WorldWideScience

Sample records for flow diodes applicable

  1. Diode laser applications in urology

    Science.gov (United States)

    Sam, Richard C.; Esch, Victor C.

    1995-05-01

    Diode lasers are air-cooled, efficient, compact devices which have the potential of very low cost when produced in quantity. The characteristics of diode lasers are discussed. Their applications in interstitial thermal treatment of the prostate, and laser ablation of prostate tissues, will be presented.

  2. Physics and Applications of Laser Diode Chaos

    CERN Document Server

    Sciamanna, Marc

    2015-01-01

    An overview of chaos in laser diodes is provided which surveys experimental achievements in the area and explains the theory behind the phenomenon. The fundamental physics underpinning this behaviour and also the opportunities for harnessing laser diode chaos for potential applications are discussed. The availability and ease of operation of laser diodes, in a wide range of configurations, make them a convenient test-bed for exploring basic aspects of nonlinear and chaotic dynamics. It also makes them attractive for practical tasks, such as chaos-based secure communications and random number generation. Avenues for future research and development of chaotic laser diodes are also identified.

  3. High Power Diode Lasers Technology and Applications

    CERN Document Server

    Bachmann, Friedrich; Poprawe, Reinhart

    2007-01-01

    In a very comprehensive way this book covers all aspects of high power diode laser technology for materials processing. Basics as well as new application oriented results obtained in a government funded national German research project are described in detail. Along the technological chain after a short introduction in the second chapter diode laser bar technology is discussed regarding structure, manufacturing technology and metrology. The third chapter illuminates all aspects of mounting and cooling, whereas chapter four gives wide spanning details on beam forming, beam guiding and beam combination, which are essential topics for incoherently coupled multi-emitter based high power diode lasers. Metrology, standards and safety aspects are the theme of chapter five. As an outcome of all the knowledge from chapter two to four various system configurations of high power diode lasers are described in chapter six; not only systems focussed on best available beam quality but especially also so called "modular" set...

  4. Flow Diode and Method for Controlling Fluid Flow Origin of the Invention

    Science.gov (United States)

    Dyson, Rodger W (Inventor)

    2015-01-01

    A flow diode configured to permit fluid flow in a first direction while preventing fluid flow in a second direction opposite the first direction is disclosed. The flow diode prevents fluid flow without use of mechanical closures or moving parts. The flow diode utilizes a bypass flowline whereby all fluid flow in the second direction moves into the bypass flowline having a plurality of tortuous portions providing high fluidic resistance. The portions decrease in diameter such that debris in the fluid is trapped. As fluid only travels in one direction through the portions, the debris remains trapped in the portions.

  5. Laser diode initiated detonators for space applications

    Science.gov (United States)

    Ewick, David W.; Graham, J. A.; Hawley, J. D.

    1993-01-01

    Ensign Bickford Aerospace Company (EBAC) has over ten years of experience in the design and development of laser ordnance systems. Recent efforts have focused on the development of laser diode ordnance systems for space applications. Because the laser initiated detonators contain only insensitive secondary explosives, a high degree of system safety is achieved. Typical performance characteristics of a laser diode initiated detonator are described in this paper, including all-fire level, function time, and output. A finite difference model used at EBAC to predict detonator performance, is described and calculated results are compared to experimental data. Finally, the use of statistically designed experiments to evaluate performance of laser initiated detonators is discussed.

  6. Investigation of MIM Diodes for RF Applications

    KAUST Repository

    Khan, Adnan

    2015-05-01

    Metal Insulator Metal (MIM) diodes that work on fast mechanism of tunneling have been used in a number of very high frequency applications such as (Infra-Red) IR detectors and optical Rectennas for energy harvesting. Their ability to operate under zero bias condition as well as the possibility of realizing them through printing makes them attractive for (Radio Frequency) RF applications. However, MIM diodes have not been explored much for RF applications. One reason preventing their widespread RF use is the requirement of a very thin oxide layer essential for the tunneling operation that requires sophisticated nano-fabrication processes. Another issue is that the reliability and stable performance of MIM diodes is highly dependent on the surface roughness of the metallic electrodes. Finally, comprehensive RF characterization has not been performed for MIM diodes reported in the literature, particularly from the perspective of their integration with antennas as well as their rectification abilities. In this thesis, various metal deposition methods such as sputtering, electron beam evaporation, and Atomic Layer Deposition (ALD) are compared in pursuit of achieving low surface roughness. It is worth mentioning here that MIM diodes realized through ALD method have been presented for the first time in this thesis. Amorphous metal alloy have also been investigated in terms of their low surface roughness. Zinc-oxide has been investigated for its suitability as a thin dielectric layer for MIM diodes. Finally, comprehensive RF characterization of MIM diodes has been performed in two ways: 1) by standard S-parameter methods, and 2) by investigating their rectification ability under zero bias operation. It is concluded from the Atomic Force Microscopy (AFM) imaging that surface roughness as low as sub 1 nm can be achieved reliably from crystalline metals such as copper and platinum. This value is comparable to surface roughness achieved from amorphous alloys, which are non

  7. High-power green diode laser systems for biomedical applications

    DEFF Research Database (Denmark)

    Müller, André

    Due to their unique characteristics, diode lasers are increasingly attractive for numerous applications. For example, in the biomedical field the provided output power, spatial quality, and wavelength coverage of diode lasers has enabled their applications in, e.g., dermatology, diffuse spectrosc......Due to their unique characteristics, diode lasers are increasingly attractive for numerous applications. For example, in the biomedical field the provided output power, spatial quality, and wavelength coverage of diode lasers has enabled their applications in, e.g., dermatology, diffuse......, the obtained results clearly strengthen the application potential of diode lasers, including the biomedical field....

  8. Diode laser based light sources for biomedical applications

    DEFF Research Database (Denmark)

    Müller, André; Marschall, Sebastian; Jensen, Ole Bjarlin;

    2013-01-01

    Diode lasers are by far the most efficient lasers currently available. With the ever-continuing improvement in diode laser technology, this type of laser has become increasingly attractive for a wide range of biomedical applications. Compared to the characteristics of competing laser systems, diode...... imaging. This review provides an overview of the latest development of diode laser technology and systems and their use within selected biomedical applications....

  9. Cascading Tesla Oscillating Flow Diode for Stirling Engine Gas Bearings

    Science.gov (United States)

    Dyson, Rodger

    2012-01-01

    Replacing the mechanical check-valve in a Stirling engine with a micromachined, non-moving-part flow diode eliminates moving parts and reduces the risk of microparticle clogging. At very small scales, helium gas has sufficient mass momentum that it can act as a flow controller in a similar way as a transistor can redirect electrical signals with a smaller bias signal. The innovation here forces helium gas to flow in predominantly one direction by offering a clear, straight-path microchannel in one direction of flow, but then through a sophisticated geometry, the reversed flow is forced through a tortuous path. This redirection is achieved by using microfluid channel flow to force the much larger main flow into this tortuous path. While microdiodes have been developed in the past, this innovation cascades Tesla diodes to create a much higher pressure in the gas bearing supply plenum. In addition, the special shape of the leaves captures loose particles that would otherwise clog the microchannel of the gas bearing pads.

  10. Planar GaAs diodes for THz frequency mixing applications

    Science.gov (United States)

    Bishop, William L.; Crowe, Thomas W.; Mattauch, Robert J.; Dossal, Hasan

    1992-01-01

    Schottky barrier diodes for terahertz applications are typically fabricated as a micron to sub-micron circular anode metallization on GaAs which is contacted with a sharp wire (whisker). This structure has the benefits of the simplicity of the fabrication of the diode chip, the minimal shunt capacitance of the whisker contact and the ability of the whisker wire to couple energy to the diode. However, whisker-contacted diodes are costly to assembly and difficult to qualify for space applications. Also, complex receiver systems which require many diodes are difficult to assemble. The objective of this paper is to discuss the advantages of planar Schottky diodes for high frequency receiver applications and to summarize the problems of advancing the planar technology to the terahertz frequency range. Section 2 will discuss the structure, fabrication and performance of state-of-the-art planar Schottky diodes. In Section 3 the problems of designing and fabricating planar diodes for terahertz frequency operation are discussed along with a number of viable solutions. Section 4 summarizes the need for further research and cooperation between diode designers and RF engineers.

  11. Application of spherical micro diodes for brachytherapy dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Broisman, Andrey, E-mail: andreybr@ariel.ac.i [Medical Physics, Ariel University Center, Ariel 40700 (Israel); Shani, Gad [Biomedical Engineering, Ben Gurion University, P.O. Box 653, Beer Sheva 84105 (Israel)

    2011-03-15

    The research presented in this paper demonstrates the feasibility and the advantages of using spherical micro diodes for radiation dosimetry. The spherical symmetry of the diode response is demonstrated, compared to that of planar diodes. The application of the spherical diode described here is for radiotherapy dosimetry, particularly brachytherapy. Measurements were done in PMMA phantoms. The advantage of the spherical diode is that it can be used for radiation measurement in a 4{pi} geometry, it was demonstrated by measurements in both axial and azimuthal planes. The diodes were found to respond equally to radiation coming from all directions, directly from the source or due to scattered radiation within the medium. In the present work 1.8 mm diameter silicone diodes were used. The small size of these spherical diodes provides local dose measurement and can be used for in situ dosimetry while treatment takes place. Treatment planning correction can be made accordingly. Commercially available seeds of the isotopes I{sup 125} and Pd{sup 103} were used as radiation sources. The spherical diodes response was compared with that of planar diodes XRB generally used for UV and X-ray dosimetry, and with TLD measurements. We have also compared the measured results with Monte Carlo simulation, applying the MCNP code and with calculations shown in the TG-43 report.

  12. Advanced laser diodes for sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    VAWTER,GREGORY A.; MAR,ALAN; CHOW,WENG W.; ALLERMAN,ANDREW A.

    2000-01-01

    The authors have developed diode lasers for short pulse duration and high peak pulse power in the 0.01--100.0 m pulsewidth regime. A primary goal of the program was producing up to 10 W while maintaining good far-field beam quality and ease of manufacturability for low cost. High peak power, 17 W, picosecond pulses have been achieved by gain switching of flared geometry waveguide lasers and amplifiers. Such high powers area world record for this type of diode laser. The light emission pattern from diode lasers is of critical importance for sensing systems such as range finding and chemical detection. They have developed a new integrated optical beam transformer producing rib-waveguide diode lasers with a symmetric, low divergence, output beam and increased upper power limits for irreversible facet damage.

  13. Diode pumped solid-state laser oscillators for spectroscopic applications

    Science.gov (United States)

    Byer, R. L.; Basu, S.; Fan, T. Y.; Kozlovsky, W. J.; Nabors, C. D.; Nilsson, A.; Huber, G.

    1987-01-01

    The rapid improvement in diode laser pump sources has led to the recent progress in diode laser pumped solid state lasers. To date, electrical efficiencies of greater than 10 percent were demonstrated. As diode laser costs decrease with increased production volume, diode laser and diode laser array pumped solid state lasers will replace the traditional flashlamp pumped Nd:YAG laser sources. The use of laser diode array pumping of slab geometry lasers will allow efficient, high peak and average power solid state laser sources to be developed. Perhaps the greatest impact of diode laser pumped solid state lasers will be in spectroscopic applications of miniature, monolithic devices. Single-stripe diode-pumped operation of a continuous-wave 946 nm Nd:YAG laser with less than 10 m/w threshold was demonstrated. A slope efficiency of 16 percent near threshold was shown with a projected slope efficiency well above a threshold of 34 percent based on results under Rhodamine 6G dye-laser pumping. Nonlinear crystals for second-harmonic generation of this source were evaluated. The KNbO3 and periodically poled LiNbO3 appear to be the most promising.

  14. Blue laser diode (LD) and light emitting diode (LED) applications

    Science.gov (United States)

    Bergh, Arpad A.

    2004-09-01

    The family of blue LEDs, edge emitting and surface emitting lasers, enable a number of applications. Blue lasers are used in digital applications such as optical storage in high density DVDs. The resolution of the spot size and hence the storage density is diffraction limited and is inversely proportional to the square of the wavelength of the laser. Other applications include printing, optical scanners, and high-resolution photo-lithography.As light emitters, blue LEDs are used for signaling and in direct view large area emissive displays. They are also making inroads into signage and LCD back-lighting, mobile platforms, and decorative accent lighting in curtains, furniture, etc.Blue LEDs produce white light either with phosphor wavelength converters or in combination with red and green LEDs. The full potential of LED light sources will require three devices to enable complete control over color and intensity.Sensing and medical/bio applications have a major impact on home security, on monitoring the environment, and on health care. New emerging diagnostic and therapeutic applications will improve the quality and reduce the cost of health care.

  15. Applications of microlens-conditioned laser diode arrays

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R.J.; Emanuel, M.A.; Freitas, B.L. [and others

    1995-01-01

    The ability to condition the radiance of laser diodes using shaped-fiber cylindrical-microlens technology has dramatically increased the number of applications that can be practically engaged by diode laser arrays. Lawrence Livermore National Laboratory (LLNL) has actively pursued optical efficiency and engineering improvements in this technology in an effort to supply large radiance-conditioned laser diode array sources for its own internal programs. This effort has centered on the development of a modular integrated laser diode packaging technology with the goal of enabling the simple and flexible construction of high average power, high density, two-dimensional arrays with integrated cylindrical microlenses. Within LLNL, the principal applications of microlens-conditioned laser diode arrays are as high intensity pump sources for diode pumped solid state lasers (DPSSLs). A simple end-pumping architecture has been developed and demonstrated that allows the radiation from microlens-conditioned, two-dimensional diode array apertures to be efficiently delivered to the end of rod lasers. To date, pump powers as high as 2.5 kW have been delivered to 3 mm diameter laser rods. Such high power levels are critical for pumping solid state lasers in which the terminal laser level is a Stark level lying in the ground state manifold. Previously, such systems have often required operation of the solid state gain medium at low temperature to freeze out the terminal laser Stark level population. The authors recently developed high intensity pump sources overcome this difficulty by effectively pumping to much higher inversion levels, allowing efficient operation at or near room temperature. Because the end-pumping technology is scalable in absolute power, the number of rare-earth ions and transitions that can be effectively accessed for use in practical DPSSL systems has grown tremendously.

  16. GaAs IMPATT diodes for microstrip circuit applications.

    Science.gov (United States)

    Wisseman, W. R.; Tserng, H. Q.; Shaw, D. W.; Mcquiddy, D. N.

    1972-01-01

    GaAs IMPATT diodes with plated heat sinks are shown to be particularly well suited for microstrip circuit applications. Details of materials growth and device fabrication procedures are given, and experimental results are presented for a GaAs IMPATT microstrip oscillator operating at X band.

  17. Component validation of direct diode 488nm lasers in BD Accuri C6 flow cytometers

    Science.gov (United States)

    Chen, Wei P.; Luo, Ningyi D.

    2016-03-01

    The 488nm laser is the most important excitation light source of flow cytometry. The indirect diode (frequency-doubled diode) 488nm lasers are used in the excitation of Becton Dickinson (BD) AccuriTM C6. For using cost effective lasers, we have validated direct diode 488nm lasers as the replacement component of frequency-doubled diode laser. BD Bioscience issued the protocols to cover wavelength, power, noise, and polarization at the operation temperature range of cytometer. Pavilion Integration Corporation (PIC) tested 6 samples as the component validation of direct diode 488nm lasers based on the protocols from BD Biosciences. BD Bioscience also tested one of laser samples to further validate the test results of power, noise, and polarization from PIC.

  18. High-power diode lasers and their direct industrial applications

    Science.gov (United States)

    Loosen, Peter; Treusch, Hans-Georg; Haas, C. R.; Gardenier, U.; Weck, Manfred; Sinnhoff, V.; Kasperowski, S.; vor dem Esche, R.

    1995-04-01

    The paper summarizes activities of the two Fraunhofer-Institutes ILT and IPT concerning the development of high-power laser-diode stacks and their direct industrial applications. With microchannel coolers in copper technology and ultra-precision machined micro-optics a stack of 330 - 400 W total power with a maximum intensity of the focused beam of 2 104 W/cm2 has been built and tested in first applications. By further improvements of the lens-fabrication and -alignment technology as well as increase of the number of stacked diodes an output power in the kW-range and intensities up to about 105 W/cm2 shall be achieved in the near future. Applications of such laser sources in surface technology, in the processing of plastics, in laser-assisted machining and in brazing are discussed.

  19. Power blue and green laser diodes and their applications

    Science.gov (United States)

    Hager, Thomas; Strauß, Uwe; Eichler, Christoph; Vierheilig, Clemens; Tautz, Sönke; Brüderl, Georg; Stojetz, Bernhard; Wurm, Teresa; Avramescu, Adrian; Somers, André; Ristic, Jelena; Gerhard, Sven; Lell, Alfred; Morgott, Stefan; Mehl, Oliver

    2013-03-01

    InGaN based green laser diodes with output powers up to 50mW are now well established for variety of applications ranging from leveling to special lighting effects and mobile projection of 12lm brightness. In future the highest market potential for visible single mode profile lasers might be laser projection of 20lm. Therefore direct green single-mode laser diodes with higher power are required. We found that self heating was the limiting factor for higher current operation. We present power-current characteristics of improved R and D samples with up to 200mW in cw-operation. An optical output power of 100mW is reached at 215mA, a current level which is suitable for long term operation. Blue InGaN laser diodes are also the ideal source for phosphor based generation of green light sources of high luminance. We present a light engine based on LARP (Laser Activated Remote Phosphor) which can be used in business projectors of several thousand lumens on screen. We discuss the advantages of a laser based systems in comparison with LED light engines. LARP requires highly efficient blue power laser diodes with output power above 1W. Future market penetration of LARP will require lower costs. Therefore we studied new designs for higher powers levels. R and D chips with power-current characteristics up to 4W in continuous wave operation on C-mount at 25°C are presented.

  20. Simultaneous measurements of multiple flow parameters for scramjet characterization using tunable diode-laser sensors.

    Science.gov (United States)

    Li, Fei; Yu, Xilong; Gu, Hongbin; Li, Zhi; Zhao, Yan; Ma, Lin; Chen, Lihong; Chang, Xinyu

    2011-12-20

    This paper reports the simultaneous measurements of multiple flow parameters in a scramjet facility operating at a nominal Mach number of 2.5 using a sensing system based on tunable diode-laser absorption spectroscopy (TDLAS). The TDLAS system measures velocity, temperature, and water vapor partial pressure at three different locations of the scramjet: the inlet, the combustion region near the flame stabilization cavity, and the exit of the combustor. These measurements enable the determination of the variation of the Mach number and the combustion mode in the scramjet engine, which are critical for evaluating the combustion efficiency and optimizing engine performance. The results obtained in this work clearly demonstrated the applicability of TDLAS sensors in harsh and high-speed environments. The TDLAS system, due to its unique virtues, is expected to play an important role in the development of scramjet engines.

  1. Planar Schottky barrier mixer diodes for space applications at submillimeter wavelengths

    Science.gov (United States)

    Bishop, W. L.; Crowe, T. W.; Mattauch, R. J.; Ostdiek, P. H.

    1991-01-01

    Available planar diodes for space-based applications at submillimeter wavelengths have not achieved either the required low junction capacitance or the low series resistance-junction capacitance product. Here, the development of a novel planar diode structure that overcomes both of these difficulties is outlined. The characteristics of these Schottky barrier mixer diodes are presented and electron micrographs are shown. The diode structure will allow planar technology to be extended throughout the submillimeter wavelength range.

  2. Moderately converging ion and electron flows in two-dimensional diodes

    Science.gov (United States)

    Cavenago, M.

    2012-11-01

    Flow of particles in diodes is solved selfconsistently assuming an approximated system of flow lines, that can be easily represented by an analytic transformation in a complex plane, with assumed uniformity in the third spatial direction. Beam current compression is tunable by an angle parameter α0; transformed coordinate lines are circular arcs, exactly matching to the curved cathode usually considered by rectilinear converging flows. The curvature of flow lines allows to partly balance the transverse effect of space charge. A self-contained discussion of the whole theory is reported, ranging from analytical solution for selfconsistent potential to electrode drawing to precise numerical simulation, which serves as a verification and as an illustration of typical electrode shapes. Motion and Poisson equation are written in a curved flow line system and their approximate consistency is shown to imply an ordinary differential equation for the beam edge potential. Transformations of this equation and their series solutions are given and discussed, showing that beam edge potential has a maximum, so supporting both diode (with α0 ≅ π/3) and triode design. Numerical simulations confirm the consistency of these solution. Geometrical details of diode design are discussed: the condition of a zero divergence beam, with the necessary anode lens effect included, is written and solved, as a function of beam compression; accurate relations for diode parameters and perveance are given. Weakly relativistic effects including self-magnetic field are finally discussed as a refinement.

  3. Light-emitting diodes - Their potential in biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Naichia Gary; Wu, Chia-Hao [College of Applied Sciences, MingDao University, 369 Wen-Hua Road, Peetou, Changhua 52345 (China); Cheng, Ta Chih [Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, 1 Hseuh-Fu Rd., Nei-Pu Hsiang, Pingtung 91201 (China)

    2010-10-15

    The rapid development of high brightness light-emitting diodes (LEDs) makes feasible the use of LEDs, among other light sources (such as laser, intense pulse light and other incoherent light systems), for medical treatment and light therapy. This paper provides a general review on red, green, blue, ultraviolet LED applications in photo rejuvenation and medical treatments of a variety of physical abnormalities, as well as the relief of stress, circadian rhythm disorders, and seasonal affective disorder. The review, concentrated in the papers published after 1990, intends to show that LEDs are well qualified to succeed its more energy demanding counterparts in the named areas and beyond. (author)

  4. Pulsed operation of high power light emitting diodes for flow velocimetry

    OpenAIRE

    Willert, Christian; Mößner, Steffen; Klinner, Joachim

    2009-01-01

    High powered light emitting diodes (LED) are investigated for possible uses as light sources in flow diagnostics, in particular, as an alternative to laser-based illumination in particle imaging flow velocimetry. Recent developments in solid state illumination resulted in mass-produced LEDs that provide average radiant power in excess of 10 Watt. By operating these LEDs with short duration, pulsed currents that are considerably beyond their continuous current damage th...

  5. Pulsed operation of high-power light emitting diodes for imaging flow velocimetry

    OpenAIRE

    Willert, Christian; Stasicki, Boleslaw; Klinner, Joachim; Moessner, S.

    2010-01-01

    High-powered light emitting diodes (LED) are investigated for possible uses as light sources in flow diagnostics, in particular, as an alternative to laser-based illumination in particle imaging flow velocimetry in side-scatter imaging arrangements. Recent developments in solid state illumination resulted in mass-produced LEDs that provide average radiant power in excess of 10 W. By operating these LEDs with short duration, pulsed currents that are considerably beyond their continuous c...

  6. Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

    Science.gov (United States)

    Martin, Marcel Nations; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George

    2013-01-01

    A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions.

  7. Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

    Science.gov (United States)

    Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

    2011-01-01

    Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

  8. Diode-pumped all-solid-state lasers and applications

    CERN Document Server

    Parsons-Karavassilis, D

    2002-01-01

    This thesis describes research carried out by the within the Physics Department at Imperial College that was aimed at developing novel all-solid-state laser sources and investigating potential applications of this technology. A description of the development, characterisation and application of a microjoule energy level, diode-pumped all-solid-state Cr:LiSGAF femtosecond oscillator and regenerative amplifier system is presented. The femtosecond oscillator was pumped by two commercially available laser diodes and produced an approx 80 MHz pulse train of variable pulse duration with approx 30 mW average output power and a tuning range of over approx 60 nm. This laser oscillator was used to seed a regenerative amplifier, resulting in adjustable repetition rate (single pulse to 20 kHz) approx 1 mu J picosecond pulses. These pulses were compressed to approx 150 fs using a double-pass twin-grating compressor. The amplifier's performance was investigated with respect to two different laser crystals and different pul...

  9. III-nitride based light emitting diodes and applications

    CERN Document Server

    Han, Jung; Amano, Hiroshi; Morkoç, Hadis

    2017-01-01

    The revised edition of this important book presents updated and expanded coverage of light emitting diodes (LEDs) based on heteroepitaxial GaN on Si substrates, and includes new chapters on tunnel junction LEDs, green/yellow LEDs, and ultraviolet LEDs. Over the last two decades, significant progress has been made in the growth, doping and processing technologies of III-nitride based semiconductors, leading to considerable expectations for nitride semiconductors across a wide range of applications. LEDs are already used in traffic signals, signage lighting, and automotive applications, with the ultimate goal of the global replacement of traditional incandescent and fluorescent lamps, thus reducing energy consumption and cutting down on carbon-dioxide emission. However, some critical issues must be addressed to allow the further improvements required for the large-scale realization of solid-state lighting, and this book aims to provide the readers with details of some contemporary issues on which the performanc...

  10. Study of pseudo noise CW diode laser for ranging applications

    Science.gov (United States)

    Lee, Hyo S.; Ramaswami, Ravi

    1992-11-01

    A new Pseudo Random Noise (PN) modulated CW diode laser radar system is being developed for real time ranging of targets at both close and large distances (greater than 10 KM) to satisy a wide range of applications: from robotics to future space applications. Results from computer modeling and statistical analysis, along with some preliminary data obtained from a prototype system, are presented. The received signal is averaged for a short time to recover the target response function. It is found that even with uncooperative targets, based on the design parameters used (200-mW laser and 20-cm receiver), accurate ranging is possible up to about 15 KM, beyond which signal to noise ratio (SNR) becomes too small for real time analog detection.

  11. Qualification and Selection of Flight Diode Lasers for Space Applications

    Science.gov (United States)

    Liebe, Carl C.; Dillon, Robert P.; Gontijo, Ivair; Forouhar, Siamak; Shapiro, Andrew A.; Cooper, Mark S.; Meras, Patrick L.

    2010-01-01

    The reliability and lifetime of laser diodes is critical to space missions. The Nuclear Spectroscopic Telescope Array (NuSTAR) mission includes a metrology system that is based upon laser diodes. An operational test facility has been developed to qualify and select, by mission standards, laser diodes that will survive the intended space environment and mission lifetime. The facility is situated in an electrostatic discharge (ESD) certified clean-room and consist of an enclosed temperature-controlled stage that can accommodate up to 20 laser diodes. The facility is designed to characterize a single laser diode, in addition to conducting laser lifetime testing on up to 20 laser diodes simultaneously. A standard laser current driver is used to drive a single laser diode. Laser diode current, voltage, power, and wavelength are measured for each laser diode, and a method of selecting the most adequate laser diodes for space deployment is implemented. The method consists of creating histograms of laser threshold currents, powers at a designated current, and wavelengths at designated power. From these histograms, the laser diodes that illustrate a performance that is outside the normal are rejected and the remaining lasers are considered spaceborne candidates. To perform laser lifetime testing, the facility is equipped with 20 custom laser drivers that were designed and built by California Institute of Technology specifically to drive NuSTAR metrology lasers. The laser drivers can be operated in constant-current mode or alternating-current mode. Situated inside the enclosure, in front of the laser diodes, are 20 power-meter heads to record laser power throughout the duration of lifetime testing. Prior to connecting a laser diode to the current source for characterization and lifetime testing, a background program is initiated to collect current, voltage, and resistance. This backstage data collection enables the operational test facility to have full laser diode

  12. III-nitride based light emitting diodes and applications

    CERN Document Server

    Han, Jung; Amano, Hiroshi; Morkoç, Hadis

    2013-01-01

    Light emitting diodes (LEDs) are already used in traffic signals, signage lighting, and automotive applications. However, its ultimate goal is to replace traditional illumination through LED lamps since LED lighting significantly reduces energy consumption and cuts down on carbon-dioxide emission. Despite dramatic advances in LED technologies (e.g., growth, doping and processing technologies), however, there remain critical issues for further improvements yet to be achieved for the realization of solid-state lighting. This book aims to provide the readers with some contemporary LED issues, which have not been comprehensively discussed in the published books and, on which the performance of LEDs is seriously dependent. For example, most importantly, there must be a breakthrough in the growth of high-quality nitride semiconductor epitaxial layers with a low density of dislocations, in particular, in the growth of Al-rich and and In-rich GaN-based semiconductors. The materials quality is directly dependent on th...

  13. Measurement of transient gas flow parameters by diode laser absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bolshov, M A; Kuritsyn, Yu A; Liger, V V; Mironenko, V R [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow (Russian Federation); Nadezhdinskii, A I; Ponurovskii, Ya Ya [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Leonov, S B; Yarantsev, D A [Reserch Center of High Energy Densities Physics, Joint Institute for High Temperatures, Russian Academy of Sciences (Russian Federation)

    2015-04-30

    An absorption spectrometer based on diode lasers is developed for measuring two-dimension maps of temperature and water vapour concentration distributions in the combustion zones of two mixing supersonic flows of fuel and oxidiser in the single run regime. The method of measuring parameters of hot combustion zones is based on detection of transient spectra of water vapour absorption. The design of the spectrometer considerably reduces the influence of water vapour absorption along the path of a sensing laser beam outside the burning chamber. The optical scheme is developed, capable of matching measurement results in different runs of mixture burning. A new algorithm is suggested for obtaining information about the mixture temperature by constructing the correlation functions of the experimental spectrum with those simulated from databases. A two-dimensional map of temperature distribution in a test chamber is obtained for the first time under the conditions of plasma-induced combusion of the ethylene – air mixture. (laser applications and other topics in quantum electronics)

  14. Simultaneous measurements of multiple flow parameters for scramjet characterization using tunable diode-laser sensors

    OpenAIRE

    Li, Fei; Yu, XiLong; Gu, Hongbin; Li, Zhi; Zhao, Yan; Ma, Lin; Chen, Lihong; Chang, Xinyu

    2011-01-01

    This paper reports the simultaneous measurements of multiple flow parameters in a scramjet facility operating at a nominal Mach number of 2.5 using a sensing system based on tunable diode-laser absorption spectroscopy (TDLAS). The TDLAS system measures velocity, temperature, and water vapor partial pressure at three different locations of the scramjet: the inlet, the combustion region near the flame stabilization cavity, and the exit of the combustor. These measurements enable the determinati...

  15. Application of Diode Laser in the Treatment of Dentine Hypersensitivity

    Science.gov (United States)

    Gojkov-Vukelic, Mirjana; Hadzic, Sanja; Zukanovic, Amila; Pasic, Enes; Pavlic, Veriva

    2016-01-01

    Introduction: Dentine hypersensitivity is characterized by acute, sharp pain arising from the exposed dentine, most commonly in response to thermal, tactile, or chemical stimuli, and which cannot be linked to any other pathological changes in the tooth or the environment. Therapy uses various impregnating agents in the form of solutions or gels and, in more recent times, laser. Aim: The aim of this research was to examine the effects of treatment of hypersensitive dental cervix with diode laser. Materials and Methods: The study included 18 patients with 82 sensitive teeth. The degree of dentine hypersensitivity was evaluated by visual analogue scale (VAS), and the treatment was carried out by application of low-power diode laser over the span of three visits, which depended on the initial sensitivity. Results: There is a significant difference in VAS values measured at the onset of treatment (baseline) and immediately after the first laser treatment (t=9.275; p=0.000), after 7 days, after the second laser treatment (14 days) (t=7.085, p=0.000), as well as after 14 days and the third laser treatment (t=5.517, p=0.000), which confirms the effectiveness of this therapeutic procedure. The results showed a reduction of hypersensitivity in response to tactile stimulus with a probe after the third treatment, even with teeth whose value on the VAS was very high at the beginning of treatment (baseline). Conclusion: Within the scope of the conducted study, laser therapy has provided extremely safe and effective results in the treatment of cervical dentine hypersensitivity.

  16. Diode-pumped Alexandrite ring laser for lidar applications

    Science.gov (United States)

    Munk, A.; Jungbluth, B.; Strotkamp, M.; Hoffmann, H.-D.; Poprawe, R.; Höffner, J.

    2016-03-01

    We present design and performance data of a diode-pumped Q-switched Alexandrite ring laser in the millijoule regime, which is longitudinally pumped by laser diode bar modules in the red spectral range. As a first step, a linear resonator was designed and characterized in qcw operation as well as in Q-switched operation. Based on these investigations, two separate linear cavities were set up, each with one Alexandrite crystal longitudinally pumped by one diode module. The two cavities are fused together and form a ring cavity which yields up to 6 mJ pulse burst energy in the qcw regime at 770 nm.

  17. Physical based Schottky barrier diode modeling for THz applications

    DEFF Research Database (Denmark)

    Yan, Lei; Krozer, Viktor; Michaelsen, Rasmus Schandorph;

    2013-01-01

    In this work, a physical Schottky barrier diode model is presented. The model is based on physical parameters such as anode area, Ohmic contact area, doping profile from epitaxial (EPI) and substrate (SUB) layers, layer thicknesses, barrier height, specific contact resistance, and device...... temperature. The effects of barrier height lowering, nonlinear resistance from the EPI layer, and hot electron noise are all included for accurate characterization of the Schottky diode. To verify the diode model, measured I-V and C-V characteristics are compared with the simulation results. Due to the lack...

  18. Direct diode lasers and their advantages for materials processing and other applications

    Science.gov (United States)

    Fritsche, Haro; Ferrario, Fabio; Koch, Ralf; Kruschke, Bastian; Pahl, Ulrich; Pflueger, Silke; Grohe, Andreas; Gries, Wolfgang; Eibl, Florian; Kohl, Stefanie; Dobler, Michael

    2015-03-01

    The brightness of diode lasers is improving continuously and has recently started to approach the level of some solid state lasers. The main technology drivers over the last decade were improvements of the diode laser output power and divergence, enhanced optical stacking techniques and system design, and most recently dense spectral combining. Power densities at the work piece exceed 1 MW/cm2 with commercially available industrial focus optics. These power densities are sufficient for cutting and welding as well as ablation. Single emitter based diode laser systems further offer the advantage of fast current modulation due their lower drive current compared to diode bars. Direct diode lasers may not be able to compete with other technologies as fiber or CO2-lasers in terms of maximum power or beam quality. But diode lasers offer a range of features that are not possible to implement in a classical laser. We present an overview of those features that will make the direct diode laser a very valuable addition in the near future, especially for the materials processing market. As the brightness of diode lasers is constantly improving, BPP of less than 5mm*mrad have been reported with multikW output power. Especially single emitter-based diode lasers further offer the advantage of very fast current modulation due to their low drive current and therefore low drive voltage. State of the art diode drivers are already demonstrated with pulse durations of cost effective lasers is enabled. The wide variety of wavelengths, high brightness, fast power modulation and high efficiency of diode lasers results in a strong pull of existing markets, but also spurs the development of a wide variety of new applications.

  19. Manufacturing Practices for Silicon-Based Power Diode in Fast Recovery Applications

    Directory of Open Access Journals (Sweden)

    N. Harihara Krishnan

    2011-01-01

    Full Text Available This paper reports a fast recovery semiconductor diode that was developed for use in high power applications. The diode constructed in disc-type ceramic package with a peak-inverse voltage rating of 2800 V and current rating of 710 A was fabricated using float-zone (FZ silicon wafer as the starting raw material. Alternate processes viz. gold diffusion, gamma irradiation and electron irradiation were explored for control of carrier lifetime required to tune the switching response of the diode to the desired value of 8 μs. The paper compares the results of these alternate processes. The diodes were fabricated and tested for forward conduction, reverse blocking and switching characteristics. The measured values were observed to be comparable with the design requirements. The paper presents an overview of the design, manufacturing and testing practices adopted to meet the desired diode characteristics and ratings.

  20. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.

    1994-01-01

    The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL`s). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL`s which are appropriate for material processing applications, low and intermediate average power DPSSL`s are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications.

  1. Pulsed operation of high-power light emitting diodes for imaging flow velocimetry

    Science.gov (United States)

    Willert, C.; Stasicki, B.; Klinner, J.; Moessner, S.

    2010-07-01

    High-powered light emitting diodes (LED) are investigated for possible uses as light sources in flow diagnostics, in particular, as an alternative to laser-based illumination in particle imaging flow velocimetry in side-scatter imaging arrangements. Recent developments in solid state illumination resulted in mass-produced LEDs that provide average radiant power in excess of 10 W. By operating these LEDs with short duration, pulsed currents that are considerably beyond their continuous current damage threshold, light pulses can be generated that are sufficient to illuminate and image micron-sized particles in flow velocimetry. Time-resolved PIV measurements in water at a framing rate of 2kHz are presented. The feasibility of LED-based PIV measurements in air is also demonstrated.

  2. Selective-area nanoheteroepitaxy for light emitting diode (LED) applications

    Science.gov (United States)

    Wildeson, Isaac H.

    generate built-in electric fields with magnitudes that are one-tenth those on the polar c-plane with the same (In,Ga)N composition. The lateral strain relaxation innate in the nanoheterostructures allows greater coherent InN incorporation in the nanopyramids as compared to thin-film heterostructures, as confirmed by electroluminescence and transmission electron microscopy. In addition to applications for light emitting diodes, selective area growth of GaN nanostructures is also important for biological and sensing applications. A process for fabricating porous GaN nanorods is presented that also relies on selective-area organometallic vapor phase epitaxy. The nanopore walls are primarily outlined by nonpolar planes, and the diameter of the nanopore can be controlled by the diameter of the opening in the dielectric template and the growth time. The lining of the nanopore walls is comprised of crystalline GaN, which makes these structures interesting for sensing, electrical and optical applications.

  3. Metal-insulator-metal diodes with sub-nanometre surface roughness for energy-harvesting applications

    KAUST Repository

    Khan, A.A.

    2017-07-27

    For ambient radio-frequency (RF) energy harvesting, the available power levels are quite low, and it is highly desirable that the rectifying diodes do not consume any power at all. Contrary to semiconducting diodes, a tunnelling diode – also known as a metal-insulator-metal (MIM) diode – can provide zero-bias rectification, provided the two metals have different work functions. This could result in a complete passive rectenna system. Despite great potential, MIM diodes have not been investigated much in the GHz-frequency regime due to challenging nano-fabrication requirements. In this work, we investigate zero-bias MIM diodes for RF energy-harvesting applications. We studied the surface roughness issue for the bottom metal of the MIM diode for various deposition techniques such as sputtering, atomic layer deposition (ALD) and electron-beam (e-beam) evaporation for crystalline metals as well as for an amorphous alloy, namely ZrCuAlNi. A surface roughness of sub-1nm has been achieved for both the crystalline metals as well as the amorphous alloy, which is vital for the reliable operation of the MIM diode. An MIM diode comprising of a Ti-ZnO-Pt combination yields a zero-bias responsivity of 0.25V−1 and a dynamic resistance of 1200Ω. Complete RF characterisation has been performed by integrating the MIM diode with a coplanar waveguide transmission line. The input impedance varies from 100Ω to 50Ω in the frequency range of between 2GHz and 10GHz, which can be easily matched to typical antenna impedances in this frequency range. Finally, a rectified DC voltage of 4.7mV is obtained for an incoming RF power of 0.4W at zero bias. These preliminary results of zero-bias rectification indicate that complete, passive rectennas (a rectifier and antenna combination) are feasible with further optimisation of MIM devices.

  4. 2 transistors + 2 diodes-based PEBB designed for general applications in power electronics

    OpenAIRE

    Nicolás Apruzzese, Joan; Rocabert Delgado, Joan; Bordonau Farrerons, José; Busquets Monge, Sergio; Alepuz Menéndez, Salvador; Martínez Velasco, Juan Antonio; Peracaula Roura, Joan

    2009-01-01

    This paper presents a new Power Electronic Building Block (PEBB) designed to facilitate the implementation of different power converter topologies. The proposed PEBB consists of two diodes and two transistors and it can be used to implement the most relevant power converter topologies, due to its modularity. The addition of the two diodes is an exclusive feature of the new PEBB, which permits to implement neutral point clamped (NPC) multilevel converters. The application of the PE...

  5. Practical applications of the diode in dental practice

    Science.gov (United States)

    Moldoveanu, Lucia E.; Odor, Alin A.

    2016-03-01

    Introduction: The use of lasers has become a practice in modern periodontology and it is a fact that the use of diodes in the dental office can bring a real benefit in periodontal surgery. Material and method: These case reports describe few of various soft tissue procedures that were performed with diode laser 940 nm (Epic 10, Biolase Inc., USA). Discussions: There are a few immediate benefits of the intervention: the "periodontal bandage" belongs to the patient, the procedure is painless, performed under a superficial anesthesia and the psychological impact on the patient, as well as the acceptance, are superior to conventional methods of dentistry. Conclusions: Diode lasers at the level of periodontium have become a significant part of the dentistry, reducing the patient's stress and giving satisfaction to practitioners as well.

  6. Evaluation of light-emitting diodes for signage applications

    Science.gov (United States)

    Freyssinier, Jean Paul; Zhou, Yutao; Ramamurthy, Vasudha; Bierman, Andrew; Bullough, John D.; Narendran, Nadarajah

    2004-01-01

    This paper outlines two parts of a study designed to evaluate the use of light-emitting diodes (LEDs) in channel-letter signs. The first part of the study evaluated the system performance of red LED signs and white LED signs against reference neon and cold-cathode signs. The results show a large difference between the actual performance and potential savings from red and white LEDs. Depending on the configuration, a red LED sign could use 20% to 60% less power than a neon sign at the same light output. The light output of the brightest white LED sign tested was 15% lower than the cold-cathode reference, but its power was 53% higher. It appears from this study that the most efficient white LED system is still 40% less efficient than the cold-cathode system tested. One area that offers a great potential for further energy savings is the acrylic diffuser of the signs. The acrylic diffusers measured absorb between 60% and 66% of the light output produced by the sign. Qualitative factors are also known to play an important role in signage systems. One of the largest issues with any new lighting technology is its acceptance by the end user. Consistency of light output and color among LEDs, even from the same manufacturing batch, and over time, are two of the major issues that also could affect the advantages of LEDs for signage applications. To evaluate different signage products and to identify the suitability of LEDs for this application, it is important to establish a criterion for brightness uniformity. Building upon this information, the second part of the study used human factors evaluations to determine a brightness-uniformity criterion for channel-letter signs. The results show that the contrast modulation between bright and dark areas within a sign seems to elicit the strongest effect on how people perceive uniformity. A strong monotonic relationship between modulation and acceptability was found in this evaluation. The effect of contrast seems to be stronger

  7. New class of compact diode pumped sub 10 fs lasers for biomedical applications

    DEFF Research Database (Denmark)

    Le, T.; Mueller, A.; Sumpf, B.;

    2016-01-01

    -laser. In this work we present an alternative method by deploying frequency-doubled IR diodes with good beam qualities to pump fs-lasers. The revolutionary approach allows choosing any pump wavelengths in the green region and avoids complicated relay optics for the diodes. For the first time we show results...... of a diode-pumped 10 fs-laser and how a single diode setup can be integrated into a 30 x 30 cm(2) fs-laser system generating sub 20 fs laser pulses with output power towards half a Watt. This technology paves the way for a new class of very compact and cost-efficient fs-lasers for life science and industrial...... applications....

  8. Development of GaAs Gunn Diodes and Their Applications to Frequency Modulated Continuous Wave Radar

    Science.gov (United States)

    Choi, Seok-Gyu; Han, Min; Baek, Yong-Hyun; Ko, Dong-Sik; Baek, Tae-Jong; Lee, Sang-Jin; Kim, Jin-Ho; Lee, Seong-Dae; Kim, Mi-Ra; Chae, Yeon-Sik; Kathalingam, Adaikalam; Rhee, Jin-Koo

    2010-11-01

    In this work, we have designed and fabricated the GaAs Gunn diodes for a 94 GHz waveguide voltage controlled oscillator (VCO) which is one of the important parts in a frequency modulated continuous wave (FMCW) radar application. For fabrication of the high power GaAs Gunn diodes, we adopted a graded gap injector which enhances the output power and conversion efficiency by effectively removing the dead-zone. We have measured RF characteristics of the fabricated GaAs Gunn diodes. The operating current, oscillation frequency, and output power of the fabricated GaAs Gunn diodes are presented as a function of the anode diameters. The operating current increases with anode diameters, whereas the oscillation frequency decreases. The higher oscillation frequency was obtained from 60 µm anode diameters of the fabricated Gunn GaAs diodes and higher power was obtained from 68 µm. Also, for application of the 94 GHz FMCW radar system, we have fabricated the 94 GHz waveguide VCO. From the fabricated GaAs Gunn diodes of anode diameter of 60 µm, we have obtained the improved VCO performance.

  9. Application of spherical diodes for megavoltage photon beams dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Barbés, Benigno, E-mail: bbarbes@unav.es [Servicio de Oncología Radioterápica, Clínica Universidad de Navarra, Avda. Pío XII, 36, E-31008 Pamplona, Navarra (Spain); Azcona, Juan D. [Department of Radiation Oncology, Stanford University, Stanford, California 94305 and Servicio de Oncología Radioterápica, Clínica Universidad de Navarra, Avda. Pío XII 36, E-31008 Pamplona, Navarra (Spain); Burguete, Javier [Departamento de Física y Matemática Aplicada, Facultad de Ciencias, Universidad de Navarra, Irunlarrea 1, E-31008 Pamplona, Navarra (Spain); Martí-Climent, Josep M. [Servicio de Medicina Nuclear, Clínica Universidad de Navarra, Avda. Pío XII 36, E-31008 Pamplona, Navarra (Spain)

    2014-01-15

    Purpose: External beam radiation therapy (EBRT) usually uses heterogeneous dose distributions in a given volume. Designing detectors for quality control of these treatments is still a developing subject. The size of the detectors should be small to enhance spatial resolution and ensure low perturbation of the beam. A high uniformity in angular response is also a very important feature in a detector, because it has to measure radiation coming from all the directions of the space. It is also convenient that detectors are inexpensive and robust, especially to performin vivo measurements. The purpose of this work is to introduce a new detector for measuring megavoltage photon beams and to assess its performance to measure relative dose in EBRT. Methods: The detector studied in this work was designed as a spherical photodiode (1.8 mm in diameter). The change in response of the spherical diodes is measured regarding the angle of incidence, cumulated irradiation, and instantaneous dose rate (or dose per pulse). Additionally, total scatter factors for large and small fields (between 1 × 1 cm{sup 2} and 20 × 20 cm{sup 2}) are evaluated and compared with the results obtained from some commercially available ionization chambers and planar diodes. Additionally, the over-response to low energy scattered photons in large fields is investigated using a shielding layer. Results: The spherical diode studied in this work produces a high signal (150 nC/Gy for photons of nominal energy of 15 MV and 160 for 6 MV, after 12 kGy) and its angular dependence is lower than that of planar diodes: less than 5% between maximum and minimum in all directions, and 2% around one of the axis. It also has a moderated variation with accumulated dose (about 1.5%/kGy for 15 MV photons and 0.7%/kGy for 6 MV, after 12 kGy) and a low variation with dose per pulse (±0.4%), and its behavior is similar to commercial diodes in total scatter factor measurements. Conclusions: The measurements of relative dose

  10. Diode Lasers used in Plastic Welding and Selective Laser Soldering - Applications and Products

    Science.gov (United States)

    Reinl, S.

    Aside from conventional welding methods, laser welding of plastics has established itself as a proven bonding method. The component-conserving and clean process offers numerous advantages and enables welding of sensitive assemblies in automotive, electronic, medical, human care, food packaging and consumer electronics markets. Diode lasers are established since years within plastic welding applications. Also, soft soldering using laser radiation is becoming more and more significant in the field of direct diode laser applications. Fast power controllability combined with a contactless temperature measurement to minimize thermal damage make the diode laser an ideal tool for this application. These advantages come in to full effect when soldering of increasingly small parts in temperature sensitive environments is necessary.

  11. Diode laser osteoperforation and its application to osteomyelitis treatment

    Science.gov (United States)

    Privalov, Valeriy A.; Krochek, Igor V.; Lappa, Alexander V.

    2001-10-01

    Laser osteoperforation, previously studied in experiment in rabbits at treatment for acute purulent osteomyelitis (Privalov V. et.al., SPIE Proc., v.3565., pp. 72-79), was applied in clinic to 36 patients with chronic purulent osteomyelitis and to 6 patients (children) with acute haematogenic osteomyelitis. Diode lasers of 805 and 980 nm wavelength were used. There was achieved full recovery in all acute cases, and stable remission in chronic cases during all the observation period (1 - 2.5 years).

  12. Interdigitated planar Schottky varactor diodes for tunable MMIC applications

    OpenAIRE

    Lucyszyn, Stepan; Green, Ged; Robertson, Ian D.

    1992-01-01

    Techniques are presented for scale modelling interdigitated Planar Schottky Varactor Diodes (PSVDs) using an equivalent circuit model. A selection of low cost GaAs devices, with variations in the finger width and number of anode fingers, have been fabricated, measured and accurately characterized - well into the millimetric frequency range. From the results, a number of useful design rules are presented for the optimal choice of interdigitated PSVD topography. With the use of these rules, a 2...

  13. Optimized high-power diode laser, laser arrays, and bars for pump applications

    Science.gov (United States)

    Hülsewede, R.; Schulze, H.; Sebastian, J.; Schröder, D.; Meusel, J.; Wolf, J.; Hennig, P.

    2009-02-01

    Broad area diode laser and diode laser bars are the most efficient light sources. In comparison to solid state laser or gas laser systems the over all beam quality of the diode laser is poor. Thus most application of diode laser bars is high efficient pumping of solid state lasers converting the beam quality and scaling the power of laser systems within the kW range. The pump efficiency and the beam coupling efficiency of the diode laser pumped systems has to be increased to meet the increasing laser market demands for reduced costs. JENOPTIK Diode Lab GmbH (JDL) has optimized their high power brilliance bars to enable reliable high power operation especially, for the 9xx nm wavelength range and low far field divergences. Superior reliability with long operation time of 13,000 hours and high power operation of 200 W are demonstrated for high power bars high filling factor mounted on passively cooled heat sinks. Smaller far field divergence at high power levels requires longer cavity length and higher efficiencies in the beam coupling needs requires lower filling factors. The new high brilliance bars and arrays with 20% filling factor are showing high power operation up to 95 W and a slow axis beam divergence of less than 8° (95% power content).

  14. Laser assisted die bending: a new application of high power diode lasers

    Science.gov (United States)

    Schuöcker, D.; Schumi, T.; Spitzer, O.; Bammer, F.; Schuöcker, G.; Sperrer, G.

    2015-02-01

    Nowadays high power lasers are mainly used for cutting of sheet metals, for welding, hardening and rapid prototyping. In the forming of sheet metals as bending or deep drawing lasers are not used. Nevertheless a few years ago a new application of high power lasers has been invented, where bending of materials that break at room temperature becomes possible by heating them along the bending edge with high power lasers thus allowing their treatment without cracks and rupture. For this purpose a large number of diode lasers are arranged in the bottom tool of a bending machine (a V-shaped die) which heat up the initially flat sheet metal during the bending process what is performed by pressing it into the die with a knife shaped upper tool where due to the laser heating the material is softened and thus cracks are avoided. For the technical realization of the new process of laser assisted die bending, modules equipped with numerous laser diodes and a total beam power of 2,5 kW are used. The light emitted by these modules enters a tool with a length of 15cm and is deflected towards the workpiece. By using ten of these modules with adjacent dies and by integrating those in a bending press a bending edge of sheet metals with a length of 1500mm can be realized. Such a bending press with laser assistance also needs energization with a power of practically 50kW, a respective water flow, a heat exchanger system and also a control for all functions of this system. Special measures have also been developed to avoid radiating of those tools that are not covered by a workpiece in the case of bending edges shorter than the full length of the bending tools whereas individual short circuiting of diode modules can be performed. Specific measures to ensure a safe operation without any harm to the operational person have been realized. Exploitation of the bending process has been carried out for titanium, where material thicknesses up to 3mm have been bent successfully.

  15. Advances in AlGaInN laser diode technology for defence, security and sensing applications

    Science.gov (United States)

    Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisnieski, P.; Czernecki, R.; Targowski, G.

    2016-10-01

    Laser diodes fabricated from the AlGaInN material system is an emerging technology for defence, security and sensing applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., 380nm, to the visible 530nm, by tuning the indium content of the laser GaInN quantum well, giving rise to new and novel applications including displays and imaging systems, free-space and underwater telecommunications and the latest quantum technologies such as optical atomic clocks and atom interferometry.

  16. A Compact Tunable Diode Laser Absorption Spectrometer to Monitor CO2 at 2.7 µm Wavelength in Hypersonic Flows

    Directory of Open Access Journals (Sweden)

    Raphäel Vallon

    2010-06-01

    Full Text Available Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship’s Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow.

  17. AlGaInN laser diode technology and systems for defence and security applications

    Science.gov (United States)

    Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lujca; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Scott; Kelly, Antony E.

    2015-10-01

    AlGaInN laser diodes is an emerging technology for defence and security applications such as underwater communications and sensing, atomic clocks and quantum information. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Thus AlGaInN laser diode technology is a key enabler for the development of new disruptive system level applications in displays, telecom, defence and other industries. Ridge waveguide laser diodes are fabricated to achieve single mode operation with optical powers up to 100mW with the 400-440nm wavelength range with high reliability. Visible free-space and underwater communication at frequencies up to 2.5GHz is reported using a directly modulated 422nm GaN laser diode. Low defectivity and highly uniform GaN substrates allow arrays and bars to be fabricated. High power operation operation of AlGaInN laser bars with up to 20 emitters have been demonstrated at optical powers up to 4W in a CS package with common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space or optical fibre system integration with a very small form-factor.

  18. Flow noise in sonar applications

    CERN Document Server

    Henke, Christian

    2016-01-01

    In this paper we present an investigation of flow noise in sonar applications. Based on a careful identification of the dominant coupling effects, the acoustic noise at the sensor position resulting from the turbulent wall pressure fluctuations is modelled with a system of hydrodynamic, bending and acoustic waves. We describe an analytical solution of the problem which is based on a coupled eigenfunction expansion method. Finally, it is demonstrated that the analytical solution describes the flow noise generation and propagation mechanisms of the considered sea trials.

  19. Fabrication and Characterisation of GaAs Gunn Diode Chips for Applications at 77 GHz in Automotive Industry

    OpenAIRE

    Hans Lüth; Mihail Ion Lepsa; Simone Montanari; Jürgen Stock; Arno Förster

    2006-01-01

    GaAs-based Gunn diodes with graded AlGaAs hot electron injector heterostructures have been developed under the special needs in automotive applications. The fabrication of the Gunn diode chips was based on total substrate removal and processing of integrated Au heat sinks. Especially, the thermal and RF behavior of the diodes have been analyzed by DC, impedance and S-parameter measurements. The electrical investigations have revealed the functionality of the hot electron injector. An optimize...

  20. Medical Applications of Space Light-Emitting Diode Technology--Space Station and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Whelan, H.T.; Houle, J.M.; Donohoe, D.L.; Bajic, D.M.; Schmidt, M.H.; Reichert, K.W.; Weyenberg, G.T.; Larson, D.L.; Meyer, G.A.; Caviness, J.A.

    1999-06-01

    Space light-emitting diode (LED) technology has provided medicine with a new tool capable of delivering light deep into tissues of the body, at wavelengths which are biologically optimal for cancer treatment and wound healing. This LED technology has already flown on Space Shuttle missions, and shows promise for wound healing applications of benefit to Space Station astronauts.

  1. The optical characterization of organometallic complex thin films by spectroscopic ellipsometry and photovoltaic diode application

    Energy Technology Data Exchange (ETDEWEB)

    Özaydın, C. [Batman University, Engineering Faculty, Department of Computer Eng., Batman (Turkey); Güllü, Ö., E-mail: omergullu@gmail.com [Batman University, Science and Art Faculty, Department of Physics, Batman (Turkey); Pakma, O. [Batman University, Science and Art Faculty, Department of Physics, Batman (Turkey); Ilhan, S. [Siirt University, Science and Art Faculty, Department of Chemistry, Siirt (Turkey); Akkılıç, K. [Dicle University, Education Faculty, Department of Physics Education, Diyarbakır (Turkey)

    2016-05-15

    Highlights: • Optical properties and thickness of the A novel organometallic complex (OMC) film were investigated by spectroscopic ellipsometry (SE). • Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated • This paper presents the I–V analysis of Au/OMC/n-Si MIS diode. • Current–voltage and photovoltaic properties of the diode were investigated. - Abstract: In this work, organometallic complex (OMC) films have been deposited onto glass or silicon substrates by spin coating technique and their photovoltaic application potential has been investigated. Optical properties and thickness of the film have been investigated by spectroscopic ellipsometry (SE). Also, transmittance spectrum has been taken by UV/vis spectrophotometer. The optical method has been used to determine the band gap value of the films. Also, Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated. Current–voltage and photovoltaic properties of the structure were investigated. The ideality factor (n) and barrier height (Φ{sub b}) values of the diode were found to be 2.89 and 0.79 eV, respectively. The device shows photovoltaic behavior with a maximum open-circuit voltage of 396 mV and a short circuit current of 33.8 μA under 300 W light.

  2. Application of well characterized e - beam evaporated WSe2 thin films in Schottky Barrier diodes

    Science.gov (United States)

    Patel, Mayurkumar M.

    The studies of semiconductor thin films and their junctions such as metal semiconductor junctions (Schottky Barriers) have received much attention due to their applications in various electronic and optoelectronic devices including high frequency switching device, Schottky barrier devices, solar cells etc. But, realization of any electronic device using a combination of bulk and thin film or all bulk or all thin film components essentially requires metallization of metal contacts for electrical signals to flow into and out of the device. Thus junction between two metals and metal-semiconductor is an integral part of the device without which communication to the external circuit components would not be possible. In this reference stable metalsemiconductor contacts of ohmic as well as rectifying nature are very much important from technological point of view. In both cases preparation of reliable and efficient metal contacts with high yield and stability is challenging task for devices operating at high frequencies when packing density is increased by many fold. Thus, the behavior of metal-semiconductor contacts at microscopic scale may be explored for the development of future technology. The subject matter of such contacts is well documented in many books with review of developments in the recent past. Earlier devices were prepared on the bulk elemental semiconductors as an active region which was then followed by crystalline/amorphous compound semiconductors in bulk as well as thin film forms like Solar cells, p-n junction diodes, Schottky barrier devices etc. in recent past. Normally bulk crystalline'or amorphous substrate is used to support device structure made from crystalline/amorphous bulk and thin film. However, to the best of author's knowledge no attempts have been made to study the devices prepared by depositing semiconductor thin film with thin metal film supported by a by a non-conducting glass substrate. For this purpose, studies were carried out on

  3. Uncertainty in velocity measurement based on diode-laser absorption in nonuniform flows.

    Science.gov (United States)

    Li, Fei; Yu, Xilong; Cai, Weiwei; Ma, Lin

    2012-07-10

    This work investigates the error caused by nonuniformities along the line-of-sight in velocity measurement using tunable diode-laser absorption spectroscopy (TDLAS). Past work has demonstrated TDLAS as an attractive diagnostic technique for measuring velocity, which is inferred from the Doppler shift of two absorption features using two crossing laser beams. However, because TDLAS is line-of-sight in nature, the obtained velocity is a spatially averaged value along the probing laser beams. As a result, nonuniformities in the flow can cause uncertainty in the velocity measurement. Therefore, it is the goal of this work to quantify the uncertainty caused by various nonuniformities typically encountered in practice, including boundary layer effects, the divergence/convergence of the flow, and the methods used to fit the Doppler shift. Systematic analyses are performed to quantify the uncertainty under various conditions, and case studies are reported to illustrate the usefulness of such analysis in interpreting experimental data obtained from a scramjet facility. We expect this work to be valuable for the design and optimization of TDLAS-based velocimetry, and also for the quantitative interpretation of the measurements.

  4. Application of Surface Plasmonics for Semiconductor Light-Emitting Diodes

    DEFF Research Database (Denmark)

    Fadil, Ahmed

    This thesis addresses the lack of an efficient semiconductor light source at green emission colours. Considering InGaN based quantum-well (QW) light-emitters and light-emitting diodes (LEDs), various ways of applying surface plasmonics and nano-patterning to improve the efficiency, are investigated....... By placing metallic thin films or nanoparticles (NPs) in the near-field of QW light-emitters, it is possible to improve their internal quantum efficiency (IQE) through the Purcell enhancement effect. It has been a general understanding that in order to achieve surface plasmon (SP) coupling with QWs...... is presented to obtain light extraction efficiency (LEE) improvement through nano-patterning, and IQE improvement through SP-QW coupling. Considering the fabrication process aspect, dry-etching damage on the semiconductor light-emitters from the nano-patterning is also addressed. Different ion-damage treatment...

  5. JENOPTIK diode lasers and bars optimized for high-power applications in the NIR range

    Science.gov (United States)

    Zorn, M.; Hülsewede, R.; Schulze, H.; Sebastian, J.; Hennig, P.; Schröder, D.

    2010-02-01

    Laser diodes and laser bars for the high-volume wavelength ranges at 808 nm and 940 nm are available in optimized design and high quality. However, a lot of other wavelengths in the NIR are needed for specialized applications also requiring high stability, reliability and a good efficiency with a good beam quality. An efficient adaptation of the laser diode design to optimize the laser performance at the customized wavelength is highly desirable. At JENOPTIK Diode Lab (JDL) we therefore focus on a flexible and competitive laser diode design resulting in a high output power and a high efficiency at reasonable production costs. Starting from excellent laser bars at 808 nm and 940 nm laser bars with emission wavelengths around 790 nm, 830 nm, 880nm (cw) and 940 nm (pulsed operation) are developed. For 792 nm a maximum output power of 90 W and an efficiency of 55 % has been achieved with an expected lifetime of more than 15000 hours. At 825 nm a maximum efficiency of 60 % and 60 W output power for more than 20.000 h with a high degree of polarization can be presented. Changing the quantum well material for 885 nm the output power reaches 125W with 63% efficiency also for more than 25.000 hours. Laser bars for pulsed applications (quasi-cw) at 940 nm result in an output power of 500 W with an efficiency of 60 %.

  6. AlGaInN laser diode technology for defence, security and sensing applications

    Science.gov (United States)

    Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lucja; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Scott; Kelly, Antony E.

    2014-10-01

    The latest developments in AlGaInN laser diode technology are reviewed for defence, security and sensing applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., i.e, 380nm, to the visible, i.e., 530nm, by tuning the indium content of the laser GaInN quantum well. Advantages of using Plasma assisted MBE (PAMBE) compared to more conventional MOCVD epitaxy to grow AlGaInN laser structures are highlighted. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of communications at high frequency (up to 2.5 Gbit/s) using a directly modulated 422nm Gallium-nitride (GaN) blue laser diode is reported. High power operation of AlGaInN laser diodes is demonstrated with a single chip, AlGaInN laser diode `mini-array' with a common p-contact configuration at powers up to 2.5W cw at 410nm. Low defectivity and highly uniform GaN substrates allow arrays and bars of nitride lasers to be fabricated. GaN laser bars of up to 5mm with 20 emitters, mounted in a CS mount package, give optical powers up to 4W cw at ~410nm with a common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space and/or fibre optic system integration within a very small form-factor.or.

  7. White Light Emitting Diode Development for General Illumination Applications

    Energy Technology Data Exchange (ETDEWEB)

    James Ibbetson

    2006-05-01

    This report contains a summary of technical achievements during a 3-year project aimed at developing the chip and packaging technology necessary to demonstrate efficient, high flux light-emitting diode (LED) arrays using Cree's gallium nitride/silicon carbide (GaN/SiC) LED technology as the starting point. Novel chip designs and fabrication processes are described that led to high power blue LEDs that achieved 310 mW of light output at 350 mA drive current, corresponding to quantum and wall plug efficiencies of 32.5% and 26.5%, respectively. When combined with phosphor, high power white LEDs with luminous output of 67 lumens and efficacy of 57 lumens per watt were also demonstrated. Advances in packaging technology are described that enabled compact, multi-chip white LED lamp modules with 800-1000 lumens output at efficacies of up to 55 lumens per watt. Lamp modules with junction-to-ambient thermal resistance as low as 1.7 C/watt have also been demonstrated.

  8. Ideal Diode Equation for Organic Heterojunctions. I. Derivation and Application

    Energy Technology Data Exchange (ETDEWEB)

    Giebink, Noel C; Wiederrecht, Gary P; Wasielewski, Michael R; Forrest, Stephen R.

    2010-10-04

    The current-voltage characteristics of organic heterojunctions (HJs) are often modeled using the generalized Shockley equation derived for inorganic diodes. However, since this description does not rigorously apply to organic semiconductor donor-acceptor (D-A) HJs, the extracted parameters lack a clear physical meaning. Here, we derive the current density-voltage (J-V) characteristic specifically for D-A HJ solar cells and show that it predicts the general dependence of dark current, open-circuit voltage (Voc) , and short-circuit current (Joc) on temperature and light intensity as well as the maximum Voc for a given D-A material pair. We propose that trap-limited recombination due to disorder at the D-A interface leads to the introduction of two temperature-dependent ideality factors and show that this describes the dark current of copper phthalocyanine/C60 and boron subphthalocyanine/C60 cells at low temperature, where fits to the generalized Shockley equation break down. We identify the polaron pair recombination rate as a key factor that determines the J-V characteristics in the dark and under illumination and provide direct measurements of this process in our companion paper II [N. C. Giebink, B. E. Lassiter, G. P. Wiederrecht, M. R. Wasielewski, and S. R. Forrest, Phys. Rev. B 82, 155306 (2010)]. These results provide a general physical framework for interpreting the J-V characteristics

  9. Adoption of Light-Emitting Diodes in Common Lighting Applications

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Mary [Navigant Consulting, Suwanee, GA (United States); Chwastyk, Dan [Navigant Consulting, Suwanee, GA (United States)

    2013-05-01

    Report estimating LED energy savings in nine applications where LEDs compete with traditional lighting sources such as incandescent, halogen, high-pressure sodium, and certain types of fluorescent. The analysis includes indoor lamp, indoor luminaire, and outdoor luminaire applications.

  10. Adoption of Light-Emitting Diodes in Common Lighting Applications

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Mary [Navigant, Chicago, IL (United States); Stober, Kelsey [Navigant, Chicago, IL (United States)

    2015-07-01

    Report estimating LED energy savings between 2012 and 2014 in 10 applications where LEDs competed with traditional lighting sources such as incandescent, halogen, high-pressure sodium, and fluorescent. The analysis includes indoor lamp, indoor luminaire, and outdoor luminaire applications.

  11. PERFORMANCE OPTIMIZATION OF THE DIODE-PUMPED SOLID-STATE LASER FOR SPACE APPLICATIONS

    Directory of Open Access Journals (Sweden)

    D. A. Arkhipov

    2015-11-01

    within 1 °С. Optical schematic diagram of the laser resonator keeps the laser beam divergence not exceeding a diffraction limit more than twice under a light pump power of 100 W. We have also shown that to increase the lasing efficiency, slab multilayer dielectric coatings made of SiO2 и ZrO2 should be used. Practical Relevance. We have proposed original design of the diode pumped solid-state laser module optimizing the generation and pump modes of solid-state lasers by the temperature stabilization technique for laser diode array and by compensation of the slab aberrations. The techniques are also applicable under space conditions; that is an important factor at developing the space-based lasers.

  12. Modeling of static and flowing-gas diode pumped alkali lasers

    Science.gov (United States)

    Barmashenko, Boris D.; Auslender, Ilya; Yacoby, Eyal; Waichman, Karol; Sadot, Oren; Rosenwaks, Salman

    2016-03-01

    Modeling of static and flowing-gas subsonic, transonic and supersonic Cs and K Ti:Sapphire and diode pumped alkali lasers (DPALs) is reported. A simple optical model applied to the static K and Cs lasers shows good agreement between the calculated and measured dependence of the laser power on the incident pump power. The model reproduces the observed threshold pump power in K DPAL which is much higher than that predicted by standard models of the DPAL. Scaling up flowing-gas DPALs to megawatt class power is studied using accurate three-dimensional computational fluid dynamics model, taking into account the effects of temperature rise and losses of alkali atoms due to ionization. Both the maximum achievable power and laser beam quality are estimated for Cs and K lasers. The performance of subsonic and, in particular, supersonic DPALs is compared with that of transonic, where supersonic nozzle and diffuser are spared and high power mechanical pump (needed for recovery of the gas total pressure which strongly drops in the diffuser), is not required for continuous closed cycle operation. For pumping by beams of the same rectangular cross section, comparison between end-pumping and transverse-pumping shows that the output power is not affected by the pump geometry, however, the intensity of the output laser beam in the case of transverse-pumped DPALs is strongly non-uniform in the laser beam cross section resulting in higher brightness and better beam quality in the far field for the end-pumping geometry where the intensity of the output beam is uniform.

  13. Ideal diode equation for organic heterojunctions. I. Derivation and application

    Energy Technology Data Exchange (ETDEWEB)

    Giebink, Noel C; Wiederrecht, Gary P; Wasielewski, Michael R; Forrest, Stephen R.

    2010-10-04

    The current-voltage characteristics of organic heterojunctions (HJs) are often modeled using the generalized Shockley equation derived for inorganic diodes. However, since this description does not rigorously apply to organic semiconductor donor-acceptor (D-A) HJs, the extracted parameters lack a clear physical meaning. Here, we derive the current density-voltage (J-V) characteristic specifically for D-A HJ solar cells and show that it predicts the general dependence of dark current, open-circuit voltage (V{sub oc} ) , and short-circuit current (J{sub sc} ) on temperature and light intensity as well as the maximum V{sub oc} for a given D-A material pair. We propose that trap-limited recombination due to disorder at the D-A interface leads to the introduction of two temperature-dependent ideality factors and show that this describes the dark current of copper phthalocyanine/C{sub 60} and boron subphthalocyanine/C{sub 60} cells at low temperature, where fits to the generalized Shockley equation break down. We identify the polaron pair recombination rate as a key factor that determines the J-V characteristics in the dark and under illumination and provide direct measurements of this process in our companion paper II [N. C. Giebink, B. E. Lassiter, G. P. Wiederrecht, M. R. Wasielewski, and S. R. Forrest, Phys. Rev. B 82, 155306 (2010)]. These results provide a general physical framework for interpreting the J-V characteristics and understanding the efficiency of both small molecule and polymer organic, planar and bulk HJ solar cells.

  14. Ideal diode equation for organic heterojunctions. I. Derivation and application

    Science.gov (United States)

    Giebink, N. C.; Wiederrecht, G. P.; Wasielewski, M. R.; Forrest, S. R.

    2010-10-01

    The current-voltage characteristics of organic heterojunctions (HJs) are often modeled using the generalized Shockley equation derived for inorganic diodes. However, since this description does not rigorously apply to organic semiconductor donor-acceptor (D-A) HJs, the extracted parameters lack a clear physical meaning. Here, we derive the current density-voltage (J-V) characteristic specifically for D-A HJ solar cells and show that it predicts the general dependence of dark current, open-circuit voltage (Voc) , and short-circuit current (Jsc) on temperature and light intensity as well as the maximum Voc for a given D-A material pair. We propose that trap-limited recombination due to disorder at the D-A interface leads to the introduction of two temperature-dependent ideality factors and show that this describes the dark current of copper phthalocyanine/ C60 and boron subphthalocyanine/ C60 cells at low temperature, where fits to the generalized Shockley equation break down. We identify the polaron pair recombination rate as a key factor that determines the J-V characteristics in the dark and under illumination and provide direct measurements of this process in our companion paper II [N. C. Giebink, B. E. Lassiter, G. P. Wiederrecht, M. R. Wasielewski, and S. R. Forrest, Phys. Rev. B 82, 155306 (2010)10.1103/PhysRevB.82.155306]. These results provide a general physical framework for interpreting the J-V characteristics and understanding the efficiency of both small molecule and polymer organic, planar and bulk HJ solar cells.

  15. InGaAs Quantum Well Grown on High-Index Surfaces for Superluminescent Diode Applications.

    Science.gov (United States)

    Li, Zhenhua; Wu, Jiang; Wang, Zhiming M; Fan, Dongsheng; Guo, Aqiang; Li, Shibing; Yu, Shui-Qing; Manasreh, Omar; Salamo, Gregory J

    2010-04-22

    The morphological and optical properties of In0.2Ga0.8As/GaAs quantum wells grown on various substrates are investigated for possible application to superluminescent diodes. The In0.2Ga0.8As/GaAs quantum wells are grown by molecular beam epitaxy on GaAs (100), (210), (311), and (731) substrates. A broad photoluminescence emission peak (~950 nm) with a full width at half maximum (FWHM) of 48 nm is obtained from the sample grown on (210) substrate at room temperature, which is over four times wider than the quantum well simultaneously grown on (100) substrate. On the other hand, a very narrow photoluminescence spectrum is observed from the sample grown on (311) with FWHM = 7.8 nm. The results presented in this article demonstrate the potential of high-index GaAs substrates for superluminescent diode applications.

  16. InGaAs Quantum Well Grown on High-Index Surfaces for Superluminescent Diode Applications

    Directory of Open Access Journals (Sweden)

    Wu Jiang

    2010-01-01

    Full Text Available Abstract The morphological and optical properties of In0.2Ga0.8As/GaAs quantum wells grown on various substrates are investigated for possible application to superluminescent diodes. The In0.2Ga0.8As/GaAs quantum wells are grown by molecular beam epitaxy on GaAs (100, (210, (311, and (731 substrates. A broad photoluminescence emission peak (~950 nm with a full width at half maximum (FWHM of 48 nm is obtained from the sample grown on (210 substrate at room temperature, which is over four times wider than the quantum well simultaneously grown on (100 substrate. On the other hand, a very narrow photoluminescence spectrum is observed from the sample grown on (311 with FWHM = 7.8 nm. The results presented in this article demonstrate the potential of high-index GaAs substrates for superluminescent diode applications.

  17. A diode laser-based velocimeter providing point measurements in unseeded flows using modulated filtered Rayleigh scattering (MFRS)

    Science.gov (United States)

    Jagodzinski, Jeremy James

    2007-12-01

    The development to date of a diode-laser based velocimeter providing point-velocity-measurements in unseeded flows using molecular Rayleigh scattering is discussed. The velocimeter is based on modulated filtered Rayleigh scattering (MFRS), a novel variation of filtered Rayleigh scattering (FRS), utilizing modulated absorption spectroscopy techniques to detect a strong absorption of a relatively weak Rayleigh scattered signal. A rubidium (Rb) vapor filter is used to provide the relatively strong absorption; alkali metal vapors have a high optical depth at modest vapor pressures, and their narrow linewidth is ideally suited for high-resolution velocimetry. Semiconductor diode lasers are used to generate the relatively weak Rayleigh scattered signal; due to their compact, rugged construction diode lasers are ideally suited for the environmental extremes encountered in many experiments. The MFRS technique utilizes the frequency-tuning capability of diode lasers to implement a homodyne detection scheme using lock-in amplifiers. The optical frequency of the diode-based laser system used to interrogate the flow is rapidly modulated about a reference frequency in the D2-line of Rb. The frequency modulation is imposed on the Rayleigh scattered light that is collected from the probe volume in the flow under investigation. The collected frequency modulating Rayleigh scattered light is transmitted through a Rb vapor filter before being detected. The detected modulated absorption signal is fed to two lock-in amplifers synchronized with the modulation frequency of the source laser. High levels of background rejection are attained since the lock-ins are both frequency and phase selective. The two lock-in amplifiers extract different Fourier components of the detected modulated absorption signal, which are ratioed to provide an intensity normalized frequency dependent signal from a single detector. A Doppler frequency shift in the collected Rayleigh scattered light due to a change

  18. Watt-level red-emitting diode lasers and modules for display applications

    Science.gov (United States)

    Paschke, Katrin; Blume, Gunnar; Feise, David; Pohl, Johannes; Sumpf, Bernd

    2016-02-01

    Red-emitting lasers for display applications require high output powers and a high visibility. We demonstrate diode lasers and modules in the red spectral range based on AlGaInP with optical output powers up to 1 W and a nearly diffraction limited beam. These high-luminance light sources based on tapered lasers are well suited for laser TVs and projectors for virtual reality simulators based on the flying spot technology. Additionally, we developed diode lasers with internal distributed Bragg reflector (DBR) surface gratings. These DBR tapered lasers and master-oscillator power-amplifiers based on DBR ridge-waveguide lasers and tapered amplifiers feature high power, single mode emission with coherence lengths up to several meters, which are suitable for the next-generation 3D displays based on holography.

  19. Bipolar one diode-one resistor integration for high-density resistive memory applications.

    Science.gov (United States)

    Li, Yingtao; Lv, Hangbing; Liu, Qi; Long, Shibing; Wang, Ming; Xie, Hongwei; Zhang, Kangwei; Huo, Zongliang; Liu, Ming

    2013-06-07

    Different from conventional unipolar-type 1D-1R RRAM devices, a bipolar-type 1D-1R memory device concept is proposed and successfully demonstrated by the integration of Ni/TiOx/Ti diode and Pt/HfO2/Cu bipolar RRAM cell to suppress the undesired sneak current in a cross-point array. The bipolar 1D-1R memory device not only achieves self-compliance resistive switching characteristics by the reverse bias current of the Ni/TiOx/Ti diode, but also exhibits excellent bipolar resistive switching characteristics such as uniform switching, satisfactory data retention, and excellent scalability, which give it high potentiality for high-density integrated nonvolatile memory applications.

  20. High power fiber coupled diode lasers for display and lighting applications

    Science.gov (United States)

    Drovs, Simon; Unger, Andreas; Dürsch, Sascha; Köhler, Bernd; Biesenbach, Jens

    2017-02-01

    The performance of diode lasers in the visible spectral range has been continuously improved within the last few years, which was mainly driven by the goal to replace arc lamps in cinema or home projectors. In addition, the availability of such high power visible diode lasers also enables new applications in the medical field, but also the usage as pump sources for other solid state lasers. This paper summarizes the latest developments of fiber coupled sources with output power from 1.4 W to 120 W coupled into 100 μm to 400 μm fibers in the spectral range around 405 nm and 640 nm. New developments also include the use of fiber coupled multi single emitter arrays at 450 nm, as well as very compact modules with multi-W output power.

  1. Fabrication and Characterisation of GaAs Gunn Diode Chips for Applications at 77 GHz in Automotive Industry

    Science.gov (United States)

    Förster, Arno; Stock, Jürgen; Montanari, Simone; Lepsa, Mihail Ion; Lüth, Hans

    2006-01-01

    GaAs-based Gunn diodes with graded AlGaAs hot electron injector heterostructures have been developed under the special needs in automotive applications. The fabrication of the Gunn diode chips was based on total substrate removal and processing of integrated Au heat sinks. Especially, the thermal and RF behavior of the diodes have been analyzed by DC, impedance and S-parameter measurements. The electrical investigations have revealed the functionality of the hot electron injector. An optimized layer structure could fulfill the requirements in adaptive cruise control (ACC) systems at 77 GHz with typical output power between 50 and 90 mW.

  2. Synthesis and optical properties of cadmium selenide quantum dots for white light-emitting diode application

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xianmei; Wang, Yilin; Gule, Teri; Luo, Qiang [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China); Zhou, Liya, E-mail: zhouliyatf@163.com [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China); Gong, Fuzhong [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 53000 (China)

    2013-03-15

    Highlights: ► Stable CdSe QDs were synthesized by the one-step and two-level process respectively. ► The fabricated white LEDs show good white balance. ► CdSe QDs present well green to yellow band luminescence. ► CdSe QDs displayed a broad excitation band. - Abstract: Yellow light-emitting cadmium selenide quantum dots were synthesized using one-step and two-step methods in an aqueous medium. The structural luminescent properties of these quantum dots were investigated. The obtained cadmium selenide quantum dots displayed a broad excitation band suitable for blue or near-ultraviolet light-emitting diode applications. White light-emitting diodes were fabricated by coating the cadmium selenide samples onto a 460 nm-emitting indium gallium nitrite chip. Both samples exhibited good white balance. Under a 20 mA working current, the white light-emitting diode fabricated via the one-step and two-step methods showed Commission Internationale de l’Éclairage coordinates at (0.27, 0.23) and (0.27, 0.33), respectively, and a color rendering index equal to 41 and 37, respectively. The one-step approach was simpler, greener, and more effective than the two-step approach. The one-step approach can be enhanced by combining cadmium selenide quantum dots with proper phosphors.

  3. Reverse Current Characteristics of InP Gunn Diodes for W-Band Waveguide Applications.

    Science.gov (United States)

    Kim, Hyun-Seok; Heo, Jun-Woo; Chol, Seok-Gyu; Ko, Dong-Sik; Rhee, Jin-Koo

    2015-07-01

    InP is considered as the most promising material for millimeter-wave laser-diode applications owing to its superior noise performance and wide operating frequency range of 75-110 GHz. In this study, we demonstrate the fabrication of InP Gunn diodes with a current-limiting structure using rapid thermal annealing to modulate the potential height formed between an n-type InP active layer and a cathode contact. We also explore the reverse current characteristics of the InP Gunn diodes. Experimental results indicate a maximum anode current and an oscillation frequency of 200 mA and 93.53 GHz, respectively. The current-voltage characteristics are modeled by considering the Schottky and ohmic contacts, work function variations, negative differential resistance (NDR), and tunneling effect. Although no direct indication of the NDR is observed, the simulation results match the measured data well. The modeling results show that the NDR effect is always present but is masked because of electron emission across the shallow Schottky barrier.

  4. Fluorescent SiC and its application to white light-emitting diodes*

    Institute of Scientific and Technical Information of China (English)

    Satoshi Kamiyama; Motoaki Iwaya; Tetsuya Takeuchi; Isamu Akasaki; Mikael Syv(a)j(a)rvi; Rositza Yakimova

    2011-01-01

    Fluorescent-SiC (f-SiC), which contains donor and acceptor impurities with optimum concentrations,has high conversion efficiency from NUV to visible light caused by donor-acceptor-pair (DAP) recombination.This material can be used as a substrate for a nearUV light-emitting diode (LED) stack, and leads to monolithic white LED device with suitable spectral property for general lighting applications. In this paper, we describe basic technologies of the white LED, such as optical properties of f-SiC substrate, and epitaxial growth of NUV stack on the f-SiC substrate.

  5. Custom single-photon avalanche diode with integrated front-end for parallel photon timing applications.

    Science.gov (United States)

    Cammi, C; Panzeri, F; Gulinatti, A; Rech, I; Ghioni, M

    2012-03-01

    Emerged as a solid state alternative to photo multiplier tubes (PMTs), single-photon avalanche diodes (SPADs) are nowadays widely used in the field of single-photon timing applications. Custom technology SPADs assure remarkable performance, in particular a 10 counts/s dark count rate (DCR) at low temperature, a high photon detection efficiency (PDE) with a 50% peak at 550 nm and a 30 ps (full width at half maximum, FWHM) temporal resolution, even with large area devices, have been obtained. Over the past few years, the birth of novel techniques of analysis has led to the parallelization of the measurement systems and to a consequent increasing demand for the development of monolithic arrays of detectors. Unfortunately, the implementation of a multidimensional system is a challenging task from the electrical point of view; in particular, the avalanche current pick-up circuit, used to obtain the previously reported performance, has to be modified in order to enable high parallel temporal resolution, while minimizing the electrical crosstalk probability between channels. In the past, the problem has been solved by integrating the front-end electronics next to the photodetector, in order to reduce the parasitic capacitances and consequently the filtering action on the current signal of the SPAD, leading to an improvement of the timing jitter at higher threshold. This solution has been implemented by using standard complementary metal-oxide-semiconductor (CMOS) technologies, which, however, do not allow a complete control on the SPAD structure; for this reason the intrinsic performance of CMOS SPADs, such as DCR, PDE, and afterpulsing probability, are worse than those attainable with custom detectors. In this paper, we propose a pixel architecture, which enables the development of custom SPAD arrays in which every channel maintains the performance of the best single photodetector. The system relies on the integration of the timing signal pick-up circuit next to the

  6. Computer modeling characterization, and applications of Gallium Arsenide Gunn diodes in radiation environments

    Energy Technology Data Exchange (ETDEWEB)

    El- Basit, Wafaa Abd; El-Ghanam, Safaa Mohamed; Kamh, Sanaa Abd El-Tawab [Electronics Research Laboratory, Physics Department, Faculty of Women for Arts, Science and Education, Ain-Shams University, Cairo (Egypt); Abdel-Maksood, Ashraf Mosleh; Soliman, Fouad Abd El-Moniem Saad [Nuclear Materials Authority, Cairo (Egypt)

    2016-10-15

    The present paper reports on a trial to shed further light on the characterization, applications, and operation of radar speed guns or Gunn diodes on different radiation environments of neutron or γ fields. To this end, theoretical and experimental investigations of microwave oscillating system for outer-space applications were carried out. Radiation effects on the transient parameters and electrical properties of the proposed devices have been studied in detail with the application of computer programming. Also, the oscillation parameters, power characteristics, and bias current were plotted under the influence of different γ and neutron irradiation levels. Finally, shelf or oven annealing processes were shown to be satisfactory techniques to recover the initial characteristics of the irradiated devices.

  7. Computer Modeling, Characterization, and Applications of Gallium Arsenide Gunn Diodes in Radiation Environments

    Directory of Open Access Journals (Sweden)

    Wafaa Abd El-Basit

    2016-10-01

    Full Text Available The present paper reports on a trial to shed further light on the characterization, applications, and operation of radar speed guns or Gunn diodes on different radiation environments of neutron or γ fields. To this end, theoretical and experimental investigations of microwave oscillating system for outer-space applications were carried out. Radiation effects on the transient parameters and electrical properties of the proposed devices have been studied in detail with the application of computer programming. Also, the oscillation parameters, power characteristics, and bias current were plotted under the influence of different γ and neutron irradiation levels. Finally, shelf or oven annealing processes were shown to be satisfactory techniques to recover the initial characteristics of the irradiated devices.

  8. Uncertainty in velocity measurement based on diode-laser absorption in nonuniform flows

    OpenAIRE

    Li, Fei; Yu, XiLong; Cai, Weiwei; Ma, Lin

    2012-01-01

    This work investigates the error caused by nonuniformities along the line-of-sight in velocity measurement using tunable diode-laser absorption spectroscopy (TDLAS). Past work has demonstrated TDLAS as an attractive diagnostic technique for measuring velocity, which is inferred from the Doppler shift of two absorption features using two crossing laser beams. However, because TDLAS is line-of-sight in nature, the obtained velocity is a spatially averaged value along the probing laser beams. As...

  9. Membranes for Redox Flow Battery Applications

    OpenAIRE

    Maria Skyllas-Kazacos; Aishwarya Parasuraman; Tuti Mariana Lim; Suminto Winardi; Helen Prifti

    2012-01-01

    The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. Th...

  10. Flow Sharing Systems for Mobile Applications

    DEFF Research Database (Denmark)

    Andersen, T. O.; Hansen, M. R.; Conrad, Finn

    2002-01-01

    This contribution reports about some analytical and simulation/experimental studies carried out on different flow control systems for mobile applications with respect to their ability to do flow sharing. All systems have two parallel actuators and are considered regarding functionality...

  11. Nanoporous silicon tubes: the role of geometry in nanostructure formation and application to light emitting diodes

    Science.gov (United States)

    Vukajlović Pleština, Jelena; Đerek, Vedran; Francaviglia, Luca; Amaduzzi, Francesca; Potts, Heidi; Ivanda, Mile; Morral, Anna Fontcuberta i.

    2017-07-01

    Obtaining light emission from silicon has been the holy grail of optoelectronics over the last few decades. One of the most common methods for obtaining light emission from silicon is to reduce it to a nanoscale structure, for example by producing porous silicon. Here, we present a method for the large-area fabrication of porous silicon microtubes by the stain etching of silicon micropillar arrays. We explain and model how the formation of the microtubes is influenced by the morphology of the substrate, especially the concave or convex character of the 3D features. Light emission is demonstrated at the micro- and nanoscale respectively by photo- and cathodoluminescence. Finally, we demonstrate a 0.55 cm2 device that can work as a photodetector with 2.3% conversion efficiency under one sun illumination, and also as a broadband light emitting diode, illustrating the applicability of our results for optoelectronic applications.

  12. Organic semiconductor heterojunctions and its application in organic light-emitting diodes

    CERN Document Server

    Ma, Dongge

    2017-01-01

    This book systematically introduces the most important aspects of organic semiconductor heterojunctions, including the basic concepts and electrical properties. It comprehensively discusses the application of organic semiconductor heterojunctions as charge injectors and charge generation layers in organic light-emitting diodes (OLEDs). Semiconductor heterojunctions are the basis for constructing high-performance optoelectronic devices. In recent decades, organic semiconductors have been increasingly used to fabricate heterojunction devices, especially in OLEDs, and the subject has attracted a great deal of attention and evoked many new phenomena and interpretations in the field. This important application is based on the low dielectric constant of organic semiconductors and the weak non-covalent electronic interactions between them, which means that they easily form accumulation heterojunctions. As we know, the accumulation-type space charge region is highly conductive, which is an important property for high...

  13. Light extraction from organic light-emitting diodes for lighting applications by sand-blasting substrates.

    Science.gov (United States)

    Chen, Shuming; Kwok, Hoi Sing

    2010-01-04

    Light extraction from organic light-emitting diodes (OLEDs) by scattering the light is one of the effective methods for large-area lighting applications. In this paper, we present a very simple and cost-effective method to rough the substrates and hence to scatter the light. By simply sand-blasting the edges and back-side surface of the glass substrates, a 20% improvement of forward efficiency has been demonstrated. Moreover, due to scattering effect, a constant color over all viewing angles and uniform light pattern with Lambertian distribution has been obtained. This simple and cost-effective method may be suitable for mass production of large-area OLEDs for lighting applications.

  14. Fabrication and Characterization of n-AlGaAs/GaAs Schottky Diode for Rectenna Device Application

    Science.gov (United States)

    Parimon, Norfarariyanti; Mustafa, Farahiyah; Manaf Hashim, Abdul; Fadzli Abd Rahman, Shaharin; Rahman, Abdul Rahim Abdul; Nizam Osman, Mohd

    2011-02-01

    Schottky diode was designed and fabricated on n-AlGaAs/GaAs high electron mobility transistor (HEMT) structure for rectenna device application. Rectenna is one of the most potential devices to form the wireless power supply which is really good at converting microwaves to DC. The processing steps used in the fabrication of Schottky diode were the conventional steps used in standard GaAs processing. Current-voltage (I-V) measurements showed that the device had rectifying properties with a barrier height of 0.5468 eV for Ni/Au metallization. The fabricated Schottky diode detected RF signals and the cut-off frequency up to 20 GHz was estimated in direct injection experiments. These preliminary results will provide a breakthrough for the direct integration with antenna towards realization of rectenna device application.

  15. Fabrication and Characterization of n-AlGaAs/GaAs Schottky Diode for Rectenna Device Application

    Energy Technology Data Exchange (ETDEWEB)

    Parimon, Norfarariyanti; Mustafa, Farahiyah; Hashim, Abdul Manaf; Rahman, Shaharin Fadzli Abd; Rahman, Abdul Rahim Abdul [Material Innovations and Nanoelectronics Research Group, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Osman, Mohd Nizam, E-mail: manaf@fke.utm.my [Telekom Research and Development, TM Innovation Centre, 63000 Cyberjaya (Malaysia)

    2011-02-15

    Schottky diode was designed and fabricated on n-AlGaAs/GaAs high electron mobility transistor (HEMT) structure for rectenna device application. Rectenna is one of the most potential devices to form the wireless power supply which is really good at converting microwaves to DC. The processing steps used in the fabrication of Schottky diode were the conventional steps used in standard GaAs processing. Current-voltage (I-V) measurements showed that the device had rectifying properties with a barrier height of 0.5468 eV for Ni/Au metallization. The fabricated Schottky diode detected RF signals and the cut-off frequency up to 20 GHz was estimated in direct injection experiments. These preliminary results will provide a breakthrough for the direct integration with antenna towards realization of rectenna device application.

  16. A study of the electrical properties of self-biased channel MOS diodes for solar-cell applications

    Directory of Open Access Journals (Sweden)

    Tsugutomo Kudoh

    2017-01-01

    Full Text Available We propose two types of low-cost, low-loss diodes as alternatives to Schottky barrier diodes (SBDs for use as bypass diodes connected in parallel with solar-cell panels. Both of our proposed devices are self-biasing channel MOS diodes consisting of an n-channel MOS structure that features three-terminal operation combined with a DMOS cell structure exploiting self-biasing effects. By reducing the threshold voltage of the MOS gate, these devices feature lower on-voltages and lower rates of growth in the reverse leakage current with increasing temperature, thus preventing thermal runaway. To investigate the properties of our devices, we used a device simulator to analyze their performance as bypass diodes for a solar-cell panel. Our results indicate that when a shadow partially covers the cell, the current flowing on the load side of the solar-cell panel is about 50% larger than that observed for a Cr SBD, indicating the potential for significantly improved performance.

  17. Amplitude-stabilized frequency-modulated laser diode and its interferometric sensing applications.

    Science.gov (United States)

    Takahashi, Y; Yoshino, T; Ohde, N

    1997-08-20

    A direct frequency-modulated (FM) laser diode light source without light power variation is developed. The amplitude variation of the FM laser diode is compensated by means of a feedback system with use of a superluminescent diode as an external light power controller. Output power greater than 1 mW is obtained at the modulation frequency to 5 kHz with a >10 stabilization factor. By use of the amplitude-stabilized FM laser diode, we measured subfringes with high accuracy in FM continuous wave interferometry, increased the dynamic range of the displacement measurement, and improved the stabilization factor in the laser diode feedback interferometer.

  18. Duality based optical flow algorithms with applications

    DEFF Research Database (Denmark)

    Rakêt, Lars Lau

    We consider the popular TV-L1 optical flow formulation, and the so-called duality based algorithm for minimizing the TV-L1 energy. The original formulation is extended to allow for vector valued images, and minimization results are given. In addition we consider different definitions of total...... variation regularization, and related formulations of the optical flow problem that may be used with a duality based algorithm. We present a highly optimized algorithmic setup to estimate optical flows, and give five novel applications. The first application is registration of medical images, where X......-ray images of different hands, taken using different imaging devices are registered using a TV-L1 optical flow algorithm. We propose to regularize the input images, using sparsity enhancing regularization of the image gradient to improve registration results. The second application is registration of 2D...

  19. Duality based optical flow algorithms with applications

    DEFF Research Database (Denmark)

    Rakêt, Lars Lau

    We consider the popular TV-L1 optical flow formulation, and the so-called duality based algorithm for minimizing the TV-L1 energy. The original formulation is extended to allow for vector valued images, and minimization results are given. In addition we consider different definitions of total...... variation regularization, and related formulations of the optical flow problem that may be used with a duality based algorithm. We present a highly optimized algorithmic setup to estimate optical flows, and give five novel applications. The first application is registration of medical images, where X......-ray images of different hands, taken using different imaging devices are registered using a TV-L1 optical flow algorithm. We propose to regularize the input images, using sparsity enhancing regularization of the image gradient to improve registration results. The second application is registration of 2D...

  20. Application of GaN-based ultraviolet-C light emitting diodes--UV LEDs--for water disinfection.

    Science.gov (United States)

    Würtele, M A; Kolbe, T; Lipsz, M; Külberg, A; Weyers, M; Kneissl, M; Jekel, M

    2011-01-01

    GaN-based ultraviolet-C (UV-C) light emitting diodes (LEDs) are of great interest for water disinfection. They offer significant advantages compared to conventional mercury lamps due to their compact form factor, low power requirements, high efficiency, non-toxicity, and overall robustness. However, despite the significant progress in the performance of semiconductor based UV LEDs that has been achieved in recent years, these devices still suffer from low emission power and relatively short lifetimes. Even the best UV LEDs exhibit external quantum efficiencies of only 1-2%. The objective of this study was to investigate the suitability of GaN-based UV LEDs for water disinfection. The investigation included the evaluation of the performance characteristics of UV LEDs at different operating conditions as well as the design of a UV LED module in view of the requirements for water treatment applications. Bioanalytical testing was conducted using Bacillus subtilis spores as test organism and UV LED modules with emission wavelengths of 269 nm and 282 nm. The results demonstrate the functionality of the developed UV LED disinfection modules. GaN-based UV LEDs effectively inactivated B. subtilis spores during static and flow-through tests applying varying water qualities. The 269 nm LEDs reached a higher level of inactivation than the 282 nm LEDs for the same applied fluence. The lower inactivation achieved by the 282 nm LEDs was compensated by their higher photon flux. First flow-through tests indicate a linear correlation between inactivation and fluence, demonstrating a well designed flow-through reactor. With improved light output and reduced costs, GaN-based UV LEDs can provide a promising alternative for decentralised and mobile water disinfection systems. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Beam Profile Improvement of a High-Power Diode Laser Stack for Optoacoustic Applications

    Science.gov (United States)

    Sánchez, Miguel; Rodríguez, Sergio; Leggio, Luca; Gawali, Sandeep; Gallego, Daniel; Lamela, Horacio

    2017-04-01

    Recent advances in high-power diode lasers (HPDLs) technology allow their use as potential sources for optoacoustic (OA) applications, due to their high repetition rates (a few kHz), low costs and sizes. However, some OA applications require pulse energies in the order of mJ that cannot be provided by the only HPDLs (several μJ). The employment of diode laser bars (DLBs) and stacks (DLSs) significantly increases the energy per pulse up to several mJ, but they require more optical elements for collimation in fast and slow axes. In this work, we show an 808 nm DLS emitting optical nanosecond pulses with currents of ˜ 200 A and supplied by a customized current driver. We only collimate the beam in the fast axis by disposing the core of 200 μm optical fibers as collimating lenses along each bar of the stack, and we discuss the improvement of the beam profile. The results demonstrate that the beam profile is notably improved with the optical fiber lenses, and a 6.4 mm × 4.3 mm light spot is obtained by using a conventional focusing lens. Measurements report a total energy per pulse of 630 μJ in the spot, considering a pulse width of 850 ns and a repetition rate of 1 kHz. Finally, we focus the light spot into an absorbing inclusion (graphene oxide) hosted in a semi-transparent phantom to generate and detect high OA signals ({˜ }355 mV_{pp}). The results achieved demonstrate the capability of our DLS system to be applied in multispectral OA systems with final application in OA endoscopy and microscopy.

  2. Flow cytometry: basic principles and applications.

    Science.gov (United States)

    Adan, Aysun; Alizada, Günel; Kiraz, Yağmur; Baran, Yusuf; Nalbant, Ayten

    2017-03-01

    Flow cytometry is a sophisticated instrument measuring multiple physical characteristics of a single cell such as size and granularity simultaneously as the cell flows in suspension through a measuring device. Its working depends on the light scattering features of the cells under investigation, which may be derived from dyes or monoclonal antibodies targeting either extracellular molecules located on the surface or intracellular molecules inside the cell. This approach makes flow cytometry a powerful tool for detailed analysis of complex populations in a short period of time. This review covers the general principles and selected applications of flow cytometry such as immunophenotyping of peripheral blood cells, analysis of apoptosis and detection of cytokines. Additionally, this report provides a basic understanding of flow cytometry technology essential for all users as well as the methods used to analyze and interpret the data. Moreover, recent progresses in flow cytometry have been discussed in order to give an opinion about the future importance of this technology.

  3. High-performance GaSb laser diodes and diode arrays in the 2.1-3.3 micron wavelength range for sensing and defense applications

    Science.gov (United States)

    Dvinelis, Edgaras; TrinkÅ«nas, Augustinas; Greibus, Mindaugas; Kaušylas, Mindaugas; Žukauskas, Tomas; Å imonytÄ--, Ieva; Songaila, RamÅ«nas; Vizbaras, Augustinas; Vizbaras, Kristijonas

    2015-01-01

    Mid-infrared spectral region (2-4 μm) is gaining significant attention recently due to the presence of numerous enabling applications in the field of gas sensing, medical, and defense applications. Gas sensing in this spectral region is attractive due to the presence of numerous absorption lines for such gases as methane, ethane, ozone, carbon dioxide, carbon monoxide, etc. Sensing of the mentioned gas species is of particular importance for applications such as atmospheric LIDAR, petrochemical industry, greenhouse gas monitoring, etc. Defense applications benefit from the presence of covert atmospheric transmission window in the 2.1-2.3 micron band which is more eye-safe and offers less Rayleigh scattering than the conventional atmospheric windows in the near-infrared. Major requirement to enable these application is the availability of high-performance, continuous-wave laser sources in this window. Type-I GaSb-based laser diodes are ideal candidates for these applications as they offer direct emission possibility, high-gain and continuous wave operation. Moreover, due to the nature of type-I transition, these devices have a characteristic low operation voltage, which results in very low input powers and high wall-plug efficiency. In this work, we present recent results of 2 μm - 3.0 μm wavelength room-temperature CW light sources based on type-I GaSb developed at Brolis Semiconductors. We discuss performance of defense oriented high-power multimode laser diodes with superluminescent gain chips will be presented.

  4. A Compact Tunable Diode Laser Absorption Spectrometer to Monitor CO2 at 2.7 μm Wavelength in Hypersonic Flows

    Science.gov (United States)

    Vallon, Raphäel; Soutadé, Jacques; Vérant, Jean-Luc; Meyers, Jason; Paris, Sébastien; Mohamed, Ajmal

    2010-01-01

    Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship’s Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow. PMID:22219703

  5. A compact tunable diode laser absorption spectrometer to monitor CO2 at 2.7 μm wavelength in hypersonic flows.

    Science.gov (United States)

    Vallon, Raphäel; Soutadé, Jacques; Vérant, Jean-Luc; Meyers, Jason; Paris, Sébastien; Mohamed, Ajmal

    2010-01-01

    Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship's Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow.

  6. Fabrication and Characterisation of GaAs Gunn Diode Chips for Applications at 77 GHz in Automotive Industry

    Directory of Open Access Journals (Sweden)

    Hans Lüth

    2006-04-01

    Full Text Available GaAs-based Gunn diodes with graded AlGaAs hot electron injectorheterostructures have been developed under the special needs in automotive applications.The fabrication of the Gunn diode chips was based on total substrate removal andprocessing of integrated Au heat sinks. Especially, the thermal and RF behavior of thediodes have been analyzed by DC, impedance and S-parameter measurements. Theelectrical investigations have revealed the functionality of the hot electron injector. Anoptimized layer structure could fulfill the requirements in adaptive cruise control (ACCsystems at 77 GHz with typical output power between 50 and 90 mW.

  7. Developing Quantum Dot Phosphor-Based Light-Emitting Diodes for Aviation Lighting Applications

    Directory of Open Access Journals (Sweden)

    Fengbing Wu

    2012-01-01

    Full Text Available We have investigated the feasibility of employing quantum dot (QD phosphor-based light-emitting diodes (LEDs in aviation applications that request Night Vision Imaging Systems (NVIS compliance. Our studies suggest that the emerging QD phosphor-based LED technology could potentially be superior to conventional aviation lighting technology by virtue of the marriage of tight spectral control and broad wavelength tunability. This largely arises from the fact that the optical properties of semiconductor nanocrystal QDs can be tailored by varying the nanocrystal size without any compositional changes. It is envisioned that the QD phosphor-based LEDs hold great potentials in cockpit illumination, back light sources of monitor screens, as well as the LED indicator lights of aviation panels.

  8. Luminescent Tungsten(VI) Complexes: Photophysics and Applicability to Organic Light-Emitting Diodes and Photocatalysis.

    Science.gov (United States)

    Yeung, Kwan-Ting; To, Wai-Pong; Sun, Chenyue; Cheng, Gang; Ma, Chensheng; Tong, Glenna So Ming; Yang, Chen; Che, Chi-Ming

    2017-01-02

    The synthesis, excited-state dynamics, and applications of two series of air-stable luminescent tungsten(VI) complexes are described. These tungsten(VI) complexes show phosphorescence in the solid state and in solutions with emission quantum yields up to 22 % in thin film (5 % in mCP) at room temperature. Complex 2 c, containing a 5,7-diphenyl-8-hydroxyquinolinate ligand, displays prompt fluorescence (blue-green) and phosphorescence (red) of comparable intensity, which could be used for ratiometric luminescent sensing. Solution-processed organic light-emitting diodes (OLEDs) based on 1 d showed a stable yellow emission with an external quantum efficiency (EQE) and luminance up to 4.79 % and 1400 cd m(-2) respectively. These tungsten(VI) complexes were also applied in light-induced aerobic oxidation reactions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Evaluation of inorganic and organic light-emitting diode displays for signage application

    Science.gov (United States)

    Sharma, Pratibha; Kwok, Harry

    2006-08-01

    High-brightness, inorganic light-emitting diodes (LEDs) have been successfully utilized for edge-lighting of large displays for signage. Further interest in solid-state lighting technology has been fueled with the emergence of small molecule and polymer-based organic light-emitting diodes (OLEDs). In this paper, edgelit inorganic LED-based displays and state-of-the-art OLED-based displays are evaluated on the basis of electrical and photometric measurements. The reference size for a signage system is assumed to be 600 mm x 600mm based on the industrial usage. With the availability of high power light-emitting diodes, it is possible to develop edgelit signage systems of the standard size. These displays possess an efficacy of 18 lm/W. Although, these displays are environmentally friendly and efficient, they suffer from some inherent limitations. Homogeneity of displays, which is a prime requirement for illuminated signs, is not accomplished. A standard deviation of 3.12 lux is observed between the illuminance values on the surface of the display. In order to distribute light effectively, reflective gratings are employed. Reflective gratings aid in reducing the problem but fail to eliminate it. In addition, the overall cost of signage is increased by 50% with the use of these additional components. This problem can be overcome by the use of a distributed source of light. Hence, the organic-LEDs are considered as a possible contender. In this paper, we experimentally determine the feasibility of using OLEDs for signage applications and compare their performance with inorganic LEDs. Passive matrix, small-molecule based, commercially available OLEDs is used. Design techniques for implementation of displays using organic LEDs are also discussed. It is determined that tiled displays based on organic LEDs possess better uniformity than the inorganic LED-based displays. However, the currently available OLEDs have lower light-conversion efficiency and higher costs than the

  10. Application of mid-infrared tuneable diode laser absorption spectroscopy to plasma diagnostics: a review

    Energy Technology Data Exchange (ETDEWEB)

    Roepcke, J [INP-Greifswald, 17489 Greifswald, Friedrich-Ludwig-Jahn-Str. 19 (Germany); Lombardi, G [CNRS LIMHP, Universite Paris XIII, 99, av. J.B. Clement, 93430 Villetaneuse (France); Rousseau, A [Laboratoire de Physique et Technologie des Plasmas, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Davies, P B [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2006-11-01

    Within the last decade mid-infrared absorption spectroscopy over a region from 3 to 17{mu}m and based on tuneable lead salt diode lasers, often called tuneable diode laser absorption spectroscopy or TDLAS, has progressed considerably as a powerful diagnostic technique for in situ studies of the fundamental physics and chemistry in molecular plasmas. The increasing interest in processing plasmas containing hydrocarbons, fluorocarbons, organo-silicon and boron compounds has led to further applications of TDLAS because most of these compounds and their decomposition products are infrared active. TDLAS provides a means of determining the absolute concentrations of the ground states of stable and transient molecular species, which is of particular importance for the investigation of reaction kinetic phenomena. Information about gas temperature and population densities can also be derived from TDLAS measurements. A variety of free radicals and molecular ions have been detected by TDLAS. Since plasmas with molecular feed gases are used in many applications such as thin film deposition, semiconductor processing, surface activation and cleaning, and materials and waste treatment, this has stimulated the adaptation of infrared spectroscopic techniques to industrial requirements. The recent development of quantum cascade lasers (QCLs) offers an attractive new option for the monitoring and control of industrial plasma processes. The aim of the present paper is threefold: (i) to review recent achievements in our understanding of molecular phenomena in plasmas (ii) to report on selected studies of the spectroscopic properties and kinetic behaviour of radicals and (iii) to describe the current status of advanced instrumentation for TDLAS in the mid-infrared.

  11. A Novel Type of Tri-Colour Light-Emitting-Diode-Based Spectrometric Detector for Low-Budget Flow-Injection Analysis

    Directory of Open Access Journals (Sweden)

    Nataša Gros

    2007-02-01

    Full Text Available In this paper we describe a low-cost spectrometric detector that can be easily assembled in a laboratory for less than €80 with a minimal number of optical components and which has proved sensitive and flexible enough for real-life applications. The starting point for the idea to construct this small, compact low-cost spectrometric detector was the decision to use a tri-colour light-emitting diode (LED of the red-green-blue (RGB type as a light source with the objective of achieving some flexibility in the selection of the wavelength (430 nm, 565 nm, 625 nm but avoiding the use of optical fibres. Due to the dislocation of the emitters of the different coloured light, the tri-colour LED-based detector required an optical geometry that differs from those that are described in literature. The proposed novel geometry, with a coil-type glass flow-through cell with up to four ascending turns, proved useful and fit for the purpose. The simplicity of the device means it requires a minimal number of optical components, i.e., only a tri-colour LED and a photoresistor. In order to make a flow-injection analysis (FIA with the spectrometric detector even more accessible for those with a limited budget, we additionally describe a low-cost simplified syringe-pump- based FIA set-up (€625, the assembling of which requires no more than basic technical facilities. We used such a set-up to test the performance of the proposed spectrometric detector for flow-injection analyses. The tests proved its suitability for real-life applications. The design procedures are also described.

  12. Laser Applications in Flow Diagnostics

    Science.gov (United States)

    1988-10-01

    sampling system and is governed by the nuances of sampling theory. If the wavefront is undersampled, the resulting data can be Plagued with... Albert , C., "Application of Automated Holographic Interferometry," ICIASF 1975 Record, IEEE, New York, New York, p. 237-246, September 1975. 3.64 Bryanston...Presented at the IUTAM Unsteady Aerodynamics Conference, Jesus College, Cambridge, September 1984. 3.70 Bryanston-Cross, P. J., Camus , J. J., and

  13. AIR FLOW AND ENVIRONMENTAL WIND VISUALIZATION USING A CW DIODE PUMPED FREQUENCY DOUBLED Nd:YAG Laser

    Directory of Open Access Journals (Sweden)

    Mircea UDREA

    2009-09-01

    Full Text Available Preliminary results obtained in developing a visualisation technique for non-invasive analysis of air flow inside INCAS subsonic wind tunnel and its appendages are presented. The visualisation technique is based on using a green light sheet generated by a continuous wave (cw longitudinally diode pumped and frequency doubled Nd:YAG laser. The output laser beam is expanded on one direction and collimated on rectangular direction. The system is tailored to the requirements of qualitative analysis and vortex tracking requirements inside the INCAS 2.5m x 2.0m subsonic wind tunnel test section, for measurements performed on aircraft models. Also the developed laser techniques is used for non-invasive air flow field analysis into environmental facilities settling room (air flow calming area. Quantitative analysis is enabled using special image processing tools upon movies and pictures obtained during the experiments. The basic experimental layout in the wind tunnel takes advantage of information obtained from the investigation of various aircraft models using the developed visualisation technique. These results are further developed using a Particle Imaging Velocimetry (PIV experimental technique.The focus is on visualisation techniques to be used for wind flow characterization at different altitudes in indus-trial and civil buildings areas using a light sheet generated by a Nd:YAG cw pumped and doubled laser at 532 nm wave-length. The results are important for prevention of biological/chemical disasters such as spreading of extremely toxic pol-lutants due to wind. Numerical simulations of wind flow and experimental visualisation results are compared. A good agreement between these results is observed.

  14. Application of a structure with a diode thermal effect for solar heating and cooling of a building; Application d'une structure a effet de diode thermique au chauffage et a la climatisation solaire d'un local

    Energy Technology Data Exchange (ETDEWEB)

    Boukadida, N. [Faculte des Sciences de Monastir (Tunisia); Vullierme, J.J. [Ecole Nationale Superieure de Mecanique et d' Aerotechnique (ENSMA), Lab. d' Etudes Thermiques, 86 - Poitiers (France)

    2002-07-01

    The aim of this study is to present the effect of a structure with a diode thermal effect on the building thermal behavior. Numerical simulations allowed us to compare the thermal behavior of a building equipped with this structure on its east, south and west frontages to that of standing or conventional building with large or low inertia. Results showed that the structure has a diode thermal effect mainly for the heating application. The revetment nature of the interior structure sides has an effect on the total coefficient of heat transfer The efficiency of this structure is sensible for cases where we can allow a low temperature inside the building during the winter season for a heating application and a high temperature during the summer season for a cooling application. (authors)

  15. Application of light-emitting diodes (LEDs) in cultivation of phototrophic microalgae: current state and perspectives.

    Science.gov (United States)

    Glemser, M; Heining, M; Schmidt, J; Becker, A; Garbe, D; Buchholz, R; Brück, T

    2016-02-01

    The quality and regulation of the incident light is crucial in microalgae cultivation processes. Depending on wavelength, spectrum, and intensity, growth characteristics and biochemical composition of these organisms vary. With mainly fluorescent lamps (FL) used previously for illumination, such variabilities could not be studied adequately due to their broad emission spectrum. In contrast, light-emitting diodes (LEDs) emit a very narrow wavelength band and enable flexible photobioreactor designs due to their small size. This review provides a condensed overview on the application of LEDs in microalgal cultivation processes. It summarizes the current availability and applicability of LED technologies as an illumination source for research-focused photobioreactor systems. A particular focus is the use of narrow-wavelength LEDs to address fundamental as well as applied aspects of light color on algae biomass and value-added compound formation. In this respect, the application of internal and external illumination systems is reviewed together with trends in the industrial use of LED systems to intensify algae process efficiency.

  16. Application of ultraviolet light-emitting diodes (UV-LEDs) for water disinfection: A review.

    Science.gov (United States)

    Song, Kai; Mohseni, Madjid; Taghipour, Fariborz

    2016-05-01

    Ultraviolet (UV) disinfection is an effective technology for the inactivation of pathogens in water and is of growing interest for industrial application. A new UV source - ultraviolet light-emitting diode (UV-LED) - has emerged in the past decade with a number of advantages compared to traditional UV mercury lamps. This promising alternative raises great interest in the research on application of UV-LEDs for water treatment. Studies on UV-LED water disinfection have increased during the past few years. This article presents a comprehensive review of recent studies on UV-LEDs with various wavelengths for the inactivation of different microorganisms. Many inconsistent and incomparable data were found from published studies, which underscores the importance of establishing a standard protocol for studying UV-LED inactivation of microorganisms. Different UV sensitivities to UV-LEDs and traditional UV lamps were observed in the literature for some microorganisms, which requires further investigation for a better understanding of microorganism response to UV-LEDs. The unique aspects of UV-LEDs improve inactivation effectiveness by applying LED special features, such as multiple wavelengths and pulsed illumination; however, more studies are needed to investigate the influencing factors and mechanisms. The special features of UV-LEDs offer the flexibility of novel reactor designs for a broad application of UV-LED reactors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Bioeffect of lipohemia rabbits irradiated in oral mucosa with 650-nm diode-laser-accompanied oxygen inspiration and clinical application

    Science.gov (United States)

    Yang, Fu-Shou; Tang, Jin-Xian; Liu, Cheng; Yang, Xi-Cheng; Pang, Hi-Xiu

    1998-11-01

    The study on irradiating in oral mucosa of rabbits with 650 nm diode laser and clinical application has been reported in this paper. The result of animal experiment showed: the obvious decrease of cholesterin and triglyceride has been found among those highly lipohemia rabbits in the experiments of 650nm diode laser irradiating accompanying with oxygen, as well as the parameters of hemorheology obviously being improved, as compared with highly lipohemia rabbits un-irradiating, the statistical analysis showing P renal interstitial in the group of rabbits which are irradiated with laser and accompanying with oxygen inspiration, and even the perfectly recovered tissue in some rabbits has been seen. This experimental result is significantly for clinical application. The results of clinic application showed, that the patients employed this method which treatment cerebral infarction, lipohemia, the total effective ratio achieved 91.7 percent, perfect effect 30.6 percent.

  18. Applications, benefits and challenges of flow chemistry

    DEFF Research Database (Denmark)

    Mitic, Aleksandar; Heintz, Søren; Ringborg, Rolf Hoffmeyer

    2013-01-01

    , environmental and manufacturing perspective. A potential solution to resolve these issues is to use flow chemistry in such processes, preferably with applications of micro-and mini-sized equipment. In addition, Process Analytical Technology (PAT) may be implemented in a very efficient way in such equipment due...

  19. Resonant tunnelling diode oscillator as an alternative LO for SIS receiver applications

    Science.gov (United States)

    Blundell, R.; Papa, D. C.; Brown, E. R.; Parker, C. D.

    1993-01-01

    The resonant tunnelling diode (RTD) oscillator has been demonstrated for the first time as a local oscillator (LO) in a heterodyne receiver. Noise measurements made on a sensitive 200 GHz superconductor-insulator-superconductor receiver using both a multiplied Gunn diode and an RTD oscillator as the LO revealed no difference in receiver noise as a function of oscillator type.

  20. New class of compact diode pumped sub 10 fs lasers for biomedical applications

    DEFF Research Database (Denmark)

    Le, T.; Mueller, A.; Sumpf, B.;

    2016-01-01

    Diode-pumping Ti: sapphire lasers promises a new approach to low-cost femtosecond light sources. Thus in recent years much effort has been taken just to overcome the quite low power and low beam qualities of available green diodes to obtain output powers of several hundred milliwatts from a fs-la...

  1. Coaxial foilless diode

    Directory of Open Access Journals (Sweden)

    Long Kong

    2014-05-01

    Full Text Available A kind of coaxial foilless diode is proposed in this paper, with the structure model and operating principle of the diode are given. The current-voltage relation of the coaxial foilless diode and the effects of structure parameters on the relation are studied by simulation. By solving the electron motion equation, the beam deviation characteristic in the presence of external magnetic field in transmission process is analyzed, and the relationship between transverse misalignment with diode parameters is obtained. These results should be of interest to the area of generation and propagation of radial beam for application of generating high power microwaves.

  2. Diode lasers for direct application by utilizing a trepanning optic for remote oscillation welding of aluminum and copper

    Science.gov (United States)

    Fritsche, Haro; Müller, Norbert; Ferrario, Fabio; Fetissow, Sebastian; Grohe, Andreas; Hagen, Thomas; Steger, Ronny; Katzemaikat, Tristan; Ashkenasi, David; Gries, Wolfgang

    2017-02-01

    We report the first direct diode laser module integrated with a trepanning optic for remote oscillation welding. The trepanning optic is assembled with a collimated DirectProcess 900 laser engine. This modular laser is based on single emitters and beam combiners to achieve fiber coupled modules with a beam parameter product or BPP design consists in vertically stacking several diodes in the fast axis which leads to a rectangular output of about 100 W with BPP of product of the original vertical stack without the power loss of fiber coupling. The 500 W building blocks feature a highly flexible emitting wavelength bandwidth. New wavelengths can be configured by simply exchanging parts and without modifying the production process. This design principle provides the option to adapt the wavelength configuration to match a broad set of applications, from the UV to the visible and to the far IR depending on the commercial availability of laser diodes. This opens numerous additional applications like laser pumping, scientific and medical applications, as well as materials processing applications such as cutting and welding of copper aluminum or steel. Furthermore, the module's short lead lengths enable very short pulses. Integrated with electronics, the module's pulse width can be adjusted from micro-seconds to cw mode operation by simple software commands. An optical setup can be directly attached instead of a fiber to the laser module thanks to its modular design. This paper's experimental results are based on a trepanning optic attached to the laser module. Alltogether the setup approximately fits in a shoe box and weighs less than 20 kg which allows for direct mounting onto a 3D-gantry system. The oscillating weld performance of the 500 W direct diode laser utilizing a novel trepanning optic is discussed for its application to aluminum/aluminum and aluminum/copper joints.

  3. Membranes for Redox Flow Battery Applications

    Directory of Open Access Journals (Sweden)

    Maria Skyllas-Kazacos

    2012-06-01

    Full Text Available The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention.

  4. Membranes for redox flow battery applications.

    Science.gov (United States)

    Prifti, Helen; Parasuraman, Aishwarya; Winardi, Suminto; Lim, Tuti Mariana; Skyllas-Kazacos, Maria

    2012-06-19

    The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention.

  5. Diode laser using narrow bandwidth interference filter at 852 nm and its application in Faraday anomalous dispersion optical filter

    Science.gov (United States)

    Jiang, Zhaojie; Zhou, Qi; Tao, Zhiming; Zhang, Xiaogang; Zhang, Shengnan; Zhu, Chuanwen; Lin, Pingwei; Chen, Jingbiao

    2016-08-01

    We demonstrate an 852-nm external cavity diode laser (ECDL) system whose wavelength is mainly determined by an interference filter instead of other wavelength selective elements. The Lorentzian linewidth measured by the heterodyne beating between two identical lasers is 28.3 kHz. Moreover, we test the application of the ECDL in the Faraday atomic filter. Besides saturated absorption spectrum, the transmission spectrum of the Faraday atomic filter at 852 nm is measured by using the ECDL. This interference filter ECDL method can also be extended to other wavelengths and widen the application range of diode laser. Project supported by the National Natural Science Foundation of China (Grant No. 91436210) and the International Science and Technology Cooperation Program of China (Grant No. 2010DFR10900).

  6. Building block diode laser concept for high brightness laser output in the kW range and its applications

    Science.gov (United States)

    Ferrario, Fabio; Fritsche, Haro; Grohe, Andreas; Hagen, Thomas; Kern, Holger; Koch, Ralf; Kruschke, Bastian; Reich, Axel; Sanftleben, Dennis; Steger, Ronny; Wallendorf, Till; Gries, Wolfgang

    2016-03-01

    The modular concept of DirectPhotonics laser systems is a big advantage regarding its manufacturability, serviceability as well as reproducibility. By sticking to identical base components an economic production allows to serve as many applications as possible while keeping the product variations minimal. The modular laser design is based on single emitters and various combining technics. In a first step we accept a reduction of the very high brightness of the single emitters by vertical stacking several diodes in fast axis. This can be theoretically done until the combined fast axis beam quality is on a comparable level as the individual diodes slow axis beam quality without loosing overall beam performance after fiber coupling. Those stacked individual emitters can be wavelength stabilized by an external resonator, providing the very same feedback to each of those laser diodes which leads to an output power of about 100 W with BPP of stacking those building blocks using the very same dense spectral combing technique up to multi kW Systems without further reduction of the BPP. The 500 W building blocks are consequently designed in a way that they feature a high flexibility with regard to their emitting wavelength bandwidth. Therefore, new wavelengths can be implemented by only exchanging parts and without any additional change of the production process. This design principal theoretically offers the option to adapt the wavelength of those blocks to any applications, from UV, visible into the far IR as long as there are any diodes commercially available. This opens numerous additional applications like laser pumping, scientific applications, materials processing such as cutting and welding of copper aluminum or steel and also medical application. Typical operating at wavelengths in the 9XX nm range, these systems are designed for and mainly used in cutting and welding applications, but adapted wavelength ranges such as 793 nm and 1530 nm are also offered. Around 15

  7. Flow cytometry applications in the food industry.

    Science.gov (United States)

    Comas-Riu, Jaume; Rius, Núria

    2009-08-01

    Flow cytometry has become a valuable tool in food microbiology. By analysing large numbers of cells individually using light-scattering and fluorescence measurements, this technique reveals both cellular characteristics and the levels of cellular components. Flow cytometry has been developed to rapidly enumerate microorganisms; to distinguish between viable, metabolically active and dead cells, which is of great importance in food development and food spoilage; and to detect specific pathogenic microorganisms by conjugating antibodies with fluorochromes, which is of great use in the food industry. In addition, high-speed multiparametric data acquisition, analysis and cell sorting, which allow other characteristics of individual cells to be studied, have increased the interest of food microbiologists in this technique. This mini-review gives an overview of the principles of flow cytometry and examples of the application of this technique in the food industry.

  8. Organic semiconductor heterojunction and its application in organic light-emitting diodes (Conference Presentation)

    Science.gov (United States)

    Ma, Dongge

    2016-09-01

    Organic light-emitting diodes (OLEDs) have drawn increasing attention as the next generation displays and lighting sources. High efficiency and long lifetime are necessary for OLEDs in practical applications. In conventional OLEDs, the charge carriers are directly injected into the organic transport layers from electrodes, the injection barriers between the organic transport layers and electrodes are unavoidable due to the mismatch between the work function of metal electrode and the energy level of charge-transport layer, which greatly affects the performance of fabricated OLEDs. Furthermore, tandem OLEDs, which are fabricated by vertically connecting several individual electroluminescent (EL) units together in series via an appropriate charge generation layer (CGL) with the entire device driven by a single power source can significantly enhance current efficiency and stability, but their performance is strongly dependent on the used CGL, especially the power efficiency is difficult to enhance due to the increase of working voltage. Recently we found that organic semiconductor heterojunctions show efficient charge generation effect and as CGL, not only double the luminance and current efficiency, but also greatly improve the power efficiency, which is difficult in tandem OLEDs based on conventional CGLs. We also realized electrode-independent charge injection by using organic semiconductor heterojuncrions as injectors in OLEDs, and obtained comparable electroluminescent (EL) performance with that of conventional OLEDs. Here, we report the results of tandem OLEDs based on organic semiconductor heterojunctions as CGL and OLEDs using organic semiconductor heterojunctions as injectors, and discuss this working mechanism in detail.

  9. Analysis of Noise Failure Characteristics for Superluminescent Diode Fiber-Optic Gyroscopes in Space Applications

    Science.gov (United States)

    Li, Min; Huang, Xiaokai; Jin, Jing; Chen, Yunxia; Kang, Rui

    Noise failure, particularly due to random walk error (RWE) degradation behavior, is one of the critical failure modes for fiber-optic gyroscopes (FOGs) in space applications. In this paper, firstly, the analytical model of RWE is presented and the affected parameters are listed according to the gamma irradiation damage mechanism. In addition, the influence of temperature is also included. The deterioration of affected parameters is determined through a 60Co radiation experiment on optic and optoelectronic components. Based on the parameters’ deterioration range and assumed distribution properties, their importance to the noise failure is calculated through the Sobol method, a global sensitivity analysis method. In the computation steps, the Latin Hyper Sampling (LHS) based Monte-Carlo numerical simulation technique is adopted. It is determined from calculation results that the detected light power (DLP) is the noise failure characteristic which is the most sensitive parameter in the space environment. Finally, another 60Co radiation experiment with the same conditions is performed on a superluminescent diode (SLD) FOG. The original noise degradation behavior is compared to the simulated RWE, calculated according to DLP, and the result shows that they follow trend almost identical. This supports the conclusion that DLP is the most sensitive noise failure characteristic for SLD-based FOGs.

  10. Blue emitting 1,8-naphthalimides with electron transport properties for organic light emitting diode applications

    Science.gov (United States)

    Ulla, Hidayath; Kiran, M. Raveendra; Garudachari, B.; Ahipa, T. N.; Tarafder, Kartick; Adhikari, Airody Vasudeva; Umesh, G.; Satyanarayan, M. N.

    2017-09-01

    In this article, the synthesis, characterization and use of two novel naphthalimides as electron-transporting emitter materials for organic light emitting diode (OLED) applications are reported. The molecules were obtained by substituting electron donating chloro-phenoxy group at the C-4 position. A detailed optical, thermal, electrochemical and related properties were systematically studied. Furthermore, theoretical calculations (DFT) were performed to get a better understanding of the electronic structures. The synthesized molecules were used as electron transporters and emitters in OLEDs with three different device configurations. The devices with the molecules showed blue emission with efficiencies of 1.89 cdA-1, 0.98 lmW-1, 0.71% at 100 cdm-2. The phosphorescent devices with naphthalimides as electron transport materials displayed better performance in comparison to the device without any electron transporting material and were analogous with the device using standard electron transporting material, Alq3. The results demonstrate that the naphthalimides could play a significant part in the progress of OLEDs.

  11. The Development of High-Density Vertical Silicon Nanowires and Their Application in a Heterojunction Diode

    Directory of Open Access Journals (Sweden)

    Wen-Chung Chang

    2016-06-01

    Full Text Available Vertically aligned p-type silicon nanowire (SiNW arrays were fabricated through metal-assisted chemical etching (MACE of Si wafers. An indium tin oxide/indium zinc oxide/silicon nanowire (ITO/IZO/SiNW heterojunction diode was formed by depositing ITO and IZO thin films on the vertically aligned SiNW arrays. The structural and electrical properties of the resulting ITO/IZO/SiNW heterojunction diode were characterized by field emission scanning electron microscopy (FE-SEM, X-ray diffraction (XRD, and current−voltage (I−V measurements. Nonlinear and rectifying I−V properties confirmed that a heterojunction diode was successfully formed in the ITO/IZO/SiNW structure. The diode had a well-defined rectifying behavior, with a rectification ratio of 550.7 at 3 V and a turn-on voltage of 2.53 V under dark conditions.

  12. Mushroom-type structures with the wires connected through diodes: Theory and applications

    Science.gov (United States)

    Forouzmand, Ali; Kaipa, Chandra S. R.; Yakovlev, Alexander B.

    2016-07-01

    In this paper, we establish a general formalism to quantify the interaction of electromagnetic waves with mushroom-type structures (high impedance surface and bi-layer) with diodes inserted along the direction of the wires. The analysis is carried out using the nonlocal homogenization model for the mushroom structure with the generalized additional boundary conditions at the connection of the wires to diodes. We calculate numerically the magnitude and phase of the reflected/transmitted fields in the presence of an ideal and realistic PIN diodes. It is observed that the reflection/transmission characteristics of the mushroom-type structures can be controlled by tuning the working states of the integrated PIN diodes. We realize a structure with a multi-diode switch to minimize the undesired transmission for a particular incident angle. In addition, a dual-band subwavelength imaging lens is designed based on the resonant amplification of evanescent waves, wherein the operating frequency can be tuned by changing the states of the PIN diodes. The analytical results are verified with the full-wave electromagnetic solver CST Microwave Studio, showing a good agreement.

  13. Applications, benefits and challenges of flow chemistry

    DEFF Research Database (Denmark)

    Mitic, Aleksandar; Heintz, Søren; Ringborg, Rolf Hoffmeyer

    2013-01-01

    Organic synthesis (incorporating both chemo-catalysis and biocatalysis) is essential for the production of a wide range of small-molecule pharmaceuticals. However, traditional production processes are mainly based on batch and semi-batch operating modes, which have disadvantages from an economic......, environmental and manufacturing perspective. A potential solution to resolve these issues is to use flow chemistry in such processes, preferably with applications of micro-and mini-sized equipment. In addition, Process Analytical Technology (PAT) may be implemented in a very efficient way in such equipment due...

  14. Multiparameter Flow Cytometry For Clinical Applications

    Science.gov (United States)

    Stewart, Carleton C.

    1989-06-01

    Flow Cytometry facilities are well established and provide immunophenotyping and DNA content measurement services. The application of immunophenotyping has been primarily in monitoring therapy and in providing further information to aid in the definitive diagnosis of immunological and neoplastic disease such as: immunodeficiency disease, auto immune disease, organ transplantation, and leukemia and lymphoma. DNA content measurements have been particularly important in determining the fraction of cycling cells and presence of aneuploid cells in neoplasia. This information has been useful in the management of patients with solid tumors.

  15. Deterministic chaos in RL-diode circuits and its application in metrology

    Science.gov (United States)

    Kucheruk, Volodymyr; Katsyv, Samuil; Glushko, Mykhailo; Wójcik, Waldemar; Zyska, Tomasz; Taissariyeva, Kyrmyzy; Mussabekov, Kanat

    2016-09-01

    The paper investigated the possibility of measuring the resistive physical quantity generator using deterministic chaos based RL-diode circuit. A generalized structure of the measuring device using a deterministic chaos signal generator. To separate the useful component of the measurement signal of amplitude detector is proposed to use. Mathematical modeling of the RL-diode circuit, which showed a significant effect of the barrier and diffusion capacity of the diode on the occurrence of deterministic chaotic oscillations in this circuit. It is shown that this type deterministic chaos signal generator has a high sensitivity to a change in output voltage resistance in the range of 250 Ohms, which can be used to create the measuring devices based on it.

  16. Next generation 9xx/10xx nm high power laser diode bars for multi-kilowatt industrial applications

    Science.gov (United States)

    Commin, Paul; Todt, René; Krejci, Martin; Bättig, Rainer; Brunner, Reinhard; Lichtenstein, Norbert

    2013-02-01

    We report on the development of high power, 9xx-10xx nm laser diode bars for use in direct diode systems and for solidstate and fibre laser pumping with applications in industrial markets. For 1 cm wide bars on micro channel cooler (MCC) we have achieved a reliable output power of 250 W across the 900 nm - 1060 nm range. At this output power level we have achieved power conversion efficiencies of 65-66 % and 90 % power content slow axis beam divergence of ~6.5°. Results of a 6400 h life test show an average power degradation of 0.6 % per 1000 h at this operating power level. We will also show results of high power bars assembled on the new OCLARO conductive cooler, the BLM. This new cooler has a small footprint of 12.6 mm × 24.8 mm and is designed for lateral or vertical stacking of diodes in multi kilowatt systems but with the benefits associated with a conductive cooler. The thermal properties are shown to be the same as for a standard CS mount. 1 cm wide high fill factor bars and 0.5 cm wide low fill factor half bars assembled on the BLM operate at 63-64 % power conversion efficiency (PCE) with output powers of up to 250 W and 150 W, respectively.

  17. Silicon Carbide Schottky Barrier Diode

    Science.gov (United States)

    Zhao, Jian H.; Sheng, Kuang; Lebron-Velilla, Ramon C.

    2004-01-01

    This chapter reviews the status of SiC Schottky barrier diode development. The fundamental of Schottky barrier diodes is first provided, followed by the review of high-voltage SiC Schottky barrier diodes, junction-barrier Schottky diodes, and merged-pin-Schottky diodes. The development history is reviewed ad the key performance parameters are discussed. Applications of SiC SBDs in power electronic circuits as well as other areas such as gas sensors, microwave and UV detections are also presented, followed by discussion of remaining challenges.

  18. Optical, electrical, and magnetic field studies of organic materials for light emitting diodes and photovoltaic applications

    Science.gov (United States)

    Basel, Tek Prasad

    We studied optical, electrical, and magnetic field responses of films and devices based on organic semiconductors that are used for organic light emitting diodes (OLEDs) and photovoltaic (OPV) solar cell applications. Our studies show that the hyperfine interaction (HFI)-mediated spin mixing is the key process underlying various magnetic field effects (MFE) and spin transport in aluminum tris(8-hydroxyquinoline)[Alq3]-based OLEDs and organic spin-valve (OSV). Conductivity-detected magnetic resonance in OLEDs and magneto-resistance (MR) in OSVs show substantial isotope dependence. In contrast, isotope-insensitive behavior in the magneto-conductance (MC) of same devices is explained by the collision of spin ½ carriers with triplet polaron pairs. We used steady state optical spectroscopy for studying the energy transfer dynamics in films and OLEDs based on host-guest blends of the fluorescent polymer and phosphorescent molecule. We have also studied the magnetic-field controlled color manipulation in these devices, which provide a strong proof for the `polaron-pair' mechanism underlying the MFE in organic devices. The critical issue that hampers organic spintronics device applications is significant magneto-electroluminescence (MEL) at room temperature (RT). Whereas inorganic spin valves (ISVs) show RT magneto-resistance, MR>80%, however, the devices do not exhibit electroluminescence (EL). In contrast, OLEDs show substantive EL emission, and are particularly attractive because of their flexibility, low cost, and potential for multicolor display. We report a conceptual novel hybrid organic/inorganic spintronics device (h-OLED), where we employ both ISV with large MR at RT, and OLED that has efficient EL emission. We investigated the charge transfer process in an OPV solar cell through optical, electrical, and magnetic field measurements of thin films and devices based on a low bandgap polymer, PTB7 (fluorinated poly-thienothiophene-benzodithiophene). We found that

  19. Application of flow cytometry to wine microorganisms.

    Science.gov (United States)

    Longin, Cédric; Petitgonnet, Clément; Guilloux-Benatier, Michèle; Rousseaux, Sandrine; Alexandre, Hervé

    2017-04-01

    Flow cytometry (FCM) is a powerful technique allowing detection and enumeration of microbial populations in food and during food process. Thanks to the fluorescent dyes used and specific probes, FCM provides information about cell physiological state and allows enumeration of a microorganism in a mixed culture. Thus, this technique is increasingly used to quantify pathogen, spoilage microorganisms and microorganisms of interest. Since one decade, FCM applications to the wine field increase greatly to determine population and physiological state of microorganisms performing alcoholic and malolactic fermentations. Wine spoilage microorganisms were also studied. In this review we briefly describe FCM principles. Next, a deep revision concerning enumeration of wine microorganisms by FCM is presented including the fluorescent dyes used and techniques allowing a yeast and bacteria species specific enumeration. Then, the last chapter is dedicated to fluorescent dyes which are used to date in fluorescent microscopy but applicable in FCM. This chapter also describes other interesting "future" techniques which could be applied to study the wine microorganisms. Thus, this review seeks to highlight the main advantages of the flow cytometry applied to wine microbiology.

  20. Electronic properties of Al/DNA/p-Si MIS diode: Application as temperature sensor

    Energy Technology Data Exchange (ETDEWEB)

    Guellue, O., E-mail: omergullu@gmail.com [Batman University, Science and Art Faculty, Department of Physics, 72060 Batman (Turkey); Osmaniye Korkut Ata University, Science and Art Faculty, Department of Physics, 80000 Osmaniye (Turkey); Tueruet, A. [Atatuerk University, Science Faculty, Department of Physics, 25240 Erzurum (Turkey)

    2011-01-21

    Research highlights: > This work proposes that DNA molecules should be considered, among other candidates, as a potential organic thin film for metal-interface layer-semiconductor devices. > We successfully fabricated Al/DNA/p-Si device with interlayer by a simple cast method. > The temperature is found to significantly effect the electrical properties of the Al/DNA/p-Si device. > The facts: (i) that the technology of the fabrication of a Al/DNA/p-Si Schottky diode much simpler and economical than that for the Si p-n junction and (ii) the sensibility of the Al/DNA/p-Si Schottky diode as temperature sensor is 42% higher than that of a Si p-n junction, indicate that the Al/DNA/p-Si Schottky diode is a good alternative as temperature sensor. - Abstract: The current-voltage (I-V) measurements were performed in the temperature range (200-300 K) on Al/DNA/p-Si Schottky barrier type diodes. The Schottky diode shows non-ideal I-V behaviour with ideality factors n equal to 1.34 {+-} 0.02 and 1.70 {+-} 0.02 at 300 K and 200 K, respectively, and is thought to have a metal-interface layer-semiconductor (MIS) configuration. The zero-bias barrier height {Phi}{sub b} determined from the I-V measurements was 0.75 {+-} 0.01 eV at 300 K and decreases to 0.61 {+-} 0.01 eV at 200 K. The forward voltage-temperature (V{sub F}-T) characteristics were obtained from the I-V measurements in the temperature range 200-300 K at different activation currents (I{sub F}) in the range 20 nA-6 {mu}A. The V{sub F}-T characteristics were linear for three activation currents in the diode. From the V{sub F}-T characteristics at 20 nA, 100 nA and 6 {mu}A, the values of the temperature coefficients of the forward bias voltage (dV{sub F}/dT) for the diode were determined as -2.30 mV K{sup -1}, -2.60 mV K{sup -1} and -3.26 mV K{sup -1} with a standard error of 0.05 mV K{sup -1}, respectively.

  1. Investigation of tunable diode laser absorption spectroscopy for its application as primary standard for partial pressure measurements

    Energy Technology Data Exchange (ETDEWEB)

    Jousten, K; Bock, T [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, D-10587 Berlin (Germany); Padilla-VIquez, G [Laboratorio Costarricense de MetrologIa (Lacomet), Ciudad de la Investigacion de la UCR, San Pedro de Montes de Oca (Costa Rica)], E-mail: Karl.jousten@ptb.de

    2008-03-01

    Partial pressures in vacuum systems can be quite accurately measured by tunable diode laser absorption spectroscopy in the infrared. To examine the possibility for its application as primary standard, for CO{sub 2} in the 2-{mu}m-region we made full traceability to the respective SI unit for each input quantity of the model, evaluated the results according to the ISO guide to the expression of uncertainty in measurement, and validated the method successfully by comparison with gravimetrically produced samples of CO{sub 2} in N{sub 2}.

  2. Low noise InGaAs/InP single-photon negative feedback avalanche diodes: characterization and applications

    Science.gov (United States)

    Boso, Gianluca; Korzh, Boris; Lunghi, Tommaso; Zbinden, Hugo

    2015-05-01

    In recent years, many applications have been proposed that require detection of light signals in the near-infrared range with single-photon sensitivity and time resolution down to few hundreds of picoseconds. InGaAs/InP singlephoton avalanche diodes (SPADs) are a viable choice for these tasks thanks to their compactness and ease-of-use. Unfortunately, their performance is traditionally limited by high dark count rates (DCRs) and afterpulsing effects. However, a recent demonstration of negative feedback avalanche diodes (NFADs), operating in the free-running regime, achieved a DCR down to 1 cps at 10 % photon detection efficiency (PDE) at telecom wavelengths. Here we present our recent results on the characterization of NFAD detectors for temperatures down to approximately 150 K. A FPGA controlled test-bench facilitates the acquisition of all the parameters of interest like PDE, DCR, afterpulsing probability etc. We also demonstrate the performance of the detector in different applications: In particular, with low-temperature NFADs, we achieved high secret key rates with quantum key distribution over fiber links between 100-300 km. But low noise InGaAs/InP SPADs will certainly find applications in yet unexplored fields like photodynamic therapy, near infrared diffuse optical spectroscopy and many more. For example with a large area detector, we made time-resolved measurements of singlet-oxygen luminescence from a standard Rose Bengal dye in aqueous solution.

  3. Applications of Imaging Flow Cytometry for Microalgae.

    Science.gov (United States)

    Hildebrand, Mark; Davis, Aubrey; Abbriano, Raffaela; Pugsley, Haley R; Traller, Jesse C; Smith, Sarah R; Shrestha, Roshan P; Cook, Orna; Sánchez-Alvarez, Eva L; Manandhar-Shrestha, Kalpana; Alderete, Benjamin

    2016-01-01

    The ability to image large numbers of cells at high resolution enhances flow cytometric analysis of cells and cell populations. In particular, the ability to image intracellular features adds a unique aspect to analyses, and can enable correlation between molecular phenomena resulting in alterations in cellular phenotype. Unicellular microalgae are amenable to high-throughput analysis to capture the diversity of cell types in natural samples, or diverse cellular responses in clonal populations, especially using imaging cytometry. Using examples from our laboratory, we review applications of imaging cytometry, specifically using an Amnis(®) ImageStream(®)X instrument, to characterize photosynthetic microalgae. Some of these examples highlight advantages of imaging flow cytometry for certain research objectives, but we also include examples that would not necessarily require imaging and could be performed on a conventional cytometer to demonstrate other concepts in cytometric evaluation of microalgae. We demonstrate the value of these approaches for (1) analysis of populations, (2) documentation of cellular features, and (3) analysis of gene expression.

  4. Current transport across the pentacene/CVD-grown graphene interface for diode applications.

    Science.gov (United States)

    Berke, K; Tongay, S; McCarthy, M A; Rinzler, A G; Appleton, B R; Hebard, A F

    2012-06-27

    We investigate the electronic transport properties across the pentacene/graphene interface. Current transport across the pentacene/graphene interface is found to be strikingly different from transport across pentacene/HOPG and pentacene/Cu interfaces. At low voltages, diodes using graphene as a bottom electrode display Poole–Frenkel emission, while diodes with HOPG and Cu electrodes are dominated by thermionic emission. At high voltages conduction is dominated by Poole–Frenkel emission for all three junctions. We propose that current across these interfaces can be accurately modeled by a combination of thermionic and Poole–Frenkel emission. Results presented not only suggest that graphene provides low resistive contacts to pentacene where a flat-laying orientation of pentacene and transparent metal electrodes are desired but also provides further understanding of the physics at the organic semiconductor/graphene interface.

  5. Properties of CoPt ferromagnetic layers for application in spin light-emitting diodes

    Science.gov (United States)

    Zdoroveyshchev, A. V.; Dorokhin, M. V.; Vikhrova, O. V.; Demina, P. B.; Kudrin, A. V.; Temiryazev, A. G.; Temiryazeva, M. P.

    2016-11-01

    The magnetic properties of Co45Pt55 films deposited by electron-beam evaporation in vacuum have been studied. The measurements of the Faraday and Kerr magnetooptical effects confirm the presence of the easy-magnetization axis perpendicular to the Co45Pt55 surface. It is shown that the perpendicular magnetic anisotropy and the residual magnetization are retained at 300 K for a long time. The magnetic characteristics of the Co45Pt55 layer surface have been studied by magnetic force microscopy, and "circular" mobile magnetic structures have been detected. The spin light-emitting diodes based on In(Ga)As/GaAs heteronanostructures with Co45Pt55 contact layers were fabricated. These diodes emit circularly-polarized light in the absence of an external magnetic field.

  6. High-quality distributed Bragg reflectors for resonant-cavity light-emitting diode applications

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, S.; Naranjo, F.B.; Calle, F.; Sanchez-Garcia, M.A.; Calleja, E. [ISOM, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Departamento de Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Vennegues, P. [CHREA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France)

    2002-08-16

    Efficient distributed Bragg reflectors based on Al{sub x}Ga{sub 1} {sub -} {sub x}N/GaN multilayer stacks have been grown by plasma-assisted molecular-beam epitaxy on GaN/Al{sub 2}O{sub 3} templates. The final goal is to incorporate these reflectors as bottom mirrors in a backside (sapphire) resonant-cavity light-emitting diode at 510 nm. The reflectors have been characterised by atomic force microscopy, high-resolution X-ray diffraction and high-resolution transmission electron microscopy. Reflectivity measurements have also been performed, obtaining values between 30% and 50%, depending on the Al content used. The incorporation of the Al{sub x}Ga{sub 1} {sub -} {sub x}N/GaN Bragg reflector as bottom mirror in a RCLED structure improves the output power by a factor of 12 compared with conventional light-emitting diodes. (Abstract Copyright[2002], Wiley Periodicals, Inc.)

  7. Optical and structural properties of CuO nanofilm: Its diode application

    Energy Technology Data Exchange (ETDEWEB)

    Erdogan, Ibrahim Y. [Bingoel University, Faculty of Sciences and Arts, Department of Chemistry, 12000 Bingoel (Turkey); Guellue, O., E-mail: omergullu@gmail.co [Batman University, Faculty of Sciences and Arts, Department of Physics, 72060 Batman (Turkey)

    2010-03-04

    The high crystalline CuO nanofilms have been prepared by spin coating and annealing combined with a simple chemical method. The obtained films have been characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-vis (UV-vis) spectroscopy and photoluminescence (PL) spectroscopy. Structural analysis results demonstrate that the single phase CuO on Si (1 0 0) substrate is of high a crystalline structure with a dominant in monoclinic (1 1 1) orientation. FT-IR results confirm the formation of pure CuO phase. UV-vis absorption measurements indicate that the band gap of the CuO films is 2.64 eV. The PL spectrum of the CuO films shows a broad emission band centered at 467 nm, which is consistent with absorption measurement. Also, Au/CuO/p-Si metal/interlayer/semiconductor (MIS) diodes have been fabricated. Electronic properties (current-voltage) of these structures were investigated. In addition, the interfacial state properties of the MIS diode were obtained. The interface-state density of the MIS diode was found to vary from 6.21 x 10{sup 12} to 1.62 x 10{sup 12} eV{sup -1} cm{sup -2}.

  8. Narrow-line, tunable, high-power diode laser pump for DPAL applications

    Science.gov (United States)

    Pandey, Rajiv; Merchen, David; Stapleton, Dean; Irwin, David; Humble, Chuck; Patterson, Steve; Kissel, Heiko; Biesenbach, Jens

    2013-05-01

    We report on a high-power diode laser pump source for diode-pumped alkali lasers (DPAL), specifically rubidium alkali vapor lasers at 780nm, delivering up to 100W/bar with FWHM spectral line width of 0.06nm (~30GHz). This pump is based on a micro-channel water-cooled stack with collimation in both-axes. Wavelength-locking of the output spectrum allows absorption in one of the very narrow resonance lines of the atomic rubidium alkali vapor. To achieve these results, research was conducted to deliver the highest performance on all key components of the product from the diode laser bar which produces the optical power at 780nm to the external Bragg gratings which narrow the spectrum line width. We highlight the advancements in the epitaxy, device design, beam collimation, grating selection, alignment, tunability and thermal control that enable realization of this novel pump-source for DPALs. Design trade-offs will be presented.

  9. Evaluation of 1024 channel VUV-photo-diodes for soft x-ray diagnostic applications

    Energy Technology Data Exchange (ETDEWEB)

    Molvik, A.W.

    1997-04-25

    We tested the operation of 1024 channel diode arrays (Model AXUV-1024, from IRD, Inc.) in subdued room light to establish that they worked and to determine the direction and speed of the scan of the 1024 channels. Further tests were performed in vacuum in the HAP, High-Average-Power Facility. There we found that the bare or glass covered diodes detected primarily visible light as expected, but diodes filtered by aluminized parylene, produced a signal consistent with soft x-rays. It is probable that the spectral response and sensitivity, as discussed below, reproduce that previously demonstrated by 1 to 16 channel VUV-photodiodes; however, significantly more effort would be required to establish that experimentally. These detectors appear to be worth further evaluation where 25 w spatial resolution bolometers or spectrograph detectors of known sensitivity are required, and single-shot or 0.02-0.2s time response is adequate. (Presumably, faster readout would be available with custom drive circuitry.)

  10. Design and manufacture of planar GaAs Gunn diode for millimeter wave application

    Science.gov (United States)

    Huang, Jie; Yang, Hao; Tian, Chao; Dong, Jun-Rong; Zhang, Hai-Ying; Guo, Tian-Yi

    2010-12-01

    GaAs-based planar Gunn diodes with AlGaAs hot electron injector have been successfully developed to be used as a local oscillator of 76 GHz in monolithic millimeter-wave integrated circuits. We designed two kinds of structure diode, one has a fixed distance between the anode and cathode, but has variational cathode area, the other has a fixed cathode area, but has different distances between two electrodes. The fabrication of Gunn diode is performed in accordance with the order of operations: cathode defining, mesa etching, anode defining, isolation, passivation, via hole and electroplating. A peak current density of 29.5 kA/cm2 is obtained. And the characteristics of negative differential resistance and the asymmetry of the current—voltage curve due to the AlGaAs hot electron injector are discussed in detail. It is demonstrated that the smaller size of active area corresponds to the smaller current, and the shorter distance between anode and cathode also corresponds to the lower threshold voltage and higher peak current, and hot electron injector can effectively enhance the radio frequency conversion efficiency and output power.

  11. The applications of diode and Er:YAG lasers in labial frenectomy in infant patients.

    Science.gov (United States)

    Gontijo, Isa; Navarro, Ricardo S; Haypek, Patrícia; Ciamponi, Ana Lídia; Haddad, Ana Estela

    2005-01-01

    This paper describes a clinical case of labial frenectomy using different high power lasers: diode (810 nm) and Er:YAG (2940 nm). Considerations are made about specific indications, surgery techniques, and advantages of labial frenectomy using these laser wavelengths. The diode laser has high absorbance by pigmented tissues with hemoglobin, melanin, and collagen chromophores. For this reason, this wavelength is well indicated for surgery in soft tissue (vaporization, incision, coagulation, hemostasis). It is not properly absorbed, however, and should never be used in contact with hard tissues (bone). The Er:YAG laser has high absorbance to water and mineral apatite, making this wavelength useful and safe for the ablation of hard tissues. In the labial frenectomy clinical procedure, a combined technique is suggested: using the diode laser in soft tissues and the Er:YAG laser in periosteal bone tissues and for removal of final collagen fibers. It is important for the professional to understand the physical characteristics of the different laser wavelengths and their interaction with biological tissues to assure that they are used in a safe way, and that the benefits of this technology can be provided to infant patients.

  12. Fabrication, characterization and applications of flexible vertical InGaN micro-light emitting diode arrays.

    Science.gov (United States)

    Tian, Pengfei; McKendry, Jonathan J D; Gu, Erdan; Chen, Zhizhong; Sun, Yongjian; Zhang, Guoyi; Dawson, Martin D; Liu, Ran

    2016-01-11

    Flexible vertical InGaN micro-light emitting diode (micro-LED) arrays have been fabricated and characterized for potential applications in flexible micro-displays and visible light communication. The LED epitaxial layers were transferred from initial sapphire substrates to flexible AuSn substrates by metal bonding and laser lift off techniques. The current versus voltage characteristics of flexible micro-LEDs degraded after bending the devices, but the electroluminescence spectra show little shift even under a very small bending radius 3 mm. The high thermal conductivity of flexible metal substrates enables high thermal saturation current density and high light output power of the flexible micro-LEDs, benefiting the potential applications in flexible high-brightness micro-displays and high-speed visible light communication. We have achieved ~40 MHz modulation bandwidth and 120 Mbit/s data transmission speed for a typical flexible micro-LED.

  13. Diode, transistor & fet circuits manual

    CERN Document Server

    Marston, R M

    2013-01-01

    Diode, Transistor and FET Circuits Manual is a handbook of circuits based on discrete semiconductor components such as diodes, transistors, and FETS. The book also includes diagrams and practical circuits. The book describes basic and special diode characteristics, heat wave-rectifier circuits, transformers, filter capacitors, and rectifier ratings. The text also presents practical applications of associated devices, for example, zeners, varicaps, photodiodes, or LEDs, as well as it describes bipolar transistor characteristics. The transistor can be used in three basic amplifier configuration

  14. Schottky Diode Applications of the Fast Green FCF Organic Material and the Analyze of Solar Cell Characteristics

    Science.gov (United States)

    Çaldiran, Z.; Aydoğan, Ş.; İncekara, Ü.

    2016-05-01

    In this study, a device applications of organic material Fast Green FCF (C37H34N2Na2O10S3Na2) has been investigated. After chemical cleaning process of boron doped H-Si crystals, Al metal was coated on the one surface of crystals by thermal evaporation and fast green organic materials were coated on other surface of crystals with spin coating method (coating parameters; 800 rpm for 60 s). Finally, Ni metal was coated on Fast Green by sputtering and we obtained the Ni/Fast Green FCF/n-Si/Al Schottky type diode. And then we calculated the basic diode parameters of device with current-voltage (I-V) and capacitance- voltage (C-V) measurements at the room temperature. We calculated the ideality factory (n), barrier height (Φb) of rectifing contact from I-V measurements using thermionic emission methods. Furthermore, we calculated ideality factory (n), barrier height (Φb) and series resistance (Rs) of device using Cheung and Norde functions too. The diffusion potential, barrier height, Fermi energy level and donor concentration have been determined from the linear 1/C2-V curves at reverse bias, at room temperature and various frequencies. Besides we measured the current-voltage (I-V) at under light and analyzed the characteristics of the solar cell device.

  15. Electrical transport characterization of PEDOT:PSS/n-Si Schottky diodes and their applications in solar cells.

    Science.gov (United States)

    Khurelbaatar, Zagarzusem; Hyung, Jung-Hwan; Kim, Gil-Sung; Park, No-Won; Shim, Kyu-Hwan; Lee, Sang-Kwon

    2014-06-01

    We demonstrate locally contacted PEDOT:PSS Schottky diodes with excellent rectifying behavior, fabricated on n-type Si substrates using a spin-coating process and a reactive-ion etching process. Electrical transport characterizations of these Schottky diodes were investigated by both current-voltage (I-V) and capacitance-voltage (C-V) measurements. We found that these devices exhibit excellent modulation in the current with an on/off ratio of - 10(6). Schottky junction solar cells composed of PEDOT:PSS and n-Si structures were also examined. From the current density-voltage (J-V) measurement of a solar cell under illumination, the short circuit current (I(sc)), open circuit voltage (V(oc)), and conversion efficiency (eta) were - 19.7 mA/cm2, - 578.5 mV, and - 6.5%, respectively. The simple and low-cost fabrication process of the PEDOT:PSS/n-Si Schottky junctions makes them a promising candidate for further high performance solar cell applications.

  16. All-diode-laser cooling of Sr+ isotope ions for analytical applications

    Science.gov (United States)

    Jung, Kyunghun; Yamamoto, Kazuhiro; Yamamoto, Yuta; Miyabe, Masabumi; Wakaida, Ikuo; Hasegawa, Shuichi

    2017-06-01

    Trapping and cooling of Sr+ isotope ions by an all-diode-laser system has been demonstrated in order to develop a novel mass spectrometric technique in combination with ion trap-laser cooling. First, we constructed external cavity diode lasers and associated stabilization apparatus for laser cooling of Sr+ ions. The transition frequencies confirmed by optogalvanic spectroscopy enabled successful cooling of 88Sr+ ions. An image of two trapped ions has been captured by CCD camera. Minor isotopes, 84Sr+ and 86Sr+, were also cooled and trapped. From an analysis of the observed spectra of a string crystal of each isotope, the isotope shifts of the cooling transition (5s 2S1/2 → 5p 2P1/2) of Sr+ ions were determined to be +371(8) MHz for Δν84-88 and +169(8) MHz for Δν86-88. In the case of the repumping transition (4d 2D3/2 → 5p 2P1/2), Δν84-88 and Δν86-88 were measured to be -833(6) and -400(5) MHz, respectively. These values are in good agreement with previously reported values.

  17. Light-emitting Diodes

    Science.gov (United States)

    Opel, Daniel R.; Hagstrom, Erika; Pace, Aaron K.; Sisto, Krisanne; Hirano-Ali, Stefanie A.; Desai, Shraddha

    2015-01-01

    Background: In the early 1990s, the biological significance of light-emitting diodes was realized. Since this discovery, various light sources have been investigated for their cutaneous effects. Study design: A Medline search was performed on light-emitting diode lights and their therapeutic effects between 1996 and 2010. Additionally, an open-label, investigator-blinded study was performed using a yellow light-emitting diode device to treat acne, rosacea, photoaging, alopecia areata, and androgenetic alopecia. Results: The authors identified several case-based reports, small case series, and a few randomized controlled trials evaluating the use of four different wavelengths of light-emitting diodes. These devices were classified as red, blue, yellow, or infrared, and covered a wide range of clinical applications. The 21 patients the authors treated had mixed results regarding patient satisfaction and pre- and post-treatment evaluation of improvement in clinical appearance. Conclusion: Review of the literature revealed that differing wavelengths of light-emitting diode devices have many beneficial effects, including wound healing, acne treatment, sunburn prevention, phototherapy for facial rhytides, and skin rejuvenation. The authors’ clinical experience with a specific yellow light-emitting diode device was mixed, depending on the condition being treated, and was likely influenced by the device parameters. PMID:26155326

  18. Application of photogrammetry to surface flow visualization

    Energy Technology Data Exchange (ETDEWEB)

    Karthikeyan, N.; Venkatakrishnan, L. [Council of Scientific and Industrial Research, Experimental Aerodynamics Division, National Aerospace Laboratories, Delhi (India)

    2011-03-15

    The construction of three-dimensional surface flow fields is an extremely difficult task owing largely to the fragmented information available in the form of 2D images. Here, the method of photogrammetric resection based on a comprehensive camera model has been used to map oil flow visualization images on to the surface grid of the model. The data exported in the VRML format allow for user interaction in a manner not possible with 2D images. The technique is demonstrated here using the surface oil flow visualization images of a simplified landing gear model at low speed in a conventional wind tunnel without any specialized rigs for photogrammetry. The results are not limited to low-speed regimes and show that this technique can have significant impact on understanding the flow physics associated with the surface flow topology of highly three-dimensional separated flows on complex models. (orig.)

  19. Measurement of the parameters of non-stationary gas flows by diode laser absorption spectroscopy in case of high temperature and high pressure

    Science.gov (United States)

    Bolshov, M. A.; Liger, V. V.; Kuritsyn, Yu. A.; Mironenko, V. R.; Ponurovskii, Ya. Ya.; Kolesnikov, O. M.

    2016-12-01

    Experimental version of diode laser absorption spectrometer (DLAS) for contactless measurements of temperature and water vapor concentration in supersonic gas flows is developed. The spectrometer can be used for the measurements of temperature up to 2500 K and total pressure up to 3 atm. The technique is based on the registration of the transient absorption spectra of a target molecules and fitting of the experimental spectra by the simulated ones constructed using the spectroscopic databases. The temperature is inferred from the ratio of the intensities of the absorption lines with different low energy levels. In gas media with the above parameters the absorption lines are broadened which demands the use of two diode lasers (DL) working in different spectral ranges. The software for selection of the optimal line combinations was developed. The combination of two strong lines in the spectral ranges 1.39 μ and 1.34 μ was selected as the optimal one. The efficiency of the developed technique was exemplified in the first set of the experiments in conditions of real propulsion in Zhukovsky Central Aerohydrodynamic Institute (TsAGI) for the temperatures within (500-2200) K range and total pressure up to 3 atm.

  20. Flow Control for Supersonic Inlet Applications

    Science.gov (United States)

    2014-06-10

    1221-1233, May 2013 3. Loth, E., Titchener, N., Babinsky, H., Povinelli , L., “Canonical NSBLI Flows Relevant to External Compression Inlets”, AIAA J...Tennessee, Jan. 9-12, 2012 7. Loth, E.L., Titchener, N., Babinsky, H., Povinelli , L.A., “A Canonical Normal SBLI Flow Relevant to External

  1. A Comparative Analysis of Thermal Flow Sensing in Biomedical Applications

    CERN Document Server

    Khan, Baseerat; Kakkar, Vipan

    2016-01-01

    Flow sensors have diverse applications in the field of biomedical engineering and also in industries. Micromachining of flow sensors has accomplished a new goal when it comes to miniaturization. Due to the scaling in dimensions, power consumption, mass cost, sensitivity and integration with other modules such as wireless telemetry has improvised to a great extent. Thermal flow sensors find wide applications in biomedical such as in hydrocephalus shunts and drug delivery systems. Infrared thermal sensing is used for preclinical diagnosis of breast cancer, for identifying various neurological disorders and for monitoring various muscular movements. In this paper, various modes of thermal flow sensing and transduction methods with respect to different biomedical applications are discussed. Thermal flow sensing is given prime focus because of the simplicity in the design. Finally, a comparison of flow sensing technologies is also presented.

  2. Scaling of nano-Schottky-diodes

    NARCIS (Netherlands)

    Smit, G.D.J.; Rogge, S.; Klapwijk, T.M.

    2002-01-01

    A generally applicable model is presented to describe the potential barrier shape in ultrasmall Schottky diodes. It is shown that for diodes smaller than a characteristic length lc (associated with the semiconductor doping level) the conventional description no longer holds. For such small diodes th

  3. Novel Strategy for Photopatterning Emissive Polymer Brushes for Organic Light Emitting Diode Applications

    Science.gov (United States)

    2017-01-01

    A light-mediated methodology to grow patterned, emissive polymer brushes with micron feature resolution is reported and applied to organic light emitting diode (OLED) displays. Light is used for both initiator functionalization of indium tin oxide and subsequent atom transfer radical polymerization of methacrylate-based fluorescent and phosphorescent iridium monomers. The iridium centers play key roles in photocatalyzing and mediating polymer growth while also emitting light in the final OLED structure. The scope of the presented procedure enables the synthesis of a library of polymers with emissive colors spanning the visible spectrum where the dopant incorporation, position of brush growth, and brush thickness are readily controlled. The chain-ends of the polymer brushes remain intact, affording subsequent chain extension and formation of well-defined diblock architectures. This high level of structure and function control allows for the facile preparation of random ternary copolymers and red–green–blue arrays to yield white emission. PMID:28691078

  4. Parametric System Identification of Thermoelectric Cooler for Single Photon Avalanche Diode Application

    Directory of Open Access Journals (Sweden)

    Nurul Izzati Samsuddin

    2013-06-01

    Full Text Available The purpose of this study is to model the Thermoelectric Coolers (TEC by means of computational intelligence system identification. Thermoelectric coolers are widely used in cooling, maintaining and stabilizing the temperature of the Single Photon Avalanche Diode (SPAD. SPAD is a temperature sensitive optoelectronic device, where even a slight variation in temperature can cause unstable performance in quantum efficiency, responsibility and dark counts. However, it is not a simple task to derive a mathematical model for TEC since it varies with the operating condition. In this study, Particle Swarm Optimization (PSO was used to identify the mathematical model of the multistage TEC (1639733 from Element 14, which encapsulates dynamics of the SPAD, heat sink and components of the cooling heat exchanger. The model was validated by correlation tests, percentage accuracy and also by comparing its time and frequency responses against that of the TEC. It was found that the obtained model has a good representation of the actual system.

  5. Discrete mode laser diodes for FTTH/PON applications up to 10 Gbit/s

    Science.gov (United States)

    O'Carroll, John; Phelan, Richard; Kelly, Brian; Byrne, Diarmuid; Latkowski, Sylwester; Anandarajah, Prince M.; Barry, Liam P.

    2012-06-01

    Discrete Mode Laser Diodes (DMLDs) present an economic approach with a focus on high volume manufacturability of single mode lasers using a single step fabrication process. We report on a DMLD designed for operation in the 1550 nm window with high Side Mode Suppression Ratio (SMSR) over a wide temperature tuning range of -20 °C < T < 95 °C. Direct modulation rates as high as 10 Gbit/s are demonstrated at both 1550 nm and 1310 nm. Transmission experiments were also carried out over single mode fibre at both wavelengths. Using dispersion pre-compensation transmission from 0 to 60 km is demonstrated at 1550 nm with a maximum power penalty measured at 60 km of 3.6 dB.

  6. Soluble Flavanthrone Derivatives: Synthesis, Characterization, and Application to Organic Light-Emitting Diodes.

    Science.gov (United States)

    Kotwica, Kamil; Bujak, Piotr; Data, Przemyslaw; Krzywiec, Wojciech; Wamil, Damian; Gunka, Piotr A; Skorka, Lukasz; Jaroch, Tomasz; Nowakowski, Robert; Pron, Adam; Monkman, Andrew

    2016-06-01

    Simple modification of benzo[h]benz[5,6]acridino[2,1,9,8-klmna]acridine-8,16-dione, an old and almost-forgotten vat dye, by reduction of its carbonyl groups and subsequent O-alkylation, yields solution-processable, electroactive, conjugated compounds of the periazaacene type, suitable for the use in organic electronics. Their electrochemically determined ionization potential and electron affinity of about 5.2 and -3.2 eV, respectively, are essentially independent of the length of the alkoxyl substituent and in good agreement with DFT calculations. The crystal structure of 8,16-dioctyloxybenzo[h]benz[5,6]acridino[2,1,9,8-klmna]acridine (FC-8), the most promising compound, was solved. It crystallizes in space group P1‾ and forms π-stacked columns held together in the 3D structure by dispersion forces, mainly between interdigitated alkyl chains. Molecules of FC-8 have a strong tendency to self-organize in monolayers deposited on a highly oriented pyrolytic graphite surface, as observed by STM. 8,16-Dialkoxybenzo[h]benz[5,6]acridino[2,1,9,8-klmna]acridines are highly luminescent, and all have photoluminescence quantum yields of about 80 %. They show efficient electroluminescence, and can be used as guest molecules with a 4,4'-bis(N-carbazolyl)-1,1'-biphenyl host in guest/host-type organic light-emitting diodes. The best fabricated diodes showed a luminance of about 1900 cd m(-12) , a luminance efficiency of about 3 cd A(-1) , and external quantum efficiencies exceeding 0.9 %.

  7. Photodynamic therapy of murine non-melanoma skin carcinomas with diode laser after topical application of aluminum phthalocyanine chloride

    Science.gov (United States)

    Kyriazi, Maria; Alexandratou, Eleni; Yova, Dido; Rallis, Michail; Trebst, Tilmann

    2007-07-01

    The aim of this work is to study pharmacokinetics and photodynamic efficiency of aluminium phthalocyanine chloride (AlClPc) in dimethylsulfoxide/Tween 80/water solution, after topical application on hairless mice bearing non-melanoma skin carcinomas. The concentration of photosensitizer in normal skin and tumor biopsies 1-6 hours after application was assessed by fluorescence spectroscopy of chemical extractions. The concentration of photosensitizer was 40 times higher in tumor than in normal skin even 1 h after application. For photodynamic therapy (PDT) AlClPc was excited by a diode laser emitting at 670 nm, 1 h after application. Seven different combinations of therapeutic parameters were chosen. The efficiency was assessed as the percentage of complete tumor remission, the tumor growth retardation and the cosmetic outcomes. The highest complete remission 60% was achieved with the combination of 75 mW/cm2 with 150 J/cm2. No recurrence rate was observed in any treatment parameters group and the cosmetic outcome in all completely treated tumors was excellent. The results show that the effectiveness of PDT is highly dependent on fluence rate. In addition, they are promising for further investigation of this PDT scheme in preclinical studies mainly in non-melanoma skin carcinomas up to 7mm.

  8. Evaluation of Direct Diode Laser Deposited Stainless Steel 316L on 4340 Steel Substrate for Aircraft Landing Gear Application

    Science.gov (United States)

    2010-03-01

    AFRL-RX-WP-TP-2010-4149 EVALUATION OF DIRECT DIODE LASER DEPOSITED STAINLESS STEEL 316L ON 4340 STEEL SUBSTRATE FOR AIRCRAFT LANDING GEAR...March 2010 – 01 March 2010 4. TITLE AND SUBTITLE EVALUATION OF DIRECT DIODE LASER DEPOSITED STAINLESS STEEL 316L ON 4340 STEEL SUBSTRATE FOR...Code) N/A Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39-18 Evaluation of Direct Diode Laser Deposited Stainless Steel 316L on

  9. Arbitrary waveform generator to improve laser diode driver performance

    Science.gov (United States)

    Fulkerson, Jr, Edward Steven

    2015-11-03

    An arbitrary waveform generator modifies the input signal to a laser diode driver circuit in order to reduce the overshoot/undershoot and provide a "flat-top" signal to the laser diode driver circuit. The input signal is modified based on the original received signal and the feedback from the laser diode by measuring the actual current flowing in the laser diode after the original signal is applied to the laser diode.

  10. Efficient Hybrid White Organic Light-Emitting Diodes for Application of Triplet Harvesting with Simple Structure

    CERN Document Server

    Hwang, Kyo Min; Lee, Sungkyu; Yoo, Han Kyu; Baek, Hyun Jung; Kim, Jwajin; Yoon, Seung Soo; Kim, Young Kwan

    2016-01-01

    In this study, we fabricated hybrid white organic light-emitting diodes (WOLEDs) based on triplet harvesting with simple structure. All the hole transporting material and host in emitting layer (EML) of devices were utilized with same material by using N,N'-di-1-naphthalenyl-N,N'-diphenyl-[1,1':4',1":4",1"'-quaterphenyl]-4,4"'-diamine (4P-NPD) which were known to be blue fluorescent material. Simple hybrid WOLEDs were fabricated three color with blue fluorescent and green, red phosphorescent materials. We was investigated the effect of triplet harvesting (TH) by exciton generation zone on simple hybrid WOLEDs. Characteristic of simple hybrid WOLEDs were dominant hole mobility, therefore exciton generation zone was expected in EML. Additionally, we was optimization thickness of hole transporting layer and electron transporting layer was fabricated a simple hybrid WOLEDs. Simple hybrid WOLED exhibits maximum luminous efficiency of 29.3 cd/A and maximum external quantum efficiency of 11.2%. Commission Internatio...

  11. Recent advance in tunable diode laser spectroscopy with background RAM nulling for industrial applications

    Science.gov (United States)

    Ruxton, Keith; Chakraborty, Arup Lal; McGettrick, Andrew J.; Duffin, Kevin; Johnstone, Walter; Stewart, George

    2009-10-01

    A limiting factor of tuneable diode laser spectroscopy (TDLS) with wavelength modulation spectroscopy (WMS) is the presence of background residual amplitude modulation (RAM) on the recovered 1st harmonic signal. The presence of this background term is due to direct modulation of the source laser power. This work presents a novel method to optically remove the unwanted background, with the major benefit being that measurement sensitivity can be increased. The recently developed phasor decomposition method1 (PDM), is a near IR (NIR) TDLS analysis technique that is used with the addition of the new RAM nulling method to recover gas absorption line-shapes. The PDM is a calibration free approach, which recovers the gas absorption line-shape and the isolated 1st derivative of the line-shape from the 1st harmonic signal. The work presented illustrates and validates the new RAM nulling procedure with measurements examining the 1650.96nm absorption line of methane (CH4) with comparisons to theory.

  12. Transparent conductive oxide films embedded with plasmonic nanostructure for light-emitting diode applications.

    Science.gov (United States)

    Chuang, Shih-Hao; Tsung, Cheng-Sheng; Chen, Ching-Ho; Ou, Sin-Liang; Horng, Ray-Hua; Lin, Cheng-Yi; Wuu, Dong-Sing

    2015-02-04

    In this study, a spin coating process in which the grating structure comprises an Ag nanoparticle layer coated on a p-GaN top layer of InGaN/GaN light-emitting diode (LED) was developed. Various sizes of plasmonic nanoparticles embedded in a transparent conductive layer were clearly observed after the deposition of indium tin oxide (ITO). The plasmonic nanostructure enhanced the light extraction efficiency of blue LED. Output power was 1.8 times the magnitude of that of conventional LEDs operating at 350 mA, but retained nearly the same current-voltage characteristic. Unlike in previous research on surface-plasmon-enhanced LEDs, the metallic nanoparticles were consistently deposited over the surface area. However, according to microstructural observation, ITO layer mixed with Ag-based nanoparticles was distributed at a distance of approximately 150 nm from the interface of ITO/p-GaN. Device performance can be improved substantially by using the three-dimensional distribution of Ag-based nanoparticles in the transparent conductive layer, which scatters the propagating light randomly and is coupled between the localized surface plasmon and incident light internally trapped in the LED structure through total internal reflection.

  13. Applications and limitations of a rheology for granular flows

    Science.gov (United States)

    Cawthorn, Chris; Hinch, John; Huppert, Herbert

    2007-11-01

    In order to assess the validity of the rheological law for granular flows proposed by Jop, Pouliquen and Forterre [Nature, vol. 441, pp.727-730], we present its application to a number of different problems. Whilst it works well for steady flow on a confined sandpile, or in an inclined channel, we will show that the law fails to qualitatively predict flow some simple geometries, such as annular Couette flow and vertical chute flow. In addition, we consider perturbations to 2D flow on an inclined plane and 3D flow in an inclined channel, where the effect of the confining vertical walls becomes important. Implications for the use of Jop's rheology for more complicated problems, particularly those involving dam-break or column collapse will also be addressed.

  14. Theory and Applications of Unsteady Flows

    Science.gov (United States)

    1979-07-05

    unsteady boundary-layer solutions with flow reversal, Dr. Wang, a post- doctoral research associate for two years, produced further examples in the...Donnelen, L. L., "Transient Response of Thick Airfoil with inite Trailing Edge Anigle in a Compressible Fluid," Ph.D. ’ Tesis , Cornell University, 1 979

  15. Application of tunable diode laser absorption spectroscopy in the detection of oxygen

    Science.gov (United States)

    Zhou, Xin; Jin, Xing

    2015-10-01

    Most aircrafts is driven by chemic energy which is released in the combustion process. For improving the capability of engine and controlling the running on-time, the processes of fuel physics and chemistry need to be analysis by kinds of high quality sensor. In the research of designing and improving the processes of fuel physics and chemistry, the concentration, temperature and velocity of kinds of gas in the combustor need to be detected and measured. In addition, these engines and research equipments are always in the harsh environment of high temperature, high pressure and high speed. The harsh environment needs the sensor to be high reliability, well repetition, no cross- sensitivity between gases, and the traditional measurement system can't satisfy the metrical requirement well. Tunable diode laser absorption spectroscopy (TDLAS) analytic measurement technology can well satisfy the measurement in the harsh environment, which can support the whole measurement plan and high quality measurement system. Because the TDLAS sensor has the excellence of small bulk, light weight, high reliability and well specifically measurement, the TDLAS measurement technology has wide prospects. Different from most measurements, only a beam of laser can be pass through the measured environment by TDLAS, and the measurement equipment needn't be set in the harsh environment. So, the TDLAS equipment can't be interrupted by the measured equipment. The ability of subsistence in the harsh environment is very valuable, especially in the measurement on the subject of aerospace with environment of high speed, combustion and plasma. This paper focuses on the collecting the articles on the subject of oxygen detection of TDLAS. By analyzing the research and results of the articles, we conclude the central issues, difficulties and results. And we can get some instructive conclusions.

  16. Gallium phosphide high temperature diodes

    Science.gov (United States)

    Chaffin, R. J.; Dawson, L. R.

    1981-01-01

    High temperature (300 C) diodes for geothermal and other energy applications were developed. A comparison of reverse leakage currents of Si, GaAs, and GaP was made. Diodes made from GaP should be usable to 500 C. A Liquid Phase Epitaxy (LPE) process for producing high quality, grown junction GaP diodes is described. This process uses low vapor pressure Mg as a dopant which allows multiple boat growth in the same LPE run. These LPE wafers were cut into die and metallized to make the diodes. These diodes produce leakage currents below ten to the -9th power A/sq cm at 400 C while exhibiting good high temperature rectification characteristics. High temperature life test data is presented which shows exceptional stability of the V-I characteristics.

  17. Flow Battery Solution for Smart Grid Applications

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2014-11-30

    To address future grid requirements, a U.S. Department of Energy ARRA Storage Demonstration program was launched in 2009 to commercialize promising technologies needed for stronger and more renewables-intensive grids. Raytheon Ktech and EnerVault received a cost-share grant award from the U.S. Department of Energy to develop a grid-scale storage system based on EnerVault’s iron-chromium redox flow battery technology.

  18. Gerris Flow Solver: Implementation and Application

    Science.gov (United States)

    2013-05-12

    processes include the interaction of clay particles with turbulent flows driven by tides and waves. This study thus reinforces the lesson that...boundaries. Journal of Fluid Mechanics, 418:189-212. Lindgren, E.R. 1956. Properties of Certain Bentonite Suspensions and water—a note on the...of sediment will be parameterized for several classes of materiel, including sand, clay , and organic detritus. Processing input Once an autoCAD

  19. Vertical current-flow enhancement via fabrication of GaN nanorod p–n junction diode on graphene

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Sung Ryong [Quantum-functional Semiconductor Research Center, Dongguk University-Seoul, 100-715 (Korea, Republic of); Department of physics, Dongguk University, Seoul, 100-715 (Korea, Republic of); Ram, S.D. Gopal; Lee, Seung Joo; Cho, Hak-dong; Lee, Sejoon [Quantum-functional Semiconductor Research Center, Dongguk University-Seoul, 100-715 (Korea, Republic of); Kang, Tae Won, E-mail: twkang@dongguk.edu [Quantum-functional Semiconductor Research Center, Dongguk University-Seoul, 100-715 (Korea, Republic of); Clean Energy and Nano Convergence Centre, Hindustan University, Chennai 600 016 (India); Kwon, Sangwoo; Yang, Woochul [Department of physics, Dongguk University, Seoul, 100-715 (Korea, Republic of); Shin, Sunhye [Soft-Epi Inc., 240 Opo-ro, Opo-eup, Gwangju-si, Gyeonggi-do (Korea, Republic of); Woo, Yongdeuk [Department of Mechanical and Automotive Engineering, Woosuk University, Chonbuk 565-701 (Korea, Republic of)

    2015-08-30

    Highlights: • Uniaxial p–n junction diode in GaN nanorod is made by Hydride vapor phase epitaxy method. • The p–n junction diode property is clearly observed from the fabricated uniaxial p–n junction nanorod GaN nanorod. • Graphene is used as a current spreading layer to reduce the lateral resistance up to 700 times when compared with the commercial sapphire substrate, which is clearly explained with the aid of an equivalent circuit. • Kelvin Force Probe microscopy method is employed to visualize the p- and n- regions in a single GaN nanorod. - Abstract: Mg doped GaN nanorods were grown on undoped n-type GaN nanorods uniaxial on monolayer graphene by hydride vapor phase epitaxy (HVPE) method. The monolayer graphene used as the bottom electrode and a substrate as well provides good electrical contact, acts as a current spreading layer, well suitable for the growth of hexagonal GaN nanorod. In addition it has a work function suitable to that of n-GaN. The formed p–n nanorods show a Schottky behavior with a turn on voltage of 3 V. Using graphene as the substrate, the resistance of the nanorod is reduced by 700 times when compared with the case without using graphene as the current spreading layer. The low resistance of graphene acts in parallel with the resistance of the GaN buffer layer, and reduces the resistance drastically. The formed p–n junction in a single GaN nanorod is visualized by Kelvin Force Probe Microscopy (KPFM) to have distinctively contrast p and n regions. The measured contact potential difference of p-and n-region has a difference of 103 mV which well confirms the formed regions are electronically different. Low temperature photoluminescence (PL) spectra give evidence of dopant related acceptor bound emission at 3.2 eV different from 3.4 eV of undoped GaN. The crystalline structure, compositional purity is confirmed by X-ray diffraction (XRD), Transmission and Scanning electron microcopies (SEM), (TEM), Energy dispersive analysis

  20. n-(CdMgTe/CdTe)/(p-(CdTe/ZnCdTe/ZnTe)/p-GaAs heterostructure diode for photosensor applications

    Science.gov (United States)

    Yahia, I. S.; AlFaify, S.; Abutalib, M. M.; Chusnutdinow, S.; Wojtowicz, T.; Karczewski, G.; Yakuphanoglu, F.; Al-Bassam, A.; El-Naggar, A. M.; El-Bashir, S. M.

    2016-05-01

    High quality n-(CdMgTe:I/n-CdTe:I)/(p-CdTe:N/p-ZnCdTe:N/p-ZnTe:N)/p-GaAs heterojunction diodes have been fabricated by molecular beam epitaxial growth. The illumination effect on the complex impedance and conductivity of heterostructure diode was investigated. The illumination intensities were taken up to the 200 mW/cm2 with frequency range of 42 Hz to 1 MHz. The observed real and imaginary parts of the complex impedance were strongly dependent on the illumination frequency. The inverse relation was observed between the illumination intensity and the complex impedance. The relaxation mechanism of the diode was analyzed by the Cole-Cole plots. The radius of the Cole-Cole curve decreases with increasing illumination intensity. This suggests a mechanism of illumination dependent on the relaxation process. It is also found that the conductivity increases linearly with increasing the illumination intensity. We can conclude that the new design heterostructure diode in our work is a good candidate in photodetector and optoelectronic applications.

  1. Study of optimization of Al/a-SiC:H Schottky diodes by means of annealing process of a-SiC:H thin films sputtered at three different hydrogen flow rates

    Directory of Open Access Journals (Sweden)

    L. Magafas

    2008-01-01

    Full Text Available The aim of the present work is to study the optimization of the electrical and optical properties of a-SiC:H Schottky di-odes using thermal annealing process to a-SiC:H thin films in the range from 300oC up to 675oC. The films were depos-ited onto c-Si(n using the rf sputtered method at three different hydrogen flow rates, 9sccm, 14sccm, and 20sccm. Sub-sequently, Al dots evaporated onto a-SiC:H in order to form Schottky contacts. The measurements of logI-V character-istics have shown that the Al/a-SiC:H Schottky diodes are optimized at 550oC, 575oC, and 600oC , for hydrogen flow rates 9 sccm, 14 sccm and 20 sccm respectively. At these temperatures the logI-V curves are linear for more than seven orders of magnitude, and the majority carries are transported by thermal emission mechanism. The measurements of op-tical response of these diodes present two maximum values (>70%, one in the range from 550nm up to 625nm and the other at 850nm which are attributed to Al/a-SiC:H junction and to a-SiC:H/c-Si(n heterojunction, respectively. From the overall study of the electrical and optical measurements of the Schottky diodes it is concluded that at hydrogen flow rate 20 sccm and annealing temperature 600oC is achieved the optimum Al/a-SiC:H Schottky diode. This result is in full agreement with the properties of the a-SiC:H.

  2. Application of a diode array spectroradiometer to measuring the spectral scattering properties of cloud types in a laboratory

    Directory of Open Access Journals (Sweden)

    A. R. D. Smedley

    2007-11-01

    Full Text Available In the last few years diode array spectroradiometers have become useful complements to traditional scanning instruments when measuring visible and ultraviolet solar radiation incident on the ground. This study describes the application of such an instrument to the problem of measuring the radiation scattered by different cloud-types in a laboratory environment. Details of how the instrument is incorporated into the experimental set-up are given together with the development of the system as a whole. The capability to measure a full spectrum for each scattering angle is an undoubted advantage, although the limited sensitivity impacts on the usefulness for optically thin clouds. Nevertheless example results are presented: (1 scattering phase functions at a range of wavelengths recorded simultaneously for water clouds, showing spectral deviation at the rainbow angle and verification of Mie theory; (2 likewise for mixed phase clouds, with evidence of both halo and rainbow features in a single scattering function; and, (3 detail of the forward scattering region in a glaciated cloud showing a barely perceptible halo feature, with implications for the small-scale structure of the ice crystals produced.

  3. Application of a diode array spectroradiometer to measuring the spectral scattering properties of cloud types in a laboratory

    Directory of Open Access Journals (Sweden)

    A. R. D. Smedley

    2007-07-01

    Full Text Available In the last few years diode array spectroradiometers have become useful complements to traditional scanning instruments when measuring visible and ultraviolet solar radiation incident on the ground. This study describes the application of such an instrument to the problem of measuring the radiation scattered by different cloud types in a laboratory environment. Details of how the instrument is incorporated into the experimental set-up are given together with the development of the system as a whole. The capability to measure a full spectrum for each scattering angle is an undoubted advantage, although the limited dynamic range impacts on the usefulness for optically thin clouds. Nevertheless example results are presented: (1 scattering phase functions at a range of wavelengths recorded simultaneously for water clouds, showing spectral deviation at the rainbow angle and verification of Mie theory; (2 likewise for mixed phase clouds, with evidence of both halo and rainbow features in a single scattering function; and, (3 detail of the forward scattering region in a glaciated cloud showing a barely perceptible halo feature, with implications for the small-scale structure of the ice crystals produced.

  4. High-Quality Growth of GaInNAs for Application to Near-Infrared Laser Diodes

    Directory of Open Access Journals (Sweden)

    Masahiko Kondow

    2012-01-01

    Full Text Available GaInNAs was proposed and created in 1995. It can be grown pseudomorphically on a GaAs substrate and is a light-emitting material with a bandgap energy that corresponds to near infrared. By combining GaInNAs with GaAs, an ideal band lineup for laser-diode application is achieved. This paper presents the reproducible growth of high-quality GaInNAs by molecular beam epitaxy. Examining the effect of nitrogen introduction and its correlation with impurity incorporation, we find that Al is unintentionally incorporated into the epitaxial layer even though the Al cell shutter is closed, followed by the concomitant incorporation of O and C. A gas-phase-scattering model can explain this phenomenon, suggesting that a large amount of N2 gas causes the scattering of residual Al atoms with occasional collisions resulting in the atoms being directed toward the substrate. Hence, the reduction of the sublimated Al beam during the growth period can suppress the incorporation of unintentional impurities, resulting in a highly pure epitaxial layer.

  5. Direct bandgap GeSn light emitting diodes for short-wave infrared applications grown on Si

    Science.gov (United States)

    von den Driesch, Nils; Stange, Daniela; Wirths, Stephan; Rainko, Denis; Mussler, Gregor; Stoica, Toma; Ikonic, Zoran; Hartmann, Jean-Michel; Grützmacher, Detlev; Mantl, Siegfried; Buca, Dan

    2016-03-01

    The experimental demonstration of fundamental direct bandgap, group IV GeSn alloys has constituted an important step towards realization of the last missing ingredient for electronic-photonic integrated circuits, i.e. the efficient group IV laser source. In this contribution, we present electroluminescence studies of reduced-pressure CVD grown, direct bandgap GeSn light emitting diodes (LEDs) with Sn contents up to 11 at.%. Besides homojunction GeSn LEDs, complex heterojunction structures, such as GeSn/Ge multi quantum wells (MQWs) have been studied. Structural and compositional investigations confirm high crystalline quality, abrupt interfaces and tailored strain of the grown structures. While also being suitable for light absorption applications, all devices show light emission in a narrow short-wave infrared (SWIR) range. Temperature dependent electroluminescence (EL) clearly indicates a fundamentally direct bandgap in the 11 at.% Sn sample, with room temperature emission at around 0.55 eV (2.25 µm). We have, however, identified some limitations of the GeSn/Ge MQW approach regarding emission efficiency, which can be overcome by introducing SiGeSn ternary alloys as quantum confinement barriers.

  6. 半导体激光在牙周治疗中的临床应用%Clinical application of the diode laser in periodontal therapy

    Institute of Scientific and Technical Information of China (English)

    赵静(综述); 李新月(审校)

    2016-01-01

    半导体激光从20世纪90年代中期开始用于口腔治疗,半导体激光具有高效率,体积小,寿命长,波长可选择,成本低,使用简便,创伤小,患者术后反应小等特点。目前,半导体激光已应用于牙周基础治疗,牙周手术治疗,牙周病的伴发病变--牙本质敏感等牙周治疗,半导体激光在牙周病的治疗中起到越来越重要的作用。本文将就半导体激光用于牙周治疗的临床应用做一综述。%Diode laser century began to be used for dental treatment from the mid-90s of the 20th. Diode laser has the advantages of high efficiency, small volume, long life, wave length selectable,low cost, easy to use, small trauma, and the patients with small postoperative reaction.Currently diode laser has been applied in periodontal non-surgery treatment, periodontal surgery treatment and treatment of periodontal disease accompanying lesions-- dentin sensitivity. Diode laser plays a more and more important role in the treatment of periodontal disease. This paper will review the clinical application of the diode laser.

  7. Studies on high power ultrasonic microembossing and organic light emitting diodes (OLEDs) for the creation of lab-on-CD devices for sensor related applications

    Science.gov (United States)

    Vengasandra, Srikanth G.

    This study demonstrates the application of High Power Ultrasonic Microembossing Technology (HPUMT) in producing microfeatures on polymer substrates. The work reviews a novel method of obtaining flash free and precise microfeatures by manipulating the material density through microcellular foaming. The microfeatures created on the polymer substrates were further characterized by analyzing the feature depth with respect to the critical ultrasonic embossing operating parameters such as embossing heating times (s), embossing amplitude (microm) at a constant embossing trigger force (N). An experiment design was constructed and performed to characterize the parameters on foamed and unfoamed (or regular) versions of polystyrene (PS) and polypropylene (PP) sample materials. Results indicated feature depth was proportional to heating times, amplitude and force. It was also seen the maximum depth was achieved in the shortest cycle times with higher amplitudes and forces of operation. HPUMT was further studied to create functional network of microchannels functioned as reservoirs, reaction chamber and burst or gate valves to form a centrifugal biosensing platform that is also referred to as a lab-on-CD or a bio-CD device. The surface energy of the polymer substrates was increased to enable fluid flow by using a surfactant based organic coating to facilitate hydrophilicity. Using an organic light emitting diode (OLEDs) as an electroluminescence source provided luminescence decay results in good agreement with stern-volmer relationship. The functionality of the OLED-coupled lab-on-CD device was further tested in measuring unknown concentrations of a particular analyte in corn slurry sample which contained numerous contaminants. Combinatorial multianalyte sensing was also made possible on a single bio-CD using a four photodetector (PD) quad preamp disk sensor.

  8. Investigations on the potential of a novel diode pumped Er:YAG laser system for dental applications

    Science.gov (United States)

    Stock, Karl; Hausladen, Florian; Hibst, Raimund

    2012-01-01

    The successful clinical application of the Er:YAG-laser in dentistry is well known, documented by numerous published studies. These lasers are flash lamp pumped systems and emit pulses of typically some 100 μs duration with energies of up to 1 J. Pulse repetition rates can reach up to 100Hz, and mean powers are up to about 8W. As an alternative to these laser systems recently a novel diode pumped Er:YAG laser system (Pantec Engineering AG) became available. This laser can provide a pulse repetition rate up to 2kHz and a mean laser power up to 15W. The aim of the presented study is to investigate the effect of this laser system on dental hard and soft tissue at various irradiation parameters, particular at repetition rates more than 100 Hz. At first an appropriate experimental set-up was realized with a beam delivery and focusing unit, a computer controlled stepper unit with sample holder, and a shutter unit. The stepper unit allows to move the samples (dentin or enamel slides of extracted human teeth, chicken breast, pig bone) with a defined velocity during irradiation by various laser parameters. For rinsing the sample surface a water spray was also included. The laser produced grooves and cuts were analyzed by light microscopy and laser scanning microscopy regarding to the ablation quality, geometry, ablation efficacy, and thermal effects. The grooves in dentin and enamel show a rough surface, typical for Er:YAG laser ablation. The craters are slightly cone shaped with sharp edges on the surface. Water cooling is essential to prevent thermal injury. The ablation efficacy in dentin is comparable to literature values of the flash lamp pumped Er:YAG laser. The cutting of bone and soft tissue is excellent and appears superior to earlier results obtained with flash lamp pumped system. As a further advantage, the broad range of repetition rates allows to widely vary the thermal side effects. In conclusion, these first experiments with a diode pumped Er:YAG laser

  9. Development and Application of Flow Duration Curves for Stream Restoration

    Science.gov (United States)

    2016-02-01

    They have traditionally been used for a variety of purposes from hydropower engineering to instream flow quantification. This paper serves to (1...play disproportionately large roles in shaping ERDC TN-EMRRP-SR-49 February 2016 8 channel morphology by doing the most “geomorphic work ” over...Discharge Probability Sediment Rating (ton/da) Geomorphic Work Figure 6. Effective discharge application of flow duration curves for the Etowah River at

  10. Modeling Ultraviolet (UV) Light Emitting Diode (LED) Energy Propagation in Reactor Vessels

    Science.gov (United States)

    2014-03-27

    urban wastewater effluent than a single wavelength used alone (Chevremont, Farnet, Coulomb, & Boudenne, 2012; Oguma, Kita, Sakai, Murakami ...j.jcrysgro.2004.04.071 Oguma, K., Kita, R., Sakai, H., Murakami , M., & Takizawa, S. (2013). Application of UV light emitting diodes to batch and flow

  11. Energy flow theory of nonlinear dynamical systems with applications

    CERN Document Server

    Xing, Jing Tang

    2015-01-01

    This monograph develops a generalised energy flow theory to investigate non-linear dynamical systems governed by ordinary differential equations in phase space and often met in various science and engineering fields. Important nonlinear phenomena such as, stabilities, periodical orbits, bifurcations and chaos are tack-led and the corresponding energy flow behaviors are revealed using the proposed energy flow approach. As examples, the common interested nonlinear dynamical systems, such as, Duffing’s oscillator, Van der Pol’s equation, Lorenz attractor, Rössler one and SD oscillator, etc, are discussed. This monograph lights a new energy flow research direction for nonlinear dynamics. A generalised Matlab code with User Manuel is provided for readers to conduct the energy flow analysis of their nonlinear dynamical systems. Throughout the monograph the author continuously returns to some examples in each chapter to illustrate the applications of the discussed theory and approaches. The book can be used as ...

  12. Malformaciones venosas orofaciales de bajo flujo: esclerosis endoluminal con láser de diodo Low-flow orofacial venous malformations: endoluminal sclerosis with a diode laser

    Directory of Open Access Journals (Sweden)

    M. Puche Torres

    2010-06-01

    of varicose veins. Our proposal is the usage of diode laser (l = 980 nm to induce the sclerosis of low-flow venous malformations by intralesional photocoagulation, given this laser's ability to deliver the beam via a fiber optic cable. Objective: To report our results in the treatment of orofacial low-flow venous malformations (LFVM with diode laser endovenous sclerosis (DLES. Material and methods: The clinical records from 84 patients presenting with orofacial LFVM treated with DLES were collected. The technique used and short-term postoperative results were revised. Results: After a follow-up period of at least 12 months after one or two DLES sessions, healing was observed in 95.24% of the cases. Only 4 cases showed relapse. Conclusions: The DLES technique is a new therapeutic option for the treatment of orofacial LFVM, is minimally-invasive, allows an outpatient setting and achieves excellent functional and esthetic results avoiding more aggressive procedures.

  13. Applications the Lagrangian description in aperiodic flows

    Science.gov (United States)

    Mendoza, Carolina; Mancho, Ana Maria

    2012-11-01

    We use several recently developed Lagrangian tools for describing transport in general aperiodic flows. In our approach the first step is based in a Lagrangian descriptor (the so called function M). It measures the length of particle trajectories on the ocean surface over a given interval of time. We describe its output over satellite altimetry data on the Kuroshio current. The technique is combined with the direct computation of manifolds of Distinguished Hyperbolic trajectories and a very detailed description of transport is achieved across an eddy and a jet on the Kuroshio current,. A second velocity data set is examined with the M function tool. These are obtained from the HYCOM project on the Gulf of Mexico during the time of the oil-spill. We have identified underlying Lagrangian structures and dynamics. We acknowledge to the hospitality of the university of Delaware and the assistance of Bruce Lipphardt and Helga Huntley in accessing the model data sets. We acknowledge to the grants: UPM-AL12-PAC-09, Becas de Movilidad de Caja Madrid 2011, MTM2011-26696 and ILINK-0145.

  14. Light-emitting diode applications of colloidal CdSe/ZnS quantum dots embedded in TiO{sub 2-{delta}} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Seung-Hee; Huh, Hoon-Hoe; Son, Kee-Chul; Kim, Eui-Tae [Department of Materials Engineering, Chungnam National University, Daeduk Science Town, Daejeon (Korea); Lee, Chang-Soo [Department of Chemical Engineering, Chungnam National University, Daeduk Science Town, Daejeon (Korea); Kim, Kyung-Hyun; Huh, Chul [Electronics and Telecommunications Research Institute, Daeduk Science Town, Daejeon (Korea)

    2009-04-15

    We report the light-emitting diode (LED) characteristics of colloidal core-shell CdSe/ZnS nanocrystal quantum dots (QDs) embedded in TiO{sub 2-{delta}} thin films on Si substrate. High-quality CdSe/ZnS QDs were synthesized via a pyrolysis in the range of 220-280 C. The QDs were embedded in TiO{sub 2-{delta}} thin film at 200 C by plasma-enhanced metallorganic chemical vapor deposition. The diode structure of n-TiO{sub 2-{delta}}/QDs/p-Si showed electroluminescence characteristics, indicating the possibility of LED applications of colloidal CdSe/ZnS nanocrystal QDs embedded in oxide films on large-area Si wafer. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. ZVZCS Based High Frequency Link Grid Connected SVM applied Three Phase Three Level Diode Clamped Inverter for Photovoltaic Applications Part-II

    Directory of Open Access Journals (Sweden)

    Soumyadeep Ray

    2014-07-01

    Full Text Available This article proposes a newly proposed highly effective Zero Voltage and Zero Current switching based Front end converter with a High Frequency Transformer with a Three Phase Three Level Diode Clamped Inverter in photovoltaic applications. The switching scheme is implemented in MATLAB/ Simulink condition. ZVZCS condition is achieved. This type of converter shows high efficiency and very negligible switching loss. Finally ZVZCS based High Frequency Link Diode Clamped Inverter is connected to Grid. An MCI optimized Current controller is used with SVM switching technique.  In This article, responses with three types of controllers (I, PI, PID have been examined and compared. Simulation results show the effectiveness, and validity of this technique.

  16. High-power one-, two-, and three-dimensional photonic crystal edge-emitting laser diodes for ultra-high brightness applications

    Science.gov (United States)

    Gordeev, N. Yu.; Maximov, M. V.; Shernyakov, Y. M.; Novikov, I. I.; Karachinsky, L. Ya.; Shchukin, V. A.; Kettler, T.; Posilovic, K.; Ledentsov, N. N.; Bimberg, D.; Duboc, R.; Sharon, A.; Arbiv, D. B.; Ben-Ami, U.

    2008-02-01

    Direct laser diodes can typically provide only a limited single mode power, while ultrahigh-brightness is required for many of the market-relevant applications. Thus, multistage power conversion schemes are applied, when the laser diodes are used just as a pumping source. In this paper we review the recent advances in ultra-large output aperture edge-emitting lasers based on the photonic band crystal (PBC) concept. The concept allows near- and far-field engineering robust to temperature and strain gradients and growth nonuniformities. High-order modes are selectively filtered and the effective optical confinement of the fundamental mode can be dramatically enhanced. At first, we show that robust ultra-narrow vertical beam divergence (operation by processing of the multistripe arrays along their lengths. The concept opens a way for 3D photonic crystal edge emitting lasers potentially allowing scalable single mode power increase to arbitrary high levels.

  17. Complex analysis with applications to flows and fields

    CERN Document Server

    Braga da Costa Campos, Luis Manuel

    2012-01-01

    Complex Analysis with Applications to Flows and Fields presents the theory of functions of a complex variable, from the complex plane to the calculus of residues to power series to conformal mapping. The book explores numerous physical and engineering applications concerning potential flows, the gravity field, electro- and magnetostatics, steady heat conduction, and other problems. It provides the mathematical results to sufficiently justify the solution of these problems, eliminating the need to consult external references.The book is conveniently divided into four parts. In each part, the ma

  18. Diagnostic and therapeutic applications of diode lasers and solid state lasers in medicine. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S.L. [Texas Univ., Houston, TX (United States). Cancer Center; Welch, A.J. [Texas Univ., Austin, TX (United States); Motamedi, M. [Texas Univ., Galveston, TX (United States). Medical Branch; Rastegar, S. [Texas A and M Univ., College Station, TX (United States); Tittel, F. [Rice Univ., Houston, TX (United States); Esterowitz, L. [Naval Research Lab., Washington, DC (United States)

    1992-05-01

    The Texas Medical Center in Houston and the nearby UT Medical Branch at Galveston together constitute a major center of medical research activities. Laser applications in medicine are under development with the engineering assistance of the colloborating engineering centers at Rice University, UT-Austin, and Texas A&M Univ. In addition, this collective is collaborating with the Naval Research Laboratory, where new developments in laser design are underway, in order to transfer promising new laser technology rapidly into the medical environment.

  19. Diagnostic and therapeutic applications of diode lasers and solid state lasers in medicine

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S.L. (Texas Univ., Houston, TX (United States). Cancer Center); Welch, A.J. (Texas Univ., Austin, TX (United States)); Motamedi, M. (Texas Univ., Galveston, TX (United States). Medical Branch); Rastegar, S. (Texas A and M Univ., College Station, TX (United States)); Tittel, F. (Rice Univ., Houston, TX (United States)); Esterowitz, L. (Naval Research Lab., Washington, DC (United States))

    1992-05-01

    The Texas Medical Center in Houston and the nearby UT Medical Branch at Galveston together constitute a major center of medical research activities. Laser applications in medicine are under development with the engineering assistance of the colloborating engineering centers at Rice University, UT-Austin, and Texas A M Univ. In addition, this collective is collaborating with the Naval Research Laboratory, where new developments in laser design are underway, in order to transfer promising new laser technology rapidly into the medical environment.

  20. Diagnostic and therapeutic applications of diode lasers and solid state lasers in medicine. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S.L. [Texas Univ., Houston, TX (United States). Cancer Center; Welch, A.J. [Texas Univ., Austin, TX (United States); Motamedi, M. [Texas Univ., Galveston, TX (United States). Medical Branch; Rastegar, S. [Texas A and M Univ., College Station, TX (United States); Tittel, F. [Rice Univ., Houston, TX (United States); Esterowitz, L. [Naval Research Lab., Washington, DC (United States)

    1993-05-01

    The Texas Medical Center in Houston and the nearby UT Medical Branch at Galveston together constitute a major center of medical research activities. Laser applications in medicine are under development with the engineering assistance of the collaborating engineering enters at Rice University, UT-Austin, Texas A&M Univ. In addition, this collective is collaborating with the naval Research Laboratory, where new developments in laser design are underway, in order to transfer promising new laser technology rapidly into the medical environment.

  1. SiC-based Schottky diode gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, G.W.; Neudeck, P.G.; Chen, L.Y. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center; Knight, D. [Cortez/NASA Lewis Research Center, Cleveland, OH (United States); Liu, C.C.; Wu, Q.H. [Electronics Design Center, Case Western Reserve Univ., Cleveland, OH (United States)

    1998-08-01

    Silicon carbide based Schottky diode gas sensors are being developed for high temperature applications such as emission measurements. Two different types of gas sensitive diodes will be discussed in this paper. By varying the structure of the diode, one can affect the diode stability as well as the diode sensitivity to various gases. It is concluded that the ability of SiC to operate as a high temperature semiconductor significantly enhances the versatility of the Schottky diode gas sensing structure and will potentially allow the fabrication of a SiC-based gas sensor array for versatile high temperature gas sensing applications. (orig.) 6 refs.

  2. SiC-Based Schottky Diode Gas Sensors

    Science.gov (United States)

    Hunter, Gary W.; Neudeck, Philip G.; Chen, Liang-Yu; Knight, Dak; Liu, Chung-Chiun; Wu, Quing-Hai

    1997-01-01

    Silicon carbide based Schottky diode gas sensors are being developed for high temperature applications such as emission measurements. Two different types of gas sensitive diodes will be discussed in this paper. By varying the structure of the diode, one can affect the diode stability as well as the diode sensitivity to various gases. It is concluded that the ability of SiC to operate as a high temperature semiconductor significantly enhances the versatility of the Schottky diode gas sensing structure and will potentially allow the fabrication of a SiC-based gas sensor arrays for versatile high temperature gas sensing applications.

  3. Design of compact freeform lens for application specific Light-Emitting Diode packaging.

    Science.gov (United States)

    Wang, Kai; Chen, Fei; Liu, Zongyuan; Luo, Xiaobing; Liu, Sheng

    2010-01-18

    Application specific LED packaging (ASLP) is an emerging technology for high performance LED lighting. We introduced a practical design method of compact freeform lens for extended sources used in ASLP. A new ASLP for road lighting was successfully obtained by integrating a polycarbonate compact freeform lens of small form factor with traditional LED packaging. Optical performance of the ASLP was investigated by both numerical simulation based on Monte Carlo ray tracing method and experiments. Results demonstrated that, comparing with traditional LED module integrated with secondary optics, the ASLP had advantages of much smaller size in volume (approximately 1/8), higher system lumen efficiency (approximately 8.1%), lower cost and more convenience for customers to design and assembly, enabling possible much wider applications of LED for general road lighting. Tolerance analyses were also conducted. Installation errors of horizontal and vertical deviations had more effects on the shape and uniformity of radiation pattern compared with rotational deviation. The tolerances of horizontal, vertical and rotational deviations of this lens were 0.11 mm, 0.14 mm and 2.4 degrees respectively, which were acceptable in engineering.

  4. Application of a one-dimensional TEC code to the characterization of a lanthanum-hexaboride diode

    Science.gov (United States)

    van Dam, Scott A.; Ramalingam, Mysore L.

    A one-dimensional thermionic energy conversion (TEC) computer code has been utilized to provide a theoretical basis of comparison for experimentally derived data obtained from a lanthanum hexaboride cesium vapor thermionic diode. Although the code-generated predictions obtained were not in precise agreement with the experimental results, they do provide a basis for establishing the validity of the experimental results from an analytical framework. Certain discrepancies are thus identified, and an attempt is made to account for them in terms of code inaccuracies and/or possible experimental error. Experimental lanthanum-hexaboride (LaB6) cesium-vapor TEC diode characteristics are compared to those predicted by the TEC code. The diode used was activated by electron-bombardment heating in a rejuvenated diode testing facility. A DOS loop and auxiliary Fortran program were used in conjunction with the original TEC code to generate both general and LaB6 simulated diode current density vs. output voltage characteristics. The effects of changing the emitter and collector work functions and the operating cesium-vapor pressure were studied for both cases.

  5. Lattice Boltzmann methods for complex micro-flows: applicability and limitations for practical applications

    Science.gov (United States)

    Suga, K.

    2013-06-01

    The extensive evaluation studies of the lattice Boltzmann method for micro-scale flows (μ-flow LBM) by the author's group are summarized. For the two-dimensional test cases, force-driven Poiseuille flows, Couette flows, a combined nanochannel flow, and flows in a nanochannel with a square- or triangular cylinder are discussed. The three-dimensional (3D) test cases are nano-mesh flows and a flow between 3D bumpy walls. The reference data for the complex test flow geometries are from the molecular dynamics simulations of the Lennard-Jones fluid by the author's group. The focused flows are mainly in the slip and a part of the transitional flow regimes at Kn flow LBMs are the lattice Bhatnagar-Gross-Krook and the multiple-relaxation time LBMs with several boundary conditions and discrete velocity models. The effects of the discrete velocity models, the wall boundary conditions, the near-wall correction models of the molecular mean free path and the regularization process are discussed to confirm the applicability and the limitations of the μ-flow LBMs for complex flow geometries.

  6. Lattice Boltzmann methods for complex micro-flows: applicability and limitations for practical applications

    Energy Technology Data Exchange (ETDEWEB)

    Suga, K, E-mail: suga@me.osakafu-u.ac.jp [Department of Mechanical Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan)

    2013-06-15

    The extensive evaluation studies of the lattice Boltzmann method for micro-scale flows ({mu}-flow LBM) by the author's group are summarized. For the two-dimensional test cases, force-driven Poiseuille flows, Couette flows, a combined nanochannel flow, and flows in a nanochannel with a square- or triangular cylinder are discussed. The three-dimensional (3D) test cases are nano-mesh flows and a flow between 3D bumpy walls. The reference data for the complex test flow geometries are from the molecular dynamics simulations of the Lennard-Jones fluid by the author's group. The focused flows are mainly in the slip and a part of the transitional flow regimes at Kn < 1. The evaluated schemes of the {mu}-flow LBMs are the lattice Bhatnagar-Gross-Krook and the multiple-relaxation time LBMs with several boundary conditions and discrete velocity models. The effects of the discrete velocity models, the wall boundary conditions, the near-wall correction models of the molecular mean free path and the regularization process are discussed to confirm the applicability and the limitations of the {mu}-flow LBMs for complex flow geometries. (invited review)

  7. Modelling of a cross flow evaporator for CSP application

    DEFF Research Database (Denmark)

    Sørensen, Kim; Franco, Alessandro; Pelagotti, Leonardo

    2016-01-01

    ) applications. Heat transfer and pressure drop prediction methods are an important tool for design and modelling of diabatic, two-phase, shell-side flow over a horizontal plain tubes bundle for a vertical up-flow evaporator. With the objective of developing a model for a specific type of cross flow evaporator....... The influence on the analysis of the performance of the evaporator, their impact on significant design variables and the effective lifetime of critical components in different operating conditions, simulating the daily start-up procedures of the steam generator is evaluated. The importance of a good calibration...... for a coil type steam generator specifically designed for solar applications, this paper analyzes the use of several heat transfer, void fraction and pressure drop correlations for the modelling the operation of such a type of steam generator. The paper after a brief review of the literature about...

  8. Laser diode self-mixing technique for liquid velocimetry

    Science.gov (United States)

    Alexandrova, A.; Welsch, C. P.

    2016-09-01

    Using the self-mixing technique, or optical feedback interferometry, fluid velocity measurements of water seeded with titanium dioxide have been performed using a laser diode to measure the effect of the seeding particle concentration and also the pump speed of the flow. The velocimeter utilises commercially available laser diodes with a built-in photodiode for detection of the self-mixing effect. The device has demonstrated an accuracy better than 10% for liquid flow velocities up to 1.5 m/s with a concentration of scattering particles in the range of 0.8-0.03%. This is an improvement of one order of magnitude compared to previous experiments. The proposed velocimeter is to be developed further for application in gas-jet measurements.

  9. Laser diode self-mixing technique for liquid velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrova, A., E-mail: a.alexandrova@liverpool.ac.uk [Cockcroft Institute, Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); University of Liverpool, Department of Physics, Liverpool L69 7ZE (United Kingdom); Welsch, C.P. [Cockcroft Institute, Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); University of Liverpool, Department of Physics, Liverpool L69 7ZE (United Kingdom)

    2016-09-11

    Using the self-mixing technique, or optical feedback interferometry, fluid velocity measurements of water seeded with titanium dioxide have been performed using a laser diode to measure the effect of the seeding particle concentration and also the pump speed of the flow. The velocimeter utilises commercially available laser diodes with a built-in photodiode for detection of the self-mixing effect. The device has demonstrated an accuracy better than 10% for liquid flow velocities up to 1.5 m/s with a concentration of scattering particles in the range of 0.8–0.03%. This is an improvement of one order of magnitude compared to previous experiments. The proposed velocimeter is to be developed further for application in gas-jet measurements.

  10. Some applications of magnetic resonance imaging in fluid mechanics: Complex flows and complex fluids

    NARCIS (Netherlands)

    Bonn, D.; Rodts, S.; Groenink, M.; Rafaï, S.; Shahidzadeh-Bonn, N.; Coussot, P.

    2008-01-01

    The review deals with applications of magnetic resonance imaging (MRI) techniques to study flow. We first briefly discuss the principles of flow measurement by MRI and give examples of some applications, such as multiphase flows, the MRI rheology of complex fluid flows, and blood flows in the human

  11. The Liang-Kleeman Information Flow: Theory and Applications

    Directory of Open Access Journals (Sweden)

    X. San Liang

    2013-01-01

    Full Text Available Information flow, or information transfer as it may be referred to, is a fundamental notion in general physics which has wide applications in scientific disciplines. Recently, a rigorous formalism has been established with respect to both deterministic and stochastic systems, with flow measures explicitly obtained. These measures possess some important properties, among which is flow or transfer asymmetry. The formalism has been validated and put to application with a variety of benchmark systems, such as the baker transformation, Hénon map, truncated Burgers-Hopf system, Langevin equation, etc. In the chaotic Burgers-Hopf system, all the transfers, save for one, are essentially zero, indicating that the processes underlying a dynamical phenomenon, albeit complex, could be simple. (Truth is simple. In the Langevin equation case, it is found that there could be no information flowing from one certain time series to another series, though the two are highly correlated. Information flow/transfer provides a potential measure of the cause–effect relation between dynamical events, a relation usually hidden behind the correlation in a traditional sense.

  12. Flow Cooling of Superconducting Magnets for Spacecraft Applications

    Science.gov (United States)

    Dietz, A. J.; Audette, W. E.; Barton, M. D.; Hilderbrand, J. K.; Marshall, W. S.; Rey, C. M.; Winter, D. S.; Petro, A. J.

    2008-03-01

    The development and testing of a flow cooling system for high-temperature superconducting (HTS) magnets is described. The system includes a turbo-Brayton cryocooler, a magnet thermal interface, and a magnet thermal isolation and support system. The target application is the Variable Specific Impulse Magnetoplasma Rocket (VASIMR). Turbo-Brayton coolers are well suited to such spacecraft applications, as they are compact, modular, lightweight, and efficient, with long maintenance-free lifetimes. Furthermore, the technology scales well to high-cooling capacities. The feasibility of using turbo-Brayton coolers in this application was proven in a design exercise in which existing cooler designs were scaled to provide cooling for the magnet sets required by 200 kW and 1 MW VASIMR engines. The performance of the concepts for the thermal interface and the thermal isolation and support system were measured in separate laboratory tests with a demonstration system built about a representative HTS magnet. Cooling for these tests was provided by a flow cooling loop comprising a compressor, recuperator and GM cryocooler, with the flow pressure, temperature, and mass flow rate selected to effectively simulate the turbo-Brayton operating condition. During system testing, the magnet was cooled below its design operating temperature of 35 K, and good thermal uniformity (<0.4 K) and low thermal loads (<0.5 W) were demonstrated.

  13. Advances in high power semiconductor diode lasers

    Science.gov (United States)

    Ma, Xiaoyu; Zhong, Li

    2008-03-01

    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  14. Control grid motion estimation for efficient application of optical flow

    CERN Document Server

    Zwart, Christine M

    2012-01-01

    Motion estimation is a long-standing cornerstone of image and video processing. Most notably, motion estimation serves as the foundation for many of today's ubiquitous video coding standards including H.264. Motion estimators also play key roles in countless other applications that serve the consumer, industrial, biomedical, and military sectors. Of the many available motion estimation techniques, optical flow is widely regarded as most flexible. The flexibility offered by optical flow is particularly useful for complex registration and interpolation problems, but comes at a considerable compu

  15. Monitoring of multiphase flows for superconducting accelerators and others applications

    Science.gov (United States)

    Filippov, Yu. P.; Kakorin, I. D.; Kovrizhnykh, A. M.; Miklayev, V. M.

    2017-07-01

    This paper is a review on implementation of measuring systems for two-phase helium, hydrogen, liquefied natural gas (LNG), and oil-formation/salty water flows. Two types of such systems are presented. The first type is based on two-phase flow-meters combining void fraction radio-frequency (RF) sensors and narrowing devices. They can be applied for superconducting accelerators cooled with two-phase helium, refueling hydrogen system for space ships and some applications in oil production industry. The second one is based on combination of a gamma-densitometer and a narrowing device. These systems can be used to monitor large two-phase LNG and oil-formation water flows. An electronics system based on a modular industrial computer is described as well. The metrological characteristics for different flow-meters are presented and the obtained results are discussed. It is also shown that the experience gained allows separationless flow-meter for three-phase oil-gas-formation water flows to be produced.

  16. Investigation of Current-Voltage Characteristics of Ni/GaN Schottky Barrier Diodes for Potential HEMT Applications

    Directory of Open Access Journals (Sweden)

    Ashish Kumar

    2011-01-01

    Full Text Available In the present work, the I-V characteristics of Ni/GaN Schottky diodes have been studied. The Schottky diodes, having different sizes using Ni/Au and ohmic contacts using Ti/Al/Ni/Au were made on n-GaN. The GaN was epitaxially grown on c-plane sapphire by metal organic chemical vapor deposition (MOCVD technique and had a thickness of about 3.7 µm. The calculated ideality factor and barrier height from current-voltage (I-V characteristics (at 300 K for two GaN Schottky diodes were close to ~1.3 and ~ 0.8 eV respectively. A high reverse leakage current in the order of 10 – 4A/cm2 (at – 1 V was observed in both diodes. A careful analysis of forward bias I-V characteristics showed very high series resistance and calculation for ideality factor indicated presence of other current transport mechanism apart from thermionic model at room temperature.

  17. Mechanism of Fast Current Interruption in p -π -n Diodes for Nanosecond Opening Switches in High-Voltage-Pulse Applications

    Science.gov (United States)

    Sharabani, Y.; Rosenwaks, Y.; Eger, D.

    2015-07-01

    Step-recovery diodes operating in the snappy recovery regime are used as opening switches for generating narrow pulses with high-voltage amplitude. Physical modeling of the switching process is complex due to the large number of parameters involved, including diode structure, the extreme physical conditions, and the effect of external driving conditions. In this work, we address the problem by using a physical device simulator for solving the coupled device and electrical driving circuit equations. This method allows deciphering of the physical processes to take place in the diode during the fast current interruption phase. Herein we analyze the complete hard (snappy) reverse recovery process in short-base devices and determine the fast-transition-phase mechanism. It was found that the fast current interruption phase is constructed of two processes; the main parameters governing the switching time duration and the prepulse magnitude are the diode's reverse current density and its base-doping concentration. We describe the dependence of the switching performance in these parameters.

  18. Micro-segmented flow applications in chemistry and biology

    CERN Document Server

    Cahill, Brian

    2014-01-01

    The book is dedicated to the method and application potential of micro segmented flow. The recent state of development of this powerful technique is presented in 12 chapters by leading researchers from different countries. In the first section, the principles of generation and manipulation of micro-fluidic segments are explained. In the second section, the micro continuous-flow synthesis of different types of nanomaterials is shown as a typical example for the use of advantages of the technique in chemistry. In the third part, the particular importance of the technique in biotechnical applications is presented demonstrating the progress for miniaturized cell-free processes, for molecular biology and DNA-based diagnostis and sequencing as well as for the development of antibiotics and the evaluation of toxic effects in medicine and environment.

  19. Flow, transport and diffusion in random geometries II: applications

    KAUST Repository

    Asinari, Pietro

    2015-01-07

    Multilevel Monte Carlo (MLMC) is an efficient and flexible solution for the propagation of uncertainties in complex models, where an explicit parametrization of the input randomness is not available or too expensive. We present several applications of our MLMC algorithm for flow, transport and diffusion in random heterogeneous materials. The absolute permeability and effective diffusivity (or formation factor) of micro-scale porous media samples are computed and the uncertainty related to the sampling procedures is studied. The algorithm is then extended to the transport problems and multiphase flows for the estimation of dispersion and relative permeability curves. The impact of water drops on random stuctured surfaces, with microfluidics applications to self-cleaning materials, is also studied and simulated. Finally the estimation of new drag correlation laws for poly-dispersed dilute and dense suspensions is presented.

  20. Flow visualization using momentum and energy transport tubes and applications to turbulent flow in wind farms

    CERN Document Server

    Meyers, Johan

    2012-01-01

    As a generalization of the mass-flux based classical stream-tube, the concept of momentum and energy transport tubes is discussed as a flow visualization tool. These transport tubes have the property, respectively, that no fluxes of momentum or energy exist over their respective tube mantles. As an example application using data from large-eddy simulation, such tubes are visualized for the mean-flow structure of turbulent flow in large wind farms, in fully developed wind-turbine-array boundary layers. The three-dimensional organization of energy transport tubes changes considerably when turbine spacings are varied, enabling the visualization of the path taken by the kinetic energy flux that is ultimately available at any given turbine within the array.

  1. OPTIMIZATION AND APPLICATIONS OF REVERSE-FLOW CYCLONES

    Institute of Scientific and Technical Information of China (English)

    Guogang Sun; Jianyi Chen; Mingxian Shi

    2005-01-01

    An optimum design approach to reverse-flow cyclones based on the concept of optimizing cyclone dimensions is introduced in this paper. This approach involves optimizing cyclone dimensions by categories, calculating cyclone performance by correlating similitude numbers and optimizing the combination of four cyclone parameters, D, KA,(-d- and vi, which has been proven to be applicable not only for single-stage cyclone, but also for multistage cyclone separators. Applications of the designed cyclones in FCC units and acrylonitrile reactors are also presented.

  2. Self-flowing mortar for ferrocement in strengthening applications

    Directory of Open Access Journals (Sweden)

    Shamir Sakir

    2016-09-01

    Full Text Available Ferrocement technology is becoming more and more important nowadays for strengthening and retrofitting of concrete structures mainly due to its inherent strength properties. However, its labour intensive nature makes it undesirable for rapid strengthening works. In narrow spaces, strengthening with conventional ferrocement is very critical and also time consuming. Self-flowing mortar (SFM could be used with this technology to overcome these limitations. This article discusses the applicability of SFM in ferrocement technology. The aim of this study is to summarize available knowledge on SFM to make it feasible for optimization in different industrial applications.

  3. Viscous flow modelling using unstructured meshes for aeronautical applications

    Science.gov (United States)

    Szmelter, J.; Pagano, A.

    The novel application of viscous coupling to unstructured meshes has been proposed and developed. The method allows fro viscous flows modelling and avoids the difficulty of generating highly stretched tetrahedral in 3D or triangular in 2D elements required for Navier-Stokes solvers. The time step allowed by the explicit euler solver is limited by the size of the "Euler" mesh, resulting in faster algorithms than standard explicit Navier-Stokes solvers.

  4. Turbulence introduction to theory and applications of turbulent flows

    CERN Document Server

    Westerweel, Jerry; Nieuwstadt, Frans T M

    2016-01-01

    This book provides a general introduction to the topic of turbulent flows. Apart from classical topics in turbulence, attention is also paid to modern topics. After studying this work, the reader will have the basic knowledge to follow current topics on turbulence in scientific literature. The theory is illustrated with a number of examples of applications, such as closure models, numerical simulations and turbulent diffusion, and experimental findings. The work also contains a number of illustrative exercises.

  5. Materials for diode pumped solid state lasers

    Science.gov (United States)

    Chase, L. L.; Davis, L. E.; Krupke, W. F.; Payne, S. A.

    1991-07-01

    The advantages of semiconductor diode lasers and laser arrays as pump sources for solid state lasers are reviewed. The properties that are desirable in solid state laser media for various diode pumping applications are discussed, and the characteristics of several promising media are summarized.

  6. New and classical applications of heat flow studies

    Science.gov (United States)

    Clauser, C.

    2005-12-01

    This special issue of Journal of Geophysics and Engineering is dedicated to a collection of papers which resulted from an international workshop held in Aachen, Germany, on 4-7 October 2004, called 'New and Classical Applications of Heat Flow Studies'. This was the third in a series of topical geothermal workshops arranged by the Geothermal Working Group of the German Geophysical Society (DGG) and was organized by the Institute of Applied Geophysics at RWTH Aachen University under the auspices of the International Heat Flow Commission of the International Association of Seismology and Physics (IASPEI). The meeting was attended by some 60 scientists from 14 countries and three continents. Financial assistance, granted by DGG and IASPEI, allowed us to provide partial support for a total of eight students, young scientists and eminent researchers from eastern Europe and overseas. The convenors of the meeting were Christoph Clauser (Aachen), Thomas Kohl (Zürich) and Makoto Taniguchi (Kyoto). The main local organizers were Volker Rath (scientific programme) and Ute Kreutz (accommodation and financial affairs). The topics addressed in more than 50 oral and poster presentations indicated that today intriguing new applications of heat flow studies have emerged, complementing the classical topics of heat flow mapping and the tectonic implications of heat flow. In classical applications, for instance, thermal signatures of water flow or downward diffusion of variations in the Earth's mean temperature are considered as noise which needs to be corrected prior to further use of the data. In contrast, in several new applications it is exactly the information contained in these signatures which has been extracted and interpreted. For instance, over the past two decades, work on the most prominent of these new applications has been devoted to inverting the variation of the Earth's past mean ground surface temperature (GST). As of today, GST provided by the geothermal method has

  7. Direct Determination of Harmonic and Inter-modulation distortions with an application to Single Mode Laser Diodes

    CERN Document Server

    Tannous, C

    2001-01-01

    Harmonic and Intermodulation distortions occur when a physical system is excited with a single or several frequencies and when the relationship between the input and output is non-linear. Working with non-linearities in the Frequency domain is not straightforward specially when the relationship between the input and output is not trivial. We outline the complete derivation of the Harmonic and Intermodulation distortions from basic principles to a general physical system. For illustration, the procedure is applied to the Single Mode laser diode where the relationship of input to output is non-trivial. The distortions terms are extracted directly from the Laser Diode rate equations and the method is tested by comparison to many results cited in the literature. This methodology is general enough to be applied to the extraction of distortion terms to any desired order in many physical systems in a general and systematic way.

  8. Red Blood Cell Forms in Acne and their Complex Treatment with Application of Light-Emitting Diode Influences

    Directory of Open Access Journals (Sweden)

    Farhad F. Khashimov

    2014-12-01

    Full Text Available The efficiency of the laser light-emitting diode (LED that is used in the complex treatment of acne was studied with light microscopy, scanning electron microscopy, and planimetry. It was found that the light emission of the photon matrix by A.Korobov–B.Korobov “Barva-Fleks/BIR” (λ1=470nm and λ2=940 nm combined with the drug treatment are an effective means for the treatment of acne.

  9. Topological Fluid Mechanics with Applications to Free Surfaces and Axisymmetric Flows

    DEFF Research Database (Denmark)

    Brøns, Morten

    1996-01-01

    Topological fluid mechanics is the study of qualitative features of fluid patterns. We discuss applications to the flow beneath a stagnant surface film, and to patterns in axisymmetric flow.......Topological fluid mechanics is the study of qualitative features of fluid patterns. We discuss applications to the flow beneath a stagnant surface film, and to patterns in axisymmetric flow....

  10. Photoluminescence performance enhancement of ZnO/MgO heterostructured nanowires and their applications in ultraviolet laser diodes.

    Science.gov (United States)

    Shi, Zhi-Feng; Zhang, Yuan-Tao; Cui, Xi-Jun; Zhuang, Shi-Wei; Wu, Bin; Chu, Xian-Wei; Dong, Xin; Zhang, Bao-Lin; Du, Guo-Tong

    2015-06-07

    Vertically aligned ZnO/MgO coaxial nanowire (NW) arrays were prepared on sapphire substrates by metal-organic chemical vapor deposition combined with a sputtering system. We present a comparative investigation of the morphological and optical properties of the produced heterostructures with different MgO layer thicknesses. Photoluminescence measurements showed that the optical performances of ZnO/MgO coaxial NWs were strongly dependent on the MgO layer thickness. The intensity of deep-level emission (DLE) decreased monotonously with the increase of MgO thickness, while the enhancement of ultraviolet (UV) emission showed a critical thickness of 15 nm, achieving a maximum intensity ratio (∼226) of IUV/IDLE at the same time. The significantly improved exciton emission efficiency of the coaxial NW structures allows us to study the surface passivation effect, photogenerated carrier confinement and transfer in terms of energy band theory. More importantly, we achieved an ultralow threshold (4.5 mA, 0.58 A cm(-2)) electrically driven UV lasing action based on the ZnO/MgO NW structures by constructing an Au/MgO/ZnO metal/insulator/semiconductor diode, and the continuous-current-driven diode shows a good temperature tolerance. The results obtained on the unique optical properties of ZnO/MgO coaxial NWs shed light on the design and development of ZnO-based UV laser diodes assembled with nanoscale building blocks.

  11. Dimensional characteristics of welds performed on AISI 1045 steel by means of the application of high power diode laser; Caracteristicas dimensionales de soldadura formadas sobre el acero AISI 1045 mediante la aplicacion del laser diodo de alta potencia

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Castillo, A.; Pou, J.; Lusquinos, F.; Quintero, F.; Soto, R.; Boutinguiza, M.; Saavedra, M.; Perez-Amor, M.

    2004-07-01

    The named High Power diode Laser (HPDL), emits a beam of optical energy generated by diode stimulation and offers the capability of supplying levels of power up to 6 kW. The objective of this research work was to study the main welding variables and their effects on dimensional characteristics of the beads performed by means of application of this novel laser. The results obtained, show that HPDL, is an energy source able to perform welds on AISI 1045 steel plates under conduction mode, without any kind of mechanized preparation, preheating or post-weld treatment and, without filler metal application. (Author) 16 refs.

  12. Graphene field-effect transistor application for flow sensing

    Directory of Open Access Journals (Sweden)

    Łuszczek Maciej

    2017-01-01

    Full Text Available Microflow sensors offer great potential for applications in microfluidics and lab-on-a-chip systems. However, thermal-based sensors, which are commonly used in modern flow sensing technology, are mainly made of materials with positive temperature coefficients (PTC and suffer from a self-heating effect and slow response time. Therefore, the design of novel devices and careful selection of materials are required to improve the overall flow sensor performance. In this work we propose graphene field-effect transistor (GFET to be used as microflow sensor. Temperature distribution in graphene channel was simulated and the analysis of heat convection was performed to establish the relation between the fluidic flow velocity and the temperature gradient. It was shown that the negative temperature coefficient (NTC of graphene could enable the self-protection of the device and should minimize sensing error from currentinduced heating. It was also argued that the planar design of the GFET sensor makes it suitable for the real application due to supposed mechanical stability of such a construction.

  13. Graphene field-effect transistor application for flow sensing

    Science.gov (United States)

    Łuszczek, Maciej; Świsulski, Dariusz; Hanus, Robert; Zych, Marcin; Petryka, Leszek

    Microflow sensors offer great potential for applications in microfluidics and lab-on-a-chip systems. However, thermal-based sensors, which are commonly used in modern flow sensing technology, are mainly made of materials with positive temperature coefficients (PTC) and suffer from a self-heating effect and slow response time. Therefore, the design of novel devices and careful selection of materials are required to improve the overall flow sensor performance. In this work we propose graphene field-effect transistor (GFET) to be used as microflow sensor. Temperature distribution in graphene channel was simulated and the analysis of heat convection was performed to establish the relation between the fluidic flow velocity and the temperature gradient. It was shown that the negative temperature coefficient (NTC) of graphene could enable the self-protection of the device and should minimize sensing error from currentinduced heating. It was also argued that the planar design of the GFET sensor makes it suitable for the real application due to supposed mechanical stability of such a construction.

  14. SIFT flow: dense correspondence across scenes and its applications.

    Science.gov (United States)

    Liu, Ce; Yuen, Jenny; Torralba, Antonio

    2011-05-01

    While image alignment has been studied in different areas of computer vision for decades, aligning images depicting different scenes remains a challenging problem. Analogous to optical flow, where an image is aligned to its temporally adjacent frame, we propose SIFT flow, a method to align an image to its nearest neighbors in a large image corpus containing a variety of scenes. The SIFT flow algorithm consists of matching densely sampled, pixelwise SIFT features between two images while preserving spatial discontinuities. The SIFT features allow robust matching across different scene/object appearances, whereas the discontinuity-preserving spatial model allows matching of objects located at different parts of the scene. Experiments show that the proposed approach robustly aligns complex scene pairs containing significant spatial differences. Based on SIFT flow, we propose an alignment-based large database framework for image analysis and synthesis, where image information is transferred from the nearest neighbors to a query image according to the dense scene correspondence. This framework is demonstrated through concrete applications such as motion field prediction from a single image, motion synthesis via object transfer, satellite image registration, and face recognition.

  15. Efficient second harmonics generation of a laser-diode-pumped Nd:YAG laser and its applications. Laser diode reiki Nd:YAG laser no kokoritsu daini kochoha hassei to sono oyo

    Energy Technology Data Exchange (ETDEWEB)

    Kubota, S.; Oka, M. (Sony Corp., Tokyo (Japan))

    1991-08-10

    Stabilization of the second harmonics in a laser-diode-pumped Nd:YAG laser and its application are described. The laser is a quantum noise limiting laser, in which a mode competing noise is generated from an interaction between the laser medium Nd:YAG and the type II nonlinear optical crystal KTiOPO{sub 4} when generating a second harmonics in the resonator. However, the quantum noise limiting second harmonics was obtained by means of inserting (1/4) wave length plate in the resonator to release the bond between two intersecting inherent polarization modes. This stabilized green laser is of a single lateral mode is nearly free of aberration. Therefore, an optical disc prototype having three times as much of the currently used density was made using an objective lens having high number of openings to collect lights, which was verified capable of regeneration at a high signal to noise ratio. In addition, higher output is possible by means of parallelizing the excitation, and high output is realized from edge excitation at a fiber bundle. 18 refs., 3 figs.

  16. Principles and Applications of Flow Injection Analysis in Biosensors

    DEFF Research Database (Denmark)

    Hansen, Elo Harald

    1996-01-01

    In practical applications biosensors are often forced to operate under less than optimal conditions. Because of their construction, and the physical processes and chemical reactions involved in their operation, compromise conditions are frequently required to synchronize all events taking place....... Therefore, and in order to implement functions such as periodic calibration, conditioning and possible regeneration of the biosensor, and, very importantly, to yield the freedom to select the optimum detection means, it is advantageous to use these devices in a flow-through mode, particularly by employing...... the flow injection (FI) approach. The capacity of FI, as offering itself as a complementary facility to augment the performance of biosensors, and in many cases as an attractive alternative, is demonstrated by reference to selected examples, comprising assays based on enzymatic procedures with optical...

  17. Discontinuous Galerkin method analysis and applications to compressible flow

    CERN Document Server

    Dolejší, Vít

    2015-01-01

    The subject of the book is the mathematical theory of the discontinuous Galerkin method (DGM), which is a relatively new technique for the numerical solution of partial differential equations. The book is concerned with the DGM developed for elliptic and parabolic equations and its applications to the numerical simulation of compressible flow. It deals with the theoretical as well as practical aspects of the DGM and treats the basic concepts and ideas of the DGM, as well as the latest significant findings and achievements in this area. The main benefit for readers and the book’s uniqueness lie in the fact that it is sufficiently detailed, extensive and mathematically precise, while at the same time providing a comprehensible guide through a wide spectrum of discontinuous Galerkin techniques and a survey of the latest efficient, accurate and robust discontinuous Galerkin schemes for the solution of compressible flow.

  18. Bulk flow and diffusion revisited, and clinical applications.

    Science.gov (United States)

    Reulen, Hans-J

    2010-01-01

    The first Klatzo-Lecture pays homage to an exceptional academician, scientist and teacher. The author spent nearly 1 year in Klatzo's laboratory at the NHI in Bethesda, and the first part of results presented here originate directly from this collaboration. It was shown that following cortical injury, movement of edema fluid into the tissue occurs by bulk flow, and that the driving force is a small tissue pressure gradient. Resolution of edema fluid is achieved by clearance into the ventricular and subarachnoid CSF, is enhanced in the presence of pressure gradients and is supported by re-absorption into capillaries. Using appropriate techniques, the formation rate as well as clearance of edema into CSF and tissue resorption could be determined in human brain metastases and malignant gliomas. Three examples of clinical applications based on the discussed mechanisms are presented: a. Fluorescence-guided surgery of gliomas is based on the accumulation of 5-ALA in tumour cells; there being enzymatically converted to PP-IX, a compound with deep red fluorescence. This fluorescence is used for the more accurate surgical removal of gliomas. b. Radioimmunotherapy of gliomas uses an anti-tenascin antibody, coupled with a nuclide, administered postoperatively into the tumour cavity, from where it diffuses into tissue, couples to the receptor at the glioma cells. Then the isotope destroys the tumour cells. c. Convection-enhanced delivery is based on the interstitial infusion of an appropriate cytotoxic drug into the white matter at low pressure. Thus, the method employs bulk flow, distributes a drug in a larger tissue volume and eventually achieves drug concentrations greater than systemic levels. Experimental studies and clinical results are presented for all three clinical applications.I am very grateful to Z. Czernicki and the organizing group for being offered the great honour of presenting the first Igor Klatzo Lecture. In this report first previous results of bulk flow

  19. Fabrication and Characterization of Planar Dipole Antenna Integrated with GaAs Based-Schottky Diode for On-chip Electronic Device Application

    Energy Technology Data Exchange (ETDEWEB)

    Mustafa, Farahiyah; Hashim, Abdul Manaf; Parimon, Norfarariyanti; Rahman, Shaharin Fadzli Abd; Rahman, Abdul Rahim Abdul [Material Innovations and Nanoelectronics Research Group, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Osman, Mohd Nizam [Telekom Research and Development, TM Innovation Centre, 63000 Cyberjaya (Malaysia); Aziz, Azlan Abdul; Hashim, Md Roslan, E-mail: manaf@fke.utm.my [Nano-Optoelectronics Research, Faculty of Physics, Universiti Sains Malaysia, 11800 Minden, Penang (Malaysia)

    2011-02-15

    The design and RF characteristics of planar dipole antennas facilitated with coplanar waveguide (CPW) structure on semi-insulated GaAs are performed and confirmed to work in super high frequency (SHF) range. As expected, the fundamental resonant frequency shifts to higher frequency when the length of antenna decreases. Interestingly, the resonant frequencies of antenna are almost unchanged with the variation of antenna width and metal thickness. It is shown experimentally that return loss down to -54 dB with a metal thickness of 50 nm is obtainable. Preliminary investigation on design, fabrication, and DC and RF characteristics of the integrated device (planar dipole antenna + Schottky diode) on AlGaAs/GaAs HEMT structure is presented. From the preliminary direct irradiation experiments using the integrated device, the Schottky diode is not turned on due to weak reception of RF signal by dipole antenna. Further extensive considerations on the polarization of irradiation etc. need to be carried out in order to improve the signal reception. These preliminary results provide a new breakthrough for on-chip electronic device application in nanosystems.

  20. Photometric flow injection determination of phosphate on a PDMS microchip using an optical detection system assembled with an organic light emitting diode and an organic photodiode.

    Science.gov (United States)

    Liu, Rong; Ishimatsu, Ryoichi; Yahiro, Masayuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko

    2015-01-01

    A compact photometric detector was constructed from an organic light emitting diode (OLED) based on a europium complex, europium(diben-zoylmethanato)3(bathophenanthroline) (Eu(DBM)3bath), as the light source and an organic photodiode (OPD) fabricated from a hetero-junction of two layers of copper phthalocyanine (CuPc)/fullerene (C60) as the photo-detector on a microchip prepared from poly(dimethylsiloxan) (PDMS) and was applied to the determination of phosphate. The OLED and the OPD were fabricated by a vapor deposition method on an indium tin oxide (ITO) coated glass substrate with the following layered structure; Glass (0.7 mm)/ITO (110 nm)/4,4'-bis[N-(1-naphthyl)-N-phenyl amino]-biphenyl (α-NPD) (30 nm)/4,4'-di(N-carbazolyl)biphenyl (CBP): Eu(3+) (8 wt%, 30 nm)/bathocuproine (BCP) (30 nm)/aluminum tris(8-hydroxyquinoline) (Alq3) (25 nm)/magnesium and silver (MgAg) (100 nm)/Ag (10nm) and Glass (0.7 mm)/ITO (110 nm)/CuPc (35 nm)/C60 (50 nm)/BCP (10 nm)/Ag (50 nm), respectively. The OLED based on the europium complex emitted a sharp light at the wavelength of 612 nm with a full width at half maximum (FWHM) of 8 nm. The performance of the photometric detector assembled was evaluated based on measurements of the absorbance of different concentrations of malachite green (MG) solutions for a batch system with 1cm long path length. The molar absorptive coefficient of the MG solution, calculated from the photocurrent of the OPD, was in good agreement with the value reported in the literature. A microchip with two inlets and one outlet U-shaped channel was prepared by a conventional photolithograph method. The OLED and the OPD were configured so as to face each other through the PDMS microchip in parallel in order to align the light axis of the OLED and the OPD with the flow cell (optical path length of 5mm), which was located at the end of outlet. For the determination of phosphate, an ion-association reaction between MG and a molybdenum-phosphate complex was utilized

  1. Novel Single-Frequency Diode Pumped Solid-State Lasers and Their Applications in Laser Ranging and Velocimetry

    Institute of Scientific and Technical Information of China (English)

    杨苏辉; 吴克瑛; 魏光辉

    2001-01-01

    Two models of laser diode pumped unidirectional single-frequency ring lasers with maximum single-frequency output powers of 1 W and 780mW are investigated. The statistical linewidth of the free-run laser is measured to be 2.1 kHz within 5μs by using a single-mode fibre link. We use the monolithic laser to measure the angular speed of a spinning motor and simulate a linearly frequency modulated continuous-wave ladar system in the laboratory.

  2. Bridging Inter-flow and Intra-flow Network Coding for Video Applications

    DEFF Research Database (Denmark)

    Hansen, Jonas; Krigslund, Jeppe; Roetter, Daniel Enrique Lucani;

    2013-01-01

    transmission approach to decide how much and when to send redundancy in the network, and a minimalistic feedback mechanism to guarantee delivery of generations of the different flows. Given the delay constraints of video applications, we proposed a simple yet effective coding mechanism, Block Coding On The Fly...... (BCFly), that allows a block encoder to be fed on-the-fly, thus reducing the delay to accumulate enough packets that is introduced by typical generation based NC techniques. Our measurements and comparison to forwarding and COPE show that CORE not only outperforms these schemes even for small packet...

  3. Application of Stochastic Fracture Network with Numerical Fluid Flow Simulations to Groundwater Flow Modeling in Fractured Rocks

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The continuum approach in fluid flow modeling is generally applied to porous geological media,but has limitel applicability to fractured rocks. With the presence of a discrete fracture network relatively sparsely distributed in the matrix, it may be difficult or erroneous to use a porous medium fluid flow model with continuum assumptions to describe the fluid flow in fractured rocks at small or even large field scales. A discrete fracture fluid flow approach incorporating a stochastic fracture network with numerical fluid flow simulations could have the capability of capturing fluid flow behaviors such as inhomogeneity and anisotropy while reflecting the changes of hydraulic features at different scales.Moreover, this approach can be implemented to estimate the size of the representative elementary volume (REV) in order to find out the scales at which a porous medium flow model could be applied, and then to determine the hydraulic conductivity tensor for fractured rocks. The following topics are focused on in this study: (a) conceptual discrete fracture fluid flow modeling incorporating a stochastic fracture network with numerical flow simulations; (b) estimation of REVand hydraulic conductivity tensor for fractured rocks utilizing a stochastic fracture network with numerical fluid flow simulations; (c) investigation of the effect of fracture orientation and density on the hydraulic conductivity and REV by implementing a stochastic fracture network with numerical fluid flow simulations, and (d) fluid flow conceptual models accounting for major and minor fractures in the 2-D or 3-D flow fields incorporating a stochastic fracture network with numerical fluid flow simulations.``

  4. On Mixed Flow Turbines for Automotive Turbocharger Applications

    Directory of Open Access Journals (Sweden)

    Bernhardt Lüddecke

    2012-01-01

    Full Text Available Due to increased demands for improved fuel economy of passenger cars, low-end and part-load performance is of key importance for the design of automotive turbocharger turbines. In an automotive drive cycle, a turbine which can extract more energy at high pressure ratios and lower rotational speeds is desirable. In the literature it is typically found that radial turbines provide peak efficiency at speed ratios of 0.7, but at high pressure ratios and low rotational speeds the blade speed ratio will be low and the rotor will experience high values of positive incidence at the inlet. Based on fundamental considerations, it is shown that mixed flow turbines offer substantial advantages for such applications. Moreover, to prove these considerations an experimental assessment of mixed flow turbine efficiency and optimal blade speed ratio is presented. This has been achieved using a new semi-unsteady measurement approach. Finally, evidence of the benefits of mixed flow turbine behaviour in engine operation is given. Regarding turbocharged engine simulation, the benefit of wide-ranging turbine map measurement data as well as the need for reasonable turbine map extrapolation is illustrated.

  5. Systematic study of GeSn heterostructure-based light-emitting diodes towards mid-infrared applications

    Science.gov (United States)

    Zhou, Yiyin; Dou, Wei; Du, Wei; Pham, Thach; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Mosleh, Aboozar; Alher, Murtadha; Margetis, Joe; Tolle, John; Sun, Greg; Soref, Richard; Li, Baohua; Mortazavi, Mansour; Naseem, Hameed; Yu, Shui-Qing

    2016-07-01

    Temperature-dependent characteristics of GeSn light-emitting diodes with Sn composition up to 9.2% have been systematically studied. Such diodes were based on Ge/GeSn/Ge double heterostructures (DHS) that were grown directly on a Si substrate via a chemical vapor deposition system. Both photoluminescence and electroluminescence spectra have been characterized at temperatures from 300 to 77 K. Based on our theoretical calculation, all GeSn alloys in this study are indirect bandgap materials. However, due to the small energy separation between direct and indirect bandgap, and the fact that radiative recombination rate greater than non-radiative, the emissions are mainly from the direct Γ-valley to valence band transitions. The electroluminescence emissions under current injection levels from 102 to 357 A/cm2 were investigated at 300 K. The monotonic increase of the integrated electroluminescence intensity was observed for each sample. Moreover, the electronic band structures of the DHS were discussed. Despite the indirect GeSn bandgap owing to the compressive strain, type-I band alignment was achieved with the barrier heights ranging from 11 to 47 meV.

  6. Unsteady airfoil flows with application to aeroelastic stability

    Energy Technology Data Exchange (ETDEWEB)

    Johansen, Jeppe

    1999-09-01

    The present report describes numerical investigation of two-dimensional unsteady airfoil flows with application to aeroelastic stability. The report is divided in two parts. Part A describes the purely aerodynamic part, while Part B includes the aeroelastic part. In Part A a transition prediction algorithm based on a simplified version of the e{sup n} method is proposed. Laminar Boundary Layer instability data are stored in a database from which stability characteristics can be extracted by interpolation. Input to the database are laminar integral boundary layer parameters. These are computed from an integral boundary layer formulation coupled to a Navier-Stokes flow solver. Five different airfoils are considered at fixed angle of attack, and the flow is computed assuming both fully turbulent and transitional flow and compared with experimental data. Results indicate that using a transition model the drag prediction is improved considerably. Also the lift is slightly improved. At high angles of attack transition will affect leading edge separation which again will affect the overall vortex shedding. If the transition point is not properly predicted this will affect the whole hysteresis curve. The transition model developed in the present work showed more stable predictions compared to the empirical transition model. In Part B a simple three degrees-of-freedom (DOF) structural dynamics model is developed and coupled to the aerodynamics models from Part A. A 2nd order accurate time integration scheme is used to solve the equations of motion. Two airfoils are investigated. The aeroelastic models predict stable conditions well at low angle of attack. But at high angles of attack, and where unstable behaviour is expected, only the Navier-Stokes solver predict correct aeroelastic response. The semi-empirical dynamic stall model does not predict vortex shedding and moment correctly leading to an erroneous aerodynamic damping. (au) 5 tabs.; 55 ills., 52 refs.

  7. Infrared tunable diode laser applications: (i) atmospheric pollutants monitoring (ii) gas phase kinetics of elementary reactions; Application des diodes laser infrarouge accordables a deux problematiques: (i) la metrologie de polluants (ii) la cinetique des reactions elementaires

    Energy Technology Data Exchange (ETDEWEB)

    Dusanter, S.

    2002-12-15

    Infrared Tunable Diode Laser Absorption Spectroscopy provides sensibility, selectivity and high temporal resolution. We have applied this technique to atmospheric trace pollutants monitoring and to gas phase kinetics of elementary reactions. For metrology, we have developed a novel and effective protocol: pressure increase measurements. It has been applied to monitoring nitrous oxide, formaldehyde, acetaldehyde and 1,3-butadiene, in air or car exhausts. This work represents a first step toward the elaboration of a compact and portable instrument. The kinetic setup, where reactions are initiated by laser photolysis, has been validated with the well-known reactions of formyl and hydroxymethyl radicals with oxygen. A preliminary study of the rate constant for the unimolecular decomposition of pivaloyl radical has been performed. (author)

  8. Preparation and characterization of electrodeposited ZnO and ZnO:Co nanorod films for heterojunction diode applications

    Energy Technology Data Exchange (ETDEWEB)

    Caglar, Yasemin, E-mail: yasemincaglar@anadolu.edu.tr [Anadolu University, Science Faculty, Physics Department, Eskisehir (Turkey); Arslan, Andaç [Eskisehir Osmangazi University, Art and Science Faculty, Chemistry Department, Eskisehir (Turkey); Ilican, Saliha [Anadolu University, Science Faculty, Physics Department, Eskisehir (Turkey); Hür, Evrim [Eskisehir Osmangazi University, Art and Science Faculty, Chemistry Department, Eskisehir (Turkey); Aksoy, Seval; Caglar, Mujdat [Anadolu University, Science Faculty, Physics Department, Eskisehir (Turkey)

    2013-10-15

    was affected significantly by Co content. The pn heterojunction diodes were fabricated and the diode parameters were determined from the analysis of the measured dark current–voltage curves. Rectifying behavior was observed from the I–V characteristics of these heterojunction diodes.

  9. Coaxial foilless diode

    OpenAIRE

    Long Kong; QingXiang Liu; XiangQiang Li; ShaoMeng Wang

    2014-01-01

    A kind of coaxial foilless diode is proposed in this paper, with the structure model and operating principle of the diode are given. The current-voltage relation of the coaxial foilless diode and the effects of structure parameters on the relation are studied by simulation. By solving the electron motion equation, the beam deviation characteristic in the presence of external magnetic field in transmission process is analyzed, and the relationship between transverse misalignment with diode par...

  10. Coaxial foilless diode

    OpenAIRE

    Long Kong; QingXiang Liu; XiangQiang Li; ShaoMeng Wang

    2014-01-01

    A kind of coaxial foilless diode is proposed in this paper, with the structure model and operating principle of the diode are given. The current-voltage relation of the coaxial foilless diode and the effects of structure parameters on the relation are studied by simulation. By solving the electron motion equation, the beam deviation characteristic in the presence of external magnetic field in transmission process is analyzed, and the relationship between transverse misalignment with diode par...

  11. Header For Laser Diode

    Science.gov (United States)

    Rall, Jonathan A. R.; Spadin, Paul L.

    1990-01-01

    Header designed to contain laser diode. Output combined incoherently with outputs of other laser diodes in grating laser-beam combiner in optical communication system. Provides electrical connections to laser diode, cooling to thermally stabilize laser operation, and optomechanical adjustments that steer and focus laser beam. Range of adjustments provides for correction of worst-case decentering and defocusing of laser beam encountered with laser diodes. Mechanical configuration made simple to promote stability and keep cost low.

  12. Selection of the optimal combination of water vapor absorption lines for detection of temperature in combustion zones of mixing supersonic gas flows by diode laser absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mironenko V.R.

    2017-01-01

    Full Text Available Determination of a gas medium temperature by diode laser absorption spectrometry (DLAS is based on the measurement of integral intensities of the absorption lines of a test molecule (generally water vapor molecule. In case of local thermodynamic equilibrium temperature is inferred from the ratio of the integral intensities of two lines with different low energy levels. For the total gas pressure above 1 atm the absorption lines are broadened and one cannot find isolated well resolved water vapor absorption lines within relatively narrow spectral interval of fast diode laser (DL tuning range (about 3 cm−1. For diagnostics of a gas object in the case of high temperature and pressure DLAS technique can be realized with two diode lasers working in different spectral regions with strong absorption lines. In such situation the criteria of the optimal line selection differs significantly from the case of narrow lines. These criteria are discussed in our work. The software for selection the optimal spectral regions using the HITRAN-2012 and HITEMP data bases is developed. The program selects spectral regions of DL tuning, minimizing the error of temperature determination δТ/T, basing on the attainable experimental error of line intensity measurement δS. Two combinations of optimal spectral regions were selected – (1.392 & 1.343 μm and (1.392 & 1.339 μm. Different algorithms of experimental data processing are discussed.

  13. Application of flow field-flow fractionation for the characterization of macromolecules of biological interest: a review

    NARCIS (Netherlands)

    Qureshi, R.N.; Kok, W.T.

    2011-01-01

    An overview is given of the recent literature on (bio) analytical applications of flow field-flow fractionation (FlFFF). FlFFF is a liquid-phase separation technique that can separate macromolecules and particles according to size. The technique is increasingly used on a routine basis in a variety

  14. Application of flow field-flow fractionation for the characterization of macromolecules of biological interest: a review

    NARCIS (Netherlands)

    R.N. Qureshi; W.T. Kok

    2011-01-01

    An overview is given of the recent literature on (bio) analytical applications of flow field-flow fractionation (FlFFF). FlFFF is a liquid-phase separation technique that can separate macromolecules and particles according to size. The technique is increasingly used on a routine basis in a variety o

  15. The lattice Boltzmann method for isothermal micro-gaseous flow and its application in shale gas flow: a review

    CERN Document Server

    Wang, Junjian; Kang, Qinjun; Rahman, Sheik S

    2016-01-01

    The lattice Boltzmann method (LBM) has experienced tremendous advances and been well accepted as a popular method of simulation of various fluid flow mechanisms on pore scale in tight formations. With the introduction of an effective relaxation time and slip boundary conditions, the LBM has been successfully extended to solve micro-gaseous related transport and phenomena. As gas flow in shale matrix is mostly in the slip flow and transition flow regimes, given the difficulties of experimental techniques to determine extremely low permeability, it appears that the computational methods especially the LBM can be an attractive choice for simulation of these micro-gaseous flows. In this paper an extensive overview on a number of relaxation time and boundary conditions used in LBM-like models for micro-gaseous flow are carried out and their advantages and disadvantages are discussed. Furthermore, potential application of the LBM in flow simulation in shale gas reservoirs on pore scale and representative elementary...

  16. Future applications of the Yang-Mills gradient flow in lattice QCD

    CERN Document Server

    Lüscher, Martin

    2013-01-01

    The Yang--Mills gradient flow has many interesting applications in lattice QCD. In this talk, some recent and possible future uses of the flow are discussed, emphasizing the underlying theoretical concepts rather than any computational aspects.

  17. Optical Electronic Bragg Reflection Sensor System with Hydrodynamic Flow Applications

    Science.gov (United States)

    Lyons, D. R.

    2003-01-01

    This project, as described in the following report, involved design and fabrication of fiber optic sensors for the detection and measurement of dynamic fluid density variations. These devices are created using UV (ultraviolet) ablation and generally modified transverse holographic fiber grating techniques. The resulting phase gratings created on or immediately underneath the flat portion of D-shaped optical waveguides are characterized as evanescent field sensing devices. The primary applications include the sensor portion of a real-time localized or distributed measurement system for hydrodynamic flow, fluid density measurements, and phase change phenomena. Several design modifications were implemented in an attempt to accomplish the tasks specified in our original proposal. In addition, we have established key collaborative relationships with numerous people and institutions.

  18. Lighting with laser diodes

    Science.gov (United States)

    Basu, Chandrajit; Meinhardt-Wollweber, Merve; Roth, Bernhard

    2013-08-01

    Contemporary white light-emitting diodes (LEDs) are much more efficient than compact fluorescent lamps and hence are rapidly capturing the market for general illumination. LEDs are also replacing halogen lamps or even newer xenon based lamps in automotive headlamps. Because laser diodes are inherently much brighter and often more efficient than corresponding LEDs, there is great research interest in developing laser diode based illumination systems. Operating at higher current densities and with smaller form factors, laser diodes may outperform LEDs in the future. This article reviews the possibilities and challenges in the integration of visible laser diodes in future illumination systems.

  19. Laser Diode Ignition (LDI)

    Science.gov (United States)

    Kass, William J.; Andrews, Larry A.; Boney, Craig M.; Chow, Weng W.; Clements, James W.; Merson, John A.; Salas, F. Jim; Williams, Randy J.; Hinkle, Lane R.

    1994-01-01

    This paper reviews the status of the Laser Diode Ignition (LDI) program at Sandia National Labs. One watt laser diodes have been characterized for use with a single explosive actuator. Extensive measurements of the effect of electrostatic discharge (ESD) pulses on the laser diode optical output have been made. Characterization of optical fiber and connectors over temperature has been done. Multiple laser diodes have been packaged to ignite multiple explosive devices and an eight element laser diode array has been recently tested by igniting eight explosive devices at predetermined 100 ms intervals.

  20. Improved Thermoelectrically Cooled Laser-Diode Assemblies

    Science.gov (United States)

    Glesne, Thomas R.; Schwemmer, Geary K.; Famiglietti, Joe

    1994-01-01

    Cooling decreases wavelength and increases efficiency and lifetime. Two improved thermoelectrically cooled laser-diode assemblies incorporate commercial laser diodes providing combination of both high wavelength stability and broad wavelength tuning which are broadly tunable, highly stable devices for injection seeding of pulsed, high-power tunable alexandrite lasers used in lidar remote sensing of water vapor at wavelengths in vicinity of 727 nanometers. Provide temperature control needed to take advantage of tunability of commercial AlGaAs laser diodes in present injection-seeding application.

  1. Discovery of a phosphor for light emitting diode applications and its structural determination, Ba(Si,Al)5(O,N)8:Eu2+.

    Science.gov (United States)

    Park, Woon Bae; Singh, Satendra Pal; Sohn, Kee-Sun

    2014-02-12

    Most of the novel phosphors that appear in the literature are either a variant of well-known materials or a hybrid material consisting of well-known materials. This situation has actually led to intellectual property (IP) complications in industry and several lawsuits have been the result. Therefore, the definition of a novel phosphor for use in light-emitting diodes should be clarified. A recent trend in phosphor-related IP applications has been to focus on the novel crystallographic structure, so that a slight composition variance and/or the hybrid of a well-known material would not qualify from either a scientific or an industrial point of view. In our previous studies, we employed a systematic materials discovery strategy combining heuristics optimization and a high-throughput process to secure the discovery of genuinely novel and brilliant phosphors that would be immediately ready for use in light emitting diodes. Despite such an achievement, this strategy requires further refinement to prove its versatility under any circumstance. To accomplish such demands, we improved our discovery strategy by incorporating an elitism-involved nondominated sorting genetic algorithm (NSGA-II) that would guarantee the discovery of truly novel phosphors in the present investigation. Using the improved discovery strategy, we discovered an Eu(2+)-doped AB5X8 (A = Sr or Ba, B = Si and Al, X = O and N) phosphor in an orthorhombic structure (A21am) with lattice parameters a = 9.48461(3) Å, b = 13.47194(6) Å, c = 5.77323(2) Å, α = β = γ = 90°, which cannot be found in any of the existing inorganic compound databases.

  2. Architectural Engineering of Nanowire Network Fine Pattern for 30 μm Wide Flexible Quantum Dot Light-Emitting Diode Application.

    Science.gov (United States)

    Fang, Yunsheng; Ding, Ke; Wu, Zhicong; Chen, Hongting; Li, Wenbo; Zhao, Sheng; Zhang, Yanli; Wang, Lei; Zhou, Jun; Hu, Bin

    2016-11-22

    Replacing rigid metal oxides with flexible alternatives as a next-generation transparent conductor is important for flexible optoelectronic devices. Recently, nanowire networks have emerged as a new type of transparent conductor and have attracted wide attention because of their all-solution-based process manufacturing and excellent flexibility. However, the intrinsic percolation characteristics of the network determine that its fine pattern behavior is very different from that of continuous films, which is a critical issue for their practical application in high-resolution devices. Herein, a simple optimization approach is proposed to address this issue through the architectural engineering of the nanowire network. The aligned and random silver nanowire networks are fabricated and compared in theory and experimentally. Remarkably, network performance can be notably improved with an aligned structure, which is helpful for external quantum efficiency and the luminance of quantum dot light-emitting diodes (QLEDs) when the network is applied as the bottom-transparent electrode. More importantly, the advantage introduced by network alignment is also of benefit to fine pattern performance, even when the pattern width is narrowed to 30 μm, which leads to improved luminescent properties and lower failure rates in fine QLED strip applications. This paradigm illuminates a strategy to optimize nanowire network based transparent conductors and can promote their practical application in high-definition flexible optoelectronic devices.

  3. Applications of flow cytometry in environmental microbiology and biotechnology.

    Science.gov (United States)

    Bergquist, Peter L; Hardiman, Elizabeth M; Ferrari, Belinda C; Winsley, Tristrom

    2009-05-01

    Flow cytometry (FCM) is a technique for counting, examining and sorting microscopic particles suspended in a stream of fluid. It uses the principles of light scattering, light excitation and the emission from fluorescent molecules to generate specific multiparameter data from particles and cells. The cells are hydrodynamically focussed in a sheath solution before being intercepted by a focused light source provided by a laser. FCM has been used primarily in medical applications but is being used increasingly for the examination of individual cells from environmental samples. It has found uses in the isolation of both culturable and hitherto non-culturable bacteria present infrequently in environmental samples using appropriate growth conditions. FCM lends itself to high-throughput applications in directed evolution for the analysis of single cells or cell populations carrying mutant genes. It is also suitable for encapsulation studies where individual bacteria are compartmentalised with substrate in water-in-oil-in-water emulsions or with individual genes in transcriptional/translational mixtures for the production of mutant enzymes. The sensitivity of the technique has allowed the examination of gene optimisation by a procedure known as random or neutral drift where screening and selection is based on the retention of some predetermined level of activity through multiple rounds of mutagenesis.

  4. Large deviations for stochastic flows and their applications

    Institute of Scientific and Technical Information of China (English)

    GAO; Fuqing(

    2001-01-01

    [1]Yoshida, N., A large deviation principle for (r,p)-capacities on the Wiener space, Proba. Th. Rel. Fields, 1993, 94:473-488.[2]Gao, F. Q., Large deviations of (r,p)-capacities for diffusion processes, Advances in Math. (in Chinese), 1996, 25:500-509.[3]Millet, A., Nualart, D., Sanz, M., Large deviations for a class of anticipating stochastic differential equations, Ann.Prob.. 1993, 20: 1902-1931.[4]Millet, A., Nualart, D., Sans, M., Composition of large deviation principles and applications, in Stochastic Analysis (ed.Mayer, E. ), San Diego: Academic Press, 1991, 383-395.[5]Ocone, D., Pardoux, E., A generalized Ito-Ventzell formula, Applications to a class of anticipating stochastic differentialequations, Ann. Inst. Poincaré, Sect. B, 1989, 25: 39-71.[6]Malliavin, P., Nualart, D., Quasi sure analysis of stochastic flows and Banach space valued smooth functionals on the Wiener space, J. Funct. Anal., 1993, 112: 287-317.[7]Huang, Z., Ren, J. , Quasi sure stochastic flows, Stoch. Stoch. Rep. , 1990, 33: 149-157.[8]Gao, E. Q., Large deviations for diffusion processes in Hslder norm, Advances in Math. (in Chinese), 1997, 26: 147-158.[9]Arous, B. G. , Ledoux, M., Grandes déviations sur la déviations de Freidlin-Wentzell en norme holderienne, 1994, Lecr.Notes in Math. , 1994, 987: 1583.[10]Baldi, P. , Sanz, M. , Une remarque sur la théorie des grandes deviations, Lect. Notes Math., 1991, 1485: 345-348.[11]Airault, H., Malliavin, P., Intégration géometrique sur l'espace de Wiener, Bull. Sci. Math., 1988, 112: 3-52.[12]Ikeda, N. , Watanabe, S., Stochastic Differential Equations and Diffusion Processes, 2nd ed., Amsterdam-Kodansha-Tokyo:North-Holland, 1988.[13]Malliavin, P., Stochastic Analysis, Grundlehren der Mathematischen Wissenschaften 313, Berlin: Springer-Verlag, 1997.[14]Brzezniak, Z., Elworthy, K. D., Stochastic flows of diffeomorphism. In Stochastic Analysis and Applications (eds. Davies,I. M.. Truman

  5. The Throughput Flow Constraint Theorem and its Applications

    Directory of Open Access Journals (Sweden)

    Michael T. Todinov

    2014-01-01

    Full Text Available The paper states and proves an important result related to the theory of flow networks with disturbed flows:“the throughput flow constraint in any network is always equal to the throughput flow constraint in its dual network”. After the failure or congestion of several edges in the network, the throughput flow constraint theorem provides the basis of a very efficient algorithm for determining the edge flows which correspond to the optimal throughput flow from sources to destinations which is the throughput flow achieved with the smallest amount of generation shedding from the sources. In the case where a failure of an edge causes a loss of the entire flow through the edge, the throughput flow constraint theorem permits the calculation of the new maximum throughput flow to be done in time, where m is the number of edges in the network.In this case, the new maximum throughput flow is calculated by inspecting the network only locally, in the vicinity of the failed edge, without inspecting the rest of the network. The superior average running time of the presented algorithm, makes it particularly suitable for decongesting overloaded transmission links of telecommunication networks, in real time.In the paper, it is also shown that the deliberate choking of flows along overloaded edges, leading to a generation of momentary excess and deficit flow, provides a very efficient mechanism for decongesting overloaded branches.

  6. Electronic Characterization of Au/DNA/ITO Metal-Semiconductor-Metal Diode and Its Application as a Radiation Sensor.

    Science.gov (United States)

    Al-Ta'ii, Hassan Maktuff Jaber; Periasamy, Vengadesh; Amin, Yusoff Mohd

    2016-01-01

    Deoxyribonucleic acid or DNA molecules expressed as double-stranded (DSS) negatively charged polymer plays a significant role in electronic states of metal/silicon semiconductor structures. Electrical parameters of an Au/DNA/ITO device prepared using self-assembly method was studied by using current-voltage (I-V) characteristic measurements under alpha bombardment at room temperature. The results were analyzed using conventional thermionic emission model, Cheung and Cheung's method and Norde's technique to estimate the barrier height, ideality factor, series resistance and Richardson constant of the Au/DNA/ITO structure. Besides demonstrating a strongly rectifying (diode) characteristic, it was also observed that orderly fluctuations occur in various electrical parameters of the Schottky structure. Increasing alpha radiation effectively influences the series resistance, while the barrier height, ideality factor and interface state density parameters respond linearly. Barrier height determined from I-V measurements were calculated at 0.7284 eV for non-radiated, increasing to about 0.7883 eV in 0.036 Gy showing an increase for all doses. We also demonstrate the hypersensitivity phenomena effect by studying the relationship between the series resistance for the three methods, the ideality factor and low-dose radiation. Based on the results, sensitive alpha particle detectors can be realized using Au/DNA/ITO Schottky junction sensor.

  7. "Quasi-freestanding" graphene-on-single walled carbon nanotube electrode for applications in organic light-emitting diode.

    Science.gov (United States)

    Liu, Yanpeng; Jung, Eun; Wang, Yu; Zheng, Yi; Park, Eun Ji; Cho, Sung Min; Loh, Kian Ping

    2014-03-12

    An air-stable transparent conductive film with "quasi-freestanding" graphene supported on horizontal single walled carbon nanotubes (SWCNTs) arrays is fabricated. The sheet resistance of graphene films stacked via layer-by-layer transfer (LBL) on quartz, and modified by 1-Pyrenebutyric acid N-hydroxysuccinimide ester (PBASE), is reduced from 273 Ω/sq to about 76 Ω/sq. The electrical properties are stable to heat treatment (up to 200 ºC) and ambient exposure. Organic light-emitting diodes (OLEDs) constructed of this carbon anode (T ≈ 89.13% at 550 nm) exhibit ≈88% power efficiency of OLEDs fabricated on an ITO anode (low turn on voltage ≈3.1 eV, high luminance up to ≈29 490 cd/m(2) , current efficiency ≈14.7 cd/A). Most importantly, the entire graphene-on-SWCNT hybrid electrodes can be transferred onto plastic (PET) forming a highly-flexible OLED device, which continues to function without degradation in performance at bending angles >60°.

  8. Characterizing the resolvability of real superluminescent diode sources for application to optical coherence tomography using a low coherence interferometry model

    Science.gov (United States)

    Jansz, Paul Vernon; Richardson, Steven; Wild, Graham; Hinckley, Steven

    2014-08-01

    The axial resolution is a critical parameter in determining whether optical coherent tomography (OCT) can be used to resolve specific features in a sample image. Typically, measures of resolution have been attributed to the light source characteristics only, including the coherence length and the point spread function (PSF) width of the OCT light sources. The need to cost effectively visualize the generated PSF and OCT cross-correlated interferogram (A-scan) using many OCT light sources have led to the extrinsic evolution of the OCT simulation model presented. This research indicated that empirical resolution in vivo, as well as depending on the light source's spectral characteristics, is also strongly dependent on the optical characteristics of the tissue, including surface reflection. This research showed that this reflection could be digitally removed from the A-scan of an epithelial model, enhancing the stratum depth resolution limit (SDRL) of the subsurface tissue. Specifically, the A-scan portion above the surface, the front surface interferogram, could be digitally subtracted, rather than deconvolved, from the subsurface part of each A-scan. This front surface interferogram subtraction resulted in considerably reduced empirical SDRLs being much closer to the superluminescent diodes' resolution limits, compared to the untreated A-scan results.

  9. Fabrication of silver nanowires and metal oxide composite transparent electrodes and their application in UV light-emitting diodes

    Science.gov (United States)

    Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Wang, Chunliang; Liu, Yichun

    2016-08-01

    In this paper, we prepared the silver nanowires (AgNWs)/aluminum-doped zinc oxide (AZO) composite transparent conducting electrodes for n-ZnO/p-GaN heterojunction light emitting-diodes (LEDs) by drop casting AgNW networks and subsequent atomic layer deposition (ALD) of AZO at 150 °C. The contact resistances between AgNWs were dramatically reduced by pre-annealing in the vacuum chamber before the ALD of AZO. In this case, AZO works not only as the conformal passivation layer that protects AgNWs from oxidation, but also as the binding material that improves AgNWs adhesion to substrates. Due to the localized surface plasmons (LSPs) of the AgNWs resonant coupling with the ultraviolet (UV) light emission from the LEDs, a higher UV light extracting efficiency is achieved from LEDs with the AgNWs/AZO composite electrodes in comparison with the conventional AZO electrodes. Additionally, the antireflective nature of random AgNW networks in the composite electrodes caused a broad output light angular distribution, which could be of benefit to certain optoelectronic devices like LEDs and solar cells.

  10. External cavity based single mode Fabry-Pérot laser diode and its application towards all-optical digital circuits

    Science.gov (United States)

    Nakarmi, Bikash; Zhang, Xuping; Won, Yong Hyub

    2012-11-01

    We have proposed a novel approach of realizing all-optical logic gates and combinational circuit using external cavity based single mode Fabry-Pérot laser diodes (SMFP-LDs). Different techniques and critical parameters for injection locking the any one of the modes of SMFP-LDs are discussed. Taking consideration of wavelength detuning and input injected power, we have proposed and demonstrated multi-input injection locking, supporting beam injection locking with the conventional injection locking which are used for demonstrating different logic gates (NAND, AND, XNOR, XOR, NOT, NOR) and digital circuits (Half adder and Comparator). Since we have used SMFP-LDs, there is no requirement of additional probe beam and associated components as required by other optical technologies making the realization simple in configuration, cost effective and power efficient. Clear output waveforms, eye diagrams, risingfalling times and BER are presented to verify the proposed method. All-optical logic units and digital circuit are demonstrated at the data rate of 10 Gbps with the waveform of NRZ signal waveform and measured eye diagram and BER of the PRBS of 231-1 signal. The maximum power penalty among all demonstrated units is below 1.4 dB at the BER of 10-9.

  11. Multiple and broad frequency response Gunn diodes

    Science.gov (United States)

    Pilgrim, N. J.; Macpherson, R. F.; Khalid, A.; Dunn, G. M.; Cumming, D. R. S.

    2009-10-01

    Gunn diodes, operating in transit time mode, are usually thought of as incapable of generating power at multiple frequencies or over a broad frequency range. In this paper, we report experimental results showing that these diodes can generate power at several frequencies and, using Monte Carlo simulations of both planar and vertical devices, we offer an explanation of how this unusual behaviour may come into being and suggest possible applications for this novel device.

  12. Varactor diodes for millimeter and submillimeter wavelengths

    Science.gov (United States)

    Rizzi, Brian J.; Hesler, Jeffrey L.; Dossal, Hasan; Crowe, Thomas W.

    1992-01-01

    Whisker-contacted GaAs Schottky barrier varactor diodes are the most common high-frequency multiplier element in use today. They are inherently simple devices that have very high frequency response and have been used to supply local oscillator power for Schottky heterodyne receivers to frequencies approaching 700 GHz. This paper discusses the development of improved varactor diode technology for space based applications at millimeter and submillimeter wavelengths.

  13. Megahertz organic/polymer diodes

    Science.gov (United States)

    Katz, Howard Edan; Sun, Jia; Pal, Nath Bhola

    2012-12-11

    Featured is an organic/polymer diode having a first layer composed essentially of one of an organic semiconductor material or a polymeric semiconductor material and a second layer formed on the first layer and being electrically coupled to the first layer such that current flows through the layers in one direction when a voltage is applied in one direction. The second layer is essentially composed of a material whose characteristics and properties are such that when formed on the first layer, the diode is capable of high frequency rectifications on the order of megahertz rectifications such as for example rectifications at one of above 100KHz, 500KhZ, IMHz, or 10 MHz. In further embodiments, the layers are arranged so as to be exposed to atmosphere.

  14. Green Synthesis of InP/ZnS Core/Shell Quantum Dots for Application in Heavy-Metal-Free Light-Emitting Diodes.

    Science.gov (United States)

    Kuo, Tsung-Rong; Hung, Shih-Ting; Lin, Yen-Ting; Chou, Tzu-Lin; Kuo, Ming-Cheng; Kuo, Ya-Pei; Chen, Chia-Chun

    2017-09-19

    Quantum dot light-emitting diodes (QD-LEDs) have been considered as potential display technologies with the characterizations of high color purity, flexibility, transparency, and cost efficiency. For the practical applications, the development of heavy-metal-free QD-LEDs from environment-friendly materials is the most important issue to reduce the impacts on human health and environmental pollution. In this work, heavy-metal-free InP/ZnS core/shell QDs with different fluorescence were prepared by green synthesis method with low cost, safe, and environment-friendly precursors. The InP/ZnS core/shell QDs with maximum fluorescence peak at ~ 530 nm, superior fluorescence quantum yield of 60.1%, and full width at half maximum of 55 nm were applied as an emission layer to fabricate multilayered QD-LEDs. The multilayered InP/ZnS core/shell QD-LEDs showed the turn-on voltage at ~ 5 V, the highest luminance (160 cd/m(2)) at 12 V, and the external quantum efficiency of 0.223% at 6.7 V. Overall, the multilayered InP/ZnS core/shell QD-LEDs reveal potential to be the heavy-metal-free QD-LEDs for future display applications.

  15. New heavy crude oil flow improver increases delivery : application scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, J.; Johnston, R.; Lauzon, P. [ConocoPhillips Specialty Products Inc., Houston, TX (United States)

    2009-07-01

    Flow improvers or drag reducing agents have been used for over 25 years as a method to increase fluid flow in hydrocarbon pipelines. The technology is effective in refined projects, light and medium crude oils. This paper presented a new development in flow improver technology that allows treatment of heavy crude oil slates. It discussed case studies of flow improver treatment of heavy oils in various pipeline system as well as factors that affect commercial success. tabs., figs.

  16. Flow Separation and Turbulence in Jet Pumps for Thermoacoustic Applications

    NARCIS (Netherlands)

    Oosterhuis, Joris P.; Verbeek, Anton A.; Bühler, Simon; Wilcox, Douglas; Meer, van der Theo H.

    2016-01-01

    The effect of flow separation and turbulence on the performance of a jet pump in oscillatory flows is investigated. A jet pump is a static device whose shape induces asymmetric hydrodynamic end effects when placed in an oscillatory flow. This will result in a time-averaged pressure drop which can be

  17. Fabrication of Metal-Deposited Indium Tin Oxides: Its Applications to 385 nm Light-Emitting Diodes.

    Science.gov (United States)

    Kim, Min Ju; Kim, Tae Geun

    2016-03-01

    We report performance improvements in near-ultraviolet (NUV) light-emitting diodes (LEDs) using various metal-doped indium tin oxide (ITO/metals). Metals with an orbital energy gap greater than that of an In atom (e.g., Ti, Ga, Ge, and Al) are deposited on ITO, and subsequent annealing is performed to improve optical transmittance of ITO due to effective bandgap increase via the linear combination of atomic orbitals, as well as electrical conductivity; thus, current spreading via metal-doping effect at the surface of ITO. As a result, the ITO/metals (annealed at 550 °C, 1 min) exhibit 90.5-94.7% transmittance at 385 nm and a specific contact resistance of 2.1-3.0 × 10(-3) Ω cm(2), whereas the reference ITOs exhibit 76.5-89.5% and 3.2-4.5 × 10(-3) Ω cm(2), respectively. Compared to NUV LEDs using conventional ITO (60 nm), the InGaN/AlGaInN NUV LED using ITO (110 nm)/metal (3 nm) on average exhibits a 70% increase in light output power at 100 mA and a 2% decrease in forward voltage at 20 mA, with more uniform and brighter emission images. We also identified the origin for the improvement by analyzing the surface of ITO/metals using X-ray photoelectron spectroscopy and Auger electron spectroscopy. This approach could offer a simple, effective way to enhance the overall efficiency of conventional NUV LEDs using ITO.

  18. A combined application of tunable diode laser absorption spectroscopy and isothermal micro-calorimetry for calorespirometric analysis.

    Science.gov (United States)

    Brueckner, David; Solokhina, Anna; Krähenbühl, Stephan; Braissant, Olivier

    2017-08-01

    Calorespirometry is the simultaneous analysis of the rate of heat emission (Rq), O2 consumption (RO2) and CO2 production (RCO2) by living systems such as tissues or organism cultures. The analysis provides useful knowledge about thermodynamic parameters relevant for e.g. biotechnology where parameter based yield maximization (fermentation) is relevant. The determination of metabolism related heat emission is easy and normally done by a calorimeter. However, measuring the amount of consumed O2 and produced CO2 can be more challenging, as additional preparation or instrumentation might be needed. Therefore, tunable diode laser absorption spectroscopy (TDLAS) was investigated as an alternative approach for respirometric analysis in order to facilitate the data collection procedure. The method determines by a spectroscopic laser non-invasively CO2 and O2 gas concentration changes in the respective vial headspaces. The gathered growth data from Pseudomonas aeruginosa cultured in two different scarce media was used to compute respiratory quotient (RQ) and calorespirometric ratios (CRCO2 [Rq/RCO2], CRO2 [Rq/RO2]). A comparison of the computed (experimental) values (for RQ, CRCO2 and CRO2) with values reported in the literature confirmed the appropriateness of TDLAS in calorespirometric studies. Thus, it could be demonstrated that TDLAS is a well-performing and convenient way to evaluate non-invasively respiratory rates during calorespirometric studies. Therefore, the technique is definitively worth to be investigated further for its potential use in research and in diverse productive environments. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Numerical modeling of fluid flow with rafts: An application to lava flows

    Science.gov (United States)

    Tsepelev, Igor; Ismail-Zadeh, Alik; Melnik, Oleg; Korotkii, Alexander

    2016-07-01

    Although volcanic lava flows do not significantly affect the life of people, its hazard is not negligible as hot lava kills vegetation, destroys infrastructure, and may trigger a flood due to melting of snow/ice. The lava flow hazard can be reduced if the flow patterns are known, and the complexity of the flow with debris is analyzed to assist in disaster risk mitigation. In this paper we develop three-dimensional numerical models of a gravitational flow of multi-phase fluid with rafts (mimicking rigid lava-crust fragments) on a horizontal and topographic surfaces to explore the dynamics and the interaction of lava flows. We have obtained various flow patterns and spatial distribution of rafts depending on conditions at the surface of fluid spreading, obstacles on the way of a fluid flow, raft landing scenarios, and the size of rafts. Furthermore, we analyze two numerical models related to specific lava flows: (i) a model of fluid flow with rafts inside an inclined channel, and (ii) a model of fluid flow from a single vent on an artificial topography, when the fluid density, its viscosity, and the effusion rate vary with time. Although the studied models do not account for lava solidification, crust formation, and its rupture, the results of the modeling may be used for understanding of flows with breccias before a significant lava cooling.

  20. Perturbation theorems for Hele-Shaw flows and their applications

    CERN Document Server

    Lin, Yu-Lin

    2010-01-01

    In this work, we give a perturbation theorem for strong polynomial solutions to the zero surface tension Hele-Shaw equation driven by injection or suction, so called the Polubarinova-Galin equation. This theorem enables us to explore properties of solutions with initial functions close to but are not polynomial. Applications of this theorem are given in the suction or injection case. In the former case, we show that if the initial domain is close to a disk, most of fluid will be sucked before the strong solution blows up. In the later case, we obtain precise large-time rescaling behaviors for large data to Hele-Shaw flows in terms of invariant Richardson complex moments. This rescaling behavior result generalizes a recent result regarding large-time rescaling behavior for small data in terms of moments. As a byproduct of a theorem in this paper, a short proof of existence and uniqueness of strong solutions to the Polubarinova-Galin equation is given.

  1. Evaluation of Light-Emitting Diode (LED-660 Nm) Application over Primary Osteoblast-Like Cells on Titanium Surfaces: An In Vitro Study

    Science.gov (United States)

    Cankaya, Abdulkadir Burak; Erdem, Mehmet Ali; Erdem, Arzu Pınar; Erguven, Mine; Aybar, Buket; Kasapoglu, Cetin; Bilir, Ayhan

    2011-01-01

    Background: The goal of this study was to evaluate the behavior of neonatal rat calvarial osteoblast-like cells cultured on different implant surfaces and exposed once or three times to a 660-nm light-emitting diode (LED). Methods: An LED with a 660-nm wavelength was applied once or three times to cultured cells on standard and modified sandblasted acid-etched surfaces (SLA and SLActive; Straumann, Basel, Switzerland). To analyze the effect of the LED on cell proliferation, numbers, and viability, cells were cultured on titanium discs, and measurements were taken after 72 h. Cell proliferation rates were assessed using a bromodeoxyuridine immunohistochemical technique. Cell morphologies were evaluated by scanning electron microscopy (SEM). Results: Osteoblast-like cells proliferated on all tested surfaces, with differences among groups in cell counts and DNA synthesis values. The application of one LED treatment caused a significant increase in cell count in the SLActive group in comparison with the SLA group (p = 0.001), whereas the application of three LED treatments caused a significant decrease in cell count in the SLA group compared with the SLActive group (p < 0.001). After 72 h, the number of cells was highest in the SLActive group exposed once to the LED. Conclusions: One LED application in the SLActive group resulted in significantly increased cell numbers. However, these findings were not exactly compatible with the SEM findings, which demonstrated fewer cells and weak attachments between cells and to the surface. Thus, further studies using different LED application times are needed to clarify the reason for the increased number of cells that are apparently incapable of attaching to the titanium surfaces after 72 h. PMID:22022211

  2. Terahertz Diode Development

    Science.gov (United States)

    2009-03-23

    Gunn Diode , Negative Differential Resistance, Ballistic Transport, GaN, THz, Co-planar Resonator 16. SECURITY CLASSIFICATION OF: REPORT U b...Report DATES COVERED (From - Jo) 1 January 2004- 31 December 2008 4. TITLE AND SUBTITLE Terahertz Diode Development 5a. CONTRACT NUMBER N00014...current-voltage oscillations at the terminals of the diode at a frequency which is, to first order, determined by the average transit time of the EAL

  3. STUDY AND APPLICATION OF STEADY FLOW AND UNSTEADY FLOW MATHEMATICAL MODEL FOR CHANNEL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the Preissmann implicit scheme for the one-dimensional Saint-Venant equation, the mathematical model for one-dimensional river networks and canal networks was developed and the key issues on the model were expatiated particularly in this article. This model applies the method of three-steps solution for channel-junction-channel to simulate the river networks, and the Gauss elimination method was used to calculate the sparse matrix. This model was applied to simulate the tree-type irrigation canal networks, complex looped channel networks and the Lower Columbia Slough networks. The results of water level and discharge agree with the data from the Adlul and field data. The model is proved to be robust for simulating unsteady flows in river networks with various degrees of complex structure. The calculated results show that this model is useful for engineering applications in complicated river networks. Future research was recommended to focus on setting up ecological numerical model of water quality in river networks and canal networks.

  4. Utilization of Different Variables for the Visualization of Fluid Flows:Application to Instantaneous Channel Flows

    Institute of Scientific and Technical Information of China (English)

    Gérard J. Poitras; L.-Emmanuel Brizzi; Yves Gagnon

    2001-01-01

    The results of different numerical algorithms for the computation of unsteady fluid flows are used to visualize different variables of the flow. In particular, the instantaneous vorticity, velocity and pressure fields, along with streamline plots, are presented as a function of time inside a visualization window of the computational domain.The different forms of visualization are used to analyze the flow inside a two-dimensional channel incorporating an obstacle, which can represent several interesting flows such as the flow over electronic components, heat transfer devices and buildings.

  5. Large eddy simulations of flow and mixing in jets and swirl flows: application to a gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Schluter, J.U.

    2000-07-01

    Large Eddy Simulations (LES) are an accepted tool in turbulence research. Most LES investigations deal with low Reynolds-number flows and have a high spatial discretization, which results in high computational costs. To make LES applicable to industrial purposes, the possibilities of LES to deliver results with low computational costs on high Reynolds-number flows have to be investigated. As an example, the cold flow through the Siemens V64.3A.HR gas turbine burner shall be examined. It is a gas turbine burner of swirl type, where the fuel is injected on the surface of vanes perpendicular to the main air flow. The flow regime of an industrial gas turbine is governed by several flow phenomena. The most important are the fuel injection in form of a jet in cross flow (JICF) and the swirl flow issuing into a combustion chamber. In order to prove the ability of LES to deal with these flow phenomena, two numerical investigations were made in order to reproduce the results of experimental studies. The first one deals with JICF. It will be shown that the reproduction of three different JICF is possible with LES on meshes with a low number of mesh points. The results are used to investigate the flow physics of the JICF, especially the merging of two adjacent JICFs. The second fundamental investigation deals with swirl flows. Here, the accuracy of an axisymmetric assumption is examined in detail by comparing it to full 3D LES computations and experimental data. Having demonstrated the ability of LES and the flow solver to deal with such complex flows with low computational efforts, the LES approach is used to examine some details of the burner. First, the investigation of the fuel injection on a vane reveals that the vane flow tends to separate. Furthermore the tendency of the fuel jets to merge is shown. Second, the swirl flow in the combustion chamber is computed. For this investigation the vanes are removed from the burner and swirl is imposed as a boundary condition. As

  6. Method and its application of the momentum model for debris flow risk zoning

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In order to ascertain the distribution of flow depth and velocity of debris flow, the combination of numerical modeling and the GIS technology has been used to simulate the movement process of debris flow out of the outlet. The main model of momentum classification of risk zoning of debris flow is Z=Khv. Based on the distribution of the velocity and depth of debris flow, the distribution of momentum can be ascertained. Thereby the classification of risk zoning of debris flow can be worked out. A case study of Chacaito Valley in Caracas, Venezuela, is presented to illustrate the application of the method.

  7. An application of numerical methods to the prediction of strata methane flow in longwall mining

    OpenAIRE

    Ediz, I.G.

    1991-01-01

    This research describes an application of numerical methods for the prediction of strata methane flow into mine workings around a longwall coal face employing methane drainage. This method of methane prediction was developed by solving the time-dependent gas flow equation using the finite element analysis. Having obtained the gas pressure distribution throughout the finite element mesh, a mass flow equation was derived to calculate methane flow rate for a given mining boundary. A computer pro...

  8. Asymmetrical flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry for sizing SeNPs for packaging applications

    Science.gov (United States)

    Palomo-Siguero, María; Vera, Paula; Echegoyen, Yolanda; Nerin, Cristina; Cámara, Carmen; Madrid, Yolanda

    2017-06-01

    This paper describes the application of Asymmetrical Flow Field-Flow Fractionation (AF4) coupled to diode array detector (DAD) and inductively coupled plasma mass spectrometry (AF4-UV-ICP-MS) to characterize selenium nanoparticles (SeNPs) in an aqueous acrylic adhesive to be used in a multilayer food packaging material. SeNPs were synthesized using a solution-phase approach based on the reduction of selenite with ascorbic acid in presence of different stabilizers compatible with food industry such as polysaccharides (chitosan (poly(D-glucosamine) and hydroxyethylcellulose (HEC)) and non-ionic surfactants (Triton X-100 (t-octylphenoxypolyethoxyethanol), 2,4,7,9-tetramethyl 5decyne-4,7-diol ethoxylate, and isotridecanol ethoxylate). Several parameters such as pH, ascorbic acid and stabilizers concentration, and compatibility of the stabilizer with the adhesive were evaluated. SeNPs suspensions with spherical morphology were obtained except when isotridecanol ethoxylate was employed which provides SeNPs with a nanorod morphology. AF4-DAD-ICP-MS was further applied for sizing the different SeNPs preparations. DAD was used as detector for selecting the best AF4 separation conditions before coupling to ICP-MS to ensure unequivocal identification of NPs. AF4 calibration with polystyrene latex (PSL) beads of known sizes allowed size determination of the different SeNPs. The following estimated hydrodynamic sizes (expressed as the mean ± standard deviation, n = 6 replicates) were found: chitosan-SeNPs- (26 ± 3 nm), TritonX100-SeNPs (22 ± 10 nm) HEC- SeNPs (91 ± 8 nm) and 2,4,7,9-tetramethyl 5decyne-4,7-diol ethoxylate- SeNPs (59 ± 4 nm). The proposed methodology was successfully applied to the characterization in terms of size of aqueous acrylic adhesives containing SeNPs Results from AF4-ICP-MS and TEM shown that only those SeNPs obtained with non-ionic surfactants and HEC were compatible with the adhesive. The results reported here evidence the usefulness of AF4-ICP

  9. Applications of texture mapping to volume and flow visualization

    Energy Technology Data Exchange (ETDEWEB)

    Max, N.; Crawfis, R.; Becker, B.

    1995-05-01

    The authors describe six visualization methods which take advantage of hardware polygon scan conversion, texture mapping, and compositing, to give interactive viewing of 3D scalar fields, and motion for 3D flows. For volume rendering, these are splatting of an optimized 3D reconstruction filter, and tetrahedral cell projection using a texture map to provide the exponential per pixel necessary for accurate opacity calculation. For flows, these are the above tetrahedral projection method for rendering the ``flow volume`` dyed after passing through a dye releasing polygon, ``splatting`` of cycled anisotropic textures to provide flow direction and motion visualization, splatting motion blurred particles to indicate flow velocity, and advecting a texture directly to show the flow motion. All these techniques are tailored to take advantage of existing graphics pipelines to produce interactive visualization tools.

  10. Applications of texture mapping to volume and flow visualization

    Energy Technology Data Exchange (ETDEWEB)

    Max, N.; Crawfis, R.; Becker, B.

    1995-05-01

    The authors describe six visualization methods which take advantage of hardware polygon scan conversion, texture mapping, and compositing, to give interactive viewing of 3D scalar fields, and motion for 3D flows. For volume rendering, these are splatting of an optimized 3D reconstruction filter, and tetrahedral cell projection using a texture map to provide the exponential per pixel necessary for accurate opacity calculation. For flows, these are the above tetrahedral projection method for rendering the ``flow volume`` dyed after passing through a dye releasing polygon, ``splatting`` of cycled anisotropic textures to provide flow direction and motion visualization, splatting motion blurred particles to indicate flow velocity, and advecting a texture directly to show the flow motion. All these techniques are tailored to take advantage of existing graphics pipelines to produce interactive visualization tools.

  11. Core flow control system for field applications; Sistema de controle de core-flow

    Energy Technology Data Exchange (ETDEWEB)

    Granzotto, Desiree G.; Adachi, Vanessa Y.; Bannwart, Antonio C.; Moura, Luiz F.M. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Sassim, Natache S.D.A. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Centro de Estudo do Petroleo (CEPETRO); Carvalho, Carlos H.M. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The significant heavy oil reserves worldwide and the presently high crude oil prices make it essential the development of technologies for heavy oil production and transportation. Heavy oils, with their inherent features of high viscosity (100- 10,000 cP) and density (below 20 deg API) require specific techniques to make it viable their flow in pipes at high flow rates. One of the simplest methods, which do not require use of heat or diluents, is provided by oil-water annular flow (core-flow). Among the still unsolved issues regarding core-flow is the two-phase flow control in order to avoid abrupt increases in the pressure drop due to the possible occurrence of bad water-lubricated points, and thus obtain a safe operation of the line at the lowest possible water-oil ratio. This work presents results of core flow tests which allow designing a control system for the inlet pressure of the line, by actuating on the water flow rate at a fixed oil flow rate. With the circuit model and the specified controller, simulations can be done to assess its performance. The experiments were run at core-flow circuit of LABPETRO-UNICAMP. (author)

  12. Micro fibre optic flow checker for the medical analysis application.

    Science.gov (United States)

    Wang, Danping

    2007-01-01

    Two micro fibre optic flow checkers are presented in this paper. They are used for a medical analysis to control a solvent flow up to 1microl/min resolution. A fibre optic sensor as well as a hydraulic system are the principle components of these flow checkers. This paper describes the principle and the experiment setup. It gives the linearity, the repeatability and the stability results.

  13. Air entrainment in open channel flows. Application to spillways

    Energy Technology Data Exchange (ETDEWEB)

    Chanson, H. (Queensland Univ., St. Lucia (Australia))

    1992-01-01

    In open channel flows an important design parameter is the amount of entrained air. The presence of air in high velocity flows or steep chutes increases the bulk of the flow and this is a design parameter that determines the height of chute sidewalls. Furthermore the presence of air within the boundary layer reduces the shear stress between flow layers and hence the shear forces. The resulting increase of fluid motion must be taken in account when designing ski jump and stilling basin downstream of a spillway. Besides the presence of air within high-velocity flows may prevent or reduce cavitation damage. Estimation of the quantity of air entrained along the spillway is required by the design engineer when sitting aerators to artificially introduce more air, or determining whether aerators are required. Recently air entrainment on chutes also been recognized for its contribution to air-water transfer of atmospheric gases such as oxygen and nitrogen. This article describes a general method to compute the flow characteristics of self-aerated flows. Firstly the uniform flow conditions are presented and comparisons will be made between model and prototype results. Then the basic equations for gradually varied aerated flows will be developed, and these results are discussed and compared with experimental data. 28 refs., 8 figs., 3 tabs.

  14. Vortex sinks with axial flow: Solution and applications

    Science.gov (United States)

    Shtern, Vladimir; Borissov, Anatoly; Hussain, Fazle

    1997-10-01

    In this paper we develop a new class of analytical solutions of the Navier-Stokes equations and suggest ways to predict and control complex swirling flows. We consider vortex sinks on curved axisymmetric surfaces with an axial flow and obtain a five-parameter solution family that describes a large variety of flow patterns and models fluid motion in a cylindrical can, whirlpools, tornadoes, and cosmic swirling jets. The singularity of these solutions on the flow axis is removed by matching them with swirling jets. The resulting composite solutions describe flows, consisting of up to seven separation regions (recirculatory "bubbles" and vortex rings), and model flows in the Ranque-Hilsch tube, in the meniscus of electrosprays, in vortex breakdown, and in an industrial vortex burner. The analytical solutions allow a clear understanding of how different control parameters affect the flow and guide selection of optimal parameter values for desired flow features. The approach permits extension to swirling flows with heat transfer and chemical reaction, and have the potential of being significantly useful for further detailed investigation by direct or large-eddy numerical simulations as well as laboratory experimentation.

  15. Stochastic evolutions of dynamic traffic flow modeling and applications

    CERN Document Server

    Chen, Xiqun (Michael); Shi, Qixin

    2015-01-01

    This book reveals the underlying mechanisms of complexity and stochastic evolutions of traffic flows. Using Eulerian and Lagrangian measurements, the authors propose lognormal headway/spacing/velocity distributions and subsequently develop a Markov car-following model to describe drivers’ random choices concerning headways/spacings, putting forward a stochastic fundamental diagram model for wide scattering flow-density points. In the context of highway onramp bottlenecks, the authors present a traffic flow breakdown probability model and spatial-temporal queuing model to improve the stability and reliability of road traffic flows. This book is intended for researchers and graduate students in the fields of transportation engineering and civil engineering.

  16. Low-Temperature Facile Synthesis of Sb-Doped p-Type ZnO Nanodisks and Its Application in Homojunction Light-Emitting Diode.

    Science.gov (United States)

    Baek, Sung-Doo; Biswas, Pranab; Kim, Jong-Woo; Kim, Yun Cheol; Lee, Tae Il; Myoung, Jae-Min

    2016-05-25

    This study explores low-temperature solution-process-based seed-layer-free ZnO p-n homojunction light-emitting diode (LED). In order to obtain p-type ZnO nanodisks (NDs), antimony (Sb) was doped into ZnO by using a facile chemical route at 120 °C. The X-ray photoelectron spectra indicated the presence of (SbZn-2VZn) acceptor complex in the Sb-doped ZnO NDs. Using these NDs as freestanding templates, undoped n-type ZnO nanorods (NRs) were epitaxially grown at 95 °C to form ZnO p-n homojunction. The homojunction with a turn-on voltage of 2.5 V was found to be significantly stable up to 100 s under a constant voltage stress of 5 V. A strong orange-red emission was observed by the naked eye under a forward bias of 5 V. The electroluminescence spectra revealed three major peaks at 400, 612, and 742 nm which were attributed to the transitions from Zni to VBM, from Zni to Oi, and from VO to VBM, respectively. The presence of these deep-level defects was confirmed by the photoluminescence of ZnO NRs. This study paves the way for future applications of ZnO homojunction LEDs using low-temperature and low-cost solution processes with the controlled use of native defects.

  17. Effects of neutral particle beam on nano-crystalline silicon thin films, with application to thin film transistor backplane for flexible active matrix organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jin Nyoung; Song, Byoung Chul; Lee, Dong Hyeok [Dept. of Display and Semiconductor Physics, Korea University, Chungnam (Korea, Republic of); Yoo, Suk Jae; Lee, Bonju [National Fusion Research Institute, 52, Yuseong-Gu, Deajeon, 305-333 (Korea, Republic of); Hong, MunPyo, E-mail: goodmoon@korea.ac.kr [Dept. of Display and Semiconductor Physics, Korea University, Chungnam (Korea, Republic of)

    2011-08-01

    A novel deposition process for nano-crystalline silicon (nc-Si) thin films was developed using neutral beam assisted chemical vapor deposition (NBaCVD) technology for the application of the thin film transistor (TFT) backplane of flexible active matrix organic light emitting diode (AMOLED). During the formation of a nc-Si thin film, the energetic particles enhance nano-sized crystalline rather microcrystalline Si in thin films. Neutral Particle Beam (NPB) affects the crystallinity in two ways: (1) NPB energy enhances nano-crystallinity through kinetic energy transfer and chemical annealing, and (2) heavier NPB (such as Ar) induces damage and amorphization through energetic particle impinging. Nc-Si thin film properties effectively can be changed by the reflector bias. As increase of NPB energy limits growing the crystalline, the performance of TFT supports this NPB behavior. The results of nc-Si TFT by NBaCVD demonstrate the technical potentials of neutral beam based processes for achieving high stability and reduced leakage in TFT backplanes for AMOLEDs.

  18. Inferring network flows from incomplete information with application to natural gas flows. [State-to-state natural gas flows in 1974-77

    Energy Technology Data Exchange (ETDEWEB)

    Hooker, J.N.

    1980-02-01

    A method is detailed for estimating flows along arcs (edges or links) of a network, such as a transportation network, when the total outflow and total inflow at each node (vertex) are known. It proves the optimality of a greedy method of choosing flows for independent estimation so as to determine the other flows, and does so by exploiting an underlying matroid structure. The resulting problem is formulated both as a linear program and a multi-commodity flow problem, and sensitivity analysis is performed. The technique is applied to the estimation of US state-to-state natural gas flows in the years 1974 to 1977, and numerical results are presented; 1974 and 1975 results are checked against actual data. The potential application of the same technique to the estimation of disaggregate data (of any kind), when aggregate and some disaggregate data are known, is pointed out.

  19. Application of the flow dimension concept for numerical drawdown data analyses in mixed-flow karst systems

    Science.gov (United States)

    Giese, M.; Reimann, T.; Liedl, R.; Maréchal, J.-C.; Sauter, M.

    2017-01-01

    A numerical discrete conduit-continuum model is employed to investigate large-scale groundwater abstraction in karst aquifers. The application of large-scale experiments is one approach to deal with the scale problem in hydraulic parameter assessment, caused by significant contrasts of hydraulic parameters in a karst aquifer. Here, conduit drawdown is evaluated by diagnostic plots and by considering the apparent flow dimension. These tools are frequently used for the interpretation of hydraulic borehole tests by analytical solutions. In contrast to existing analytical solutions, a numerical groundwater model allows the incorporation of the effect of complex parameter distributions. The objective is to demonstrate the application of diagnostic plots and flow dimension analysis for a systematic analysis of the effect of different boundary conditions as well as sink/source terms for idealized two-dimensional mixed karst aquifer systems, which ultimately extends existing analytical solutions and, therefore, contributes to the interpretation of measured field data. The analysis is focused on the apparent flow dimension and shows the extension of the cross-sectional flow area for selected models. The results are used to evaluate the large-scale pumping test of the karstified Cent Fonts catchment (Languedoc, France). The inverse calibration of two realistic, but still simplified, catchment models reveals that the apparent flow dimension supplies useful information about the general flow pattern during the Cent Fonts pumping test. The flow dimension after the end of the storage period can be explained by a large contribution of exchange flow resulting in a strong influence of radial flow on regional, i.e., kilometer scale.

  20. Flow coherent structures and frequency signature: application of the dynamic modes decomposition to open cavity flow

    Energy Technology Data Exchange (ETDEWEB)

    Lusseyran, F; Gueniat, F; Basley, J; Douay, C L; Pastur, L R; Faure, T M [LIMSI-CNRS BP 133, F-91403 Orsay Cedex (France); Schmid, P J [LadHyX, Ecole Polytechnique, F-91128 Palaiseau (France)

    2011-12-22

    The dynamic dimension of an impinging flow may be significantly reduced by its boundary conditions and self-sustained oscillations they induce. The spectral signature is associated with remarkable spatial coherent structures. Dynamic modes decomposition (DMD) makes it possible to directly extract the dynamical properties of a non-linearly saturated flow. We apply DMD to highlight the spectral contribution of the longitudinal and transverse structures of an experimental open-cavity flow.

  1. Application of the laser diode with central wavelength 975 nm for the therapy of neurofibroma and hemangiomas

    Science.gov (United States)

    Szymańczyk, Jacek; Sawczak, Mirosław; Cenian, Witold; Karpienko, Katarzyna; Jędrzejewska-Szczerska, Małgorzata; Cenian, Adam

    2017-01-01

    This paper presents a newly developed dermatological laser (with a central wavelength 975 nm) for application in therapies requiring deep penetration of tissue, e.g., cutaneous (dermal) neurofibroma (von Recklinghausen disease) and hemangiomas. This laser can work either in pulses or continues wave mode. Laser radiation is transmitted toward the application region by optical fiber with a diameter of 0.6 mm. The compact design of the laser facilitates its transport and increases the comfort of use.

  2. ORGANIC LIGHT EMITTING DIODE (OLED

    Directory of Open Access Journals (Sweden)

    Aririguzo Marvis Ijeaku

    2015-09-01

    Full Text Available An Organic Light Emitting Diode (OLED is a device composed of an organic layer that emits lights in response to an electrical current. Organic light emitting diodes have advanced tremendously over the past decades. The different manufacturing processes of the OLED itself to several advantages over flat panel displays made with LCD technology which includes its light weight and flexible plastic substrates, wider viewing angles, improved brightness, better power efficiency and quicker response time. However, its drawbacks include shorter life span, poor color balance, poor outdoor performance, susceptibility to water damage etc.The application of OLEDs in electronics is on the increase on daily basics from cameras to cell phones to OLED televisions, etc. Although OLEDs provides prospects for thinner, smarter, lighter and ultraflexible electronics displays, however, due to high cost of manufacturing, it is not yet widely used.

  3. Modeling three-dimensional flow about ellipsoidal inhomogeneities with application to flow to a gravel-packed well and flow through lens-shaped inhomogeneities

    Science.gov (United States)

    Fitts, Charles R.

    1991-05-01

    Analytic functions are superimposed to model three-dimensional steady groundwater flow in regions containing one or more Inhomogeneities shaped like prolate or oblate ellipsoids of revolution. Each function and the sum of such functions are solutions of Laplace's equation, the governing differential equation for steady groundwater flow. The functions are implemented in a manner that provides exact continuity of flow across the entire boundary of each inhomogeneity. In general, continuity of head is provided at specified control points on the boundary and is approximated between control points. For the case of one inhomogeneity in a uniform flow field, it turns out that there is exact continuity of head across the entire surface of the inhomogeneity. The method is implemented in a computer program written by the author. Two applications are demonstrated: (1) flow to a gravel-packed well and (2) flow through a series of lens-shaped inhomogeneities. The examples demonstrate that the approximation of continuity of head can be made acceptable for many problems. A possible application of the technique would be testing various theories regarding contaminant migration and dispersion by simulating flow and chemical diffusion through large numbers of lens-shaped inhomogeneities.

  4. Short-pulsed diode lasers as an excitation source for time-resolved fluorescence applications and confocal laser scanning microscopy in PDT

    Science.gov (United States)

    Kress, Matthias; Meier, Thomas H.; El-Tayeb, Tarek A. A.; Kemkemer, Ralf; Steiner, Rudolf W.; Rueck, Angelika C.

    2001-11-01

    This article describes a setup for subcellular time-resolved fluorescence spectroscopy and fluorescence lifetime measurements using a confocal laser scanning microscope in combination with a short pulsed diode laser for fluorescence excitation and specimen illumination. The diode laser emits pulses at 398 nm wavelength with 70 ps full width at half maximum (FWHM) duration. The diode laser can be run at a pulse repetition rate of 40 MHz down to single shot mode. For time resolved spectroscopy a spectrometer setup consisting of an Czerny Turner spectrometer and a MCP-gated and -intensified CCD camera was used. Subcellular fluorescence lifetime measurements were achieved using a time-correlated single photon counting (TCSPC) module instead of the spectrometer setup. The capability of the short pulsed diode laser for fluorescence imaging, fluorescence lifetime measurements and time-resolved spectroscopy in combination with laser scanning microscopy is demonstrated by fluorescence analysis of several photosensitizers on a single cell level.

  5. Large deviations for stochastic flows and their applications

    Institute of Scientific and Technical Information of China (English)

    高付清; 任佳刚

    2001-01-01

    Large deviations for stochastic flow solutions to SDEs containing a small parameter are studied. The obtained results are applied to establish a Cp, r-large deviation principle for stochastic flows and for solutions to anticipating SDEs. The recent results of Millet-Nualart-Sans and Yoshida are improved and refined.

  6. Investigation of co-flow jet flow control and its applications

    Science.gov (United States)

    Lefebvre, Alexis M.

    This thesis investigates the performance of co-flow jet (CFJ) flow control and its applications using experimental testing and computational fluid dynamics (CFD) simulations. For a stationary airfoil and wing, CFJ increases the lift coefficient (CL), reduces the drag and may produce thrust at a low angle of attack (AoA). The maximum lift coefficient is substantially increased for a 2D CFJ airfoil and reaches a value of 4.8 at Cmicro = 0.30. The power consumption of the CFJ pump, measured by the power coefficient (Pc), is influenced by a variety of parameters, including the momentum coefficient (C micro ), the AoA, the injection slot location, and the internal cavity configuration. A low Cmicro of 0.04 produces a rather small Pc in the range of 0.01--0.02 while a higher Cmicro rapidly increases the Pc. Due to the stronger leading edge suction effect, increasing the AoA decreases the Pc. That is until the flow is near separation, within about 2°--3° of the stall AoA. An injection slot location within 2%--5% chord from the leading edge very effectively reduces the power coefficient. An internal cavity design with no separation is crucial to minimize the CFJ power consumption. Overall, the CFJ effectiveness is enhanced with an increasing Mach number as long as the flow remains subsonic, typically with free stream Mach number less than 0.4. Two pitching airfoil oscillations with dynamic stall are studied in this thesis, namely the mild dynamic stall and the deep dynamic stall. At Mach 0.3, the CFJ with a relatively low Cmicro of 0.08 removes the mild dynamic stall. Thereby, the time-averaged lift is increased by 32% and the time-averaged drag is decreased by 80%. The resulting time-averaged aerodynamic (L/D)ave, which does not take the pumping power into account, reaches 118.3. When C micro is increased, the time-averaged drag becomes negative, which demonstrates the feasibility of a CFJ to propel helicopter blades using its pump as the only source of power. The deep

  7. Application of flow cytometry in marine phytoplankton research: current applications and future perspectives

    Directory of Open Access Journals (Sweden)

    Marcel J.W. Veldhuis

    2000-06-01

    Full Text Available A brief overview is given of current applications of flow cytometry (FCM in marine phytoplankton research. This paper presents a selection of highlights and various technical and analytical problems we encountered during the past 10 years. In particular, the conversion of the relative values obtained in terms of size and fluorescence applying FCM to quantitative estimates of cell size, pigment concentration, genome size etc., is addressed. The introduction of DNA -cell-cycle analysis made easily assessable by flow cytometry has been of great importance, allowing in situ measurement of species specific growth rates. Key questions in ecology such as factors determining the wax and wane of phytoplankton bloom can now be better answered in terms of species specific growth and mortality. Finally, flow cytometry provides detailed information of the physiological status of the individual algal cells. New staining methods enable us to distinguish between viable and non-viable cells and so will help us to elucidate the importance of automortality in aquatic ecosystems.

  8. Photovoltaic-module bypass-diode encapsulation. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    1983-06-20

    The design and processing techniques necessary to incorporate bypass diodes within the module encapsulant are presented in this annual report. A comprehensive survey of available pad-mounted PN junction and Schottky diodes led to the selection of Semicon PN junction diode cells for this application. Diode junction-to-heat spreader thermal resistance measurements, performed on a variety of mounted diode chip types and sizes, have yielded values which are consistently below 1/sup 0/C per watt, but show some instability when thermally cycled over the temperature range from -40 to 150/sup 0/C. Based on the results of a detailed thermal analysis, which covered the range of bypass currents from 2 to 20 amperes, three representative experimental modules, each incorporating integral bypass diode/heat spreader assemblies of various sizes, were designed and fabricated. Thermal testing of these modules has enabled the formation of a recommended heat spreader plate sizing relationship. The production cost of three encapsulated bypass diode/heat spreader assemblies were compared with similarly rated externally-mounted packaged diodes. An assessment of bypass diode reliability, which relies heavily on rectifying diode failure rate data, leads to the general conclusion that, when proper designed and installed, these devices will improve the overall reliability of a terrestrial array over a 20 year design lifetime.

  9. Application of the electrodiffusion method for near-wall flow diagnostics

    Directory of Open Access Journals (Sweden)

    Tihon J.

    2014-03-01

    Full Text Available The electrodiffusion method is presented as a measuring technique suitable for the flow measurement done in close proximity of the wall, thus in the region difficultly accessible by standard anemometric techniques (e.g. PIV, LDA. The experimental results obtained in different flow configurations (backward-facing step flow, wavy film flow, turbulent channel flow, rising Taylor bubbles document application capabilities of this technique, e.g. for mapping of wall shear stresses, delimitation of stable flow-recirculation zones, detection of short-time reversal of the near-wall flow, investigation of the near-wall turbulence, or detection of moving fluid particles. A new technology of sensor fabrication based on photolithography is introduced and possible applications of microsensors in microfluidic devices discussed.

  10. Extraction of Y2 O3 :Cr(3+) nanophosphor by eco-friendly approach and its suitability for white light-emitting diode applications.

    Science.gov (United States)

    Prasanna Kumar, J B; Ramgopal, G; Sunitha, D V; Prasad, B Daruka; Nagabhushana, H; Vidya, Y S; Anantharaju, K S; Prashantha, S C; Sharma, S C; Prabhakara, K R

    2017-05-01

    Cr(3)(+) -doped Y2 O3 (0.5-9 mol%) was synthesized by a simple solution combustion method using Aloe vera gel as a fuel/surfactant. The final obtained product was calcined at 750°C for 3 h, which is the lowest temperature reported so far for the synthesis of this compound. The calcined product was confirmed for its crystallinity and purity by powder X-ray diffraction (PXRD) studies which showed a single-phase nano cubic phosphor. The particles size estimated by Scherrer formula was in the range of 6-19 nm. The UV-vis spectra showed absorption bands at 198, 272 and 372 nm having band gap energy in the range 4.00-4.26 eV. In order to investigate the possibility of its use in white light emitting display applications, the photoluminescence properties of Cr(3)(+) -doped Y2 O3 nanophosphors were studied at an excitation wavelength in the near ultraviolet (UV) light region (361 nm). The emission spectra consisted of emission peaks in the blue ((4) F9/2  → (6) H15/2 ), orange ((4) F9/2  → (6) H13/2 ) and red ((4) F9/2  → (6) H11/2 ) regions. The CIE coordinates (0.33, 0.33) lie in the white light region. Hence Y2 O3 :Cr(3)(+) can be used for white light-emitting diode (LED) applications. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Construction of an X-ray detecting module and its application to relative-sensitivity measurement using a silicon PIN diode in conjunction with short-decay-time scintillators

    Science.gov (United States)

    Nihei, Shinichi; Sato, Eiichi; Hamaya, Tatsuki; Numahata, Wataru; Kogita, Hayato; Kami, Syouta; Arakawa, Yumeka; Oda, Yasuyuki; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya

    2014-12-01

    To detect low-dose-rate X-rays, we have developed an X-ray-detecting module for semiconductor diodes. The module consists of a current-voltage (I-V) amplifier, a voltage-voltage (V-V) amplifier, and an alternating-current adopter with a smoothing circuit. The photocurrents flowing through a diode are converted into voltages and amplified using the I-V and V-V amplifiers. To measure relative sensitivities, we used three silicon PIN diodes (Si-PIN), a cerium-doped yttrium aluminum perovskite [YAP(Ce)] crystal, and a Lu2(SiO4)O [LSO] crystal. Three detectors are as follows: an Si-PIN, a YAP(Ce)-Si-PIN, and an LSO-Si-PIN. Using the three detectors, the amplifier output voltages were in proportion to the tube current at a constant tube voltage of 70 kV. Using a multichannel analyzer, the event-pulse-height spectra were measured to analyze X-ray-electric conversion effect in the three detectors. The output voltage of the Si-PIN was approximately twice as high as those obtained using the YAP(Ce)-Si-PIN and the LSO-Si-PIN at the measurement conditions.

  12. Applications of URANS on predicting unsteady turbulent separated flows

    Institute of Scientific and Technical Information of China (English)

    Jinglei Xu; Huiyang Ma

    2009-01-01

    Accurate prediction of unsteady separated turbu-lent flows remains one of the toughest tasks and a practi-cal challenge for turbulence modeling. In this paper, a 2D flow past a circular cylinder at Reynolds number 3,900 is numerically investigated by using the technique of unsteady RANS (URANS). Some typical linear and nonlinear eddy viscosity turbulence models (LEVM and NLEVM) and a quadratic explicit algebraic stress model (EASM) are evalu-ated. Numerical results have shown that a high-performance cubic NLEVM, such as CLS, are superior to the others in simulating turbulent separated flows with unsteady vortex shedding.

  13. Applications of URANS on predicting unsteady turbulent separated flows

    Science.gov (United States)

    Xu, Jinglei; Ma, Huiyang

    2009-06-01

    Accurate prediction of unsteady separated turbulent flows remains one of the toughest tasks and a practical challenge for turbulence modeling. In this paper, a 2D flow past a circular cylinder at Reynolds number 3,900 is numerically investigated by using the technique of unsteady RANS (URANS). Some typical linear and nonlinear eddy viscosity turbulence models (LEVM and NLEVM) and a quadratic explicit algebraic stress model (EASM) are evaluated. Numerical results have shown that a high-performance cubic NLEVM, such as CLS, are superior to the others in simulating turbulent separated flows with unsteady vortex shedding.

  14. 4D Flow MRI in Neuroradiology: Techniques and Applications.

    Science.gov (United States)

    Pereira, Vitor Mendes; Delattre, Benedicte; Brina, Olivier; Bouillot, Pierre; Vargas, Maria Isabel

    2016-04-01

    Assessment of the intracranial flow is important for the understanding and management of cerebral vascular diseases. From brain aneurysms and arteriovenous malformations lesions to intracranial and cervical stenosis, the appraisal of the blood flow can be crucial and influence positively on patients' management. The determination of the intracranial hemodynamics and the collateral pattern seems to play to a major role in the management of these lesions. 4D flow magnetic resonance imaging is a noninvasive phase contrast derived method that has been developed and applied in neurovascular diseases. It has a great potential if followed by further technical improvements and comprehensive and systematic clinical studies.

  15. THEORY OF NONFLUIDIZED GAS SOLIDS FLOW AND ITS APPLICATION

    Institute of Scientific and Technical Information of China (English)

    Hongzhong Li

    2005-01-01

    A theory of nonfluidized gas-solids flow, which combines the theory of multiphase flow with the mechanics of particulate media, was proposed on the basis of understanding that the particles contact each other, solids and gas are in movement, and the drag force on the particles caused by interstitial gas flow is similar to gravity force having the property of mass force. Then this theory was verified by experiments on vertical and inclined moving beds, and was applied to calculation and design of equipment and devices with moving beds, such as pneumatic moving bed transport,dipleg, V-value, L-valve, orifice flow, and arching prevention. It can be used to guide the design and operation of moving beds and fixed beds.

  16. Application of Neutron Radiography to Flow Visualization in Supercritical Water

    Science.gov (United States)

    Takenaka, N.; Sugimoto, K.; Takami, S.; Sugioka, K.; Tsukada, T.; Adschiri, T.; Saito, Y.

    Supercritical water is used in various chemical reaction processes including hydrothermal synthesis of metal oxide nano-particles, oxidation, chemical conversion of biomass and plastics. Density of the super critical water is much less than that of the sub-critical water. By using neutron radiography, Peterson et al. have studied salt precipitation processes in supercritical water and the flow pattern in a reverse-flow vessel for salt precipitation, and Balasko et al. have revealed the behaviour of supercritical water in a container. The nano-particles were made by mixing the super critical flow and the sub critical water solution. In the present study, neutron radiography was applied to the flow visualization of the super and sub critical water mixture in a T-junction made of stainless steel pipes for high pressure and temperature conditions to investigate their mixing process. Still images by a CCD camera were obtained by using the neutron radiography system at B4 port in KUR.

  17. Application of microwave reflectometry to disordered petroleum multiphase flow study

    Science.gov (United States)

    Jannier, B.; Dubrunfaut, O.; Ossart, F.

    2013-02-01

    Microwave reflectometry is applied to multiphase flow metering in the context of oil extraction. Our sensor consists of two open-ended coaxial probes operating at complementary frequencies (at 600 MHz and around 36 GHz) and was designed to resist harsh field conditions. This paper presents and comments on results obtained in realistic dynamic conditions, on a triphasic flow loop (water-oil-gas). The main conclusions are the following: Bruggeman-Hanai's mixing rule applies to natural emulsions and can be used to determine the composition of the water-oil liquid phase; results obtained for annular flows are very sensitive to small perturbations such as bubbles or waves at the liquid-gas interface; in the case of triphasic slug flows, the composition of the liquid phase can be estimated by proper filtering of the data.

  18. Concave Generalized Flows with Applications to Market Equilibria

    CERN Document Server

    Vegh, Laszlo A

    2011-01-01

    We consider a nonlinear extension of the generalized network flow model, with the flow leaving an arc being an increasing concave function of the flow entering it, as proposed by Truemper and Shigeno. We give the first polynomial time combinatorial algorithm for solving corresponding optimization problems, finding a epsilon-approximate solution in O(m(m+\\log n)\\log(MUm/epsilon)) arithmetic operations and value oracle queries, where M and U are upper bounds on simple parameters. For (linear) generalized flows, our algorithm can be seen as a variant of the highest-gain augmenting path algorithm by Goldfarb, Jin and Orlin. We show that this general convex programming model serves as a common framework for several market equilibrium problems, including the linear Fisher market model and its various extensions. Our result immediately enables us to extend these market models to more general settings and to solve some open problems in the literature.

  19. Universally applicable three-dimensional hydrodynamic microfluidic flow focusing

    OpenAIRE

    Chiu, Yu-Jui; Cho, Sung Hwan; Mei, Zhe; Lien, Victor; Wu, Tsung-Feng; Lo, Yu-Hwa

    2013-01-01

    We have demonstrated a microfluidic device that can not only achieve three-dimensional flow focusing but also confine particles to the center stream along the channel. The device has a sample channel of smaller height and two sheath flow channels of greater height, merged into the downstream main channel where 3D focusing effects occur. We have demonstrated that both beads and cells in our device display significantly lower CVs in velocity and position distributions as well as reduced probabi...

  20. IMPATT diodes. Citations from the NTIS data base

    Science.gov (United States)

    Reed, W. E.

    1980-04-01

    Government sponsored research reports are cited covering the design, characterization, and applications of IMPATT diodes. Topics include reliability, power handling, properties, noise, fabrication, and radiation effects. The use of silicon and gallium arsenide IMPATT diodes for microwave generation and amplification is included. This updated bibliography contains 182 abstracts, 14 of which are new entries to the previous edition.

  1. Application of Lattice Boltzmann Method to Flows in Microgeometries

    Directory of Open Access Journals (Sweden)

    Anoop K. Dass

    2010-07-01

    Full Text Available In the present investigation, Lattice Boltzmann Method (LBM is used to simulate rarefied gaseous microflows in three microgeometries. These are micro-couette, micro lid-driven cavity and micro-poiseuille flows. The Knudsen number is used to measure the degree of rarefaction in the microflows. First, micro-couette flow is computed with the effects of varying Knudsen number in the slip and threshold of the transition regime and the results compare well with existing results. After having thus established the credibility of the code and the method including boundary conditions, LBM is then used to investigate the micro lid-driven cavity flow with various aspect ratios. Simulation of microflow not only requires an appropriate method, it also requires suitable boundary conditions to provide a well-posed problem and unique solution. In this work, LBM and three slip boundary conditions, namely, diffuse scattering boundary condition, specular reflection and a combination of bounce-back and specular reflection is used to predict the micro lid-driven cavity flow fields. Then the LBM simulation is extended to micro-poiseuille flow. The results are substantiated through comparison with existing results and it is felt that the present methodology is reasonable to be employed in analyzing the flow in micro-systems.

  2. A μ-biomimetic flow sensor for medical and pharmaceutical applications.

    Science.gov (United States)

    Stepniak, Simon; Bleckmann, Horst; Herzog, Hendrik; Klein, Adrian; Schulze, Elisabeth; Taetzner, Simon; Steltenkamp, Siegfried

    2015-08-01

    Flow sensing is pivotal in many medical and pharmaceutical applications. Most commercial flow sensors are either expensive, complex, or consume a lot of energy, while low cost sensors usually lack sensitivity, robustness, or long-term stability. In addition, the maintenance and sterilization of most commercial flow sensors is difficult to perform. Here, we present a new μ-biomimetic flow sensor based on the fish lateral line. It measures flow velocity and detects the transition between laminar and turbulent flow, thereby fulfilling most requirements for medical and pharmaceutical applications. Additionally, it has a modular setup featuring a screened or passive bypass configuration, enabling it not only to meter flow in medical applications but also under harsh or well-defined environmental conditions, such as found in pharmaceutical applications. The sensor is robust and can be easily cleaned. Individual parts of the sensor can even be replaced or sterilized. In sum, this sensor opens up a whole new field of applications in the area of medical and pharmaceutical related flow monitoring.

  3. Application guide for AFINCH (Analysis of Flows in Networks of Channels) described by NHDPlus

    Science.gov (United States)

    Holtschlag, David J.

    2009-01-01

    AFINCH (Analysis of Flows in Networks of CHannels) is a computer application that can be used to generate a time series of monthly flows at stream segments (flowlines) and water yields for catchments defined in the National Hydrography Dataset Plus (NHDPlus) value-added attribute system. AFINCH provides a basis for integrating monthly flow data from streamgages, water-use data, monthly climatic data, and land-cover characteristics to estimate natural monthly water yields from catchments by user-defined regression equations. Images of monthly water yields for active streamgages are generated in AFINCH and provide a basis for detecting anomalies in water yields, which may be associated with undocumented flow diversions or augmentations. Water yields are multiplied by the drainage areas of the corresponding catchments to estimate monthly flows. Flows from catchments are accumulated downstream through the streamflow network described by the stream segments. For stream segments where streamgages are active, ratios of measured to accumulated flows are computed. These ratios are applied to upstream water yields to proportionally adjust estimated flows to match measured flows. Flow is conserved through the NHDPlus network. A time series of monthly flows can be generated for stream segments that average about 1-mile long, or monthly water yields from catchments that average about 1 square mile. Estimated monthly flows can be displayed within AFINCH, examined for nonstationarity, and tested for monotonic trends. Monthly flows also can be used to estimate flow-duration characteristics at stream segments. AFINCH generates output files of monthly flows and water yields that are compatible with ArcMap, a geographical information system analysis and display environment. Chloropleth maps of monthly water yield and flow can be generated and analyzed within ArcMap by joining NHDPlus data structures with AFINCH output. Matlab code for the AFINCH application is presented.

  4. Frequency-comb-assisted broadband precision spectroscopy with cascaded diode lasers

    DEFF Research Database (Denmark)

    Liu, Junqiu; Brasch, Victor; Pfeiffer, Martin H. P.;

    2016-01-01

    Frequency-comb-assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this Letter, we present a novel method using cascaded frequency agile diode lasers...

  5. Analytical application of 2f-wavelength modulation for isotope selective diode laser graphite furnace atomic absorption spectroscopy.

    Science.gov (United States)

    Wizemann, H D

    2000-01-01

    Experiences in the analytical application of the 2f-wavelength modulation technique for isotope selective atomic absorption spectroscopy in a graphite furnace are reported. Experimental as well as calculated results are presented, mainly for the natural lithium isotopes. Sensitivity, linearity, and (isotope) selectivity are studied by intensity modulation and wavelength modulation. High selectivities can be attained, however, on the cost of detection power. It is shown that the method enables the measurement of lithium isotope ratios larger than 2000 by absorption in a low-pressure graphite tube atomizer.

  6. Powerful infrared emitting diodes

    Directory of Open Access Journals (Sweden)

    Kogan L. M.

    2012-02-01

    Full Text Available Powerful infrared LEDs with emission wavelength 805 ± 10, 870 ± 20 and 940 ± 10 nm developed at SPC OED "OPTEL" are presented in the article. The radiant intensity of beam diode is under 4 W/sr in the continuous mode and under 100 W/sr in the pulse mode. The radiation power of wide-angle LEDs reaches 1 W in continuous mode. The external quantum efficiency of emission IR diodes runs up to 30%. There also has been created infrared diode modules with a block of flat Fresnel lenses with radiant intensity under 70 W/sr.

  7. CIME course on Ricci Flow and Geometric Applications

    CERN Document Server

    Mantegazza, Carlo

    2016-01-01

    Presenting some impressive recent achievements in differential geometry and topology, this volume focuses on results obtained using techniques based on Ricci flow. These ideas are at the core of the study of differentiable manifolds. Several very important open problems and conjectures come from this area and the techniques described herein are used to face and solve some of them. The book's four chapters are based on lectures given by leading researchers in the field of geometric analysis and low-dimensional geometry/topology, respectively offering an introduction to: the differentiable sphere theorem (G. Besson), the geometrization of 3-manifolds (M. Boileau), the singularities of 3-dimensional Ricci flows (C. Sinestrari), and Kahler-Ricci flow (G. Tian). The lectures will be particularly valuable to young researchers interested in differential manifolds.

  8. Characterization of digital textile printing and polymer blend (PFO-DMP:P3HT) for application in manufacture of organic diodes emitting white light - WOLEDS

    Science.gov (United States)

    da Silva, Marco A. T.; Thomazini, Emanuelle F.; Albertini, Madson; Renzi, Wesley; Franchello, Flavio; Dias, Ivan F. L.; Duarte, José Leonil; Poças, Luiz C.; Lourenço, Sidney A.

    2016-12-01

    The research of materials and structures for the manufacture of organic diodes emitting white light WOLEDS has been very intense nowadays mainly due to the possibilities of its use in obtaining low-energy light consuming. The energy transfer between polymer materials has proven to be a great allied to search organic devices with emitting white light. Polymers such as PFO-DMP (donor) and P3HT (acceptor) are candidates for this application. In this work, P3HT, PFO-DMP and blends (PFO-DMP:P3HT (5%)) films were deposited by spin-coating on digital textile printing substrates. The optical properties of the digital textile printing, polymers and blend were studied by UV-VIS, steady-state photoluminescence (PL), PL quantum yield (PLQY) and Raman (all at 298 K) spectroscopy techniques. The digital textile printing were acquired from Isoliner, a Brazilian company specialized in this kind of textile. In the blend a strongly energy transfer from PFO-DMP to P3HT was observed. The PL spectrum of the PFO-DMP:P3HT (5%) covers the 430-730 nm range. From integrated PL spectra in the range of 13-643 K, it was obtained the temperature at which the phosphor loses 50% of its initial emission intensity, T1/2 = 430 K. Gaussian fits were performed, and the peaks were identified. Raman measurements were performed on substrates with and without polymers deposited and the results are in agreement with those found in the literature. Vibrational modes of textile increase the full width half maximum (FWHM), due to electron-phonons interaction. Results obtained through the coordinate calculation CIE from blend emission for various types of textile digital printing tested, showed the more appropriate combinations (substrate/blend) for emission in white.

  9. Two Phase Flow and Space-Based Applications

    Science.gov (United States)

    McQuillen, John

    1999-01-01

    A reduced gravity environment offers the ability to remove the effect of buoyancy on two phase flows whereby density differences that normally would promote relative velocities between the phases and also alter the shape of the interface are removed. However, besides being a potent research tool, there are also many space-based technologies that will either utilize or encounter two-phase flow behavior, and as a consequence, several questions must be addressed. This paper presents some of these technologies missions. Finally, this paper gives a description of web-sites for some funding.

  10. Development of a FBG vortex flow sensor for high-temperature applications

    NARCIS (Netherlands)

    Cheng, L.K.; Schiferli, W.; Nieuwland, R.A.; Franzen, A.; Boer, J.J. den; Jansen, T.H.

    2011-01-01

    A robust fibre optic flow sensor has been developed to measure liquid or gas flows at ambient temperatures up to 300°C and pressures up to 100 bar. While such environmental conditions are typical in pressurized steam systems in the oil and gas industry (downhole and surface), wider applications are

  11. Application of a chimera technique to the computation of subsonic and transonic bi-airfoil flows

    NARCIS (Netherlands)

    L.C.Q. Yagua; B. Koren (Barry)

    2004-01-01

    textabstractThis paper describes the application of a composite overset-grid technique to flow computations around a two-dimensional bi-plane. The flow is described by the steady, 2D, compressible Euler equations of gas dynamics. The discretization method used is a central finite-difference method

  12. Active Flow Control on Bidirectional Rotors for Tidal MHK Applications

    Energy Technology Data Exchange (ETDEWEB)

    Shiu, Henry [Research Engineer; van Dam, Cornelis P. [Professor

    2013-08-22

    A marine and hydrokinetic (MHK) tidal turbine extracts energy from tidal currents, providing clean, sustainable electricity generation. In general, all MHK conversion technologies are confronted with significant operational hurdles, resulting in both increased capital and operations and maintenance (O&M) costs. To counter these high costs while maintaining reliability, MHK turbine designs can be simplified. Prior study found that a tidal turbine could be cost-effectively simplified by removing blade pitch and rotor/nacelle yaw. Its rotor would run in one direction during ebb and then reverse direction when the current switched to flood. We dubbed such a turbine a bidirectional rotor tidal turbine (BRTT). The bidirectional hydrofoils of a BRTT are less efficient than conventional hydrofoils and capture less energy, but the elimination of the pitch and yaw systems were estimated to reduce levelized cost of energy by 7.8%-9.6%. In this study, we investigated two mechanisms for recapturing some of the performance shortfall of the BRTT. First, we developed a novel set of hydrofoils, designated the yy series, for BRTT application. Second, we investigated the use of active flow control via microtabs. Microtabs are small deployable/retractable tabs, typically located near the leading or trailing edge of an air/hydrofoil with height on the order of the boundary layer thickness (1% - 2% of chord). They deploy approximately perpendicularly to the foil surface and, like gurney flaps and plain flaps, globally affect the aerodynamics of the airfoil. By strategically placing microtabs and selectively deploying them based on the direction of the inflow, performance of a BRTT rotor can be improved while retaining bidirectional operation. The yy foils were computationally designed and analyzed. They exhibited better performance than the baseline bidirectional foil, the ellipse. For example, the yyb07cn-180 had 14.7% higher (l/d)max than an ellipse of equal thickness. The yyb07cn

  13. Modeling and characterization of double resonant tunneling diodes for application as energy selective contacts in hot carrier solar cells

    Science.gov (United States)

    Jehl, Zacharie; Suchet, Daniel; Julian, Anatole; Bernard, Cyril; Miyashita, Naoya; Gibelli, Francois; Okada, Yoshitaka; Guillemolles, Jean-Francois

    2017-02-01

    Double resonant tunneling barriers are considered for an application as energy selective contacts in hot carrier solar cells. Experimental symmetric and asymmetric double resonant tunneling barriers are realized by molecular beam epitaxy and characterized by temperature dependent current-voltage measurements. The negative differential resistance signal is enhanced for asymmetric heterostructures, and remains unchanged between low- and room-temperatures. Within Tsu-Esaki description of the tunnel current, this observation can be explained by the voltage dependence of the tunnel transmission amplitude, which presents a resonance under finite bias for asymmetric structures. This effect is notably discussed with respect to series resistance. Different parameters related to the electronic transmission of the structure and the influence of these parameters on the current voltage characteristic are investigated, bringing insights on critical processes to optimize in double resonant tunneling barriers applied to hot carrier solar cells.

  14. Computer Mapping of Pyroclastic Flow Inundation Probability: Application to the August 2006 Flows at Tungurahua, Ecuador

    Science.gov (United States)

    Sheridan, M. F.; Patra, A.; Dalbey, K.; Stinton, A.; Hall, M.

    2007-05-01

    In the summer of 2006 Tungurahua produced its most intense pyroclastic activity since the current eruptive cycle began in October 1999. In mid-July and again in mid-August more than 20 pyroclastic flows descended ravines on the north to west flanks of the volcano causing at least five deaths and destroying property and livestock. These PFs reached the Chambo River at the base of the volcano and temporarily dammed it. The flows passed over the major Ambato-Baños highway and came within 2.5 km from the popular El Salado hot springs near the town of Banos (ca. 20,000 inhabitants). These August 16 pyroclastic flows provide a good data base for calibrating models used in hazard mapping. Titan2D is a computational code for volcanic block and ash flows and rock avalanches of various types and scales. It forms the core of the new Titan environment for volcanic hazards analysis that can integrate modeling, high-performance computing, database management, visualization, and collaborative environments to a very sophisticated level. Titan provides a solution to mapping problems by providing a probabilistic calculation of inundation depth that takes into account many of the critical uncertainties using a PCQ methodology to reduce computation time. We used TITAN to map potential inundation areas for future block-and-ash flows at Tungurahua, Ecuador. First the DEM was modified to fill the crater with a tiled plane to avoid back filling of the simulated flows. For each PCQ analysis we started with a 360° uniform distribution of initial direction of flow, a flux footprint with a 50 m radius and an initial velocity of velocity of 50 m s-1. Flux rates started at their maximum value and decreased linearly to zero over time; flux durations ranged between 1 and 5 minutes with duration being linear in volume. Then we used a flux footprint with a 50 m radius and an initial velocity of velocity of 50 m s-1. Flux rates started from their maximum value and decreased linearly to zero over

  15. A continuum theory for two-phase flows of particulate solids: application to Poiseuille flows

    Science.gov (United States)

    Monsorno, Davide; Varsakelis, Christos; Papalexandris, Miltiadis V.

    2015-11-01

    In the first part of this talk, we present a novel two-phase continuum model for incompressible fluid-saturated granular flows. The model accounts for both compaction and shear-induced dilatancy and accommodates correlations for the granular rheology in a thermodynamically consistent way. In the second part of this talk, we exercise this two-phase model in the numerical simulation of a fully-developed Poiseuille flow of a dense suspension. The numerical predictions are shown to compare favorably against experimental measurements and confirm that the model can capture the important characteristics of the flow field, such as segregation and formation of plug zones. Finally, results from parametric studies with respect to the initial concentration, the magnitude of the external forcing and the width of the channel are presented and the role of these physical parameters is quantified. Financial Support has been provided by SEDITRANS, an Initial Training Network of the European Commission's 7th Framework Programme

  16. Application of Gaussian beam ray-equivalent model and back-propagation artificial neural network in laser diode fast axis collimator assembly.

    Science.gov (United States)

    Yu, Hao; Rossi, Giammarco; Braglia, Andrea; Perrone, Guido

    2016-08-10

    The paper presents the development of a tool based on a back-propagation artificial neural network to assist in the accurate positioning of the lenses used to collimate the beam from semiconductor laser diodes along the so-called fast axis. After training using a Gaussian beam ray-equivalent model, the network is capable of indicating the tilt, decenter, and defocus of such lenses from the measured field distribution, so the operator can determine the errors with respect to the actual lens position and optimize the diode assembly procedure. An experimental validation using a typical configuration exploited in multi-emitter diode module assembly and fast axis collimating lenses with different focal lengths and numerical apertures is reported.

  17. Contactless Impedance Sensors and Their Application to Flow Measurements

    Directory of Open Access Journals (Sweden)

    Karel Štulík

    2013-02-01

    Full Text Available The paper provides a critical discussion of the present state of the theory of high-frequency impedance sensors (now mostly called contactless impedance or conductivity sensors, the principal approaches employed in designing impedance flow-through cells and their operational parameters. In addition to characterization of traditional types of impedance sensors, the article is concerned with the use of less common sensors, such as cells with wire electrodes or planar cells. There is a detailed discussion of the effect of the individual operational parameters (width and shape of the electrodes, detection gap, frequency and amplitude of the input signal on the response of the detector. The most important problems to be resolved in coupling these devices with flow-through measurements in the liquid phase are also discussed. Examples are given of cell designs for continuous flow and flow-injection analyses and of detection systems for miniaturized liquid chromatography and capillary electrophoresis. New directions for the use of these sensors in molecular biology and chemical reactors and some directions for future development are outlined.

  18. Microfluidic energy conversion by application of two phase flow

    NARCIS (Netherlands)

    Xie, Yanbo

    2013-01-01

    The classical electrokinetic energy conversion mechanism relies on a single stage conversion by forcing liquid through a channel with charged walls. When the net charges inside the electrical double layer (EDL) are transported by water flow, the produced electrical energy can be harvested via connec

  19. Synthesis of electroactive ionic liquids for flow battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Travis Mark; Ingersoll, David; Staiger, Chad; Pratt, Harry

    2015-09-01

    The present disclosure is directed to synthesizing metal ionic liquids with transition metal coordination cations, where such metal ionic liquids can be used in a flow battery. A cation of a metal ionic liquid includes a transition metal and a ligand coordinated to the transition metal.

  20. Contactless impedance sensors and their application to flow measurements.

    Science.gov (United States)

    Opekar, František; Tůma, Petr; Stulík, Karel

    2013-02-27

    The paper provides a critical discussion of the present state of the theory of high-frequency impedance sensors (now mostly called contactless impedance or conductivity sensors), the principal approaches employed in designing impedance flow-through cells and their operational parameters. In addition to characterization of traditional types of impedance sensors, the article is concerned with the use of less common sensors, such as cells with wire electrodes or planar cells. There is a detailed discussion of the effect of the individual operational parameters (width and shape of the electrodes, detection gap, frequency and amplitude of the input signal) on the response of the detector. The most important problems to be resolved in coupling these devices with flow-through measurements in the liquid phase are also discussed. Examples are given of cell designs for continuous flow and flow-injection analyses and of detection systems for miniaturized liquid chromatography and capillary electrophoresis. New directions for the use of these sensors in molecular biology and chemical reactors and some directions for future development are outlined.

  1. Fluorometric flow-immunoassay for alkylphenol polyethoxylates on a microchip containing a fluorescence detector comprised of an organic light emitting diode and an organic photodiode.

    Science.gov (United States)

    Liu, Rong; Ishimatsu, Ryoichi; Yahiro, Masayuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko

    2015-03-01

    A compact fluorescence detector was constructed on a microchip from an organic light emitting diode (OLED) as the light source and an organic photodiode (OPD) as the photo-detector and was used in an immunoassay for alkylphenol polyethoxylates (APE). The OLED based on a terbium complex emitted a sharp light at the main wavelength of 546 nm with a full width at half maximum of 9 nm. The incident photo-to-current conversion efficiency (IPCE) of the OPD fabricated with Fullerene 70 (C70) and tris[4-(5-phenylthiopen-2-yl)phenyl]-amine (TPTPA) was approximately 44% for light at a wavelength of 586 nm. The performance of the fluorescence detector was evaluated for the determination of resorufin (λ(em)=586 nm) and the photocurrent of the OPD due to the fluorescence of resorufin was proportional to the concentration of resorufin in the range from 0 to 18 µM with a detection limit (S/N=3) of 0.6 µM. The fluorescence detector was successfully utilized in a competitive enzyme-linked immunosorbent assay for APE, where an anti-APE antibody was immobilized on the surface of the channel of the Polydimethylsiloxane (PDMS) microchip or on the surface of magnetic microbeads. After an immunoreaction with a sample solution of APE containing a horse radish peroxidase (HRP)-labeled APE, the fluorescence of resorufin generated just after introduction of a mixed solution of Amplex Red and H2O2 was measured using the fluorescence detector. The calibration curve for the photocurrent signals of the OPD due to the fluorescence of resorufin against the logarithmic concentration of APE was sigmoidal in shape. The detection limits defined as IC80 were ca. 1 ppb and ca. 2 ppb, respectively, for the methods using the anti-APE antibody immobilized on the surface of the microchannel and in the case where the antibody was immobilized on the surface of magnetic microbeads. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Chemically Modulated Graphene Diodes

    OpenAIRE

    Kim, Hye-young; Lee, Kangho; McEvoy, Niall; Yim, Chanyoung; Duesberg, Georg S.

    2013-01-01

    PUBLISHED We report the manufacture of novel graphene diode sensors (GDS), which are composed of monolayer graphene on silicon substrates, allowing exposure to liquids and gases. Parameter changes in the diode can be correlated with charge transfer from various adsorbates. The GDS allows for investigation and tuning of extrinsic doping of graphene with great reliability. The demonstrated recovery and long-term stability qualifies the GDS as a new platform for gas, environmental, and biocom...

  3. Extracting directed information flow networks: an application to genetics and semantics

    CERN Document Server

    Masucci, A P; Hernández-García, E; Kalampokis, A

    2010-01-01

    We introduce a general method to infer the directional information flow between populations whose elements are described by n-dimensional vectors of symbolic attributes. The method is based on the Jensen-Shannon divergence and on the Shannon entropy and has a wide range of application. We show here the results of two applications: first extracting the network of genetic flow between the meadows of the seagrass Poseidonia Oceanica, where the meadow elements are specified by sets of microsatellite markers, then we extract the semantic flow network from a set of Wikipedia pages, showing the semantic channels between different areas of knowledge.

  4. Study of the collector/heat pipe cooled externally configured thermionic diode

    Science.gov (United States)

    1973-01-01

    A collector/heat pipe cooled, externally configured (heated) thermionic diode module was designed for use in a laboratory test to demonstrate the applicability of this concept as the fuel element/converter module of an in-core thermionic electric power source. During the course of the program, this module evolved from a simple experimental mock-up into an advanced unit which was more reactor prototypical. Detailed analysis of all diode components led to their engineering design, fabrication, and assembly, with the exception of the collector/heat pipe. While several designs of high power annular wicked heat pipes were fabricated and tested, each exhibited unexpected performance difficulties. It was concluded that the basic cause of these problems was the formation of crud which interfered with the liquid flow in the annular passage of the evaporator region.

  5. Numerical simulation methods of incompressible flows and an application to the Space Shuttle main engine

    Science.gov (United States)

    Chang, J. L. C.; Kwak, D.; Rogers, S. E.; Yang, R.-J.

    1988-01-01

    This paper discusses incompressible Navier-Stokes solution methods with an emphasis on the pseudocompressibility method. A steady-state flow solver based on the pseudocompressibility approach is then described. This flow solver code has been used to analyze the internal flow in the Space Shuttle main engine hot-gas manifold. Salient features associated with this three-dimensional realistic flow simulation are discussed. Numerical solutions relevant to the current engine analysis and the redesign effort are discussed along with experimental results. This example demonstrates the potential of computational fluid dynamics as a design tool for aerospace applications.

  6. Advances in transitional flow modeling applications to helicopter rotors

    CERN Document Server

    Sheng, Chunhua

    2017-01-01

    This book provides a comprehensive description of numerical methods and validation processes for predicting transitional flows based on the Langtry–Menter local correlation-based transition model, integrated with both one-equation Spalart–Allmaras (S–A) and two-equation Shear Stress Transport (SST) turbulence models. A comparative study is presented to combine the respective merits of the two coupling methods in the context of predicting the boundary-layer transition phenomenon from fundamental benchmark flows to realistic helicopter rotors. The book will of interest to industrial practitioners working in aerodynamic design and the analysis of fixed-wing or rotary wing aircraft, while also offering advanced reading material for graduate students in the research areas of Computational Fluid Dynamics (CFD), turbulence modeling and related fields.

  7. APPLICATION OF THE THEORY OF INTERACTING CONTINUA TO BLOOD FLOW

    Energy Technology Data Exchange (ETDEWEB)

    Massoudi, Mehrdad; Kim, Jeongho; Hund, Samuel J.; Antaki, James F.

    2011-01-01

    Micro-scale investigations of the flow and deformation of blood and its formed elements have been studied for many years. Early in vitro investigations in the rotational viscometers or small glass tubes revealed important rheological properties such as the reduced blood apparent viscosity, Fahraeus effect and Fahraeus-Lindqvist effect [1], exhibiting the nonhomogeneous property of blood in microcirculation. We have applied Mixture Theory, also known as Theory of Interacting Continua, to study and model this property of blood [2, 3]. This approach holds great promise for predicting the trafficking of RBCs in micro-scale flows (such as the depletion layer near the wall), and other unique hemorheological phenomena relevant to blood trauma. The blood is assumed to be composed of an RBC component modeled as a nonlinear fluid, suspended in plasma, modeled as a linearly viscous fluid.

  8. Application of digital holography to circle flow bed boiler measurement

    Institute of Scientific and Technical Information of China (English)

    PU Shiliang; Denis Lebrun; WANG Qinghui; CEN Kefa; REN Kuanfang

    2007-01-01

    The spatial distribution of particles in the boiler is very important in the study on the circle flow bed boiler (CFB). Digital in-line holography technique was applied to obtain the spatial and diameter distribution of the particles inside the boiler. A HE-NE laser was used to illuminate the particles inside the CFB through two glass windows and the in-line diffraction pattern was recorded by a CCD camera. The diffraction can be interpreted as a convolution between a family of wavelet functions and the object function. So the three-dimensional (3D) images of the particles in the two-phase flow were reconstructed by the convolution between diffraction pattern and wavelet functions. The particle diameters and 3D coordinates were calculated from the reconstructed 3D images by a series of image-processing methods, followed by a discussion of the experimental results.

  9. Application of Active Flow Control Technique for Gust Load Alleviation

    Institute of Scientific and Technical Information of China (English)

    XU Xiaoping; ZHU Xiaoping; ZHOU Zhou; FAN Ruijun

    2011-01-01

    A new gust load alleviation technique is presented in this paper based on active flow control.Numerical studies are conducted to investigate the beneficial effects on the aerodynamic characteristics of the quasi “Global Hawk” airfoil using arrays of jets during the gust process.Based on unsteady Navier-Stokes equations,the grid-velocity method is introduced to simulate the gust influence,and dynamic response in vertical gust flow perturbation is investigated for the airfoil as well.An unsteady surface transpiration boundary condition is enforced over a user specified portion of the airfoil's surface to emulate the time dependent velocity boundary conditions.Firstly,after applying this method to simulate typical NACA0006 airfoil gust response to a step change in the angle of attack,it shows that the indicial responses of the airfoil make good agreement with the exact theoretical values and the calculated values in references.Furthermore,gust response characteristic for the quasi “Global Hawk” airfoil is analyzed.Five kinds of flow control techniques are introduced as steady blowing,steady suction,unsteady blowing,unsteady suction and synthetic jets.The physical analysis of the influence on the effects of gust load alleviation is proposed to provide some guidelines for practice.Numerical results have indicated that active flow control technique,as a new technology of gust load alleviation,can affect and suppress the fluid disturbances caused by gust so as to achieve the purpose of gust load alleviation.

  10. Ultrasonic analyte concentration and application in flow cytometry

    Energy Technology Data Exchange (ETDEWEB)

    Kaduchak, Gregory; Goddard, Greg; Salzman, Gary; Sinha, Dipen; Martin, John C.; Kwiatkowski, Christopher; Graves, Steven

    2015-07-07

    The present invention includes an apparatus and corresponding method for concentrating analytes within a fluid flowing through a tube using acoustic radiation pressure. The apparatus includes a function generator that outputs a radio frequency electrical signal to a transducer that transforms the radio frequency electric signal to an acoustic signal and couples the acoustic signal to the tube. The acoustic signal is converted within the tube to acoustic pressure that concentrates the analytes within the fluid.

  11. Ultrasonic analyte concentration and application in flow cytometry

    Energy Technology Data Exchange (ETDEWEB)

    Kaduchak, Gregory; Goddard, Greg; Salzman, Gary; Sinha, Dipen; Martin, John C.; Kwiatkowski, Christopher; Graves, Steven

    2014-07-22

    The present invention includes an apparatus and corresponding method for concentrating analytes within a fluid flowing through a tube using acoustic radiation pressure. The apparatus includes a function generator that outputs a radio frequency electrical signal to a transducer that transforms the radio frequency electric signal to an acoustic signal and couples the acoustic signal to the tube. The acoustic signal is converted within the tube to acoustic pressure that concentrates the analytes within the fluid.

  12. Turbulence in Internal Flows. Turbomachinery and Other Applications

    Science.gov (United States)

    1977-05-01

    fundamental time scale made a quantum jump of a factor of 4 which may be interpreted as indicating that on the average two amalgamations take place...only neces- sary to model the energy redistribution and dissipation terms (So, 1975). Recently, Peskin and So (1976) have examined the importance of...33421 VELOCITY SCALES FOR SWIRLING FLOWS 367 is gratefully acknowledged. The author also wishes to thank Pro- fessor R. L. Peskin , Director

  13. Ultrasonic analyte concentration and application in flow cytometry

    Science.gov (United States)

    Kaduchak, Gregory; Goddard, Greg; Salzman, Gary; Sinha, Dipen; Martin, John C.; Kwiatkowski, Christopher; Graves, Steven

    2008-03-11

    The present invention includes an apparatus and corresponding method for concentrating analytes within a fluid flowing through a tube using acoustic radiation pressure. The apparatus includes a function generator that outputs a radio frequency electrical signal to a transducer that transforms the radio frequency electric signal to an acoustic signal and couples the acoustic signal to the tube. The acoustic signal is converted within the tube to acoustic pressure that concentrates the analytes within the fluid.

  14. Application of double-layered skin phantoms for optical flow imaging during laser tattoo treatments

    Science.gov (United States)

    Lee, Byeong-il; Song, Woosub; Kim, Hyejin; Kang, Hyun Wook

    2016-05-01

    The feasible application of double-layered skin phantoms was evaluated to identify artificial blood flow with a Doppler optical coherence tomography (DOCT) system for laser tattoo treatments. Polydimethylsiloxane (PDMS) was used to fabricate the artificial phantoms with flow channels embedded. A double-integrating sphere system with an inverse adding-doubling method quantified both the absorption and the reduced scattering coefficients for epidermis and dermis phantoms. Both OCT and caliper measurements confirmed the double-layered phantom structure (epidermis = 136 ± 17 µm vs. dermis = 3.0 ± 0.1 mm). The DOCT method demonstrated that high flow rates were associated with high image contrast, visualizing the position and the shape of the flow channel. Application of the channel-embedded skin phantoms in conjunction with DOCT can be a reliable technique to assess dynamic variations in the blood flow during and after laser tattoo treatments.

  15. Review of zero-net-mass-flux jet and its application in separation flow control

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Since the zero-net-mass-flux (ZNMF) jet was first used as a laboratory flow control method in 1990’s, it has attracted much attention. The ZNMF jet has unique features such as compact actuator, no requirement for external air supply, complex piping, etc., and becomes a hot topic research subject in fluid mechanics. This review introduces the state of the art in the development of ZNMF jet in the quiescent fluid, the interaction of the ZNMF jet with the cross flow and its application in the separation flow control. The evolution of the vortex ring/pair and the spacial flow structure of the ZNMF in quicent fluid or cross flow are presented, as well as the key parameter effects. At last, the applications of ZNMF jet in the wake control of the circular cylinder, the separation control on the airfoil and the aerodynamic force or moment control on MAV/UAV are presented.

  16. Review of zero-net-mass-flux jet and its application in separation flow control

    Institute of Scientific and Technical Information of China (English)

    ZHANG PanFeng; WANG JinJun; FENG LiHao

    2008-01-01

    Since the zero-net-mass-flux (ZNMF) jet was first used as a laboratory flow control method in 1990's, it has attracted much attention. The ZNMF jet has unique features such as compact actuator, no requirement for external air supply, complex piping, etc., and becomes a hot topic research subject in fluid mechanics. This review introduces the state of the art in the development of ZNMF jet in the quiescent fluid, the interaction of the ZNMF jet with the cross flow and its application in the separation flow control. The evolution of the vortex ring/pair and the spacial flow structure of the ZNMF in quicent fluid or cross flow are presented, as well as the key parameter effects. At last, the applications of ZNMF jet in the wake control of the circular cylinder, the separation control on the airfoil and the aerodynamic force or moment control on MAV/UAV are presented.

  17. Heat transfer and fluid flow in biological processes advances and applications

    CERN Document Server

    Becker, Sid

    2015-01-01

    Heat Transfer and Fluid Flow in Biological Processes covers emerging areas in fluid flow and heat transfer relevant to biosystems and medical technology. This book uses an interdisciplinary approach to provide a comprehensive prospective on biofluid mechanics and heat transfer advances and includes reviews of the most recent methods in modeling of flows in biological media, such as CFD. Written by internationally recognized researchers in the field, each chapter provides a strong introductory section that is useful to both readers currently in the field and readers interested in learning more about these areas. Heat Transfer and Fluid Flow in Biological Processes is an indispensable reference for professors, graduate students, professionals, and clinical researchers in the fields of biology, biomedical engineering, chemistry and medicine working on applications of fluid flow, heat transfer, and transport phenomena in biomedical technology. Provides a wide range of biological and clinical applications of fluid...

  18. A CW Gunn Diode Switching Element.

    Science.gov (United States)

    Hurtado, Marco; Rosenbaum, Fred J.

    As part of a study of the application of communication satellites to educational development, certain technical aspects of such a system were examined. A current controlled bistable switching element using a CW Gunn diode is reported on here. With modest circuits switching rates of the order of 10 MHz have been obtained. Switching is initiated by…

  19. Determining Extinction Ratio Of A Laser Diode

    Science.gov (United States)

    Unger, Glenn L.

    1992-01-01

    Improved technique to determine extinction ratio of pulsed laser diode based partly on definition of extinction ratio applicable to nonideal laser pulses. Heretofore, determinations involved assumption of ideal laser pulses, and neglected optical power from background light. Because power fluctuates during real pulse, more realistic to define extinction ratio in terms of energy obtained.

  20. Solar spectrum rectification using nano-antennas and tunneling diodes

    Science.gov (United States)

    Dagenais, Mario; Choi, Kwangsik; Yesilkoy, Filiz; Chryssis, Athanasios N.; Peckerar, Martin C.

    2010-02-01

    Our goal is to develop a rectifying antenna (rectenna) applicable to solar spectrum energy harvesting. In particular, we aim to demonstrate viable techniques for converting portion of the solar spectrum not efficiently converted to electric power by current photovoltaic approaches. Novel design guidelines are suggested for rectifying antenna coupled tunneling diodes. We propose a new geometric field enhancement scheme in antenna coupled tunneling diodes that uses surface plasmon resonances. For this purpose, we have successfully implemented a planar tunneling diode with polysilion/SiO2/polysilcon structure. An antenna coupled asymmetric tunneling diode is developed with a pointed triangle electrode for geometric field enhancement. The geometrically asymmetric tunneling diode shows a unique asymmetric tunneling current versus voltage characteristic. Through comparison with crossover tunneling diodes, we verified that the current asymmetry is not from the work function difference between the two electrodes. Results of RF rectification tests using the asymmetric diode demonstrate that our approach is practical for energy harvesting application. Furthermore, we describe how surface plasmons can enhance the electric field across the tunnel junction, lowering the effective "turn-on" voltage of the diode, further improving rectification efficiency.

  1. Progress in the Development of Compressible, Multiphase Flow Modeling Capability for Nuclear Reactor Flow Applications

    Energy Technology Data Exchange (ETDEWEB)

    R. A. Berry; R. Saurel; F. Petitpas; E. Daniel; O. Le Metayer; S. Gavrilyuk; N. Dovetta

    2008-10-01

    In nuclear reactor safety and optimization there are key issues that rely on in-depth understanding of basic two-phase flow phenomena with heat and mass transfer. Within the context of multiphase flows, two bubble-dynamic phenomena – boiling (heterogeneous) and flashing or cavitation (homogeneous boiling), with bubble collapse, are technologically very important to nuclear reactor systems. The main difference between boiling and flashing is that bubble growth (and collapse) in boiling is inhibited by limitations on the heat transfer at the interface, whereas bubble growth (and collapse) in flashing is limited primarily by inertial effects in the surrounding liquid. The flashing process tends to be far more explosive (and implosive), and is more violent and damaging (at least in the near term) than the bubble dynamics of boiling. However, other problematic phenomena, such as crud deposition, appear to be intimately connecting with the boiling process. In reality, these two processes share many details.

  2. Phase-change radiative thermal diode

    CERN Document Server

    Ben-Abdallah, Philippe

    2013-01-01

    A thermal diode transports heat mainly in one preferential direction rather than in the opposite direction. This behavior is generally due to the non-linear dependence of certain physical properties with respect to the temperature. Here we introduce a radiative thermal diode which rectifies heat transport thanks to the phase transitions of materials. Rectification coefficients greater than 70% and up to 90% are shown, even for small temperature differences. This result could have important applications in the development of futur contactless thermal circuits or in the conception of radiative coatings for thermal management.

  3. Second-order Data by Flow Injection Analysis with Spectrophotometric Diode-array Detection and Incorporated Gel-filtration Chromatographic Column

    DEFF Research Database (Denmark)

    Bechmann, Iben Ellegaard

    1997-01-01

    A flow injection analysis (FIA) system furnished with a gel-filtration chromatographic column and with photodiode-array detection was used for the generation of second-order data. The system presented is a model system in which the analytes are blue dextran, potassium hexacyanoferrate......(III) and heparin. It is shown that the rank of the involved sample data matrices corresponds to the number of chemical components present in the sample. The PARAFAC (parallel factor analysis) algorithm combined with multiple linear regression and the tri-PLS (tri-linear partial least-squares regression), which...

  4. Dual-Functional On-Chip AlGaAs/GaAs Schottky Diode for RF Power Detection and Low-Power Rectenna Applications

    Directory of Open Access Journals (Sweden)

    Abdul Manaf Hashim

    2011-08-01

    Full Text Available A Schottky diode has been designed and fabricated on an n-AlGaAs/GaAs high-electron-mobility-transistor (HEMT structure. Current-voltage (I-V measurements show good device rectification, with a Schottky barrier height of 0.4349 eV for Ni/Au metallization. The differences between the Schottky barrier height and the theoretical value (1.443 eV are due to the fabrication process and smaller contact area. The RF signals up to 1 GHz are rectified well by the fabricated Schottky diode and a stable DC output voltage is obtained. The increment ratio of output voltage vs input power is 0.2 V/dBm for all tested frequencies, which is considered good enough for RF power detection. Power conversion efficiency up to 50% is obtained at frequency of 1 GHz and input power of 20 dBm with series connection between diode and load, which also shows the device’s good potential as a rectenna device with further improvement. The fabricated n-AlGaAs/GaAs Schottky diode thus provides a conduit for breakthrough designs for RF power detectors, as well as ultra-low power on-chip rectenna device technology to be integrated in nanosystems.

  5. Fabrication of microfluidic architectures for optimal flow rate and concentration measurement for lab on chip application

    Science.gov (United States)

    Adam, Tijjani; Hashim, U.

    2017-03-01

    Optimum flow in micro channel for sensing purpose is challenging. In this study, The optimizations of the fluid sample flows are made through the design and characterization of the novel microfluidics' architectures to achieve the optimal flow rate in the micro channels. The biocompatibility of the Polydimetylsiloxane (Sylgard 184 silicon elastomer) polymer used to fabricate the device offers avenue for the device to be implemented as the universal fluidic delivery system for bio-molecules sensing in various bio-medical applications. The study uses the following methodological approaches, designing a novel microfluidics' architectures by integrating the devices on a single 4 inches silicon substrate, fabricating the designed microfluidic devices using low-cost solution soft lithography technique, characterizing and validating the flow throughput of urine samples in the micro channels by generating pressure gradients through the devices' inlets. The characterization on the urine samples flow in the micro channels have witnessed the constant flow throughout the devices.

  6. Application of vector finite volume method for electromagnetic flow simulation

    Energy Technology Data Exchange (ETDEWEB)

    Takata, T.; Murashige, R.; Matsumoto, T.; Yamaguchi, A. [Osaka Univ., Suita, Osaka (Japan)

    2011-07-01

    A vector finite volume method (VFVM) has been developed for an electromagnetic flow analysis. In the VFVM, the governing equations of magnetic flux density and electric field intensity are solved separately so as to reduce the computational cost caused by an iterative procedure that is required to satisfy the solenoidal condition. In the present paper, a suppression of temperature fluctuation of liquid sodium after a T-junction has also been investigated with a simplified two dimensional numerical analysis by adding an obstacle (turbulence promoter) or a magnetic field after the junction. (author)

  7. Organic light-emitting diodes: High-throughput virtual screening

    Science.gov (United States)

    Hirata, Shuzo; Shizu, Katsuyuki

    2016-10-01

    Computer networks, trained with data from delayed-fluorescence materials that have been successfully used in organic light-emitting diodes, facilitate the high-speed prediction of good emitters for display and lighting applications.

  8. Drivers for High Power Laser Diodes

    Institute of Scientific and Technical Information of China (English)

    Yankov P; Todorov D; Saramov E

    2006-01-01

    During the last year the high power laser diodes jumped over the 1 kW level of CW power for a stack,and the commercial 1 cm bars reached 100 W output optical power at the standard wavelengths around 800 nm and 980 nm. The prices are reaching the industry acceptable levels. All Nd:YAG and fiber industrial lasers manufacturers have developed kW prototypes. Those achievements have set new requirements for the power supplies manufactuers-high and stable output current, and possibilities for fast control of the driving current, keeping safe the expensive laser diode. The fast switching frequencies also allow long range free space communications and optical range finding. The high frequencies allow the design of a 3D laser radar with high resolution and other military applications. The prospects for direct laser diode micro machining are also attractive.

  9. Optical communications. V - Light emitting diodes /LED/

    Science.gov (United States)

    Best, S. W.

    1980-10-01

    The process of assembling diode chips is discussed, along with their application in optical communications. Metal plating is performed with an evaporation technique using primarily AuGe on the back side and Al or AuZn on the front side. The assembling of LED-chips with metal casings is illustrated. The chip is mounted on a flat bottom plate and electrical contact is established by means of an alloying or adhesion procedure. A glass fiber can be attached to the diode and then fitted with a casing, or the diode can be assembled with a metal cap and a lense, or with an open cap that is sealed with a clear synthetic resin plastic. The typical emission spectra of an LED and a semiconductor laser are compared. Limitations in the operation of an LED in a photoconductor are examined, taking into account spectral line width and radiated power criteria.

  10. Poly (3,4-ethylenedioxythiophene) (PEDOT) and poly (3,4-ethylenedioxythiophene)-few walled carbon nanotube (PEDOT-FWCNT) nanocomposite based thin films for Schottky diode application

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Bhavana, E-mail: bgupta1206@gmail.com [Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre of Atomic Research, Kalpakkam, Tamil Nadu 603102 (India); Mehta, Minisha, E-mail: mehta.mini@gmail.com [Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre of Atomic Research, Kalpakkam, Tamil Nadu 603102 (India); Melvin, Ambrose [Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha, Pune 411008 (India); Kamalakannan, R.; Dash, S.; Kamruddin, M.; Tyagi, A.K. [Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre of Atomic Research, Kalpakkam, Tamil Nadu 603102 (India)

    2014-10-15

    Transparent, conductive films of poly (3,4-ethylenedioxythiophene) (PEDOT) and poly (3,4-ethylenedioxythiophene)-few walled carbon nanotube (PEDOT-FWCNT) nanocomposite were synthesized by in-situ oxidative polymerization and investigated for their Schottky diode property. The prepared films were characterized by UV–Vis spectroscopy, thermal gravimetric analysis (TGA), surface resistivity, cyclic voltametery, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). SEM reveals the formation of homogeneous and adhesive polymer films while HRTEM confirms the uniform wrapping of polymer chains around the nanotube walls for PEDOT-FWCNT film. Improved thermal stability, conductivity and charge storage property of PEDOT in the presence of FWCNT is observed. Among different compositions, 5 wt. % of FWCNT is found to be optimum with sheet resistance and transmittance of 500 Ω sq{sup −1} and 77%, respectively. Moreover, the electronic and junction properties of polymer films were studied and compared by fabricating sandwich type devices with a configuration of Al/PEDOT or PEDOT-FWCNT nanocomposite/indium tin oxide (ITO) coated glass. The measured current density-voltage characteristics show typical rectifying behavior for both configurations. However, enhanced rectification ratio and higher forward current density is observed in case of PEDOT-FWCNT based Schottky diode. Furthermore, reliability test depicts smaller hysteresis effect and better performance of PEDOT-FWCNT based diodes. - Highlights: • Single step synthesis of PEDOT and PEDOT-FWCNT nanocomposites films via in-situ oxidative polymerization. • Thermal, electrical and electrochemical properties of films show positive effect of FWCNT on PEDOT films. • Schottky diodes based on metal Al/PEDOT or PEDOT-FWCNT composites/ITO glass are fabricated. • Improved electrical characteristics with better reliability is achieved for PEDOT-FWCNT based diodes.

  11. 78 FR 58301 - Go With the Flow Hydro Power, LLC; Notice of Preliminary Permit Application Accepted for Filing...

    Science.gov (United States)

    2013-09-23

    ... Energy Regulatory Commission Go With the Flow Hydro Power, LLC; Notice of Preliminary Permit Application..., 2013, Go with the Flow Hydro Power, LLC, filed an application for a preliminary permit, pursuant to section 4(f) of the Federal Power Act (FPA), proposing to study the feasibility of the Go with the Flow...

  12. Computational Methods for Feedback Controllers for Aerodynamics Flow Applications

    Science.gov (United States)

    2007-08-15

    estimating that particular mode (Bayon de Noyer 1999). The above heuristic approach has been used by Bayon de Noyer (1999) in finding effective sensor...Systems", Journal of Optimization Theory and Applications, Vol. 25, No. 3, 1978, pp. 217-236. Bayon de Noyer , "Tail Buffet Alleviation of High

  13. Quantitative Application Data Flow Characterization for Heterogeneous Multicore Architectures

    NARCIS (Netherlands)

    Ostadzadeh, S.A.

    2012-01-01

    Recent trends show a steady increase in the utilization of heterogeneous multicore architectures in order to address the ever-growing need for computing performance. These emerging architectures pose specific challenges with regard to their programmability. In addition, they require efficient applic

  14. Flow Cytometric Applicability of Fluorescent Vitality Probes on Phytoplankton

    NARCIS (Netherlands)

    Peperzak, L.; Brussaard, C.P.D.

    2011-01-01

    The applicability of six fluorescent probes (four esterase probes: acetoxymethyl ester of Calcein [Calcein-AM], 5-chloromethylfluorescein diacetate [CMFDA], fluorescein diacetate [FDA], and 2',7'-dichlorofluorescein diacetate [H(2)DCFDA]; and two membrane probes: bis-(1,3-dibutylbarbituric acid) tri

  15. Hermetic diode laser transmitter module

    Science.gov (United States)

    Ollila, Jyrki; Kautio, Kari; Vahakangas, Jouko; Hannula, Tapio; Kopola, Harri K.; Oikarinen, Jorma; Sivonen, Matti

    1999-04-01

    In very demanding optoelectronic sensor applications it is necessary to encapsulate semiconductor components hermetically in metal housings to ensure reliable operation of the sensor. In this paper we report on the development work to package a laser diode transmitter module for a time- off-light distance sensor application. The module consists of a lens, laser diode, electronic circuit and optomechanics. Specifications include high acceleration, -40....+75 degree(s)C temperature range, very low gas leakage and mass-production capability. We have applied solder glasses for sealing optical lenses and electrical leads hermetically into a metal case. The lens-metal case sealing has been made by using a special soldering glass preform preserving the optical quality of the lens. The metal housings are finally sealed in an inert atmosphere by welding. The assembly concept to retain excellent optical power and tight optical axis alignment specifications is described. The reliability of the laser modules manufactured has been extensively tested using different aging and environmental test procedures. Sealed packages achieve MIL- 883 standard requirements for gas leakage.

  16. Misty Mountain clustering: application to fast unsupervised flow cytometry gating

    Directory of Open Access Journals (Sweden)

    Sealfon Stuart C

    2010-10-01

    Full Text Available Abstract Background There are many important clustering questions in computational biology for which no satisfactory method exists. Automated clustering algorithms, when applied to large, multidimensional datasets, such as flow cytometry data, prove unsatisfactory in terms of speed, problems with local minima or cluster shape bias. Model-based approaches are restricted by the assumptions of the fitting functions. Furthermore, model based clustering requires serial clustering for all cluster numbers within a user defined interval. The final cluster number is then selected by various criteria. These supervised serial clustering methods are time consuming and frequently different criteria result in different optimal cluster numbers. Various unsupervised heuristic approaches that have been developed such as affinity propagation are too expensive to be applied to datasets on the order of 106 points that are often generated by high throughput experiments. Results To circumvent these limitations, we developed a new, unsupervised density contour clustering algorithm, called Misty Mountain, that is based on percolation theory and that efficiently analyzes large data sets. The approach can be envisioned as a progressive top-down removal of clouds covering a data histogram relief map to identify clusters by the appearance of statistically distinct peaks and ridges. This is a parallel clustering method that finds every cluster after analyzing only once the cross sections of the histogram. The overall run time for the composite steps of the algorithm increases linearly by the number of data points. The clustering of 106 data points in 2D data space takes place within about 15 seconds on a standard laptop PC. Comparison of the performance of this algorithm with other state of the art automated flow cytometry gating methods indicate that Misty Mountain provides substantial improvements in both run time and in the accuracy of cluster assignment. Conclusions

  17. Directed and diode percolation

    Science.gov (United States)

    Redner, S.

    1982-03-01

    We study the novel percolation phenomena that occur in random-lattice networks consisting of resistor-like and diode-like bonds. Resistor bonds connect or "transmit information" in either direction along their length, while diodes connect in one direction only. We first treat the special case of directed bond percolation, in which the diodes are aligned along a preferred axis. Mean-field theory shows that clusters become extremely anisotropic near the percolation transition and that their shapes are characterized by two correlation lengths, one parallel and one transverse to the preferred axis. These lengths diverge with exponents ν∥=1 and ν⊥=12, respectively, from which we can show that the upper critical dimension for this system must be five. We also treat a more general random network on the square lattice containing resistors and diodes of arbitrary orientation. Duality arguments are applied to obtain exact results for the location of phase transitions in this system. We then use a position-space renormalization-group approach to map out the phase diagram and calculate critical exponents. This system has an isotropic percolating phase, and phases which percolate in only one direction. Novel types of transitions occur between these phases, in which the diode orientation plays a fundamental role. These percolating phases meet with the nonpercolating phase along a line of multicritical points, where concentration and orientational fluctuations are simultaneously critical.

  18. Construction of an X-ray detecting module and its application to relative-sensitivity measurement using a silicon PIN diode in conjunction with short-decay-time scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, Shinichi [Department of Physics, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba, Iwate 028-3694 (Japan); Sato, Eiichi, E-mail: dresato@iwate-med.ac.jp [Department of Physics, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba, Iwate 028-3694 (Japan); Hamaya, Tatsuki; Numahata, Wataru; Kogita, Hayato; Kami, Syouta; Arakawa, Yumeka; Oda, Yasuyuki [Department of Physics, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba, Iwate 028-3694 (Japan); Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya [Department of Surgery, Toho University Ohashi Medical Center, 2-17-6 Ohashi, Meguro, Tokyo 153-8515 (Japan)

    2014-12-11

    To detect low-dose-rate X-rays, we have developed an X-ray-detecting module for semiconductor diodes. The module consists of a current–voltage (I–V) amplifier, a voltage–voltage (V–V) amplifier, and an alternating-current adopter with a smoothing circuit. The photocurrents flowing through a diode are converted into voltages and amplified using the I–V and V–V amplifiers. To measure relative sensitivities, we used three silicon PIN diodes (Si-PIN), a cerium-doped yttrium aluminum perovskite [YAP(Ce)] crystal, and a Lu{sub 2}(SiO{sub 4})O [LSO] crystal. Three detectors are as follows: an Si-PIN, a YAP(Ce)–Si-PIN, and an LSO–Si-PIN. Using the three detectors, the amplifier output voltages were in proportion to the tube current at a constant tube voltage of 70 kV. Using a multichannel analyzer, the event-pulse-height spectra were measured to analyze X-ray-electric conversion effect in the three detectors. The output voltage of the Si-PIN was approximately twice as high as those obtained using the YAP(Ce)–Si-PIN and the LSO–Si-PIN at the measurement conditions. - Highlights: • X-ray detecting module was developed to measure relative sensitivities of detectors. • Event-pulse-height spectra were measured to analyze X-ray-electric conversion effect. • Total photon number substantially decreased using scintillation detectors. • Scintillation effects using YAP(Ce) and LSO were quite low. • Si-PIN sensitivity without scintillators was quite high.

  19. Vortex Diode Analysis and Testing for Fluoride Salt-Cooled High-Temperature Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Yoder Jr, Graydon L [ORNL; Elkassabgi, Yousri M. [Texas A& M University, Kingsville; De Leon, Gerardo I. [Texas A& M University, Kingsville; Fetterly, Caitlin N. [Texas A& M University, Kingsville; Ramos, Jorge A. [Texas A& M University, Kingsville; Cunningham, Richard Burns [University of Tennessee, Knoxville (UTK)

    2012-02-01

    Fluidic diodes are presently being considered for use in several fluoride salt-cooled high-temperature reactor designs. A fluidic diode is a passive device that acts as a leaky check valve. These devices are installed in emergency heat removal systems that are designed to passively remove reactor decay heat using natural circulation. The direct reactor auxiliary cooling system (DRACS) uses DRACS salt-to-salt heat exchangers (DHXs) that operate in a path parallel to the core flow. Because of this geometry, under normal operating conditions some flow bypasses the core and flows through the DHX. A flow diode, operating in reverse direction, is-used to minimize this flow when the primary coolant pumps are in operation, while allowing forward flow through the DHX under natural circulation conditions. The DRACSs reject the core decay heat to the environment under loss-of-flow accident conditions and as such are a reactor safety feature. Fluidic diodes have not previously been used in an operating reactor system, and therefore their characteristics must be quantified to ensure successful operation. This report parametrically examines multiple design parameters of a vortex-type fluidic diode to determine the size of diode needed to reject a particular amount of decay heat. Additional calculations were performed to size a scaled diode that could be tested in the Oak Ridge National Laboratory Liquid Salt Flow Loop. These parametric studies have shown that a 152.4 mm diode could be used as a test article in that facility. A design for this diode is developed, and changes to the loop that will be necessary to test the diode are discussed. Initial testing of a scaled flow diode has been carried out in a water loop. The 150 mm diode design discussed above was modified to improve performance, and the final design tested was a 171.45 mm diameter vortex diode. The results of this testing indicate that diodicities of about 20 can be obtained for diodes of this size. Experimental

  20. A THERMODYNAMIC CAVITATION MODEL APPLICABLE TO HIGH TEMPERATURE FLOW

    Directory of Open Access Journals (Sweden)

    De-Min Liu

    2011-01-01

    Full Text Available Cavitation is not only related with pressure, but also affected by temperature. Under high temperature, temperature depression of liquids is caused by latent heat of vaporization. The cavitation characteristics under such condition are different from those under room temperature. The paper focuses on thermodynamic cavitation based on the Rayleigh-Plesset equation and modifies the mass transfer equation with fully consideration of the thermodynamic effects and physical properties. To validate the modified model, the external and internal flow fields, such as hydrofoil NACA0015 and nozzle, are calculated, respectively. The hydrofoil NACA0015's cavitation characteristic is calculated by the modified model at different temperatures. The pressure coefficient is found in accordance with the experimental data. The nozzle cavitation under the thermodynamic condition is calculated and compared with the experiment.

  1. Diode Laser Sensor for Scramjet Inlet

    Science.gov (United States)

    2010-05-11

    Conference’. 1.2 O’Byrne, S., Huynh, L., Wittig, S. M. and Smith, N. S. A. (2009), Non- intrusive water vapour absorp- tion measurements in a simulated...O’Byrne, L. Huynh, S. M. Wittig and N. S. A. Smith, “Non- intrusive Water Vapour Absorp- tion Measurements in a Simulated Helicopter Exhaust”, Proceedings...rather than at a surface. The measurement techniques used at these hypersonic flow conditions should also be non- intrusive . Tuneable diode laser

  2. Semiconductor Laser Diode Pumps for Inertial Fusion Energy Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Deri, R J

    2011-01-03

    Solid-state lasers have been demonstrated as attractive drivers for inertial confinement fusion on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) and at the Omega Facility at the Laboratory for Laser Energetics (LLE) in Rochester, NY. For power plant applications, these lasers must be pumped by semiconductor diode lasers to achieve the required laser system efficiency, repetition rate, and lifetime. Inertial fusion energy (IFE) power plants will require approximately 40-to-80 GW of peak pump power, and must operate efficiently and with high system availability for decades. These considerations lead to requirements on the efficiency, price, and production capacity of the semiconductor pump sources. This document provides a brief summary of these requirements, and how they can be met by a natural evolution of the current semiconductor laser industry. The detailed technical requirements described in this document flow down from a laser ampl9ifier design described elsewhere. In brief, laser amplifiers comprising multiple Nd:glass gain slabs are face-pumped by two planar diode arrays, each delivering 30 to 40 MW of peak power at 872 nm during a {approx} 200 {micro}s quasi-CW (QCW) pulse with a repetition rate in the range of 10 to 20 Hz. The baseline design of the diode array employs a 2D mosaic of submodules to facilitate manufacturing. As a baseline, they envision that each submodule is an array of vertically stacked, 1 cm wide, edge-emitting diode bars, an industry standard form factor. These stacks are mounted on a common backplane providing cooling and current drive. Stacks are conductively cooled to the backplane, to minimize both diode package cost and the number of fluid interconnects for improved reliability. While the baseline assessment in this document is based on edge-emitting devices, the amplifier design does not preclude future use of surface emitting diodes, which may offer appreciable future cost reductions and

  3. Large eddy simulations of turbulent flows on graphics processing units: Application to film-cooling flows

    Science.gov (United States)

    Shinn, Aaron F.

    Computational Fluid Dynamics (CFD) simulations can be very computationally expensive, especially for Large Eddy Simulations (LES) and Direct Numerical Simulations (DNS) of turbulent ows. In LES the large, energy containing eddies are resolved by the computational mesh, but the smaller (sub-grid) scales are modeled. In DNS, all scales of turbulence are resolved, including the smallest dissipative (Kolmogorov) scales. Clusters of CPUs have been the standard approach for such simulations, but an emerging approach is the use of Graphics Processing Units (GPUs), which deliver impressive computing performance compared to CPUs. Recently there has been great interest in the scientific computing community to use GPUs for general-purpose computation (such as the numerical solution of PDEs) rather than graphics rendering. To explore the use of GPUs for CFD simulations, an incompressible Navier-Stokes solver was developed for a GPU. This solver is capable of simulating unsteady laminar flows or performing a LES or DNS of turbulent ows. The Navier-Stokes equations are solved via a fractional-step method and are spatially discretized using the finite volume method on a Cartesian mesh. An immersed boundary method based on a ghost cell treatment was developed to handle flow past complex geometries. The implementation of these numerical methods had to suit the architecture of the GPU, which is designed for massive multithreading. The details of this implementation will be described, along with strategies for performance optimization. Validation of the GPU-based solver was performed for fundamental bench-mark problems, and a performance assessment indicated that the solver was over an order-of-magnitude faster compared to a CPU. The GPU-based Navier-Stokes solver was used to study film-cooling flows via Large Eddy Simulation. In modern gas turbine engines, the film-cooling method is used to protect turbine blades from hot combustion gases. Therefore, understanding the physics of

  4. Application of asymmetric flow-field flow fractionation to the characterization of colloidal dispersions undergoing aggregation.

    Science.gov (United States)

    Lattuada, Marco; Olivo, Carlos; Gauer, Cornelius; Storti, Giuseppe; Morbidelli, Massimo

    2010-05-18

    The characterization of complex colloidal dispersions is a relevant and challenging problem in colloidal science. In this work, we show how asymmetric flow-field flow fractionation (AF4) coupled to static light scattering can be used for this purpose. As an example of complex colloidal dispersions, we have chosen two systems undergoing aggregation. The first one is a conventional polystyrene latex undergoing reaction-limited aggregation, which leads to the formation of fractal clusters with well-known structure. The second one is a dispersion of elastomeric colloidal particles made of a polymer with a low glass transition temperature, which undergoes coalescence upon aggregation. Samples are withdrawn during aggregation at fixed times, fractionated with AF4 using a two-angle static light scattering unit as a detector. We have shown that from the analysis of the ratio between the intensities of the scattered light at the two angles the cluster size distribution can be recovered, without any need for calibration based on standard elution times, provided that the geometry and scattering properties of particles and clusters are known. The nonfractionated samples have been characterized also by conventional static and dynamic light scattering to determine their average radius of gyration and hydrodynamic radius. The size distribution of coalescing particles has been investigated also through image analysis of cryo-scanning electron microscopy (SEM) pictures. The average radius of gyration and the average hydrodynamic radius of the nonfractionated samples have been calculated and successfully compared to the values obtained from the size distributions measured by AF4. In addition, the data obtained are also in good agreement with calculations made with population balance equations.

  5. Modeling of Multisize Bubbly Flow and Application to the Simulation of Boiling Flows with the Neptune_CFD Code

    Directory of Open Access Journals (Sweden)

    Christophe Morel

    2009-01-01

    Full Text Available This paper describes the modeling of boiling multisize bubbly flows and its application to the simulation of the DEBORA experiment. We follow the method proposed originally by Kamp, assuming a given mathematical expression for the bubble diameter pdf. The original model is completed by the addition of some new terms for vapor compressibility and phase change. The liquid-to-interface heat transfer term, which essentially determines the bubbles condensation rate in the DEBORA experiment, is also modeled with care. First numerical results realized with the Neptune_CFD code are presented and discussed.

  6. Symplectic Exact Solution for Stokes Flow in the Thin Film Coating Applications

    Directory of Open Access Journals (Sweden)

    Yan Wang

    2014-01-01

    Full Text Available The symplectic analytical method is introduced to solve the problem of the stokes flow in the thin film coating applications. Based on the variational principle, the Lagrangian function of the stokes flow is established. By using the Legendre transformation, the dual variables of velocities and the Hamiltonian function are derived. Considering velocities and stresses as the basic variables, the equations of stokes flow problems are transformed into Hamiltonian system. The method of separation of variables and expansion of eigenfunctions are developed to solve the governing equations in Hamiltonian system, and the analytical solutions of the stokes flow are obtained. Several numerical simulations are carried out to verify the analytical solutions in the present study and discuss the effects of the driven lids of the square cavity on the dynamic behavior of the flow structure.

  7. Extracted Electronic Parameters of a Novel Ag/SnO2:In/Si/Au Schottky Diode for Solar Cell Application

    Directory of Open Access Journals (Sweden)

    Mostefa Benhaliliba

    2015-06-01

    Full Text Available The effect of indium on the characteristics of Ag / SnO2 : In / Si / Au Schottky diode (SD is studied. The electronic parameters, ideal factor, the effective barrier, flat band barrier height, the series resistance, the saturation current density of the diodes were extracted from the current voltage (I-V and capacitance voltage (C-V characteristics. The series resistance (Rs determined by Cheung method increases (508-534 Ω with In doping level while the barrier height still constant around 0.57 V. Norde approximation gives a similar barrier height values of 0.69 V but the series resistance reaches higher values of 5500 Ω.

  8. Accurate surface potential determination in Schottky diodes by the use of a correlated current and capacitance voltage measurements.Application to n-InP

    Institute of Scientific and Technical Information of China (English)

    Ali Ahaitouf; Abdelaziz Ahaitouf; Jean Paul Salvestrini; Hussein Srour

    2011-01-01

    Based on current voltage (I-Vg) and capacitance voltage (C-Vg) measurements,a reliable procedure is proposed to determine the effective surface potential Vd (Vg) in Schottky diodes.In the framework of thermionic emission,our analysis includes both the effect of the series resistance and the ideality factor,even voltage dependent.This technique is applied to n-type indium phosphide (n-InP) Schottky diodes with and without an interfacial layer and allows us to provide an interpretation of the observed peak on the C-Vg measurements.The study clearly shows that the depletion width and the flat band barrier height deduced from C-Vg,which are important parameters directly related to the surface potential in the semiconductor,should be estimated within our approach to obtain more reliable information.

  9. Parallel flow accumulation algorithms for graphical processing units with application to RUSLE model

    Science.gov (United States)

    Sten, Johan; Lilja, Harri; Hyväluoma, Jari; Westerholm, Jan; Aspnäs, Mats

    2016-04-01

    Digital elevation models (DEMs) are widely used in the modeling of surface hydrology, which typically includes the determination of flow directions and flow accumulation. The use of high-resolution DEMs increases the accuracy of flow accumulation computation, but as a drawback, the computational time may become excessively long if large areas are analyzed. In this paper we investigate the use of graphical processing units (GPUs) for efficient flow accumulation calculations. We present two new parallel flow accumulation algorithms based on dependency transfer and topological sorting and compare them to previously published flow transfer and indegree-based algorithms. We benchmark the GPU implementations against industry standards, ArcGIS and SAGA. With the flow-transfer D8 flow routing model and binary input data, a speed up of 19 is achieved compared to ArcGIS and 15 compared to SAGA. We show that on GPUs the topological sort-based flow accumulation algorithm leads on average to a speedup by a factor of 7 over the flow-transfer algorithm. Thus a total speed up of the order of 100 is achieved. We test the algorithms by applying them to the Revised Universal Soil Loss Equation (RUSLE) erosion model. For this purpose we present parallel versions of the slope, LS factor and RUSLE algorithms and show that the RUSLE erosion results for an area of 12 km x 24 km containing 72 million cells can be calculated in less than a second. Since flow accumulation is needed in many hydrological models, the developed algorithms may find use in many other applications than RUSLE modeling. The algorithm based on topological sorting is particularly promising for dynamic hydrological models where flow accumulations are repeatedly computed over an unchanged DEM.

  10. Experience of application of clamp-on cross-correlation flow meter in nuclear industry

    Energy Technology Data Exchange (ETDEWEB)

    Gurevich, Y. [Daystar Technology Inc., Ontario (Canada); Ton, V.; Kotenyov, S.; Zhao, C. [Ontario Power Generation, Ontario (Canada); Sharp, B.; Lopez, A. [Advanced Measurements and Analysis Group Inc., Ontario (Canada)

    2010-07-01

    The cross-correlation clamp-on flow meter, CROSSFLOW, developed and manufactured by AMAG, has been used over the world for over 15 years for flow measurements in various systems in nuclear and fossil power plants. Prior that, OPG has used similar technology in Canadian nuclear power plants since 1980-ies. Two recent examples of the application of the clamp-on cross-correlation technology are presented in this paper. In first example OPG meter was used to verify accuracy of ASME nozzles installed in condensate flow lines. In second example AMAG meter was used to measure Diesel Cooling Water (DCW). (author)

  11. A constant air flow rate control of blower for residential applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S.M. [Tamkang Univ., Taipei (Taiwan, Province of China). Dept. of Mechanical Engineering

    1998-03-01

    This paper presents a technique to control a blower for residential applications at constant air flow rate using an induction motor drive. The control scheme combines a variable volt/hertz ratio inverter drive and an average motor current regulation loop to achieve control of the motor torque-speed characteristics, consequently controlling the air flow rate of the blower which the motor is driving. The controller is simple to implement and practical for commercialization. It is also reliable, since no external pressure or air flow sensor is required. Both a theoretical derivation and an experimental verification for the control scheme are presented in this paper.

  12. Applications of Continuous-Flow Photochemistry in Organic Synthesis, Material Science, and Water Treatment.

    Science.gov (United States)

    Cambié, Dario; Bottecchia, Cecilia; Straathof, Natan J W; Hessel, Volker; Noël, Timothy

    2016-09-14

    Continuous-flow photochemistry in microreactors receives a lot of attention from researchers in academia and industry as this technology provides reduced reaction times, higher selectivities, straightforward scalability, and the possibility to safely use hazardous intermediates and gaseous reactants. In this review, an up-to-date overview is given of photochemical transformations in continuous-flow reactors, including applications in organic synthesis, material science, and water treatment. In addition, the advantages of continuous-flow photochemistry are pointed out and a thorough comparison with batch processing is presented.

  13. A gradiometric version of contactless inductive flow tomography: theory and first applications.

    Science.gov (United States)

    Ratajczak, Matthias; Wondrak, Thomas; Stefani, Frank

    2016-06-28

    The contactless inductive flow tomography (CIFT) is a measurement technique that allows reconstructing the flow of electrically conducting fluids by measuring the flow-induced perturbations of one or various applied magnetic fields and solving the underlying inverse problem. One of the most promising application fields of CIFT is the continuous casting of steel, for which the online monitoring of the flow in the mould would be highly desirable. In previous experiments at a small-scale model of continuous casting, CIFT has been applied to various industrially relevant problems, including the sudden changes of flow structures in case of argon injection and the influence of a magnetic stirrer at the submerged entry nozzle. The application of CIFT in the presence of electromagnetic brakes, which are widely used to stabilize the flow in the mould, has turned out to be more challenging due to the extreme dynamic range between the strong applied brake field and the weak flow-induced perturbations of the measuring field. In this paper, we present a gradiometric version of CIFT, relying on gradiometric field measurements, that is capable to overcome those problems and which seems, therefore, a promising candidate for applying CIFT in the steel casting industry. This article is part of the themed issue 'Supersensing through industrial process tomography'.

  14. A study of Eu incorporated ZnO thin films: An application of Al/ZnO:Eu/p-Si heterojunction diode

    Energy Technology Data Exchange (ETDEWEB)

    Turgut, G. [Department of Basic Sciences, Faculty of Science, Erzurum Technical University, Erzurum, 25240 (Turkey); Duman, S., E-mail: sduman@atauni.edu.tr [Department of Physics, Faculty of Science, Ataturk University, Erzurum, 25240 (Turkey); Sonmez, E. [Department of Physics, Faculty of K.K. Education, Ataturk University, Erzurum, 25240 (Turkey); Ozcelik, F.S. [Department of Physics, Faculty of Science, Ataturk University, Erzurum, 25240 (Turkey)

    2016-04-15

    Highlights: • Eu incorporated ZnO thin films were grown by sol–gel spin coating. • The influence of Eu contribution on features of ZnO was investigated. • Al/ZnO:Eu/p-Si heterojunction diodes were also fabricated. • The diode parameters were calculated from I–V measurements. - Abstract: In present work, the pure and europium (Eu) incorporated zinc oxide (ZnO) thin films were deposited with sol-gel spin coating by using zinc acetate dehydrate and Eu (III) chloride salts. The coated films were examined by means of XRD, AFM and UV/VIS spectrophotometer. The ZnO hexagonal wurtzite nanoparticles with (002) preferential direction were observed for all films. The values of crystallite size, micro-strain and surface roughness continuously increased from 21 nm, 1.10 × 10{sup −3} and 2.43 nm to the values of 35.56 nm, 1.98 × 10{sup −3} and 28.99 nm with Eu doping, respectively. The optical band gap value of the pure ZnO initially increased from 3.296 eV to 3.328 eV with Eu doping up to 2 at.% doping level, then it started to decrease with more Eu content. The electrical features of Al/n-ZnO:Eu/p-Si heterojunction diodes were inquired by current-voltage (I–V) measurements at the room temperature.

  15. Method and applications of fiber synthesis using laminar flow

    Science.gov (United States)

    Burns, Bradley Justin

    A Laminar Flow Reactor (LFR) using the principles of hydrodynamic focusing was created and used to fabricate functional composite polymer fibers. These fibers had the ability to conduct or serve as a carrier for singlet oxygen-generating molecules. Critical to the process was designing an easy-to-fabricate, inexpensive device and developing a repeatable method that made efficient use of the materials. The initial designs used a planar layout and hydrodynamically focused in only one dimension while later versions switched to a two-fluid concentric design. Modeling was undertaken and verified for the different device layouts. Three types of conductive particles were embedded in the formed polymer: silver, indium tin oxide (ITO) and polyaniline. The polymer was also used as a carrier to two singlet oxygen generating molecules: Methylene Blue (MB) and perylene. Both were effective in killing Bacillus thuringiensis but MB leached from the fiber into the tested cell suspension. Perylene, which is not water soluble, did not leach out and was just as effective as MB. Research that was performed at ITT is also presented. A critical need exists to detect, identify, quantify, locate, and track virus and toxin aerosols to provide early warning during both light and dark conditions. The solution presented is a remote sensing technology using seeding particles. Seeding particles developed during this program provide specific identification of threat cloud content. When introduced to the threat cloud the seeders will bind specifically to the analyte of interest and upon interrogation from a stand off laser source will fluoresce. The fluorescent signal is detected from a distance using a long-range microscope and collection optics that allow detection of low concentrations of threat aerosols.

  16. Resolving flows around black holes: numerical technique and applications

    CERN Document Server

    Curtis, Michael

    2015-01-01

    Black holes are believed to be one of the key ingredients of galaxy formation models, but it has been notoriously challenging to simulate them due to the very complex physics and large dynamical range of spatial scales involved. Here we address significant shortcomings of a Bondi-Hoyle-like prescription commonly invoked to estimate black hole accretion in cosmological hydrodynamic simulations of galaxy formation. We describe and implement a novel super-Lagrangian refinement scheme to increase, adaptively and 'on the fly', the mass and spatial resolution in targeted regions around the accreting black holes at limited computational cost. While our refinement scheme is generically applicable and flexible, for the purpose of this paper we select the smallest resolvable scales to match black holes' instantaneous Bondi radii, thus effectively resolving Bondi-Hoyle-like accretion in full galaxy formation simulations. This permits us to not only estimate gas properties close to the Bondi radius much more accurately, ...

  17. Deterministic approach for unsteady rarefied flow simulations in complex geometries and its application to gas flows in microsystems

    Science.gov (United States)

    Chigullapalli, Sruti

    Micro-electro-mechanical systems (MEMS) are widely used in automotive, communications and consumer electronics applications with microactuators, micro gyroscopes and microaccelerometers being just a few examples. However, in areas where high reliability is critical, such as in aerospace and defense applications, very few MEMS technologies have been adopted so far. Further development of high frequency microsystems such as resonators, RF MEMS, microturbines and pulsed-detonation microengines require improved understanding of unsteady gas dynamics at the micro scale. Accurate computational simulation of such flows demands new approaches beyond the conventional formulations based on the macroscopic constitutive laws. This is due to the breakdown of the continuum hypothesis in the presence of significant non-equilibrium and rarefaction because of large gradients and small scales, respectively. More generally, the motion of molecules in a gas is described by the kinetic Boltzmann equation which is valid for arbitrary Knudsen numbers. However, due to the multidimensionality of the phase space and the complex non-linearity of the collision term, numerical solution of the Boltzmann equation is challenging for practical problems. In this thesis a fully deterministic, as opposed to a statistical, finite volume based three-dimensional solution of Boltzmann ES-BGK model kinetic equation is formulated to enable simulations of unsteady rarefied flows. The main goal of this research is to develop an unsteady rarefied solver integrated with finite volume method (FVM) solver in MEMOSA (MEMS Overall Simulation Administrator) developed by PRISM: NNSA center for Prediction of Reliability, Integrity and Survivability of Microsystems (PRISM) at Purdue and apply it to study micro-scale gas damping. Formulation and verification of finite volume method for unsteady rarefied flow solver based on Boltzmann-ESBGK equations in arbitrary three-dimensional geometries are presented. The solver is

  18. Multiplexed microbead immunoassays by flow cytometry for molecular profiling: Basic concepts and proteomics applications.

    Science.gov (United States)

    Krishhan, V V; Khan, Imran H; Luciw, Paul A

    2009-01-01

    Flow cytometry was originally established as an automated method for measuring optical or fluorescence characteristics of cells or particles in suspension. With the enormous increase in development of reliable electronics, lasers, micro-fluidics, as well as many advances in immunology and other fields, flow cytometers have become user-friendlier, less-expensive instruments with an increasing importance for both basic research and clinical applications. Conventional uses of flow cytometry include immunophenotyping of blood cells and the analysis of the cell cycle. Importantly, methods for labeling microbeads with unique combinations of fluorescent spectral signatures have made multiplex analysis of soluble analytes (i.e. the ability to detect multiple targets in a single test sample) feasible by flow cytometry. The result is a rapid, high-throughput, sensitive, and reproducible detection technology for a wide range of biomedical applications requiring detection of proteins (in cells and biofluids) and nucleic acids. Thus, novel methods of flow cytometry are becoming important for diagnostic purposes (e.g. identifying multiple clinical biomarkers for a wide range of diseases) as well as for developing novel therapies (e.g. elucidating drug mechanisms and potential toxicities). In addition, flow cytometry for multiplex analysis, coupled with automated sample handling devices, has the potential to significantly enhance proteomics research, particularly analysis of post-translational modifications of proteins, on a large scale. Inherently, flow cytometry methods are strongly rooted in the laws of the physics of optics, fluidics, and electromagnetism. This review article describes principles and early sources of flow cytometry, provides an introduction to the multiplex microbead technology, and discusses its applications and advantages in comparison to other methods. Anticipated future directions, particularly for translational research in medicine, are also discussed.

  19. A model for complex flows of soft glassy materials with application to flows through fixed fiber beds

    KAUST Repository

    Sarkar, Arijit

    2015-11-01

    © 2015 The Society of Rheology. The soft glassy rheology (SGR) model has successfully described the time dependent simple shear rheology of a broad class of complex fluids including foams, concentrated emulsions, colloidal glasses, and solvent-free nanoparticle-organic hybrid materials (NOHMs). The model considers a distribution of mesoscopic fluid elements that hop from trap to trap at a rate which is enhanced by the work done to strain the fluid element. While an SGR fluid has a broad exponential distribution of trap energies, the rheology of NOHMs is better described by a narrower energy distribution and we consider both types of trap energy distributions in this study. We introduce a tensorial version of these models with a hopping rate that depends on the orientation of the element relative to the mean stress field, allowing a range of relative strengths of the extensional and simple shear responses of the fluid. As an application of these models we consider the flow of a soft glassy material through a dilute fixed bed of fibers. The dilute fixed bed exhibits a range of local linear flows which alternate in a chaotic manner with time in a Lagrangian reference frame. It is amenable to an analytical treatment and has been used to characterize the strong flow response of many complex fluids including fiber suspensions, dilute polymer solutions and emulsions. We show that the accumulated strain in the fluid elements has an abrupt nonlinear growth at a Deborah number of order one in a manner similar to that observed for polymer solutions. The exponential dependence of the hopping rate on strain leads to a fluid element deformation that grows logarithmically with Deborah number at high Deborah numbers. SGR fluids having a broad range of trap energies flowing through fixed beds can exhibit a range of rheological behaviors at small Deborah numbers ranging from a yield stress, to a power law response and finally to Newtonian behavior.

  20. Application of essentially nonoscillatory methods to aeroacoustic flow problems

    Science.gov (United States)

    Atkins, Harold L.

    1995-01-01

    A finite-difference essentially nonoscillatory (ENO) method has been applied to several of the problems prescribed for the workshop sponsored jointly by the Institute for Computer Applications in Science and Engineering and by NASA Langley Research Center entitled 'Benchmark Problems in Computational Aeroacoustics'. The workshop focused on computational challenges specific to aeroacoustics. Among these are long-distance propagation of a short-wavelength disturbance, propagation of small-amplitude disturbances, and nonreflective boundary conditions. The shock capturing-capability inherent to the ENO method effectively eliminates oscillations near shock waves without the need to add and tune dissipation or filter terms. The method-of-lines approach allows the temporal and spatial operators to be chosen separately in accordance with the demands of a particular problem. The ENO method was robust and accurate for all problems in which the propagating wave was resolved with 8 or more points per wavelength. The finite-wave-model boundary condition, a local nonlinear acoustic boundary condition, performed well for the one-dimensional problems. The buffer-domain approach performed well for the two-dimensional test problem. The amplitude of nonphysical reflections were less than 1 percent of the exiting wave's amplitude.

  1. On the Hamiltonian approach: Applications to geophysical flows

    Directory of Open Access Journals (Sweden)

    V. Goncharov

    1998-01-01

    Full Text Available This paper presents developments of the Harniltonian Approach to problems of fluid dynamics, and also considers some specific applications of the general method to hydrodynamical models. Nonlinear gauge transformations are found to result in a reduction to a minimum number of degrees of freedom, i.e. the number of pairs of canonically conjugated variables used in a given hydrodynamical system. It is shown that any conservative hydrodynamic model with additional fields which are in involution may be always reduced to the canonical Hamiltonian system with three degrees of freedom only. These gauge transformations are associated with the law of helicity conservation. Constraints imposed on the corresponding Clebsch representation are determined for some particular cases, such as, for example. when fluid motions develop in the absence of helicity. For a long time the process of the introduction of canonical variables into hydrodynamics has remained more of an intuitive foresight than a logical finding. The special attention is allocated to the problem of the elaboration of the corresponding regular procedure. The Harniltonian Approach is applied to geophysical models including incompressible (3D and 2D fluid motion models in curvilinear and lagrangian coordinates. The problems of the canonical description of the Rossby waves on a rotating sphere and of the evolution of a system consisting of N singular vortices are investigated.

  2. Disperse two-phase flows, with applications to geophysical problems

    CERN Document Server

    Berselli, Luigi Carlo; Iliescu, Traian

    2014-01-01

    In this paper we study the motion of a fluid with several dispersed particles whose concentration is very small (smaller than $10^{-3}$), with possible applications to problems coming from geophysics, meteorology, and oceanography. We consider a very dilute suspension of heavy particles in a quasi-incompressible fluid (low Mach number). In our case the Stokes number is small and --as pointed out in the theory of multiphase turbulence-- we can use an Eulerian model instead of a Lagrangian one. The assumption of low concentration allows us to disregard particle--particle interactions, but we take into account the effect of particles on the fluid (two-way coupling). In this way we can study the physical effect of particle inertia (and not only passive tracers), with a model similar to the Boussinesq equations. The resulting model is used in both direct numerical simulations and large eddy simulations of a dam-break (lock-exchange) problem, which is a well-known academic test case. Keywords: Dilute suspensions, E...

  3. Frequency Comb Assisted Broadband Precision Spectroscopy with Cascaded Diode Lasers

    CERN Document Server

    Liu, Junqiu; Pfeiffer, Martin H P; Kordts, Arne; Kamel, Ayman N; Guo, Hairun; Geiselmann, Michael; Kippenberg, Tobias J

    2016-01-01

    Frequency comb assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this letter we present a novel method using cascaded frequency agile diode lasers, which allows extending the measurement bandwidth to 37.4 THz (1355 to 1630 nm) at MHz resolution with scanning speeds above 1 THz/s. It is demonstrated as a useful tool to characterize a broadband spectrum for molecular spectroscopy and in particular it enables to characterize the dispersion of integrated microresonators up to the fourth order.

  4. [Application of thermal dissipation probe in the study of Bambusa chungii sap flow].

    Science.gov (United States)

    Zhao, Ping; Mei, Ting-Ting; Ni, Guang-Yan; Yu, Meng-Hao; Zeng, Xiao-Ping

    2012-04-01

    Based on the validation of Granier's empirical formula for calculating tree stem sap flux density, a comparative study was conducted on the measurement of Bambusa chungi sap flow by using different lengths of thermal dissipation probe (TDP), aimed to approach the applicability of TDP in measuring the sap flow of B. chungii. The difference in the daily change of the sap flow between B. chungii and nearby growing Schima superb was also analyzed. Because of the thinner bamboo wall and the heterogeneous anatomy, the sap flux density of B. chungii measured by 10 mm long probe could be underestimated, but that measured by 8 and 5 mm long probes could be relatively accurate. The comparison of the sap flow between B. chungii and nearby growing S. superba revealed that both the mean sap flux density and its daily change pattern' s skewness of B. chungii were higher than those of S. superba, but the nighttime sap flow of B. chungii was less than that of S. superba, indicating that the water recharge of B. chungii during nighttime was less active than that of S. superba. It was suggested that using TDP to investigate the sap flow of bamboo would be feasible, but careful calibration would be required before the TDP was put into application on different bamboo species.

  5. 100 years of the physics of diodes

    Science.gov (United States)

    Zhang, Peng; Valfells, Ágúst; Ang, L. K.; Luginsland, J. W.; Lau, Y. Y.

    2017-03-01

    The Child-Langmuir Law (CL), discovered a century ago, gives the maximum current that can be transported across a planar diode in the steady state. As a quintessential example of the impact of space charge shielding near a charged surface, it is central to the studies of high current diodes, such as high power microwave sources, vacuum microelectronics, electron and ion sources, and high current drivers used in high energy density physics experiments. CL remains a touchstone of fundamental sheath physics, including contemporary studies of nanoscale quantum diodes and nano gap based plasmonic devices. Its solid state analog is the Mott-Gurney law, governing the maximum charge injection in solids, such as organic materials and other dielectrics, which is important to energy devices, such as solar cells and light emitting diodes. This paper reviews the important advances in the physics of diodes since the discovery of CL, including virtual cathode formation and extension of CL to multiple dimensions, to the quantum regime, and to ultrafast processes. We review the influence of magnetic fields, multiple species in bipolar flow, electromagnetic and time dependent effects in both short pulse and high frequency THz limits, and single electron regimes. Transitions from various emission mechanisms (thermionic-, field-, and photoemission) to the space charge limited state (CL) will be addressed, especially highlighting the important simulation and experimental developments in selected contemporary areas of study. We stress the fundamental physical links between the physics of beams to limiting currents in other areas, such as low temperature plasmas, laser plasmas, and space propulsion.

  6. Application of Heterogeneous Copper Catalyst in a Continuous Flow Process: Dehydrogenation of Cyclohexanol

    Science.gov (United States)

    Glin´ski, Marek; Ulkowska, Urszula; Iwanek, Ewa

    2016-01-01

    In this laboratory experiment, the synthesis of a supported solid catalyst (Cu/SiO2) and its application in the dehydrogenation of cyclohexanol performed under flow conditions was studied. The experiment was planned for a group of two or three students for two 6 h long sessions. The copper catalyst was synthesized using incipient wetness…

  7. Synthesis of Biochemical Applications on Flow-Based Microfluidic Biochips using Constraint Programming

    DEFF Research Database (Denmark)

    Minhass, Wajid Hassan; Pop, Paul; Madsen, Jan

    2012-01-01

    . By combining several microvalves, more complex units, such as micropumps, switches, mixers, and multiplexers, can be built. We propose a constraint programming (CP) based approach for the synthesis of biochemical applications on flow-based microfluidic biochips. We use a sequencing graph to model...

  8. Finite element methods in incompressible, adiabatic, and compressible flows from fundamental concepts to applications

    CERN Document Server

    Kawahara, Mutsuto

    2016-01-01

    This book focuses on the finite element method in fluid flows. It is targeted at researchers, from those just starting out up to practitioners with some experience. Part I is devoted to the beginners who are already familiar with elementary calculus. Precise concepts of the finite element method remitted in the field of analysis of fluid flow are stated, starting with spring structures, which are most suitable to show the concepts of superposition/assembling. Pipeline system and potential flow sections show the linear problem. The advection–diffusion section presents the time-dependent problem; mixed interpolation is explained using creeping flows, and elementary computer programs by FORTRAN are included. Part II provides information on recent computational methods and their applications to practical problems. Theories of Streamline-Upwind/Petrov–Galerkin (SUPG) formulation, characteristic formulation, and Arbitrary Lagrangian–Eulerian (ALE) formulation and others are presented with practical results so...

  9. Study on the application of semiconductor light emitting diode and its lighting%探讨半导体发光二极管及其照明的应用

    Institute of Scientific and Technical Information of China (English)

    汪磊

    2016-01-01

    At present,with the rapid development of China's socialist market economy,people's living standards and quality of life continues to improve,so the cause of lighting proposed higher requirements, the semiconductor light-emitting diode has excellent performance in energy conservation and environmental protection,use for a long time,with good efficiency,therefore has been widely used in indoor and outdoor lighting.In this paper,through the analysis of light emitting diode principle,to discuss the application of the lighting.%现阶段,随着我国社会主义市场经济飞速发展,人们生活水平和生活质量不断提高,因此对照明事业提出了更高的要求,半导体发光二极管具备了良好的节能、环保性能,使用时间较长,具有良好的高效性,因此而被大量使用于室内外的照明当中,本文通过对发光二极管原理进行分析,探讨其照明的应用。

  10. Avalanche robustness of SiC Schottky diode

    OpenAIRE

    Dchar, Ilyas; Buttay, Cyril; Morel, Hervé

    2016-01-01

    International audience; Reliability is one of the key issues for the application of Silicon carbide (SiC) diode in high power conversion systems. For instance, in high voltage direct current (HVDC) converters, the devices can be submitted to high voltage transients which yield to avalanche. This paper presents the experimental evaluation of SiC diodes submitted to avalanche, and shows that the energy dissipation in the device can increase quickly and will not be uniformly distributed across t...

  11. Determination of band offsets at strained NiO and MgO heterojunction for MgO as an interlayer in heterojunction light emitting diode applications

    Science.gov (United States)

    Singh, S. D.; Nand, Mangla; Ajimsha, R. S.; Upadhyay, Anuj; Kamparath, Rajiv; Mukherjee, C.; Misra, P.; Sinha, A. K.; Jha, S. N.; Ganguli, Tapas

    2016-12-01

    Valence band offset of 2.3 ± 0.4 eV at strained NiO/MgO heterojunction is determined from photoelectron spectroscopy (PES) measurements. The determined value of valence band offset is larger than that is predicted from first principle calculations, but is in corroboration with that obtained from band transitivity rule. Our PES result indicates a larger value of the valence band offset at strained NiO/MgO heterojunction and can be used to predict accurately carrier transport and electroluminescence mechanisms for n-ZnO/MgO/p-NiO and p-NiO/MgO/n-GaN heterojunction light emitting diodes.

  12. Application of spherical diodes to size dose in means of photons of megavoltage; Aplicacion de diodos esfericos a la medida de dosis en hace de fotones de megavoltaje

    Energy Technology Data Exchange (ETDEWEB)

    Barbes, B.; Azcona, J. D.; Burguete, J.; Marti-Climent, J. M.

    2013-07-01

    We studied the ability of a spherical diode commercial, designed originally as a photovoltaic cell, to measure doses of beams of photons of nominal energies from 6 to 15 MV from a linear accelerator of therapeutic use. Previously it had proven its capacity for energy used in brachytherapy (20-30 keV) measures. We studied their angular response degradation with previous irradiance and its reliability for measures of factors of countryside on apertures from 2x2cm until 16x16cm. We check your over-response to scattered photons of low energy, produced in large fields, and the possibility of correcting this effect with a shield. (Author)

  13. Improved Light Output Power of Chemically Transferred InGaN/GaN Light-Emitting Diodes for Flexible Optoelectronic Applications

    Directory of Open Access Journals (Sweden)

    Ho-Jun Lee

    2015-01-01

    Full Text Available Recent needs of semiconductor lighting sources have pursued diverse functionalities such as flexibility and transparency under high quantum efficiency. Inorganic/organic hybrid light-emitting diodes (LEDs are one way to meet these requirements. Here, we report on flexible III-nitride-based LEDs and the improvement of their electrical and optical properties. To realize high light emission power and stable current operation, high-quality epitaxy and elaborate chip processing were performed. The fabricated flexible LEDs showed over threefold optical output power compared to normal LEDs on Si and had comparable forward voltage and series resistances.

  14. The angular dependence of a 2-dimensional diode array and the feasibility of its application in verifying the composite dose distribution of intensity-modulated radiation therapy.

    Science.gov (United States)

    Li, Qi-Lin; Deng, Xiao-Wu; Chen, Li-Xin; Huang, Xiao-Yan; Huang, Shao-Min

    2010-06-01

    The planning dose distribution of intensity-modulated radiation therapy (IMRT) has to be verified before clinical implementation. The commonly used verification method is to measure the beam fluency at 0 degree gantry angle with a 2-dimensional (2D) detector array, but not the composite dose distribution of the real delivery in the planned gantry angles. This study was to investigate the angular dependence of a 2D diode array (2D array) and the feasibility of using it to verify the composite dose distribution of IMRT. Angular response of the central detector in the 2D array was measured for 6 MV X-ray, 10 cmx10 cm field and 100 cm source axis distance (SAD) in different depths. With the beam incidence angle of 0-60 degrees, at intervals of 10 degrees, and inherent buildup of the 2D array (2 g/cm2), the array was irradiated and the readings of the central diode were compared with the measurement of thimble ionization chamber. Using a combined 30 cmx30 cmx30 cm phantom which consisted of solid water slabs on top and underlying the 2D array, with the diode detectors placed at 8 g/cm2 depth, measurements were taken for beam angles of 0 degrees-180 degrees at intervals of 10 degrees and compared with the calculation of treatment planning system (TPS) that pre-verified with ion chamber measuring. Differences between the array detector and thimble chamber measurements were greater than 1% and 3.5% when the beam angle was larger than 30 degrees and 60 degrees, respectively. The measurements in the combined phantom were different from the calculation as high as 20% for 90 degrees beam angle, 2% at 90 degrees+/-5 degrees and less than 1% for all the other beam angles. The 2D diode array is capable of being used in composite dose verification of IMRT when the beam angles of 90 degrees+/-5 degrees and 270 degrees+/-5 degrees are avoided.

  15. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.

    2015-01-01

    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface

  16. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.

    2015-01-01

    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface heatin

  17. Single-molecule diodes with high rectification ratios through environmental control.

    Science.gov (United States)

    Capozzi, Brian; Xia, Jianlong; Adak, Olgun; Dell, Emma J; Liu, Zhen-Fei; Taylor, Jeffrey C; Neaton, Jeffrey B; Campos, Luis M; Venkataraman, Latha

    2015-06-01

    Molecular electronics aims to miniaturize electronic devices by using subnanometre-scale active components. A single-molecule diode, a circuit element that directs current flow, was first proposed more than 40 years ago and consisted of an asymmetric molecule comprising a donor-bridge-acceptor architecture to mimic a semiconductor p-n junction. Several single-molecule diodes have since been realized in junctions featuring asymmetric molecular backbones, molecule-electrode linkers or electrode materials. Despite these advances, molecular diodes have had limited potential for applications due to their low conductance, low rectification ratios, extreme sensitivity to the junction structure and high operating voltages. Here, we demonstrate a powerful approach to induce current rectification in symmetric single-molecule junctions using two electrodes of the same metal, but breaking symmetry by exposing considerably different electrode areas to an ionic solution. This allows us to control the junction's electrostatic environment in an asymmetric fashion by simply changing the bias polarity. With this method, we reliably and reproducibly achieve rectification ratios in excess of 200 at voltages as low as 370 mV using a symmetric oligomer of thiophene-1,1-dioxide. By taking advantage of the changes in the junction environment induced by the presence of an ionic solution, this method provides a general route for tuning nonlinear nanoscale device phenomena, which could potentially be applied in systems beyond single-molecule junctions.

  18. A programmable and portable NMES device for drop foot correction and blood flow assist applications.

    Science.gov (United States)

    Breen, Paul P; Corley, Gavin J; O'Keeffe, Derek T; Conway, Richard; Olaighin, Gearóid

    2009-04-01

    The Duo-STIM, a new, programmable and portable neuromuscular stimulation system for drop foot correction and blood flow assist applications is presented. The system consists of a programmer unit and a portable, programmable stimulator unit. The portable stimulator features fully programmable, sensor-controlled, constant-voltage, dual-channel stimulation and accommodates a range of customized stimulation profiles. Trapezoidal and free-form adaptive stimulation intensity envelope algorithms are provided for drop foot correction applications, while time dependent and activity dependent algorithms are provided for blood flow assist applications. A variety of sensor types can be used with the portable unit, including force sensitive resistor-based foot switches and MEMS-based accelerometer and gyroscope devices. The paper provides a detailed description of the hardware and block-level system design for both units. The programming and operating procedures for the system are also presented. Finally, functional bench test results for the system are presented.

  19. Wavelength beam combining of a 980-nm tapered diode laser bar in an external cavity

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup Nielsen, Birgitte

    2010-01-01

    High power diode lasers are used in a large number of applications. A limiting factor for more widespread use of broad area lasers is the poor beam quality. Gain guided tapered diode lasers are ideal candidates for industrial applications that demands watt level output power with good beam quality...

  20. Development of Smoothed Particle Hydrodynamics for Flow in Complex Geometries and Application of Open Source Software for the Simulation of Turbulent Flow

    DEFF Research Database (Denmark)

    Obeidat, Anas Hassan MohD

    engines removes combustion gases from the engine cylinder and fills up the cylinder with the fresh air charge for the next cycle. Understanding the scavenging flow is crucial for the development of such engines, since it a˙ects fuel consumption, engine cooling and production of pollutants. We consider......Turbulence modelling is a key issue in many industrial application, as the com-putational power of direct numerical simulation (DNS) is insuÿcient to deal with complex flow structures with high Reynolds number. Also in Industrial applications often involve turbulent flow in complex geometries. Thus...

  1. "Diode Pumped Solid State Lasers At 2 And 3 µm"

    Science.gov (United States)

    Esterowitz, Leon

    1988-06-01

    The most attractive alternative to flashlamp pumping of solid state lasers is the diode laser. In the past two decades numerous laboratory devices have been assembled which incorporated single diode lasers, small laser diode arrays or LED's for pumping of Nd:YAG, Nd:glass and a host of other Nd lasers. The low power output, low packaging density, and extremely high cost of diode lasers prevented any serious applications for laser pumping in the past. The reason for the continued interest in this area stems from the potential dramatic increase in system efficiency and component lifetime, and reduction of thermal load of the solid-state laser material. The latter not only will reduce thereto-optic effects and therefore lead to better beam quality but also will enable an increase in pulse repetition frequency. The attractive operating parameters combined with low voltage operation and the compactness of an all solid-state laser system have a potential high payoff. The high pumping efficiency compared to flashlamps stems from the good spectral match between the laser diode emission and the rare earth activator absorption bands. A significant advantage of laser diode pumping compared to arc lamps is system lifetime and reliability. Laser diode arrays have exhibited lifetimes on the order of 10,000 hours in cw operation and 109 shots in the pulsed mode. Flashlamp life is on the order of 107 shots, and about 200 hours for cw operation. In addition, the high pump flux combined with a substantial UV content in lamp pumped systems causes material degradation in the pump cavity and in the coolant. Such problems are virtually eliminated with laser diode pump sources. The absence of high voltage pulses, high temperatures and UV radiation encountered with arc lamps leads to much more benign operating features for solid state laser systems employing laser diode pumps. Laser diode technology dates back to 1962 when laser action in GaAs diodes was first demonstrated. However, it

  2. Optimization of the AC-gradient method for velocity profile measurement and application to slow flow

    Science.gov (United States)

    Kartäusch, Ralf; Helluy, Xavier; Jakob, Peter Michael; Fidler, Florian

    2014-11-01

    This work presents a spectroscopic method to measure slow flow. Within a single shot the velocity distribution is acquired. This allows distinguishing rapidly between single velocities within the sampled volume with a high sensitivity. The technique is based on signal acquisition in the presence of a periodic gradient and a train of refocussing RF pulses. The theoretical model for trapezoidal bipolar pulse shaped gradients under consideration of diffusion and the outflow effect is introduced. A phase correction technique is presented that improves the spectral accuracy. Therefore, flow phantom measurements are used to validate the new sequence and the simulation based on the theoretical model. It was demonstrated that accurate parabolic flow profiles can be acquired and flow variations below 200 μm/s can be detected. Three post-processing methods that eliminate static background signal are also presented for applications in which static background signal dominates. Finally, this technique is applied to flow measurement of a small alder tree demonstrating a typical application of in vivo plant measurements.

  3. An Analysis of the Equivalent Resistance of PIN Diodes at Microwave Frequencies

    Institute of Scientific and Technical Information of China (English)

    YANG Guo-yu; SONG Kai-jun; MAO Rui-jie; LU Shi-qiang

    2004-01-01

    The forward bias equivalent resistance of PIN diodes, an important parameter in applications, is usually measured at lower frequencies. But in fact, due to skin effect the effective conduction area of the region I of a PIN diode decreases as the frequency increases. In this paper, the affection of skin effect to forward bias equivalent resistance is considered and an analytic expression of the equivalent resistance of the region I is presented. In result, the forward bias resistance ora PIN diode at microwave frequencies is much higher than that at DC and low frequencies. It is necessary, therefore,to consider the skin effect of PIN diodes in high frequency applications.

  4. FastFlow: Efficient Parallel Streaming Applications on Multi-core

    CERN Document Server

    Aldinucci, Marco; Meneghin, Massimiliano

    2009-01-01

    Shared memory multiprocessors come back to popularity thanks to rapid spreading of commodity multi-core architectures. As ever, shared memory programs are fairly easy to write and quite hard to optimise; providing multi-core programmers with optimising tools and programming frameworks is a nowadays challenge. Few efforts have been done to support effective streaming applications on these architectures. In this paper we introduce FastFlow, a low-level programming framework based on lock-free queues explicitly designed to support high-level languages for streaming applications. We compare FastFlow with state-of-the-art programming frameworks such as Cilk, OpenMP, and Intel TBB. We experimentally demonstrate that FastFlow is always more efficient than all of them in a set of micro-benchmarks and on a real world application; the speedup edge of FastFlow over other solutions might be bold for fine grain tasks, as an example +35% on OpenMP, +226% on Cilk, +96% on TBB for the alignment of protein P01111 against UniP...

  5. Contactless Inductive Flow Tomography: Brief History and Recent Developments in Its Application to Continuous Casting

    Directory of Open Access Journals (Sweden)

    Matthias Ratajczak

    2014-01-01

    Full Text Available The contactless inductive flow tomography (CIFT aims at reconstructing the velocity field of electrically conducting fluids, with special focus on applications in metallurgy and crystal growth technologies. The method relies on the induction of secondary magnetic fields if the moving fluid is exposed to a primary magnetic field. The theoretical foundation of the method is delineated, and some early experiments on the reconstruction of the three-dimensional flow in a cylinder are sketched. Then, the recent efforts to apply CIFT to various model problems in connection with the continuous casting of steel are summarized.

  6. Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows

    Science.gov (United States)

    Sammy, Mo

    2010-01-01

    Active flow control is often used to manipulate flow instabilities to achieve a desired goal (e.g. prevent separation, enhance mixing, reduce noise, etc.). Instability frequencies normally scale with flow velocity scale and inversely with flow length scale (U/l). In a laboratory setting for such flow experiments, U is high, but l is low, resulting in high instability frequency. In addition, high momentum and high background noise & turbulence in the flow necessitate high amplitude actuation. Developing a high amplitude and high frequency actuator is a major challenge. Ironically, these requirements ease up in application (but other issues arise).

  7. Applications of Low Density Flow Techniques and Catalytic Recombination at the Johnson Space Center

    Science.gov (United States)

    Scott, Carl D.

    2000-01-01

    The talk presents a brief background on defInitions of catalysis and effects associated with chemically nonequilibrium and low-density flows of aerospace interest. Applications of catalytic recombination on surfaces in dissociated flow are given, including aero heating on reentry spacecraft thermal protection surfaces and reflection of plume flow on pressure distributions associated with the space station. Examples include aero heating predictions for the X-38 test vehicle, the inlet of a proposed gas-sampling probe used in high enthalpy test facilities, and a parabolic body at angle of attack. The effect of accommodation coefficients on thruster induced pressure distributions is also included. Examples of tools used include simple aero heating formulas based on boundary layer solutions, an engineering approximation that uses axisymmetric viscous shock layer flow to simulate full three dimensional flow, full computational fluid dynamics, and direct simulation Monte-Carlo calculations. Methods of determining catalytic recombination rates in arc jet flow are discus ed. An area of catalysis not fully understood is the formation of single-wall carbon nanotubes (SWNT) with gas phase or nano-size metal particles. The Johnson Space Center is making SWNTs using both a laser ablation technique and an electric arc vaporization technique.

  8. Contactless inductive flow tomography: basic principles and first applications in the experimental modelling of continuous casting

    Science.gov (United States)

    Stefani, F.; Eckert, S.; Ratajczak, M.; Timmel, K.; Wondrak, T.

    2016-07-01

    Contactless inductive flow tomography (CIFT) aims at reconstructing the flow structure of a liquid metal from the magnetic fields measured at various positions outside the fluid body which are induced by the flow under the influence of one or multiple applied magnetic fields. We recap the basic mathematical principles of CIFT and the results of an experiment in which the propeller-driven three-dimensional flow in a cylindrical had been reconstructed. We also summarize the recent activities to utilize CIFT in various problems connected with the experimental simulation of the continuous casting process. These include flow reconstructions in single-phase and two-phase flow problems in the Mini-LIMMCAST model of slab-casting, studies of the specific effects of an electromagnetic stirrer attached to the Submerged Entry Nozzle (SEN), as well as first successful applications of CIFT on the background of a strong electromagnetic brake field. We conclude by discussing some remaining obstacles for the deployment of CIFT in a real caster.

  9. Asymmetric magnetic reconnection with a flow shear and applications to the magnetopause

    Science.gov (United States)

    Doss, C. E.; Komar, C. M.; Cassak, P. A.; Wilder, F. D.; Eriksson, S.; Drake, J. F.

    2015-09-01

    smaller mass flux into the dissipation region contributes a smaller mass to the dissipation region, so the effect of its flow on opposing the release of energy by the reconnected magnetic fields is diminished and the reconnection is not suppressed to the extent previously thought. The results compare favorably with an observation of reconnection at Earth's polar cusps during a period of northward interplanetary magnetic field, where reconnection occurs despite the magnetosheath flow speed being more than twice the magnetosheath Alfvén speed, the previously proposed suppression condition. These results are expected to be of broad importance for magnetospheric physics of Earth and other planets; particular applications are discussed.

  10. Application Oriented Flow Routing Algorithm for VoIP Overlay Networks

    Science.gov (United States)

    Wipusitwarakun, Komwut; Chimmanee, Sanon

    Overlay networks which are dynamically created over underlying IP networks are becoming widely used for delivering multimedia contents since they can provide several additional user-definable services. Multiple overlay paths between a source-destination overlay node pair are designed to improve service robustness against failures and bandwidth fluctuation of the underlying networks. Multimedia traffic can be distributed over those multiple paths in order to maximize paths' utilization and to increase application throughputs. Most of flow-based routing algorithms consider only common metrics such as paths' bandwidth or delay, which may be effective for data applications but not for real-time applications such as Voice over IP (VoIP), in which different levels of such performance metrics may give the same level of the performance experienced by end users. This paper focuses on such VoIP overlay networks and proposes a novel alternative path based flow routing algorithm using an application-specific traffic metric, i.e. “VoIP Path Capacity (VPCap), ” to calculate the maximum number of QoS satisfied VoIP flows which may be distributed over each available overlay path at a moment. The simulation results proved that more QoS-satisfied VoIP sessions can be established over the same multiple overlay paths, comparing to traditional approaches.

  11. Development of an Efficient Meso- scale Multi-phase Flow Solver in Nuclear Applications

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Taehun [City Univ. (CUNY), NY (United States)

    2015-10-20

    The proposed research aims at formulating a predictive high-order Lattice Boltzmann Equation for multi-phase flows relevant to nuclear energy related application - namely, saturated and sub-cooled boiling in reactors, and liquid- liquid mixing and extraction for fuel cycle separation. An efficient flow solver will be developed based on the Finite Element based Lattice Boltzmann Method (FE- LBM), accounting for phase-change heat transfer and capable of treating multiple phases over length scales from the submicron to the meter. A thermal LBM will be developed in order to handle adjustable Prandtl number, arbitrary specific heat ratio, a wide range of temperature variations, better numerical stability during liquid-vapor phase change, and full thermo-hydrodynamic consistency. Two-phase FE-LBM will be extended to liquid–liquid–gas multi-phase flows for application to high-fidelity simulations building up from the meso-scale up to the equipment sub-component scale. While several relevant applications exist, the initial applications for demonstration of the efficient methods to be developed as part of this project include numerical investigations of Critical Heat Flux (CHF) phenomena in nuclear reactor fuel bundles, and liquid-liquid mixing and interfacial area generation for liquid-liquid separations. In addition, targeted experiments will be conducted for validation of this advanced multi-phase model.

  12. Hyperchaos via X-Diode

    DEFF Research Database (Denmark)

    Lindberg, Erik; Tamasevicius, A.; Cenys, A.

    1998-01-01

    A Chaos diode (X-diode) with a hysteric current-voltage characteristic has been used to generate hyperchaotic oscillations characterized with multiple positive Lyapunov exponents. The hyperchaotic oscillators comprise a X-diode in parallel with an M'th order LC loop (M.GE.4). Numerical simulations...... and hardware experiments have beeen performed. An appropriate mathematical model is provided and is used to calculate the Lyapunov exponents. Synchronization properties have been investigated....

  13. Zigzag and Helical AlN Layer Prepared by Glancing Angle Deposition and Its Application as a Buffer Layer in a GaN-Based Light-Emitting Diode

    Directory of Open Access Journals (Sweden)

    Lung-Chien Chen

    2012-01-01

    Full Text Available This study investigates an aluminum nitride (AlN nanorod structure sputtered by glancing angle deposition (GLAD and its application as a buffer layer for GaN-based light-emitting diodes (LEDs that are fabricated on sapphire substrates. The ray tracing method is adopted with a three-dimensional model in TracePro software. Simulation results indicate that the zigzag AlN nanorod structure is an optimal buffer layer in a GaN-based LED. Furthermore, the light output power of a GaN-based LED with a zigzag AlN nanorod structure improves to as much as 28.6% at a forward current of 20 mA over that of the GaN-based LED with a normal AlN buffer layer.

  14. Luminescence properties of blue La1-xCexAl(Si6-zAlz)(N10-zOz) (z˜1) oxynitride phosphors and their application in white light-emitting diode

    Science.gov (United States)

    Takahashi, Kohsei; Hirosaki, Naoto; Xie, Rong-Jun; Harada, Masamichi; Yoshimura, Ken-ichi; Tomomura, Yoshitaka

    2007-08-01

    This letter reports blue oxynitride phosphors of La1-xCexAl(Si6-zAlz)(N10-zOz) (z˜1) (termed JEM crystal phase) and their application for the white light-emitting diodes (LEDs). The JEM phosphor can be excited by 405nm light efficiently, and its spectrum can be tuned widely by changing the Ce concentration. The emission spectrum of this phosphor is as wide as 110nm in full width at half maximum, which is convenient to solid state lighting. The preparation of white LED was attempted by using a 405nm InGaN chip and oxynitride phosphors in this work. High color rendering index >95 was achieved in white LED with various correlated color temperatures, indicating the suitability of the JEM phosphor in solid-state lightings.

  15. Naturally-Forced Slug Flow Expander for Application in a Waste-Heat Recovery Cycle

    Directory of Open Access Journals (Sweden)

    Ben de Witt

    2014-11-01

    Full Text Available This paper investigates a slug-flow expander (SFE for conversion of high-pressure gas/vapor into kinetic energy of liquid slugs. The energy transfer from high-pressure to kinetic energy is quantified using thrust plate measurements. Non-dimensional thrust data is used to quantify performance by normalizing measured thrust by thrust for the same water flow rate at zero air flow rate. A total of 13 expander configurations are investigated and geometries with the shortest cavity length and the smallest exit diameter are found to result in the largest non-dimensional thrust increase. Results show that thrust augmentation increases with the initiation of slug flow in the SFE. The analysis performed on the normalized thrust readings suggested that as the water and air flow were increased to critical conditions, the liquid slugs produced by the SFE augmented the thrust measurements. The final performance evaluation was based on linear regression of the normalized thrust measurements where slug flow was generated for each SFE architecture. Greater magnitudes of the slope from the linear regression indicated the propensity of the SFE to augment thrust. This analysis confirmed that for the SFE configurations over the range of values investigated, the SFE increased thrust up to three times its original value at no air flow. Given the inherent multiphase nature of the slug-flow expander, application to systems involving expansion of wetting fluids (water as part of a waste-heat recovery system or air with water droplet formation (as part of a compressed-air energy storage system could be considered.

  16. High order methods for incompressible fluid flow: Application to moving boundary problems

    Energy Technology Data Exchange (ETDEWEB)

    Bjoentegaard, Tormod

    2008-04-15

    Fluid flows with moving boundaries are encountered in a large number of real life situations, with two such types being fluid-structure interaction and free-surface flows. Fluid-structure phenomena are for instance apparent in many hydrodynamic applications; wave effects on offshore structures, sloshing and fluid induced vibrations, and aeroelasticity; flutter and dynamic response. Free-surface flows can be considered as a special case of a fluid-fluid interaction where one of the fluids are practically inviscid, such as air. This type of flows arise in many disciplines such as marine hydrodynamics, chemical engineering, material processing, and geophysics. The driving forces for free-surface flows may be of large scale such as gravity or inertial forces, or forces due to surface tension which operate on a much smaller scale. Free-surface flows with surface tension as a driving mechanism include the flow of bubbles and droplets, and the evolution of capillary waves. In this work we consider incompressible fluid flow, which are governed by the incompressible Navier-Stokes equations. There are several challenges when simulating moving boundary problems numerically, and these include - Spatial discretization - Temporal discretization - Imposition of boundary conditions - Solution strategy for the linear equations. These are some of the issues which will be addressed in this introduction. We will first formulate the problem in the arbitrary Lagrangian-Eulerian framework, and introduce the weak formulation of the problem. Next, we discuss the spatial and temporal discretization before we move to the imposition of surface tension boundary conditions. In the final section we discuss the solution of the resulting linear system of equations. (Author). refs., figs., tabs

  17. On rating curve variability in presence of movable bed and unsteady flow. Applications to Tuscan rivers.

    Science.gov (United States)

    Minatti, Lorenzo; Nicoletta De Cicco, Pina; Paris, Enio

    2014-05-01

    In common engineering practice, rating curves are obtained from direct stage-discharge measurements or, more often, from stage measurements coupled with flow simulations. The present work mainly focuses on the latter technique, where stage-measuring gauges are usually installed on bridges with flow conditions likely to be influenced by local geometry constraints. In such cases, backwater flow and flow transition to supercritical state may occur, influencing sediment transport capacity and triggering more intense changes in river morphology. The unsteadiness of the flow hydrograph may play an important role too, according to the velocity of its rising and falling limbs. Nevertheless, the simulations conducted to build a rating curve are often carried out with steady flow and fixed bed conditions where the afore-mentioned effects are not taken into account at all. Numerical simulations with mobile bed and different unsteady flow conditions have been conducted on some real case studies in the rivers of Tuscany (Italy), in order to assess how rating curves change with respect to the "standard" one (that is, the classical steady flow rating curve). A 1D finite volume numerical model (REMo, River Evolution Modeler) has been employed for the simulations. The model solves the 1D Shallow Water equations coupled with the sediments continuity equation in composite channels, where the overbanks are treated with fixed bed conditions while the main channel can either aggrade or be scoured. The model employs an explicit scheme with 2nd order accuracy in both space and time: this allows the correct handling of moderately stiff source terms via a local corrector step. Such capability is very important for the applications of the present work as it allows the modelling of abrupt contractions and jumps in bed bottom elevations which often occur near bridges. The outcomes of the simulations are critically analyzed in order to provide a first insight on the conditions inducing

  18. VISUALIZATION METHODS OF VORTICAL FLOWS IN COMPUTATIONAL FLUID DYNAMICS AND THEIR APPLICATIONS

    Directory of Open Access Journals (Sweden)

    K. N. Volkov

    2014-05-01

    Full Text Available The paper deals with conceptions and methods for visual representation of research numerical results in the problems of fluid mechanics and gas. The three-dimensional nature of unsteady flow being simulated creates significant difficulties for the visual representation of results. It complicates control and understanding of numerical data, and exchange and processing of obtained information about the flow field. Approaches to vortical flows visualization with the usage of gradients of primary and secondary scalar and vector fields are discussed. An overview of visualization techniques for vortical flows using different definitions of the vortex and its identification criteria is given. Visualization examples for some solutions of gas dynamics problems related to calculations of jets and cavity flows are presented. Ideas of the vortical structure of the free non-isothermal jet and the formation of coherent vortex structures in the mixing layer are developed. Analysis of formation patterns for spatial flows inside large-scale vortical structures within the enclosed space of the cubic lid-driven cavity is performed. The singular points of the vortex flow in a cubic lid-driven cavity are found based on the results of numerical simulation; their type and location are identified depending on the Reynolds number. Calculations are performed with fine meshes and modern approaches to the simulation of vortical flows (direct numerical simulation and large-eddy simulation. Paradigm of graphical programming and COVISE virtual environment are used for the visual representation of computational results. Application that implements the visualization of the problem is represented as a network which links are modules and each of them is designed to solve a case-specific problem. Interaction between modules is carried out by the input and output ports (data receipt and data transfer giving the possibility to use various input and output devices.

  19. Progress in lattice Boltzmann methods for magnetohydrodynamic flows relevant to fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Pattison, M.J. [MetaHeuristics LLC, 3944 State St., Ste. 350, Santa Barbara, CA 93105 (United States)], E-mail: martin@metah.com; Premnath, K.N. [MetaHeuristics LLC, 3944 State St., Ste. 350, Santa Barbara, CA 93105 (United States); UCSB, Chemical Engineering Department, Santa Barbara, CA 93106 (United States); Morley, N.B.; Abdou, M.A. [UCLA, MAE Department, 44-114 Engineering IV, 420 Westwood Pza, Los Angeles, CA 90095-1597 (United States)

    2008-05-15

    In this paper, an approach to simulating magnetohydrodynamic (MHD) flows based on the lattice Boltzmann method (LBM) is presented. The dynamics of the flow are simulated using a so-called multiple relaxation time (MRT) lattice Boltzmann equation (LBE), in which a source term is included for the Lorentz force. The evolution of the magnetic induction is represented by introducing a vector distribution function and then solving an appropriate lattice kinetic equation for this function. The solution of both distribution functions are obtained through a simple, explicit, and computationally efficient stream-and-collide procedure. The use of the MRT collision term enhances the numerical stability over that of a single relaxation time approach. To apply the methodology to solving practical problems, a new extrapolation-based method for imposing magnetic boundary conditions is introduced and a technique for simulating steady-state flows with low magnetic Prandtl number is developed. In order to resolve thin layers near the walls arising in the presence of high magnetic fields, a non-uniform gridding strategy is introduced through an interpolated-streaming step applied to both distribution functions. These advances are particularly important for applications in fusion engineering where liquid metal flows with low magnetic Prandtl numbers and high Hartmann numbers are introduced. A number of MHD benchmark problems, under various physical and geometrical conditions are presented, including 3-D MHD lid driven cavity flow, high Hartmann number flows and turbulent MHD flows, with good agreement with prior data. Due to the local nature of the method, the LBM also demonstrated excellent performance on parallel machines, with almost linear scaling up to 128 processors for a MHD flow problem.

  20. Fabrication and transfer assembly of microscale, solid-state light emitting diodes and solar cells for transparent and flexible electronics applications

    Science.gov (United States)

    Brueckner, Eric P.

    Efficiency metrics for some solid-state electronic materials systems have progressed to the point where theoretical limits are being approached. Gallium nitride-based lightemitting diodes and silicon solar cells, for example, have achieved such extraordinarily high performance metrics that only incremental improvements upon them are expected in the next decade of intense research. This pseudo-plateau in performance development means concentrated effort can now be placed on strategic implementation of these materials into platforms that fill a growing demand for high-performance consumer products. Such products have traditionally relied upon large-scale materials, but possibilities now exist for manipulating micro-scale, wafer-based devices in ways that promote improvements in areas of electrical current spreading, light absorption and extraction, and thermal management. To this end, my research has focused on routes to fabricating and assembling solid-state light-emitting diodes and solar cells of indium gallium nitride and single-crystalline silicon, respectively, in configurations which optimize characteristics of their performance. Specifically, I have worked, in collaboration with others, to achieve a processing strategy that creates dense arrays of indium gallium nitride light-emitting diodes on a silicon wafer of (111) orientation and assemble them onto transparent and flexible substrates. This work produced novel form factors for solid-state lighting where small, light-emitting devices were spatially distributed and integrated with color-converting phosphors in ways that controllably tuned their chromaticity. We also demonstrated that incredible passive heat dissipation with these micro-scale elements stemming naturally from their small size and integration with metal films serving dually as an electrically interconnecting medium. The cell design and etching strategies used were then transferred to a single-crystalline silicon system where small, ribbon

  1. Active Stabilization of a Diode Laser Injection Lock

    CERN Document Server

    Saxberg, Brendan; Gupta, Subhadeep

    2016-01-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  2. Active graphene-silicon hybrid diode for terahertz waves.

    Science.gov (United States)

    Li, Quan; Tian, Zhen; Zhang, Xueqian; Singh, Ranjan; Du, Liangliang; Gu, Jianqiang; Han, Jiaguang; Zhang, Weili

    2015-05-11

    Controlling the propagation properties of the terahertz waves in graphene holds great promise in enabling novel technologies for the convergence of electronics and photonics. A diode is a fundamental electronic device that allows the passage of current in just one direction based on the polarity of the applied voltage. With simultaneous optical and electrical excitations, we experimentally demonstrate an active diode for the terahertz waves consisting of a graphene-silicon hybrid film. The diode transmits terahertz waves when biased with a positive voltage while attenuates the wave under a low negative voltage, which can be seen as an analogue of an electronic semiconductor diode. Here, we obtain a large transmission modulation of 83% in the graphene-silicon hybrid film, which exhibits tremendous potential for applications in designing broadband terahertz modulators and switchable terahertz plasmonic and metamaterial devices.

  3. Active stabilization of a diode laser injection lock

    Science.gov (United States)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-06-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  4. The Adjunctive Soft-Tissue Diode Laser in Orthodontics.

    Science.gov (United States)

    Borzabadi-Farahani, Ali

    2017-04-01

    Lasers are a relatively new addition to the orthodontist's armamentarium. This article reviews the fundamental basic science of available soft-tissue lasers, with an emphasis on diode lasers, and discusses various adjunct applications of the diode laser for soft-tissue orthodontic procedures. Diode lasers function by cutting with an initiated hot tip and produce minimal to no interaction with healthy dental hard tissue, making them suitable for soft-tissue procedures. The contact cutting mode provides enhanced bloodless site visibility and facility to perform delicate soft tissue procedures, which is important in areas with difficult access. Such adjunctive uses include laser gingivectomy to improve oral hygiene or bracket positioning, esthetic laser gingival recontouring, and laser exposure of superficially impacted teeth. Selected cases treated with a 940-nm indium-gallium-arsenide-phosphide (InGaAsP) diode laser will be presented.

  5. Active graphene–silicon hybrid diode for terahertz waves

    Science.gov (United States)

    Li, Quan; Tian, Zhen; Zhang, Xueqian; Singh, Ranjan; Du, Liangliang; Gu, Jianqiang; Han, Jiaguang; Zhang, Weili

    2015-01-01

    Controlling the propagation properties of the terahertz waves in graphene holds great promise in enabling novel technologies for the convergence of electronics and photonics. A diode is a fundamental electronic device that allows the passage of current in just one direction based on the polarity of the applied voltage. With simultaneous optical and electrical excitations, we experimentally demonstrate an active diode for the terahertz waves consisting of a graphene–silicon hybrid film. The diode transmits terahertz waves when biased with a positive voltage while attenuates the wave under a low negative voltage, which can be seen as an analogue of an electronic semiconductor diode. Here, we obtain a large transmission modulation of 83% in the graphene–silicon hybrid film, which exhibits tremendous potential for applications in designing broadband terahertz modulators and switchable terahertz plasmonic and metamaterial devices. PMID:25959596

  6. Qualification of diode foil materials for excimer lasers

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R.G.; Shurter, R.P.; Rose, E.A.

    1989-01-01

    The Aurora facility at Los Alamos National Laboratory uses KrF excimer lasers to produce 248 nm light for inertial confinement fusion applications. Diodes in each amplifier produce relativistic electron beams to pump a Kr-F-Ar gas mixture. A foil is necessary to separate the vacuum diode from the laser gas. High tensile strength, high electron transmission, low ultraviolet reflectivity, and chemical compatibility with fluorine have been identified as requisite foil properties. Several different materials were acquired and tested for use as diode foils. Transmission and fluorine compatibility tests were performed using the Electron Gun Test Facility (EGTF) at Los Alamos. Off-line tests of tensile strength and reflectivity were performed. Titanium foil, which is commonly used as a diode foil, was found to generate solid and gaseous fluoride compounds, some of which are highly reactive in contact with water vapor. 6 refs., 6 figs., 1 tab.

  7. Qualification of diode foil materials for excimer lasers

    Science.gov (United States)

    Anderson, R. G.; Shurter, R. P.; Rose, E. A.

    The Aurora facility at Los Alamos National Laboratory uses KrF excimer lasers to produce 248 nm light for inertial confinement fusion applications. Diodes in each amplifier produce relativistic electron beams to pump a Kr-F-Ar gas mixture. A foil is necessary to separate the vacuum diode from the laser gas. High tensile strength, high electron transmission, low ultraviolet reflectivity, and chemical compatibility with fluorine have been identified as requisite foil properties. Several different materials were acquired and tested for use as diode foils. Transmission and fluorine compatibility tests were performed using the Electron Gun Test Facility (EGTF) at Los Alamos. Off-line tests of tensile strength and reflectivity were performed. Titanium foil, which is commonly used as a diode foil, was found to generate solid and gaseous fluoride compounds, some of which are highly reactive in contact with water vapor.

  8. Active graphene-silicon hybrid diode for terahertz waves

    Science.gov (United States)

    Li, Quan; Tian, Zhen; Zhang, Xueqian; Singh, Ranjan; Du, Liangliang; Gu, Jianqiang; Han, Jiaguang; Zhang, Weili

    2015-05-01

    Controlling the propagation properties of the terahertz waves in graphene holds great promise in enabling novel technologies for the convergence of electronics and photonics. A diode is a fundamental electronic device that allows the passage of current in just one direction based on the polarity of the applied voltage. With simultaneous optical and electrical excitations, we experimentally demonstrate an active diode for the terahertz waves consisting of a graphene-silicon hybrid film. The diode transmits terahertz waves when biased with a positive voltage while attenuates the wave under a low negative voltage, which can be seen as an analogue of an electronic semiconductor diode. Here, we obtain a large transmission modulation of 83% in the graphene-silicon hybrid film, which exhibits tremendous potential for applications in designing broadband terahertz modulators and switchable terahertz plasmonic and metamaterial devices.

  9. Application of Lossless Data Compression Techniques to Radio Astronomy Data flows

    CERN Document Server

    Natusch, Tim

    2014-01-01

    The modern practice of Radio Astronomy is characterized by extremes of data volume and rates, principally because of the direct relationship between the signal to noise ratio that can be achieved and the need to Nyquist sample the RF bandwidth necessary by way of support. The transport of these data flows is costly. By examining the statistical nature of typical data flows and applying well known techniques from the field of Information Theory the following work shows that lossless compression of typical radio astronomy data flows is in theory possible. The key parameter in determining the degree of compression possible is the standard deviation of the data. The practical application of compression could prove beneficial in reducing the costs of data transport and (arguably) storage for new generation instruments such as the Square Kilometer Array.

  10. A NONHYDROSTATIC NUMERICAL MODEL FOR DENSITY STRATIFIED FLOW AND ITS APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A modular numerical model was developed for simulating density-stratified flow in domains with irregular bottom topography. The model was designed for examining interactions between stratified flow and topography, e.g., tidally driven flow over two-dimensional sills or internal solitary waves propagating over a shoaling bed. The model was based on the non-hydrostatic vorticity-stream function equations for a continuously stratified fluid in a rotating frame. A self-adaptive grid was adopted in the vertical coordinate, the Alternative Direction Implicit (ADI) scheme was used for the time marching equations while the Poisson equation for stream-function was solved based on the Successive Over Relaxation (SOR) iteration with the Chebyshev acceleration. The numerical techniques were described and three applications of the model were presented.

  11. Electrification of particulate entrained fluid flows-Mechanisms, applications, and numerical methodology

    Science.gov (United States)

    Wei, Wei; Gu, Zhaolin

    2015-10-01

    Particulates in natural and industrial flows have two basic forms: liquid (droplet) and solid (particle). Droplets would be charged in the presence of the applied electric field (e.g. electrospray). Similar to the droplet charging, particles can also be charged under the external electric field (e.g. electrostatic precipitator), while in the absence of external electric field, tribo-electrostatic charging is almost unavoidable in gas-solid two-phase flows due to the consecutive particle contacts (e.g. electrostatic in fluidized bed or wind-blown sand). The particle charging may be beneficial, or detrimental. Although electrostatics in particulate entrained fluid flow systems have been so widely used and concerned, the mechanisms of particulate charging are still lack of a thorough understanding. The motivation of this review is to explore a clear understanding of particulate charging and movement of charged particulate in two-phase flows, by summarizing the electrification mechanisms, physical models of particulate charging, and methods of charging/charged particulate entrained fluid flow simulations. Two effective methods can make droplets charged in industrial applications: corona charging and induction charging. The droplet charge to mass ratio by corona charging is more than induction discharge. The particle charging through collisions could be attributed to electron transfer, ion transfer, material transfer, and/or aqueous ion shift on particle surfaces. The charges on charged particulate surface can be measured, nevertheless, the charging process in nature or industry is difficult to monitor. The simulation method might build a bridge of investigating from the charging process to finally charged state on particulate surface in particulate entrained fluid flows. The methodology combining the interface tracking under the action of the applied electric with the fluid flow governing equations is applicable to the study of electrohydrodynamics problems. The charge

  12. High performance parallel computing of flows in complex geometries: II. Applications

    Energy Technology Data Exchange (ETDEWEB)

    Gourdain, N; Gicquel, L; Staffelbach, G; Vermorel, O; Duchaine, F; Boussuge, J-F [Computational Fluid Dynamics Team, CERFACS, Toulouse, 31057 (France); Poinsot, T [Institut de Mecanique des Fluides de Toulouse, Toulouse, 31400 (France)], E-mail: Nicolas.gourdain@cerfacs.fr

    2009-01-01

    Present regulations in terms of pollutant emissions, noise and economical constraints, require new approaches and designs in the fields of energy supply and transportation. It is now well established that the next breakthrough will come from a better understanding of unsteady flow effects and by considering the entire system and not only isolated components. However, these aspects are still not well taken into account by the numerical approaches or understood whatever the design stage considered. The main challenge is essentially due to the computational requirements inferred by such complex systems if it is to be simulated by use of supercomputers. This paper shows how new challenges can be addressed by using parallel computing platforms for distinct elements of a more complex systems as encountered in aeronautical applications. Based on numerical simulations performed with modern aerodynamic and reactive flow solvers, this work underlines the interest of high-performance computing for solving flow in complex industrial configurations such as aircrafts, combustion chambers and turbomachines. Performance indicators related to parallel computing efficiency are presented, showing that establishing fair criterions is a difficult task for complex industrial applications. Examples of numerical simulations performed in industrial systems are also described with a particular interest for the computational time and the potential design improvements obtained with high-fidelity and multi-physics computing methods. These simulations use either unsteady Reynolds-averaged Navier-Stokes methods or large eddy simulation and deal with turbulent unsteady flows, such as coupled flow phenomena (thermo-acoustic instabilities, buffet, etc). Some examples of the difficulties with grid generation and data analysis are also presented when dealing with these complex industrial applications.

  13. Absolute technique for measuring internal electric fields in InGaN/GaN light-emitting diodes by electroreflectance applicable to all crystal orientations

    Science.gov (United States)

    Tanikawa, Tomoyuki; Shojiki, Kanako; Katayama, Ryuji; Kuboya, Shigeyuki; Matsuoka, Takashi; Honda, Yoshio; Amano, Hiroshi

    2017-08-01

    The internal electric fields in III-polar (0001), N-polar (000\\bar{1}), and semipolar (10\\bar{1}1) InGaN/GaN light-emitting diodes were investigated by electroreflectance (ER) spectroscopy. The ER spectra reflected the difference in the direction and strength of internal electric fields. Phase analyses of the ER signal revealed that only III-polar InGaN wells have the opposite direction of the internal electric field at zero bias voltage; this finding is in good agreement with the results of numerical analyses. Quantitative analyses of internal electric fields were conducted by the linewidth analyses of ER spectra. Our experimental results indicate that the absolute value of internal electric fields can be measured from ER spectra.

  14. Pressure effects in AlAs/InxGa1-xAs/GaAs resonant tunnelling diodes for application in micromachined sensors

    Institute of Scientific and Technical Information of China (English)

    Wang Jian; Zhang Wen-Dong; Xue Chen-Yang; Xiong Ji-Jun; Liu Jun; Xie Bin

    2007-01-01

    This paper reports the current-voltage characteristics of [001]-oriented AlAs/InxGal-xAs/GaAs resonant tunnelling diodes (RTDs) as a function of uniaxial external stress applied parallel to the [110] and the [110] orientations,and the output characteristics of the GaAs pressure sensor based on the pressure effect on the RTDs. Under [110]stress, the resonance peak voltages of the RTDs shift to more positive voltages. For [110] stress, the peaks shift toward more negative voltages. The resonance peak voltage is linearly dependent on the [110] and [110] stresses and the linear sensitivities are up to 0.69 mV/MPa,-0.69 mV/MPa respectively. For the pressure sensor, the linear sensitivity is up to 0.37 mV/kPa.

  15. Design, fabrication and characterization of In 0.23Ga 0.77As-channel planar Gunn diodes for millimeter wave applications

    Science.gov (United States)

    Li, Chong; Khalid, Ata; Paluchowski Caldwell, Sonia H.; Holland, Martin C.; Dunn, Geoff M.; Thayne, Iain G.; Cumming, David R. S.

    2011-10-01

    We present detailed design, fabrication and characterization of In 0.23Ga 0.77As-based planar Gunn diodes in this paper. The devices have AlGaAs/InGaAs/AlGaAs heterojunctions that were grown on a semi-insulating GaAs wafer using molecular beam epitaxy technology. Electron beam lithography was used to define anode and cathode terminal patterns. Devices with various anode-cathode separations (e.g. 4-1.4 μm) were fabricated on the same chip. Spectrum measurements showed oscillation frequencies between 36 GHz and 118 GHz in the fundamental transit-time mode of operation. These devices show great potential as millimeter wave and sub-millimeter wave signal sources for their small size, MMIC compatibility and lithographically controlled oscillation frequencies.

  16. Adaptive finite element simulation of flow and transport applications on parallel computers

    Science.gov (United States)

    Kirk, Benjamin Shelton

    The subject of this work is the adaptive finite element simulation of problems arising in flow and transport applications on parallel computers. Of particular interest are new contributions to adaptive mesh refinement (AMR) in this parallel high-performance context, including novel work on data structures, treatment of constraints in a parallel setting, generality and extensibility via object-oriented programming, and the design/implementation of a flexible software framework. This technology and software capability then enables more robust, reliable treatment of multiscale--multiphysics problems and specific studies of fine scale interaction such as those in biological chemotaxis (Chapter 4) and high-speed shock physics for compressible flows (Chapter 5). The work begins by presenting an overview of key concepts and data structures employed in AMR simulations. Of particular interest is how these concepts are applied in the physics-independent software framework which is developed here and is the basis for all the numerical simulations performed in this work. This open-source software framework has been adopted by a number of researchers in the U.S. and abroad for use in a wide range of applications. The dynamic nature of adaptive simulations pose particular issues for efficient implementation on distributed-memory parallel architectures. Communication cost, computational load balance, and memory requirements must all be considered when developing adaptive software for this class of machines. Specific extensions to the adaptive data structures to enable implementation on parallel computers is therefore considered in detail. The libMesh framework for performing adaptive finite element simulations on parallel computers is developed to provide a concrete implementation of the above ideas. This physics-independent framework is applied to two distinct flow and transport applications classes in the subsequent application studies to illustrate the flexibility of the

  17. Principles and applications of flow cytometry and cell sorting in companion animal medicine.

    Science.gov (United States)

    Wilkerson, Melinda J

    2012-01-01

    Flow cytometry measures multiple characteristic of single cells using light scatter properties and fluorescence properties of fluorescent probes with specificity to cellular constituents. The use of flow cytometry in the veterinary clinical laboratory has become more routine in veterinary diagnostic laboratories and institutions (http://www.vet.k-state.edu/depts/dmp/service/immunology/index.htm), and reference laboratories. The most common applications in small animal medicine includes quantitation of erythrocytes and leukocytes in automated hematology instruments, detection of antibodies to erythrocytes and platelets in cases of immune-mediated diseases, immunophenotyping of leukocytes and lymphocytes in immunodeficiency syndromes, or leukemias and lymphomas. DNA content analysis to identify aneuploidy or replicating cells in tumor preparations has not gained routine acceptance because of the variability of prognostic results. Other applications including cell sorting and multiplexing using microspheres are potential assays of the future once they become validated and the instrumentation footprint becomes more and more compact, less expensive, and easier to use.

  18. THE APPLICATION OF LASERS IN MEASUREMENT OF FLUID FLOW THROUGH DRILLING BIT NOZZLES

    Directory of Open Access Journals (Sweden)

    Radenko Drakulić

    1993-12-01

    Full Text Available Two optical methods based on laser and video technology and digital signal and image processing techniques - Laser Doppler velocimetry (LDV and Particle image velocimetry (PIV were applied in highly accurate fluid flow measurement. Their application in jet velocity measurement of flows through drilling bit nozzles is presented. The role of nozzles in drilling technology together with procedures and tests performed on their optimization are reviewed. In addition, some experimental results for circular nozzle obtained both with LDV and PIV are elaborated. The experimental set-up and the testing procedure arc briefly discussed, as well as potential improvements in the design. Possible other applications of LDV and PIV in the domain of petroleum engineering are suggested (the paper is published in Croatian.

  19. The novel transparent sputtered p-type CuO thin films and Ag/p-CuO/n-Si Schottky diode applications

    Directory of Open Access Journals (Sweden)

    A. Tombak

    2015-01-01

    Full Text Available In the current paper, the physical properties and microelectronic parameters of direct current (DC sputtered p-type CuO film and diode have been investigated. The film of CuO as oxide and p-type semiconductor is grown onto glass and n-Si substrates by reactive DC sputtering at 250 °C. After deposition, a post-annealing procedure is applied at various temperatures in ambient. Through this research, several parameters are determined such structural, optical and electrical magnitudes. The thickness of CuO thin films goes from 122 to 254 nm. A (111-oriented cubic crystal structure is revealed by X-ray analysis. The grain size is roughly depending on the post-annealing temperature, it increases with temperature within the 144–285 nm range. The transmittance reaches 80% simultaneously in visible and infrared bands. The optical band gap is varied between 1.99 and 2.52 eV as a result of annealing temperature while the resistivity and the charge carrier mobility decrease with an increase in temperature from 135 to 14 Ω cm and 0.92 to 0.06 cm2/Vs, respectively. The surface of samples is homogenous, bright dots are visible when temperature reaches the highest value. As a diode, Ag/CuO/n-Si exhibits a non-ideal behavior and the ideality factor is about 3.5. By Norde method, the barrier height and the series resistance are extracted and found to be 0.96 V and 86.6 Ω respectively.

  20. Particle motion in unsteady two-dimensional peristaltic flow with application to the ureter

    Science.gov (United States)

    Jiménez-Lozano, Joel; Sen, Mihir; Dunn, Patrick F.

    2009-04-01

    Particle motion in an unsteady peristaltic fluid flow is analyzed. The fluid is incompressible and Newtonian in a two-dimensional planar geometry. A perturbation method based on a small ratio of wave height to wavelength is used to obtain a closed-form solution for the fluid velocity field. This analytical solution is used in conjunction with an equation of motion for a small rigid sphere in nonuniform flow taking Stokes drag, virtual mass, Faxén, Basset, and gravity forces into account. Fluid streamlines and velocity profiles are calculated. Theoretical values for pumping rates are compared with available experimental data. An application to ureteral peristaltic flow is considered since fluid flow in the ureter is sometimes accompanied by particles such as stones or bacteriuria. Particle trajectories for parameters that correspond to calcium oxalates for calculosis and Escherichia coli type for bacteria are analyzed. The findings show that retrograde or reflux motion of the particles is possible and bacterial transport can occur in the upper urinary tract when there is a partial occlusion of the wave. Dilute particle mixing is also investigated, and it is found that some of the particles participate in the formation of a recirculating bolus, and some of them are delayed in transit and eventually reach the walls. This can explain the failure of clearing residuals from the upper urinary tract calculi after successful extracorporeal shock wave lithotripsy. The results may also be relevant to the transport of other physiological fluids and industrial applications in which peristaltic pumping is used.

  1. Air flow assisted ionization for remote sampling of ambient mass spectrometry and its application.

    Science.gov (United States)

    He, Jiuming; Tang, Fei; Luo, Zhigang; Chen, Yi; Xu, Jing; Zhang, Ruiping; Wang, Xiaohao; Abliz, Zeper

    2011-04-15

    Ambient ionization methods are an important research area in mass spectrometry (MS) analysis. Under ambient conditions, the gas flow and atmospheric pressure significantly affect the transfer and focusing of ions. The design and implementation of air flow assisted ionization (AFAI) as a novel and effective, remote sampling method for ambient mass spectrometry are described herein. AFAI benefits from a high extracting air flow rate. A systematic investigation of the extracting air flow in the AFAI system has been carried out, and it has been demonstrated not only that it plays a role in the effective capture and remote transport of charged droplets, but also that it promotes desolvation and ion formation, and even prevents ion fragmentation during the ionization process. Moreover, the sensitivity of remote sampling ambient MS analysis was improved significantly by the AFAI method. Highly polar and nonpolar molecules, including dyes, pharmaceutical samples, explosives, drugs of abuse, protein and volatile compounds, have been successfully analyzed using AFAI-MS. The successful application of the technique to residue detection on fingers, large object analysis and remote monitoring in real time indicates its potential for the analysis of a variety of samples, especially large objects. The ability to couple this technique with most commercially available MS instruments with an API interface further enhances its broad applicability.

  2. Applications Determine the Best Model to Predict Flow Duration Curves in Ungauged Basins

    Science.gov (United States)

    Muller, M. F.; Thompson, S. E.

    2014-12-01

    Flow duration curves (FDCs) are an important tool for watershed management and their prediction in ungauged catchments is a challenging problem. Selecting the most appropriate model for prediction the FDC is itself a challenge that determines how theoretical improvements in prediction are transferred into engineering practice. Available performance metrics (e.g., Nash Sutcliffe Coefficient, error on flow moments) typically consider the aggregated ability of the model to predict all streamflow quantiles. These metrics may be inappropriate for model selection in practice because watershed management decisions are typically driven by a limited number of streamflow quantiles that may be poorly represented by an aggregate performance metric. As an illustrative case study, the performance of three distinct FDC prediction approaches -- graphical, statistical and process-based -- are compared for ungauged streams in Nepal. The practical application of these predictions is to inform the design of run-of-river hydropower plants. The process-based approach provides the best prediction of the observed flow distribution and results in significantly higher Nash coefficients. However, the graphical approach provides the best prediction of the flow quantiles that are most relevant for hydropower design and reduces the design error caused by streamflow estimation. To assist in an application driven model selection process, we propose a novel model selection framework.

  3. A Method of Three-Dimensional Micro-Rotational Flow Generation for Biological Applications

    Directory of Open Access Journals (Sweden)

    Yaxiaer Yalikun

    2016-08-01

    Full Text Available We report a convenient method to create a three-dimensional micro-rotational fluidic platform for biological applications in the direction of a vertical plane (out-of-plane without contact in an open space. Unlike our previous complex fluidic manipulation system, this method uses a micro-rotational flow generated near a single orifice when the solution is pushed from the orifice by using a single pump. The three-dimensional fluidic platform shows good potential for fluidic biological applications such as culturing, stimulating, sorting, and manipulating cells. The pattern and velocity of the micro-rotational flow can be controlled by tuning the parameters such as the flow rate and the liquid-air interface height. We found that bio-objects captured by the micro-rotational flow showed self-rotational motion and orbital motion. Furthermore, the path length and position, velocity, and pattern of the orbital motion of the bio-object could be controlled. To demonstrate our method, we used embryoid body cells. As a result, the orbital motion had a maximum length of 2.4 mm, a maximum acceleration of 0.63 m/s2, a frequency of approximately 0.45 Hz, a maximum velocity of 15.4 mm/s, and a maximum rotation speed of 600 rpm. The capability to have bio-objects rotate or move orbitally in three dimensions without contact opens up new research opportunities in three-dimensional microfluidic technology.

  4. Diode-pumped laser with improved pumping system

    Science.gov (United States)

    Chang, Jim J.

    2004-03-09

    A laser wherein pump radiation from laser diodes is delivered to a pump chamber and into the lasing medium by quasi-three-dimensional compound parabolic concentrator light channels. The light channels have reflective side walls with a curved surface and reflective end walls with a curved surface. A flow tube between the lasing medium and the light channel has a roughened surface.

  5. Optimal bounds with semidefinite programming: An application to stress-driven shear flows.

    Science.gov (United States)

    Fantuzzi, G; Wynn, A

    2016-04-01

    We introduce an innovative numerical technique based on convex optimization to solve a range of infinite-dimensional variational problems arising from the application of the background method to fluid flows. In contrast to most existing schemes, we do not consider the Euler-Lagrange equations for the minimizer. Instead, we use series expansions to formulate a finite-dimensional semidefinite program (SDP) whose solution converges to that of the original variational problem. Our formulation accounts for the influence of all modes in the expansion, and the feasible set of the SDP corresponds to a subset of the feasible set of the original problem. Moreover, SDPs can be easily formulated when the fluid is subject to imposed boundary fluxes, which pose a challenge for the traditional methods. We apply this technique to compute rigorous and near-optimal upper bounds on the dissipation coefficient for flows driven by a surface stress. We improve previous analytical bounds by more than 10 times and show that the bounds become independent of the domain aspect ratio in the limit of vanishing viscosity. We also confirm that the dissipation properties of stress-driven flows are similar to those of flows subject to a body force localized in a narrow layer near the surface. Finally, we show that SDP relaxations are an efficient method to investigate the energy stability of laminar flows driven by a surface stress.

  6. Uncertainty Quantification for atmospheric flows: natural terrain and urban area applications

    Science.gov (United States)

    García-Sánchez, Clara; Gorlé, Catherine

    2016-11-01

    Modeling Atmospheric Boundary Layer (ABL) flows is an important concern for a wide range of applications, including the assessment of air quality and wind energy resources. The complexity of these ABL flows, whether in urban areas or over natural terrain, still poses a challenge for Reynolds-averaged Navier-Stokes models. In the present research, the effect of uncertainties in the inflow boundary conditions on the prediction of the flow patterns is investigated, considering two test cases for which field measurements are available: the Askervein Hill experiment (natural terrain) and the Joint Urban 2003 campaign (urban environment). The uncertainty in the inflow boundary conditions is represented by three uncertain parameters, and a non-intrusive polynomial chaos method is used to propagate these uncertainties to the quantities of interest, namely the prediction of the velocity at the locations of the different measurement stations. The results highlight some differences between ABL flows over natural terrain and those in an urban environment, in particular regarding the influence of the different uncertain parameters on the prediction of the velocity field. The implications for evaluating the effect of inflow uncertainties in these different types of ABL flows will be discussed.

  7. Applications of weakly compressible model to turbulent flow problem towards adaptive turbulence simulation

    Science.gov (United States)

    Tsuji, Takuya; Yokomine, Takehiko; Shimizu, Akihiko

    2002-11-01

    We have been engaged in the development of multi-scale adaptive simulation technique for incompressible turbulent flow. This is designed as that important scale components in the flow field are detected automatically by lifting wavelet and solved selectively. In conventional incompressible scheme, it is very common to solve Poisson equation of pressure to meet the divergence free constraints of incompressible flow. It may be not impossible to solve the Poisson eq. in the adaptive way, but this is very troublesome because it requires generation of control volume at each time step. We gave an eye on weakly compressible model proposed by Bao(2001). This model was derived from zero Mach limit asymptotic analysis of compressible Navier-Stokes eq. and does not need to solve the Poisson eq. at all. But it is relatively new and it requires demonstration study before the combination with the adaptation by wavelet. In present study, 2-D and 3-D Backstep flow were selected as test problems and applicability to turbulent flow is verified in detail. Besides, combination of adaptation by wavelet with weakly compressible model towards the adaptive turbulence simulation is discussed.

  8. Clinical applications of high-speed blood flow measurements with diffuse correlation spectroscopy

    Science.gov (United States)

    Parthasarathy, Ashwin B.; Baker, Wesley B.; Gannon, Kimberly; Mullen, Michael T.; Detre, John A.; Yodh, Arjun G.

    2017-02-01

    Diffuse Correlation Spectroscopy (DCS) is an increasingly popular non-invasive optical technique to clinically measure deep tissue blood flow, albeit at slow measurement rates of 0.5-1 Hz. We recently reported the development of a new `fast' DCS instrument that continuously measures blood flow at 50-100 Hz (simultaneously from 8 channels), using conventional DCS sources/detectors, and optimized software computations. A particularly interesting result was our ability to optically record pulsatile micro-vascular blood flow waveforms, and therein readily identify high frequency features such as the dicrotic notch. Here, we showcase the utility and potential of high-speed measurements of blood flow (and arterial blood pressure) in a few clinical applications. First, we employ the fast-DCS instrumentation to measure cerebral autoregulation (CVAR) dynamics. Cerebral autoregulation refers to the mechanism by which cerebral blood flow (CBF) is maintained during fluctuations in blood pressure; CVAR is impaired in the injured brain. We derive an index of autoregulation by measuring the rates of decrease (and recovery) of blood flow and blood pressure following a sudden, induced change in systemic blood pressure (e.g., bilateral thigh cuff deflation). Our pilot experiments in healthy volunteers show that DCS measured rates of micro-vascular regulation are comparable to conventional large vessel regulatory metrics (e.g., measured with transcranial Doppler ultrasound). Second, we utilized pulsatile blood flow oscillations in cerebral arteries to estimate the critical closing pressure (CrCP), i.e., the arterial blood pressure at which CBF approaches zero. Pilot experiments in healthy subjects show good agreement between CrCP measured with DCS and transcranial Doppler ultrasound.

  9. Improved flow measurement using microbubble contrast agents and disruption-replenishment: clinical application to tumour monitoring.

    Science.gov (United States)

    Hudson, John M; Williams, Ross; Lloyd, Brendan; Atri, Mostafa; Kim, Tae Kyoung; Bjarnason, Georg; Burns, Peter N

    2011-08-01

    Dynamic contrast-enhanced ultrasound (DCE-US) and the method of disruption replenishment has been used for the past 10 years to measure flow noninvasively in the microcirculation. However, the method's perceived poor reproducibility remains a major impediment to widespread clinical acceptance. Poor reproducibility can be attributed, in part, to the curve fitting model that is used to quantify microbubble enhancement. Flow measurement in tumours is further complicated by the spatial and temporal heterogeneity of tumour blood flow. In this work, we evaluate three models of microbubble disruption and replenishment (mono-exponential, a simplified multivessel model by Krix and the lognormal perfusion model) using clinical data (11 patients, 41 sessions) from an antiangiogenic drug trial for metastatic renal cell carcinoma (RCC) and evaluate their contribution to the measurement's variability. Compared with the mono-exponential model, the lognormal perfusion model decreased the variability of intra-session velocity and blood volume measurements by 33% and 34%, respectively. Blood volume assessment using the lognormal perfusion model was comparable to Krix's mutlivessel model. Flow velocity measurement was 18% less variable for the lognormal perfusion model compared with the multivessel model. To further decrease flow measurement variability, we examine a method that exploits microbubble flow dynamics to discard the contribution of flow in large arteries and isolate the portion of the tumour microvasculature that is most sensitive to vessel targeting therapies. The method is validated with an in vitro phantom study prior to its application to the RCC clinical data set. Combined with the lognormal perfusion model, this method decreased the inter-plane variability of clinical measurements of relative tumour blood volume, in some cases by up to 20%.

  10. 1/f noise in forward biased high voltage 4H-SiC Schottky diodes

    Science.gov (United States)

    Shabunina, Eugenia I.; Levinshtein, Michael E.; Shmidt, Natalia M.; Ivanov, Pavel A.; Palmour, John W.

    2014-06-01

    The 1/f noise has been investigated for the first time at 300 and 77 K in high-quality 4H-SiC Schottky diodes. It is shown that, at 77 K, the dependence of the spectral noise density on current, SI(I), differs fundamentally between the cases of the current flowing through the main part of the diode with a comparatively high barrier and the current flowing through the nano-sized patches with a comparatively low barrier.

  11. Development and validation of chemistry agnostic flow battery cost performance model and application to nonaqueous electrolyte systems: Chemistry agnostic flow battery cost performance model

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Alasdair [Pacific Northwest National Laboratory (PNNL), 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Thomsen, Edwin [Pacific Northwest National Laboratory (PNNL), 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Reed, David [Pacific Northwest National Laboratory (PNNL), 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Stephenson, David [Pacific Northwest National Laboratory (PNNL), 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Sprenkle, Vincent [Pacific Northwest National Laboratory (PNNL), 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Liu, Jun [Pacific Northwest National Laboratory (PNNL), 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Viswanathan, Vilayanur [Pacific Northwest National Laboratory (PNNL), 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA

    2016-01-01

    A chemistry agnostic cost performance model is described for a nonaqueous flow battery. The model predicts flow battery performance by estimating the active reaction zone thickness at each electrode as a function of current density, state of charge, and flow rate using measured data for electrode kinetics, electrolyte conductivity, and electrode-specific surface area. Validation of the model is conducted using a 4kW stack data at various current densities and flow rates. This model is used to estimate the performance of a nonaqueous flow battery with electrode and electrolyte properties used from the literature. The optimized cost for this system is estimated for various power and energy levels using component costs provided by vendors. The model allows optimization of design parameters such as electrode thickness, area, flow path design, and operating parameters such as power density, flow rate, and operating SOC range for various application duty cycles. A parametric analysis is done to identify components and electrode/electrolyte properties with the highest impact on system cost for various application durations. A pathway to 100$kWh-1 for the storage system is identified.

  12. Nanoscale coatings for erosion and corrosion protection of copper microchannel coolers for high powered laser diodes

    Science.gov (United States)

    Flannery, Matthew; Fan, Angie; Desai, Tapan G.

    2014-03-01

    High powered laser diodes are used in a wide variety of applications ranging from telecommunications to industrial applications. Copper microchannel coolers (MCCs) utilizing high velocity, de-ionized water coolant are used to maintain diode temperatures in the recommended range to produce stable optical power output and control output wavelength. However, aggressive erosion and corrosion attack from the coolant limits the lifetime of the cooler to only 6 months of operation. Currently, gold plating is the industry standard for corrosion and erosion protection in MCCs. However, this technique cannot perform a pin-hole free coating and furthermore cannot uniformly cover the complex geometries of current MCCs involving small diameter primary and secondary channels. Advanced Cooling Technologies, Inc., presents a corrosion and erosion resistant coating (ANCERTM) applied by a vapor phase deposition process for enhanced protection of MCCs. To optimize the coating formation and thickness, coated copper samples were tested in 0.125% NaCl solution and high purity de-ionized (DIW) flow loop. The effects of DIW flow rates and qualities on erosion and corrosion of the ANCERTM coated samples were evaluated in long-term erosion and corrosion testing. The robustness of the coating was also evaluated in thermal cycles between 30°C - 75°C. After 1000 hours flow testing and 30 thermal cycles, the ANCERTM coated copper MCCs showed a corrosion rate 100 times lower than the gold plated ones and furthermore were barely affected by flow rates or temperatures thus demonstrating superior corrosion and erosion protection and long term reliability.

  13. Comparison of SHG Power Modulation by Wavelength Detuning of DFB- and DBR-Tapered Laser Diodes

    DEFF Research Database (Denmark)

    Christensen, Mathias; Hansen, Anders Kragh; Noordegraaf, Danny

    2016-01-01

    Pulsed visible lasers are used for a number of applications such as laser displays and medical treatments. Generating this visible light by direct frequency doubling of high power diode lasers opens new possibilities on how the power modulation can be performed. We present an investigation...... of the response of the second harmonic light to perturbations of the infrared laser diode and compare how the response differs for DFB- and DBR-Tapered laser diodes. We show that the visible light can be modulated from CW to kHz with modulation depths above 90% by wavelength detuning the laser diode....

  14. A Survey on Small Size Diodes For Microwave And Millimeter Wave Frequency Region

    Directory of Open Access Journals (Sweden)

    Rahul Ranjan, Prashant Kumar, Neha Singh

    2014-06-01

    Full Text Available This paper attempts to present a collection of microwave and millimetre wave semiconductor diodes. These semiconductor diodes are operates at microwave frequencies and millimetre frequencies. The invention of these semiconductor diodes led to almost complete replacement of vacuum devices which are bulky and large in size. Because of small size a large number of diodes can integrate on a single chip and this arrangement forms very large-scale integrated circuits which led to solid-state replacement on computer switching circuits. This paper surveys characteristics, applications, advantages and disadvantages of microwave and millimetre wave semiconductor devices.

  15. Application of Tank Model for Predicting Water Balance and Flow Discharge Components of Cisadane Upper Catchment

    Directory of Open Access Journals (Sweden)

    Nana Mulyana Arifjaya

    2012-01-01

    Full Text Available The concept of hydrological tank model was well described into four compartments (tanks. The first tank (tank A comprised of one vertical (qA0 and two lateral (qA1 and qA2 water flow components and tank B comprised of one vertical (qB0 and one lateral (qB1 water flow components. Tank C comprised of one vertical (qC0 and one lateral (qC1 water flow components, whereas tank D comprised of one lateral water flow component (qD1.  These vertical water flows would also contribute to the depletion of water flow in the related tanks but would replenish tanks in the deeper layers. It was assumed that at all lateral water flow components would finally accumulate in one stream, summing-up of the lateral water flow, much or less, should be equal to the water discharge (Qo at specified time concerns. Tank A received precipitation (R and evapo-transpiration (ET which was its gradientof (R-ET over time would become the driving force for the changes of water stored in the soil profiles and thosewater flows leaving the soil layer.  Thus tank model could describe th vertical and horizontal water flow withinthe watershed. The research site was Cisadane Upper Catchment, located at Pasir Buncir Village of CaringinSub-District within the Regency of Bogor in West Java Province.  The elevations ranged 512 –2,235 m above sealevel, with a total drainage area of 1,811.5 ha and total length of main stream of 14,340.7 m.  The land cover wasdominated by  forest  with a total of 1,044.6 ha (57.67%,  upland agriculture with a total of 477.96 ha (26.38%,mixed garden with a total of 92.85 ha(5.13% and semitechnical irigated rice field with a total of 196.09 ha (10,8%.  The soil was classified as hydraquent (96.6% and distropept (3.4%.  Based on the calibration of tank model application in the study area, the resulting coefficient of determination (R2 was 0.72 with model efficiency (NSEof= 0.75, thus tank model could well illustrate the water flow distribution of

  16. Application of partially-coupled hydro-mechanical schemes to multiphase flow problems

    Science.gov (United States)

    Tillner, Elena; Kempka, Thomas

    2016-04-01

    Utilization of subsurface reservoirs by fluid storage or production generally triggers pore pressure changes and volumetric strains in reservoirs and cap rocks. The assessment of hydro-mechanical effects can be undertaken using different process coupling strategies. The fully-coupled geomechanics and flow simulation, constituting a monolithic system of equations, is rarely applied for simulations involving multiphase fluid flow due to the high computational efforts required. Pseudo-coupled simulations are driven by static tabular data on porosity and permeability changes as function of pore pressure or mean stress, resulting in a rather limited flexibility when encountering complex subsurface utilization schedules and realistic geological settings. Partially-coupled hydro-mechanical simulations can be distinguished into one-way and iterative two-way coupled schemes, whereby the latter one is based on calculations of flow and geomechanics, taking into account the iterative exchange of coupling parameters between the two respective numerical simulators until convergence is achieved. In contrast, the one-way coupling scheme is determined by the provision of pore pressure changes calculated by the flow simulator to the geomechanical simulator neglecting any feedback. In the present study, partially-coupled two-way schemes are discussed in view of fully-coupled single-phase flow and geomechanics, and their applicability to multiphase flow simulations. For that purpose, we introduce a comparison study between the different coupling schemes, using selected benchmarks to identify the main requirements for the partially-coupled approach to converge with the numerical solution of the fully-coupled one.

  17. Validation and application of an high-order spectral difference method for flow induced noise simulation

    KAUST Repository

    Parsani, Matteo

    2011-09-01

    The main goal of this paper is to develop an efficient numerical algorithm to compute the radiated far field noise provided by an unsteady flow field from bodies in arbitrary motion. The method computes a turbulent flow field in the near fields using a high-order spectral difference method coupled with large-eddy simulation approach. The unsteady equations are solved by advancing in time using a second-order backward difference formulae scheme. The nonlinear algebraic system arising from the time discretization is solved with the nonlinear lowerupper symmetric GaussSeidel algorithm. In the second step, the method calculates the far field sound pressure based on the acoustic source information provided by the first step simulation. The method is based on the Ffowcs WilliamsHawkings approach, which provides noise contributions for monopole, dipole and quadrupole acoustic sources. This paper will focus on the validation and assessment of this hybrid approach using different test cases. The test cases used are: a laminar flow over a two-dimensional (2D) open cavity at Re = 1.5 × 10 3 and M = 0.15 and a laminar flow past a 2D square cylinder at Re = 200 and M = 0.5. In order to show the application of the numerical method in industrial cases and to assess its capability for sound field simulation, a three-dimensional turbulent flow in a muffler at Re = 4.665 × 10 4 and M = 0.05 has been chosen as a third test case. The flow results show good agreement with numerical and experimental reference solutions. Comparison of the computed noise results with those of reference solutions also shows that the numerical approach predicts noise accurately. © 2011 IMACS.

  18. Experimental studies of a microsecond plasma opening switch in the positive polarity regime with inductive load/extraction ion diode

    Science.gov (United States)

    Bystritskii, V. M.; Lisitsyn, I. V.; Sinebryukhov, V. A.; Volkov, S. N.; Krasik, Ya. E.

    1992-06-01

    Systematic studies of the microsecond plasma opening switch (MPOS) operation in the positive polarity of its inner electrode with an inductive load/B-applied ion diode of the extraction type at a level of 0.3 TW of dissipated power were performed at the DOUBLE generator (300 kA, 480 kV, 1 μs). The detailed measurements of ion flow parameters in the conductive phase of the MPOS showed the considerable enhancement of the ion current amplitude over the thermal flow limit (3-10 times) which is coupled with a significant decrease of electron conductivity in the MPOS across its self-magnetic field. The positive polarity MPOS operation proved to be more critical to the stored current amplitudes and geometry of the electrodes in comparison with the negative polarity case. This fact resulted in limitations of satisfactory performance of the MPOS involving short high-voltage pulse duration, low stored current amplitudes, and a narrow region of acceptable electrode diameters. The variation of the diode anode-cathode (AC) gap provided a sensitive control of the MPOS + magnetically insulated diode (MID) system, which displayed very strong coupling, resulting in clamping of the output voltage in a wide region of diode impedances. The early long-duration (<300 ns) high-voltage (50-200 kV) prepulse improves plasma production at the anode of the MID prior to the application of the main pulse. The optimal performance of the MPOS+MID system was realized at the level of ZMPOS/ZMID = 2.5. The energy of the extracted high-power ion beam made up 3.5 kJ, its power being 120 GW with 40% efficiency of energy transfer from MPOS to the MID.

  19. Wavelength stabilized multi-kW diode laser systems

    Science.gov (United States)

    Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

    2015-03-01

    We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

  20. In vivo dosimetry with silicon diodes in total body irradiation

    Science.gov (United States)

    Oliveira, F. F.; Amaral, L. L.; Costa, A. M.; Netto, T. G.

    2014-02-01

    The aim of this work is the characterization and application of silicon diode detectors for in vivo dosimetry in total body irradiation (TBI) treatments. It was evaluated the diode response with temperature, dose rate, gantry angulations and field size. A maximum response variation of 2.2% was obtained for temperature dependence. The response variation for dose rate and angular was within 1.2%. For field size dependence, the detector response increased with field until reach a saturation region, where no more primary radiation beam contributes for dose. The calibration was performed in a TBI setup. Different lateral thicknesses from one patient were simulated and then the calibration factors were determined by means of maximum depth dose readings. Subsequent to calibration, in vivo dosimetry measurements were performed. The response difference between diode readings and the prescribed dose for all treatments was below 4%. This difference is in agreement as recommended by the International Commission on Radiation Units and Measurements (ICRU), which is ±5%. The present work to test the applicability of a silicon diode dosimetry system for performing in vivo dose measurements in TBI techniques presented good results. These measurements demonstrated the value of diode dosimetry as a treatment verification method and its applicability as a part of a quality assurance program in TBI treatments.

  1. The international river interface cooperative: Public domain flow and morphodynamics software for education and applications

    Science.gov (United States)

    Nelson, Jonathan M.; Shimizu, Yasuyuki; Abe, Takaaki; Asahi, Kazutake; Gamou, Mineyuki; Inoue, Takuya; Iwasaki, Toshiki; Kakinuma, Takaharu; Kawamura, Satomi; Kimura, Ichiro; Kyuka, Tomoko; McDonald, Richard R.; Nabi, Mohamed; Nakatsugawa, Makoto; Simões, Francisco R.; Takebayashi, Hiroshi; Watanabe, Yasunori

    2016-07-01

    This paper describes a new, public-domain interface for modeling flow, sediment transport and morphodynamics in rivers and other geophysical flows. The interface is named after the International River Interface Cooperative (iRIC), the group that constructed the interface and many of the current solvers included in iRIC. The interface is entirely free to any user and currently houses thirteen models ranging from simple one-dimensional models through three-dimensional large-eddy simulation models. Solvers are only loosely coupled to the interface so it is straightforward to modify existing solvers or to introduce other solvers into the system. Six of the most widely-used solvers are described in detail including example calculations to serve as an aid for users choosing what approach might be most appropriate for their own applications. The example calculations range from practical computations of bed evolution in natural rivers to highly detailed predictions of the development of small-scale bedforms on an initially flat bed. The remaining solvers are also briefly described. Although the focus of most solvers is coupled flow and morphodynamics, several of the solvers are also specifically aimed at providing flood inundation predictions over large spatial domains. Potential users can download the application, solvers, manuals, and educational materials including detailed tutorials at www.-i-ric.org. The iRIC development group encourages scientists and engineers to use the tool and to consider adding their own methods to the iRIC suite of tools.

  2. An anisotropic numerical model for thermal hydraulic analyses: application to liquid metal flow in fuel assemblies

    Science.gov (United States)

    Vitillo, F.; Vitale Di Maio, D.; Galati, C.; Caruso, G.

    2015-11-01

    A CFD analysis has been carried out to study the thermal-hydraulic behavior of liquid metal coolant in a fuel assembly of triangular lattice. In order to obtain fast and accurate results, the isotropic two-equation RANS approach is often used in nuclear engineering applications. A different approach is provided by Non-Linear Eddy Viscosity Models (NLEVM), which try to take into account anisotropic effects by a nonlinear formulation of the Reynolds stress tensor. This approach is very promising, as it results in a very good numerical behavior and in a potentially better fluid flow description than classical isotropic models. An Anisotropic Shear Stress Transport (ASST) model, implemented into a commercial software, has been applied in previous studies, showing very trustful results for a large variety of flows and applications. In the paper, the ASST model has been used to perform an analysis of the fluid flow inside the fuel assembly of the ALFRED lead cooled fast reactor. Then, a comparison between the results of wall-resolved conjugated heat transfer computations and the results of a decoupled analysis using a suitable thermal wall-function previously implemented into the solver has been performed and presented.

  3. The international river interface cooperative: Public domain flow and morphodynamics software for education and applications

    Science.gov (United States)

    Nelson, Jonathan M.; Shimizu, Yasuyuki; Abe, Takaaki; Asahi, Kazutake; Gamou, Mineyuki; Inoue, Takuya; Iwasaki, Toshiki; Kakinuma, Takaharu; Kawamura, Satomi; Kimura, Ichiro; Kyuka, Tomoko; McDonald, Richard R.; Nabi, Mohamed; Nakatsugawa, Makoto; Simoes, Francisco J.; Takebayashi, Hiroshi; Watanabe, Yasunori

    2016-01-01

    This paper describes a new, public-domain interface for modeling flow, sediment transport and morphodynamics in rivers and other geophysical flows. The interface is named after the International River Interface Cooperative (iRIC), the group that constructed the interface and many of the current solvers included in iRIC. The interface is entirely free to any user and currently houses thirteen models ranging from simple one-dimensional models through three-dimensional large-eddy simulation models. Solvers are only loosely coupled to the interface so it is straightforward to modify existing solvers or to introduce other solvers into the system. Six of the most widely-used solvers are described in detail including example calculations to serve as an aid for users choosing what approach might be most appropriate for their own applications. The example calculations range from practical computations of bed evolution in natural rivers to highly detailed predictions of the development of small-scale bedforms on an initially flat bed. The remaining solvers are also briefly described. Although the focus of most solvers is coupled flow and morphodynamics, several of the solvers are also specifically aimed at providing flood inundation predictions over large spatial domains. Potential users can download the application, solvers, manuals, and educational materials including detailed tutorials at www.-i-ric.org. The iRIC development group encourages scientists and engineers to use the tool and to consider adding their own methods to the iRIC suite of tools.

  4. Towards High-Performance Network Application Identification With Aggregate-Flow Cache

    Directory of Open Access Journals (Sweden)

    Fei He

    2011-05-01

    Full Text Available Classifying network traffic according to their application-layer protocols is an important task in modern networks for traffic management and network security. Existing payload-based or statistical methods ofapplication identification cannot meet the demand of both high performance and accurate identificationat the same time. We propose an application identification framework that classifies traffic at aggregateflow level leveraging aggregate-flow cache. A detailed traffic classifier designed based on this framework is illustrated to improve the throughput of payload-based identification methods. We further optimize the classifier by proposing an efficient design of aggregate-flow cache. The cache design employs a frequency-based, recency-aware replacement algorithm based on the analysis of temporal locality of aggregate-flow cache. Experiments on real-world traces show that our traffic classifier with aggregateflow cache can reduce up to 95% workload of backend identification engine. The proposed cache replacement algorithm outperforms well-known replacement algorithms, and achieves 90% of the optimal performance using only 15% of memory. The throughput of a payload-based identification system, L7-filter [1], is increased by up to 5.1 times by using our traffic classifier design.

  5. Novel high peak current pulsed diode laser sources for direct material processing

    Science.gov (United States)

    Traub, M.; Bock, M.; Hoffmann, H.-D.; Bartram, M.

    2007-02-01

    Diode laser systems are well established for applications which demand high continuous wave (cw) power. These applications are material processing like cutting and welding of metals as well as polymers where diode laser systems are less expensive and more compact than solid state lasers. Even though the optical output power and the beam quality of diode lasers are increasing steadily, the use of these sources is generally limited to cw applications. For processes during which ablating of material is demanded, however, conventional diode lasers are inferior compared to pulsed solid state lasers as diode lasers suffer from the absence of optical intracavity q-switching. Some examples of these applications are coating removal and marking. To overcome this drawback, we have developed several diode laser systems that use high peak-current drivers and thereby allow to operate the diode lasers at currents up to 500 A. The pulse source was tested with fiber coupled single emitters, conventional diode lasers and customized AR-coated diode laser bars. With the new diode laser driver, a peak output power of 250 W can be achieved with pulse durations of approx. 100 ns. Polarization coupling of two bars increases the power by a factor of two. Thereby an output power of 500 W can be demonstrated. These systems reach an intensity of 27 MW/cm2 per diode laser bar which is sufficient for ablating processes. We will demonstrate the design of the prototype system as well as results of marking and coating removal experiments with the system.

  6. Solar oxidation and removal of arsenic--Key parameters for continuous flow applications.

    Science.gov (United States)

    Gill, L W; O'Farrell, C

    2015-12-01

    Solar oxidation to remove arsenic from water has previously been investigated as a batch process. This research has investigated the kinetic parameters for the design of a continuous flow solar reactor to remove arsenic from contaminated groundwater supplies. Continuous flow recirculated batch experiments were carried out under artificial UV light to investigate the effect of different parameters on arsenic removal efficiency. Inlet water arsenic concentrations of up to 1000 μg/L were reduced to below 10 μg/L requiring 12 mg/L iron after receiving 12 kJUV/L radiation. Citrate however was somewhat surprisingly found to promote a detrimental effect on the removal process in the continuous flow reactor studies which is contrary to results found in batch scale tests. The impact of other typical water groundwater quality parameters (phosphate and silica) on the process due to their competition with arsenic for photooxidation products revealed a much higher sensitivity to phosphate ions compared to silicate. Other results showed no benefit from the addition of TiO2 photocatalyst but enhanced arsenic removal at higher temperatures up to 40 °C. Overall, these results have indicated the kinetic envelope from which a continuous flow SORAS single pass system could be more confidently designed for a full-scale community groundwater application at a village level.

  7. Application of stereology for two-phase flow structure validation in fluidized bed reactors

    Directory of Open Access Journals (Sweden)

    Anweiler Stanisław

    2016-01-01

    Full Text Available Paper describes a novel method for two-phase gas-solid flow structure validation in fluidized bed reactors. Investigation is based on application of stereology techniques. This is an innovative approach in the field of fluidization phenomena research. Study is focused on the analysis of flow structure images, obtained with high-speed visualization of the fluidization process. Fluidization is conducted in transparent narrow channel, where plastic balls are fluidized by air. Applied stereological analysis is grounded on the linear method and on the method of random and directed secants. This enables 2-dimensional image measurement and 3-dimensional stereological extrapolation. The major result is that for each two-phase gas-solid flow structure a set of stereological parameters exists. This enables quantification of the process. It has been found that the observation of inter-relation of all stereological parameters, during the changing of the flow structure, can be used for system control. The basic conclusion is that knowledge about the character of the changes may be used for constant process adjustment for various two phase systems such as gas-solid or gas-liquid.

  8. Angiographic CT with intravenous contrast agent application for monitoring of intracranial flow diverting stents

    Energy Technology Data Exchange (ETDEWEB)

    Saake, Marc; Struffert, Tobias; Goelitz, Philipp; Ott, Sabine; Doerfler, Arnd [University of Erlangen-Nuremberg, Department of Neuroradiology, Erlangen (Germany); Seifert, Frank [University of Erlangen-Nuremberg, Department of Neurology, Erlangen (Germany); Ganslandt, Oliver [University of Erlangen-Nuremberg, Department of Neurosurgery, Erlangen (Germany)

    2012-07-15

    Intracranial flow diverting devices are increasingly used to treat cerebral aneurysms. A reliable, non-invasive follow-up modality would be desirable. Our aim was to compare intra-arterial digital subtraction angiography (ia DSA) to angiographic computed tomography with intravenous contrast agent application (iv ACT) in the visualisation of flow diverting devices and aneurysm lumina. Follow-up monitoring by iv ACT (n = 36) and ia DSA (n = 25) in 14 patients treated with flow diverting devices for intracranial aneurysms was evaluated retrospectively. Images were evaluated by two neuroradiologists in anonymous consensus reading regarding the device deployment, wall apposition, neck coverage of the aneurysm, opacification of the vessel and device lumen, as well as the degree of aneurysm occlusion. Corresponding ia DSA and iv ACT images were scored identically in all patients regarding the stent deployment, wall apposition and neck coverage, as well as the degree of aneurysm occlusion and patency status of the device and parent artery. Opacification of the parent vessel lumen and perfused parts of the aneurysm was considered slightly inferior for iv ACT in comparison with ia DSA (seven of 36 cases), without impact on diagnosis. We demonstrated the feasibility and diagnostic value of iv ACT in follow-up imaging of intracranial flow diverting devices. Due to its high spatial resolution and non-invasive character, this novel technique might become a valuable imaging modality in these patients. (orig.)

  9. Reactive fluid flow models and applications to diagenesis, mineral deposits and crustal rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lasaga, A.C.; Rye, D.M.

    1993-08-01

    Funds are requested for a combined theoretical and field study of coupled fluid flow, heat and mass transport, and chemical reaction in hydrothermal and metamorphic systems. An existing computer code developed by the applicants which numerically treats multi-component, finite-rate reactions combined with advective and dispersive transport in one and two dimensions and which incorporates isotopic exchange and heat and mass transfer will continue to be developed and applied in a variety of geological settings. The code we have developed simultaneously solves for mass transport and reaction, thus offering a significant improvement in computational efficiency over existing ``batch`` reaction path codes. By coupling flow and chemical reaction in a hydrothermal system, we can explicitly investigate the extent to which characteristic flow-reaction paths govern the chemical evolution of the fluids in a hydrothermal system. The concept of a flow-reaction path is particularly important where certain portions of mature hydrothermal systems may exhaust the buffer capacity of the rock as the primary mineralogy is consumed. In these instances 7 fluids traversing distinct regions within the hydrothermal system may experience very different reaction histories, even where the system can be described as nearly isothermal. The study of paleo-hydrothermal systems can yield some important insights into the chemical dynamics of hydrothermal systems in general. As an example of a paleo-hydrothermal system, we have considered the geochemical evolution of ``porphyry-copper`` type mineralization.

  10. Application of Newton's optimal power flow in voltage/reactive power control

    Energy Technology Data Exchange (ETDEWEB)

    Bjelogrlic, M.; Babic, B.S. (Electric Power Board of Serbia, Belgrade (YU)); Calovic, M.S. (Dept. of Electrical Engineering, University of Belgrade, Belgrade (YU)); Ristanovic, P. (Institute Nikola Tesla, Belgrade (YU))

    1990-11-01

    This paper considers an application of Newton's optimal power flow to the solution of the secondary voltage/reactive power control in transmission networks. An efficient computer program based on the latest achievements in the sparse matrix/vector techniques has been developed for this purpose. It is characterized by good robustness, accuracy and speed. A combined objective function appropriate for various system load levels with suitable constraints, for treatment of the power system security and economy is also proposed. For the real-time voltage/reactive power control, a suboptimal power flow procedure has been derived by using the reduced set of control variables. This procedure is based on the sensitivity theory applied to the determination of zones for the secondary voltage/reactive power control and corresponding reduced set of regulating sources, whose reactive outputs represent control variables in the optimal power flow program. As a result, the optimal power flow program output becomes a schedule to be used by operators in the process of the real-time voltage/reactive power control in both normal and emergency operating states.

  11. Angiographic CT with intravenous contrast agent application for monitoring of intracranial flow diverting stents.

    Science.gov (United States)

    Saake, Marc; Struffert, Tobias; Goelitz, Philipp; Ott, Sabine; Seifert, Frank; Ganslandt, Oliver; Doerfler, Arnd

    2012-07-01

    Intracranial flow diverting devices are increasingly used to treat cerebral aneurysms. A reliable, non-invasive follow-up modality would be desirable. Our aim was to compare intra-arterial digital subtraction angiography (ia DSA) to angiographic computed tomography with intravenous contrast agent application (iv ACT) in the visualisation of flow diverting devices and aneurysm lumina. Follow-up monitoring by iv ACT (n = 36) and ia DSA (n = 25) in 14 patients treated with flow diverting devices for intracranial aneurysms was evaluated retrospectively. Images were evaluated by two neuroradiologists in anonymous consensus reading regarding the device deployment, wall apposition, neck coverage of the aneurysm, opacification of the vessel and device lumen, as well as the degree of aneurysm occlusion. Corresponding ia DSA and iv ACT images were scored identically in all patients regarding the stent deployment, wall apposition and neck coverage, as well as the degree of aneurysm occlusion and patency status of the device and parent artery. Opacification of the parent vessel lumen and perfused parts of the aneurysm was considered slightly inferior for iv ACT in comparison with ia DSA (seven of 36 cases), without impact on diagnosis. We demonstrated the feasibility and diagnostic value of iv ACT in follow-up imaging of intracranial flow diverting devices. Due to its high spatial resolution and non-invasive character, this novel technique might become a valuable imaging modality in these patients.

  12. An application of computational fluid mechanics to the air flow in an infant incubator.

    Science.gov (United States)

    Yamaguchi, T; Hanai, S; Horio, H; Hasegawa, T

    1992-01-01

    An application of the computational fluid mechanical method to the air flow in a two-dimensional model of an infant incubator was described. The air flow in a numerical model was simulated and the Navier-Stokes equations were directly solved using a finite-volume method incorporating a body-fitted coordinate system on a mini-supercomputer. The model was based on a real infant incubator, slightly simplified for the sake of computing speed, and included a model of a baby. The number of computation grids was 101 x 61 = 6161. The calculation was carried out under the condition of unsteady, starting airflow and the results were examined by the means of color graphics animation. There were several very large scale eddies in the incubator free space, and their global structure did not show strong changes once they were established. Although the global structure did not change, small scale eddies were shown to be produced around the air inlet and convected down through the free space of the incubator. From these results, we believe that assuming steady and uniform flow in the incubator may not always be relevant when considering heat loss of a baby in an incubator. The steady and uniform flow has been previously assumed either implicitly or explicitly by most of the authors.

  13. Visible laser and superluminescent diode based free space and underwater communications

    KAUST Repository

    Ooi, Boon S.

    2017-01-30

    We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

  14. Thermo-enhanced field emission from ZnO nanowires: Role of defects and application in a diode flat panel X-ray source

    Science.gov (United States)

    Zhang, Zhipeng; Chen, Daokun; Chen, Wenqing; Chen, Yicong; Song, Xiaomeng; Zhan, Runze; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

    2017-03-01

    A thermo-enhanced field emission phenomenon was observed from ZnO nanowires. The field emission current increased by almost two orders of magnitude under a constant applied electric field, and the turn-on field decreased from 6.04 MV/m to 5.0 MV/m when the temperature increased from 323 to 723 K. The Poole-Frenkel electron excitation from the defect-induced trapping centers to the conduction band under high electric fields is believed to be the primary cause of the observed phenomenon. The experimental results fit well with the proposed physical model. The field emission from ZnO nanowires with different defect concentrations further confirmed the role of defects. Using the thermo-enhanced field emission phenomenon, a diode flat panel X-ray source was demonstrated, for which the energy and dose can be separately tuned. The thermo-enhanced field emission phenomenon observed from ZnO nanowires could be an effective way to realize a large area flat panel multi-energy X-ray source.

  15. The Photoluminescent Properties of New Cationic Iridium(III Complexes Using Different Anions and Their Applications in White Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Hui Yang

    2015-09-01

    Full Text Available Three cationic iridium(III complexes [Ir(ppy2(phen][PF6] (C1, [Ir(ppy2(phen]2SiF6 (C2 and [Ir(ppy2(phen]2TiF6 (C3 (ppy: 2-phenylpyridine, phen: 1, 10-phenanthroline using different anions were synthesized and characterized by 1H Nuclear magnetic resonance (1HNMR, mass spectra (MS, Fourier transform infrared (FTIR spectra and element analysis (EA. After the ultraviolet visible (UV-vis absorption spectra, photoluminescent (PL properties and thermal properties of the complexes were investigated, complex C1 and C3 with good optical properties and high thermal stability were used in white light-emitting diodes (WLEDs as luminescence conversion materials by incorporation with 460 nm-emitting blue GaN chips. The integrative performances of the WLEDs fabricated with complex C1 and C3 are better than those fabricated with the widely used yellow phosphor Y3Al5O12:Ce3+ (YAG. The color rendering indexes of the WLEDs with C1 and C3 are 82.0 and 82.6, the color temperatures of them are 5912 K and 3717 K, and the maximum power efficiencies of them are 10.61 Lm·W−1 and 11.41 Lm·W−1, respectively.

  16. Validation and application of cavity-enhanced, near-infrared tunable diode laser absorption spectrometry for measurements of methane carbon isotopes at ambient concentrations.

    Science.gov (United States)

    Mortazavi, Behzad; Wilson, Benjamin J; Dong, Feng; Gupta, Manish; Baer, Doug

    2013-10-15

    Methane is an effective greenhouse gas but has a short residence time in the atmosphere, and therefore, reductions in emissions can alleviate its greenhouse gas warming effect within a decadal time frame. Continuous and high temporal resolution measurements of methane concentrations and carbon isotopic ratios (δ(13)CH4) can inform on mechanisms of formation, provide constraints on emissions sources, and guide future mitigation efforts. We describe the development, validation, and deployment of a cavity-enhanced, near-infrared tunable diode laser absorption spectrometry system capable of quantifying δ(13)CH4 at ambient methane concentrations. Laboratory validation and testing show that the instrument is capable of operating over a wide dynamic range of methane concentration and provides a measurement precision for δ(13)CH4 of better than ± 0.5 ‰ (1σ) over 1000 s of data averaging at ambient methane concentrations. The analyzer is accurate to better than ± 0.5 ‰, as demonstrated by measurements of characterized methane/air samples with minimal dependence (methane concentration. Deployment of the instrument at a marsh over multiple days demonstrated how methane fluxes varied by an order of magnitude over 2 day deployment periods, and showed a 17 ‰ variability in δ(13)CH4 of the emitted methane during the growing season.

  17. Synthesis of Zn(1-x)Cd(x)S:Mn/ZnS quantum dots and their application to light-emitting diodes.

    Science.gov (United States)

    Kim, Jong-Uk; Lee, Myung-Hyun; Yang, Heesun

    2008-11-19

    3.6 nm sized Mn-doped Zn(1-x)Cd(x)S quantum dots (QDs) with the composition (x) of 1, 0.5, 0.2 and 0 were synthesized by a reverse micelle approach. The bandgap energy of Zn(1-x)Cd(x)S:Mn QDs was tuned to a higher energy by increasing the Zn content, and the actual composition of alloyed Zn(1-x)Cd(x)S:Mn QDs was found to be different from the solution composition. Consecutive overcoating of the Zn(1-x)Cd(x)S:Mn QD surface by a ZnS shell was done, and the core/shell structured QDs exhibited quantum yields of 14-30%, depending on the composition of the core QDs. Using CdS:Mn/ZnS QDs, orange and white light-emitting diodes (LEDs) pumped by a near-UV and blue LED chips, respectively, were fabricated and their optical properties are described.

  18. Low Temperature DC Sputtering Deposition on Indium-Tin Oxide Film and Its Application to Inverted Top-emitting Organic Light-emitting Diodes

    Institute of Scientific and Technical Information of China (English)

    Hui LIN; Junsheng YU; Shuangling LOU; Jun WANG; Yadong JIANG

    2008-01-01

    Indium tin oxide (ITO) ultrathin films were prepared on glass substrate by DC (direct current) magnetron sputtering technique with the assistance of H2O vapor to avoid potential surface damage. The film properties were characterized by X-ray diffraction (XRD) technique, four-point probe method and spectrophotometer. The results show that the deposited ITO film with introduced H20 during sputtering process was almost amor- phous. The average visible light transmission of 100 nm ITO film was around 85% and square resistivity was below 80 Ω/square. The film was used as the transparent anode to fabricate an inverted top-emitting organic light-emitting diodes (IT-OLEDs) with the structure of glass substrate/AIq3 (40 nm)/NPB (15 nm)/CuPc(x nm)/ITO anode (100 nm), where the film thickness of CuPc was optimized. It was found that the lumi-nance of this IT-OLEDs was improved from 25 cd/m2 to more than 527 cd/m2 by increasing the thickness of CuPc, and luminance efficiency of 0.24 lm/W at 100 cd/m2 was obtained, which indicated that the optimized thickness of CuPc layer was around 15 nm.

  19. Application of the diode laser for welding in tairoled blanks; Aplicaciond el lase de diodo para la soldadura en tailored blanks

    Energy Technology Data Exchange (ETDEWEB)

    Bocos, J. L.; Zubiri, F.; Garciandia, F.; Pena, J.; Cortiella, A.; Berrueta, J. M.; Zapirain, F.

    2004-07-01

    During the last years, one of the most interesting subjects in the automotive industry is the weight reduction of the automobile, and so to diminish the fuel consumption. Among other performance, the use in the body car of materials which have high mechanical resistance must be considered for the weight reduction of the automobile and maintaining high benefits. In this work, it has been studied the utilization of the diode laser for high resistance steel sheets welding, concretely microalloying steels (ZStE), DP dual phase and TRIP transformation induced plasticity. These steels can be employed in tailored blanks, which are defined as two or more separate pieces of flat material of dissimilar thickness and/or physical properties joined together before forming, to provide superior qualities in the finished stamped part. In this study, the metallographic characterization has been realised in the welding seams, and the mechanical behaviour has been analysed employing the following tests: microhardenss, drawing, tensile and fatigue. (Author) 15 refs.

  20. Photo- and electroluminescent properties of bithiophene disubstituted 1,3,4-thiadiazoles and their application as active components in organic light emitting diodes

    Science.gov (United States)

    Grykien, Remigiusz; Luszczynska, Beata; Glowacki, Ireneusz; Kurach, Ewa; Rybakiewicz, Renata; Kotwica, Kamil; Zagorska, Malgorzata; Pron, Adam; Tassini, Paolo; Maglione, Maria Grazia; Mauro, Anna De Girolamo Del; Fasolino, Tommaso; Rega, Romina; Pandolfi, Giuseppe; Minarini, Carla; Aprano, Salvatore

    2014-11-01

    Photo- and electroluminescence of five bithiophene disubstituted 1,3,4-thiadiazoles, constituting a new class of solution processable materials for organic opto-electronics, were studied. It was found that the introduction of alkyl solubilizing substituents bathochromically shifted the photo- and electroluminescence bands. The most pronounced effect was observed for the substitution at the Cα position which changed the emitting light color from bluish to green. All five derivatives were tested in host/guest type organic light emitting diodes (OLEDs) with either poly(N-vinylcarbazole) (PVK) or poly(N-vinylcarbazole) + 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PVK + PBD) matrices. The latter matrix turned out especially well suited for these guest molecules yielding devices of varying color coordinates. The best luminance (750 cd/m2) was measured for 2,5-bis(5‧-octyl-2,2‧-bithiophene-5-yl)-1,3,4-thiadiazole with the luminous efficiency exceeding 0.4 cd/A.