WorldWideScience

Sample records for small-signal 3db bandwidth

  1. Small Signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2014-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterized by the mechanical resonance between the mass of the diaphragm and the compliance of its suspension which vary from driver to driver. Therefore, a loudspeaker emulator capable of adjusting its impedance to that of a given driver is desired for measurement purposes. This paper proposes a loudspeaker emulator circuit for small signals. Simulations and experimental results are compared and show that it is possible to emulate the loudspeaker impedance with an electric circuit and that its resonance frequency can be changed by tuning two resistors.

  2. Small-signal analysis of a rectangular helix structure traveling-wave-tube

    International Nuclear Information System (INIS)

    This paper investigates the properties of traveling wave-beam interaction in a rectangular helix traveling-wave-tube (TWT) for a solid sheet electron beam. The 'hot' dispersion equation is obtained by means of the self-consistent field theory. The small signal analysis, which includes the effects of the beam parameters and slow-wave structure (SWS) parameters, is carried out by theoretical computation. The numerical results show that the bandwidth and the small-signal gain of the rectangular helix TWT increase as the beam current increases; and the beam voltage not obviously influences the small signal gain. Among different rectangular helix structures, the small-signal gain increases as the width of the rectangular helix SWS increases, however, the bandwidth decreases whether structure parameters a and L or ? and L are fixed or not. In addition, a comparison of the small-signal gain of this structure with a conventional round helix is made. The presented analysis will be useful for the design of the TWT with a rectangular helix circuit. (classical areas of phenomenology)

  3. Small-signal modulation characteristics of a polariton laser

    Science.gov (United States)

    Zunaid Baten, Md; Frost, Thomas; Iorsh, Ivan; Deshpande, Saniya; Kavokin, Alexey; Bhattacharya, Pallab

    2015-01-01

    Use of large bandgap materials together with electrical injection makes the polariton laser an attractive low-power coherent light source for medical and biomedical applications or short distance plastic fiber communication at short wavelengths (violet and ultra-violet), where a conventional laser is difficult to realize. The dynamic properties of a polariton laser have not been investigated experimentally. We have measured, for the first time, the small signal modulation characteristics of a GaN-based electrically pumped polariton laser operating at room temperature. A maximum ?3?dB modulation bandwidth of 1.18?GHz is measured. The experimental results have been analyzed with a theoretical model based on the Boltzmann kinetic equations and the agreement is very good. We have also investigated frequency chirping during such modulation. Gain compression phenomenon in a polariton laser is interpreted and a value is obtained for the gain compression factor. PMID:26154681

  4. Small-signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Knott, Arnold; Iversen, Niels Elkjær

    2014-01-01

    Specifying the performance of audio ampliers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by the mechanical resonance between the mass of the diaphragm and the compliance of its' suspension which vary from driver to driver. Therefore a loudspeaker emulator capable of adjusting its' impedance to a given driver is in need for measurement purposes. This paper proposes a loudspeaker emulator circuit for small signals. Simulations and experimental results are compared and show that it is possible to emulate the loudspeaker impedance with an electric circuit and that its' resonance frequency can be changed by tuning two resistors.

  5. A New Circuit Model of Small-Signal Sziklai Pair Amplifier

    Directory of Open Access Journals (Sweden)

    SachchidaNand Shukla and Susmrita Srivastava

    2013-07-01

    Full Text Available A new circuit model of RC coupled small-signal Sziklai pair amplifier is proposed and qualitatively analyzed for the first time. The circuit of proposed amplifier uses a Sziklai pair with NPN driver and crops high voltage gain (237.916, moderate bandwidth (15.10KHz, fairly high current gain (712.075 and considerably low THD (0.73% at 1mV, 1KHz input AC signal. This circuit can be tuned in specific audible frequency range, extending approximately from 1Hz to 20KHz. Tuning performance makes this amplifier circuit suitable to use in Radio and TV receiver stages. The qualitative and tuning performance of the proposed amplifier offers it a flexible application range as high voltage gain, high power gain and tuned amplifier. Tuning performance, variation of voltage gain with frequency and different biasing resistances, input and output noises at operating frequency, temperature dependency of performance parameters and total harmonic distortion of the amplifier are perused for providing wide spectrum to the qualitative studies. The proposed Sziklai pair configuration with NPN driver transistor can be attempted to fabricate a single pack transistor IC version of Sziklai pair. Proposed circuit is also free from poor response problem of small-signal Darlington pair amplifiers at higher frequencies and narrow-band response region for PNP driven small-signal Sziklai pair amplifier.

  6. Small-signal Amplifier with Three Dissimilar Active Devices in Triple Darlington Topology

    Directory of Open Access Journals (Sweden)

    DR.SACHCHIDANAND SHUKLA

    2013-06-01

    Full Text Available A new circuit model of a small-signal amplifier is proposed and analyzed on the qualitative scale. Apart from routine biasing components, the proposed amplifier circuit uses two additional biasing resistances and three dissimilar active devices namely MOSFET, JFET and BJT in Triple Darlington configuration. Having a considerably low amount of distortion (0.71%, the proposed circuit successfully amplifies small-signals of 1-5mV range (at 1 KHz frequency and simultaneously provides high voltage gain (189.846 and high current gain (16.542K with moderate range bandwidth (369.529KHz. These properties offer a flexible application range to the proposed circuit as high voltage gain or high current gain or high power gain amplifier in permissible audio-frequency range. Variations in voltage gain as a function of frequency and different biasing resistances, temperature dependency of performance parameters, bandwidth and total harmonic distortion of the amplifier are perused to provide a wide spectrum to the qualitative studies. Qualitative performance of the proposed amplifier is also compared with two different circuits which are respectively having BJT-JFET and BJT-MOSFET in Darlington pair configuration. The proposed amplifier may be useful for those applications where high voltage and current gain would be the prime requirement of amplification in audio frequency region.

  7. Thermal Effects and Small Signal Modulation of 1.3-?m InAs/GaAs Self-Assembled Quantum-Dot Lasers

    OpenAIRE

    Zhao, Hx; Yoon, Sf; Tong, Cz; Liu, Cy; Wang, R.; Cao, Q.

    2010-01-01

    We investigate the influence of thermal effects on the high-speed performance of 1.3-?m InAs/GaAs quantum-dot lasers in a wide temperature range (5–50°C). Ridge waveguide devices with 1.1 mm cavity length exhibit small signal modulation bandwidths of 7.51 GHz at 5°C and 3.98 GHz at 50°C. Temperature-dependent K-factor, differential gain, and gain compression factor are studied. While the intrinsic damping-limited modulation bandwidth is as high as 23 GHz, the actual modulation bandwidth...

  8. Power system small signal stability analysis and control

    CERN Document Server

    Mondal, Debasish; Sengupta, Aparajita

    2014-01-01

    Power System Small Signal Stability Analysis and Control presents a detailed analysis of the problem of severe outages due to the sustained growth of small signal oscillations in modern interconnected power systems. The ever-expanding nature of power systems and the rapid upgrade to smart grid technologies call for the implementation of robust and optimal controls. Power systems that are forced to operate close to their stability limit have resulted in the use of control devices by utility companies to improve the performance of the transmission system against commonly occurring power system

  9. Small-Signal Amplifier with MOSFET and BJT in Triple Darlington Configuration

    Directory of Open Access Journals (Sweden)

    SUSMRITA SRIVASTAVA

    2013-02-01

    Full Text Available A new circuit model of a small-signal narrow-band amplifier is proposed and analyzed on the qualitative scale. Proposed amplifier uses two MOSFETs and a BJT in Triple Darlington configuration with two additional biasing resistances in the circuit. With low distortion percentage (1.28%, the proposed circuit successfully amplifies small-signals of 1-10mV range and simultaneously provides high voltage gain (311.593 and current gain (13.971K with narrow bandwidth (9.665KHz. Variations of maximum voltage gain with different biasing resistances and DC supply voltage and the temperature sensitivity of various performance parameters are elaborately studied and discussed in length. Qualitative performance of the proposed amplifier is also compared with the circuit which is having BJT-MOSFET in Darlington pair configuration. The proposed amplifier can be used to process audio range signal excursions and may be useful for those applications where high voltage and current gain would be the prime requirement of amplification in narrow-band low frequency region.

  10. A Novel Circuit Model of Small-Signal Amplifier Developed by Using BJT-JFET-BJT in Triple Darlington Configuration

    Directory of Open Access Journals (Sweden)

    SACHCHIDANAND SHUKLA

    2013-05-01

    Full Text Available Two distinct configurations of small-signal amplifiers, consisting hybrid combination of BJT-FET-BJT in Triple Darlington topology, are proposed and qualitatively analyzed perhaps for the first time. The first proposed amplifier crops high voltage with moderate current gain and bandwidth in 1-15mV input signal range at 1 KHz frequency. However, the second amplifier is configured by creating certain modifications in the first circuit. This amplifier produces about double voltage and current gain than the first amplifier circuit with almost half bandwidth in 1-4mV input-signal-range at 1 KHz frequency. Both the amplifier circuits include two additional biasing resistances. Variations in voltage gain as a function of frequency and different biasing resistances, temperature dependency of performance parameters, bandwidth and total harmonic distortion of the amplifiers are also perused. The proposed amplifiers can be successfully implemented as high power gain small-signal amplifiers in audio-frequency-range because of the obtained values of the current and voltage gains which are higher than unity.

  11. Small signal modulation characteristics of red-emitting (? = 610 nm) III-nitride nanowire array lasers on (001) silicon

    Science.gov (United States)

    Jahangir, Shafat; Frost, Thomas; Hazari, Arnab; Yan, Lifan; Stark, Ethan; LaMountain, Trevor; Millunchick, Joanna M.; Ooi, Boon S.; Bhattacharya, Pallab

    2015-02-01

    The small signal modulation characteristics of an InGaN/GaN nanowire array edge- emitting laser on (001) silicon are reported. The emission wavelength is 610 nm. Lattice matched InAlN cladding layers were incorporated in the laser heterostructure for better mode confinement. The suitability of the nanowire lasers for use in plastic fiber communication systems with direct modulation is demonstrated through their modulation bandwidth of f-3dB,max = 3.1 GHz, very low values of chirp (0.8 Å) and ?-parameter, and large differential gain (3.1 × 10-17 cm2).

  12. Small signal modulation characteristics of red-emitting (? = 610?nm) III-nitride nanowire array lasers on (001) silicon

    KAUST Repository

    Jahangir, Shafat

    2015-02-16

    The small signal modulation characteristics of an InGaN/GaN nanowire array edge- emitting laser on (001) silicon are reported. The emission wavelength is 610 nm. Lattice matched InAlN cladding layers were incorporated in the laser heterostructure for better mode confinement. The suitability of the nanowire lasers for use in plastic fiber communication systems with direct modulation is demonstrated through their modulation bandwidth of f-3dB,max = 3.1 GHz, very low values of chirp (0.8 Å) and ?-parameter, and large differential gain (3.1 × 10-17 cm2).

  13. Improving Small Signal Stability through Operating Point Adjustment

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhenyu; Zhou, Ning; Tuffner, Francis K.; Chen, Yousu; Trudnowski, Daniel J.; Mittelstadt, William; Hauer, John F.; Dagle, Jeffery E.

    2010-09-30

    ModeMeter techniques for real-time small signal stability monitoring continue to mature, and more and more phasor measurements are available in power systems. It has come to the stage to bring modal information into real-time power system operation. This paper proposes to establish a procedure for Modal Analysis for Grid Operations (MANGO). Complementary to PSS’s and other traditional modulation-based control, MANGO aims to provide suggestions such as increasing generation or decreasing load for operators to mitigate low-frequency oscillations. Different from modulation-based control, the MANGO procedure proactively maintains adequate damping for all time, instead of reacting to disturbances when they occur. Effect of operating points on small signal stability is presented in this paper. Implementation with existing operating procedures is discussed. Several approaches for modal sensitivity estimation are investigated to associate modal damping and operating parameters. The effectiveness of the MANGO procedure is confirmed through simulation studies of several test systems.

  14. DFIG turbine representation for small signal voltage control studies

    OpenAIRE

    Garcia, Jorge Martinez; Kjær, Philip Carne; Teodorescu, Remus

    2010-01-01

    This paper addresses the representation of a wind power plant, based on wound rotor asynchronous generators, with a centralized voltage controller, by an equivalent transfer function, valid for small signal voltage control studies. This representation allows to investigate the influence of the centralized plant control gain and short circuit ratio on the system stability, for instance, by analyzing the zero-pole placement. Larger percentages of wind power penetration translate to more demandi...

  15. Small-signal model for the series resonant converter

    Science.gov (United States)

    King, R. J.; Stuart, T. A.

    1985-01-01

    The results of a previous discrete-time model of the series resonant dc-dc converter are reviewed and from these a small signal dynamic model is derived. This model is valid for low frequencies and is based on the modulation of the diode conduction angle for control. The basic converter is modeled separately from its output filter to facilitate the use of these results for design purposes. Experimental results are presented.

  16. Small-signal modulation and differential gain of red-emitting (??=?630?nm) InGaN/GaN quantum dot lasers

    International Nuclear Information System (INIS)

    We report small-signal modulation bandwidth and differential gain measurements of a ridge waveguide In0.4Ga0.6N/GaN quantum dot laser grown by molecular beam epitaxy. The laser peak emission is at ??=?630?nm. The ?3?dB bandwidth of an 800??m long device was measured to be 2.4?GHz at 250?mA under pulsed biasing, demonstrating the possibility of high-speed operation of these devices. The differential gain was measured to be 5.3?×?10?17?cm2, and a gain compression factor of 2.87?×?10?17?cm3 is also derived from the small-signal modulation response

  17. Gain and bandwidth in stagger-tuned gyroklystrons

    International Nuclear Information System (INIS)

    An analytical theory describing the trade-off in the bandwidth and gain in multicavity, stagger-tuned gyroklystrons (GKLs) is developed. The assumption that the cavities are short and therefore the electron ballistic bunching proceeds in long drift sections (point-gap model) allows us to develop analytically both the small-signal and large-signal theories of stagger-tuned GKLs. The results for two-, three-, and four-cavity GKLs are presented which illustrate the bandwidth increase, the gain degradation, and the increase in gain-bandwidth product due to the stagger tuning. copyright 1997 American Institute of Physics

  18. DFIG turbine representation for small signal voltage control studies

    DEFF Research Database (Denmark)

    Garcia, Jorge Martinez; Kjær, Philip Carne

    2010-01-01

    This paper addresses the representation of a wind power plant, based on wound rotor asynchronous generators, with a centralized voltage controller, by an equivalent transfer function, valid for small signal voltage control studies. This representation allows to investigate the influence of the centralized plant control gain and short circuit ratio on the system stability, for instance, by analyzing the zero-pole placement. Larger percentages of wind power penetration translate to more demanding requirements coming from the grid codes, for example voltage support at the point of connection has been introduced recently by several grid codes from around the world, making important to analyze this control when applied to wind power plants. The performance of the equivalent transfer function has been evaluated and compared using an equivalent grid with different short circuit ratios and active power injection levels, the cases have been simulated with PSCAD/EMTDC program. Results show that this equivalence can be used for short circuit ratios between 5 and 25 for obtaining an accurate representation of the system voltage dynamics.

  19. Analytical theory of a small signal modulation response of a transistor laser with dots-in-well in the base

    International Nuclear Information System (INIS)

    We have developed the theory for the threshold base current, light power output and small signal modulation response of a transistor laser, the base of which contains a quantum well (QW) with a layer of quantum dots (QDs) inserted within it. Our theory involves the solution of the continuity equation for an arbitrary location of the QW in the base, and the solution of coupled rate equations for carriers and photons in the QD. The excitonic recombination model is assumed to be valid in the QD. The estimated threshold base current for InAs QDs embedded in the InGaAs QW is found to be smaller than the value for the InGaAs QW in the GaAs base. The values of the modulation bandwidths for different values of the base current however do not reach the high values obtained for the QW system. (paper)

  20. Variable Bandwidth Diffusion Kernels

    OpenAIRE

    Berry, Tyrus; Harlim, John

    2014-01-01

    Practical applications of kernel methods often use variable bandwidth kernels, also known as self-tuning kernels, however much of the current theory of kernel based techniques is only applicable to fixed bandwidth kernels. In this paper, we derive the asymptotic expansion of these variable bandwidth kernels for arbitrary bandwidth functions; generalizing the theory of Diffusion Maps and Laplacian Eigenmaps. We also derive pointwise error estimates for the corresponding discr...

  1. Intrinsic stability of an HBT based on a small signal equivalent circuit model

    International Nuclear Information System (INIS)

    Intrinsic stability of the heterojunction bipolar transistor (HBT) was analyzed and discussed based on a small signal equivalent circuit model. The stability factor of the HBT device was derived based on a compact T-type small signal equivalent circuit model of the HBT. The effect of the mainly small signal model parameters of the HBT on the stability of the HBT was thoroughly examined. The discipline of parameter optimum to improve the intrinsic stability of the HBT was achieved. The theoretic analysis results of the stability were also used to explain the experimental results of the stability of the HBT and they were verified by the experimental results. (semiconductor devices)

  2. Small-Signal Stability of Wind Power System With Full-Load Converter Interfaced Wind Turbines

    OpenAIRE

    Knu?ppel, Thyge; Nielsen, Jørgen Nygaard; Jensen, Kim Høj; Dixon, Andrew; Østergaard, Jacob

    2012-01-01

    Small-signal stability analysis of power system oscillations is a well established field within power system analysis, but not much attention has yet been paid to systems with a high penetration of wind turbines and with large wind power plants (WPP). In this paper a comprehensive analysis is presented which assesses the impact of full-load converter interfaced wind turbines on power system small-signal stability. The study is based on a 7 generator network with lightly damp...

  3. Study on Small Signal Stability Improvement by PSS of the Large-Scale Wind Power Integration

    Directory of Open Access Journals (Sweden)

    Zi Lan Zhao

    2013-04-01

    Full Text Available With the increasing penetration of wind energy generation into power system, the impact of wind farms on power grids performance and stability control is of growing concern. Firstly there is a introduction of basic principles related to small signal stability analysis. Then a new method of improving small signal stability is proposed in this paper. The method, based on optimization adjustment of time constant of the phase shift link of PSS, is verified to be effective by an instance analysis of simulation in DIgSILENT/Power Factory. Three-machine Nine Nodes Model is used in this simulation.

  4. T3DB: an integrated database for bacterial type III secretion system

    Directory of Open Access Journals (Sweden)

    Wang Yejun

    2012-04-01

    Full Text Available Abstract Background Type III Secretion System (T3SS, which plays important roles in pathogenesis or symbiosis, is widely expressed in a variety of gram negative bacteria. However, lack of unique nomenclature for T3SS genes has hindered T3SS related research. It is necessary to set up a knowledgebase integrating T3SS-related research data to facilitate the communication between different research groups interested in different bacteria. Description A T3SS-related Database (T3DB was developed. T3DB serves as an integrated platform for sequence collection, function annotation, and ortholog classification for T3SS related apparatus, effector, chaperone and regulatory genes. The collection of T3SS-containing bacteria, T3SS-related genes, function annotation, and the ortholog information were all manually curated from literature. BPBAac, a highly efficient T3SS effector prediction tool, was also implemented. Conclusions T3DB is the first systematic platform integrating well-annotated T3SS-related gene and protein information to facilitate T3SS and bacterial pathogenecity related research. The newly constructed T3 ortholog clusters may faciliate effective communication between different research groups and will promote de novo discoveries. Besides, the manually-curated high-quality effector and chaperone data are useful for feature analysis and evolutionary studies of these important proteins.

  5. Resolving small signal measurements in experimental plasma environments using calibrated subtraction of noise signals

    International Nuclear Information System (INIS)

    The performance of many diagnostic and control systems within fusion and other fields of research are often detrimentally affected by spurious noise signals. This is particularly true for those (such as radiation or particle detectors) working with very small signals. Common sources of radiated and conducted noise in experimental fusion environments include the plasma itself and instrumentation. The noise complicates data analysis, as illustrated by noise on signals measured with the heavy ion beam probe (HIBP) installed on the Madison Symmetric Torus. The noise is time-varying and often exceeds the secondary ion beam current (in contrast with previous applications). Analysis of the noise identifies the dominant source as photoelectric emission from the detectors induced by ultraviolet light from the plasma. This has led to the development of a calibrated subtraction technique, which largely removes the undesired temporal noise signals from data. The advantages of the technique for small signal measurement applications are demonstrated through improvements realized on HIBP fluctuation measurements

  6. Resolving small signal measurements in experimental plasma environments using calibrated subtraction of noise signalsa)

    Science.gov (United States)

    Fimognari, P. J.; Demers, D. R.; Chen, X.; Schoch, P. M.

    2014-11-01

    The performance of many diagnostic and control systems within fusion and other fields of research are often detrimentally affected by spurious noise signals. This is particularly true for those (such as radiation or particle detectors) working with very small signals. Common sources of radiated and conducted noise in experimental fusion environments include the plasma itself and instrumentation. The noise complicates data analysis, as illustrated by noise on signals measured with the heavy ion beam probe (HIBP) installed on the Madison Symmetric Torus. The noise is time-varying and often exceeds the secondary ion beam current (in contrast with previous applications). Analysis of the noise identifies the dominant source as photoelectric emission from the detectors induced by ultraviolet light from the plasma. This has led to the development of a calibrated subtraction technique, which largely removes the undesired temporal noise signals from data. The advantages of the technique for small signal measurement applications are demonstrated through improvements realized on HIBP fluctuation measurements.

  7. Small-Signal Stability of Wind Power System With Full-Load Converter Interfaced Wind Turbines

    DEFF Research Database (Denmark)

    Knüppel, Thyge; Nielsen, JØrgen Nygaard

    2012-01-01

    Small-signal stability analysis of power system oscillations is a well established field within power system analysis, but not much attention has yet been paid to systems with a high penetration of wind turbines and with large wind power plants (WPP). In this paper a comprehensive analysis is presented which assesses the impact of full-load converter interfaced wind turbines on power system small-signal stability. The study is based on a 7 generator network with lightly damped inter-area modes. A detailed wind turbine (WT) model with all grid relevant control functions is used in the study. The WT is, furthermore, equipped with a park level WPP voltage controller and comparisons are presented. The WT model for this work is a validated dynamic model of the 3.6 MW Siemens Wind Power WT. The study is based on modal analysis which is complemented with time domain simulations on the nonlinear system.

  8. Resolving small signal measurements in experimental plasma environments using calibrated subtraction of noise signals

    Energy Technology Data Exchange (ETDEWEB)

    Fimognari, P. J., E-mail: PJFimognari@XanthoTechnologies.com; Demers, D. R. [Xantho Technologies, LLC, Madison, Wisconsin 53705 (United States); Chen, X. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37830 (United States); Schoch, P. M. [Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2014-11-15

    The performance of many diagnostic and control systems within fusion and other fields of research are often detrimentally affected by spurious noise signals. This is particularly true for those (such as radiation or particle detectors) working with very small signals. Common sources of radiated and conducted noise in experimental fusion environments include the plasma itself and instrumentation. The noise complicates data analysis, as illustrated by noise on signals measured with the heavy ion beam probe (HIBP) installed on the Madison Symmetric Torus. The noise is time-varying and often exceeds the secondary ion beam current (in contrast with previous applications). Analysis of the noise identifies the dominant source as photoelectric emission from the detectors induced by ultraviolet light from the plasma. This has led to the development of a calibrated subtraction technique, which largely removes the undesired temporal noise signals from data. The advantages of the technique for small signal measurement applications are demonstrated through improvements realized on HIBP fluctuation measurements.

  9. Linewidth considerations in small signal gain or loss measurements with pulses

    International Nuclear Information System (INIS)

    This report discusses the difference between c.w. and pulse small signal gain or loss measurements. The spectrum of the gain or loss medium must be compared to the spectrum of the probe signal. First we discuss the formulation of the problem and apply the results to a Gaussian pulse propagating through a single line Lorentzian gain or loss medium. Second, we calculate the pulse energy gain or loss for the six overlapping lines of the iodine spectrum. (orig.)

  10. The Bandwidth Exchange Architecture

    CERN Document Server

    Turner, D M; Keromytis, A D; Turner, David Michael; Prevelakis, Vassilis; Keromytis, Angelos D.

    2005-01-01

    New applications for the Internet such as video on demand, grid computing etc. depend on the availability of high bandwidth connections with acceptable Quality of Service (QoS). There appears to be, therefore, a requirement for a market where bandwidth-related transactions can take place. For this market to be effective, it must be efficient for both the provider (seller) and the user (buyer) of the bandwidth. This implies that: (a) the buyer must have a wide choice of providers that operate in a competitive environment, (b) the seller must be assured that a QoS transaction will be paid by the customer, and (c) the QoS transaction establishment must have low overheads so that it may be used by individual customers without a significant burden to the provider. In order to satisfy these requirements, we propose a framework that allows customers to purchase bandwidth using an open market where providers advertise links and capacities and customers bid for these services. The model is close to that of a commoditi...

  11. 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.

  12. PolySac3DB: an annotated data base of 3 dimensional structures of polysaccharides

    Directory of Open Access Journals (Sweden)

    Sarkar Anita

    2012-11-01

    Full Text Available Abstract Background Polysaccharides are ubiquitously present in the living world. Their structural versatility makes them important and interesting components in numerous biological and technological processes ranging from structural stabilization to a variety of immunologically important molecular recognition events. The knowledge of polysaccharide three-dimensional (3D structure is important in studying carbohydrate-mediated host-pathogen interactions, interactions with other bio-macromolecules, drug design and vaccine development as well as material science applications or production of bio-ethanol. Description PolySac3DB is an annotated database that contains the 3D structural information of 157 polysaccharide entries that have been collected from an extensive screening of scientific literature. They have been systematically organized using standard names in the field of carbohydrate research into 18 categories representing polysaccharide families. Structure-related information includes the saccharides making up the repeat unit(s and their glycosidic linkages, the expanded 3D representation of the repeat unit, unit cell dimensions and space group, helix type, diffraction diagram(s (when applicable, experimental and/or simulation methods used for structure description, link to the abstract of the publication, reference and the atomic coordinate files for visualization and download. The database is accompanied by a user-friendly graphical user interface (GUI. It features interactive displays of polysaccharide structures and customized search options for beginners and experts, respectively. The site also serves as an information portal for polysaccharide structure determination techniques. The web-interface also references external links where other carbohydrate-related resources are available. Conclusion PolySac3DB is established to maintain information on the detailed 3D structures of polysaccharides. All the data and features are available via the web-interface utilizing the search engine and can be accessed at http://polysac3db.cermav.cnrs.fr.

  13. S3DB core: a framework for RDF generation and management in bioinformatics infrastructures

    Directory of Open Access Journals (Sweden)

    Deus Helena F

    2010-07-01

    Full Text Available Abstract Background Biomedical research is set to greatly benefit from the use of semantic web technologies in the design of computational infrastructure. However, beyond well defined research initiatives, substantial issues of data heterogeneity, source distribution, and privacy currently stand in the way towards the personalization of Medicine. Results A computational framework for bioinformatic infrastructure was designed to deal with the heterogeneous data sources and the sensitive mixture of public and private data that characterizes the biomedical domain. This framework consists of a logical model build with semantic web tools, coupled with a Markov process that propagates user operator states. An accompanying open source prototype was developed to meet a series of applications that range from collaborative multi-institution data acquisition efforts to data analysis applications that need to quickly traverse complex data structures. This report describes the two abstractions underlying the S3DB-based infrastructure, logical and numerical, and discusses its generality beyond the immediate confines of existing implementations. Conclusions The emergence of the "web as a computer" requires a formal model for the different functionalities involved in reading and writing to it. The S3DB core model proposed was found to address the design criteria of biomedical computational infrastructure, such as those supporting large scale multi-investigator research, clinical trials, and molecular epidemiology.

  14. Forecasting international bandwidth capability

    OpenAIRE

    Madden, Gary G.; Coble-neal, Grant

    2005-01-01

    M-competition studies provide a set of stylized recommendations to enhance forecast reliability. However, no single method dominates across series, leading to consideration of the relationship between selected data characteristics and the reliability of alternative forecast methods. This study conducts an analysis of predictive accuracy in relation to Internet bandwidth loads. Extrapolation techniques that perform best in M-competitions perform relatively poorly in predicting Internet b...

  15. Small-signal amplifier based on single-layer MoS2

    OpenAIRE

    Radisavljevic, Branimir; Whitwick, Michael B.; Kis, Andras

    2012-01-01

    In this letter we demonstrate the operation of an analog small-signal amplifier based on single-layer MoS2, a semiconducting analogue of graphene. Our device consists of two transistors integrated on the same piece of single-layer MoS2. The high intrinsic band gap of 1.8 eV allows MoS2-based amplifiers to operate with a room temperature gain of 4. The amplifier operation is demonstrated for the frequencies of input signal up to 2 kHz preserving the gain higher than 1. Our work shows that MoS2...

  16. A transfer function approach to the small-signal response of saturated semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Nielsen, Mads LØnstrup; Blumenthal, D. J.

    2000-01-01

    A theoretical analysis of the small-signal frequency response (SSFR) of a wavelength converter based on cross-gain modulation in a semiconductor optical amplifier with a finite waveguide loss is presented. We use a transfer function formalism to explain the resonant behavior of the frequency response. The limitations to the magnitude of the spectral overshoot are also accounted for. Operating with the data and CW signals in a co-propagating configuration, we End that the resonance only exists for a finite waveguide loss. In a counter-propagating scheme, a resonance can exist regardless of the presence of loss.

  17. Linearized Modeling of Single Machine Infinite Bus Power System and Controllers for Small Signal Stability Investigation and Enhancement

    Directory of Open Access Journals (Sweden)

    Balwinder Singh Surjan

    2012-10-01

    Full Text Available Small signal stability investigation is vital as thesystem outage due small signal perturbation being unknown tothe system operators. The small signal disturbance may beinitiating event for large system outage. The Single MachineInfinite Bus (SMIB power system helps in tuning thecontrollers at one machine without considering the effect ofother machines in the power system. The effect of disturbanceseen by the machine being 100%, whereas in interconnectedpower system the effect gets distributed among differentmachines. Therefore, the controller tuning with SMIB remainsvalid for miltimachine power system as well. In this paper acomparison of PID, PSS, TCDB controllers is presentedthrough small signal stability of power system comprising ofone machine connected to infinite bus and modeled through sixK-constants. The power system components such assynchronous machine, exciter, power system stabilizer, PID,TCDB are also modeled after linearization of governingequations.

  18. Small-Signal Capacitance and Current Parameter Modeling in Large-Scale High-Frequency Graphene Field-Effect Transistors

    OpenAIRE

    Zebrev, Gennady I.; Tselykovskiy, Alexander A.; Batmanova, Daria K.; Melnik, Evgeny V.

    2011-01-01

    The analytical model of the small-signal current and capacitance characteristics of RF graphene FET is presented. The model is based on explicit distributions of chemical potential in graphene channels (including ambipolar conductivity at high source-drain bias) obtained in the framework of drift-diffusion current continuity equation solution. Small-signal transconductance and output conductance characteristics are modeled taking into account the two modes of drain current s...

  19. Resolving small signal measurements in experimental plasma environments using calibrated subtraction of noise signals.

    Science.gov (United States)

    Fimognari, P J; Demers, D R; Chen, X; Schoch, P M

    2014-11-01

    The performance of many diagnostic and control systems within fusion and other fields of research are often detrimentally affected by spurious noise signals. This is particularly true for those (such as radiation or particle detectors) working with very small signals. Common sources of radiated and conducted noise in experimental fusion environments include the plasma itself and instrumentation. The noise complicates data analysis, as illustrated by noise on signals measured with the heavy ion beam probe (HIBP) installed on the Madison Symmetric Torus. The noise is time-varying and often exceeds the secondary ion beam current (in contrast with previous applications). Analysis of the noise identifies the dominant source as photoelectric emission from the detectors induced by ultraviolet light from the plasma. This has led to the development of a calibrated subtraction technique, which largely removes the undesired temporal noise signals from data. The advantages of the technique for small signal measurement applications are demonstrated through improvements realized on HIBP fluctuation measurements. PMID:25430262

  20. ANNs in Bias Dependant Small-Signal and Noise Modeling of Microwave FETs

    Directory of Open Access Journals (Sweden)

    V. Markovi?

    2010-06-01

    Full Text Available In this paper an efficient procedure for determination of small-signal and noise behavior of microwave transistors for various bias conditions is proposed. An empirical transistor noise model based on an equivalent circuit (improvement of Pospieszalski’s noise model is considered. Since it is necessary to extract values of the model equivalent circuit for each bias point (which requires the measured data acquiring and repeated time consuming extraction procedures, it is proposed to use an artificial neural network to model the bias dependence of the equivalent circuit parameters. In that way, it is necessary to acquire the measured data and extract the equivalent circuit parameters only for several operating biases used for the network training. Once the neural network is trained, the device small-signal scattering and noise parameters are easily obtained for an arbitrary bias point from the device operating range without changes in the model. The proposed modeling approach is exemplified by modeling of a specific MESFET device in a packaged form.

  1. Research on a Small Signal Stability Region Boundary Model of the Interconnected Power System with Large-Scale Wind Power

    Directory of Open Access Journals (Sweden)

    Wenying Liu

    2015-03-01

    Full Text Available For the interconnected power system with large-scale wind power, the problem of the small signal stability has become the bottleneck of restricting the sending-out of wind power as well as the security and stability of the whole power system. Around this issue, this paper establishes a small signal stability region boundary model of the interconnected power system with large-scale wind power based on catastrophe theory, providing a new method for analyzing the small signal stability. Firstly, we analyzed the typical characteristics and the mathematic model of the interconnected power system with wind power and pointed out that conventional methods can’t directly identify the topological properties of small signal stability region boundaries. For this problem, adopting catastrophe theory, we established a small signal stability region boundary model of the interconnected power system with large-scale wind power in two-dimensional power injection space and extended it to multiple dimensions to obtain the boundary model in multidimensional power injection space. Thirdly, we analyzed qualitatively the topological property’s changes of the small signal stability region boundary caused by large-scale wind power integration. Finally, we built simulation models by DIgSILENT/PowerFactory software and the final simulation results verified the correctness and effectiveness of the proposed model.

  2. Tunable bandwidth optical rotator

    CERN Document Server

    Dimova, Emiliya; Kyoseva, Elica

    2015-01-01

    We propose and experimentally demonstrate a novel type of polarization rotator which is capable of rotating the polarization plane of a linearly polarized light at any desired angle in either broad or narrow spectral bandwidth. The rotator comprises an array of standard half-wave plates rotated at specific angles with respect to their fast-polarization axes. The performance of the rotator depends on the number of individual half-wave plates and in this paper we experimentally investigate the performance of two composite rotators comprising six and ten half-wave plates.

  3. Influence of Wind Plant Ancillary Frequency Control on System Small Signal Stability

    DEFF Research Database (Denmark)

    Su, Chi; Chen, Zhe

    2012-01-01

    Since large-scale wind farms are increasingly connected to modern power grids, the transmission system operators put more requirements as part of the grid codes on the integration of wind farms. System frequency control which is normally provided by conventional synchronous generators becomes a common requirement to wind farms. This ancillary frequency control provided by wind farms could have some influence on the system small signal stability. This paper implements an ancillary frequency control strategy on a directdrive- full-convertor-based wind farm and studies its influence on the damping ratio values of the dominant oscillation modes within the connected power system. All the calculations and simulations are conducted in DIgSILENT PowerFactory 14.0.

  4. Influence of Wind Plant Ancillary Voltage Control on System Small Signal Stability

    DEFF Research Database (Denmark)

    Su, Chi; Chen, Zhe

    2012-01-01

    As a common tendency, large-scale wind farms are increasingly connected to the transmission system of modern power grids. This introduces some new challenges to the connected power systems, and the transmission system operators (TSOs) have to put some new requirements as part of the grid codes on the integration of wind farms. One common requirement to wind farms is the function of system voltage control which can be implemented in the grid-side convertor controller of a variable speed wind turbine. This ancillary voltage control provided by wind farms could have some influence on the system small signal stability. This paper implements an ancillary voltage control strategy on a direct-drive-full-convertor-based wind farm and studies its influence on the damping ratio values of the dominant oscillation mode within the connected power system. All the calculations and simulations are conducted in DIgSILENT PowerFactory 14.0.

  5. A small-signal generator based on a multi-layer graphene/molybdenum disulfide heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Zhen; Tian, He; Feng, Tingting; Zhao, Lianfeng; Xie, Dan; Yang, Yi; Xiao, Lei; Wang, Jing; Ren, Tian-Ling, E-mail: RenTL@tsinghua.edu.cn, E-mail: JunXu@tsinghua.edu.cn; Xu, Jun, E-mail: RenTL@tsinghua.edu.cn, E-mail: JunXu@tsinghua.edu.cn [Institute of Microelectronics, Tsinghua University, Beijing 100084, China and Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084 (China)

    2013-12-23

    In this work, we fabricate a heterojunction small-signal generator (HSSG) based on a graphene-molybdenum disulfide (MoS{sub 2}) heterojunction. The HSSG is fundamentally different from any analog device developed previously. The HSSG is composed of two quasi-2D heterojunctions and has three terminals named injector (I), recombinator (R), and generator (G). MoS{sub 2} serves as I and G, and graphene works as R in the HSSG. The scale coefficient (??=?I{sub G}/I{sub R}) of the HSSG is 1.14?×?10{sup ?4} (V{sub IG,?IR}?=?0.2?V) to 1.95?×?10{sup ?4} (V{sub IG,?IR}?=?1?V). The current generated from G could be as low as pA scale, which reveals the good performance of the HSSG.

  6. Wide-Area Assessment of Aperiodic Small Signal Rotor Angle Stability in Real-Time

    DEFF Research Database (Denmark)

    Jóhannsson, Hjörtur; Nielsen, Arne Hejde

    2014-01-01

    This paper presents the details of a new real-time stability assessment method. The method assesses a particular mechanism of stability: each generator's capability to generate sufficient steady state electromechanical torque. The lack of sufficient steady state torque causes aperiodic increase in rotor angle and a loss of synchronism, referred to as aperiodic small signal instability. The paper provides the theoretical background of the method and an analytical assessment criterion. Furthermore, a mathematical mapping of the generators' operating points that enables informative visualization of multiple operating points is derived in the paper. Finally, results from timedomain simulation of instability scenarios in the Nordic32 test system are presented and results used for testing the assessment method. The results illustrate the method's capability to efficiently identify the location of the emerging problem and to quantify margins to stability boundary.

  7. A small-signal generator based on a multi-layer graphene/molybdenum disulfide heterojunction

    International Nuclear Information System (INIS)

    In this work, we fabricate a heterojunction small-signal generator (HSSG) based on a graphene-molybdenum disulfide (MoS2) heterojunction. The HSSG is fundamentally different from any analog device developed previously. The HSSG is composed of two quasi-2D heterojunctions and has three terminals named injector (I), recombinator (R), and generator (G). MoS2 serves as I and G, and graphene works as R in the HSSG. The scale coefficient (??=?IG/IR) of the HSSG is 1.14?×?10?4 (VIG,?IR?=?0.2?V) to 1.95?×?10?4 (VIG,?IR?=?1?V). The current generated from G could be as low as pA scale, which reveals the good performance of the HSSG

  8. A New Current-Controlled-Power Technique for Small Signal Applications

    Directory of Open Access Journals (Sweden)

    Adisak Monpapassorn

    2012-04-01

    Full Text Available In this paper, a new current-controlled-power technique for small signal applications is presented. The proposed technique needs no passive devices (a resistor and a capacitor but the well-known SCR technique needs, thus the proposed technique is very suitable for an IC process. An example application as a new current-controlled-power CMOS fullwave rectifier is also given. The example application is simulated by using the SPICE program. Simulation results show that the proposed technique can work well; the controlled-current from 0 µA to 5.5 µA produces the peak area amplitude from 100 mV to 0 mV to the load.

  9. External-Noise-Induced Small-Signal Detection with Solution-Gated Carbon Nanotube Transistor

    Science.gov (United States)

    Hakamata, Yasufumi; Ohno, Yasuhide; Maehashi, Kenzo; Inoue, Koichi; Matsumoto, Kazuhiko

    2011-04-01

    A solution-gated carbon nanotube field-effect transistor (CNTFET) based on stochastic resonance (SR) was investigated in order to enhance small-signal detection under ambient noise conditions. When noise of optimal intensity was introduced at the reference electrode in a nonlinear CNTFET, the electric double layer in the solution was modulated, resulting in SR behavior. Moreover, when the CNTFET was used as a pH sensor, high sensitivity was achieved, which enabled the detection of small differences in pH. The best results were obtained in a noisy environment; therefore, a solution-gated SR-based CNTFET operated in the subthreshold regime is a promising high-sensitivity sensor.

  10. Comparison Study of Power System Small Signal Stability Improvement Using SSSC and STATCOM

    DEFF Research Database (Denmark)

    Hu, Weihao; Su, Chi

    2013-01-01

    A static synchronous series compensator (SSSC) has the ability to emulate a reactance in series with the connected transmission line. A static synchronous compensator (STATCOM) is able to provide the reactive power to an electricity network. When fed with some supplementary signals from the connected power system, both SSSC and STATCOM are able to participate in the power system inter-area oscillation damping by changing the compensated reactance or the provided reactive power. This paper analyses the influence of SSSC and STATCOM on power system small signal stability. The damping controller schemes for SSSC and STATCOM are presented and discussed. The IEEE 39-bus New England system model as the test system is built in DIgSIELNT PowerFactory, in which the damping control strategies for both SSSC and STATCOM are validated by time domain simulations and modal analysis. Furthermore, comparison studies show that the SSSC is a better solution in term of equipment capabilities and costs.

  11. Bandwidth enhancement of Fabry-Perot quantum-well lasers by injection-locking

    Science.gov (United States)

    Jin, Xiaomin; Chuang, Shun-Lien

    2006-06-01

    Theory and experiment for dc and small-signal electrical modulation of an injection-locked quantum-well (QW) Fabry-Perot laser are presented. Our experiment is realized by performing side-mode injection locking of a multiple-quantum-well (MQW) InGaAsP Fabry-Perot (FP) laser, which has the advantage of optical wavelength conversion. We first measure the dc characteristics and optical spectra of an injection-locked laser to define its locking range and linewidth enhancement factor. We then show experimentally that the bandwidth of an injection-locked semiconductor laser is 10.5 GHz, which is around twice the free-running electrical modulation bandwidth (5.3 GHz). The relaxation frequency of the injection-locked laser can be 3.5 times greater than the free-running value. Our theoretical model includes mode competition, gain saturation, low frequency roll-off, and optical confinement factor of the QW structure. The theory shows good agreement with our experimental results. We point out that the small-signal modulation of injection-locked lasers still suffers severely from low frequency roll-off, which comes from the carrier transport effect and parasitic effect of the bias circuit. If we can reduce those effects, the modulation bandwidth can be further increased to 15 GHz, which is around 3 times of the free-running value.

  12. Wide Area Prosumption Control and Sensitivities of Aperiodic Small Signal Stability Indicators

    DEFF Research Database (Denmark)

    Wittrock, Martin Lindholm; Jóhannsson, Hjörtur

    2014-01-01

    This paper introduces the concept of prosumption control where intelligent loads and distributed generation are aggregated and controlled to improve power system security. It is expected that intelligent load and generation units can respond to control / market signals and thus present an opportunity of available resources for changing the operating point (OP) of a system to one that is more secure. A prosumption pattern is then a signal to prosumers to shift their demand in time. This makes it possible to temporarily change the distribution of the power demand. A prosumption pattern is balanced, such that frequency can be maintained by other smart grid technologies. To find a prosumption pattern which can improve security, it is necessary to determine sensitivities of stability indicators such that beneficial load permutations can be identified. After introducing prosumption control and patterns, stability indicators for aperiodic small signal angular stability (ASSA) are examined, while the concept of prosumption is described. The methodology presented is shown to be able to assess the margin to instability and to predict how this margin can be affected if a load is changed in the grid. The resulting sensitivities are described and their suitability to be used to search for a prosumption pattern is evaluated.

  13. Small signal thermal analysis of local multibarrier behaviour in SiC Schottky diodes

    International Nuclear Information System (INIS)

    A nickel-based silicon carbide Schottky barrier diode presenting multibarrier behaviour was inspected by Small sIgnal Modulation for Thermal Analysis (SIMTA) to detect the weak spots responsible for this behaviour. SIMTA thermally modulates in frequency such weak spots with a small signal voltage while the device is electrically biased in an operating point of its static I/V curve (20 A–1 kV capability). This allows for quantitative studying of them in a thermal steady state as heat sources by lock-in thermography depending on the device operating regime. Using SIMTA, the barrier height and the area of each weak spot were determined by thermal means, yielding to an electrical model that fits the observed multibarrier behaviour. Results suggest that these spots were caused by surface areas of high density of states (due to 3C–SiC stacking faults) created during the wire bonding process, which locally shifted the Schottky barrier due to Fermi level pinning. Their origin was confirmed by scanning electron microscope inspections after milling these locations with a focused on beam, detecting Schottky metal contact degradation at weak spot locations due to an excessive bonding pressure. (paper)

  14. A methodology for performance evaluation of LEDs based on ac small signal analysis

    Scientific Electronic Library Online (English)

    Isnaldo J. Souza, Coêlho; James N. da, Silva.

    2013-12-01

    Full Text Available This paper shows fundamentals and results that support a promising methodology for evaluation in locus of a LED from its own radiating signal, and that allows monitoring of its aging by remote inference on which degradation mechanism is acting internally to the device's structure. It brings out also [...] an alternative route for estimation of parameters of the Shockley's equation directly from small-signal ac analysis in a simple bench circuit. This last approach is shown to be effective and advantageous relatively to methods which take near a hundred points to achieve good estimations, while it uses only two points of the I-V static characteristic. Both approaches __ referred to as remote inference method (RIM) and two-points method (TPM) __ are applied together to show that external quantum efficiency (EQE) can be closely correlated to the injection process assumed to take place in that emitting device, meanwhile overvalued serial resistances due to neutral layers and ohmic contacts in electrodes affect only its electrical performance.

  15. A Three-Dimensional Model of Small Signal Free-Electron Lasers

    OpenAIRE

    Webb, Stephen; Wang, Gang; Litvinenko, Vladimir

    2011-01-01

    Coherent electron cooling is an ultra-high-bandwidth form of stochastic cooling which utilizes the charge perturbation from Debye screening as a seed for a free-electron laser. The amplified and frequency-modulated signal that results from the free-electron laser process is then used to give an energy-dependent kick on the hadrons in a bunch. In this paper, we present a theoretical description of a high-gain free-electron laser with applications to a complete theoretical des...

  16. A Three-Dimensional Model of Small Signal Free-Electron Lasers

    CERN Document Server

    Webb, Stephen; Litvinenko, Vladimir

    2011-01-01

    Coherent electron cooling is an ultra-high-bandwidth form of stochastic cooling which utilizes the charge perturbation from Debye screening as a seed for a free-electron laser. The amplified and frequency-modulated signal that results from the free-electron laser process is then used to give an energy-dependent kick on the hadrons in a bunch. In this paper, we present a theoretical description of a high-gain free-electron laser with applications to a complete theoretical description of coherent electron cooling.

  17. On estimation of instantaneous bandwidth

    OpenAIRE

    Ristic, B.; Boashash, B.

    1996-01-01

    This paper is a reminder that any measure of instantaneous frequency of a signal in practice should be accompanied by a measure of its spectral spread or instantaneous bandwidth, and it investigates three approaches to instantaneous bandwidth estimation. (Additional details can be found in the comprehensive book on Time-Frequency Signal Analysis and Processing (see http://www.elsevier.com/locate/isbn/0080443354). In addition, the most recent upgrade of the original software package tha...

  18. Improvement of modulation bandwidth in multisection RSOA for colorless WDM-PON.

    Science.gov (United States)

    Kim, Hyun-Soo; Choi, Byung-Seok; Kim, Ki-Soo; Kim, Dong Churl; Kwon, O-Kyun; Oh, Dae-Kon

    2009-09-14

    We demonstrated two-section reflective semiconductor optical amplifier (RSOA) with dramatic improvement of small-signal modulation bandwidth above 10 GHz as colorless source for wavelength division multiplexed-passive optical network (WDM-PON). The device provides the fiber-to-fiber gain of 22.8 dB, 3-dB amplified spontaneous emission (ASE) bandwidth of 30 nm, and ripple of 1.5 dB. Good performance at 2.5 Gbps was obtained with an extinction ratio of 8 dB and a power penalty of 2 dB at a 10(-9) bit error rate (BER) up to 20 km transmission. PMID:19770850

  19. 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.

  20. Reduction of electromagnetic interference susceptibility in small-signal analog circuits using complementary split-ring resonators

    OpenAIRE

    Pe?rez Robles, Daniel; Gil Gali?, Ignacio; Gago Barrio, Javier; Ferna?ndez Garci?a, Rau?l; Balcells Sendra, Josep; Gonza?lez Di?ez, David; Berbel Artal, Ne?stor; Mon Gonza?lez, Juan

    2012-01-01

    Low-frequency analog and digital electronic circuits are susceptible to electromagnetic interference in the radiofrequency (RF) range. This disturbance is produced when the coupled RF signal is rectified by the nonlinear behavior of the semiconductors used in the small-signal analog input stage of the electronic system. Circuits based on operational amplifiers are usually employed for such input stages. These circuits present an amplitude modulation demodulation produced ...

  1. Gain and noise properties of small-signal erbium-doped fiber amplifiers pumped in the 980-nm band

    DEFF Research Database (Denmark)

    Pedersen, B.; Chirravuri, J.

    1992-01-01

    The authors have experimentally and theoretically investigated the effects of detuning the pump wavelength on the gain and noise properties of small-signal, erbium-doped fiber amplifiers codirectionally pumped in the 980-nm band. While the pump wavelength can be varied over a wide range with little impact on the gain, a noise penalty is incurred. For amplifiers saturated by amplified spontaneous emission, it is possible to increase the gain by detuning the pump wavelength

  2. 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.

  3. Dynamic bandwidth allocation in GPON networks

    DEFF Research Database (Denmark)

    Ozimkiewiez, J.; Ruepp, Sarah Renée

    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 allocation. Results show that the status reporting is more efficiently using the bandwidth while non-status reporting provides better QoS for real time services.

  4. Fade depth scaling with channel bandwidth

    OpenAIRE

    Malik, Wq; Allen, B.; Edwards, Dj

    2007-01-01

    The dependence of small-scale fading on bandwidth is quantified experimentally in the 3.1-10.6GHz band for indoor channels. The fade depth converges to 4dB at 1GHz bandwidth, with little reduction for further increase in bandwidth. A simple yet accurate empirical fade depth model is developed, enabling convenient evaluation of the link budget for a channel with given bandwidth.

  5. On the wide-range bias dependence of transistor d.c. and small-signal current gain factors.

    Science.gov (United States)

    Schmidt, P.; Das, M. B.

    1972-01-01

    Critical reappraisal of the bias dependence of the dc and small-signal ac current gain factors of planar bipolar transistors over a wide range of currents. This is based on a straightforward consideration of the three basic components of the dc base current arising due to emitter-to-base injected minority carrier transport, base-to-emitter carrier injection, and emitter-base surface depletion layer recombination effects. Experimental results on representative n-p-n and p-n-p silicon devices are given which support most of the analytical findings.

  6. Retaining Bandwidth Efficiency and Efficacy

    OpenAIRE

    Timo Meynhardt; Camillo Von Müller

    2012-01-01

    In this paper we examine how the notion of systemic relevance challenges bandwidth efficiency and efficacy of middle managers of financial service organizations and what managers can do to coop with increasingly complex environments of the firm. As the envisaged merger of The New York Stock Exchange (NYSE Euronext) with Deutsche Börse Group is revitalizing debates concerning institutional configurations of stock markets, we first ask how managers of one of the world’s leading stock exchang...

  7. Bivariate Instantaneous Frequency and Bandwidth

    OpenAIRE

    Lilly, Jonathan M.; Olhede, Sofia C.

    2009-01-01

    The generalizations of instantaneous frequency and instantaneous bandwidth to a bivariate signal are derived. These are uniquely defined whether the signal is represented as a pair of real-valued signals, or as one analytic and one anti-analytic signal. A nonstationary but oscillatory bivariate signal has a natural representation as an ellipse whose properties evolve in time, and this representation provides a simple geometric interpretation for the bivariate instantaneous m...

  8. Image Scrambling without Bandwidth Expansion

    OpenAIRE

    Van De Ville, D.; Philips, W.; Van de Walle, R.; Lemahieu, I.

    2004-01-01

    Image-scrambling schemes are designed to render the image content unintelligible. Wyner has proposed an elegant one-dimensional (1-D) scrambling scheme without bandwidth expansion, making use of the discrete prolate spheroidal sequences (DPSS). The DPSS are optimal regarding their energy concentration in a given frequency subband. In this paper, we propose the two-dimensional (2-D) extension and application of this algorithm. We discuss new possibilities introduced by the 2-D approach. We als...

  9. Design Of Power System Stabilizer To Improve Small Signal Stability By Using Modified Heffron-Phillip’s Model

    Directory of Open Access Journals (Sweden)

    G. Sai Sudheer,

    2011-06-01

    Full Text Available One of the major problems in power system operation is related to small signal instability caused by insufficient damping in the system. The most effective way of countering this instability is to use auxiliary controllers called Power System Stabilizers, to produce additional damping in the system. Generally Heffron-phillip’s Model of a synchronous machine is commonly used for the small signal stability analysis. A Modified Heffron-Phillip’s (KconstantModel is derived for the design of Power System Stabilizers; knowledge of external parameters, such as equivalent infinite bus voltage and external impedance value are required for designing a conventional power system stabilizer, Modified Heffron-Phillip’s Model power system stabilizer. The efficiency of the proposeddesign technique and the performance of the stabilizer has been evaluated over a range of operating and system conditions and the performance of the proposed Modified Heffron-Phillip’s Model is much better than the conventional power system stabilize.. The proposed work describes the ‘Design of Power System Stabilizer by using Modified Heffron-Phillip’s model’ is simulated by using MATLAB/SIMULINK.

  10. Optimization and small-signal modeling of zero-bias InAs self-switching diode detectors

    Science.gov (United States)

    Westlund, A.; Sangaré, P.; Ducournau, G.; Iñiguez-de-la-Torre, I.; Nilsson, P.-Å.; Gaquière, C.; Desplanque, L.; Wallart, X.; Millithaler, J. F.; González, T.; Mateos, J.; Grahn, J.

    2015-02-01

    Design optimization of the InAs self-switching diode (SSD) intended for direct zero-bias THz detection is presented. The SSD, which consists of nanometer-sized channels in parallel, was described using an equivalent small-signal circuit. Expressions for voltage responsivity and noise equivalent power (NEP) were derived in terms of geometrical design parameters of the SSD, i.e. the channel length and the number of channels. Modeled design dependencies were confirmed by RF and DC measurements on InAs SSDs. In terms of NEP, an optimum number of channels were found with the detector driven by a 50 ? source. With a matched source, the model predicted a responsivity of 1900 V/W and NEP of 7.7 pW/Hz½ for a single-channel InAs SSD with 35 nm channel width. Monte Carlo device simulations supported observed design dependencies. The proposed small-signal model can be used to optimize SSDs of any material system for low-noise and high-frequency operation as zero-bias detectors. In large signal measurements, the responsivity of the InAs SSDs exhibited a 1 dB deviation from linear responsivity at an input power of -3 dBm from a 50 ? source.

  11. Improvements to the extraction of an AlGaN/GaN HEMT small-signal model

    International Nuclear Information System (INIS)

    The accurate extraction of AlGaN/GaN HEMT small-signal models, which is an important step in large-signal modeling, can exactly reflect the microwave performance of the physical structure of the device. A new method of extracting the parasitic elements is presented, and an open dummy structure is introduced to obtain the parasitic capacitances. With a Schottky resistor in the gate, a new method is developed to extract Rg. In order to characterize the changes of the depletion region under various drain voltages, the drain delay factor is involved in the output conductance of the device. Compared to the traditional method, the fitting of S 11 and S 22 is improved, and fT and fmax can be better predicted. The validity of the proposed method is verified with excellent correlation between the measured and simulated S-parameters in the range of 0.1 to 26.1 GHz. (semiconductor devices)

  12. Effects of Random Circuit Fabrication Errors on Small Signal Gain and on Output Phase In a Traveling Wave Tube

    Science.gov (United States)

    Rittersdorf, I. M.; Antonsen, T. M., Jr.; Chernin, D.; Lau, Y. Y.

    2011-10-01

    Random fabrication errors may have detrimental effects on the performance of traveling-wave tubes (TWTs) of all types. A new scaling law for the modification in the average small signal gain and in the output phase is derived from the third order ordinary differential equation that governs the forward wave interaction in a TWT in the presence of random error that is distributed along the axis of the tube. Analytical results compare favorably with numerical results, in both gain and phase modifications as a result of random error in the phase velocity of the slow wave circuit. Results on the effect of the reverse-propagating circuit mode will be reported. This work supported by AFOSR, ONR, L-3 Communications Electron Devices, and Northrop Grumman Corporation.

  13. Small-Signal Analysis of Autonomous Hybrid Distributed Generation Systems in Presence of Ultracapacitor and Tie-Line Operation

    Science.gov (United States)

    Ray, Prakash K.; Mohanty, Soumya R.; Kishor, Nand

    2010-07-01

    This paper presents small-signal analysis of isolated as well as interconnected autonomous hybrid distributed generation system for sudden variation in load demand, wind speed and solar radiation. The hybrid systems comprise of different renewable energy resources such as wind, photovoltaic (PV) fuel cell (FC) and diesel engine generator (DEG) along with the energy storage devices such as flywheel energy storage system (FESS) and battery energy storage system (BESS). Further ultracapacitors (UC) as an alternative energy storage element and interconnection of hybrid systems through tie-line is incorporated into the system for improved performance. A comparative assessment of deviation of frequency profile for different hybrid systems in the presence of different storage system combinations is carried out graphically as well as in terms of the performance index (PI), ie integral square error (ISE). Both qualitative and quantitative analysis reflects the improvements of the deviation in frequency profiles in the presence of the ultracapacitors (UC) as compared to other energy storage elements.

  14. Small-Signal Modeling, Analysis and Testing of Parallel Three-Phase-Inverters with A Novel Autonomous Current Sharing Controller

    DEFF Research Database (Denmark)

    Guan, Yajuan; Quintero, Juan Carlos Vasquez

    2015-01-01

    A novel simple and effective autonomous currentsharing controller for parallel three-phase inverters is employed in this paper. The novel controller is able to endow to the system high speed response and precision in contrast to the conventional droop control as it does not require calculating any active or reactive power, instead it uses a virtual impedance loop and a SFR phase-locked loop. The small-signal model of the system was developed for the autonomous operation of inverter-based microgrid with the proposed controller. The developed model shows large stability margin and fast transient response of the system. This model can help identifying the origin of each of the modes and possible feedback signals for design of controllers to improve the system stability. Experimental results from two parallel 2.2 kVA inverters verify the effectiveness of the novel control approach.

  15. Small-signal model parameter extraction for microwave SiGe HBTs based on Y- and Z-parameter characterization

    International Nuclear Information System (INIS)

    High frequency intrinsic small-signal model parameter extraction for microwave SiGe heterojunction bipolar transistors is studied, with a focus on the main feedback elements including the emitter series resistor, internal and external base-collector capacitors as well as the base series resistor, all of which are important in determining the behavior of the device equivalent circuit. In accordance with the respective features of definition of the Y- and Z-parameters, a novel combined use of them succeeds in reasonably simplifying the device equivalent circuit and thus decoupling the extraction of base-collector capacitances from other model parameters. As a result, a very simple direct extraction method is proposed. The proposed method is applied for determining the SiGe HBT small-signal model parameters by taking numerically simulated Y- and Z-parameters as nominal 'measurement data' with the help of a Taurus-device simulator. The validity of the method is preliminarily confirmed by the observation of certain linear relations of device frequency behavior as predicted by the corresponding theoretical analysis. Furthermore, the extraction results can be used to reasonably account for the dependence of the extracted model parameters on device geometry and process parameters, reflecting the explicit physical meanings of parameters, and especially revealing the distributed nature of the base series resistor and its complex interactions with base-collector capacitors. Finations with base-collector capacitors. Finally, the accuracy of our model parameter extraction method is further validated by comparing the modeled and simulated S-parameters as a function of frequency. (semiconductor devices)

  16. 47 CFR 2.202 - Bandwidths.

    Science.gov (United States)

    2010-10-01

    ...depending on the quality desired Speech and music, M=4000, Bandwidth: 8000 Hz= 8 kHz...depending on the quality desired Speech and music, M=4000, Bandwidth: 4000 Hz= 4 kHz...lowest modulation frequency Speech and music, M=4500, lowest modulation...

  17. 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…

  18. 47 CFR 24.131 - Authorized bandwidth.

    Science.gov (United States)

    2010-10-01

    ...CONTINUED) COMMON CARRIER SERVICES PERSONAL COMMUNICATIONS SERVICES Narrowband PCS § 24.131 Authorized bandwidth. The authorized bandwidth of narrowband PCS channels will be 10 kHz for 12.5 kHz channels and 45 kHz for 50 kHz channels....

  19. Design and characterization of a 30-GHz bandwidth low-power silicon traveling-wave modulator

    Science.gov (United States)

    Ding, Ran; Liu, Yang; Li, Qi; Yang, Yisu; Ma, Yangjin; Padmaraju, Kishore; Lim, Andy Eu-Jin; Lo, Guo-Qiang; Bergman, Keren; Baehr-Jones, Tom; Hochberg, Michael

    2014-06-01

    We present the design and characterization of a silicon PN junction traveling-wave Mach-Zehnder modulator near 1550 nm wavelength. The device shows 30 GHz bandwidth at 1 V reverse bias, with a 2.7 V-cm V?L? and accordingly a 9-V small-signal V?. The insertion loss of the phase shifter is 3.6 dB±0.4 dB. The device performance metrics in combination show significant improvement compared to the state-of-the-art in the sense that lower phase shifter loss and higher bandwidth are achieved for the same V? or vice versa. We demonstrated low modulation power of 640-fJ/bit at 40 Gb/s with a 1.6-Vpp differential-drive and 0-V DC bias, raising the prospect of direct compatibility with CMOS drive-voltages. Critical design tradeoffs are analyzed and design models are validated with measurement results. We proposed a new figure-of-merit (FOM) V?L?RpnC2pn as the junction design merit for high-speed traveling-wave modulators, and utilized 6 implants to achieve an optimal FOM with lower insertion loss. Several key RF design issues are addressed for the first time using simulation and measurement results. In particular, we discussed bandwidth extension using mismatched termination and closely matched experimental results. A bandwidth-limiting RF multi-mode behavior is noted, which also exists in other results in the literature; we suggested a widely applicable design remedy.

  20. Small signal audio design

    CERN Document Server

    Self, Douglas

    2014-01-01

    Learn to use inexpensive and readily available parts to obtain state-of-the-art performance in all the vital parameters of noise, distortion, crosstalk and so on. With ample coverage of preamplifiers and mixers and a new chapter on headphone amplifiers, this practical handbook provides an extensive repertoire of circuits that can be put together to make almost any type of audio system.A resource packed full of valuable information, with virtually every page revealing nuggets of specialized knowledge not found elsewhere. Essential points of theory that bear on practical performance are lucidly

  1. Characterization of small-signal intensity modulation of single-mode fiber grating Fabry-Perot laser source

    Science.gov (United States)

    Hisham, Hisham Kadhum; Abas, Ahmad Fauzi; Mahdiraji, Ghafour Amouzad; Mahdi, Mohd Adzir; Noor, Ahmad Shukri Muhammad

    2012-03-01

    A comprehensive study on the small-signal intensity modulation (IM) characteristics of a fiber grating Fabry-Perot (FGFP) laser is numerically investigated. The effect of external optical feedback (OFB), temperature, injection current, cavity volume, nonlinear gain compression factor, and fiber grating (FG) parameters on IM characteristics are presented. The temperature dependence (TD) of IM is calculated according to the TD of laser cavity parameters instead of using the well-known Parkove relationship. It has been shown that the optimum external fiber length ( L ext) is 3.1 cm. The optimum range of working temperature for FGFP laser is between 23 to 27 °C. We also show that by increasing the laser injection current from 10 to 60 mA, the IM peak amplitude decreased from 6.3 to 0.2 dB and the relaxation-oscillation frequency (ROF) is shifted from 1.2 GHz towards higher frequency of 5.48 GHz. In addition, the AR coating reflectivity and gain compression factor have no significant effect on the IM. The study indicates that a stable operation and excellent modulation characteristic can be obtained after optimization process.

  2. High-Bandwidth Hybrid Sensor (HYSENS) Project

    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...

  3. Ultrawide Bandwidth RFID: The Next Generation?

    OpenAIRE

    Dardari, Davide; D Errico, Raffaele; Roblin, Christophe; Sibille, Alain; Moe Z. Win

    2010-01-01

    Future advanced radio-frequency identification (RFID) systems are expected to provide both identification and high-definition localization of objects with improved reliability and security while maintaining low power consumption and cost. Ultrawide bandwidth (UWB) technology is a promising solution for next generation RFID systems to overcome most of the limitations of the current narrow bandwidth RFID technology such as: reduced area coverage, insufficient ranging resolution for accurate loc...

  4. Increase Bandwidth for Circular Microstrip Patch Antenna

    OpenAIRE

    Sonali Jain,; Rajesh Nema,

    2012-01-01

    In this paper a design and performance of acircularly microstrip patch antenna, for the application inWireless Local Area Network (WLAN), are reported here. Theantenna is a proximity coupled microstrip patch antenna wherethe radiating patch is loadedby a V-slot. This miniaturizedmicrostrip antenna has wide bandwidth in the frequency bandof WLAN and exhibits circularly far field with very good axialratio bandwidth. The simulated results using IE3D software areverified by measurement

  5. Bandwidth Analysis of Smart Meter Network Infrastructure

    DEFF Research Database (Denmark)

    Balachandran, Kardi; Olsen, Rasmus LØvenstein

    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 of the bandwidth requirements are analysed. For this analysis the assumptions and limitations are defined. The results obtained by the analysis show, that the amount of data collected and transferred by a smart meter is very low compared to the available bandwidth of most internet connections. The results show the bandwidth provided by GPRS technology is sufficient. However, from a delay point of view, GPRS has its limits, therefore, xDSL or 3G can be used for faster transfer but will rarely utilize the available bandwidth from these technologies. The aggregator or concentrator which is responsible to collect all the data from the different smart meters can become a bottleneck as the aggregated amount of data is high, thus the bandwidth for the data concentrator has to be high. These results are interesting to look at as it is a common misunderstanding that smart grid service requires high bandwidth.

  6. InGaAs/AlGaInAs/InP Laser with Compressively Strained Multiquantum Well Layers for High Speed Modulation Bandwidth

    Scientific Electronic Library Online (English)

    M.T., Furtado; E.J.T., Manganote; A.C.G., Bordeaux-Rêgo; F., Steinhagen; H., Janning; H., Burkhard.

    1997-12-01

    Full Text Available The modulation frequency response of compressively strained multiquantum well (MQW) lasers grown with an InGaAs/AlGaInAs/InP heterostructure and emitting at the wavelength of 1.55 mm is presented. The laser devices processed with the mushroom-stripe buried structure presen [...] t a high frequency 3 dB bandwidth above 20 GHz. The frequency response was measured with the small signal modulation technique. The logarithmic subtraction method was employed to extract the intrisic frequency response of the MQW active layer, providing the determination of important laser parameters: the differential gain, the nonlinear gain coefficient and the maximum 3 dB frequency bandwidth.

  7. Development and Implementation of the Nordic Grid Model for Power System Small-Signal and Transient Stability Studies in a Free and Open Source Software

    OpenAIRE

    Chompoobutrgool, Yuwa; Li, Wei; Vanfretti, Luigi

    2012-01-01

    This article presents an implementation of a Nordic grid model in Power System Analysis Toolbox (PSAT) -a free and open-source software. A newly developed hydro turbine and hydro governor (HTG) model is implemented with this grid model and compared with the currently available PSAT turbine and governor models. Small-signal and transient stability analyses of the system using the two models are carried out and compared to demonstrate the difference and necessity of accurate hydro turbine and g...

  8. Hand acceleration impulse bandwidth during target acquisition: Implications for teleoperators bandwidth requirements

    International Nuclear Information System (INIS)

    The purpose of this experiment was to provide data about bandwidth requirements for teleoperators. During teleoperation, user inputs are changes in forces applied to the master controller arising from changes in hand acceleration during execution of goal-directed trajectories, so human hand acceleration bandwidth sets an upper bound on teleoperator feedforward bandwidth requirements. Participants completed a set of computerized target acquisition tasks using a mouse, and the computer recorded the cursor trajectory. Movement time, positioning error, the number of acceleration-deceleration impulses, impulse band-width, impulse amplitude, and impulse period were calculated from the trajectory trace. As many as 6 acceleration-deceleration impulses occurred during a single target acquisition, but in most trials (96.8%) there were 4 or fewer. The average acceleration-deceleration impulse bandwidth was 5.63 Hz for the first impulse and 9.20 Hz for subsequent impulses. The average period was 265 ms (3.77 Hz) for the first impulse and 218 ms (4.59 Hz) for succeeding ones. Therefore, to completely capture hand trajectories, master controllers and slave arms must have acceleration bandwidth higher than 9.20 Hz. However, it may be that only the joints closest to the end-effector need to accommodate the highest bandwidths and ''shoulder '' joints may only need to accommodate 5.63 Hz acceleration bandwidth

  9. Ultra-Wide bandwidth Circular Monopole Antenna

    Directory of Open Access Journals (Sweden)

    Shashwat Chaturvedi

    2012-08-01

    Full Text Available In this paper, a novel circular monopole Antenna for Ultra-Wideband application with corner-shaped ground plane is presented and discussed. It is printed on a dielectric substrate and fed by a 50 ohm microstrip line; a planar circular disc monopole has been demonstrated to provide an ultra wide 10 dB return loss bandwidth. The proposed design offers low profile, ultra high bandwidth and compact antenna element. This design offers the improved gain and directivity of antenna which is applied for high efficiency antenna. The maximum bandwidth from 1.30 GHz to 12GHz for voltage standing wave ratio (VSWR < 2 and the peak antenna gain is 4dB to 9 dB.

  10. Improved space bandwidth product in image upconversion

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin; Pedersen, Christian

    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 (?k=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.

  11. Kernel bandwidth estimation for nonparametric modeling.

    Science.gov (United States)

    Bors, Adrian G; Nasios, Nikolaos

    2009-12-01

    Kernel density estimation is a nonparametric procedure for probability density modeling, which has found several applications in various fields. The smoothness and modeling ability of the functional approximation are controlled by the kernel bandwidth. In this paper, we describe a Bayesian estimation method for finding the bandwidth from a given data set. The proposed bandwidth estimation method is applied in three different computational-intelligence methods that rely on kernel density estimation: 1) scale space; 2) mean shift; and 3) quantum clustering. The third method is a novel approach that relies on the principles of quantum mechanics. This method is based on the analogy between data samples and quantum particles and uses the SchrOdinger potential as a cost function. The proposed methodology is used for blind-source separation of modulated signals and for terrain segmentation based on topography information. PMID:19546043

  12. Bypassing the bandwidth theorem with PT symmetry

    Science.gov (United States)

    Ramezani, Hamidreza; Schindler, J.; Ellis, F. M.; Günther, Uwe; Kottos, Tsampikos

    2012-06-01

    The beat time ?fpt associated with the energy transfer between two coupled oscillators is dictated by the bandwidth theorem which sets a lower bound ?fpt˜1/??. We show, both experimentally and theoretically, that two coupled active LRC electrical oscillators with parity-time (PT) symmetry bypass the lower bound imposed by the bandwidth theorem, reducing the beat time to zero while retaining a real valued spectrum and fixed eigenfrequency difference ??. Our results foster design strategies which lead to (stable) pseudounitary wave evolution, and may allow for ultrafast computation, telecommunication, and signal processing.

  13. Bypassing the bandwidth theorem with PT symmetry

    CERN Document Server

    Ramezani, Hamidreza; Ellis, F M; Guenther, Uwe; Kottos, Tsampikos

    2012-01-01

    The beat time {\\tau}_{fpt} associated with the energy transfer between two coupled oscillators is dictated by the bandwidth theorem which sets a lower bound {\\tau}_{fpt}\\sim 1/{\\delta}{\\omega}. We show, both experimentally and theoretically, that two coupled active LRC electrical oscillators with parity-time (PT) symmetry, bypass the lower bound imposed by the bandwidth theorem, reducing the beat time to zero while retaining a real valued spectrum and fixed eigenfrequency difference {\\delta}{\\omega}. Our results foster new design strategies which lead to (stable) pseudo-unitary wave evolution, and may allow for ultrafast computation, telecommunication, and signal processing.

  14. An EC-branch in the decay of 27-s sup 2 sup 6 sup 3 Db evidence for the isotope sup 2 sup 6 sup 3 Rf

    CERN Document Server

    Kratz, J V; Rieth, U; Kronenberg, A K; Kuczewski, B; Strub, E; Brüchle, W; Schädel, M; Schausten, B; Türler, A; Gäggeler, H W; Jost, D T; Gregorich, K E; Nitsche, H; Laue, C; Sudowe, R; Wilk, P A

    2003-01-01

    27-s sup 2 sup 6 sup 3 Db was produced in the sup 2 sup 4 sup 9 Bk ( sup 1 sup 8 O, 4n) reaction at 93 MeV.The activity was transported by a He/KCl-jet to the laboratory where it was collected for 15 min and then subjected to a chemical separation specific for group-4 elements. The activity was dissolved in 0.5 M unbuffered alpha-HiB and eluted from a cation-exchange column. The effluent was made 9 M in HCl and group-4 tetrachlorides were extracted into TBP/Cyclohexane which was evaporated to dryness on a Ta disc. The Ta discs were assayed for alpha and SF activity. A SF activity with a half life on the order of 20 min was observed and assigned to the nuclide sup 2 sup 6 sup 3 Rf. It is formed by electron-capture decay of sup 2 sup 6 sup 3 Db with a decay branch of 3 sup + sup 4 sub - sub 1 %.

  15. Bandwidth, Broadband, and Planning for Public Access

    Science.gov (United States)

    Blowers, Helene

    2012-01-01

    Broadband and bandwidth allocation is an essential technology planning activity that libraries should address on a continual basis. There are five key factors that will impact your network's performance: 1. infrastructure, 2. network load, 3. workstation performance, 4. prioritization of services, and 5. network management. The author thinks it's…

  16. 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.

  17. MULTILAYER MICROSTRIP ANTENNA QUALITY FACTOR OPTIMIZATION FOR BANDWIDTH ENHANCEMENT

    OpenAIRE

    Srivastava, M. C.; SAMIR DEV GUPTA

    2012-01-01

    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....

  18. Variable bandwidth Kernel estimator of the mode

    Directory of Open Access Journals (Sweden)

    Raid B. Salha

    2009-09-01

    Full Text Available In this paper, the problem of estimating the mode of a probability density function has been studied.  Parzen (1962 proposed a kernel estimator of the mode depends on a single bandwidth. In this paper, the Parzen estimator has been improved by proposing a kernel estimator with variable bandwidth for the mode of the density function. Proceeding as in Parzen (1962, the consistency and asymptotic normality of the proposed estimator are shown. Moreover, the good  performance of the proposed estimator is tested via simulation study and it is shown that the proposed estimator is more efficient than the Parzen estimator.

  19. Effects of finite-bandwidth pump on ion heating

    International Nuclear Information System (INIS)

    The effect of finite-bandwidth pump on the ion heating is investigated experimentally. The r.f. pump frequency is broadened by amplitude modulation with a white noise source. The finite-bandwidth pump enhances the ion heating drastically compared with a monochromatic pump. There is an optimum bandwidth for the ion heating. (author)

  20. Bandwidth Efficient OFDM Transmitter Diversity Techniques

    OpenAIRE

    Lee, King F.; Williams, Douglas B.

    2004-01-01

    Space-time block-coded orthogonal frequency division multiplexing (OFDM) transmitter diversity techniques have been shown to be efficient means of achieving near-optimal diversity gain in frequency-selective fading channels. However, these known techniques all require a cyclic prefix to be added to the transmitted symbols, resulting in bandwidth expansion. In this paper, iterative space-time and space-frequency block-coded OFDM transmitter diversity techniques are proposed that exploit spati...

  1. 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).

  2. Achievement of arbitrary bandwidth of a narrow bandpass filter.

    Science.gov (United States)

    Lee, Cheng-Chung; Chen, Sheng-Hui; Kuo, Chien-Cheng; Wei, Ching-Yi

    2007-11-12

    By adjusting the coating parameters to vary the refractive index of the thin film material, we are able to fine tune the bandwidth of a narrow bandpass filter to an arbitrary value. The relation between the varied index Deltan and the maximum arbitrary bandwidth was analyzed. A 4-skip-0 bandpass filter for a 100 GHz DWDM system was designed and fabricated. In addition, the relation between the tolerance of the index and the bandwidth was also analyzed to avoid broadening or narrowing the bandwidth. The final results showed that the arbitrary bandwidth met the requirements very well. PMID:19550806

  3. Bandwidth reconfigurable microwave photonic filter based on stimulated Brillouin scattering

    Science.gov (United States)

    Xiao, Yongchuan; Wang, Xin; Zhang, Youdi; Dong, Wei; Zhang, Xindong; Liu, Caixia; Ruan, Shengping; Chen, Weiyou

    2015-01-01

    A bandwidth reconfigurable microwave photonic filter is proposed and numerically analyzed employing Brillouin gain spectrum narrowing and broadening. The stimulated Brillouin scattering (SBS) process is used to convert the phase modulation to intensity modulation to generate filter passband. Due to the fact that the passband is formed by mapping the Brillouin gain spectrum, bandwidth reconfiguration can be implemented by changing Brillouin gain linewidth. In this paper, both bandwidth reduction and increase are included in a single system and the details of gain spectrum narrowing and broadening are demonstrated. Theoretically, nearly 60% bandwidth reduction and hundreds times of bandwidth increase are achieved as compared to the case without gain spectrum process.

  4. 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.

  5. Design of a ×4 subharmonic sub-millimeter wave diode mixer, based on an analytic expression for small-signal conversion admittance parameters

    DEFF Research Database (Denmark)

    Michaelsen, Rasmus Schandorph; Johansen, Tom Keinicke

    2013-01-01

    Instead of using frequency multipliers before a fundamental mixer, subharmonic mixers can be used. In order to develop novel subharmonic mixer architectures it is necessary to know the exact signal phase at the nonlinear element. The purpose of this paper is to generalize the description of the small-signal admittance in a Schottky-diode mixer where the phase can be set arbitrarily. It is shown that only for the case of a fundamental frequency mixer this admittance becomes a purely real valued conductance. To test the theory a ×4 subharmonic sub-millimeter wave mixer is designed and simulated. With an RF frequency of 640 GHz, this design achieves a conversion gain of ?13.5 dB with a LO-power of only ?2.5 dBm.

  6. Apparent base resistance decomposition by means of small-signal and high-frequency noise analyses of submicron InP/InGaAs HBTs

    Science.gov (United States)

    Ramirez-Garcia, E.; Aniel, F. P.; Enciso-Aguilar, M. A.; Zerounian, F.

    2012-08-01

    We present an original and reliable technique to elucidate the different contributions to the apparent base resistance (RB = RBx + XRBi) of double heterojunction bipolar transistors (HBTs) designed by Alcatel-Thales III-V Lab. The extrinsic base resistance (RBx) is quantified using small-signal measurements. The base-collector junction distribution factor (X) and the intrinsic base resistance (RBi) are extracted from high-frequency noise (HFN) measurements. This method was applied to three InP/InGaAs HBTs having different emitter surfaces (SE). The correct determination of RBx, X and RBi may be a useful tool for compact and/or linear electrical modelling and may give some guidelines to designers to improve operation frequencies. Moreover, this strategy can be applied to any layout and technological variation of HBT; it can be also applied to homojunction bipolar transistors. Our results show that HFN analysis should be included to fully characterize bipolar transistors.

  7. 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 ...

  8. Bandwidth Allocation and Session Scheduling using SIP

    Directory of Open Access Journals (Sweden)

    Jean-Marie Garcia

    2006-08-01

    Full Text Available

    Session Initiation Protocol (SIP is a new signaling protocol designed to establish multimedia sessions in telecommunication networks. In this paper, we suggest the extension of SIP functionalities to coordinate QoS mechanisms deployed in IP networks, and especially in DiffServ domain. Indeed, the interaction between small and big TCP sessions may have dramatic consequences on small TCP sessions. Hence, we use SIP to achieve QoS management on a session basis, in which the over all activity of the user during the session is considered. The suggested mechanisms deal with two issues: first, session scheduling based on session duration and/or volume, and second bandwidth allocation on a per-flow basis using equivalent bandwidth estimation techniques. The proposed mechanisms are implemented in the SIP proxy server as QoS management algorithms, and they are validated by simulations.

  9. 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.

  10. Bandwidth Enhancement in Multilayer Microstrip Proximity Coupled Array

    Directory of Open Access Journals (Sweden)

    Shubham Gupta

    2012-03-01

    Full Text Available Now days, there is a huge demand for wireless applications. Antennas which are used in these applications require being low profile, light weight, easily mounted and broad bandwidth. The microstrip antenna has all the features mentioned above except for its narrow bandwidth, typically from less than 1% to several percent. This paper introduces an alternative approach in enhancing the bandwidth of the microstrip antenna. The bandwidth enhancement technique which is studied is the Proximity coupled Microstrip Antenna with Air-Gap. By using this technique, a bandwidth enhancement of 14.77% can be achieved and after that we have designed an array of proximity coupled antenna and achieved a bandwidth of 19% at afrequency of 7GHz.

  11. 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.

  12. Flexible Network Bandwidth and Latency Provisioning in the Datacenter

    OpenAIRE

    Jeyakumar, Vimalkumar; Kabbani, Abdul; Mogul, Jeffrey C.; Vahdat, Amin

    2014-01-01

    Predictably sharing the network is critical to achieving high utilization in the datacenter. Past work has focussed on providing bandwidth to endpoints, but often we want to allocate resources among multi-node services. In this paper, we present Parley, which provides service-centric minimum bandwidth guarantees, which can be composed hierarchically. Parley also supports service-centric weighted sharing of bandwidth in excess of these guarantees. Further, we show how to conf...

  13. Variable data driven bandwidth choice in nonparametric quantile regression

    OpenAIRE

    Abberger, Klaus

    2002-01-01

    The choice of a smoothing parameter or bandwidth is crucial when applying non- parametric regression estimators. In nonparametric mean regression various meth- ods for bandwidth selection exists. But in nonparametric quantile regression band- width choice is still an unsolved problem. In this paper a selection procedure for local varying bandwidths based on the asymptotic mean squared error (MSE) of the local linear quantile estimator is discussed. To estimate the unknown quantities of the MS...

  14. Bandwidth limitation of the Fabry Perot cavity antennas

    International Nuclear Information System (INIS)

    The bandwidth behavior of the Fabry Perot cavity antennas are considered on the basis of circuit theory. It is shown that the approaches of regenerative amplifier are applicable to resonator antenna. The equations for bandwidth limitation of the matched resonator antennas are obtained. It is experimentally confirmed that bandwidth of the Fabry Perot cavity antennas can be significantly enlarged by using properly selected partially reflective additional superstates

  15. A Distributed Dynamic Bandwidth Allocation Algorithm in EPON

    OpenAIRE

    Feng Cao; Deming Liu; Minming Zhang; Kang Yang; Yinbo Qian

    2010-01-01

    EPON (Ethernet Passive Optical Network) is a rising bandwidth access technology, and it could realize the comprehensive operation access including data, video, and voice, with good economic characters. IEEE 802.3ah is the industrial standard of EPON, but it doesn’t concretely regulate the uplink bandwidth allocation algorithm of EPON. Therefore, aiming at the uplink channel access of EPON, people have put forward various dynamic bandwidth allocation algorithms, but most of them belong to in...

  16. BANDWIDTH EFFICIENCY IN MAC PROTOCOL FOR AD HOC NETWORK?

    Directory of Open Access Journals (Sweden)

    Mayank Sharma

    2014-07-01

    Full Text Available Bandwidth, power and collision are considered as three important resources in wireless networks. Therefore, how to manage these resources becomes a effect on wireless ad hoc network. These effects are not present in wire line networks, and evaluation of available bandwidth in wireless networks a difficult task. Furthermore, in wireless medium the available resources also vary with the protocol and its central network i.e. ad hoc network. In this thesis, a collision-aware spectrum assignment scheme has been proposed for Bandwidth Optical Networks allocates the available bandwidth and increases energy efficiency in multi hop collection networks compared to the traditionally used random back off. We improve the MAC protocols with details about the bandwidth, power and collision used and their limitations. However, the MAC is utilizing in link layer, the channel is easy to access by the CSMA/CD scheme. All channels to establish the channels’ situation and avoid collision, in the process of the frame duration access the TDMA, i.e. time slots are required in frame duration, and FDMA (Scheduled protocol access the bandwidth allocation which every node gets a permanent allocation of bandwidth. The aim of this thesis is to initiate multiple channels in medium for FDMA, which constrain the collision of number of channel (N and utilized bandwidth (W. Therefore, how to increase a MAC protocol to improve the bandwidth efficiency and decrease the energy utilization is necessary.

  17. A study of Bandwidth Management in Computer Networks

    Directory of Open Access Journals (Sweden)

    Devajit Mahanta,

    2013-01-01

    Full Text Available Bandwidth management is one of the most widely misunderstood subjects in modern networking. Bandwidth Management is a lot like economics, because the complexities of how it works are beyond simple logic. Internet "bandwidth" is not a spectrum; traffic streams are one bit at a time. Bandwidth on the internet can only be conceptualized over time, and the amount of time that you talk about can greatly change the user experience. For reliable data transmission within computer network and internet forms the basis for management and control of bandwidth. Without bandwidth management, an user will not be able to handle all available bandwidth on the networks. It will be impossible to differentiate between various network traffics, and it will also be difficult to control which user or application has priority on the network. Applications which require specific quantity and quality of service may not be predicted in terms of available bandwidth, thus making some applications run poorly due to improper bandwidth allocation. This work focus on the development of an application to combat the challenges facing easy flow of data transmission problems in network design as organization network evolves. Here PHP Script, Apache Server and MySQL are the development tools used.

  18. Ultrabroad bandwidth for suppression of laser driven parametric instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Eimerl, D.; Kruer, W.L.; Campbell, E.M. (Lawrence Livermore National Lab., CA (United States))

    1992-08-01

    The use of laser light with a large bandwidth is a promising but relatively unexplored option for laser fusion. Large bandwidth ([Delta][omega]/[omega][sub 0]>1%) can enable efficient laser-target coupling over a significantly expanded range of laser intensity and wave-length. This would expand the options available for more optimal target design, potentially leading to higher gains with reduced laser energy. It would also provide a safety option when extrapolating to future targets. This potential impact justifies increased attention to novel ideas for achieving large bandwidth and to experiments examining laser plasma coupling with large bandwidth sources. (author).

  19. Bandwidth-tunable optical spatial filters with nanoparticle arrays.

    Science.gov (United States)

    Saeidi, Chiya; van der Weide, Daniel

    2014-05-19

    Modeling a nanoparticle array (NPA) inside a thin glass slab as a lumped optical resonator, we propose a systematic approach to design for an efficient optical filter with bandwidth tunability. The quality factor and bandwidth of the resonator are related to the physical, geometrical, and electrical parameters of an NPA and its surrounding medium, whose permittivity is varied to change the bandwidth. We propose a structure amenable to our design approach consisting of an NPA slab surrounded by liquid crystal whose permittivity can be altered. We validate the design procedure with examples of tunable-bandwidth filters at different frequency regimes from NIR to blue. PMID:24921367

  20. Optimal resource allocation in random networks with transportation bandwidths

    International Nuclear Information System (INIS)

    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

  1. 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.

  2. Ptychography with broad-bandwidth radiation

    Science.gov (United States)

    Enders, B.; Dierolf, M.; Cloetens, P.; Stockmar, M.; Pfeiffer, F.; Thibault, P.

    2014-04-01

    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.

  3. Small signal microwave amplifier design

    CERN Document Server

    Grosch, Theodore

    2000-01-01

    This book explains techniques and examples for designing stable amplifiers for high-frequency applications in which the signal is small and the amplifier circuit is linear. An in-depth discussion of linear network theory provides the foundation needed to develop actual designs. Examples throughout the book will show you how to apply the knowledge gained in each chapter leading to the complex design of low noise amplifiers. Many exercises at the end of each chapter will help students to practice their skills. The solutions to these design problems are available in an accompanying solutions book

  4. Bandwidth Reallocation Strategy for Video Communications on NGN

    Science.gov (United States)

    Song, Bin; Qin, Hao; Guo, Chunfang; Ma, Linhua

    Based on an estimation model of video subjective quality, a bandwidth reallocation strategy for video communications on NGN is presented. Experimental results show that the average PSNR of recovery video quality can be greatly increased by using the proposed method when the network bandwidth decreases.

  5. Bandwidth tunable filter based on silicon microring-MZI structure

    DEFF Research Database (Denmark)

    Ding, Yunhong; Zhang, Xinliang

    2010-01-01

    A novel bandwidth tunable bandpass filter based on a silicon microring-MZI structure is proposed and demonstrated. By thermally tuning the resonance offset between the two microring resonators, and adding the two drop transmissions together, the bandwidth of the microring-MZI filter can be easily linearly tuned with low in-band ripples.

  6. One Method of Cloud Computing Bandwidth Allocation Based on Fairness

    Directory of Open Access Journals (Sweden)

    Yiquan Kong

    2013-02-01

    Full Text Available In order to solve the bandwidth allocation unfairness problem in the cloud computing network, one method uses fairness congestion control algorithm, access control list (ACL and traffic policing and traffic shaping in the paper. The method can rationally solve the problem after analyzing the reason of cloud computing bandwidth allocation unfairness. For illustration, one network video conference example was utilized to show the method in solving bandwidth allocation unfairness problem.The experimental results show network bandwidths are fairly allocated, packet loss ratio and latency is obvious improvement. The method deals with non-adaptive UDP and TCP adaptive flow congestion and provides the end-to-end quality of service over the differentiated services networks, and the bandwidth allocation problem based on fairness in the cloud computing network is solved well.

  7. 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.

  8. Antenna of adjustable bandwidth based on a pentagonal array

    Science.gov (United States)

    Tecpoyotl-Torres, M.; Vera-Dimas, J. G.; Cabello Ruiz, R.; García-García, O.; Escobedo-Alatorre, J.; Sanchez-Mondragon, J.; Torres-Cisneros, M.; Varona, J.; Vargas-Bernal, R.

    2011-09-01

    Antenna characteristics are chosen according to the features determined by the systems where they will be used. While some systems require a very narrow bandwidth, others may operate with a much wider bandwidth. Some techniques used for increasing the bandwidth of a given antenna have considered mechanical adjustment of the air layer thickness, with the consequent change on the effective permittivity and performance. Some other systems consider a suitable choice of feeding techniques and impedance matching network. However, approaches for reducing the bandwidth have not received the same level of attention. Narrow bandwidth antennas are of particular interest in security and surveillance systems. In this work we present a technique, based on the design of a pentagonal antenna array, which allows for adjusting the bandwidth in either direction. The array is formed by an inner patch designed at the desired operating frequency of the system and a gap coupled external ring centered at a different frequency (lower or very near the operating frequency), which determines the potential bandwidth increment or decrement. The feed point is located on the inner patch. As a proof-of-concept, this work offers a tuning range that goes from -40% of the center frequency up to +50% of the center operating frequency of the patch antenna. The single patch antenna of this work was designed and simulated at an operating frequency of 4.9 GHz on RT/Duroid 5880.

  9. Bandwidth Enhancement for Microstrip Antenna in Wireless Applications

    Directory of Open Access Journals (Sweden)

    RSA Raja Abdullah

    2009-02-01

    Full Text Available Antenna is a vital component in wireless application systems. The microstrip antenna can be used for wireless applications as it has features such as light weight, easily mounted and it is easy to mass produce. Although there are many features that suits well for microstrip antenna to be deployed for wireless applications, there is a very serious limitation where it has a very narrow bandwidth. The typical bandwidth of the microstrip antennas is between 1 - 3%. If this limitation is eliminated, the microstrip antenna can be used to its full potential. An alternative bandwidth enhancement technique is studied and then proposed in order to broaden the bandwidth of the microstrip antenna. The wireless application that is selected to be studied is the Wireless Local Area Network (WLAN based on the IEEE 802.11b standard. In Malaysia, this WLAN band spans from 2.4GHz to 2.48GHz. The bandwidth enhancement technique which is selected is the Identical Dual-Patch Microstrip Antenna with Air-Gap (IDMA. By using this technique, a bandwidth enhancement of about 11% has been achieved. This bandwidth very well covers the required WLAN band with an operating frequency of 2.45GHz.

  10. Impact of Wind Power Plants with Full Converter Wind Turbines on Power System Small-Signal Stability : Inherent Characteristics and Potential for Power Oscillation Damping Control

    DEFF Research Database (Denmark)

    Knüppel, Thyge

    2012-01-01

    Wind power is being developed in power systems all around the world, and already today wind power covers more than 20 % of the electricity consumption in some countries. As the size of each wind power plant (WPP) increases and as the levels of penetration reaches certain magnitudes, the inclusion of the dynamic properties of the WPPs in the power system stability studies become important. The work presented in this report deal with the impact of WPPs based on full converter wind turbines (WTs) on the power system small-signal rotor angle stability. During small disturbances in the power system, the rotor speed of the synchronous machines will eventually return to its steady state if the power system is small-signal stable. The dynamic properties of a WPP are fundamentally dierent from those of a synchronous machine, and the interaction of WPPs with the synchronous machines in power system oscillations has not yet been fully claried. The participation of the WPP in the power system oscillations was investigated for a number of WPP penetration levels and for dierent WPP modes of operation. It was generally found that the inter-area modes were largely unaected by the WPP penetration level and mode of operation. The participation of the WT mechanical system in the inter-area modes were found to be orders of magnitudes smaller than the participation of the synchronous generators. The reactive power controller of the WPP and the WT were found have the highest participation among the WPP and WT states. WPPs based on converter interfaced WTs oer a high degree of controllability due to the rapid response of the converter and the ability to control both the active and the reactive power output. During this project, it has been explored how these properties could be utilized to actively contribute to the modal damping of weakly damped power oscillations through WPP power oscillation damping control (POD). Emphasis has been put on WPP level PODs due to its simplicity as compared to individual WT PODs, and since this oers a single point of access if the operation of the POD is to be controlled by a wide-area measurement system. The ndings encourage that a WPP level POD is feasible, since the WTs in a 150 WT WPP required very similar control signals to optimally contribute to an increased modal damping, and since time domain simulations showed that the interaction between the WTs did not adversely eect the ability of the WTs to generate an aligned WPP response. The theoretical ndings are supported with eld test results on a small 13 WT WPP that has been subject to open-loop tests of both active and reactive power modulations in the frequency range of 0:1 to 1:0 Hz. With the eld tests it has been shown that it was possible to control the WTs to deliver a common WPP response that was consistent in both frequency and phase. This was achieved for both active and reactive power modulation.

  11. Evaluation of dynamic bandwidth allocation algorithms in GPON networks

    DEFF Research Database (Denmark)

    Ozimkiewicz, J.; Ruepp, Sarah Renée

    2010-01-01

    In this paper, two approaches for Dynamic Bandwidth Allocation in GPON networks are proposed, and validated through simulations in the OPNET modeler. One approach address a Status Reporting scheme, where the bandwidth allocation originates from the client request. The second use a centralized Non Status Reporting scheme. Furthermore, parameters to cope with variances in the traffic pattern is quantified. The results on performance, scalability and efficiency show that Status Reporting is utilizing the bandwidth more efficient while the Non Status Reporting provides better QoS for real time services.

  12. A NOVEL µ-NEGATIVE METAMATERIAL WITH ENHANCED REJECTION BANDWIDTH

    Directory of Open Access Journals (Sweden)

    Haider Raad

    2013-01-01

    Full Text Available In this study, a novel planar µ-Negative (MNG metamaterial structure based on Split Ring Resonators (SRRs with improved rejection bandwidth is presented. A bridging technique is used to connect two SRR unit cells at the center to emulate a cascaded filter. The proposed structure achieved a -20 dB rejection bandwidth of 15.5% compared to 4.5% for the conventional SRRs which makes it a good candidate for integration with antennas and RF circuits that require large operational bandwidth.

  13. Large bandwidth RGC transimpedance preamplifier design in SCA

    International Nuclear Information System (INIS)

    A Large Bandwidth RGC Transimpedance Preamplifier is designed for amplifying the high-fidelity timing signal in Switch Capacitance Array chip application. This amplifier have characteristics of low input impedance, large bandwidth, high transimpedance. It will be made under TSMC 0.25?m CMOS technology, and the supply voltage is single 2.5 V. Simulation results indicate: the transimpedance is 5000 ohm, -3dB BW is 953 MHz, and the detector output capacitance have litter effect on the bandwidth in some range. (authors)

  14. Enhancement of bandwidth of planar microstrip antenna with meta materials

    OpenAIRE

    Ahmed Al-Shaheen

    2011-01-01

    In this paper we present a planar left-handed material pattern on the rectangular patch antenna mounted on the substrate is designed to enhance its horizontal radiation as well as to broaden its working bandwidth. The parametric study is done to study the effect of the ground plane slots width of 0.3, 0.4 and 0.5 mm respectively on the return loss and bandwidth enhancement, the best value of g is 0.4 mm. Enhancement in the bandwidth is achieved by introducing the meta material phenomena inste...

  15. Effects of driver bandwidth upon resonantly heated electrons

    International Nuclear Information System (INIS)

    Experimental data are presented which show that increased bandwidth of an electromagnetic driver can reduce the hot electron temperature due to resonant absorption. This work, done at microwave frequencies, shows that T/sub H/a(Dw/w)/sup -0.25/. It was also observed that the hot electron density increases with increasing bandwidth such that the heat flux (Q/sub H/an/sub H/T/sub H//sup ts3/2/) is nearly constant as a function of bandwidth

  16. 3600 digital phase detector with 100-kHz bandwidth

    International Nuclear Information System (INIS)

    The general availability of digital circuit components with propagation delay times of a few nanoseconds makes a digital phase detector with good bandwidth feasible. Such a circuit has a distinct advantage over its analog counterpart because of its linearity over wide range of phase shift. A phase detector that is being built at Los Alamos National Laboratory for the Fusion Materials Irradiation Test (FMIT) project is described. The specifications are 100-kHz bandwidth, linearity of +- 10 over +- 1800 of phase shift, and 0.660 resolution. To date, the circuit has achieved the bandwidth and resolution. The linearity is approximately +- 30 over +- 1800 phase shift

  17. Energy efficiency in elastic-bandwidth optical networks

    DEFF Research Database (Denmark)

    Vizcaino, Jorge Lopez; Ye, Yabin

    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 modulation formats offer in terms of energy efficiency.

  18. Inscription of narrow bandwidth Bragg gratings in polymer optical fibers

    International Nuclear Information System (INIS)

    We report on the inscription and characterization of narrow bandwidth fiber Bragg gratings (FBGs) in different spectral regions using polymer optical fibers (POFs). Narrow bandwidth FBGs are increasingly essential for optical filtering in POF transmission systems and photonic applications. Long FBGs with resonance wavelengths of around 600, 850 and 1550 nm were inscribed in several types of polymer optical fibers using a scanning technique with a short optical path. The technique allowed the inscription in relatively short periods of time. The achieved 3 dB bandwidth varied from 0.22 down to 0.045 nm considering FBG lengths of 10 and 25 mm, respectively. (paper)

  19. Spacer Optimization and Accurate Small-Signal Modeling of 90nm Gate Underlap SOI-MOSFETs for Low Power GHz Applications

    Directory of Open Access Journals (Sweden)

    Indra Vijay Singh

    2013-02-01

    Full Text Available This paper presents the significance of gate-source/drain extension region (also known as underlap design optimization in 90nm single gate (SG Silicon-on-Insulator (SOI MOSFET for low power GHz frequency applications. Using an optimal spacer s (? 0.8×LG, where LG is gate length, it has been found that the device exhibits intrinsic gain of ? 25 dB in low-moderate inversion region (VOD =VGS – VTH ? 90 mV, where VOD, VGS and VTH are the overdrive, gate and threshold voltages, respectively at operating frequency of 20 GHz. An accurate (including non-quasi-static and extrinsic parasitics effects small-signal model for the optimized device has been presented. The comparison of Y-parameters of 2D ATLAS with overall modeled value (up to 20 GHz has shown an excellent matching (with an average error of ?5%, whereas results from quasi-static (QS predictive technology model (PTM differ significantly (>20%. Optimized underlap device shows transit frequency fT and maximum frequency of oscillation fMAX, ~108 and ~130 GHz respectively, with noise figure (NF ~2.8 dB and exhibits unilateral power gain (ULG ~38 dB (VOD =90mV, drain-to-source current IDS ? 0.64mA and drain-to-source voltage VDS = 1V at 20 GHz. Comparison with limited measured data suggest that simulated results are in well conformity, which suggest the possibility of use of underlap device technology in the design of key blocks such as low noise amplifier LNA and mixer for GHz applications. Key Words: Gate Underlap, silicon-on-Insulator, Non-Quasi-Static, Transconductance-to-Net-Charge Ratio (TCR, Low Power.

  20. 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.

  1. Broad-bandwidth Brillouin slow light in optical fibers

    OpenAIRE

    Gonzalez Herraez, M.; Song, Kwang-yong; The?venaz, Luc

    2006-01-01

    We experimentally demonstrate that Brillouin slow light with an arbitrary large bandwidth can be readily obtained in conventional optical fibers using a simple and inexpensive pump spectral broadening technique

  2. Ultra Wideband Microstrip Diamond Slotted Patch Antenna with Enhanced Bandwidth

    Directory of Open Access Journals (Sweden)

    Chia Ping Lee

    2011-07-01

    Full Text Available An Ultra Wideband (UWB microstrip diamond slotted patch antenna with enhanced bandwidth is presented in this paper. The proposed antenna is simulated in CST Microwave Studio and fabricated for measurements. Its simulated result displays impedance bandwidth from 3.28 GHz to 19.64 GHz, whereas the measured result displays the frequency region from 2.01 GHz to 18.67 GHz. The antenna complies with the return loss of S11 < –10 dB and Voltage Standing Wave Ratio (VSWR < 2 throughout the impedance bandwidth. Details of the antenna design and related results such as phase angle, input impedance and radiation patterns are discussed in this paper. This antenna has surpassed the bandwidth of UWB requirement, which is from 3.1 GHz to 10.6 GHz, and exhibits good UWB characteristics.

  3. 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.

  4. 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.

  5. Limits To Certainty in QoS Pricing and Bandwidth

    OpenAIRE

    Gideon, Carolyn; Camp, L. Jean

    2001-01-01

    Advanced services require more reliable bandwidth than currently provided by the Internet Protocol, even with the reliability enhancements provided by TCP. More reliable bandwidth will be provided through QoS (quality of service), as currently discussed widely. Yet QoS has some implications beyond providing ubiquitous access to advance Internet service, which are of interest from a policy perspective. In particular, what are the implications for price of Internet services? F...

  6. 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...

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

    OpenAIRE

    Underwood, D. G.; Drake, 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, BE...

  8. Review of high bandwidth fiber optics radiation sensors

    International Nuclear Information System (INIS)

    This paper summarizes the use of fiber optics or guided optical systems for radiation sensors. It is limited a passive systems wherein electrical is not required at the sensor location. However, electrically powered light sources, receivers and/or recorders may still be required for detection and data storage in sensor system operation. This paper emphasizes sensor technologies that permit high bandwidth measurements of transient radiation levels, and will also discuss several low bandwidth applications. 60 refs

  9. Asymptotics and optimal bandwidth selection for highest density region estimation

    OpenAIRE

    Samworth, R. J.; Wand, M. P.

    2010-01-01

    We study kernel estimation of highest-density regions (HDR). Our main contributions are two-fold. First, we derive a uniform-in-bandwidth asymptotic approximation to a risk that is appropriate for HDR estimation. This approximation is then used to derive a bandwidth selection rule for HDR estimation possessing attractive asymptotic properties. We also present the results of numerical studies that illustrate the benefits of our theory and methodology.

  10. Available Bandwidth Estimation Strategy Based on the Network Allocation Vector

    OpenAIRE

    Hongtao Liu; Lianglun Cheng

    2012-01-01

    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 retrans...

  11. Dual-band planar quadrature hybrid with enhanced bandwidth response

    OpenAIRE

    Collado Go?mez, Juan Carlos; Grau Besoli?, Alfred; Flaviis, Franco

    2005-01-01

    This paper presents the theory, design procedure, and implementation of a dual-band planar quadrature hybrid with enhanced bandwidth. The topology of the circuit is a three-branch-line (3-BL) quadrature hybrid, which provides much larger flexibility to allocate the desired operating frequencies and necessary bandwidths than other previously published configurations. A performance comparison with other dual-band planar topologies is presented. Finally, a 3-BL quadrature hybrid for dual band (2...

  12. A Real-Time Measurement Algorithm for Available Bandwidth

    OpenAIRE

    Yin, Yi; Weidong WU

    2009-01-01

    Available bandwidth estimation is useful for route selection in overlay networks, QoS, and traffic engineer-ing. Many measurement algorithms, such as Pathload, Pathchar, and Packet Transmission Rate (PTR) method, etc. have been proposed. PTR method sends a sequence of packet trains to characterize the interac-tion between probing packets and the competing traffic, and uses the average rate of the packet train as an estimate of the available bandwidth. However, this PTR algorithm does not full...

  13. Modeling, Implementation and Evaluation of IP Network Bandwidth Measurement Methods

    OpenAIRE

    Johnsson, Andreas

    2007-01-01

    Internet has gained much popularity among the public since the mid 1990's and is now an integrated part of our society. A large range of high-speedbroadband providers and the development of new and more efficient Internet applications increase the possibilities to watch movies and live TV, use IP-telephony and share files over the Internet. Such applications demand high data transmission rates, which in turn consume network bandwidth. Since several users must share the common bandwidth capaci...

  14. Relaxor-PT single crystals for broad bandwidth, high power sonar projectors

    Science.gov (United States)

    Sherlock, Nevin P.

    2010-06-01

    The high piezoelectric response of the ferroelectric relaxor (1 - x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3 (PMNT) in single crystal form has generated significant interest in producing broad bandwidth SONAR systems. Both the piezoelectric coefficient (d33 > 2000 pC/N) and coupling coefficient (k33 > 0.90) are superior to those of conventional piezoelectric ceramics. Within the context of a high power acoustic projector, its high losses and low temperature stability have limited its development. Second generation single crystals with compositions modified from the base PMNT have been recently developed to decrease the electromechanical losses and mitigate the thermal property dependence. In this work, the electromechanical properties were measured using single crystals which have been modified in various ways. The modified crystals exhibit electromechanically "hard" behavior with lower losses (tan delta = 0.1--0.2% and QM = 230--950) than unmodified PMNT (tan delta = 0.26% and QM = 190). The measured d33 values of modified single crystals (d33 = 760--1490 pm/V) are also lower than unmodified PMNT (d33 = 1540 pm/V), but the lower piezoelectric response is compensated by the greater stability of the modified single crystals. These modified single crystal properties were also compared to conventional high power piezoelectric ceramics ( d33 = 240 pm/V and QM = 1050) to show similar losses but significantly greater response in the modified PMNT single crystals. Although most piezoelectric materials are measured under small signal conditions (small signal defined by a completely linear relationship between the input and output signals), the high power nature of SONAR projectors demands that these modified single crystals also be evaluated under high power conditions. A test procedure was developed to measure the electromechanical properties of each material as a function of applied electric field over a frequency range which includes the resonance frequency. Modified single crystals showed twice the dynamic strain of unmodified PMNT as a function of electric field, and in many cases also showed greater maximum strain at failure (0.3% compared to 0.15% for unmodified PMNT). When QM was measured as a function of drive level, it was shown to sharply decrease under high dynamic strain. Modified single crystals with greater small signal QM values than unmodified PMNT maintain higher QM values under high drive, with Q M = 50--150 immediately prior to sample failure (Q M = 20 for base PMNT immediately prior to failure). The temperature dependence of modified PMNT single crystal electromechanical properties was also determined, and it was shown that modified crystals possess greater property stability than unmodified PMNT. While the base composition shows a limiting rhombohedral-tetragonal transition at 95 °C, modified single crystals using ternary PIN and PZT components show increased transition temperatures of 125 °C and 144 °C, respectively. The greater phase stability of the PIN ternary crystal was also examined through the coercive field, which was shown to be much greater than that of unmodified PMNT over the temperature range of interest (Ec = 5 kV/cm and 2 kV/cm, respectively, at room temperature). From the combined set of property measurements, the heat generation of each material was predicted for an arbitrary projector device. As a consequence of the lower losses, modified single crystals showed as little as 25% of the heat generation value for unmodified PMNT single crystals. Using this prediction as a performance metric, the crystals with the lowest heat generation were selected for device testing. Transducers with base PMNT and modified single crystals were designed using a finite element modeling approach. This model predicted approximately two octaves of bandwidth for the transducer geometry under investigation. A 5 dB decrease in acoustic output was observed when moving from base PMNT to highly modified crystals, but that result does not account for nonlinear material behavior. Transducers fabricated using mod

  15. Statistical Multiplexing of Homogeneous Streams results in Linear Bandwidth Gains

    Directory of Open Access Journals (Sweden)

    2013-01-01

    Full Text Available Statistical multiplexing of traffic streams results in reduced network bandwidth requirement. The resulting gain increases with the increase in the number of streams being multiplexed together. However, the exact shape of the gain curve, as more and more streams are multiplexed together, is not known.

    In this paper, we first present the generalized result that the statistical gain of combining homogeneous traffic streams, of any traffic type, is a linear function of the number of streams being multiplexed. That is, given a fixed Quality of Service (QoS constraint, like percentile delay, D, the bandwidth requirement of n streams to satisfy the delay constraint D is n x R x c where R is the bandwidth requirement of a single stream that satisfies the constraint D and c e (0,1]. We present the linear bandwidth gain result, using an extensive simulation study for video traces, specifically, streaming video (IPTV traces and interactive video (CISCO Telepresence traces.

    The linear bandwidth gain result is then verified using analytical tools from two different domains. First, we validate the linearity using Queueing Theory Analysis, specifically using Interrupted Poisson Process (IPP and Markov Modulated Poisson Process (MMPP modeling. Second, we formally prove the linear behavior using the Asymptotic Analysis of Algorithms, specifically, the Big-O analysis.

  16. A Study on Impacts of RTT Inaccuracy on Dynamic Bandwidth Allocation in PON and Solution

    OpenAIRE

    Hong, Son Nguyen; Anh, Hao Nguyen; Trong, Thua Huynh

    2014-01-01

    The circle travelling delay between OLT (Optical Line Terminal) and ONU (Optical Network Unit) is one of most important items in dynamic bandwidth allocation (DBA) algorithms in PON, called RTT (Round Trip Time). The RTT is taken into account when OLT assigns the start times for upstream bandwidth grants. In most case, RTT is estimated before making bandwidth allocation decisions in dynamic bandwidth allocation algorithms. If the estimated RTT is incorrect, the bandwidth all...

  17. Bandwidth-disorder phase diagram of half doped layered manganites

    CERN Document Server

    Mathieu, R; Kaneko, Y; He, J P; Yu, X Z; Kumai, R; Arima, T; Tomioka, Y; Asamitsu, A; Matsui, Y; Tokura, Y

    2006-01-01

    Phase diagrams in the plane of $r_A$ (the average ionic radius, related to one-electron bandwidth $W$) and $\\sigma^2$ (the ionic radius variance, measuring the quenched disorder), or ``bandwidth-disorder phase diagrams'', have been established for perovskite manganites, with three-dimensional (3$D$) Mn-O network. Here we establish the intrinsic bandwidth-disorder phase diagram of half-doped layered manganites with the two-dimensional (2$D$) Mn-O network, examining in detail the ``mother state'' of the colossal magnetoresistance (CMR) phenomenon in crystals without ferromagnetic instability. The consequences of the reduced dimensionality, from 3$D$ to 2$D$, on the order-disorder phenomena in the charge-orbital sectors are also highlighted.

  18. 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.

  19. Path connectivity based spectral defragmentation in flexible bandwidth networks.

    Science.gov (United States)

    Wang, Ying; Zhang, Jie; Zhao, Yongli; Zhang, Jiawei; Zhao, Jie; Wang, Xinbo; Gu, Wanyi

    2013-01-28

    Optical networks with flexible bandwidth provisioning have become a very promising networking architecture. It enables efficient resource utilization and supports heterogeneous bandwidth demands. In this paper, two novel spectrum defragmentation approaches, i.e. Maximum Path Connectivity (MPC) algorithm and Path Connectivity Triggering (PCT) algorithm, are proposed based on the notion of Path Connectivity, which is defined to represent the maximum variation of node switching ability along the path in flexible bandwidth networks. A cost-performance-ratio based profitability model is given to denote the prons and cons of spectrum defragmentation. We compare these two proposed algorithms with non-defragmentation algorithm in terms of blocking probability. Then we analyze the differences of defragmentation profitability between MPC and PCT algorithms. PMID:23389118

  20. High bandwidth frequency lock of a rigid tunable optical cavity.

    Science.gov (United States)

    Millo, Jacques; Merzougui, Mourad; Di Pace, Sibilla; Chaibi, Walid

    2014-11-10

    In this paper, we present a high bandwidth frequency lock of a rigid tunable Fabry Perot cavity based on a set of lead zirconate titanate (PZT) actuators. The cavity spacer was specifically designed such that the frequency of the first resonance of the whole assembly under PZT excitation is above 35 kHz, thus allowing a servo-loop bandwidth of 13 kHz. It is demonstrated that no significant noise is added by the cavity to the output beam with respect to the input beam over the servo-loop bandwidth. This cavity can be used as a pre-mode cleaner in interferometric gravitational wave detectors such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo. PMID:25403002

  1. 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.

  2. Polarization-dependent bandwidth in low-index plasmonic metamaterials.

    Science.gov (United States)

    Alisafaee, Hossein; Fiddy, Michael A

    2014-12-01

    We investigate the visible range, less-than-one index bandwidth, n(?)<1, of an optical metamaterial structure composed of plasmonic gold nanoparticles, and show that it is highly dependent on the polarization of incident light. The full-wave finite element method is used to obtain the spectral characteristics of the structure. We have found spectral bands over which the structure shows the desired low index. Further, a possible increase of the bandwidth by as much as 270% is demonstrated by a change in the incident polarization that extends the low-index bandwidth range (503-600 nm) asymmetrically into a wider range (485-750 nm) covering longer wavelengths close to near infrared. This asymmetric overlap might have the potential for new optical applications. PMID:25607961

  3. Gain-switched all-fiber laser with narrow bandwidth

    DEFF Research Database (Denmark)

    Larsen, Casper; Giesberts, M.

    2013-01-01

    Gain-switching of a CW fiber laser is a simple and cost-effective approach to generate pulses using an all-fiber system. We report on the construction of a narrow bandwidth (below 0.1 nm) gain-switched fiber laser and optimize the pulse energy and pulse duration under this constraint. The extracted pulse energy is 20 ?J in a duration of 135 ns at 7 kHz. The bandwidth increases for a higher pump pulse energy and repetition rate, and this sets the limit of the output pulse energy. A single power amplifier is added to raise the peak power to the kW-level and the pulse energy to 230 ?J while keeping the bandwidth below 0.1 nm. This allows frequency doubling in a periodically poled lithium tantalate crystal with a reasonable conversion efficiency.

  4. 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...

  5. Large bandwidth, highly efficient optical gratings through high index materials

    CERN Document Server

    Rathgen, Helmut

    2008-01-01

    We analyze the diffraction characteristics of dielectric gratings that feature a high index grating layer, and devise, through rigorous numerical calculations, large bandwidth, highly efficient, high dispersion dielectric gratings in reflection, transmission, and immersed transmission geometry. A dielectric TIR grating is suggested, whose -1dB spectral bandwidth is doubled as compared to its all-glass equivalent. The short wavelength diffraction efficiency is additionally improved by allowing for slanted lamella. The grating surpasses a blazed gold grating over the full octave. An immersed transmission grating is devised, whose -1dB bandwidth is tripled as compared to its all-glass equivalent, and that surpasses an equivalent classical transmission grating over nearly the full octave. A transmission grating in the classical scattering geometry is suggested, that features a buried high index layer. This grating provides effectively 100% diffraction efficiency at its design wavelegth, and surpasses an equivalen...

  6. Bandwidth analysis of all-optical turbo-switch

    Science.gov (United States)

    Zhou, Peng; Yang, Xuelin; Hu, Xiaonan; Hu, Weisheng

    2015-01-01

    We propose and develop a frequency-domain model to analyze the bandwidth of all-optical turbo-switch. The model has taken the spatial inhomogeneity of semiconductor optical amplifier (SOA) into consideration for the first time. The simulations based on the model show that the 3-dB bandwidth of turbo-switch could reach up to ~270 GHz when the second SOA is oversaturated. However, the overshoot will be higher, which may result in the distortion of the output signal. There is a trade-off between the bandwidth and the flatness of frequency response characteristics for turbo-switch operation. In addition, the optimum position of the delay-interferometer (DI) is investigated, showing that the level of the overshoot is relatively lower if the DI is placed between the two SOAs.

  7. SATELLITE BANDWIDTH ALLOCATION FOR SATELLITE ROUTED SENSOR NETWORKS?

    Directory of Open Access Journals (Sweden)

    Ambika Telkar

    2014-06-01

    Full Text Available Next Generation Satellite Routed Sensor Systems is expected to provide disaster detection system with high real time performance. By using Satellite Networks SRSS realizes data collection from multiple sensor terminals deployed in a wide area. However an efficient access control scheme is needed to achieve multiple access from numerous sensor terminals to the satellite with its limited bandwidth. In order to efficiently resolve these problems we propose a new scheme which utilizes a divide and conquer approach for efficient bandwidth allocation. Numerical results demonstrate the effectiveness of proposal.

  8. Effective Bandwidth Utilization in IEEE802.11 for VOIP

    OpenAIRE

    Vijay Bhanu, S.; Rm, Chandrasekaran; 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...

  9. Uniform asymptotics for kernel density estimators with variable bandwidths

    CERN Document Server

    Giné, Evarist

    2010-01-01

    It is shown that the Hall, Hu and Marron [Hall, P., Hu, T., and Marron J.S. (1995), Improved Variable Window Kernel Estimates of Probability Densities, {\\it Annals of Statistics}, 23, 1--10] modification of Abramson's [Abramson, I. (1982), On Bandwidth Variation in Kernel Estimates - A Square-root Law, {\\it Annals of Statistics}, 10, 1217--1223] variable bandwidth kernel density estimator satisfies the optimal asymptotic properties for estimating densities with four uniformly continuous derivatives, uniformly on bounded sets where the preliminary estimator of the density is bounded away from zero.

  10. Ultra Wideband Microstrip Diamond Slotted Patch Antenna with Enhanced Bandwidth

    OpenAIRE

    Chia Ping Lee; Chandan Kumar Chakrabarty

    2011-01-01

    An Ultra Wideband (UWB) microstrip diamond slotted patch antenna with enhanced bandwidth is presented in this paper. The proposed antenna is simulated in CST Microwave Studio and fabricated for measurements. Its simulated result displays impedance bandwidth from 3.28 GHz to 19.64 GHz, whereas the measured result displays the frequency region from 2.01 GHz to 18.67 GHz. The antenna complies with the return loss of S11 < –10 dB and Voltage Standing Wave Ratio (VSWR) < 2 throughout the i...

  11. Bandwidth Enhancement of Probe Fed Microstrip Patch Antenna

    Directory of Open Access Journals (Sweden)

    Parminder Singh

    2013-01-01

    Full Text Available Microstrip patch antenna becomes verypopular day by day because of its ease of analysis andfabrication, low cost, light weight, easy to feed and theirattractive radiation characteristics. Although patchantenna has numerous advantages, it has also somedrawbacks such as restricted bandwidth, and a potentialdecrease in radiation pattern. Different techniques forbandwidth enhancement of conventional rectangularmicrostrip antenna are proposed in this paper. Byincreasing the height of patch , increasing the substratethickness and decreasing the permittivity of substrate the%bandwidth is increased. HFSS Software is used for thesimulation and design calculation of microstrip patchantenna. The return loss, vswr curve, directivity and gainare evaluated.

  12. Ultrafast pulsed laser utilizing broad bandwidth laser glass

    Science.gov (United States)

    Payne, Stephen A. (Castro Valley, CA); Hayden, Joseph S. (Clarks Summit, PA)

    1997-01-01

    An ultrafast laser uses a Nd-doped phosphate laser glass characterized by a particularly broad emission bandwidth to generate the shortest possible output pulses. The laser glass is composed primarily of P.sub.2 O.sub.5, Al.sub.2 O.sub.3 and MgO, and possesses physical and thermal properties that are compatible with standard melting and manufacturing methods. The broad bandwidth laser glass can be used in modelocked oscillators as well as in amplifier modules.

  13. Small Bandwidth Asymptotics for Density-Weighted Average Derivatives

    DEFF Research Database (Denmark)

    Cattaneo, Matias D.; Crump, Richard K.

    2008-01-01

    This paper proposes (apparently) novel standard error formulas for the density-weighted average derivative estimator of Powell, Stock, and Stoker (1989). Asymptotic validity of the standard errors developed in this paper does not require the use of higher-order kernels and the standard errors are "robust" in the sense that they accommodate (but do not require) bandwidths that are smaller than those for which conventional standard errors are valid. Moreover, the results of a Monte Carlo experiment suggest that the finite sample coverage rates of con…dence intervals constructed using the standard errors developed in this paper coincide (approximately) with the nominal coverage rates across a nontrivial range of bandwidths.

  14. Bandwidth effects in Brillouin scattering from inhomogeneous plasma

    International Nuclear Information System (INIS)

    Convective Brillouin amplification in inhomogeneous, drifting plasmas is discussed. The bandwidth of the amplifier is a function of both wave damping and plasma inhomogeneity. For any given plasma model and source spectrum, the final amplified spectrum can be constructed, including the effects of inhomogeneity, drift, damping, and gain narrowing. Conversely, the shape of observed spectra of Brillouin scattering can be used to obtain information about conditions in the underdense plasma corona if it can be assumed that amplification is high enough that the final spectral bandwidth is amplifier dominated

  15. Enhancement bandwidth of microstrip antenna using tapered single slot

    OpenAIRE

    Dheyab Al-sajee, Ali A.

    2012-01-01

    A modified rectangular patch antenna design has been proposed in this paper, the bandwidth of this antenna is enhancement using the tapered slot with type of feeding (probe feed). This design is simulated with microwave office 2008 software package. This method is employed for analysis at the frequency band of (1 GHz- -- 3 GHz). When it was changed the location and dimensions of tapered slot. It gives a good VSWR less than (2), return losses (RL) less than (- 10 dB) and impedance bandwidth of...

  16. Enhancement bandwidth of microstrip antenna using tapered single slot

    Directory of Open Access Journals (Sweden)

    Ali A. Dheyab Al-Sajee

    2012-01-01

    Full Text Available A modified rectangular patch antenna design has been proposed in this paper, the bandwidth of this antenna is enhancement using the tapered slot with type of feeding (probe feed. This design is simulated with microwave office 2008 software package. This method is employed for analysis at the frequency band of (1 GHz- -- 3 GHz. When it was changed the location and dimensions of tapered slot. It gives a good VSWR less than (2, return losses (RL less than (- 10 dB and impedance bandwidth of the order of (13.1% at the frequency band of (2.2921GHz- 2.6063 GHz of [2-3] GHz.

  17. Fabrication of high frequency ultrasonic probe with wide bandwidth

    International Nuclear Information System (INIS)

    This paper is about fabrication of a wide band 2 MHz ultrasonic probe for NDT application. The piezoelectric material used is PZT. To achieve wide band operation, a backing layer is attached to the rear face and a matching/ protective layer is attached to the rear face. Backing layer is a mixture of epoxy and tungsten powder while matching layer is white alumina. The fabricated probe shows bandwidth of 53 % with centre frequency of 2.13 MHz. The pulse width at 50 % amplitude is 2.47 ?s. A wide bandwidth probe was successfully fabricated. (author)

  18. Extending the Bandwidth of Electric Ring Resonator Metamaterial Absorber

    International Nuclear Information System (INIS)

    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. (fundamental areas of phenomenology(including applications))

  19. Improving Bandwidth Efficiency in E-band Communication Systems

    OpenAIRE

    Mehrpouyan, Hani; Khanzadi, M. Reza; Matthaiou, Michail; Sayeed, Akbar M.; Schober, Robert; Hua, Yingbo

    2013-01-01

    The allocation of a large amount of bandwidth by regulating bodies in the 70/80 GHz band, i.e., the E-band, has opened up new potentials and challenges for providing affordable and reliable Gigabit per second wireless point-to-point links. This article first reviews the available bandwidth and licensing regulations in the E-band. Subsequently, different propagation models, e.g., the ITU-R and Cane models, are compared against measurement results and it is concluded that to m...

  20. A Simple Mechanism for Throttling High-Bandwidth Flows

    Directory of Open Access Journals (Sweden)

    Bill Lin

    2008-10-01

    Full Text Available This letter presents BREATHe, a simple packet dropping scheme for identifying and throttling unresponsive or misbehaving high-bandwidth flows during times of congestion. BREATHe is different from the existing active queue management techniques in that it uses heavy-hitter set analysis to identify highbandwidth flows rather than sampling or rate estimation. Specifically, BREATHe uses heavy-hitter set analysis to detect highbandwidth flows that exceed some target rate rlimit and preferentially drop packets from these flows. We show that the proposed mechanism is effective at throttling high-bandwidth flows using a small amount of state and low-complexity operation.

  1. Bandwidth based electrical-analogue battery modeling for battery modules

    Science.gov (United States)

    Li, Jianwei; Mazzola, Michael S.; Gafford, James; Jia, Bin; Xin, Ming

    2012-11-01

    A technique for building a high fidelity electrical-analogue battery model by identifying the model parameters at the module level, as opposed to the cell level, is proposed in this paper. The battery model, which is represented by electrical circuit components, can be easily integrated into popular simulation environments for system level design and predictive analysis. A novel bandwidth based time-domain procedure is introduced for identifying the model parameters by selective assignment of the limited bandwidth of the battery model approximation according to the natural bandwidth of the system that uses the battery. The aim of this paper is to provide an accurate off-line electrical-analogue battery model for simulation of larger systems containing large-format batteries, as opposed to a detailed electrochemical model suitable for simulation of internal battery processes. The proposed procedure has been experimentally verified on a 6.8 Ah Ultralife UBBL10 Li-ion battery module which is a “microcosm” for a modern large-format battery pack. A maximum 0.25% error was observed during a performance test with arbitrary but bandwidth-limited charging and discharging intervals characteristic of a typical battery application.

  2. 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.

  3. The Learning Computer: Low Bandwidth Tool that Bridges Digital Divide

    Science.gov (United States)

    Johnson, Russell; Kemp, Elizabeth; Kemp, Ray; Blakey, Peter

    2007-01-01

    This article reports on a project that explores strategies for narrowing the digital divide by providing a practicable e-learning option for the millions living outside the ambit of high performance computing and communication technology. The concept is introduced of a "learning computer," a low bandwidth tool that provides a simplified,…

  4. A Practical Approach For Excess Bandwidth Distribution for EPONs

    KAUST Repository

    Elrasad, Amr

    2014-03-09

    This paper introduces a novel approach called Delayed Excess Scheduling (DES), which practically reuse the excess bandwidth in EPONs system. DES is suitable for the industrial deployment as it requires no timing constraint and achieves better performance compared to the previously reported schemes.

  5. When Are Online and Offline Excess Bandwidth Distribution Useful in EPONs?

    Science.gov (United States)

    Ferguson, Jason R.; McGarry, Michael P.; Reisslein, Martin

    Excess bandwidth distribution techniques have recently been proposed to improve the dynamic bandwidth allocation in EPONs. We compare existing offline excess bandwidth distribution with conventional IPACT Limited in terms of packet delay performance. We identify the factors that result in packet delay reduction with excess bandwidth distribution compared to IPACT-Limited and discover that existing offline excess distribution mechanisms become unstable at moderate to high loads in long-range EPONs with large round trip propagation delays. We propose and evaluate a novel Online Excess Bandwidth Distribution (OEBD) mechanism to provide stable excess bandwidth distribution even at high loads in long-range EPONs.

  6. Bandwidth-Unlimited, Dispersion-Free Tunable Optical Delay Using a Prism Pair

    CERN Document Server

    Kim, C

    2009-01-01

    We report a nearly perfect bandwidth-unlimited, dispersion-free tunable optical delay system using a prism pair. The observed delay-bandwidth product using a 25-femtosecond light pulse is ~7x104, where the delay time is independent of the signal bandwidth. The present technique breaks from the conventional methods constrained by delay-bandwidth product, nontunability, and delay time dependent optical loss.

  7. 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.

  8. Increasing the effective bandwidth of a laser-fusion driver

    International Nuclear Information System (INIS)

    The absorption of narrow-band 1.06 ?m radiation by laser-fusion targets has been less than predicted by classical physics. Thus, early extrapolations of neutron yields and fuel densities that would be achieved as more powerful lasers come on-line have not been fully realized. However, recent experiments at KMS and GILM Ecole Polytechnique are encouraging in that they have shown agreement with theoretical predictions that laser/target interactions should improve at shorter laser wavelengths. More recently theoretical treatments have further suggested that energy absorption may improve if the laser bandwidth can be increased to several percent of the laser frequency. Preliminary experiments at KMS using a plasma filter to broaden the bandwidth tend to support these predictions, but the results are not yet conclusive

  9. Two genetic algorithms for the bandwidth multicoloring problem

    Directory of Open Access Journals (Sweden)

    Fijuljanin Jasmina

    2012-01-01

    Full Text Available In this paper the Bandwidth Multicoloring Problem (BMCP and the Bandwidth Coloring Problem (BCP are considered. The problems are solved by two genetic algorithms (GAs which use the integer encoding and standard genetic operators adapted to the problems. In both proposed implementations, all individuals are feasible by default, so search is directed into the promising regions. The first proposed method named GA1 is a constructive metaheuristic that construct solution, while the second named GA2 is an improving metaheuristic used to improve an existing solution. Genetic algorithms are tested on the publicly-available GEOM instances from the literature. Proposed GA1 has achieved a much better solution than the calculated upper bound for a given problem, and GA2 has significantly improved the solutions obtained by GA1. The obtained results are also compared with the results of the existing methods for solving BCP and BMCP.

  10. On Free-Electron Laser Growing Modes and their Bandwidth

    CERN Document Server

    Webb, Stephen; Litvinenko, Vladimir

    2011-01-01

    Free-electron lasers play an increasing role in science, from generating unique femtosecond X- ray pulses for single short recording of the protein structures to amplifying feeble interactions in advanced cooling systems for high-energy hadron colliders. While modern Free-electron laser codes can describe their amplification mechanism, a deep analytical understanding of the mechanism is of extreme importance for a number of applications. Mode competition, their growth rates and amplification bandwidth are among the most important parameters of a free-electron laser. A dispersion relation, which defines these important characteristics, can be solved analytically only for a very few simple cases. In this letter we show that for a typical bell-shape energy distribution in electron beam there is no more that one growing mode. We also derive an analytical expression which determines the bandwidth of the free-electron laser.

  11. The Bandwidths of a Matrix. A Survey of Algorithms

    Directory of Open Access Journals (Sweden)

    Mafteiu-Scai Liviu Octavian

    2014-12-01

    Full Text Available The bandwidth, average bandwidth, envelope, profile and antibandwidth of the matrices have been the subjects of study for at least 45 years. These problems have generated considerable interest over the years because of them practical relevance in areas like: solving the system of equations, finite element methods, circuit design, hypertext layout, chemical kinetics, numerical geophysics etc. In this paper a brief description of these problems are made in terms of their definitions, followed by a comparative study of them, using both approaches: matrix geometry and graph theory. Time evolution of the corresponding algorithms as well as a short description of them are made. The work also contains concrete real applications for which a large part of presented algorithms were developed.

  12. A wide-bandwidth and high-sensitivity robust microgyroscope

    International Nuclear Information System (INIS)

    This paper reports a microgyroscope design concept with the help of a 2 degrees of freedom (DoF) sense mode to achieve a wide bandwidth without sacrificing mechanical and electronic sensitivity and to obtain robust operation against variations under ambient conditions. The design concept is demonstrated with a tuning fork microgyroscope fabricated with an in-house silicon-on-glass micromachining process. When the fabricated gyroscope is operated with a relatively wide bandwidth of 1 kHz, measurements show a relatively high raw mechanical sensitivity of 131 µV (° s?1)?1. The variation in the amplified mechanical sensitivity (scale factor) of the gyroscope is measured to be less than 0.38% for large ambient pressure variations such as from 40 to 500 mTorr. The bias instability and angle random walk of the gyroscope are measured to be 131° h?1 and 1.15° h?1/2, respectively

  13. Optical lightpipe as a high-bandwidth fusion diagnostic

    Science.gov (United States)

    Moran, M. J.; Lerche, R. A.; Mant, G.; Glebov, V. Yu.; Sangster, T. C.; Mack, J. M.

    2006-10-01

    A recent series of experiments at the University of Rochester Laboratory for Laser Energetics OMEGA facility studied the feasibility of using radiation-to-light converters and high-bandwidth optical signal transmission to remote recording devices as an alternate nuclear diagnostic method. A prototype system included a radiation-to-light converter, a multiple-section lightpipe consisting of stainless steel tubes with polished interiors and turning mirrors, and a streak camera or photomultiplier/digitizer combination for signal recording. Several different radiation-to-light converters (scintillators, glasses, plastics, and pressurized CO2) performed well and produced predictable optical emissions. The lightpipe transmitted high-bandwidth optical signals to the recording stations. Data were recorded with the streak camera, the photomultiplier/digitizer, and with both recorders simultaneously.

  14. Wide-bandwidth time decay signatures from UXO targets

    Science.gov (United States)

    Nelson, Carl V.; Keller, Mary

    2002-08-01

    This paper presents wide bandwidth, time decay signatures from recent unexploded ordnance (UXO) field experiment at a US Government UXO test site. While current technologies have shown the ability to detect buried metal objects, they tend to fail in discriminating the UXOs from metal objects that pose no risk. Metal target time decay measurements have been shown to be an excellent method for target classification and identification. The present paper addresses the research community's need for accurate, wide-bandwidth UXO target signatures. Metal target signatures for a number of important UXO targets are presented in the paper for both vertical and horizontal magnetic field excitation. Target time decay signatures from about 30 microseconds to 8 milliseconds are presented. Target signatures are also characterized using a non-linear parameterization scheme in an effort to develop a compact target signature library.

  15. Bandwidth analysis of functional interconnects used as test access mechanism

    OpenAIRE

    Berg, A. van den; Ren, P.; Marinissen, EJ (Erik Jan); Gaydadjiev, GN; Goossens, KGW (Kees)

    2010-01-01

    Test data travels through a System on Chip (SOC) from the chip pins to the Core-Under-Test (CUT) and vice versa via a Test Access Mechanism (TAM). Conventionally, a TAM is implemented using dedicated communication infrastructure. However, also existing functional interconnect, such as a bus or Network on Chip (NOC), can be reused as TAM; this will reduce the overall design effort and associated silicon area. For a given core, its test set, and maximal bandwidth that the functional interconnec...

  16. Latency and Bandwidth Analysis of LTE for a Smart Grid

    OpenAIRE

    Xu, Yuzhe

    2011-01-01

    Smart grid has been proposed as an alternative to the traditional electricity grid recently thanks to its advantages of real time control on consumption demands. The latest wireless network, 3GPP Long Term Evolution (LTE), is considered to be a promising solution to interconnecting the smart objects in a smart grid because LTE provides both low latency and large bandwidth. However, the theories and standards for deploying a smart grid are still under study. Furthermore, the performance of LTE...

  17. Bandwidth and Energy Efficient Decentralized Sequential Change Detection

    OpenAIRE

    Fellouris, Georgios; Moustakides, George V.

    2012-01-01

    The problem of decentralized sequential change detection is considered, where an abrupt change occurs in an area monitored by a number of sensors; the sensors transmit their data to a fusion center, subject to bandwidth and energy constraints, and the fusion center is responsible for detecting the change as soon as possible. A novel sequential detection rule is proposed that requires communication from the sensors at random times and transmission of only low-bit messages, on...

  18. Introducing a Performance Model for Bandwidth-Limited Loop Kernels

    OpenAIRE

    Treibig, Jan; Hager, Georg

    2009-01-01

    We present a performance model for bandwidth limited loop kernels which is founded on the analysis of modern cache based microarchitectures. This model allows an accurate performance prediction and evaluation for existing instruction codes. It provides an in-depth understanding of how performance for different memory hierarchy levels is made up. The performance of raw memory load, store and copy operations and a stream vector triad are analyzed and benchmarked on three moder...

  19. High bandwidth tunability in a smart vibration absorber

    Science.gov (United States)

    Flatau, Alison B.; Dapino, Marcelo J.; Calkins, Frederick T.

    1998-06-01

    The theory of an electrically tunable Terfenol-D vibration absorber is developed in this paper. An overview of mangetostriction including discussion of the (Delta) E effect is presented. Experimental results showing agreement with prior art are included that demonstrate electrical control of a magnetostrictive actuator resonant frequency by varying the resonance between 1275 Hz and 1725 Hz. The tunability of the transducer resonant frequency is then implemented to achieve high bandwidth tunability in the performance of a Terfenol-D vibration absorber.

  20. A comparison of bandwidth selectors for mean shift clustering

    OpenAIRE

    Chaco?n, Jose? E.; Monfort, Pablo

    2013-01-01

    We explore the performance of several automatic bandwidth selectors, originally designed for density gradient estimation, as data-based procedures for nonparametric, modal clustering. The key tool to obtain a clustering from density gradient estimators is the mean shift algorithm, which allows to obtain a partition not only of the data sample, but also of the whole space. The results of our simulation study suggest that most of the methods considered here, like cross validat...

  1. A Construction of Systematic MDS Codes with Minimum Repair Bandwidth

    CERN Document Server

    Wu, Yunnan

    2009-01-01

    In a distributed storage system based on erasure coding, an important problem is the \\emph{repair problem}: If a node storing a coded piece fails, in order to maintain the same level of reliability, we need to create a new encoded piece and store it at a new node. This paper presents a construction of systematic $(n,k)$-MDS codes for $2k\\le n$ that achieves the minimum repair bandwidth when repairing from $k+1$ nodes.

  2. Cryptanalysis of an Image Scrambling Scheme without Bandwidth Expansion

    OpenAIRE

    Li, SJ; Li, CQ; Lo, KT; Chen, GR

    2008-01-01

    Recently, a new image scrambling (i.e., encryption) scheme without bandwidth expansion was proposed based on two-dimensional discrete prolate spheroidal sequences. A comprehensive cryptanalysis is given here on this image scrambling scheme, showing that it is not sufficiently secure against various cryptographical attacks including ciphertext-only attack, known/chosen-plaintext attack, and chosen-ciphertext attack. Detailed cryptanalytic results suggest that the image scrambling scheme can on...

  3. High bandwidth second-harmonic generation in partially deuterated KDP

    International Nuclear Information System (INIS)

    We have experimentally determined the spectrally noncritical phasematching behavior of Type I frequency doubling in KDP and its dependence on deuteration level in partially deuterated KDP. The first order wavelength sensitivity parameter??k/?? for Type I doubling of 1.053 ?m light vanishes for a KD*P crystal with a deuteration level between 10 and 14%. Very high bandwidth frequency doubling of Nd:glass lasers is possible with such a crystal

  4. Alternative Schemes for High-Bandwidth Instruction Fetching

    OpenAIRE

    Michaud, Pierre; Seznec, André; Jourdan, Stéphan; Sainrat, Pascal

    1998-01-01

    Future processors combining out-of-order execution with aggressive speculation techniques will need to fetch multiple non-consecutive instruction blocks in a single cycle to achieve high-performance. Several high-bandwidth instruction fetching schemes have been proposed in the past few years. The Two-Block Ahead (TBA) branch predictor predicts two non-consecutive instruction blocks per cycle while relying on a conventional instruction cache. The trace cache (TC) records traces of instructions...

  5. Instantaneous frequency, instantaneous bandwidth and the analysis of multicomponent signals

    OpenAIRE

    G. Jones; Boashash, B.

    1990-01-01

    The definitions of instantaneous frequency are reviewed in the context of signal theory, communication theory and discrete time implementations. The spread of a signal about its instantaneous frequency, or instantaneous bandwidth, is investigated for several common time-frequency distributions by simulations. The instantaneous frequency of a multicomponent signal is examined. Further investigation of the time-frequency representation of a multicomponent signal leads to an adaptive algorithm w...

  6. Ranging with ultrawide bandwidth signals in multipath environments

    OpenAIRE

    Dardari, Davide; Ferner, Ulric John; Conti, Andrea; Giorgetti, Andrea; Win, Moe Z.

    2008-01-01

    Over the coming decades, high-definition situationally-aware networks have the potential to create revolutionary applications in the social, scientific, commercial, and military sectors. Ultrawide bandwidth (UWB) technology is a viable candidate for enabling accurate localization capabilities through time-of-arrival (TOA)-based ranging techniques. These techniques exploit the fine delay resolution property of UWB signals by estimating the TOA of the first signal path. Exploiting the full capa...

  7. A hybrid ACO approach to the Matrix Bandwidth Minimization Problem

    OpenAIRE

    Pintea, Camelia-M.; Chira, Camelia; Crisan, Gloria-C.

    2012-01-01

    The evolution of the human society raises more and more difficult endeavors. For some of the real-life problems, the computing time-restriction enhances their complexity. The Matrix Bandwidth Minimization Problem (MBMP) seeks for a simultaneous permutation of the rows and the columns of a square matrix in order to keep its nonzero entries close to the main diagonal. The MBMP is a highly investigated P-complete problem, as it has broad applications in industry, logistics, art...

  8. DBA-VM: Dynamic bandwidth allocator for virtual machines

    OpenAIRE

    Amamou, Ahmed; Bourguiba, Manel; Haddadou, Kamel; Pujolle, Guy

    2012-01-01

    Cloud computing is an emergent paradigm that allows customers to rent infrastructure, platforms and software as a service. With resource sharing and reuse through virtualization technology, cloud environments become even more cost effective and flexible. Nevertheless, networking within virtualized cloud still presents some challenges in performance and resource allocation. In this paper, we propose DBA-VM, a Dynamic Bandwidth Allocator for Virtual Machines with regard to the established SLAs....

  9. Terahertz bandwidth integrated radio frequency spectrum analyzer via nonlinear optics

    OpenAIRE

    Ferrera, Marcello; Reimer, Christian; Pasquazi, Alessia; Peccianti, Marco; Clerici, Matteo; Caspani, Lucia; Chu, Sai T.; Little, Brent E.; Morandotti, Roberto; Moss, David J.

    2014-01-01

    We report an integrated all-optical radio frequency spectrum analyzer based on a ~ 4cm long doped silica glass waveguide, with a bandwidth greater than 2.5 THz. We use this device to characterize the intensity power spectrum of ultrahigh repetition rate mode-locked lasers at repetition rates up to 400 GHz, and observe dynamic noise related behavior not observable with other techniques.

  10. Enhanced Gain and Bandwidth of Patch Antenna Using EBG Substrates

    OpenAIRE

    Mst. Nargis Aktar; Muhammad Shahin Uddin; Ruhul Amin; Mortuza Ali

    2011-01-01

    Microstrip patch antenna becomes very popular day by day because of its ease of analysis andfabrication, low cost, light weight, easy to feed and their attractive radiation characteristics. Althoughpatch antenna has numerous advantages, it has also some drawbacks such as restricted bandwidth, lowgain and a potential decrease in radiation pattern. In recent years, attention to use Electromagnetic BandGap (EBG) substrates to overcome the limitations of patch antenna. In this paper, we propose a...

  11. Estimates of intensity, wavelength, and bandwidth scaling of Brillouin backscatter

    International Nuclear Information System (INIS)

    A simple nonlinear, one-dimensional spherical Brillouin model adapted from kinetic simulations and Kruer's theory to a fluid code (LASNEX) is described. Laser absorption and Brillouin reflection are plotted for 0.26501316 W/cm2 on gold disks (pulse length of 1 nsec) and the calculated absorption compared to experiments. Kinetic simulations suggest methods of reducing Brillouin reflection, such as a wide bandwidth and multiline laser

  12. Large-bandwidth data acquisition network for XFEL facility, SACLA

    International Nuclear Information System (INIS)

    The SACLA (SPring-8 Angstrom Compact Free Electron Laser) facility consists of an accelerator building, an undulator building and an experimental facility. SACLA is designed to produce X-ray with a wavelength as short as 0.06 nm and with a repetition rate of 60 Hz. X-ray Free-Electron Laser (XFEL) experiments demands large bandwidth network for data acquisition (DAQ). At SACLA the experimental data rate is to be up to 5.8 Giga bit per second (Gbps). Some of the experiments demands preprocessing and on-line analysis by high-performance computers. In order to fulfill these requirements, a dedicated network system for DAQ and data analysis has been developed. A DAQ network consists of a dedicated 10 Gbps Ethernet (10 GbE) physical layer to secure the data bandwidth and a 1 GbE layer for instrument controls. The DAQ network is connected to a primary storage and indirectly to a PC cluster for data preprocessing. A fire-wall system with virtual private network (VPN) features is also implemented in order to secure remote access from off-site institutes. The use of a large-bandwidth data transfer technique allows the efficient transfer of pre-processed data from SACLA to an off-site supercomputer

  13. 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.

  14. Analysis of Bandwidth Recycling in IEEE 802.16 Network Using PSA, RB-RFA & HSA

    Directory of Open Access Journals (Sweden)

    Nilesh M. Verulkar

    2014-06-01

    Full Text Available IEEE 802.16 network protocol is designed to provide a Worldwide Interoperability for Microwave Access (WiMAX. Due to limited bandwidth and an expensive radio spectrum available for communication, it is necessary to use one bandwidth more than one time in a same network when it became unused. For that purpose “Bandwidth Recycling” concept is introduced. The spectrum (bandwidth is specifically allocated by agency to various users, but many times it is seen that the spectrum is not fully utilized by the users in the specific interval. This unused bandwidth can be allocated to other users who demands for more bandwidth for that specific interval without changing existing bandwidth scheme. In this paper we analyse different algorithms which does the recycling of bandwidth as per need is presented. To recycle the unused bandwidth priority based scheduling (PSA algorithm has been developed & to improve the recycling effectiveness rejected bandwidth request first algorithm (RBRFA and history based scheduling algorithm (HSA are outlined. By implementing these all algorithm in Netbean (Version 7.4 Simulator, we have evaluated the performance of our system. Our simulation and analysis result confirmed that the proposed system can recycle unused bandwidth.

  15. Bandwidth limitations in current mode and voltage mode integrated feedback amplifiers

    DEFF Research Database (Denmark)

    Bruun, Erik

    1995-01-01

    The bandwidth relations of feedback amplifiers have been the subject of intense interest in recent years. Many current mode devices such as current feedback amplifiers have appeared which seem to break what has been considered almost a fundamental law that the product of closed loop gain and closed loop bandwidth remains constant for a feedback amplifier. The constant-bandwidth relations of such amplifier designs are reviewed in this paper and they are combined with the constraints imposed by technology when the feedback amplifier is to be designed in an integrated technology. From this analysis it is concluded that although very high performance designs are indeed feasible with the constant-bandwidth configurations, there are no constant-bandwidth configurations which provide a higher potential loop gain and closed loop bandwidth than the constant gain-bandwidth product configurations

  16. Study and Analysis of Bandwidth Flow Estimation Techniques for Wired/Wireless Networks

    Directory of Open Access Journals (Sweden)

    Pallavi Sharma

    2012-01-01

    Full Text Available In this topic, an analysis will be made on bandwidth flow estimation technique which comes under networking domain. Correct bandwidth constrained applications and tools are required for proper bandwidth estimation. A proper monitoring of available bandwidth is required during execution to avoid degradation in performance. A several measurement tools have been proposed in the last few years. After the implementation of 802.11e Wireless Sensor Networks are capable to provide good level of QoS but research works are not much for improving performance of bandwidth constraint applications by checking sufficiency of bandwidth available in transmission route. In this topic we will do the analysis of bandwidth flow estimation technique for wired/wireless networks and we will do comparisons of existing estimation tools.

  17. Request-based Dynamic Bandwidth Allocation of Gigabit Passive Optical Network

    Directory of Open Access Journals (Sweden)

    Chih-Ta Chiu

    2013-06-01

    Full Text Available We propose request-based dynamic bandwidth allocation (DBA of gigabit passive optical network (GPON. The optical line terminal (OLT in GPON grants bandwidth to optical network units (ONUs. ONUs report request bandwidth which depends on queue lengths of traffic containers (TCONTs to the OLT. In the OLT, DBA of GPON supports a request-based polling order to allocate bandwidth. Our request-based dynamic bandwidth allocation focuses on weight assignments in the request-based polling order. Weight assignments allocate bandwidth in proportion to guaranteed and request bandwidth. We use the C program to simulate results. Simulated results indicate improved performance in queueing delay when total offered loads are or are not shared uniformly to TCONTs.

  18. Dynamic Bandwidth Allocation Performance for Dual QoS Classes in Resilient Packet Ring

    Science.gov (United States)

    Okumura, Yasuyuki

    This paper proposes an improved dynamic bandwidth allocation algorithm for dual Quality of Service (QoS) classes to maximize the utilization rate of the Resilient Packet Ring (RPR). To achieve dynamic bandwidth allocation for the two QoS classes in the RPR, each node measures the high priority traffic flow and assigns the appropriate bandwidth; the remaining bandwidth is used for low priority traffic. It passes a control frame containing the measured bandwidth of the high priority traffic to the other nodes. Based on the advertised high priority traffic bandwidth, any node that is congested transmits, to the other nodes, a fairness message to fairly allocate the remaining low priority bandwidth. Simulations demonstrate that the proposed algorithm enhances the utilization rate and reduces the delay of high priority frames.

  19. Bandwidth optimization of individual hop for robust data streaming on emergency medical application

    Directory of Open Access Journals (Sweden)

    A. K. M. Fazlul Haque

    2009-10-01

    Full Text Available This paper presents a new bandwidth estimation method for individual hop for high-speed, non-invasive, and faster convergence transmission in multiple medical data networks. Available Bandwidth Estimation Technique for individual Hops (ABETH has been developed employing parameters like Hop (H, Capacity (C, Bandwidth (B, Available Bandwidth (AB etc. Bandwidth estimation techniques, tools and methods are considered to develop the technique and it represents an effective combination of different other existing techniques aiming to exploit the positive aspects of them. More precisely, the technique which is implied in the method modifies and integrates the one recent tool SPRUCE which estimates available bandwidth and the IP layer capacity estimation formula which measures capacity. This technique provides a linear combination of capacity versus bandwidth which satisfies the link utilization demand.

  20. Wide-bandwidth piezoelectric energy harvester with polymeric structure

    Science.gov (United States)

    Rezaeisaray, Mehdi; El Gowini, Mohamed; Sameoto, Dan; Raboud, Don; Moussa, Walied

    2015-01-01

    A polymer based energy harvester with wide bandwidth is designed, fabricated and tested in this work. A polymer based structure has a lower resonance frequency compared to a silicon based structure with the same dimensions due to the much lower stiffness of polymeric materials. Therefore, a polymeric energy harvester is more useful for situations with lower ambient vibration frequencies. Aluminum nitride pads are fabricated on an SU-8 membrane to convert mechanical vibration of the membrane to electrical voltage. A new and scalable microfabrication process flow is proposed to properly fabricate piezoelectric layers on SU-8 structures. The nonlinear stiffness due to the stretching strain in the membrane provides a wider harvestable frequency bandwidth than conventional linear oscillators. Wideband energy harvesters are more useful for practical applications due to uncontrollable ambient vibration frequency. The load-deflection equation of the device is calculated using finite element simulation. This equation is then used in an analytical solution to estimate the nonlinear effect of the structure. A bandwidth of ~146?Hz is obtained for the fabricated device and a maximum open circuit voltage of 1.42?V, maximum power of 1.37?µW, and power density of 3.81?µW?cm?2 were measured at terminal load of 357.4?k? under an excitation acceleration of 4?g. A power output of 10.1?µW and power density of 28.1?µW?cm?2 was estimated using a synchronized switch harvesting on interface (SSHI) electrical interface with electrical quality factor of 5. In addition, the lumped element model has been employed to investigate the scaling effect on a polymeric circular diaphragm.

  1. Optimization of bandwidth of communication channels of corporate networks

    Directory of Open Access Journals (Sweden)

    G. I. Bondarenko

    2014-09-01

    Full Text Available Introduction. This article contains overview of the organization of communication between applications on the corporate network. It is stated that the main digital channel (channel B - 64 kbit/s and the primary digital channel (channel E1 the digital stream - 2048 kbit/s are used as the main channels in corporate networks. Problem areas of the functioning of the corporate network are identified. There are the rent of communication channels, which is growing rapidly with increasing the quality and speed of data transmission, and optimal use of bandwidth of communication channels. Setting of task. Optimal use of transmission channels bandwidth and minimizing the rent cost of channels is possible in two ways - the use of compression techniques of voice and video information and the application of variable structure of channels by using various-speed transmission channels. Differential pulse code modulation, adaptive differential pulse code modulation are the modern methods of speech signals processing. Organization of various-speed channels is performed in the structure of the BCC (for speech signals or PCR (for video. Suggestions for optimizing the structure of the channel signals. Proposed method of various-speed channels formation by using the channel intervals appropriate BCC (octets in the structure of signals E1 as envelopes containing various-speed channels. Channels can be selected for synchronization procedure CRC to simplify recognition of channels in the structure of E1. In this case, the minimal speed in the channel is 4 kbit/s. Conclusions. The proposed structure of envelopes is based on octet channel intervals of standard group signal of the primary group plesiochronous hierarchy E1 when transferring various-speed digital signals maximum allows to use the bandwidth at a fixed structure of channel interval, it makes possible to agree on the structure of the various-speed signals with the existing in communication networks.

  2. Bandwidth allocation for video under quality of service constraints

    CERN Document Server

    Anjum, Bushra

    2014-01-01

    We present queueing-based algorithms to calculate the bandwidth required for a video stream so that the three main Quality of Service constraints, i.e., end-to-end delay, jitter and packet loss, are ensured. Conversational and streaming video-based applications are becoming a major part of the everyday Internet usage. The quality of these applications (QoS), as experienced by the user, depends on three main metrics of the underlying network, namely, end-to-end delay, jitter and packet loss. These metrics are, in turn, directly related to the capacity of the links that the video traffic trave

  3. Introducing a Performance Model for Bandwidth-Limited Loop Kernels

    CERN Document Server

    Treibig, Jan

    2009-01-01

    We present a performance model for bandwidth limited loop kernels which is founded on the analysis of modern cache based microarchitectures. This model allows an accurate performance prediction and evaluation for existing instruction codes. It provides an in-depth understanding of how performance for different memory hierarchy levels is made up. The performance of raw memory load, store and copy operations and a stream vector triad are analyzed and benchmarked on three modern x86-type quad-core architectures in order to demonstrate the capabilities of the model.

  4. V-305 high-bandwidth analog airborne recorder/reproducer

    Science.gov (United States)

    Ludeke, Peter J.

    1993-02-01

    The V-305 High-Bandwidth Analog Airborne Recorder/Reproducer has been specifically developed to satisfy the airborne image recording requirements for various applications including high-resolution airborne reconnaissance, search and rescue operations, and surveillance. In addition, the V-305 has the flexibility to record many other types of signals such as those encountered in E-W, ELINT, and radar applications. As part of this new product's ongoing development and evaluation, NACOUS has recently performed airborne recording of infrared imagery from an AN/AAD-5 RC Infrared Linescanner. This paper describes the V-305 and the in-flight image recording results.

  5. Space-Bandwidth Capacity-Enhanced Digital Holography

    Science.gov (United States)

    Tahara, Tatsuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Matoba, Osamu; Kubota, Toshihiro

    2013-02-01

    We propose a single-shot digital holography in which the space bandwidth available for recording an object wave can be extended in an off-axis configuration. The key points of this technique are utilizing the periodicity of a digital signal and the undersampling, intentionally setting the aliasing to the recorded hologram, and conducting spatial-carrier phase-shifting interferometry and the Fourier transform method. The image quality for both large objects and fine structures can be improved by the keys. The effectiveness of the proposed technique was numerically and experimentally demonstrated. Then, the performance and the optimal angle condition were quantitatively analyzed.

  6. Flexible All-Digital Receiver for Bandwidth Efficient Modulations

    Science.gov (United States)

    Gray, Andrew; Srinivasan, Meera; Simon, Marvin; Yan, Tsun-Yee

    2000-01-01

    An all-digital high data rate parallel receiver architecture developed jointly by Goddard Space Flight Center and the Jet Propulsion Laboratory is presented. This receiver utilizes only a small number of high speed components along with a majority of lower speed components operating in a parallel frequency domain structure implementable in CMOS, and can currently process up to 600 Mbps with standard QPSK modulation. Performance results for this receiver for bandwidth efficient QPSK modulation schemes such as square-root raised cosine pulse shaped QPSK and Feher's patented QPSK are presented, demonstrating the flexibility of the receiver architecture.

  7. Efficient and Fair Bandwidth Allocation AQM Scheme for Wireless Networks

    Directory of Open Access Journals (Sweden)

    Rafe Alasem

    2010-05-01

    Full Text Available Heterogeneous Wireless Networks are considered nowadays as one of the potential areas in research and development. The traffic management’s schemes that have been used at the fusion points between the different wireless networks are classical and conventional. This paper is focused on developing a novel scheme to overcome the problem of traffic congestion in the fusion point router interconnected the heterogeneous wireless networks. The paper proposed an EF-AQM algorithm which provides an efficient and fair allocation of bandwidth among different established flows. Finally, the proposed scheme developed, tested and validated through a set of experiments to demonstrate the relative merits and capabilities of a proposed scheme

  8. Iterative Available Bandwidth Estimation for Mobile Transport Networks

    DEFF Research Database (Denmark)

    Ubeda Castellanos, Carlos; López Villa, Dimas

    2007-01-01

    Available bandwidth estimation has lately been proposed to be used for end-to-end resource management in existing and emerging mobile communication systems, whose transport networks could end up being the bottleneck rather than the air interface. Algorithms for admission control, handover and adaptive QoS management could take into account such estimations, which may lead to an overall system performance improvement. This paper introduces two new iterative algorithms (Zoom and Adaptive pathChirp) for network load monitoring that can be combined with a linear least squares fitting achieving reliable estimations without causing congestion collapse. Their performance is evaluated in a simulated UTRAN Long Term Evolution backhaul.

  9. 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.

  10. 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.

  11. Systems with selective overflow and change of bandwidth

    DEFF Research Database (Denmark)

    Iversen, Villy Bæk

    2012-01-01

    We consider a loss system with n channels and a finite or infinite overflow group, which is offered N different services, all having Poisson arrival processes. All calls have same bandwidth demand and mean service time, but the mean service time may be different on the primary group and the overflow group, corresponding to data traffic with different bandwidth allocation on primary (micro-cell = femto-cell) and overflow group (macro-cell = LTE-cell). Then using a result of Wallström we can calculate the Binomial moments of the total overflow traffic. Given a certain number of busy channels on the overflow group, we show by balance equations that the number of calls of each service will be Multinomial distributed with probabilities proportional with the arrival rates. Using a recent result of Newcomer & al, we then find moments (done up to fourth order) of individual overflow streams or any combinations of overflow streams. Thus we can find the correlation between services and for example the moments of some traffic streams which may overflow to one system, whereas other traffic streams may be blocked or overflow to another system.

  12. 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...

  13. The Effect of Pulse Shaping QPSK on Bandwidth Efficiency

    Science.gov (United States)

    Purba, Josua Bisuk Mubyarto; Horan, Shelia

    1997-01-01

    This research investigates the effect of pulse shaping QPSK on bandwidth efficiency over a non-linear channel. This investigation will include software simulations and the hardware implementation. Three kinds of filters: the 5th order Butterworth filter, the 3rd order Bessel filter and the Square Root Raised Cosine filter with a roll off factor (alpha) of 0.25,0.5 and 1, have been investigated as pulse shaping filters. Two different high power amplifiers, one a Traveling Wave Tube Amplifier (TWTA) and the other a Solid State Power Amplifier (SSPA) have been investigated in the hardware implementation. A significant improvement in the bandwidth utilization (rho) for the filtered data compared to unfiltered data through the non-linear channel is shown in the results. This method promises strong performance gains in a bandlimited channel when compared to unfiltered systems. This work was conducted at NMSU in the Center for Space Telemetering, and Telecommunications Systems in the Klipsch School of Electrical and Computer Engineering Department and is supported by a grant from the National Aeronautics and Space Administration (NASA) NAG5-1491.

  14. A Bandwidth Allocation Model Provisioning Framework with Autonomic Characteristics

    Directory of Open Access Journals (Sweden)

    Rafael F. Reale

    2013-11-01

    Full Text Available The Bandwidth Allocation Models (MAM, RDM, G-RDM and AllocTC-Sharing are managementalternatives currently available which propose different resource (bandwidth allocation strategies inmultiservice networks. The BAM adoption by a network is typically a management choice andconfiguration task executed by the network operations and management system setup in a static or nearlystatic way. This paper proposes and explores the alternative ofallowing BAM definition and configurationon a more dynamic way. In effect, one of the basic motivations towards BAM dynamic allocation is the factthat multiservice networks characteristics (traffic loadmay change considerably in daily networkoperation and, as such, some dynamics in BAM allocation should be introduced in order to improveperformance. A framework is presented supporting BAM dynamicallocation. The framework adopts anOpenFlow-based software-defined networking (SDN implementation approach in order to supportscalability issues with a centralized controller and managementnetwork view. The framework architecturealso supports the implementation of some autonomic characteristics which, in brief, look for improving andfacilitating the decision-making process involved with BAM provisioning in a multiservice network. Aproof of concept is presented evaluating different BAM performance under different traffic loads in order todemonstrate the framework strategy adopted.

  15. Bandwidth Optimization in Centralized WLANs for Different Traffic Types

    Directory of Open Access Journals (Sweden)

    Haines RJ

    2007-01-01

    Full Text Available Allocating bandwidth between different forms of coexisting traffic (such as web-browsing, streaming, and telephony within a wireless LAN is a challenging and interesting problem. Centralized coordination functions in wireless LANs offer several advantages over distributed approaches, having the benefit of a system overview at the controller, but obtaining a stable configuration of bandwidth allocation for the system is nontrivial. We present, review, and compare different mechanisms to achieve this end, and a number of different means of obtaining the configurations themselves. We describe an analytical model of the system under consideration and present two mathematical approaches to derive solutions for any system configuration and deployment, along with an adaptive feedback-based solution. We also describe a comprehensive simulation-based model for the problem, and a prototype that allows comparison of these approaches. Our investigations demonstrate that a self-adaptive dynamic approach far outperforms any static scheme, and that using a mathematical model to produce the configurations themselves confers several advantages.

  16. A wide bandwidth electrostatic field sensor for lightning research

    Science.gov (United States)

    Zaepfel, Klaus P.

    1989-01-01

    Data obtained from UHF radar observation of direct-lightning strikes to the NASA F-106B aircraft have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero bolts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The system was implemented with four shutter-type field mills located at strategic points on the aircraft. The bandwidth of the system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite difference time-domain electromagnetic computer code.

  17. A wide bandwidth electrostatic field sensor for lightning research

    Science.gov (United States)

    Zaepfel, K. P.

    1986-06-01

    Data obtained from UHF Radar observation of direct-lightning strikes to the NASA F-106B airplane have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero volts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The new system was implemented with four shutter-type field mills located at strategic points on the airplane. The bandwidth of the new system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 Hz to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite-difference time-domain electromagnetic computer code.

  18. Modulation bandwidth of spin torque oscillators under current modulation

    Energy Technology Data Exchange (ETDEWEB)

    Quinsat, M. [Univ. Grenoble Alpes, F-38054 Grenoble (France); CEA, INAC-SPINTEC, F-38054 Grenoble (France); CNRS, SPINTEC, F-38054 Grenoble (France); CEA-LETI MINATEC-CAMPUS, 17 F-38054 Grenoble (France); Garcia-Sanchez, F.; Jenkins, A. S.; Buda-Prejbeanu, L. D.; Dieny, B.; Ebels, U. [Univ. Grenoble Alpes, F-38054 Grenoble (France); CEA, INAC-SPINTEC, F-38054 Grenoble (France); CNRS, SPINTEC, F-38054 Grenoble (France); Tiberkevich, V. S.; Slavin, A. N. [Department of Physics, Oakland University, Rochester, Michigan 48309 (United States); Zeltser, A.; Katine, J. A. [HGST, San Jose, California 95193 (United States); Cyrille, M.-C. [Univ. Grenoble Alpes, F-38054 Grenoble (France); CEA-LETI MINATEC-CAMPUS, 17 F-38054 Grenoble (France)

    2014-10-13

    For practical applications of spin torque nano-oscillators (STNO), one of the most critical characteristics is the speed at which an STNO responds to variations of external control parameters, such as current or/and field. Theory predicts that this speed is limited by the amplitude relaxation rate ?{sub p} that determines the timescale over which the amplitude fluctuations are damped out. In this study, this limit is verified experimentally by analyzing the amplitude and frequency noise spectra of the output voltage signal when modulating an STNO by a microwave current. In particular, it is shown that due to the non-isochronous nature of the STNO the amplitude relaxation rate ?{sub p} determines not only the bandwidth of an amplitude modulation, but also the bandwidth of a frequency modulation. The presented experimental technique will be important for the optimisation of the STNO characteristics for applications in telecommunications or/and data storage and is applicable even in the case when the STNO output signal is only several times higher than noise.

  19. Punctured Turbo Codes for Bandwidth-efficient Transmission

    Directory of Open Access Journals (Sweden)

    Shobha Rekh

    2006-10-01

    Full Text Available Turbo codes are the error-coding schemes applied nowadays in wireless networks. In navalapplications, the information is mostly sent through wireless networks and the data is moreprone to noise. Since very important data has to be communicated, it is necessary to get backthe original data in the receiver. In military applications also, the soldiers wear electronic jacketswhich are connected by wireless networks. In such applications, the data loss is not affordableand there is also a need to utilise the bandwidth efficiently through puncturing by means ofwhich certain bits are deleted before transmission from the output of encoder. By means of thispunctured turbo codes, bandwidth-efficient coding is achieved. Hence, it is necessary to designturbo codes with an efficient puncturing pattern so that the performance of the punctured codeis also improved in spite of deletion of few bits before transmission. This paper deals in choosingthe puncturing patterns that lead to systematic rate-compatible punctured turbo codes (RCPTCswhich also give a reduction in bit-error rate. The design criterion for choosing the best puncturingpatterns is based on the minimum weight of code words and their multiplicities. The best puncturingpattern chosen is tested for its performance by simulating turbo codes for an additive whiteGaussian noise (AWGN channel. Compared with the existing puncturing pattern, the patternproposed is able to achieve a gain of 0.5 dB at a bit-error rate of 10-3.

  20. Bandwidth Estimation to Provide QoS Routing in MANET

    Directory of Open Access Journals (Sweden)

    Ms. Swati Kamra,

    2013-04-01

    Full Text Available In mobile ad hoc networks (MANETs, the provision of quality of service (QoS guarantees is much more challenging than in wire line networks, mainly due to node mobility, multi-hop communications, contention for channel access, and a lack of central coordination. QoS guarantees are required by most multimedia and other time- or error-sensitive applications. The difficulties in the provision of such guarantees have limited the usefulness of MANETs. However, in the last decade, much research attention has focused on providing QoS assurances in MANET protocols. The QoS routing protocol is an integral part of any QoS solution. We propose a QoS routing protocol is the use of the approximate bandwidth estimation to react to network traffic. Our approach implements Admission control and feedback scheme by using two bandwidth estimation methods (Hello and Listen. We simulate our QoS- routing protocol for nodes running the IEEE 802.11 medium access control. Results of our experiments show those Comparisons among Hello and Listen Methods with the Qos metrics.

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

    OpenAIRE

    Ziyi Fu; Juanjuan Bai; Qiang Wang

    2012-01-01

    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, ...

  2. ENERGY AND BANDWIDTH INFLUENCE ON EFFICIENCY IN WIRELESS NETWORKS: A REVIEW

    OpenAIRE

    PROF. R.K SINGH,; TANU PREET SINGH

    2010-01-01

    In this paper, we review the efficiency of wireless ad hoc networks. The wireless networks efficiency deals with the bandwidth and the energy efficiency of the networks that depends upon the energy supply of the nodes. This energy and the bandwidth related to it are the major constraints to be considered in this paper. The network comprises of the nodes that consist of different channels for transmission purpose and these are the major areas for bandwidth efficiency. The energy concerned is t...

  3. A Novel Framework for Distributed Dynamic Bandwidth Allocation in EPONWiMAX Networks

    OpenAIRE

    Ramya, S; Dr.N.Nagarajan; Dr.B.Kaarthick

    2014-01-01

    In Ethernet Passive Optical Networks (EPON), allocation of bandwidth to the Optical Network Units (ONU) is a critical issue in determining the performance of the network. The resource allocation process in EPON is carried out by the Dynamic Bandwidth Allocation (DBA) algorithm. The onus of resource allocation or DBA estimation is bore solely by Optical Line Terminal (OLT) which results in more idle time at the OLT, thereby resulting in wastage of bandwidth and increased delay in data tr...

  4. An Orthogonal Frequency Division Multiplexing Radar Waveform with a Large Time-bandwidth Product (Short Communication

    Directory of Open Access Journals (Sweden)

    Wen-Qin Wang

    2012-11-01

    Full Text Available This paper proposes a practical orthogonal frequency division multiplexing (OFDM chirp diverse waveform with a large time-bandwidth product for new generation radar systems. Besides large time-bandwidth product and implementation simplicity, the OFDM chirp diverse waveform have good ambiguity function performance in range resolution and doppler resolution. Although the spectra are not uniform across the bandwidth like conventional chirp waveforms, the bandwidth is covered with no visible gaps.Defence Science Journal, 2012, 62(6, pp.427-430, DOI:http://dx.doi.org/10.14429/dsj.62.2100

  5. Bandwidth allocation strategy for traffic systems of scale-free network

    Energy Technology Data Exchange (ETDEWEB)

    Ling Xiang [School of Engineering Science, University of Science and Technology of China, Hefei 230026 (China); Hu MaobBin, E-mail: humaobin@ustc.edu.c [School of Engineering Science, University of Science and Technology of China, Hefei 230026 (China); Department of Mathematics and Statistics, Curtin University of Technology, Perth WA6845 (Australia); Du Wenbo [School of Computer Science and Technology, University of Science and Technology of China, Hefei 230026 (China); Jiang Rui [School of Engineering Science, University of Science and Technology of China, Hefei 230026 (China); Wu Yonghong [Department of Mathematics and Statistics, Curtin University of Technology, Perth WA6845 (Australia); Wu Qingsong [School of Engineering Science, University of Science and Technology of China, Hefei 230026 (China)

    2010-11-01

    In this Letter, the bandwidth resource allocation strategy is considered for traffic systems of complex networks. With a finite resource of bandwidth, an allocation strategy with preference parameter {alpha} is proposed considering the links importance. The performance of bandwidth allocation strategy is studied for the local routing protocol and the shortest path protocol. When important links are slightly favored in the bandwidth allocation, the system can achieve the optimal traffic performance for the two routing protocols. For the shortest path protocol, we also give a method to estimate the network traffic capacity theoretically.

  6. Bandwidth allocation strategy for traffic systems of scale-free network

    International Nuclear Information System (INIS)

    In this Letter, the bandwidth resource allocation strategy is considered for traffic systems of complex networks. With a finite resource of bandwidth, an allocation strategy with preference parameter ? is proposed considering the links importance. The performance of bandwidth allocation strategy is studied for the local routing protocol and the shortest path protocol. When important links are slightly favored in the bandwidth allocation, the system can achieve the optimal traffic performance for the two routing protocols. For the shortest path protocol, we also give a method to estimate the network traffic capacity theoretically.

  7. Hybrid grating reflector with high reflectivity and broad bandwidth

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza; Park, Gyeong Cheol

    2014-01-01

    We suggest a new type of grating reflector denoted hybrid grating (HG) which shows large reflectivity in a broad wavelength range and has a structure suitable for realizing a vertical cavity laser with ultra-small modal volume. The properties of the grating reflector are investigated numerically and explained. The HG consists of an un-patterned III-V layer and a Si grating. The III-V layer has a thickness comparable to the grating layer, introduces more guided mode resonances and significantly increases the bandwidth of the reflector compared to the well-known high-index-contrast grating (HCG). By using an active III-V layer, a laser can be realized where the gain region is integrated into the mirror itself

  8. Techniques in molecular spectroscopy: from broad bandwidth to high resolution

    Science.gov (United States)

    Cossel, Kevin C.

    This thesis presents a range of different experiments all seeking to extended the capabilities of molecular spectroscopy and enable new applications. The new technique of cavity-enhanced direct frequency comb spectroscopy (CE-DFCS) provides a unique combination of broad bandwidth, high resolution, and high sensitivity that can be useful for a wide range of applications. Previous demonstrations of CE-DFCS were confined to the visible or near-infrared and operated over a limited bandwidth: for many applications it is desirable to increase the spectral coverage and to extend to the mid-infrared where strong, fundamental vibrational modes of molecules occur. There are several key requirements for CE-DFCS: a frequency comb source that provides broad bandwidth and high resolution, an optical cavity for high sensitivity, and a detection system capable of multiplex detection of the comb spectrum transmitted through the cavity. We first discuss comb sources with emphasis on the coherence properties of spectral broadening in nonlinear fiber and the development of a high-power frequency comb source in the mid-infrared based on an optical-parametric oscillator (OPO). To take advantage of this new mid-infrared comb source for spectroscopy, we also discuss the development of a rapid-scan Fourier-transform spectrometer (FTS). We then discuss the first demonstration of CE-DFCS with spectrally broadened light from a highly nonlinear fiber with the application to measurements of impurities in semiconductor manufacturing gases. We also cover our efforts towards extending CE-DFCS to the mid-infrared using the mid-infrared OPO and FTS to measure ppb levels of various gases important for breath analysis and atmospheric chemistry and highlight some future applications of this system. In addition to the study of neutral molecules, broad-bandwidth and high-resolution spectra of molecular ions are useful for astrochemistry where many of the observed molecules are ionic, for studying molecules such as CH5 + with highly non-classical behavior, and for tests of fundamental physics. We have developed a new technique---frequency comb velocity-modulation spectroscopy---that is the first system to enable rapid, broadband spectroscopy of molecular ions with high resolution. We have demonstrated the ability to record 150 cm-1 of spectra consisting of 45,000 points in 30 minutes and have used this system to record over 1000 cm-1 of spectra of HfF+ in the near-infrared around 800 nm. After improvements, the system can now cover more than 3250 cm-1 (700-900 nm). We have combined this with standard velocity-modulation spectroscopy to measure and analyze 19 ro-vibronic bands of HfF+. These measurements enabled precision spectroscopy of trapped HfF + for testing time-reversal symmetry. For this experiment, we perform Ramsey spectroscopy between spin states in the metastable 3Delta 1 level to look for a permanent electric dipole moment of the electron with what we believe is the narrowest line observed in a molecular system (Fourier limited with 500 ms of coherence time). The long coherence time is a major advantage of using ions, but there are also some added complexities. We discuss various aspects metastable state preparation, state detection, and spectroscopy in a rotating frame (due to the necessary rotating electric bias field) that were particular challenging. In addition, we discuss limits to the coherence time---in particular, ion-ion collisions---as well as the sensitivity of the current measurements and provide a path towards a new limit on the electric dipole moment of the electron.

  9. A Hybrid ACO Approach to the Matrix Bandwidth Minimization Problem

    Science.gov (United States)

    Pintea, Camelia-M.; Cri?an, Gloria-Cerasela; Chira, Camelia

    The evolution of the human society raises more and more difficult endeavors. For some of the real-life problems, the computing time-restriction enhances their complexity. The Matrix Bandwidth Minimization Problem (MBMP) seeks for a simultaneous permutation of the rows and the columns of a square matrix in order to keep its nonzero entries close to the main diagonal. The MBMP is a highly investigated {NP}-complete problem, as it has broad applications in industry, logistics, artificial intelligence or information recovery. This paper describes a new attempt to use the Ant Colony Optimization framework in tackling MBMP. The introduced model is based on the hybridization of the Ant Colony System technique with new local search mechanisms. Computational experiments confirm a good performance of the proposed algorithm for the considered set of MBMP instances.

  10. Impedance Bandwidth and Gain Improvement for Microstrip Antenna Using Metamaterials

    Directory of Open Access Journals (Sweden)

    H. Xiong

    2012-12-01

    Full Text Available An improved ultra-wideband (UWB and high gain rectangular antenna is specifically designed in this paper using planar-patterned metamaterial concepts. The antenna has isolated triangle gaps and crossed gaps etched on the metal patch and ground plane, respectively. By changing the pattern on the ground, the impedance matching characteristics of the antenna are much better. The -10 dB impedance bandwidth of the proposed antenna is 3.85–15.62 GHz, which is about 267% broader. The proposed antenna has an average gain of 5.42 dB and the peak is 8.36 dB at 13.5 GHz. Compared with the original one, the gain of the proposed antenna improved about 1.4 dB. Moreover, the size is reduced slightly. Simulated and experimental results obtained for this antenna show that it exhibits good radiation behavior within the UWB frequency range

  11. Performance evaluation of a high-bandwidth timing module

    International Nuclear Information System (INIS)

    The ability to generate highly precise timing signals is essential for the operation of particle accelerators, particularly so in future linear colliders. As a tool to generate precise fixed delays, a module called TD-2.1 has been developed for use at the ATF (Accelerator Test Facility). TD-2.1 is an improved version of a previous module called TD-2, developed for the TRISTAN accelerator. The new version can be used at clock frequencies of up to 1.5 GHz, almost three times the bandwidth of the previous version. Since TD-2.1 is applied in many places to synchronize the ATF accelerator operation, high reliability and stability (low jitter) are essential. The long-term stability and timing jitter of the module were evaluated. The jitter was found to be around 5 ps within the operating range. Stable operation of the module was verified in long-term tests. (author)

  12. Wide-Bandwidth Capture of Wire-Scanner Signals

    Energy Technology Data Exchange (ETDEWEB)

    Gruchalla, Michael E. [Los Alamos National Laboratory; Gilpatrick, John D. [Los Alamos National Laboratory; Sedillo, James Daniel [Los Alamos National Laboratory; Martinez, Derwin [Los Alamos National Laboratory

    2012-05-16

    Integrated charge collected on the sense wires of wire-scanner systems utilized to determine beam profile is generally the parameter of interest. The LANSCE application requires capturing the charge information macropulse-by-macropulse with macropulse lengths as long as 700 {micro}s at a maximum macropulse rate of 120 Hz. Also, for the LANSCE application, it is required that the integration be performed in a manner that does not require integrator reset between macropulses. Due to the long macropulse which must be accommodated and the 8.33 ms minimum pulse period, a simple R-C integrator cannot be utilized since there is insufficient time between macropulses to allow the integrator to adequately recover. The application of wide analog bandwidth to provide accurate pulse-by-pulse capture of the wire signals with digital integration of the wire signals to determine captured charge at each macropulse in applications with comparatively long macropulses and high pulse repetition rates is presented.

  13. Wide-Bandwidth Capture of Wire-Scanner Signals

    International Nuclear Information System (INIS)

    Integrated charge collected on the sense wires of wire-scanner systems utilized to determine beam profile is generally the parameter of interest. The LANSCE application requires capturing the charge information macropulse-by-macropulse with macropulse lengths as long as 700 (micro)s at a maximum macropulse rate of 120 Hz. Also, for the LANSCE application, it is required that the integration be performed in a manner that does not require integrator reset between macropulses. Due to the long macropulse which must be accommodated and the 8.33 ms minimum pulse period, a simple R-C integrator cannot be utilized since there is insufficient time between macropulses to allow the integrator to adequately recover. The application of wide analog bandwidth to provide accurate pulse-by-pulse capture of the wire signals with digital integration of the wire signals to determine captured charge at each macropulse in applications with comparatively long macropulses and high pulse repetition rates is presented.

  14. Adaptive data filtering of inertial sensors with variable bandwidth.

    Science.gov (United States)

    Alam, Mushfiqul; Rohac, Jan

    2015-01-01

    MEMS (micro-electro-mechanical system)-based inertial sensors, i.e., accelerometers and angular rate sensors, are commonly used as a cost-effective solution for the purposes of navigation in a broad spectrum of terrestrial and aerospace applications. These tri-axial inertial sensors form an inertial measurement unit (IMU), which is a core unit of navigation systems. Even if MEMS sensors have an advantage in their size, cost, weight and power consumption, they suffer from bias instability, noisy output and insufficient resolution. Furthermore, the sensor's behavior can be significantly affected by strong vibration when it operates in harsh environments. All of these constitute conditions require treatment through data processing. As long as the navigation solution is primarily based on using only inertial data, this paper proposes a novel concept in adaptive data pre-processing by using a variable bandwidth filtering. This approach utilizes sinusoidal estimation to continuously adapt the filtering bandwidth of the accelerometer's data in order to reduce the effects of vibration and sensor noise before attitude estimation is processed. Low frequency vibration generally limits the conditions under which the accelerometers can be used to aid the attitude estimation process, which is primarily based on angular rate data and, thus, decreases its accuracy. In contrast, the proposed pre-processing technique enables using accelerometers as an aiding source by effective data smoothing, even when they are affected by low frequency vibration. Verification of the proposed concept is performed on simulation and real-flight data obtained on an ultra-light aircraft. The results of both types of experiments confirm the suitability of the concept for inertial data pre-processing. PMID:25648711

  15. Small signal microwave amplifier design solutions

    CERN Document Server

    Grosch, Theodore

    2000-01-01

    This book explains techniques and examples for designing stable amplifiers for high-frequency applications in which the signal is small and the amplifier circuit is linear. An in-depth discussion of linear network theory provides the foundation needed to develop actual designs. Examples throughout the book will show you how to apply the knowledge gained in each chapter leading to the complex design of low noise amplifiers. Many exercises at the end of each chapter will help students to practice their skills. The solutions to these design problems are available in an accompanying solutions book

  16. Regulating Bandwidth Flow Estimation and Control for Wired/Wireless Networks

    Directory of Open Access Journals (Sweden)

    Pallavi Sharma

    2012-01-01

    Full Text Available In this topic, an analysis will be made on the problems faced by bandwidth constrained applications which comes under networking domain. For bandwidth constrained applications, a proper monitoring of available bandwidth is an important factor to avoid degradation in performance while execution. Such application example could be video or voice chat on Internet , which consumes more bandwidth and its overall performance is bandwidth constraint. After the implementation of 802.11e Wireless Sensor Networks are capable to provide good level of QoS but research works are not much for improving performance of bandwidth constraint applications by checking sufficiency of bandwidth available in transmission route. We propose to design and develop a system for 802.11 based ad-hoc networks, which estimate the network traffic bandwidth and control the flow of traffic on given channels. Our research would be capable to work on both wired and wireless ad-hoc network, On top of it, It would be able to show the simulation results on multiple computers.

  17. Gigabit Passive Optical Networks (GPON the Ultimate Solution for Large Bandwidth

    Directory of Open Access Journals (Sweden)

    A.ManikantaSitaram

    2012-11-01

    Full Text Available The demand for bandwidth has increased drastically. So optical transmission has got more importance in access networks. The upcoming features like IPTV, High speed internet(HSI, Video on demand(VOD, online gaming are confronting large bandwidth at the customer end.The demand of bandwidth can be satisfied by XDSL, but the distance is restricted by using this type of technique. So we can use optical transmission for achieving large bandwidth by using passive optical networks(PON. One of the most advanced PON solution is Gigabit PON (GPON. This is the most widely used solution where there is a requirement of large bandwidth This paper provides an overview of GPONfeatures, transmission mechanism, optical splitting and power budget.

  18. Design and fabrication of bandwidth tunable HTS transmit filter using ?-shaped waveguides

    International Nuclear Information System (INIS)

    We have developed a method for tuning the bandwidth of a high-temperature superconducting (HTS) microstrip filter. Several ?-shaped waveguides are placed between the resonators, and the bandwidth is tuned in discrete steps by changing the switch states of the waveguides, which changes the coupling coefficient between the resonators. The filter contains 3-pole half-wavelength straight-line resonators and two ?-shaped waveguides for bandwidth tuning. It also has several electrical pads distributed around the feed lines for trimming after tuning. The filter was fabricated by depositing YBa2Cu3O7 thin film on an MgO substrate and has a measured center frequency of 5.17 GHz and bandwidth of 220 MHz. Use of the ?-shaped waveguides to adjust the coupling coefficients and the electrical pads to adjust the external quality factors resulted in 80-MHz bandwidth tuning without increased insertion loss.

  19. Design and enhancement bandwidth rectangular patch antenna using single trapezoidal slot technique

    Directory of Open Access Journals (Sweden)

    Karim A. Hamad

    2012-03-01

    Full Text Available Microstrip patch antennas has some drawbacks of low efficiency, narrow bandwidth (3-6 % of the central frequency, its bandwidth is limited to a few percent which is not enough for most of the wireless communication systems nowadays. In this paper one of the efficient methods used for the enhancement of patch antenna Bandwidth is the loading of microstrip patch Antenna with a trapezoidal slot. Microstrip patch antenna that meets the requirement of operation at 2.4 GHZ, the proposed configurations is simulated and analyzed using (CST- 2010 software package. The VSWR, input impedance‚ radiation patterns and S11 performance are used for the analysis of the different configurations. The simulated results for trapezoidal slot give bandwidth of 287.2 MHZ (11.93% fractional bandwidth. Feed point on the patch that gives a good Match of 50 ohm.

  20. Revealing statistical properties of quasi-CW fibre lasers in bandwidth-limited measurements.

    Science.gov (United States)

    Gorbunov, O A; Sugavanam, S; Churkin, D V

    2014-11-17

    We introduce a general technique how to reveal in experiments of limited electrical bandwidth which is lower than the optical bandwidth of the optical signal under study, whether the statistical properties of the light source obey Gaussian distribution or mode correlations do exist. To do that one needs to perform measurements by decreasing the measurement bandwidth. We develop a simple model of bandwidth-limited measurements and predict universal laws how intensity probability density function and intensity auto-correlation function of ideal completely stochastic source of Gaussian statistics depend on limited measurement bandwidth and measurement noise level. Results of experimental investigation are in good agreement with model predictions. In particular, we reveal partial mode correlations in the radiation of quasi-CW Raman fibre laser. PMID:25402047

  1. QoS routing via multiple paths using bandwidth reservation

    Energy Technology Data Exchange (ETDEWEB)

    Rao, N.S.V.; Batsell, S.G.

    1998-01-01

    The authors address the problem of computing a multipath, consisting of possibly overlapping paths, to transmit data from the source node s to the destination node d over a computer network while ensuring deterministic bounds on end-to-end delay or delivery rate.They consider two generic routing problems within the framework wherein bandwidth can be reserved, and guaranteed, once reserved, on various links of the communication network. The first problem requires that a message of finite length be transmitted from s to d within {tau} units of time. The second problem requires that a sequential message of r units be transmitted at a rate of {eta} such that maximum time difference between two units that are received out of order is no more than q. They propose a polynomial-time algorithm to the first problem based on an adaptation of the classical Ford-Fulkerson`s method. They present simulation results to illustrate the applicability of the proposed algorithm. They show the second problem to be NP-complete, and propose a polynomial-time approximately solution.

  2. QoS routing via multiple paths using bandwidth reservation

    Energy Technology Data Exchange (ETDEWEB)

    Rao, N.S.V.; Batsell, S.G.

    1997-11-01

    The authors address the problem of computing a multipath, consisting of possibly overlapping paths, to transmit data from the source node s to the destination node d over a computer network while ensuring deterministic bounds on end-to-end delay or delivery rate. They consider two generic routing problems within the framework wherein bandwidth can be reserved, and guaranteed, once reserved, on various links of the communication network. The first problem requires that a message of finite length be transmitted from s to d within {tau} units of time. The second problem requires that a sequential message of r units be transmitted at a rate of {eta} such that maximum time difference between two units that are received out of order is no more than q. They propose a polynomial-time algorithm to the first problem based on an adaptation of the classical Ford-Fulkerson`s method. They present simulation results to illustrate the applicability of the proposed algorithm. They show the second problem to be NP-complete and propose a polynomial-time approximate solution.

  3. Imaging bandwidth of the tapping mode atomic force microscope probe

    Science.gov (United States)

    Kokavecz, János; Marti, Othmar; Heszler, Péter; Mechler, Ádám

    2006-04-01

    In this work we report a comprehensive experimental and computational study of the dynamical behavior of the tapping mode atomic force microscope (AFM) probe in interaction with the force field of a sample surface. To address the nonlinear nature of the probe dynamics, we apply describing function method. We established that the corner frequency of the low pass describing function of the probe is sensitive to the modulation amplitude and is generally higher than predicted by linear — force gradient — approximation. We show that large tip apex radii and high values of surface Young’s moduli can introduce a resonant amplitude transfer, which could lead to image distortion and system instabilities. We demonstrate that the oscillating amplitude of the probe far from the surface and during imaging, and the ratio of these two (setpoint) have an influence on the describing function of the probe similar to that of the quality factor. Accordingly, expert control of these parameters is as effective as active Q control in improving the imaging bandwidth of the tapping mode AFM.

  4. Automatic Bandwidth Adjustment for Content Distribution in MPLS Networks

    Directory of Open Access Journals (Sweden)

    D. Moltchanov

    2008-04-01

    Full Text Available Aggregates of real-time traffic may experience changes in their statistical characteristics often manifesting non stationary behavior. In multi protocol label switching (MPLS networks this type of the traffic is assigned constant amount of resources. This may result in ineffective usage of resources when the load is below than expected or inappropriate performance when the load is higher. In this paper we propose new algorithm for dynamic resource adaptation to temporarily changing traffic conditions. Assuming that network nodes may reallocate resources on-demand using automatic bandwidth adjustment capability of MPLS framework, the proposed algorithm, implemented at ingress MPLS nodes, dynamically decides which amount of resources is currently sufficient to handle arriving traffic with given performance metrics. This decision is then communicated to interior MPLS nodes along the label switched path. As a basic tool of the algorithm we use change-point statistical test that signals time instants at which statistical characteristics of traffic aggregates change. The major advantage of the proposed approach is that it is fully autonomous, that is, network nodes do not need any support from hosts in terms of resource reservation requests. The proposed algorithm is well suited for traffic patterns experiencing high variability, especially, for non stationary type of the traffic.

  5. One "shape" fits all: the orientation bandwidth of contour integration.

    Science.gov (United States)

    Hansen, Bruce C; May, Keith A; Hess, Robert F

    2014-01-01

    The ability of human participants to integrate fragmented stimulus elements into perceived coherent contours (amidst a field of distracter elements) has been intensively studied across a large number of contour element parameters, ranging from luminance contrast and chromaticity to motion and stereo. The evidence suggests that contour integration performance depends on the low-level Fourier properties of the stimuli. Thus, to understand contour integration, it would be advantageous to understand the properties of the low-level filters that the visual system uses to process contour stimuli. We addressed this issue by examining the role of stimulus element orientation bandwidth in contour integration, a previously unexplored area. We carried out three psychophysical experiments, and then simulated all of the experiments using a recently developed two-stage filter-overlap model whereby the contour grouping occurs by virtue of the overlap between the filter responses to different elements. The first stage of the model responds to the elements, while the second stage integrates the responses along the contour. We found that the first stage had to be fairly broadly tuned for orientation to account for our results. The model showed a very good fit to a large data set with relatively few free parameters, suggesting that this class of model may have an important role to play in helping us to better understand the mechanisms of contour integration. PMID:25406162

  6. Modelamiento y análisis de pequeña señal de un generador de inducción y un STATCOM conectados a un sistema de potencia / Modeling and analysis of a small signal of an induction generator and a STATCOM connected to a power system

    Scientific Electronic Library Online (English)

    Carlos David, Zuluaga Ríos; Alfonso, Alzate Gómez.

    2011-07-01

    Full Text Available En este documento se presenta el modelamiento y análisis de pequeña señal de un generador de inducción (IG) y un compensador síncrono estático (STATCOM), conectados a un barraje infinito, que representa un sistema de potencia; el IG es modelado como un sistema de quinto orden y se le acopla un STATC [...] OM que es estudiado como un modelo de primer orden. El comportamiento dinámico fue simulado y comparado usando MATLAB/Simulink, bajo dos condiciones de perturbación: una variación en el torque de la máquina y una variación en la tensión del barraje infinito debido a un fallo en este punto. Las respuestas obtenidas por el software reflejan que el compensador actúa de forma adecuada, contrarrestando variaciones en potencia y tensión. Cabe resaltar que se debe agregar una etapa de sintonización de parámetros para mejorar las respuestas obtenidas. Abstract in english This paper presents the modeling and small-signal analysis of an induction generator (IG) and a static synchronous compensator (STATCOM) connected to an infinite bus bar, representing a power system, the IG is modeled as ffith-order system and is coupled to a STATCOM is studied as a model of first o [...] rder. The dynamic behavior was simulated and compared using MATLAB/ Simulink, two conditions of disturbance: a variation in the torque of the machine and a variation in the infinite bus bar voltage because of a failure at this point. The responses obtained by the software show that the compensator acts appropriately counteracting power and voltage variations. Significantly, it must add a stage of tuning parameters to improve the responses.

  7. Modeling small-signal response of GaN-based metal-insulator-semiconductor high electron mobility transistor gate stack in spill-over regime: Effect of barrier resistance and interface states

    Science.gov (United States)

    Capriotti, M.; Lagger, P.; Fleury, C.; Oposich, M.; Bethge, O.; Ostermaier, C.; Strasser, G.; Pogany, D.

    2015-01-01

    We provide theoretical and simulation analysis of the small signal response of SiO2/AlGaN/GaN metal insulator semiconductor (MIS) capacitors from depletion to spill over region, where the AlGaN/SiO2 interface is accumulated with free electrons. A lumped element model of the gate stack, including the response of traps at the III-N/dielectric interface, is proposed and represented in terms of equivalent parallel capacitance, Cp, and conductance, Gp. Cp -voltage and Gp -voltage dependences are modelled taking into account bias dependent AlGaN barrier dynamic resistance Rbr and the effective channel resistance. In particular, in the spill-over region, the drop of Cp with the frequency increase can be explained even without taking into account the response of interface traps, solely by considering the intrinsic response of the gate stack (i.e., no trap effects) and the decrease of Rbr with the applied forward bias. Furthermore, we show the limitations of the conductance method for the evaluation of the density of interface traps, Dit, from the Gp/? vs. angular frequency ? curves. A peak in Gp/? vs. ? occurs even without traps, merely due to the intrinsic frequency response of gate stack. Moreover, the amplitude of the Gp/? vs. ? peak saturates at high Dit, which can lead to underestimation of Dit. Understanding the complex interplay between the intrinsic gate stack response and the effect of interface traps is relevant for the development of normally on and normally off MIS high electron mobility transistors with stable threshold voltage.

  8. Analysis of TCP in Networks with Small Buffering Capacity and Large Bandwidth-Delay Product

    OpenAIRE

    Barakat, Chadi; Altman, Eitan

    1998-01-01

    It is well known that inefficiencies occur in the operation of TCP when the bandwidth delay product of the network is large compared to its buffering capacity. A central reason for that is a cyclic behavior of the protocol in which two consecutive slow-start phases appear in each cycle [5,1]. This results in low throughput and under-utilization of the available bandwidth. We show in this paper that, for an even larger ratio between the bandwidth-delay product and the buffer size, which is typ...

  9. Increasing the bandwidth of resonant gravitational antennas The case of Explorer

    CERN Document Server

    Astone, P; Bassan, M; Carelli, P; Cavallari, Giorgio; Coccia, E; Cosmelli, C; D'Antonio, S; Fafone, V; Fauth, A C; Federici, G; Giordano, G; Marini, A; Minenkov, Y; Modena, I; Modestino, G; Moleti, A; Pallottino, G V; Pizzella, G; Quintieri, L; Rocchi, A; Ronga, F; Terenzi, R; Torrioli, G; Visco, M; 10.1103/PhysRevLett.91.111101

    2003-01-01

    Resonant gravitational wave detectors with an observation bandwidth of tens of hertz are a reality: the antenna Explorer, operated at CERN by the ROG collaboration, has been upgraded with a new read-out. In this new configuration, it exhibits an unprecedented useful bandwidth: in over 55 Hz about its frequency of operation of 919 Hz the spectral sensitivity is better than 10^{-20} /sqrt(Hz) . We describe the detector and its sensitivity and discuss the foreseable upgrades to even larger bandwidths.

  10. Breaking the energy-bandwidth limit of electro-optic modulators: theory and a device proposal

    CERN Document Server

    Lin, Hongtao; Liu, Jifeng; Zhang, Lin; Michel, Jurgen; Hu, Juejun

    2013-01-01

    In this paper, we quantitatively analyzed the trade-off between energy per bit for switching and modulation bandwidth of classical electro-optic modulators. A formally simple energy-bandwidth limit (Eq. 10) is derived for electro-optic modulators based on intra-cavity index modulation. To overcome this limit, we propose a dual cavity modulator device which uses a coupling modulation scheme operating at high bandwidth (> 200 GHz) not limited by cavity photon lifetime and simultaneously features an ultra-low switching energy of 0.26 aJ, representing over three orders of magnitude energy consumption reduction compared to state-of-the-art electro-optic modulators.

  11. 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.

  12. A Low Cross-Polarization Smooth-Walled Horn with Improved Bandwidth

    Science.gov (United States)

    Zeng, Lingzhen; Bennette, Charles L.; Chuss, David T.; Wollack, Edward J.

    2009-01-01

    Corrugated feed horns offer excellent beam symmetry, main beam efficiency, and cross-polar response over wide bandwidths, but can be challenging to fabricate. An easier-to-manufacture smooth-walled feed is explored that approximates these properties over a finite bandwidth. The design, optimization and measurement of a monotonically-profiled, smooth-walled scalar feedhorn with a diffraction-limited approx. 14deg FWHM beam is presented. The feed was demonstrated to have low cross polarization (<-30 dB) across the frequency range 33-45 GHz (30% fractional bandwidth). A power reflection below -28 dB was measured across the band.

  13. Experiences with a matrix bandwidth reduction method applied to a finite element problem

    International Nuclear Information System (INIS)

    Large sparsely populated matrices of diagonal character are common in finite element calculations. Computer time is saved and exactness improved if the matrix bandwidth is small. Therefore it is useful to apply a bandwidth reduction procedure to finite element programs, which renumbers the nodal points with the goal of minimum differences between neighboured node numbers. A bandwidth reduction algorithm created by Collins was tested. Some improvements were implemented and its applicability extended to large elements, with 8 nodes instead of 4. A test run dealt with a real technical structural problem and exhibited an excellent efficiency. It recommended to use this procedure as a prerunner to all kinds of finite element programs. (orig.)

  14. Broad-Bandwidth FPGA-Based Digital Polyphase Spectrometer

    Science.gov (United States)

    Jamot, Robert F.; Monroe, Ryan M.

    2012-01-01

    With present concern for ecological sustainability ever increasing, it is desirable to model the composition of Earth s upper atmosphere accurately with regards to certain helpful and harmful chemicals, such as greenhouse gases and ozone. The microwave limb sounder (MLS) is an instrument designed to map the global day-to-day concentrations of key atmospheric constituents continuously. One important component in MLS is the spectrometer, which processes the raw data provided by the receivers into frequency-domain information that cannot only be transmitted more efficiently, but also processed directly once received. The present-generation spectrometer is fully analog. The goal is to include a fully digital spectrometer in the next-generation sensor. In a digital spectrometer, incoming analog data must be converted into a digital format, processed through a Fourier transform, and finally accumulated to reduce the impact of input noise. While the final design will be placed on an application specific integrated circuit (ASIC), the building of these chips is prohibitively expensive. To that end, this design was constructed on a field-programmable gate array (FPGA). A family of state-of-the-art digital Fourier transform spectrometers has been developed, with a combination of high bandwidth and fine resolution. Analog signals consisting of radiation emitted by constituents in planetary atmospheres or galactic sources are downconverted and subsequently digitized by a pair of interleaved analog-to-digital converters (ADCs). This 6-Gsps (gigasample per second) digital representation of the analog signal is then processed through an FPGA-based streaming fast Fourier transform (FFT). Digital spectrometers have many advantages over previously used analog spectrometers, especially in terms of accuracy and resolution, both of which are particularly important for the type of scientific questions to be addressed with next-generation radiometers.

  15. Experimental Demonstration of a Bandwidth Scalable LAN Emulation over EPON Employing OFDMA

    DEFF Research Database (Denmark)

    Deng, Lei; Zhao, Ying

    2011-01-01

    We propose a novel EPON system supporting bandwidth scalable local area network emulation by using orthogonal frequency division multiplexing access technology. Added to the EPON traffic, 250Mbps and 500Mbps OFDM LAN traffics are experimentally emulated.

  16. Expanding the Bandwidth of Slow and Fast Pulse Propagation in Coupled Micro-resonators

    Science.gov (United States)

    Smith, David D.; Chang, Hongrok

    2007-01-01

    Coupled resonators exhibit coherence effects which can be exploited for the delay or advancement of pulses with minimal distortion. The bandwidth and normalized pulse delay are simultaneously enhanced by proper choice of the inter-resonator couplings.

  17. Multi-Hop Bandwidth Management Protocol for Mobile Ad Hoc Networks

    CERN Document Server

    Pattanayak, Binod Kumar; Jagadev, Alok Kumar; Nayak, Manojranjan

    2010-01-01

    An admission control scheme should play the role of a coordinator for flows in a data communication network, to provide the guarantees as the medium is shared. The nodes of a wired network can monitor the medium to know the available bandwidth at any point of time. But, in wireless ad hoc networks, a node must consume the bandwidth of neighboring nodes, during a communication. Hence, the consumption of bandwidth by a flow and the availability of resources to any wireless node strictly depend upon the neighboring nodes within its transmission range. We present a scalable and efficient admission control scheme, Multi-hop Bandwidth Management Protocol (MBMP), to support the QoS requirements in multi-hop ad hoc networks. We simulate several options to design MBMP and compare the performances of these options through mathematical analysis and simulation results, and compare its effectiveness with the existing admission control schemes through extensive simulations. KEYWORDS

  18. Continuous-wave non-classical light with GHz squeezing bandwidth

    CERN Document Server

    Ast, Stefan; Mehmet, Moritz; Steinlechner, Sebastian; Eberle, Tobias; Schnabel, Roman

    2012-01-01

    Squeezed states can be employed for entanglement-based continuous-variable quantum key distribution, where the secure key rate is proportional to the bandwidth of the squeezing. We produced a non-classical continuous-wave laser field at the telecommunication wavelength of 1550 nm, which showed squeezing over a bandwidth of more than 2 GHz. The experimental setup used parametric down-conversion via a periodically poled potassium titanyl phosphate crystal (PPKTP). We did not use any resonant enhancement for the funda- mental wavelength, which should in principle allow a production of squeezed light over the full phase-matching bandwidth of several nanometers. We measured the squeezing to be up to 0.3 dB below the vacuum noise from 50 MHz to 2 GHz limited by the measuring bandwidth of the homodyne detector. The squeezing strength was possibly limited by thermal lensing inside the non-linear crystal.

  19. Analysis of blocking probability for OFDM-based variable bandwidth optical network

    Science.gov (United States)

    Gong, Lei; Zhang, Jie; Zhao, Yongli; Lin, Xuefeng; Wu, Yuyao; Gu, Wanyi

    2011-12-01

    Orthogonal Frequency Division Multiplexing (OFDM) has recently been proposed as a modulation technique. For optical networks, because of its good spectral efficiency, flexibility, and tolerance to impairments, optical OFDM is much more flexible compared to traditional WDM systems, enabling elastic bandwidth transmissions, and optical networking is the future trend of development. In OFDM-based optical network the research of blocking rate has very important significance for network assessment. Current research for WDM network is basically based on a fixed bandwidth, in order to accommodate the future business and the fast-changing development of optical network, our study is based on variable bandwidth OFDM-based optical networks. We apply the mathematical analysis and theoretical derivation, based on the existing theory and algorithms, research blocking probability of the variable bandwidth of optical network, and then we will build a model for blocking probability.

  20. Uniform-in-bandwidth consistency for kernel-type estimators of Shannon's entropy

    OpenAIRE

    Bouzebda, Salim; Elhattab, Issam

    2008-01-01

    We establish uniform-in-bandwidth consistency for kernel-type estimators of the differential entropy. We consider two kernel-type estimators of Shannon's entropy. As a consequence, an asymptotic 100% confidence interval of entropy is provided.

  1. High bandwidth data recording systems for pulsed power and laser produced plasma experiments

    Science.gov (United States)

    May, M. J.; Clancy, T.; Fittinghoff, D.; Halvorson, C.; Mills, T.; Nikitin, A.; Perry, T.; Roberson, G. P.; Smith, D.; Teruya, A.; Miller, E. K.; Trainham, C.

    2006-10-01

    We present two high bandwidth data transmission and recording systems for the measurement of transient signals during pulsed power and laser produced plasmas. These systems use fiber optic cables to transmit analog data over long distances to high bandwidth digitizing oscilloscopes. One system is based on the direct modulation of a laser diode and has a bandwidth of 1.5GHz. The other system is based upon a Mach-Zehnder modulator and has a bandwidth of 12GHz, and is limited by the photoreceiver. The signals are recorded on commercial digitizing oscilloscopes that have approximately six effective bits. The transmission systems use many off-the-shelf components from the telecommunications industry and thus have a high reliability and a moderate cost. Investigation of the reduction in optical transmission of the fibers during exposure to high dose radiation will also be discussed.

  2. High bandwidth data recording systems for pulsed power and laser produced plasma experiments

    International Nuclear Information System (INIS)

    We present two high bandwidth data transmission and recording systems for the measurement of transient signals during pulsed power and laser produced plasmas. These systems use fiber optic cables to transmit analog data over long distances to high bandwidth digitizing oscilloscopes. One system is based on the direct modulation of a laser diode and has a bandwidth of 1.5 GHz. The other system is based upon a Mach-Zehnder modulator and has a bandwidth of 12 GHz, and is limited by the photoreceiver. The signals are recorded on commercial digitizing oscilloscopes that have approximately six effective bits. The transmission systems use many off-the-shelf components from the telecommunications industry and thus have a high reliability and a moderate cost. Investigation of the reduction in optical transmission of the fibers during exposure to high dose radiation will also be discussed

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

    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...

  4. THz Tube Waveguides With Low Loss, Low Dispersion, and High Bandwidth

    DEFF Research Database (Denmark)

    Bao, Hualong; Nielsen, Kristian

    2014-01-01

    We propose, model and experimentally characterize a novel class of terahertz hollow-core tube waveguides with high-loss cladding material, resulting in propagation with low loss, low dispersion, and high useful bandwidth.

  5. Finite-Bandwidth Resonances of High-Order Axial Modes (HOAM) in a Gyrotron Cavity

    CERN Document Server

    Sabchevski, Svilen

    2014-01-01

    Finite-bandwidth resonances of high-order axial modes (HOAM) in an open gyrotron cavity are studied numerically using the GYROSIM problem-oriented software package for modelling, simulation and computer-aided design (CAD) of gyrotron tubes.

  6. The Parameters affecting on Raman Gain and Bandwidth for Distributed Multi-Raman Amplifier

    OpenAIRE

    F. A. El-Geldawy; Fathy M. Mustafa; Ashraf A. Khalaf

    2012-01-01

    Due to the benefits of Raman amplifier for Long-Haul UW-WDM Optical Communications Systems, we interest in this paper to investigate the parameters affecting on Raman gain and bandwidth, and also we are analyzed four and eight Raman pumping of special pump power and pumping wavelengths to show the effect of this parameters on gain and bandwidth. The model equations are numerically handled and processed via specially cast software (Matlab). The gain is computed over the spectral optical wavele...

  7. Relative intensity noise transfer of large-bandwidth pump lasers in Raman fiber amplifiers

    OpenAIRE

    Keïta, Kafing; Delaye, Philippe; Frey, Robert; Roosen, Gérald

    2006-01-01

    A theoretical analysis of the Raman amplification in optical fibers and the pump-to-signal relative intensity noise (RIN) transfer has been performed in the spectral domain. An efficient Raman amplification of a monochromatic signal beam by a large-bandwidth pump beam has been demonstrated for a pump bandwidth much smaller than the Raman linewidth. Under the same approximation the pump-to-signal RIN transfer has been calculated in both cases of copropagating and counterpropagating beams in th...

  8. Bandwidths Statistics from the Eigenvalue Moments for Harper-Hofstadter Problem

    OpenAIRE

    Lipan, O.

    1999-01-01

    I propose a method for studying the product of bandwidths for the Harper-Hofstader model. This method requires knowledge of the moments of the midband energies. I conjectured a general formula for these moments. I computed the asymptotic representation for the product of bandwidths in the limit of a weak magnetic flux using Szego's theorem for Hankel matrices. I then give a first approximation for the edge of the butterfly spectrum and discuss its connection with P. Levy's f...

  9. Tuning gain and bandwidth of traveling wave tubes using metamaterial beam-wave interaction structures

    International Nuclear Information System (INIS)

    We employ metamaterial beam-wave interaction structures for tuning the gain and bandwidth of short traveling wave tubes. The interaction structures are made from metal rings of uniform cross section, which are periodically deployed along the length of the traveling wave tube. The aspect ratio of the ring cross sections is adjusted to control both gain and bandwidth. The frequency of operation is controlled by the filling fraction of the ring cross section with respect to the size of the period cell.

  10. Tuning gain and bandwidth of traveling wave tubes using metamaterial beam-wave interaction structures

    OpenAIRE

    Lipton, Robert; Polizzi, Anthony

    2014-01-01

    We employ metamaterial beam-wave interaction structures for tuning the gain and bandwidth of short traveling wave tubes. The interaction structures are made from metal rings of uniform cross section, which are periodically deployed along the length of the traveling wave tube. The aspect ratio of the ring cross sections are adjusted to control both gain and bandwidth. The frequency of operation is controlled by the filling fraction of the ring cross section with respect to th...

  11. Tuning gain and bandwidth of traveling wave tubes using metamaterial beam-wave interaction structures

    CERN Document Server

    Lipton, Robert

    2014-01-01

    We employ metamaterial beam-wave interaction structures for tuning the gain and bandwidth of short traveling wave tubes. The interaction structures are made from metal rings of uniform cross section, which are periodically deployed along the length of the traveling wave tube. The aspect ratio of the ring cross sections are adjusted to control both gain and bandwidth. The frequency of operation is controlled by the filling fraction of the ring cross section with respect to the period.

  12. Energy-bandwidth trade-off in all-optical photonic crystal microcavity switches

    OpenAIRE

    Heuck, Mikkel; Kristensen, Philip Trøst; Mørk, Jesper

    2011-01-01

    The performance of all-optical switches is a compromise between the achievable bandwidth of the switched signal and the energy requirement of the switching operation. In this work we consider a system consisting of a photonic crystal cavity coupled to two input and two output waveguides. As a specific example of a switching application, we investigate the demultiplexing of an optical time division multiplexed signal. To quantify the energy-bandwidth trade-off, we introduce a figure of merit f...

  13. Design and Simulation of Microstrip E-shaped Patch Antenna for Improved Bandwidth and Directive Gain

    OpenAIRE

    Prof. Jaikaran Singh; Prof. Mukesh Tiwari,; Ms. Neha Patel

    2014-01-01

    Despite the many advantages of microstrip patch antennas, they do have some considerable drawbacks. One of the main limitations with patch antennas is their inherently narrowband performance due to its resonant nature. With bandwidth as low as a few percent; broadband applications using conventional patch designs are limited. So for the antenna miniaturization and bandwidth improvement E-shaped microstrip patch antenna used. In this paper, authors cover two aspects of microstrip antenna de...

  14. Gap-Coupling: A Potential Method for Enhancing the Bandwidth of Microstrip Antennas

    OpenAIRE

    Singh, G; Kumar, P.

    2012-01-01

    In this paper, a technical review on gap-coupled microstrip antennas is presented. The gap-coupled microstrip antennas give a large bandwidth as compared to the conventional microstrip antennas. The method of bandwidth enhancement using gap-coupled microstrip antennas has been elaborated. The gap-coupled microstrip antennas also produce two resonances. The dual frequency operation of the gap-coupled microstrip antenna is also described. A research overview of gap-coupled microstrip antennas, ...

  15. From advertising profits to bandwidth prices-A quantitative methodology for negotiating premium peering

    OpenAIRE

    Gyarmati, Laszlo; Laoutaris, Nikolaos; Sdrolias, Kostas; Rodriguez, Pablo; Courcoubetis, Costas

    2014-01-01

    We have developed a first of its kind methodology for deriving bandwidth prices for premium direct peering between Access ISPs (A-ISPs) and Content and Service Providers (CSPs) that want to deliver content and services in premium quality. Our methodology establishes a direct link between service profitability, e.g., from advertising, user- and subscriber-loyalty, interconnection costs, and finally bandwidth price for peering. Unlike existing work in both the networking and e...

  16. What frequency bandwidth to run cellular network in a given country? - a downlink dimensioning problem

    OpenAIRE

    Blaszczyszyn, Bartlomiej; Karray, Mohamed Kadhem

    2014-01-01

    We propose an analytic approach to the frequency bandwidth dimensioning problem, faced by cellular network operators who deploy/upgrade their networks in various geographical regions (countries) with an inhomogeneous urbanization. We present a model allowing one to capture fundamental relations between users' quality of service parameters (mean downlink throughput), traffic demand, the density of base station deployment, and the available frequency bandwidth. These relations...

  17. HyperTransport 3 Core: A Next Generation Host Interface with Extremely High Bandwidth

    OpenAIRE

    Kalisch, Benjamin; Giese, Alexander; Litz, Heiner; Brüning, Ulrich

    2009-01-01

    As the amount of computing power keeps increasing, host interface bandwidth to memory and input-output devices (I/O) becomes a more and more limiting factor. High speed serial host interface protocols like PCI-Express and HyperTransport (HT) have been introduced to satisfy the applications’ ever increasing demands for more bandwidth. Recent applications in the field of General Purpose Graphic Processing Units (GPGPUs) and Field Programmable Gate Array (FPGA) based coprocessors are an exampl...

  18. Bandwidth comparison of photonic crystal fibers and conventional single-mode fibers

    CERN Document Server

    Nielsen, M D; Mortensen, N A; Bjarklev, A

    2004-01-01

    We experimentally compare the optical bandwidth of a conventional single-mode fiber (SMF) with 3 different photonic crystal fibers (PCF) all optimized for visible applications. The spectral attenuation, single-turn bend loss, and mode-field diameters (MFD) are measured and the PCF is found to have a significantly larger bandwidth than the SMF for an identical MFD. It is shown how this advantage can be utilized for realizing a larger MFD for the PCF while maintaining a bending resistant fiber.

  19. The influence of complex material coverings on the bandwidth of antennas

    CERN Document Server

    Tretyakov, S A; Sochava, A A; Simovski, C R

    2004-01-01

    The influence of material coverings on the antenna bandwidth is investigated for antennas formed by thin electric or magnetic line sources. It is shown that uniform thin layers of arbitrary passive materials (including Veselago, left-handed, or double-negative materials) cannot help to overcome the bandwidth limitations imposed by the amount of energy stored in the antenna reactive field. Alternative possibilities offered by complex composite materials in the antenna design are identified.

  20. Transmit Signal and Bandwidth Optimization in Multiple-Antenna Relay Channels

    OpenAIRE

    Ng, Chris T. K.; Foschini, Gerard J.

    2010-01-01

    Transmit signal and bandwidth optimization is considered in multiple-antenna relay channels. Assuming all terminals have channel state information, the cut-set capacity upper bound and decode-and-forward rate under full-duplex relaying are evaluated by formulating them as convex optimization problems. For half-duplex relays, bandwidth allocation and transmit signals are optimized jointly. Moreover, achievable rates based on the compress-and-forward transmission strategy are ...

  1. High-Density, High-Bandwidth, Multilevel Holographic Memory

    Science.gov (United States)

    Chao, Tien-Hsin

    2008-01-01

    A proposed holographic memory system would be capable of storing data at unprecedentedly high density, and its data transfer performance in both reading and writing would be characterized by exceptionally high bandwidth. The capabilities of the proposed system would greatly exceed even those of a state-of-the art memory system, based on binary holograms (in which each pixel value represents 0 or 1), that can hold .1 terabyte of data and can support a reading or writing rate as high as 1 Gb/s. The storage capacity of the state-of-theart system cannot be increased without also increasing the volume and mass of the system. However, in principle, the storage capacity could be increased greatly, without significantly increasing the volume and mass, if multilevel holograms were used instead of binary holograms. For example, a 3-bit (8-level) hologram could store 8 terabytes, or an 8-bit (256-level) hologram could store 256 terabytes, in a system having little or no more size and mass than does the state-of-the-art 1-terabyte binary holographic memory. The proposed system would utilize multilevel holograms. The system would include lasers, imaging lenses and other beam-forming optics, a block photorefractive crystal wherein the holograms would be formed, and two multilevel spatial light modulators in the form of commercially available deformable-mirror-device spatial light modulators (DMDSLMs) made for use in high speed input conversion of data up to 12 bits. For readout, the system would also include two arrays of complementary metal oxide/semiconductor (CMOS) photodetectors matching the spatial light modulators. The system would further include a reference-beam sterring device (equivalent of a scanning mirror), containing no sliding parts, that could be either a liquid-crystal phased-array device or a microscopic mirror actuated by a high-speed microelectromechanical system. Time-multiplexing and the multilevel nature of the DMDSLM would be exploited to enable writing and reading of multilevel holograms. The DMDSLM would also enable transfer of data at a rate of 7.6 Gb/s or perhaps somewhat higher.

  2. Design of bandwidth tunable HTS filter using H-shaped waveguides

    International Nuclear Information System (INIS)

    We have developed a bandwidth tuning method for use in high-temperature superconducting (HTS) microstrip filters. Several H-shaped waveguides are placed between the resonators, and the bandwidth is adjusted by changing the switch states of the waveguides. The coupling coefficients between the resonators are controlled by switching the connection or isolation of the center gaps of the waveguides so as to tune the bandwidth. The effects of using this method were evaluated by simulation using a filter composed of 3-pole half-wavelength straight-line resonators with an H-shaped waveguide between each pair and additional electric pads for post-tuning trimming. The filter was designed to have a center frequency of 5 GHz and a bandwidth of 100 MHz by using an electromagnetic simulator based on the moment method. The simulation showed that bandwidth tuning of 150 MHz can be obtained by using H-shaped waveguides to adjust the coupling coefficients. It also showed that using additional electric pads around the feed lines, which was previously shown to be useful for trimming to improve insertion loss after center-frequency tuning, is also useful for bandwidth tuning.

  3. On Bandwidth Characteristics of Tuning Fork Micro-Gyroscope with Mechanically Coupled Sense Mode

    Directory of Open Access Journals (Sweden)

    Yunfang Ni

    2014-07-01

    Full Text Available The bandwidth characteristics of a tuning fork micro-gyroscope with mechanically coupled sense mode were investigated in this paper to provide some references for mechanical bandwidth design. The concept of sense mode mechanical coupling is introduced first. Theoretical frequency response analyses were then carried out on the mechanical part of the gyroscope. Equations representing the relationships between the differential output signal and the frequency of the input angular rate were deduced in full frequency range and further simplified in low frequency range. Based on these equations, bandwidth characteristics under ideal and non-ideal conditions are discussed. Analytical results show that under ideal conditions, the bandwidth characteristics of a tuning fork micro-gyroscope are similar to those of a single mass micro-gyroscope, but under non-ideal conditions, especially when sense mass and/or stiffness are asymmetric, the bandwidth characteristics would be quite different because the in-phase mode would participate in the anti-phase vibration response. Experimental verifications were carried out on two micro-gyroscope prototypes designed in our laboratory. The deduced equations and analytical results can be used in guiding the mechanical bandwidth design of tuning fork micro-gyroscopes with mechanically coupled sense mode.

  4. An impact excitation system for repeatable, high-bandwidth modal testing of miniature structures

    Science.gov (United States)

    Bediz, Bekir; Korkmaz, Emrullah; Burak Ozdoganlar, O.

    2014-06-01

    Miniature components and devices are increasingly seen in a myriad of applications. In general, the dynamic behavior of miniature devices is critical to their functionality and performance. However, modal testing of miniature structures poses many challenges. This paper presents a design and evaluation of an impact excitation system (IES) for repeatable, high-bandwidth, controlled-force modal testing of miniature structures. Furthermore, a dynamic model of the system is derived and experimentally validated to enable the identification of the system parameters that yield single-hit impacts with desired bandwidth and force magnitude. The system includes a small instrumented impact tip attached to a custom designed flexure-based body, an automated electromagnetic release mechanism, and various precision positioners. The excitation bandwidth and the impact force magnitude can be controlled by selecting the system parameters. The dynamic model of the system includes the structural dynamics of the flexure-based body, the electromagnetic force and the associated eddy-current damping, and the impact event. A validation study showed an excellent match between the model simulations and experiments in terms of impact force and bandwidth. The model is then used to create process maps that relate the system parameters to the number of hits (single vs. multiple), the impact force magnitudes and the excitation bandwidths. These process maps can be used to select system parameters or predict system response for a given set of parameters. A set of experiments is conducted to compare the performances of the IES and a (manual) miniature impact hammer. It is concluded that the IES significantly improves repeatability in terms of the impact bandwidth, location, and force magnitude, while providing a high excitation-bandwidth and excellent coherence values. The application of the IES is demonstrated through modal testing of a miniature contact-probe system.

  5. 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 (??/?˜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 (??˜1THz) to observations for narrower bandwidth operation (??˜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.

  6. Maximum Bandwidth Enhancement of Current Mirror using Series-Resistor and Dynamic Body Bias Technique

    Directory of Open Access Journals (Sweden)

    V. Niranjan

    2014-09-01

    Full Text Available This paper introduces a new approach for enhancing the bandwidth of a low voltage CMOS current mirror. The proposed approach is based on utilizing body effect in a MOS transistor by connecting its gate and bulk terminals together for signal input. This results in boosting the effective transconductance of MOS transistor along with reduction of the threshold voltage. The proposed approach does not affect the DC gain of the current mirror. We demonstrate that the proposed approach features compatibility with widely used series-resistor technique for enhancing the current mirror bandwidth and both techniques have been employed simultaneously for maximum bandwidth enhancement. An important consequence of using both techniques simultaneously is the reduction of the series-resistor value for achieving the same bandwidth. This reduction in value is very attractive because a smaller resistor results in smaller chip area and less noise. PSpice simulation results using 180 nm CMOS technology from TSMC are included to prove the unique results. The proposed current mirror operates at 1Volt consuming only 102 µW and maximum bandwidth extension ratio of 1.85 has been obtained using the proposed approach. Simulation results are in good agreement with analytical predictions.

  7. ENHANCEMENT OF BANDWIDTH OF RECTANGULAR PATCH ANTENNA USING TWO SQUARE SLOTS TECHNIQUES

    Directory of Open Access Journals (Sweden)

    Patil V. P.

    2012-10-01

    Full Text Available The research in wireless communication has spurred the development of extra ordinary range of antennas, each with its own advantage and limitations. There are many applications where space is at premium, and where there is an urgent need for an antenna with the flexibility to efficiently combine the capabilities of multiple antennas. In fact rapidly developing market in personal communication systems (PCS, mobile satellite communications, direct broadband television (DBS wireless local area networks (WLANs suggest that demand for Microstrip antennas and array will increase even further. Conventional Microstrip patch antennas has some drawbacks of low efficiency, narrow bandwidth (3-6% of the central frequency, its bandwidth is limited to a few percent which is not enough for most of the wireless communication systems nowadays. In this paper one of the efficient methods used for the enhancement of patch antenna bandwidth is the loading of rectangular microstrip patch antenna with two square slots across its side surface. This type of Microstrip patch antenna meets the requirement of operation for wireless applications. The proposed configuration is simulated and analyzed using GENESYS software package. The VSWR, input impedance‚ and S11 performance are used for the analysis of the different configurations. The simulated results for square slots antenna structure give bandwidth of 311 MHZ. Feed point on the patch that gives a good match of 50 ohm. The results of the fabricated microstrip antenna give the bandwidth of 286 MHz.

  8. High-bandwidth quantum memory protocol for storing single photons in rare-earth doped crystals

    International Nuclear Information System (INIS)

    We present a detailed analysis of a high-bandwidth quantum memory protocol for storing single photons in a rare-earth-ion doped crystal. The basic idea is to benefit from a coherent free-induced decay type re-emission which occurs naturally when a photon with a broadband spectrum is absorbed by a narrow atomic transition in an optically dense ensemble. This allows for a high-bandwidth memory for realistic material parameters. Long storage time and on-demand readout are obtained by means of spin states in a lambda-type configuration, through the transfer of the optical coherence to a spin coherence (so-called spin-wave storage). We give explicit formulae and show numerical results which make it possible to gain insight into the dependence of the memory efficiency on the optical depth and on the width and the shape of stored photons. We present a feasibility study in rare-earth doped crystals and show that high efficiencies and high bandwidth can be obtained with realistic parameters. High-bandwidth memories using spin-wave storage offers the possibility of very high time-bandwidth products, which is important for experiments where high repetition rates are needed. (paper)

  9. MULTI-PATH MECHANISM FOR BROADCASTING AUDIO / VIDEO STREAMING BASED ON BANDWIDTH ESTIMATION

    Directory of Open Access Journals (Sweden)

    Ashish Parejiya

    2015-05-01

    Full Text Available By the significant development of network routine which entail of Internet and the transmission of high-end terminals such as smart-phones, laptops, Ipod or any media receiver, media broadcasting streaming service is fetching one of the major communication technologies. However current packet networks still cannot provide a stable transmission quality and it can cause stream quality deprivation. Especially, the main factor affecting quality is congestion across a network. Well-organized utilization of available bandwidth over multiple access networks of multi-homed devices can be a reasonable solution to provide good quality for real-time media streaming applications. In this paper, we propose Real Time & Multi-path Transmission Protocol (RTMTP, a transport layer protocol in which multiple path real-time transport is available. Our protocol exploits RTP’s real-time features and SCTP’s multi-homing capability by enabling the use of multiple paths to transfer media streams. RTMTP uses the end-to-end sender-based bandwidth estimation mechanism to measure the actual available bandwidth of each path. To exploit network bandwidth productivity of multiple paths, the RTMTP shares traffic among those paths and the transmission rate for each path is determined allowing to the measured available bandwidth. RTMTP also helps users to use their preferred access network as much as possible. Our simulation results show that RTMTP improves streaming broadcast output.

  10. Design and fabrication of center frequency and bandwidth tunable HTS filter

    International Nuclear Information System (INIS)

    Highlights: ? We have developed a bandwidth and a center frequency tunable HTS filter. ? A tunable passband ratio of 1.8:1 was achieved. ? An 8% of center frequency tuning at 5 GHz was achieved. ? Adjustment of external quality factors improves the filter response after tuning. -- Abstract: We have developed a bandwidth and a center frequency tuning method for use in high-temperature superconducting microstrip filters. A pair of waveguide is placed between the resonators, and the bandwidth is adjusted by changing the switch states of the waveguides. Additional electrical pads are placed open ends of the resonators for tuning the center frequency. Pads are also placed around the input/output coupled-line elements to enable the external quality factors to be adjusted, thereby reducing the insertion loss caused by tuning. A prototype three-pole tunable bandpass filter was fabricated by depositing YBa2Cu3O7 thin film on an MgO substrate and has a measured center frequency of 4.83 GHz and bandwidth of 121 MHz. Use of the waveguides to adjust the coupling coefficients, the electrical pads to adjust the effective lengths of the resonators and the pads to adjust the external quality factors resulted in 120-MHz bandwidth tuning and 400-MHz center frequency tuning without increased insertion loss

  11. Percentage Based Trust Model with Bandwidth Reservation Technique for Privacy Preserving Routing in MANETs

    Directory of Open Access Journals (Sweden)

    Raghu. R , Gopinathan. B

    2013-02-01

    Full Text Available Routing in Mobile Ad-Hoc Networks are vulnerable to malicious traffic analysis, harmful attackers can mitigate paths and malicious intermediate nodes breaks security, ineffective reserve of available resources ( utilization of bandwidth in node causes losses and as well as anonymity, unobservability of communication is not provided. To detect misbehaviors and effective utilization of resources in trusted nodes the Percentage Based Trust management system, with bandwidth reservation technique is proposed, and for achieving privacy in MANETs the PPRP is proposed. In this paper the scheme called Percentage based Trust management system is defined to allow trustworthy intermediate nodes to participate in path construction with resource reservation technique to allow trusted nodes to select a path which has minimum cost, congestion and bandwidth. In reservation technique, if available bandwidth is greater than traffic jam bandwidth. Using rate monitoring and adjustment methodologies, rate control is performed for the overcrowded flows and then an Privacy Preserving routing Protocol (PPRP is proposed to offer complete anonymity, unlinkability and unobservabilty for all types of packets. PPRP uses novel combination of group signature and Id based encryption techniques for route discovery. The simulation result shows that this paper achieves trustworthy path construction through intermediate nodes with resource allocation technique and stronger privacy protection is achieved than existing scheme like AODV.

  12. Movie approximation technique for the implementation of fast bandwidth-smoothing algorithms

    Science.gov (United States)

    Feng, Wu-chi; Lam, Chi C.; Liu, Ming

    1997-12-01

    Bandwidth smoothing algorithms can effectively reduce the network resource requirements for the delivery of compressed video streams. For stored video, a large number of bandwidth smoothing algorithms have been introduced that are optimal under certain constraints but require access to all the frame size data in order to achieve their optimal properties. This constraint, however, can be both resource and computationally expensive, especially for moderately priced set-top-boxes. In this paper, we introduce a movie approximation technique for the representation of the frame sizes of a video, reducing the complexity of the bandwidth smoothing algorithms and the amount of frame data that must be transmitted prior to the start of playback. Our results show that the proposed approximation technique can accurately approximate the frame data with a small number of piece-wise linear segments without affecting the performance measures that the bandwidth soothing algorithms are attempting to achieve by more than 1%. In addition, we show that implementations of this technique can speed up execution times by 100 to 400 times, allowing the bandwidth plan calculation times to be reduced to tens of milliseconds. Evaluation using a compressed full-length motion-JPEG video is provided.

  13. Optimization of Inter-network Bandwidth Resources for Large-Scale Data Transmission

    Directory of Open Access Journals (Sweden)

    Mu Zhang

    2014-03-01

    Full Text Available In order to solve problems such as low resources utilization of data center backbone bandwidth and expensive daily expenses caused by the tidal effect in the transition of large-scale network data, the new optimization method of bandwidth resource for bulk data transfer is proposed. This method finishes the bulk data transfer by taking full advantage of the idle channel bandwidth. Firstly, the dynamic idle network bandwidth resource was switched into the static flow network; and then the max-min fair multi-commodity flow model is built on the basis of static network; finally, the iterative technique is used to solve the programming model for getting the maximum transport flows and the corresponding transmission path of bulk data transfer. The simulation method was used to test this optimization project. The results show that the optimization method proposed by the paper can significantly improve the utilization of data center backbone bandwidth resource, and the maximum amount of data transmission and the speed of data transfer have been obviously increased

  14. Analysis of Design Optimization of Bandwidth and Loss Performance of Reflectarray Antennas Based on Material Properties

    Directory of Open Access Journals (Sweden)

    Muhammad Yusof Ismail

    2009-12-01

    Full Text Available An investigation for the enhancement strategy of bandwidth performance and analysis of different types of losses associated with reflectarray antennas is presented in this paper. Studies are carried out using different commercially available dielectric materials with dielectric permittivity (?r values ranging from 2.08 to 13 and loss tangent (tan? ranging from 0.0003 to 0.025. The performance of different dielectric materials for the design of infinite reflectarray is analyzed in terms of bandwidth, reflection loss and Figure of Merit (FOM. Bandwidths at different levels are observed and it has been noticed that 10% bandwidth varies from 84 MHz to 360MHz and 20% bandwidth varies from 126 MHz to 540MHz based on the selection of dielectric substrate for reflectarray antenna design. Moreover it has been demonstrated that the reflection loss of the reflectarray antenna can be factorized into dielectric loss and conductor loss which depends on the material properties used for the design. Detailed numerical analysis is carried out in order to verify the acquired results.

  15. An efficient Bandwidth Demand Estimation for Delay Reduction in IEEE 802.16j MMR WiMAX Networks

    Directory of Open Access Journals (Sweden)

    Fath Elrahman Ismael

    2010-01-01

    Full Text Available IEEE 802.16j MMR WiMAX networks allow the number of hops between the user andthe MMR-BS to be more than two hops. The standard bandwidth request procedure inWiMAX network introduces much delay to the user data and acknowledgement of theTCP packet that affects the performance and throughput of the network. In this paper,we propose a new scheduling scheme to reduce the bandwidth request delay in MMRnetworks. In this scheme, the MMR-BS allocates bandwidth to its direct subordinate RSswithout bandwidth request using Grey prediction algorithm to estimate the requiredbandwidth of each of its subordinate RS. Using this architecture, the access RS canallocate its subordinate MSs the required bandwidth without notification to the MMR-BS.Our scheduling architecture with efficient bandwidth demand estimation able to reducedelay significantly.

  16. Improving QoS Of WiMAX By On_Demand Bandwidth Allocation Based On PMP Mode

    OpenAIRE

    ZhenTao Sun; Abdullah Gani; XiuYing Sun; Ning Liu

    2011-01-01

    Abstract—The bandwidth allocation in both wired and wireless networks has posed great challenges to network engineers for improving desirable Quality of Service (QoS), Bandwidth allocation is always an important element for improve QoS of network. Despite this, IEEE 802.16e-2005 does not have a bandwidth allocation algorithm or mechanism to support (worldwide interoperability for microwave access) WiMAX network presently. This includes both uplink (UL) and downlink (DL) directions. Thus...

  17. Power-Bandwidth Tradeoff in Dense Multi-Antenna Relay Networks

    CERN Document Server

    Oyman, Ozgur

    2007-01-01

    We consider a dense fading multi-user network with multiple active multi-antenna source-destination pair terminals communicating simultaneously through a large common set of $K$ multi-antenna relay terminals in the full spatial multiplexing mode. We use Shannon-theoretic tools to analyze the tradeoff between energy efficiency and spectral efficiency (known as the power- bandwidth tradeoff) in meaningful asymptotic regimes of signal-to-noise ratio (SNR) and network size. We design linear distributed multi-antenna relay beamforming (LDMRB) schemes that exploit the spatial signature of multi-user interference and characterize their power-bandwidth tradeoff under a system wide power constraint on source and relay transmissions. The impact of multiple users, multiple relays and multiple antennas on the key performance measures of the high and low SNR regimes is investigated in order to shed new light on the possible reduction in power and bandwidth requirements through the usage of such practical relay cooperation...

  18. Bandwidth and resolution of super-resolution imaging with perforated solids

    Directory of Open Access Journals (Sweden)

    Zixian Liang

    2011-12-01

    Full Text Available Recent experiments on acoustic superlens and hyperlens found anisotropic metamaterials constructed from periodic perforated solids can be used for super-resolution imaging. Here, we present a theoretical study on the operational bandwidth of these imaging devices using the emerging framework of transformation acoustics. Within the transformation approach, both the microstructural superlens and hyperlens can be discussed using the transfer matrix method on the same footing. We show that the geometrical structure of the periodic metamaterials induces that an acoustics hyperlens has a very wide operational frequency bandwidth with its subwavelength resolution limited by the ratio of image magnification while an acoustics superlens has a very deep subwavelength resolution limited only by the periodicity of the perforations but intrinsically working at a narrow frequency bandwidth. Such investigation will become useful for designing future transformation acoustical imaging devices.

  19. A Distributed Cluster Scheme For Bandwidth Management In Multi-hop MANETs

    CERN Document Server

    Pattanayak, Binod Kumar; Mishra, Manoj Kumar; Nayak, Manoj Ranjan

    2010-01-01

    Electronic collaboration among devices in a geographically localized environment is made possible with the implementation of IEEE 802.11 based wireless ad hoc networks. Dynamic nature of mobile ad hoc networks(MANETs) may lead to unpredictable intervention of attacks or fault occurrence, which consequently may partition the network, degrade its performance, violate the QoS requirements and most importantly, affect bandwidth allocation to mobile nodes in the network. In this paper, we propose a new distributed cluster scheme for MANETs, especially in harsh environments, based on the concept of survivability to support QoS requirements and to protect bandwidth efficiently. With the incorporation of clustering algorithms in survivability technology, we employ a simple network configuration and expect to reduce occurrences of faults in MANETs. At the same time, we address the scalability problem, which represents a great challenge to network configuration. We do expect a simplification of accessing bandwidth allo...

  20. On Artificial Magneto-Dielectric Loading for Improving the Impedance Bandwidth Properties of Microstrip Antennas

    CERN Document Server

    Ikonen, P; Simovski, C; Tretyakov, S A; Ikonen, Pekka; Maslovski, Stanislav; Simovski, Constantin; Tretyakov, Sergei

    2005-01-01

    In the present paper we discuss the effect of artificial magneto-dielectric substrates on the impedance bandwidth properties of microstrip antennas. The results found in the literature for antenna miniaturization using magnetic or magneto-dielectric substrates are revised, and discussion is addressed to the practically realizable artificial magnetic media operating in the microwave regime. Using a transmission-line model we, first, reproduce the known results for antenna miniaturization with non-dispersive material fillings. Next, a realistic dispersive behavior of a practically realizable artificial substrate is embedded into the model, and we show that frequency dispersion of the substrate plays a very important role in the impedance bandwidth characteristics of the loaded antenna. The impedance bandwidths of reduced size patch antennas loaded with dispersive magneto-dielectric substrates and high-permittivity substrates are compared. It is shown that unlike substrates with dispersion-free permeability, pra...

  1. Design and Simulation of Microstrip E-shaped Patch Antenna for Improved Bandwidth and Directive Gain

    Directory of Open Access Journals (Sweden)

    Prof. Jaikaran Singh

    2014-03-01

    Full Text Available Despite the many advantages of microstrip patch antennas, they do have some considerable drawbacks. One of the main limitations with patch antennas is their inherently narrowband performance due to its resonant nature. With bandwidth as low as a few percent; broadband applications using conventional patch designs are limited. So for the antenna miniaturization and bandwidth improvement E-shaped microstrip patch antenna used. In this paper, authors cover two aspects of microstrip antenna designs. The first is the analysis of single element narrowband rectangular microstrip antenna which operates at the central frequency of 6.5GHz. The second aspect is the analysis and design of slot cut E-shaped microstrip antenna. The simulation process has been done through high frequency structure simulator (HFSS. The properties of antenna such as bandwidth, return loss, VSWR has been investigated and compared between a single element rectangular and E-shaped microstrip antenna.

  2. Local intelligent electronic device (IED) rendering templates over limited bandwidth communication link to manage remote IED

    Science.gov (United States)

    Bradetich, Ryan; Dearien, Jason A; Grussling, Barry Jakob; Remaley, Gavin

    2013-11-05

    The present disclosure provides systems and methods for remote device management. According to various embodiments, a local intelligent electronic device (IED) may be in communication with a remote IED via a limited bandwidth communication link, such as a serial link. The limited bandwidth communication link may not support traditional remote management interfaces. According to one embodiment, a local IED may present an operator with a management interface for a remote IED by rendering locally stored templates. The local IED may render the locally stored templates using sparse data obtained from the remote IED. According to various embodiments, the management interface may be a web client interface and/or an HTML interface. The bandwidth required to present a remote management interface may be significantly reduced by rendering locally stored templates rather than requesting an entire management interface from the remote IED. According to various embodiments, an IED may comprise an encryption transceiver.

  3. Narrow Bandwidth 850-nm Fiber Bragg Gratings in Few-Mode Polymer Optical Fibers

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, Wu

    2011-01-01

    We report on the inscription and characterization of narrow bandwidth fiber Bragg gratings (FBGs) with 850-nm resonance wavelength in polymer optical fibers (POFs). We use two fibers: an in-house fabricated microstructured POF (mPOF) with relative hole size of 0.5 and a commercial step-index POF, which supports six modes at 850 nm. The gratings have been written with the phase-mask technique and a 325-nm HeCd laser. The mPOF grating has a full-width at half-maximum (FWHM) bandwidth of 0.29 nm and the step-index POF has a bandwidth of 0.17 nm. For both fibers, the static tensile strain sensitivity is measured to be 0.71 pm/$muvarepsilon$ at 850 nm and 1.3 pm/$muvarepsilon$ at 1550 nm.

  4. Modulation bandwidth of a double tunnelling-injection quantum dot laser

    Science.gov (United States)

    Asryan, Levon V.

    2015-03-01

    The modulation response of a double tunnelling-injection (DTI) quantum dot (QD) laser is studied. Closed-form expressions are obtained for the dynamic characteristics of the laser and the upper limit for the modulation bandwidth is estimated. The optimum cavity length, surface density of QDs, and dc injection current density, maximizing the modulation bandwidth, are shown to exist. The higher the dc injection current density, the smaller should be the optimum values of the cavity length and the surface density of QDs. While the maximum bandwidth is shown to be the same in DTI and conventional QD lasers and unaffected by the differential gain, the optimum dc current density, being inversely proportional to the differential gain, is lower in a DTI laser.

  5. Optical Sideband Generation: a Longitudinal Electron Beam Diagnostic Beyond the Laser Bandwidth Resolution Limit

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Berkeley National Laboratory; Tilborg, J. van; Matlis, N. H.; Plateau, G. R.; Leemans, W. P.

    2010-06-01

    Electro-optic sampling (EOS) is widely used as a technique to measure THz-domain electric field pulses such asthe self-fields of femtosecond electron beams. We present an EOS-based approach for single-shot spectral measurement that excels in simplicity (compatible with fiber integration) and bandwidth coverage (overcomes the laser bandwidth limitation), allowing few-fs electron beams or single-cycle THz pulses to be characterized with conventional picosecond probes. It is shown that the EOS-induced optical sidebands on the narrow-bandwidth optical probe are spectrally-shifted replicas of the THz pulse. An experimental demonstration on a 0-3 THz source is presented.

  6. BECPA : Bandwidth Efficient Cluster Based Packet Aggregation in Wireless Sensor Network

    DEFF Research Database (Denmark)

    Dnyaneshwar, Mantri; Prasad, Neeli R.

    2014-01-01

    In recent years, energy consumption and data gathering is a foremost concern in many applications of wireless sensor networks (WSN). The major issue in WSN is effective utilization of the resource as energy and bandwidth with a large gathering of data from the monitoring and control applications. This paper proposes novel bandwidth efficient cluster based packet aggregation algorithm (BECPA) for heterogeneous WSN. It combines the idea of variable packet generation rate of each node with random data. The nodes are randomly distributed with different energy level with equal in numbers. It uses the perfectly compressible aggregation function at cluster head based on the correlation of packets and data generated by nodes. The aggregation functions prevent transmission of redundant packets. Compare to state-of-the-art solutions, the algorithm shows significant energy saving by reducing the number of packets at the sink with better bandwidth utilization in packet aggregation than data aggregation.

  7. Design and Bandwidth Analysis of Fault-Tolerant Multistage Interconnection Networks

    Directory of Open Access Journals (Sweden)

    R. Aggarwal

    2008-01-01

    Full Text Available The design of a suitable interconnection network for inter-processor communication is one of the key issues of the system performance. In this study a new irregular interconnection network IABN (Irregular Augmented Baseline has been proposed. IABN is designed by modifying existing ABN (Augmented Baseline Network. ABN is a regular multi-path network with limited fault tolerance. IABN provides three times more paths between any pair of source-destination in comparison to ABN. The ABN and IABN MINs are analyzed and compared in terms of performance parameters namely Bandwidth, Cost and Bandwidth per unit Cost. The proposed network IABN provides much better fault-tolerance and almost double bandwidth at the expanse of little more cost than ABN.

  8. A high-bandwidth amplitude estimation technique for dynamic mode atomic force microscopy

    International Nuclear Information System (INIS)

    While often overlooked, one of the prerequisites for high-speed amplitude modulation atomic force microscopy is a high-bandwidth amplitude estimation technique. Conventional techniques, such as RMS to DC conversion and the lock-in amplifier, have proven useful, but offer limited measurement bandwidth and are not suitable for high-speed imaging. Several groups have developed techniques, but many of these are either difficult to implement or lack robustness. In this contribution, we briefly outline existing amplitude estimation methods and propose a new high-bandwidth estimation technique, inspired by techniques employed in microwave and RF circuit design, which utilizes phase cancellation to significantly improve the performance of the lock-in amplifier. We conclude with the design and implementation of a custom circuit to experimentally demonstrate the improvements and discuss its application in high-speed and multifrequency atomic force microscopy

  9. 360/degree/ digital phase detector with 100-kHz bandwidth

    International Nuclear Information System (INIS)

    The general availability of digital circuit components with propagation delay times of a few nanoseconds makes a digital phase detector with good bandwidth feasible. Such a circuit has a distinct advantage over its analog counterpart because of its linearity over a wide range of phase shift. A description is given of a phase detector that is being built at Los Alamos National Laboratory for the Fusion Materials Irradiation Test (FMIT) project. The specifications are 100-kHz bandwidth, linearity of /plus or minus/1/degree/ over /plus or minus/180/degree/ of phase shift, and 0.66/degree/ resolution. To date, the circuit has achieved the bandwidth and resolution. The linearity is approximately /plus or minus/3/degree/ over /plus or minus/180/degree/ phase shift. 3 refs

  10. Narrowing the filter-cavity bandwidth in gravitational-wave detectors via optomechanical interaction.

    Science.gov (United States)

    Ma, Yiqiu; Danilishin, Shtefan L; Zhao, Chunnong; Miao, Haixing; Korth, W Zach; Chen, Yanbei; Ward, Robert L; Blair, D G

    2014-10-10

    We propose using optomechanical interaction to narrow the bandwidth of filter cavities for achieving frequency-dependent squeezing in advanced gravitational-wave detectors, inspired by the idea of optomechanically induced transparency. This can allow us to achieve a cavity bandwidth on the order of 100 Hz using small-scale cavities. Additionally, in contrast to a passive Fabry-Pérot cavity, the resulting cavity bandwidth can be dynamically tuned, which is useful for adaptively optimizing the detector sensitivity when switching amongst different operational modes. The experimental challenge for its implementation is a stringent requirement for very low thermal noise of the mechanical oscillator, which would need a superb mechanical quality factor and a very low temperature. We consider one possible setup to relieve this requirement by using optical dilution to enhance the mechanical quality factor. PMID:25375698

  11. Comparison of Available Bandwidth Estimation Techniques in Packet-Switched Mobile Networks

    DEFF Research Database (Denmark)

    López Villa, Dimas; Ubeda Castellanos, Carlos

    2006-01-01

    The relative contribution of the transport network towards the per-user capacity in mobile telecommunication systems is becoming very important due to the ever increasing air-interface data rates. Thus, resource management procedures such as admission, load and handover control can make use of information regarding the available bandwidth in the transport network, as it could end up being the bottleneck rather than the air interface. This paper provides a comparative study of three well known available bandwidth estimation techniques, i.e. TOPP, SLoPS and pathChirp, taking into account the statistical conditions of the available bandwidth and assessing the variability of their estimations. Simulation-based studies on a mobile transport network show that pathChirp outperforms TOPP and SLoPS, both in terms of accuracy and efficiency.

  12. Dynamic Online Bandwidth Adjustment Scheme Based on Kalai-Smorodinsky Bargaining Solution

    Science.gov (United States)

    Kim, Sungwook

    Virtual Private Network (VPN) is a cost effective method to provide integrated multimedia services. Usually heterogeneous multimedia data can be categorized into different types according to the required Quality of Service (QoS). Therefore, VPN should support the prioritization among different services. In order to support multiple types of services with different QoS requirements, efficient bandwidth management algorithms are important issues. In this paper, I employ the Kalai-Smorodinsky Bargaining Solution (KSBS) for the development of an adaptive bandwidth adjustment algorithm. In addition, to effectively manage the bandwidth in VPNs, the proposed control paradigm is realized in a dynamic online approach, which is practical for real network operations. The simulations show that the proposed scheme can significantly improve the system performances.

  13. Electrically driving bandwidth tunable guided-mode resonance filter based on a twisted nematic liquid crystal polarization rotator.

    Science.gov (United States)

    Qian, Linyong; Zhang, Dawei; Dai, Bo; Huang, Yuanshen; Tao, Chunxian; Hong, Ruijin; Zhuang, Songlin

    2015-03-01

    A novel bandwidth-tunable filter is proposed based on nonpolarizing guided-mode resonance effect. The compact, electrically driving bandwidth-tunable optical filter is realized by taking advantage of the effect of bandwidth-to-polarization sensitivity and using a twisted nematic liquid crystal polarization rotator for simple and precise polarization control. The operation principle and the design of the device are presented. The center wavelength is fixed at 623.1 nm with a relatively symmetric line shape. The full-width at half-maximum bandwidth is tuned from 12 to 44.8 nm by controlling the voltage in the polarization rotator. PMID:25723414

  14. Estimating individual listeners’ auditory-filter bandwidth in simultaneous and non-simultaneous masking

    DEFF Research Database (Denmark)

    Buchholz, Jörg; Caminade, Sabine

    2010-01-01

    Frequency selectivity in the human auditory system is often measured using simultaneous masking of tones presented in notched noise. Based on such masking data, the equivalent rectangular bandwidth (ERB) of the auditory filters can be derived by applying the power spectrum model of masking and assuming a rounded-exponential filter shape. If a forward masking paradigm is used instead of simultaneous masking, filter estimates typically show significantly sharper tuning. This difference in frequency selectivity has commonly been related to spectral suppression mechanisms observed in the cochlea. Considering bandwidth estimates from previous studies based on forward masking, only average data across a number of subjects have been considered. The present study is concerned with bandwidth estimates in simultaneous and forward masking in individual normal-hearing subjects. In order to investigate the reliability of the individual estimates, a statistical resampling method is applied. It is demonstrated that a ratherlarge set of experimental data is required to reliably estimate auditory filter bandwidth, particularly in the case of simultaneous masking. The poor overall reliability of the filter estimates was found to be mainly related to the very short tone duration (i.e., 10 ms) that was chosen. Applying 300-ms long tones in simultaneous masking drastically improved the reliability of the filter estimates. The tone duration in forward masking had to be very short to elicit a sufficient amount of masking. Based on extensive data for three subjects, the difference between forward and simultaneous masking es-timates of auditory filter bandwidth was found to be even larger than previously reported, with a bandwidth decrease by a factor of about 1.8 rather than 1.4. The results of the study can be used to optimize the measures of frequency selectivity which is particularly useful when studying consequences of (individual) hearing impairment.

  15. The Parameters affecting on Raman Gain and Bandwidth for Distributed Multi-Raman Amplifier

    Directory of Open Access Journals (Sweden)

    F. A. El-Geldawy

    2012-09-01

    Full Text Available Due to the benefits of Raman amplifier for Long-Haul UW-WDM Optical Communications Systems, we interest in this paper to investigate the parameters affecting on Raman gain and bandwidth, and also we are analyzed four and eight Raman pumping of special pump power and pumping wavelengths to show the effect of this parameters on gain and bandwidth. The model equations are numerically handled and processed via specially cast software (Matlab. The gain is computed over the spectral optical wavelengths (1.45m signal 1.65m.

  16. Confidentiality & Authentication Mechanism for Biometric Information Transmitted over Low Bandwidth & Unreliable channel

    CERN Document Server

    Singh, Raju

    2011-01-01

    The security of bio-metric information - finger print, retina mapping, DNA mapping and some other chemical and biological modified genes related information - transfer through low bandwidth and unreliable or covert channel is challenging task. Therefore, Security of biometric information is essential requirement in this fast developing communication world. Thus, in this paper, we propose efficient and effective mechanism for confidentiality and authentication for biometric information transmitted by using arithmetic encoding representation over low bandwidth and unreliable channel. It enhances the speed of encryption, decryption and authentication process. It uses arithmetic encoding scheme and public key cryptography e.g. modified version of RSA algorithm called RSA-2 algorithm.

  17. Enhanced narrow-bandwidth emission during high-order harmonic generation from aligned molecules.

    Science.gov (United States)

    Zhang, Chaojin; Yao, Jinping; Umran, Fadhil A; Ni, Jielei; Zeng, Bin; Li, Guihua; Lin, Di

    2013-02-11

    We theoretically investigate the selective enhancement of high-harmonic generation (HHG) in a small spectral range when an orthogonal-polarized two-color laser field interacts with aligned O(2) molecules. It is shown clearly that the enhanced narrow-bandwidth emission near the cutoff of the HHG spectrum can be effectively controlled by the molecular alignment angle, laser intensity and the relative phase of two-color laser fields. Furthermore, the strong dependence of narrow-bandwidth HHG on molecular alignment angle indicates that it encodes information about O(2) molecular orbitals, so it may be an alternative method for reconstruction of O(2) molecular orbitals. PMID:23481785

  18. Accurate and efficient simulation of bandwidth dynamics for Peer-To-Peer overlay networks

    OpenAIRE

    Gkogkas, Alexandros; Roverso, Roberto; Haridi, Seif

    2011-01-01

    When evaluating Peer-to-Peer content distribution systems by means of simulation, it is of vital importance to correctly mimic the bandwidth dynamics behaviour of the underlying network. In this paper, we propose a scalable and accurate flow-level network simulation model based on an evolution of the classical progressive filling algorithm which follows the max-min fairness idea. We build on top of the current state of the art by applying an optimization to reduce the cost of each bandwidth a...

  19. 20 µm long slow-light Bragg reflector waveguide modulator with over 20 GHz modulation bandwidth

    Science.gov (United States)

    Gu, Xiaodong; Suzuki, Ayako; Matsutani, Akihiro; Koyama, Fumio

    2014-11-01

    A slow-light Bragg reflector waveguide optical modulator is designed and optimized for operations with a large modulation bandwidth and ultra-low power consumption. Devices with various modulator lengths are fabricated and characterized. Extinction ratios over 15 and 30 dB are obtained with reverse bias voltages below 1 and 1.5 V, respectively. In a 20 µm long modulator, a 3 dB modulation bandwidth exceeds 20 GHz with a bias voltage of only ?600 mV. The total energy consumption of the modulator is estimated to be lower than 100 fJ/bit, including both the load and dynamic power dissipations.

  20. Confidentiality & Authentication Mechanism for Biometric Information Transmitted over Low Bandwidth & Unreliable channel

    Directory of Open Access Journals (Sweden)

    Raju Singh

    2011-03-01

    Full Text Available The security of bio-metric information – finger print, retina mapping, DNA mapping and some otherchemical and biological modified genes related information - transfer through low bandwidth andunreliable or covert channel is challenging task. Therefore, Security of biometric information is essentialrequirement in this fast developing communication world. Thus, in this paper, we propose efficient andeffective mechanism for confidentiality and authentication for biometric information transmitted by usingarithmetic encoding representation over low bandwidth and unreliable channel. It enhances the speed ofencryption, decryption and authentication process. It uses arithmetic encoding scheme and public keycryptography e.g. modified version of RSA algorithm called RSA-2 algorithm.

  1. Bandwidth and wavelength-tunable optical bandpass filter based on silicon microring-MZI structure

    DEFF Research Database (Denmark)

    Ding, Yunhong; Pu, Minhao

    2011-01-01

    A novel and simple bandwidth and wavelength-tunable optical bandpass filter based on silicon microrings in a Mach-Zehnder interferometer (MZI) structure is proposed and demonstrated. In this filter design, the drop transmissions of two microring resonators are combined to provide the desired tunability. A detailed analysis and the design of the device are presented. The shape factor and extinction ratio of the filter are optimized by thermally controlling the phase difference between the two arms of the MZI. Simultaneous bandwidth and wavelength tunability with in-band ripple control is demonstrated by thermally tuning the resonance offset between the two microring resonators.

  2. The large analog bandwidth recorder and digitizer with ordered readout (LABRADOR) ASIC

    International Nuclear Information System (INIS)

    Three generations of full-custom analog integrated circuits designed for low-power, high-speed sampling of Radio-Frequency (RF) transients in excess of the Nyquist minimum have been developed. These 0.25?m CMOS devices are denoted the Large Analog Bandwidth Recorder and Digitizer with Ordered Readout (LABRADOR) ASICs and finally consist of nine channels of 260 deep sampling. Continuous sampling is provided with common stop capability. Input analog bandwidth is approximately 1 GHz and sampling speeds are adjustable from 0.02 to 3.7 GSa/s. Completely parallel internal conversion supports 12-bit digitization and readout of all 2340 cells in under 50?s

  3. Simple piezoelectric-actuated mirror with 180 kHz servo bandwidth

    CERN Document Server

    Briles, Travis C; Cingoz, Arman; Schibli, Thomas; Ye, Jun

    2010-01-01

    We present a high bandwidth piezoelectric-actuated mirror for length stabilization of an optical cavity. The actuator displays a transfer function with a flat amplitude response and greater than 135$^\\circ$ phase margin up to 200 kHz, allowing a 180 kHz unity gain frequency to be achieved in a closed servo loop. To the best of our knowledge, this actuator has achieved the largest servo bandwidth for a piezoelectric transducer (PZT). The actuator should be very useful in a wide variety of applications requiring precision control of optical lengths, including laser frequency stabilization, optical interferometers, and optical communications.

  4. DNA translocation measurements through low-capacitance solid-state nanopore chips at high bandwidths

    Science.gov (United States)

    Chien, Chen-Chi; Niedzwiecki, David; Machielse, Bartholomeus; Balan, Adrian; Lin, Jianxun; Ong, Peijie; Shepard, Kenneth; Drndic, Marija

    2015-03-01

    We perform DNA translocation measurements with low-noise solid state nanopore chips. We obtain higher ion current signal-to-noise ratio and better resolution in ion current signals than previously reported in solid state nanopores at high bandwidths with chip capacitance lowering techniques of applying extra insulation on the chip surface. We show measurements of ion current during translocation of DNA molecules through thin silicon nitride (SiN) nanopores of small diameters at megahertz bandwidths with enhanced ionic signal-to-noise ratios. We further discuss how these results possibly pave the way towards identifying intramolecular DNA sequences with solid-state nanopores.

  5. BANDWIDTH AND GAIN INCREMENT OF MICROSTRIP PATCH ANTENNA WITH SHIFTED ELLIPTICAL SLOT

    OpenAIRE

    ISHA PURI; ARCHANA AGRAWAL

    2011-01-01

    This paper describes the increment in Bandwidth and Gain of Rectangular Microstrip Patch antenna with Shifted Elliptical slot. First we have designed a Rectangular microstrip patch antenna. After that an elliptical slot is cut inside a rectangular patch which is shifted towards right. The results of both the designs are compared and it was found that an increase in the bandwidth of 21% and gain of 7.21 dBi is being achieved as that of a simple Rectangular microstrip patch antenna. Microstrip ...

  6. QoS Study Based On IEEE 802.16 Bandwidth Scheduling Strategy

    Directory of Open Access Journals (Sweden)

    Jun Tu

    2012-02-01

    Full Text Available on the basis of presenting the existing problems of the QoS multimedia services in IEEE802.16, this paper analyzes the disadvantage and advantage of current bandwidth scheduling strategy based on IEEE802.16. Then an improvement strategy of IEEE802.16 PMP network model is proposed based on existing strict priority scheduling strategy. Finally, through the simulation data, it proves that the strategy can ensure the QoS performance and fairness of bandwidth allocation between various multimedia communication services.  

  7. Chrome: Improving the Transmission Reliability by Bandwidth Optimization Using Hybrid Algorithm

    Directory of Open Access Journals (Sweden)

    Ajeeth Kumar J

    2013-04-01

    Full Text Available An approach to improve the transmission reliability by network bandwidth optimization using the hybrid algorithm called chrome. The main objective is to design an optimization algorithm to achieve bandwidth optimization in wireless networks using hybrid of Particle Swarm Optimizatio n (PSO and Genetic Algorithm (GA which improves the transmission reliability. In this approach, global search character of PSO and local search character of GA are used. In chrome algorithm, the PSO algorithm is used to search around the environment and where ever necessary the GA’s searching techniques are used for optimization

  8. Multiwavelength digital holography utilizing the space-bandwidth capacity-enhance

    Science.gov (United States)

    Tahara, Tatsuki; Kaku, Toru; Arai, Yasuhiko

    2014-11-01

    We demonstrate single-shot multiwavelength digital holography using a monochromatic image sensor and spacebandwidth capacity-enhance experimentally. Multiple wavelength information is multiplexed on the monochromatic image sensor plane in the space domain and is separated in the spatial frequency domain by utilizing the the spatial frequency of interference fringes. Both transmission and reflective multiwavelength digital holography systems can be constructed with a simple optical setup. The recordable space bandwidth utilized for object waves is extended by the space-bandwidth capacity-enhance. Both the three-dimensional and multiple wavelength information of an object with rough surface and a transparent specimen was recorded and reconstructed without unwanted image components.

  9. Absorption line shape recovery beyond the detection bandwidth limit: application to the Boltzmann constant determination

    CERN Document Server

    Rohart, François; Sow, Papa Lat Tabara; Tokunaga, Sean K; Chardonnet, Christian; Darquié, Benoît; Dinesan, H; Fasci, E; Castrillo, A; Gianfrani, L; Daussy, Christophe

    2014-01-01

    A theoretical model of the influence of detection bandwidth properties on observed line shapes in laser absorption spectroscopy is described. The model predicts artificial frequency shifts, extra broadenings and line asymmetries which must be taken into account in order to obtain accurate line parameters. The theoretical model is validated by experiments performed on H2O and NH3 molecular lines recorded by precision laser spectroscopy. Particular emphasis is put on the detection bandwidth adjustments required to perform a spectroscopic determination of the Boltzmann constant at the 1 ppm level of accuracy.

  10. Gap-Coupling: A Potential Method for Enhancing the Bandwidth of Microstrip Antennas

    Directory of Open Access Journals (Sweden)

    G. Singh

    2012-04-01

    Full Text Available In this paper, a technical review on gap-coupled microstrip antennas is presented. The gap-coupled microstrip antennas give a large bandwidth as compared to the conventional microstrip antennas. The method of bandwidth enhancement using gap-coupled microstrip antennas has been elaborated. The gap-coupled microstrip antennas also produce two resonances. The dual frequency operation of the gap-coupled microstrip antenna is also described. A research overview of gap-coupled microstrip antennas, challenges, types of gap-coupled microstrip antennas as well as numerical methods of calculating various parameters of the gap-coupled microstrip antennas are discussed in this paper.

  11. Frequency response and bandwidth in low-numerical-aperture step-index plastic optical fibers.

    Science.gov (United States)

    Savovi?, Svetislav; Drlja?a, Branko; Kova?evi?, Milan S; Djordjevich, Alexandar; Baji?, Jovan S; Stupar, Dragan Z; Stepniak, Grzegorz

    2014-10-20

    By experimental measurement and from a numerical solution to the time-dependent power flow equation, the frequency response, bandwidth, mode coupling, and mode-dependent attenuation are determined for a low-numerical-aperture (NA) plastic optical fiber. Frequency response and bandwidth are specified as a function of fiber length. Numerical results are verified against experimental measurements. Mode coupling and modal attenuation are found to differ substantially between two fiber varieties of the same type (both low-NA, step-index, and plastic), implying their preferential suitability that is application-specific. PMID:25402786

  12. 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 (?? / ? ~ 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 (?? ~ 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.

  13. Efficient "pure" blue OLEDs employing tetradentate Pt complexes with a narrow spectral bandwidth.

    Science.gov (United States)

    Fleetham, Tyler; Li, Guijie; Wen, Lele; Li, Jian

    2014-11-01

    Efficient deep-blue-emitting tetradentate platinum complexes with a narrow spectral bandwidth are presented, which demonstrate CIEx ? 0.15 and CIEy OLED) with 24.8% peak external quantum efficiency and CIE coordinates of (0.147, 0.079) is fabricated using PtON7-dtb. PMID:25207726

  14. Dynamic and balanced capacity allocation scheme with uniform bandwidth for OFDM-PON systems

    Science.gov (United States)

    Lei, Cheng; Chen, Hongwei; Chen, Minghua; Yu, Ying; Guo, Qiang; Yang, Sigang; Xie, Shizhong

    2015-03-01

    As the bitrate of orthogonal frequency division multiplexing passive optical network (OFDM-PON) system is continuously increasing, how to effectively allocate the system bandwidth among the huge number of optical network units (ONUs) is one of the key problems before OFDM-PON can be practical deployed. Unlike traditional bandwidth allocation scheme, in this paper, the transmission performance of single ONU is for the first time taken into consideration and optimized. To reduce the manufacturing complexity and fully utilize the processing ability of the receivers, the system bandwidth is equally distributed to the ONUs. Bit loading is used to allocate the total transmission capacity, and power loading is used to guarantee the ONUs have balanced transmission performance even if they operate at different bitrate. In this way, a dynamic and balanced capacity allocation scheme with uniform bandwidth for OFDM-PON systems can be realized. At last, an experimental system is established to verify the feasibility of the proposed scheme, and the influence that the scheme brings to the whole system is also analyzed.

  15. Gain-switched, Yb-doped, all-fiber laser with narrow bandwidth

    DEFF Research Database (Denmark)

    Larsen, Casper; Giesberts, Martin

    2013-01-01

    We demonstrate that an all-fiber, narrow bandwidth, high pulse energy pulsed laser can be constructed from commercially available components by applying gain-switching. After single-stage amplification the pulses are frequency doubled in ppSLT with high efficiency.

  16. Ultrabroad-bandwidth arbitrary radiofrequency waveform generation with a silicon photonic chip-based spectral shaper

    Science.gov (United States)

    Khan, Maroof H.; Shen, Hao; Xuan, Yi; Zhao, Lin; Xiao, Shijun; Leaird, Daniel E.; Weiner, Andrew M.; Qi, Minghao

    2010-02-01

    Ultrabroad-bandwidth radiofrequency pulses offer significant applications potential, such as increased data transmission rate and multipath tolerance in wireless communications. Such ultrabroad-bandwidth pulses are inherently difficult to generate with chip-based electronics due to limits in digital-to-analog converter technology and high timing jitter. Photonic means of radiofrequency waveform generation, for example, by spectral shaping and frequency-time mapping, can overcome the bandwidth limit in electronic generation. However, previous bulk optic systems for radiofrequency arbitrary waveform generation do not offer the integration advantage of electronics. Here, we report a chip-scale, fully programmable spectral shaper consisting of cascaded multiple-channel microring resonators, on a silicon photonics platform that is compatible with electronic integrated circuit technology. Using such a spectral shaper, we demonstrate the generation of burst radiofrequency waveforms with programmable time-dependent amplitude, frequency and phase profiles, for frequencies up to 60 GHz. Our demonstration suggests potential for chip-scale photonic generation of ultrabroad-bandwidth arbitrary radiofrequency waveforms.

  17. Bandwidth Efficient Three-User Cooperative Diversity Scheme Based on Relaying Superposition Symbols

    Directory of Open Access Journals (Sweden)

    Xiufeng JIN

    2009-04-01

    Full Text Available Recently, Cooperative diversity in wireless communication systems has gained much attention. A simple two-user cooperative diversity scheme called decode-and-forward cooperation scheme has been presented by Laneman (2004. Each user has one partner to decode its information and retransmit it by employing repeti-tion coding. This scheme can offer diversity order of two. But the bandwidth efficiency is low. In this paper, we propose a bandwidth efficient three-user cooperative diversity scheme based on relaying superposition symbols. Each user has two partners and each partner relays superposition symbols of the other two users instead of repetition. Thus, the bandwidth efficiency is improved compared to the baseline decode- and-forward cooperative diversity scheme presented by Laneman. Moreover, the proposed scheme can also offer diversity order of two. Then, in order to improve the system performance, a new constellation labeling for the superposition 8PSK modulation is designed. It is a simple way to exploit the symbol mapping diver-sity and a gain of about 2 dB can be obtained. Furthermore, the performance improvement comes at no addi-tional power or bandwidth expense.

  18. Technique for tuning center frequency of HTS microstrip filters without significantly changing bandwidth

    Science.gov (United States)

    Sekiya, N.; Nakagawa, Y.; Saito, A.; Ohshima, S.

    2009-10-01

    We have developed a technique for tuning high-temperature superconducting (HTS) microstrip filters in which additional electric pads are placed at the open ends of the resonators for tuning the center frequency. Pads are placed along one side of the open ends of the resonators to enable the effective lengths of the resonators to be adjusted, thereby shifting the center frequency. Pads are also placed around the I/O coupled-line elements to enable the coupling strength between the coupled-line and resonator to be adjusted, thereby reducing the insertion loss caused by tuning. The pads consist of line-and-space patterns. The former are electrically connected to the resonators, and the latter are electrically connected to the coupled-line elements. Simulated application of this technique to a 3-pole superconducting microstrip combline bandpass filter with half-wavelength resonators, a 5.0-GHz center frequency, and a 120-MHz 3-dB bandwidth shifted the bandwidth 500 MHz. However, the 3-dB bandwidth was reduced about 14 MHz. Use of a modified 3-pole microstrip interdigital bandpass filter mitigated the reduction to 2 MHz. Using this modified filter with additional electric pads is thus an effective way to tune the center frequency of HTS bandpass filters without significantly changing the bandwidth.

  19. Technique for tuning center frequency of HTS microstrip filters without significantly changing bandwidth

    International Nuclear Information System (INIS)

    We have developed a technique for tuning high-temperature superconducting (HTS) microstrip filters in which additional electric pads are placed at the open ends of the resonators for tuning the center frequency. Pads are placed along one side of the open ends of the resonators to enable the effective lengths of the resonators to be adjusted, thereby shifting the center frequency. Pads are also placed around the I/O coupled-line elements to enable the coupling strength between the coupled-line and resonator to be adjusted, thereby reducing the insertion loss caused by tuning. The pads consist of line-and-space patterns. The former are electrically connected to the resonators, and the latter are electrically connected to the coupled-line elements. Simulated application of this technique to a 3-pole superconducting microstrip combline bandpass filter with half-wavelength resonators, a 5.0-GHz center frequency, and a 120-MHz 3-dB bandwidth shifted the bandwidth 500 MHz. However, the 3-dB bandwidth was reduced about 14 MHz. Use of a modified 3-pole microstrip interdigital bandpass filter mitigated the reduction to 2 MHz. Using this modified filter with additional electric pads is thus an effective way to tune the center frequency of HTS bandpass filters without significantly changing the bandwidth.

  20. 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.

  1. TOLPA (Tripod Omnidirectional Low Profile Antenna): a vertically polarized antenna with 90% bandwidth

    OpenAIRE

    Zu?rcher, J. -f

    2013-01-01

    A new vertically polarized omnidirectional antenna, inspired by an old design, has been studied, optimized, realized and measured. With a radiation pattern similar to the classical monopole on a ground plane, the proposed antenna concept provides a much larger bandwidth and a very low profile. This antenna has numerous potential applications for mobile communications, UWB and others.

  2. 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.

  3. An Improved QoS Multipath Routing Using Bandwidth Estimation and Rate Adaptation

    Directory of Open Access Journals (Sweden)

    S. Suganya

    2014-06-01

    Full Text Available Mobile Adhoc Networks (MANETs are composed of nodes which communicate with one another without network infrastructure. Their advantage being that they can be used in isolation or along with wired infrastructure, usually via a gateway node to ensure traffic relay for both networks. Quality of Service (QoS is harder to ensure in ad hoc networks than in other network types, as wireless bandwidth is shared by adjacent nodes with network topology changing as nodes move. Most QoS protocols are implemented for specific scenarios and consider parameters such as network topologies, bandwidth, mobility, security and so on. This work proposes a novel multipath routing protocol which is an extension of AOMDV by discovering routes based on available bandwidth and rate adaptation. The method with Hello message box is used to calculate available bandwidth for a route. Relative Fairness and Optimized Throughput is an approach for rate adaptation in this paper which is to ensure fairness and allow nodes to adapt transmission rates and contention windows to channel quality. In sequence this is determined by calculating the access probability of a channel for each node in a distributed manner approximating successful and failed transmissions.

  4. Design of zone-based bandwidth management scheme in IEEE 802.16 multi-hop relay networks

    Directory of Open Access Journals (Sweden)

    Chen Kuo-Yang

    2011-01-01

    Full Text Available Abstract IEEE 802.16 Wireless Network technology is a hot research issue in recent years. It provides wider coverage of radio and higher speed wireless access, and Quality-of-Service plays an important part in the standard. For mobile multi-hop wireless network, IEEE 802.16j/MR network not only can supply large area wireless deployment, but also can provide high quality network service to mobile users. Although Mobile QoS supporting has been extensively investigated, Mobile QoS supporting in the IEEE 802.16-MR network is relatively unexplored. In this article, the probability of a mobile user who visits a Relay Station (RS is known beforehand. With the visiting probability at each RS and the system specified size of the range for bandwidth allocation, Base Station (BS can calculate the required bandwidth to meet the mobile user's demand and allocate appropriate bandwidth for a mobile user roaming in the range of the bandwidth allocation. The range of bandwidth allocation for mobile users is called the Zone in this article, which includes the user's current RS and the nearby RSs. The proposed scheme is therefore called Zone-based bandwidth management scheme. The simulation results demonstrate that Zone-based bandwidth management scheme can reduce QoS degradation and bandwidth re-allocation overhead.

  5. All-optical characterization of large-signal modulation bandwidth of a monolithically integrated DFB-EA

    DEFF Research Database (Denmark)

    Blaaberg, SØren; Mulvad, Hans Christian Hansen

    2009-01-01

    We use an all-optical method to characterize the modulation bandwidth of a DFB-EA designed for 100 Gb/s Ethernet. In a large-signal wavelength conversion set-up, we show the device has an all-optical bandwidth of 83 GHz.

  6. Development of high bandwidth powered resonance tube actuators with feedback control

    Science.gov (United States)

    Raman, G.; Khanafseh, S.; Cain, A. B.; Kerschen, E.

    2004-01-01

    A high bandwidth powered resonance tube (PRT) actuator potentially useful for noise and flow control applications was developed. High bandwidth allows use of the same actuator at various locations on an aircraft and over a range of flight speeds. The actuator selected for bandwidth enhancement was the PRT actuator, which is an adaptation of the Hartmann whistle. The device is capable of producing high-frequency and high-amplitude pressure and velocity perturbations for active flow control applications. Our detailed experiments aimed at understanding the PRT phenomenon are complemented by an improved analytical model and direct numerical simulations. We provide a detailed characterization of the unsteady pressures in the nearfield of the actuator using phase averaged pressure measurements. The measurements revealed that propagating fluctuations at 9 kHz were biased towards the upstream direction (relative to the supply jet). A complementary computational study validated by our experiments was useful in simulating the details in the region between the supply jet and the resonance tube where it was difficult to gather experimental data. High bandwidth was obtained by varying the depth of the resonance tube that determines the frequency produced by the device. Our actuator could produce frequencies ranging from 1600 to 15,000 Hz at amplitudes as high as 160 dB near the source. The frequency variation with depth is predicted well by the quarter wavelength formula for deep tubes but the formula becomes increasingly inaccurate as the tube depth is decreased. An improved analytical model was developed, in which the compliance and mass of the fluid in the integration slot is incorporated into the prediction of resonance frequencies of the system. Finally a feedback controller that varied both the resonance tube depth and spacing to converge on a desired frequency was developed and demonstrated. We are optimistic that numerous potential applications exist for such high bandwidth high dynamic range actuators.

  7. Improving QoS Of WiMAX By On_Demand Bandwidth Allocation Based On PMP Mode

    Directory of Open Access Journals (Sweden)

    ZhenTao Sun

    2011-10-01

    Full Text Available Abstract—The bandwidth allocation in both wired and wireless networks has posed great challenges to network engineers for improving desirable Quality of Service (QoS, Bandwidth allocation is always an important element for improve QoS of network. Despite this, IEEE 802.16e-2005 does not have a bandwidth allocation algorithm or mechanism to support (worldwide interoperability for microwave access WiMAX network presently. This includes both uplink (UL and downlink (DL directions. Thus, most of researches are focusing in this area. In order to improve the QoS of WiMAX demand, the total capacity of WiMAX system must be optimized. Thereby, in this research, a new bandwidth allocation mechanism for WiMAX network is proposed, called On Demand Bandwidth Allocation (ODBA. The proposed mechanism design has the management module in the Subscribe Station (SS, which is for management UL bandwidth, and one new module in the Base Station (BS. This includes UL/DL bandwidth allocation and service flow schedule. We tested the new mechanism by running in the simulation of OMNET++. As the results show that the ODBA mechanism has improve the scheduled probability (SP and increase the throughput of WiMAX network

  8. 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.

  9. Bandwidth Limitations in Characterization of High Intensity Focused Ultrasound Fields in the Presence of Shocks

    Science.gov (United States)

    Khokhlova, V. A.; Bessonova, O. V.; Soneson, J. E.; Canney, M. S.; Bailey, M. R.; Crum, L. A.

    2010-03-01

    Nonlinear propagation effects result in the formation of weak shocks in high intensity focused ultrasound (HIFU) fields. When shocks are present, the wave spectrum consists of hundreds of harmonics. In practice, shock waves are modeled using a finite number of harmonics and measured with hydrophones that have limited bandwidths. The goal of this work was to determine how many harmonics are necessary to model or measure peak pressures, intensity, and heat deposition rates of the HIFU fields. Numerical solutions of the Khokhlov-Zabolotskaya-Kuznetzov-type (KZK) nonlinear parabolic equation were obtained using two independent algorithms, compared, and analyzed for nonlinear propagation in water, in gel phantom, and in tissue. Measurements were performed in the focus of the HIFU field in the same media using fiber optic probe hydrophones of various bandwidths. Experimental data were compared to the simulation results.

  10. Generation of narrow-bandwidth, tunable, coherent xuv radiation using high-order harmonic generation

    International Nuclear Information System (INIS)

    We theoretically demonstrate the generation of wavelength-tunable, narrow-bandwidth extreme-ultraviolet (xuv) radiation by high-order harmonic generation (HHG) driven by an orthogonally polarized two-color laser field, which is composed of a 10-fs, 1500-nm laser pulse and a 40-fs, 2400-nm laser pulse. By performing classical analysis, we reveal that the rapid change of electron wave-packet dynamics at a subcycle time scale confines high-order harmonic emission to a small spectral region, leading to the generation of narrow-bandwidth xuv radiation. Furthermore, the central wavelength of the xuv radiation can be continuously tuned over a wide range by changing either the peak intensity of the driver laser or the amplitude ratio between the two laser fields at different wavelengths. It is also verified that the use of driver pulses at longer wavelengths leads to a better spectral confinement of the xuv radiation.

  11. Dynamic Bandwidth Allocation Based on Online Traffic Prediction for Real-Time MPEG-4 Video Streams

    Directory of Open Access Journals (Sweden)

    Mei Han

    2007-01-01

    Full Text Available The distinct characteristics of variable bit rate (VBR video traffic and its quality of service (QoS constraints have posed a unique challenge on network resource allocation and management for future integrated networks. Dynamic bandwidth allocation attempts to adaptively allocate resources to capture the burstiness of VBR video traffic, and therefore could potentially increase network utilization substantially while still satisfying the desired QoS requirements. We focus on prediction-based dynamic bandwidth allocation. In this context, the multiresolution learning neural-network-based traffic predictor is rigorously examined. A well-known-heuristic based approach RED-VBR scheme is used as a baseline for performance evaluation. Simulations using real-world MPEG-4 VBR video traces are conducted, and a comprehensive performance metrics is presented. In addition, a new concept of renegotiation control is introduced and a novel renegotiation control algorithm based on binary exponential backoff (BEB is proposed to efficiently reduce renegotiation frequency.

  12. Experimental demonstration of an improved EPON architecture using OFDMA for bandwidth scalable LAN emulation

    DEFF Research Database (Denmark)

    Deng, Lei; Zhao, Ying

    2011-01-01

    We propose and demonstrate an improved Ethernet passive optical network (EPON) architecture supporting bandwidth-scalable physical layer local area network (LAN) emulation. Due to the use of orthogonal frequency division multiple access (OFDMA) technology for the LAN traffic transmission, there is no need to change the existing EPON architecture. Only one receiver at each optical network unit (ONU) is required to detect both LAN traffic and EPON downstream traffic, which makes the proposed system simple and cost-effective. Moreover, flexible assignment of LAN traffic bandwidth is realized by allocating different number of subcarriers or using different modulation formats. The 250Mb/s 4-quadrature amplitude modulation (4-QAM) and 500Mb/s 16-QAM OFDM LAN traffic are successfully emulated with the EPON traffic in our experiment.

  13. Enhancing the bandwidth of gravitational-wave detectors with unstable optomechanical filters

    CERN Document Server

    Miao, Haixing; Zhao, Chunnong; Chen, Yanbei

    2015-01-01

    For gravitational-wave interferometric detectors, there is a tradeoff between the detector bandwidth and peak sensitivity when focusing on the shot noise level. This has to do with the frequency-dependent propagation phase lag (positive dispersion) of the signal. We consider embedding an active unstable filter---a cavity-assisted optomechanical device operating in the instability regime---inside the interferometer to compensate the phase, and using feedback control to stabilize the entire system. We show that this scheme in principle can enhance the bandwidth without sacrificing the peak sensitivity. However, there is one practical difficulty for implementing it due to the thermal fluctuation of the mechanical oscillator in the optomechanical filter, which puts a very stringent requirement on the environmental temperature and the mechanical quality factor.

  14. Optimal Resource Allocation and Relay Selection in Bandwidth and Time Exchange Based Cooperative Forwarding

    CERN Document Server

    Islam, Muhammad Nazmul; Kompella, Sastry

    2011-01-01

    In this paper, we investigate joint optimal relay selection and resource allocation that are fundamental to the understanding of bandwidth exchange (BE) and time exchange (TE) enabled incentivized cooperative forwarding in wireless networks. We consider a network where N nodes transmit data in the uplink to an access point (AP) or base station (BS). We first consider the scenario where each node gets an initial amount (equal, optimal or arbitrary) of resource in the form of bandwidth or time, and uses this resource as a flexible incentive for two hop relaying. We focus on ?-fair network utility maximization (NUM) and total power minimization in this environment. For both BE and TE, we show the concavity or convexity of the resource allocation problem for a fixed relay set. Defining the link weights of each relay pair as the utility gain due to cooperation (over noncooperation), we show that the optimal relay selection, often a combinatorially cumbersome problem, reduces to the maximum weighted matching (MWM) ...

  15. Atomic Faraday filter with equivalent noise bandwidth less than 1 GHz

    CERN Document Server

    Zentile, Mark A; Keaveney, James; Adams, Charles S; Hughes, Ifan G

    2015-01-01

    We demonstrate an atomic bandpass optical filter with an equivalent noise bandwidth less than 1 GHz using the D$_1$ line in a cesium vapor. We use the ElecSus computer program to find optimal experimental parameters, and find that for important quantities the cesium D$_1$ line clearly outperforms other alkali metals on either D-lines. The filter simultaneously achieves a peak transmission of 77%, a passband of 310 MHz and an equivalent noise bandwidth of 0.96 GHz, for a magnetic field of 45.3 gauss and a temperature of 68.0$\\,^\\circ$C. Experimentally, the prediction from the model is verified. The experiment and theoretical predictions show excellent agreement.

  16. Real-time full bandwidth measurement of spectral noise in supercontinuum generation

    CERN Document Server

    Wetzel, B; Larger, L; Lacourt, P A; Merolla, J M; Sylvestre, T; Kudlinski, A; Mussot, A; Genty, G; Dias, F; Dudley, J M; 10.1038/srep00882

    2012-01-01

    The ability to measure real-time fluctuations of ultrashort pulses propagating in optical fiber has provided significant insights into fundamental dynamical effects such as modulation instability and the formation of frequency-shifting rogue wave solitons. We report here a detailed study of real-time fluctuations across the full bandwidth of a fiber supercontinuum which directly reveals the significant variation in measured noise statistics across the spectrum, and which allows us to study correlations between widely separated spectral components. For two different propagation distances corresponding to the onset phase of spectral broadening and the fully-developed supercontinuum, we measure real time noise across the supercontinuum bandwidth, and we quantify the supercontinuum noise using statistical higher-order moments and a frequency-dependent intensity correlation map. We identify correlated spectral regions within the supercontinuum associated with simultaneous sideband generation, as well as signatures...

  17. BANDWIDTH AND GAIN INCREMENT OF MICROSTRIP PATCH ANTENNA WITH SHIFTED ELLIPTICAL SLOT

    Directory of Open Access Journals (Sweden)

    ISHA PURI

    2011-07-01

    Full Text Available This paper describes the increment in Bandwidth and Gain of Rectangular Microstrip Patch antenna with Shifted Elliptical slot. First we have designed a Rectangular microstrip patch antenna. After that an elliptical slot is cut inside a rectangular patch which is shifted towards right. The results of both the designs are compared and it was found that an increase in the bandwidth of 21% and gain of 7.21 dBi is being achieved as that of a simple Rectangular microstrip patch antenna. Microstrip patch antenna is designed on a Duroid 5880 substrate with a dielectric constant of 2.2. The antenna is fed by a Coaxial probe feed. The antenna designs and performances are analyzed using Zealand IE3D software. The antenna can be used for many modern communication systems.

  18. Dual band-notched monopole antenna with enhanced bandwidth for ultra-wideband wireless communications

    Directory of Open Access Journals (Sweden)

    Mohammad Akbari

    2014-08-01

    Full Text Available A new configuration of an ultra-wideband (UWB dual band-notched antenna is presented. The designed geometry consists of octagonal radiating patch, a 50 ? microstrip feed-line on the front and an asymmetric partial ground on the back. For impedance bandwidth enhancement, a unilateral stepped structure is utilised on the ground. By etching two E-shaped slots connected to each other on the radiating patch and applying E-shaped defected ground structure on the back, dual notched bands are achieved. The antenna is printed on a low profile FR4 substrate with a compact size of 25 × 18 × 1 mm^3. The experimental results indicate that the antenna has an impedance bandwidth from 2.55 to 21.65 GHz for voltage standing wave ratio ?2, except the notched bands on worldwide interoperability for microwave access and wireless local area network bands. Moreover, stable radiation patterns and gains within the operating band are shown.

  19. Linear and Nonlinear Analysis of Magnetic Bearing Bandwidth Due to Eddy Current Limitations

    Science.gov (United States)

    Kenny, Andrew; Palazzolo, Alan

    2000-01-01

    Finite element analysis was used to study the bandwidth of alloy hyperco50a and silicon iron laminated rotors and stators in magnetic bearings. A three dimensional model was made of a heteropolar bearing in which all the flux circulated in the plane of the rotor and stator laminate. A three dimensional model of a plate similar to the region of a pole near the gap was also studied with a very fine mesh. Nonlinear time transient solutions for the net flux carried by the plate were compared to steady state time harmonic solutions. Both linear and quasi-nonlinear steady state time harmonic solutions were calculated and compared. The finite element solutions for power loss and flux bandwidth were compared to those determined from classical analytical solutions to Maxwell's equations.

  20. Slow light with large group index-bandwidth product in ellipse-hole photonic crystal waveguides.

    Science.gov (United States)

    Han, Xu; Wang, Tao; Tang, Jian; Liu, Bo; Wang, BoYun; He, Yu; Zhu, Youjiang

    2015-02-20

    In this study, we propose a new type of slow light photonic crystal waveguide structure to achieve wideband slow light with low dispersion. The waveguide is based on a triangular lattice ellipse-hole photonic crystal imposed simply by a selective altering of the locations of the holes adjacent to the line defect. Under a constant group index criterion of ±10% variation, when group indices are nearly constants of 54, 69, and 80, their corresponding bandwidths of the flat band reach 12.7, 10.0, and 8.6 nm around 1550 nm, respectively. A nearly constant large group index-bandwidth product of 0.44 is achieved for all cases. Low dispersion slow light propagation is confirmed by studying the relative temporal pulse-width spreading with the two-dimensional finite-difference time-domain method. PMID:25968223

  1. Dispersion management of anisotropic metamirror for super-octave bandwidth polarization conversion

    Science.gov (United States)

    Guo, Yinghui; Wang, Yanqin; Pu, Mingbo; Zhao, Zeyu; Wu, Xiaoyu; Ma, Xiaoliang; Wang, Changtao; Yan, Lianshan; Luo, Xiangang

    2015-02-01

    Dispersion engineering of metamaterials is critical yet not fully released in applications where broadband and multispectral responses are desirable. Here we propose a strategy to circumvent the bandwidth limitation of metamaterials by implementing two-dimensional dispersion engineering in the meta-atoms. Lorentzian resonances are exploited as building blocks in both dimensions of the dedicatedly designed meta-atoms to construct the expected dispersion. We validated this strategy by designing and fabricating an anisotropic metamirror, which can accomplish achromatic polarization transformation in 4-octave bandwidth (two times of previous broadband converters). This work not only paves the way for broadband metamaterials design but also inspire potential applications of dispersion management in nano-photonics.

  2. Tunable single Stokes extraction from 20 GHz Brillouin fiber laser using ultranarrow bandwidth optical filter.

    Science.gov (United States)

    Ahmad, H; Razak, N F; Zulkifli, M Z; Ismail, M F; Munajat, Y; Harun, S W

    2014-10-10

    The individual extraction of a Brillouin Stokes line from a 20 GHz comb generated from the compact configuration of a multiwavelength Brillouin fiber ring laser configuration has been achieved using an ultranarrow bandwidth (UNB) optical filter. The narrowest bandwidth transmission of a UNB optical filter that is 50 pm is used in order to get particular Stokes. The Stokes filtered is in the wavelength range of 1549.768-1551.016 nm. High SNR within the range of 54.97-11.73 dB with almost nil peak power loss being obtained was monitored by a 0.16 pm optical spectrum analyzer, giving convincing results. Relatively, the proposed configuration could provide wide tunability and narrow selection of the Brillouin Stokes. PMID:25322403

  3. Bandwidth optimization of compact microstrip antenna for PCS/DCS/bluetooth application

    Science.gov (United States)

    Singh, Vinod; Ali, Zakir; Ayub, Shahanaz; Singh, Ashutosh

    2014-09-01

    A novel compact broadband microstrip patch antenna is presented for various wireless applications. The proposed antenna has been fabricated and the impedance bandwidth and radiation pattern are measured. The simulated and measured antenna characteristics along with radiation pattern and gain are presented. It is stated that the proposed designed antenna can completely cover the required band widths of Digital communication system (DCS 1.71-1.88 GHz), Personal communication system (PCS 1.85-1.88 GHz) and IEEE 802.11b/g (2.4-2.485 GHz) with satisfactory radiation characteristics. The Experimental result shows that the proposed antenna presents a bandwidth 60.25% covering the range of 1.431-2.665 GHz with the maximum radiation efficiency 90%.

  4. High-Fidelity Polarization Storage in a Gigahertz Bandwidth Quantum Memory

    CERN Document Server

    England, D G; Champion, T F M; Reim, K F; Lee, K C; Sprague, M R; Jin, X -M; Langford, N K; Kolthammer, W S; Nunn, J; Walmsley, I A

    2011-01-01

    We demonstrate a dual-rail optical Raman memory inside a polarization interferometer; this enables us to store polarization-encoded information at GHz bandwidths in a room-temperature atomic ensemble. By performing full process tomography on the system we measure up to 97\\pm1% process fidelity for the storage and retrieval process. At longer storage times, the process fidelity remains high, despite a loss of efficiency. The fidelity is 86\\pm4% for 1.5 \\mu s storage time, which is 5,000 times the pulse duration. Hence high fidelity is combined with a large time-bandwidth product. This high performance, with an experimentally simple setup, demonstrates the suitability of the Raman memory for integration into large-scale quantum networks.

  5. Three-Pole Tunable Bandpass Filters With Constant Fractional Bandwidth Using Mixed Comb-line Resonators

    Science.gov (United States)

    Zhao, Zhiyuan; Chen, Jiang; Yang, Lin; Chen, Kunhe

    2014-09-01

    A novel three-pole tunable bandpass filter using mixed combline resonators with a center frequency band of 0.9-1.8 GHz is proposed in this paper. The varactor-tuned filter is designed on a Rogers substrate with ?r = 2.2 and h = 1 mm, with 1-dB fractional bandwidth of 11% ± 0.6% (absolute bandwidth 97 MHz to 187.2 MHz). Its insertion loss is varying from 4.58 dB to 2.86 dB and return loss is better than 10 dB within the tuning frequency range. The measured third-order inter-modulation intercept point and 1-dB power compression point at midband (1.35 GHz) are higher than 17 and 8 dBm, respectively. The measured results show good agreement with the simulated ones.

  6. Steady-state entanglement of cavity arrays in finite-bandwidth squeezed reservoirs

    CERN Document Server

    Zippilli, Stefano

    2014-01-01

    When two chains of quantum systems are driven at their ends by a two-mode squeezed reservoir, they approach a steady state characterized by the formation of many entangled pairs. Each pair is made of one element of the first and one of the second chain. This effect has been already predicted under the assumption of broadband squeezing. Here we investigate the situation of finite-bandwidth reservoirs. This is done by modeling the driving bath as the output field of a non-degenerate parametric oscillator. The resulting non-Markovian dynamics is studied within the theoretical framework of cascade open quantum systems. It is shown that the formation of pair-entangled structures occurs as long as the normal-mode splitting of the arrays does not overcome the squeezing bandwidth of the reservoir.

  7. 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.

  8. Improving bandwidth rectangular patch antenna using different thickness of dielectric substrate

    Directory of Open Access Journals (Sweden)

    Karim A. Hamad

    2011-04-01

    Full Text Available Microstrip patch antenna has some drawbacks of low efficiency, narrow band (<5%, and surface wave losses. In this paper the solution method was used different thickness of dielectric substrate (h= 4, 6 and 8 mm to increase bandwidth, the simulated results for rectangular give bandwidth of (200 MHZ in case (h=6mm.A rectangular micro strip patch antenna that meets the requirement of operation at (2.4 GHZ, the proposed configurations are simulated and analyzed using microwave office 2000 software package. The VSWR, input impedance, radiation patterns and S11 performance are used for the analysis of the different configurations. Feed point on the patch that gives a good match of 50 ohm, input impedance was found by a method of trial and error.

  9. Image-quality improvement in space-bandwidth capacity-enhanced digital holography

    Science.gov (United States)

    Tahara, Tatsuki; Takahashi, Yuki; Arai, Yasuhiko

    2014-11-01

    A method for improving the quality of the reconstructed image in space-bandwidth capacity-enhanced (SPACE) digital holography is proposed. SPACE digital holography is based on an off-axis configuration and is a technique for capturing an object wave with wide space-bandwidth product by introducing high spatial-carrier frequency, intentional aliasing, periodicity of a digital signal, and the optimal arrangements of the angle difference and object wave spectrum. In this paper, the severe spectrum attenuation caused by the integral of fine interference fringes in a pixel according to the sinc function is corrected by using spatial frequency analysis. Numerical and experimental results show the effectiveness of the proposed method.

  10. Single-shot rotational Raman thermometry for turbulent flames using a low-resolution bandwidth technique

    Science.gov (United States)

    Kojima, Jun; Nguyen, Quang-Viet

    2008-01-01

    An alternative optical thermometry technique that utilizes the low-resolution (order 101 cm-1) pure-rotational spontaneous Raman scattering of air is developed to aid single-shot multiscalar measurements in turbulent combustion studies. Temperature measurements are realized by correlating the measured envelope bandwidth of the pure-rotational manifold of the N2/O2 spectrum with a theoretical prediction of a species-weighted bandwidth. By coupling this thermometry technique with conventional vibrational Raman scattering for species determination, we demonstrate quantitative spatially resolved, single-shot measurements of the temperature and fuel/oxidizer concentrations in a high-pressure turbulent CH4-air flame. Our technique provides not only an effective means of validating other temperature measurement methods, but also serves as a secondary thermometry technique in cases where the anti-Stokes vibrational N2 Raman signals are too low for a conventional vibrational temperature analysis.

  11. Transmit Signal and Bandwidth Optimization in Multiple-Antenna Relay Channels

    CERN Document Server

    Ng, Chris T K

    2010-01-01

    Transmit signal and bandwidth optimization is considered in multiple-antenna relay channels. Assuming all terminals have channel state information, the cut-set capacity upper bound and decode-and-forward rate under full-duplex relaying are evaluated by formulating them as convex optimization problems. For half-duplex relays, bandwidth allocation and transmit signals are optimized jointly. Moreover, achievable rates based on the compress-and-forward transmission strategy are presented using rate-distortion and Wyner-Ziv compression schemes. It is observed that when the relay is close to the source, decode-and-forward is almost optimal, whereas compress-and-forward achieves good performance when the relay is close to the destination.

  12. Effects of Bandwidth, Compression Speed, and Gain at High Frequencies on Preferences for Amplified Music

    OpenAIRE

    Moore, Brian C.J.

    2012-01-01

    This article reviews a series of studies on the factors influencing sound quality preferences, mostly for jazz and classical music stimuli. The data were obtained using ratings of individual stimuli or using the method of paired comparisons. For normal-hearing participants, the highest ratings of sound quality were obtained when the reproduction bandwidth was wide (55 to 16000 Hz) and ripples in the frequency response were small (less than ± 5 dB). For hearing-impaired participants listening ...

  13. Enhancing Interaction between Smartphones and Web Services on Cloud for Improved Bandwidth and Latency

    OpenAIRE

    Mandeep Singh,; Mr.Kanwalvir Singh Dhindsa

    2013-01-01

    As cellular network infrastructures are improving day by day; they are becoming the ideal clientsto access the any Web resources, especially Internet Based Services. However, Smartphones have certainlimitations in connecting smartphone based devices to existing Internet based Services. This paper mainlyfocuses on focuses on the following limitations: connection loss, bandwidth, latency, and limited resources.This paper implements a platform independent architecture for connecting smartphones ...

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

    DEFF Research Database (Denmark)

    Lorke, Michael; Nielsen, Torben Roland

    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 counterintuitive effect is investigated using a microscopic semiconductor model. The resulting guidelines for possible optimizations of quantum-dot based nanocavity laser devices are given.

  15. High bandwidth heat transfer and optical measurements in an I.C. engine

    OpenAIRE

    Wilson, TS; Bryanston-Cross, PJ; Chana, KS; Dunkley, P; Jones, TV; Hannah, P

    2001-01-01

    Three independent measurements have been used to investigate combustion within a single cylinder four-stroke research engine operating at low load. THIN FILM GAUGES - Heat transfer is determined using platinum thin film resistance thermometers exposed to the combustion gases. These give a frequency response of greater than 100kHz; hence can track heat transfer rate changes on the piston and cylinder head surfaces adequately. The thin film gauges overcome the problems of low bandwidths and lar...

  16. Robustness and Actuator Bandwidth of MRP-Based Sliding Mode Control for Spacecraft Attitude Control Problems

    Science.gov (United States)

    Keum, Jung-Hoon; Ra, Sung-Woong

    2009-12-01

    Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.

  17. Delay Minimization in Varying-Bandwidth Direct Multicast with Side Information

    OpenAIRE

    Dau, Son Hoang; Dong, Zheng; Yuen, Chau; Chan, Terence H.

    2013-01-01

    We study the delay minimization in a direct multicast communication scheme where a base station wishes to transmit a set of original packets to a group of clients. Each of the clients already has in its cache a subset of the original packets, and requests for all the remaining packets. The base station communicates directly with the clients by broadcasting information to them. Assume that bandwidths vary between the station and different clients. We propose a method to minim...

  18. Bandwidth Analysis of Bootstrap Transimpedance Amplifier for Optical Free Space Receiver

    OpenAIRE

    Ramli, A.; Rais, S. S.; Idrus, S. M.

    2008-01-01

    Free Space Optic (FSO) or optical wireless link operates in high noise environments. On the other hand, theperformance is subjected to several atmospheric factors like environmental temperature, fog, smoke, haze and rain. Signalto-noise ratio (SNR) can vary radically with the distance and ambient noise. A good sensitivity and a broad bandwidth willhabitually use a small photodetection area where the aperture is small. However, FSO optical receiver requires a largeaperture and accordingly, to ...

  19. Real-time full bandwidth measurement of spectral noise in supercontinuum generation

    OpenAIRE

    Wetzel, B.; Stefani, A.; Larger, L.; Lacourt, P. A.; Merolla, J. M.; Sylvestre, T.; Kudlinski, A.; Mussot, A.; Genty, G.; Dias, F.; Dudley, J. M.

    2012-01-01

    The ability to measure real-time fluctuations of ultrashort pulses propagating in optical fiber has provided significant insights into fundamental dynamical effects such as modulation instability and the formation of frequency-shifting rogue wave solitons. We report here a detailed study of real-time fluctuations across the full bandwidth of a fiber supercontinuum which directly reveals the significant variation in measured noise statistics across the spectrum, and which all...

  20. Broad bandwidth of perceptual learning in the visual system of adults with anisometropic amblyopia

    OpenAIRE

    Huang, Chang-Bing; Zhou, Yifeng; Lu, Zhong-Lin

    2008-01-01

    Recent studies have demonstrated that training adult amblyopes in simple visual tasks leads to significant improvements of their spatial vision. One critical question is: How much can training with one particular stimulus and task generalize to other stimuli and tasks? In this study, we estimated the bandwidth of perceptual learning in teenage and adult observers with anisometropic amblyopia and compared it to that of normal observers. We measured and compared contrast sensitivity functions?...

  1. Bandwidth and dynamic range of a widely tunable Josephson parametric amplifier

    OpenAIRE

    Castellanos-Beltran, M. A.; Irwin, K. D.; Vale, L. R.; Hilton, G.C.; Lehnert, K.W.

    2009-01-01

    The ability to manipulate quantum information encoded in microwave fields has led to a renewed interest in Josephson parametric amplifiers (JPAs). For these applications the ability of JPAs to amplify signals with the least amount of added noise is critical. Unfortunately JPAs are typically narrow band amplifiers with small dynamic range. It is therefore important to understand the bandwidth and dynamic range of any particular JPA in order to determine if it is appropriate f...

  2. 14 GHz bandwidth MSM photodiode AlGaAs/GaAs HEMT monolithic integrated optoelectronic receiver

    OpenAIRE

    Hurm, Volker; Ludwig, Manfred; Rosenzweig, Josef; Benz, Willi; Berroth, Manfred; Bosch, Roland; Bronner, Wolfgang; Hülsmann, Axel; Köhler, Klaus; Raynor, Brian; Schneider, Joachim

    1993-01-01

    A monolithic optoelectronic receiver consisting of an MSM photodiode and a two-stage amplifer has been fabricated using an enhancement/depletion 0.3 ?m recessed-gate AlGaAs/GaAs HEMT process. The band-width of 14.3 GHz implies suitability for transmission rates of up 20 Gbit/s. The transimpendance is 670 ? (into 50 ?) and the projected sensitivity is 16.4 dBm (BER = 10 -9).

  3. Bandwidth-control vs. doping-control Mott transition in the Hubbard model

    OpenAIRE

    Kim, Ki-seok

    2005-01-01

    We reinvestigate the bandwidth-control and doping-control Mott transitions (BCMT and DCMT) from a spin liquid Mott insulator to a Fermi liquid metal based on the slave-rotor representation of the Hubbard model,\\cite{Florens} where the Mott transitions are described by softening of bosonic collective excitations. We find that the nature of the insulating phase away from half filling is different from that of half filling in the respect that a charge density wave coexists with...

  4. A Literature Study on Dynamic Bandwidth Allocation Mechanisms for Tandem Communication Networks

    OpenAIRE

    CH. V. Raghavendran; G. Naga Satish; M.V. Rama SUNDARI; P. Suresh VARMA

    2014-01-01

    Modeling and performance prediction are becoming increasingly important issues in the design and operation of computer communications systems. In this paper a review is carried out on how Tandem queuing models with Dynamic Bandwidth Allocation have been applied so far into the performance evaluation of Communication Networks. Queuing network models with finite/infinite capacity buffers and blocking have been applied as more realistic models of systems with finite capac...

  5. Soliton Solutions for High-Bandwidth Optical Pulse Storage and Retrieval

    Science.gov (United States)

    Groves, Elizabeth

    Quantum-optical information processing in material systems requires on-demand manipulation and precision control techniques. Previous implementations of optical pulse control have mostly been limited to weak, narrowband probe fields, often using a modified form of Electromagnetically Induced Transparency (EIT). We propose optical pulse control in a contrasting regime with high-bandwidth optical pulses, enabling higher clock-rates and on-demand fast pulse switching. Our novel solutions exploit the coherent interaction between short, strong pulses and resonant media (such as a cloud of ultra-cold atoms) to store, manipulate, and retrieve high-bandwidth optical pulse information. The evolution equations that model such short pulse propagation are inherently nonlinear and they govern both amplitudes and phases of the propagating field and the dielectric medium. They cannot be modeled by population rate equations or simplified with steady-state assumptions. Nonlinear evolution equations do not yield solutions easily and using them to characterize the physics at hand typically requires complementary analytical and numerical approaches. We take both approaches here, using analytical methods and our own numerical integration code. For uniform and infinitely extended media we generate novel three-pulse soliton solutions: robust, nonlinear waves with the unique property of preserving their shape under interaction (or "collision"). This important property enables one high-bandwidth soliton to push another from one location in an atomic cloud to another, predictably and nondestructively. We then also probe the practical utility of our specialized infinite-extent solutions by numerically solving the same nonlinear evolution equations for a variety of initial pulse shapes and strengths. Our numerical simulations confirm that our novel soliton solutions provide appropriate control parameters, including pulse storage locations and pulse sequencing, even in finite media under non-idealized initial conditions. Combining our numerical and analytic results, we propose a scheme to manipulate high-bandwidth optical information and achieve on-demand, high-fidelity retrieval.

  6. Optical memory bandwidth and multiplexing capacity in the erbium telecommunication window

    CERN Document Server

    Dajczgewand, Julian; Böttger, Thomas; Louchet-Chauvet, Anne; Gouët, Jean-Louis Le; Chanelière, Thierry

    2014-01-01

    We study the bandwidth and multiplexing capacity of an erbium-doped optical memory for quantum storage purposes. We concentrate on the protocol ROSE (Revival of a Silenced Echo) because it has the largest potential multiplexing capacity. Our analysis is applicable to other protocols that involve strong optical excitation. We show that the memory performance is limited by instantaneous spectral diffusion and we describe how this effect can be minimised to achieve optimal performance.

  7. Investigation of Bandwidth Requirement of Smart Meter Network Using OPNET Modeler

    OpenAIRE

    Rahman, M.; Amanullah Mto

    2013-01-01

    Smart meter networks are the backbone for smart electrical distribution grid. Smart meter network requires the bidirectional communications medium and interoperability capability. As thousands of meters are interconnected in the smart meter network, it is vital to select an appropriate communication bandwidth to facilitate real-time two-way information flows and this will also allow further uptake of greenhouse-friendly technology options and enhance energy security. Optimized Network Enginee...

  8. A dynamic bandwidth allocator for virtual machines in a cloud environment

    OpenAIRE

    Amamou, Ahmed; Bourguiba, Manel; Haddadou, Kamel; Pujolle, Guy

    2012-01-01

    Cloud computing is an emergent paradigm that allows to customers to rent infrastructure, platforms and software as a service. With resource sharing and reuse through virtualization technology, cloud environments become even more effective and flexible. Nevertheless, networking within virtualized cloud still presents some challenges in performance and resource allocation. In this paper, we propose to integrate an SLA-based Dynamic Bandwidth Allocator (DBA) in a vitualized cloud environment. DB...

  9. Generation of indistinguishable and pure heralded single photons with tunable bandwidth

    CERN Document Server

    Shi, Xiaojuan; Hendrych, Martin; Torres, Juan P

    2007-01-01

    We describe a new scheme to fully control the joint spectrum of paired photons generated in spontaneous parametric down-conversion. We show the capability of this method to generate frequency-uncorrelated photon pairs that are pure and indistinguishable, and whose bandwidth can be readily tuned. Importantly, the scheme we propose here can be implemented in any nonlinear crystal and frequency band of interest.

  10. Bandwidth Enhancement of a Dual Band Planar Monopole Antenna Using Meandered Microstrip Feeding

    OpenAIRE

    Ahsan, M. R.; M. T. Islam; M. Habib Ullah; Misran, N

    2014-01-01

    A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (?r = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the...

  11. Potential Upgrade of the CMS Tracker Analog Readout Optical Links Using Bandwidth Efficient Digital Modulation

    OpenAIRE

    Dris, Stefanos; Foudas, Costas; Gill, Karl; Grabit, Robert; Ricci, Daniel; Troska, Jan; Vasey, Francois

    2010-01-01

    The potential application of advanced digital communication schemes in a future upgrade of the CMS Tracker readout optical links is currently being investigated at CERN. We show experimentally that multi-Gbit/s data rates are possible over the current 40 MSamples/s analog optical links by employing techniques similar to those used in ADSL. The concept involves using one or more digitally-modulated sinusoidal carriers in order to make efficient use of the available bandwidth.

  12. Feasibility of Using Bandwidth Efficient Modulation to Upgrade the CMS Tracker Readout Optical Links

    OpenAIRE

    Dris, Stefanos; Amaral, Luis; Gill, Karl; Grabit, Robert; Pacheco, Alberto; Ricci, Daniel; Troska, Jan; Vasey, Francois

    2010-01-01

    Plans to upgrade the LHC after approximately 10 years of operation are currently being considered at CERN. A tenfold increase in luminosity delivered to the experiments is envisaged in the so-called Super LHC (SLHC). This will undoubtedly give rise to significantly larger data volumes from the detectors, requiring faster data readout. The possibility of upgrading the CMS Tracker analog readout optical links using a bandwidth efficient digital modulation scheme for deployment...

  13. Tunable control of the bandwidth and frequency correlations of entangled photons

    OpenAIRE

    M. Hendrych; Micuda, M.; Torres, J.P.

    2006-01-01

    We demonstrate experimentally a new technique to control the bandwidth and the type of frequency correlations (correlation, anticorrelation, and even uncorrelation) of entangled photons generated by spontaneous parametric downconversion. The method is based on the control of the group velocities of the interacting waves. This technique can be applied in any nonlinear medium and frequency band of interest. It is also demonstrated that this technique helps enhance the quality ...

  14. Eight-channel reconfigurable microring filters with tunable frequency, extinction ratio and bandwidth

    OpenAIRE

    Shen, Hao; Khan, Maroof H.; Fan, Li; Zhao, Lin; Xuan, Yi; Ouyang, Jing; Varghese, Leo T.; Qi, Minghao

    2010-01-01

    We demonstrate an eight-channel reconfigurable optical filter on a silicon chip consisting of cascaded microring resonators and integrated compact heaters. With an embedded Mach-Zehnder (MZ) arm coupling to a microring resonator, the important parameters of a filter such as center frequency, extinction ratio and bandwidth can be controlled simultaneously for purposes of filtering, routing and spectral shaping, thus making our method potentially useful in dense wavelength div...

  15. Maximizing Utilization and Performance of Guaranteed-Bandwidth Long Fat Networks and Virtual Circuits

    OpenAIRE

    Freemon, D. Michael

    2014-01-01

    Like many big science projects, the Large Synoptic Survey Telescope (LSST) has multiple geographic locations among which large amounts of data must be transferred. One particular type of data, crosstalk-corrected images, must be moved from South America to North America under stringent deadline requirements. LSST is provisioning an international network with bandwidth guarantees to handle this traffic. In prior work, we re-examined TCP congestion control for this use case an...

  16. Ultra-narrow bandwidth tunable atomic filter based on electromagnetically induced transparency

    Science.gov (United States)

    Liu, Yang; Wang, Xiao-Xao; Kang, Zhi-Hui; Wang, Rong; Wang, Zeng-Bin; Gao, Jin-Yue

    2015-06-01

    We present an experimental study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency at 795?nm in rubidium vapor. The filter achieves a peak transmission of 8% and a linewidth of 15?MHz. The transmission peak can be tuned within the range of the Doppler linewidth. There is just one transmission peak, all other frequencies of light cannot pass through the filter.

  17. Dynamic Two-Tier Cell Structure for Bandwidth Reservation of Handoffs in Cellular Networks

    Science.gov (United States)

    Park, Jae Keun; Lee, Wan Yeon; Hong, Sung Je; Kim, Jong

    To satisfy both the bandwidth efficiency of low-speed mobile hosts (MHs) and seamless handoff of high-speed MHs in cellular networks, this paper proposes a reservation scheme which exploits a dynamic two-tier cell structure and the handoff probability. The dynamic two-tier cell structure determines the reservation and non-reservation zones according to the speed of MHs. The handoff probability is calculated using the moving speed and the direction of MHs.

  18. Anytime coding on the infinite bandwidth AWGN channel: A sequential semi-orthogonal optimal code

    OpenAIRE

    Sahai, Anant

    2006-01-01

    It is well known that orthogonal coding can be used to approach the Shannon capacity of the power-constrained AWGN channel without a bandwidth constraint. This correspondence describes a semi-orthogonal variation of pulse position modulation that is sequential in nature -- bits can be ``streamed across'' without having to buffer up blocks of bits at the transmitter. ML decoding results in an exponentially small probability of error as a function of tolerated receiver delay a...

  19. Bandwidth and resolution of super-resolution imaging with perforated solids

    OpenAIRE

    Zixian Liang; Jensen Li

    2011-01-01

    Recent experiments on acoustic superlens and hyperlens found anisotropic metamaterials constructed from periodic perforated solids can be used for super-resolution imaging. Here, we present a theoretical study on the operational bandwidth of these imaging devices using the emerging framework of transformation acoustics. Within the transformation approach, both the microstructural superlens and hyperlens can be discussed using the transfer matrix method on the same footing. We show that the ge...

  20. Circularly Polarized Double Layered Printed Hemispherical Helical Antenna with a Parasitic Wire for Bandwidth Enhancement

    Science.gov (United States)

    Latef, T. A.; Khamas, S. K.; Reza, Ahmed Wasif

    2014-07-01

    A helical antenna that is printed on a layered dielectric hemisphere has been studied when a parasitic helical wire is incorporated in the structure. Experimental and theoretical results demonstrate that the 3 dB axial ratio (AR) bandwidth can be enhanced by approximately 100% for optimized length and position of the parasitic wire. The analysis has been implemented using the method of moments (MoM), and good agreement has been achieved between computations and measurements.

  1. Bandwidth Enrichment for Micro-strip Patch Antenna Using Pendant Techniques

    OpenAIRE

    D. Bhattacharya, R. Prasanna

    2013-01-01

    A probe feed, slotted hexagonal patch antenna has been proposed. Bandwidth enhancement has been improved by suitably cutting slots into hexagonal patch.Proposed antenna is suitable for various telecoms, LAN, WiFi applications in ISM-band. It is demonstrated that the proposed antenna exhibits resonance in ISM-Band and a peak gain of 6dBi.The antenna structure is described and simulated results are presented.

  2. Design of bandwidth enhanced and multiband MIMO antennas using characteristic modes

    OpenAIRE

    Miers, Zachary; Li, Hui; Lau, Buon Kiong

    2013-01-01

    Recent work has shown that, with the help of the Theory of Characteristic Modes (TCM), minor modifications of the terminal chassis can facilitate the design of orthogonal MIMO antennas with viable bandwidth at frequencies below 1 GHz. Herein, a new framework is proposed to further exploit TCM to enhance the performance of the orthogonal MIMO antennas. By correlating the characteristic currents and near fields of modes with high modal significance in a given frequency band, a single feed may b...

  3. Multi-domain Information Exchange in a Bandwidth on Demand Tool

    OpenAIRE

    Giorgos Adam; Christos Bouras; Ioannis Kalligeros; Kostas Stamos; Giannis Zaoudis

    2014-01-01

    In this paper we describe the multi-domain information exchange aspects of the AutoBAHN tool, which is used for implementing a Bandwidth on Demand service as part of the GEANT project. This project was driven by the increasing demand for reliable and guaranteed data transportation for scientific purposes. In order to implement the process of information exchange in a multi-domain heterogeneous environment several design decisions have to take place, in order to balance and satisfy by the need...

  4. Efficient Schottky-like junction GaAs nanowire photodetector with 9?GHz modulation bandwidth with large active area

    Energy Technology Data Exchange (ETDEWEB)

    Seyedi, M. A., E-mail: seyedi@usc.edu; Yao, M.; O' Brien, J.; Wang, S. Y.; Dapkus, P. D. [Center for Energy Nanoscience, University of Southern California, Los Angeles, California 90089 (United States)

    2014-07-28

    Efficient, low capacitance density GaAs/Indium-Tin-Oxide Schottky-like junction photodetectors with a 50??m square active are fabricated for operation in the gigahertz range. Modulation bandwidth is experimentally measured up to 10?GHz at various applied reverse biases and optical intensities to explore the effects of photo-generated carrier screening on modulation bandwidth. Last, the bandwidth dependence on applied reverse bias and optical intensity is simulated as a means to quantify average carrier velocities in nanowire material systems.

  5. Demonstration of an X-Band Multilayer Yagi-Like Microstrip Patch Antenna With High Directivity and Large Bandwidth

    Science.gov (United States)

    Nessel, James A.; Zaman, Afroz; Lee, Richard Q.; Lambert, Kevin

    2005-01-01

    The feasibility of obtaining large bandwidth and high directivity from a multilayer Yagi-like microstrip patch antenna at 10 GHz is investigated. A measured 10-dB bandwidth of approximately 20 percent and directivity of approximately 11 dBi is demonstrated through the implementation of a vertically-stacked structure with three parasitic directors, above the driven patch, and a single reflector underneath the driven patch. Simulated and measured results are compared and show fairly close agreement. This antenna offers the advantages of large bandwidth, high directivity, and symmetrical broadside patterns, and could be applicable to satellite as well as terrestrial communications.

  6. Efficient Schottky-like junction GaAs nanowire photodetector with 9?GHz modulation bandwidth with large active area

    International Nuclear Information System (INIS)

    Efficient, low capacitance density GaAs/Indium-Tin-Oxide Schottky-like junction photodetectors with a 50??m square active are fabricated for operation in the gigahertz range. Modulation bandwidth is experimentally measured up to 10?GHz at various applied reverse biases and optical intensities to explore the effects of photo-generated carrier screening on modulation bandwidth. Last, the bandwidth dependence on applied reverse bias and optical intensity is simulated as a means to quantify average carrier velocities in nanowire material systems.

  7. Characterizing the In-Phase Reflection Bandwidth Theoretical Limit of Artificial Magnetic Conductors With a Transmission Line Model

    Science.gov (United States)

    Xie, Yunsong; Fan, Xin; Chen, Yunpeng; Wilson, Jeefrey D.; Simons, Rainee N.; Xiao, John Q.

    2013-01-01

    We validate through simulation and experiment that artificial magnetic conductors (AMC s) can be well characterized by a transmission line model. The theoretical bandwidth limit of the in-phase reflection can be expressed in terms of the effective RLC parameters from the surface patch and the properties of the substrate. It is found that the existence of effective inductive components will reduce the in-phase reflection bandwidth of the AMC. Furthermore, we propose design strategies to optimize AMC structures with an in-phase reflection bandwidth closer to the theoretical limit.

  8. Bandwidths of micro-twisted-pair cables and fusion-spliced SIMM-GRIN fiber

    International Nuclear Information System (INIS)

    The SLHC is designed to increase the luminosity of the LHC by a factor of 10. In the present ATLAS pixel detector, electrical signals between the pixel modules and the optical modules (opto-boards) are transmitted in ?1 m of micro-twisted-pair cables. The optical signals between the opto-boards and the off-detector optical modules are transmitted in fiber ribbons. Each fiber link consists of 8 m of rad-hard/low bandwidth SIMM fiber fusion spliced to 70 m of rad-tolerant/medium bandwidth GRIN fiber. We currently transmit optical signals at 80 Mb/s and expect to transmit signals at 1 Gb/s in the SLHC. For the SLHC optical link, we would like to take advantage of some of the design features of the present pixel optical links and the many years of R and D effort and production experience. If the present architecture can transmit signals at the higher speed required by the SLHC, the constraint of requiring no extra service space is automatically satisfied. We have measured the bandwidths of the transmission lines and our preliminary results indicate that the micro-twisted-pair cables can transmit signals up to ?1 Gb/s and the fusion-spliced fiber ribbon can transmit signals up to ?2 Gb/s

  9. A frequency and bandwidth tunable metamaterial absorber in x-band

    Science.gov (United States)

    Yuan, H.; Zhu, B. O.; Feng, Y.

    2015-05-01

    Smart control is an attracting and important function for modern electromagnetic wave absorber. This paper presents the design, fabrication, and measurement of a frequency and bandwidth tunable metamaterial absorber (MA) in X-band. The unit cell of the MA consists of a microstrip resonator loaded with the varactors. Simulation and measurement results show that by tuning the bias voltage on the varactors, the peak absorption frequency can be tuned by 0.44 GHz with the peak absorption greater than 95%. Field and circuit model analysis is conducted to reveal the working mode and predict the absorbing frequency. After that, by specially designing the bias circuit so as to adjust the bias voltage on neighboring unit cells separately, dual resonance and absorption peaks occur, and the overall absorption bandwidth can thus be tuned conveniently by controlling the difference of the two resonance frequencies. The center absorbing frequency can also be tuned. Simulation and experiment results show that the 75% absorption (-6 dB reflection) bandwidth can be tuned from 0.40 GHz to 0.74 GHz, which is a two-fold tuning range. This work is believed to improve the state-of-the-art smart metamaterial absorber.

  10. Design optimization of the distributed modal filtering rod fiber for increasing single mode bandwidth

    DEFF Research Database (Denmark)

    JØrgensen, Mette Marie; Petersen, Sidsel Rübner

    2012-01-01

    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 LMA fiber amplifiers having high pump absorption through a pump cladding that is decoupled from the outer fiber. However, achieving ultra low NA for single-mode (SM) guidance is challenging, and thus different design strategies must be applied to filter out higher order modes (HOMs). The novel distributed modal filtering (DMF) design presented here enables SM guidance, and previous results have shown a SM mode field diameter of 60 ?m operating in a 20 nm SM bandwidth. The DMF rod fiber has high index ring-shaped inclusions acting as resonators enabling SM guidance through modal filtering of HOMs. 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 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.

  11. Bandwidth Enhancement and Size Reduction of Microstrip Patch Antenna by Magnetoinductive Waveguide Loading

    Directory of Open Access Journals (Sweden)

    Swapna Devi

    2011-04-01

    Full Text Available A planar magnetoinductive (MI waveguide loaded rectangular microstrip patch antenna is presented and discussed. The MI waveguide consists of two planar metamaterial split squared ring resonators (SSRRs placed in between two microstrip lines. The backward wave propagation takes place through this structure. The rectangular microstrip patch antenna is magnetically coupled to the MI waveguide. The unloaded rectangular microstrip patch antenna resonates at 37.10 GHz. When loaded with planar MI waveguide, its resonant frequency is reduced to 9.38 GHz with the bandwidth and gain of 44% and 4.16 dBi respectively. In loaded condition, the dimension of antenna is 12.50 mm × 3.70 mm (0.390 ? × 0.115 ?. The appreciable bandwidth is achieved in such a small size antenna. The pass band frequency of MI waveguide is predicted by using the theoretical model of dispersion equation. The effective medium theory is used to verify the metamaterial characteristics of SSRR. The simulated results and theoretical calculations are also presented. The results show that the proposed method can be used to design compact and high bandwidth microstrip patch antennas.

  12. The effect of squeeze film constriction on bandwidth improvement in interferometric accelerometers

    Science.gov (United States)

    Perez, Maximillian A.; Shkel, Andrei M.

    2008-05-01

    This paper studies the effects of a constricted squeeze film on the performance of an optical microelectromechanical system accelerometer. Squeeze films are shown to extend the sensor frequency range (bandwidth) in accelerometers without decreasing the mechanical sensitivity by retarding the resonate response. By restricting the venting of a squeeze film, this preferential behavior is observed at lower frequencies than is expected for ideally vented accelerometers. Due to this effect, constricted squeeze films may be used to improve the bandwidth performance of devices of lower natural frequencies and higher inertial sensitivities. A model, extended from the existing squeeze film theory, is developed for the squeeze film formed between circular plates with generalized mixed boundary pressure conditions to describe the boundary flow resistance. These effects are experimentally observed in a parallel plate Fabry-Pérot interferometric accelerometer through frequency response characterization at mechanical resonance under pressure variation. The analytical results for the constricted squeeze film are used to predict the performance gains due to the frequency-dependent squeeze film parameters. These results are experimentally confirmed by demonstrating improved bandwidth performance due to the constricted squeeze film.

  13. Bandwidth-tunable narrowband rectangular optical filter based on stimulated Brillouin scattering in optical fiber.

    Science.gov (United States)

    Wei, Wei; Yi, Lilin; Jaouën, Yves; Hu, Weisheng

    2014-09-22

    We propose a rectangular optical filter based on stimulated Brillouin scattering (SBS) in optical fiber with bandwidth tuning from 50 MHz to 4 GHz at less than 15-MHz resolution. The rectangular shape of the filter is precisely achieved utilizing digital feedback control of the comb-like pump spectral lines. The passband ripple is suppressed to ~1 dB by mitigating the nonlinearity influences of the comb-like pump lines generated in electrical and optical components and fibers. Moreover a fiber with a single Brillouin peak is employed to further reduce the in-band ripple and the out-of-band SBS gain at the same time. Finally, we analyze the noise performance of the filter at different bandwidth cases and demonstrate the system performance of the proposed filter with 2.1-GHz bandwidth and 19-dB gain by amplifying a 2-GHz orthogonal frequency-division-multiplexing (OFDM) signal with quadrature-phase-shift-keying (QPSK) and 16-quadrature-amplitude-modulation (16-QAM) on each subscriber. PMID:25321794

  14. Bandwidth Enhancement of a U-Slot Patch Antenna Using Embedded HIS Structure

    Directory of Open Access Journals (Sweden)

    Pramod Kumar Singhal

    2012-10-01

    Full Text Available This paper proposes a new generation of antenna that applies metamaterial as a base construction. With the use of dual band high impedance surface (HIS structures, the bandwidth, return loss, and gain of U-slot patch antenna is improved at resonant frequencies 2.24 GHz and 5.8 GHz. The proposed new modified U-slot antenna has dual band impedance bandwidth from about 2.1886 to 2.27 GHz and 5.6149 to 7.2259 GHz. From the simulation result it was found that the upper frequency band of the proposed antenna lies in the band of $5.725 sim 5.825$ GHz regulated by IEEE 802.11a (upper band and can be used for bluetooth and WLAN applications. We perform this analysis on structures which composed of rectangular lattice patches periodic arrangements. All the dimensions and shapes of the unit cell geometry are optimized in order to get a broad bandwidth and high return loss. The lattice structure comprises of an array of $7 imes 5$ rectangular patches embedded in the substrate.

  15. A Novel Dynamic Bandwidth Allocation Model for Energy Efficient Multi-beam STICS Networks

    Directory of Open Access Journals (Sweden)

    Ramya Ranjan Choudhury

    2014-06-01

    Full Text Available Dynamic bandwidth allocation, keeping in view of energy efficiency is the utmost solutions to achieve flexible and efficient satellite based cellular networks. This would be helpful for communicating with anywhere and with anyone with global coverage. In this research article it is proposed that the assignment of bandwidth must be dynamic for this energy efficient mobile-satellite integrated system since user capacity demand is going to double by 2020. The model for such assignment is chosen in terms of obtaining energy efficiency thereby conducting measurement of interference. For this the quality of service on the basis of link control of threshold for a spectrum must be known. A pattern with frequency reuse ratio of 1 and 3 is selected consecutively keeping the fixed access satellites constant for the evaluation of energy efficient STICS systems. If the quality of link obtained from proposed model is maintained greater than blocking rate the frequency reuse would be unity. But in ideal case we can say that bandwidth requirement for quite large users can be sustained by implementing the model described in this paper

  16. An Improved Fitness Function and Mutation Operator for Metaheuristic Approaches to the Bandwidth Minimization Problem

    Science.gov (United States)

    Koohestani, Behrooz; Corne, David W.

    2009-04-01

    The Bandwidth Minimization Problem (BMP) is a graph layout problem which is known to be NP-complete. Since 1960, a considerable number of algorithms have been developed for addressing the BMP. At present, meta-heuristics (such as evolutionary algorithms and tabu search) are popular and successful approaches to the BMP. In such algorithms, the design of the fitness function (i.e. the metric that attempts to guide the search towards high-quality solutions) plays a key role in performance; the fitness function, along with the operators, induce the `search landscape', and careful attention to these issues may lead to landscapes that are more amenable to successful search. For example, rather than simply use the most obvious quality measure (in this case, the bandwidth itself), it is often helpful to design a more informative measure, indicating not only a solutions quality, but also encapsulating (for example) an indication of how distant this particular solution is from even better solutions. In this paper, a new fitness function and an associated new mutation operator are presented for BMP. These are incorporated within a simple Evolutionary Algorithm (EA), and evaluated on a set of 27 instances of the BMP (from the Harwell-Boeing sparse matrix collection). The results of this EA are compared with results obtained by using the standard fitness function (used in almost all previous researches on metaheuristics applied to the BMP). The results indicate clearly that the new fitness function and operator performed provide significantly superior results in the reduction of bandwidth.

  17. Multi-path Probabilistic Available Bandwidth Estimation through Bayesian Active Learning

    CERN Document Server

    Thouin, Frederic; Rabbat, Michael

    2010-01-01

    Knowing the largest rate at which data can be sent on an end-to-end path such that the egress rate is equal to the ingress rate with high probability can be very practical when choosing transmission rates in video streaming or selecting peers in peer-to-peer applications. We introduce probabilistic available bandwidth, which is defined in terms of ingress rates and egress rates of traffic on a path, rather than in terms of capacity and utilization of the constituent links of the path like the standard available bandwidth metric. In this paper, we describe a distributed algorithm, based on a probabilistic graphical model and Bayesian active learning, for simultaneously estimating the probabilistic available bandwidth of multiple paths through a network. Our procedure exploits the fact that each packet train provides information not only about the path it traverses, but also about any path that shares a link with the monitored path. Simulations and PlanetLab experiments indicate that this process can dramatical...

  18. Task Mapping and Bandwidth Reservation for Mixed Hard/Soft Fault-Tolerant Embedded Systems

    DEFF Research Database (Denmark)

    Saraswat, Prabhat Kumar; Pop, Paul

    2010-01-01

    In this paper we are interested in mixed hard/soft real-time fault-tolerant applications mapped on distributed heterogeneous architectures. We use the Earliest Deadline First (EDF) scheduling for the hard real-time tasks and the Constant Bandwidth Server (CBS) for the soft tasks. The bandwidth reserved for the servers determines the quality of service (QoS) for soft tasks. CBS enforces temporal isolation, such that soft task overruns do not affect the timing guarantees of hard tasks. Transient faults in hard tasks are tolerated using checkpointing with rollback recovery. We have proposed a Tabu Search-based approach for task mapping and CBS bandwidth reservation, such that the deadlines for the hard tasks are satisfied, even in the case of transient faults, and the QoS for the soft tasks is maximized. Researchers have used fixed execution time models, such as the worst-case execution times for hard tasks and average execution times for soft tasks. However, we show that by using stochastic execution times for soft tasks, significant improvements can be obtained. The proposed strategy has been evaluated using an extensive set of benchmarks.

  19. Bandwidth provisioning in infrastructure-based wireless networks employing directional antennas

    Energy Technology Data Exchange (ETDEWEB)

    Hasiviswanthan, Shiva [Los Alamos National Laboratory; Zhao, Bo [PENN STATE UNIV.; Vasudevan, Sudarshan [UNIV OF MASS AMHERST; Yrgaonkar, Bhuvan [PENN STATE UNIV.

    2009-01-01

    Motivated by the widespread proliferation of wireless networks employing directional antennas, we study the problem of provisioning bandwidth in such networks. Given a set of subscribers and one or more access points possessing directional antennas, we formalize the problem of orienting these antennas in two fundamental settings: (1) subscriber-centric, where the objective is to fairly allocate bandwidth among the subscribers and (2) provider-centric, where the objective is to maximize the revenue generated by satisfying the bandwidth requirements of subscribers. For both the problems, we first design algorithms for a network with only one access point working under the assumption that the number of antennas does not exceed the number of noninterfering channels. Using the well-regarded lexicographic max-min fair allocation as the objective for a subscriber-centric network, we present an optimum dynamic programming algorithm. For a provider-centric network, the allocation problem turns out to be NP-hard. We present a greedy heuristic based algorithm that guarantees almost half of the optimum revenue. We later enhance both these algorithms to operate in more general networks with multiple access points and no restrictions on the relative numbers of antennas and channels. A simulation-based evaluation using OPNET demonstrates the efficacy of our approaches and provides us further in insights into these problems.

  20. Extremely large bandwidth and ultralow-dispersion slow light in photonic crystal waveguides with magnetically controllability

    DEFF Research Database (Denmark)

    Pu, Shengli; Wang, Haotian

    2013-01-01

    A line-defect waveguide within a two-dimensional magnetic-fluid-based photonic crystal with 45o-rotated square lattice is presented to have excellent slow light properties. The bandwidth centered at $$ \\lambda_{0} $$ = 1,550 nm of our designed W1 waveguide is around 66 nm, which is very large than that of the conventional W1 waveguide as well as the corresponding optimized structures based on photonic crystal with triangular lattice. The obtained group velocity dispersion $$ \\beta_{2} $$ within the bandwidth is ultralow and varies from ?1,191$$ a/(2\\pi c^{2} ) $$ to 855$$ a/(2\\pi c^{2} ) $$ (a and c are the period of the lattice and the light speed in vacuum, respectively). Simultaneously, the normalized delay-bandwidth product is relatively large and almost invariant with magnetic field strength. It is indicated that using magnetic fluid as one of the constitutive materials of the photonic crystal structures can enable the magnetically fine tunability of the slow light in online mode. The concept and resultsof this work may give a guideline for studying and realizing tunable slow light based on the external-stimulus-responsive materials.

  1. Modern Fiber Optic Submarine Cable Telecommunication Systems Planning for Explosive Bandwidth Needs at Different Deployment Depths

    Directory of Open Access Journals (Sweden)

    Ahmed Nabih Zaki Rashed

    2012-10-01

    Full Text Available The explosive bandwidth needs, especially in the inter data center market, have pushed transmission data rates to 100 Gbit/sec and beyond. Current terrestrial fibers are inadequate for long haul, high bandwidth deployments. To solve these problems a new fiber is introduced for terrestrial high bandwidth deployments: different polymeric core fibers with enlarged effective area with a significant optical signal to noise ratio improvement over other conventional terrestrial single mode fibers. To ensure the new fiber may be deployed robustly a new coating structure was employed. A rigorous cable structure was then chosen for evaluation. Based on experimental data, both the deep ocean water temperature and pressure are tailored as functions of the water depth. As well as the product of the transmitted bit rate and the repeater spacing is processed over wide ranges of the affecting parameters. It is taken into account the estimation of the total cost of the submarine fiber cable system for transmission technique under considerations. The system capacity as well as the spectral losses, and the dispersion effects are parametrically investigated over wide range ranges of the set of affecting parameters {wavelength, ocean depth (and consequently the ocean pressure and temperature, and the chemical structure}.

  2. Electrical tweezer for highly parallelized electrorotation measurements over a wide frequency bandwidth.

    Science.gov (United States)

    Rohani, Ali; Varhue, Walter; Su, Yi-Hsuan; Swami, Nathan S

    2014-07-01

    Electrorotation (ROT) is a powerful tool for characterizing the dielectric properties of cells and bioparticles. However, its application has been somewhat limited by the need to mitigate disruptions to particle rotation by translation under positive DEP and by frictional interactions with the substrate. While these disruptions may be overcome by implementing particle positioning schemes or field cages, these methods restrict the frequency bandwidth to the negative DEP range and permit only single particle measurements within a limited spatial extent of the device geometry away from field nonuniformities. Herein, we present an electrical tweezer methodology based on a sequence of electrical signals, composed of negative DEP using 180-degree phase-shifted fields for trapping and levitation of the particles, followed by 90-degree phase-shifted fields over a wide frequency bandwidth for highly parallelized electrorotation measurements. Through field simulations of the rotating electrical field under this wave-sequence, we illustrate the enhanced spatial extent for electrorotation measurements, with no limitations to frequency bandwidth. We apply this methodology to characterize subtle modifications in morphology and electrophysiology of Cryptosporidium parvum with varying degrees of heat treatment, in terms of shifts in the electrorotation spectra over the 0.05-40 MHz region. Given the single particle sensitivity and the ability for highly parallelized electrorotation measurements, we envision its application toward characterizing heterogeneous subpopulations of microbial and stem cells. PMID:24668830

  3. MHBCDA: Mobility and Heterogeneity aware Bandwidth Efficient Cluster based Data Aggregation for Wireless Sensor Network

    DEFF Research Database (Denmark)

    Dnyaneshwar, Mantri; Prasad, Neeli R.

    2013-01-01

    Wireless Sensor Network (WSN) offers a variety of novel applications for mobile targets. It generates the large amount of redundant sensing data. The data aggregation techniques are extensively used to reduce the energy consumption and increase the network lifetime, although it has the side effect of reduced reliability. In the mobile environment, it is necessary to consider the techniques which minimize the communication cost with efficient bandwidth utilization by decreasing the packet count reached at the sink. This paper proposes the mobility and heterogeneity aware bandwidth efficient Cluster-based Data Aggregation (MHBCDA) algorithm for the randomly distributed nodes. It considers the mobile sink based packet aggregation for the heterogeneous WSN. It uses predefined region for the aggregation at cluster head to minimize computation and communication cost. The MHBCDA is energy and bandwidth efficient. It exploits correlation of data packets generated by varying the packet generation rate. It prevents transmission of redundant data packets by improving energy consumption by 4.11% and prolongs the network life by 34.45% as compared with state-of-the-art solutions.

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

    Science.gov (United States)

    Aelterman, Jan; Naeyaert, Maarten; Gutierrez, Shandra; Luong, Hiep; Goossens, Bart; Pižurica, Aleksandra; Philips, Wilfried

    2014-01-01

    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. PMID:24915203

  5. Signal Processing Algorithm for Controlling Dynamic Bandwidth of Fiber Optic Accelerometer

    International Nuclear Information System (INIS)

    This paper presents a signal processing algorithm to control the dynamic bandwidth of a single-degree-of-freedom (SDF) dynamic sensor system. An accelerometer is a representative SDF sensor system. In this paper, a moire-fringe-based fiber optic accelerometer is newly used for the test of the algorithm. The accelerometer is composed of one mass, one damper and one spring as a SDF dynamic system. In order to increase the dynamic bandwidth of the accelerometer, it is needed to increase the spring constant or decrease the mass. However, there are mechanical difficulties of this adjustment. Therefore, the presented signal processing algorithm is very effective to overcome the difficulties because it is just adjustment in the signal processing software. In this paper, the novel fiber optic accelerometer is introduced shortly, and the algorithm is applied to the fiber optic accelerometer to control its natural frequency and damping ratio. Several simulations and experiments are carried out to prove the performance of the algorithm. As a result, it is shown that the presented signal processing algorithm is a good way to broaden the dynamic bandwidth of the fiber optic accelerometer

  6. The effect of squeeze film constriction on bandwidth improvement in interferometric accelerometers

    International Nuclear Information System (INIS)

    This paper studies the effects of a constricted squeeze film on the performance of an optical microelectromechanical system accelerometer. Squeeze films are shown to extend the sensor frequency range (bandwidth) in accelerometers without decreasing the mechanical sensitivity by retarding the resonate response. By restricting the venting of a squeeze film, this preferential behavior is observed at lower frequencies than is expected for ideally vented accelerometers. Due to this effect, constricted squeeze films may be used to improve the bandwidth performance of devices of lower natural frequencies and higher inertial sensitivities. A model, extended from the existing squeeze film theory, is developed for the squeeze film formed between circular plates with generalized mixed boundary pressure conditions to describe the boundary flow resistance. These effects are experimentally observed in a parallel plate Fabry–Pérot interferometric accelerometer through frequency response characterization at mechanical resonance under pressure variation. The analytical results for the constricted squeeze film are used to predict the performance gains due to the frequency-dependent squeeze film parameters. These results are experimentally confirmed by demonstrating improved bandwidth performance due to the constricted squeeze film

  7. Metamaterial composite bandpass filter with an ultra-broadband rejection bandwidth of up to 240 terahertz

    DEFF Research Database (Denmark)

    Strikwerda, Andrew; Zalkovskij, Maksim

    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, such as photoconductive antennas and difference frequency generation. The composite structure shown here expands the usable bandwidth to exceed that of current THz sources. To highlight the applicability of this combination, we demonstrate a series of bandpass filters with only a single pass band, with a central 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 equations—and discuss their scaling laws—which detail the f and full width at half max (?f) of the pass band, as well as the required geometric dimensions for their fabrication using standard UV photolithography and easily achievable fabrication linewidths. With these equations, the geometric parameters and ?f for a desired frequency can be quickly calculated. Using these bandpass filters as a proof of principle, we believe that this metamaterial composite provides the key for ultra-broadband metamaterial design.

  8. Metamaterial composite bandpass filter with an ultra-broadband rejection bandwidth of up to 240 terahertz

    Science.gov (United States)

    Strikwerda, Andrew C.; Zalkovskij, Maksim; Lund Lorenzen, Dennis; Krabbe, Alexander; Lavrinenko, Andrei V.; Uhd Jepsen, Peter

    2014-05-01

    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, such as photoconductive antennas and difference frequency generation. The composite structure shown here expands the usable bandwidth to exceed that of current THz sources. To highlight the applicability of this combination, we demonstrate a series of bandpass filters with only a single pass band, with a central frequency (f0) 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 equations—and discuss their scaling laws—which detail the f0 and full width at half max (?f) of the pass band, as well as the required geometric dimensions for their fabrication using standard UV photolithography and easily achievable fabrication linewidths. With these equations, the geometric parameters and ?f for a desired frequency can be quickly calculated. Using these bandpass filters as a proof of principle, we believe that this metamaterial composite provides the key for ultra-broadband metamaterial design.

  9. A multiprocessor computer simulation model employing a feedback scheduler/allocator for memory space and bandwidth matching and TMR processing

    Science.gov (United States)

    Bradley, D. B.; Irwin, J. D.

    1974-01-01

    A computer simulation model for a multiprocessor computer is developed that is useful for studying the problem of matching multiprocessor's memory space, memory bandwidth and numbers and speeds of processors with aggregate job set characteristics. The model assumes an input work load of a set of recurrent jobs. The model includes a feedback scheduler/allocator which attempts to improve system performance through higher memory bandwidth utilization by matching individual job requirements for space and bandwidth with space availability and estimates of bandwidth availability at the times of memory allocation. The simulation model includes provisions for specifying precedence relations among the jobs in a job set, and provisions for specifying precedence execution of TMR (Triple Modular Redundant and SIMPLEX (non redundant) jobs.

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

    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...

  11. Control of delay-bandwidth product in slow-light photonic crystal waveguides with asymmetric microfluidic infiltration

    International Nuclear Information System (INIS)

    In this work, we report on the optofluidic tuning of the delay bandwidth product of a slow-light photonic crystal waveguide. The proposed tuning method is obtained by infiltrating the central two rows of the W09 waveguide. These infiltrated rows consist of holes that are infiltrated asymmetrically by different liquids with different refractive indices. The simulation results show that by changing the refractive index of the infiltrated liquids, we can achieve a very flat band corresponding with low group velocity and dispersion. It is found that the values of the bandwidth and group index—the bandwidth product of the proposed waveguide—can be improved by changing the refractive index of the infiltrated liquid. This approach allows us to control the group velocity, dispersion and delay bandwidth product of the slow-light photonic crystal waveguide by choosing a suitable refractive index of the two infiltrated liquids. (paper)

  12. An Experimental Study of the Printed-Circuit Elliptic Dipole Antenna with 1.5-16 GHz Bandwidth

    OpenAIRE

    Wang, Chia-wei; Lee, Chun-chi; Yang, Cheng-da; Huang, Hsin-sheng

    2008-01-01

    Printed-circuit board (PCB) elliptic antennas with useful bandwidth exceeding 10:1 ratio are suitable for wideband radar, wireless ultra wideband (UWB) and other wireless communication applications. We present wideband PCB elliptic dipole antennas which are capable of achieving the bandwidth requirements for all the applications. A set of elliptic dipole antennas with varying eccentricities have been fabricated for demonstration. We find one specific size (specific eccentricity) dipole that c...

  13. Bandwidth measurements and capacity exploitation in Gigabit Passive Optical Networks2014 Fotonica AEIT Italian Conference on Photonics Technologies

    OpenAIRE

    Mellia, Marco

    2014-01-01

    We report an experimental investigation on the measurement of the available bandwidth for users in Gigabit Passive Optical Networks (GPON) and the limitations caused by the Internet protocols. We point out that the huge capacity offered by the GPON highlights the enormous differences that can be showed among the available and actually exploitable bandwidth in the case of TCP. In this ultrabroadband environment we also investigated on use of the UDP and of the multisession TCP. A correlation i...

  14. Biases caused by the instrument bandwidth and beam width on simulated brightness temperature measurements from scanning microwave radiometers

    Directory of Open Access Journals (Sweden)

    V. Meunier

    2013-05-01

    Full Text Available More so than the traditional fixed radiometers, the scanning radiometer requires a careful design to ensure high quality measurements. Here the impact of the radiometer characteristics (e.g., antenna beam width and receiver bandwidth and atmospheric propagation (e.g. curvature of the Earth and vertical gradient of refractive index on scanning radiometer measurements are presented. A forward radiative transfer model that includes all these effects to represent the instrument measurements is used to estimate the biases. These biases are estimated using differences between the measurement with and without these characteristics for three commonly used frequency bands: K, V and W-band. The receiver channel bandwidth errors are less important in K-band and W-band. Thus, the use of a wider bandwidth to improve detection at low signal-to-noise conditions is acceptable at these frequencies. The biases caused by omitting the antenna beam width in measurement simulations are larger than those caused by omitting the receiver bandwidth, except for V-band where the bandwidth may be more important in the vicinity of absorption peaks. Using simple regression algorithms, the effects of the bandwidth and beam width biases in liquid water path, integrated water vapour, and temperature are also examined. The largest errors in liquid water path and integrated water vapour are associated with the beam width errors.

  15. Self-seeding scheme with gas monochromator for narrow-bandwidth soft X-ray FELs

    International Nuclear Information System (INIS)

    Self-seeding schemes, consisting of two undulators with a monochromator in between, aim at reducing the bandwidth of SASE X-ray FELs. We recently proposed to use a new method of monochromatization exploiting a single crystal in Bragg transmission geometry for self-seeding in the hard X-ray range. Here we consider a possible extension of this method to the soft X-ray range using a cell filled with resonantly absorbing gas as monochromator. The transmittance spectrum in the gas exhibits an absorbing resonance with narrow bandwidth. Then, similarly to the hard X-ray case, the temporal waveform of the transmitted radiation pulse is characterized by a long monochromatic wake. In fact, the FEL pulse forces the gas atoms to oscillate in a way consistent with a forward-propagating, monochromatic radiation beam. The radiation power within this wake is much larger than the equivalent shot noise power in the electron bunch. Further on, the monochromatic wake of the radiation pulse is combined with the delayed electron bunch and amplified in the second undulator. The proposed setup is extremely simple, and composed of as few as two simple elements. These are the gas cell, to be filled with noble gas, and a short magnetic chicane. The installation of the magnetic chicane does not perturb the undulator focusing system and does not interfere with the baseline mode of operation. In this paper we assess the features of gas monochromator based on the use of He and Ne.We analyze the processes in the monochromator gas cell and outside it, touching upon the performance of the differential pumping system as well. We study the feasibility of using the proposed self-seeding technique to generate narrow bandwidth soft X-ray radiation in the LCLS-II soft X-ray beam line. We present conceptual design, technical implementation and expected performances of the gas monochromator self-seeding scheme. (orig.)

  16. 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.

  17. A Quality of Service Strategy to Optimize Bandwidth Utilization in Mobile Networks

    OpenAIRE

    Arockiam, L.; Calduwel Newton, P.; Isac Gnanaraj, J.

    2010-01-01

    The mobile network that supports network mobility is an emerging technology. It is also referred as NEMO (NEtwork MObility). It is more appropriate for mobile platforms such as car, bus, train, air plane, etc. It is a great challenge to provide Quality of Service (QoS) in NEMO. QoS is a set of service requirements to be met by the network. There are various parameters by which QoS is provided. This paper concentrates on providing optimum bandwidth for data traffic. The objective of this paper...

  18. 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.

  19. Nonclassical correlations between terahertz-bandwidth photons mediated by rotational quanta in hydrogen molecules.

    Science.gov (United States)

    Bustard, Philip J; Erskine, Jennifer; England, Duncan G; Nunn, Josh; Hockett, Paul; Lausten, Rune; Spanner, Michael; Sussman, Benjamin J

    2015-03-15

    Quantum photonics offers much promise for the development of new technologies. The ability to control the interaction of light and matter at the level of single quantum excitations is a prerequisite for the construction of potentially powerful devices. Here we use the rotational levels of a room temperature ensemble of hydrogen molecules to couple two distinct optical modes at the single photon level using femtosecond pulses with 2 THz bandwidth. We observe photon correlations that violate a Cauchy-Schwarz inequality, thereby verifying the creation of a nonclassical state. This work demonstrates the rich potential of molecules for use in ultrafast quantum photonic devices. PMID:25768147

  20. Low-bandwidth control scheme for an oscillator-stabilized Josephson qubit

    Science.gov (United States)

    Koch, R. H.; Rozen, J. R.; Keefe, G. A.; Milliken, F. M.; Tsuei, C. C.; Kirtley, J. R.; Divincenzo, D. P.

    2005-09-01

    We introduce a Josephson junction circuit for which quantum operations are realized by low-bandwidth, nearly adiabatic magnetic-flux pulses. Coupling to the fundamental mode of a superconducting transmission line permits a stabilization of the rotation angle of the quantum operation against flux noise. A complete scheme for one-qubit rotations, and high-visibility Ramsey-fringe oscillations, is given. We show that high visibility depends on passing through a portal in the space of applied fluxes, where the width of the portal is proportional to the ramp-up rate of the flux pulse.

  1. An interleaver with tunable bandwidth ratio based on microring resonator coupled Mach-Zehnder interferometer

    Science.gov (United States)

    Xu, Chi; Zhang, Yundong; Zhang, Xuenan; Wang, Kaiyang; Wu, Yongfeng; Zhai, Xianxin; Yuan, Ping

    2015-03-01

    A fundamental structure of a passive interleaver based on microring resonator coupled Mach-Zehnder interferometer is proposed in this paper. The most conspicuous advantage is the simplicity, compactness of the structure and the flatness of the passband top. Then we propose two methods of realizing a bandwidth tunability in this structure. A further analysis shows that both methods have their own strengths. We expect the compact and flexible interleaver can provide some potential and important implications for upgrading a hybrid Dense Wavelength Division Multiplexing (DWDM) system.

  2. Interfacing GHz-bandwidth heralded single photons with a warm vapour Raman memory

    Science.gov (United States)

    Michelberger, P. S.; Champion, T. F. M.; Sprague, M. R.; Kaczmarek, K. T.; Barbieri, M.; Jin, X. M.; England, D. G.; Kolthammer, W. S.; Saunders, D. J.; Nunn, J.; Walmsley, I. A.

    2015-04-01

    Broadband quantum memories, used as temporal multiplexers, are a key component in photonic quantum information processing, as they make repeat-until-success strategies scalable. We demonstrate a prototype system, operating on-demand, by interfacing a warm vapour, high time-bandwidth-product Raman memory with a travelling wave spontaneous parametric down-conversion source. We store single photons and observe a clear influence of the input photon statistics on the retrieved light, which we find currently to be limited by noise. We develop a theoretical model that identifies four-wave mixing as the sole important noise source and point towards practical solutions for noise-free operation.

  3. Bandwidth and Resource Allocation for Full Implementation of e-Election in Nigeria

    OpenAIRE

    Nsed A.Akonjom; Julie C.Ogbulezie

    2014-01-01

    Voting is an act of democracy. Citizens are given the opportunity to voice their opinions by voting. Involving technology will enhance the process by ensuring that every citizen irrespective of his/her abilities or disabilities can exercise such rights. This research work seeks to bring to fore the full benefits of implementing complete e-Election in Nigeria and also using an M/G/S based simulation software predicted the bandwidth as well as resource allocation for an effective conduct of e-v...

  4. 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 measurement. An additional advantage over prior art is that, computationally, the DCF requires significantly fewer real-time calculations than a Kalman filter formulation. There are essentially two reasons for this: the DCF state is not augmented with angular rate, and measurement updates occur at the slower gyro rate instead of the faster ARS sampling rate. Finally, the DCF has a simple and compelling architecture. The DCF is exactly equivalent to flying two identical attitude observers, one at low rate and one at high rate. These attitude observers are exactly of the form currently flown on typical three-axis spacecraft.

  5. Space-bandwidth scaling for wide field-of-view imaging.

    Science.gov (United States)

    Milojkovic, Predrag; Mait, Joseph N

    2012-02-01

    We examine the space-bandwidth product of wide field-of-view imaging systems as the systems scale in size. Our analysis is based on one conducted to examine the behavior of a plano-convex lens imaging onto a flat focal geometry. We extend this to consider systems with monocentric lenses and curved focal geometries. As a means to understand system cost, and not just performance, we also assess the volume and mass associated with these systems. Our analysis indicates monocentric lenses imaging onto a curved detector outperform other systems for the same design constraints but do so at a cost in lens weight. PMID:22307128

  6. Managing Supply and Demand of Bandwidth in Peer-to-Peer Communities:

    OpenAIRE

    Meulpolder, M.

    2011-01-01

    On today's Internet, millions of people participate in peer-to-peer communities where they share content such as audio and video files. Contrary to websites such as Youtube, which rely on large and expensive computer servers to store and deliver all of their content, peer-to-peer communities rely on storage and delivery by the PCs of the users themselves. Because of this, a peer-to-peer community can only be successful if there are enough users willing to provide content and bandwidth to othe...

  7. An Adaptive Weight Calculation based Bandwidth Allocation Scheme for IEEE 802.16 Networks

    OpenAIRE

    Akash Deep; Ks, Kahlon

    2014-01-01

    WiMAX standard also known as IEEE 802.16 is a wireless MAN standard driven by WiMAX Forum. WiMAX forum defines specification for QoS provisioning for manufacturing of WiMAX equipment by different vendors but the amount of bandwidth allocated to specific service in WIMAX is still an open issue. A number of algorithms have been presented to satisfy the diverse QoS requirements for traffic in WiMAX networks. The focus of all these algorithms is towards real time traffic. Non real time traffic li...

  8. Multi-path Probabilistic Available Bandwidth Estimation through Bayesian Active Learning

    OpenAIRE

    Thouin, Frederic; Coates, Mark; Rabbat, Michael

    2010-01-01

    Knowing the largest rate at which data can be sent on an end-to-end path such that the egress rate is equal to the ingress rate with high probability can be very practical when choosing transmission rates in video streaming or selecting peers in peer-to-peer applications. We introduce probabilistic available bandwidth, which is defined in terms of ingress rates and egress rates of traffic on a path, rather than in terms of capacity and utilization of the constituent links of...

  9. Optimization of Gain, Impedance, and Bandwidth of Yagi-Uda Array Using Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    B. S. Sohi

    2008-05-01

    Full Text Available Particle swarm optimization (PSO is a new, high-performance evolutionary technique, which has recently been used for optimization problems in antennas and electromagnetics. It is a global optimization technique-like genetic algorithm (GA but has less computational cost compared to GA. In this paper, PSO has been used to optimize the gain, impedance, and bandwidth of Yagi-Uda array. To evaluate the performance of designs, a method of moments code NEC2 has been used. The results are comparable to those obtained using GA.

  10. JPL 2-to-the-20th-power channel 300 MHz bandwidth digital spectrum analyzer

    Science.gov (United States)

    Morris, G. A., Jr.; Wilck, H. C.

    1978-01-01

    A million (two to the 20th power) channel, 300 MHz bandwidth, digital spectrum analyzer was considered. The design, fabrication, and maintenance philosophy of the modular, pipelined, fast fourier transform (FFT) hardware are described. The spectrum analyzer will be used to examine the region from 1.4 GHz to 26 GHz for radio frequency interference which may be harmful to present and future tracking missions of the Deep Space Network. The design has application to the search for extraterrestrial intelligence signals and radio science phenomena.

  11. High-bandwidth transfer of phase stability through a fiber frequency comb

    CERN Document Server

    Scharnhorst, Nils; Hannig, Stephan; Jakobsen, Kornelius; Kramer, Johannes; Leroux, Ian D; Schmidt, Piet O

    2015-01-01

    We demonstrate phase locking of a 729 nm diode laser to a 1542 nm master laser via an erbium-doped-fiber frequency comb. Thanks to a transfer-oscillator feedforward scheme which suppresses the effect of comb noise in an unprecedented 1.8 MHz bandwidth, the phase lock requires no pre-stabilization of the slave diode laser. We illustrate the performance of the system by carrying out coherent manipulations of a trapped calcium ion with a fidelity in excess of 99% even at few-microsecond timescales.

  12. Fiber optics sensor for sub-nanometric displacement and wide bandwidth systems

    OpenAIRE

    Perret, Luc; Chassagne, Luc; Topsu, Suat; Ruaux, Pascal; Cagneau, Barthe?lemy; Alayli, Yasser

    2010-01-01

    In this paper, we report fiber optics sensor with sub-nanometric resolution and wide bandwidth. It relies on an increase of the reception fibers number and on low-noise electronics. Moreover, a reference channel has been implemented using a semi-reflective plate to eliminate the source fluctuations and the fiber sensor was isolated to limit external influence of temperature and pressure. Thus we achieve both a sub-nanometric resolution on a 400 ms integration time and a long-term drift as low...

  13. Printed Wide-Slot Antenna Design with Bandwidth and Gain Enhancement on Low-Cost Substrate

    OpenAIRE

    Samsuzzaman, M.; Islam, M. T.; Mandeep, J. S.; Misran, N.

    2014-01-01

    This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gai...

  14. Wave groupiness and spectral bandwidth as relevant parameters for the performance assessment of wave energy converters

    OpenAIRE

    Saulnier, Jean-baptiste; Clement, Alain; Falcao, Antonio F. O.; Pontes, Teresa; Prevosto, Marc; Ricci, Pierpaolo

    2011-01-01

    To date the estimation of long-term wave energy production at a given deployment site has commonly been limited to a consideration of the significant wave height H, and mean energy period T. This paper addresses the sensitivity of power production from wave energy converters to the wave groupiness and spectral bandwidth of sea states. Linear and non-linear systems are implemented to simulate the response of converters equipped with realistic power take-off devices in real sea states. It is sh...

  15. Note: Seesaw actuation of atomic force microscope probes for improved imaging bandwidth and displacement range

    International Nuclear Information System (INIS)

    The authors describe a method of actuation for atomic force microscope (AFM) probes to improve imaging speed and displacement range simultaneously. Unlike conventional piezoelectric tube actuation, the proposed method involves a lever and fulcrum ''seesaw'' like actuation mechanism that uses a small, fast piezoelectric transducer. The lever arm of the seesaw mechanism increases the apparent displacement range by an adjustable gain factor, overcoming the standard tradeoff between imaging speed and displacement range. Experimental characterization of a cantilever holder implementing the method is provided together with comparative line scans obtained with contact mode imaging. An imaging bandwidth of 30 kHz in air with the current setup was demonstrated.

  16. Energy-bandwidth trade-off in all-optical photonic crystal microcavity switches

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Kristensen, Philip TrØst

    2011-01-01

    The performance of all-optical switches is a compromise between the achievable bandwidth of the switched signal and the energy requirement of the switching operation. In this work we consider a system consisting of a photonic crystal cavity coupled to two input and two output waveguides. As a specific example of a switching application, we investigate the demultiplexing of an optical time division multiplexed signal. To quantify the energy-bandwidth trade-off, we introduce a figure of merit for the detection of the demultiplexed signal. In such investigations it is crucial to consider patterning effects, which occur on time scales that are longer than the bit period. Our analysis is based on a coupled mode theory, which allows for an extensive investigation of the influence of the system parameters on the switching dynamics. The analysis is shown to provide new insights into the ultrafast dynamics of the switching operation, and the results show optimum parameter ranges that may serve as design guidelines in device fabrication. © 2011 Optical Society of America.

  17. Theoretical study of amplified spontaneous emission intensity and bandwidth reduction in polymer

    Science.gov (United States)

    Hariri, A.; Sarikhani, S.

    2015-04-01

    Amplified spontaneous emission (ASE), including intensity and bandwidth, in a typical example of BuEH-PPV is calculated. For this purpose, the intensity rate equation is used to explain the reported experimental measurements of a BuEH-PPV sample pumped at different pump intensities from Ip = 0.61 MW/cm2 to 5.2 MW/cm2. Both homogeneously and inhomogeneously broadened transition lines along with a model based on the geometrically dependent gain coefficient (GDGC) are examined and it is confirmed that for the reported measurements the homogeneously broadened line is responsible for the light–matter interaction. The calculation explains the frequency spectrum of the ASE output intensity extracted from the sample at different pump intensities, unsaturated and saturated gain coefficients, and ASE bandwidth reduction along the propagation direction. Both analytical and numerical calculations for verifying the GDGC model are presented in this paper. Although the introduced model has shown its potential for explaining the ASE behavior in a specific sample it can be universally used for the ASE study in different active media.

  18. Design of RFID Cloud Services in a Low Bandwidth Network Environment

    Directory of Open Access Journals (Sweden)

    John P.T. Mo

    2011-02-01

    Full Text Available The use of Information and Communication Technologies has significantly improved the efficiency of modern supply chains. Existing IT architecture is too rigid to allow new technologies such as RFID technologies to be implemented. With the aid of virtualisation and integrated with cloud services, infrastructure hardware and network devices can be consolidated into a physical device, reducing the cost of ownership. However, for such cloud services model to work correctly, a high speed network is required between each site and the cloud service provider. This poses huge challenges for real?time system such as RFID?enabled supply chains. Since modern supply chains operate on a global platform, it is almost impossible to assure availability of high speed networks across the global supply chain. This paper proposes two solutions to supplement the virtualisation and cloud services model. A sub?cloud services solution, where each service is distributed across multiple hosts across different countries and regions is proposed to enhance accessibility to higher bandwidth networks. The second solution is the Queued Burst Device Compression system incorporates a compression service that compresses RFID data sets into much smaller packages. This solution is proved to work by a multiple?in?single?out queuing model and is suitable for low bandwidth networks such as GPRS and 3G wireless environmenst.

  19. BHCDA: Bandwidth Efficient Heterogeneity aware Cluster based Data Aggregation for Wireless Sensor Network

    DEFF Research Database (Denmark)

    Dnyaneshwar, Mantri; Prasad, Neeli R.

    2013-01-01

    The fundamental challenge in the design of Wireless sensor Network (WSNs) is proper utilization of resources which are scare. One of the critical challenges is to maximize the bandwidth utilization in data gathering from sensor nodes and forward to sink. The main design objective of this paper is to utilize the available bandwidth efficiently with reduced packet delivery ratio and throughput. BHCDA presents the solution for effective data gathering with in-network aggregation. It considers the network with heterogeneous nodes in terms of energy and mobile sink to aggregate the data packets. It embodies the optimal approach by Intra and inter-cluster aggregation on the randomly distributed nodes with variable data generation rate while routing data to sink. It uses the correlation of data within the packet for applying the aggregation function on data generated by nodes. BHCDA shows significant improvement in packet delivery ratio (67.66% & 19.62%) and throughput (37.01 % & 17.16%) as compared with the state-of-the-art solutions (TTCDA and EECDA).

  20. Scintillators for fiber optics: system sensitivity and bandwidth as a function of fiber length

    International Nuclear Information System (INIS)

    Scintillators have been employed for several years as ionizing radiation-to-light converters in plasma diagnostic experiments that utilize fiber optics. Until recently, nanosecond and subnanosecond scintillators were available only in the near ultraviolet. However, the bandwidth and transmission properties of fiber optics both strongly favor operation at longer wavelengths. More recently, nanosecond and subnanosecond scintillators with emission peaks around 480 nm have been reported. A time-resolved plasma-imaging experiment using one of these scintillators and 100 channels of graded-index fiber, each 500 m long, has been successfully tested on a nuclear event at the Nevada Test Site. During the past year we have developed several new scintillator systems with emission wavelengths more compatible with fiber optics and with response times in the nanosecond and subnanosecond time region. One scintillator, based on Kodak dye 14567 (DCM), has an emission maximum at 650 nm and a response time (FWHM) of 1.2 ns. Experimental data on system sensitivity and bandwidth versus fiber length are presented for three fluor-fiber systems. Data on fluor formulation, response time, and linearity-of-response are given, and a model for scintillator nonlinearity, based on solvent, radiation-induced, transient absorption, is presented

  1. Eight-channel reconfigurable microring filters with tunable frequency, extinction ratio and bandwidth.

    Science.gov (United States)

    Shen, Hao; Khan, Maroof H; Fan, Li; Zhao, Lin; Xuan, Yi; Ouyang, Jing; Varghese, Leo T; Qi, Minghao

    2010-08-16

    We demonstrate an eight-channel reconfigurable optical filter on a silicon chip. It consists of cascaded microring resonators and integrated compact heaters. With an embedded Mach-Zehnder (MZ) arm coupling to a microring resonator, the important parameters of a filter such as center frequency, extinction ratio and bandwidth can be controlled simultaneously for purposes of filtering, routing and spectral shaping. Thus our device could potentially be useful in dense wavelength division multiplexing (DWDM) and radio frequency arbitrary waveform generation (RFAWG). Multichannel filter response was successfully tuned to match the International Telecommunication Unit (ITU) grid with 50, 100 and 200 GHz in channel spacing. Programmable channel selectivity was demonstrated by heating the MZ arm, and continuous adjustment of through-port extinction ratio from 0 dB to 27 dB was achieved. Meanwhile, the 3 dB bandwidth in the drop port changed from 0.12 nm to 0.16 nm. The device had an ultra-compact footprint (1200 microm x 100 microm) excluding the metal leads and contact pads, making it suitable for large scale integration. PMID:20721194

  2. Eight-channel reconfigurable microring filters with tunable frequency, extinction ratio and bandwidth

    CERN Document Server

    Shen, Hao; Fan, Li; Zhao, Lin; Xuan, Yi; Ouyang, Jing; Varghese, Leo T; Qi, Minghao

    2010-01-01

    We demonstrate an eight-channel reconfigurable optical filter on a silicon chip consisting of cascaded microring resonators and integrated compact heaters. With an embedded Mach-Zehnder (MZ) arm coupling to a microring resonator, the important parameters of a filter such as center frequency, extinction ratio and bandwidth can be controlled simultaneously for purposes of filtering, routing and spectral shaping, thus making our method potentially useful in dense wavelength division multiplexing (DWDM) and radio frequency arbitrary waveform generation (RFAWG). Multichannel filter response was successfully tuned to match the International Telecommunication Unit (ITU) grid with 50, 100 and 200GHz in channel spacing. Programmable channel selectivity was demonstrated by heating the MZ arm, and continuous adjustment of through-port extinction ratio from 0dB to 27dB was achieved. Meanwhile, the 3dB bandwidth in the drop port changed from 0.11nm to 0.15nm due to the heating. The device had an ultra-compact footprint (1...

  3. Self-calibrating ultra-low noise, wide-bandwidth optomechanical accelerometer

    CERN Document Server

    Cervantes, Felipe Guzman; Pratt, Jon; Taylor, Jacob

    2013-01-01

    The reflection spectrum of an optical cavity is exquisitely sensitive to length variations, enabling precise and accurate displacement measurements. When combined with mechanical oscillators, such cavities can yield accelerometers of unprecedented resolution. Previously, accelerometer sensitivity enhancements were achieved by lowering the sensor's natural frequency and bandwidth. Detection near the thermal limit was achieved, but at high acceleration levels due to low oscillator mass. We present a novel self-calibrating accelerometer, capable of reaching nano-gn/rtHz sensitivities (micro-Gal/rtHz -- 1gn=9.81 m/s^2 -- equivalent displacement of attometer/rtHz) over a bandwidth of several kHz, and compare its accuracy to a calibrated commercial system. It consists of a compact (10.6 x 15 mm), high-mQ (5kg) fused-silica oscillator that utilizes fiber-optic micro-mirror cavities, for self-calibrated detection of the motions of its test-mass. This device provides a substantial improvement over conventional systems...

  4. Power allocation, bit loading and sub-carrier bandwidth sizing for OFDM-based cognitive radio

    Directory of Open Access Journals (Sweden)

    Desai Uday

    2011-01-01

    Full Text Available Abstract The function of the Radio Resource Management module of a Cognitive Radio (CR system is to evaluate the available resources and assign them to meet the Quality of Service (QoS objectives of the Secondary User (SU, within some constraints on factors which limit the performance of the Primary User (PU. While interference mitigation to the PU spectral band from the SU's transmission has received a lot of attention in recent literature; the novelty of our work is in considering a more realistic and effective approach of dividing the PU into sub-bands, and ensuring that the interference to each of them is below a specified threshold. With this objective, and within a power budget, we execute the tasks of power allocation, bit loading and sizing the sub-carrier bandwidth for an orthogonal frequency division multiplexing (OFDM-based SU. After extensively analyzing the solution form of the optimization problems posed for the resource allocation, we suggest iterative algorithms to meet the aforementioned objectives. The algorithm for sub-carrier bandwidth sizing is novel, and not previously presented in literature. A multiple SU scenario is also considered, which entails assigning sub-carriers to the users, besides the resource allocation. Simulation results are provided, for both single and multi-user cases, which indicate the effectiveness of the proposed algorithms in a CR environment.

  5. Bandwidth enhancement of a dual band planar monopole antenna using meandered microstrip feeding.

    Science.gov (United States)

    Ahsan, M R; Islam, M T; Habib Ullah, M; Misran, N

    2014-01-01

    A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (? r = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the -10 dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600 MHz-1 GHz) and at upper band is 28% (2.25 GHz-2.95 GHz). The measured maximum gains of -1.18 dBi and 4.87 dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications. PMID:24723832

  6. 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.

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

    Science.gov (United States)

    Ast, Stefan; Mehmet, Moritz; Schnabel, Roman

    2013-06-01

    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. PMID:23736610

  8. Bandwidth Enhancement of a Dual Band Planar Monopole Antenna Using Meandered Microstrip Feeding

    Science.gov (United States)

    Ahsan, M. R.; Islam, M. T.; Habib Ullah, M.; Misran, N.

    2014-01-01

    A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (?r = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the ?10?dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600?MHz–1?GHz) and at upper band is 28% (2.25?GHz–2.95?GHz). The measured maximum gains of ?1.18?dBi and 4.87?dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications. PMID:24723832

  9. How bandwidth selection algorithms impact exploratory data analysis using kernel density estimation.

    Science.gov (United States)

    Harpole, Jared K; Woods, Carol M; Rodebaugh, Thomas L; Levinson, Cheri A; Lenze, Eric J

    2014-09-01

    Exploratory data analysis (EDA) can reveal important features of underlying distributions, and these features often have an impact on inferences and conclusions drawn from data. Graphical analysis is central to EDA, and graphical representations of distributions often benefit from smoothing. A viable method of estimating and graphing the underlying density in EDA is kernel density estimation (KDE). This article provides an introduction to KDE and examines alternative methods for specifying the smoothing bandwidth in terms of their ability to recover the true density. We also illustrate the comparison and use of KDE methods with 2 empirical examples. Simulations were carried out in which we compared 8 bandwidth selection methods (Sheather-Jones plug-in [SJDP], normal rule of thumb, Silverman's rule of thumb, least squares cross-validation, biased cross-validation, and 3 adaptive kernel estimators) using 5 true density shapes (standard normal, positively skewed, bimodal, skewed bimodal, and standard lognormal) and 9 sample sizes (15, 25, 50, 75, 100, 250, 500, 1,000, 2,000). Results indicate that, overall, SJDP outperformed all methods. However, for smaller sample sizes (25 to 100) either biased cross-validation or Silverman's rule of thumb was recommended, and for larger sample sizes the adaptive kernel estimator with SJDP was recommended. Information is provided about implementing the recommendations in the R computing language. PMID:24885339

  10. The effect of finite bandwidth squeezed light on entanglement creation in the Dicke model

    International Nuclear Information System (INIS)

    We analyse the relation between local two-atom and total multi-atom entanglements in the Dicke system composed of a large number of atoms. We use concurrence as a measure of entanglement between two atoms in the multi-atom system, and the spin squeezing parameter as a measure of entanglement in the whole n-atom system. In addition, the influence of the squeezing phase and bandwidth on entanglement in the steady-state Dicke system is discussed. It is shown that the introduction of a squeezed field leads to a significant enhancement of entanglement between two atoms, and the entanglement increases with increasing degree of squeezing and bandwidth of the incident squeezed field. In the presence of a coherent field the entanglement exhibits a strong dependence on the relative phase between the squeezed and coherent fields, that can jump quite rapidly from unentangled to strongly entangled values when the phase changes from zero to ?. We find that the jump of the degree of entanglement is due to a flip of the spin squeezing from one quadrature component of the atomic spin to the other component when the phase changes from zero to ?. We also analyse the dependence of the entanglement on the number of atoms and find that, despite the reduction in the degree of entanglement between two atoms, a large entanglement is present in the whole n-atom system and the degree of entanglement increases as the number of atoms increases

  11. Phase loop bandwidth measurements on the advanced photon source 352 MHz rf systems

    International Nuclear Information System (INIS)

    Phase loop bandwidth tests were performed on the Advanced Photon Source storage ring 352-MHz rf systems. These measurements were made using the HP3563A Control Systems Analyzer, with the rf systems running at 30 kilowatts into each of the storage ring cavities, without stored beam. An electronic phase shifter was used to inject approximately 14 degrees of stimulated phase shift into the low-level rf system, which produced measureable response voltage in the feedback loops without upsetting normal rf system operation. With the PID (proportional-integral-differential) amplifier settings at the values used during accelerator operation, the measurement data revealed that the 3-dB response for the cavity sum and klystron power-phase loops is approximately 7 kHz and 45 kHz, respectively, with the cavities the primary bandwidth-limiting factor in the cavity-sum loop. Data were taken at various PID settings until the loops became unstable. Crosstalk between the two phase loops was measured

  12. 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.

  13. ±25 ppm repeatable measurement of trapezoidal pulses with 5 MHz bandwidth

    International Nuclear Information System (INIS)

    High-quality measurements of pulses are nowadays widely used in fields such as radars, pulsed lasers, electromagnetic pulse generators, and particle accelerators. Whilst literature is mainly focused on fast systems for nanosecond regime with relaxed metrological requirements, in this paper, the high-performance measurement of slower pulses in microsecond regime is faced. In particular, the experimental proof demonstration for a 15 MS/s, ±25 ppm repeatable acquisition system to characterize the flat-top of 3 ?s rise-time trapezoidal pulses is given. The system exploits a 5 MHz bandwidth circuit for analogue signal processing based on the concept of flat-top removal. The requirements, as well as the conceptual and physical designs are illustrated. Simulation results aimed at assessing the circuit performance are also presented. Finally, an experimental case study on the characterization of a pulsed power supply for the klystrons modulators of the Compact Linear Collider (CLIC) under study at CERN is reported. In particular, the metrological characterization of the prototype in terms of bandwidth, repeatability, and linearity is presented

  14. Large-aperture Wide-bandwidth Antireflection-coated Silicon Lenses for Millimeter Wavelengths

    Science.gov (United States)

    Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, Edward J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.; Hubmayr, J.; Irwin, K.; Newburgh, L.; Nibarger, J. P.; Page, L.; Quijada, Manuel A.; Schmitt, B. L.; Staggs, S. T.; Thornton, R.; Zhang, L.

    2013-01-01

    The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n 3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating.We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30deg with low cross polarization.We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

  15. Obtaining structural information of small proteins using solid-state nanopores and high-bandwidth measurements

    Science.gov (United States)

    Niedzwiecki, David; Lanci, Christopher; Saven, Jeffery; Drndic, Marija

    2015-03-01

    The use of biological nanopores sensors to characterize proteins has proved a fruitful field of study. Solid-state nanopores hold several advantages over their biological counterparts, including the ability to tune pore diameter and their robustness to external conditions. Despite these advantages, the use of solid-state nanopores for protein analysis has proved difficult due to rapid translocation times of proteins and poor signal-to-noise of small peptides. Recently, improvements in high-bandwidth acquisition and in signal-to-noise have made the study of small peptides using solid-state nanopores feasible. Here we report on the detection and characterization of peptides as small as 33 amino-acids in length using sub-10 nm thin silicon nitride nanopores, giving high signal levels, combined with high-bandwidth electronics. In addition we show differentiation between monomers and dimer forms of the GCN-4 p1 leucine zipper, a coil-coil structure, and compare this with the unstructured 33-mer. The differentiation between these two forms demonstrates the possibility of extracting useful structural information from short peptide structures using modern solid-state nanopore systems.

  16. Design optimization for relative bandwidth of left-handed metamaterials with split-ring resonators

    International Nuclear Information System (INIS)

    Due to their special properties, left-handed metamaterials have important potential applications in engineering. When an incident wave propagates through a periodic material with the dimension of its microstructure much smaller than the wavelength, the metamaterial can be regarded as a homogeneous medium, and its effective electromagnetic parameters (permittivity and permeability) in the frequency domain can be obtained with the S-parameters retrieval method. From this perspective, the design of a material with the desired left-handed characteristics becomes possible. By establishing automatic parametric modeling technology, we can study the transmission and reflection properties of left-handed metamaterials with arrays of split-ring resonators. Next, a whole flow chart of design optimization for improving left-handed metamaterial performance is proposed. Finally, the design method is illustrated through a numerical example including the shape and the size design of split-ring resonators to max relative bandwidth, based on parametric analysis of the left-handed relative bandwidths. Sequential quadratic programming and enumeration optimization are applied to solve the optimization problem

  17. Gas-filled cell as a narrow bandwidth bandpass filter in the VUV wavelength range

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2011-01-01

    We propose a method for spectrally filtering radiation in the VUV wavelength range by means of a monochromator constituted by a cell filled with a resonantly absorbing rare gas. Around particular wavelengths, the gas exhibits narrow-bandwidth absorbing resonances following the Fano profile. In particular, within the photon energy range 60 eV - 65 eV, the correlation index of the Fano profiles for the photo-ionization spectra in Helium is equal to unity, meaning that the minimum of the cross-section is exactly zero. For sufficiently large column density in the gas cell, the spectrum of the incoming radiation will be attenuated by the background cross-section of many orders of magnitude, except for those wavelengths close to the point where the cross-section is zero. Remarkable advantages of a gas monochromator based on this principle are simplicity, efficiency and narrow-bandwidth. A gas monochromator installed in the experimental hall of a VUV SASE FEL facility would enable the delivery of a single-mode VUV l...

  18. Dual Polarized near Field Probe Based on OMJ in Waveguide Technology Achieving More Than Octave Bandwidth

    DEFF Research Database (Denmark)

    Foged, L. J.; Giacomini, A.

    2014-01-01

    In classic probe-corrected spherical NF measurements, one of the main concerns is the probe [1], [2], [3]. Standard NF-FF transformation software applies probe correction with the assumption that the probe pattern behaves with ?=±1 azimuthal dependence. In reality, any physically realizable probe is just an approximation to this ideal case. Probe excitation errors, finite manufacturing tolerances and probe interaction with the mounting interface and absorbers are examples of uncertainties that can lead to presence of higher-order spherical modes in the probe pattern [4], [5]. Although probe correction techniques for high-order probes are feasible [6], they are highly demanding in terms of implementation complexity as well as in terms of calibration and post-processing time. In this paper, a new OMJ designed entirely in waveguide and capable of covering more than an octave bandwidth is presented. The excitation purity of the balanced feeding is limited only by the manufacturing accuracy of the waveguide. The paper presents the waveguide based OMJ concept including probe design covering the bandwidth from 18 to 40 GHz using single and dual apertures. The experimental validation is completed with measurements on the dual aperture probe at the DTU-ESA Spherical Near-Field facility in Denmark.

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

    International Nuclear Information System (INIS)

    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. (paper)

  20. Deterministic Formulization of End-to-End Delay and Bandwidth Efficiency for Multicast Systems

    Directory of Open Access Journals (Sweden)

    Syed S. Rizvi

    2009-11-01

    Full Text Available End-System multicasting (ESM is a promising application-layer scheme that has been recently proposed for implementing multicast routing in the application layer as a practical alternative to the IP multicasting. Moreover, ESM is an efficient application layer solution where all the multicast functionality is shifted to the end users. However, the limitation in bandwidth and the fact that the message needs to be forwarded from host-to-host using unicast connection, and consequently incrementing the end-to-end delay of the transmission process, contribute to the price to pay for this new approach. Therefore, supporting high-speed real-time applications such as live streaming multimedia, videoconferencing, distributed simulations, and multiparty games require a sound understanding of these multicasting schemes such as IP multicast and ESM and the factors that might affect the end-user requirements. In this paper, we present both the analytical and the mathematical models for formalizing the end-to-end delay and the bandwidth efficiency of both IP and ESM multicast system. For the sake of the experimental verifications of the proposed models, numerical and simulation results are presented in this paper. Finally, the proposed formulization can be used to design and implement a more robust and efficient multicast systems for the future networks