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Sample records for switching diodes

  1. Microstrip PIN diode microwave switch

    OpenAIRE

    Usanov, Dmitry A.; Skripal, A. V.; Kulikov, M. Yu.

    2011-01-01

    A possibility of creating narrow-band electrically controlled microwave breakers and switches with enhanced attenuation level in the blocking mode has been considered. The specified devices are based on the structure containing a short-circuited microstrip link with connected capacitor and the loop coupler, in the center of which is located a PIN diode.

  2. A CW Gunn diode bistable switching element.

    Science.gov (United States)

    Hurtado, M.; Rosenbaum, F. J.

    1972-01-01

    Experiments with a current-controlled bistable switching element using a CW Gunn diode are reported. Switching rates of the order of 10 MHz have been obtained. Switching is initiated by current pulses of short duration (5-10 ns). Rise times of the order of several nanoseconds could be obtained.

  3. Proto-I switching and diode studies

    International Nuclear Information System (INIS)

    Prestwich, K.R.; Miller, P.A.; McDaniel, D.H.; Poukey, J.W.; Widner, M.M.; Goldstein, S.A.

    1975-01-01

    Proto-I is a 3 MV, 800 kA, 24 ns electron beam accelerator that is under development at Sandia Laboratories. It represents an initial effort to develop a scalable technology that is applicable to accelerators for electron beam driven, inertial confinement fusion studies. Energy is supplied to each of the two diodes from six oil-dielectric Blumlein transmission lines (PFL) operating in parallel. A Marx generator charges three intermediate storage, water-dielectric capacitors which subsequently transfer the stored energy to the PFL. The discharge of the PFL is initiated by the simultaneous closure of 12 triggered oil-dielectric rail switches. Data will be presented on the operation of these multichannel switches. The two diodes have a common anode. Cathode diameters can be varied from 10 to 60 cm. Results of initial diode experiments and comparisons with theory are discussed. Plasma filled diode experiments are also reported, indicating pinch collapse velocities in excess of 10 9 cm/s

  4. Mathematical modeling of a passively Q-switched diode laser

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.

    2009-11-01

    A mathematical model describing the dynamic emission of the intracavity frequency doubling (IFD) of a gain-switched InGaAs/GaAs/KTP and a gain-switched mode-locked two-sections tapered ridge-waveguide InGaAs/GaAs diode laser has been presented. The IFD of a gain-switched and a gain-switched mode-locked two-sections diode laser is modeled where one section is electrically pumped to proved gain while the second section is unpumped (reverse biased) to provide a saturable absorber. (author)

  5. Comparison of MEMS switches and PIN diodes for switched dual tuned RF coils.

    Science.gov (United States)

    Maunder, Adam; Rao, Madhwesha; Robb, Fraser; Wild, Jim M

    2018-03-09

    To evaluate the performance of micro-electromechanical systems (MEMS) switches against PIN diodes for switching a dual-tuned RF coil between 19 F and 1 H resonant frequencies for multi-nuclear lung imaging. A four-element fixed-phase and amplitude transmit-receive RF coil was constructed to provide homogeneous excitation across the lungs, and to serve as a test system for various switching methods. The MR imaging and RF performance of the coil when switched between the 19 F and 1 H frequencies using MEMS switches, PIN diodes and hardwired configurations were compared. The performance of the coil with MEMS or PIN diode switching was comparable in terms of RF measurements, transmit efficiency and image SNR on both 19 F and 1 H nuclei. When the coil was not switched to the resonance frequency of the respective nucleus being imaged, reductions in the transmit efficiency were observed of 32% at the 19 F frequency and 12% at the 1 H frequency. The coil provides transmit field homogeneity of ±12.9% at the 1 H frequency and ±14.4% at the 19 F frequency in phantoms representing the thorax with the air space of the lungs filled with perfluoropropane gas. MEMS and PIN diodes were found to provide comparable performance in on-state configuration, while MEMS were more robust in off-state high-powered operation (>1 kW), providing higher isolation and requiring a lower DC switching voltage than is needed for reverse biasing of PIN diodes. In addition, clear benefits of switching between the 19 F and 1 H resonances were demonstrated, despite the proximity of their Larmor frequencies. © 2018 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

  6. Millimeter wave p—i—n-diode switching controlled devices

    Directory of Open Access Journals (Sweden)

    Karushkin N. F.

    2016-10-01

    Full Text Available The paper presents the results of research and development of concentrated type p—i—n-diodes switches providing the switching time units of nanoseconds. To increase lock losses of (~40 dB the authors use a cascade connection of diodes into waveguide and microstrip transmission line of θ = π/2 electric length. Investigation results of creation of switching devices using longitudinally and transversely-distributed p—i—n-structures in the shortwave part of the millimeter wavelength range (f = 300 GHz are presented. When developing switching devices intended to control the level of microwave power in the millimeter wavelength range, a number of special features arise limiting the achievement of optimal parameters. The dimensions of the metal ceramic packaged p—i—n-diodes and the mounting elements of semiconductor structures become comparable with the wavelength. As a result, package cannot be considered in the calculations and in the design as the capacity of the concentrated type. In our case the diode package is considered in the form of radial line which is able to transform the input impedance of the transmission line to the terminals of the diode structures, and realize high-impedance state (parallel resonance in the device circuit in the mode of microwave power transmission. Engineering calculations for the given parameters of the silicon mesostructures showed the possibility of creating high-speed devices for switching microwave power with good characteristics. For diode assembling industrial clockwork ruby jewels with high quality of surface finish, strength and appropriate dimensions are applied as dielectric bushings. Suffice it to say that in the frequency range of 150 GHz, we used the bushings with dimensions of external diameter D = 0.4 mm and a height of h = 0.15 mm. The switches created provide transient units of nanoseconds, isolation more than 40 dB at relative frequency bandwidth of 30-40%. Evaluating progress in the

  7. Monolayer MoS{sub 2} self-switching diodes

    Energy Technology Data Exchange (ETDEWEB)

    Al-Dirini, Feras, E-mail: alf@unimelb.edu.au; Hossain, Md Sharafat [Department of Electrical and Electronic Engineering, University of Melbourne, Victoria (Australia); Centre for Neural Engineering, University of Melbourne, Victoria (Australia); Victorian Research Laboratory, National ICT Australia, West Melbourne, Victoria (Australia); Hossain, Faruque M.; Skafidas, Efstratios [Department of Electrical and Electronic Engineering, University of Melbourne, Victoria (Australia); Centre for Neural Engineering, University of Melbourne, Victoria (Australia); Mohammed, Mahmood A. [Princess Sumaya University for Technology, Amman (Jordan); Nirmalathas, Ampalavanapillai [Department of Electrical and Electronic Engineering, University of Melbourne, Victoria (Australia); Melbourne Networked Society Institute (MNSI), University of Melbourne, Victoria (Australia)

    2016-01-28

    This paper presents a new molybdenum disulphide (MoS{sub 2}) nanodevice that acts as a two-terminal field-effect rectifier. The device is an atomically-thin two-dimensional self-switching diode (SSD) that can be realized within a single MoS{sub 2} monolayer with very minimal process steps. Quantum simulation results are presented confirming the device's operation as a diode and showing strong non-linear I-V characteristics. Interestingly, the device shows p-type behavior, in which conduction is dominated by holes as majority charge carriers and the flow of reverse current is enhanced, while the flow of forward current is suppressed, in contrast to monolayer graphene SSDs, which behave as n-type devices. The presence of a large bandgap in monolayer MoS{sub 2} results in strong control over the channel, showing complete channel pinch-off in forward conduction, which was confirmed with transmission pathways plots. The device exhibited large leakage tunnelling current through the insulating trenches, which may have been due to the lack of passivation; nevertheless, reverse current remained to be 6 times higher than forward current, showing strong rectification. The effect of p-type substitutional channel doping of sulphur with phosphorus was investigated and showed that it greatly enhances the performance of the device, increasing the reverse-to-forward current rectification ratio more than an order of magnitude, up to a value of 70.

  8. Monolayer MoS2 self-switching diodes

    International Nuclear Information System (INIS)

    Al-Dirini, Feras; Hossain, Md Sharafat; Hossain, Faruque M.; Skafidas, Efstratios; Mohammed, Mahmood A.; Nirmalathas, Ampalavanapillai

    2016-01-01

    This paper presents a new molybdenum disulphide (MoS 2 ) nanodevice that acts as a two-terminal field-effect rectifier. The device is an atomically-thin two-dimensional self-switching diode (SSD) that can be realized within a single MoS 2 monolayer with very minimal process steps. Quantum simulation results are presented confirming the device's operation as a diode and showing strong non-linear I-V characteristics. Interestingly, the device shows p-type behavior, in which conduction is dominated by holes as majority charge carriers and the flow of reverse current is enhanced, while the flow of forward current is suppressed, in contrast to monolayer graphene SSDs, which behave as n-type devices. The presence of a large bandgap in monolayer MoS 2 results in strong control over the channel, showing complete channel pinch-off in forward conduction, which was confirmed with transmission pathways plots. The device exhibited large leakage tunnelling current through the insulating trenches, which may have been due to the lack of passivation; nevertheless, reverse current remained to be 6 times higher than forward current, showing strong rectification. The effect of p-type substitutional channel doping of sulphur with phosphorus was investigated and showed that it greatly enhances the performance of the device, increasing the reverse-to-forward current rectification ratio more than an order of magnitude, up to a value of 70

  9. Ultra-Fast All-Optical Self-Aware Protection Switching Based on a Bistable Laser Diode

    DEFF Research Database (Denmark)

    An, Yi; Vukovic, Dragana; Lorences Riesgo, Abel

    2014-01-01

    We propose a novel concept of all-optical protection switching with link failure automatic awareness based on AOWFF. The scheme is experimentally demonstrated using a single MG-Y laser diode with a record switching time ~200 ps....

  10. Diode array pumped, non-linear mirror Q-switched and mode-locked ...

    Indian Academy of Sciences (India)

    Abstract. A non-linear mirror consisting of a lithium triborate crystal and a dichroic output coupler are used to mode-lock (passively) an Nd : YVO4 laser, pumped by a diode laser array. The laser can operate both in cw mode-locked and simultaneously Q-switched and mode-locked (QML) regime. The peak power of the laser ...

  11. Diode array pumped, non-linear mirror Q-switched and mode-locked ...

    Indian Academy of Sciences (India)

    A non-linear mirror consisting of a lithium triborate crystal and a dichroic output coupler are used to mode-lock (passively) an Nd : YVO4 laser, pumped by a diode laser array. The laser can operate both in cw mode-locked and simultaneously Q-switched and mode-locked (QML) regime. The peak power of the laser while ...

  12. Diode array pumped, non-linear mirror Q-switched and mode-locked

    Indian Academy of Sciences (India)

    A non-linear mirror consisting of a lithium triborate crystal and a dichroic output coupler are used to mode-lock (passively) an Nd : YVO4 laser, pumped by a diode laser array. The laser can operate both in cw mode-locked and simultaneously Q-switched and mode-locked (QML) regime. The peak power of the laser while ...

  13. Graphene-Based Reversible Nano-Switch/Sensor Schottky Diode

    Science.gov (United States)

    Miranda, Felix A.; Meador, Michael A.; Theofylaktos, Onoufrios; Pinto, Nicholas J.; Mueller, Carl H.; Santos-Perez, Javier

    2010-01-01

    This proof-of-concept device consists of a thin film of graphene deposited on an electrodized doped silicon wafer. The graphene film acts as a conductive path between a gold electrode deposited on top of a silicon dioxide layer and the reversible side of the silicon wafer, so as to form a Schottky diode. By virtue of the two-dimensional nature of graphene, this device has extreme sensitivity to different gaseous species, thereby serving as a building block for a volatile species sensor, with the attribute of having reversibility properties. That is, the sensor cycles between active and passive sensing states in response to the presence or absence of the gaseous species.

  14. Robust random number generation using steady-state emission of gain-switched laser diodes

    International Nuclear Information System (INIS)

    Yuan, Z. L.; Lucamarini, M.; Dynes, J. F.; Fröhlich, B.; Plews, A.; Shields, A. J.

    2014-01-01

    We demonstrate robust, high-speed random number generation using interference of the steady-state emission of guaranteed random phases, obtained through gain-switching a semiconductor laser diode. Steady-state emission tolerates large temporal pulse misalignments and therefore significantly improves the interference quality. Using an 8-bit digitizer followed by a finite-impulse-response unbiasing algorithm, we achieve random number generation rates of 8 and 20 Gb/s, for laser repetition rates of 1 and 2.5 GHz, respectively, with a ±20% tolerance in the interferometer differential delay. We also report a generation rate of 80 Gb/s using partially phase-correlated short pulses. In relation to the field of quantum key distribution, our results confirm the gain-switched laser diode as a suitable light source, capable of providing phase-randomized coherent pulses at a clock rate of up to 2.5 GHz.

  15. Diode-end-pumped single-longitudinal-mode passively Q-switched Nd:GGG laser

    Science.gov (United States)

    Xue, Feng; Zhang, Sasa; Cong, Zhenhua; Huang, Qingjie; Guan, Chen; Wu, Qianwen; Chen, Hui; Bai, Fen; Liu, Zhaojun

    2018-03-01

    Diode-end-pumped passively Q-switched Nd:GGG laser in a ring cavity at 1062 nm was demonstrated. Single-longitudinal-mode laser linewidth less than 0.5 pm was accomplished by unidirectional operation. The maximum output pulse energy was 437 µJ and the pulse width was 43 ns when Cr4+:YAG with an initial transmission of 61% was used.

  16. Diode-pumped Alexandrite laser with passive SESAM Q-switching and wavelength tunability

    Science.gov (United States)

    Parali, Ufuk; Sheng, Xin; Minassian, Ara; Tawy, Goronwy; Sathian, Juna; Thomas, Gabrielle M.; Damzen, Michael J.

    2018-03-01

    We report the first experimental demonstration of a wavelength tunable passively Q-switched red-diode-end pumped Alexandrite laser using a semiconductor saturable absorber mirror (SESAM). We present the results of the study of passive SESAM Q-switching and wavelength-tuning in continuous diode-pumped Alexandrite lasers in both linear cavity and X-cavity configurations. In the linear cavity configuration, pulsed operation up to 27 kHz repetition rate in fundamental TEM00 mode was achieved and maximum average power was 41 mW. The shortest pulse generated was 550 ns (FWHM) and the Q-switched wavelength tuning band spanned was between 740 nm and 755 nm. In the X-cavity configuration, a higher average power up to 73 mW, and obtained with higher pulse energy 6 . 5 μJ at 11.2 kHz repetition rate, in fundamental TEM00 mode with excellent spatial quality M2 < 1 . 1. The Q-switched wavelength tuning band spanned was between 775 nm and 781 nm.

  17. An overview of self-switching diode rectifiers using green materials

    Science.gov (United States)

    Kasjoo, Shahrir Rizal; Zailan, Zarimawaty; Zakaria, Nor Farhani; Isa, Muammar Mohamad; Arshad, Mohd Khairuddin Md; Taking, Sanna

    2017-09-01

    A unipolar two-terminal nanodevice, known as the self-switching diode (SSD), has recently been demonstrated as a room-temperature rectifier at microwave and terahertz frequencies due to its nonlinear current-voltage characteristic. The planar architecture of SSD not only makes the fabrication process of the device faster, simpler and at a lower cost when compared with other rectifying diodes, but also allows the use of various materials to realize and fabricate SSDs. This includes the utilization of `green' materials such as organic and graphene thin films for environmental sustainability. This paper reviews the properties of current `green' SSD rectifiers with respect to their operating frequencies and rectifying performances, including responsivity and noise-equivalent power of the devices, along with the applications.

  18. Efficient energy extraction from a diode-pumped Q-switched Tm,Ho:YLiF4 laser

    Science.gov (United States)

    Mcguckin, B. T.; Menzies, R. T.; Hemmati, H.

    1991-01-01

    The operation of a diode-laser pumped thulium, holmium yttrium-lithium-fluoride laser (Tm,Ho:YLF) in Q-switched mode is reported. Output energies of 200 microjoules in pulses of 22 ns duration are recorded at Q-switch frequencies commensurate with an effective upper laser level lifetime of 6 ms. This lifetime is appreciably longer than that observed in other hosts permitting stored energy extraction of 64 percent, close to the projected maximum performance from these materials.

  19. Investigation of Power Flow from a Plasma Opening Switch to an Electron Beam Diode

    National Research Council Canada - National Science Library

    Black, D

    1999-01-01

    ...) and an electron-beam (e-beam) diode load. The parameters that were varied independently in this set of experiments were the conduction time, the e-beam diode anode-cathode (A-K) gap (diode impedance...

  20. High power gain switched laser diodes using a novel compact picosecond switch based on a GaAs bipolar junction transistor structure for pumping

    Science.gov (United States)

    Vainshtein, Sergey; Kostamovaara, Juha

    2006-04-01

    A number of up-to-date applications, including advanced optical radars with high single-shot resolution, precise 3 D imaging, laser tomography, time imaging spectroscopy, etc., require low-cost, compact, reliable sources enabling the generation of high-power (1-100 W) single optical pulses in the picosecond range. The well-known technique of using the gain-switching operation mode of laser diodes to generate single picosecond pulses in the mW range fails to generate high-power single picosecond pulses because of a lack of high-current switches operating in the picosecond range. We report here on the achieving of optical pulses of 45W / 70ps, or alternatively 5W / 40ps, with gain-switched commercial quantum well (QW) laser diodes having emitting areas of 250 × 200 μm and 75 × 2 μm, respectively. This was made possible by the use of a novel high-current avalanche switch based on a GaAs bipolar junction transistor (BJT) structure with a switching time (transistor structure.) A simulation code developed earlier but modified and carefully verified here allowed detailed comparison of the experimental and simulated laser responses and the transient spectrum.

  1. Integrated one diode-one resistor architecture in nanopillar SiOx resistive switching memory by nanosphere lithography.

    Science.gov (United States)

    Ji, Li; Chang, Yao-Feng; Fowler, Burt; Chen, Ying-Chen; Tsai, Tsung-Ming; Chang, Kuan-Chang; Chen, Min-Chen; Chang, Ting-Chang; Sze, Simon M; Yu, Edward T; Lee, Jack C

    2014-02-12

    We report on a highly compact, one diode-one resistor (1D-1R) nanopillar device architecture for SiOx-based ReRAM fabricated using nanosphere lithography (NSL). The intrinsic SiOx-based resistive switching element and Si diode are self-aligned on an epitaxial silicon wafer using NSL and a deep-Si-etch process without conventional photolithography. AC-pulse response in 50 ns regime, multibit operation, and good reliability are demonstrated. The NSL process provides a fast and economical approach to large-scale patterning of high-density 1D-1R ReRAM with good potential for use in future applications.

  2. Rectification of graphene self-switching diodes: First-principles study

    Science.gov (United States)

    Ghaziasadi, Hassan; Jamasb, Shahriar; Nayebi, Payman; Fouladian, Majid

    2018-05-01

    The first principles calculations based on self-consistent charge density functional tight-binding have performed to investigate the electrical properties and rectification behavior of the graphene self-switching diodes (GSSD). The devices contained two structures called CG-GSSD and DG-GSSD which have metallic or semiconductor gates depending on their side gates have a single or double hydrogen edge functionalized. We have relaxed the devices and calculated I-V curves, transmission spectrums and maximum rectification ratios. We found that the DG-MSM devices are more favorable and more stable. Also, the DG-MSM devices have better maximum rectification ratios and current. Moreover, by changing the side gates widths and behaviors from semiconductor to metal, the threshold voltages under forward bias changed from +1.2 V to +0.3 V. Also, the maximum currents are obtained from 1.12 μA to 10.50 μA. Finally, the MSM and SSS type of all devices have minimum and maximum values of voltage threshold and maximum rectification ratios, but the 769-DG devices don't obey this rule.

  3. Coexistence of diode-like volatile and multilevel nonvolatile resistive switching in a ZrO2/TiO2 stack structure.

    Science.gov (United States)

    Li, Yingtao; Yuan, Peng; Fu, Liping; Li, Rongrong; Gao, Xiaoping; Tao, Chunlan

    2015-10-02

    Diode-like volatile resistive switching as well as nonvolatile resistive switching behaviors in a Cu/ZrO₂/TiO₂/Ti stack are investigated. Depending on the current compliance during the electroforming process, either volatile resistive switching or nonvolatile resistive switching is observed. With a lower current compliance (volatile resistive switching with a rectifying ratio over 10(6). The permanent transition from volatile to nonvolatile resistive switching can be obtained by applying a higher current compliance of 100 μA. Furthermore, by using different reset voltages, the Cu/ZrO₂/TiO₂/Ti device exhibits multilevel memory characteristics with high uniformity. The coexistence of nonvolatile multilevel memory and diode-like volatile resistive switching behaviors in the same Cu/ZrO₂/TiO₂/Ti device opens areas of applications in high-density storage, logic circuits, neural networks, and passive crossbar memory selectors.

  4. Experimental determination of quantum-well lifetime effect on large-signal resonant tunneling diode switching time

    Energy Technology Data Exchange (ETDEWEB)

    Growden, Tyler A.; Berger, Paul R., E-mail: pberger@ieee.org [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Brown, E. R.; Zhang, Weidong [Departments of Physics and Electrical Engineering, Wright State University, Dayton, Ohio 45435 (United States); Droopad, Ravi [Ingram School of Engineering, Texas State University, San Marcos, Texas 78666 (United States)

    2015-10-12

    An experimental determination is presented of the effect the quantum-well lifetime has on a large-signal resonant tunneling diode (RTD) switching time. Traditional vertical In{sub 0.53}Ga{sub 0.47}As/AlAs RTDs were grown, fabricated, and characterized. The switching time was measured with a high-speed oscilloscope and found to be close to the sum of the calculated RC-limited 10%–90% switching time and the quantum-well quasibound-state lifetime. This method displays experimental evidence that the two intrinsic resonant-tunneling characteristic times act independently, and that the quasibound-state lifetime then serves as a quantum-limit on the large-signal speed of RTDs.

  5. Structure of picosecond pulses of a Q-switched and mode-locked diode-pumped Nd:YAG laser

    Science.gov (United States)

    Donin, V. I.; Yakovin, D. V.; Gribanov, A. V.

    2015-12-01

    The pulse duration of a diode-pumped Nd:YAG laser, in which Q-switching with mode-locking (QML regime) is achieved using a spherical mirror and a travelling-wave acousto-optic modulator, is directly measured with a streak camera. It is found that the picosecond pulses can have a non-single-pulse structure, which is explained by excitation of several competing transverse modes in the Q-switching regime with a pulse repetition rate of 1 kHz. In the case of cw mode-locking (without Q-switching), a new (auto-QML) regime is observed, in which the pulse train repetition rate is determined by the frequency of the relaxation oscillations of the laser field while the train contains single picosecond pulses.

  6. Structure of picosecond pulses of a Q-switched and mode-locked diode-pumped Nd:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Donin, V I; Yakovin, D V; Gribanov, A V [Institute of Automation and Electrometry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2015-12-31

    The pulse duration of a diode-pumped Nd:YAG laser, in which Q-switching with mode-locking (QML regime) is achieved using a spherical mirror and a travelling-wave acousto-optic modulator, is directly measured with a streak camera. It is found that the picosecond pulses can have a non-single-pulse structure, which is explained by excitation of several competing transverse modes in the Q-switching regime with a pulse repetition rate of 1 kHz. In the case of cw mode-locking (without Q-switching), a new (auto-QML) regime is observed, in which the pulse train repetition rate is determined by the frequency of the relaxation oscillations of the laser field while the train contains single picosecond pulses. (control of laser radiation parameters)

  7. Analysis of dynamic characteristics of SiC Schottky barrier diodes at high switching frequency based on junction capacitance

    Science.gov (United States)

    Maeda, Ryosuke; Okuda, Takafumi; Hikihara, Takashi

    2018-04-01

    In this paper, we focus on relationships between dynamic characteristics and device structures of SiC Schottky barrier diodes (SBDs) to investigate their switching capabilities. A device model based on junction capacitance and thermionic emission theory is proposed. To measure the dynamic characteristics of SiC SBD, a high-frequency (10 MHz) and high-voltage (200 Vpp) wave generator is fabricated. By comparing simulated results with experimental results, it is found that the proposed model can represent the dynamic characteristics at 10 MHz and 200 °C, and the simple device model based on junction capacitance and thermionic emission theory well describes the switching behaviors of SiC SBDs at full operational temperature. The proposed device model is beneficial for designing high-power converters, at both wide temperature and wide frequency ranges.

  8. The Switch from Low-Pressure Sodium to Light Emitting Diodes Does Not Affect Bat Activity at Street Lights.

    Directory of Open Access Journals (Sweden)

    Elizabeth G Rowse

    Full Text Available We used a before-after-control-impact paired design to examine the effects of a switch from low-pressure sodium (LPS to light emitting diode (LED street lights on bat activity at twelve sites across southern England. LED lights produce broad spectrum 'white' light compared to LPS street lights that emit narrow spectrum, orange light. These spectral differences could influence the abundance of insects at street lights and thereby the activity of the bats that prey on them. Most of the bats flying around the LPS lights were aerial-hawking species, and the species composition of bats remained the same after the switch-over to LED. We found that the switch-over from LPS to LED street lights did not affect the activity (number of bat passes, or the proportion of passes containing feeding buzzes, of those bat species typically found in close proximity to street lights in suburban environments in Britain. This is encouraging from a conservation perspective as many existing street lights are being, or have been, switched to LED before the ecological consequences have been assessed. However, lighting of all spectra studied to date generally has a negative impact on several slow-flying bat species, and LED lights are rarely frequented by these 'light-intolerant' bat species.

  9. The Switch from Low-Pressure Sodium to Light Emitting Diodes Does Not Affect Bat Activity at Street Lights

    Science.gov (United States)

    Rowse, Elizabeth G.; Harris, Stephen; Jones, Gareth

    2016-01-01

    We used a before-after-control-impact paired design to examine the effects of a switch from low-pressure sodium (LPS) to light emitting diode (LED) street lights on bat activity at twelve sites across southern England. LED lights produce broad spectrum ‘white’ light compared to LPS street lights that emit narrow spectrum, orange light. These spectral differences could influence the abundance of insects at street lights and thereby the activity of the bats that prey on them. Most of the bats flying around the LPS lights were aerial-hawking species, and the species composition of bats remained the same after the switch-over to LED. We found that the switch-over from LPS to LED street lights did not affect the activity (number of bat passes), or the proportion of passes containing feeding buzzes, of those bat species typically found in close proximity to street lights in suburban environments in Britain. This is encouraging from a conservation perspective as many existing street lights are being, or have been, switched to LED before the ecological consequences have been assessed. However, lighting of all spectra studied to date generally has a negative impact on several slow-flying bat species, and LED lights are rarely frequented by these ‘light-intolerant’ bat species. PMID:27008274

  10. Design and construction of a novel1H/19F double-tuned coil system using PIN-diode switches at 9.4T.

    Science.gov (United States)

    Choi, Chang-Hoon; Hong, Suk-Min; Ha, YongHyun; Shah, N Jon

    2017-06-01

    A double-tuned 1 H/ 19 F coil using PIN-diode switches was developed and its performance evaluated. The is a key difference from the previous developments being that this design used a PIN-diode switch in series with an additionally inserted inductor in parallel to one of the capacitors on the loop. The probe was adjusted to 19 F when the reverse bias voltage was applied (PIN-diode OFF), whilst it was switched to 1 H when forward current was flowing (PIN-diode ON). S-parameters and Q-factors of single- and double-tuned coils were examined and compared with/without a phantom on the bench. Imaging experiments were carried out on a 9.4T preclinical scanner. All coils were tuned at resonance frequencies and matched well. It is shown that the Q-ratio and SNR of double-tuned coil at 19 F frequency are nearly as good as those of a single-tuned coil. Since the operating frequency was tuned to 19 F when the PIN-diodes were turned off, losses due to PIN-diodes were substantially lower resulting in the provision of excellent image quality of X-nuclei. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Design and construction of a novel 1H/19F double-tuned coil system using PIN-diode switches at 9.4 T

    Science.gov (United States)

    Choi, Chang-Hoon; Hong, Suk-Min; Ha, YongHyun; Shah, N. Jon

    2017-06-01

    A double-tuned 1H/19F coil using PIN-diode switches was developed and its performance evaluated. The is a key difference from the previous developments being that this design used a PIN-diode switch in series with an additionally inserted inductor in parallel to one of the capacitors on the loop. The probe was adjusted to 19F when the reverse bias voltage was applied (PIN-diode OFF), whilst it was switched to 1H when forward current was flowing (PIN-diode ON). S-parameters and Q-factors of single- and double-tuned coils were examined and compared with/without a phantom on the bench. Imaging experiments were carried out on a 9.4 T preclinical scanner. All coils were tuned at resonance frequencies and matched well. It is shown that the Q-ratio and SNR of double-tuned coil at 19F frequency are nearly as good as those of a single-tuned coil. Since the operating frequency was tuned to 19F when the PIN-diodes were turned off, losses due to PIN-diodes were substantially lower resulting in the provision of excellent image quality of X-nuclei.

  12. Coexistence of diode-like volatile and multilevel nonvolatile resistive switching in a ZrO2/TiO2 stack structure

    International Nuclear Information System (INIS)

    Li, Yingtao; Yuan, Peng; Li, Rongrong; Tao, Chunlan; Fu, Liping; Gao, Xiaoping

    2015-01-01

    Diode-like volatile resistive switching as well as nonvolatile resistive switching behaviors in a Cu/ZrO 2 /TiO 2 /Ti stack are investigated. Depending on the current compliance during the electroforming process, either volatile resistive switching or nonvolatile resistive switching is observed. With a lower current compliance (<10 μA), the Cu/ZrO 2 /TiO 2 /Ti device exhibits diode-like volatile resistive switching with a rectifying ratio over 10 6 . The permanent transition from volatile to nonvolatile resistive switching can be obtained by applying a higher current compliance of 100 μA. Furthermore, by using different reset voltages, the Cu/ZrO 2 /TiO 2 /Ti device exhibits multilevel memory characteristics with high uniformity. The coexistence of nonvolatile multilevel memory and diode-like volatile resistive switching behaviors in the same Cu/ZrO 2 /TiO 2 /Ti device opens areas of applications in high-density storage, logic circuits, neural networks, and passive crossbar memory selectors. (fast track communication)

  13. Fabrication of poly(3-hexylthiophene) self-switching diodes using thermal nanoimprint lithography and argon milling

    Czech Academy of Sciences Publication Activity Database

    Kettle, J.; Whitelegg, S.; Song, M.; Madec, M. B.; Yeates, S.; Turner, M. L.; Kotačka, L.; Kolařík, Vladimír

    2009-01-01

    Roč. 27, č. 6 (2009), s. 2801-2804 ISSN 1071-1023 R&D Projects: GA ČR GA102/05/2325 Institutional research plan: CEZ:AV0Z20650511 Keywords : argon * milling * nanolithography * organic semiconductors * semiconductor diodes Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.460, year: 2009

  14. Diode Dynamics, Beam Generation and Transport and Plasma Erosion Opening Switch Development.

    Science.gov (United States)

    1983-05-17

    mo :f.? .S, j Camara SIMFOLt.N t io o SSC I,,LOOP FIG. 4. Schematic diagramn of a planar pinch reflex diode, the drift tube,.3a1d FIG 5...and depend on such variables as plasma temperature, gas composition, impurity Q 11 surprising that the shapes of the calculated prompt- gama responses

  15. Diode-pumped passively Q-switched Nd:GGG laser with a Bi-doped GaAs semiconductor saturable absorber

    Science.gov (United States)

    Cong, Wen; Li, Dechun; Zhao, Shengzhi; Yang, Kejian; Li, Xiangyang; Qiao, Hui; Liu, Ji

    2014-12-01

    Passive Q-switching of a diode-pumped Nd:GGG laser is demonstrated using Bi-doped GaAs as saturable absorber. The Bi-doped GaAs wafer is fabricated by ion implantation and subsequent annealing. Compared with the Q-switched laser by undoped GaAs semiconductor saturable absorber, the laser with Bi-doped GaAs as saturable absorber can produce higher output power, shorter pulses, higher single pulse energies and higher peak powers. These results suggest that Bi-doped GaAs can be a promising new candidate of semiconductor saturable absorber in Q-switched laser.

  16. 5.8kV SiC PiN Diode for Switching of High-Efficiency Inductive Pulsed Plasma Thruster Circuits

    Science.gov (United States)

    Toftul, Alexandra; Polzin, Kurt A.; Hudgins, Jerry L.

    2014-01-01

    Inductive Pulsed Plasma Thruster (IPPT) pulse circuits, such as those needed to operate the Pulsed Inductive Thruster (PIT), are required to quickly switch capacitor banks operating at a period of µs while conducting current at levels on the order of at least 10 kA. [1,2] For all iterations of the PIT to date, spark gaps have been used to discharge the capacitor bank through an inductive coil. Recent availability of fast, high-power solid state switching devices makes it possible to consider the use of semiconductor switches in modern IPPTs. In addition, novel pre-ionization schemes have led to a reduction in discharge energy per pulse for electric thrusters of this type, relaxing the switching requirements for these thrusters. [3,4] Solid state switches offer the advantage of greater controllability and reliability, as well as decreased drive circuit dimensions and mass relative to spark gap switches. The use of solid state devices such as Integrated Gate Bipolar Transistors (IGBTs), Gate Turn-off Thyristors (GTOs) and Silicon-Controlled Rectifiers (SCRs) often involves the use of power diodes. These semiconductor devices may be connected antiparallel to the switch for protection from reverse current, or used to reduce power loss in a circuit by clamping off current ringing. In each case, higher circuit efficiency may be achieved by using a diode that is able to transition, or 'switch,' from the forward conducting state ('on' state) to the reverse blocking state ('off' state) in the shortest amount of time, thereby minimizing current ringing and switching losses. Silicon Carbide (SiC) PiN diodes offer significant advantages to conventional fast-switching Silicon (Si) diodes for high power and fast switching applications. A wider band gap results in a breakdown voltage 10 times that of Si, so that a SiC device may have a thinner drift region for a given blocking voltage. [5] This leads to smaller, lighter devices for high voltage applications, as well as reduced

  17. Energy Saving in Three-Phase Diode Rectifiers Using EI Technique with Adjustable Switching Frequency Scheme

    DEFF Research Database (Denmark)

    Davari, Pooya; Zare, Firuz; Yang, Yongheng

    2016-01-01

    A front-end rectifier can significantly impact a power electronics system performance and efficiency for applications such as motor drive where the system commonly operates under partial loading conditions. This paper proposes an adjustable switching frequency scheme using an electronic inductor...

  18. Graphene Based Reversible Nano-Switch/Sensor Schottky Diode (NANOSSSD) Device

    Science.gov (United States)

    Miranda, Felix A. (Inventor); Theofylaktos, Onoufrios (Inventor); Pinto, Nicholas J. (Inventor); Mueller, Carl H. (Inventor); Santos, Javier (Inventor); Meador, Michael A. (Inventor)

    2015-01-01

    A nanostructure device is provided and performs dual functions as a nano-switching/sensing device. The nanostructure device includes a doped semiconducting substrate, an insulating layer disposed on the doped semiconducting substrate, an electrode formed on the insulating layer, and at least one layer of graphene formed on the electrode. The at least one layer of graphene provides an electrical connection between the electrode and the substrate and is the electroactive element in the device.

  19. Efficient high-energy pulse generation from a diode-side-pumped passively Q-switched Nd:YAG laser and application for optical parametric oscillator

    International Nuclear Information System (INIS)

    Huang, Y P; Huang, Y J; Cho, C Y

    2014-01-01

    We employ a convex–concave resonator to develop a high-pulse-energy diode-side-pumped passively Q-switched Nd:YAG laser with high extraction efficiency. At a diode pump energy of 227 mJ, the output laser pulse reaches 30 mJ with a pulse width of 6 ns at a repetition rate of 20 Hz. The optical-to-optical conversion efficiency is up to 13.2%. Based on the developed Nd:YAG laser oscillator, we further employ a monolithic KTP crystal to perform the optical parametric oscillator (OPO). With the 1064 nm input energy of 30 mJ, the OPO energy at 1573 nm is found to be 13.3 mJ, corresponding to an OPO conversion efficiency as high as 44.3%. (letters)

  20. Self-organization of the Q-switched mode-locked regime in a diode-pumped Nd:YAG laser

    Science.gov (United States)

    Donin, V. I.; Yakovin, D. V.; Gribanov, A. V.

    2015-06-01

    A new Q-switched mode-locked generation regime of a solid-state laser, in which a Q-switch is "spontaneously" formed at the frequency of relaxation oscillations, has been observed for the first time. The new generation has been implemented by means of the previously proposed method of an acoustic modulator of a traveling wave in combination with a spherical mirror of a cavity. Stable pulse trains with a repetition frequency of ~30 kHz and a duration of ~2 µs have been observed in the diode-pump Nd:YAG laser with an average output power of ~3 W. Each train contains about 200 equispaced single pulses with a duration of ~45 ps.

  1. Performance enhancement of sub-nanosecond diode-pumped passively Q-switched Yb:YAG microchip laser with diamond surface cooling.

    Science.gov (United States)

    Zhuang, W Z; Chen, Yi-Fan; Su, K W; Huang, K F; Chen, Y F

    2012-09-24

    We experimentally confirm that diamond surface cooling can significantly enhance the output performance of a sub-nanosecond diode-end-pumped passively Q-switched Yb:YAG laser. It is found that the pulse energy obtained with diamond cooling is approximately 1.5 times greater than that obtained without diamond cooling, where a Cr(4+):YAG absorber with the initial transmission of 84% is employed. Furthermore, the standard deviation of the pulse amplitude peak-to-peak fluctuation is found to be approximately 3 times lower than that measured without diamond cooling. Under a pump power of 3.9 W, the passively Q-switched Yb:YAG laser can generate a pulse train of 3.3 kHz repetition rate with a pulse energy of 287 μJ and with a pulse width of 650 ps.

  2. A fast 8-channel wavelength switching DFB diode laser array based on reconstruction-equivalent-chirp technique

    Science.gov (United States)

    Li, Wei; Wang, Yingying; Du, Yinchao; Du, Weikang; Zhao, Guowang; Fang, Tao

    2018-01-01

    We propose a new method to investigate fast wavelength switching, which consists of control circuit, driving circuit and 8-channel DFB laser array using reconstruction-equivalent-chirp technique. The control circuit is in charge of selecting required lasers to switch wavelength, the driving circuit supply adjustable and stable direct current to the DFB laser arrays. Experimental results show that wavelength switching time of 8 channels is about 500ns and stability of laser output is promised.

  3. Effects of uneven temperature of IGBT and diode on switching characteristics of bridge legs in MW-level power converters

    DEFF Research Database (Denmark)

    Luo, Haoze; Iannuzzo, Francesco; Blaabjerg, Frede

    2016-01-01

    This paper proposes an independent temperature test method for switching characteristic evaluation of high-power single switch modules. For high-power bridge legs, the commutation occurs between two discrete IGBT modules. To simulate the junction differences between two modules caused by mission ...

  4. Dual-wavelength mid-infrared CW and Q-switched laser in diode end-pumped Tm,Ho:GdYTaO4 crystal

    Science.gov (United States)

    Wang, Beibei; Gao, Congcong; Dou, Renqin; Nie, Hongkun; Sun, Guihua; Liu, Wenpeng; Yu, Haijuan; Wang, Guoju; Zhang, Qingli; Lin, Xuechun; He, Jingliang; Wang, Wenjun; Zhang, Bingyuan

    2018-02-01

    Dual-wavelength continuous-wave and Q-switched lasers are demonstrated in a Tm,Ho:GdYTaO4 crystal under 790 nm laser diode end pumping for the first time to the best of our knowledge. The laser operates with a dual wavelength at 1949.677 nm and 2070 nm for continuous-wave with a spacing of about 120 nm. The maximum output power is 0.332 W with a pump power of 3 W. By using graphene as the saturable absorber, a passively Q-switched operation is performed with a dual-wavelength at 1950.323 nm and 2068.064 nm with a wavelength interval of about 118 nm. The maximum average output power of the Q-switched laser goes up to 200 mW with a minimum pulse duration of 1.2 µs and a maximum repetition rate of 34.72 kHz.

  5. Efficient in-band diode-pumped Q-switched solid state laser for methane detection, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop an efficient, tunable Q-switched SSL operating at a wavelength of 1651 nm with pulse energy >1 mJ at 2000 Hz repetition rate with in-band...

  6. Resistive switching mechanism in the one diode-one resistor memory based on p+-Si/n-ZnO heterostructure revealed by in-situ TEM.

    Science.gov (United States)

    Zhang, Lei; Zhu, Liang; Li, Xiaomei; Xu, Zhi; Wang, Wenlong; Bai, Xuedong

    2017-03-21

    One diode-one resistor (1D1R) memory is an effective architecture to suppress the crosstalk interference, realizing the crossbar network integration of resistive random access memory (RRAM). Herein, we designed a p + -Si/n-ZnO heterostructure with 1D1R function. Compared with the conventional multilayer 1D1R devices, the structure and fabrication technique can be largely simplified. The real-time imaging of formation/rupture process of conductive filament (CF) process demonstrated the RS mechanism by in-situ transmission electron microscopy (TEM). Meanwhile, we observed that the formed CF is only confined to the outside of depletion region of Si/ZnO pn junction, and the formation of CF does not degrade the diode performance, which allows the coexistence of RS and rectifying behaviors, revealing the 1D1R switching model. Furthermore, it has been confirmed that the CF is consisting of the oxygen vacancy by in-situ TEM characterization.

  7. The impact of etched trenches geometry and dielectric material on the electrical behaviour of silicon-on-insulator self-switching diodes

    Energy Technology Data Exchange (ETDEWEB)

    Farhi, G; Charlebois, S A [Departement de genie electrique et genie informatique, et Institut interdisciplinaire d' innovation technologique (3IT), Universite de Sherbrooke, 2500, Boulevard de l' Universite, J1K 2R1, Sherbrooke, QC (Canada); Morris, D [Departement de physique et Institut interdisciplinaire d' innovation technologique (3IT), Universite de Sherbrooke, 2500, Boulevard de l' Universite, J1K 2R1, Sherbrooke, QC (Canada); Raskin, J-P, E-mail: ghania.farhi@usherbrooke.ca [Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Universite catholique de Louvain, Place du Levant, 3, B-1348 Louvain-la-Neuve (Belgium)

    2011-10-28

    Hole electrical transport in a p-doped nanochannel defined between two L-shape etched trenches made on a silicon-on-insulator substrate is investigated using a TCAD-Medici simulator. We study the impact of the etched trenches' geometry and dielectric filling materials on the current-voltage characteristics of the device. Carrier accumulation on frontiers defined by the trenches causes a modulation of the hole density inside the conduction channel as the bias voltage varies and this gives rise to a diode-like characteristic. For a 1.2 {mu}m-long channel, plots of the electric field distribution show that a nonlinear transport regime is reached at a moderate reverse and forward bias of {+-} 2 V. Plots of the carrier velocity along the conduction channel show that holes remain hot for a few hundreds of nm outside the nanometre-wide channel, at a bias of {+-} 10 V. Filling the etched trenches with a high-{kappa} dielectric material gives rise to a lower threshold voltage, V{sub th}. A similar decrease of V{sub th} is also achieved by reducing the longitudinal and/or the transverse trench width. Our simulation results provide useful design guidelines for future integrated self-switching-diode-based circuits.

  8. Improvement of stability and efficiency in diode-pumped passively Q-switched intracavity optical parametric oscillator with a monolithic cavity

    International Nuclear Information System (INIS)

    Huang, J Y; Zhuang, W Z; Huang, Y P; Huang, Y J; Su, K W; Chen, Y F

    2012-01-01

    We improve the performance of intracavity optical parametric oscillator (IOPO) pumped by a diode-pumped Q-switched Nd:YVO 4 /Cr 4+ :YAG laser. The IOPO cavity is formed independently by a monolithic KTP crystal that the mirrors are directly deposited on top of the nonlinear crystal. We study the performances of this IOPO cavity with different reflectivity of the output coupler at 1.5 μm (R s ) of 80 and 50%. The average power of 1.5 μm is up to 3.3 W at the maximum pump power of 16.8 W for both cases. The diode-to-signal conversion efficiency is up to 20%, which is the highest one for IOPOs to our best knowledge. At the maximum pump power, the pulse energies are 41 μJ with the pulse width of 3 ns at a pulse repetition rate (PRR) of 80 kHz for R s = 80% and 51 μJ with the pulse width of 1.2 ns at a PRR of 65 kHz for R s = 50%, respectively. The pulse amplitude fluctuations in standard deviation are 2.6% for R s = 80% and 4% for R s = 50%, respectively

  9. Resistive switching mechanism in the one diode-one resistor memory based on p+-Si/n-ZnO heterostructure revealed by in-situ TEM

    Science.gov (United States)

    Zhang, Lei; Zhu, Liang; Li, Xiaomei; Xu, Zhi; Wang, Wenlong; Bai, Xuedong

    2017-03-01

    One diode-one resistor (1D1R) memory is an effective architecture to suppress the crosstalk interference, realizing the crossbar network integration of resistive random access memory (RRAM). Herein, we designed a p+-Si/n-ZnO heterostructure with 1D1R function. Compared with the conventional multilayer 1D1R devices, the structure and fabrication technique can be largely simplified. The real-time imaging of formation/rupture process of conductive filament (CF) process demonstrated the RS mechanism by in-situ transmission electron microscopy (TEM). Meanwhile, we observed that the formed CF is only confined to the outside of depletion region of Si/ZnO pn junction, and the formation of CF does not degrade the diode performance, which allows the coexistence of RS and rectifying behaviors, revealing the 1D1R switching model. Furthermore, it has been confirmed that the CF is consisting of the oxygen vacancy by in-situ TEM characterization.

  10. Q-Switched and Mode Locked Short Pulses from a Diode Pumped, YB-Doped Fiber Laser

    Science.gov (United States)

    2009-03-26

    polarization maintaining (PM) at a length of 8.7 ± 0.1 m. The surface area of the PANDA -style fiber is pictured in figure 3.3 (a) [46]. The core diameter was...diode- pumped c-cut Nd:GdVO4 laser,” Optics Communications 231 (2004) pg 365-369. 36. W. G. Wagner, B. A. Lengyel, "Evolution of the giant pulse in a

  11. CW and Q-switched performance of a diode end-pumped Yb:YAG laser. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Bibeau, C.; Beach, R.; Ebbers, C.; Emanuel, M.; Skidmore, J.

    1997-02-19

    Using an end-pumped technology developed at LLNL we have demonstrated a Yb:YAG laser capable of delivering up to 434 W of CW power and 226 W of Q-switched power. In addition, we have frequency doubled the output to 515 nm using a dual crystal scheme to produce 76 W at 10 kHz in a 30 ns pulse length.

  12. Permittivity and temperature effects on rectification performance of self-switching diodes with different geometrical structures using two-dimensional device simulator

    Science.gov (United States)

    Zakaria, N. F.; Kasjoo, S. R.; Zailan, Z.; Isa, M. M.; Taking, S.; Arshad, M. K. M.

    2017-12-01

    Characterization on an InGaAs-based self-switching diode (SSD) using technology computer aided design (TCAD) aimed for optimizing the electrical rectification performance of the device is reported. The rectifying performance is mainly contributed by a parameter known as the curvature coefficient which is derived from the current-voltage (I-V) behavior of the device. As such, the curvature coefficient of SSD was analyzed in this work, not only by varying the device's geometrical structure, but also by implementing different dielectric relative permittivity of the device's trenches, ranging from 1.0 to 10. Furthermore, the simulations were performed under temperature range of 300-600 K. The results showed that increased temperature degraded the SSD's rectifying performance due to increased reverse current which can deteriorate the nonlinearity of the device's I-V characteristic. Moreover, an improved curvature coefficient can be achieved using silicon dioxide (∼3.9) as the SSD trenches. The cut-off frequency of SSD with zero-bias curvature coefficient of ∼30 V-1 attained in this work was approximately 80 GHz, operating at unbiased condition. The results obtained can assist the design of SSD to efficiently operate as rectifiers at microwave and terahertz frequencies.

  13. Performance of continuous wave and acousto-optically Q-switched Tm, Ho: YAP laser pumped by diode laser

    Science.gov (United States)

    Li, Guoxing; Xie, Wenqiang; Yang, Xining; Zhang, Ziqiu; Zhang, Hongda; Zhang, Liang

    2018-02-01

    A two-end-pumped a-cut Tm(0.5%), Ho(0.5%):YAP laser output at 2119nm is reported under cryogenic temperature. The maximum output power reached to 7.76W with the incident pump power of 24.2W in CW mode. With the acousto-optically Q-switch, an average power of 7.3W can be obtained, when the pulse repetition frequency was 7.5 kHz. The corresponding optical-to-optical conversion efficiency was 30.2% and the slope efficiency was 31.4%. Then, the laser output characteristics in the repetition frequency of 7.5 kHz and 10kHz were researched. The output power, the optical-to-optical conversion efficiency and slope efficiency were increased with the increase of the repetition frequency. In the same repetition frequency, the pulse duration was decreasing with the growth of the incident pump power.

  14. A high-peak-power UV picosecond-pulse light source based on a gain-switched 1.55 microm laser diode and its application to time-resolved spectroscopy of blue-violet materials.

    Science.gov (United States)

    Sato, Aya; Kono, Shunsuke; Saito, Kyosuke; Sato, Ki-ichi; Yokoyama, Hiroyuki

    2010-02-01

    We generated sub-kilowatt peak-power and 6-ps duration 390-nm optical pulses via the fourth harmonic generation of amplified optical output from a gain-switched 1.55-microm laser diode. We obtained a power-conversion-efficiency of 12% from 1.55-microm to 390-nm light, and subsequently applied the ultraviolet pulses to time-resolved spectroscopy of blue-violet luminescent materials, including a Coumarine dye solution and nitride semiconductor materials using single-photon and two-photon excitation schemes.

  15. Combination of Q-switched and quasi long-pulsed 1064-nm Nd:YAG laser, non-ablative 1450-nm diode laser, and ablative 10 600-nm carbon dioxide fractional laser for enlarged pores.

    Science.gov (United States)

    Cho, Sung Bin; Noh, Seongmin; Lee, Sang Ju; Kang, Jin Moon; Kim, Young Koo; Lee, Ju Hee

    2010-07-01

    Currently, there is no gold standard for the treatment of enlarged facial pores. In this report, we describe a patient with enlarged nasal pores which were treated with a combination of a non-ablative 1450-nm diode laser, a Q-switched and quasi long-pulsed 1064-nm Nd:YAG laser, and an ablative 10 600-nm carbon dioxide fractional laser system. Four months after the final treatment, the condition of the patient's pores had markedly improved, and the patient was satisfied with the results.

  16. Comparison of high-power diode pumped actively Q-switched double-clad flower shape co-doped-Er3+:Yb3+fiber laser using acousto-optic and mechanical (optical) modulators

    Science.gov (United States)

    El-Sherif, Ashraf F.; Harfosh, Amr

    2015-09-01

    A diode-pumped acousto-optic Q-switching Er3+:Yb3+ co-doped high-power fiber laser is reported, laser output average power in excess of 1.65 W was achieved for Q-switching at relatively high repetition rates from 10 to 100 kHz. The shortest pulse duration obtained was 10 ns, giving a highest peak power of 9.8 kW and 98 μJ energy per pulse, this is the highest power yet reported from any type of actively Q-switched flower double-clad Er3+:Yb3+ fiber laser operating in low order mode at 1550 nm. The pulse train with high pulse-to-pulse stability of 95% occurred at a range of repetition rates up to 100 kHz with peak power of 0.4 kW, 40 ns pulse width and 16 μJ energy per pulse at 1550 nm for a launched pump power of 5 W. With the mechanical modulation Q-switching of the Er3+:Yb3+ co-doped fiber laser, it was found that the narrowest pulse width of 35 ns was obtained with peak power of 15.5 kW and energy per pulse 0.5 mJ at pulse repetition frequency of 1 kHz. A moderate pulse-to-pulse stability of 75% occurred over a range of high repetition rates. A comparison between mechanical modulation and acousto-optic Q-switching has been made at a repetition rate of 20 kHz. The energy per pulse, pulse width, and the average power of a mechanical optical Q-switching laser were greater than for the acousto-optic Q-switching, but the pulse width is narrower and so the high peak power of an acousto-optic Q-switching pulse is greater than for the mechanical (optical) Q-switching laser at repetition rates of up to 100 kHz.

  17. Mathematical solutions of rate equations of a laser-diode end-pumped passively Q-switched and mode locked Nd-laser with Cr4+:YAG polarized saturable absorber

    International Nuclear Information System (INIS)

    Abdul Ghani, B.; Hammadi, M.

    2012-01-01

    The intracavity frequency-doubling (IFD) of a simultaneous passively Q-switched mode-locked diode-pumped Nd 3 + - laser is studied with a polarized isotropic Cr 4 +: YAG saturable absorber. A general recurrence formula for the mode-locked pulses under the Q-switched envelope at fundamental wavelength has been reconstructed in order to analyze the temporal shape behavior of a single Q-switched envelope with mode-locking pulse trains. This formula has been derived taking into account the impact of the IFD and polarized Cr 4 +: YAG saturable absorber.The presented mathematical model describes the self-induced anisotropy appeared in the polarized Cr 4 +: YAG in the nonlinear stage of the giant pulse formation. For the anisotropic Nd 3 +: YVO 4 active medium, the generated polarized waves are assumed to be fixed through the lasing cycle. Besides, the maximum absorber initial transmission and the minimum mirror reflectivity values have been determined from the second threshold criterion. The calculated numerical results demonstrate the impact of the variation of the input laser parameters (rotational angle of the polarized crystal, absorber initial transmission and the output mirror reflectivity) on the characteristics of the output laser pulse (SH peak power, pulse width, pulse duration and shift pulse position of central mode). The calculated numerical results in this work is in good qualitative and quantitative agreement with the available experimental data reported in the references. (author)

  18. Diode laser pumping

    International Nuclear Information System (INIS)

    Skagerlund, L.E.

    1975-01-01

    A diode laser is pumped or pulsed by a repeated capacitive discharge. A capacitor is periodically charged from a dc voltage source via a transformer, the capacitor being discharged through the diode laser via a controlled switching means after one or more charging periods. During a first interval of each charging period the transformer, while unloaded, stores a specific amount of energy supplied from the dc voltage source. During a subsequent interval of the charging period said specific amount of energy is transmitted from the transformer to the capacitor. The discharging of the capacitor takes place during a first interval of a charging period. (auth)

  19. Comparison of the leading-edge timing walk in pulsed TOF laser range finding with avalanche bipolar junction transistor (BJT) and metal-oxide-semiconductor (MOS) switch based laser diode drivers.

    Science.gov (United States)

    Hintikka, Mikko; Hallman, Lauri; Kostamovaara, Juha

    2017-12-01

    Timing walk error in pulsed time-of-flight based laser range finding was studied using two different types of laser diode drivers. The study compares avalanche bipolar junction transistor (BJT) and metal-oxide-semiconductor field-effect transistor switch based laser pulse drivers, both producing 1.35 ns current pulse length (full width at half maximum), and investigates how the slowly rising part of the current pulse of the avalanche BJT based driver affects the leading edge timing walk. The walk error was measured to be very similar with both drivers within an input signal dynamic range of 1:10 000 (receiver bandwidth of 700 MHz) but increased rapidly with the avalanche BJT based driver at higher values of dynamic range. The slowly rising part does not exist in the current pulse produced by the metal-oxide-semiconductor (MOS) based laser driver, and thus the MOS based driver can be utilized in a wider dynamic range.

  20. 16.7 W 885 nm diode-side-pumped actively Q-switched Nd:YAG/YVO4 intracavity Raman laser at 1176 nm

    Science.gov (United States)

    Jiang, Pengbo; Zhang, Guizhong; Liu, Jian; Ding, Xin; Sheng, Quan; Yu, Xuanyi; Sun, Bing; Shi, Rui; Wu, Liang; Wang, Rui; Yao, Jianquan

    2017-11-01

    We proposed and experimentally demonstrated the generation of high-power 1176 nm Stokes wave by frequency shifting of a 885 nm diode-side-pumped Nd:YAG laser using a YVO4 crystal in a Z-shaped cavity configuration. Employing the 885 nm diode-side-pumped scheme and the Z-shaped cavity, for the first time to our knowledge, we realized the thermal management effectively, achieving excellent 1176 nm Stokes wave consequently. With an incident pump power of ~190.0 W, a maximum average output power of 16.7 W was obtained at the pulse repetition frequency of 10 kHz. The pulse duration and spectrum linewidth of the Stokes wave at the maximum output power were 20.3 ns and ~0.08 nm, respectively.

  1. Avalanche mode of high-voltage overloaded p{sup +}–i–n{sup +} diode switching to the conductive state by pulsed illumination

    Energy Technology Data Exchange (ETDEWEB)

    Kyuregyan, A. S., E-mail: ask@vei.ru [Lenin All-Russia Electrical Engineering Institute (Russian Federation)

    2015-07-15

    A simple analytical theory of the picosecond switching of high-voltage overloaded p{sup +}–i–n{sup +} photodiodes to the conductive state by pulsed illumination is presented. The relations between the parameters of structure, light pulse, external circuit, and main process characteristics, i.e., the amplitude of the active load current pulse, delay time, and switching duration, are derived and confirmed by numerical simulation. It is shown that the picosecond light pulse energy required for efficient switching can be decreased by 6–7 orders of magnitude due to the intense avalanche multiplication of electrons and holes. This offers the possibility of using pulsed semiconductor lasers as a control element of optron pairs.

  2. Avalanche mode of high-voltage overloaded p+–i–n+ diode switching to the conductive state by pulsed illumination

    International Nuclear Information System (INIS)

    Kyuregyan, A. S.

    2015-01-01

    A simple analytical theory of the picosecond switching of high-voltage overloaded p + –i–n + photodiodes to the conductive state by pulsed illumination is presented. The relations between the parameters of structure, light pulse, external circuit, and main process characteristics, i.e., the amplitude of the active load current pulse, delay time, and switching duration, are derived and confirmed by numerical simulation. It is shown that the picosecond light pulse energy required for efficient switching can be decreased by 6–7 orders of magnitude due to the intense avalanche multiplication of electrons and holes. This offers the possibility of using pulsed semiconductor lasers as a control element of optron pairs

  3. Plasma erosion switch

    International Nuclear Information System (INIS)

    Mendel, C.W. Jr.; Goldstein, S.A.; Miller, P.A.

    1976-01-01

    The plasma erosion switch is a device capable of initially carrying high currents, and then of opening in nanoseconds to stand off high voltages. It depends upon the erosion of a plasma which initially fills the switch. The sheath between the plasma and the cathode behaves as a diode with a rapidly increasing A-K gap. Preliminary tests of the switch on the Proto I accelerator at Sandia will be described. In these tests, the switch consisted of a cylinder of highly ionized plasma four inches in diameter and one-inch thick surrounding a one-inch cathode. The switch shorted out prepulse voltages and allowed energy to be stored in the diode inductance outside the switch until the accelerator current reached 75 kA. The switch impedance then rose rapidly to approximately 100 ω in 5 nanoseconds, whereupon the accelerator current transferred to the cathode. Current rise rates of 3.10 13 A/sec were limited by cathode turn-on. Voltage rise rates of 10 15 V/sec were achieved. The elimination of prepulse and machine turn-on transients allowed A-K gaps of 2 mm to be used with 2.5 MV pulses, yielding average E fields of 12 MV/cm. Staged versions of the device are being built and should improve rise rates. The switch shows promise for use with future, higher power, lower inductance machines

  4. Regulating Charge and Exciton Distribution in High-Performance Hybrid White Organic Light-Emitting Diodes with n-Type Interlayer Switch

    Science.gov (United States)

    Luo, Dongxiang; Yang, Yanfeng; Xiao, Ye; Zhao, Yu; Yang, Yibin; Liu, Baiquan

    2017-10-01

    The interlayer (IL) plays a vital role in hybrid white organic light-emitting diodes (WOLEDs); however, only a negligible amount of attention has been given to n-type ILs. Herein, the n-type IL, for the first time, has been demonstrated to achieve a high efficiency, high color rendering index (CRI), and low voltage trade-off. The device exhibits a maximum total efficiency of 41.5 lm W-1, the highest among hybrid WOLEDs with n-type ILs. In addition, high CRIs (80-88) at practical luminances (≥1000 cd m-2) have been obtained, satisfying the demand for indoor lighting. Remarkably, a CRI of 88 is the highest among hybrid WOLEDs. Moreover, the device exhibits low voltages, with a turn-on voltage of only 2.5 V (>1 cd m-2), which is the lowest among hybrid WOLEDs. The intrinsic working mechanism of the device has also been explored; in particular, the role of n-type ILs in regulating the distribution of charges and excitons has been unveiled. The findings demonstrate that the introduction of n-type ILs is effective in developing high-performance hybrid WOLEDs. [Figure not available: see fulltext.

  5. Semiconductor laser diodes and the design of a D.C. powered laser diode drive unit

    OpenAIRE

    Cappuccio, Joseph C., Jr.

    1988-01-01

    Approved for public release; distribution is unlimited This thesis addresses the design, development and operational analysis of a D.C. powered semiconductor laser diode drive unit. A laser diode requires an extremely stable power supply since a picosecond spike of current or power supply switching transient could result in permanent damage. The design offers stability and various features for operational protection of the laser diode. The ability to intensity modulate (analog) and pulse m...

  6. Radiation-sensitive switching circuits

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.H.; Cockshott, C.P.

    1976-03-16

    A radiation-sensitive switching circuit includes a light emitting diode which from time to time illuminates a photo-transistor, the photo-transistor serving when its output reaches a predetermined value to operate a trigger circuit. In order to allow for aging of the components, the current flow through the diode is increased when the output from the transistor falls below a known level. Conveniently, this is achieved by having a transistor in parallel with the diode, and turning the transistor off when the output from the phototransistor becomes too low. The circuit is designed to control the ignition system in an automobile engine.

  7. Modelling switching power converters as complementarity systems

    NARCIS (Netherlands)

    Camlibel, Mehmet; Iannelli, Luigi; Vasca, Francesco

    2004-01-01

    Switched complementarity models of linear circuits with ideal diodes and/or ideal switches allow one to study well-posedness and stability issues for these circuits by employing the complementarity problems of the mathematical programming. In this paper, we demonstrate that other types of typical

  8. Terahertz optoelectronics with surface plasmon polariton diode.

    Science.gov (United States)

    Vinnakota, Raj K; Genov, Dentcho A

    2014-05-09

    The field of plasmonics has experience a renaissance in recent years by providing a large variety of new physical effects and applications. Surface plasmon polaritons, i.e. the collective electron oscillations at the interface of a metal/semiconductor and a dielectric, may bridge the gap between electronic and photonic devices, provided a fast switching mechanism is identified. Here, we demonstrate a surface plasmon-polariton diode (SPPD) an optoelectronic switch that can operate at exceedingly large signal modulation rates. The SPPD uses heavily doped p-n junction where surface plasmon polaritons propagate at the interface between n and p-type GaAs and can be switched by an external voltage. The devices can operate at transmission modulation higher than 98% and depending on the doping and applied voltage can achieve switching rates of up to 1 THz. The proposed switch is compatible with the current semiconductor fabrication techniques and could lead to nanoscale semiconductor-based optoelectronics.

  9. A SOFT SWITCHED INTERLEAVED HIGH GAIN DC-DC CONVERTER

    Directory of Open Access Journals (Sweden)

    SHESHIDHAR REDDY ADDULA

    2017-09-01

    Full Text Available In this paper, a novel soft-switched interleaved DC-DC converter which provides a high voltage gain of 12 is proposed. Voltage gain of the basic interleaved boost converter is extended by using diode-capacitor multiplier (DCM cells. The switches are operated at a nominal duty ratio of 0.5. The voltage stress on the power switches and diodes is only a fraction of the output voltage. To enhance the operating power conversion efficiency, the switches are turned ON at zero voltage condition. Experimental results of 18-216V, 100W prototype converter validate the operating principle and the advantageous features of the presented converter.

  10. Heat switch technology for cryogenic thermal management

    Science.gov (United States)

    Shu, Q. S.; Demko, J. A.; E Fesmire, J.

    2017-12-01

    Systematic review is given of development of novel heat switches at cryogenic temperatures that alternatively provide high thermal connection or ideal thermal isolation to the cold mass. These cryogenic heat switches are widely applied in a variety of unique superconducting systems and critical space applications. The following types of heat switch devices are discussed: 1) magnetic levitation suspension, 2) shape memory alloys, 3) differential thermal expansion, 4) helium or hydrogen gap-gap, 5) superconducting, 6) piezoelectric, 7) cryogenic diode, 8) magneto-resistive, and 9) mechanical demountable connections. Advantages and limitations of different cryogenic heat switches are examined along with the outlook for future thermal management solutions in materials and cryogenic designs.

  11. Diode-pumped Er3+:Yb3+:NaCe0.43Gd0.57(WO4)2 pulse laser passively Q -switched with a Co2+:Mg0.4Al2.4O4 saturable absorber at 1.53 μ m

    International Nuclear Information System (INIS)

    Chen, Y J; Huang, J H; Lin, Y F; Luo, Z D; Huang, Y D; Zou, Y Q

    2014-01-01

    Based on the long fluorescence lifetime of upper laser level 4 I 13/2 of Er 3+ ions and high 1.5−1.6 μm laser operation efficiency, an Er 3+ :Y b 3+ :NaCe 0.43 Gd 0.57 (WO 4 ) 2 crystal was used to generate a Q-switched pulse laser with high energy and low threshold. End-pumped by a 970 nm diode laser, a passively Q-switched 1.5−1.6 μm pulse laser was first realized in an Er 3+ and Y b 3+ co-doped tungstate crystal, when a Co 2+ :Mg 0.4 Al 2.4 O 4 spinel crystal was used as saturable absorber. A 1.53 μm pulse laser with about 22 μJ energy, 76 ns duration and 21 kHz repetition rate was obtained at an absorbed pump power of 12 W in a c-cut 1.7-mm-thick Er 3+ :Y b 3+ :NaCe 0.43 Gd 0.57 (WO 4 ) 2 crystal. (paper)

  12. Graphene Q-switched Yb:KYW planar waveguide laser

    NARCIS (Netherlands)

    Kim, Jun Wan; Choi, Sun Young; Aravazhi, S.; Pollnau, Markus; Griebner, Uwe; Petrov, Valentin; Bae, Sukang; Ahn, Kwang Jun; Yeom, Dong-Il; Rotermund, Fabian

    A diode-pumped Yb:KYW planar waveguide laser, single-mode Q-switched by evanescent-field interaction with graphene, is demonstrated for the first time. Few-layer graphene grown by chemical vapor deposition is transferred onto the top of a guiding layer, which initiates stable Q-switched operation in

  13. DC switching regulated power supply for driving an inductive load

    Science.gov (United States)

    Dyer, George R.

    1986-01-01

    A power supply for driving an inductive load current from a dc power supply hrough a regulator circuit including a bridge arrangement of diodes and switching transistors controlled by a servo controller which regulates switching in response to the load current to maintain a selected load current. First and second opposite legs of the bridge are formed by first and second parallel-connected transistor arrays, respectively, while the third and fourth legs of the bridge are formed by appropriately connected first and second parallel connected diode arrays, respectively. The regulator may be operated in three "stages" or modes: (1) For current runup in the load, both first and second transistor switch arrays are turned "on" and current is supplied to the load through both transistor arrays. (2) When load current reaches the desired level, the first switch is turned "off", and load current "flywheels" through the second switch array and the fourth leg diode array connecting the second switch array in series with the load. Current is maintained by alternating between modes 1 and 2 at a suitable duty cycle and switching rate set by the controller. (3) Rapid current rundown is accomplished by turning both switch arrays "off", allowing load current to be dumped back into the source through the third and fourth diode arrays connecting the source in series opposition with the load to recover energy from the inductive load. The three operating states are controlled automatically by the controller.

  14. High-Voltage Switch Containing (DI)2 Devices

    Science.gov (United States)

    Hanes, Maurice H.; Fiedor, Richard J.

    1987-01-01

    Series switching diodes triggered on by passing above threshold voltage. High-voltage switch made by connecting multitude of deep-impurity, double-injection devices in series with each other and with another, triggerable high-voltage device such as thyristor. Device operates near ground potential to avoid insulation problems in triggering circuit.

  15. Pseudospark switches

    International Nuclear Information System (INIS)

    Billault, P.; Riege, H.; Gulik, M. van; Boggasch, E.; Frank, K.

    1987-01-01

    The pseudospark discharge is bound to a geometrical structure which is particularly well suited for switching high currents and voltages at high power levels. This type of discharge offers the potential for improvement in essentially all areas of switching operation: peak current and current density, current rise, stand-off voltage, reverse current capability, cathode life, and forward drop. The first pseudospark switch was built at CERN at 1981. Since then, the basic switching characteristics of pseudospark chambers have been studied in detail. The main feature of a pseudospark switch is the confinement of the discharge plasma to the device axis. The current transition to the hollow electrodes is spread over a rather large surface area. Another essential feature is the easy and precise triggering of the pseudospark switch from the interior of the hollow electrodes, relatively far from the main discharge gap. Nanosecond delay and jitter values can be achieved with trigger energies of less than 0.1 mJ, although cathode heating is not required. Pseudospark gaps may cover a wide range of high-voltage, high-current, and high-pulse-power switching at repetition rates of many kilohertz. This report reviews the basic researh on pseudospark switches which has been going on at CERN. So far, applications have been developed in the range of thyratron-like medium-power switches at typically 20 to 40 kV and 0.5 to 10 kA. High-current pseudospark switches have been built for a high-power 20 kJ pulse generator which is being used for long-term tests of plasma lenses developed for the future CERN Antiproton Collector (ACOL). The high-current switches have operated for several hundred thousand shots, with 20 to 50 ns jitter at 16 kV charging voltage and more than 100 kA peak current amplitude. (orig.)

  16. 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...

  17. Diode and Diode Circuits, a Programmed Text.

    Science.gov (United States)

    Balabanian, Norman; Kirwin, Gerald J.

    This programed text on diode and diode circuits was developed under contract with the United States Office of Education as Number 4 in a series of materials for use in an electrical engineering sequence. It is intended as a supplement to a regular text and other instructional material. (DH)

  18. Microprocessor Controlled Capacitor Bank Switching System for ...

    African Journals Online (AJOL)

    In this work, analysis and development of a microprocessor controlled capacitor bank switching system for deployment in a smart distribution network was carried out. This system was implemented by the use of discreet components such as resistors, capacitors, transistor, diode, automatic voltage regulator, with the ...

  19. Switching antidepressants

    African Journals Online (AJOL)

    depressive disorder, with response rates of 50-60%. Switching within or between classes of antidepressants is often required in patients with an insufficient response to SSRIs.12 Because they share a similar mechanism of action, the immediate substitution of one SSRI for another is probably the easiest switching option.

  20. Molecular Rotors as Switches

    Directory of Open Access Journals (Sweden)

    Kang L. Wang

    2012-08-01

    Full Text Available The use of a functional molecular unit acting as a state variable provides an attractive alternative for the next generations of nanoscale electronics. It may help overcome the limits of conventional MOSFETd due to their potential scalability, low-cost, low variability, and highly integratable characteristics as well as the capability to exploit bottom-up self-assembly processes. This bottom-up construction and the operation of nanoscale machines/devices, in which the molecular motion can be controlled to perform functions, have been studied for their functionalities. Being triggered by external stimuli such as light, electricity or chemical reagents, these devices have shown various functions including those of diodes, rectifiers, memories, resonant tunnel junctions and single settable molecular switches that can be electronically configured for logic gates. Molecule-specific electronic switching has also been reported for several of these device structures, including nanopores containing oligo(phenylene ethynylene monolayers, and planar junctions incorporating rotaxane and catenane monolayers for the construction and operation of complex molecular machines. A specific electrically driven surface mounted molecular rotor is described in detail in this review. The rotor is comprised of a monolayer of redox-active ligated copper compounds sandwiched between a gold electrode and a highly-doped P+ Si. This electrically driven sandwich-type monolayer molecular rotor device showed an on/off ratio of approximately 104, a read window of about 2.5 V, and a retention time of greater than 104 s. The rotation speed of this type of molecular rotor has been reported to be in the picosecond timescale, which provides a potential of high switching speed applications. Current-voltage spectroscopy (I-V revealed a temperature-dependent negative differential resistance (NDR associated with the device. The analysis of the device

  1. A new Zero-Voltage-Transition PWM switching cell

    Energy Technology Data Exchange (ETDEWEB)

    Grigore, V. [Electronics and Telecommunications Faculty `Politebuica` University Bucharest (Romania); Kyyrae, J. [Helsinki University of Technology, Otaniemi (Finland): Institute of Intelligent Power Electronics

    1997-12-31

    In this paper a new Zero-Voltage-Transition (ZVT) PWM switching cell is presented. The proposed switching cell is composed of the normal hard-switched PWM cell (consisting of one active switch and one passive switch), plus an auxiliary circuit (consisting of one active switch and some reactive components). The auxiliary circuit is inactive during the ON and OFF intervals of the switches in the normal PWM switch. However, the transitions between the two states are controlled by the auxiliary circuit. Prior to turn-on, the voltage across the active switch in the PWM cell is forced to zero, thus the turn-on losses of the active switch are practically eliminated. At turn-off the auxiliary circuit behaves like a non-dissipative passive snubber reducing the turn-off losses to a great extent. Zero-Voltage-Transition switching technique almost eliminates switching losses. The active switch operates under ZVT conditions, the passive switch (diode) has a controlled reverse recovery, and the switch in the auxiliary circuit operates under Zero-Current-Switching (ZCS) conditions. (orig.) 6 refs.

  2. Magnetic switching

    International Nuclear Information System (INIS)

    Kirbie, H.C.

    1989-01-01

    Magnetic switching is a pulse compression technique that uses a saturable inductor (reactor) to pass pulses of energy between two capacitors. A high degree of pulse compression can be achieved in a network when several of these simple, magnetically switched circuits are connected in series. Individual inductors are designed to saturate in cascade as a pulse moves along the network. The technique is particularly useful when a single-pulse network must be very reliable or when a multi-pulse network must operate at a high pulse repetition frequency (PRF). Today, magnetic switches trigger spark gaps, sharpen the risetimes of high energy pulses, power large lasers, and drive high PRF linear induction accelerators. This paper will describe the technique of magnetic pulse compression using simple networks and design equations. A brief review of modern magnetic materials and of their role in magnetic switch design will be presented. 12 refs., 8 figs

  3. Switched-capacitor isolated LED driver

    Science.gov (United States)

    Sanders, Seth R.; Kline, Mitchell

    2016-03-22

    A switched-capacitor voltage converter which is particularly well-suited for receiving a line voltage from which to drive current through a series of light emitting diodes (LEDs). Input voltage is rectified in a multi-level rectifier network having switched capacitors in an ascending-bank configuration for passing voltages in uniform steps between zero volts up to full received voltage V.sub.DC. A regulator section, operating on V.sub.DC, comprises switched-capacitor stages of H-bridge switching and flying capacitors. A current controlled oscillator drives the states of the switched-capacitor stages and changes its frequency to maintain a constant current to the load. Embodiments are described for isolating the load from the mains, utilizing an LC tank circuit or a multi-primary-winding transformer.

  4. A NOVEL SINGLE IMPEDANCE NETWORK BASED NEUTRAL POINT CLAMPED SEVEN LEVEL THREE PHASE INVETER WITH REDUCED CLAMPING DIODES FOR REGENERATIVE APPLICATIONS

    OpenAIRE

    T. A. Raghavendiran; C.L.Kuppuswamy

    2012-01-01

    A Multilevel Inverter (MLI) can eliminate the need for the step-up transformer and reduce the harmonics produced by the inverter. This paper presents Neutral Point Clamped (NPC) seven level inverter with less number of clamping diodes which is suitable for regenerative loads such as three phase induction motor with regenerative braking. To reduce the stress across the main switches, diodes are clamped anti-parallel to the main switches. In Earlier configurations, the numbers of clamping diode...

  5. Coaxial foilless diode

    International Nuclear Information System (INIS)

    Kong, Long; Liu, QingXiang; Li, XiangQiang; Wang, ShaoMeng

    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 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

  6. Buck Converter with Soft-Switching Cells for PV Panel Applications

    Directory of Open Access Journals (Sweden)

    Cheng-Tao Tsai

    2016-03-01

    Full Text Available In power conversion of photovoltaic (PV energy, a hard-switching buck converter always generates some disadvantages. For example, serious electromagnetic interference (EMI, high switching losses, and stresses on an active switch (metal-oxide-semiconductor-field-effect-transistor, MOSFET, and high reverse-recovery losses of a freewheeling diode result in low conversion efficiency. To release these disadvantages, a buck converter with soft-switching cells for PV panel applications is proposed. To create zero-voltage-switching (ZVS features of the active switches, a simple active soft-switching cell with an inductor, a capacitor, and a MOSFET is incorporated into the proposed buck converter. Therefore, the switching losses and stresses of the active switches and EMI can be reduced significantly. To reduce reverse-recovery losses of a freewheeling diode, a simple passive soft-switching cell with a capacitor and two diodes is implemented. To verify the performance and the feasibility of the proposed buck converter with soft-switching cells for PV panel applications, a prototype soft-switching buck converter is built and implemented by using a maximum-power-point-tracking (MPPT method. Simulated and experimental results are presented from a 100 W soft-switching buck converter for PV panel applications.

  7. A Broadband Ultrathin Nonlinear Switching Metamaterial

    Directory of Open Access Journals (Sweden)

    E. Zarnousheh Farahani

    2017-05-01

    Full Text Available In this paper, an ultrathin planar nonlinear metamaterial slab is designed and simulated. Nonlinearity is provided through placing diodes in each metamaterial unit cell. The diodes are auto-biased and activated by an incident wave. The proposed structure represents a broadband switching property between two transmission and reflection states depending on the intensity of the incident wave. High permittivity values are presented creating a near zero effective impedance at low power states, around the second resonant mode of the structure unit cell; as the result, the incident wave is reflected. Increasing the incident power to the level which can activate the loaded diodes in the structure results in elimination of the resonance and consequently a drop in the permittivity values near the permeability one as well as a switch to the transmission state. A full wave as well as a nonlinear simulations are performed. An optimization method based on weed colonization is applied to the unit cell of the metamaterial slab to achieve the maximum switching bandwidth. The structure represents a 24% switching bandwidth of a 10 dB reduction in the reflection coefficient.

  8. Radiation-sensitive switching circuits

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.H.; Cockshott, C.P.

    1976-03-16

    A radiation-sensitive switching circuit has a light emitting diode which supplies light to a photo-transistor, the light being interrupted from time to time. When the photo-transistor is illuminated, current builds up and when this current reaches a predetermined value, a trigger circuit changes state. The peak output of the photo-transistor is measured and the trigger circuit is arranged to change state when the output of the device is a set proportion of the peak output, so as to allow for aging of the components. The circuit is designed to control the ignition system in an automobile engine.

  9. A new Zero-Current-Transition PWM switching cell

    Energy Technology Data Exchange (ETDEWEB)

    Grigore, V. [Electronics and Telecommunications Faculty, `Politechnica` University Bucharest (Romania); Kyyrae, J. [Helsinki University of Technology, Otaniemi (Finland): Institute of Intelligent Power Electronics

    1997-12-31

    In this paper a new Zero-Current-Transition (ZCT) PWM switching cell is presented. The proposed switching cell is composed of the normal hard-switched PWM cell (consisting of one active switch and one passive switch), plus as auxiliary circuit. The auxiliary circuit is inactive during the ON ad OFF intervals of the switches in the normal PWM switch. The transitions between the two states are controlled by the auxiliary circuit. Prior to turn-off, the current through the active switch in the PWM cell is forced to zero, thus the turn-off losses of the active switch are practically eliminated. At turn-on the auxiliary circuit slows down the growing rate of the current through the main switch. Thus, turn-on losses are also very much reduced. The active switch operates under ZCT conditions, the passive switch (diode) has a controlled reverse recovery, while the switch in the auxiliary circuit operates under Zero-Current-Switching (ZCS) conditions. (orig.) 3 refs.

  10. Fast-opening vacuum switches for high-power inductive energy storage

    International Nuclear Information System (INIS)

    Cooperstein, G.

    1988-01-01

    The subject of fast-opening vacuum switches for high-power inductive energy storage is emerging as an exciting new area of plasma science research. This opening switch technology, which generally involves the use of plasmas as the switching medium, is key to the development of inductive energy storage techniques for pulsed power which have a number of advantages over conventional capacitive techniques with regard to cost and size. This paper reviews the state of the art in this area with emphasis on applications to inductive storage pulsed power generators. Discussion focuses on fast-opening vacuum switches capable of operating at high power (≥10 12 W). These include plasma erosion opening switches, ion beam opening switches, plasma filled diodes, reflex diodes, plasma flow switches, and other novel vacuum opening switches

  11. Vortex diode jet

    Science.gov (United States)

    Houck, Edward D.

    1994-01-01

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  12. Granular acoustic switches and logic elements

    Science.gov (United States)

    Li, Feng; Anzel, Paul; Yang, Jinkyu; Kevrekidis, Panayotis G.; Daraio, Chiara

    2014-10-01

    Electrical flow control devices are fundamental components in electrical appliances and computers; similarly, optical switches are essential in a number of communication, computation and quantum information-processing applications. An acoustic counterpart would use an acoustic (mechanical) signal to control the mechanical energy flow through a solid material. Although earlier research has demonstrated acoustic diodes or circulators, no acoustic switches with wide operational frequency ranges and controllability have been realized. Here we propose and demonstrate an acoustic switch based on a driven chain of spherical particles with a nonlinear contact force. We experimentally and numerically verify that this switching mechanism stems from a combination of nonlinearity and bandgap effects. We also realize the OR and AND acoustic logic elements by exploiting the nonlinear dynamical effects of the granular chain. We anticipate these results to enable the creation of novel acoustic devices for the control of mechanical energy flow in high-performance ultrasonic devices.

  13. 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.

  14. Photoconductive switch enhancements for use in Blumlein pulse generators

    International Nuclear Information System (INIS)

    Davanloo, F.; Park, H.; Collins, C. B.; Agee, F. J.

    1999-01-01

    Stacked Blumlein pulse generators developed at the University of Texas at Dallas have produced high-power waveforms with risetimes and repetition rates in the range of 0.2-50 ns and 1-300 Hz, respectively, using a conventional thyratron, spark gap or photoconductive switch. Adaptation of the design has enabled the stacked Blumleins to produce 80 MW, nanosecond pulses with risetimes better than 200 ps into nominally matched loads. The device has a compact line geometry and is commutated by a single GaAs photoconductive switch triggered by a low power laser diode array. Our current investigations involve the switch characteristics that affect the broadening of the current channels in the avalanche, pre-avalanche seedings, the switch lifetime and the durability. This report presents the progress toward improving the GaAs switch operation and lifetime in stacked Blumlein pulsers. Advanced switch treatments including diamond film overcoating are implemented and discussed

  15. Accurate diode behavioral model with reverse recovery

    Science.gov (United States)

    Banáš, Stanislav; Divín, Jan; Dobeš, Josef; Paňko, Václav

    2018-01-01

    This paper deals with the comprehensive behavioral model of p-n junction diode containing reverse recovery effect, applicable to all standard SPICE simulators supporting Verilog-A language. The model has been successfully used in several production designs, which require its full complexity, robustness and set of tuning parameters comparable with standard compact SPICE diode model. The model is like standard compact model scalable with area and temperature and can be used as a stand-alone diode or as a part of more complex device macro-model, e.g. LDMOS, JFET, bipolar transistor. The paper briefly presents the state of the art followed by the chapter describing the model development and achieved solutions. During precise model verification some of them were found non-robust or poorly converging and replaced by more robust solutions, demonstrated in the paper. The measurement results of different technologies and different devices compared with a simulation using the new behavioral model are presented as the model validation. The comparison of model validation in time and frequency domains demonstrates that the implemented reverse recovery effect with correctly extracted parameters improves the model simulation results not only in switching from ON to OFF state, which is often published, but also its impedance/admittance frequency dependency in GHz range. Finally the model parameter extraction and the comparison with SPICE compact models containing reverse recovery effect is presented.

  16. Low-cost photoacoustic imaging systems based on laser diode and light-emitting diode excitation

    Directory of Open Access Journals (Sweden)

    Qingkai Yao

    2017-07-01

    Full Text Available Photoacoustic imaging, an emerging biomedical imaging modality, holds great promise for preclinical and clinical researches. It combines the high optical contrast and high ultrasound resolution by converting laser excitation into ultrasonic emission. In order to generate photoacoustic signal efficiently, bulky Q-switched solid-state laser systems are most commonly used as excitation sources and hence limit its commercialization. As an alternative, the miniaturized semiconductor laser system has the advantages of being inexpensive, compact, and robust, which makes a significant effect on production-forming design. It is also desirable to obtain a wavelength in a wide range from visible to near-infrared spectrum for multispectral applications. Focussing on practical aspect, this paper reviews the state-of-the-art developments of low-cost photoacoustic system with laser diode and light-emitting diode excitation source and highlights a few representative installations in the past decade.

  17. All-Optical flip-flop operation using a SOA and DFB laser diode optical feedback combination

    DEFF Research Database (Denmark)

    D'Oosterlinck, W.; Öhman, Filip; Buron, Jakob Due

    2007-01-01

    We report on the switching of an all-optical flip-flop consisting of a semiconductor optical amplifier (SOA) and a distributed feedback laser diode (DFB), bidirectionally coupled to each other. Both simulation and experimental results are presented. Switching times as low as 50ps, minimal required...

  18. Simple, compact, and low cost CO2 laser driven by fast high voltage solid state switch for industrial application

    Science.gov (United States)

    Tanaka, Miyu; Tei, Masaya; Uno, Kazuyuki; Nakano, Hitoshi

    2017-02-01

    A longitudinally excited CO2 laser driven with a reverse recovery characteristics of high voltage diode has been developed. A diode is used to control the high voltage pulse as an opening switch. Power supply for longitudinally excited CO2 laser is composed of a pulse generator, transformer, capacitor, and a diode, is very simple. Laser oscillation has been successfully achieved, several tens of mJ in laser energy has been obtained.

  19. Dual wavelength operation in diode-end-pumped hybrid vanadate ...

    Indian Academy of Sciences (India)

    Dual wavelength operation at 1062.8 nm and 1064.1 nm in a diode-pumped hybrid laser comprising of Nd3+-doped birefringent YVO4 and GdVO4 crystals is demon-strated. A detailed characterization of the laser is performed under CW and pulsed operation. Under Q-switching, 4 W of average power at 5 kHz repetition ...

  20. Switched on!

    CERN Multimedia

    2008-01-01

    Like a star arriving on stage, impatiently followed by each member of CERN personnel and by millions of eyes around the world, the first beam of protons has circulated in the LHC. After years in the making and months of increasing anticipation, today the work of hundreds of people has borne fruit. WELL DONE to all! Successfully steered around the 27 kilometres of the world’s most powerful particle accelerator at 10:28 this morning, this first beam of protons circulating in the ring marks a key moment in the transition from over two decades of preparation to a new era of scientific discovery. "It’s a fantastic moment," said the LHC project leader Lyn Evans, "we can now look forward to a new era of understanding about the origins and evolution of the universe". Starting up a major new particle accelerator takes much more than flipping a switch. Thousands of individual elements have to work in harmony, timings have to be synchronize...

  1. Study of opening switch characteristics of a plasma focus

    International Nuclear Information System (INIS)

    Rhee, M.J.; Schneider, R.F.

    1985-01-01

    It is shown that a current charged transmission line and an opening switch can be used as an inductive energy storage system to produce a high power pulse. A plasma focus device, in which a transmission line is inserted in series with the capacitor bank and a coaxial gun, is considered as an inductive energy storage system. The m = 0 instability in the plasma focus is utilized as an opening switch and the disrupted plasma column is considered as bipolar diode. The system is described preferably by the transmission line theory rather than the lumped circuit theory. The relationship between the output voltage and the current drop is given by V = ΔIZ, where Z is the characteristic impedance of the transmission line. The current drop ΔI depends on the mismatched load impenance of the plasma diode which is governed by nature of the m = 0 instability. Experimental investigation of opening switch behavior of the m = 0 instability is described

  2. Comparison of laser diode response to pulsed electrical and radiative excitations

    International Nuclear Information System (INIS)

    Baggio, J.; Rainsant, J.M.; D'hose, C.; Lalande, P.; Musseau, O.; Leray, J.L.

    1996-01-01

    The authors have studied the electrical and optical response of two laser diodes under transient irradiation. Both diodes exhibit a positive photocurrent, which adds to the bias current, and a decrease of the optical power until extinction when dose rate is increased. Direct carrier generation in the laser cavity is a second order phenomena. The diode overall response is driven by both the substrate photocurrent and the transient conduction of current confinement regions, which decrease the net current density in the cavity and switches-off the laser emission. This behavior is in good agreement with pulsed electrical characterizations and 2D simulations

  3. Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

    Science.gov (United States)

    Maeda, Y

    1994-01-10

    Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

  4. Deep diode atomic battery

    International Nuclear Information System (INIS)

    Anthony, T.R.; Cline, H.E.

    1977-01-01

    A deep diode atomic battery is made from a bulk semiconductor crystal containing three-dimensional arrays of columnar and lamellar P-N junctions. The battery is powered by gamma rays and x-ray emission from a radioactive source embedded in the interior of the semiconductor crystal

  5. Infrared diode laser spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Civiš, Svatopluk; Cihelka, Jaroslav; Matulková, Irena

    2010-01-01

    Roč. 18, č. 4 (2010), s. 408-420 ISSN 1230-3402 R&D Projects: GA AV ČR IAA400400705 Institutional research plan: CEZ:AV0Z40400503 Keywords : FTIR spectroscopy * absorption spectroscopy * laser diodes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.027, year: 2010

  6. Design considerations for high-power VHF radar transceivers: T/R switch design

    Science.gov (United States)

    Ecklund, W. L.

    1983-01-01

    The transceiver (TR) switch developed at NOAA's Aeronomy Laboratory for use in their 50 kW peak power, 50 MHz transmitter is described. The switch mounts inside the transmitter chassis and was designed to be compact while retaining the ability to handle well over 50 kW peak power at average power levels up to 2 kW. The TR switch is a conventional TR/ATR design with equivalent /4 transmission line sections constructed of lumped constant coils and transmitting capacitors in ''Tee' sections. Two TR sections are placed in series to achieve adequate receiver protection. The switch is set into the ''transmit' mode by forward biasing the 3 pin diodes to about 1.2 amperes each. The receive mode is achieved by back biasing the diodes to -15 volts. A directional coupler is also incorporated into the TR switch box to provide a convenient monitor point for forward and reflected transmitter power.

  7. A modified two-level three-phase quasi-soft-switching inverter

    DEFF Research Database (Denmark)

    Liu, Yusheng; Wu, Weimin; Blaabjerg, Frede

    2014-01-01

    A traditional Voltage Source Inverter (VSI) has higher efficiency than a Current Voltage Source (CSI) due to the less conduction power loss. However, the reverse recovery of the free-wheeling diode limits the efficiency improvement for the silicon devices based hard-switching VSI. The traditional...... quasi-soft-switching inverter can alternate between VSI and CSI by using a proper control scheme and thereby reduce the power losses caused by the reverse recovery of the free-wheeling diode. Nevertheless, slightly extra conduction power loss of the auxiliary switch is also introduced. In order...... to reduce the extra conduction power loss and the voltage stress across the DC-link capacitor, a modified two-level three-phase quasi-soft-switching inverter is proposed by using a SiC MOSFET instead of an IGBT. The principle of the modified two-level three-phase quasi-soft-switching inverter is analyzed...

  8. Testing of Diode-Clamping in an Inductive Pulsed Plasma Thruster Circuit

    Science.gov (United States)

    Toftul, Alexandra; Polzin, Kurt A.; Martin, Adam K.; Hudgins, Jerry L.

    2014-01-01

    Testing of a 5.5 kV silicon (Si) diode and 5.8 kV prototype silicon carbide (SiC) diode in an inductive pulsed plasma thruster (IPPT) circuit was performed to obtain a comparison of the resulting circuit recapture efficiency,eta(sub r), defined as the percentage of the initial charge energy remaining on the capacitor bank after the diode interrupts the current. The diode was placed in a pulsed circuit in series with a silicon controlled rectifier (SCR) switch, and the voltages across different components and current waveforms were collected over a range of capacitor charge voltages. Reverse recovery parameters, including turn-off time and peak reverse recovery current, were measured and capacitor voltage waveforms were used to determine the recapture efficiency for each case. The Si fast recovery diode in the circuit was shown to yield a recapture efficiency of up to 20% for the conditions tested, while the SiC diode further increased recapture efficiency to nearly 30%. The data presented show that fast recovery diodes operate on a timescale that permits them to clamp the discharge quickly after the first half cycle, supporting the idea that diode-clamping in IPPT circuit reduces energy dissipation that occurs after the first half cycle

  9. 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

  10. Crossbar memory array of organic bistable rectifying diodes for nonvolatile data storage

    NARCIS (Netherlands)

    Asadi, Kamal; Li, Mengyuan; Stingelin, Natalie; Blom, Paul W. M.; de Leeuw, Dago M.

    2010-01-01

    Cross-talk in memories using resistive switches in a cross-bar geometry can be prevented by integration of a rectifying diode. We present a functional cross bar memory array using a phase separated blend of a ferroelectric and a semiconducting polymer as storage medium. Each intersection acts

  11. 101 W of average green beam from diode-side-pumped Nd:YAG ...

    Indian Academy of Sciences (India)

    switched. Nd:YAG rod laser using 18 mm long type-II phase-matched LBO crystal in a relay-imaged cavity is reported. A single pump head comprised of Nd:YAG rod, diffusive reflectors and linear array laser diode bars is used. 101 W of average green ...

  12. A soft switching with reduced voltage stress ZVT-PWM full-bridge converter

    Science.gov (United States)

    Sahin, Yakup; Ting, Naim Suleyman; Acar, Fatih

    2018-04-01

    This paper introduces a novel active snubber cell for soft switching pulse width modulation DC-DC converters. In the proposed converter, the main switch is turned on under zero voltage transition and turned off under zero voltage switching (ZVS). The auxiliary switch is turned on under zero current switching (ZCS) and turned off under zero current transition. The main diode is turned on under ZVS and turned off under ZCS. All of the other semiconductors in the converter are turned on and off with soft switching. There is no extra voltage stress on the semiconductor devices. Besides, the proposed converter has simple structure and ease of control due to common ground. The detailed theoretical analysis of the proposed converter is presented and also verified with both simulation and experimental study at 100 kHz switching frequency and 600 W output power. Furthermore, the efficiency of the proposed converter is 95.7% at nominal power.

  13. Controller Architectures for Switching

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2009-01-01

    This paper investigate different controller architectures in connection with controller switching. The controller switching is derived by using the Youla-Jabr-Bongiorno-Kucera (YJBK) parameterization. A number of different architectures for the implementation of the YJBK parameterization...... are described and applied in connection with controller switching. An architecture that does not include inversion of the coprime factors is introduced. This architecture will make controller switching particular simple....

  14. Isolated and soft-switched power converter

    Science.gov (United States)

    Peng, Fang Zheng; Adams, Donald Joe

    2002-01-01

    An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

  15. The Impacts of Platinum Diffusion to the Reverse Recovery Lifetime of a High Power Diode Devices

    Directory of Open Access Journals (Sweden)

    Cheh C.M.

    2016-01-01

    Full Text Available The reverse recovery lifetime of a diode is one the key parameter in power electronics market. To make a diode with fast switching speed, diodes are often doped with impurities such as gold and platinum to improve its lifetime. In this works, we present the reverse recovery lifetime improvement of a power rectifier diode through platinum diffusion in the intrinsic region in between P-N junction using Design of Experiment (DOE approach. A commercial available power rectifier is used in this study. We factored in the temperature and thermal diffusion time during the platinum diffusion process in our DOE. From results, DOE 2 (with shorter thermal duration and high temperature for diffusion is selected based on meeting requirement for forward voltage and reverse recovery specifications i.e. forward voltage at 1.8V and reverse recovery time at 27ns.

  16. Air-stable memory array of bistable rectifying diodes based on ferroelectric-semiconductor polymer blends

    Science.gov (United States)

    Kumar, Manasvi; Sharifi Dehsari, Hamed; Anwar, Saleem; Asadi, Kamal

    2018-03-01

    Organic bistable diodes based on phase-separated blends of ferroelectric and semiconducting polymers have emerged as promising candidates for non-volatile information storage for low-cost solution processable electronics. One of the bottlenecks impeding upscaling is stability and reliable operation of the array in air. Here, we present a memory array fabricated with an air-stable amine-based semiconducting polymer. Memory diode fabrication and full electrical characterizations were carried out in atmospheric conditions (23 °C and 45% relative humidity). The memory diodes showed on/off ratios greater than 100 and further exhibited robust and stable performance upon continuous write-read-erase-read cycles. Moreover, we demonstrate a 4-bit memory array that is free from cross-talk with a shelf-life of several months. Demonstration of the stability and reliable air operation further strengthens the feasibility of the resistance switching in ferroelectric memory diodes for low-cost applications.

  17. Diode-pumped neodymium lasers

    Science.gov (United States)

    Albers, Peter

    1990-08-01

    Since the invention of diode lasers in the early 1960's there had been continuous investigations in laser diode pumped solid state lasers as has been reviewed in detail by a number of papers ( see e.g. [1] ). There are two main advantages of using diode lasers instead of flashlaraps as a pump source for solid state lasers: First the emission of the diode lasers matches well with the absorption bands of several Rare Earth ions that are doped in laser crystals ( mainly Nd3+, but also Er3, Tm3, Dy3', and others ) . This summary will report only about diode lasers at a wavelength of around BlOnm, which fits to an absorptionband of Nd3t Second diode lasers provide the possibility of longitudinally pumped configurations and therefore an excellent mode matching with the solid state laser mode. For both reasons the efficiency of a diode laser puniped solid state laser is nuch higher than of a flashlamp pumped one. Since the early 1980's a much wider interest in diode laser pumped solid state lasers arose. It was stimulated by the improved performance of the new generation of diode lasers in terms of reliability , operational lifetime and output power [21. Two important steps in direction to the diode lasers at present time were the developments of double hetero (DH) structure- and graded index separate confinement hetero (GrInSCH) structurediode lasers. In the same way the development of new production techniques were necessary to ensure the reliability of the diode lasers. Starting with the liquid phase epitaxy (LPE) the (GaAl)As structures are now grown by the molecular beam epitaxy (MBE), mainly used for very high precision laboratory investigations, and metal organic chemical vapour deposition (MOCVD), mainly used for commercial production. As a first commercial product SDL introduced a 100mW array in 1984. Since then the output power of the commercially available diode lasers increased by two orders of magnitude to lOW. These diode lasers are multi stripe bar arrays

  18. Optical diagnosis system for intense electron beam diode plasma

    International Nuclear Information System (INIS)

    Yang Jie; Shu Ting; Zhang Jun; Fan Yuwei; Yang Jianhua; Liu Lie; Yin Yi; Luo Ling

    2012-01-01

    A nanosecond time-resolved imaging platform for diode plasmas diagnostics has been constructed based on the pulsed electron beam accelerator and high speed framing camera (HSFC). The accelerator can provide an electrical pulse with voltages of 200-500 kV, rise-time (from 10% to 90% amplitude) of 25 ns and duration of 110 ns. The diode currents up to kA level can be extracted. The trigger signal for camera was picked up by a water-resistor voltage divider after the main switch of the accelerator, which could avoid the disadvantageous influence of the time jitter caused by the breakdown of the gas gaps. Then the sampled negative electrical pulse was converted into a transistor-transistor logic (TTL) signal (5 V) with rise time of about 1.5 ns and time jitter less than 1 ns via a processor. And this signal was taken as the synchronization time base. According to the working characteristics of the camera, the synchronization scheme relying mainly on electrical pulse delay method supplemented by light signal delay method was determined to make sure that the camera can work synchronously with the light production and transportation from the diode plasma within the time scale of nanosecond. Moreover, shielding and filtering methods were used to restrain the interference on the measurement system from the accelerator. Finally, time resolved 2-D framing images of the diode plasma were acquired. (authors)

  19. Design of a high power laser diode driver

    Science.gov (United States)

    Li, Wen-jiang; Wang, Qian-qian; Liu, Li; Peng, Zhong

    2013-12-01

    Laser diodes are preferred light sources for compact non-scanning imaging laser radar systems due to their small volume and easiness to be integrated. Therefore, lots of present studies focus on research of modulation characteristics of highpower laser diodes. A high-frequency modulated driver for a compact non-scanning imaging laser radar system is described in this paper. It is based on linear constant current theory and can modulate a high power laser diode quasi-continuously. A high-speed operational amplifier is used to drive a power MOSFET, which can take full advantages of the power MOSFET-low driver current and good dynamic characteristics. In addition, an operational amplifier and PI (Proportion-Integration) control are applied in a negative feedback network to improve the current stability further. In order to avoid damaging the laser diode, a slow start circuit and over-current protection circuit have also been designed. The maximum current of the over-current protection circuit can be set according to the requirement. In addition, the power supply can also be switched between CW and QCW operating modes. When the high power semiconductor laser is modulated by large signal, some nonlinear effects will occur such as turn-on delay, relaxation oscillation and modulation chirp. Some theoretical analysis and experimental research on some nonlinear effects have also been done. Experimental results are consistent with theoretical analysis by using this driver for a 1W GaAs quantum well laser.

  20. Study of opening switch characteristics of a plasma focus

    International Nuclear Information System (INIS)

    Rhee, M.J.; Schneider, R.F.

    1985-01-01

    It is shown that a current charged transmission line and an opening switch can be used as an inductive energy storage system to produce a high power pulse. A plasma focus device, in which a transmission line is inserted in series with the capacitor bank and a coaxial gun, is considered as an inductive energy storage system. The m = 0 instability in the plasma focus is utilized as an opening switch and the disrupted plasma column is considered as bipolar diode. The system is described preferably by the transmission line theory rather than the lumped circuit theory. The relationship between the output voltage and the current drop is given by V = ΔIZ, where Z is the characteristic impedance of the transmission line. The current drop ΔI depends on the mismatched load impedance of the plasma diode which is governed by nature of the m = 0 instability

  1. Polymer light emitting diodes

    International Nuclear Information System (INIS)

    Gautier-Thianche, Emmmanuelle

    1998-01-01

    We study sandwich type semiconducting polymer light emitting diodes; anode/polymer/cathode. ITO is selected as anode, this polymer is a blend of a commercially available polymer with a high hole transport ability: polyvinyl-carbazole and a laser dye: coumarin-515. Magnesium covered with silver is chosen for the anode. We study the influence of polymer thickness and coumarin doping ratio on electroluminescence spectrum, electric characteristics and quantum efficiency. An important drawback is that diodes lifetime remains low. In the second part of our study we determine degradations causes with X-Ray reflectivity experiments. It may be due to ITO very high roughness. We realize a new type of planar electroluminescent device: a channel type electroluminescent device in which polymer layer is inserted into an aluminium channel. Such a device is by far more stable than using classical sandwich structures with the same polymer composition: indeed, charges are generated by internal-field ionization and there is no injection from the electrode to the polymer. This avoids electrochemical reactions at electrodes, thus reducing degradations routes. (author) [fr

  2. Light Emitting Diode (LED)

    Science.gov (United States)

    1997-01-01

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

  3. Biosensing with Nanofluidic Diodes

    Science.gov (United States)

    Vlassiouk, Ivan; Kozel, Thomas R.; Siwy, Zuzanna S.

    2014-01-01

    Recently reported nanofluidic diodes with highly nonlinear current-voltage characteristics offer a unique possibility to construct different biosensors. These sensors are based on local changes of the surface charge on walls of single conical nanopores induced by binding of an analyte. The analyte binding can be detected as a change of the ion current rectification of single nanopores defined as a ratio of currents for voltages of one polarity, and currents for voltages of the opposite polarity. In this Article we provided both modeling and experimental studies of various biosensing routes based on monitoring changes of the rectification degree in nanofluidic diodes used as a biosensing platform. A prototype of a sensor for the capsular poly γ-D-glutamic acid (γDPGA) from Bacillus anthracis is presented. The nanopore used for the sensing was locally modified with the monoclonal antibody for γDPGA. The proof of principle of the rectification degree based sensing was further shown by preparation of sensors for avidin and streptavidin. Our devices also allowed for determination of isoelectric point of the minute amounts of proteins immobilized on the surface. PMID:19507907

  4. 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.

  5. Fast all-optical flip-flop based on a single distributed feedback laser diode.

    Science.gov (United States)

    Huybrechts, Koen; Morthier, Geert; Baets, Roel

    2008-07-21

    Since there is an increasing demand for fast networks and switches, the electronic data processing imposes a severe bottleneck and all-optical processing techniques will be required in the future. All-optical flip-flops are one of the key components because they can act as temporary memory elements. Several designs have already been demonstrated but they are often relatively slow or complex to fabricate. We demonstrate experimentally fast flip-flop operation in a single DFB laser diode which is one of the standard elements in today's telecommunication industry. Injecting continuous wave light in the laser diode, a bistability is obtained due to the spatial hole burning effect. We can switch between the two states by using pulses with energies below 200 fJ resulting in flip-flop operation with switching times below 75 ps and repetition rates of up to 2 GHz.

  6. Nanowire resonant tunneling diodes

    Science.gov (United States)

    Björk, M. T.; Ohlsson, B. J.; Thelander, C.; Persson, A. I.; Deppert, K.; Wallenberg, L. R.; Samuelson, L.

    2002-12-01

    Semiconductor heterostructures and their implementation into electronic and photonic devices have had tremendous impact on science and technology. In the development of quantum nanoelectronics, one-dimensional (1D) heterostructure devices are receiving a lot of interest. We report here functional 1D resonant tunneling diodes obtained via bottom-up assembly of designed segments of different semiconductor materials in III/V nanowires. The emitter, collector, and the central quantum dot are made from InAs and the barrier material from InP. Ideal resonant tunneling behavior, with peak-to-valley ratios of up to 50:1 and current densities of 1 nA/μm2 was observed at low temperatures.

  7. Emitron: microwave diode

    Science.gov (United States)

    Craig, G.D.; Pettibone, J.S.; Drobot, A.T.

    1982-05-06

    The invention comprises a new class of device, driven by electron or other charged particle flow, for producing coherent microwaves by utilizing the interaction of electromagnetic waves with electron flow in diodes not requiring an external magnetic field. Anode and cathode surfaces are electrically charged with respect to one another by electron flow, for example caused by a Marx bank voltage source or by other charged particle flow, for example by a high energy charged particle beam. This produces an electric field which stimulates an emitted electron beam to flow in the anode-cathode region. The emitted electrons are accelerated by the electric field and coherent microwaves are produced by the three dimensional spatial and temporal interaction of the accelerated electrons with geometrically allowed microwave modes which results in the bunching of the electrons and the pumping of at least one dominant microwave mode.

  8. Atomic spectroscopy with diode lasers

    International Nuclear Information System (INIS)

    Tino, G.M.

    1994-01-01

    Some applications of semiconductor diode lasers in atomic spectroscopy are discussed by describing different experiments performed with lasers emitting in the visible and in the near-infrared region. I illustrate the results obtained in the investigation of near-infrared transitions of atomic oxygen and of the visible intercombination line of strontium. I also describe how two offset-frequency-locked diode lasers can be used to excite velocity selective Raman transitions in Cs. I discuss the spectral resolution, the accuracy of frequency measurements, and the detection sensitivity achievable with diode lasers. (orig.)

  9. Laterally injected light-emitting diode and laser diode

    Science.gov (United States)

    Miller, Mary A.; Crawford, Mary H.; Allerman, Andrew A.

    2015-06-16

    A p-type superlattice is used to laterally inject holes into an III-nitride multiple quantum well active layer, enabling efficient light extraction from the active area. Laterally-injected light-emitting diodes and laser diodes can enable brighter, more efficient devices that impact a wide range of wavelengths and applications. For UV wavelengths, applications include fluorescence-based biological sensing, epoxy curing, and water purification. For visible devices, applications include solid state lighting and projection systems.

  10. High breakdown voltage Au/Pt/GaN Schottky diodes

    International Nuclear Information System (INIS)

    Dang, G. T.; Zhang, A. P.; Mshewa, M. M.; Ren, F.; Chyi, J.-I.; Lee, C.-M.; Chuo, C. C.; Chi, G. C.; Han, J.; Chu, S. N. G.

    2000-01-01

    Au/Pt/GaN Schottky diode rectifiers were fabricated with reverse breakdown voltage (V RB ) up to 550 V on vertically depleting structures and >2000 V on lateral devices. The figure-of-merit (V RB ) 2 /R ON , where R ON is the on-state resistance, had values between 4.2 and 4.8 MW cm -2 . The reverse leakage currents and forward on-voltages were still somewhat higher than the theoretical minimum values, but were comparable to SiC Schottky rectifiers reported in the literature. These devices show promise for use in ultrahigh-power switches. (c) 2000 American Vacuum Society

  11. Saturated Switching Systems

    CERN Document Server

    Benzaouia, Abdellah

    2012-01-01

    Saturated Switching Systems treats the problem of actuator saturation, inherent in all dynamical systems by using two approaches: positive invariance in which the controller is designed to work within a region of non-saturating linear behaviour; and saturation technique which allows saturation but guarantees asymptotic stability. The results obtained are extended from the linear systems in which they were first developed to switching systems with uncertainties, 2D switching systems, switching systems with Markovian jumping and switching systems of the Takagi-Sugeno type. The text represents a thoroughly referenced distillation of results obtained in this field during the last decade. The selected tool for analysis and design of stabilizing controllers is based on multiple Lyapunov functions and linear matrix inequalities. All the results are illustrated with numerical examples and figures many of them being modelled using MATLAB®. Saturated Switching Systems will be of interest to academic researchers in con...

  12. Effective switching frequency multiplier inverter

    Science.gov (United States)

    Su, Gui-Jia; Peng, Fang Z.

    2007-08-07

    A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

  13. FreeSWITCH Cookbook

    CERN Document Server

    Minessale, Anthony

    2012-01-01

    This is a problem-solution approach to take your FreeSWITCH skills to the next level, where everything is explained in a practical way. If you are a system administrator, hobbyist, or someone who uses FreeSWITCH on a regular basis, this book is for you. Whether you are a FreeSWITCH expert or just getting started, this book will take your skills to the next level.

  14. Enhanced vbasis laser diode package

    Science.gov (United States)

    Deri, Robert J.; Chen, Diana; Bayramian, Andy; Freitas, Barry; Kotovsky, Jack

    2014-08-19

    A substrate having an upper surface and a lower surface is provided. The substrate includes a plurality of v-grooves formed in the upper surface. Each v-groove includes a first side and a second side perpendicular to the first side. A laser diode bar assembly is disposed within each of the v-grooves and attached to the first side. The laser diode bar assembly includes a first adhesion layer disposed on the first side of the v-groove, a metal plate attached to the first adhesion layer, a second adhesion layer disposed over the metal plate, and a laser diode bar attached to the second adhesion layer. The laser diode bar has a coefficient of thermal expansion (CTE) substantially similar to that of the metal plate.

  15. Modeling of Microwave Semiconductor Diodes

    Directory of Open Access Journals (Sweden)

    Z. Raida

    2008-09-01

    Full Text Available The paper deals with the multi-physical mode-ling of microwave diodes. The electrostatic, drift-diffusion and thermal phenomena are considered in the physical model of the components. The basic semiconductor equati-ons are summarized, and modeling issues are discussed. The simulations of the Gunn Effect in transferred electron devices and the carrier injection effect in PIN diodes are investigated and discussed. The analysis was performed in COMSOL Multiphysics using the finite element method.

  16. Modeling of Microwave Semiconductor Diodes

    OpenAIRE

    Pokorny, M.; Raida, Zbyněk

    2008-01-01

    The paper deals with the multi-physical mode-ling of microwave diodes. The electrostatic, drift-diffusion and thermal phenomena are considered in the physical model of the components. The basic semiconductor equati-ons are summarized, and modeling issues are discussed. The simulations of the Gunn Effect in transferred electron devices and the carrier injection effect in PIN diodes are investigated and discussed. The analysis was performed in COMSOL Multiphysics using the finite element method.

  17. Electron beam potential measurements on an inductive-store, opening-switch accelerator

    International Nuclear Information System (INIS)

    Riordan, J.C.; Goyer, J.R.; Kortbawi, D.; Meachum, J.S.; Mendenhall, R.S.; Roth, I.S.

    1993-01-01

    Direct measurement of the accelerating potential in a relativistic electron beam accelerator is difficult, particularly when the diode is downstream from a plasma opening switch. An indirect potential measurement can be obtained from the high energy tail of the bremsstrahlung spectrum generated as the electron beam strikes the anode. The authors' time-resolved spectrometer contains 7 silicon pin diode detectors filtered with 2 to 15 mm of lead to span an electron energy range of 0.5 to 2 MeV. A Monte-Carlo transport code was used to provide calibration curves, and the resulting potential measurements have been confirmed in experiments on the PITHON accelerator. The spectrometer has recently been deployed on PM1, an inductive-store, opening-switch testbed. The diode voltage measurements from the spectrometer are in good agreement with the diode voltage measured upstream and corrected using transmission line relations. The x-ray signal and spectral voltage rise 10 ns later than the corrected electrical voltage, however, indicating plasma motion between the opening switch and the diode

  18. Memory Applications Using Resonant Tunneling Diodes

    Science.gov (United States)

    Shieh, Ming-Huei

    Resonant tunneling diodes (RTDs) producing unique folding current-voltage (I-V) characteristics have attracted considerable research attention due to their promising application in signal processing and multi-valued logic. The negative differential resistance of RTDs renders the operating points self-latching and stable. We have proposed a multiple -dimensional multiple-state RTD-based static random-access memory (SRAM) cell in which the number of stable states can significantly be increased to (N + 1)^ m or more for m number of N-peak RTDs connected in series. The proposed cells take advantage of the hysteresis and folding I-V characteristics of RTD. Several cell designs are presented and evaluated. A two-dimensional nine-state memory cell has been implemented and demonstrated by a breadboard circuit using two 2-peak RTDs. The hysteresis phenomenon in a series of RTDs is also further analyzed. The switch model provided in SPICE 3 can be utilized to simulate the hysteretic I-V characteristics of RTDs. A simple macro-circuit is described to model the hysteretic I-V characteristic of RTD for circuit simulation. A new scheme for storing word-wide multiple-bit information very efficiently in a single memory cell using RTDs is proposed. An efficient and inexpensive periphery circuit to read from and write into the cell is also described. Simulation results on the design of a 3-bit memory cell scheme using one-peak RTDs are also presented. Finally, a binary transistor-less memory cell which is only composed of a pair of RTDs and an ordinary rectifier diode is presented and investigated. A simple means for reading and writing information from or into the memory cell is also discussed.

  19. Effect of defects on electrical properties of 4H-SiC Schottky diodes

    International Nuclear Information System (INIS)

    Ben Karoui, M.; Gharbi, R.; Alzaied, N.; Fathallah, M.; Tresso, E.; Scaltrito, L.; Ferrero, S.

    2008-01-01

    Most of power electronic circuits use power semiconductor switching devices which ideally present infinite resistance when off, zero resistance when on, and switch instantaneously between those two states. Switches and rectifiers are key components in power electronic systems, which cover a wide range of applications, from power transmission to control electronics and power supplies. Typical power switching devices such as diodes, thyristors, and transistors are based on a monocrystalline silicon semiconductor or silicon carbide. Silicon is less expensive, more widely used, and a more versatile processing material than silicon carbide. The silicon carbide (SiC) has properties that allow devices with high power voltage rating and high operating temperatures. The technology overcomes some crystal growth obstacles, by using the hydrogen in the fabrication of 4H-SiC wafers. The presence of structural defects on 4H-SiC wafers was shown by different techniques such as optical microscopy and scanning electron microscopy. The presence of different SiC polytypes inclusions was found by Raman spectroscopy. Schottky diodes were realized on investigated wafers in order to obtain information about the correlation between those defects and electrical properties of the devices. The diodes with voltage breakdown as 600 V and ideality factor as 1.05 were obtained and characterized after packaging

  20. Switched-mode converters (one quadrant)

    CERN Document Server

    Barrade, P

    2006-01-01

    Switched-mode converters are DC/DC converters that supply DC loads with a regulated output voltage, and protection against overcurrents and short circuits. These converters are generally fed from an AC network via a transformer and a conventional diode rectifier. Switched-mode converters (one quadrant) are non-reversible converters that allow the feeding of a DC load with unipolar voltage and current. The switched-mode converters presented in this contribution are classified into two families. The first is dedicated to the basic topologies of DC/DC converters, generally used for low- to mid-power applications. As such structures enable only hard commutation processes, the main drawback of such topologies is high commutation losses. A typical multichannel evolution is presented that allows an interesting decrease in these losses. Deduced from this direct DC/DC converter, an evolution is also presented that allows the integration of a transformer into the buck and the buck–boost structure. This enables an int...

  1. Comparison of Ion Beam opening switch and plasma opening switch performance

    International Nuclear Information System (INIS)

    Greenly, J.R.; Rondeau, G.D.; Sheldon, H.T.; Dreike, P.L.

    1986-01-01

    The Ion Beam opening switch (IBOS) experiment has shown that an intense charge-neutralized ion beam can carry current across a vacuum magnetically-insulated transmission line and then transfer that current to a downstream load quickly. In the IBOS experiment, a 10 cm wide parallel plate transmission line was fed up to 100 kA peak current by a 4Ω, 100 ns pulser. An ion beam of up to 100 A/cm/sup 2/, 100-300 keV protons or carbon was injected through the anode of the line in a 10 cm x 10 cm region. The line terminated in either a 15 nH short circuit or an electron diode with variable gap. The ion beam switch was able to carry up to 70 kA of line current before load current began to flow. This model is also quantitatively consistent with the observation that switch conduction current is not linear with either injected ion beam current or switch area

  2. Analysis and design of a high-efficiency zero-voltage-switching step ...

    Indian Academy of Sciences (India)

    ... operation of the power switches and output diodes, the proposed ZVS DC–DC converter shows high efficiency. Steady-state analysis of the converter is presented to determine the circuit parameters. A laboratory prototype of the proposed converter is developed, and its experimental results are presented for validation.

  3. Q-switched Ho:YLF laser pumped by a Tm:GdVO4 laser.

    CSIR Research Space (South Africa)

    Esser, MJD

    2009-06-01

    Full Text Available The authors have, through careful analysis of spectroscopic data, designed and demonstrated a diode-end-pumped, quasicontinuous wave Tm:GdVO4 laser operating at 1892 nm in order to pump a Q-switched Ho:YLF laser. The Ho:YLF maximum output energy...

  4. Switched reluctance motor drives

    Indian Academy of Sciences (India)

    Davis RM, Ray WF, Blake RJ 1981 Inverter drive for switched reluctance: circuits and component ratings. Inst. Elec. Eng. Proc. B128: 126-136. Ehsani M. 1991 Position Sensor elimination technique for the switched reluctance motor drive. US Patent No. 5,072,166. Ehsani M, Ramani K R 1993 Direct control strategies based ...

  5. Switch on, switch off: stiction in nanoelectromechanical switches

    KAUST Repository

    Wagner, Till J W

    2013-06-13

    We present a theoretical investigation of stiction in nanoscale electromechanical contact switches. We develop a mathematical model to describe the deflection of a cantilever beam in response to both electrostatic and van der Waals forces. Particular focus is given to the question of whether adhesive van der Waals forces cause the cantilever to remain in the \\'ON\\' state even when the electrostatic forces are removed. In contrast to previous studies, our theory accounts for deflections with large slopes (i.e. geometrically nonlinear). We solve the resulting equations numerically to study how a cantilever beam adheres to a rigid electrode: transitions between \\'free\\', \\'pinned\\' and \\'clamped\\' states are shown to be discontinuous and to exhibit significant hysteresis. Our findings are compared to previous results from linearized models and the implications for nanoelectromechanical cantilever switch design are discussed. © 2013 IOP Publishing Ltd.

  6. Active RF Pulse Compression Using An Electrically Controlled Semiconductor Switch

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiquan; Tantawi, Sami; /SLAC

    2007-01-10

    First we review the theory of active pulse compression systems using resonant delay lines. Then we describe the design of an electrically controlled semiconductor active switch. The switch comprises an active window and an overmoded waveguide three-port network. The active window is based on a four-inch silicon wafer which has 960 PIN diodes. These are spatially combined in an overmoded waveguide. We describe the philosophy and design methodology for the three-port network and the active window. We then present the results of using this device to compress 11.4 GHz RF signals with high compression ratios. We show how the system can be used with amplifier like sources, in which one can change the phase of the source by manipulating the input to the source. We also show how the active switch can be used to compress a pulse from an oscillator like sources, which is not possible with passive pulse compression systems.

  7. Light Emitting Diodes (LEDs)

    Science.gov (United States)

    1997-01-01

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

  8. Push-pull converter with energy saving circuit for protecting switching transistors from peak power stress

    Science.gov (United States)

    Mclyman, W. T. (Inventor)

    1981-01-01

    In a push-pull converter, switching transistors are protected from peak power stresses by a separate snubber circuit in parallel with each comprising a capacitor and an inductor in series, and a diode in parallel with the inductor. The diode is connected to conduct current of the same polarity as the base-emitter juction of the transistor so that energy stored in the capacitor while the transistor is switched off, to protect it against peak power stress, discharges through the inductor when the transistor is turned on, and after the capacitor is discharges through the diode. To return this energy to the power supply, or to utilize this energy in some external circuit, the inductor may be replaced by a transformer having its secondary winding connected to the power supply or to the external circuit.

  9. Development of high power X-band semiconductor microwave switch for pulse compression systems of future linear colliders

    Directory of Open Access Journals (Sweden)

    Fumihiko Tamura

    2002-06-01

    Full Text Available We describe concepts for high power semiconductor rf switches, designed to handle signals at X-band with power level near 100 MW. We describe an abstract design methodology and derive a general scaling law for these switches. We also present a design and experimental work of a switch operating at the TE_{01} mode in overmoded circular waveguides. The switch is composed of an array of tee junction elements that have a p-i-n diode array window in the third arm.

  10. Highly uniform and reliable resistive switching characteristics of a Ni/WOx/p+-Si memory device

    Science.gov (United States)

    Kim, Tae-Hyeon; Kim, Sungjun; Kim, Hyungjin; Kim, Min-Hwi; Bang, Suhyun; Cho, Seongjae; Park, Byung-Gook

    2018-02-01

    In this paper, we investigate the resistive switching behavior of a bipolar resistive random-access memory (RRAM) in a Ni/WOx/p+-Si RRAM with CMOS compatibility. Highly unifrom and reliable bipolar resistive switching characteristics are observed by a DC voltage sweeping and its switching mechanism can be explained by SCLC model. As a result, the possibility of metal-insulator-silicon (MIS) structural WOx-based RRAM's application to Si-based 1D (diode)-1R (RRAM) or 1T (transistor)-1R (RRAM) structure is demonstrated.

  11. Switch mode power supply

    International Nuclear Information System (INIS)

    Kim, Hui Jun

    1993-06-01

    This book concentrates on switch mode power supply. It has four parts, which are introduction of switch mode power supply with DC-DC converter such as Buck converter boost converter, Buck-boost converter and PWM control circuit, explanation for SMPS with DC-DC converter modeling and power mode control, resonance converter like resonance switch, converter, multi resonance converter and series resonance and parallel resonance converters, basic test of SMPS with PWM control circuit, Buck converter, Boost converter, flyback converter, forward converter and IC for control circuit.

  12. BROOKHAVEN: Switched power

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    Hosted by Brookhaven's Center for Accelerator Physics, a recent workshop on switched power techniques attracted a group of specialists to Shelter Island, New York, location of several important physics meetings, including the famous 1947 sessions which helped mould modern quantum electrodynamics. The current interest in switched power stemmed from a series of papers by W. Willis of CERN, starting in 1984. The idea is for stored electrical energy to be suddenly switched on to a transmission line, producing a very short (about 10 ps) electromagnetic pulse in a region traversed by a particle beam

  13. Electromechanical magnetization switching

    Energy Technology Data Exchange (ETDEWEB)

    Chudnovsky, Eugene M. [Department of Physics and Astronomy, Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Jaafar, Reem [Department of Mathematics, Engineering and Computer Science, LaGuardia Community College, The City University of New York, 31-10 Thomson Avenue, Long Island City, New York 11101 (United States)

    2015-03-14

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained.

  14. Electromechanical magnetization switching

    International Nuclear Information System (INIS)

    Chudnovsky, Eugene M.; Jaafar, Reem

    2015-01-01

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained

  15. JUNOS Enterprise Switching

    CERN Document Server

    Reynolds, Harry

    2009-01-01

    JUNOS Enterprise Switching is the only detailed technical book on Juniper Networks' new Ethernet-switching EX product platform. With this book, you'll learn all about the hardware and ASIC design prowess of the EX platform, as well as the JUNOS Software that powers it. Not only is this extremely practical book a useful, hands-on manual to the EX platform, it also makes an excellent study guide for certification exams in the JNTCP enterprise tracks. The authors have based JUNOS Enterprise Switching on their own Juniper training practices and programs, as well as the configuration, maintenanc

  16. Study and fabrication of tunnel diodes made on germanium using a collective planar technique

    International Nuclear Information System (INIS)

    Vrahides, Michel

    1973-01-01

    The main results of the theory on tunnel diodes are presented in the first chapter. From these results are deduced the technological requirements that any fabrication process should meet to make tunnel diodes. These requirements show up that, among the three techniques for junction making (thermal diffusion of impurities, epitaxy, alloying), the last one is presently the best fitted to the fabrication of tunnel junctions. By analyzing the defects created by various alloying technologies presently used, together with a study of the benefits due to a use of chemical photolithography, evaporation under vacuum and masking by deposited oxide, it is possible to design a tentative scheme of a 0.5 ns tunnel diode. Then, in a second chapter, is presented the collective process for fabrication that has been used on monocrystalline, P-type, germanium wafers. 8 000 tunnel diodes may be positioned on a 1.5 inch diameter wafer by using that process. A description of the various apparatus used is also given. The experimental results are described in the third chapter. The influence of the various fabrication parameters on the electrical characteristics of the diodes are discussed. It is shown, by studying the fabrication yields and parameter spreading, that 80 per cent of the diodes exhibit a standard tunnel diode behaviour and that 90 per cent of these present a peak current dispersion less than ± 25 per cent. When measuring at the peak current drifts under temperature stresses, a good analogy with conventional tunnel diode is found. Some measurements of switching times have led to values as low as 0.6 nanoseconds. (author) [fr

  17. Properties of high gain GaAs switches for pulsed power applications

    International Nuclear Information System (INIS)

    Zutavern, F.J.; Loubriel, G.M.; Hjalmarson, H.P.; Mar, A.; Helgeson, W.D.; O'Malley, M.W.; Ruebush, M.H.; Falk, R.A.

    1997-09-01

    High gain GaAs photoconductive semiconductor switches (PCSS) are being used in a variety of electrical and optical short pulse applications. The highest power application, which the authors are developing, is a compact, repetitive, short pulse linear induction accelerator. The array of PCSS, which drive the accelerator, will switch 75 kA and 250 kV in 30 ns long pulses at 50 Hz. The accelerator will produce a 700 kV, 7kA electron beam for industrial and military applications. In the low power regime, these switches are being used to switch 400 A and 5 kV to drive laser diode arrays which produce 100 ps optical pulses. These short optical pulses are for military and commercial applications in optical and electrical range sensing, 3D laser radar, and high speed imaging. Both types of these applications demand a better understanding of the switch properties to increase switch lifetime, reduce jitter, optimize optical triggering, and improve overall switch performance. These applications and experiments on the fundamental behavior of high gain GaAs switches will be discussed. Open shutter, infra-red images and time-resolved images of the current filaments, which form during high gain switching, will be presented. Results from optical triggering experiments to produce multiple, diffuse filaments for high current repetitive switching will be described

  18. Properties of high gain GaAs switches for pulsed power applications

    Energy Technology Data Exchange (ETDEWEB)

    Zutavern, F.J.; Loubriel, G.M.; Hjalmarson, H.P.; Mar, A.; Helgeson, W.D.; O`Malley, M.W.; Ruebush, M.H. [Sandia National Labs., Albuquerque, NM (United States); Falk, R.A. [OptoMetrix, Inc., Renton, WA (United States)

    1997-09-01

    High gain GaAs photoconductive semiconductor switches (PCSS) are being used in a variety of electrical and optical short pulse applications. The highest power application, which the authors are developing, is a compact, repetitive, short pulse linear induction accelerator. The array of PCSS, which drive the accelerator, will switch 75 kA and 250 kV in 30 ns long pulses at 50 Hz. The accelerator will produce a 700 kV, 7kA electron beam for industrial and military applications. In the low power regime, these switches are being used to switch 400 A and 5 kV to drive laser diode arrays which produce 100 ps optical pulses. These short optical pulses are for military and commercial applications in optical and electrical range sensing, 3D laser radar, and high speed imaging. Both types of these applications demand a better understanding of the switch properties to increase switch lifetime, reduce jitter, optimize optical triggering, and improve overall switch performance. These applications and experiments on the fundamental behavior of high gain GaAs switches will be discussed. Open shutter, infra-red images and time-resolved images of the current filaments, which form during high gain switching, will be presented. Results from optical triggering experiments to produce multiple, diffuse filaments for high current repetitive switching will be described.

  19. Power saving regulated light emitting diode circuit

    International Nuclear Information System (INIS)

    Haville, G. D.

    1985-01-01

    A power saving regulated light source circuit, comprising a light emitting diode (LED), a direct current source and a switching transistor connected in series with the LED, a control voltage producing resistor connected in series with the LED to produce a control voltage corresponding to the current through the LED, a storage capacitor connected in parallel with the series combination of the LED and the resistor, a comparator having its output connected to the input of the transistor, the comparator having a reference input and a control input, a stabilized biasing source for supplying a stabilized reference voltage to the reference input, the control input of the comparator being connected to the control voltage producing resistor, the comparator having a high output state when the reference voltage exceeds the control voltage while having a low output state when the control voltage exceeds the reference voltage, the transistor being conductive in response to the high state while being nonconductive in response to the low state, the transistor when conductive being effective to charge the capacitor and to increase the control voltage, whereby the comparator is cycled between the high and low output states while the transistor is cycled between conductive and nonconductive states

  20. Laser Diode Beam Basics, Manipulations and Characterizations

    CERN Document Server

    Sun, Haiyin

    2012-01-01

    Many optical design technical books are available for many years which mainly deal with image optics design based on geometric optics and using sequential raytracing technique. Some books slightly touched laser beam manipulation optics design. On the other hand many books on laser diodes have been published that extensively deal with laser diode physics with little touching on laser diode beam manipulations and characterizations. There are some internet resources dealing with laser diode beams. However, these internet resources have not covered enough materials with enough details on laser diode beam manipulations and characterizations. A technical book concentrated on laser diode beam manipulations and characterizations can fit in to the open and provide useful information to laser diode users. Laser Diode Beam Basics, Manipulations and  Characterizations is concentrated on the very practical side of the subject, it only discusses the basic physics and mathematics that are necessary for the readers in order...

  1. A photochromic diode with a continuum of intermediate states: towards high density multilevel storage.

    Science.gov (United States)

    Shallcross, R Clayton; Körner, Peter O; Maibach, Eduard; Köhnen, Anne; Meerholz, Klaus

    2013-09-14

    A continuum of intermediate states (current levels) is demonstrated for an organic diode utilizing a photochromic (dithienylethene) switching layer. Specific intermediate states can be attained by controlling the fraction of closed isomer (X) in the transduction layer, affording a novel methodology for multilevel storage applications. The analog response of the device is discussed in terms of the concentration and morphology of closed dithienylethene isomer, which can be accessed via optical and electrical switching reactions. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Green high-power tunable external-cavity GaN diode laser at 515 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-01-01

    A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam...... incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2.1 nm is obtained. This constitutes the highest output power from a tunable green diode...... laser system....

  3. Colour-tunable light-emitting diodes based on InP/GaP nanostructures

    International Nuclear Information System (INIS)

    Hatami, Fariba; Masselink, W Ted; Harris, James S

    2006-01-01

    We describe a novel colour-tunable light-emitting diode whose operation is based on direct band-gap emission from coupled configurations of InP quantum dots and quantum wells embedded in GaP. The control of the emission colour stems from a marked difference in the current dependence of intensities of two different emission processes. At lower currents, the emission is dominated by the 720 nm luminescence from the quantum dots and appears red; at higher currents, the emission is dominated by the 550 nm quantum-well luminescence and the perceived colour is green. Thus, we are able to tune the colour of such diodes from red to green by means of drive current. A multi-colour pixel can be realized by a single diode, with rapid switching between colour states to provide a range of colour mix

  4. Few-photon optical diode

    OpenAIRE

    Roy, Dibyendu

    2010-01-01

    We propose a novel scheme of realizing an optical diode at the few-photon level. The system consists of a one-dimensional waveguide coupled asymmetrically to a two-level system. The two or multi-photon transport in this system is strongly correlated. We derive exactly the single and two-photon current and show that the two-photon current is asymmetric for the asymmetric coupling. Thus the system serves as an optical diode which allows transmission of photons in one direction much more efficie...

  5. Spin-photon entangling diode

    DEFF Research Database (Denmark)

    Flindt, Christian; Sørensen, A. S.; Lukin, M. D.

    2007-01-01

    We propose a semiconductor device that can electrically generate entangled electron spin-photon states, providing a building block for entanglement of distant spins. The device consists of a p-i-n diode structure that incorporates a coupled double quantum dot. We show that electronic control...... of the diode bias and local gating allow for the generation of single photons that are entangled with a robust quantum memory based on the electron spins. Practical performance of this approach to controlled spin-photon entanglement is analyzed....

  6. uv preilluminated gas switches

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

    1980-06-03

    We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10/sup 12/ amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters.

  7. Switching power supply filter

    Science.gov (United States)

    Kumar, Prithvi R. (Inventor); Abare, Wayne (Inventor)

    1989-01-01

    A filter for a switching power supply. The filter includes a common mode inductor with coil configurations allowing differential mode current from a dc source to pass through but attenuating common mode noise from the power supply so that the noise does not reach the dc source. The invention also includes the use of feed through capacitors at the switching power supply input terminals to provide further high-frequency noise attenuation.

  8. uv preilluminated gas switches

    International Nuclear Information System (INIS)

    Bradley, L.P.; Orham, E.L.; Stowers, I.F.; Braucht, J.R.

    1980-01-01

    We have designed, built, and characterized uv preilluminated gas switches for a trigger circuit and a low inductance discharge circuit. These switches have been incorporated into a 54 x 76 x 150 cm pulser module to produce a 1 Ma output current rising at 5 x 10 12 amps/sec with 1 ns jitter. Twenty such modules will be used on the Nova Inertial Confinement Fusion Laser System for plasma retropulse shutters

  9. Photonics in switching

    CERN Document Server

    Midwinter, John E; Kelley, Paul

    1993-01-01

    Photonics in Switching provides a broad, balanced overview of the use of optics or photonics in switching, from materials and devices to system architecture. The chapters, each written by an expert in the field, survey the key technologies, setting them in context and highlighting their benefits and possible applications. This book is a valuable resource for those working in the communications industry, either at the professional or student level, who do not have extensive background knowledge or the underlying physics of the technology.

  10. Extraction magnetically insulated diode studies on Gamble II

    International Nuclear Information System (INIS)

    Neri, J.M.; Boller, J.R.; Ottinger, P.F.; Stephanakis, S.J.; Greenly, J.

    1993-01-01

    An extraction Magnetically Insulated Diode (MID) with anode and cathode magnetic field coils has been tested on the NRL Gamble II accelerator. The purpose of the experiments is to develop an annular, intense ion beam source for testing ion beam transport physics related to light ion inertial confinement fusion. Initial experiments have been performed with surface flashover ion sources. The experimental challenge has been to obtain a tuning of the 4 magnetic field coils that results in a minimum turn-on time of the ion source and acceptable coupling to the accelerator. Results from several different geometries of magnetic field will be presented. The principal diode diagnostics are the total diode current, net ion current, and corrected diode voltage. Calculations of the magnetic field strength and geometry are performed with the ATHETA code. An active anode ion source is also under development. The initial portion of the accelerator pulse is diverted with a plasma opening switch (POS) and passed through a thin foil that will become the ion source. The foil is swiftly heated by the current pulse and gas is desorbed or diffused from the foil into the anode-cathode gap. The gas is then broken down by the current pulse, forming a dense plasma source on the anode surface. Two different foils are being used. A thin aluminum foil will work with desorbed gases, and provide a beam that is predominately protons. A hydrogen loaded titanium foil, with a paladium overcoating, will use diffused hydrogen, and produce a high purity proton beam. The net result of the POS and active anode plasma source should be much faster ion turn-on time, and better coupling of the ion source to the accelerator. Preliminary results with the active anode sources will be presented

  11. A high speed, medium voltage pulse amplifier for diode reverse transient measurements

    Science.gov (United States)

    Chudobiak, Michael J.

    1995-11-01

    A dc-coupled nonlinear pulse amplifier circuit is presented. The circuit presented can produce 40 V peak-to-peak pulses with 3 ns rise and fall times. This speed is obtained by using class D transistor amplifier stages. This circuit is shown to be useful for measuring the reverse recovery transients of fast switching diodes such as the 1N4148, and fast recovery power rectifiers.

  12. Optical switching systems using nanostructures

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    2004-01-01

    High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems.......High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems....

  13. Understanding and Supporting Window Switching

    NARCIS (Netherlands)

    Tak, S.

    2011-01-01

    Switching between windows on a computer is a frequent activity, but finding and switching to the target window can be inefficient. This thesis aims to better un-derstand and support window switching. It explores two issues: (1) the lack of knowledge of how people currently interact with and switch

  14. Low inductance gas switching.

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, Ray; Harjes, Henry Charles III; Wallace, Zachariah; Elizondo, Juan E.

    2007-10-01

    The laser trigger switch (LTS) is a key component in ZR-type pulsed power systems. In ZR, the pulse rise time through the LTS is > 200 ns and additional stages of pulse compression are required to achieve the desired <100 ns rise time. The inductance of the LTS ({approx}500nH) in large part determines the energy transfer time through the switch and there is much to be gained in improving system performance and reducing system costs by reducing this inductance. The current path through the cascade section of the ZR LTS is at a diameter of {approx} 6-inches which is certainly not optimal from an inductance point of view. The LTS connects components of much greater diameter (typically 4-5 feet). In this LDRD the viability of switch concepts in which the diameter of cascade section is greatly increased have been investigated. The key technical question to be answered was, will the desired multi-channel behavior be maintained in a cascade section of larger diameter. This LDRD proceeded in 2 distinct phases. The original plan for the LDRD was to develop a promising switch concept and then design, build, and test a moderate scale switch which would demonstrate the key features of the concept. In phase I, a switch concept which meet all electrical design criteria and had a calculated inductance of 150 nH was developed. A 1.5 MV test switch was designed and fabrication was initiated. The LDRD was then redirected due to budgetary concerns. The fabrication of the switch was halted and the focus of the LDRD was shifted to small scale experiments designed to answer the key technical question concerning multi-channel behavior. In phase II, the Multi-channel switch test bed (MCST) was designed and constructed. The purpose of MCST was to provide a versatile, fast turn around facility for the study the multi-channel electrical breakdown behavior of a ZR type cascade switch gap in a parameter space near that of a ZR LTS. Parameter scans on source impedance, gap tilt, gap spacing and

  15. A radiation hard vacuum switch

    Science.gov (United States)

    Boettcher, G.E.

    1988-07-19

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

  16. Characterization of Stock Blu-ray diodes

    Science.gov (United States)

    Cunningham, Mark; Archibald, James; Erickson, Christopher; Durfee, Dallin

    2010-10-01

    I am developing a process to test and characterize diodes of unknown wavelengths. using a B&WTEK Spectrometer we are characterizing the wavelength of 405 nm blu-ray diodes purchased in bulk. With the known error in production of the Diode Lasers we are hoping to find a diode at 408 nm to use in driving a raman transition between hyperfine states of strontium 87 ions. The bulk of the project is a java program that communicates with the spectrometer and graphically displays the intensities of the wavelengths from the laser diodes.

  17. Plasma opening switch for long-pulse intense ion beam

    International Nuclear Information System (INIS)

    Davis, H.A.; Mason, R.J.; Bartsch, R.R.; Greenly, J.B.; Rej, D.J.

    1993-01-01

    A Plasma Opening Switch (POS) is being developed at Los Alamos, as part of an intense ion beam experiment with special application to materials processing. The switch must conduct up to 100 kA for 400 ns, and open quicky to avoid premature gap closure in the ion beam diode load. Power multiplication is not a necessity, but prepulse suppression is. A positive central polarity is desirable, since with it an ion beam can be conveniently launched beyond the switch from the central anode toward a negatively charged target. Using traditional scaling rules, a POS was designed with a 1.25 cm radius inner anode, and a 5.0 cm radius outer cathode. This has been constructed, and subjected to circuit, and simulational analysis. The computations are being performed with the 2D ANTHEM implicit code. Preliminary results show a marked difference in switching dynamics, when the central positive polarity is used in place of the more conventional opposite choice. Opening is achieved by the fast development of a central anode magnetic layer, rather than by the more conventional slow evolution of a cathode gap. With the central anode, higher fill densities are needed to achieve desired conduction times. This has suggested switch design improvements, which are discussed

  18. Millimeter-scale liquid metal droplet thermal switch

    Science.gov (United States)

    Yang, Tianyu; Kwon, Beomjin; Weisensee, Patricia B.; Kang, Jin Gu; Li, Xuejiao; Braun, Paul; Miljkovic, Nenad; King, William P.

    2018-02-01

    Devices capable of actively controlling heat flow have been desired by the thermal management community for decades. The need for thermal control has become particularly urgent with power densification resulting in devices with localized heat fluxes as high as 1 kW/cm2. Thermal switches, capable of modulating between high and low thermal conductances, enable the partitioning and active control of heat flow pathways. This paper reports a millimeter-scale thermal switch with a switching ratio >70, at heat fluxes near 10 W/cm2. The device consists of a silicone channel filled with a reducing liquid or vapor and an immersed liquid metal Galinstan slug. Galinstan has a relatively high thermal conductivity (≈16.5 W/mK at room temperature), and its position can be manipulated within the fluid channel, using either hydrostatic pressure or electric fields. When Galinstan bridges the hot and cold reservoirs (the "ON" state), heat flows across the channel. When the hot and cold reservoirs are instead filled with the encapsulating liquid or vapor (the "OFF" state), the cross-channel heat flow significantly reduces due to the lower thermal conductivity of the solution (≈0.03-0.6 W/mK). We demonstrate switching ratios as high as 15.6 for liquid filled channels and 71.3 for vapor filled channels. This work provides a framework for the development of millimeter-scale thermal switches and diodes capable of spatial and temporal control of heat flows.

  19. Method and system for a gas tube switch-based voltage source high voltage direct current transmission system

    Science.gov (United States)

    She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui; Zhang, Di; Sommerer, Timothy John; Bray, James William

    2016-12-13

    A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of the one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.

  20. High-Speed and Low-Energy Flip-Flop Operation of Asymmetric Active-Multimode Interferometer Bi-Stable Laser Diodes

    DEFF Research Database (Denmark)

    Jiang, Haisong; Chaen, Yutaka; Hagio, Takuma

    2011-01-01

    High-speed (121/25 ps rise/fall time) and low-switching energy (7.1 and 3.4 fJ) alloptical flip-flop operation of single-wavelength high-mesa asymmetric active-MMI bi-stable laser diodes is demonstrated for the first time using 25 ps long switching pulses.......High-speed (121/25 ps rise/fall time) and low-switching energy (7.1 and 3.4 fJ) alloptical flip-flop operation of single-wavelength high-mesa asymmetric active-MMI bi-stable laser diodes is demonstrated for the first time using 25 ps long switching pulses....

  1. Energy reversible switching from amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-08-01

    We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young\\'s modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young\\'s modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

  2. Microfabricated triggered vacuum switch

    Science.gov (United States)

    Roesler, Alexander W [Tijeras, NM; Schare, Joshua M [Albuquerque, NM; Bunch, Kyle [Albuquerque, NM

    2010-05-11

    A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

  3. Switching power supply

    Science.gov (United States)

    Mihalka, A.M.

    1984-06-05

    The invention is a repratable capacitor charging, switching power supply. A ferrite transformer steps up a dc input. The transformer primary is in a full bridge configuration utilizing power MOSFETs as the bridge switches. The transformer secondary is fed into a high voltage, full wave rectifier whose output is connected directly to the energy storage capacitor. The transformer is designed to provide adequate leakage inductance to limit capacitor current. The MOSFETs are switched to the variable frequency from 20 to 50 kHz to charge a capacitor from 0.6 kV. The peak current in a transformer primary and secondary is controlled by increasing the pulse width as the capacitor charges. A digital ripple counter counts pulses and after a preselected desired number is reached an up-counter is clocked.

  4. Optical computer switching network

    Science.gov (United States)

    Clymer, B.; Collins, S. A., Jr.

    1985-01-01

    The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

  5. Three new DC-to-DC Single-Switch Converters

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2017-06-01

    Full Text Available This paper presents a new family of three previously unidentified dc-to-dc converters, buck, boost, and buck-boost voltage-transfer-function topologies, which offer advantageous transformer coupling features and low capacitor dc voltage stressing. The three single-switch, single-diode, converters offer the same features as basic dc-to-dc converters, such as the buck function with continuous output current and the boost function with continuous input current. Converter time-domain simulations and experimental results (including transformer coupling support and extol the dc-to-dc converter concepts and analysis presented.

  6. Optical Packet Switching Demostrator

    DEFF Research Database (Denmark)

    Mortensen, Brian Bach; Berger, Michael Stübert

    2002-01-01

    In the IST project DAVID (data and voice integration over DWDM) work is carried out defining possible architectures of future optical packet switched networks. The feasibility of the architecture is to be verified in a demonstration set-up. This article describes the demonstrator set-up and the m......In the IST project DAVID (data and voice integration over DWDM) work is carried out defining possible architectures of future optical packet switched networks. The feasibility of the architecture is to be verified in a demonstration set-up. This article describes the demonstrator set...

  7. Plasma Switch Development.

    Science.gov (United States)

    1984-06-08

    ACCION NO. 3. RCIPIENT’S CATALOG NUMBER 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED PLASMA SWITCH DEVELOPMENT Final Report: 02/26/82 thru...with an inductive energy store. At present, the are summarized state-of-he- art of high-power repetitive opening or doming switches is limited to...Alexandria, VA 22304. Figure 7 Is a circuit diagram of the proposed system. The desired load pulse parameters art -100- e References 1. R.D. Ford, 0. Jenkins

  8. Bearingless switched reluctance motor

    Science.gov (United States)

    Morrison, Carlos R. (Inventor)

    2004-01-01

    A switched reluctance motor has a stator with a first set of poles directed toward levitating a rotor horizontally within the stator. A disc shaped portion of a hybrid rotor is affected by the change in flux relative to the current provided at these levitation poles. A processor senses the position of the rotor and changes the flux to move the rotor toward center of the stator. A second set of poles of the stator are utilized to impart torque upon a second portion of the rotor. These second set of poles are driven in a traditional switched reluctance manner by the processor.

  9. Planar C-Band Antenna with Electronically Controllable Switched Beams

    Directory of Open Access Journals (Sweden)

    Mariano Barba

    2009-01-01

    Full Text Available The design, manufacturing, and measurements of a switchable-beam antenna at 3.5 GHz for WLL or Wimax base station antennas in planar technology are presented. This antenna performs a discrete beam scan of a 60∘ sector in azimuth and can be easily upgraded to 5 or more steps. The switching capabilities have been implemented by the inclusion of phase shifters based on PIN diodes in the feed network following a strategy that allows the reduction of the number of switches compared to a classic design. The measurements show that the design objectives have been achieved and encourage the application of the acquired experience in antennas for space applications, such as X-band SAR and Ku-band DBS.

  10. Characterisation of Silicon Pad Diodes

    CERN Document Server

    Hodson, Thomas Connor

    2017-01-01

    Silicon pad sensors are used in high luminosity particle detectors because of their excellent timing resolution, radiation tolerance and possible high granularity. The effect of different design decisions on detector performance can be investigated nondestructively through electronic characterisation of the sensor diodes. Methods for making accurate measurements of leakage current and cell capacitance are described using both a standard approach with tungsten needles and an automated approach with a custom multiplexer and probing setup.

  11. Ultrafast gas switching experiments

    International Nuclear Information System (INIS)

    Frost, C.A.; Martin, T.H.; Patterson, P.E.; Rinehart, L.F.; Rohwein, G.J.; Roose, L.D.; Aurand, J.F.; Buttram, M.T.

    1993-01-01

    We describe recent experiments which studied the physics of ultrafast gas breakdown under the extreme overvoltages which occur when a high pressure gas switch is pulse charged to hundreds of kV in 1 ns or less. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes Khz at > 100 kV/m E field

  12. Photonic MEMS switch applications

    Science.gov (United States)

    Husain, Anis

    2001-07-01

    As carriers and service providers continue their quest for profitable network solutions, they have shifted their focus from raw bandwidth to rapid provisioning, delivery and management of revenue generating services. Inherently transparent to data rate the transmission wavelength and data format, MEMS add scalability, reliability, low power and compact size providing flexible solutions to the management and/or fiber channels in long haul, metro, and access networks. MEMS based photonic switches have gone from the lab to commercial availability and are now currently in carrier trials and volume production. 2D MEMS switches offer low up-front deployment costs while remaining scalable to large arrays. They allow for transparent, native protocol transmission. 2D switches enable rapid service turn-up and management for many existing and emerging revenue rich services such as storage connectivity, optical Ethernet, wavelength leasing and optical VPN. As the network services evolve, the larger 3D MEMS switches, which provide greater scalability and flexibility, will become economically viable to serve the ever-increasing needs.

  13. Search and switching costs

    NARCIS (Netherlands)

    Siekman, Wilhelm Henricus

    2016-01-01

    This thesis analyses markets with search and with switching costs. It provides insights in several important issues in search markets, including how loss aversion may affect consumer behavior and firm conduct, and how prices, welfare, and profits may change when an intermediating platform orders

  14. The Octopus switch

    NARCIS (Netherlands)

    Havinga, Paul J.M.

    2000-01-01

    This chapter1 discusses the interconnection architecture of the Mobile Digital Companion. The approach to build a low-power handheld multimedia computer presented here is to have autonomous, reconfigurable modules such as network, video and audio devices, interconnected by a switch rather than by a

  15. Stochastic Switching Dynamics

    DEFF Research Database (Denmark)

    Simonsen, Maria

    mode control. It is investigated how to understand and interpret solutions to models of switched systems, which are exposed to discontinuous dynamics and uncertainties (primarily) in the form of white noise. The goal is to gain knowledge about the performance of the system by interpreting the solution...

  16. N-state random switching based on quantum tunnelling

    Science.gov (United States)

    Bernardo Gavito, Ramón; Jiménez Urbanos, Fernando; Roberts, Jonathan; Sexton, James; Astbury, Benjamin; Shokeir, Hamzah; McGrath, Thomas; Noori, Yasir J.; Woodhead, Christopher S.; Missous, Mohamed; Roedig, Utz; Young, Robert J.

    2017-08-01

    In this work, we show how the hysteretic behaviour of resonant tunnelling diodes (RTDs) can be exploited for new functionalities. In particular, the RTDs exhibit a stochastic 2-state switching mechanism that could be useful for random number generation and cryptographic applications. This behaviour can be scaled to N-bit switching, by connecting various RTDs in series. The InGaAs/AlAs RTDs used in our experiments display very sharp negative differential resistance (NDR) peaks at room temperature which show hysteresis cycles that, rather than having a fixed switching threshold, show a probability distribution about a central value. We propose to use this intrinsic uncertainty emerging from the quantum nature of the RTDs as a source of randomness. We show that a combination of two RTDs in series results in devices with three-state outputs and discuss the possibility of scaling to N-state devices by subsequent series connections of RTDs, which we demonstrate for the up to the 4-state case. In this work, we suggest using that the intrinsic uncertainty in the conduction paths of resonant tunnelling diodes can behave as a source of randomness that can be integrated into current electronics to produce on-chip true random number generators. The N-shaped I-V characteristic of RTDs results in a two-level random voltage output when driven with current pulse trains. Electrical characterisation and randomness testing of the devices was conducted in order to determine the validity of the true randomness assumption. Based on the results obtained for the single RTD case, we suggest the possibility of using multi-well devices to generate N-state random switching devices for their use in random number generation or multi-valued logic devices.

  17. Control synthesis of switched systems

    CERN Document Server

    Zhao, Xudong; Niu, Ben; Wu, Tingting

    2017-01-01

    This book offers its readers a detailed overview of the synthesis of switched systems, with a focus on switching stabilization and intelligent control. The problems investigated are not only previously unsolved theoretically but also of practical importance in many applications: voltage conversion, naval piloting and navigation and robotics, for example. The book considers general switched-system models and provides more efficient design methods to bring together theory and application more closely than was possible using classical methods. It also discusses several different classes of switched systems. For general switched linear systems and switched nonlinear systems comprising unstable subsystems, it introduces novel ideas such as invariant subspace theory and the time-scheduled Lyapunov function method of designing switching signals to stabilize the underlying systems. For some typical switched nonlinear systems affected by various complex dynamics, the book proposes novel design approaches based on inte...

  18. Characterisation of Plasma Filled Rod Pinch electron beam diode operation

    Science.gov (United States)

    MacDonald, James; Bland, Simon; Chittenden, Jeremy

    2016-10-01

    The plasma filled rod pinch diode (aka PFRP) offers a small radiographic spot size and a high brightness source. It operates in a very similar to plasma opening switches and dense plasma focus devices - with a plasma prefill, supplied via a number of simple coaxial plasma guns, being snowploughed along a thin rod cathode, before detaching at the end. The aim of this study is to model the PFRP and understand the factors that affect its performance, potentially improving future output. Given the dependence on the PFRP on the prefill, we are making detailed measurements of the density (1015-1018 cm-3), velocity, ionisation and temperature of the plasma emitted from a plasma gun/set of plasma guns. This will then be used to provide initial conditions to the Gorgon 3D MHD code, and the dynamics of the entire rod pinch process studied.

  19. Implementation of Single Phase Soft Switched PFC Converter for Plug-in-Hybrid Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Aiswariya Sekar

    2015-11-01

    Full Text Available This paper presents a new soft switching boost converter with a passive snubber cell without additional active switches for battery charging systems. The proposed snubber finds its application in the front-end ac-dc converter of Plug-in Hybrid Electric Vehicle (PHEV battery chargers. The proposed auxiliary snubber circuit consists of an inductor, two capacitors and two diodes. The new converter has the advantages of continuous input current, low switching stresses, high voltage gain without extreme duty cycle, minimized charger size and charging time and fewer amounts of cost and electricity drawn from the utility at higher switching frequencies. The switch is made to turn ON by Zero Current Switching (ZCS and turn OFF by Zero Voltage Switching (ZVS. The detailed steady state analysis of the novel ac-dc Zero Current- Zero Voltage Switching (ZC-ZVS boost Power Factor Correction (PFC converter is presented with its operating principle. The experimental prototype of 20 kHz, 100 W converter verifies the theoretical analysis. The power factor of the prototype circuit reaches near unity with an efficiency of 97%, at nominal output power for a ±10% variation in the input voltage and ±20% variation in the snubber component values.

  20. Electromagnetic wave analogue of electronic diode

    OpenAIRE

    Shadrivov, Ilya V.; Powell, David A.; Kivshar, Yuri S.; Fedotov, Vassili A.; Zheludev, Nikolay I.

    2010-01-01

    An electronic diode is a nonlinear semiconductor circuit component that allows conduction of electrical current in one direction only. A component with similar functionality for electromagnetic waves, an electromagnetic isolator, is based on the Faraday effect of the polarization state rotation and is also a key component of optical and microwave systems. Here we demonstrate a chiral electromagnetic diode, which is a direct analogue of an electronic diode: its functionality is underpinned by ...

  1. Reliable wide-range diode thermometry

    International Nuclear Information System (INIS)

    Krause, J.K.; Swinehart, P.R.

    1986-01-01

    A review of diode thermometry is given, pointing out its advantages and limitations. Research and development efforts towards improving the diode temperature sensor are outlined and preliminary data are presented on a recently introduced diode temperature sensor made of GaAlAs. Important aspects to consider in the calibration of temperature sensors and also the limitations in using liquid cryogens as calibration check points are described

  2. Thermic diode performance characteristics and design manual

    Science.gov (United States)

    Bernard, D. E.; Buckley, S.

    1979-01-01

    Thermic diode solar panels are a passive method of space and hot water heating using the thermosyphon principle. Simplified methods of sizing and performing economic analyses of solar heating systems had until now been limited to passive systems. A mathematical model of the thermic diode including its high level of stratification has been constructed allowing its performance characteristics to be studied. Further analysis resulted in a thermic diode design manual based on the f-chart method.

  3. Review of opening switch technology

    International Nuclear Information System (INIS)

    Kristiansen, M.; Schoenbach, K.M.; Schaefer, G.

    1984-01-01

    Review of opening switch technology is given. Classification of open switches applied in pulsed power technology is presented. The most familiar opening switches are fuses. It is shown that a strong oxidizer (H 2 O 2 in water), especially in combination with wires of Al, increases the maximum voltage. Thermally driven opening switches are the result of attempts to achive the speed and economy of fuse opening switches but with added advantage of repetitive operation. The search for coordinate materials for this type of opening switch is in its infancy and it is difficult to predict how successful such a switch may be. Explosive opening switches offer the possibility of precise timing and permit the delay before explosion to be controlled independently of current flowing through the switch. Plasma guns, dense plasma focus and MHD switches are also considered. Diffuse discharge opening switches are attractive for repetitive operation. The plasma erosion switch operates on a very short time scale of 10 ns to 100 ns, both to regard to conduction and opening times

  4. Novel diode laser system for photodynamic therapy

    DEFF Research Database (Denmark)

    Samsøe, E.; Petersen, P.M.; Andersen, Peter E.

    2001-01-01

    In this paper a novel diode laser system for photodynamic therapy is demonstrated. The system is based on linear spatial filtering and optical phase conjugate feedback from a photorefractive BaTiO3 crystal. The spatial coherence properties of the diode laser are significantly improved. The system...... is extracted in a high-quality beam and 80 percent of the output power is extracted through the fiber. The power transmitted through tile fiber scales linearly with the power of the laser diode. which means that a laser diode emitting 1.7 W multi-mode radiation would provide 1 W of optical power through a 50...

  5. Focusing experiments with light ion diodes

    International Nuclear Information System (INIS)

    Johnson, D.L.

    1978-01-01

    A review of recent experimental and theoretical work at Sandia Laboratories on magnetically insulated single stage ion diodes for inertial confinement fusion experiments is presented. The production, focusing, and numerical simulation of a 0.5 TW annular proton beam using the Proto I dual transmission line generator is described. The modular magnetically insulated ion diode for the Hydra generator is also described along with recent experimental results. A brief description of how an array of modular diodes similar to the Hydra magnetically insulated diode could be used on the EBFA I generator for breakeven fusion experiments is presented

  6. Abacus switch: a new scalable multicast ATM switch

    Science.gov (United States)

    Chao, H. Jonathan; Park, Jin-Soo; Choe, Byeong-Seog

    1995-10-01

    This paper describes a new architecture for a scalable multicast ATM switch from a few tens to thousands of input ports. The switch, called Abacus switch, has a nonblocking memoryless switch fabric followed by small switch modules at the output ports; the switch has input and output buffers. Cell replication, cell routing, output contention resolution, and cell addressing are all performed distributedly in the Abacus switch so that it can be scaled up to thousnads input and output ports. A novel algorithm has been proposed to resolve output port contention while achieving input and output ports. A novel algorithm has been proposed to reolve output port contention while achieving input buffers sharing, fairness among the input ports, and multicast call splitting. The channel grouping concept is also adopted in the switch to reduce the hardware complexity and improve the switch's throughput. The Abacus switch has a regular structure and thus has the advantages of: 1) easy expansion, 2) relaxed synchronization for data and clock signals, and 3) building the switch fabric using existing CMOS technology.

  7. Modeling and Simulation of a 5.8kV SiC PiN Diode for Inductive Pulsed Plasma Thruster Applications

    Science.gov (United States)

    Toftul, Alexandra; Hudgins, Jerry L.; Polzin, Kurt A.; Martin, Adam K.

    2014-01-01

    Current ringing in an Inductive Pulsed Plasma Thruster (IPPT) can lead to reduced energy efficiency, excess heating, and wear on circuit components such as capacitors and solid state devices. Clamping off the current using a fast turn-off power diode is an effective way to reduce current ringing and increase energy efficiency. A diode with a shorter reverse recovery time will allow the least amount of current to ring back through the circuit, as well as minimize switching losses. The reverse recovery response of a new 5.8 kilovolt SiC PiN diode from Cree, Inc. in the IPPT plasma drive circuit is investigated using a physicsbased Simulink model, and compared with that of a 5SDF 02D6004 5.5 kilovolt fast-switching Si diode from ABB. Parameter extraction was carried out for each diode using both datasheet specifications and experimental waveforms, in order to most accurately adapt the model to the specific device. Further experimental data will be discussed using a flat-plate IPPT developed at NASA Marshall Space Flight Center and used to verify the simulation results. A final quantitative measure of circuit efficiency will be described for both the Si and SiC diode configuration.

  8. High step-up isolated efficient single switch DC-DC converter for renewable energy source

    Directory of Open Access Journals (Sweden)

    A. Gopi

    2014-12-01

    Full Text Available In this paper, an isolated high step-up single switch DC-DC converter for renewable energy source is proposed. In the proposed converter high step-up voltage is obtained by single power switching technique that operates low duty cycle with isolated transformer inductors and switched capacitors and power diodes. The disadvantage of conventional converters is that it has high duty ratio and high voltage stress on power devices with less efficiency. The proposed converter eliminates the switching losses and recycles the leakage energy which includes reverse recovery energy of the power diode by using passive clamp circuit. To achieve high output voltage gain, the isolated transformer primary terminal and secondary terminal are connected in series during switching operation. PSIM software has been used for simulation. Simulation circuit is analyzed at 40Vdc/400Vdc, 200 W and this operation is validated by implementing in the hardware model at 12Vdc/120Vdc, 60 W.

  9. Novel, Four-Switch, Z-Source Three-Phase Inverter

    DEFF Research Database (Denmark)

    Antal, Robert; Muntean, Nicolae; Boldea, Ion

    2010-01-01

    This paper presents a new z-source three phase inverter topology. The proposed topology combines the advantages of a traditional four-switch three-phase inverter with the advantages of the z impedance network (one front-end diode, two inductors and two X connected capacitors). This new topology......) value as in six switch standard three-phase inverter. The article presents the derivation of the equations describing the operation of the converter based on space vector analysis, validation through digital simulations in PSIM and preliminary experimental results on a laboratory setup with a dsPIC30F...

  10. High voltage, high power operation of the plasma erosion opening switch

    International Nuclear Information System (INIS)

    Neri, J.M.; Boller, J.R.; Ottinger, P.F.; Weber, B.V.; Young, F.C.

    1987-01-01

    A Plasma Erosion Opening Switch (PEOS) is used as the opening switch for a vacuum inductive storage system driven by a 1.8-MV, 1.6-TW pulsed power generator. A 135-nH vacuum inductor is current charged to ∼750 kA in 50 ns through the closed PEOS which then opens in <10 ns into an inverse ion diode load. Electrical diagnostics and nuclear activations from ions accelerated in the diode yield a peak load voltage (4.25 MV) and peak load power (2.8 TW) that are 2.4 and 1.8 times greater than ideal matched load values for the same generator pulse

  11. Optical fiber switch

    Science.gov (United States)

    Early, James W.; Lester, Charles S.

    2002-01-01

    Optical fiber switches operated by electrical activation of at least one laser light modulator through which laser light is directed into at least one polarizer are used for the sequential transport of laser light from a single laser into a plurality of optical fibers. In one embodiment of the invention, laser light from a single excitation laser is sequentially transported to a plurality of optical fibers which in turn transport the laser light to separate individual remotely located laser fuel ignitors. The invention can be operated electro-optically with no need for any mechanical or moving parts, or, alternatively, can be operated electro-mechanically. The invention can be used to switch either pulsed or continuous wave laser light.

  12. Beyond the switch

    DEFF Research Database (Denmark)

    Aliakseyeu, Dzmitry; Meerbeek, Bernt; Mason, Jon

    2014-01-01

    The commercial introduction of connected lighting that can be integrated with sensors and other devices is opening up new possibilities in creating responsive and intelligent environments. The role of lighting in such systems goes beyond simply functional illumination. In part due to the large...... is to explore new ways of interacting with light where lighting can not only be switched on or off, but is an intelligent system embedded in the environment capable of creating a variety of effects. The connectivity between multiple systems and other ecosystems, for example when transitioning from your home...... and established lighting network, and with the advent of the LED, new types of lighting output are now possible. However, the current approach for controlling such systems is to simply replace the light switch with a somewhat more sophisticated smartphone-based remote control. The focus of this workshop...

  13. Laser activated superconducting switch

    International Nuclear Information System (INIS)

    Wolf, A.A.

    1976-01-01

    A superconducting switch or bistable device is described consisting of a superconductor in a cryogen maintaining a temperature just below the transition temperature, having a window of the proper optical frequency band for passing a laser beam which may impinge on the superconductor when desired. The frequency of the laser is equal to or greater than the optical absorption frequency of the superconducting material and is consistent with the ratio of the gap energy of the switch material to Planck's constant, to cause depairing of electrons, and thereby normalize the superconductor. Some embodiments comprise first and second superconducting metals. Other embodiments feature the two superconducting metals separated by a thin film insulator through which the superconducting electrons tunnel during superconductivity

  14. Coulomb Blockade Plasmonic Switch.

    Science.gov (United States)

    Xiang, Dao; Wu, Jian; Gordon, Reuven

    2017-04-12

    Tunnel resistance can be modulated with bias via the Coulomb blockade effect, which gives a highly nonlinear response current. Here we investigate the optical response of a metal-insulator-nanoparticle-insulator-metal structure and show switching of a plasmonic gap from insulator to conductor via Coulomb blockade. By introducing a sufficiently large charging energy in the tunnelling gap, the Coulomb blockade allows for a conductor (tunneling) to insulator (capacitor) transition. The tunnelling electrons can be delocalized over the nanocapacitor again when a high energy penalty is added with bias. We demonstrate that this has a huge impact on the plasmonic resonance of a 0.51 nm tunneling gap with ∼70% change in normalized optical loss. Because this structure has a tiny capacitance, there is potential to harness the effect for high-speed switching.

  15. Practical switching power supply design

    CERN Document Server

    Brown, Martin C

    1990-01-01

    Take the ""black magic"" out of switching power supplies with Practical Switching Power Supply Design! This is a comprehensive ""hands-on"" guide to the theory behind, and design of, PWM and resonant switching supplies. You'll find information on switching supply operation and selecting an appropriate topology for your application. There's extensive coverage of buck, boost, flyback, push-pull, half bridge, and full bridge regulator circuits. Special attention is given to semiconductors used in switching supplies. RFI/EMI reduction, grounding, testing, and safety standards are also deta

  16. Python Switch Statement

    Directory of Open Access Journals (Sweden)

    2008-06-01

    Full Text Available The Python programming language does not have a built in switch/case control structure as found in many other high level programming languages. It is thought by some that this is a deficiency in the language, and the control structure should be added. This paper demonstrates that not only is the control structure not needed, but that the methods available in Python are more expressive than built in case statements in other high level languages.

  17. Nanomechanics of flexoelectric switching

    Science.gov (United States)

    Očenášek, J.; Lu, H.; Bark, C. W.; Eom, C. B.; Alcalá, J.; Catalan, G.; Gruverman, A.

    2015-07-01

    We examine the phenomenon of flexoelectric switching of polarization in ultrathin films of barium titanate induced by a tip of an atomic force microscope (AFM). The spatial distribution of the tip-induced flexoelectricity is computationally modeled both for perpendicular mechanical load (point measurements) and for sliding load (scanning measurements), and compared with experiments. We find that (i) perpendicular load does not lead to stable ferroelectric switching in contrast to the load applied in the sliding contact load regime, due to nontrivial differences between the strain distributions in both regimes: ferroelectric switching for the perpendicular load mode is impaired by a strain gradient inversion layer immediately underneath the AFM tip; while for the sliding load regime, domain inversion is unimpaired within a greater material volume subjected to larger values of the mechanically induced electric field that includes the region behind the sliding tip; (ii) beyond a relatively small value of an applied force, increasing mechanical pressure does not increase the flexoelectric field inside the film, but results instead in a growing volume of the region subjected to such field that aids domain nucleation processes; and (iii) the flexoelectric coefficients of the films are of the order of few nC/m, which is much smaller than for bulk BaTi O3 ceramics, indicating that there is a "flexoelectric size effect" that mirrors the ferroelectric one.

  18. "Platform switching": Serendipity

    Directory of Open Access Journals (Sweden)

    N Kalavathy

    2014-01-01

    Full Text Available Implant dentistry is the latest developing field in terms of clinical techniques, research, material science and oral rehabilitation. Extensive work is being done to improve the designing of implants in order to achieve better esthetics and function. The main drawback with respect to implant restoration is achieving good osseointegration along with satisfactory stress distribution, which in turn will improve the prognosis of implant prosthesis by reducing the crestal bone loss. Many concepts have been developed with reference to surface coating of implants, surgical techniques for implant placement, immediate and delayed loading, platform switching concept, etc. This article has made an attempt to review the concept of platform switching was in fact revealed accidentally due to the nonavailability of the abutment appropriate to the size of the implant placed. A few aspect of platform switching, an upcoming idea to reduce crestal bone loss have been covered. The various methods used for locating and preparing the data were done through textbooks, Google search and related articles.

  19. Nanofluidic diode and bipolar transistor.

    Science.gov (United States)

    Daiguji, Hirofumi; Oka, Yukiko; Shirono, Katsuhiro

    2005-11-01

    Theoretical modeling of ionic distribution and transport in a nanochannel containing a surface charge on its wall, 30 nm high and 5 microm long, suggests that ionic current can be controlled by locally modifying the surface charge density through a gate electrode, even if the electrical double layers are not overlapped. When the surface charge densities at the right and left halves of a channel are the same absolute value but of different signs, this could form the basis of a nanofluidic diode. When the surface charge density at the middle part of a channel is modified, this could form the basis of a nanofluidic bipolar transistor.

  20. Fundamental transverse mode selection and self-stabilization in large optical cavity diode lasers under high injection current densities

    Science.gov (United States)

    Avrutin, Eugene A.; Ryvkin, Boris S.; Payusov, Alexey S.; Serin, Artem A.; Gordeev, Nikita Yu

    2015-11-01

    It is shown that in high-power, large optical cavity laser diodes at high injection currents, the optical losses due to nonuniform carrier accumulation in the optical confinement layer can ensure the laser operation in the fundamental transverse mode. An experimental demonstration of switching from second order mode to fundamental mode in large optical cavity lasers with current and/or temperature increase is reported and explained, with the calculated values for the switching current and temperature in good agreement with the measurements. The results experimentally prove the nonuniform nature of carrier accumulation in the confinement layer and may aid laser design for optimizing the output.

  1. All-Optical Flip-Flop Based on an SOA/DFB-Laser Diode Optical Feedback Scheme

    DEFF Research Database (Denmark)

    D'Oosterlinck, W.; Buron, Jakob Due; Öhman, Filip

    2007-01-01

    We report on the dynamic all-optical flip-flop (AOFF) operation of an optical feedback scheme consisting of a semiconductor optical amplifier (SOA) and a distributed feedback laser diode (DFB-LD), bidirectionally coupled to each other. The operation of the AOFF relies on the interplay between...... the optical powers in both the DFB-LD and the SOA. Switching times as low as 150ps for switch pulse energies of around 6 pJ and a repetition rate of 500MHz have been measured. The contrast ratio was measured to be above 12 dB....

  2. Laser diode package with enhanced cooling

    Science.gov (United States)

    Deri, Robert J [Pleasanton, CA; Kotovsky, Jack [Oakland, CA; Spadaccini, Christopher M [Oakland, CA

    2011-09-13

    A laser diode package assembly includes a reservoir filled with a fusible metal in close proximity to a laser diode. The fusible metal absorbs heat from the laser diode and undergoes a phase change from solid to liquid during the operation of the laser. The metal absorbs heat during the phase transition. Once the laser diode is turned off, the liquid metal cools off and resolidifies. The reservoir is designed such that that the liquid metal does not leave the reservoir even when in liquid state. The laser diode assembly further includes a lid with one or more fin structures that extend into the reservoir and are in contact with the metal in the reservoir.

  3. Stopping atoms with diode lasers

    International Nuclear Information System (INIS)

    Watts, R.N.; Wieman, C.E.

    1986-01-01

    The use of light pressure to cool and stop neutral atoms has been an area of considerable interest recently. Cooled neutral atoms are needed for a variety of interesting experiments involving neutral atom traps and ultrahigh-resolution spectroscopy. Laser cooling of sodium has previously been demonstrated using elegant but quite elaborate apparatus. These techniques employed stabilized dye lasers and a variety of additional sophisticated hardware. The authors have demonstrated that a frequency chirp technique can be implemented using inexpensive diode lasers and simple electronics. In this technique the atoms in an atomic beam scatter resonant photons from a counterpropagating laser beam. The momentum transfer from the photons slows the atoms. The primary difficulty is that as the atoms slow their Doppler shift changes, and so they are no longer in resonance with the incident photons. In the frequency chirp technique this is solved by rapidly changing the laser frequency so that the atoms remain in resonance. To achieve the necessary frequency sweep with a dye laser one must use an extremely sophisticated high-speed electrooptic modulator. With a diode laser, however, the frequency can be smoothly and rapidly varied over many gigahertz simply by changing the injection current

  4. Spectroscopic amplifier for pin diode

    International Nuclear Information System (INIS)

    Alonso M, M. S.; Hernandez D, V. M.; Vega C, H. R.

    2014-10-01

    The photodiode remains the basic choice for the photo-detection and is widely used in optical communications, medical diagnostics and field of corpuscular radiation. In detecting radiation it has been used for monitoring radon and its progeny and inexpensive spectrometric systems. The development of a spectroscopic amplifier for Pin diode is presented which has the following characteristics: canceler Pole-Zero (P/Z) with a time constant of 8 μs; constant gain of 57, suitable for the acquisition system; 4th integrator Gaussian order to waveform change of exponential input to semi-Gaussian output and finally a stage of baseline restorer which prevents Dc signal contribution to the next stage. The operational amplifier used is the TLE2074 of BiFET technology of Texas Instruments with 10 MHz bandwidth, 25 V/μs of slew rate and a noise floor of 17 nv/(Hz)1/2. The integrated circuit has 4 operational amplifiers and in is contained the total of spectroscopic amplifier that is the goal of electronic design. The results show like the exponential input signal is converted to semi-Gaussian, modifying only the amplitude according to the specifications in the design. The total system is formed by the detector, which is the Pin diode, a sensitive preamplifier to the load, the spectroscopic amplifier that is what is presented and finally a pulse height analyzer (Mca) which is where the spectrum is shown. (Author)

  5. Enhanced Stability and Controllability of an Ionic Diode Based on Funnel-Shaped Nanochannels with an Extended Critical Region.

    Science.gov (United States)

    Xiao, Kai; Xie, Ganhua; Zhang, Zhen; Kong, Xiang-Yu; Liu, Qian; Li, Pei; Wen, Liping; Jiang, Lei

    2016-05-01

    The enhanced stability and controllability of an ionic diode system based on funnel-shaped nanochannels with a much longer critical region is reported. The polarity of ion transport switching from anion/cation-selective to ambipolar can be controlled by tuning the length and charge of the critical region. This nanofluidic structure anticipates potential applications in single-molecule biosensing, water resource monitoring, and healthcare. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Safe LPV Controller Switching

    DEFF Research Database (Denmark)

    Trangbæk, K

    2011-01-01

    Before switching to a new controller it is crucial to assure that the new closed loop will be stable. In this paper it is demonstrated how stability can be checked with limited measurement data available from the current closed loop. The paper extends an existing method to linear parameter varying...... plants and controllers. Rather than relying on frequency domain methods as done in the LTI case, it is shown how to use standard LPV system identification methods. It is furthermore shown how to include model uncertainty to robustify the results. By appropriate filtering, it is only necessary to evaluate...

  7. Safe LPV Controller Switching

    DEFF Research Database (Denmark)

    Trangbæk, K

    2010-01-01

    Before switching to a new controller it is crucial to assure that the new closed loop will be stable. In this paper it is demonstrated how stability can be checked with limited measurement data available from the current closed loop. The paper extends an existing method to linear parameter varying...... plants and controllers. Rather than relying on frequency domain methods as done in the LTI case, it is shown how to use standard LPV system identification methods. By identifying a filtered closed-loop operator rather than directly identifying the plant, more reliable results are obtained....

  8. Frequency Stabilization of DFB Laser Diodes at 1572 nm for Spaceborne Lidar Measurements of CO2

    Science.gov (United States)

    Numata, Kenji; Chen, Jeffrey R.; Wu, Stewart T.; Abshire, James B.; Krainak, Michael A.

    2010-01-01

    We report a fiber-based, pulsed laser seeder system that rapidly switches among 6 wavelengths across atmospheric carbon dioxide (CO2) absorption line near 1572.3 nm for measurements of global CO2 mixing ratios to 1-ppmv precision. One master DFB laser diode has been frequency-locked to the CO2 line center using a frequency modulation technique, suppressing its peak-to-peak frequency drifts to 0.3 MHz at 0.8 sec averaging time over 72 hours. Four online DFB laser diodes have been offset-locked to the master laser using phase locked loops, with virtually the same sub-MHz absolute accuracy. The 6 lasers were externally modulated and then combined to produce the measurement pulse train.

  9. Neuromorphic atomic switch networks.

    Directory of Open Access Journals (Sweden)

    Audrius V Avizienis

    Full Text Available Efforts to emulate the formidable information processing capabilities of the brain through neuromorphic engineering have been bolstered by recent progress in the fabrication of nonlinear, nanoscale circuit elements that exhibit synapse-like operational characteristics. However, conventional fabrication techniques are unable to efficiently generate structures with the highly complex interconnectivity found in biological neuronal networks. Here we demonstrate the physical realization of a self-assembled neuromorphic device which implements basic concepts of systems neuroscience through a hardware-based platform comprised of over a billion interconnected atomic-switch inorganic synapses embedded in a complex network of silver nanowires. Observations of network activation and passive harmonic generation demonstrate a collective response to input stimulus in agreement with recent theoretical predictions. Further, emergent behaviors unique to the complex network of atomic switches and akin to brain function are observed, namely spatially distributed memory, recurrent dynamics and the activation of feedforward subnetworks. These devices display the functional characteristics required for implementing unconventional, biologically and neurally inspired computational methodologies in a synthetic experimental system.

  10. Modeling of rf MEMS switches

    Science.gov (United States)

    Robertson, Barbara; Ho, Fat D.; Hudson, Tracy D.

    2001-10-01

    The microelectromechanical system (MEMS) switch offers many benefits in radio frequency (RF) applications. These benefits include low insertion loss, high quality factor (Q), low power, RF isolation, and low cost. The ability to manufacture mechanical switches on a chip with electronics can lead to higher functionality, such as single-chip arrays, and smart switches. The MEMS switch is also used as a building block in devices such as phase shifters, filters, and switchable antenna elements. The MEMS designer needs models of these basic elements in order to incorporate them into their applications. The objective of this effort is to develop lumped element models for MEMS RF switches, which are incorporated into a CAD software. Tanner Research Inc.'s Electronic Design Automation (EDA) software is being used to develop a suite of mixed-signal RF switch models. The suite will include switches made from cantilever beams and fixed-fixed beams. The switches may be actuated by electrostatic, piezoelectric or electromagnetic forces. The effort presented in this paper concentrates on switches actuated by electrostatic forces. The lumped element models use a current-force electrical-mechanical analogy. Finite element modeling and device testing will be used to verify the Tanner models. The effects of materials, geometries, temperature, fringing fields, and mounting geometries are considered.

  11. Software Switching for Data Acquisition

    CERN Multimedia

    CERN. Geneva; Malone, David

    2016-01-01

    In this talk we discuss the feasibility of replacing telecom-class routers with a topology of commodity servers acting as software switches in data acquisition. We extend the popular software switch, Open vSwitch, with a dedicated, throughput-oriented buffering mechanism. We compare the performance under heavy many-to-one congestion to typical Ethernet switches and evaluate the scalability when building larger topologies, exploiting the integration with software-defined networking technologies. Please note that David Malone will speak on behalf of Grzegorz Jereczek.

  12. Recent developments in switching theory

    CERN Document Server

    Mukhopadhyay, Amar

    2013-01-01

    Electrical Science Series: Recent Developments in Switching Theory covers the progress in the study of the switching theory. The book discusses the simplified proof of Post's theorem on completeness of logic primitives; the role of feedback in combinational switching circuits; and the systematic procedure for the design of Lupanov decoding networks. The text also describes the classical results on counting theorems and their application to the classification of switching functions under different notions of equivalence, including linear and affine equivalences. The development of abstract har

  13. Checker Takes the Guesswork out of Diode Identification

    Science.gov (United States)

    Harman, Charles

    2011-01-01

    At technical colleges and secondary-level tech schools, students enrolled in basic electronics labs who have learned about diodes that do rectification are used to seeing power diodes like the 1N4001. When the students are introduced to low-power zener diodes and signal diodes, component identification gets more complex. If the small zeners are…

  14. Blue-emitting laser diodes

    Science.gov (United States)

    Nakano, K.; Ishibashi, A.

    This paper reviews the recent results of blue-emitting laser diodes. These devices are based on ZnMgSSe alloy II-VI semiconductors. Recently we have achieved room temperature continuous-wave operation of ZnMgSSe blue lasers for the first time. ZnMgSSe alloys offer a wide range of band-gap energy from 2.8 to 4.5 eV, while maintaining lattice matching to GaAs substrates. These characteristics make ZnMgSSe suitable for cladding layers of blue lasers. In this article, the feasibilities of ZnMgSSe will be reviewed. The laser structures and characteristics will be also mentioned.

  15. Phototherapy with Light Emitting Diodes

    Science.gov (United States)

    2018-01-01

    Within the field of dermatology, advances in the use of light emitting diodes (LEDs) have led to their clinical application for a variety of medical and cosmetic uses. Of note, one phototherapy device has demonstrated beneficial effects over a range of clinical applications (Omnilux™; GlobalMed Technologies, Glen Ellen, California). The study included a literature review of published studies. Using LEDs with frequencies of 415nm (blue), 633nm (red), and 830nm (infrared), this device has demonstrated significant results for the treatment of medical conditions, including mild-to-moderate acne vulgaris, wound healing, psoriasis, squamous cell carcinoma in situ (Bowen’s disease), basal cell carcinoma, actinic keratosis, and cosmetic applications. Although photodynamic therapy with the photosensitizer 5-aminolevulinic acid might cause stinging and burning, phototherapy is free of adverse events. We determined that phototherapy using LEDs is beneficial for a range of medical and aesthetic conditions encountered in the dermatology practice. This treatment displays an excellent safety profile.

  16. A Portable Diode Array Spectrophotometer.

    Science.gov (United States)

    Stephenson, David

    2016-05-01

    A cheap portable visible light spectrometer is presented. The spectrometer uses readily sourced items and could be constructed by anyone with a knowledge of electronics. The spectrometer covers the wavelength range 450-725 nm with a resolution better than 5 nm. The spectrometer uses a diffraction grating to separate wavelengths, which are detected using a 128-element diode array, the output of which is analyzed using a microprocessor. The spectrum is displayed on a small liquid crystal display screen and can be saved to a micro SD card for later analysis. Battery life (2 × AAA) is estimated to be 200 hours. The overall dimensions of the unit are 120 × 65 × 60 mm, and it weighs about 200 g. © The Author(s) 2016.

  17. Zinc oxide tetrapod nanocrystal diodes

    Science.gov (United States)

    Newton, Marcus Christian

    Advances in fabrication and analysis tools have allowed the synthesis and manipulation of functional materials with features comparable to fundamental physical length scales. Many interesting properties inherently due to quantum size effects have been observed in nanometre scale structures. It is hoped that these nanoscale structures will play a key role in future materials and devices that exploit their unique properties. Zinc oxide (ZnO) is a wide band-gap transparent and piezoelectric semiconductor material. It also has a large exciton binding energy which allows for stable ultraviolet light emission at room temperature. There are therefore foreseeable applications in optoelectronic devices which include ultraviolet photosensitive devices and light emitting diodes. Nanoscale structures formed from ZnO are interesting as they possess many of the properties inherent form the bulk but are also subject to various quantum size effects that may occur at the nanoscale. To date, the study of ZnO nanostructures is a relatively recent endeavour with the vast majority of reports being made within the last five years. ZnO is unique in that it forms a family of nanoscale structures. These structures include nanoscale wires, rods, hexagons, tetrapods, ribbons, rings, flowers and helixes. This work is focussed on the study of zinc oxide tetrapod crystalline nanoscale structures and their devices. We have synthesised ZnO tetrapods using chemical vapour transport techniques. Photoluminescence characterisation revealed the presence of optically active surface defects that could be quenched with a simple surface treatment. We have also for the first time observed resonant cavity modes in a single ZnO tetrapod nanocrystal. An ultraviolet sensitive Schottky diode was fabricated from a single ZnO tetrapod using focussed ion-beam assisted deposition techniques. The device characteristics observed were modelled and successfully shown to result from an illumination induced reduction in

  18. 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.

  19. Cern DD4424 ROM Diode Matrix

    CERN Multimedia

    A diode matrix is an extremely low-density form of read-only memory. It's one of the earliest forms of ROMs (dating back to the 1950s). Each bit in the ROM is represented by the presence or absence of one diode. The ROM is easily user-writable using a soldering iron and pair of wire cutters.This diode matrix board is a floppy disk boot ROM for a PDP-11, and consists of 32 16-bit words. When you access an address on the ROM, the circuit returns the represented data from that address.

  20. A Diode Matrix model M792

    CERN Multimedia

    A diode matrix is an extremely low-density form of read-only memory. It's one of the earliest forms of ROMs (dating back to the 1950s). Each bit in the ROM is represented by the presence or absence of one diode. The ROM is easily user-writable using a soldering iron and pair of wire cutters.This diode matrix board is a floppy disk boot ROM for a PDP-11, and consists of 32 16-bit words. When you access an address on the ROM, the circuit returns the represented data from that address.

  1. Single In x Ga1-x As nanowire/p-Si heterojunction based nano-rectifier diode

    Science.gov (United States)

    Sarkar, K.; Palit, M.; Guhathakurata, S.; Chattopadhyay, S.; Banerji, P.

    2017-09-01

    Nanoscale power supply units will be indispensable for fabricating next generation smart nanoelectronic integrated circuits. Fabrication of nanoscale rectifier circuits on a Si platform is required for integrating nanoelectronic devices with on-chip power supply units. In the present study, a nanorectifier diode based on a single standalone In x Ga1-x As nanowire/p-Si (111) heterojunction fabricated by metal organic chemical vapor deposition technique has been studied. The nanoheterojunction diodes have shown good rectification and fast switching characteristics. The rectification characteristics of the nanoheterojunction have been demonstrated by different standard waveforms of sinusoidal, square, sawtooth and triangular for two different frequencies of 1 and 0.1 Hz. Reverse recovery time of around 150 ms has been observed in all wave response. A half wave rectifier circuit with a simple capacitor filter has been assembled with this nanoheterojunction diode which provides 12% output efficiency. The transport of carriers through the heterojunction is investigated. The interface states density of the nanoheterojunction has also been determined. Occurrence of output waveforms incommensurate with the input is attributed to higher series resistance of the diode which is further explained considering the dimension of p-side and n-side of the junction. The sudden change of ideality factor after 1.7 V bias is attributed to recombination through interface states in space charge region. Low interface states density as well as high rectification ratio makes this heterojunction diode a promising candidate for future nanoscale electronics.

  2. Phenotypic switching in bacteria

    Science.gov (United States)

    Merrin, Jack

    Living matter is a non-equilibrium system in which many components work in parallel to perpetuate themselves through a fluctuating environment. Physiological states or functionalities revealed by a particular environment are called phenotypes. Transitions between phenotypes may occur either spontaneously or via interaction with the environment. Even in the same environment, genetically identical bacteria can exhibit different phenotypes of a continuous or discrete nature. In this thesis, we pursued three lines of investigation into discrete phenotypic heterogeneity in bacterial populations: the quantitative characterization of the so-called bacterial persistence, a theoretical model of phenotypic switching based on those measurements, and the design of artificial genetic networks which implement this model. Persistence is the phenotype of a subpopulation of bacteria with a reduced sensitivity to antibiotics. We developed a microfluidic apparatus, which allowed us to monitor the growth rates of individual cells while applying repeated cycles of antibiotic treatments. We were able to identify distinct phenotypes (normal and persistent) and characterize the stochastic transitions between them. We also found that phenotypic heterogeneity was present prior to any environmental cue such as antibiotic exposure. Motivated by the experiments with persisters, we formulated a theoretical model describing the dynamic behavior of several discrete phenotypes in a periodically varying environment. This theoretical framework allowed us to quantitatively predict the fitness of dynamic populations and to compare survival strategies according to environmental time-symmetries. These calculations suggested that persistence is a strategy used by bacterial populations to adapt to fluctuating environments. Knowledge of the phenotypic transition rates for persistence may provide statistical information about the typical environments of bacteria. We also describe a design of artificial

  3. Optical sectioning microscopes with no moving parts using a micro-stripe array light emitting diode.

    Science.gov (United States)

    Poher, V; Zhang, H X; Kennedy, G T; Griffin, C; Oddos, S; Gu, E; Elson, D S; Girkin, M; French, P M W; Dawson, M D; Neil, M A

    2007-09-03

    We describe an optical sectioning microscopy system with no moving parts based on a micro-structured stripe-array light emitting diode (LED). By projecting arbitrary line or grid patterns onto the object, we are able to implement a variety of optical sectioning microscopy techniques such as grid-projection structured illumination and line scanning confocal microscopy, switching from one imaging technique to another without modifying the microscope setup. The micro-structured LED and driver are detailed and depth discrimination capabilities are measured and calculated.

  4. X-ray radiation source based on a plasma filled diode

    International Nuclear Information System (INIS)

    Popkov, N.F.; Kargin, V.I.; Ryaslov, E.A.; Pikar, A.S.

    1996-01-01

    The results are given of studies on a plasma X-ray source providing 2.5 krad of radiation dose per pulse over an area of 100 cm 2 in the quantum energy range between 20 and 500 keV. The pulse duration was 100 ns. The spectral radiation distribution was obtained under various operating conditions of plasma and diode. A Marx generator served as the starting power source of 120 kJ with a discharge time of T/4=10 -6 s. A short electromagnetic pulse (10 -7 s) was shaped using plasma erosion opening switches. (author). 5 figs., 4 refs

  5. Hybrid switch for resonant power converters

    Science.gov (United States)

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  6. A pulsated weak-resonant-cavity laser diode with transient wavelength scanning and tracking for injection-locked RZ transmission.

    Science.gov (United States)

    Lin, Gong-Ru; Chi, Yu-Chieh; Liao, Yu-Sheng; Kuo, Hao-Chung; Liao, Zhi-Wang; Wang, Hai-Lin; Lin, Gong-Cheng

    2012-06-18

    By spectrally slicing a single longitudinal-mode from a master weak-resonant-cavity Fabry-Perot laser diode with transient wavelength scanning and tracking functions, the broadened self-injection-locking of a slave weak-resonant-cavity Fabry-Perot laser diode is demonstrated to achieve bi-directional transmission in a 200-GHz array-waveguide-grating channelized dense-wavelength-division-multiplexing passive optical network system. Both the down- and up-stream slave weak-resonant-cavity Fabry-Perot laser diodes are non-return-to-zero modulated below threshold and coherently injection-locked to deliver the pulsed carrier for 25-km bi-directional 2.5 Gbits/s return-to-zero transmission. The master weak-resonant-cavity Fabry-Perot laser diode is gain-switched at near threshold condition and delivers an optical coherent pulse-train with its mode linewidth broadened from 0.2 to 0.8 nm by transient wavelength scanning, which facilitates the broadband injection-locking of the slave weak-resonant-cavity Fabry-Perot laser diodes with a threshold current reducing by 10 mA. Such a transient wavelength scanning induced spectral broadening greatly releases the limitation on wavelength injection-locking range required for the slave weak-resonant-cavity Fabry-Perot laser diode. The theoretical modeling and numerical simulation on the wavelength scanning and tracking effects of the master and slave weak-resonant-cavity Fabry-Perot laser diodes are performed. The receiving power sensitivity for back-to-back transmission at bit-error-rate transmission is less than 2 dB for all 16 channels.

  7. A Radical Switch

    Directory of Open Access Journals (Sweden)

    Alexander Rappaport

    2017-09-01

    Full Text Available Architecture is the most vulnerable part of culture, almost doomed to destruction of its fundamentals, while the rise of its intellectual and creative level is badly needed. However, neither the resort to postmarxist French philosophy nor bringing the results of development of science and technology into architecture, neither computerization nor peculiarities of parametricism and deconstructivism are helpful. It can be stated that in the beginning of the third millennium architecture and architectural education are in stalemate. The way out is in a “radical” switch from comprehension of object space to the time and to the processes of thinking, designing and historical change in professional mentality. The interests must be focused not on the object, but on the process enabling the use of return reflexive strokes as well.

  8. Battery switch for downhole tools

    Science.gov (United States)

    Boling, Brian E.

    2010-02-23

    An electrical circuit for a downhole tool may include a battery, a load electrically connected to the battery, and at least one switch electrically connected in series with the battery and to the load. The at least one switch may be configured to close when a tool temperature exceeds a selected temperature.

  9. Improved switch-resistor packaging

    Science.gov (United States)

    Redmerski, R. E.

    1980-01-01

    Packaging approach makes resistors more accessible and easily identified with specific switches. Failures are repaired more quickly because of improved accessibility. Typical board includes one resistor that acts as circuit breaker, and others are positioned so that their values can be easily measured when switch is operated. Approach saves weight by using less wire and saves valuable panel space.

  10. Task Switching: A PDP Model

    Science.gov (United States)

    Gilbert, Sam J.; Shallice, Tim

    2002-01-01

    When subjects switch between a pair of stimulus-response tasks, reaction time is slower on trial N if a different task was performed on trial N--1. We present a parallel distributed processing (PDP) model that simulates this effect when subjects switch between word reading and color naming in response to Stroop stimuli. Reaction time on "switch…

  11. A CMOS Switched Transconductor Mixer

    NARCIS (Netherlands)

    Klumperink, Eric A.M.; Louwsma, S.M.; Wienk, Gerhardus J.M.; Nauta, Bram

    A new CMOS active mixer topology can operate at low supply voltages by the use of switches exclusively connected to the supply voltages. Such switches require less voltage headroom and avoid gate-oxide reliability problems. Mixing is achieved by exploiting two transconductors with cross-coupled

  12. Amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-04-01

    Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

  13. Diode Laser Ear Piercing: A Novel Technique.

    Science.gov (United States)

    Suseela, Bibilash Babu; Babu, Preethitha; Chittoria, Ravi Kumar; Mohapatra, Devi Prasad

    2016-01-01

    Earlobe piercing is a common office room procedure done by a plastic surgeon. Various methods of ear piercing have been described. In this article, we describe a novel method of laser ear piercing using the diode laser. An 18-year-old female patient underwent an ear piercing using a diode laser with a power of 2.0 W in continuous mode after topical local anaesthetic and pre-cooling. The diode laser was fast, safe, easy to use and highly effective way of ear piercing. The advantages we noticed while using the diode laser over conventional methods were more precision, minimal trauma with less chances of hypertrophy and keloids, no bleeding with coagulation effect of laser, less time taken compared to conventional method and less chance of infection due to thermal heat effect of laser.

  14. NAMMA DIODE LASER HYGROMETER (DLH) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Diode Laser Hygrometer (DLH), a near-infrared spectrometer operating from aircraft platforms, was developed by NASA's Langley and Ames Research Centers. It...

  15. NAMMA DIODE LASER HYGROMETER (DLH) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA Diode Laser Hygrometer (DLH) dataset uses the DLH, a near-infrared spectrometer operating from aircraft platforms, was developed by NASA's Langley and Ames...

  16. Low-Loss, High-Isolation Microwave Microelectromechanical Systems (MEMS) Switches Being Developed

    Science.gov (United States)

    Ponchak, George E.

    2002-01-01

    Switches, electrical components that either permit or prevent the flow of electricity, are the most important and widely used electrical devices in integrated circuits. In microwave systems, switches are required for switching between the transmitter and receiver; in communication systems, they are needed for phase shifters in phased-array antennas, for radar and communication systems, and for the new class of digital or software definable radios. Ideally, switches would be lossless devices that did not depend on the electrical signal's frequency or power, and they would not consume electrical power to change from OFF to ON or to maintain one of these two states. Reality is quite different, especially at microwave frequencies. Typical switches in microwave integrated circuits are pin diodes or gallium arsenide (GaAs) field-effect transistors that are nonlinear, with characteristics that depend on the power of the signal. In addition, they are frequency-dependent, lossy, and require electrical power to maintain a certain state. A new type of component has been developed that overcomes most of these technical difficulties. Microelectromechanical (MEMS) switches rely on mechanical movement as a response to an applied electrical force to either transmit or reflect electrical signal power. The NASA Glenn Research Center has been actively developing MEMS for microwave applications for over the last 5 years. Complete fabrication procedures have been developed so that the moving parts of the switch can be released with near 100-percent yield. Moreover, the switches fabricated at Glenn have demonstrated state-of-the-art performance. A typical MEMS switch is shown. The switch extends over the signal and ground lines of a finite ground coplanar waveguide, a commonly used microwave transmission line. In the state shown, the switch is in the UP state and all the microwave power traveling along the transmission line proceeds unimpeded. When a potential difference is applied

  17. Programmable diode/resistor-like behavior of nanostructured vanadium pentoxide xerogel thin film.

    Science.gov (United States)

    Wan, Zhenni; Darling, Robert B; Anantram, M P

    2015-11-11

    Electrical properties of a Cr/V2O5/Cr structure are investigated and switching of the device due to electrochemical reactions is observed at low bias (resistor (reverse sweep first). The switching is irreversible and persistent, lasting for more than one month. By performing environmental tests, we prove that water molecules in the atmosphere and intercalated in the xerogel film are involved in the electrochemical reactions. It is proposed that an interfacial layer with reduced oxidation state forms at the Cr/V2O5 interface, and creates a higher Schottky barrier due to rise of electron affinity. Different interfacial layer thicknesses in forward and reverse first sweeps are responsible for different I-V characteristics in subsequent sweeps. The results suggest future applications of these V2O5 thin films in low-power read-only memory devices and diode-resistor networks.

  18. Bypass diode for a solar cell

    Science.gov (United States)

    Rim, Seung Bum [Palo Alto, CA; Kim, Taeseok [San Jose, CA; Smith, David D [Campbell, CA; Cousins, Peter J [Menlo Park, CA

    2012-03-13

    Bypass diodes for solar cells are described. In one embodiment, a bypass diode for a solar cell includes a substrate of the solar cell. A first conductive region is disposed above the substrate, the first conductive region of a first conductivity type. A second conductive region is disposed on the first conductive region, the second conductive region of a second conductivity type opposite the first conductivity type.

  19. Phase-change radiative thermal diode

    OpenAIRE

    Ben-Abdallah, Philippe; Biehs, Svend-Age

    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 ap...

  20. Switching Phenomena in a System with No Switches

    Science.gov (United States)

    Preis, Tobias; Stanley, H. Eugene

    2010-02-01

    It is widely believed that switching phenomena require switches, but this is actually not true. For an intriguing variety of switching phenomena in nature, the underlying complex system abruptly changes from one state to another in a highly discontinuous fashion. For example, financial market fluctuations are characterized by many abrupt switchings creating increasing trends ("bubble formation") and decreasing trends ("financial collapse"). Such switching occurs on time scales ranging from macroscopic bubbles persisting for hundreds of days to microscopic bubbles persisting only for a few seconds. We analyze a database containing 13,991,275 German DAX Future transactions recorded with a time resolution of 10 msec. For comparison, a database providing 2,592,531 of all S&P500 daily closing prices is used. We ask whether these ubiquitous switching phenomena have quantifiable features independent of the time horizon studied. We find striking scale-free behavior of the volatility after each switching occurs. We interpret our findings as being consistent with time-dependent collective behavior of financial market participants. We test the possible universality of our result by performing a parallel analysis of fluctuations in transaction volume and time intervals between trades. We show that these financial market switching processes have properties similar to those of phase transitions. We suggest that the well-known catastrophic bubbles that occur on large time scales—such as the most recent financial crisis—are no outliers but single dramatic representatives caused by the switching between upward and downward trends on time scales varying over nine orders of magnitude from very large (≈102 days) down to very small (≈10 ms).

  1. Model Reduction of Switched Systems Based on Switching Generalized Gramians

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Wisniewski, Rafal

    2012-01-01

    In this paper, a general method for model order reduction of discrete-time switched linear systems is presented. The proposed technique uses switching generalized gramians. It is shown that several classical reduction methods can be developed into the generalized gramian framework for the model...... reduction of linear systems and for the reduction of switched systems. Discrete-time balanced reduction within a specified frequency interval is taken as an example within this framework. To avoid numerical instability and to increase the numerical efficiency, a generalized gramian-based Petrov...

  2. Cr:ZnS saturable absorber passively Q-switched mode-locking Tm,Ho:LLF laser.

    Science.gov (United States)

    Zhang, Xinlu; Luo, Yong; Wang, Tianhan; Dai, Junfeng; Zhang, Jianxin; Li, Jiang; Cui, Jinhui; Huang, Jinjer

    2017-04-10

    We first report on a diode-end-pumped passively Q-switched mode-locking Tm,Ho:LLF laser at 2053 nm by using a Cr:ZnS saturable absorber. A stable Q-switched mode-locking pulse train with a nearly 100% modulation depth was achieved. The repetition frequency of the Q-switched pulse envelope increased from 0.5 to 12.3 kHz with increasing pump power from 1 to 4.36 W. The maximum average output power of 145 mW was obtained, and the width of the mode-locked pulse was estimated to be less than 682 ps with a 250 MHz repetition frequency within a Q-switched pulse envelope of about 700 ns.

  3. A 380 V High Efficiency and High Power Density Switched-Capacitor Power Converter using Wide Band Gap Semiconductors

    DEFF Research Database (Denmark)

    Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger

    2018-01-01

    . This paper presents such a high voltage low power switched-capacitor DC-DC converter with an input voltage upto 380 V (compatible with rectified European mains) and an output power experimentally validated up to 21.3 W. The wideband gap semiconductor devices of GaN switches and SiC diodes are combined......State-of-the-art switched-capacitor DC-DC power converters mainly focus on low voltage and/or high power applications. However, at high voltage and low power levels, new designs are anticipated to emerge and a power converter that has both high efficiency and high power density is highly desirable...... to compose the proposed power stage. Their switching and loss characteristics are analyzed with transient waveforms and thermal images. Different isolated driving circuits are compared and a compact isolated halfbridge driving circuit is proposed. The full-load efficiencies of 98.3% and 97.6% are achieved...

  4. A 380 V High Efficiency and High Power Density Switched-Capacitor Power Converter using Wide Band Gap Semiconductors

    DEFF Research Database (Denmark)

    Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger

    2018-01-01

    State-of-the-art switched-capacitor DC-DC power converters mainly focus on low voltage and/or high power applications. However, at high voltage and low power levels, new designs are anticipated to emerge and a power converter that has both high efficiency and high power density is highly desirable....... This paper presents such a high voltage low power switched-capacitor DC-DC converter with an input voltage upto 380 V (compatible with rectified European mains) and an output power experimentally validated up to 21.3 W. The wideband gap semiconductor devices of GaN switches and SiC diodes are combined...... to compose the proposed power stage. Their switching and loss characteristics are analyzed with transient waveforms and thermal images. Different isolated driving circuits are compared and a compact isolated halfbridge driving circuit is proposed. The full-load efficiencies of 98.3% and 97.6% are achieved...

  5. Performance of the cold powered diodes and diode leads in the main magnets of the LHC

    CERN Document Server

    Willering, G P; Bajko, M; Bednarek, M; Bottura, L; Charifoulline, Z; Dahlerup-Petersen, K; Dib, G; D'Angelo, G; Gharib, A; Grand-Clement, L; Izquierdo Bermudez, S; Prin, H; Roger, V; Rowan, S; Savary, F; Tock, J-Ph; Verweij, A

    2015-01-01

    During quench tests in 2011 variations in resistance of an order of magnitude were found in the diode by-pass circuit of the main LHC magnets. An investigation campaign was started to understand the source, the occurrence and the impact of the high resistances. Many tests were performed offline in the SM18 test facility with a focus on the contact resistance of the diode to heat sink contact and the diode wafer temperature. In 2014 the performance of the diodes and diode leads of the main dipole bypass systems in the LHC was assessed during a high current qualification test. In the test a current cycle similar to a magnet circuit discharge from 11 kA with a time constant of 100 s was performed. Resistances of up to 600 μΩ have been found in the diode leads at intermediate current, but in general the high resistances decrease at higher current levels and no sign of overheating of diodes has been seen and the bypass circuit passed the test. In this report the performance of the diodes and in particular the co...

  6. DETERMINANT OF DOWNWARD AUDITOR SWITCHING

    Directory of Open Access Journals (Sweden)

    Totok Budisantoso

    2017-12-01

    Full Text Available Abstract: Determinant of Downward Auditor Switching. This study examines the factors that influence downward auditor switching in five ASEAN countries. Fixed effect logistic regression was used as analytical method. This study found that opinion shopping occurred in ASEAN, especially in distress companies. Companies with complex businesses will retain the Big Four auditors to reduce complexity and audit costs. Audit and public committees serve as guardians of auditor quality. On the other hand, shareholders failed to maintain audit quality. It indicates that there is entrenchment effect in auditor switching.

  7. Bipolar resistive switching based on bis(8-hydroxyquinoline) cadmium complex: Mechanism and non-volatile memory application

    International Nuclear Information System (INIS)

    Wang Ying; Yang Ting; Xie Ji-Peng; Lü Wen-Li; Fan Guo-Ying; Liu Su

    2013-01-01

    Stable and persistent bipolar resistive switching was observed in an organic diode with the structure of indium-tin oxide (ITO)/bis(8-hydroxyquinoline) cadmium (Cdq 2 )/Al. Aggregate formation and electric field driven trapping and de-trapping of charge carriers in the aggregate states that lie in the energy gap of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the organic molecule were proposed as the mechanism of the observed bipolar resistive switching, and this was solidly supported by the results of AFM investigations. Repeatedly set, read, and reset measurements demonstrated that the device is potentially applicable in non-volatile memories

  8. Design of 5 V DC to 20 V DC switching regulator for power supply module

    Science.gov (United States)

    Azmi, N. A.; Murad, S. A. Z.; Harun, A.; Ismail, R. C.; Isa, M. N. M.; Zulkifeli, M. A.

    2017-09-01

    This paper presents the design of 5 V to 20 V DC switching regulator for power supply module. A voltage multiplier which consists of cascaded diode-capacitor combination is used in order to obtain a high voltage power supply. Due to power loss that has occurred in a stray of component arrangement, the proposed design employs a pulse width modulation (PWM) controller circuit with an inclusion of a capacitor, diode, and inductor components. The input supply of 5 V DC to LT1618 controller circuit has produced 20.35 V based from simulation results. Meanwhile, the measurement results of 19.36 V are obtained and the feedback signal is required for the purpose of stabilizing the output. The proposed design can reduce the components as well as the PCB size, thus minimizing the overall cost of making a switching regulator for power supply module.

  9. Solid state bistable power switch

    Science.gov (United States)

    Bartko, J.; Shulman, H.

    1970-01-01

    Tin and copper provide high current and switching time capabilities for high-current resettable fuses. They show the best performance for trip current and degree of reliability, and have low coefficients of thermal expansion.

  10. Electron collisions in gas switches

    International Nuclear Information System (INIS)

    Christophorou, L.G.

    1989-01-01

    Many technologies rely on the conduction/insulation properties of gaseous matter for their successful operation. Many others (e.g., pulsed power technologies) rely on the rapid change (switching or modulation) of the properties of gaseous matter from an insulator to a conductor and vice versa. Studies of electron collision processes in gases aided the development of pulsed power gas switches, and in this paper we shall briefly illustrate the kind of knowledge on electron collision processes which is needed to optimize the performance of such switching devices. To this end, we shall refer to three types of gas switches: spark gap closing, self-sustained diffuse discharge closing, and externally-sustained diffuse discharge opening. 24 refs., 15 figs., 2 tabs

  11. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [State Univ. of New York (SUNY), Plattsburgh, NY (United States); Univ. of California, Davis, CA (United States)

    2012-01-20

    Photoconductive semiconductor switches (PCSS) have been investigated since the late 1970s. Some devices have been developed that withstand tens of kilovolts and others that switch hundreds of amperes. However, no single device has been developed that can reliably withstand both high voltage and switch high current. Yet, photoconductive switches still hold the promise of reliable high voltage and high current operation with subnanosecond risetimes. Particularly since good quality, bulk, single crystal, wide bandgap semiconductor materials have recently become available. In this chapter we will review the basic operation of PCSS devices, status of PCSS devices and properties of the wide bandgap semiconductors 4H-SiC, 6H-SiC and 2H-GaN.

  12. Tunneling Electroresistance Effect with Diode Characteristic for Cross-Point Memory.

    Science.gov (United States)

    Lee, Hong-Sub; Park, Hyung-Ho

    2016-06-22

    Cross-point memory architecture (CPMA) by using memristors has attracted considerable attention because of its high-density integration. However, a common and significant drawback of the CPMA is related to crosstalk issues between cells by sneak currents. This study demonstrated the sneak current free resistive switching characteristic of a ferroelectric tunnel diode (FTD) memristor for a CPMA by utilizing a novel concept of a ferroelectric quadrangle and triangle barrier switch. A FTD of Au/BaTiO3 (5 nm)/Nb-doped SrTiO3 (100) was used to obtain a desirable memristive effect for the CPMA. The FTD could reversibly change the shape of the ferroelectric potential from a quadrangle to a triangle. The effect included high nonlinearity and diode characteristics. It was derived from utilizing different sequences of carrier transport mechanisms such as the direct tunneling current, Fowler-Nordheim tunneling, and thermionic emission. The FTD memristor demonstrated the feasibility of sneak current-free high-density CPMA.

  13. High repetition rate, high peak power, diode pumped Tm:YLF laser

    Science.gov (United States)

    Jabczynski, J. K.; Gorajek, Ł.; Zendzian, W.; Kwiatkowski, J.; Jelínková, H.; Šulc, J.; Němec, M.

    2009-02-01

    The room-temperature, water-cooled, diode pumped Tm:YLF laser head was elaborated and examined. For pumping the fiber coupled (0.2 mm core diameter) 25-W laser diode bar emitting at 792-nm wavelength was deployed. Near 5 W of CW output power and 25% slope efficiency was demonstrated in a short, 70-mm long resonator. Tuning in 1845-1935 nm wavelength range by means of 2-plate Lyot filter was demonstrated only in free-running regime. The fused silica acousto-optic modulator with above 80% diffraction efficiency for 25-W power of RF was deployed as the Q-switch for such a laser. In the best case of Q-switching regime, up to 10-mJ output energy with 47-ns pulse duration, 220 kW peak power was demonstrated for 133 Hz. For higher repetition rate of 2 kHz, 12 kW peak power with 2.5 W of average power was achieved.

  14. A Piezoelectric Cryogenic Heat Switch

    Science.gov (United States)

    Jahromi, Amir E.; Sullivan, Dan F.

    2014-01-01

    We have measured the thermal conductance of a mechanical heat switch actuated by a piezoelectric positioner, the PZHS (PieZo electric Heat Switch), at cryogenic temperatures. The thermal conductance of the PZHS was measured between 4 K and 10 K, and on/off conductance ratios greater than 100 were achieved when the positioner applied its maximum force of 8 N. We discuss the advantages of using this system in cryogenic applications, and estimate the ultimate performance of an optimized PZHS.

  15. A PIN diode controlled dual-tuned MRI RF coil and phased array for multi nuclear imaging.

    Science.gov (United States)

    Ha, Seunghoon; Hamamura, Mark J; Nalcioglu, Orhan; Muftuler, L Tugan

    2010-05-07

    MR imaging of nuclei other than hydrogen has been used to investigate metabolism in humans and animals. However, MRI observable nuclei other than hydrogen are not as abundant and as a result the image SNR is lower. Dual-tuned radio frequency (RF) coils are developed for these studies in which high-resolution structural images are acquired using hydrogen and metabolic information is acquired by exciting the other nucleus. Using a dual-tuned coil, the experimenter avoids the inconvenience of moving the patient out and replacing the RF coil for imaging different nuclei. This also eliminates image registration problems. However, the common scheme of using trap circuits for dual-tuned operation results in increased coil losses as well as problems in obtaining optimal tuning and matching at both frequencies. Here, a new approach is presented using PIN diodes to switch the coil between two resonance frequencies. This design eliminates the need for the trap circuit and associated losses from the self-resistance of the trap circuit inductors. At the operating frequencies we used, the equivalent series resistance of an inductor is higher than that of the PIN diodes. In order to test the efficacy of this new approach, we first built two surface coils of identical geometry, one with the conventional trap circuits and one with the PIN diode switches. We also studied the performances of both coils when the coils are divided into shorter conductors segments by adding more tuning elements. It is known that dividing the coil into shorter conductor segments helps reduce radiation and electric field losses. We explored this effect for both coils at both operating frequencies. Finally, a dual-tuned receive-only phased array was designed and built with the PIN diode circuit to switch between two resonance frequencies. A conventional dual-tuned birdcage coil was designed and built to transmit RF power. A unique feature of this coil is that the RF power is fed through two separate sets

  16. Chromatic interocular-switch rivalry

    Science.gov (United States)

    Christiansen, Jens H.; D'Antona, Anthony D.; Shevell, Steven K.

    2017-01-01

    Interocular-switch rivalry (also known as stimulus rivalry) is a kind of binocular rivalry in which two rivalrous images are swapped between the eyes several times a second. The result is stable periods of one image and then the other, with stable intervals that span many eye swaps (Logothetis, Leopold, & Sheinberg, 1996). Previous work used this close kin of binocular rivalry with rivalrous forms. Experiments here test whether chromatic interocular-switch rivalry, in which the swapped stimuli differ in only chromaticity, results in slow alternation between two colors. Swapping equiluminant rivalrous chromaticities at 3.75 Hz resulted in slow perceptual color alternation, with one or the other color often continuously visible for two seconds or longer (during which there were 15+ eye swaps). A well-known theory for sustained percepts from interocular-switch rivalry with form is inhibitory competition between binocular neurons driven by monocular neurons with matched orientation tuning in each eye; such binocular neurons would produce a stable response when a given orientation is swapped between the eyes. A similar model can account for the percepts here from chromatic interocular-switch rivalry and is underpinned by the neurophysiological finding that color-preferring binocular neurons are driven by monocular neurons from each eye with well-matched chromatic selectivity (Peirce, Solomon, Forte, & Lennie, 2008). In contrast to chromatic interocular-switch rivalry, luminance interocular-switch rivalry with swapped stimuli that differ in only luminance did not result in slowly alternating percepts of different brightnesses. PMID:28510624

  17. Next generation diode lasers with enhanced brightness

    Science.gov (United States)

    Ried, S.; Rauch, S.; Irmler, L.; Rikels, J.; Killi, A.; Papastathopoulos, E.; Sarailou, E.; Zimer, H.

    2018-02-01

    High-power diode lasers are nowadays well established manufacturing tools in high power materials processing, mainly for tactile welding, surface treatment and cladding applications. Typical beam parameter products (BPP) of such lasers range from 30 to 50 mm·mrad at several kilowatts of output power. TRUMPF offers a product line of diode lasers to its customers ranging from 150 W up to 6 kW of output power. These diode lasers combine high reliability with small footprint and high efficiency. However, up to now these lasers are limited in brightness due to the commonly used spatial and coarse spectral beam combining techniques. Recently diode lasers with enhanced brightness have been presented by use of dense wavelength multiplexing (DWM). In this paper we report on TRUMPF's diode lasers utilizing DWM. We demonstrate a 2 kW and a 4 kW system ideally suited for fine welding and scanner welding applications. The typical laser efficiency is in the range of 50%. The system offers plug and play exchange of the fiber beam delivery cable, multiple optical outputs and integrated cooling in a very compact package. An advanced control system offers flexible integration in any customer's shop floor environment and includes industry 4.0 capabilities (e.g. condition monitoring and predictive maintenance).

  18. Magnetic-fluid-based smart centrifugal switch

    CERN Document Server

    Bhatt, R P

    2002-01-01

    A new type of centrifugal switch, which we call 'smart centrifugal switch' is designed and developed utilizing the novel properties of magnetic fluid. No mechanical movement is involved in the sensing and switching operations of this centrifugal switch and both these operations are achieved in a smart way. The performance of the switch is studied. This switch has several important advantages over conventional centrifugal switches like smart and non-contact type operation, sparkless and hence explosion proof working and inertia-less simple structure.

  19. Fluctuation-induced switching and the switching path distribution.

    Science.gov (United States)

    Dykman, Mark

    2009-03-01

    Fluctuation-induced switching is at the root of diverse phenomena currently studied in Josephson junctions, nano-mechanical systems, nano-magnets, and optically trapped atoms. In a fluctuation leading to switching the system must overcome an effective barrier, making switching events rare, for low fluctuation intensity. We will provide an overview of the methods of finding the switching barrier for systems away from thermal equilibrium. Generic features of the barrier, such as scaling with the system parameters, will be discussed. We will also discuss the motion of the system in switching and the ways of controlling it. Two major classes of systems will be considered: dynamical systems, where fluctuations are induced by noise, and birth-death systems. Even though the motion during switching is random, the paths followed in switching form a narrow tube in phase space of the system centered at the most probable path. The paths distribution is generally Gaussian and has specific features, which have been seen in the experiment [1]. Finding the most probable path itself can be reduced to solving a problem of Hamiltonian dynamics of an auxiliary noise-free system. The solution also gives the switching barrier. The barrier can be found explicitly close to parameter values where the number of stable states of the system changes and the dynamics is controlled by a slow variable. The scaling of the barrier height depends on the type of the corresponding bifurcation. We show that, both for birth-death and for Gaussian noise driven systems, the presence of even weak non-Gaussian noise can strongly modify the switching rate. The effect is described in a simple explicit form [2,3]. Weak deviations of the noise statistics from Gaussian can be sensitively detected using balanced dynamical bridge, where this deviation makes the populations of coexisting stable states different from each other; a realization of such a bridge will be discussed. We will also discuss the sharp

  20. Light emitting diodes as a plant lighting source

    Energy Technology Data Exchange (ETDEWEB)

    Bula, R.J.; Tennessen, D.J.; Morrow, R.C. [Wisconsin Center for Space Automation and Robotics, Madison, WI (United States); Tibbitts, T.W. [Univ. of Wisconsin, Madison, WI (United States)

    1994-12-31

    Electroluminescence in solid materials is defined as the generation of light by the passage of an electric current through a body of solid material under an applied electric field. A specific type of electroluminescence, first noted by Lossew in 1923, involves the generation of photons when electrons are passed through a p-n junction of certain solid materials (junction of a n-type semiconductor, an electron donor, and a p-type semiconductor, an electron acceptor). Development efforts to translate these observations into visible light emitting devices, however, was not undertaken until the 1950s. The term, light emitting diode (LEDs), was first used in a report by Wolfe, et al., in 1955. The development of this light emitting semiconductor technology dates back less than 30 years. During this period of time, the LED has evolved from a rare and expensive light generating device to one of the most widely used electronic components. The most popular applications of the LED are as indicators or as optoelectronic switches. However, several recent advances in LED technology have made possible the utilization of LEDs for applications that require a high photon flux, such as for plant lighting in controlled environments. The new generation of LEDs based on a gallium aluminum arsenide (GaAlAS) semiconductor material fabricated as a double heterostructure on a transparent substrate has opened up many new applications for these LEDs.

  1. Stirling-Cycle Cooling For Tunable Diode Laser

    Science.gov (United States)

    Durso, Santo S.; May, Randy D.; Tuchscherer, Matthew A.; Webster, Christopher R.

    1991-01-01

    Miniature Stirling-cycle cooler effective in continously cooling PbSnTe tunable diode laser to stable operating temperature near 80 K. Simplifies laboratory diode-laser spectroscopy and instruments for use aboard aircraft and balloons.

  2. Diode-side-pumped Alexandrite slab lasers.

    Science.gov (United States)

    Damzen, M J; Thomas, G M; Minassian, A

    2017-05-15

    We present the investigation of diode-side-pumping of Alexandrite slab lasers in a range of designs using linear cavity and grazing-incidence bounce cavity configurations. An Alexandrite slab laser cavity with double-pass side pumping produces 23.4 mJ free-running energy at 100 Hz rate with slope efficiency ~40% with respect to absorbed pump energy. In a slab laser with single-bounce geometry output power of 12.2 W is produced, and in a double-bounce configuration 6.5 W multimode and 4.5 W output in TEM 00 mode is produced. These first results of slab laser and amplifier designs in this paper highlight some of the potential strategies for power and energy scaling of Alexandrite using diode-side-pumped Alexandrite slab architectures with future availability of higher power red diode pumping.

  3. Laser scanning laser diode photoacoustic microscopy system.

    Science.gov (United States)

    Erfanzadeh, Mohsen; Kumavor, Patrick D; Zhu, Quing

    2018-03-01

    The development of low-cost and fast photoacoustic microscopy systems enhances the clinical applicability of photoacoustic imaging systems. To this end, we present a laser scanning laser diode-based photoacoustic microscopy system. In this system, a 905 nm, 325 W maximum output peak power pulsed laser diode with 50 ns pulsewidth is utilized as the light source. A combination of aspheric and cylindrical lenses is used for collimation of the laser diode beam. Two galvanometer scanning mirrors steer the beam across a focusing aspheric lens. The lateral resolution of the system was measured to be ∼21 μm using edge spread function estimation. No averaging was performed during data acquisition. The imaging speed is ∼370 A-lines per second. Photoacoustic microscopy images of human hairs, ex vivo mouse ear, and ex vivo porcine ovary are presented to demonstrate the feasibility and potentials of the proposed system.

  4. High efficiency and broadband acoustic diodes

    Science.gov (United States)

    Fu, Congyi; Wang, Bohan; Zhao, Tianfei; Chen, C. Q.

    2018-01-01

    Energy transmission efficiency and working bandwidth are the two major factors limiting the application of current acoustic diodes (ADs). This letter presents a design of high efficiency and broadband acoustic diodes composed of a nonlinear frequency converter and a linear wave filter. The converter consists of two masses connected by a bilinear spring with asymmetric tension and compression stiffness. The wave filter is a linear mass-spring lattice (sonic crystal). Both numerical simulation and experiment show that the energy transmission efficiency of the acoustic diode can be improved by as much as two orders of magnitude, reaching about 61%. Moreover, the primary working band width of the AD is about two times of the cut-off frequency of the sonic crystal filter. The cut-off frequency dependent working band of the AD implies that the developed AD can be scaled up or down from macro-scale to micro- and nano-scale.

  5. Self-magnetically insulated ion diode

    International Nuclear Information System (INIS)

    VanDevender, J.; Quintenz, J.; Leeper, R.; Johnson, D.; Crow, J.

    1981-01-01

    Light ion diodes for producing 1--100 TW ion beams are required for inertial confinement fusion. The theory, numerical simulations, and experiments on a self-magnetically insulated ion diode are presented. The treatment is from the point of view of a self-magnetically insulated transmission line with an ion loss current and differs from the usual treatment of the pinched electron beam diode. The simulations show that the ratio V/IZ 0 =0.25 in such a structure with voltage V, local total current I, and local vacuum wave impedance Z 0 . The ion current density is enhanced by a factor of approximately 2 over the simple space-charge limited value. The simulation results are verified in an experiment. An analytical theory is then presented for scaling the results to produce a focused beam of protons with a power of up to 10 13 W

  6. Ultrafast photoconductor detector-laser-diode transmitter

    International Nuclear Information System (INIS)

    Wang, C.L.; Davis, B.A.; Davies, T.J.; Nelson, M.A.; Thomas, M.C.; Zagarino, P.A.

    1987-01-01

    We report the results of an experiment in which we used an ultrafast, photoconductive, radiation detector to drive a fast laser-diode transmitter. When we irradiated the neutron-damaged Cr-doped GaAs detector with 17-MeV electron beams, the temporal response was measured to be less than 30 ps. The pulses from this detector modulated a fast GaAlAs laser diode to transmit the laser output through 30- and 1100-m optical fibers. Preliminary results indicate that 50- and 80-ps time resolutions, respectively, are obtainable with these fibers. We are now working to integrate the photoconductive detector and the laser diode transmitter into a single chip

  7. Ultrafast photoconductive detector-laser-diode transmitter

    International Nuclear Information System (INIS)

    Wang, C.L.; Davies, T.J.; Nelson, M.A.; Thomas, M.C.; Zagarino, P.A.; Davis, B.A.

    1987-01-01

    The authors report the results of an experiment in which they used an ultrafast, photoconductive, radiation detector to drive a fast laser-diode transmitter. When they irradiated the neutron-damaged Cr-doped Ga/As detector with 17-MeV electron beams, the temporal response of was measured to be less than 30 ps. The pulses from this detector modulated a fast GaAlAs laser diode to transmit the laser output through 30- and 1100-m optical fibers. Preliminary results indicate that 50- and 80-ps time resolutions, respectively, are obtainable with these fibers. They are now working to integrate the photoconductive detector and the laser diode transmitter into a single chip

  8. Thermal diode made by nematic liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Djair, E-mail: djfmelo@gmail.com [Instituto de Física, Universidade Federal de Alagoas, Av. Lourival Melo Mota, s/n, 57072-900 Maceió, AL (Brazil); Fernandes, Ivna [Instituto de Física, Universidade Federal de Alagoas, Av. Lourival Melo Mota, s/n, 57072-900 Maceió, AL (Brazil); Moraes, Fernando [Departamento de Física, CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900, João Pessoa, PB (Brazil); Departamento de Física, Universidade Federal Rural de Pernambuco, 52171-900 Recife, PE (Brazil); Fumeron, Sébastien [Institut Jean Lamour, Université de Lorraine, BP 239, Boulevard des Aiguillettes, 54506 Vandoeuvre les Nancy (France); Pereira, Erms [Escola Politécnica de Pernambuco, Universidade de Pernambuco, Rua Benfíca, 455, Madalena, 50720-001 Recife, PE (Brazil)

    2016-09-07

    This work investigates how a thermal diode can be designed from a nematic liquid crystal confined inside a cylindrical capillary. In the case of homeotropic anchoring, a defect structure called escaped radial disclination arises. The asymmetry of such structure causes thermal rectification rates up to 3.5% at room temperature, comparable to thermal diodes made from carbon nanotubes. Sensitivity of the system with respect to the heat power supply, the geometry of the capillary tube and the molecular anchoring angle is also discussed. - Highlights: • An escaped radial disclination as a thermal diode made by a nematic liquid crystal. • Rectifying effects comparable to those caused by carbon and boron nitride nanotubes. • Thermal rectification increasing with radius and decreasing with height of the tube. • Asymmetric BCs cause rectification from the spatial asymmetry produced by the escape. • Symmetric BCs provide rectifications smaller than those yields by asymmetric BCs.

  9. Diode array pumped, non-linear mirror Q-switched and mode-locked ...

    Indian Academy of Sciences (India)

    to control the air dispersion of the FW and SH beam by introducing proper phase shift between them and to achieve the maximum loss modulation. The laser output power at .... pulse train as a faithful replica of the fundamental train. But the correspondence between the central peak of the fundamental and that of the SH is ...

  10. Temperature persistent bistability and threshold switching in a single barrier heterostructure hot-electron diode

    DEFF Research Database (Denmark)

    Stasch, R.; Hey, R.; Asche, M.

    1996-01-01

    Bistable current–voltage characteristics caused by competition of tunneling through and field-enhanced thermionic emission across a single barrier are investigated in an n–-GaAs/Al0.34Ga0.66As/n+-GaAs structure. The S-shaped part of the characteristic persists in the whole temperature regime...

  11. All-Graphene Planar Self-Switching MISFEDs, Metal-Insulator-Semiconductor Field-Effect Diodes

    OpenAIRE

    Al-Dirini, Feras; Hossain, Faruque M.; Nirmalathas, Ampalavanapillai; Skafidas, Efstratios

    2014-01-01

    Graphene normally behaves as a semimetal because it lacks a bandgap, but when it is patterned into nanoribbons a bandgap can be introduced. By varying the width of these nanoribbons this band gap can be tuned from semiconducting to metallic. This property allows metallic and semiconducting regions within a single Graphene monolayer, which can be used in realising two-dimensional (2D) planar Metal-Insulator-Semiconductor field effect devices. Based on this concept, we present a new class of na...

  12. A Switch Is Not a Switch: Syntactically-Driven Bilingual Language Control

    Science.gov (United States)

    Gollan, Tamar H.; Goldrick, Matthew

    2018-01-01

    The current study investigated the possibility that language switches could be relatively automatically triggered by context. "Single-word switches," in which bilinguals switched languages on a single word in midsentence and then immediately switched back, were contrasted with more complete "whole-language switches," in which…

  13. Switching Activity Estimation of CIC Filter Integrators

    OpenAIRE

    Abbas, Muhammad; Gustafsson, Oscar

    2010-01-01

    In this work, a method for estimation of the switching activity in integrators is presented. To achieve low power, it is always necessary to develop accurate and efficient methods to estimate the switching activity. The switching activities are then used to estimate the power consumption. In our work, the switching activity is first estimated for the general purpose integrators and then it is extended for the estimation of switching activity in cascaded integrators in CIC filters. ©2010 I...

  14. Principles of broadband switching and networking

    CERN Document Server

    Liew, Soung C

    2010-01-01

    An authoritative introduction to the roles of switching and transmission in broadband integrated services networks Principles of Broadband Switching and Networking explains the design and analysis of switch architectures suitable for broadband integrated services networks, emphasizing packet-switched interconnection networks with distributed routing algorithms. The text examines the mathematical properties of these networks, rather than specific implementation technologies. Although the pedagogical explanations in this book are in the context of switches, many of the fundamenta

  15. 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....

  16. Laser-diode pumped Nd:YAG lasers; Laser diode reiki Nd:YAG lasear

    Energy Technology Data Exchange (ETDEWEB)

    Yuasa, H.; Akiyama, Y.; Nakayama, M. [Toshiba Corp., Tokyo (Japan)

    2000-04-01

    Laser-diode pumped Nd:YAG lasers are expected to be applied to laser processing fields such as welding, cutting, drilling, and marking due to their potential for high efficiency and compactness. We are designing and developing laser-diode pumped Nd:YAG lasers using numerical analysis simulation techniques such as ray tracing and thermal analysis. We have succeeded in achieving a laser power of more than 3 kW with 20% efficiency, which is the best ever obtained. In addition, we have developed a laser-diode pumped green laser by second harmonic generation, for precision machining on silicon wafers. (author)

  17. On-Demand Final State Control of a Surface-Bound Bistable Single Molecule Switch.

    Science.gov (United States)

    Garrido Torres, José A; Simpson, Grant J; Adams, Christopher J; Früchtl, Herbert A; Schaub, Renald

    2018-04-12

    Modern electronic devices perform their defined action because of the complete reliability of their individual active components (transistors, switches, diodes, and so forth). For instance, to encode basic computer units (bits) an electrical switch can be used. The reliability of the switch ensures that the desired outcome (the component's final state, 0 or 1) can be selected with certainty. No practical data storage device would otherwise exist. This reliability criterion will necessarily need to hold true for future molecular electronics to have the opportunity to emerge as a viable miniaturization alternative to our current silicon-based technology. Molecular electronics target the use of single-molecules to perform the actions of individual electronic components. On-demand final state control over a bistable unimolecular component has therefore been one of the main challenges in the past decade (1-5) but has yet to be achieved. In this Letter, we demonstrate how control of the final state of a surface-supported bistable single molecule switch can be realized. On the basis of the observations and deductions presented here, we further suggest an alternative strategy to achieve final state control in unimolecular bistable switches.

  18. Equilibrium double layers in extended Pierce diodes

    International Nuclear Information System (INIS)

    Ciubotariu-Jassy, C.I.

    1992-01-01

    The extended Pierce diode is similar to the standard (or classical) Pierce diode, but has passive circuit elements in place of the short circuit between the electrodes. This device is important as an approximation to real bounded plasma systems. It consists of two parallel plane electrodes (an emitter located at x=0 and a collector located at x=l) and a collisionless cold electron beam travelling between them. The electrons are neutralized by a background of comoving massive ions. This situation is analysed in this paper and new equilibrium double layer (DL) plasma structures are obtained. (author) 6 refs., 3 figs

  19. An all-silicon passive optical diode.

    Science.gov (United States)

    Fan, Li; Wang, Jian; Varghese, Leo T; Shen, Hao; Niu, Ben; Xuan, Yi; Weiner, Andrew M; Qi, Minghao

    2012-01-27

    A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input power is higher than the forward input. The silicon optical diode is ultracompact and is compatible with current complementary metal-oxide semiconductor processing.

  20. Diode and method of making the same

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, Jeramy Ray; Wierer, Jr., Jonathan; Kaplar, Robert; Allerman, Andrew A.

    2018-03-13

    A diode includes a second semiconductor layer over a first semiconductor layer. The diode further includes a third semiconductor layer over the second semiconductor layer, where the third semiconductor layer includes a first semiconductor element over the second semiconductor layer. The third semiconductor layer additionally includes a second semiconductor element over the second semiconductor layer, wherein the second semiconductor element surrounds the first semiconductor element. Further, the third semiconductor layer includes a third semiconductor element over the second semiconductor element. Furthermore, a hole concentration of the second semiconductor element is less than a hole concentration of the first semiconductor element.

  1. 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

  2. Flexible and twistable non-volatile memory cell array with all-organic one diode-one resistor architecture.

    Science.gov (United States)

    Ji, Yongsung; Zeigler, David F; Lee, Dong Su; Choi, Hyejung; Jen, Alex K-Y; Ko, Heung Cho; Kim, Tae-Wook

    2013-01-01

    Flexible organic memory devices are one of the integral components for future flexible organic electronics. However, high-density all-organic memory cell arrays on malleable substrates without cross-talk have not been demonstrated because of difficulties in their fabrication and relatively poor performances to date. Here we demonstrate the first flexible all-organic 64-bit memory cell array possessing one diode-one resistor architectures. Our all-organic one diode-one resistor cell exhibits excellent rewritable switching characteristics, even during and after harsh physical stresses. The write-read-erase-read output sequence of the cells perfectly correspond to the external pulse signal regardless of substrate deformation. The one diode-one resistor cell array is clearly addressed at the specified cells and encoded letters based on the standard ASCII character code. Our study on integrated organic memory cell arrays suggests that the all-organic one diode-one resistor cell architecture is suitable for high-density flexible organic memory applications in the future.

  3. Switching dynamics of TaOx-based threshold switching devices

    Science.gov (United States)

    Goodwill, Jonathan M.; Gala, Darshil K.; Bain, James A.; Skowronski, Marek

    2018-03-01

    Bi-stable volatile switching devices are being used as access devices in solid-state memory arrays and as the active part of compact oscillators. Such structures exhibit two stable states of resistance and switch between them at a critical value of voltage or current. A typical resistance transient under a constant amplitude voltage pulse starts with a slow decrease followed by a rapid drop and leveling off at a low steady state value. This behavior prompted the interpretation of initial delay and fast transition as due to two different processes. Here, we show that the entire transient including incubation time, transition time, and the final resistance values in TaOx-based switching can be explained by one process, namely, Joule heating with the rapid transition due to the thermal runaway. The time, which is required for the device in the conducting state to relax back to the stable high resistance one, is also consistent with the proposed mechanism.

  4. Linear variable voltage diode capacitor and adaptive matching networks

    NARCIS (Netherlands)

    Larson, L.E.; De Vreede, L.C.N.

    2006-01-01

    An integrated variable voltage diode capacitor topology applied to a circuit providing a variable voltage load for controlling variable capacitance. The topology includes a first pair of anti-series varactor diodes, wherein the diode power-law exponent n for the first pair of anti-series varactor

  5. Cryogenic thermometry with a common diode: type BAS16

    NARCIS (Netherlands)

    Rijpma, A.P.; ter Brake, Hermanus J.M.

    2006-01-01

    Cryogenic test experiments often require a large number of temperatures to be monitored. In order to reduce cost, we investigated the feasibility of low-cost common diodes. We chose the Philips BAS16 diode in a type SOT23 package. By means of Stycast 2850FT, these diodes were glued into alumina

  6. High power diode lasers converted to the visible

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Hansen, Anders Kragh; Andersen, Peter E.

    2017-01-01

    High power diode lasers have in recent years become available in many wavelength regions. However, some spectral regions are not well covered. In particular, the visible spectral range is lacking high power diode lasers with good spatial quality. In this paper, we highlight some of our recent...... results in nonlinear frequency conversion of high power near infrared diode lasers to the visible spectral region....

  7. High brightness direct diode laser with kW output power

    Science.gov (United States)

    Fritsche, Haro; Kruschke, Bastian; Koch, Ralf; Ferrario, Fabio; Kern, Holger; Pahl, Ulrich; Pflueger, Silke; Gries, Wolfgang

    2014-03-01

    High power, high brightness diode lasers are beginning to challenge solid state lasers, i.e. disk and fiber lasers. The core technologies for brightness scaling of diode lasers are optical stacking and dense spectral combining (DSC), as well as improvements of the diode material. Diode lasers will have the lowest cost of ownership, highest efficiency and most compact design among all lasers. In our modular product design tens of single emitters are combined in a compact package and launched into a 200 μm fiber with 0.08 NA. Dense spectral combining enables power scaling from 80 W to kilowatts. Volume Bragg Gratings and dichroic filters yield high optical efficiencies of more than 80% at low cost. Each module emits up to 500 W with a beam quality of 5.5 mm*mrad and less than 20 nm linewidth. High speed switching power supplies are integrated into the module and rise times as short as 6 μs have been demonstrated. Fast control algorithms based on FPGA and embedded microcontroller ensure high wall plug efficiency with a unique control loop time of only 30 μs. Individual modules are spectrally combined to result in direct diode laser systems with kilowatts of output power at identical beam quality. For low loss fiber coupling a 200 μm fiber is used and the NA is limited to 0.08 corresponding to a beam quality of 7.5 mm*mrad. The controller architecture is fully scalable without sacrificing loop time. We leverage automated manufacturing for cost effective, high yield production. A precision robotic system handles and aligns the individual fast axis lenses and tracks all quality relevant data. Similar technologies are also deployed for dense spectral combining aligning the VBG and dichroic filters. Operating at wavelengths between 900 nm and 1100 nm, these systems are mainly used in cutting and welding, but the technology can also be adapted to other wavelength ranges, such as 793 nm and 1530 nm. Around 1.5 μm the diodes are already successfully used for resonant

  8. IGBT: a solid state switch

    International Nuclear Information System (INIS)

    Chatroux, D.; Maury, J.; Hennevin, B.

    1993-01-01

    A Copper Vapour Laser Power Supply has been designed using a solid state switch consisting in eighteen Isolated Gate Bipolar Transistors (IGBT), -1200 volts, 400 Amps, each-in parallel. This paper presents the Isolated Gate Bipolar Transistor (IGBTs) replaced in the Power Electronic components evolution, and describes the IGBT conduction mechanism, presents the parallel association of IGBTs, and studies the application of these components to a Copper Vapour Laser Power Supply. The storage capacitor voltage is 820 volts, the peak current of the solid state switch is 17.000 Amps. The switch is connected on the primary of a step-up transformer, followed by a magnetic modulator. The reset of the magnetic modulator is provided by part of the laser reflected energy with a patented circuit. The charging circuit is a resonant circuit with a charge controlled by an IGBT switch. When the switch is open, the inductance energy is free-wheeled by an additional winding and does not extend the charging phase of the storage capacitor. The design allows the storage capacitor voltage to be very well regulated. This circuit is also patented. The electric pulse in the laser has 30.000 Volt peak voltage, 2000 Amp peak current, and is 200 nanoseconds long, for a 200 Watt optical power Copper Vapour Laser

  9. Photoresistance switching of plasmonic nanopores.

    Science.gov (United States)

    Li, Yi; Nicoli, Francesca; Chen, Chang; Lagae, Liesbet; Groeseneken, Guido; Stakenborg, Tim; Zandbergen, Henny W; Dekker, Cees; Van Dorpe, Pol; Jonsson, Magnus P

    2015-01-14

    Fast and reversible modulation of ion flow through nanosized apertures is important for many nanofluidic applications, including sensing and separation systems. Here, we present the first demonstration of a reversible plasmon-controlled nanofluidic valve. We show that plasmonic nanopores (solid-state nanopores integrated with metal nanocavities) can be used as a fluidic switch upon optical excitation. We systematically investigate the effects of laser illumination of single plasmonic nanopores and experimentally demonstrate photoresistance switching where fluidic transport and ion flow are switched on or off. This is manifested as a large (∼ 1-2 orders of magnitude) increase in the ionic nanopore resistance and an accompanying current rectification upon illumination at high laser powers (tens of milliwatts). At lower laser powers, the resistance decreases monotonically with increasing power, followed by an abrupt transition to high resistances at a certain threshold power. A similar rapid transition, although at a lower threshold power, is observed when the power is instead swept from high to low power. This hysteretic behavior is found to be dependent on the rate of the power sweep. The photoresistance switching effect is attributed to plasmon-induced formation and growth of nanobubbles that reversibly block the ionic current through the nanopore from one side of the membrane. This explanation is corroborated by finite-element simulations of a nanobubble in the nanopore that show the switching and the rectification.

  10. Tradeoff between laser diodes and light-emitting diodes (LEDs) for the common weapon control system

    Science.gov (United States)

    Greenwell, R. A.

    1982-07-01

    The use of laser diodes or light emitting diodes (LEDs) for the ground-launched cruise missile (GLCM) is comparatively evaluated. Source characteristics of interest, including radiated power output, spectral width and peak emission, modulation bandwidth, size coupling efficiency, lifetime, rise time, and price, are presented for noncoherent LED and the coherent laser diode. The advantages and disadvantages of laser diodes and LEDs are briefly discussed, and nuclear explosion effects on these instruments, including catastrophic damage, transient ionization effects, and permanent degradation, are summarized. A link analysis of the cable parameters required for the GLCM fiber optic data link is given, arriving at power levels consistent with a LED-PIN link. Two LEDs which meet these requirements are briefly discussed.

  11. Portable Userspace Virtual Filesystem Switch

    Directory of Open Access Journals (Sweden)

    Łukasz Faber

    2013-01-01

    Full Text Available Multiple different filesystems — including disk-based, network, distributed, abstract — arean integral part of every operating system. They are usually written as kernel modules and abstracted to the user via a virtual filesystem switch. In this paper we analyse the feasibility of reimplementing the virtual filesystem switch as a userspace daemon and applicability of this approach in real-life usage. Such reimplementation will require a way to virtualise processes behaviour related to filesystem operations. The problem is non-trivial, as we assume limited capabilities of the VFS switch implemented in userspace. We present a layered architecture comprising of a monitoring process, the VFS abstraction and real filesystem implementations. All working in userspace. Then, we evaluate this solution in four areas: portability, feasibility, usability and performance. Our results demonstrate possible gains in using the userspace-based approach with monolithic kernels, but also underline problems that are encountered in this approach.

  12. Tunnel Diode Discriminator with Fixed Dead Time

    DEFF Research Database (Denmark)

    Diamond, J. M.

    1965-01-01

    A solid state discriminator for the range 0.4 to 10 V is described. Tunnel diodes are used for the discriminator element and in a special fixed dead time circuit. An analysis of temperature stability is presented. The regulated power supplies are described, including a special negative resistance...

  13. Light-Emitting Diodes: A Hidden Treasure

    Science.gov (United States)

    Planinšic, Gorazd; Etkina, Eugenia

    2014-01-01

    LEDs, or light-emitting diodes, are cheap, easy to purchase, and thus commonly used in physics instruction as indicators of electric current or as sources of light (Fig. 1). In our opinion LEDs represent a unique piece of equipment that can be used to collect experimental evidence, and construct and test new ideas in almost every unit of a general…

  14. Light-Emitting Diodes: Learning New Physics

    Science.gov (United States)

    Planinšic, Gorazd; Etkina, Eugenia

    2015-01-01

    This is the third paper in our Light-Emitting Diodes series. The series aims to create a systematic library of LED-based materials and to provide the readers with the description of experiments and pedagogical treatment that would help their students construct, test, and apply physics concepts and mathematical relations. The first paper, published…

  15. Fluorescence lifetime imaging using light emitting diodes

    International Nuclear Information System (INIS)

    Kennedy, Gordon T; Munro, Ian; Poher, Vincent; French, Paul M W; Neil, Mark A A; Elson, Daniel S; Hares, Jonathan D

    2008-01-01

    We demonstrate flexible use of low cost, high-power light emitting diodes as illumination sources for fluorescence lifetime imaging (FLIM). Both time-domain and frequency-domain techniques have been implemented at wavelengths spanning the range 450-640 nm. Additionally, we demonstrate optically sectioned fluorescence lifetime imaging by combining structured illumination with frequency-domain FLIM

  16. High-Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal

    2010-01-01

    We demonstrate single nanowire tunnel diodes with room temperature peak current densities of up to 329 A/cm(2). Despite the large surface to volume ratio of the type-II InP-GaAs axial heterostructure nanowires, we measure peak to valley current ratios (PVCR) of up to 8.2 at room temperature and 27...

  17. All epitaxial silicon diode heavy ion detector

    International Nuclear Information System (INIS)

    Gruhn, C.R.; Goldstone, P.D.; Jarmie, N.

    1976-01-01

    An all epitaxial silicon diode (ESD) heavy ion detector has been designed, fabricated, and tested. The active area of the detector is 5 cm 2 and has a total thickness of 50 μ. The response of the detector has been studied with fission fragments, alpha particles, oxygen ions, and sulfur ions. A number of advantages in terms of both fabrication and performance are discussed

  18. Entangled Light Emission From a Diode

    International Nuclear Information System (INIS)

    Stevenson, R. M.; Shields, A. J.; Salter, C. L.; Farrer, I.; Nicoll, C. A.; Ritchie, D. A.

    2011-01-01

    Electrically-driven entangled photon generation is demonstrated for the first time using a single semiconductor quantum dot embedded in a light emitting diode structure. The entanglement fidelity is shown to be of sufficient quality for applications such as quantum key distribution.

  19. The Fuge Tube Diode Array Spectrophotometer

    Science.gov (United States)

    Arneson, B. T.; Long, S. R.; Stewart, K. K.; Lagowski, J. J.

    2008-01-01

    We present the details for adapting a diode array UV-vis spectrophotometer to incorporate the use of polypropylene microcentrifuge tubes--fuge tubes--as cuvettes. Optical data are presented validating that the polyethylene fuge tubes are equivalent to the standard square cross section polystyrene or glass cuvettes generally used in…

  20. Microring Diode Laser for THz Generation

    DEFF Research Database (Denmark)

    Mariani, S.; Andronico, A.; Favero, I.

    2013-01-01

    We report on the modeling and optical characterization of AlGaAs/InAs quantum-dot microring diode lasers designed for terahertz (THz) difference frequency generation (DFG) between two whispering gallery modes (WGMs) around 1.3 $\\mu$m. In order to investigate the spectral features of this active...

  1. Outcome of Diode Laser Cyclophotocoagulation in Neovascular ...

    African Journals Online (AJOL)

    Aim: To find out the short-term outcome of ciliary ablation with diode laser contact cyclophotocoagulation in Nigerians with neovascular glaucoma. Methods: The study is a retrospective, non-comparative, interventional case series. Demographic data, ocular and systemic history were obtained. Clinical examination included ...

  2. Effects Of Environmental And Operational Stresses On RF MEMS Switch Technologies For Space Applications

    Science.gov (United States)

    Jah, Muzar; Simon, Eric; Sharma, Ashok

    2003-01-01

    Micro Electro Mechanical Systems (MEMS) have been heralded for their ability to provide tremendous advantages in electronic systems through increased electrical performance, reduced power consumption, and higher levels of device integration with a reduction of board real estate. RF MEMS switch technology offers advantages such as low insertion loss (0.1- 0.5 dB), wide bandwidth (1 GHz-100 GHz), and compatibility with many different process technologies (quartz, high resistivity Si, GaAs) which can replace the use of traditional electronic switches, such as GaAs FETS and PIN Diodes, in microwave systems for low signal power (x technologies, the unknown reliability, due to the lack of information concerning failure modes and mechanisms inherent to MEMS devices, create an obstacle to insertion of MEMS technology into high reliability applications. All MEMS devices are sensitive to moisture and contaminants, issues easily resolved by hermetic or near-hermetic packaging. Two well-known failure modes of RF MEMS switches are charging in the dielectric layer of capacitive membrane switches and contact interface stiction of metal-metal switches. Determining the integrity of MEMS devices when subjected to the shock, vibration, temperature extremes, and radiation of the space environment is necessary to facilitate integration into space systems. This paper will explore the effects of different environmental stresses, operational life cycling, temperature, mechanical shock, and vibration on the first commercially available RF MEMS switches to identify relevant failure modes and mechanisms inherent to these device and packaging schemes for space applications. This paper will also describe RF MEMS Switch technology under development at NASA GSFC.

  3. Manufacture of axially insulated large-area diodes

    International Nuclear Information System (INIS)

    Ma Weiyi; Zhou Kungang; Wang Youtian; Zhang Dong; Shan Yusheng; Wang Naiyan

    1999-01-01

    The author describes the design and construction of the axially insulated large-area diodes used in the 'Heaven-1'. The four axially insulated large-area diodes are connected to the 10 ohm pulse transmission lines via the vacuum feed through tubes. The experimental results with the diodes are given. The diodes can steadily work at the voltage of 650 kV, and the diode current density is about 80 A per cm 2 with a pulse width of 220 ns. The electron beams with a total energy of 25 kJ are obtained

  4. All-fiber polarization switch

    Science.gov (United States)

    Knape, Harald; Margulis, Walter

    2007-03-01

    We report an all-fiber polarization switch made out of silica-based microstructured fiber suitable for Q-switching all-fiber lasers. Nanosecond high-voltage pulses are used to heat and expand an internal electrode to cause λ/2-polarization rotation in less than 10 ns for 1.5 μm light. The 10 cm long component has an experimentally measured optical insertion loss of 0.2 dB and a 0-10 kHz repetition frequency capacity and has been durability tested for more than 109 pulses.

  5. Industry switching in developing countries

    DEFF Research Database (Denmark)

    Newman, Carol; Rand, John; Tarp, Finn

    2013-01-01

    Firm turnover (i.e., firm entry and exit) is a well-recognized source of sector-level productivity growth. In contrast, the role and importance of firms that switch activities from one sector to another is not well understood. Firm switchers are likely to be unique, differing from both newly...... and behavior than do entry and exit firms. Switchers tend to be labor intensive and to seek competitive opportunities in labor-intensive sectors in response to changes in market environments. Moreover, resource reallocation resulting from switching forms an important component of productivity growth. The topic...

  6. CMOS integrated switching power converters

    CERN Document Server

    Villar-Pique, Gerard

    2011-01-01

    This book describes the structured design and optimization of efficient, energy processing integrated circuits. The approach is multidisciplinary, covering the monolithic integration of IC design techniques, power electronics and control theory. In particular, this book enables readers to conceive, synthesize, design and implement integrated circuits with high-density high-efficiency on-chip switching power regulators. Topics covered encompass the structured design of the on-chip power supply, efficiency optimization, IC-compatible power inductors and capacitors, power MOSFET switches and effi

  7. The Pierce-diode approximation to the single-emitter plasma diode

    International Nuclear Information System (INIS)

    Ender, A. Ya.; Kuhn, S.; Kuznetsov, V. I.

    2006-01-01

    The possibility of modeling fast processes in the collisionless single-emitter plasma diode (Knudsen diode with surface ionization, KDSI) by means of the Pierce-diode is studied. The KDSI is of practical importance in that it is an almost exact model of thermionic energy converters (TICs) in the collisionless regime and can also be used to model low-density Q-machines. At high temperatures, the Knudsen TIC comes close to the efficiency of the Carnot cycle and hence is the most promising converter of thermal to electric energy. TICs can be applied as component parts in high-temperature electronics. It is shown that normalizations must be chosen appropriately in order to compare the plasma characteristics of the two models: the KDSI and the Pierce-diode. A linear eigenmode theory of the KDSI is developed. For both nonlinear time-independent states and linear eigenmodes without electron reflection, excellent agreement is found between the analytical potential distributions for the Pierce-diode and the corresponding numerical ones for the KDSI. For the states with electron reflection, the agreement is satisfactory in a qualitative sense. A full classification of states of both diodes for the regimes with and without electron reflection is presented. The effect of the thermal spread in electron velocities on the potential distributions and the (ε,η) diagrams is analyzed. Generally speaking, the methodology developed is usefully applicable to a variety of systems in which the electrons have beam-like distributions

  8. 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.

  9. Photon response of silicon diode neutron detectors

    International Nuclear Information System (INIS)

    McCall, R.C.; Jenkins, T.M.; Oliver, G.D. Jr.

    1976-07-01

    The photon response of silicon diode neutron detectors was studied to solve the problem on detecting neutrons in the presence of high energy photons at accelerator neutron sources. For the experiment Si diodes, Si discs, and moderated activation foil detectors were used. The moderated activation foil detector consisted of a commercial moderator and indium foils 2'' in diameter and approximately 2.7 grams each. The moderator is a cylinder of low-density polyethylene 6 1 / 4 '' in diameter by 6 1 / 16 '' long covered with 0.020'' of cadmium. Neutrons are detected by the reaction 115 In (n,γ) 116 In(T/sub 1 / 2 / = 54 min). Photons cannot be detected directly but photoneutrons produced in the moderator assembly can cause a photon response. The Si discs were thin slices of single-crystal Si about 1.4 mils thick and 1'' in diameter which were used as activation detectors, subsequently being counted on a thin-window pancake G.M. counter. The Si diode fast neutron dosimeter 5422, manufactured by AB Atomenergi in Studsvik, Sweden, consists of a superdoped silicon wafer with a base width of 0.050 inches between two silver contacts coated with 2 mm of epoxy. For this experiment, the technique of measuring the percent change of voltage versus dose was used. Good precision was obtained using both unirradiated and preirradiated diodes. All diodes, calibrated against 252 CF in air,were read out 48 hours after irradiation to account for any room temperature annealing. Results are presented and discussed

  10. Wavelength conversion in optical packet switching

    DEFF Research Database (Denmark)

    Danielsen, Søren Lykke; Hansen, Peter Bukhave; Stubkjær, Kristian

    1998-01-01

    A detailed traffic analysis of optical packet switch design is performed. Special consideration is given to the complexity of the optical buffering and the overall switch block structure is considered in general. Wavelength converters are shown to improve the traffic performance of the switch...... blocks for both random and bursty traffic. Furthermore, the traffic performance of switch blocks with add-drop switches has been assessed in a Shufflenetwork showing the advantage of having converters at the inlets. Finally, the aspect of synchronization is discussed through a proposal to operate...... the packet switch block asynchronously, i.e. without packet alignment at the input...

  11. Switching in electrical transmission and distribution systems

    CERN Document Server

    Smeets, René; Kapetanovic, Mirsad; Peelo, David F; Janssen, Anton

    2014-01-01

    Switching in Electrical Transmission and Distribution Systems presents the issues and technological solutions associated with switching in power systems, from medium to ultra-high voltage. The book systematically discusses the electrical aspects of switching, details the way load and fault currents are interrupted, the impact of fault currents, and compares switching equipment in particular circuit-breakers. The authors also explain all examples of practical switching phenomena by examining real measurements from switching tests. Other highlights include: up to date commentary on new develo

  12. The Beam Characteristics of High Power Diode Laser Stack

    Science.gov (United States)

    Gu, Yuanyuan; Fu, Yueming; Lu, Hui; Cui, Yan

    2018-03-01

    Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. However, the poor quality of diode laser beam itself, directly affect its application ranges, in order to better use of diode laser stack, need a proper correction of optical system, which requires accurate understanding of the diode laser beam characteristics. Diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. Therefore diode laser cladding will open a new field of repairing for the damaged machinery parts which must contribute to recycling of the used machines and saving of cost.

  13. Multiuser switched diversity scheduling schemes

    KAUST Repository

    Shaqfeh, Mohammad

    2012-09-01

    Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.

  14. Soliton switching in directional couplers

    NARCIS (Netherlands)

    Valkering, T.P.; Hoekstra, Hugo; de Boer, Pieter-Tjerk

    1999-01-01

    The mechanism of pulse switching is investigated analytically and numerically for a family of initial conditions with a solitonlike pulse in one channel and no signal on the other channel of the coupler. This investigation is performed directly in the coupled nonlinear Schroedinger equations that

  15. Intrinsic nanofilamentation in resistive switching

    KAUST Repository

    Wu, Xing

    2013-03-15

    Resistive switching materials are promising candidates for nonvolatile data storage and reconfiguration of electronic applications. Intensive studies have been carried out on sandwiched metal-insulator-metal structures to achieve high density on-chip circuitry and non-volatile memory storage. Here, we provide insight into the mechanisms that govern highly reproducible controlled resistive switching via a nanofilament by using an asymmetric metal-insulator-semiconductor structure. In-situ transmission electron microscopy is used to study in real-time the physical structure and analyze the chemical composition of the nanofilament dynamically during resistive switching. Electrical stressing using an external voltage was applied by a tungsten tip to the nanosized devices having hafnium oxide (HfO2) as the insulator layer. The formation and rupture of the nanofilaments result in up to three orders of magnitude change in the current flowing through the dielectric during the switching event. Oxygen vacancies and metal atoms from the anode constitute the chemistry of the nanofilament.

  16. Switching Costs in Accounting Services

    Directory of Open Access Journals (Sweden)

    Fatih Koç

    2015-06-01

    Full Text Available Switching cost is defined as possible costs that customers may encounter when they want to change the firm they buy service, and an important subject in terms of accounting services. Particularly, small business entrepreneurs’ not having knowledge about accounting procedures, and sharing private information with accounting firms make switching costs more important for accounting services. Thus, the aim of this study is to investigate the concept of switching costs (relational cost, procedural cost and financial cost, its determinants (perceived service quality, service importance, and service failures, and consequences (re-purchasing, and recommen ding to others. Theresearch was conducted on small business entrepreneurs in down-town of Balıkesir in Turkey. Total 405 small business entrepreneur owners were interviewed. According to results of the study, perceived service quality positively affects all dimensions of switching costs, significance of service positively affects procedural and relational costs, and service failures negatively affect procedural and relational costs. The results showed that while procedural and relational costs positively affect re-purchasing and recommending to others variables, financial cost did not have any effect on these variables.

  17. Nanoscale organic ferroelectric resistive switches

    NARCIS (Netherlands)

    Khikhlovskyi, V.; Wang, R.; Breemen, A.J.J.M. van; Gelinck, G.H.; Janssen, R.A.J.; Kemerink, M.

    2014-01-01

    Organic ferroelectric resistive switches function by grace of nanoscale phase separation in a blend of a semiconducting and a ferroelectric polymer that is sandwiched between metallic electrodes. In this work, various scanning probe techniques are combined with numerical modeling to unravel their

  18. Switching processes in financial markets.

    Science.gov (United States)

    Preis, Tobias; Schneider, Johannes J; Stanley, H Eugene

    2011-05-10

    For an intriguing variety of switching processes in nature, the underlying complex system abruptly changes from one state to another in a highly discontinuous fashion. Financial market fluctuations are characterized by many abrupt switchings creating upward trends and downward trends, on time scales ranging from macroscopic trends persisting for hundreds of days to microscopic trends persisting for a few minutes. The question arises whether these ubiquitous switching processes have quantifiable features independent of the time horizon studied. We find striking scale-free behavior of the transaction volume after each switching. Our findings can be interpreted as being consistent with time-dependent collective behavior of financial market participants. We test the possible universality of our result by performing a parallel analysis of fluctuations in time intervals between transactions. We suggest that the well known catastrophic bubbles that occur on large time scales--such as the most recent financial crisis--may not be outliers but single dramatic representatives caused by the formation of increasing and decreasing trends on time scales varying over nine orders of magnitude from very large down to very small.

  19. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-07-03

    Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6HSiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators.

  20. Androgenic switch in barley microspores

    NARCIS (Netherlands)

    de Faria Maraschin, Simone

    2005-01-01

    Barley androgenesis represents an attractive system to study stress-induced cell differentiation and is a valuable tool for efficient plant breeding. The switch from the pollen developmental pathway towards an androgenic route involves several well-described morphological changes. However, little is

  1. Incorrect predictions reduce switch costs.

    Science.gov (United States)

    Kleinsorge, Thomas; Scheil, Juliane

    2015-07-01

    In three experiments, we combined two sources of conflict within a modified task-switching procedure. The first source of conflict was the one inherent in any task switching situation, namely the conflict between a task set activated by the recent performance of another task and the task set needed to perform the actually relevant task. The second source of conflict was induced by requiring participants to guess aspects of the upcoming task (Exps. 1 & 2: task identity; Exp. 3: position of task precue). In case of an incorrect guess, a conflict accrues between the representation of the guessed task and the actually relevant task. In Experiments 1 and 2, incorrect guesses led to an overall increase of reaction times and error rates, but they reduced task switch costs compared to conditions in which participants predicted the correct task. In Experiment 3, incorrect guesses resulted in faster performance overall and to a selective decrease of reaction times in task switch trials when the cue-target interval was long. We interpret these findings in terms of an enhanced level of controlled processing induced by a combination of two sources of conflict converging upon the same target of cognitive control. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. The Atlas load protection switch

    CERN Document Server

    Davis, H A; Dorr, G; Martínez, M; Gribble, R F; Nielsen, K E; Pierce, D; Parsons, W M

    1999-01-01

    Atlas is a high-energy pulsed-power facility under development to study materials properties and hydrodynamics experiments under extreme conditions. Atlas will implode heavy liner loads (m~45 gm) with a peak current of 27-32 MA delivered in 4 mu s, and is energized by 96, 240 kV Marx generators storing a total of 23 MJ. A key design requirement for Atlas is obtaining useful data for 95601130f all loads installed on the machine. Materials response calculations show current from a prefire can damage the load requiring expensive and time consuming replacement. Therefore, we have incorporated a set of fast-acting mechanical switches in the Atlas design to reduce the probability of a prefire damaging the load. These switches, referred to as the load protection switches, short the load through a very low inductance path during system charge. Once the capacitors have reached full charge, the switches open on a time scale short compared to the bank charge time, allowing current to flow to the load when the trigger pu...

  3. Diode-pumped, single frequency Nd:YLF laser for 60-beam OMEGA laser pulse-shaping system

    International Nuclear Information System (INIS)

    Okishev, A.V.; Seka, W.

    1997-01-01

    The operational conditions of the OMEGA pulse-shaping system require an extremely reliable and low-maintenance master oscillator. The authors have developed a diode-pumped, single-frequency, pulsed Nd:YLF laser for this application. The laser generates Q-switched pulses of ∼160-ns duration and ∼10-microJ energy content at the 1,053-nm wavelength with low amplitude fluctuations (<0.6% rms) and low temporal jitter (<7 ns rms). Amplitude and frequency feedback stabilization systems have been used for high long-term amplitude and frequency stability

  4. Driving of a GaN enhancement mode HEMT transistor with zener diode protection for high efficiency and low EMI

    OpenAIRE

    Spro, Ole Christian; Basu, Supratim; Abuishmais, Ibrahim Abed; Midtgård, Ole-Morten; Undeland, Tore Marvin

    2017-01-01

    The ultra-low gate charge characteristics and low gate voltage limitation of a GaN enhancement mode HEMT in combination with stray circuit elements poses many challenges of driving them in power electronic applications. This paper investigates the effect of changing gate resistances and including a Zener diode for overvoltage protection in the gate circuit. The goal is to achieve low switching losses and low EMC signature. Due to the very low gate capacitance of the GaN HEMT compared to the j...

  5. Diode-Pumped Long-Pulse-Length Ho:Tm:YLiF4 Laser at 10 Hz

    Science.gov (United States)

    Jani, Mahendra G.; Naranjo, Felipe L.; Barnes, Norman P.; Murray, Keith E.; Lockard, George E.

    1995-01-01

    An optical efficiency of 0.052 under normal mode operation for diode-pumped Ho:Tm:YLiF4 at a pulse repetition frequency of 10 Hz has been achieved. Laser output energy of 30 mJ in single Q-switched pulses with 600-ns pulse length were obtained for an input energy of 3 J. A diffusion-bonded birefringent laser rod consisting of Ho:Tm-doped and undoped pieces of YLF was utilized for 10-Hz operation.

  6. A Novel Voltage Equalization Charger Using Capacitors, Diodes, and an AC Power Source for Energy Storage Cells

    Science.gov (United States)

    Uno, Masatoshi; Tanaka, Koji

    Conventional voltage equalizers or equalization chargers, which are used for series-connected energy storage cells to eliminate cell voltage imbalance, consisting of a number of switches or transformers tend to be complex with the number of series connection of the energy storage cells. A novel voltage equalization charger consisting only of capacitors, diodes, and an ac power source is proposed, and its dc equivalent circuit expressed by resistors and a dc power source is derived in this paper. Experimental charge tests demonstrated that series-connected EDLCs could be charged up to the uniform voltage by the proposed equalization charger.

  7. Switch-connected HyperX network

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dong; Heidelberger, Philip

    2018-02-13

    A network system includes a plurality of sub-network planes and global switches. The sub-network planes have a same network topology as each other. Each of the sub-network planes includes edge switches. Each of the edge switches has N ports. Each of the global switches is configured to connect a group of edge switches at a same location in the sub-network planes. In each of the sub-network planes, some of the N ports of each of the edge switches are connected to end nodes, and others of the N ports are connected to other edge switches in the same sub-network plane, other of the N ports are connected to at least one of the global switches.

  8. Wide Bandgap Extrinsic Photoconductive Switches

    Science.gov (United States)

    Sullivan, James Stephen

    Wide Bandgap Extrinsic Photoconductive Switches Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6H-SiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators. The successful development of a vanadium compensated, 6H-SiC extrinsic photoconductive switch for use as a closing switch for compact accelerator applications was realized by improvements made to the vanadium, nitrogen and boron impurity densities. The changes made to the impurity densities were based on the physical intuition outlined and simple rate equation models. The final 6H-SiC impurity 'recipe' calls for vanadium, nitrogen and boron densities of 2.5 e17 cm-3, 1.25e17 cm-3 and ≤ 1e16 cm-3, respectively. This recipe was originally developed to maximize the quantum efficiency of the vanadium compensated 6H-SiC, while maintaining a thermally stable semi-insulating material. The rate equation models indicate that, besides increasing the quantum efficiency, the impurity recipe should be expected to also increase the carrier recombination time. Three generations of 6H-SiC materials were tested. The

  9. Comparison of Small-Scale Actively and Passively Q-Switched Eye-Safe Intracavity Optical Parametric Oscillators at 1.57 μm

    International Nuclear Information System (INIS)

    Miao Jie-Guang; Pan Yu-Zhai; Qu Shi-Liang

    2012-01-01

    The first experimental comparison between the actively and passively Q-switched intracavity optical parametric oscillators (IOPOs) at 1.57 μm driven by a small-scale diode-pumped Nd:YVO 4 laser are thoroughly presented. It is found that the performances of the two types of IOPOs are complementary. The actively Q-switched IOPO features a shorter pulse duration, a higher peak power, and a superior power and pulse stability. However, in terms of compactness, operation threshold and conversion efficiency, passively Q-switched IOPOs are more attractive. It is further indicated that the passively Q-switched IOPO at 1.57μm is a promising and cost-effective eye-safe laser source, especially at the low and moderate output levels. In addition, instructional improvement measures for the two types of IOPOs are also summarized. (fundamental areas of phenomenology(including applications))

  10. Solution-Grown ZnO Films toward Transparent and Smart Dual-Color Light-Emitting Diode.

    Science.gov (United States)

    Huang, Xiaohu; Zhang, Li; Wang, Shijie; Chi, Dongzhi; Chua, Soo Jin

    2016-06-22

    An individual light-emitting diode (LED) capable of emitting different colors of light under different bias conditions not only allows for compact device integration but also extends the functionality of the LED beyond traditional illumination and display. Herein, we report a color-switchable LED based on solution-grown n-type ZnO on p-GaN/n-GaN heterojunction. The LED emits red light with a peak centered at ∼692 nm and a full width at half-maximum of ∼90 nm under forward bias, while it emits green light under reverse bias. These two lighting colors can be switched repeatedly by reversing the bias polarity. The bias-polarity-switched dual-color LED enables independent control over the lighting color and brightness of each emission with two-terminal operation. The results offer a promising strategy toward transparent, miniaturized, and smart LEDs, which hold great potential in optoelectronics and optical communication.

  11. Diode laser lidar wind velocity sensor using a liquid-crystal retarder for non-mechanical beam-steering

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Iversen, Theis Faber Quist; Hu, Qi

    2014-01-01

    the lidar probe beam in two different lines-of-sight (LOS) with a 60° angular separation. Dual-LOS beam-steering isimplemented optically with no moving parts by means of a controllableliquid-crystal retarder (LCR). The LCR switches the polarization betweentwo orthogonal linear states of the lidar beam so......We extend the functionality of a low-cost CW diode lasercoherent lidar from radial wind speed (scalar) sensing to wind velocity(vector) measurements. Both speed and horizontal direction of the wind at~80 m remote distance are derived from two successive radial speedestimates by alternately steering...... it either transmits throughor reflects off a polarization splitter. The room-temperature switching timebetween the two LOS is measured to be in the order of 100μs in one switchdirection but 16 ms in the opposite transition. Radial wind speedmeasurement (at 33 Hz rate) while the lidar beam is repeatedly...

  12. Can small field diode correction factors be applied universally?

    Science.gov (United States)

    Liu, Paul Z Y; Suchowerska, Natalka; McKenzie, David R

    2014-09-01

    Diode detectors are commonly used in dosimetry, but have been reported to over-respond in small fields. Diode correction factors have been reported in the literature. The purpose of this study is to determine whether correction factors for a given diode type can be universally applied over a range of irradiation conditions including beams of different qualities. A mathematical relation of diode over-response as a function of the field size was developed using previously published experimental data in which diodes were compared to an air core scintillation dosimeter. Correction factors calculated from the mathematical relation were then compared those available in the literature. The mathematical relation established between diode over-response and the field size was found to predict the measured diode correction factors for fields between 5 and 30 mm in width. The average deviation between measured and predicted over-response was 0.32% for IBA SFD and PTW Type E diodes. Diode over-response was found to be not strongly dependent on the type of linac, the method of collimation or the measurement depth. The mathematical relation was found to agree with published diode correction factors derived from Monte Carlo simulations and measurements, indicating that correction factors are robust in their transportability between different radiation beams. Copyright © 2014. Published by Elsevier Ireland Ltd.

  13. 49 CFR 236.822 - Switch, spring.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Switch, spring. 236.822 Section 236.822... Switch, spring. A switch equipped with a spring device which forces the points to their original position after being trailed through and holds them under spring compression. ...

  14. A gain-coefficient switched Alexandrite laser

    International Nuclear Information System (INIS)

    Lee, Chris J; Van der Slot, Peter J M; Boller, Klaus-J

    2013-01-01

    We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.

  15. Bootstrapped Low-Voltage Analog Switches

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1999-01-01

    Novel low-voltage constant-impedance analog switch circuits are proposed. The switch element is a single MOSFET, and constant-impedance operation is obtained using simple circuits to adjust the gate and bulk voltages relative to the switched signal. Low-voltage (1-volt) operation is made feasible...

  16. Caffeine improves anticipatory processes in task switching

    NARCIS (Netherlands)

    Tieges, Zoe; Snel, Jan; Kok, Albert; Wijnen, Jasper G.; Lorist, Monicque M.; Ridderinkhof, K. Richard

    We studied the effects of moderate amounts of caffeine on task switching and task maintenance using mixed-task (AABB) blocks, in which participants alternated predictably between two tasks, and single-task (AAAA, BBBB) blocks. Switch costs refer to longer reaction times (RT) on task switch trials

  17. Switching antidepressants | Outhoff | South African Family Practice

    African Journals Online (AJOL)

    ... worsening depression or unpleasant discontinuation reactions. Switching strategies to minimise these risks include immediate switching, cross-tapering or incorporating a washout period. Immediate switching is generally possible when substituting a selective serotonin reuptake inhibitor or a serotonin and noradrenaline ...

  18. 47 CFR 69.106 - Local switching.

    Science.gov (United States)

    2010-10-01

    ... foreign services that use local exchange switching facilities. (c) If end users of an interstate or... local exchange carriers shall establish rate elements for local switching as follows: (1) Price cap... use local exchange switching facilities for the provision of interstate or foreign services. The...

  19. Degree of Conversational Code-Switching Enhances Verbal Task Switching in Cantonese-English Bilinguals

    Science.gov (United States)

    Yim, Odilia; Bialystok, Ellen

    2012-01-01

    The study examined individual differences in code-switching to determine the relationship between code-switching frequency and performance in verbal and non-verbal task switching. Seventy-eight Cantonese-English bilinguals completed a semi-structured conversation to quantify natural code-switching, a verbal fluency task requiring language…

  20. Large area electron beam diode development

    International Nuclear Information System (INIS)

    Helava, H.; Gilman, C.M.; Stringfield, R.M.; Young, T.

    1983-01-01

    A large area annular electron beam diode has been tested at Physics International Co. on the multi-terawatt PITHON generator. A twelve element post hole convolute converted the coaxial MITL into a triaxial arrangement of anode current return structures both inside and outside the cathode structure. The presence of both inner and outer current return paths provide magnetic pressure balance for the beam, as determined by diode current measurements. X-ray pinhole photographs indicated uniform emission with intensity maxima between the post positions. Current losses in the post hole region were negligible, as evidenced by the absence of damage to the aluminum hardware. Radial electron flow near the cathode ring however did damage the inner anode cylinder between the post positions. Cutting away these regions prevented further damage of the transmission lines

  1. Flexoelectric MEMS: towards an electromechanical strain diode

    Science.gov (United States)

    Bhaskar, U. K.; Banerjee, N.; Abdollahi, A.; Solanas, E.; Rijnders, G.; Catalan, G.

    2016-01-01

    Piezoelectricity and flexoelectricity are two independent but not incompatible forms of electromechanical response exhibited by nanoscale ferroelectrics. Here, we show that flexoelectricity can either enhance or suppress the piezoelectric response of the cantilever depending on the ferroelectric polarity and lead to a diode-like asymmetric (two-state) electromechanical response.Piezoelectricity and flexoelectricity are two independent but not incompatible forms of electromechanical response exhibited by nanoscale ferroelectrics. Here, we show that flexoelectricity can either enhance or suppress the piezoelectric response of the cantilever depending on the ferroelectric polarity and lead to a diode-like asymmetric (two-state) electromechanical response. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06514c

  2. Diode line scanner for beam diagnostics

    International Nuclear Information System (INIS)

    Gustov, S.A.

    1987-01-01

    The device-scanning diode line is described. It is applied for beam profile measuring with space precision better than ± 0.5 mm and with discreteness of 3 mm along Y-axis and 0.25 mm along X-axis. The device is easy in construction, reliable and has a small time of information acquisition (2-5 min). The working range is from 100 to 10 6 rad/min (10 6 -10 10 part/mm 2 /s for 660 MeV protons). Radioresistance is 10 7 rad. The device can be applied for precise beam line element tuning at beam transporting and emittance measuring. The fixed diode line (a simplified device version) has smaller dimensions and smaller time of data acquisition (2-5 s). It is applied for quick preliminary beamline tuning. The flowsheet and different variants of data representation on beam profile are given

  3. IGBT Switching Characteristic Curve Embedded Half-Bridge MMC Modelling and Real Time Simulation Realization

    Science.gov (United States)

    Zhengang, Lu; Hongyang, Yu; Xi, Yang

    2017-05-01

    The Modular Multilevel Converter (MMC) is one of the most attractive topologies in recent years for medium or high voltage industrial applications, such as high voltage dc transmission (HVDC) and medium voltage varying speed motor drive. The wide adoption of MMCs in industry is mainly due to its flexible expandability, transformer-less configuration, common dc bus, high reliability from redundancy, and so on. But, when the sub module number of MMC is more, the test of MMC controller will cost more time and effort. Hardware in the loop test based on real time simulator will save a lot of time and money caused by the MMC test. And due to the flexible of HIL, it becomes more and more popular in the industry area. The MMC modelling method remains an important issue for the MMC HIL test. Specifically, the VSC model should realistically reflect the nonlinear device switching characteristics, switching and conduction losses, tailing current, and diode reverse recovery behaviour of a realistic converter. In this paper, an IGBT switching characteristic curve embedded half-bridge MMC modelling method is proposed. This method is based on the switching curve referring and sample circuit calculation, and it is sample for implementation. Based on the proposed method, a FPGA real time simulation is carried out with 200ns sample time. The real time simulation results show the proposed method is correct.

  4. Solid State Switch Application for the LHC Extraction Kicker Pulse Generator

    CERN Document Server

    Carlier, E; Jansson, U; Schlaug, M; Schröder, G; Vossenberg, Eugène B

    1996-01-01

    A semiconductor solid state switch has been constructed and tested in the prototype extraction kicker pulse generator of CERN's Large Hadron Collider (LHC) [1]. The switch is made of 10 modified 4.5 kV, 66 mm symmetric GTO's (also called FHCT-Fast High Current Thyristor), connected in series. It holds off a d.c. voltage of 30 kV and conducts a 5 µs half-sine wave current of 20 kA with an initial di/dt of 10 kA/µs. Major advantages of the switch are the extremely low self-firing hazard, no power consumption during the ready-to-go status, instantaneous availability, simple condition control, very low noise emission during soft turn-on switching and easy maintenance. However, the inherent soft, relatively slow turn-on time is a non negligible part of the required rise time and this involves adaptation of generator components. A dynamic current range of 16 is achieved with variations in rise time, which stay within acceptable limits. Important generator improvements have been made with the series diodes and fre...

  5. Compact self-Q-switched Tm:YLF laser at 1.91 μm

    Science.gov (United States)

    Zhang, B.; Li, L.; He, C. J.; Tian, F. J.; Yang, X. T.; Cui, J. H.; Zhang, J. Z.; Sun, W. M.

    2018-03-01

    We report self-Q-switching operation in a diode-pumped Tm:YLF bulk laser by exploiting saturable re-absorption under the quasi-three-level regime. Robust self-Q-switched pulse output at 1.91 μm in fundamental mode is demonstrated experimentally with 1.5 at.% doped Tm:YLF crystal. At maximum absorbed pump power of 4.5 W, the average output power and pulse energy are obtained as high as 610 mW and 29 μJ, respectively, with the corresponding slope efficiency of 22%. Pulse repetition rate is tunable in the range of 3-21 kHz with changing the pump power. The dynamics of self-Q-switching of Tm:YLF laser are discussed with the help of a rate equation model showing good agreement with the experiment. The compact self-Q-switched laser near 2 μm has potential application in laser radar systems for accurate wind velocity measurements.

  6. High-performance single nanowire tunnel diodes.

    Science.gov (United States)

    Wallentin, Jesper; Persson, Johan M; Wagner, Jakob B; Samuelson, Lars; Deppert, Knut; Borgström, Magnus T

    2010-03-10

    We demonstrate single nanowire tunnel diodes with room temperature peak current densities of up to 329 A/cm(2). Despite the large surface to volume ratio of the type-II InP-GaAs axial heterostructure nanowires, we measure peak to valley current ratios (PVCR) of up to 8.2 at room temperature and 27.6 at liquid helium temperature. These sub-100-nm-diameter structures are promising components for solar cells as well as electronic applications.

  7. Mechanism of formation of Schottky diodes

    International Nuclear Information System (INIS)

    Ponpon, J.P.; Siffert, P.

    1976-01-01

    The formation of the potential barrier at the metal-silicon contact has been investigated. Special emphazis was given to the study of ageing of gold-N type silicon Schottky diodes, showing that their electrical properties are directly correlated to oxygen diffusion through the metal. A phenomenological model based on the behavior of oxygen with respect to the metal involved is proposed to describe the ageing for any metal deposited on N or P type silicon

  8. An All-Silicon Passive Optical Diode

    OpenAIRE

    Fan, Li; Wang, Jian; Varghese, Leo T.; Shen, Hao; Niu, Ben; Xuan, Yi; Weiner, Andrew M.; Qi, Minghao

    2011-01-01

    A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input pow...

  9. Diode having trenches in a semiconductor region

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, Tomas Apostol; Lu, Bin; Matioli, Elison de Nazareth

    2016-03-22

    An electrode structure is described in which conductive regions are recessed into a semiconductor region. Trenches may be formed in a semiconductor region, such that conductive regions can be formed in the trenches. The electrode structure may be used in semiconductor devices such as field effect transistors or diodes. Nitride-based power semiconductor devices are described including such an electrode structure, which can reduce leakage current and otherwise improve performance.

  10. GaN nanowire Schottky barrier diodes

    OpenAIRE

    Sabui, Gourab; Zubialevich, Vitaly Z.; White, Mary; Pampili, Pietro; Parbrook, Peter J.; McLaren, Mathew; Arredondo-Arechavala, Miryam; Shen, Z. John

    2017-01-01

    A new concept of vertical gallium nitride (GaN) Schottky barrier diode based on nanowire (NW) structures and the principle of dielectric REduced SURface Field (RESURF) is proposed in this paper. High-threading dislocation density in GaN epitaxy grown on foreign substrates has hindered the development and commercialization of vertical GaN power devices. The proposed NW structure, previously explored for LEDs offers an opportunity to reduce defect density and fabricate low cost vertical GaN pow...

  11. Phosphorescent Nanocluster Light-Emitting Diodes.

    Science.gov (United States)

    Kuttipillai, Padmanaban S; Zhao, Yimu; Traverse, Christopher J; Staples, Richard J; Levine, Benjamin G; Lunt, Richard R

    2016-01-13

    Devices utilizing an entirely new class of earth abundant, inexpensive phosphorescent emitters based on metal-halide nanoclusters are reported. Light-emitting diodes with tunable performance are demonstrated by varying cation substitution to these nanoclusters. Theoretical calculations provide insight about the nature of the phosphorescent emitting states, which involves a strong pseudo-Jahn-Teller distortion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Electronic logic to enhance switch reliability in detecting openings and closures of redundant switches

    Science.gov (United States)

    Cooper, James A.

    1986-01-01

    A logic circuit is used to enhance redundant switch reliability. Two or more switches are monitored for logical high or low output. The output for the logic circuit produces a redundant and failsafe representation of the switch outputs. When both switch outputs are high, the output is high. Similarly, when both switch outputs are low, the logic circuit's output is low. When the output states of the two switches do not agree, the circuit resolves the conflict by memorizing the last output state which both switches were simultaneously in and produces the logical complement of this output state. Thus, the logic circuit of the present invention allows the redundant switches to be treated as if they were in parallel when the switches are open and as if they were in series when the switches are closed. A failsafe system having maximum reliability is thereby produced.

  13. Influence of the laser-diode temperature on crystal absorption and ...

    Indian Academy of Sciences (India)

    drive current increases, the peak emission wavelength of the diode array can be expected to change. In addition, individual diodes may exhibit variation in the thermal resistance between the diode junction and the heat sink. This would cause differential heating be- tween the individual diodes. Thus, as the diode drives ...

  14. Diode-laser-illuminated automotive lamp systems

    Science.gov (United States)

    Marinelli, Michael A.; Remillard, Jeffrey T.

    1998-05-01

    We have utilized the high brightness of state-of-the-art diode laser sources, and a variety of emerging optical technologies to develop a new class of thin, uniquely styled automotive brake and signal lamps. Using optics based on thin (5 mm) plastic sheets, these lamps provide appearance and functional advantages not attainable with traditional automotive lighting systems. The light is coupled into the sheets using a 1 mm diameter glass fiber, and manipulated using refraction and reflection from edges, surfaces, and shaped cut-outs. Light can be extracted with an efficiency of approximately 50% and formed into a luminance distribution that meets the Society of Automotive Engineers (SAE) photometric requirements. Prototype lamps using these optics have been constructed and are less than one inch in thickness. Thin lamps reduce sheet metal costs, complexity, material usage, weight, and allow for increased trunk volume. In addition, these optics enhance lamp design flexibility. When the lamps are not energized, they can appear body colored, and when lighted, the brightness distribution across the lamp can be uniform or structured. A diode laser based brake lamp consumes seven times less electrical power than one using an incandescent source and has instant on capability. Also, diode lasers have the potential to be 10-year/150,000 mile light sources.

  15. Performance measurements of hybrid PIN diode arrays

    International Nuclear Information System (INIS)

    Jernigan, J.G.; Arens, J.F.; Collins, T.; Herring, J.; Shapiro, S.L.; Wilburn, C.D.

    1990-05-01

    We report on the successful effort to develop hybrid PIN diode arrays and to demonstrate their potential as components of vertex detectors. Hybrid pixel arrays have been fabricated by the Hughes Aircraft Co. by bump bonding readout chips developed by Hughes to an array of PIN diodes manufactured by Micron Semiconductor Inc. These hybrid pixel arrays were constructed in two configurations. One array format having 10 x 64 pixels, each 120 μm square, and the other format having 256 x 256 pixels, each 30 μm square. In both cases, the thickness of the PIN diode layer is 300 μm. Measurements of detector performance show that excellent position resolution can be achieved by interpolation. By determining the centroid of the charge cloud which spreads charge into a number of neighboring pixels, a spatial resolution of a few microns has been attained. The noise has been measured to be about 300 electrons (rms) at room temperature, as expected from KTC and dark current considerations, yielding a signal-to-noise ratio of about 100 for minimum ionizing particles. 4 refs., 13 figs

  16. Shape memory thermal conduction switch

    Science.gov (United States)

    Vaidyanathan, Rajan (Inventor); Krishnan, Vinu (Inventor); Notardonato, William U. (Inventor)

    2010-01-01

    A thermal conduction switch includes a thermally-conductive first member having a first thermal contacting structure for securing the first member as a stationary member to a thermally regulated body or a body requiring thermal regulation. A movable thermally-conductive second member has a second thermal contacting surface. A thermally conductive coupler is interposed between the first member and the second member for thermally coupling the first member to the second member. At least one control spring is coupled between the first member and the second member. The control spring includes a NiTiFe comprising shape memory (SM) material that provides a phase change temperature <273 K, a transformation range <40 K, and a hysteresis of <10 K. A bias spring is between the first member and the second member. At the phase change the switch provides a distance change (displacement) between first and second member by at least 1 mm, such as 2 to 4 mm.

  17. Switch for Good Community Program

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Tabitha [Balfour Beatty Military Housing Management LLC, Newtown Square, PA (United States); Amran, Martha [WattzOn, Inc., Mountain View, CA (United States)

    2013-11-19

    Switch4Good is an energy-savings program that helps residents reduce consumption from behavior changes; it was co-developed by Balfour Beatty Military Housing Management (BB) and WattzOn in Phase I of this grant. The program was offered at 11 Navy bases. Three customer engagement strategies were evaluated, and it was found that Digital Nudges (a combination of monthly consumption statements with frequent messaging via text or email) was most cost-effective. The program was delivered on-time and on-budget, and its success is based on the teamwork of local BB staff and the WattzOn team. The following graphic shows Switch4Good “by the numbers”, e.g. the scale of operations achieved during Phase I.

  18. Negation switching invariant signed graphs

    Directory of Open Access Journals (Sweden)

    Deepa Sinha

    2014-04-01

    Full Text Available A signed graph (or, $sigraph$ in short is a graph G in which each edge x carries a value $\\sigma(x \\in \\{-, +\\}$ called its sign. Given a sigraph S, the negation $\\eta(S$ of the sigraph S is a sigraph obtained from S by reversing the sign of every edge of S. Two sigraphs $S_{1}$ and $S_{2}$ on the same underlying graph are switching equivalent if it is possible to assign signs `+' (`plus' or `-' (`minus' to vertices of $S_{1}$ such that by reversing the sign of each of its edges that has received opposite signs at its ends, one obtains $S_{2}$. In this paper, we characterize sigraphs which are negation switching invariant and also see for what sigraphs, S and $\\eta (S$ are signed isomorphic.

  19. Large aperture optical switching devices

    International Nuclear Information System (INIS)

    Goldhar, J.; Henesian, M.A.

    1983-01-01

    We have developed a new approach to constructing large aperture optical switches for next generation inertial confinement fusion lasers. A transparent plasma electrode formed in low pressure ionized gas acts as a conductive coating to allow the uniform charging of the optical faces of an electro-optic material. In this manner large electric fields can be applied longitudinally to large aperture, high aspect ratio Pockels cells. We propose a four-electrode geometry to create the necessary high conductivity plasma sheets, and have demonstrated fast (less than 10 nsec) switching in a 5x5 cm aperture KD*P Pockels cell with such a design. Detaid modelling of Pockels cell performance with plasma electrodes has been carried out for 15 and 30 cm aperture designs

  20. Resistive Switching Assisted by Noise

    OpenAIRE

    Patterson, G. A.; Fierens, P. I.; Grosz, D. F.

    2013-01-01

    We extend results by Stotland and Di Ventra on the phenomenon of resistive switching aided by noise. We further the analysis of the mechanism underlying the beneficial role of noise and study the EPIR (Electrical Pulse Induced Resistance) ratio dependence with noise power. In the case of internal noise we find an optimal range where the EPIR ratio is both maximized and independent of the preceding resistive state. However, when external noise is considered no beneficial effect is observed.

  1. Switching strategies to optimize search

    Science.gov (United States)

    Shlesinger, Michael F.

    2016-03-01

    Search strategies are explored when the search time is fixed, success is probabilistic and the estimate for success can diminish with time if there is not a successful result. Under the time constraint the problem is to find the optimal time to switch a search strategy or search location. Several variables are taken into account, including cost, gain, rate of success if a target is present and the probability that a target is present.

  2. Analytic model of Applied-B ion diode impedance behavior

    International Nuclear Information System (INIS)

    Miller, P.A.; Mendel, C.W. Jr.

    1987-01-01

    An empirical analysis of impedance data from Applied-B ion diodes used in seven inertial confinement fusion research experiments was published recently. The diodes all operated with impedance values well below the Child's-law value. The analysis uncovered an unusual unifying relationship among data from the different experiments. The analysis suggested that closure of the anode-cathode gap by electrode plasma was not a dominant factor in the experiments, but was not able to elaborate the underlying physics. Here we present a new analytic model of Applied-B ion diodes coupled to accelerators. A critical feature of the diode model is based on magnetic insulation theory. The model successfully describes impedance behavior of these diodes and supports stimulating new viewpoints of the physics of Applied-B ion diode operation

  3. A DTC Algorithm for Induction Motor Drives with 3-level Diode-Clamped Inverters

    Directory of Open Access Journals (Sweden)

    M. Cirrincione

    2005-12-01

    Full Text Available This paper presents a novel Direct Torque Control (DTC algorithm for induction motor electrical drives supplied by 3-level diode clamped inverters. It is the natural extension of the classic Switching Table (ST based DTC, modified for a 3-level inverter supply. It presents also a very simple algorithm for the minimization of the capacitor voltage ripple. Results obtained with numerical simulations show that the employment of a 3-level inverter in such a control scheme permits to obtain the same dynamical performances as those obtained with a 2-level inverter with resulting lower torque and flux ripples as well as a lower harmonic content in the stator voltages and currents. Some considerations about the consequent benefits as for EMC of this drive are also presented.

  4. High-average-power diode-end-pumped intracavity-doubled Nd:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Honea, E.C.; Ebbers, C.A.; Beach, R.J.; Speth, J.A.; Emanuel, M.S> ; Skidmore, J.A.; Payne, S.A.

    1998-02-12

    A compact diode-pumped ND:YAG laser was frequency-doubled to 0.532 {mu}m with an intracavity KTP or LBO crystal using a `V` cavity configuration. Two acousto-optic Q-switches were employed at repetition rates of 10-30 kHz. Dichroic fold and end mirrors were used to output two beams with up to 140 W of 0.532 {mu}m power using KTP and 116 W using LBO as the frequency doubling crystal. This corresponds to 66% of the maximum output power at 1.064 {mu}m obtained with an optimized output coupler reflectivity. The minimum output pulse duration varied with repetition rate from 90 to 130 ns. The multimode output beam had a smooth profile and a beam quality of M{sup 2} = 5 1.

  5. Strategies to Achieve High-Performance White Organic Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Lirong Zhang

    2017-12-01

    Full Text Available As one of the most promising technologies for next-generation lighting and displays, white organic light-emitting diodes (WOLEDs have received enormous worldwide interest due to their outstanding properties, including high efficiency, bright luminance, wide viewing angle, fast switching, lower power consumption, ultralight and ultrathin characteristics, and flexibility. In this invited review, the main parameters which are used to characterize the performance of WOLEDs are introduced. Subsequently, the state-of-the-art strategies to achieve high-performance WOLEDs in recent years are summarized. Specifically, the manipulation of charges and excitons distribution in the four types of WOLEDs (fluorescent WOLEDs, phosphorescent WOLEDs, thermally activated delayed fluorescent WOLEDs, and fluorescent/phosphorescent hybrid WOLEDs are comprehensively highlighted. Moreover, doping-free WOLEDs are described. Finally, issues and ways to further enhance the performance of WOLEDs are briefly clarified.

  6. Flexible one diode-one phase change memory array enabled by block copolymer self-assembly.

    Science.gov (United States)

    Mun, Beom Ho; You, Byoung Kuk; Yang, Se Ryeun; Yoo, Hyeon Gyun; Kim, Jong Min; Park, Woon Ik; Yin, You; Byun, Myunghwan; Jung, Yeon Sik; Lee, Keon Jae

    2015-04-28

    Flexible memory is the fundamental component for data processing, storage, and radio frequency communication in flexible electronic systems. Among several emerging memory technologies, phase-change random-access memory (PRAM) is one of the strongest candidate for next-generation nonvolatile memories due to its remarkable merits of large cycling endurance, high speed, and excellent scalability. Although there are a few approaches for flexible phase-change memory (PCM), high reset current is the biggest obstacle for the practical operation of flexible PCM devices. In this paper, we report a flexible PCM realized by incorporating nanoinsulators derived from a Si-containing block copolymer (BCP) to significantly lower the operating current of the flexible memory formed on plastic substrate. The reduction of thermal stress by BCP nanostructures enables the reliable operation of flexible PCM devices integrated with ultrathin flexible diodes during more than 100 switching cycles and 1000 bending cycles.

  7. Spectral matching technology for light-emitting diode-based jaundice photodynamic therapy device

    Science.gov (United States)

    Gan, Ru-ting; Guo, Zhen-ning; Lin, Jie-ben

    2015-02-01

    The objective of this paper is to obtain the spectrum of light-emitting diode (LED)-based jaundice photodynamic therapy device (JPTD), the bilirubin absorption spectrum in vivo was regarded as target spectrum. According to the spectral constructing theory, a simple genetic algorithm as the spectral matching algorithm was first proposed in this study. The optimal combination ratios of LEDs were obtained, and the required LEDs number was then calculated. Meanwhile, the algorithm was compared with the existing spectral matching algorithms. The results show that this algorithm runs faster with higher efficiency, the switching time consumed is 2.06 s, and the fitting spectrum is very similar to the target spectrum with 98.15% matching degree. Thus, blue LED-based JPTD can replace traditional blue fluorescent tube, the spectral matching technology that has been put forward can be applied to the light source spectral matching for jaundice photodynamic therapy and other medical phototherapy.

  8. Switchable diode effect in oxygen vacancy-modulated SrTiO{sub 3} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Xinqiang; Shuai, Yao; Wu, Chuangui; Luo, Wenbo; Sun, Xiangyu; Zeng, Huizhong; Bai, Xiaoyuan; Gong, Chaoguan; Jian, Ke; Zhang, Wanli [University of Electronic Science and Technology of China, State Key Laboratory of Electronic Thin Films and Integrated Devices, Chengdu (China); Zhang, Lu; Guo, Hongliang [University of Electronic Science and Technology of China, The Center for Robotics, Chengdu (China); Tian, Benlang [26th Institute of China Electronics Technology Group Corporation, Chongqing (China)

    2017-09-15

    SrTiO{sub 3} (STO) single crystal wafer was annealed in vacuum, and co-planar metal-insulator-metal structure of Pt/Ti/STO/Ti/Pt were formed by sputtering Pt/Ti electrodes onto the surface of STO after annealing. The forming-free resistive switching behavior with self-compliance property was observed in the sample. The sample showed switchable diode effect, which is explained by a simple model that redistribution of oxygen vacancies (OVs) under the external electric field results in the formation of n-n{sup +} junction or n{sup +}-n junction (n donated n-type semiconductor; n{sup +} donated heavily doped n-type semiconductor). The self-compliance property is also interpreted by the formation of n-n{sup +}/n{sup +}-n junction caused by the migration of the OVs under the electric field. (orig.)

  9. Active Device-Less Voltage Equalization Charger Using Capacitors, Diodes, and an AC Power Source

    Science.gov (United States)

    Uno, Masatoshi; Tanaka, Koji

    Conventional cell/module voltage equalizers or equalization chargers based on traditional dc-dc converters require numerous switches or transformers as the number of series connections increases; therefore, their cost and complexity tend to increase and their reliability decreases as the number of connections increases. This paper proposes a novel voltage equalization charger that consists only of passive components such as capacitors, diodes, and a transformer. The fundamental operating principle, major features, and derivation of equivalent dc circuits are presented. A symmetrical configuration is also proposed to mitigate the RMS current flowing through energy storage cells in the charging process. Simulations and experimental charging and cycle tests were performed on series-connected electric double-layer capacitor modules to demonstrate the equalization performance. The experimental and simulation results were in good agreement, and the voltage imbalances were gradually eliminated as time elapsed even during charge-discharge cycling.

  10. Molecular wires, switches and memories

    Science.gov (United States)

    Chen, Jia

    Molecular electronics, an emerging field, makes it possible to build individual molecules capable of performing functions identical or analogous to present- day conductors, switches, or memories. These individual molecules, with a nano-meter scale characteristic length, can be designed and chemically synthesized with specific atoms, geometries and charge distribution. This thesis focuses on the design, and measurements of molecular wires, and related strategically engineered structures-molecular switches and memories. The experimental system relies on a thermodynamically driven self-assembling process to attach molecules onto substrate surfaces without intervention from outside. The following topics will be discussed: directed nanoscale manipulation of self-assembled molecules using scanning tunneling microscope; investigation on through-bond transport of nanoscale symmetric metal/conjugated self- assembled monolayers (SAM)/metal junctions, where non- Ohmic thermionic emission was observed to be the dominant process, with isocyanide-Pd contacts showing the lowest thermionic barrier of 0.22 eV; the first realization of robust and large reversible switching behavior in an electronic device that utilizes molecules containing redox centers as the active component, exhibiting negative differential resistance (NDR) and large on-off peak-to-valley ratio (PVR); observation of erasable storage of higher conductivity states in these redox- center containing molecular devices, and demonstration of a two-terminal electronically programmable and erasable molecular memory cell with long bit retention time.

  11. Analytical Performance Evaluation of Different Switch Solutions

    Directory of Open Access Journals (Sweden)

    Francisco Sans

    2013-01-01

    Full Text Available The virtualization of the network access layer has opened new doors in how we perceive networks. With this virtualization of the network, it is possible to transform a regular PC with several network interface cards into a switch. PC-based switches are becoming an alternative to off-the-shelf switches, since they are cheaper. For this reason, it is important to evaluate the performance of PC-based switches. In this paper, we present a performance evaluation of two PC-based switches, using Open vSwitch and LiSA, and compare their performance with an off-the-shelf Cisco switch. The RTT, throughput, and fairness for UDP are measured for both Ethernet and Fast Ethernet technologies. From this research, we can conclude that the Cisco switch presents the best performance, and both PC-based switches have similar performance. Between Open vSwitch and LiSA, Open vSwitch represents a better choice since it has more features and is currently actively developed.

  12. Streamer model for high voltage water switches

    International Nuclear Information System (INIS)

    Sazama, F.J.; Kenyon, V.L. III

    1979-01-01

    An electrical switch model for high voltage water switches has been developed which predicts streamer-switching effects that correlate well with water-switch data from Casino over the past four years and with switch data from recent Aurora/AMP experiments. Preclosure rounding and postclosure resistive damping of pulseforming line voltage waveforms are explained in terms of spatially-extensive, capacitive-coupling of the conducting streamers as they propagate across the gap and in terms of time-dependent streamer resistance and inductance. The arc resistance of the Casino water switch and of a gas switch under test on Casino was determined by computer fit to be 0.5 +- 0.1 ohms and 0.3 +- 0.06 ohms respectively, during the time of peak current in the power pulse. Energy lost in the water switch during the first pulse is 18% of that stored in the pulseforming line while similar energy lost in the gas switch is 11%. The model is described, computer transient analyses are compared with observed water and gas switch data and the results - switch resistance, inductance and energy loss during the primary power pulse - are presented

  13. Synchronization in complex networks with switching topology

    International Nuclear Information System (INIS)

    Wang, Lei; Wang, Qing-guo

    2011-01-01

    This Letter investigates synchronization issues of complex dynamical networks with switching topology. By constructing a common Lyapunov function, we show that local and global synchronization for a linearly coupled network with switching topology can be evaluated by the time average of second smallest eigenvalues corresponding to the Laplacians of switching topology. This result is quite powerful and can be further used to explore various switching cases for complex dynamical networks. Numerical simulations illustrate the effectiveness of the obtained results in the end. -- Highlights: → Synchronization of complex networks with switching topology is investigated. → A common Lyapunov function is established for synchronization of switching network. → The common Lyapunov function is not necessary to monotonically decrease with time. → Synchronization is determined by the second smallest eigenvalue of its Laplacian. → Synchronization criterion can be used to investigate various switching cases.

  14. Pinning Synchronization of Switched Complex Dynamical Networks

    Directory of Open Access Journals (Sweden)

    Liming Du

    2015-01-01

    Full Text Available Network topology and node dynamics play a key role in forming synchronization of complex networks. Unfortunately there is no effective synchronization criterion for pinning synchronization of complex dynamical networks with switching topology. In this paper, pinning synchronization of complex dynamical networks with switching topology is studied. Two basic problems are considered: one is pinning synchronization of switched complex networks under arbitrary switching; the other is pinning synchronization of switched complex networks by design of switching when synchronization cannot achieved by using any individual connection topology alone. For the two problems, common Lyapunov function method and single Lyapunov function method are used respectively, some global synchronization criteria are proposed and the designed switching law is given. Finally, simulation results verify the validity of the results.

  15. High-power laser diodes at various wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Emanuel, M.A.

    1997-02-19

    High power laser diodes at various wavelengths are described. First, performance and reliability of an optimized large transverse mode diode structure at 808 and 941 nm are presented. Next, data are presented on a 9.5 kW peak power array at 900 nm having a narrow emission bandwidth suitable for pumping Yb:S-FAP laser materials. Finally, results on a fiber-coupled laser diode array at {approx}730 nm are presented.

  16. Noise equivalent circuit of a semiconductor laser diode

    OpenAIRE

    Harder, Christoph; Katz, Joseph; Margalit, S.; Shacham, J.; Yariv, A.

    1982-01-01

    The noise equivalent circuit of a semiconductor laser diode is derived from the rate equations including Langevin noise sources. This equivalent circuit allows a straightforward calculation of the noise and modulation characteristics of a laser diode combined with electronic components. The intrinsic junction voltage noise spectrum and the light intensity fluctuation of a current driven laser diode are calculated as a function of bias current and frequency.

  17. Single cavity Fabry-Perot modulator enhancements and integrated vertically coupled cavity light-emitting diode

    Science.gov (United States)

    Liu, Daxin

    Fabry-Perot modulators with Multi-Quantum Wells (MQWs) cavities have been studied with great interest during recent years. Usually operating as intensity modulators, these devices have very high modulation contrast ratios, can be operated at very high speed, can be easily made into two dimensional arrays and can be integrated with silicon ICs. They are thus very promising for optical interconnects, optical switching and image processing applications. But before these modulators are to be used in real applications, there are several issues that need to be solved, including the parasitic phase modulation, the bandwidth of such modulators and the alignment of modulator operation wavelength with the wavelength of lasers or light emitting diodes. In this work, the phase properties of Fabry-Perot reflection modulators will be discussed first and an experimental method using a modified Michelson interferometer to characterize the exact phase change will be demonstrated. It is demonstrated that the phase of the reflection light beam from a Fabry-Perot modulator is determined not only by the refractive index change inside the cavity but also by the absorption change inside the cavity. With the purpose of expanding the limited bandwidth of such modulator, devices with short passive cavities are designed and fabricated, the results are described and trade-offs between modulation depth and bandwidth will be discussed. In order to solve the problem of alignment and expand the functionality of Fabry-Perot modulators further, vertically coupled cavity devices with each cavity being electrically controlled independently have been developed. Both a coupled cavity modulator and an integrated light emitting diode with a transmission Fabry-Perot modulator are demonstrated; the first device enhances the modulation bandwidth while the second device has the potential of combining the advantage of high speed operation of MQWs modulators with the long lifetime and low cost of light

  18. Fast recovery SOI PiN diode with multiple trenches

    Science.gov (United States)

    Zhang, Long; Zhu, Jing; Zhao, Minna; Ding, Desheng; Chen, Jian; Sun, Weifeng

    2017-11-01

    In this paper, a 500V SOI PiN lateral diode is proposed and investigated by simulations and experiments. The proposed structure features multiple deep-oxide trenches (MDOT) arranged in the silicon region. Two DOTs (T1 and T2) locating in the i-layer help to block the cathode-anode voltage (VCA), allowing the diode to shorten its i-layer length. With a similar breakdown voltage (BV) of 560V, the i-layer length is shortened from 47 μm for the conventional diode to 21.9 μm for the proposed MDOT diode. The shortened i-layer leads to a reduced number of stored carriers in the i-layer. Another DOT (T3) is inserted at the anode region of proposed MDOT diode and shorted with P+ anode. T3 acts as a vertical field plate, reshaping the electric potential distribution at the anode region and accelerating the depletion during the reverse recovery process. Thanks to the decreased number of the stored carriers and the accelerated depletion, the reverse recovery time (trr) of the proposed MDOT diode (211 ns) can be decreased by 56.7% compared with the conventional diode (487 ns) at the forward current density of 400 A/cm2 at T = 300 K. The proposed MDOT diode exhibits a better trade-off between forward voltage drop (VF) and reverse recovery time (trr) than the conventional and other reported diodes.

  19. Millimeter-wave diode-grid phase shifters

    Science.gov (United States)

    Lam, Wayne W.; Stolt, Kjell S.; Jou, Christina F.; Luhmann, Neville C., Jr.; Chen, Howard Z.

    1988-05-01

    Monolithic diode grids have been fabricated on 2-cm square gallium-arsenide wafers with 1600 Schottky-barrier varactor diodes. Shorted diodes are detected with a liquid-crystal technique, and the bad diodes are removed with an ultrasonic probe. A small-aperture reflectometer that uses wavefront division interference was developed to measure the reflection coefficient of the grids. A phase shift of 70 deg with a 7-dB loss was obtained at 93 GHz when the bias on the diode grid was changed from -3 V to 1 V. A simple transmission-line grid model, together with the measured low-frequency parameters for the diodes, was shown to predict the measured performance over the entire capacitive bias range of the diodes, as well as over the complete reactive tuning range provided by a reflector behind the grid, and over a wide range of frequencies from 33 GHz to 141 GHz. This shows that the transmission-line model and the measured low-frequency diode parameters can be used to design an electronic beam-steering array and to predict its performance. An electronic beam-steering array made of a pair of grids using state-of-the-art diodes with 5-ohm series resistances would have a loss of 1.4 dB at 90 GHz.

  20. Diode parameter extraction by a linear cofactor difference operation method

    Energy Technology Data Exchange (ETDEWEB)

    Ma Chenyue; He Jin; Lin Xinnan [Shenzhen SOC Key Laboratory of Peking University, PKU-HKUST Shenzhen Institute, Hi-Tech Industrial Park South, Shenzhen 518057 (China); Zhang Chenfei; Wang Hao [Key Laboratory of Integrated Microsystems, School of Computer and Information Engineering, Peking University, Shenzhen Graduate School, Shenzhen 518055 (China); Mansun Chan, E-mail: xnlin@szpku.edu.cn, E-mail: hejin@szpku.edu.cn [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Kowloon (Hong Kong)

    2010-11-15

    The linear cofactor difference operator (LCDO) method, a direct parameter extraction method for general diodes, is presented. With the developed LCDO method, the extreme spectral characteristic of the diode voltage-current curves is revealed, and its extreme positions are related to the diode characteristic parameters directly. The method is applied to diodes with different sizes and temperatures, and the related characteristic parameters, such as reverse saturation current, series resistance and non-ideality factor, are extracted directly. The extraction result shows good agreement with the experimental data.

  1. Vertical Silicon Nanowire Diode with Nickel Silicide Induced Dopant Segregation

    Science.gov (United States)

    Lu, Weijie; Pey, Kin Leong; Wang, Xinpeng; Li, Xiang; Chen, Zhixian; Navab, Singh; Chew Leong, Kam; Lip Gan, Chee; Tan, Chuan Seng

    2012-11-01

    Dopant segregated Schottky barrier (DSSB) and Schottky barrier (SB) vertical silicon nanowire (VSiNW) diodes were fabricated using industry complemetary metal oxide semiconductor field effect transistor (CMOS) processes to investigate the effects of segregated dopants at the silicide/silicon interface and different annealing steps on nickel silicide formation in the DSSB VSiNW diodes. With segregated dopants at the silicide/silicon interface, VSiNW diodes showed higher on-current, due to an enhanced carrier tunneling, and much lower off-current. This can be attributed to the altered energy bands caused by the accumulated Arsenic dopants at the interface. Moreover, DSSB VSiNW diodes also presented ideality factor much closer to unity and exhibited lower electron Schottky barrier height (ΦBn) than SB VSiNW diodes. This proved that interfacial accumulated dopants could impede the inhomogeneous nature of the Schottky diodes and simultaneously, minimize the effect of Fermi level pinning and ionization of surface defect states. Comparing the impact of different silicide formation annealing sequence using DSSB VSiNW diodes, the 2-step anneal process reduces the silicide intrusion length within the SiNW by ˜5× and the silicide interface was smooth along the (100) direction. Furthermore, the 2-step DSSB VSiNW diode also exhibited much lower leakage current and an ideality factor much closer to unity, as compared to the 1-step DSSB VSiNW diode.

  2. Plasma-filled diode based on the coaxial gun

    Science.gov (United States)

    Zherlitsyn, A. A.; Kovalchuk, B. M.; Pedin, N. N.

    2012-10-01

    The paper presents the results of studies of a coaxial gun for a plasma-filled electron diode. Effects of the discharge channel diameter and gun current on characteristics of the plasma and pulse generated in the diode were investigated. The electron beam with maximum energy of ≥1 MeV at the current of ≈100 kA was obtained in the experiments with a plasma-filled diode. The energy of ≈5 kJ with the peak power of ≥100 GW dissipated in the diode.

  3. Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Pocha, M D; Goddard, L L; Bond, T C; Nikolic, R J; Vernon, S P; Kallman, J S; Behymer, E M

    2007-01-03

    In multisection laser diodes, the amplitude or frequency modulation (AM or FM) efficiency can be improved using the gain lever effect. To study gain lever, InGaAs double quantum well (DQW) edge emitting lasers have been fabricated with integrated passive waveguides and dual sections providing a range of split ratios from 1:1 to 9:1. Both the electrical and the optical gain lever have been examined. An electrical gain lever with greater than 7 dB enhancement of AM efficiency was achieved within the range of appropriate DC biasing currents, but this gain dropped rapidly outside this range. We observed a 4 dB gain in the optical AM efficiency under non-ideal biasing conditions. This value agreed with the measured gain for the electrical AM efficiency under similar conditions. We also examined the gain lever effect under large signal modulation for digital logic switching applications. To get a useful gain lever for optical gain quenched logic, a long control section is needed to preserve the gain lever strength and a long interaction length between the input optical signal and the lasing field of the diode must be provided. The gain lever parameter space has been fully characterized and validated against numerical simulations of a semi-3D hybrid beam propagation method (BPM) model for the coupled electron-photon rate equation. We find that the optical gain lever can be treated using the electrical injection model, once the absorption in the sample is known.

  4. Improved performance in vertical GaN Schottky diode assisted by AlGaN tunneling barrier

    International Nuclear Information System (INIS)

    Cao, Y.; Chu, R.; Li, R.; Chen, M.; Williams, A. J.

    2016-01-01

    In a vertical GaN Schottky barrier diode, the free electron concentration n in the 6-μm-thick drift layer was found to greatly impact the diode reverse leakage current, which increased from 2.1 × 10 −7  A to 3.9 × 10 −4  A as n increased from 7.5 × 10 14  cm −3 to 6.3 × 10 15  cm −3 at a reverse bias of 100 V. By capping the drift layer with an ultrathin 5-nm graded AlGaN layer, reverse leakage was reduced by more than three orders of magnitude with the same n in the drift layer. We attribute this to the increased Schottky barrier height with the AlGaN at the surface. Meanwhile, the polarization field within the graded AlGaN effectively shortened the depletion depth, which led to the formation of tunneling current at a relatively small forward bias. The turn-on voltage in the vertical Schottky diodes was reduced from 0.77 V to 0.67 V—an advantage in reducing conduction loss in power switching applications.

  5. Mechanical switching of ferroelectric domains beyond flexoelectricity

    Science.gov (United States)

    Chen, Weijin; Liu, Jianyi; Ma, Lele; Liu, Linjie; Jiang, G. L.; Zheng, Yue

    2018-02-01

    The resurgence of interest in flexoelectricity has prompted discussions on the feasibility of switching ferroelectric domains 'non-electrically'. In this work, we perform three-dimensional thermodynamic simulations in combination with ab initio calculations and effective Hamiltonian simulations to demonstrate the great effects of surface screening and surface bonding on ferroelectric domain switching triggered by local tip loading. A three-dimensional simulation scheme has been developed to capture the tip-induced domain switching behavior in ferroelectric thin films by adequately taking into account the surface screening effect and surface bonding effect of the ferroelectric film, as well as the finite elastic stiffness of the substrate and the electrode layers. The major findings are as follows. (i) Compared with flexoelectricity, surface effects can be overwhelming and lead to much more efficient mechanical switching caused by tip loading. (ii) The surface-assisted mechanical switching can be bi-directional without the necessity of reversing strain gradients. (iii) A mode transition from local to propagating domain switching occurs when the screening below a critical value. A ripple effect of domain switching appears with the formation of concentric loop domains. (iv) The ripple effect can lead to 'domain interference' and a deterministic writing of confined loop domain patterns by local excitations. Our study reveals the hidden switching mechanisms of ferroelectric domains and the possible roles of surface in mechanical switching. The ripple effect of domain switching, which is believed to be general in dipole systems, broadens our current knowledge of domain engineering.

  6. Unipolar resistive switching in metal oxide/organic semiconductor non-volatile memories as a critical phenomenon

    International Nuclear Information System (INIS)

    Bory, Benjamin F.; Meskers, Stefan C. J.; Rocha, Paulo R. F.; Gomes, Henrique L.; Leeuw, Dago M. de

    2015-01-01

    Diodes incorporating a bilayer of an organic semiconductor and a wide bandgap metal oxide can show unipolar, non-volatile memory behavior after electroforming. The prolonged bias voltage stress induces defects in the metal oxide with an areal density exceeding 10 17  m −2 . We explain the electrical bistability by the coexistence of two thermodynamically stable phases at the interface between an organic semiconductor and metal oxide. One phase contains mainly ionized defects and has a low work function, while the other phase has mainly neutral defects and a high work function. In the diodes, domains of the phase with a low work function constitute current filaments. The phase composition and critical temperature are derived from a 2D Ising model as a function of chemical potential. The model predicts filamentary conduction exhibiting a negative differential resistance and nonvolatile memory behavior. The model is expected to be generally applicable to any bilayer system that shows unipolar resistive switching

  7. Intracavity KTiOAsO4 optical parametric oscillator pumped by an actively Q-switched Nd:YAG laser

    Science.gov (United States)

    Lan, W. X.; Wang, Q. P.; Liu, Z. J.; Zhang, X. Y.; Wan, X. B.; Bai, F.; Shen, H. B.; Lv, G. P.; Jin, G. F.; Tao, X. T.; Sun, Y. X.

    2012-04-01

    A KTiOAsO4 (KTA) intracavity optical parametric oscillator (IOPO) is achieved within a diode end-pumped acousto-optically Q-switched Nd:YAG laser. With a 25-mm-long X-cut KTA crystal, efficient parametric conversions to signal (1535 nm) and idler (3467 nm) waves are realized. At an incident diode power of 14.9 W, the highest output power of 1.83 W including 1.37 W of signal and 0.46 W of idler radiations are obtained at a repetition rate of 40 kHz, corresponding to a total optical-to-optical conversion efficiency of 12.3%. Rate equations model are used to simulate this system, and the theoretical results agree with the experimental ones.

  8. Switching model photovoltaic pumping system

    Science.gov (United States)

    Anis, Wagdy R.; Abdul-Sadek Nour, M.

    Photovoltaic (PV) pumping systems are widely used due to their simplicity, high reliability and low cost. A directly-coupled PV pumping system is the most reliable and least-cost PV system. The d.c. motor-pump group is not, however, working at its optimum operating point. A battery buffered PV pumping system introduces a battery between the PV array and the d.c. motor-pump group to ensure that the motor-pump group is operating at its optimum point. The size of the battery storage depends on system economics. If the battery is fully charged while solar radiation is available, the battery will discharge through the load while the PV array is disconnected. Hence, a power loss takes place. To overcome the above mentioned difficulty, a switched mode PV pumping is proposed. When solar radiation is available and the battery is fully charged, the battery is disconnected and the d.c. motor-pump group is directly coupled to the PV array. To avoid excessive operating voltage for the motor, a part of the PV array is switched off to reduce the voltage. As a result, the energy loss is significantly eliminated. Detailed analysis of the proposed system shows that the discharged water increases by about 10% when compared with a conventional battery-buffered system. The system transient performance just after the switching moment shows that the system returns to a steady state in short period. The variations in the system parameters lie within 1% of the rated values.

  9. Diode laser prostatectomy (VLAP): initial canine evaluation

    Science.gov (United States)

    Kopchok, George E.; Verbin, Chris; Ayres, Bruce; Peng, Shi-Kaung; White, Rodney A.

    1995-05-01

    This study evaluated the acute and chronic effects of diode laser (960 nm) prostatectomy using a Prolase II fiber in a canine model (n equals 5). The laser fiber consists of a 1000 um quartz fiber which reflects a cone of laser energy, at 45 degree(s) to the axis of the fiber, into the prostatic urethra (Visual Laser Ablation of Prostate). Perineal access was used to guide a 15.5 Fr cystoscope to the level of the prostate. Under visual guidance and continual saline irrigation, 60 watts of laser power was delivered for 60 seconds at 3, 9, and 12 o'clock and 30 seconds at the 6 o'clock (posterior) positions for a total energy fluence of 12,600 J. One prostate received an additional 60 second exposure at 3 and 9 o'clock for a total fluence of 19,800 J. The prostates were evaluated at one day (n equals 1) and 8 weeks (n equals 4). The histopathology of laser effects at one day show areas of necrosis with loss of glandular structures and stromal edema. Surrounding this area was a zone of degenerative glandular structures extending up to 17.5 mm (cross sectional diameter). The histopathology of the 8 week laser treated animals demonstrated dilated prostatic urethras with maximum cross- sectional diameter of 23.4 mm (mean equals 18.5 +/- 3.9 mm). This study demonstrates the effectiveness of diode laser energy for prostatic tissue coagulation and eventual sloughing. The results also demonstrate the safety of diode laser energy, with similar tissue response as seen with Nd:YAG laser, for laser prostatectomy.

  10. A 65-kV insulated gate bipolar transistor switch applied in damped AC voltages partial discharge detection system.

    Science.gov (United States)

    Jiang, J; Ma, G M; Luo, D P; Li, C R; Li, Q M; Wang, W

    2014-02-01

    Damped AC voltages detection system (DAC) is a productive way to detect the faults in power cables. To solve the problems of large volume, complicated structure and electromagnetic interference in existing switches, this paper developed a compact solid state switch based on electromagnetic trigger, which is suitable for DAC test system. Synchronous electromagnetic trigger of 32 Insulated Gate Bipolar Transistors (IGBTs) in series was realized by the topological structure of single line based on pulse width modulation control technology. In this way, external extension was easily achieved. Electromagnetic trigger and resistor-capacitor-diode snubber circuit were optimized to reduce the switch turn-on time and circular layout. Epoxy encapsulating was chosen to enhance the level of partial discharge initial voltage (PDIV). The combination of synchronous trigger and power supply is proposed to reduce the switch volume. Moreover, we have overcome the drawback of the electromagnetic interference and improved the detection sensitivity of DAC by using capacitor storage energy to maintain IGBT gate driving voltage. The experimental results demonstrated that the solid-state switch, with compact size, whose turn-on time was less than 400 ns and PDIV was more than 65 kV, was able to meet the actual demands of 35 kV DAC test system.

  11. Laser-triggered vacuum switch

    Science.gov (United States)

    Brannon, Paul J.; Cowgill, Donald F.

    1990-01-01

    A laser-triggered vacuum switch has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable.

  12. Efficient organic light emitting-diodes (OLEDs)

    CERN Document Server

    Chang, Yi-Lu

    2015-01-01

    Following two decades of intense research globally, the organic light-emitting diode (OLED) has steadily emerged as the ultimate display technology of choice for the coming decades. Portable active matrix OLED displays have already become prevalent, and even large-sized ultra-high definition 4K TVs are being mass-produced. More exotic applications such as wearable displays have been commercialized recently. With the burgeoning success in displays, researchers are actively bringing the technology forward into the exciting solid-state lighting market. This book presents the knowledge needed for

  13. Multifractal properties of resistor diode percolation.

    Science.gov (United States)

    Stenull, Olaf; Janssen, Hans-Karl

    2002-03-01

    Focusing on multifractal properties we investigate electric transport on random resistor diode networks at the phase transition between the nonpercolating and the directed percolating phase. Building on first principles such as symmetries and relevance we derive a field theoretic Hamiltonian. Based on this Hamiltonian we determine the multifractal moments of the current distribution that are governed by a family of critical exponents [psi(l)]. We calculate the family [psi(l)] to two-loop order in a diagrammatic perturbation calculation augmented by renormalization group methods.

  14. Particle diode: Rectification of interacting Brownian ratchets

    OpenAIRE

    Ai, Bao-quan; He, Ya-feng; Zhong, Wei-rong

    2012-01-01

    Transport of Brownian particles interacting with each other via the Morse potential is investigated in the presence of an ac driving force applied locally at one end of the chain. By using numerical simulations, we find that the system can behave as a particle diode for both overdamped and underdamped cases. For low frequencies, the transport from the free end to the ac acting end is prohibited, while the transport from the ac acting end to the free end is permitted. However, the polarity of ...

  15. Resonant tunneling diode oscillators for optical communications

    Science.gov (United States)

    Watson, Scott; Zhang, Weikang; Wang, Jue; Al-Khalidi, Abdullah; Cantu, Horacio; Figueiredo, Jose; Wasige, Edward; Kelly, Anthony E.

    2017-08-01

    The ability to use resonant tunneling diodes (RTDs) as both transmitters and receivers is an emerging topic, especially with regards to wireless communications. Successful data transmission has been achieved using electronic RTDs with carrier frequencies exceeding 0.3 THz. Specific optical-based RTDs, which act as photodetectors, have been developed by adjusting the device structure to include a light absorption layer and small optical windows on top of the device to allow direct optical access. This also allows the optical signal to directly modulate the RTD oscillation. Both types of RTD oscillators will allow for seamless integration of high frequency radio and optical fiber networks.

  16. Method for partially coating laser diode facets

    Science.gov (United States)

    Dholakia, Anil R. (Inventor)

    1990-01-01

    Bars of integral laser diode devices cleaved from a wafer are placed with their p regions abutting and n regions abutting. A thin BeCu mask having alternate openings and strips of the same width as the end facets is used to mask the n region interfaces so that multiple bars can be partially coated over their exposed p regions with a reflective or partial reflective coating. The partial coating permits identification of the emitting facet from the fully coated back facet during a later device mounting procedure.

  17. Wheat Under LED's (Light Emitting Diodes)

    Science.gov (United States)

    2004-01-01

    Astroculture is a suite of technologies used to produce and maintain a closed controlled environment for plant growth. The two most recent missions supported growth of potato, dwarf wheat, and mustard plants, and provided scientists with the first opportunity to conduct true plant research in space. Light emitting diodes have particular usefulness for plant growth lighting because they emit a much smaller amount of radiant heat than do conventional lighting sources and because they have potential of directing a higher percentage of the emitted light onto plants surfaces. Furthermore, the high output LED's have emissions in the 600-700 nm waveband, which is of highest efficiency for photosynthesis by plants.

  18. Constructing Diodes and Transistors for Ultracold Atoms

    Science.gov (United States)

    Pepino, Ronald; Cooper, John; Anderson, Dana; Holland, Murray

    2008-05-01

    The ultracold atom-optical analogy to electronic systems is presented, along with the master equation formalism that is applied to this novel physical context of system-reservoir interactions. The proposed formalism lends itself quite readily to not only the study of atomtronic systems, but also transport properties of ultracold atoms in optical lattices. We demonstrate how these systems can be configured so that they emulate the behavior of the electronic diode, field effect transistor (FET), and bipolar junction transistor (BJT). The behavior of simple logic gates: namely, the AND and OR gates are follow as direct consequences of the atomtronic BJTs.

  19. Laser materials processing with diode lasers

    OpenAIRE

    Li, Lin; Lawrence, Jonathan; Spencer, Julian T.

    1996-01-01

    Laser materials processing is currently dominated by CO2, Nd-YAG and Excimer lasers. Continuous advances in semiconductor laser technology over the last decade have increased the average power output of the devices annualy by two fold, resulting in the commercial availability of the diode lasers today with delivery output powers in excess of 60W in CW mode and 5kW in qasi-CW mode. The advantages of compactness, high reliability, high efficiency and potential low cost, due to the mass producti...

  20. Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

    Science.gov (United States)

    Bai, Yingxin; Yu, Jirong; Petzar, Paul; Petros, M.; Chen, Songsheng; Trieu, Bo; Lee, Nyung; Singh, U.

    2009-01-01

    Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

  1. MEMS switches having non-metallic crossbeams

    Science.gov (United States)

    Scardelletti, Maximillian C (Inventor)

    2009-01-01

    A RF MEMS switch comprising a crossbeam of SiC, supported by at least one leg above a substrate and above a plurality of transmission lines forming a CPW. Bias is provided by at least one layer of metal disposed on a top surface of the SiC crossbeam, such as a layer of chromium followed by a layer of gold, and extending beyond the switch to a biasing pad on the substrate. The switch utilizes stress and conductivity-controlled non-metallic thin cantilevers or bridges, thereby improving the RF characteristics and operational reliability of the switch. The switch can be fabricated with conventional silicon integrated circuit (IC) processing techniques. The design of the switch is very versatile and can be implemented in many transmission line mediums.

  2. On formalism and stability of switched systems

    DEFF Research Database (Denmark)

    Leth, John-Josef; Wisniewski, Rafal

    2012-01-01

    In this paper, we formulate a uniform mathematical framework for studying switched systems with piecewise linear partitioned state space and state dependent switching. Based on known results from the theory of differential inclusions, we devise a Lyapunov stability theorem suitable for this class...... of switched systems. With this, we prove a Lyapunov stability theorem for piecewise linear switched systems by means of a concrete class of Lyapunov functions. Contrary to existing results on the subject, the stability theorems in this paper include Filippov (or relaxed) solutions and allow infinite switching...... in finite time. Finally, we show that for a class of piecewise linear switched systems, the inertia of the system is not sufficient to determine its stability. A number of examples are provided to illustrate the concepts discussed in this paper....

  3. Switching control of an R/C hovercraft: stabilization and smooth switching.

    Science.gov (United States)

    Tanaka, K; Iwasaki, M; Wang, H O

    2001-01-01

    This paper presents stable switching control of an radio-controlled (R/C) hovercraft that is a nonholonomic (nonlinear) system. To exactly represent its nonlinear dynamics, more importantly, to maintain controllability of the system, we newly propose a switching fuzzy model that has locally Takagi-Sugeno (T-S) fuzzy models and switches them according to states, external variables, and/or time. A switching fuzzy controller is constructed by mirroring the rule structure of the switching fuzzy model of an R/C hovercraft. We derive linear matrix inequality (LMI) conditions for ensuring the stability of the closed-loop system consisting of a switching fuzzy model and controller. Furthermore, to guarantee smooth switching of control input at switching boundaries, we also derive a smooth switching condition represented in terms of LMIs. A stable switching fuzzy controller satisfying the smooth switching condition is designed by simultaneously solving both of the LMIs. The simulation and experimental results for the trajectory control of an R/C hovercraft show the validity of the switching fuzzy model and controller design, particularly, the smooth switching condition.

  4. Spectral control of diode lasers using external waveguide circuits

    NARCIS (Netherlands)

    Oldenbeuving, Ruud

    2013-01-01

    We investigated spectral control of diode lasers using external waveguide circuits. The purpose of this work is to investigate such external control for providing a new class of diode lasers with technologically interesting properties, such as a narrow spectral bandwidth and spectrally tunable

  5. Use of tunnel diode for nanosecond pulse amplification

    International Nuclear Information System (INIS)

    Chartier, P.

    1970-01-01

    In a first part, after a brief review of tunnel diode properties, the paper presents graphic and analytic investigations of series, shunt and compound connected tunnel diode amplifiers. A study of the noise problem is given. In a second part, practical realizations are described and results of measurements of their gain and noise characteristics are presented. (author) [fr

  6. Operation of AC Adapters Visualized Using Light-Emitting Diodes

    Science.gov (United States)

    Regester, Jeffrey

    2016-01-01

    A bridge rectifier is a diamond-shaped configuration of diodes that serves to convert alternating current(AC) into direct current (DC). In our world of AC outlets and DC electronics, they are ubiquitous. Of course, most bridge rectifiers are built with regular diodes, not the light-emitting variety, because LEDs have a number of disadvantages. For…

  7. Compact green-diode-based lasers for biophotonic bioimaging

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Hansen, Anders Kragh; Petersen, Paul Michael

    2014-01-01

    Diode lasers simultaneously offer tunability, high-power emission, and compact size at fairly low cost and are increasingly preferred for pumping titanium:sapphire lasers.......Diode lasers simultaneously offer tunability, high-power emission, and compact size at fairly low cost and are increasingly preferred for pumping titanium:sapphire lasers....

  8. Suitability of integrated protection diodes from diverse semiconductor technologies

    NARCIS (Netherlands)

    Wanum, M. van; Lebouille, T.T.N.; Visser, G.C.; Vliet, F.E. van

    2009-01-01

    In this article diodes from three different semiconductor technologies are compared based on their suitability to protect a receiver. The semiconductor materials involved are Silicon, Gallium Arsenide and Gallium Nitride. The diodes in the diverse semiconductor technologies themselves are close in

  9. AN ANALYTICAL STUDY OF SWITCHING TRACTION MOTORS

    Directory of Open Access Journals (Sweden)

    V. M. Bezruchenko

    2010-03-01

    Full Text Available The analytical study of switching of the tractive engines of electric locomotives is conducted. It is found that the obtained curves of change of current of the sections commuted correspond to the theory of average rectilinear switching. By means of the proposed method it is possible on the stage of design of tractive engines to forecast the quality of switching and to correct it timely.

  10. Switching X-Ray Tubes Remotely

    Science.gov (United States)

    Bulthuis, Ronald V.

    1990-01-01

    Convenient switch and relay circuit reduces risk of accidents. Proposed switching circuit for x-ray inspection system enables operator to change electrical connections to x-ray tubes remotely. Operator simply flips switch on conveniently-located selector box to change x-ray heads. Indicator lights on selector box show whether 160 or 320-kV head connected. Relays in changeover box provides proper voltages and coolants. Chance of making wrong connections and damaging equipment eliminated.

  11. Switched reluctance drives for electric vehicle applications

    OpenAIRE

    Andrada Gascón, Pedro; Torrent Burgués, Marcel; Blanqué Molina, Balduino; Perat Benavides, Josep Ignasi

    2003-01-01

    Electric vehicles are the only alternative for a clean, efficient and environmentally friendly urban transport system. With the increasing interest in electric drives for electric vehicle propulsion. This paper first tries to explain why the switched reluctance drive is a strong candidate for electric vehicle applications. It then gives switched reluctance drive design guidelines for battery or fuel cell operated electric vehicles. Finally, it presents the design and simulation of a switched ...

  12. Optical Multidimensional Switching for Data Center Networks

    DEFF Research Database (Denmark)

    Kamchevska, Valerija

    2017-01-01

    , the limitations of previously proposed optical subwavelength switching technologies are discussed and a novel concept of optical time division multiplexed switching is proposed. A detailed elaboration of the envisioned scheme is given, with a special focus on the problem of synchronization. A novel...... synchronization algorithm for the Hi-Ring architecture is proposed and experimentally validated. Furthermore, software controlled switching in the data plane is experimentally demonstrated when the proposed algorithm is used for synchronization. Finally, integration is discussed from two different perspectives...

  13. Monitoring Mellanox Infiniband SX6036 switches

    CERN Document Server

    Agapiou, Marinos

    2017-01-01

    The SX6036 switches addressed by my project, are part of a fully non-blocking fat-tree cluster consisting of 72 servers and 6 Mellanox SX6036 Infiniband switches. My project is about retrieving the appropriate metrics from the Infiniband switch cluster, ingesting the data to Collectd and after my data are being transfered to CERN Database, they are being visualized via Grafana Dashboards.

  14. Atomic crystals resistive switching memory

    International Nuclear Information System (INIS)

    Liu Chunsen; Zhang David Wei; Zhou Peng

    2017-01-01

    Facing the growing data storage and computing demands, a high accessing speed memory with low power and non-volatile character is urgently needed. Resistive access random memory with 4F 2 cell size, switching in sub-nanosecond, cycling endurances of over 10 12 cycles, and information retention exceeding 10 years, is considered as promising next-generation non-volatile memory. However, the energy per bit is still too high to compete against static random access memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder the further scaling down. The variation of resistance between different devices and even various cycles in the same device, hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fine interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreover, the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory. (topical reviews)

  15. Atomic battery with beam switching

    International Nuclear Information System (INIS)

    Edling, E.A.; McKenna, R.P.; Peterick, E.Th. Jr.; Trexler, F.D.

    1984-01-01

    An electric power generating apparatus that is powered primarily by the emission of electrically charged particles from radio-active materials enclosed in an evacuated vessel of glass or the like. An arrangement of reflecting electrodes causes a beam of particles to switch back and forth at a high frequency between two collecting electrodes that are connected to a resonating tuned primary circuit consisting of an inductor with resonating capacitor. The reflecting electrodes are energized in the proper phase relationship to the collecting electrodes to insure sustained oscillation by means of a secondary winding coupled inductively to the primary winding and connected to the reflecting electrodes. Power may be drawn from the circuit at a stepped down voltage from a power take-off winding that is coupled to the primary winding. The disclosure also describes a collecting electrode arrangement consisting of multiple spatially separated electrodes which together serve to capture a maximum of the available particle energy. A self-starting arrangement for start of oscillations is described. A specially adapted version of the invention utilizes two complementary beams of oppositely charged particles which are switched alternatingly between the collecting electrodes

  16. Diode-pumped efficient laser operation and spectroscopy of Tm,Ho:YVO 4

    Science.gov (United States)

    Li, G.; Yao, B. Q.; Meng, P. B.; Duan, X. M.; Ju, Y. L.; Wang, Y. Z.

    2011-04-01

    Spectroscopic characterization of co-doped Tm,Ho:YVO 4 crystal grown by the Czochralski method has been performed including absorption spectrum, emitting spectrum and luminescence decay lifetime. The polarization emitting spectrum around 2 μm is accomplished by exciting a singly Ho 3+ doped YVO 4 crystal to exclude the influence of Tm 3+3F 4- 3H 6 transition and the emission cross section is deduced from both Fuchtbauer-Ladenburg (F-L) equation and reciprocity method (RM). In addition, we report up to 10.4 W continuous wave (CW) output with a conversion efficiency of 40% and 10.3 W Q-Switch output with 12.5 kHz pulse repetition rate of diode-pumped cryogenic Tm,Ho:YVO 4 laser. For Q-Switch operation, the minimum pulse width of 28.2 ns is obtained, all of which demonstrate that the Tm,Ho:YVO 4 is excellent laser material for 2 μm radiation.

  17. Multiple night-time light-emitting diode lighting strategies impact grassland invertebrate assemblages.

    Science.gov (United States)

    Davies, Thomas W; Bennie, Jonathan; Cruse, Dave; Blumgart, Dan; Inger, Richard; Gaston, Kevin J

    2017-07-01

    White light-emitting diodes (LEDs) are rapidly replacing conventional outdoor lighting technologies around the world. Despite rising concerns over their impact on the environment and human health, the flexibility of LEDs has been advocated as a means of mitigating the ecological impacts of globally widespread outdoor night-time lighting through spectral manipulation, dimming and switching lights off during periods of low demand. We conducted a three-year field experiment in which each of these lighting strategies was simulated in a previously artificial light naïve grassland ecosystem. White LEDs both increased the total abundance and changed the assemblage composition of adult spiders and beetles. Dimming LEDs by 50% or manipulating their spectra to reduce ecologically damaging wavelengths partially reduced the number of commoner species affected from seven to four. A combination of dimming by 50% and switching lights off between midnight and 04:00 am showed the most promise for reducing the ecological costs of LEDs, but the abundances of two otherwise common species were still affected. The environmental consequences of using alternative lighting technologies are increasingly well established. These results suggest that while management strategies using LEDs can be an effective means of reducing the number of taxa affected, averting the ecological impacts of night-time lighting may ultimately require avoiding its use altogether. © 2017 John Wiley & Sons Ltd.

  18. Water Vapour Propulsion Powered by a High-Power Laser-Diode

    Science.gov (United States)

    Minami, Y.; Uchida, S.

    Most of the laser propulsion schemes now being proposed and developed assume neither power supplies nor on-board laser devices and therefore are bound to remote laser stations like a kite via a laser beam “string”. This is a fatal disadvantage for a space vehicle that flies freely though it is often said that no need of installing an energy source is an advantage of a laser propulsion scheme. The possibility of an independent laser propulsion space vehicle that carries a laser source and a power supply on board is discussed. This is mainly due to the latest development of high power laser diode (LD) technology. Both high specific impulse-low thrust mode and high thrust-low specific impulse mode can be selected by controlling the laser output by using vapour or water as a propellant. This mode change can be performed by switching between a high power continuous wave (cw), LD engine for high thrust with a low specific impulse mode and high power LD pumping Q-switched Nd:YAG laser engine for low thrust with the high specific impulse mode. This paper describes an Orbital Transfer Vehicle equipped with the above-mentioned laser engine system and fuel cell that flies to the Moon from a space platform or space hotel in Earth orbit, with cargo shipment from lunar orbit to the surface of the Moon, including the possibility of a sightseeing trip.

  19. Stochastic multistep polarization switching in ferroelectrics

    Science.gov (United States)

    Genenko, Y. A.; Khachaturyan, R.; Schultheiß, J.; Ossipov, A.; Daniels, J. E.; Koruza, J.

    2018-04-01

    Consecutive stochastic 90° polarization switching events, clearly resolved in recent experiments, are described by a nucleation and growth multistep model. It extends the classical Kolmogorov-Avrami-Ishibashi approach and includes possible consecutive 90°- and parallel 180° switching events. The model predicts the results of simultaneous time-resolved macroscopic measurements of polarization and strain, performed on a tetragonal Pb (Zr ,Ti ) O3 ceramic in a wide range of electric fields over a time domain of seven orders of magnitude. It allows the determination of the fractions of individual switching processes, their characteristic switching times, activation fields, and respective Avrami indices.

  20. The increased importance of sector switching

    DEFF Research Database (Denmark)

    Frederiksen, Anders; Hansen, Jesper Rosenberg

    2017-01-01

    Sector switching is an important phenomenon that casts light on public–private differences. Yet our knowledge about its prevalence and trends is limited. We study sector switching using unique Danish register-based employer–employee data covering more than 25 years. We find that sector switching...... constitutes 18.5% of all job-to-job mobility, and the trend is increasing both from public to private and from private to public. Sector switching is also generally increasing for middle managers, but for administrative professionals only the flows from private to public increase and for top managers only...

  1. Low-Voltage Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Bidari, E.; Keskin, M.; Maloberti, F.

    1999-01-01

    Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications.......Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications....

  2. Mechanism of single atom switch on silicon

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Thirstrup, C.

    1998-01-01

    We demonstrate single atom switch on silicon which operates by displacement of a hydrogen atom on the silicon (100) surface at room temperature. We find two principal effects by which the switch is controlled: a pronounced maximum of the switching probability as function of sample bias...... and a preferred direction of switching as function of STM tip position. Based on first principles calculations, are show that this behaviour is due to a novel mechanism involving an electronic excitation of a localized surface resonance. (C) 1998 Elsevier Science B.V. All rights reserved....

  3. Clocking Scheme for Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1998-01-01

    A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed.......A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed....

  4. Diode-Assisted Buck-Boost Voltage-Source Inverters

    DEFF Research Database (Denmark)

    Gao, Feng; Loh, Poh Chiang; Teodorescu, Remus

    2009-01-01

    , a number of diode-assisted inverter variants can be designed with each having its own operational principle and voltage gain expression. For controlling them, a generic modulation scheme that can be used for controlling all diode-assisted variants with minimized harmonic distortion and component stress......This paper proposes a number of diode-assisted buck-boost voltage-source inverters with a unique X-shaped diode-capacitor network inserted between the inverter circuitry and dc source for producing a voltage gain that is comparatively higher than those of other buck-boost conversion techniques....... Using the diode-assisted network, the proposed inverters can naturally configure themselves to perform capacitive charging in parallel and discharging in series to give a higher voltage multiplication factor without compromising waveform quality. In addition, by adopting different front-end circuitries...

  5. Linear diode laser bar optical stretchers for cell deformation

    Science.gov (United States)

    Sraj, Ihab; Marr, David W.M.; Eggleton, Charles D.

    2010-01-01

    To investigate the use of linear diode laser bars to optically stretch cells and measure their mechanical properties, we present numerical simulations using the immersed boundary method (IBM) coupled with classic ray optics. Cells are considered as three-dimensional (3D) spherical elastic capsules immersed in a fluid subjected to both optical and hydrodynamic forces in a periodic domain. We simulate cell deformation induced by both single and dual diode laser bar configurations and show that a single diode laser bar induces significant stretching but also induces cell translation of speed < 10 µm/sec for applied 6.6 mW/µm power in unconfined systems. The dual diode laser bar configuration, however, can be used to both stretch and optically trap cells at a fixed position. The net cell deformation was found to be a function of the total laser power and not the power distribution between single or dual diode laser bar configurations. PMID:21258483

  6. Processes governing pinch formation in diodes

    International Nuclear Information System (INIS)

    Blaugrund, A.E.; Cooperstein, G.; Goldstein, S.A.

    1975-01-01

    The process of pinch formation in large aspect ratio diodes has been studied by means of streak photography and time-resolved x-ray detectors. A tight pinch is formed at the anode center by a collapsing thin hollow electron beam. The collapse velocity depends, among other things, on the type of material in the top 1 μm layer of the anode. In a tentative model it is assumed that an anode plasma is at least partially created from gases released from the surface layer of the anode by the heating action of the beam. These gases are ionized by primary, backscattered, and secondary electrons. Ions emitted from this plasma modify the electron trajectories in the diode leading to a radial collapse of the hollow electron beam. The observed monotonic dependence of the collapse velocity on the atomic number of the anode material can be explained by the smooth dependence on Z of both the specific heat and the electron backscatter coefficient. In the case of high-Z anodes the ion expansion time appears to be the factor limiting the collapse velocity. Detailed experimental data are presented

  7. The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiquan [Stanford Univ., CA (United States)

    2008-12-01

    In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

  8. Design and implementation of a bidirectional current-controlled voltage-regulated DC-DC switched-mode converter

    CSIR Research Space (South Africa)

    Coetzer, A

    2016-01-01

    Full Text Available . That is to say, 2 A. 2.1 Soft Start Circuit The two-stage soft-start circuit comprises pre- and post-charge mechanisms [1]. The pre-charge circuit limits the peak battery in-rush current to 5 A by means of four parallel connected 100 Ω resistors. At such time... as the bus capacitor C is charged to the battery potential (through the anti-parallel diode of switch Q1) the resistors are short-circuited by a relay (effectively removing the resistors from circuit). A resistor divider (connected across the DC bus), a...

  9. Comparison of Power Supply Pumping of Switch-Mode Audio Power Amplifiers with Resistive Loads and Loudspeakers as Loads

    DEFF Research Database (Denmark)

    Knott, Arnold; Petersen, Lars Press

    2013-01-01

    Power supply pumping is generated by switch-mode audio power amplifiers in half-bridge configuration, when they are driving energy back into their source. This leads in most designs to a rising rail voltage and can be destructive for either the decoupling capacitors, the rectifier diodes...... in the power supply or the power stage of the amplifier. Therefore precautions are taken by the amplifier and power supply designer to avoid those effects. Existing power supply pumping models are based on an ohmic load attached to the amplifier. This paper shows the analytical derivation of the resulting...

  10. 49 CFR 236.6 - Hand-operated switch equipped with switch circuit controller.

    Science.gov (United States)

    2010-10-01

    ... controller. 236.6 Section 236.6 Transportation Other Regulations Relating to Transportation (Continued... switch circuit controller. Hand-operated switch equipped with switch circuit controller connected to the point, or with facing-point lock and circuit controller, shall be so maintained that when point is open...

  11. Active and fast charge-state switching of single NV centres in diamond by in-plane Al-Schottky junctions

    Directory of Open Access Journals (Sweden)

    Christoph Schreyvogel

    2016-11-01

    Full Text Available In this paper, we demonstrate an active and fast control of the charge state and hence of the optical and electronic properties of single and near-surface nitrogen-vacancy centres (NV centres in diamond. This active manipulation is achieved by using a two-dimensional Schottky-diode structure from diamond, i.e., by using aluminium as Schottky contact on a hydrogen terminated diamond surface. By changing the applied potential on the Schottky contact, we are able to actively switch single NV centres between all three charge states NV+, NV0 and NV− on a timescale of 10 to 100 ns, corresponding to a switching frequency of 10–100 MHz. This switching frequency is much higher than the hyperfine interaction frequency between an electron spin (of NV− and a nuclear spin (of 15N or 13C for example of 2.66 kHz. This high-frequency charge state switching with a planar diode structure would open the door for many quantum optical applications such as a quantum computer with single NVs for quantum information processing as well as single 13C atoms for long-lifetime storage of quantum information. Furthermore, a control of spectral emission properties of single NVs as a single photon emitters – embedded in photonic structures for example – can be realized which would be vital for quantum communication and cryptography.

  12. Demonstration of Synaptic Behaviors and Resistive Switching Characterizations by Proton Exchange Reactions in Silicon Oxide

    Science.gov (United States)

    Chang, Yao-Feng; Fowler, Burt; Chen, Ying-Chen; Zhou, Fei; Pan, Chih-Hung; Chang, Ting-Chang; Lee, Jack C.

    2016-02-01

    We realize a device with biological synaptic behaviors by integrating silicon oxide (SiOx) resistive switching memory with Si diodes. Minimal synaptic power consumption due to sneak-path current is achieved and the capability for spike-induced synaptic behaviors is demonstrated, representing critical milestones for the use of SiO2-based materials in future neuromorphic computing applications. Biological synaptic behaviors such as long-term potentiation (LTP), long-term depression (LTD) and spike-timing dependent plasticity (STDP) are demonstrated systematically using a comprehensive analysis of spike-induced waveforms, and represent interesting potential applications for SiOx-based resistive switching materials. The resistive switching SET transition is modeled as hydrogen (proton) release from (SiH)2 to generate the hydrogen bridge defect, and the RESET transition is modeled as an electrochemical reaction (proton capture) that re-forms (SiH)2. The experimental results suggest a simple, robust approach to realize programmable neuromorphic chips compatible with large-scale CMOS manufacturing technology.

  13. 3-5 modulation and switching devices for optical systems applications

    Science.gov (United States)

    Singh, Jasprit; Bhattacharya, Pallab

    1995-04-01

    The thrust for this three year program has been to develop novel devices and systems applications for multiple quantum well based devices. We have investigated architectures based upon the quantum confined Stark effect (QCSE), a means by which excitonic resonances in a quantum well are electric field tuned to shift the peaked absorption spectrum of the material. The devices based upon this concept have been used, in the past, to realize switching structures employing the characteristic negative differential resistance available in PIN-MQW diodes under illumination. We have focuses, primarily on three schemes based upon the QCSE, to extend the utility of quantum well based devices. Firstly, we have developed, tested and optimized a novel tunable optical filter for wavelength selective applications. Secondly, we have demonstrated an MQW based scheme for optical pattern recognition which we have applied towards header recognition in a packet switching network environment. Thirdly, we have extended previous MQW based switching schemes to implement an optical read only memory (ROM) which can store two bits of information on a single sight, read by two different probe wavelengths of light.

  14. Superconducting switch and amplifier device

    International Nuclear Information System (INIS)

    Faris, S.M.

    1982-01-01

    An amplifying or switching superconductive device is described whose current-voltage characteristic is drastically altered by heavy injection of excess energetic quasi-particles. In this device, the superconducting bandgap of a superconducting layer is greatly altered by overinjection of energetic quasi-particles so that the bandgap changes greatly with respect to its thermal equilibrium value, and in most cases is made to vanish. In a preferred embodiment, a three electrode device is fabricated where at least one of the electrodes is a superconductor. Tunnel barriers are located between the electrodes. A first tunnel junction is used to heavily inject energetic quasi-particles into the superconducting electrode to change its superconducting bandgap drastically. In turn, this greatly modifies the currentvoltage characteristics of the second tunnel junction. This device can be used to provide logic circuits, or as an amplifier, and has an output sufficiently large that it can drive other similar devices

  15. Unity power factor switching regulator

    Science.gov (United States)

    Rippel, Wally E. (Inventor)

    1983-01-01

    A single or multiphase boost chopper regulator operating with unity power factor, for use such as to charge a battery is comprised of a power section for converting single or multiphase line energy into recharge energy including a rectifier (10), one inductor (L.sub.1) and one chopper (Q.sub.1) for each chopper phase for presenting a load (battery) with a current output, and duty cycle control means (16) for each chopper to control the average inductor current over each period of the chopper, and a sensing and control section including means (20) for sensing at least one load parameter, means (22) for producing a current command signal as a function of said parameter, means (26) for producing a feedback signal as a function of said current command signal and the average rectifier voltage output over each period of the chopper, means (28) for sensing current through said inductor, means (18) for comparing said feedback signal with said sensed current to produce, in response to a difference, a control signal applied to the duty cycle control means, whereby the average inductor current is proportionate to the average rectifier voltage output over each period of the chopper, and instantaneous line current is thereby maintained proportionate to the instantaneous line voltage, thus achieving a unity power factor. The boost chopper is comprised of a plurality of converters connected in parallel and operated in staggered phase. For optimal harmonic suppression, the duty cycles of the switching converters are evenly spaced, and by negative coupling between pairs 180.degree. out-of-phase, peak currents through the switches can be reduced while reducing the inductor size and mass.

  16. Low-Voltage Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Bidari, E.; Keskin, M.; Maloberti, F.

    1999-01-01

    Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications....

  17. Tutorial: Integrated-photonic switching structures

    Science.gov (United States)

    Soref, Richard

    2018-02-01

    Recent developments in waveguided 2 × 2 and N × M photonic switches are reviewed, including both broadband and narrowband resonant devices for the Si, InP, and AlN platforms. Practical actuation of switches by electro-optical and thermo-optical techniques is discussed. Present datacom-and-computing applications are reviewed, and potential applications are proposed for chip-scale photonic and optoelectronic integrated switching networks. Potential is found in the reconfigurable, programmable "mesh" switches that enable a promising group of applications in new areas beyond those in data centers and cloud servers. Many important matrix switches use gated semiconductor optical amplifiers. The family of broadband, directional-coupler 2 × 2 switches featuring two or three side-coupled waveguides deserves future experimentation, including devices that employ phase-change materials. The newer 2 × 2 resonant switches include standing-wave resonators, different from the micro-ring traveling-wave resonators. The resonant devices comprise nanobeam interferometers, complex-Bragg interferometers, and asymmetric contra-directional couplers. Although the fast, resonant devices offer ultralow switching energy, ˜1 fJ/bit, they have limitations. They require several trade-offs when deployed, but they do have practical application.

  18. Novel RF-MEMS capacitive switching structures

    NARCIS (Netherlands)

    Rottenberg, X.; Jansen, Henricus V.; Fiorini, P.; De Raedt, W.; Tilmans, H.A.C.

    2002-01-01

    This paper reports on novel RF-MEMS capacitive switching devices implementing an electrically floating metal layer covering the dielectric to ensure intimate contact with the bridge in the down state. This results in an optimal switch down capacitance and allows optimisation of the down/up

  19. Internal Backpressure for Terabit Switch Fabrics

    DEFF Research Database (Denmark)

    Fagertun, Anna Manolova; Ruepp, Sarah Renée; Rytlig, Andreas

    2012-01-01

    This paper proposes and analyzes the efficiency of novel backpressure schemes for Terabit switch fabrics. The proposed schemes aim at buffer optimization under uniform traffic distribution with Bernoulli packet arrival process. Results show that a reduction of the needed maximum buffer capacity w...... with up to 47% can be achieved with switch-internal backpressure mechanisms at the expense of a small control overhead....

  20. Ice-release coating for disconnect switches

    Science.gov (United States)

    Mundon, J. L.

    1980-03-01

    Several coatings for ice release, heat dissipation, thermal cycling, and outdoor weathering properties were evaluated. The coating having the most desired performance were applied to full scale switch components. The full scale switches were tested for ice performance and heat dissipation and the results were compared with those on identical switches with uncoated components. The coating chosen for application to switch components was installed on several switches for field evaluation during the winter of 1979 and 1980. It was offered for commercial application for installation to existing switch installations. Results indicate that the coating also exhibits excellent heat dissipation properties and may be used to improve heat dissipation of switch blades and other components. The coating material is unaffected by sunlight; it is a two component, Teflon-filled polyurethane that is available from two sources. The material is currently used for a variety of purposes, such as: aircraft wing and leading edge areas, hydrofoils, conveyor chutes and many others. Light gray in color, it is an excellent heat dissipator and matches the gray insulators used with most switches.

  1. Proceedings of the switched power workshop

    International Nuclear Information System (INIS)

    Fernow, R.C.

    1988-01-01

    These proceedings contain most of the presentations given at a workshop on the current state of research in techniques for switched power acceleration. The proceedings are divided, as was the workshop itself, into two parts. Part 1, contains the latest results from a number of groups active in switched power research. The major topic here is a method for switching externally supplied power onto a transmission line. Advocates for vacuum photodiode switching, solid state switching, gas switching, and synthetic pulse generation are all presented. Other important areas of research described in this section concern: external electrical and laser pulsing systems; the properties of the created electromagnetic pulse; structures used for transporting the electromagnetic pulse to the region where the electron beam is located; and possible applications. Part 2 of the proceedings considers the problem of designing a high brightness electron gun using switched power as the power source. This is an important first step in demonstrating the usefulness of switched power techniques for accelerator physics. In addition such a gun could have immediate practical importance for advanced acceleration studies since the brightness could exceed that of present sources by several orders of magnitude. I would like to take this opportunity to thank Kathleen Tuohy and Patricia Tuttle for their assistance in organizing and running the workshop. Their tireless efforts contribute greatly to a very productive meeting

  2. Photonic crystal Fano lasers and Fano switches

    DEFF Research Database (Denmark)

    Mørk, Jesper; Yu, Yi; Bekele, Dagmawi Alemayehu

    2017-01-01

    We show that Fano resonances can be realized in photonic crystal membrane structures by coupling line-defect waveguides and point-defect nanocavities. The Fano resonance can be exploited to realize optical switches with very small switching energy, as well as Fano lasers, that can generate short...

  3. High-explosive driven crowbar switch

    International Nuclear Information System (INIS)

    Dike, R.S.; Kewish, R.W. Jr.

    1976-01-01

    The disclosure relates to a compact explosive driven switch for use as a low resistance, low inductance crowbar switch. A high-explosive charge extrudes a deformable conductive metallic plate through a polyethylene insulating layer to achieve a hard current contact with a supportive annular conductor

  4. Simulation of linear Switched Reluctance Motor drives

    OpenAIRE

    Garcia Amoros, Jordi; Blanqué Molina, Balduino; Andrada Gascón, Pedro

    2011-01-01

    This paper presents a simulation model of linear switched reluctance motor drives. A Matlab-Simulink environment coupled with finite element analysis is used to perform the simulations. Experimental and simulation results for a double sided linear switched motor drive prototype are reported and compared to verify the simulation model.

  5. Development of High Power X-Band Semiconductor RF Switch for Pulse Compression Systems of Future Linear Colliders

    International Nuclear Information System (INIS)

    Tantawi, Sami

    2000-01-01

    We describe development of semiconductor X-band high-power RF switches. The target applications are high-power RF pulse compression systems for future linear colliders. We describe the design methodology of the architecture of the whole switch systems. We present the scaling law that governs the relation between power handling capability and number of elements. We designed and built several active waveguide windows for the active element. The waveguide window is a silicon wafer with an array of four hundred PIN/NIP diodes covering the surface of the window. This waveguide window is located in an over-moded TE01 circular waveguide. The results of high power RF measurements of the active waveguide window are presented. The experiment is performed at power levels of a few megawatts at X-band

  6. Nanosecond pulse generation in a passively Q-switched Nd:GGG laser at 1331 nm by CVD graphene saturable absorber

    Science.gov (United States)

    Xu, Bin; Wang, Yi; Cheng, Yongjie; Yang, Han; Xu, Huiying; Cai, Zhiping

    2015-10-01

    We report on a nanosecond pulse generation in a diode end-pumped passively Q-switched Nd:GGG laser at the low-gain transition line of 1331 nm. A three-layer CVD graphene thin film was transferred from Cu foil to a BK7 glass substrate for the use of saturable absorber. A stable Q-switching laser operation was obtained with maximum average output power of 0.69 W and slope efficiency of about 11.0% with respect to the absorbed pump power. The shortest pulse duration and the maximum repetition rate of the pulse trains were registered to be 556 ns and 166.7 kHz with corresponding maximum pulse energy 4.14 μJ and pulse peak power 7.45 W. This is the first demonstration of CVD-graphene-based Q-switched laser operation at 1.3 μm, to the best of our knowledge.

  7. Enhanced performance of acousto-optic Q-switched Er:Yb:RAl3(BO3)4 (R = Y and Lu) pulse lasers at 1580 nm

    International Nuclear Information System (INIS)

    Chen, Y J; Lin, Y F; Huang, J H; Gong, X H; Luo, Z D; Huang, Y D

    2013-01-01

    By using mirrors with specially designed transmissions in a diode end-pumped hemispherical cavity, laser oscillations except for 1580 nm were suppressed and an enhanced pulse performance of an acousto-optic Q-switched laser at a single wavelength of 1580 nm was realized for Er:Yb:RAl 3 (BO 3 ) 4 crystals. When the absorbed pump power was 13.5 W and the pulse repetition frequency was 1 kHz, 250 μJ Q-switched pulse energy with a width of 215 ns and 350 μJ Q-switched pulse energy with a width of 125 ns were achieved in Er:Yb:YAl 3 (BO 3 ) 4 and Er:Yb:LuAl 3 (BO 3 ) 4 crystals, respectively. The pulsed laser performances of both the crystals were also compared and investigated in detail. (paper)

  8. Light-Emitting Diodes: Phosphorescent Nanocluster Light-Emitting Diodes (Adv. Mater. 2/2016).

    Science.gov (United States)

    Kuttipillai, Padmanaban S; Zhao, Yimu; Traverse, Christopher J; Staples, Richard J; Levine, Benjamin G; Lunt, Richard R

    2016-01-13

    On page 320, R. R. Lunt and co-workers demonstrate electroluminescence from earth-abundant phosphorescent metal halide nanoclusters. These inorganic emitters, which exhibit rich photophysics combined with a high phosphorescence quantum yield, are employed in red and near-infrared light-emitting diodes, providing a new platform of phosphorescent emitters for low-cost and high-performance light-emission applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Seismic switch for strong motion measurement

    Science.gov (United States)

    Harben, P.E.; Rodgers, P.W.; Ewert, D.W.

    1995-05-30

    A seismic switching device is described that has an input signal from an existing microseismic station seismometer and a signal from a strong motion measuring instrument. The seismic switch monitors the signal level of the strong motion instrument and passes the seismometer signal to the station data telemetry and recording systems. When the strong motion instrument signal level exceeds a user set threshold level, the seismometer signal is switched out and the strong motion signal is passed to the telemetry system. The amount of time the strong motion signal is passed before switching back to the seismometer signal is user controlled between 1 and 15 seconds. If the threshold level is exceeded during a switch time period, the length of time is extended from that instant by one user set time period. 11 figs.

  10. A Mechanical Switch Using Spectral Microshifts

    Science.gov (United States)

    Mitchell, Gordon L.; Saaski, Elric W.; Hartl, James C.

    1989-02-01

    Among the simplest fiber optic sensors, are those which operate in a binary fashion; they were the first sensor types to be developed. Early experiments with fiber bundles and shutters produced demonstrations of, for example, displacement sensors. Typical applications range from position sensing for aircraft landing gear to counting objects on a production line. Because they frequently replace electrical snap action switches, binary sensors are generally called optical switches. Optical switch applications account for a much larger market than the more complex analog measurements discussed in the balance of this volume. This paper presents an optical switch concept that uses a single fiber and is tolerant of back reflections. The sensor element is a low finesse Fabry-Perot pressure sensor which replaces the electrical contact in a conventional snap action switch.

  11. A practical guide to handling laser diode beams

    CERN Document Server

    Sun, Haiyin

    2015-01-01

    This book offers the reader a practical guide to the control and characterization of laser diode beams.  Laser diodes are the most widely used lasers, accounting for 50% of the global laser market.  Correct handling of laser diode beams is the key to the successful use of laser diodes, and this requires an in-depth understanding of their unique properties. Following a short introduction to the working principles of laser diodes, the book describes the basics of laser diode beams and beam propagation, including Zemax modeling of a Gaussian beam propagating through a lens.  The core of the book is concerned with laser diode beam manipulations: collimating and focusing, circularization and astigmatism correction, coupling into a single mode optical fiber, diffractive optics and beam shaping, and manipulation of multi transverse mode beams.  The final chapter of the book covers beam characterization methods, describing the measurement of spatial and spectral properties, including wavelength and linewidth meas...

  12. Quaternary InGaAsSb Thermophotovoltaic Diodes

    Energy Technology Data Exchange (ETDEWEB)

    MW Dashiell; JF Beausang; H Ehsani; GJ Nichols; DM Depoy; LR Danielson; P Talamo; KD Rahner; EJ Brown; SR Burger; PM Foruspring; WF Topper; PF Baldasaro; CA Wang; R Huang; M Connors; G Turner; Z Shellenbarger; G Taylor; J Li; R Martinelli; D Donetski; S Anikeev; G Belenky; S Luryi

    2006-03-09

    In{sub x}Ga{sub 1-x}As{sub y}Sb{sub 1-y} thermophotovoltaic (TPV) diodes were grown lattice-matched to GaSb substrates by Metal Organic Vapor Phase Epitaxy (MOVPE) in the bandgap range of E{sub G} = 0.5 to 0.6eV. InGaAsSb TPV diodes, utilizing front-surface spectral control filters, are measured with thermal-to-electric conversion efficiency and power density of {eta}{sub TPV} = 19.7% and PD =0.58 W/cm{sup 2} respectively for a radiator temperature of T{sub radiator} = 950 C, diode temperature of T{sub diode} = 27 C, and diode bandgap of E{sub G} = 0.53eV. Practical limits to TPV energy conversion efficiency are established using measured recombination coefficients and optical properties of front surface spectral control filters, which for 0.53eV InGaAsSb TPV energy conversion is {eta}{sub TPV} = 28% and PD = 0.85W/cm{sup 2} at the above operating temperatures. The most severe performance limits are imposed by (1) diode open-circuit voltage (VOC) limits due to intrinsic Auger recombination and (2) parasitic photon absorption in the inactive regions of the module. Experimentally, the diode V{sub OC} is 15% below the practical limit imposed by intrinsic Auger recombination processes. Analysis of InGaAsSb diode electrical performance vs. diode architecture indicate that the V{sub OC} and thus efficiency is limited by extrinsic recombination processes such as through bulk defects.

  13. Design and evaluation of the XBT diode

    International Nuclear Information System (INIS)

    Wright, E.L.; Vlieks, A.; Fant, K.; Pearson, C.; Koontz, R.; Jensen, D.; Miram, G.

    1993-01-01

    This paper describes the design and experimental results achieved with the 440 kV, microperveance 1.9, XBT (X-band Beam Tester) diode. The Pierce gun was developed for the 100 MW X-band klystron; the high power RF source to be used on the NLC (Next Linear Collider). The gun is electrostatically focused (no magnetic compression) to a beam diameter of 6.35 mm, with an area convergence of 110:1. Maximum cathode loading is approximately 25 A/cm 2 , with a beam power density of 770 MW/cm 2 . The measured beam current was within 2% of the value predicted by simulation with EGUN. Transmission through the highly instrumented beam tester was 99.98%. Some novel techniques were used to achieve near perfect beam transmission, which include the use of a reentrant-floating input pole piece

  14. Kinetics of current formation in molecular diode

    International Nuclear Information System (INIS)

    Petrov, Eh.G.; Leonov, V.A.; Shevchenko, E.V.

    2012-01-01

    Based on the kinetic theory of election transfer in low-dimensional molecular systems, the formation of transient and stationary currents in a system 'electrode l-molecule-electrode 2' (molecular diode) is studied for different regimes of charge transmission. In the framework of the HOMO-LUMO molecular model, a situation is considered where the current formation is initiated either by molecule photoexcitation or by change of interelectrode voltage bias. It is found that the distant (tunnel) inelastic electron transfer plays a crucial role in changing molecular electronic states and, as a result, in generating transmission channels for hopping (sequential) and distant (direct) current components. The effect of inelastic tunneling is especially pronounced in the condition of resonant electron transmission.

  15. High Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal

    Semiconductor nanowires (NWs) have emerged as a promising technology for future electronic and optoelectronic devices. Epitaxial growth of III-V materials on Si substrates have been demonstrated, allowing for low-cost production. As the lattice matching requirements are much less strict than...... for planar growth, many new materials combinations can be grown in a single NW. This opens up exciting opportunities for NW-based high-performance solar cells, where previously inaccessible materials combinations can now be chosen to match the solar spectrum. A key component of a multi-junction solar cell...... NWs were contacted in a NW-FET setup. Electrical measurements at room temperature display typical tunnel diode behavior, with a Peak-to-Valley Current Ratio (PVCR) as high as 8.2 and a peak current density as high as 329 A/cm2. Low temperature measurements show improved PVCR of up to 27.6....

  16. Light-emitting diodes for analytical chemistry.

    Science.gov (United States)

    Macka, Mirek; Piasecki, Tomasz; Dasgupta, Purnendu K

    2014-01-01

    Light-emitting diodes (LEDs) are playing increasingly important roles in analytical chemistry, from the final analysis stage to photoreactors for analyte conversion to actual fabrication of and incorporation in microdevices for analytical use. The extremely fast turn-on/off rates of LEDs have made possible simple approaches to fluorescence lifetime measurement. Although they are increasingly being used as detectors, their wavelength selectivity as detectors has rarely been exploited. From their first proposed use for absorbance measurement in 1970, LEDs have been used in analytical chemistry in too many ways to make a comprehensive review possible. Hence, we critically review here the more recent literature on their use in optical detection and measurement systems. Cloudy as our crystal ball may be, we express our views on the future applications of LEDs in analytical chemistry: The horizon will certainly become wider as LEDs in the deep UV with sufficient intensity become available.

  17. AC and DC Impedance Extraction for 3-Phase and 9-Phase Diode Rectifiers Utilizing Improved Average Mathematical Models

    Directory of Open Access Journals (Sweden)

    Shahbaz Khan

    2018-03-01

    Full Text Available Switching models possess discontinuous and nonlinear behavior, rendering difficulties in simulations in terms of time consumption and computational complexity, leading to mathematical instability and an increase in its vulnerability to errors. This issue can be countered by averaging detailed models over the entire switching period. An attempt is made for deriving improved dynamic average models of three phase (six-pulse and nine phase (18-pulse diode rectifiers by approximating load current through first order Taylor series. Small signal AC/DC impedances transfer functions of the average models are obtained using a small signal current injection technique in Simulink, while transfer functions are obtained through identification of the frequency response into the second order system. For the switch models in Simulink and the experimental setup, a small signal line to line shunt current injection technique is used and the obtained frequency response is then identified into second order systems. Sufficient matching among these results proves the validity of the modelling procedure. Exact impedances of the integral parts, in interconnected AC/DC/AC systems, are required for determining the stability through input-output impedances.

  18. Implications of Sepedi/English code switching for ASR systems

    CSIR Research Space (South Africa)

    Modipa, TI

    2013-12-01

    Full Text Available Code switching (the process of switching from one language to another during a conversation) is a common phenomenon in multilingual environments. Where a minority and dominant language coincide, code switching from the minority language...

  19. 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...

  20. Forward gated-diode method for parameter extraction of MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Chenfei; He Jin; Wang Guozeng; Yang Zhang; Liu Zhiwei [Peking University Shenzhen SOC Key Laboratory, PKU HKUST Shenzhen Institute, Shenzhen 518057 (China); Ma Chenyue; Guo Xinjie; Zhang Xiufang, E-mail: frankhe@pku.edu.cn [TSRC, Institute of Microelectronics, School of Electronic Engineering and Computer Science, Peking University, Beijing 100871 (China)

    2011-02-15

    The forward gated-diode method is used to extract the dielectric oxide thickness and body doping concentration of MOSFETs, especially when both of the variables are unknown previously. First, the dielectric oxide thickness and the body doping concentration as a function of forward gated-diode peak recombination-generation (R-G) current are derived from the device physics. Then the peak R-G current characteristics of the MOSFETs with different dielectric oxide thicknesses and body doping concentrations are simulated with ISE-Dessis for parameter extraction. The results from the simulation data demonstrate excellent agreement with those extracted from the forward gated-diode method. (semiconductor devices)

  1. Photoluminescence excitation measurements using pressure-tuned laser diodes

    Science.gov (United States)

    Bercha, Artem; Ivonyak, Yurii; Medryk, Radosław; Trzeciakowski, Witold A.; Dybała, Filip; Piechal, Bernard

    2015-06-01

    Pressure-tuned laser diodes in external cavity were used as tunable sources for photoluminescence excitation (PLE) spectroscopy. The method was demonstrated in the 720 nm-1070 nm spectral range using a few commercial laser diodes. The samples for PLE measurements were quantum-well structures grown on GaAs and on InP. The method is superior to standard PLE measurements using titanium sapphire laser because it can be extended to any spectral range where anti-reflection coated laser diodes are available.

  2. Photoluminescence excitation measurements using pressure-tuned laser diodes

    International Nuclear Information System (INIS)

    Bercha, Artem; Ivonyak, Yurii; Mędryk, Radosław; Trzeciakowski, Witold A.; Dybała, Filip; Piechal, Bernard

    2015-01-01

    Pressure-tuned laser diodes in external cavity were used as tunable sources for photoluminescence excitation (PLE) spectroscopy. The method was demonstrated in the 720 nm-1070 nm spectral range using a few commercial laser diodes. The samples for PLE measurements were quantum-well structures grown on GaAs and on InP. The method is superior to standard PLE measurements using titanium sapphire laser because it can be extended to any spectral range where anti-reflection coated laser diodes are available

  3. Tapered diode laser pumped 946 nm Nd:YAG laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2009-01-01

    We successfully implemented a 946 nm Nd:YAG laser based on a 808 nm tapered diode pump laser. The tapered diode is developed at the Ferdinand-Braun-Institute fur Hochstfrequenztechnik in Germany. Figure 2 shows the experimental setup and results of each pump source coupled into a 1.5 mm crystal...... laser, we show that tapered diode laser pumping potentially increase the power of 946 nm lasers by a factor of two and reduce the threshold by a factor of three....

  4. Design of all Optical Packet Switching Networks

    Directory of Open Access Journals (Sweden)

    Hussein T. Mouftah

    2002-06-01

    Full Text Available Optical switches and wavelength converters are recognized as two of the most important DWDM system components in future all-optical networks. Optical switches perform the key functions of flexible routing, reconfigurable optical cross-connect (OXC, network protection and restoration, etc. in optical networks. Wavelength Converters are used to shift one incoming wavelength to another outgoing wavelength when this needs to be done.  Always residing in optical switches, they can effectively alleviate the blocking probability and help solve contention happening at the output port of switches. The deployment of wavelength converters within optical switches provides robust routing, switching and network management in optical layer, which is critical to the emerging all-optical Internet. However, the high cost of wavelength converters at current stage of manufacturing technology has to be taken into consideration when we design node architectures for an optical network. Our research explores the efficiency of wavelength converters in a long-haul optical network at different degrees of traffic load by running a simulation. Then, we propose a new cost-effective way to optimally design wavelength-convertible switch so as to achieve higher network performance while still keeping the total network cost down. Meanwhile, the routing and wavelength assignment (RWA algorithm used in the research is designed to be a generic one for both large-scale and small-scale traffic. Removing the constraint on the traffic load makes the RWA more adaptive and robust. When this new RWA works in conjunction with a newly introduced concept of wavelength-convertible switches, we shall explore the impact of large-scale traffic on the role of wavelength converter so as to determine the method towards optimal use of wavelength convertible switches for all-optical networks.

  5. Irradiation of optically activated SI-GaAs high-voltage switches with low and high energy protons

    CERN Document Server

    Bertolucci, Ennio; Mettivier, G; Russo, P; Bisogni, M G; Bottigli, U; Fantacci, M E; Stefanini, A; Cola, A; Quaranta, F; Vasanelli, L; Stefanini, G

    1999-01-01

    Semi-Insulating Gallium Arsenide (SI-GaAs) devices have been tested for radiation hardness with 3-4 MeV or 24 GeV proton beams. These devices can be operated in dc mode as optically activated electrical switches up to 1 kV. Both single switches (vertical Schottky diodes) and multiple (8) switches (planar devices) have been studied, by analyzing their current-voltage (I-V) reverse characteristics in the dark and under red light illumination, both before and after irradiation. We propose to use them in the system of high-voltage (-600 V) switches for the microstrip gas chambers for the CMS experiment at CERN. Low energy protons (3-4 MeV) were used in order to produce a surface damage below the Schottky contact: their fluence (up to 2.6*10/sup 15/ p/cm/sup 2/) gives a high-dose irradiation. The high energy proton irradiation (energy: 24 GeV, fluence: 1.1*10/sup 14/ p/cm/sup 2/) reproduced a ten years long proton exposure of the devices in CMS experiment conditions. For low energy irradiation, limited changes of ...

  6. Comparison of switching control algorithms effective in restricting the switching in the neighborhood of the origin

    International Nuclear Information System (INIS)

    Joung, JinWook; Chung, Lan; Smyth, Andrew W

    2010-01-01

    The active interaction control (AIC) system consisting of a primary structure, an auxiliary structure and an interaction element was proposed to protect the primary structure against earthquakes and winds. The objective of the AIC system in reducing the responses of the primary structure is fulfilled by activating or deactivating the switching between the engagement and the disengagement of the primary and auxiliary structures through the interaction element. The status of the interaction element is controlled by switching control algorithms. The previously developed switching control algorithms require an excessive amount of switching, which is inefficient. In this paper, the excessive amount of switching is restricted by imposing an appropriately designed switching boundary region, where switching is prohibited, on pre-designed engagement–disengagement conditions. Two different approaches are used in designing the newly proposed AID-off and AID-off 2 algorithms. The AID-off 2 algorithm is designed to affect deactivated switching regions explicitly, unlike the AID-off algorithm, which follows the same procedure of designing the engagement–disengagement conditions of the previously developed algorithms, by using the current status of the AIC system. Both algorithms are shown to be effective in reducing the amount of switching times triggered from the previously developed AID algorithm under an appropriately selected control sampling period for different earthquakes, but the AID-off 2 algorithm outperforms the AID-off algorithm in reducing the number of switching times

  7. Organization of the channel-switching process in parallel computer systems based on a matrix optical switch

    Science.gov (United States)

    Golomidov, Y. V.; Li, S. K.; Popov, S. A.; Smolov, V. B.

    1986-01-01

    After a classification and analysis of electronic and optoelectronic switching devices, the design principles and structure of a matrix optical switch is described. The switching and pair-exclusion operations in this type of switch are examined, and a method for the optical switching of communication channels is elaborated. Finally, attention is given to the structural organization of a parallel computer system with a matrix optical switch.

  8. Active stabilization of a diode laser injection lock

    Energy Technology Data Exchange (ETDEWEB)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep [Department of Physics, University of Washington, P.O. Box 351560, Seattle, Washington 98195-1560 (United States)

    2016-06-15

    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.

  9. Failure Analysis of Heavy-Ion-Irradiated Schottky Diodes

    Science.gov (United States)

    Casey, Megan C.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Topper, Alyson D.; Campola, Michael J.; Label, Kenneth A.

    2017-01-01

    In this work, we use high- and low-magnitude optical microscope images, infrared camera images, and scanning electron microscope images to identify and describe the failure locations in heavy-ion-irradiated Schottky diodes.

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

    DEFF Research Database (Denmark)

    Müller, André

    spectroscopy and imaging, and fluorescence measurements. A major challenge in diode laser technology is to obtain high-power laser emission at wavelengths green spectral range is of high importance, for example, in dermatology or for direct pumping of ultrashort pulsed lasers...... in conjunction with optical coherence tomography, two-photon microscopy or coherent anti-Stokes Raman scattering microscopy. In order to provide high-power green diode laser emission, nonlinear frequency conversion of state-of-the-art near-infrared diode lasers represents a necessary means. However, the obtained...... output power of frequency doubled single emitters is limited by thermal effects potentially resulting in laser degradation and failure. In this work new concepts for power scaling of visible diode laser systems are introduced that help to overcome current limitations and enhance the application potential...

  11. An all MMIC Replacement for Gunn Diode Oscillators, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to replace the Gunn Diode Oscillators (GDOs) in NASA?s millimeter- and submillimeter-wave sensing instruments. Our new solution will rely on modern and...

  12. 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.

  13. 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.

  14. Effect of different diode laser powers in photodynamic therapy

    CSIR Research Space (South Africa)

    Maduray, K

    2010-09-01

    Full Text Available This preliminary photodynamic therapy study investigated the effect of different diode laser powers (mW) for the activation of two photosensitizers (AlTSPc, aluminum tetrasulfonatedphthalocyanine and ZnTSPc, zinc tetrasulfonatedphthalocyanine...

  15. 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

  16. Unmanned Aerial Vehicle Diode Laser Sensor for Methane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A compact, lightweight, and low power diode laser sensor will be developed for atmospheric methane detection on small unmanned aerial vehicles (UAVs). The physical...

  17. Active stabilization of a diode laser injection lock

    International Nuclear Information System (INIS)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; 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.

  18. Analysis and Optimization of "Full-Length" Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Schock, Alfred

    2012-01-19

    A method of analyzing the axial variation of the heat generation rate, temperature, voltage, current density and emitter heat flux in a thermionic converter is described. The method is particularly useful for the case of "long" diodes, each extending over the full length of the reactor core. For a given diode geometry and fuel distribution, the analysis combines a nuclear solution of the axial fission density profile with the iterative solution of four differential equations representing the thermal, electrical, and thermionic interactions within the diode. The digital computer program developed to solve these equations can also perform a design optimization with respect to lead resistance, load voltage, and emitter thickness, for a specified maximum emitter temperature. Typical results are presented, and the use of this analysis for predicting the diode operating characteristics is illustrated.

  19. Fault tolerant control for switched linear systems

    CERN Document Server

    Du, Dongsheng; Shi, Peng

    2015-01-01

    This book presents up-to-date research and novel methodologies on fault diagnosis and fault tolerant control for switched linear systems. It provides a unified yet neat framework of filtering, fault detection, fault diagnosis and fault tolerant control of switched systems. It can therefore serve as a useful textbook for senior and/or graduate students who are interested in knowing the state-of-the-art of filtering, fault detection, fault diagnosis and fault tolerant control areas, as well as recent advances in switched linear systems.  

  20. Consumer poaching, brand switching, and price transparency

    DEFF Research Database (Denmark)

    Schultz, Christian

    2014-01-01

    This paper addresses price transparency on the consumer side in markets with behavioral price discrimination which feature welfare reducing brand switching. When long-term contracts are not available, an increase in transparency intensifies competition, lowers prices and profits, reduces brand...... switching and benefits consumers and welfare. With long-term contracts, an increase in transparency reduces the use of long-term contracts, leading to more brand switching and a welfare loss. Otherwise, the results are the same as without long-term contracts....