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Sample records for switches mechanical

  1. 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.

  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. 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.

  4. The operational mechanism of ferroelectric-driven organic resistive switches

    NARCIS (Netherlands)

    Kemerink, M.; Asadi, K.; Blom, P.W.M.; Leeuw, D.M. de

    2012-01-01

    The availability of a reliable memory element is crucial for the fabrication of 'plastic' logic circuits. We use numerical simulations to show that the switching mechanism of ferroelectric-driven organic resistive switches is the stray field of the polarized ferroelectric phase. The stray field

  5. The operational mechanism of ferroelectric-driven organic resistive switches

    NARCIS (Netherlands)

    Kemerink, Martijn; Asadi, Kamal; Blom, Paul W. M.; de Leeuw, Dago M.

    The availability of a reliable memory element is crucial for the fabrication of 'plastic' logic circuits. We use numerical simulations to show that the switching mechanism of ferroelectric-driven organic resistive switches is the stray field of the polarized ferroelectric phase. The stray field

  6. Conduction Mechanism of Valence Change Resistive Switching Memory: A Survey

    Directory of Open Access Journals (Sweden)

    Ee Wah Lim

    2015-09-01

    Full Text Available Resistive switching effect in transition metal oxide (TMO based material is often associated with the valence change mechanism (VCM. Typical modeling of valence change resistive switching memory consists of three closely related phenomena, i.e., conductive filament (CF geometry evolution, conduction mechanism and temperature dynamic evolution. It is widely agreed that the electrochemical reduction-oxidation (redox process and oxygen vacancies migration plays an essential role in the CF forming and rupture process. However, the conduction mechanism of resistive switching memory varies considerably depending on the material used in the dielectric layer and selection of electrodes. Among the popular observations are the Poole-Frenkel emission, Schottky emission, space-charge-limited conduction (SCLC, trap-assisted tunneling (TAT and hopping conduction. In this article, we will conduct a survey on several published valence change resistive switching memories with a particular interest in the I-V characteristic and the corresponding conduction mechanism.

  7. A novel RF MEMS switch with novel mechanical structure modeling

    International Nuclear Information System (INIS)

    Chan, K Y; Ramer, R

    2010-01-01

    A novel RF MEMS contact-type switch for RF and microwave applications is presented. The switch is designed with special mechanical structures for stiffness enhancement. A method of using dimple lines to reduce the stress sensitivity of a beam is shown with complete mathematical modeling and finite element mechanical simulation. A complete mathematical model is developed for the proposed switch. Limited fabrication resolution and non-uniformities in layer thickness and stress were taken into consideration for this design, concomitantly with the preservation of device miniaturization and functionalities. The novel mechanical modeling of the switch leads to the estimation of the actuation voltage and shows simplification from previously published analysis. The measured actuation voltage and RF performance of the novel RF MEMS switch are also reported. The switch actuated at 20 V achieved better than 22 dB return loss and less than 0.7 dB insertion loss in on state from dc–40 GHz; it provided better than 30 dB isolation in off state

  8. Nanoscale mechanical switching of ferroelectric polarization via flexoelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Yijia; Hong, Zijian; Britson, Jason; Chen, Long-Qing [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-01-12

    Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide an understanding of the role of flexoelectricity in the polarization switching. Also, by changing the pressure and film thickness, we reveal that the flexoelectric field at the film bottom can be used as a criterion to determine whether domain switching may happen under a mechanical force.

  9. Nanoscale mechanical switching of ferroelectric polarization via flexoelectricity

    International Nuclear Information System (INIS)

    Gu, Yijia; Hong, Zijian; Britson, Jason; Chen, Long-Qing

    2015-01-01

    Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide an understanding of the role of flexoelectricity in the polarization switching. Also, by changing the pressure and film thickness, we reveal that the flexoelectric field at the film bottom can be used as a criterion to determine whether domain switching may happen under a mechanical force

  10. Nanoscale mechanical switching of ferroelectric polarization via flexoelectricity

    Science.gov (United States)

    Gu, Yijia; Hong, Zijian; Britson, Jason; Chen, Long-Qing

    2015-01-01

    Flexoelectric coefficient is a fourth-rank tensor arising from the coupling between strain gradient and electric polarization and thus exists in all crystals. It is generally ignored for macroscopic crystals due to its small magnitude. However, at the nanoscale, flexoelectric contributions may become significant and can potentially be utilized for device applications. Using the phase-field method, we study the mechanical switching of electric polarization in ferroelectric thin films by a strain gradient created via an atomic force microscope tip. Our simulation results show good agreement with existing experimental observations. We examine the competition between the piezoelectric and flexoelectric effects and provide an understanding of the role of flexoelectricity in the polarization switching. Also, by changing the pressure and film thickness, we reveal that the flexoelectric field at the film bottom can be used as a criterion to determine whether domain switching may happen under a mechanical force.

  11. Experiments on microsecond conduction time plasma opening switch mechanisms

    International Nuclear Information System (INIS)

    Rix, W.; Coleman, M.; Miller, A.R.; Parks, D.; Robertson, K.; Thompson, J.; Waisman, E.; Wilson, A.

    1993-01-01

    The authors describe a series of experiments carried out on ACE 2 and ACE 4 to elucidate the mechanisms controlling the conduction and opening phases on plasma opening switches in a radial geometry with conduction times on the order of a microsecond. The results indicate both conduction and opening physics are similar to that observed on lower current systems in a coaxial geometry

  12. The allosteric switching mechanism in bacteriophage MS2

    Science.gov (United States)

    Perkett, Matthew R.; Mirijanian, Dina T.; Hagan, Michael F.

    2016-07-01

    We use all-atom simulations to elucidate the mechanisms underlying conformational switching and allostery within the coat protein of the bacteriophage MS2. Assembly of most icosahedral virus capsids requires that the capsid protein adopts different conformations at precise locations within the capsid. It has been shown that a 19 nucleotide stem loop (TR) from the MS2 genome acts as an allosteric effector, guiding conformational switching of the coat protein during capsid assembly. Since the principal conformational changes occur far from the TR binding site, it is important to understand the molecular mechanism underlying this allosteric communication. To this end, we use all-atom simulations with explicit water combined with a path sampling technique to sample the MS2 coat protein conformational transition, in the presence and absence of TR-binding. The calculations find that TR binding strongly alters the transition free energy profile, leading to a switch in the favored conformation. We discuss changes in molecular interactions responsible for this shift. We then identify networks of amino acids with correlated motions to reveal the mechanism by which effects of TR binding span the protein. We find that TR binding strongly affects residues located at the 5-fold and quasi-sixfold interfaces in the assembled capsid, suggesting a mechanism by which the TR binding could direct formation of the native capsid geometry. The analysis predicts amino acids whose substitution by mutagenesis could alter populations of the conformational substates or their transition rates.

  13. The allosteric switching mechanism in bacteriophage MS2

    Energy Technology Data Exchange (ETDEWEB)

    Perkett, Matthew R.; Mirijanian, Dina T.; Hagan, Michael F., E-mail: hagan@brandeis.edu [Martin Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02474 (United States)

    2016-07-21

    We use all-atom simulations to elucidate the mechanisms underlying conformational switching and allostery within the coat protein of the bacteriophage MS2. Assembly of most icosahedral virus capsids requires that the capsid protein adopts different conformations at precise locations within the capsid. It has been shown that a 19 nucleotide stem loop (TR) from the MS2 genome acts as an allosteric effector, guiding conformational switching of the coat protein during capsid assembly. Since the principal conformational changes occur far from the TR binding site, it is important to understand the molecular mechanism underlying this allosteric communication. To this end, we use all-atom simulations with explicit water combined with a path sampling technique to sample the MS2 coat protein conformational transition, in the presence and absence of TR-binding. The calculations find that TR binding strongly alters the transition free energy profile, leading to a switch in the favored conformation. We discuss changes in molecular interactions responsible for this shift. We then identify networks of amino acids with correlated motions to reveal the mechanism by which effects of TR binding span the protein. We find that TR binding strongly affects residues located at the 5-fold and quasi-sixfold interfaces in the assembled capsid, suggesting a mechanism by which the TR binding could direct formation of the native capsid geometry. The analysis predicts amino acids whose substitution by mutagenesis could alter populations of the conformational substates or their transition rates.

  14. Floating electrode microelectromechanical system capacitive switches: A different actuation mechanism

    Science.gov (United States)

    Papaioannou, G.; Giacomozzi, F.; Papandreou, E.; Margesin, B.

    2011-08-01

    The paper investigates the actuation mechanism in floating electrode microelectromechanical system capacitive switches. It is demonstrated that in the pull-in state, the device operation turns from voltage to current controlled actuation. The current arises from Poole-Frenkel mechanism in the dielectric film and Fowler-Nordheim in the bridge-floating electrode air gap. The pull-out voltage seems to arise from the abrupt decrease of Fowler-Nordheim electric field intensity. This mechanism seems to be responsible for the very small difference with respect to the pull-in voltage.

  15. Acoustic emission mechanism at switching of ferroelectric crystals

    International Nuclear Information System (INIS)

    Belov, V.V.; Morozova, G.P.; Serdobol'skaya, O.Yu.

    1986-01-01

    Process of acoustic emission (AE) in lead germanate (PGO) representing pure ferroelectric, and gadolinium molybdate (GMO) representing ferroelectric-ferroelastic, for which switching may be conducted both by the field and pressure, were studied. A conclusion has been drawn that piezoelectric excitation of a crystal from the surface by pulses of overpolarization current in the process of domain coalescence is the main AE source in PGO. Not only piezoresponse, but also direct sound generation in the moment of domain penetration and collapse is considered as AE mechanism in GMO

  16. Analysis and modeling of resistive switching mechanisms oriented to resistive random-access memory

    International Nuclear Information System (INIS)

    Huang Da; Wu Jun-Jie; Tang Yu-Hua

    2013-01-01

    With the progress of the semiconductor industry, the resistive random-access memory (RAM) has drawn increasing attention. The discovery of the memristor has brought much attention to this study. Research has focused on the resistive switching characteristics of different materials and the analysis of resistive switching mechanisms. We discuss the resistive switching mechanisms of different materials in this paper and analyze the differences of those mechanisms from the view point of circuitry to establish their respective circuit models. Finally, simulations are presented. We give the prospect of using different materials in resistive RAM on account of their resistive switching mechanisms, which are applied to explain their resistive switchings

  17. Determination of the mechanical thermostat electrical contacts switching quality with sound and vibration analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rejc, Jure; Munih, Marko [University of Ljubljana, Ljubljana (Slovenia)

    2017-05-15

    A mechanical thermostat is a device that switches heating or cooling appliances on or off based on temperature. For this kind of use, electronic or mechanical switching concepts are applied. During the production of electrical contacts, several irregularities can occur leading to improper switching events of the thermostat electrical contacts. This paper presents a non-obstructive method based on the fact that when the switching event occurs it can be heard and felt by human senses. We performed several laboratory tests with two different methods. The first method includes thermostat switch sound signal analysis during the switching event. The second method is based on sampling of the accelerometer signal during the switching event. The results show that the sound analysis approach has great potential. The approach enables an accurate determination of the switching event even if the sampled signal carries also the switching event of the neighbour thermostat.

  18. Locally-Actuated Graphene-Based Nano-Electro-Mechanical Switch

    Directory of Open Access Journals (Sweden)

    Jian Sun

    2016-07-01

    Full Text Available The graphene nano-electro-mechanical switches are promising components due to their outstanding switching performance. However, most of the reported devices suffered from a large actuation voltages, hindering them from the integration in the conventional complementary metal-oxide-semiconductor (CMOS circuit. In this work, we demonstrated the graphene nano-electro-mechanical switches with the local actuation electrode via conventional nanofabrication techniques. Both cantilever-type and double-clamped beam switches were fabricated. These devices exhibited the sharp switching, reversible operation cycles, high on/off ratio, and a low actuation voltage of below 5 V, which were compatible with the CMOS circuit requirements.

  19. Switching hierarchical leadership mechanism in homing flight of pigeon flocks

    Science.gov (United States)

    Chen, Duxin; Vicsek, Tamás; Liu, Xiaolu; Zhou, Tao; Zhang, Hai-Tao

    2016-06-01

    To explore the fascinating inter-individual interaction mechanism governing the abundant biological grouping behaviors, more and more efforts have been devoted to collective motion investigation in recent years. Therein, bird flocking is one of the most intensively studied behaviors. A previous study (Nagy M. et al., Nature, 464 (2010) 890.) claims the existence of a well-defined hierarchical structure in pigeon flocks, which implies that a multi-layer leadership network leads to the occurrence of highly coordinated pigeon flock movements. However, in this study, by using high-resolution GPS data of homing flight of pigeon flocks, we reveal an explicit switching hierarchical mechanism underlying the group motions of pigeons. That is, a pigeon flock has a long-term leader for smooth moving trajectories, whereas the leading tenure passes to a temporary one upon sudden turns or zigzags. Therefore, the present observation helps explore more deeply into the principle of a huge volume of bird flocking dynamics. Meanwhile, from the engineering point of view, it may shed some light onto industrial multi-robot coordination and unmanned air vehicle formation control.

  20. Switching on elusive organometallic mechanisms with photoredox catalysis.

    Science.gov (United States)

    Terrett, Jack A; Cuthbertson, James D; Shurtleff, Valerie W; MacMillan, David W C

    2015-08-20

    Transition-metal-catalysed cross-coupling reactions have become one of the most used carbon-carbon and carbon-heteroatom bond-forming reactions in chemical synthesis. Recently, nickel catalysis has been shown to participate in a wide variety of C-C bond-forming reactions, most notably Negishi, Suzuki-Miyaura, Stille, Kumada and Hiyama couplings. Despite the tremendous advances in C-C fragment couplings, the ability to forge C-O bonds in a general fashion via nickel catalysis has been largely unsuccessful. The challenge for nickel-mediated alcohol couplings has been the mechanistic requirement for the critical C-O bond-forming step (formally known as the reductive elimination step) to occur via a Ni(III) alkoxide intermediate. Here we demonstrate that visible-light-excited photoredox catalysts can modulate the preferred oxidation states of nickel alkoxides in an operative catalytic cycle, thereby providing transient access to Ni(III) species that readily participate in reductive elimination. Using this synergistic merger of photoredox and nickel catalysis, we have developed a highly efficient and general carbon-oxygen coupling reaction using abundant alcohols and aryl bromides. More notably, we have developed a general strategy to 'switch on' important yet elusive organometallic mechanisms via oxidation state modulations using only weak light and single-electron-transfer catalysts.

  1. Robust switched PI controller design for a simple hysteretic mechanical system

    NARCIS (Netherlands)

    Jayawardhana, B.

    2010-01-01

    In this paper, we consider the design of a robust switched PI controller for a simple hysteretic mechanical system. The design procedure ensures that the closed-loop system remains inputto-state stable under arbitrary switching signals among a family of PI controllers, it has an exponential

  2. Controlled switching of single-molecule junctions by mechanical motion of a phenyl ring

    Directory of Open Access Journals (Sweden)

    Yuya Kitaguchi

    2015-10-01

    Full Text Available Mechanical methods for single-molecule control have potential for wide application in nanodevices and machines. Here we demonstrate the operation of a single-molecule switch made functional by the motion of a phenyl ring, analogous to the lever in a conventional toggle switch. The switch can be actuated by dual triggers, either by a voltage pulse or by displacement of the electrode, and electronic manipulation of the ring by chemical substitution enables rational control of the on-state conductance. Owing to its simple mechanics, structural robustness, and chemical accessibility, we propose that phenyl rings are promising components in mechanical molecular devices.

  3. Macro-mechanics controls quantum mechanics: mechanically controllable quantum conductance switching of an electrochemically fabricated atomic-scale point contact.

    Science.gov (United States)

    Staiger, Torben; Wertz, Florian; Xie, Fangqing; Heinze, Marcel; Schmieder, Philipp; Lutzweiler, Christian; Schimmel, Thomas

    2018-01-12

    Here, we present a silver atomic-scale device fabricated and operated by a combined technique of electrochemical control (EC) and mechanically controllable break junction (MCBJ). With this EC-MCBJ technique, we can perform mechanically controllable bistable quantum conductance switching of a silver quantum point contact (QPC) in an electrochemical environment at room temperature. Furthermore, the silver QPC of the device can be controlled both mechanically and electrochemically, and the operating mode can be changed from 'electrochemical' to 'mechanical', which expands the operating mode for controlling QPCs. These experimental results offer the perspective that a silver QPC may be used as a contact for a nanoelectromechanical relay.

  4. The mechanism of electroforming of metal oxide memristive switches

    Science.gov (United States)

    Joshua Yang, J.; Miao, Feng; Pickett, Matthew D.; Ohlberg, Douglas A. A.; Stewart, Duncan R.; Lau, Chun Ning; Williams, R. Stanley

    2009-05-01

    Metal and semiconductor oxides are ubiquitous electronic materials. Normally insulating, oxides can change behavior under high electric fields—through 'electroforming' or 'breakdown'—critically affecting CMOS (complementary metal-oxide-semiconductor) logic, DRAM (dynamic random access memory) and flash memory, and tunnel barrier oxides. An initial irreversible electroforming process has been invariably required for obtaining metal oxide resistance switches, which may open urgently needed new avenues for advanced computer memory and logic circuits including ultra-dense non-volatile random access memory (NVRAM) and adaptive neuromorphic logic circuits. This electrical switching arises from the coupled motion of electrons and ions within the oxide material, as one of the first recognized examples of a memristor (memory-resistor) device, the fourth fundamental passive circuit element originally predicted in 1971 by Chua. A lack of device repeatability has limited technological implementation of oxide switches, however. Here we explain the nature of the oxide electroforming as an electro-reduction and vacancy creation process caused by high electric fields and enhanced by electrical Joule heating with direct experimental evidence. Oxygen vacancies are created and drift towards the cathode, forming localized conducting channels in the oxide. Simultaneously, O2- ions drift towards the anode where they evolve O2 gas, causing physical deformation of the junction. The problematic gas eruption and physical deformation are mitigated by shrinking to the nanoscale and controlling the electroforming voltage polarity. Better yet, electroforming problems can be largely eliminated by engineering the device structure to remove 'bulk' oxide effects in favor of interface-controlled electronic switching.

  5. Charge transport and bipolar switching mechanism in a Cu/HfO2/Pt resistive switching cell

    International Nuclear Information System (INIS)

    Tan Tingting; Guo Tingting; Wu Zhihui; Liu Zhengtang

    2016-01-01

    Bipolar resistance switching characteristics are investigated in Cu/sputtered-HfO 2 /Pt structure in the application of resistive random access memory (RRAM). The conduction mechanism of the structure is characterized to be SCLC conduction. The dependence of resistances in both high resistance state (HRS) and low resistance state (LRS) on the temperature and device area are studied. Then, the composition and chemical bonding state of Cu and Hf at Cu/HfO 2 interface region are analyzed by x-ray photoelectron spectroscopy (XPS). Combining the electrical characteristics and the chemical structure at the interface, a model for the resistive switching effect in Cu/HfO 2 /Pt stack is proposed. According to this model, the generation and recovery of oxygen vacancies in the HfO 2 film are responsible for the resistance change. (paper)

  6. Common and Distinct Neural Mechanisms of Attentional Switching and Response Conflict

    Science.gov (United States)

    Kim, Chobok; Johnson, Nathan F.; Gold, Brian T.

    2012-01-01

    The human capacities for overcoming prepotent actions and flexibly switching between tasks represent cornerstones of cognitive control. Functional neuroimaging has implicated a diverse set of brain regions contributing to each of these cognitive control processes. However, the extent to which attentional switching and response conflict draw on shared or distinct neural mechanisms remains unclear. The current study examined the neural correlates of response conflict and attentional switching using event-related functional magnetic resonance imaging (fMRI) and a fully randomized 2×2 design. We manipulated an arrow-word version of the Stroop task to measure conflict and switching in the context of a single task decision, in response to a common set of stimuli. Under these common conditions, both behavioral and imaging data showed significant main effects of conflict and switching but no interaction. However, conjunction analyses identified frontal regions involved in both switching and response conflict, including the dorsal anterior cingulate cortex (dACC) and left inferior frontal junction. In addition, connectivity analyses demonstrated task-dependent functional connectivity patterns between dACC and inferior temporal cortex for attentional switching and between dACC and posterior parietal cortex for response conflict. These results suggest that the brain makes use of shared frontal regions, but can dynamically modulate the connectivity patterns of some of those regions, to deal with attentional switching and response conflict. PMID:22750124

  7. Conducting mechanism of Ag-diffused Bi-Te based resistive switching devices

    Science.gov (United States)

    Liu, N.; Yan, P.; Li, Y.; Lu, K.; Sun, H. J.; Ji, H. K.; Xue, K. H.; Miao, X. S.

    2018-02-01

    The forming-free resistive switching (RS) and conducting mechanism of Ag-diffused BiTe chalcogenide thin film has been investigated. The mutual diffusion of Ag, Bi and Te elements at the interface is proved to suppress the crystallization of the as-deposited BiTe film. The amorphization of BiTe and the Schottky barrier between Ag and BiTe contribute to high resistance state (HRS) of the switching devices. When switched to low resistance state (LRS), the coexistence of metallic conduction and variable-range hopping is found to be the dominant conduction mechanism. The temperature dependence of LRS exhibits an interesting transport behavior, so that a positive temperature coefficient becomes a negative one at 24 K. Our results help to further understand the conduction mechanism and promote the design for future nonvolatile memory applications.

  8. Isomerization mechanism in hydrazone-based rotary switches: lateral shift, rotation, or tautomerization?

    Science.gov (United States)

    Landge, Shainaz M; Tkatchouk, Ekatarina; Benítez, Diego; Lanfranchi, Don Antoine; Elhabiri, Mourad; Goddard, William A; Aprahamian, Ivan

    2011-06-29

    Two intramolecularly hydrogen-bonded arylhydrazone (aryl = phenyl or naphthyl) molecular switches have been synthesized, and their full and reversible switching between the E and Z configurations have been demonstrated. These chemically controlled configurational rotary switches exist primarily as the E isomer at equilibrium and can be switched to the protonated Z configuration (Z-H(+)) by the addition of trifluoroacetic acid. The protonation of the pyridine moiety in the switch induces a rotation around the hydrazone C=N double bond, leading to isomerization. Treating Z-H(+) with base (K(2)CO(3)) yields a mixture of E and "metastable" Z isomers. The latter thermally equilibrates to reinstate the initial isomer ratio. The rate of the Z → E isomerization process showed small changes as a function of solvent polarity, indicating that the isomerization might be going through the inversion mechanism (nonpolar transition state). However, the plot of the logarithm of the rate constant k vs the Dimroth parameter (E(T)) gave a linear fit, demonstrating the involvement of a polar transition state (rotation mechanism). These two seemingly contradicting kinetic data were not enough to determine whether the isomerization mechanism goes through the rotation or inversion pathways. The highly negative entropy values obtained for both the forward (E → Z-H(+)) and backward (Z → E) processes strongly suggest that the isomerization involves a polarized transition state that is highly organized (possibly involving a high degree of solvent organization), and hence it proceeds via a rotation mechanism as opposed to inversion. Computations of the Z ↔ E isomerization using density functional theory (DFT) at the M06/cc-pVTZ level and natural bond orbital (NBO) wave function analyses have shown that the favorable isomerization mechanism in these hydrogen-bonded systems is hydrazone-azo tautomerization followed by rotation around a C-N single bond, as opposed to the more common

  9. DNA-Binding Kinetics Determines the Mechanism of Noise-Induced Switching in Gene Networks.

    Science.gov (United States)

    Tse, Margaret J; Chu, Brian K; Roy, Mahua; Read, Elizabeth L

    2015-10-20

    Gene regulatory networks are multistable dynamical systems in which attractor states represent cell phenotypes. Spontaneous, noise-induced transitions between these states are thought to underlie critical cellular processes, including cell developmental fate decisions, phenotypic plasticity in fluctuating environments, and carcinogenesis. As such, there is increasing interest in the development of theoretical and computational approaches that can shed light on the dynamics of these stochastic state transitions in multistable gene networks. We applied a numerical rare-event sampling algorithm to study transition paths of spontaneous noise-induced switching for a ubiquitous gene regulatory network motif, the bistable toggle switch, in which two mutually repressive genes compete for dominant expression. We find that the method can efficiently uncover detailed switching mechanisms that involve fluctuations both in occupancies of DNA regulatory sites and copy numbers of protein products. In addition, we show that the rate parameters governing binding and unbinding of regulatory proteins to DNA strongly influence the switching mechanism. In a regime of slow DNA-binding/unbinding kinetics, spontaneous switching occurs relatively frequently and is driven primarily by fluctuations in DNA-site occupancies. In contrast, in a regime of fast DNA-binding/unbinding kinetics, switching occurs rarely and is driven by fluctuations in levels of expressed protein. Our results demonstrate how spontaneous cell phenotype transitions involve collective behavior of both regulatory proteins and DNA. Computational approaches capable of simulating dynamics over many system variables are thus well suited to exploring dynamic mechanisms in gene networks. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  10. Switch telomerase to ALT mechanism by inducing telomeric DNA damages and dysfunction of ATRX and DAXX.

    Science.gov (United States)

    Hu, Yang; Shi, Guang; Zhang, Laichen; Li, Feng; Jiang, Yuanling; Jiang, Shuai; Ma, Wenbin; Zhao, Yong; Songyang, Zhou; Huang, Junjiu

    2016-08-31

    Activation of telomerase or alternative lengthening of telomeres (ALT) is necessary for tumours to escape from dysfunctional telomere-mediated senescence. Anti-telomerase drugs might be effective in suppressing tumour growth in approximately 85-90% of telomerase-positive cancer cells. However, there are still chances for these cells to bypass drug treatment after switching to the ALT mechanism to maintain their telomere integrity. But the mechanism underlying this switch is unknown. In this study, we used telomerase-positive cancer cells (HTC75) to discover the mechanism of the telomerase-ALT switch by inducing telomere-specific DNA damage, alpha-thalassemia X-linked syndrome protein (ATRX) knockdown and deletion of death associated protein (DAXX). Surprisingly, two important ALT hallmarks in the ALT-like HTC75 cells were observed after treatments: ALT-associated promyelocytic leukaemia bodies (APBs) and extrachromosomal circular DNA of telomeric repeats. Moreover, knocking out hTERT by utilizing the CRISPR/Cas9 technique led to telomere elongation in a telomerase-independent manner in ALT-like HTC75 cells. In summary, this is the first report to show that inducing telomeric DNA damage, disrupting the ATRX/DAXX complex and inhibiting telomerase activity in telomerase-positive cancer cells lead to the ALT switch.

  11. Resistive switching properties and physical mechanism of europium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Wei; Zou, Changwei [School of Physical Science and Technology, Lingnan Normal University, Zhanjiang (China); Bao, Dinghua [State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou (China)

    2017-09-15

    A forming-free resistive switching effect was obtained in Pt/Eu{sub 2}O{sub 3}/Pt devices in which the Eu{sub 2}O{sub 3} thin films were fabricated by a chemical solution deposition method. The devices show unipolar resistive switching with excellent switching parameters, such as high resistance ratio (10{sup 7}), stable resistance values (read at 0.2 V), low reset voltage, good endurance, and long retention time (up to 10{sup 4} s). On the basis of the analysis of the current-voltage (I-V) curves and the resistance-temperature dependence, it can be concluded that the dominant conducting mechanisms were ohmic behavior and Schottky emission at low resistance state and high resistance state, respectively. The resistive switching behavior could be explained by the formation and rupture of conductive filament, which is related to the abundant oxygen vacancies generated in the deposition process. This work demonstrates the great potential opportunities of Eu{sub 2}O{sub 3} thin film in resistive switching memory applications, which might possess distinguished properties. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Kinetics of Domain Switching by Mechanical and Electrical Stimulation in Relaxor-Based Ferroelectrics

    Science.gov (United States)

    Chen, Zibin; Hong, Liang; Wang, Feifei; An, Xianghai; Wang, Xiaolin; Ringer, Simon; Chen, Long-Qing; Luo, Haosu; Liao, Xiaozhou

    2017-12-01

    Ferroelectric materials have been extensively explored for applications in high-density nonvolatile memory devices because of their ferroelectric-ferroelastic domain-switching behavior under electric loading or mechanical stress. However, the existence of ferroelectric and ferroelastic backswitching would cause significant data loss, which affects the reliability of data storage. Here, we apply in situ transmission electron microscopy and phase-field modeling to explore the unique ferroelastic domain-switching kinetics and the origin of this in relaxor-based Pb (Mg1 /3Nb2 /3)O3-33 % PbTiO3 single-crystal pillars under electrical and mechanical stimulations. Results showed that the electric-mechanical hysteresis loop shifted for relaxor-based single-crystal pillars because of the low energy levels of domains in the material and the constraint on the pillars, resulting in various mechanically reversible and irreversible domain-switching states. The phenomenon can potentially be used for advanced bit writing and reading in nonvolatile memories, which effectively overcomes the backswitching problem and broadens the types of ferroelectric materials for nonvolatile memory applications.

  13. A new coupling mechanism between two graphene electron waveguides for ultrafast switching

    Science.gov (United States)

    Huang, Wei; Liang, Shi-Jun; Kyoseva, Elica; Ang, Lay Kee

    2018-03-01

    In this paper, we report a novel coupling between two graphene electron waveguides, in analogy the optical waveguides. The design is based on the coherent quantum mechanical tunneling of Rabi oscillation between the two graphene electron waveguides. Based on this coupling mechanism, we propose that it can be used as an ultrafast electronic switching device. Based on a modified coupled mode theory, we construct a theoretical model to analyze the device characteristics, and predict that the switching speed is faster than 1 ps and the on–off ratio exceeds 106. Due to the long mean free path of electrons in graphene at room temperature, the proposed design avoids the limitation of low temperature operation required in the traditional design by using semiconductor quantum-well structure. The layout of our design is similar to that of a standard complementary metal-oxide-semiconductor transistor that should be readily fabricated with current state-of-art nanotechnology.

  14. Non-switching to switching transferring mechanism investigation for Ag/SiO x /p-Si structure with SiO x deposited by HWCVD

    Science.gov (United States)

    Liu, Yanhong; Wang, Ruoying; Li, Zhongyue; Wang, Song; Huang, Yang; Peng, Wei

    2018-04-01

    We proposed and fabricated an Ag/SiO x /p-Si sandwich structure, in which amorphous SiO x films were deposited through hot wire chemical vapor deposition (HWCVD) using tetraethylorthosilicate (TEOS) as Si and O precursor. Experimental results indicate that the I–V properties of this structure transfer from non-switching to switching operation as the SiO x deposition temperature increased. The device with SiO x deposited at high deposition temperature exhibits typical bipolar switching properties, which can be potentially used in resistive switching random accessible memory (RRAM). The transferring mechanism from non-switching to switching can be ascribed to the change of structural and electronic properties of SiO x active layer deposited at different temperatures, as evidenced by analyzing FTIR spectrum and fitting its I–V characteristics curves. This work demonstrates a safe and practicable low-temperature device-grade SiO x film deposition technology by conducting HWCVD from TEOS.

  15. A mechanical switch device made of a polyimide-coated microfibrillated cellulose sheet

    Science.gov (United States)

    Couderc, S.; Ducloux, O.; Kim, B. J.; Someya, T.

    2009-05-01

    This paper covers innovative results on the development of an electrostatically actuated mechanical switch device made of a microfibrillated cellulose sheet coated with a thin polyimide layer. For microelectronic applications, biodegradable and biocompatible nanomaterials such as microfibrillated cellulose (MFC) have attracted attention. The studied MFC sheets reveal a fibrous-like morphology composed of cellulose nanofibres leading to a high surface roughness. Moreover, the porous microstructure and the hydrophilic nature of the MFC sheet induce poor dielectric properties. These shortcomings make MFC sheets relatively unsuitable for electronic applications. In order to overcome these drawbacks, both sides of the MFC sheet are coated with a thin polyimide layer, which greatly improves the dielectric properties, moisture sensitivity and sheet surface roughness. This new sheet is then patterned in order to be used as a substrate for the fabrication of a micromechanical switch. Gold electrodes are added onto the sheet for electrostatic actuation and switch detection. The pull-down voltage of this switch, defined as the actuation voltage needed to establish a contact between the free end of the cantilever beam and the substrate, is measured to be about 55 V.

  16. Common mechanics of mode switching in locomotion of limbless and legged animals

    Science.gov (United States)

    Kuroda, Shigeru; Kunita, Itsuki; Tanaka, Yoshimi; Ishiguro, Akio; Kobayashi, Ryo; Nakagaki, Toshiyuki

    2014-01-01

    Crawling using muscular waves is observed in many species, including planaria, leeches, nemertea, aplysia, snails, chitons, earthworms and maggots. Contraction or extension waves propagate along the antero-posterior axis of the body as the crawler pushes the ground substratum backward. However, the observation that locomotory waves can be directed forward or backward has attracted much attention over the past hundred years. Legged organisms such as centipedes and millipedes exhibit parallel phenomena; leg tips form density waves that propagate backward or forward. Mechanical considerations reveal that leg-density waves play a similar role to locomotory waves in limbless species, and that locomotory waves are used by a mechanism common to both legged and limbless species to achieve crawling. Here, we report that both mode switching of the wave direction and friction control were achieved when backward motion was induced in the laboratory. We show that the many variations of switching in different animals can essentially be classified in two types according to mechanical considerations. We propose that during their evolution, limbless crawlers first moved in a manner similar to walking before legs were obtained. Therefore, legged crawlers might have learned the mechanical mode of movement involved in walking long before obtaining legs. PMID:24718452

  17. Mechanical Switching of Aromaticity and Homoaromaticity in Molecular Optical Force Sensors for Polymers.

    Science.gov (United States)

    Stauch, Tim

    2018-03-25

    The sensing of mechanical stress in polymers is indispensable for investigating the origin and propagation of cracks that lead to material failure and for designing mechanically responsive polymers. Here the unique approaches of using the force-induced switching of aromaticity and homoaromaticity in molecular optical force sensors for the real time measurement of mechanical forces acting in stretched polymers are suggested. The mechanical switching of aromaticity in Dewar benzene is an irreversible event, whereas the degree of pi-orbital overlap in homoaromatic compounds like homotropylium can be adjusted progressively over a wide range of forces. Using computational methods, it is demonstrated that both approaches lead to significant changes in the visible part of the UV/VIS spectra of the force sensors upon application of weak forces (pN-nN). Polymers that incorporate such molecular force sensors therefore change their color well before material failure occurs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Switching deformation mode and mechanisms during subduction of continental crust: a case study from Alpine Corsica

    Directory of Open Access Journals (Sweden)

    G. Molli

    2017-07-01

    Full Text Available The switching in deformation mode (from distributed to localized and mechanisms (viscous versus frictional represent a relevant issue in the frame of crustal deformation, being also connected with the concept of the brittle–ductile transition and seismogenesis. In a subduction environment, switching in deformation mode and mechanisms and scale of localization may be inferred along the subduction interface, in a transition zone between the highly coupled (seismogenic zone and decoupled deeper aseismic domain (stable slip. However, the role of brittle precursors in nucleating crystal-plastic shear zones has received more and more consideration being now recognized as fundamental in some cases for the localization of deformation and shear zone development, thus representing a case in which switching deformation mechanisms and scale and style of localization (deformation mode interact and relate to each other. This contribution analyses an example of a millimetre-scale shear zone localized by brittle precursor formed within a host granitic protomylonite. The studied structures, developed in ambient pressure–temperature (P–T conditions of low-grade blueschist facies (temperature T of ca. 300 °C and pressure P ≥ 0. 70 GPa during involvement of Corsican continental crust in the Alpine subduction. We used a multidisciplinary approach by combining detailed microstructural and petrographic analyses, crystallographic preferred orientation by electron backscatter diffraction (EBSD, and palaeopiezometric studies on a selected sample to support an evolutionary model and deformation path for subducted continental crust. We infer that the studied structures, possibly formed by transient instability associated with fluctuations of pore fluid pressure and episodic strain rate variations, may be considered as a small-scale example of fault behaviour associated with a cycle of interseismic creep and coseismic rupture or a new analogue for

  19. Switching deformation mode and mechanisms during subduction of continental crust: a case study from Alpine Corsica

    Science.gov (United States)

    Molli, Giancarlo; Menegon, Luca; Malasoma, Alessandro

    2017-07-01

    The switching in deformation mode (from distributed to localized) and mechanisms (viscous versus frictional) represent a relevant issue in the frame of crustal deformation, being also connected with the concept of the brittle-ductile transition and seismogenesis. In a subduction environment, switching in deformation mode and mechanisms and scale of localization may be inferred along the subduction interface, in a transition zone between the highly coupled (seismogenic zone) and decoupled deeper aseismic domain (stable slip). However, the role of brittle precursors in nucleating crystal-plastic shear zones has received more and more consideration being now recognized as fundamental in some cases for the localization of deformation and shear zone development, thus representing a case in which switching deformation mechanisms and scale and style of localization (deformation mode) interact and relate to each other. This contribution analyses an example of a millimetre-scale shear zone localized by brittle precursor formed within a host granitic protomylonite. The studied structures, developed in ambient pressure-temperature (P-T) conditions of low-grade blueschist facies (temperature T of ca. 300 °C and pressure P ≥ 0. 70 GPa) during involvement of Corsican continental crust in the Alpine subduction. We used a multidisciplinary approach by combining detailed microstructural and petrographic analyses, crystallographic preferred orientation by electron backscatter diffraction (EBSD), and palaeopiezometric studies on a selected sample to support an evolutionary model and deformation path for subducted continental crust. We infer that the studied structures, possibly formed by transient instability associated with fluctuations of pore fluid pressure and episodic strain rate variations, may be considered as a small-scale example of fault behaviour associated with a cycle of interseismic creep and coseismic rupture or a new analogue for episodic tremors and slow

  20. Irreversible magnetization process and switching mechanism in L10 FePt thin films

    Directory of Open Access Journals (Sweden)

    A. Lisfi

    2017-05-01

    Full Text Available The irreversible characteristics of the magnetization and the switching mechanism have been investigated in granular FePt films with L10 phase prepared by sputtering on a polymer substrate. The films display an extremely large magnetic anisotropy with a random distribution of the magnetization easy axis. The magnetic instabilities and the irreversible magnetization are found to be controlled by domain wall, which is responsible for the magnetization reversal. Through remanence curves and ΔM plot, the nature of magnetic interactions was revealed to be positive exchange coupling.

  1. Different threshold and bipolar resistive switching mechanisms in reactively sputtered amorphous undoped and Cr-doped vanadium oxide thin films

    Science.gov (United States)

    Rupp, Jonathan A. J.; Querré, Madec; Kindsmüller, Andreas; Besland, Marie-Paule; Janod, Etienne; Dittmann, Regina; Waser, Rainer; Wouters, Dirk J.

    2018-01-01

    This study investigates resistive switching in amorphous undoped and Cr-doped vanadium oxide thin films synthesized by sputtering deposition at low oxygen partial pressure. Two different volatile threshold switching characteristics can occur as well as a non-volatile bipolar switching mechanism, depending on device stack symmetry and Cr-doping. The two threshold switching types are associated with different crystalline phases in the conduction filament created during an initial forming step. The first kind of threshold switching, observed for undoped vanadium oxide films, was, by its temperature dependence, proven to be associated with a thermally triggered insulator-to-metal transition in a crystalline VO2 phase, whereas the threshold switch observed in chromium doped films is stable up to 90 °C and shows characteristics of an electronically induced Mott transition. This different behaviour for undoped versus doped films has been attributed to an increased stability of V3+ due to the Cr3+ doping (as evidenced by X-ray photoelectron spectroscopy analysis), probably favouring the creation of a crystalline Cr-doped V2O3 phase (rather than a Cr-doped VO2 phase) during the energetic forming step. The symmetric Pt/a-(VCr)Ox/Pt device showing high temperature stable threshold switching may find interesting applications as a possible new selector device for resistive switching memory (ReRAM) crossbar arrays.

  2. Molecular mechanism of 7TM receptor activation--a global toggle switch model

    DEFF Research Database (Denmark)

    Schwartz, Thue W; Frimurer, Thomas M; Holst, Birgitte

    2006-01-01

    active conformation, where the extracellular segments of TM-VI and -VII are bent inward toward TM-III, by acting as molecular glue deep in the main ligand-binding pocket between the helices, whereas larger agonists, peptides, and proteins can stabilize a similar active conformation by acting as Velcro......The multitude of chemically highly different agonists for 7TM receptors apparently do not share a common binding mode or active site but nevertheless act through induction of a common molecular activation mechanism. A global toggle switch model is proposed for this activation mechanism to reconcile...... the accumulated biophysical data supporting an outward rigid-body movement of the intracellular segments, as well as the recent data derived from activating metal ion sites and tethered ligands, which suggests an opposite, inward movement of the extracellular segments of the transmembrane helices. According...

  3. 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.

  4. Phenylazopyridine as Switch in Photochemical Reactions. A Detailed Computational Description of the Mechanism of Its Photoisomerization

    Directory of Open Access Journals (Sweden)

    Josep Casellas

    2017-11-01

    Full Text Available Azo compounds are organic photochromic systems that have the possibility of switching between cis and trans isomers under irradiation. The different photochemical properties of these isomers make azo compounds into good light-triggered switches, and their significantly different geometries make them very interesting as components in molecular engines or mechanical switches. For instance, azo ligands are used in coordination complexes to trigger photoresponsive properties. The light-induced trans-to-cis isomerization of phenylazopyridine (PAPy plays a fundamental role in the room-temperature switchable spin crossover of Ni-porphyrin derivatives. In this work, we present a computational study developed at the SA-CASSCF/CASPT2 level (State Averaged Complete Active Space Self Consistent Field/CAS second order Perturbation Theory to elucidate the mechanism, up to now unknown, of the cis–trans photoisomerization of 3-PAPy. We have analyzed the possible reaction pathways along its lowest excited states, generated by excitation of one or two electrons from the lone pairs of the N atoms of the azo group (nazoπ*2 and nazo2π*2 states, from a π delocalized molecular orbital (ππ* state, or from the lone pair of the N atom of the pyridine moiety (npyπ* state. Our results show that the mechanism proceeds mainly along the rotation coordinate in both the nazoπ* and ππ* excited states, although the nazo2π*2 state can also be populated temporarily, while the npyπ* does not intervene in the reaction. For rotationally constrained systems, accessible paths to reach the cis minimum along planar geometries have also been located, again on the nazoπ* and ππ* potential energy surfaces, while the nazo2π*2 and npyπ* states are not involved in the reaction. The relative energies of the different paths differ from those found for azobenzene in a previous work, so our results predict some differences between the reactivities of both compounds.

  5. Epitope Switching as a Novel Escape Mechanism of HIV to CCR5 Monoclonal Antibodies▿

    Science.gov (United States)

    Jekle, Andreas; Chhabra, Milloni; Lochner, Adriane; Meier, Sonja; Chow, Eugene; Brandt, Michael; Sankuratri, Surya; Cammack, Nick; Heilek, Gabrielle

    2010-01-01

    In passaging experiments, we isolated HIV strains resistant to MAb3952, a chemokine (C-C motif) receptor 5 (CCR5) monoclonal antibody (MAb) that binds to the second extracellular domain (extracellular loop 2 [ECL-2]) of CCR5. MAb3952-resistant viruses remain CCR5-tropic and are cross-resistant to a second ECL-2-specific antibody. Surprisingly, MAb3952-resistant viruses were more susceptible to RoAb13, a CCR5 antibody binding to the N terminus of CCR5. Using CCR5 receptor mutants, we show that MAb3952-resistant virus strains preferentially use the N terminus of CCR5, while the wild-type viruses preferentially use ECL-2. We propose this switch in the CCR5 binding site as a novel mechanism of HIV resistance. PMID:19995923

  6. Q-switched laser removal of tattoos: a clinical and spectroscopic investigation of the mechanism

    Science.gov (United States)

    Siomos, Konstadinos; Bailey, Raymond T.; Cruickshank, Frank R.; Murphy, Michael

    1996-01-01

    The liquid phase spectra of tatoo pigments are shown to be unreliable as a basis for mechanistic deductions. The reflectance spectra of the solids from 2000 nm to 500 nm (5000 to 20,000 cm-1) are shown to accurately assess the relative loss of laser light for different pigments and to be useful in examining these to check for similarities in the pigments. The absorbance differences between the pigments are shown to be largely irrelevant in assessing the ease of tatoo removal by laser radiation of a variety of wavelengths. A multiphoton absorption mechanism with its concomitant shock wave is proposed to be responsible for the reduction of pigment particles to small sizes which the lymph system can remove. The different behavior of blue and green tattoos, treated by Q-switched ruby and Nd:YAG lasers, is attributed to the particle aggregation size of the pigments in the tattoo.

  7. A pH-Dependent, Mechanically Interlocked Switch: Organometallic [2]Rotaxane vs. Organic [3]Rotaxane.

    Science.gov (United States)

    Altmann, Philipp J; Pöthig, Alexander

    2017-12-04

    We present the first [2]rotaxane featuring a functional organometallic host. In contrast to the known organic scaffolds, this assembly shows a high post-synthetic modifiability. The reactivity of the Ag 8 pillarplex host is fully retained, as is exemplified by the first transmetalation in a rotaxane framework to provide the respective Au 8 analogue. Additionally, a transformation under acidic conditions to give a purely organic [3]rotaxane is demonstrated which is reversible upon addition of a suitable base, rendering the assembly a pH-dependent switch. Hereby, it is shown that the mechanically interlocked nature of the system enhances the kinetic stability of the NHC host complex by a factor of >1000 and corresponds to the first observation of a stabilizing "rotaxand effect". © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Human and mouse switch-like genes share common transcriptional regulatory mechanisms for bimodality

    Directory of Open Access Journals (Sweden)

    Tozeren Aydin

    2008-12-01

    Full Text Available Abstract Background Gene expression is controlled over a wide range at the transcript level through complex interplay between DNA and regulatory proteins, resulting in profiles of gene expression that can be represented as normal, graded, and bimodal (switch-like distributions. We have previously performed genome-scale identification and annotation of genes with switch-like expression at the transcript level in mouse, using large microarray datasets for healthy tissue, in order to study the cellular pathways and regulatory mechanisms involving this class of genes. We showed that a large population of bimodal mouse genes encoding for cell membrane and extracellular matrix proteins is involved in communication pathways. This study expands on previous results by annotating human bimodal genes, investigating their correspondence to bimodality in mouse orthologs and exploring possible regulatory mechanisms that contribute to bimodality in gene expression in human and mouse. Results Fourteen percent of the human genes on the HGU133A array (1847 out of 13076 were identified as bimodal or switch-like. More than 40% were found to have bimodal mouse orthologs. KEGG pathways enriched for bimodal genes included ECM-receptor interaction, focal adhesion, and tight junction, showing strong similarity to the results obtained in mouse. Tissue-specific modes of expression of bimodal genes among brain, heart, and skeletal muscle were common between human and mouse. Promoter analysis revealed a higher than average number of transcription start sites per gene within the set of bimodal genes. Moreover, the bimodal gene set had differentially methylated histones compared to the set of the remaining genes in the genome. Conclusion The fact that bimodal genes were enriched within the cell membrane and extracellular environment make these genes as candidates for biomarkers for tissue specificity. The commonality of the important roles bimodal genes play in tissue

  9. Palladium-atom catalyzed formic acid decomposition and the switch of reaction mechanism with temperature.

    Science.gov (United States)

    He, Nan; Li, Zhen Hua

    2016-04-21

    Formic acid decomposition (FAD) reaction has been an innovative way for hydrogen energy. Noble metal catalysts, especially palladium-containing nanoparticles, supported or unsupported, perform well in this reaction. Herein, we considered the simplest model, wherein one Pd atom is used as the FAD catalyst. With high-level theoretical calculations of CCSD(T)/CBS quality, we investigated all possible FAD pathways. The results show that FAD catalyzed by one Pd atom follows a different mechanism compared with that catalyzed by surfaces or larger clusters. At the initial stage of the reaction, FAD follows a dehydration route and is quickly poisoned by CO due to the formation of very stable PdCO. PdCO then becomes the actual catalyst for FAD at temperatures approximately below 1050 K. Beyond 1050 K, there is a switch of catalyst from PdCO to Pd atom. The results also show that dehydration is always favoured over dehydrogenation on either the Pd-atom or PdCO catalyst. On the Pd-atom catalyst, neither dehydrogenation nor dehydration follows the formate mechanism. In contrast, on the PdCO catalyst, dehydrogenation follows the formate mechanism, whereas dehydration does not. We also systematically investigated the performance of 24 density functional theory methods. We found that the performance of the double hybrid mPW2PLYP functional is the best, followed by the B3LYP, B3PW91, N12SX, M11, and B2PLYP functionals.

  10. Investigation of the electroforming and resistive switching mechanisms in Fe-doped SrTiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Menke, Tobias

    2009-11-27

    To overcome the physical limits of todays memory technologies new concepts are needed. The resistive random access memory (RRAM), which bases on a nonvolatile and repeatable change of the resistance by external electrical stimuli, seems to be one promising candidate. Within the scope of this work, the model system Strontium titanate (SrTiO{sub 3}) has been investigated to get a deeper understanding of the underlying physical mechanism related to the resistance change. The electrical properties of SrTiO{sub 3} (STO) can be modulated from a band insulator to metallic conduction by a self-doping with oxygen vacancies which act as shallow donors. A local accumulation or depletion of oxygen vacancies at the vicinity of the surface will lead to a local redox process which is responsible for the resistance change. To study the influence of the interfaces on the switching properties of SrTiO{sub 3} thin films, epitaxial films of Fe-doped SrTiO{sub 3} were grown on different bottom electrodes (SrRuO{sub 3}, LaNiO{sub 3} und Nb:STO) by a ''Pulsed Laser Deposition'' technique. An atomic force microscope equipped with a conductive tip (LC-AFM) allowed studying the conductivity of the deposited films on the nanometer scale. Resistive switching of lateral structures smaller than {proportional_to}5 nm could be realized which represents the potential of this material for a further downscaling of RRAM devices. The deposition of top electrodes, made of Platinum or Titanium, allowed the electrical characterization of metal-insulator-metal (MIM) structures. An extensive investigation of pristine MIM-devices by impedance spectroscopy showed the big impact of the metal-insulator interface on the overall device resistance. Furthermore, a chemical polarization was studied by dynamical current sweeps and identified as a volatile resistance variation. Usually a forming procedure is needed to ''enable'' the resistive switching properties in MIM devices

  11. Investigation of the electroforming and resistive switching mechanisms in Fe-doped SrTiO3 thin films

    International Nuclear Information System (INIS)

    Menke, Tobias

    2009-01-01

    To overcome the physical limits of todays memory technologies new concepts are needed. The resistive random access memory (RRAM), which bases on a nonvolatile and repeatable change of the resistance by external electrical stimuli, seems to be one promising candidate. Within the scope of this work, the model system Strontium titanate (SrTiO 3 ) has been investigated to get a deeper understanding of the underlying physical mechanism related to the resistance change. The electrical properties of SrTiO 3 (STO) can be modulated from a band insulator to metallic conduction by a self-doping with oxygen vacancies which act as shallow donors. A local accumulation or depletion of oxygen vacancies at the vicinity of the surface will lead to a local redox process which is responsible for the resistance change. To study the influence of the interfaces on the switching properties of SrTiO 3 thin films, epitaxial films of Fe-doped SrTiO 3 were grown on different bottom electrodes (SrRuO 3 , LaNiO 3 und Nb:STO) by a ''Pulsed Laser Deposition'' technique. An atomic force microscope equipped with a conductive tip (LC-AFM) allowed studying the conductivity of the deposited films on the nanometer scale. Resistive switching of lateral structures smaller than ∝5 nm could be realized which represents the potential of this material for a further downscaling of RRAM devices. The deposition of top electrodes, made of Platinum or Titanium, allowed the electrical characterization of metal-insulator-metal (MIM) structures. An extensive investigation of pristine MIM-devices by impedance spectroscopy showed the big impact of the metal-insulator interface on the overall device resistance. Furthermore, a chemical polarization was studied by dynamical current sweeps and identified as a volatile resistance variation. Usually a forming procedure is needed to ''enable'' the resistive switching properties in MIM devices. The electroforming of these devices was extensively studied and could be

  12. The nanocoherer: an electrically and mechanically resettable resistive switching device based on gold clusters assembled on paper

    Science.gov (United States)

    Minnai, Chloé; Mirigliano, Matteo; Brown, Simon A.; Milani, Paolo

    2018-03-01

    We report the realization of a resettable resistive switching device based on a nanostructured film fabricated by supersonic cluster beam deposition of gold clusters on plain paper substrates. Through the application of suitable voltage ramps, we obtain, in the same device, either a complex pattern of resistive switchings, or reproducible and stable switchings between low resistance and high resistance states, with an amplitude up to five orders of magnitude. Our device retains a state of internal resistance following the history of the applied voltage similar to that reported for memristors. The two different switching regimes in the same device are both stable, the transition between them is reversible, and it can be controlled by applying voltage ramps or by mechanical deformation of the substrate. The device behavior can be related to the formation, growth and breaking of junctions between the loosely aggregated gold clusters forming the nanostructured films. The fact that our cluster-assembled device is mechanically resettable suggests that it can be considered as the analog of the coherer: a switching device based on metallic powders used for the first radio communication system.

  13. 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

  14. Structures of the NLRP14 pyrin domain reveal a conformational switch mechanism regulating its molecular interactions

    Energy Technology Data Exchange (ETDEWEB)

    Eibl, Clarissa; Hessenberger, Manuel; Wenger, Julia; Brandstetter, Hans, E-mail: hans.brandstetter@sbg.ac.at [University of Salzburg, Billrothstrasse 11, 5020 Salzburg (Austria)

    2014-07-01

    Pyrin domains (PYDs) recruit downstream effector molecules in NLR signalling. A specific charge-relay system suggests a the formation of a signalling complex involving a PYD dimer. The cytosolic tripartite NLR receptors serve as important signalling platforms in innate immunity. While the C-terminal domains act as sensor and activation modules, the N-terminal death-like domain, e.g. the CARD or pyrin domain, is thought to recruit downstream effector molecules by homotypic interactions. Such homotypic complexes have been determined for all members of the death-domain superfamily except for pyrin domains. Here, crystal structures of human NLRP14 pyrin-domain variants are reported. The wild-type protein as well as the clinical D86V mutant reveal an unexpected rearrangement of the C-terminal helix α6, resulting in an extended α5/6 stem-helix. This reordering mediates a novel symmetric pyrin-domain dimerization mode. The conformational switching is controlled by a charge-relay system with a drastic impact on protein stability. How the identified charge relay allows classification of NLRP receptors with respect to distinct recruitment mechanisms is discussed.

  15. Free microparticles—An inducing mechanism of pre-firing in high pressure gas switches for fast linear transformer drivers

    Science.gov (United States)

    Li, Xiaoang; Pei, Zhehao; Wu, Zhicheng; Zhang, Yuzhao; Liu, Xuandong; Li, Yongdong; Zhang, Qiaogen

    2018-03-01

    Microparticle initiated pre-firing of high pressure gas switches for fast linear transformer drivers (FLTDs) is experimentally and theoretically verified. First, a dual-electrode gas switch equipped with poly-methyl methacrylate baffles is used to capture and collect the microparticles. By analyzing the electrode surfaces and the collecting baffles by a laser scanning confocal microscope, microparticles ranging in size from tens of micrometers to over 100 μm are observed under the typical working conditions of FLTDs. The charging and movement of free microparticles in switch cavity are studied, and the strong DC electric field drives the microparticles to bounce off the electrode. Three different modes of free microparticle motion appear to be responsible for switch pre-firing. (i) Microparticles adhere to the electrode surface and act as a fixed protrusion which distorts the local electric field and initiates the breakdown in the gap. (ii) One particle escapes toward the opposite electrode and causes a near-electrode microdischarge, inducing the breakdown of the residual gap. (iii) Multiple moving microparticles are occasionally in cascade, leading to pre-firing. Finally, as experimental verification, repetitive discharges at ±90 kV are conducted in a three-electrode field-distortion gas switch, with two 8 mm gaps and pressurized with nitrogen. An ultrasonic probe is employed to monitor the bounce signals. In pre-firing incidents, the bounce is detected shortly before the collapse of the voltage waveform, which demonstrates that free microparticles contribute significantly to the mechanism that induces pre-firing in FLTD gas switches.

  16. WRN loss induces switching of telomerase-independent mechanisms of telomere elongation.

    Directory of Open Access Journals (Sweden)

    April Renee Sandy Gocha

    Full Text Available Telomere maintenance can occur in the presence of telomerase or in its absence, termed alternative lengthening of telomeres (ALT. ALT adds telomere repeats using recombination-based processes and DNA repair proteins that function in homologous recombination. Our previous work reported that the RecQ-like BLM helicase is required for ALT and that it unwinds telomeric substrates in vitro. WRN is also a RecQ-like helicase that shares many biochemical functions with BLM. WRN interacts with BLM, unwinds telomeric substrates, and co-localizes to ALT-associated PML bodies (APBs, suggesting that it may also be required for ALT processes. Using long-term siRNA knockdown of WRN in three ALT cell lines, we show that some, but not all, cell lines require WRN for telomere maintenance. VA-13 cells require WRN to prevent telomere loss and for the formation of APBs; Saos-2 cells do not. A third ALT cell line, U-2 OS, requires WRN for APB formation, however WRN loss results in p53-mediated apoptosis. In the absence of WRN and p53, U-2 OS cells undergo telomere loss for an intermediate number of population doublings (50-70, at which point they maintain telomere length even with the continued loss of WRN. WRN and the tumor suppressor BRCA1 co-localize to APBs in VA-13 and U-2 OS, but not in Saos-2 cells. WRN loss in U-2 OS is associated with a loss of BRCA1 from APBs. While the loss of WRN significantly increases telomere sister chromatid exchanges (T-SCE in these three ALT cell lines, loss of both BRCA1 and WRN does not significantly alter T-SCE. This work demonstrates that ALT cell lines use different telomerase-independent maintenance mechanisms that variably require the WRN helicase and that some cells can switch from one mechanism to another that permits telomere elongation in the absence of WRN. Our data suggest that BRCA1 localization may define these mechanisms.

  17. Reversal mechanisms and interactions in magnetic systems: coercivity versus switching field and thermally assisted demagnetization

    Directory of Open Access Journals (Sweden)

    Cebollada, F.

    2005-06-01

    Full Text Available In this paper we present a comparative analysis of the magnetic interactions and reversal mechanisms of two different systems: NdFeB-type alloys with grain sizes in the single domain range and Fe-SiO2 nanocomposites with Fe concentrations above and below the percolation threshold. We evidence that the use of the coercivity as the main parameter to analyse them might be misleading due to the convolution of both reversible and irreversible magnetization variations. We show that the switching field and thermally assisted demagnetization allow a better understanding of these mechanisms since they involve just irreversible magnetization changes. Specifically, the experimental analysis of the coercivity adquisition process for the NdFeB-type system suggests that the magnetization reversal is nucleated at the spin misalignments present due to intergranular exchange interactions. On the other hand, the study of the magnetic viscosity and of the isothermal remanent magnetization (IRM and direct field demagnetization (DCD remanence curves indicates that the dipolar interactions are responsible for the propagation of the switching started at individual particles.

    En este artículo presentamos un análisis comparativo de la influencia de la microestructura a través de las interacciones magnéticas en los mecanismos de inversión de la magnetización en dos sistemas diferentes: aleaciones tipo NdFeB con tamaños de grano en el rango de monodominio y nanocompuestos de Fe-SiO2 con concentraciones de Fe tanto por encima como por debajo del umbral de percolación. Ponemos de manifiesto que el uso del campo coercitivo como parámetro de análisis puede llevar a equívocos debido a la coexistencia de variaciones reversibles e irreversibles de la magnetización. También mostramos que el campo de conmutación y la desimanación térmicamente asistida permiten una mejor comprensión de dichos mecanismos ya que reflejan exclusivamente cambios irreversibles de

  18. Mechanical logic switches based on DNA-inspired acoustic metamaterials with ultrabroad low-frequency band gaps

    Science.gov (United States)

    Zheng, Bowen; Xu, Jun

    2017-11-01

    Mechanical information processing and control has attracted great attention in recent years. A challenging pursuit is to achieve broad functioning frequency ranges, especially at low-frequency domain. Here, we propose a design of mechanical logic switches based on DNA-inspired chiral acoustic metamaterials, which are capable of having ultrabroad band gaps at low-frequency domain. Logic operations can be easily performed by applying constraints at different locations and the functioning frequency ranges are able to be low, broad and tunable. This work may have an impact on the development of mechanical information processing, programmable materials, stress wave manipulation, as well as the isolation of noise and harmful vibration.

  19. First principles investigation of the unipolar resistive switching mechanism in an interfacial phase change memory based on a GeTe/Sb2Te3 superlattice

    Science.gov (United States)

    Shirakawa, Hiroki; Araidai, Masaaki; Shiraishi, Kenji

    2018-04-01

    The interfacial phase change memory (iPCM) based on a GeTe/Sb2Te3 superlattice is one of the candidates for future storage class memories. However, the atomic structures of the high and low resistance states (HRS/LRS) remain unclear and the resistive switching mechanism is still under debate. Clarifying the switching mechanism is essential for developing further high-reliability and low-power-consumption iPCM. We propose, on the basis of the results of first-principles molecular dynamics simulations, a mechanism for resistive switching, and describe the atomic structures of the high and low resistance states of iPCM for unipolar switching. Our simulations indicated that switching from HRS to LRS occurs with Joule heating only, while that from LRS to HRS occurs with both hole injection and Joule heating.

  20. Mathematical modeling of atopic dermatitis reveals "double-switch" mechanisms underlying 4 common disease phenotypes.

    Science.gov (United States)

    Domínguez-Hüttinger, Elisa; Christodoulides, Panayiotis; Miyauchi, Kosuke; Irvine, Alan D; Okada-Hatakeyama, Mariko; Kubo, Masato; Tanaka, Reiko J

    2017-06-01

    The skin barrier acts as the first line of defense against constant exposure to biological, microbial, physical, and chemical environmental stressors. Dynamic interplay between defects in the skin barrier, dysfunctional immune responses, and environmental stressors are major factors in the development of atopic dermatitis (AD). A systems biology modeling approach can yield significant insights into these complex and dynamic processes through integration of prior biological data. We sought to develop a multiscale mathematical model of AD pathogenesis that describes the dynamic interplay between the skin barrier, environmental stress, and immune dysregulation and use it to achieve a coherent mechanistic understanding of the onset, progression, and prevention of AD. We mathematically investigated synergistic effects of known genetic and environmental risk factors on the dynamic onset and progression of the AD phenotype, from a mostly asymptomatic mild phenotype to a severe treatment-resistant form. Our model analysis identified a "double switch," with 2 concatenated bistable switches, as a key network motif that dictates AD pathogenesis: the first switch is responsible for the reversible onset of inflammation, and the second switch is triggered by long-lasting or frequent activation of the first switch, causing irreversible onset of systemic T H 2 sensitization and worsening of AD symptoms. Our mathematical analysis of the bistable switch predicts that genetic risk factors decrease the threshold of environmental stressors to trigger systemic T H 2 sensitization. This analysis predicts and explains 4 common clinical AD phenotypes from a mild and reversible phenotype through to severe and recalcitrant disease and provides a mechanistic explanation for clinically demonstrated preventive effects of emollient treatments against development of AD. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  1. Discussions on switching mechanism for ultimate reduction in energy consumption for STT-MRAM

    Science.gov (United States)

    Yoda, H.; Shimomura, N.

    2016-10-01

    Critical switching current, ICsw, of STT (Spin Transfer Torque)-MRAM has been reduced by several orders with PMA (Perpendicular Magnetic Anisotropy)-MTJs and the state-of-the-art writing-charge, Qw, becomes the order of 100fC. With the small Qw, MRAM starts to save energy consumption even for mobile applications. The key to the Qw reduction is a development of MTJs having higher writing-efficiency. Especially coherent switching of storage-layer magnetization was found to be the root key to the high efficiency.

  2. Nonvolatile data storage using mechanical force-induced polarization switching in ferroelectric polymer

    International Nuclear Information System (INIS)

    Chen, Xin; Tang, Xin; Chen, Xiang-Zhong; Chen, Yu-Lei; Shen, Qun-Dong; Guo, Xu; Ge, Hai-Xiong

    2015-01-01

    Ferroelectric polymers offer the promise of low-cost and flexible electronic products. They are attractive for information storage due to their spontaneous polarization which is usually switched by electric field. Here, we demonstrate that electrical signals can be readily written on ultra-thin ferroelectric polymer films by strain gradient-induced polarization switching (flexoelectric effect). A force with magnitude as small as 64nN is enough to induce highly localized (40 nm feature size) change in the polarization states. The methodology is capable of realizing nonvolatile memory devices with miniaturized cell size and storage density of tens to hundreds Gbit per square inch

  3. Phenotype switching : tumor cell plasticity as a resistance mechanism and target for therapy

    NARCIS (Netherlands)

    Kemper, K.; de Goeje, P.L.; Peeper, D.S.; van Amerongen, R.

    2014-01-01

    Mutations in BRAF are present in the majority of patients with melanoma, rendering these tumors sensitive to targeted therapy with BRAF and MEK inhibitors. Unfortunately, resistance almost invariably develops. Recently, a phenomenon called "phenotype switching" has been identified as an escape

  4. Flexible switching of feedback control mechanisms allows for learning of different task dynamics.

    Science.gov (United States)

    White, Olivier; Diedrichsen, Jörn

    2013-01-01

    To produce skilled movements, the brain flexibly adapts to different task requirements and movement contexts. Two core abilities underlie this flexibility. First, depending on the task, the motor system must rapidly switch the way it produces motor commands and how it corrects movements online, i.e. it switches between different (feedback) control policies. Second, it must also adapt to environmental changes for different tasks separately. Here we show these two abilities are related. In a bimanual movement task, we show that participants can switch on a movement-by-movement basis between two feedback control policies, depending only on a static visual cue. When this cue indicates that the hands control separate objects, reactions to force field perturbations of each arm are purely unilateral. In contrast, when the visual cue indicates a commonly controlled object, reactions are shared across hands. Participants are also able to learn different force fields associated with a visual cue. This is however only the case when the visual cue is associated with different feedback control policies. These results indicate that when the motor system can flexibly switch between different control policies, it is also able to adapt separately to the dynamics of different environmental contexts. In contrast, visual cues that are not associated with different control policies are not effective for learning different task dynamics.

  5. Mechanisms of charge transport and resistive switching in composite films of semiconducting polymers with nanoparticles of graphene and graphene oxide

    Science.gov (United States)

    Berestennikov, A. S.; Aleshin, A. N.

    2017-11-01

    We have investigated the effect of the resistive switching in the composite films based on polyfunctional polymers - PVK, PFD and PVC mixed with particles of Gr and GO with the concentration of ˜ 1 - 3 wt.%. We have developed the solution processed hybrid memory structures based on PVK and GO particles composite films. The effect of the resistive switching in Al/PVK(PFD; PVC):Gr(GO)/ITO/PET structures manifests itself as a sharp change of the electrical resistance from a low-conducting state to a relatively high-conducting state when applying a bias to Al-ITO electrodes of ˜ 0.2-0.4 V. It has been established that a sharp conductivity jump characterized by S-shaped current-voltage curves and the presence of their hysteresis occurs upon applying a voltage pulse to the Au/PVK(PFD; PVC):Gr(GO)/ITO/PET structures, with the switching time in the range from 1 to 30 μs. The mechanism of resistive switching associated with the processes of capture and accumulation of charge carriers by Gr(GO) particles introduced into the matrixes of the PVK polymer due to the reduction/oxidation processes. The possible mechanisms of energy transfer between organic and inorganic components in PVK(PFD; PVC):GO(Gr) films causes increase mobility are discussed. Incorporating of Gr (GO) particles into the polymer matrix is a promising route to enhance the performance of hybrid memory structures, as well as it is an effective medium for memory cells.

  6. Breakover mechanism of GaAs photoconductive switch triggering spark gap for high power applications

    Science.gov (United States)

    Tian, Liqiang; Shi, Wei; Feng, Qingqing

    2011-11-01

    A spark gap (SG) triggered by a semi-insulating GaAs photoconductive semiconductor switch (PCSS) is presented. Currents as high as 5.6 kA have been generated using the combined switch, which is excited by a laser pulse with energy of 1.8 mJ and under a bias of 4 kV. Based on the transferred-electron effect and gas streamer theory, the breakover characteristics of the combined switch are analyzed. The photoexcited carrier density in the PCSS is calculated. The calculation and analysis indicate that the PCSS breakover is caused by nucleation of the photoactivated avalanching charge domain. It is shown that the high output current is generated by the discharge of a high-energy gas streamer induced by the strong local electric field distortion or by overvoltage of the SG resulting from quenching of the avalanching domain, and periodic oscillation of the current is caused by interaction between the gas streamer and the charge domain. The cycle of the current oscillation is determined by the rise time of the triggering electric pulse generated by the PCSS, the pulse transmission time between the PCSS and the SG, and the streamer transit time in the SG.

  7. Generation of high-voltage pulses with a subnanosecond leading edge in an open discharge. II. Switching mechanism

    Science.gov (United States)

    Bokhan, P. A.; Gugin, P. P.; Zakrevskii, D. E.; Lavrukhin, M. A.

    2015-10-01

    The mechanism of fast switching in open-discharge-based devices is clarified by analyzing the feature of the I-V characteristic of a quasi-stationary open discharge: at a voltage of 3-4 kV, the characteristic sharply rises, obeying the law j ~ U y with y > 10 ( j is the current density). Such a run of the curve is explained by the fact that at U > 3 kV helium atom excitation by fast helium atoms becomes the main reason for VUV radiation. Fast helium atoms result from the resonance charge exchange between He+ ions moving from the anode to the cathode. In the coaxial design and in the sandwich design consisting of two accelerating gaps in which electrons move toward each other, multiple oscillations of electrons take place. This favors the generation of fast atoms and, accordingly, resonance VUV photons. Switching times as short as 0.5 ns are achieved. The minimal switching time estimated from experimental data equals 100 ps.

  8. Molecular-Mechanical Switching at the Nanoparticle-Solvent Interface: Practice and Theory

    Energy Technology Data Exchange (ETDEWEB)

    Coskun, Ali; Wesson, Paul J.; Klajn, Rafal; Trabolsi, Ali; Fang, Lei; Olson, Mark A.; Dey, Sanjeev K.; Grzybowski, Bartosz A.; Stoddart, J. Fraser

    2010-03-10

    A range (Au, Pt, Pd) of metal nanoparticles (MNPs) has been prepared and functionalized with (a) redox-active stalks containing tetrathiafulvalene (TTF) units, (b) [2]pseudorotaxanes formed between these stalks and cyclobis(paraquat-p-phenylene) (CBPQT4+) rings, and (c) bistable [2]rotaxane molecules where the dumbbell component contains a 1,5-dioxynaphthalene (DNP) unit, as well as a TTF unit, encircled by a CBPQT4+ ring. It transpires that the molecules present in (a) and (c) and the supermolecules described in (b) retain their switching characteristics, previously observed in solution, when they are immobilized onto MNPs. Moreover, their oxidation potentials depend on the fraction, χ, of the molecules or supermolecules on the surface of the nanoparticles. A variation in χ affects the oxidation potentials of the TTF units to the extent that switching can be subjected to fine tuning as a result. Specifically, increasing χ results in positive shifts (i) in the oxidation potentials of the TTF unit in (a)-(c) and (ii) the reduction potentials of the CBPQT4+ rings in (c). These shifts can be attributed to an increase in the electrostatic potential surrounding the MNPs. Both the magnitude and the direction of these shifts are reproduced by a model, based on the Poisson-Boltzmann equation coupled with charge-regulating boundary conditions. Furthermore, the kinetics of relaxation from the metastable state coconformation (MSCC) to the ground-state coconformation (GSCC) of the bistable [2]rotaxane molecules also depends on χ, as well as on the nanoparticle diameter. Increasing either of these parameters accelerates the rate of relaxation from the MSCC to the GSCC. This rate is a function of (i) the activation energy for the relaxation process associated with the bistable [2]rotaxane molecules in solution and (ii) the electrostatic potential surrounding the MNPs. The electrostatic potential depends on (i) the diameter of the MNPs, (ii) the amount

  9. Molecular-Mechanical Switching at the Nanoparticle-Solvent Interface: Practice and Theory

    Energy Technology Data Exchange (ETDEWEB)

    Coskun, Ali [Northwestern Univ., Evanston, IL (United States); Wesson, Paul J. [Northwestern Univ., Evanston, IL (United States); Klajn, Rafal [Northwestern Univ., Evanston, IL (United States); Trabolsi, Ali [Northwestern Univ., Evanston, IL (United States); Fang, Lei [Northwestern Univ., Evanston, IL (United States); Olson, Mark A. [Northwestern Univ., Evanston, IL (United States); Dey, Sanjeev K. [Northwestern Univ., Evanston, IL (United States); Grzybowski, Bartosz A. [Northwestern Univ., Evanston, IL (United States); Stoddart, J. Fraser [Northwestern Univ., Evanston, IL (United States)

    2010-01-01

    A range (Au, Pt, Pd) of metal nanoparticles (MNPs) has been prepared and functionalized with (a) redox-active stalks containing tetrathiafulvalene (TTF) units, (b) [2]pseudorotaxanes formed between these stalks and cyclobis(paraquat-p-phenylene) (CBPQT4+) rings, and (c) bistable [2]rotaxane molecules where the dumbbell component contains a 1,5-dioxynaphthalene (DNP) unit, as well as a TTF unit, encircled by a CBPQT4+ ring. It transpires that the molecules present in (a) and (c) and the supermolecules described in (b) retain their switching characteristics, previously observed in solution, when they are immobilized onto MNPs. Moreover, their oxidation potentials depend on the fraction, χ, of the molecules or supermolecules on the surface of the nanoparticles. A variation in χ affects the oxidation potentials of the TTF units to the extent that switching can be subjected to fine tuning as a result. Specifically, increasing χ results in positive shifts (i) in the oxidation potentials of the TTF unit in (a)-(c) and (ii) the reduction potentials of the CBPQT4+ rings in (c). These shifts can be attributed to an increase in the electrostatic potential surrounding the MNPs. Both the magnitude and the direction of these shifts are reproduced by a model, based on the Poisson-Boltzmann equation coupled with charge-regulating boundary conditions. Furthermore, the kinetics of relaxation from the metastable state coconformation (MSCC) to the ground-state coconformation (GSCC) of the bistable [2]rotaxane molecules also depends on χ, as well as on the nanoparticle diameter. Increasing either of these parameters accelerates the rate of relaxation from the MSCC to the GSCC. This rate is a function of (i) the activation energy for the relaxation process associated with the bistable [2]rotaxane molecules in solution and (ii) the electrostatic potential surrounding the MNPs. The electrostatic potential depends on (i) the diameter of the MNPs, (ii

  10. Direct observation of a force-induced switch in the anisotropic mechanical unfolding pathway of a protein.

    Science.gov (United States)

    Jagannathan, Bharat; Elms, Phillip J; Bustamante, Carlos; Marqusee, Susan

    2012-10-30

    Many biological processes generate force, and proteins have evolved to resist and respond to tension along different force axes. Single-molecule force spectroscopy allows for molecular insight into the behavior of proteins under force and the mechanism of protein folding in general. Here, we have used src SH3 to investigate the effect of different pulling axes under the low-force regime afforded by an optical trap. We find that this small cooperatively folded protein shows an anisotropic response to force; the protein is more mechanically resistant to force applied along a longitudinal axis compared to force applied perpendicular to the terminal β strand. In the longitudinal axis, we observe an unusual biphasic behavior revealing a force-induced switch in the unfolding mechanism suggesting the existence of two parallel unfolding pathways. A site-specific variant can selectively affect one of these pathways. Thus, even this simple two-state protein demonstrates a complex mechanical unfolding trajectory, accessing multiple unfolding pathways under the low-force regime of the optical trap; the specific unfolding pathway depends on the perturbation axis and the applied force.

  11. Electric and Mechanical Switching of Ferroelectric and Resistive States in Semiconducting BaTiO3-δ Films on Silicon.

    Science.gov (United States)

    Gómez, Andrés; Vila-Fungueiriño, José Manuel; Moalla, Rahma; Saint-Girons, Guillaume; Gázquez, Jaume; Varela, María; Bachelet, Romain; Gich, Martí; Rivadulla, Francisco; Carretero-Genevrier, Adrián

    2017-10-01

    Materials that can couple electrical and mechanical properties constitute a key element of smart actuators, energy harvesters, or many sensing devices. Within this class, functional oxides display specific mesoscale responses which often result in great sensitivity to small external stimuli. Here, a novel combination of molecular beam epitaxy and a water-based chemical-solution method is used for the design of mechanically controlled multilevel device integrated on silicon. In particular, the possibility of adding extra functionalities to a ferroelectric oxide heterostructure by n-doping and nanostructuring a BaTiO 3 thin film on Si(001) is explored. It is found that the ferroelectric polarization can be reversed, and resistive switching can be measured, upon a mechanical load in epitaxial BaTiO 3- δ /La 0.7 Sr 0.3 MnO 3 /SrTiO 3 /Si columnar nanostructures. A flexoelectric effect is found, stemming from substantial strain gradients that can be created with moderate loads. Simultaneously, mechanical effects on the local conductivity can be used to modulate a nonvolatile resistive state of the BaTiO 3- δ heterostructure. As a result, three different configurations of the system become accessible on top of the usual voltage reversal of polarization and resistive states. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Novel failure mechanism and improvement for split-gate trench MOSFET with large current under unclamped inductive switch stress

    Science.gov (United States)

    Tian, Ye; Yang, Zhuo; Xu, Zhiyuan; Liu, Siyang; Sun, Weifeng; Shi, Longxing; Zhu, Yuanzheng; Ye, Peng; Zhou, Jincheng

    2018-04-01

    In this paper, a novel failure mechanism under unclamped inductive switch (UIS) for Split-Gate Trench Metal Oxide Semiconductor Field Effect Transistor (MOSFET) with large current is investigated. The device sample is tested and analyzed in detail. The simulation results demonstrate that the nonuniform potential distribution of the source poly should be responsible for the failure. Three structures are proposed and verified available to improve the device UIS ruggedness by TCAD simulation. The best one of the structures the device with source metal inserting into source poly through contacts in the field oxide is carried out and measured. The results demonstrate that the optimized structure can balance the trade-off between the UIS ruggedness and the static characteristics.

  13. Vestigialization of an Allosteric Switch: Genetic and Structural Mechanisms for the Evolution of Constitutive Activity in a Steroid Hormone Receptor

    Science.gov (United States)

    Bridgham, Jamie T.; Keay, June; Ortlund, Eric A.; Thornton, Joseph W.

    2014-01-01

    An important goal in molecular evolution is to understand the genetic and physical mechanisms by which protein functions evolve and, in turn, to characterize how a protein's physical architecture influences its evolution. Here we dissect the mechanisms for an evolutionary shift in function in the mollusk ortholog of the steroid hormone receptors (SRs), a family of biologically essential transcription factors. In vertebrates, the activity of SRs allosterically depends on binding a hormonal ligand; in mollusks, however, the SR ortholog (called ER, because of high sequence similarity to vertebrate estrogen receptors) activates transcription in the absence of ligand and does not respond to steroid hormones. To understand how this shift in regulation evolved, we combined evolutionary, structural, and functional analyses. We first determined the X-ray crystal structure of the ER of the Pacific oyster Crassostrea gigas (CgER), and found that its ligand pocket is filled with bulky residues that prevent ligand occupancy. To understand the genetic basis for the evolution of mollusk ERs' unique functions, we resurrected an ancient SR progenitor and characterized the effect of historical amino acid replacements on its functions. We found that reintroducing just two ancient replacements from the lineage leading to mollusk ERs recapitulates the evolution of full constitutive activity and the loss of ligand activation. These substitutions stabilize interactions among key helices, causing the allosteric switch to become “stuck” in the active conformation and making activation independent of ligand binding. Subsequent changes filled the ligand pocket without further affecting activity; by degrading the allosteric switch, these substitutions vestigialized elements of the protein's architecture required for ligand regulation and made reversal to the ancestral function more complex. These findings show how the physical architecture of allostery enabled a few large-effect mutations

  14. A novel mechanism for switching a neural system from one state to another

    Directory of Open Access Journals (Sweden)

    Chethan Pandarinath

    2010-03-01

    Full Text Available An animal’s ability to rapidly adjust to new conditions is essential to its survival. The nervous system, then, must be built with the flexibility to adjust, or shift, its processing capabilities on the fly. To understand how this flexibility comes about, we tracked a well-known behavioral shift, a visual integration shift, down to its underlying circuitry, and found that it is produced by a novel mechanism – a change in gap junction coupling that can turn a cell class on and off. The results showed that the turning on and off of a cell class shifted the circuit’s behavior from one state to another, and, likewise, the animal’s behavior. The widespread presence of similar gap junction-coupled networks in the brain suggests that this mechanism may underlie other behavioral shifts as well.

  15. Mechanical strain can switch the sign of quantum capacitance from positive to negative.

    Science.gov (United States)

    Hanlumyuang, Yuranan; Li, Xiaobao; Sharma, Pradeep

    2014-11-14

    Quantum capacitance is a fundamental quantity that can directly reveal many-body interactions among electrons and is expected to play a critical role in nanoelectronics. One of the many tantalizing recent physical revelations about quantum capacitance is that it can possess a negative value, hence allowing for the possibility of enhancing the overall capacitance in some particular material systems beyond the scaling predicted by classical electrostatics. Using detailed quantum mechanical simulations, we found an intriguing result that mechanical strains can tune both signs and values of quantum capacitance. We used a small coaxially gated carbon nanotube as a paradigmatical capacitor system and showed that, for the range of mechanical strain considered, quantum capacitance can be adjusted from very large positive to very large negative values (in the order of plus/minus hundreds of attofarads), compared to the corresponding classical geometric value (0.31035 aF). This finding opens novel avenues in designing quantum capacitance for applications in nanosensors, energy storage, and nanoelectronics.

  16. A palmitoylation switch mechanism regulates Rac1 function and membrane organization

    Science.gov (United States)

    Navarro-Lérida, Inmaculada; Sánchez-Perales, Sara; Calvo, María; Rentero, Carles; Zheng, Yi; Enrich, Carlos; Del Pozo, Miguel A

    2012-01-01

    The small GTPase Rac1 plays important roles in many processes, including cytoskeletal reorganization, cell migration, cell-cycle progression and gene expression. The initiation of Rac1 signalling requires at least two mechanisms: GTP loading via the guanosine triphosphate (GTP)/guanosine diphosphate (GDP) cycle, and targeting to cholesterol-rich liquid-ordered plasma membrane microdomains. Little is known about the molecular mechanisms governing this specific compartmentalization. We show that Rac1 can incorporate palmitate at cysteine 178 and that this post-translational modification targets Rac1 for stabilization at actin cytoskeleton-linked ordered membrane regions. Palmitoylation of Rac1 requires its prior prenylation and the intact C-terminal polybasic region and is regulated by the triproline-rich motif. Non-palmitoylated Rac1 shows decreased GTP loading and lower association with detergent-resistant (liquid-ordered) membranes (DRMs). Cells expressing no Rac1 or a palmitoylation-deficient mutant have an increased content of disordered membrane domains, and markers of ordered membranes isolated from Rac1-deficient cells do not correctly partition in DRMs. Importantly, cells lacking Rac1 palmitoylation show spreading and migration defects. These data identify palmitoylation as a mechanism for Rac1 function in actin cytoskeleton remodelling by controlling its membrane partitioning, which in turn regulates membrane organization. PMID:22157745

  17. Dual-functional Memory and Threshold Resistive Switching Based on the Push-Pull Mechanism of Oxygen Ions

    KAUST Repository

    Huang, Yi-Jen

    2016-04-07

    The combination of nonvolatile memory switching and volatile threshold switching functions of transition metal oxides in crossbar memory arrays is of great potential for replacing charge-based flash memory in very-large-scale integration. Here, we show that the resistive switching material structure, (amorphous TiOx)/(Ag nanoparticles)/(polycrystalline TiOx), fabricated on the textured-FTO substrate with ITO as the top electrode exhibits both the memory switching and threshold switching functions. When the device is used for resistive switching, it is forming-free for resistive memory applications with low operation voltage (<±1 V) and self-compliance to current up to 50 μA. When it is used for threshold switching, the low threshold current is beneficial for improving the device selectivity. The variation of oxygen distribution measured by energy dispersive X-ray spectroscopy and scanning transmission electron microscopy indicates the formation or rupture of conducting filaments in the device at different resistance states. It is therefore suggested that the push and pull actions of oxygen ions in the amorphous TiOx and polycrystalline TiOx films during the voltage sweep account for the memory switching and threshold switching properties in the device.

  18. Switching of both local ferroelectric and magnetic domains in multiferroic Bi0.9La0.1FeO3 thin film by mechanical force.

    Science.gov (United States)

    Jia, Tingting; Kimura, Hideo; Cheng, Zhenxiang; Zhao, Hongyang

    2016-08-22

    Cross-coupling of ordering parameters in multiferroic materials by multiple external stimuli other than electric field and magnetic field is highly desirable from both practical application and fundamental study points of view. Recently, mechanical force has attracted great attention in switching of ferroic ordering parameters via electro-elastic coupling in ferroelectric materials. In this work, mechanical force induced both polarization and magnetization switching were visualized in a polycrystalline multiferroic Bi0.9La0.1FeO3 thin film using a scanning probe microscopy system. The piezoresponse force microscopy and magnetic force microscopy responses suggest that both the ferroelectric domains and the magnetic domains in Bi0.9La0.1FeO3 film could be switched by mechanical force as well as by electric field. High tip stress applied on our thin film is demonstrated as able to induce ferroelastic switching and thus induce both ferroelectric dipole and magnetic spin flipping, as a consequence of electro-elastic coupling and magneto-electric coupling. The demonstration of mechanical force control of both the ferroelectric and the magnetic domains at room temperature provides a new freedom for manipulation of multiferroics and could result in devices with novel functionalities.

  19. Evaluation of QoS differentiation mechanisms in asynchronous bufferless optical packet-switched networks

    DEFF Research Database (Denmark)

    Overby, H.; Stol, N.; Nord, Martin

    2006-01-01

    Existing quality of service differentiation schemes for today's IP over point-to-point optical WDM networks take advantage of electronic RAM to implement traffic management algorithms in order to isolate the service classes. Since practical optical RAM is not available, these techniques...... the performance of the presented schemes and qualitatively discuss implementation issues, in order to evaluate the mechanisms. In particular, we present an evaluation framework, which quantifies the throughput reduction observed when migrating from a best effort scenario to a service-differentiated scenario. Our...... study shows that preemption-based schemes have the best performance, but also the highest implementation complexity....

  20. The mechanism of switching from an acidogenic to butanol-acetone fermentation by Clostridium acetobutylicum

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, P.

    1992-01-01

    The overall objective of this project is to elucidate the detailed mechanism by which solvent-forming bacteria such as Clostridium acetobutylicum regulate the well-known shift in fermentation pathway between alcohol-acetone and organic acid production. It is desired to eventually isolate and describe: (1) the regulatory genes and protein elements that determine induction of synthesis of the solvent-pathway enzymes; and (2) how this regulation system interacts with the sporulatin induction and development program and with related pathways such as granulse and exopolysaccharide formation in clostridia. A working model forhow clostridial control systems work can be derived from recent research on stress systems in E. coli and sporulation in Bacillus subtilis.

  1. Neuro-Oscillatory Mechanisms of Intersensory Selective Attention and Task Switching in School-Aged Children, Adolescents and Young Adults

    Science.gov (United States)

    Murphy, Jeremy W.; Foxe, John J.; Molholm, Sophie

    2016-01-01

    The ability to attend to one among multiple sources of information is central to everyday functioning. Just as central is the ability to switch attention among competing inputs as the task at hand changes. Such processes develop surprisingly slowly, such that even into adolescence, we remain slower and more error prone at switching among tasks…

  2. Exploring Mechanisms of Ferroelectric Switching in Real Time Using In Situ TEM

    Science.gov (United States)

    Winkler, Christopher Reid

    The need for force feedback and spatial awareness of contact in harsh environment applications, such as space servicing, has been unsatisfied due to the inability of current sensor technology to resist environmental effects. In this work, capacitive sensors based on a porous polymer-ceramic composite structure were evaluated for potential use in future operations within robotic end-effectors, withstanding temperatures ranging from -80 °C to 120 °C and forces up to 350 kPa. A thin-film design is utilized to allow for ease of embedding, allowing sensors to be implemented into exciting robotic hardware with minimal intrusion, and protecting sensors from electron bombardment, radiation, and point concentrations from metal-on-metal contact. Furthermore, said embedding is proposed to protect against environmental effects including electron bombardment, radiation, atomic oxygen, and damage caused by point concentrations during metal-on-metal contact. The novel sensor design optimizes constituent properties to maximize the response and reduce background noise, hysteresis, and thermal and mechanical drift. Selection of continuants and design parameters is presented explicitly, including synthesis and preparation of necessary materials and execution of processing methods. Qualification of the design is achieved through thorough dynamic, quasi-static, and long term static thermomechancial loading schedules ranging from -80 to 120 ºC and 20 to 360 kPa with in-situ electrical acquisition. The final composition is also shown to meet necessary outgassing standards for in-orbit operations. Additional parameters are presented for selection of necessary substrate and electrode materials, further optimizing the applied technology. An analytical model for pressure sensors is also constructed, predicting the capacitive response of a porous, polymer-ceramic composite under an applied pressure. Consisting of mechanical and dielectric counterparts, the iterative model is constructed in

  3. Fault Tolerant Mechanism for Multimedia Flows in Wireless Ad Hoc Networks Based on Fast Switching Paths

    Directory of Open Access Journals (Sweden)

    Juan R. Diaz

    2014-01-01

    Full Text Available Multimedia traffic can be forwarded through a wireless ad hoc network using the available resources of the nodes. Several models and protocols have been designed in order to organize and arrange the nodes to improve transmissions along the network. We use a cluster-based framework, called MWAHCA architecture, which optimizes multimedia transmissions over a wireless ad hoc network. It was proposed by us in a previous research work. This architecture is focused on decreasing quality of service (QoS parameters like latency, jitter, and packet loss, but other network features were not developed, like load balance or fault tolerance. In this paper, we propose a new fault tolerance mechanism, using as a base the MWAHCA architecture, in order to recover any multimedia flow crossing the wireless ad hoc network when there is a node failure. The algorithm can run independently for each multimedia flow. The main objective is to keep the QoS parameters as low as possible. To achieve this goal, the convergence time must be controlled and reduced. This paper provides the designed protocol, the analytical model of the algorithm, and a software application developed to test its performance in a real laboratory.

  4. A fuzzy logic controller based approach to model the switching mechanism of the mammalian central carbon metabolic pathway in normal and cancer cells.

    Science.gov (United States)

    Dasgupta, Abhijit; Paul, Debjyoti; De, Rajat K

    2016-07-19

    Dynamics of large nonlinear complex systems, like metabolic networks, depend on several parameters. A metabolic pathway may switch to another pathway in accordance with the current state of parameters in both normal and cancer cells. Here, most of the parameter values are unknown to us. A fuzzy logic controller (FLC) has been developed here for the purpose of modeling metabolic networks by approximating the reasons for the behaviour of a system and applying expert knowledge to track switching between metabolic pathways. The simulation results can track the switching between glycolysis and gluconeogenesis, as well as glycolysis and pentose phosphate pathways (PPP) in normal cells. Unlike normal cells, pyruvate kinase (M2 isoform) (PKM2) switches alternatively between its two oligomeric forms, i.e. an active tetramer and a relatively low activity dimer, in cancer cells. Besides, there is a coordination among PKM2 switching and enzymes catalyzing PPP. These phenomena help cancer cells to maintain their high energy demand and macromolecular synthesis. However, the reduction of initial adenosine triphosphate (ATP) to a very low concentration, decreasing initial glucose uptake, destroying coordination between glycolysis and PPP, and replacement of PKM2 by its relatively inactive oligomeric form (dimer) or inhibition of the translation of PKM2 may destabilize the mutated control mechanism of the mammalian central carbon metabolic (CCM) pathway in cancer cells. The performance of the model is compared appropriately with some existing ones.

  5. A Coincidence Detection Mechanism Controls PX-BAR Domain-Mediated Endocytic Membrane Remodeling via an Allosteric Structural Switch.

    Science.gov (United States)

    Lo, Wen-Ting; Vujičić Žagar, Andreja; Gerth, Fabian; Lehmann, Martin; Puchkov, Dymtro; Krylova, Oxana; Freund, Christian; Scapozza, Leonardo; Vadas, Oscar; Haucke, Volker

    2017-11-20

    Clathrin-mediated endocytosis occurs by bending and remodeling of the membrane underneath the coat. Bin-amphiphysin-rvs (BAR) domain proteins are crucial for endocytic membrane remodeling, but how their activity is spatiotemporally controlled is largely unknown. We demonstrate that the membrane remodeling activity of sorting nexin 9 (SNX9), a late-acting endocytic PX-BAR domain protein required for constriction of U-shaped endocytic intermediates, is controlled by an allosteric structural switch involving coincident detection of the clathrin adaptor AP2 and phosphatidylinositol-3,4-bisphosphate (PI(3,4)P 2 ) at endocytic sites. Structural, biochemical, and cell biological data show that SNX9 is autoinhibited in solution. Binding to PI(3,4)P 2 via its PX-BAR domain, and concomitant association with AP2 via sequences in the linker region, releases SNX9 autoinhibitory contacts to enable membrane constriction. Our results reveal a mechanism for restricting the latent membrane remodeling activity of BAR domain proteins to allow spatiotemporal coupling of membrane constriction to the progression of the endocytic pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. 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.

  7. Investigation of a Co-Axial Dual-Mechanical Ports Flux-Switching Permanent Magnet Machine for Hybrid Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Wei Hua

    2015-12-01

    Full Text Available In this paper, a co-axial dual-mechanical ports flux-switching permanent magnet (CADMP-FSPM machine for hybrid electric vehicles (HEVs is proposed and investigated, which is comprised of two conventional co-axial FSPM machines, namely one high-speed inner rotor machine and one low-speed outer rotor machine and a non-magnetic ring sandwiched in between. Firstly, the topology and operation principle of the CADMP-FSPM machine are introduced; secondly, the control system of the proposed electronically-controlled continuously-variable transmission (E-CVT system is given; thirdly, the key design specifications of the CADMP-FSPM machine are determined based on a conventional dual-mechanical ports (DMP machine with a wound inner rotor. Fourthly, the performances of the CADMP-FSPM machine and the normal DMP machine under the same overall volume are compared, and the results indicate that the CADMP-FSPM machine has advantages over the conventional DMP machine in the elimination of brushes and slip rings, improved thermal dissipation conditions for the inner rotor, direct-driven operation, more flexible modes, lower cogging torque and torque ripple, lower total harmonic distortion (THD values of phase PM flux linkage and phase electro-motive force (EMF, higher torque output capability and is suitable for the E-CVT systems. Finally, the pros and cons of the CADMP-FSPM machine are highlighted. This paper lays a theoretical foundation for further research on CADMP-FSPM machines used for HEVs.

  8. 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.

  9. 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

  10. 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.)

  11. Microstructure and mechanical changes induced by Q-Switched pulse laser on human enamel with aim of caries prevention

    Science.gov (United States)

    Apsari, R.; Pratomo, D. A.; Hikmawati, D.; Bidin, N.

    2016-03-01

    This study was conducted to determine the effect of Q-Switched Nd: YAG laser energy dose to human enamel caries. The specifications of Q-Switched Nd: YAG laser as followed: wavelength of 1064 nm and 6 ns pulse width. Caries enamel samples taken from human teeth molars of 17-35 ages and the type of media caries. Energy doses used in this study were 723.65 mJ/cm2, 767.72 mJ/cm2, and 1065.515 mJ/cm2; 5 Hz repetition rate, and 20 second exposure time. Samples characterized the surface morphology and the percentage of constituent elements, especially calcium/phosphorus (Ca/P) with FESEM-EDAX. The fraction volume and crystallinity percentage of hydroxyapatite (HA) with XRD and hardness value using Vickers Microhardness Test. The results indicated that exposure of Q-Switched Nd:YAG laser on enamel caries resulting cracks, holes, and melt due to plasma production effects in the surface. Plasma production effect also resulted in micro properties such as percentage of Ca/P was close to normal, the fraction volume and crystallinity percentage of HA went up but did not change the crystal structure (in terms of the lattice structure). The hardness value also rose as linear as exposure energy dose caused by phototermal effect. Based on the results, Q-Switched Nd:YAG laser can be used as contactless drill dental caries replacement candidate with the additional therapy effect such as localized caries in order to avoid the spread, the ratio of Ca/P approaching healthy teeth, the fraction volume and crystallinity percentage of HA rose and established stronger teeth with peak energy dose 1065.515 mJ/cm2.

  12. 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.

  13. 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

  14. Holding current and switch-on mechanisms in 12 kV, 100 A 4H-SiC optically triggered thyristors

    International Nuclear Information System (INIS)

    Levinshtein, M E; Rumyantsev, S L; Shur, M S; Mnatsakanov, T T; Yurkov, S N; Zhang, Q J; Agarwal, A K; Cheng, L; Palmour, J W

    2013-01-01

    Temperature dependence of the holding current has been studied in high-voltage (12 kV class) 4H-SiC optically triggered thyristors in the temperature range from 300 to 425 K. The holding current I h monotonically decreases with increasing temperature T due to two factors: enhanced thermal ionization of comparatively deep Al acceptors in the p + emitter and increasing carrier lifetime in the blocking p base. The I h (T) dependence reveals the existence of a ‘weak point’ within the optical window, which is characterized by a substantially smaller critical charge than that within the remaining part of the window. Analysis of the I h (T) dependence confirms that high-voltage SiC thyristors are switched-on at room temperature only at a high injection level in the blocking base. At elevated temperatures, the same thyristor is switched on by the ‘classical’ mechanism typical of Si thyristors. Effective shunting of the p ++ –n emitter junction affects the properties of the thyristor. Possible effective-shunting mechanisms are discussed. (paper)

  15. Using post-breakdown conduction study in a MIS structure to better understand the resistive switching mechanism in an MIM stack

    International Nuclear Information System (INIS)

    Wu Xing; Pey, Kin-Leong; Raghavan, Nagarajan; Liu, Wen-Hu; Li Xiang; Bai Ping; Zhang Gang; Bosman, Michel

    2011-01-01

    We apply our understanding of the physics of failure in the post-breakdown regime of high-κ dielectric-based conventional logic transistors having a metal–insulator–semiconductor (MIS) structure to interpret the mechanism of resistive switching in resistive random-access memory (RRAM) technology metal–insulator–metal (MIM) stacks. Oxygen vacancies, gate metal migration and metal filament formation in the gate dielectric which constitute the chemistry of breakdown in the post-breakdown stage of logic gate stacks are attributed to be the mechanisms responsible for the SET process in RRAM technology. In this paper, we draw an analogy between the breakdown study in logic devices and filamentation physics in resistive non-volatile memory.

  16. 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.

  17. 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.

  18. Cost of autotomy drives ontogenetic switching of anti-predator mechanisms under developmental constraints in a land snail.

    Science.gov (United States)

    Hoso, Masaki

    2012-12-07

    Autotomy of body parts offers various prey animals immediate benefits of survival in compensation for considerable costs. I found that a land snail Satsuma caliginosa of populations coexisting with a snail-eating snake Pareas iwasakii survived the snake predation by autotomizing its foot, whereas those out of the snake range rarely survived. Regeneration of a lost foot completed in a few weeks but imposed a delay of shell growth. Imprints of autotomy were found in greater than 10 per cent of S. caliginosa in the snake range but in only less than 1 per cent out of it, simultaneously demonstrating intense predation by the snakes and high efficiency of autotomy for surviving snake predation in the wild. However, in experiments, mature S. caliginosa performed autotomy less frequently. Instead of the costly autotomy, they can use defensive denticles on the inside of their shell apertures. Owing to the constraints from the additive growth of shells, most pulmonate snails can produce these denticles only when they have fully grown up. Thus, this developmental constraint limits the availability of the modified aperture, resulting in ontogenetic switching of the alternative defences. This study illustrates how costs of adaptation operate in the evolution of life-history strategies under developmental constraints.

  19. 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.

  20. CONTROL OF BOUNCING IN RF MEMS SWITCHES USING DOUBLE ELECTRODE

    KAUST Repository

    Abdul Rahim, Farhan

    2014-05-01

    MEMS based mechanical switches are seen to be the likely replacements for CMOS based switches due to the several advantages that these mechanical switches have over CMOS switches. Mechanical switches can be used in systems under extreme conditions and also provide more reliability and cause less power loss. A major problem with mechanical switches is bouncing. Bouncing is an undesirable characteristic which increases the switching time and causes damage to the switch structure affecting the overall switch life. This thesis proposes a new switch design that may be used to mitigate bouncing by using two voltage sources using a double electrode configuration. The effect of many switch’s tunable parameters is also discussed and an effective tuning technique is also provided. The results are compared to the current control schemes in literature and show that the double electrode scheme is a viable control option.

  1. An eco-epidemiological study of Morbilli-related paramyxovirus infection in Madagascar bats reveals host-switching as the dominant macro-evolutionary mechanism.

    Science.gov (United States)

    Mélade, Julien; Wieseke, Nicolas; Ramasindrazana, Beza; Flores, Olivier; Lagadec, Erwan; Gomard, Yann; Goodman, Steven M; Dellagi, Koussay; Pascalis, Hervé

    2016-04-12

    An eco-epidemiological investigation was carried out on Madagascar bat communities to better understand the evolutionary mechanisms and environmental factors that affect virus transmission among bat species in closely related members of the genus Morbillivirus, currently referred to as Unclassified Morbilli-related paramyxoviruses (UMRVs). A total of 947 bats were investigated originating from 52 capture sites (22 caves, 18 buildings, and 12 outdoor sites) distributed over different bioclimatic zones of the island. Using RT-PCR targeting the L-polymerase gene of the Paramyxoviridae family, we found that 10.5% of sampled bats were infected, representing six out of seven families and 15 out of 31 species analyzed. Univariate analysis indicates that both abiotic and biotic factors may promote viral infection. Using generalized linear modeling of UMRV infection overlaid on biotic and abiotic variables, we demonstrate that sympatric occurrence of bats is a major factor for virus transmission. Phylogenetic analyses revealed that all paramyxoviruses infecting Malagasy bats are UMRVs and showed little host specificity. Analyses using the maximum parsimony reconciliation tool CoRe-PA, indicate that host-switching, rather than co-speciation, is the dominant macro-evolutionary mechanism of UMRVs among Malagasy bats.

  2. An eco-epidemiological study of Morbilli-related paramyxovirus infection in Madagascar bats reveals host-switching as the dominant macro-evolutionary mechanism

    Science.gov (United States)

    Mélade, Julien; Wieseke, Nicolas; Ramasindrazana, Beza; Flores, Olivier; Lagadec, Erwan; Gomard, Yann; Goodman, Steven M.; Dellagi, Koussay; Pascalis, Hervé

    2016-01-01

    An eco-epidemiological investigation was carried out on Madagascar bat communities to better understand the evolutionary mechanisms and environmental factors that affect virus transmission among bat species in closely related members of the genus Morbillivirus, currently referred to as Unclassified Morbilli-related paramyxoviruses (UMRVs). A total of 947 bats were investigated originating from 52 capture sites (22 caves, 18 buildings, and 12 outdoor sites) distributed over different bioclimatic zones of the island. Using RT-PCR targeting the L-polymerase gene of the Paramyxoviridae family, we found that 10.5% of sampled bats were infected, representing six out of seven families and 15 out of 31 species analyzed. Univariate analysis indicates that both abiotic and biotic factors may promote viral infection. Using generalized linear modeling of UMRV infection overlaid on biotic and abiotic variables, we demonstrate that sympatric occurrence of bats is a major factor for virus transmission. Phylogenetic analyses revealed that all paramyxoviruses infecting Malagasy bats are UMRVs and showed little host specificity. Analyses using the maximum parsimony reconciliation tool CoRe-PA, indicate that host-switching, rather than co-speciation, is the dominant macro-evolutionary mechanism of UMRVs among Malagasy bats. PMID:27068130

  3. 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.

  4. 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.

  5. 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.

  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. 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.

  8. Resistive switching in Ag-TiO{sub 2} contacts

    Energy Technology Data Exchange (ETDEWEB)

    Ghenzi, N., E-mail: ghenzi@cnea.gov.ar [Gerencia de Investigacion y Aplicaciones, CAC, CNEA, (1650) San Martin, Pcia. de Buenos Aires (Argentina); Stoliar, P. [Gerencia de Investigacion y Aplicaciones, CAC, CNEA, (1650) San Martin, Pcia. de Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Campus Migueletes, UNSAM, Pcia. de Buenos Aires (Argentina); Fuertes, M.C. [Gerencia Quimica, CAC, CNEA, (1650) San Martin, Pcia. de Buenos Aires (Argentina); Marlasca, F.G.; Levy, P. [Gerencia de Investigacion y Aplicaciones, CAC, CNEA, (1650) San Martin, Pcia. de Buenos Aires (Argentina)

    2012-08-15

    We study the electric pulse induced resistance switching of TiO{sub 2}-Ag contacts at room temperature, exploring both unipolar and bipolar switching modes. Initially we observed unipolar response. After hundred pulsing cycles the unipolar switching response vanishes but the device can still be operated in bipolar switching regime. The underlying mechanism for resistance switching is modeled in terms of formation and rupture of filament, and movement of oxygen vacancies.

  9. 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...

  10. When global rule reversal meets local task switching: The neural mechanisms of coordinated behavioral adaptation to instructed multi-level demand changes.

    Science.gov (United States)

    Shi, Yiquan; Wolfensteller, Uta; Schubert, Torsten; Ruge, Hannes

    2018-02-01

    Cognitive flexibility is essential to cope with changing task demands and often it is necessary to adapt to combined changes in a coordinated manner. The present fMRI study examined how the brain implements such multi-level adaptation processes. Specifically, on a "local," hierarchically lower level, switching between two tasks was required across trials while the rules of each task remained unchanged for blocks of trials. On a "global" level regarding blocks of twelve trials, the task rules could reverse or remain the same. The current task was cued at the start of each trial while the current task rules were instructed before the start of a new block. We found that partly overlapping and partly segregated neural networks play different roles when coping with the combination of global rule reversal and local task switching. The fronto-parietal control network (FPN) supported the encoding of reversed rules at the time of explicit rule instruction. The same regions subsequently supported local task switching processes during actual implementation trials, irrespective of rule reversal condition. By contrast, a cortico-striatal network (CSN) including supplementary motor area and putamen was increasingly engaged across implementation trials and more so for rule reversal than for nonreversal blocks, irrespective of task switching condition. Together, these findings suggest that the brain accomplishes the coordinated adaptation to multi-level demand changes by distributing processing resources either across time (FPN for reversed rule encoding and later for task switching) or across regions (CSN for reversed rule implementation and FPN for concurrent task switching). © 2017 Wiley Periodicals, Inc.

  11. 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....

  12. 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.

  13. Gothic aortic arch and cardiac mechanics in young patients after arterial switch operation for d-transposition of the great arteries.

    Science.gov (United States)

    Di Salvo, Giovanni; Bulbul, Ziad; Pergola, Valeria; Issa, Ziad; Siblini, Ghassan; Muhanna, Nisreen; Galzerano, Domenico; Fadel, Bahaa; Al Joufan, Mansour; Al Fayyadh, Majid; Al Halees, Zohair

    2017-08-15

    In patients who have undergone arterial switch operation (ASO) for d-transposition of the great arteries a gothic aortic arch (GA) morphology has been found and it has been associated with abnormal aortic bio-elastic properties. GA is frequent in ASO patients and may have an impact on cardiac mechanics. Our study aims were to assess 1- the occurrence of GA in a large sample of patients after ASO; 2- the association between GA and aortic bio-elastic properties; and 3- the impact of GA on left ventricular (LV) function using speckle tracking echocardiography (STE). We studied one hundred and five asymptomatic patients, who have undergone first stage ASO for d-TGA, with normal left ventricular ejection fraction (LVEF ≥53%). Forty-six (44%) patients showed a GA (mean age 11.5±7.2years, 26 males) while fifty-nine (56%) patients (mean age 9.6±6.7years, 37 males) did not present GA. The two groups were comparable for age, sex, BSA, and office blood pressure values. In group GA aortic root was significantly dilated (27.4±7.5mm vs. 21.2±6.9mm, p<0.0001), aortic stiffness index (Group GA=1.8±1.2 vs. 1.4±0.7, p=0.025) was significantly increased, left atrial volume was larger (p=0.0145), global longitudinal strain (Group GA=-18.4±2.5% vs. -20.1±3.3%, p=0.012) and basal LV longitudinal strains (Group GA=-16.9±4.8% vs. -20.4±7.0%, p=0.013) were significantly reduced. After ASO the presence of a GA is associated with a significantly dilated aortic root, stiffer aortic wall, larger left atrial volume, and worse LV longitudinal systolic deformations, well known predictors of cardiovascular morbidity and mortality. Copyright © 2017 Elsevier B.V. All rights reserved.

  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. 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.

  16. The preparation effect in task switching: carryover of SOA.

    Science.gov (United States)

    Altmann, Erik M

    2004-01-01

    A common finding in task-switching studies is switch preparation (commonly known as the preparation effect), in which a longer interval between task cue and trial stimulus (i.e., a longer stimulus onset asynchrony, or SOA) reduces the cost of switching to a different task. Three experiments link switch preparation to within-subjects manipulations of SOA. In Experiment 1, SOA was randomized within subjects, producing switch preparation that was more pronounced when the SOA switched from the previous trial than when the SOA repeated. In Experiment 2, SOA was blocked within subjects, producing switch preparation but not on the first block of trials. In Experiment 3, SOA was manipulated between subjects with sufficient statistical power to detect switch preparation, but the effect was absent. The results favor an encoding view of cognitive control, but show that any putative switching mechanism reacts lazily when exposed to only one SOA.

  17. 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

  18. 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.

  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. Challenges in Switching SiC MOSFET without Ringing

    DEFF Research Database (Denmark)

    Li, Helong; Munk-Nielsen, Stig

    2014-01-01

    Switching SiC MOSFET without ringing in high frequency applications is important for meeting the EMI (ElectroMagnetic Interference) standard. Achieving a clean switching waveform of SiC MOSFET without additional components is becoming a challenge. In this paper, the switching oscillation mechanism...

  1. 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....

  2. Improved resistive switching phenomena and mechanism using Cu-Al alloy in a new Cu:AlO{sub x}/TaO{sub x}/TiN structure

    Energy Technology Data Exchange (ETDEWEB)

    Roy, S. [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan (China); Maikap, S., E-mail: sidhu@mail.cgu.edu.tw [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan (China); Sreekanth, G.; Dutta, M.; Jana, D. [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan (China); Chen, Y.Y.; Yang, J.R. [Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China)

    2015-07-15

    Highlights: • Cu:AlO{sub x} alloy is used for the first time to have defective TaO{sub x} film. • A relation in between formation voltage and RESET current has been developed. • A switching mechanism based on a thinner with dense Cu filament is demonstrated. • Good uniformity with yield of >90% and long cycles using 1 ms pulse are obtained. - Abstract: Improved resistive switching phenomena such as device-to-device uniformity, lower formation voltage (2.8 V) and RESET current, >500 program/erase cycles, longer read endurance of >10{sup 6} cycles with a program/erase pulse width of 1 μs, and data retention of >225 h under a low current compliance of 300 μA have been discussed by using Cu-Al alloy in Cu:AlO{sub x}/TaO{sub x}/TiN conductive bridging resistive random access memory (CBRAM) device for the first time. The switching mechanism is based on a thinner with dense Cu filament formation/dissolution through the defects in the Cu:AlO{sub x}/TaO{sub x}/TiN structure owing to enhance memory characteristics. These characteristics have been confirmed by measuring randomly picked 100 devices having via-hole size of 0.4 × 0.4 μm{sup 2}. The Cu-Al alloy becomes Cu:AlO{sub x} buffer layer and Ta{sub 2}O{sub 5} becomes TaO{sub x} switching layer owing to Gibbs free energy dependency. All layers and elements are observed by high-resolution transmission electron microscope (HRTEM) image and energy dispersive X-ray spectroscopy (EDX). By developing a numerical equation in between RESET current and formation voltage, it is found that a higher rate of Cu migration is observed owing to both the defective switching layer and larger size, which results a lower formation voltage and RESET current of the Cu:AlO{sub x}/TaO{sub x}/TiN structure, as compared to Cu/Ta{sub 2}O{sub 5}/TiN under external positive bias on the Cu electrode. This simple Cu:AlO{sub x}/TaO{sub x}/TiN CBRAM device is useful for future nanoscale non-volatile memory application.

  3. Evolution of resistive switching mechanism through H2O2 sensing by using TaOx-based material in W/Al2O3/TaOx/TiN structure

    Science.gov (United States)

    Chakrabarti, Somsubhra; Panja, Rajeswar; Roy, Sourav; Roy, Anisha; Samanta, Subhranu; Dutta, Mrinmoy; Ginnaram, Sreekanth; Maikap, Siddheswar; Cheng, Hsin-Ming; Tsai, Ling-Na; Chang, Ya-Ling; Mahapatra, Rajat; Jana, Debanjan; Qiu, Jian-Tai; Yang, Jer-Ren

    2018-03-01

    Understanding of resistive switching mechanism through H2O2 sensing and improvement of switching characteristics by using TaOx-based material in W/Al2O3/TaOx/TiN structure have been reported for the first time. Existence of amorphous Al2O3/TaOx layer in the RRAM devices has been confirmed by transmission electron microscopy. By analyzing the oxidation states of Ta2+/Ta5+ for TaOx switching material and W0/W6+ for WOx layer at the W/TaOx interface through X-ray photoelectron spectroscopy and H2O2 sensing, the reduction-oxidation mechanism under Set/Reset occurs only in the TaOx layer for the W/Al2O3/TaOx/TiN structures. This leads to higher Schottky barrier height at the W/Al2O3 interface (0.54 eV vs. 0.46 eV), higher resistance ratio, and long program/erase endurance of >108 cycles with 100 ns pulse width at a low operation current of 30 μA. Stable retention of more than 104 s at 85 °C is also obtained. Using conduction mechanism and reduction-oxidation reaction, current-voltage characteristic has been simulated. Both TaOx and WOx membranes have high pH sensitivity values of 47.65 mV/pH and 49.25 mV/pH, respectively. Those membranes can also sense H2O2 with a low concentration of 1 nM in an electrolyte-insulator-semiconductor structure because of catalytic activity, while the Al2O3 membrane does not show sensing. The TaOx material in W/Al2O3/TaOx/TiN structure does not show only a path towards high dense, small size memory application with understanding of switching mechanism but also can be used for H2O2 sensors.

  4. Ultra High-Speed Radio Frequency Switch Based on Photonics.

    Science.gov (United States)

    Ge, Jia; Fok, Mable P

    2015-11-26

    Microwave switches, or Radio Frequency (RF) switches have been intensively used in microwave systems for signal routing. Compared with the fast development of microwave and wireless systems, RF switches have been underdeveloped particularly in terms of switching speed and operating bandwidth. In this paper, we propose a photonics based RF switch that is capable of switching at tens of picoseconds speed, which is hundreds of times faster than any existing RF switch technologies. The high-speed switching property is achieved with the use of a rapidly tunable microwave photonic filter with tens of gigahertz frequency tuning speed, where the tuning mechanism is based on the ultra-fast electro-optics Pockels effect. The RF switch has a wide operation bandwidth of 12 GHz and can go up to 40 GHz, depending on the bandwidth of the modulator used in the scheme. The proposed RF switch can either work as an ON/OFF switch or a two-channel switch, tens of picoseconds switching speed is experimentally observed for both type of switches.

  5. Resistance switching mechanism of La{sub 0.8}Sr{sub 0.2}MnO{sub 3−δ} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Luo, X.D. [School of Metallurgy and Materials Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Chongqing Key Laboratory of Nano/Micro Composite Materials and Devices, Chongqing 401331 (China); Gao, R.L., E-mail: gaorongli2008@163.com [School of Metallurgy and Materials Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Chongqing Key Laboratory of Nano/Micro Composite Materials and Devices, Chongqing 401331 (China); Fu, C.L.; Cai, W.; Chen, G.; Deng, X.L. [School of Metallurgy and Materials Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Chongqing Key Laboratory of Nano/Micro Composite Materials and Devices, Chongqing 401331 (China); Zhang, H.R; Sun, J.R. [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Science, Beijing 100190 (China)

    2016-02-15

    Effects of oxygen vacancies on the electrical transport properties of oxygen stoichiometric La{sub 0.8}Sr{sub 0.2}MnO{sub 3} and oxygen-deficient La{sub 0.8}Sr{sub 0.2}MnO{sub 3−δ} films have been investigated. The result presents that the oxygen-deficient films annealed in vacuum show obvious increase of resistance and lattice parameter. With the sweeping voltage or temperature increasing, the resistance exhibits obvious bipolar switching effect, no forming process was needed. Oxygen deficiency in the annealed film leads to the formation of a structural disorder in the Mn–O–Mn conduction channel due to the accumulation of oxygen vacancies under high external electric field or temperatures and hence is believed to be responsible for the bipolar resistance switching effect and the enhanced resistivity compared with oxygen stoichiometric La{sub 0.8}Sr{sub 0.2}MnO{sub 3} film. These results may be important for practical applications in photoelectric or storage devices and point to a useful direction for other oxidizing materials.

  6. Diffusional mechanisms augment the fluorine MR relaxation in paramagnetic perfluorocarbon nanoparticles that provides a "relaxation switch" for detecting cellular endosomal activation.

    Science.gov (United States)

    Hu, Lingzhi; Zhang, Lei; Chen, Junjie; Lanza, Gregory M; Wickline, Samuel A

    2011-09-01

    To develop a physical model for the (19)F relaxation enhancement in paramagnetic perfluorocarbon nanoparticles (PFC NP) and demonstrate its application in monitoring cellular endosomal functionality through a "(19)F relaxation switch" phenomenon. An explicit expression for (19)F longitudinal relaxation enhancement was derived analytically. Monte-Carlo simulation was performed to confirm the gadolinium-induced magnetic field inhomogeneity inside the PFC NP. Field-dependent T(1) measurements for three types of paramagnetic PFC NPs were carried out to validate the theoretical prediction. Based on the physical model, (19)F and (1)H relaxation properties of macrophage internalized paramagnetic PFC NPs were measured to evaluate the intracellular process of NPs by macrophages in vitro. The theoretical description was confirmed experimentally by field-dependent T(1) measurements. The shortening of (19)F T(1) was found to be attributed to the Brownian motion of PFC molecules inside the NP in conjunction with their ability to permeate into the lipid surfactant coating. A dramatic change of (19)F T(1) was observed upon endocytosis, revealing the transition from intact bound PFC NP to processed constituents. The proposed first-principle analysis of (19)F spins in paramagnetic PFC NP relates their structural parameters to the special MR relaxation features. The demonstrated "(19)F relaxation switch" phenomenon is potentially useful for monitoring cellular endosomal functionality. Copyright © 2011 Wiley-Liss, Inc.

  7. Resistance switching mechanism of La0.8Sr0.2MnO3−δ thin films

    International Nuclear Information System (INIS)

    Luo, X.D.; Gao, R.L.; Fu, C.L.; Cai, W.; Chen, G.; Deng, X.L.; Zhang, H.R; Sun, J.R.

    2016-01-01

    Effects of oxygen vacancies on the electrical transport properties of oxygen stoichiometric La 0.8 Sr 0.2 MnO 3 and oxygen-deficient La 0.8 Sr 0.2 MnO 3−δ films have been investigated. The result presents that the oxygen-deficient films annealed in vacuum show obvious increase of resistance and lattice parameter. With the sweeping voltage or temperature increasing, the resistance exhibits obvious bipolar switching effect, no forming process was needed. Oxygen deficiency in the annealed film leads to the formation of a structural disorder in the Mn–O–Mn conduction channel due to the accumulation of oxygen vacancies under high external electric field or temperatures and hence is believed to be responsible for the bipolar resistance switching effect and the enhanced resistivity compared with oxygen stoichiometric La 0.8 Sr 0.2 MnO 3 film. These results may be important for practical applications in photoelectric or storage devices and point to a useful direction for other oxidizing materials.

  8. Mechanism for Controlling the Dimer-Monomer Switch and Coupling Dimerization to Catalysis of the Severe Acute Respiratory Syndrome Coronavirus 3C-Like Protease

    Energy Technology Data Exchange (ETDEWEB)

    Shi,J.; Sivaraman, J.; Song, J.

    2008-01-01

    Unlike 3C protease, the severe acute respiratory syndrome coronavirus (SARS-CoV) 3C-like protease (3CLpro) is only enzymatically active as a homodimer and its catalysis is under extensive regulation by the unique extra domain. Despite intense studies, two puzzles still remain: (i) how the dimer-monomer switch is controlled and (ii) why dimerization is absolutely required for catalysis. Here we report the monomeric crystal structure of the SARS-CoV 3CLpro mutant R298A at a resolution of 1.75 Angstroms . Detailed analysis reveals that Arg298 serves as a key component for maintaining dimerization, and consequently, its mutation will trigger a cooperative switch from a dimer to a monomer. The monomeric enzyme is irreversibly inactivated because its catalytic machinery is frozen in the collapsed state, characteristic of the formation of a short 310-helix from an active-site loop. Remarkably, dimerization appears to be coupled to catalysis in 3CLpro through the use of overlapped residues for two networks, one for dimerization and another for the catalysis.

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. 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...

  14. 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.

  15. 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.

  16. Switching terahertz wave with grating-coupled Kretschmann configuration.

    Science.gov (United States)

    Jiu-Sheng, Li

    2017-08-07

    We present a terahertz wave switch utilizing Kretschmann configuration which consists of high-refractive-index prism-liquid crystal-periodically grooved metal grating. The switching mechanism of the terahertz switch is based on spoof surface plasmon polariton (SSPP) excitation in the attenuated total reflection regime by changing the liquid crystal refractive index. The results highlighted the fact that the feasibility to "tune" the attenuated total reflection terahertz wave intensity by using the external applied bias voltage. The extinction ratio of the terahertz switch reaches 31.48dB. The terahertz switch has good control ability and flexibility, and can be used in potential terahertz free space device systems.

  17. Resistive switching mechanism of ZnO/ZrO2-stacked resistive random access memory device annealed at 300 °C by sol-gel method with forming-free operation

    Science.gov (United States)

    Jian, Wen-Yi; You, Hsin-Chiang; Wu, Cheng-Yen

    2018-01-01

    In this work, we used a sol-gel process to fabricate a ZnO-ZrO2-stacked resistive switching random access memory (ReRAM) device and investigated its switching mechanism. The Gibbs free energy in ZnO, which is higher than that in ZrO2, facilitates the oxidation and reduction reactions of filaments in the ZnO layer. The current-voltage (I-V) characteristics of the device revealed a forming-free operation because of nonlattice oxygen in the oxide layer. In addition, the device can operate under bipolar or unipolar conditions with a reset voltage of 0 to ±2 V, indicating that in this device, Joule heating dominates at reset and the electric field dominates in the set process. Furthermore, the characteristics reveal why the fabricated device exhibits a greater discrete distribution phenomenon for the set voltage than for the reset voltage. These results will enable the fabrication of future ReRAM devices with double-layer oxide structures with improved characteristics.

  18. 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

  19. 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 ...

  20. 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.

  1. Relationships between strategy switching and strategy switch costs in young and older adults: a study in arithmetic problem solving.

    Science.gov (United States)

    Taillan, Julien; Ardiale, Eléonore; Lemaire, Patrick

    2015-01-01

    BACKGROUND/STUDY CONTEXT: This study investigated age-related differences in within-item strategy switching (i.e., revising initial strategy choices to select a better strategy while solving a given problem) and in strategy switch costs (i.e., longer latencies when participants switch strategies than when they do not switch strategy during strategy execution). In a computational estimation task, participants had to give approximate products to two-digit multiplication problems (e.g., 41×67) while rounding up (i.e., do 50×70 for 41×67) or rounding down (i.e., do 40×60 for 41×67) operands to their nearest decades. After executing a cued strategy during 1000 ms, participants had the possibility to switch to another strategy (or repeat the same strategy) in a selection condition. In an execution condition, participants were forced to repeat the same strategy or to switch to another strategy. It was found that (1) older adults were less able than young adults to switch strategy after starting to execute a cued strategy (36.1% vs. 45.8%); (2) older adults showed larger switch costs than young adults (422 vs. 223 ms); and (3) strategy switches and strategy switch costs correlated in older adults but not in young adults. These findings have important implications for our understanding of the mechanisms underlying within-item strategy switching and aging effects on these mechanisms as well as, more generally, of strategic variations during cognitive aging.

  2. Photo-stimulated resistive switching of ZnO nanorods

    International Nuclear Information System (INIS)

    Park, Jinjoo; Lee, Seunghyup; Yong, Kijung

    2012-01-01

    Resistive switching memory devices are promising candidates for emerging memory technologies because they yield outstanding device performance. Storage mechanisms for achieving high-density memory applications have been developed; however, so far many of them exhibit typical resistive switching behavior from the limited controlling conditions. In this study, we introduce photons as an unconventional stimulus for activating resistive switching behaviors. First, we compare the resistive switching behavior in light and dark conditions to describe how resistive switching memories can benefit from photons. Second, we drive the switching of resistance not by the electrical stimulus but only by the modulation of photon. ZnO nanorods were employed as a model system to demonstrate photo-stimulated resistive switching in high-surface-area nanomaterials, in which photo-driven surface states strongly affect their photoconductivity and resistance states. (paper)

  3. 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.

  4. 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

  5. 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

  6. Bilingual Language Switching and the Frontal Lobes: Modulatory Control in Language Selection.

    Science.gov (United States)

    Meuter, Renata; Humphreys, Glyn; Rumiati, Raffaella

    2002-01-01

    Discusses the brain mechanisms mediating the switching of languages in bilingual subjects. To ascertain the brain mechanisms mediating the control of language switching, switching was examined in a bilingual patient with frontal lobe damage and impaired control processes. (Author/VWL)

  7. Investigation of Random Switching Driven by a Poisson Point Process

    DEFF Research Database (Denmark)

    Simonsen, Maria; Schiøler, Henrik; Leth, John-Josef

    2015-01-01

    This paper investigates the switching mechanism of a two-dimensional switched system, when the switching events are generated by a Poisson point process. A model, in the shape of a stochastic process, for such a system is derived and the distribution of the trajectory's position is developed...... together with marginal density functions for the coordinate functions. Furthermore, the joint probability distribution is given explicitly....

  8. 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.

  9. 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.

  10. 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

  11. 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.

  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. Hybrid Optical Switching for Data Center Networks

    Directory of Open Access Journals (Sweden)

    Matteo Fiorani

    2014-01-01

    Full Text Available Current data centers networks rely on electronic switching and point-to-point interconnects. When considering future data center requirements, these solutions will raise issues in terms of flexibility, scalability, performance, and energy consumption. For this reason several optical switched interconnects, which make use of optical switches and wavelength division multiplexing (WDM, have been recently proposed. However, the solutions proposed so far suffer from low flexibility and are not able to provide service differentiation. In this paper we introduce a novel data center network based on hybrid optical switching (HOS. HOS combines optical circuit, burst, and packet switching on the same network. In this way different data center applications can be mapped to the optical transport mechanism that best suits their traffic characteristics. Furthermore, the proposed HOS network achieves high transmission efficiency and reduced energy consumption by using two parallel optical switches. We consider the architectures of both a traditional data center network and the proposed HOS network and present a combined analytical and simulation approach for their performance and energy consumption evaluation. We demonstrate that the proposed HOS data center network achieves high performance and flexibility while considerably reducing the energy consumption of current solutions.

  15. 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

  16. 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.

  17. A novel mathematical model of ATM/p53/NF- κB pathways points to the importance of the DDR switch-off mechanisms.

    Science.gov (United States)

    Jonak, Katarzyna; Kurpas, Monika; Szoltysek, Katarzyna; Janus, Patryk; Abramowicz, Agata; Puszynski, Krzysztof

    2016-08-15

    Ataxia telangiectasia mutated (ATM) is a detector of double-strand breaks (DSBs) and a crucial component of the DNA damage response (DDR) along with p53 and NF- κB transcription factors and Wip1 phosphatase. Despite the recent advances in studying the DDR, the mechanisms of cell fate determination after DNA damage induction is still poorly understood. To investigate the importance of various DDR elements with particular emphasis on Wip1, we developed a novel mathematical model of ATM/p53/NF- κB pathways. Our results from in silico and in vitro experiments performed on U2-OS cells with Wip1 silenced to 25 % (Wip1-RNAi) revealed a strong dependence of cellular response to DNA damages on this phosphatase. Notably, Wip1-RNAi cells exhibited lower resistance to ionizing radiation (IR) resulting in smaller clonogenicity and higher apoptotic fraction. In this article, we demonstrated that Wip1 plays a role as a gatekeeper of apoptosis and influences the pro-survival behaviour of cells - the level of Wip1 increases to block the apoptotic decision when DNA repair is successful. Moreover, we were able to verify the dynamics of proteins and transcripts, apoptotic fractions and cells viability obtained from stochastic simulations using in vitro approaches. Taken together, we demonstrated that the model can be successfully used in prediction of cellular behaviour after exposure to IR. Thus, our studies may provide further insights into key elements involved in the underlying mechanisms of the DDR.

  18. The Role of Code-Switching in Bilingual Creativity

    Science.gov (United States)

    Kharkhurin, Anatoliy V.; Wei, Li

    2015-01-01

    This study further explores the theme of bilingual creativity with the present focus on code-switching. Specifically, it investigates whether code-switching practice has an impact on creativity. In line with the previous research, selective attention was proposed as a potential cognitive mechanism, which on the one hand would benefit from…

  19. The mechanism of switching from an acidogenic to butanol-acetone fermentation by Clostridium acetobutylicum. Technical progress report, July 1990--December 1992

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, P.

    1992-12-31

    The overall objective of this project is to elucidate the detailed mechanism by which solvent-forming bacteria such as Clostridium acetobutylicum regulate the well-known shift in fermentation pathway between alcohol-acetone and organic acid production. It is desired to eventually isolate and describe: (1) the regulatory genes and protein elements that determine induction of synthesis of the solvent-pathway enzymes; and (2) how this regulation system interacts with the sporulatin induction and development program and with related pathways such as granulse and exopolysaccharide formation in clostridia. A working model forhow clostridial control systems work can be derived from recent research on stress systems in E. coli and sporulation in Bacillus subtilis.

  20. 49 CFR 236.303 - Control circuits for signals, selection through circuit controller operated by switch points or...

    Science.gov (United States)

    2010-10-01

    ... circuit controller operated by switch points or by switch locking mechanism. 236.303 Section 236.303... § 236.303 Control circuits for signals, selection through circuit controller operated by switch points...-point frogs and derails shall be selected through circuit controller operated directly by switch points...

  1. 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.

  2. 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.

  3. 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.

  4. 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...

  5. 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

  6. 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.

  7. Resistance switching in silver - manganite contacts

    International Nuclear Information System (INIS)

    Gomez-Marlasca, F; Levy, P

    2009-01-01

    We investigate the electric pulse induced resistance switching in a transition metal oxide-metal contact at room temperature - a non volatile, reversible and multilevel memory device. Using a simple multiterminal configuration, we find that the complementary effect -in which the contact resistance of each pulsed electrode displays variations of opposite sign- is strongly influenced by the history of the pulsing procedure. Loops performed by varying the magnitude and sign of the stimulus at each pulsed electrode allow to disentangle their sole contribution at different stages of the process. Electromigration of oxygen ions and vacancies is discussed as participating at the core of the underlying mechanisms for resistance switching.

  8. Complementary resistive switching in BaTiO{sub 3}/NiO bilayer with opposite switching polarities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Institut d’Electronique de Micro-électronique et de Nanotechnologie (IEMN), CNRS, Université des Sciences et Technologies de Lille, avenue Poincaré, BP 60069, 59652, Villeneuve d’Ascq cedex (France); Wei, Xianhua, E-mail: weixianhua@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Lei, Yao [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronics Science and Technology of China, Chengdu 610054 (China); Yuan, Xincai [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zeng, Huizhong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronics Science and Technology of China, Chengdu 610054 (China)

    2016-12-15

    Graphical abstract: Au/BaTiO{sub 3}/NiO/Pt bilayer device shows complementary resistive switching (CRS) without electroforming which is mainly ascribed to anti-serial stack of two RRAM cells with bipolar behaviors. - Highlights: • Complementary resistive switching (CRS) has been investigated in Au/BaTiO{sub 3}/NiO/Pt by stacking the two elements with different switching types. • The realization of complementary resistive switching (CRS) is mainly ascribed to the anti-serial stack of two RRAM cells with bipolar behaviors. • Complementary resistive switching (CRS) in bilayer is effective to solve the sneak current problem briefly and economically. - Abstract: Resistive switching behaviors have been investigated in the Au/BaTiO{sub 3}/NiO/Pt structure by stacking the two elements with different switching types. The conducting atomic force microscope measurements on BaTiO{sub 3} thin films and NiO thin films suggest that with the same active resistive switching region, the switching polarities in the two semiconductors are opposite to each other. It is in agreement with the bipolar hysteresis I–V curves with opposite switching polarities for single-layer devices. The bilayer devices show complementary resistive switching (CRS) without electroforming and unipolar resistive switching (URS) after electroforming. The coexistence of CRS and URS is mainly ascribed to the co-effect of electric field and Joule heating mechanisms, indicating that changeable of resistance in this device is dominated by the redistribution of oxygen vacancies in BaTiO{sub 3} and the formation, disruption, restoration of conducting filaments in NiO. CRS in bilayer with opposite switching polarities is effective to solve the sneak current without the introduction of any selector elements or an additional metal electrode.

  9. A nanoplasmonic switch based on molecular machines

    KAUST Repository

    Zheng, Yue Bing

    2009-06-01

    We aim to develop a molecular-machine-driven nanoplasmonic switch for its use in future nanophotonic integrated circuits (ICs) that have applications in optical communication, information processing, biological and chemical sensing. Experimental data show that an Au nanodisk array, coated with rotaxane molecular machines, switches its localized surface plasmon resonances (LSPR) reversibly when it is exposed to chemical oxidants and reductants. Conversely, bare Au nanodisks and disks coated with mechanically inert control compounds, do not display the same switching behavior. Along with calculations based on time-dependent density functional theory (TDDFT), these observations suggest that the nanoscale movements within surface-bound "molecular machines" can be used as the active components in plasmonic devices. ©2009 IEEE.

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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...

  15. 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

  16. Two Bistable Switches Govern M Phase Entry.

    Science.gov (United States)

    Mochida, Satoru; Rata, Scott; Hino, Hirotsugu; Nagai, Takeharu; Novák, Béla

    2016-12-19

    The abrupt and irreversible transition from interphase to M phase is essential to separate DNA replication from chromosome segregation. This transition requires the switch-like phosphorylation of hundreds of proteins by the cyclin-dependent kinase 1 (Cdk1):cyclin B (CycB) complex. Previous studies have ascribed these switch-like phosphorylations to the auto-activation of Cdk1:CycB through the removal of inhibitory phosphorylations on Cdk1-Tyr15 [1, 2]. The positive feedback in Cdk1 activation creates a bistable switch that makes mitotic commitment irreversible [2-4]. Here, we surprisingly find that Cdk1 auto-activation is dispensable for irreversible, switch-like mitotic entry due to a second mechanism, whereby Cdk1:CycB inhibits its counteracting phosphatase (PP2A:B55). We show that the PP2A:B55-inhibiting Greatwall (Gwl)-endosulfine (ENSA) pathway is both necessary and sufficient for switch-like phosphorylations of mitotic substrates. Using purified components of the Gwl-ENSA pathway in a reconstituted system, we found a sharp Cdk1 threshold for phosphorylation of a luminescent mitotic substrate. The Cdk1 threshold to induce mitotic phosphorylation is distinctly higher than the Cdk1 threshold required to maintain these phosphorylations-evidence for bistability. A combination of mathematical modeling and biochemical reconstitution show that the bistable behavior of the Gwl-ENSA pathway emerges from its mutual antagonism with PP2A:B55. Our results demonstrate that two interlinked bistable mechanisms provide a robust solution for irreversible and switch-like mitotic entry. Copyright © 2016 Elsevier Ltd. All rights reserved.

  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. On life assessment of high reliability high power optical switch

    Science.gov (United States)

    Xu, Yuanjian; Chu, Peter

    2014-09-01

    High data rate and long range free space lasercom links require multi-watt optical transmitter power, which creates a need for high power redundancy switches to ensure high payload reliability. A high power optical switch (HPOS) with less than 0.15 dB loss and capable of switching more than 40 watts of optical power in a single mode fiber has been previously demonstrated in the Transformational Satellite Communication System program. Prototype switches, in either 1x2 or 2x2 configuration, have been subjected to pyro-shock test, vibration test, and vacuum operation. These switches showed no performance degradation as a result of these tests. Three prototypes went through 60,000 35-watt switching cycles and over 30 million low power switching cycles, and the switches showed no mechanical failure. The HPOS life is about 3.2 million switching cycles with a definition of 3-dB degradation in on/off extinction ratio, which is well suited for space applications.

  19. 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

  20. 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.

  1. Deformation and recrystallization mechanisms in actively extruding salt fountain: Microstructural evidence for a switch in deformation mechanisms with increased availability of meteoric water and decreased grain size (Qum Kuh, central Iran)

    Czech Academy of Sciences Publication Activity Database

    Desbois, G.; Závada, Prokop; Schléder, Z.; Urai, J. L.

    2010-01-01

    Roč. 32, č. 4 (2010), s. 580-594 ISSN 0191-8141 Grant - others:Deutsche Forschungsgemeinschaft(DE) UR 64/9-2 Institutional research plan: CEZ:AV0Z30120515 Keywords : rocksalt * salt extrusion * gamma - irradiation * deformation mechanisms * microstructure Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.911, year: 2010

  2. 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...

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. "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.

  8. Unipolar resistive switching behaviors in amorphous lutetium oxide films

    Science.gov (United States)

    Gao, Xu; Xia, Yidong; Xu, Bo; Kong, Jizhou; Guo, Hongxuan; Li, Kui; Li, Haitao; Xu, Hanni; Chen, Kai; Yin, Jiang; Liu, Zhiguo

    2010-10-01

    The resistive switching properties in the amorphous Lu2O3 films deposited by pulsed laser deposition have been investigated. Well unipolar switching behaviors of Pt/Lu2O3/Pt stacks were obtained. The memory cells exhibited a high resistance ratio over 1×103, fast programming speed within 30 ns, and no obvious degradation after an endurance of 300 switching cycles and a duration of 3.2×106 s. The first-principles calculation indicates that the oxygen vacancies in cubic Lu2O3 will form defective energy level below the bottom of conduction band, and reduce the band gap. The absence of grain boundaries in the amorphous Lu2O3 films helps us attribute the switching mechanism of such stacks to the possible redistribution of defects related to oxygen vacancies along the filamentary paths during the resistive switching process.

  9. Low Actuating Voltage Spring-Free RF MEMS SPDT Switch

    Directory of Open Access Journals (Sweden)

    Deepak Bansal

    2016-01-01

    Full Text Available RF MEMS devices are known to be superior to their solid state counterparts in terms of power consumption and electromagnetic response. Major limitations of MEMS devices are their low switching speed, high actuation voltage, larger size, and reliability. In the present paper, a see-saw single pole double throw (SPDT RF MEMS switch based on anchor-free mechanism is proposed which eliminates the above-mentioned disadvantages. The proposed switch has a switching time of 394 nsec with actuation voltage of 5 V. Size of the SPDT switch is reduced by utilizing a single series capacitive switch compared to conventional switches with capacitive and series combinations. Reliability of the switch is improved by adding floating metal and reducing stiction between the actuating bridge and transmission line. Insertion loss and isolation are better than −0.6 dB and −20 dB, respectively, for 1 GHz to 20 GHz applications.

  10. Mechanism

    Directory of Open Access Journals (Sweden)

    Yao Yu

    2010-01-01

    Full Text Available The kinematics analysis method of a novel 3-DOF wind tunnel mechanism based on cable-driven parallel mechanism is provided. Rodrigues' parameters are applied to express the transformation matrix of the wire-driven mechanism in the paper. The analytical forward kinematics model is described as three quadratic equations using three Rodridgues' parameters based on the fundamental theory of parallel mechanism. Elimination method is used to remove two of the variables, so that an eighth-order polynomial with one variable is derived. From the equation, the eight sets of Rodridgues' parameters and corresponding Euler angles for the forward kinematical problem can be obtained. In the end, numerical example of both forward and inverse kinematics is included to demonstrate the presented forward-kinematics solution method. The numerical results show that the method for the position analysis of this mechanism is effective.

  11. 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...

  12. 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....

  13. Helical EMG module with explosive current opening switches

    International Nuclear Information System (INIS)

    Chernyshev, V.K.; Vakhrushev, V.V.; Volkov, G.I.; Ivanov, V.A.; Fetisov, I.K.

    1990-01-01

    To carry out the experimental work to study plasma properties, electromagnetic sources with 10 6 to 10 8 J of stored energy delivered to the load in microsecond time, are required. Among the current electromagnetic storage devices, the explosive magnetic generators (EMG) are of the largest energy capacity. The disadvantages of this type of generators is relatively long time (ten of microseconds) of electromagnetic energy cumulation in the deformable circuit. To reduce the time of energy transfer to the load to a microsecond range the switching scheme is generally used, where the cumulation circuit and that of the load are separated and connected in parallel via a switching element (opening switch) providing generation of desired power. In this paper, some ways and means of designing opening switches to generate high current pulses have been investigated. The opening switches to generate high current pulses have been investigated. The opening switches which operation is based on mechanic destruction of the conductor using high explosive, have the highest and most reliable performance. The authors have explored the mechanic disruption of a thin conductor (foil), the technique based on throwing the foil at the ribbed barrier of electric insulator material. The report presents the data obtained in studying the operation of this type of opening switch having cylindrical shape, 200 mm in diameter and 200 mm long, designed for generation of 5.5 MA current pulse in the load

  14. Resistive Switching Characteristics in Electrochemically Synthesized ZnO Films

    Directory of Open Access Journals (Sweden)

    Shuhan Jing

    2015-04-01

    Full Text Available The semiconductor industry has long been seeking a new kind of non-volatile memory technology with high-density, high-speed, and low-power consumption. This study demonstrated the electrochemical synthesis of ZnO films without adding any soft or hard templates. The effect of deposition temperatures on crystal structure, surface morphology and resistive switching characteristics were investigated. Our findings reveal that the crystallinity, surface morphology and resistive switching characteristics of ZnO thin films can be well tuned by controlling deposition temperature. A conducting filament based model is proposed to explain the switching mechanism in ZnO thin films.

  15. Chemical switches and logic gates based on surface modified semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Konrad, Szacilowski; Wojciech, Macyk [Jagiellonian Univ., Dept. of Chemistry, Krakow (Poland)

    2006-02-15

    Photoelectrochemical properties of multicomponent photo-electrodes based on titanium dioxide and cadmium sulfide powders modified with hexacyanoferrate complexes have been examined. Photocurrent responses were recorded as functions of applied potential and photon energy. Surprisingly, the photocurrent can be switched between positive and negative values as a result of potential or photon energy changes. This new effect called Photo Electrochemical Photocurrent Switching (PEPS) opens a possibility of new chemical switches and logic gates construction. Boolean logic analysis and a tentative mechanism of the device are discussed. (authors)

  16. Low Temperature Resistive Switching Behavior in a Manganite

    Science.gov (United States)

    Salvo, Christopher; Lopez, Melinda; Tsui, Stephen

    2012-02-01

    The development of new nonvolatile memory devices remains an important field of consumer electronics. A possible candidate is bipolar resistive switching, a method by which the resistance of a material changes when a voltage is applied. Although there is a great deal of research on this topic, not much has been done at low temperatures. In this work, we compare the room temperature and low temperature behaviors of switching in a manganite thin film. The data indicates that the switching is suppressed upon cooling to cryogenic temperatures, and the presence of crystalline charge traps is tied to the physical mechanism.

  17. Conductivity switching of labyrinth metal films at the percolation threshold

    Science.gov (United States)

    Gushchin, M. G.; Gladskikh, I. A.; Vartanyan, T. A.

    2018-01-01

    Electrical properties of silver, gold and copper films at the percolation threshold were investigated experimentally. A convenient method to obtain films at the percolation threshold that consists of two phases: deposition of metal in vacuum on a dielectric substrate and subsequent thermal annealing has been developed. The metallic films produced in this way exist in two different states: a low-conductivity state and a high-conductivity state. The films can be switched between these states by the applied voltage with hysteresis of current-voltage characteristic curves. The conductivity difference between the states reaches seven orders of magnitude. The switching threshold voltage depends on the annealing time. The switching times differ considerably for different metals. They were 200 ns for silver, 2 µs for gold, and 60 µs for copper. A plausible explanation of the switching mechanism based on the voltage induced fine mechanical deformations is suggested and discussed.

  18. Reversible electrical resistance switching in GeSbTe thin films : An electrolytic approach without amorphous-crystalline phase-change

    NARCIS (Netherlands)

    Pandian, Ramanathaswamy; Kooi, Bart J.; Palasantzas, George; De Hosson, Jeff Th. M.; Wouters, DJ; Hong, S; Soss, S; Auciello, O

    2008-01-01

    Besides the well-known resistance switching originating from the amorphous-crystalline phase-change in GeSbTe thin films, we demonstrate another switching mechanism named 'polarity-dependent resistance (PDR) switching'. 'Me electrical resistance of the film switches between a low- and high-state

  19. 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.

  20. 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

  1. Operation of a homeostatic sleep switch.

    Science.gov (United States)

    Pimentel, Diogo; Donlea, Jeffrey M; Talbot, Clifford B; Song, Seoho M; Thurston, Alexander J F; Miesenböck, Gero

    2016-08-18

    Sleep disconnects animals from the external world, at considerable risks and costs that must be offset by a vital benefit. Insight into this mysterious benefit will come from understanding sleep homeostasis: to monitor sleep need, an internal bookkeeper must track physiological changes that are linked to the core function of sleep. In Drosophila, a crucial component of the machinery for sleep homeostasis is a cluster of neurons innervating the dorsal fan-shaped body (dFB) of the central complex. Artificial activation of these cells induces sleep, whereas reductions in excitability cause insomnia. dFB neurons in sleep-deprived flies tend to be electrically active, with high input resistances and long membrane time constants, while neurons in rested flies tend to be electrically silent. Correlative evidence thus supports the simple view that homeostatic sleep control works by switching sleep-promoting neurons between active and quiescent states. Here we demonstrate state switching by dFB neurons, identify dopamine as a neuromodulator that operates the switch, and delineate the switching mechanism. Arousing dopamine caused transient hyperpolarization of dFB neurons within tens of milliseconds and lasting excitability suppression within minutes. Both effects were transduced by Dop1R2 receptors and mediated by potassium conductances. The switch to electrical silence involved the downregulation of voltage-gated A-type currents carried by Shaker and Shab, and the upregulation of voltage-independent leak currents through a two-pore-domain potassium channel that we term Sandman. Sandman is encoded by the CG8713 gene and translocates to the plasma membrane in response to dopamine. dFB-restricted interference with the expression of Shaker or Sandman decreased or increased sleep, respectively, by slowing the repetitive discharge of dFB neurons in the ON state or blocking their entry into the OFF state. Biophysical changes in a small population of neurons are thus linked to the

  2. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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…

  9. 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

  10. Dielectric breakdown of fast switching LCD shutters

    Science.gov (United States)

    Mozolevskis, Gatis; Sekacis, Ilmars; Nitiss, Edgars; Medvids, Arturs; Rutkis, Martins

    2017-02-01

    Fast liquid crystal optical shutters due to fast switching, vibrationless control and optical properties have found various applications: substitutes for mechanical shutters, 3D active shutter glasses, 3D volumetric displays and more. Switching speed depends not only on properties of liquid crystal, but also on applied electric field intensity. Applied field in the shutters can exceed >10 V/micron which may lead to dielectric breakdown. Therefore, a dielectric thin film is needed between transparent conductive electrodes in order to reduce breakdown probability. In this work we have compared electrical and optical properties of liquid crystal displays with dielectric thin films with thicknesses up to few hundred nanometers coated by flexo printing method and magnetron sputtering. Dielectric breakdown values show flexographic thin films to have higher resistance to dielectric breakdown, although sputtered coatings have better optical properties, such as higher transmission and no coloration.

  11. Filamentary model in resistive switching materials

    Science.gov (United States)

    Jasmin, Alladin C.

    2017-12-01

    The need for next generation computer devices is increasing as the demand for efficient data processing increases. The amount of data generated every second also increases which requires large data storage devices. Oxide-based memory devices are being studied to explore new research frontiers thanks to modern advances in nanofabrication. Various oxide materials are studied as active layers for non-volatile memory. This technology has potential application in resistive random-access-memory (ReRAM) and can be easily integrated in CMOS technologies. The long term perspective of this research field is to develop devices which mimic how the brain processes information. To realize such application, a thorough understanding of the charge transport and switching mechanism is important. A new perspective in the multistate resistive switching based on current-induced filament dynamics will be discussed. A simple equivalent circuit of the device gives quantitative information about the nature of the conducting filament at different resistance states.

  12. Gamma-ray irradiation of ohmic MEMS switches

    Science.gov (United States)

    Maciel, John J.; Lampen, James L.; Taylor, Edward W.

    2012-10-01

    Radio Frequency (RF) Microelectromechanical System (MEMS) switches are becoming important building blocks for a variety of military and commercial applications including switch matrices, phase shifters, electronically scanned antennas, switched filters, Automatic Test Equipment, instrumentation, cell phones and smart antennas. Low power consumption, large ratio of off-impedance to on-impedance, extreme linearity, low mass, small volume and the ability to be integrated with other electronics makes MEMS switches an attractive alternative to other mechanical and solid-state switches for a variety of space applications. Radant MEMS, Inc. has developed an electrostatically actuated broadband ohmic microswitch that has applications from DC through the microwave region. Despite the extensive earth based testing, little is known about the performance and reliability of these devices in space environments. To help fill this void, we have irradiated our commercial-off-the-shelf SPST, DC to 40 GHz MEMS switches with gamma-rays as an initial step to assessing static impact on RF performance. Results of Co-60 gamma-ray irradiation of the MEMS switches at photon energies ≥ 1.0 MeV to a total dose of ~ 118 krad(Si) did not show a statistically significant post-irradiation change in measured broadband, RF insertion loss, insertion phase, return loss and isolation.

  13. The neural basis of task switching changes with skill acquisition.

    Science.gov (United States)

    Jimura, Koji; Cazalis, Fabienne; Stover, Elena R S; Poldrack, Russell A

    2014-01-01

    Learning novel skills involves reorganization and optimization of cognitive processing involving a broad network of brain regions. Previous work has shown asymmetric costs of switching to a well-trained task vs. a poorly-trained task, but the neural basis of these differential switch costs is unclear. The current study examined the neural signature of task switching in the context of acquisition of new skill. Human participants alternated randomly between a novel visual task (mirror-reversed word reading) and a highly practiced one (plain word reading), allowing the isolation of task switching and skill set maintenance. Two scan sessions were separated by 2 weeks, with behavioral training on the mirror reading task in between the two sessions. Broad cortical regions, including bilateral prefrontal, parietal, and extrastriate cortices, showed decreased activity associated with learning of the mirror reading skill. In contrast, learning to switch to the novel skill was associated with decreased activity in a focal subcortical region in the dorsal striatum. Switching to the highly practiced task was associated with a non-overlapping set of regions, suggesting substantial differences in the neural substrates of switching as a function of task skill. Searchlight multivariate pattern analysis also revealed that learning was associated with decreased pattern information for mirror vs. plain reading tasks in fronto-parietal regions. Inferior frontal junction and posterior parietal cortex showed a joint effect of univariate activation and pattern information. These results suggest distinct learning mechanisms task performance and executive control as a function of learning.

  14. The neural basis of task switching changes with skill acquisition

    Directory of Open Access Journals (Sweden)

    Koji eJimura

    2014-05-01

    Full Text Available Learning novel skills involves reorganization and optimization of cognitive processing involving a broad network of brain regions. Previous work has shown asymmetric costs of switching to a well-trained task versus a poorly-trained task, but the neural basis of these differential switch costs is unclear. The current study examined the neural signature of task switching in the context of acquisition of new skill. Human participants alternated randomly between a novel visual task (mirror-reversed word reading and a highly practiced one (plain word reading, allowing the isolation of task switching and skill set maintenance. Two scan sessions were separated by two weeks, with behavioral training on the mirror reading task in between the two sessions. Broad cortical regions, including bilateral prefrontal, parietal, and extrastriate cortices, showed decreased activity associated with learning of the mirror reading skill. In contrast, learning to switch to the novel skill was associated with decreased activity in a focal subcortical region in the dorsal striatum. Switching to the highly practiced task was associated with a non-overlapping set of regions, suggesting substantial differences in the neural substrates of switching as a function of task skill. Searchlight multivariate pattern analysis also revealed that learning was associated with decreased pattern information for mirror versus plain reading tasks in fronto-parietal regions. Inferior frontal junction and posterior parietal cortex showed a joint effect of univariate activation and pattern information. These results suggest distinct learning mechanisms task performance and executive control as a function of learning.

  15. 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.

  16. 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).

  17. 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...

  18. Inflexible minds: impaired attention switching in recent-onset schizophrenia.

    Directory of Open Access Journals (Sweden)

    Henderikus G O M Smid

    Full Text Available Impairment of sustained attention is assumed to be a core cognitive abnormality in schizophrenia. However, this seems inconsistent with a recent hypothesis that in schizophrenia the implementation of selection (i.e., sustained attention is intact but the control of selection (i.e., switching the focus of attention is impaired. Mounting evidence supports this hypothesis, indicating that switching of attention is a bigger problem in schizophrenia than maintaining the focus of attention. To shed more light on this hypothesis, we tested whether schizophrenia patients are impaired relative to controls in sustaining attention, switching attention, or both. Fifteen patients with recent-onset schizophrenia and fifteen healthy volunteers, matched on age and intelligence, performed sustained attention and attention switching tasks, while performance and brain potential measures of selective attention were recorded. In the sustained attention task, patients did not differ from the controls on these measures. In the attention switching task, however, patients showed worse performance than the controls, and early selective attention related brain potentials were absent in the patients while clearly present in the controls. These findings support the hypothesis that schizophrenia is associated with an impairment of the mechanisms that control the direction of attention (attention switching, while the mechanisms that implement a direction of attention (sustained attention are intact.

  19. Switching on the Aire conditioner.

    Science.gov (United States)

    Matsumoto, Mitsuru

    2015-12-01

    Aire has been cloned as the gene responsible for a hereditary type of organ-specific autoimmune disease. Aire controls the expression of a wide array of tissue-restricted Ags by medullary thymic epithelial cells (mTECs), thereby leading to clonal deletion and Treg-cell production, and ultimately to the establishment of self-tolerance. However, relatively little is known about the mechanism responsible for the control of Aire expression itself. In this issue of the European Journal of Immunology, Haljasorg et al. [Eur. J. Immunol. 2015. 45: 3246-3256] have reported the presence of an enhancer element for Aire that binds with NF-κB components downstream of the TNF receptor family member, RANK (receptor activator of NF-κB). The results suggest that RANK has a dual mode of action in Aire expression: one involving the promotion of mTEC differentiation and the other involving activation of the molecular switch for Aire within mature mTECs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Void formation induced electrical switching in phase-change nanowires.

    Science.gov (United States)

    Meister, Stefan; Schoen, David T; Topinka, Mark A; Minor, Andrew M; Cui, Yi

    2008-12-01

    Solid-state structural transformation coupled with an electronic property change is an important mechanism for nonvolatile information storage technologies, such as phase-change memories. Here we exploit phase-change GeTe single-nanowire devices combined with ex situ and in situ transmission electron microscopy to correlate directly nanoscale structural transformations with electrical switching and discover surprising results. Instead of crystalline-amorphous transformation, the dominant switching mechanism during multiple cycling appears to be the opening and closing of voids in the nanowires due to material migration, which offers a new mechanism for memory. During switching, composition change and the formation of banded structural defects are observed in addition to the expected crystal-amorphous transformation. Our method and results are important to phase-change memories specifically, but also to any device whose operation relies on a small scale structural transformation.

  1. 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.

  2. Role of Al doping in the filament disruption in HfO2 resistance switches

    Science.gov (United States)

    Brivio, Stefano; Frascaroli, Jacopo; Spiga, Sabina

    2017-09-01

    Resistance switching devices, whose operation is driven by formation (SET) and dissolution (RESET) of conductive paths shorting and disconnecting the two metal electrodes, have recently received great attention and a deep general comprehension of their operation has been achieved. However, the link between switching characteristics and material properties is still quite weak. In particular, doping of the switching oxide layer has often been investigated only for looking at performance upgrade and rarely for a meticulous investigation of the switching mechanism. In this paper, the impact of Al doping of HfO2 devices on their switching operations, retention loss mechanisms and random telegraph noise traces is investigated. In addition, phenomenological modeling of the switching operation is performed for device employing both undoped and doped HfO2. We demonstrate that Al doping influences the filament disruption process during the RESET operation and, in particular, it contributes in preventing an efficient restoration of the oxide with respect to undoped devices.

  3. Simulations in generalized ensembles through noninstantaneous switches

    Science.gov (United States)

    Giovannelli, Edoardo; Cardini, Gianni; Chelli, Riccardo

    2015-10-01

    Generalized-ensemble simulations, such as replica exchange and serial generalized-ensemble methods, are powerful simulation tools to enhance sampling of free energy landscapes in systems with high energy barriers. In these methods, sampling is enhanced through instantaneous transitions of replicas, i.e., copies of the system, between different ensembles characterized by some control parameter associated with thermodynamical variables (e.g., temperature or pressure) or collective mechanical variables (e.g., interatomic distances or torsional angles). An interesting evolution of these methodologies has been proposed by replacing the conventional instantaneous (trial) switches of replicas with noninstantaneous switches, realized by varying the control parameter in a finite time and accepting the final replica configuration with a Metropolis-like criterion based on the Crooks nonequilibrium work (CNW) theorem. Here we revise these techniques focusing on their correlation with the CNW theorem in the framework of Markovian processes. An outcome of this report is the derivation of the acceptance probability for noninstantaneous switches in serial generalized-ensemble simulations, where we show that explicit knowledge of the time dependence of the weight factors entering such simulations is not necessary. A generalized relationship of the CNW theorem is also provided in terms of the underlying equilibrium probability distribution at a fixed control parameter. Illustrative calculations on a toy model are performed with serial generalized-ensemble simulations, especially focusing on the different behavior of instantaneous and noninstantaneous replica transition schemes.

  4. Dynamic state switching in nonlinear multiferroic cantilevers

    Science.gov (United States)

    Wang, Yi; Onuta, Tiberiu-Dan; Long, Christian J.; Lofland, Samuel E.; Takeuchi, Ichiro

    2013-03-01

    We demonstrate read-write-read-erase cyclical mechanical-memory properties of all-thin-film multiferroic heterostructured Pb(Zr0.52Ti0.48) O3 / Fe0.7Ga0.3 cantilevers when a high enough voltage around the resonant frequency of the device is applied on the Pb(Zr0.52Ti0.48) O3 piezo-film. The device state switching process occurs due to the presence of a hysteresis loop in the piezo-film frequency response, which comes from the nonlinear behavior of the cantilever. The reference frequency at which the strain-mediated Fe0.7Ga0.3 based multiferroic device switches can also be tuned by applying a DC magnetic field bias that contributes to the increase of the cantilever effective stiffness. The switching dynamics is mapped in the phase space of the device measured transfer function characteristic for such high piezo-film voltage excitation, providing additional information on the dynamical stability of the devices.

  5. Foraging strategy switching in an antlion larva.

    Science.gov (United States)

    Tsao, Yu-Jen; Okuyama, Toshinori

    2012-09-01

    Antlion larvae are typically considered as trap-building predators, but some species of antlions always forage without using pits or only sometimes use pits to capture prey; they can ambush prey without pits. This study examined a species that switches its strategy between pit-trapping and ambushing and asked the mechanism behind the switching behaviour. A dynamic optimization model incorporating tradeoffs between the two strategies was built. The tradeoffs were prey capture success and predation risk (both are higher when pit-trapping). The model predicted that antlions should use the trap-building strategy when their energy status is low and should use the ambush strategy when their energy status is high. These predictions as well as an assumption (i.e., predation risk associated with pit-trapping is higher than that associated with ambushing) of the model were empirically confirmed. The results suggest that antlions flexibly switch between pit-trapping and ambushing to maximize their fitness by balancing the costs and benefits of the two strategies. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Colloidal Switches by Electric and Magnetic Fields.

    Science.gov (United States)

    Demirörs, Ahmet Faik; Beltramo, Peter J; Vutukuri, Hanumantha Rao

    2017-05-24

    External electric and magnetic fields have already been proven to be a versatile tool to control the particle assembly; however, the degree of control of the dynamics and versatility of the produced structures is expected to increase if both can be implemented simultaneously. For example, while micromagnets can rapidly assemble superparamagnetic particles, repeated, rapid disassembly or reassembly is not trivial because of the remanence and coercivity of metals used in such applications. Here, an interdigitated design of micromagnet and microfabricated electrodes enables rapid switching of colloids between their magnetic and electric potential minima. Active control over colloids between two such adjacent potential minima enables a fast on/off mechanism, which is potentially important for optical switches or display technologies. Moreover, we demonstrate that the response time of the colloids between these states is on the order of tens of milliseconds, which is tunable by electric field strength. By carefully designing the electrode pattern, our strategy enables the switchable assembly of single particles down to few microns and also hierarchical assemblies containing many particles. Our work on precise dynamic control over the particle position would open new avenues to find potential applications in optical switches and display technologies.

  7. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  8. Wireless Chalcogenide Nanoionic-Based Radio-Frequency Switch

    Science.gov (United States)

    Nessel, James; Miranda, Felix

    2013-01-01

    A new nonvolatile nanoionic switch is powered and controlled through wireless radio-frequency (RF) transmission. A thin layer of chalcogenide glass doped with a metal ion, such as silver, comprises the operational portion of the switch. For the switch to function, an oxidizable electrode is made positive (anode) with respect to an opposing electrode (cathode) when sufficient bias, typically on the order of a few tenths of a volt or more, is applied. This action causes the metal ions to flow toward the cathode through a coordinated hopping mechanism. At the cathode, a reduction reaction occurs to form a metal deposit. This metal deposit creates a conductive path that bridges the gap between electrodes to turn the switch on. Once this conductive path is formed, no further power is required to maintain it. To reverse this process, the metal deposit is made positive with respect to the original oxidizable electrode, causing the dissolution of the metal bridge thereby turning the switch off. Once the metal deposit has been completely dissolved, the process self-terminates. This switching process features the following attributes. It requires very little to change states (i.e., on and off). Furthermore, no power is required to maintain the states; hence, the state of the switch is nonvolatile. Because of these attributes the integration of a rectenna to provide the necessary power and control is unique to this embodiment. A rectenna, or rectifying antenna, generates DC power from an incident RF signal. The low voltages and power required for the nanoionic switch control are easily generated from this system and provide the switch with a novel capability to be operated and powered from an external wireless device. In one realization, an RF signal of a specific frequency can be used to set the switch into an off state, while another frequency can be used to set the switch to an on state. The wireless, miniaturized, and nomoving- part features of this switch make it

  9. Multiple genetic switches spontaneously modulating bacterial mutability

    Directory of Open Access Journals (Sweden)

    Johnston Randal N

    2010-09-01

    Full Text Available Abstract Background All life forms need both high genetic stability to survive as species and a degree of mutability to evolve for adaptation, but little is known about how the organisms balance the two seemingly conflicting aspects of life: genetic stability and mutability. The DNA mismatch repair (MMR system is essential for maintaining genetic stability and defects in MMR lead to high mutability. Evolution is driven by genetic novelty, such as point mutation and lateral gene transfer, both of which require genetic mutability. However, normally a functional MMR system would strongly inhibit such genomic changes. Our previous work indicated that MMR gene allele conversion between functional and non-functional states through copy number changes of small tandem repeats could occur spontaneously via slipped-strand mis-pairing during DNA replication and therefore may play a role of genetic switches to modulate the bacterial mutability at the population level. The open question was: when the conversion from functional to defective MMR is prohibited, will bacteria still be able to evolve by accepting laterally transferred DNA or accumulating mutations? Results To prohibit allele conversion, we "locked" the MMR genes through nucleotide replacements. We then scored changes in bacterial mutability and found that Salmonella strains with MMR locked at the functional state had significantly decreased mutability. To determine the generalizability of this kind of mutability 'switching' among a wider range of bacteria, we examined the distribution of tandem repeats within MMR genes in over 100 bacterial species and found that multiple genetic switches might exist in these bacteria and may spontaneously modulate bacterial mutability during evolution. Conclusions MMR allele conversion through repeats-mediated slipped-strand mis-pairing may function as a spontaneous mechanism to switch between high genetic stability and mutability during bacterial evolution.

  10. 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.

  11. 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

  12. 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.

  13. Electrostatic Switching in Vertically Oriented Nanotubes for Nonvolatile Memory Applications

    Science.gov (United States)

    Kaul, Anupama B.; Khan, Paul; Jennings, Andrew T.; Greer, Julia R.; Megerian, Krikor G.; Allmen, Paul von

    2009-01-01

    We have demonstrated electrostatic switching in vertically oriented nanotubes or nanofibers, where a nanoprobe was used as the actuating electrode inside an SEM. When the nanoprobe was manipulated to be in close proximity to a single tube, switching voltages between 10 V - 40 V were observed, depending on the geometrical parameters. The turn-on transitions appeared to be much sharper than the turn-off transitions which were limited by the tube-to-probe contact resistances. In many cases, stiction forces at these dimensions were dominant, since the tube appeared stuck to the probe even after the voltage returned to 0 V, suggesting that such structures are promising for nonvolatile memory applications. The stiction effects, to some extent, can be adjusted by engineering the switch geometry appropriately. Nanoscale mechanical measurements were also conducted on the tubes using a custom-built anoindentor inside an SEM, from which preliminary material parameters, such as the elastic modulus, were extracted. The mechanical measurements also revealed that the tubes appear to be well adhered to the substrate. The material parameters gathered from the mechanical measurements were then used in developing an electrostatic model of the switch using a commercially available finite-element simulator. The calculated pull-in voltages appeared to be in agreement to the experimentally obtained switching voltages to first order.

  14. 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

  15. Magnonic interferometric switch for multi-valued logic circuits

    Science.gov (United States)

    Balynsky, Michael; Kozhevnikov, Alexander; Khivintsev, Yuri; Bhowmick, Tonmoy; Gutierrez, David; Chiang, Howard; Dudko, Galina; Filimonov, Yuri; Liu, Guanxiong; Jiang, Chenglong; Balandin, Alexander A.; Lake, Roger; Khitun, Alexander

    2017-01-01

    We investigated a possible use of the magnonic interferometric switches in multi-valued logic circuits. The switch is a three-terminal device consisting of two spin channels where input, control, and output signals are spin waves. Signal modulation is achieved via the interference between the source and gate spin waves. We report experimental data on a micrometer scale prototype based on the Y3Fe2(FeO4)3 structure. The output characteristics are measured at different angles of the bias magnetic field. The On/Off ratio of the prototype exceeds 13 dB at room temperature. Experimental data are complemented by the theoretical analysis and the results of micro magnetic simulations showing spin wave propagation in a micrometer size magnetic junction. We also present the results of numerical modeling illustrating the operation of a nanometer-size switch consisting of just 20 spins in the source-drain channel. The utilization of spin wave interference as a switching mechanism makes it possible to build nanometer-scale logic gates, and minimize energy per operation, which is limited only by the noise margin. The utilization of phase in addition to amplitude for information encoding offers an innovative route towards multi-state logic circuits. We describe possible implementation of the three-value logic circuits based on the magnonic interferometric switches. The advantages and shortcomings inherent in interferometric switches are also discussed.

  16. Light-Induced Switching of Tunable Single-Molecule Junctions

    KAUST Repository

    Sendler, Torsten

    2015-04-16

    A major goal of molecular electronics is the development and implementation of devices such as single-molecular switches. Here, measurements are presented that show the controlled in situ switching of diarylethene molecules from their nonconductive to conductive state in contact to gold nanoelectrodes via controlled light irradiation. Both the conductance and the quantum yield for switching of these molecules are within a range making the molecules suitable for actual devices. The conductance of the molecular junctions in the opened and closed states is characterized and the molecular level E 0, which dominates the current transport in the closed state, and its level broadening Γ are identified. The obtained results show a clear light-induced ring forming isomerization of the single-molecule junctions. Electron withdrawing side-groups lead to a reduction of conductance, but do not influence the efficiency of the switching mechanism. Quantum chemical calculations of the light-induced switching processes correlate these observations with the fundamentally different low-lying electronic states of the opened and closed forms and their comparably small modification by electron-withdrawing substituents. This full characterization of a molecular switch operated in a molecular junction is an important step toward the development of real molecular electronics devices.

  17. Resistance switching at the nanometre scale in amorphous carbon

    International Nuclear Information System (INIS)

    Sebastian, Abu; Rossel, Christophe; Pozidis, Haralampos; Eleftheriou, Evangelos; Pauza, Andrew; Shelby, Robert M; RodrIguez, Arantxa Fraile

    2011-01-01

    The electrical transport and resistance switching mechanism in amorphous carbon (a-C) is investigated at the nanoscale. The electrical conduction in a-C thin films is shown to be captured well by a Poole-Frenkel transport model that involves nonisolated traps. Moreover, at high electric fields a field-induced threshold switching phenomenon is observed. The following resistance change is attributed to Joule heating and subsequent localized thermal annealing. We demonstrate that the mechanism is mostly due to clustering of the existing sp 2 sites within the sp 3 matrix. The electrical conduction behaviour, field-induced switching and Joule-heating-induced rearrangement of atomic order resulting in a resistance change are all reminiscent of conventional phase-change memory materials. This suggests the potential of a-C as a similar nonvolatile memory candidate material.

  18. 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…

  19. 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...

  20. 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

  1. Improved Bearingless Switched-Reluctance Motor

    Science.gov (United States)

    Morrison, Carlos R.

    2003-01-01

    The Morrison rotor, named after its inventor, is a hybrid rotor for use in a bearingless switched-reluctance electric motor. The motor is characterized as bearingless in the sense that it does not rely on conventional mechanical bearings: instead, it functions as both a magnetic bearing and a motor. Bearingless switched-reluctance motors are attractive for use in situations in which large variations in temperatures and/or other extreme conditions preclude the use of conventional electric motors and mechanical bearings. In the Morrison motor, as in a prior bearingless switched-reluctance motor, a multipole rotor is simultaneously levitated and rotated. In the prior motor, simultaneous levitation and rotation are achieved by means of two kinds of stator windings: (1) main motor windings and (2) windings that exert levitating forces on a multipole rotor. The multipole geometry is suboptimum for levitation in that it presents a discontinuous surface to the stator pole faces, thereby degrading the vibration-suppression capability of the magnetic bearing. The Morrison rotor simplifies the stator design in that the stator contains only one type of winding. The rotor is a hybrid that includes both (1) a circular lamination stack for levitation and (2) a multipole lamination stack for rotation. A prototype includes six rotor poles and eight stator poles (see figure). During normal operation, two of the four pairs of opposing stator poles (each pair at right angles to the other pair) levitate the rotor. The remaining two pairs of stator poles exert torque on the six-pole rotor lamination stack to produce rotation. The relative lengths of the circular and multipole lamination stacks on the rotor can be chosen to tailor the performance of the motor for a specific application. For a given overall length, increasing the length of the multipole stack relative to the circular stack results in an increase in torque relative to levitation load capacity and stiffness, and vice versa.

  2. Bearingless Switched-Reluctance Motor Improved

    Science.gov (United States)

    Morrison, Carlos R.

    2004-01-01

    The Morrison rotor, named after its inventor, is a hybrid rotor for use in a switched reluctance electric motor. The motor is characterized as bearingless in the sense that it does not rely on conventional mechanical bearings: instead, it functions as both a magnetic bearing and a motor. Bearingless switched-reluctance motors are attractive for use in situations in which large variations in temperatures and/or other extreme conditions preclude the use of conventional electric motors and mechanical bearings. In the Morrison motor, as in prior bearingless switched-reluctance motors, a multipole rotor is simultaneously levitated and rotated. In the prior motors, simultaneous levitation and rotation are achieved by means of two kinds of stator windings: (1) main motor windings and (2) windings that exert levitating forces on a multipole rotor. The multipole geometry is suboptimum for levitation because it presents a discontinuous surface to the stator pole faces, thereby degrading the vibration suppression capability of the magnetic bearing. The Morrison rotor simplifies the stator design in that it contains only one type of winding. The rotor is a hybrid that includes both (1) a circular lamination stack for levitation and (2) a multipole lamination stack for rotation. Simultaneous levitation and rotation at 6000 rpm were achieved with a prototype that included six rotor poles and eight stator poles. During normal operation, two of the four pairs of opposing stator poles (each pair at right angles to the other pair) levitate the rotor. The remaining two pairs of stator poles exert torque on the six-pole rotor lamination stack to produce rotation. The relative length of the circular and multipole lamination stacks on the rotor can be chosen to tailor the performance of the motor for a specific application. For a given overall length, increasing the length of the multipole stack relative to the circular stack results in an increase in torque relative to the levitation

  3. Bipolar resistive switching and charge transport in silicon oxide memristor

    Energy Technology Data Exchange (ETDEWEB)

    Mikhaylov, Alexey N., E-mail: mian@nifti.unn.ru [Lobachevsky State University of Nizhni Novgorod, 23/3 Gagarin Prospect, Nizhni Novgorod 603950 (Russian Federation); Belov, Alexey I.; Guseinov, Davud V.; Korolev, Dmitry S.; Antonov, Ivan N.; Efimovykh, Denis V.; Tikhov, Stanislav V.; Kasatkin, Alexander P.; Gorshkov, Oleg N.; Tetelbaum, David I.; Bobrov, Alexander I.; Malekhonova, Natalia V.; Pavlov, Dmitry A. [Lobachevsky State University of Nizhni Novgorod, 23/3 Gagarin Prospect, Nizhni Novgorod 603950 (Russian Federation); Gryaznov, Evgeny G. [Lobachevsky State University of Nizhni Novgorod, 23/3 Gagarin Prospect, Nizhni Novgorod 603950 (Russian Federation); Sedakov Scientific-Research Institute, GSP-486, Nizhny Novgorod 603950 (Russian Federation); Yatmanov, Alexander P. [Sedakov Scientific-Research Institute, GSP-486, Nizhny Novgorod 603950 (Russian Federation)

    2015-04-15

    Graphical abstract: - Highlights: • Si-based thin-film memristor structure was fabricated by magnetron sputtering. • We study bipolar resistive switching and charge transport mechanisms. • Resistive switching parameters are determined by a balance between redox reactions. - Abstract: Reproducible bipolar resistive switching has been studied in SiO{sub x}-based thin-film memristor structures deposited by magnetron sputtering technique on the TiN/Ti metalized SiO{sub 2}/Si substrates. It is established that, after electroforming, the structure can be switched between the quasi-ohmic low-resistance state related to silicon chains (conducting filaments) and the high-resistance state with semiconductor-like hopping mechanism of charge transport through the defects in silicon oxide. The switching parameters are determined by a balance between the reduction and oxidation processes that, in turn, are driven by the value and polarity of voltage bias, current, temperature and device environment. The results can be used for the development of silicon-based nonvolatile memory and memristive systems as a key component of future electronics.

  4. Center-Shift Method for the Characterization of Dielectric Charging in RF MEMS Capacitive Switches

    NARCIS (Netherlands)

    Herfst, R.W.; Schmitz, Jurriaan

    2008-01-01

    Radio frequency (RF) micro-electro-mechanical systems (MEMS) capacitive switches show great promise for use in wireless communication devices such as mobile phones, but for the successful application of these switches their reliability needs to be demonstrated. One of the main factors that limits

  5. Bistability in a Metabolic Network Underpins the De Novo Evolution of Colony Switching in Pseudomonas fluorescens

    DEFF Research Database (Denmark)

    Gallie, Jenna; Libby, Eric; Bertels, Frederic

    2015-01-01

    Phenotype switching is commonly observed in nature. This prevalence has allowed the elucidation of a number of underlying molecular mechanisms. However, little is known about how phenotypic switches arise and function in their early evolutionary stages. The first opportunity to provide empirical ...

  6. Single-Mask Fabrication of Temperature Triggered MEMS Switch for Cooling Control in SSL System

    NARCIS (Netherlands)

    Wei, J.; Ye, H.; Van Zeijl, H.W.; Sarro, P.M.; Zhang, G.Q.

    2012-01-01

    A micro-electro-mechanical-system (MEMS) based, temperature triggered, switch is developed as a cost-effective solution for smart cooling control of solid-state-lighting systems. The switch (1.0x0.4 mm2) is embedded in a silicon substrate and fabricated with a single-mask 3D micro-machining process.

  7. Rectifying resistance switching behavior of Ag/SBTO/STMO/p+-Si ...

    Indian Academy of Sciences (India)

    21

    As a result, it exhibits a counter-clockwise polarity. The switching mechanisms originating from oxygen vacancy was also observed in the Al/ n-ZnO/p-NiO/ITO memory devices [18]. Figure 5 demonstrates the resistance evolution of the HRS and the LRS of Ag/SBTO/STMO/p+-Si device within 103 successive switching cycles.

  8. Modelling switching-time effects in high-frequency power conditioning networks

    Science.gov (United States)

    Owen, H. A.; Sloane, T. H.; Rimer, B. H.; Wilson, T. G.

    1979-01-01

    Power transistor networks which switch large currents in highly inductive environments are beginning to find application in the hundred kilohertz switching frequency range. Recent developments in the fabrication of metal-oxide-semiconductor field-effect transistors in the power device category have enhanced the movement toward higher switching frequencies. Models for switching devices and of the circuits in which they are imbedded are required to properly characterize the mechanisms responsible for turning on and turning off effects. Easily interpreted results in the form of oscilloscope-like plots assist in understanding the effects of parametric studies using topology oriented computer-aided analysis methods.

  9. Measurement of switching field reduction of single domain particles in a two-dimensional array

    Science.gov (United States)

    Vértesy, G.; Pardavi-Horvath, M.

    2001-12-01

    The mechanism of switching of uniaxial, single domain, single crystalline epitaxial garnet particles on a two-dimensional square array was investigated, and the reason for the wide distribution of switching fields was studied. In spite that the particles were found very uniform, the existence of soft magnetic defects, not connected to visible crystalline or manufacturing defects of the material, was found to be responsible for the broad distribution of the switching field, Hc=280±85 Oe, as measured on a large number of individual particles. Very good quantitative correlation was found between the strength of the these defects and the switching field.

  10. An innovative hybrid insulation switch to enable/disable electrical loads without overvoltages

    Directory of Open Access Journals (Sweden)

    Zajkowski Konrad

    2017-01-01

    Full Text Available This article describes an innovative project for the design of a low voltage switch to enable/disable electrical devices from an AC source, which is characterised by the absence of arc ignition. When powered off, this device is a galvanically separated of the receiver from the power source. The proposed hybrid interaction has two switches: the insulating switch made of mechanical contacts and the current switch made of elements from power electronics. The absence of arc ignition increases the equipment uptime and improves the comfort-powered receiver and equipment located nearby.

  11. 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.

  12. On the transient dynamics of piezoelectric-based, state-switched systems

    Science.gov (United States)

    Lopp, Garrett K.; Kelley, Christopher R.; Kauffman, Jeffrey L.

    2018-01-01

    This letter reports on the induced mechanical transients for piezoelectric-based, state-switching approaches utilizing both experimental tests and a numerical model that more accurately captures the dynamics associated with a switch between stiffness states. Currently, switching models instantaneously dissipate the stored piezoelectric voltage, resulting in a discrete change in effective stiffness states and a discontinuity in the system dynamics during the switching event. The proposed model allows for a rapid but continuous voltage dissipation and the corresponding variation between stiffness states, as one sees in physical implementations. This rapid variation in system stiffness when switching at a point of non-zero strain leads to high-frequency, large-amplitude transients in the system acceleration response. Utilizing a fundamental piezoelectric bimorph, a comparison between the numerical and experimental results reveals that these mechanical transients are much stronger than originally anticipated and masked by measurement hardware limitations, thus highlighting the significance of an appropriate system model governing the switch dynamics. Such a model enables designers to analyze systems that incorporate piezoelectric-based state switching with greater accuracy to ensure that these transients do not degrade the intended performance. Finally, if the switching does create unacceptable transients, controlling the duration of voltage dissipation enables control over the frequency content and peak amplitudes associated with the switch-induced acceleration transients.

  13. An Integrated Model of Cognitive Control in Task Switching

    Science.gov (United States)

    Altmann, Erik M.; Gray, Wayne D.

    2008-01-01

    A model of cognitive control in task switching is developed in which controlled performance depends on the system maintaining access to a code in episodic memory representing the most recently cued task. The main constraint on access to the current task code is proactive interference from old task codes. This interference and the mechanisms that…

  14. Cell state switching factors and dynamical patterning modules ...

    Indian Academy of Sciences (India)

    Prakash

    Plasticity (i.e. stochastic or condition-dependent variability) of developmental outcome in multicellular organisms is due to two principal mechanisms. The first is largely, though not entirely, a function of differential gene expression and is based on the capacity of individual cells to switch between alternative states under ...

  15. 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.

  16. 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.

  17. 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...

  18. 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

  19. Active Molecular Plasmonics: Controlling Plasmon Resonances with Molecular Switches

    KAUST Repository

    Zheng, Yue Bing

    2009-02-11

    A gold nanodisk array, coated with bistable, redox-controllable [2]rotaxane molecules, when exposed to chemical oxidants and reductants, undergoes switching of its plasmonic properties reversibly. By contrast, (i) bare gold nanodisks and (ii) disks coated with a redox-active, but mechanically inert, control compound do not display surface-plasmon-based switching. Along with calculations based on time-dependent density functional theory, these experimental observations suggest that the nanoscale movements within surface-bound “molecular machines” can be used as the active components in plasmonic devices.

  20. PD control for robot manipulators actuated by switched reluctance motors

    Science.gov (United States)

    Hernández-Guzmán, Victor M.; Carrillo-Serrano, Roberto V.; Silva-Ortigoza, Ramón

    2013-03-01

    This article is concerned with position regulation in direct-drive n degrees of freedom rigid robots equipped only with revolute joints when actuated by switched reluctance motors. Our controller represents an extension to this case of a previous work in the literature which was proposed for a single-switched reluctance motor when moving a simple linear mechanical load. We show how to avoid a singularity present in such a previous controller. We also introduce some simplifications since the number of terms to be fedback is smaller. Further, a linear proportional inner electric current loop is included instead of a velocity dependent one.

  1. 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...

  2. 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

  3. A Single Molecule Study of Two Bacteriophage Epigenetic Switches

    Science.gov (United States)

    Wang, Haowei

    Epigenetic switches allow organisms to evolve into different states by activating/repressing different sets of genes without mutations of the underlying DNA sequence. The study of epigenetic switches is very important to understand the mechanism of human development, the origin of cancer, mental illness and fundamental processes such as gene regulation. The coliphage lambda epigenetic switch, which allows switching from lysogeny to lysis, has been studied for more than 50 years as a paradigm, and has recently received renewed attention. Atomic force microscopy (AFM) was used here to show that the lambda repressor oligomerizes on DNA, primarily as a dodecamer, to secure a DNA loop, which is the basis of the lambda switch. This study also provides support for the idea that specifically bound repressor stabilizes adjacent, non-specifically bound repressor molecules, which confers robustness to the switch. 186 is a member of a different coliphage family. One of the major differences between the two coliphage families is that lambda phages can be induced to switch from the lysogenic to the lytic state by UV radiation, but most coliphages of P2 family, to which 186 belongs, cannot. Interaction between coliphage 186 repressor and DNA is characterized by AFM and tethered particle motion (TPM). To expedite analysis of the AFM data, MatLab codes were written to automate the laborious, manual tracing procedures. The programs automatically recognize DNA segments and protein particles in an image, in order to measure the DNA length and position of bound particles as well as their height, diameter and volume. Application of these algorithms greatly improved the efficiency of AFM analysis. It was showed that 186 CI dimers form heptameric wheels, which induce DNA wrapping and different kinds of DNA looping producing various conformations of nucleoprotein complexes. Information about the dynamics of DNA wrapping and looping on 186 CI particles was also obtained by TPM.

  4. Evaluation of the Delivery QoS Characteristics of Gigabit Ethernet Switches

    CERN Document Server

    Beuran, Razvan; Davies, Neil; Dobinson, Robert W

    2004-01-01

    The event selection system for ATLAS is designed to perform real-time image processing on particle collision data equivalent to 2 TB/s. This data is filtered by a multi-level architecture, resulting in 200 GB/s of data analysed by a distributed system consisting of several thousand PCs and switches. As part of our ongoing work on this system, we performed tests on several Gigabit Ethernet switches manufactured by market leaders, using our custom-built test equipment. We analysed the implications of running network devices at, and just beyond, saturation while deploying service differentiation mechanisms. We quantified the quality degradation that traffic flows experienced when passing through switches. We focused on emergent properties in saturation, including fairness and fidelity to expectations. We discuss the ideals for switch behaviour and compare them against the observed behaviour of real implementations of differentiation mechanisms in switches. This creates a generic benchmark, which is independent o...

  5. Torque and Suspension Force in a Bearingless Switched Reluctance Motor

    Science.gov (United States)

    Takemoto, Masatsugu; Chiba, Akira; Akagi, Hirofumi; Fukao, Tadashi

    Bearingless switched reluctance motors, which can control rotor radial positions with magnetic force, have been proposed. The bearingless switched reluctance motors are characterized by integration of switched reluctance motors and magnetic bearings. These motors have two kinds of stator windings composed of motor main windings and suspension windings in the same stator in order to produce suspension force that can realize rotor shaft suspension without mechanical contacts or lubrication. For successful stable operation, accurate theoretical formulae of instantaneous torque and suspension force are necessary to a rotational speed controller and a rotor radial position controller. This paper derives the theoretical formulae of the instantaneous torque and the suspension force from an assumption of simple permeance distribution. This derivation process makes an assumption that fringing fluxes are distributed on elliptical lines. It is shown with experimental results that the derived theoretical formulae are very accurate in terms of practical application.

  6. Phosphorylation: The Molecular Switch of Double-Strand Break Repair

    Directory of Open Access Journals (Sweden)

    K. C. Summers

    2011-01-01

    Full Text Available Repair of double-stranded breaks (DSBs is vital to maintaining genomic stability. In mammalian cells, DSBs are resolved in one of the following complex repair pathways: nonhomologous end-joining (NHEJ, homologous recombination (HR, or the inclusive DNA damage response (DDR. These repair pathways rely on factors that utilize reversible phosphorylation of proteins as molecular switches to regulate DNA repair. Many of these molecular switches overlap and play key roles in multiple pathways. For example, the NHEJ pathway and the DDR both utilize DNA-PK phosphorylation, whereas the HR pathway mediates repair with phosphorylation of RPA2, BRCA1, and BRCA2. Also, the DDR pathway utilizes the kinases ATM and ATR, as well as the phosphorylation of H2AX and MDC1. Together, these molecular switches regulate repair of DSBs by aiding in DSB recognition, pathway initiation, recruitment of repair factors, and the maintenance of repair mechanisms.

  7. Comparison Between Switching and Creativity Among Bilingual and Monolingual Children

    Directory of Open Access Journals (Sweden)

    Rahim Yousefi

    2017-06-01

    Conclusion In accordance with the results of the study, it can be concluded that learning English through educational institutions, and at an advanced level, significantly increases the switching capability in children as well as their scores across the three components of creativity (fluency, flexibility, and elaboration. Therefore, the role of second language acquisition should be highlighted because of its contribution to children's creativity and ability to switch. In general, better performances of children are attributed to the capability of switching languages, specific cognitive mechanisms used in the two systems of languages, their familiarity with a new culture and customs while learning a new language, the intensive training sessions as well as the special atmosphere prevailing in the classes.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Mechanism of rectification and two-type bipolar resistance switching behaviors of Pt /Pb(Zr0.52Ti0.48)O3 /Nb:SrTiO3

    Science.gov (United States)

    Liu, W. W.; Jia, C. H.; Zhang, Q.; Zhang, W. F.

    2015-12-01

    Epitaxial Pb(Zr0.52Ti0.48)O3 (PZT) films have been grown on Nb:SrTiO3 (NSTO) (1 0 0) substrates. The films are a tetragonal perovskite phase with good density and homogeneity. Rectification behavior and two types of bipolar resistance switching (BRS) have been observed in the Pt/PZT/NSTO device. It exhibits rectification below 3 V. According to piezo force microscopy analysis, PZT film has a multidomain structure below 8 V and the device shows abnormal BRS between 3 V and 8 V. When the voltage increases above 8 V, the polarization of the PZT film tends to saturation and it becomes single domain and displays normal BRS behavior. In addition, the device demonstrates good retention and anti-fatigue properties. The transition from abnormal bipolar to normal bipolar behavior caused by ferroelectric polarization can broaden device applications and enable large flexibility in terms of memory architecture.

  16. Selective and genetic constraints on pneumococcal serotype switching.

    Directory of Open Access Journals (Sweden)

    Nicholas J Croucher

    2015-03-01

    Full Text Available Streptococcus pneumoniae isolates typically express one of over 90 immunologically distinguishable polysaccharide capsules (serotypes, which can be classified into "serogroups" based on cross-reactivity with certain antibodies. Pneumococci can alter their serotype through recombinations affecting the capsule polysaccharide synthesis (cps locus. Twenty such "serotype switching" events were fully characterised using a collection of 616 whole genome sequences from systematic surveys of pneumococcal carriage. Eleven of these were within-serogroup switches, representing a highly significant (p < 0.0001 enrichment based on the observed serotype distribution. Whereas the recombinations resulting in between-serogroup switches all spanned the entire cps locus, some of those that caused within-serogroup switches did not. However, higher rates of within-serogroup switching could not be fully explained by either more frequent, shorter recombinations, nor by genetic linkage to genes involved in β-lactam resistance. This suggested the observed pattern was a consequence of selection for preserving serogroup. Phenotyping of strains constructed to express different serotypes in common genetic backgrounds was used to test whether genotypes were physiologically adapted to particular serogroups. These data were consistent with epistatic interactions between the cps locus and the rest of the genome that were specific to serotype, but not serogroup, meaning they were unlikely to account for the observed distribution of capsule types. Exclusion of these genetic and physiological hypotheses suggested future work should focus on alternative mechanisms, such as host immunity spanning multiple serotypes within the same serogroup, which might explain the observed pattern.

  17. Progress in UWB generation with linear silicon switches

    Science.gov (United States)

    Cardwell, Kendall W.; Giorgi, David M.; McIntyre, Iain A.; Solone, Paul J.; Stuurman, K.; Zucker, Oved S. F.

    1993-06-01

    The use of linear photoconductive switches rather than nonlinear switches for the generation of Ultra-Wide-Band (UWB) pulses provides advantages such as jitter-free operation, low losses, and a reduction of the electrical and mechanical stresses in the switch. These advantages lead to the operation of many switches in series and/or parallel, higher average powers and longer lifetimes. Energy Compression Research Corporation (ECR) has demonstrated an advanced UWB source based on light activated silicon switches (LASS). The UWB source consists of a single LASS device mounted on a low impedance (microstrip transmission line and a high fidelity impedance transformer connected to a 50 (Omega) coaxial connection. The voltage was measured at low impedance and 50 (Omega) to verify the efficiency and fidelity of the impedance transformer. After a transformation of 110:1 in impedance, the measurement at the end of the transformer verified that pulse rise-time was less than 100 ps and the overall efficiency was 50%. The system was tested up to 10 kV into 50 (Omega) before connector breakdown limited further increase. Larger powers can be radiated if the transformer is directly connected to the antenna.

  18. Power requirements reducing of FBG based all-optical switching

    Science.gov (United States)

    Scholtz, Ľubomír.; Solanská, Michaela; Ladányi, Libor; Müllerová, Jarmila

    2017-12-01

    Although Fiber Bragg gratings (FBGs) are well known devices, their using as all-optical switching elements has been still examined. Current research is focused on optimization of their properties for their using in future all-optical networks. The main problem are high switching intensities needed for achieving the changes of the transmission state. Over several years switching intensities have been reduced from hundreds of GW/cm2 to tens of MW/cm2 by selecting appropriate gratings and signal parameters or using suitable materials. Two principal nonlinear effects with similar power requirements can result in the bistable transmission/reflection of an input optical pulse. In the self-phase modulation (SPM) regime switching is achieved by the intense probe pulse itself. Using cross-phase modulation (XPM) a strong pump alters the FBG refractive index experienced by a weak probe pulse. As a result of this the detuning of the probe pulse from the center of the photonic band gap occurs. Using of XPM the effect of modulation instability is reduced. Modulation instability which is the main SPM degradation mechanism. We focused on nonlinear FBGs based on chalcogenide glasses which are very often used in various applications. Thanks to high nonlinear parameters chalcogenide glasses are suitable candidates for reducing switching intensities of nonlinear FBGs.

  19. Monolithic, High-Speed Fiber-Optic Switching Array for Lidar, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA SBIR Phase II effort will develop a 1 x 10 prototype non-mechanical fiber optic switch for use with high power lasers. The proposed optical device is a...

  20. 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.

  1. 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

  2. Piezoelectric Energy Harvester for Batteryless Switch Devices

    Science.gov (United States)

    Kim, Min-Soo; Lee, Sung-Chan; Kim, Sin-Woong; Jeong, Soon-Jong; Kim, In-Sung; Song, Jaesung

    2013-10-01

    This study investigated a piezoelectric energy-harvesting system for a mechanical switch device. Piezoelectric ceramics of 0.4Pb(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3 were prepared by using a conventional solid-state reaction method. Li2O, Bi2O3, and CuO additions were used as sintering aids to develop piezoelectric ceramics for low-temperature sintering. Multilayer piezoelectric ceramics with 10×10×3 mm3 sizes and with Ag-Pd inner electrodes were manufactured by using the conventional tape-casting method with the prepared powder. A prototype of a piezoelectric batteryless switch device using the multilayer ceramics was produced. It showed an output peak-to-peak voltage of 3.8 V and an output power per strike of 18 µW. The performance of the device was good enough for practical use.

  3. Controllable resistive switching in Au/Nb:SrTiO3 microscopic Schottky junctions

    Science.gov (United States)

    Wang, Yuhang; Shi, Xiaolan; Zhao, Kehan; Xie, Guanlin; Huang, Siyu; Zhang, Liuwan

    2016-02-01

    The reversible resistive switching effect at oxide interface shows promising applications in information storage and artificial intelligence. However, the microscopic switching mechanism is still elusive due to the difficulty of direct observation of the electrical and chemical behavior at the buried interface, which becomes a major barrier to design reliable, scalable, and reproducible devices. Here we used a gold-coated AFM tip as a removable electrode to investigate the resistive switching effect in a microscopic Au/Nb:SrTiO3 Schottky junction. We found that unlike the inhomogeneous random resistive switching in the macroscopic Schottky junctions, the high and low resistance states can be reversibly switched in a controllable way on the Nb-doped SrTiO3 surface by the conductive tip. The switching between the high and low resistance states in vacuum is accompanied by the reversible shift of the surface Fermi level. We indicate that the transfer of the interface oxygen ion in a double-well potential is responsible for the resistive switching in both macroscopic and microscopic Schottky junctions. Our findings provide a guide to optimize the key performance parameters of a resistive switching device such as operation voltage, switching speed, on/off ratio, and state retention time by proper electrode selection and fabrication strategy.

  4. Multi-polar resistance switching and memory effect in copper phthalocyanine junctions

    International Nuclear Information System (INIS)

    Qiao Shi-Zhu; Kang Shi-Shou; Li Qiang; Zhong Hai; Kang Yun; Yu Shu-Yun; Han Guang-Bing; Yan Shi-Shen; Mei Liang-Mo; Qin Yu-Feng

    2014-01-01

    Copper phthalocyanine junctions, fabricated by magnetron sputtering and evaporating methods, show multi-polar (unipolar and bipolar) resistance switching and the memory effect. The multi-polar resistance switching has not been observed simultaneously in one organic material before. With both electrodes being cobalt, the unipolar resistance switching is universal. The high resistance state is switched to the low resistance state when the bias reaches the set voltage. Generally, the set voltage increases with the thickness of copper phthalocyanine and decreases with increasing dwell time of bias. Moreover, the low resistance state could be switched to the high resistance state by absorbing the phonon energy. The stability of the low resistance state could be tuned by different electrodes. In Au/copper phthalocyanine/Co system, the low resistance state is far more stable, and the bipolar resistance switching is found. Temperature dependence of electrical transport measurements demonstrates that there are no obvious differences in the electrical transport mechanism before and after the resistance switching. They fit quite well with Mott variable range hopping theory. The effect of Al 2 O 3 on the resistance switching is excluded by control experiments. The holes trapping and detrapping in copper phthalocyanine layer are responsible for the resistance switching, and the interfacial effect between electrodes and copper phthalocyanine layer affects the memory effect. (interdisciplinary physics and related areas of science and technology)

  5. Investigating the relationship between media multitasking and processes involved in task-switching.

    Science.gov (United States)

    Alzahabi, Reem; Becker, Mark W; Hambrick, David Z

    2017-11-01

    Although multitasking with media has increased dramatically in recent years (Rideout, Foehr, & Roberts, 2010), the association between media multitasking and cognitive performance is poorly understood. In addition, the literature on the relationship between media multitasking and task-switching, one measure of cognitive control, has produced mixed results (Alzahabi & Becker, 2013; Minear et al., 2013; Ophir, Nass, & Wagner, 2009). Here we use an individual differences approach to investigate the relationship between media multitasking and task-switching performance by first examining the structure of task-switching and identifying the latent factors that contribute to switch costs. Participants performed a series of 3 different task-switching paradigms, each designed to isolate the effects of a specific putative mechanism (e.g., advanced preparation) related to task-switching performance, as well as a series of surveys to measure media multitasking and intelligence. The results suggest that task-switching performance is related to 2 somewhat independent factors, namely an advanced preparation factor and passive decay factor. In addition, multitasking with media was related to a faster ability to prepare for tasks, resulting in faster task-switching performance without a cost to accuracy. Media multitasking and intelligence were both unrelated to passive decay factors. These findings are consistent with a 2-component model of task-switching (Sohn & Anderson, 2001), as well as an automatic/executive framework of cognitive control (Schneider & Shiffrin, 1977). (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  6. Double-tunnel nanoscale switch with a redox mediator: Operational principles and tunneling spectroscopy

    DEFF Research Database (Denmark)

    Kornyshev, AA; Kumetsov, AM; Ulstrup, Jens

    2005-01-01

    A description of the physical mechanism and operation of a navel nanometric electronic switch [D.I. Gittins et al., Nature 2000 408, 67] is presented. New options for controlling the properties of this device are suggested and analyzed.......A description of the physical mechanism and operation of a navel nanometric electronic switch [D.I. Gittins et al., Nature 2000 408, 67] is presented. New options for controlling the properties of this device are suggested and analyzed....

  7. 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. ...

  8. 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.

  9. 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...

  10. 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.

  11. 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

  12. 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 ...

  13. 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...

  14. 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…

  15. Stochastic switching in biology: from genotype to phenotype

    Science.gov (United States)

    Bressloff, Paul C.

    2017-03-01

    There has been a resurgence of interest in non-equilibrium stochastic processes in recent years, driven in part by the observation that the number of molecules (genes, mRNA, proteins) involved in gene expression are often of order 1-1000. This means that deterministic mass-action kinetics tends to break down, and one needs to take into account the discrete, stochastic nature of biochemical reactions. One of the major consequences of molecular noise is the occurrence of stochastic biological switching at both the genotypic and phenotypic levels. For example, individual gene regulatory networks can switch between graded and binary responses, exhibit translational/transcriptional bursting, and support metastability (noise-induced switching between states that are stable in the deterministic limit). If random switching persists at the phenotypic level then this can confer certain advantages to cell populations growing in a changing environment, as exemplified by bacterial persistence in response to antibiotics. Gene expression at the single-cell level can also be regulated by changes in cell density at the population level, a process known as quorum sensing. In contrast to noise-driven phenotypic switching, the switching mechanism in quorum sensing is stimulus-driven and thus noise tends to have a detrimental effect. A common approach to modeling stochastic gene expression is to assume a large but finite system and to approximate the discrete processes by continuous processes using a system-size expansion. However, there is a growing need to have some familiarity with the theory of stochastic processes that goes beyond the standard topics of chemical master equations, the system-size expansion, Langevin equations and the Fokker-Planck equation. Examples include stochastic hybrid systems (piecewise deterministic Markov processes), large deviations and the Wentzel-Kramers-Brillouin (WKB) method, adiabatic reductions, and queuing/renewal theory. The major aim of this

  16. 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.

  17. Limiting Parameters of the Plasma Opening Switch

    International Nuclear Information System (INIS)

    Dolgachev, G. I.; Ushakov, A. G.

    2001-01-01

    Implementing programs for nuclear fusion research and X-ray generation requires the creation of superpower generators based on plasma opening switches (POSs) capable of commutating currents as high as several tens of megaamperes at output voltages of up to 5 MV and higher. The physical mechanisms limiting the POS voltage are investigated. It is shown that, as the generator voltage U g increases, the voltage multiplication factor k = U POS /U g (where U POS is the POS voltage) decreases. An explanation for such a dependence is proposed, and the maximum value of the POS voltage is estimated. A POS design that enables operating in the above current and voltage ranges is considered. The design is based on applying an external magnetic field to the POS interelectrode gap, increasing the initial generator voltage, and decreasing the linear (along the perimeter of the outer electrode) density of the charge passing through the POS during the conduction phase

  18. Current results and trends in platform switching

    Directory of Open Access Journals (Sweden)

    Hadi Salimi

    2011-01-01

    Full Text Available The platform switching (PLS concept was introduced in the literature in 2005. The biological benefits and clinical effectiveness of the PLS technique have been established by several studies. In this article different aspects of PLS concept are discussed. Crestal bone loss, biologic width, and stress distribution in this concept are comprehensively reviewed. In this article the relative published articles from 1990 to 2011 have been evaluated by electronic search. Because of controversial results especially in immediate loading and animal studies, further modified research is needed to establish the mechanism and effect of the PLS technique. Essential changes in studies including using the control group for accurate interpretation of results and long-term observation, particularly through, randomized, prospective, multicenter trials with large numbers of participants, and implants are necessary.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Three-terminal nanoelectromechanical switch based on tungsten nitride—an amorphous metallic material

    KAUST Repository

    Mayet, Abdulilah M.

    2015-12-04

    © 2016 IOP Publishing Ltd. Nanoelectromechanical (NEM) switches inherently have zero off-state leakage current and nearly ideal sub-threshold swing due to their mechanical nature of operation, in contrast to semiconductor switches. A challenge for NEM switches to be practical for low-power digital logic application is their relatively large operation voltage which can result in higher dynamic power consumption. Herein we report a three-terminal laterally actuated NEM switch fabricated with an amorphous metallic material: tungsten nitride (WNx). As-deposited WNx thin films have high Young\\'s modulus (300 GPa) and reasonably high hardness (3 GPa), which are advantageous for high wear resistance. The first prototype WNx switches are demonstrated to operate with relatively low control voltage, down to 0.8 V for an air gap thickness of 150 nm.

  10. Resistive switching in individual ZnO nanorods: delineating the ionic current by photo-stimulation

    Science.gov (United States)

    Bandopadhyay, K.; Prajapati, K. N.; Mitra, J.

    2018-03-01

    Resistive switching in nanostructured metal oxide semiconductors has been broadly understood to originate from the dynamics of its native point defects. Experimental results of switching observed in individual n-ZnO nanorods grown on a p-type polymer is presented along with an empirical model describing the underlying defect dynamics necessary to observe bi-polar switching. Selective photo excitation of electrons into the defect states delineates the incidence and role of an ionic current in the switching behavior. The understanding further extends to the observance of a negative differential resistance regime that is often coincident in such systems. The analysis not only unifies the underlying physics of the two phenomena but also offers further confidence in the proposed mechanism. We conclude by demonstrating that the effective memresistance of such devices is a strong function of the operating bias and identify parameters that optimize switching performance.

  11. Ultra-compact terahertz switch with graphene ring resonators

    International Nuclear Information System (INIS)

    Sun Jian-Zhong; Gao Fei; Zhang Le

    2016-01-01

    We propose and numerically demonstrate a compact terahertz wave switch which is composed of two graphene waveguides and three graphene ring resonators. Changing the bias voltage of the Fermi level in the center graphene ring, the resonant mode can be tuned when the plasmon waves in the waveguides and rings are coupled. We theoretically explain their mechanisms as being due to bias voltage change induced carrier density of graphene modification and the coupling coefficients of graphene plasmon effect after carrier density change, respectively. The mechanism of such a terahertz wave switch is further theoretically analyzed and numerically investigated with the aid of the finite element method. With an appropriate design, the proposed device offers the opportunity to ‘tune’ the terahertz wave ON–OFF with an ultra-fast, high extinction ratio and compact size. This structure has the potential applications in terahertz wave integrated circuits. (paper)

  12. Digital to analog resistive switching transition induced by graphene buffer layer in strontium titanate based devices.

    Science.gov (United States)

    Wan, Tao; Qu, Bo; Du, Haiwei; Lin, Xi; Lin, Qianru; Wang, Da-Wei; Cazorla, Claudio; Li, Sean; Liu, Sidong; Chu, Dewei

    2018-02-15

    Resistive switching behaviour can be classified into digital and analog switching based on its abrupt and gradual resistance change characteristics. Realizing the transition from digital to analog switching in the same device is essential for understanding and controlling the performance of the devices with various switching mechanisms. Here, we investigate the resistive switching in a device made with strontium titanate (SrTiO 3 ) nanoparticles using X-ray diffractometry, scanning electron microscopy, Raman spectroscopy, and direct electrical measurements. It is found that the well-known rupture/formation of Ag filaments is responsible for the digital switching in the device with Ag as the top electrode. To modulate the switching performance, we insert a reduced graphene oxide layer between SrTiO 3 and the bottom FTO electrode owing to its good barrier property for the diffusion of Ag ions and high out-of-plane resistance. In this case, resistive switching is changed from digital to analog as determined by the modulation of interfacial resistance under applied voltage. Based on that controllable resistance, potentiation and depression behaviours are implemented as well. This study opens up new ways for the design of multifunctional devices which are promising for memory and neuromorphic computing applications. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Cognates Facilitate Switches and Then Confusion: Contrasting Effects of Cascade Versus Feedback on Language Selection.

    Science.gov (United States)

    Li, Chuchu; Gollan, Tamar H

    2017-12-28

    The current study investigated the hypothesis that cognates (i.e., translation equivalents that overlap in form, e.g., lemon is limón in Spanish) facilitate language switches. Spanish-English bilinguals were cued to switch languages while repeatedly naming pictures with cognate versus noncognate names in separate (Experiment 1) or mixed (Experiments 2 and 3) blocks. In all 3 experiments, on the first presentation of each picture, cognates elicited significantly smaller switch costs and were produced faster than noncognates only on switch trials. However, cognate switch-facilitation effects were eliminated (Experiment 2) or reversed (i.e., larger switch costs for cognates than noncognates, in Experiment 3) in mixed blocks with the repeated presentation of a stimulus, largely because of the increasingly slower responses for cognates on switch trials. Cognates may facilitate switches because of increased dual-language activation, which is inhibited on nonswitch trials. With repeated presentation of the same pictures, dual-language activation may feed backup to the lexical level, increasing competition for selection. In contrast, when naming pictures in a cognate block, bilinguals may avoid discrimination problems at the lexical level by adaptively focusing less on activation at the phonological level. Cross-language overlap in phonology appears to influence language selection at both the phonological and lexical levels, involving multiple cognitive mechanisms and reflecting both automatic processes and rapid adaptation to contextual variations in the extent of dual-language activation. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  14. Atomic switch: atom/ion movement controlled devices for beyond von-neumann computers.

    Science.gov (United States)

    Hasegawa, Tsuyoshi; Terabe, Kazuya; Tsuruoka, Tohru; Aono, Masakazu

    2012-01-10

    An atomic switch is a nanoionic device that controls the diffusion of metal ions/atoms and their reduction/oxidation processes in the switching operation to form/annihilate a conductive path. Since metal atoms can provide a highly conductive channel even if their cluster size is in the nanometer scale, atomic switches may enable downscaling to smaller than the 11 nm technology node, which is a great challenge for semiconductor devices. Atomic switches also possess novel characteristics, such as high on/off ratios, very low power consumption and non-volatility. The unique operating mechanisms of these devices have enabled the development of various types of atomic switch, such as gap-type and gapless-type two-terminal atomic switches and three-terminal atomic switches. Novel functions, such as selective volatile/nonvolatile, synaptic, memristive, and photo-assisted operations have been demonstrated. Such atomic switch characteristics can not only improve the performance of present-day electronic systems, but also enable development of new types of electronic systems, such as beyond von- Neumann computers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. 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.

  16. Predicting the asymmetric response of a genetic switch to noise.

    Science.gov (United States)

    Ochab-Marcinek, Anna

    2008-09-07

    We present a simple analytical tool which gives an approximate insight into the stationary behavior of nonlinear systems undergoing the influence of a weak and rapid noise from one dominating source, e.g. the kinetic equations describing a genetic switch with the concentration of one substrate fluctuating around a constant mean. The proposed method allows for predicting the asymmetric response of the genetic switch to noise, arising from the noise-induced shift of stationary states. The method has been tested on an example model of the lac operon regulatory network: a reduced Yildirim-Mackey model with fluctuating extracellular lactose concentration. We calculate analytically the shift of the system's stationary states in the presence of noise. The results of the analytical calculation are in excellent agreement with the results of numerical simulation of the noisy system. The simulation results suggest that the structure of the kinetics of the underlying biochemical reactions protects the bistability of the lactose utilization mechanism from environmental fluctuations. We show that, in the consequence of the noise-induced shift of stationary states, the presence of fluctuations stabilizes the behavior of the system in a selective way: Although the extrinsic noise facilitates, to some extent, switching off the lactose metabolism, the same noise prevents it from switching on.

  17. Filament growth and resistive switching in hafnium oxide memristive devices.

    Science.gov (United States)

    Dirkmann, Sven; Kaiser, Jan; Wenger, Christian; Mussenbrock, Thomas

    2018-03-30

    We report on the resistive switching in TiN/Ti/HfO 2 /TiN memristive devices. A resistive switching model for the device is proposed, taking into account important experimental and theoretical findings. The proposed switching model is validated using 2D and 3D kinetic Monte Carlo simulation models. The models are consistently coupled to the electric field and different current transport mechanisms as direct tunneling, trap assisted tunneling (TAT), ohmic transport, and transport through a quantum point contact (QPC) have been considered. We find that the numerical results are in excellent agreement with experimentally obtained data. Important device parameters, which are difficult or impossible to measure in experiments, are calculated. This includes the shape of the conductive filament, width of filament constriction, current density, and temperature distribution. To obtain insights in the operation of the device, consecutive cycles have been simulated. Furthermore, the switching kinetic for the forming and set process for different applied voltages is investigated. Finally, the influence of an annealing process on the filament growth, especially on the filament growth direction, is discussed.

  18. Genes contribute to the switching dynamics of bistable perception.

    Science.gov (United States)

    Shannon, Robert W; Patrick, Christopher J; Jiang, Yi; Bernat, Edward; He, Sheng

    2011-03-09

    Ordinarily, the visual system provides an unambiguous representation of the world. However, at times alternative plausible interpretations of a given stimulus arise, resulting in a dynamic perceptual alternation of the differing interpretations, commonly referred to as bistable or rivalrous perception. Recent research suggests that common neural mechanisms may be involved in the dynamics of very different types of bistable phenomena. Further, evidence has emerged that genetic factors may be involved in determining the rate of switch for at least one form of bistable perception, known as binocular rivalry. The current study evaluated whether genetic factors contribute to the switching dynamics for distinctly different variants of bistable perception in the same participant sample. Switching rates were recorded for MZ and DZ twin participants in two different bistable perception tasks, binocular rivalry and the Necker Cube. Strong concordance in switching rates across both tasks was evident for MZ but not DZ twins, indicating that genetic factors indeed contribute to the dynamics of multiple forms of bistable perception.

  19. Parp3 Negatively Regulates Immunoglobulin Class Switch Recombination

    Science.gov (United States)

    Robert, Isabelle; Gaudot, Léa; Rogier, Mélanie; Heyer, Vincent; Noll, Aurélia; Dantzer, Françoise; Reina-San-Martin, Bernardo

    2015-01-01

    To generate highly specific and adapted immune responses, B cells diversify their antibody repertoire through mechanisms involving the generation of programmed DNA damage. Somatic hypermutation (SHM) and class switch recombination (CSR) are initiated by the recruitment of activation-induced cytidine deaminase (AID) to immunoglobulin loci and by the subsequent generation of DNA lesions, which are differentially processed to mutations during SHM or to double-stranded DNA break intermediates during CSR. The latter activate the DNA damage response and mobilize multiple DNA repair factors, including Parp1 and Parp2, to promote DNA repair and long-range recombination. We examined the contribution of Parp3 in CSR and SHM. We find that deficiency in Parp3 results in enhanced CSR, while SHM remains unaffected. Mechanistically, this is due to increased occupancy of AID at the donor (Sμ) switch region. We also find evidence of increased levels of DNA damage at switch region junctions and a bias towards alternative end joining in the absence of Parp3. We propose that Parp3 plays a CSR-specific role by controlling AID levels at switch regions during CSR. PMID:26000965

  20. Current-induced switching in transport through anisotropic magnetic molecules

    Science.gov (United States)

    Bode, Niels; Arrachea, Liliana; Lozano, Gustavo S.; Nunner, Tamara S.; von Oppen, Felix

    2012-03-01

    Anisotropic single-molecule magnets may be thought of as molecular switches, with possible applications to molecular spintronics. In this paper, we consider current-induced switching in single-molecule junctions containing an anisotropic magnetic molecule. We assume that the carriers interact with the magnetic molecule through the exchange interaction and focus on the regime of high currents in which the molecular spin dynamics is slow compared to the time which the electrons spend on the molecule. In this limit, the molecular spin obeys a nonequilibrium Langevin equation which takes the form of a generalized Landau-Lifshitz-Gilbert equation and which we derive microscopically by means of a nonequilibrium Born-Oppenheimer approximation. We exploit this Langevin equation to identify the relevant switching mechanisms and to derive the current-induced switching rates. As a by-product, we also derive S-matrix expressions for the various torques entering into the Landau-Lifshitz-Gilbert equation which generalize previous expressions in the literature to nonequilibrium situations.

  1. 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.

  2. 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.

  3. 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.

  4. Bilingual Language Switching: Production vs. Recognition.

    Science.gov (United States)

    Mosca, Michela; de Bot, Kees

    2017-01-01

    This study aims at assessing how bilinguals select words in the appropriate language in production and recognition while minimizing interference from the non-appropriate language. Two prominent models are considered which assume that when one language is in use, the other is suppressed. The Inhibitory Control (IC) model suggests that, in both production and recognition, the amount of inhibition on the non-target language is greater for the stronger compared to the weaker language. In contrast, the Bilingual Interactive Activation (BIA) model proposes that, in language recognition, the amount of inhibition on the weaker language is stronger than otherwise. To investigate whether bilingual language production and recognition can be accounted for by a single model of bilingual processing, we tested a group of native speakers of Dutch (L1), advanced speakers of English (L2) in a bilingual recognition and production task. Specifically, language switching costs were measured while participants performed a lexical decision (recognition) and a picture naming (production) task involving language switching. Results suggest that while in language recognition the amount of inhibition applied to the non-appropriate language increases along with its dominance as predicted by the IC model, in production the amount of inhibition applied to the non-relevant language is not related to language dominance, but rather it may be modulated by speakers' unconscious strategies to foster the weaker language. This difference indicates that bilingual language recognition and production might rely on different processing mechanisms and cannot be accounted within one of the existing models of bilingual language processing.

  5. Bilingual Language Switching: Production vs. Recognition

    Science.gov (United States)

    Mosca, Michela; de Bot, Kees

    2017-01-01

    This study aims at assessing how bilinguals select words in the appropriate language in production and recognition while minimizing interference from the non-appropriate language. Two prominent models are considered which assume that when one language is in use, the other is suppressed. The Inhibitory Control (IC) model suggests that, in both production and recognition, the amount of inhibition on the non-target language is greater for the stronger compared to the weaker language. In contrast, the Bilingual Interactive Activation (BIA) model proposes that, in language recognition, the amount of inhibition on the weaker language is stronger than otherwise. To investigate whether bilingual language production and recognition can be accounted for by a single model of bilingual processing, we tested a group of native speakers of Dutch (L1), advanced speakers of English (L2) in a bilingual recognition and production task. Specifically, language switching costs were measured while participants performed a lexical decision (recognition) and a picture naming (production) task involving language switching. Results suggest that while in language recognition the amount of inhibition applied to the non-appropriate language increases along with its dominance as predicted by the IC model, in production the amount of inhibition applied to the non-relevant language is not related to language dominance, but rather it may be modulated by speakers' unconscious strategies to foster the weaker language. This difference indicates that bilingual language recognition and production might rely on different processing mechanisms and cannot be accounted within one of the existing models of bilingual language processing. PMID:28638361

  6. 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.

  7. 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....

  8. 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.

  9. 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.

  10. Electroforming-free resistive switching memory effect in transparent p-type tin monoxide

    KAUST Repository

    Hota, M. K.

    2014-04-14

    We report reproducible low bias bipolar resistive switching behavior in p-type SnO thin film devices without extra electroforming steps. The experimental results show a stable resistance ratio of more than 100 times, switching cycling performance up to 180 cycles, and data retention of more than 103 s. The conduction mechanism varied depending on the applied voltage range and resistance state of the device. The memristive switching is shown to originate from a redox phenomenon at the Al/SnO interface, and subsequent formation/rupture of conducting filaments in the bulk of the SnO layer, likely involving oxygen vacancies and Sn interstitials.

  11. Multi-level switching in TiO x F y film with nanoparticles

    Science.gov (United States)

    Sun, Xiangyu; Wu, Chuangui; Shuai, Yao; Pan, Xinqiang; Luo, Wenbo; You, Tiangui; Du, Nan; Schmidt, Heidemarie

    2017-09-01

    A reliable bipolar resistive switching device was achieved with multi-level switching behavior in fluorine-doped titanium oxide (TiO x F y ) film. Different resistance states can be precisely controlled by different pulse voltages, which reveals the device’s high potential in neuromorphic research. The characteristics of I-V curves in each resistance state were analyzed. Nanoparticles were observed in the TiO x F y film by HR-TEM. The underlying physical mechanisms during resistance switching are discussed and a model of a meshy conducting path is proposed.

  12. Platonic quantum networks as coherence-assisted switches in perfect and imperfect situations

    International Nuclear Information System (INIS)

    Javaherian, C; Twamley, J

    2015-01-01

    The concept of coherence switches with nanoparticle platonic networks is introduced and analysed. The platonic networks store an initially injected excitation for extremely long durations via the formation of dark states. Switching is achieved by the nano-mechanical arrangements of one site or some part of the network to remove the trapping thus leading to a highly efficient transfer to the target which is irreversibly connected to one site. We present coherence switches based on controlling a cubic network both in the absence and presence of environment and manufacturing/topological noise. (paper)

  13. Space-charge-mediated anomalous ferroelectric switching in P(VDF-TrEE) polymer films

    KAUST Repository

    Hu, Weijin

    2014-11-12

    We report on the switching dynamics of P(VDF-TrEE) copolymer devices and the realization of additional substable ferroelectric states via modulation of the coupling between polarizations and space charges. The space-charge-limited current is revealed to be the dominant leakage mechanism in such organic ferroelectric devices, and electrostatic interactions due to space charges lead to the emergence of anomalous ferroelectric loops. The reliable control of ferroelectric switching in P(VDF-TrEE) copolymers opens doors toward engineering advanced organic memories with tailored switching characteristics.

  14. Long-term RF burn-in effects on dielectric charging of MEMS capacitive switches

    KAUST Repository

    Molinero, David G.

    2013-03-01

    This paper experimentally quantified the long-term effects of RF burn-in, in terms of burn-in and recovery times, and found the effects to be semipermanent. Specifically, most of the benefit could be realized after approximately 20 min of RF burn-in, which would then last for several months. Additionally, since similar effects were observed on both real and faux switches, the effects appeared to be of electrical rather than mechanical nature. These encouraging results should facilitate the application of the switches in RF systems, where high RF power could be periodically applied to rejuvenate the switches. © 2001-2011 IEEE.

  15. A cross-stacked plasmonic nanowire network for high-contrast femtosecond optical switching.

    Science.gov (United States)

    Lin, Yuanhai; Zhang, Xinping; Fang, Xiaohui; Liang, Shuyan

    2016-01-21

    We report an ultrafast optical switching device constructed by stacking two layers of gold nanowires into a perpendicularly crossed network, which works at a speed faster than 280 fs with an on/off modulation depth of about 22.4%. The two stacks play different roles in enhancing consistently the optical switching performance due to their different dependence on the polarization of optical electric fields. The cross-plasmon resonance based on the interaction between the perpendicularly stacked gold nanowires and its Fano-coupling with Rayleigh anomaly is the dominant mechanism for such a high-contrast optical switching device.

  16. Multilevel resistive switching in TiO2/Al2O3 bilayers at low temperature

    Science.gov (United States)

    Andreeva, N.; Ivanov, A.; Petrov, A.

    2018-02-01

    We report an approach to design a metal-insulator-metal (MIM) structure exhibiting multilevel resistive switching. Toward this end, two oxide layers (TiO2 and Al2O3) were combined to form a bilayer structure. MIM structures demonstrate stable bipolar switching relative to the resistive state determined by the bias voltage. The resistive state of such bilayer structures can be electrically tuned over seven orders of magnitude. The resistance is determined by the concentration of oxygen vacancies in the active layer of Al2O3. To elucidate a possible mechanism for resistive switching, structural studies and measurements have been made in the temperature range 50-295 K. Resistive switching occurs over the entire temperature range, which assumes the electronic character of the process in the Al2O3 layer. The experimental results indicate that hopping transport with variable-length jumps is the most probable transport mechanism in these MIM structures.

  17. A biomimetic molecular switch at work: coupling photoisomerization dynamics to peptide structural rearrangement.

    Science.gov (United States)

    García-Iriepa, Cristina; Gueye, Moussa; Léonard, Jérémie; Martínez-López, David; Campos, Pedro J; Frutos, Luis Manuel; Sampedro, Diego; Marazzi, Marco

    2016-03-07

    In spite of considerable interest in the design of molecular switches towards photo-controllable (bio)materials, few studies focused on the major influence of the surrounding environment on the switch photoreactivities. We present a combined experimental and computational study of a retinal-like molecular switch linked to a peptide, elucidating the effects on the photoreactivity and on the α-helix secondary structure. Temperature-dependent, femtosecond UV-vis transient absorption spectroscopy and high-level hybrid quantum mechanics/molecular mechanics methods were applied to describe the photoisomerization process and the subsequent peptide rearrangement. It was found that the conformational heterogeneity of the ground state peptide controls the excited state potential energy surface and the thermally activated population decay. Still, a reversible α-helix to α-hairpin conformational change is predicted, paving the way for a fine photocontrol of different secondary structure elements, hence (bio)molecular functions, using retinal-inspired molecular switches.

  18. 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.

  19. 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.

  20. 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 ...

  1. 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...

  2. 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.

  3. 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)

  4. 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

  5. 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.

  6. 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...

  7. 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....

  8. 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....

  9. Comparison of strain generated in bone by "platform-switched" and "non-platform-switched" implants with straight and angulated abutments under vertical and angulated load: A finite element analysis study

    Directory of Open Access Journals (Sweden)

    Susan Paul

    2013-01-01

    Full Text Available Purpose: The aim of this study was to evaluate the microstrain exhibited by bone around immediately loaded, platform-switched, and non-platform-switched implants under vertical and angled loading using a finite element analysis (FEA and also to evaluate whether platform-switched implants evoke a better response than non-platform-switched implants on a mechanical basis. Materials and Methods: Three-dimensional finite element study was undertaken to model and analyze an immediate loaded situation. FEA was chosen for this study since it is useful in determining the stress and strain around the dental implant. Bone responses to vertical and angulated loads on straight and angulated abutments (platform-switched and non-platform-switched abutments were evaluated. Results: Non-platform-switched abutments tend to exhibit a lower tensile stress and compressive stress but higher microstrain value (conducive to higher chance of bone resorption than platform-switched abutments. Ideal bone remodeling values of microstrain (50-3000 μϵ were exhibited by platform-switched straight abutments under vertical load and angled load (with an abutment-implant diameter difference of 1 mm. Conclusion: In spite of the obvious advantages, the practice of immediate loading is limited due to apprehension associated with compromised bone response and a higher rate of bone loss around an immediately loaded implant. The mechanical basis for the concept of "platform switching" in immediately loaded situation is analyzed in this context. The results of this limited investigation indicated that the ideal values of microstrain (50-3000 microstrain can be exhibited by platform switching of dental implants (with an abutment-implant diameter difference of 1 mm and can be considered as a better alternative for prevention of crestal bone loss when compared to non-platform-switched implants.

  10. Agonism/antagonism switching in allosteric ensembles.

    Science.gov (United States)

    Motlagh, Hesam N; Hilser, Vincent J

    2012-03-13

    Ligands for several transcription factors can act as agonists under some conditions and antagonists under others. The structural and molecular bases of such effects are unknown. Previously, we demonstrated how the folding of intrinsically disordered (ID) protein sequences, in particular, and population shifts, in general, could be used to mediate allosteric coupling between different functional domains, a model that has subsequently been validated in several systems. Here it is shown that population redistribution within allosteric systems can be used as a mechanism to tune protein ensembles such that a given ligand can act as both an agonist and an antagonist. Importantly, this mechanism can be robustly encoded in the ensemble, and does not require that the interactions between the ligand and the protein differ when it is acting either as an agonist or an antagonist. Instead, the effect is due to the relative probabilities of states prior to the addition of the ligand. The ensemble view of allostery that is illuminated by these studies suggests that rather than being seen as switches with fixed responses to allosteric activation, ensembles can evolve to be "functionally pluripotent," with the capacity to up or down regulate activity in response to a stimulus. This result not only helps to explain the prevalence of intrinsic disorder in transcription factors and other cell signaling proteins, it provides important insights about the energetic ground rules governing site-to-site communication in all allosteric systems.

  11. Conceptual design of multiple parallel switching controller

    International Nuclear Information System (INIS)

    Ugolini, D.; Yoshikawa, S.; Ozawa, K.

    1996-01-01

    This paper discusses the conceptual design and the development of a preliminary model of a multiple parallel switching (MPS) controller. The introduction of several advanced controllers has widened and improved the control capability of nonlinear dynamical systems. However, it is not possible to uniquely define a controller that always outperforms the others, and, in many situations, the controller providing the best control action depends on the operating conditions and on the intrinsic properties and behavior of the controlled dynamical system. The desire to combine the control action of several controllers with the purpose to continuously attain the best control action has motivated the development of the MPS controller. The MPS controller consists of a number of single controllers acting in parallel and of an artificial intelligence (AI) based selecting mechanism. The AI selecting mechanism analyzes the output of each controller and implements the one providing the best control performance. An inherent property of the MPS controller is the possibility to discard unreliable controllers while still being able to perform the control action. To demonstrate the feasibility and the capability of the MPS controller the simulation of the on-line operation control of a fast breeder reactor (FBR) evaporator is presented. (author)

  12. Bipolar resistive switching behaviours in ZnMn2O4 film deposited on ...

    Indian Academy of Sciences (India)

    The bipolar resistive switching behaviours of the Ag/ZnMn2O4/p+-Si capacitor are investigated. The bipolar resistive switching is reproducible and shows high ON/OFF ratio of > 102 and long retention times of > 105 s. The conduction mechanism of the Ag/ZnMn2O4/p+-Si capacitor in the low-resistance state (LRS) is ohmic ...

  13. Bipolar resistive switching behaviour in Mn 0.03 Zn 0.97 O ...

    Indian Academy of Sciences (India)

    C o n v e r s e l y , t h e r a t i o i n t h e A g / M Z O / L Z M O / p ^+$-Si device began to decrease after 100 successive switching cycles. The LZMO/MZO interface could play an important role in the resistive switching behaviour of the devices. The dominant conduction mechanism of the two devices is charge-trap emission.

  14. Bipolar resistive switching behaviour in Mn0. 03Zn0. 97O ...

    Indian Academy of Sciences (India)

    C o n v e r s e l y , t h e r a t i o i n t h e A g / M Z O / L Z M O / p ^+$-Si device began to decrease after 100 successive switching cycles. The LZMO/MZO interface could play an important role in the resistive switching behaviour of the devices. The dominant conduction mechanism of the two devices is charge-trap emission.

  15. Strategy switching in the stabilization of unstable dynamics.

    Directory of Open Access Journals (Sweden)

    Jacopo Zenzeri

    Full Text Available In order to understand mechanisms of strategy switching in the stabilization of unstable dynamics, this work investigates how human subjects learn to become skilled users of an underactuated bimanual tool in an unstable environment. The tool, which consists of a mass and two hand-held non-linear springs, is affected by a saddle-like force-field. The non-linearity of the springs allows the users to determine size and orientation of the tool stiffness ellipse, by using different patterns of bimanual coordination: minimal stiffness occurs when the two spring terminals are aligned and stiffness size grows by stretching them apart. Tool parameters were set such that minimal stiffness is insufficient to provide stable equilibrium whereas asymptotic stability can be achieved with sufficient stretching, although at the expense of greater effort. As a consequence, tool users have two possible strategies for stabilizing the mass in different regions of the workspace: 1 high stiffness feedforward strategy, aiming at asymptotic stability and 2 low stiffness positional feedback strategy aiming at bounded stability. The tool was simulated by a bimanual haptic robot with direct torque control of the motors. In a previous study we analyzed the behavior of naïve users and we found that they spontaneously clustered into two groups of approximately equal size. In this study we trained subjects to become expert users of both strategies in a discrete reaching task. Then we tested generalization capabilities and mechanism of strategy-switching by means of stabilization tasks which consist of tracking moving targets in the workspace. The uniqueness of the experimental setup is that it addresses the general problem of strategy-switching in an unstable environment, suggesting that complex behaviors cannot be explained in terms of a global optimization criterion but rather require the ability to switch between different sub-optimal mechanisms.

  16. Force-dependent isomerization kinetics of a highly conserved proline switch modulates the mechanosensing region of filamin

    Science.gov (United States)

    Rognoni, Lorenz; Möst, Tobias; Žoldák, Gabriel; Rief, Matthias

    2014-01-01

    Proline switches, controlled by cis–trans isomerization, have emerged as a particularly effective regulatory mechanism in a wide range of biological processes. In this study, we use single-molecule mechanical measurements to develop a full kinetic and energetic description of a highly conserved proline switch in the force-sensing domain 20 of human filamin and how prolyl isomerization modulates the force-sensing mechanism. Proline isomerization toggles domain 20 between two conformations. A stable cis conformation with slow unfolding, favoring the autoinhibited closed conformation of filamin’s force-sensing domain pair 20–21, and a less stable, uninhibited conformation promoted by the trans form. The data provide detailed insight into the folding mechanisms that underpin the functionality of this binary switch and elucidate its remarkable efficiency in modulating force-sensing, thus combining two previously unconnected regulatory mechanisms, proline switches and mechanosensing. PMID:24706888

  17. 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

  18. The stochastic behavior of a molecular switching circuit with feedback

    Directory of Open Access Journals (Sweden)

    Smith Eric

    2007-05-01

    Full Text Available Abstract Background Using a statistical physics approach, we study the stochastic switching behavior of a model circuit of multisite phosphorylation and dephosphorylation with feedback. The circuit consists of a kinase and phosphatase acting on multiple sites of a substrate that, contingent on its modification state, catalyzes its own phosphorylation and, in a symmetric scenario, dephosphorylation. The symmetric case is viewed as a cartoon of conflicting feedback that could result from antagonistic pathways impinging on the state of a shared component. Results Multisite phosphorylation is sufficient for bistable behavior under feedback even when catalysis is linear in substrate concentration, which is the case we consider. We compute the phase diagram, fluctuation spectrum and large-deviation properties related to switch memory within a statistical mechanics framework. Bistability occurs as either a first-order or second-order non-equilibrium phase transition, depending on the network symmetries and the ratio of phosphatase to kinase numbers. In the second-order case, the circuit never leaves the bistable regime upon increasing the number of substrate molecules at constant kinase to phosphatase ratio. Conclusion The number of substrate molecules is a key parameter controlling both the onset of the bistable regime, fluctuation intensity, and the residence time in a switched state. The relevance of the concept of memory depends on the degree of switch symmetry, as memory presupposes information to be remembered, which is highest for equal residence times in the switched states. Reviewers This article was reviewed by Artem Novozhilov (nominated by Eugene Koonin, Sergei Maslov, and Ned Wingreen.

  19. 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...

  20. Resistive switching in TiO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lin

    2011-10-26

    The continuing improved performance of the digital electronic devices requires new memory technologies which should be inexpensively fabricated for higher integration capacity, faster operation, and low power consumption. Resistive random access memory has great potential to become the front runner as the non volatile memory technology. The resistance states stored in such cell can remain for long time and can be read out none-destructively by a very small electrical pulse. In this work the typically two terminal memory cells containing a thin TiO{sub 2} layer are studied. Polycrystalline TiO{sub 2} thin films are deposited with atomic layer deposition and magnetron reactive sputtering processes, which are both physically and electrically characterized. The resistive switching cells are constructed in a metal/TiO{sub 2}/metal structure. Electroforming process initiate the cell from the beginning good insulator to a real memory cell to program the resistive states. Multilevel resistive bipolar switching controlled by current compliance is the common characteristic observed in these cells, which is potentially to be used as so called multi-bit memory cells to improve the memory capacity. With different top electrodes of Pt, Cu, Ag the resistive switching behaviors are studied. The switching behaviors are different depending on the top metal such as the minimum current compliance, the endurance of the programmed resistance states and the morphology change during the switching. The temperature dependence of different resistance states are investigated. A reduction of the activation energy and their possible conduction mechanisms is discussed on the base of the basic current conduction models. It is found that the resistance state transfers from semiconductor to metallic property with the reducing resistances. The calculated temperature coefficients of their metallic states on the Cu/TiO{sub 2}/Pt and Ag/TiO{sub 2}/Pt are very close to the reported literature data

  1. The Wnt Transcriptional Switch: TLE Removal or Inactivation?

    Science.gov (United States)

    Ramakrishnan, Aravinda-Bharathi; Sinha, Abhishek; Fan, Vinson B; Cadigan, Ken M

    2018-02-01

    Many targets of the Wnt/β-catenin signaling pathway are regulated by TCF transcription factors, which play important roles in animal development, stem cell biology, and oncogenesis. TCFs can regulate Wnt targets through a "transcriptional switch," repressing gene expression in unstimulated cells and promoting transcription upon Wnt signaling. However, it is not clear whether this switch mechanism is a general feature of Wnt gene regulation or limited to a subset of Wnt targets. Co-repressors of the TLE family are known to contribute to the repression of Wnt targets in the absence of signaling, but how they are inactivated or displaced by Wnt signaling is poorly understood. In this mini-review, we discuss several recent reports that address the prevalence and molecular mechanisms of the Wnt transcription switch, including the finding of Wnt-dependent ubiquitination/inactivation of TLEs. Together, these findings highlight the growing complexity of the regulation of gene expression by the Wnt pathway. © 2017 WILEY Periodicals, Inc.

  2. 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

  3. Coevolution between positive reciprocity, punishment, and partner switching in repeated interactions.

    Science.gov (United States)

    Wubs, Matthias; Bshary, Redouan; Lehmann, Laurent

    2016-06-15

    Cooperation based on mutual investments can occur between unrelated individuals when they are engaged in repeated interactions. Individuals then need to use a conditional strategy to deter their interaction partners from defecting. Responding to defection such that the future payoff of a defector is reduced relative to cooperating with it is called a partner control mechanism. Three main partner control mechanisms are (i) to switch from cooperation to defection when being defected ('positive reciprocity'), (ii) to actively reduce the payoff of a defecting partner ('punishment'), or (iii) to stop interacting and switch partner ('partner switching'). However, such mechanisms to stabilize cooperation are often studied in isolation from each other. In order to better understand the conditions under which each partner control mechanism tends to be favoured by selection, we here analyse by way of individual-based simulations the coevolution between positive reciprocity, punishment, and partner switching. We show that random interactions in an unstructured population and a high number of rounds increase the likelihood that selection favours partner switching. In contrast, interactions localized in small groups (without genetic structure) increase the likelihood that selection favours punishment and/or positive reciprocity. This study thus highlights the importance of comparing different control mechanisms for cooperation under different conditions. © 2016 The Author(s).

  4. 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.

  5. 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

  6. 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....

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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...

  12. 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

  13. 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.

  14. Arc detector system for extraction switches in LHC CERN

    CERN Document Server

    Dahlerup-Petersen, K; Kuper, E; Ovchar, V; Zverev, S

    2006-01-01

    The opening switches, which will be used in case of quenches or other failures in CERN’s future LHC collider to extract the large amounts of energy stored in the magnetic field of the superconducting chains of main dipoles (8 chains with 1350 MJ each) and main quadrupoles (16 chains with about 24 MJ each) consist of an array of series/parallel connected, electro-mechanical D.C. breakers, specifically designed for this particular application. During the opening process the magnet excitation current is transferred from the cluster of breakers to extraction resistors for rapid de-excitation of the magnet chain. An arc detector has been developed in order to facilitate the determination of the need for maintenance interventions on the switches. The paper describes the arc detector and highlight results from operation of the detector with a LHC pilot extraction...

  15. Controlled spin switching in a metallocene molecular junction.

    Science.gov (United States)

    Ormaza, M; Abufager, P; Verlhac, B; Bachellier, N; Bocquet, M-L; Lorente, N; Limot, L

    2017-12-07

    The active control of a molecular spin represents one of the main challenges in molecular spintronics. Up to now spin manipulation has been achieved through the modification of the molecular structure either by chemical doping or by external stimuli. However, the spin of a molecule adsorbed on a surface depends primarily on the interaction between its localized orbitals and the electronic states of the substrate. Here we change the effective spin of a single molecule by modifying the molecule/metal interface in a controlled way using a low-temperature scanning tunneling microscope. A nickelocene molecule reversibly switches from a spin 1 to 1/2 when varying the electrode-electrode distance from tunnel to contact regime. This switching is experimentally evidenced by inelastic and elastic spin-flip mechanisms observed in reproducible conductance measurements and understood using first principle calculations. Our work demonstrates the active control over the spin state of single molecule devices through interface manipulation.

  16. Within-item strategy switching in arithmetic: a comparative study in children.

    Science.gov (United States)

    Ardiale, Eléonore; Lemaire, Patrick

    2013-01-01

    The present study aimed at determining whether (1) children were able to interrupt a strategy execution to switch and choose another better strategy, and (2) their ability to switch strategy within-item improved with age. Third, fifth, and seventh graders performed a computational estimation task in which they had to provide the better estimates to two-digit addition problems (e.g., 32 + 54) while using the rounding-down (e.g., 30 + 50) or the rounding-up strategy (e.g., 40 + 60). After having executing the cued strategy (e.g., 30 + 50) during 1,000 ms, participants were given the opportunity to switch to another better strategy (e.g., 40 + 60) or to repeat the same strategy (e.g., 30 + 50). The results showed that children switched strategies within items, and were able to switch more often when the addition problems were cued with the poorer strategy (e.g., 40 + 60 for 32 + 54) than when cued with the better strategy (e.g., 30 + 50). As they grew up, children based their decisions to switch strategies more often on whether the 1,000-ms strategy execution concerned the better strategy or strategy difficulty (i.e., the rounding-up strategy). These findings have important implications to further understand mechanisms underlying within-item strategy switching as well as strategic variations in children.

  17. Analog self-powered harvester achieving switching pause control to increase harvested energy

    Science.gov (United States)

    Makihara, Kanjuro; Asahina, Kei

    2017-05-01

    In this paper, we propose a self-powered analog controller circuit to increase the efficiency of electrical energy harvesting from vibrational energy using piezoelectric materials. Although the existing synchronized switch harvesting on inductor (SSHI) method is designed to produce efficient harvesting, its switching operation generates a vibration-suppression effect that reduces the harvested levels of electrical energy. To solve this problem, the authors proposed—in a previous paper—a switching method that takes this vibration-suppression effect into account. This method temporarily pauses the switching operation, allowing the recovery of the mechanical displacement and, therefore, of the piezoelectric voltage. In this paper, we propose a self-powered analog circuit to implement this switching control method. Self-powered vibration harvesting is achieved in this study by attaching a newly designed circuit to an existing analog controller for SSHI. This circuit aims to effectively implement the aforementioned new switching control strategy, where switching is paused in some vibration peaks, in order to allow motion recovery and a consequent increase in the harvested energy. Harvesting experiments performed using the proposed circuit reveal that the proposed method can increase the energy stored in the storage capacitor by a factor of 8.5 relative to the conventional SSHI circuit. This proposed technique is useful to increase the harvested energy especially for piezoelectric systems having large coupling factor.

  18. Within-item strategy switching in arithmetic: a comparative study in children

    Science.gov (United States)

    Ardiale, Eléonore; Lemaire, Patrick

    2013-01-01

    The present study aimed at determining whether (1) children were able to interrupt a strategy execution to switch and choose another better strategy, and (2) their ability to switch strategy within-item improved with age. Third, fifth, and seventh graders performed a computational estimation task in which they had to provide the better estimates to two-digit addition problems (e.g., 32 + 54) while using the rounding-down (e.g., 30 + 50) or the rounding-up strategy (e.g., 40 + 60). After having executing the cued strategy (e.g., 30 + 50) during 1,000 ms, participants were given the opportunity to switch to another better strategy (e.g., 40 + 60) or to repeat the same strategy (e.g., 30 + 50). The results showed that children switched strategies within items, and were able to switch more often when the addition problems were cued with the poorer strategy (e.g., 40 + 60 for 32 + 54) than when cued with the better strategy (e.g., 30 + 50). As they grew up, children based their decisions to switch strategies more often on whether the 1,000-ms strategy execution concerned the better strategy or strategy difficulty (i.e., the rounding-up strategy). These findings have important implications to further understand mechanisms underlying within-item strategy switching as well as strategic variations in children. PMID:24368906

  19. Evidence for thermally assisted threshold switching behavior in nanoscale phase-change memory cells

    Energy Technology Data Exchange (ETDEWEB)

    Le Gallo, Manuel; Athmanathan, Aravinthan; Krebs, Daniel; Sebastian, Abu [IBM Research-Zurich, 8803 Rüschlikon (Switzerland)

    2016-01-14

    In spite of decades of research, the details of electrical transport in phase-change materials are still debated. In particular, the so-called threshold switching phenomenon that allows the current density to increase steeply when a sufficiently high voltage is applied is still not well understood, even though there is wide consensus that threshold switching is solely of electronic origin. However, the high thermal efficiency and fast thermal dynamics associated with nanoscale phase-change memory (PCM) devices motivate us to reassess a thermally assisted threshold switching mechanism, at least in these devices. The time/temperature dependence of the threshold switching voltage and current in doped Ge{sub 2}Sb{sub 2}Te{sub 5} nanoscale PCM cells was measured over 6 decades in time at temperatures ranging from 40 °C to 160 °C. We observe a nearly constant threshold switching power across this wide range of operating conditions. We also measured the transient dynamics associated with threshold switching as a function of the applied voltage. By using a field- and temperature-dependent description of the electrical transport combined with a thermal feedback, quantitative agreement with experimental data of the threshold switching dynamics was obtained using realistic physical parameters.

  20. Mode switching control of dual-evaporator air-conditioning systems

    International Nuclear Information System (INIS)

    Lin, J.-L.; Yeh, T.-J.

    2009-01-01

    Modern air-conditioners incorporate variable-speed compressors and variable-opening expansion valves as the actuators for improving cooling performance and energy efficiency. These actuators have to be properly feedback-controlled; otherwise the systems may exhibit even poorer performance than the conventional machines which use fixed-speed compressors and mechanical expansion valves. Particularly for an air-conditioner with multiple evaporators, there are occasions that the machine is operated in a mode that only selected evaporator(s) is(are) turned on, and switching(s) between modes occurs(occur) during the control process. In this case, one needs to have more carefully designed control and switching strategies to ensure the system performance. In this paper, a framework for mode switching control of the dual-evaporator air-conditioning (DEAC) system is proposed. The framework is basically an integration of a controller and a dynamic compensator. The controller, which possesses the flow-distribution capability and assumes both evaporators are on throughout the control process, is intended to provide nominal performance. While mode switching is achieved by varying the reference settings in the controller, the dynamic compensator is used to improve the transient responses immediately after the switching. Experiments indicate that the proposed framework can achieve satisfactory indoor temperature regulation and provide bumpless switching between different modes of operation.

  1. 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.

  2. 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.

  3. Some studies on the deformation of the membrane in an RF MEMS switch

    NARCIS (Netherlands)

    Ambati, Vijaya Raghav; Asheim, Andreas; van den Berg, Jan Bouwe; van Gennip, Yves; Gerasimov, Tymofiy; Hlod, Andriy; Planqué, Bob; van der Schans, Martin; van der Stelt, Sjors; Vargas Rivera, Michelangelo; Vondenhoff, Erwin; Bokhove, Onno; Hurink, Johann; Meinsma, Gjerrit; Stolk, Chris; Vellekoop, Michel

    2008-01-01

    Radio Frequency (RF) switches of Micro Electro Mechanical Systems (MEMS) are appealing to the mobile industry because of their energy efficiency and ability to accommodate more frequency bands. However, the electromechanical coupling of the electrical circuit to the mechanical components in RF MEMS

  4. 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...

  5. Evolutionary prisoner's dilemma games on the network with punishment and opportunistic partner switching

    Science.gov (United States)

    Takesue, H.

    2018-02-01

    Punishment and partner switching are two well-studied mechanisms that support the evolution of cooperation. Observation of human behaviour suggests that the extent to which punishment is adopted depends on the usage of alternative mechanisms, including partner switching. In this study, we investigate the combined effect of punishment and partner switching in evolutionary prisoner's dilemma games conducted on a network. In the model, agents are located on the network and participate in the prisoner's dilemma games with punishment. In addition, they can opportunistically switch interaction partners to improve their payoff. Our Monte Carlo simulation showed that a large frequency of punishers is required to suppress defectors when the frequency of partner switching is low. In contrast, cooperation is the most abundant strategy when the frequency of partner switching is high regardless of the strength of punishment. Interestingly, cooperators become abundant not because they avoid the cost of inflicting punishment and earn a larger average payoff per game but rather because they have more numerous opportunities to be referred to as a role agent by defectors. Our results imply that the fluidity of social relationships has a profound effect on the adopted strategy in maintaining cooperation.

  6. A 0.2 V Micro-Electromechanical Switch Enabled by a Phase Transition.

    Science.gov (United States)

    Dong, Kaichen; Choe, Hwan Sung; Wang, Xi; Liu, Huili; Saha, Bivas; Ko, Changhyun; Deng, Yang; Tom, Kyle B; Lou, Shuai; Wang, Letian; Grigoropoulos, Costas P; You, Zheng; Yao, Jie; Wu, Junqiao

    2018-02-26

    Micro-electromechanical (MEM) switches, with advantages such as quasi-zero leakage current, emerge as attractive candidates for overcoming the physical limits of complementary metal-oxide semiconductor (CMOS) devices. To practically integrate MEM switches into CMOS circuits, two major challenges must be addressed: sub 1 V operating voltage to match the voltage levels in current circuit systems and being able to deliver at least millions of operating cycles. However, existing sub 1 V mechanical switches are mostly subject to significant body bias and/or limited lifetimes, thus failing to meet both limitations simultaneously. Here 0.2 V MEM switching devices with ≳10 6 safe operating cycles in ambient air are reported, which achieve the lowest operating voltage in mechanical switches without body bias reported to date. The ultralow operating voltage is mainly enabled by the abrupt phase transition of nanolayered vanadium dioxide (VO 2 ) slightly above room temperature. The phase-transition MEM switches open possibilities for sub 1 V hybrid integrated devices/circuits/systems, as well as ultralow power consumption sensors for Internet of Things applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. The combination of positive and negative feedback loops confers exquisite flexibility to biochemical switches

    International Nuclear Information System (INIS)

    Pfeuty, Benjamin; Kaneko, Kunihiko

    2009-01-01

    A wide range of cellular processes require molecular regulatory pathways to convert a graded signal into a discrete response. One prevalent switching mechanism relies on the coexistence of two stable states (bistability) caused by positive feedback regulations. Intriguingly, positive feedback is often supplemented with negative feedback, raising the question of whether and how these two types of feedback can cooperate to control discrete cellular responses. To address this issue, we formulate a canonical model of a protein–protein interaction network and analyze the dynamics of a prototypical two-component circuit. The appropriate combination of negative and positive feedback loops can bring a bistable circuit close to the oscillatory regime. Notably, sharply activated negative feedback can give rise to a bistable regime wherein two stable fixed points coexist and may collide pairwise with two saddle points. This specific type of bistability is found to allow for separate and flexible control of switch-on and switch-off events, for example (i) to combine fast and reversible transitions, (ii) to enable transient switching responses and (iii) to display tunable noise-induced transition rates. Finally, we discuss the relevance of such bistable switching behavior, and the circuit topologies considered, to specific biological processes such as adaptive metabolic responses, stochastic fate decisions and cell-cycle transitions. Taken together, our results suggest an efficient mechanism by which positive and negative feedback loops cooperate to drive the flexible and multifaceted switching behaviors arising in biological systems

  8. Contribution to high voltage matrix switches reliability

    International Nuclear Information System (INIS)

    Lausenaz, Yvan

    2000-01-01

    Nowadays, power electronic equipment requirements are important, concerning performances, quality and reliability. On the other hand, costs have to be reduced in order to satisfy the market rules. To provide cheap, reliability and performances, many standard components with mass production are developed. But the construction of specific products must be considered following these two different points: in one band you can produce specific components, with delay, over-cost problems and eventuality quality and reliability problems, in the other and you can use standard components in a adapted topologies. The CEA of Pierrelatte has adopted this last technique of power electronic conception for the development of these high voltage pulsed power converters. The technique consists in using standard components and to associate them in series and in parallel. The matrix constitutes high voltage macro-switch where electrical parameters are distributed between the synchronized components. This study deals with the reliability of these structures. It brings up the high reliability aspect of MOSFETs matrix associations. Thanks to several homemade test facilities, we obtained lots of data concerning the components we use. The understanding of defects propagation mechanisms in matrix structures has allowed us to put forwards the necessity of robust drive system, adapted clamping voltage protection, and careful geometrical construction. All these reliability considerations in matrix associations have notably allowed the construction of a new matrix structure regrouping all solutions insuring reliability. Reliable and robust, this product has already reaches the industrial stage. (author) [fr

  9. Impact of deposition parameters on the performance of ceria based resistive switching memories

    International Nuclear Information System (INIS)

    Zhang, Lepeng; Younis, Adnan; Chu, Dewei; Li, Sean

    2016-01-01

    Resistive-switching memories stacked in a metal–insulator–metal (MIM) like structure have shown great potential for next generation non-volatile memories. In this study, ceria based resistive memory stacks are fabricated by implementing different sputter conditions (temperatures and powers). The films deposited at low temperatures were found to have random grain orientations, less porosity and dense structure. The effect of deposition conditions on resistive switching characteristics of as-prepared films were also investigated. Improved and reliable resistive switching behaviors were achieved for the memory devices occupying less porosity and densely packed structures prepared at low temperatures. Finally, the underlying switching mechanism was also explained on the basis of quantitative analysis. (paper)

  10. Analyzing and designing of reliable multicast based on FEC in distributed switch

    Science.gov (United States)

    Luo, Ting; Yu, Shaohua; Wang, Xueshun

    2008-11-01

    AS businesses become more dependent on IP networks, lots of real-time services are adopted and high availability in networks has become increasingly critical. With the development of carrier grade ethernet, the requirements of high speed metro ethernet device are more urgently. In order to reach the capacity of hundreds of Gbps or Tbps, most of core ethernet switches almost adopted distributed control architecture and large capacity forwarding fabric. When distributed switch works, they always have one CE and many FE. There for, it shows the feature of multicast with one sender and many receivers. It is deserved research for us how to apply reliable multicast to distributed switch inner communication system. In this paper, we present the general architecture of a distributed ethernet switch, focusing on analysis the model of internal communication subsystem. According to its character, a novel reliable multicast communication mechanism based on FEC recovery algorithm has been applied and evaluated in experiment.

  11. Switching robust control for ozone generators using the attractive ellipsoid method.

    Science.gov (United States)

    Poznyak, T; Chairez, I; Perez, C; Poznyak, A

    2014-11-01

    This paper deals with a switching robust tracking feedback design for a corona-effect ozone generator. The generator is considered as a switched systems in the presence of bounded model uncertainties as well as external perturbations. Three nonlinear dynamic models under arbitrary switching mechanisms are considered assuming that a sample-switching times are known. The stabilization issue is achieved in the sense of a practical stability. We apply the newly elaborated (extended) version of the conventional attractive ellipsoid method (AEM) for this purpose. The same analysis was efficient to obtain the minimal size of region where the tracking error between the trajectories of the ozone generator and reference states converges. The numerically implementable sufficient conditions for the practical stability of systems are derived based on bilinear matrix inequalities (BMIs). Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  12. Regulating infidelity: RNA-mediated recruitment of AID to DNA during class switch recombination.

    Science.gov (United States)

    DiMenna, Lauren J; Chaudhuri, Jayanta

    2016-03-01

    The mechanism by which the DNA deaminase activation-induced cytidine deaminase (AID) is specifically recruited to repetitive switch region DNA during class switch recombination is still poorly understood. Work over the past decade has revealed a strong link between transcription and RNA polymerase-associated factors in AID recruitment, yet none of these processes satisfactorily explain how AID specificity is affected. Here, we review a recent finding wherein AID is guided to switch regions not by a protein factor but by an RNA moiety, and especially one associated with a noncoding RNA that has been long thought of as being inert. This work explains the long-standing requirement of splicing of noncoding transcripts during class switching, and has implications in both B cell-mediated immunity as well as the underlying pathological syndromes associated with the recombination reaction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Picosecond Electric-Field-Induced Threshold Switching in Phase-Change Materials.

    Science.gov (United States)

    Zalden, Peter; Shu, Michael J; Chen, Frank; Wu, Xiaoxi; Zhu, Yi; Wen, Haidan; Johnston, Scott; Shen, Zhi-Xun; Landreman, Patrick; Brongersma, Mark; Fong, Scott W; Wong, H-S Philip; Sher, Meng-Ju; Jost, Peter; Kaes, Matthias; Salinga, Martin; von Hoegen, Alexander; Wuttig, Matthias; Lindenberg, Aaron M

    2016-08-05

    Many chalcogenide glasses undergo a breakdown in electronic resistance above a critical field strength. Known as threshold switching, this mechanism enables field-induced crystallization in emerging phase-change memory. Purely electronic as well as crystal nucleation assisted models have been employed to explain the electronic breakdown. Here, picosecond electric pulses are used to excite amorphous Ag_{4}In_{3}Sb_{67}Te_{26}. Field-dependent reversible changes in conductivity and pulse-driven crystallization are observed. The present results show that threshold switching can take place within the electric pulse on subpicosecond time scales-faster than crystals can nucleate. This supports purely electronic models of threshold switching and reveals potential applications as an ultrafast electronic switch.

  14. Design and finite element method analysis of laterally actuated multi-value nano electromechanical switches

    KAUST Repository

    Kloub, Hussam

    2011-09-01

    We report on the design and modeling of novel nano electromechanical switches suitable for implementing reset/set flip-flops, AND, NOR, and XNOR Boolean functions. Multiple logic operations can be implemented using only one switching action enabling parallel data processing; a feature that renders this design competitive with complementary metal oxide semiconductor and superior to conventional nano-electromechanical switches in terms of functionality per device footprint. The structural architecture of the newly designed switch consists of a pinned flexural beam structure which allows low strain lateral actuation for enhanced mechanical integrity. Reliable control of on-state electrical current density is achieved through the use of metal-metal contacts, true parallel beam deflection, and lithographically defined contact area to prevent possible device welding. Dynamic response as a function of device dimensions numerically investigated using ANSYS and MatLab Simulink. © 2011 The Japan Society of Applied Physics.

  15. Selective control of multiple ferroelectric switching pathways using a trailing flexoelectric field.

    Science.gov (United States)

    Park, Sung Min; Wang, Bo; Das, Saikat; Chae, Seung Chul; Chung, Jin-Seok; Yoon, Jong-Gul; Chen, Long-Qing; Yang, Sang Mo; Noh, Tae Won

    2018-03-12

    Flexoelectricity is an electromechanical coupling between electrical polarization and a strain gradient 1 that enables mechanical manipulation of polarization without applying an electrical bias 2,3 . Recently, flexoelectricity was directly demonstrated by mechanically switching the out-of-plane polarization of a uniaxial system with a scanning probe microscope tip 3,4 . However, the successful application of flexoelectricity in low-symmetry multiaxial ferroelectrics and therefore active manipulation of multiple domains via flexoelectricity have not yet been achieved. Here, we demonstrate that the symmetry-breaking flexoelectricity offers a powerful route for the selective control of multiple domain switching pathways in multiaxial ferroelectric materials. Specifically, we use a trailing flexoelectric field that is created by the motion of a mechanically loaded scanning probe microscope tip. By controlling the SPM scan direction, we can deterministically select either stable 71° ferroelastic switching or 180° ferroelectric switching in a multiferroic magnetoelectric BiFeO 3 thin film. Phase-field simulations reveal that the amplified in-plane trailing flexoelectric field is essential for this domain engineering. Moreover, we show that mechanically switched domains have a good retention property. This work opens a new avenue for the deterministic selection of nanoscale ferroelectric domains in low-symmetry materials for non-volatile magnetoelectric devices and multilevel data storage.

  16. 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.

  17. Switching profiles in a population-based cohort of rheumatoid arthritis receiving biologic therapy: results from the KOBIO registry.

    Science.gov (United States)

    Park, Dong-Jin; Choi, Sung Jae; Shin, Kichul; Kim, Hyoun-Ah; Park, Yong-Beom; Kang, Seong Wook; Kwok, Seung-Ki; Kim, Seong-Kyu; Nam, Eon Jeong; Sung, Yoon-Kyoung; Lee, Jaejoon; Lee, Chang Hoon; Jeon, Chan Hong; Lee, Shin-Seok

    2017-05-01

    Despite improved quality of care for rheumatoid arthritis (RA) patients, many still experience treatment failure with a biologic agent and eventually switch to another biologic agent. We investigated patterns of biologic treatment and reasons for switching biologics in patients with RA. Patients with RA who had started on a biologic agent or had switched to another biologic agent were identified from the prospective observational Korean nationwide Biologics (KOBIO) registry. The KOBIO registry contained 1184 patients with RA at the time of initiation or switching of biologic agents. Patients were categorized according to the chronological order of the introduction of biologic agents, and reasons for switching biologics were also evaluated. Of the 1184 patients with RA, 801 started with their first biologic agent, 228 were first-time switchers, and 89 were second-time or more switchers. Second-time or more switchers had lower rheumatoid factor and anti-CCP positivity, and higher disease activity scores at the time of enrollment than the other groups. Among these patients, tocilizumab was the most commonly prescribed biologic agent, followed by adalimumab and etanercept. The most common reason for switching biologics was inefficacy, followed by adverse events, including infusion reactions, infections, and skin eruptions. Furthermore, the proportion of inefficacy, as a reason for switching, was significantly higher with respect to switching between biologics with different mechanisms of action than between biologics with similar mechanisms. In this registry, we showed diverse prescribing patterns and differing baseline profiles based on the chronological order of biologic agents.

  18. Highly flexible resistive switching memory based on amorphous-nanocrystalline hafnium oxide films.

    Science.gov (United States)

    Shang, Jie; Xue, Wuhong; Ji, Zhenghui; Liu, Gang; Niu, Xuhong; Yi, Xiaohui; Pan, Liang; Zhan, Qingfeng; Xu, Xiao-Hong; Li, Run-Wei

    2017-06-01

    Flexible and transparent resistive switching memories are highly desired for the construction of portable and even wearable electronics. Upon optimization of the microstructure wherein an amorphous-nanocrystalline hafnium oxide thin film is fabricated, an all-oxide based transparent RRAM device with stable resistive switching behavior that can withstand a mechanical tensile stress of up to 2.12% is obtained. It is demonstrated that the superior electrical, thermal and mechanical performance of the ITO/HfO x /ITO device can be ascribed to the formation of pseudo-straight metallic hafnium conductive filaments in the switching layer, and is only limited by the choice of electrode materials. When the ITO bottom electrode is replaced with platinum metal, the mechanical failure threshold of the device can be further extended.

  19. 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.

  20. Length Scale of Leidenfrost Ratchet Switches Droplet Directionality

    Energy Technology Data Exchange (ETDEWEB)

    Agapov, Rebecca L [ORNL; Boreyko, Jonathan B [ORNL; Briggs, Dayrl P [ORNL; Srijanto, Bernadeta R [ORNL; Retterer, Scott T [ORNL; Collier, Pat [ORNL; Lavrik, Nickolay V [ORNL

    2014-01-01

    Arrays of tilted pillars with characteristic heights spanning from hundreds of nanometers to tens of micrometers were created using wafer level processing and used as Leidenfrost ratchets to control droplet directionality. Dynamic Leidenfrost droplets on the ratchets with nanoscale features were found to move in the direction of the pillar tilt while the opposite directionality was observed on the microscale ratchets. This remarkable switch in the droplet directionality can be explained by varying contributions from the two distinct mechanisms controlling droplet motion on Leidenfrost ratchets with nanoscale and microscale features. In particular, asymmetric wettability of dynamic Leidenfrost droplets upon initial impact appears to be the dominant mechanism determining their directionality on tilted nanoscale pillar arrays. By contrast, asymmetric wetting does not provide a strong enough driving force compared to the forces induced by asymmetric vapour flow on arrays of much taller tilted microscale pillars. Furthermore, asymmetric wetting plays a role only in the dynamic Leidenfrost regime, for instance when droplets repeatedly jump after their initial impact. The point of crossover between the two mechanisms coincides with the pillar heights comparable to the values of the thinnest vapor layers still capable of cushioning Leidenfrost droplets upon their initial impact. The proposed model of the length scale dependent interplay between the two mechanisms points to the previously unexplored ability to bias movement of dynamic Leidenfrost droplets and even switch their directionality.

  1. Length scale of Leidenfrost ratchet switches droplet directionality.

    Science.gov (United States)

    Agapov, Rebecca L; Boreyko, Jonathan B; Briggs, Dayrl P; Srijanto, Bernadeta R; Retterer, Scott T; Collier, C Patrick; Lavrik, Nickolay V

    2014-08-07

    Arrays of tilted pillars with characteristic heights spanning from hundreds of nanometers to tens of micrometers were created using wafer level processing and used as Leidenfrost ratchets to control droplet directionality. Dynamic Leidenfrost droplets on the ratchets with nanoscale features were found to move in the direction of the pillar tilt while the opposite directionality was observed on the microscale ratchets. This remarkable switch in the droplet directionality can be explained by varying contributions from the two distinct mechanisms controlling droplet motion on Leidenfrost ratchets with nanoscale and microscale features. In particular, asymmetric wettability of dynamic Leidenfrost droplets upon initial impact appears to be the dominant mechanism determining their directionality on tilted nanoscale pillar arrays. By contrast, asymmetric wetting does not provide a strong enough driving force compared to the forces induced by asymmetric vapour flow on arrays of much taller tilted microscale pillars. Furthermore, asymmetric wetting plays a role only in the dynamic Leidenfrost regime, for instance when droplets repeatedly jump after their initial impact. The point of crossover between the two mechanisms coincides with the pillar heights comparable to the values of the thinnest vapor layers still capable of cushioning Leidenfrost droplets upon their initial impact. The proposed model of the length scale dependent interplay between the two mechanisms points to the previously unexplored ability to bias movement of dynamic Leidenfrost droplets and even switch their directionality.

  2. 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

  3. 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.

  4. 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.  

  5. 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....

  6. Design of a switched reluctance generator

    Energy Technology Data Exchange (ETDEWEB)

    Heese, T.; Pyrhoenen, J.

    1996-12-31

    This report presents the design of a low voltage switched reluctance generator for variable speed applications showing the design of its construction and commutation unit. For the realisation of the control system the control strategy is presented. The principle and the theory of switched reluctance generators are described in this context. Also an overview of existing generator technology for these applications is given. The results gained suggest that switched reluctance machines can also advantageously be used as generators if the generating operation is considered within the design process. Compared with the existing technology a higher output power and efficiency is reached over the whole speed range. (orig.)

  7. Electrically switched cesium ion exchange

    International Nuclear Information System (INIS)

    Lilga, M.A.; Orth, R.J.; Sukamto, J.P.H.; Schwartz, D.T.; Haight, S.M.; Genders, J.D.

    1997-04-01

    Electrically Switched Ion Exchange (ESIX) is a separation technology being developed as an alternative to conventional ion exchange for removing radionuclides from high-level waste. The ESIX technology, which combines ion exchange and electrochemistry, is geared toward producing electroactive films that are highly selective, regenerable, and long lasting. During the process, ion uptake and elution are controlled directly by modulating the potential of an ion exchange film that has been electrochemically deposited onto a high surface area electrode. This method adds little sodium to the waste stream and minimizes the secondary wastes associated with traditional ion exchange techniques. Development of the ESIX process is well underway for cesium removal using ferrocyanides as the electroactive films. Films having selectivity for perrhenate (a pertechnetate surrogate) over nitrate also have been deposited and tested. A case study for the KE Basin on the Hanford Site was conducted based on the results of the development testing. Engineering design baseline parameters for film deposition, film regeneration, cesium loading, and cesium elution were used for developing a conceptual system. Order of magnitude cost estimates were developed to compare with conventional ion exchange. This case study demonstrated that KE Basin wastewater could be processed continuously with minimal secondary waste and reduced associated disposal costs, as well as lower capital and labor expenditures

  8. Fast equilibrium switch of a micro mechanical oscillator

    Science.gov (United States)

    Le Cunuder, Anne; Martínez, Ignacio A.; Petrosyan, Artyom; Guéry-Odelin, David; Trizac, Emmanuel; Ciliberto, Sergio

    2016-09-01

    We demonstrate an accurate method to control the motion of a micromechanical oscillator in contact with a thermal bath. The experiment is carried out on the cantilever tip of an atomic force microscope. Applying an appropriate time dependent external force, we decrease the time necessary to reach equilibrium by two orders of magnitude compared to the intrinsic equilibration time. Finally, we analyze the energetic cost of such a fast equilibration, by measuring with kB T accuracy the energy exchanges along the process.

  9. Heparan sulfate regulates ADAM12 through a molecular switch mechanism

    DEFF Research Database (Denmark)

    Sørensen, Hans P; Vives, Romain R; Manetopoulos, Christina

    2008-01-01

    The disintegrin and metalloproteases (ADAMs) are emerging as therapeutic targets in human disease, but specific drug design is hampered by potential redundancy. Unlike other metzincins, ADAM pro domains remain bound to the mature enzyme to regulate activity. Here ADAM12, a protease that promotes....... These data present a novel concept that might allow targeting of ADAM12 and suggest that other ADAMs may have specific regulatory activity embedded in their pro and catalytic domain structures....

  10. Friendship-based partner switching promotes cooperation in heterogeneous populations

    Science.gov (United States)

    Chen, Wei; Wu, Te; Li, Zhiwu; Wang, Long

    2016-02-01

    The forming of human social ties tends to be with similar individuals. This study concentrates on the emergence of cooperation among heterogeneous populations. A simple model is proposed by considering the impact of interplay between the evolution of strategies and that of social partnerships on cooperation dynamics. Whenever two individuals acquire the rewards by playing prisoner's dilemma game with each other, the friendship (friendship is quantified as the weight of a link) between the two individuals deepens. Individuals can switch off the social ties with the partners who are unfriendly and rewire to similar new ones. Under this partner switching mechanism, population structure is divided into several groups and cooperation can prevail. It is observed that the frequent tendency of partner switching can lead to the enhancement of cooperative behavior under the enormous temptation to defect. Moreover, the influence of discounting the relationship between different individuals is also investigated. Meanwhile, the cooperation prevails when the adjustment of friendships mainly depends on the incomes of selected individuals rather than that of their partners. Finally, it is found that too similar population fail to maximize the cooperation and there exists a moderate similarity that can optimize cooperation.

  11. Bistable switches control memory and plasticity in cellular differentiation

    Science.gov (United States)

    Wang, Lei; Walker, Brandon L.; Iannaccone, Stephen; Bhatt, Devang; Kennedy, Patrick J.; Tse, William T.

    2009-01-01

    Development of stem and progenitor cells into specialized tissues in multicellular organisms involves a series of cell fate decisions. Cellular differentiation in higher organisms is generally considered irreversible, and the idea of developmental plasticity in postnatal tissues is controversial. Here, we show that inhibition of mitogen-activated protein kinase (MAPK) in a human bone marrow stromal cell-derived myogenic subclone suppresses their myogenic ability and converts them into satellite cell-like precursors that respond to osteogenic stimulation. Clonal analysis of the induced osteogenic response reveals ultrasensitivity and an “all-or-none” behavior, hallmarks of a bistable switch mechanism with stochastic noise. The response demonstrates cellular memory, which is contingent on the accumulation of an intracellular factor and can be erased by factor dilution through cell divisions or inhibition of protein synthesis. The effect of MAPK inhibition also exhibits memory and appears to be controlled by another bistable switch further upstream that determines cell fate. Once the memory associated with osteogenic differentiation is erased, the cells regain their myogenic ability. These results support a model of cell fate decision in which a network of bistable switches controls inducible production of lineage-specific differentiation factors. A competitive balance between these factors determines cell fate. Our work underscores the dynamic nature of cellular differentiation and explains mechanistically the dual properties of stability and plasticity associated with the process. PMID:19366677

  12. Magnetization switching schemes for nanoscale three-terminal spintronics devices

    Science.gov (United States)

    Fukami, Shunsuke; Ohno, Hideo

    2017-08-01

    Utilizing spintronics-based nonvolatile memories in integrated circuits offers a promising approach to realize ultralow-power and high-performance electronics. While two-terminal devices with spin-transfer torque switching have been extensively developed nowadays, there has been a growing interest in devices with a three-terminal structure. Of primary importance for applications is the efficient manipulation of magnetization, corresponding to information writing, in nanoscale devices. Here we review the studies of current-induced domain wall motion and spin-orbit torque-induced switching, which can be applied to the write operation of nanoscale three-terminal spintronics devices. For domain wall motion, the size dependence of device properties down to less than 20 nm will be shown and the underlying mechanism behind the results will be discussed. For spin-orbit torque-induced switching, factors governing the threshold current density and strategies to reduce it will be discussed. A proof-of-concept demonstration of artificial intelligence using an analog spin-orbit torque device will also be reviewed.

  13. Graphene and its derivatives: switching ON and OFF.

    Science.gov (United States)

    Chen, Yu; Zhang, Bin; Liu, Gang; Zhuang, Xiaodong; Kang, En-Tang

    2012-07-07

    As the thinnest material ever known in the universe, graphene has been attracting tremendous amount of attention in both materials science and condensed-matter physics since its successful isolation a few years ago. This one-atom-thick two-dimensional pseudo-infinite nano-crystal consists of sp(2)-hybridized aromatic carbon atoms covalently packed into a continuous hexagonal lattice. Graphene exhibits a range of unique properties, viz., high three-dimensional aspect ratio and large specific surface area, superior mechanical stiffness and flexibility, remarkable optical transmittance, extraordinary thermal response and excellent electronic transport properties, promising its applications in the next generation electronics. To switch graphene and its derivatives between ON and OFF states in nanoelectronic memory devices, various techniques have been developed to manipulate the carbon atomic sheets via introducing the valence-conduction bandgap and to enhance their processability. In this article, we review the utilization of electrically, thermally and chemically modified graphene and its polymer-functionalized derivatives for switching and information storage applications. The challenges posed on the development of novel graphene materials and further enhancements of the device switching performance have also been discussed.

  14. Switching Adaptability in Human-Inspired Sidesteps: A Minimal Model

    Directory of Open Access Journals (Sweden)

    Keisuke Fujii

    2017-06-01

    Full Text Available Humans can adapt to abruptly changing situations by coordinating redundant components, even in bipedality. Conventional adaptability has been reproduced by various computational approaches, such as optimal control, neural oscillator, and reinforcement learning; however, the adaptability in bipedal locomotion necessary for biological and social activities, such as unpredicted direction change in chase-and-escape, is unknown due to the dynamically unstable multi-link closed-loop system. Here we propose a switching adaptation model for performing bipedal locomotion by improving autonomous distributed control, where autonomous actuators interact without central control and switch the roles for propulsion, balancing, and leg swing. Our switching mobility model achieved direction change at any time using only three actuators, although it showed higher motor costs than comparable models without direction change. Our method of evaluating such adaptation at any time should be utilized as a prerequisite for understanding universal motor control. The proposed algorithm may simply explain and predict the adaptation mechanism in human bipedality to coordinate the actuator functions within and between limbs.

  15. Information Switching Processor (ISP) contention analysis and control

    Science.gov (United States)

    Inukai, Thomas

    1995-01-01

    In designing a satellite system with on-board processing, the selection of a switching architecture is often critical. The on-board switching function can be implemented by circuit switching or packet switching. Destination-directed packet switching has several attractive features, such as self-routing without on-board switch reconfiguration, no switch control memory requirement, efficient bandwidth utilization for packet switched traffic, and accommodation of circuit switched traffic. Destination-directed packet switching, however, has two potential concerns: (1) contention and (2) congestion. And this report specifically deals with the first problem. It includes a description and analysis of various self-routing switch structures, the nature of contention problems, and contention and resolution techniques.

  16. Binomial tree method for pricing a regime-switching volatility stock loans

    Science.gov (United States)

    Putri, Endah R. M.; Zamani, Muhammad S.; Utomo, Daryono B.

    2018-03-01

    Binomial model with regime switching may represents the price of stock loan which follows the stochastic process. Stock loan is one of alternative that appeal investors to get the liquidity without selling the stock. The stock loan mechanism resembles that of American call option when someone can exercise any time during the contract period. From the resembles both of mechanism, determination price of stock loan can be interpreted from the model of American call option. The simulation result shows the behavior of the price of stock loan under a regime-switching with respect to various interest rate and maturity.

  17. Robust dynamic output feedback control for switched polytopic systems under asynchronous switching

    Directory of Open Access Journals (Sweden)

    Yang Tingting

    2015-08-01

    Full Text Available The robust controller design problem for switched polytopic systems under asynchronous switching is addressed. These systems exist in many aviation applications, such as dynamical systems involving rapid variations. A switched polytopic system is established to describe the highly maneuverable technology vehicle within the full flight envelope and a robust dynamic output feedback control method is designed for the switched polytopic system. Combining the Lyapunov-like function method and the average dwell time method, a sufficient condition is derived for the switched polytopic system with asynchronous switching and data dropout to be globally, uniformly and asymptotically stable in terms of linear matrix inequality. The robust dynamic output feedback controller is then applied to the highly maneuverable technology vehicle to illustrate the effectiveness of the proposed approach. The simulation results show that the angle of attack tracking performance is acceptable over the time history and the control surface responses are all satisfying along the full flight trajectory.

  18. Instability in time-delayed switched systems induced by fast and random switching

    Science.gov (United States)

    Guo, Yao; Lin, Wei; Chen, Yuming; Wu, Jianhong

    2017-07-01

    In this paper, we consider a switched system comprising finitely or infinitely many subsystems described by linear time-delayed differential equations and a rule that orchestrates the system switching randomly among these subsystems, where the switching times are also randomly chosen. We first construct a counterintuitive example where even though all the time-delayed subsystems are exponentially stable, the behaviors of the randomly switched system change from stable dynamics to unstable dynamics with a decrease of the dwell time. Then by using the theories of stochastic processes and delay differential equations, we present a general result on when this fast and random switching induced instability should occur and we extend this to the case of nonlinear time-delayed switched systems as well.

  19. Construction of large scale switch matrix by interconnecting integrated optical switch chips with EDFAs

    Science.gov (United States)

    Liao, Mingle; Wu, Baojian; Hou, Jianhong; Qiu, Kun

    2018-03-01

    Large scale optical switches are essential components in optical communication network. We aim to build up a large scale optical switch matrix by the interconnection of silicon-based optical switch chips using 3-stage CLOS structure, where EDFAs are needed to compensate for the insertion loss of the chips. The optical signal-to-noise ratio (OSNR) performance of the resulting large scale optical switch matrix is investigated for TE-mode light and the experimental results are in agreement with the theoretical analysis. We build up a 64 ×64 switch matrix by use of 16 ×16 optical switch chips and the OSNR and receiver sensibility can respectively be improved by 0.6 dB and 0.2 dB by optimizing the gain configuration of the EDFAs.

  20. Dissipation enhanced vibrational sensing in an olfactory molecular switch

    International Nuclear Information System (INIS)

    Chęcińska, Agata; Heaney, Libby; Pollock, Felix A.; Nazir, Ahsan

    2015-01-01

    Motivated by a proposed olfactory mechanism based on a vibrationally activated molecular switch, we study electron transport within a donor-acceptor pair that is coupled to a vibrational mode and embedded in a surrounding environment. We derive a polaron master equation with which we study the dynamics of both the electronic and vibrational degrees of freedom beyond previously employed semiclassical (Marcus-Jortner) rate analyses. We show (i) that in the absence of explicit dissipation of the vibrational mode, the semiclassical approach is generally unable to capture the dynamics predicted by our master equation due to both its assumption of one-way (exponential) electron transfer from donor to acceptor and its neglect of the spectral details of the environment; (ii) that by additionally allowing strong dissipation to act on the odorant vibrational mode, we can recover exponential electron transfer, though typically at a rate that differs from that given by the Marcus-Jortner expression; (iii) that the ability of the molecular switch to discriminate between the presence and absence of the odorant, and its sensitivity to the odorant vibrational frequency, is enhanced significantly in this strong dissipation regime, when compared to the case without mode dissipation; and (iv) that details of the environment absent from previous Marcus-Jortner analyses can also dramatically alter the sensitivity of the molecular switch, in particular, allowing its frequency resolution to be improved. Our results thus demonstrate the constructive role dissipation can play in facilitating sensitive and selective operation in molecular switch devices, as well as the inadequacy of semiclassical rate equations in analysing such behaviour over a wide range of parameters

  1. 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.

  2. Topological photonic orbital-angular-momentum switch

    Science.gov (United States)

    Luo, Xi-Wang; Zhang, Chuanwei; Guo, Guang-Can; Zhou, Zheng-Wei

    2018-04-01

    The large number of available orbital-angular-momentum (OAM) states of photons provides a unique resource for many important applications in quantum information and optical communications. However, conventional OAM switching devices usually rely on precise parameter control and are limited by slow switching rate and low efficiency. Here we propose a robust, fast, and efficient photonic OAM switch device based on a topological process, where photons are adiabatically pumped to a target OAM state on demand. Such topological OAM pumping can be realized through manipulating photons in a few degenerate main cavities and involves only a limited number of optical elements. A large change of OAM at ˜10q can be realized with only q degenerate main cavities and at most 5 q pumping cycles. The topological photonic OAM switch may become a powerful device for broad applications in many different fields and motivate a topological design of conventional optical devices.

  3. Blood and Books: Performing Code Switching

    Directory of Open Access Journals (Sweden)

    Jeff Friedman

    2008-05-01

    Full Text Available Code switching is a linguistic term that identifies ways individuals use communication modes and registers to negotiate difference in social relations. This essay suggests that arts-based inquiry, in the form of choreography and performance, provides a suitable and efficacious location within which both verbal and nonverbal channels of code switching can be investigated. Blood and Books, a case study of dance choreography within the context of post-colonial Maori performance in Aotearoa/New Zealand, is described and analyzed for its performance of code switching. The essay is framed by a discussion of how arts-based research within tertiary higher education requires careful negotiation in the form of code switching, as performed by the author's reflexive use of vernacular and formal registers in the essay. URN: urn:nbn:de:0114-fqs0802462

  4. Active plasmonics in WDM traffic switching applications

    DEFF Research Database (Denmark)

    Papaioannou, S.; Kalavrouziotis, D.; Vyrsokinos, K.

    2012-01-01

    With metal stripes being intrinsic components of plasmonic waveguides, plasmonics provides a "naturally" energy-efficient platform for merging broadband optical links with intelligent electronic processing, instigating a great promise for low-power and small-footprint active functional circuitry....... The first active Dielectric-Loaded Surface Plasmon Polariton (DLSPP) thermo-optic (TO) switches with successful performance in single-channel 10 Gb/s data traffic environments have led the inroad towards bringing low-power active plasmonics in practical traffic applications. In this article, we introduce...... active plasmonics into Wavelength Division Multiplexed (WDM) switching applications, using the smallest TO DLSPP-based Mach-Zehnder interferometric switch reported so far and showing its successful performance in 4310 Gb/s low-power and fast switching operation. The demonstration of the WDM...

  5. Bistable fluidic valve is electrically switched

    Science.gov (United States)

    Fiet, O.; Salvinski, R. J.

    1970-01-01

    Bistable control valve is selectively switched by direct application of an electrical field to divert fluid from one output channel to another. Valve is inexpensive, has no moving parts, and operates on fluids which are relatively poor electrical conductors.

  6. Multi-planed unified switching topologies

    Science.gov (United States)

    Chen, Dong; Heidelberger, Philip; Sugawara, Yutaka

    2017-07-04

    An apparatus and method for extending the scalability and improving the partitionability of networks that contain all-to-all links for transporting packet traffic from a source endpoint to a destination endpoint with low per-endpoint (per-server) cost and a small number of hops. An all-to-all wiring in the baseline topology is decomposed into smaller all-to-all components in which each smaller all-to-all connection is replaced with star topology by using global switches. Stacking multiple copies of the star topology baseline network creates a multi-planed switching topology for transporting packet traffic. Point-to-point unified stacking method using global switch wiring methods connects multiple planes of a baseline topology by using the global switches to create a large network size with a low number of hops, i.e., low network latency. Grouped unified stacking method increases the scalability (network size) of a stacked topology.

  7. Information, switching costs, and consumer choice:

    DEFF Research Database (Denmark)

    Anell, Anders; Dietrichson, Jens; Maria Ellegård, Lina

    . Such improvements are contingent on consumers having access to comparative information about providers and acting on this information when making their choice. However, in the presence of information frictions and switching costs, consumers may have limited ability to find suitable providers. We use two large......-scale randomized eld experiments in primary health care to examine if the choice of provider is affected when consumers receive comparative information by postal mail and small costs associated with switching are reduced. The first experiment targeted a subset of the general population in the Swedish region Skåne......, and the second targeted new residents in the region, who should have less prior information and lower switching costs. In both cases, the propensity to switch provider increased significantly after the intervention. The effects were larger for new residents than for the general population, and were driven...

  8. Analysis of Switched-Rigid Floating Oscillator

    Directory of Open Access Journals (Sweden)

    Prabhakar R. Marur

    2009-01-01

    Full Text Available In explicit finite element simulations, a technique called deformable-to-rigid (D2R switching is used routinely to reduce the computation time. Using the D2R option, the deformable parts in the model can be switched to rigid and reverted back to deformable when needed during the analysis. The time of activation of D2R however influences the overall dynamics of the system being analyzed. In this paper, a theoretical basis for the selection of time of rigid switching based on system energy is established. A floating oscillator problem is investigated for this purpose and closed-form analytical expressions are derived for different phases in rigid switching. The analytical expressions are validated by comparing the theoretical results with numerical computations.

  9. Modeling switching behaviour of direct selling customers

    Directory of Open Access Journals (Sweden)

    P Msweli-Mbanga

    2004-04-01

    Full Text Available The direct selling industry suffers a high turnover rate of salespeople, resulting in high costs of training new salespeople. Further costs are incurred when broken relationships with customers cause them to switch from one product supplier to another. This study identifies twelve factors that drive the switching behaviour of direct sales customers and examines the extent to which these factors influence switching. Exploratory factor analysis was used to assess the validity of these factors. The factors were represented in a model that posits that an interpersonal relationship between a direct sales person and a customer moderates the relationship between switching behaviour and loyalty. Structural equation modeling was used to test the proposed model. The author then discusses the empirical findings and their managerial implications, providing further avenues for research.

  10. What makes the lac-pathway switch: identifying the fluctuations that trigger phenotype switching in gene regulatory systems.

    Science.gov (United States)

    Bhogale, Prasanna M; Sorg, Robin A; Veening, Jan-Willem; Berg, Johannes

    2014-10-01

    Multistable gene regulatory systems sustain different levels of gene expression under identical external conditions. Such multistability is used to encode phenotypic states in processes including nutrient uptake and persistence in bacteria, fate selection in viral infection, cell-cycle control and development. Stochastic switching between different phenotypes can occur as the result of random fluctuations in molecular copy numbers of mRNA and proteins arising in transcription, translation, transport and binding. However, which component of a pathway triggers such a transition is generally not known. By linking single-cell experiments on the lactose-uptake pathway in E. coli to molecular simulations, we devise a general method to pinpoint the particular fluctuation driving phenotype switching and apply this method to the transition between the uninduced and induced states of the lac-genes. We find that the transition to the induced state is not caused only by the single event of lac-repressor unbinding, but depends crucially on the time period over which the repressor remains unbound from the lac-operon. We confirm this notion in strains with a high expression level of the lac-repressor (leading to shorter periods over which the lac-operon remains unbound), which show a reduced switching rate. Our techniques apply to multistable gene regulatory systems in general and allow to identify the molecular mechanisms behind stochastic transitions in gene regulatory circuits. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

  11. Spontaneous class switch recombination in B cell lymphopoiesis generates aberrant switch junctions and is increased after VDJ rearrangement.

    Science.gov (United States)

    Edry, Efrat; Koralov, Sergei B; Rajewsky, Klaus; Melamed, Doron

    2007-11-15

    Mature B cells replace the mu constant region of the H chain with a downstream isotype in a process of class switch recombination (CSR). Studies suggest that CSR induction is limited to activated mature B cells in the periphery. Recently, we have shown that CSR spontaneously occur in B lymphopoiesis. However, the mechanism and regulation of it have not been defined. In this study, we show that spontaneous CSR occurs at all stages of B cell development and generates aberrant joining of the switch junctions as revealed by: 1) increased load of somatic mutations around the CSR break points, 2) reduced sequence overlaps at the junctions, and 3) excessive switch region deletion. In addition, we found that incidence of spontaneous CSR is increased in cells carrying VDJ rearrangements. Our results reveal major differences between spontaneous CSR in developing B cells and CSR induced in mature B cells upon activation. These differences can be explained by deregulated expression or function of activation-induced cytidine deaminase early in B cell development.

  12. Charge trapping-detrapping induced resistive switching in Ba0.7Sr0.3TiO3

    Directory of Open Access Journals (Sweden)

    Xi Zou

    2012-09-01

    Full Text Available Intensive research has been devoted to the resistive switching phenomena observed in many transitional metal oxides because of its potential for non-volatile memory application. To clarify the underlying mechanism of resistive switching, a planar device can provide information that is not accessible in conventional vertical sandwich structures. Here we report the observation of resistive switching behavior in a Pt/Ba0.7Sr0.3TiO3/Pt planar device. Using in-situ scanning Kelvin probe microscopy, we demonstrate that charge trapping/detrapping around the Pt/Ba0.7Sr0.3TiO3 interface modulates the Schottky barrier, resulting in the observed resistive switching. The findings are valuable for the understanding of resistive switching in oxide materials.

  13. Ultra-fast all-optical plasmonic switching in near infra-red spectrum using a Kerr nonlinear ring resonator

    Science.gov (United States)

    Nurmohammadi, Tofiq; Abbasian, Karim; Yadipour, Reza

    2018-03-01

    In this paper, an all-optical plasmonic switch based on metal-insulator-metal (MIM) nanoplasmonic waveguide with a Kerr nonlinear ring resonator is introduced and studied. Two-dimensional simulations utilizing the finite-difference time-domain algorithm are used to demonstrate an apparent optical bistability and significant switching mechanisms (in enabled-low condition: T(ON/OFF) =21.9 and in enabled-high condition: T(ON/OFF) =24.9) of the signal light arisen by altering the pump-light intensity. The proposed all-optical switching demonstrates femtosecond-scale feedback time (90 fs) and then ultra-fast switching can be achieved. The offered all-optical switch may recognize potential significant applications in integrated optical circuits.

  14. The Robustness of Stochastic Switching Networks

    OpenAIRE

    Loh, Po-Ling; Zhou, Hongchao; Bruck, Jehoshua

    2009-01-01

    Many natural systems, including chemical and biological systems, can be modeled using stochastic switching circuits. These circuits consist of stochastic switches, called pswitches, which operate with a fixed probability of being open or closed. We study the effect caused by introducing an error of size ∈ to each pswitch in a stochastic circuit. We analyze two constructions – simple series-parallel and general series-parallel circuits – and prove that simple series-parallel circuits are robus...

  15. Automatic Control System Switching Roadway Lighting

    OpenAIRE

    Agus Trimuji Susilo; Lingga Hermanto Drs. MM

    2002-01-01

    Lack of attention to the information officer street lights, cause is not exactly the timewhen the blame lights street lighting street - the street in this city protocol. And whenit was already dark, the lights had not lit, so it can harm the users of the road. Werecommend that when it got bright lights - the lights switched off late, so muchelectricity is wasted with nothing - nothing.Given the problems above, the automatic switching is required that can control all thelights - the existing l...

  16. Optical waveguide switch through magnetic reflectance wall

    Science.gov (United States)

    Fang, Yuntuan; Ni, Zhiyao; Yang, Lixia

    2016-04-01

    We propose a new design to achieve optical waveguide switch. We construct a photonic crystal waveguide with one yttrium iron garnet (YIG) rod array on the two sides of the waveguide. Through the mode analysis, we find in special frequency range a few YIG rods under magnetic field can form the magnetic reflectance wall that blocks the light flow. Removing the magnetic field will delete the reflection wall and let the blocked light to be switched on.

  17. Ring oscillator switching noise under NBTI wearout

    OpenAIRE

    Fernández García, Raúl; Gil Galí, Ignacio; Ruiz, José María; Morata Cariñena, Marta

    2011-01-01

    In this paper the switching noise of a CMOS ring oscillator has been analysed when their pFETs are subjected to negative bias temperature instability (NBTI). The impact of pFET under NBTI has been experimentally quantified whereas CMOS ring oscillator frequency and the switching noise has been analysed by means of electrical full-model simulation. The results show that the impact on the electromagnetic compatibility behaviour increases with NBTI wearout. Peer Reviewed

  18. Portfolio Selection with Jumps under Regime Switching

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2010-01-01

    Full Text Available We investigate a continuous-time version of the mean-variance portfolio selection model with jumps under regime switching. The portfolio selection is proposed and analyzed for a market consisting of one bank account and multiple stocks. The random regime switching is assumed to be independent of the underlying Brownian motion and jump processes. A Markov chain modulated diffusion formulation is employed to model the problem.

  19. Lasers for switched-power linacs

    International Nuclear Information System (INIS)

    Bigio, I.J.

    1988-01-01

    Laser-switched power surges for particle accelerators, just as with direct laser-driven accelerator schemes, place unique demands on the specifications of the invoked laser systems. We review the laser requirements for switched power sources of the types described in other chapters of this volume. The relative advantages and disadvantages of selected lasers are listed, and the appropriateness and scalability of existing technology is discussed. 4 refs., 2 figs., 2 tabs

  20. New pulse modulator with low switching frequency

    Directory of Open Access Journals (Sweden)

    Golub V. S.

    2014-12-01

    Full Text Available The author presents an integrating pulse modulator (analog signal converter with the pulse frequency and duration modulation similar to sigma-delta modulation (with low switching frequency, without quantization. The modulator is characterized by the absence of the quantization noise inherent in sigma-delta modulator, and a low switching frequency, unlike the pulse-frequency modulator. The modulator is recommended, in particular, to convert signals at the input of the class D power amplifier.

  1. On The Snubber Influence To The Switching And Conduction Losses In A Converter Using Switched Capacitor

    Directory of Open Access Journals (Sweden)

    Viorel DUGAN

    2002-12-01

    Full Text Available The paper deals to design and to compute the snubber parameters influence on the switching and conduction losses of the transistors (IGBT used as bidirectional switches in a converter with switched capacitor. The converter was modelled with difference equations, and the transistors during turn-on and turn-off processes were simulated by dynamically varying resistance models. The energy loss per switching, commutation time, the variation of the transistor voltage etc. and the influence of snubber parameters in each of these cases are shown in the context of a converter used as a 50Hz reactive power controller unit

  2. Research on a novel Rotor Structure Switched Reluctance Motor

    Science.gov (United States)

    Zeng, Lingquan; Yu, Haiwei

    The paper proposes a novel switched reluctance motor with improved rotor structure, in which the segment core is embedded in aluminum rotor block in order to increase the mechanical strength and easy manufacturing as well as to improve the performance characteristics and reduce the vibration and acoustic noise. The effect of design parameters on the average torque is investigated using the finite element method. Comparison with conventional VR type SRM and segment type SRM without conductive metal construction rotor show the proposed novel SRM has advantages in the torque performances and the vibration and noise characteristics. The performance is also investigated by experiment.

  3. Passive Classification of Wireless NICs during Rate Switching

    Directory of Open Access Journals (Sweden)

    Cherita L. Corbett

    2008-02-01

    Full Text Available Computer networks have become increasingly ubiquitous. However, with the increase in networked applications, there has also been an increase in difficulty to manage and secure these networks. The proliferation of 802.11 wireless networks has heightened this problem by extending networks beyond physical boundaries. We propose the use of spectral analysis to identify the type of wireless network interface card (NIC. This mechanism can be applied to support the detection of unauthorized systems that use NICs which are different from that of a legitimate system. We focus on rate switching, a vaguely specified mechanism required by the 802.11 standard that is implemented in the hardware and software of the wireless NIC. We show that the implementation of this function influences the transmission patterns of a wireless stream, which are observable through traffic analysis. Our mechanism for NIC identification uses signal processing to analyze the periodicity embedded in the wireless traffic caused by rate switching. A stable spectral profile is created from the periodic components of the traffic and used for the identity of the wireless NIC. We show that we can distinguish between NICs manufactured by different vendors and NICs manufactured by the same vendor using their spectral profiles.

  4. Passive Classification of Wireless NICs during Rate Switching

    Directory of Open Access Journals (Sweden)

    Beyah RaheemA

    2008-01-01

    Full Text Available Abstract Computer networks have become increasingly ubiquitous. However, with the increase in networked applications, there has also been an increase in difficulty to manage and secure these networks. The proliferation of 802.11 wireless networks has heightened this problem by extending networks beyond physical boundaries. We propose the use of spectral analysis to identify the type of wireless network interface card (NIC. This mechanism can be applied to support the detection of unauthorized systems that use NICs which are different from that of a legitimate system. We focus on rate switching, a vaguely specified mechanism required by the 802.11 standard that is implemented in the hardware and software of the wireless NIC. We show that the implementation of this function influences the transmission patterns of a wireless stream, which are observable through traffic analysis. Our mechanism for NIC identification uses signal processing to analyze the periodicity embedded in the wireless traffic caused by rate switching. A stable spectral profile is created from the periodic components of the traffic and used for the identity of the wireless NIC. We show that we can distinguish between NICs manufactured by different vendors and NICs manufactured by the same vendor using their spectral profiles.

  5. High-voltage high-current triggering vacuum switch

    International Nuclear Information System (INIS)

    Alferov, D.F.; Bunin, R.A.; Evsin, D.V.; Sidorov, V.A.

    2012-01-01

    Experimental investigations of switching and breaking capacities of the new high current triggered vacuum switch (TVS) are carried out at various parameters of discharge current. It has been shown that the high current triggered vacuum switch TVS can switch repeatedly a current from units up to ten kiloampers with duration up to ten millisecond [ru

  6. 49 CFR 236.342 - Switch circuit controller.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Switch circuit controller. 236.342 Section 236.342 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Instructions § 236.342 Switch circuit controller. Switch circuit controller connected at the point to switch...

  7. 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.

  8. Azo biphenyl polyurethane: Preparation, characterization and application for optical waveguide switch

    Science.gov (United States)

    Jiang, Yan; Da, Zulin; Qiu, Fengxian; Yang, Dongya; Guan, Yijun; Cao, Guorong

    2018-01-01

    Azo waveguide polymers are of particular interest in the design of materials for applications in optical switch. The aim of this contribution was the synthesis and thermo-optic waveguide switch properties of azo biphenyl polyurethanes. A series of monomers and azo biphenyl polyurethanes (Azo BPU1 and Azo BPU2) were synthesized and characterized by FT-IR, UV-Vis spectroscopy and 1H NMR. The physical and mechanical properties of thin polymer films were measured. The refractive index and thermo-optic coefficient (dn/dT) of polymer films were investigated for TE (transversal electric) polarizations by ATR technique. The transmission loss of film was measured using the Charge Coupled Device digital imaging devices. The results showed the Azo BPU2 containing chiral azobenzene chromophore had higher dn/dT and lower transmission loss. Subsequently, a 1 × 2 Y-branch and 2 × 2 Mach-Zehnder optical switches based on the prepared polymers were designed and simulated. The results showed that the power consumption of all switches was less than 1.0 mW. Compared with 1 × 2 Y-branch optical switch, the 2 × 2 Mach-Zehnder optical switches based on the same polymer have the faster response time, which were about only 1.2 and 2.0 ms, respectively.

  9. Tailoring design and fabrication of capacitive RF MEMS switches for K-band applications

    Science.gov (United States)

    Quaranta, Fabio; Persano, Anna; Capoccia, Giovanni; Taurino, Antonietta; Cola, Adriano; Siciliano, Pietro; Lucibello, Andrea; Marcelli, Romolo; Proietti, Emanuela; Bagolini, Alvise; Margesin, Benno; Bellutti, Pierluigi; Iannacci, Jacopo

    2015-05-01

    Shunt capacitive radio-frequency microelectromechanical (RF MEMS) switches were modelled, fabricated and characterized in the K-band domain. Design allowed to predict the RF behaviour of the switches as a function of the bridge geometric parameters. The modelled switches were fabricated on silicon substrate, using a surface micromachining approach. In addition to the geometric parameters, the material structure in the bridge-actuator area was modified for switches fabricated on the same wafer, thanks to the removal/addition of two technological steps of crucial importance for RF MEMS switches performance, which are the use of the sacrificial layer and the deposition of a floating metal layer on the actuator. Surface profilometry analysis was used to check the material layer structure in the different regions of the bridge area as well as to investigate the mechanical behaviour of the moveable bridge under the application of a loaded force. The RF behaviour of all the fabricated switches was measured, observing the impact on the isolation of the manipulation of the bridge size and of the variations in the fabrication process.

  10. Investigation of thyristor-based switches triggered in impact-ionization wave mode

    Science.gov (United States)

    Gusev, A. I.; Lyubutin, S. K.; Rukin, S. N.; Slovikovsky, B. G.; Tsyranov, S. N.

    2017-05-01

    An operation of the thyristor-based switches triggered in impact-ionization wave mode has been investigated. The thyristor switch contained two series connected tablet thyristors having a silicon wafer of 56 mm diameter. Applying across the switch a triggering pulse with a voltage rise rate dU/dt of over 1 kV/ns, the thyristors transition time to a conductive state was reduced to shorter than 1 ns. It is shown that the maximum amplitude of a no-failure current is increased with increasing dU/dt at the triggering stage. A possible mechanism of the dU/dt value effect on the thyristors breakdown current is discussed. Under a safety operation regime at dU/dt = 6 kV/ns (3 kV/ns per a single thyristor), the switch discharged 1-mF capacitor, which was charged to a voltage of 5 kV, to a resistive load of 18 mΩ. The following results were obtained: a peak current was 200 kA, an initial dI/dt was 58 kA/µs, a FWHM was 25 µs, and a switching efficiency was 0.97. It is shown also that a temperature of the silicon wafer is one of the main factors that affects on the thyristor switching process.

  11. Improvement of resistive switching in ZnO film by Ti doping

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongxia; Chen, Qi; Chen, Xueping [Lab of Electronic Materials and Devices, Hangzhou Dianzi University, Hangzhou 310018 (China); Mao, Qinan [State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Xi, Junhua [Lab of Electronic Materials and Devices, Hangzhou Dianzi University, Hangzhou 310018 (China); State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Ji, Zhenguo, E-mail: jizg@hdu.edu.cn [Lab of Electronic Materials and Devices, Hangzhou Dianzi University, Hangzhou 310018 (China); State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    2013-06-30

    Pt/ZnO:Ti/n{sup +}–Si structures that showed reversible and steady resistive switching behaviors were fabricated by magnetron sputtering. The stability of the devices was improved by Ti doping and the switching mechanism of the resistive switching was theoretically studied under the guidance of the first principles. The influences of different Ti atomic doping concentrations on the crystal structure and resistive switching characteristics were also investigated. The results revealed that the oxygen vacancy appears easily around the Ti ions since the formation energies of oxygen vacancies had the minimum value when it located at the next nearest neighboring to Ti atoms. - Highlights: • ZnO:Ti based resistive random access memories were fabricated. • Effects of doping concentrations on the switching characteristics were investigated. • Formation energies of oxygen vacancy in ZnO were studied by the first-principles. • The Pt/ZnO:Ti(2%)/n{sup +}–Si cell has the optimal resistive switching characteristics.

  12. Identification and Characterization of Wor4, a New Transcriptional Regulator of White-Opaque Switching

    Directory of Open Access Journals (Sweden)

    Matthew B. Lohse

    2016-03-01

    Full Text Available The human fungal pathogen Candida albicans can switch between two cell types, “white” and “opaque,” each of which is heritable through many cell divisions. Switching between these two cell types is regulated by six transcriptional regulators that form a highly interconnected circuit with multiple feedback loops. Here, we identify a seventh regulator of white-opaque switching, which we have named Wor4. We show that ectopic expression of Wor4 is sufficient to drive switching from the white to the opaque cell type, and that deletion of Wor4 blocks switching from the white to the opaque cell type. A combination of ectopic expression and deletion experiments indicates that Wor4 is positioned upstream of Wor1, and that it is formally an activator of the opaque cell type. The combination of ectopic expression and deletion phenotypes for Wor4 is unique; none of the other six white-opaque regulators show this pattern. We determined the pattern of Wor4 binding across the genome by ChIP-seq and found it is highly correlated with that of Wor1 and Wor2, indicating that Wor4 is tightly integrated into the existing white-opaque regulatory circuit. We previously proposed that white-to-opaque switching relies on the activation of a complex circuit of feedback loops that remains excited through many cell divisions. The identification of a new, central regulator of white-opaque switching supports this idea by indicating that the white-opaque switching mechanism is considerably more complex than those controlling conventional, nonheritable patterns of gene expression.

  13. Domain-general inhibition areas of the brain are involved in language switching: fMRI evidence from trilingual speakers.

    Science.gov (United States)

    de Bruin, Angela; Roelofs, Ardi; Dijkstra, Ton; Fitzpatrick, Ian

    2014-04-15

    The prevailing theory of language switching states that unbalanced bilingual speakers use inhibition to switch between their languages (Inhibitory Control or IC model; Green, 1998). Using fMRI, we examined the brain mechanisms underlying language switching and investigated the role of domain-general inhibition areas such as the right inferior frontal gyrus (rIFG) and the pre-supplementary motor area (pre-SMA). Dutch-English-German trilinguals performed a picture naming task in the MRI scanner in both a blocked-language and a mixed-language context. The rIFG and pre-SMA showed more activation for switches to the second and third language (L2 and L3) compared to non-switch trials and blocked trials. No such difference was found for switches to the first language (L1). Our results indicate that language switching recruits brain areas related to domain-general inhibition. In this way, our study supports the claim that multilinguals use inhibition to switch between their languages. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  14. Translesion Synthesis: Insights into the Selection and Switching of DNA Polymerases

    Directory of Open Access Journals (Sweden)

    Linlin Zhao

    2017-01-01

    Full Text Available DNA replication is constantly challenged by DNA lesions, noncanonical DNA structures and difficult-to-replicate DNA sequences. Two major strategies to rescue a stalled replication fork and to ensure continuous DNA synthesis are: (1 template switching and recombination-dependent DNA synthesis; and (2 translesion synthesis (TLS using specialized DNA polymerases to perform nucleotide incorporation opposite DNA lesions. The former pathway is mainly error-free, and the latter is error-prone and a major source of mutagenesis. An accepted model of translesion synthesis involves DNA polymerase switching steps between a replicative DNA polymerase and one or more TLS DNA polymerases. The mechanisms that govern the selection and exchange of specialized DNA polymerases for a given DNA lesion are not well understood. In this review, recent studies concerning the mechanisms of selection and switching of DNA polymerases in eukaryotic systems are summarized.

  15. Pneumatic switched angle spinning NMR probe with capacitively coupled double saddle coil.

    Science.gov (United States)

    Litvak, Ilya M; Espinosa, Catalina A; Shapiro, Rebecca A; Oldham, Andrew N; Duong, Vincent V; Martin, Rachel W

    2010-10-01

    Switched angle spinning (SAS) experiments can be used for generating isotropic-anisotropic correlations in oriented samples in a single experiment. In order for these methods to become widespread, specialized hardware is required. Here we describe the electronic and mechanical design and performance of a double-resonance SAS probe. Unlike many previous SAS probe implementations, the focus here is on systems where the dipolar couplings are partially averaged by molecular motion. This probe has a moving double saddle coil capacitively coupled to the stationary circuit. Angle switching is accomplished by a steam engine-type pneumatic mechanism. The speed and stability of the switching hardware for SAS experiments are demonstrated using spectra of model compounds. Copyright © 2010 Elsevier Inc. All rights reserved.

  16. Bilingual Language Switching in the Laboratory versus in the Wild: The Spatiotemporal Dynamics of Adaptive Language Control.

    Science.gov (United States)

    Blanco-Elorrieta, Esti; Pylkkänen, Liina

    2017-09-13

    For a bilingual human, every utterance requires a choice about which language to use. This choice is commonly regarded as part of general executive control, engaging prefrontal and anterior cingulate cortices similarly to many types of effortful task switching. However, although language control within artificial switching paradigms has been heavily studied, the neurobiology of natural switching within socially cued situations has not been characterized. Additionally, although theoretical models address how language control mechanisms adapt to the distinct demands of different interactional contexts, these predictions have not been empirically tested. We used MEG (RRID: NIFINV:nlx_inv_090918) to investigate language switching in multiple contexts ranging from completely artificial to the comprehension of a fully natural bilingual conversation recorded "in the wild." Our results showed less anterior cingulate and prefrontal cortex involvement for more natural switching. In production, voluntary switching did not engage the prefrontal cortex or elicit behavioral switch costs. In comprehension, while laboratory switches recruited executive control areas, fully natural switching within a conversation only engaged auditory cortices. Multivariate pattern analyses revealed that, in production, interlocutor identity was represented in a sustained fashion throughout the different stages of language planning until speech onset. In comprehension, however, a biphasic pattern was observed: interlocutor identity was first represented at the presentation of the interlocutor and then again at the presentation of the auditory word. In all, our findings underscore the importance of ecologically valid experimental paradigms and offer the first neurophysiological characterization of language control in a range of situations simulating real life to various degrees. SIGNIFICANCE STATEMENT Bilingualism is an inherently social phenomenon, interactional context fully determining language

  17. Submicrosecond Power-Switching Test Circuit

    Science.gov (United States)

    Folk, Eric N.

    2006-01-01

    A circuit that changes an electrical load in a switching time shorter than 0.3 microsecond has been devised. This circuit can be used in testing the regulation characteristics of power-supply circuits . especially switching power-converter circuits that are supposed to be able to provide acceptably high degrees of regulation in response to rapid load transients. The combination of this power-switching circuit and a known passive constant load could be an attractive alternative to a typical commercially available load-bank circuit that can be made to operate in nominal constant-voltage, constant-current, and constant-resistance modes. The switching provided by a typical commercial load-bank circuit in the constant-resistance mode is not fast enough for testing of regulation in response to load transients. Moreover, some test engineers do not trust the test results obtained when using commercial load-bank circuits because the dynamic responses of those circuits are, variously, partly unknown and/or excessively complex. In contrast, the combination of this circuit and a passive constant load offers both rapid switching and known (or at least better known) load dynamics. The power-switching circuit (see figure) includes a signal-input section, a wide-hysteresis Schmitt trigger that prevents false triggering in the event of switch-contact bounce, a dual-bipolar-transistor power stage that drives the gate of a metal oxide semiconductor field-effect transistor (MOSFET), and the MOSFET, which is the output device that performs the switching of the load. The MOSFET in the specific version of the circuit shown in the figure is rated to stand off a potential of 100 V in the "off" state and to pass a current of 20 A in the "on" state. The switching time of this circuit (the characteristic time of rise or fall of the potential at the drain of the MOSFET) is .300 ns. The circuit can accept any of three control inputs . which one depending on the test that one seeks to perform: a

  18. Bipolar resistive switching in different plant and animal proteins

    KAUST Repository

    Bag, A.

    2014-06-01

    We report bipolar resistive switching phenomena observed in different types of plant and animal proteins. Using protein as the switching medium, resistive switching devices have been fabricated with conducting indium tin oxide (ITO) and Al as bottom and top electrodes, respectively. A clockwise bipolar resistive switching phenomenon is observed in all proteins. It is shown that the resistive switching phenomena originate from the local redox process in the protein and the ion exchange from the top electrode/protein interface.

  19. Electrical permeability and domain switching effect on fracture behavior of piezoelectric material

    Science.gov (United States)

    Kalyanam, Sureshkumar

    The crystal structure and domain microstructure within each grain of a piezoelectric material and 90°, 180° polarization switch observed experimentally are discussed. The work and internal energy density domain switching criteria are used to predict domain switch zones near crack tip of CT fracture specimen. Constitutive relations are modified to reflect changes in material properties and strains arising from domain switch. An incremental finite element solution procedure using UNIX program was developed to use ABAQUS piezoelectric FEA software along with FORTRAN codes for prediction and modeling of domain switching in piezoelectric material. Insulating materials like silicone oil are used by researchers to prevent electric arcing between crack faces during fracture tests with piezoelectric material. A finite element (UEL) was developed to model dielectric medium filling crack cavity of piezoelectric fracture test specimens. An iterative procedure was adopted to solve geometrically nonlinear crack opening using an UNIX program. The effect of permeability of crack cavity medium on near tip electric fields in CT fracture specimen was investigated. A CT fracture specimen was modeled using incremental domain switch finite element solution procedure. Domain switch zones in the vicinity of the crack tip were obtained for various electrical and mechanical fracture loads applied. The effect of actual crack profile on near tip domain switch zones, opening stress, stress intensity is discussed. A gradual polarization switch model which considers the gradual change in the average polarization direction from the original poling direction was developed. Fracture load predictions using stress intensity factor obtained from assuming linear material behavior, nonlinear behavior using the instantaneous and gradual polarization switch model are compared. Gradual polarization switch model was used to model a SENB fracture specimen to obtain the near tip strain field and compare it

  20. A fundamental trade-off in covalent switching and its circumvention by enzyme bifunctionality in glucose homeostasis.

    Science.gov (United States)

    Dasgupta, Tathagata; Croll, David H; Owen, Jeremy A; Vander Heiden, Matthew G; Locasale, Jason W; Alon, Uri; Cantley, Lewis C; Gunawardena, Jeremy

    2014-05-09

    Covalent modification provides a mechanism for modulating molecular state and regulating physiology. A cycle of competing enzymes that add and remove a single modification can act as a molecular switch between "on" and "off" and has been widely studied as a core motif in systems biology. Here, we exploit the recently developed "linear framework" for time scale separation to determine the general principles of such switches. These methods are not limited to Michaelis-Menten assumptions, and our conclusions hold for enzymes whose mechanisms may be arbitrarily complicated. We show that switching efficiency improves with increasing irreversibility of the enzymes and that the on/off transition occurs when the ratio of enzyme levels reaches a value that depends only on the rate constants. Fluctuations in enzyme levels, which habitually occur due to cellular heterogeneity, can cause flipping back and forth between on and off, leading to incoherent mosaic behavior in tissues, that worsens as switching becomes sharper. This trade-off can be circumvented if enzyme levels are correlated. In particular, if the competing catalytic domains are on the same protein but do not influence each other, the resulting bifunctional enzyme can switch sharply while remaining coherent. In the mammalian liver, the switch between glycolysis and gluconeogenesis is regulated by the bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2). We suggest that bifunctionality of PFK-2/FBPase-2 complements the metabolic zonation of the liver by ensuring coherent switching in response to insulin and glucagon.

  1. Negative differential resistive switching in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) thin film through electrohydrodynamic atomization

    Science.gov (United States)

    Awais, Muhammad Naeem; Jo, Jeong-Dai; Choi, Kyung Hyun

    2013-10-01

    Polymeric negative differential resistive (NDR) switching was explored based on the sandwiched structure of indium titanium oxide (ITO) coated polyethyleneterepthalate(PET)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)/silver(Ag) through electrohydrodynamic atomization (EHDA) printing technique. The NDR switching in the fabricated device with the structure of ITO/PEDOT:PSS/Ag was analyzed through semiconductor device analyzer under polarity dependent bipolar sweeping voltage of less than . Effect of the current compliance (CC) in the NDR switching of the fabricated switch has been demonstrated. Multiple resistive switching sweeps were taken to scrutinize the robustness of the fabricated device over 100 cycles. The non-volatility of the as-fabricated device was checked against different time stresses over 2500 s. The switching mechanism is proposed to be due to the transition between PEDOT+ and PEDOT0 chains. The current conduction mechanism involved in the PEDOT:PSS based NDR switches is attributed to the ohmic conduction at lower voltages, while space charge limited conduction and NDR effects were prominent due to the injection of carriers at higher voltages.

  2. Analytical Modeling and Simulation of Four-Switch Hybrid Power Filter Working with Sixfold Switching Symmetry

    Czech Academy of Sciences Publication Activity Database

    Tlustý, J.; Škramlík, Jiří; Švec, J.; Valouch, Viktor

    2012-01-01

    Roč. 2012, č. 292178 (2012), s. 1-17 ISSN 1024-123X Institutional support: RVO:61388998 Keywords : analytical modeling * four-switch hybrid power filter * sixfold switching symmetry Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.383, year: 2012 http://www.hindawi.com/journals/mpe/2012/292178/

  3. Optimization of multi-branch switched diversity systems

    KAUST Repository

    Nam, Haewoon

    2009-10-01

    A performance optimization based on the optimal switching threshold(s) for a multi-branch switched diversity system is discussed in this paper. For the conventional multi-branch switched diversity system with a single switching threshold, the optimal switching threshold is a function of both the average channel SNR and the number of diversity branches, where computing the optimal switching threshold is not a simple task when the number of diversity branches is high. The newly proposed multi-branch switched diversity system is based on a sequence of switching thresholds, instead of a single switching threshold, where a different diversity branch uses a different switching threshold for signal comparison. Thanks to the fact that each switching threshold in the sequence can be optimized only based on the number of the remaining diversity branches, the proposed system makes it easy to find these switching thresholds. Furthermore, some selected numerical and simulation results show that the proposed switched diversity system with the sequence of optimal switching thresholds outperforms the conventional system with the single optimal switching threshold. © 2009 IEEE.

  4. Switched capacitor DC-DC converter with switch conductance modulation and Pesudo-fixed frequency control

    DEFF Research Database (Denmark)

    Larsen, Dennis Øland; Vinter, Martin; Jørgensen, Ivan Harald Holger

    A switched capacitor dc-dc converter with frequency-planned control is presented. By splitting the output stage switches in eight segments the output voltage can be regulated with a combination of switching frequency and switch conductance. This allows for switching at predetermined frequencies, 31.......25 kHz, 250 kHz, 500 kHz, and 1 MHz, while maintaining regulation of the output voltage. The controller is implemented in 180 CMOS with a 1/3 series-parallel output stage designed for 3.6–4.2 V input, 1.2 V output, and 1–40 mA load current. The proposed controller is compared with a co-integrated pulse...

  5. Pressure-induced switching in ferroelectrics: Phase-field modeling, electrochemistry, flexoelectric effect, and bulk vacancy dynamics

    Science.gov (United States)

    Cao, Ye; Morozovska, Anna; Kalinin, Sergei V.

    2017-11-01

    Pressure-induced polarization switching in ferroelectric thin films has emerged as a powerful method for domain patterning, allowing us to create predefined domain patterns on free surfaces and under thin conductive top electrodes. However, the mechanisms for pressure-induced polarization switching in ferroelectrics remain highly controversial, with flexoelectricity, polarization rotation and suppression, and bulk and surface electrochemical processes all being potentially relevant. Here we classify possible pressure-induced switching mechanisms, perform elementary estimates, and study in depth using phase-field modeling. We show that magnitudes of these effects are remarkably close and give rise to complex switching diagrams as a function of pressure and film thickness with nontrivial topology or switchable and nonswitchable regions.

  6. Switching between phenotypes and population extinction

    Science.gov (United States)

    Lohmar, Ingo; Meerson, Baruch

    2011-11-01

    Many types of bacteria can survive under stress by switching stochastically between two different phenotypes: the “normals” who multiply fast, but are vulnerable to stress, and the “persisters” who hardly multiply, but are resilient to stress. Previous theoretical studies of such bacterial populations have focused on the fitness: the asymptotic rate of unbounded growth of the population. Yet for an isolated population of established (and not very large) size, a more relevant measure may be the population extinction risk due to the interplay of adverse extrinsic variations and intrinsic noise of birth, death and switching processes. Applying a WKB approximation to the pertinent master equation of such a two-population system, we quantify the extinction risk, and find the most likely path to extinction under both favorable and adverse conditions. Analytical results are obtained both in the biologically relevant regime when the switching is rare compared with the birth and death processes, and in the opposite regime of frequent switching. We show that rare switches are most beneficial in reducing the extinction risk.

  7. Ways to Optimize Analogue Switched Circuits

    Directory of Open Access Journals (Sweden)

    J. Hospodka

    2008-12-01

    Full Text Available This paper describes how analogue switched circuits (switched-capacitor and switched-current circuits can be optimized by means of a personal computer. The optimization of this kind of circuits is not so common and their analysis is more difficult in comparison with continuously working circuits. Firstly, the nonidealities occurring in these circuits whose effect on their characteristics should be optimized are discussed. Then a few ways to analyze analogue switched circuits are shown. From all optimization algorithms applicable for this kind of optimization, two ones that seem to be the most promising are proposed. The differential evolution (one of evolutionary algorithms combined with the simplex method was found to be most appropriate from these two ones. Two types of programs are required for the optimization of these circuits: a program for implementing calculations of the used optimization algorithm and a program for the analysis of the optimized circuit. Several suitable computer programs from both of the groups together with their proper settings according to authors’ experience are proposed. At the end of the paper, an example of a switched-current circuit optimization documenting the previous description is presented.

  8. Arduino Based RFID Line Switching Using SSR

    Directory of Open Access Journals (Sweden)

    Michael E.

    2017-10-01

    Full Text Available The importance of line switching cannot be overemphasized as they are used to connect and disconnect substations to and from a distribution grid. At the cradle of technology line switching was achieved via the use of manual switches or fuses which could endanger life as a result of electrocution when expose during maintenance. This ill prompted the development of automated line switching using relays and contactors. With time this tends to fail as a result of wearing of the contact which is as a result of arcing and low voltage. To avert all these ills this paper presents Arduino based Radio Frequency Identification RFID line switching using Solid State Relay SSR. This is to ensure the safety of operators or technologist and to also avert the problem associated with relays and contactors using SSR. This was achieved using RFID RC-522 reader ardriuno Uno SSR and other discrete components. The system was tested and worked perfectly reducing the risk of electrocution and eliminating damage wearing of the contacts common with contactors and relays.

  9. Commitment and Switching Intentions: Customers and Brands

    Directory of Open Access Journals (Sweden)

    Juliana Werneck Rodrigues

    2012-12-01

    Full Text Available This study aims to evaluate the relationship between a customer’s brand switching intentions and his commitment to a brand. Based on a literature review, constructs related to customer brand commitment were identified (affective and continuance commitment, trust, satisfaction, switching costs and alternative attractiveness and their roles in the formation of brand switching intentions hypothesized. Through a cross-sectional survey, a sample of 201 smartphone users was collected to test the proposed relationships. Data analysis was carried out via structural equations modeling, with direct effects of trust, satisfaction, switching costs and alternative attractiveness upon the different kinds of commitment being verified. Furthermore, both types of brand commitment (affective and continuance were found to negatively impact a customer’s intention to switch brands. Regarding enterprise customer strategies, the research findings suggest that, if firms are able to track customer brand commitment, they could use such knowledge to develop better relationship strategies, minimizing customer defection and further developing customer value to the company.

  10. Nanoelectromechanical Switches for Low-Power Digital Computing

    Directory of Open Access Journals (Sweden)

    Alexis Peschot

    2015-08-01

    Full Text Available The need for more energy-efficient solid-state switches beyond complementary metal-oxide-semiconductor (CMOS transistors has become a major concern as the power consumption of electronic integrated circuits (ICs steadily increases with technology scaling. Nano-Electro-Mechanical (NEM relays control current flow by nanometer-scale motion to make or break physical contact between electrodes, and offer advantages over transistors for low-power digital logic applications: virtually zero leakage current for negligible static power consumption; the ability to operate with very small voltage signals for low dynamic power consumption; and robustness against harsh environments such as extreme temperatures. Therefore, NEM logic switches (relays have been investigated by several research groups during the past decade. Circuit simulations calibrated to experimental data indicate that scaled relay technology can overcome the energy-efficiency limit of CMOS technology. This paper reviews recent progress toward this goal, providing an overview of the different relay designs and experimental results achieved by various research groups, as well as of relay-based IC design principles. Remaining challenges for realizing the promise of nano-mechanical computing, and ongoing efforts to address these, are discussed.

  11. Switching between bistable states in a discrete nonlinear model with long-range dispersion

    DEFF Research Database (Denmark)

    Johansson, Magnus; Gaididei, Yuri B.; Christiansen, Peter Leth

    1998-01-01

    In the framework of a discrete nonlinear Schrodinger equation with long-range dispersion, we propose a general mechanism for obtaining a controlled switching between bistable localized excitations. We show that the application of a spatially symmetric kick leads to the excitation of an internal...

  12. General Analysis of Vacuum Circuit Breaker Switching Overvoltages in Offshore Wind Farms

    DEFF Research Database (Denmark)

    Ghafourian, S. M.; Arana, I.; Holbøll, Joachim

    2016-01-01

    Understanding mechanisms of switching transient overvoltages in modern electrical power systems is a necessity to ensure a proper design of power plants and switchgear and the required level of reliable and secure system operation. High fidelity plant modelling and accurate transient analysis is ...

  13. Phylogenetic analyses of the leaf beetle genus Galerucella: evidence for host switching at speciation?

    NARCIS (Netherlands)

    Borghuis, A.; Madsen, O.; Ouborg, N.J.; Groenendael, van J.

    2009-01-01

    It is still the subject of lively debate whether sympatric speciation is a general mode of speciation as opposed to allopatric speciation. In herbivorous insects, host switching, i.e. colonization of, and adaptation to, a new host by a herbivore, has been proposed as one of the driving mechanisms of

  14. Experimental Validation of Topology Optimization for RF MEMS Capacitive Switch Design

    DEFF Research Database (Denmark)

    Philippine, Mandy Axelle; Zareie, Hosein; Sigmund, Ole

    2013-01-01

    In this paper, we present 30 distinct RF MEMS capacitive switch designs that are the product of topology optimizations that control key mechanical properties such as stiffness, response to intrinsic stress gradients, and temperature sensitivity. The designs were evaluated with high-accuracy simul...

  15. Finite-time boundedness and stabilisation of switched linear systems using event-triggered controllers

    NARCIS (Netherlands)

    Qi, Yiwen; Cao, Ming

    2017-01-01

    This study proposes a systematic control design approach to consider jointly the event-triggered communication mechanism and state-feedback control for switched linear systems. The systems determine the necessary samplings of the feedback signal by constructing predefined events that can reduce

  16. Electronic bipolar resistive switching behavior in Ni/VOx/Al device

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Mengseng [School of Electronic Information Engineering, Hebei University of Technology, Tianjin Key Laboratory of Electronic Materials and Devices, Tianjin 300130 (China); School of Electronic Information Engineering, Tianjin Key Laboratory of Film Electronic & Communication Devices, Tianjin University of Technology, Tianjin 300384 (China); Zhang, Kailiang, E-mail: kailiang_zhang@163.com [School of Electronic Information Engineering, Tianjin Key Laboratory of Film Electronic & Communication Devices, Tianjin University of Technology, Tianjin 300384 (China); Yang, Ruixia, E-mail: yangrx@hebut.edu.cn [School of Electronic Information Engineering, Hebei University of Technology, Tianjin Key Laboratory of Electronic Materials and Devices, Tianjin 300130 (China); Wang, Fang; Zhang, Zhichao; Wu, Shijian [School of Electronic Information Engineering, Tianjin Key Laboratory of Film Electronic & Communication Devices, Tianjin University of Technology, Tianjin 300384 (China)

    2017-07-15

    Highlights: • The resistive random access memory of Ni/VOx/Al was fabricated. • The device has the electronic bipolar resistive switching characteristic. • The activity energy (Ea) of HRS has been calculated. • The reasons of the degradation of the resistance ratio of HRS/LRS were analyzed. - Abstract: In this paper, the Ni/VOx/Al resistive random access memory (RRAM) device is constructed and it shows bipolar resistive switching behavior, low resistive state (LRS) nonlinearity, and good retention. The set and reset processes are likely induced by the electron trapping and detrapping of trapping centers in the VOx films, respectively. The conduction mechanism in negative/positive region are controlled by space charge limited current mechanism (SCLC)/Schottky emission. The temperature dependence of I–V curves for HRS is measured to confirm the defects trapping and detrapping electrons model. activation energy was calculated to analyze the endurance performance of the device. The detailed analysis of the switching behavior with SCLC mechanism and Schottky emission mechanism could provide useful information for electronic bipolar resistive switching (eBRS) characteristics.

  17. Enhanced oxidative stress and the glycolytic switch in superficial urothelial carcinoma of urinary bladder

    Directory of Open Access Journals (Sweden)

    Yu-Wei Lai

    2016-12-01

    Conclusions: UC of the UB manifested that the glycolytic phenotype would reflect the Warburg effect. We suggest that the molecular mechanism in the regulation of glycolytic switch in UC of the UB might provide a specific biomarker for the future development of cancer diagnosis.

  18. Key Players in the Genetic Switch of Bacteriophage TP901-1

    DEFF Research Database (Denmark)

    Alsing, Anne; Pedersen, Margit; Sneppen, Kim

    2011-01-01

    the bistable genetic switch of bacteriophage TP901-1 through experiments and statistical mechanical modeling. We examine the activity of the lysogenic promoter Pr at different concentrations of the phage repressor, CI, and compare the effect of CI on Pr in the presence or absence of the phage-encoded MOR...

  19. Electronic bipolar resistive switching behavior in Ni/VOx/Al device

    International Nuclear Information System (INIS)

    Xia, Mengseng; Zhang, Kailiang; Yang, Ruixia; Wang, Fang; Zhang, Zhichao; Wu, Shijian

    2017-01-01

    Highlights: • The resistive random access memory of Ni/VOx/Al was fabricated. • The device has the electronic bipolar resistive switching characteristic. • The activity energy (Ea) of HRS has been calculated. • The reasons of the degradation of the resistance ratio of HRS/LRS were analyzed. - Abstract: In this paper, the Ni/VOx/Al resistive random access memory (RRAM) device is constructed and it shows bipolar resistive switching behavior, low resistive state (LRS) nonlinearity, and good retention. The set and reset processes are likely induced by the electron trapping and detrapping of trapping centers in the VOx films, respectively. The conduction mechanism in negative/positive region are controlled by space charge limited current mechanism (SCLC)/Schottky emission. The temperature dependence of I–V curves for HRS is measured to confirm the defects trapping and detrapping electrons model. activation energy was calculated to analyze the endurance performance of the device. The detailed analysis of the switching behavior with SCLC mechanism and Schottky emission mechanism could provide useful information for electronic bipolar resistive switching (eBRS) characteristics.

  20. Polarity-Free Resistive Switching Characteristics of CuxO Films for Non-volatile Memory Applications

    International Nuclear Information System (INIS)

    Hang-Bing, Lv; Peng, Zhou; Xiu-Feng, Fu; Ming, Yin; Ya-Li, Song; Li, Tang; Ting-Ao, Tang; Yin-Yin, Lin

    2008-01-01

    Resistive switching characteristics of Cu x O films grown by plasma oxidation process at room temperature are investigated. Both bipolar and unipolar stable resistive switching behaviours are observed and confirmed by repeated current–voltage measurements. It is found that the RESET current is dependent on SET compliance current. The mechanism behind this new phenomenon can be understood in terms of conductive filaments formation/rupture with the contribution of Joule heating

  1. Magnetic switch for reactor control rod. [LMFBR

    Science.gov (United States)

    Germer, J.H.

    1982-09-30

    A magnetic reed switch assembly is described for activating an electromagnetic grapple utilized to hold a control rod in position above a reactor core. In normal operation the magnetic field of a permanent magnet is short-circuited by a magnetic shunt, diverting the magnetic field away from the reed switch. The magnetic shunt is made of a material having a Curie-point at the desired release temperature. Above that temperature the material loses its ferromagnetic properties, and the magnetic path is diverted to the reed switch which closes and short-circuits the control circuit for the control rod electro-magnetic grapple which allows the control rod to drop into the reactor core for controlling the reactivity of the core.

  2. New Photonic System for Optical Packet Switching

    Directory of Open Access Journals (Sweden)

    F. Rudge Barbosa

    2003-08-01

    Full Text Available Fast optical switching (ms timebase is realized by using a RF frequency tone inserted in the optical packet that carries a digital payload. By using a highly selective RF filtering for optical packet header frequency recognition, we have obtained excellent performance in optical switching function.. The RF header is detected at optical node input, and signals the node switching control, which instantly directs the packet to a prescribed output. No electronic processing of the digital payload is performed. The optical circuit is noise-free, has very low crosstalk, and is extremely selective in header frequency detection. BER measurements for payload consistently yield figures as low as 10-12 . This system is applicable to optical metropolitan and access networks, and is fully compatible with DWDM systems.

  3. Huge capacity optical packet switching and buffering.

    Science.gov (United States)

    Shinada, Satoshi; Furukawa, Hideaki; Wada, Naoya

    2011-12-12

    We demonstrate 2.56 Tbit/s/port dual-polarization DWDM/DQPSK variable-length optical packet (20 Gbit/s × 64 wavelengths × 2 polarizations) switching and buffering by using a 2×2 optical packet switch (OPS) system. The optical data plane of the OPS system was constructed of multi-connected electro-optical switches and fiber delay lines. The accumulated polarization dependent loss of each optical path in the data plane was less than 5 dB. This low-polarization-dependence OPS system enabled us to handle DWDM/DQPSK optical packets (1.28 Tbit/s/port) with time-varying polarization after transmission through 100 km fiber in the field. © 2011 Optical Society of America

  4. Metallic oxide switches using thick film technology

    Science.gov (United States)

    Patel, D. N.; Williams, L., Jr.

    1974-01-01

    Metallic oxide thick film switches were processed on alumina substrates using thick film technology. Vanadium pentoxide in powder form was mixed with other oxides e.g., barium, strontium copper and glass frit, ground to a fine powder. Pastes and screen printable inks were made using commercial conductive vehicles and appropriate thinners. Some switching devices were processed by conventional screen printing and firing of the inks and commercial cermet conductor terminals on 96% alumina substrates while others were made by applying small beads or dots of the pastes between platinum wires. Static, and dynamic volt-ampere, and pulse tests indicate that the switching and self-oscillatory characteristics of these devices could make them useful in memory element, oscillator, and automatic control applications.

  5. Switching overvoltages in offshore wind power grids

    DEFF Research Database (Denmark)

    Arana Aristi, Ivan

    Switching transients in wind turbines, the collection grid, the export system and the external grid in offshore wind farms, during normal or abnormal operation, are the most important phenomena when conducting insulation coordination studies. However, the recommended models and methods from...... electrical systems and the topic of transients is given in Chapter 1. In Chapter 2 it is described how the component and sub-system models are developed and used from an applied point of view, where common and detail models are mentioned. In Chapter 3 results from frequency domain measurement on transformers...... and cables are presented. In Chapter 4 results from time domain measurements and simulations of switching operations in offshore wind power grids are described. Specifically, switching operations on a single wind turbine, the collection grid, the export system and the external grid measured in several real...

  6. Radio frequency-assisted fast superconducting switch

    Science.gov (United States)

    Solovyov, Vyacheslav; Li, Qiang

    2017-12-05

    A radio frequency-assisted fast superconducting switch is described. A superconductor is closely coupled to a radio frequency (RF) coil. To turn the switch "off," i.e., to induce a transition to the normal, resistive state in the superconductor, a voltage burst is applied to the RF coil. This voltage burst is sufficient to induce a current in the coupled superconductor. The combination of the induced current with any other direct current flowing through the superconductor is sufficient to exceed the critical current of the superconductor at the operating temperature, inducing a transition to the normal, resistive state. A by-pass MOSFET may be configured in parallel with the superconductor to act as a current shunt, allowing the voltage across the superconductor to drop below a certain value, at which time the superconductor undergoes a transition to the superconducting state and the switch is reset.

  7. 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.

  8. Weight change after an atypical antipsychotic switch.

    Science.gov (United States)

    Ried, L Douglas; Renner, Bernard T; Bengtson, Michael A; Wilcox, Brian M; Acholonu, Wilfred W

    2003-10-01

    Atypical antipsychotics successfully treat schizophrenia and other conditions, with a lower incidence of extrapyramidal side effects than other agents used in treatment of these disorders. However, some atypical antipsychotics are associated with weight gain. To quantify the impact on weight and identify atypical antipsychotics causing the least amount of weight gain among patients switched from risperidone to olanzapine and olanzapine to risperidone. Patients included in the study (n = 86) were > or =18 years and had received > or =2 prescriptions for risperidone or olanzapine for > or =60 days, switched to the other atypical antipsychotic, and were dispensed > or =2 prescriptions for at least 60 days after the index date. Age, weight, and body mass index (BMI) were retrospectively abstracted from automated databases containing patient-specific prescription and vital sign information. At the time of their switch, the average patient age was 53.2 years (range 25-83). The average weight change in patients switched to olanzapine (n = 47) was +2.3 kg (p = 0.01) and the BMI change was +0.8 kg/m(2) (p = 0.02). The average percent body weight change was +2.8% and the BMI change was +3.0%. The average weight change after patients switched to risperidone (n = 39) was -0.45 kg (p = 0.69) and BMI change was -0.2 kg/m2 (p = 0.64). The average percentage weight change was -0.4% and BMI change was -0.5%. Practitioners' concern regarding weight changes after switching atypical antipsychotics seems warranted and patients should be provided consistent, ongoing weight monitoring. Further investigations should examine whether weight changes associated with atypical antipsychotic treatment further jeopardize this already at-risk population for severe comorbid conditions such as hypertension, coronary artery disease, and type 2 diabetes.

  9. Photonic Switching Devices Using Light Bullets

    Science.gov (United States)

    Goorjian, Peter M. (Inventor)

    1999-01-01

    A unique ultra-fast, all-optical switching device or switch is made with readily available, relatively inexpensive, highly nonlinear optical materials. which includes highly nonlinear optical glasses, semiconductor crystals and/or multiple quantum well semiconductor materials. At the specified wavelengths. these optical materials have a sufficiently negative group velocity dispersion and high nonlinear index of refraction to support stable light bullets. The light bullets counter-propagate through, and interact within the waveguide to selectively change each others' directions of propagation into predetermined channels. In one embodiment, the switch utilizes a rectangularly planar slab waveguide. and further includes two central channels and a plurality of lateral channels for guiding the light bullets into and out of the waveguide. An advantage of the present all-optical switching device lies in its practical use of light bullets, thus preventing the degeneration of the pulses due to dispersion and diffraction at the front and back of the pulses. Another advantage of the switching device is the relative insensitivity of the collision process to the time difference in which the counter-propagating pulses enter the waveguide. since. contrary to conventional co-propagating spatial solitons, the relative phase of the colliding pulses does not affect the interaction of these pulses. Yet another feature of the present all-optical switching device is the selection of the light pulse parameters which enables the generation of light bullets in nonlinear optical materials. including highly nonlinear optical glasses and semiconductor materials such as semiconductor crystals and/or multiple quantum well semiconductor materials.

  10. Manufacturing fuel-switching capability, 1988

    Energy Technology Data Exchange (ETDEWEB)

    1991-09-01

    Historically, about one-third of all energy consumed in the United States has been used by manufacturers. About one-quarter of manufacturing energy is used as feedstocks and raw material inputs that are converted into nonenergy products; the remainder is used for its energy content. During 1988, the most recent year for which data are available, manufacturers consumed 15.5 quadrillion British thermal units (Btu) of energy to produce heat and power and to generate electricity. The manufacturing sector also has widespread capabilities to switch from one fuel to another for either economic or emergency reasons. There are numerous ways to define fuel switching. For the purposes of the Manufacturing Energy Consumption Survey (MECS), fuel switching is defined as the capability to substitute one energy source for another within 30 days with no significant modifications to the fuel-consuming equipment, while keeping production constant. Fuel-switching capability allows manufacturers substantial flexibility in choosing their mix of energy sources. The consumption of a given energy source can be maximized if all possible switching into that energy source takes place. The estimates in this report are based on data collected on the 1988 Manufacturing Energy Consumption Survey (MECS), Forms 846 (A through C). The EIA conducts this national sample survey of manufacturing energy consumption on a triennial basis. The MECS is the only comprehensive source of national-level data on energy-related information for the manufacturing industries. The MECS was first conducted in 1986 to collect data for 1985. This report presents information on the fuel-switching capabilities of manufacturers in 1988. This report is the second of a series based on the 1988 MECS. 8 figs., 31 tabs.

  11. Manufacturing fuel-switching capability, 1988

    International Nuclear Information System (INIS)

    1991-09-01

    Historically, about one-third of all energy consumed in the United States has been used by manufacturers. About one-quarter of manufacturing energy is used as feedstocks and raw material inputs that are converted into nonenergy products; the remainder is used for its energy content. During 1988, the most recent year for which data are available, manufacturers consumed 15.5 quadrillion British thermal units (Btu) of energy to produce heat and power and to generate electricity. The manufacturing sector also has widespread capabilities to switch from one fuel to another for either economic or emergency reasons. There are numerous ways to define fuel switching. For the purposes of the Manufacturing Energy Consumption Survey (MECS), fuel switching is defined as the capability to substitute one energy source for another within 30 days with no significant modifications to the fuel-consuming equipment, while keeping production constant. Fuel-switching capability allows manufacturers substantial flexibility in choosing their mix of energy sources. The consumption of a given energy source can be maximized if all possible switching into that energy source takes place. The estimates in this report are based on data collected on the 1988 Manufacturing Energy Consumption Survey (MECS), Forms 846 (A through C). The EIA conducts this national sample survey of manufacturing energy consumption on a triennial basis. The MECS is the only comprehensive source of national-level data on energy-related information for the manufacturing industries. The MECS was first conducted in 1986 to collect data for 1985. This report presents information on the fuel-switching capabilities of manufacturers in 1988. This report is the second of a series based on the 1988 MECS. 8 figs., 31 tabs

  12. Energy Transformations in a Self-Excited Switched Reluctance Generator

    Directory of Open Access Journals (Sweden)

    Abelardo Martinez-Iturbe

    2016-04-01

    Full Text Available Wind generation systems require mechanisms that allow optimal adaptation of the generator to varying wind speed and to extract maximum energy from the wind. Robust and affordable high-performance methods are also needed for isolated sites. This paper takes this approach, in which an AC switched reluctance generator is used as a generator with a variable rotor speed. Although the voltage obtained is of insufficient quality to connect the generator directly to the power grid, this kind of generator can be used in isolated sites to charge a battery bank with a simple bridge rectifier. Due to the nonlinear behavior of the machine with the position and current, along with the alternating nature of the current that circulates through its phases, the machine experiences cyclical energy transformations of a mechanical, electrical and magnetic nature. This paper analyzes these transformations for the purpose of providing guidelines for machine design and optimization as a wind turbine in isolated sites.

  13. Switching to a Mac For Dummies

    CERN Document Server

    Reinhold, Arnold

    2007-01-01

    Thinking of making the switch from your PC to a Mac? Congratulations! You're in for a great, virus-free ride. And Switching to Mac For Dummies makes it smoother than you ever imagined. From buying the Mac that's right for you to transferring your files to breaking your old Windows habits and learning to do things the (much easier) Mac way, it makes the whole process practically effortless. Whether you've been using Windows XP, Vista, or even Linux, you'll find simple, straightforward ways to make your transition go smoothly. That will leave you plenty of time to get familiar with Mac'

  14. The Morrison Bearingless Switched Reluctance Motor

    Science.gov (United States)

    Wong, David S.

    2004-01-01

    Switched reluctance motors typically consist of pairs of poles protruding outward from a central rotor, surrounded by pairs of coils protruding inward from a stator. The pairs of coils, positioned a short distance from opposing sides of the rotor, are connected in series. A current runs through the coils, generating a magnetic flux between the coils. This attracts the protruding poles on the rotor, and just as the poles on the rotor approach the coils, the current to the coils is inverted, repelling the rotor s poles as they pass the coils. This current switching, back and forth, provides a continuous rotational torque to the rotor. reliability, durability, low cost, and operation in adverse environments such as high temperatures, extreme temperature variations, and high rotational speeds. However, because rotors are often manufactured with minute flaws due to imperfections in the machining process, traditional switched reluctance motors often suffer from substantial amounts of vibration. In addition, the current in the coils imparts a strong radial magnetic force on the rotor; the continuous alternating of the direction of this force also causes vibration. As a result, switched reluctance motors require bearings that, run at high speeds, can require lubrication apparatus and are subject to problems with heat and wear. My mentor s recent invention, the "Bearingless" Switched Reluctance Motor, actually uses magnetic bearings instead of traditional physical bearings. Sensors are used to continuously determine the position of the rotor. A computer reads the position sensor input, performs calculations, and outputs a current to a set of extra coils (in addition to the coils rotating the rotor). This current provides a magnetic force that counters and damps the vibration. The sense-calculate-update loop iterates more than thirty thousand times per second. For now, our goal is to have the rotor rotate at about 6000 rprn, and at that speed, the magnetic bearing is

  15. Simulation of plasma erosion opening switches

    International Nuclear Information System (INIS)

    Mason, R.J.; Jones, M.E.

    1988-01-01

    Recent progress in the modeling of Plasma Erosion Opening Switches is reviewed, and new results from both fluid and particle simulation compared. Three-fluid simulations with the ANTHEM code for switches on the NRL GAMBLE I machine and SNL PBFA II machine have shown strong dependence of the opening dynamics on the anode structure, the threshold for electron emission, on the possible presence of anomalous resistivity, and on advection of the magnetic field with cathode emitted electrons. Simulations with the implicit particle-in-cell code ISIS confirm these observations, but manifest broader current channels---in better agreement with GAMBLE I experimental results. 7 refs., 3 figs

  16. Design of a Clap Activated Switch

    Directory of Open Access Journals (Sweden)

    Seyi Stephen OLOKEDE

    2008-12-01

    Full Text Available This paper presents the design of a clap activated switch device that will serve well in different phono-controlled applications, providing inexpensive key and at the same time flee from false triggering.This involves the design of various sages consisting of the pickup transducer, low frequency, audio low power and low noise amplifier, timer, bistable and switches. It also consists of special network components to prevent false triggering and ensure desired performance objectives. A decade counter IC serves the bistable function instead of flip-flop, special transistor and edge triggering network for low audio frequency.

  17. Open switching of current varying inductance

    International Nuclear Information System (INIS)

    Zubkov, P.I.; Lukyanchikov, L.A.; Ten, K.A.

    1990-01-01

    The electromotive force of induction occurs in a varying inductance of a current circuit part. It can be used to control and switch the current. The effect, occurring under the forced inductance decrease, is used widely for explosive magnetic generators to produce high currents, to store high-density energy and to generate superhigh magnetic fields. This paper gives an analysis of open switching of the currents by varying inductance in some simple electrotechnical models of circuits used in pulse power engineering to obtain high energies

  18. Switching between intravenous and subcutaneous trastuzumab

    DEFF Research Database (Denmark)

    Gligorov, Joseph; Curigliano, Giuseppe; Müller, Volkmar

    2017-01-01

    AIM: To assess the safety and tolerability of switching between subcutaneous (SC) and intravenous (IV) trastuzumab in the PrefHer study (NCT01401166). PATIENTS AND METHODS: Patients with HER2-positive early breast cancer completed (neo)adjuvant chemotherapy and were randomised to receive four....... Rates of clinically important events, including grade ≥3 AEs, serious AEs, AEs leading to study drug discontinuation and cardiac AEs, were low and similar between treatment arms (safety signals for trastuzumab were observed. CONCLUSIONS: PrefHer revealed...... that switching from IV to SC trastuzumab (hand-held syringe or SID) or vice versa did not impact the known safety profile of trastuzumab....

  19. A novel photonic crystal fibre switch

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Hermann, D.S.; Broeng, Jes

    2003-01-01

    A new thermo-optic fibre switch is demonstrated, which utilizes the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre. We report an extinction ratio of 60 dB and an insertion loss of 1 dB.......A new thermo-optic fibre switch is demonstrated, which utilizes the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre. We report an extinction ratio of 60 dB and an insertion loss of 1 dB....

  20. Theory of circuit block switch-off

    Directory of Open Access Journals (Sweden)

    S. Henzler

    2004-01-01

    Full Text Available Switching-off unused circuit blocks is a promising approach to supress static leakage currents in ultra deep sub-micron CMOS digital systems. Basic performance parameters of Circuit Block Switch-Off (CBSO schemes are defined and their dependence on basic circuit parameters is estimated. Therefore the design trade-off between strong leakage suppression in idle mode and adequate dynamic performance in active mode can be supported by simple analytic investigations. Additionally, a guideline for the estimation of the minimum time for which a block deactivation is useful is derived.