Asymmetric coherent transmission for single particle diode and gyroscope
Yang, S.; Song, Z; Sun, C. P.
2009-01-01
We study the single particle scattering process in a coherent multi-site system consisting of a tight-binding ring threaded by an Aharonov-Bohm flux and several attaching leads. The asymmetric behavior of scattering matrix is discovered analytically in the framework of both Bethe Ansatz and Green's function formalism. It is found that, under certain conditions, a three-site electronic system can behave analogous to a perfect semiconductor diode where current flows only in one direction. The g...
Asymmetric coherent transmission for single particle diode and gyroscope
Yang, S; Sun, C P
2009-01-01
We study the single particle scattering process in a coherent multi-site system consisting of a tight-binding ring threaded by an Aharonov-Bohm flux and several attaching leads. The asymmetric behavior of scattering matrix is discovered analytically in the framework of both Bethe Ansatz and Green's function formalism. It is found that, under certain conditions, a three-site electronic system can behave analogous to a perfect semiconductor diode where current flows only in one direction. The general result is also valid for a neutral particle system since the effective magnetic flux may be implemented by a globe rotation. This observation means that the three-site system can serve as an orientation measuring gyroscope due to the approximate linear dependence of the current difference of two output leads on the rotational angular velocity.
Asymmetric acoustic transmission in multiple frequency bands
We report both experimentally and numerically that the multi-band device of the asymmetric acoustic transmission is realized by placing two periodic gratings with different periods on both sides of two brass plates immersed in water. The asymmetric acoustic transmission can exist in four frequency bands below 1500 kHz, which arises from the interaction between various diffractions from the two gratings and Lamb modes in the brass plates immersed in water. The results indicate that the device has the advantages of multiple band, broader bandwidth, and simpler structure. Our finding should have great potential applications in ultrasonic devices
Ultrafast Transmission Systems using Coherent Technology
Ludwig, Reinhold; Richter, Thomas; Palushani, Evarist;
2011-01-01
We review recent progress in ultrafast transmission systems. Using coherent detection for simultaneous demultiplexing and demodulation enabled single channel serial 10.2Tb/s transmission over 29km as well as transmission impairment compensation far beyond electronic speed limits.......We review recent progress in ultrafast transmission systems. Using coherent detection for simultaneous demultiplexing and demodulation enabled single channel serial 10.2Tb/s transmission over 29km as well as transmission impairment compensation far beyond electronic speed limits....
Tunable Dirac points and perfect transmission in asymmetric graphene superlattices
Zhang, Rui-Li; Li, Jin-Jing; Zhou, Yu; Peng, Ru-Wen; Huang, Run-Sheng; Wang, Mu
2015-08-01
We investigated the electronic band structures and transport properties in asymmetric graphene superlattices (AGSLs). Their asymmetric distribution of potentials can induce extra Dirac points (DPs) that are absent in periodic and symmetric graphene superlattices. The emergence and location of the DPs in the k space can be manipulated by selecting the special structure of the AGSL. As a result, tunable perfect transmissions are obtained in the system. Moreover, the conductance and Fano factor present interesting oscillatory behaviors. These findings may be used for the design of graphene-based electronic devices.
Energy unidirectional transmission in an asymmetrically finite transmission line
The phenomenon of energy unidirectional transmission is numerically investigated by using a system of two coupled discrete nonlinear electrical transmission lines, each line of the network contains a finite number of cells and has different pass band structures, respectively. Using numerical simulations, we examine the frequency multiplication of the driving frequency and the lattice filtering effect in the line. These lead to the generation of energy unidirectional transmission. In the present work, energy is carried by the second harmonic wave in the pass band. In addition, we also study the dependence of the energy efficiency on the driving amplitude and other parameters of the model, such as the system size and the nonlinear coefficient, by calculation. Furthermore, after detailed numerical simulation, an experimental demonstration is realized. The experimental results agree with those in simulation qualitatively. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Design and Transmission Analysis of an Asymmetrical Spherical Parallel Manipulator
Wu, Guanglei; Caro, Stéphane; Wang, Jiawei
2015-01-01
This paper presents an asymmetrical spherical parallel manipulator and its transmissibility analysis. This manipulator contains a center shaft to both generate a decoupled unlimited-torsion motion and support the mobile platform for high positioning accuracy. This work addresses the transmission...... analysis and optimal design of the proposed manipulator based on its kinematic analysis. The input and output transmission indices of the manipulator are defined for its optimum design based on the virtual coefficient between the transmission wrenches and twist screws. The sets of optimal parameters are...... identified and the distribution of the transmission index is visualized. Moreover, a comparative study regarding to the performances with the symmetrical spherical parallel manipulators is conducted and the comparison shows the advantages of the proposed manipulator with respect to its spherical parallel...
ASYMMETRIC PRICE TRANSMISSION BETWEEN POLISH AND GERMAN FEED WHEAT MARKETS
Mariusz Hamulczuk
2015-03-01
Full Text Available The aim of the paper was an assessment of possible asymmetry in price transmission between Polish and German feed wheat prices. TAR and M-TAR procedures were employed for testing price symmetry, as well as ECM framework. The results obtained indicate the existence of the long-run relationship between Polish and German wheat prices, as well as asymmetric adjustment of prices to the long-run equilibrium relationship.
ASYMMETRIC PRICE TRANSMISSION BETWEEN POLISH AND GERMAN FEED WHEAT MARKETS
Mariusz Hamulczuk
2015-01-01
The aim of the paper was an assessment of possible asymmetry in price transmission between Polish and German feed wheat prices. TAR and M-TAR procedures were employed for testing price symmetry, as well as ECM framework. The results obtained indicate the existence of the long-run relationship between Polish and German wheat prices, as well as asymmetric adjustment of prices to the long-run equilibrium relationship.
Digital processing optical transmission and coherent receiving techniques
Binh, Le Nguyen
2013-01-01
With coherent mixing in the optical domain and processing in the digital domain, advanced receiving techniques employing ultra-high speed sampling rates have progressed tremendously over the last few years. These advances have brought coherent reception systems for lightwave-carried information to the next stage, resulting in ultra-high capacity global internetworking. Digital Processing: Optical Transmission and Coherent Receiving Techniques describes modern coherent receiving techniques for optical transmission and aspects of modern digital optical communications in the most basic lines. The
Optical nonreciprocal transmission in an asymmetric silicon photonic crystal structure
Wu, Zheng; Chen, Juguang; Ji, Mengxi; Huang, Qingzhong; Xia, Jinsong; Wang, Yi, E-mail: yingwu2@126.com, E-mail: ywangwnlo@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wu, Ying, E-mail: yingwu2@126.com, E-mail: ywangwnlo@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)
2015-11-30
An optical nonreciprocal transmission (ONT) is realized by employing the nonlinear effects in a compact asymmetric direct-coupled nanocavity-waveguide silicon photonic crystal structure with a high loaded quality factor (Q{sub L}) of 42 360 and large extinction ratio exceeding 30 dB. Applying a single step lithography and successive etching, the device can realize the ONT in an individual nanocavity, alleviating the requirement to accurately control the resonance of the cavities. A maximum nonreciprocal transmission ratio of 21.1 dB as well as a working bandwidth of 280 pm in the telecommunication band are obtained at a low input power of 76.7 μW. The calculated results by employing a nonlinear coupled-mode model are in good agreement with the experiment.
Optical nonreciprocal transmission in an asymmetric silicon photonic crystal structure
An optical nonreciprocal transmission (ONT) is realized by employing the nonlinear effects in a compact asymmetric direct-coupled nanocavity-waveguide silicon photonic crystal structure with a high loaded quality factor (QL) of 42 360 and large extinction ratio exceeding 30 dB. Applying a single step lithography and successive etching, the device can realize the ONT in an individual nanocavity, alleviating the requirement to accurately control the resonance of the cavities. A maximum nonreciprocal transmission ratio of 21.1 dB as well as a working bandwidth of 280 pm in the telecommunication band are obtained at a low input power of 76.7 μW. The calculated results by employing a nonlinear coupled-mode model are in good agreement with the experiment
Asymmetric transmission: a generic property of two-dimensional periodic patterns
Asymmetric transmission of circularly polarized waves is a well-established property of lossy, anisotropic, two-dimensionally chiral patterns. Here we show that asymmetric transmission can be observed for oblique incidence onto any lossy periodically structured plane. Our results greatly expand the range of natural and artificial materials in which directionally asymmetric transmission can be expected, making it a cornerstone electromagnetic effect rather than a curiosity of planar chiral metamaterials. Prime candidates for asymmetric transmission at oblique incidence are rectangular arrays of plasmonic spheres or semiconductor quantum dots, lossy double-periodic gratings and planar metamaterial structures
Asymmetric transmission of surface plasmon polaritons on planar gratings
Kuzmiak, Vladimir
2016-01-01
We describe a surface structure consisting of a metal-air interface where the metallic part consists of two metallic segments with a periodic modulation of the interface between them. Such a structure possesses a different transmissivity for a surface plasmon polariton incident on it from one side of it than it has for a surface plasmon polariton incident on it from the opposite side. This asymmetric transmission of a surface plasmon polariton is based on the suppression of the zero-order Bragg beam which, for a certain value of the modulation depth, is not transmitted through the structure, while the diffraction efficiencies of the +1 and -1 Bragg beams can be modified by varying the period of grating and/or the angle of incidence. For a certain range of the incidence angle one can observe asymmetry in transmittance for the -1 mode while the +1 mode is completely suppressed. By varying the material and geometrical parameters of the diffractive structure one can control the contrast transmission that characte...
CAI Xu-Hong; LIN Xu-Sheng; LAN Sheng
2008-01-01
By carrying out the two ideas of asymmetrical confinement and asymmetrical response into the photonic crystal (PC) structures that contain two or more nonlinear defects, we find that significantly unidirectional transmission can be achieved while the transmission for the positive launch direction maintains at large values. Our analyses are supported by the simulation results based on the finite-difference time-domain technique.
Non-reciprocal transmission in photonic lattices based on unidirectional coherent perfect absorption
Longhi, Stefano
2015-01-01
A method for realizing asymmetric (one-way) transmission of discretized light in modulated, linear and purely passive optical lattices is suggested, which exploits the idea of unidirectional coherent perfect absorption. The system consists of a linear photonic lattice of coupled resonators or waveguides, side coupled to a chain of lossy elements, in which light can avoid the occupation of the dissipative sites when propagating in one way, but not in the opposite one. Non-reciprocity requires modulation of the resonator/waveguide parameters, realizing a dissipative optical Aharonov-Bohm diode with non-reciprocal behavior.
Damage Detection and Quantification Using Transmissibility Coherence Analysis
Yun-Lai Zhou
2015-01-01
Full Text Available A new transmissibility-based damage detection and quantification approach is proposed. Based on the operational modal analysis, the transmissibility is extracted from system responses and transmissibility coherence is defined and analyzed. Afterwards, a sensitive-damage indicator is defined in order to detect and identify the severity of damage and compared with an indicator developed by other authors. The proposed approach is validated on data from a physics-based numerical model as well as experimental data from a three-story aluminum frame structure. For both numerical simulation and experiment the results of the new indicator reveal a better performance than coherence measure proposed in Rizos et al., 2008, Rizos et al., 2002, Fassois and Sakellariou, 2007, especially when nonlinearity occurs, which might be further used in real engineering. The main contribution of this study is the construction of the relation between transmissibility coherence and frequency response function coherence and the construction of an effective indicator based on the transmissibility modal assurance criteria for damage (especially for minor nonlinearity detection as well as quantification.
Tunable asymmetric transmission of THz wave through a graphene planar chiral structure
Zhao, Junyang; Zhang, Jianfa; Zhu, Zhihong; Yuan, Xiaodong; Qin, Shiqiao
2015-01-01
In this letter, we show that asymmetric transmission of circularly polarized waves through a nanostructured planar chiral graphene film can be observed in terahertz range. The asymmetric transmission effect of monatomic layer graphene closely resembles that of metallic planar chiral nanostructures which has previously been demonstrated. And the relative enantiomeric difference in the total transmission varies with the change of graphene's Fermi level. The plasmonic excitation in the graphene ...
Coherent data transmission with microresonator Kerr frequency combs
Pfeifle, Joerg; Wegner, Daniel; Brasch, Victor; Herr, Tobias; Hartinger, Klaus; Li, Jingshi; Hillerkuss, David; Schmogrow, Rene; Holzwarth, Ronald; Freude, Wolfgang; Leuthold, Juerg; Kippenberg, Tobias J; Koos, Christian
2013-01-01
Optical frequency combs enable coherent data transmission on hundreds of wavelength channels and have the potential to revolutionize terabit communications. Generation of Kerr combs in nonlinear integrated microcavities represents a particularly promising option enabling line spacings of tens of GHz, compliant with wavelength-division multiplexing (WDM) grids. However, Kerr combs may exhibit strong phase noise and multiplet spectral lines, and this has made high-speed data transmission impossible up to now. Recent work has shown that systematic adjustment of pump conditions allows generating low phase-noise Kerr combs with singlet spectral lines. Here, by employing an integrated Si3N4 microresonator, we demonstrate that Kerr combs are suited for coherent data transmission with advanced modulation formats that pose stringent requirements on the spectral purity of the optical source. In our experiment, we encode a data stream of 392 Gbit/s on subsequent lines of a Kerr comb using quadrature phase shift keying (...
Stathopoulos, N A; Savaidis, S P; Botsialas, A; Ioannidis, Z C; Georgiadou, D G; Vasilopoulou, M; Pagiatakis, G
2015-02-20
A generalized transmission line method (TLM) that provides reflection and transmission calculations for a multilayer dielectric structure with coherent, partial coherent, and incoherent layers is presented. The method is deployed on two different application fields. The first application of the method concerns the thickness measurement of the individual layers of an organic light-emitting diode. By using a fitting approach between experimental spectral reflectance measurements and the corresponding TLM calculations, it is shown that the thickness of the films can be estimated. The second application of the TLM concerns the calculation of the external quantum efficiency of an organic photovoltaic with partially coherent rough interfaces between the layers. Numerical results regarding the short circuit photocurrent for different layer thicknesses and rough interfaces are provided and the performance impact of the rough interface is discussed in detail. PMID:25968218
Tunable asymmetric transmission of THz wave through a graphene planar chiral structure
Zhao, Junyang; Zhu, Zhihong; Yuan, Xiaodong; Qin, Shiqiao
2015-01-01
In this letter, we show that asymmetric transmission of circularly polarized waves through a nanostructured planar chiral graphene film can be observed in terahertz range. The asymmetric transmission effect of monatomic layer graphene closely resembles that of metallic planar chiral nanostructures which has previously been demonstrated. And the relative enantiomeric difference in the total transmission varies with the change of graphene's Fermi level. The plasmonic excitation in the graphene nanostructure is the enantiometically sensitive which is asymmetric for opposite propagating directions. This phenomenon will deepen our understanding of light-matter interactions in planar chiral structures and may find applications in polarization-sensitive devices, sensors, detectors and other areas.
Loss Aversion and the Asymmetric Transmission of Monetary Policy
Santoro, Emiliano; Petrella, Ivan; Pfajfar, Damjan;
2014-01-01
There is widespread evidence that monetary policy exerts asymmetric effects on output over contractions and expansions in economic activity, while price responses display no sizeable asymmetry. To rationalize these facts we develop a dynamic general equilibrium model where households’ utility...
Coherent control of surface plasmon polariton mediated optical transmission
We demonstrate the coherent control of the surface plasmon polariton mediated optical transmission through arrays of nano-holes in a gold film on a garnet substrate by a standing surface acoustic wave (SAW) induced by a sequence of ultrashort laser pulses. The transmission of the pump pulse through the holes results in a periodic pattern of shock-waves leading, via interference, to a standing SAW. The resulting modulation frequency is determined by the periodicity of the arrays. The polarization of the transmitted light is modulated as well via a strain-induced linear dichroism
Coherent control of surface plasmon polariton mediated optical transmission
Guyader, L Le; Kirilyuk, A; Rasing, Th [IMM, Radboud University Nijmegen, Toernooiveld 1, 6525ED Nijmegen (Netherlands); Wurtz, G A; Zayats, A V [Centre for Nanostructured Media, IRCEP, The Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom); Alkemade, P F A [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Smolyaninov, I I [Department of Electrical and Computer Engineering, University of Maryland, College Park, MD (United States)], E-mail: l.leguyader@science.ru.nl
2008-10-07
We demonstrate the coherent control of the surface plasmon polariton mediated optical transmission through arrays of nano-holes in a gold film on a garnet substrate by a standing surface acoustic wave (SAW) induced by a sequence of ultrashort laser pulses. The transmission of the pump pulse through the holes results in a periodic pattern of shock-waves leading, via interference, to a standing SAW. The resulting modulation frequency is determined by the periodicity of the arrays. The polarization of the transmitted light is modulated as well via a strain-induced linear dichroism.
Bredtmann, Timm; Manz, Jörn; Zhao, Jian-Ming
2016-05-19
The quantum theory of concerted electronic and nuclear fluxes (CENFs) during coherent periodic tunnelling from reactants (R) to products (P) and back to R in molecules with asymmetric double-well potentials is developed. The results are deduced from the solution of the time-dependent Schrödinger equation as a coherent superposition of two eigenstates; here, these are the two states of the lowest tunnelling doublet. This allows the periodic time evolutions of the resulting electronic and nuclear probability densities (EPDs and NPDs) as well as the CENFs to be expressed in terms of simple sinusodial functions. These analytical results reveal various phenomena during coherent tunnelling in asymmetric double-well potentials, e.g., all EPDs and NPDs as well as all CENFs are synchronous. Distortion of the symmetric reference to a system with an asymmetric double-well potential breaks the spatial symmetry of the EPDs and NPDs, but, surprisingly, the symmetry of the CENFs is conserved. Exemplary application to the Cope rearrangement of semibullvalene shows that tunnelling of the ideal symmetric system can be suppressed by asymmetries induced by rather small external electric fields. The amplitude for the half tunnelling, half nontunnelling border is as low as 0.218 × 10(-8) V/cm. At the same time, the delocalized eigenstates of the symmetric reference, which can be regarded as Schrödinger's cat-type states representing R and P with equal probabilities, get localized at one or the other minima of the asymmetric double-well potential, representing either R or P. PMID:26799383
Companding transform based SPM compensation in coherent optical OFDM transmission.
Chung, Hwan Seok; Chang, Sun Hyok; Kim, Kwangjoon
2011-12-12
We demonstrate a mitigation of fiber nonlinearity based on μ-law companding transform in coherent optical OFDM transmissions. High peak-to-average power ratio (PAPR) increases fiber nonlinear impairments caused by the Kerr effect in optical fiber. The μ-law companding modifies amplitude profile of OFDM signal with time domain signal processing, which reduces high PAPR of OFDM signal. The effects of companding parameter on noise enhancement and PAPR variation are presented. The impacts of companding transform on system performances are evaluated in a single polarization system as well as polarization multiplexed system. The resolution of analog-to-digital converter (ADC), dispersion map of transmission link, and launch power tolerance are also considered. The results of bit-error-rate (BER) measurements show that the μ-law companding improves OSNR margin over 5.5 dB after transmission of 1,040 km over SMF. PMID:22274091
Loss aversion and the asymmetric transmission of monetary policy
Gaffeo, E.; Petrella, I.; Pfajfar, D.; Santoro, E.
2014-01-01
There is widespread evidence that monetary policy exerts asymmetric effects on output over contractions and expansions in economic activity, while price responses display no sizeable asymmetry. To rationalize these facts we develop a dynamic general equilibrium model where households’ utility depend
Li, Yue; Fei, Guang Tao; Xu, Shao Hui; Shang, Guo Liang; De Zhang, Li
2016-01-01
The phenomenon of extraordinary and multi-broadband optical transmission through sub-wavelength metallic grating with symmetry breaking has been theoretically investigated. Under normal incident light, the radiative and dark modes appear in adjacent slits of the grating with asymmetric heights. Through the destructive interference of alternative radiative and dark modes, multiple broadband transmission and enhanced light propagation is realized. The counter-propagating light circulation results in sharp dips in the transmission spectrum. These characteristics of the asymmetric grating could provide highly controllable ways to design novel devices.
Cai, Jianjun; Shen, Xueju; Lin, Chao
2016-01-01
We propose a security-enhanced asymmetric optical cryptosystem based on coherent superposition and equal modulus decomposition by combining full phase encryption technique with our previous cryptosystem. In the encryption process, the original image is phase encoded rather than bonded with a RPM. In the decryption process, two phase-contrast filters (PCFs) are employed to obtain the plaintext. As a consequence, the new cryptosystem guarantees high-level security to the attack based on iterative Fourier transform and maintains the good performance of our previous cryptosystem, especially conveniences. Some numerical simulations are presented to verify the validity and the performance of the modified cryptosystem.
Chen, Yuan; Deng, Li [Department of Applied Physics, East China Jiaotong University, Nanchang, 330013 (China); Chen, Aixi, E-mail: aixichen@ecjtu.jx.cn [Department of Applied Physics, East China Jiaotong University, Nanchang, 330013 (China); Institute for Quantum Computing, University of Waterloo, Ontario N2L 3G1 (Canada)
2015-02-15
We investigate the nonlinear optical phenomena of the optical bistability and multistability via spontaneously generated coherence in an asymmetric double quantum well structure coupled by a weak probe field and a controlling field. It is shown that the threshold and hysteresis cycle of the optical bistability can be conveniently controlled only by adjusting the intensity of the SGC or the controlling field. Moreover, switching between optical bistability and multistability can be achieved. These studies may have practical significance for the preparation of optical bistable switching device.
Petrol and Crude Oil Prices: Asymmetric Price Transmission
Wlazlowski, Szymon
2003-01-01
This paper examines the relationship between crude oil prices, the dollar-pound exchange rate and petrol prices in the UK over the period 1982-2001. Quantitative methods were used to examine the existence of the long-run equilibrium and test for the presence of asymmetric patterns in the short-run responses to upstream price changes. Also the degree of asymmetry in the adjustment towards long-run equilibrium was analysed. Results confirm that short-run response is greater for increases in ups...
Transmission Probability of an Ultracold Atom in the Presence of Atomic Coherence
熊锦; 储开芹; 张智明
2002-01-01
We investigate the transmission probability of an ultracold V-type three-level atom passing through a micromaser cavity, in the presence of atomic coherence which is established by a coherent driving field. We show that the transmissibility of this micromaser system with the atomic coherence is better than that of the ordinary micromaser system without atomic coherence. When the driving field is strong enough, for any cavity length the ultracold atom can pass through the micromaser cavity freely.
Tunable asymmetric transmission of THz wave through a graphene chiral metasurface
Zhao, Junyang; Zhang, Jianfa; Zhu, Zhihong; Yuan, Xiaodong; Qin, Shiqiao
2016-09-01
In this paper, we show numerically that the asymmetric transmission of circularly polarized waves through a graphene chiral metasurface can be observed in the THz range. The relative enantiomeric difference in the total transmission varies with the change of graphene’s Fermi level. The plasmonic excitation in the graphene metasurface is enantiomerically sensitive, which is asymmetric for opposite propagating directions. This phenomenon will deepen our understanding of light-matter interactions in planar chiral structures and may find applications in polarization-sensitive devices, sensors, detectors and other areas.
LIN Xu-Sheng; LAN Sheng
2005-01-01
@@ We investigate the unidirectional transmission behaviour of an asymmetrically confined photonic crystal (PC)defect with Kerr nonlinearity. Basically, the unidirectional transmission originates from the strong dependence of the threshold input power for the sharp increase of transmission on the launch direction of the input wave. This can be well explained in the framework of the coupled mode theory. Our theoretical analysis reveals the existence of an upper limit for the transmission contrast when such a single PC defect is employed. This is supported by the simulation results based on the nonlinear finite-difference time-domain technique.
Henry de-Graft Acquah
2013-01-01
Full Text Available Information Criteria provides an attractive basis for selecting the best model from a set of competing asymmetric price transmission models or theories. However, little is understood about the sensitivity of the model selection methods to model complexity. This study therefore fits competing asymmetric price transmission models that differ in complexity to simulated data and evaluates the ability of the model selection methods to recover the true model. The results of Monte Carlo experimentation suggest that in general BIC, CAIC and DIC were superior to AIC when the true data generating process was the standard error correction model, whereas AIC was more successful when the true model was the complex error correction model. It is also shown that the model selection methods performed better in large samples for a complex asymmetric data generating process than with a standard asymmetric data generating process. Except for complex models, AIC's performance did not make substantial gains in recovery rates as sample size increased. The research findings demonstrate the influence of model complexity in asymmetric price transmission model comparison and selection.
Asymmetric transmission through a flux-controlled non-Hermitian scattering center
Li, X. Q.; Zhang, X. Z.; Zhang, G.; Song, Z.
2015-03-01
We study the possibility of asymmetric transmission induced by a non-Hermitian scattering center embedded in a one-dimensional waveguide, motivated by the aim of realizing quantum diodes in a non-Hermitian system. It is shown that a PT -symmetric non-Hermitian scattering center always has symmetric transmission although the dynamics within the isolated center can be unidirectional, especially at its exceptional point. We propose a concrete scheme based on a flux-controlled non-Hermitian scattering center, which comprises a non-Hermitian triangular ring threaded by an Aharonov-Bohm flux. The analytical solution shows that such a complex scattering center acts as a diode at the resonant energy level of the spectral singularity, exhibiting perfect unidirectionality of the transmission. The connections between the phenomena of the asymmetric transmission and reflectionless absorption are also discussed.
Asymmetric transmission through a flux-controlled non-Hermitian scattering center
Li, X. Q.; Zhang, X. Z.; G. Zhang; Song, Z.
2014-01-01
We study the possibility of asymmetric transmission induced by a non-Hermitian scattering center embedded in a one-dimensional waveguide, motivated by the aim of realizing quantum diode in a non-Hermitian system. It is shown that a $\\mathcal{PT}$ symmetric non-Hermitian scattering center always has symmetric transmission although the dynamics within the isolated center can be unidirectional, especially at its exceptional point. We propose a concrete scheme based on a flux-controlled non-Hermi...
Yue Wang; Yijing Tong; Xin Zhang
2016-01-01
Transmission spectra of terahertz waves through a two-dimensional array of asymmetric rectangular apertures on super-aligned multi-walled carbon nanotube films were obtained experimentally. In this way, the anisotropic transmission phenomena of carbon nanotube films were observed. For a terahertz wave polarization parallel to the orientation of the carbon nanotubes and along the aperture short axis, sharp resonances were observed and the resonance frequencies coincided well with the surface p...
Asymmetric parametric amplification in nonlinear left-handed transmission lines
Powell, David A.; Ilya V. Shadrivov; Yuri S. Kivshar
2008-01-01
We study parametric amplification in nonlinear left-handed transmission lines, which serve as model systems for nonlinear negative index metamaterials. We experimentally demonstrate amplification of a weak pump signal in three regimes: with the signal in the left-handed band, with the signal in the stop band, and with the signal at a defect frequency. In particular, we demonstrate the amplification of the incident wave by up to 15dB in the left-handed regime.
Bo, Hu; Jie, Shi; Sheng-Guo, Shi; Yu, Sun; Zhong-Rui, Zhu
2016-02-01
We propose an underwater asymmetric acoustic transmission structure comprised of two media each with a gradient change of acoustic impedance. By gradually increasing the acoustic impedances of the media, the propagating direction of the acoustic wave can be continuously bent, resulting in allowing the acoustic wave to pass through along the positive direction and blocking acoustic waves from the negative one. The main advantages of this structure are that the asymmetric transmission effect of this structure can be realized and enhanced more easily in water. We investigate both numerically and experimentally the asymmetric transmission effect. The experimental results show that a highly efficient asymmetric acoustic transmission can be yielded within a remarkable broadband frequency range, which agrees well with the numerical prediction. It is of potential practical significance for various underwater applications such as reducing vibration and noise. Project supported by the National Natural Science Foundation of China (Grant Nos. 11204049 and 11204050), the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (Grant No. IRT1228), and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20122304120023 and 20122304120011).
Berec, V.
2016-02-01
We study the coupling and control adaptation of a hybrid electron-nuclear spin system using the laser mediated proton beam in MeV energy regime. The asymmetric control mechanism is based on exact optimization of both: the measure of exchange interaction and anisotropy of the hyperfine interaction induced in the resonance with optimal channeled protons (CP) superfocused field, allowing manipulation over arbitrary localized spatial centers while addressing only the electron spin. Using highly precise and coherent proton channeling regime we have obtained efficient pulse shaping separator technique aimed for spatio-temporal engineering of quantum states, introducing a method for control of nuclear spins, which are coupled via anisotropic hyperfine interactions in isolated electron spin manifold, without radio wave (RW) pulses. The presented method can be efficiently implemented in synchronized spin networks with the purpose to facilitate preservation and efficient transfer of experimentally observed quantum particle states, contributing to the overall background noise reduction.
Route-asymmetrical light transmission of a fiber-chip-fiber optomechanical system
Liu, Li; Ding, Yunhong; Cai, Xinlun;
2016-01-01
. Employing a fiber-chip-fiber optomechanical system, our scheme has successfully achieved a broad operation bandwidth of at least 24 nm and an ultra-high route-asymmetrical transmission ratio (RATR) up to 63 dB. The route-asymmetrical device has been demonstrated effectively with not only the continuous......-wave (CW) light but also 10 Gbit/s on-off-keying (OOK) digital signals. Above mentioned unique features can be mostly attributed to the significant characteristics of the thermal radiative effect, which could cause a fiber displacement up to tens of microns. The powerful and significant thermal radiative...
Su, Xiaoshi; Norris, Andrew N
2016-06-01
Gradient index (GRIN), refractive, and asymmetric transmission devices for elastic waves are designed using a solid with aligned parallel gaps. The gaps are assumed to be thin so that they can be considered as parallel cracks separating elastic plate waveguides. The plates do not interact with one another directly, only at their ends where they connect to the exterior solid. To formulate the transmission and reflection coefficients for SV- and P-waves, an analytical model is established using thin plate theory that couples the waveguide modes with the waves in the exterior body. The GRIN lens is designed by varying the thickness of the plates to achieve different flexural wave speeds. The refractive effect of SV-waves is achieved by designing the slope of the edge of the plate array, and keeping the ratio between plate length and flexural wavelength fixed. The asymmetric transmission of P-waves is achieved by sending an incident P-wave at a critical angle, at which total conversion to SV-wave occurs. An array of parallel gaps perpendicular to the propagation direction of the reflected waves stop the SV-wave but let P-waves travel through. Examples of focusing, steering, and asymmetric transmission devices are discussed. PMID:27369165
Coherent Control of Transmission Probability of a Cold Atom Through Microcavity Potentials
何小灵; 杜四德; 陈灏; 陆靖
2003-01-01
We investigate the transmission probability of a two-level cold atom through a quantum microcavity when the atom is initially prepared in a coherent superposition of its excited state and ground state. We can control the transmissibility of the atom by this initial coherence. Remarkable step and switch effect are discovered in the atomic transmission for the case of weak and intense quantized fields, respectively.
An analysis method for asymmetric resonator transmission applied to superconducting devices
Khalil, M. S.; Stoutimore, M. J. A.; Wellstood, F. C.; Osborn, K. D.
2012-03-01
We examine the transmission through nonideal microwave resonant circuits. The general analytical resonance line shape is derived for both inductive and capacitive coupling with mismatched input and output transmission impedances, and it is found that, for certain non-ideal conditions, the line shape is asymmetric. We describe an analysis method for extracting an accurate internal quality factor (Qi), the diameter correction method (DCM), and compare it to the conventional method used for millikelvin resonator measurements, the φ rotation method (φRM). We analytically find that the φRM deterministically overestimates Qi when the asymmetry of the resonance line shape is high, and that this error is eliminated with the DCM. A consistent discrepancy between the two methods is observed when they are used to analyze both simulations from a numerical linear solver and data from asymmetric coplanar superconducting thin-film resonators.
Transmission probability of the two-mode mazer with injected atomic coherence
袁春华; 张智明
2005-01-01
The transmission probability of the two-mode mazer injected with V-type three-level atoms is studied, and the effects of the atomic coherence on it are examined. It is shown that the atomic coherence can affect the transmission probability. In the plots of the atomic transmission probability versus the dimensionless centre-of-mass momentum, there are resonance peaks and non-resonance platforms. The heights of these resonance peaks and non-resonance platforms can be adjusted by the atomic coherence parameter and by the relative coupling strength of the two transition channels.
Yue Wang
2016-04-01
Full Text Available Transmission spectra of terahertz waves through a two-dimensional array of asymmetric rectangular apertures on super-aligned multi-walled carbon nanotube films were obtained experimentally. In this way, the anisotropic transmission phenomena of carbon nanotube films were observed. For a terahertz wave polarization parallel to the orientation of the carbon nanotubes and along the aperture short axis, sharp resonances were observed and the resonance frequencies coincided well with the surface plasmon polariton theory. In addition, the minima of the transmission spectra were in agreement with the location predicted by the theory of Wood’s anomalies. Furthermore, it was found that the resonance profiles through the carbon nanotube films could be well described by the Fano model.
Tunable hard X-ray spectrometer utilizing asymmetric planes of a quartz transmission crystal
Seely, John F.; Henins, Albert; Feldman, Uri
2016-05-01
A Cauchois type hard x-ray spectrometer was developed that utilizes the (301) diffraction planes at an asymmetric angle of 23.51° to the normal to the surface of a cylindrically curved quartz transmission crystal. The energy coverage is tunable by rotating the crystal and the detector arm, and spectra were recorded in the 8 keV to 20 keV range with greater than 2000 resolving power. The high resolution results from low aberrations enabled by the nearly perpendicular angle of the diffracted rays with the back surface of the crystal. By using other asymmetric planes of the same crystal and rotating to selected angles, the spectrometer can operate with high resolution up to 50 keV.
Compensating for Nonlinear Effects in Coherent Detection Optical Transmission Systems
2012-01-01
Fiber nonlinearity is one of the most important limiters of capacity in coherent optical communications. In this paper, we review two nonlinear compensation methods： digital backward propagation （BP） and nonlinear electrical equalizer （NLEE） based on the timedomain Volterra series. These compensation algorithms are implemented in a singlechannel 50 Gb/s coherent optical singlecarrier frequency division multiplexed （CO-SCFDM） system transmitting over 10 × 80 km of standard singlemode fiber （SSMF）.
Zhurbenko, Vitaliy; Krozer, Viktor; Meincke, Peter
2007-01-01
A new broadband quarter-wavelength impedance transformer based on an asymmetric coupled line section is presented. The bandwidth of the coupled line transformer is extended with the help of an interconnecting transmission line. An analytical model for the transformer is developed. The analysis of...... the structure reveals that a fractional bandwidth of more than 100% at –20 dB reflection level can be achieved with such a structure. An experimental transformer circuit has been designed, fabricated and tested. Theoretical and experimental results are fair agreement and confirm the established theory....... The achieved bandwidth is almost 3 times larger as compared with standard matching circuits....
Ji, Ruonan; Wang, Shao-Wei; Liu, Xingxing; Lu, Wei
2016-04-01
In this paper, a three-layered sandwiched metamaterial is proposed to achieve giant and broadband asymmetric transmission of circularly polarized waves at the near-infrared communication band. The metamaterial consists of two layers of identical 45° tilted chiral S-shaped metasurfaces sandwiched with a subwavelength metallic grating. Based on the delicate combination of broadband polarization conversion and a cavity-enhanced effect, the asymmetric parameter can reach a maximum value of 0.87 and over 0.6 in a wide range from 1.2 to 2.0 μm, which has not been found in previous reports. Furthermore, a perfect robustness to misalignments is obtained as the effect originated from function-independent cascading cavities, which effectively reduce the requirement of alignment precision in layer-by-layer photolithography processes. The proposed nanostructure has a great potential to be used as a circular polarization rotator or diode-like device in optical communication systems.In this paper, a three-layered sandwiched metamaterial is proposed to achieve giant and broadband asymmetric transmission of circularly polarized waves at the near-infrared communication band. The metamaterial consists of two layers of identical 45° tilted chiral S-shaped metasurfaces sandwiched with a subwavelength metallic grating. Based on the delicate combination of broadband polarization conversion and a cavity-enhanced effect, the asymmetric parameter can reach a maximum value of 0.87 and over 0.6 in a wide range from 1.2 to 2.0 μm, which has not been found in previous reports. Furthermore, a perfect robustness to misalignments is obtained as the effect originated from function-independent cascading cavities, which effectively reduce the requirement of alignment precision in layer-by-layer photolithography processes. The proposed nanostructure has a great potential to be used as a circular polarization rotator or diode-like device in optical communication systems. Electronic supplementary
Kanno, Atsushi; Kuri, Toshiaki; Morohashi, Isao; Hosako, Iwao; Kawanishi, Tetsuya; Yoshida, Yuki; Kitayama, Ken-ichi
2015-02-01
Coherent terahertz signal transmission with multilevel modulation and demodulation is demonstrated using an optical sub-harmonic IQ mixer (SHIQM), which consists of optical components in advanced optical fiber communication technologies. An optical-frequency-comb-employed signal generator is capable of vector modulation as well as frequency tunability. Digital signal processing (DSP) adopted from the recently developed optical digital coherent communication can easily demodulate multi-level modulated terahertz signals by using electrical heterodyning for intermediate-frequency (IF) down conversion. This technique is applicable for mobile backhauling in the next-generation mobile communication technology directly connected to an optical fiber network as a high-speed wireless transmission link.
Asymmetric propagation of electromagnetic or elastic waves is important for control of the signal flow in various devices. Through mutual consistent theory analysis and numerical simulations to discuss the parity–time (PT) symmetry, we proposed and studied a linear silicon photonic device that shows asymmetric optical mode conversion. Remarkably, unidirectional mode conversion is observed at the threshold of breaking of the PT symmetry of our system. The corresponding theoretical analysis is expected to help design of chip-scale directional photonic devices. -- Highlights: ► We have designed a silicon-based optical waveguide with complex optical potential. ► In the waveguide, we observe a novel phenomenon of spontaneous PT symmetry breaking. ► It shows unidirectional mode conversion and one-way amplification of transmission. ► We have shown usual PT principles and rigorous theoretical analysis and discussion. ► This result may pave the way for the more exciting on-chip photonic devices.
S. Catalan
2016-01-01
Full Text Available Purpose. To compare the characteristics of asymmetric keratoconic eyes and normal eyes by Fourier domain optical coherence tomography (OCT corneal mapping. Methods. Retrospective corneal and epithelial thickness OCT data for 74 patients were compared in three groups of eyes: keratoconic (n=22 and normal fellow eyes (n=22 in patients with asymmetric keratoconus and normal eyes (n=104 in healthy subjects. Areas under the curve (AUC of receiver operator characteristic (ROC curves for each variable were compared across groups to indicate their discrimination capacity. Results. Three variables were found to differ significantly between fellow eyes and normal eyes (all p<0.05: minimum corneal thickness, thinnest corneal point, and central corneal thickness. These variables combined showed a high discrimination power to differentiate fellow eyes from normal eyes indicated by an AUC of 0.840 (95% CI: 0.762–0.918. Conclusions. Our findings indicate that topographically normal fellow eyes in patients with very asymmetric keratoconus differ from the eyes of healthy individuals in terms of their corneal epithelial and pachymetry maps. This type of information could be useful for an early diagnosis of keratoconus in topographically normal eyes.
Image transfer with spatial coherence for aberration corrected transmission electron microscopes.
Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi
2016-08-01
The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field's components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field's derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope. PMID:27155359
Ghantous M. Abou
2012-06-01
Full Text Available A model calculation is presented for the magnons coherent transmission and corresponding heat transport at magnetic insulating nanojunctions. The system consists of a ferromagnetically ordered ultrathin insulating junction between two semi-infinite ferromagnetically ordered leads. Spin dynamics are analyzed using the equations of motion for the spin precession displacements, valid for the range of temperatures of interest. Coherent scattering cross-sections at the junction boundary are calculated using the phase field matching theory, for all the incidence angles on the boundary from the lead bands, for arbitrary angles of incidence, at variable temperatures, and for different nano thicknesses of the ultrathin junction. The model is general; it is applied in particular to the Fe/Gd/Fe system with a sandwiched ferromagnetic Gd junction. It yields also the thermal conductivity due to the magnons coherent transmission between the two leads when these are maintained at slightly different temperatures. The calculation is carried out for state of the art values of the exchange constants, and elucidates the relation between the coherent scattering transmission of magnons and their thermal conductivity, for different thicknesses.
Dynamic control of coherent pulses via Fano-type interference in asymmetric double quantum wells
We study the temporal and spatial dynamics of two light pulses, a probe and a switch, propagating through an asymmetric double quantum well where tunneling-induced quantum interference may be observed. When such an interference takes place, in the absence of the switch, the quantum well is transparent to the probe which propagates over sufficiently long distances at very small group velocities. In the presence of a relatively strong switch, however, the probe pulse is absorbed due to the quenching of tunneling-induced quantum interference. The probe may be made to vanish even when switch and probe are somewhat delayed with respect to one another. Conversely, our asymmetric double quantum well may be rendered either opaque or transparent to the switch pulse. Such a probe-switch 'reciprocity' can be used to devise a versatile all-optical quantum interference-based solid-state switch for optical communication devices
Stefani, F; Stefani, Frank; Gerbeth, Gunter
2004-01-01
Using a mean-field dynamo model with a spherically symmetric helical turbulence parameter alpha which is dynamically quenched and disturbed by additional noise, the basic features of geomagnetic polarity reversals are shown to be generic consequences of the dynamo action in the vicinity of exceptional points of the spectrum. This simple paradigmatic model yields long periods of constant polarity which are interrupted by self-accelerating field decays leading to asymmetric polarity reversals. It shows the recently discovered bimodal field distribution, and it gives a natural explanation of the correlation between polarity persistence time and field strength. In addition, we find typical features of coherence resonance in the dependence of the persistence time on the noise.
Grebenyuk, Anton A.; Tarakanchikova, Yana V.; Ryabukho, Vladimir P.
2014-10-01
We propose an off-axis imaging approach for digital holographic microscopy (DHM) with quasimonochromatic partially spatially coherent illumination in transmission, which is intended to provide the advantages of off-axis partially coherent DHM imaging with a comparatively simple optical scheme. This approach does not require a diffraction grating for creating the off-axis modality and also allows for convenient control of the spatial frequency of carrier interference fringes for hologram sampling optimization. Theoretical analysis of the off-axis imaging process in this microscope is performed. An off-axis DHM based on the proposed approach is built and quantitative phase imaging of test objects is performed with suppressed coherent noise.
Photonic heterostructures with Levy-type disorder: statistics of coherent transmission
Fernandez-Marin, A A; Gopar, Victor A
2012-01-01
We study the electromagnetic transmission $T$ through one-dimensional (1D) photonic heterostructures whose random layer thicknesses follow a long-tailed distribution --L\\'evy-type distribution. Based on recent predictions made for 1D coherent transport with L\\'evy-type disorder, we show numerically that for a system of length $L$ (i) the average $ \\propto L^\\alpha$ for $0 \\propto L$ for $1\\le\\alpha$.
Analogical optical modeling of the asymmetric lateral coherence of betatron radiation.
Paroli, B; Chiadroni, E; Ferrario, M; Potenza, M A C
2015-11-16
By exploiting analogical optical modeling of the radiation emitted by ultrarelativistic electrons undergoing betatron oscillations, we demonstrate peculiar properties of the spatial coherence through an interferometric method reminiscent of the classical Young's double slit experiment. The expected effects due to the curved trajectory and the broadband emission are accurately reproduced. We show that by properly scaling the fundamental parameters for the wavelength, analogical optical modeling of betatron emission can be realized in many cases of broad interest. Applications to study the feasibility of future experiments and to the characterization of beam diagnostics tools are described. PMID:26698473
Transmission of a Serial 5.1-Tb/s Data Signal Using 16-QAM and Coherent Detection
Palushani, Evarist; Schmidt-Langhorst, Carsten; Richter, Thomas;
2011-01-01
Generation, transmission and coherent detection of a 640-GBd RZ-16-QAM, polarization-multiplexed OTDM signal is demonstrated. Considering 7% hard decision FEC overhead, error-free transmission of 4.8 Tb/s is achieved over 80-km dispersion-managed fiber.......Generation, transmission and coherent detection of a 640-GBd RZ-16-QAM, polarization-multiplexed OTDM signal is demonstrated. Considering 7% hard decision FEC overhead, error-free transmission of 4.8 Tb/s is achieved over 80-km dispersion-managed fiber....
Gliese, Ulrik Bo
1998-01-01
The principles of coherent fiber-optic links are presented and the transmission and signal processing capabilities offered to microwave and millimeter-wave systems are discussed. Furthermore, an overview of implemented transmitter types and link experiments is given......The principles of coherent fiber-optic links are presented and the transmission and signal processing capabilities offered to microwave and millimeter-wave systems are discussed. Furthermore, an overview of implemented transmitter types and link experiments is given...
Phase field modeling of a glide dislocation transmission across a coherent sliding interface
Zheng, Songlin; Ni, Yong; He, Linghui
2015-04-01
Three-dimensional phase field microelasticity modeling and simulation capable of representing core structure and elastic interactions of dislocations are used to study a glide dislocation transmission across a coherent sliding interface in face-centered cubic metals. We investigate the role of the interface sliding process, which is described as the reversible motion of interface dislocation on the interfacial barrier strength to transmission. Numerical results show that a wider transient interface sliding zone develops on the interface with a lower interfacial unstable stacking fault energy to trap the glide dislocation leading to a stronger barrier to transmission. The interface sliding zone shrinks in the case of high applied stress and low mobility for the interfacial dislocation. This indicates that such interfacial barrier strength might be rate dependent. We discuss the calculated interfacial barrier strength for the Cu/Ni interface from the contribution of interface sliding comparable to previous atomistic simulations.
Coherent light transmission properties of commercial photonic crystal hollow core optical fiber.
Cranch, G A; Miller, G A
2015-11-01
Photonic crystal hollow core fiber (PC-HCF) has enabled many exciting new applications in nonlinear optics and spectroscopy. However, to date there has been less impact in coherent applications where preservation of optical phase over long fiber lengths is crucial. This paper presents characteristics of three commercially available PC-HCFs relevant to coherent applications including higher-order mode analysis, birefringence and polarization-dependent loss, and their impact on coherent light transmission in PC-HCF. Multipath interference due to higher-order mode propagation and Fresnel reflection is shown to generate excess intensity noise in transmission, which can be suppressed by up to 20 dB through high frequency phase modulation of the source laser. To demonstrate the potential of PC-HCF in high performance sensing, a Mach-Zehnder interferometer (MZI) incorporating 10 m of PC-HCF in each arm is characterized and demonstrates a phase resolution (59×10(-9) rad/Hz(1/2) at 30 kHz) close to the shot noise limit, which is better than can be achieved in a MZI made with the same length of single mode solid core fiber because of the limit set by fundamental thermodynamic noise (74×10(-9) rad/Hz(1/2) at 30 kHz). PMID:26560626
Oba, Roger; Finette, Steven
2002-02-01
Results of a computer simulation study are presented for acoustic propagation in a shallow water, anisotropic ocean environment. The water column is characterized by random volume fluctuations in the sound speed field that are induced by internal gravity waves, and this variability is superimposed on a dominant summer thermocline. Both the internal wave field and resulting sound speed perturbations are represented in three-dimensional (3D) space and evolve in time. The isopycnal displacements consist of two components: a spatially diffuse, horizontally isotropic component and a spatially localized contribution from an undular bore (i.e., a solitary wave packet or solibore) that exhibits horizontal (azimuthal) anisotropy. An acoustic field is propagated through this waveguide using a 3D parabolic equation code based on differential operators representing wide-angle coverage in elevation and narrow-angle coverage in azimuth. Transmission loss is evaluated both for fixed time snapshots of the environment and as a function of time over an ordered set of snapshots which represent the time-evolving sound speed distribution. Horizontal acoustic coherence, also known as transverse or cross-range coherence, is estimated for horizontally separated points in the direction normal to the source-receiver orientation. Both transmission loss and spatial coherence are computed at acoustic frequencies 200 and 400 Hz for ranges extending to 10 km, a cross-range of 1 km, and a water depth of 68 m. Azimuthal filtering of the propagated field occurs for this environment, with the strongest variations appearing when propagation is parallel to the solitary wave depressions of the thermocline. A large anisotropic degradation in horizontal coherence occurs under the same conditions. Horizontal refraction of the acoustic wave front is responsible for the degradation, as demonstrated by an energy gradient analysis of in-plane and out-of-plane energy transfer. The solitary wave packet is
Mounaix, Mickael; Andreoli, Daria; Defienne, Hugo; Volpe, Giorgio; Katz, Ori; Grésillon, Samuel; Gigan, Sylvain
2016-06-01
We report the broadband characterization of the propagation of light through a multiple scattering medium by means of its multispectral transmission matrix. Using a single spatial light modulator, our approach enables the full control of both the spatial and spectral properties of an ultrashort pulse transmitted through the medium. We demonstrate spatiotemporal focusing of the pulse at any arbitrary position and time with any desired spectral shape. Our approach opens new perspectives for fundamental studies of light-matter interaction in disordered media, and has potential applications in sensing, coherent control, and imaging.
By employing a nondeterministic noiseless linear amplifier, we propose to increase the maximum transmission distance of continuous-variable quantum key distribution with noisy coherent states. With the covariance matrix transformation, the expression of secret key rate under reverse reconciliation is derived against collective entangling cloner attacks. We show that the noiseless linear amplifier can compensate the detrimental effect of the preparation noise with an enhancement of the maximum transmission distance and the noise resistance. - Highlights: • Noiseless amplifier is applied in noisy coherent state quantum key distribution. • Negative effect of preparation noise is compensated by noiseless amplification. • Maximum transmission distance and noise resistance are both enhanced
Just like an electronic diode that allows the electrical current to flow in one direction only, a kind of chiral metamaterial structure with a similar functionality for the electromagnetic wave is proposed. The designed nanostructure that consists of twisted metallic split-ring resonators on both sides of a dielectric substrate achieves asymmetric transmission for a forward and backward propagating linearly polarized wave by numerical simulation in near-infrared band. Difference in transmission efficiency of the optimized structure between the same polarized waves incident from opposite directions can reach a maximum at the communication wavelength (1.55 μm). Moreover, the simulation results of this structure also exhibit strong optical activity and circular dichroism. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Naghdi Yazdan
2015-08-01
Full Text Available Given the recent fluctuation in the exchange rate and the presence of several factors such as the various economy-political sanctions (mainly embargos on oil and banking, extreme volatility in different economic fields, and consequently the devaluation of national and public procurement -A landmark that is emanating from exchange rate fluctuation - two points should be noted: First, it is essential to review the effect of exchange rate fluctuation on macro economic variables such as inflation and to provide appropriate policies. Second, the existence of this condition provides the chance to study the relation between exchange rate and inflation in a non-linear and asymmetric method. Hence, the present study seeks to use TAR model and, on the basis of monthly time series data over the period March 2002 to March 2014, to analyze the cross-asymmetric and non-linear exchange rate on consumer price index (CPI in Iran. The results also show the presence of an asymmetric long-term relationship between these variables (exchange rate and CPI. Also, in the Iranian economy, the effect of negative shocks of exchange rate on inflation is more sustainable than the one from positive shocks.
Optical radio-photonic channel for transmission of a coherent narrowband analog signal
Zhuk, D. I.; Denisyuk, I. Yu.; Fokina, M. I.
2015-10-01
The channel of an optical transmission line of coherent narrowband analog signal consisting of a continuous-wave laser, an electro-optic modulator, and a vector phase rotator based on electrically controlled fiber-optical 1 × 2 splitter and fixed delay lines is analyzed. The scheme is constructed from commercially available components used in digital optical communication systems. The applicability of components for analog and small-signal circuits is determined. Variation of radio signal phase in the range from 0° to 170° for radio signal frequencies between 1 and 2 GHz is demonstrated experimentally. It is shown that phase variation is a linear function of frequency in this range.
张解放; 刘宇陆
2002-01-01
This article is concerned with the extended homogeneous balance method for studying the abundant lacalized solution structure of the (2+1)-dimensional asymmetric Nizhnik-novikov-Veselov equation.A Baecklund transformation was first obtained.and then the richness of the localized coherent structures was found,which was caused by the entrance of two variable-separated arbitrary functions,in the model.For some spectial choices of the arbitrary functions,it is shown that the localized structures of the model may be dromions,lumps,and rinmg solitons.
Incomplete, slow, and asymmetric price transmission in ten product markets of Bolivia
Varela, Gonzalo J.
2012-01-01
With food prices on the rise, understanding the transmission of price shocks, both internationally and domestically, is central for trade policy analysis. This paper examines spatial market integration and its determinants for ten key food products in Bolivia, across the four most important cities, and with the world, over the period 1991-2008. Within Bolivia, markets for onions, chicken, ...
Novitsky, Andrey V; Zhukovsky, Sergei V
2010-01-01
The electronic Lorentz theory is employed to determine the electromagnetic response of planar split-ring metamaterials. Starting from the dynamics of individual free carriers, the effective permittivity tensor of the metamaterial is calculated. Whenever the split ring lacks in-plane mirror symmetry, the corresponding permit- tivity tensor has a crystallographic structure of an elliptically dichroic medium, and the metamaterial exhibits optical properties of planar chiral structures. Its transmission spectra are different for right-handed vs. left- handed circular polarization of the incident wave, so the structure changes its transmittance when the direction of incidence is reversed. The magnitude of this change is shown to be related to the geometric parameters of the split ring. The proposed approach can be straightforwardly generalized to a wide variety of metal-dielectric metamaterial geometries.
Unrepeatered field transmission of 2 Tbit/s multi-banded coherent WDM over 124 km of installed SMF.
Frascella, Paola; Mac Suibhne, Naoise; Gunning, Fatima C Garcia; Ibrahim, Selwan K; Gunning, Paul; Ellis, Andrew D
2010-11-22
In this paper we report field transmission of a 2 Tbit/s multi-banded Coherent WDM signal over BT Ireland's installed SMF, using EDFA amplification only, with mixed Ethernet (with FEC) and PRBS payloads. To the best of our knowledge, the results obtained represent the highest total capacity transmitted over installed SMF with orthogonal subcarriers. BERs below 10(-5) and no frame-loss were recorded for all 49 subcarriers. Extended BER measurements over several hours showed fluctuations that can be attributed to PMD and to dynamic effects associated with clock instabilities. PMID:21164822
Taniman, Robert; Meijerink, Arjan; Etten, van Wim; Haartsen, Jaap
2003-01-01
A Radio over Fiber (RoF) distribution network based on single-mode fiber (SMF) and a combination of coherence multiplexing (CM) and subcarrier multiplexing (SCM) is proposed. CM is a relatively unknown and potentially inexpensive form of photonic code-division multiplexing, and is used here as a mea
Iglesias Olmedo, Miguel; Pang, Xiaodan; Schatz, Richard;
2015-01-01
We discuss about digital signal processing approaches that can enable coherent links based on semiconductor lasers. A state-of-the art analysis on different carrier-phase recovery (CPR) techniques is presented. We show that these techniques are based on the assumption of lorentzian linewidth, which...
Polarization assisted fast data encoding and transmission using coherence based spectral anomalies
Two methods for fast information encoding and free space communication are proposed, which are based on the rapid transitions in coherence-based (spatial and temporal) spectral anomalies called ‘spectral switches’. The information (data bits) could be encoded in terms of red and blue shifts in the source spectrum. The encoding process itself could be made fast by polarization assisted switching of spectral anomalies using a polarization selective device such as an electro-optic modulator. The advantages and limitations of this polarization based data processing mechanism are also discussed. (paper)
The brightness and interference fringes of a spin-polarized electron beam extracted from a semiconductor photocathode excited by laser irradiation are directly measured via its use in a transmission electron microscope. The brightness was 3.8 × 107 A cm−2 sr−1 for a 30-keV beam energy with the polarization of 82%, which corresponds to 3.1 × 108 A cm−2 sr−1 for a 200-keV beam energy. The resulting electron beam exhibited a long coherence length at the specimen position due to the high parallelism of (1.7 ± 0.3) × 10−5 rad, which generated interference fringes representative of a first-order correlation using an electron biprism. The beam also had a high degeneracy of electron wavepacket of 4 × 10−6. Due to the high polarization, the high degeneracy and the long coherence length, the spin-polarized electron beam can enhance the antibunching effect
Bertrand, Yoann; Blay-Fornarino, Mireille; Boudaoud, Karima; Riveill, Michel
2016-01-01
In order to protect resources from unauthorized access and data leakage in companies, security experts and administrators can use mechanisms such as Access Control (AC) and Transmission Control (TC). Both AC and TC are based on policies that are defined, modified and revoked by these experts. However, policy management can be a time-consuming and tiresome task, especially when both mechanisms are used on large sets of users and resources. Moreover, contradictions between AC and TC policies ca...
张解放; 刘宇陆
2002-01-01
This article is concerned with the extended homogeneous balance method for studying the abundant localized solution structure of the (2 + 1)-dimensional asymmetric Nizhnik-Novikov-Veselov equation. A Backlund transformation was first obtained, and then the richness of the localized coherent structures was found, which was caused by the entrance of two variable-separated arbitrary functions, in the model. For some special choices of the arbitrary functions, it is shown that the localized structures of the model may be dromions, lumps, and ring solitons.
Moharram Ainollahi
2015-09-01
Full Text Available I n this paper asymmetric price transmission mechanism and nonlinear adjustment between producer and retail prices of milk were examined in Zanjan Province of Iran. For this purpose, a Two-Regime Threshold Vector Error Correction Model (TVECM and a Sup-LM Test developed by Hansen and Seo (2002 were employed for checking presence of a threshold effect. Application of unit root tests indicated that both wholesale and retail prices are I (1, and Johansen test verified cointegration of the series in the long-run. Results of the Sup-LM test confirmed threshold adjustment of product price towards the long-run equilibrium. Furthermore, results obtained from TVECM revealed that the coefficient of ECT is significant only in the first regime of retailing equation implying that retailers significantly respond to the decreasing deviations from the long-run equilibrium. While adjustment coefficient is not significant for wholesale equation in both regimes to imply that there is not significant inclination to react to deviations from the long-run equilibrium among the wholesalers despite the retailers.
Lazarou, I.; Spatharakis, C.; Katopodis, V.; Dris, S.; Bakopoulos, P.; Schrenk, B.; Avramopoulos, H.
2013-12-01
We demonstrate a flexible multi-format vector modulator for coherent passive optical network (PON) architectures based on a non-interferometric cascade of a Semiconductor Optical Amplifier (SOA) and an Electro-Absorption Modulator (EAM) that exhibits increased simplicity and high energy-efficiency at low cost. 12- and 16- Quadrature Amplitude Modulation (QAM) constellations are generated, achieving modulation efficiencies of 3.6 and 4 bits/symbol respectively. The presented results demonstrate successful transmission over 25 km of fiber below the Forward Error Correction (FEC) limit, with sufficient compatible loss-budgets, making the proposed modulator concept an attractive candidate for urban network deployments, where high user density demands spectrally efficient formats. In addition, we describe the operation principle of the proposed modulator in detail and finally, the complete set of the digital signal processing (DSP) functionalities and algorithms that follow the standard coherent detection scheme is given, emphasizing on novel methods for QAM signal demodulation with uncommon constellation diagrams.
Loudon, J. C.; Yazdi, Sadegh; Kasama, Takeshi; Zhigadlo, N. D.; Karpinski, J.
2015-01-01
We demonstrate that images of flux vortices in a superconductor taken with a transmission electron microscope can be used to measure the penetration depth and coherence length in all directions at the same temperature and magnetic field. This is particularly useful for MgB2, where these quantities...... vary with the applied magnetic field and values are difficult to obtain at low field or in the c direction. We obtained images of flux vortices from a MgB2 single crystal cut in the ac plane by focused ion beam milling and tilted to 45 degrees. with respect to the electron beam about the...... crystallographic a axis. A new method was developed to simulate these images that accounted for vortices with a nonzero core in a thin, anisotropic superconductor and a simplex algorithm was used to make a quantitative comparison between the images and simulations to measure the penetration depths and coherence...
Beppu, Shohei; Kasai, Keisuke; Yoshida, Masato; Nakazawa, Masataka
2015-02-23
We describe a 2048 QAM single-carrier coherent optical transmission over 150 km in detail. The OSNR at the transmitter was increased by 5 dB and the phase noise at the receiver was reduced from 0.35 to 0.17 degrees compared with a previous 1024 QAM transmission. Furthermore, we employed an A/D converter with a higher ENOB (7 bit) to guarantee the SNR of the digital QAM data, and introduced a polarization-demultiplexing algorithm to fast track the polarization state transition. As a result, a 66 Gbit/s polarization-multiplexed 2048 QAM signal was successfully transmitted within an optical bandwidth of 3.6 GHz including a pilot tone, and a potential SE of 15.3 bit/s/Hz under a 20% FEC overhead was achieved. PMID:25836531
赵瑞娟; 安盼龙; 许丽萍; 杨艳
2012-01-01
非对称多势垒可获得比双势垒更大的共振隧穿电流及更良好的峰谷比。通过分析单电子对任意势垒透射的理论模型,建立了任意非对称三势垒模型,研究了不同偏压和温度对透射系数的影响,并得出结论,为进一步设计非对称量子器件提供理论指导。%Asymmetric multi-barrier can obtain larger resonant tunneling current and better peak-valley ratio than double barrier. By analyzing the theoretical models of single-electron transmission on any harrier, an arbitrary asymmetric three-barrier model was established. Effects of different bias and temperatures on the transmission coefficient were studied. It provides a theoretical guidance for the further design of asymmetric quantum devices.
Frédéric Landmann; Odile Bain; Coralie Martin; Shigehiko Uni; Taylor, Mark J.; William Sullivan
2012-01-01
Summary Parasitic filarial nematodes that belong to the Onchocercidae family live in mutualism with Wolbachia endosymbionts. We developed whole-mount techniques to follow the segregation patterns of Wolbachia through the somatic and germline lineages of four filarial species. These studies reveal multiple evolutionarily conserved mechanisms that are required for Wolbachia localization to the germline. During the initial embryonic divisions, Wolbachia segregate asymmetrically such that they...
Quantum correlation via quantum coherence
Yu, Chang-shui; Zhang, Yang; Zhao, Haiqing
2014-01-01
Quantum correlation includes quantum entanglement and quantum discord. Both entanglement and discord have a common necessary condition--------quantum coherence or quantum superposition. In this paper, we attempt to give an alternative understanding of how quantum correlation is related to quantum coherence. We divide the coherence of a quantum state into several classes and find the complete coincidence between geometric (symmetric and asymmetric) quantum discords and some particular classes ...
Itoi, Miho; Jike, Toyoharu; Nishio-Hamane, Daisuke; Udagawa, Seiichi; Tsuda, Tetsuya; Kuwabata, Susumu; Boukheddaden, Kamel; Andrus, Matthew J; Talham, Daniel R
2015-11-25
The local structure within the Co-Fe atomic array of the photoswitchable coordination polymer magnet, K0.3Co[Fe(CN)6]0.77·nH2O, is directly observed during charge transfer induced spin transition (CTIST), a solid-solid phase change, using high-resolution transmission electron microscopy (HRTEM). Along with the low-spin (LS) or thermally quenched high-spin (HS) states normally observed in CTIST solids at low temperature, slow cooling of K0.3Co[Fe(CN)6]0.77·nH2O results in an intermediate phase containing both HS and LS domains with short coherence length. By mapping individual metal-metal distances, the nanometer-scale HS domains are directly visualized within the LS array. Temperature-dependent analyses allow monitoring of HS domain coarsening along the warming branch of the CTIST, providing direct visualization of the elastic process and insight into the mechanism of phase propagation. Normally sensitive to electron beam damage, the low-temperature TEM measurements of the porous coordination polymer are enabled by using appropriate ionic liquids instead of usual conductive thin-film coatings, an approach that should find general utility in related classes of materials. PMID:26510096
Morrison, James
1984-01-01
Asymmetric Synthesis, Volume 4: The Chiral Carbon Pool and Chiral Sulfur, Nitrogen, Phosphorus, and Silicon Centers describes the practical methods of obtaining chiral fragments. Divided into five chapters, this book specifically examines initial chiral transmission and extension. The opening chapter describes the so-called chiral carbon pool, the readily available chiral carbon fragments used as building blocks in synthesis. This chapter also provides a list of 375 chiral building blocks, along with their commercial sources, approximate prices, and methods of synthesis. Schemes involving
Cheng, Yun; Tan, Jun; Liu, Liu; He, Jing; Tang, Jin; Chen, Lin; Zhang, Jun; Li, Qiang; Xiao, Minlei
2016-02-01
To improve the performance of channel estimation (CE), a method of joint frame synchronization and data-aided CE using less training overhead is proposed. A 100-Gb/s polarization-division multiplexing coherent transmission system with quaternary phase-shift keying based on the proposed method is demonstrated by simulation. The simulation results show that the proposed method could achieve accurate timing offset and CE in the presence of strong amplified spontaneous emission noise.
Frédéric Landmann
2012-04-01
Parasitic filarial nematodes that belong to the Onchocercidae family live in mutualism with Wolbachia endosymbionts. We developed whole-mount techniques to follow the segregation patterns of Wolbachia through the somatic and germline lineages of four filarial species. These studies reveal multiple evolutionarily conserved mechanisms that are required for Wolbachia localization to the germline. During the initial embryonic divisions, Wolbachia segregate asymmetrically such that they concentrate in the posteriorly localized P2 blastomere, a precursor to the adult germline and hypodermal lineages. Surprisingly, in the next division they are excluded from the germline precursor lineage. Rather, they preferentially segregate to the C blastomere, a source of posterior hypodermal cells. Localization to the germline is accomplished by a distinct mechanism in which Wolbachia invade first the somatic gonadal cells close to the ovarian distal tip cell, the nematode stem cell niche, from the hypodermis. This tropism is associated with a cortical F-actin disruption, suggesting an active engulfment. Significantly, germline invasion occurs only in females, explaining the lack of Wolbachia in the male germline. Once in the syncytial environment of the ovaries, Wolbachia rely on the rachis to multiply and disperse into the germ cells. The utilization of cell-to-cell invasion for germline colonization may indicate an ancestral mode of horizontal transfer that preceded the acquisition of the mutualism.
Coherent soliton communication lines
Yushko, O. V., E-mail: olesya.yushko@gmail.com; Redyuk, A. A.; Fedoruk, M. P.; Turitsyn, S. K. [Novosibirsk State University (Russian Federation)
2014-11-15
The data transmission in coherent fiber-optical communication lines using solitons with a variable phase is studied. It is shown that nonlinear coherent structures (solitons) can be applied for effective signal transmission over a long distance using amplitude and optical-phase keying of information. The optimum ratio of the pulse width to the bit slot at which the spectral efficiency (transmitted bits per second and hertz) is maximal is determined. It is shown that soliton fiber-optical communication lines can ensure data transmission at a higher spectral efficiency as compared to traditional communication lines and at a high signal-to-noise ratio.
李鹏云; 陈波; 张峰; 王干军; 宋春芳
2012-01-01
研究了不对称导线对输电转角塔动力特性的影响.首先基于空间杆系有限元理论建立了输电转角塔的力学模型.然后基于空间索单元建立了输电导线的力学模型.在此基础上组集形成输电塔线耦连体系分析模型.以中国某大跨度输电转角塔为实际工程背景,基于有限元方法考察了该结构的塔线耦连振动效应.进一步进行导线影响的参数研究,考察了相邻导线对输电塔本身振动特性的影响.结果表明,输电转角塔的塔线耦连效应显著,结构的扭转振型受到导线的影响非常显著.因此在转角塔的设计建造过程中,应当充分考虑到导线参数的影响.%The effects of asymmetric cables on the dynamic characteristics of transmission angle-tower are actively investigated in this study. The mechanical model of the transmission angle-tower and cables are developed based on the spatial member finite element approach. The coupling vibration model of the transmission tower-line system is constructed for further analysis. A real long span transmission angle tower system is taken as an example to examine the properties of the dynamic coupling effects based on finite element method. The parametric study is carried out to examine the effects of the cable on the dynamic properties of the angle tower. The made observations indicate that the dynamic coupling effects of the tower and cables are obvious and the rotational modes of the tower are substantially affected by the cables. The influence of the cables on the transmission angle tower should be taken into consideration in the structural design and construction.
The study of CP violation in beauty decay is one of the key challenges facing high energy physics. Much work has not yielded a definitive answer how this study might best be performed. However, one clear conclusion is that new accelerator facilities are needed. Proposals include experiments at asymmetric electron-positron colliders and in fixed-target and collider modes at LHC and SSC. Fixed-target and collider experiments at existing accelerators, while they might succeed in a first observation of the effect, will not be adequate to study it thoroughly. Giomataris has emphasized the potential of a new approach to the study of beauty CP violation: the asymmetric proton collider. Such a collider might be realized by the construction of a small storage ring intersecting an existing or soon-to-exist large synchrotron, or by arranging collisions between a large synchrotron and its injector. An experiment at such a collider can combine the advantages of fixed-target-like spectrometer geometry, facilitating triggering, particle identification and the instrumentation of a large acceptance, while the increased √s can provide a factor > 100 increase in beauty-production cross section compared to Tevatron or HERA fixed-target. Beams crossing at a non-zero angle can provide a small interaction region, permitting a first-level decay-vertex trigger to be implemented. To achieve large √s with a large Lorentz boost and high luminosity, the most favorable venue is the high-energy booster (HEB) at the SSC Laboratory, though the CERN SPS and Fermilab Tevatron are also worth considering
欧阳键; 庄毅; 薛羽; 王洲
2013-01-01
The application of unmanned aerial vehicles (UAVs) in relay transmission systems has received more and more attention recently. This paper presents a study of a UAV relay transmission system over asymmetric fading channels. Using the maximization of the output signal-to-noise ratio as the design criterion, the optimal beamforming (BF) for the relay system is first obtained. Then, the new accurate expressions for the outage probability, ergodic capacity and average symbol error rate are all derived. Finally, computer simulations demonstrate the validity of the proposed relay transmission scheme and its performance analysis, and provide a quantitative study of the effect of antenna number, channel parameters and power allocation on system performance. Our work can provide some useful reference and foundation work to the system engineer for the purpose of designing a UAV relay transmission system and evaluating its performance.%无人机(UAV)作为中继传输平台受到了国内外研究人员的广泛关注.本文研究了非对称衰落信道下的无人机中继传输系统,提出了输出信噪比最大化准则下的波束形成(BF)优化方案,并推导出系统中断概率、遍历容量和平均误符号率等无线通信系统主要性能指标的理论表达式.通过计算机仿真验证了本文提出的中继传输方案及性能分析的正确性,并定量分析了天线数量、信道参数以及功率分配对系统性能的影响,为无人机中继传输系统的设计及性能评估提供了参考和依据.
Liu, Weilin; Yao, Jianping
2013-10-01
A novel scheme to simultaneously provide UWB, 60-GHz millimeter-wave (mmW), and baseband services over a wavelength division multiplexing (WDM) passive optical network (PON) is proposed and demonstrated. In the proposed system, an OOK Gaussian pulse signal is modulated on the optical carrier and then converted to an OOK UWB impulse signal at an edge filter, a baseband signal and a 30-GHz signal are then modulated on the same optical carrier. By employing polarization multiplex technique, the UWB and baseband signal will have orthogonal polarization directions and the spectrum interference between the two signals is avoided. By suppressing the optical carrier, a frequencydoubled mmW signal at 60 GHz is generated by beating the two 1st order sidebands at a photodetector (PD). Error-free transmission of a UWB signal at 2.5 Gbps and a wired baseband signal at 2.5 and 5 Gbps over a 25-km single-mode fiber (SMF) is achieved. A frequency-doubled mmW signal at 60 GHz is also obtained.
The Scalable Coherent Interface (IEEE P1596) is establishing an interface standard for very high performance multiprocessors, supporting a cache-coherent-memory model scalable to systems with up to 64K nodes. This Scalable Coherent Interface (SCI) will supply a peak bandwidth per node of 1 GigaByte/second. The SCI standard should facilitate assembly of processor, memory, I/O and bus bridge cards from multiple vendors into massively parallel systems with throughput far above what is possible today. The SCI standard encompasses two levels of interface, a physical level and a logical level. The physical level specifies electrical, mechanical and thermal characteristics of connectors and cards that meet the standard. The logical level describes the address space, data transfer protocols, cache coherence mechanisms, synchronization primitives and error recovery. In this paper we address logical level issues such as packet formats, packet transmission, transaction handshake, flow control, and cache coherence. 11 refs., 10 figs
Zhu, Meng-Zheng; Ye, Liu
2015-04-01
An efficient scheme is proposed to implement a quantum cloning machine in separate cavities based on a hybrid interaction between electron-spin systems placed in the cavities and an optical coherent pulse. The coefficient of the output state for the present cloning machine is just the direct product of two trigonometric functions, which ensures that different types of quantum cloning machine can be achieved readily in the same framework by appropriately adjusting the rotated angles. The present scheme can implement optimal one-to-two symmetric (asymmetric) universal quantum cloning, optimal symmetric (asymmetric) phase-covariant cloning, optimal symmetric (asymmetric) real-state cloning, optimal one-to-three symmetric economical real-state cloning, and optimal symmetric cloning of qubits given by an arbitrary axisymmetric distribution. In addition, photon loss of the qubus beams during the transmission and decoherence effects caused by such a photon loss are investigated.
Experimental evidence of coherent transport.
Flores-Olmedo, E; Martínez-Argüello, A M; Martínez-Mares, M; Báez, G; Franco-Villafañe, J A; Méndez-Sánchez, R A
2016-01-01
Coherent transport phenomena are difficult to observe due to several sources of decoherence. For instance, in the electronic transport through quantum devices the thermal smearing and dephasing, the latter induced by inelastic scattering by phonons or impurities, destroy phase coherence. In other wave systems, the temperature and dephasing may not destroy the coherence and can then be used to observe the underlying wave behaviour of the coherent phenomena. Here, we observe coherent transmission of mechanical waves through a two-dimensional elastic Sinai billiard with two waveguides. The flexural-wave transmission, performed by non-contact means, shows the quantization when a new mode becomes open. These measurements agree with the theoretical predictions of the simplest model highlighting the universal character of the transmission fluctuations. PMID:27121226
Experimental evidence of coherent transport
Flores-Olmedo, E.; Martínez-Argüello, A. M.; Martínez-Mares, M.; Báez, G.; Franco-Villafañe, J. A.; Méndez-Sánchez, R. A.
2016-01-01
Coherent transport phenomena are difficult to observe due to several sources of decoherence. For instance, in the electronic transport through quantum devices the thermal smearing and dephasing, the latter induced by inelastic scattering by phonons or impurities, destroy phase coherence. In other wave systems, the temperature and dephasing may not destroy the coherence and can then be used to observe the underlying wave behaviour of the coherent phenomena. Here, we observe coherent transmission of mechanical waves through a two-dimensional elastic Sinai billiard with two waveguides. The flexural-wave transmission, performed by non-contact means, shows the quantization when a new mode becomes open. These measurements agree with the theoretical predictions of the simplest model highlighting the universal character of the transmission fluctuations. PMID:27121226
2006-11-01
that oscillate in certain directions. Reflection or scattering of light favours certain orientations of the electric and magnetic fields over others. This is why polarising sunglasses can filter out the glint of sunlight reflected off a pond. When light scatters through the expanding debris of a supernova, it retains information about the orientation of the scattering layers. If the supernova is spherically symmetric, all orientations will be present equally and will average out, so there will be no net polarisation. If, however, the gas shell is not round, a slight net polarisation will be imprinted on the light. This is what broad-band polarimetry can accomplish. If additional spectral information is available ('spectro-polarimetry'), one can determine whether the asymmetry is in the continuum light or in some spectral lines. In the case of the Type Ia supernovae, the astronomers found that the continuum polarisation is very small so that the overall shape of the explosion is crudely spherical. But the much larger polarization in strongly blue-shifted spectral lines evidences the presence, in the outer regions, of fast moving clumps with peculiar chemical composition. "Our study reveals that explosions of Type Ia supernovae are really three-dimensional phenomena," says Dietrich Baade. "The outer regions of the blast cloud is asymmetric, with different materials found in 'clumps', while the inner regions are smooth." "This study was possible because polarimetry could unfold its full strength thanks to the light-collecting power of the Very Large Telescope and the very precise calibration of the FORS instrument," he adds. The research team first spotted this asymmetry in 2003, as part of the same observational campaign (ESO PR 23/03 and ESO PR Photo 26/05). The new, more extensive results show that the degree of polarisation and, hence, the asphericity, correlates with the intrinsic brightness of the explosion. The brighter the supernova, the smoother, or less clumpy
Selective coherent perfect absorption in metamaterials
We show multi-band coherent perfect absorption (CPA) in simple bilayered asymmetrically split ring metamaterials. The selectivity of absorption can be accomplished by separately excited electric and magnetic modes in a standing wave formed by two coherent counterpropagating beams. In particular, each CPA can be completely switched on/off by the phase of a second coherent wave. We propose a practical scheme for realizing multi-band coherent perfect absorption of 100% that is allowed to work from microwave to optical frequency
Yamilov, A; Sarma, R; Cao, H
2015-01-01
The universal bimodal distribution of transmission eigenvalues in lossless diffusive systems un- derpins such celebrated phenomena as universal conductance fluctuations, quantum shot noise in condensed matter physics and enhanced transmission in optics and acoustics. Here, we show that in the presence of absorption, density of the transmission eigenvalues depends on the confinement geometry of scattering media. Furthermore, in an asymmetric waveguide, densities of the reflection and absorption eigenvalues also depend of the side from which the waves are incident. With increas- ing absorpotion, the density of absorption eigenvalues transforms from single-peak to double-peak function. Our findings open a new avenue for coherent control of wave transmission, reflection and absorption in random media.
Coherent states for quadratic Hamiltonians
Contreras-Astorga, Alonso; Velazquez, Mercedes
2010-01-01
The coherent states for a set of quadratic Hamiltonians in the trap regime are constructed. A matrix technique which allows to identify directly the creation and annihilation operators will be presented. Then, the coherent states as simultaneous eigenstates of the annihilation operators will be derived, and they are going to be compared with those attained through the displacement operator method. The corresponding wave function will be found, and a general procedure for obtaining several expected values involving the canonical operators in these states will be described. The results will be illustrated through the asymmetric Penning trap.
Coherent states for quadratic Hamiltonians
Contreras-Astorga, Alonso; Fernandez C, David J; Velazquez, Mercedes, E-mail: david@fis.cinvestav.mx [Departamento de Fisica, Cinvestav, AP 14-740, 07000 Mexico DF (Mexico)
2011-01-21
The coherent states for a set of quadratic Hamiltonians in the trap regime are constructed. A matrix technique which allows us to directly identify the creation and annihilation operators will be presented. Then, the coherent states as simultaneous eigenstates of the annihilation operators will be derived, and will be compared with those attained through the displacement operator method. The corresponding wavefunction will be found, and a general procedure for obtaining several mean values involving the canonical operators in these states will be described. The results will be illustrated through the asymmetric Penning trap.
Hsu, Liang-Yan; Rabitz, Herschel
2015-07-01
We introduce a tunneling effect by a driving field, referred to as coherent revival of tunneling (CRT), corresponding to complete tunneling (transmission coefficient =1 ) that is revived from the circumstance of total reflection (transmission coefficient ≈0 ) through application of an appropriate perpendicular high-frequency ac field. To illustrate CRT, we simulate electron transport through fish-bone-like quantum-dot arrays by using single-particle Green's functions along with Floquet theory, and we explore the corresponding current-field amplitude characteristics as well as current-polarization characteristics. In regard to the two characteristics, we show that CRT exhibits entirely different features than coherent destruction of tunneling and photon-assisted tunneling. We also discuss two practical conditions for experimental realization of CRT.
Asymmetric-Structure Analysis of Carbon and Energy Markets
Xu, Wei; Cao, Guangxi
2016-02-01
This study aimed to investigate the asymmetric structure between the carbon and energy markets from two aspects of different trends (up or down) and volatility-transmission direction using asymmetric detrended cross-correlation analysis (DCCA) cross-correlation coefficient test, multifractal asymmetric DCCA (MF-ADCCA) method, asymmetric volatility-constrained correlation metric and time rate of information-flow approach. We sampled 1283 observations from January 2008 to December 2012 among pairs of carbon and energy markets for analysis. Empirical results show that the (1) asymmetric characteristic from the cross-correlation between carbon and returns in the energy markets is significant, (2) asymmetric cross-correlation between carbon and energy market price returns is persistent and multifractral and (3) volatility of the base assets of energy market returns is more influential to the base asset of the carbon market than that of the energy market.
Weng, Yi; Pan, Zhongqi
2016-02-01
For next-generation long-haul communication systems, space-division multiplexing (SDM) is suggested as a promising technique for providing orders of magnitude increase in transmission capacity. Optical amplifiers for multimode fibers are the crucial components to realize SDM systems, while few-mode fiber (FMF) has the advantage of strong intensity overlap between different modes that allows sharing of single pump across multiple signal modes. FMF-based erbiumdoped fiber amplifiers (FM-EDFA) have been intensively studied. Since SDM is exceedingly reliant on DSP technique and thus has more stringent requirement on noise performance, FMF-based distributed Raman amplifier (FM-DRA) benefits from relatively lower noise figure (NF) compared with FM-EDFA. Yet much less work has been done in this area. To implement FM-DRAs in SDM systems, their performance should be carefully optimized. In this paper, modal gain and saturation characteristics of intermodal Raman amplification in FMFs have been fully investigated by tailoring the refractive-index profiles and doping levels of different FMF designs. For 50-km-long FMF with -3 dBm signal at 1550 nm and a 20-25 dBm pump at 1455 nm, the optimized modal-equalization of Raman gain and NF are provided depending on various fiber cross-section and pumping configuration with respect to modes/wavelengths. The pumpsignal modal-overlap integrals for each of the four mode-groups with normalized frequency V=5 have been exploited, resulting in a mean gain of 10 dB within 1 dB of equalization for 16 gain coefficients. Our results show it should be possible to design FMF with larger intermodal nonlinearity and better dispersion characteristics to achieve desirable Raman gain.
The Asymmetric Leximin Solution
Driesen, Bram W.
2012-01-01
In this article we define and characterize a class of asymmetric leximin solutions, that contains both the symmetric leximin solution of Imai[5] and the two-person asymmetric Kalai-Smorodinsky solution of Dubra [3] as special cases. Solutions in this class combine three attractive features: they are defined on the entire domain of convex n-person bargaining problems, they generally yield Pareto efficient solution outcomes, and asymmetries among bargainers are captured by a single parameter ve...
Graesser, Michael L.; Shoemaker, Ian M.; Vecchi, Luca
2011-01-01
In existing dark matter models with global symmetries the relic abundance of dark matter is either equal to that of anti-dark matter (thermal WIMP), or vastly larger, with essentially no remaining anti-dark matter (asymmetric dark matter). By exploring the consequences of a primordial asymmetry on the coupled dark matter and anti-dark matter Boltzmann equations we find large regions of parameter space that interpolate between these two extremes. Interestingly, this new asymmetric WIMP framewo...
Asymmetric deformation of contracting human gastrocnemius muscle
Kinugasa, Ryuta; Hodgson, John A.; Edgerton, V. Reggie; Sinha, Shantanu
2011-01-01
Muscle fiber deformation is related to its cellular structure, as well as its architectural arrangement within the musculoskeletal system. While playing an important role in aponeurosis displacement, and efficiency of force transmission to the tendon, such deformation also provides important clues about the underlying mechanical structure of the muscle. We hypothesized that muscle fiber cross section would deform asymmetrically to satisfy the observed constant volume of muscle during a contra...
Asymmetry in price transmission in agricultural markets
2013-01-01
This paper explores the asymmetries in price transmission from international to local markets. We expect the presence of large intermediaries in agricultural markets to lead to a stronger price transmission when international prices decline than when they rise. The empirical evidence confirms the presence of asymmetric price transmission consistent with the presence of large intermediaries with monopsony power.
Electroencephalograpic coherence
Simon Brežan
2004-08-01
Full Text Available Different brain areas process various aspects of information in parallel as well as segregated way. It is not known, how is this information integrated into a unitary percept or action. The binding problem is one of the key problems in understanding brain function. Synchronized oscillatory activity of neurons is one possible mechanism of the functional integration of different communicating brain areas. The binding has been well-studied in the visual system, but it could also serve as a mechanism in visuomotor integration or functional coupling present with other brain processes and behavioural modes (perception, complex motor behaviour, selective attention, learning, working memory, etc.. Interregional synchronization of the electroencephalographic (EEG signal can be determined by EEG coherence analysis. In the article we present a research example of coherence changes in a visuomotor task. During this task, coherence between visual and motor brain areas increased. This might reflect functional coupling between those areas, but it could also be influenced by other cognitive processes (e.g. selective attention. Coherence analysis is suitable for studying integrative brain function. Because it measures only one of the possible mechanisms of integration, it offers promise especially when combined with other electrophysiological and functional imaging methods.
Coherence, Pseudo-Coherence, and Non-Coherence.
Enkvist, Nils Erik
Analysis of the factors that make a text coherent or non-coherent suggests that total coherence requires cohesion not only on the textual surface but on the semantic level as well. Syntactic evidence of non-coherence includes lack of formal agreement blocking a potential cross-reference, anaphoric and cataphoric references that do not follow their…
An ion trap having two end cap electrodes disposed asymmetrically about a center of a ring electrode is disclosed. The inner surface of the end cap electrodes are conformed to an asymmetric pair of equipotential lines of the harmonic formed by the application of voltages to the electrodes. The asymmetry of the end cap electrodes allows ejection of charged species through the closer of the two electrodes which in turn allows for simultaneously detecting anions and cations expelled from the ion trap through the use of two detectors charged with opposite polarity. 4 figs
Coherence and Sense of Coherence
Dau, Susanne
2014-01-01
that sense of coherence is both related to conditional matters as learning environments, structure, clarity and linkage but also preconditioned matters and prerequisites among participants related to experiences and convenience. It is stressed that this calls for continuous assessment and reflections...
Coherence and Sense of Coherence
Dau, Susanne
2014-01-01
that sense of coherence is both related to conditional matters as learning environments, structure, clarity and linkage but also preconditioned matters and prerequisites among participants related to experiences and convenience. It is stressed that this calls for continuous assessment and reflections...... upon these terms and conditions if the student shall be able acquire the necessary competencies....
Asymmetric reactions in continuous flow
Xiao Yin Mak
2009-04-01
Full Text Available An overview of asymmetric synthesis in continuous flow and microreactors is presented in this review. Applications of homogeneous and heterogeneous asymmetric catalysis as well as biocatalysis in flow are discussed.
Low-kilovolt coherent electron diffractive imaging instrument based on a single-atom electron source
Lin, Chun-Yueh [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Chang, Wei-Tse; Chen, Yi-Sheng; Hwu, En-Te; Chang, Chia-Seng; Hwang, Ing-Shouh, E-mail: ishwang@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Hsu, Wei-Hao [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China)
2016-03-15
In this work, a transmission-type, low-kilovolt coherent electron diffractive imaging instrument was constructed. It comprised a single-atom field emitter, a triple-element electrostatic lens, a sample holder, and a retractable delay line detector to record the diffraction patterns at different positions behind the sample. It was designed to image materials thinner than 3 nm. The authors analyzed the asymmetric triple-element electrostatic lens for focusing the electron beams and achieved a focused beam spot of 87 nm on the sample plane at the electron energy of 2 kV. High-angle coherent diffraction patterns of a suspended graphene sample corresponding to (0.62 Å){sup −1} were recorded. This work demonstrated the potential of coherent diffractive imaging of thin two-dimensional materials, biological molecules, and nano-objects at a voltage between 1 and 10 kV. The ultimate goal of this instrument is to achieve atomic resolution of these materials with high contrast and little radiation damage.
Low-kilovolt coherent electron diffractive imaging instrument based on a single-atom electron source
In this work, a transmission-type, low-kilovolt coherent electron diffractive imaging instrument was constructed. It comprised a single-atom field emitter, a triple-element electrostatic lens, a sample holder, and a retractable delay line detector to record the diffraction patterns at different positions behind the sample. It was designed to image materials thinner than 3 nm. The authors analyzed the asymmetric triple-element electrostatic lens for focusing the electron beams and achieved a focused beam spot of 87 nm on the sample plane at the electron energy of 2 kV. High-angle coherent diffraction patterns of a suspended graphene sample corresponding to (0.62 Å)−1 were recorded. This work demonstrated the potential of coherent diffractive imaging of thin two-dimensional materials, biological molecules, and nano-objects at a voltage between 1 and 10 kV. The ultimate goal of this instrument is to achieve atomic resolution of these materials with high contrast and little radiation damage
Origin of asymmetric reversal modes in ferromagnetic/antiferromagnetic multilayers
Beckmann, B.; Nowak, U.; Usadel, K. D.
2004-01-01
Experimentally an asymmetry of the reversal modes has been found in certain exchange bias systems. From a numerical investigation of the domain state model evidence is gained that this effect depends on the angle between the easy axis of the antiferromagnet and the applied magnetic field. Depending on this angle the ferromagnet reverses either symmetrically, e. g. by a coherent rotation on both sides of the loop, or the reversal is asymmetric with a non uniform reversal mode for the ascending...
Asymmetric information and economics
Frieden, B. Roy; Hawkins, Raymond J.
2010-01-01
We present an expression of the economic concept of asymmetric information with which it is possible to derive the dynamical laws of an economy. To illustrate the utility of this approach we show how the assumption of optimal information flow leads to a general class of investment strategies including the well-known Q theory of Tobin. Novel consequences of this formalism include a natural definition of market efficiency and an uncertainty principle relating capital stock and investment flow.
Asymmetric Organocatalytic Cycloadditions
Mose, Rasmus
2016-01-01
were pioneered by Otto Paul Hermann Diels and Kurt Alder who discovered what later became known as the Diels Alder reaction. The Diels Alder reaction is a [4+2] cycloaddition in which a π4 component reacts with a π2 component via a cyclic transition state to generate a 6 membered ring. This reaction...... reactions constitute the first organocatalytic asymmetric higher order cycloadditions and a rational for the periselectivity and stereoselectivity is provided based on experimental and computational investigations....
Asymmetric extractions in orthodontics
Camilo Aquino Melgaço
2012-04-01
Full Text Available INTRODUCTION: Extraction decisions are extremely important in during treatment planning. In addition to the extraction decision orthodontists have to choose what tooth should be extracted for the best solution of the problem and the esthetic/functional benefit of the patient. OBJECTIVE: This article aims at reviewing the literature relating the advantages, disadvantages and clinical implications of asymmetric extractions to orthodontics. METHODS: Keywords were selected in English and Portuguese and the EndNote 9 program was used for data base search in PubMed, Web of Science (WSc and LILACS. The selected articles were case reports, original articles and prospective or retrospective case-control studies concerning asymmetrical extractions of permanent teeth for the treatment of malocclusions. CONCLUSION: According to the literature reviewed asymmetric extractions can make some specific treatment mechanics easier. Cases finished with first permanent molars in Class II or III relationship in one or both sides seem not to cause esthetic or functional problems. However, diagnosis knowledge and mechanics control are essential for treatment success.
Asymmetric Evolutionary Games.
McAvoy, Alex; Hauert, Christoph
2015-08-01
Evolutionary game theory is a powerful framework for studying evolution in populations of interacting individuals. A common assumption in evolutionary game theory is that interactions are symmetric, which means that the players are distinguished by only their strategies. In nature, however, the microscopic interactions between players are nearly always asymmetric due to environmental effects, differing baseline characteristics, and other possible sources of heterogeneity. To model these phenomena, we introduce into evolutionary game theory two broad classes of asymmetric interactions: ecological and genotypic. Ecological asymmetry results from variation in the environments of the players, while genotypic asymmetry is a consequence of the players having differing baseline genotypes. We develop a theory of these forms of asymmetry for games in structured populations and use the classical social dilemmas, the Prisoner's Dilemma and the Snowdrift Game, for illustrations. Interestingly, asymmetric games reveal essential differences between models of genetic evolution based on reproduction and models of cultural evolution based on imitation that are not apparent in symmetric games. PMID:26308326
何明烈; 戢焕奇
2008-01-01
Based on the investigation of the origin and definition of topic as well as the classification of textual coherence, this paper ana-lyzes the function of topic to non-coherence, imphcit coherence and explicit coherence, and concludes that topic relevance is the primary cri-terion for textual coherence.
IS PRICE TRANSMISSION SYMMETRIC OVER TRANSNATIONALVALUE CHAINS FOR CODFISH PRODUCTS ?
Menezes, Rui; Dionísio, Andreia
2008-01-01
This paper uses a threshold adjustment methodology to find out whether price transmission over the cod value chain between Norway and Portugal is asymmetric. The basic setting relies on price theory and the relationship between prices in the fish market. Empirical tests of price transmission use a cointegration framework similar to many other non-stationary time series analyses. However, it appears that testing for asymmetric price transmission has not been done so often in the...
Cheng, Jun; Tiyaboonchai, Amita; Yamashita, Yukiko M.; Hunt, Alan J.
2011-01-01
Many stem cells divide asymmetrically to balance self-renewal and differentiation. In Drosophila testes, two stem cell populations, germline stem cells (GSCs) and somatic cyst stem cells (CySCs), cohere and regulate one another. Here, we report that CySCs divide asymmetrically through repositioning the mitotic spindle around anaphase. CySC spindle repositioning requires functional centrosomes, Dynein and the actin-membrane linker Moesin. Anaphase spindle repositioning is required to achieve h...
Coherence in electron transfer pathways.
Skourtis, Spiros S; Beratan, David N; Waldeck, David H
2011-01-01
Central to the view of electron-transfer reactions is the idea that nuclear motion generates a transition state geometry at which the electron/hole amplitude propagates coherently from the electron donor to the electron acceptor. In the weakly coupled or nonadiabatic regime, the electron amplitude tunnels through an electronic barrier between the donor and acceptor. The structure of the barrier is determined by the covalent and noncovalent interactions of the bridge. Because the tunneling barrier depends on the nuclear coordinates of the reactants (and on the surrounding medium), the tunneling barrier is highly anisotropic, and it is useful to identify particular routes, or pathways, along which the transmission amplitude propagates. Moreover, when more than one such pathway exists, and the paths give rise to comparable transmission amplitude magnitudes, one may expect to observe quantum interferences among pathways if the propagation remains coherent. Given that the effective tunneling barrier height and width are affected by the nuclear positions, the modulation of the nuclear coordinates will lead to a modulation of the tunneling barrier and hence of the electron flow. For long distance electron transfer in biological and biomimetic systems, nuclear fluctuations, arising from flexible protein moieties and mobile water bridges, can become quite significant. We discuss experimental and theoretical results that explore the quantum interferences among coupling pathways in electron-transfer kinetics; we emphasize recent data and theories associated with the signatures of chirality and inelastic processes, which are manifested in the tunneling pathway coherence (or absence of coherence). PMID:23833692
Revealing Hidden Coherence in Partially Coherent Light
Svozilík, Jiří; Peřina, Jan; Torres, Juan P
2015-01-01
The coherence of a system can be ultimately related to the nature of its correlations with the surroundings (outside world). The system can be, for instance, the polarization of a photon, which forms part of a polarization-entangled two-photon state, or the spatial shape of a coherent beam, where each spatial mode bears different polarizations. Whereas a local unitary transformation of the system do not affect its coherence, global unitary transformations modifying both the system and its surroundings can enhance its coherence transforming mutual correlations into coherence. The question naturally arises of what is the best measure that quantifies the correlations that can be turned into coherence, and how much coherence can be extracted. We answer both questions, and illustrate its application for some typical simple systems, with the aim at illuminating the general concept of enhancing coherence by modifying correlations.
Phase coherence induced by correlated disorder
Hong, Hyunsuk; O'Keeffe, Kevin P.; Strogatz, Steven H.
2016-02-01
We consider a mean-field model of coupled phase oscillators with quenched disorder in the coupling strengths and natural frequencies. When these two kinds of disorder are uncorrelated (and when the positive and negative couplings are equal in number and strength), it is known that phase coherence cannot occur and synchronization is absent. Here we explore the effects of correlating the disorder. Specifically, we assume that any given oscillator either attracts or repels all the others, and that the sign of the interaction is deterministically correlated with the given oscillator's natural frequency. For symmetrically correlated disorder with zero mean, we find that the system spontaneously synchronizes, once the width of the frequency distribution falls below a critical value. For asymmetrically correlated disorder, the model displays coherent traveling waves: the complex order parameter becomes nonzero and rotates with constant frequency different from the system's mean natural frequency. Thus, in both cases, correlated disorder can trigger phase coherence.
Facilitated Asymmetric Exclusion
Gabel, Alan; Krapivsky, P. L.; Redner, S.
2010-01-01
We introduce a class of facilitated asymmetric exclusion processes in which particles are pushed by neighbors from behind. For the simplest version in which a particle can hop to its vacant right neighbor only if its left neighbor is occupied, we determine the steady state current and the distribution of cluster sizes on a ring. We show that an initial density downstep develops into a rarefaction wave that can have a jump discontinuity at the leading edge, while an upstep results in a shock w...
Tunable asymmetric mode conversion using the dark-mode of three-mode waveguide system.
Kim, Joonsoo; Lee, Seung-Yeol; Lee, Yohan; Kim, Hwi; Lee, Byoungho
2014-11-17
A design scheme for low-reflection asymmetric mode conversion structure in three-mode waveguide system is proposed. By using a dark-mode of three-mode system, which can be interpreted in terms of destructive interference of transition amplitudes, the transmission characteristics for forward and backward directions can be designed separately. After explanation of the proposed design scheme, we demonstrate an example of asymmetric mode converter that consists of two gratings. The proposed scheme may be useful for the design of tunable asymmetric transmission devices due to its design flexibility and efficient design process. PMID:25402109
Asymmetric first order shear horizontal guided waves propagation in a tapered plate
In this paper, through numerical simulation of the first order shear horizontal guided waves propagation in a homogeneous tapered plate, we have realized sound unidirectional transmission based on the mode conversion mechanism. We also find that the contrast transmission ratio of unidirectional transmission is highly influenced by the slope angle of tapered edge. And the working frequency range of the asymmetric transmission can be easily controlled by the height of tapered surface or the thickness of slab. This asymmetric system shows potentially significant applications in various sound devices. - Highlights: • We study the sound unidirectional transmission for SH1 guided wave in a homogeneous tapered plate. • The contrast transmission ratio of unidirectional transmission is highly influenced by the slope angle. • The working frequency range of unidirectional transmission can be easily controlled by structure parameters
陆虹
2012-01-01
This paper employs STR model and LM statistic test to make an empirical study of the asymmetric effect of credit transmission channel of monetary policy and its regional economic effects based on relevant quarter data from 1996 to 2012. The results show that the effect of credit transmis sion channel of monetary policy in China is obviously featured by asymme try, namely strong nonlinearity, and this asymmetry has different effects on economic operation in the whole nation and eastern, central and western re gions.%文章以1996-2012年的相关季度统计数据,运用STR模型和LM统计检验方法,对我国货币政策信贷传导渠道的非对称效应及地区经济影响进行了实证研究。结果显示,我国货币政策信贷传导渠道效果存在明显的不对称特性,即具有很强的非线性特征;同时,这种不对称性对我国及东中西部地区的经济运行存在不同的影响。
Asher, D. J.; Clube, S. V. M.; Napier, W. M.; Steel, D. I.
We review the theoretical and observational evidence that, on timescales relevant to mankind, the prime collision hazard is posed by temporally correlated impacts (coherent catastrophism, Δt ˜ 10 2-10 4 yr) rather than random ones (stochastic catastrophism, Δt ˜ 10 5-10 8 yr). The mechanism whereby coherent incursions into and through the terrestrial atmosphere occur is described as being the result of giant cometary bodies arriving in orbits with perihelia in the inner solar system. Hierarchical fragmentation of such large (100 km-plus) bodies — due to thermal stresses near perihelion, collisions in the asteroid belt, or passages through the Jovian Roche radius — results in numerous ˜kilometre-sized objects being left in short-period orbits, and appearing in telescopic searches as Apollo-type asteroids. Many more smaller objects, in the 10-100 metre size range and only recently observed, by the Spacewatch team, are expected to be in replenished clusters in particular orbits as a result of continuing disintegrations of large, differentiated, cometary objects. Gravitational perturbations by Jupiter bring these clusters around to have a node at 1 AU in a cyclic fashion, leading to impacts at certain times of year every few years during active periods lasting a few centuries, such periods being separated by intervals of a few millennia. Furthermore, fragmentations within the hierarchy result in significant bombardment commensurabilities ( Δt ˜ 10-10 2 yr) during active periods occurring at random intervals ( Δt ˜ 10 2-10 3 yr). It appears that the Earth has been subject to such impacts since the break-up of such a comet ˜2×10 4 years ago; currently we are not passing through a high-risk epoch, although some phenomena originating in the products of this break-up have been observed in the 20th century. This most recent hierarchical disintegration, associated with four well-known meteor showers and termed the Taurid Complex, is now recognized as resulting
Asymmetric quantum cloning machines
A family of asymmetric cloning machines for quantum bits and N-dimensional quantum states is introduced. These machines produce two approximate copies of a single quantum state that emerge from two distinct channels. In particular, an asymmetric Pauli cloning machine is defined that makes two imperfect copies of a quantum bit, while the overall input-to-output operation for each copy is a Pauli channel. A no-cloning inequality is derived, characterizing the impossibility of copying imposed by quantum mechanics. If p and p' are the probabilities of the depolarizing channels associated with the two outputs, the domain in (√p,√p')-space located inside a particular ellipse representing close-to-perfect cloning is forbidden. This ellipse tends to a circle when copying an N-dimensional state with N→∞, which has a simple semi-classical interpretation. The symmetric Pauli cloning machines are then used to provide an upper bound on the quantum capacity of the Pauli channel of probabilities px, py and pz. The capacity is proven to be vanishing if (√px, √py, √pz) lies outside an ellipsoid whose pole coincides with the depolarizing channel that underlies the universal cloning machine. Finally, the tradeoff between the quality of the two copies is shown to result from a complementarity akin to Heisenberg uncertainty principle. (author)
Reuveni, Shlomi; Eliazar, Iddo; Yechiali, Uri
2011-10-01
We introduce and explore the asymmetric inclusion process (ASIP), an exactly solvable bosonic counterpart of the fermionic asymmetric exclusion process (ASEP). In both processes, random events cause particles to propagate unidirectionally along a one-dimensional lattice of n sites. In the ASEP, particles are subject to exclusion interactions, whereas in the ASIP, particles are subject to inclusion interactions that coalesce them into inseparable clusters. We study the dynamics of the ASIP, derive evolution equations for the mean and probability generating function (PGF) of the sites’ occupancy vector, obtain explicit results for the above mean at steady state, and describe an iterative scheme for the computation of the PGF at steady state. We further obtain explicit results for the load distribution in steady state, with the load being the total number of particles present in all lattice sites. Finally, we address the problem of load optimization, and solve it under various criteria. The ASIP model establishes bridges between statistical physics and queueing theory as it represents a tandem array of queueing systems with (unlimited) batch service, and a tandem array of growth-collapse processes.
Alternative Asymmetric Stochastic Volatility Models
M. Asai (Manabu); M.J. McAleer (Michael)
2010-01-01
textabstractThe stochastic volatility model usually incorporates asymmetric effects by introducing the negative correlation between the innovations in returns and volatility. In this paper, we propose a new asymmetric stochastic volatility model, based on the leverage and size effects. The model is
Engineered Asymmetric Synthetic Vesicles
Lu, Li; Chiarot, Paul
2013-11-01
Synthetic vesicles are small, fluid-filled spheres that are enclosed by a bilayer of lipid molecules. They can be used as models for investigating membrane biology and as delivery vehicles for pharmaceuticals. In practice, it is difficult to simultaneously control membrane asymmetry, unilamellarity, vesicle size, vesicle-to-vesicle uniformity, and luminal content. Membrane asymmetry, where each leaflet of the bilayer is composed of different lipids, is of particular importance as it is a feature of most natural membranes. In this study, we leverage microfluidic technology to build asymmetric vesicles at high-throughput. We use the precise flow control offered by microfluidic devices to make highly uniform emulsions, with controlled internal content, that serve as templates to build the synthetic vesicles. Flow focusing, dielectrophoretic steering, and interfacial lipid self-assembly are critical procedures performed on-chip to produce the vesicles. Fluorescent and confocal microscopy are used to evaluate the vesicle characteristics.
I. Cabrera-Munguia
2015-04-01
Full Text Available A 6-parametric asymptotically flat exact solution, describing a two-body system of asymmetric black dyons, is studied. The system consists of two unequal counterrotating Kerr–Newman black holes, endowed with electric and magnetic charges which are equal but opposite in sign, separated by a massless strut. The Smarr formula is generalized in order to take into account their contribution to the mass. The expressions for the horizon half-length parameters σ1 and σ2, as functions of the Komar parameters and of the coordinate distance, are displayed, and the thermodynamic properties of the two-body system are studied. Furthermore, the seven physical parameters satisfy a simple algebraic relation which can be understood as a dynamical scenario, in which the physical properties of one body are affected by the ones of the other body.
We study a natural implementation of Asymmetric Dark Matter in Twin Higgs models. The mirroring of the Standard Model strong sector suggests that a twin baryon with mass around 5 GeV is a natural Dark Matter candidate once a twin baryon number asymmetry comparable to the SM asymmetry is generated. We explore twin baryon Dark Matter in two different scenarios, one with minimal content in the twin sector and one with a complete copy of the SM, including a light twin photon. The essential requirements for successful thermal history are presented, and in doing so we address some of the cosmological issues common to many Twin Higgs models. The required interactions we introduce predict signatures at direct detection experiments and at the LHC
Organizing for Asymmetric Collaboration
Nielsen, Jørn Flohr; Sørensen, Henrik B.
meet each other. On the contrary, we assume that asymmetry is both important and normal; moreover, asymmetry should be considered to be more complex than economists indicate with their concept of asymmetric information. Thus, the aim of the paper is to explore how asymmetries related to partners...... The vision of new organizational forms consists of less-organized networks and alliances between organizations, in which collaborative capabilities are assumed to be crucial (Miles et al., 2005). The path to such new forms may go through fragile cooperative efforts. Despite the good will of many......' different motives and different situational factors appear in an interorganizational setting. We classify interfaces according to the symmetry/asymmetry in the respective parent organizations' resources, commitment, and control of representatives and indicate how classification schemes can be used to...
Annihilating Asymmetric Dark Matter
Bell, Nicole F; Shoemaker, Ian M
2014-01-01
The relic abundance of particle and antiparticle dark matter (DM) need not be vastly different in thermal asymmetric dark matter (ADM) models. By considering the effect of a primordial asymmetry on the thermal Boltzmann evolution of coupled DM and anti-DM, we derive the requisite annihilation cross section. This is used in conjunction with CMB and Fermi-LAT gamma-ray data to impose a limit on the number density of anti-DM particles surviving thermal freeze-out. When the extended gamma-ray emission from the Galactic Center is reanalyzed in a thermal ADM framework, we find that annihilation into $\\tau$ leptons prefer anti-DM number densities 1-4$\\%$ that of DM while the $b$-quark channel prefers 50-100$\\%$.
Cooperative Emission of a Coherent Superflash of Light
Kwong, CC; Yang, T; Pramod, MS; Pandey, K.; Delande, D; Pierrat, R; Wilkowski, D.
2014-01-01
We investigate the transient coherent transmission of light through an optically thick cold stron-tium gas. We observe a coherent superflash just after an abrupt probe extinction, with peak intensity more than three times the incident one. We show that this coherent superflash is a direct signature of the cooperative forward emission of the atoms. By engineering fast transient phenomena on the incident field, we give a clear and simple picture of the physical mechanisms at play.
Continuous variable quantum cryptography using coherent states
Grosshans, Frédéric; Grangier, Philippe
2002-01-01
5 pages, 1 figure. In v2 minor rewriting for clarity, references added International audience We propose several methods for quantum key distribution (QKD) based upon the generation and transmission of random distributions of coherent or squeezed states, and we show that they are are secure against individual eavesdropping attacks. These protocols require that the transmission of the optical line between Alice and Bob is larger than 50 %, but they do not rely on "non-classical" features...
Metal rolling - Asymmetrical rolling process
Alexa, V.; Raţiu, S.; Kiss, I.
2016-02-01
The development of theory and practice related to the asymmetric longitudinal rolling process is based on the general theory of metalworking by pressure and symmetric rolling theory, to which a large number of scientists brought their contribution. The rolling of metal materials was a serious problem throughout history, either economically or technically, because the plating technologies enabled the consumption of raw materials (scarce and expensive) to be reduced, while improving the mechanical properties. Knowing the force parameters related to asymmetric rolling leads to the optimization of energy and raw material consumption. This paper presents data on symmetric rolling process, in order to comparatively highlight the particularities of the asymmetric process.
Gould, Victoria; Hartmann, Miklos; Ruskuc, Nik
2014-01-01
A monoid $S$ is said to be right coherent if every finitely generated subact of every finitely presented right $S$-act is finitely presented. Left coherency is defined dually and $S$ is coherent if it is both right and left coherent. These notions are analogous to those for a ring $R$ (where, of course, $S$-acts are replaced by $R$-modules). Choo, Lam and Luft have shown that free rings are coherent. In this note we prove that, correspondingly, any free monoid is coherent, thus answering a qu...
Asymmetric Gepner Models (Revisited)
Gato-Rivera, B
2010-01-01
We reconsider a class of heterotic string theories studied in 1989, based on tensor products of N=2 minimal models with asymmetric simple current invariants. We extend this analysis from (2,2) and (1,2) spectra to (0,2) spectra with SO(10) broken to the Standard Model. In the latter case the spectrum must contain fractionally charged particles. We find that in nearly all cases at least some of them are massless. However, we identify a large subclass where the fractional charges are at worst half-integer, and often vector-like. The number of families is very often reduced in comparison to the 1989 results, but there are no new tensor combinations yielding three families. All tensor combinations turn out to fall into two classes: those where the number of families is always divisible by three, and those where it is never divisible by three. We find an empirical rule to determine the class, which appears to extend beyond minimal N=2 tensor products. We observe that distributions of physical quantities such as th...
Laser diode array and transmission optics
Kwon, Jin H.
1989-01-01
Information on laser diode array and transmission optics is given in viewgraph form. Information is given on coherent combining of laser diode arrays, amplification through a laser diode array, the far field pattern of a laser diode transmitter, and beam diameter at receiver vs. transmission distance.
Magnetically Modified Asymmetric Supercapacitors Project
National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project is for the development of an asymmetric supercapacitor that will have improved energy density and cycle...
Asymmetric transmission in planar chiral metamaterials: microscopic explanation
Novitsky, Andrey; Zhukovsky, S. V.
2011-01-01
Lorentz electron theory is a powerful approach for description of macroscopic parameters of a medium based on microscopic characteristics of the individual electron. For a planar array of chiral metallic split rings, we determine the averaged electron’s characteristics in a sprit ring and apply...
Partially coherent imaging and spatial coherence wavelets
A description of spatially partially coherent imaging based on the propagation of second order spatial coherence wavelets and marginal power spectra (Wigner distribution functions) is presented. In this dynamics, the spatial coherence wavelets will be affected by the system through its elementary transfer function. The consistency of the model with the both extreme cases of full coherent and incoherent imaging was proved. In the last case we obtained the classical concept of optical transfer function as a simple integral of the elementary transfer function. Furthermore, the elementary incoherent response function was introduced as the Fourier transform of the elementary transfer function. It describes the propagation of spatial coherence wavelets form each object point to each image point through a specific point on the pupil planes. The point spread function of the system was obtained by a simple integral of the elementary incoherent response function. (author)
Active Matter on Asymmetric Substrates
Reichhardt, C. J. Olson; Drocco, J.; Mai, T.; Wan, M. B.; Reichhardt, C.
2011-01-01
For collections of particles in a thermal bath interacting with an asymmetric substrate, it is possible for a ratchet effect to occur where the particles undergo a net dc motion in response to an ac forcing. Ratchet effects have been demonstrated in a variety of systems including colloids as well as magnetic vortices in type-II superconductors. Here we examine the case of active matter or self-driven particles interacting with asymmetric substrates. Active matter systems include self-motile c...
Mobile Termination with Asymmetric Networks
Dewenter, Ralf; Haucap, Justus
2003-01-01
This paper examines mobile termination fees and their regulation when networks are asymmetric in size. It is demonstrated that with consumer ignorance about the exact termination rates (a) a mobile network?s termination rate is the higher the smaller the network?s size (as measured through its subscriber base) and (b) asymmetric regulation of only the larger operators in a market will, ce-teris paribus, induce the smaller operators to increase their termination rates. The results are supporte...
Multicatalyst system in asymmetric catalysis
Zhou, Jian
2014-01-01
This book introduces multi-catalyst systems by describing their mechanism and advantages in asymmetric catalysis. Helps organic chemists perform more efficient catalysis with step-by-step methods Overviews new concepts and progress for greener and economic catalytic reactions Covers topics of interest in asymmetric catalysis including bifunctional catalysis, cooperative catalysis, multimetallic catalysis, and novel tandem reactions Has applications for pharmaceuticals, agrochemicals, materials, and flavour and fragrance
Asymmetric Dark Matter from Leptogenesis
Falkowski, Adam; Ruderman, Joshua T.; Volansky, Tomer
2011-01-01
We present a new realization of asymmetric dark matter in which the dark matter and lepton asymmetries are generated simultaneously through two-sector leptogenesis. The right-handed neutrinos couple both to the Standard Model and to a hidden sector where the dark matter resides. This framework explains the lepton asymmetry, dark matter abundance and neutrino masses all at once. In contrast to previous realizations of asymmetric dark matter, the model allows for a wide range of dark matter mas...
Secure Communication using Symmetric and Asymmetric Cryptographic Techniques
Asif Irshad Khan
2012-04-01
Full Text Available Satellite based communication is a way to transmit digital information from one geographic location to another by utilizing satellites. Satellite as communication medium to transfer data vulnerable various types of information security threat, and require a novel methodology for safe and secure data transmission over satellite. In this paper a methodology is proposed to ensure safe and secured transferred of data or information for satellite based communication using symmetric and asymmetric Cryptographic techniques
ASYMMETRIC PRICE RELATIONSHIPS IN THE U.S. BROILER INDUSTRY
Bernard, John C.; Willett, Lois Schertz
1996-01-01
This study presents a testing methodology to analyze potential price asymmetries among the farm, wholesale, and retail levels of the U.S. broiler industry. Lag length, direction of causality and power of the integrators in the industry have allowed the wholesale price to become the center, causal price in the market. Asymmetric price transmissions, however, are limited. While downward movements in the wholesale price are passed on more fully to growers than increases in the wholesale price, o...
Asymmetric Gepner models (revisited)
Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands)] [Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands)] [Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain)] [IMAPP, Radboud Universiteit, Nijmegen (Netherlands)
2010-12-11
We reconsider a class of heterotic string theories studied in 1989, based on tensor products of N=2 minimal models with asymmetric simple current invariants. We extend this analysis from (2,2) and (1,2) spectra to (0,2) spectra with SO(10) broken to the Standard Model. In the latter case the spectrum must contain fractionally charged particles. We find that in nearly all cases at least some of them are massless. However, we identify a large subclass where the fractional charges are at worst half-integer, and often vector-like. The number of families is very often reduced in comparison to the 1989 results, but there are no new tensor combinations yielding three families. All tensor combinations turn out to fall into two classes: those where the number of families is always divisible by three, and those where it is never divisible by three. We find an empirical rule to determine the class, which appears to extend beyond minimal N=2 tensor products. We observe that distributions of physical quantities such as the number of families, singlets and mirrors have an interesting tendency towards smaller values as the gauge groups approaches the Standard Model. We compare our results with an analogous class of free fermionic models. This displays similar features, but with less resolution. Finally we present a complete scan of the three family models based on the triply-exceptional combination (1,16{sup *},16{sup *},16{sup *}) identified originally by Gepner. We find 1220 distinct three family spectra in this case, forming 610 mirror pairs. About half of them have the gauge group SU(3)xSU(2){sub L}xSU(2){sub R}xU(1){sup 5}, the theoretical minimum, and many others are trinification models.
On Longitudinal Spectral Coherence
Kristensen, Leif
1979-01-01
It is demonstrated that the longitudinal spectral coherence differs significantly from the transversal spectral coherence in its dependence on displacement and frequency. An expression for the longitudinal coherence is derived and it is shown how the scale of turbulence, the displacement between ...
Denise Pumain
2001-01-01
Full Text Available The present situation provides a challenge for us to reconsider the necessary link between science and pedagogy, between research and the transmission of knowledge. The Ministry of National education has just inaugurated a broad consultation of teachers on every level with a view to modernising and giving coherence to the programs of secondary education. Armand Frémont will head the group of experts responsible for history and geography. Is this a coincidence? The changeover in the jury for t...
Experiment with asymmetric target crystals in LEBRA-PXR
In order to investigate the geometrical effect of a target crystal shape on parametric X-ray radiation (PXR), target crystals with a knife-edge-shaped cut surface were prepared and the experiments using such crystals have been carried out using the LEBRA-PXR system at Nihon University. The results shows that reducing the number of the emission surface of PXR improves the spatial coherence of PXR beam. In addition, the use of asymmetric cut surface for the target produces relatively intense PXR emission. Although the degradation of the spatial coherence of the PXR beam, this target condition makes it possible to obtain practical radiograph image with the measurement time less than 1 minute. (author)
Short coherent control pulse with small random errors in its direction
Zhi-Kun, Su; Shao-Ji, Jiang
2012-01-01
The finite-amplitude short coherent control pulse with small random errors in its direction is considered. We derive the conditions for it to approximate an ideal delta-shaped pulse up to an error in the second order of pulse duration. Whether the symmetric and asymmetric pulse shapes would fulfill these conditions is also analyzed. The result shows that, under one of these conditions, all symmetric pulse shapes can fulfill this condition but not for all asymmetric ones..
Hydroxamic acids in asymmetric synthesis.
Li, Zhi; Yamamoto, Hisashi
2013-02-19
Metal-catalyzed stereoselective reactions are a central theme in organic chemistry research. In these reactions, the stereoselection is achieved predominantly by introducing chiral ligands at the metal catalyst's center. For decades, researchers have sought better chiral ligands for asymmetric catalysis and have made great progress. Nevertheless, to achieve optimal stereoselectivity and to catalyze new reactions, new chiral ligands are needed. Because of their high metal affinity, hydroxamic acids play major roles across a broad spectrum of fields from biochemistry to metal extraction. Dr. K. Barry Sharpless first revealed their potential as chiral ligands for asymmetric synthesis in 1977: He published the chiral vanadium-hydroxamic-acid-catalyzed, enantioselective epoxidation of allylic alcohols before his discovery of Sharpless asymmetric epoxidation, which uses the titanium-tartrate complex as the chiral reagent. However, researchers have reported few highly enantioselective reactions using metal-hydroxamic acid as catalysts since then. This Account summarizes our research on metal-catalyzed asymmetric epoxidation using hydroxamic acids as chiral ligands. We designed and synthesized a series of new hydroxamic acids, most notably the C2-symmetric bis-hydroxamic acid (BHA) family. V-BHA-catalyzed epoxidation of allylic and homoallylic alcohols achieved higher activity and stereoselectivity than Sharpless asymmetric epoxidation in many cases. Changing the metal species led to a series of unprecedented asymmetric epoxidation reactions, such as (i) single olefins and sulfides with Mo-BHA, (ii) homoallylic and bishomoallylic alcohols with Zr- and Hf-BHA, and (iii) N-alkenyl sulfonamides and N-sulfonyl imines with Hf-BHA. These reactions produce uniquely functionalized chiral epoxides with good yields and enantioselectivities. PMID:23157425
Asymmetric Flexible Supercapacitor Stack
Leela Mohana Reddy A
2008-01-01
Full Text Available AbstractElectrical double layer supercapacitor is very significant in the field of electrical energy storage which can be the solution for the current revolution in the electronic devices like mobile phones, camera flashes which needs flexible and miniaturized energy storage device with all non-aqueous components. The multiwalled carbon nanotubes (MWNTs have been synthesized by catalytic chemical vapor deposition technique over hydrogen decrepitated Mischmetal (Mm based AB3alloy hydride. The polymer dispersed MWNTs have been obtained by insitu polymerization and the metal oxide/MWNTs were synthesized by sol-gel method. Morphological characterizations of polymer dispersed MWNTs have been carried out using scanning electron microscopy (SEM, transmission electron microscopy (TEM and HRTEM. An assymetric double supercapacitor stack has been fabricated using polymer/MWNTs and metal oxide/MWNTs coated over flexible carbon fabric as electrodes and nafion®membrane as a solid electrolyte. Electrochemical performance of the supercapacitor stack has been investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy.
Asymmetric counterpropagating fronts without flow.
Andrade-Silva, I; Clerc, M G; Odent, V
2015-06-01
Out-of-equilibrium systems exhibit domain walls between different states. These walls, depending on the type of connected states, can display rich spatiotemporal dynamics. In this Rapid Communication, we investigate the asymmetrical counterpropagation of fronts in an in-plane-switching cell filled with a nematic liquid crystal. Experimentally, we characterize the different front shapes and propagation speeds. These fronts present dissimilar elastic deformations that are responsible for their asymmetric speeds. Theoretically, using a phenomenological model, we describe the observed dynamics with fair agreement. PMID:26172647
Incompressibility of asymmetric nuclear matter
Chen, Lie-Wen; Cai, Bao-Jun; Shen, Chun; Ko, Che Ming; Xu, Jun; Li, Bao-An(Department of Physics and Astronomy, Texas A&M University-Commerce, Commerce, TX, 75429-3011, USA)
2009-01-01
The incompressibility $K_sat(\\delta)$ of isospin asymmetric nuclear matter at its saturation density. Our results show that in the expansion of $K_sat(\\delta)$ in powers of isospin asymmetry $\\delta$, i.e., $K_sat(\\delta )$=K_{0}+K_{sat,2}\\delta^{2}+K_{sat,4}\\delta^{4}+O(\\delta^{6})$, the magnitude of the 4th-order K_{sat,4} parameter is generally small. The 2nd-order K_{sat,2} parameter thus essentially characterizes the isospin dependence of the incompressibility of asymmetric nuclear matte...
Asymmetric interference in molecular photoprocesses
For the first time, the Coulomb continuum effects in asymmetric molecular interference have been studied analytically in photoionization, photorecombination, bremsstrahlung and Compton ionization. Simple, closed-form factors describe the interference not only in monochromatic photoprocesses, but also in the continuous photoelectron spectra generated by attosecond x-ray pulses with a frequency-dependent phase and broad bandwidth. Using HeH2+ molecular ion as an example, we show how the plane wave interference pattern is strongly modified by the two-centre Coulomb continuum. Asymmetric Coulomb continuum introduces qualitative changes in a photoionization process
Buss, Ginters
2011-01-01
The paper proposes an extension of the symmetric Baxter-King band pass filter to an asymmetric Baxter-King filter. The optimal correction scheme of the ideal filter weights is the same as in the symmetric version, i.e, cut the ideal filter at the appropriate length and add a constant to all filter weights to ensure zero weight on zero frequency. Since the symmetric Baxter-King filter is unable to extract the desired signal at the very ends of the series, the extension to an asymmetric filter...
Forces between asymmetric polymer brushes
Shim, D.F.K.; Cates, M. E.
1990-01-01
We study the equilibrium compression of asymmetric polymer brushes grafted on flat plates, under athermal and theta solvent conditions, using a lattice self-consistent field (SCF) approach. We find that the separation d between two plates coated asymmetrically with brushes of type 1 and 2, as a function of the force F, obeys the "bisection rule", d(F) = (d1(F) + d 2(F)) /2 where d1(F)and d 2(F) are the corresponding separations for the symmetric brushes of type 1 and 2 respectively.The bisect...
Research on asymmetric "Jerusalem" unit
Jun Lu; Jianbo Wang
2009-01-01
An asymmetric Jerusalem unit and the frequency selective surface(FSS)structure composed of such units are designed.The transmittance of the designed FSS structure is calculated by mode-matching method and compared with the test results.The comparison results show that the FSS center frequency of the asymmetric structure unit drifts little with the variation of the incident angles of the electromagnetic waves and keeps relatively stable.The research offers a new choice for the application of FSS under the large scanning angle of electromagnetic waves.
This session on transmission issues focused on the role that transmission plays in electricity markets and the importance of getting the market structure right in terms of generation divestiture with buy back contracts, demand side responsive programs, transmission upgrades and long term contracts. The difficulties of distinguishing between market power and scarcity were examined along with some of the complications that ensue if transmission experiences congestion, as exemplified by the August 2003 blackout in eastern North America. The presentations described the best ways to handle transmission issues, and debated whether transmission should be deregulated or follow market forces. Issues of interconnections and reliability of connections were also debated along with the attempt to integrate renewables into the grid. Some presentations identified what new transmission must be built and what must be done to ensure that transmission gets built. The challenges and business opportunities for transmission in Alberta were discussed with reference to plans to invest in new infrastructure, where it is going outside of the province and how it works with other jurisdictions. Manitoba's Conawapa Hydro Project and its 2000 MW tie line to Ontario was also discussed. Some examples of non-optimal use of interconnections in Europe were also discussed in an effort to learn from these mistakes and avoid them in Canada. tabs., figs
Yukalov, V. I.; E. P. Yukalova
2004-01-01
The main part of this review is devoted to the comprehensive description of coherent radiation by nuclear spins. The theory of nuclear spin superradiance is developed and the experimental observations of this phenomenon are considered. The intriguing problem of how coherence develops from initially incoherent quantum fluctuations is analysed. All main types of coherent radiation by nuclear spins are discussed, which are: free nuclear induction, collective induction, maser generation, pure sup...
Tailoring the magnetic properties of Fe asymmetric nanodots
Asymmetric dots as a function of their geometry have been investigated using three-dimensional (3D) object oriented micromagnetic framework (OOMMF) code. The effect of shape asymmetry of the disk on coercivity and remanence is studied. Angular dependence of the remanence and coercivity is also addressed. Asymmetric dots are found to reverse their magnetization by nucleation and propagation of a vortex, when the field is applied parallel to the direction of asymmetry. However, complex reversal modes appear when the angle at which the external field is applied is varied, leading to a non-monotonic behavior of the coercivity and remanence. - Research highlights: → In this work, by means of numerical simulations we have investigated Fe asymmetrical dots as a function of their geometry. → Coercivity and remanence are strongly influenced by the asymmetry, presenting a non-monotonic behavior. → According to our results we can conclude that the existence of some degree of asymmetry defines the region of vortex nucleation and its chirality during the reversal of the magnetization. → Also we have extended our results to the case of an angular dependence of the coercivity and remanence, where a transition form vortex-mode to coherent-mode rotation has been observed. → The light shed by our results on these phenomena is not only of fundamental interest, but also of importance for the engineering of future high-density data storage systems for which asymmetry can be useful for tailoring specific magnetic characteristics of these systems.
Application Coherency Manager Project
National Aeronautics and Space Administration — This proposal describes an Application Coherency Manager that implements and manages the interdependencies of simulation, data, and platform information. It will...
Eesley, G L
1981-01-01
Coherent Raman Spectroscopy provides a unified and general account of the fundamental aspects of nonlinear Raman spectroscopy, also known as coherent Raman spectroscopy. The theoretical basis from which coherent Raman spectroscopy developed is described, along with its applications, utility, and implementation as well as advantages and disadvantages. Experimental data which typifies each technique is presented. This book is comprised of four chapters and opens with an overview of nonlinear optics and coherent Raman spectroscopy, followed by a discussion on nonlinear transfer function of matter
Electromagnetic spatial coherence wavelets
The recently introduced concept of spatial coherence wavelets is generalized for describing the propagation of electromagnetic fields in the free space. For this aim, the spatial coherence wavelet tensor is introduced as an elementary amount, in terms of which the formerly known quantities for this domain can be expressed. It allows analyzing the relationship between the spatial coherence properties and the polarization state of the electromagnetic wave. This approach is completely consistent with the recently introduced unified theory of coherence and polarization for random electromagnetic beams, but it provides a further insight about the causal relationship between the polarization states at different planes along the propagation path. (author)
On -Coherent Endomorphism Rings
Li-Xin Mao
2008-11-01
A ring is called right -coherent if every principal right ideal is finitely presented. Let $M_R$ be a right -module. We study the -coherence of the endomorphism ring of $M_R$. It is shown that is a right -coherent ring if and only if every endomorphism of $M_R$ has a pseudokernel in add $M_R; S$ is a left -coherent ring if and only if every endomorphism of $M_R$ has a pseudocokernel in add $M_R$. Some applications are given.
JET and COMPASS asymmetrical disruptions
Gerasimov, S.N.; Abreu, P.; Baruzzo, M.; Drozdov, V.; Dvornova, A.; Havlíček, Josef; Hender, T.C.; Hronová-Bilyková, Olena; Kruezi, U.; Li, X.; Markovič, Tomáš; Pánek, Radomír; Rubinacci, G.; Tsalas, M.; Ventre, S.; Villone, F.; Zakharov, L.E.
2015-01-01
Roč. 55, č. 11 (2015), s. 113006-113006. ISSN 0029-5515 R&D Projects: GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : tokamak * asymmetrical disruption * JET * COMPASS Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.062, year: 2014
Synthesis of Asymmetric Propanetriol Analogues
无
2002-01-01
From natural tartaric acid, (R)-2-benzyloxy-3-(2-tetrahydropyranyloxy) propanol 3 was designed and synthesized, and (R)-2-benzyloxy-3-(4-methoxybenzyloxy) propanol 7 was prepared in a new method. They can be used as chiral synthons of lysophosphatidic acid and other compounds with asymmetric propanetriol backbone.
Asymmetrical Switch Costs in Children
Ellefson, Michelle R.; Shapiron, Laura R.; Chater, Nick
2006-01-01
Switching between tasks produces decreases in performance as compared to repeating the same task. Asymmetrical switch costs occur when switching between two tasks of unequal difficulty. This asymmetry occurs because the cost is greater when switching to the less difficult task than when switching to the more difficult task. Various theories about…
Asymmetric Synthesis via Chiral Aziridines
Tanner, David Ackland; Harden, Adrian; Wyatt, Paul; Andersson, Pher G.; Johansson, Fredrik
1996-01-01
A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines)]. In the...
Ordering states with coherence measures
Liu, C. L.; Yu, Xiao-Dong; Xu, G. F.; Tong, D. M.
2016-07-01
The quantification of quantum coherence has attracted a growing attention, and based on various physical contexts, several coherence measures have been put forward. An interesting question is whether these coherence measures give the same ordering when they are used to quantify the coherence of quantum states. In this paper, we consider the two well-known coherence measures, the l_1 norm of coherence and the relative entropy of coherence, to show that there are the states for which the two measures give a different ordering. Our analysis can be extended to other coherence measures, and as an illustration of the extension we further consider the formation of coherence to show that the l_1 norm of coherence and the formation of coherence, as well as the relative entropy of coherence and the coherence of formation, do not give the same ordering too.
Fifth-Order Harmonic Generation using a Coherent Controlled Two-Pulsed Optical Field
刘婷婷; 王大威; 陆伟新; 孙泉; 杨宏; 蒋红兵; 龚旗煌
2002-01-01
We have experimentally studied the characteristics of fifth-order harmonic radiation produced by two coherent femtosecond laser pulses with a changeable relative phase. The intensities of harmonic generation are found to increase vith the coherent degree. In one optical period, the temporal variation of harmonics exhibits an asymmetric characteristic, vhich is interpreted in terms of ionization theory and the deformation of the wave packets of fundamental field contribution to harmonic generation.
Selfhealing of asymmetric Bessel-like modes
Israelsen, Stine Møller; Rishøj, Lars Søgaard; Rottwitt, Karsten
2014-01-01
We numerically investigate asymmetric Bessel-like modes in an aircladding fiber. The selfhealing ability of asymmetric Bessel-like modes is demonstrated and quantified including the angular dependency of this ability.......We numerically investigate asymmetric Bessel-like modes in an aircladding fiber. The selfhealing ability of asymmetric Bessel-like modes is demonstrated and quantified including the angular dependency of this ability....
Chirped photonic crystal with different symmetries for asymmetric light propagation
Singh, Brahm Raj; Rawal, Swati; Sinha, R. K.
2016-06-01
In the present paper, we have carried out analysis of asymmetric light propagation in a chirped photonic crystal waveguide. The designed structures have hexagonal arrangement and square arrangement of silicon rods in air substrate. Dimensions of the defect rods are tailored, so that the proposed design structure works as an optical isolator. The transmission analysis of the structure reveals that it can act as an optical diode. We have plotted the extinction ratio and transmission analysis graphs for the structure, and it has been observed that the maximum output is obtained for telecom wavelength of 1.55 μm. Dispersion curves are obtained using the plane wave expansion method, and the transmission is simulated using finite element method. The proposed structures are applicable for photonic integrated circuits due to their simple and clear operating principle.
Some analytic results in coherent quantum transport
Mardaani, Mohammad; Esfarjani, Keivan
2004-01-01
A quantum wire of uniform cross section (but with eventual disorder) with three regions: dot, left lead, and right lead, is considered. Assuming that the same unitary transformation diagonalizes all unit cells of this wire, we propose a new formula for the calculation of the Greens function (GF) and the coherent transmission coefficient. This formula allows to calculate these quantitites much faster than the standard methods. In particular, the problem of a uniform dot (simple cubic uniform d...
Chromatic Dispersion Estimation in Digital Coherent Receivers
Soriano, Ruben Andres; Hauske, Fabian N.; Guerrero Gonzalez, Neil;
2011-01-01
Polarization-diverse coherent demodulation allows to compensate large values of accumulated linear distortion by digital signal processing. In particular, in uncompensated links without optical dispersion compensation, the parameter of the residual chromatic dispersion (CD) is vital to set the...... according digital filtering function. We present different non-data-aided (blind) CD estimation methods for single-carrier transmission under implementation constraint conditions such as bandwidth limitation and sampling rate. The estimation performance for various modulation formats is compared with...
Coherent electron transport in a helical nanotube
Liang, Guo-Hua; Wang, Yong-long(Department of Physics, Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Nanjing University, 210093, Nanjing, China); Du, Long; Jiang, Hua; Kang, Guang-Zhen; Zong, Hong-shi(Department of Physics, Nanjing University, Nanjing 210093, China)
2016-01-01
The quantum dynamics of carriers bound to helical tube surfaces is investigated in a thin-layer quantization scheme. By numerically solving the open-boundary Schr$\\ddot{\\rm o}$dinger equation in curvilinear coordinates, geometric effect on the coherent transmission spectra is analysed in the case of single propagating mode as well as multimode. It is shown that, the coiling endows the helical nanotube with different transport properties from a bent cylindrical surface. Fano resonance appears ...
Asymmetric cointegration between exchange rate and trade balance in Nigeria
Alhaji Jibrilla Aliyu
2015-12-01
Full Text Available This paper empirically examines the long-run pass through of the official exchange rates into trade balance in Nigeria by means of threshold cointegration and asymmetric error correction modeling. The study provides evidence for non-linear cointegration between our variables of interest. The estimated asymmetric error correction models provide new evidence for slower transmission of exchange rate depreciations into the country’s trade balance, which in turn appears to offer partial support for the Dutch disease hypothesis. This finding suggests that policy-makers cannot hope to use currency devaluation to improve the trade balance. It is recommended that policy-makers focus attention on diversification of the economy away from dependence on crude oil exports into productive manufacturing and non-oil exports, which will be vital in making the economy more competitive.
Electron beam coherence measurements using diffracted beam interferometry/holography.
Herring, Rodney A
2009-06-01
The intensity and coherence of elastically and inelastically scattered electrons have been studied by the interference of electron-diffracted beams using a method of diffracted beam interferometry/holography (DBI/H). In the interferograms produced, fringes were found to exist from low to high scattering angles. The intensity and coherence of the fringes are useful for understanding the contrast mismatch between experimental and simulated images found in atomic resolution images of crystals produced by transmission electron microscopy (TEM) and annular dark-field (ADF) scanning transmission electron microscopy (STEM). The fringes disappear when the interfering beams are separated from an exact overlay position, which produces a measurement of the beam's lateral coherence and holds promise for measuring the coherence of the respective quasi-particles associated with the energy loss electrons. PMID:19141592
Catalytic coherence transformations
Bu, Kaifeng; Singh, Uttam; Wu, Junde
2016-04-01
Catalytic coherence transformations allow the otherwise impossible state transformations using only incoherent operations with the aid of an auxiliary system with finite coherence that is not being consumed in any way. Here we find the necessary and sufficient conditions for the deterministic and stochastic catalytic coherence transformations between a pair of pure quantum states. In particular, we show that the simultaneous decrease of a family of Rényi entropies of the diagonal parts of the states under consideration is a necessary and sufficient condition for the deterministic catalytic coherence transformations. Similarly, for stochastic catalytic coherence transformations we find the necessary and sufficient conditions for achieving a higher optimal probability of conversion. We thus completely characterize the coherence transformations among pure quantum states under incoherent operations. We give numerous examples to elaborate our results. We also explore the possibility of the same system acting as a catalyst for itself and find that indeed self-catalysis is possible. Further, for the cases where no catalytic coherence transformation is possible we provide entanglement-assisted coherence transformations and find the necessary and sufficient conditions for such transformations.
García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.
2009-05-01
In this Letter we define a family of entanglement distribution protocols assisted by feedback classical communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This leads to the definition of a new entanglement distribution capacity that exceeds the unassisted capacity for some interesting channels.
Zheng, Yanping
2009-01-01
In the thesis a coherent text is defined as a continuity of senses of the outcome of combining concepts and relations into a network composed of knowledge space centered around main topics. And the author maintains that in order to obtain the coherence of a target language text from a source text during the process of translation, a translator can…
Properties of the system of generalized coherent states for the simpliest Lie groups are reviewed. Coherent states for the group of rotations of the three-dimensional space SO(3) and the structure of the group are considered. Irreducible unitary representations of the SU(2) group are plotted, as well as a contineous series of concepts of the SU(1, 1) group
García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.
2008-01-01
In this letter we define a family of entanglement distribution protocols assisted by feedback classical communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well known coherent information. This lead to the definition of a new entanglement distribution capacity that exceeds the unassisted capacity for some interesting channels.
Partially coherent ultrafast spectrography
Bourassin-Bouchet, C.; Couprie, M.-E.
2015-01-01
Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter. PMID:25744080
Optical Code Generating Device Using 1×N Asymmetric Hollow Waveguide Couplers
Abang Annuar EHSAN; Sahbudin SHAARI; Mohd Kamil ABD.RAHMAN; Kee Mohd Rafique KEE ZAINAL ABIDIN
2008-01-01
An optical code generating device for security access system application is presented. The code generating device constructed using asymmetric hollow optical waveguide coupler design provides a unique series of output light intensities which are successively used as an optical code. The design of the waveguide is made using two major components which are asymmetric Y-junction splitter and a linear taper. Waveguiding is done using a hollow waveguide structure. Construction of higher level 1×N hollow waveguide coupler is done utilizing a basic 1×2 asymmetric waveguide coupler design together with a cascaded design scheme. Non-sequential ray tracing of the asymmetric hollow optical waveguide couplers is performed to predict the optical transmission properties of the waveguide. A representation of the code combination that can be generated from the device is obtained using combinatory number theory.
Asymmetric error correction models for the oil-gasoline price relationship
The existing literature on price asymmetries does not systematically investigate the sensitivity of the empirical results to the choice of a particular econometric specification. This paper fills this gap by providing a detailed comparison of the three most popular models designed to describe asymmetric price behavior, namely asymmetric ECM, autoregressive threshold ECM and ECM with threshold cointegration. Each model is estimated on a common monthly data set for the gasoline markets of France, Germany, Italy, Spain and UK over the period 1985-2003. All models are able to capture the temporal delay in the reaction of retail prices to changes in spot gasoline and crude oil prices, as well as some evidence of asymmetric behavior. However, the type of market and the number of countries which are characterized by asymmetric oil-gasoline price relations vary across models. The asymmetric ECM prescribes that long-run price asymmetries are most likely to be found in the second stage of the transmission chain. Conversely, the ECM with threshold cointegration suggests that long-run price asymmetries vary across countries and markets. Short-run price asymmetries are captured by the asymmetric ECM specification and the TAR-ECM. The latter model suggests that all European countries are likely to be affected by asymmetries at the distribution stage, while the results obtained with the asymmetric ECM are mixed
Cyclodextrins in Asymmetric and Stereospecific Synthesis
Fliur Macaev
2015-09-01
Full Text Available Since their discovery, cyclodextrins have widely been used as green and easily available alternatives to promoters or catalysts of different chemical reactions in water. This review covers the research and application of cyclodextrins and their derivatives in asymmetric and stereospecific syntheses, with their division into three main groups: (1 cyclodextrins promoting asymmetric and stereospecific catalysis in water; (2 cyclodextrins’ complexes with transition metals as asymmetric and stereospecific catalysts; and (3 cyclodextrins’ non-metallic derivatives as asymmetric and stereospecific catalysts. The scope of this review is to systematize existing information on the contribution of cyclodextrins to asymmetric and stereospecific synthesis and, thus, to facilitate further development in this direction.
Liu, Zhen-Fei [Molecular Foundry and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Neaton, Jeffrey B. [Molecular Foundry and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States); Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720 (United States)
2014-10-07
The electronic structure of organic-inorganic interfaces often features resonances originating from discrete molecular orbitals coupled to continuum lead states. An example is molecular junction, individual molecules bridging electrodes, where the shape and peak energy of such resonances dictate junction conductance, thermopower, I-V characteristics, and related transport properties. In molecular junctions where off-resonance coherent tunneling dominates transport, resonance peaks in the transmission function are often assumed to be Lorentzian functions with an energy-independent broadening parameter Γ. Here we define a new energy-dependent resonance broadening function, Γ(E), based on diagonalization of non-Hermitian matrices, which can describe resonances of a more complex, non-Lorentzian nature and can be decomposed into components associated with the left and right leads, respectively. We compute this quantity via an ab initio non-equilibrium Green's function (NEGF) approach based on density functional theory (DFT) for both symmetric and asymmetric molecular junctions, and show that our definition of Γ(E), when combined with Breit-Wigner formula, reproduces the transmission calculated from DFT-NEGF. Through a series of examples, we illustrate how this approach can shed new light on experiments and understanding of junction transport properties in terms of molecular orbitals.
The electronic structure of organic-inorganic interfaces often features resonances originating from discrete molecular orbitals coupled to continuum lead states. An example is molecular junction, individual molecules bridging electrodes, where the shape and peak energy of such resonances dictate junction conductance, thermopower, I-V characteristics, and related transport properties. In molecular junctions where off-resonance coherent tunneling dominates transport, resonance peaks in the transmission function are often assumed to be Lorentzian functions with an energy-independent broadening parameter Γ. Here we define a new energy-dependent resonance broadening function, Γ(E), based on diagonalization of non-Hermitian matrices, which can describe resonances of a more complex, non-Lorentzian nature and can be decomposed into components associated with the left and right leads, respectively. We compute this quantity via an ab initio non-equilibrium Green's function (NEGF) approach based on density functional theory (DFT) for both symmetric and asymmetric molecular junctions, and show that our definition of Γ(E), when combined with Breit-Wigner formula, reproduces the transmission calculated from DFT-NEGF. Through a series of examples, we illustrate how this approach can shed new light on experiments and understanding of junction transport properties in terms of molecular orbitals
Stable walking with asymmetric legs
Asymmetric leg function is often an undesired side-effect in artificial legged systems and may reflect functional deficits or variations in the mechanical construction. It can also be found in legged locomotion in humans and animals such as after an accident or in specific gait patterns. So far, it is not clear to what extent differences in the leg function of contralateral limbs can be tolerated during walking or running. Here, we address this issue using a bipedal spring-mass model for simulating walking with compliant legs. With the help of the model, we show that considerable differences between contralateral legs can be tolerated and may even provide advantages to the robustness of the system dynamics. A better understanding of the mechanisms and potential benefits of asymmetric leg operation may help to guide the development of artificial limbs or the design novel therapeutic concepts and rehabilitation strategies.
Dirac Particle for the Position Dependent Mass in the Generalized Asymmetric Woods-Saxon Potential
Soner Alpdoğan
2014-01-01
Full Text Available The one-dimensional Dirac equation with position dependent mass in the generalized asymmetric Woods-Saxon potential is solved in terms of the hypergeometric functions. The transmission and reflection coefficients are obtained by considering the one-dimensional electric current density for the Dirac particle and the equation describing the bound states is found by utilizing the continuity conditions of the obtained wave function. Also, by using the generalized asymmetric Woods-Saxon potential solutions, the scattering states are found out without making calculation for the Woods-Saxon, Hulthen, cusp potentials, and so forth, which are derived from the generalized asymmetric Woods-Saxon potential and the conditions describing transmission resonances and supercriticality are achieved. At the same time, the data obtained in this work are compared with the results achieved in earlier studies and are observed to be consistent.
Asymmetrically coupled directed percolation systems
Noh, Jae Dong; Park, Hyunggyu
2005-01-01
We introduce a dynamical model of coupled directed percolation systems with two particle species. The two species $A$ and $B$ are coupled asymmetrically in that $A$ particles branch $B$ particles whereas $B$ particles prey on $A$ particles. This model may describe epidemic spreading controlled by reactive immunization agents. We study nonequilibrium phase transitions with focused attention to the multicritical point where both species undergo the absorbing phase transition simultaneously. In ...
Asymmetric information and macroeconomic dynamics
Hawkins, Raymond J.; Aoki, Masanao; Roy Frieden, B.
2010-09-01
We show how macroeconomic dynamics can be derived from asymmetric information. As an illustration of the utility of this approach we derive the equilibrium density, non-equilibrium densities and the equation of motion for the response to a demand shock for productivity in a simple economy. Novel consequences of this approach include a natural incorporation of time dependence into macroeconomics and a common information-theoretic basis for economics and other fields seeking to link micro-dynamics and macro-observables.
Entrepreneurship, Asymmetric Information and Unemployment
Robin Boadway; Nicolas Marceau; Maurice Marchand; Marianne Vigneault
1998-01-01
We examine how three sources of asymmetric information affect the supply of entrepreneurs and unemployment. In the first case, banks cannot observe entrepreneurs' risk of failure so ration credit. This increases the number of entrepreneurs and the level of unemployment. In the second case, firms cannot observe workers' effort so offer a wage above the market clearing one. This results in unemployment and too few entrepreneurs. The final case arises when firms cannot observe workers' abilities...
Asymmetric Microscopic Driving Behavior Theory
Yeo, Hwasoo
2008-01-01
Numerous theories on traffic have been developed as traffic congestion gains more and more interest in our daily life. To model traffic phenomena, many traffic theorists have adopted theories from other fields such as fluid mechanics and thermodynamics. However, their efforts to model the traffic at a microscopic level have not been successful yet. Therefore, to overcome the limitations of the existing theories we propose a microscopic asymmetric traffic theory based on analysis of individual...
Effciency Concern under Asymmetric Information
Winschel, Evguenia; Zahn, Philipp
2012-01-01
Experimental evidence from simple distribution games supports the view that some individuals have a concern for the effciency of allocations. This motive could be important for the implementation of economic policy proposals. In a typical lab experiment, however, individuals have much more information available than outside the lab. We conduct a lab experiment to test whether asymmetric information influences prosocial behavior in a simple non-strategic interaction. In our setting, a dictator...
Cooperative emission of a coherent superflash of light
Kwong, Chang Chi; Pramod, Mysore S; Pandey, Kanhayia; Delande, Dominique; Pierrat, Romain; Wilkowski, David
2014-01-01
We investigate the transient coherent transmission of light through an optically thick cold strontium gas. We observe a coherent superflash just after an abrupt probe extinction, with peak intensity more than 3 times the incident one. We show that this coherent superflash is a direct signature of the cooperative forward scattering emission of the atoms induced by the probe in the stationary regime. Thus, surprisingly we find that the forward scattering amplitude can be larger than the incident probe excitation amplitude. By engineering fast transient phenomena on the incident field, we give a clear and simple picture of the physical mechanisms at play.
Asymmetric Wettability Directs Leidenfrost Droplets
Agapov, Rebecca L [ORNL; Boreyko, Jonathan B [ORNL; Briggs, Dayrl P [ORNL; Srijanto, Bernadeta R [ORNL; Retterer, Scott T [ORNL; Collier, Pat [ORNL; Lavrik, Nickolay V [ORNL
2014-01-01
Leidenfrost phenomena on nano- and microstructured surfaces are of great importance for increasing control over heat transfer in high power density systems utilizing boiling phenomena. They also provide an elegant means to direct droplet motion in a variety of recently emerging fluidic systems. Here, we report the fabrication and characterization of tilted nanopillar arrays (TNPAs) that exhibit directional Leidenfrost water droplets under dynamic conditions, namely on impact with Weber numbers 40 at T 325 C. The batch fabrication of the TNPAs was achieved by glancing-angle anisotropic reactive ion etching of a thermally dewet platinum mask, with mean pillar diameters of 100 nm and heights of 200-500 nm. In contrast to previously implemented macro- and microscopic Leidenfrost ratchets, our TNPAs induce no preferential directional movement of Leidenfrost droplets under conditions approaching steady-state film boiling, suggesting that the observed droplet directionality is not a result of asymmetric vapor flow. Using high-speed imaging, phase diagrams were constructed for the boiling behavior upon impact for droplets falling onto TNPAs, straight nanopillar arrays, and smooth silicon surfaces. The asymmetric impact and directional trajectory of droplets was exclusive to the TNPAs for impacts corresponding to the transition boiling regime, revealing that asymmetric wettability upon impact is the mechanism for the droplet directionality.
Coherent dynamics in semiconductors
Hvam, Jørn Märcher
1998-01-01
Ultrafast nonlinear optical spectroscopy is used to study the coherent dynamics of optically excited electron-hole pairs in semiconductors. Coulomb interaction implies that the optical inter-band transitions are dominated, at least at low temperatures, by excitonic effects. They are further...... enhanced in quantum confined lower-dimensional systems, where exciton and biexciton effects dominate the spectra even at room temperature. The coherent dynamics of excitons are at modest densities well described by the optical Bloch equations and a number of the dynamical effects known from atomic and...... as a tool to study the coherent exciton dynamics, and the importance of performing transform limited spectroscopy is demonstrated throughout....
Coherent diffractive ρ production
Coherent diffractive ρ production by neutrinos occurs at low four-momentum transfer and high energy transfer. These interactions are generally understood to occur via the coupling of the weak charged current to the vector meson, which scatters diffractively from the target nucleus. Since coherent events are those in which the nucleus interacts as a whole, ie without breakup, and with small recoil energy, these events have a very sharp |t|-distribution. This presentation deals mostly with the Monte Carlo simulation of the coherent diffractive production of the ρ production and in particular with the reconstruction algorithm (description and efficiency) and the |t| distribution
Michael Thomas
2005-01-01
@@ What makes a coherent EFL curriculum? How can curriculum planners avoid a mismatch between policy and pragmatics to produce an effective decision-making process? In The Second Language Curriculum, Johnson describes the coherent curriculum as one in which decision outcomes from the various stages of development are mutually consistent and complementary,and learning outcomes reflect curriculum aims.The achievement of coherence is said to depend crucially in most educational contexts upon the formalisation of decision-making processes and products. This formalisation facilitates consensus among those involved and is a prerequisite for effective evaluation and subsequent renewal (1994: xiii)
Control of transformerless MMC-HVDC during asymmetric grid faults
Timofejevs, Artjoms; Gamboa, Daniel; Liserre, Marco;
2013-01-01
Modular multilevel converter (MMC) is the latest converter topology suitable for the transformerless applications in HVDC transmission. HVDC systems are required to remain connected during grid faults, provide grid support and completely decouple the healthy side from the faulty one. The MMC...... converter weak points are challenged by this particular condition and by these demands. This paper demonstrates the effect of negative and zero sequence current control in MMCHVDC during asymmetric grid faults. A current limitation strategy for MMC is derived and verified through simulations....
Han, Shengqian; Bengtsson, Mats
2010-01-01
Base station cooperative transmission, which is also known as coordinated multi-point (CoMP) transmission, is a promising technique to improve spectrum efficiency in future cellular systems. However, they need large signalling overhead to gather the channel information. In this paper, we consider low feedback user scheduling in downlink coherent CoMP systems exploiting their inherent channel asymmetry. Through the analysis of the statistics of the angle between channel vectors and the tightness of a lower bound of the orthogonally projected norm, we show that channel norm provides sufficient information to judge the orthogonality among users in asymmetric channels. Based on this observation, we propose a channel norm-based user scheduler (NUS), a local channel aided NUS (LocalNUS) and a large-scale fading-based user scheduler (LUS). Simulation results show that the LocalNUS performs very close to the existing greedy user scheduler (GUS) and semi-orthogonal user scheduler (SUS) with full channel state informat...
ASYMMETRICALLY SECURED EGMP OVER MANET’S
Sayed Mohammed Raja
2013-06-01
Full Text Available Group communications are significant in Mobile Ad hoc Networks (MANET. Multicast is an wellorganized technique for applying group communications. Yet, it is interesting to implement effective andaccessible multicast in MANET due to the effort in group member management and multicasting of packets forwarding in an active topology. We suggest a Asymmetrically Secured novel Efficient Geographic Multicast Protocol (EGMP. EGMP uses a practical-zone-based arrangement to implement accessible and effective groupmember management. A network-wide zone-based bi-directional tree is made to attain more well-organized member management and multicast delivery. The location information is used to monitor the zone structure, multicast tree building and multicast packets forwarding, which capably reduce the overhead for route finding and tree structure maintenance. Some approaches have been suggested to further improvement in the efficiency of the protocol, for example, presenting the concept of zone depth for construction an ideal tree structure and adding the position search of group of members with the ordered group member management. To switch empty zone problem met by most routing protocols using a zone structure. Finally, we plan a pattern to switch the security problem faced by the multicasting. The scalability and the productivity of EGMP are assessed through simulations and quantitative analysis. Our results prove that EGMP has great packet delivery ratio, and low control overhead, and is accessible to both group size and network size. EGMP has expressively lower control overhead, data transmission overhead, and multicast group joining delay.
Coherence in Industrial Transformation
Jørgensen, Ulrik; Lauridsen, Erik Hagelskjær
2003-01-01
The notion of coherence is used to illustrate the general finding, that the impact of environmental management systems and environmental policy is highly dependent of the context and interrelatedness of the systems, procedures and regimes established in society....
Bromley, Thomas R; Adesso, Gerardo
2014-01-01
We analyse under which dynamical conditions the coherence of an open quantum system is totally unaffected by noise. For a single qubit, specific measures of coherence are found to freeze under different conditions, with no general agreement between them. Conversely, for an N-qubit system with even N, we identify universal conditions in terms of initial states and local incoherent channels such that all bona fide distance-based coherence monotones are left invariant during the entire evolution. This finding also provides an insightful physical interpretation for the freezing phenomenon of quantum correlations beyond entanglement. We further obtain analytical results for distance-based measures of coherence in two-qubit states with maximally mixed marginals.
... Cardiac Magnetic Resonance Imaging (MRI and MRA) Computed Tomography (CT) Scan Diagnostic Tests and Procedures Echocardiography Electrocardiogram ... Ultrasound Nuclear Stress Test Nuclear Ventriculography Positron Emission Tomography (PET) Stress ... Optical Coherence Tomography | ...
Thomson, D. J.; Maclennan, C. G.; Lanzerotti, L. J.
2006-12-01
The EPAM charged particle instrument on ACE is the backup for the HISCALE instrument on Ulysses making the two ideally suited for spatial coherence studies over large heliosphere distances. Fluxes of low-energy ( ~50 - 200 keV) electrons are detected in eight spatial sectors on both spacecraft. A spherical harmonic description of the particle flux as a function of time using only the l=0 and l=1 degree coefficients describes most of the observed flux. Here we concentrate on the three l=1 coefficients for the 60--100 kev electrons.Between the two spacecraft these result in nine coherence estimates that are all typically moderately coherent, but the fact that the different coefficients at each spacecraft are also coherent with each other makes interpretation difficult. To avoid this difficulty we estimated the canonical coherences between the two groups of three series. This, in effect, chooses an optimum coordinate system at each spacecraft and for each frequency and estimates the coherence in this frame. Using one--minute data, we find that the canonical coherences are generally larger at high frequencies (3 mHz and above) than they are at low frequencies. This appears to be generally true and does not depend particularly on time, range, etc. However, if the data segment is chosen too long, say > 30 days with 1--minute sampling, the coherence at high frequencies drops. This may be because the spatial and temporal features of the mode are confounded, or possibly because the solar modes p--modes are known to change frequency with solar activity, so do not appear coherent on long blocks.The coherences are not smooth functions of frequency, but have a bimodal distribution particularly in the 100 μHz to 5 mHz range. Classifying the data at frequencies where the canonical coherences are high in terms of apparent polarization and orientation, we note two major families of modes that appear to be organized by the Parker spiral. The magnetic field data on the two
Partially coherent ultrafast spectrography
Bourassin-Bouchet, C.; Couprie, M.-E.
2015-01-01
Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse c...
We have carried out high-resolution single-pulse coherent diffractive imaging at the FLASH free-electron laser. The intense focused FEL pulse gives a high-resolution low-noise coherent diffraction pattern of an object before that object turns into a plasma and explodes. In particular we are developing imaging of biological specimens beyond conventional radiation damage resolution limits, developing imaging of ultrafast processes, and testing methods to characterize and perform single-particle imaging.
Spohn, Wolfgang
1999-01-01
The paper proposes two principles of coherence (thus taking up work started in Spohn (1991) "A Reason for Explanation: Explanations Provide Stable Reasons"). The latter indeed serves as a weak, but precise explication of the notion of coherence as it is used in the current epistemological discussion. After discussing their epistemological setting, the paper considers four ways of establishing these principles. They may be inferred neither from enumerative induction, nor from the nature of pro...
A J Seeds; Fice, M. J.; Balakier, K; M Natrella; Mitrofanov, O.; Pepper, M.; Renaud, C.C.; M. Lamponi; M Chtioui; Van Dijk, F.; Aeppli, G.; A G Davies; Dean, P.; Linfield, E
2013-01-01
We present a review of recent developments in THz coherent systems based on photonic local oscillators. We show that such techniques can enable the creation of highly coherent, thus highly sensitive, systems for frequencies ranging from 100 GHz to 5 THz, within an energy efficient integrated platform. We suggest that such systems could enable the THz spectrum to realize its full applications potential. To demonstrate how photonics-enabled THz systems can be realized, we review the performance...
Yanping Zheng
2009-01-01
In the thesis a coherent text is defined as a continuity of senses of the outcome of combining concepts and relations into a network composed of knowledge space centered around main topics. And the author maintains that in order to obtain the coherence of a target language text from a source text during the process of translation, a translator can utilize the following approaches: retention of the continuity of senses of a text; reconstruction of the target text for the purpose of continuity;...
Saorín, Manuel
2016-01-01
We show that, under particular conditions, if a t-structure in the unbounded derived category of a locally coherent Grothendieck category restricts to the bounded derived category of its category of finitely presented objects, then its heart is itself a locally coherent Grothendieck category. Those particular conditions are always satisfied when the Grothendieck category is arbitrary and one considers the t-structure associated to a torsion pair in the category of finitely presented objects. ...
Coherence vortices of partially coherent beams in the far field
Liu Pu-Sheng; Lü Bai-da
2007-01-01
Based on the propagation law of cross-spectral density function, studied in this paper are the coherence vortices of partially coherent, quasi-monochromatic singular beams with Gaussian envelope and Schell-model correlator in the far field, where our main attention is paid to the evolution of far-field coherence vortices into intensity vortices of fully coherent beams. The results show that, although there are usually no zeros of intensity in partially coherent beams with Gaussian envelope and Schell-model correlator, zeros of spectral degree of coherence exist. The coherence vortices of spectral degree of coherence depend on the relative coherence length, mode index and positions of pairs of points.If a point and mode index are kept fixed, the position of coherence vortices changes with the increase of the relative coherence length. For the low coherent case there is a circular phase dislocation. In the coherent limit coherence vortices become intensity vortices of fully coherent Laguerre-Gaussian beams.
... Abroad Treatment Basic Statistics Get Tested Find an HIV testing site near you. Enter ZIP code or city Follow HIV/AIDS CDC HIV CDC HIV/AIDS See RSS | ... on HIV Syndicated Content Website Feedback HIV/AIDS HIV Transmission Language: English Español (Spanish) Recommend on Facebook ...
Ding, Guilin; Lü, Baida
2002-03-01
The generalized Huygens-Fresnel diffraction integral for misaligned asymmetric first-order optical systems is derived by using the canonical operator method, which enables us to study propagation properties of anisotropic Gaussian Schell-model (AGSM) beams through misaligned asymmetric first-order optical systems. It is shown that under the action of misaligned asymmetric first-order optical systems AGSM beams do not preserve the closed property. Therefore generalized partially coherent anisotropic Gaussian Schell-model beams called decentered anisotropic Gaussian Schell-model (DAGSM) beams are introduced, and AGSM beams can be regarded as a special case of DAGSM beams. PMID:11876311
Incompressibility of asymmetric nuclear matter
Using an isospin- and momentum-dependent modified Gogny (MDI) interaction, the Skyrme-Hartree-Fock (SHF) approach, and a phenomenological modified Skyrme-like (MSL) model, we have studied the incompressibility Ksat(δ) of isospin asymmetric nuclear matter at its saturation density. Our results show that in the expansion of Ksat(δ) in powers of isospin asymmetry δ, i.e., Ksat(δ) = K0 + Ksat,2δ2 + Ksat,4δ4 + O(δ6), the magnitude of the 4th-order Ksat,4 parameter is generally small. The 2nd-order Ksat,2 parameter thus essentially characterizes the isospin dependence of the incompressibility of asymmetric nuclear matter at saturation density. Furthermore, the Ksat,2 can be expressed as Ksat,2 = Ksym – 6L – J0/K0 L in terms of the slope parameter L and the curvature parameter Ksym of the symmetry energy and the third-order derivative parameter J0 of the energy of symmetric nuclear matter at saturation density, and we find the higher order J0 contribution to Ksat,2 generally cannot be neglected. Also, we have found a linear correlation between Ksym and L as well as between J0/K0 and K0. Using these correlations together with the empirical constraints on K0 and L, the nuclear symmetry energy Esym(ρ0) at normal nuclear density, and the nucleon effective mass, we have obtained an estimated value of Ksat,2 = -370 ± 120 MeV for the 2nd-order parameter in the isospin asymmetry expansion of the incompressibility of asymmetric nuclear matter at its saturation density. (author)
Asymmetric Information and Consumer Demand
Ismagilova G. N.; Danilina E. I.; Gafurov I. R.; Ismagilov R. I.; Safiullin L. N.
2014-01-01
In the paper study the peculiarities of the formation the consumer demand for durable goods, the so-called «experience goods» in markets with asymmetric information. In the known literature sources studying of the demand is based on the assumption that at the moment of the purchase of goods and services people know exactly what price they are willing to pay for them and what utility they are going to obtain using those goods and services. Consider the signal model in which the initial price a...
Transient Stability During Asymmetrical Faults
Couturier, Nicolas
2015-01-01
This research project has been conducted at RTE in order to study the transient stability after asymmetrical faults. When three-phase short-circuits occur in a network, almost all the electrical power is lost on the relevant line(s). Among all short-circuit types, it is the most drastic event and the issue has to be solved very quickly. But oddly, it is also the easiest problem to solve mathematically speaking. This comes from the fact that the system stays balanced, and equations can be simp...
Phase equilibria in asymmetric mixtures
The simplified version of the Perturbed Hard-Chain Theory (SPHCT) is used to compute the phase equilibria and Henry's constants for mixtures in which the molecules are highly asymmetric both in shape and in the intermolecular potential. These mixtures include binary systems such as CO2/hydrocarbons and hydrocarbons/hydrocarbons, which are of particular interest for the oil industry. For this type of mixtures a single parameter (which is calculated from available experimental data of liquid-vapor equilibrium) is introduced. The approach yields results which compare well with the experimental behavior reported in the literature (Author)
Generation of infrared entangled light in asymmetric semiconductor quantum wells
Lü, Xin-You; Wu, Jing; Zheng, Li-Li; Huang, Pei
2010-12-01
We proposed a scheme to achieve two-mode CV entanglement with the frequencies of entangled modes in the infrared range in an asymmetric semiconductor double-quantum-wells (DQW), where the required quantum coherence is obtained by inducing the corresponding intersubband transitions (ISBTs) with a classical field. By numerically simulating the dynamics of system, we show that the entanglement period can be prolonged via enhancing the intensity of classical field, and the generation of entanglement doesn't depend intensively on the initial condition of system in our scheme. Moreover, we also show that a bipartite entanglement amplifier can be realized in our scheme. The present research provides an efficient approach to achieve infrared entangled light in the semiconductor nanostructure, which may have significant impact on the progress of solid-state quantum information theory.
Orientation Dynamics of Asymmetric Rotors Using Random Phase Wave Functions
Kallush, Shimshon
2015-01-01
Intense terahertz-frequency pulses induce coherent rotational dynamics and orientation of polar molecular ensembles. Exact numerical methods for rotational dynamics are computationally not feasible for the vast majority of molecular rotors - the asymmetric top molecules at ambient temperatures. We exemplify the use of Random Phase Wave Functions (RPWF) by calculating the terahertz-induced rotational dynamics of sulfur dioxide (SO2) at ambient temperatures and high field strengths and show that the RPWF method gains efficiency with the increase in temperature and in the THz-field strengths. The presented method provides wide-ranging computational access to rotational dynamical responses of molecules at experimental conditions which are far beyond the reach of exact numerical methods.
Tripartite fully asymmetric universal quantum cloning
Full text: We investigate the universal asymmetric cloning of states in a Hilbert space of arbitrary dimension d. We derive the class of optimal and fully asymmetric universal 1 → 3 cloners, which produce three copies, each having a different fidelity. A simple parametric expression for the maximum achievable cloning fidelity triplets will be provided. As a side-product, we also prove the optimality of the 1 → 2 asymmetric cloning machines that have been proposed in the literature. (author)
Enhanced Asymmetric Bilinear Model for Face Recognition
Wenjuan Gong; Weishan Zhang; Jordi Gonzàlez; Yan Ren; Zhen Li
2015-01-01
Bilinear models have been successfully applied to separate two factors, for example, pose variances and different identities in face recognition problems. Asymmetric model is a type of bilinear model which models a system in the most concise way. But seldom there are works exploring the applications of asymmetric bilinear model on face recognition problem with illumination changes. In this work, we propose enhanced asymmetric model for illumination-robust face recognition. Instead of initiali...
Fano resonance of an asymmetric dielectric wire pair
Zhang, Fuli; Huang, XinChao; Zhao, Qian; Chen, Lei; Wang, Ying; Li, Qiang; He, Xuan; Li, Chang; Chen, Ke
2014-10-01
We experimentally demonstrate Fano resonance in a metamaterial composed of an asymmetric ferroelectric wire pair. By assembling two parallel ceramic wires of different lengths, sharp Fano-type transmission spectra emerge as a result of interference between the quadrupole and dipole modes. A rapid increase in group delay is observed as a result of a steep variation in transmission phase. The location of the Fano resonance peak depends on the wire separation and degree of asymmetry. Furthermore, Fano resonance can be thermally modulated from 9.8 GHz to 10.5 GHz as the ambient temperature varies from 10 °C to 50 °C, as a consequence of the temperature dependence of the permittivity of the ceramic material.
Fourier phase in Fourier-domain optical coherence tomography
Uttam, Shikhar; Liu, Yang
2015-01-01
Phase of an electromagnetic wave propagating through a sample-of-interest is well understood in the context of quantitative phase imaging in transmission-mode microscopy. In the past decade, Fourier-domain optical coherence tomography has been used to extend quantitative phase imaging to the reflection-mode. Unlike transmission-mode electromagnetic phase, however, the origin and characteristics of reflection-mode Fourier phase are poorly understood, especially in samples with a slowly varying...
Stimulated coherent transition radiation
Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed
On the wake flow of asymmetrically beveled trailing edges
Guan, Yaoyi; Pröbsting, Stefan; Stephens, David; Gupta, Abhineet; Morris, Scott C.
2016-05-01
Trailing edge and wake flows are of interest for a wide range of applications. Small changes in the design of asymmetrically beveled or semi-rounded trailing edges can result in significant difference in flow features which are relevant for the aerodynamic performance, flow-induced structural vibration and aerodynamically generated sound. The present study describes in detail the flow field characteristics around a family of asymmetrically beveled trailing edges with an enclosed trailing-edge angle of 25° and variable radius of curvature R. The flow fields over the beveled trailing edges are described using data obtained by particle image velocimetry (PIV) experiments. The flow topology for different trailing edges was found to be strongly dependent on the radius of curvature R, with flow separation occurring further downstream as R increases. This variation in the location of flow separation influences the aerodynamic force coefficients, which were evaluated from the PIV data using a control volume approach. Two-point correlations of the in-plane velocity components are considered to assess the structure in the flow field. The analysis shows large-scale coherent motions in the far wake, which are associated with vortex shedding. The wake thickness parameter yf is confirmed as an appropriate length scale to characterize this large-scale roll-up motion in the wake. The development in the very near wake was found to be critically dependent on R. In addition, high-speed PIV measurements provide insight into the spectral characteristics of the turbulent fluctuations. Based on the time-resolved flow field data, the frequency range associated with the shedding of coherent vortex pairs in the wake is identified. By means of time-correlation of the velocity components, turbulent structures are found to convect from the attached or separated shear layers without distinct separation point into the wake.
100-Gbps hybrid optical fiber-wireless transmission
Pang, Xiaodan; Caballero Jambrina, Antonio; Deng, Lei;
2013-01-01
We present experimental results on using optical transmission technologies such as I&Q modulators, digital coherent receivers, heterodyne up-conversion in fast photodiodes, to generate, transmit and detect high capacity wireless transmission. Both OFDM and QAM modulation formats are tested in the W-achieving...
Aberrations in asymmetrical electron lenses
Starting from well established knowledge in light-optics we explore the question if electron-optical aberration can be improved in asymmetrical electron lenses. We show that spherical as well as chromatic aberration coefficients are reduced in asymmetric electrostatic einzel lenses when the center electrode is moved away from the center position towards the entrance electrode. Relative improvements up to 40% for both the chromatic and the spherical aberration coefficients can be obtained. We use analytical and numerical calculations to confirm this result for exemplary cases of a lens with fixed length and working distance. The agreement of the two calculation methods is very good. We then derive an estimate for the electron-optical aberration coefficients from light-optics. The derived expressions for chromatic and spherical aberrations are somewhat simpler than the ones derived from electron-optics as they involve integrals only over the electrostatic potential, not over the electron paths. The estimated formulas still agree well with the electron optical calculations. Overall, we are tempted to suggest that the enormous knowledge base of light optics can provide considerable guidance for electron-optical applications. -- Highlights: ► Develops the analogy between light and electron optics in aberration calculations. ► Optimized spherical and chromatic aberrations for an electrostatic einzel lens. ► Comparison between analytic and numerical aberration calculations.
Aberrations in asymmetrical electron lenses.
Fitzgerald, J P S; Word, R C; Könenkamp, R
2012-08-01
Starting from well established knowledge in light-optics we explore the question if electron-optical aberration can be improved in asymmetrical electron lenses. We show that spherical as well as chromatic aberration coefficients are reduced in asymmetric electrostatic einzel lenses when the center electrode is moved away from the center position towards the entrance electrode. Relative improvements up to 40% for both the chromatic and the spherical aberration coefficients can be obtained. We use analytical and numerical calculations to confirm this result for exemplary cases of a lens with fixed length and working distance. The agreement of the two calculation methods is very good. We then derive an estimate for the electron-optical aberration coefficients from light-optics. The derived expressions for chromatic and spherical aberrations are somewhat simpler than the ones derived from electron-optics as they involve integrals only over the electrostatic potential, not over the electron paths. The estimated formulas still agree well with the electron optical calculations. Overall, we are tempted to suggest that the enormous knowledge base of light optics can provide considerable guidance for electron-optical applications. PMID:22206603
Excitons in asymmetric quantum wells
Grigoryev, P. S.; Kurdyubov, A. S.; Kuznetsova, M. S.; Ignatiev, I. V.; Efimov, Yu. P.; Eliseev, S. A.; Petrov, V. V.; Lovtcius, V. A.; Shapochkin, P. Yu.
2016-09-01
Resonance dielectric response of excitons is studied for the high-quality InGaAs/GaAs heterostructures with wide asymmetric quantum wells (QWs). To highlight effects of the QW asymmetry, we have grown and studied several heterostructures with nominally square QWs as well as with triangle-like QWs. Several quantum confined exciton states are experimentally observed as narrow exciton resonances. A standard approach for the phenomenological analysis of the profiles is generalized by introducing different phase shifts for the light waves reflected from the QWs at different exciton resonances. Good agreement of the phenomenological fit to the experimentally observed exciton spectra for high-quality structures allowed us to reliably obtain parameters of the exciton resonances: the exciton transition energies, the radiative broadenings, and the phase shifts. A direct numerical solution of the Schrödinger equation for the heavy-hole excitons in asymmetric QWs is used for microscopic modeling of the exciton resonances. Remarkable agreement with the experiment is achieved when the effect of indium segregation is taken into account. The segregation results in a modification of the potential profile, in particular, in an asymmetry of the nominally square QWs.
ASYMMETRIC SOLAR POLAR FIELD REVERSALS
The solar polar fields reverse because magnetic flux from decaying sunspots moves toward the poles, with a preponderance of flux from the trailing spots. If there is a strong asymmetry, in the sense that most activity is in the northern hemisphere, then that excess flux will move toward the north pole and reverse that pole first. If there is more activity in the south later on, then that flux will help to reverse the south pole. In this way, two humps in the solar activity and a corresponding difference in the time of reversals develop (in the ideal case). Such a difference was originally noted in the very first observation of polar field reversal just after the maximum of the strongly asymmetric solar cycle 19, when the southern hemisphere was most active before sunspot maximum and the south pole duly reversed first, followed by the northern hemisphere more than a year later, when that hemisphere became most active. Solar cycles since then have had the opposite asymmetry, with the northern hemisphere being most active before solar maximum. We show that polar field reversals for these cycles have all happened in the north first, as expected. This is especially noteworthy for the present solar cycle 24. We suggest that the association of two or more peaks of solar activity when separated by hemispheres with correspondingly different times of polar field reversals is a general feature of the cycle, and that asymmetric polar field reversals are simply a consequence of the asymmetry of solar activity.
Asymmetric Laguerre-Gaussian beams
Kovalev, A. A.; Kotlyar, V. V.; Porfirev, A. P.
2016-06-01
We introduce a family of asymmetric Laguerre-Gaussian (aLG) laser beams. The beams have been derived via a complex-valued shift of conventional LG beams in the Cartesian plane. While propagating in a uniform medium, the first bright ring of the aLG beam becomes less asymmetric and the energy is redistributed toward peripheral diffraction rings. The projection of the orbital angular momentum (OAM) onto the optical axis is calculated. The OAM is shown to grow quadratically with increasing asymmetry parameter of the aLG beam, which equals the ratio of the shift to the waist radius. Conditions for the OAM becoming equal to the topological charge have been derived. For aLG beams with zero radial index, we have deduced an expression to define the intensity maximum coordinates and shown the crescent-shaped intensity pattern to rotate during propagation. Results of the experimental generation and rotation of aLG beams agree well with theoretical predictions.