Noise spectroscopy of nanowire structures: fundamental limits and application aspects
Vitusevich, Svetlana; Zadorozhnyi, Ihor
2017-04-01
Nanowires (NWs) have recently emerged as a new class of materials demonstrating unique properties which may completely differ from their bulk counterparts. The main aim of this work is to give an overview of results on noise and fluctuation phenomena in NW-based structures. We emphasize that noise is one of the main parameters, which determines the characteristics of the device structures and sets the fundamental limits of the working principles and operation regimes of NWs as key electronic elements, including field-effect transistors (FETs). We review the studies focusing on the understanding of noise sources and the main application aspects of noise spectroscopy. Noise application aspects will provide information about the performance of core–shell NW structures, the gate-coupling effect and its advantages for detection of the useful signal with prospects to extract it from the noise level, random telegraph signal as a useful tool for enhanced sensitivity, novel components of noise reflecting dielectric polarization fluctuation processes and fluctuation phenomena as a sensitive tool for molecular charge dynamics in NW FETs. Moreover, noise spectroscopy assists understanding of electronic transport regimes and effects, transport peculiarities in topological materials and aspects reflecting Majorana bound states. Thus noise in NWs on the basis of Si, Ge, Si/Ge, GaAs, InAs, InGaAs, Au, GaAs/AlGaAs, GaAsSb, SnO2, GaN, ZnO, CuO, In2O3 and AlGaN/GaN materials reflects a great variety of phenomena and processes, information about their stability and reliability. It can be utilized for numerous different applications in nanoelectronics and bioelectronics.
Speckle phase noise in coherent laser ranging: fundamental precision limitations.
Baumann, Esther; Deschênes, Jean-Daniel; Giorgetta, Fabrizio R; Swann, William C; Coddington, Ian; Newbury, Nathan R
2014-08-15
Frequency-modulated continuous-wave laser detection and ranging (FMCW LADAR) measures the range to a surface through coherent detection of the backscattered light from a frequency-swept laser source. The ultimate limit to the range precision of FMCW LADAR, or any coherent LADAR, to a diffusely scattering surface will be determined by the unavoidable speckle phase noise. Here, we demonstrate the two main manifestations of this limit. First, frequency-dependent speckle phase noise leads to a non-Gaussian range distribution having outliers that approach the system range resolution, regardless of the signal-to-noise ratio. These outliers are reduced only through improved range resolution (i.e., higher optical bandwidths). Second, if the range is measured during a continuous lateral scan across a surface, the spatial pattern of speckle phase is converted to frequency noise, which leads to additional excess range uncertainty. We explore these two effects and show that laboratory results agree with analytical expressions and numerical simulations. We also show that at 1 THz optical bandwidth, range precisions below 10 μm are achievable regardless of these effects.
Generation-recombination noise: the fundamental sensitivity limit for kinetic inductance detectors
De Visser, P.J.; Baselmans, J.J.A.; Diener, P.; Yates, S.J.C.; Endo, A.; Klapwijk, T.M.
2012-01-01
We present measurements of quasiparticle generation-recombination noise in aluminium Microwave Kinetic Inductance Detectors, the fundamental noise source for these detectors. Both the quasiparticle lifetime and the number of quasiparticles can be determined from the noise spectra. The number of
Generation-recombination noise: the fundamental sensitivity limit for kinetic inductance detectors
De Visser, P.J.; Baselmans, J.J.A.; Diener, P.; Yates, S.J.C.; Endo, A.; Klapwijk, T.M.
2012-01-01
We present measurements of quasiparticle generation-recombination noise in aluminium Microwave Kinetic Inductance Detectors, the fundamental noise source for these detectors. Both the quasiparticle lifetime and the number of quasiparticles can be determined from the noise spectra. The number of quas
Fundamental Limits of Cooperation
Lozano, Angel; Andrews, Jeffrey G
2012-01-01
Cooperation is viewed as a key ingredient for interference management in wireless systems. This paper shows that cooperation has fundamental limitations. The main result is that even full cooperation between transmitters cannot in general change an interference-limited network to a noise-limited network. The key idea is that there exists a spectral efficiency upper bound that is independent of the transmit power. First, a spectral efficiency upper bound is established for systems that rely on pilot-assisted channel estimation; in this framework, cooperation is shown to be possible only within clusters of limited size, which are subject to out-of-cluster interference whose power scales with that of the in-cluster signals. Second, an upper bound is also shown to exist when cooperation is through noncoherent communication; thus, the spectral efficiency limitation is not a by-product of the reliance on pilot-assisted channel estimation. Consequently, existing literature that routinely assumes the high-power spect...
Fundamental Noise-Limited Optical Phase Locking at Femtowatt Light Levels
Dick, John; Tu, Meirong; Birnbaum, Kevin; Strekalov, Dmitry; Yu, Nan
2008-01-01
We describe an optical phase lock loop (PLL) designed to recover an optical carrier at powers below one picowatt in a Deep Space optical transponder. Previous low power optical phase lock has been reported with powers down to about 1 pW. We report the demonstration and characterization of the optical phase locking at femtowatt levels. We achieved a phase slip rate below one cycle-slip/second at powers down to 60 femtowatts. This phase slip rate corresponds to a frequency stability of 1 10(exp -14) at 1 s, a value better than any frequency standard available today for measuring times equal to a typical two-way delay between Earth and Mars. The PLL shows very robust stability at these power levels. We developed simulation software to optimize parameters of the second order PLL loop in the presence of laser flicker frequency noise and white phase (photon) noise, and verified the software with a white phase noise model by Viterbi. We also demonstrated precise Doppler tracking at femtowatt levels.
Hajdok, G; Battista, J J; Cunningham, I A
2008-07-01
A frequency-dependent x-ray Swank factor based on the "x-ray interaction" modulation transfer function and normalized noise power spectrum is determined from a Monte Carlo analysis. This factor was calculated in four converter materials: amorphous silicon (a-Si), amorphous selenium (a-Se), cesium iodide (CsI), and lead iodide (PbI2) for incident photon energies between 10 and 150 keV and various converter thicknesses. When scaled by the quantum efficiency, the x-ray Swank factor describes the best possible detective quantum efficiency (DQE) a detector can have. As such, this x-ray interaction DQE provides a target performance benchmark. It is expressed as a function of (Fourier-based) spatial frequency and takes into consideration signal and noise correlations introduced by reabsorption of Compton scatter and photoelectric characteristic emissions. It is shown that the x-ray Swank factor is largely insensitive to converter thickness for quantum efficiency values greater than 0.5. Thus, while most of the tabulated values correspond to thick converters with a quantum efficiency of 0.99, they are appropriate to use for many detectors in current use. A simple expression for the x-ray interaction DQE of digital detectors (including noise aliasing) is derived in terms of the quantum efficiency, x-ray Swank factor, detector element size, and fill factor. Good agreement is shown with DQE curves published by other investigators for each converter material, and the conditions required to achieve this ideal performance are discussed. For high-resolution imaging applications, the x-ray Swank factor indicates: (i) a-Si should only be used at low-energy (e.g., mammography); (ii) a-Se has the most promise for any application below 100 keV; and (iii) while quantum efficiency may be increased at energies just above the K edge in CsI and PbI2, this benefit is offset by a substantial drop in the x-ray Swank factor, particularly at high spatial frequencies.
Goryachev, Maxim; van Kann, Frank; Galliou, Serge; Tobar, Michael E
2014-01-01
Thermal Nyquist noise fluctuations of high-$Q$ Bulk Acoustic Wave (BAW) cavities have been observed at cryogenic temperatures with a DC Superconducting Quantum Interference Device (SQUID) amplifier. High $Q$ modes with bandwidths of few tens of milliHz produce thermal fluctuations with a Signal-To-Noise ratio of up to 23dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that the quality factor remains extremely high ($Q>10^8$ at low order overtones) for very weak (thermal) system motion at low temperatures, when compared to values measured with relatively strong external excitation. This result represents an enabling step towards operating such a high-Q acoustic device at the standard quantum limit.
Fundamental Limits to Cellular Sensing
ten Wolde, Pieter Rein; Becker, Nils B.; Ouldridge, Thomas E.; Mugler, Andrew
2016-03-01
In recent years experiments have demonstrated that living cells can measure low chemical concentrations with high precision, and much progress has been made in understanding what sets the fundamental limit to the precision of chemical sensing. Chemical concentration measurements start with the binding of ligand molecules to receptor proteins, which is an inherently noisy process, especially at low concentrations. The signaling networks that transmit the information on the ligand concentration from the receptors into the cell have to filter this receptor input noise as much as possible. These networks, however, are also intrinsically stochastic in nature, which means that they will also add noise to the transmitted signal. In this review, we will first discuss how the diffusive transport and binding of ligand to the receptor sets the receptor correlation time, which is the timescale over which fluctuations in the state of the receptor, arising from the stochastic receptor-ligand binding, decay. We then describe how downstream signaling pathways integrate these receptor-state fluctuations, and how the number of receptors, the receptor correlation time, and the effective integration time set by the downstream network, together impose a fundamental limit on the precision of sensing. We then discuss how cells can remove the receptor input noise while simultaneously suppressing the intrinsic noise in the signaling network. We describe why this mechanism of time integration requires three classes (groups) of resources—receptors and their integration time, readout molecules, energy—and how each resource class sets a fundamental sensing limit. We also briefly discuss the scheme of maximum-likelihood estimation, the role of receptor cooperativity, and how cellular copy protocols differ from canonical copy protocols typically considered in the computational literature, explaining why cellular sensing systems can never reach the Landauer limit on the optimal trade
Fundamental Imaging Limits of Radio Telescope Arrays
Wijnholds, Stefan J; 10.1109/JSTSP.2008.2004216
2010-01-01
The fidelity of radio astronomical images is generally assessed by practical experience, i.e. using rules of thumb, although some aspects and cases have been treated rigorously. In this paper we present a mathematical framework capable of describing the fundamental limits of radio astronomical imaging problems. Although the data model assumes a single snapshot observation, i.e. variations in time and frequency are not considered, this framework is sufficiently general to allow extension to synthesis observations. Using tools from statistical signal processing and linear algebra, we discuss the tractability of the imaging and deconvolution problem, the redistribution of noise in the map by the imaging and deconvolution process, the covariance of the image values due to propagation of calibration errors and thermal noise and the upper limit on the number of sources tractable by self calibration. The combination of covariance of the image values and the number of tractable sources determines the effective noise ...
Fundamental Limits of Ultrathin Metasurfaces
Arbabi, Amir
2014-01-01
We present universal theoretical limits on the operation and performance of non-magnetic passive ultrathin metasurfaces. In particular, we prove that their local transmission, reflection, and polarization conversion coefficients are confined to limited regions of the complex plane. As a result, full control over the phase of the light transmitted through such metasurfaces cannot be achieved if the polarization of the light is not to be affected at the same time. We also establish fundamental limits on the maximum polarization conversion efficiency of these metasurfaces, and show that they cannot achieve more than 25% polarization conversion efficiency in transmission.
Fundamental thermal noise in droplet microresonators
Giorgini, Antonio; Malara, Pietro; De Natale, Paolo; Gagliardi, Gianluca
2016-01-01
Liquid droplet whispering-gallery-mode microresonators open a new research frontier for optomechanics and photonic devices. At visible wavelengths, where most liquids are transparent, a major contribution to a droplet optical quality factor is expected theoretically from thermal surface distortions and capillary waves. Here, we investigate experimentally these predictions using transient cavity ring-down spectroscopy. In this way, the optical out-coupling and intrinsic loss are measured independently while any perturbation induced by thermal, acoustic and laser-frequency noise is avoided thanks to the ultra-short light-cavity interaction time. The measurements reveal a photon lifetime ten times longer than the thermal limit and suggest that capillary fluctuations activate surface scattering effects responsible for light coupling.
Vyshnevyy, Andrey A.; Fedyanin, Dmitry Yu.
2016-12-01
Incorporation of gain media in plasmonic nanostructures can give the possibility to compensate for high Ohmic losses in the metal and design truly nanoscale optical components for diverse applications ranging from biosensing to on-chip data communication. However, the process of stimulated emission in the gain medium is inevitably accompanied by spontaneous emission. This spontaneous emission greatly impacts the performance characteristics of deep-subwavelength active plasmonic devices and casts doubt on their practical use. Here we develop a theoretical framework to evaluate the influence of spontaneous emission, which can be applied to waveguide structures of any shape and level of mode confinement. In contrast to the previously developed theories, we take into account that the spectrum of spontaneous emission can be very broad and nonuniform, which is typical for deep-subwavelength structures, where a high optical gain (approximately 1000 cm-1 ) in the active medium is required to compensate for strong absorption in the metal. We also present a detailed study of the spontaneous emission noise in metal-semiconductor active plasmonic nanowaveguides and demonstrate that by using both optical and electrical filtering techniques, it is possible to decrease the noise to a level sufficient for practical applications at telecom and midinfrared wavelengths.
On noise limited cellular networks
Decreusefond, Laurent; Vu, Thanh-Tung
2010-01-01
This paper introduces a general theoretical framework to analyze noise limited networks. More precisely, we consider two homogenous Poisson point processes of base stations and users. General model of radio signal propagation and effect of fading are also considered. The main difference of our model with respect to other existing models is that a user connects to his best servers but not necessarily the closest one. We provide general formula for the outage probability. We study functionals related to the SNR as well as the sum of these functionals over all users per cell. For the latter, the expectation and bounds on the variance are obtained.
Fundamental gravitational limitations to quantum computing
Gambini, R; Pullin, J; Gambini, Rodolfo; Porto, Rafael A.; Pullin, Jorge
2005-01-01
Lloyd has considered the ultimate limitations physics places on quantum computers. He concludes in particular that for an ``ultimate laptop'' (a computer of one liter of volume and one kilogram of mass) the maximum number of operations per second is bounded by $10^{51}$. The limit is derived considering ordinary quantum mechanics. Here we consider additional limits that are placed by quantum gravity ideas, namely the use of a relational notion of time and fundamental gravitational limits that exist on time measurements. We then particularize for the case of an ultimate laptop and show that the maximum number of operations is further constrained to $10^{47}$ per second.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Noise limits. 36.103 Section 36.103... Noise limits. (a) For subsonic transport category large airplanes and subsonic jet airplanes compliance... greater than the Stage 3 noise limit prescribed in section B36.5(c) of appendix B of this part. (c)...
Fundamental limitations in filtering and control
Seron, Maria M
1997-01-01
The issue of fundamental limitations in filtering and control lies at the very heart of any feedback system design, since it reveals what is and is not achievable on the basis of that system's structural and dynamic characteristics. Alongside new succinct treatments of Bode's original results from the 1940s, this book presents a comprehensive analysis of modern results, featuring contemporary developments in multivariable systems, sampled-data, periodic and nonlinear problems. The text gives particular prominence to sensitivity functions which measure the fundamental qualities of the system, including performance and robustness. With extensive appendices covering the necessary background on complex variable theory, this book is an ideal self-contained resource for researchers and practitioners in this field.
Observation of Fundamental Thermal Noise in Optical Fibers down to Infrasonic Frequencies
Dong, Jing; Li, Tang; Liu, Liang
2015-01-01
The intrinsic thermal noise in optical fibers is the ultimate limit of fiber-based systems. However, at infrasonic frequencies, the spectral behavior of the intrinsic thermal noise remains unclear so far. We present the measurements of the fundamental thermal noise in optical fibers obtained using a balanced fiber Michelson interferometer. When an ultra-stable laser is used as the laser source and other noise sources are carefully controlled, the 1/f spectral density of thermal noise is observed down to infrasonic frequencies and the measured magnitude is consistent with the theoretical predictions at the frequencies from 0.2 Hz to 20 kHz. Moreover, as observed in the experiment, the level of 1/f thermal noise is reduced by changing the coating of optical fibers. Therefore, a possible way to reduce the thermal noise in optical fibers at low Fourier frequencies is indicated. Finally, the inconsistency between the experimental data on thermomechanical noise and existing theory is discussed.
Fundamental limits of repeaterless quantum communications.
Pirandola, Stefano; Laurenza, Riccardo; Ottaviani, Carlo; Banchi, Leonardo
2017-04-26
Quantum communications promises reliable transmission of quantum information, efficient distribution of entanglement and generation of completely secure keys. For all these tasks, we need to determine the optimal point-to-point rates that are achievable by two remote parties at the ends of a quantum channel, without restrictions on their local operations and classical communication, which can be unlimited and two-way. These two-way assisted capacities represent the ultimate rates that are reachable without quantum repeaters. Here, by constructing an upper bound based on the relative entropy of entanglement and devising a dimension-independent technique dubbed 'teleportation stretching', we establish these capacities for many fundamental channels, namely bosonic lossy channels, quantum-limited amplifiers, dephasing and erasure channels in arbitrary dimension. In particular, we exactly determine the fundamental rate-loss tradeoff affecting any protocol of quantum key distribution. Our findings set the limits of point-to-point quantum communications and provide precise and general benchmarks for quantum repeaters.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Noise limits. 36.501 Section 36.501..., Commuter Category Airplanes § 36.501 Noise limits. (a) Compliance with this subpart must be shown for— (1... applicable limit set in Part D of appendix F. (c) For aircraft covered by this subpart for...
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Noise limits. 36.805 Section 36.805...: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION Helicopters § 36.805 Noise limits. (a) Compliance with the... levels of the helicopter are no greater than the applicable limits prescribed under section H36.305...
Surpassing Fundamental Limits of Oscillators Using Nonlinear Resonators
Villanueva, L. G.; Kenig, E.; Karabalin, R. B.; Matheny, M. H.; Lifshitz, Ron; Cross, M. C.; Roukes, M. L.
2013-01-01
In its most basic form an oscillator consists of a resonator driven on resonance, through feedback, to create a periodic signal sustained by a static energy source. The generation of a stable frequency, the basic function of oscillators, is typically achieved by increasing the amplitude of motion of the resonator while remaining within its linear, harmonic regime. Contrary to this conventional paradigm, in this Letter we show that by operating the oscillator at special points in the resonator’s anharmonic regime we can overcome fundamental limitations of oscillator performance due to thermodynamic noise as well as practical limitations due to noise from the sustaining circuit. We develop a comprehensive model that accounts for the major contributions to the phase noise of the nonlinear oscillator. Using a nano-electromechanical system based oscillator, we experimentally verify the existence of a special region in the operational parameter space that enables suppressing the most significant contributions to the oscillator’s phase noise, as predicted by our model. PMID:23679770
Quantum limited heterodyne detection of spin noise
Cronenberger, S.; Scalbert, D.
2016-09-01
Spin noise spectroscopy is a powerful technique for studying spin relaxation in semiconductors. In this article, we propose an extension of this technique based on optical heterodyne detection of spin noise, which provides several key advantages compared to conventional spin noise spectroscopy: detection of high frequency spin noise not limited by detector bandwidth or sampling rates of digitizers, quantum limited sensitivity even in case of very weak probe power, and possible amplification of the spin noise signal. Heterodyne detection of spin noise is demonstrated on insulating n-doped GaAs. From measurements of spin noise spectra up to 0.4 Tesla, we determined the distribution of g-factors, Δg/g = 0.49%.
Sensitivity, quantum limits, and quantum enhancement of noise spectroscopies
Lucivero, Vito Giovanni; Kong, Jia; Jiménez-Martínez, Ricardo; Mitchell, Morgan W
2016-01-01
We study the fundamental limits of noise spectroscopy using estimation theory, Faraday rotation probing of an atomic spin system, and squeezed light. We find a simple and general expression for the Fisher information, which quantifies the sensitivity to spectral parameters such as resonance frequency and linewidth. For optically-detected spin noise spectroscopy, we find that shot noise imposes "local" standard quantum limits for any given probe power and atom number, and also "global" standard quantum limits when probe power and atom number are taken as free parameters. We confirm these estimation theory results using non-destructive Faraday rotation probing of hot Rb vapor, observing the predicted optima and finding good quantitative agreement with a first-principles calculation of the spin noise spectra. Finally, we show sensitivity beyond the atom- and photon-number-optimized global standard quantum limit using squeezed light.
The Low Noise Limit in Gene Expression.
Directory of Open Access Journals (Sweden)
Roy D Dar
Full Text Available Protein noise measurements are increasingly used to elucidate biophysical parameters. Unfortunately noise analyses are often at odds with directly measured parameters. Here we show that these inconsistencies arise from two problematic analytical choices: (i the assumption that protein translation rate is invariant for different proteins of different abundances, which has inadvertently led to (ii the assumption that a large constitutive extrinsic noise sets the low noise limit in gene expression. While growing evidence suggests that transcriptional bursting may set the low noise limit, variability in translational bursting has been largely ignored. We show that genome-wide systematic variation in translational efficiency can-and in the case of E. coli does-control the low noise limit in gene expression. Therefore constitutive extrinsic noise is small and only plays a role in the absence of a systematic variation in translational efficiency. These results show the existence of two distinct expression noise patterns: (1 a global noise floor uniformly imposed on all genes by expression bursting; and (2 high noise distributed to only a select group of genes.
Limits of noise squeezing in Kerr effect
Bajer, J; Tanas, R
2002-01-01
It is well known that the optical Kerr effect can be a source of highly squeezed light, however the analytical limit of the noise suppression has not been found yet. The process is reconsidered and an analytical estimation of the optimal quadrature noise level is presented. The validity of the new scaling law is checked numerically and analytically.
Fundamental limits of target detection performance in passive polarization imaging.
Goudail, François; Boffety, Matthieu
2017-04-01
We quantitatively determine the target detection performance of different passive polarization imaging architectures perturbed by signal-independent detection noise or signal-dependent Poisson shot noise. We compare the fully adaptive polarimetric imager and the best channel of a static polarimetric imager, and in each case, we compare the use of a polarizer and a polarizing beam splitter as the polarization analyzing device. For all these configurations, we derive a closed-form expression of the target/background separability and quantify the performance gain brought by polarization imaging compared to standard intensity imaging. We show in particular that all the considered polarimetric imaging configurations but one require a minimum value of the polarimetric contrast in order to outperform intensity imaging. The only configuration that always performs better than intensity imaging uses a polarizing beam splitter in the presence of background shot noise. These results are useful in evaluating the fundamental limits of the gain brought by polarization imaging and determining, in practice, which type of imaging architecture is preferable for a given application.
Fundamental Limits of Scintillation Detector Timing Precision
Derenzo, Stephen E.; Choong, Woon-Seng; Moses, William W.
2014-01-01
In this paper we review the primary factors that affect the timing precision of a scintillation detector. Monte Carlo calculations were performed to explore the dependence of the timing precision on the number of photoelectrons, the scintillator decay and rise times, the depth of interaction uncertainty, the time dispersion of the optical photons (modeled as an exponential decay), the photodetector rise time and transit time jitter, the leading-edge trigger level, and electronic noise. The Monte Carlo code was used to estimate the practical limits on the timing precision for an energy deposition of 511 keV in 3 mm × 3 mm × 30 mm Lu2SiO5:Ce and LaBr3:Ce crystals. The calculated timing precisions are consistent with the best experimental literature values. We then calculated the timing precision for 820 cases that sampled scintillator rise times from 0 to 1.0 ns, photon dispersion times from 0 to 0.2 ns, photodetector time jitters from 0 to 0.5 ns fwhm, and A from 10 to 10,000 photoelectrons per ns decay time. Since the timing precision R was found to depend on A−1/2 more than any other factor, we tabulated the parameter B, where R = BA−1/2. An empirical analytical formula was found that fit the tabulated values of B with an rms deviation of 2.2% of the value of B. The theoretical lower bound of the timing precision was calculated for the example of 0.5 ns rise time, 0.1 ns photon dispersion, and 0.2 ns fwhm photodetector time jitter. The lower bound was at most 15% lower than leading-edge timing discrimination for A from 10 to 10,000 photoelectrons/ns. A timing precision of 8 ps fwhm should be possible for an energy deposition of 511 keV using currently available photodetectors if a theoretically possible scintillator were developed that could produce 10,000 photoelectrons/ns. PMID:24874216
Zero noise limits using local times
2013-01-01
We consider a well-known family of SDEs with irregular drifts and the correspondent zero noise limits. Using (mollified) local times, we show which trajectories are selected. The approach is completely probabilistic and relies on elementary stochastic calculus only.
33 CFR 86.03 - Limits of fundamental frequencies.
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Limits of fundamental frequencies... of fundamental frequencies. To ensure a wide variety of whistle characteristics, the fundamental frequency of a whistle shall be between the following limits: (a) 70-200 Hz, for a vessel 200 meters or...
On the Fundamental Limits of Adaptive Sensing
Arias-Castro, Ery; Davenport, Mark
2011-01-01
Suppose we can sequentially acquire arbitrary linear measurements of an n-dimensional vector x resulting in the linear model y = Ax + z, where z represents measurement noise. If the signal is known to be sparse, one would expect the following folk theorem to be true: choosing an adaptive strategy which cleverly selects the next row of A based on what has been previously observed should do far better than a nonadaptive strategy which sets the rows of A ahead of time, thus not trying to learn anything about the signal in between observations. This paper shows that the folk theorem is false. We prove that the advantages offered by clever adaptive strategies and sophisticated estimation procedures---no matter how intractable---over classical compressed acquisition/recovery schemes are, in general, minimal.
Fundamental limits of optical force and torque
Rahimzadegan, A.; Alaee, R.; Fernandez-Corbaton, I.; Rockstuhl, C.
2017-01-01
Optical force and torque provide unprecedented control on the spatial motion of small particles. A valid scientific question, that has many practical implications, concerns the existence of fundamental upper bounds for the achievable force and torque exerted by a plane wave illumination with a given intensity. Here, while studying isotropic particles, we show that different light-matter interaction channels contribute to the exerted force and torque, and analytically derive upper bounds for each of the contributions. Specific examples for particles that achieve those upper bounds are provided. We study how and to which extent different contributions can add up to result in the maximum optical force and torque. Our insights are important for applications ranging from molecular sorting, particle manipulation, and nanorobotics up to ambitious projects such as laser-propelled spaceships.
Fundamental Limits of Optical Force and Torque
Rahimzadegan, Aso; Fernandez-Corbaton, Ivan; Rockstuhl, Carsten
2016-01-01
Optical force and torque provide unprecedented control on the spatial motion of small particles. A valid scientific question, that has many practical implications, concerns the existence of fundamental upper bounds for the achievable force and torque exerted by a plane wave illumination with a given intensity. Here, while studying isotropic particles, we show that different light-matter interaction channels contribute to the exerted force and torque and analytically derive upper bounds for each of the contributions. Specific examples for particles that achieve those upper bounds are provided. We study how and to which extent different contributions can be made to add up. Our insights are important for applications ranging from molecular sorting, particle manipulation, nanorobotics up to ambitious projects such as laser-propelled spaceships.
Fundamental energetic limits of radio communication systems
Baudais, Jean-Yves
2017-02-01
The evaluation of the energy consumption of a radiocommunication requires to analyse the life cycle of the elements used. However, this analysis does not specify the energetic limits. Theoretical approaches allow one to draw these limits, which are known in multiple cases of information transmission. However, the answers are not always satisfactory, in particular in the case of time-varying channels. After a brief presentation of the notion of energetic limits of a radiocommunication, and beginning with a global approach, we show that, contrary to the published results, the energetic limits always differ from zero if the physical constraints are correctly expressed. xml:lang="fr" Cependant, les réponses ne sont pas toujours satisfaisantes, particulièrement dans le cas de canaux variants dans le temps. Après une rapide présentation des notions d'énergie limite d'une radiocommunication, et en commençant par une approche globale du problème, nous montrons que, contrairement aux résultats publiés, les limites énergétiques sont toujours différentes de zéro si les contraintes physiques sont correctement exprimées.
Thermal-noise-limited underground interferometer CLIO
Agatsuma, Kazuhiro; Fujimoto, Masa-Katsu; Kawamura, Seiji; Kuroda, Kazuaki; Miyakawa, Osamu; Miyoki, Shinji; Ohashi, Masatake; Suzuki, Toshikazu; Takahashi, Ryutaro; Tatsumi, Daisuke; Telada, Souichi; Uchiyama, Takashi; Yamamoto, Kazuhiro
2009-01-01
We report on the current status of CLIO (Cryogenic Laser Interferometer Observatory), which is a prototype interferometer for LCGT (Large scale Cryogenic Gravitational-wave Telescope). LCGT is a Japanese next-generation interferometric gravitational wave detector featuring the use of cryogenic mirrors and a quiet underground site. The main purpose of CLIO is to demonstrate a reduction of the mirror thermal noise by cooling the sapphire mirrors. CLIO is located in an underground site of the Kamioka mine, 1000 m deep from the mountain top, to verify its advantages. After a few years of commissioning work, we have achieved a thermal-noise-limited sensitivity at room temperature. One of the main results of noise hunting was the elimination of thermal noise caused by a conductive coil-holder coupled with a pendulum through magnets.
Fundamental limits of positron emission mammography
Energy Technology Data Exchange (ETDEWEB)
Moses, William W.; Qi, Jinyi
2001-06-01
We explore the causes of performance limitation in positron emission mammography cameras. We compare two basic camera geometries containing the same volume of 511 keV photon detectors, one with a parallel plane geometry and another with a rectangular geometry. We find that both geometries have similar performance for the phantom imaged (in Monte Carlo simulation), even though the solid angle coverage of the rectangular camera is about 50 percent higher than the parallel plane camera. The reconstruction algorithm used significantly affects the resulting image; iterative methods significantly outperform the commonly used focal plane tomography. Finally, the characteristics of the tumor itself, specifically the absolute amount of radiotracer taken up by the tumor, will significantly affect the imaging performance.
Mathematical Fundamentals for the Noise Immunity of the Genetic Code.
Fimmel, Elena; Strüngmann, Lutz
2017-09-13
Symmetry is one of the essential and most visible patterns that can be seen in nature. Starting from the left-right symmetry of the human body, all types of symmetry can be found in crystals, plants, animals and nature as a whole. Similarly, principals of symmetry are also some of the fundamental and most useful tools in modern mathematical natural science that play a major role in theory and applications. As a consequence, it is not surprising that the desire to understand the origin of life, based on the genetic code, forces us to involve symmetry as a mathematical concept. The genetic code can be seen as a key to biological self-organisation. All living organisms have the same molecular bases - an alphabet consisting of four letters (nitrogenous bases): adenine, cytosine, guanine, and thymine. Linearly ordered sequences of these bases contain the genetic information for synthesis of proteins in all forms of life. Thus, one of the most fascinating riddles of nature is to explain why the genetic code is as it is. Genetic coding possesses noise immunity which is the fundamental feature that allows to pass on the genetic information from parents to their descendants. Hence, since the time of the discovery of the genetic code, scientists have tried to explain the noise immunity of the genetic information. In this chapter we will discuss recent results in mathematical modelling of the genetic code with respect to noise immunity, in particular error-detection and error-correction. We will focus on two central properties: Degeneracy and frameshift correction. Different amino acids are encoded by different quantities of codons and a connection between this degeneracy and the noise immunity of genetic information is a long standing hypothesis. Biological implications of the degeneracy have been intensively studied and whether the natural code is a frozen accident or a highly optimised product of evolution is still controversially discussed. Symmetries in the structure of
Noise in state of the art clocks and their impact for fundamental physics
Maleki, L.
2001-01-01
In this paper a review of the use of advanced atomic clocks in testing the fundamental physical laws will be presented. Noise sources of clocks will be discussed, together with an outline their characterization based on current models. The paper will conclude with a discussion of recent attempts to reduce the fundamental, as well as technical noise in atomic clocks.
Predetermining acceptable noise limits in EXAFS spectra in the limit of stochastic noise
Energy Technology Data Exchange (ETDEWEB)
Hu, Yung-Jin; Booth, Corwin H
2009-12-14
EXAFS measurements are used to probe a variety of experimental systems, but excel at elucidating local structure in samples which have slight disorder or no long-range crystalline order. Of special interest to the authors is the use of EXAFS in understanding the molecular-level binding structure and characteristics of actinides on the surface of environmental minerals and model mineral analogs. In environmental systems the element of interest can be on the order of 10-7% by weight of the total sample. Obviously such samples would be impossible to measure using EXAFS techniques. It is therefore essential to increase the concentration of the element of interest while still preserving a sample's ability to represent environmental conditions. Under such low concentration limits it is expected that the collected data is countrate, or stochastically limited. This condition occurs as we approach the signal-to-noise (S/N) limit of the technique where the random noise of the measurement process dominates over possible systematic errors. When stochastic error is expected to dominate systematic error, it is possible to predict, with the use of simulations, the ability of model fits to tolerate a certain level of stochastic noise. Elsewhere in these proceedings, we discuss how to tell when systematic errors dominate in measured EXAFS spectrum. Here, we outline a technique for determining the number of EXAFS scans necessary to test the relevance of a given structural model. Appropriate stochastic noise levels are determined for each point in r-space by collecting data on a real system. These noise levels are then applied to EXAFS simulations using a test model. In this way, all significant systematic error sources are eliminated in the simulated data. The structural model is then fit to the simulated data, decreasing the noise and increasing the k-range of the fit until the veracity of the model passes an F-test. This paper outlines a method of testing model systems in
Fundamental limit of light trapping in grating structures
Yu, Zongfu
2010-08-11
We use a rigorous electromagnetic approach to analyze the fundamental limit of light-trapping enhancement in grating structures. This limit can exceed the bulk limit of 4n 2, but has significant angular dependency. We explicitly show that 2D gratings provide more enhancement than 1D gratings. We also show the effects of the grating profile’s symmetry on the absorption enhancement limit. Numerical simulations are applied to support the theory. Our findings provide general guidance for the design of grating structures for light-trapping solar cells.
Fundamental size limitations of micro four-point probes
DEFF Research Database (Denmark)
Ansbæk, Thor; Petersen, Dirch Hjorth; Hansen, Ole
2009-01-01
-scaled as well in order to correctly characterize the extremely thin films used. This presents a four-point probe design and fabrication challenge. We analyze the fundamental limitation on down-scaling of a generic micro four-point probe (M4PP) in a comprehensive study, where mechanical, thermal, and electrical...
Fundamental Speed Limits to the Generation of Quantumness
Jing, Jun; Wu, Lian-Ao; Del Campo, Adolfo
2016-11-01
Quantum physics dictates fundamental speed limits during time evolution. We present a quantum speed limit governing the generation of nonclassicality and the mutual incompatibility of two states connected by time evolution. This result is used to characterize the timescale required to generate a given amount of quantumness under an arbitrary physical process. The bound is found to be tight under pure dephasing dynamics. More generally, our analysis reveals the dependence on the initial and final states and non-Markovian effects.
Some Fundamental Limits on SAW RFID Tag Information Capacity and Collision Resolution
Barton, Richard J.
2013-01-01
In this paper, we apply results from multi-user information theory to study the limits of information capacity and collision resolution for SAW RFID tags. In particular, we derive bounds on the achievable data rate per tag as a function of fundamental parameters such as tag time-bandwidth product, tag signal-to-noise ratio (SNR), and number of tags in the environment. We also discuss the implications of these bounds for tag waveform design and tag interrogation efficiency
The ODELIA Study on Noise Limits for Outdoor Machinery
Dittrich, M.G.; Carletti, E.; Spellerberg, G.
2016-01-01
In the ODELIA study for the European Commission an assessment of the outdoor equipment noise directive 2000/14/EC and its amendment 2005/88/EC has been performed. The directive requires noise marking for 57 types of equipment used outdoors, and sets noise limits for 22 of these. Since the limits
Fundamental Limits of Wideband Localization - Part II: Cooperative Networks
Shen, Yuan; Win, Moe Z
2010-01-01
The availability of positional information is of great importance in many commercial, governmental, and military applications. Localization is commonly accomplished through the use of radio communication between mobile devices (agents) and fixed infrastructure (anchors). However, precise determination of agent positions is a challenging task, especially in harsh environments due to radio blockage or limited anchor deployment. In these situations, cooperation among agents can significantly improve localization accuracy and reduce localization outage probabilities. A general framework of analyzing the fundamental limits of wideband localization has been developed in Part I of the paper. Here, we build on this framework and establish the fundamental limits of wideband cooperative location-aware networks. Our analysis is based on the waveforms received at the nodes, in conjunction with Fisher information inequality. We provide a geometrical interpretation of equivalent Fisher information for cooperative networks....
2016-08-24
decades, however methods of measurably controlling -reducing jet noise in an efficient and robust manner remain evasive. Previous research has shown...2016 1-May-2013 30-Apr-2016 High Temperature Supersonic Jet Noise - Fundamental Studies and Control using Advanced Actuation Methods The views...and Control using Advanced Actuation Methods Report Title Understanding and controlling jet noise has been the focus of analytical, computational and
Noise limitations in optical linear algebra processors.
Batsell, S G; Jong, T L; Walkup, J F; Krile, T F
1990-05-10
A general statistical noise model is presented for optical linear algebra processors. A statistical analysis which includes device noise, the multiplication process, and the addition operation is undertaken. We focus on those processes which are architecturally independent. Finally, experimental results which verify the analytical predictions are also presented.
Fundamental Limits of Data Analytics in Sociotechnical Systems
Directory of Open Access Journals (Sweden)
Lav R. Varshney
2016-02-01
Full Text Available In the Big Data era, informational systems involving humans and machines are being deployed in multifarious societal settings. Many use data analytics as subcomponents for descriptive, predictive, and prescriptive tasks, often trained using machine learning. Yet when analytics components are placed in large-scale sociotechnical systems, it is often difficult to characterize how well the systems will act, measured with criteria relevant in the world. Here, we propose a system modeling technique that treats data analytics components as `noisy black boxes' or stochastic kernels, which together with elementary stochastic analysis provides insight into fundamental performance limits.An example application is helping prioritize people's limited attention, where learning algorithms rank tasks using noisy features and people sequentially select from the ranked list. This paper demonstrates the general technique by developing a stochastic model of analytics-enabled sequential selection, derives fundamental limits using concomitants of order statistics, and assesses limits in terms of system-wide performance metrics like screening cost and value of objects selected. Connections to sample complexity for bipartite ranking are also made.
Investigation of fundamental limits to beam brightness available from photoinjectors
Energy Technology Data Exchange (ETDEWEB)
Bazarov, Ivan [Cornell Univ., Ithaca, NY (United States)
2015-07-09
The goal of this project was investigation of fundamental limits to beam brightness available from photoinjectors. This basic research in accelerator physics spanned over 5 years aiming to extend the fundamental understanding of high average current, low emittance sources of relativistic electrons based on photoemission guns, a necessary prerequisite for a new generation of coherent X-ray synchrotron radiation facilities based on continuous duty superconducting linacs. The program focused on two areas critical to making advances in the electron source performance: 1) the physics of photocathodes for the production of low emittance electrons and 2) control of space charge forces in the immediate vicinity to the cathode via 3D laser pulse shaping.
The fundamental downscaling limit of field effect transistors
Energy Technology Data Exchange (ETDEWEB)
Mamaluy, Denis, E-mail: mamaluy@sandia.gov; Gao, Xujiao [Sandia National Laboratories, Albuquerque, New Mexico 87185-1322 (United States)
2015-05-11
We predict that within next 15 years a fundamental down-scaling limit for CMOS technology and other Field-Effect Transistors (FETs) will be reached. Specifically, we show that at room temperatures all FETs, irrespective of their channel material, will start experiencing unacceptable level of thermally induced errors around 5-nm gate lengths. These findings were confirmed by performing quantum mechanical transport simulations for a variety of 6-, 5-, and 4-nm gate length Si devices, optimized to satisfy high-performance logic specifications by ITRS. Different channel materials and wafer/channel orientations have also been studied; it is found that altering channel-source-drain materials achieves only insignificant increase in switching energy, which overall cannot sufficiently delay the approaching downscaling limit. Alternative possibilities are discussed to continue the increase of logic element densities for room temperature operation below the said limit.
Fundamental Limits in Combine Harvester Header Height Control.
Xie, Yangmin; Alleyne, Andrew G; Greer, Ashley; Deneault, Dustin
2013-05-01
This paper investigates fundamental performance limitations in the control of a combine harvester's header height control system. There are two primary subsystem characteristics that influence the achievable bandwidth by affecting the open loop transfer function. The first subsystem is the mechanical configuration of the combine and header while the second subsystem is the electrohydraulic actuation for the header. The mechanical combine + header subsystem results in an input-output representation that is underactuated and has a noncollocated sensor/actuator pair. The electrohydraulic subsystem introduces a significant time delay. In combination, they each reinforce the effect of the other thereby exacerbating the overall system limitation of the closed loop bandwidth. Experimental results are provided to validate the model and existence of the closed loop bandwidth limitations that stem from specific system design configurations.
Spatiotemporal noise covariance estimation from limited empirical magnetoencephalographic data
Energy Technology Data Exchange (ETDEWEB)
Jun, Sung C [MS-D454, Applied Modern Physics Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Plis, Sergey M [MS-D454, Applied Modern Physics Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Ranken, Doug M [MS-D454, Applied Modern Physics Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Schmidt, David M [MS-D454, Applied Modern Physics Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2006-11-07
The performance of parametric magnetoencephalography (MEG) and electroencephalography (EEG) source localization approaches can be degraded by the use of poor background noise covariance estimates. In general, estimation of the noise covariance for spatiotemporal analysis is difficult mainly due to the limited noise information available. Furthermore, its estimation requires a large amount of storage and a one-time but very large (and sometimes intractable) calculation or its inverse. To overcome these difficulties, noise covariance models consisting of one pair or a sum of multi-pairs of Kronecker products of spatial covariance and temporal covariance have been proposed. However, these approaches cannot be applied when the noise information is very limited, i.e., the amount of noise information is less than the degrees of freedom of the noise covariance models. A common example of this is when only averaged noise data are available for a limited prestimulus region (typically at most a few hundred milliseconds duration). For such cases, a diagonal spatiotemporal noise covariance model consisting of sensor variances with no spatial or temporal correlation has been the common choice for spatiotemporal analysis. In this work, we propose a different noise covariance model which consists of diagonal spatial noise covariance and Toeplitz temporal noise covariance. It can easily be estimated from limited noise information, and no time-consuming optimization and data-processing are required. Thus, it can be used as an alternative choice when one-pair or multi-pair noise covariance models cannot be estimated due to lack of noise information. To verify its capability we used Bayesian inference dipole analysis and a number of simulated and empirical datasets. We compared this covariance model with other existing covariance models such as conventional diagonal covariance, one-pair and multi-pair noise covariance models, when noise information is sufficient to estimate them. We
Energy Technology Data Exchange (ETDEWEB)
Sugiyama, T.; Naganawa, A. (Chubu Electric Power Co. Inc., Nagoya (Japan))
1994-05-01
Fundamental experiments were conducted on active noise control as sound insulation fence. This control method generates a sound source with the same amplitude and opposite phase as noise, and reduces noise through the interference of acoustic wave from the source. However, this method has too many problems with the three-dimensional sound field to be actually exploited in this environment. The following experiments were conducted to apply the active noise control to the sound insulation fence: one method of installing a geometric path along the inner side of the sound insulation fence used the acoustic delay process generated on the source side to attenuate the sound pressure level on top of the fence through interference of routing difference sound. The other method used an additional sound source attached to the bottom of the geometric path above to obtain a higher attenuation than using the simple sound insulation fence. At the second step, the active control duct model was used for the test. Then, the three-dimensional model test was conducted for active control of the sound insulation fence. The results of these fundamental experiments have indicated that each method can reduce the relative sound pressure level and the active noise control system using the acoustic phase difference can effectively reduce noise with dominant components in a low frequency band. There are still several problems with the three-dimensional mock-up model. 4 refs., 18 figs., 2 tabs.
Fundamental limitations in the purifications of tensor networks
Energy Technology Data Exchange (ETDEWEB)
De las Cuevas, G.; Cirac, J. I. [Max Planck Institute for Quantum Optics, Hans-Kopfermann-Str. 1, 85748 Garching (Germany); Cubitt, T. S. [Department of Computer Science, University College London, London WC1E 6BT, United Kingdom and DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Wolf, M. M. [Zentrum Mathematik, Technische Universität München, 85748 Garching (Germany); Pérez-García, D. [Departamento de Análisis Matemático and IMI, Universidad Complutense de Madrid, 28040 Madrid, Spain and ICMAT, C/ Nicolás Cabrera, Campus de Cantoblanco, 28049 Madrid (Spain)
2016-07-15
We show a fundamental limitation in the description of quantum many-body mixed states with tensor networks in purification form. Namely, we show that there exist mixed states which can be represented as a translationally invariant (TI) matrix product density operator valid for all system sizes, but for which there does not exist a TI purification valid for all system sizes. The proof is based on an undecidable problem and on the uniqueness of canonical forms of matrix product states. The result also holds for classical states.
Fundamental limitations in the purifications of tensor networks
De las Cuevas, G.; Cubitt, T. S.; Cirac, J. I.; Wolf, M. M.; Pérez-García, D.
2016-07-01
We show a fundamental limitation in the description of quantum many-body mixed states with tensor networks in purification form. Namely, we show that there exist mixed states which can be represented as a translationally invariant (TI) matrix product density operator valid for all system sizes, but for which there does not exist a TI purification valid for all system sizes. The proof is based on an undecidable problem and on the uniqueness of canonical forms of matrix product states. The result also holds for classical states.
Weak value amplification in a shot-noise limited interferometer
Nishizawa, Atsushi; Fujimoto, Masa-Katsu
2012-01-01
We study the weak-value amplification (WVA) in a phase measurement with an optical interferometer in which shot noise limits the sensitivity. We compute the signal and the shot noise including the full-order interaction terms of the WVA, and show that the shot-noise contribution to a phase shift in a pointer variable is always larger than the final variance of the pointer variable. To clarify an advantage for practical uses of the WVA, we discuss signal-to-noise ratio and its optimization in the presence of the shot noise.
Bound on range precision for shot-noise limited ladar systems.
Johnson, Steven; Cain, Stephen
2008-10-01
The precision of ladar range measurements is limited by noise. The fundamental source of noise in a laser signal is the random time between photon arrivals. This phenomenon, called shot noise, is modeled as a Poisson random process. Other noise sources in the system are also modeled as Poisson processes. Under the Poisson-noise assumption, the Cramer-Rao lower bound (CRLB) on range measurements is derived. This bound on the variance of any unbiased range estimate is greater than the CRLB derived by assuming Gaussian noise of equal variance. Finally, it is shown that, for a ladar capable of dividing a fixed amount of energy into multiple laser pulses, the range precision is maximized when all energy is transmitted in a single pulse.
Fundamental limitations in antenna resolution by maximum entropy methods
Energy Technology Data Exchange (ETDEWEB)
Bevensee, R.M.
1984-08-01
This paper summarizes work done during the past few years on antenna super-resolution of distant radiating sources, both incoherent with and without additive noise and coherent with and without additive noise.
Fundamental Limitations to Plasmonic Hot-Carrier Solar Cells.
Zhang, Yu; Yam, ChiYung; Schatz, George C
2016-05-19
Detailed balance between photon-absorption and energy loss constrains the efficiency of conventional solar cells to the Shockley-Queisser limit. However, if solar illumination can be absorbed over a wide spectrum by plasmonic structures, and the generated hot-carriers can be collected before relaxation, the efficiency of solar cells may be greatly improved. In this work, we explore the opportunities and limitations for making plasmonic solar cells, here considering a design for hot-carrier solar cells in which a conventional semiconductor heterojunction is attached to a plasmonic medium such as arrays of gold nanoparticles. The underlying mechanisms and fundamental limitations of this cell are studied using a nonequilibrium Green's function method, and the numerical results indicate that this cell can significantly improve the absorption of solar radiation without reducing open-circuit voltage, as photons can be absorbed to produce mobile carriers in the semiconductor as long as they have energy larger than the Schottky barrier rather than above the bandgap. However, a significant fraction of the hot-carriers have energies below the Schottky barrier, which makes the cell suffer low internal quantum efficiency. Moreover, quantum efficiency is also limited by hot-carrier relaxation and metal-semiconductor coupling. The connection of these results to recent experiments is described, showing why plasmonic solar cells can have less than 1% efficiency.
Lowitz, A E; Golwala, S R; Timbie, P T
2014-01-01
Kinetic inductance detectors (KIDs) show promise as a competitive technology for astronomical observations over a wide range of wavelengths. We are interested in comparing the fundamental limitations to the sensitivity of KIDs with that of transition edge sensors (TESs) at millimeter wavelengths, specifically over the wavelengths required for studies of the Cosmic Microwave Background (CMB). We calculate the total fundamental noise arising from optical and thermal excitations in TESs and KIDs for a variety of bath temperatures and optical loading scenarios for applications at millimeter wavelengths. Special consideration is given to the case of ground-based observations of 100 GHz radiation with a 100 mK bath temperature, conditions consistent with the planned second module of the QUBIC telescope, a CMB instrument. Under these conditions, a titanium nitride KID with optimized critical temperature pays a few percent noise penalty compared to a typical optimized TES.
Synchronization of Limit Cycle Oscillators by Telegraph Noise
Goldobin, Denis S.
2014-01-01
We study the influence of telegraph noise on synchrony of limit cycle oscillators. Adopting the phase description for these oscillators, we derive the explicit expression for the Lyapunov exponent. We show that either for weak noise or frequent switching the Lyapunov exponent is negative, and the phase model gives adequate analytical results. In some systems moderate noise can desynchronize oscillations, and we demonstrate this for the Van der Pol--Duffing system.
Fundamental Limits of Wideband Localization - Part I: A General Framework
Shen, Yuan
2010-01-01
The availability of positional information is of great importance in many commercial, public safety, and military applications. The coming years will see the emergence of location-aware networks with sub-meter accuracy, relying on accurate range measurements provided by wide bandwidth transmissions. In this two-part paper, we determine the fundamental limits of localization accuracy of wideband wireless networks in harsh multipath environments. We first develop a general framework to characterize the localization accuracy of a given node here and then extend our analysis to cooperative location-aware networks in Part II. In this paper, we characterize localization accuracy in terms of a performance measure called the squared position error bound (SPEB), and introduce the notion of equivalent Fisher information to derive the SPEB in a succinct expression. This methodology provides insights into the essence of the localization problem by unifying localization information from individual anchors and information ...
Challenging fundamental limits in the fabrication of vector vortex waveplates
Hakobyan, R. S.; Tabiryan, N. V.; Serabyn, E.
Vector vortex waveplates (VVWs) are in the heart of vortex coronagraphs aimed at exoplanet detection close to bright stars. VVWs made of liquid crystal polymers (LCPs) provide structural continuity, opportunity of high order singularities, large area, and inexpensive manufacturing technology. However, to date, the performance of such devices is compromised by imperfections in singularity area that allow some residual starlight leakage. Reducing the singularity to subwavelength sizes increases the energy of elastic deformations of the LC. As a result, the azimuthally symmetric orientation pattern gives way to 3D deformations that reduce the elastic energy of the LC. The stability of radial orientation is determined by elastic constants of the LC, the thickness of the layer and the boundary conditions. In the current paper, we examin the role of those factors to determine the fundamental limits the singularity area could be reduced to for LCP VVWs.
Fundamental limits for cooling of linear quantum refrigerators.
Freitas, Nahuel; Paz, Juan Pablo
2017-01-01
We study the asymptotic dynamics of arbitrary linear quantum open systems that are periodically driven while coupled with generic bosonic reservoirs. We obtain exact results for the heat flowing from each reservoir, and these results are valid beyond the weak-coupling or Markovian approximations. We prove the validity of the dynamical third law of thermodynamics (Nernst unattainability principle), showing that the ultimate limit for cooling is imposed by a fundamental heating mechanism that dominates at low temperatures, namely the nonresonant creation of excitation pairs in the reservoirs induced by the driving field. This quantum effect, which is missed in the weak-coupling approximation, restores the unattainability principle, the validity of which was recently challenged.
Shot-noise limited detection sensitivity in multiplex CARS microscopy
Müller, M.; Schins, J.M.; Wurpel, G.W.H.
2004-01-01
In multiplex CARS microscopy the generated anti-Stokes signal is generated and detected simultaneously over a significant part of the vibrational spectrum. The signal-to-noise ratio of the thus detected spectra is limited only by shot-noise. This principle is demonstrated using a dilution series of
Challenges and limitations in retrofitting facilities for low frequency noise
Energy Technology Data Exchange (ETDEWEB)
Wierzba, P. [ATCO Noise Management, Calgary, AB (Canada)
2007-07-01
The trend to revise and increase environmental regulations regarding low frequency noise emissions from oil and gas facilities was discussed. Noise related complaints can often be traced to low frequency noise, which is the unwanted sound with a frequency range falling within 31.5-Hz, 63-Hz, and 125-Hz octave bands. This paper also discussed the challenges and limitations of field retrofits of the facilities aimed at reducing low frequency noise. The main sources of low frequency noise associated with a compression facility are the radiator cooler, engine exhaust and the building envelope. Regulators are paying close attention not only to the overall noise exposure as measured by the A-weighted levels, but also to the quality of noise emitted by the particular frequency spectrum. The Alberta Energy and Utilities Board recently issued Noise Control Directive 38 and made it a requirement to perform low frequency noise impact assessment for permitting of all new energy facilities. Under Directive 38, the low frequency noise assessment is to be performed using the C-weighted scale as a measure in addition to the previously used A-weighted scale. Directive 38 recommends that in order to avoid low frequency noise problems the difference between the C-weighted and A-weighted levels at the residential locations should be lower than 20 dB. This implies that noise should be limited to 60 dBC for Category 1 residences of low dwelling density. Small upgrades and changes can be made to lower low frequency noise emissions. These may include upgrading building wall insulation, providing wall-to-skid isolation system, upgrading the fan blades, or reducing the rpm of the fans. It was concluded that these upgrades should be considered for facilities in close proximity to residential areas. 3 refs., 2 tabs., 7 figs.
Space and time in ecology: Noise or fundamental driver? [chapter 2
Samuel A. Cushman
2010-01-01
In this chapter I frame the central issue of the book, namely is spatial and temporal complexity in ecological systems merely noise around the predictions of non-spatial, equilibrium processes? Or, alternatively, do spatial and temporal variability in the environment and autogenic spaceÂtime processes in populations fundamentally alter system behavior such that ideal...
Cross-spectrum Measurement of Thermal-noise Limited Oscillators
Hati, Archita; Howe, David A
2015-01-01
Cross-spectrum analysis is a commonly-used technique for the detection of phase and amplitude noise of a signal in the presence of interfering noise. It extracts the desired correlated noise from two time series in the presence of uncorrelated interfering noise. Recently, we demonstrated that the phase-inversion (anti-correlation) effect due to AM noise leakage can cause complete or partial collapse of the cross-spectral function. In this paper, we discuss the newly discovered effect of anti-correlated thermal noise that originates from the common-mode power divider (splitter), an essential component in a cross-spectrum noise measurement system. We studied this effect for different power splitters and discuss its influence on the measurement of thermal-noise limited oscillators. An oscillator whose thermal noise is primarily set by the 50 ohm source resistance is referred to as a thermally-limited oscillator. We provide theory, simulation and experimental results. In addition, we expand this study to reveal h...
Statistical Angular Resolution Limit for Ultrawideband MIMO Noise Radar
2015-01-01
The two-dimensional angular resolution limit (ARL) of elevation and azimuth for MIMO radar with ultrawideband (UWB) noise waveforms is investigated using statistical resolution theory. First, the signal model of monostatic UWB MIMO noise radar is established in a 3D reference frame. Then, the statistical angular resolution limits (SARLs) of two closely spaced targets are derived using the detection-theoretic and estimation-theoretic approaches, respectively. The detection-theoretic approach i...
Laser noise imposed limitations of ensemble quantum metrology
Plankensteiner, D.; Schachenmayer, J.; Ritsch, H.; Genes, C.
2016-12-01
Laser noise is a decisive limiting factor in high precision spectroscopy of narrow lines using atomic ensembles. In an idealized Doppler and differential-light-shift-free magic wavelength lattice configuration, it remains as one distinct principal limitation beyond collective atomic decay. In this work we study the limitations originating from laser phase and amplitude noise in an idealized Ramsey pulse interrogation scheme with uncorrelated atoms. Phase noise leads to a saturation of the frequency sensitivity with increasing atom number while amplitude noise implies a scaling 1/\\sqrt{τ } with τ being the interrogation time. We employ a technique using decoherence-free subspaces first introduced in Dorner (2012 New J. Phys. 14 043011) which can restore the scaling with the square root of the inverse particle number 1/\\sqrt{N}. Similar results and improvements are obtained numerically for a Rabi spectroscopy setup.
Effects of speech noise on vocal fundamental frequency using power spectral analysis.
Lee, Guo-She; Hsiao, Tzu-Yu; Yang, Cheryl C H; Kuo, Terry B J
2007-06-01
To investigate the relationship between auditory function and vocal fundamental frequency (F0) using binaural masking with speech noise during sustained vowel vocalization. Eight healthy subjects were instructed to vocalize the sustained vowel /a/ at the intensities of 65 to 75 dBA and 90 to 100 dBA as steadily as possible. The phonations without noise masking were compared with the phonations under masking with 85-dBA speech noise presented to both ears through headphones. The F0s were obtained by using autocorrelation of the voice signals and were converted to cents to form a F0 sequence. The power spectrum of the F0 sequence was then acquired using fast Fourier transformation. A significant increase in the power spectrum in the frequency range of production by decreasing F0 modulation at production and auditory feedback.
Down to the fundamental lower limit of direct time cognition
Fanchenko, S. D.; Schelev, Mikhail Y.
1999-06-01
The age of high-speed photography exceeds a century and may be divided into three epochs: recording of fast events being illuminated with short light bursts; opto-mechanical recording with mechanical shutters, rotating drums, prisms and mirrors; and high-speed recording with the help of electron imaging tubes. During the third epoch the authors have been enthusiastically involved into pico-femtosecond image- converter physics and technology by establishing fundamental principles and experimental realization of ultrafast image- tube photography.
Speckle Decorrelation and Dynamic Range in Speckle Noise Limited Imaging
Sivaramakrishnan, A; Hodge, P E; MacIntosh, B A; Sivaramakrishnan, Anand; Lloyd, James P.; Hodge, Philip E.; Macintosh, Bruce A.
2002-01-01
The useful dynamic range of an image in the diffraction limited regime is usually limited by speckles caused by residual phase errors in the optical system forming the image. The technique of speckle decorrelation involves introducing many independent realizations of additional phase error into a wavefront during one speckle lifetime, changing the instantaneous speckle pattern. A commonly held assumption is that this results in the speckles being `moved around' at the rate at which the additional phase screens are applied. The intention of this exercise is to smooth the speckles out into a more uniform background distribution during their persistence time, thereby enabling companion detection around bright stars to be photon noise limited rather than speckle-limited. We demonstrate analytically why this does not occur, and confirm this result with numerical simulations. We show that the original speckles must persist, and that the technique of speckle decorrelation merely adds more noise to the original speck...
Determination of the Thermal Noise Limit of Graphene Biotransistors.
Crosser, Michael S; Brown, Morgan A; McEuen, Paul L; Minot, Ethan D
2015-08-12
To determine the thermal noise limit of graphene biotransistors, we have measured the complex impedance between the basal plane of single-layer graphene and an aqueous electrolyte. The impedance is dominated by an imaginary component but has a finite real component. Invoking the fluctuation-dissipation theorem, we determine the power spectral density of thermally driven voltage fluctuations at the graphene/electrolyte interface. The fluctuations have 1/f(p) dependence, with p = 0.75-0.85, and the magnitude of fluctuations scales inversely with area. Our results explain noise spectra previously measured in liquid-gated suspended graphene devices and provide realistic targets for future device performance.
Deterministic superresolution with coherent states at the shot noise limit
DEFF Research Database (Denmark)
Distante, Emanuele; Jezek, Miroslav; Andersen, Ulrik L.
2013-01-01
detection approaches. Here we show that superresolving phase measurements at the shot noise limit can be achieved without resorting to nonclassical optical states or to low-efficiency detection processes. Using robust coherent states of light, high-efficiency homodyne detection, and a deterministic......Interference of light fields plays an important role in various high-precision measurement schemes. It has been shown that superresolving phase measurements beyond the standard coherent state limit can be obtained either by using maximally entangled multiparticle states of light or using complex...... binarization processing technique, we show a narrowing of the interference fringes that scales with 1/√N where N is the mean number of photons of the coherent state. Experimentally we demonstrate a 12-fold narrowing at the shot noise limit....
Resolving fundamental limits of adhesive bonding in microfabrication.
Energy Technology Data Exchange (ETDEWEB)
Hall, Jessica S.; Frischknecht, Amalie Lucile; Emerson, John Allen; Adkins, Douglas Ray; Kent, Michael Stuart; Read, Douglas H.; Giunta, Rachel Knudsen; Lamppa, Kerry P.; Kawaguchi, Stacie; Holmes, Melissa A.
2004-04-01
As electronic and optical components reach the micro- and nanoscales, efficient assembly and packaging require the use of adhesive bonds. This work focuses on resolving several fundamental issues in the transition from macro- to micro- to nanobonding. A primary issue is that, as bondline thicknesses decrease, knowledge of the stability and dewetting dynamics of thin adhesive films is important to obtain robust, void-free adhesive bonds. While researchers have studied dewetting dynamics of thin films of model, non-polar polymers, little experimental work has been done regarding dewetting dynamics of thin adhesive films, which exhibit much more complex behaviors. In this work, the areas of dispensing small volumes of viscous materials, capillary fluid flow, surface energetics, and wetting have all been investigated. By resolving these adhesive-bonding issues, we are allowing significantly smaller devices to be designed and fabricated. Simultaneously, we are increasing the manufacturability and reliability of these devices.
Interferometer readout-noise below the Standard Quantum Limit of a membrane
Westphal, Tobias; Kaufer, Henning; Yamamoto, Kazuhiro; Gossler, Stefan; Mueller-Ebhardt, Helge; Danilishin, Stefan L; Khalili, Farid Ya; Danzmann, Karsten; Schnabel, Roman
2011-01-01
Here we report on the realization of a Michelson-Sagnac interferometer whose purpose is the precise characterization of the motion of membranes showing significant light transmission. Our interferometer has a readout noise spectral density (imprecision) of 3E-16 m/sqrt(Hz) at frequencies around the fundamental resonance of a SiN_x membrane at about 100 kHz, without using optical cavities. The readout noise demonstrated is more than 16 dB below the peak value of the membrane's standard quantum limit (SQL). This reduction is significantly higher than those of previous works with nano-wires [Teufel et al., Nature Nano. 4, 820 (2009); Anetsberger et al., Nature Phys. 5, 909 (2009)]. We discuss the meaning of the SQL for force measurements and its relation to the readout performance and conclude that neither our nor previous experiments achieved a total noise spectral density as low as the SQL.
Measurement noise 100 times lower than the quantum-projection limit using entangled atoms.
Hosten, Onur; Engelsen, Nils J; Krishnakumar, Rajiv; Kasevich, Mark A
2016-01-28
Quantum metrology uses quantum entanglement--correlations in the properties of microscopic systems--to improve the statistical precision of physical measurements. When measuring a signal, such as the phase shift of a light beam or an atomic state, a prominent limitation to achievable precision arises from the noise associated with the counting of uncorrelated probe particles. This noise, commonly referred to as shot noise or projection noise, gives rise to the standard quantum limit (SQL) to phase resolution. However, it can be mitigated down to the fundamental Heisenberg limit by entangling the probe particles. Despite considerable experimental progress in a variety of physical systems, a question that persists is whether these methods can achieve performance levels that compare favourably with optimized conventional (non-entangled) systems. Here we demonstrate an approach that achieves unprecedented levels of metrological improvement using half a million (87)Rb atoms in their 'clock' states. The ensemble is 20.1 ± 0.3 decibels (100-fold) spin-squeezed via an optical-cavity-based measurement. We directly resolve small microwave-induced rotations 18.5 ± 0.3 decibels (70-fold) beyond the SQL. The single-shot phase resolution of 147 microradians achieved by the apparatus is better than that achieved by the best engineered cold atom sensors despite lower atom numbers. We infer entanglement of more than 680 ± 35 particles in the atomic ensemble. Applications include atomic clocks, inertial sensors, and fundamental physics experiments such as tests of general relativity or searches for electron electric dipole moment. To this end, we demonstrate an atomic clock measurement with a quantum enhancement of 10.5 ± 0.3 decibels (11-fold), limited by the phase noise of our microwave source.
Shot-noise-limited optical Faraday polarimetry with enhanced laser noise cancelling
Energy Technology Data Exchange (ETDEWEB)
Li, Jiaming [School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202 (United States); Luo, Le, E-mail: leluo@iupui.edu; Carvell, Jeff; Cheng, Ruihua [Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202 (United States); Lai, Tianshu, E-mail: stslts@mail.sysu.edu.cn; Wang, Zixin, E-mail: wangzix@mail.sysu.edu.cn [School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)
2014-03-14
We present a shot-noise-limited measurement of optical Faraday rotations with sub-ten-nanoradian angular sensitivity. This extremely high sensitivity is achieved by using electronic laser noise cancelling and phase sensitive detection. Specially, an electronic laser noise canceller with a common mode rejection ratio of over 100 dB was designed and built for enhanced laser noise cancelling. By measuring the Faraday rotation of ambient air, we demonstrate an angular sensitivity of up to 9.0×10{sup −9} rad/√(Hz), which is limited only by the shot-noise of the photocurrent of the detector. To date, this is the highest angular sensitivity ever reported for Faraday polarimeters in the absence of cavity enhancement. The measured Verdet constant of ambient air, 1.93(3)×10{sup −9}rad/(G cm) at 633 nm wavelength, agrees extremely well with the earlier experiments using high finesse optical cavities. Further, we demonstrate the applications of this sensitive technique in materials science by measuring the Faraday effect of an ultrathin iron film.
Fundamental statistical limitations of future dark matter direct detection experiments
Strege, C.; Trotta, F.; Bertone, G.; Peter, A.H.G.; Scott, P.
2012-01-01
We discuss irreducible statistical limitations of future ton-scale dark matter direct detection experiments. We focus in particular on the coverage of confidence intervals, which quantifies the reliability of the statistical method used to reconstruct the dark matter parameters and the bias of the r
Null polarimetry near shot noise limit at 1 Hz.
He, Dechao; Xie, Boya; Feng, Sheng
2016-04-01
We describe the principle and report on the realization of a null polarimeter with two demonstrated features: (1) the sensitivity of the system is near shot noise limit and (2) quasi-stationary signals at 1 Hz can be measured without signal modulation. The achieved single-pass sensitivity is 7 × 10(-9) rad/Hz with a pair of Glan-Taylor polarizers, which should be of great interest for experiments such as observation of vacuum magnetic birefringence and search for new particles. The system is brought near its shot noise limit by appropriate polarization control and coherent heterodyne detection of light, resulting in a sensitivity improvement by two orders of magnitude in comparison with the case of no control on light polarization.
Fundamental and practical limits of planar tracking solar concentrators.
Grede, Alex J; Price, Jared S; Giebink, Noel C
2016-12-26
Planar microtracking provides an alternate paradigm for solar concentration that offers the possibility of realizing high-efficiency embedded concentrating photovoltaic systems in the form factor of standard photovoltaic panels. Here, we investigate the thermodynamic limit of planar tracking optical concentrators and establish that they can, in principal, achieve the sine limit of their orientationally-tracked counterparts provided that the receiver translates a minimum distance set by the field of view half-angle. We develop a phase space methodology to optimize practical planar tracking concentrators and apply it to the design of a two surface, catadioptric system that operates with > 90% optical efficiency over a 140° field of view at geometric gains exceeding 1000×. These results provide a reference point for subsequent developments in the field and indicate that planar microtracking can achieve the high optical concentration ratio required in commercial concentrating photovoltaic systems.
Fundamental limits to collective concentration sensing in cell populations
Fancher, Sean
2016-01-01
The precision of concentration sensing is improved when cells communicate. Here we derive the physical limits to concentration sensing for cells that communicate over short distances by directly exchanging small molecules (juxtacrine signaling), or over longer distances by secreting and sensing a diffusive messenger molecule (autocrine signaling). In the latter case, we find that the optimal cell spacing can be large, due to a tradeoff between maintaining communication strength and reducing signal cross-correlations. This leads to the surprising result that autocrine signaling allows more precise sensing than juxtacrine signaling for sufficiently large populations. We compare our results to data from a wide variety of communicating cell types.
Fundamental Limits to Collective Concentration Sensing in Cell Populations
Fancher, Sean; Mugler, Andrew
2017-02-01
The precision of concentration sensing is improved when cells communicate. Here we derive the physical limits to concentration sensing for cells that communicate over short distances by directly exchanging small molecules (juxtacrine signaling), or over longer distances by secreting and sensing a diffusive messenger molecule (autocrine signaling). In the latter case, we find that the optimal cell spacing can be large, due to a trade-off between maintaining communication strength and reducing signal cross-correlations. This leads to the surprising result that sparsely packed communicating cells sense concentrations more precisely than densely packed communicating cells. We compare our results to data from a wide variety of communicating cell types.
Fundamental Photoemission Brightness Limit from Disorder Induced Heating
Maxson, Jared; Coleman-Smith, Christopher; Wan, Weishi; Padmore, Howard
2013-01-01
We determine the limit of the highest achievable photoemitted electron brightness, due to heating just after emission into vacuum, applicable to both relativistic and nonrelativistic photoelectron production. This heating is due to poorly screened Coulomb interactions equivalent to disorder induced heating seen in ultracold neutral plasmas. Owing to the multi-scale nature of the initial interactions of such systems, an N-body tree algorithm is used to compute the universal scaling of the disorder induced heating in fully contained bunches, and is shown to agree well with a simple model utilizing the tabulated correlated energy of one component plasmas. We also present simulations for beams undergoing Coulomb explosion at the photocathode, and demonstrate that both the temperature growth and subsequent cooling must be characterized by correlated effects, as well as correlation-frozen dynamics. In either case, the induced temperature is found to be of several meV for typical photoinjector beam densities, a sign...
Limits on the space-time variations of fundamental constants
Levshakov, S A; Reimers, D; Molaro, P
2013-01-01
We report on new tests that improve our previous (2009-2010) estimates of the electron-to-proton mass ratio variation, mu = m_e/m_p. Subsequent observations (2011-2013) at the Effelsberg 100-m telescope of a sample of eight molecular cores from the Milky Way disk reveal systematic errors in the measured sky frequencies varying with an amplitude +/-0.01 km/s during the exposure time. The averaged offset between the radial velocities of the NH3(1,1), HC3N(2-1), HC5N(9-8), HC7N(16-15), HC7N(21-20), and HC7N(23-22) transitions gives Delta V = 0.002 +/- 0.015 km/s (3 sigma C.L.). This value, when interpreted in terms of Delta mu/mu = (mu_obs - mu_lab)/mu_lab constraints the mu-variation at the level of Delta mu/mu < 2x10^{-8} (3 sigma C.L.), which is the most stringent limit on the fractional changes in mu based on radio astronomical observations. If variation of the fine-structure constant alpha is coupled with mu, then within the grand unification model one may expect locally the spacial changes |Delta alpha/...
Secret Key Agreement: Fundamental Limits and Practical Challenges
Rezki, Zouheir
2017-02-15
Despite the tremendous progress made toward establishing PLS as a new paradigm to guarantee security of communication systems at the physical layerthere is a common belief among researchers and industrials that there are many practical challenges that prevent PLS from flourishing at the industrial scale. Most secure message transmission constructions available to date are tied to strong assumptions on CSI, consider simple channel models and undermine eavesdropping capabilities; thus compromising their practical interest to a big extent. Perhaps arguably, the most likely reasonable way to leverage PLS potential in securing modern wireless communication systems is via secret-key agreement. In the latter setting, the legitimate parties try to agree on a key exploiting availability of a public channel with high capacity which is also accessible to the eavesdropper. Once a key is shared by the legitimate parties, they may use it in a one-time pad encryption, for instance. In this article, we investigate two performance limits of secret-key agreement communications; namely, the secret-key diversity-multiplexing trade-off and the effect of transmit correlation on the secretkey capacity. We show via examples how secretkey agreement offers more flexibility than secure message transmissions. Finally, we explore a few challenges of secret-key agreement concept and propose a few guidelines to overturn them.
Statistical Angular Resolution Limit for Ultrawideband MIMO Noise Radar
Directory of Open Access Journals (Sweden)
Xiaoli Zhou
2015-01-01
Full Text Available The two-dimensional angular resolution limit (ARL of elevation and azimuth for MIMO radar with ultrawideband (UWB noise waveforms is investigated using statistical resolution theory. First, the signal model of monostatic UWB MIMO noise radar is established in a 3D reference frame. Then, the statistical angular resolution limits (SARLs of two closely spaced targets are derived using the detection-theoretic and estimation-theoretic approaches, respectively. The detection-theoretic approach is based on the generalized likelihood ratio test (GLRT with given probabilities of false alarm and detection, while the estimation-theoretic approach is based on Smith’s criterion which involves the Cramér-Rao lower bound (CRLB. Furthermore, the relationship between the two approaches is presented, and the factors affecting the SARL, that is, detection parameters, transmit waveforms, array geometry, signal-to-noise ratio (SNR, and parameters of target (i.e., radar cross section (RCS and direction, are analyzed. Compared with the conventional radar resolution theory defined by the ambiguity function, the SARL reflects the practical resolution ability of radar and can provide an optimization criterion for radar system design.
A numerical study of fundamental shock noise mechanisms. Ph.D. Thesis - Cornell Univ.
Meadows, Kristine R.
1995-01-01
The results of this thesis demonstrate that direct numerical simulation can predict sound generation in unsteady aerodynamic flows containing shock waves. Shock waves can be significant sources of sound in high speed jet flows, on helicopter blades, and in supersonic combustion inlets. Direct computation of sound permits the prediction of noise levels in the preliminary design stage and can be used as a tool to focus experimental studies, thereby reducing cost and increasing the probability of a successfully quiet product in less time. This thesis reveals and investigates two mechanisms fundamental to sound generation by shocked flows: shock motion and shock deformation. Shock motion is modeled by the interaction of a sound wave with a shock. During the interaction, the shock wave begins to move and the sound pressure is amplified as the wave passes through the shock. The numerical approach presented in this thesis is validated by the comparison of results obtained in a quasi-one dimensional simulation with linear theory. Analysis of the perturbation energy demonstrated for the first time that acoustic energy is generated by the interaction. Shock deformation is investigated by the numerical simulation of a ring vortex interacting with a shock. This interaction models the passage of turbulent structures through the shock wave. The simulation demonstrates that both acoustic waves and contact surfaces are generated downstream during the interaction. Analysis demonstrates that the acoustic wave spreads cylindrically, that the sound intensity is highly directional, and that the sound pressure level increases significantly with increasing shock strength. The effect of shock strength on sound pressure level is consistent with experimental observations of shock noise, indicating that the interaction of a ring vortex with a shock wave correctly models a dominant mechanism of shock noise generation.
Beat Noise Limitation in Coherent Time-Spreading OCDMA Network
Institute of Scientific and Technical Information of China (English)
Ken-ichi; Kitayama; Koji; Mutsushima
2003-01-01
The BER performance of the coherent time-spreading OCDMA network is analyzed by considering the MAI and beat noises as well as the other additive noises. The influence and solution for the beat noise issue are discussed.
Noise and physical limits to maximum resolution of PET images
Energy Technology Data Exchange (ETDEWEB)
Herraiz, J.L.; Espana, S. [Dpto. Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain); Vicente, E.; Vaquero, J.J.; Desco, M. [Unidad de Medicina y Cirugia Experimental, Hospital GU ' Gregorio Maranon' , E-28007 Madrid (Spain); Udias, J.M. [Dpto. Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain)], E-mail: jose@nuc2.fis.ucm.es
2007-10-01
In this work we show that there is a limit for the maximum resolution achievable with a high resolution PET scanner, as well as for the best signal-to-noise ratio, which are ultimately related to the physical effects involved in the emission and detection of the radiation and thus they cannot be overcome with any particular reconstruction method. These effects prevent the spatial high frequency components of the imaged structures to be recorded by the scanner. Therefore, the information encoded in these high frequencies cannot be recovered by any reconstruction technique. Within this framework, we have determined the maximum resolution achievable for a given acquisition as a function of data statistics and scanner parameters, like the size of the crystals or the inter-crystal scatter. In particular, the noise level in the data as a limitation factor to yield high-resolution images in tomographs with small crystal sizes is outlined. These results have implications regarding how to decide the optimal number of voxels of the reconstructed image or how to design better PET scanners.
Noise pollution has limited effects on nocturnal vigilance in peahens
Hermann, Fredrick S.
2016-01-01
Natural environments are increasingly exposed to high levels of noise pollution. Noise pollution can alter the behavior of animals but we know little about its effects on antipredator behavior. We therefore investigated the impact of noise pollution on vigilance behavior and roost selection in an avian species, peafowl (Pavo cristatus), that inhabits urban environments. Captive peahens were exposed to noise pollution at night and their vigilance levels and roost selections were monitored. The vigilance levels of peahens were unaffected by exposure to noise pollution within trials. Furthermore, the peahens exhibited no preference for roosting farther or closer to noise pollution. Interestingly, predators often avoided the experimental area during nights with noise pollution, which could explain why vigilance rates were higher overall during control compared to noise trials. The results suggest that peahens’ perception of risk is not drastically impacted by noise pollution but longer-term studies will be necessary to assess any chronic effects. PMID:27703863
Noise limits of CMOS current interfaces for biosensors: a review.
Crescentini, Marco; Bennati, Marco; Carminati, Marco; Tartagni, Marco
2014-04-01
Current sensing readout is one of the most frequent techniques used in biosensing due to the charge-transfer phenomena occurring at solid-liquid interfaces. The development of novel nanodevices for biosensing determines new challenges for electronic interface design based on current sensing, especially when compact and efficient arrays need to be organized, such as in recent trends of rapid label-free electronic detection of DNA synthesis. This paper will review the basic noise limitations of current sensing interfaces with particular emphasis on integrated CMOS technology. Starting from the basic theory, the paper presents, investigates and compares charge-sensitive amplifier architectures used in both continuous-time and discrete-time approaches, along with their design trade-offs involving noise floor, sensitivity to stray capacitance and bandwidth. The ultimate goal of this review is providing analog designers with helpful design rules and analytical tools. Also, in order to present a comprehensive overview of the state-of-the-art, the most relevant papers recently appeared in the literature about this topic are discussed and compared.
Fundamental dispersion limit for spectrally bounded On-Off-Keying communication channels
Granot, Er'el
2012-01-01
The fundamental dispersion limit for optical communication based the On-Off-Keying format is calculated. It is shown both analytically and with numerical simulations that an OOK optical sequence, which passes through spectrally narrow noncompensated dispersive channel cannot exceed the limit 1/{\\pi} > {\\beta_2} L B^2, where {\\beta_2}, L and B are the dispersion coefficient, the fiber's length and the bit-rate respectively. To the best of our knowledge, this is the first time that such a fundamental limit was formulated. In the literature, only approximation evaluations were developed yielding much smaller limiting values.
Weak lensing at the limit of the sky background noise
Mellier, Y
1996-01-01
Recent weak lensing observations have pushed the use of 4 meter-class telescopes to the limits of their capabilities with exposure times exceeding several hours. The leading idea is that the surface density of faint galaxies up to very faint magnitude ($B > 28-30$) raises continuously thus potentially offering a dense template of distant sources whose intensity contrast is at the sky noise level. In complement to the Peter Schneider's presentation on dark matter search from weak lensing (this conference), we review some of these recent advances in weak lensing analysis based on this extreme faint population of galaxies in order to explore: the dark matter distribution on large scales, the redshift ditribution of lensed sources at very large distance, and eventually the values of cosmological parameters. For each observational topic we will briefly discuss these new methods as compare to more classical lensing studies as well as the possible VLT scientific impact in the domain.
Shafei, Shoresh; Kuzyk, Mark C.; Kuzyk, Mark G.
2010-03-01
The hyperpolarizability governs all light-matter interactions. In recent years, quantum mechanical calculations have shown that there is a fundamental limit of the hyperpolarizability of all materials. The fundamental limits are calculated only under the assumption that the Thomas Kuhn sum rules and the three-level ansatz hold. (The three-level ansatz states that for optimized hyperpolarizability, only two excited states contribute to the hyperpolarizability.) All molecules ever characterized have hyperpolarizabilities that fall well below the limits. However, Monte Carlo simulations of the nonlinear polarizability have shown that attaining values close to the fundamental limit is theoretically possible; but, the calculations do not provide guidance with regards to what potentials are optimized. The focus of our work is to use Monte Carlo techniques to determine sets of energies and transition moments that are consistent with the sum rules, and study the constraints on their signs. This analysis will be used to implement a numerical proof of three-level ansatz.
Oblak, D; Tittel, W; Vershovski, A K; Sørensen, J L; Petrov, P G; Alzar, C L G; Polzik, E S; Oblak, Daniel; Mikkelsen, Jens K.; Tittel, Wolfgang; Vershovski, Anton K.; Sorensen, Jens L.; Petrov, Plamen G.; Alzar, Carlos L. Garrido; Polzik, Eugene S.
2003-01-01
We investigate theoretically and experimentally a nondestructive interferometric measurement of the state population of an ensemble of laser cooled and trapped atoms. This study is a step towards generation of (quasi-) spin squeezing of cold atoms targeted at the improvement of the Caesium clock performance beyond the limit set by the quantum projection noise of atoms. We propose a protocol for the sequence of operations required to generate and utilize spin squeezing for the improved microwave clock performance via a quantum nondemolition measurement (qnd) on the probe light. We calculate the phase shift and the quantum noise of a near resonant optical probe pulse propagating through a cloud of cold 133Cs atoms. We analyze the figure of merit for a qnd measurement of the collective quasi-spin and show that it can be expressed simply as a product of the ensemble optical depth and the probability of the spontaneous emission caused by the off-resonant probe light. In the experimental part we report on the preli...
Werle, P; Slemr, F; Gehrtz, M; Bräuchle, C
1989-05-01
The wideband noise characteristics of a PbEuSe molecular beam epitaxy diode laser have been measured up to 500 MHz. The cutoff of the frequency dependent (1/f type) laser noise contribution was found to be 170 MHz for this particular laser. Above this cutoff frequency the photon shot noise dominates, as was demonstrated. A noise reduction of more than 2 orders of magnitude was observed in the shot noise limited domain when compared with the 1/f noise dominated region below 1 MHz. This finding indicates that a similar 2 orders of magnitude sensitivity improvement can be achieved in tunable diode laser absorption spectroscopy when frequency modulation techniques are applied instead of the more conventional derivative modulation below 1 MHz.
Lee, Shao-Hsuan; Hsiao, Tzu-Yu; Lee, Guo-She
2015-06-01
Sustained vocalizations of vowels [a], [i], and syllable [mə] were collected in twenty normal-hearing individuals. On vocalizations, five conditions of different audio-vocal feedback were introduced separately to the speakers including no masking, wearing supra-aural headphones only, speech-noise masking, high-pass noise masking, and broad-band-noise masking. Power spectral analysis of vocal fundamental frequency (F0) was used to evaluate the modulations of F0 and linear-predictive-coding was used to acquire first two formants. The results showed that while the formant frequencies were not significantly shifted, low-frequency modulations (production, the motor speech controls on F0 may depend on a feedback mechanism while articulation should rely more on a feedforward mechanism. Power spectral analysis of F0 might be applied to evaluate audio-vocal control for various hearing and neurological disorders in the future. Copyright © 2015 Elsevier B.V. All rights reserved.
Dynamic Vehicle Routing for Robotic Networks: Models, Fundamental Limitations and Algorithms
2010-04-16
partitions. SIAM Review, January 2010. Submitted Francesco Bullo (UCSB) Dynamic Vehicle Routing 16apr10 @ ARL 31 / 34 Gossip partitioning policy: sample...Control Conference, Hollywood, CA, October 2009 Francesco Bullo (UCSB) Dynamic Vehicle Routing 16apr10 @ ARL 32 / 34 Gossip partitioning policy: analysis...Dynamic Vehicle Routing for Robotic Networks: Models, Fundamental Limitations and Algorithms Francesco Bullo Center for Control, Dynamical Systems
Hugonin, Jean-Paul; Ben-Abdallah, Philippe
2015-01-01
Absorption and scattering of electromagnetic waves by dielectric media are of fundamental importance in many branches of physics. In this Letter we analytically derived the ultimate upper limits for the absorbed and scattered powers by any system of optical resonators in mutual interaction. We show that these bounds depend only on the geometric configuration given an incident field. We give the conditions to fullfill to reach these limits paving so a way for a rational design of optimal metamaterials.
Are there fundamental limits for observing quantum phenomena from within quantum theory?
Kofler, Johannes
2010-01-01
Does there exist a limit for the applicability of quantum theory for objects of large mass or size, or objects whose states are of large complexity or dimension of the Hilbert space? The possible answers range from practical limitations due to decoherence within quantum theory to fundamental limits due to collapse models that modify quantum theory. Here, we suggest the viewpoint that there might be also fundamental limits without altering the quantum laws. We first demonstrate that for two quantum spins systems of a given spin length, no violation of local realism can be observed, if the measurements are sufficiently coarse-grained. Then we show that there exists a fundamental limit for the precision of measurements due to (i) the Heisenberg uncertainty relation which has to be applied to the measuring apparatus, (ii) relativistic causality, and (iii) the finiteness of resources in any laboratory including the whole universe. This suggests that there might exist a limit for the size of the systems (dimension ...
Passive synthetic aperture imaging with limited noise sources
Garnier, Josselin
2016-09-01
We consider a passive synthetic aperture imaging problem. A single moving receiver antenna records random signals generated by one or several distant noise sources and backscattered by one or several reflectors. The sources emit noise signals modeled by stationary random processes. The reflectors can be imaged by summing the autocorrelation functions of the received signals computed over successive time windows, corrected for Doppler factors and migrated by appropriate travel times. In particular, the Doppler effect plays an important role and it can be used for resolution enhancement. When the noise source positions are not known, the reflector can be localized with an accuracy proportional to the reciprocal of the noise bandwidth, even when only a very small number of sources are available. When the noise source positions are known, the reflector can be localized with a cross range resolution proportional to the carrier wavelength and inversely proportional to the length of the receiver trajectory (i.e. the synthetic aperture), and with a range resolution proportional to the reciprocal of the bandwidth, even with only one noise source.
Pérez-Moreno, Javier; Clays, Koen
The generalized Thomas-Kuhn sum rules are used to characterize the nonlinear optical response of organic chromophores in terms of fundamental parameters that can be measured experimentally. The nonlinear optical performance of organic molecules is evaluated from the combination of hyper-Rayleigh scattering measurements and the analysis in terms of the fundamental limits. Different strategies for the enhancement of nonlinear optical behavior at the molecular and supramolecular level are evaluated and new paradigms for the design of more efficient nonlinear optical molecules are proposed and investigated.
Parbery-Clark, Alexandra; Skoe, Erika; Kraus, Nina
2009-11-11
Musicians have lifelong experience parsing melodies from background harmonies, which can be considered a process analogous to speech perception in noise. To investigate the effect of musical experience on the neural representation of speech-in-noise, we compared subcortical neurophysiological responses to speech in quiet and noise in a group of highly trained musicians and nonmusician controls. Musicians were found to have a more robust subcortical representation of the acoustic stimulus in the presence of noise. Specifically, musicians demonstrated faster neural timing, enhanced representation of speech harmonics, and less degraded response morphology in noise. Neural measures were associated with better behavioral performance on the Hearing in Noise Test (HINT) for which musicians outperformed the nonmusician controls. These findings suggest that musical experience limits the negative effects of competing background noise, thereby providing the first biological evidence for musicians' perceptual advantage for speech-in-noise.
Thomas, Drew M
2012-01-01
Although the state of living organisms is affected by many interrelated and unidentified variables, one need not invoke this to explain the "Truth Wears Off" or "decline" effect, and this complexity imposes no fundamental limitation on statistical inference. Similar "decline" effects occur in physics as well as the biomedical sciences; selective reporting and publication bias, and scientists' biases in favour of reporting eye-catching results (in biomedical sciences and psychology) or conforming to others' results (in physics) better explain this feature of the "Truth Wears Off" effect than Rabin's suggested limitation on statistical inference.
LOW-NOISE PAVEMENT AS A WAY OF LIMITATION OF TRAFFIC NOISE LEVEL
Directory of Open Access Journals (Sweden)
Władysław Gardziejczyk
2014-11-01
Full Text Available Road surface can significantlyreduce the trafficnoise level. Depending on the characteristic of the upper surface layers the differences between the maximum rolling noise levels from passing vehicles to reach values about 10 dB (A. A special group is low-noise pavements characterized by the presence of voids above 15%. Application the porous asphalt layers or asphalt mixture type BBTM affects a significantreduction the width of land surrounded the roads where permissible equivalent sound level is exceeded. Such solutions in some cases can replace acoustic barriers. Road pavements with a higher content of voids require proper maintenance because their acoustic performances are reduced during operation.
Broadband noise limit in the photodetection of ultralow jitter optical pulses.
Sun, Wenlu; Quinlan, Franklyn; Fortier, Tara M; Deschenes, Jean-Daniel; Fu, Yang; Diddams, Scott A; Campbell, Joe C
2014-11-14
Applications with optical atomic clocks and precision timing often require the transfer of optical frequency references to the electrical domain with extremely high fidelity. Here we examine the impact of photocarrier scattering and distributed absorption on the photocurrent noise of high-speed photodiodes when detecting ultralow jitter optical pulses. Despite its small contribution to the total photocurrent, this excess noise can determine the phase noise and timing jitter of microwave signals generated by detecting ultrashort optical pulses. A Monte Carlo simulation of the photodetection process is used to quantitatively estimate the excess noise. Simulated phase noise on the 10 GHz harmonic of a photodetected pulse train shows good agreement with previous experimental data, leading to the conclusion that the lowest phase noise photonically generated microwave signals are limited by photocarrier scattering well above the quantum limit of the optical pulse train.
Magnusson, Lennart; Claesson, Ann; Persson, Maria; Tengstrand, Tomas
2013-01-01
To investigate speech recognition performance in noise with bilateral open-fit hearing aids and as reference also with closed earmolds, in omnidirectional mode, directional mode, and directional mode in conjunction with noise reduction. A within-subject design with repeated measures across conditions was used. Speech recognition thresholds in noise were obtained for the different conditions. Twenty adults without prior experience with hearing aids. All had symmetric sensorineural mild hearing loss in the lower frequencies and moderate to severe hearing loss in the higher frequencies. Speech recognition performance in noise was not significantly better with an omnidirectional microphone compared to unaided, whereas performance was significantly better with a directional microphone (1.6 dB with open fitting and 4.4 dB with closed earmold) compared to unaided. With open fitting, no significant additional advantage was obtained by combining the directional microphone with a noise reduction algorithm, but with closed earmolds a significant additional advantage of 0.8 dB was obtained. The significant, though limited, advantage of directional microphones and the absence of additional significant improvement by a noise reduction algorithm should be considered when fitting open-fit hearing aids.
Pico Veleta Atmospheric Noise Limits at Millimeter Wavelengths
Benford, Dominic J.
2010-01-01
In November 2007 and October 2008, we demonstrated a new camera for the 2 mm wavelength band, GISMO (Goddard IRAM Superconducting 2 Millimeter Observer), at the IRAM 30 m telescope in Spain. Based on a novel superconducting transition edge sensor bolometer array, GISMO features a compact optical design that should provide rapid imaging in its band. We detail the calculations made for GISMO to determine the atmospheric emission optical loading and resultant photon noise in the 2 mm band at Pico Veleta, and show confirming measurements obtained during the observing runs.
Beyond the current noise limit in imaging through turbulent medium
Popowicz, A; Pollo, A; Smolka, B
2015-01-01
Shift-and-add is an approach employed to mitigate the phenomenon of resolution degradation in images acquired through a turbulent medium. Using this technique, a large number of consecutive short exposures is registered below the coherence time of the atmosphere or other blurring medium. The acquired images are shifted to the position of the brightest speckle and stacked together to obtain high-resolution and high signal-to-noise frame. In this paper we present a highly efficient method for determination of frames shifts, even if in a single frame the object cannot be distinguished from the background noise. The technique utilizes our custom genetic algorithm, which iteratively evolves a set of image shifts. We used the maximal energy of stacked images as an objective function for shifts estimation and validate the efficiency of the method on simulated and real images of simple and complex sources. Obtained results confirmed, that our proposed method allows for the recovery of spatial distribution of objects ...
Optical measurements of phase steps in segmented mirrors - fundamental precision limits
Noethe, L
2006-01-01
Phase steps are an important type of wavefront aberrations generated by large telescopes with segmented mirrors. In a closed-loop correction cycle these phase steps have to be measured with the highest possible precision using natural reference stars, that is with a small number of photons. In this paper the classical Fisher information of statistics is used for calculating the Cramer-Rao bound, which determines the limit to the precision with which the height of the steps can be estimated in an unbiased fashion with a given number of photons and a given measuring device. Four types of measurement devices are discussed: a Shack-Hartmann sensor with one small cylindrical lenslet covering a sub-aperture centred over a border, a modified Mach-Zehnder interferometer, a Foucault test, and a curvature sensor. The Cramer-Rao bound is calculated for all sensors under ideal conditions, that is narrowband measurements without additional noise or disturbances apart from the photon shot noise. This limit is compared with...
Asynchronous CDMA Systems with Random Spreading-Part I: Fundamental Limits
Cottatellucci, Laura; Debbah, Merouane
2009-01-01
Spectral efficiency for asynchronous code division multiple access (CDMA) with random spreading is calculated in the large system limit allowing for arbitrary chip waveforms and frequency-flat fading. Signal to interference and noise ratios (SINRs) for suboptimal receivers, such as the linear minimum mean square error (MMSE) detectors, are derived. The approach is general and optionally allows even for statistics obtained by under-sampling the received signal. All performance measures are given as a function of the chip waveform and the delay distribution of the users in the large system limit. It turns out that synchronizing users on a chip level impairs performance for all chip waveforms with bandwidth greater than the Nyquist bandwidth, e.g., positive roll-off factors. For example, with the pulse shaping demanded in the UMTS standard, user synchronization reduces spectral efficiency up to 12% at 10 dB normalized signal-to-noise ratio. The benefits of asynchronism stem from the finding that the excess bandw...
Effects of Noises on Fujisakiâs Model of Fundamental Frequency Contours for Thai Dialects
Directory of Open Access Journals (Sweden)
Suphattharachai Chomphan
2012-01-01
Full Text Available Problem statement: Modeling of fundamental frequency (F0 contour plays an important role on the natural speech processing, since F0 is an important speech feature defining the human speech prosody. In Thai, there are four main dialects spoken by Thai people residing in four core region including central, north, northeast and south regions. Environmental noises are also plays an important role in corrupting the speech quality. The study of effects of noises on modeling of F0 contour for Thai dialects will evaluate robustness of the modeling techniques. Approach: The Fujisakiâs model has been selected in this study because of its achievement in modeling of various Thai speech units. Four types of environmental noises are simulated with different levels of power. The differences among the model parameters of four Thai dialects have been summarized. This study proposes an analysis of model parameters for Thai speech prosody with four regional dialects and two genders and four types of noises. Seven derived parameters from the Fujisakiâs model are as follows. The first parameter is baseline frequency which is the lowest level of F0 contour. The second and third parameters are the numbers of phrase commands and tone commands which reflect the frequencies of surges of the utterance in global and local levels, respectively. The fourth and fifth parameters are phrase command and tone command durations which reflect the speed of speaking and the length of a syllable, respectively. The sixth and seventh parameters are amplitudes of phrase command and tone command which reflect the energy of the global speech and the energy of local syllable. Results: In the experiments, each regional dialect includes 10 samples of 10 sentences with male and female speech. Four types of noises include train, factory, car and air conditioner. Moreover, five levels of each type of noise are varied from 0-20 dB. The results show that most of the proposed parameters
Potential Impact of Latest Proposals for New European Vehicle Noise Limits
Dittrich, M.G.; Roo, F. de
2013-01-01
Noise emission of new road vehicles is regulated by European Directives [1] and subsequent amendments. Proposals for tighter noise emission limits for road vehicles made by the European Commission in 2011 [2] have been adopted in modified form by the European Parliament in 2013 [3]. In the VENOLIVA
Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy
Directory of Open Access Journals (Sweden)
Jannis Lübbe
2013-01-01
Full Text Available The noise of the frequency-shift signal Δf in noncontact atomic force microscopy (NC-AFM consists of cantilever thermal noise, tip–surface-interaction noise and instrumental noise from the detection and signal processing systems. We investigate how the displacement-noise spectral density dz at the input of the frequency demodulator propagates to the frequency-shift-noise spectral density dΔf at the demodulator output in dependence of cantilever properties and settings of the signal processing electronics in the limit of a negligible tip–surface interaction and a measurement under ultrahigh-vacuum conditions. For a quantification of the noise figures, we calibrate the cantilever displacement signal and determine the transfer function of the signal-processing electronics. From the transfer function and the measured dz, we predict dΔf for specific filter settings, a given level of detection-system noise spectral density dzds and the cantilever-thermal-noise spectral density dzth. We find an excellent agreement between the calculated and measured values for dΔf. Furthermore, we demonstrate that thermal noise in dΔf, defining the ultimate limit in NC-AFM signal detection, can be kept low by a proper choice of the cantilever whereby its Q-factor should be given most attention. A system with a low-noise signal detection and a suitable cantilever, operated with appropriate filter and feedback-loop settings allows room temperature NC-AFM measurements at a low thermal-noise limit with a significant bandwidth.
Saxena, Samveg
2013-10-01
Low temperature combustion (LTC) engines are an emerging engine technology that offers an alternative to spark-ignited and diesel engines. One type of LTC engine, the homogeneous charge compression ignition (HCCI) engine, uses a well-mixed fuel–air charge like spark-ignited engines and relies on compression ignition like diesel engines. Similar to diesel engines, the use of high compression ratios and removal of the throttling valve in HCCI allow for high efficiency operation, thereby allowing lower CO2 emissions per unit of work delivered by the engine. The use of a highly diluted well-mixed fuel–air charge allows for low emissions of nitrogen oxides, soot and particulate matters, and the use of oxidation catalysts can allow low emissions of unburned hydrocarbons and carbon monoxide. As a result, HCCI offers the ability to achieve high efficiencies comparable with diesel while also allowing clean emissions while using relatively inexpensive aftertreatment technologies. HCCI is not, however, without its challenges. Traditionally, two important problems prohibiting market penetration of HCCI are 1) inability to achieve high load, and 2) difficulty in controlling combustion timing. Recent research has significantly mitigated these challenges, and thus HCCI has a promising future for automotive and power generation applications. This article begins by providing a comprehensive review of the physical phenomena governing HCCI operation, with particular emphasis on high load conditions. Emissions characteristics are then discussed, with suggestions on how to inexpensively enable low emissions of all regulated emissions. The operating limits that govern the high load conditions are discussed in detail, and finally a review of recent research which expands the high load limits of HCCI is discussed. Although this article focuses on the fundamental phenomena governing HCCI operation, it is also useful for understanding the fundamental phenomena in reactivity controlled
Fundamental x-ray interaction limits in diagnostic imaging detectors: spatial resolution.
Hajdok, G; Battista, J J; Cunningham, I A
2008-07-01
The practice of diagnostic x-ray imaging has been transformed with the emergence of digital detector technology. Although digital systems offer many practical advantages over conventional film-based systems, their spatial resolution performance can be a limitation. The authors present a Monte Carlo study to determine fundamental resolution limits caused by x-ray interactions in four converter materials: Amorphous silicon (a-Si), amorphous selenium, cesium iodide, and lead iodide. The "x-ray interaction" modulation transfer function (MTF) was determined for each material and compared in terms of the 50% MTF spatial frequency and Wagner's effective aperture for incident photon energies between 10 and 150 keV and various converter thicknesses. Several conclusions can be drawn from their Monte Carlo study. (i) In low-Z (a-Si) converters, reabsorption of Compton scatter x rays limits spatial resolution with a sharp MTF drop at very low spatial frequencies (x rays plays a dominant role, resulting in a mid-frequency (1-5 cycles/mm) MTF drop. (ii) Coherent scatter plays a minor role in the x-ray interaction MTF. (iii) The spread of energy due to secondary electron (e.g., photoelectrons) transport is significant only at very high spatial frequencies. (iv) Unlike the spread of optical light in phosphors, the spread of absorbed energy from x-ray interactions does not significantly degrade spatial resolution as converter thickness is increased. (v) The effective aperture results reported here represent fundamental spatial resolution limits of the materials tested and serve as target benchmarks for the design and development of future digital x-ray detectors.
Does the central limit theorem always apply to phase noise? Some implications for radar problems
Gray, John E.; Addison, Stephen R.
2017-05-01
The phase noise problem or Rayleigh problem occurs in all aspects of radar. It is an effect that a radar engineer or physicist always has to take into account as part of a design or in attempt to characterize the physics of a problem such as reverberation. Normally, the mathematical difficulties of phase noise characterization are avoided by assuming the phase noise probability distribution function (PDF) is uniformly distributed, and the Central Limit Theorem (CLT) is invoked to argue that the superposition of relatively few random components obey the CLT and hence the superposition can be treated as a normal distribution. By formalizing the characterization of phase noise (see Gray and Alouani) for an individual random variable, the summation of identically distributed random variables is the product of multiple characteristic functions (CF). The product of the CFs for phase noise has a CF that can be analyzed to understand the limitations CLT when applied to phase noise. We mirror Kolmogorov's original proof as discussed in Papoulis to show the CLT can break down for receivers that gather limited amounts of data as well as the circumstances under which it can fail for certain phase noise distributions. We then discuss the consequences of this for matched filter design as well the implications for some physics problems.
Pasqualetti, Fabio; Bullo, Francesco
2012-01-01
Cyber-physical systems integrate computation, communication, and physical capabilities to interact with the physical world and humans. Besides failures of components, cyber-physical systems are prone to malignant attacks, and specific analysis tools as well as monitoring mechanisms need to be developed to enforce system security and reliability. This paper proposes a unified framework to analyze the resilience of cyber-physical systems against attacks cast by an omniscient adversary. We model cyber-physical systems as linear descriptor systems, and attacks as exogenous unknown inputs. Despite its simplicity, our model captures various real-world cyber-physical systems, and it includes and generalizes many prototypical attacks, including stealth, (dynamic) false-data injection and replay attacks. First, we characterize fundamental limitations of static, dynamic, and active monitors for attack detection and identification. Second, we provide constructive algebraic conditions to cast undetectable and unidentifia...
Photon Routing in Cavity QED: Beyond the Fundamental Limit of Photon Blockade
Rosenblum, Serge; Dayan, Barak
2011-01-01
The most simple and seemingly straightforward application of the photon blockade effect, in which the transport of one photon prevents the transport of others, would be to separate two incoming indistinguishable photons to different output ports. We show that time-energy uncertainty relations inherently prevent this ideal situation when the blockade is implemented by a two-level system. The fundamental nature of this limit is revealed in the fact that photon blockade in the strong coupling regime of cavity QED, resulting from the nonlinearity of the Jaynes-Cummings energy level structure, exhibits efficiency and temporal behavior identical to those of photon blockade in the bad cavity regime, where the underlying nonlinearity is that of the atom itself. We demonstrate that this limit can be exceeded, yet not avoided, by exploiting time-energy entanglement between the incident photons. Finally, we show how this limit can be circumvented completely by using a three-level atom coupled to a single-sided cavity, e...
Photon routing in cavity QED: Beyond the fundamental limit of photon blockade
Energy Technology Data Exchange (ETDEWEB)
Rosenblum, Serge; Dayan, Barak [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Parkins, Scott [Department of Physics, University of Auckland, Private Bag 92019, Auckland (New Zealand)
2011-09-15
The most simple and seemingly straightforward application of the photon blockade effect, in which the transport of one photon prevents the transport of others, would be to separate two incoming indistinguishable photons to different output ports. We show that time-energy uncertainty relations inherently prevent this ideal situation when the blockade is implemented by a two-level system. The fundamental nature of this limit is revealed in the fact that photon blockade in the strong coupling regime of cavity QED, resulting from the nonlinearity of the Jaynes-Cummings energy level structure, exhibits efficiency and temporal behavior identical to those of photon blockade in the bad cavity regime, where the underlying nonlinearity is that of the atom itself. We demonstrate that this limit can be exceeded, yet not avoided, by exploiting time-energy entanglement between the incident photons. Finally, we show how this limit can be circumvented completely by using a three-level atom coupled to a single-sided cavity, enabling an ideal and robust photon routing mechanism.
Renormalization and Central limit theorem for critical dynamical systems with weak external noise
Diaz-Espinosa, O
2006-01-01
We study of the effect of weak noise on critical one dimensional maps; that is, maps with a renormalization theory. We establish a one dimensional central limit theorem for weak noises and obtain Berry--Esseen estimates for the rate of this convergence. We analyze in detail maps at the accumulation of period doubling and critical circle maps with golden mean rotation number. Using renormalization group methods, we derive scaling relations for several features of the effective noise after long times. We use these scaling relations to show that the central limit theorem for weak noise holds in both examples. We note that, for the results presented here, it is essential that the maps have parabolic behavior. They are false for hyperbolic orbits.
Fundamental limits of super-resolution microscopy by dielectric microspheres and microfibers
Astratov, V. N.; Maslov, A. V.; Allen, K. W.; Farahi, N.; Li, Y.; Brettin, A.; Limberopoulos, N. I.; Walker, D. E.; Urbas, A. M.; Liberman, V.; Rothschild, M.
2016-03-01
In recent years, optical super-resolution by microspheres and microfibers emerged as a new paradigm in nanoscale label-free and fluorescence imaging. However, the mechanisms of such imaging are still not completely understood and the resolution values are debated. In this work, the fundamental limits of super-resolution imaging by high-index barium-titanate microspheres and silica microfibers are studied using nanoplasmonic arrays made from Au and Al. A rigorous resolution analysis is developed based on the object's convolution with the point-spread function that has width well below the conventional (~λ/2) diffraction limit, where λ is the illumination wavelength. A resolution of ~λ/6-λ/7 is demonstrated for imaging nanoplasmonic arrays by microspheres. Similar resolution was demonstrated for microfibers in the direction perpendicular to the fiber axis with hundreds of times larger field-of-view in comparison to microspheres. Using numerical solution of Maxwell's equations, it is shown that extraordinary close point objects can be resolved in the far field, if they oscillate out of phase. Possible super-resolution using resonant excitation of whispering gallery modes is also studied.
Physics of the fundamental limits of nonlinear optics: a theoretical perspective [Invited
Lytel, Rick
2016-12-01
The theory of the fundamental limits (TFL) of nonlinear optics is a powerful tool for experimentalists seeking to create molecules and materials with large responses, and for theorists who are seeking to understand how the basic elements of quantum theory delineate the boundaries within which these searches should be conducted. On a practical level, the TFL provides a metric for measuring the performance or 'goodness' of new molecules, relative to what is possible. Explorations of large sets of structures within the theory provide insight into new design rules for creating more active molecules. This article is a review of the TFL, starting with a history of its development and its first use to discover that all molecules as of the year 2000 fell a factor of 30 below the limits, and continuing to the present day where the theory continues to provide research opportunities and challenges. The review focuses on off-resonant nonlinear optics in order to sharply focus on the key elements of the TFL, but pointers are provided to the literature for near- and on-resonance applications.
Super-aperture metrology: overcoming a fundamental limit in imaging smooth highly curved surfaces.
Liu, J; Liu, C; Tan, J; Yang, B; Wilson, T
2016-03-01
The imaging of smooth, highly curved or tilted surfaces is widely recognized as one of the most challenging and unsolved problems in optical imaging and metrology today. The reason is that even when such surfaces are imaged using high aperture microscope objectives the steepness of the features causes the light to be reflected in such a way that it is not captured by the lens. This is true even in the limiting case of unity numerical aperture since the illuminating light may also be reflected in the forward direction. In order to overcome this fundamental problem we have developed a method whereby such specimens are covered with a readily removable organic fluorescent film thereby creating an isotropic scattering surface. We show that we are readily able to detect slopes with angles close 90° using a 0.75 NA objective--an 82% improvement over the theoretical aperture limit. Issues of variation in film thickness deposition are shown to be readily accommodated. This approach may be used with other fluorophore materials, organic or inorganic, since there is no need for biocompatibility in this application.
Physics of the fundamental limits of nonlinear optics: A theoretical perspective
Lytel, Rick
2016-01-01
The theory of the fundamental limits (TFL) of nonlinear optics is a powerful tool for experimentalists seeking to create molecules and materials with large responses, and for theorists who are seeking to understand how the basic elements of quantum theory delineate the boundaries within which these searches should be conducted. On a practical level, the TFL provides a metric for measuring the performance or 'goodness' of new molecules, relative to what is possible. Explorations of large sets of structures within the theory provide insight into new design rules for creating more active molecules. This article is a review of the TFL, starting with a history of its development and its first use to discover that all molecules as of the year 2000 fell a factor of 30 below the limits, and continuing to the present day where the theory continues to provide research opportunities and challenges. The review focuses on off-resonant nonlinear optics in order to sharply focus on the key elements of the TFL, but pointers ...
Ultrasensitive measurement of MEMS cantilever displacement sensitivity below the shot noise limit
Pooser, R C
2014-01-01
The displacement of micro-electro-mechanical-systems(MEMs) cantilevers is used to measure a variety of phenomena in devices ranging from force microscopes for single spin detection[1] to biochemical sensors[2] to uncooled thermal imaging systems[3]. The displacement readout is often performed optically with segmented detectors or interference measurements. Until recently, various noise sources have limited the minimum detectable displacement in MEMs systems, but it is now possible to minimize all other sources[4] so that the noise level of the coherent light field, called the shot noise limit(SNL), becomes the dominant source. Light sources dis- playing quantum-enhanced statistics below this limit are available[5, 6], with applications in gravitational wave astronomy[7] and bioimaging[8], but direct displacement measurements of MEMS cantilevers below the SNL have been impossible until now. Here, we demonstrate the first direct measurement of a MEMs cantilever displacement with sub-SNL sensitivity, thus enabli...
Noise is all around you, from televisions and radios to lawn mowers and washing machines. Normally, you ... sensitive structures of the inner ear and cause noise-induced hearing loss. More than 30 million Americans ...
Spatial noise limited NETD performance of a HgCdTe hybrid focal plane array
Gopal, Vishnu
1996-04-01
This paper presents a model for theoretically estimating the residual spatial noise in a direct injection readout hybrid focal plane array (FPA) consisting of photovoltaic detectors. The procedure consists of computing the response of the pixels after taking into account the nonlinearity induced by the transfer function in the hybrid configuration and the estimated r.m.s. response nonuniformity from the known input parameters of the detector and readout arrays. A linear two point nonuniformity compensation algorithm is applied to the computed pixel responses to calculate the residual spatial noise. Signal-to-spatial noise ratio is then used to estimate the spatial noise limited NETD performance of MWIR and LWIR Hg 1- x Cd x Te hybrid FPAs.
Fundamental limits on the electro-optic device figure of merit
Mossman, Sean; Kuzyk, Mark G
2016-01-01
Device figures of merit are commonly employed to assess bulk material properties for a particular device class, yet these properties ultimately originate in the linear and nonlinear susceptibilities of the material which are not independent of each other. In this work, we calculate the electro-optic device figure of merit based on the half-wave voltage and linear loss, which is important for phase modulators and serves as the simplest example of the approach. This figure of merit is then related back to the microscopic properties in the context of a dye-doped polymer, and its fundamental limits are obtained to provide a target. Surprisingly, the largest figure of merit is not always associated with a large nonlinear-optical response, the quantity that is most often the focus of optimization. An important lesson to materials design is that the figure of merit alone should be optimized. The best device materials can have low nonlinearity provided that the loss is low; or, near resonance high loss may be desirab...
Surface chemistry and fundamental limitations on the plasma cleaning of metals
Dong, Bin; Driver, M. Sky; Emesh, Ismail; Shaviv, Roey; Kelber, Jeffry A.
2016-10-01
In-situ X-ray photoelectron spectroscopy (XPS) studies reveal that plasma cleaning of air-exposed Co or Cu transition metal surfaces results in the formation of a remnant C film 1-3 monolayers thick, which is not reduced upon extensive further plasma exposure. This effect is observed for H2 or NH3 plasma cleaning of Co, and He or NH3 plasma cleaning of Cu, and is observed with both inductively coupled (ICP) and capacitively-coupled plasma (CCP). Changes in C 1 s XPS spectra indicate that this remnant film formation is accompanied by the formation of carbidic C on Co and of graphitic C on Cu. This is in contrast to published work showing no such remnant carbidic/carbon layer after similar treatments of Si oxynitride surfaces. The observation of the remnant carbidic C film on Co and graphitic film on Cu, but not on silicon oxynitride (SiOxNy), regardless of plasma chemistry or type, indicates that this effect is due to plasma induced secondary electron emission from the metal surface, resulting in transformation of sp3 adventitious C to either a metal carbide or graphite. These results suggest fundamental limitations to plasma-based surface cleaning procedures on metal surfaces.
An upper limit to the variation in the fundamental constants at redshift z = 5.2
Levshakov, S A; Boone, F; Agafonova, I I; Reimers, D; Kozlov, M G
2012-01-01
Aims. We constrain a hypothetical variation in the fundamental physical constants over the course of cosmic time. Methods. We use unique observations of the CO(7-6) rotational line and the [CI] 3P_2 - 3P_1 fine-structure line towards a lensed galaxy at redshift z = 5.2 to constrain temporal variations in the constant F = alpha^2/mu, where mu is the electron-to-proton mass ratio and alpha is the fine-structure constant. The relative change in F between z = 0 and z = 5.2, dFF = (F_obs - F_lab)/F_lab, is estimated from the radial velocity offset, dV = V_rot - V_fs, between the rotational transitions in carbon monoxide and the fine-structure transition in atomic carbon. Results. We find a conservative value dV = 1 +/- 5 km/s (1sigma C.L.), which when interpreted in terms of dFF gives dFF < 2x10^-5. Independent methods restrict the mu-variations at the level of dmm < 1x10^-7 at z = 0.7 (look-back time t_z0.7 = 6.4 Gyr). Assuming that temporal variations in mu, if any, are linear, this leads to an upper limit...
Fundamental limitations to tests of the universality of free fall by dropping atoms
Nobili, Anna M
2015-01-01
Tests of the universality of free fall and the weak equivalence principle probe the foundations of General Relativity. Evidence of a violation may lead to the discovery of a new force. The best torsion balance experiments have ruled it out to 10^-13[1]. Cold-atom tests[2-5] have reached 10^-7 and promise to do 7 to 10 orders of magnitude better[6-10] on ground or in space. As mass-dropping experiments[2-4] in a non uniform gravitational field they are sensitive to initial conditions. Errors in the relative position and velocity of the atom clouds at release give rise to a systematic effect which mimics a violation, and these offsets are never measured concurrently with the drop. At the current 10^-7 level they are not an issue. Here we show that when aiming at 2x10^-15 as in[9-10], a fundamental limitation arises. Heisenberg's principle does not allow the centre of mass of free atom clouds to be confined at will in both position and velocity space. The required confinement would be short of the position-momen...
2016-01-01
When blood oxygenation level-dependent (BOLD) contrast functional magnetic resonance imaging (fMRI) was discovered in the early 1990s, it provoked an explosion of interest in exploring human cognition, using brain mapping techniques based on MRI. Standards for data acquisition and analysis were rapidly put in place, in order to assist comparison of results across laboratories. Recently, MRI data acquisition capabilities have improved dramatically, inviting a rethink of strategies for relating functional brain activity at the systems level with its neuronal substrates and functional connections. This paper reviews the established capabilities of BOLD contrast fMRI, the perceived weaknesses of major methods of analysis, and current results that may provide insights into improved brain modelling. These results have inspired the use of in vivo myeloarchitecture for localizing brain activity, individual subject analysis without spatial smoothing and mapping of changes in cerebral blood volume instead of BOLD activation changes. The apparent fundamental limitations of all methods based on nuclear magnetic resonance are also discussed. This article is part of the themed issue ‘Interpreting BOLD: a dialogue between cognitive and cellular neuroscience’. PMID:27574303
Surface chemistry and fundamental limitations on the plasma cleaning of metals
Energy Technology Data Exchange (ETDEWEB)
Dong, Bin, E-mail: bindong@my.unt.edu [Department of Chemistry, University of North Texas, 1155 Union Circle 305070, Denton, TX, 76203 (United States); Driver, M. Sky, E-mail: Marcus.Driver@unt.edu [Department of Chemistry, University of North Texas, 1155 Union Circle 305070, Denton, TX, 76203 (United States); Emesh, Ismail, E-mail: Ismail_Emesh@amat.com [Applied Materials Inc., 3050 Bowers Ave, Santa Clara, CA, 95054 (United States); Shaviv, Roey, E-mail: Roey_Shaviv@amat.com [Applied Materials Inc., 3050 Bowers Ave, Santa Clara, CA, 95054 (United States); Kelber, Jeffry A., E-mail: Jeffry.Kelber@unt.edu [Department of Chemistry, University of North Texas, 1155 Union Circle 305070, Denton, TX, 76203 (United States)
2016-10-30
Highlights: • O{sub 2}-free plasma treatment of air-exposed Co or Cu surfaces yields remnant C layers inert to further plasma cleaning. • The formation of the remnant C layer is graphitic (Cu) or carbidic (Co). • The formation of a remnant C layer is linked to plasma cleaning of a metal surface. - Abstract: In-situ X-ray photoelectron spectroscopy (XPS) studies reveal that plasma cleaning of air-exposed Co or Cu transition metal surfaces results in the formation of a remnant C film 1–3 monolayers thick, which is not reduced upon extensive further plasma exposure. This effect is observed for H{sub 2} or NH{sub 3} plasma cleaning of Co, and He or NH{sub 3} plasma cleaning of Cu, and is observed with both inductively coupled (ICP) and capacitively-coupled plasma (CCP). Changes in C 1 s XPS spectra indicate that this remnant film formation is accompanied by the formation of carbidic C on Co and of graphitic C on Cu. This is in contrast to published work showing no such remnant carbidic/carbon layer after similar treatments of Si oxynitride surfaces. The observation of the remnant carbidic C film on Co and graphitic film on Cu, but not on silicon oxynitride (SiO{sub x}N{sub y}), regardless of plasma chemistry or type, indicates that this effect is due to plasma induced secondary electron emission from the metal surface, resulting in transformation of sp{sup 3} adventitious C to either a metal carbide or graphite. These results suggest fundamental limitations to plasma-based surface cleaning procedures on metal surfaces.
Directory of Open Access Journals (Sweden)
Saeid Amini-Nik
Full Text Available Lasers have in principle the capability to cut at the level of a single cell, the fundamental limit to minimally invasive procedures and restructuring biological tissues. To date, this limit has not been achieved due to collateral damage on the macroscale that arises from thermal and shock wave induced collateral damage of surrounding tissue. Here, we report on a novel concept using a specifically designed Picosecond IR Laser (PIRL that selectively energizes water molecules in the tissue to drive ablation or cutting process faster than thermal exchange of energy and shock wave propagation, without plasma formation or ionizing radiation effects. The targeted laser process imparts the least amount of energy in the remaining tissue without any of the deleterious photochemical or photothermal effects that accompanies other laser wavelengths and pulse parameters. Full thickness incisional and excisional wounds were generated in CD1 mice using the Picosecond IR Laser, a conventional surgical laser (DELight Er:YAG or mechanical surgical tools. Transmission and scanning electron microscopy showed that the PIRL laser produced minimal tissue ablation with less damage of surrounding tissues than wounds formed using the other modalities. The width of scars formed by wounds made by the PIRL laser were half that of the scars produced using either a conventional surgical laser or a scalpel. Aniline blue staining showed higher levels of collagen in the early stage of the wounds produced using the PIRL laser, suggesting that these wounds mature faster. There were more viable cells extracted from skin using the PIRL laser, suggesting less cellular damage. β-catenin and TGF-β signalling, which are activated during the proliferative phase of wound healing, and whose level of activation correlates with the size of wounds was lower in wounds generated by the PIRL system. Wounds created with the PIRL systsem also showed a lower rate of cell proliferation. Direct
Amini-Nik, Saeid; Kraemer, Darren; Cowan, Michael L; Gunaratne, Keith; Nadesan, Puviindran; Alman, Benjamin A; Miller, R J Dwayne
2010-09-28
Lasers have in principle the capability to cut at the level of a single cell, the fundamental limit to minimally invasive procedures and restructuring biological tissues. To date, this limit has not been achieved due to collateral damage on the macroscale that arises from thermal and shock wave induced collateral damage of surrounding tissue. Here, we report on a novel concept using a specifically designed Picosecond IR Laser (PIRL) that selectively energizes water molecules in the tissue to drive ablation or cutting process faster than thermal exchange of energy and shock wave propagation, without plasma formation or ionizing radiation effects. The targeted laser process imparts the least amount of energy in the remaining tissue without any of the deleterious photochemical or photothermal effects that accompanies other laser wavelengths and pulse parameters. Full thickness incisional and excisional wounds were generated in CD1 mice using the Picosecond IR Laser, a conventional surgical laser (DELight Er:YAG) or mechanical surgical tools. Transmission and scanning electron microscopy showed that the PIRL laser produced minimal tissue ablation with less damage of surrounding tissues than wounds formed using the other modalities. The width of scars formed by wounds made by the PIRL laser were half that of the scars produced using either a conventional surgical laser or a scalpel. Aniline blue staining showed higher levels of collagen in the early stage of the wounds produced using the PIRL laser, suggesting that these wounds mature faster. There were more viable cells extracted from skin using the PIRL laser, suggesting less cellular damage. β-catenin and TGF-β signalling, which are activated during the proliferative phase of wound healing, and whose level of activation correlates with the size of wounds was lower in wounds generated by the PIRL system. Wounds created with the PIRL systsem also showed a lower rate of cell proliferation. Direct comparison of wound
Heat-Assisted Magnetic Recording: Fundamental Limits to Inverse Electromagnetic Design
Bhargava, Samarth
In this dissertation, we address the burgeoning fields of diffractive optics, metals-optics and plasmonics, and computational inverse problems in the engineering design of electromagnetic structures. We focus on the application of the optical nano-focusing system that will enable Heat-Assisted Magnetic Recording (HAMR), a higher density magnetic recording technology that will fulfill the exploding worldwide demand of digital data storage. The heart of HAMR is a system that focuses light to a nano- sub-diffraction-limit spot with an extremely high power density via an optical antenna. We approach this engineering problem by first discussing the fundamental limits of nano-focusing and the material limits for metal-optics and plasmonics. Then, we use efficient gradient-based optimization algorithms to computationally design shapes of 3D nanostructures that outperform human designs on the basis of mass-market product requirements. In 2014, the world manufactured ˜1 zettabyte (ZB), ie. 1 Billion terabytes (TBs), of data storage devices, including ˜560 million magnetic hard disk drives (HDDs). Global demand of storage will likely increase by 10x in the next 5-10 years, and manufacturing capacity cannot keep up with demand alone. We discuss the state-of-art HDD and why industry invented Heat-Assisted Magnetic Recording (HAMR) to overcome the data density limitations. HAMR leverages the temperature sensitivity of magnets, in which the coercivity suddenly and non-linearly falls at the Curie temperature. Data recording to high-density hard disks can be achieved by locally heating one bit of information while co-applying a magnetic field. The heating can be achieved by focusing 100 microW of light to a 30nm diameter spot on the hard disk. This is an enormous light intensity, roughly ˜100,000,000x the intensity of sunlight on the earth's surface! This power density is ˜1,000x the output of gold-coated tapered optical fibers used in Near-field Scanning Optical Microscopes
Noise in space-charge-limited current in a CdS-single crystal at low injection level
Driedonks, F.
1967-01-01
Current noise spectra (25Hz–20MHz) of a CdS-diode, working under space-charge-limited conditions. show trapping noise at low frequencies and slightly suppressed noise in the upper frequency range. Suppression is relatively small due to the effect of traps.
Coherence Times of Bose-Einstein Condensates beyond the Shot-Noise Limit via Superfluid Shielding
Burton, William Cody; Chung, Woo Chang; Vadia, Samarth; Chen, Wenlan; Ketterle, Wolfgang
2016-01-01
We demonstrate a new way to extend the coherence time of separated Bose-Einstein condensates that involves immersion into a superfluid bath. When both the system and the bath have similar scattering lengths, immersion in a superfluid bath cancels out inhomogeneous potentials either imposed by external fields or inherent in density fluctuations due to atomic shot noise. This effect, which we call superfluid shielding, allows for coherence lifetimes beyond the projection noise limit. We probe the coherence between separated condensates in different sites of an optical lattice by monitoring the contrast and decay of Bloch oscillations. Our technique demonstrates a new way that interactions can improve the performance of quantum devices.
Quantum plasmonic sensing: beyond the shot-noise and diffraction limit
Lee, Changhyoup; Lee, Jinhyoung; Rockstuhl, Carsten; Maier, Stefan A; Tame, Mark
2016-01-01
Photonic sensors have many applications in a range of physical settings, from measuring mechanical pressure in manufacturing to detecting protein concentration in biomedical samples. A variety of sensing approaches exist, and plasmonic systems in particular have received much attention due to their ability to confine light below the diffraction limit, greatly enhancing sensitivity. Recently, quantum techniques have been identified that can outperform classical sensing methods and achieve sensitivity below the so-called shot-noise limit. Despite this significant potential, the use of quantum techniques in plasmonic systems for further improving sensing capabilities is not well understood. Here, we study the sensing performance of a plasmonic interferometer that simultaneously exploits the quantum nature of light and its electromagnetic field confinement. We show that, despite the presence of loss, specialised quantum resources can provide improved sensitivity and resolution beyond the shot-noise limit within a...
Radio-frequency Electrometry Using Rydberg Atoms in Vapor Cells: Towards the Shot Noise Limit
Kumar, Santosh; Fan, Haoquan; Jahangiri, Akbar; Kuebler, Harald; Shaffer, James P.; 5. Physikalisches Institut, Universitat Stuttgart, Germany Collaboration
2016-05-01
Rydberg atoms are a promising candidate for radio frequency (RF) electric field sensing. Our method uses electromagnetically induced transparency with Rydberg atoms in vapor cells to read out the effect that the RF electric field has on the Rydberg atoms. The method has the potential for high sensitivity (pV cm-1 Hz- 1 / 2) and can be self-calibrated. Some of the main factors limiting the sensitivity of RF electric field sensing from reaching the shot noise limit are the residual Doppler effect and the sensitivity of the optical read-out using the probe laser. We present progress on overcoming the residual Doppler effect by using a new multi-photon scheme and reaching the shot noise detection limit using frequency modulated spectroscopy. Our experiments also show promise for studying quantum optical effects such as superradiance in vapor cells using Rydberg atoms. This work is supported by DARPA, ARO, and NRO.
Spatial resolution limits for the localization of noise sources using direct sound mapping
Fernandez Comesaña, D.; Holland, K. R.; Fernandez-Grande, E.
2016-08-01
One of the main challenges arising from noise and vibration problems is how to identify the areas of a device, machine or structure that produce significant acoustic excitation, i.e. the localization of main noise sources. The direct visualization of sound, in particular sound intensity, has extensively been used for many years to locate sound sources. However, it is not yet well defined when two sources should be regarded as resolved by means of direct sound mapping. This paper derives the limits of the direct representation of sound pressure, particle velocity and sound intensity by exploring the relationship between spatial resolution, noise level and geometry. The proposed expressions are validated via simulations and experiments. It is shown that particle velocity mapping yields better results for identifying closely spaced sound sources than sound pressure or sound intensity, especially in the acoustic near-field.
Shangguan, Wen-Bin; Liu, Xiao-Ang; Lv, Zhao-Ping; Rakheja, Subhash
2016-08-01
The design logic and calculation method for determining mount stiffness and damping for a Powertrain Mounting System (PMS) based on reductions of vehicle vibration and noise contributed by mounts is proposed in this paper. Firstly, the design target for a PMS with regard to vibration and noise limitations of vehicle level contributed form mounts is described. Then a vehicle model with 13 Degree of Freedoms (DOFs) is proposed, which includes 6DOFs for the powertrain, 3 DOFs for the car body and 4DOFs for the four unsprung mass, and the dynamic equation for the model is derived. Some widely used models, such as the 6 DOFs model of the powertrain for the design calculation of a PMS, the 7 DOFs model (Body's 3 DOFs; unsprung mass's 4 DOFs) and the 9 DOFs model (powertrain's 6 DOFs; Body's 3 DOFs) for ride analysis of a vehicle, are the specific cases of the presented model of 13 DOF. Thirdly, the calculation method for obtaining the vibration of seat track and evaluation point and the noise at driver right ear is presented based on the mount forces and the vibration and noise transfer functions. An optimization process is proposed to get the mount stiffness and damping based on minimization of vehicle vibration and noise, and the optimized stiffness is validated by comparing the calculated vibration and noise and limitations. In the end of this paper, the natural frequencies and mode energies for the powertrain, the body and the unsprung mass are calculated using different models and the results are compared and analyzed.
Averaging, not internal noise, limits the development of coherent motion processing
Directory of Open Access Journals (Sweden)
Catherine Manning
2014-10-01
Full Text Available The development of motion processing is a critical part of visual development, allowing children to interact with moving objects and navigate within a dynamic environment. However, global motion processing, which requires pooling motion information across space, develops late, reaching adult-like levels only by mid-to-late childhood. The reasons underlying this protracted development are not yet fully understood. In this study, we sought to determine whether the development of motion coherence sensitivity is limited by internal noise (i.e., imprecision in estimating the directions of individual elements and/or global pooling across local estimates. To this end, we presented equivalent noise direction discrimination tasks and motion coherence tasks at both slow (1.5°/s and fast (6°/s speeds to children aged 5, 7, 9 and 11 years, and adults. We show that, as children get older, their levels of internal noise reduce, and they are able to average across more local motion estimates. Regression analyses indicated, however, that age-related improvements in coherent motion perception are driven solely by improvements in averaging and not by reductions in internal noise. Our results suggest that the development of coherent motion sensitivity is primarily limited by developmental changes within brain regions involved in integrating motion signals (e.g., MT/V5.
DEFF Research Database (Denmark)
Nielsen, Mads Lønstrup; Mørk, Jesper; Suzuki, R.
2005-01-01
We identify a fundamental difference between the ASE noise filtering properties of different all-optical SOA-based switch configurations, and divide the switches into two classes. An in-band ASE suppression ratio quantifying the difference is derived theoretically and the impact of the ASE filter...... filtering on the optical spectrum is verified experimentally using a hybrid DISC setup. ASE power suppression of around 3 dB over the total signal bandwidth is demonstrated.......We identify a fundamental difference between the ASE noise filtering properties of different all-optical SOA-based switch configurations, and divide the switches into two classes. An in-band ASE suppression ratio quantifying the difference is derived theoretically and the impact of the ASE...
Harlow, Jennifer; Teufel, John; Donner, Tobias; Castellanos-Beltran, Manuel; Lehnert, Konrad
2010-03-01
Observing quantum behavior of mechanical motion is challenging because it is difficult both to prepare pure quantum states of motion and to detect those states with sufficient precision. We present displacement measurements of a nanomechanical oscillator with an imprecision below that at the standard quantum limit [1]. We infer the motion from the phase modulation imprinted on a microwave signal by that motion. The modulation is enhanced by embedding the oscillator in a high-Q microwave cavity. We achieve the low imprecision by reading out the modulation with a Josephson Parametric Amplifier, realizing a microwave interferometer that operates near the shot-noise limit. The apparent motion of the mechanical oscillator due the interferometer's noise is now substantially less than its zero-point motion, making future detection of quantum states feasible. In addition, the phase sensitivity of the demonstrated interferometer is 30 times higher than previous microwave interferometers, providing a critical piece of technology for many experiments investigating quantum information encoded in microwave fields. [1] J. D. Teufel, T. Donner, M. A. Castellanos-Beltran, J. W. Harlow, K. W. Lehnert, Nature Nanotechnology, doi:10.1038/nnano.2009.343, (2009).
Ma, Jiaju; Zhang, Yang; Wang, Xiaoxin; Ying, Lei; Masoodian, Saleh; Wang, Zhiyuan; Starkey, Dakota A.; Deng, Wei; Kumar, Rahul; Wu, Yang; Ghetmiri, Seyed Amir; Yu, Zongfu; Yu, Shui-Qing; Salamo, Gregory J.; Fossum, Eric R.; Liu, Jifeng
2017-05-01
This research investigates the fundamental limits and trade-space of quantum semiconductor photodetectors using the Schrödinger equation and the laws of thermodynamics.We envision that, to optimize the metrics of single photon detection, it is critical to maximize the optical absorption in the minimal volume and minimize the carrier transit process simultaneously. Integration of photon management with quantum charge transport/redistribution upon optical excitation can be engineered to maximize the quantum efficiency (QE) and data rate and minimize timing jitter at the same time. Due to the ultra-low capacitance of these quantum devices, even a single photoelectron transfer can induce a notable change in the voltage, enabling non-avalanche single photon detection at room temperature as has been recently demonstrated in Si quanta image sensors (QIS). In this research, uniform III-V quantum dots (QDs) and Si QIS are used as model systems to test the theory experimentally. Based on the fundamental understanding, we also propose proof-of-concept, photon-managed quantum capacitance photodetectors. Built upon the concepts of QIS and single electron transistor (SET), this novel device structure provides a model system to synergistically test the fundamental limits and tradespace predicted by the theory for semiconductor detectors. This project is sponsored under DARPA/ARO's DETECT Program: Fundamental Limits of Quantum Semiconductor Photodetectors.
Weak-noise limit of a piecewise-smooth stochastic differential equation.
Chen, Yaming; Baule, Adrian; Touchette, Hugo; Just, Wolfram
2013-11-01
We investigate the validity and accuracy of weak-noise (saddle-point or instanton) approximations for piecewise-smooth stochastic differential equations (SDEs), taking as an illustrative example a piecewise-constant SDE, which serves as a simple model of Brownian motion with solid friction. For this model, we show that the weak-noise approximation of the path integral correctly reproduces the known propagator of the SDE at lowest order in the noise power, as well as the main features of the exact propagator with higher-order corrections, provided the singularity of the path integral associated with the nonsmooth SDE is treated with some heuristics. We also show that, as in the case of smooth SDEs, the deterministic paths of the noiseless system correctly describe the behavior of the nonsmooth SDE in the low-noise limit. Finally, we consider a smooth regularization of the piecewise-constant SDE and study to what extent this regularization can rectify some of the problems encountered when dealing with discontinuous drifts and singularities in SDEs.
Li, Liwei; Bryant, Doug; van Heugten, Tony; Bos, Philip J
2013-03-20
A comprehensive analysis of fundamental factors and their effects on the performance of liquid crystal (LC)-based lenses is given. The analysis adopts numerical LC director and electric field simulation, as well as scalar diffraction theory for calculating the lens performance considering different variable factors. A high-efficiency LC lens with concentric electrode rings is fabricated for verifying and enriching the analysis. The measurement results are in close agreement with the analysis, and a summary of key factors is given with their quantitative contributions to the efficiency.
Quantum limited noise figure operation of high gain erbium doped fiber amplifiers
DEFF Research Database (Denmark)
Lumholt, Ole; Povlsen, Jørn Hedegaard; Schüsler, Kim;
1993-01-01
powers below -5 dBm, and an improvement of 2.0 dB with a simultaneous gain increase of 4.1 dB is measured relative to a gain-optimized fiber. The optimum isolator location is evaluated for different pump and signal wavelengths in both an Al/Er-doped and a Ge/Er-doped fiber, for pump and signal power......Performance improvements obtained by using an isolator as an amplified-spontaneous-emission-suppressing component within erbium-doped fibers are evaluated. Simultaneous high-gain and near-quantum-limited noise figures can be obtained by such a scheme. The noise figure improves for input signal...... variations and different pump configurations. In all cases the optimum isolator position lies within 10-37% of the total fiber length for small signal operation...
Shot-noise-limited magnetometer with sub-picotesla sensitivity at room temperature.
Lucivero, Vito Giovanni; Anielski, Pawel; Gawlik, Wojciech; Mitchell, Morgan W
2014-11-01
We report a photon shot-noise-limited (SNL) optical magnetometer based on amplitude modulated optical rotation using a room-temperature (85)Rb vapor in a cell with anti-relaxation coating. The instrument achieves a room-temperature sensitivity of 70 fT / √Hz at 7.6 μT. Experimental scaling of noise with optical power, in agreement with theoretical predictions, confirms the SNL behaviour from 5 μT to 75 μT. The combination of best-in-class sensitivity and SNL operation makes the system a promising candidate for application of squeezed light to a state-of-the-art atomic sensor.
Fundamental Limits of Parallel Optical Wireless Channels: Capacity Results and Outage Formulation
Chaaban, Anas
2016-10-26
Multi-channel (MC) optical wireless communication (OWC) systems employing wave-division multiplexing for outdoors free-space optical communications, or multi-user timedivision multiple access for indoors visible-light communications, e.g., can be modeled as parallel channels. Multi-input multioutput OWC systems can also be transformed, possibly with some performance loss, to parallel channels using pre-/postcoding. Studying the performance of such MC-OWC systems requires characterizing the capacity of the underlying parallel channels. In this paper, upper and lower bounds on the capacity of constant parallel OWC channels with a total average intensity constraint are derived. Then, the paper focuses on finding intensity allocations that maximize the lower bounds given channel-state information at the transmitter (CSIT). Due to its nonconvexity, the KKT conditions are used to describe a list of candidate allocations. Instead searching exhaustively for the best solution, low-complexity near-optimal algorithms are proposed. The resulting optimized lower bound nearly coincides with capacity at high signal-to-noise ratio (SNR). Under a quasi-static channel model and in the absence of CSIT, outage probability upper and lower bounds are derived. Those bounds also meet at high SNR, thus characterizing the outage capacity in this regime. Finally, the results are extended to a system with both average and peak intensity constraints.
Energy Technology Data Exchange (ETDEWEB)
McGraw R.; Wang, J.; Kuang, C.
2012-04-26
We examine the nucleated (with barrier) activation of perfectly wetting (zero contact angle) particles ranging from essentially bulk size down to approximately 1-nm mass diameter. While similar studies trace back to the pioneering work of Fletcher, we present here a novel approach to the analysis based on general area constructions that enable key thermodynamic properties, including surface and bulk contributions to nucleation work, to be interpreted geometrically with reference to the Kelvin curve. The kinetics of activation are described in more detail in terms of the mean first passage time (MFPT) for barrier crossing. MFPT theory and benchmark calculations are used to develop and test a new approximate-but-simpler-to-use analytic expression for the barrier crossing rate. The present study is motivated by recent condensation particle counter (CPC) studies that appear to finally establish the long-predicted detection of 'sub-Kelvin' particles in the nano-size regime. Corresponding states thermodynamic and kinetic scaling approaches are used to facilitate the correlation and selection of optimal CPC working fluids and operating conditions based on a new metric for heterogeneous nucleation, the signal-to-noise ratio, and physical and chemical properties.
Room Temperature Operation of a Radiofrequency Diamond Magnetometer near the Shot Noise Limit
Shin, Chang S; Butler, Mark C; Trease, David R; Seltzer, Scott J; Mustonen, J Peter; Kennedy, Daniel J; Acosta, Victor M; Budker, Dmitry; Pines, Alexander; Bajaj, Vikram S
2012-01-01
We operate a nitrogen vacancy (NV-) diamond magnetometer at ambient temperatures and study the dependence of its bandwidth on experimental parameters including optical and microwave excitation powers. We introduce an analytical theory that yields an explicit formula for the response of an ensemble of NV- spins to an oscillating magnetic field, such as in NMR applications. We measure a detection bandwidth of 1.6 MHz and a sensitivity of 4.6 nT/Hz^(1/2), unprecedented in a detector with this active volume and close to the photon shot noise limit of our experiment.
Limit theorems for power variations of ambit field driven by white noise
DEFF Research Database (Denmark)
Pakkanen, Mikko S.
2014-01-01
We study the asymptotics of lattice power variations of two-parameter ambit fields driven by white noise. Our first result is a law of large numbers for power variations. Under a constraint on the memory of the ambit field, normalized power variations converge to certain integral functionals...... of the volatility field associated to the ambit field, when the lattice spacing tends to zero. This result holds also for thinned power variations that are computed by only including increments that are separated by gaps with a particular asymptotic behavior. Our second result is a stable central limit theorem...
Phase noise in pulsed Doppler lidar and limitations on achievable single-shot velocity accuracy
Mcnicholl, P.; Alejandro, S.
1992-01-01
The smaller sampling volumes afforded by Doppler lidars compared to radars allows for spatial resolutions at and below some sheer and turbulence wind structure scale sizes. This has brought new emphasis on achieving the optimum product of wind velocity and range resolutions. Several recent studies have considered the effects of amplitude noise, reduction algorithms, and possible hardware related signal artifacts on obtainable velocity accuracy. We discuss here the limitation on this accuracy resulting from the incoherent nature and finite temporal extent of backscatter from aerosols. For a lidar return from a hard (or slab) target, the phase of the intermediate frequency (IF) signal is random and the total return energy fluctuates from shot to shot due to speckle; however, the offset from the transmitted frequency is determinable with an accuracy subject only to instrumental effects and the signal to noise ratio (SNR), the noise being determined by the LO power in the shot noise limited regime. This is not the case for a return from a media extending over a range on the order of or greater than the spatial extent of the transmitted pulse, such as from atmospheric aerosols. In this case, the phase of the IF signal will exhibit a temporal random walk like behavior. It will be uncorrelated over times greater than the pulse duration as the transmitted pulse samples non-overlapping volumes of scattering centers. Frequency analysis of the IF signal in a window similar to the transmitted pulse envelope will therefore show shot-to-shot frequency deviations on the order of the inverse pulse duration reflecting the random phase rate variations. Like speckle, these deviations arise from the incoherent nature of the scattering process and diminish if the IF signal is averaged over times greater than a single range resolution cell (here the pulse duration). Apart from limiting the high SNR performance of a Doppler lidar, this shot-to-shot variance in velocity estimates has a
Lubrication-related residue as a fundamental process scaling limit to gravure printed electronics.
Kitsomboonloha, Rungrot; Subramanian, Vivek
2014-04-01
In gravure printing, excess ink is removed from a patterned plate or roll by wiping with a doctor blade, leaving a thin lubrication film in the nonpatterned area. Reduction of this lubrication film is critical for gravure printing of electronics, since the resulting residue can lower device performance or even catastrophically impact circuit yield. We report on experiments and quantitative analysis of lubrication films in a highly scaled gravure printing process. We investigate the effects of ink viscosity, wiping speed, loading force, blade stiffness and blade angle on the lubrication film, and further, use the resulting data to investigate the relevant lubrication regimes associated with wiping during gravure printing. Based on this analysis, we are able to posit the lubrication regime associated with wiping during gravure printing, provide insight into the ultimate limits of residue reduction, and, furthermore, are able to provide process guidelines and design rules to achieve these limits.
Physical Mechanism and Fundamental Performance Limits on Graphene Non-Volatile Memory Technologies
Song, Emil Beom
2012-01-01
Non–volatile memory (NVM) constitutes a vital portion in electronics to retain information for both archiving and data processing. Limitations encountered in flash technology upon increasing density and reducing cost by scaling necessitates alternative memory structures beyond complementary–metal–oxide–semiconductor (CMOS). The single atomic two–dimensional profile and the superior physical properties of graphene allow advancements in a variety of memory metrics ...
Athans, M.; Ku, R.; Gershwin, S. B.
1977-01-01
This note shows that the optimal control of dynamic systems with uncertain parameters has certain limitations. In particular, by means of a simple scalar linear-quadratic optimal control example, it is shown that the infinite horizon solution does not exist if the parameter uncertainty exceeds a certain quantifiable threshold; we call this the uncertainty threshold principle. The philosophical and design implications of this result are discussed.
Kroupa, P; Kroupa, Pavel; Weidner, Carsten
2005-01-01
Theoretical considerations lead to the expectation that stars should not have masses larger than about m_{max*}=60-120Msun, while the observational evidence has been ambiguous. Only very recently has a physical stellar mass limit near 150Msun emerged thanks to modern high-resolution observations of local star-burst clusters. But this limit does not appear to depend on metallicity, in contradiction to theory. Important uncertainties remain though. It is now also emerging that star-clusters limit the masses of their constituent stars, such that a well-defined relation between the mass of the most massive star in a cluster and the cluster mass, m_{max}=F(M_ecl) \\le m_{max*}\\approx 150Msun, exists. One rather startling finding is that the observational data strongly favour clusters being built-up by consecutively forming more-massive stars until the most massive stars terminate further star-formation. The relation also implies that composite populations, which consist of many star clusters, most of which may be d...
Double-pass high-gain low-noise EDFA over S- and C+L-bands by tunable fundamental-mode leakage loss.
Hung, Chi-Ming; Chen, Nan-Kuang; Lai, Yinchieh; Chi, Sien
2007-02-19
We demonstrate a high-gain low-noise double-pass tunable EDFA over S- and C+L-bands by discretely introducing fundamental-mode leakage loss in a 16-m-long standard C-band Er(3+)-doped fiber. The amplified spontaneous emission at the wavelengths of longer than 1530 nm can be substantially attenuated by the ASE suppressing filters to maintain high population inversion and to squeeze out the optical gain for S-band signals. When the filters are disabled, the gain bandwidth immediately returns back to the C+L-bands. Under S-band operation, a 37 dB small signal gain and a minimum 4.84 dB noise figure at 1486.9 nm are achieved with a 980 nm pump power of 154 mW.
DEFF Research Database (Denmark)
Bouserhal, Rachel E.; MacDonald, Ewen; Falk, Tiago H.;
2016-01-01
concern for people wearing hearing protection devices (HPD). Although practical, radio communication is cumbersome, as it does not distinguish designated receivers. A smarter radio communication protocol must be developed to alleviate this problem. Thus, it is necessary to model speech production in noise...... while wearing HPDs. Such a model opens the door to radio communication systems that distinguish receivers and offer more efficient communication between persons wearing HPDs. Design: This paper presents the results of a pilot study aimed to investigate the effects of occluding the ear on changes...... in voice level and fundamental frequency in noise and with varying talker-to-listener distance. Study sample: Twelve participants with a mean age of 28 participated in this study. Results: Compared to existing data, results show a trend similar to the open ear condition with the exception of the occluded...
Quantum Metrology: Surpassing the shot-noise limit with Dzyaloshinskii-Moriya interaction.
Ozaydin, Fatih; Altintas, Azmi Ali
2015-11-09
Entanglement is at the heart of quantum technologies such as quantum information and quantum metrology. Providing larger quantum Fisher information (QFI), entangled systems can be better resources than separable systems in quantum metrology. However the effects on the entanglement dynamics such as decoherence usually decrease the QFI considerably. On the other hand, Dzyaloshinskii-Moriya (DM) interaction has been shown to excite entanglement. Since an increase in entanglement does not imply an increase in QFI, and also there are cases where QFI decreases as entanglement increases, it is interesting to study the influence of DM interaction on quantum metrology. In this work, we study the QFI of thermal entanglement of two-qubit and three-qubit Heisenberg models with respect to SU(2) rotations. We show that even at high temperatures, DM interaction excites QFI of both ferromagnetic and antiferromagnetic models. We also show that QFI of the ferromagnetic model of two qubits can surpass the shot-noise limit of the separable states, while QFI of the antiferromagnetic model in consideration can only approach to the shot-noise limit. Our results open new insights in quantum metrology with Heisenberg models.
Limit theorems for power variations of ambit fields driven by white noise
DEFF Research Database (Denmark)
Pakkanen, Mikko
We study the asymptotic behavior of lattice power variations of two-parameter ambit fields that are driven by white noise. Our first result is a law of large numbers for such power variations. Under a constraint on the memory of the ambit field, normalized power variations are shown to converge...... to certain integral functionals of the volatility field associated to the ambit field, when the lattice spacing tends to zero. This law of large numbers holds also for thinned power variations that are computed by only including increments that are separated by gaps with a particular asympotic behavior. Our...... second result is a related stable central limit theorem for thinned power variations. Additionally, we provide concrete examples of ambit fields that satisfy the assumptions of our limit theorems....
Fundamental High-Speed Limits in Single-Molecule, Single-Cell, and Nanoscale Force Spectroscopies
2016-01-01
Force spectroscopy is enhancing our understanding of single-biomolecule, single-cell, and nanoscale mechanics. Force spectroscopy postulates the proportionality between the interaction force and the instantaneous probe deflection. By studying the probe dynamics, we demonstrate that the total force acting on the probe has three different components: the interaction, the hydrodynamic, and the inertial. The amplitudes of those components depend on the ratio between the resonant frequency and the frequency at which the data are measured. A force–distance curve provides a faithful measurement of the interaction force between two molecules when the inertial and hydrodynamic components are negligible. Otherwise, force spectroscopy measurements will underestimate the value of unbinding forces. Neglecting the above force components requires the use of frequency ratios in the 50–500 range. These ratios will limit the use of high-speed methods in force spectroscopy. The theory is supported by numerical simulations. PMID:27359243
Fundamental limits and near-optimal design of graphene modulators and non-reciprocal devices
Tamagnone, Michele; Mosig, Juan R; Perruisseau-Carrier, Julien
2013-01-01
The potential of graphene for use in photonic applications was evidenced by recent demonstrations of modulators, polarisation rotators, and isolators. These promising yet preliminary results raise crucial questions: what is the optimal performance achievable by more complex designs using multilayer structures, graphene patterning, metal additions, or a combination of these approaches, and how can this optimum design be achieved in practice? Today, the complexity of the problem, which is magnified by the variability in graphene parameters, leaves the design of these new devices to time-consuming and suboptimal trial-and-error procedures. We address this issue by first demonstrating that the relevant figures of merit for the devices above are subject to absolute theoretical upper bounds. Strikingly these limits are related only to the conductivity tensor of graphene; thus, we can provide essential roadmap information such as the best possible device performance versus wavelength and graphene quality. Second, ba...
DEFF Research Database (Denmark)
Iles-Smith, Jake; McCutcheon, Dara; Mørk, Jesper
2016-01-01
The desire to produce high-quality single photons for applications in quantum information science has lead to renewed interest in exploring solid-state emitters in the weak excitation regime. Under these conditions it is expected that photons are coherently scattered, and so benefit from...... find that the sideband resulting from non-Markovian relaxation of the phonon environment leads to a fundamental limit to the fraction of coherently scattered light and to the visibility of two-photon coalescence at weak driving, both of which are absent for atomic systems or within simpler Markovian...
Fundamental limits on wavelength, efficiency and yield of the charge separation triad.
Directory of Open Access Journals (Sweden)
Alexander Punnoose
Full Text Available In an attempt to optimize a high yield, high efficiency artificial photosynthetic protein we have discovered unique energy and spatial architecture limits which apply to all light-activated photosynthetic systems. We have generated an analytical solution for the time behavior of the core three cofactor charge separation element in photosynthesis, the photosynthetic cofactor triad, and explored the functional consequences of its makeup including its architecture, the reduction potentials of its components, and the absorption energy of the light absorbing primary-donor cofactor. Our primary findings are two: First, that a high efficiency, high yield triad will have an absorption frequency more than twice the reorganization energy of the first electron transfer, and second, that the relative distance of the acceptor and the donor from the primary-donor plays an important role in determining the yields, with the highest efficiency, highest yield architecture having the light absorbing cofactor closest to the acceptor. Surprisingly, despite the increased complexity found in natural solar energy conversion proteins, we find that the construction of this central triad in natural systems matches these predictions. Our analysis thus not only suggests explanations for some aspects of the makeup of natural photosynthetic systems, it also provides specific design criteria necessary to create high efficiency, high yield artificial protein-based triads.
Controlled longitudinal emittance blow-up using band-limited phase noise in CERN PSB
Quartullo, D.; Shaposhnikova, E.; Timko, H.
2017-07-01
Controlled longitudinal emittance blow-up (from 1 eVs to 1.4 eVs) for LHC beams in the CERN PS Booster is currently achievied using sinusoidal phase modulation of a dedicated high-harmonic RF system. In 2021, after the LHC injectors upgrade, 3 eVs should be extracted to the PS. Even if the current method may satisfy the new requirements, it relies on low-power level RF improvements. In this paper another method of blow-up was considered, that is the injection of band-limited phase noise in the main RF system (h=1), never tried in PSB but already used in CERN SPS and LHC, under different conditions (longer cycles). This technique, which lowers the peak line density and therefore the impact of intensity effects in the PSB and the PS, can also be complementary to the present method. The longitudinal space charge, dominant in the PSB, causes significant synchrotron frequency shifts with intensity, and its effect should be taken into account. Another complication arises from the interaction of the phase loop with the injected noise, since both act on the RF phase. All these elements were studied in simulations of the PSB cycle with the BLonD code, and the required blow-up was achieved.
Shot-noise-limited spin measurements in a pulsed molecular beam
Kirilov, E; Doyle, J M; Gabrielse, G; Gurevich, Y V; Hess, P W; Hutzler, N R; O'Leary, B R; Petrik, E; Spaun, B; Vutha, A C; DeMille, D
2013-01-01
Heavy diatomic molecules have been identified as good candidates for use in electron electric dipole moment (eEDM) searches. Suitable molecular species can be produced in pulsed beams, but with a total flux and/or temporal evolution that varies significantly from pulse to pulse. These variations can degrade the experimental sensitivity to changes in spin precession phase of an electri- cally polarized state, which is the observable of interest for an eEDM measurement. We present two methods for measurement of the phase that provide immunity to beam temporal variations, and make it possible to reach shot-noise-limited sensitivity. Each method employs rapid projection of the spin state onto both components of an orthonormal basis. We demonstrate both methods using the eEDM-sensitive H state of thorium monoxide (ThO), and use one of them to measure the magnetic moment of this state with increased accuracy relative to previous determinations.
Bouserhal, Rachel E; Macdonald, Ewen N; Falk, Tiago H; Voix, Jérémie
2016-01-01
Speech production in noise with varying talker-to-listener distance has been well studied for the open ear condition. However, occluding the ear canal can affect the auditory feedback and cause deviations from the models presented for the open-ear condition. Communication is a main concern for people wearing hearing protection devices (HPD). Although practical, radio communication is cumbersome, as it does not distinguish designated receivers. A smarter radio communication protocol must be developed to alleviate this problem. Thus, it is necessary to model speech production in noise while wearing HPDs. Such a model opens the door to radio communication systems that distinguish receivers and offer more efficient communication between persons wearing HPDs. This paper presents the results of a pilot study aimed to investigate the effects of occluding the ear on changes in voice level and fundamental frequency in noise and with varying talker-to-listener distance. Twelve participants with a mean age of 28 participated in this study. Compared to existing data, results show a trend similar to the open ear condition with the exception of the occluded quiet condition. This implies that a model can be developed to better understand speech production for the occluded ear.
Quantum Noise Limits in White-Light-Cavity-Enhanced Gravitational Wave Detectors
Zhou, Minchuan; Shahriar, Selim M
2014-01-01
Previously, we had proposed a gravitational wave detector that incorporates the white light cavity (WLC) effect using a compound cavity for signal recycling (CC-SR). Here, we first calculate the quantum noise (QN) limited sensitivity curves for this design, and find that the broadening of sensitivity predicted by the classical analysis is also present in these curves, but is somewhat reduced. Furthermore, we find that the curves always stay above the standard quantum limit (SQL). To circumvent this limitation, we modify the dispersion to compensate the non-linear phase variation produced by the opto-mechanical (OM) resonance effects by making use of the single sideband approximation (SSA). We find that the resonance dips in the resulting QN curves entails a 14 times higher sensitivity-bandwidth product compared to the highest sensitivity result presented by Bunanno and Chen. We also present a simpler scheme (WLC-SR) where a dispersion medium is inserted in the SR cavity. Compared to the highest sensitivity re...
Pueyo, Laurent; Norman, Colin Arthur; Soummer, Remi; Perrin, Marshall D.; N'Diaye, Mamadou; Choquet, Elodie
2015-01-01
In a recent paper we discussed a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach, named Active Compensation of Aperture Discontinuities (ACAD) relies on two sequential Deformable Mirrors to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and/or segment gaps. In this configuration the parameter landscape of Deformable Mirror Surfaces that yield high contrast Point Spread Functions is not linear, and non-linear methods are needed to find the true minimum. In particular we showed that broadband high contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies for a variety of telescope pupil geometries. In this paper we first focus on the fundamental limits and practical trade-offs associated with ACAD. In a first part we will study the fundamental limits and practical tradeoffs associated with ACAD, regardless of the downstream coronagraphic architecture. The mathematical techniques to finding ACAD DM shapes require to solve a complex differential equation. We will first discuss the scaling laws underlying this non-linear solution and their impact of DM placement and geometry wishing the optical design of an instrument. We will then consider the sensitivity to low order aberrations: in principle an ACAD solution that comprises large strokes will be more sensitive to these aberrations than one with smaller strokes. As a consequence, we will quantify this sensitive both using analytical models and numerical simulations. We will present diffractive end to end simulations and quantify the ultimate contrast and bandwidth achievable with ACAD, which can be reached by superposing using a classical linear wavefront control algorithms on top of the Monge Ampere solution. Finally, recent work has shown that coronagraph designs can also accommodate for secondary support structures and/or segments gaps, at a
Nano-Kelvin thermometry and temperature control: beyond the thermal noise limit
Weng, Wenle; Stace, Thomas M; Campbell, Geoff; Baynes, Fred N; Luiten, Andre N
2014-01-01
We demonstrate thermometry with a resolution of 80 $\\mathrm{nK} / \\sqrt{\\mathrm{Hz}}$ using an isotropic crystalline whispering-gallery mode resonator based on a dichroic dual-mode technique. We simultaneously excite two modes that have a mode frequency ratio very close to two ($\\pm0.3$ppm). The wavelength- and temperature-dependence of the refractive index means that the frequency difference between these modes is an ultra-sensitive proxy of the resonator temperature. This approach to temperature sensing automatically suppresses sensitivity to thermal expansion and vibrationally induced changes of the resonator. We also demonstrate active suppression of temperature fluctuations in the resonator by controlling the intensity of the driving laser. The residual temperature fluctuations are shown to be below the limits set by fundamental thermodynamic fluctuations of the resonator material.
Energy Technology Data Exchange (ETDEWEB)
Clemente, Paolo [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente
1997-07-01
Stone arches represent one of the most interesting topics in the field of the preservation of historic and monumental structures. The reason of this interest is related to the conservation of ancient structures, which have arrived until our age and to the relatively recent construction, especially railway bridges, of this century. In this paper the fundamental concepts of the limit design of stone arches are discussed. The simple case of funicular arch is first shown. Then the two classical shape are studied, parabolic and circular, subject to dead loads only. Finally, the effects of live loads and seismic loads are analyzed. The numerical analysis were carried out by means of computer codes. The results are plotted in diagrams to be used for the structural check.
Voss, P L; Kumar, P; Voss, Paul L.; K\\"{o}pr\\"{u}l\\"{u}, Kahraman G.; Kumar, Prem
2004-01-01
We present a quantum theory of nondegenerate phase-sensitive parametric amplification in a $\\chi^{(3)}$ nonlinear medium. The non-zero response time of the Kerr $(\\chi^{(3)})$ nonlinearity determines the quantum-limited noise figure of $\\chi^{(3)}$ parametric amplification, as well as the limit on quadrature squeezing. This non-zero response time of the nonlinearity requires coupling of the parametric process to a molecular-vibration phonon bath, causing the addition of excess noise through spontaneous Raman scattering. We present analytical expressions for the quantum-limited noise figure of frequency non-degenerate and frequency degenerate $\\chi^{(3)}$ parametric amplifiers operated as phase-sensitive amplifiers. We also present results for frequency non-degenerate quadrature squeezing. We show that our non-degenerate squeezing theory agrees with the degenerate squeezing theory of Boivin and Shapiro as degeneracy is approached. We have also included the effect of linear loss on the phase-sensitive process.
Visual recovery in cortical blindness is limited by high internal noise.
Cavanaugh, Matthew R; Zhang, Ruyuan; Melnick, Michael D; Das, Anasuya; Roberts, Mariel; Tadin, Duje; Carrasco, Marisa; Huxlin, Krystel R
2015-01-01
Damage to the primary visual cortex typically causes cortical blindness (CB) in the hemifield contralateral to the damaged hemisphere. Recent evidence indicates that visual training can partially reverse CB at trained locations. Whereas training induces near-complete recovery of coarse direction and orientation discriminations, deficits in fine motion processing remain. Here, we systematically disentangle components of the perceptual inefficiencies present in CB fields before and after coarse direction discrimination training. In seven human CB subjects, we measured threshold versus noise functions before and after coarse direction discrimination training in the blind field and at corresponding intact field locations. Threshold versus noise functions were analyzed within the framework of the linear amplifier model and the perceptual template model. Linear amplifier model analysis identified internal noise as a key factor differentiating motion processing across the tested areas, with visual training reducing internal noise in the blind field. Differences in internal noise also explained residual perceptual deficits at retrained locations. These findings were confirmed with perceptual template model analysis, which further revealed that the major residual deficits between retrained and intact field locations could be explained by differences in internal additive noise. There were no significant differences in multiplicative noise or the ability to process external noise. Together, these results highlight the critical role of altered internal noise processing in mediating training-induced visual recovery in CB fields, and may explain residual perceptual deficits relative to intact regions of the visual field.
Goda, K; Mikhailov, E E; Lam, P K; McClelland, D; Mavalvala, N; Goda, Keisuke; Kenzie, Kirk Mc; Mikhailov, Eugeniy E.; Lam, Ping Koy; Clelland, David Mc; Mavalvala, Nergis
2005-01-01
We study the effect of photothermal fluctuations on squeezed states of light through the photo-refractive effect and thermal expansion in a degenerate optical parametric amplifier (OPA). We also discuss the effect of the photothermal noise in various cases and how to minimize its undesirable consequences. We find that the photothermal noise in the OPA introduces a significant amount of noise on phase squeezed beams, making them less than ideal for low frequency applications such as gravitational wave (GW) interferometers, whereas amplitude squeezed beams are relatively immune to the photothermal noise and may represent the best choice for application in GW interferometers.
Spatial resolution limits for the localization of noise sources using direct sound mapping
DEFF Research Database (Denmark)
Comesana, D. Fernandez; Holland, K. R.; Fernandez Grande, Efren
2016-01-01
One of the main challenges arising from noise and vibration problems is how to identify the areas of a device, machine or structure that produce significant acoustic excitation, i.e. the localization of main noise sources. The direct visualization of sound, in particular sound intensity, has exte...
Szalma, J. L.; Hancock, P. A.
2012-01-01
Smith (2012) has provided pertinent observations on our recently published meta-analytic review (Szalma & Hancock, 2011) of the effects of acoustic noise on performance. His main points are as follows: (a) our review excluded some areas of research; (b) there were conceptual problems with our moderator analyses; and (c) limitations to…
Mcguirk, M.; Logan, L.
1980-01-01
A study was performed to determine the optimum focal plane configuration including optics, filters and detector-preamplifier selection. The configuration was optimized particularly with respect to minimizing the noise level, but fabrication considerations for a cryogenic environment were also taken into account. The noise terms from source, background, detector electronics and charged particle radiation were quantitatively evaluated. It appears that noise equivalent spectral radiance less than 10 to the -11th W/sq cm per sr per kayser can be achieved between 2.5 and 20 microns.
Limits of noise and confusion in the MWA GLEAM year 1 survey
Franzen, T M O; Callingham, J R; Ekers, R D; Hancock, P J; Hurley-Walker, N; Morgan, J; Seymour, N; Wayth, R B; White, S V; Bell, M E; Dwarakanath, K S; For, B; Gaensler, B M; Hindson, L; Johnston-Hollitt, M; Kapinska, A D; Lenc, E; McKinley, B; Offringa, A R; Procopio, P; Staveley-Smith, L; Wu, C; Zheng, Q
2016-01-01
The GaLactic and Extragalactic All-sky MWA survey (GLEAM) is a new relatively low resolution, contiguous 72-231 MHz survey of the entire sky south of declination +25 deg. In this paper, we outline one approach to determine the relative contribution of system noise, classical confusion and sidelobe confusion in GLEAM images. An understanding of the noise and confusion properties of GLEAM is essential if we are to fully exploit GLEAM data and improve the design of future low-frequency surveys. Our early results indicate that sidelobe confusion dominates over the entire frequency range, implying that enhancements in data processing have the potential to further reduce the noise.
Energy Technology Data Exchange (ETDEWEB)
Smeddinck, Ulrich; Koenig, Claudia (eds.)
2016-07-01
The volume is the documentation of an ENTRIA workshop discussion on limiting value definition in radiation protection including the following contributions: Introduction in radiation protection -fundamentals concepts of limiting values, heterogeneity; evaluation standards for dose in radiation protection in the context of final repository search; definition of limiting values in toxicology; public participation to limiting value definition - a perspective for the radiation protection regulation; actual developments in radiation protection.
Chow, Jong H; Littler, Ian C M; Rabeling, David S; McClelland, David E; Gray, Malcolm B
2008-05-26
We introduce a closed-loop feedback technique to actively control the coupling condition of an optical cavity, by employing amplitude modulation of the interrogating laser. We show that active impedance matching of the cavity facilitates optimal shot-noise sensing performance in a cavity enhanced system, while its control error signal can be used for intra-cavity absorption or loss signal extraction. We present the first demonstration of this technique with a fiber ring cavity, and achieved shot-noise limited loss sensitivity. We also briefly discuss further use of impedance matching control as a tool for other applications.
Directory of Open Access Journals (Sweden)
Ann-Cathrine Lindblad
Full Text Available The aim of the investigation was to study if dysfunctions associated to the cochlea or its regulatory system can be found, and possibly explain hearing problems in subjects with normal or near-normal audiograms. The design was a prospective study of subjects recruited from the general population. The included subjects were persons with auditory problems who had normal, or near-normal, pure tone hearing thresholds, who could be included in one of three subgroups: teachers, Education; people working with music, Music; and people with moderate or negligible noise exposure, Other. A fourth group included people with poorer pure tone hearing thresholds and a history of severe occupational noise, Industry. Ntotal = 193. The following hearing tests were used: - pure tone audiometry with Békésy technique, - transient evoked otoacoustic emissions and distortion product otoacoustic emissions, without and with contralateral noise; - psychoacoustical modulation transfer function, - forward masking, - speech recognition in noise, - tinnitus matching. A questionnaire about occupations, noise exposure, stress/anxiety, muscular problems, medication, and heredity, was addressed to the participants. Forward masking results were significantly worse for Education and Industry than for the other groups, possibly associated to the inner hair cell area. Forward masking results were significantly correlated to louder matched tinnitus. For many subjects speech recognition in noise, left ear, did not increase in a normal way when the listening level was increased. Subjects hypersensitive to loud sound had significantly better speech recognition in noise at the lower test level than subjects not hypersensitive. Self-reported stress/anxiety was similar for all groups. In conclusion, hearing dysfunctions were found in subjects with tinnitus and other auditory problems, combined with normal or near-normal pure tone thresholds. The teachers, mostly regarded as a group
Sanders, Steve; Dawson, Jay W.; Park, Namkyoo; Vahala, Kerry J.
1992-01-01
The intensity noise of an erbium-doped fiber ring laser is measured relative to the standard quantum limit. Over a tuning range of 24 nm, the noise power is within 20 dB of the shot noise floor and varies linearly with laser output power. Oscillations in the noise power spectrum are observed and attributed to beating of the lasing mode with other, strongly damped cavity modes.
Beijer, M.P.
2017-01-01
The concept of positive obligations is familiar to different legal systems that seek to protect fundamental rights. This concept means that states are required to take active measures to protect fundamental rights, for example by adopting a general legal framework to regulate same-sex relationships
Kumar, Ashutosh; Heilmann, M.; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M.; Christiansen, Silke H.; Kumar, Vikram; Singh, Rajendra
2016-01-01
The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained. PMID:27282258
Kumar, Ashutosh; Heilmann, M; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M; Christiansen, Silke H; Kumar, Vikram; Singh, Rajendra
2016-01-01
The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained.
Kawamura, Y; Kanegae, R
2016-06-17
Cooling the vibration amplitude of a microcantilever as low as possible is important to improve the sensitivity and resolutions of various types of scanning type microscopes and sensors making use of it. When the vibration amplitude is controlled to be smaller using a feed back control system, it is known that the obtainable minimum amplitude of the vibration is limited by the floor noise level of the detection system. In this study, we demonstrated that the amplitude of the thermal vibration of a microcantilever was suppressed to be about 0.15 pmHz(-1/2), which is the same value with the floor noise level, without the assistance of external cryogenic cooling. We think that one of the reason why we could reach the smaller amplitude at room temperature is due to stiffer spring constant of the lever, which leads to higher natural frequency and consequently lower floor noise level. The other reason is considered to be due to the increase in the laser power for the diagnostics, which lead to the decrease in the signal to noise ratio determined by the optical shot noise.
Kawamura, Y.; Kanegae, R.
2016-06-01
Cooling the vibration amplitude of a microcantilever as low as possible is important to improve the sensitivity and resolutions of various types of scanning type microscopes and sensors making use of it. When the vibration amplitude is controlled to be smaller using a feed back control system, it is known that the obtainable minimum amplitude of the vibration is limited by the floor noise level of the detection system. In this study, we demonstrated that the amplitude of the thermal vibration of a microcantilever was suppressed to be about 0.15 pmHz‑1/2, which is the same value with the floor noise level, without the assistance of external cryogenic cooling. We think that one of the reason why we could reach the smaller amplitude at room temperature is due to stiffer spring constant of the lever, which leads to higher natural frequency and consequently lower floor noise level. The other reason is considered to be due to the increase in the laser power for the diagnostics, which lead to the decrease in the signal to noise ratio determined by the optical shot noise.
Phase-noise limitations in continuous-variable quantum key distribution with homodyne detection
Corvaja, Roberto
2017-02-01
In continuous-variables quantum key distribution with coherent states, the advantage of performing the detection by using standard telecoms components is counterbalanced by the lack of a stable phase reference in homodyne detection due to the complexity of optical phase-locking circuits and to the unavoidable phase noise of lasers, which introduces a degradation on the achievable secure key rate. Pilot-assisted phase-noise estimation and postdetection compensation techniques are used to implement a protocol with coherent states where a local laser is employed and it is not locked to the received signal, but a postdetection phase correction is applied. Here the reduction of the secure key rate determined by the laser phase noise, for both individual and collective attacks, is analytically evaluated and a scheme of pilot-assisted phase estimation proposed, outlining the tradeoff in the system design between phase noise and spectral efficiency. The optimal modulation variance as a function of the phase-noise amount is derived.
Energy Technology Data Exchange (ETDEWEB)
Steven, Heinz [Data Analysis and Consultancy, Heinsberg (Germany)
2012-03-15
With COM(2011) 856 final from 09.12.2011 the EU Commission launched a proposal for a regulation of the European Parliament and of the Council on the sound level of motor vehicles. This proposal is related to motor vehicles having at least four wheels. Objective and aim are described as follows: ''The objective of the proposal is to ensure a high level of health and environmental protection and to safeguard the Internal Market for motor vehicles as regards their sound level. The proposal aims at reducing environmental noise by introducing a new test method for measuring noise emissions, by lowering the noise limit values, by including additional sound emission provisions in the type-approval procedure...'' (see paragraph 1 of the explanatory memorandum). Under the bullet point ''- new limit values'' of paragraph 1 of the explanatory memorandum the following statements are listed: ''On the basis of the results of the monitoring data an impact assessment has been prepared with different policy options for the noise test method and corresponding limit values. According to the most preferable option the limit values for light and medium size vehicles will be lowered in two steps of each 2 dB(A) and for heavy vehicles in a first step of 1 and a second step of 2 dB(A). This will result in a reduction of the noise impact of about 3 dB(A) for free flowing traffic and up to 4 dB(A) for intermittent traffic. The reduction of the number of highly annoyed people will be 25 %. The cost-benefit ratio for this measure is estimated to be around 20 times in favour of the noise reduction compared to no action taken.'' The forecast for the reduction of the noise impact in real traffic is far too optimistic. It is highly unlikely that the reduction of limit values by 3 to 4 dB will lead to a reduction of the noise impact in real traffic by the same amount without any deterioration factor. Own calculations with the TRANECAM
Noise limitations of multiplier phototubes in the radiation environment of space
Viehmann, W.; Eubanks, A. G.
1976-01-01
The contributions of Cerenkov emission, luminescence, secondary electron emission, and bremsstrahlung to radiation-induced data current and noise of multiplier phototubes were analyzed quantitatively. Fluorescence and Cerenkov emission in the tube window are the major contributors and can quantitatively account for dark count levels observed in orbit. Radiation-induced noise can be minimized by shielding, tube selection, and mode of operation. Optical decoupling of windows and cathode (side-window tubes) leads to further reduction of radiation-induced dark counts, as does reducing the window thickness and effective cathode area, and selection of window/cathode combinations of low fluorescence efficiency. In trapped radiation-free regions of near-earth orbits and in free space, Cerenkov emission by relativistic particles contributes predominantly to the photoelectron yield per event. Operating multiplier phototubes in the photon (pulse) counting mode will discriminate against these large pulses and substantially reduce the dark count and noise to levels determined by fluorescence.
Gallavotti Cohen Theorem, Chaotic Hypothesis and the Zero-Noise Limit
Kurchan, Jorge
2007-09-01
The Fluctuation Relation for a stationary state, kept at constant energy by a deterministic thermostat—the Gallavotti-Cohen Theorem— relies on the ergodic properties of the system considered. We show that when perturbed by an energy-conserving random noise, the relation follows trivially for any system at finite noise amplitude. The time needed to achieve stationarity may stay finite as the noise tends to zero, or it may diverge. In the former case the Gallavotti-Cohen result is recovered, while in the latter case, the crossover time may be computed from the action of `instanton' orbits that bridge attractors and repellors. We suggest that the `Chaotic Hypothesis' of Gallavotti, Cohen and Ruelle can thus be reformulated as a matter of stochastic stability of the measure in trajectory space. In this form this hypothesis may be directly tested.
Noise limits in a front-end system based on time-over-threshold signal processing
Manfredi, P F; Mandelli, E; Perazzo, A; Re, V
2000-01-01
An analog signal processor based on the Time-over-Threshold (ToT) range compression is employed in the front-end section of the readout chip of the microstrip vertex detector for the BaBar experiment. The paper, after describing the circuit solutions that have been adopted to optimize the ToT operation, focuses on the noise aspects of the ToT processor. Comparisons are made between the signal-to-noise ratio in the linear processor preceding the ToT circuit and that obtained at the output of the entire analog channel including the ToT function.
Thermal Noise Canceling in LNAs: A Review
Nauta, Bram; Klumperink, Eric A.M.; Bruccoleri, Federico
2004-01-01
Most wide-band amplifiers suffer from a fundamental trade-off between noise figure NF and source impedance matching, which limits NF to values typically above 3dB. Recently, a feed-forward noise canceling technique has been proposed to break this trade-off. This paper reviews the principle of the te
Quantum-Noise-Limited Sensitivity Enhancement of a Passive Optical Cavity by a Fast-Light Medium
Smith, David D.; Luckay, H. A.; Chang, Hongrok; Myneni, Krishna
2016-01-01
We demonstrate for a passive optical cavity containing a dispersive atomic medium, the increase in scale factor near the critical anomalous dispersion is not cancelled by mode broadening or attenuation, resulting in an overall increase in the predicted quantum-noise-limited sensitivity. Enhancements of over two orders of magnitude are measured in the scale factor, which translates to greater than an order-of-magnitude enhancement in the predicted quantum-noise-limited measurement precision, by temperature tuning a low-pressure vapor of non-interacting atoms in a low-finesse cavity close to the critical anomalous dispersion condition. The predicted enhancement in sensitivity is confirmed through Monte-Carlo numerical simulations.
Directory of Open Access Journals (Sweden)
B. Langford
2015-03-01
Full Text Available All eddy-covariance flux measurements are associated with random uncertainties which are a combination of sampling error due to natural variability in turbulence and sensor noise. The former is the principal error for systems where the signal-to-noise ratio of the analyser is high, as is usually the case when measuring fluxes of heat, CO2 or H2O. Where signal is limited, which is often the case for measurements of other trace gases and aerosols, instrument uncertainties dominate. We are here applying a consistent approach based on auto- and cross-covariance functions to quantifying the total random flux error and the random error due to instrument noise separately. As with previous approaches, the random error quantification assumes that the time-lag between wind and concentration measurement is known. However, if combined with commonly used automated methods that identify the individual time-lag by looking for the maximum in the cross-covariance function of the two entities, analyser noise additionally leads to a systematic bias in the fluxes. Combining datasets from several analysers and using simulations we show that the method of time-lag determination becomes increasingly important as the magnitude of the instrument error approaches that of the sampling error. The flux bias can be particularly significant for disjunct data, whereas using a prescribed time-lag eliminates these effects (provided the time-lag does not fluctuate unduly over time. We also demonstrate that when sampling at higher elevations, where low frequency turbulence dominates and covariance peaks are broader, both the probability and magnitude of bias are magnified. We show that the statistical significance of noisy flux data can be increased (limit of detection can be decreased by appropriate averaging of individual fluxes, but only if systematic biases are avoided by using a prescribed time-lag. Finally, we make recommendations for the analysis and reporting of data with
Seto, Keisuke; Tsukada, Toshiaki; Okuda, Yoshinao; Tokunaga, Eiji; Kobayashi, Takayoshi
2014-02-01
We report on the development of a balanced detector suited for multicolor imaging. The source pulsed light is split into probe and reference pulsed light. The reference pulse is delayed through an optical path and the probe and reference pulses are detected by a single photodetector. The signs of the detected signals of the probe and reference pulses are flipped based on a signal synchronous to the light source. Then, the signals are averaged through a low-pass filter. The output signal is proportional to the intensity difference between the probe and the reference. This balanced detector has two features: (1) both the probe and reference pulsed lights are detected by a single photodetector and (2) a voltage bias on the sign flipping compensates for the optical-intensity unbalance between the probe and reference pulsed lights. The first feature enables the probe and reference pulses to travel along a common optical path from a sample through a spectrograph to the photodetector, which minimizes the intensity unbalance between the probe and reference pulses during imaging and spectroscopy. The second feature ensures the complete balanced-detection in whole wavelength range by compensating for the optical unbalance created by deviations in the splitting ratios of the probe and reference lights at different wavelengths. Although a higher signal to noise ratio (SNR) reached to near shot noise limited SNR is attained by attaching a resonator to the photodetector for pulse repetition, the electrical bias cannot compensate for the optical balance. This unbalance is, however, corrected by adjusting the phase of the synchronous signal. We applied the present balanced detection to a stimulated Raman microscope with supercontinuum probe light and demonstrated its noise cancelling performance through capturing polystyrene beads.
Cetacean noise criteria revisited in the light of proposed exposure limits for harbour porpoises
DEFF Research Database (Denmark)
Tougaard, Jakob; Wright, Andrew John; Madsen, Professor Peter Teglberg
2015-01-01
that harbour and finless porpoises are more sensitive to sound than expected from extrapolations based on results from bottlenose dolphins. Furthermore, the results from TTS experiments and field studies of behavioural reactions to noise, suggest that response thresholds and TTS critically depend on stimulus...... frequency. Sound exposure levels for pure tones that induce TTS are reasonably consistent at about 100 dB above the hearing threshold for pure tones and sound pressure thresholds for avoidance reactions are in the range of 40–50 dB above the hearing threshold. We propose that frequency weighting...
Directory of Open Access Journals (Sweden)
Kenji Hata
2013-07-01
Full Text Available Understanding the fundamental mechanisms and limiting processes of the growth of single-walled carbon nanotube (SWCNT would serve as a guide to achieve further control on structural parameters of SWCNT. In this paper, we have studied the growth kinetics of a series of SWCNT forests continuously spanning a wide range of diameters (1.9–3.2 nm, and have revealed an additional fundamental growth limiting process where the mass of the individual SWCNT is determined by the individual catalyst volume. Calculation of the conversion rate of carbon atoms into CNTs per Fe atom is 2 × 102 atoms per second. This rate limiting process provides an important understanding where the larger diameter SWCNT would grow faster, and thus be more suited for mass production.
Fundamental ecology is fundamental.
Courchamp, Franck; Dunne, Jennifer A; Le Maho, Yvon; May, Robert M; Thébaud, Christophe; Hochberg, Michael E
2015-01-01
The primary reasons for conducting fundamental research are satisfying curiosity, acquiring knowledge, and achieving understanding. Here we develop why we believe it is essential to promote basic ecological research, despite increased impetus for ecologists to conduct and present their research in the light of potential applications. This includes the understanding of our environment, for intellectual, economical, social, and political reasons, and as a major source of innovation. We contend that we should focus less on short-term, objective-driven research and more on creativity and exploratory analyses, quantitatively estimate the benefits of fundamental research for society, and better explain the nature and importance of fundamental ecology to students, politicians, decision makers, and the general public. Our perspective and underlying arguments should also apply to evolutionary biology and to many of the other biological and physical sciences. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.
Jervis, D.
2016-12-01
Field-deployable trace gas monitors are important for understanding a multitude of atmospheric processes: from forest photosynthesis and respiration [1], to fugitive methane emissions [2] and satellite measurement validation [3]. Consequently, a detailed knowledge of the performance limitations of these instruments is essential in order to establish reliable datasets. We present the short-term ( >1 Hz) performance of a long-pass direct absorption spectrometer as a function of the optical density of the absorption transition being probed. In particular, we identify fluctuations in the laser intensity as limiting the optical density uncertainty to 4x10-6/√Hz for weak transitions, and noise in the laser drive current as limiting the fractional noise in the optical density to 4x10-5/√Hz for deep transitions. We provide numerical and analytical predictions for both effects, as well as using the understanding of this phenomena to estimate how noise on neighboring strong and weak transitions couple to each other. All measurements were performed using the Aerodyne Research TILDAS Monitor, but are general to any instrument that uses direct absorption spectroscopy as a detection method. Wehr, R., et al. "Seasonality of temperate forest photosynthesis and daytime respiration." Nature 534.7609 (2016): 680-683. Conley, S., et al. "Methane emissions from the 2015 Aliso Canyon blowout in Los Angeles, CA." Science 351.6279 (2016): 1317-1320. Emmons, L. K., et al. "Validation of Measurements of Pollution in the Troposphere (MOPITT) CO retrievals with aircraft in situ profiles." Journal of Geophysical Research: Atmospheres 109.D3 (2004).
Sanders, Steve; Park, Namkyoo; Dawson, Jay W.; Vahala, Kerry J.
1992-01-01
The high frequency intensity noise of a tandem fiber Fabry–Perot erbium-doped fiber ring laser is reduced to the standard quantum limit, with a 0.5 dB experimental uncertainty. Noise reduction of >~14 dB is achieved by intracavity spectral filtering of weak side modes using a narrow-band fiber Fabry–Perot etalon.
Siman, W.; Mawlawi, O. R.; Mikell, J. K.; Mourtada, F.; Kappadath, S. C.
2017-01-01
The aims of this study were to evaluate the effects of noise, motion blur, and motion compensation using quiescent-period gating (QPG) on the activity concentration (AC) distribution—quantified using the cumulative AC volume histogram (ACVH)—in count-limited studies such as 90Y-PET/CT. An International Electrotechnical Commission phantom filled with low 18F activity was used to simulate clinical 90Y-PET images. PET data were acquired using a GE-D690 when the phantom was static and subject to 1-4 cm periodic 1D motion. The static data were down-sampled into shorter durations to determine the effect of noise on ACVH. Motion-degraded PET data were sorted into multiple gates to assess the effect of motion and QPG on ACVH. Errors in ACVH at AC90 (minimum AC that covers 90% of the volume of interest (VOI)), AC80, and ACmean (average AC in the VOI) were characterized as a function of noise and amplitude before and after QPG. Scan-time reduction increased the apparent non-uniformity of sphere doses and the dispersion of ACVH. These effects were more pronounced in smaller spheres. Noise-related errors in ACVH at AC20 to AC70 were smaller (15%). The accuracy of ACmean was largely independent of the total count. Motion decreased the observed AC and skewed the ACVH toward lower values; the severity of this effect depended on motion amplitude and tumor diameter. The errors in AC20 to AC80 for the 17 mm sphere were -25% and -55% for motion amplitudes of 2 cm and 4 cm, respectively. With QPG, the errors in AC20 to AC80 of the 17 mm sphere were reduced to -15% for motion amplitudes 0.5, QPG was effective at reducing errors in ACVH despite increases in image non-uniformity due to increased noise. ACVH is believed to be more relevant than mean or maximum AC to calculate tumor control and normal tissue complication probability. However, caution needs to be exercised when using ACVH in post-therapy 90Y imaging because of its susceptibility to image
Statistical processes limiting the noise of a screen-film system: II
Beutel, Jacob; Shaw, Rodney; Yampolsky, Michael
1995-05-01
In a recent publication we demonstrated that the increase in image noise which results from exposing a film via a phosphor screen can be attributed entirely to the increased extent of the autocorrelation interval introduced by the screen, and not to any change in the shape or scale of the probability distribution function which governs the fluctuations about the mean level. This result implies that the (0,0)-value of the autocovariance function is independent of the degree of so-called quantum mottle and since the autocovariance function, ACV(x,y), and the Wiener Spectrum, WS(u,v), are Fourier transform pairs, it follows that the integral of the Wiener Spectrum over all spatial frequencies (u,v) must share this independence. Since this result was counterintuitive to existing assumptions of the role of screen and film in defining the Wiener Spectrum (i.e., a simple additive combination of quantum mottle and film grain), we now investigate this relationship in more detail in order to provide a more complete insight. For this purpose we have simulated a set of controlled images which correspond to a wide range of screen correlation intervals, from 192 micrometers down to uncorrelated film noise. Included in this simulation we have also explored the role of the overall amplification factor, i.e., the average number of image grains associated with an x-ray quantum. The results of these simulations are presented here, and confirm our previous findings, by establishing the invariance of the scale (0,0) value of the ACV.
Directory of Open Access Journals (Sweden)
Daniel Oberfeld
Full Text Available To identify factors limiting performance in multitone intensity discrimination, we presented sequences of five pure tones alternating in level between loud (85 dB SPL and soft (30, 55, or 80 dB SPL. In the "overall-intensity task", listeners detected a level increment on all of the five tones. In the "masking task", the level increment was imposed only on the soft tones, rendering the soft tones targets and loud tones task-irrelevant maskers. Decision weights quantifying the importance of the five tone levels for the decision were estimated using methods of molecular psychophysics. Compatible with previous studies, listeners placed higher weights on the loud tones than on the soft tones in the overall-intensity condition. In the masking task, the decisions were systematically influenced by the to-be-ignored loud tones (maskers. Using a maximum-likelihood technique, we estimated the internal noise variance and tested whether the internal noise was higher in the alternating-level five-tone sequences than in sequences presenting only the soft or only the loud tones. For the overall-intensity task, we found no evidence for increased internal noise, but listeners applied suboptimal decision weights. These results are compatible with the hypothesis that the presence of the loud tones does not impair the precision of the representation of the intensity of the soft tones available at the decision stage, but that this information is not used in an optimal fashion due to a difficulty in attending to the soft tones. For the masking task, in some cases our data indicated an increase in internal noise. Additionally, listeners applied suboptimal decision weights. The maximum-likelihood analyses we developed should also be useful for other tasks or other sensory modalities.
Alam, Muhammad A
2016-01-01
Bifacial tandem cells promise to reduce three fundamental losses (above-bandgap, below bandgap, and the uncollected light between panels) inherent in classical single junction PV systems. The successive filtering of light through the bandgap cascade, and requirement of current continuity make optimization of tandem cells difficult, accessible only to numerical solution through computer modeling. The challenge is even more complicated for bifacial design. In this paper, we use an elegantly simple Markov chain approach to show that the essential physics of optimization is intuitively obvious, and deeply insightful results can obtained analytically with a few lines of algebra. This powerful approach reproduces, as special cases, all the known results of traditional/bifacial tandem cells, and highlights the asymptotic efficiency gain of these technologies.
Motes, Keith R; Olson, Jonathan P; Rabeaux, Evan J; Dowling, Jonathan P; Olson, S Jay; Rohde, Peter P
2015-05-01
Quantum number-path entanglement is a resource for supersensitive quantum metrology and in particular provides for sub-shot-noise or even Heisenberg-limited sensitivity. However, such number-path entanglement has been thought to be resource intensive to create in the first place--typically requiring either very strong nonlinearities, or nondeterministic preparation schemes with feedforward, which are difficult to implement. Very recently, arising from the study of quantum random walks with multiphoton walkers, as well as the study of the computational complexity of passive linear optical interferometers fed with single-photon inputs, it has been shown that such passive linear optical devices generate a superexponentially large amount of number-path entanglement. A logical question to ask is whether this entanglement may be exploited for quantum metrology. We answer that question here in the affirmative by showing that a simple, passive, linear-optical interferometer--fed with only uncorrelated, single-photon inputs, coupled with simple, single-mode, disjoint photodetection--is capable of significantly beating the shot-noise limit. Our result implies a pathway forward to practical quantum metrology with readily available technology.
Meng, Qinglin; Zheng, Nengheng; Li, Xia
2016-01-01
Temporal envelope-based signal processing strategies are widely used in cochlear-implant (CI) systems. It is well recognized that the inability to convey temporal fine structure (TFS) in the stimuli limits CI users' performance, but it is still unclear how to effectively deliver the TFS. A strategy known as the temporal limits encoder (TLE), which employs an approach to derive the amplitude modulator to generate the stimuli coded in an interleaved-sampling strategy, has recently been proposed. The TLE modulator contains information related to the original temporal envelope and a slow-varying TFS from the band signal. In this paper, theoretical analyses are presented to demonstrate the superiority of TLE compared with two existing strategies, the clinically available continuous-interleaved-sampling (CIS) strategy and the experimental harmonic-single-sideband-encoder strategy. Perceptual experiments with vocoder simulations in normal-hearing listeners are conducted to compare the performance of TLE and CIS on two tasks (i.e., Mandarin speech reception in babble noise and tone recognition in quiet). The performance of the TLE modulator is mostly better than (for most tone-band vocoders) or comparable to (for noise-band vocoders) the CIS modulator on both tasks. This work implies that there is some potential for improving the representation of TFS with CIs by using a TLE strategy.
Energy Technology Data Exchange (ETDEWEB)
Michel, T. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany)]. E-mail: thilo.michel@physik.uni-erlangen.de; Anton, G. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Boehnel, M. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Durst, J. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Firsching, M. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Korn, A. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Kreisler, B. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Loehr, A. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Nachtrab, F. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Niederloehner, D. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Sukowski, F. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Takoukam Talla, P. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany)
2006-12-01
We outline in this paper that the noise of a photon counting pixel detector depends on the detection efficiency and the average multiplicity of counts per interacting photon. We give a simple expression for the signal-to-noise ratio (SNR) and zero-frequency detective quantum efficiency (DQE). We describe a method to determine the DQE from measured data and to optimize the DQE as a function of energy threshold.
Pueyo, Laurent; Norman, Colin; Soummer, Rémi; Perrin, Marshall; N'Diaye, Mamadou; Choquet, Élodie; Hoffmann, Jordan; Carlotti, Alexis; Mawet, Dimitri
2014-08-01
We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential Deformable Mirrors to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and / or segment gaps. We solve the highly non-linear Monge-Ampere equation that is the fundamental equation describing the physics of phase induced amplitude modulation. We determine the optimum configuration for our two sequential Deformable Mirror system and show that high-throughput and high contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries similar to JWST, ACAD can attain at least 10-7 in contrast and an order of magnitude higher for future Extremely Large Telescopes, even when the pupil features a "missing segment" . Because the converging non-linear mappings resulting from our Deformable Mirror shapes damps near-field diffraction artifacts in the vicinity of the discontinuities this solution is particularly appealing in terms of spectral bandwidth. We present preliminary results that illustrate the performances of ACAD in the presence of diffraction for apertures for with secondary support structures of varying width and argue that the ultimate contrast achieved can by combining ACAD with modern wavefront control algorithms.
Fundamentally updating fundamentals.
Armstrong, Gail; Barton, Amy
2013-01-01
Recent educational research indicates that the six competencies of the Quality and Safety Education for Nurses initiative are best introduced in early prelicensure clinical courses. Content specific to quality and safety has traditionally been covered in senior level courses. This article illustrates an effective approach to using quality and safety as an organizing framework for any prelicensure fundamentals of nursing course. Providing prelicensure students a strong foundation in quality and safety in an introductory clinical course facilitates early adoption of quality and safety competencies as core practice values.
Enhanced dissipation, hypoellipticity, and anomalous small noise inviscid limits in shear flows
Bedrossian, Jacob
2015-01-01
We analyze the decay and instant regularization properties of the evolution semigroups generated by two-dimensional drift-diffusion equations in which the scalar is advected by a shear flow and dissipated by full or partial diffusion. We consider both the space-periodic $\\mathbb{T}^2$ setting and the case of a bounded channel $\\mathbb{T}\\times [0,1]$ with no-flux boundary conditions. In the infinite P\\'eclet number limit (diffusivity $\
Invariant Measures for Passive Scalars in the Small Noise Inviscid Limit
Bedrossian, Jacob; Coti Zelati, Michele; Glatt-Holtz, Nathan
2016-11-01
We consider a class of invariant measures for a passive scalar f driven by an incompressible velocity field {\\varvec{u}}, on a d-dimensional periodic domain, satisfying δt f + \\varvec{u} \\cdot nabla f = 0, qquad f(0)=f0. The measures are obtained as limits of stochastic viscous perturbations. We prove that the span of the H 1 eigenfunctions of the operator {\\varvec{u} \\cdot nabla} contains the support of these measures. We also analyze several explicit examples: when {\\varvec{u}} is a shear flow or a relaxation enhancing flow (a generalization of weakly mixing), we can characterize the limiting measure uniquely and compute its covariance structure. We also consider the case of two-dimensional cellular flows, for which further regularity properties of the functions in the support of the measure can be deduced. The main results are proved with the use of spectral theory results, in particular the RAGE theorem, which are used to characterize large classes of orbits of the inviscid problem that are growing in H 1.
High signal-to-noise ratio observations and the ultimate limits of precision pulsar timing
Oslowski, Stefan; Hobbs, George; Bailes, Matthew; Demorest, Paul
2011-01-01
We demonstrate that the sensitivity of high-precision pulsar timing experiments will be ultimately limited by the broadband intensity modulation that is intrinsic to the pulsar's stochastic radio signal. That is, as the peak flux of the pulsar approaches that of the system equivalent flux density, neither greater antenna gain nor increased instrumental bandwidth will improve timing precision. These conclusions proceed from an analysis of the covariance matrix used to characterise residual pulse profile fluctuations following the template matching procedure for arrival time estimation. We perform such an analysis on 25 hours of high-precision timing observations of the closest and brightest millisecond pulsar, PSR J0437-4715. In these data, the standard deviation of the post-fit arrival time residuals is approximately four times greater than that predicted by considering the system equivalent flux density, mean pulsar flux and the effective width of the pulsed emission. We develop a technique based on principa...
A gravitational wave observatory operating beyond the quantum shot-noise limit
Ligo Scientific Collaboration; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Adams, C.; Adhikari, R.; Affeldt, C.; Allen, B.; Allen, G. S.; Amador Ceron, E.; Amariutei, D.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Arain, M. A.; Araya, M. C.; Aston, S. M.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballmer, S.; Barker, D.; Barr, B.; Barriga, P.; Barsotti, L.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Batch, J.; Bauchrowitz, J.; Behnke, B.; Bell, A. S.; Belopolski, I.; Benacquista, M.; Berliner, J. M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biswas, R.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bondarescu, R.; Bork, R.; Born, M.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Breyer, J.; Bridges, D. O.; Brinkmann, M.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brummitt, A.; Buonanno, A.; Burguet-Castell, J.; Burmeister, O.; Byer, R. L.; Cadonati, L.; Camp, J. B.; Campsie, P.; Cannizzo, J.; Cannon, K.; Cao, J.; Capano, C. D.; Caride, S.; Caudill, S.; Cavagliá, M.; Cepeda, C.; Chalermsongsak, T.; Chalkley, E.; Charlton, P.; Chelkowski, S.; Chen, Y.; Christensen, N.; Cho, H.; Chua, S. S. Y.; Chung, S.; Chung, C. T. Y.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J.; Clayton, J. H.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M.; Couvares, P.; Coward, D. M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Cumming, A.; Cunningham, L.; Cutler, R. M.; Dahl, K.; Danilishin, S. L.; Dannenberg, R.; Danzmann, K.; Daudert, B.; Daveloza, H.; Davies, G.; Daw, E. J.; Dayanga, T.; Debra, D.; Degallaix, J.; Dent, T.; Dergachev, V.; Derosa, R.; Desalvo, R.; Dhurandhar, S.; Diguglielmo, J.; di Palma, I.; Díaz, M.; Donovan, F.; Dooley, K. L.; Dorsher, S.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Engel, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fairhurst, S.; Fan, Y.; Farr, B. F.; Farr, W.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Finn, L. S.; Fisher, R. P.; Flanigan, M.; Foley, S.; Forsi, E.; Fotopoulos, N.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fulda, P. J.; Fyffe, M.; Ganija, M. R.; Garcia, J.; Garofoli, J. A.; Geng, R.; Gergely, L. Á.; Gholami, I.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Gill, C.; Goetz, E.; Goggin, L. M.; González, G.; Gorodetsky, M. L.; Goßler, S.; Graef, C.; Grant, A.; Gras, S.; Gray, C.; Gray, N.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Grosso, R.; Grote, H.; Grunewald, S.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Ha, T.; Hage, B.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Heintze, M. C.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Hong, T.; Hooper, S.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hughey, B.; Huynh-Dinh, T.; Husa, S.; Huttner, S. H.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Izumi, K.; Jacobson, M.; Jang, H.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kamaretsos, I.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Keresztes, Z.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B.; Kim, C.; Kim, D.; Kim, H.; Kim, K.; Kim, N.; Kim, Y.-M.; King, P. J.; Kinsey, M.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R.; Koranda, S.; Korth, W. Z.; Kozak, D.; Kringel, V.; Krishnamurthy, S.; Krishnan, B.; Kuehn, G.; Kumar, R.; Kwee, P.; Lam, P. K.; Landry, M.; Lang, M.; Lantz, B.; Lastzka, N.; Lawrie, C.; Lazzarini, A.; Leaci, P.; Lee, C. H.; Lee, H. M.; Leindecker, N.; Leong, J. R.; Leonor, I.; Li, J.; Lindquist, P. E.; Lockerbie, N. A.; Lodhia, D.; Lormand, M.; Luan, J.; Lubinski, M.; Lück, H.; Lundgren, A. P.; MacDonald, E.; Machenschalk, B.; Macinnis, M.; MacLeod, D. M.; Mageswaran, M.; Mailand, K.; Mandel, I.; Mandic, V.; Marandi, A.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; McKechan, D. J. A.; Meadors, G. D.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Menendez, D.
2011-12-01
Around the globe several observatories are seeking the first direct detection of gravitational waves (GWs). These waves are predicted by Einstein's general theory of relativity and are generated, for example, by black-hole binary systems. Present GW detectors are Michelson-type kilometre-scale laser interferometers measuring the distance changes between mirrors suspended in vacuum. The sensitivity of these detectors at frequencies above several hundred hertz is limited by the vacuum (zero-point) fluctuations of the electromagnetic field. A quantum technology--the injection of squeezed light--offers a solution to this problem. Here we demonstrate the squeezed-light enhancement of GEO600, which will be the GW observatory operated by the LIGO Scientific Collaboration in its search for GWs for the next 3-4 years. GEO600 now operates with its best ever sensitivity, which proves the usefulness of quantum entanglement and the qualification of squeezed light as a key technology for future GW astronomy.
McCreery, Ryan W; Stelmachowicz, Patricia G
2013-09-01
Understanding speech in acoustically degraded environments can place significant cognitive demands on school-age children who are developing the cognitive and linguistic skills needed to support this process. Previous studies suggest the speech understanding, word learning, and academic performance can be negatively impacted by background noise, but the effect of limited audibility on cognitive processes in children has not been directly studied. The aim of the present study was to evaluate the impact of limited audibility on speech understanding and working memory tasks in school-age children with normal hearing. Seventeen children with normal hearing between 6 and 12 years of age participated in the present study. Repetition of nonword consonant-vowel-consonant stimuli was measured under conditions with combinations of two different signal to noise ratios (SNRs; 3 and 9 dB) and two low-pass filter settings (3.2 and 5.6 kHz). Verbal processing time was calculated based on the time from the onset of the stimulus to the onset of the child's response. Monosyllabic word repetition and recall were also measured in conditions with a full bandwidth and 5.6 kHz low-pass cutoff. Nonword repetition scores decreased as audibility decreased. Verbal processing time increased as audibility decreased, consistent with predictions based on increased listening effort. Although monosyllabic word repetition did not vary between the full bandwidth and 5.6 kHz low-pass filter condition, recall was significantly poorer in the condition with limited bandwidth (low pass at 5.6 kHz). Age and expressive language scores predicted performance on word recall tasks, but did not predict nonword repetition accuracy or verbal processing time. Decreased audibility was associated with reduced accuracy for nonword repetition and increased verbal processing time in children with normal hearing. Deficits in free recall were observed even under conditions where word repetition was not affected
Bolton, Adam S
2009-01-01
We describe a new algorithm for the "perfect" extraction of one-dimensional spectra from two-dimensional CCD images of optical fiber spectrographs, based on accurate two-dimensional (2D) forward modeling of the raw pixel data. The algorithm is correct for arbitrarily complicated 2D point-spread functions (PSFs), as compared to the traditional optimal extraction algorithm, which is only correct for a limited class of separable PSFs. The algorithm results in statistically independent extracted samples in the 1D spectrum, and preserves the full native resolution of the 2D spectrograph without degradation. Both the statistical errors and the 1D resolution of the extracted spectrum are precisely determined. Using a model PSF similar to that found in the red channel of the Sloan Digital Sky Survey spectrograph, we compare the performance of our algorithm to that of cross-section based optimal extraction, and also demonstrate that our method allows coaddition and foreground estimation to be carried out as an integra...
,
2011-01-01
Around the globe several observatories are seeking the first direct detection of gravitational waves (GWs). These waves are predicted by Einstein's General Theory of Relativity [Einstein, A., Annalen der Physik 49, 769-822 (1916)] and are generated e.g. by black-hole binary systems [Sathyaprakash, B. S. and Schutz, B. F., Living Rev. Relativity 12, 2 (2009)]. Current GW detectors are Michelson-type kilometer-scale laser interferometers measuring the distance changes between in vacuum suspended mirrors. The sensitivity of these detectors at frequencies above several hundred hertz is limited by the vacuum (zero-point) fluctuations of the electromagnetic field. A quantum technology - the injection of squeezed light [Caves, C. M., Phys. Rev. D 23, 1693-1708 (1981)] - offers a solution to this problem. Here we demonstrate the squeezed-light enhancement of GEO600, which will be the GW observatory operated by the LIGO Scientific Collaboration in its search for GWs for the next 3-4 years. GEO600 now operates with its...
Bolton, Adam S.; Schlegel, David J.
2010-02-01
We describe a new algorithm for the “perfect” extraction of one-dimensional (1D) spectra from two-dimensional (2D) digital images of optical fiber spectrographs, based on accurate 2D forward modeling of the raw pixel data. The algorithm is correct for arbitrarily complicated 2D point-spread functions (PSFs), as compared to the traditional optimal extraction algorithm, which is only correct for a limited class of separable PSFs. The algorithm results in statistically independent extracted samples in the 1D spectrum, and preserves the full native resolution of the 2D spectrograph without degradation. Both the statistical errors and the 1D resolution of the extracted spectrum are accurately determined, allowing a correct χ2 comparison of any model spectrum with the data. Using a model PSF similar to that found in the red channel of the Sloan Digital Sky Survey spectrograph, we compare the performance of our algorithm to that of cross-section based optimal extraction, and also demonstrate that our method allows coaddition and foreground estimation to be carried out as an integral part of the extraction step. This work demonstrates the feasibility of current and next-generation multifiber spectrographs for faint-galaxy surveys even in the presence of strong night-sky foregrounds. We describe the handling of subtleties arising from fiber-to-fiber cross talk, discuss some of the likely challenges in deploying our method to the analysis of a full-scale survey, and note that our algorithm could be generalized into an optimal method for the rectification and combination of astronomical imaging data.
Active noise control: A tutorial for HVAC designers
Energy Technology Data Exchange (ETDEWEB)
Gelin, L.J.
1997-08-01
This article will identify the capabilities and limitations of ANC in its application to HVAC noise control. ANC can be used in ducted HVAC systems to cancel ductborne, low-frequency fan noise by injecting sound waves of equal amplitude and opposite phase into an air duct, as close as possible to the source of the unwanted noise. Destructive interference of the fan noise and injected noise results in sound cancellation. The noise problems that it solves are typically described as rumble, roar or throb, all of which are difficult to address using traditional noise control methods. This article will also contrast the use of active against passive noise control techniques. The main differences between the two noise control measures are acoustic performance, energy consumption, and design flexibility. The article will first present the fundamentals and basic physics of ANC. The application to real HVAC systems will follow.
Combustion and Engine-Core Noise
Ihme, Matthias
2017-01-01
The implementation of advanced low-emission aircraft engine technologies and the reduction of noise from airframe, fan, and jet exhaust have made noise contributions from an engine core increasingly important. Therefore, meeting future ambitious noise-reduction goals requires the consideration of engine-core noise. This article reviews progress on the fundamental understanding, experimental analysis, and modeling of engine-core noise; addresses limitations of current techniques; and identifies opportunities for future research. After identifying core-noise contributions from the combustor, turbomachinery, nozzles, and jet exhaust, they are examined in detail. Contributions from direct combustion noise, originating from unsteady combustion, and indirect combustion noise, resulting from the interaction of flow-field perturbations with mean-flow variations in turbine stages and nozzles, are analyzed. A new indirect noise-source contribution arising from mixture inhomogeneities is identified by extending the theory. Although typically omitted in core-noise analysis, the impact of mean-flow variations and nozzle-upstream perturbations on the jet-noise modulation is examined, providing potential avenues for future core-noise mitigation.
Controlling noise in plasmonic structures with gain
Vyshnevyy, A. A.; Fedyanin, D. Yu.
2017-09-01
Loss compensation by gain medium gives the possibility to exploit subwavelength confinement of light in plasmonic nanostructures and construct nanoscale plasmonic circuits. However, due to fundamentally unavoidable spontaneous emission from the gain medium, lossless waveguides suffer from strong photonic noise, which limits their practical applications. Here we demonstrate the possibility of significant decrease of the noise level while preserving physical dimensions of lossless plasmonic waveguides with gain. Our findings are aimed at extending the communication capabilities of on-chip plasmonic networks.
Sources of noise in Brillouin optical time-domain analyzers
Urricelqui Polvorinos, Javier; Soto, Marcelo A.; Thévenaz, Luc
2015-01-01
This paper presents a thorough study of the different sources of noise affecting Brillouin optical time-domain analyzers (BOTDA), providing a deep insight into the understanding of the fundamental limitations of this kind of sensors. Analytical and experimental results indicate that the noise source ultimately fixing the sensor performance depends basically on the fiber length and the input pump-probe powers. Thus, while the phase-to-intensity noise conversion induced by stimulated Brillouin ...
Ross, Donald
1976-01-01
Mechanics of Underwater Noise elucidates the basic mechanisms by which noise is generated, transmitted by structures and radiated into the sea. Organized into 10 chapters, this book begins with a description of noise, decibels and levels, significance of spectra, and passive sonar equation. Subsequent chapters discuss sound waves in liquids; acoustic radiation fundamentals; wind-generated ocean ambient noise; vibration isolation and structural damping; and radiation by plate flexural vibrations. Other chapters address cavitation, propeller cavitation noise, radiation by fluctuating-force (dipo
Directory of Open Access Journals (Sweden)
Srimant P Tripathy
Full Text Available Correspondence noise is a major factor limiting direction discrimination performance in random-dot kinematograms. In the current study we investigated the influence of correspondence noise on Dmax, which is the upper limit for the spatial displacement of the dots for which coherent motion is still perceived. Human direction discrimination performance was measured, using 2-frame kinematograms having leftward/rightward motion, over a 200-fold range of dot-densities and a four-fold range of dot displacements. From this data Dmax was estimated for the different dot densities tested. A model was proposed to evaluate the correspondence noise in the stimulus. This model summed the outputs of a set of elementary Reichardt-type local detectors that had receptive fields tiling the stimulus and were tuned to the two directions of motion in the stimulus. A key assumption of the model was that the local detectors would have the radius of their catchment areas scaled with the displacement that they were tuned to detect; the scaling factor k linking the radius to the displacement was the only free parameter in the model and a single value of k was used to fit all of the psychophysical data collected. This minimal, correspondence-noise based model was able to account for 91% of the variability in the human performance across all of the conditions tested. The results highlight the importance of correspondence noise in constraining the largest displacement that can be detected.
Guerrero, Pilar
2015-04-02
© 2015, Springer-Verlag Berlin Heidelberg. In this paper we analyse stochastic models of the competition between two resource-limited cell populations which differ in their response to nutrient availability: the resident population exhibits a switch-like response behaviour while the invading population exhibits a bistable response. We investigate how noise in the intracellular regulatory pathways and cell motility influence the fate of the incumbent and invading populations. We focus initially on a spatially homogeneous system and study in detail the role of intracellular noise. We show that in such well-mixed systems, two distinct regimes exist: In the low (intracellular) noise limit, the invader has the ability to invade the resident population, whereas in the high noise regime competition between the two populations is found to be neutral and, in accordance with neutral evolution theory, invasion is a random event. Careful examination of the system dynamics leads us to conclude that (i) even if the invader is unable to invade, the distribution of survival times, PS(t), has a fat-tail behaviour (PS(t)∼t-1) which implies that small colonies of mutants can coexist with the resident population for arbitrarily long times, and (ii) the bistable structure of the invading population increases the stability of the latent population, thus increasing their long-term likelihood of survival, by decreasing the intensity of the noise at the population level. We also examine the effects of spatial inhomogeneity. In the low noise limit we find that cell motility is positively correlated with the aggressiveness of the invader as defined by the time the invader takes to invade the resident population: the faster the invasion, the more aggressive the invader.
Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.
1984-10-19
A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.
Supersonic Jet Noise Reduction Using Microjets
Gutmark, Ephraim; Cuppoletti, Dan; Malla, Bhupatindra
2013-11-01
Fluidic injection for jet noise reduction involves injecting secondary jets into a primary jet to alter the noise characteristics of the primary jet. A major challenge has been determining what mechanisms are responsible for noise reduction due to varying injector designs, injection parameters, and primary jets. The current study provides conclusive results on the effect of injector angle and momentum ux ratio on the acoustics and shock structure of a supersonic Md = 1.56 jet. It is shown that the turbulent mixing noise scales primarily with the injector momentum flux ratio. Increasing the injector momentum flux ratio increases streamwise vorticity generation and reduces peak turbulence levels. It is found that the shock-related noise components are most affected by the interaction of the shocks from the injectors with the primary shock structure of the jet. Increasing momentum flux ratio causes shock noise reduction until a limit where shock noise increases again. It is shown that the shock noise components and mixing noise components are reduced through fundamentally different mechanisms and maximum overall noise reduction is achieved by balancing the reduction of both components.
Analysis of shot noise in the detection of ultrashort optical pulse trains
Quinlan, Franklyn; Jiang, Haifeng; Diddams, Scott A
2013-01-01
We present a frequency domain model of shot noise in the photodetection of ultrashort optical pulse trains using a time-varying analysis. Shot noise-limited photocurrent power spectral densities, signal-to-noise expressions, and shot noise spectral correlations are derived that explicitly include the finite response of the photodetector. It is shown that the strength of the spectral correlations in the shot noise depends on the optical pulse width, and that these correlations can create orders-of-magnitude imbalance between the shot noise-limited amplitude and phase noise of photonically generated microwave carriers. It is also shown that only by accounting for spectral correlations can shot noise be equated with the fundamental quantum limit in the detection of optical pulse-to-pulse timing jitter.
Wide-band CMOS low-noise amplifier exploiting thermal-noise canceling
Bruccoleri, Federico; Klumperink, Eric A.M.; Nauta, Bram
2004-01-01
Known elementary wide-band amplifiers suffer from a fundamental tradeoff between noise figure (NF) and source impedance matching, which limits the NF to values typically above 3 dB. Global negative feedback can be used to break this tradeoff, however, at the price of potential instability. In contra
Noise suppression by quantum control before and after the noise
Wakamura, Hiroaki; Kawakubo, Ryûitirô; Koike, Tatsuhiko
2017-02-01
We discuss the possibility of protecting the state of a quantum system that goes through noise by measurements and operations before and after the noise process. The aim is to seek the optimal protocol that makes the input and output states as close as possible and to clarify the role of the measurements therein. We consider two cases: one can perform quantum measurements and operations (i) only after the noise process and (ii) both before and after. We prove in a two-dimensional Hilbert space that, in case (i), the noise suppression is essentially impossible for all types of noise and, in case (ii), the optimal protocol for the depolarizing noise is either the "do nothing" protocol or the "discriminate and reprepare" protocol. These protocols are not "truly quantum" and can be considered as classical. They involve no measurement or only use the measurement outcomes. These results describe the fundamental limitations in quantum mechanics from the viewpoint of control theory. Finally, we conjecture that a statement similar to case (ii) holds for higher-dimensional Hilbert spaces and present some numerical evidence.
Vilar, J. M. G.; Rubí Capaceti, José Miguel
2001-01-01
We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail.
Singh, Harjit
2011-01-01
""Radiology Fundamentals"" is a concise introduction to the dynamic field of radiology for medical students, non-radiology house staff, physician assistants, nurse practitioners, radiology assistants, and other allied health professionals. The goal of the book is to provide readers with general examples and brief discussions of basic radiographic principles and to serve as a curriculum guide, supplementing a radiology education and providing a solid foundation for further learning. Introductory chapters provide readers with the fundamental scientific concepts underlying the medical use of imag
Zackay, Barak; Ofek, Eran O.
2017-02-01
Image coaddition is one of the most basic operations that astronomers perform. In Paper I, we presented the optimal ways to coadd images in order to detect faint sources and to perform flux measurements under the assumption that the noise is approximately Gaussian. Here, we build on these results and derive from first principles a coaddition technique that is optimal for any hypothesis testing and measurement (e.g., source detection, flux or shape measurements, and star/galaxy separation), in the background-noise-dominated case. This method has several important properties. The pixels of the resulting coadded image are uncorrelated. This image preserves all the information (from the original individual images) on all spatial frequencies. Any hypothesis testing or measurement that can be done on all the individual images simultaneously, can be done on the coadded image without any loss of information. The PSF of this image is typically as narrow, or narrower than the PSF of the best image in the ensemble. Moreover, this image is practically indistinguishable from a regular single image, meaning that any code that measures any property on a regular astronomical image can be applied to it unchanged. In particular, the optimal source detection statistic derived in Paper I is reproduced by matched filtering this image with its own PSF. This coaddition process, which we call proper coaddition, can be understood as the maximum signal-to-noise ratio measurement of the Fourier transform of the image, weighted in such a way that the noise in the entire Fourier domain is of equal variance. This method has important implications for multi-epoch seeing-limited deep surveys, weak lensing galaxy shape measurements, and diffraction-limited imaging via speckle observations. The last topic will be covered in depth in future papers. We provide an implementation of this algorithm in MATLAB.
Energy Technology Data Exchange (ETDEWEB)
Van Aken, B.B.; Veldman, D.; Gouwen, R.J.; Bende, E.E.; Eerenstein, W.
2013-10-15
Damp-heat testing of PV modules is a time-consuming process, taking months. The electrochemical noise (EcN) set-up is a fast, direct corrosion measurement of solar cells, whereby results can be obtained within one hour. EcN measurements are presented for several solar cell concepts and different environments. It correlates with damp-heat degradation involving corrosion, which is rather common in EVA-encapsulated crystalline Si modules. Furthermore, the EcN test can be done as an evaluation tool when probing alternative brands, formulations or processing for metallisation pastes and as a screening test for new batches of metallisation paste.
Zackay, Barak
2015-01-01
Image coaddition is one of the most basic operations that astronomers perform. In Paper~I, we presented the optimal ways to coadd images in order to detect faint sources and to perfrom flux measurements under the assumption that the noise is approximately Gaussian. Here, we build on these results and derive from first principles a coaddition technique which is optimal for any hypothesis testing and measurement (e.g., source detection, flux or shape measurements and star/galaxy separation), in the background-noise-dominated case. This method has several important properties. The pixels of the resulting coadd image are uncorrelated. This image preserves all the information (from the original individual images) on all spatial frequencies. Any hypothesis testing or measurement that can be done on all the individual images simultaneously, can be done on the coadded image without any loss of information. The PSF of this image is typically as narrow, or narrower than the PSF of the best image in the ensemble. Moreov...
Karttunen, Hannu; Oja, Heikki; Poutanen, Markku; Donner, Karl Johan
2007-01-01
Fundamental Astronomy gives a well-balanced and comprehensive introduction to the topics of classical and modern astronomy. While emphasizing both the astronomical concepts and the underlying physical principles, the text provides a sound basis for more profound studies in the astronomical sciences. The fifth edition of this successful undergraduate textbook has been extensively modernized and extended in the parts dealing with the Milky Way, extragalactic astronomy and cosmology as well as with extrasolar planets and the solar system (as a consequence of recent results from satellite missions and the new definition by the International Astronomical Union of planets, dwarf planets and small solar-system bodies). Furthermore a new chapter on astrobiology has been added. Long considered a standard text for physical science majors, Fundamental Astronomy is also an excellent reference and entrée for dedicated amateur astronomers.
Cooper, Beth A.
1995-01-01
NASA Lewis Research Center is home to more than 100 experimental research testing facilities and laboratories, including large wind tunnels and engine test cells, which in combination create a varied and complex noise environment. Much of the equipment was manufactured prior to the enactment of legislation limiting product noise emissions or occupational noise exposure. Routine facility maintenance and associated construction also contributes to a noise exposure management responsibility which is equal in magnitude and scope to that of several small industrial companies. The Noise Program, centrally managed within the Office of Environmental Programs at LRC, maintains overall responsibility for hearing conservation, community noise control, and acoustical and noise control engineering. Centralized management of the LRC Noise Program facilitates the timely development and implementation of engineered noise control solutions for problems identified via either the Hearing Conservation of Community Noise Program. The key element of the Lewis Research Center Noise Program, Acoustical and Noise Control Engineering Services, is focused on developing solutions that permanently reduce employee and community noise exposure and maximize research productivity by reducing or eliminating administrative and operational controls and by improving the safety and comfort of the work environment. The Hearing Conservation Program provides noise exposure assessment, medical monitoring, and training for civil servant and contractor employees. The Community Noise Program aims to maintain the support of LRC's neighboring communities while enabling necessary research operations to accomplish their programmatic goals. Noise control engineering capability resides within the Noise Program. The noise control engineering, based on specific exposure limits, is a fundamental consideration throughout the design phase of new test facilities, labs, and office buildings. In summary, the Noise Program
Fundamentals of differential beamforming
Benesty, Jacob; Pan, Chao
2016-01-01
This book provides a systematic study of the fundamental theory and methods of beamforming with differential microphone arrays (DMAs), or differential beamforming in short. It begins with a brief overview of differential beamforming and some popularly used DMA beampatterns such as the dipole, cardioid, hypercardioid, and supercardioid, before providing essential background knowledge on orthogonal functions and orthogonal polynomials, which form the basis of differential beamforming. From a physical perspective, a DMA of a given order is defined as an array that measures the differential acoustic pressure field of that order; such an array has a beampattern in the form of a polynomial whose degree is equal to the DMA order. Therefore, the fundamental and core problem of differential beamforming boils down to the design of beampatterns with orthogonal polynomials. But certain constraints also have to be considered so that the resulting beamformer does not seriously amplify the sensors’ self noise and the mism...
Ternström, Sten; Södersten, Maria; Bohman, Mikael
2002-06-01
It can be difficult for the voice clinician to observe or measure how a patient uses his voice in a noisy environment. We consider here a novel method for obtaining this information in the laboratory. Worksite noise and filtered white noise were reproduced over high-fidelity loudspeakers. In this noise, 11 subjects read an instructional text of 1.5 to 2 minutes duration, as if addressing a group of people. Using channel estimation techniques, the site noise was suppressed from the recording, and the voice signal alone was recovered. The attainable noise rejection is limited only by the precision of the experimental setup, which includes the need for the subject to remain still so as not to perturb the estimated acoustic channel. This feasibility study, with 7 female and 4 male subjects, showed that small displacements of the speaker's body, even breathing, impose a practical limit on the attainable noise rejection. The noise rejection was typically 30 dB and maximally 40 dB down over the entire voice spectrum. Recordings thus processed were clean enough to permit voice analysis with the long-time average spectrum and the computerized phonetogram. The effects of site noise on voice sound pressure level, fundamental frequency, long-term average spectrum centroid, phonetogram area, and phonation time were much as expected, but with some interesting differences between females and males.
Redmond, W H
2001-01-01
This chapter outlines current marketing practice from a managerial perspective. The role of marketing within an organization is discussed in relation to efficiency and adaptation to changing environments. Fundamental terms and concepts are presented in an applied context. The implementation of marketing plans is organized around the four P's of marketing: product (or service), promotion (including advertising), place of delivery, and pricing. These are the tools with which marketers seek to better serve their clients and form the basis for competing with other organizations. Basic concepts of strategic relationship management are outlined. Lastly, alternate viewpoints on the role of advertising in healthcare markets are examined.
Sagaidachnyi, A. A.; Volkov, I. U.; Fomin, A. V.
2016-04-01
This paper describes limit possibilities of modern cooled thermal imaging cameras as a tool for estimation of blood flow oscillations at the surface of living body. Skin temperature oscillations, as we assumed, are a consequence of the blood flow oscillations. We considered the temperature sensitivity 0.01-0.02 °C as a typical for the most of modern cooled long wave thermal imaging cameras. Fourier filter used to investigate the temperature signal separately within endothelial, neurogenic, myogenic, respiratory and cardiac frequency ranges. The level of temporal noise has been estimated during measurements of no living body with stabilized temperature ~ 24°C. The level of temperature oscillations has been calculated for the group of healthy subjects within each frequency range. Thus, we were able to determine signal-to-noise ratio within frequency band [0.001, 1] Hz. As a result, we determine that skin temperature oscillations measured by thermal imaging camera with sensitivity 0.02°C have the upper frequency limit ~ 0.2 Hz. In other words, within the respiratory and cardiac frequency ranges of blood flow oscillations the noise level exceeds signal one, and temperature measurements at the skin surface are practically useless. The endothelial, neurogenic and myogenic components of the temperature oscillations contain ~98% of the total spectral power of the signal. We have plot the empirical extrapolated curve of sensitivity of thermal imaging camera vs. frequency of the temperature oscillations. The data analysis shows that measurements of skin temperature oscillations within respiratory and cardiac ranges require the temperature sensitivity at least ~ 0.01°C and 0.001°C, respectively.
Energy Technology Data Exchange (ETDEWEB)
Ramos, D [BioNanoMechanics Lab, National Centre for Microelectronics, IMM-CNM, CSIC Isaac Newton 8 (PTM), Tres Cantos E-28760, Madrid (Spain); Tamayo, J [BioNanoMechanics Lab, National Centre for Microelectronics, IMM-CNM, CSIC Isaac Newton 8 (PTM), Tres Cantos E-28760, Madrid (Spain); Mertens, J [BioNanoMechanics Lab, National Centre for Microelectronics, IMM-CNM, CSIC Isaac Newton 8 (PTM), Tres Cantos E-28760, Madrid (Spain); Calleja, M [BioNanoMechanics Lab, National Centre for Microelectronics, IMM-CNM, CSIC Isaac Newton 8 (PTM), Tres Cantos E-28760, Madrid (Spain); Villanueva, L G [STI-IMM-LMIS1, EPFL-Station 17, CH-1015, Lausanne (Switzerland); Zaballos, A [Genomics Functional Unit, Department of Immunology and Oncology, CNB-CSIC, Darwin 3, Madrid E-28049 (Spain)
2008-01-23
We have measured the effect of bacteria adsorption on the resonant frequency of microcantilevers as a function of the adsorption position and vibration mode. The resonant frequencies were measured from the Brownian fluctuations of the cantilever tip. We found that the sign and amount of the resonant frequency change is determined by the position and extent of the adsorption on the cantilever with regard to the shape of the vibration mode. To explain these results, a theoretical one-dimensional model is proposed. We obtain analytical expressions for the resonant frequency that accurately fit the data obtained by the finite element method. More importantly, the theory data shows a good agreement with the experiments. Our results indicate that there exist two opposite mechanisms that can produce a significant resonant frequency shift: the stiffness and the mass of the bacterial cells. Based on the thermomechanical noise, we analyse the regions of the cantilever of lowest and highest sensitivity to the attachment of bacteria. The combination of high vibration modes and the confinement of the adsorption to defined regions of the cantilever allows the detection of single bacterial cells by only measuring the Brownian fluctuations. This study can be extended to smaller cantilevers and other biological systems such as proteins and nucleic acids.
Truong, Gar-Wing; May, Eric F; Stace, Thomas M; Luiten, Andre N
2015-01-01
Spectroscopy has an illustrious history delivering serendipitous discoveries and providing a stringent testbed for new physical predictions, including applications from trace materials detection, to understanding the atmospheres of stars and planets, and even constraining cosmological models. Reaching fundamental-noise limits permits optimal extraction of spectroscopic information from an absorption measurement. Here we demonstrate a quantum-limited spectrometer that delivers high-precision measurements of the absorption lineshape. These measurements yield a ten-fold improvement in the accuracy of the excited-state (6P$_{1/2}$) hyperfine splitting in Cs, and reveals a breakdown in the well-known Voigt spectral profile. We develop a theoretical model that accounts for this breakdown, explaining the observations to within the shot-noise limit. Our model enables us to infer the thermal velocity-dispersion of the Cs vapour with an uncertainty of 35ppm within an hour. This allows us to determine a value for Boltzm...
Noise of quantum solitons and their quasi-coherent states
Institute of Scientific and Technical Information of China (English)
段路明; 郭光灿
1997-01-01
Quantum noise of optical solitons is analysed based on the exact solutions of the quantum nonlinear Schrodmger equation (QNSE) and the construction of the quantum soliton states. The noise limits are obtained for the local photon number and for the local quadrature phase amplitude. They are larger than the vacuum fluctuation. So in the fundamental soliton states the variance of the local photon number and the local quadrature phase amplitude cannot be squeezed The sohton states with the minimum noise are quasi-coherent states, in which the quantum dispersion effects are negligible.
Directory of Open Access Journals (Sweden)
S. Coburn
2011-11-01
Full Text Available We designed and assembled the University of Colorado Ground Multi AXis Differential Optical Absorption Spectroscopy (CU GMAX-DOAS instrument to retrieve bromine oxide (BrO, iodine oxide (IO, formaldehyde (HCHO, glyoxal (CHOCHO, nitrogen dioxide (NO_{2} and the oxygen dimer (O_{4} in the coastal atmosphere of the Gulf of Mexico. The detection sensitivity of DOAS measurements is proportional to the root mean square (RMS of the residual spectrum that remains after all absorbers have been subtracted. Here we describe the CU GMAX-DOAS instrument and demonstrate that the hardware is capable of attaining RMS of ∼6 × 10^{−6} from solar stray light noise tests using high photon count spectra (compatible within a factor of two with photon shot noise.
Laboratory tests revealed two critical instrument properties that, in practice, can limit the RMS: (1 detector non-linearity noise, RMS_{NLin}, and (2 temperature fluctuations that cause variations in optical resolution (full width at half the maximum, FWHM, of atomic emission lines and give rise to optical resolution noise, RMS_{FWHM}. The non-linearity of our detector is low (∼10^{−2} yet – unless actively controlled – is sufficiently large to create RMS_{NLin} of up to 2 × 10^{−4}. The optical resolution is sensitive to temperature changes (0.03 detector pixels °C^{−1} at 334 nm, and temperature variations of 0.1°C can cause RMS_{FWHM} of ~1 × 10^{−4}. Both factors were actively addressed in the design of the CU GMAX-DOAS instrument. With an integration time of 60 s the instrument can reach RMS noise of 3 × 10^{−5}, and typical RMS in field measurements ranged from 6 × 10^{−5} to 1.4 × 10^{−4}.
The CU GMAX-DOAS was set up at a coastal site near Pensacola, Florida, where we detected BrO, IO and CHOCHO in the marine boundary layer (MBL, with daytime
Coburn, S.; Dix, B.; Sinreich, R.; Volkamer, R.
2011-11-01
We designed and assembled the University of Colorado Ground Multi AXis Differential Optical Absorption Spectroscopy (CU GMAX-DOAS) instrument to retrieve bromine oxide (BrO), iodine oxide (IO), formaldehyde (HCHO), glyoxal (CHOCHO), nitrogen dioxide (NO2) and the oxygen dimer (O4) in the coastal atmosphere of the Gulf of Mexico. The detection sensitivity of DOAS measurements is proportional to the root mean square (RMS) of the residual spectrum that remains after all absorbers have been subtracted. Here we describe the CU GMAX-DOAS instrument and demonstrate that the hardware is capable of attaining RMS of ∼6 × 10-6 from solar stray light noise tests using high photon count spectra (compatible within a factor of two with photon shot noise). Laboratory tests revealed two critical instrument properties that, in practice, can limit the RMS: (1) detector non-linearity noise, RMSNLin, and (2) temperature fluctuations that cause variations in optical resolution (full width at half the maximum, FWHM, of atomic emission lines) and give rise to optical resolution noise, RMSFWHM. The non-linearity of our detector is low (∼10-2) yet - unless actively controlled - is sufficiently large to create RMSNLin of up to 2 × 10-4. The optical resolution is sensitive to temperature changes (0.03 detector pixels °C-1 at 334 nm), and temperature variations of 0.1°C can cause RMSFWHM of ~1 × 10-4. Both factors were actively addressed in the design of the CU GMAX-DOAS instrument. With an integration time of 60 s the instrument can reach RMS noise of 3 × 10-5, and typical RMS in field measurements ranged from 6 × 10-5 to 1.4 × 10-4. The CU GMAX-DOAS was set up at a coastal site near Pensacola, Florida, where we detected BrO, IO and CHOCHO in the marine boundary layer (MBL), with daytime average tropospheric vertical column densities (average of data above the detection limit), VCDs, of ∼2 × 1013 molec cm-2, 8 × 1012 molec cm-2 and 4 × 1014 molec cm-2, respectively. HCHO and
Hybrid colored noise process with space-dependent switching rates
Bressloff, Paul C.; Lawley, Sean D.
2017-07-01
A fundamental issue in the theory of continuous stochastic process is the interpretation of multiplicative white noise, which is often referred to as the Itô-Stratonovich dilemma. From a physical perspective, this reflects the need to introduce additional constraints in order to specify the nature of the noise, whereas from a mathematical perspective it reflects an ambiguity in the formulation of stochastic differential equations (SDEs). Recently, we have identified a mechanism for obtaining an Itô SDE based on a form of temporal disorder. Motivated by switching processes in molecular biology, we considered a Brownian particle that randomly switches between two distinct conformational states with different diffusivities. In each state, the particle undergoes normal diffusion (additive noise) so there is no ambiguity in the interpretation of the noise. However, if the switching rates depend on position, then in the fast switching limit one obtains Brownian motion with a space-dependent diffusivity of the Itô form. In this paper, we extend our theory to include colored additive noise. We show that the nature of the effective multiplicative noise process obtained by taking both the white-noise limit (κ →0 ) and fast switching limit (ɛ →0 ) depends on the order the two limits are taken. If the white-noise limit is taken first, then we obtain Itô, and if the fast switching limit is taken first, then we obtain Stratonovich. Moreover, the form of the effective diffusion coefficient differs in the two cases. The latter result holds even in the case of space-independent transition rates, where one obtains additive noise processes with different diffusion coefficients. Finally, we show that yet another form of multiplicative noise is obtained in the simultaneous limit ɛ ,κ →0 with ɛ /κ2 fixed.
Quantum-Noise-Limited Sensitivity-Enhancement of a Passive Optical Cavity by a Fast-Light Medium
Smith, David D.; Luckay, H. A.; Chang, Hongrok; Myneni, Krishna
2016-01-01
We demonstrate for a passive optical cavity containing an intracavity dispersive atomic medium, the increase in scale factor near the critical anomalous dispersion is not cancelled by mode broadening or attenuation, resulting in an overall increase in the predicted quantum-noiselimited sensitivity. Enhancements of over two orders of magnitude are measured in the scale factor, which translates to greater than an order-of-magnitude enhancement in the predicted quantumnoise- limited measurement precision, by temperature tuning a low-pressure vapor of noninteracting atoms in a low-finesse cavity close to the critical anomalous dispersion condition. The predicted enhancement in sensitivity is confirmed through Monte-Carlo numerical simulations.
Crouch, Ashley D
2012-01-01
We investigate how the azimuthal ambiguity in solar vector magnetogram data can be resolved by using the divergence-free property of magnetic fields. In a previous article, by Crouch, Barnes, and Leka (Solar Phys. 260, 271, 2009), error-free synthetic data were used to test several methods that each make a different assumption about how the divergence-free property can be used to resolve the ambiguity. In this paper this testing is continued with an examination of the effects of Poisson photon noise and limited instrumental spatial resolution. We find that all currently available methods based on the divergence-free property can produce undesirable results when photon noise or unresolved structure are present in the data. We perform a series of experiments aimed at improving the performance of the global minimisation method, which is the most promising of the methods. We present a two-step approach that produces reasonable results in tests using synthetic data. The first step of this approach involves the glo...
Sub-Shot-Noise Magnetometry with a Correlated Spin-Relaxation Dominated Alkali-Metal Vapor
Kominis, I. K.
2007-01-01
Spin noise sets fundamental limits to the precision of measurements using spin-polarized atomic vapors, such as performed with sensitive atomic magnetometers. Spin squeezing offers the possibility to extend the measurement precision beyond the standard quantum limit of uncorrelated atoms. Contrary to the current understanding, we show that even in the presence of spin relaxation, spin squeezing can lead to a significant reduction of spin noise, and hence an increase in magnetometric sensitivi...
Kutsch, Werner Leo
2016-04-01
Nowadays,technical possibilities in Earth Observation provide enormous amounts of data that open great possibilities to review existing ecological theories and develop new ones. Several examples for that are shown in the presentation in order to discuss potentials and limitations of the underlying concepts and provide feedback to large infrastructures carrying out ecological observations or experiments. Since different ecological questions or theoretical approaches require different methods, data interoperability and co-location are practical challenges. Nevertheless, we also have to learn that not every method is applicable in all ecosystems and that data have to be critically scrutinized before being sure that we can really draw ecological conclusions. This is time consuming and very often frustrating since we may learn that we have sometimes invested lots of work and money for building infrastructure at a site that is not suitable for the method.
DeForest, Craig; Seaton, Daniel B.; Darnell, John A.
2017-08-01
I present and demonstrate a new, general purpose post-processing technique, "3D noise gating", that can reduce image noise by an order of magnitude or more without effective loss of spatial or temporal resolution in typical solar applications.Nearly all scientific images are, ultimately, limited by noise. Noise can be direct Poisson "shot noise" from photon counting effects, or introduced by other means such as detector read noise. Noise is typically represented as a random variable (perhaps with location- or image-dependent characteristics) that is sampled once per pixel or once per resolution element of an image sequence. Noise limits many aspects of image analysis, including photometry, spatiotemporal resolution, feature identification, morphology extraction, and background modeling and separation.Identifying and separating noise from image signal is difficult. The common practice of blurring in space and/or time works because most image "signal" is concentrated in the low Fourier components of an image, while noise is evenly distributed. Blurring in space and/or time attenuates the high spatial and temporal frequencies, reducing noise at the expense of also attenuating image detail. Noise-gating exploits the same property -- "coherence" -- that we use to identify features in images, to separate image features from noise.Processing image sequences through 3-D noise gating results in spectacular (more than 10x) improvements in signal-to-noise ratio, while not blurring bright, resolved features in either space or time. This improves most types of image analysis, including feature identification, time sequence extraction, absolute and relative photometry (including differential emission measure analysis), feature tracking, computer vision, correlation tracking, background modeling, cross-scale analysis, visual display/presentation, and image compression.I will introduce noise gating, describe the method, and show examples from several instruments (including SDO
Zero Thermal Noise in Resistors at Zero Temperature
Kish, Laszlo B.; Niklasson, Gunnar A.; Granqvist, Claes-Göran
2016-06-01
The bandwidth of transistors in logic devices approaches the quantum limit, where Johnson noise and associated error rates are supposed to be strongly enhanced. However, the related theory — asserting a temperature-independent quantum zero-point (ZP) contribution to Johnson noise, which dominates the quantum regime — is controversial and resolution of the controversy is essential to determine the real error rate and fundamental energy dissipation limits of logic gates in the quantum limit. The Callen-Welton formula (fluctuation-dissipation theorem) of voltage and current noise for a resistance is the sum of Nyquist’s classical Johnson noise equation and a quantum ZP term with a power density spectrum proportional to frequency and independent of temperature. The classical Johnson-Nyquist formula vanishes at the approach of zero temperature, but the quantum ZP term still predicts non-zero noise voltage and current. Here, we show that this noise cannot be reconciled with the Fermi-Dirac distribution, which defines the thermodynamics of electrons according to quantum-statistical physics. Consequently, Johnson noise must be nil at zero temperature, and non-zero noise found for certain experimental arrangements may be a measurement artifact, such as the one mentioned in Kleen’s uncertainty relation argument.
Noise analysis and measurement of time delay and integration charge coupled device
Institute of Scientific and Technical Information of China (English)
Wang De-Jiang; Zhang Tao
2011-01-01
Time delay and integration(TDI)charge coupled device(CCD)noise sets a fundamental limit on image sensor performance,especially under low illumination in remote sensing applications.After introducing the complete sources of CCD noise,we study the effects of TDI operation mode on noise,and the relationship between different types of noise and number of the TDI stage.Then we propose a new technique to identify and measure sources of TDI CCD noise employing mathematical statistics theory,where theoretical analysis shows that noise estimated formulation converges well.Finally,we establish a testing platform to carry out experiments,and a standard TDI CCD is calibrated by using the proposed method.The experimental results show that the noise analysis and measurement methods presented in this paper are useful for modeling TDI CCDs.
Energy Technology Data Exchange (ETDEWEB)
Wollaber, Allan Benton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-06-16
This is a powerpoint presentation which serves as lecture material for the Parallel Computing summer school. It goes over the fundamentals of the Monte Carlo calculation method. The material is presented according to the following outline: Introduction (background, a simple example: estimating π), Why does this even work? (The Law of Large Numbers, The Central Limit Theorem), How to sample (inverse transform sampling, rejection), and An example from particle transport.
Directory of Open Access Journals (Sweden)
Luís Paulo Piassi
2011-01-01
Full Text Available O objetivo deste trabalho, partindo das considerações sobre cidadania e inclusão apresentadas nos Parâmetros Curriculares Nacionais para o ensino de ciências, é trazer uma reflexão de tais conceitos em função de referenciais teóricos das pedagogias críticas e de estudos acadêmicos no ambiente escolar. O que se pretende mostrar são os limites relativamente estreitos das concepções apresentadas nesses documentos curriculares, concepções, muitas vezes, aceitas como guia para a transformação do ensino de ciências na direção dos interesses socioculturais dos estudantes. Partindo disso, e considerando estudos acadêmicos realizados em ambiente escolar, procuramos mostrar que a universidade pode ter um papel mais relevante na proposição de mudanças curriculares mais efetivas no sentido de atender às demandas sociais.
Quantum-limited amplification via reservoir engineering.
Metelmann, A; Clerk, A A
2014-04-04
We describe a new kind of phase-preserving quantum amplifier which utilizes dissipative interactions in a parametrically coupled three-mode bosonic system. The use of dissipative interactions provides a fundamental advantage over standard cavity-based parametric amplifiers: large photon number gains are possible with quantum-limited added noise, with no limitation on the gain-bandwidth product. We show that the scheme is simple enough to be implemented both in optomechanical systems and in superconducting microwave circuits.
Quantum-Limited Amplification via Reservoir Engineering
Metelmann, A.; Clerk, A. A.
2013-01-01
We describe a new kind of phase-preserving quantum amplifier which utilizes dissipative interactions in a parametrically-coupled three-mode bosonic system. The use of dissipative interactions provides a fundamental advantage over standard cavity-based parametric amplifiers: large photon number gains are possible with quantum-limited added noise, with no limitation on the gain-bandwidth product. We show that the scheme is simple enough to be implemented both in optomechanical systems and in su...
Intrinsic noise sources in superconductors near the transition temperature
Energy Technology Data Exchange (ETDEWEB)
Galeazzi, M. E-mail: galeazzi@physics.miami.edu; Zuo, F.; Chen, C.; Ursino, E
2004-03-11
The performance of Transition Edge Sensors (TES) is limited by excess noise that is not predicted by the current theory of microcalorimeters and bolometers. The nature of this noise is currently unknown, but is likely to be dominated by fundamental physics of supeconductors. The University of Miami has recently started a joint effort between the microcalorimeter group and the superconductivity group to study and characterize the noise in TES. In particular, we plan to investigate the effect of flux motion due to self-field and external field and the effect of fluctuating order parameter by measuring the para-conductivity due to fluctuations in the number of Cooper pairs near the transition. We also plan to characterize the fundamental physical parameters of the TES to better predict their properties. In this paper we report our preliminary qualitative assessment of the problem, based on the literature, and we illustrate the experimental techniques that we plan to use for the investigation.
Fundamental composite electroweak dynamics
DEFF Research Database (Denmark)
Arbey, Alexandre; Cacciapaglia, Giacomo; Cai, Haiying
2017-01-01
Using the recent joint results from the ATLAS and CMS collaborations on the Higgs boson, we determine the current status of composite electroweak dynamics models based on the expected scalar sector. Our analysis can be used as a minimal template for a wider class of models between the two limiting...... cases of composite Goldstone Higgs and Technicolor-like ones. This is possible due to the existence of a unified description, both at the effective and fundamental Lagrangian levels, of models of composite Higgs dynamics where the Higgs boson itself can emerge, depending on the way the electroweak...... space at the effective Lagrangian level. We show that a wide class of models of fundamental composite electroweak dynamics are still compatible with the present constraints. The results are relevant for the ongoing and future searches at the Large Hadron Collider....
Helicopter Noise And Noise Abatement Procedures
Directory of Open Access Journals (Sweden)
Borivoj Galović
2004-03-01
Full Text Available The helicopter generated noise at and around the airports islower than the noise generated by aeroplanes, since their numberof operations, i. e. the number of takeoffs and landings ismuch lower than the takeoffs and landings of the aeroplanes.Out of some hundred operations a day, helicopters participatewith approximately 15%, but the very impact of noise is by nomeans negligible, since the number of helicopter flights aboveurban areas is constantly increasing.This paper attempts to analyse this phenomenon and thetype of helicopter generated noise, its negative impacts, to explainthe flight procedures and the operative procedures duringtakeoff, landing and overflight of helicopters in operations inthe vicinity and outside airports, as well as the methods of measuringand determining the limit of noise [eve~ and the resultingproblems.
Limitations on quantum key repeaters.
Bäuml, Stefan; Christandl, Matthias; Horodecki, Karol; Winter, Andreas
2015-04-23
A major application of quantum communication is the distribution of entangled particles for use in quantum key distribution. Owing to noise in the communication line, quantum key distribution is, in practice, limited to a distance of a few hundred kilometres, and can only be extended to longer distances by use of a quantum repeater, a device that performs entanglement distillation and quantum teleportation. The existence of noisy entangled states that are undistillable but nevertheless useful for quantum key distribution raises the question of the feasibility of a quantum key repeater, which would work beyond the limits of entanglement distillation, hence possibly tolerating higher noise levels than existing protocols. Here we exhibit fundamental limits on such a device in the form of bounds on the rate at which it may extract secure key. As a consequence, we give examples of states suitable for quantum key distribution but unsuitable for the most general quantum key repeater protocol.
Fundamental Limits to Extinction by Metallic Nanoparticles
2014-03-28
of the boundary-element method [44]. Angle averaging is essen- tially free with such a solver. In many applications, the figure PRL 112, 123903 (2014...the charge density on resonance, where ϵAgð437 nmÞ ≈ −5.5þ 0.7i. Particle dimensions are ≈10 nm. PRL 112, 123903 (2014) P HY S I CA L R EV I EW LE T T...predicts σext ∼ λ2 scaling only when radiation loss dominates over absorption loss; when PRL 112, 123903 (2014) P HY S I CA L R EV I EW LE T T ER S week
Landing gear noise attenuation
Moe, Jeffrey W. (Inventor); Whitmire, Julia (Inventor); Kwan, Hwa-Wan (Inventor); Abeysinghe, Amal (Inventor)
2011-01-01
A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.
Energy Technology Data Exchange (ETDEWEB)
Maschke, C. [Technische Univ. Berlin (Germany). Inst. fuer Technische Akustik; Ising, H. [Umweltbundesamt, Berlin (Germany). Inst. fuer Wasser-, Boden- und Lufthygiene; Hecht, K. [Inst. fuer Stressforschung, Berlin (Germany)
1997-03-01
In part 2 of the review, an evaluation is given from the angle of prophylactic medicine, of the results of several experimental and epidemiologic studies on the excretion of stress hormones induced by nocturnal traffic noise. (orig./MG) [Deutsch] In Teil 2 der Uebersichtsarbeit werden Ergebnisse mehrerer experimenteller und epidemiologischer Studien ueber die Stresshormonausscheidung bei naechtlichem Verkehrslaerm vorgestellt und praeventivmedizinisch bewertet. (orig./MG)
Twin Matter Waves for Interferometry Beyond the Classical Limit
DEFF Research Database (Denmark)
Lücke, Bernd; Scherer, Manuel; Kruse, Jens;
2011-01-01
Interferometers with atomic ensembles constitute an integral part of modern precision metrology. However, these interferometers are fundamentally restricted by the shot noise limit, which can only be overcome by creating quantum entanglement among the atoms. We used spin dynamics in Bose-Einstein...
Institute of Scientific and Technical Information of China (English)
肖慧慧; 王超; 徐肖豪
2011-01-01
The shortcomings of current airport noise evaluation parameters, which include weighted equivalent continuous perceived noise level (WECPNL), are analyzed.According to the above analysis, equivalent sound level Leq and sound exposure level (SEL) are proposed as the new airport noise evaluation parameters.Annoyance and sleep disturbance caused by the aircraft noise are analyzed in detail.And the limitation values of corresponding noise evaluation parameters are suggested.%对计权等效连续感觉噪声级WECPNL作为机场噪声评价量的不足进行分析,并以此为基础提出采用等效声级Leq和声暴露级SEL两个参量作为机场噪声的评价量.从飞机噪声引起的主观烦恼度和对睡眠的干扰两个方面进行深入分析,并提出相应评价量的限制标准建议值.
Thermal and Quantum Mechanical Noise of a Superfluid Gyroscope
Chui, Talso; Penanen, Konstantin
2004-01-01
A potential application of a superfluid gyroscope is for real-time measurements of the small variations in the rotational speed of the Earth, the Moon, and Mars. Such rotational jitter, if not measured and corrected for, will be a limiting factor on the resolution potential of a GPS system. This limitation will prevent many automation concepts in navigation, construction, and biomedical examination from being realized. We present the calculation of thermal and quantum-mechanical phase noise across the Josephson junction of a superfluid gyroscope. This allows us to derive the fundamental limits on the performance of a superfluid gyroscope. We show that the fundamental limit on real-time GPS due to rotational jitter can be reduced to well below 1 millimeter/day. Other limitations and their potential mitigation will also be discussed.
Genetic noise control via protein oligomerization
Energy Technology Data Exchange (ETDEWEB)
Ghim, C; Almaas, E
2008-06-12
Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamical role of protein-protein associations. We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch), integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast protein binding-unbinding kinetics, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its intrinsic switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced) state from randomly being induced (uninduced). The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of phenotypically important toggle switches, and nested positive feedback loops in
Calculation of mutual information for nonlinear communication channel at large signal-to-noise ratio
Terekhov, I. S.; Reznichenko, A. V.; Turitsyn, S. K.
2016-10-01
Using the path-integral technique we examine the mutual information for the communication channel modeled by the nonlinear Schrödinger equation with additive Gaussian noise. The nonlinear Schrödinger equation is one of the fundamental models in nonlinear physics, and it has a broad range of applications, including fiber optical communications—the backbone of the internet. At large signal-to-noise ratio we present the mutual information through the path-integral, which is convenient for the perturbative expansion in nonlinearity. In the limit of small noise and small nonlinearity we derive analytically the first nonzero nonlinear correction to the mutual information for the channel.
Directory of Open Access Journals (Sweden)
Duane Knudson
2007-09-01
Full Text Available DESCRIPTION This book provides a broad and in-depth theoretical and practical description of the fundamental concepts in understanding biomechanics in the qualitative analysis of human movement. PURPOSE The aim is to bring together up-to-date biomechanical knowledge with expert application knowledge. Extensive referencing for students is also provided. FEATURES This textbook is divided into 12 chapters within four parts, including a lab activities section at the end. The division is as follows: Part 1 Introduction: 1.Introduction to biomechanics of human movement; 2.Fundamentals of biomechanics and qualitative analysis; Part 2 Biological/Structural Bases: 3.Anatomical description and its limitations; 4.Mechanics of the musculoskeletal system; Part 3 Mechanical Bases: 5.Linear and angular kinematics; 6.Linear kinetics; 7.Angular kinetics; 8.Fluid mechanics; Part 4 Application of Biomechanics in Qualitative Analysis :9.Applying biomechanics in physical education; 10.Applying biomechanics in coaching; 11.Applying biomechanics in strength and conditioning; 12.Applying biomechanics in sports medicine and rehabilitation. AUDIENCE This is an important reading for both student and educators in the medicine, sport and exercise-related fields. For the researcher and lecturer it would be a helpful guide to plan and prepare more detailed experimental designs or lecture and/or laboratory classes in exercise and sport biomechanics. ASSESSMENT The text provides a constructive fundamental resource for biomechanics, exercise and sport-related students, teachers and researchers as well as anyone interested in understanding motion. It is also very useful since being clearly written and presenting several ways of examples of the application of biomechanics to help teach and apply biomechanical variables and concepts, including sport-related ones
Tokuhisa, Atsushi; Taka, Junichiro; Kono, Hidetoshi; Go, Nobuhiro
2012-01-01
A new two-step algorithm is developed for reconstructing the three-dimensional diffraction intensity of a globular biological macromolecule from many experimentally measured quantum-noise-limited two-dimensional X-ray laser diffraction patterns, each for an unknown orientation. The first step is classification of the two-dimensional patterns into groups according to the similarity of direction of the incident X-rays with respect to the molecule and an averaging within each group to reduce the noise. The second step is detection of common intersecting circles between the signal-enhanced two-dimensional patterns to identify their mutual location in the three-dimensional wavenumber space. The newly developed algorithm enables one to detect a signal for classification in noisy experimental photon-count data with as low as ∼0.1 photons per effective pixel. The wavenumber of such a limiting pixel determines the attainable structural resolution. From this fact, the resolution limit due to the quantum noise attainable by this new method of analysis as well as two important experimental parameters, the number of two-dimensional patterns to be measured (the load for the detector) and the number of pairs of two-dimensional patterns to be analysed (the load for the computer), are derived as a function of the incident X-ray intensity and quantities characterizing the target molecule. PMID:22514069
Sensitivity Limitations for Multivariable Linear Filtering
Directory of Open Access Journals (Sweden)
Steven R. Weller
2007-01-01
Full Text Available This paper examines fundamental limitations in performance which apply to linear filtering problems associated with multivariable systems having as many inputs as outputs. The results of this paper quantify unavoidable limitations in the sensitivity of state estimates to process and measurement disturbances, as represented by the maximum singular values of the relevant transfer matrices. These limitations result from interpolation constraints imposed by open right half-plane poles and zeros in the transfer matrices linking process noise and output noise with state estimates. Using the Poisson integral inequality, this paper shows how sensitivity limitations and tradeoffs in multivariable filtering problems are intimately related to the directionality properties of the open right half-plane poles and zeros in these transfer matrices.
Noise and Neuronal Heterogeneity
Barber, Michael J
2010-01-01
We consider signal transaction in a simple neuronal model featuring intrinsic noise. The presence of noise limits the precision of neural responses and impacts the quality of neural signal transduction. We assess the signal transduction quality in relation to the level of noise, and show it to be maximized by a non-zero level of noise, analogous to the stochastic resonance effect. The quality enhancement occurs for a finite range of stimuli to a single neuron; we show how to construct networks of neurons that extend the range. The range increases more rapidly with network size when we make use of heterogeneous populations of neurons with a variety of thresholds, rather than homogeneous populations of neurons all with the same threshold. The limited precision of neural responses thus can have a direct effect on the optimal network structure, with diverse functional properties of the constituent neurons supporting an economical information processing strategy that reduces the metabolic costs of handling a broad...
Noise characteristics of thermistors: Measurement methods and results of selected devices
Ryger, Ivan; Harber, Dave; Stephens, Michelle; White, Malcolm; Tomlin, Nathan; Spidell, Matthew; Lehman, John
2017-02-01
As part of the development of a spectrally uniform room-temperature absolute radiometer, we have studied the electrical noise of several bulk chip thermistors in order to estimate the noise floor and optical dynamic range. Understanding the fundamental limits of the temperature sensitivity leads inevitably to studying the noise background of the complex electro-thermal system. To this end, we employ a measurement technique based on alternating current synchronous demodulation. Results of our analysis show that the combination of a low-current noise Junction Field Effect Transistor (JFET) preamplifier together with chip thermistors is optimal for our purpose, yielding a root mean square noise temperature of 2.8 μK in the frequency range of 0.01 Hz to 1 Hz.
Exchange Rates and Fundamentals.
Engel, Charles; West, Kenneth D.
2005-01-01
We show analytically that in a rational expectations present-value model, an asset price manifests near-random walk behavior if fundamentals are I (1) and the factor for discounting future fundamentals is near one. We argue that this result helps explain the well-known puzzle that fundamental variables such as relative money supplies, outputs,…
Airframe-Jet Engine Integration Noise
Tam, Christopher; Antcliff, Richard R. (Technical Monitor)
2003-01-01
It has been found experimentally that the noise radiated by a jet mounted under the wing of an aircraft exceeds that of the same jet in a stand-alone environment. The increase in noise is referred to as jet engine airframe integration noise. The objectives of the present investigation are, (1) To obtain a better understanding of the physical mechanisms responsible for jet engine airframe integration noise or installation noise. (2) To develop a prediction model for jet engine airframe integration noise. It is known that jet mixing noise consists of two principal components. They are the noise from the large turbulence structures of the jet flow and the noise from the fine scale turbulence. In this investigation, only the effect of jet engine airframe interaction on the fine scale turbulence noise of a jet is studied. The fine scale turbulence noise is the dominant noise component in the sideline direction. Thus we limit out consideration primarily to the sideline.
Testing Our Fundamental Assumptions
Kohler, Susanna
2016-06-01
fundamental assumptions.A recent focus set in the Astrophysical Journal Letters, titled Focus on Exploring Fundamental Physics with Extragalactic Transients, consists of multiple published studies doing just that.Testing General RelativitySeveral of the articles focus on the 4th point above. By assuming that the delay in photon arrival times is only due to the gravitational potential of the Milky Way, these studies set constraints on the deviation of our galaxys gravitational potential from what GR would predict. The study by He Gao et al. uses the different photon arrival times from gamma-ray bursts to set constraints at eVGeV energies, and the study by Jun-Jie Wei et al. complements this by setting constraints at keV-TeV energies using photons from high-energy blazar emission.Photons or neutrinos from different extragalactic transients each set different upper limits on delta gamma, the post-Newtonian parameter, vs. particle energy or frequency. This is a test of Einsteins equivalence principle: if the principle is correct, delta gamma would be exactly zero, meaning that photons of different energies move at the same velocity through a vacuum. [Tingay Kaplan 2016]S.J. Tingay D.L. Kaplan make the case that measuring the time delay of photons from fast radio bursts (FRBs; transient radio pulses that last only a few milliseconds) will provide even tighter constraints if we are able to accurately determine distances to these FRBs.And Adi Musser argues that the large-scale structure of the universe plays an even greater role than the Milky Way gravitational potential, allowing for even stricter testing of Einsteins equivalence principle.The ever-narrower constraints from these studies all support GR as a correct set of rules through which to interpret our universe.Other Tests of Fundamental PhysicsIn addition to the above tests, Xue-Feng Wu et al. show that FRBs can be used to provide severe constraints on the rest mass of the photon, and S. Croft et al. even touches on what we
The fundamentals of mathematical analysis
Fikhtengol'ts, G M
1965-01-01
The Fundamentals of Mathematical Analysis, Volume 1 is a textbook that provides a systematic and rigorous treatment of the fundamentals of mathematical analysis. Emphasis is placed on the concept of limit which plays a principal role in mathematical analysis. Examples of the application of mathematical analysis to geometry, mechanics, physics, and engineering are given. This volume is comprised of 14 chapters and begins with a discussion on real numbers, their properties and applications, and arithmetical operations over real numbers. The reader is then introduced to the concept of function, i
Stepanov, Serguei; Sánchez, Marcos Plata; Hernández, Eliseo Hernández
2016-09-10
Experimental investigations of the main noise sources that limit the sensitivity of the adaptive interferometric all-fiber sensors operating in the communication wavelength region are reported. Adaptive properties (i.e., the autostabilization of an optimal operation point of the interferometer) are enabled by the dynamic population grating recorded in a segment of the erbium-doped fiber (EDF) at milliwatt-scale cw power in the 1480-1560 nm spectral range. The utilized symmetric Sagnac configuration with low light internal reflections ensures reduced sensitivity of the sensor to phase noise of the laser, while intensity noise is reduced to an insignificant level by the balanced detection scheme. It is shown that the fluorescence from the erbium ions, excited by the counterpropagating waves recording the grating, increases the noise level from the fundamental shot noise approximately by a factor of 2-3 only. It is also shown that conventional communication distributed feedback (DFB) semiconductor lasers with megahertz linewidth are not suitable for high-sensitivity applications of such sensors. Because of inevitable backreflections from the output terminal devices (photodiodes, insulators, circulator), the above-mentioned fundamental noise level is increased by 2 orders of magnitude due to high phase noise of the DFB laser.
The subjective importance of noise spectral content
Baxter, Donald; Phillips, Jonathan; Denman, Hugh
2014-01-01
This paper presents secondary Standard Quality Scale (SQS2) rankings in overall quality JNDs for a subjective analysis of the 3 axes of noise, amplitude, spectral content, and noise type, based on the ISO 20462 softcopy ruler protocol. For the initial pilot study, a Python noise simulation model was created to generate the matrix of noise masks for the softcopy ruler base images with different levels of noise, different low pass filter noise bandwidths and different band pass filter center frequencies, and 3 different types of noise: luma only, chroma only, and luma and chroma combined. Based on the lessons learned, the full subjective experiment, involving 27 observers from Google, NVIDIA and STMicroelectronics was modified to incorporate a wider set of base image scenes, and the removal of band pass filtered noise masks to ease observer fatigue. Good correlation was observed with the Aptina subjective noise study. The absence of tone mapping in the noise simulation model visibly reduced the contrast at high levels of noise, due to the clipping of the high levels of noise near black and white. Under the 34-inch viewing distance, no significant difference was found between the luma only noise masks and the combined luma and chroma noise masks. This was not the intuitive expectation. Two of the base images with large uniform areas, `restaurant' and `no parking', were found to be consistently more sensitive to noise than the texture rich scenes. Two key conclusions are (1) there are fundamentally different sensitivities to noise on a flat patch versus noise in real images and (2) magnification of an image accentuates visual noise in a way that is non-representative of typical noise reduction algorithms generating the same output frequency. Analysis of our experimental noise masks applied to a synthetic Macbeth ColorChecker Chart confirmed the color-dependent nature of the visibility of luma and chroma noise.
Ambiguity functions and noise floor suppression in random noise radar
Axelsson, Sune R. J.
2006-09-01
Noise radar can be used in a great number of applications including SAR. The non-periodic waveform suppresses the range ambiguity and reduces the probability of intercept and interference. Due to the randomness of the waveform, a noise floor limiting the possible side lobe suppression accompanies the correlation integral involved. In strong clutter scenes with dominant reflectors, the induced noise floor can be too high and further suppression is needed. In this paper, the ambiguity function of random noise waveforms is first analyzed, and an improved formulation is introduced to include the noise floor effect. The use of mismatched filtering for improved sidelobe suppression is then discussed. Finally, an iterative subtraction algorithm is analyzed for noise floor cancellation in the presence of dominating reflectors. This method is successfully tested on random step frequency radar data and noise sodar data.
Tackling the Limits of Optical Fiber Links
Stefani, Fabio; Bercy, Anthony; Lee, Won-Kyu; Chardonnet, Christian; Santarelli, Giorgio; Pottie, Paul-Eric; Amy-Klein, Anne
2014-01-01
We theoretically and experimentally investigate relevant noise processes arising in optical fiber links, which fundamentally limit their relative stability. We derive the unsuppressed delay noise for three configurations of optical links: two-way method, Sagnac interferometry, and actively compensated link, respectively designed for frequency comparison, rotation sensing, and frequency transfer. We also consider an alternative two-way setup allowing real-time frequency comparison and demonstrate its effectiveness on a proof-of-principle experiment with a 25-km fiber spool. For these three configurations, we analyze the noise arising from uncommon fiber paths in the interferometric ensemble and design optimized interferometers. We demonstrate interferometers with very low temperature sensitivity of respectively -2.2, -0.03 and 1 fs/K. We use one of these optimized interferometers on a long haul compensated fiber link of 540km. We obtain a relative frequency stability of 3E-20 after 10,000 s of integration time...
Babu, V
2014-01-01
Fundamentals of Gas Dynamics, Second Edition isa comprehensively updated new edition and now includes a chapter on the gas dynamics of steam. It covers the fundamental concepts and governing equations of different flows, and includes end of chapter exercises based on the practical applications. A number of useful tables on the thermodynamic properties of steam are also included.Fundamentals of Gas Dynamics, Second Edition begins with an introduction to compressible and incompressible flows before covering the fundamentals of one dimensional flows and normal shock wav
Ramachandran, V.; Halfpenny, PJ; Roberts, KJ
2017-01-01
The fundamentals of crystal science notably crystallography, crystal chemistry, crystal defects, crystal morphology and the surface chemistry of crystals are introduced with particular emphasis on organic crystals.
Noise in space. [effect on Skylab astronauts
Rader, W. P.; Baratono, J.; Bandgren, H.; Erwin, R.
1975-01-01
The Skylab program presented an excellent opportunity to investigate the effects of noise on man confined in limited space for long periods of time. This paper summarizes the results of a 4-year study to achieve a habitable noise environment for the Skylab astronauts. Noise control measures are described and noise measurements obtained during the Skylab missions are presented, as well as the astronauts' reactions to and evaluations of the noise environment.
Productive Parasites: Thinking of Noise as Affect
Directory of Open Access Journals (Sweden)
Marie Thompson
2012-11-01
Full Text Available Drawing from Michel Serres’ notion of the parasite, this article provides a nuanced explanation for noise that distinguishes itself from prevailing negative narratives, which often seek to define noise as unwanted, undesirable or damaging sound. Such narratives have left noise vulnerable to moralising polemics, which construct silence and noise as a dichotomy between the past and present, natural and cultural, relaxing and disturbing, and, fundamentally, good and bad. This article facilitates a reconsideration of noise’s ethical connotations by proposing the notion of noise as affect.
Nonlinear limits to the information capacity of optical fiber communications
Mitra, P P; Mitra, Partha P.; Stark, Jason B.
2000-01-01
The exponential growth in the rate at which information can be communicated through an optical fiber is a key element in the so called information revolution. However, like all exponential growth laws, there are physical limits to be considered. The nonlinear nature of the propagation of light in optical fiber has made these limits difficult to elucidate. Here we obtain basic insights into the limits to the information capacity of an optical fiber arising from these nonlinearities. The key simplification lies in relating the nonlinear channel to a linear channel with multiplicative noise, for which we are able to obtain analytical results. In fundamental distinction to the linear additive noise case, the capacity does not grow indefinitely with increasing signal power, but has a maximal value. The ideas presented here have broader implications for other nonlinear information channels, such as those involved in sensory transduction in neurobiology. These have been often examined using additive noise linear cha...
Halliday, David; Resnick, Robert; Walker, Jearl
2003-01-01
No other book on the market today can match the success of Halliday, Resnick and Walker's Fundamentals of Physics! In a breezy, easy-to-understand style the book offers a solid understanding of fundamental physics concepts, and helps readers apply this conceptual understanding to quantitative problem solving.
Directory of Open Access Journals (Sweden)
Justin Zylstra
2014-12-01
Full Text Available I argue that dependence is neither necessary nor sufficient for relative fundamentality. I then introduce the notion of 'likeness in nature' and provide an account of relative fundamentality in terms of it and the notion of dependence. Finally, I discuss some puzzles that arise in Aristotle's Categories, to which the theory developed is applied.
... Search Clean Air Act Overview Share Facebook Twitter Google+ Pinterest Contact Us Clean Air Act Title IV - ... noises in the community (from your neighbor, boom cars, lawn equipment, etc.) and from commercial businesses (factory, ...
Noise Effects in the Mode-Locked External Cavity Lasers
Institute of Scientific and Technical Information of China (English)
Nuran Dogru; M. Sadettin Ozyazici
2003-01-01
Effect of high level of spontaneous and carrier noise on mode-locked hybrid soliton pulse source and relative intensity noise is described. Transform limited pulses are not generated over a wide frequency range because of these noises.
Schubert, Thomas F
2015-01-01
This book, Electronic Devices and Circuit Application, is the first of four books of a larger work, Fundamentals of Electronics. It is comprised of four chapters describing the basic operation of each of the four fundamental building blocks of modern electronics: operational amplifiers, semiconductor diodes, bipolar junction transistors, and field effect transistors. Attention is focused on the reader obtaining a clear understanding of each of the devices when it is operated in equilibrium. Ideas fundamental to the study of electronic circuits are also developed in the book at a basic level to
Different Variants of Fundamental Portfolio
Directory of Open Access Journals (Sweden)
Tarczyński Waldemar
2014-06-01
Full Text Available The paper proposes the fundamental portfolio of securities. This portfolio is an alternative for the classic Markowitz model, which combines fundamental analysis with portfolio analysis. The method’s main idea is based on the use of the TMAI1 synthetic measure and, in limiting conditions, the use of risk and the portfolio’s rate of return in the objective function. Different variants of fundamental portfolio have been considered under an empirical study. The effectiveness of the proposed solutions has been related to the classic portfolio constructed with the help of the Markowitz model and the WIG20 market index’s rate of return. All portfolios were constructed with data on rates of return for 2005. Their effectiveness in 2006- 2013 was then evaluated. The studied period comprises the end of the bull market, the 2007-2009 crisis, the 2010 bull market and the 2011 crisis. This allows for the evaluation of the solutions’ flexibility in various extreme situations. For the construction of the fundamental portfolio’s objective function and the TMAI, the study made use of financial and economic data on selected indicators retrieved from Notoria Serwis for 2005.
Noise floor reduction of an Er:fiber laser-based photonic microwave generator
Jiang, Haifeng; Quinlan, Franklyn; Fortier, Tara; Diddams, Scott A
2011-01-01
The generation of microwaves from optical signals suffers from thermal and shot noise inherent in the photodetection process. This problem is more acute at lower pulse repetition rates where photodiode saturation limits the achievable signal-to-noise ratio. In this paper, we demonstrate a 10-15 dB reduction in the 10 GHz phase noise floor by multiplication of the pulse repetition rate. Starting with a 250 MHz fundamentally mode-locked erbium(Er):fiber laser, we compare two different approaches to repetition rate multiplication: Fabry-Perot cavity filtering and a cascaded, unbalanced Mach-Zehnder fiber-based interferometer. These techniques reduce the phase noise floor on the 10 GHz photodetected harmonic to -158 dBc/Hz and -162 dBc/Hz, respectively, for Fourier frequencies higher than 100 kHz.
Noise Suppression of a single Frequency Fiber Laser
Institute of Scientific and Technical Information of China (English)
LIU Kui; CUI Shu-Zhen; ZHANG Hai-Long; ZHANG Jun-Xiang; GAO Jiang-Rui
2011-01-01
We present an experimental demonstration of fiber laser noise suppression by the mode cleaner.The intensity noise of a single frequency fiber laser is suppressed near the shot noise limit after a sideband frequency of 3 MHz.Two series mode cleaners are used to improve the noise suppression.The noise reduction is over 27 dB at 3 MHz.
Health Effects of Noise Exposure in Children.
Stansfeld, Stephen; Clark, Charlotte
2015-06-01
Environmental noise exposure, such as road traffic noise and aircraft noise, is associated with a range of health outcomes in children. Children demonstrate annoyance responses to noise, and noise is also related to lower well-being and stress responses, such as increased levels of adrenaline and noradrenaline. Noise does not cause more serious mental health problems, but there is growing evidence for an association with increased hyperactivity symptoms. Studies also suggest that noise might cause changes in cardiovascular functioning, and there is some limited evidence for an effect on low birth weight. There is robust evidence for an effect of school noise exposure on children's cognitive skills such as reading and memory, as well as on standardised academic test scores. Environmental noise does not usually reach levels that are likely to affect children's hearing; however, increasing use of personal electronic devices may leave some children exposed to harmful levels of noise.
Fundamentals of electrochemical science
Oldham, Keith
1993-01-01
Key Features* Deals comprehensively with the basic science of electrochemistry* Treats electrochemistry as a discipline in its own right and not as a branch of physical or analytical chemistry* Provides a thorough and quantitative description of electrochemical fundamentals
Fundamentals of crystallography
2011-01-01
Crystallography is a basic tool for scientists in many diverse disciplines. This text offers a clear description of fundamentals and of modern applications. It supports curricula in crystallography at undergraduate level.
Fundamentals of structural dynamics
Craig, Roy R
2006-01-01
From theory and fundamentals to the latest advances in computational and experimental modal analysis, this is the definitive, updated reference on structural dynamics.This edition updates Professor Craig's classic introduction to structural dynamics, which has been an invaluable resource for practicing engineers and a textbook for undergraduate and graduate courses in vibrations and/or structural dynamics. Along with comprehensive coverage of structural dynamics fundamentals, finite-element-based computational methods, and dynamic testing methods, this Second Edition includes new and e
Masses of Fundamental Particles
Terazawa, Hidezumi
2011-01-01
Not only the masses of fundamental particles including the weak bosons, Higgs scalar, quarks, and leptons, but also the mixing angles of quarks and those of neutrinos are all explained and/or predicted in the unified composite model of quarks and leptons successfully. In addition, both of the two anomalies recently found by the CDF Collaboration are suggested to be taken as evidences for the substructure of the fundamental particles.
Information security fundamentals
Peltier, Thomas R
2013-01-01
Developing an information security program that adheres to the principle of security as a business enabler must be the first step in an enterprise's effort to build an effective security program. Following in the footsteps of its bestselling predecessor, Information Security Fundamentals, Second Edition provides information security professionals with a clear understanding of the fundamentals of security required to address the range of issues they will experience in the field.The book examines the elements of computer security, employee roles and r
Noise-powered probabilistic concentration of phase information
DEFF Research Database (Denmark)
Castaneda, Mario A. Usuga; Muller, C. R.; Wittmann, C.
2010-01-01
Phase-insensitive optical amplification of an unknown quantum state is known to be a fundamentally noisy operation that inevitably adds noise to the amplified state(1-5). However, this fundamental noise penalty in amplification can be circumvented by resorting to a probabilistic scheme as recentl...
Occupational noise in printing companies.
Mihailovic, Aleksandra; Grujic, Selena D; Kiurski, Jelena; Krstic, Jelena; Oros, Ivana; Kovacevic, Ilija
2011-10-01
The extent of noise in five printing companies in Novi Sad, Serbia, was determined using TES-1358A Sound Analyzer with RS-232 Interface. The data on equivalent A-level (dBA), as well as, maximum and minimum sound pressure levels were collected. It was found that folders and offset printing units are the predominant noise sources, with the average L (eq) levels of 87.66 and 82.7 dBA, respectively. Forty percent of the machines produced noise levels above the limiting threshold level of 85 dBA, allowed by law. The noise in all printing companies was dominated by higher frequency noise, and the maximum level mostly appeared at 4,000 Hz. For offset printing machines and folders, the means of L (eq) levels exceeded the permissible levels given by NR-80 curve at higher frequencies. There are no published studies of occupational noise and hearing impairment of workers exposed to hazardous noise in printing industry in Serbia. More extensive studies are needed to determine the exact impact of noise on the workers. Technical and organizational measures in order to control noise and prevent noise exposure, and general hearing conservation program to protect workers, should be introduced in printing industry.
Genoni, Marco G.; Duarte, O. S.; Serafini, Alessio
2016-10-01
Inspired by the notion that environmental noise is in principle observable, while fundamental noise due to spontaneous localization would not be, we study the estimation of the diffusion parameter induced by wave function collapse models under continuous monitoring of the environment. We take into account finite measurement efficiencies and, in order to quantify the advantage granted by monitoring, we analyse the quantum Fisher information associated with such a diffusion parameter, identify optimal measurements in limiting cases, and assess the performance of such measurements in more realistic conditions.
The Development of a Practical, Drift-Free, Johnson-Noise Thermometer for Industrial Applications
Bramley, Paul; Cruickshank, David; Pearce, Jonathan
2017-02-01
Johnson noise thermometers measure a phenomenon that is directly linked to thermodynamic temperature by a fundamental physical law. The measurement of Johnson noise therefore offers the prospect of realizing a drift-free thermometer. Despite previous attempts to produce a practical Johnson noise thermometer for industrial applications, the technique is currently used only in niche research applications to explore discrepancies between practical temperature scales and thermodynamic temperature, or to determine Boltzmann's constant. This has largely been due to the historical use of switched correlators to measure Johnson noise, which limits the sense resistance and measurement bandwidth that can be employed. This constraint limits the Johnson noise signal to levels near the limits of measurement. A new technique that eliminates switching and thereby allows the use of much higher sense resistances and bandwidths to increase the Johnson noise signal is presented. The signal power achieved is significantly higher than for systems using a switched correlator. Results so far indicate that measurement performance is compatible with the requirements of industrial applications. Specifically, uncertainties of <0.3°C (95 % confidence) were demonstrated for measurements near ambient temperature with a measurement time of only 7 s.
Variation of fundamental constants: theory
Flambaum, Victor
2008-05-01
Theories unifying gravity with other interactions suggest temporal and spatial variation of the fundamental ``constants'' in expanding Universe. There are some hints for the variation of different fundamental constants in quasar absorption spectra and Big Bang nucleosynthesis data. A large number of publications (including atomic clocks) report limits on the variations. We want to study the variation of the main dimensionless parameters of the Standard Model: 1. Fine structure constant alpha (combination of speed of light, electron charge and Plank constant). 2. Ratio of the strong interaction scale (LambdaQCD) to a fundamental mass like electron mass or quark mass which are proportional to Higgs vacuum expectation value. The proton mass is propotional to LambdaQCD, therefore, the proton-to-electron mass ratio comes into this second category. We performed necessary atomic, nuclear and QCD calculations needed to study variation of the fundamental constants using the Big Bang Nucleosynthsis, quasar spectra, Oklo natural nuclear reactor and atomic clock data. The relative effects of the variation may be enhanced in transitions between narrow close levels in atoms, molecules and nuclei. If one will study an enhanced effect, the relative value of systematic effects (which are not enhanced) may be much smaller. Note also that the absolute magnitude of the variation effects in nuclei (e.g. in very narrow 7 eV transition in 229Th) may be 5 orders of magnitude larger than in atoms. A different possibility of enhancement comes from the inversion transitions in molecules where splitting between the levels is due to the quantum tunneling amplitude which has strong, exponential dependence on the electron to proton mass ratio. Our study of NH3 quasar spectra has already given the best limit on the variation of electron to proton mass ratio.
First Steps for a Giant FOG: Searching for the Limits
Guattari, Frederic; Lucas, Alexandra; Foughali, Ghaieth; Bigueur, Alexandre; de Toldi, Elliot; Schreiber, Ulrich; Wassermann, Joachim
2017-04-01
Based on recent experiences in constructing very low noise fibre-optic gyroscopes (FOG) dedicated to seismology, we will present first performance results of a large fibre-optic coil (approx. 1m diameter). Next to in house (iXBlue) factory testing the self-noise of the new sensor is estimated by co-locating it to existing high performance large ring lasers located in Wettzell and Fürstenfeldbruck (Germany), respectively. The reason for constructing this huge FOG is to evaluate experimentally the physical limits (if any exists) of this kind of technology. While this experiment is probing the fundamental limits of FOGs technology and thus is interesting from the construction point of view, it also serves as a first step for cost effective very low noise laboratory rotational seismometer and leads in a second step to performance improvements on portable rotational seismometer
Image reconstruction under non-Gaussian noise
DEFF Research Database (Denmark)
Sciacchitano, Federica
During acquisition and transmission, images are often blurred and corrupted by noise. One of the fundamental tasks of image processing is to reconstruct the clean image from a degraded version. The process of recovering the original image from the data is an example of inverse problem. Due......D thesis intends to solve some of the many open questions for image restoration under non-Gaussian noise. The two main kinds of noise studied in this PhD project are the impulse noise and the Cauchy noise. Impulse noise is due to for instance the malfunctioning pixel elements in the camera sensors, errors...... that the CM estimate outperforms the MAP estimate, when the error depends on Bregman distances. This PhD project can have many applications in the modern society, in fact the reconstruction of high quality images with less noise and more details enhances the image processing operations, such as edge detection...
Sub-Shot Noise Power Source for Microelectronics
Strekalov, Dmitry V.; Yu, Nan; Mansour, Kamjou
2011-01-01
Low-current, high-impedance microelectronic devices can be affected by electric current shot noise more than they are affected by Nyquist noise, even at room temperature. An approach to implementing a sub-shot noise current source for powering such devices is based on direct conversion of amplitude-squeezed light to photocurrent. The phenomenon of optical squeezing allows for the optical measurements below the fundamental shot noise limit, which would be impossible in the domain of classical optics. This becomes possible by affecting the statistical properties of photons in an optical mode, which can be considered as a case of information encoding. Once encoded, the information describing the photon (or any other elementary excitations) statistics can be also transmitted. In fact, it is such information transduction from optics to an electronics circuit, via photoelectric effect, that has allowed the observation of the optical squeezing. It is very difficult, if not technically impossible, to directly measure the statistical distribution of optical photons except at extremely low light level. The photoelectric current, on the other hand, can be easily analyzed using RF spectrum analyzers. Once it was observed that the photocurrent noise generated by a tested light source in question is below the shot noise limit (e.g. produced by a coherent light beam), it was concluded that the light source in question possess the property of amplitude squeezing. The main novelty of this technology is to turn this well-known information transduction approach around. Instead of studying the statistical property of an optical mode by measuring the photoelectron statistics, an amplitude-squeezed light source and a high-efficiency linear photodiode are used to generate photocurrent with sub-Poissonian electron statistics. By powering microelectronic devices with this current source, their performance can be improved, especially their noise parameters. Therefore, a room-temperature sub
Lazaro; Herod; Domin; Zhuo; Islas; Kandiyoti
1999-01-01
Three methods for determining a 'safe' estimate for high-mass limits of MALDI spectra of coal derived liquids were explored, using a sample of coal-tar pitch and its pyridine-insoluble fraction. Co-addition of increasing numbers of single-shot spectra (10, 30, 50 and 100 pulses) showed visually observable reductions in noise levels, consistent with robust and statistically meaningful signals. Three separate types of post-acquisition calculation were used to identify high-mass limits of the spectra. (i) A literature method indicated high-mass limits similar to those observed visually-as a shift from baseline at the highest masses, nearly 350 000 u for the coal tar pitch and about 390 000 u for its pyridine insoluble fraction. (ii) Comparing instrument signal with pre-selected multiples of the standard deviation, upper mass estimates of between 40-60 000 u for the coal-tar pitch and about 95 000 u for its pyridine-insoluble fraction were found. (iii) Calculation of the slope was used to identify 'lift-off' of the spectrum from baseline. The angle between the smoothed spectrum and the baseline was matched to a pre-selected value (e.g. 0.5 degrees and 1 degrees ). However, the arbitrary specification of the key parameter did not establish this last method on a firm basis. The choice of a criterion for estimating high-mass limits of MALDI spectra remains a semi-quantitative procedure; a reasonably conservative high-mass limit may be estimated by comparison of signal with five times the standard deviation. However, evaluation of size exclusion chromatograms of the present samples using polystyrene standards suggests that molecular mass distributions of pitch samples arrived at by MALDI mass spectrometry are, at least partly, determined by the limitations of available instruments. Copyright 1999 John Wiley & Sons, Ltd.
Towards a general framework for including noise impacts in LCA.
Cucurachi, Stefano; Heijungs, Reinout; Ohlau, Katrin
Several damages have been associated with the exposure of human beings to noise. These include auditory effects, i.e., hearing impairment, but also non-auditory physiological ones such as hypertension and ischemic heart disease, or psychological ones such as annoyance, depression, sleep disturbance, limited performance of cognitive tasks or inadequate cognitive development. Noise can also interfere with intended activities, both in daytime and nighttime. ISO 14'040 also indicated the necessity of introducing noise, together with other less developed impact categories, in a complete LCA study, possibly changing the results of many LCA studies already available. The attempts available in the literature focused on the integration of transportation noise in LCA. Although being considered the most frequent source of intrusive impact, transportation noise is not the only type of noise that can have a malign impact on public health. Several other sources of noise such as industrial or occupational need to be taken into account to have a complete consideration of noise into LCA. Major life cycle inventories (LCI) typically do not contain data on noise emissions yet and characterisation factors are not yet clearly defined. The aim of the present paper is to briefly review what is already available in the field and propose a new framework for the consideration of human health impacts of any type of noise that could be of interest in the LCA practice, providing indications for the introduction of noise in LCI and analysing what data is already available and, in the form of a research agenda, what other resources would be needed to reach a complete coverage of the problem. The literature production related to the impacts of noise on human health has been analysed, with considerations of impacts caused by transportation noise as well as occupational and industrial noise. The analysis of the specialist medical literature allowed for a better understanding of how to deal with the
Variation of Fundamental Constants
Flambaum, V. V.
2006-11-01
Theories unifying gravity with other interactions suggest temporal and spatial variation of the fundamental ``constants'' in expanding Universe. The spatial variation can explain a fine tuning of the fundamental constants which allows humans (and any life) to appear. We appeared in the area of the Universe where the values of the fundamental constants are consistent with our existence. We present a review of recent works devoted to the variation of the fine structure constant α, strong interaction and fundamental masses. There are some hints for the variation in quasar absorption spectra. Big Bang nucleosynthesis, and Oklo natural nuclear reactor data. A very promising method to search for the variation of the fundamental constants consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transition between accidentally degenerate atomic and molecular energy levels. A new idea is to build a ``nuclear'' clock based on the ultraviolet transition between very low excited state and ground state in Thorium nucleus. This may allow to improve sensitivity to the variation up to 10 orders of magnitude! Huge enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feshbach resonance.
Prewhitening for Rank-Deficient Noise in Subspace Methods for Noise Reduction
DEFF Research Database (Denmark)
Hansen, Per Christian; Jensen, Søren Holdt
2005-01-01
A fundamental issue in connection with subspace methods for noise reduction is that the covariance matrix for the noise is required to have full rank, in order for the prewhitening step to be defined. However, there are important cases where this requirement is not fulfilled, e.g., when the noise...... also for rank deficient noise. We also demonstrate how to formulate this algorithm by means of a quotient ULV decomposition, which allows for faster computation and updating. Finally we apply our algorithm to a problem involving a speech signal contaminated by narrow-band noise....
Space noise synthetic aperture radar
Kulpa, Krzysztof S.
2006-03-01
The paper presents limitations of space borne synthetic aperture radars, caused by range and Doppler velocity ambiguities, and the concept of usage of the noise radar technology for creation of high-resolution space SAR images. The noise SAR is free from limitation caused by the periodicity of pulse waveform ambiguity function, and therefore this technology can be used in the future space missions. The basic concept of noise SAR image formation is also presented. The image formation algorithm has been verified using the simulated data produced by Raw Radar Data Simulator.
Thermal noise of a gram-scale cantilever flexure
Nguyen, Thanh T-H; Miller, John; Mow-Lowry, Conor M; Goßler, Stefan; Shaddock, Daniel A; McClelland, David E
2015-01-01
Measured thermal noise displacement spectra from low frequency to $3\\,$kHz of Niobium and Aluminium flexures are presented. With a simple thermal noise model dominated by structural and thermoelastic losses, the agreement between the theory and measurement has been robust. The thermal noise spectra were recorded up to an order of magnitude below and above the fundamental resonance, with the fundamental resonances for both Aluminium and Niobium flexures within the range of $50\\,$Hz to $300\\,$Hz
Fundamentals of algebraic topology
Weintraub, Steven H
2014-01-01
This rapid and concise presentation of the essential ideas and results of algebraic topology follows the axiomatic foundations pioneered by Eilenberg and Steenrod. The approach of the book is pragmatic: while most proofs are given, those that are particularly long or technical are omitted, and results are stated in a form that emphasizes practical use over maximal generality. Moreover, to better reveal the logical structure of the subject, the separate roles of algebra and topology are illuminated. Assuming a background in point-set topology, Fundamentals of Algebraic Topology covers the canon of a first-year graduate course in algebraic topology: the fundamental group and covering spaces, homology and cohomology, CW complexes and manifolds, and a short introduction to homotopy theory. Readers wishing to deepen their knowledge of algebraic topology beyond the fundamentals are guided by a short but carefully annotated bibliography.
Dick, Erik
2015-01-01
This book explores the working principles of all kinds of turbomachines. The same theoretical framework is used to analyse the different machine types. Fundamentals are first presented and theoretical concepts are then elaborated for particular machine types, starting with the simplest ones.For each machine type, the author strikes a balance between building basic understanding and exploring knowledge of practical aspects. Readers are invited through challenging exercises to consider how the theory applies to particular cases and how it can be generalised. The book is primarily meant as a course book. It teaches fundamentals and explores applications. It will appeal to senior undergraduate and graduate students in mechanical engineering and to professional engineers seeking to understand the operation of turbomachines. Readers will gain a fundamental understanding of turbomachines. They will also be able to make a reasoned choice of turbomachine for a particular application and to understand its operation...
Energy Technology Data Exchange (ETDEWEB)
Brown, F.B.; Sutton, T.M.
1996-02-01
This report is composed of the lecture notes from the first half of a 32-hour graduate-level course on Monte Carlo methods offered at KAPL. These notes, prepared by two of the principle developers of KAPL`s RACER Monte Carlo code, cover the fundamental theory, concepts, and practices for Monte Carlo analysis. In particular, a thorough grounding in the basic fundamentals of Monte Carlo methods is presented, including random number generation, random sampling, the Monte Carlo approach to solving transport problems, computational geometry, collision physics, tallies, and eigenvalue calculations. Furthermore, modern computational algorithms for vector and parallel approaches to Monte Carlo calculations are covered in detail, including fundamental parallel and vector concepts, the event-based algorithm, master/slave schemes, parallel scaling laws, and portability issues.
Policy and the evaluation of aircraft noise
Kroesen, M.; Molin, E.J.E.; Van Wee, G.P.
2010-01-01
In this paper, we hypothesize and test the ideas that (1) people’s subjectivity in relation to aircraft noise is shaped by the policy discourse, (2) this results in a limited number of frames towards aircraft noise, (3) the frames inform people how to think and feel about aircraft noise and (4) the
Expectations of two-level telegraph noise
Fern, J
2006-01-01
We find expectation values of functions of time integrated two-level telegraph noise. Expectation values of this noise are evaluated under simple control pulses. Both the Gaussian limit and $1/f$ noise are considered. We apply the results to a specific superconducting quantum computing example, which illustrates the use of this technique for calculating error probabilities.
Policy and the evaluation of aircraft noise
Kroesen, M.; Molin, E.J.E.; Van Wee, G.P.
2010-01-01
In this paper, we hypothesize and test the ideas that (1) people’s subjectivity in relation to aircraft noise is shaped by the policy discourse, (2) this results in a limited number of frames towards aircraft noise, (3) the frames inform people how to think and feel about aircraft noise and (4) the
Institute of Scientific and Technical Information of China (English)
张维森; 杜伟佳; 王致; 麦诗琪; 许启荣; 刘移民
2011-01-01
目的 调查广州工厂作业岗位工业噪声超标现状,为开展噪声职业病危害防治工作提供参考.方法 现场监测、现况调查广州工厂211家,按企业性质、规模大小、所处区域、所属行业和监测时间等分布进行分析与评价.结果 被调查工厂以国企和合资企业为主,多数为中型企业,分布在城区,主要涉及机动车与船舶制造业、电子与电气设备制造业和石油化工行业.合资和民营企业噪声超标较明显,超标率分别为36.0%和31.2%,主要表现在纺织、食品与饮料制造和皮革制品等行业,超标率分别为46.7%、43.1%和41.3%,电子与电气设备制造、机动车与船舶制造和印刷与文体制品业等行业噪声超标现象也较明显,超标率均超过35%;南沙工业区和番禺区企业、大型企业噪声超标率也都超过35%;春、夏季节监测的企业噪声超标率较高;调整各相关因素后的多因素回归分析结果也与此一致.最常见的超标点主要集中在与机械加工制造相关行业的剪切锯、铣抛磨、压铆钻、焊接、装配和质检工种,与制药、食品饮料制造业相关的质检和包装,纺织业的纺纱和打线,辅助工作的清洗和维修以及空压机、冷机、风机、发电机、泵房等辅助用房的巡查维护等岗位.结论 广州工厂工业噪声行业和区域分布广,加强重点区域、重点行业、重点岗位工业噪声职业病危害防治应是今后的工作重点.%Objective To investigate the industrial noise over-limit status of the worksites in Guangzhou factories, so as to promote the prevention and control of occupational noise hazards. Methods 211 factories in Guangzhou were monitored and investigated. The analysis and assessment were developed for the properties and size of the factories, the districts of the factories being located, the industries of the factories being classified and the date of monitoring. Results In this understudied
Fundamentals of fluid lubrication
Hamrock, Bernard J.
1991-01-01
The aim is to coordinate the topics of design, engineering dynamics, and fluid dynamics in order to aid researchers in the area of fluid film lubrication. The lubrication principles that are covered can serve as a basis for the engineering design of machine elements. The fundamentals of fluid film lubrication are presented clearly so that students that use the book will have confidence in their ability to apply these principles to a wide range of lubrication situations. Some guidance on applying these fundamentals to the solution of engineering problems is also provided.
Infosec management fundamentals
Dalziel, Henry
2015-01-01
Infosec Management Fundamentals is a concise overview of the Information Security management concepts and techniques, providing a foundational template for both experienced professionals and those new to the industry. This brief volume will also appeal to business executives and managers outside of infosec who want to understand the fundamental concepts of Information Security and how it impacts their business decisions and daily activities. Teaches ISO/IEC 27000 best practices on information security management Discusses risks and controls within the context of an overall information securi
Smith, Peter
2013-01-01
Written for the piping engineer and designer in the field, this two-part series helps to fill a void in piping literature,since the Rip Weaver books of the '90s were taken out of print at the advent of the Computer Aid Design(CAD) era. Technology may have changed, however the fundamentals of piping rules still apply in the digitalrepresentation of process piping systems. The Fundamentals of Piping Design is an introduction to the designof piping systems, various processes and the layout of pipe work connecting the major items of equipment forthe new hire, the engineering student and the vetera
Homeschooling and religious fundamentalism
Directory of Open Access Journals (Sweden)
Robert KUNZMAN
2010-10-01
Full Text Available This article considers the relationship between homeschooling and religious fundamentalism by focusing on their intersection in the philosophies and practices of conservative Christian homeschoolers in the United States. Homeschooling provides an ideal educational setting to support several core fundamentalist principles: resistance to contemporary culture; suspicion of institutional authority and professional expertise; parental control and centrality of the family; and interweaving of faith and academics. It is important to recognize, however, that fundamentalism exists on a continuum; conservative religious homeschoolers resist liberal democratic values to varying degrees, and efforts to foster dialogue and accommodation with religious homeschoolers can ultimately helpstrengthen the broader civic fabric.
Pragmatic electrical engineering fundamentals
Eccles, William
2011-01-01
Pragmatic Electrical Engineering: Fundamentals introduces the fundamentals of the energy-delivery part of electrical systems. It begins with a study of basic electrical circuits and then focuses on electrical power. Three-phase power systems, transformers, induction motors, and magnetics are the major topics.All of the material in the text is illustrated with completely-worked examples to guide the student to a better understanding of the topics. This short lecture book will be of use at any level of engineering, not just electrical. Its goal is to provide the practicing engineer with a practi
Fundamentals of nonlinear optics
Powers, Peter E
2011-01-01
Peter Powers's rigorous but simple description of a difficult field keeps the reader's attention throughout. … All chapters contain a list of references and large numbers of practice examples to be worked through. … By carefully working through the proposed problems, students will develop a sound understanding of the fundamental principles and applications. … the book serves perfectly for an introductory-level course for second- and third-order nonlinear optical phenomena. The author's writing style is refreshing and original. I expect that Fundamentals of Nonlinear Optics will fast become pop
Fundamentals of continuum mechanics
Rudnicki, John W
2014-01-01
A concise introductory course text on continuum mechanics Fundamentals of Continuum Mechanics focuses on the fundamentals of the subject and provides the background for formulation of numerical methods for large deformations and a wide range of material behaviours. It aims to provide the foundations for further study, not just of these subjects, but also the formulations for much more complex material behaviour and their implementation computationally. This book is divided into 5 parts, covering mathematical preliminaries, stress, motion and deformation, balance of mass, momentum and energ
Antennas fundamentals, design, measurement
Long, Maurice
2009-01-01
This comprehensive revision (3rd Edition) is a senior undergraduate or first-year graduate level textbook on antenna fundamentals, design, performance analysis, and measurements. In addition to its use as a formal course textbook, the book's pragmatic style and emphasis on the fundamentals make it especially useful to engineering professionals who need to grasp the essence of the subject quickly but without being mired in unnecessary detail. This new edition was prepared for a first year graduate course at Southern Polytechnic State University in Georgia. It provides broad coverage of antenna
Reis, Mario
2013-01-01
The Fundamentals of Magnetism is a truly unique reference text, that explores the study of magnetism and magnetic behavior with a depth that no other book can provide. It covers the most detailed descriptions of the fundamentals of magnetism providing an emphasis on statistical mechanics which is absolutely critical for understanding magnetic behavior. The books covers the classical areas of basic magnetism, including Landau Theory and magnetic interactions, but features a more concise and easy-to-read style. Perfect for upper-level graduate students and industry researchers, The Fu
Better Faster Noise with the GPU
DEFF Research Database (Denmark)
Wyvill, Geoff; Frisvad, Jeppe Revall
Filtered noise [Perlin 1985] has, for twenty years, been a fundamental tool for creating functional texture and it has many other applications; for example, animating water waves or the motion of grass waving in the wind. Perlin noise suffers from a number of defects and there have been many atte...... attempts to create better or faster noise but Perlin’s ‘Gradient Noise’ has consistently proved to be the best compromise between speed and quality. Our objective was to create a better noise cheaply by use of the GPU....
Evanescent single-molecule biosensing with quantum limited precision
Mauranyapin, N P; Taylor, M A; Waleed, M; Bowen, W P
2016-01-01
Sensors that are able to detect and track single unlabelled biomolecules are an important tool both to understand biomolecular dynamics and interactions at nanoscale, and for medical diagnostics operating at their ultimate detection limits. Recently, exceptional sensitivity has been achieved using the strongly enhanced evanescent fields provided by optical microcavities and nano-sized plasmonic resonators. However, at high field intensities photodamage to the biological specimen becomes increasingly problematic. Here, we introduce an optical nanofibre based evanescent biosensor that operates at the fundamental precision limit introduced by quantisation of light. This allows a four order-of-magnitude reduction in optical intensity whilst maintaining state-of-the-art sensitivity. It enable quantum noise limited tracking of single biomolecules as small as 3.5 nm, and surface-molecule interactions to be monitored over extended periods. By achieving quantum noise limited precision, our approach provides a pathway ...
Whalen, Anthony D; Declaris, Nicholas
1971-01-01
Detection of Signals in Noise serves as an introduction to the principles and applications of the statistical theory of signal detection. The book discusses probability and random processes; narrowband signals, their complex representation, and their properties described with the aid of the Hilbert transform; and Gaussian-derived processes. The text also describes the application of hypothesis testing for the detection of signals and the fundamentals required for statistical detection of signals in noise. Problem exercises, references, and a supplementary bibliography are included after each c
Homeschooling and Religious Fundamentalism
Kunzman, Robert
2010-01-01
This article considers the relationship between homeschooling and religious fundamentalism by focusing on their intersection in the philosophies and practices of conservative Christian homeschoolers in the United States. Homeschooling provides an ideal educational setting to support several core fundamentalist principles: resistance to…
Fundamental partial compositeness
DEFF Research Database (Denmark)
Sannino, Francesco; Strumia, Alessandro; Tesi, Andrea
2016-01-01
We construct renormalizable Standard Model extensions, valid up to the Planck scale, that give a composite Higgs from a new fundamental strong force acting on fermions and scalars. Yukawa interactions of these particles with Standard Model fermions realize the partial compositeness scenario. Unde...
Fundamentals of Business Economics
2013-01-01
Powerpoint presentations of the 9 theoretical units of the subject: Fundamentals of Business Economics. Business Administration Degree. Faculty of Economics. University of Alicante En el marco de ayudas a preparación de materiales docentes en lengua inglesa, por parte del Servei de Política Llingüística de la Universidad de Alicante
Fundamental Physics Microgravity Sensitivity
Israelsson, Ulf
1998-01-01
An introduction followed by a brief discussion about the sensitivity to microgravity environment disturbances for some recent and planned experiments in microgravity fundamental physics will be presented. In particular, correlation between gravity disturbances and the quality of science data sets measured by the Confined Helium Experiment (CHEX) during ground testing and during the November 1997 USMP-4 flight will be described.
Fundamental Metallurgy of Solidification
DEFF Research Database (Denmark)
Tiedje, Niels
2004-01-01
The text takes the reader through some fundamental aspects of solidification, with focus on understanding the basic physics that govern solidification in casting and welding. It is described how the first solid is formed and which factors affect nucleation. It is described how crystals grow from ...
Fundamentals of convolutional coding
Johannesson, Rolf
2015-01-01
Fundamentals of Convolutional Coding, Second Edition, regarded as a bible of convolutional coding brings you a clear and comprehensive discussion of the basic principles of this field * Two new chapters on low-density parity-check (LDPC) convolutional codes and iterative coding * Viterbi, BCJR, BEAST, list, and sequential decoding of convolutional codes * Distance properties of convolutional codes * Includes a downloadable solutions manual
This study guide provides comments and references for professional soil scientists who are studying for the soil science fundamentals exam needed as the first step for certification. The performance objectives were determined by the Soil Science Society of America's Council of Soil Science Examiners...
Fundamentals and Optimal Institutions
DEFF Research Database (Denmark)
Gonzalez-Eiras, Martin; Harmon, Nikolaj Arpe; Rossi, Martín
2016-01-01
of regulatory institutions such as revenue sharing, salary caps or luxury taxes. We show, theoretically and empirically, that these large differences in adopted institutions can be rationalized as optimal responses to differences in the fundamental characteristics of the sports being played. This provides...
Wakker, K.F.
2015-01-01
This book deals with the motion of the center of mass of a spacecraft; this discipline is generally called astrodynamics. The book focuses on an analytical treatment of the motion of spacecraft and provides insight into the fundamentals of spacecraft orbit dynamics. A large number of topics are trea
Fundamentals of plasma physics
Bittencourt, J A
1986-01-01
A general introduction designed to present a comprehensive, logical and unified treatment of the fundamentals of plasma physics based on statistical kinetic theory. Its clarity and completeness make it suitable for self-learning and self-paced courses. Problems are included.
A Maneuvering Flight Noise Model for Helicopter Mission Planning
Greenwood, Eric; Rau, Robert; May, Benjamin; Hobbs, Christopher
2015-01-01
A new model for estimating the noise radiation during maneuvering flight is developed in this paper. The model applies the Quasi-Static Acoustic Mapping (Q-SAM) method to a database of acoustic spheres generated using the Fundamental Rotorcraft Acoustics Modeling from Experiments (FRAME) technique. A method is developed to generate a realistic flight trajectory from a limited set of waypoints and is used to calculate the quasi-static operating condition and corresponding acoustic sphere for the vehicle throughout the maneuver. By using a previously computed database of acoustic spheres, the acoustic impact of proposed helicopter operations can be rapidly predicted for use in mission-planning. The resulting FRAME-QS model is applied to near-horizon noise measurements collected for the Bell 430 helicopter undergoing transient pitch up and roll maneuvers, with good agreement between the measured data and the FRAME-QS model.
Boumans, P. W. J. M.; Vrakking, J. J. A. M.
This paper links up with a previous publication by the same authors [ Spectrochim. Acta41B, 1235 (1986)] dealing with the measurement of the effective line profiles of about 350 prominent lines at high spectral resolution and the determination of the physical widths of these lines. In the present work the line widths are used for a breakdown of the detection limits obtained with these lines using different ICPs and different spectrometers. This breakdown takes into account the separate effects of source characteristics, noise, and spectral bandwidth. The availability of the numerical values of the physical widths of a large number of lines permitted a more rigorous approach than in a previous work [ Spectrochim. Acta40B, 1437 (1985)]. The present approach was applied to detection limits obtained in this work with a 50 MHz ICP at high spectral resolution and to results reported by W INGEet al. [ Appl. Spectrosc.33, 206 (1979)] and WOHLERS [ ICP Information Newslett.10, 601 (1985)]for 27 MHz ICPs. The 50 MHz ICP was shown to have an advantage in source signal-to-background ratio (SBR) with respect to either of the two 27 MHz ICPs. This SBR advantage was a factor of 3-15 with respect to the "Winge ICP" and a factor of 2-6 with respect to the "Wohlers ICP". The approach was also used to convert detection limits measured in the 50 MHz ICP at high resolution into values for 15 pm spectral bandwidth and a relative standard deviation of the background signal equal to 1%. These values are recommended as standards of performance for the conventional argon ICP. The paper comprises a tabulation of the complete results for the 350 prominent lines and includes four sets of detection limits for these lines.
Ishimoto, Yuichi; Ishizuka, Kentaro; Aikawa, Kiyoaki; Akagi, Masato
2004-01-01
This paper proposes a robust method for estimating the fundamental frequency (F0) in real environments. It is assumed that the spectral structure of real environmental noise varies momentarily and its energy does not distribute evenly in the time-frequency domain. Therefore, segmenting a spectrogram of speech mixed with environmental noise into narrow time-frequency regions will produce low-noise regions in which the signal-to-noise ratio is high. The proposed method estimates F0 from the per...
Genetic noise control via protein oligomerization
Directory of Open Access Journals (Sweden)
Almaas Eivind
2008-11-01
Full Text Available Abstract Background Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamic role of protein-protein interactions. Results We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch, integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast binding-unbinding kinetics among proteins, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its random switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced state from randomly being induced (uninduced. Conclusion The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of regulatory circuits
Fundamental stellar parameters
Wittkowski, M
2004-01-01
I present a discussion of fundamental stellar parameters and their observational determination in the context of interferometric measurements with current and future optical/infrared interferometric facilities. Stellar parameters and the importance of their determination for stellar physics are discussed. One of the primary uses of interferometry in the field of stellar physics is the measurement of the intensity profile across the stellar disk, both as a function of position angle and of wavelength. High-precision fundamental stellar parameters are also derived by characterizations of binary and multiple system using interferometric observations. This topic is discussed in detail elsewhere in these proceedings. Comparison of observed spectrally dispersed center-to-limb intensity variations with models of stellar atmospheres and stellar evolution may result in an improved understanding of key phenomena in stellar astrophysics such as the precise evolutionary effects on the main sequence, the evolution of meta...
Fundamentals of nuclear physics
Takigawa, Noboru
2017-01-01
This book introduces the current understanding of the fundamentals of nuclear physics by referring to key experimental data and by providing a theoretical understanding of principal nuclear properties. It primarily covers the structure of nuclei at low excitation in detail. It also examines nuclear forces and decay properties. In addition to fundamentals, the book treats several new research areas such as non-relativistic as well as relativistic Hartree–Fock calculations, the synthesis of super-heavy elements, the quantum chromodynamics phase diagram, and nucleosynthesis in stars, to convey to readers the flavor of current research frontiers in nuclear physics. The authors explain semi-classical arguments and derivation of its formulae. In these ways an intuitive understanding of complex nuclear phenomena is provided. The book is aimed at graduate school students as well as junior and senior undergraduate students and postdoctoral fellows. It is also useful for researchers to update their knowledge of diver...
Fundamentals of Polarized Light
Mishchenko, Michael
2003-01-01
The analytical and numerical basis for describing scattering properties of media composed of small discrete particles is formed by the classical electromagnetic theory. Although there are several excellent textbooks outlining the fundamentals of this theory, it is convenient for our purposes to begin with a summary of those concepts and equations that are central to the subject of this book and will be used extensively in the following chapters. We start by formulating Maxwell's equations and constitutive relations for time- harmonic macroscopic electromagnetic fields and derive the simplest plane-wave solution that underlies the basic optical idea of a monochromatic parallel beam of light. This solution naturally leads to the introduction of such fundamental quantities as the refractive index and the Stokes parameters. Finally, we define the concept of a quasi-monochromatic beam of light and discuss its implications.
2004-01-01
Discussing what is fundamental in a variety of fields, biologist Richard Dawkins, physicist Gerardus 't Hooft, and mathematician Alain Connes spoke to a packed Main Auditorium at CERN 15 October. Dawkins, Professor of the Public Understanding of Science at Oxford University, explained simply the logic behind Darwinian natural selection, and how it would seem to apply anywhere in the universe that had the right conditions. 't Hooft, winner of the 1999 Physics Nobel Prize, outlined some of the main problems in physics today, and said he thinks physics is so fundamental that even alien scientists from another planet would likely come up with the same basic principles, such as relativity and quantum mechanics. Connes, winner of the 1982 Fields Medal (often called the Nobel Prize of Mathematics), explained how physics is different from mathematics, which he described as a "factory for concepts," unfettered by connection to the physical world. On 16 October, anthropologist Sharon Traweek shared anecdotes from her ...
Variation of fundamental constants
Flambaum, V V
2006-01-01
We present a review of recent works devoted to the variation of the fine structure constant alpha, strong interaction and fundamental masses. There are some hints for the variation in quasar absorption spectra, Big Bang nucleosynthesis, and Oklo natural nuclear reactor data. A very promising method to search for the variation of the fundamental constants consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transition between accidentally degenerate atomic and molecular energy levels. A new idea is to build a ``nuclear'' clock based on the ultraviolet transition between very low excited state and ground state in Thorium nucleus. This may allow to improve sensitivity to the variation up to 10 orders of magnitude! Huge enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feschbach resonance.
Bolčina, Matjaž
2014-01-01
Noise is everywhere. Noise is a sound that makes people stressful and irritate. It often couses sleep disorders and also health problems like different cardiovascular disorders, hearing loss…In most cases traffic noise is the most disturbing. There are different ways to prevent people from traffic noise like building noise barriers and insulation of facades. However noise barriers and insulation of facades do not prevent noise formation, but are lowering existing noise. Another disadvantage i...
Fundamentals of Stochastic Networks
Ibe, Oliver C
2011-01-01
An interdisciplinary approach to understanding queueing and graphical networks In today's era of interdisciplinary studies and research activities, network models are becoming increasingly important in various areas where they have not regularly been used. Combining techniques from stochastic processes and graph theory to analyze the behavior of networks, Fundamentals of Stochastic Networks provides an interdisciplinary approach by including practical applications of these stochastic networks in various fields of study, from engineering and operations management to communications and the physi
Fundamentals of queueing theory
Gross, Donald; Thompson, James M; Harris, Carl M
2013-01-01
Praise for the Third Edition ""This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented.""-IIE Transactions on Operations Engineering Thoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than pre
High voltage engineering fundamentals
Kuffel, E; Hammond, P
1984-01-01
Provides a comprehensive treatment of high voltage engineering fundamentals at the introductory and intermediate levels. It covers: techniques used for generation and measurement of high direct, alternating and surge voltages for general application in industrial testing and selected special examples found in basic research; analytical and numerical calculation of electrostatic fields in simple practical insulation system; basic ionisation and decay processes in gases and breakdown mechanisms of gaseous, liquid and solid dielectrics; partial discharges and modern discharge detectors; and over
Biomedical engineering fundamentals
Bronzino, Joseph D
2014-01-01
Known as the bible of biomedical engineering, The Biomedical Engineering Handbook, Fourth Edition, sets the standard against which all other references of this nature are measured. As such, it has served as a major resource for both skilled professionals and novices to biomedical engineering.Biomedical Engineering Fundamentals, the first volume of the handbook, presents material from respected scientists with diverse backgrounds in physiological systems, biomechanics, biomaterials, bioelectric phenomena, and neuroengineering. More than three dozen specific topics are examined, including cardia
Greg Hall, D
2011-01-01
Session 1 of the 2010 STP/IFSTP Joint Symposium on Toxicologic Neuropathology, titled "Fundamentals of Neurobiology," was organized to provide a foundation for subsequent sessions by presenting essential elements of neuroanatomy and nervous system function. A brief introduction to the session titled "Introduction to Correlative Neurobiology" was provided by Dr. Greg Hall (Eli Lilly and Company, Indianapolis, IN). Correlative neurobiology refers to considerations of the relationships between the highly organized and compartmentalized structure of nervous tissues and the functioning within this system.
Duane Knudson
2007-01-01
DESCRIPTION This book provides a broad and in-depth theoretical and practical description of the fundamental concepts in understanding biomechanics in the qualitative analysis of human movement. PURPOSE The aim is to bring together up-to-date biomechanical knowledge with expert application knowledge. Extensive referencing for students is also provided. FEATURES This textbook is divided into 12 chapters within four parts, including a lab activities section at the end. The division is as follow...
Fundamentals of linear algebra
Dash, Rajani Ballav
2008-01-01
FUNDAMENTALS OF LINEAR ALGEBRA is a comprehensive Text Book, which can be used by students and teachers of All Indian Universities. The Text has easy, understandable form and covers all topics of UGC Curriculum. There are lots of worked out examples which helps the students in solving the problems without anybody's help. The Problem sets have been designed keeping in view of the questions asked in different examinations.
Neutrons and Fundamental Symmetries
Energy Technology Data Exchange (ETDEWEB)
Plaster, Bradley [Univ. of Kentucky, Lexington, KY (United States). Dept. of Physics and Astronomy
2016-01-11
The research supported by this project addressed fundamental open physics questions via experiments with subatomic particles. In particular, neutrons constitute an especially ideal “laboratory” for fundamental physics tests, as their sensitivities to the four known forces of nature permit a broad range of tests of the so-called “Standard Model”, our current best physics model for the interactions of subatomic particles. Although the Standard Model has been a triumphant success for physics, it does not provide satisfactory answers to some of the most fundamental open questions in physics, such as: are there additional forces of nature beyond the gravitational, electromagnetic, weak nuclear, and strong nuclear forces?, or why does our universe consist of more matter than anti-matter? This project also contributed significantly to the training of the next generation of scientists, of considerable value to the public. Young scientists, ranging from undergraduate students to graduate students to post-doctoral researchers, made significant contributions to the work carried out under this project.
Burov, Alexey
Fundamental science is a hard, long-term human adventure that has required high devotion and social support, especially significant in our epoch of Mega-science. The measure of this devotion and this support expresses the real value of the fundamental science in public opinion. Why does fundamental science have value? What determines its strength and what endangers it? The dominant answer is that the value of science arises out of curiosity and is supported by the technological progress. Is this really a good, astute answer? When trying to attract public support, we talk about the ``mystery of the universe''. Why do these words sound so attractive? What is implied by and what is incompatible with them? More than two centuries ago, Immanuel Kant asserted an inseparable entanglement between ethics and metaphysics. Thus, we may ask: which metaphysics supports the value of scientific cognition, and which does not? Should we continue to neglect the dependence of value of pure science on metaphysics? If not, how can this issue be addressed in the public outreach? Is the public alienated by one or another message coming from the face of science? What does it mean to be politically correct in this sort of discussion?
Critical Petermann K factor for intensity noise squeezing
van der Lee, A.M.; van Druten, N.J.; van Exter, M.P.; Woerdman, J.P.; Poizat, J.P.; Grangier, P.
2000-01-01
We investigate the impact of the Petermann-excess-noise factor K >= 1 on the possibility of intensity noise squeezing of laser light below the standard quantum limit. Using an N-mode model, we show that squeezing is limited to a floor level of 2(K-1) times the shot noise limit. Thus, even a modest P
Institute of Scientific and Technical Information of China (English)
毛虎; 吴德伟
2014-01-01
为了提高带限高斯噪声对GPS军码信号的干扰效率,以 GPS接收机的码跟踪误差作为干扰效果评估指标,对其特定干信比下的干扰频偏和干扰带宽进行优化确定。在分析 GPS P(Y)码和M码信号功率谱特点的基础上,根据非相干超前减滞后处理码跟踪环路工作原理,理论推导得到干扰频偏和干扰带宽与码跟踪误差的解析式。基于实际情况设置接收机码环参数,分别定量地仿真计算出不同干信比下针对 P(Y)码和 M码信号的高效干扰频偏和干扰带宽。以造成码环失锁所需干信比最小为主要评判准则,同时考虑干扰易实施性和频域滤波等因素的影响,通过综合比较得出：当干信比在50~60 dB 范围内时,针对 P(Y)码信号的干扰频偏和干扰带宽分别设置为0和8.8 MHz,针对正弦 BOC 和余弦 BOC 调制的 M码信号的干扰频偏分别设置为9.833 MHz和10.9 MHz,干扰带宽统一设置为10 MHz。%For the sake of improving j amming efficiency of band-limited Gaussian noise to GPS military sig-nals,this paper use code tracking error of GPS receiver as the j amming effect evaluation index to optimize band-limited Gaussian noise jamming frequency offset and bandwidth under given JSR.On the basis of a-nalysis GPS P(Y)code and M code signal power spectrum characteristics,according to operating principle of non-coherent early-minus-late power DLL,the expression between j amming frequency offset and band-width with code tracking error is obtained through theoretical derivation.Based on practical condition to set the DLL parameters of receiver,the efficient band-limited Gaussian noise j amming frequency offset and bandwidth to P(Y)code and M code signal is simulated and calculated quantitatively under the different JSR respectively.Taking the minimum JSR of causing DLL lock-lose as primary opting criterion,at the same time to consider the influence of j amming implement complexity and frequency domain
Interferometric Constraints on Quantum Geometrical Shear Noise Correlations
Energy Technology Data Exchange (ETDEWEB)
Chou, Aaron; Glass, Henry; Gustafson, H. Richard; Hogan, Craig J.; Kamai, Brittany L.; Kwon, Ohkyung; Lanza, Robert; McCuller, Lee; Meyer, Stephan S.; Richardson, Jonathan W.; Stoughton, Chris; Tomlin, Ray; Weiss, Rainer
2017-03-24
Final measurements and analysis are reported from the first-generation Holometer, the first instrument capable of measuring correlated variations in space-time position at strain noise power spectral densities smaller than a Planck time. The apparatus consists of two co-located, but independent and isolated, 40 m power-recycled Michelson interferometers, whose outputs are cross-correlated to 25 MHz. The data are sensitive to correlations of differential position across the apparatus over a broad band of frequencies up to and exceeding the inverse light crossing time, 7.6 MHz. By measuring with Planck precision the correlation of position variations at spacelike separations, the Holometer searches for faint, irreducible correlated position noise backgrounds predicted by some models of quantum space-time geometry. The first-generation optical layout is sensitive to quantum geometrical noise correlations with shear symmetry---those that can be interpreted as a fundamental noncommutativity of space-time position in orthogonal directions. General experimental constraints are placed on parameters of a set of models of spatial shear noise correlations, with a sensitivity that exceeds the Planck-scale holographic information bound on position states by a large factor. This result significantly extends the upper limits placed on models of directional noncommutativity by currently operating gravitational wave observatories.
Interferometric constraints on quantum geometrical shear noise correlations
Chou, Aaron; Glass, Henry; Gustafson, H. Richard; Hogan, Craig J.; Kamai, Brittany L.; Kwon, Ohkyung; Lanza, Robert; McCuller, Lee; Meyer, Stephan S.; Richardson, Jonathan W.; Stoughton, Chris; Tomlin, Ray; Weiss, Rainer
2017-08-01
Final measurements and analysis are reported from the first-generation Holometer, the first instrument capable of measuring correlated variations in space-time position at strain noise power spectral densities smaller than a Planck time. The apparatus consists of two co-located, but independent and isolated, 40 m power-recycled Michelson interferometers, whose outputs are cross-correlated to 25 MHz. The data are sensitive to correlations of differential position across the apparatus over a broad band of frequencies up to and exceeding the inverse light crossing time, 7.6 MHz. By measuring with Planck precision the correlation of position variations at spacelike separations, the Holometer searches for faint, irreducible correlated position noise backgrounds predicted by some models of quantum space-time geometry. The first-generation optical layout is sensitive to quantum geometrical noise correlations with shear symmetry—those that can be interpreted as a fundamental noncommutativity of space-time position in orthogonal directions. General experimental constraints are placed on parameters of a set of models of spatial shear noise correlations, with a sensitivity that exceeds the Planck-scale holographic information bound on position states by a large factor. This result significantly extends the upper limits placed on models of directional noncommutativity by currently operating gravitational wave observatories.
Consumer oriented product noise testing
Blomberg, Les
2005-09-01
This paper explores the need for product noise measurements and how best to meet that need in the near future. Currently there is only a small market place for quieter consumer products. This is not because of lack of interest. No one really wants to announce to everyone in their house that they just flushed the toilet, few really want the entire neighborhood to know they are mowing their yard, etc. The small market place is primarily due to a lack of regulations on product noise, a lack of information easily available to consumers about which products are quieter, and market consolidation resulting in fewer manufacturers, most of whom are unwilling to emphasize their quieter products at the risk of eroding sales of their noisier ones (that currently have greater market share). In the absence of the EPA fulfilling its statutory requirement to regulate and label product noise under the Noise Control Act of 1972, and with the unwillingness of most industries to voluntarily publish accurate product noise data, there is a significant role for ``Consumer Oriented Product Noise Testing.'' This paper explores the Noise Pollution Clearinghouse's ongoing and planned product noise testing, evaluating its advantages, disadvantages, and limitations.
Spin-noise correlations and spin-noise exchange driven by low-field spin-exchange collisions
Dellis, A. T.; Loulakis, M.; Kominis, I. K.
2014-09-01
The physics of spin-exchange collisions have fueled several discoveries in fundamental physics and numerous applications in medical imaging and nuclear magnetic resonance. We report on the experimental observation and theoretical justification of spin-noise exchange, the transfer of spin noise from one atomic species to another. The signature of spin-noise exchange is an increase of the total spin-noise power at low magnetic fields, on the order of 1 mG, where the two-species spin-noise resonances overlap. The underlying physical mechanism is the two-species spin-noise correlation induced by spin-exchange collisions.
Sample size cognizant detection of signals in white noise
Rao, N Raj
2007-01-01
The detection and estimation of signals in noisy, limited data is a problem of interest to many scientific and engineering communities. We present a computationally simple, sample eigenvalue based procedure for estimating the number of high-dimensional signals in white noise when there are relatively few samples. We highlight a fundamental asymptotic limit of sample eigenvalue based detection of weak high-dimensional signals from a limited sample size and discuss its implication for the detection of two closely spaced signals. This motivates our heuristic definition of the 'effective number of identifiable signals.' Numerical simulations are used to demonstrate the consistency of the algorithm with respect to the effective number of signals and the superior performance of the algorithm with respect to Wax and Kailath's "asymptotically consistent" MDL based estimator.
Institute of Scientific and Technical Information of China (English)
Zhang Qi-Cheng; Ni Yi; Xu Duan-Yi; Hu Heng
2006-01-01
The recording density of multilevel photochromic memory is limited by the signal-to-noise ratio (SNR) of the readout signal. In this paper, shot noise and material noise are investigated through theoretical analysis of SNR. When the bandwidth of a system is less than 1MHz, the material noise takes a prominent position; when the bandwidth of the system is more than 10MHz, the shot noise becomes dominant. The thickness of recording layer can be optimized to maximize the SNR and reduce the influence of the bandwidth of the system on SNR.
Quantum Limits of Space-to-Ground Optical Communications
Hemmati, H.; Dolinar, S.
2012-01-01
For a pure loss channel, the ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light): (1) Capacity-achieving receiver (measurement) is yet to be determined. (2) Heterodyne detection approaches the ultimate capacity at high mean photon numbers. (3) Photon-counting approaches the ultimate capacity at low mean photon numbers. A number of current technology limits drive the achievable performance of free-space communication links. Approaching fundamental limits in the bandwidth-limited regime: (1) Heterodyne detection with high-order coherent-state modulation approaches ultimate limits. SOA improvements to laser phase noise, adaptive optics systems for atmospheric transmission would help. (2) High-order intensity modulation and photon-counting can approach heterodyne detection within approximately a factor of 2. This may have advantages over coherent detection in the presence of turbulence. Approaching fundamental limits in the photon-limited regime (1) Low-duty cycle binary coherent-state modulation (OOK, PPM) approaches ultimate limits. SOA improvements to laser extinction ratio, receiver dark noise, jitter, and blocking would help. (2) In some link geometries (near field links) number-state transmission could improve over coherent-state transmission
Quantum Limits of Space-to-Ground Optical Communications
Hemmati, H.; Dolinar, S.
2012-01-01
For a pure loss channel, the ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light): (1) Capacity-achieving receiver (measurement) is yet to be determined. (2) Heterodyne detection approaches the ultimate capacity at high mean photon numbers. (3) Photon-counting approaches the ultimate capacity at low mean photon numbers. A number of current technology limits drive the achievable performance of free-space communication links. Approaching fundamental limits in the bandwidth-limited regime: (1) Heterodyne detection with high-order coherent-state modulation approaches ultimate limits. SOA improvements to laser phase noise, adaptive optics systems for atmospheric transmission would help. (2) High-order intensity modulation and photon-counting can approach heterodyne detection within approximately a factor of 2. This may have advantages over coherent detection in the presence of turbulence. Approaching fundamental limits in the photon-limited regime (1) Low-duty cycle binary coherent-state modulation (OOK, PPM) approaches ultimate limits. SOA improvements to laser extinction ratio, receiver dark noise, jitter, and blocking would help. (2) In some link geometries (near field links) number-state transmission could improve over coherent-state transmission
Information security fundamentals
Blackley, John A; Peltier, Justin
2004-01-01
Effective security rules and procedures do not exist for their own sake-they are put in place to protect critical assets, thereby supporting overall business objectives. Recognizing security as a business enabler is the first step in building a successful program.Information Security Fundamentals allows future security professionals to gain a solid understanding of the foundations of the field and the entire range of issues that practitioners must address. This book enables students to understand the key elements that comprise a successful information security program and eventually apply thes
Directory of Open Access Journals (Sweden)
Carlos A. Robles Corbalá
2015-12-01
Full Text Available En este artículo se aborda un problema clásico para poder detectar si dos espacios topológicos son homeomorfos o no. Para lo cual a cada espacio topológico se le asocia un grupo algebraico, de tal suerte que si los espacios son homeomorfos, entonces los grupos asociados serán isomorfos. Se presenta una construcción del grupo fundamental de un espacio topológico y se enfoca en demostrar que efectivamente es un grupo.
Morris, Carla C
2015-01-01
Fundamentals of Calculus encourages students to use power, quotient, and product rules for solutions as well as stresses the importance of modeling skills. In addition to core integral and differential calculus coverage, the book features finite calculus, which lends itself to modeling and spreadsheets. Specifically, finite calculus is applied to marginal economic analysis, finance, growth, and decay. Includes: Linear Equations and FunctionsThe DerivativeUsing the Derivative Exponential and Logarithmic Functions Techniques of DifferentiationIntegral CalculusIntegration TechniquesFunctions
Fundamentals of engineering electromagnetism
Energy Technology Data Exchange (ETDEWEB)
Kim, Nam; Yoon, Youngro; Jun, Sukhee; Jun, Hoin
2004-08-15
It indicates fundamentals of engineering electromagnetism. It mentions electromagnetic field model of introduction and International system of units and universal constant, Vector analysis with summary and orthogonal coordinate systems, electrostatic field on Coulomb's law and Gauss's law, electrostatic energy and strength, steady state current with Ohm's law and Joule's law and calculation of resistance, crystallite field with Vector's electrostatic potential, Biot-Savart law and application and Magnetic Dipole, time-Savart and Maxwell equation with potential function and Faraday law of electromagnetic induction, plane electromagnetic wave, transmission line, a wave guide and cavity resonator and antenna arrangement.
Fundamentals of attosecond optics
Chang, Zenghu
2011-01-01
Attosecond optical pulse generation, along with the related process of high-order harmonic generation, is redefining ultrafast physics and chemistry. A practical understanding of attosecond optics requires significant background information and foundational theory to make full use of these cutting-edge lasers and advance the technology toward the next generation of ultrafast lasers. Fundamentals of Attosecond Optics provides the first focused introduction to the field. The author presents the underlying concepts and techniques required to enter the field, as well as recent research advances th
Fundamentals of microwave photonics
Urick, V J; McKinney , Jason D
2015-01-01
A comprehensive resource to designing andconstructing analog photonic links capable of high RFperformanceFundamentals of Microwave Photonics provides acomprehensive description of analog optical links from basicprinciples to applications. The book is organized into fourparts. The first begins with a historical perspective of microwavephotonics, listing the advantages of fiber optic links anddelineating analog vs. digital links. The second section coversbasic principles associated with microwave photonics in both the RFand optical domains. The third focuses on analog modulationformats-starti
Mathematical analysis fundamentals
Bashirov, Agamirza
2014-01-01
The author's goal is a rigorous presentation of the fundamentals of analysis, starting from elementary level and moving to the advanced coursework. The curriculum of all mathematics (pure or applied) and physics programs include a compulsory course in mathematical analysis. This book will serve as can serve a main textbook of such (one semester) courses. The book can also serve as additional reading for such courses as real analysis, functional analysis, harmonic analysis etc. For non-math major students requiring math beyond calculus, this is a more friendly approach than many math-centric o
Fundamentals of Project Management
Heagney, Joseph
2011-01-01
With sales of more than 160,000 copies, Fundamentals of Project Management has helped generations of project managers navigate the ins and outs of every aspect of this complex discipline. Using a simple step-by-step approach, the book is the perfect introduction to project management tools, techniques, and concepts. Readers will learn how to: ò Develop a mission statement, vision, goals, and objectives ò Plan the project ò Create the work breakdown structure ò Produce a workable schedule ò Understand earned value analysis ò Manage a project team ò Control and evaluate progress at every stage.
Fundamental concepts of mathematics
Goodstein, R L
Fundamental Concepts of Mathematics, 2nd Edition provides an account of some basic concepts in modern mathematics. The book is primarily intended for mathematics teachers and lay people who wants to improve their skills in mathematics. Among the concepts and problems presented in the book include the determination of which integral polynomials have integral solutions; sentence logic and informal set theory; and why four colors is enough to color a map. Unlike in the first edition, the second edition provides detailed solutions to exercises contained in the text. Mathematics teachers and people
Fundamentals of semiconductor devices
Lindmayer, Joseph
1965-01-01
Semiconductor properties ; semiconductor junctions or diodes ; transistor fundamentals ; inhomogeneous impurity distributions, drift or graded-base transistors ; high-frequency properties of transistors ; band structure of semiconductors ; high current densities and mechanisms of carrier transport ; transistor transient response and recombination processes ; surfaces, field-effect transistors, and composite junctions ; additional semiconductor characteristics ; additional semiconductor devices and microcircuits ; more metal, insulator, and semiconductor combinations for devices ; four-pole parameters and configuration rotation ; four-poles of combined networks and devices ; equivalent circuits ; the error function and its properties ; Fermi-Dirac statistics ; useful physical constants.
Fundamental of biomedical engineering
Sawhney, GS
2007-01-01
About the Book: A well set out textbook explains the fundamentals of biomedical engineering in the areas of biomechanics, biofluid flow, biomaterials, bioinstrumentation and use of computing in biomedical engineering. All these subjects form a basic part of an engineer''s education. The text is admirably suited to meet the needs of the students of mechanical engineering, opting for the elective of Biomedical Engineering. Coverage of bioinstrumentation, biomaterials and computing for biomedical engineers can meet the needs of the students of Electronic & Communication, Electronic & Instrumenta
Franc, Jean-Pierre
2005-01-01
The present book is aimed at providing a comprehensive presentation of cavitation phenomena in liquid flows. It is further backed up by the experience, both experimental and theoretical, of the authors whose expertise has been internationally recognized. A special effort is made to place the various methods of investigation in strong relation with the fundamental physics of cavitation, enabling the reader to treat specific problems independently. Furthermore, it is hoped that a better knowledge of the cavitation phenomenon will allow engineers to create systems using it positively. Examples in the literature show the feasibility of this approach.
Saleh, Bahaa E A
2007-01-01
Now in a new full-color edition, Fundamentals of Photonics, Second Edition is a self-contained and up-to-date introductory-level textbook that thoroughly surveys this rapidly expanding area of engineering and applied physics. Featuring a logical blend of theory and applications, coverage includes detailed accounts of the primary theories of light, including ray optics, wave optics, electromagnetic optics, and photon optics, as well as the interaction of photons and atoms, and semiconductor optics. Presented at increasing levels of complexity, preliminary sections build toward more advan
Nanomachines fundamentals and applications
Wang, Joseph
2013-01-01
This first-hand account by one of the pioneers of nanobiotechnology brings together a wealth of valuable material in a single source. It allows fascinating insights into motion at the nanoscale, showing how the proven principles of biological nanomotors are being transferred to artificial nanodevices.As such, the author provides engineers and scientists with the fundamental knowledge surrounding the design and operation of biological and synthetic nanomotors and the latest advances in nanomachines. He addresses such topics as nanoscale propulsions, natural biomotors, molecular-scale machin
Electronic circuits fundamentals & applications
Tooley, Mike
2015-01-01
Electronics explained in one volume, using both theoretical and practical applications.New chapter on Raspberry PiCompanion website contains free electronic tools to aid learning for students and a question bank for lecturersPractical investigations and questions within each chapter help reinforce learning Mike Tooley provides all the information required to get to grips with the fundamentals of electronics, detailing the underpinning knowledge necessary to appreciate the operation of a wide range of electronic circuits, including amplifiers, logic circuits, power supplies and oscillators. The
Mapping Urban Environmental Noise Using Smartphones
Directory of Open Access Journals (Sweden)
Jinbo Zuo
2016-10-01
Full Text Available Noise mapping is an effective method of visualizing and accessing noise pollution. In this paper, a noise-mapping method based on smartphones to effectively and easily measure environmental noise is proposed. By using this method, a noise map of an entire area can be created using limited measurement data. To achieve the measurement with certain precision, a set of methods was designed to calibrate the smartphones. Measuring noise with mobile phones is different from the traditional static observations. The users may be moving at any time. Therefore, a method of attaching an additional microphone with a windscreen is proposed to reduce the wind effect. However, covering an entire area is impossible. Therefore, an interpolation method is needed to achieve full coverage of the area. To reduce the influence of spatial heterogeneity and improve the precision of noise mapping, a region-based noise-mapping method is proposed in this paper, which is based on the distribution of noise in different region types tagged by volunteers, to interpolate and combine them to create a noise map. To validate the effect of the method, a comparison of the interpolation results was made to analyse our method and the ordinary Kriging method. The result shows that our method is more accurate in reflecting the local distribution of noise and has better interpolation precision. We believe that the proposed noise-mapping method is a feasible and low-cost noise-mapping solution.
Fundamentals of nanomechanical resonators
Schmid, Silvan; Roukes, Michael Lee
2016-01-01
This authoritative book introduces and summarizes the latest models and skills required to design and optimize nanomechanical resonators, taking a top-down approach that uses macroscopic formulas to model the devices. The authors cover the electrical and mechanical aspects of nano electromechanical system (NEMS) devices. The introduced mechanical models are also key to the understanding and optimization of nanomechanical resonators used e.g. in optomechanics. Five comprehensive chapters address: The eigenmodes derived for the most common continuum mechanical structures used as nanomechanical resonators; The main sources of energy loss in nanomechanical resonators; The responsiveness of micro and nanomechanical resonators to mass, forces, and temperature; The most common underlying physical transduction mechanisms; The measurement basics, including amplitude and frequency noise. The applied approach found in this book is appropriate for engineering students and researchers working with micro and nanomechanical...
Prewhitening for Narrow-Band Noise in Subspace Methods for Noise Reduction
DEFF Research Database (Denmark)
Hansen, Per Christian; Jensen, Søren Holdt
2004-01-01
A fundamental issue in connection with subspace methods for noise reduction is that the covariance matrix for the noise is required to have full rank, in order for the prewhitening step to be defined. However, there are important cases where this requirement is not fulfilled, typically when...... that works also for rank deficient noise. We also demonstrate how to formulate this algorithm by means of a quotient ULV decomposition, which allows for faster computation and updating. Finally we apply our algorithm to a problem involving a speech signal contaminated by narrow-band noise....
Cardone, V F; Diaferio, A; Tortora, C; Molinaro, R
2010-01-01
Modified Newtonian Dynamics (MOND) has been shown to be able to fit spiral galaxy rotation curves as well as giving a theoretical foundation for empirically determined scaling relations, such as the Tully - Fisher law, without the need for a dark matter halo. As a complementary analysis, one should investigate whether MOND can also reproduce the dynamics of early - type galaxies (ETGs) without dark matter. As a first step, we here show that MOND can indeed fit the observed central velocity dispersion $\\sigma_0$ of a large sample of ETGs assuming a simple MOND interpolating functions and constant anisotropy. We also show that, under some assumptions on the luminosity dependence of the Sersic n parameter and the stellar M/L ratio, MOND predicts a fundamental plane for ETGs : a log - linear relation among the effective radius $R_{eff}$, $\\sigma_0$ and the mean effective intensity $\\langle I_e \\rangle$. However, we predict a tilt between the observed and the MOND fundamental planes.
Pisacane, Vincent L.
2005-06-01
Fundamentals of Space Systems was developed to satisfy two objectives: the first is to provide a text suitable for use in an advanced undergraduate or beginning graduate course in both space systems engineering and space system design. The second is to be a primer and reference book for space professionals wishing to broaden their capabilities to develop, manage the development, or operate space systems. The authors of the individual chapters are practicing engineers that have had extensive experience in developing sophisticated experimental and operational spacecraft systems in addition to having experience teaching the subject material. The text presents the fundamentals of all the subsystems of a spacecraft missions and includes illustrative examples drawn from actual experience to enhance the learning experience. It included a chapter on each of the relevant major disciplines and subsystems including space systems engineering, space environment, astrodynamics, propulsion and flight mechanics, attitude determination and control, power systems, thermal control, configuration management and structures, communications, command and telemetry, data processing, embedded flight software, survuvability and reliability, integration and test, mission operations, and the initial conceptual design of a typical small spacecraft mission.
Zhou, Xiaoyan; Zhang, Lin; Pang, Wei
2016-08-01
Optical microcavity sensors using intensity detection open up the possibility to realize fully integrated high-performance sensing devices, which are significant for both fundamental study of molecular interaction and rapid disease diagnosis. Although the performance of microresonator-based sensors has been studied focusing on the resonance-tracking method, the situation can be much different for intensity-detection sensors. Here we conducted a systematically investigation on the noises sources in intensity detection scheme and their influences on key performance parameters, e.g., signal-to-noise ratio (SNR), limit-of-detection (LOD), and detection range, for various sensors configurations. Especially, the trade-off between SNR and LOD is identified and theoretically analyzed. With experiment noises taken into consideration, our work aims to provide design guidelines for integrated microresonator sensors with optimized performance.
Extending the square root method to account for additive forecast noise in ensemble methods
Raanes, Patrick N; Bertino, Laurent
2015-01-01
A square root approach is considered for the problem of accounting for model noise in the forecast step of the ensemble Kalman filter (EnKF) and related algorithms. The primary aim is to replace the method of simulated, pseudo-random, additive noise so as to eliminate the associated sampling errors. The core method is based on the analysis step of ensemble square root filters, and consists in the deterministic computation of a transform matrix. The theoretical advantages regarding dynamical consistency are surveyed, applying equally well to the square root method in the analysis step. A fundamental problem due to the limited size of the ensemble subspace is discussed, and novel solutions that complement the core method are suggested and studied. Benchmarks from twin experiments with simple, low-order dynamics indicate improved performance over standard approaches such as additive, simulated noise and multiplicative inflation.
Lieu, Richard
2016-01-01
A hierarchy of statistics of increasing sophistication and accuracy is proposed, to exploit an interesting and fundamental arithmetic structure in the photon bunching noise of incoherent light of large photon occupation number, with the purpose of suppressing the noise and rendering a more reliable and unbiased measurement of the light intensity. The method does not require any new hardware, rather it operates at the software level, with the help of high precision computers, to reprocess the intensity time series of the incident light to create a new series with smaller bunching noise coherence length. The ultimate accuracy improvement of this method of flux measurement is limited by the timing resolution of the detector, the precision of the computer in manipulating numbers, and the photon occupation number of the beam (the higher the photon number the better the performance). The principal application is sensitivity enhancement of radio astronomical observations.
Beam simulations with initial bunch noise in superconducting RF proton linacs
Tückmantel, J
2010-01-01
Circular machines are plagued by coupled bunch instabilities (CBI), driven by impedance peaks, where then all cavity higher order modes (HOMs) are possible drivers. Limiting the CBI growth rate is the fundamental reason that all superconducting rf cavities in circular machines are equipped with HOM dampers. The question arises if for similar reasons HOM damping would not be imperative also in high current superconducting rf proton linacs. Therefore we have simulated the longitudinal bunched beam dynamics in such machines, also including charge and position noise on the injected bunches. Simulations were executed for a generic linac with properties close to the planned SPL at CERN, SNS, or Project X at FNAL. It was found that with strong bunch noise and monopole HOMs with high Qext large beam scatter, possibly exceeding the admittance of a receiving machine, cannot be excluded. A transverse simulation shows similar requirements. Therefore including initial bunch noise in any beam dynamic study on superconducti...
Noise Filtering in Communication with Chaos
Energy Technology Data Exchange (ETDEWEB)
Rosa, E. Jr. [Institute for Plasma Research, University of Maryland, College Park, Maryland 20742 (United States); Hayes, S. [Nonlinear Devices Corporation, 8701 Georgia Avenue Suite 501, Silver Spring, Maryland 20910 (United States); Grebogi, C. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Potsdam, PF 601553, D-14415 Potsdam (Germany)
1997-02-01
A method, based on fundamental properties of chaotic dynamics, is devised for filtering {ital in-band} noise of an incoming signal generated by a chaotic oscillator. Initially the 2xmod1 map is used to illustrate the procedure and then the method is applied to recover the message encoded in a realistic chaotic signal, after the transmitted signal has been contaminated with noise. {copyright} {ital 1997} {ital The American Physical Society}
Fundamentals of reversible flowchart languages
DEFF Research Database (Denmark)
Yokoyama, Tetsuo; Axelsen, Holger Bock; Glück, Robert
2016-01-01
. Although reversible flowcharts are superficially similar to classical flowcharts, there are crucial differences: atomic steps are limited to locally invertible operations, and join points require an explicit orthogonalizing conditional expression. Despite these constraints, we show that reversible......Abstract This paper presents the fundamentals of reversible flowcharts. They are intended to naturally represent the structure and control flow of reversible (imperative) programming languages in a simple computation model, in the same way classical flowcharts do for conventional languages......, structured reversible flowcharts are as expressive as unstructured ones, as shown by a reversible version of the classic Structured Program Theorem. We illustrate how reversible flowcharts can be concretized with two example programming languages, complete with syntax and semantics: a low-level unstructured...
Materials Fundamentals of Gate Dielectrics
Demkov, Alexander A
2006-01-01
This book presents materials fundamentals of novel gate dielectrics that are being introduced into semiconductor manufacturing to ensure the continuous scalling of the CMOS devices. This is a very fast evolving field of research so we choose to focus on the basic understanding of the structure, thermodunamics, and electronic properties of these materials that determine their performance in device applications. Most of these materials are transition metal oxides. Ironically, the d-orbitals responsible for the high dielectric constant cause sever integration difficulties thus intrinsically limiting high-k dielectrics. Though new in the electronics industry many of these materials are wel known in the field of ceramics, and we describe this unique connection. The complexity of the structure-property relations in TM oxides makes the use of the state of the art first-principles calculations necessary. Several chapters give a detailed description of the modern theory of polarization, and heterojunction band discont...
OPTIMAL INVESTMENT WITH NOISE TRADING RISK
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
This paper investigates the optimal dynamic investment for an investor who maximizes constant absolute risk aversion(CARA)utility in a discrete-time market with a riskfree bond and a risky stock.The risky stock is assumed to present both the dividend risk and the price risk.With our assumptions,the dividend risk is equivalent to fundamental risk,and the price risk is equivalent to the noise trading risk.The analytical expression for the optimal investment strategy is obtained by dynamic programming.The main result in this paper highlights the importance of differentiating between noise trading risk and fundamental risk for the optimal dynamic investment.
A low noise interface circuit design of micro-machined gyroscope
Fu, Qiang; Di, Xipeng; Yin, Liang; Liu, Xiaowei
2017-07-01
The analyses of MEMS gyroscope interface circuit on thermal noise, 1/f noise and phase noise are made in this paper. A closed-loop differential driving circuit and a low-noise differential detecting circuit based on the high frequency modulation are designed to limit the noise. The interface chip is implemented in a standard 0.5 μm CMOS process. The test results show that the resolution of sensitive capacity can reach to 6.47 × 10-20 F at the bandwidth of 60 Hz. The measuring range is ± 200°/s and the nonlinearity is 310 ppm. The output noise density is 5.8^\\circ/({{h}}\\cdot \\sqrt{{Hz}}). The angular random walk (allen-variance) is 0.092^\\circ/\\sqrt{{{h}}} and the bias instability is 2.63°/h. Project supported by the National Natural Science Foundation of China (No. 61204121), the National Hi-Tech Research and Development Program of China (No. 2013AA041107), and the Fundamental Research Funds for the Central Universities (No. HIT.NSRIF.2013040).
Digital Fourier analysis fundamentals
Kido, Ken'iti
2015-01-01
This textbook is a thorough, accessible introduction to digital Fourier analysis for undergraduate students in the sciences. Beginning with the principles of sine/cosine decomposition, the reader walks through the principles of discrete Fourier analysis before reaching the cornerstone of signal processing: the Fast Fourier Transform. Saturated with clear, coherent illustrations, "Digital Fourier Analysis - Fundamentals" includes practice problems and thorough Appendices for the advanced reader. As a special feature, the book includes interactive applets (available online) that mirror the illustrations. These user-friendly applets animate concepts interactively, allowing the user to experiment with the underlying mathematics. For example, a real sine signal can be treated as a sum of clockwise and counter-clockwise rotating vectors. The applet illustration included with the book animates the rotating vectors and the resulting sine signal. By changing parameters such as amplitude and frequency, the reader ca...
Fundamentals of quantum mechanics
House, J E
2017-01-01
Fundamentals of Quantum Mechanics, Third Edition is a clear and detailed introduction to quantum mechanics and its applications in chemistry and physics. All required math is clearly explained, including intermediate steps in derivations, and concise review of the math is included in the text at appropriate points. Most of the elementary quantum mechanical models-including particles in boxes, rigid rotor, harmonic oscillator, barrier penetration, hydrogen atom-are clearly and completely presented. Applications of these models to selected “real world” topics are also included. This new edition includes many new topics such as band theory and heat capacity of solids, spectroscopy of molecules and complexes (including applications to ligand field theory), and small molecules of astrophysical interest.
Fundamental partial compositeness
Sannino, Francesco
2016-01-01
We construct renormalizable Standard Model extensions, valid up to the Planck scale, that give a composite Higgs from a new fundamental strong force acting on fermions and scalars. Yukawa interactions of these particles with Standard Model fermions realize the partial compositeness scenario. Successful models exist because gauge quantum numbers of Standard Model fermions admit a minimal enough 'square root'. Furthermore, right-handed SM fermions have an SU(2)$_R$-like structure, yielding a custodially-protected composite Higgs. Baryon and lepton numbers arise accidentally. Standard Model fermions acquire mass at tree level, while the Higgs potential and flavor violations are generated by quantum corrections. We further discuss accidental symmetries and other dynamical features stemming from the new strongly interacting scalars. If the same phenomenology can be obtained from models without our elementary scalars, they would reappear as composite states.
Lasers Fundamentals and Applications
Thyagarajan, K
2010-01-01
Lasers: Fundamentals and Applications, serves as a vital textbook to accompany undergraduate and graduate courses on lasers and their applications. Ever since their invention in 1960, lasers have assumed tremendous importance in the fields of science, engineering and technology because of their diverse uses in basic research and countless technological applications. This book provides a coherent presentation of the basic physics behind the way lasers work, and presents some of their most important applications in vivid detail. After reading this book, students will understand how to apply the concepts found within to practical, tangible situations. This textbook includes worked-out examples and exercises to enhance understanding, and the preface shows lecturers how to most beneficially match the textbook with their course curricula. The book includes several recent Nobel Lectures, which will further expose students to the emerging applications and excitement of working with lasers. Students who study lasers, ...
Fundamentals of Structural Engineering
Connor, Jerome J
2013-01-01
Fundamentals of Structural Engineering provides a balanced, seamless treatment of both classic, analytic methods and contemporary, computer-based techniques for conceptualizing and designing a structure. The book’s principle goal is to foster an intuitive understanding of structural behavior based on problem solving experience for students of civil engineering and architecture who have been exposed to the basic concepts of engineering mechanics and mechanics of materials. Making it distinct from many other undergraduate textbooks, the authors of this text recognize the notion that engineers reason about behavior using simple models and intuition they acquire through problem solving. The approach adopted in this text develops this type of intuition by presenting extensive, realistic problems and case studies together with computer simulation, which allows rapid exploration of how a structure responds to changes in geometry and physical parameters. This book also: Emphasizes problem-based understanding of...
Fundamentals of sustainable neighbourhoods
Friedman, Avi
2015-01-01
This book introduces architects, engineers, builders, and urban planners to a range of design principles of sustainable communities and illustrates them with outstanding case studies. Drawing on the author’s experience as well as local and international case studies, Fundamentals of Sustainable Neighbourhoods presents planning concepts that minimize developments' carbon footprint through compact communities, adaptable and expandable dwellings, adaptable landscapes, and smaller-sized yet quality-designed housing. This book also: Examines in-depth global strategies for minimizing the residential carbon footprint, including district heating, passive solar gain, net-zero residences, as well as preserving the communities' natural assets Reconsiders conceptual approaches in building design and urban planning to promote a better connection between communities and nature Demonstrates practical applications of green architecture Focuses on innovative living spaces in urban environments
Yen, William M; Yamamoto, Hajime
2006-01-01
Drawing from the second edition of the best-selling Handbook of Phosphors, Fundamentals of Phosphors covers the principles and mechanisms of luminescence in detail and surveys the primary phosphor materials as well as their optical properties. The book addresses cutting-edge developments in phosphor science and technology including oxynitride phosphors and the impact of lanthanide level location on phosphor performance.Beginning with an explanation of the physics underlying luminescence mechanisms in solids, the book goes on to interpret various luminescence phenomena in inorganic and organic materials. This includes the interpretation of the luminescence of recently developed low-dimensional systems, such as quantum wells and dots. The book also discusses the excitation mechanisms by cathode-ray and ionizing radiation and by electric fields to produce electroluminescence. The book classifies phosphor materials according to the type of luminescence centers employed or the class of host materials used and inte...
Superconductivity fundamentals and applications
Buckel, Werner
2004-01-01
This is the second English edition of what has become one of the definitive works on superconductivity in German -- currently in its sixth edition. Comprehensive and easy to understand, this introductory text is written especially with the non-specialist in mind. The authors, both long-term experts in this field, present the fundamental considerations without the need for extensive mathematics, describing the various phenomena connected with the superconducting state, with liberal insertion of experimental facts and examples for modern applications. While all fields of superconducting phenomena are dealt with in detail, this new edition pays particular attention to the groundbreaking discovery of magnesium diboride and the current developments in this field. In addition, a new chapter provides an overview of the elements, alloys and compounds where superconductivity has been observed in experiments, together with their major characteristics. The chapter on technical applications has been considerably expanded...
Fundamentals of Fire Phenomena
DEFF Research Database (Denmark)
Quintiere, James
discipline. It covers thermo chemistry including mixtures and chemical reactions; Introduces combustion to the fire protection student; Discusses premixed flames and spontaneous ignition; Presents conservation laws for control volumes, including the effects of fire; Describes the theoretical bases...... analyses. Fire phenomena encompass everything about the scientific principles behind fire behaviour. Combining the principles of chemistry, physics, heat and mass transfer, and fluid dynamics necessary to understand the fundamentals of fire phenomena, this book integrates the subject into a clear...... for empirical aspects of the subject of fire; Analyses ignition of liquids and the importance of evaporation including heat and mass transfer; Features the stages of fire in compartments, and the role of scale modelling in fire. The book is written by Prof. James G. Quintiere from University of Maryland...
Automotive electronics design fundamentals
Zaman, Najamuz
2015-01-01
This book explains the topology behind automotive electronics architectures and examines how they can be profoundly augmented with embedded controllers. These controllers serve as the core building blocks of today’s vehicle electronics. Rather than simply teaching electrical basics, this unique resource focuses on the fundamental concepts of vehicle electronics architecture, and details the wide variety of Electronic Control Modules (ECMs) that enable the increasingly sophisticated "bells & whistles" of modern designs. A must-have for automotive design engineers, technicians working in automotive electronics repair centers and students taking automotive electronics courses, this guide bridges the gap between academic instruction and industry practice with clear, concise advice on how to design and optimize automotive electronics with embedded controllers.
Fundamentals of Fire Phenomena
DEFF Research Database (Denmark)
Quintiere, James
Understanding fire dynamics and combustion is essential in fire safety engineering and in fire science curricula. Engineers and students involved in fire protection, safety and investigation need to know and predict how fire behaves to be able to implement adequate safety measures and hazard...... analyses. Fire phenomena encompass everything about the scientific principles behind fire behaviour. Combining the principles of chemistry, physics, heat and mass transfer, and fluid dynamics necessary to understand the fundamentals of fire phenomena, this book integrates the subject into a clear...... discipline. It covers thermo chemistry including mixtures and chemical reactions; Introduces combustion to the fire protection student; Discusses premixed flames and spontaneous ignition; Presents conservation laws for control volumes, including the effects of fire; Describes the theoretical bases...
Noise elimination algorithm for modal analysis
Energy Technology Data Exchange (ETDEWEB)
Bao, X. X., E-mail: baoxingxian@upc.edu.cn [Department of Naval Architecture and Ocean Engineering, China University of Petroleum (East China), Qingdao 266580 (China); Li, C. L. [Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China); Xiong, C. B. [The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061 (China)
2015-07-27
Modal analysis is an ongoing interdisciplinary physical issue. Modal parameters estimation is applied to determine the dynamic characteristics of structures under vibration excitation. Modal analysis is more challenging for the measured vibration response signals are contaminated with noise. This study develops a mathematical algorithm of structured low rank approximation combined with the complex exponential method to estimate the modal parameters. Physical experiments using a steel cantilever beam with ten accelerometers mounted, excited by an impulse load, demonstrate that this method can significantly eliminate noise from measured signals and accurately identify the modal frequencies and damping ratios. This study provides a fundamental mechanism of noise elimination using structured low rank approximation in physical fields.
Effects of environmental noise on sleep.
Hume, Kenneth I; Brink, Mark; Basner, Mathias
2012-01-01
This paper summarizes the findings from the past 3 year's research on the effects of environmental noise on sleep and identifies key future research goals. The past 3 years have seen continued interest in both short term effects of noise on sleep (arousals, awakenings), as well as epidemiological studies focusing on long term health impacts of nocturnal noise exposure. This research corroborated findings that noise events induce arousals at relatively low exposure levels, and independent of the noise source (air, road, and rail traffic, neighbors, church bells) and the environment (home, laboratory, hospital). New epidemiological studies support already existing evidence that night-time noise is likely associated with cardiovascular disease and stroke in the elderly. These studies collectively also suggest that nocturnal noise exposure may be more relevant for the genesis of cardiovascular disease than daytime noise exposure. Relative to noise policy, new effect-oriented noise protection concepts, and rating methods based on limiting awakening reactions were introduced. The publications of WHO's ''Night Noise Guidelines for Europe'' and ''Burden of Disease from Environmental Noise'' both stress the importance of nocturnal noise exposure for health and well-being. However, studies demonstrating a causal pathway that directly link noise (at ecological levels) and disturbed sleep with cardiovascular disease and/or other long term health outcomes are still missing. These studies, as well as the quantification of the impact of emerging noise sources (e.g., high speed rail, wind turbines) have been identified as the most relevant issues that should be addressed in the field on the effects of noise on sleep in the near future.
Perception of speech in noise: neural correlates.
Song, Judy H; Skoe, Erika; Banai, Karen; Kraus, Nina
2011-09-01
The presence of irrelevant auditory information (other talkers, environmental noises) presents a major challenge to listening to speech. The fundamental frequency (F(0)) of the target speaker is thought to provide an important cue for the extraction of the speaker's voice from background noise, but little is known about the relationship between speech-in-noise (SIN) perceptual ability and neural encoding of the F(0). Motivated by recent findings that music and language experience enhance brainstem representation of sound, we examined the hypothesis that brainstem encoding of the F(0) is diminished to a greater degree by background noise in people with poorer perceptual abilities in noise. To this end, we measured speech-evoked auditory brainstem responses to /da/ in quiet and two multitalker babble conditions (two-talker and six-talker) in native English-speaking young adults who ranged in their ability to perceive and recall SIN. Listeners who were poorer performers on a standardized SIN measure demonstrated greater susceptibility to the degradative effects of noise on the neural encoding of the F(0). Particularly diminished was their phase-locked activity to the fundamental frequency in the portion of the syllable known to be most vulnerable to perceptual disruption (i.e., the formant transition period). Our findings suggest that the subcortical representation of the F(0) in noise contributes to the perception of speech in noisy conditions.
Directory of Open Access Journals (Sweden)
Alain Destexhe
2010-03-01
Full Text Available Cortical neurons in vivo may operate in high-conductance states, in which the major part of the neuron's input conductance is due to synaptic activity, sometimes several-fold larger than the resting conductance. We examine here the contribution of inhibition in such high-conductance states. At the level of the absolute conductance values, several studies have shown that cortical neurons in vivo are characterized by strong inhibitory conductances. However, conductances are balanced and spiking activity is mostly determined by fluctuations, but not much is known about excitatory and inhibitory contributions to these fluctuations. Models and dynamic-clamp experiments show that, during high-conductance states, spikes are mainly determined by fluctuations of inhibition, or by inhibitory noise. This stands in contrast to low-conductance states, in which excitatory conductances determine spiking activity. To determine these contributions from experimental data, maximum likelihood methods can be designed and applied to intracellular recordings in vivo. Such methods indicate that action potentials are indeed mostly correlated with inhibitory fluctuations in awake animals. These results argue for a determinant role for inhibitory fluctuations in evoking spikes, and do not support feed-forward modes of processing, for which opposite patterns are predicted.
Energy Technology Data Exchange (ETDEWEB)
Vernieri, Julieta; Arnera, Patricia [Universidad Nacional de La Plata (UNLP), Buenos Aires (Argentina). Facultad de Ingenieria. Inst. de Investigaciones Tecnologicas para Redes y Equipos Electricos (IITREE-LAT)]. E-mail: jvernier@volta.ing.unlp.edu.ar; Massei, Cristina [Ente Nacional Regulador de la Electricidad (ENRE), Buenos Aires (Argentina)
2001-07-01
While the effects of short term in the human health due to exposure to electric and magnetic fields at the fundamental frequency are well-known, discussions with respect to the existence of effects of long term, specially cancer, persists at world-wide level. In order to evaluate the associated risks, interdisciplinary programs analyze the results of epidemic researches and also laboratory researches. In the present document, some of the last reviews have been showed, as well as it also is summarized the regulations for the limit values of expositure. It also makes reference to the special case of an italian standard as well.
Energy Technology Data Exchange (ETDEWEB)
NONE
2010-06-15
Occupational noise is a frequently encountered on-the-job health hazard. This guide presented the responsibilities and regulatory requirements related to business activities where noise above 80 decibels is present. The guide provided a definition of noise and discussed noise hazards, types of noise, and on-the-job noise exposure. A risk assessment to noise in the work environment was also discussed. A guide to a hearing conservation program was also included. The main purpose of a hearing conservation program is the prevention of noise induced hearing loss for employees exposed to occupational noise. The components of such a program were outlined, with particular reference to noise monitoring; noise exposure control; worker education and training; hearing (audiometric) testing; and annual program review and record keeping. It was concluded that in terms of record keeping, it can be very helpful to file noise exposure assessments, particularly personal exposure measurements, with hearing test records to facilitate for future reference. refs., appendices.
... ENTCareers Marketplace Find an ENT Doctor Near You Noise and Hearing Protection Noise and Hearing Protection Patient ... it is. How can I tell if a noise is dangerous? People differ in their sensitivity to ...
Directory of Open Access Journals (Sweden)
Mariola Sliwinska-Kowalska
2012-01-01
Full Text Available Noise-induced hearing loss (NIHL still remains a problem in developed countries, despite reduced occupational noise exposure, strict standards for hearing protection and extensive public health awareness campaigns. Therefore NIHL continues to be the focus of noise research activities. This paper summarizes progress achieved recently in our knowledge of NIHL. It includes papers published between the years 2008-2011 (in English, which were identified by a literature search of accessible medical and other relevant databases. A substantial part of this research has been concerned with the risk of NIHL in the entertainment sector, particularly in professional, orchestral musicians. There are also constant concerns regarding noise exposure and hearing risk in "hard to control" occupations, such as farming and construction work. Although occupational noise has decreased since the early 1980s, the number of young people subject to social noise exposure has tripled. If the exposure limits from the Noise at Work Regulations are applied, discotheque music, rock concerts, as well as music from personal music players are associated with the risk of hearing loss in teenagers and young adults. Several recent research studies have increased the understanding of the pathomechanisms of acoustic trauma, the genetics of NIHL, as well as possible dietary and pharmacologic otoprotection in acoustic trauma. The results of these studies are very promising and offer grounds to expect that targeted therapies might help prevent the loss of sensory hair cells and protect the hearing of noise-exposed individuals. These studies emphasize the need to launch an improved noise exposure policy for hearing protection along with developing more efficient norms of NIHL risk assessment.
Fundamentals of ergonomic exoskeleton robots
Schiele, A.
2008-01-01
This thesis is the first to provide the fundamentals of ergonomic exoskeleton design. The fundamental theory as well as technology necessary to analyze and develop ergonomic wearable robots interacting with humans is established and validated by experiments and prototypes. The fundamentals are (1) a
Fundamentals of ergonomic exoskeleton robots
Schiele, A.
2008-01-01
This thesis is the first to provide the fundamentals of ergonomic exoskeleton design. The fundamental theory as well as technology necessary to analyze and develop ergonomic wearable robots interacting with humans is established and validated by experiments and prototypes. The fundamentals are (1) a
Noise, errors and information in quantum amplification
D'Ariano, G M; Maccone, L
1997-01-01
We analyze and compare the characterization of a quantum device in terms of noise, transmitted bit-error-rate (BER) and mutual information, showing how the noise description is meaningful only for Gaussian channels. After reviewing the description of a quantum communication channel, we study the insertion of an amplifier. We focus attention on the case of direct detection, where the linear amplifier has a 3 decibels noise figure, which is usually considered an unsurpassable limit, referred to as the standard quantum limit (SQL). Both noise and BER could be reduced using an ideal amplifier, which is feasible in principle. However, just a reduction of noise beyond the SQL does not generally correspond to an improvement of the BER or of the mutual information. This is the case of a laser amplifier, where saturation can greatly reduce the noise figure, although there is no corresponding improvement of the BER. Such mechanism is illustrated on the basis of Monte Carlo simulations.
Correlated L\\'evy noise in linear dynamical systems
Srokowski, Tomasz
2010-01-01
Linear dynamical systems, driven by a non-white noise which has the Levy distribution, are analysed. Noise is modelled by a specific stochastic process which is defined by the Langevin equation with a linear force and the Levy distributed symmetric white noise. Correlation properties of the process are discussed. The Fokker-Planck equation driven by that noise is solved. Distributions have the Levy shape and their width, for a given time, is smaller than for processes in the white noise limit...
Fundamentals of klystron testing
Energy Technology Data Exchange (ETDEWEB)
Caldwell, J.W. Jr.
1978-08-01
Fundamentals of klystron testing is a text primarily intended for the indoctrination of new klystron group test stand operators. It should significantly reduce the familiarization time of a new operator, making him an asset to the group sooner than has been experienced in the past. The new employee must appreciate the mission of SLAC before he can rightfully be expected to make a meaningful contribution to the group's effort. Thus, the introductory section acquaints the reader with basic concepts of accelerators in general, then briefly describes major physical aspects of the Stanford Linear Accelerator. Only then is his attention directed to the klystron, with its auxiliary systems, and the rudiments of klystron tube performance checks. It is presumed that the reader is acquainted with basic principles of electronics and scientific notation. However, to preserve the integrity of an indoctrination guide, tedious technical discussions and mathematical analysis have been studiously avoided. It is hoped that the new operator will continue to use the text for reference long after his indoctrination period is completed. Even the more experienced operator should find that particular sections will refresh his understanding of basic principles of klystron testing.
Petitjean, Patrick; Wang, F. Y.; Wu, X. F.; Wei, J. J.
2016-12-01
Gamma-ray bursts (GRBs) are short and intense flashes at the cosmological distances, which are the most luminous explosions in the Universe. The high luminosities of GRBs make them detectable out to the edge of the visible universe. So, they are unique tools to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal evolution of the Universe. First, they can be used to constrain the history of cosmic acceleration and the evolution of dark energy in a redshift range hardly achievable by other cosmological probes. Second, long GRBs are believed to be formed by collapse of massive stars. So they can be used to derive the high-redshift star formation rate, which can not be probed by current observations. Moreover, the use of GRBs as cosmological tools could unveil the reionization history and metal evolution of the Universe, the intergalactic medium (IGM) properties and the nature of first stars in the early universe. But beyond that, the GRB high-energy photons can be applied to constrain Lorentz invariance violation (LIV) and to test Einstein's Equivalence Principle (EEP). In this paper, we review the progress on the GRB cosmology and fundamental physics probed by GRBs.
Revisiting energy efficiency fundamentals
Energy Technology Data Exchange (ETDEWEB)
Perez-Lombard, L.; Velazquez, D. [Grupo de Termotecnia, Escuela Superior de Ingenieros, Universidad de Sevilla, Camino de los Descubrimientos s/n, 41092 Seville (Spain); Ortiz, J. [Building Research Establishment (BRE), Garston, Watford, WD25 9XX (United Kingdom)
2013-05-15
Energy efficiency is a central target for energy policy and a keystone to mitigate climate change and to achieve a sustainable development. Although great efforts have been carried out during the last four decades to investigate the issue, focusing into measuring energy efficiency, understanding its trends and impacts on energy consumption and to design effective energy efficiency policies, many energy efficiency-related concepts, some methodological problems for the construction of energy efficiency indicators (EEI) and even some of the energy efficiency potential gains are often ignored or misunderstood, causing no little confusion and controversy not only for laymen but even for specialists. This paper aims to revisit, analyse and discuss some efficiency fundamental topics that could improve understanding and critical judgement of efficiency stakeholders and that could help in avoiding unfounded judgements and misleading statements. Firstly, we address the problem of measuring energy efficiency both in qualitative and quantitative terms. Secondly, main methodological problems standing in the way of the construction of EEI are discussed, and a sequence of actions is proposed to tackle them in an ordered fashion. Finally, two key topics are discussed in detail: the links between energy efficiency and energy savings, and the border between energy efficiency improvement and renewable sources promotion.
Tenfold reduction of Brownian noise in optical interferometry
Cole, Garrett D; Martin, Michael J; Ye, Jun; Aspelmeyer, Markus
2013-01-01
Thermally induced fluctuations impose a fundamental limit on precision measurement. In optical interferometry, the current bounds of stability and sensitivity are dictated by the excess mechanical damping of the high-reflectivity coatings that comprise the cavity end mirrors. Over the preceding decade, the mechanical loss of these amorphous multilayer reflectors has at best been reduced by a factor of two. Here we demonstrate a new paradigm in optical coating technology based on direct-bonded monocrystalline multilayers, which exhibit both intrinsically low mechanical loss and high optical quality. Employing these "crystalline coatings" as end mirrors in a Fabry-P\\'erot cavity, we obtain a finesse of 150,000. More importantly, at room temperature, we observe a thermally-limited noise floor consistent with a tenfold reduction in mechanical damping when compared with the best dielectric multilayers. These results pave the way for the next generation of ultra-sensitive interferometers, as well as for new levels ...
Fundamental Physics and Precision Measurements
Hänsch, T. W.
2006-11-01
"Very high precision physics has always appealed to me. The steady improvement in technologies that afford higher and higher precision has been a regular source of excitement and challenge during my career. In science, as in most things, whenever one looks at something more closely, new aspects almost always come into play …" With these word from the book "How the Laser happened", Charles H. Townes expresses a passion for precision that is now shared by many scientists. Masers and lasers have become indispensible tools for precision measurements. During the past few years, the advent of femtosecond laser frequency comb synthesizers has revolutionized the art of directly comparing optical and microwave frequencies. Inspired by the needs of precision laser spectroscopy of the simple hydrogen atom, such frequency combs are now enabling ultra-precise spectroscopy over wide spectral ranges. Recent laboratory experiments are already setting stringent limits for possible slow variations of fundamental constants. Laser frequency combs also provide the long missing clockwork for optical atomic clocks that may ultimately reach a precision of parts in 1018 and beyond. Such tools will open intriguing new opportunities for fundamental experiments including new tests of special and general relativity. In the future, frequency comb techniques may be extended into the extreme ultraviolet and soft xray regime, opening a vast new spectral territory to precision measurements. Frequency combs have also become a key tool for the emerging new field of attosecond science, since they can control the electric field of ultrashort laser pulses on an unprecedented time scale. The biggest surprise in these endeavours would be if we found no surprise.
Fundamental enabling issues in nanotechnology :
Energy Technology Data Exchange (ETDEWEB)
Floro, Jerrold Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Foiles, Stephen Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hearne, Sean Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hoyt, Jeffrey John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Seel, Steven Craig [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Webb III, Edmund Blackburn [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Morales, Alfredo Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zimmerman, Jonathan A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2007-10-01
To effectively integrate nanotechnology into functional devices, fundamental aspects of material behavior at the nanometer scale must be understood. Stresses generated during thin film growth strongly influence component lifetime and performance; stress has also been proposed as a mechanism for stabilizing supported nanoscale structures. Yet the intrinsic connections between the evolving morphology of supported nanostructures and stress generation are still a matter of debate. This report presents results from a combined experiment and modeling approach to study stress evolution during thin film growth. Fully atomistic simulations are presented predicting stress generation mechanisms and magnitudes during all growth stages, from island nucleation to coalescence and film thickening. Simulations are validated by electrodeposition growth experiments, which establish the dependence of microstructure and growth stresses on process conditions and deposition geometry. Sandia is one of the few facilities with the resources to combine experiments and modeling/theory in this close a fashion. Experiments predicted an ongoing coalescence process that generates signficant tensile stress. Data from deposition experiments also supports the existence of a kinetically limited compressive stress generation mechanism. Atomistic simulations explored island coalescence and deposition onto surfaces intersected by grain boundary structures to permit investigation of stress evolution during later growth stages, e.g. continual island coalescence and adatom incorporation into grain boundaries. The predictive capabilities of simulation permit direct determination of fundamental processes active in stress generation at the nanometer scale while connecting those processes, via new theory, to continuum models for much larger island and film structures. Our combined experiment and simulation results reveal the necessary materials science to tailor stress, and therefore performance, in
Directory of Open Access Journals (Sweden)
Daniel Shepherd
2010-10-01
Full Text Available The relationship between environmental noise and health is poorly understood but of fundamental importance to public health. This study estimated the relationship between noise sensitivity, noise annoyance and health-related quality of life in a sample of adults residing close to the Auckland International Airport, New Zealand. A small sample (n = 105 completed surveys measuring noise sensitivity, noise annoyance, and quality of life. Noise sensitivity was associated with health-related quality of life; annoyance and sleep disturbance mediated the effects of noise sensitivity on health.
Spaces of fundamental and generalized functions
Gel'Fand, I M
2013-01-01
Spaces of Fundamental and Generalized Functions, Volume 2, analyzes the general theory of linear topological spaces. The basis of the theory of generalized functions is the theory of the so-called countably normed spaces (with compatible norms), their unions (inductive limits), and also of the spaces conjugate to the countably normed ones or their unions. This set of spaces is sufficiently broad on the one hand, and sufficiently convenient for the analyst on the other. The book opens with a chapter that discusses the theory of these spaces. This is followed by separate chapters on fundamental
Plasmonics fundamentals and applications
Maier, Stefan Alexander
2007-01-01
Considered a major field of photonics, plasmonics offers the potential to confine and guide light below the diffraction limit and promises a new generation of highly miniaturized photonic devices. This book combines a comprehensive introduction with an extensive overview of the current state of the art. Coverage includes plasmon waveguides, cavities for field-enhancement, nonlinear processes and the emerging field of active plasmonics studying interactions of surface plasmons with active media.
Stochastic resonance with colored noise for neural signal detection.
Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek
2014-01-01
We analyze signal detection with nonlinear test statistics in the presence of colored noise. In the limits of small signal and weak noise correlation, the optimal test statistic and its performance are derived under general conditions, especially concerning the type of noise. We also analyze, for a threshold nonlinearity-a key component of a neural model, the conditions for noise-enhanced performance, establishing that colored noise is superior to white noise for detection. For a parallel array of nonlinear elements, approximating neurons, we demonstrate even broader conditions allowing noise-enhanced detection, via a form of suprathreshold stochastic resonance.
Stochastic resonance with colored noise for neural signal detection.
Directory of Open Access Journals (Sweden)
Fabing Duan
Full Text Available We analyze signal detection with nonlinear test statistics in the presence of colored noise. In the limits of small signal and weak noise correlation, the optimal test statistic and its performance are derived under general conditions, especially concerning the type of noise. We also analyze, for a threshold nonlinearity-a key component of a neural model, the conditions for noise-enhanced performance, establishing that colored noise is superior to white noise for detection. For a parallel array of nonlinear elements, approximating neurons, we demonstrate even broader conditions allowing noise-enhanced detection, via a form of suprathreshold stochastic resonance.
Spin-noise correlations and spin-noise exchange driven by low-field spin-exchange collisions
Dellis, A. T.; Loulakis, M.; Kominis, I. K.
2013-01-01
The physics of spin exchange collisions have fueled several discoveries in fundamental physics and numerous applications in medical imaging and nuclear magnetic resonance. We here report on the experimental observation and theoretical justification of spin-noise exchange, the transfer of spin-noise from one atomic species to another. The signature of spin-noise exchange is an increase of the total spin-noise power at low magnetic fields, on the order of 1 mG, where the two-species spin-noise ...
Effects of environmental noise on sleep
Directory of Open Access Journals (Sweden)
Kenneth I Hume
2012-01-01
Full Text Available This paper summarizes the findings from the past 3 year′s research on the effects of environmental noise on sleep and identifies key future research goals. The past 3 years have seen continued interest in both short term effects of noise on sleep (arousals, awakenings, as well as epidemiological studies focusing on long term health impacts of nocturnal noise exposure. This research corroborated findings that noise events induce arousals at relatively low exposure levels, and independent of the noise source (air, road, and rail traffic, neighbors, church bells and the environment (home, laboratory, hospital. New epidemiological studies support already existing evidence that night-time noise is likely associated with cardiovascular disease and stroke in the elderly. These studies collectively also suggest that nocturnal noise exposure may be more relevant for the genesis of cardiovascular disease than daytime noise exposure. Relative to noise policy, new effect-oriented noise protection concepts, and rating methods based on limiting awakening reactions were introduced. The publications of WHO′s ′′Night Noise Guidelines for Europe′′ and ′′Burden of Disease from Environmental Noise′′ both stress the importance of nocturnal noise exposure for health and well-being. However, studies demonstrating a causal pathway that directly link noise (at ecological levels and disturbed sleep with cardiovascular disease and/or other long term health outcomes are still missing. These studies, as well as the quantification of the impact of emerging noise sources (e.g., high speed rail, wind turbines have been identified as the most relevant issues that should be addressed in the field on the effects of noise on sleep in the near future.
Barton, Sinead J.; Kerr, Laura T.; Domijan, Katarina; Hennelly, Bryan M.
2016-04-01
Raman micro-spectroscopy is an optoelectronic technique that can be used to evaluate the chemical composition of biological samples and has been shown to be a powerful diagnostic tool for the investigation of various cancer related diseases including bladder, breast, and cervical cancer. Raman scattering is an inherently weak process with approximately 1 in 107 photons undergoing scattering and for this reason, noise from the recording system can have a significant impact on the quality of the signal, and its suitability for diagnostic classification. The main sources of noise in the recorded signal are shot noise, CCD dark current, and CCD readout noise. Shot noise results from the low signal photon count while dark current results from thermally generated electrons in the semiconductor pixels. Both of these noise sources are time dependent; readout noise is time independent but is inherent in each individual recording and results in the fundamental limit of measurement, arising from the internal electronics of the camera. In this paper, each of the aforementioned noise sources are analysed in isolation, and used to experimentally validate a mathematical model. This model is then used to simulate spectra that might be acquired under various experimental conditions including the use of different cameras, different source wavelength, and power etc. Simulated noisy datasets of T24 and RT112 cell line spectra are generated based on true cell Raman spectrum irradiance values (recorded using very long exposure times) and the addition of simulated noise. These datasets are then input to multivariate classification using Principal Components Analysis and Linear Discriminant Analysis. This method enables an investigation into the effect of noise on the sensitivity and specificity of Raman based classification under various experimental conditions and using different equipment.
Chicago transit authority train noise exposure.
Phan, Linh T; Jones, Rachael M
2017-06-01
To characterize noise exposure of riders on Chicago Transit Authority (CTA) trains, we measured noise levels twice on each segment of 7 of the 8 CTA train lines, which are named after colors, yielding 48 time-series measurements. We found the Blue Line has the highest noise levels compared to other train lines, with mean 76.9 dBA; and that the maximum noise level, 88.9 dBA occurred in the tunnel between the Chicago and Grand stations. Train segments involving travel through a tunnel had significantly higher noise levels than segments with travel on elevated and ground level tracks. While 8-hr doses inside the passenger cars were not estimated to exceed occupational exposure limits, train operators ride in a separate cab with operational windows and may therefore have higher noise exposures than riders. Despite the low risk of hearing loss for riders on CTA trains, in part because transit noise accounts for a small part of total daily noise exposure, 1-min average noise levels exceeded 85 dBA at times. This confirms anecdotal observations of discomfort due to noise levels, and indicates a need for noise management, particularly in tunnels.
Directory of Open Access Journals (Sweden)
F. TopsÃƒÂ¸e
2001-09-01
Full Text Available Abstract: In its modern formulation, the Maximum Entropy Principle was promoted by E.T. Jaynes, starting in the mid-fifties. The principle dictates that one should look for a distribution, consistent with available information, which maximizes the entropy. However, this principle focuses only on distributions and it appears advantageous to bring information theoretical thinking more prominently into play by also focusing on the "observer" and on coding. This view was brought forward by the second named author in the late seventies and is the view we will follow-up on here. It leads to the consideration of a certain game, the Code Length Game and, via standard game theoretical thinking, to a principle of Game Theoretical Equilibrium. This principle is more basic than the Maximum Entropy Principle in the sense that the search for one type of optimal strategies in the Code Length Game translates directly into the search for distributions with maximum entropy. In the present paper we offer a self-contained and comprehensive treatment of fundamentals of both principles mentioned, based on a study of the Code Length Game. Though new concepts and results are presented, the reading should be instructional and accessible to a rather wide audience, at least if certain mathematical details are left aside at a rst reading. The most frequently studied instance of entropy maximization pertains to the Mean Energy Model which involves a moment constraint related to a given function, here taken to represent "energy". This type of application is very well known from the literature with hundreds of applications pertaining to several different elds and will also here serve as important illustration of the theory. But our approach reaches further, especially regarding the study of continuity properties of the entropy function, and this leads to new results which allow a discussion of models with so-called entropy loss. These results have tempted us to speculate over
Fundamentals of Space Medicine
Clément, Gilles
2005-03-01
A total of more than 240 human space flights have been completed to date, involving about 450 astronauts from various countries, for a combined total presence in space of more than 70 years. The seventh long-duration expedition crew is currently in residence aboard the International Space Station, continuing a permanent presence in space that began in October 2000. During that time, investigations have been conducted on both humans and animal models to study the bone demineralization and muscle deconditioning, space motion sickness, the causes and possible treatment of postflight orthostatic intolerance, the changes in immune function, crew and crew-ground interactions, and the medical issues of living in a space environment, such as the effects of radiation or the risk of developing kidney stones. Some results of these investigations have led to fundamental discoveries about the adaptation of the human body to the space environment. Gilles Clément has been active in this research. This readable text presents the findings from the life science experiments conducted during and after space missions. Topics discussed in this book include: adaptation of sensory-motor, cardio-vascular, bone, and muscle systems to the microgravity of spaceflight; psychological and sociological issues of living in a confined, isolated, and stressful environment; operational space medicine, such as crew selection, training and in-flight health monitoring, countermeasures and support; results of space biology experiments on individual cells, plants, and animal models; and the impact of long-duration missions such as the human mission to Mars. The author also provides a detailed description of how to fly a space experiment, based on his own experience with research projects conducted onboard Salyut-7, Mir, Spacelab, and the Space Shuttle. Now is the time to look at the future of human spaceflight and what comes next. The future human exploration of Mars captures the imagination of both the
Noise Considerations in Resistance Bridges
DEFF Research Database (Denmark)
Diamond, Joseph M.
1963-01-01
A signal-to-noise analysis is made of the Wheatstone bridge, where the unknown and standard resistors may be at different temperatures, a situation which occurs in resistance thermometry. The limiting condition is assumed to be dissipation in the unknown resistor. It is shown that the ratio arms ...
Improtance of fundamental study in hydrometallurgy
Majima, Hiroshi
1995-02-01
Recent developments in modeling and optimization studies using computer technology have had a remarkable effect on all areas of extractive metallurgy. However, a lack of fundamental data regarding, for instance, activities, diffusion coefficients, limiting current densities, etc. obstructs the reliable use of this method. In studying hydrometallurgy, I recognized the importance of fundamental analysis and continued such works throughout my university life. For example, activities of water and solutes of the solution systems H2SO4-Mx(SO4)y-H2O and HCl-MClx-H2O were determined, and the results were employed to analyze the dissolution mechanism of metal oxides as well as metal sulfides in those solutions. In this article, fundamental studies mainly made in my laboratory to understand hydrometallurgical phenomena will be discussed.
Eversman, Walter
The differences in the radiated acoustic fields of ducted and unducted propellers of the same thrust operating under similar conditions are investigated. An FEM model is created for the generation, propagation, and radiation of steady, rotor alone noise and exit guide vane interaction noise of a ducted fan. For a specified number of blades, angular mode harmonic, and rotor angular velocity, the acoustic field is described in a cylindrical coordinate system reduced to only the axial and radial directions. It is found that, contrary to the usual understanding of the Tyler and Sofrin (1962) result, supersonic tip speed rotor noise can be cut off if the tip Mach number is only slightly in excess of unity and if the number of blades is relatively small. If there are many blades, the fundamental angular mode number is large, and the Tyler and Sofrin result for thin annuli becomes more relevant. Shrouding of subsonic tip speed propellers is a very effective means of controlling rotor alone noise.
Quantum speed limits in open system dynamics.
del Campo, A; Egusquiza, I L; Plenio, M B; Huelga, S F
2013-02-01
Bounds to the speed of evolution of a quantum system are of fundamental interest in quantum metrology, quantum chemical dynamics, and quantum computation. We derive a time-energy uncertainty relation for open quantum systems undergoing a general, completely positive, and trace preserving evolution which provides a bound to the quantum speed limit. When the evolution is of the Lindblad form, the bound is analogous to the Mandelstam-Tamm relation which applies in the unitary case, with the role of the Hamiltonian being played by the adjoint of the generator of the dynamical semigroup. The utility of the new bound is exemplified in different scenarios, ranging from the estimation of the passage time to the determination of precision limits for quantum metrology in the presence of dephasing noise.
Some new viewpoints in reactor noise analysis
Institute of Scientific and Technical Information of China (English)
罗征培; 李富; 等
1996-01-01
It is propsed that the linearity criterion and order criterion via frequency spectrum features without any limitation of the model's phase can be used in reactor noise analysis.The time constant,natural frequency as well as the recovered transfer function of reactors can bhe obtained via the analyzable model based on reactor noise.
Quantum noise-induced chaotic oscillations
Bag, Bidhan Chandra; Ray, Deb Shankar
1999-01-01
We examine the weak quantum noise limit of Wigner equation for phase space distribution functions. It has been shown that the leading order quantum noise described in terms of an auxiliary Hamiltonian manifests itself as an additional fluctuational degree of freedom which may induce chaotic and regular oscillations in a nonlinear oscillator.
Quantum noise-induced chaotic oscillations
Bag, B C; Bag, Bidhan Chandra; Ray, Deb Shankar
1999-01-01
We examine the weak quantum noise limit of Wigner equation for phase space distribution functions. It has been shown that the leading order quantum noise described in terms of an auxilliary Hamiltonian manifests itself as an additional fluctuational degree of freedom which may induce chaotic and regular oscillations in a nonlinear oscillator.
Charting environmental pollution. [by noise measurements
Halpert, E.; Bizo, F.; Karacsonyi, Z.
1974-01-01
It is found that areas affected by different noxious agents are within the limits traced for high noise level areas; consequently, it is suggested that high noise pressure levels should be used as the primary indication of environmental pollution. A complex methodology is reported for charting environmental pollution due to physical, chemical and biological noxious agents on the scale of an industrial district.
Constraining fundamental constants of physics with quasar absorption line systems
Petitjean, Patrick; Chand, Hum; Ivanchik, Alexander; Noterdaeme, Pasquier; Gupta, Neeraj
2009-01-01
We summarize the attempts by our group and others to derive constraints on variations of fundamental constants over cosmic time using quasar absorption lines. Most upper limits reside in the range 0.5-1.5x10-5 at the 3sigma level over a redshift range of approximately 0.5-2.5 for the fine-structure constant, alpha, the proton-to-electron mass ratio, mu, and a combination of the proton gyromagnetic factor and the two previous constants, gp(alpha^2/mu)^nu, for only one claimed variation of alpha. It is therefore very important to perform new measurements to improve the sensitivity of the numerous methods to at least <0.1x10-5 which should be possible in the next few years. Future instrumentations on ELTs in the optical and/or ALMA, EVLA and SKA pathfinders in the radio will undoutedly boost this field by allowing to reach much better signal-to-noise ratios at higher spectral resolution and to perform measurements on molecules in the ISM of high redshift galaxies.
Institute of Scientific and Technical Information of China (English)
刘玲娣
2007-01-01
Someone is singing next door,but you feel unhappy because her singing is just making a noise.We know that too much noise makes people feel terrible. Scientists are still trying to find out more about noise,but already it is known that a noise of over 85 decibels can make some people tired and anxious.
Active Noise Control for Dishwasher noise
Lee, Nokhaeng; Park, Youngjin
2016-09-01
The dishwasher is a useful home appliance and continually used for automatically washing dishes. It's commonly placed in the kitchen with built-in style for practicality and better use of space. In this environment, people are easily exposed to dishwasher noise, so it is an important issue for the consumers, especially for the people living in open and narrow space. Recently, the sound power levels of the noise are about 40 - 50 dBA. It could be achieved by removal of noise sources and passive means of insulating acoustical path. For more reduction, such a quiet mode with the lower speed of cycle has been introduced, but this deteriorates the washing capacity. Under this background, we propose active noise control for dishwasher noise. It is observed that the noise is propagating mainly from the lower part of the front side. Control speakers are placed in the part for the collocation. Observation part of estimating sound field distribution and control part of generating the anti-noise are designed for active noise control. Simulation result shows proposed active noise control scheme could have a potential application for dishwasher noise reduction.
Energy Technology Data Exchange (ETDEWEB)
Sandborg, Michael; Carlsson, G.A. (Linkoeping Univ. (Sweden). Dept. of Radiation Physics)
1992-06-01
A lower limit to patient irradiation in diagnostic radiology is set by the fundamental stochastics of the energy imparted to the image receptor (quantum noise). Image quality is investigated here and expressed in terms of the signal-to-noise ratio due to quantum noise. The Monte Carlo method is used to calculate signal-to-noise ratios (SNR{sub {Delta}S}) and detective quantum efficiencies (DQE{sub {Delta}S}) in imaging thin contrasting details of air, fat, bone and iodine within a water phantom using x-ray spectra (40-140 kV) and detectors of CsI, BaFCl and Gd{sub 2}O{sub 2}S. The atomic composition of the contrasting detail influences considerably the values of SNR{sub {Delta}S} due to the different modulations of the energy spectra of primary photons passing beside and through the contrasting detail. (author).
Communication technology update and fundamentals
Grant, August E
2010-01-01
New communication technologies are being introduced at an astonishing rate. Making sense of these technologies is increasingly difficult. Communication Technology Update and Fundamentals is the single best source for the latest developments, trends, and issues in communication technology. Featuring the fundamental framework along with the history and background of communication technologies, Communication Technology Update and Fundamentals, 12th edition helps you stay ahead of these ever-changing and emerging technologies.As always, every chapter ha
Low Frequency Noise Measurement and Analysis of Capacitive Micro-Accelerometers: Temperature Effect
Mohd-Yasin, Faisal; Nagel, David J.; Ong, D. S.; Korman, Can E.; Chuah, H. T.
2008-06-01
A noise measurements of micro-accelerometers were performed using a special measurement system. A common spectral behavior of noise is found, with 1/ f noise dominating at low frequencies and white thermal noise being the limiting factor at higher frequencies. A temperature dependent and an acceleration dependant of the noise are found in the accelerometers, in agreement and contract of the theories, respectively.
Noise propagation characteristics of underground equipment in coal mines
Institute of Scientific and Technical Information of China (English)
CHENG Gen-yin; WEI Zhi-yong; XU Ming; ZHU Yan-yan
2012-01-01
On the basis of the survey of underground noise in Jinggezhuang and Donghuantuo mines,Kailuan Group,noise radiation intensity,noise propagation properties and noise frequency-spectrum characteristics of underground equipment were studied at different work conditions.The result indicates that the noise source intensity surpasses the noise limit requirement of 85 dBA completely.Nearly 70％ noise sources exceed the noise limit of 90 dBA,and some are over 100 dBA.Noise attenuation in semi-free field environment on the ground is significantly different from underground far-field environment of noise source in coal mines.Noise of these regions,where staffs are long and highly concentrated,exceeds 85 dBA,the basic noise limit.The noise frequency-spectrum presents the wideband characteristics.Especially in the main frequency of the language communication 500,1 000 and 2 000 Hz,the octave band of noise performs obviously.
Institute of Scientific and Technical Information of China (English)
毛虎; 吴德伟; 卢虎
2015-01-01
Aim at the problem of low efficiency of band-limited Gaussian noise jamming, using code tracking error and ephemeris bit error rate of GPS receiver as the jamming effect evaluation index, on the basis of analysis characteristics of GPS C/A code, P( Y) code and M code signal power spectral density, to carry on the theoretical derivation about jamming bandwidth influence code tracking and ephemeris demodulation process, the existence of optimal jamming bandwidth is judged qualitative. The quantitative simulation results show that when the JSR is small, the bit error rate influence should be fully considered, the jamming bandwidth which causes the biggest code tracking er-ror should reduce a little as the best jamming bandwidth for C/A code signal, the best jamming bandwidth should choose the jamming band-width which causes the biggest code tracking error for the P( Y) code and M code signal.%针对带限高斯噪声干扰效率低下的问题，以GPS接收机码跟踪误差和星历误码率作为干扰效果评估准则，在分析GPS C/A码、P( Y)码和M码信号功率谱特点的基础上，通过对干扰带宽影响码跟踪和星历解调过程进行理论推导，定性的判断出最佳干扰带宽的存在。定量的仿真分析结果表明：对于C/A码信号，当干信比较小时，要充分考虑到误码率的影响，将造成码跟踪误差最大的干扰带宽减小一些，作为其最佳干扰带宽；而对于P( Y)码和M码信号，应选择造成码跟踪误差最大的干扰带宽，作为其最佳干扰带宽。
Fundamental Scaling Laws in Nanophotonics
Liu, Ke; Sun, Shuai; Majumdar, Arka; Sorger, Volker J.
2016-11-01
The success of information technology has clearly demonstrated that miniaturization often leads to unprecedented performance, and unanticipated applications. This hypothesis of “smaller-is-better” has motivated optical engineers to build various nanophotonic devices, although an understanding leading to fundamental scaling behavior for this new class of devices is missing. Here we analyze scaling laws for optoelectronic devices operating at micro and nanometer length-scale. We show that optoelectronic device performance scales non-monotonically with device length due to the various device tradeoffs, and analyze how both optical and electrical constrains influence device power consumption and operating speed. Specifically, we investigate the direct influence of scaling on the performance of four classes of photonic devices, namely laser sources, electro-optic modulators, photodetectors, and all-optical switches based on three types of optical resonators; microring, Fabry-Perot cavity, and plasmonic metal nanoparticle. Results show that while microrings and Fabry-Perot cavities can outperform plasmonic cavities at larger length-scales, they stop working when the device length drops below 100 nanometers, due to insufficient functionality such as feedback (laser), index-modulation (modulator), absorption (detector) or field density (optical switch). Our results provide a detailed understanding of the limits of nanophotonics, towards establishing an opto-electronics roadmap, akin to the International Technology Roadmap for Semiconductors.
Fundamental Scaling Laws in Nanophotonics.
Liu, Ke; Sun, Shuai; Majumdar, Arka; Sorger, Volker J
2016-11-21
The success of information technology has clearly demonstrated that miniaturization often leads to unprecedented performance, and unanticipated applications. This hypothesis of "smaller-is-better" has motivated optical engineers to build various nanophotonic devices, although an understanding leading to fundamental scaling behavior for this new class of devices is missing. Here we analyze scaling laws for optoelectronic devices operating at micro and nanometer length-scale. We show that optoelectronic device performance scales non-monotonically with device length due to the various device tradeoffs, and analyze how both optical and electrical constrains influence device power consumption and operating speed. Specifically, we investigate the direct influence of scaling on the performance of four classes of photonic devices, namely laser sources, electro-optic modulators, photodetectors, and all-optical switches based on three types of optical resonators; microring, Fabry-Perot cavity, and plasmonic metal nanoparticle. Results show that while microrings and Fabry-Perot cavities can outperform plasmonic cavities at larger length-scales, they stop working when the device length drops below 100 nanometers, due to insufficient functionality such as feedback (laser), index-modulation (modulator), absorption (detector) or field density (optical switch). Our results provide a detailed understanding of the limits of nanophotonics, towards establishing an opto-electronics roadmap, akin to the International Technology Roadmap for Semiconductors.
Information physics fundamentals of nanophotonics.
Naruse, Makoto; Tate, Naoya; Aono, Masashi; Ohtsu, Motoichi
2013-05-01
Nanophotonics has been extensively studied with the aim of unveiling and exploiting light-matter interactions that occur at a scale below the diffraction limit of light, and recent progress made in experimental technologies--both in nanomaterial fabrication and characterization--is driving further advancements in the field. From the viewpoint of information, on the other hand, novel architectures, design and analysis principles, and even novel computing paradigms should be considered so that we can fully benefit from the potential of nanophotonics. This paper examines the information physics aspects of nanophotonics. More specifically, we present some fundamental and emergent information properties that stem from optical excitation transfer mediated by optical near-field interactions and the hierarchical properties inherent in optical near-fields. We theoretically and experimentally investigate aspects such as unidirectional signal transfer, energy efficiency and networking effects, among others, and we present their basic theoretical formalisms and describe demonstrations of practical applications. A stochastic analysis of light-assisted material formation is also presented, where an information-based approach provides a deeper understanding of the phenomena involved, such as self-organization. Furthermore, the spatio-temporal dynamics of optical excitation transfer and its inherent stochastic attributes are utilized for solution searching, paving the way to a novel computing paradigm that exploits coherent and dissipative processes in nanophotonics.
Computational nanoelectronics towards: design, analysis, synthesis, and fundamental limits
Klimeck, G.
2003-01-01
This seminar will review the development of a comprehensive nanoelectronic modeling tool (NEMO 1-D and NEMO 3-D) and its application to high-speed electronics (resonant tunneling diodes) and IR detectors and lasers (quantum dots and 1-D heterostructures).
Fundamental electronic mechanisms limiting the performance of solar cells
Lindholm, F. A.; Sah, C.-T.
1977-01-01
Attention is focused on distortion in the energy band, and carrier recombination and generation rates (lifetimes), as the two dominant mechanisms. Spatial dependences associated with these two mechanisms, in the direction normal to the surface illuminated by the sun and in the direction tangential to that surface, are also emphasized as crucial factors in governing the efficiency of solar cells. Electronic parameters for the set of differential equations characterizing transport, recombination, and generation of carriers, and interband and band-bound transition rates, are studied.
Surpassing Fundamental Limits of Oscillators Using Nonlinear Resonators
Villanueva, L. G.; Kenig, E.; Karabalin, R. B.; Matheny, M. H.; Lifshitz, R; Cross, M. C.; Roukes, M. L.
2013-01-01
Self-sustained oscillators are ubiquitous and essential for metrology, communications, time reference, and geolocation. In its most basic form an oscillator consists of a resonator driven on-resonance, through feedback, to create a periodic signal sustained by a static energy source. The generation of a stable frequency, the basic function of oscillators, is typically achieved by increasing the amplitude of motion of the resonator while remaining within its linear, harmonic, regime. Contrary ...
Fundamental Limitations to Gain Enhancement in Periodic Media and Waveguides
DEFF Research Database (Denmark)
Grgic, Jure; Ott, Johan Raunkjær; Wang, Fengwen;
2012-01-01
A common strategy to compensate for losses in optical nanostructures is to add gain material in the system. By exploiting slow-light effects it is expected that the gain may be enhanced beyond its bulk value. Here we show that this route cannot be followed uncritically: inclusion of gain inevitably...... stacks, and photonic crystal waveguides). Nevertheless, a small amount of added gain may be beneficial....
Fundamental limitations to gain enhancement in periodic media and waveguides
Grgić, Jure; Wang, Fengwen; Sigmund, Ole; Jauho, Antti-Pekka; Mørk, Jesper; Mortensen, N Asger
2012-01-01
A common strategy to compensate for losses in optical nanostructures is to add gain material in the system. By exploiting slow-light effects it is expected that the gain may be enhanced beyond its bulk value. Here we show that this route cannot be followed uncritically: inclusion of gain inevitably modifies the underlying dispersion law, and thereby may degrade the slow-light properties underlying the device operation and the anticipated gain enhancement itself. This degradation is generic; we demonstrate it for three different systems of current interest (coupled resonator optical waveguides, Bragg stacks, and photonic crystal waveguides). Nevertheless, a small amount of added gain may be beneficial.
Fundamental Limits of Data Analytics in Sociotechnical Systems
Varshney, Lav R.
2016-01-01
In the Big Data era, informational systems involving humans and machines are being deployed in multifarious societal settings. Many use data analytics as subcomponents for descriptive, predictive, and prescriptive tasks, often trained using machine learning. Yet when analytics components are placed in large-scale sociotechnical systems, it is often difficult to characterize how well the systems will act, measured with criteria relevant in the world. Here, we propose a system modeling techniqu...
Airport Noise Tech Challenge Overview
Bridges, James
2011-01-01
The Supersonics Project, operating under NASA Aeronautics Mission Directorate#s Fundamental Aero Program, has been organized around the Technical Challenges that have historically precluded commercial supersonic flight. One of these Challenges is making aircraft that are capable of such high aerodynamic performance quiet enough around airports that they will not be objectionable. It is recognized that a successful civilian supersonic aircraft will be a system where many new technologies will come together, and for this to happen not only will new low noise propulsion concepts be required, but new engineering tools that predict the noise of the aircraft as these technologies are combined and compromised with the rest of the aircraft design. These are the two main objectives of the Airport Noise Tech Challenge. " ! As a Project in the Fundamental Aero Program, we work at a relatively low level of technology readiness. However, we have high level milestones which force us to integrate our efforts to impact systems-level activities. To keep the low-level work tied to delivering engineering tools and low-noise concepts, we have structured our milestones around development of the concepts and organized our activities around developing and applying our engineering tools to these concepts. The final deliverables in these milestones are noise prediction modules validated against the best embodiment of each concept. These will then be used in cross-disciplinary exercises to demonstrate the viability of aircraft designs to meet all the Technical Challenges. Some of the concepts being developed are shown: Fan Flow Diverters, Multi-jet Shielding, High-Aspect Ratio Embedded Nozzles, Plasma Actuated Instability Manipulation, Highly Variable Cycle Mixer- Ejectors, and Inverted Velocity Profiles. These concepts are being developed for reduced jet noise along with the design tools which describe how they perform when used in various aircraft configurations. Several key upcoming
Local noise in a diffusive conductor
Tikhonov, E. S.; Shovkun, D. V.; Ercolani, D.; Rossella, F.; Rocci, M.; Sorba, L.; Roddaro, S.; Khrapai, V. S.
2016-07-01
The control and measurement of local non-equilibrium configurations is of utmost importance in applications on energy harvesting, thermoelectrics and heat management in nano-electronics. This challenging task can be achieved with the help of various local probes, prominent examples including superconducting or quantum dot based tunnel junctions, classical and quantum resistors, and Raman thermography. Beyond time-averaged properties, valuable information can also be gained from spontaneous fluctuations of current (noise). From these perspective, however, a fundamental constraint is set by current conservation, which makes noise a characteristic of the whole conductor, rather than some part of it. Here we demonstrate how to remove this obstacle and pick up a local noise temperature of a current biased diffusive conductor with the help of a miniature noise probe. This approach is virtually noninvasive for the electronic energy distributions and extends primary local measurements towards strongly non-equilibrium regimes.
Brownian Ratchets: Transport Controlled by Thermal Noise
Kula, J.; Czernik, T.; Łuczka, J.
1998-02-01
We analyze directed transport of overdamped Brownian particles in a 1D spatially periodic potential that are subjected to both zero-mean thermal equilibrium Nyquist noise and zero-mean exponentially correlated dichotomous fluctuations. We show that particles can reverse the direction of average motion upon a variation of noise parameters if two fundamental symmetries, namely, the reflection symmetry of the spatial periodic structure, and the statistical symmetry of dichotomous fluctuations, are broken. There is a critical thermal noise intensity Dc, or equivalently a critical temperature Tc, at which the mean velocity of particles is zero. Below Tc and above Tc particles move in opposite directions. At fixed temperature, there is a region of noise parameters in which particles of different linear size are transported in opposite directions.
Local noise in a diffusive conductor
Tikhonov, E. S.; Shovkun, D. V.; Ercolani, D.; Rossella, F.; Rocci, M.; Sorba, L.; Roddaro, S.; Khrapai, V. S.
2016-01-01
The control and measurement of local non-equilibrium configurations is of utmost importance in applications on energy harvesting, thermoelectrics and heat management in nano-electronics. This challenging task can be achieved with the help of various local probes, prominent examples including superconducting or quantum dot based tunnel junctions, classical and quantum resistors, and Raman thermography. Beyond time-averaged properties, valuable information can also be gained from spontaneous fluctuations of current (noise). From these perspective, however, a fundamental constraint is set by current conservation, which makes noise a characteristic of the whole conductor, rather than some part of it. Here we demonstrate how to remove this obstacle and pick up a local noise temperature of a current biased diffusive conductor with the help of a miniature noise probe. This approach is virtually noninvasive for the electronic energy distributions and extends primary local measurements towards strongly non-equilibrium regimes. PMID:27466216
Local noise in a diffusive conductor.
Tikhonov, E S; Shovkun, D V; Ercolani, D; Rossella, F; Rocci, M; Sorba, L; Roddaro, S; Khrapai, V S
2016-07-28
The control and measurement of local non-equilibrium configurations is of utmost importance in applications on energy harvesting, thermoelectrics and heat management in nano-electronics. This challenging task can be achieved with the help of various local probes, prominent examples including superconducting or quantum dot based tunnel junctions, classical and quantum resistors, and Raman thermography. Beyond time-averaged properties, valuable information can also be gained from spontaneous fluctuations of current (noise). From these perspective, however, a fundamental constraint is set by current conservation, which makes noise a characteristic of the whole conductor, rather than some part of it. Here we demonstrate how to remove this obstacle and pick up a local noise temperature of a current biased diffusive conductor with the help of a miniature noise probe. This approach is virtually noninvasive for the electronic energy distributions and extends primary local measurements towards strongly non-equilibrium regimes.
Fundamental plasma emission involving ion sound waves
Cairns, Iver H.
1987-01-01
The theory for fundamental plasma emission by the three-wave processes L + or - S to T (where L, S and T denote Langmuir, ion sound and transverse waves, respectively) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. In addition the rates, path-integrated wave temperatures, and limits on the brightness temperature of the radiation are derived.
Laser-fundamentals and applications
Energy Technology Data Exchange (ETDEWEB)
Schinagl, W.
1982-09-01
The survey article gives an introduction to laser technology. Fundamentals and physical aspects are discussed at large. After a brief historical review and a discussion of the physical fundamentals, important types of laser, characteristics of laser radiation and its applications in medicine are discussed.
The Subordination of Aesthetic Fundamentals in College Art Instruction
Lavender, Randall
2003-01-01
Opportunities for college students of art and design to study fundamentals of visual aesthetics, integrity of form, and principles of composition are limited today by a number of factors. With the well-documented prominence of postmodern critical theory in the world of contemporary art, the study of aesthetic fundamentals is largely subordinated…
The Fundamental Scale of Descriptions
Febres, Gerardo
2014-01-01
The complexity of a system description is a function of the entropy of its symbolic description. Prior to computing the entropy of the system description, an observation scale has to be assumed. In natural language texts, typical scales are binary, characters, and words. However, considering languages as structures built around certain preconceived set of symbols, like words or characters, is only a presumption. This study depicts the notion of the Description Fundamental Scale as a set of symbols which serves to analyze the essence a language structure. The concept of Fundamental Scale is tested using English and MIDI music texts by means of an algorithm developed to search for a set of symbols, which minimizes the system observed entropy, and therefore best expresses the fundamental scale of the language employed. Test results show that it is possible to find the Fundamental Scale of some languages. The concept of Fundamental Scale, and the method for its determination, emerges as an interesting tool to fac...
Vibration and noise analysis of a gear transmission system
Choy, F. K.; Qian, W.; Zakrajsek, J. J.; Oswald, F. B.
1993-01-01
This paper presents a comprehensive procedure to predict both the vibration and noise generated by a gear transmission system under normal operating conditions. The gearbox vibrations were obtained from both numerical simulation and experimental studies using a gear noise test rig. In addition, the noise generated by the gearbox vibrations was recorded during the experimental testing. A numerical method was used to develop linear relationships between the gearbox vibration and the generated noise. The hypercoherence function is introduced to correlate the nonlinear relationship between the fundamental noise frequency and its harmonics. A numerical procedure was developed using both the linear and nonlinear relationships generated from the experimental data to predict noise resulting from the gearbox vibrations. The application of this methodology is demonstrated by comparing the numerical and experimental results from the gear noise test rig.
Investigation of Noise in Electronic Ultrasonic Systems
Directory of Open Access Journals (Sweden)
Paulius Adomavičius
2011-03-01
Full Text Available Noise models in ultrasonic control system have been investigated. Ultrasonic system channel consist of exciting generator, ultrasonic transducer, amplitude limiter, amplifier, low band filter and A/D converter. The ultrasonic transducers have been described as Von Hippel model, Van Dyke model or improved Van Dyke model. Advantages and disadvantages of these models are discussed in this paper. Noise models of amplitude limiter and linear operational amplifier are presented. The summary results of calculated noise spectral density of ultrasonic system channel have been presented.Article in Lithuanian
Shot noise of a quantum shuttle
DEFF Research Database (Denmark)
Novotny, Tomas; Donarini, Andrea; Flindt, Christian
2004-01-01
even in the quantum limit, confirming that shuttling is universally a low noise phenomenon. In approaching the semiclassical limit, the Fano factor shows a giant enhancement (Fsimilar or equal to10(2)) at the shuttling threshold, consistent with predictions based on phase-space representations......We formulate a theory for shot noise in quantum nanoelectromechanical systems. As a specific example, the theory is applied to a quantum shuttle, and the zero-frequency noise, measured by the Fano factor F, is computed. F reaches very low values (Fsimilar or equal to10(-2)) in the shuttling regime...
Elgaroy, E O
2013-01-01
Solar Noise Storms examines the properties and features of solar noise storm phenomenon. The book also presents some theories that can be used to gain a better understanding of the phenomenon. The coverage of the text includes topics that cover the features and behavior of noise storms, such as the observable features of noise storms; the relationship between noise storms and the observable features on the sun; and ordered behavior of storm bursts in the time-frequency plane. The book also covers the spectrum, polarization, and directivity of noise storms. The text will be of great use to astr
Nonlinear phonon interferometry at the Heisenberg limit
Cheung, Hil F. H.; Patil, Yogesh Sharad; Chang, Laura; Chakram, Srivatsan; Vengalattore, Mukund
2016-05-01
Interferometers operating at or close to quantum limits of precision have found wide application in tabletop searches for physics beyond the standard model, the study of fundamental forces and symmetries of nature and foundational tests of quantum mechanics. The limits imposed by quantum fluctuations and measurement backaction on conventional interferometers (δϕ 1 /√{ N}) have spurred the development of schemes to circumvent these limits through quantum interference, multiparticle interactions and entanglement. Here, we realize a prominent example of such schemes, the so-called SU(1,1) interferometer, in a fundamentally new platform in which the interfering arms are distinct flexural modes of a millimeter-scale mechanical resonator. We realize up to 15.4(3) dB of noise squeezing and demonstrate the Heisenberg scaling of interferometric sensitivity (δϕ 1 / N), corresponding to a 6-fold improvement in measurement precision over a conventional interferometer. We describe how our work extends the optomechanical toolbox and how it presents new avenues for studies of optomechanical sensing and studies of nonequilibrium dynamics of multimode optomechanical systems. This work was supported by the DARPA QuASAR program through a grant from the ARO, the ARO MURI on non-equilibrium manybody dynamics and an NSF INSPIRE award.
Generalized FMD Detection for Spectrum Sensing Under Low Signal-to-Noise Ratio
Lin, Feng; Hu, Zhen; Hou, Shujie; Browning, James P; Wicks, Michael C
2012-01-01
Spectrum sensing is a fundamental problem in cognitive radio. We propose a function of covariance matrix based detection algorithm for spectrum sensing in cognitive radio network. Monotonically increasing property of function of matrix involving trace operation is utilized as the cornerstone for this algorithm. The advantage of proposed algorithm is it works under extremely low signal-to-noise ratio, like lower than -30 dB with limited sample data. Theoretical analysis of threshold setting for the algorithm is discussed. A performance comparison between the proposed algorithm and other state-of-the-art methods is provided, by the simulation on captured digital television (DTV) signal.
Flow induced noise modelling for industrial piping systems
Gijrath, H.; Ǎbom, M.
2003-01-01
Noise from e.g. gas-transport piping systems becomes more and more a problem for plants located close to urban areas. Too high noise levels are unacceptable and will put limitations on the plant capacity. Flow-induced noise of valves, orifices and headers installed in the installation plays a domina
EURailNoise: a study of European priorities and strategies for railway noise abatement
Kalivoda, M.; Danneskiold-Samsøe, U.; Krüger, F.; Barsikow, B.
2003-10-01
The European Union is developing its noise policy by using a number of expert groups on specific noise issues. One of the most relevant noise problems is railway traffic which is dealt with by Working Group 6 (WG 6). The Commission of the European Union appointed a consortium of six consultants and experts in railway noise to prepare a study on European priorities and strategies for railway noise abatement. The main purpose of this study was to support the work within WG 6 and to create an inventory of measures for future railway noise abatement policy of the European Union. The EURailNoise study was to be completed in autumn 2001. The countries included the European Union member states, together with Norway, and Switzerland, and three prospective members (Hungary, the Czech Republic, and Poland). The EURailNoise study consisted of three main parts. The baseline was a review of current European legislation on railway noise generation as well as noise perception. In parallel a documentation of cases, where technical measures against railway noise had been successfully applied, was prepared using a classification of "good practice", "promising new technology", and "promising research results". The second part covered the potential for further noise reduction demonstrated for High Speed Passenger Traffic, S-Trains, Locomotives, Trams, Freight Traffic, Track Design and finally Wheels and Track Monitoring and Maintenance. Thirdly, a strategy for future activities of the Commission concerning the reduction of rail noise was to be proposed including a proposal for noise emission limits. This paper summarizes the results of the EURailNoise study.
Fundamental principles of heat transfer
Whitaker, Stephen
1977-01-01
Fundamental Principles of Heat Transfer introduces the fundamental concepts of heat transfer: conduction, convection, and radiation. It presents theoretical developments and example and design problems and illustrates the practical applications of fundamental principles. The chapters in this book cover various topics such as one-dimensional and transient heat conduction, energy and turbulent transport, forced convection, thermal radiation, and radiant energy exchange. There are example problems and solutions at the end of every chapter dealing with design problems. This book is a valuable int
Fundamentals of technology project management
Garton, Colleen
2012-01-01
Designed to provide software engineers, students, and IT professionals with an understanding of the fundamentals of project management in the technology/IT field, this book serves as a practical introduction to the subject. Updated with information on how Fundamentals of Project Management integrates with and complements Project Management Institute''s Project Management Body of Knowledge, this collection explains fundamental methodologies and techniques while also discussing new technology, tools, and virtual work environments. Examples and case studies are based on technology projects, and t
Energy Technology Data Exchange (ETDEWEB)
Garrido Quevedo, D.
2013-07-01
The aim is to confirm through real trials that the design and the results obtained through simulation conform to reality with a high degree of confidence... The combination of tests on scale models and the validation of the methods of calculation are necessary tools for the design of limiters impact a container of spent fuel transport.
Critical petermann K factor for intensity noise squeezing
van Der Lee AM; van Druten NJ; van Exter MP; Woerdman; Poizat; Grangier
2000-11-27
We investigate the impact of the Petermann-excess-noise factor K>/=1 on the possibility of intensity noise squeezing of laser light below the standard quantum limit. Using an N-mode model, we show that squeezing is limited to a floor level of 2(K-1) times the shot noise limit. Thus, even a modest Petermann factor significantly impedes squeezing, which becomes impossible when K>/=1.5. This appears as a serious limitation for obtaining sub-shot-noise light from practical semiconductor lasers. We present experimental evidence for our theory.
Local noise sensitivity: Insight into the noise effect on chaotic dynamics.
Sviridova, Nina; Nakamura, Kazuyuki
2016-12-01
Noise contamination in experimental data with underlying chaotic dynamics is one of the significant problems limiting the application of many nonlinear time series analysis methods. Although numerous studies have been devoted to the investigation of different aspects of noise-nonlinear dynamics interactions, the effects produced by noise on chaotic dynamics are not fully understood. This study sought to analyze the local effects produced by noise on chaotic dynamics with a smooth attractor. Local Wayland test translation errors were calculated for noise-induced Lorenz and Rössler chaotic models, and for experimental green light photoplethysmogram data. Results demonstrated that under noise induction, local regions on the chaotic attractor with high values of local translation error can be observed. This phenomenon was defined as the local noise sensitivity. It was found that for both models, local noise-sensitive regions were located close to the system's equilibrium points. Additionally, it was found that the reconstructed dynamics represent well the local noise sensitivity of the original dynamics. The concept of local noise sensitivity is expected to contribute to various applied studies, as it reveals regions of chaotic attractors that are sensitive to the presence of noise.
Spin Noise Exchange in Coupled Alkali-Metal Vapors
Dellis, A T; Kominis, I K
2013-01-01
The physics of spin exchange collisions has fueled a large number of discoveries in fundamental physics, chemistry and biology, and has led to several applications in medical imaging and nuclear magnetic resonance. We here report on the experimental observation and theoretical justification of a novel effect, the transfer of spin noise from one atomic species to another, through the mechanism of spin exchange. Essentially, we extend the foundational studies of spin exchange into the deeper layer of quantum fluctuations. The signature of spin noise exchange is an increase of the total spin noise power at low magnetic fields where the two-species spin noise resonances overlap.
The Fundamental Role of Wide-Field Imaging in Space Situational Awareness
McGraw, J. T.; Ackermann, M.; Zimmer, P.
Space Situational Awareness (SSA) is fundamentally based upon surveillance of the variety of objects moving in Earth orbital space: functioning satellites, derelicts, and space debris. Optical telescopes provide a significant fraction of all data for the surveillance of space, and virtually all data on GEO and related objects. Starting with an operational definition of surveillance of space (SoS), we discuss: The unique role of wide-field imaging in acquiring surveillance data The detector-driven optical design of small, wide-field telescopes that produce data capable of providing high signal-to-noise images and tracks in the presence of detector and complicated background noise Multiple sky tracking and detector readout combinations to optimize object detection from LEO through GEO The approach to real-time image data processing capable of enabling rapid analysis and decision-making, as needed. Specifically, we describe the fundamental physics associated with the design of optical surveillance cameras based upon small aperture, wide field-of-view telescopes which we have designed. Critical performance issues include uncued detection of new and/or un-cataloged objects to faint limiting magnitudes (V > 18 at LEO), including initial orbit determination, and the capability to survey large areas of the sky (such as the CONUS GEO belt of approximately 1800 sq. degrees) to faint limiting magnitudes (V = 18) every two hours. The goal is to convert these data into actionable information in very near real-time. Initial data demonstrating and supporting our surveillance of space system designs and design goals will be presented.
Polarization of electric field noise near metallic surfaces
Schindler, Philipp; Daniilidis, Nikos; Häffner, Hartmut
2015-01-01
Electric field noise in proximity to metallic surfaces is a poorly understood phenomenon that appears in different areas of physics. Trapped ion quantum information processors are particular susceptible to this noise, leading to motional decoherence which ultimately limits the fidelity of quantum operations. On the other hand they present an ideal tool to study this effect, opening new possibilities in surface science. In this work we analyze and measure the polarization of the noise field in a micro-fabricated ion trap for various noise sources. We find that technical noise sources and noise emanating directly from the surface give rise to different degrees of polarization which allows us to differentiate between the two noise sources. Based on this, we demonstrate a method to infer the magnitude of surface noise in the presence of technical noise.
A Goldilocks principle for modeling radial velocity noise
Feng, Fabo; Jones, H R A; Butler, R P; Vogt, S
2016-01-01
The doppler measurements of stars are diluted and distorted by stellar activity noise. Different choices of noise models and statistical methods have led to much controversy in the confirmation of exoplanet candidates obtained through analysing radial velocity data. To quantify the limitation of various models and methods, we compare different noise models and signal detection criteria for various simulated and real data sets in the Bayesian framework. According to our analyses, the white noise model tend to interpret noise as signal, leading to false positives. On the other hand, the red noise models are likely to interprete signal as noise, resulting in false negatives. We find that the Bayesian information criterion combined with a Bayes factor threshold of 150 can efficiently rule out false positives and confirm true detections. We further propose a Goldilocks principle aimed at modeling radial velocity noise to avoid too many false positives and too many false negatives. We propose that the noise model w...