WorldWideScience

Sample records for high bandwidth force

  1. High-bandwidth multimode self-sensing in bimodal atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Michael G. Ruppert

    2016-02-01

    Full Text Available Using standard microelectromechanical system (MEMS processes to coat a microcantilever with a piezoelectric layer results in a versatile transducer with inherent self-sensing capabilities. For applications in multifrequency atomic force microscopy (MF-AFM, we illustrate that a single piezoelectric layer can be simultaneously used for multimode excitation and detection of the cantilever deflection. This is achieved by a charge sensor with a bandwidth of 10 MHz and dual feedthrough cancellation to recover the resonant modes that are heavily buried in feedthrough originating from the piezoelectric capacitance. The setup enables the omission of the commonly used piezoelectric stack actuator and optical beam deflection sensor, alleviating limitations due to distorted frequency responses and instrumentation cost, respectively. The proposed method benefits from a more than two orders of magnitude increase in deflection to strain sensitivity on the fifth eigenmode leading to a remarkable signal-to-noise ratio. Experimental results using bimodal AFM imaging on a two component polymer sample validate that the self-sensing scheme can therefore be used to provide both the feedback signal, for topography imaging on the fundamental mode, and phase imaging on the higher eigenmode.

  2. High-Bandwidth Atomic Force Microscopy Reveals A Mechanical spike Accompanying the Action Potential in mammalian Nerve Terminals

    Science.gov (United States)

    Salzberg, Brian M.

    2008-03-01

    Information transfer from neuron to neuron within nervous systems occurs when the action potential arrives at a nerve terminal and initiates the release of a chemical messenger (neurotransmitter). In the mammalian neurohypophysis (posterior pituitary), large and rapid changes in light scattering accompany secretion of transmitter-like neuropeptides. In the mouse, these intrinsic optical signals are intimately related to the arrival of the action potential (E-wave) and the release of arginine vasopressin and oxytocin (S-wave). We have used a high bandwidth (20 kHz) atomic force microscope (AFM) to demonstrate that these light scattering signals are associated with changes in nerve terminal volume, detected as nanometer-scale movements of a cantilever positioned on top of the neurohypophysis. The most rapid mechanical response, the ``spike'', has duration comparable to that of the action potential (˜2 ms) and probably reflects an increase in terminal volume due to H2O movement associated with Na^+-influx. Elementary calculations suggest that two H2O molecules accompanying each Na^+-ion could account for the ˜0.5-1.0 å increase in the diameter of each terminal during the action potential. Distinguishable from the mechanical ``spike'', a slower mechanical event, the ``dip'', represents a decrease in nerve terminal volume, depends upon Ca^2+-entry, as well as on intra-terminal Ca^2+-transients, and appears to monitor events associated with secretion. A simple hypothesis is that this ``dip'' reflects the extrusion of the dense core granule that comprises the secretory products. These dynamic high bandwidth AFM recordings are the first to monitor mechanical events in nervous systems and may provide novel insights into the mechanism(s) by which excitation is coupled to secretion at nerve terminals.

  3. Network Bandwidth Utilization Forecast Model on High Bandwidth Network

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Wucherl; Sim, Alex

    2014-07-07

    With the increasing number of geographically distributed scientific collaborations and the scale of the data size growth, it has become more challenging for users to achieve the best possible network performance on a shared network. We have developed a forecast model to predict expected bandwidth utilization for high-bandwidth wide area network. The forecast model can improve the efficiency of resource utilization and scheduling data movements on high-bandwidth network to accommodate ever increasing data volume for large-scale scientific data applications. Univariate model is developed with STL and ARIMA on SNMP path utilization data. Compared with traditional approach such as Box-Jenkins methodology, our forecast model reduces computation time by 83.2percent. It also shows resilience against abrupt network usage change. The accuracy of the forecast model is within the standard deviation of the monitored measurements.

  4. High-Bandwidth Hybrid Sensor (HYSENS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ATA has demonstrated the primary innovation of combining a precision MEMS gyro (BAE SiRRS01) with a high bandwidth angular rate sensor, ATA's ARS-14 resulting in a...

  5. High-bandwidth remote flat panel display interconnect system

    Science.gov (United States)

    Peterson, Darrel G.

    1999-08-01

    High performance electronic displays (CRT, AMLCD, TFEL, plasma, etc.) require wide bandwidth electrical drive signals to produce the desired display images. When the image generation and/or image processing circuitry is located within the same line replaceable unit (LRU) as the display media, the transmission of the display drive signals to the display media presents no unusual design problems. However, many aircraft cockpits are severely constrained for available space behind the instrument panel. This often forces the system designer to specify that only the display media and its immediate support circuitry are to be mounted in the instrument panel. A wide bandwidth interconnect system is then required to transfer image data from the display generation circuitry to the display unit. Image data transfer rates of nearly 1.5 Gbits/second may be required when displaying full motion video at a 60 Hz field rate. In addition to wide bandwidth, this interconnect system must exhibit several additional key characteristics: (1) Lossless transmission of image data; (2) High reliability and high integrity; (3) Ease of installation and field maintenance; (4) High immunity to HIRF and electrical noise; (5) Low EMI emissions; (6) Long term supportability; and (7) Low acquisition and maintenance cost. Rockwell Collins has developed an avionics grade remote display interconnect system based on the American National Standards Institute Fibre Channel standard which meets these requirements. Readily available low cost commercial off the shelf (COTS) components are utilized, and qualification tests have confirmed system performance.

  6. VISA IB Ultra-High Bandwidth, High Gain SASE FEL

    CERN Document Server

    Andonian, Gerard; Murokh, Alex; Pellegrini, Claudio; Reiche, Sven; Rosenzweig, J B; Travish, Gil

    2004-01-01

    The results of a high energy-spread SASE FEL experiment, the intermediary experiment linking the VISA I and VISA II projects, are presented. A highly chirped beam (~1.7%) was transported without correction of longitudinal aberrations in the ATF dogleg, and injected into the VISA undulator. The output FEL radiation displayed an uncharacteristicly large bandwidth (~11%) with extremely stable lasing and measured energy of about 2 microJoules. Start-to-end simulations reproduce key features of the measured results and provide an insight into the mechanisms giving rise to such a high bandwidth. These analyses are described as they relate to important considerations for the VISA II experiment.

  7. Fast Faraday Cup With High Bandwidth

    Science.gov (United States)

    Deibele, Craig E [Knoxville, TN

    2006-03-14

    A circuit card stripline Fast Faraday cup quantitatively measures the picosecond time structure of a charged particle beam. The stripline configuration maintains signal integrity, and stitching of the stripline increases the bandwidth. A calibration procedure ensures the measurement of the absolute charge and time structure of the charged particle beam.

  8. On the Bandwidth of High-Impedance Frequency Selective Surfaces

    CERN Document Server

    Costa, Filippo; Monorchio, Agostino; 10.1109/LAWP.2009.2038346

    2010-01-01

    In this letter, the bandwidth of high-impedance surfaces (HISs) is discussed by an equivalent circuit approach. Even if these surfaces have been employed for almost 10 years, it is sometimes unclear how to choose the shape of the frequency selective surface (FSS) on the top of the grounded slab in order to achieve the largest possible bandwidth. Here, we will show that the conventional approach describing the HIS as a parallel connection between the inductance given by the grounded dielectric substrate and the capacitance of the FSS may induce inaccurate results in the determination of the operating bandwidth of the structure. Indeed, in order to derive a more complete model and to provide a more accurate estimate of the operating bandwidth, it is also necessary to introduce the series inductance of the FSS.We will present the explicit expression for defining the bandwidth of a HIS, and we will show that the reduction of the FSS inductance results in the best choice for achieving wide operating bandwidth in c...

  9. High-bandwidth hybrid quantum repeater.

    Science.gov (United States)

    Munro, W J; Van Meter, R; Louis, Sebastien G R; Nemoto, Kae

    2008-07-25

    We present a physical- and link-level design for the creation of entangled pairs to be used in quantum repeater applications where one can control the noise level of the initially distributed pairs. The system can tune dynamically, trading initial fidelity for success probability, from high fidelity pairs (F=0.98 or above) to moderate fidelity pairs. The same physical resources that create the long-distance entanglement are used to implement the local gates required for entanglement purification and swapping, creating a homogeneous repeater architecture. Optimizing the noise properties of the initially distributed pairs significantly improves the rate of generating long-distance Bell pairs. Finally, we discuss the performance trade-off between spatial and temporal resources.

  10. Simple High-Bandwidth Sideband Locking with Heterodyne Readout

    CERN Document Server

    Reinhardt, Christoph; Sankey, Jack C

    2016-01-01

    We present a robust sideband laser locking technique that is ideally suited for applications requiring low probe power and heterodyne readout. By feeding back to a high-bandwidth voltage controlled oscillator, we lock a first-order phase-modulation sideband to a table-top high-finesse Fabry-Perot cavity, achieving a feedback bandwidth of 3.5 MHz with a single integrator, limited fundamentally by the signal delay. The directly measured transfer function of the closed feedback loop agrees with a model assuming ideal system components, and from this we suggest a modified design that should realistically achieve a bandwidth exceeding 6 MHz with a near-causally limited feedback gain of $4\\times 10^7$ at 1 kHz. The off-resonance optical carrier is used for alignment-free heterodyne readout, alleviating the need for a second laser or additional optical modulators.

  11. High Bandwidth Short Stroke Rotary Fast Tool Servo

    Energy Technology Data Exchange (ETDEWEB)

    Montesanti, R C; Trumper, D L

    2003-08-22

    This paper presents the design and performance of a new rotary fast tool servo (FTS) capable of developing the 40 g's tool tip acceleration required to follow a 5 micron PV sinusoidal surface at 2 kHz with a planned accuracy of 50 nm, and having a full stroke of 50 micron PV at lower frequencies. Tests with de-rated power supplies have demonstrated a closed-loop unity-gain bandwidth of 2 kHz with 20 g's tool acceleration, and we expect to achieve 40 g's with supplies providing {+-} 16 Amp to the Lorentz force actuator. The use of a fast tool servo with a diamond turning machine for producing non-axisymmetric or textured surfaces on a workpiece is well known. Our new rotary FTS was designed to specifically accommodate fabricating prescription textured surfaces on 5 mm diameter spherical target components for High Energy Density Physics experiments on the National Ignition Facility Laser (NIF).

  12. High speed and wide bandwidth delta-sigma ADCs

    CERN Document Server

    Bolatkale, Muhammed; Makinwa, Kofi A A

    2014-01-01

    This book describes techniques for realizing wide bandwidth (125MHz) over-sampled analog-to-digital converters (ADCs) in nanometer-CMOS processes.  The authors offer a clear and complete picture of system level challenges and practical design solutions in high-speed Delta-Sigma modulators.  Readers will be enabled to implement ADCs as continuous-time delta-sigma (CT∆Σ) modulators, offering simple resistive inputs, which do not require the use of power-hungry input buffers, as well as offering inherent anti-aliasing, which simplifies system integration. The authors focus on the design of high speed and wide-bandwidth ΔΣMs that make a step in bandwidth range which was previously only possible with Nyquist converters. More specifically, this book describes the stability, power efficiency, and linearity limits of ΔΣMs, aiming at a GHz sampling frequency.   • Provides overview of trends in Wide Bandwidth and High Dynamic Range analog-to-digital converters (ADCs); • Enables the design of a wide band...

  13. Managing high-bandwidth real-time data storage

    Energy Technology Data Exchange (ETDEWEB)

    Bigelow, David D. [Los Alamos National Laboratory; Brandt, Scott A [Los Alamos National Laboratory; Bent, John M [Los Alamos National Laboratory; Chen, Hsing-Bung [Los Alamos National Laboratory

    2009-09-23

    There exist certain systems which generate real-time data at high bandwidth, but do not necessarily require the long-term retention of that data in normal conditions. In some cases, the data may not actually be useful, and in others, there may be too much data to permanently retain in long-term storage whether it is useful or not. However, certain portions of the data may be identified as being vitally important from time to time, and must therefore be retained for further analysis or permanent storage without interrupting the ongoing collection of new data. We have developed a system, Mahanaxar, intended to address this problem. It provides quality of service guarantees for incoming real-time data streams and simultaneous access to already-recorded data on a best-effort basis utilizing any spare bandwidth. It has built in mechanisms for reliability and indexing, can scale upwards to meet increasing bandwidth requirements, and handles both small and large data elements equally well. We will show that a prototype version of this system provides better performance than a flat file (traditional filesystem) based version, particularly with regard to quality of service guarantees and hard real-time requirements.

  14. Ultra-high bandwidth quantum secured data transmission

    Science.gov (United States)

    Dynes, James F.; Tam, Winci W.-S.; Plews, Alan; Fröhlich, Bernd; Sharpe, Andrew W.; Lucamarini, Marco; Yuan, Zhiliang; Radig, Christian; Straw, Andrew; Edwards, Tim; Shields, Andrew J.

    2016-10-01

    Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment.

  15. Ultra-high bandwidth quantum secured data transmission

    Science.gov (United States)

    Dynes, James F.; Tam, Winci W-S.; Plews, Alan; Fröhlich, Bernd; Sharpe, Andrew W.; Lucamarini, Marco; Yuan, Zhiliang; Radig, Christian; Straw, Andrew; Edwards, Tim; Shields, Andrew J.

    2016-01-01

    Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment. PMID:27734921

  16. Modulator-Based, High Bandwidth Optical Links for HEP Experiments

    CERN Document Server

    Underwood, D G; Fernando, W S; Stanek, R W

    2012-01-01

    As a concern with the reliability, bandwidth and mass of future optical links in LHC experiments, we are investigating CW lasers and light modulators as an alternative to VCSELs. These links will be particularly useful if they utilize light modulators which are very small, low power, high bandwidth, and are very radiation hard. We have constructed a test system with 3 such links, each operating at 10 Gb/s. We present the quality of these links (jitter, rise and fall time, BER) and eye mask margins (10GbE) for 3 different types of modulators: LiNbO3-based, InP-based, and Si-based. We present the results of radiation hardness measurements with up to ~1012 protons/cm2 and ~65 krad total ionizing dose (TID), confirming no single event effects (SEE) at 10 Gb/s with either of the 3 types of modulators. These optical links will be an integral part of intelligent tracking systems at various scales from coupled sensors through intra-module and off detector communication. We have used a Si-based photonic transceiver to...

  17. High speed InAs electron avalanche photodiodes overcome the conventional gain-bandwidth product limit.

    Science.gov (United States)

    Marshall, Andrew R J; Ker, Pin Jern; Krysa, Andrey; David, John P R; Tan, Chee Hing

    2011-11-07

    High bandwidth, uncooled, Indium Arsenide (InAs) electron avalanche photodiodes (e-APDs) with unique and highly desirable characteristics are reported. The e-APDs exhibit a 3dB bandwidth of 3.5 GHz which, unlike that of conventional APDs, is shown not to reduce with increasing avalanche gain. Hence these InAs e-APDs demonstrate a characteristic of theoretically ideal electron only APDs, the absence of a gain-bandwidth product limit. This is important because gain-bandwidth products restrict the maximum exploitable gain in all conventional high bandwidth APDs. Non-limiting gain-bandwidth products up to 580 GHz have been measured on these first high bandwidth e-APDs.

  18. Highly efficient frequency conversion with bandwidth compression of quantum light

    Science.gov (United States)

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks. PMID:28134242

  19. Highly efficient frequency conversion with bandwidth compression of quantum light

    Science.gov (United States)

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.

  20. Highly efficient frequency conversion with bandwidth compression of quantum light

    CERN Document Server

    Allgaier, Markus; Sansoni, Linda; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2016-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, since elements based on parametric down-conversion sources, quantum dots, color centres or atoms are fundamentally different in their frequencies and bandwidths. While pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here, we demonstrate an engineered sum-frequency-conversion process in Lithium Niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 75.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.

  1. Effective Actuation: High Bandwidth Actuators and Actuator Scaling Laws

    Science.gov (United States)

    2007-11-02

    piezo elements mounted on structural members and devices that exhibited aeroacoustic resonance. The former type of actuator ( piezo ) was considered...Raman and Kibens (Raman et al. 2000). These experiments involved high-frequency forcing applied to low-speed flows using wedge piezo actuators and... Subharmonic Interaction and Wall Influence," AIAA- 86-1047, May, 1986. Davis, S. A., 2000, "The manipulation of large and small flow structures in single and

  2. An Octave Bandwidth, High PAE, Linear, Class J GaN High Power Amplifier

    Science.gov (United States)

    2012-03-12

    versus the modeled small-signal gain and return loss response of the Class J amplifier using a 45-W CREE GaN HEMT . The amplifier has a gain of 13 to...AFFTC-PA-12055 An Octave Bandwidth, High PAE, Linear, Class J GaN High Power Amplifier Kris Skowronski, Steve Nelson, Rajesh Mongia, Howard...Technical Paper 3. DATES COVERED (From - To) 11/11 – 03/12 (etc.) 4. TITLE AND SUBTITLE An Octave Bandwidth, High PAE, Linear, Class J GaN High

  3. Adaptive slope compensation for high bandwidth digital current mode controller

    DEFF Research Database (Denmark)

    Taeed, Fazel; Nymand, Morten

    2015-01-01

    An adaptive slope compensation method for digital current mode control of dc-dc converters is proposed in this paper. The compensation slope is used for stabilizing the inner current loop in peak current mode control. In this method, the compensation slope is adapted with the variations...... in converter duty cycle. The adaptive slope compensation provides optimum controller operation in term of bandwidth over wide range of operating points. In this paper operation principle of the controller is discussed. The proposed controller is implemented in an FPGA to control a 100 W buck converter...

  4. Ultra-low Noise, High Bandwidth, 1550nm HgCdTe APD Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To meet the demands of future high-capacity free space optical communications links, a high bandwidth, near infrared (NIR), single photon sensitive optoelectronic...

  5. Knee implant imaging at 3 Tesla using high-bandwidth radiofrequency pulses.

    Science.gov (United States)

    Bachschmidt, Theresa J; Sutter, Reto; Jakob, Peter M; Pfirrmann, Christian W A; Nittka, Mathias

    2015-06-01

    To investigate the impact of high-bandwidth radiofrequency (RF) pulses used in turbo spin echo (TSE) sequences or combined with slice encoding for metal artifact correction (SEMAC) on artifact reduction at 3 Tesla in the knee in the presence of metal. Local transmit/receive coils feature increased maximum B1 amplitude, reduced SAR exposition and thus enable the application of high-bandwidth RF pulses. Susceptibility-induced through-plane distortion scales inversely with the RF bandwidth and the view angle, hence blurring, increases for higher RF bandwidths, when SEMAC is used. These effects were assessed for a phantom containing a total knee arthroplasty. TSE and SEMAC sequences with conventional and high RF bandwidths and different contrasts were tested on eight patients with different types of implants. To realize scan times of 7 to 9 min, SEMAC was always applied with eight slice-encoding steps and distortion was rated by two radiologists. A local transmit/receive knee coil enables the use of an RF bandwidth of 4 kHz compared with 850 Hz in conventional sequences. Phantom scans confirm the relation of RF bandwidth and through-plane distortion, which can be reduced up to 79%, and demonstrate the increased blurring for high-bandwidth RF pulses. In average, artifacts in this RF mode are rated hardly visible for patients with joint arthroplasties, when eight SEMAC slice-encoding steps are applied, and for patients with titanium fixtures, when TSE is used. The application of high-bandwidth RF pulses by local transmit coils substantially reduces through-plane distortion artifacts at 3 Tesla. © 2014 Wiley Periodicals, Inc.

  6. Study on Dielectric Resonator Antenna with Annular Patch for High Gain and Large Bandwidth

    Institute of Scientific and Technical Information of China (English)

    FENG Kuisheng; LI Na; MENG Qingwei; WANG Yongfeng; ZHANG Jingwei

    2015-01-01

    A new high-gain cylindrical Dielectric res-onator antenna (DRA) with a large bandwidth is proposed. A cylindrical Dielectric resonator (DR), a double-annular patch and a metallic cylinder are used to obtain a large bandwidth and a high gain. The mode TM12 excited in the patch is used to enhance the gain of the DRA, and the cavity formed by the metallic cylinder provides a further higher gain and a larger bandwidth. The measured results demonstrate that the proposed DRA achieves a large band-width of 23%from 5.3 to 6.8GHz with VSWR less than two and a high gain around 11 dBi.

  7. THE IMPROVEMENT OF COMPUTER NETWORK PERFORMANCE WITH BANDWIDTH MANAGEMENT IN KEMURNIAN II SENIOR HIGH SCHOOL

    Directory of Open Access Journals (Sweden)

    Bayu Kanigoro

    2012-05-01

    Full Text Available This research describes the improvement of computer network performance with bandwidth management in Kemurnian II Senior High School. The main issue of this research is the absence of bandwidth division on computer, which makes user who is downloading data, the provided bandwidth will be absorbed by the user. It leads other users do not get the bandwidth. Besides that, it has been done IP address division on each room, such as computer, teacher and administration room for supporting learning process in Kemurnian II Senior High School, so wireless network is needed. The method is location observation and interview with related parties in Kemurnian II Senior High School, the network analysis has run and designed a new topology network including the wireless network along with its configuration and separation bandwidth on microtic router and its limitation. The result is network traffic on Kemurnian II Senior High School can be shared evenly to each user; IX and IIX traffic are separated, which improve the speed on network access at school and the implementation of wireless network.Keywords: Bandwidth Management; Wireless Network

  8. High modulation bandwidth of a light-emitting diode with surface plasmon coupling (Conference Presentation)

    Science.gov (United States)

    Lin, Chun-Han; Tu, Charng-Gan; Yao, Yu-Feng; Chen, Sheng-Hung; Su, Chia-Ying; Chen, Hao-Tsung; Kiang, Yean-Woei; Yang, Chih-Chung

    2017-02-01

    Besides lighting, LEDs can be used for indoor data transmission. Therefore, a large modulation bandwidth becomes an important target in the development of visible LED. In this regard, enhancing the radiative recombination rate of carriers in the quantum wells of an LED is a useful method since the modulation bandwidth of an LED is related to the carrier decay rate besides the device RC time constant To increase the carrier decay rate in an LED without sacrificing its output power, the technique of surface plasmon (SP) coupling in an LED is useful. In this paper, the increases of modulation bandwidth by reducing mesa size, decreasing active layer thickness, and inducing SP coupling in blue- and green-emitting LEDs are illustrated. The results are demonstrated by comparing three different LED surface structures, including bare p-type surface, GaZnO current spreading layer, and Ag nanoparticles (NPs) for inducing SP coupling. In a single-quantum-well, blue-emitting LED with a circular mesa of 10 microns in radius, SP coupling results in a modulation bandwidth of 528.8 MHz, which is believed to be the record-high level. A smaller RC time constant can lead to a higher modulation bandwidth. However, when the RC time constant is smaller than 0.2 ns, its effect on modulation bandwidth saturates. The dependencies of modulation bandwidth on injected current density and carrier decay time confirm that the modulation bandwidth is essentially inversely proportional to a time constant, which is inversely proportional to the square-root of carrier decay rate and injected current density.

  9. High Speed and Wide Bandwidth Delta-Sigma ADCs

    NARCIS (Netherlands)

    Bolatkale, M.

    2013-01-01

    This thesis describes the theory, design and implementation of a high-speed, high-performance continuous-time delta-sigma (CTΔΣ) ADC for applications such as medical imaging, high-definition video processing, and wireline and wireless communications. In order to achieve a GHz clocking speed, this

  10. High Speed and Wide Bandwidth Delta-Sigma ADCs

    NARCIS (Netherlands)

    Bolatkale, M.

    2013-01-01

    This thesis describes the theory, design and implementation of a high-speed, high-performance continuous-time delta-sigma (CTΔΣ) ADC for applications such as medical imaging, high-definition video processing, and wireline and wireless communications. In order to achieve a GHz clocking speed, this th

  11. Extremelly High Bandwidth Rad Hard Data Acquisition System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Analog-to-digital converters (ADCs) are the key components for digitizing high-speed analog data in modern data acquisition systems, which is a critical part of...

  12. Extremelly High Bandwidth Rad Hard Data Acquisition System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advancements in sensors/detectors are needed to support future NASA mission concepts including polarimetry, large format imaging arrays, and high-sensitivity...

  13. Plasma Sensor for High Bandwidth Mass-Flow Measurements at High Mach Numbers with RF Link Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposal is aimed at the development of a miniature high bandwidth (1 MHz class) plasma sensor for flow measurements at high enthalpies. This device uses a...

  14. High-Bandwidth Tactical-Network Data Analysis in a High-Performance-Computing (HPC) Environment: Device Status Data

    Science.gov (United States)

    2015-09-01

    5.1.1 Basic Components The Hydra data processing framework provides an object - oriented hierarchy for organizing data processing within an HPC...ARL-CR-0780 ● SEP 2015 US Army Research Laboratory High-Bandwidth Tactical-Network Data Analysis in a High-Performance-Computing...ARL-CR-0780 ● SEP 2015 US Army Research Laboratory High-Bandwidth Tactical-Network Data Analysis in a High-Performance-Computing (HPC

  15. Fully Controllable Pancharatnam-Berry Metasurface Array with High Conversion Efficiency and Broad Bandwidth

    Science.gov (United States)

    Liu, Chuanbao; Bai, Yang; Zhao, Qian; Yang, Yihao; Chen, Hongsheng; Zhou, Ji; Qiao, Lijie

    2016-01-01

    Metasurfaces have powerful abilities to manipulate the properties of electromagnetic waves flexibly, especially the modulation of polarization state for both linearly polarized (LP) and circularly polarized (CP) waves. However, the transmission efficiency of cross-polarization conversion by a single-layer metasurface has a low theoretical upper limit of 25% and the bandwidth is usually narrow, which cannot be resolved by their simple additions. Here, we efficiently manipulate polarization coupling in multilayer metasurface to promote the transmission of cross-polarization by Fabry-Perot resonance, so that a high conversion coefficient of 80–90% of CP wave is achieved within a broad bandwidth in the metasurface with C-shaped scatters by theoretical calculation, numerical simulation and experiments. Further, fully controlling Pancharatnam-Berry phase enables to realize polarized beam splitter, which is demonstrated to produce abnormal transmission with high conversion efficiency and broad bandwidth. PMID:27703254

  16. Using the Sirocco File System for high-bandwidth checkpoints.

    Energy Technology Data Exchange (ETDEWEB)

    Klundt, Ruth Ann; Curry, Matthew L.; Ward, H. Lee

    2012-02-01

    The Sirocco File System, a file system for exascale under active development, is designed to allow the storage software to maximize quality of service through increased flexibility and local decision-making. By allowing the storage system to manage a range of storage targets that have varying speeds and capacities, the system can increase the speed and surety of storage to the application. We instrument CTH to use a group of RAM-based Sirocco storage servers allocated within the job as a high-performance storage tier to accept checkpoints, allowing computation to potentially continue asynchronously of checkpoint migration to slower, more permanent storage. The result is a 10-60x speedup in constructing and moving checkpoint data from the compute nodes. This demonstration of early Sirocco functionality shows a significant benefit for a real I/O workload, checkpointing, in a real application, CTH. By running Sirocco storage servers within a job as RAM-only stores, CTH was able to store checkpoints 10-60x faster than storing to PanFS, allowing the job to continue computing sooner. While this prototype did not include automatic data migration, the checkpoint was available to be pushed or pulled to disk-based storage as needed after the compute nodes continued computing. Future developments include the ability to dynamically spawn Sirocco nodes to absorb checkpoints, expanding this mechanism to other fast tiers of storage like flash memory, and sharing of dynamic Sirocco nodes between multiple jobs as needed.

  17. High-gain, high-bandwidth, rail-to-rail, constant-gm CMOS operational amplifier

    Science.gov (United States)

    Huang, Hong-Yi; Wang, Bo-Ruei

    2013-01-01

    This study presents a high-gain, high-bandwidth, constant-gm , rail-to-rail operational amplifier (op-amp). The constant transconductance is improved with a source-to-bulk bias control of an input pair. A source degeneration scheme is also adapted to the output stage for receiving wide input range without degradation of the gain. Additionally, several compensation schemes are employed to enhance the stability. A test chip is fabricated in a 0.18 µm complementary metal-oxide semiconductor process. The active area of the op-amp is 181 × 173 µm2 and it consumes a power of 2.41 mW at a supply voltage of 1.8 V. The op-amp achieves a dc gain of 94.3 dB and a bandwidth of 45 MHz when the output capacitive load is connected to an effective load of 42.5 pF. A class-AB output stage combining a slew rate (SR) boost circuit provides a sinking current of 6 mA and an SR of 17 V/µs.

  18. Full phase stabilization of a Yb:fiber femtosecond frequency comb via high-bandwidth transducers

    NARCIS (Netherlands)

    Benko, C.; Ruehl, A.; Martin, M.J.; Eikema, K.S.E.; Fermann, M.E.; Hartl, I.; Ye, J.

    2012-01-01

    We present full phase stabilization of an amplified Yb:fiber femtosecond frequency comb using an intracavity electro-optic modulator and an acousto-optic modulator. These transducers provide high servo bandwidths of 580 kHz and 250 kHz for f(rep) and f(ceo), producing a robust and low phase noise fi

  19. High Bandwidth Rotary Fast Tool Servos and a Hybrid Rotary/Linear Electromagnetic Actuator

    Energy Technology Data Exchange (ETDEWEB)

    Montesanti, Richard Clement [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2005-09-01

    This thesis describes the development of two high bandwidth short-stroke rotary fast tool servos and the hybrid rotary/linear electromagnetic actuator developed for one of them. Design insights, trade-o® methodologies, and analytical tools are developed for precision mechanical systems, power and signal electronic systems, control systems, normal-stress electromagnetic actuators, and the dynamics of the combined systems.

  20. High-frequency multimodal atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Adrian P. Nievergelt

    2014-12-01

    Full Text Available Multifrequency atomic force microscopy imaging has been recently demonstrated as a powerful technique for quickly obtaining information about the mechanical properties of a sample. Combining this development with recent gains in imaging speed through small cantilevers holds the promise of a convenient, high-speed method for obtaining nanoscale topography as well as mechanical properties. Nevertheless, instrument bandwidth limitations on cantilever excitation and readout have restricted the ability of multifrequency techniques to fully benefit from small cantilevers. We present an approach for cantilever excitation and deflection readout with a bandwidth of 20 MHz, enabling multifrequency techniques extended beyond 2 MHz for obtaining materials contrast in liquid and air, as well as soft imaging of delicate biological samples.

  1. High-resolution and wide-bandwidth light intensity fiber optic displacement sensor for MEMS metrology.

    Science.gov (United States)

    Orłowska, Karolina; Świątkowski, Michał; Kunicki, Piotr; Kopiec, Daniel; Gotszalk, Teodor

    2016-08-01

    We report on the design, properties, and applications of a high-resolution and wide-bandwidth light intensity fiber optic displacement sensor for microelectromechanical system (MEMS) metrology. There are two types of structures that the system is dedicated to: vibrating with both high and low frequencies. In order to ensure high-frequency and high-resolution measurements, frequency down mixing and selective signal processing were applied. The obtained effective measuring bandwidth ranges from single hertz to 1 megahertz. The achieved resolution presented here is 116  pm/Hz1/2 and 138  pm/Hz1/2 for low-frequency and high-frequency operation modes, respectively, whereas the measurement of static displacement is 100 μm.

  2. Pickup design for high bandwidth bunch arrival-time monitors in free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Angelovski, Aleksandar; Penirschke, Andreas; Jakoby, Rolf [TU Darmstadt (Germany). Institut fuer Mikrowellentechnik und Photonik; Kuhl, Alexander; Schnepp, Sascha [TU Darmstadt (Germany). Graduate School of Computational Engineering; Bock, Marie Kristin; Bousonville, Michael; Schlarb, Holger [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Weiland, Thomas [TU Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder

    2012-07-01

    The increased demands for low bunch charge operation mode in the free-electron lasers (FELs) require an upgrade of the existing synchronization equipment. As a part of the laser-based synchronization system, the bunch arrival-time monitors (BAMs) should have a sub-10 femtosecond precision for high and low bunch charge operation. In order to fulfill the resolution demands for both modes of operation, the bandwidth of such a BAM should be increased up to a cutoff frequency of 40 GHz. In this talk, we present the design and the realization of high bandwidth cone-shaped pickup electrodes as a part of the BAM for the FEL in Hamburg (FLASH) and the European X-ray free-electron laser (European XFEL). The proposed pickup was simulated with CST STUDIO SUITE, and a non-hermetic model was built up for radio frequency (rf) measurements.

  3. Bullet: high bandwidth data dissemination using an overlay mesh

    OpenAIRE

    Kostic, D.; Rodriguez, A.; J. Albrecht; Vahdat, A.

    2003-01-01

    In recent years, overlay networks have become an effective alternative to IP multicast for efficient point to multipoint communication across the Internet. Typically, nodes self-organize with the goal of forming an efficient overlay tree, one that meets performance targets without placing undue burden on the underlying network. In this paper, we target high-bandwidth data distribution from a single source to a large number of receivers. Applications include large-file transfers and real-time ...

  4. Automatic high-bandwidth calibration and reconstruction of arbitrarily sampled parallel MRI.

    Directory of Open Access Journals (Sweden)

    Jan Aelterman

    Full Text Available Today, many MRI reconstruction techniques exist for undersampled MRI data. Regularization-based techniques inspired by compressed sensing allow for the reconstruction of undersampled data that would lead to an ill-posed reconstruction problem. Parallel imaging enables the reconstruction of MRI images from undersampled multi-coil data that leads to a well-posed reconstruction problem. Autocalibrating pMRI techniques encompass pMRI techniques where no explicit knowledge of the coil sensivities is required. A first purpose of this paper is to derive a novel autocalibration approach for pMRI that allows for the estimation and use of smooth, but high-bandwidth coil profiles instead of a compactly supported kernel. These high-bandwidth models adhere more accurately to the physics of an antenna system. The second purpose of this paper is to demonstrate the feasibility of a parameter-free reconstruction algorithm that combines autocalibrating pMRI and compressed sensing. Therefore, we present several techniques for automatic parameter estimation in MRI reconstruction. Experiments show that a higher reconstruction accuracy can be had using high-bandwidth coil models and that the automatic parameter choices yield an acceptable result.

  5. High-Bandwidth Dynamic Full-Field Profilometry for Nano-Scale Characterization of MEMS

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L-C [Graduate Institute of Automation Technology, National Taipei University of Technology, 1 Sec. 3 Chung-Hsiao East Rd., Taipei, 106, Taiwan (China); Huang, Y-T [Graduate Institute of Automation Technology, National Taipei University of Technology, 1 Sec. 3 Chung-Hsiao East Rd., Taipei, 106, Taiwan (China); Chang, P-B [Graduate Institute of Mechanical and Electrical Engineering, National Taipei University of Technology, 1 Sec. 3 Chung-Hsiao East Rd., Taipei, 106, Taiwan (China)

    2006-10-15

    The article describes an innovative optical interferometric methodology to delivery dynamic surface profilometry with a measurement bandwidth up to 10MHz or higher and a vertical resolution up to 1 nm. Previous work using stroboscopic microscopic interferometry for dynamic characterization of micro (opto)electromechanical systems (M(O)EMS) has been limited in measurement bandwidth mainly within a couple of MHz. For high resonant mode analysis, the stroboscopic light pulse is insufficiently short to capture the moving fringes from dynamic motion of the detected structure. In view of this need, a microscopic prototype based on white-light stroboscopic interferometry with an innovative light superposition strategy was developed to achieve dynamic full-field profilometry with a high measurement bandwidth up to 10MHz or higher. The system primarily consists of an optical microscope, on which a Mirau interferometric objective embedded with a piezoelectric vertical translator, a high-power LED light module with dual operation modes and light synchronizing electronics unit are integrated. A micro cantilever beam used in AFM was measured to verify the system capability in accurate characterisation of dynamic behaviours of the device. The full-field seventh-mode vibration at a vibratory frequency of 3.7MHz can be fully characterized and nano-scale vertical measurement resolution as well as tens micrometers of vertical measurement range can be performed.

  6. A HIGH BANDWIDTH BIPOLAR POWER SUPPLY FOR THE FAST CORRECTORS IN THE APS UPGRADE*

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ju; Sprau, Gary

    2017-06-25

    The APS Upgrade of a multi-bend achromat (MBA) storage ring requires a fast bipolar power supply for the fast correction magnets. The key performance requirement of the power supply includes a small-signal bandwidth of 10 kHz for the output current. This requirement presents a challenge to the design because of the high inductance of the magnet load and a limited input DC voltage. A prototype DC/DC power supply utilizing a MOSFET H-bridge circuit with a 500 kHz PWM has been developed and tested successfully. The prototype achieved a 10-kHz bandwidth with less than 3-dB attenuation for a signal 0.5% of the maximum operating current of 15 amperes. This paper presents the design of the power circuit, the PWM method, the control loop, and the test results.

  7. High-speed 405-nm superluminescent diode (SLD) with 807-MHz modulation bandwidth

    KAUST Repository

    Shen, Chao

    2016-08-25

    III-nitride LEDs are fundamental components for visible-light communication (VLC). However, the modulation bandwidth is inherently limited by the relatively long carrier lifetime. In this letter, we present the 405 nm emitting superluminescent diode (SLD) with tilted facet design on semipolar GaN substrate, showing a broad emission of ∼9 nm at 20 mW optical power. Owing to the fast recombination (τ<0.35 ns) through the amplified spontaneous emission, the SLD exhibits a significantly large 3-dB bandwidth of 807 MHz. A data rate of 1.3 Gbps with a bit-error rate of 2.9 × 10 was obtained using on-off keying modulation scheme, suggesting the SLD being a high-speed transmitter for VLC applications.

  8. Maximizing the bandwidth of coherent, mid-IR supercontinuum using highly nonlinear aperiodic nanofibers

    Science.gov (United States)

    Baili, Amira; Cherif, Rim; Heidt, Alexander; Zghal, Mourad

    2014-05-01

    We describe in detail a new procedure of maximizing the bandwidth of mid-infrared (mid-IR) supercontinuum (SC) in highly nonlinear microstructured As2Se3 and tellurite aperiodic nanofibers. By introducing aperiodic rings of first and secondary air holes into the cross-sections of our microstructured fiber designs, we achieve flattened and all-normal dispersion profiles over much broader bandwidths than would be possible with simple periodic designs. These fiber designs are optimized for efficient, broadband, and coherent SC generation in the mid-IR spectral region. Numerical simulations show that these designs enable the generation of a SC spanning over 2290 nm extending from 1140 to 3430 nm in 8 cm length of tellurite nanofiber with input energy of E = 200 pJ and a SC bandwidth of over 4700 nm extending from 1795 to 6525 nm generated in only 8 mm-length of As2Se3-based nanofiber with input energy as low as E = 100 pJ. This work provides a new type of broadband mid-IR SC source with flat spectral shape as well as excellent coherence and temporal properties by using aperiodic nanofibers with all-normal dispersion suitable for applications in ultrafast science, metrology, coherent control, non-destructive testing, spectroscopy, and optical coherence tomography in the mid-IR region.

  9. A Synthetic Bandwidth Method for High-Resolution SAR Based on PGA in the Range Dimension

    Directory of Open Access Journals (Sweden)

    Jincheng Li

    2015-06-01

    Full Text Available The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system. There are mainly two challenges in its implementation. The first one is the estimation and compensation of system errors, such as the timing deviation and the amplitude-phase error. Due to precision limitation of the radar instrument, construction of the sub-band signals becomes much more complicated with these errors. The second challenge lies in the combination method, that is how to fit the sub-band signals together into a much wider bandwidth. In this paper, a novel synthetic bandwidth approach is presented. It considers two main errors of the multi-sub-band SAR system and compensates them by a two-order PGA (phase gradient auto-focus-based method, named TRPGA. Furthermore, an improved cut-paste method is proposed to combine the signals in the frequency domain. It exploits the redundancy of errors and requires only a limited amount of data in the azimuth direction for error estimation. Moreover, the up-sampling operation can be avoided in the combination process. Imaging results based on both simulated and real data are presented to validate the proposed approach.

  10. ICE-Based Custom Full-Mesh Network for the CHIME High Bandwidth Radio Astronomy Correlator

    Science.gov (United States)

    Bandura, K.; Cliche, J. F.; Dobbs, M. A.; Gilbert, A. J.; Ittah, D.; Mena Parra, J.; Smecher, G.

    New generation radio interferometers encode signals from thousands of antenna feeds across large bandwidth. Channelizing and correlating this data requires networking capabilities that can handle unprecedented data rates with reasonable cost. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) correlator processes 8-bits from N=2,048 digitizer inputs across 400MHz of bandwidth. Measured in N2× bandwidth, it is the largest radio correlator that is currently commissioning. Its digital back-end must exchange and reorganize the 6.6terabit/s produced by its 128 digitizing and channelizing nodes, and feed it to the 256 graphics processing unit (GPU) node spatial correlator in a way that each node obtains data from all digitizer inputs but across a small fraction of the bandwidth (i.e. ‘corner-turn’). In order to maximize performance and reliability of the corner-turn system while minimizing cost, a custom networking solution has been implemented. The system makes use of Field Programmable Gate Array (FPGA) transceivers to implement direct, passive copper, full-mesh, high speed serial connections between sixteen circuit boards in a crate, to exchange data between crates, and to offload the data to a cluster of 256 GPU nodes using standard 10Gbit/s Ethernet links. The GPU nodes complete the corner-turn by combining data from all crates and then computing visibilities. Eye diagrams and frame error counters confirm error-free operation of the corner-turn network in both the currently operating CHIME Pathfinder telescope (a prototype for the full CHIME telescope) and a representative fraction of the full CHIME hardware providing an end-to-end system validation. An analysis of an equivalent corner-turn system built with Ethernet switches instead of custom passive data links is provided.

  11. Applied Techniques for High Bandwidth Data Transfers across Wide Area Networks

    Institute of Scientific and Technical Information of China (English)

    JasonLee; BillAllcock; 等

    2001-01-01

    Large distributed systems such as Computational/Data Grids require large amounts of data to be co-located with the computing facilities for processing.From our work develogpin a scalable distributed network cache.we have gained experience with techniques necessary to achieve high data throughput over high bandwidth Wide Area Networks(WAN).In this paper,we discuss several hardware and software dsign techniques,and then describe their application to an implementation of an enhanced FTP protocol called GridFTP,We describe results from the Supercomputing 2000 conference.

  12. Designing and implementing Multibeam Smart Antennas for high bandwidth UAV communications using FPGAs

    Science.gov (United States)

    Porcello, J. C.

    Requirements for high bandwidth UAV communications are often necessary in order to move large amounts of mission information to/from Users in real-time. The focus of this paper is antenna beamforming for point-to-point, high bandwidth UAV communications in order to optimize transmit and receive power and support high data throughput communications. Specifically, this paper looks at the design and implementation of Multibeam Smart Antennas to implement antenna beamforming in an aerospace communications environment. The Smart Antenna is contrasted against Fast Fourier Transform (FFT) based beamforming in order to quantify the increase in both computational load and FPGA resources required for multibeam adaptive signal processing in the Smart Antenna. The paper begins with an overall discussion of Smart Antenna design and general beamforming issues in high bandwidth communications. Important design considerations such as processing complexity in a constrained Size, Weight and Power (SWaP) environment are discussed. The focus of the paper is with respect to design and implementation of digital beamforming wideband communications waveforms using FPGAs. A Multibeam Time Delay element is introduced based on Lagrange Interpolation. Design data for Multibeam Smart Antennas in FPGAs is provided in the paper as well as reference circuits for implementation. Finally, an example Multibeam Smart Antenna design is provided based on a Xilinx Virtex-7 FPGA. The Multibeam Smart Antenna example design illustrates the concepts discussed in the paper and provides design insight into Multibeam Smart Antenna implementation from the point of view of implementation complexity, required hardware, and overall system performance gain.

  13. Re-use of Low Bandwidth Equipment for High Bit Rate Transmission Using Signal Slicing Technique

    DEFF Research Database (Denmark)

    Wagner, Christoph; Spolitis, S.; Vegas Olmos, Juan José;

    : Massive fiber-to-the-home network deployment requires never ending equipment upgrades operating at higher bandwidth. We show effective signal slicing method, which can reuse low bandwidth opto-electronical components for optical communications at higher bit rates.......: Massive fiber-to-the-home network deployment requires never ending equipment upgrades operating at higher bandwidth. We show effective signal slicing method, which can reuse low bandwidth opto-electronical components for optical communications at higher bit rates....

  14. Influence of the fiber Bragg gratings with different reflective bandwidths in high power all-fiber laser oscillator

    Science.gov (United States)

    Wang, Jianming; Yan, Dapeng; Xiong, Songsong; Huang, Bao; Li, Cheng

    2017-01-01

    The effects of large-mode-area (LMA) fiber Bragg gratings (FBGs) with different reflective bandwidths on bi-directionally pumped ytterbium-doped single-mode all-fiber laser oscillator have been investigated experimentally. The forward laser output power and the backward signal leakage were measured and analyzed. It was found that the laser output power and efficiency depended on the bandwidth of the high-reflection (HR) FBG used in the laser cavity. The broader bandwidth gives higher laser efficiency, especially at high power level.

  15. Narrow-bandwidth high-order harmonics driven by long-duration hot spots

    Science.gov (United States)

    Kozlov, Maxim; Kfir, Ofer; Fleischer, Avner; Kaplan, Alex; Carmon, Tal; Schwefel, Harald G. L.; Bartal, Guy; Cohen, Oren

    2012-06-01

    We predict and investigate the emission of high-order harmonics by atoms that cross intense laser hot spots that last for a nanosecond or longer. An atom that moves through a nanometer-scale hot spot at characteristic thermal velocity can emit high-order harmonics in a similar fashion to an atom that is irradiated by a short-duration (picosecond-scale) laser pulse. We analyze the collective emission from a thermal gas and from a jet of atoms. In both cases, the line shape of a high-order harmonic exhibits a narrow spike with spectral width that is determined by the bandwidth of the driving laser. Finally, we discuss a scheme for producing long-duration laser hot spots with intensity in the range of the intensity threshold for high-harmonic generation. In the proposed scheme, the hot spot is produced by a long laser pulse that is consecutively coupled to a high-quality micro-resonator and a metallic nano-antenna. This system may be used for generating ultra-narrow bandwidth extreme-ultraviolet radiation through frequency up-conversion of a low-cost compact pump laser.

  16. Three-Axis Attitude Estimation With a High-Bandwidth Angular Rate Sensor

    Science.gov (United States)

    Bayard, David S.; Green, Joseph J.

    2013-01-01

    A continuing challenge for modern instrument pointing control systems is to meet the increasingly stringent pointing performance requirements imposed by emerging advanced scientific, defense, and civilian payloads. Instruments such as adaptive optics telescopes, space interferometers, and optical communications make unprecedented demands on precision pointing capabilities. A cost-effective method was developed for increasing the pointing performance for this class of NASA applications. The solution was to develop an attitude estimator that fuses star tracker and gyro measurements with a high-bandwidth angular rotation sensor (ARS). An ARS is a rate sensor whose bandwidth extends well beyond that of the gyro, typically up to 1,000 Hz or higher. The most promising ARS sensor technology is based on a magnetohydrodynamic concept, and has recently become available commercially. The key idea is that the sensor fusion of the star tracker, gyro, and ARS provides a high-bandwidth attitude estimate suitable for supporting pointing control with a fast-steering mirror or other type of tip/tilt correction for increased performance. The ARS is relatively inexpensive and can be bolted directly next to the gyro and star tracker on the spacecraft bus. The high-bandwidth attitude estimator fuses an ARS sensor with a standard three-axis suite comprised of a gyro and star tracker. The estimation architecture is based on a dual-complementary filter (DCF) structure. The DCF takes a frequency- weighted combination of the sensors such that each sensor is most heavily weighted in a frequency region where it has the lowest noise. An important property of the DCF is that it avoids the need to model disturbance torques in the filter mechanization. This is important because the disturbance torques are generally not known in applications. This property represents an advantage over the prior art because it overcomes a weakness of the Kalman filter that arises when fusing more than one rate

  17. APEnet+: high bandwidth 3D torus direct network for petaflops scale commodity clusters

    Science.gov (United States)

    Ammendola, R.; Biagioni, A.; Frezza, O.; Lo Cicero, F.; Lonardo, A.; Paolucci, P. S.; Rossetti, D.; Salamon, A.; Salina, G.; Simula, F.; Tosoratto, L.; Vicini, P.

    2011-12-01

    We describe herein the APElink+ board, a PCIe interconnect adapter featuring the latest advances in wire speed and interface technology plus hardware support for a RDMA programming model and experimental acceleration of GPU networking; this design allows us to build a low latency, high bandwidth PC cluster, the APEnet+ network, the new generation of our cost-effective, tens-of-thousands-scalable cluster network architecture. Some test results and characterization of data transmission of a complete testbench, based on a commercial development card mounting an Altera® FPGA, are provided.

  18. APEnet+: high bandwidth 3D torus direct network for petaflops scale commodity clusters

    CERN Document Server

    Ammendola, Roberto; Frezza, Ottorino; Cicero, Francesca Lo; Lonardo, Alessandro; Paolucci, Pier Stanislao; Rossetti, Davide; Salamon, Andrea; Salina, Gaetano; Simula, Francesco; Tosoratto, Laura; Vicini, Piero

    2011-01-01

    We describe herein the APElink+ board, a PCIe interconnect adapter featuring the latest advances in wire speed and interface technology plus hardware support for a RDMA programming model and experimental acceleration of GPU networking; this design allows us to build a low latency, high bandwidth PC cluster, the APEnet+ network, the new generation of our cost-effective, tens-of-thousands-scalable cluster network architecture. Some test results and characterization of data transmission of a complete testbench, based on a commercial development card mounting an Altera FPGA, are provided.

  19. Engineering the CernVM-Filesystem as a High Bandwidth Distributed Filesystem for Auxiliary Physics Data

    Science.gov (United States)

    Dykstra, D.; Bockelman, B.; Blomer, J.; Herner, K.; Levshina, T.; Slyz, M.

    2015-12-01

    A common use pattern in the computing models of particle physics experiments is running many distributed applications that read from a shared set of data files. We refer to this data is auxiliary data, to distinguish it from (a) event data from the detector (which tends to be different for every job), and (b) conditions data about the detector (which tends to be the same for each job in a batch of jobs). Relatively speaking, conditions data also tends to be relatively small per job where both event data and auxiliary data are larger per job. Unlike event data, auxiliary data comes from a limited working set of shared files. Since there is spatial locality of the auxiliary data access, the use case appears to be identical to that of the CernVM- Filesystem (CVMFS). However, we show that distributing auxiliary data through CVMFS causes the existing CVMFS infrastructure to perform poorly. We utilize a CVMFS client feature called "alien cache" to cache data on existing local high-bandwidth data servers that were engineered for storing event data. This cache is shared between the worker nodes at a site and replaces caching CVMFS files on both the worker node local disks and on the site's local squids. We have tested this alien cache with the dCache NFSv4.1 interface, Lustre, and the Hadoop Distributed File System (HDFS) FUSE interface, and measured performance. In addition, we use high-bandwidth data servers at central sites to perform the CVMFS Stratum 1 function instead of the low-bandwidth web servers deployed for the CVMFS software distribution function. We have tested this using the dCache HTTP interface. As a result, we have a design for an end-to-end high-bandwidth distributed caching read-only filesystem, using existing client software already widely deployed to grid worker nodes and existing file servers already widely installed at grid sites. Files are published in a central place and are soon available on demand throughout the grid and cached locally on the

  20. Engineering the CernVM-Filesystem as a High Bandwidth Distributed Filesystem for Auxiliary Physics Data

    Energy Technology Data Exchange (ETDEWEB)

    Dykstra, D. [Fermilab; Bockelman, B. [Nebraska U.; Blomer, J. [CERN; Herner, K. [Fermilab; Levshina, T. [Fermilab; Slyz, M. [Fermilab

    2015-12-23

    A common use pattern in the computing models of particle physics experiments is running many distributed applications that read from a shared set of data files. We refer to this data is auxiliary data, to distinguish it from (a) event data from the detector (which tends to be different for every job), and (b) conditions data about the detector (which tends to be the same for each job in a batch of jobs). Relatively speaking, conditions data also tends to be relatively small per job where both event data and auxiliary data are larger per job. Unlike event data, auxiliary data comes from a limited working set of shared files. Since there is spatial locality of the auxiliary data access, the use case appears to be identical to that of the CernVM- Filesystem (CVMFS). However, we show that distributing auxiliary data through CVMFS causes the existing CVMFS infrastructure to perform poorly. We utilize a CVMFS client feature called 'alien cache' to cache data on existing local high-bandwidth data servers that were engineered for storing event data. This cache is shared between the worker nodes at a site and replaces caching CVMFS files on both the worker node local disks and on the site's local squids. We have tested this alien cache with the dCache NFSv4.1 interface, Lustre, and the Hadoop Distributed File System (HDFS) FUSE interface, and measured performance. In addition, we use high-bandwidth data servers at central sites to perform the CVMFS Stratum 1 function instead of the low-bandwidth web servers deployed for the CVMFS software distribution function. We have tested this using the dCache HTTP interface. As a result, we have a design for an end-to-end high-bandwidth distributed caching read-only filesystem, using existing client software already widely deployed to grid worker nodes and existing file servers already widely installed at grid sites. Files are published in a central place and are soon available on demand throughout the grid and cached

  1. Memory bandwidth efficient two-layer reduced-resolution decoding of high-definition video

    Science.gov (United States)

    Comer, Mary L.

    2000-12-01

    This paper addresses the problem of efficiently decoding high- definition (HD) video for display at a reduced resolution. The decoder presented in this paper is intended for applications that are constrained not only in memory size, but also in peak memory bandwidth. This is the case, for example, during decoding of a high-definition television (HDTV) channel for picture-in-picture (PIP) display, if the reduced resolution PIP-channel decoder is sharing memory with the full-resolution main-channel decoder. The most significant source of video quality degradation in a reduced-resolution decoder is prediction drift, which is caused by the mismatch between the full-resolution reference frames used by the encoder and the subsampled reference frames used by the decoder. to mitigate the visually annoying effects of prediction drift, the decoder described in this paper operates at two different resolutions -- a lower resolution for B pictures, which do not contribute to prediction drift and a higher resolution for I and P pictures. This means that the motion-compensation unit (MCU) essentially operates at the higher resolution, but the peak memory bandwidth is the same as that required to decode at the lower resolution. Storage of additional data, representing the higher resolution for I and P pictures, requires a relatively small amount of additional memory as compared to decoding at the lower resolution. Experimental results will demonstrate the improvement in video quality achieved by the addition of the higher-resolution data in forming predictions for P pictures.

  2. Novel high bandwidth wall shear stress sensor for ultrasonic cleaning applications

    Science.gov (United States)

    Gonzalez-Avila, S. Roberto; Prabowo, Firdaus; Ohl, Claus-Dieter

    2010-11-01

    Ultrasonic cleaning is due to the action of cavitation bubbles. The details of the cleaning mechanisms are not revealed or confirmed experimentally, yet several studies suggest that the wall shear stresses generated are very high, i.e. of the order of several thousand Pascal. Ultrasonic cleaning applications span a wide range from semiconductor manufacturing, to low pressure membrane cleaning, and the in the medical field cleaning of surgical instruments. We have developed a novel sensor to monitor and quantify cleaning activity which is (1) very sturdy, (2) has a high bandwidth of several megahertz, (3) is cheap in manufacturing costs, and (4) of very small size. We analyze the sensor signal by comparing its response time correlated to single laser induced cavitation bubbles using high-speed photography. Additionally, we will present first measurements in ultrasonic cleaning bathes using again high-speed photography. A preliminary discussion on the working mechanism of the sensor will be presented.

  3. High-bandwidth squeezed light at 1550 nm from a compact monolithic PPKTP cavity

    CERN Document Server

    Ast, Stefan; Schnabel, Roman

    2013-01-01

    We report the generation of squeezed vacuum states of light at 1550 nm with a broadband quantum noise reduction of up to 4.8 dB ranging from 5 MHz to 1.2 GHz sideband frequency. We used a custom-designed 2.6 mm long biconvex periodically-poled potassium titanyl phosphate (PPKTP) crystal. It featured reflectively coated end surfaces, 2.26 GHz of linewidth and generated the squeezing via optical parametric amplification. Two homodyne detectors with different quantum efficiencies and bandwidths were used to characterize the non-classical noise suppression. We measured squeezing values of up to 4.8 dB from 5 to 100 MHz and up to 3 dB from 100 MHz to 1.2 GHz. The squeezed vacuum measurements were limited by detection loss. We propose an improved detection scheme to measure up to 10 dB squeezing over 1 GHz. Our results of GHz bandwidth squeezed light generation provide new prospects for high-speed quantum key distribution.

  4. Mahanaxar: quality of service guarantees in high-bandwidth, real-time streaming data storage

    Energy Technology Data Exchange (ETDEWEB)

    Bigelow, David [Los Alamos National Laboratory; Bent, John [Los Alamos National Laboratory; Chen, Hsing-Bung [Los Alamos National Laboratory; Brandt, Scott [UCSC

    2010-04-05

    Large radio telescopes, cyber-security systems monitoring real-time network traffic, and others have specialized data storage needs: guaranteed capture of an ultra-high-bandwidth data stream, retention of the data long enough to determine what is 'interesting,' retention of interesting data indefinitely, and concurrent read/write access to determine what data is interesting, without interrupting the ongoing capture of incoming data. Mahanaxar addresses this problem. Mahanaxar guarantees streaming real-time data capture at (nearly) the full rate of the raw device, allows concurrent read and write access to the device on a best-effort basis without interrupting the data capture, and retains data as long as possible given the available storage. It has built in mechanisms for reliability and indexing, can scale to meet arbitrary bandwidth requirements, and handles both small and large data elements equally well. Results from our prototype implementation shows that Mahanaxar provides both better guarantees and better performance than traditional file systems.

  5. High Bandwidth Pickup Design for Bunch Arrival-time Monitors for Free-Electron Laser

    CERN Document Server

    Angelovski, Aleksandar; Hansli, Matthias; Penirschke, Andreas; Schnepp, Sascha M; Bousonville, Michael; Schlarb, Holger; Bock, Marie Kristin; Weiland, Thomas; Jakoby, Rolf

    2012-01-01

    In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor (BAM) designed for high (> 500 pC) and low (20 pC) bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A non-hermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.

  6. High bandwidth pickup design for bunch arrival-time monitors for free-electron laser

    Directory of Open Access Journals (Sweden)

    Aleksandar Angelovski

    2012-11-01

    Full Text Available In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor designed for high (>500  pC and low (20 pC bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A nonhermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.

  7. On Bandwidth Efficient Modulation for High-Data-Rate Wireless LAN Systems

    Directory of Open Access Journals (Sweden)

    Stolpman Victor

    2002-01-01

    Full Text Available We address the problem of high-data-rate orthogonal frequency division multiplexed (OFDM systems under restrictive bandwidth constraints. Based on recent theoretic results, multiple-input multiple-output (MIMO configurations are best suited for this problem. In this paper, we examine several MIMO configurations suitable for high rate transmission. In all scenarios considered, perfect channel state information (CSI is assumed at the receiver. In constrast, availability of CSI at the transmitter is addressed separately. We show that powerful space-time codes can be developed by combining some simple well-known techniques. In fact, we show that for certain configurations, these space-time MIMO configurations are near optimum in terms of outage capacity as compared to previously published codes. Performance evaluation of these techniques is demonstrated within the IEEE 802.11a framework via Monte Carlo simulations.

  8. Applied techniques for high bandwidth data transfers across wide area networks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jason; Gunter, Dan; Tierney, Brian; Allcock, Bill; Bester, Joe; Bresnahan, John; Tuecke, Steve

    2001-04-30

    Large distributed systems such as Computational/Data Grids require large amounts of data to be co-located with the computing facilities for processing. Ensuring that the data is there in time for the computation in today's Internet is a massive problem. From our work developing a scalable distributed network cache, we have gained experience with techniques necessary to achieve high data throughput over high bandwidth Wide Area Networks (WAN). In this paper, we discuss several hardware and software design techniques and issues, and then describe their application to an implementation of an enhanced FTP protocol called GridFTP. We also describe results from two applications using these techniques, which were obtained at the Supercomputing 2000 conference.

  9. High-Bandwidth Photon-Counting Detectors with Enhanced Near-Infrared Response Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Long-range optical telecommunications (LROT) impose challenging requirements on detector array sensitivity at 1064nm and arrays timing bandwidth. Large photonic...

  10. High bandwidth all-optical 3×3 switch based on multimode interference structures

    Science.gov (United States)

    Le, Duy-Tien; Truong, Cao-Dung; Le, Trung-Thanh

    2017-03-01

    A high bandwidth all-optical 3×3 switch based on general interference multimode interference (GI-MMI) structure is proposed in this study. Two 3×3 multimode interference couplers are cascaded to realize an all-optical switch operating at both wavelengths of 1550 nm and 1310 nm. Two nonlinear directional couplers at two outer-arms of the structure are used as all-optical phase shifters to achieve all switching states and to control the switching states. Analytical expressions for switching operation using the transfer matrix method are presented. The beam propagation method (BPM) is used to design and optimize the whole structure. The optimal design of the all-optical phase shifters and 3×3 MMI couplers are carried out to reduce the switching power and loss.

  11. Call Admission Control with Bandwidth Reallocation for Adaptive Multimedia in High-Rate Short-Range Wireless Networks

    Institute of Scientific and Technical Information of China (English)

    ZHAIXuping; BIGuangguo; XUPingping

    2005-01-01

    In high-rate short-range wireless networks,CAC (Call admission control) scheme plays an important role in quality of service provisioning for adaptive multimedia services. Three functions, namely bandwidth satisfaction function, revenue rate function and bandwidth reallocation cost function, are firstly introduced. Based on these functions, an efficient CAC scheme, the Rev-RT-BRA (Reservation-based and Revenue test with Bandwidth reallocation) CAC scheme is proposed. The main idea is that it reserves some bandwidth for service classes with higher admission priority. The performance of the Rev-RT-BRA CAC scheme is analyzed by solving a multidimension Markov process. Both the numerical and simulation results are given. The advantages of the proposedRev-RT-BRA CAC scheme are as follows. (1) It maximizes the overall bandwidth satisfaction function at any system state. (2) It solves the unfairness problem in admitting multiple classes of services with different bandwidth requirenlents. (3) The required admission priority level can be guaranteed for various classes of services.

  12. Tri-material multilayer coatings with high reflectivity and wide bandwidth for 25 to 50 nm extreme ultraviolet light

    Energy Technology Data Exchange (ETDEWEB)

    Aquila, Andrew; Salmassi, Farhad; Liu, Yanwei; Gullikson, Eric M.

    2009-09-09

    Magnesium/silicon carbide (Mg/SiC) multilayers have been fabricated with normal incidence reflectivity in the vicinity of 40% to 50% for wavelengths in the 25 to 50 nm wavelength range. However many applications, for example solar telescopes and ultrafast studies using high harmonic generation sources, desire larger bandwidths than provided by high reflectivity Mg/SiC multilayers. We investigate introducing a third material, Scandium, to create a tri-material Mg/Sc/SiC multilayer allowing an increase the bandwidth while maintaining high reflectivity.

  13. International distance education and the transition from ISDN to high-bandwidth Internet connectivity.

    Science.gov (United States)

    Vincent, Dale S; Berg, Benjamin W; Chitpatima, Suwicha; Hudson, Donald

    2002-12-01

    The Thailand Hawaii Assessment of Interactive Healthcare Initiative (THAI-HI) is an international distance-education project between two teaching hospitals in Honolulu and Bangkok that uses videoconferencing over three ISDN lines. A 'morning report' format is used to discuss clinical cases primarily covering infectious disease and critical-care topics. An audience response system is used at both sites to add interactivity. From July 2001 to May 2002, 816 health-care providers attended 20 clinical conferences. Audiences rated the conferences as highly relevant and as having high training value. Since the ISDN connection is expensive, we plan to convert the telecommunications to a high-bandwidth Internet connection. The Honolulu site will use a 45 Mbit/s commercial connection to the Hawaii Intranetwork Consortium, which links to the Abilene Network on the US mainland. The Bangkok hospital will use a 155 Mbit/s wireless optical connection to UNINET Thailand, which has a 45 Mbit/s circuit to Abilene.

  14. Radiation-tolerant, low-mass, high bandwidth, flexible printed circuit cables for particle physics experiments

    Science.gov (United States)

    McFadden, N. C.; Hoeferkamp, M. R.; Seidel, S.

    2016-09-01

    The design of meter long flexible printed circuit cables required for low-mass ultra-high speed signal transmission in the high radiation environment of the High Luminosity Large Hadron Collider is described. The design geometry is a differential embedded microstrip with 100 Ω nominal impedance. Minimal mass and maximal radiation hardness are pre-eminent considerations. Several dielectric materials are compared. To reduce mass, a cross hatched ground plane is applied. The long flexible printed circuit cables are characterized in bit error rate tests, attenuation versus frequency, mechanical response to temperature induced stress, and dimensional implications on radiation length. These tests are performed before and after irradiation with 1 MeV neutrons to 2×1016/cm2 and 800 MeV protons to 2×1016 1-MeV neutron equivalent/cm2. A 1.0 m Kapton cable with cross hatched ground plane, effective bandwidth of 4.976 gigabits per second, 0.0160% of a radiation length, and no detectable radiation-induced mechanical or electrical degradation is obtained.

  15. Radiation-tolerant, low-mass, high bandwidth, flexible printed circuit cables for particle physics experiments

    Energy Technology Data Exchange (ETDEWEB)

    McFadden, N.C.; Hoeferkamp, M.R.; Seidel, S.

    2016-09-11

    The design of meter long flexible printed circuit cables required for low-mass ultra-high speed signal transmission in the high radiation environment of the High Luminosity Large Hadron Collider is described. The design geometry is a differential embedded microstrip with 100 Ω nominal impedance. Minimal mass and maximal radiation hardness are pre-eminent considerations. Several dielectric materials are compared. To reduce mass, a cross hatched ground plane is applied. The long flexible printed circuit cables are characterized in bit error rate tests, attenuation versus frequency, mechanical response to temperature induced stress, and dimensional implications on radiation length. These tests are performed before and after irradiation with 1 MeV neutrons to 2×10{sup 16}/cm{sup 2} and 800 MeV protons to 2×10{sup 16} 1-MeV neutron equivalent/cm{sup 2}. A 1.0 m Kapton cable with cross hatched ground plane, effective bandwidth of 4.976 gigabits per second, 0.0160% of a radiation length, and no detectable radiation-induced mechanical or electrical degradation is obtained.

  16. Gbps wireless transceivers for high bandwidth interconnections in distributed cyber physical systems

    Science.gov (United States)

    Saponara, Sergio; Neri, Bruno

    2015-05-01

    In Cyber Physical Systems there is a growing use of high speed sensors like photo and video camera, radio and light detection and ranging (Radar/Lidar) sensors. Hence Cyber Physical Systems can benefit from the high communication data rate, several Gbps, that can be provided by mm-wave wireless transceivers. At such high frequency the wavelength is few mm and hence the whole transceiver including the antenna can be integrated in a single chip. To this aim this paper presents the design of 60 GHz transceiver architecture to ensure connection distances up to 10 m and data rate up to 4 Gbps. At 60 GHz there are more than 7 GHz of unlicensed bandwidth (available for free for development of new services). By using a CMOS SOI technology RF, analog and digital baseband circuitry can be integrated in the same chip minimizing noise coupling. Even the antenna is integrated on chip reducing cost and size vs. classic off-chip antenna solutions. Therefore the proposed transceiver can enable at physical layer the implementation of low cost nodes for a Cyber Physical System with data rates of several Gbps and with a communication distance suitable for home/office scenarios, or on-board vehicles such as cars, trains, ships, airplanes

  17. A 750MHz and a 8GHz High Bandwidth Digital FFT Spectrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The scope of this project is to to develop a wide bandwidth, low power, and compact single board digital Fast Fourier Transform spectrometer (FFTS) optimized for the...

  18. High-Bandwidth Photon-Counting Detectors with Enhanced Near-Infrared Response Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Laser optical communications offer the potential to dramatically increase the link bandwidth and decrease the emitter power in long-range space communications....

  19. Design, analysis and testing of a parallel-kinematic high-bandwidth XY nanopositioning stage

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun-Xia; Gu, Guo-Ying; Yang, Mei-Ju; Zhu, Li-Min, E-mail: zhulm@sjtu.edu.cn [State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2013-12-15

    This paper presents the design, analysis, and testing of a parallel-kinematic high-bandwidth XY nanopositioning stage driven by piezoelectric stack actuators. The stage is designed with two kinematic chains. In each kinematic chain, the end-effector of the stage is connected to the base by two symmetrically distributed flexure modules, respectively. Each flexure module comprises a fixed-fixed beam and a parallelogram flexure serving as two orthogonal prismatic joints. With the purpose to achieve high resonance frequencies of the stage, a novel center-thickened beam which has large stiffness is proposed to act as the fixed-fixed beam. The center-thickened beam also contributes to reducing cross-coupling and restricting parasitic motion. To decouple the motion in two axes totally, a symmetric configuration is adopted for the parallelogram flexures. Based on the analytical models established in static and dynamic analysis, the dimensions of the stage are optimized in order to maximize the first resonance frequency. Then finite element analysis is utilized to validate the design and a prototype of the stage is fabricated for performance tests. According to the results of static and dynamic tests, the resonance frequencies of the developed stage are over 13.6 kHz and the workspace is 11.2 μm × 11.6 μm with the cross-coupling between two axes less than 0.52%. It is clearly demonstrated that the developed stage has high resonance frequencies, a relatively large travel range, and nearly decoupled performance between two axes. For high-speed tracking performance tests, an inversion-based feedforward controller is implemented for the stage to compensate for the positioning errors caused by mechanical vibration. The experimental results show that good tracking performance at high speed is achieved, which validates the effectiveness of the developed stage.

  20. Controllable high bandwidth storage of optical information in a Bose-Einstein Condensate

    Science.gov (United States)

    Jayaseelan, Maitreyi; Schultz, Justin T.; Murphree, Joseph D.; Hansen, Azure; Bigelow, Nicholas P.

    2016-05-01

    The storage and retrieval of optical information has been of interest for a variety of applications including quantum information processing, quantum networks and quantum memories. Several schemes have been investigated and realized with weak, narrowband pulses, including techniques using EIT in solid state systems and both hot and cold atomic vapors. In contrast, we investigate the storage and manipulation of strong, high bandwidth pulses in a Bose-Einstein Condensate (BEC) of ultracold 87 Rb atoms. As a storage medium for optical pulses, BECs offer long storage times and preserve the coherence properties of the input information, suppressing unwanted thermal decoherence effects. We present numerical simulations of nanosecond pulses addressing a three-level lambda system on the D2 line of 87 Rb. The signal pulse is stored as a localized spin excitation in the condensate and can be moved or retrieved by reapplication of successive control pulses. The relative Rabi frequencies and areas of the pulses and the local atomic density in the condensate determine the storage location and readout of the signal pulse. Extending this scheme to use beams with a variety of spatial modes such as Hermite- and Laguerre-Gaussian modes offers an expanded alphabet for information storage.

  1. Wide bandwidth optical signals for high range resolution measurements in water

    Science.gov (United States)

    Nash, Justin; Lee, Robert; Mullen, Linda

    2016-05-01

    Measurements with high range resolution are needed to identify underwater threats, especially when two-dimensional contrast information is insufficient to extract object details. The challenge is that optical measurements are limited by scattering phenomena induced by the underwater channel. Back-scatter results in transmitted photons being directed back to the receiver before reaching the target of interest which induces a clutter signal for ranging and a reduction in contrast for imaging. Multiple small-angle scattering (forward-scatter) results in transmitted photons being directed to unintended regions of the target of interest (spatial spreading), while also stretching the temporal profile of a short optical pulse (temporal spreading). Spatial and temporal spreading of the optical signal combine to cause a reduction in range resolution in conventional laser imaging systems. NAVAIR has investigated ways in which wide bandwidth, modulated optical signals can be utilized to improve ranging and imaging performance in turbid water environments. Experimental efforts have been conducted to investigate channel effects on the propagated frequency content, as well as different filtering and processing techniques on the return signals to maximize range resolution. Of particular interest for the modulated pulses are coherent detection and processing techniques employed by the radar community, including methods to reduce sidelobe clutter. This paper will summarize NAVAIR's work and show that wideband optical signals, in combination with the CLEAN algorithm, can indeed provide enhancements to range resolution and 3D imagery in turbid water environments.

  2. Low latency, high bandwidth data communications between compute nodes in a parallel computer

    Science.gov (United States)

    Archer, Charles J.; Blocksome, Michael A.; Ratterman, Joseph D.; Smith, Brian E.

    2010-11-02

    Methods, parallel computers, and computer program products are disclosed for low latency, high bandwidth data communications between compute nodes in a parallel computer. Embodiments include receiving, by an origin direct memory access (`DMA`) engine of an origin compute node, data for transfer to a target compute node; sending, by the origin DMA engine of the origin compute node to a target DMA engine on the target compute node, a request to send (`RTS`) message; transferring, by the origin DMA engine, a predetermined portion of the data to the target compute node using memory FIFO operation; determining, by the origin DMA engine whether an acknowledgement of the RTS message has been received from the target DMA engine; if the an acknowledgement of the RTS message has not been received, transferring, by the origin DMA engine, another predetermined portion of the data to the target compute node using a memory FIFO operation; and if the acknowledgement of the RTS message has been received by the origin DMA engine, transferring, by the origin DMA engine, any remaining portion of the data to the target compute node using a direct put operation.

  3. A Lowpass Filter with Sharp Roll - off and High Relative Stopband Bandwidth Using Asymmetric High - Low Impedance Patches

    Directory of Open Access Journals (Sweden)

    As. Abdipour

    2015-09-01

    Full Text Available In this letter, a microstrip lowpass filter with -3 dB cut-off frequency at 1.286 GHz is proposed. By using two main resonators which are placed symmetrically around Y axis a sharp roll-off rate (250 dB/GHz is obtained. The proposed resonators are consisted of two asymmetric high-low impedance patches. To achieve a high relative stopband bandwidth (1.82 four high - low impedance resonators and four radial stubs as suppressing cells are employed. Furthermore, a flat insertion loss in the passband and a low return loss in the stopband can prove desired in-band and out-band frequency response. The proposed LPF has a high FOM about 63483.

  4. An InP-Based Dual-Depletion-Region Electroabsorption Modulator with Low Capacitance and Predicted High Bandwidth

    Institute of Scientific and Technical Information of China (English)

    SHAO Yong-Bo; ZHAO Ling-Juan; YU Hong-Yan; QIU Ji-Fang; QIU Ying-Ping; PAN Jiao-Qing; WANG Bao-Jun; ZHU Hong-Liang; WANG Wei

    2011-01-01

    A novel dual-depletion-region electroabsorption modulator (DDR-EAM) based on InP at 1550nm is fabricated.The measured capacitance and extinction ratio of the DDR-EAM reveal that the dual depletion region structure can reduce the device capacitance significantly without any degradation of extinction ratio.Moreover,the bandwidth of the DDR-EAM predicted by using an equivalent circuit model is larger than twice the bandwidth of the conventional lumped-electrode EAM (L-EAM).The electroabsorption modulator (EAM) is highly desirable as an external electro-optical modulator due to its high speed,low cost and capability of integration with other optical component such as DFB lasers,DBR lasers or semiconductor optical amplifiers.[1-4]So far,EAMs are typically fabricated by using lumped electrodes[1-4] and travelling-wave electrodes.[5-15]%A novel dual-depletion-region electroabsorption modulator (DDR-EAM) based on InP at 1550nm is fabricated. The measured capacitance and extinction ratio of the DDR-EAM reveal that the dual depletion region structure can reduce the device capacitance significantly without any degradation of extinction ratio. Moreover, the bandwidth of the DDR-EAM predicted by using an equivalent circuit model is larger than twice the bandwidth of the conventional lumped-electrode EAM (L-EAM).

  5. Performance Evaluation of a High Bandwidth Liquid Fuel Modulation Valve for Active Combustion Control

    Science.gov (United States)

    Saus, Joseph R.; DeLaat, John C.; Chang, Clarence T.; Vrnak, Daniel R.

    2012-01-01

    At the NASA Glenn Research Center, a characterization rig was designed and constructed for the purpose of evaluating high bandwidth liquid fuel modulation devices to determine their suitability for active combustion control research. Incorporated into the rig s design are features that approximate conditions similar to those that would be encountered by a candidate device if it were installed on an actual combustion research rig. The characterized dynamic performance measures obtained through testing in the rig are planned to be accurate indicators of expected performance in an actual combustion testing environment. To evaluate how well the characterization rig predicts fuel modulator dynamic performance, characterization rig data was compared with performance data for a fuel modulator candidate when the candidate was in operation during combustion testing. Specifically, the nominal and off-nominal performance data for a magnetostrictive-actuated proportional fuel modulation valve is described. Valve performance data were collected with the characterization rig configured to emulate two different combustion rig fuel feed systems. Fuel mass flows and pressures, fuel feed line lengths, and fuel injector orifice size was approximated in the characterization rig. Valve performance data were also collected with the valve modulating the fuel into the two combustor rigs. Comparison of the predicted and actual valve performance data show that when the valve is operated near its design condition the characterization rig can appropriately predict the installed performance of the valve. Improvements to the characterization rig and accompanying modeling activities are underway to more accurately predict performance, especially for the devices under development to modulate fuel into the much smaller fuel injectors anticipated in future lean-burning low-emissions aircraft engine combustors.

  6. ICE-based Custom Full-Mesh Network for the CHIME High Bandwidth Radio Astronomy Correlator

    CERN Document Server

    Bandura, Kevin; Dobbs, Matt; Gilbert, Adam; Ittah, David; Parra, Juan Mena; Smecher, Graeme

    2016-01-01

    New generation radio interferometers encode signals from thousands of antenna feeds across large bandwidth. Channelizing and correlating this data requires networking capabilities that can handle unprecedented data rates with reasonable cost. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) correlator processes 8-bits from N=2048 digitizer inputs across 400~MHz of bandwidth. Measured in $N^2~\\times $ bandwidth, it is the largest radio correlator that has been built. Its digital back-end must exchange and reorganize the 6.6~terabit/s produced by its 128 digitizing and channelizing nodes, and feed it to the 256-node spatial correlator in a way that each node obtains data from all digitizer inputs but across a small fraction of the bandwidth (i.e. `corner-turn'). In order to maximize performance and reliability of the corner-turn system while minimizing cost, a custom networking solution has been implemented. The system makes use of Field Programmable Gate Array (FPGA) transceivers to implement direct,...

  7. A high performance long-reach passive optical network with a novel excess bandwidth distribution scheme

    Science.gov (United States)

    Chao, I.-Fen; Zhang, Tsung-Min

    2015-06-01

    Long-reach passive optical networks (LR-PONs) have been considered to be promising solutions for future access networks. In this paper, we propose a distributed medium access control (MAC) scheme over an advantageous LR-PON network architecture that reroutes the control information from and back to all ONUs through an (N + 1) × (N + 1) star coupler (SC) deployed near the ONUs, thereby overwhelming the extremely long propagation delay problem in LR-PONs. In the network, the control slot is designed to contain all bandwidth requirements of all ONUs and is in-band time-division-multiplexed with a number of data slots within a cycle. In the proposed MAC scheme, a novel profit-weight-based dynamic bandwidth allocation (P-DBA) scheme is presented. The algorithm is designed to efficiently and fairly distribute the amount of excess bandwidth based on a profit value derived from the excess bandwidth usage of each ONU, which resolves the problems of previously reported DBA schemes that are either unfair or inefficient. The simulation results show that the proposed decentralized algorithms exhibit a nearly three-order-of-magnitude improvement in delay performance compared to the centralized algorithms over LR-PONs. Moreover, the newly proposed P-DBA scheme guarantees low delay performance and fairness even when under attack by the malevolent ONU irrespective of traffic loads and burstiness.

  8. High Speed Peltier Calorimeter for the Calibration of High Bandwidth Power Measurement Equipment

    CERN Document Server

    Frost, Damien F

    2015-01-01

    Accurate power measurements of electronic components operating at high frequencies are vital in determining where power losses occur in a system such as a power converter. Such power measurements must be carried out with equipment that can accurately measure real power at high frequency. We present the design of a high speed calorimeter to address this requirement, capable of reaching a steady state in less than 10 minutes. The system uses Peltier thermoelectric coolers to remove heat generated in a load resistance, and was calibrated against known real power measurements using an artificial neural network. A dead zone controller was used to achieve stable power measurements. The calibration was validated and shown to have an absolute accuracy of +/-8 mW (95% confidence interval) for measurements of real power from 0.1 to 5 W.

  9. Integrated high-speed DFB light source and narrow-bandwidth RCE photodetector for WDM fiber communication network application

    Science.gov (United States)

    Wang, Qiming; Li, Cheng; Pan, Zhong; Luo, Yi

    2000-10-01

    Electroabsorption (EA) modulator integrated with partially gain coupling distributed feedback (DFB) lasers have been fabricated and shown high single mode yield and wavelength stability. The small signal bandwidth is about 7.5 GHz. Strained Si1-xGex/Si multiple quantum well (MQW) resonant-cavity enhanced (RCE) photodetectors with SiO2/Si distributed Bragg reflector (DBR) as the mirrors have been fabricated and shown a clear narrow bandwidth response. The external quantum efficiency at 1.3 micrometer is measured to be about 3.5% under reverse bias of 16 V. A novel GaInNAs/GaAs MQW RCE p-i-n photodetector with high reflectance GaAs/AlAs DBR mirrors has also been demonstrated and shown the selectively detecting function with the FWHM of peak response of 12 nm.

  10. Silicon Photonics for All-Optical Processing and High-Bandwidth-Density Interconnects

    Science.gov (United States)

    Ophir, Noam

    The first chapter of the thesis provides motivation for the integration of silicon photonic modules into compute systems and surveys some of the recent developments in the field. The second chapter then proceeds to detail a technical case study of silicon photonic microring-based WDM links' scalability and power efficiency for these chip I/O applications which could be developed in the intermediate future. The analysis, initiated originally for a workshop on optical and electrical board and rack level interconnects, looks into a detailed model of the optical power budget for such a link capturing both single-channel aspects as well as WDM-operation-related considerations which are unique for a microring physical characteristics. The third chapter, while continuing on the theme silicon photonic high bandwidth density links, proceeds to detail the first experimental demonstration and characterization of an on-chip spatial division multiplexing (SDM) scheme based on microrings for the multiplexing and demultiplexing functionalities. In the context of more forward looking optical network-on-chip environments, SDM-enabled WDM photonic interconnects can potentially achieve superior bandwidth densities per waveguide compared to WDM-only photonic interconnects. The microring-based implementation allows dynamic tuning of the multiplexing and demultiplexing characteristic of the system which allows operation on WDM grid as well device tuning to combat intra-channel crosstalk. The characterization focuses on the first reported power penalty measurements for on-chip silicon photonic SDM link showing minimal penalties achievable with 3 spatial modes concurrently operating on a single waveguide with 10-Gb/s data carried by each mode. The fourth, fifth, and sixth chapters shift in topic from the application of silicon photonics to communication links to the evolving use of silicon waveguides for nonlinear all-optical processing. Chapter four primarily introduces and motivates

  11. A Low Power High Bandwidth Four Quadrant Analog Multiplier in 32 NM CNFET Technology

    Directory of Open Access Journals (Sweden)

    Vitrag Sheth

    2012-05-01

    Full Text Available Carbon Nanotube Field Effect Transistor (CNFET is a promising new technology that overcomes several limitations of traditional silicon integrated circuit technology. In recent years, the potential of CNFET for analog circuit applications has been explored. This paper proposes a novel four quadrant analog multiplier design using CNFETs. The simulation based on 32nm CNFET technology shows that the proposed multiplier has very low harmonic distortion (<0.45%, large input range (±400mV, large bandwidth (~50GHz and low power consumption (~247µW, while operating at a supply voltage of ±0.9V.

  12. Wide-Bandwidth, Wide-Beamwidth, High-Resolution, Millimeter-Wave Imaging for Concealed Weapon Detection

    Energy Technology Data Exchange (ETDEWEB)

    Sheen, David M.; Fernandes, Justin L.; Tedeschi, Jonathan R.; McMakin, Douglas L.; Jones, Anthony M.; Lechelt, Wayne M.; Severtsen, Ronald H.

    2013-06-12

    Active millimeter-wave imaging is currently being used for personnel screening at airports and other high-security facilities. The lateral resolution, depth resolution, clothing penetration, and image illumination quality obtained from next-generation systems can be significantly enhanced through the selection the aperture size, antenna beamwidth, center frequency, and bandwidth. In this paper, the results of an extensive imaging trade study are presented using both planar and cylindrical three-dimensional imaging techniques at frequency ranges of 10-20 GHz, 10 – 40 GHz, 40 – 60 GHz, and 75 – 105 GHz

  13. A Broadband, Spectrally Flat, High Rep-rate Frequency Comb: Bandwidth Scaling and Flatness Enhancement of Phase Modulated CW through Cascaded Four-Wave Mixing

    CERN Document Server

    Supradeepa, V R

    2010-01-01

    We demonstrate a scheme to scale the bandwidth by several times while enhancing spectral flatness of frequency combs generated by intensity and phase modulation of CW lasers using cascaded four-wave mixing in highly nonlinear fiber.

  14. High-bandwidth Modulation of H2/Syngas Fuel to Control Combustion Dynamics in Micro-Mixing Lean Premix Systems

    Energy Technology Data Exchange (ETDEWEB)

    Jeff Melzak; Tim Lieuwen; Adel Mansour

    2012-01-31

    The goal of this program was to develop and demonstrate fuel injection technologies that will facilitate the development of cost-effective turbine engines for Integrated Gasification Combined Cycle (IGCC) power plants, while improving efficiency and reducing emissions. The program involved developing a next-generation multi-point injector with enhanced stability performance for lean premix turbine systems that burn hydrogen (H2) or synthesis gas (syngas) fuels. A previously developed injector that demonstrated superior emissions performance was improved to enhance static flame stability through zone staging and pilot sheltering. In addition, piezo valve technology was implemented to investigate the potential for enhanced dynamic stability through high-bandwidth modulation of the fuel supply. Prototype injector and valve hardware were tested in an atmospheric combustion facility. The program was successful in meeting its objectives. Specifically, the following was accomplished: Demonstrated improvement of lean operability of the Parker multi-point injector through staging of fuel flow and primary zone sheltering; Developed a piezo valve capable of proportional and high-bandwidth modulation of gaseous fuel flow at frequencies as high as 500 Hz; The valve was shown to be capable of effecting changes to flame dynamics, heat release, and acoustic signature of an atmospheric combustor. The latter achievement indicates the viability of the Parker piezo valve technology for use in future adaptively controlled systems for the mitigation of combustion instabilities, particularly for attenuating combustion dynamics under ultra-lean conditions.

  15. High speed single-wavelength modulation and transmission at 2 μm under bandwidth-constrained condition.

    Science.gov (United States)

    Xu, Ke; Wu, Qiong; Xie, Yongqiang; Tang, Ming; Fu, Songnian; Liu, Deming

    2017-02-20

    The 2-μm optical band has gained much attention recently due to its potential applications in optical fiber communication systems. One constraint in this wavelength region is that the electrical bandwidth of components like modulators and photodetectors is limited by the immature manufacturing technologies. Here we experimentally demonstrated the high-speed signal generation and transmission under bandwidth-constrained scenario at 2-μm. It is enabled by the direct-detection optical filter bank multicarrier (FBMC) modulation technique with constant amplitude zero autocorrelation (CAZAC) equalization. We achieved a single wavelength 80 Gbit/s data rate using the 16-QAM FBMC modulation format which is the highest single channel bit rate at 2-μm according to our best knowledge. The signal is transmitted through a 100m-long solid-core fiber designed for single-mode transmission at 2-μm. The measured bit error rates of the signals are below the forward error correction limit of 3.8 × 10-3, and the 100m-fiber transmission brings negligible penalty.

  16. Low-bandwidth authentication.

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, Patrick Joseph; McIver, Lauren; Gaines, Brian R.; Anderson, Erik; Collins, Michael Joseph; Thomas,Kurt Adam; McDaniel, Austin

    2007-09-01

    Remotely-fielded unattended sensor networks generally must operate at very low power--in the milliwatt or microwatt range--and thus have extremely limited communications bandwidth. Such sensors might be asleep most of the time to conserve power, waking only occasionally to transmit a few bits. RFID tags for tracking or material control have similarly tight bandwidth constraints, and emerging nanotechnology devices will be even more limited. Since transmitted data is subject to spoofing, and since sensors might be located in uncontrolled environments vulnerable to physical tampering, the high-consequence data generated by such systems must be protected by cryptographically sound authentication mechanisms; but such mechanisms are often lacking in current sensor networks. One reason for this undesirable situation is that standard authentication methods become impractical or impossible when bandwidth is severely constrained; if messages are small, a standard digital signature or HMAC will be many times larger than the message itself, yet it might be possible to spare only a few extra bits per message for security. Furthermore, the authentication tags themselves are only one part of cryptographic overhead, as key management functions (distributing, changing, and revoking keys) consume still more bandwidth. To address this problem, we have developed algorithms that provide secure authentication while adding very little communication overhead. Such techniques will make it possible to add strong cryptographic guarantees of data integrity to a much wider range of systems.

  17. Low-bandwidth authentication.

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, Patrick Joseph; McIver, Lauren; Gaines, Brian R.; Anderson, Erik; Collins, Michael Joseph; Thomas,Kurt Adam; McDaniel, Austin

    2007-09-01

    Remotely-fielded unattended sensor networks generally must operate at very low power--in the milliwatt or microwatt range--and thus have extremely limited communications bandwidth. Such sensors might be asleep most of the time to conserve power, waking only occasionally to transmit a few bits. RFID tags for tracking or material control have similarly tight bandwidth constraints, and emerging nanotechnology devices will be even more limited. Since transmitted data is subject to spoofing, and since sensors might be located in uncontrolled environments vulnerable to physical tampering, the high-consequence data generated by such systems must be protected by cryptographically sound authentication mechanisms; but such mechanisms are often lacking in current sensor networks. One reason for this undesirable situation is that standard authentication methods become impractical or impossible when bandwidth is severely constrained; if messages are small, a standard digital signature or HMAC will be many times larger than the message itself, yet it might be possible to spare only a few extra bits per message for security. Furthermore, the authentication tags themselves are only one part of cryptographic overhead, as key management functions (distributing, changing, and revoking keys) consume still more bandwidth. To address this problem, we have developed algorithms that provide secure authentication while adding very little communication overhead. Such techniques will make it possible to add strong cryptographic guarantees of data integrity to a much wider range of systems.

  18. Comparison of State-of-the-Art Digital Control and Analogue Control for High Bandwidth Point of Load Converters

    DEFF Research Database (Denmark)

    Jakobsen, Lars Tønnes; Schneider, Henrik; Andersen, Michael Andreas E.

    2008-01-01

    The purpose of this paper is to present a comparison of state-of-the-art digital and analogue control for a Buck converter with synchronous rectification. The digital control scheme is based on a digital self-oscillating modulator that allows the sampling frequency to be higher than the switching...... frequency of the converter. Voltage mode control is used in both the analogue and digital control schemes. The experimental results show that it is possible to design a digitally controlled Buck converter that has the same performance as can be achieved using commercially available analogue control ICs....... The performance of the analogue system can however be increased by using a separate operational amplifier as error amplifier. Thus analogue control is still the best option if high control bandwidth and fast transient response to load steps are important design parameters....

  19. Ultra-low Noise, High Bandwidth, 1550nm HgCdTe APD Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Voxtel Inc. proposes to optimize the design of a large area, 1.55?m sensitive HgCdTe avalanche photodiode (APD) that achieves high gain with nearly no excess noise....

  20. Electrothermal impedance spectroscopy measurement on high power LiMO2/Li4Ti5O12 battery cell with low bandwidth test setup

    DEFF Research Database (Denmark)

    Swierczynski, Maciej Jozef; Stroe, Daniel Loan; Stanciu, Tiberiu

    2015-01-01

    Modern lithium-ion batteries, like LiMO2/Li4Ti5O12 chemistry, are having very high power capability, which drives the need for precise thermal modelling of the battery. Battery thermal models are required to avoid possible safety issues (thermal runaways, high-temperature gradients) but also......-bandwidth and high-current capability for large format battery cells. Thus, this paper evaluates the possibility and accuracy of performing ETIS measurements with a standard battery test station (or bidirectional power supply) with low-bandwidth....

  1. Development of Advanced Low Emission Injectors and High-Bandwidth Fuel Flow Modulation Valves

    Science.gov (United States)

    Mansour, Adel

    2015-01-01

    Parker Hannifin Corporation developed the 3-Zone fuel nozzle for NASA's Environmentally Responsible Aviation Program to meet NASAs target of 75 LTO NOx reduction from CAEP6 regulation. The nozzle concept was envisioned as a drop-in replacement for currently used fuel nozzle stem, and is built up from laminates to provide energetic mixing suitable for lean direct injection mode at high combustor pressure. A high frequency fuel valve was also developed to provide fuel modulation for the pilot injector. Final testing result shows the LTO NOx level falling just shy of NASAs goal at 31.

  2. High Bandwidth Zero Voltage Injection Method for Sensorless Control of PMSM

    DEFF Research Database (Denmark)

    Ge, Xie; Lu, Kaiyuan; Kumar, Dwivedi Sanjeet

    2014-01-01

    High frequency signal injection is widely used in PMSM sensorless control system for low speed operations. The conventional voltage injection method often needs filters to obtain particular harmonic component in order to estimate the rotor position; or it requires several voltage pulses to be inj...... in a fast current regulation performance. Injection of zero voltage also minimizes the inverter voltage error effects caused by the dead-time.......High frequency signal injection is widely used in PMSM sensorless control system for low speed operations. The conventional voltage injection method often needs filters to obtain particular harmonic component in order to estimate the rotor position; or it requires several voltage pulses...... to be injected before the position may be estimated. In this paper, a single pulse zero voltage injection method is proposed. The rotor position is directly estimated from the current ripple at half of the switching frequency. No machine parameters are needed and using of filters is avoided. This results...

  3. Achieving High Resolution Measurements Within Limited Bandwidth Via Sensor Data Compression

    Science.gov (United States)

    2013-06-01

    are buffered separately and then saved when peaks are detected. The data are time stamped and inserted into a first-in, first-out ( FIFO ) buffer...16 samples around the peak are saved. These samples are combined with 2 solar sync words and 2 time stamp words, and are buffered into a FIFO for...Output Frame 5 A/D High Speed Fames Low Speed Fames Solar Buffer Peak Detect Time- Stamped Solar Pulse TX Buffer Solar FIFO

  4. High flux, narrow bandwidth compton light sources via extended laser-electron interactions

    Science.gov (United States)

    Barty, V P

    2015-01-13

    New configurations of lasers and electron beams efficiently and robustly produce high flux beams of bright, tunable, polarized quasi-monoenergetic x-rays and gamma-rays via laser-Compton scattering. Specifically, the use of long-duration, pulsed lasers and closely-spaced, low-charge and low emittance bunches of electron beams increase the spectral flux of the Compton-scattered x-rays and gamma rays, increase efficiency of the laser-electron interaction and significantly reduce the overall complexity of Compton based light sources.

  5. Wide bandwidth and high resolution planar filter array based on DBR-metasurface-DBR structures

    CERN Document Server

    Horie, Yu; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; Faraon, Andrei

    2016-01-01

    We propose and experimentally demonstrate a planar array of optical bandpass filters composed of low loss dielectric metasurface layers sandwiched between two distributed Bragg reflectors (DBRs). The two DBRs form a Fabry-P\\'erot resonator whose center wavelength is controlled by the design of the transmissive metasurface layer which functions as a phase shifting element. We demonstrate an array of bandpass filters with spatially varying center wavelengths covering a wide range of operation wavelengths of 250 nm around {\\lambda} = 1550 nm ({\\Delta}{\\lambda}/{\\lambda} = 16%). The center wavelengths of each filter are independently controlled only by changing the in-plane geometry of the sandwiched metasurfaces, and the experimentally measured quality factors are larger than 700. The demonstrated filter array can be directly integrated on top of photodetector arrays to realize on-chip high-resolution spectrometers with free-space coupling.

  6. Development of Radiation-Tolerant, Low Mass, High Bandwidth Flexible Printed Circuit Cables for Particle Detection Applications

    Science.gov (United States)

    McFadden, Neil

    2016-03-01

    Design options for meter long flexible printed circuit cables required for low mass ultra-high speed signal transmission in the high radiation environment at the High Luminosity run of the Large Hadron Collider (LHC) are described. Two dielectric materials were considered in this study, Kapton and a Kapton/Teflon mixture. The design geometry is a differential embedded microstrip with nominal 100 Ω impedance. Minimal mass and maximal radiation hardness are pre-eminent considerations. The long flexible printed circuit cables are characterized in bit error rate tests (BERT), attenuation versus frequency, mechanical response to stress and temperature change, and RLC decomposition. These tests are performed before and after irradiation with 1 MeV neutrons to 2x1016/cm 2 and 800 MeV protons to 2x1016 1 MeV-neq/cm2. A 1.0 m Kapton cable, with bandwidth of 6.22 gigabits per second, 0.03% of a radiation length, and no radiation induced mechanical or electrical degradation is obtained.

  7. A Novel Multi-carrier Radar for High-speed Wide-bandwidth Stepped-Frequency GPR

    Science.gov (United States)

    Kyoo Kim, Dong; Choi, Young Woo; Kang, Do Wook

    2015-04-01

    Ground Penetrating Radar (GPR) is one of the non-destructive testing methods for studying underground situations by using the electro-magnetic wave radiation effect. Two classical sensing techniques, impulsive GPR and stepped-frequency GPR, are used for a long time in various GPR applications. Signal bandwidths generated by the two techniques ranges from several hundred MHz to several GHz. For the research area of pavement survey the surveying speed is emphasized, thus impulsive GPR has been preferred to stepped-frequency GPR. To make a complete single scan operation, stepped-frequency GPR needs over hundreds of different frequency continuous wave (CW) radiations within its signal bandwidth which is the main time taking process. In case of impulsive GPR, it needs also several repeated pulses, for example from 64 to 512 repeated pulses, to do a complete single scan operation. Although the two techniques need several repeated internal operation processes, impulsive GPR is generally considered to be fast than stepped-frequency GPR. On the other hand, many studies of stepped-frequency GPR emphasizes that high-resolution scanning accuracy can be achieved by controlling each frequency component differently, such as frequency power profile, flexible bandwidth control. In case of pavement survey area, high-accuracy scanning is required within one meter deep as well as high-speed survey. The required accuracy is up to several centimeter in the material where dielectric constant is about 10. When surveying pavement, multi-element array antenna gives advantages to the measurement accuracy enhancement, where the scanning region of a 3 meters wide paved road is divided into several sub-regions as the number of the antenna element. For example, when stepped-frequency GPR requires 6msec for single scan operation and 15-element antenna is considered, the survey speed is limited to 15km/h in order to scan the road every 5cm, which is slow compared with common driving condition on

  8. Level-1 Data Driver Card - A high bandwidth radiation tolerant aggregator board for detectors

    CERN Document Server

    Gkountoumis, Panagiotis; The ATLAS collaboration

    2017-01-01

    The Level-1 Data Driver Card (L1DDC) was designed for the needs of the future upgrades of the innermost stations of the ATLAS end-cap muon spectrometer. The L1DDC is a high speed aggregator board capable of communicating with multiple front-end electronic boards. It collects the Level-1 data along with monitoring data and transmits them to a network interface through bidirectional and/or unidirectional fiber links at 4.8 Gbps each. In addition, the L1DDC board distributes trigger, time and configuration data coming from the network interface to the front-end boards. The L1DDC is fully compatible with the Phase II upgrade where the trigger rate is expected to reach the 1 MHz. Three different types of L1DDC boards will be fabricated handling up to 10.080 Gbps of user data. It consist of custom made radiation tolerant ASICs: the GigaBit Transceiver (GBTx), the FEAST DC-DC converter, the Slow Control Adapter (SCA), and the Versatile Tranceivers (VTRX) and transmitters (VTTX). The overall scheme of the data acquis...

  9. High Bandwidth, Multi-Purpose Passive Radar Receiver Design For Aerospace and Geoscience Targets

    Science.gov (United States)

    Vertatschitsch, Laura

    uninterruptible power supply (UPS) for up to 1 hour of continuous operation. In this document we provide technical details of the hardware, firmware, and software of the system and design strategies and decisions. We cover the topic of coherent processing for passive radar, specifically an overview of the cross-ambiguity function as a detection mechanism. While the applications of a system like this are incredibly broad, the initial validation and performance analysis was applied specifically to detection of aircraft using Digital Television (DTV) broadcast as an illuminator. We present results of both stationary and mobile operation. In stationary operation, the same helicopter has been detected using two different DTV transmissions. Early mobile operation results show the Doppler-spread ground clutter and possible detection of aircraft. In addition to the fully-functional aircraft detection signal chain, alternative FPGA designs are presented with modes for fast sampling on two antennas or four antennas, with access to an aggregate 240 MHz of spectrum, with 8-bit samples. At these extremely high data rates, moderate data loss occurs while saving this data to disk, but as detailed within this document, it can be accounted for and the effects minimalized, still allowing for detection of aircraft. With these modes, FM transmission and DTV transmission can be captured synchronously from a single antenna and digitizer feed, an exciting result that offers promise for both aerospace and geoscience applications.

  10. High-speed atomic force microscopy: imaging and force spectroscopy.

    Science.gov (United States)

    Eghiaian, Frédéric; Rico, Felix; Colom, Adai; Casuso, Ignacio; Scheuring, Simon

    2014-10-01

    Atomic force microscopy (AFM) is the type of scanning probe microscopy that is probably best adapted for imaging biological samples in physiological conditions with submolecular lateral and vertical resolution. In addition, AFM is a method of choice to study the mechanical unfolding of proteins or for cellular force spectroscopy. In spite of 28 years of successful use in biological sciences, AFM is far from enjoying the same popularity as electron and fluorescence microscopy. The advent of high-speed atomic force microscopy (HS-AFM), about 10 years ago, has provided unprecedented insights into the dynamics of membrane proteins and molecular machines from the single-molecule to the cellular level. HS-AFM imaging at nanometer-resolution and sub-second frame rate may open novel research fields depicting dynamic events at the single bio-molecule level. As such, HS-AFM is complementary to other structural and cellular biology techniques, and hopefully will gain acceptance from researchers from various fields. In this review we describe some of the most recent reports of dynamic bio-molecular imaging by HS-AFM, as well as the advent of high-speed force spectroscopy (HS-FS) for single protein unfolding.

  11. Electro-optic prism-pair setup for efficient high bandwidth isochronous CEP phase shift or group delay generation

    Science.gov (United States)

    Gobert, Olivier; Mennerat, Gabriel; Cornaggia, Christian; Lupinski, Dominique; Perdrix, Michel; Guillaumet, Delphine; Lepetit, Fabien; Oksenhendler, Thomas; Comte, Michel

    2016-05-01

    We report the experimental demonstration of an electro-optic prism pair pure carrier-envelope phase (CEP) shifter at low voltage (shift of 1 rad for a voltage of 90 V, applied to a crystal of 5 mm aperture). Validating our mathematical model, the experiments prove that this set-up which uses two rubidium titanyl phosphate (RTP) crystals, can be used either as an efficient high bandwidth CEP shifter without modifying the group delay of an ultrashort pulse (isochronous CEP shifter) or alternatively as a group delay generator with quasi-constant CEP (Pure Group Delay generator). These two configurations which correspond to specific geometries are characterized by spectral interferometry with a 800 nm mode-locked Ti:sapphire laser. The results are in very good agreement with the model. In the pure group delay mode, a group delay of 2.3 fs is obtained at 1000 V/cm without significant CEP shift. In the isochronous mode, a shift of 5.5 rad at 1000 V/cm is generated without significant delay. The applied voltage is also lowered by a factor of nearly three in this configuration, compared to the case of an RTP rectangular slab of the same total length.

  12. Remote, Real-time Investigations of Extreme Environments Using High Power and Bandwidth Cabled Observatories: The OOI Regional Scale Nodes

    Science.gov (United States)

    Kelley, D. S.; Delaney, J. R.

    2012-12-01

    Methane hydrate deposits and hydrothermal vents are two of the most extreme environments on Earth. Seismic events and flow of gases from the seafloor support and modulate novel microbial communities within these systems. Although studied intensely for several decades, significant questions remain about the flux of heat, volatiles and microbial material from the subsurface to the hydrosphere in these dynamic environments. Quantification of microbial communities, their structure and abundances, and metabolic activities is in an infant state. To better understand these systems, the National Science Foundation's Ocean Observatory Initiative has installed high power (8 kW), high bandwidth (10 Gb/s) nodes on the seafloor that provide access to active methane seeps at Southern Hydrate Ridge, and at the most magmatically robust volcano on the Juan de Fuca Ridge - Axial Seamount. The real-time interactive capabilities of the cabled observatory are critical to studying gas-hydrate systems because many of the key processes occur over short time scales. Events such as bubble plume formation, the creation of collapse zones, and increased seepage in response to earthquakes require adaptive response and sampling capabilities. To meet these challenges a suite of instruments will be connected to the cable in 2013. These sensors include full resolution sampling by upward-looking sonars, fluid and gas chemical characterization by mass spectrometers and osmo samplers, long-term duration collection of seep imagery from cameras, and in situ manipulation of chemical sensors coupled with flow meters. In concert, this instrument suite will provide quantification of transient and more stable chemical fluxes. Similarly, at Axial Seamount the high bandwidth and high power fiber optic cables will be used to communicate with and power a diverse array of sensors at the summit of the volcano. Real-time high definition video will provide unprecedented views of macrofaunal and microbial communities

  13. Power spectrum analysis for optical tweezers. II: Laser wavelength dependence of parasitic filtering, and how to achieve high bandwidth

    DEFF Research Database (Denmark)

    Berg-Sørensen, Kirstine; Peterman, Erwin J G; Weber, Tom

    2006-01-01

    In a typical optical tweezers detection system, the position of a trapped object is determined from laser light impinging on a quadrant photodiode. When the laser is infrared and the photodiode is of silicon, they can act together as an unintended low-pass filter. This parasicit effect is due...... this detection system of optical tweezers a bandwidth, accuracy, and precision that are limited only by the data acquisition board's bandwidth and bandpass ripples, here 96.7 kHz and 0.005 dB, respectively. ©2006 American Institute of Physics...

  14. Weak-quasi-bandwidth and forward-bandwidth of graphs

    Institute of Scientific and Technical Information of China (English)

    原晋江

    1996-01-01

    Concepts of weak-quasi-bandwidth and forward-bandwidth of graphs are introduced. They are used to studythe following problems in graph theory: bandwidth, topological bandwidth, fill-in, profile, path-width, tree-width.

  15. Measurement of Metal Cutting Forces at High Speeds

    Science.gov (United States)

    Princehouse, David W.

    1996-03-01

    Proposed numerically-controlled milling machines will cut aluminum alloys with cutter tip speeds of up to 130 m/s (300 MPH). There are a variety of challenging technical problems to be solved--high power density motors, inverters, cutter/machine dynamics, servo control systems--and compelling reasons to do so. We measured time-varying cutting forces at these tip speeds with a 25.4-cm (10-in) diameter cutter turning at rates up to 167 Hz (10,000 RPM.) We took special care to measure and compensate for the dynamic response of the force transducer (a three-axis quartz-crystal milling dynamometer), extending the useful bandwidth of the measurements well into the mechanical resonances of the dynamometer. We instrumented a production milling machine on the factory floor and processed megabytes of data, obtaining results minutes after a cut was made. This case study shows how a physicist's background in mechanics, instrumentation, signal processing, and computing hardware and software can help advance the state of the art in aerospace manufacturing.

  16. Soft Pneumatic Actuator Fascicles for High Force and Reliability

    Science.gov (United States)

    Robertson, Matthew A.; Sadeghi, Hamed; Florez, Juan Manuel

    2017-01-01

    Abstract Soft pneumatic actuators (SPAs) are found in mobile robots, assistive wearable devices, and rehabilitative technologies. While soft actuators have been one of the most crucial elements of technology leading the development of the soft robotics field, they fall short of force output and bandwidth requirements for many tasks. In addition, other general problems remain open, including robustness, controllability, and repeatability. The SPA-pack architecture presented here aims to satisfy these standards of reliability crucial to the field of soft robotics, while also improving the basic performance capabilities of SPAs by borrowing advantages leveraged ubiquitously in biology; namely, the structured parallel arrangement of lower power actuators to form the basis of a larger and more powerful actuator module. An SPA-pack module consisting of a number of smaller SPAs will be studied using an analytical model and physical prototype. Experimental measurements show an SPA pack to generate over 112 N linear force, while the model indicates the benefit of parallel actuator grouping over a geometrically equivalent single SPA scale as an increasing function of the number of individual actuators in the group. For a module of four actuators, a 23% increase in force production over a volumetrically equivalent single SPA is predicted and validated, while further gains appear possible up to 50%. These findings affirm the advantage of utilizing a fascicle structure for high-performance soft robotic applications over existing monolithic SPA designs. An example of high-performance soft robotic platform will be presented to demonstrate the capability of SPA-pack modules in a complete and functional system. PMID:28289573

  17. High power, picosecond green laser based on a frequency-doubled, all-fiber, narrow-bandwidth, linearly polarized, Yb-doped fiber laser

    Science.gov (United States)

    Tian, Wenyan; Isyanova, Yelena; Stegeman, Robert; Huang, Ye; Chieffo, Logan R.; Moulton, Peter F.

    2016-03-01

    We report on the development of an all-fiber, 68-kW-peak-power, 16-ps-pulse-width, narrow-bandwidth, linearly polarized, 1064-nm fiber laser suitable for high-power, picosecond-pulse-width, green-light generation. Our 1064-nm fiber laser delivered an average power of up to 110 W at a repetition of 100- MHz in a narrow bandwidth, with minimal nonlinear distortion. We developed a high-power, picosecond green source at 532 nm through use of single-pass frequency-doubling of our 1064-nm fiber laser in lithium triborate (LBO). Using a 15-mm long LBO crystal, we have generated 30 W of average power in the second harmonic with 73-W of fundamental average power, for a conversion efficiency of 41%.

  18. High-resolution traction force microscopy.

    Science.gov (United States)

    Plotnikov, Sergey V; Sabass, Benedikt; Schwarz, Ulrich S; Waterman, Clare M

    2014-01-01

    Cellular forces generated by the actomyosin cytoskeleton and transmitted to the extracellular matrix (ECM) through discrete, integrin-based protein assemblies, that is, focal adhesions, are critical to developmental morphogenesis and tissue homeostasis, as well as disease progression in cancer. However, quantitative mapping of these forces has been difficult since there has been no experimental technique to visualize nanonewton forces at submicrometer spatial resolution. Here, we provide detailed protocols for measuring cellular forces exerted on two-dimensional elastic substrates with a high-resolution traction force microscopy (TFM) method. We describe fabrication of polyacrylamide substrates labeled with multiple colors of fiducial markers, functionalization of the substrates with ECM proteins, setting up the experiment, and imaging procedures. In addition, we provide the theoretical background of traction reconstruction and experimental considerations important to design a high-resolution TFM experiment. We describe the implementation of a new algorithm for processing of images of fiducial markers that are taken below the surface of the substrate, which significantly improves data quality. We demonstrate the application of the algorithm and explain how to choose a regularization parameter for suppression of the measurement error. A brief discussion of different ways to visualize and analyze the results serves to illustrate possible uses of high-resolution TFM in biomedical research. © 2014 Elsevier Inc. All rights reserved.

  19. High-Power and High-Efficiency 1.3- µm Superluminescent Diode With Flat-Top and Ultrawide Emission Bandwidth

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2015-02-01

    We report on a flat-top and ultrawide emission bandwidth of 125 nm from InGaAsP/InP multiple quantum-well (MQW) superluminescent diode with antireflection coated and tilted ridge-waveguide device configuration. A total output power in excess of 70 mW with an average power spectral density of 0.56 mW/nm and spectral ripple ≤ 1.2 ± 0.5 dB is measured from the device. Wall-plug efficiency and output power as high as 14% and 80 mW, respectively, is demonstrated from this batch of devices. We attribute the broad emission to the inherent inhomogeneity of the electron-heavy-hole (e-hh) and electron-light-hole (e-lh) recombination of the ground state and the first excited state of the MQWs and their simultaneous emission.

  20. Optimization of Quantum-Dot Molecular Beam Epitaxy for Broad Spectral Bandwidth Devices

    KAUST Repository

    Majid, M. A.

    2012-12-01

    The optimization of the key growth parameters for broad spectral bandwidth devices based on quantum dots is reported. A combination of atomic force microscopy, photoluminescence of test samples, and optoelectronic characterization of superluminescent diodes (SLDs) is used to optimize the growth conditions to obtain high-quality devices with large spectral bandwidth, radiative efficiency (due to a reduced defective-dot density), and thus output power. The defective-dot density is highlighted as being responsible for the degradation of device performance. An SLD device with 160 nm of bandwidth centered at 1230 nm is demonstrated.

  1. Novel high-gain, improved-bandwidth, finned-ladder V-band Traveling-Wave Tube slow-wave circuit design

    Science.gov (United States)

    Kory, Carol L.; Wilson, Jeffrey D.

    1994-01-01

    The V-band frequency range of 59-64 GHz is a region of the millimeter-wave spectrum that has been designated for inter-satellite communications. As a first effort to develop a high-efficiency V-band Traveling-Wave Tube (TWT), variations on a ring-plane slow-wave circuit were computationally investigated to develop an alternative to the more conventional ferruled coupled-cavity circuit. The ring-plane circuit was chosen because of its high interaction impedance, large beam aperture, and excellent thermal dissipation properties. Despite these advantages, however, low bandwidth and high voltage requirements have, until now, prevented its acceptance outside the laboratory. In this paper, the three-dimensional electrodynamic simulation code MAFIA (solution of MAxwell's Equation by the Finite-Integration-Algorithm) is used to investigate methods of increasing the bandwidth and lowering the operating voltage of the ring-plane circuit. Calculations of frequency-phase dispersion, beam on-axis interaction impedance, attenuation and small-signal gain per wavelength were performed for various geometric variations and loading distributions of the ring-plane TWT slow-wave circuit. Based on the results of the variations, a circuit termed the finned-ladder TWT slow-wave circuit was designed and is compared here to the scaled prototype ring-plane and a conventional ferruled coupled-cavity TWT circuit over the V-band frequency range. The simulation results indicate that this circuit has a much higher gain, significantly wider bandwidth, and a much lower voltage requirement than the scaled ring-plane prototype circuit, while retaining its excellent thermal dissipation properties. The finned-ladder circuit has a much larger small-signal gain per wavelength than the ferruled coupled-cavity circuit, but with a moderate sacrifice in bandwidth.

  2. Minimization of the impact of a broad bandwidth high-gain nonlinear preamplifier to the amplified spontaneous emission pedestal of the Vulcan petawatt laser facility.

    Science.gov (United States)

    Musgrave, I O; Hernandez-Gomez, C; Canny, D; Collier, J; Heathcote, R

    2007-10-01

    To generate petawatt pulses using the Vulcan Nd:glass laser requires a broad bandwidth high-gain preamplifier. The preamplifier used is an optical parametric amplifier that provides a total gain of 10(8) in three amplification stages. We report on a detailed investigation of the effect of the Vulcan optical parametric chirped pulse amplification (OPCPA) preamplifier on contrast caused by the amplified spontaneous emission (ASE) pedestal that extends up to 2 ns before the arrival of the main pulse. The contrast after compression is improved to 4x10(8) of the intensity of the main pulse using near-field apertures between the stages of the OPCPA preamplifier. Further reduction of the level of the ASE pedestal can be achieved at the cost of a reduction in amplified bandwidth by solely phosphate glass amplification after initial preamplification rather than a mixed glass amplification scheme.

  3. High-Bandwidth Tactical-Network Data Analysis in a High-Performance-Computing (HPC) Environment: Time Tagging the Data

    Science.gov (United States)

    2015-09-01

    1 ms. 15. SUBJECT TERMS tactical networks, data reduction, high-performance computing, data analysis, big data 16. SECURITY CLASSIFICATION OF...study of WIN-T IOTE ClockModel Issues.7 Fig. 5 Sample long-running ADMAS clock differences (3 clock model states...of the total cuts recorded (on the order of 0.00001% of cuts recorded). 7. Adametz J, McGowan J. Case study of WIN-T IOTE ClockModel issues

  4. High-Bandwidth Tactical-Network Data Analysis in a High-Performance-Computing (HPC) Environment: Introduction

    Science.gov (United States)

    2015-09-01

    ability to transport voice and data messages, with high assurance and minimal delays, as the unit maneuvers to accomplish its mission. Tactical...critical to such analysis efforts, in addition to metrics drawn from application-level interactions, such as Voice over futemet Protocol (VoiP...Network Performance Statistics. These provide information on the state of IP routing tables and radio-level connections, which informs the overall

  5. Generation of a spectrum with high flatness and high bandwidth in a short length of telecom fiber using microchip laser

    Science.gov (United States)

    Hernandez-Garcia, J. C.; Estudillo-Ayala, J. M.; Pottiez, O.; Rojas-Laguna, R.; Mata-Chavez, R. I.; Gonzalez-Garcia, A.

    2013-04-01

    In this work, we studied experimentally the generation of a supercontinuum spectrum induced in a piece of standard single-mode fiber using pulses from a microchip laser. For different values of fiber length, we obtained spectra with high flatness in visible and IR regions. The possibility to generate a spectrum with a high flatness and spectral width of more than ˜1100 nm (600 nm to over 1700 nm) in relatively short lengths of telecom fiber (˜57 m), using as the pump pulses with no more than a few kW peak power at a non-zero-dispersion wavelength, is attributed to the peculiar properties of the pulses generated by the pump source. The physical processes leading to the formation of the supercontinuum spectrum were studied by monitoring the growth of the spectrum while increasing the input power. The coupling efficiency between the microchip laser and the telecom fiber helped us obtain a very wide spectrum. This work shows that the use of conventional fiber for supercontinuum generation can be viewed as a cheap and efficient option, in particular for applications like optical metrology, coherence tomography and low noise sources for the characterization of devices.

  6. A miniaturized, high frequency mechanical scanner for high speed atomic force microscope using suspension on dynamically determined points

    NARCIS (Netherlands)

    Herfst, R.W.; Dekker, A.; Witvoet, G.; Crowcombe, W.E.; Lange, T.J. de; Sadeghian Marnani, H.

    2015-01-01

    One of the major limitations in the speed of the atomic force microscope (AFM) is the bandwidth of the mechanical scanning stage, especially in the vertical (z) direction. According to the design principles of “light and stiff” and “static determinacy,” the bandwidth of the mechanical scanner is

  7. A miniaturized, high frequency mechanical scanner for high speed atomic force microscope using suspension on dynamically determined points

    NARCIS (Netherlands)

    Herfst, R.W.; Dekker, A.; Witvoet, G.; Crowcombe, W.E.; Lange, T.J. de; Sadeghian Marnani, H.

    2015-01-01

    One of the major limitations in the speed of the atomic force microscope (AFM) is the bandwidth of the mechanical scanning stage, especially in the vertical (z) direction. According to the design principles of “light and stiff” and “static determinacy,” the bandwidth of the mechanical scanner is lim

  8. Laser damage comparisons of broad-bandwidth, high-reflection optical coatings containing TiO2, Nb2O5, or Ta2O5 high-index layers

    Science.gov (United States)

    Field, Ella S.; Bellum, John C.; Kletecka, Damon E.

    2017-01-01

    Broad bandwidth coatings allow angle of incidence flexibility and accommodate spectral shifts due to aging and water absorption. Higher refractive index materials in optical coatings, such as TiO2, Nb2O5, and Ta2O5, can be used to achieve broader bandwidths compared to coatings that contain HfO2 high index layers. We have identified the deposition settings that lead to the highest index, lowest absorption layers of TiO2, Nb2O5, and Ta2O5, via e-beam evaporation using ion-assisted deposition. We paired these high index materials with SiO2 as the low index material to create broad bandwidth high reflection coatings centered at 1054 nm for 45 deg angle of incidence and P polarization. High reflection bandwidths as large as 231 nm were realized. Laser damage tests of these coatings using the ISO 11254 and NIF-MEL protocols are presented, which revealed that the Ta2O5/SiO2 coating exhibits the highest resistance to laser damage, at the expense of lower bandwidth compared to the TiO2/SiO2 and Nb2O5/SiO2 coatings.

  9. A miniaturized, high frequency mechanical scanner for high speed atomic force microscope using suspension on dynamically determined points

    Energy Technology Data Exchange (ETDEWEB)

    Herfst, Rodolf; Dekker, Bert; Witvoet, Gert; Crowcombe, Will; Lange, Dorus de [Department of Optomechatronics, Netherlands Organization for Applied Scientific Research, TNO, Delft (Netherlands); Sadeghian, Hamed, E-mail: hamed.sadeghianmarnani@tno.nl, E-mail: h.sadeghianmarnani@tudelft.nl [Department of Optomechatronics, Netherlands Organization for Applied Scientific Research, TNO, Delft (Netherlands); Department of Precision and Microsystems Engineering, Delft University of Technology, Delft (Netherlands)

    2015-11-15

    One of the major limitations in the speed of the atomic force microscope (AFM) is the bandwidth of the mechanical scanning stage, especially in the vertical (z) direction. According to the design principles of “light and stiff” and “static determinacy,” the bandwidth of the mechanical scanner is limited by the first eigenfrequency of the AFM head in case of tip scanning and by the sample stage in terms of sample scanning. Due to stringent requirements of the system, simply pushing the first eigenfrequency to an ever higher value has reached its limitation. We have developed a miniaturized, high speed AFM scanner in which the dynamics of the z-scanning stage are made insensitive to its surrounding dynamics via suspension of it on specific dynamically determined points. This resulted in a mechanical bandwidth as high as that of the z-actuator (50 kHz) while remaining insensitive to the dynamics of its base and surroundings. The scanner allows a practical z scan range of 2.1 μm. We have demonstrated the applicability of the scanner to the high speed scanning of nanostructures.

  10. A miniaturized, high frequency mechanical scanner for high speed atomic force microscope using suspension on dynamically determined points.

    Science.gov (United States)

    Herfst, Rodolf; Dekker, Bert; Witvoet, Gert; Crowcombe, Will; de Lange, Dorus; Sadeghian, Hamed

    2015-11-01

    One of the major limitations in the speed of the atomic force microscope (AFM) is the bandwidth of the mechanical scanning stage, especially in the vertical (z) direction. According to the design principles of "light and stiff" and "static determinacy," the bandwidth of the mechanical scanner is limited by the first eigenfrequency of the AFM head in case of tip scanning and by the sample stage in terms of sample scanning. Due to stringent requirements of the system, simply pushing the first eigenfrequency to an ever higher value has reached its limitation. We have developed a miniaturized, high speed AFM scanner in which the dynamics of the z-scanning stage are made insensitive to its surrounding dynamics via suspension of it on specific dynamically determined points. This resulted in a mechanical bandwidth as high as that of the z-actuator (50 kHz) while remaining insensitive to the dynamics of its base and surroundings. The scanner allows a practical z scan range of 2.1 μm. We have demonstrated the applicability of the scanner to the high speed scanning of nanostructures.

  11. Chemical Industry Bandwidth Study

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2006-12-01

    The Chemical Bandwidth Study provides a snapshot of potentially recoverable energy losses during chemical manufacturing. The advantage of this study is the use of "exergy" analysis as a tool for pinpointing inefficiencies.

  12. Bandwidth efficient coding

    CERN Document Server

    Anderson, John B

    2017-01-01

    Bandwidth Efficient Coding addresses the major challenge in communication engineering today: how to communicate more bits of information in the same radio spectrum. Energy and bandwidth are needed to transmit bits, and bandwidth affects capacity the most. Methods have been developed that are ten times as energy efficient at a given bandwidth consumption as simple methods. These employ signals with very complex patterns and are called "coding" solutions. The book begins with classical theory before introducing new techniques that combine older methods of error correction coding and radio transmission in order to create narrowband methods that are as efficient in both spectrum and energy as nature allows. Other topics covered include modulation techniques such as CPM, coded QAM and pulse design.

  13. Industrial Glass Bandwidth Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rue, David M. [Gas Technology Inst., Des Plaines, IL (United States); Servaites, James [Gas Technology Inst., Des Plaines, IL (United States); Wolf, Warren [Gas Technology Inst., Des Plaines, IL (United States)

    2007-08-01

    This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

  14. Glass Industry Bandwidth Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rue, David M. [Gas Technology Inst., Des Plaines, IL (United States)

    2006-07-01

    This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

  15. Industrial Glass Bandwidth Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rue, David M. [Gas Technology Inst., Des Plaines, IL (United States); Servaites, James [Gas Technology Inst., Des Plaines, IL (United States); Wolf, Warren [Gas Technology Inst., Des Plaines, IL (United States)

    2007-08-01

    This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

  16. Glass Industry Bandwidth Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rue, David M. [Gas Technology Inst., Des Plaines, IL (United States)

    2006-07-01

    This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

  17. Bandwidth challenge teams at SC2003 conference

    CERN Multimedia

    2003-01-01

    Results from the fourth annual High-Performance Bandwidth Challenge, held in conjunction with SC2003, the international conference on high-performance computing and networking which occurred last week in Phoenix, AZ (1 page).

  18. Bandwidth Reconfigurable Metamaterial Arrays

    Directory of Open Access Journals (Sweden)

    Nathanael J. Smith

    2014-01-01

    Full Text Available Metamaterial structures provide innovative ways to manipulate electromagnetic wave responses to realize new applications. This paper presents a conformal wideband metamaterial array that achieves as much as 10 : 1 continuous bandwidth. This was done by using interelement coupling to concurrently achieve significant wave slow-down and cancel the inductance stemming from the ground plane. The corresponding equivalent circuit of the resulting array is the same as that of classic metamaterial structures. In this paper, we present a wideband Marchand-type balun with validation measurements demonstrating the metamaterial (MTM array’s bandwidth from 280 MHz to 2800 MHz. Bandwidth reconfiguration of this class of array is then demonstrated achieving a variety of band-pass or band-rejection responses within its original bandwidth. In contrast with previous bandwidth and frequency response reconfigurations, our approach does not change the aperture’s or ground plane’s geometry, nor does it introduce external filtering structures. Instead, the new responses are realized by making simple circuit changes into the balanced feed integrated with the wideband MTM array. A variety of circuit changes can be employed using MEMS switches or variable lumped loads within the feed and 5 example band-pass and band-rejection responses are presented. These demonstrate the potential of the MTM array’s reconfiguration to address a variety of responses.

  19. Remote Robot Control With High Force-Feedback Gain

    Science.gov (United States)

    Kim, Won S.

    1993-01-01

    Improved scheme for force-reflecting hand control of remote robotic manipulator provides unprecedently high force-reflection gain, even when dissimilar master and slave arms used. Three feedback loops contained in remote robot control system exerting position-error-based force feedback and compliance control. Outputs of force and torque sensors on robot not used directly for force reflection, but for compliance control, while errors in position used to generate reflected forces.

  20. High-resolution noncontact atomic force microscopy.

    Science.gov (United States)

    Pérez, Rubén; García, Ricardo; Schwarz, Udo

    2009-07-01

    original papers authored by many of the leading groups in the field with the goal of providing a well-balanced overview on the state-of-the-art in this rapidly evolving field. These papers, many of which are based on notable presentations given during the Madrid conference, feature highlights such as (1) the development of sophisticated force spectroscopy procedures that are able to map the complete 3D tip-sample force field on different surfaces; (2) the considerable resolution improvement of Kelvin probe force microscopy (reaching, in some cases, the atomic scale), which is accompanied by a thorough, quantitative understanding of the contrast observed; (3) the perfecting of atomic resolution imaging on insulating substrates, which helps reshape our microscopic understanding of surface properties and chemical activity of these surfaces; (4) the description of instrumental and methodological developments that pave the way to the atomic-scale characterization of magnetic and electronic properties of nanostructures, and last but not least (5) the extension of dynamic imaging modes to high-resolution operation in liquids, ultimately achieving atomic resolution. The latter developments are already having a significant impact in the highly competitive field of biological imaging under physiological conditions. This special issue of Nanotechnology would not have been possible without the highly professional support from Nina Couzin, Amy Harvey, Alex Wotherspoon and the entire Nanotechnology team at IOP Publishing. We are thankful for their help in pushing this project forward. We also thank the authors who have contributed their excellent original articles to this issue, the referees whose comments have helped make the issue an accurate portrait of this rapidly moving field, and the entire NC-AFM community that continues to drive NC-AFM to new horizons.

  1. Bandwidth in bolometric interferometry

    Science.gov (United States)

    Charlassier, R.; Bunn, E. F.; Hamilton, J.-Ch.; Kaplan, J.; Malu, S.

    2010-05-01

    Context. Bolometric interferometry is a promising new technology with potential applications to the detection of B-mode polarization fluctuations of the cosmic microwave background (CMB). A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers to be competitive with imaging experiments. A crucial concern is that interferometers are assumed to be significantly affected by a spoiling effect known as bandwidth smearing. Aims: We investigate how the bandwidth modifies the work principle of a bolometric interferometer and affects its sensitivity to the CMB angular power spectra. Methods: We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. If the phase shifters produce shifts that are constant with respect to frequency, the instrument works like its monochromatic version (the modulation matrix is not modified), while if they vary (linearly or otherwise) with respect to frequency, one has to perform a special reconstruction scheme, which allows the visibilities to be reconstructed in frequency subbands. Using an angular power spectrum estimator that accounts for the bandwidth, we finally calculate the sensitivity of a broadband bolometric interferometer. A numerical simulation is performed that confirms the analytical results. Results: We conclude that (i) broadband bolometric interferometers allow broadband visibilities to be reconstructed regardless of the type of phase shifters used and (ii) for dedicated B-mode bolometric interferometers, the sensitivity loss caused by bandwidth smearing is quite acceptable, even for wideband instruments (a factor of 2 loss for a typical 20% bandwidth experiment).

  2. Protein high-force pulling simulations yield low-force results.

    Directory of Open Access Journals (Sweden)

    Seth Lichter

    Full Text Available All-atom explicit-solvent molecular dynamics simulations are used to pull with extremely large constant force (750-3000 pN on three small proteins. The introduction of a nondimensional timescale permits direct comparison of unfolding across all forces. A crossover force of approximately 1100 pN divides unfolding dynamics into two regimes. At higher forces, residues sequentially unfold from the pulling end while maintaining the remainder of the protein force-free. Measurements of hydrodynamic viscous stresses are made easy by the high speeds of unfolding. Using an exact low-Reynolds-number scaling, these measurements can be extrapolated to provide, for the first time, an estimate of the hydrodynamic force on low-force unfolding. Below 1100 pN, but surprisingly still at extremely large applied force, intermediate states and cooperative unfoldings as seen at much lower forces are observed. The force-insensitive persistence of these structures indicates that decomposition into unfolded fragments requires a large fluctuation. This finding suggests how proteins are constructed to resist transient high force. The progression of [Formula: see text] helix and [Formula: see text] sheet unfolding is also found to be insensitive to force. The force-insensitivity of key aspects of unfolding opens the possibility that numerical simulations can be accelerated by high applied force while still maintaining critical features of unfolding.

  3. Bandwidth in bolometric interferometry

    CERN Document Server

    Charlassier, R; Hamilton, J -Ch; Kaplan, J; Malu, S

    2009-01-01

    Bolometric Interferometry is a technology currently under development that will be first dedicated to the detection of B-mode polarization fluctuations in the Cosmic Microwave Background. A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers in order to be competitive with imaging experiments. A crucial concern is that interferometers are presumed to be importantly affected by a spoiling effect known as bandwidth smearing. In this paper, we investigate how the bandwidth modifies the work principle of a bolometric interferometer and how it affects its sensitivity to the CMB angular power spectra. We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. Using an angular power spectrum estimator ...

  4. Optical conductivity measurements of GaTa4Se8 under high pressure: evidence of a bandwidth-controlled insulator-to-metal Mott transition.

    Science.gov (United States)

    Ta Phuoc, V; Vaju, C; Corraze, B; Sopracase, R; Perucchi, A; Marini, C; Postorino, P; Chligui, M; Lupi, S; Janod, E; Cario, L

    2013-01-18

    The optical properties of a GaTa(4)Se(8) single crystal are investigated under high pressure. At ambient pressure, the optical conductivity exhibits a charge gap of ≈0.12 eV and a broad midinfrared band at ≈0.55 eV. As pressure is increased, the low energy spectral weight is strongly enhanced and the optical gap is rapidly filled, pointing to an insulator to metal transition around 6 GPa. The overall evolution of the optical conductivity demonstrates that GaTa(4)Se(8) is a Mott insulator which undergoes a bandwidth-controlled Mott metal-insulator transition under pressure, in remarkably good agreement with theory. With the use of our optical data and ab initio band structure calculations, our results were successfully compared to the (U/D, T/D) phase diagram predicted by dynamical mean field theory for strongly correlated systems.

  5. Bandwidth Trading as Incentive

    Science.gov (United States)

    Eger, Kolja; Killat, Ulrich

    In P2P networks with multi-source download the file of interest is fragmented into pieces and peers exchange pieces with each other although they did not finish the download of the complete file. Peers can adopt different strategies to trade upload for download bandwidth. These trading schemes should give peers an incentive to contribute bandwidth to the P2P network. This chapter studies different trading schemes analytically and by simulations. A mathematical framework for bandwidth trading is introduced and two distributed algorithms, which are denoted as Resource Pricing and Reciprocal Rate Control, are derived. The algorithms are compared to the tit-for-tat principle in BitTorrent. Nash Equilibria and results from simulations of static and dynamic networks are presented. Additionally, we discuss how trading schemes can be combined with a piece selection algorithm to increase the availability of a full copy of the file. The chapter closes with an extension of the mathematical model which takes also the underlying IP network into account. This results in a TCP variant optimised for P2P content distribution.

  6. Two-photon-excited fluorescence (TPEF) and fluorescence lifetime imaging (FLIM) with sub-nanosecond pulses and a high analog bandwidth signal detection

    Science.gov (United States)

    Eibl, Matthias; Karpf, Sebastian; Hakert, Hubertus; Weng, Daniel; Huber, Robert

    2017-02-01

    Two-photon excited fluorescence (TPEF) microscopy and fluorescence lifetime imaging (FLIM) are powerful imaging techniques in bio-molecular science. The need for elaborate light sources for TPEF and speed limitations for FLIM, however, hinder an even wider application. We present a way to overcome this limitations by combining a robust and inexpensive fiber laser for nonlinear excitation with a fast analog digitization method for rapid FLIM imaging. The applied sub nanosecond pulsed laser source is synchronized to a high analog bandwidth signal detection for single shot TPEF- and single shot FLIM imaging. The actively modulated pulses at 1064nm from the fiber laser are adjustable from 50ps to 5ns with kW of peak power. At a typically applied pulse lengths and repetition rates, the duty cycle is comparable to typically used femtosecond pulses and thus the peak power is also comparable at same cw-power. Hence, both types of excitation should yield the same number of fluorescence photons per time on average when used for TPEF imaging. However, in the 100ps configuration, a thousand times more fluorescence photons are generated per pulse. In this paper, we now show that the higher number of fluorescence photons per pulse combined with a high analog bandwidth detection makes it possible to not only use a single pulse per pixel for TPEF imaging but also to resolve the exponential time decay for FLIM. To evaluate the performance of our system, we acquired FLIM images of a Convallaria sample with pixel rates of 1 MHz where the lifetime information is directly measured with a fast real time digitizer. With the presented results, we show that longer pulses in the many-10ps to nanosecond regime can be readily applied for TPEF imaging and enable new imaging modalities like single pulse FLIM.

  7. Polybinary modulation for bandwidth limited optical links

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Jurado-Navas, Antonio

    2015-01-01

    Optical links using traditional modulation formats are reaching a plateau in terms of capacity, mainly due to bandwidth limitations in the devices employed at the transmitter and receivers. Advanced modulation formats, which boost the spectral efficiency, provide a smooth migration path towards...... the recent results on poly binary modulation, comprising both binary and multilevel signals as seed signals. The results will show how poly binary modulation effectively reduces the bandwidth requirements on optical links while providing high spectral efficiency....

  8. High-Multipolar Effects on Dispersive Forces

    CERN Document Server

    Noguez, C; Esquivel-Sirvent, R; Villarreal, C; Noguez, Cecilia; Roman-Velazquez, Carlos E.

    2003-01-01

    We show that the dispersive force between a spherical nanoparticle (with a radius $\\le$ 100 nm) and a substrate is enhanced by several orders of magnitude when the sphere is near to the substrate. We calculate exactly the dispersive force in the non-retarded limit by incorporating the contributions to the interaction from of all the multipolar electromagnetic modes. We show that as the sphere approaches the substrate, the fluctuations of the electromagnetic field, induced by the vacuum and the presence of the substrate, the dispersive force is enhanced by orders of magnitude. We discuss this effect as a function of the size of the sphere.

  9. Spectrophotometer spectral bandwidth calibration with absorption bands crystal standard.

    Science.gov (United States)

    Soares, O D; Costa, J L

    1999-04-01

    A procedure for calibration of a spectral bandwidth standard for high-resolution spectrophotometers is described. Symmetrical absorption bands for a crystal standard are adopted. The method relies on spectral band shape fitting followed by a convolution with the slit function of the spectrophotometer. A reference spectrophotometer is used to calibrate the spectral bandwidth standard. Bandwidth calibration curves for a minimum spectral transmission factor relative to the spectral bandwidth of the reference spectrophotometer are derived for the absorption bands at the wavelength of the band absorption maximum. The family of these calibration curves characterizes the spectral bandwidth standard. We calibrate the spectral bandwidth of a spectrophotometer with respect to the reference spectrophotometer by determining the spectral transmission factor minimum at every calibrated absorption band of the bandwidth standard for the nominal instrument values of the spectral bandwidth. With reference to the standard spectral bandwidth calibration curves, the relation of the spectral bandwidth to the reference spectrophotometer is determined. We determine the discrepancy in the spectrophotometers' spectral bandwidths by averaging the spectral bandwidth discrepancies relative to the standard calibrated values found at the absorption bands considered. A weighted average of the uncertainties is taken.

  10. Topology optimization of photonic crystal structures: a high-bandwidth low-loss T-junction waveguide

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Sigmund, Ole

    2005-01-01

    A T junction in a photonic crystal waveguide is designed with the topology-optimization method. The gradientbased optimization tool is used to modify the material distribution in the junction area so that the power transmission in the output ports is maximized. To obtain high transmission...

  11. High-Bandwidth AFM-Based Rheology Reveals that Cartilage is Most Sensitive to High Loading Rates at Early Stages of Impairment

    Science.gov (United States)

    Nia, Hadi Tavakoli; Bozchalooi, Iman S.; Li, Yang; Han, Lin; Hung, Han-Hwa; Frank, Eliot; Youcef-Toumi, Kamal; Ortiz, Christine; Grodzinsky, Alan

    2013-01-01

    Utilizing a newly developed atomic-force-microscopy-based wide-frequency rheology system, we measured the dynamic nanomechanical behavior of normal and glycosaminoglycan (GAG)-depleted cartilage, the latter representing matrix degradation that occurs at the earliest stages of osteoarthritis. We observed unique variations in the frequency-dependent stiffness and hydraulic permeability of cartilage in the 1 Hz-to-10 kHz range, a frequency range that is relevant to joint motions from normal ambulation to high-frequency impact loading. Measurement in this frequency range is well beyond the capabilities of typical commercial atomic force microscopes. We showed that the dynamic modulus of cartilage undergoes a dramatic alteration after GAG loss, even with the collagen network still intact: whereas the magnitude of the dynamic modulus decreased two- to threefold at higher frequencies, the peak frequency of the phase angle of the modulus (representing fluid-solid frictional dissipation) increased 15-fold from 55 Hz in normal cartilage to 800 Hz after GAG depletion. These results, based on a fibril-reinforced poroelastic finite-element model, demonstrated that GAG loss caused a dramatic increase in cartilage hydraulic permeability (up to 25-fold), suggesting that early osteoarthritic cartilage is more vulnerable to higher loading rates than to the conventionally studied “loading magnitude”. Thus, over the wide frequency range of joint motion during daily activities, hydraulic permeability appears the most sensitive marker of early tissue degradation. PMID:23561529

  12. New linear piezomotors for high-force precise positioning applications

    Science.gov (United States)

    Le Letty, Ronan; Claeyssen, Frank; Barillot, Francois; Six, Marc F.; Bouchilloux, Philippe

    1998-07-01

    Piezomotors are an increasingly competitive alternative to electromagnetic stepper motors, especially in applications where large bandwidths and/or precise positioning control are desired. Piezomotors use a combination of electromechanical and frictional forces and, compared to conventional electromagnetic motors, have the advantages that no power supply is required to maintain the motor in position and no lubrication is necessary in the device. The operating principle of these motors relies on the use of an ultrasonic vibration, which is created via the piezoelectric effect (at resonance in most cases), in order to generate vibration forces at the `stator/rotor' contact interface. A mechanical preload is also applied at this contact interface and is responsible for the motor's holding force at rest. To meet the specifications of an aerospace application, we developed a new design of Linear PiezoMotors (LPMs). The first prototype we built shows very promising results, and makes the LPM a serious candidate to replace conventional stepper motors. The LPM features the following characteristics: a standing force of 100 N, a blocked force of 37 N, a maximum actuation speed of 23 mm/s, a maximum run of 10 mm, a mass of 500 g, an electrical power of 2.2 W, and a position accuracy superior to 1 micrometers . To our knowledge, the driving force delivered by the LPM has never before been achieved in resonant devices. This paper describes the physical operating principles of the LPM, as well as the modeling tools and experimental techniques we used for its development. Several implementation schemes are also presented and show the wide range of possible applications offered by the linear piezomotor.

  13. Health care using high-bandwidth communication to overcome distance and time barriers for the Department of Defense

    Science.gov (United States)

    Mun, Seong K.; Freedman, Matthew T.; Gelish, Anthony; de Treville, Robert E.; Sheehy, Monet R.; Hansen, Mark; Hill, Mac; Zacharia, Elisabeth; Sullivan, Michael J.; Sebera, C. Wayne

    1993-01-01

    Image management and communications (IMAC) network, also known as picture archiving and communication system (PACS) consists of (1) digital image acquisition, (2) image review station (3) image storage device(s), image reading workstation, and (4) communication capability. When these subsystems are integrated over a high speed communication technology, possibilities are numerous in improving the timeliness and quality of diagnostic services within a hospital or at remote clinical sites. Teleradiology system uses basically the same hardware configuration together with a long distance communication capability. Functional characteristics of components are highlighted. Many medical imaging systems are already in digital form. These digital images constitute approximately 30% of the total volume of images produced in a radiology department. The remaining 70% of images include conventional x-ray films of the chest, skeleton, abdomen, and GI tract. Unless one develops a method of handling these conventional film images, global improvement in productivity in image management and radiology service throughout a hospital cannot be achieved. Currently, there are two method of producing digital information representing these conventional analog images for IMAC: film digitizers that scan the conventional films, and computed radiography (CR) that captures x-ray images using storage phosphor plate that is subsequently scanned by a laser beam.

  14. Live Educational Outreach for Ocean Exploration: High-Bandwidth Ship-to-Shore Broadcasts Using Internet2

    Science.gov (United States)

    Coleman, D. F.; Ballard, R. D.

    2005-12-01

    During the past 3 field seasons, our group at the University of Rhode Island Graduate School of Oceanography, in partnership with the Institute for Exploration and a number of educational institutions, has conducted a series of ocean exploration expeditions with a significant focus on educational outreach through "telepresence" - utilizing live transmissions of video, audio, and data streams across the Internet and Internet2. Our educational partners include Immersion Presents, Boys and Girls Clubs of America, the Jason Foundation for Education, and the National Geographic Society, all who provided partial funding for the expeditions. The primary funding agency each year was NOAA's Office of Ocean Exploration and our outreach efforts were conducted in collaboration with them. During each expedition, remotely operated vehicle (ROV) systems were employed to examine interesting geological and archaeological sites on the seafloor. These expeditions include the investigation of ancient shipwrecks in the Black Sea in 2003, a survey of the Titanic shipwreck site in 2004, and a detailed sampling and mapping effort at the Lost City Hydrothermal Field in 2005. High-definition video cameras on the ROVs collected the footage that was then digitally encoded, IP-encapsulated, and streamed across a satellite link to a shore-based hub, where the streams were redistributed. During each expedition, live half-hour-long educational broadcasts were produced 4 times per day for 10 days. These shows were distributed using satellite and internet technologies to a variety of venues, including museums, aquariums, science centers, public schools, and universities. In addition to the live broadcasts, educational products were developed to enhance the learning experience. These include activity modules and curriculum-based material for teachers and informal educators. Each educational partner also maintained a web site that followed the expedition and provided additional background information

  15. Bandwidth Estimation For Mobile Ad hoc Network (MANET

    Directory of Open Access Journals (Sweden)

    Rabia Ali

    2011-09-01

    Full Text Available In this paper we presents bandwidth estimation scheme for MANET, which uses some components of the two methods for the bandwidth estimation: 'Hello Bandwidth Estimation 'Listen Bandwidth Estimation. This paper also gives the advantages of the proposed method. The proposed method is based on the comparison of these two methods. Bandwidth estimation is an important issue in the Mobile Ad-hoc Network (MANET because bandwidth estimation in MANET is difficult, because each host has imprecise knowledge of the network status and links change dynamically. Therefore, an effective bandwidth estimation scheme for MANET is highly desirable. Ad hoc networks present unique advanced challenges, including the design of protocols for mobility management, effective routing, data transport, security, power management, and quality-of-service (QoS provisioning. Once these problems are solved, the practical use of MANETs will be realizable.

  16. Imaging stability in force-feedback high-speed atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byung I., E-mail: ByungKim@boisestate.edu [Department of Physics, Boise State University, 1910 University Drive Boise, ID 83725-1570, United States of America (United States); Boehm, Ryan D. [Department of Physics, Boise State University, 1910 University Drive Boise, ID 83725-1570, United States of America (United States)

    2013-02-15

    We studied the stability of force-feedback high-speed atomic force microscopy (HSAFM) by imaging soft, hard, and biological sample surfaces at various applied forces. The HSAFM images showed sudden topographic variations of streaky fringes with a negative applied force when collected on a soft hydrocarbon film grown on a grating sample, whereas they showed stable topographic features with positive applied forces. The instability of HSAFM images with the negative applied force was explained by the transition between contact and noncontact regimes in the force–distance curve. When the grating surface was cleaned, and thus hydrophilic by removing the hydrocarbon film, enhanced imaging stability was observed at both positive and negative applied forces. The higher adhesive interaction between the tip and the surface explains the improved imaging stability. The effects of imaging rate on the imaging stability were tested on an even softer adhesive Escherichia coli biofilm deposited onto the grating structure. The biofilm and planktonic cell structures in HSAFM images were reproducible within the force deviation less than ∼0.5 nN at the imaging rate up to 0.2 s per frame, suggesting that the force-feedback HSAFM was stable for various imaging speeds in imaging softer adhesive biological samples. - Highlights: ► We investigated the imaging stability of force-feedback HSAFM. ► Stable–unstable imaging transitions rely on applied force and sample hydrophilicity. ► The stable–unstable transitions are found to be independent of imaging rate.

  17. Ultrahigh bandwidth signal processing

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo

    2016-01-01

    Optical time lenses have proven to be very versatile for advanced optical signal processing. Based on a controlled interplay between dispersion and phase-modulation by e.g. four-wave mixing, the processing is phase-preserving, an hence useful for all types of data signals including coherent multi......-level modulation founats. This has enabled processing of phase-modulated spectrally efficient data signals, such as orthogonal frequency division multiplexed (OFDM) signa In that case, a spectral telescope system was used, using two time lenses with different focal lengths (chirp rates), yielding a spectral...... regeneratio These operations require a broad bandwidth nonlinear platform, and novel photonic integrated nonlinear platform like aluminum gallium arsenide nano-waveguides used for 1.28 Tbaud optical signal processing will be described....

  18. Bandwidth enhancement and time-delay signature suppression of chaotic signal from an optical feedback semiconductor laser by using cross phase modulation in a highly nonlinear fiber loop mirror

    Science.gov (United States)

    Wang, Liang-Yan; Zhong, Zhu-Qiong; Wu, Zheng-Mao; Lu, Dong; Chen, Xi; Chen, Jun; Xia, Guang-Qiong

    2016-11-01

    Based on a nonlinear fiber loop mirror (NOLM) composed of a fiber coupler (FC) and a highly nonlinear fiber (HNLF), a scheme is proposed to simultaneously realize the bandwidth enhancement and the time-delay signature (TDS) suppression of a chaotic signal generated from an external cavity optical feedback semiconductor laser. The simulation results show that, after passing through the NOLM, the bandwidth of chaotic signal can be efficiently enhanced and the TDS can be well suppressed under suitable operation parameters. Furthermore, the influences of the power-splitting ratio of the FC, the averaged power of the chaotic signal entering into the FC and the length of the HNLF on the chaotic bandwidth and TDS are analyzed, and the optimized parameters are determined.

  19. Ultrawide bandwidth 1.55-um lasers

    Science.gov (United States)

    Morton, Paul A.; Tanbun-Ek, Tawee; Logan, Ralph A.; Ackerman, David A.; Shtengel, Gleb E.; Yadvish, R. D.; Sergent, A. M.; Sciortino, Paul F., Jr.

    1996-04-01

    This paper describes the essential elements for creating a practical wide bandwidth directly modulated laser source. This includes considerations of the intrinsic limitations of the laser structure, due to the resonant frequency and damping of the laser output, together with carrier transport issues to allow carriers in the device active region to be efficiently modulated at high speeds. the use of a P-doped compressively strained multiple-quantum well active region to provide high intrinsic speed and remove transport limitations is described, together with record setting results of 25 GHz modulation bandwidth for a 1.55 micrometer Fabry-Perot laser and 26 GHz bandwidth for a 1.55 micrometer DFB laser. The challenges of providing high bandwidth electrical connections to the laser on a suitable submount, together with fiber attachment and microwave packaging, are discussed. Results of fully packaged 1.55 micrometer DFB lasers with 25 Ghz modulation bandwidth are shown. Digital modulation of the packaged 1.55 micrometer DFB including impedance matching is described, and the transient wavelength chirp is presented. This low chirp is reduced further using an optical filter, to provide a 10 GBit/s source with chirp similar to that of an external electroabsorption modulator.

  20. Bandwidth and Noise in Spatiotemporally Modulated Mueller Matrix Polarimeters

    Science.gov (United States)

    Vaughn, Israel Jacob

    Polarimetric systems design has seen recent utilization of linear systems theory for system descriptions. Although noise optimal systems have been shown, bandwidth performance has not been addressed in depth generally and is particularly lacking for Mueller matrix (active) polarimetric systems. Bandwidth must be considered in a systematic way for remote sensing polarimetric systems design. The systematic approach facilitates both understanding of fundamental constraints and design of higher bandwidth polarimetric systems. Fundamental bandwidth constraints result in production of polarimetric "artifacts" due to channel crosstalk upon Mueller matrix reconstruction. This dissertation analyzes bandwidth trade-offs in spatio-temporal channeled Mueller matrix polarimetric systems. Bandwidth is directly related to the geometric positioning of channels in the Fourier (channel) space, however channel positioning for polarimetric systems is constrained both physically and by design parameters like domain separability. We present the physical channel constraints and the constraints imposed when the carriers are separable between space and time. Polarimetric systems are also constrained by noise performance, and there is a trade-off between noise performance and bandwidth. I develop cost functions which account for the trade-off between noise and bandwidth for spatio-temporal polarimetric systems. The cost functions allow a systems designer to jointly optimize systems with good bandwidth and noise performance. Optimization is implemented for a candidate spatio-temporal system design, and high temporal bandwidth systems resulting from the optimization are presented. Systematic errors which impact the bandwidth performance and mitigation strategies for these systematic errors are also presented. Finally, a portable imaging Mueller matrix system is built and analyzed based on the theoretical bandwidth analysis and system bandwidth optimization. Temporal bandwidth performance is

  1. Ultrahigh bandwidth signal processing

    Science.gov (United States)

    Oxenløwe, Leif Katsuo

    2016-04-01

    Optical time lenses have proven to be very versatile for advanced optical signal processing. Based on a controlled interplay between dispersion and phase-modulation by e.g. four-wave mixing, the processing is phase-preserving, and hence useful for all types of data signals including coherent multi-level modulation formats. This has enabled processing of phase-modulated spectrally efficient data signals, such as orthogonal frequency division multiplexed (OFDM) signals. In that case, a spectral telescope system was used, using two time lenses with different focal lengths (chirp rates), yielding a spectral magnification of the OFDM signal. Utilising such telescopic arrangements, it has become possible to perform a number of interesting functionalities, which will be described in the presentation. This includes conversion from OFDM to Nyquist WDM, compression of WDM channels to a single Nyquist channel and WDM regeneration. These operations require a broad bandwidth nonlinear platform, and novel photonic integrated nonlinear platforms like aluminum gallium arsenide nano-waveguides used for 1.28 Tbaud optical signal processing will be described.

  2. Theoretical Calculation of MMF's Bandwidth

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-fu; JIANG De-sheng; YU Hai-hu

    2004-01-01

    The difference between over-filled launch bandwidth (OFL BW) and restricted mode launch bandwidth (RML BW) is described. A theoretical model is founded to calculate the OFL BW of grade index multimode fiber (GI-MMF),and the result is useful to guide the modification of the manufacturing method.

  3. Estimating Bottleneck Bandwidth using TCP

    Science.gov (United States)

    Allman, Mark

    1998-01-01

    Various issues associated with estimating bottleneck bandwidth using TCP are presented in viewgraph form. Specific topics include: 1) Why TCP is wanted to estimate the bottleneck bandwidth; 2) Setting ssthresh to an appropriate value to reduce loss; 3) Possible packet-pair solutions; and 4) Preliminary results: ACTS and the Internet.

  4. Bandwidth of Gaussian weighted Chirp

    DEFF Research Database (Denmark)

    Wilhjelm, Jens E.

    1993-01-01

    Four major time duration and bandwidth expressions are calculated for a linearly frequency modulated sinusoid with Gaussian shaped envelope. This includes a Gaussian tone pulse. The bandwidth is found to be a nonlinear function of nominal time duration and nominal frequency excursion of the chirp...

  5. Improved-Bandwidth Transimpedance Amplifier

    Science.gov (United States)

    Chapsky, Jacob

    2009-01-01

    The widest available operational amplifier, with the best voltage and current noise characteristics, is considered for transimpedance amplifier (TIA) applications where wide bandwidth is required to handle fast rising input signals (as for time-of-flight measurement cases). The added amplifier inside the TIA feedback loop can be configured to have slightly lower voltage gain than the bandwidth reduction factor.

  6. Compact antenna arrays with wide bandwidth and low sidelobe levels

    Science.gov (United States)

    Strassner, II, Bernd H.

    2014-09-09

    Highly efficient, low cost, easily manufactured SAR antenna arrays with lightweight low profiles, large instantaneous bandwidths and low SLL are disclosed. The array topology provides all necessary circuitry within the available antenna aperture space and between the layers of material that comprise the aperture. Bandwidths of 15.2 GHz to 18.2 GHz, with 30 dB SLLs azimuthally and elevationally, and radiation efficiencies above 40% may be achieved. Operation over much larger bandwidths is possible as well.

  7. VisIO: enabling interactive visualization of ultra-scale, time-series data via high-bandwidth distributed I/O systems

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Christopher J [Los Alamos National Laboratory; Ahrens, James P [Los Alamos National Laboratory; Wang, Jun [UCF

    2010-10-15

    Petascale simulations compute at resolutions ranging into billions of cells and write terabytes of data for visualization and analysis. Interactive visuaUzation of this time series is a desired step before starting a new run. The I/O subsystem and associated network often are a significant impediment to interactive visualization of time-varying data; as they are not configured or provisioned to provide necessary I/O read rates. In this paper, we propose a new I/O library for visualization applications: VisIO. Visualization applications commonly use N-to-N reads within their parallel enabled readers which provides an incentive for a shared-nothing approach to I/O, similar to other data-intensive approaches such as Hadoop. However, unlike other data-intensive applications, visualization requires: (1) interactive performance for large data volumes, (2) compatibility with MPI and POSIX file system semantics for compatibility with existing infrastructure, and (3) use of existing file formats and their stipulated data partitioning rules. VisIO, provides a mechanism for using a non-POSIX distributed file system to provide linear scaling of 110 bandwidth. In addition, we introduce a novel scheduling algorithm that helps to co-locate visualization processes on nodes with the requested data. Testing using VisIO integrated into Para View was conducted using the Hadoop Distributed File System (HDFS) on TACC's Longhorn cluster. A representative dataset, VPIC, across 128 nodes showed a 64.4% read performance improvement compared to the provided Lustre installation. Also tested, was a dataset representing a global ocean salinity simulation that showed a 51.4% improvement in read performance over Lustre when using our VisIO system. VisIO, provides powerful high-performance I/O services to visualization applications, allowing for interactive performance with ultra-scale, time-series data.

  8. Optimal resource allocation in random networks with transportation bandwidths

    Science.gov (United States)

    Yeung, C. H.; Wong, K. Y. Michael

    2009-03-01

    We apply statistical physics to study the task of resource allocation in random sparse networks with limited bandwidths for the transportation of resources along the links. Recursive relations from the Bethe approximation are converted into useful algorithms. Bottlenecks emerge when the bandwidths are small, causing an increase in the fraction of idle links. For a given total bandwidth per node, the efficiency of allocation increases with the network connectivity. In the high connectivity limit, we find a phase transition at a critical bandwidth, above which clusters of balanced nodes appear, characterized by a profile of homogenized resource allocation similar to the Maxwell construction.

  9. Task force for integral test of High Energy nuclear data

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-11-01

    According to completion of the JENDL-High Energy file for neutron nuclear cross sections up to 50 MeV, a task force for integral test of high energy nuclear data was organized to discuss a guide line for integral test activities. A status of existing differential and integral experiments and how to perform such a test were discussed in the task force. Here the purpose and outline of the task force is explained with some future problems raised in discussion among the task member. (author)

  10. Upgrade trigger: Bandwidth strategy proposal

    CERN Document Server

    Fitzpatrick, Conor; Meloni, Simone; Boettcher, Thomas Julian; Whitehead, Mark Peter; Dziurda, Agnieszka; Vesterinen, Mika Anton

    2017-01-01

    This document describes a selection strategy for the upgrade trigger using charm signals as a benchmark. The Upgrade trigger uses a 'Run 2-like' sequence consisting of a first and second stage, in between which the calibration and alignment is performed. The first stage, HLT1, uses an inclusive strategy to select beauty and charm decays, while the second stage uses offline-quality exclusive selections. A novel genetic algorithm-based bandwidth division is performed at the second stage to distribute the output bandwidth among different physics channels, maximising the efficiency for useful physics events. The performance is then studied as a function of the available output bandwidth.

  11. Simulation and Analysis of Router Buffer Requirements in High Bandwidth-Delay Networks%高带宽延迟网络中路由器缓存需求的仿真分析

    Institute of Scientific and Technical Information of China (English)

    王建新; 李春泉; 黄家玮

    2009-01-01

    In order to meet the requirement for router buffer size in high bandwidth-delay networks, five typical buffer-sizing methods based on the TCP model are analyzed via the NS2 simulation, and the effects of various high-speed TCP protocols and active queue management (AQM) mechanisms on the buffer-sizing methods in high bandwidth-delay networks are discussed in detail. Simulated results show that: (1) the buffer-sizing methods based on different assumptions adapt to different network environments; (2) the validity of the existing cache mechanisms depends on the ratio of the bandwidth-delay product to the flow number; and (3) when high-speed TCP protocols and AQM mechanisms are used in high bandwidth-delay networks, the buffer size is greatly reduced.%文中针对当今高带宽延迟网络下路由器缓存大小的需求问题,通过NS2仿真实验,对基于TCP协议模型的5种典型的缓存设置方法展开研究,着重分析了在高带宽延迟网络下各种高速TCP协议和主动队列管理(AQM)机制对各种缓存设置方法的影响.仿真实验表明:基于不同假设前提的缓存设置方法适应于不同的网络负载环境;缓存机制的选择取决于网络带宽延迟乘积与流数的比值;在高带宽延迟网络下,当采用高速TCP协议和AQM机制时,缓存需求可以大大减小.

  12. High-throughput screening for modulators of cellular contractile force

    CERN Document Server

    Park, Chan Young; Tambe, Dhananjay; Chen, Bohao; Lavoie, Tera; Dowell, Maria; Simeonov, Anton; Maloney, David J; Marinkovic, Aleksandar; Tschumperlin, Daniel J; Burger, Stephanie; Frykenberg, Matthew; Butler, James P; Stamer, W Daniel; Johnson, Mark; Solway, Julian; Fredberg, Jeffrey J; Krishnan, Ramaswamy

    2014-01-01

    When cellular contractile forces are central to pathophysiology, these forces comprise a logical target of therapy. Nevertheless, existing high-throughput screens are limited to upstream signaling intermediates with poorly defined relationship to such a physiological endpoint. Using cellular force as the target, here we screened libraries to identify novel drug candidates in the case of human airway smooth muscle cells in the context of asthma, and also in the case of Schlemm's canal endothelial cells in the context of glaucoma. This approach identified several drug candidates for both asthma and glaucoma. We attained rates of 1000 compounds per screening day, thus establishing a force-based cellular platform for high-throughput drug discovery.

  13. The FORCE: A highly portable parallel programming language

    Science.gov (United States)

    Jordan, Harry F.; Benten, Muhammad S.; Alaghband, Gita; Jakob, Ruediger

    1989-01-01

    Here, it is explained why the FORCE parallel programming language is easily portable among six different shared-memory microprocessors, and how a two-level macro preprocessor makes it possible to hide low level machine dependencies and to build machine-independent high level constructs on top of them. These FORCE constructs make it possible to write portable parallel programs largely independent of the number of processes and the specific shared memory multiprocessor executing them.

  14. The FORCE - A highly portable parallel programming language

    Science.gov (United States)

    Jordan, Harry F.; Benten, Muhammad S.; Alaghband, Gita; Jakob, Ruediger

    1989-01-01

    This paper explains why the FORCE parallel programming language is easily portable among six different shared-memory multiprocessors, and how a two-level macro preprocessor makes it possible to hide low-level machine dependencies and to build machine-independent high-level constructs on top of them. These FORCE constructs make it possible to write portable parallel programs largely independent of the number of processes and the specific shared-memory multiprocessor executing them.

  15. INTERPARTICLE FORCES IN HIGH TEMPERATURE FLUIDIZATION OF GELDART A PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Heping Cui; Jamal Chaouki

    2004-01-01

    Previous reports and current studies show that fluidization of some Geldart A particles is enhanced by increasing bed temperature. Both the averaged local particle concentration and the particle concentration in the dense phase decrease with increasing bed temperature, at constant superficial gas velocities. However, conventional models fail to predict these changes, because the role of interparticle forces is usually neglected at different bed temperatures.Here, the interparticle forces are analyzed to explore the mechanism of gas-solid fluidization at high temperatures. Indeed, as the temperature increases, the interparticle attractive forces decrease while the interparticle repulsive forces increase. Consequently, fluidization behaviors of some Geldart A particles seem to increasingly shift from typical Geldart A towards B with increasing temperature.

  16. Multi-actuation and PI control: A simple recipe for high-speed and large-range atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Soltani Bozchalooi, I., E-mail: isoltani@mit.edu; Youcef-Toumi, K.

    2014-11-15

    High speed atomic force microscopy enables observation of dynamic nano-scale processes. However, maintaining a minimal interaction force between the sample and the probe is challenging at high speed specially when using conventional piezo-tubes. While rigid AFM scanners are operational at high speeds with the drawback of reduced tracking range, multi-actuation schemes have shown potential for high-speed and large-range imaging. Here we present a method to seamlessly incorporate additional actuators into conventional AFMs. The equivalent behavior of the resulting multi-actuated setup resembles that of a single high-speed and large-range actuator with maximally flat frequency response. To achieve this, the dynamics of the individual actuators and their couplings are treated through a simple control scheme. Upon the implementation of the proposed technique, commonly used PI controllers are able to meet the requirements of high-speed imaging. This forms an ideal platform for retroactive enhancement of existing AFMs with minimal cost and without compromise on the tracking range. A conventional AFM with tube scanner is retroactively enhanced through the proposed method and shows an order of magnitude improvement in closed loop bandwidth performance while maintaining large range. The effectiveness of the method is demonstrated on various types of samples imaged in contact and tapping modes, in air and in liquid. - Highlights: • We present a novel method to incorporate extra actuators into conventional AFMs. • A maximally flat frequency response is achieved for the out of plane piezo-motion. • Commonly used PI or PID control is enabled to handle high speed AFM imaging. • An order of magnitude improvement in closed loop bandwidth performance is obtained. • High speed imaging is achieved on a large range piezo-tube.

  17. High-Bandwidth, High-Efficiency Envelope Tracking Power Supply for 40W RF Power Amplifier Using Paralleled Bandpass Current Sources

    DEFF Research Database (Denmark)

    Høyerby, Mikkel Christian Wendelboe; Andersen, Michael Andreas E.

    2005-01-01

    This paper presents a high-performance power conversion scheme for power supply applications that require very high output voltage slew rates (dV/dt). The concept is to parallel 2 switching bandpass current sources, each optimized for its passband frequency space and the expected load current....... The principle is demonstrated with a power supply, designed for supplying a 40 W linear RF power amplifier for efficient amplification of a 16-QAM modulated data stream...

  18. 高灵敏度微小卫星可变带宽接收机设计%Design of variable loop bandwidth high sensitivity micro-satellite receiver

    Institute of Scientific and Technical Information of China (English)

    张朝杰; 金小军; 杨伟君; 金仲和

    2011-01-01

    针对微小卫星发射功率低、天线增益小的特点对星载测控应答机提出的高接收灵敏度及高动态范围要求,研究卫星接收机的实现方法.提出一种基于正交欠采样技术及全数字载波恢复环的可变带宽卫星接收机结构.在全数字载波恢复环的实现中,通过相干自动增益控制(AGC)来控制环路带宽,使得在高信噪比下的环路带宽增大,从而获得更佳的跟踪性能;在低信噪比下,降低环路带宽使得接收机有更高的接收灵敏度.经实验测试可知,在250Hz环路带宽下,接收灵敏度为-144 dBm,动态范围达到80 dB以上.%The characteristic of low transmit power and antenna gain in micro-satellite requires high receiver sensitivity and high dynamic range for board transponders. A variable loop bandwidth receiver architecture based on all digital carrier recovery loop was presented using I/Q sub-sampling technique. A coherent automatic gain control (AGC) was used in order to control the loop bandwidth. The loop bandwidth was expanded to achieve better tracking performance at high signal to noise ratio; the loop bandwidth was decreased to realize high receiver sensitivity at low signal to noise ratio. -144 dBm receiver sensitivity was achieved and the dynamic range was better than 80 dB under the condition of 250 Hz loop bandwidth.

  19. A digital calibration technique for an ultra high-speed wide-bandwidth folding and interpolating analog-to-digital converter in 0.18-μm CMOS technology*

    Institute of Scientific and Technical Information of China (English)

    Yu Jinshan; Zhang Ruitao; Zhang Zhengping; Wang Yonglu; Zhu Can; Zhang Lei; Yu Zhou; Han Yong

    2011-01-01

    A digital calibration technique for an ultra high-speed folding and interpolating analog-to-digital converter in 0.18-μm CMOS technology is presented. The similar digital calibration techniques are taken for high 3-bit flash converter and low 5-bit folding and interpolating converter, which are based on well-designed calibration reference, calibration DAC and comparators. The spice simulation and the measured results show the ADC produces 5.9 ENOB with calibration disabled and 7.2 ENOB with calibration enabled for high-frequency wide-bandwidth analog input.

  20. Black Holes, Bandwidths and Beethoven

    CERN Document Server

    Kempf, A

    2000-01-01

    It is usually believed that a function whose Fourier spectrum is bounded can vary at most as fast as its highest frequency component. This is in fact not the case, as Aharonov, Berry and others drastically demonstrated with explicit counter examples, so-called superoscillations. The claim is that even the recording of an entire Beethoven symphony can occur as part of a signal with 1Hz bandwidth. Superoscillations have been suggested to account e.g. for transplanckian frequencies of black hole radiation. Here, we give an exact proof for generic superoscillations. Namely, we show that for every fixed bandwidth there exist functions which pass through any finite number of arbitrarily prespecified points. Further, we show that the behavior of bandlimited functions can be reliably characterized through an uncertainty relation for the standard deviation of the signals' samples taken at the Nyquist rate. This uncertainty relation generalizes to time-varying bandwidths.

  1. Force

    CERN Document Server

    Graybill, George

    2007-01-01

    Forces are at work all around us. Discover what a force is, and different kinds of forces that work on contact and at a distance. We use simple language and vocabulary to make this invisible world easy for students to ""see"" and understand. Examine how forces ""add up"" to create the total force on an object, and reinforce concepts and extend learning with sample problems.

  2. Upgrade trigger: Bandwidth strategy proposal

    CERN Document Server

    Boettcher, Thomas Julian; Meloni, Simone; Whitehead, Mark Peter; Williams, Mark Richard James

    2017-01-01

    This document describes a proposed selection strategy for the upgrade trigger using charm signals as a benchmark. The Upgrade trigger uses a 'Run2-like' sequence consisting of a first and second stage, in between which the calibration and alignment is performed. The first stage, HLT1, uses an inclusive strategy to select beauty and charm, while the second stage uses offline-quality exclusive selections. A novel genetic algorithm-based bandwidth division is performed at the second stage to maximise the output of useful physics events, and a range of possible signal efficiencies are presented as a function of the available bandwidth.

  3. Mining Industry Energy Bandwidth Study

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2007-07-01

    The Industrial Technologies Program (ITP) relies on analytical studies to identify large energy reduction opportunities in energy-intensive industries and uses these results to guide its R&D portfolio. The energy bandwidth illustrates the total energy-saving opportunity that exists in the industry if the current processes are improved by implementing more energy-efficient practices and by using advanced technologies. This bandwidth analysis report was conducted to assist the ITP Mining R&D program in identifying energy-saving opportunities in coal, metals, and mineral mining. These opportunities were analyzed in key mining processes of blasting, dewatering, drilling, digging, ventilation, materials handling, crushing, grinding, and separations.

  4. High-speed Lissajous-scan atomic force microscopy: scan pattern planning and control design issues.

    Science.gov (United States)

    Bazaei, A; Yong, Yuen K; Moheimani, S O Reza

    2012-06-01

    Tracking of triangular or sawtooth waveforms is a major difficulty for achieving high-speed operation in many scanning applications such as scanning probe microscopy. Such non-smooth waveforms contain high order harmonics of the scan frequency that can excite mechanical resonant modes of the positioning system, limiting the scan range and bandwidth. Hence, fast raster scanning often leads to image distortion. This paper proposes analysis and design methodologies for a nonlinear and smooth closed curve, known as Lissajous pattern, which allows much faster operations compared to the ordinary scan patterns. A simple closed-form measure is formulated for the image resolution of the Lissajous pattern. This enables us to systematically determine the scan parameters. Using internal model controllers (IMC), this non-raster scan method is implemented on a commercial atomic force microscope driven by a low resonance frequency positioning stage. To reduce the tracking errors due to actuator nonlinearities, higher order harmonic oscillators are included in the IMC controllers. This results in significant improvement compared to the traditional IMC method. It is shown that the proposed IMC controller achieves much better tracking performances compared to integral controllers when the noise rejection performances is a concern.

  5. Acceleration of objects to high velocity by electromagnetic forces

    Energy Technology Data Exchange (ETDEWEB)

    Post, Richard F

    2017-02-28

    Two exemplary approaches to the acceleration of projectiles are provided. Both approaches can utilize concepts associated with the Inductrack maglev system. Either of them provides an effective means of accelerating multi-kilogram projectiles to velocities of several kilometers per second, using launchers of order 10 meters in length, thus enabling the acceleration of projectiles to high velocities by electromagnetic forces.

  6. Period Prevalence of Acute Neck Injury in US Air Force Pilots Exposed to High G Forces

    Science.gov (United States)

    1986-06-01

    unquantified clinical and epidemiological problem in exposed pilots. There has been a paucity of research in this area. This proposal is a beginning, with a...larg-e majority of pilots. Thus neck injury and its sequelae are unquantified clinical and epidemiological problems in pilots exposed to high G forces...Basal Impression 19. Cervical Ribs 20. Scoliosis , 21. Intraspongy Nuclear Hernitation 22. Significant Compression or Loss of Height of Any Vertebral

  7. High-Resolution Force Balance Analyses of Tidewater Glacier Dynamics

    Science.gov (United States)

    Enderlin, E. M.; Hamilton, G. S.; O'Neel, S.

    2015-12-01

    Changes in glacier velocity, thickness, and terminus position have been used to infer the dynamic response of tidewater glaciers to environmental perturbations, yet few analyses have attempted to quantify the associated variations in the glacier force balance. Where repeat high-resolution ice thickness and velocity estimates are available, force balance time series can be constructed to investigate the redistribution of driving and resistive forces associated with changes in terminus position. Comparative force balance analyses may, therefore, help us understand the variable dynamic response observed for glaciers in close proximity to each other. Here we construct force balance time series for Helheim Glacier, SE Greenland, and Columbia Glacier, SE Alaska, to investigate differences in dynamic sensitivity to terminus position change. The analysis relies on in situ and remotely sensed observations of ice thickness, velocity, and terminus position. Ice thickness time series are obtained from stereo satellite image-derived surface elevation and continuity-derived bed elevations that are constrained by airborne radar observations. Surface velocity time series are obtained from interferometric synthetic aperture radar (InSAR) observations. Approximately daily terminus positions are from a combination of satellite images and terrestrial time-lapse photographs. Helheim and Columbia glaciers are two of the best-studied Arctic tidewater glaciers with comprehensive high-resolution observational time series, yet we find that bed elevation uncertainties and poorly-constrained stress-coupling length estimates still hinder the analysis of spatial and temporal force balance variations. Here we use a new observationally-based method to estimate the stress-coupling length which successfully reduces noise in the derived force balance but preserves spatial variations that can be over-smoothed when estimating the stress-coupling length as a scalar function of the ice thickness

  8. All-optical bandwidth-tailorable radar

    CERN Document Server

    Zou, Weiwen; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2015-01-01

    Radar has been widely used in military, security, and rescue. Metamaterial cloak is employed in stealth targets to evade radar detection. Hence modern radar should be reconfigurable at multi-bands for detecting stealth targets, which might be realized based on microwave photonics. Here, we demonstrate an all-optical bandwidth-tailorable radar architecture. It is a coherent system utilizing one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates wideband linearly-chirped radar signal. The working bands can be flexibly tailored with desired bandwidth at user-preferred carrier frequency. After modulated onto the pre-chirped optical pulse, radar echoes are time-stretched and frequency-compressed by several times. The digitization becomes much easier without loss of detection ability. We believe that the demonstration can innovate the radar's architecture with ultra-high range resolution.

  9. High-resolution friction force microscopy under electrochemical control

    Science.gov (United States)

    Labuda, Aleksander; Paul, William; Pietrobon, Brendan; Lennox, R. Bruce; Grütter, Peter H.; Bennewitz, Roland

    2010-08-01

    We report the design and development of a friction force microscope for high-resolution studies in electrochemical environments. The design choices are motivated by the experimental requirements of atomic-scale friction measurements in liquids. The noise of the system is analyzed based on a methodology for the quantification of all the noise sources. The quantitative contribution of each noise source is analyzed in a series of lateral force measurements. Normal force detection is demonstrated in a study of the solvation potential in a confined liquid, octamethylcyclotetrasiloxane. The limitations of the timing resolution of the instrument are discussed in the context of an atomic stick-slip measurement. The instrument is capable of studying the atomic friction contrast between a bare Au(111) surface and a copper monolayer deposited at underpotential conditions in perchloric acid.

  10. Black holes, bandwidths and Beethoven

    Science.gov (United States)

    Kempf, Achim

    2000-04-01

    It is usually believed that a function φ(t) whose Fourier spectrum is bounded can vary at most as fast as its highest frequency component ωmax. This is, in fact, not the case, as Aharonov, Berry, and others drastically demonstrated with explicit counterexamples, so-called superoscillations. It has been claimed that even the recording of an entire Beethoven symphony can occur as part of a signal with a 1 Hz bandwidth. Bandlimited functions also occur as ultraviolet regularized fields. Their superoscillations have been suggested, for example, to resolve the trans-Planckian frequencies problem of black hole radiation. Here, we give an exact proof for generic superoscillations. Namely, we show that for every fixed bandwidth there exist functions that pass through any finite number of arbitrarily prespecified points. Further, we show that, in spite of the presence of superoscillations, the behavior of bandlimited functions can be characterized reliably, namely through an uncertainty relation: The standard deviation ΔT of samples φ(tn) taken at the Nyquist rate obeys ΔT>=1/4ωmax. This uncertainty relation generalizes to variable bandwidths. For ultraviolet regularized fields we identify the bandwidth as the in general spatially variable finite local density of degrees of freedom.

  11. High-Force Dielectric Electroactive Polymer (DEAP) membrane actuator

    Science.gov (United States)

    Hau, Steffen; York, Alexander; Seelecke, Stefan

    2016-04-01

    Energy efficiency, lightweight and scalability are key features for actuators in applications such as valves, pumps or any portable system. Dielectric electroactive Polymer (DEAP) technology is able to fulfill these requirements1 better than commonly used technology e.g. solenoids, but has limitations concerning force and stroke. However, the circular DEAP membrane actuator shows a potential increase in stroke in the mm range, when combined with an appropriate biasing mechanism2. Although, thus far, their force range is limited to the single-digit Newton range, or less3,4. This work describes how this force limit of DEAP membrane actuators can be pushed to the high double-digit Newton range and beyond. The concept for such an actuator consists of a stack of double-layered DEAPs membrane actuator combined with a biasing mechanism. These two components are combined in a novel way, which allows a compact design by integrating the biasing mechanism into the DEAP membrane actuator stack. Subsequently, the single components are manufactured, tested, and their force-displacement characteristic is documented. Utilizing this data allows assembling them into actuator systems for different applications. Two different actuators are assembled and tested (dimensions: 85x85x30mm3 (LxWxH)). The first one is able to lift 7.5kg. The second one can generate a force of 66N while acting against a spring load.

  12. High-speed adaptive contact-mode atomic force microscopy imaging with near-minimum-force.

    Science.gov (United States)

    Ren, Juan; Zou, Qingze

    2014-07-01

    In this paper, an adaptive contact-mode imaging approach is proposed to replace the traditional contact-mode imaging by addressing the major concerns in both the speed and the force exerted to the sample. The speed of the traditional contact-mode imaging is largely limited by the need to maintain precision tracking of the sample topography over the entire imaged sample surface, while large image distortion and excessive probe-sample interaction force occur during high-speed imaging. In this work, first, the image distortion caused by the topography tracking error is accounted for in the topography quantification. Second, the quantified sample topography is utilized in a gradient-based optimization method to adjust the cantilever deflection set-point for each scanline closely around the minimal level needed for maintaining stable probe-sample contact, and a data-driven iterative feedforward control that utilizes a prediction of the next-line topography is integrated to the topography feeedback loop to enhance the sample topography tracking. The proposed approach is demonstrated and evaluated through imaging a calibration sample of square pitches at both high speeds (e.g., scan rate of 75 Hz and 130 Hz) and large sizes (e.g., scan size of 30 μm and 80 μm). The experimental results show that compared to the traditional constant-force contact-mode imaging, the imaging speed can be increased by over 30 folds (with the scanning speed at 13 mm/s), and the probe-sample interaction force can be reduced by more than 15% while maintaining the same image quality.

  13. Tunable-Bandwidth Filter System

    Science.gov (United States)

    Aye, Tin; Yu, Kevin; Dimov, Fedor; Savant, Gajendra

    2006-01-01

    A tunable-bandwidth filter system (TBFS), now undergoing development, is intended to be part of a remote-sensing multispectral imaging system that will operate in the visible and near infrared spectral region (wavelengths from 400 to 900 nm). Attributes of the TBFS include rapid tunability of the pass band over a wide wavelength range and high transmission efficiency. The TBFS is based on a unique integration of two pairs of broadband Raman reflection holographic filters with two rotating spherical lenses. In experiments, a prototype of the TBFS was shown to be capable of spectral sampling of images in the visible range over a 200-nm spectral range with a spectral resolution of .30 nm. The figure depicts the optical layout of a prototype of the TBFS as part of a laboratory multispectral imaging system for the spectral sampling of color test images in two orthogonal polarizations. Each pair of broadband Raman reflection holographic filters is mounted at an equatorial plane between two halves of a spherical lens. The two filters in each pair are characterized by steep spectral slopes (equivalently, narrow spectral edges), no ripple or side lobes in their pass bands, and a few nanometers of non-overlapping wavelength range between their pass bands. Each spherical lens and thus the filter pair within it is rotated in order to rapidly tune its pass band. The rotations of the lenses are effected by electronically controlled, programmable, high-precision rotation stages. The rotations are coordinated by electronic circuits operating under overall supervision of a personal computer in order to obtain the desired variation of the overall pass bands with time. Embedding the filters inside the spherical lenses increases the range of the hologram incidence angles, making it possible to continuously tune the pass and stop bands of the filters over a wider wavelength range. In addition, each spherical lens also serves as part of the imaging optics: The telephoto lens focuses

  14. High resolution atomic force microscopy of double-stranded RNA

    Science.gov (United States)

    Ares, Pablo; Fuentes-Perez, Maria Eugenia; Herrero-Galán, Elías; Valpuesta, José M.; Gil, Adriana; Gomez-Herrero, Julio; Moreno-Herrero, Fernando

    2016-06-01

    Double-stranded (ds) RNA mediates the suppression of specific gene expression, it is the genetic material of a number of viruses, and a key activator of the innate immune response against viral infections. The ever increasing list of roles played by dsRNA in the cell and its potential biotechnological applications over the last decade has raised an interest for the characterization of its mechanical properties and structure, and that includes approaches using Atomic Force Microscopy (AFM) and other single-molecule techniques. Recent reports have resolved the structure of dsDNA with AFM at unprecedented resolution. However, an equivalent study with dsRNA is still lacking. Here, we have visualized the double helix of dsRNA under near-physiological conditions and at sufficient resolution to resolve the A-form sub-helical pitch periodicity. We have employed different high-sensitive force-detection methods and obtained images with similar spatial resolution. Therefore, we show here that the limiting factors for high-resolution AFM imaging of soft materials in liquid medium are, rather than the imaging mode, the force between the tip and the sample and the sharpness of the tip apex.Double-stranded (ds) RNA mediates the suppression of specific gene expression, it is the genetic material of a number of viruses, and a key activator of the innate immune response against viral infections. The ever increasing list of roles played by dsRNA in the cell and its potential biotechnological applications over the last decade has raised an interest for the characterization of its mechanical properties and structure, and that includes approaches using Atomic Force Microscopy (AFM) and other single-molecule techniques. Recent reports have resolved the structure of dsDNA with AFM at unprecedented resolution. However, an equivalent study with dsRNA is still lacking. Here, we have visualized the double helix of dsRNA under near-physiological conditions and at sufficient resolution to

  15. Nuclear Forces and High-Performance Computing: The Perfect Match

    Energy Technology Data Exchange (ETDEWEB)

    Luu, T; Walker-Loud, A

    2009-06-12

    High-performance computing is now enabling the calculation of certain nuclear interaction parameters directly from Quantum Chromodynamics, the quantum field theory that governs the behavior of quarks and gluons and is ultimately responsible for the nuclear strong force. We briefly describe the state of the field and describe how progress in this field will impact the greater nuclear physics community. We give estimates of computational requirements needed to obtain certain milestones and describe the scientific and computational challenges of this field.

  16. Frequency response and bandwidth enhancement in Ge/Si avalanche photodiodes with over 840 GHz gain-bandwidth-product.

    Science.gov (United States)

    Zaoui, Wissem Sfar; Chen, Hui-Wen; Bowers, John E; Kang, Yimin; Morse, Mike; Paniccia, Mario J; Pauchard, Alexandre; Campbell, Joe C

    2009-07-20

    In this work we report a separate-absorption-charge-multiplication Ge/Si avalanche photodiode with an enhanced gain-bandwidth-product of 845 GHz at a wavelength of 1310 nm. The corresponding gain value is 65 and the electrical bandwidth is 13 GHz at an optical input power of -30 dBm. The unconventional high gain-bandwidth-product is investigated using device physical simulation and optical pulse response measurement. The analysis of the electric field distribution, electron and hole concentration and drift velocities in the device shows that the enhanced gain-bandwidth-product at high bias voltages is due to a decrease of the transit time and avalanche build-up time limitation at high fields.

  17. Black Holes, Bandwidths and Beethoven

    OpenAIRE

    Kempf, A.

    1999-01-01

    It is usually believed that a function whose Fourier spectrum is bounded can vary at most as fast as its highest frequency component. This is in fact not the case, as Aharonov, Berry and others drastically demonstrated with explicit counter examples, so-called superoscillations. It has been claimed that even the recording of an entire Beethoven symphony can occur as part of a signal with 1Hz bandwidth. Bandlimited functions also occur as ultraviolet regularized fields. Their superoscillations...

  18. Utility-based bandwidth allocation algorithm for heterogeneous wireless networks

    Institute of Scientific and Technical Information of China (English)

    CHAI Rong; WANG XiuJuan; CHEN QianBin; SVENSSON Tommy

    2013-01-01

    In next generation wireless network (NGWN), mobile users are capable of connecting to the core network through various heterogeneous wireless access networks, such as cellular network, wireless metropolitan area network (WMAN), wireless local area network (WLAN), and ad hoc network. NGWN is expected to provide high-bandwidth connectivity with guaranteed quality-of-service to mobile users in a seamless manner; however, this desired function demands seamless coordination of the heterogeneous radio access network (RAN) technologies. In recent years, some researches have been conducted to design radio resource management (RRM) architectures and algorithms for NGWN; however, few studies stress the problem of joint network performance optimization, which is an essential goal for a cooperative service providing scenario. Furthermore, while some authors consider the competition among the service providers, the QoS requirements of users and the resource competition within access networks are not fully considered. In this paper, we present an interworking integrated network architecture, which is responsible for monitoring the status information of different radio access technologies (RATs) and executing the resource allocation algorithm. Within this architecture, the problem of joint bandwidth allocation for heterogeneous integrated networks is formulated based on utility function theory and bankruptcy game theory. The proposed bandwidth allocation scheme comprises two successive stages, i.e., service bandwidth allocation and user bandwidth allocation. At the service bandwidth allocation stage, the optimal amount of bandwidth for different types of services in each network is allocated based on the criterion of joint utility maximization. At the user bandwidth allocation stage, the service bandwidth in each network is optimally allocated among users in the network according to bankruptcy game theory. Numerical results demonstrate the efficiency of

  19. Challenges in Polybinary Modulation for Bandwidth Limited Optical Links

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Tafur Monroy, Idelfonso; Madsen, Peter

    2016-01-01

    Optical links using traditional modulation formats are reaching a plateau in terms of capacity, mainly due to bandwidth limitations in the devices employed at the transmitter and receivers. Advanced modulation formats, which boost the spectral efficiency, provide a smooth migration path towards...... of the current research status of the key building blocks in polybinary systems. The results clearly show how polybinary modulation effectively reduces the bandwidth requirements on optical links while providing high spectral efficiency....

  20. Casimir force between δ -δ' mirrors transparent at high frequencies

    Science.gov (United States)

    Braga, Alessandra N.; Silva, Jeferson Danilo L.; Alves, Danilo T.

    2016-12-01

    We investigate, in the context of a real massless scalar field in 1 +1 dimensions, models of partially reflecting mirrors simulated by Dirac δ -δ' point interactions. In the literature, these models do not exhibit full transparency at high frequencies. In order to provide a more realistic feature for these models, we propose a modified δ -δ' point interaction that enables full transparency in the limit of high frequencies. Taking this modified δ -δ' model into account, we investigate the Casimir force, comparing our results with those found in the literature.

  1. Algorithms and Requirements for Measuring Network Bandwidth

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Guojun

    2002-12-08

    This report unveils new algorithms for actively measuring (not estimating) available bandwidths with very low intrusion, computing cross traffic, thus estimating the physical bandwidth, provides mathematical proof that the algorithms are accurate, and addresses conditions, requirements, and limitations for new and existing algorithms for measuring network bandwidths. The paper also discusses a number of important terminologies and issues for network bandwidth measurement, and introduces a fundamental parameter -Maximum Burst Size that is critical for implementing algorithms based on multiple packets.

  2. Improving the Bandwidth Selection in Kernel Equating

    Science.gov (United States)

    Andersson, Björn; von Davier, Alina A.

    2014-01-01

    We investigate the current bandwidth selection methods in kernel equating and propose a method based on Silverman's rule of thumb for selecting the bandwidth parameters. In kernel equating, the bandwidth parameters have previously been obtained by minimizing a penalty function. This minimization process has been criticized by practitioners…

  3. 47 CFR 2.202 - Bandwidths.

    Science.gov (United States)

    2010-10-01

    ... RULES AND REGULATIONS Emissions § 2.202 Bandwidths. (a) Occupied bandwidth. The frequency bandwidth such.... Facsimile Analogue facsimile by sub-carrier frequency modulation of a single-sideband emission with reduced...: 1980 Hz=1.98 kHz 1K98F3C 5. Composite Emissions (See Table III-B) Radio-relay system,...

  4. Dynamic bandwidth allocation in GPON networks

    DEFF Research Database (Denmark)

    Ozimkiewiez, J.; Ruepp, Sarah Renée; Dittmann, Lars

    2009-01-01

    Two Dynamic Bandwidth Allocation algorithms used for coordination of the available bandwidth between end users in a GPON network have been simulated using OPNET to determine and compare the performance, scalability and efficiency of status reporting and non status reporting dynamic bandwidth allo...

  5. High resolution, large deformation 3D traction force microscopy.

    Science.gov (United States)

    Toyjanova, Jennet; Bar-Kochba, Eyal; López-Fagundo, Cristina; Reichner, Jonathan; Hoffman-Kim, Diane; Franck, Christian

    2014-01-01

    Traction Force Microscopy (TFM) is a powerful approach for quantifying cell-material interactions that over the last two decades has contributed significantly to our understanding of cellular mechanosensing and mechanotransduction. In addition, recent advances in three-dimensional (3D) imaging and traction force analysis (3D TFM) have highlighted the significance of the third dimension in influencing various cellular processes. Yet irrespective of dimensionality, almost all TFM approaches have relied on a linear elastic theory framework to calculate cell surface tractions. Here we present a new high resolution 3D TFM algorithm which utilizes a large deformation formulation to quantify cellular displacement fields with unprecedented resolution. The results feature some of the first experimental evidence that cells are indeed capable of exerting large material deformations, which require the formulation of a new theoretical TFM framework to accurately calculate the traction forces. Based on our previous 3D TFM technique, we reformulate our approach to accurately account for large material deformation and quantitatively contrast and compare both linear and large deformation frameworks as a function of the applied cell deformation. Particular attention is paid in estimating the accuracy penalty associated with utilizing a traditional linear elastic approach in the presence of large deformation gradients.

  6. High resolution, large deformation 3D traction force microscopy.

    Directory of Open Access Journals (Sweden)

    Jennet Toyjanova

    Full Text Available Traction Force Microscopy (TFM is a powerful approach for quantifying cell-material interactions that over the last two decades has contributed significantly to our understanding of cellular mechanosensing and mechanotransduction. In addition, recent advances in three-dimensional (3D imaging and traction force analysis (3D TFM have highlighted the significance of the third dimension in influencing various cellular processes. Yet irrespective of dimensionality, almost all TFM approaches have relied on a linear elastic theory framework to calculate cell surface tractions. Here we present a new high resolution 3D TFM algorithm which utilizes a large deformation formulation to quantify cellular displacement fields with unprecedented resolution. The results feature some of the first experimental evidence that cells are indeed capable of exerting large material deformations, which require the formulation of a new theoretical TFM framework to accurately calculate the traction forces. Based on our previous 3D TFM technique, we reformulate our approach to accurately account for large material deformation and quantitatively contrast and compare both linear and large deformation frameworks as a function of the applied cell deformation. Particular attention is paid in estimating the accuracy penalty associated with utilizing a traditional linear elastic approach in the presence of large deformation gradients.

  7. Characterization of Mn-modified Pb(Mg(13)Nb(23))O(3)-PbZrO(3)-PbTiO(3) single crystals for high power broad bandwidth transducers.

    Science.gov (United States)

    Zhang, Shujun; Lee, Sung-Min; Kim, Dong-Ho; Lee, Ho-Yong; Shrout, Thomas R

    2008-09-22

    The effect of MnO(2) addition on the dielectric and piezoelectric properties of 0.4Pb(Mg(13)Nb(23))O(3)-0.25PbZrO(3)-0.35PbTiO(3) single crystals was investigated. Analogous to acceptor doping in "hard" Pb(Zr,Ti)O(3) based polycrystalline materials, the Mn doped crystals exhibited enhanced mechanical Q ( approximately 1050) with low dielectric loss ( approximately 0.2%), while maintaining ultrahigh electromechanical coupling k(33)>90%, inherent in domain engineered single crystals. The effect of acceptor doping was also evident in the build-up of an internal bias (E(i) approximately 1.6 kVcm), shown by a horizontal offset in the polarization-field behavior. Together with the relatively high usage temperature (T(R-T) approximately 140 degrees C), the Mn doped crystals are promising candidates for high power and broad bandwidth transducers.

  8. Improvement of CBQ for bandwidth reclamation of RPR

    Science.gov (United States)

    Huang, Benxiong; Wang, Xiaoling; Xu, Ming; Shi, Lili

    2004-04-01

    The Resilient Packet Ring (RPR) IEEE 802.17 standard is under development as a new high-speed backbone technology for metropolitan area networks (MAN) [1]. Bandwidth reclamation has been concerned in RPR specifications from draft 0.1 to draft 2.4. According to specifications, allocated bandwidth can be reused, or reclaimed, by a lower priority service class whenever the reclamation does not effect the service guarantees of any equal or higher priority classes on the local station or on any other station on the ring [2]. The class-based queuing (CBQ) algorithm is proposed to implement link-sharing [3]. A hierarchical link-sharing structure can be used to specify guidelines for the distribution of 'excess" bandwidth [4] and it can rate-limit all classes to their allocated bandwidth. There is some sameness between the link-sharing of CBQ and bandwidth reclamation of RPR. The CBQ is a mature technology while RPR is a new technology. Given CBQ improvement and full use so as to make its thought suitable for bandwidth reclamation of RPR is the focus of our work. In this paper, we present the solution that can solve the reclamation problem, which proves to be effective by simulation.

  9. Federal Plan for High-End Computing. Report of the High-End Computing Revitalization Task Force (HECRTF)

    Science.gov (United States)

    2004-07-01

    and other energy feedstock more efficiently. Signal Transduction Pathways Develop atomic-level computational models and simulations of complex...biomolecules to explain and predict cell signal pathways and their disrupters. Yield understanding of initiation of cancer and other diseases and their...calculations also introduces a requirement for a high degree of internodal connectivity (high bisection bandwidth). These needs cannot be met simply by

  10. High resolution magnetic imaging: MicroSQUID Force Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hasselbach, K; Ladam, C; Dolocan, V O; Hykel, D; Crozes, T [Institut Neel, CNRS et Universite Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Schuster, K [Institut de RadioAstronomie Millimetrique 300 rue de la Piscine, Domaine Universitaire F-38406 Saint Martin d' Heres (France); Mailly, D [Laboratoire de Photonique et de Nanostructures, CNRS, Site Alcatel de Marcoussis Route de Nozay F-91460 Marcoussis (France)], E-mail: klaus.hasselbach@grenoble.cnrs.fr

    2008-02-01

    Magnetic imaging at the micrometer scale with high sensitivity is a challenge difficult to be met. Magnetic force microscopy has a very high spatial resolution but is limited in magnetic resolution. Hall probe microscopy is very powerful but sensor fabrication at the one micron scale is difficult and effects due to discreteness of charge appear in the form of significant 1/f noise. SQUID microscopy is very powerful, having high magnetic resolution, but spatial resolution is usually of the order of 10 {mu}m. The difficulties lay mostly in an efficient way to couple flux to the sensor. The only way to improve spatial resolution is to place the probe close to the very edge of the support, thus maximising coupling and spatial resolution. If there has been found a way to bring close the tip, there must be also found a reliable a way to maintain distance during scanning. We want to present recent improvements on scanning microsquid microscopy: Namely the improved fabrication of microSQUID tips using silicon micro machining and the precise positioning of the micrometer diameter microSQUID loop by electron beam lithography. The microSQUID is a microbridge DC SQUID, with two opposite microbridges. The constrictions are patterned by high-resolution e-beam lithography and have a width of 20 nm and a length of about 100 nm. The distance control during scanning is obtained by integrating the microSQUID sensor with a piezoelectric tuning fork acting as a force sensor allowing to control height and even topographic imaging. The detector is placed in a custom built near field microscope and the sample temperature can be varied between 0.1 Kelvin and 10 K. The microscope is used to study magnetic flux structures in unconventional superconductors and will be used to observe thermal domains in superconducting detectors in the voltage state.

  11. Quadrature phase interferometer for high resolution force spectroscopy

    CERN Document Server

    Paolino, Pierdomenico; Bellon, Ludovic

    2013-01-01

    In this article, we present a deflection measurement setup for Atomic Force Microscopy (AFM). It is based on a quadrature phase differential interferometer: we measure the optical path difference between a laser beam reflecting above the cantilever tip and a reference beam reflecting on the static base of the sensor. A design with very low environmental susceptibility and another allowing calibrated measurements on a wide spectral range are described. Both enable a very high resolution (down to $2.5E-15 m/sqrt{Hz}$), illustrated by a thermal noise measurement on an AFM cantilever. A quick review shows that our precision is equaling or outperforming the best results reported in the literature, but for a much larger deflection range, up to a few microns.

  12. Miniature High-Force, Long-Stroke SMA Linear Actuators

    Science.gov (United States)

    Cummin, Mark A.; Donakowski, William; Cohen, Howard

    2008-01-01

    Improved long-stroke shape-memory-alloy (SMA) linear actuators are being developed to exert significantly higher forces and operate at higher activation temperatures than do prior SMA actuators. In these actuators, long linear strokes are achieved through the principle of displacement multiplication, according to which there are multiple stages, each intermediate stage being connected by straight SMA wire segments to the next stage so that relative motions of stages are additive toward the final stage, which is the output stage. Prior SMA actuators typically include polymer housings or shells, steel or aluminum stages, and polymer pads between successive stages of displacement-multiplication assemblies. Typical output forces of prior SMA actuators range from 10 to 20 N, and typical strokes range from 0.5 to 1.5 cm. An important disadvantage of prior SMA wire actuators is relatively low cycle speed, which is related to actuation temperature as follows: The SMA wires in prior SMA actuators are typically made of a durable nickel/titanium alloy that has a shape-memory activation temperature of 80 C. An SMA wire can be heated quickly from below to above its activation temperature to obtain a stroke in one direction, but must then be allowed to cool to somewhat below its activation temperature (typically, less than or equal to 60 C in the case of an activation temperature of 80 C) to obtain a stroke in the opposite direction (return stroke). At typical ambient temperatures, cooling times are of the order of several seconds. Cooling times thus limit cycle speeds. Wires made of SMA alloys having significantly higher activation temperatures [denoted ultra-high-temperature (UHT) SMA alloys] cool to the required lower return-stroke temperatures more rapidly, making it possible to increase cycle speeds. The present development is motivated by a need, in some applications (especially aeronautical and space-flight applications) for SMA actuators that exert higher forces, operate

  13. Ptychography with broad-bandwidth radiation

    Energy Technology Data Exchange (ETDEWEB)

    Enders, B., E-mail: bjoern.enders@ph.tum.de; Dierolf, M.; Stockmar, M.; Pfeiffer, F. [Lehrstuhl für Biomedizinische Physik, Physik-Department and Institut für Medizintechnik, Technische Universität München, 85747 Garching (Germany); Cloetens, P. [European Synchrotron Radiation Facility, 38043 Grenoble (France); Thibault, P. [Department of Physics and Astronomy, University College London, London (United Kingdom)

    2014-04-28

    Ptychography, a scanning Coherent Diffractive Imaging (CDI) technique, has quickly gained momentum as a robust method to deliver quantitative images of extended specimens. A current conundrum for the development of X-ray CDI is the conflict between a need for higher flux to reach higher resolutions and the requirement to strongly filter the incident beam to satisfy the tight coherence prerequisite of the technique. Latest developments in algorithmic treatment of ptychographic data indicate that the technique is more robust than initially assumed, so that some experimental limitations can be substantially relaxed. Here, we demonstrate that ptychography can be conducted in conditions that were up to now considered insufficient, using a broad-bandwidth X-ray beam and an integrating scintillator-based detector. Our work shows the wide applicability of ptychography and paves the way to high-throughput, high-flux diffractive imaging.

  14. Controlling Laser Plasma Instabilities Using Temporal Bandwidth

    Science.gov (United States)

    Tsung, Frank; Weaver, J.; Lehmberg, R.

    2016-10-01

    We are performing particle-in-cell simulations using the code OSIRIS to study the effects of laser plasma interactions in the presence of temporal bandwidth under conditions relevant to current and future experiments on the NIKE laser. Our simulations show that, for sufficiently large bandwidth (where the inverse bandwidth is comparable with the linear growth time), the saturation level, and the distribution of hot electrons, can be effected by the addition of temporal bandwidths (which can be accomplished in experiments using beam smoothing techniques such as ISI). We will quantify these effects and investigate higher dimensional effects such as laser speckles. This work is supported by DOE and NRL.

  15. The Properties of Light Pressure Force with High Order in Laser Fields

    Institute of Scientific and Technical Information of China (English)

    陈险峰; 方建兴; 朱士群

    2002-01-01

    In this paper, the light pressure force in low and high intensity laser fields is derived. The exact numerical results of forces Fn∥(n=0,1,2,3,4,5,6…) through the matrix continued fraction method are presented. At low intensity field (G=1), the spatially averaged force F0∥ gives a cooling effect at the negative detuning. At high intensity (G=64), the effects of the forces with higher order (n≥2) appear and the contributes of the forces with odd or even order are opposite. It is great different from no high order force at low intensity.

  16. An Array Consisting of 10 High-Speed Side-Illuminated Evanescently Coupled Waveguide Photodetectors Each with a Bandwidth of 20 GHz

    Science.gov (United States)

    Lv, Qian-Qian; Ye, Han; Yin, Dong-Dong; Yang, Xiao-Hong; Han, Qin

    2015-12-01

    Not Available Supported by the High-Tech Research and Development Program of China under Grant Nos 2013AA031401, 2015AA016902 and 2015AA016904, the National Natural Science Foundation of China under Grant Nos 61176053, 61274069 and 61435002, and the National Basic Research Program of China under Grant No 2012CB933503.

  17. Response of thermosphere density to high-latitude forcing

    Science.gov (United States)

    Yamazaki, Y.; Kosch, M. J.; Vickers, H.; Sutton, E. K.; Ogawa, Y.

    2014-12-01

    Solar wind-magnetospheric disturbances cause enhancements in the energy input to the high-latitude upper atmosphere through particle precipitation and Joule heating. As the upper atmosphere is heated and expanded during geomagnetically disturbed periods, the neutral density in the thermosphere increases at a fixed altitude. Conversely, the thermosphere contracts during the recovery phase of the disturbance, resulting in a decrease of the density. The main objectives of this study are (1) to determine the morphology of the global thermospheric density response to high-latitude forcing, and (2) to determine the recovery speed of the thermosphere density after geomagnetic disturbances. For (1), we use thermospheric density data measured by the Challenging Minisatellite Payload (CHAMP) satellite during 2000-2010. It is demonstrated that the density enhancement during disturbed periods occurs first in the dayside cusp region, and the density at other regions slowly follows it. The reverse process is observed when geomagnetic activity ceases; the density enhancement in the cusp region fades away first, then the global density slowly goes back to the quiet level. For (2), we analyze EISCAT Svalbard radar and Tromso UHF radar data to estimate thermospheric densities during the recovery phase of geomagnetic disturbances. We attempt to determine the time constant for the density recovery both inside and outside the cusp region.

  18. Cryogenic Impinging Jets Subjected to High Frequency Transverse Acoustic Forcing in a High Pressure Environment

    Science.gov (United States)

    2016-07-27

    Forcing in a High Pressure Environment 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Mario Roa, S. Alex Schumaker...disclose the work. PA Clearance Number: 16308 Clearance Date: 6/17/2016 13. SUPPLEMENTARY NOTES For presentation at AIAA Propulsion and Energy; Salt...the coupling between the impact waves created by impinging jets and high frequency acoustic pressure perturbations. High speed, backlit imaging was

  19. Microphotonic Forces From Superfluid Flow

    CERN Document Server

    McAuslan, D L; Baker, C; Sachkou, Y; He, X; Sheridan, E; Bowen, W P

    2015-01-01

    In cavity optomechanics, radiation pressure and photothermal forces are widely utilized to cool and control micromechanical motion, with applications ranging from precision sensing and quantum information to fundamental science. Here, we realize an alternative approach to optical forcing based on superfluid flow and evaporation in response to optical heating. We demonstrate optical forcing of the motion of a cryogenic microtoroidal resonator at a level of 1.46 nN, roughly one order of magnitude larger than the radiation pressure force. We use this force to feedback cool the motion of a microtoroid mechanical mode to 137 mK. The photoconvective forces demonstrated here provide a new tool for high bandwidth control of mechanical motion in cryogenic conditions, and have the potential to allow efficient transfer of electromagnetic energy to motional kinetic energy.

  20. Improving the Bandwidth Utilization by Recycling the Unused Bandwidth in IEEE 802.16 Networks

    Directory of Open Access Journals (Sweden)

    Gowri T

    2012-03-01

    Full Text Available The Physical and MAC layers have been specified in IEEE 802.16 networks. The quality of service is ensured by the bandwidth reservation. The subscriber station should reserve the bandwidth more than its demand. But the bandwidth is fully utilized by SS but not all the time. So the bandwidth has recycled by the process of recycling the unused bandwidth. The main objective of the proposed scheme is to utilize the unused bandwidth by recycling and maintain the QOS service. By recycling the throughput can be improved which maintains the QOS in the proposed scheme. During this recycling process to maintain the QOS services, the amount of reserved bandwidth is not changed. The proposed scheme can utilize the unused bandwidth up to 70% on average. Protocols and the scheduling algorithms are used to improve the utilization and throughput.

  1. High-bandwidth AFM-based rheology is a sensitive indicator of early cartilage aggrecan degradation relevant to mouse models of osteoarthritis.

    Science.gov (United States)

    Nia, Hadi T; Gauci, Stephanie J; Azadi, Mojtaba; Hung, Han-Hwa; Frank, Eliot; Fosang, Amanda J; Ortiz, Christine; Grodzinsky, Alan J

    2015-01-02

    Murine models of osteoarthritis (OA) and post-traumatic OA have been widely used to study the development and progression of these diseases using genetically engineered mouse strains along with surgical or biochemical interventions. However, due to the small size and thickness of murine cartilage, the relationship between mechanical properties, molecular structure and cartilage composition has not been well studied. We adapted a recently developed AFM-based nano-rheology system to probe the dynamic nanomechanical properties of murine cartilage over a wide frequency range of 1 Hz to 10 kHz, and studied the role of glycosaminoglycan (GAG) on the dynamic modulus and poroelastic properties of murine femoral cartilage. We showed that poroelastic properties, highlighting fluid-solid interactions, are more sensitive indicators of loss of mechanical function compared to equilibrium properties in which fluid flow is negligible. These fluid-flow-dependent properties include the hydraulic permeability (an indicator of the resistance of matrix to fluid flow) and the high frequency modulus, obtained at high rates of loading relevant to jumping and impact injury in vivo. Utilizing a fibril-reinforced finite element model, we estimated the poroelastic properties of mouse cartilage over a wide range of loading rates for the first time, and show that the hydraulic permeability increased by a factor ~16 from knormal=7.80×10(-16)±1.3×10(-16) m(4)/N s to kGAG-depleted=1.26×10(-14)±6.73×10(-15) m(4)/N s after GAG depletion. The high-frequency modulus, which is related to fluid pressurization and the fibrillar network, decreased significantly after GAG depletion. In contrast, the equilibrium modulus, which is fluid-flow independent, did not show a statistically significant alteration following GAG depletion. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Highly sensitive wide bandwidth photodetector based on internal photoemission in CVD grown p-type MoS2/graphene Schottky junction.

    Science.gov (United States)

    Vabbina, PhaniKiran; Choudhary, Nitin; Chowdhury, Al-Amin; Sinha, Raju; Karabiyik, Mustafa; Das, Santanu; Choi, Wonbong; Pala, Nezih

    2015-07-22

    Two dimensional (2D) Molybdenum disulfide (MoS2) has evolved as a promising material for next generation optoelectronic devices owing to its unique electrical and optical properties, such as band gap modulation, high optical absorption, and increased luminescence quantum yield. The 2D MoS2 photodetectors reported in the literature have presented low responsivity compared to silicon based photodetectors. In this study, we assembled atomically thin p-type MoS2 with graphene to form a MoS2/graphene Schottky photodetector where photo generated holes travel from graphene to MoS2 over the Schottky barrier under illumination. We found that the p-type MoS2 forms a Schottky junction with graphene with a barrier height of 139 meV, which results in high photocurrent and wide spectral range of detection with wavelength selectivity. The fabricated photodetector showed excellent photosensitivity with a maximum photo responsivity of 1.26 AW(-1) and a noise equivalent power of 7.8 × 10(-12) W/√Hz at 1440 nm.

  3. A Novel Dynamic Bandwidth Assignment Algorithm for Multi-Services EPONs

    Institute of Scientific and Technical Information of China (English)

    CHEN Xue; ZHANG Yang; HUANG Xiang; DENG Yu; SUN Shu-he

    2005-01-01

    In this paper we propose a novel Dynamic Bandwidth Assignment (DBA) algorithm for Ethernet-based Passive Optical Networks (EPON) which offers multiple kinds of services. To satisfy crucial Quality of Service (QoS) requirement for Time Division Multiplexing (TDM) service and achieve fair and high bandwidth utilization simultaneously, the algorithm integrates periodic, for TDM service, and polling granting for Ethernet service. Detailed simulation shows that the algorithm guarantees carrier-grade QoS for TDM service, high bandwidth utilization and good fairness of bandwidth assignment among Optical Network Units (ONU).

  4. Directing Traffic: Managing Internet Bandwidth Fairly

    Science.gov (United States)

    Paine, Thomas A.; Griggs, Tyler J.

    2008-01-01

    Educational institutions today face budgetary restraints and scarce resources, complicating the decision of how to allot bandwidth for campus network users. Additionally, campus concerns over peer-to-peer networking (specifically outbound Internet traffic) have increased because of bandwidth and copyright issues. In this article, the authors…

  5. 47 CFR 95.633 - Emission bandwidth.

    Science.gov (United States)

    2010-10-01

    ... SERVICES Technical Regulations Technical Standards § 95.633 Emission bandwidth. (a) The authorized... frequencies 151.820 MHz, 151.880 MHz, and 151.940 MHz are limited to 11.25 kHz. (2) Emissions on frequencies... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emission bandwidth. 95.633 Section...

  6. Energy Bandwidth for Petroleum Refining Processes

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2006-10-01

    The petroleum refining energy bandwidth report analyzes the most energy-intensive unit operations used in U.S. refineries: crude oil distillation, fluid catalytic cracking, catalytic hydrotreating, catalytic reforming, and alkylation. The "bandwidth" provides a snapshot of the energy losses that can potentially be recovered through best practices and technology R&D.

  7. Bandwidth engineering of photonic crystal waveguide bends

    DEFF Research Database (Denmark)

    Borel, Peter Ingo; Frandsen, Lars Hagedorn; Harpøth, Anders;

    2004-01-01

    An effective design principle has been applied to photonic crystal waveguide bends fabricated in silicon-on-insulator material using deep UV lithography resulting in a large increase in the low-loss bandwidth of the bends. Furthermore, it is experimentally demonstrated that the absolute bandwidth...

  8. Bimodal-sized quantum dots for broad spectral bandwidth emitter.

    Science.gov (United States)

    Zhou, Yinli; Zhang, Jian; Ning, Yongqiang; Zeng, Yugang; Zhang, Jianwei; Zhang, Xing; Qin, Li; Wang, Lijun

    2015-12-14

    In this work, a high-power and broadband superluminescent diode (SLD) is achieved utilizing bimodal-sized quantum dots (QDs) as active materials. The device exhibits a 3 dB bandwidth of 178.8 nm with output power of 1.3 mW under continuous-wave (CW) conditions. Preliminary discussion attributes the spectra behavior of the device to carrier transfer between small dot ensemble and large dot ensemble. Our result provides a new possibility to further broadening the spectral bandwidth and improving the CW output power of QD-SLDs.

  9. The differential effect of metabolic alkalosis on maximum force and rate of force development during repeated, high-intensity cycling.

    Science.gov (United States)

    Siegler, Jason C; Marshall, Paul W M; Raftry, Sean; Brooks, Cristy; Dowswell, Ben; Romero, Rick; Green, Simon

    2013-12-01

    The purpose of this investigation was to assess the influence of sodium bicarbonate supplementation on maximal force production, rate of force development (RFD), and muscle recruitment during repeated bouts of high-intensity cycling. Ten male and female (n = 10) subjects completed two fixed-cadence, high-intensity cycling trials. Each trial consisted of a series of 30-s efforts at 120% peak power output (maximum graded test) that were interspersed with 30-s recovery periods until task failure. Prior to each trial, subjects consumed 0.3 g/kg sodium bicarbonate (ALK) or placebo (PLA). Maximal voluntary contractions were performed immediately after each 30-s effort. Maximal force (F max) was calculated as the greatest force recorded over a 25-ms period throughout the entire contraction duration while maximal RFD (RFD max) was calculated as the greatest 10-ms average slope throughout that same contraction. F max declined similarly in both the ALK and PLA conditions, with baseline values (ALK: 1,226 ± 393 N; PLA: 1,222 ± 369 N) declining nearly 295 ± 54 N [95% confidence interval (CI) = 84-508 N; P force vs. maximum rate of force development during a whole body fatiguing task.

  10. Ion drag force in plasmas at high electronegativity.

    Science.gov (United States)

    Denysenko, I; Yu, M Y; Stenflo, L; Xu, S

    2005-07-01

    The electric as well as the positive- and negative-ion drag forces on an isolated dust grain in an electronegative plasma are studied for large negative-ion densities, when the negative ions are not Boltzmann distributed. The investigation is carried out for submicrometer dust particles, so that the theory of Coulomb scattering is applicable for describing ion-dust interaction. Among the forces acting on the dust grain, the negative-ion drag force is found to be important. The effects of the negative-ion density, neutral-gas pressure, and dust-grain size on the forces are also considered. It is shown that by increasing the density of the negative ions one can effectively manipulate the dust grains. Our results imply that both dust voids and balls can be formed.

  11. Precipitation-Strengthened, High-Temperature, High-Force Shape Memory Alloys

    Science.gov (United States)

    Noebe, Ronald D.; Draper, Susan L.; Nathal, Michael V.; Crombie, Edwin A.

    2008-01-01

    Shape memory alloys (SMAs) are an enabling component in the development of compact, lightweight, durable, high-force actuation systems particularly for use where hydraulics or electrical motors are not practical. However, commercial shape memory alloys based on NiTi are only suitable for applications near room temperature, due to their relatively low transformation temperatures, while many potential applications require higher temperature capability. Consequently, a family of (Ni,Pt)(sub 1-x)Ti(sub x) shape memory alloys with Ti concentrations ranging from about 15 to 25 at.% have been developed for applications in which there are requirements for SMA actuators to exert high forces at operating temperatures higher than those of conventional binary NiTi SMAs. These alloys can be heat treated in the range of 500 C to produce a series of fine precipitate phases that increase the strength of alloy while maintaining a high transformation temperature, even in Ti-lean compositions.

  12. Fundamental High-Speed Limits in Single-Molecule, Single-Cell, and Nanoscale Force Spectroscopies

    Science.gov (United States)

    2016-01-01

    Force spectroscopy is enhancing our understanding of single-biomolecule, single-cell, and nanoscale mechanics. Force spectroscopy postulates the proportionality between the interaction force and the instantaneous probe deflection. By studying the probe dynamics, we demonstrate that the total force acting on the probe has three different components: the interaction, the hydrodynamic, and the inertial. The amplitudes of those components depend on the ratio between the resonant frequency and the frequency at which the data are measured. A force–distance curve provides a faithful measurement of the interaction force between two molecules when the inertial and hydrodynamic components are negligible. Otherwise, force spectroscopy measurements will underestimate the value of unbinding forces. Neglecting the above force components requires the use of frequency ratios in the 50–500 range. These ratios will limit the use of high-speed methods in force spectroscopy. The theory is supported by numerical simulations. PMID:27359243

  13. A System Theoretic Approach to Bandwidth Estimation

    OpenAIRE

    Liebeherr, Jorg; Fidler, Markus; Valaee, Shahrokh

    2008-01-01

    It is shown that bandwidth estimation in packet networks can be viewed in terms of min-plus linear system theory. The available bandwidth of a link or complete path is expressed in terms of a {\\em service curve}, which is a function that appears in the network calculus to express the service available to a traffic flow. The service curve is estimated based on measurements of a sequence of probing packets or passive measurements of a sample path of arrivals. It is shown that existing bandwidth...

  14. Cryogenic Impinging Jets Subjected to High Frequency Transverse Acoustic Forcing in a High Pressure Environment

    Science.gov (United States)

    2016-07-27

    other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a ...Transverse Acoustic Forcing in a High Pressure Environment 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Mario...Briefing Charts 15. SUBJECT TERMS N/ A 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE

  15. Average Bandwidth Allocation Model of WFQ

    Directory of Open Access Journals (Sweden)

    Tomáš Balogh

    2012-01-01

    Full Text Available We present a new iterative method for the calculation of average bandwidth assignment to traffic flows using a WFQ scheduler in IP based NGN networks. The bandwidth assignment calculation is based on the link speed, assigned weights, arrival rate, and average packet length or input rate of the traffic flows. We prove the model outcome with examples and simulation results using NS2 simulator.

  16. Investigation of Diagonal Antenna-Chassis Mode in Mobile Terminal LTE MIMO Antennas for Bandwidth Enhancement

    DEFF Research Database (Denmark)

    Zhang, Shuai; Zhao, Kun; Ying, Zhinong

    2015-01-01

    A diagonal antenna-chassis mode is investigated in long-term evolution multiple-input-multiple-output (LTE MIMO) antennas. The MIMO bandwidth is defined in this paper as the overlap range of the low-envelope correlation coefficient, high total efficiency, and -6-dB impedance matching bandwidths...

  17. Nike Court Force High Lux 奢华外衣

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Nike这次将使用在Air Force1中惯用的Lux的处理手法重新包装经典的Court Force High,这两双球鞋分别采用了黑色和灰色的单色顶级绒面革物料制作鞋面。而Lux系列的标志则印制在球鞋的后跟处。这是一款设计简洁的球鞋,与时下流行的色彩潮流截然不同.也许反潮流而行之也是体现纯粹经典的好办法。

  18. Schottky Heterodyne Receivers With Full Waveguide Bandwidth

    Science.gov (United States)

    Hesler, Jeffrey; Crowe, Thomas

    2011-01-01

    Compact THz receivers with broad bandwidth and low noise have been developed for the frequency range from 100 GHz to 1 THz. These receivers meet the requirements for high-resolution spectroscopic studies of planetary atmospheres (including the Earth s) from spacecraft, as well as airborne and balloon platforms. The ongoing research is significant not only for the development of Schottky mixers, but also for the creation of a receiver system, including the LO chain. The new receivers meet the goals of high sensitivity, compact size, low total power requirement, and operation across complete waveguide bands. The exceptional performance makes these receivers ideal for the broader range of scientific and commercial applications. These include the extension of sophisticated test and measurement equipment to 1 THz and the development of low-cost imaging systems for security applications and industrial process monitoring. As a particular example, a WR-1.9SHM (400-600 GHz) has been developed (see Figure 1), with state-of-the-art noise temperature ranging from 1,000-1,800 K (DSB) over the full waveguide band. Also, a Vector Network Analyzer extender has been developed (see Figure 2) for the WR1.5 waveguide band (500 750 GHz) with 100-dB dynamic range.

  19. Bandwidth utilization maximization of scientific RF communication systems

    Energy Technology Data Exchange (ETDEWEB)

    Rey, D. [Sandia National Lab., Albuquerque, NM (United States); Ryan, W. [New Mexico State Univ., Las Cruces, NM (United States); Ross, M.

    1997-01-01

    A method for more efficiently utilizing the frequency bandwidth allocated for data transmission is presented. Current space and range communication systems use modulation and coding schemes that transmit 0.5 to 1.0 bits per second per Hertz of radio frequency bandwidth. The goal in this LDRD project is to increase the bandwidth utilization by employing advanced digital communications techniques. This is done with little or no increase in the transmit power which is usually very limited on airborne systems. Teaming with New Mexico State University, an implementation of trellis coded modulation (TCM), a coding and modulation scheme pioneered by Ungerboeck, was developed for this application and simulated on a computer. TCM provides a means for reliably transmitting data while simultaneously increasing bandwidth efficiency. The penalty is increased receiver complexity. In particular, the trellis decoder requires high-speed, application-specific digital signal processing (DSP) chips. A system solution based on the QualComm Viterbi decoder and the Graychip DSP receiver chips is presented.

  20. Efficient Bandwidth Management for Ethernet Passive Optical Networks

    KAUST Repository

    Elrasad, Amr Elsayed M.

    2016-05-15

    The increasing bandwidth demands in access networks motivates network operators, networking devices manufacturers, and standardization institutions to search for new approaches for access networks. These approaches should support higher bandwidth, longer distance between end user and network operator, and less energy consumption. Ethernet Passive Optical Network (EPON) is a favorable choice for broadband access networks. EPONs support transmission rates up to 10 Gbps. EPONs also support distance between end users and central office up to 20 Km. Moreover, optical networks have the least energy consumption among all types of networks. In this dissertation, we focus on reducing delay and saving energy in EPONs. Reducing delay is essential for delay-sensitive traffic, while minimizing energy consumption is an environmental necessity and also reduces the network operating costs. We identify five challenges, namely excess bandwidth allocation, frame delineation, congestion resolution, large round trip time delay in long-reach EPONs (LR-EPONs), and energy saving. We provide a Dynamic Bandwidth Allocation (DBA) approach for each challenge. We also propose a novel scheme that combines the features of the proposed approaches in one highly performing scheme. Our approach is to design novel DBA protocols that can further reduce the delay and be simultaneously simple and fair. We also present a dynamic bandwidth allocation scheme for Green EPONs taking into consideration maximizing energy saving under target delay constraints. Regarding excess bandwidth allocation, we develop an effective DBA scheme called Delayed Excess Scheduling (DES). DES achieves significant delay and jitter reduction and is more suitable for industrial deployment due to its simplicity. Utilizing DES in hybrid TDM/WDM EPONs (TWDM-EPONs) is also investigated. We also study eliminating the wasted bandwidth due to frame delineation. We develop an interactive DBA scheme, Efficient Grant Sizing Interleaved

  1. 未来高带宽网络中FAST TCP与TCP Vegas的公平性分析%Fairness analysis of FAST TCP and TCP Vegas over future high-bandwidth internet

    Institute of Scientific and Technical Information of China (English)

    朱小松

    2012-01-01

    FAST TCP, a modern end-to-end protocol adopting queuing delay as a congestion measure. However, the lack of a precise measurement of queuing delay leads to a potential unfairness problem that FAST TCP flows may be discriminated against according to their starting times in a persistent congestion scenario, TCP Vegas also encounters the unfairness problem. The unfairness problem is quantitatively assessed by mathematical analysis and ns2 simulations, then, we compared FAST TCP with TCP Vegas. Consequently, FAST TCP demonstrates a competitive edge over TCP Vegas, under future high bandwidth-delay product environment. This conclusion will contribute to the improvement of FAST TCP for future reference.%FAST TCP是先进的端到端拥塞控制协议,采用队列时延作为拥塞度量.由于不能准确测得精确的队列时延,此协议中存有不公平的隐患,即在某些持续拥塞场景下,不同时刻启动的FAST TCP流会受到差别对待,TCP Vegas中同样存在不公平问题.通过数学分析和ns2仿真对这种不公平问题进行量化,进而比较FASTTCP与TCP Vegas在公平性问题上的性能差异.结果证明了在将来高带宽时延乘积网络环境下,FAST TCP在公平性上要明显优于TCP Vegas.这为对FAST TCP协议的改进给出了有价值的参照.

  2. Passive Mobile Bandwidth Classification Using Short Lived TCP Connections

    OpenAIRE

    Michelinakis, Foivos; Kreitz, Gunnar; Petrocco, Riccardo; Zhang, Boxun; Widmer, Joerg

    2015-01-01

    Consumption of multimedia content is moving from a residential environment to mobile phones. Optimizing Quality of Experience—smooth, quick, and high quality playback—is more difficult in this setting, due to the highly dynamic nature of wireless links. A key requirement for achieving this goal is estimating the available bandwidth of mobile devices. Ideally, this should be done quickly and with low overhead. One challenge is that the majority of connections on mobiles are short-l...

  3. Attonewton force detection using microspheres in a dual-beam optical trap in high vacuum

    CERN Document Server

    Ranjit, Gambhir; Stutz, Jordan H; Cunningham, Mark; Geraci, Andrew A

    2015-01-01

    We describe the implementation of laser-cooled silica microspheres as force sensors in a dual-beam optical dipole trap in high vacuum. Using this system we have demonstrated trap lifetimes exceeding several days, attonewton force detection capability, and wide tunability in trapping and cooling parameters. Measurements have been performed with charged and neutral beads to calibrate the sensitivity of the detector. This work establishes the suitability of dual beam optical dipole traps for precision force measurement in high vacuum with long averaging times, and enables future applications including the study of gravitational inverse square law violations at short range, Casimir forces, acceleration sensing, and quantum opto-mechanics.

  4. Central fatigue of the first dorsal interosseous muscle during low-force and high-force sustained submaximal contractions.

    Science.gov (United States)

    Eichelberger, Tamara D; Bilodeau, Martin

    2007-09-01

    The aim of this study was to compare the extent of central fatigue in the first dorsal interosseous (FDI) muscle of healthy adults in low, moderate and high-force submaximal contractions. Nine healthy adults completed four experimental sessions where index finger abduction force was recorded during voluntary contractions and in response to brief trains (five pulses at 100 Hz) of electrical stimulation. The ability to maximally activate FDI under volition, or voluntary activation, and its change with sustained activity (central fatigue) was assessed using the twitch interpolation technique. The fatigue tasks consisted of continuous isometric index finger abduction contractions held until exhaustion at four target force levels: 30%, 45%, 60% and 75% of the maximal voluntary contraction. The main finding was the presence of central fatigue for the 30% task, but not for the three other fatigue tasks. The extent of central fatigue was also associated with changes in a measure reflecting the status of peripheral structures/mechanisms. It appears that central fatigue contributed to task failure for the lowest force fatigue task (30%), but not for the other (higher) contraction intensities.

  5. Large scale probabilistic available bandwidth estimation

    CERN Document Server

    Thouin, Frederic; Rabbat, Michael

    2010-01-01

    The common utilization-based definition of available bandwidth and many of the existing tools to estimate it suffer from several important weaknesses: i) most tools report a point estimate of average available bandwidth over a measurement interval and do not provide a confidence interval; ii) the commonly adopted models used to relate the available bandwidth metric to the measured data are invalid in almost all practical scenarios; iii) existing tools do not scale well and are not suited to the task of multi-path estimation in large-scale networks; iv) almost all tools use ad-hoc techniques to address measurement noise; and v) tools do not provide enough flexibility in terms of accuracy, overhead, latency and reliability to adapt to the requirements of various applications. In this paper we propose a new definition for available bandwidth and a novel framework that addresses these issues. We define probabilistic available bandwidth (PAB) as the largest input rate at which we can send a traffic flow along a pa...

  6. High-Throughput Atomic Force Microscopes Operating in Parallel

    CERN Document Server

    Sadeghian, H; Dekker, B; Winters, J; Bijnagte, T; Rijnbeek, R

    2016-01-01

    Atomic force microscopy (AFM) is an essential nanoinstrument technique for several applications such as cell biology and nanoelectronics metrology and inspection. The need for statistically significant sample sizes means that data collection can be an extremely lengthy process in AFM. The use of a single AFM instrument is known for its very low speed and not being suitable for scanning large areas, resulting in very-low-throughput measurement. We address this challenge by parallelizing AFM instruments. The parallelization is achieved by miniaturizing the AFM instrument and operating many of them simultaneously. This nanoinstrument has the advantages that each miniaturized AFM can be operated independently and that the advances in the field of AFM, both in terms of speed and imaging modalities, can be implemented more easily. Moreover, a parallel AFM instrument also allows one to measure several physical parameters simultaneously; while one instrument measures nano-scale topography, another instrument can meas...

  7. Construction and experimental testing of the constant-bandwidth constant-temperature anemometer.

    Science.gov (United States)

    Ligeza, P

    2008-09-01

    A classical constant-temperature hot-wire anemometer enables the measurement of fast-changing flow velocity fluctuations, although its transmission bandwidth is a function of measured velocity. This may be a source of significant dynamic errors. Incorporation of an adaptive controller into the constant-temperature system results in hot-wire anemometer operating with a constant transmission bandwidth. The construction together with the results of experimental testing of a constant-bandwidth hot-wire anemometer prototype are presented in this article. During the testing, an approximately constant transmission bandwidth of the anemometer was achieved. The constant-bandwidth hot-wire anemometer can be used in measurements of high-frequency variable flows characterized by a wide range of velocity changes.

  8. Reconstruction in Time-Bandwidth Compression Systems

    CERN Document Server

    Chan, Jacky; Asghari, Mohammad H; Jalali, Bahram

    2014-01-01

    Recently it has been shown that the intensity time-bandwidth product of optical signals can be engineered to match that of the data acquisition instrument. In particular, it is possible to slow down an ultrafast signal, resulting in compressed RF bandwidth - a similar benefit to that offered by the Time-Stretch Dispersive Fourier Transform (TS-DFT) - but with reduced temporal record length leading to time-bandwidth compression. The compression is implemented using a warped group delay dispersion leading to non-uniform time stretching of the signal's intensity envelope. Decoding requires optical phase retrieval and reconstruction of the input temporal profile, for the case where information of interest is resides in the complex field. In this paper, we present results on the general behavior of the reconstruction process and its dependence on the signal-to-noise ratio. We also discuss the role of chirp in the input signal.

  9. Large-bandwidth planar photonic crystal waveguides

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Lavrinenko, Andrei

    2002-01-01

    A general design principle is presented for making finite-height photonic crystal waveguides that support leakage-free guidance of light over large frequency intervals. The large bandwidth waveguides are designed by introducing line defects in photonic crystal slabs, where the material in the lin......-free single-mode guidance is found for a large frequency interval covering 60% of the photonic band-gap.......A general design principle is presented for making finite-height photonic crystal waveguides that support leakage-free guidance of light over large frequency intervals. The large bandwidth waveguides are designed by introducing line defects in photonic crystal slabs, where the material in the line...... defect has appropriate dispersion properties relative to the photonic crystal slab material surrounding the line defect. A three-dimensional theoretical analysis is given for large-bandwidth waveguide designs based on a silicon-air photonic crystal slab suspended in air. In one example, the leakage...

  10. Bandwidth Assessment for MultiRotor UAVs

    Directory of Open Access Journals (Sweden)

    Ferrarese Gastone

    2017-06-01

    Full Text Available This paper is a technical note about the theoretical evaluation of the bandwidth of multirotor helicopters. Starting from a mathematical linear model of the dynamics of a multirotor aircraft, the transfer functions of the state variables that deeply affect the stability characteristics of the aircraft are obtained. From these transfer functions, the frequency response analysis of the system is effected. After this analysis, the bandwidth of the system is defined. This result is immediately utilized for the design of discrete PID controllers for hovering flight stabilization. Numeric simulations are shown to demonstrate that the knowledge of the bandwidth is a valid aid in the design of flight control systems of these machines.

  11. Improved space bandwidth product in image upconversion

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin; Pedersen, Christian; Tidemand-Lichtenberg, Peter

    2012-01-01

    We present a technique increasing the space bandwidth product of a nonlinear image upconversion process used for spectral imaging. The technique exploits the strong dependency of the phase-matching condition in sum frequency generation (SFG) on the angle of propagation of the interacting fields...... with respect to the optical axis. Appropriate scanning of the phase-match condition (Δk=0) while acquiring images, allow us to perform monochromatic image reconstruction with a significantly increased space bandwidth product. We derive the theory for the image reconstruction process and demonstrate acquisition...... of images with >10 fold increase in space bandwidth product, i.e. the number of pixel elements, when compared to upconversion of images using fixed phase-match conditions....

  12. Long-pulse-width narrow-bandwidth solid state laser

    Science.gov (United States)

    Dane, C.B.; Hackel, L.A.

    1997-11-18

    A long pulse laser system emits 500-1000 ns quasi-rectangular pulses at 527 nm with near diffraction-limited divergence and near transform-limited bandwidth. The system consists of one or more flashlamp-pumped Nd:glass zig-zag amplifiers, a very low threshold stimulated-Brillouin-scattering (SBS) phase conjugator system, and a free-running single frequency Nd:YLF master oscillator. Completely passive polarization switching provides eight amplifier gain passes. Multiple frequency output can be generated by using SBS cells having different pressures of a gaseous SBS medium or different SBS materials. This long pulse, low divergence, narrow-bandwidth, multi-frequency output laser system is ideally suited for use as an illuminator for long range speckle imaging applications. Because of its high average power and high beam quality, this system has application in any process which would benefit from a long pulse format, including material processing and medical applications. 5 figs.

  13. Exploiting material softening in hard PZTs for resonant bandwidth enhancement

    Science.gov (United States)

    Leadenham, S.; Moura, A.; Erturk, A.

    2016-04-01

    Intentionally designed nonlinearities have been employed by several research groups to enhance the frequency bandwidth of vibration energy harvesters. Another type of nonlinear resonance behavior emerges from the piezoelectric constitutive behavior for high excitation levels and is manifested in the form of softening stiffness. This material nonlinearity does not result in the jump phenomenon in soft piezoelectric ceramics, e.g. PZT-5A and PZT-5H, due to their large internal dissipation. This paper explores the potential for wideband energy harvesting using a hard (relatively high quality factor) PZT-8 bimorph by exploiting its material softening. A wide range of base excitation experiments conducted for a set of resistive electrical loads confirms the frequency bandwidth enhancement.

  14. Bandwidth Reservation Using Velocity and Handoff Statistics for Cellular Networks

    Institute of Scientific and Technical Information of China (English)

    Chuan-Lin Zhang; Kam Yiu Lam; Wei-Jia Jia

    2006-01-01

    The percentages of blocking and forced termination rates as parameters representing quality of services (QoS)requirements are presented. The relation between the connection statistics of mobile users in a cell and the handoff number and new call number in next duration in each cell is explored. Based on the relation, statistic reservation tactics are raised.The amount of bandwidth for new calls and handoffs of each cell in next period is determined by using the strategy. Using this method can guarantee the communication system suits mobile connection request dynamic. The QoS parameters:forced termination rate and blocking rate can be maintained steadily though they may change with the offered load. Some numerical experiments demonstrate this is a practical method with affordable overhead.

  15. Large-bandwidth planar photonic crystal waveguides

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Lavrinenko, Andrei

    2002-01-01

    A general design principle is presented for making finite-height photonic crystal waveguides that support leakage-free guidance of light over large frequency intervals. The large bandwidth waveguides are designed by introducing line defects in photonic crystal slabs, where the material in the line...... defect has appropriate dispersion properties relative to the photonic crystal slab material surrounding the line defect. A three-dimensional theoretical analysis is given for large-bandwidth waveguide designs based on a silicon-air photonic crystal slab suspended in air. In one example, the leakage...

  16. Real-Time Virtual Instruments for Remote Sensor Monitoring Using Low Bandwidth Wireless Networks

    Directory of Open Access Journals (Sweden)

    Biruk Gebre

    2008-06-01

    Full Text Available The development of a peer-to-peer virtual instrumentation system for remote acquisition, analysis and transmission of data on low bandwidth networks is described. The objective of this system is to collect high frequency/high bandwidth data from multiple sensors placed at remote locations and adaptively adjust the resolution of this data so that it can be transmitted on bandwidth limited networks to a central monitoring and command center. This is achieved by adaptively re-sampling (decimating the data from the sensors at the remote location before transmission. The decimation is adjusted to the available bandwidth of the communications network which is characterized in real-time. As a result, the system allows users at the remote command center to view high bandwidth data (at a lower resolution with user-aware and minimized latency. This technique is applied to an eight hydrophone data acquisition system that requires a 25.6 Mbps connection for the transmission of the full data set using a wireless connection with 1 – 3.5 Mbps variable bandwidth. This technique can be used for applications that require monitoring of high bandwidth data from remote sensors in research and education fields such as remote scientific instruments and visually driven control applications.

  17. Real-Time Virtual Instruments for Remote Sensor Monitoring Using Low Bandwidth Wireless Networks

    Directory of Open Access Journals (Sweden)

    Biruk Gebre

    2008-06-01

    Full Text Available The development of a peer-to-peer virtual instrumentation system for remote acquisition, analysis and transmission of data on low bandwidth networks is described. The objective of this system is to collect high frequency/high bandwidth data from multiple sensors placed at remote locations and adaptively adjust the resolution of this data so that it can be transmitted on bandwidth limited networks to a central monitoring and command center. This is achieved by adaptively re-sampling (decimating the data from the sensors at the remote location before transmission. The decimation is adjusted to the available bandwidth of the communications network which is characterized in real-time. As a result, the system allows users at the remote command center to view high bandwidth data (at a lower resolution with user-aware and minimized latency. This technique is applied to an eight hydrophone data acquisition system that requires a 25.6 Mbps connection for the transmission of the full data set using a wireless connection with 1 – 3.5 Mbps variable bandwidth. This technique can be used for applications that require monitoring of high bandwidth data from remote sensors in research and education fields such as remote scientific instruments and visually driven control applications.

  18. High resolution magnetic force microscopy using focused ion beam modified tips

    NARCIS (Netherlands)

    Phillips, G.N.; Siekman, M.H.; Abelmann, L.; Lodder, J.C.

    2002-01-01

    Atomic force microscope tips coated by the thermal evaporation of a magnetic 30 nm thick Co film have been modified by focused ion beam milling with Ga+ ions to produce tips suitable for magnetic force microscopy. Such tips possess a planar magnetic element with high magnetic shape anisotropy, an ex

  19. Calculating levitation forces in the magnet-high-temperature superconductor systems

    NARCIS (Netherlands)

    Ermolaev, YS; Rudnev, IA

    2005-01-01

    A new method of calculation of the magnetic levitation force in the permanent magnet-high-temperature superconductor systems is proposed based on the Maxwell equations and the Bean model. The dependences of the levitation force on the gap width calculated for various regimes of superconductor coolin

  20. Calculating levitation forces in the magnet-high-temperature superconductor systems

    NARCIS (Netherlands)

    Ermolaev, YS; Rudnev, IA

    2005-01-01

    A new method of calculation of the magnetic levitation force in the permanent magnet-high-temperature superconductor systems is proposed based on the Maxwell equations and the Bean model. The dependences of the levitation force on the gap width calculated for various regimes of superconductor coolin

  1. High-throughput atomic force microscopes operating in parallel

    Science.gov (United States)

    Sadeghian, Hamed; Herfst, Rodolf; Dekker, Bert; Winters, Jasper; Bijnagte, Tom; Rijnbeek, Ramon

    2017-03-01

    Atomic force microscopy (AFM) is an essential nanoinstrument technique for several applications such as cell biology and nanoelectronics metrology and inspection. The need for statistically significant sample sizes means that data collection can be an extremely lengthy process in AFM. The use of a single AFM instrument is known for its very low speed and not being suitable for scanning large areas, resulting in a very-low-throughput measurement. We address this challenge by parallelizing AFM instruments. The parallelization is achieved by miniaturizing the AFM instrument and operating many of them simultaneously. This instrument has the advantages that each miniaturized AFM can be operated independently and that the advances in the field of AFM, both in terms of speed and imaging modalities, can be implemented more easily. Moreover, a parallel AFM instrument also allows one to measure several physical parameters simultaneously; while one instrument measures nano-scale topography, another instrument can measure mechanical, electrical, or thermal properties, making it a lab-on-an-instrument. In this paper, a proof of principle of such a parallel AFM instrument has been demonstrated by analyzing the topography of large samples such as semiconductor wafers. This nanoinstrument provides new research opportunities in the nanometrology of wafers and nanolithography masks by enabling real die-to-die and wafer-level measurements and in cell biology by measuring the nano-scale properties of a large number of cells.

  2. An Adaptive Bandwidth Allocation for Energy Efficient Wireless Communication Systems

    Institute of Scientific and Technical Information of China (English)

    Yung-Fa Huang,Che-Hao Li; Chuan-Bi Lin; Chia-Chi Chang

    2015-01-01

    Abstract―In this paper, an energy efficient bandwidth allocation scheme is proposed for wireless communication systems. An optimal bandwidth expansion (OBE) scheme is proposed to assign the available system bandwidth for users. When the system bandwidth does not reach the full load, the remaining bandwidth can be energy-efficiently assigned to the other users. Simulation results show that the energy efficiency of the proposed OBE scheme outperforms the traditional same bandwidth expansion (SBE) scheme. Thus, the proposed OBE can effectively assign the system bandwidth and improve energy efficiency.

  3. Coherent temporal imaging with analog time-bandwidth compression

    CERN Document Server

    Asghari, Mohammad H

    2013-01-01

    We introduce the concept of coherent temporal imaging and its combination with the anamorphic stretch transform. The new system can measure both temporal profile of fast waveforms as well as their spectrum in real time and at high-throughput. We show that the combination of coherent detection and warped time-frequency mapping also performs time-bandwidth compression. By reducing the temporal width without sacrificing spectral resolution, it addresses the Big Data problem in real time instruments. The proposed method is the first application of the recently demonstrated Anamorphic Stretch Transform to temporal imaging. Using this method narrow spectral features beyond the spectrometer resolution can be captured. At the same time the output bandwidth and hence the record length is minimized. Coherent detection allows the temporal imaging and dispersive Fourier transform systems to operate in the traditional far field as well as in near field regimes.

  4. Compact silicon multimode waveguide spectrometer with enhanced bandwidth

    Science.gov (United States)

    Piels, Molly; Zibar, Darko

    2017-01-01

    Compact, broadband, and high-resolution spectrometers are appealing for sensing applications, but difficult to fabricate. Here we show using calibration data a spectrometer based on a multimode waveguide with 2 GHz resolution, 250 GHz bandwidth, and a 1.6 mm × 2.1 mm footprint. Typically, such spectrometers have a bandwidth limited by the number of modes supported by the waveguide. In this case, an on-chip mode-exciting element is used to repeatably excite distinct collections of waveguide modes. This increases the number of independent spectral channels from the number of modes to this number squared, resulting in an extension of the usable range. PMID:28290537

  5. Dynamic resource management using bandwidth brokers

    Institute of Scientific and Technical Information of China (English)

    Yu Chengzhi; Song Hantao; Hou Xianjun; Pan Chengsheng

    2006-01-01

    The admission control issue in the design of a centralized bandwidth broker model for dynamic control and management of QoS provisioning is studied. A two-phase differentiated flow treatment based dynamic admission control scheme under the centralized bandwidth broker model is proposed. In the proposed scheme, the flow requests are classified into two classes and get differentiated treatment according to their QoS demands. We demonstrate that this admission control scheme can not only improve the resource utilization but also guarantee the flows' QoS. Furthermore, the admission control is divided into two phases: edge admission control and interior admissio-n control. During the interior phase, the PoQ scheme is adopted, which enhances the call processing capability of the bandwidth broker. The simulation results show that the proposed scheme can result in lower flow blocking probability and higher resource utilization. And it also reduces the number of QoS state accesses/updates, thereby increasing the overall call processing capability of the bandwidth broker.

  6. A System Theoretic Approach to Bandwidth Estimation

    CERN Document Server

    Liebeherr, Jorg; Valaee, Shahrokh

    2008-01-01

    It is shown that bandwidth estimation in packet networks can be viewed in terms of min-plus linear system theory. The available bandwidth of a link or complete path is expressed in terms of a {\\em service curve}, which is a function that appears in the network calculus to express the service available to a traffic flow. The service curve is estimated based on measurements of a sequence of probing packets or passive measurements of a sample path of arrivals. It is shown that existing bandwidth estimation methods can be derived in the min-plus algebra of the network calculus, thus providing further mathematical justification for these methods. Principal difficulties of estimating available bandwidth from measurement of network probes are related to potential non-linearities of the underlying network. When networks are viewed as systems that operate either in a linear or in a non-linear regime, it is argued that probing schemes extract the most information at a point when the network crosses from a linear to a n...

  7. Adaptive bandwidth measurements of importance functions for speech intelligibility prediction.

    Science.gov (United States)

    Whitmal, Nathaniel A; DeRoy, Kristina

    2011-12-01

    The Articulation Index (AI) and Speech Intelligibility Index (SII) predict intelligibility scores from measurements of speech and hearing parameters. One component in the prediction is the "importance function," a weighting function that characterizes contributions of particular spectral regions of speech to speech intelligibility. Previous work with SII predictions for hearing-impaired subjects suggests that prediction accuracy might improve if importance functions for individual subjects were available. Unfortunately, previous importance function measurements have required extensive intelligibility testing with groups of subjects, using speech processed by various fixed-bandwidth low-pass and high-pass filters. A more efficient approach appropriate to individual subjects is desired. The purpose of this study was to evaluate the feasibility of measuring importance functions for individual subjects with adaptive-bandwidth filters. In two experiments, ten subjects with normal-hearing listened to vowel-consonant-vowel (VCV) nonsense words processed by low-pass and high-pass filters whose bandwidths were varied adaptively to produce specified performance levels in accordance with the transformed up-down rules of Levitt [(1971). J. Acoust. Soc. Am. 49, 467-477]. Local linear psychometric functions were fit to resulting data and used to generate an importance function for VCV words. Results indicate that the adaptive method is reliable and efficient, and produces importance function data consistent with that of the corresponding AI/SII importance function.

  8. Kernel bandwidth estimation for non-parametric density estimation: a comparative study

    CSIR Research Space (South Africa)

    Van der Walt, CM

    2013-12-01

    Full Text Available We investigate the performance of conventional bandwidth estimators for non-parametric kernel density estimation on a number of representative pattern-recognition tasks, to gain a better understanding of the behaviour of these estimators in high...

  9. Single phase forced convection cooling of high power leds

    NARCIS (Netherlands)

    Ozdemir, M.Z.; Chestakov, D.; Frijns, A.J.H.

    2011-01-01

    LEDs are strong candidates for future illumination applications dueto their much lower consumption of energy compared to conventional lighting options. One of key problems in development of LEDs is successful thermal management during illumination. Therefore, current research ongoing related to high

  10. Improved Radiation and Bandwidth of Triangular and Star Patch Antenna

    Directory of Open Access Journals (Sweden)

    M. Ramkumar Prabhu

    2012-06-01

    Full Text Available This study presents a hexagonal shape Defected Ground Structure (DGS implemented on two element triangular patch microstrip antenna array. The radiation performance of the antenna is characterized by varying the geometry and dimension of the DGS and also by locating the DGS at specific position which were simulated. Simulation and measurement results have verified that the antenna with DGS had improved the antenna without DGS. Measurement results of the hexagonal DGS have axial ratio bandwidth enhancement of 10 MHz, return loss improvement of 35%, mutual coupling reduction of 3 dB and gain enhancement of 1 dB. A new wideband and small size star shaped patch antenna fed capacitively by a small diamond shape patch is proposed. To enhance the impedance bandwidth, posts are incorporated under the patch antenna. HFSS high frequency simulator is employed to analyze the proposed antenna and simulated results on the return loss, the E- and H-plane radiation patterns and Gain of the proposed antenna are presented at various frequencies. The antenna is able to achieve in the range of 4-8.8 GHz an impedance bandwidth of 81% for return loss of less than-10 dB.

  11. Dispersion and optical gradient force from high-order mode coupling between two hyperbolic metamaterial waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guanghui, E-mail: gsnuwgh@163.com; Zhang, Weifeng; Lu, Jiahui; Zhao, Huijun

    2016-08-12

    We analytically study dispersion properties and optical gradient forces of different-order transverse magnetic (TM) modes in two coupled hyperbolic metamaterial waveguides (HMMWs). According to Maxwell's equations, we obtain the dispersion relation of symmetric and antisymmetric modes, and calculate optical gradient forces of different-order modes by using Maxwell stress tensor. Numerical results show that the dispersion properties are dependent on the filling ratio, and the optical gradient forces of high-order TM modes are larger than the fundamental mode when the gap between two HMMWs is very narrow, but they weaken much faster than the case of low-order TM modes with the gap width increasing. In addition, the effects of the dielectric surrounding of waveguides on the coupling effect and optical gradient force are clarified. These properties offer an avenue for various optomechanical applications in optical sensors and actuators. - Highlights: • The dependence of dispersion properties in hyperbolic metamaterials on the filling ratio is analyzed. • It is possible that the optical gradient forces of high-order modes are larger than the fundamental mode. • Optical gradient forces of high-order modes weaken much faster than the case of low-order modes. • The influence of the dielectric surrounding on the coupling effect and optical gradient force are clarified.

  12. Bandwidth-sharing in LHCONE, an analysis of the problem

    Science.gov (United States)

    Wildish, T.

    2015-12-01

    The LHC experiments have traditionally regarded the network as an unreliable resource, one which was expected to be a major source of errors and inefficiency at the time their original computing models were derived. Now, however, the network is seen as much more capable and reliable. Data are routinely transferred with high efficiency and low latency to wherever computing or storage resources are available to use or manage them. Although there was sufficient network bandwidth for the experiments’ needs during Run-1, they cannot rely on ever-increasing bandwidth as a solution to their data-transfer needs in the future. Sooner or later they need to consider the network as a finite resource that they interact with to manage their traffic, in much the same way as they manage their use of disk and CPU resources. There are several possible ways for the experiments to integrate management of the network in their software stacks, such as the use of virtual circuits with hard bandwidth guarantees or soft real-time flow-control, with somewhat less firm guarantees. Abstractly, these can all be considered as the users (the experiments, or groups of users within the experiment) expressing a request for a given bandwidth between two points for a given duration of time. The network fabric then grants some allocation to each user, dependent on the sum of all requests and the sum of available resources, and attempts to ensure the requirements are met (either deterministically or statistically). An unresolved question at this time is how to convert the users’ requests into an allocation. Simply put, how do we decide what fraction of a network's bandwidth to allocate to each user when the sum of requests exceeds the available bandwidth? The usual problems of any resourcescheduling system arise here, namely how to ensure the resource is used efficiently and fairly, while still satisfying the needs of the users. Simply fixing quotas on network paths for each user is likely to lead

  13. BACH:A Bandwidth-Aware Hybrid Cache Hierarchy Design with Nonvolatile Memories

    Institute of Scientific and Technical Information of China (English)

    Jishen Zhao; Cong Xu; Tao Zhang; Yuan Xie

    2016-01-01

    Limited main memory bandwidth is becoming a fundamental performance bottleneck in chip-multiprocessor (CMP) design. Yet directly increasing the peak memory bandwidth can incur high cost and power consump-tion. In this paper, we address this problem by proposing a memory, a bandwidth-aware reconfigurable cache hierarchy, BACH, with hybrid memory technologies. Components of our BACH design include a hybrid cache hierarchy, a reconfigura-tion mechanism, and a statistical prediction engine. Our hybrid cache hierarchy chooses different memory technologies with various bandwidth characteristics, such as spin-transfer torque memory (STT-MRAM), resistive memory (ReRAM), and embedded DRAM (eDRAM), to configure each level so that the peak bandwidth of the overall cache hierarchy is optimized. Our reconfiguration mechanism can dynamically adjust the cache capacity of each level based on the predicted bandwidth demands of running workloads. The bandwidth prediction is performed by our prediction engine. We evaluate the system performance gain obtained by BACH design with a set of multithreaded and multiprogrammed workloads with and without the limitation of system power budget. Compared with traditional SRAM-based cache design, BACH improves the system throughput by 58%and 14%with multithreaded and multiprogrammed workloads respectively.

  14. DBAS: A Deployable Bandwidth Aggregation System

    CERN Document Server

    Habak, Karim; Harras, Khaled A

    2012-01-01

    The explosive increase in data demand coupled with the rapid deployment of various wireless access technologies have led to the increase of number of multi-homed or multi-interface enabled devices. Fully exploiting these interfaces has motivated researchers to propose numerous solutions that aggregate their available bandwidths to increase overall throughput and satisfy the end-user's growing data demand. These solutions, however, have faced a steep deployment barrier that we attempt to overcome in this paper. We propose a Deployable Bandwidth Aggregation System (DBAS) for multi-interface enabled devices. Our system does not introduce any intermediate hardware, modify current operating systems, modify socket implementations, nor require changes to current applications or legacy servers. The DBAS architecture is designed to automatically estimate the characteristics of applications and dynamically schedule various connections or packets to different interfaces. Since our main focus is deployability, we fully i...

  15. Digital demodulator for wide bandwidth SAR

    DEFF Research Database (Denmark)

    Jørgensen, Jørn Hjelm

    2000-01-01

    A novel approach to the design of efficient digital quadrature demodulators for wide bandwidth SAR systems is described. Efficiency is obtained by setting the intermediate frequency to 1/4 the ADC sampling frequency. One channel is made filter-free by synchronizing the local oscillator...... with the output decimator. The filter required by the other channel is optimized through global search using the system level performance metrics integrated sidelobe level ratio (ISLR) and peak sidelobe level ratio (PSLR)....

  16. Prying Force Calculation and Design Method for T-shaped Tensile Connector with High Strength Bolt

    Institute of Scientific and Technical Information of China (English)

    Zhaoxin Hou; Guohong Huang; Chao Gong

    2015-01-01

    In order to establish the design method for T⁃shaped tensile connector with high strength bolt, the theoretical analysis is carried out. Firstly, it analyzes the performance of the connector and establishes prying force calculation model. Based on the model, prying force equation and function between bolt prying force and flange thickness is derived, and the min and max thickness requirement of flange plate under a certain tension load is then obtained. Finally, two simplified design methods of the connector are proposed, which are bolt pulling capacity method and flange plate bending capacity method.

  17. A Novel Dynamic Bandwidth Allocation Algorithm with Correction-based the Multiple Traffic Prediction in EPON

    Directory of Open Access Journals (Sweden)

    Ziyi Fu

    2012-10-01

    Full Text Available According to the upstream TDM in the system of Ethernet passive optical network (EPON, this paper proposes a novel dynamic bandwidth allocation algorithm which supports the mechanism with correction-based the multiple services estimation. To improve the real-time performance of the bandwidth allocation, this algorithm forecasts the traffic of high priority services, and then pre-allocate bandwidth for various priority services is corrected according to Gaussian distribution characteristics, which will make traffic prediction closer to the real traffic. The simulation results show that proposed algorithm is better than the existing DBA algorithm. Not only can it meet the delay requirement of high priority services, but also control the delay abnormity of low priority services. In addition, with rectification scheme, it obviously improves the bandwidth utilization.

  18. A wide bandwidth analog front-end circuit for 60-GHz wireless communication receiver

    Science.gov (United States)

    Furuta, M.; Okuni, H.; Hosoya, M.; Sai, A.; Matsuno, J.; Saigusa, S.; Itakura, T.

    2014-03-01

    This paper presents an analog front-end circuit for a 60-GHz wireless communication receiver. The feature of the proposed analog front-end circuit is a bandwidth more than 1-GHz wide. To expand the bandwidth of a low-pass filter and a voltage gain amplifier, a technique to reduce the parasitic capacitance of a transconductance amplifier is proposed. Since the bandwidth is also limited by on-resistance of the ADC sampling switch, a switch separation technique for reduction of the on-resistance is also proposed. In a high-speed ADC, the SNDR is limited by the sampling jitter. The developed high resolution VCO auto tuning effectively reduces the jitter of PLL. The prototype is fabricated in 65nm CMOS. The analog front-end circuit achieves over 1-GHz bandwidth and 27.2-dB SNDR with 224 mW Power consumption.

  19. Flange joint system for SRF cavities utilizing high force spring clamps for low particle generation

    Energy Technology Data Exchange (ETDEWEB)

    None

    2017-09-05

    A flange joint system for SRF cavities. The flange joint system includes a set of high force spring clamps that produce high force on the simple flanges of Superconducting Radio Frequency (SRF) cavities to squeeze conventional metallic seals. The system establishes the required vacuum and RF-tight seal with minimum particle contamination to the inside of the cavity assembly. The spring clamps are designed to stay within their elastic range while being forced open enough to mount over the flange pair. Upon release, the clamps have enough force to plastically deform metallic seal surfaces and continue to a new equilibrium sprung dimension where the flanges remain held against one another with enough preload such that normal handling will not break the seal.

  20. Gaussian entanglement distribution with GHz bandwidth

    CERN Document Server

    Ast, Stefan; Mehmet, Moritz; Schnabel, Roman

    2016-01-01

    The distribution of Gaussian entanglement can be used to generate a mathematically-proven secure key for quantum cryptography. The distributed secret key rate is limited by the bandwidth of the nonlinear resonators used for entanglement generation, which is less than 100 MHz for current state-of-the-art setups. The development of an entanglement source with a higher bandwidth promises an increased measurement speed and a linear boost in the secure data rate. Here, we present the experimental realization of a continuous-variable entanglement source with a bandwidth of more than 1.25 GHz. The measured entanglement spectrum was quantified via the inseparability criterion introduced by Duan and coworkers with a critical value of 4 below which entanglement is certified. The measurements yielded an inseparability value of about 1.8 at a frequency of 300 MHz to about 2.8 at 1.2 GHz extending further to about 3.1 at 1.48 GHz. In the experiment we used two 2.6 mm long monolithic PPKTP crystal resonators to generate tw...

  1. A Novel Bandwidth Efficient Transmit Diversity Scheme Based on Water-filling

    Institute of Scientific and Technical Information of China (English)

    SHENCong; DAILin; ZHOUShidong; YAOYan

    2004-01-01

    In this paper we propose a novel bandwidth efficient transmit diversity scheme based on layered space-time architecture, in which Channel state information (CSI) is fully utilized to maximize channel capacity according to water-filling principle. It is shown that compared with V-BLAST, this new scheme can maintain the same high bandwidth efficiency, but achieve much better performance thanks to more effective transmission power allocation and diversity gain.

  2. Transmission Bandwidth Tunability of a Liquid-Filled Photonic Bandgap Fiber

    Institute of Scientific and Technical Information of China (English)

    ZOU Bing; LIU Yan-Ge; DU Jiang-Sing; WANG Zhi; HAN Ting-Ting; XU Jian-Bo; LI Yuan; LIU Bo

    2009-01-01

    @@ A temperature tunable photonic bandgap tiber (PBGF) is demonstrated by an index-guiding photonic crystal fiber filled with high-index liquid. The temperature tunable characteristics of the fiber axe experimentally and numerically investigated. Compression of transmission bandwidth of the PBGF is demonstrated by changing the temperature of part of the fiber. The tunable transmission bandwidth with a range of 250 nm is achieved by changing the temperature from 30℃ to 90℃.

  3. A high performance sensor for triaxial cutting force measurement in turning.

    Science.gov (United States)

    Zhao, You; Zhao, Yulong; Liang, Songbo; Zhou, Guanwu

    2015-04-03

    This paper presents a high performance triaxial cutting force sensor with excellent accuracy, favorable natural frequency and acceptable cross-interference for high speed turning process. Octagonal ring is selected as sensitive element of the designed sensor, which is drawn inspiration from ring theory. A novel structure of two mutual-perpendicular octagonal rings is proposed and three Wheatstone full bridge circuits are specially organized in order to obtain triaxial cutting force components and restrain cross-interference. Firstly, the newly developed sensor is tested in static calibration; test results indicate that the sensor possesses outstanding accuracy in the range of 0.38%-0.83%. Secondly, impacting modal tests are conducted to identify the natural frequencies of the sensor in triaxial directions (i.e., 1147 Hz, 1122 Hz and 2035 Hz), which implies that the devised sensor can be used for cutting force measurement in a high speed lathe when the spindle speed does not exceed 17,205 rev/min in continuous cutting condition. Finally, an application of the sensor in turning process is operated to show its performance for real-time cutting force measurement; the measured cutting forces demonstrate a good accordance with the variation of cutting parameters. Thus, the developed sensor possesses perfect properties and it gains great potential for real-time cutting force measurement in turning.

  4. A High Performance Sensor for Triaxial Cutting Force Measurement in Turning

    Directory of Open Access Journals (Sweden)

    You Zhao

    2015-04-01

    Full Text Available This paper presents a high performance triaxial cutting force sensor with excellent accuracy, favorable natural frequency and acceptable cross-interference for high speed turning process. Octagonal ring is selected as sensitive element of the designed sensor, which is drawn inspiration from ring theory. A novel structure of two mutual-perpendicular octagonal rings is proposed and three Wheatstone full bridge circuits are specially organized in order to obtain triaxial cutting force components and restrain cross-interference. Firstly, the newly developed sensor is tested in static calibration; test results indicate that the sensor possesses outstanding accuracy in the range of 0.38%–0.83%. Secondly, impacting modal tests are conducted to identify the natural frequencies of the sensor in triaxial directions (i.e., 1147 Hz, 1122 Hz and 2035 Hz, which implies that the devised sensor can be used for cutting force measurement in a high speed lathe when the spindle speed does not exceed 17,205 rev/min in continuous cutting condition. Finally, an application of the sensor in turning process is operated to show its performance for real-time cutting force measurement; the measured cutting forces demonstrate a good accordance with the variation of cutting parameters. Thus, the developed sensor possesses perfect properties and it gains great potential for real-time cutting force measurement in turning.

  5. modeling the effect of bandwidth allocation on network performance

    African Journals Online (AJOL)

    a control algorithm that regulates the amount of bandwidth allocated to each ... planning, development and optimization of their networks. PROBLEM ... Network bandwidth design, simulation, and management ...... A Dictionary of Mechanical.

  6. Superhydrophobic gecko feet with high adhesive forces towards water and their bio-inspired materials

    Science.gov (United States)

    Liu, Kesong; Du, Jiexing; Wu, Juntao; Jiang, Lei

    2012-01-01

    Functional integration is an inherent characteristic for multiscale structures of biological materials. In this contribution, we first investigate the liquid-solid adhesive forces between water droplets and superhydrophobic gecko feet using a high-sensitivity micro-electromechanical balance system. It was found, in addition to the well-known solid-solid adhesion, the gecko foot, with a multiscale structure, possesses both superhydrophobic functionality and a high adhesive force towards water. The origin of the high adhesive forces of gecko feet to water could be attributed to the high density nanopillars that contact the water. Inspired by this, polyimide films with gecko-like multiscale structures were constructed by using anodic aluminum oxide templates, exhibiting superhydrophobicity and a strong adhesive force towards water. The static water contact angle is larger than 150° and the adhesive force to water is about 66 μN. The resultant gecko-inspired polyimide film can be used as a ``mechanical hand'' to snatch micro-liter liquids. We expect this work will provide the inspiration to reveal the mechanism of the high-adhesive superhydrophobic of geckos and extend the practical applications of polyimide materials.

  7. Bandwidth Scale for Frequency Spectrum of Sea Waves

    Institute of Scientific and Technical Information of China (English)

    王伟; 孙孚; 钱成春; 邓拥军

    2000-01-01

    It is well known that energy spectrum bandwidth should be able to reflect the degree of energy concentration. However, the commonly used bandwidth factors defined by Longuet-Higgins could not fit the concept satisfactorily. A new kind of spectrum bandwidth scale factor with a clear physical meaning is given in the present paper and a constant is obtained which reveals the intrinsic characteristics of sea waves. Thereby a universal relationship between significant wave height of sea waves and spectrum bandwidth is established.

  8. Stimulated Brillouin scattering gain bandwidth reduction and applications in microwave photonics and optical signal processing

    Science.gov (United States)

    Preussler, Stefan; Schneider, Thomas

    2016-03-01

    Stimulated Brillouin scattering (SBS) is one of the most dominant nonlinear effects in standard single-mode fibers and its unique spectral characteristics, especially the narrow bandwidth, enable many different applications. Most of the applications would benefit from a narrower bandwidth. Different methods for the bandwidth reduction of SBS in optical fibers are presented and discussed. A bandwidth reduction down to 17% of the natural gain can be achieved by the superposition of the gain with two losses or the utilization of a multistage system. Furthermore, applications in the field of microwave photonics and optical signal processing like high-resolution spectroscopy of communication signals, the storage of optical data packets as well as the processing of frequency combs including generation of millimeter waves and ideal sinc-shaped Nyquist pulses are presented.

  9. Dispersion and optical gradient force from high-order mode coupling between two hyperbolic metamaterial waveguides

    Science.gov (United States)

    Wang, Guanghui; Zhang, Weifeng; Lu, Jiahui; Zhao, Huijun

    2016-08-01

    We analytically study dispersion properties and optical gradient forces of different-order transverse magnetic (TM) modes in two coupled hyperbolic metamaterial waveguides (HMMWs). According to Maxwell's equations, we obtain the dispersion relation of symmetric and antisymmetric modes, and calculate optical gradient forces of different-order modes by using Maxwell stress tensor. Numerical results show that the dispersion properties are dependent on the filling ratio, and the optical gradient forces of high-order TM modes are larger than the fundamental mode when the gap between two HMMWs is very narrow, but they weaken much faster than the case of low-order TM modes with the gap width increasing. In addition, the effects of the dielectric surrounding of waveguides on the coupling effect and optical gradient force are clarified. These properties offer an avenue for various optomechanical applications in optical sensors and actuators.

  10. Impact-force sparse reconstruction from highly incomplete and inaccurate measurements

    Science.gov (United States)

    Qiao, Baijie; Zhang, Xingwu; Gao, Jiawei; Chen, Xuefeng

    2016-08-01

    The classical l2-norm-based regularization methods applied for force reconstruction inverse problem require that the number of measurements should not be less than the number of unknown sources. Taking into account the sparse nature of impact-force in time domain, we develop a general sparse methodology based on minimizing l1-norm for solving the highly underdetermined model of impact-force reconstruction. A monotonic two-step iterative shrinkage/thresholding (MTWIST) algorithm is proposed to find the sparse solution to such an underdetermined model from highly incomplete and inaccurate measurements, which can be problematic with Tikhonov regularization. MTWIST is highly efficient for large-scale ill-posed problems since it mainly involves matrix-vector multiplies without matrix factorization. In sparsity frame, the proposed sparse regularization method can not only determine the actual impact location from many candidate sources but also simultaneously reconstruct the time history of impact-force. Simulation and experiment including single-source and two-source impact-force reconstruction are conducted on a simply supported rectangular plate and a shell structure to illustrate the effectiveness and applicability of MTWIST, respectively. Both the locations and force time histories of the single-source and two-source cases are accurately reconstructed from a single accelerometer, where the high noise level is considered in simulation and the primary noise in experiment is supposed to be colored noise. Meanwhile, the consecutive impact-forces reconstruction in a large-scale (greater than 104) sparse frame illustrates that MTWIST has advantages of computational efficiency and identification accuracy over Tikhonov regularization.

  11. Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Jannis Lübbe

    2013-01-01

    Full Text Available The noise of the frequency-shift signal Δf in noncontact atomic force microscopy (NC-AFM consists of cantilever thermal noise, tip–surface-interaction noise and instrumental noise from the detection and signal processing systems. We investigate how the displacement-noise spectral density dz at the input of the frequency demodulator propagates to the frequency-shift-noise spectral density dΔf at the demodulator output in dependence of cantilever properties and settings of the signal processing electronics in the limit of a negligible tip–surface interaction and a measurement under ultrahigh-vacuum conditions. For a quantification of the noise figures, we calibrate the cantilever displacement signal and determine the transfer function of the signal-processing electronics. From the transfer function and the measured dz, we predict dΔf for specific filter settings, a given level of detection-system noise spectral density dzds and the cantilever-thermal-noise spectral density dzth. We find an excellent agreement between the calculated and measured values for dΔf. Furthermore, we demonstrate that thermal noise in dΔf, defining the ultimate limit in NC-AFM signal detection, can be kept low by a proper choice of the cantilever whereby its Q-factor should be given most attention. A system with a low-noise signal detection and a suitable cantilever, operated with appropriate filter and feedback-loop settings allows room temperature NC-AFM measurements at a low thermal-noise limit with a significant bandwidth.

  12. Experimental study of forced convection heat transfer during upward and downward flow of helium at high pressure and high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Francisco Valentin; Narbeh Artoun; Masahiro Kawaji; Donald M. McEligot

    2015-08-01

    Fundamental high pressure/high temperature forced convection experiments have been conducted in support of the development of a Very High Temperature Reactor (VHTR) with a prismatic core. The experiments utilize a high temperature/high pressure gas flow test facility constructed for forced convection and natural circulation experiments. The test section has a single 16.8 mm ID flow channel in a 2.7 m long, 108 mm OD graphite column with four 2.3kW electric heater rods placed symmetrically around the flow channel. This experimental study presents the role of buoyancy forces in enhancing or reducing convection heat transfer for helium at high pressures up to 70 bar and high temperatures up to 873 degrees K. Wall temperatures have been compared among 10 cases covering the inlet Re numbers ranging from 500 to 3,000. Downward flows display higher and lower wall temperatures in the upstream and downstream regions, respectively, than the upward flow cases due to the influence of buoyancy forces. In the entrance region, convection heat transfer is reduced due to buoyancy leading to higher wall temperatures, while in the downstream region, buoyancyinduced mixing causes higher convection heat transfer and lower wall temperatures. However, their influences are reduced as the Reynolds number increases. This experimental study is of specific interest to VHTR design and validation of safety analysis codes.

  13. Spin-torque diode with tunable sensitivity and bandwidth by out-of-plane magnetic field

    Science.gov (United States)

    Li, X.; Zheng, C.; Zhou, Y.; Kubota, H.; Yuasa, S.; Pong, Philip W. T.

    2016-06-01

    Spin-torque diodes based on nanosized magnetic tunnel junctions are novel microwave detectors with high sensitivity and wide frequency bandwidth. While previous reports mainly focus on improving the sensitivity, the approaches to extend the bandwidth are limited. This work experimentally demonstrates that through optimizing the orientation of the external magnetic field, wide bandwidth can be achieved while maintaining high sensitivity. The mechanism of the frequency- and sensitivity-tuning is investigated through analyzing the dependence of resonant frequency and DC voltage on the magnitude and the tilt angle of hard-plane magnetic field. The frequency dependence is qualitatively explicated by Kittel's ferromagnetic resonance model. The asymmetric resonant frequency at positive and negative magnetic field is verified by the numerical simulation considering the in-plane anisotropy. The DC voltage dependence is interpreted through evaluating the misalignment angle between the magnetization of the free layer and the reference layer. The tunability of the detector performance by the magnetic field angle is evaluated through characterizing the sensitivity and bandwidth under 3D magnetic field. The frequency bandwidth up to 9.8 GHz or maximum sensitivity up to 154 mV/mW (after impedance mismatch correction) can be achieved by tuning the angle of the applied magnetic field. The results show that the bandwidth and sensitivity can be controlled and adjusted through optimizing the orientation of the magnetic field for various applications and requirements.

  14. Varactor-tuned superconducting filter with constant absolute bandwidth at VHF-band

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bo [Department of Physics, Tsinghua University, Beijing 100084 (China); Cao, Bisong, E-mail: bscao@tsinghua.edu.cn [Department of Physics, Tsinghua University, Beijing 100084 (China); Guo, Xubo; Zhang, Xiaoping [Department of Physics, Tsinghua University, Beijing 100084 (China); Chen, Yidong [Superconductor Technology Co., Ltd, Beijing 100085 (China); Wei, Bin; Jiang, Linan [Department of Physics, Tsinghua University, Beijing 100084 (China)

    2015-09-15

    Highlights: • A four-pole superconducting tunable filter at VHF-band with constant absolute bandwidth is proposed. • The novel resonator consists of a spiral-in-spiral-out (SISO) microstrip line with one end shorted to ground and the other loaded with a varactor diode. • Both combline and interdigital constructions for coupling are introduced, and tuned to meet the constant bandwidth requirements. • The measurements show bandwidth variation is less than 1.3% while tuning from 247.28 to 266.58 MHz, and a high Q{sub u} of 1600–5500 is archived. - Abstract: A four-pole superconducting tunable filter at VHF-band with constant absolute bandwidth is proposed. The resonator consists of a spiral-in-spiral-out (SISO) resonator with one end shorted to ground and the other end loaded with a varactor diode. Both combline and interdigital constructions for coupling are introduced, and tuned to meet the constant bandwidth requirement. The fabricated device has a compact size, a tuning range of 7.3% from 247.28 to 266.58, a 3-dB bandwidth of 2.32 ± 0.03 MHz. The insertion loss ranges from 0.5 to 1.6 dB, yielding a high unloaded Q of 1600–5500. The simulated and measured results show an excellent agreement.

  15. High Precision Prediction of Rolling Force Based on Fuzzy and Nerve Method for Cold Tandem Mill

    Institute of Scientific and Technical Information of China (English)

    JIA Chun-yu; SHAN Xiu-ying; NIU Zhao-ping

    2008-01-01

    The rolling force model for cold tandem mill was put forward by using the Elman dynamic recursive network method, based on the actual measured data. Furthermore, a good assumption is put forward, which brings a full universe of discourse self-adjusting factor fuzzy control, closed-loop adjusting, based on error feedback and expertise into a rolling force prediction model, to modify prediction outputs and improve prediction precision and robustness. The simulated results indicate that the method is highly effective and the prediction precision is better than that of the traditional method. Predicted relative error is less than ±4%, so the prediction is high precise for the cold tandem mill.

  16. A review of Air Force high efficiency cascaded multiple bandgap solar cell research and development

    Science.gov (United States)

    Rahilly, W. P.

    1979-01-01

    At the time of their conception, the cell stack systems to be discussed represent the best semiconductor materials combinations to achieve Air Force program goals. These systems are investigated thoroughly and the most promising systems, from the standpoint of high efficiency, are taken for further development with large area emphasized (at least 4 sq cm). The emphasis in the Air Force cascaded cell program is placed on eventual nonconcentrator application. This use of the final cell design considerably relieves the low resistance requirements for the tunnel junction. In a high concentration application the voltage drop across the tunnel junction can be a very serious problem.

  17. Acoustic radiation force of high-order Bessel beam standing wave tweezers on a rigid sphere.

    Science.gov (United States)

    Mitri, F G

    2009-12-01

    Particle manipulation using the acoustic radiation force of Bessel beams is an active field of research. In a previous investigation, [F.G. Mitri, Acoustic radiation force on a sphere in standing and quasi-standing zero-order Bessel beam tweezers, Annals of Physics 323 (2008) 1604-1620] an expression for the radiation force of a zero-order Bessel beam standing wave experienced by a sphere was derived. The present work extends the analysis of the radiation force to the case of a high-order Bessel beam (HOBB) of positive order m having an angular dependence on the phase phi. The derivation for the general expression of the force is based on the formulation for the total acoustic scattering field of a HOBB by a sphere [F.G. Mitri, Acoustic scattering of a high-order Bessel beam by an elastic sphere, Annals of Physics 323 (2008) 2840-2850; F.G. Mitri, Equivalence of expressions for the acoustic scattering of a progressive high order Bessel beam by an elastic sphere, IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control 56 (2009) 1100-1103] to derive the general expression for the radiation force function YJm,st(ka,beta,m)Bessel beam standing wave incident upon a rigid sphere immersed in non-viscous water are computed. The rigid sphere calculations for YJm,st(ka,beta,m)Bessel beam standing wave (m=0). The proposed theory is of particular interest essentially due to its inherent value as a canonical problem in particle manipulation using the acoustic radiation force of a HOBB standing wave on a sphere. It may also serve as the benchmark for comparison to other solutions obtained by strictly numerical or asymptotic approaches.

  18. Design principles for high-pressure force fields: Aqueous TMAO solutions from ambient to kilobar pressures

    Science.gov (United States)

    Hölzl, Christoph; Kibies, Patrick; Imoto, Sho; Frach, Roland; Suladze, Saba; Winter, Roland; Marx, Dominik; Horinek, Dominik; Kast, Stefan M.

    2016-04-01

    Accurate force fields are one of the major pillars on which successful molecular dynamics simulations of complex biomolecular processes rest. They have been optimized for ambient conditions, whereas high-pressure simulations become increasingly important in pressure perturbation studies, using pressure as an independent thermodynamic variable. Here, we explore the design of non-polarizable force fields tailored to work well in the realm of kilobar pressures - while avoiding complete reparameterization. Our key is to first compute the pressure-induced electronic and structural response of a solute by combining an integral equation approach to include pressure effects on solvent structure with a quantum-chemical treatment of the solute within the embedded cluster reference interaction site model (EC-RISM) framework. Next, the solute's response to compression is taken into account by introducing pressure-dependence into selected parameters of a well-established force field. In our proof-of-principle study, the full machinery is applied to N,N,N-trimethylamine-N-oxide (TMAO) in water being a potent osmolyte that counteracts pressure denaturation. EC-RISM theory is shown to describe well the charge redistribution upon compression of TMAO(aq) to 10 kbar, which is then embodied in force field molecular dynamics by pressure-dependent partial charges. The performance of the high pressure force field is assessed by comparing to experimental and ab initio molecular dynamics data. Beyond its broad usefulness for designing non-polarizable force fields for extreme thermodynamic conditions, a good description of the pressure-response of solutions is highly recommended when constructing and validating polarizable force fields.

  19. A passive available bandwidth estimation methodology

    OpenAIRE

    Cabellos Aparicio, Alberto; Thompson, John; García, Francisco J.; Domingo Pascual, Jordi

    2009-01-01

    The Available Bandwidth (AB) of an end-to-end path is its remaining capacity and it is an important metric for several applications such as overlay routing and P2P networking. That is why many AB estimation tools have been published recently. Most of these tools use the Probe Rate Model, which requires sending packet trains at a rate matching the AB. Its main issue is that it congests the path under measurement. We present a different approach: a novel passive methodology to estimate the AB ...

  20. Confocal microscopy via multimode fibers: fluorescence bandwidth

    Science.gov (United States)

    Loterie, Damien; Psaltis, Demetri; Moser, Christophe

    2016-03-01

    We recently described a method for confocal reflection imaging through fibers, as a way to increase contrast when imaging unstained biological specimens. Using a transmission matrix, focused spots can be created at the distal end of a fiber. The backscattered field coming back from the sample can be filtered using optical correlation to obtain spatial selectivity in the detection. In this proceedings article, we briefly review the working principle of this method, and we discuss how the scheme could be adapted to confocal fluorescence imaging. In particular, we show simulations of the achievable detection bandwidth when using step-index multimode fibers as imaging devices.

  1. The RSC chromatin remodelling ATPase translocates DNA with high force and small step size.

    Science.gov (United States)

    Sirinakis, George; Clapier, Cedric R; Gao, Ying; Viswanathan, Ramya; Cairns, Bradley R; Zhang, Yongli

    2011-06-15

    ATP-dependent chromatin remodelling complexes use the energy of ATP hydrolysis to reposition and reconfigure nucleosomes. Despite their diverse functions, all remodellers share highly conserved ATPase domains, many shown to translocate DNA. Understanding remodelling requires biophysical knowledge of the DNA translocation process: how the ATPase moves DNA and generates force, and how translocation and force generation are coupled on nucleosomes. Here, we characterize the real-time activity of a minimal RSC translocase 'motor' on bare DNA, using high-resolution optical tweezers and a 'tethered' translocase system. We observe on dsDNA a processivity of ∼35 bp, a speed of ∼25 bp/s, and a step size of 2.0 (±0.4, s.e.m.) bp. Surprisingly, the motor is capable of moving against high force, up to 30 pN, making it one of the most force-resistant motors known. We also provide evidence for DNA 'buckling' at initiation. These observations reveal the ATPase as a powerful DNA translocating motor capable of disrupting DNA-histone interactions by mechanical force.

  2. Multimode laser cooling and ultra-high sensitivity force sensing with nanowires

    CERN Document Server

    Hosseini, Mahdi; Slatyer, Harri J; Buchler, Ben C; Lam, Ping Koy

    2015-01-01

    Photo-induced forces can be used to manipulate and cool the mechanical motion of oscillators. When the oscillator is used as a force sensor, such as in atomic force microscopy, active feedback is an enticing route to enhancing measurement performance. Here, we show broadband multimode cooling of $-23$ dB down to a temperature of $8 \\pm 1$~K in the stationary regime. Through the use of periodic quiescence feedback cooling, we show improved signal-to-noise ratios for the measurement of transient signals. We compare the performance of real feedback to numerical post-processing of data and show that both methods produce similar improvements to the signal-to-noise ratio of force measurements. We achieved a room temperature force measurement sensitivity of $< 2\\times10^{-16}$ N with integration time of less than $0.1$ ms. The high precision and fast force microscopy results presented will potentially benefit applications in biosensing, molecular metrology, subsurface imaging and accelerometry.

  3. Radiation forces on a three-level atom in the high-order Bessel beams

    Institute of Scientific and Technical Information of China (English)

    Wang Zheng-Ling; Yin Jian-Ping

    2008-01-01

    The general expressions of the average dissipative and dipole forces acting on a A-configuration three-level atom in an arbitrary light field are derived by means of the optical Bloch equations based on the atomic density matrix elements, and the general properties of the average dissipative and dipole forces on a three-level atom in the linearly-polarized high-order Bessel beams (HBBs) are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Meanwhile we find a saturation effect of the average dissipative force in the HBB, which comes from the saturation of the upper-level population. Our study shows that the general expressions of the average dissipative and dipole forces on the three-level atom will be simplified to those of the two-level atom under the approximation of large detuning. Finally, we study the axial and azimuthal Doppler cooling of atoms in 1D optical molasses composed of two counter-propagating HBBs and discuss the azimuthal influence of the HBB on the Doppler cooling limit. We also find that the Doppler limit of atoms in the molasses HBB is slightly below the conventional Doppler limit of hг/(2кB) due to the orbital angular momentum lh of the HBB.

  4. Radiation force on absorbing targets and power measurements of a high intensity focused ultrasound (HIFU) source

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on the analytic expressions for the radiated field of a circular concave piston given by Hasegawa et al.,an integral for calculation of the radiation force on a plane absorbing target in a spherically focused field is derived.A general relation between acoustic power P and normal radiation force Fn is obtained under the condition of kr 1.Numerical computation is carried out by using the symbolic computation program for practically focused sources and absorbing circular targets.The results show that,for a given source,there is a range of target positions where the radiation force is independent of the target’s position under the assumption that the contribution of the acoustic field behind the target to the radiation force can be neglected.The experiments are carried out and confirm that there is a range of target positions where the measured radiation force is basically independent of the target’s position even at high acoustic power (up to 700 W).It is believed that when the radiation force method is used to measure the acoustic power radiated from a focused source,the size of the target must be selected in such a way that no observable sound can be found in the region behind the target.

  5. Ferroelectric Domain Imaging Mechanism in High-Vacuum Scanning Force Microscopy

    Institute of Scientific and Technical Information of China (English)

    ZENG Hua-Rong; YU Han-Feng; CHU Rui-Qing; LI Guo-Rong; YIN Qing-Rui

    2005-01-01

    @@ High-vacuum scanning force microscopy of the domain structures in PMN-PT single crystals is investigated. It has been shown that under high vacuum conditions, the polarization charges are not effectively compensated for by intrinsic screening charges from the ferroelectrics. This result suggests that the electrostatic tip-sample interaction plays a great contribution to the domain imaging mechanism in PMN-PT ferroelectric single crystals under high vacuum conditions.

  6. Effect of various loads on the force-time characteristics of the hang high pull.

    Science.gov (United States)

    Suchomel, Timothy J; Beckham, George K; Wright, Glenn A

    2015-05-01

    The purpose of this study was to investigate the effect of various loads on the force-time characteristics associated with peak power during the hang high pull (HHP). Fourteen athletic men (age: 21.6 ± 1.3 years; height: 179.3 ± 5.6 cm; body mass: 81.5 ± 8.7 kg; 1 repetition maximum [1RM] hang power clean [HPC]: 104.9 ± 15.1 kg) performed sets of the HHP at 30, 45, 65, and 80% of their 1RM HPC. Peak force, peak velocity, peak power, force at peak power, and velocity at peak power were compared between loads. Statistical differences in peak force (p = 0.001), peak velocity (p < 0.001), peak power (p = 0.015), force at peak power (p < 0.001), and velocity at peak power (p < 0.001) existed, with the greatest values for each variable occurring at 80, 30, 45, 80, and 30% 1RM HPC, respectively. Effect sizes between loads indicated that larger differences in velocity at peak power existed as compared with those displayed by force at peak power. It seems that differences in velocity may contribute to a greater extent to differences in peak power production as compared with force during the HHP. Further investigation of both force and velocity at peak power during weightlifting variations is necessary to provide insight on the contributing factors of power production. Specific load ranges should be prescribed to optimally train the variables associated with power development during the HHP.

  7. Harnessing optical forces in integrated photonic circuits.

    Science.gov (United States)

    Li, Mo; Pernice, W H P; Xiong, C; Baehr-Jones, T; Hochberg, M; Tang, H X

    2008-11-27

    The force exerted by photons is of fundamental importance in light-matter interactions. For example, in free space, optical tweezers have been widely used to manipulate atoms and microscale dielectric particles. This optical force is expected to be greatly enhanced in integrated photonic circuits in which light is highly concentrated at the nanoscale. Harnessing the optical force on a semiconductor chip will allow solid state devices, such as electromechanical systems, to operate under new physical principles. Indeed, recent experiments have elucidated the radiation forces of light in high-finesse optical microcavities, but the large footprint of these devices ultimately prevents scaling down to nanoscale dimensions. Recent theoretical work has predicted that a transverse optical force can be generated and used directly for electromechanical actuation without the need for a high-finesse cavity. However, on-chip exploitation of this force has been a significant challenge, primarily owing to the lack of efficient nanoscale mechanical transducers in the photonics domain. Here we report the direct detection and exploitation of transverse optical forces in an integrated silicon photonic circuit through an embedded nanomechanical resonator. The nanomechanical device, a free-standing waveguide, is driven by the optical force and read out through evanescent coupling of the guided light to the dielectric substrate. This new optical force enables all-optical operation of nanomechanical systems on a CMOS (complementary metal-oxide-semiconductor)-compatible platform, with substantial bandwidth and design flexibility compared to conventional electrical-based schemes.

  8. Opposing Shear-Induced Forces Dominate Inertial Focusing in Curved Channels and High Reynolds Numbers

    CERN Document Server

    Keinan, Eliezer; Nahmias, Yaakov

    2015-01-01

    Inertial focusing is the migration of particles in fluid toward equilibrium, where current theory predicts that shear-induced and wall-induced lift forces are balanced. First reported in 1961, this Segre-Silberberg effect is particularly useful for microfluidic isolation of cells and particles. Interestingly, recent work demonstrated particle focusing at high Reynolds numbers that cannot be explained by current theory. In this work, we show that non-monotonous velocity profiles, such as those developed in curved channels, create peripheral velocity maxima around which opposing shear-induced forces dominate over wall effects. Similarly, entry effects amplified in high Reynolds flow produce an equivalent trapping mechanism in short, straight channels. This new focusing mechanism in the developing flow regime enables a 10-fold miniaturization of inertial focusing devices, while our model corrects long-standing misconceptions about the nature of mechanical forces governing inertial focusing in curved channels.

  9. Relative Contributions of Heating and Momentum Forcing to High-Latitude Lower Thermospheric Winds

    Science.gov (United States)

    Kwak, Y. S.; Richmond, A. D.

    2015-12-01

    At high latitudes the thermospheric dynamics are gov­erned by various heat and momentum sources. Recently several modeling studies have been attempt­ed to understand the physical process that control the high-latitude lower thermospheric dynamics. Kwak and Richmond [2007] and Kwak et al. [2007] studied the momentum forcing bal­ance that are mainly responsible for maintaining the high-latitude lower thermospheric wind system by using the National Center for Atmospheric Research Thermo­sphere Ionosphere Electrodynamics General Circulation Model (NCAR TIE-GCM). Kwak and Richmond [2014] analyzed the divergence and vorticity of the high-latitude neutral wind field in the lower thermosphere during the south­ern summertime. In this study, we extend previous works by Kwak and Rich­mond [2007, 2014] and Kwak et al. [2007], which helped to better understand the physical processes maintaining thermospheric dynamics at high latitudes, and here perform a "term analysis of the potential vorticity equation" for the high-latitude neu­tral wind field in the lower thermosphere, on the basis of numerical simulations using the NCAR TIE-GCM. These analyses can provide insight into the relative strength of the heating and the momentum forcing responsible for driving rotational winds at the high-latitude lower thermosphere. The heating is the net heat including the heat transfer by downward molecular and eddy heat conduction, the absorption of solar ultraviolet (UV) and extreme ultraviolet (EUV) ra­diation, auroral heating by particles, Joule dissipation of ionospheric currents, release of chemical energy by the atomic oxygen recombination, and radiative CO2, NO and O infrared emissions. The momentum forcing is associated with the viscous force and the frictional drag force from convecting ions.

  10. Experimental study and design on high dynamic GNSS receiver using adaptive optimal bandwidth for carrier tracking loop%高动态GNSS接收机载波跟踪环自适应最优带宽设计与试验

    Institute of Scientific and Technical Information of China (English)

    唐康华; 武成锋; 杜亮; 何晓峰

    2014-01-01

    对于大多数高动态接收机,通常采用2阶FLL辅助的3阶PLL环路结构,由于存在FLL环路,导致跟踪精度的下降。针对卫星接收机的动态性能和信号载波功率噪声密度比,在综合考虑接收机跟踪环路中的各种误差源(热噪声、晶振误差、动态牵引误差等)的基础上,采用自适应最优带宽技术,设计一种适用于高动态的3阶PLL载波跟踪环。采用基于GPS数字中频信号的数字仿真和GNSS信号源对所设计的自适应最优带宽进行了验证,验证结果表明:在加速度为30g、过程中存在加加速度为30g/s的高动态情况下,采用18 Hz 3阶PLL不能对信号进行跟踪,而采用所设计的自适应最优带宽的3阶PLL环可以对信号进行可靠的跟踪;同时,和固定带宽接收机比较,所设计载波跟踪环环路能够跟踪50g的高动态Compass卫星信号,而采用固定带宽接收机失锁,并且定位精度优于1 m(2σ),测速精度优于0.2 m/s(2σ)。%For most GNSS receiver designs in high dynamic application, a second-order FLL aided 3rd order PLL is usually adopted as carrier tracking loop. Based on GNSS receiver dynamics and carrier power-to-noise density, the structure of GNSS receiver 3rd order PLL tracking loop for high dynamic applications was designed by using the adaptive optimal bandwidth method and taking the tracking errors(such as thermal noise, oscillator phase noise, dynamic stress error) into account. According to the designed adaptive optimal bandwidth method of the 3rd order PLL tracking loop, the digital simulation and test based GNSS simulator were performed. Simulation results show that on the condition of 30g line-of-sight acceleration and 30g/s jerk high dynamics, the designed adaptive optimal bandwidth method can track GNSS signal well, but when using the 18 Hz fixed-bandwidth 3rd order PLL, carrier tracking lock will be lost. When using the GNSS simulator, test results show that

  11. Bandwidth Partitioning in Decentralized Wireless Networks

    CERN Document Server

    Jindal, Nihar; Weber, Steven

    2007-01-01

    This paper addresses the following question, which is of interest in the design of a multiuser decentralized network. Given a total system bandwidth of W Hz and a fixed data rate constraint of R bps for each transmission, how many frequency slots N of size W/N should the band be partitioned into in order to maximize the number of simultaneous links in the network? Dividing the available spectrum results in two competing effects. On the positive side, a larger N allows for more parallel, non-interfering communications to take place in the same area. On the negative side, a larger N increases the SINR requirement for each link because the same information rate must be achieved over less bandwidth, which in turn increases the area consumed by each transmission. Exploring this tradeoff and determining the optimum value of N in terms of the system parameters is the focus of the paper. Using stochastic geometry, the optimal SINR threshold - which directly corresponds to the optimal spectral efficiency - is derived ...

  12. Bandwidth sharing networks with multiscale traffic

    Directory of Open Access Journals (Sweden)

    Mathieu Feuillet

    2015-03-01

    Full Text Available In multi-class communication networks, traffic surges due to one class of users can significantly degrade the performance for other classes. During these transient periods, it is thus of crucial importance to implement priority mechanisms that conserve the quality of service experienced by the affected classes, while ensuring that the temporarily unstable class is not entirely neglected. In this paper, we examine the complex interaction occurring between several classes of traffic when classes obtain bandwidth proportionally to their incoming traffic. We characterize the evolution of the performance measures of the network from the moment the initial surge takes place until the system reaches its equilibrium. Using a time-space-transition-scaling, we show that the trajectories of the temporarily unstable class can be described by a differential equation, while those of the stable classes retain their stochastic nature. In particular, we show that the temporarily unstable class evolves at a time-scale which is much slower than that of the stable classes. Although the time-scales decouple, the dynamics of the temporarily unstable and the stable classes continue to influence one another. We further proceed to characterize the obtained differential equations for several simple network examples. In particular, the macroscopic asymptotic behavior of the unstable class allows us to gain important qualitative insights on how the bandwidth allocation affects performance. We illustrate these results on several toy examples and we finally build a penalization rule using these results for a network integrating streaming and surging elastic traffic.

  13. Highly eccentric inspirals into a Schwarzschild black hole using self-force calculations

    Science.gov (United States)

    Osburn, Thomas; Warburton, Niels; Evans, Charles

    2016-03-01

    Eccentric-orbit inspirals into a massive black hole are calculated using the gravitational self-force. Both extreme-mass-ratio inspirals (EMRIs) and intermediate-mass-ratio inspirals (IMRIs) are modeled. These calculations include all dissipative and conservative first-order-in-the-mass-ratio effects for inspirals into a Schwarzschild black hole. We compute systems with initial eccentricities as high as e = 0.8 and initial separations as large as 100 M. In the case of EMRIs, the calculations follow the decay through many thousands of orbits up to the onset of the plunge. Inspirals are computed using an osculating-orbits scheme that is driven by self-force data from a hybridized self-force code. A Lorenz gauge self-force code is combined with highly accurate flux data from a Regge-Wheeler-Zerilli code, allowing the hybrid self-force model to track orbital phase in the inspirals to within 0.1 radians or better. Extensions of the method to include other physical effects are considered.

  14. Bullet Retarding Forces in Ballistic Gelatin by Analysis of High Speed Video

    CERN Document Server

    Gaylord, Steven; Courtney, Michael; Courtney, Amy

    2013-01-01

    Though three distinct wounding mechanisms (permanent cavity, temporary cavity, and ballistic pressure wave) are described in the wound ballistics literature, they all have their physical origin in the retarding force between bullet and tissue as the bullet penetrates. If the bullet path is the same, larger retarding forces produce larger wounding effects and a greater probability of rapid incapacitation. By Newton's third law, the force of the bullet on the tissue is equal in magnitude and opposite in direction to the force of the tissue on the bullet. For bullets penetrating with constant mass, the retarding force on the bullet can be determined by frame by frame analysis of high speed video of the bullet penetrating a suitable tissue simulant such as calibrated 10% ballistic gelatin. Here the technique is demonstrated with 9mm NATO bullets, 32 cm long blocks of gelatin, and a high speed video camera operating at 20,000 frames per second. It is found that different 9mm NATO bullets have a wide variety of pot...

  15. Nanomagnets with high shape anisotropy and strong crystalline anisotropy: perspectives on magnetic force microscopy.

    Science.gov (United States)

    Campanella, H; Jaafar, M; Llobet, J; Esteve, J; Vázquez, M; Asenjo, A; del Real, R P; Plaza, J A

    2011-12-16

    We report on a new approach for magnetic imaging, highly sensitive even in the presence of external, strong magnetic fields. Based on FIB-assisted fabricated high-aspect-ratio rare-earth nanomagnets, we produce groundbreaking magnetic force tips with hard magnetic character where we combine a high aspect ratio (shape anisotropy) together with strong crystalline anisotropy (rare-earth-based alloys). Rare-earth hard nanomagnets are then FIB-integrated to silicon microcantilevers as highly sharpened tips for high-field magnetic imaging applications. Force resolution and domain reversing and recovery capabilities are at least one order of magnitude better than for conventional magnetic tips. This work opens new, pioneering research fields on the surface magnetization process of nanostructures based either on relatively hard magnetic materials-used in magnetic storage media-or on materials like superparamagnetic particles, ferro/antiferromagnetic structures or paramagnetic materials.

  16. Wide-bandwidth Tm-based amplifier for laser acceleration driver

    Science.gov (United States)

    Copeland, Drew A.; Vetrovec, John; Litt, Amardeep S.

    2016-03-01

    We report on an investigation of novel 2 μm thulium (Tm)-based laser accelerator driver (LAD) offering efficient generation of high-energy pulses with high-peak power at high pulse repetition rate (PRF), high efficiency, and with near-diffraction-limited beam quality (BQ). Laser acceleration of electrons by ultrashortpulse laser-generated plasmas offers accelerators of much reduced size and cost compared to conventional accelerators of the same energy, thus replacing the traditional mammoth-size and costly accelerator research facilities with room-size systems1. A LAD operating at 2 μm wavelength offers ponderomotive forces four times that of 1 μm wavelength and six times that of a traditional 0.8 μm wavelength LAD. In addition, the Tm bandwidth of nearly 400 nm offers > 15% tunability and generation of ultrashort pulses down to 20% wall-plug efficiency. This work presents a preliminary analysis of Tm-based LAD configurations.

  17. Measurement of Levitation Forces of High-"T[subscript c] Superconductors

    Science.gov (United States)

    Becker, M.; Koblischka, M. R.; Hartmann, U.

    2010-01-01

    We show the construction of a so-called levitation balance which is capable of measuring the levitation forces between a permanent magnet and a superconducting high-T[subscript c] thin film sample. The underlying theoretical basis is discussed in detail. The experiment is performed as an introductory physics experiment for school students as well…

  18. Measurement of Levitation Forces of High-"T[subscript c] Superconductors

    Science.gov (United States)

    Becker, M.; Koblischka, M. R.; Hartmann, U.

    2010-01-01

    We show the construction of a so-called levitation balance which is capable of measuring the levitation forces between a permanent magnet and a superconducting high-T[subscript c] thin film sample. The underlying theoretical basis is discussed in detail. The experiment is performed as an introductory physics experiment for school students as well…

  19. Monsoonal response to mid-holocene orbital forcing in a high resolution GCM

    NARCIS (Netherlands)

    Bosmans, J.H.C.; Drijfhout, S.S.; Tuenter, E.; Lourens, L.J.; Hilgen, F.J.; Weber, S.L.

    2012-01-01

    In this study, we use a sophisticated high-resolution atmosphere-ocean coupled climate model, EC-Earth, to investigate the effect of Mid-Holocene orbital forcing on summer monsoons on both hemispheres. During the Mid-Holocene (6 ka), there was more summer insolation on the Northern Hemisphere than

  20. Monsoonal response to mid-holocene orbital forcing in a high resolution GCM

    NARCIS (Netherlands)

    Bosmans, J.H.C.; Drijfhout, S.S.; Tuenter, E.; Lourens, L.J.; Hilgen, F.J.; Weber, S.L.

    2012-01-01

    In this study, we use a sophisticated high-resolution atmosphere-ocean coupled climate model, EC-Earth, to investigate the effect of Mid-Holocene orbital forcing on summer monsoons on both hemispheres. During the Mid-Holocene (6 ka), there was more summer insolation on the Northern Hemisphere than t

  1. Levitation force and magnetization in bulk and thin film high T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Riise, A.B

    1998-04-01

    The authors present high-resolution measurements of the repulsive vertical force and its associated stiffness between a Nd-B-Fe magnet and a YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} superconductor in cylindrical geometry. The results are compared with theoretical predictions. The calculations are based on a model in which the superconductor is assumed to be either a sintered granular material or consisting of grains embedded in a nonactive matrix so that only intragranular currents are important. The critical state model is applied to each grain individually and closed form expressions for both vertical force F{sub z} and stiffness are obtained in a configuration with cylindrical symmetry. The model explains all features of the experimental results in a consistent way. A good quantitative agreement has been obtained using only three adjustable parameters. Several central aspects of the phenomenon of magnetic levitation with high-T{sub c} superconductors are presented. High-resolution measurements are made of the repulsive vertical force and its associated stiffness as well as the horizontal stabilizing force and the stiffness governing lateral vibrations. The results obtained at 77 K using a granular YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} sample and Nd-Fe-B magnet in a rectangular levitation configuration are compared with theoretical predictions. The calculations, which are based on the critical state model with the assumption that it applies to the grins individually, give closed-form expressions for all the measured quantities. It is concluded that the present model explains all features of the observations in a consistent way. Using only three adjustable parameters a good agreement exists also at a quantitative level. Experimental studies and theoretical modelling of the levitation force on a permanent magnet placed above a superconducting thin film are offered. It is shown that measurements of the levitation force is a simple and precise method to determine the

  2. Improvement of force factor of magnetostrictive vibration power generator for high efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Kita, Shota, E-mail: happiest3.7@gmail.com; Ueno, Toshiyuki; Yamada, Sotoshi [Kanazawa University, Kakuma-machi, Kanazawa-city, Ishikawa 920-1164 (Japan)

    2015-05-07

    We develop high power magnetostrictive vibration power generator for battery-free wireless electronics. The generator is based on a cantilever of parallel beam structure consisting of coil-wound Galfenol and stainless plates with permanent magnet for bias. Oscillating force exerted on the tip bends the cantilever in vibration yields stress variation of Galfenol plate, which causes flux variation and generates voltage on coil due to the law of induction. This generator has advantages over conventional, such as piezoelectric or moving magnet types, in the point of high efficiency, highly robust, and low electrical impedance. Our concern is the improvement of energy conversion efficiency dependent on the dimension. Especially, force factor, the conversion ratio of the electromotive force (voltage) on the tip velocity in vibration, has an important role in energy conversion process. First, the theoretical value of the force factor is formulated and then the validity was verified by experiments, where we compare four types of prototype with parameters of the dimension using 7.0 × 1.5 × 50 mm beams of Galfenol with 1606-turn wound coil. In addition, the energy conversion efficiency of the prototypes depending on load resistance was measured. The most efficient prototype exhibits the maximum instantaneous power of 0.73 W and energy of 4.7 mJ at a free vibration of frequency of 202 Hz in the case of applied force is 25 N. Further, it was found that energy conversion efficiency depends not only on the force factor but also on the damping (mechanical loss) of the vibration.

  3. Bandwidth Extension of Telephone Speech Aided by Data Embedding

    Directory of Open Access Journals (Sweden)

    David Malah

    2007-01-01

    Full Text Available A system for bandwidth extension of telephone speech, aided by data embedding, is presented. The proposed system uses the transmitted analog narrowband speech signal as a carrier of the side information needed to carry out the bandwidth extension. The upper band of the wideband speech is reconstructed at the receiving end from two components: a synthetic wideband excitation signal, generated from the narrowband telephone speech and a wideband spectral envelope, parametrically represented and transmitted as embedded data in the telephone speech. We propose a novel data embedding scheme, in which the scalar Costa scheme is combined with an auditory masking model allowing high rate transparent embedding, while maintaining a low bit error rate. The signal is transformed to the frequency domain via the discrete Hartley transform (DHT and is partitioned into subbands. Data is embedded in an adaptively chosen subset of subbands by modifying the DHT coefficients. In our simulations, high quality wideband speech was obtained from speech transmitted over a telephone line (characterized by spectral magnitude distortion, dispersion, and noise, in which side information data is transparently embedded at the rate of 600 information bits/second and with a bit error rate of approximately 3⋅10−4. In a listening test, the reconstructed wideband speech was preferred (at different degrees over conventional telephone speech in 92.5% of the test utterances.

  4. Bandwidth Extension of Telephone Speech Aided by Data Embedding

    Directory of Open Access Journals (Sweden)

    Sagi Ariel

    2007-01-01

    Full Text Available A system for bandwidth extension of telephone speech, aided by data embedding, is presented. The proposed system uses the transmitted analog narrowband speech signal as a carrier of the side information needed to carry out the bandwidth extension. The upper band of the wideband speech is reconstructed at the receiving end from two components: a synthetic wideband excitation signal, generated from the narrowband telephone speech and a wideband spectral envelope, parametrically represented and transmitted as embedded data in the telephone speech. We propose a novel data embedding scheme, in which the scalar Costa scheme is combined with an auditory masking model allowing high rate transparent embedding, while maintaining a low bit error rate. The signal is transformed to the frequency domain via the discrete Hartley transform (DHT and is partitioned into subbands. Data is embedded in an adaptively chosen subset of subbands by modifying the DHT coefficients. In our simulations, high quality wideband speech was obtained from speech transmitted over a telephone line (characterized by spectral magnitude distortion, dispersion, and noise, in which side information data is transparently embedded at the rate of 600 information bits/second and with a bit error rate of approximately . In a listening test, the reconstructed wideband speech was preferred (at different degrees over conventional telephone speech in of the test utterances.

  5. Excitation Forces on Point Absorbers Exposed to High Order Non-linear Waves

    DEFF Research Database (Denmark)

    Viuff, Thomas Hansen; Andersen, Morten Thøtt; Kramer, Morten

    2013-01-01

    of proper methods to calculate design pressure distributions has led to structural failures such as buckling in the shells in wave energy prototypes. As a step towards understanding the complex loading from high order non-linear waves, this paper presents a practical approach to estimate wave excitation...... forces accounting for both non-linearity and diffraction effects. The method is validated by laboratory experiments using a hemispherical point absorber with a 6-axis force transducer, but the technique is believed to be applicable for most types of submerged or semi-submerged floating devices...

  6. Highly asymmetric interaction forces induced by acoustic waves in coupled plate structures

    CERN Document Server

    Fan, Xiying; Zhang, Shenwei; Ke, Manzhu; Liu, Zhengyou

    2015-01-01

    Mutual forces can be induced between coupled structures when illuminated by external acoustic waves. In this Letter, we propose a concept of asymmetric interaction between two coupled plate-like structures, which is generated by oppositely incident plane waves. Besides the striking contrast in magnitude, the mutual force induced by one of the incidences can be tuned extremely strong due to the resonant excitation of the flexural plate modes. The highly asymmetric interaction with enhanced strength in single side should be potentially useful, such as in designing ultrasound instruments and sensors.

  7. Prediction of forces and moments on finned bodies at high angle of attack in transonic flow

    Energy Technology Data Exchange (ETDEWEB)

    Oberkampf, W. L.

    1981-04-01

    This report describes a theoretical method for the prediction of fin forces and moments on bodies at high angle of attack in subsonic and transonic flow. The body is assumed to be a circular cylinder with cruciform fins (or wings) of arbitrary planform. The body can have an arbitrary roll (or bank) angle, and each fin can have individual control deflection. The method combines a body vortex flow model and lifting surface theory to predict the normal force distribution over each fin surface. Extensive comparisons are made between theory and experiment for various planform fins. A description of the use of the computer program that implements the method is given.

  8. Kink topology control by high-frequency external forces in nonlinear Klein-Gordon models

    Science.gov (United States)

    Alvarez-Nodarse, R.; Quintero, N. R.; Mertens, F. G.

    2014-10-01

    A method of averaging is applied to study the dynamics of a kink in the damped double sine-Gordon equation driven by both external (nonparametric) and parametric periodic forces at high frequencies. This theoretical approach leads to the study of a double sine-Gordon equation with an effective potential and an effective additive force. Direct numerical simulations show how the appearance of two connected π kinks and of an individual π kink can be controlled via the frequency. An anomalous negative mobility phenomenon is also predicted by theory and confirmed by simulations of the original equation.

  9. Kink topology control by high-frequency external forces in nonlinear Klein-Gordon models.

    Science.gov (United States)

    Alvarez-Nodarse, R; Quintero, N R; Mertens, F G

    2014-10-01

    A method of averaging is applied to study the dynamics of a kink in the damped double sine-Gordon equation driven by both external (nonparametric) and parametric periodic forces at high frequencies. This theoretical approach leads to the study of a double sine-Gordon equation with an effective potential and an effective additive force. Direct numerical simulations show how the appearance of two connected π kinks and of an individual π kink can be controlled via the frequency. An anomalous negative mobility phenomenon is also predicted by theory and confirmed by simulations of the original equation.

  10. Experimental Contribution to High-Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    DEFF Research Database (Denmark)

    Kjølhede, Klaus; Santos, Ilmar

    2007-01-01

    Parameter identification procedures and model validation are major steps toward intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... of the magnetic forces is conducted using different experimental tests: (i) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor (ii) by measuring the input current and bearing...... gap variations, monitoring the bearing input signals. Advantages and drawbacks of the different methodologies are critically discussed. The linearity ranges are experimentally determined and the characterization of magnetic forces with a high accuracy of

  11. Experimental Contribution to High Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    DEFF Research Database (Denmark)

    Kjølhede, Klaus; Santos, Ilmar

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... of the magnetic forces is conducted using different experimental tests: (a) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor, (b) by measuring the input current and bearing...... gap variations, monitoring the bearing input signals. Advantages and drawbacks of the different methodologies are critically discussed. The linearity ranges are experimentally determined and the characterization of magnetic forces with a high accuracy of less than 1% is achieved. (%error is normalized...

  12. Force measurement and design of a torquing high-pull headgear.

    Science.gov (United States)

    Tabash, J W; Sandrik, J L; Bowman, D; Lang, R L; Klapper, L

    1984-07-01

    The dynamic extraoral force analyzer (DEFA) was found to be capable of measuring linear deflection as a function of force created by a headgear. Ten standard nontorqued face-bows with a cervical and a high-pull direction were tested to determine the reliability of the DEFA. Statistical analysis showed the DEFA to be reliable and accurate in differentiating various directions and deflections of maxillary molars. Doubled-over distal ends of the inner bow with 0 degree of torque and a parietal direction of pull were used as controls. The same face-bows with 9 degrees of buccal root torque were tested on the DEFA. These face-bows were tested to determine whether transverse translation without buccal crown tipping of the maxillary first molar will occur. Statistical analysis showed that transverse translation occurred at a force of 200 to 347 gm.

  13. A new class of high force, low-voltage, compliant actuation system

    Energy Technology Data Exchange (ETDEWEB)

    RODGERS,M. STEVEN; KOTA,SRIDHAR; HETRICK,JOEL; LI,ZHE; JENSEN,BRIAN D.; KRYGOWSKI,THOMAS W.; MILLER,SAMUEL L.; BARNES,STEPHEN MATTHEW; BURG,MICHAEL STANLEY

    2000-04-10

    Although many actuators employing electrostatic comb drives have been demonstrated in a laboratory environment, widespread acceptance in mass produced microelectromechanical systems (MEMS) may be limited due to issues associated with low drive force, large real estate demands, high operating voltages, and reliability concerns due to stiction. On the other hand, comb drives require very low drive currents, offer predictable response, and are highly compatible with the fabrication technology. The expand the application space and facilitate the widespread deployment of self-actuated MEMS, a new class of advanced actuation systems has been developed that maintains the highly desirable aspects of existing components, while significantly diminishing the issues that could impede large scale acceptance. In this paper, the authors will present low-voltage electrostatic actuators that offer a dramatic increase in force over conventional comb drive designs. In addition, these actuators consume only a small fraction of the chip area previously used, yielding significant gains in power density. To increase the stroke length of these novel electrostatic actuators, the authors have developed highly efficient compliant stroke amplifiers. The coupling of compact, high-force actuators with fully compliant displacement multipliers sets a new paradigm for highly integrated microelectromechanical systems.

  14. Bandwidth Analysis of Smart Meter Network Infrastructure

    DEFF Research Database (Denmark)

    Balachandran, Kardi; Olsen, Rasmus Løvenstein; Pedersen, Jens Myrup

    2014-01-01

    Advanced Metering Infrastructure (AMI) is a net-work infrastructure in Smart Grid, which links the electricity customers to the utility company. This network enables smart services by making it possible for the utility company to get an overview of their customers power consumption and also control...... devices in their costumers household e.g. heat pumps. With these smart services, utility companies can do load balancing on the grid by shifting load using resources the customers have. The problem investigated in this paper is what bandwidth require-ments can be expected when implementing such network...... to utilize smart meters and which existing broadband network technologies can facilitate this smart meter service. Initially, scenarios for smart meter infrastructure are identified. The paper defines abstraction models which cover the AMI scenarios. When the scenario has been identified a general overview...

  15. Optimal filter bandwidth for pulse oximetry

    Science.gov (United States)

    Stuban, Norbert; Niwayama, Masatsugu

    2012-10-01

    Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

  16. Bandwidth Improvement of UWB Microstrip Antenna Using Finite Ground Plane

    Directory of Open Access Journals (Sweden)

    Priyanka Mishra

    2015-06-01

    Full Text Available Microstrip antennas play a vital role in communication system. It is required in high performance wireless applications. But due to its resonant nature microstrip antennas have some considerable drawbacks like narrowband performance. Extensive study has been carried out on microstrip patch antennas in the recent past, but it still have large scope for improvement in the near future. To overcome narrow bandwidth problem, number of methods and techniques have been suggested and investigated, keeping in mind that the basic advantages of microstrip antenna should not be altered such as low profile, light weight, low cost and simple printed circuit structure. The area of investigation includes modification in geometrical shape of the antenna, use of resonators, use of dipole, and many other parameters. This paper presents a comparison between conventional microstrip antenna and microstip antenna with finite ground plane at ultra wideband. HFSS simulation tool is used here for antenna simulation. For feeding purpose microstrip feed line is used (50Ω. Optimized result provides impedance bandwidth of 7.2GHz with VSWR<2, operating frequency range is from 6.5GHz to 13.7GHz. Proposed antenna is useful for many ultra wideband applications.

  17. The Wideband Slope of Interference Channels: The Infinite Bandwidth Case

    CERN Document Server

    Shen, Minqi

    2010-01-01

    It is well known that minimum received energy per bit in the interference channel is $-1.59dB$ as if there were no interference. Thus, the best way to mitigate interference is to operate the interference channel in the low power regime, that is in the limit of infinite bandwidth. However, when the bandwidth is large, but finite, minimum received energy per bit alone does not characterize performance. Verdu introduced the wideband slope $\\mathcal{S}_{0}$ to characterize the performance in this regime. We show that a wideband slope of ${\\mathcal{S}_{0}}/{\\mathcal{S}_{0,{no interference}}}=1/2$ is achievable. This result is similar to recent results on degrees of freedom in the high SNR regime, and we use a type of interference alignment using delays to obtain the result. We also show that in many cases the wideband slope is upper bounded by ${\\mathcal{S}_{0}}/{\\mathcal{S}_{0,{no interference}}}\\leq 1/2}$ for large number of users $K$.

  18. Improving microwave antenna gain and bandwidth with phase compensation metasurface

    Directory of Open Access Journals (Sweden)

    Ke Chen

    2015-06-01

    Full Text Available Metasurface, as a planar version of artificial metamaterial, provide an effective way to manipulate electromagnetic wave propagation. Here, we present a transparent metasurface for compensating the out-of-phase radiation from a microstrip patch antenna to improve its radiation gain and bandwidth. Based on the equivalence principle of Huygens’ surface, we propose metasurface composed of both inductive and capacitive resonant elements which could produce high transmission with variable phase characteristics. Such metasurface mounted on a patch antenna can transform the spherical-like phase profile generated from the patch into an in-phase planar one. A prototype antenna has been fabricated and validated the squeezed radiation pattern with suppressed sidelobes as well as enhanced impedance bandwidth due to strong near-field coupling. As operating at around 5.7 GHz, the proposed antenna may have potential application in wireless communication systems especially for point-to-point data transmission. It is believed that the design methodology could also be scaled to other frequency bands such as millimeter or terahertz wave.

  19. Improving microwave antenna gain and bandwidth with phase compensation metasurface

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ke; Yang, Zhongjie; Feng, Yijun, E-mail: yjfeng@nju.edu.cn; Zhu, Bo; Zhao, Junming; Jiang, Tian [Department of Electronic Engineering, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 (China)

    2015-06-15

    Metasurface, as a planar version of artificial metamaterial, provide an effective way to manipulate electromagnetic wave propagation. Here, we present a transparent metasurface for compensating the out-of-phase radiation from a microstrip patch antenna to improve its radiation gain and bandwidth. Based on the equivalence principle of Huygens’ surface, we propose metasurface composed of both inductive and capacitive resonant elements which could produce high transmission with variable phase characteristics. Such metasurface mounted on a patch antenna can transform the spherical-like phase profile generated from the patch into an in-phase planar one. A prototype antenna has been fabricated and validated the squeezed radiation pattern with suppressed sidelobes as well as enhanced impedance bandwidth due to strong near-field coupling. As operating at around 5.7 GHz, the proposed antenna may have potential application in wireless communication systems especially for point-to-point data transmission. It is believed that the design methodology could also be scaled to other frequency bands such as millimeter or terahertz wave.

  20. Improving microwave antenna gain and bandwidth with phase compensation metasurface

    Science.gov (United States)

    Chen, Ke; Yang, Zhongjie; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian

    2015-06-01

    Metasurface, as a planar version of artificial metamaterial, provide an effective way to manipulate electromagnetic wave propagation. Here, we present a transparent metasurface for compensating the out-of-phase radiation from a microstrip patch antenna to improve its radiation gain and bandwidth. Based on the equivalence principle of Huygens' surface, we propose metasurface composed of both inductive and capacitive resonant elements which could produce high transmission with variable phase characteristics. Such metasurface mounted on a patch antenna can transform the spherical-like phase profile generated from the patch into an in-phase planar one. A prototype antenna has been fabricated and validated the squeezed radiation pattern with suppressed sidelobes as well as enhanced impedance bandwidth due to strong near-field coupling. As operating at around 5.7 GHz, the proposed antenna may have potential application in wireless communication systems especially for point-to-point data transmission. It is believed that the design methodology could also be scaled to other frequency bands such as millimeter or terahertz wave.

  1. BECSI: Bandwidth Efficient Certificate Status Information Distribution Mechanism for VANETs

    Directory of Open Access Journals (Sweden)

    Carlos Gañán

    2013-01-01

    Full Text Available Certificate revocation is a challenging task, especiallyin mobile network environments such as vehicular ad Hoc networks (VANETs.According to the IEEE 1609.2 security standard for VANETs, public keyinfrastructure (PKI will provide this functionality by means of certificate revocation lists (CRLs.When a certificate authority (CAneeds to revoke a certificate, itglobally distributes CRLs.Transmitting these lists pose a problem as they require high update frequencies and a lot of bandwidth. In this article, we propose BECSI, aBandwidth Efficient Certificate Status Informationmechanism to efficiently distributecertificate status information (CSI in VANETs.By means of Merkle hash trees (MHT, BECSI allowsto retrieve authenticated CSI not onlyfrom the infrastructure but also from vehicles actingas mobile repositories.Since these MHTs are significantly smaller than the CRLs, BECSIreduces the load on the CSI repositories and improves the response time for the vehicles.Additionally, BECSI improves the freshness of the CSIby combining the use of delta-CRLs with MHTs.Thus, vehicles that have cached the most current CRLcan download delta-CRLs to have a complete list of revoked certificates.Once a vehicle has the whole list of revoked certificates, it can act as mobile repository.

  2. Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats

    Science.gov (United States)

    Li, Hao; Liu, Wenzhong; Zhang, Hao F.

    2015-10-01

    Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10 μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications.

  3. Percent voluntary inactivation and peak force predictions with the interpolated twitch technique in individuals with high ability of voluntary activation.

    Science.gov (United States)

    Herda, Trent J; Walter, Ashley A; Costa, Pablo B; Ryan, Eric D; Hoge, Katherine M; Stout, Jeffrey R; Cramer, Joel T

    2011-10-01

    The purpose of this study was to examine the sensitivity and peak force prediction capability of the interpolated twitch technique (ITT) performed during submaximal and maximal voluntary contractions (MVCs) in subjects with the ability to maximally activate their plantar flexors. Twelve subjects performed two MVCs and nine submaximal contractions with the ITT method to calculate percent voluntary inactivation (%VI). Additionally, two MVCs were performed without the ITT. Polynomial models (linear, quadratic and cubic) were applied to the 10-90% VI and 40-90% VI versus force relationships to predict force. Peak force from the ITT MVC was 6.7% less than peak force from the MVC without the ITT. Fifty-eight percent of the 10-90% VI versus force relationships were best fit with nonlinear models; however, all 40-90% VI versus force relationships were best fit with linear models. Regardless of the polynomial model or the contraction intensities used to predict force, all models underestimated the actual force from 22% to 28%. There was low sensitivity of the ITT method at high contraction intensities and the predicted force from polynomial models significantly underestimated the actual force. Caution is warranted when interpreting the % VI at high contraction intensities and predicted peak force from submaximal contractions.

  4. LIFT FORCE ON ROTATING SPHERE AT LOW REYNOLDS NUMBERS AND HIGH ROTATIONAL SPEEDS

    Institute of Scientific and Technical Information of China (English)

    由长福; 祁海鹰; 徐旭常

    2003-01-01

    The lift force on an isolated rotating sphere in a uniform flow was investigated by means of a three-dimensional numerical simulation for low Reynolds numbers (based on the sphere diameter) (Re < 68.4) and high dimensionless rotational speeds (Γ< 5). The Navier-Stokes equations in Cartesian coordinate system were solved using a finite volume formulation based on SIMPLE procedure. The accuracy of the numerical simulation was tested through a comparison with available theoretical, numerical and experimental results at low Reynolds numbers, and it was found that they were in close agreement under the above mentioned ranges of the Reynolds number and rotational speed. From a detailed computation of the flow field around a rotational sphere in extended ranges of the Reynolds number and rotational speed, the results show that, with increasing the rotational speed or decreasing the Reynolds number, the lift coefficient increases. An empirical equation more accurate than those obtained by previous studies was obtained to describe both effects of the rotational speed and Reynolds number on the lift force on a sphere. It was found in calculations that the drag coefficient is not significantly affected by the rotation of the sphere. The ratio of the lift force to the drag force, both of which act on a sphere in a uniform flow at the same time, was investigated. For a small spherical particle such as one of about 100μm in diameter, even if the rotational speed reaches about 106 revolutions per minute, the lift force can be neglected as compared with the drag force.

  5. HIGHLY QUALIFIED WORKING FORCE – KEY ELEMENT OF INNOVATIVE DEVELOPMENT MODEL

    Directory of Open Access Journals (Sweden)

    M. Avksientiev

    2014-12-01

    Full Text Available Highly qualified working force is a central element of intensive development model in modern society. The article surveys the experience of countries that managed to transform their economy to the innovative one. Ukrainian economy cannot stand aside processes that dominate the world economy trends, thus we are to use this experience to succeed in future. Today any government of the world is facing challenges that occur due to transformation of the economy into informational one. This type of economy causes its transformation form extensive to intensive one. The main reasons under that is limitation of nature resources, material factors of production. Thus this approach depends much on the quality of working force. Unfortunately in Ukraine there is a misbalance in specialist preparation. This puts additional pressure on the educational sphere also. In order to avoid this pressure we are to conduct reforms in education sphere. Nowadays, in the world views and concepts of governmental role in the social development are changing. This why, even at times of economic recession educational costs are not reduced under the new economical doctrine in the EU. Highly qualified specialists, while creating new products and services play role of engineers in XXI century. They are to lead their industries to world leading positions. From economic point of view, highly qualified specialists benefit society with higher income rates, taxation and thus, increasing the living standards in society. Thus, the majority if modern scientists prove the importance of highly trained working force for more effective economic development.

  6. Adaptable Bandwidth for Harmonic Step-Frequency Radar

    Directory of Open Access Journals (Sweden)

    Anthony F. Martone

    2015-01-01

    Full Text Available A spectrum sensing technique is described which is used to enhance the performance of harmonic step-frequency radar in the presence of harmful radio frequency (RF interference (RFI. This technique passively monitors the RF spectrum for subbands of high signal-to-interference-plus-noise ratio (SINR within a constrained bandwidth of interest. An optimal subband is selected for the harmonic radar that maximizes SINR and minimizes the range resolution cell size, two conflicting objectives. The approach is tested using an experimental setup that injects high power RFI into a harmonic step-frequency radar, which significantly degrades radar performance. It is shown that the proposed spectrum sensing technique significantly improves the SINR and the peak-to-average sidelobe power level of the harmonic radar at the sacrifice of range resolution.

  7. Frequency Bandwidth Optimization of Left-Handed Metamaterial

    Science.gov (United States)

    Chevalier, Christine T.; Wilson, Jeffrey D.

    2004-01-01

    Recently, left-handed metamaterials (LHM s) have been demonstrated with an effective negative index of refraction and with antiparallel group and phase velocities for microwave radiation over a narrow frequency bandwidth. In order to take advantage of these characteristics for practical applications, it will be beneficial to develop LHM s with increased frequency bandwidth response and lower losses. In this paper a commercial three-dimensional electromagnetic simulation code is used to explore the effects of geometry parameter variations on the frequency bandwidth of a LHM at microwave frequencies. Utilizing an optimizing routine in the code, a geometry was generated with a bandwidth more than twice as large as the original geometry.

  8. Effective Bandwidth Utilization in IEEE802.11 for VOIP

    CERN Document Server

    Bhanu, S Vijay; Balakrishnan, V

    2010-01-01

    Voice over Internet protocol (VoIP) is one of the most important applications for the IEEE 802.11 wireless local area networks (WLANs). For network planners who are deploying VoIP over WLANs, one of the important issues is the VoIP capacity. VoIP bandwidth consumption over a WAN is one of the most important factors to consider when building a VoIP infrastructure. Failure to account for VoIP bandwidth requirements will severely limit the reliability of a VoIP system and place a huge burden on the WAN infrastructure. Less bandwidth utilization is the key reasons for reduced number of channel accesses in VOIP. But in the QoS point of view the free bandwidth of atleast 1-5% will improve the voice quality. This proposal utilizes the maximum bandwidth by leaving 1-5% free bandwidth. A Bandwidth Data rate Moderation (BDM) algorithm has been proposed which correlates the data rate specified in IEEE802.11b with the free bandwidth. At each time BDM will calculate the bandwidth utilization before sending the packet to i...

  9. A fast high-order method to calculate wakefield forces in an electron beam

    CERN Document Server

    Qiang, Ji; Ryne, Robert D

    2012-01-01

    In this paper we report on a high-order fast method to numerically calculate wakefield forces in an electron beam given a wake function model. This method is based on a Newton-Cotes quadrature rule for integral approximation and an FFT method for discrete summation that results in an $O(Nlog(N))$ computational cost, where $N$ is the number of grid points. Using the Simpson quadrature rule with an accuracy of $O(h^4)$, where $h$ is the grid size, we present numerical calculation of the wakefields from a resonator wake function model and from a one-dimensional coherent synchrotron radiation (CSR) wake model. Besides the fast speed and high numerical accuracy, the calculation using the direct line density instead of the first derivative of the line density avoids numerical filtering of the electron density function for computing the CSR wakefield force.

  10. Influence of carrier dynamics on the modulation bandwidth of quantum-dot based nanocavity devices

    DEFF Research Database (Denmark)

    Lorke, Michael; Nielsen, Torben Roland; Mørk, Jesper

    2010-01-01

    We theoretically investigate the modulation response of quantum-dot based nanocavity light emitting devices. For high Purcell enhancement factors, our theory predicts the possibility of decreasing the modulation bandwidth with increasing scattering rate into the lasing quantum-dot state. This cou......We theoretically investigate the modulation response of quantum-dot based nanocavity light emitting devices. For high Purcell enhancement factors, our theory predicts the possibility of decreasing the modulation bandwidth with increasing scattering rate into the lasing quantum-dot state...

  11. Measuring the interaction force between a high temperature superconductor and a permanent magnet

    OpenAIRE

    Valenzuela, S. O.; Jorge, G. A.; Rodriguez, E.

    1999-01-01

    Repulsive and attractive forces are both possible between a superconducting sample and a permanent magnet, and they can give place to magnetic levitation or free-suspension phenomena, respectively. We show experiments to quantify this magnetic interaction which represents a promising field regarding to short-term technological applications of high temperature superconductors. The measuring technique employs an electronic balance and a rare-earth magnet that induces a magnetic moment in a melt...

  12. Power and Efficiency Optimized in Traveling-Wave Tubes Over a Broad Frequency Bandwidth

    Science.gov (United States)

    Wilson, Jeffrey D.

    2001-01-01

    A traveling-wave tube (TWT) is an electron beam device that is used to amplify electromagnetic communication waves at radio and microwave frequencies. TWT's are critical components in deep space probes, communication satellites, and high-power radar systems. Power conversion efficiency is of paramount importance for TWT's employed in deep space probes and communication satellites. A previous effort was very successful in increasing efficiency and power at a single frequency (ref. 1). Such an algorithm is sufficient for narrow bandwidth designs, but for optimal designs in applications that require high radiofrequency power over a wide bandwidth, such as high-density communications or high-resolution radar, the variation of the circuit response with respect to frequency must be considered. This work at the NASA Glenn Research Center is the first to develop techniques for optimizing TWT efficiency and output power over a broad frequency bandwidth (ref. 2). The techniques are based on simulated annealing, which has the advantage over conventional optimization techniques in that it enables the best possible solution to be obtained (ref. 3). Two new broadband simulated annealing algorithms were developed that optimize (1) minimum saturated power efficiency over a frequency bandwidth and (2) simultaneous bandwidth and minimum power efficiency over the frequency band with constant input power. The algorithms were incorporated into the NASA coupled-cavity TWT computer model (ref. 4) and used to design optimal phase velocity tapers using the 59- to 64-GHz Hughes 961HA coupled-cavity TWT as a baseline model. In comparison to the baseline design, the computational results of the first broad-band design algorithm show an improvement of 73.9 percent in minimum saturated efficiency (see the top graph). The second broadband design algorithm (see the bottom graph) improves minimum radiofrequency efficiency with constant input power drive by a factor of 2.7 at the high band edge (64

  13. High-throughput single-molecule force spectroscopy for membrane proteins

    Energy Technology Data Exchange (ETDEWEB)

    Bosshart, Patrick D; Casagrande, Fabio; Frederix, Patrick L T M; Engel, Andreas; Fotiadis, Dimitrios [M E Mueller Institute for Structural Biology, Biozentrum of the University of Basel, CH-4056 Basel (Switzerland); Ratera, Merce; Palacin, Manuel [Institute for Research in Biomedicine, Barcelona Science Park, Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona and Centro de Investigacion Biomedica en Red de Enfermedades Raras, E-08028 Barcelona (Spain); Bippes, Christian A; Mueller, Daniel J [BioTechnology Center, Technical University, Tatzberg 47, D-01307 Dresden (Germany)], E-mail: andreas.engel@unibas.ch, E-mail: dimitrios.fotiadis@mci.unibe.ch

    2008-09-24

    Atomic force microscopy-based single-molecule force spectroscopy (SMFS) is a powerful tool for studying the mechanical properties, intermolecular and intramolecular interactions, unfolding pathways, and energy landscapes of membrane proteins. One limiting factor for the large-scale applicability of SMFS on membrane proteins is its low efficiency in data acquisition. We have developed a semi-automated high-throughput SMFS (HT-SMFS) procedure for efficient data acquisition. In addition, we present a coarse filter to efficiently extract protein unfolding events from large data sets. The HT-SMFS procedure and the coarse filter were validated using the proton pump bacteriorhodopsin (BR) from Halobacterium salinarum and the L-arginine/agmatine antiporter AdiC from the bacterium Escherichia coli. To screen for molecular interactions between AdiC and its substrates, we recorded data sets in the absence and in the presence of L-arginine, D-arginine, and agmatine. Altogether {approx}400 000 force-distance curves were recorded. Application of coarse filtering to this wealth of data yielded six data sets with {approx}200 (AdiC) and {approx}400 (BR) force-distance spectra in each. Importantly, the raw data for most of these data sets were acquired in one to two days, opening new perspectives for HT-SMFS applications.

  14. The response of a high-speed train wheel to a harmonic wheel-rail force

    Science.gov (United States)

    Sheng, Xiaozhen; Liu, Yuxia; Zhou, Xin

    2016-09-01

    The maximum speed of China's high-speed trains currently is 300km/h and expected to increase to 350-400km/h. As a wheel travels along the rail at such a high speed, it is subject to a force rotating at the same speed along its periphery. This fast moving force contains not only the axle load component, but also many components of high frequencies generated from wheel-rail interactions. Rotation of the wheel also introduces centrifugal and gyroscopic effects. How the wheel responds is fundamental to many issues, including wheel-rail contact, traction, wear and noise. In this paper, by making use of its axial symmetry, a special finite element scheme is developed for responses of a train wheel subject to a vertical and harmonic wheel-rail force. This FE scheme only requires a 2D mesh over a cross-section containing the wheel axis but includes all the effects induced by wheel rotation. Nodal displacements, as a periodic function of the cross-section angle 6, can be decomposed, using Fourier series, into a number of components at different circumferential orders. The derived FE equation is solved for each circumferential order. The sum of responses at all circumferential orders gives the actual response of the wheel.

  15. Studies of bandwidth dependence of laser plasma instabilities driven by the Nike laser

    Science.gov (United States)

    Weaver, J.; Kehne, D.; Obenschain, S.; Serlin, V.; Schmitt, A. J.; Oh, J.; Lehmberg, R. H.; Brown, C. M.; Seely, J.; Feldman, U.

    2012-10-01

    Experiments at the Nike laser facility of the Naval Research Laboratory are exploring the influence of laser bandwidth on laser plasma instabilities (LPI) driven by a deep ultraviolet pump (248 nm) that incorporates beam smoothing by induced spatial incoherence (ISI). In early ISI studies with longer wavelength Nd:glass lasers (1054 nm and 527 nm),footnotetextObenschain, PRL 62(1989);Mostovych, PRL 62(1987);Peyser, Phys. Fluids B 3(1991). stimulated Raman scattering, stimulated Brillouin scattering, and the two plasmon decay instability were reduced when wide bandwidth ISI (δν/ν˜0.03-0.19%) pulses irradiated targets at moderate to high intensities (10^14-10^15 W/cm^2). The current studies will compare the emission signatures of LPI from planar CH targets during Nike operation at large bandwidth (δν˜1THz) to observations for narrower bandwidth operation (δν˜0.1-0.3THz). These studies will help clarify the relative importance of the short wavelength and wide bandwidth to the increased LPI intensity thresholds observed at Nike. New pulse shapes are being used to generate plasmas with larger electron density scale-lengths that are closer to conditions during pellet implosions for direct drive inertial confinement fusion.

  16. Memory bandwidth-scalable motion estimation for mobile video coding

    Science.gov (United States)

    Hsieh, Jui-Hung; Tai, Wei-Cheng; Chang, Tian-Sheuan

    2011-12-01

    The heavy memory access of motion estimation (ME) execution consumes significant power and could limit ME execution when the available memory bandwidth (BW) is reduced because of access congestion or changes in the dynamics of the power environment of modern mobile devices. In order to adapt to the changing BW while maintaining the rate-distortion (R-D) performance, this article proposes a novel data BW-scalable algorithm for ME with mobile multimedia chips. The available BW is modeled in a R-D sense and allocated to fit the dynamic contents. The simulation result shows 70% BW savings while keeping equivalent R-D performance compared with H.264 reference software for low-motion CIF-sized video. For high-motion sequences, the result shows our algorithm can better use the available BW to save an average bit rate of up to 13% with up to 0.1-dB PSNR increase for similar BW usage.

  17. Efficiently parallelized modeling of tightly focused, large bandwidth laser pulses

    CERN Document Server

    Dumont, Joey; Lefebvre, Catherine; Gagnon, Denis; MacLean, Steve

    2016-01-01

    The Stratton-Chu integral representation of electromagnetic fields is used to study the spatio-temporal properties of large bandwidth laser pulses focused by high numerical aperture mirrors. We review the formal aspects of the derivation of diffraction integrals from the Stratton-Chu representation and discuss the use of the Hadamard finite part in the derivation of the physical optics approximation. By analyzing the formulation we show that, for the specific case of a parabolic mirror, the integrands involved in the description of the reflected field near the focal spot do not possess the strong oscillations characteristic of diffraction integrals. Consequently, the integrals can be evaluated with simple and efficient quadrature methods rather than with specialized, more costly approaches. We report on the development of an efficiently parallelized algorithm that evaluates the Stratton-Chu diffraction integrals for incident fields of arbitrary temporal and spatial dependence. We use our method to show that t...

  18. Casimir force between $\\delta-\\delta^{\\prime}$ mirrors transparent at high frequencies

    CERN Document Server

    Braga, Alessandra N; Alves, Danilo T

    2016-01-01

    We investigate, in the context of a real massless scalar field in $1+1$ dimensions, models of partially reflecting mirrors simulated by Dirac $\\delta-\\delta^{\\prime}$ point interactions. In the literature, these models do not exhibit full transparency at high frequencies. In order to provide a more realistic feature for these models, we propose a modified $\\delta-\\delta^{\\prime}$ point interaction that enables to achieve full transparency in the limit of high frequencies. Taking this modified $\\delta-\\delta^{\\prime}$ model into account, we investigate the Casimir force, comparing our results with those found in the literature.

  19. High resolution miniature dilatometer based on an atomic force microscope piezocantilever

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.-H.; Graf, D.; Murphy, T. P.; Tozer, S. W. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States); Schmiedeshoff, G. M. [Department of Physics, Occidental College, Los Angeles, California 90041 (United States)

    2009-11-15

    Thermal expansion, or dilation, is closely related to the specific heat, and provides useful information regarding material properties. The accurate measurement of dilation in confined spaces coupled with other limiting experimental environments such as low temperatures and rapidly changing high magnetic fields requires a new sensitive millimeter size dilatometer that has little or no temperature and field dependence. We have designed an ultracompact dilatometer using an atomic force microscope piezoresistive cantilever as the sensing element and demonstrated its versatility by studying the charge density waves in alpha uranium to high magnetic fields (up to 31 T). The performance of this piezoresistive dilatometer was comparable to that of a titanium capacitive dilatometer.

  20. Radiation forces on a Rayleigh dielectric sphere produced by highly focused parabolic scaling Bessel beams.

    Science.gov (United States)

    Guo, Mengwen; Zhao, Daomu

    2017-02-20

    The radiation forces on a Rayleigh dielectric particle induced by a highly focused parabolic scaling Bessel beam (PSBB) are investigated. Numerical results show that the zero-order PSBB can be used to trap a high-index particle at the focus and near the focus by the first-order PSBB. For the low-index particle, it can be guided or confined in the dark core of the nonzero-order PSBB but cannot be stably trapped in this single-beam trap. Further, we analyze the condition of trapping stability. It is found that the lower limit in the particle radius for stable trapping is different for different orders.

  1. High-speed atomic force microscope based on an astigmatic detection system

    Energy Technology Data Exchange (ETDEWEB)

    Liao, H.-S.; Chen, Y.-H.; Hwu, E.-T.; Chang, C.-S.; Hwang, I.-S., E-mail: ishwang@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Ding, R.-F.; Huang, H.-F.; Wang, W.-M. [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Huang, K.-Y. [Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2014-10-15

    High-speed atomic force microscopy (HS-AFM) enables visualizing dynamic behaviors of biological molecules under physiological conditions at a temporal resolution of 1s or shorter. A small cantilever with a high resonance frequency is crucial in increasing the scan speed. However, detecting mechanical resonances of small cantilevers is technically challenging. In this study, we constructed an atomic force microscope using a digital versatile disc (DVD) pickup head to detect cantilever deflections. In addition, a flexure-guided scanner and a sinusoidal scan method were implemented. In this work, we imaged a grating sample in air by using a regular cantilever and a small cantilever with a resonance frequency of 5.5 MHz. Poor tracking was seen at the scan rate of 50 line/s when a cantilever for regular AFM imaging was used. Using a small cantilever at the scan rate of 100 line/s revealed no significant degradation in the topographic images. The results indicate that a smaller cantilever can achieve a higher scan rate and superior force sensitivity. This work shows the potential for using a DVD pickup head in future HS-AFM technology.

  2. Magnetic Signals of High-Temperature Superconductor Bulk During the Levitation Force Measurement Process

    Science.gov (United States)

    Huang, Huan; Zheng, Jun; Qian, Nan; Che, Tong; Zheng, Botian; Jin, Liwei; Deng, Zigang

    2017-05-01

    In order to study the commonly neglected magnetic field information in the course of levitation force measurement process in a superconducting maglev system, a multipoint magnetic field measurement platform was employed to acquire magnetic signals of a bulk high-Tc superconductor on both the top and the bottom surface. Working conditions including field cooling (FC) and zero field cooling were investigated for these vertical down and up motions above a permanent magnet guideway performed on a HTS maglev measurement system. We have discussed the magnetic flux variation process based on the Bean model. A magnetic hysteresis effect similar to the levitation force hysteresis loop of the bulk superconductor was displayed and analyzed in this paper. What is more valuable, there exists some available magnetic flux on the top surface of the bulk superconductor, and the proportion is as high as 62.42% in the FC condition, which provides an experimental hint to design the superconductor bulk and the applied field for practical use in a more efficient way. In particular, this work reveals real-time magnetic flux variation of the bulk superconductor in the levitation application, which is the other important information in contrast to the macroscopic levitation and guidance force investigations in previous studies, and it enriches the existing research methods. The results are significant for understanding the magnetic characteristic of superconductors, and they can contribute to optimize the present HTS maglev system design.

  3. Magnetic Signals of High-Temperature Superconductor Bulk During the Levitation Force Measurement Process

    Science.gov (United States)

    Huang, Huan; Zheng, Jun; Qian, Nan; Che, Tong; Zheng, Botian; Jin, Liwei; Deng, Zigang

    2017-02-01

    In order to study the commonly neglected magnetic field information in the course of levitation force measurement process in a superconducting maglev system, a multipoint magnetic field measurement platform was employed to acquire magnetic signals of a bulk high-Tc superconductor on both the top and the bottom surface. Working conditions including field cooling (FC) and zero field cooling were investigated for these vertical down and up motions above a permanent magnet guideway performed on a HTS maglev measurement system. We have discussed the magnetic flux variation process based on the Bean model. A magnetic hysteresis effect similar to the levitation force hysteresis loop of the bulk superconductor was displayed and analyzed in this paper. What is more valuable, there exists some available magnetic flux on the top surface of the bulk superconductor, and the proportion is as high as 62.42% in the FC condition, which provides an experimental hint to design the superconductor bulk and the applied field for practical use in a more efficient way. In particular, this work reveals real-time magnetic flux variation of the bulk superconductor in the levitation application, which is the other important information in contrast to the macroscopic levitation and guidance force investigations in previous studies, and it enriches the existing research methods. The results are significant for understanding the magnetic characteristic of superconductors, and they can contribute to optimize the present HTS maglev system design.

  4. Experimental and numerical investigation of nanoparticle releasing in AFM nanomanipulation using high voltage electrostatic forces

    Science.gov (United States)

    Ghattan Kashani, H.; Shokrolahi, S.; Akbari Moayyer, H.; Shariat Panahi, M.; Shahmoradi Zavareh, A.

    2017-07-01

    Atomic Force Microscopes (AFMs) have been widely used as nanomanipulators due to their versatility to work with a broad range of materials and their controllable interaction force, among other features. While AFMs can effectively grasp, move, and position nanoscale objects in 2D environments through basic pull/push operations, they often lack the high precision required in many 3D pick and place applications, especially in non-vacuum environments. In this study, a novel method to resolve the adhesion problem between nanoscale objects and the AFM tip has been developed and tested. The method is based on the application of a high electrostatic voltage to the tip to produce the repulsive force required for the release of the nanoobject. The method is proposed for conductive nanoparticles and tips used in many nanomanipulation applications, and can be easily implemented on typical AFMs with minimal alterations. The applicability of the proposed method is investigated through a series of combined Molecular Dynamics/Finite Element simulations.

  5. High-resolution dynamic atomic force microscopy in liquids with different feedback architectures

    Directory of Open Access Journals (Sweden)

    John Melcher

    2013-02-01

    Full Text Available The recent achievement of atomic resolution with dynamic atomic force microscopy (dAFM [Fukuma et al., Appl. Phys. Lett. 2005, 87, 034101], where quality factors of the oscillating probe are inherently low, challenges some accepted beliefs concerning sensitivity and resolution in dAFM imaging modes. Through analysis and experiment we study the performance metrics for high-resolution imaging with dAFM in liquid media with amplitude modulation (AM, frequency modulation (FM and drive-amplitude modulation (DAM imaging modes. We find that while the quality factors of dAFM probes may deviate by several orders of magnitude between vacuum and liquid media, their sensitivity to tip–sample forces can be remarkable similar. Furthermore, the reduction in noncontact forces and quality factors in liquids diminishes the role of feedback control in achieving high-resolution images. The theoretical findings are supported by atomic-resolution images of mica in water acquired with AM, FM and DAM under similar operating conditions.

  6. Forced and natural gradient tracer tests in a highly heterogeneous porous aquifer: instrumentation and measurements

    Science.gov (United States)

    Ptak, T.; Teutsch, G.

    1994-07-01

    At the Horkheimer Insel experimental field site, several short to intermediate distance forced and natural gradient tracer tests with depth-integrated and multilevel sampling were conducted to characterize the aquifer transport properties. Compared with other test sites, the aquifer at the Horkheimer Insel is highly heterogeneous and highly conductive. Hence, new tracer measurement techniques had to be developed. This paper presents some of the instrumentation developed together with measurements and their initial interpretation. The results demonstrate that for contaminant transport predictions in highly heterogeneous and highly conductive aquifers, investigation techniques with a high resolution in time and space are needed. The aquifer heterogeneity is evident from the spatial variability of peak concentration, transport velocity and longitudinal macrodispersivity values obtained from the tracer tests. Furthermore, the tracer test results indicate that at the observation scale investigated, a complex numerical flow and transport model is needed to describe adequately mass transport within the heterogeneous aquifer.

  7. High sensitivity piezomagnetic force microscopy for quantitative probing of magnetic materials at the nanoscale.

    Science.gov (United States)

    Chen, Qian Nataly; Ma, Feiyue; Xie, Shuhong; Liu, Yuanming; Proksch, Roger; Li, Jiangyu

    2013-07-01

    Accurate scanning probing of magnetic materials at the nanoscale is essential for developing and characterizing magnetic nanostructures, yet quantitative analysis is difficult using the state of the art magnetic force microscopy, and has limited spatial resolution and sensitivity. In this communication, we develop a novel piezomagnetic force microscopy (PmFM) technique, with the imaging principle based on the detection of magnetostrictive response excited by an external magnetic field. In combination with the dual AC resonance tracking (DART) technique, the contact stiffness and energy dissipation of the samples can be simultaneously mapped along with the PmFM phase and amplitude, enabling quantitative probing of magnetic materials and structures at the nanoscale with high sensitivity and spatial resolution. PmFM has been applied to probe magnetic soft discs and cobalt ferrite thin films, demonstrating it as a powerful tool for a wide range of magnetic materials.

  8. Schlieren High Speed Imaging on Fluid Flow in Liquid Induced by Plasma-driven Interfacial Forces

    Science.gov (United States)

    Lai, Janis; Foster, John

    2016-10-01

    Effective plasma-based water purification depends heavily on the transport of plasma-derived reactive species from the plasma into the liquid. Plasma interactions at the liquid-gas boundary are known to drive circulation in the bulk liquid. This forced circulation is not well understood. A 2-D plasma- in-liquid water apparatus is currently being investigated as a means to study the plasma-liquid interface to understand not only reactive species flows but to also understand plasma- driven fluid dynamic effects in the bulk fluid. Using Schlieren high speed imaging, plasma-induced density gradients near the interfacial region and into the bulk solution are measured to investigate the nature of these interfacial forces. Plasma-induced flow was also measured using particle imaging velocimetry. NSF CBET 1336375 and DOE DE-SC0001939.

  9. Analysis of Electromagnetics Forces on Magnetically Suspended High-Speed Trains

    Directory of Open Access Journals (Sweden)

    Daniel Mayer

    2004-01-01

    Full Text Available High-speed superexpresses (HSST developed by Japanese airlines (JAL are based on the electrodynamics principle of magnetic suspension. The track contains short-circuited coils and interaction between them and superconductive coils in the vehicle produces its suspension. The paper includes a mathematical model for traction electrodynamics suspension device HSST represented by a system of linear differential equations with coefficients varying in time. Numerical analysis of this model fields the velocity-dependent lift and drag forces acting on the system. The time distribution of the lift force exhibits certain oscillations that may be suppressed by suitable placement of several superconductive levitation wings in the vehicle. The results obtained are in a good agreement with the knowledge found by various authors on prototype vehicles.

  10. Tip radius preservation for high resolution imaging in amplitude modulation atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Jorge R., E-mail: jorge.rr@cea.cu [Instituto de Ciencia de Materiales de Madrid, Sor Juana Inés de la Cruz 3, Canto Blanco, 28049 Madrid, España (Spain)

    2014-07-28

    The acquisition of high resolution images in atomic force microscopy (AFM) is correlated to the cantilever's tip shape, size, and imaging conditions. In this work, relative tip wear is quantified based on the evolution of a direct experimental observable in amplitude modulation atomic force microscopy, i.e., the critical amplitude. We further show that the scanning parameters required to guarantee a maximum compressive stress that is lower than the yield/fracture stress of the tip can be estimated via experimental observables. In both counts, the optimized parameters to acquire AFM images while preserving the tip are discussed. The results are validated experimentally by employing IgG antibodies as a model system.

  11. Measuring the interaction force between a high temperature superconductor and a permanent magnet

    Science.gov (United States)

    Valenzuela, S. O.; Jorge, G. A.; Rodríguez, E.

    1999-11-01

    Repulsive and attractive forces are both possible between a superconducting sample and a permanent magnet, and they can give rise to magnetic levitation or free-suspension phenomena, respectively. We show experiments to quantify this magnetic interaction, which represents a promising field with regard to short-term technological applications of high temperature superconductors. The measuring technique employs an electronic balance and a rare-earth magnet that induces a magnetic moment in a melt-textured YBa2Cu3O7 superconductor immersed in liquid nitrogen. The simple design of the experiments allows a fast and easy implementation in the advanced physics laboratory with a minimum cost. Actual levitation and suspension demonstrations can be done simultaneously as a help to interpret magnetic force measurements.

  12. Optimal Bandwidth Selection in Observed-Score Kernel Equating

    Science.gov (United States)

    Häggström, Jenny; Wiberg, Marie

    2014-01-01

    The selection of bandwidth in kernel equating is important because it has a direct impact on the equated test scores. The aim of this article is to examine the use of double smoothing when selecting bandwidths in kernel equating and to compare double smoothing with the commonly used penalty method. This comparison was made using both an equivalent…

  13. 47 CFR 78.104 - Authorized bandwidth and emission designator.

    Science.gov (United States)

    2010-10-01

    ... SERVICES CABLE TELEVISION RELAY SERVICE Technical Regulations § 78.104 Authorized bandwidth and emission... within the frequency limits of the assigned channel. (c) The emission designator shall be specified in... 47 Telecommunication 4 2010-10-01 2010-10-01 false Authorized bandwidth and emission...

  14. Avoiding bandwidth collapse in long chains of coupled optical microresonators.

    Science.gov (United States)

    Mookherjea, Shayan; Schneider, Mark A

    2011-12-01

    Coupled photonic oscillators and resonators are sensitive to unavoidable nanoscale disorder, and localization in periodic structures induced by disorder leads eventually to a complete collapse of the bandwidth, which is generally considered problematic for device applications. Here, we investigate the dependence of bandwidth collapse on the interresonator coupling coefficient, a parameter controllable by lithography or device operation.

  15. E-Readiness Assessment Model for Low Bandwidth Environment

    Directory of Open Access Journals (Sweden)

    Nazir Ahmad Suhail

    Full Text Available This paper reports on assessment of an e-readiness model for low bandwidth environment. The main focus of the model is on technological (bandwidth related critical factors that are barrier to the adoption of technology mediated learning in developing cou ...

  16. Development of nanomanipulator using a high-speed atomic force microscope coupled with a haptic device

    Energy Technology Data Exchange (ETDEWEB)

    Iwata, F., E-mail: tmfiwat@ipc.shizuoka.ac.jp [Faculty of Engineering, Shizuoka University, Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Johoku, Naka-ku, Hamamatsu 432-8011 (Japan); Ohashi, Y.; Ishisaki, I. [Faculty of Engineering, Shizuoka University, Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Picco, L.M. [H Will Physics Laboratory and IRC in Nanotechnology, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Ushiki, T. [Graduate School of Medical and Dental Sciences, Niigata University, Asahimachidori, Niigata, 951-8122 (Japan)

    2013-10-15

    The atomic force microscope (AFM) has been widely used for surface fabrication and manipulation. However, nanomanipulation using a conventional AFM is inefficient because of the sequential nature of the scan-manipulation scan cycle, which makes it difficult for the operator to observe the region of interest and perform the manipulation simultaneously. In this paper, a nanomanipulation technique using a high-speed atomic force microscope (HS-AFM) is described. During manipulation using the AFM probe, the operation is periodically interrupted for a fraction of a second for high-speed imaging that allows the topographical image of the manipulated surface to be periodically updated. With the use of high-speed imaging, the interrupting time for imaging can be greatly reduced, and as a result, the operator almost does not notice the blink time of the interruption for imaging during the manipulation. This creates a more intuitive interface with greater feedback and finesse to the operator. Nanofabrication under real-time monitoring was performed to demonstrate the utility of this arrangement for real-time nanomanipulation of sample surfaces under ambient conditions. Furthermore, the HS-AFM is coupled with a haptic device for the human interface, enabling the operator to move the HS-AFM probe to any position on the surface while feeling the response from the surface during the manipulation. - Highlights: • A nanomanipulater based on a high-speed atomic force microscope was developped. • High-speed imaging provides a valuable feedback during the manipulation operation. • Operator can feel the response from the surface via a haptic device during manipulation. • Nanofabrications under real-time monitoring were successfully performed.

  17. Global path and bandwidth scheduling in inter-data-center IP/optical transport network

    Science.gov (United States)

    Zhao, Yang; Wang, Lei; Chen, Xue; Yang, Futao; Shi, Sheping; Wang, Huitao

    2016-07-01

    We propose a flow-oriented global path and bandwidth scheduling scheme for inter-data-center IP/optical network. To improve the throughput of network and reduce the mutual impact between flows, we allow each flow to be carried by a multi-path optical channel data unit (ODU) channel. In addition bandwidth is allocated to flows fairly according to weight. Simulation results reveal that compared to high-priority-first mechanism, the method proposed improves average bandwidth allocation ratio by about 15% and allocation fairness between flows by 30%. Furthermore, compared to pure IP network, router ports are significantly saved and network cost can be reduced by up to 40% with scheme proposed in unified controlled IP/optical network.

  18. Optimization of Single-Sensor Two-State Hot-Wire Anemometer Transmission Bandwidth.

    Science.gov (United States)

    Ligęza, Paweł

    2008-10-28

    Hot-wire anemometric measurements of non-isothermal flows require the use of thermal compensation or correction circuitry. One possible solution is a two-state hot-wire anemometer that uses the cyclically changing heating level of a single sensor. The area in which flow velocity and fluid temperature can be measured is limited by the dimensions of the sensor's active element. The system is designed to measure flows characterized by high velocity and temperature gradients, although its transmission bandwidth is very limited. In this study, we propose a method to optimize the two-state hot-wire anemometer transmission bandwidth. The method is based on the use of a specialized constanttemperature system together with variable dynamic parameters. It is also based on a suitable measurement cycle paradigm. Analysis of the method was undertaken using model testing. Our results reveal a possible significant broadening of the two-state hot-wire anemometer's transmission bandwidth.

  19. Amplifying modeling for broad bandwidth pulse in Nd:glass based on hybrid-broaden mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Sujingqin; Lanqin, L; Wenyi, W; Feng, J; Xiaofeng, W; Xiaomin, Z [Research Center of Laser Fusion, China Academy of Engineering Physics, P. O. Box 919-988, Mianyang, China, 621900 (China); Bin, L [School of Computer and Communication Engineering, Southwest Jiaotong University, Chengdu. China, 610031 (China)], E-mail: sujingqin@tom.com

    2008-05-15

    In this paper, the cross relaxation time is proposed to combine the homogeneous and inhomogeneous broaden mechanism for broad bandwidth pulse amplification model. The corresponding velocity equation, which can describe the response of inverse population on upper and low energy level of gain media to different frequency of pulse, is also put forward. The gain saturation and energy relaxation effect are also included in the velocity equation. Code named CPAP has been developed to simulate the amplifying process of broad bandwidth pulse in multi-pass laser system. The amplifying capability of multi-pass laser system is evaluated and gain narrowing and temporal shape distortion are also investigated when bandwidth of pulse and cross relaxation time of gain media are different. Results can benefit the design of high-energy PW laser system in LFRC, CAEP.

  20. Three-Dimensional Single-Port Labyrinthine Acoustic Metamaterial: Perfect Absorption with Large Bandwidth and Tunability

    Science.gov (United States)

    Zhang, Chi; Hu, Xinhua

    2016-12-01

    Metamaterials are engineered materials which exhibit fascinating properties unreachable by traditional materials. Here, we report on the design, fabrication, and experimental characterization of a three-dimensional single-port labyrinthine acoustic metamaterial. By using curled perforations with one end closed and with appropriate loss inside, the metamaterial can perfectly absorb airborne sounds in a low-frequency band. Both the position and the relative width of the band can be tuned flexibly. A trade-off is uncovered between the relative absorption bandwidth and thickness of the metamaterial. When the relative absorption bandwidth is as high as 51%, the requirement of deep-subwavelength thickness (0.07 λ ) can still be satisfied. We emphasize that the perfect absorption with large tunability in relative bandwidth (from 9% to >180 % ) was not attainable previously and may find applications ranging from noise reduction to sound imaging.

  1. Theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency

    Science.gov (United States)

    Liu, Yang; Li, Shu-qing; Feng, Zhong-ying; Liu, Xiao-fei; Gao, Jin-yue

    2016-12-01

    To obtain the weak signal light detection from the high background noise, we present a theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency. In a three-level Λ -type atomic system in the rubidium D1 line, the bandwidth of the EIT atomic filter is narrowed to ~6.5 \\text{MHz} . And the single peak transmission of the filter can be up to 86% . Moreover, the transmission wavelength can be tuned by changing the coupling light frequency. This theoretical scheme can also be applied to other alkali atomic systems.

  2. Metamaterial composite bandpass filter with an ultra-broadband rejection bandwidth of up to 240 terahertz

    DEFF Research Database (Denmark)

    Strikwerda, Andrew; Zalkovskij, Maksim; Lorenzen, Dennis Lund

    2014-01-01

    We present a metamaterial, consisting of a cross structure and a metal mesh filter, that forms a composite with greater functional bandwidth than any terahertz (THz) metamaterial to date. Metamaterials traditionally have a narrow usable bandwidth that is much smaller than common THz sources...... frequency (f) that is scalable from 0.86–8.51 THz, that highly extinguishes other frequencies up to >240 THz. The performance of these filters is demonstrated in experiment, using both air biased coherent detection and a Fourier transform infrared spectrometer (FTIR), as well as in simulation. We present...

  3. Vertical and lateral forces between a permanent magnet and a high-temperature superconductor

    Science.gov (United States)

    Hull, John R.; Cansiz, Ahmet

    1999-12-01

    The vertical and horizontal forces and associated stiffnesses on a permanent magnet (PM) above a high-temperature superconductor (HTS) were measured during vertical and horizontal traverses in zero-field cooling (ZFC) and in field cooling (FC). In ZFC, the vertical stiffness was greater in the first descent than in the first ascent and second descent, and the stiffness in the second descent was between those of the first descent and the first ascent. At the FC position, the vertical stiffness was two times greater than the lateral stiffness at each height, to within 1% of the vertical stiffness value. The cross stiffness of vertical force with respect to lateral position was positive for FC, but negative for ZFC. Free-spin-down experiments of a PM levitated above a HTS were also performed. These results showed that the coefficient of friction is double valued at frequencies just below the rotor resonance, a result attributed to cross stiffness in the PM/HTS interaction. A frozen-image model was used to calculate the vertical and horizontal forces and stiffnesses, and reasonable agreement with the data occurred for vertical or horizontal movements of the PM less than several mm from the FC position.

  4. A broadband x-ray imaging spectroscopy with high-angular resolution: the FORCE mission

    Science.gov (United States)

    Mori, Koji; Tsuru, Takeshi Go; Nakazawa, Kazuhiro; Ueda, Yoshihiro; Okajima, Takashi; Murakami, Hiroshi; Awaki, Hisamitsu; Matsumoto, Hironori; Fukazawa, Yasushi; Tsunemi, Hiroshi; Takahashi, Tadayuki; Zhang, William W.

    2016-07-01

    We are proposing FORCE (Focusing On Relativistic universe and Cosmic Evolution) as a future Japan-lead Xray observatory to be launched in the mid 2020s. Hitomi (ASTRO-H) possesses a suite of sensitive instruments enabling the highest energy-resolution spectroscopy in soft X-ray band, a broadband X-ray imaging spectroscopy in soft and hard X-ray bands, and further high energy coverage up to soft gamma-ray band. FORCE is the direct successor to the broadband X-ray imaging spectroscopy aspect of Hitomi (ASTRO-H) with significantly higher angular resolution. The current design of FORCE defines energy band pass of 1-80 keV with angular resolution of black holes" in various mass-scales: "buried supermassive black holes (SMBHs)" (> 104 M⊙) residing in the center of galaxies in a cosmological distance, "intermediate-mass black holes" (102-104 M⊙) acting as the possible seeds from which SMBHs grow, and "orphan stellar-mass black holes" (mirror and wide-band X-ray detector. The focal length is currently planned to be 10 m. The silicon mirror with multi-layer coating is our primary choice to achieve lightweight, good angular optics. The detector is a descendant of hard X-ray imager onboard Hitomi (ASTRO-H) replacing its silicon strip detector with SOI-CMOS silicon pixel detector, allowing an extension of the low energy threshold down to 1 keV or even less.

  5. Atomic force microscopy with nanoelectrode tips for high resolution electrochemical, nanoadhesion and nanoelectrical imaging

    Science.gov (United States)

    Nellist, Michael R.; Chen, Yikai; Mark, Andreas; Gödrich, Sebastian; Stelling, Christian; Jiang, Jingjing; Poddar, Rakesh; Li, Chunzeng; Kumar, Ravi; Papastavrou, Georg; Retsch, Markus; Brunschwig, Bruce S.; Huang, Zhuangqun; Xiang, Chengxiang; Boettcher, Shannon W.

    2017-03-01

    Multimodal nano-imaging in electrochemical environments is important across many areas of science and technology. Here, scanning electrochemical microscopy (SECM) using an atomic force microscope (AFM) platform with a nanoelectrode probe is reported. In combination with PeakForce tapping AFM mode, the simultaneous characterization of surface topography, quantitative nanomechanics, nanoelectronic properties, and electrochemical activity is demonstrated. The nanoelectrode probe is coated with dielectric materials and has an exposed conical Pt tip apex of ∼200 nm in height and of ∼25 nm in end-tip radius. These characteristic dimensions permit sub-100 nm spatial resolution for electrochemical imaging. With this nanoelectrode probe we have extended AFM-based nanoelectrical measurements to liquid environments. Experimental data and numerical simulations are used to understand the response of the nanoelectrode probe. With PeakForce SECM, we successfully characterized a surface defect on a highly-oriented pyrolytic graphite electrode showing correlated topographical, electrochemical and nanomechanical information at the highest AFM-SECM resolution. The SECM nanoelectrode also enabled the measurement of heterogeneous electrical conductivity of electrode surfaces in liquid. These studies extend the basic understanding of heterogeneity on graphite/graphene surfaces for electrochemical applications.

  6. A Wideband Supply Modulator for 20MHz RF Bandwidth Polar PAs in 65nm CMOS

    NARCIS (Netherlands)

    Shrestha, R.; van der Zee, Ronan A.R.; de Graauw, Anton; Nauta, Bram

    2009-01-01

    Polar modulated RF amplifiers have the potential to enhance efficiency while achieving sufficient linearity for a signal having non-constant envelope. However, switching modulators used in such architectures to generate the envelope signal are difficult to implement because of the high bandwidth and

  7. Facile preparation of superhydrophobic surface with high adhesive forces based carbon/silica composite films

    Indian Academy of Sciences (India)

    Ruanbing Hu; Guohua Jiang; Xiaohong Wang; Xiaoguang Xi; Rijing Wang

    2013-11-01

    Glass substrates modified by carbon/silica composites are fabricated through a two-step process for the preparation of a superhydrophobic surface (water contact angle ≥ 150°). Carbon nanoparticles were first prepared through a deposition process on glass using a hydrothermal synthesis route, then the glass was modified by SiO2 using the hydrolysis reaction of tetraethylorthosilicate at room temperature. It is not only a facile method to create a superhydrophobic surface, but also helps to form a multi-functional surface with high adhesive forces.

  8. Joining Forces: Collaborating Internationally to Deliver High-Quality, Online Postgraduate Education in Pain Management

    Directory of Open Access Journals (Sweden)

    Elizabeth Devonshire

    2011-01-01

    Full Text Available The effective management of pain is a complex and costly global issue, requiring a range of innovative educational strategies to enable culturally appropriate and high-quality health care provision. In response to this issue, the Pain Management Research Institute at the University of Sydney (Sydney, Australia has established several strategic alliances with other overseas universities to deliver online postgraduate education in pain management. The present article discusses the rationale for joining forces, and the approach adopted in creating and maintaining these alliances. It also provides insights into the benefits, challenges and opportunities associated with collaborative educational initiatives of this nature, from institutional, academic and student perspectives.

  9. Wide-area scanner for high-speed atomic force microscopy

    OpenAIRE

    Watanabe, Hiroki; Uchihashi, Takayuki; Kobashi, Toshihide; Shibata, Mikihiro; Nishiyama, Jun; Yasuda, Ryohei; Ando, Toshio

    2013-01-01

    High-speed atomic force microscopy (HS-AFM) has recently been established. The dynamic processes and structural dynamics of protein molecules in action have been successfully visualized using HS-AFM. However, its maximum scan ranges in the X- and Y-directions have been limited to ∼1 μm and ∼4 μm, respectively, making it infeasible to observe the dynamics of much larger samples, including live cells. Here, we develop a wide-area scanner with a maximum XY scan range of ∼46 × 46 μm2 by magnifyin...

  10. Influence of the lateral movement on the levitation and guidance force in the high-temperature superconductor maglev system

    Science.gov (United States)

    Song, Honghai; de Haas, Oliver; Beyer, Christoph; Krabbes, Gernot; Verges, Peter; Schultz, Ludwig

    2005-05-01

    After the levitation force relaxation was studied for different field-cooling height and working-levitation height, the high-temperature superconductor (HTS) bulk was horizontally moved in the lateral direction above the permanent magnet guideway. Both levitation and guidance force were collected by the measurement system at the same time. It was found that the decay of levitation force is dependent on both the maximum lateral displacement and the movement cycle times, while the guidance force hysteresis curve does not change after the first cycle. This work provided scientific analysis for the HTS maglev system design.

  11. Recommendations for a National High Blood Pressure Community Education Plan. Report of Task Force III--Community Education.

    Science.gov (United States)

    National Institutes of Health (DHEW), Bethesda, MD. High Blood Pressure Information Center.

    Hypertensive disease being one of the most important medical problems now facing American medicine brought about the formation of the Federally sponsored National High Blood Pressure Education Program, which included four Task Forces. Task Force 3 reviews in this study information and experience useful for the development of guidelines for…

  12. Forced canonical thermalization in a hadronic transport approach at high density

    Science.gov (United States)

    Oliinychenko, Dmytro; Petersen, Hannah

    2017-03-01

    Hadronic transport approaches based on an effective solution of the relativistic Boltzmann equation are widely applied for the dynamical description of heavy ion reactions at low beam energies. At high densities, the assumption of binary interactions often used in hadronic transport approaches may not be applicable anymore. Therefore, we effectively simulate the high-density regime using the local forced canonical thermalization. This framework provides the opportunity to interpolate in a dynamical way between two different limits of kinetic theory: the dilute gas approximation and the ideal fluid case. This approach will be important for studies of the dynamical evolution of heavy ion collisions at low and intermediate energies as experimentally investigated at the beam energy scan program at RHIC, and in the future at FAIR and NICA. On the other hand, this new way of modeling hot and dense strongly interacting matter might be relevant for small systems at high energies (LHC and RHIC) as well.

  13. High g-Force Rollercoaster Rides Induce Sinus Tachycardia but No Cardiac Arrhythmias in Healthy Children.

    Science.gov (United States)

    Pieles, Guido E; Husk, Victoria; Blackwell, Teresa; Wilson, Deirdre; Collin, Simon M; Williams, Craig A; Stuart, A Graham

    2017-01-01

    Theme park operators and medical professionals advise children with heart conditions against using rollercoaster rides, but these recommendations are not evidence-based. The underlying assumption is that the combination of adrenergic stimulation through stress and acceleration might trigger arrhythmias in susceptible individuals. We conducted a cross-sectional observational study to assess heart rate and rhythm in healthy children during commercial rollercoaster rides. Twenty healthy children (9 male) aged 11-15 (mean 13.3 ± 1.4) years underwent continuous heart rate and rhythm monitoring (2-lead ECG) from 5 min before until 10 min after each of 4 high speed (>50 km h(-1)), high g-force (>4) commercial rollercoaster rides. Total recording time was 13 h 20 min. No arrhythmic events were detected. Resting heart rate was 81 ± 10 b min(-1) and increased to 158 ± 20 b·min(-1) during rides. The highest mean HR (165 ± 23 b min(-1)) was observed on the ride with the lowest g-force (4.5 g), but one of the highest speeds (100 km h(-1)). Anticipatory tachycardia (126 ± 15 b min(-1)) within 5 min was frequently observed. A 10 min recovery HR (124 ± 17 b min(-1)) was 56 % greater than resting HR. The speed and g-force experienced on roller coasters induce sinus tachycardia but do not elicit pathological arrhythmias in healthy children.

  14. Bandwidth enhancement of MgZnO-based MSM photodetectors by inductive gain peaking

    Science.gov (United States)

    Wang, Ping; Guo, Xinlu; Guo, Lixin; He, Jingfang; Yang, Yintang; Zhang, Zhiyong

    2016-08-01

    For high-speed optical communication applications, the bandwidth of photodetector would be a key limitation. In this work, the bandwidth property of MgZnO-based Metal-Semiconductor-Metal (MSM) photodetector considering RC and transit limitations is investigated on the basis of the series and enhanced gain peaked photodetector circuits proposed by us with different finger widths. To ensure the accuracy of parameters, the high-filed transportation characteristics of MgZnO are investigated by a three-valley ensemble Monte Carlo simulation combined with first principle calculations. The results show that the gain peaking technique, especially the enhanced gain peaking, can improve the bandwidth of MgZnO MSM photodetector to a maximum value of 61.28 GHz, corresponding to a bandwidth enhancement of 49% without undesired effects. Three-dimensional electromagnetic computation is further performed to design and simulate the on-chip-inductor. The value of the simulated inductor is approximately 0.0529 nH, which is in good agreement with the designed value of 0.0569 nH. This work benefits the development of high speed MgZnO MSM photodetector.

  15. Staged optimization algorithms based MAC dynamic bandwidth allocation for OFDMA-PON

    Science.gov (United States)

    Liu, Yafan; Qian, Chen; Cao, Bingyao; Dun, Han; Shi, Yan; Zou, Junni; Lin, Rujian; Wang, Min

    2016-06-01

    Orthogonal frequency division multiple access passive optical network (OFDMA-PON) has being considered as a promising solution for next generation PONs due to its high spectral efficiency and flexible bandwidth allocation scheme. In order to take full advantage of these merits of OFDMA-PON, a high-efficiency medium access control (MAC) dynamic bandwidth allocation (DBA) scheme is needed. In this paper, we propose two DBA algorithms which can act on two different stages of a resource allocation process. To achieve higher bandwidth utilization and ensure the equity of ONUs, we propose a DBA algorithm based on frame structure for the stage of physical layer mapping. Targeting the global quality of service (QoS) of OFDMA-PON, we propose a full-range DBA algorithm with service level agreement (SLA) and class of service (CoS) for the stage of bandwidth allocation arbitration. The performance of the proposed MAC DBA scheme containing these two algorithms is evaluated using numerical simulations. Simulations of a 15 Gbps network with 1024 sub-carriers and 32 ONUs demonstrate the maximum network throughput of 14.87 Gbps and the maximum packet delay of 1.45 ms for the highest priority CoS under high load condition.

  16. Bandwidth auction for SVC streaming in dynamic multi-overlay

    Science.gov (United States)

    Xiong, Yanting; Zou, Junni; Xiong, Hongkai

    2010-07-01

    In this paper, we study the optimal bandwidth allocation for scalable video coding (SVC) streaming in multiple overlays. We model the whole bandwidth request and distribution process as a set of decentralized auction games between the competing peers. For the upstream peer, a bandwidth allocation mechanism is introduced to maximize the aggregate revenue. For the downstream peer, a dynamic bidding strategy is proposed. It achieves maximum utility and efficient resource usage by collaborating with a content-aware layer dropping/adding strategy. Also, the convergence of the proposed auction games is theoretically proved. Experimental results show that the auction strategies can adapt to dynamic join of competing peers and video layers.

  17. Ultra-broad bandwidth parametric amplification at degeneracy.

    Science.gov (United States)

    Limpert, J; Aguergaray, C; Montant, S; Manek-Hönninger, I; Petit, S; Descamps, D; Cormier, E; Salin, F

    2005-09-19

    We report on a novel approach of ultra-broad bandwidth parametric amplification around degeneracy. A bandwidth of up to 400 nm centered around 800 nm is amplified in a BBO crystal by using chirped pump pulses with a bandwitdth as broad as 10 nm. A supercontinuum signal is generated in a microstructured fiber, having to first order a quadratic chirp, which is necessary to ensure temporal overlap of the interacting waves over this broad bandwidth. Furthermore, we discuss the potential of this approach for an octave-spanning parametric amplification.

  18. Energy efficiency in elastic-bandwidth optical networks

    DEFF Research Database (Denmark)

    Vizcaino, Jorge Lopez; Ye, Yabin; Tafur Monroy, Idelfonso

    2011-01-01

    The forecasted growth in the Internet traffic has made the operators and industry to be concerned about the power consumption of the networks, and to become interested in alternatives to plan and operate the networks in a more energy efficient manner. The introduction of OFDM, and its property...... of elastic bandwidth allocation, opens new horizons in the operation of optical networks. In this paper, we compare the network planning problem in an elastic bandwidth CO-OFDM-based network and a fixed-grid WDM network. We highlight the benefits that bandwidth elasticity and the selection of different...

  19. Efficiently parallelized modeling of tightly focused, large bandwidth laser pulses

    Science.gov (United States)

    Dumont, Joey; Fillion-Gourdeau, François; Lefebvre, Catherine; Gagnon, Denis; MacLean, Steve

    2017-02-01

    The Stratton-Chu integral representation of electromagnetic fields is used to study the spatio-temporal properties of large bandwidth laser pulses focused by high numerical aperture mirrors. We review the formal aspects of the derivation of diffraction integrals from the Stratton-Chu representation and discuss the use of the Hadamard finite part in the derivation of the physical optics approximation. By analyzing the formulation we show that, for the specific case of a parabolic mirror, the integrands involved in the description of the reflected field near the focal spot do not possess the strong oscillations characteristic of diffraction integrals. Consequently, the integrals can be evaluated with simple and efficient quadrature methods rather than with specialized, more costly approaches. We report on the development of an efficiently parallelized algorithm that evaluates the Stratton-Chu diffraction integrals for incident fields of arbitrary temporal and spatial dependence. This method has the advantage that its input is the unfocused field coming from the laser chain, which is experimentally known with high accuracy. We use our method to show that the reflection of a linearly polarized Gaussian beam of femtosecond duration off a high numerical aperture parabolic mirror induces ellipticity in the dominant field components and generates strong longitudinal components. We also estimate that future high-power laser facilities may reach intensities of {10}24 {{W}} {{cm}}-2.

  20. Receptivity and Forced Response to Acoustic Disturbances in High-Speed Boundary Layers

    Science.gov (United States)

    Balakumar, P.; King, Rudolph A.; Chou, Amanda; Owens, Lewis R.; Kegerise, Michael A.

    2016-01-01

    Supersonic boundary-layer receptivity to freestream acoustic disturbances is investigated by solving the Navier-Stokes equations for Mach 3.5 flow over a sharp flat plate and a 7-deg half-angle cone. The freestream disturbances are generated from a wavy wall placed at the nozzle wall. The freestream acoustic disturbances radiated by the wavy wall are obtained by solving the linearized Euler equations. The results for the flat plate show that instability modes are generated at all the incident angles ranging from zero to highly oblique. However, the receptivity coefficient decreases by about 20 times when the incident angle increases from zero to a highly oblique angle of 68 degrees. The results for the cone show that no instability modes are generated when the acoustic disturbances impinge the cone obliquely. The results show that the perturbations generated inside the boundary layer by the acoustic disturbances are the response of the boundary layer to the external forcing. The amplitude of the forced disturbances inside the boundary layer are about 2.5 times larger than the incoming field for zero azimuthal wavenumber and they are about 1.5 times for large azimuthal wavenumbers.

  1. LLW disposal wasteform preparation in the UK: the role of high force compaction

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, L. F.; Fearnley, I. G. [British Nuclear Fuels Ltd., Sellafield (United Kingdom)

    1991-07-01

    British Nuclear Fuels plc (BNFL) owns and operates the principal UK solid low level radioactive waste (LLW) disposal site. The site is located at Drigg in West Cumbria some 6 km to the south east of BNFL's Sellafield reprocessing complex. Sellafield is the major UK generator of LLW, accounting for about 85% of estimated future arisings of raw (untreated, unpackaged) waste. Non-Sellafield consignors to the Drigg site include other BNFL production establishments, nuclear power stations, sites of UKAEA, Ministry of Defence facilities, hospitals, universities, radioisotope production sites and various other industrial organisations. In September 1987, BNFL announced a major upgrade of operations at the Drigg site aimed at improving management practices, the efficiency of space utilisation and enhancing the visual impact of disposal operations. During 1989 a review of plans for compaction and containerisation of Sellafield waste identified that residual voidage in ISO freight containers could be significant even after the introduction of compaction. Subsequent studies which examined a range of compaction and packaging options concluded that the preferred scheme centred on the use of high force compaction (HFC) of compactable waste, and grouting to take up readily accessible voidage in the wasteform. The paper describes the emergence of high force compaction as the preferred scheme for wasteform preparation and subsequent benefits against the background of the overall development of Low Level Waste disposal operations at Drigg.

  2. Cutting force and its frequency spectrum characteristics in high speed milling of titanium alloy with a polycrystalline diamond tool

    Institute of Scientific and Technical Information of China (English)

    Peng LIU; Jiu-hua XU; Yu-can FU

    2011-01-01

    In this paper, a series of experiments were performed by high speed milling of Ti-6.5Al-2Zr-1Mo-1V(TA15)by use of polycrystalline diamond(PCD)tools. The characteristics of high speed machining(HSM)dynamic milling forces were investigated. The effects of the parameters of the process, I.e., cutting speed, feed per tooth, and depth of axial cut, on cutting forces were studied. The cutting force signals under different cutting speed conditions and different cutting tool wear stages were analyzed by frequency spectrum analysis. The trend and frequency domain aspects of the dynamic forces were evaluated and discussed. The results indicate that a characteristic frequency in cutting force power spectrum does in fact exist. The amplitudes increase with the increase of cutting speed and tool wear level, which could be applied to the monitoring of the cutting process.

  3. Synthesis of one-molecule-thick single-crystalline nanosheets of energetic material for high-sensitive force sensor.

    Science.gov (United States)

    Yang, Guangcheng; Hu, Hailong; Zhou, Yong; Hu, Yingjie; Huang, Hui; Nie, Fude; Shi, Weimei

    2012-01-01

    Energetic material is a reactive substance that contains a great amount of potential energy, which is extremely sensitive to external stimuli like force. In this work, one-molecule-thick single-crystalline nanosheets of energetic material were synthesized. Very small force applied on the nanosheet proves to lead to the rotation of the tilted nitro groups, and subsequently change of current of the nanosheet. We apply this principle to design high-sensitive force sensor. A theoretical model of force-current dependence was established based on the nanosheets' molecular packing structure model that was well supported with the high resolution XPS, AFM analysis results. An ultra-low-force with range of several picoNewton to several nanoNewton can be measured by determination of corresponding current value.

  4. Evaluation and optimization of quartz resonant-frequency retuned fork force sensors with high Q factors, and the associated electric circuits, for non-contact atomic force microscopy.

    Science.gov (United States)

    Ooe, Hiroaki; Fujii, Mikihiro; Tomitori, Masahiko; Arai, Toyoko

    2016-02-01

    High-Q factor retuned fork (RTF) force sensors made from quartz tuning forks, and the electric circuits for the sensors, were evaluated and optimized to improve the performance of non-contact atomic force microscopy (nc-AFM) performed under ultrahigh vacuum (UHV) conditions. To exploit the high Q factor of the RTF sensor, the oscillation of the RTF sensor was excited at its resonant frequency, using a stray capacitance compensation circuit to cancel the excitation signal leaked through the stray capacitor of the sensor. To improve the signal-to-noise (S/N) ratio in the detected signal, a small capacitor was inserted before the input of an operational (OP) amplifier placed in an UHV chamber, which reduced the output noise from the amplifier. A low-noise, wideband OP amplifier produced a superior S/N ratio, compared with a precision OP amplifier. The thermal vibrational density spectra of the RTF sensors were evaluated using the circuit. The RTF sensor with an effective spring constant value as low as 1000 N/m provided a lower minimum detection limit for force differentiation. A nc-AFM image of a Si(111)-7 × 7 surface was produced with atomic resolution using the RTF sensor in a constant frequency shift mode; tunneling current and energy dissipation images with atomic resolution were also simultaneously produced. The high-Q factor RTF sensor showed potential for the high sensitivity of energy dissipation as small as 1 meV/cycle and the high-resolution analysis of non-conservative force interactions.

  5. High Speed Photography, Videography, And Photonic Instrumentation Development At The Air Force Armament Laboratory

    Science.gov (United States)

    Snyder, Donald R.; Powell, Rodney M.

    1989-02-01

    The Instrumentation Technology Branch of the Air Force Armament Laboratory is currently involved in the development of several high speed photographic, videographic, and photonic instrumentation systems to support the testing and analysis of developmental weapons and test items under dynamic conditions. These projects include development of a large format (14 inch by 17 inch) laser illuminated Cranz-Schardin shadowgraph system for materials research, development of a solid state imager based shadowgraph system for aeroballistic studies, experiments with gated imagers for a variety of test applications, and experiments with high speed video imagers and illuminators for airborne and range tracking instrumentation. An additional issue discussed is the development of a timing and annotation standard for video imaging instrumentation systems operating at higher than NTSC standard rates.

  6. Modulation bandwidth enhancement of white-LED-based visible light communications using electrical equalizations

    Science.gov (United States)

    Kwon, D. H.; Yang, S. H.; Han, S. K.

    2015-01-01

    Utilizing the modulation capability of LEDs, there have been many studies about convergence technology to combine illumination and communication. The visible light communication (VLC) system has several advantages such as high security, immunity to RF interference and lower additional cost than comparing to LEDs just for illumination. However, modulation bandwidth of LEDs is not enough for various wireless communication systems. Since the commercial LEDs are designed only for lighting systems; we need an effort to enhance the modulation characteristics of LEDs. When the area of LED is increased, internal junction capacitance of LED is also increased depending on the area of LEDs and then the RC delay time of LED is increased. As a result, the modulation bandwidth of LEDs is limited by large RC delay time. In addition, frequency response of commercial white LED is degraded by the slow response time of the used yellow phosphor. Thus, modulation bandwidth of VLC system is limited to several MHz which is not enough to accommodate high data rate transmission. In this paper, we designed equalization circuit using RLC component for compensating the white LEDs frequency response. Also, we used blue filtering to improve frequency response of white LEDs, which is degraded by yellow phosphorescent component. Power loss by optical filtering and distance is compensated by convex lens. Consequently, we extend the modulation bandwidth of VLC system from 3 MHz to more than 180 MHz, and it allows NRZ-OOK data transmission up to 400 Mbps at 50 cm.

  7. Dynamics of highly-flexible solar sail subjected to various forces

    Science.gov (United States)

    Liu, Jiafu; Cui, Naigang; Shen, Fan; Rong, Siyuan

    2014-10-01

    Solar sail is a novel spacecraft and has the potential applications in the near future. The large amplitude vibration should be considered because it is characterized by its huge and lightweight structure. In this paper, the supporting beam of solar sail is regarded as the most important structure and used to model the sailcraft as it accounts for most of the mechanical energies when it is in deformed configuration, also as the Euler beam can model the bending motion dominant sailcraft when it experiences attitude motions. The structural dynamics of solar sail supporting beam with geometric nonlinearity undergoing the forces generated by solar radiation pressure, sliding masses and control vanes are presented. The axial and transverse vibration equations with the properties of strong coupling, nonlinearity and time-varying coefficient matrices are obtained by using Lagrange equation method after calculating the related energies and works. The vibration equations are transformed into nonlinear algebraic equations utilizing implicit unconditionally stable Newmark-β algorithm for each time step. The nonlinear algebraic equations are solved by Newton-iterative algorithm. We compute and analyze the linear and nonlinear vibration responses affected by the mass and velocity of the sliding mass, the angular velocity of the force generated by control vane in detail. The computational results indicate that the mass and velocity of sliding mass affect the vibration responses (including the vibration frequency), but the angular velocity of the force generated by control vane hardly affects the vibration responses. Moreover, the linear and nonlinear vibrations are distinct obviously by comparing the linear and nonlinear responses. It is demonstrated that the geometric nonlinearity of the highly-flexible structure should be considered for performing vibration analysis exactly, and the vibration responses excited by the prescribed motion of the attitude control actuators should

  8. Effect of high-intensity interval training on cardiovascular function, VO2max, and muscular force.

    Science.gov (United States)

    Astorino, Todd A; Allen, Ryan P; Roberson, Daniel W; Jurancich, Matt

    2012-01-01

    The purpose of this study was to examine the effects of short-term high-intensity interval training (HIIT) on cardiovascular function, cardiorespiratory fitness, and muscular force. Active, young (age and body fat = 25.3 ± 4.5 years and 14.3 ± 6.4%) men and women (N = 20) of a similar age, physical activity, and maximal oxygen uptake (VO2max) completed 6 sessions of HIIT consisting of repeated Wingate tests over a 2- to 3-week period. Subjects completed 4 Wingate tests on days 1 and 2, 5 on days 3 and 4, and 6 on days 5 and 6. A control group of 9 men and women (age and body fat = 22.8 ± 2.8 years and 15.2 ± 6.9%) completed all testing but did not perform HIIT. Changes in resting blood pressure (BP) and heart rate (HR), VO2max, body composition, oxygen (O2) pulse, peak, mean, and minimum power output, fatigue index, and voluntary force production of the knee flexors and extensors were examined pretraining and posttraining. Results showed significant (p VO2max, O2 pulse, and Wingate-derived power output with HIIT. The magnitude of improvement in VO2max was related to baseline VO2max (r = -0.44, p = 0.05) and fatigue index (r = 0.50, p 0.05) in resting BP, HR, or force production was revealed. Data show that HIIT significantly enhanced VO2max and O2 pulse and power output in active men and women.

  9. SIMULATION STUDY OF AERODYNAMIC FORCE FOR HIGH-SPEED MAGNETICALLY-LEVITATED TRAINS

    Institute of Scientific and Technical Information of China (English)

    LI Renxian; LIU Yingqing; ZHAI Wanming

    2006-01-01

    Based on Reynolds average Navier-Storkes equations of viscous incompressible fluid and k-ε two equations turbulent model, the aerodynamic forces of high-speed magnetically-levitated(maglev) trains in transverse and longitudinal wind are investigated by finite volume method. Near 80 calculation cases for 2D transverse wind fields and 20 cases for 3D longitudinal wind fields are and lyzed. The aerodynamic side force, yawing, drag, lift and pitching moment for different types of maglev trains and a wheel/rail train are compared under the different wind speeds. The types of maglev train models for 2D transverse wind analysis included electromagnetic suspension (EMS) type train,electrodynamic suspension (EDS) type train, EMS type train with shelter wind wall in one side or two sides of guideway and the walls, which are in different height or/and different distances from train body. The situation of maglev train running on viaduct is also analyzed. For 3D longitudinal wind field analysis, the model with different sizes of air clearances beneath maglev train is examined for the different speeds. Calculation result shows that: ① Different transverse effects are shown in different types of maglev trains. ② The shelter wind wall can fairly decrease the transverse effect on the maglev train. ③ When the shelter wall height is 2 m, there is minimum side force on the train.When the shelter wall height is 2.5 m, there is minimum yawing moment on the train. ④ When the distance between inside surfaces of the walls and center of guideway is 4.0 m, there is minimum transverse influence on the train. ⑤ The size of air clearance beneath train body has a small influence on aerodynamic drag of the train, but has a fairly large effect on aerodynamic lift and pitching moment of the train. ⑥ The calculating lift and pitching moment for maglev train models are minus values.

  10. Bandwidth allocation and pricing problem for a duopoly market

    Directory of Open Access Journals (Sweden)

    You Peng-Sheng

    2011-01-01

    Full Text Available This research discusses the Internet service provider (ISP bandwidth allocation and pricing problems for a duopoly bandwidth market with two competitive ISPs. According to the contracts between Internet subscribers and ISPs, Internet subscribers can enjoy their services up to their contracted bandwidth limits. However, in reality, many subscribers may experience the facts that their on-line requests are denied or their connection speeds are far below their contracted speed limits. One of the reasons is that ISPs accept too many subscribers as their subscribers. To avoid this problem, ISPs can set limits for their subscribers to enhance their service qualities. This paper develops constrained nonlinear programming to deal with this problem for two competitive ISPs. The condition for reaching the equilibrium between the two competitive firms is derived. The market equilibrium price and bandwidth resource allocations are derived as closed form solutions.

  11. Available Bandwidth Estimation Strategy Based on the Network Allocation Vector

    Directory of Open Access Journals (Sweden)

    Hongtao Liu

    2012-12-01

    Full Text Available Available bandwidth is of great importance to network Quality of Service assurance, network load balancing, streaming media rate control, routing, and congestion control, etc.. In this paper, the available bandwidth estimation strategy based on the Network Allocation Vector for Wireless Sensor Networks is proposed. According to the size of the average contention window, network nodes predict the probability of collision in process of frame transmission, and then estimate the number of retransmission. Through the collection of Hello packets periodically sent by neighbors, nodes obtain their Network Allocation Vector, and then estimate the available bandwidth. The simulation results show that the strategy is simple and effective, can accurately estimate the collision of data frames as well as the available bandwidth of Wireless Sensor Networks.

  12. Low and Expensive Bandwidth Remains Key Bottleneck for ...

    African Journals Online (AJOL)

    PROF. O. E. OSUAGWU

    2013-06-01

    Jun 1, 2013 ... + Department of Computer Science, Imo State University + South Eastern College of Computer ... The National Communications Commission (NCC) which is the Apex body that .... Low bandwidth slows down data transfer.

  13. An Improved Dynamic Bandwidth Allocation Algorithm for Ethernet PON

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    This paper proposes an improved Dynamic Bandwidth Allocation (DBA) algorithm for EPON, which combines static and traditional dynamic allocation schemes. Simulation result shows that the proposed algorithm may effectively improve the performance of packet delay.

  14. Radiation Bandwidth Improvement of Electromagnetic Band Gap Cavity Antenna

    Science.gov (United States)

    Chaabane, Abdelhalim; Djahli, Farid; Attia, Hussein; Denidni, Tayeb. A.

    2017-09-01

    In this paper, an electromagnetic band gap cavity antenna with improved radiation and impedance bandwidths is presented. The proposed antenna is constructed by placing a triple-layer heterogeneous printed-unprinted partially reflective surface (PRS) above a primary aperture-coupled patch antenna. The PRS unit-cell provides a positive gradient reflection phase behavior over the desired frequency range. A prototype antenna is fabricated and measured that highlighted its ability to achieve 3-dB gain bandwidth of about 35.9 %, from 7.93 GHz to 11.4 GHz, with a peak gain of 14.25 dBi at 8.5 GHz. In addition, the impedance bandwidth is 40.32 %, from 7.9 GHz to 11.89 GHz. Thus, the designed antenna outperforms many other competitors for improving the radiation bandwidth of planar antennas with the same presented concept.

  15. MULTILAYER MICROSTRIP ANTENNA QUALITY FACTOR OPTIMIZATION FOR BANDWIDTH ENHANCEMENT

    Directory of Open Access Journals (Sweden)

    M.C. SRIVASTAVA

    2012-12-01

    Full Text Available The impedance bandwidth, one of the important characteristics of microstrip patch antennas, can be significantly improved by using a multilayer dielectric configuration. In this paper the focus is on bandwidth enhancement technique of a multilayer patch antenna for X-band applications. In order to enhance the bandwidth, antenna losses are contained by controlling those quality factors which can have a significant impact on the bandwidth for a given permittivity and thickness of the substrate. This has been achieved by conformal transformation of the multidielectric microstrip antenna. For the ease of analysis Wheelers transformation is used to map the complex permittivity of a multilayer substrate to a single layer. Method of Moments and Finite Difference Time Domain approaches are used for the computation of results.

  16. Bandwidth Estimation in Wireless Lans for Multimedia Streaming Services

    Directory of Open Access Journals (Sweden)

    Heung Ki Lee

    2007-01-01

    Full Text Available The popularity of multimedia streaming services via wireless networks presents major challenges in the management of network bandwidth. One challenge is to quickly and precisely estimate the available bandwidth for the decision of streaming rates of layered and scalable multimedia services. Previous studies based on wired networks are too burdensome to be applied to multimedia applications in wireless networks. In this paper, a new method, IdleGap, is suggested to estimate the available bandwidth of a wireless LAN based on the information from a low layer in the protocol stack. We use a network simulation tool, NS-2, to evaluate our new method with various ranges of cross-traffic and observation times. Our simulation results show that IdleGap accurately estimates the available bandwidth for all ranges of cross-traffic (100 Kbps ∼ 1 Mbps with a very short observation time of 10 seconds.

  17. High intensity interior aircraft noise increases the risk of high diastolic blood pressure in Indonesian Air Force pilots

    Directory of Open Access Journals (Sweden)

    Minarma Siagian

    2009-12-01

    Full Text Available Aim: To analyze the effects of aircraft noise, resting pulse rate, and other factors on the risk of high diastolic blood pressure (DBP in Indonesian Air Force pilots.Methods: A nested case-control study was conducted using data extracted from annual medical check-ups indoctrination aerophysiologic training records at the Saryanto Aviation and Aerospace Health Institute (LAKESPRA in Jakarta from January 2003 – September 2008. For analysis of DBP: the case group with DBP ≥ 90 mmHg were compared with contral group with DBP < 79 mmHG. One case matched to 12 controls.Results: Out of 567 pilots, 544 (95.9% had complete medical records. For this analysis there were 40 cases of high DBP and 480 controls for DBP. Pilots exposed to aircraft noise 90-95 dB rather than 70-80 dB had a 2.7-fold increase for high DBP [adjusted odds ratio (ORa = 2.70; 95% confi dence interval (CI = 1.05-6.97]. Pilots with resting pulse rates of ≥ 81/minute rather than ≤ 80/minute had a 2.7-fold increase for high DBP (ORa = 2.66; 95% CI = 1.26-5.61. In terms of total fl ight hours, pilots who had 1401-11125 hours rather than 147-1400 hours had a 3.2-fold increase for high DBP (ORa = 3.18; 95% CI = 1.01-10.03.Conclusion: High interior aircraft noise, high total flight hours,  and high resting pulse rate, increased risk for high DBP. Self assessment of resting pulse rate can be used to control the risk of high DBP. (Med J Indones 2009; 276: 276-82Keywords: diastolic blood pressure, aircraft noise, resting pulse rate, military pilots

  18. Laser frequency bandwidth narrowing by photorefractive two-beam coupling.

    Science.gov (United States)

    Chomsky, D; Sternklar, S; Zigler, A; Jackel, S

    1992-04-01

    We present a theoretical analysis and experimental demonstration of a new method for spectral narrowing of laser radiation. The bandwidth narrowing is experienced by a laser beam subjected to a photorefractive two-beam coupling process. Contrary to the conventional method of frequency filtering by a Fabry-Perot étalon, this technique has no intrinsic finesse limitation on its resolution. A factor of 2 in frequency bandwidth narrowing is achieved with an argon-ion laser.

  19. Lightweight monitoring of label switched paths for bandwidth management

    OpenAIRE

    Vilà Talleda, Pere; Marzo i Lázaro, Josep Lluís; Calle Ortega, Eusebi; Carrillo, Liliana

    2004-01-01

    The purpose of resource management is the efficient and effective use of network resources, for instance bandwidth. In this article, a connection oriented network scenario is considered, where a certain amount of bandwidth is reserved for each label switch path (LSP), which is a logical path, in a MPLS or GMPLS environment. Assuming there is also some kind of admission control (explicit or implicit), these environments typically provide quality of service (QoS) guarantees. It could happen tha...

  20. A meta-substrate to enhance the bandwidth of metamaterials

    OpenAIRE

    Hongsheng Chen; Zuojia Wang; Runren Zhang; Huaping Wang; Shisheng Lin; Faxin Yu; Moser, Herbert O.

    2014-01-01

    We propose the concept of a meta-substrate to broaden the bandwidth of left-handed metamaterials. The meta-substrate, which behaves like an inhomogeneous magnetic substrate, is composed of another kind of magnetic metamaterials like metallic closed rings. When conventional metamaterial rings are printed on this kind of meta-substrate in a proper way, the interaction of the metamaterials units can be greatly enhanced, yielding an increased bandwidth of negative permeability. An equivalent circ...

  1. Bandwidth-Efficient Cooperative Relaying Schemes with Multiantenna Relay

    Directory of Open Access Journals (Sweden)

    Tho Le-Ngoc

    2008-05-01

    Full Text Available We propose coded cooperative relaying schemes in which all successfully decoded signals from multiple sources are forwarded simultaneously by a multiantenna relay to a common multiantenna destination to increase bandwidth efficiency. These schemes facilitate various retransmission strategies at relay and single-user and multiuser iterative decoding techniques at destination, suitable for trade-offs between performance, latency, and complexity. Simulation results show that the proposed schemes significantly outperform direct transmission under the same transmit power and bandwidth efficiency.

  2. Independent component analysis of high-density electromyography in muscle force estimation.

    NARCIS (Netherlands)

    Staudenmann, D.; Daffertshofer, A.; Kingma, I.; Stegeman, D.F.; Dieen, J.H. van

    2007-01-01

    Accurate force prediction from surface electromyography (EMG) forms an important methodological challenge in biomechanics and kinesiology. In a previous study (Staudenmann et al., 2006), we illustrated force estimates based on analyses lent from multivariate statistics. In particular, we showed the

  3. Modeling and Application of Series Elastic Actuators for Force Control Multi Legged Robots

    CERN Document Server

    S, Arumugom; V, Ponselvan

    2009-01-01

    Series Elastic Actuators provide many benefits in force control of robots in unconstrained environments. These benefits include high force fidelity, extremely low impedance, low friction, and good force control bandwidth. Series Elastic Actuators employ a novel mechanical design architecture which goes against the common machine design principal of "stiffer is better". A compliant element is placed between the gear train and driven load to intentionally reduce the stiffness of the actuator. A position sensor measures the deflection, and the force output is accurately calculated using Hooke's Law (F=Kx). A control loop then servos the actuator to the desired output force. The resulting actuator has inherent shock tolerance, high force fidelity and extremely low impedance. These characteristics are desirable in many applications including legged robots, exoskeletons for human performance amplification, robotic arms, haptic interfaces, and adaptive suspensions. We describe several variations of Series Elastic Ac...

  4. Large surface radiative forcing from topographic blowing snow residuals measured in the High Arctic at Eureka

    Directory of Open Access Journals (Sweden)

    G. Lesins

    2009-03-01

    Full Text Available Ice crystals, also known as diamond dust, are suspended in the boundary layer air under clear sky conditions during most of the Arctic winter in Northern Canada. Occasionally ice crystal events can produce significantly thick layers with optical depths in excess of 2.0 even in the absence of liquid water clouds. Four case studies of high optical depth ice crystal events at Eureka in the Nunavut Territory of Canada during the winter of 2006/07 are presented. They show that the measured ice crystal surface infrared downward radiative forcing ranged from 8 to 36 W m−2 in the wavelength band from 5.6 to 20 μm for 532 nm optical depths ranging from 0.2 to 1.7. MODIS infrared and visible images and the operational radiosonde wind profile were used to show that these high optical depth events were caused by surface snow being blown off 600 to 800 m high mountain ridges about 20 to 30 km North-West of Eureka and advected by the winds towards Eureka as they settled towards the ground within the highly stable boundary layer. This work presents the first study that demonstrates the important role that surrounding topography plays in determining the occurrence of high optical depth ice crystal events from residual blowing snow that becomes a source of boundary layer ice crystals distinct from the classical diamond dust phenomenon.

  5. Modeling of stochastic dynamics of time-dependent flows under high-dimensional random forcing

    Science.gov (United States)

    Babaee, Hessam; Karniadakis, George

    2016-11-01

    In this numerical study the effect of high-dimensional stochastic forcing in time-dependent flows is investigated. To efficiently quantify the evolution of stochasticity in such a system, the dynamically orthogonal method is used. In this methodology, the solution is approximated by a generalized Karhunen-Loeve (KL) expansion in the form of u (x , t ω) = u ̲ (x , t) + ∑ i = 1 N yi (t ω)ui (x , t) , in which u ̲ (x , t) is the stochastic mean, the set of ui (x , t) 's is a deterministic orthogonal basis and yi (t ω) 's are the stochastic coefficients. Explicit evolution equations for u ̲ , ui and yi are formulated. The elements of the basis ui (x , t) 's remain orthogonal for all times and they evolve according to the system dynamics to capture the energetically dominant stochastic subspace. We consider two classical fluid dynamics problems: (1) flow over a cylinder, and (2) flow over an airfoil under up to one-hundred dimensional random forcing. We explore the interaction of intrinsic with extrinsic stochasticity in these flows. DARPA N66001-15-2-4055, Office of Naval Research N00014-14-1-0166.

  6. Characterization of the surface charge distribution on kaolinite particles using high resolution atomic force microscopy

    Science.gov (United States)

    Kumar, Naveen; Zhao, Cunlu; Klaassen, Aram; van den Ende, Dirk; Mugele, Frieder; Siretanu, Igor

    2016-02-01

    Most solid surfaces, in particular clay minerals and rock surfaces, acquire a surface charge upon exposure to an aqueous environment due to adsorption and/or desorption of ionic species. Macroscopic techniques such as titration and electrokinetic measurements are commonly used to determine the surface charge and ζ -potential of these surfaces. However, because of the macroscopic averaging character these techniques cannot do justice to the role of local heterogeneities on the surfaces. In this work, we use dynamic atomic force microscopy (AFM) to determine the distribution of surface charge on the two (gibbsite-like and silica-like) basal planes of kaolinite nanoparticles immersed in aqueous electrolyte with a lateral resolution of approximately 30 nm. The surface charge density is extracted from force-distance curves using DLVO theory in combination with surface complexation modeling. While the gibbsite-like and the silica-like facet display on average positive and negative surface charge values as expected, our measurements reveal lateral variations of more than a factor of two on seemingly atomically smooth terraces, even if high resolution AFM images clearly reveal the atomic lattice on the surface. These results suggest that simple surface complexation models of clays that attribute a unique surface chemistry and hence homogeneous surface charge densities to basal planes may miss important aspects of real clay surfaces.

  7. High harmonic interferometry of the Lorentz force in strong mid-infrared laser fields

    CERN Document Server

    Pisanty, Emilio; Galloway, Benjamin R; Durfee, Charles G; Kapteyn, Henry C; Murnane, Margaret M; Ivanov, Misha

    2016-01-01

    The interaction of intense mid-infrared laser fields with atoms and molecules leads to a range of new opportunities, from the production of bright, coherent radiation in the soft x-ray range to imaging molecular structures and dynamics with attosecond temporal and sub-angstrom spatial resolution. However, all these effects, which rely on laser-driven recollision of an electron removed by the strong laser field and the parent ion, suffer from the rapidly increasing role of the magnetic field component of the driving pulse: the associated Lorentz force pushes the electrons off course in their excursion and suppresses all recollision-based processes, including high harmonic generation, elastic and inelastic scattering. Here we show how the use of two non-collinear beams with opposite circular polarizations produces a forwards ellipticity which can be used to monitor, control, and cancel the effect of the Lorentz force. This arrangement can thus be used to re-enable recollision-based phenomena in regimes beyond t...

  8. Design and Analysis of a High Force, Low Voltage and High Flow Rate Electro-Thermal Micropump

    Directory of Open Access Journals (Sweden)

    Ghader Yosefi

    2014-12-01

    Full Text Available This paper presents the design and simulation of an improved electro-thermal micromachined pump for drug delivery applications. Thermal actuators, which are a type of Micro Electro Mechanical system (MEMS device, are highly useful because of their ability to deliver with great force and displacement. Thus, our structure is based on a thermal actuator that exploits the Joule heating effect and has been improved using the springy length properties of MEMS chevron beams. The Joule heating effect results in a difference in temperature and therefore displacement in the beams (actuators. Simulation results show that a maximum force of 4.4 mN and a maximum flow rate of 16 μL/min can be obtained by applying an AC voltage as low as 8 V at different frequencies ranging from 1 to 32 Hz. The maximum temperature was a problem at the chevron beams and the center shaft. Thus, to locally increase the temperature of the chevron beams alone and not that of the pumping diaphragm: (1 The air gaps 2 μm underneath and above the device layer were optimized for heat transfer. (2 Release holes and providing fins were created at the center shaft and actuator, respectively, to decrease the temperature by approximately 10 °C. (3 We inserted and used a polymer tube to serve as an insulator and eliminate leakage problems in the fluidic channel.

  9. Scaling Mesa Indium Phosphide DHBTs to Record Bandwidths

    Science.gov (United States)

    Lobisser, Evan

    Indium phosphide heterojunction bipolar transistors are able to achieve higher bandwidths at a given feature size than transistors in the Silicon material system for a given feature size. Indium phosphide bipolar transistors demonstrate higher breakdown voltages at a given bandwidth than both Si bipolars and field effect transistors in the InP material system. The high bandwidth of InP HBTs results from both intrinsic material parameters and bandgap engineering through epitaxial growth. The electron mobility in the InGaAs base and saturation velocity in the InP collector are both approximately three times higher than their counterparts in the SiGe material system. Resistance of the base can be made very low due to the large offset in the valence band between the InP emitter and the InGaAs base, which allows the base to be doped on the order of 1020 cm-3 with negligible reduction in emitter injection efficiency. This thesis deals with type-I, NPN dual-heterojunction bipolar transistors. The emitters are InP, and the base is InGaAs. There is a thin (˜ 10 nm) n-type InGaAs "setback" region, followed by a chirped superlattice InGaAs/InAlAs grade to the InP collector. The setback, grade, and collector are all lightly doped n-type. The emitter and collector are contacted through thin (˜ 5 nm) heavily doped n-type InGaAs layers to reduce contact resistivity. The primary focus of this work is increasing the bandwidth of InP HBTs through the proportional scaling of the device dimensions, both layer thicknesses and junction areas, as well as the reduction of the contact resistivities associated with the transistor. Essentially, all RC time constants and transit times must be reduced by a factor of two to double a transistor's bandwidth. Chapter 2 describes in detail the scaling laws and design principles for high frequency bipolar transistor design. A low-stress, blanket sputter deposited composite emitter metal process was developed. Refractory metal base contacts were

  10. Dynamic Bandwidth Allocation Algorithm with Fairness in 1G/10G Coexistence EPON System

    Science.gov (United States)

    Tanaka, Masaki; Takemoto, Michiya; Takahashi, Akira; Shimokasa, Kiyoshi

    Gigabit Ethernet Passive Optical Networks (GE-PON) systems have been deployed widely as a broadband access solution for the optical access network, the so-called FTTx networks. 10 Gigabit EPON (10G-EPON) is about to be standardizing by a task force (802.3av). To provide the next FTTx solution with 10G-EPON systems, one of the key technologies is how to migrate from 1G-based to 10G-based. In this paper, we present Dynamic Bandwidth Allocation (DBA) algorithm which considered a fair policy for 1G/10G coexistence EPON system to achieve a smooth migration.

  11. Bandwidth Dependence of Laser Plasma Instabilities Driven by the Nike KrF Laser

    Science.gov (United States)

    Weaver, J. L.; Oh, J.; Seely, J.; Kehne, D.; Brown, C. M.; Obenschain, S.; Serlin, V.; Schmitt, A. J.; Phillips, L.; Lehmberg, R. H.; McLean, E.; Manka, C.; Feldman, U.

    2011-10-01

    The Nike krypton-fluoride (KrF) laser at the Naval Research Laboratory operates in the deep UV (248 nm) and employs beam smoothing by induced spatial incoherence (ISI). In the first ISI studies at longer wavelengths (1054 nm and 527 nm) [Obenschain, PRL 62, 768(1989);Mostovych, PRL, 59, 1193(1987); Peyser, Phys. Fluids B 3, 1479(1991)], stimulated Raman scattering, stimulated Brillouin scattering, and the two plasmon decay instability were reduced when wide bandwidth ISI (δν / ν ~ 0.03-0.19%) pulses irradiated targets at moderate to high intensities (1014-1015W/cm2) . Recent Nike work showed that the threshold for quarter critical instabilities increased with the expected wavelength scaling, without accounting for the large bandwidth (δν ~ 1-3 THz). New experiments will compare laser plasma instabilities (LPI) driven by narrower bandwidth pulses to those observed with the standard operation. The bandwidth of KrF lasers can be reduced by adding narrow filters (etalons or gratings) in the initial stages of the laser. This talk will discuss the method used to narrow the output spectrum of Nike, the laser performance for this new operating mode, and target observations of LPI in planar CH targets. Work supported by DoE/NNSA.

  12. Note: Expanding the bandwidth of the ultra-low current amplifier using an artificial negative capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Kai, E-mail: kaixie@mail.xidian.edu.cn; Liu, Yan; Li, XiaoPing [School of Aerospace Science and Technology, Xidian University, Xi’an 710071 (China); Guo, Lixin [School of Physics and Optoelectronic Engineering, Xidian University, Xi’an 710071 (China); Zhang, Hanlu [School of Communication & Information Engineering, Xi’an University of Posts & Telecommunication, Xi’an 710121 (China)

    2016-04-15

    The bandwidth and low noise characteristics are often contradictory in ultra-low current amplifier, because an inevitable parasitic capacitance is paralleled with the high value feedback resistor. In order to expand the amplifier’s bandwidth, a novel approach was proposed by introducing an artificial negative capacitor to cancel the parasitic capacitance. The theory of the negative capacitance and the performance of the improved amplifier circuit with the negative capacitor are presented in this manuscript. The test was conducted by modifying an ultra-low current amplifier with a trans-impedance gain of 50 GΩ. The results show that the maximum bandwidth was expanded from 18.7 Hz to 3.3 kHz with more than 150 times of increase when the parasitic capacitance (∼0.17 pF) was cancelled. Meanwhile, the rise time decreased from 18.7 ms to 0.26 ms with no overshot. Any desired bandwidth or rise time within these ranges can be obtained by adjusting the ratio of cancellation of the parasitic and negative capacitance. This approach is especially suitable for the demand of rapid response to weak current, such as transient ion-beam detector, mass spectrometry analysis, and fast scanning microscope.

  13. The Effects of Drag and Tidal Forces on the Orbits of High-Velocity Clouds

    Science.gov (United States)

    Fernandes, Alexandre; Benjamin, R. A.

    2013-06-01

    Over the past several years, orbital constraints have been obtained for several high velocity cloud complexes surrounding the Milky Way: Complex GCP (Smith Cloud), Complex A, Complex H, Complex GCN, and the Magellanic Stream. We summarize what is known about the orbits of these clouds and and discuss how well each of these complexes fits a balistic trajectory, and discuss how the length of a complex across the sky is related to the inital "fragmentation" and velocity dispersion of the clouds. We then introduce gas drag into the simulation of the orbits of these complexes. We present analytical tests of our numerical method and characterize the departure of the clouds from the ballistic trajectory as a function of drag parameters (ambient gas density and velocity and cloud column density). Using the results of these simulations we comment on the survivability and ultimate fate of HVC in the context of the different models of drag forces.

  14. Trial of "Force and Motion Conceptual Evaluation" Tests in Japanese High Schools

    Science.gov (United States)

    Ryu, Junpei; Iwama, Toru; Yamazaki, Toshiaki; Ogawa, Masashi; Sakatani, Takafumi; Uchimura, Hiroshi; Taniguchi, Kazunari; Murata, Takatoshi

    A tentative version of Japanese translation of "Force and Motion Conceptual Evaluation" was used in a preliminary research to investigate high school students' conceptual understanding of Newtonian dynamics after the students attended formal courses on the topic in 2006-07. The results obtained were generally similar to those of post-tests after traditional lectures in universities in U.S.A.. It was also used as pre- and post-test at two extramural classes on dynamics based on the active learning materials. The results of those uses suggested a well validated version of the translated test and more systematic large scale research can contribute well to physics education research in Japan.

  15. High-speed atomic force microscopy reveals rotary catalysis of rotorless F₁-ATPase.

    Science.gov (United States)

    Uchihashi, Takayuki; Iino, Ryota; Ando, Toshio; Noji, Hiroyuki

    2011-08-05

    F(1) is an adenosine triphosphate (ATP)-driven motor in which three torque-generating β subunits in the α(3)β(3) stator ring sequentially undergo conformational changes upon ATP hydrolysis to rotate the central shaft γ unidirectionally. Although extensive experimental and theoretical work has been done, the structural basis of cooperative torque generation to realize the unidirectional rotation remains elusive. We used high-speed atomic force microscopy to show that the rotorless F(1) still "rotates"; in the isolated α(3)β(3) stator ring, the three β subunits cyclically propagate conformational states in the counterclockwise direction, similar to the rotary shaft rotation in F(1). The structural basis of unidirectionality is programmed in the stator ring. These findings have implications for cooperative interplay between subunits in other hexameric ATPases.

  16. Atomic force microscopy study of anion intercalation into highly oriented pyrolytic graphite

    Energy Technology Data Exchange (ETDEWEB)

    Alliata, D.; Haering, P.; Haas, O.; Koetz, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Siegenthaler, H. [University of Berne (Switzerland)

    1999-08-01

    In the context of ion transfer batteries, we studied highly oriented pyrolytic graphite (HOPG) in perchloric acid, as a model to elucidate the mechanism of electrochemical intercalation in graphite. Aim of the work is the local and time dependent investigation of dimensional changes of the host material during electrochemical intercalation processes on the nanometer scale. We used atomic force microscopy (AFM), combined with cyclic voltammetry, as in-situ tool of analysis during intercalation and expulsion of perchloric anions into the HOPG electrodes. According to the AFM measurements, the HOPG interlayer spacing increases by 32% when perchloric anions intercalate, in agreement with the formation of stage IV of graphite intercalation compounds. (author) 3 figs., 3 refs.

  17. Serum induced degradation of 3D DNA box origami observed by high speed atomic force microscope

    DEFF Research Database (Denmark)

    Jiang, Zaixing; Zhang, Shuai; Yang, Chuanxu;

    2015-01-01

    3D DNA origami holds tremendous potential to encapsulate and selectively release therapeutic drugs. Observations of real-time performance of 3D DNA origami structures in physiological environment will contribute much to its further applications. Here, we investigate the degradation kinetics of 3D...... DNA box origami in serum using high-speed atomic force microscope optimized for imaging 3D DNA origami in real time. The time resolution allows characterizing the stages of serum effects on individual 3D DNA box origami with nanometer resolution. Our results indicate that the whole digest process...... is a combination of a rapid collapse phase and a slow degradation phase. The damages of box origami mainly happen in the collapse phase. Thus, the structure stability of 3D DNA box origami should be further improved, especially in the collapse phase, before clinical applications...

  18. A serial-kinematic nanopositioner for high-speed atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wadikhaye, Sachin P., E-mail: sachin.wadikhaye@uon.edu.au; Yong, Yuen Kuan; Reza Moheimani, S. O. [School of Electrical Engineering and Computer Science, The University of Newcastle, Callaghan, NSW (Australia)

    2014-10-15

    A flexure-guided serial-kinematic XYZ nanopositioner for high-speed Atomic Force Microscopy is presented in this paper. Two aspects influencing the performance of serial-kinematic nanopositioners are studied in this work. First, mass reduction by using tapered flexures is proposed to increased the natural frequency of the nanopositioner. 25% increase in the natural frequency is achieved due to reduced mass with tapered flexures. Second, a study of possible sensor positioning in a serial-kinematic nanopositioner is presented. An arrangement of sensors for exact estimation of cross-coupling is incorporated in the proposed design. A feedforward control strategy based on phaser approach is presented to mitigate the dynamics and nonlinearity in the system. Limitations in design approach and control strategy are discussed in the Conclusion.

  19. Bandwidth Reduction and Convergence Analysis of Extremum Seeking Control with Feedback Encoding

    Directory of Open Access Journals (Sweden)

    Vikum Sri Wijesinghe

    2016-11-01

    Full Text Available Frequently a physical plant of a control system has an optimum operating point such as the spark (or injection time of an internal combustion engine that results in maximum torque. Extremum Seeking Control (ESC is a method of adaptive control capable of locating and maintaining a plant at such an optimum operating point in real time. It is capable of doing so with minimal a priori knowledge of the plant and can also track slowly varying changes. Input perturbed ESC schemes that use periodic dither signals have the disadvantage of requiring a high bandwidth for sampling and correlating the plant output with the dither signal. If the feedback path were to be implemented over a packet switched communication network, the high bandwidth requirement could result in increased congestion and consequently packet delays and dropouts. As a solution encoding using sporadic (aperiodic sampling techniques can be used in the feedback path of the ESC scheme to reduce the required bandwidth. However, in order to ensure convergence of the ESC scheme with encoding, the effect of the signal reconstruction error due to encoding on the critical correlation stage has to be investigated. The contribution of this paper is an investigation of the convergence requirements and bandwidth performance of two encoding schemes; Memory Based Event Triggering (MBET and Event Triggered Adaptive Differential Modulation (ETADM. The results show that MBET can fail for objective functions with plateaus. ETADM fails when the number of ETADM steps used for reconstructing the plant output per perturbation cycle are too low to allow correlation. In terms of bandwidth reduction MBET performs better than ETADM (97% and 70% respectively. However, the use of MBET results in a longer convergence time.

  20. Recombination and selectional forces in cyanopeptolin NRPS operons from highly similar, but geographically remote Planktothrix strains

    Directory of Open Access Journals (Sweden)

    Kristensen Tom

    2008-08-01

    Full Text Available Abstract Background Cyanopeptolins are nonribosomally produced heptapetides showing a highly variable composition. The cyanopeptolin synthetase operon has previously been investigated in three strains from the genera Microcystis, Planktothrix and Anabaena. Cyanopeptolins are displaying protease inhibitor activity, but the biological function(s is (are unknown. Cyanopeptolin gene cluster variability and biological functions of the peptide variants are likely to be interconnected. Results We have investigated two cyanopeptolin gene clusters from highly similar, but geographically remote strains of the same genus. Sequencing of a nonribosomal peptide synthetase (NRPS cyanopeptolin gene cluster from the Japanese strain Planktothrix NIES 205 (205-oci, showed the 30 kb gene cluster to be highly similar to the oci gene cluster previously described in Planktothrix NIVA CYA 116, isolated in Norway. Both operons contained seven NRPS modules, a sulfotransferase (S and a glyceric acid loading (GA-domain. Sequence analyses showed a high degree of conservation, except for the presence of an epimerase domain in NIES 205 and the regions around the epimerase, showing high substitution rates and Ka/Ks values above 1. The two strains produce almost identical cyanopeptolins, cyanopeptolin-1138 and oscillapeptin E respectively, but with slight differences regarding the production of minor cyanopeptolin variants. These variants may be the result of relaxed adenylation (A-domain specificity in the nonribosomal enzyme complex. Other genetic markers (16S rRNA, ntcA and the phycocyanin cpcBA spacer were identical, supporting that these geographically separated Planktothrix strains are closely related. Conclusion A horizontal gene transfer event resulting in exchange of a whole module-encoding region was observed. Nucleotide statistics indicate that both purifying selection and positive selection forces are operating on the gene cluster. The positive selection forces are

  1. Measurement of repulsive force of high Tc materials due to Meissner effect and its two dimensional distribution

    Science.gov (United States)

    Ishigaki, H.; Itoh, M.; Hida, A.; Endo, H.; Oya, T.

    1991-03-01

    As a basic study for magnetic bearings using high-Tc superconductors, evaluations of the materials were conducted. These evaluations included measurements of the repulsive force and lateral restoring force of various kinds of YBCO pellets. Pure air, which was supplied in the process of fabrication, and the presence of Ag in YBCO showed evidence of the effects of increasing the repulsive force. The lateral restoring force which was observed in the lateral displacement of a levitated permanent magnet over YBCO pellets was also affected by pure air and the presence of Ag. A new measuring instrument for magnetic fields was developed by using a highly sensitive force sensor. Because this instrument has the capability of measuring the repulsive force due to the Meissner effect, it was used for evaluating the two-dimensional distribution of superconducting properties. Results show that the pellets had nonuniform superconducting properties. The two-dimensional distribution of residual flux density on the pellets which had been cooled in a magnetic field (field cooling) was also observed by means of the instrument. The mechanism for generating lateral force is discussed in relation to the distribution.

  2. High-density force myography: A possible alternative for upper-limb prosthetic control

    Directory of Open Access Journals (Sweden)

    Ashkan Radmand, PhD

    2016-07-01

    Full Text Available Several multiple degree-of-freedom upper-limb prostheses that have the promise of highly dexterous control have recently been developed. Inadequate controllability, however, has limited adoption of these devices. Introducing more robust control methods will likely result in higher acceptance rates. This work investigates the suitability of using high-density force myography (HD-FMG for prosthetic control. HD-FMG uses a high-density array of pressure sensors to detect changes in the pressure patterns between the residual limb and socket caused by the contraction of the forearm muscles. In this work, HD-FMG outperforms the standard electromyography (EMG-based system in detecting different wrist and hand gestures. With the arm in a fixed, static position, eight hand and wrist motions were classified with 0.33% error using the HD-FMG technique. Comparatively, classification errors in the range of 2.2%–11.3% have been reported in the literature for multichannel EMG-based approaches. As with EMG, position variation in HD-FMG can introduce classification error, but incorporating position variation into the training protocol reduces this effect. Channel reduction was also applied to the HD-FMG technique to decrease the dimensionality of the problem as well as the size of the sensorized area. We found that with informed, symmetric channel reduction, classification error could be decreased to 0.02%.

  3. Evaluation of cutting force and surface roughness in high-speed milling of compacted graphite iron

    Directory of Open Access Journals (Sweden)

    Azlan Suhaimi Mohd

    2017-01-01

    Full Text Available Compacted Graphite Iron, (CGI is known to have outstanding mechanical strength and weight-to-strength ratio as compared to conventional grey cast iron, (CI. The outstanding characteristics of CGI is due to its graphite particle shape, which is presented as compacted vermicular particle. The graphite is interconnected with random orientation and round edges, which results in higher mechanical strength. Whereas, graphite in the CI consists of a smooth-surfaced flakes that easily propagates cracks which results in weaker and brittle properties as compared to CGI. Owing to its improved properties, CGI is considered as the best candidate material in substituting grey cast iron that has been used in engine block applications for years. However, the smooth implementation of replacing CI with CGI has been hindered due to the poor machinability of CGI especially at high cutting speed. The tool life is decreased by 20 times when comparing CGI with CI under the same cutting condition. This study investigates the effect of using cryogenic cooling and minimum quantity lubrication (MQL during high-speed milling of CGI (grade 450. Results showed that, the combination of internal cryogenic cooling and enhanced MQL improved the tool life, cutting force and surface quality as compared to the conventional flood coolant strategy during high-speed milling of CGI.

  4. Adaptive control of force microscope cantilever dynamics

    Science.gov (United States)

    Jensen, S. E.; Dougherty, W. M.; Garbini, J. L.; Sidles, J. A.

    2007-09-01

    Magnetic resonance force microscopy (MRFM) and other emerging scanning probe microscopies entail the detection of attonewton-scale forces. Requisite force sensitivities are achieved through the use of soft force microscope cantilevers as high resonant-Q micromechanical oscillators. In practice, the dynamics of these oscillators are greatly improved by the application of force feedback control computed in real time by a digital signal processor (DSP). Improvements include increased sensitive bandwidth, reduced oscillator ring up/down time, and reduced cantilever thermal vibration amplitude. However, when the cantilever tip and the sample are in close proximity, electrostatic and Casimir tip-sample force gradients can significantly alter the cantilever resonance frequency, foiling fixed-gain narrow-band control schemes. We report an improved, adaptive control algorithm that uses a Hilbert transform technique to continuously measure the vibration frequency of the thermally-excited cantilever and seamlessly adjust the DSP program coefficients. The closed-loop vibration amplitude is typically 0.05 nm. This adaptive algorithm enables narrow-band formally-optimal control over a wide range of resonance frequencies, and preserves the thermally-limited signal to noise ratio (SNR).

  5. Constant-bandwidth constant-temperature hot-wire anemometer.

    Science.gov (United States)

    Ligeza, P

    2007-07-01

    A constant-temperature anemometer (CTA) enables the measurement of fast-changing velocity fluctuations. In the classical solution of CTA, the transmission band is a function of flow velocity. This is a minor drawback when the mean flow velocity does not significantly change, though it might lead to dynamic errors when flow velocity varies over a considerable range. A modification is outlined, whereby an adaptive controller is incorporated in the CTA system such that the anemometer's transmission band remains constant in the function of flow velocity. For that purpose, a second feedback loop is provided, and the output signal from the anemometer will regulate the controller's parameters such that the transmission bandwidth remains constant. The mathematical model of a CTA that has been developed and model testing data allow a through evaluation of the proposed solution. A modified anemometer can be used in measurements of high-frequency variable flows in a wide range of velocities. The proposed modification allows the minimization of dynamic measurement errors.

  6. Bandwidth control of wavelength-selective uncooled infrared sensors using two-dimensional plasmonic absorbers

    Science.gov (United States)

    Ogawa, Shinpei; Fujisawa, Daisuke; Kimata, Masafumi

    2016-05-01

    Although standard uncooled infrared (IR) sensors can be used to record information such as the shape, position, and average radiant intensity of objects, these devices cannot capture color (that is, wavelength) data. Achieving wavelength selectivity would pave the way for the development of advanced uncooled IR sensors capable of providing color information as well as multi-color image sensors that would have significant advantages in applications such as fire detection, gas analysis, hazardous material recognition, and biological analysis. We have previously demonstrated an uncooled IR sensor incorporating a two-dimensional plasmonic absorber (2D PLA) that exhibits wavelength selectivity over a wide range in the mid- and long-IR regions. This PLA has a 2D Au-based periodic array of dimples, in which surface plasmon modes are induced and wavelength-selective absorption occurs. However, the dependence of the absorption bandwidth on certain structural parameters has yet to be clarified. The bandwidth of such devices is a vital factor when considering the practical application of these sensors to tasks such as gas detection. In the present study, control of the bandwidth was theoretically investigated using a rigorous coupled wave analysis approach. It is demonstrated that the dimple sidewall structure has a significant impact on the bandwidth and can be used to control both narrow- and broadband absorption. Increasing the sidewall slope was found to decrease the bandwidth due to suppression of cavity-mode resonance in the depth direction of the dimples. These results will contribute to the development of high-resolution, wavelength-selective uncooled IR sensors.

  7. Gold-decorated highly ordered self-organized grating-like nanostructures on Ge surface: Kelvin probe force microscopy and conductive atomic force microscopy studies

    Science.gov (United States)

    Alam Mollick, Safiul; Kumar, Mohit; Singh, Ranveer; Satpati, Biswarup; Ghose, Debabrata; Som, Tapobrata

    2016-10-01

    Nanoarchitecture by atomic manipulation is considered to be one of the emerging trends in advanced functional materials. It has a gamut of applications to offer in nanoelectronics, chemical sensing, and nanobiological science. In particular, highly ordered one-dimensional semiconductor nanostructures fabricated by self-organization methods are in high demand for their high aspect ratios and large number of applications. An efficient way of fabricating semiconductor nanostructures is by molecular beam epitaxy, where atoms are added to a crystalline surface at an elevated temperature during growth, yielding the desired structures in a self-assembled manner. In this article, we offer a room temperature process, in which atoms are sputtered away by ion impacts. Using gold ion implantation, the present study reports on the formation of highly ordered self-organized long grating-like nanostructures, with grooves between them, on a germanium surface. The ridges of the patterns are shown to have flower-like protruding nanostructures, which are mostly decorated by gold atoms. By employing local probe microscopic techniques like Kelvin probe force microscopy and conductive atomic force microscopy, we observe a spatial variation in the work function and different nanoscale electrical conductivity on the ridges of the patterns and the grooves between them, which can be attributed to gold atom decorated ridges. Thus, the architecture presented offers the advantage of using the patterned germanium substrates as periodic arrays of conducting ridges and poorly conducting grooves between them.

  8. Task III: Development of an Effective Computational Methodology for Body Force Representation of High-speed Rotor 37

    Science.gov (United States)

    Tan, Choon-Sooi; Suder, Kenneth (Technical Monitor)

    2003-01-01

    A framework for an effective computational methodology for characterizing the stability and the impact of distortion in high-speed multi-stage compressor is being developed. The methodology consists of using a few isolated-blade row Navier-Stokes solutions for each blade row to construct a body force database. The purpose of the body force database is to replace each blade row in a multi-stage compressor by a body force distribution to produce same pressure rise and flow turning. To do this, each body force database is generated in such a way that it can respond to the changes in local flow conditions. Once the database is generated, no hrther Navier-Stokes computations are necessary. The process is repeated for every blade row in the multi-stage compressor. The body forces are then embedded as source terms in an Euler solver. The method is developed to have the capability to compute the performance in a flow that has radial as well as circumferential non-uniformity with a length scale larger than a blade pitch; thus it can potentially be used to characterize the stability of a compressor under design. It is these two latter features as well as the accompanying procedure to obtain the body force representation that distinguish the present methodology from the streamline curvature method. The overall computational procedures have been developed. A dimensional analysis was carried out to determine the local flow conditions for parameterizing the magnitudes of the local body force representation of blade rows. An Euler solver was modified to embed the body forces as source terms. The results from the dimensional analysis show that the body forces can be parameterized in terms of the two relative flow angles, the relative Mach number, and the Reynolds number. For flow in a high-speed transonic blade row, they can be parameterized in terms of the local relative Mach number alone.

  9. High-multipolar effects on the Casimir force: the non-retarded limit

    CERN Document Server

    Noguez, C; Esquivel-Sirvent, R; Villarreal, C; Noguez, Cecilia; Roman-Velazquez, Carlos E.; Esquivel-Sirvent, Raul; Villarreal, Carlos

    2003-01-01

    We calculate exactly the Casimir force or dispersive force, in the non-retarded limit, between a spherical nanoparticle and a substrate beyond the London's or dipolar approximation. We find that the force is a non-monotonic function of the distance between the sphere and the substrate, such that, it is enhanced by several orders of magnitude as the sphere approaches the substrate. Our results do not agree with previous predictions like the Proximity theorem approach.

  10. Effective bandwidth guaranteed routing schemes for MPLS traffic engineering

    Science.gov (United States)

    Wang, Bin; Jain, Nidhi

    2001-07-01

    In this work, we present online algorithms for dynamic routing bandwidth guaranteed label switched paths (LSPs) where LSP set-up requests (in terms of a pair of ingress and egress routers as well as its bandwidth requirement) arrive one by one and there is no a priori knowledge regarding future LSP set-up requests. In addition, we consider rerouting of LSPs in this work. Rerouting of LSPs has not been well studied in previous work on LSP routing. The need of LSP rerouting arises in a number of ways: occurrence of faults (link and/or node failures), re-optimization of existing LSPs' routes to accommodate traffic fluctuation, requests with higher priorities, and so on. We formulate the bandwidth guaranteed LSP routing with rerouting capability as a multi-commodity flow problem. The solution to this problem is used as the benchmark for comparing other computationally less costly algorithms studied in this paper. Furthermore, to more efficiently utilize the network resources, we propose online routing algorithms which route bandwidth demands over multiple paths at the ingress router to satisfy the customer requests while providing better service survivability. Traffic splitting and distribution over the multiple paths are carefully handled using table-based hashing schemes while the order of packets within a flow is preserved. Preliminary simulations are conducted to show the performance of different design choices and the effectiveness of the rerouting and multi-path routing algorithms in terms of LSP set-up request rejection probability and bandwidth blocking probability.

  11. Open-Loop Wide-Bandwidth Phase Modulation Techniques

    Directory of Open Access Journals (Sweden)

    Nitin Nidhi

    2011-01-01

    Full Text Available The ever-increasing growth in the bandwidth of wireless communication channels requires the transmitter to be wide-bandwidth and power-efficient. Polar and outphasing transmitter topologies are two promising candidates for such applications, in future. Both these architectures require a wide-bandwidth phase modulator. Open-loop phase modulation presents a viable solution for achieving wide-bandwidth operation. An overview of prior art and recent approaches for phase modulation is presented in this paper. Phase quantization noise cancellation was recently introduced to lower the out-of-band noise in a digital phase modulator. A detailed analysis on the impact of timing and quantization of the cancellation signal is presented. Noise generated by the transmitter in the receive band frequency poses another challenge for wide-bandwidth transmitter design. Addition of a noise transfer function notch, in a digital phase modulator, to reduce the noise in the receive band during phase modulation is described in this paper.

  12. Control Parametric Analysis on Improving Park Restoring Force Model and Damage Evaluation of High-Strength Structure

    Directory of Open Access Journals (Sweden)

    Huang-bin Lin

    2016-01-01

    Full Text Available In the dynamic time-history analysis of structural elastoplasticity, it is important to develop a universal mathematical model that can describe the force-displacement characteristics for restoring force. By defining three control parameters (stiffness degradation, slip closure γ, energy degradation β, the Park restoring force mathematical model can simulate various components. In this study, the Park restoring force has been improved by adding two control parameters (energy-based strength degradation βe and ductility-based strength degradation βd. Based on the testing data, the constitutive model is input and 55 numerical models are developed to analyze the effects of various parameters on structural behavior. Conclusion. (1 β has determinative effect on structural behavior; the effect of βe is basically consistent with that of β; α has significant effect on shear forces and bending moments; γ has significant effect on displacements and accelerations; βd has significant effect on shearing forces, acceleration, and total energy consumptions. (2 Based on the classification of four types of damage level, the recommended values for α, γ, β, βe, and βd are presented. (3 Based on the testing data of high-strength columns, the recommended values for the five control parameters of the improved Park restoring force model are presented.

  13. High-speed atomic force microscopy for large scan sizes using small cantilevers

    Science.gov (United States)

    Braunsmann, Christoph; Schäffer, Tilman E.

    2010-06-01

    We present a high-speed atomic force microscope that exhibits a number of practical advantages over previous designs. Its central component is a high-speed scanner with a maximum scan size of 23 µm × 23 µm and a conveniently large sample stage area (6.5 mm × 6.5 mm). In combination with small cantilevers, image rates of up to 46 images s - 1 in air and 13 images s - 1 in liquid are reached under z-feedback control. By large scan size imaging of collagen fibrils in air, sample velocities of 8.8 mm s - 1 in the xy-direction and 11 mm s - 1 in the z-direction are reached. To provide optimized imaging conditions for both large and small scan sizes, a modular scanner design allows easily exchanging the x- and y-piezos. The scanner is therefore also suited for investigations on the molecular and atomic scale, which is demonstrated by imaging the step dynamics of a calcite surface during dissolution and the hexagonal lattice of a mica surface in liquid.

  14. Study on a high thrust force bi-double-sided permanent magnet linear synchronous motor

    Directory of Open Access Journals (Sweden)

    Liang Tong

    2016-03-01

    Full Text Available A high thrust force bi-double-sided permanent magnet linear synchronous motor used in gantry-type five-axis machining center is designed and its performance was tested in this article. This motor is the subproject of Chinese National Science and Technology Major Project named as “development of domestic large thrust linear motor used in high-speed gantry-type five-axis machining center project” jointly participated by enterprises and universities. According to the requirement of the application environment and motor performance parameters, the linear motor’s basic dimensions, form of windings, and magnet arrangement are preliminarily specified through theoretical analysis and calculation. To verify the correctness of the result of the calculation, the finite element model of the motor is established. The static and dynamic characteristics of the motor are studied and analyzed through the finite element method, and the initial scheme is revised. The prototype of the motor is manufactured based on the final revised structure parameters, and the performance of the motor is fully tested using the evaluation platform for direct-drive motor component. Experimental test results meet the design requirements and show the effectiveness of design method and process.

  15. High-speed atomic force microscopy reveals structural dynamics of amyloid β1-42 aggregates.

    Science.gov (United States)

    Watanabe-Nakayama, Takahiro; Ono, Kenjiro; Itami, Masahiro; Takahashi, Ryoichi; Teplow, David B; Yamada, Masahito

    2016-05-24

    Aggregation of amyloidogenic proteins into insoluble amyloid fibrils is implicated in various neurodegenerative diseases. This process involves protein assembly into oligomeric intermediates and fibrils with highly polymorphic molecular structures. These structural differences may be responsible for different disease presentations. For this reason, elucidation of the structural features and assembly kinetics of amyloidogenic proteins has been an area of intense study. We report here the results of high-speed atomic force microscopy (HS-AFM) studies of fibril formation and elongation by the 42-residue form of the amyloid β-protein (Aβ1-42), a key pathogenetic agent of Alzheimer's disease. Our data demonstrate two different growth modes of Aβ1-42, one producing straight fibrils and the other producing spiral fibrils. Each mode depends on initial fibril nucleus structure, but switching from one growth mode to another was occasionally observed, suggesting that fibril end structure fluctuated between the two growth modes. This switching phenomenon was affected by buffer salt composition. Our findings indicate that polymorphism in fibril structure can occur after fibril nucleation and is affected by relatively modest changes in environmental conditions.

  16. Cantilevered bimorph-based scanner for high speed atomic force microscopy with large scanning range.

    Science.gov (United States)

    Zhou, Yusheng; Shang, Guangyi; Cai, Wei; Yao, Jun-en

    2010-05-01

    A cantilevered bimorph-based resonance-mode scanner for high speed atomic force microscope (AFM) imaging is presented. The free end of the bimorph is used for mounting a sample stage and the other one of that is fixed on the top of a conventional single tube scanner. High speed scanning is realized with the bimorph-based scanner vibrating at resonant frequency driven by a sine wave voltage applied to one piezolayer of the bimorph, while slow scanning is performed by the tube scanner. The other piezolayer provides information on vibration amplitude and phase of the bimorph itself simultaneously, which is used for real-time data processing and image calibration. By adjusting the free length of the bimorph, the line scan rate can be preset ranging from several hundred hertz to several kilohertz, which would be beneficial for the observation of samples with different properties. Combined with a home-made AFM system and a commercially available data acquisition card, AFM images of various samples have been obtained, and as an example, images of the silicon grating taken at a line rate of 1.5 kHz with the scan size of 20 microm are given. By manually moving the sample of polished Al foil surface while scanning, the capability of dynamic imaging is demonstrated.

  17. Acoustic radiation force impulse (ARFI) imaging of zebrafish embryo by high-frequency coded excitation sequence.

    Science.gov (United States)

    Park, Jinhyoung; Lee, Jungwoo; Lau, Sien Ting; Lee, Changyang; Huang, Ying; Lien, Ching-Ling; Kirk Shung, K

    2012-04-01

    Acoustic radiation force impulse (ARFI) imaging has been developed as a non-invasive method for quantitative illustration of tissue stiffness or displacement. Conventional ARFI imaging (2-10 MHz) has been implemented in commercial scanners for illustrating elastic properties of several organs. The image resolution, however, is too coarse to study mechanical properties of micro-sized objects such as cells. This article thus presents a high-frequency coded excitation ARFI technique, with the ultimate goal of displaying elastic characteristics of cellular structures. Tissue mimicking phantoms and zebrafish embryos are imaged with a 100-MHz lithium niobate (LiNbO₃) transducer, by cross-correlating tracked RF echoes with the reference. The phantom results show that the contrast of ARFI image (14 dB) with coded excitation is better than that of the conventional ARFI image (9 dB). The depths of penetration are 2.6 and 2.2 mm, respectively. The stiffness data of the zebrafish demonstrate that the envelope is harder than the embryo region. The temporal displacement change at the embryo and the chorion is as large as 36 and 3.6 μm. Consequently, this high-frequency ARFI approach may serve as a remote palpation imaging tool that reveals viscoelastic properties of small biological samples.

  18. High bandwidth on-chip capacitive tuning of microtoroid resonators

    CERN Document Server

    Baker, Christopher G; McAuslan, David L; Sheridan, Eoin; Bowen, Warwick P

    2016-01-01

    We report on the design, fabrication and characterization of silica microtoroid based cavity opto-electromechanical systems (COEMS). Electrodes patterned onto the microtoroid resonators allow for rapid capacitive tuning of the optical whispering gallery mode resonances while maintaining their ultrahigh quality factor, enabling applications such as efficient radio to optical frequency conversion, optical routing and switching applications.

  19. High bandwidth synaptic communication and frequency tracking in human neocortex

    NARCIS (Netherlands)

    Testa-Silva, Guilherme; Verhoog, Matthijs B; Linaro, Daniele; de Kock, Christiaan P J; Baayen, Johannes C; Meredith, Rhiannon M; De Zeeuw, Chris I; Giugliano, Michele; Mansvelder, Huibert D

    2014-01-01

    Neuronal firing, synaptic transmission, and its plasticity form the building blocks for processing and storage of information in the brain. It is unknown whether adult human synapses are more efficient in transferring information between neurons than rodent synapses. To test this, we recorded from c

  20. Wide bandwidth high efficiency power converter for rf amplifiers

    OpenAIRE

    Vasic, Miroslav

    2011-01-01

    Tradicionalmente, en el mundo de la amplificación de potencia de alta frecuencia, se han distinguido dos grandes familias de amplificadores de potencia, atendiendo al efecto de su utilización sobre las señales amplificadas por los mismos: lineales y no lineales. Los amplificadores lineales se han relacionado con las clases de amplificación A, B y AB generalmente poco eficaces en el aprovechamiento de la energía, mientras que los amplificadores no lineales se han asociado a clases de funcionam...

  1. Design of application specific high bandwidth Nyquist DAC

    NARCIS (Netherlands)

    Zhijun, Wei

    2008-01-01

    Digital-to-analog (DAC) converters translate digital codes into different physical quantities in voltage, current or charges. They are used either as a stand alone functional block in a big system or as a subsystem in analog-to-digital (ADC) converters. The DAC in this project is a subsystem in a tw

  2. High speed, real-time, camera bandwidth converter

    Science.gov (United States)

    Bower, Dan E; Bloom, David A; Curry, James R

    2014-10-21

    Image data from a CMOS sensor with 10 bit resolution is reformatted in real time to allow the data to stream through communications equipment that is designed to transport data with 8 bit resolution. The incoming image data has 10 bit resolution. The communication equipment can transport image data with 8 bit resolution. Image data with 10 bit resolution is transmitted in real-time, without a frame delay, through the communication equipment by reformatting the image data.

  3. Investigation of polymer derived ceramics cantilevers for application of high speed atomic force microscopy

    Science.gov (United States)

    Wu, Chia-Yun

    High speed Atomic Force Microscopy (AFM) has a wide variety of applications ranging from nanomanufacturing to biophysics. In order to have higher scanning speed of certain AFM modes, high resonant frequency cantilevers are needed; therefore, the goal of this research is to investigate using polymer derived ceramics for possible applications in making high resonant frequency AFM cantilevers using complex cross sections. The polymer derived ceramic that will be studied, is silicon carbide. Polymer derived ceramics offer a potentially more economic fabrication approach for MEMS due to their relatively low processing temperatures and ease of complex shape design. Photolithography was used to make the desired cantilever shapes with micron scale size followed by a wet etching process to release the cantilevers from the substrates. The whole manufacturing process we use borrow well-developed techniques from the semiconducting industry, and as such this project also could offer the opportunity to reduce the fabrication cost of AFM cantilevers and MEMS in general. The characteristics of silicon carbide made from the precursor polymer, SMP-10 (Starfire Systems), were studied. In order to produce high qualities of silicon carbide cantilevers, where the major concern is defects, proper process parameters needed to be determined. Films of polymer derived ceramics often have defects due to shrinkage during the conversion process. Thus control of defects was a central issue in this study. A second, related concern was preventing oxidation; the polymer derived ceramics we chose is easily oxidized during processing. Establishing an environment without oxygen in the whole process was a significant challenge in the project. The optimization of the parameters for using photolithography and wet etching process was the final and central goal of the project; well established techniques used in microfabrication were modified for use in making the cantilever in the project. The techniques

  4. Synchronous fire activity in the tropical high Andes: an indication of regional climate forcing.

    Science.gov (United States)

    Román-Cuesta, R M; Carmona-Moreno, C; Lizcano, G; New, M; Silman, M; Knoke, T; Malhi, Y; Oliveras, I; Asbjornsen, H; Vuille, M

    2014-06-01

    Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (>2000 masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982-2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño- Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build-up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high-frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire-peak seasons (t-1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build

  5. Modulated method for efficient, narrow-bandwidth, laser Compton X-ray and gamma-ray sources

    Energy Technology Data Exchange (ETDEWEB)

    Barty, Christopher P. J.

    2017-07-11

    A method of x-ray and gamma-ray generation via laser Compton scattering uses the interaction of a specially-formatted, highly modulated, long duration, laser pulse with a high-frequency train of high-brightness electron bunches to both create narrow bandwidth x-ray and gamma-ray sources and significantly increase the laser to Compton photon conversion efficiency.

  6. Nuclear forces and the properties of matter at high temperature and density

    Energy Technology Data Exchange (ETDEWEB)

    Rayet, M.; Arnould, M.; Paulus, G.; Tondeur, F.

    1982-12-01

    We present two Skyrme-type forces which are particularly well suited for the description of presupernova core or matter in nascent neutron star. They are compared to other forces currently used in this field, with regard to finite nuclei and infinite matter properties, and to the coexistence of nuclei in a hot and dense nucleon gas.

  7. Cascaded passive silicon microrings for large bandwidth slow light device

    Energy Technology Data Exchange (ETDEWEB)

    Li Yuntao; Hu Yingtao; Xiao Xi; Li Zhiyong; Yu Yude; Yu Jinzhong, E-mail: ytli@semi.ac.cn [State Key Laboratory of integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083 (China)

    2011-02-01

    Slow light devices have important applications in the areas of data buffering, signal processing, and phased array antenna. Cascaded microring resonators structure can obtain large delay and also enhance the bandwidth, which was considered as a potential approach for future on-chip optical buffer. In this paper, we demonstrated a large bandwidth slow light device using cascaded Silicon-on-insulator (SOI) based microring resonators. With carefully designed the gap between the bus and the ring waveguides and the distances between the adjacent rings, a 57 ps group delay was observed and 83 Gbps maximum allowable bit rate is suggested according the measured 3 dB spectral bandwidth in the 8-stage cascaded microrings.

  8. Correlation and image compression for limited-bandwidth CCD.

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Douglas G.

    2005-07-01

    As radars move to Unmanned Aerial Vehicles with limited-bandwidth data downlinks, the amount of data stored and transmitted with each image becomes more significant. This document gives the results of a study to determine the effect of lossy compression in the image magnitude and phase on Coherent Change Detection (CCD). We examine 44 lossy compression types, plus lossless zlib compression, and test each compression method with over 600 CCD image pairs. We also derive theoretical predictions for the correlation for most of these compression schemes, which compare favorably with the experimental results. We recommend image transmission formats for limited-bandwidth programs having various requirements for CCD, including programs which cannot allow performance degradation and those which have stricter bandwidth requirements at the expense of CCD performance.

  9. Bandwidth Extension of Speech Signals: A Comprehensive Review

    Directory of Open Access Journals (Sweden)

    N.Prasad

    2016-02-01

    Full Text Available Telephone systems commonly transmit narrowband (NB speech with an audio bandwidth limited to the traditional telephone band of 300-3400 Hz. To improve the quality and intelligibility of speech degraded by narrow bandwidth, researchers have tried to standardize the telephonic networks by introducing wideband (50-7000 Hz speech codecs. Wideband (WB speech transmission requires the transmission network and terminal devices at both ends to be upgraded to the wideband that turns out to be time-consuming. In this situation, novel Bandwidth extension (BWE techniques have been developed to overcome the limitations of NB speech. This paper discusses the basic principles, realization, and applications of BWE. Challenges and limitations of BWE are also addressed.

  10. Performance Investigation of Virtual Private Networks with Different Bandwidth Allocations

    Directory of Open Access Journals (Sweden)

    Ramaswamy Muthiah

    2010-01-01

    Full Text Available A Virtual Private Network (VPN provides private network connections over a publicly accessible shared network. The effective allocation of bandwidth for VPNs assumes significance in the present scenario due to varied traffic. Each VPN endpoint specifies bounds on the total amount of traffic that it is likely to send or receive at any time. The network provider tailors the VPN so that there is sufficient bandwidth for any traffic matrix that is consistent with these bounds. The approach incorporates the use of Ad-hoc On demand Distance Vector (AODV protocol, with a view to accomplish an enhancement in the performance of the mobile networks. The NS2 based simulation results are evaluated in terms of its metrics for different bandwidth allocations, besides analyzing its performance in the event of exigencies such as link failures. The results highlight the suitability of the proposed strategy in the context of real time applications.

  11. PRIORITY BASED BANDWIDTH ALLOCATION IN WIRELESS SENSOR NETWORKS

    Directory of Open Access Journals (Sweden)

    Mary Cherian

    2014-12-01

    Full Text Available Most of the sensor network applications need real time communication and the need for deadline aware real time communication is becoming eminent in these applications. These applications have different dead line requirements also. The real time applications of wireless sensor networks are bandwidth sensitive and need higher share of bandwidth for higher priority data to meet the dead line requirements. In this paper we focus on the MAC layer modifications to meet the real time requirements of different priority data. Bandwidth partitioning among different priority transmissions is implemented through MAC layer modifications. The MAC layer implements a queuing model that supports lower transfer rate for lower priority packets and higher transfer rate for real time packets with higher priority, minimizing the end to end delay. The performance of the algorithm is evaluated with varying node distribution.

  12. Analysis of bandwidth measurement methodologies over WLAN systems

    CERN Document Server

    Portoles-Comeras, Marc; Mangues-Bafalluy, Josep; Domingo-Pascual, Jordi

    2009-01-01

    WLAN devices have become a fundamental component of nowadays network deployments. However, even though traditional networking applications run mostly unchanged over wireless links, the actual interaction between these applications and the dynamics of wireless transmissions is not yet fully understood. An important example of such applications are bandwidth estimation tools. This area has become a mature research topic with well-developed results. Unfortunately recent studies have shown that the application of these results to WLAN links is not straightforward. The main reasons for this is that the assumptions taken to develop bandwidth measurements tools do not hold any longer in the presence of wireless links (e.g. non-FIFO scheduling). This paper builds from these observations and its main goal is to analyze the interaction between probe packets and WLAN transmissions in bandwidth estimation processes. The paper proposes an analytical model that better accounts for the particularities of WLAN links. The mod...

  13. Adaptive broadcasting mechanism for bandwidth allocation in mobile services.

    Science.gov (United States)

    Horng, Gwo-Jiun; Wang, Chi-Hsuan; Chou, Chih-Lun

    2014-01-01

    This paper proposes a tree-based adaptive broadcasting (TAB) algorithm for data dissemination to improve data access efficiency. The proposed TAB algorithm first constructs a broadcast tree to determine the broadcast frequency of each data and splits the broadcast tree into some broadcast wood to generate the broadcast program. In addition, this paper develops an analytical model to derive the mean access latency of the generated broadcast program. In light of the derived results, both the index channel's bandwidth and the data channel's bandwidth can be optimally allocated to maximize bandwidth utilization. This paper presents experiments to help evaluate the effectiveness of the proposed strategy. From the experimental results, it can be seen that the proposed mechanism is feasible in practice.

  14. A novel dynamic wavelength bandwidth allocation scheme over OFDMA PONs

    Science.gov (United States)

    Yan, Bo; Guo, Wei; Jin, Yaohui; Hu, Weisheng

    2011-12-01

    With rapid growth of Internet applications, supporting differentiated service and enlarging system capacity have been new tasks for next generation access system. In recent years, research in OFDMA Passive Optical Networks (PON) has experienced extraordinary development as for its large capacity and flexibility in scheduling. Although much work has been done to solve hardware layer obstacles for OFDMA PON, scheduling algorithm on OFDMA PON system is still under primary discussion. In order to support QoS service on OFDMA PON system, a novel dynamic wavelength bandwidth allocation (DWBA) algorithm is proposed in this paper. Per-stream QoS service is supported in this algorithm. Through simulation, we proved our bandwidth allocation algorithm performs better in bandwidth utilization and differentiate service support.

  15. Maximum bandwidth snapshot channeled imaging polarimeter with polarization gratings

    Science.gov (United States)

    LaCasse, Charles F.; Redman, Brian J.; Kudenov, Michael W.; Craven, Julia M.

    2016-05-01

    Compact snapshot imaging polarimeters have been demonstrated in literature to provide Stokes parameter estimations for spatially varying scenes using polarization gratings. However, the demonstrated system does not employ aggressive modulation frequencies to take full advantage of the bandwidth available to the focal plane array. A snapshot imaging Stokes polarimeter is described and demonstrated through results. The simulation studies the challenges of using a maximum bandwidth configuration for a snapshot polarization grating based polarimeter, such as the fringe contrast attenuation that results from higher modulation frequencies. Similar simulation results are generated and compared for a microgrid polarimeter. Microgrid polarimeters are instruments where pixelated polarizers are superimposed onto a focal plan array, and this is another type of spatially modulated polarimeter, and the most common design uses a 2x2 super pixel of polarizers which maximally uses the available bandwidth of the focal plane array.

  16. A method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed presses

    Institute of Scientific and Technical Information of China (English)

    Jim Wang; Sheng-dun Zhao; Hu-shan Shi; Chun-jian Hua

    2009-01-01

    A new method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed mechanical presses was put forward. By analyzing the kinematic characteristics of a center-located slider-crank mechanism whose crank rotates at a constant angular velocity, the kinematic parameters of the slide, connecting rod and crank were formulated approximately. On the basis of the results above, three inertia forces and the input moment in the mechanism during its idle running were investigated and formulated by dynamic analysis. A verification experiment was performed on a slider-crank mechanism at a high-speed press machine. The forces derived from the established formulas were compared respectively with those obtained by the ADAMS software and the classical method of connecting rod mass substitution. It was experimentally found that the proposed formulas have an improved performance over related earlier techniques. By use of these results, a 1000 kN 1250 rpm four-point high-speed press machine was designed and manufactured. The slide of this press is driven by four sets of slider-crank mechanisms with symmetrical layout and opposite rotation directions to counterbalance the horizontal inertia forces. Four eccentric counterbalance blocks were designed to counterbalance the vertical force after their mass and equivalent eccentric radius were formulated. The high-speed press machine designed by the proposed counterbalance method has worked with satisfactory performance and good dynamic balance for more than four years in practical production.

  17. Design optimization of the distributed modal filtering rod fiber for increasing single mode bandwidth

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Laurila, Marko;

    2012-01-01

    . Large preform tolerances are compensated during the fiber draw resulting in ultra low NA fibers with very large cores. In this paper, design optimization of the SM bandwidth of the DMF rod fiber is presented. Analysis of band gap properties results in a fourfold increase of the SM bandwidth compared......High-power fiber amplifiers for pulsed applications require large mode area (LMA) fibers having high pump absorption and near diffraction limited output. This improves the limiting factor of nonlinear effects, while maintaining good beam quality. Photonic crystal fibers allow realization of short...... to previous results, achieved by utilizing the first band of cladding modes. This covers of a large fraction of the Yb emission band, where wavelengths of 1030 nm and 1064 nm can be included....

  18. Influence of Reduced Graphene Oxide on Effective Absorption Bandwidth Shift of Hybrid Absorbers.

    Directory of Open Access Journals (Sweden)

    Shahid Ameer

    Full Text Available The magnetic nanoparticle composite NiFe2O4 has traditionally been studied for high-frequency microwave absorption with marginal performance towards low-frequency radar bands (particularly L and S bands. Here, NiFe2O4 nanoparticles and nanohybrids using large-diameter graphene oxide (GO sheets are prepared via solvothermal synthesis for low-frequency wide bandwidth shielding (L and S radar bands. The synthesized materials were characterized using XRD, SEM, FTIR and microwave magneto dielectric spectroscopy. The dimension of these solvothermally synthesized pristine particles and hybrids lies within 30-58 nm. Microwave magneto-dielectric spectroscopy was performed in the low-frequency region in the 1 MHz-3 GHz spectrum. The as-synthesized pristine nanoparticles and hybrids were found to be highly absorbing for microwaves throughout the L and S radar bands ( 4 GHz with limited selective bandwidth.

  19. Narrow bandwidth Thomson photon source development using Laser-Plasma Accelerators

    Science.gov (United States)

    Geddes, C. G. R.; van Tilborg, J.; Tsai, H.-E.; Toth, Cs.; Vay, J.-L.; Lehe, R.; Schroeder, C. B.; Esarey, E.; Rykovanov, S. G.; Grote, D. P.; Friedman, A.; Leemans, W. P.

    2016-10-01

    Compact, high-quality photon sources at MeV energies are being developed based on Laser-Plasma Accelerators (LPAs). An independent scattering laser with controlled pulse shaping in frequency and amplitude can be used together with laser guiding to realize high photon yield and narrow bandwidth. Simulations are presented on production of controllable narrow bandwidth sources using the beam and plasma capabilities of LPAs. Recent experiments and simulations demonstrate controllable LPAs in the energy range appropriate to MeV Thomson sources. Design of experiments and laser capabilities to combine these elements will be presented, towards a compact photon source system. A dedicated facility under construction will be described. Work supported by US DOE NNSA DNN R&D and by Sc. HEP under contract DE-AC02-05CH11231.

  20. A comparison of low- and high-impact forced exercise: Effects of training paradigm on learning and memory

    Science.gov (United States)

    Kennard, John A.; Woodruff-Pak, Diana S.

    2012-01-01

    In this study we compared two types of forced exercise—a low impact paradigm to minimize stress, which included speeds up to 10 m/min and a stressful high impact paradigm, with speeds up to 21 m/min. 150 male C57BL/6J mice were randomly assigned to the low impact, high impact, or sedentary control conditions and were tested on the rotorod and Morris water maze (MWM) as indices of motor learning and spatial memory. We found that five weeks of stressful high speed forced exercise led to significant improvement in rotorod performance, as high impact runners outperformed both low impact runners and controls at 15 and 25 RPM speeds. These differences were the result of improved physical fitness due to exercise and likely do not reflect enhanced learning in these mice. In the MWM, five weeks of stressful high impact exercise led to significant impairment in spatial memory acquisition compared to low impact runners and controls. Low impact exercise for 10 weeks significantly improved retention of spatial memory compared to high impact exercise. Results suggested that these two paradigms produced different effects of forced exercise on learning and memory. The low impact paradigm led to some improvements, whereas the stressful high impact program caused significant impairment. Comparison of these two paradigms begins to address the window between the beneficial and detrimental effects of forced exercise, and have suggested a boundary of exercise intensity that leads to impairment in learning. PMID:22402029

  1. A comparison of low- and high-impact forced exercise: effects of training paradigm on learning and memory.

    Science.gov (United States)

    Kennard, John A; Woodruff-Pak, Diana S

    2012-06-25

    In this study we compared two types of forced exercise-a low impact paradigm to minimize stress, which included speeds up to 10 m/min and a stressful high impact paradigm, with speeds up to 21 m/min. 150 male C57BL/6J mice were randomly assigned to the low impact, high impact, or sedentary control conditions and were tested on the rotorod and Morris water maze (MWM) as indices of motor learning and spatial memory. We found that 5 weeks of stressful high speed forced exercise led to significant improvement in rotorod performance, as high impact runners outperformed both low impact runners and controls at 15 and 25 rpm speeds. These differences were the result of improved physical fitness due to exercise and likely do not reflect enhanced learning in these mice. In the MWM, 5 weeks of stressful high impact exercise led to significant impairment in spatial memory acquisition compared to low impact runners and controls. Low impact exercise for 10 weeks significantly improved retention of spatial memory compared to high impact exercise. Results suggested that these two paradigms produced different effects of forced exercise on learning and memory. The low impact paradigm led to some improvements, whereas the stressful high impact program caused significant impairment. Comparison of these two paradigms begins to address the window between the beneficial and detrimental effects of forced exercise, and have suggested a boundary of exercise intensity that leads to impairment in learning.

  2. Programmable bandwidth management in software-defined EPON architecture

    Science.gov (United States)

    Li, Chengjun; Guo, Wei; Wang, Wei; Hu, Weisheng; Xia, Ming

    2016-07-01

    This paper proposes a software-defined EPON architecture which replaces the hardware-implemented DBA module with reprogrammable DBA module. The DBA module allows pluggable bandwidth allocation algorithms among multiple ONUs adaptive to traffic profiles and network states. We also introduce a bandwidth management scheme executed at the controller to manage the customized DBA algorithms for all date queues of ONUs. Our performance investigation verifies the effectiveness of this new EPON architecture, and numerical results show that software-defined EPONs can achieve less traffic delay and provide better support to service differentiation in comparison with traditional EPONs.

  3. Modeling of Bandwidth Aggregation over Heterogeneous Wireless Access Networks

    DEFF Research Database (Denmark)

    Popovska Avramova, Andrijana; Dittmann, Lars

    2012-01-01

    Motivated by the multihomming capability of the mobile devices and the fact that the heterogeneous wireless access networks overlap in coverage, mobile operators are looking for solutions that will benefit by simultaneous use of the available multiple access interfaces. Multipath or multilink...... transfer deals with the problem on how to effectively aggregate the bandwidth by simultaneous usage of heterogeneous networks that a host is attached to in order to improve the throughput. This paper deals with a simulation based analysis of bandwidth aggregation techniques and their impact on higher layer...

  4. A meta-substrate to enhance the bandwidth of metamaterials.

    Science.gov (United States)

    Chen, Hongsheng; Wang, Zuojia; Zhang, Runren; Wang, Huaping; Lin, Shisheng; Yu, Faxin; Moser, Herbert O

    2014-06-12

    We propose the concept of a meta-substrate to broaden the bandwidth of left-handed metamaterials. The meta-substrate, which behaves like an inhomogeneous magnetic substrate, is composed of another kind of magnetic metamaterials like metallic closed rings. When conventional metamaterial rings are printed on this kind of meta-substrate in a proper way, the interaction of the metamaterials units can be greatly enhanced, yielding an increased bandwidth of negative permeability. An equivalent circuit analytical model is used to quantitatively characterize this phenomenon. Both numerical and experimental demonstrations are carried out, showing good agreement with theoretical predictions.

  5. Extending the Bandwidth of Electric Ring Resonator Metamaterial Absorber

    Institute of Scientific and Technical Information of China (English)

    LUO Hao; WANG Tao; GONG Rong-Zhou; NIE Yan; WANG Xian

    2011-01-01

    An efficient method is proposed to extend the bandwidth of a metamaterial absorber with multi-resonance structure. The basic unit cell of a metamaterial absorber consists of the electric ring resonator, dielectric substrate (FR-4)and split-wire. By assembling five sandwiched structures with different geometric dimensions into a unit cell, we obtain the superposition of five different absorption peaks.Finally the bandwidth of metamaterial absorption is extended and the full width at half maximum is up to 1.3 GHz. The simulated and experimental results are consistent.

  6. Theory of polaron bandwidth narrowing in organic molecular crystals

    Science.gov (United States)

    Hannewald, K.; Stojanović, V. M.; Schellekens, J. M.; Bobbert, P. A.; Kresse, G.; Hafner, J.

    2004-02-01

    We present a theoretical description of polaron bandwidth narrowing in organic molecular crystals. Based on a solution of a Holstein-Peierls model for tightly bound electrons interacting with phonons, an explicit expression for the temperature dependence of the electronic bandwidths is found. This formula generalizes the result of Holstein polaron theory by treating local and nonlocal electron-phonon coupling on equal footing. The usefulness of the method is demonstrated by model studies for oligo-acene crystals from which microscopic insight into the relevance of the different coupling mechanisms is obtained.

  7. Extensive wet episodes in Late Glacial Australia resulting from high-latitude forcings

    Science.gov (United States)

    Bayon, Germain; De Deckker, Patrick; Magee, John W.; Germain, Yoan; Bermell, Sylvain; Tachikawa, Kazuyo; Norman, Marc D.

    2017-01-01

    Millennial-scale cooling events termed Heinrich Stadials punctuated Northern Hemisphere climate during the last glacial period. Latitudinal shifts of the intertropical convergence zone (ITCZ) are thought to have rapidly propagated these abrupt climatic signals southward, influencing the evolution of Southern Hemisphere climates and contributing to major reorganisation of the global ocean-atmosphere system. Here, we use neodymium isotopes from a marine sediment core to reconstruct the hydroclimatic evolution of subtropical Australia between 90 to 20 thousand years ago. We find a strong correlation between our sediment provenance proxy data and records for western Pacific tropical precipitations and Australian palaeolakes, which indicates that Northern Hemisphere cooling phases were accompanied by pronounced excursions of the ITCZ and associated rainfall as far south as about 32°S. Comparatively, however, each of these humid periods lasted substantially longer than the mean duration of Heinrich Stadials, overlapping with subsequent warming phases of the southern high-latitudes recorded in Antarctic ice cores. In addition to ITCZ-driven hydroclimate forcing, we infer that changes in Southern Ocean climate also played an important role in regulating late glacial atmospheric patterns of the Southern Hemisphere subtropical regions.

  8. A high-pressure atomic force microscope for imaging in supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Lea, A. S.; Higgins, S. R.; Knauss, K. G.; Rosso, K. M.

    2011-01-01

    A high-pressure atomic force microscope(AFM) that enables in situ, atomic scale measurements of topography of solid surfaces in contact with supercritical CO2 (scCO2) fluids has been developed. This apparatus overcomes the pressure limitations of the hydrothermal AFM and is designed to handle pressures up to 100 atm at temperatures up to ~350 K. A standard optically-based cantilever deflection detection system was chosen. When imaging in compressible supercritical fluids such as scCO2, precise control of pressure and temperature in the fluid cell is the primary technical challenge. Noise levels and imaging resolution depend on minimization of fluid density fluctuations that change the fluidrefractive index and hence the laser path. We demonstrate with our apparatus in situ atomic scale imaging of a calcite (CaCO3) mineral surface in scCO2; both single, monatomic steps and dynamic processes occurring on the (101¯4) surface are presented. Finally, this new AFM provides unprecedented in situ access to interfacial phenomena at solid–fluid interfaces under pressure.

  9. High-speed atomic force microscopy shows that annexin V stabilizes membranes on the second timescale

    Science.gov (United States)

    Miyagi, Atsushi; Chipot, Christophe; Rangl, Martina; Scheuring, Simon

    2016-09-01

    Annexins are abundant cytoplasmic proteins that can bind to negatively charged phospholipids in a Ca2+-dependent manner, and are known to play a role in the storage of Ca2+ and membrane healing. Little is known, however, about the dynamic processes of protein-Ca2+-membrane assembly and disassembly. Here we show that high-speed atomic force microscopy (HS-AFM) can be used to repeatedly induce and disrupt annexin assemblies and study their structure, dynamics and interactions. Our HS-AFM set-up is adapted for such biological applications through the integration of a pumping system for buffer exchange and a pulsed laser system for uncaging caged compounds. We find that biochemically identical annexins (annexin V) display different effective Ca2+ and membrane affinities depending on the assembly location, providing a wide Ca2+ buffering regime while maintaining membrane stabilization. We also show that annexin is membrane-recruited and forms stable supramolecular assemblies within ˜5 s in conditions that are comparable to a membrane lesion in a cell. Molecular dynamics simulations provide atomic detail of the role played by Ca2+ in the reversible binding of annexin to the membrane surface.

  10. Wide-area scanner for high-speed atomic force microscopy.

    Science.gov (United States)

    Watanabe, Hiroki; Uchihashi, Takayuki; Kobashi, Toshihide; Shibata, Mikihiro; Nishiyama, Jun; Yasuda, Ryohei; Ando, Toshio

    2013-05-01

    High-speed atomic force microscopy (HS-AFM) has recently been established. The dynamic processes and structural dynamics of protein molecules in action have been successfully visualized using HS-AFM. However, its maximum scan ranges in the X- and Y-directions have been limited to ~1 μm and ~4 μm, respectively, making it infeasible to observe the dynamics of much larger samples, including live cells. Here, we develop a wide-area scanner with a maximum XY scan range of ~46 × 46 μm(2) by magnifying the displacements of stack piezoelectric actuators using a leverage mechanism. Mechanical vibrations produced by fast displacement of the X-scanner are suppressed by a combination of feed-forward inverse compensation and the use of triangular scan signals with rounded vertices. As a result, the scan speed in the X-direction reaches 6.3 mm/s even for a scan size as large as ~40 μm. The nonlinearity of the X- and Y-piezoelectric actuators' displacements that arises from their hysteresis is eliminated by polynomial-approximation-based open-loop control. The interference between the X- and Y-scanners is also eliminated by the same technique. The usefulness of this wide-area scanner is demonstrated by video imaging of dynamic processes in live bacterial and eukaryotic cells.

  11. Modeling the effect of intercalators on the high-force stretching behavior of DNA

    CERN Document Server

    Schakenraad, Koen; Biebricher, Andreas; Wuite, Gijs; Storm, Cornelis; van der Schoot, Paul

    2015-01-01

    DNA is structurally and mechanically altered by the binding of intercalator molecules. Intercalation strongly affects the force-extension behavior of DNA, in particular the overstretching transition. We present a statistical model that captures all relevant findings of recent force-extension experiments. Two predictions from our model are presented. The first suggests the existence of a novel hyper-stretching regime in the presence of intercalators and the second, a linear dependence of the overstretching force on intercalator concentration, is verified by re-analyzing available experimental data. Our model pins down the physical principles that govern intercalated DNA mechanics, providing a predictive understanding of its limitations and possibilities.

  12. Propagation and Breaking at High Altitudes of Gravity Waves Excited by Tropospheric Forcing

    Science.gov (United States)

    Prusa, Joseph M.; Smolarkiewicz, Piotr K.; Garcia, Rolando R.

    1996-01-01

    An anelastic approximation is used with a time-variable coordinate transformation to formulate a two-dimensional numerical model that describes the evolution of gravity waves. The model is solved using a semi-Lagrangian method with monotone (nonoscillatory) interpolation of all advected fields. The time-variable transformation is used to generate disturbances at the lower boundary that approximate the effect of a traveling line of thunderstorms (a squall line) or of flow over a broad topographic obstacle. The vertical propagation and breaking of the gravity wave field (under conditions typical of summer solstice) is illustrated for each of these cases. It is shown that the wave field at high altitudes is dominated by a single horizontal wavelength; which is not always related simply to the horizontal dimension of the source. The morphology of wave breaking depends on the horizontal wavelength; for sufficiently short waves, breaking involves roughly one half of the wavelength. In common with other studies, it is found that the breaking waves undergo "self-acceleration," such that the zonal-mean intrinsic frequency remains approximately constant in spite of large changes in the background wind. It is also shown that many of the features obtained in the calculations can be understood in terms of linear wave theory. In particular, linear theory provides insights into the wavelength of the waves that break at high altitudes, the onset and evolution of breaking. the horizontal extent of the breaking region and its position relative to the forcing, and the minimum and maximum altitudes where breaking occurs. Wave breaking ceases at the altitude where the background dissipation rate (which in our model is a proxy for molecular diffusion) becomes greater than the rate of dissipation due to wave breaking, This altitude, in effect, the model turbopause, is shown to depend on a relatively small number of parameters that characterize the waves and the background state.

  13. Reducing the Disk IO Bandwidth Bottleneck through Fast Floating Point Compression using Accelerators

    Directory of Open Access Journals (Sweden)

    Ajith Padyana

    2014-03-01

    Full Text Available Compute-intensive tasks in high-end high performance computing (HPC systems often generate large amounts of data, especially floating-point data that need to be transmitted over the network. Although computation speeds are very high, the overall performance of these applications is affected by the data transfer overhead. Moreover, as data sets are growing in size rapidly, bandwidth limitations pose a serious bottleneck in several scientific applications. Fast floating point compression can ameliorate the bandwidth limitations. If data is compressed well, then the amount of data transfer is reduced. This reduction in data transfer time comes at the expense of the increased computation required by compression and decompression. It is important for compression and decompression rates to be greater than the network bandwidth; otherwise, it will be faster to transmit uncompressed data directly [1]. Accelerators such as Graphics Processing Units (GPU provide much computational power. In this paper, we show that the computational power of GPUs and CellBE processor can be harnessed to provide sufficiently fast compression and decompression for this approach to be effective for data produced by many practical applications. In particularly, we use Holt`s Exponential smoothing algorithm from time series analysis, and encode the difference between its predictions and the actual data. This yields a lossless compression scheme. We show that it can be implemented efficiently on GPUs and CellBE to provide an effective compression scheme for the purpose of saving on data transfer overheads The primary contribution of this work lies in demonstrating the potential of floating point compression in reducing the I/O bandwidth bottleneck on modern hardware for important classes of scientific applications.

  14. Control of fingertip forces in young and older adults pressing against fixed low- and high-friction surfaces.

    Directory of Open Access Journals (Sweden)

    Kevin G Keenan

    Full Text Available Mobile computing devices (e.g., smartphones and tablets that have low-friction surfaces require well-directed fingertip forces of sufficient and precise magnitudes for proper use. Although general impairments in manual dexterity are well-documented in older adults, it is unclear how these sensorimotor impairments influence the ability of older adults to dexterously manipulate fixed, low-friction surfaces in particular. 21 young and 18 older (65+ yrs adults produced maximal voluntary contractions (MVCs and steady submaximal forces (2.5 and 10% MVC with the fingertip of the index finger. A Teflon covered custom-molded splint was placed on the fingertip. A three-axis force sensor was covered with either Teflon or sandpaper to create low- and high-friction surfaces, respectively. Maximal downward forces (F(z were similar (p = .135 for young and older adults, and decreased by 15% (p<.001 while pressing on Teflon compared to sandpaper. Fluctuations in F(z during the submaximal force-matching tasks were 2.45× greater (p<.001 for older adults than in young adults, and reached a maximum when older adults pressed against the Teflon surface while receiving visual feedback. These age-associated changes in motor performance are explained, in part, by altered muscle activity from three hand muscles and out-of-plane forces. Quantifying the ability to produce steady fingertip forces against low-friction surfaces may be a better indicator of impairment and disability than the current practice of evaluating maximal forces with pinch meters. These age-associated impairments in dexterity while interacting with low-friction surfaces may limit the use of the current generation of computing interfaces by older adults.

  15. Force measurements on natural membrane nanovesicles reveal a composition-independent, high Young's modulus

    Science.gov (United States)

    Calò, Annalisa; Reguera, David; Oncins, Gerard; Persuy, Marie-Annick; Sanz, Guenhaël; Lobasso, Simona; Corcelli, Angela; Pajot-Augy, Edith; Gomila, Gabriel

    2014-01-01

    Mechanical properties of nano-sized vesicles made up of natural membranes are crucial to the development of stable, biocompatible nanocontainers with enhanced functional, recognition and sensing capabilities. Here we measure and compare the mechanical properties of plasma and inner membrane nanovesicles ~80 nm in diameter obtained from disrupted yeast Saccharomyces cerevisiae cells. We provide evidence of a highly deformable behaviour for these vesicles, able to support repeated wall-to-wall compressions without irreversible deformations, accompanied by a noticeably high Young's modulus (~300 MPa) compared to that obtained for reconstituted artificial liposomes of similar size and approaching that of some virus particles. Surprisingly enough, the results are approximately similar for plasma and inner membrane nanovesicles, in spite of their different lipid compositions, especially on what concerns the ergosterol content. These results point towards an important structural role of membrane proteins in the mechanical response of natural membrane vesicles and open the perspective to their potential use as robust nanocontainers for bioapplications.Mechanical properties of nano-sized vesicles made up of natural membranes are crucial to the development of stable, biocompatible nanocontainers with enhanced functional, recognition and sensing capabilities. Here we measure and compare the mechanical properties of plasma and inner membrane nanovesicles ~80 nm in diameter obtained from disrupted yeast Saccharomyces cerevisiae cells. We provide evidence of a highly deformable behaviour for these vesicles, able to support repeated wall-to-wall compressions without irreversible deformations, accompanied by a noticeably high Young's modulus (~300 MPa) compared to that obtained for reconstituted artificial liposomes of similar size and approaching that of some virus particles. Surprisingly enough, the results are approximately similar for plasma and inner membrane nanovesicles, in

  16. Levitation force from high-Tc superconducting thin-film disks

    Science.gov (United States)

    Riise, Anjali B.; Johansen, T. H.; Bratsberg, H.; Koblischka, M. R.; Shen, Y. Q.

    1999-10-01

    Experimental studies and theoretical modeling of the levitation force between a permanent magnet and superconducting thin film are reported. Measurements of the force Fz and magnetic stiffness κz=\\|δFz/δz\\| as functions of the magnet-superconductor separation z, show several features contrasting all previous levitation force data for bulk superconductors. In particular, the Fz(z) curves measured for decreasing and increasing separation form hysteresis loops of nearly symmetrical shape, also displaying a peak in the repulsive force branch. Recent theories for flux penetration in thin type-II superconductors in transverse magnetic fields are invoked to explain the results, which were obtained using a cylindrical Nd-Fe-B magnet and a YBa2Cu3O7-δ circular disk made by laser ablation. We derive explicit formulas for both Fz and κz, reproducing quantitatively all the features seen experimentally.

  17. Integrated dynamic and static tactile sensor: focus on static force sensing

    Science.gov (United States)

    Wettels, Nicholas; Pletner, Baruch

    2012-04-01

    Object grasping by robotic hands in unstructured environments demands a sensor that is durable, compliant, and responsive to static and dynamic force conditions. In order for a tactile sensor to be useful for grasp control in these, it should have the following properties: tri-axial force sensing (two shear plus normal component), dynamic event sensing across slip frequencies, compliant surface for grip, wide dynamic range (depending on application), insensitivity to environmental conditions, ability to withstand abuse and good sensing behavior (e.g. low hysteresis, high repeatability). These features can be combined in a novel multimodal tactile sensor. This sensor combines commercial-off-the-shelf MEMS technology with two proprietary force sensors: a high bandwidth device based on PZT technology and low bandwidth device based on elastomers and optics. In this study, we focus on the latter transduction mechanism and the proposed architecture of the completed device. In this study, an embedded LED was utilized to produce a constant light source throughout a layer of silicon rubber which covered a plastic mandrel containing a set of sensitive phototransistors. Features about the contacted object such as center of pressure and force vectors can be extracted from the information in the changing patterns of light. The voltage versus force relationship obtained with this molded humanlike finger had a wide dynamic range that coincided with forces relevant for most human grip tasks.

  18. Improving Sensitivity and Bandwidth of an Atomic Magnetometer using Quantum Non-Demolition Measurement

    Science.gov (United States)

    Shah, Vishal; Vasilakis, Georgios; Romalis, Michael

    2009-05-01

    The fundamental sensitivity of an atomic magnetometer is limited by spin projection noise. In the case of uniform spin relaxation, it is well understood that it is not possible to improve the sensitivity using spin squeezing induced by quantum non-demolition (QND) measurement for measurement time scales longer than spin relaxation time [1, 2]. It is however possible to increase the bandwidth of the magnetometer using QND measurement. Here we experimentally demonstrate, in excellent agreement with the theory, an improvement in the bandwidth of our scalar alkali vapor atomic magnetometer using continuous QND measurement. We also investigate the possibility of improving sensitivity of our magnetometer in the special case in which the spin relaxation is time dependent. The case of time dependent spin relaxation naturally arises in high polarization regime in an alkali-alkali spin-exchange relaxation dominated atomic sample. [1] S. F. Huelga, Phys. Rev. Lett. 79, 3865 -- 3868, 1997. [2] M. Auzinsh, Phys. Rev. Lett. 93, 173002, 2004.

  19. Optimization of Connector Position Offset for Bandwidth Enhancement of a Multimode Optical Fiber Link

    Science.gov (United States)

    Rawat, Banmali

    2000-01-01

    The multimode fiber bandwidth enhancement techniques to meet the Gigabit Ethernet standards for local area networks (LAN) of the Kennedy Space Center and other NASA centers have been discussed. Connector with lateral offset coupling between single mode launch fiber cable and the multimode fiber cable has been thoroughly investigated. An optimization of connector position offset for 8 km long optical fiber link at 1300 nm with 9 micrometer diameter single mode fiber (SMF) and 50 micrometer diameter multimode fiber (MMF) coupling has been obtained. The optimization is done in terms of bandwidth, eye-pattern, and bit pattern measurements. It is simpler, is a highly practical approach and is cheaper as no additional cost to manufacture the offset type of connectors is involved.

  20. Narrow-bandwidth solar upconversion: design principles, efficiency limits, and case studies

    CERN Document Server

    Briggs, Justin A; Dionne, Jennifer A

    2013-01-01

    We employ a detailed balance approach to model a single-junction solar cell with a realistic narrow-band, non-unity-quantum-yield upconverter. As upconverter bandwidths are increased from 0 to 0.5 eV, maximum cell efficiencies increase from the Shockley-Queisser limit of 30.58% to over 43%. Such efficiency enhancements are calculated for upconverters with near-infrared spectral absorption bands, readily accessible with existing upconverters. While our model shows that current bimolecular and lanthanide-based upconverting materials will improve cell efficiencies by <1%, cell efficiencies can increase by several absolute percent with increased upconverter quantum yield - even without an increased absorption bandwidth. By examining the efficiency limits of a highly realistic solar cell-upconverter system, our model provides a platform for optimizing future solar upconverter designs.