Universal parametrization for quark and lepton substructure

International Nuclear Information System (INIS)

Akama, Keiichi; Terazawa, Hidezumi.

1994-01-01

A universal parametrization for possible quark and lepton substructure is advocated in terms of quark and lepton form factors. It is emphasized that the lower bounds on compositeness scale, Λ c , to be determined experimentally strongly depend on their definitions in composite models. From the recent HERA data, it is estimated to be Λ c > 50 GeV, 0.4 TeV and 10 TeV, depending on the parametrizations with a single-pole form factor, a contact interaction and a logarithmic form factor, respectively. (author)

Non-Parametric Analysis of Rating Transition and Default Data

DEFF Research Database (Denmark)

Fledelius, Peter; Lando, David; Perch Nielsen, Jens

2004-01-01

We demonstrate the use of non-parametric intensity estimation - including construction of pointwise confidence sets - for analyzing rating transition data. We find that transition intensities away from the class studied here for illustration strongly depend on the direction of the previous move b...

Variance in parametric images: direct estimation from parametric projections

International Nuclear Information System (INIS)

Maguire, R.P.; Leenders, K.L.; Spyrou, N.M.

2000-01-01

Recent work has shown that it is possible to apply linear kinetic models to dynamic projection data in PET in order to calculate parameter projections. These can subsequently be back-projected to form parametric images - maps of parameters of physiological interest. Critical to the application of these maps, to test for significant changes between normal and pathophysiology, is an assessment of the statistical uncertainty. In this context, parametric images also include simple integral images from, e.g., [O-15]-water used to calculate statistical parametric maps (SPMs). This paper revisits the concept of parameter projections and presents a more general formulation of the parameter projection derivation as well as a method to estimate parameter variance in projection space, showing which analysis methods (models) can be used. Using simulated pharmacokinetic image data we show that a method based on an analysis in projection space inherently calculates the mathematically rigorous pixel variance. This results in an estimation which is as accurate as either estimating variance in image space during model fitting, or estimation by comparison across sets of parametric images - as might be done between individuals in a group pharmacokinetic PET study. The method based on projections has, however, a higher computational efficiency, and is also shown to be more precise, as reflected in smooth variance distribution images when compared to the other methods. (author)

Parametric methods for spatial point processes

DEFF Research Database (Denmark)

Møller, Jesper

is studied in Section 4, and Bayesian inference in Section 5. On one hand, as the development in computer technology and computational statistics continues,computationally-intensive simulation-based methods for likelihood inference probably will play a increasing role for statistical analysis of spatial...... inference procedures for parametric spatial point process models. The widespread use of sensible but ad hoc methods based on summary statistics of the kind studied in Chapter 4.3 have through the last two decades been supplied by likelihood based methods for parametric spatial point process models......(This text is submitted for the volume ‘A Handbook of Spatial Statistics' edited by A.E. Gelfand, P. Diggle, M. Fuentes, and P. Guttorp, to be published by Chapmand and Hall/CRC Press, and planned to appear as Chapter 4.4 with the title ‘Parametric methods'.) 1 Introduction This chapter considers...

Parametric and Non-Parametric System Modelling

DEFF Research Database (Denmark)

Nielsen, Henrik Aalborg

1999-01-01

the focus is on combinations of parametric and non-parametric methods of regression. This combination can be in terms of additive models where e.g. one or more non-parametric term is added to a linear regression model. It can also be in terms of conditional parametric models where the coefficients...... considered. It is shown that adaptive estimation in conditional parametric models can be performed by combining the well known methods of local polynomial regression and recursive least squares with exponential forgetting. The approach used for estimation in conditional parametric models also highlights how...... networks is included. In this paper, neural networks are used for predicting the electricity production of a wind farm. The results are compared with results obtained using an adaptively estimated ARX-model. Finally, two papers on stochastic differential equations are included. In the first paper, among...

Interplay between parametric instabilities in fusion - relevant laser plasmas

International Nuclear Information System (INIS)

Huller, St.

2003-01-01

The control of parametric instabilities plays an important role in laser fusion. They are driven by the incident laser beams in the underdense plasma surrounding a fusion capsule and hinder the absorption process of incident laser light which is necessary to heat the fusion target. Due to its high intensity and power, the laser light modifies the plasma density dynamically, such that two or more parametric instabilities compete, in particular stimulated Brillouin scattering and the filamentation instability. The complicated interplay between these parametric instabilities is studied in detail by developing an adequate model accompanied by numerical simulations with multidimensional codes. The model is applied to generic and to smoothed laser beams, which are necessary to limit parametric instabilities, with parameters close to experimental conditions. (author)

Creating Efficient Instrumentation Networks to Support Parametric Risk Transfer

Science.gov (United States)

Rockett, P.

2009-04-01

The development and institutionalisation of Catastrophe modelling during the 1990s opened the way for Catastrophe risk securitization transactions in which catastrophe risk held by insurers is transferred to the capital markets in the form of a bond. Cat Bonds have been one of the few areas of the capital markets in which the risk modelling has remained secure and the returns on the bonds have held up well through the 2008 Credit Crunch. There are three ways of structuring the loss triggers on bonds: ‘indemnity triggers' - reflecting the actual losses to the issuers; ‘index triggers' reflecting the losses to some index such as reported insurance industry loss and ‘parametric triggers' reflecting the parameters of the underlying catastrophe event itself. Indemnity triggers require that the investors trust that the insurer is reporting all their underlying exposures, while both indemnity and index losses may take 1-2 years to settle before all the claims are reported and resolved. Therefore parametric structures have many advantages, in particular in that the bond can be settled rapidly after an event. The challenge is to create parametric indices that closely reflect the actual losses to the insurer - ie that minimise ‘basis risk'. First generation parametric indices had high basis risk as they were crudely based on the magnitude of an earthquake occurring within some defined geographical box, or the intensity of a hurricane relative to the distance of the storm from some location. Second generation triggers involve taking measurements of ground motion or windspeed or flood depths at many locations and weighting each value so that the overall index closely mimics insurance loss. Cat bonds with second generation parametric triggers have been successfully issued for European Windstorm, UK Flood and California and Japan Earthquake. However the spread of second generation parametric structures is limited by the availability of suitable networks of

Using non-parametric methods in econometric production analysis

DEFF Research Database (Denmark)

Czekaj, Tomasz Gerard; Henningsen, Arne

2012-01-01

by investigating the relationship between the elasticity of scale and the farm size. We use a balanced panel data set of 371~specialised crop farms for the years 2004-2007. A non-parametric specification test shows that neither the Cobb-Douglas function nor the Translog function are consistent with the "true......Econometric estimation of production functions is one of the most common methods in applied economic production analysis. These studies usually apply parametric estimation techniques, which obligate the researcher to specify a functional form of the production function of which the Cobb...... parameter estimates, but also in biased measures which are derived from the parameters, such as elasticities. Therefore, we propose to use non-parametric econometric methods. First, these can be applied to verify the functional form used in parametric production analysis. Second, they can be directly used...

On the problem of neutron spectroscopy of parametrically non-equilibrium quasiparticles in solids

International Nuclear Information System (INIS)

Vo Khong An'.

1981-01-01

A suitable for numerical estimations formula for coherent neutron inelastic scattering cross sections on the plasmon-phonon mixed modes of electron-phonon systems in the parametric resonance conditions is obtained from the analytical one presented in the previous work using some relations of the general parametric excitation theory. The cross sections of neutron scattering on the high-frequency plasmon-like and the low-frequency longitudinal optical phonon-like modes in InSb crystals are calculated as functions of the driving laser field intensity, which show an increase in values by about two orders of magnitude as the field intensity approaches the parametric excitation threshold

Implementing quantum optics with parametrically driven superconducting circuits

Science.gov (United States)

Aumentado, Jose

Parametric coupling has received much attention, in part because it forms the core of many low-noise amplifiers in superconducting quantum information experiments. However, parametric coupling in superconducting circuits is, as a general rule, simple to generate and forms the basis of a methodology for interacting microwave fields at different frequencies. In the quantum regime, this has important consequences, allowing relative novices to do experiments in superconducting circuits today that were previously heroic efforts in quantum optics and cavity-QED. In this talk, I'll give an overview of some of our work demonstrating parametric coupling within the context of circuit-QED as well as some of the possibilities this concept creates in our field.

Comparing parametric and nonparametric regression methods for panel data

DEFF Research Database (Denmark)

Czekaj, Tomasz Gerard; Henningsen, Arne

We investigate and compare the suitability of parametric and non-parametric stochastic regression methods for analysing production technologies and the optimal firm size. Our theoretical analysis shows that the most commonly used functional forms in empirical production analysis, Cobb......-Douglas and Translog, are unsuitable for analysing the optimal firm size. We show that the Translog functional form implies an implausible linear relationship between the (logarithmic) firm size and the elasticity of scale, where the slope is artificially related to the substitutability between the inputs....... The practical applicability of the parametric and non-parametric regression methods is scrutinised and compared by an empirical example: we analyse the production technology and investigate the optimal size of Polish crop farms based on a firm-level balanced panel data set. A nonparametric specification test...

Parametric Design of Outdoor Broadcasting Studio Based on Schema Theory

Directory of Open Access Journals (Sweden)

Zhu Li

2016-01-01

Full Text Available This paper mainly demonstrates that the schema is an important way for the architect to cognize architecture form logic. It connects schema to algorithm of parametric design in order to seek the “algorithm schema” generation in parametric design of architecture. Meanwhile, this paper discusses the generative process and methods of the “algorithm schema” in parametric design of architecture by describing a case of outdoor broadcasting studio of Hunan Economic Radio. It also reveals the importance of “algorithm schema” for the cognition and architectural form logic generation.

Experimental investigation of saturation effect on pump-to-signal intensity modulation transfer in single-pump phase-insensitive fiber optic parametric amplifiers

DEFF Research Database (Denmark)

Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke

2013-01-01

We present an experimental characterization of how signal gain saturation affects the transfer of intensity modulation from the pump to the signal in single-pump, phase-insensitive fiber optic parametric amplifiers (FOPAs). In this work, we demonstrate experimentally for the first time, to our...... knowledge, how gain saturation of a FOPA reduces the noise contribution due to the transfer of pump power fluctuations to the signal. In a particular example, it is shown that the transferred noise is significantly reduced by a factor of 3, while the FOPA gain remains above 10 dB....

Schwinger-type parametrization of open string worldsheets

Directory of Open Access Journals (Sweden)

Sam Playle

2017-03-01

Full Text Available A parametrization of (super moduli space near the corners corresponding to bosonic or Neveu–Schwarz open string degenerations is introduced for worldsheets of arbitrary topology. With this parametrization, Feynman graph polynomials arise as the α′→0 limit of objects on moduli space. Furthermore, the integration measures of string theory take on a very simple and elegant form.

On Parametric (and Non-Parametric Variation

Directory of Open Access Journals (Sweden)

Neil Smith

2009-11-01

Full Text Available This article raises the issue of the correct characterization of ‘Parametric Variation’ in syntax and phonology. After specifying their theoretical commitments, the authors outline the relevant parts of the Principles–and–Parameters framework, and draw a three-way distinction among Universal Principles, Parameters, and Accidents. The core of the contribution then consists of an attempt to provide identity criteria for parametric, as opposed to non-parametric, variation. Parametric choices must be antecedently known, and it is suggested that they must also satisfy seven individually necessary and jointly sufficient criteria. These are that they be cognitively represented, systematic, dependent on the input, deterministic, discrete, mutually exclusive, and irreversible.

Pre-Rationalized Parametric Designing of Roof Shells Formed by Repetitive Modules of Catalan Surfaces

Directory of Open Access Journals (Sweden)

Jolanta Dzwierzynska

2018-04-01

Full Text Available The aim of the study is to develop an original, methodical, and practical approach to the early stages of parametric design of roof shells formed by repetitive modules of Catalan surfaces. It is presented on the example of designing the roof shells compound of four concrete elements. The designing process proposed by us consists in linking geometric shaping of roofs’ models with their structural analysis and optimization. Contrary to other methods, which use optimization process in order to find free roof forms, we apply it in order to explore and improve design alternatives. It is realized with the application of designing tools working in Rhinoceros 3D software. The flexible scripts elaborated by us, in order to achieve roofs’ models of regular and symmetrical shapes, are converted into simulation models to perform structural analysis. It is mainly focused on how the roof shells perform dependently on their geometric characteristics. The simulation enables one to evaluate various roof shells’ shapes, as well as to select an optimal design solution. The proposed approach to the conceptual design process may drive the designing to achieve geometric and structural forms which not only follow the design intentions but also target better results.

Using non-parametric methods in econometric production analysis

DEFF Research Database (Denmark)

Czekaj, Tomasz Gerard; Henningsen, Arne

Econometric estimation of production functions is one of the most common methods in applied economic production analysis. These studies usually apply parametric estimation techniques, which obligate the researcher to specify the functional form of the production function. Most often, the Cobb...... results—including measures that are of interest of applied economists, such as elasticities. Therefore, we propose to use nonparametric econometric methods. First, they can be applied to verify the functional form used in parametric estimations of production functions. Second, they can be directly used...

Parametric interaction of waves in the plasma with random large-scale inhomogeneities

International Nuclear Information System (INIS)

Abramovich, B.S.; Tamojkin, V.V.

1980-01-01

Parametric processes of the decay and fusion of three waves in a weakly turbulent plasma with random inhomogeneities, the size of which is too big as compared with wave-lengths are considered. Under the diffusive approximation applicability closed equations are obtained, which determine the behaviour of all the intensity moments of parametrically bound waves. It is shown that under the conditions when the characteristic length of the multiple scattering is considerably less than the nonlinear interaction, length the effective increment of average intensity increase and its moments at dissociation processes is too small as compared with the homogeneous plasma case. At fusion processes the same increment (decrement) determines the distance at which all intensity moments are in the saturation regime

Parametric trapping of electromagnetic waves in an inhomogeneous plasma

International Nuclear Information System (INIS)

Silin, V.P.; Starodub, A.N.

1977-01-01

Considered is parametric instability in an inhomogeneous plasma at which a pumping wave is transformed to an electromagnetic wave and aperiodically in-time-growing disturbances. It is shown that after achievement of some boundary pumping value by electric field intensity an absolute parametric instability evolution becomes possible. In-time growing plasma disturbances are localized near electric field extremums of a pumping wave. Such localization areas are small as compared to characteristic size of pumping inhomogeneity in a plasma. The secondary electromagnetic waves stay within the localization areas and, therefore, are not scattered by a plasma. As following from this it has been established, that due to parametric instability electromagnetic radiation trapping by a plasma occurs. Such a trapping is considerably connected with a spatial structure of a pumping field and it cannot arise within the field of a running wave in the theoretical model considered. However parametric trapping turns out to be possible even with very small reflection coefficients

A generalized parametric response mapping method for analysis of multi-parametric imaging: A feasibility study with application to glioblastoma.

Science.gov (United States)

Lausch, Anthony; Yeung, Timothy Pok-Chi; Chen, Jeff; Law, Elton; Wang, Yong; Urbini, Benedetta; Donelli, Filippo; Manco, Luigi; Fainardi, Enrico; Lee, Ting-Yim; Wong, Eugene

2017-11-01

Parametric response map (PRM) analysis of functional imaging has been shown to be an effective tool for early prediction of cancer treatment outcomes and may also be well-suited toward guiding personalized adaptive radiotherapy (RT) strategies such as sub-volume boosting. However, the PRM method was primarily designed for analysis of longitudinally acquired pairs of single-parameter image data. The purpose of this study was to demonstrate the feasibility of a generalized parametric response map analysis framework, which enables analysis of multi-parametric data while maintaining the key advantages of the original PRM method. MRI-derived apparent diffusion coefficient (ADC) and relative cerebral blood volume (rCBV) maps acquired at 1 and 3-months post-RT for 19 patients with high-grade glioma were used to demonstrate the algorithm. Images were first co-registered and then standardized using normal tissue image intensity values. Tumor voxels were then plotted in a four-dimensional Cartesian space with coordinate values equal to a voxel's image intensity in each of the image volumes and an origin defined as the multi-parametric mean of normal tissue image intensity values. Voxel positions were orthogonally projected onto a line defined by the origin and a pre-determined response vector. The voxels are subsequently classified as positive, negative or nil, according to whether projected positions along the response vector exceeded a threshold distance from the origin. The response vector was selected by identifying the direction in which the standard deviation of tumor image intensity values was maximally different between responding and non-responding patients within a training dataset. Voxel classifications were visualized via familiar three-class response maps and then the fraction of tumor voxels associated with each of the classes was investigated for predictive utility analogous to the original PRM method. Independent PRM and MPRM analyses of the contrast

Parametric investigations on the saturation intensity of Coumarin 102 for stimulated emission depletion application.

Science.gov (United States)

Qin, H-Y; Zhao, W-X; Zhao, W; Zhang, C; Feng, X-Q; Liu, S-P; Wang, K-G

2018-04-23

Stimulated emission depletion (STED) microscopy performed using continuous-wave (CW) lasers has been investigated and developed by Willig et al. (Nature Methods, 2007, 4(11):915) for nearly a decade. Kuang et al. (Review of Scientific Instruments, 2010, 81:053709) developed the CW STED microscopy technique with 405 nm excitation and 532 nm depletion beams. In their research, Coumarin 102 dye was adopted and was found to be depletable. In this study, a parametric investigation of the depletion of Coumarin 102 dye is carried out experimentally. The influence of the excitation and depletion beam intensities and dye concentrations on the depletion efficiency are studied in detail. The results indicate the following: (1) The highest depletion occurs for the 100 μM Coumarin 102 solution, with a 1.4 μW excitation beam and a 115.3 mW depletion beam. (2) The minimum saturation intensity (Is) of STED, that is 13 MW cm -2 , is observed when the Coumarin 102 solution concentration is 10 μM. (3) Is values calculated directly from the depletion power derived with the cross-sectional area due to the full-width-at-half-maximum (FWHM) of the depletion beam show poor accuracy, where Is may be overestimated. Thus, a correction factor for the cross-sectional area is proposed. We also find that Is is not exactly constant for a fixed excitation beam power and dye concentration. This trend indicates that the conventional suppression function η(x)=e- ln (2)ISTED(x)/Is derived from picosecond STED may cause errors in evaluating the depletion process in CW STED microscopy. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

Parametric influence of powerful radiation on plasma surface

International Nuclear Information System (INIS)

Kuklin, V.M.; Panchenko, I.P.; Chernousenko, V.M.

1989-01-01

A self-consistent set of equations that describes one-dimensional dynamics to develop the instability of long-wave intensive Langmuir wave is obtained and solved. The parametric instability influence on the character of absorption of the incident radiation energy is elucidated primarily. 40 refs.; 8 figs

Classification rates: non‐parametric verses parametric models using ...

African Journals Online (AJOL)

This research sought to establish if non parametric modeling achieves a higher correct classification ratio than a parametric model. The local likelihood technique was used to model fit the data sets. The same sets of data were modeled using parametric logit and the abilities of the two models to correctly predict the binary ...

Absolute parametric instability in a nonuniform plane plasma

Indian Academy of Sciences (India)

The paper reports an analysis of the effect of spatial plasma nonuniformity on absolute parametric instability (API) of electrostatic waves in magnetized plane waveguides subjected to an intense high-frequency (HF) electric field using the separation method. In this case the effect of strong static magnetic field is considered.

Probing the dynamics of dark energy with novel parametrizations

International Nuclear Information System (INIS)

Ma Jingzhe; Zhang Xin

2011-01-01

We point out that the CPL parametrization has a problem that the equation of state w(z) diverges in the far future, so that this model can only properly describe the past evolution but cannot depict the future evolution. To overcome such a difficulty, in this Letter we propose two novel parametrizations for dark energy, the logarithm form w(z)=w 0 +w 1 ((ln(2+z))/(1+z) -ln2) and the oscillating form w(z)=w 0 +w 1 ((sin(1+z))/(1+z) -sin(1)), successfully avoiding the future divergency problem in the CPL parametrization, and use them to probe the dynamics of dark energy in the whole evolutionary history. Our divergency-free parametrizations are proven to be very successful in exploring the dynamical evolution of dark energy and have powerful prediction capability for the ultimate fate of the universe. Constraining the CPL model and the new models with the current observational data, we show that the new models are more favored. The features and the predictions for the future evolution in the new models are discussed in detail.

Non-parametric system identification from non-linear stochastic response

DEFF Research Database (Denmark)

Rüdinger, Finn; Krenk, Steen

2001-01-01

An estimation method is proposed for identification of non-linear stiffness and damping of single-degree-of-freedom systems under stationary white noise excitation. Non-parametric estimates of the stiffness and damping along with an estimate of the white noise intensity are obtained by suitable...... of the energy at mean-level crossings, which yields the damping relative to white noise intensity. Finally, an estimate of the noise intensity is extracted by estimating the absolute damping from the autocovariance functions of a set of modified phase plane variables at different energy levels. The method...

Absolute parametric instability in a nonuniform plane plasma ...

Indian Academy of Sciences (India)

Abstract. The paper reports an analysis of the effect of spatial plasma nonuniformity on absolute parametric instability (API) of electrostatic waves in magnetized plane waveguides subjected to an intense high-frequency (HF) electric field using the separation method. In this case the effect of strong static magnetic field is ...

Pixel-based parametric source depth map for Cerenkov luminescence imaging

International Nuclear Information System (INIS)

Altabella, L.; Spinelli, A.E.; Boschi, F.

2016-01-01

Optical tomography represents a challenging problem in optical imaging because of the intrinsically ill-posed inverse problem due to photon diffusion. Cerenkov luminescence tomography (CLT) for optical photons produced in tissues by several radionuclides (i.e.: 32P, 18F, 90Y), has been investigated using both 3D multispectral approach and multiviews methods. Difficult in convergence of 3D algorithms can discourage to use this technique to have information of depth and intensity of source. For these reasons, we developed a faster 2D corrected approach based on multispectral acquisitions, to obtain source depth and its intensity using a pixel-based fitting of source intensity. Monte Carlo simulations and experimental data were used to develop and validate the method to obtain the parametric map of source depth. With this approach we obtain parametric source depth maps with a precision between 3% and 7% for MC simulation and 5–6% for experimental data. Using this method we are able to obtain reliable information about the source depth of Cerenkov luminescence with a simple and flexible procedure

Nonlinear dynamics of parametrically driven particles in a Φ6 potential

International Nuclear Information System (INIS)

Tchawoua, C; Siewe Siewe, M; Tchatchueng, S; Moukam Kakmeni, F M

2008-01-01

A general parametrically excited mechanical system is considered. Approximate solutions are determined by applying the method of multiple time scales. It is shown that only combination parametric resonance of the additive type is possible for the system examined. For this case, the existence and stability properties of the fixed points of the averaged equations corresponding to the nontrivial periodic solutions of the original system are investigated. Thus, emphasis is placed on understanding the chaotic behaviour of the extended Duffing oscillator in the Φ 6 potential under parametric excitation for a specific parameter choice. From the Melnikov-type technique, we obtain the conditions for the existence of homoclinic or heteroclinic bifurcation. Our analysis is carried out in the case of a triple well with a double hump which does not lead to unbounded motion; this analysis is complemented by numerical simulations from which we illustrate the fractality of the basins of attraction. The results show that the threshold amplitude of parametric excitation moves upwards as the parametric intensity increases. Numerical simulations including bifurcation diagrams, Lyapunov exponents, phase portraits and Poincaré maps are shown

Parametric wave penetration through an overdense plasma layer

International Nuclear Information System (INIS)

Gradov, O.M.; Suender, D.

1981-01-01

The nonlinear penetration of an electromagnetic wave through an overdense plasma layer due to the excitation of parametric instabilities is studied. The quasistatic h.f. surface wave and the ion-acoustic wave, both parametrically growing, generate a nonlinear current which also exist beyound the linear skin length of the incident electromagnetic wave. This current leads to an exponential amplification of the electromagnetic wave amplitude in the layer. The growth rate of this process depends on the overthreshold value of the external wave intensity and the thickness of the layer. The saturation level of the transmitted wave amplitude is estimated for the case, when the instabilities are stabilized by generation of ion-acoustic harmonics. (author)

A short form of the neonatal intensive care unit family needs inventory

Directory of Open Access Journals (Sweden)

Elisabete Alves

2016-02-01

Full Text Available ABSTRACT OBJECTIVE: The identification of parental needs in Neonatal Intensive Care Units is essential to design and implement family-centered care. This article aims to validate the Neonatal Intensive Care Units Family Needs Inventory for the Portuguese population, and to propose a Short Form. METHODS: A linguistic adaptation of the Neonatal Intensive Care Units Family Needs Inventory, a self-report scale with 56-items, was performed. The instrument was administered to 211 parents of infants hospitalized in all level III Neonatal Intensive Care Units in the North of Portugal, 15-22 days after admission (July of 2013-June of 2014. The number of items needed to achieve reliability close to 0.8 was calculated using by the Spearman-Brown formula. The global goodness of fit of the scale was evaluated using the comparative fit index. Construct validity was assessed through association of each dimension score with socio-demographic and obstetric characteristics. RESULTS: Exploratory factor analysis revealed two dimensions, one focused on parents' needs and another on the infant's needs. To compose the Short Form Inventory, items with ceiling effect were eliminated and 22 items were submitted to confirmatory analysis, which supported the existence of two dimensions (CFI = 0.925. The Short Form showed a high degree of reliability (alpha ≥ 0.76. Less educated and older parents more frequently attributed a significantly higher importance to parent-centered needs, while parents of multiples revealed a tendency to value infant-centered needs. CONCLUSIONS: The Short Form of the Neonatal Intensive Care Units Family Needs Inventory is a brief, simple, and valid instrument with a high degree of reliability. Further studies are needed to explore associations with practices of family-centered care.

Zero- vs. one-dimensional, parametric vs. non-parametric, and confidence interval vs. hypothesis testing procedures in one-dimensional biomechanical trajectory analysis.

Science.gov (United States)

Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

2015-05-01

Biomechanical processes are often manifested as one-dimensional (1D) trajectories. It has been shown that 1D confidence intervals (CIs) are biased when based on 0D statistical procedures, and the non-parametric 1D bootstrap CI has emerged in the Biomechanics literature as a viable solution. The primary purpose of this paper was to clarify that, for 1D biomechanics datasets, the distinction between 0D and 1D methods is much more important than the distinction between parametric and non-parametric procedures. A secondary purpose was to demonstrate that a parametric equivalent to the 1D bootstrap exists in the form of a random field theory (RFT) correction for multiple comparisons. To emphasize these points we analyzed six datasets consisting of force and kinematic trajectories in one-sample, paired, two-sample and regression designs. Results showed, first, that the 1D bootstrap and other 1D non-parametric CIs were qualitatively identical to RFT CIs, and all were very different from 0D CIs. Second, 1D parametric and 1D non-parametric hypothesis testing results were qualitatively identical for all six datasets. Last, we highlight the limitations of 1D CIs by demonstrating that they are complex, design-dependent, and thus non-generalizable. These results suggest that (i) analyses of 1D data based on 0D models of randomness are generally biased unless one explicitly identifies 0D variables before the experiment, and (ii) parametric and non-parametric 1D hypothesis testing provide an unambiguous framework for analysis when one׳s hypothesis explicitly or implicitly pertains to whole 1D trajectories. Copyright © 2015 Elsevier Ltd. All rights reserved.

Parametric instabilities in advanced gravitational wave detectors

International Nuclear Information System (INIS)

Gras, S; Zhao, C; Blair, D G; Ju, L

2010-01-01

As the LIGO interferometric gravitational wave detectors have finished gathering a large observational data set, an intense effort is underway to upgrade these observatories to improve their sensitivity by a factor of ∼10. High circulating power in the arm cavities is required, which leads to the possibility of parametric instability due to three-mode opto-acoustic resonant interactions between the carrier, transverse optical modes and acoustic modes. Here, we present detailed numerical analysis of parametric instability in a configuration that is similar to Advanced LIGO. After examining parametric instability for a single three-mode interaction in detail, we examine instability for the best and worst cases, as determined by the resonance condition of transverse modes in the power and signal recycling cavities. We find that, in the best case, the dual recycling detector is substantially less susceptible to instability than a single cavity, but its susceptibility is dependent on the signal recycling cavity design, and on tuning for narrow band operation. In all cases considered, the interferometer will experience parametric instability at full power operation, but the gain varies from 3 to 1000, and the number of unstable modes varies between 7 and 30 per test mass. The analysis focuses on understanding the detector complexity in relation to opto-acoustic interactions, on providing insights that can enable predictions of the detector response to transient disturbances, and of variations in thermal compensation conditions.

Relaxed damage threshold intensity conditions and nonlinear increase in the conversion efficiency of an optical parametric oscillator using a bi-directional pump geometry.

Science.gov (United States)

Norris, G; McConnell, G

2010-03-01

A novel bi-directional pump geometry that nonlinearly increases the nonlinear optical conversion efficiency of a synchronously pumped optical parametric oscillator (OPO) is reported. This bi-directional pumping method synchronizes the circulating signal pulse with two counter-propagating pump pulses within a linear OPO resonator. Through this pump scheme, an increase in nonlinear optical conversion efficiency of 22% was achieved at the signal wavelength, corresponding to a 95% overall increase in average power. Given an almost unchanged measured pulse duration of 260 fs under optimal performance conditions, this related to a signal wavelength peak power output of 18.8 kW, compared with 10 kW using the traditional single-pass geometry. In this study, a total effective peak intensity pump-field of 7.11 GW/cm(2) (corresponding to 3.55 GW/cm(2) from each pump beam) was applied to a 3 mm long periodically poled lithium niobate crystal, which had a damage threshold intensity of 4 GW/cm(2), without impairing crystal integrity. We therefore prove the application of this novel pump geometry provides opportunities for power-scaling of synchronously pumped OPO systems together with enhanced nonlinear conversion efficiency through relaxed damage threshold intensity conditions.

Parametrization of contrails in a comprehensive climate model

Energy Technology Data Exchange (ETDEWEB)

Ponater, M; Brinkop, S; Sausen, R; Schumann, U [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

1998-12-31

A contrail parametrization scheme for a general circulation model (GCM) is presented. Guidelines for its development were that it should be based on the thermodynamic theory of contrail formation and that it should be consistent with the cloud parametrization scheme of the GCM. Results of a six-year test integration indicate reasonable results concerning the spatial and temporal development of both contrail coverage and contrail optical properties. Hence, the scheme forms a promising basis for the quantitative estimation of the contrail climatic impact. (author) 9 refs.

Parametrization of contrails in a comprehensive climate model

Energy Technology Data Exchange (ETDEWEB)

Ponater, M.; Brinkop, S.; Sausen, R.; Schumann, U. [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

1997-12-31

A contrail parametrization scheme for a general circulation model (GCM) is presented. Guidelines for its development were that it should be based on the thermodynamic theory of contrail formation and that it should be consistent with the cloud parametrization scheme of the GCM. Results of a six-year test integration indicate reasonable results concerning the spatial and temporal development of both contrail coverage and contrail optical properties. Hence, the scheme forms a promising basis for the quantitative estimation of the contrail climatic impact. (author) 9 refs.

A parametric LTR solution for discrete-time systems

DEFF Research Database (Denmark)

Niemann, Hans Henrik; Jannerup, Ole Erik

1989-01-01

A parametric LTR (loop transfer recovery) solution for discrete-time compensators incorporating filtering observers which achieve exact recovery is presented for both minimum- and non-minimum-phase systems. First the recovery error, which defines the difference between the target loop transfer...... and the full loop transfer function, is manipulated into a general form involving the target loop transfer matrix and the fundamental recovery matrix. A parametric LTR solution based on the recovery matrix is developed. It is shown that the LQR/LTR (linear quadratic Gaussian/loop transfer recovery) solution...

Image sequence analysis in nuclear medicine: (1) Parametric imaging using statistical modelling

International Nuclear Information System (INIS)

Liehn, J.C.; Hannequin, P.; Valeyre, J.

1989-01-01

This is a review of parametric imaging methods on Nuclear Medicine. A Parametric Image is an image in which each pixel value is a function of the value of the same pixel of an image sequence. The Local Model Method is the fitting of each pixel time activity curve by a model which parameter values form the Parametric Images. The Global Model Method is the modelling of the changes between two images. It is applied to image comparison. For both methods, the different models, the identification criterion, the optimization methods and the statistical properties of the images are discussed. The analysis of one or more Parametric Images is performed using 1D or 2D histograms. The statistically significant Parametric Images, (Images of significant Variances, Amplitudes and Differences) are also proposed [fr

Multi-pulse orbits and chaotic dynamics in motion of parametrically excited viscoelastic moving belt

International Nuclear Information System (INIS)

Zhang Wei; Yao Minghui

2006-01-01

In this paper, the Shilnikov type multi-pulse orbits and chaotic dynamics of parametrically excited viscoelastic moving belt are studied in detail. Using Kelvin-type viscoelastic constitutive law, the equations of motion for viscoelastic moving belt with the external damping and parametric excitation are given. The four-dimensional averaged equation under the case of primary parametric resonance is obtained by directly using the method of multiple scales and Galerkin's approach to the partial differential governing equation of viscoelastic moving belt. From the averaged equations obtained here, the theory of normal form is used to give the explicit expressions of normal form with a double zero and a pair of pure imaginary eigenvalues. Based on normal form, the energy-phrase method is employed to analyze the global bifurcations and chaotic dynamics in parametrically excited viscoelastic moving belt. The global bifurcation analysis indicates that there exist the heteroclinic bifurcations and the Silnikov type multi-pulse homoclinic orbits in the averaged equation. The results obtained above mean the existence of the chaos for the Smale horseshoe sense in parametrically excited viscoelastic moving belt. The chaotic motions of viscoelastic moving belts are also found by using numerical simulation. A new phenomenon on the multi-pulse jumping orbits is observed from three-dimensional phase space

Parametric investigations of target normal sheath acceleration experiments

International Nuclear Information System (INIS)

Zani, Alessandro; Sgattoni, Andrea; Passoni, Matteo

2011-01-01

One of the most important challenges related to laser-driven ion acceleration research is to actively control some important ion beam features. This is a peculiar topic in the light of future possible technological applications. In the present work we make use of one theoretical model for target normal sheath acceleration in order to reproduce recent experimental parametric studies about maximum ion energy dependencies on laser parameters. The key role played by pulse energy and intensity is enlightened. Finally the effective dependence of maximum ion energy on intensity is evaluated using a combined theoretical approach, obtained by means of an analytical and a particle-in-cell numerical investigation.

Parametric investigations of target normal sheath acceleration experiments

Science.gov (United States)

Zani, Alessandro; Sgattoni, Andrea; Passoni, Matteo

2011-10-01

One of the most important challenges related to laser-driven ion acceleration research is to actively control some important ion beam features. This is a peculiar topic in the light of future possible technological applications. In the present work we make use of one theoretical model for target normal sheath acceleration in order to reproduce recent experimental parametric studies about maximum ion energy dependencies on laser parameters. The key role played by pulse energy and intensity is enlightened. Finally the effective dependence of maximum ion energy on intensity is evaluated using a combined theoretical approach, obtained by means of an analytical and a particle-in-cell numerical investigation.

Direct 4D reconstruction of parametric images incorporating anato-functional joint entropy.

Science.gov (United States)

Tang, Jing; Kuwabara, Hiroto; Wong, Dean F; Rahmim, Arman

2010-08-07

We developed an anatomy-guided 4D closed-form algorithm to directly reconstruct parametric images from projection data for (nearly) irreversible tracers. Conventional methods consist of individually reconstructing 2D/3D PET data, followed by graphical analysis on the sequence of reconstructed image frames. The proposed direct reconstruction approach maintains the simplicity and accuracy of the expectation-maximization (EM) algorithm by extending the system matrix to include the relation between the parametric images and the measured data. A closed-form solution was achieved using a different hidden complete-data formulation within the EM framework. Furthermore, the proposed method was extended to maximum a posterior reconstruction via incorporation of MR image information, taking the joint entropy between MR and parametric PET features as the prior. Using realistic simulated noisy [(11)C]-naltrindole PET and MR brain images/data, the quantitative performance of the proposed methods was investigated. Significant improvements in terms of noise versus bias performance were demonstrated when performing direct parametric reconstruction, and additionally upon extending the algorithm to its Bayesian counterpart using the MR-PET joint entropy measure.

Characterization of solar cells for space applications. Volume 6: Electrical characteristics of Spectrolab BSF, BSR, textured, 10 ohm-cm, 50 micron advanced OAST solar cells as a function of intensity, temperature, and irradiation

Science.gov (United States)

Anspaugh, B. E.; Downing, R. G.; Miyahira, T. F.; Weiss, R. S.

1979-01-01

Electrical parametric data are presented on BSF, BSR, textured 10 ohm cm, 50 micron advanced OAST cells in graphical and tabular form as functions of solar illumination intensity, temperature, and 1 MeV electron fluence.

A Range-Based Test for the Parametric Form of the Volatility in Diffusion Models

DEFF Research Database (Denmark)

Podolskij, Mark; Ziggel, Daniel

statistic. Under rather weak assumptions on the drift and volatility we prove weak convergence of the test statistic to a centered mixed Gaussian distribution. As a consequence we obtain a test, which is consistent for any fixed alternative. Moreover, we present a parametric bootstrap procedure which...

Correlations in photon-numbers and integrated intensities in parametric processes involving three optical fields

Czech Academy of Sciences Publication Activity Database

Peřina, Jan; Křepelka, Jaromír; Peřina ml., Jan; Bondani, M.; Allevi, A.; Andreoni, A.

2009-01-01

Roč. 53, č. 3 (2009), 373-382 ISSN 1434-6060 R&D Projects: GA AV ČR KAN301370701; GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : parametric process * three-mode state * sub-Poisson statistics * conditional measurement Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.420, year: 2009

Multi-parametric monitoring and assessment of high-intensity focused ultrasound (HIFU) boiling by harmonic motion imaging for focused ultrasound (HMIFU): an ex vivo feasibility study

International Nuclear Information System (INIS)

Hou, Gary Y; Marquet, Fabrice; Wang, Shutao; Konofagou, Elisa E

2014-01-01

Harmonic motion imaging for focused ultrasound (HMIFU) is a recently developed high-intensity focused ultrasound (HIFU) treatment monitoring method with feasibilities demonstrated in vitro and in vivo. Here, a multi-parametric study is performed to investigate both elastic and acoustics-independent viscoelastic tissue changes using the Harmonic Motion Imaging (HMI) displacement, axial compressive strain and change in relative phase shift during high energy HIFU treatment with tissue boiling. Forty three (n = 43) thermal lesions were formed in ex vivo canine liver specimens (n = 28). Two-dimensional (2D) transverse HMI displacement maps were also obtained before and after lesion formation. The same method was repeated in 10 s, 20 s and 30 s HIFU durations at three different acoustic powers of 8, 10, and 11 W, which were selected and verified as treatment parameters capable of inducing boiling using both thermocouple and passive cavitation detection (PCD) measurements. Although a steady decrease in the displacement, compressive strain, and relative change in the focal phase shift (Δϕ) were obtained in numerous cases, indicating an overall increase in relative stiffness, the study outcomes also showed that during boiling, a reverse lesion-to-background displacement contrast was detected, indicating potential change in tissue absorption, geometrical change and/or, mechanical gelatification or pulverization. Following treatment, corresponding 2D HMI displacement images of the thermal lesions also mapped consistent discrepancy in the lesion-to-background displacement contrast. Despite the expectedly chaotic changes in acoustic properties with boiling, the relative change in phase shift showed a consistent decrease, indicating its robustness to monitor biomechanical properties independent of the acoustic property changes throughout the HIFU treatment. In addition, the 2D HMI displacement images confirmed and indicated the increase in the thermal lesion size with

Method of development of the program of forming of parametrical drawings of details in the AutoCAD software product

Science.gov (United States)

Alshakova, E. L.

2017-01-01

The program in the AutoLISP language allows automatically to form parametrical drawings during the work in the AutoCAD software product. Students study development of programs on AutoLISP language with the use of the methodical complex containing methodical instructions in which real examples of creation of images and drawings are realized. Methodical instructions contain reference information necessary for the performance of the offered tasks. The method of step-by-step development of the program is the basis for training in programming on AutoLISP language: the program draws elements of the drawing of a detail by means of definitely created function which values of arguments register in that sequence in which AutoCAD gives out inquiries when performing the corresponding command in the editor. The process of the program design is reduced to the process of step-by-step formation of functions and sequence of their calls. The author considers the development of the AutoLISP program for the creation of parametrical drawings of details, the defined design, the user enters the dimensions of elements of details. These programs generate variants of tasks of the graphic works performed in educational process of "Engineering graphics", "Engineering and computer graphics" disciplines. Individual tasks allow to develop at students skills of independent work in reading and creation of drawings, as well as 3D modeling.

A new simple form of quark mixing matrix

Energy Technology Data Exchange (ETDEWEB)

Qin Nan [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Ma Boqiang, E-mail: mabq@pku.edu.c [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Center for High Energy Physics, Peking University, Beijing 100871 (China)

2011-01-10

Although different parametrizations of quark mixing matrix are mathematically equivalent, the consequences of experimental analysis may be distinct. Based on the triminimal expansion of Kobayashi-Maskawa matrix around the unit matrix, we propose a new simple parametrization. Compared with the Wolfenstein parametrization, we find that the new form is not only consistent with the original one in the hierarchical structure, but also more convenient for numerical analysis and measurement of the CP-violating phase. By discussing the relation between our new form and the unitarity boomerang, we point out that along with the unitarity boomerang, this new parametrization is useful in hunting for new physics.

A new simple form of quark mixing matrix

International Nuclear Information System (INIS)

Qin Nan; Ma Boqiang

2011-01-01

Although different parametrizations of quark mixing matrix are mathematically equivalent, the consequences of experimental analysis may be distinct. Based on the triminimal expansion of Kobayashi-Maskawa matrix around the unit matrix, we propose a new simple parametrization. Compared with the Wolfenstein parametrization, we find that the new form is not only consistent with the original one in the hierarchical structure, but also more convenient for numerical analysis and measurement of the CP-violating phase. By discussing the relation between our new form and the unitarity boomerang, we point out that along with the unitarity boomerang, this new parametrization is useful in hunting for new physics.

Parametric instabilities in inhomogeneous plasma

International Nuclear Information System (INIS)

Nicholson, D.R.

1975-01-01

The nonlinear coupling of three waves in a plasma is considered. One of the waves is assumed large and constant; its amplitude is the parameter of the parametric instability. The spatial-temporal evolution of the other two waves is treated theoretically, in one dimension, by analytic methods and by direct numerical integration of the basic equations. Various monotonic forms of inhomogeneity are considered; agreement with previous work is found and new results are established. Nonmonotonic inhomogeneities are considered, in the form of turbulence and, as a model problem, in the form of a simple sinusoidal modulation. Relatively small amounts of nonmonotonic inhomogeneity, in the presence of a linear density gradient, are found to destabilize the well-known convective saturation, absolute growth occurring instead. (U.S.)

Chaotic parametric soliton-like pulses in ferromagnetic-film active ring resonators

International Nuclear Information System (INIS)

Grishin, S. V.; Golova, T. M.; Morozova, M. A.; Romanenko, D. V.; Seleznev, E. P.; Sysoev, I. V.; Sharaevskii, Yu. P.

2015-01-01

The generation of quasi-periodic sequences of parametric soliton-like pulses in an active ring resonator with a ferromagnetic film via the three-wave parametric instability of a magnetostatic surface wave is studied theoretically and experimentally. These dissipative structures form in time due to the competition between the cubic nonlinearity caused by parametric coupling between spin waves and the time dispersion caused by the resonant cavity that is present in a self-oscillatory system. The development of dynamic chaos due to the parametric instability of a magnetostatic surface wave results in irregular behavior of a phase. However, this behavior does not break a quasi-periodic pulse sequence when the gain changes over a wide range. The generated soliton-like pulses have a chaotic nature, which is supported by the maximum Lyapunov exponent estimated from experimental time series

Parametric X-rays from a polycrystalline target

International Nuclear Information System (INIS)

Lobach, Ihar; Benediktovitch, Andrei; Feranchuk, Ilya; Lobko, Alexander

2015-01-01

Highlights: • X-ray radiation from relativistic electrons in a polycrystal is described. • Analytical results are found for two models of the polycrystal texture. • Characteristic number of emitted photons for real accelerator is 10 6 s −1 . • Intensity distribution at fixed frequency resembles a set of rings. • Radiation intensities in monocrystals and polycrystals are compared. - Abstract: A theoretical description of parametric X-ray radiation (PXR) from a nanocrystal powder target is presented in terms of the orientation distribution function (ODF). Two models of ODF resulting in the analytical solution for the PXR intensity distribution are used and the characteristic features of this distribution are considered. A promising estimate of the number of the emitted photons is obtained for the case of a nanodiamond powder target using the parameters of ASTA Facility at Fermilab. The PXR spectra from polycrystal and single crystal targets are compared. The application scenarios of PXR from nanocrystals are discussed.

Path integral quantization of parametrized field theory

International Nuclear Information System (INIS)

Varadarajan, Madhavan

2004-01-01

Free scalar field theory on a flat spacetime can be cast into a generally covariant form known as parametrized field theory in which the action is a functional of the scalar field as well as the embedding variables which describe arbitrary, in general curved, foliations of the flat spacetime. We construct the path integral quantization of parametrized field theory in order to analyze issues at the interface of quantum field theory and general covariance in a path integral context. We show that the measure in the Lorentzian path integral is nontrivial and is the analog of the Fradkin-Vilkovisky measure for quantum gravity. We construct Euclidean functional integrals in the generally covariant setting of parametrized field theory using key ideas of Schleich and show that our constructions imply the existence of nonstandard 'Wick rotations' of the standard free scalar field two-point function. We develop a framework to study the problem of time through computations of scalar field two-point functions. We illustrate our ideas through explicit computation for a time independent (1+1)-dimensional foliation. Although the problem of time seems to be absent in this simple example, the general case is still open. We discuss our results in the contexts of the path integral formulation of quantum gravity and the canonical quantization of parametrized field theory

Parametric Resonance in Dynamical Systems

CERN Document Server

Nijmeijer, Henk

2012-01-01

Parametric Resonance in Dynamical Systems discusses the phenomenon of parametric resonance and its occurrence in mechanical systems,vehicles, motorcycles, aircraft and marine craft, and micro-electro-mechanical systems. The contributors provide an introduction to the root causes of this phenomenon and its mathematical equivalent, the Mathieu-Hill equation. Also included is a discussion of how parametric resonance occurs on ships and offshore systems and its frequency in mechanical and electrical systems. This book also: Presents the theory and principles behind parametric resonance Provides a unique collection of the different fields where parametric resonance appears including ships and offshore structures, automotive vehicles and mechanical systems Discusses ways to combat, cope with and prevent parametric resonance including passive design measures and active control methods Parametric Resonance in Dynamical Systems is ideal for researchers and mechanical engineers working in application fields such as MEM...

Parametric Cherenkov radiation (development of idea)

International Nuclear Information System (INIS)

Buts, V.A.

2004-01-01

Some physical results of researches about charged particles radiation in mediums with a periodic heterogeneity and in periodic potential are reported. The development of ideas Parametric Cherenkov Radiation has shown, that in mediums, which have even a weak degree of a periodic heterogeneity of an permittivity or potential, the nonrelativistic oscillators can radiated as relativistic. They effectively radiate the high numbers of harmonics. In particular, in the carried out experiments the ultra-violet radiation was excited at action on a crystal of intensive ten-centimetric radiation. These results give the reasons to hope for making of nonrelativistic lasers on free electrons

Four-photon parametric mixing and interaction between filaments

Energy Technology Data Exchange (ETDEWEB)

Georgieva, D. A. [Faculty of Applied Mathematics and Computer Science, Technical University of Sofia, 8 Kliment Ohridski Blvd., 1000 Sofia (Bulgaria); Kovachev, L. M. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradcko Chaussee Blvd.,1784 Sofia (Bulgaria)

2014-11-12

Recently energy exchange between two filaments crossing at small angle and with power slightly above the critical for self-focusing P{sub cr} was experimentally demonstrated. In this paper we present a model describing the process of this transfer through degenerate four-photon parametric mixing. Our model confirms the experimental results that the direction of energy exchange depends on the relative transverse velocity (incident angle), laser intensity and initial distance between the pulses (relative initial phase)

Non-parametric Tuning of PID Controllers A Modified Relay-Feedback-Test Approach

CERN Document Server

Boiko, Igor

2013-01-01

The relay feedback test (RFT) has become a popular and efficient  tool used in process identification and automatic controller tuning. Non-parametric Tuning of PID Controllers couples new modifications of classical RFT with application-specific optimal tuning rules to form a non-parametric method of test-and-tuning. Test and tuning are coordinated through a set of common parameters so that a PID controller can obtain the desired gain or phase margins in a system exactly, even with unknown process dynamics. The concept of process-specific optimal tuning rules in the nonparametric setup, with corresponding tuning rules for flow, level pressure, and temperature control loops is presented in the text.   Common problems of tuning accuracy based on parametric and non-parametric approaches are addressed. In addition, the text treats the parametric approach to tuning based on the modified RFT approach and the exact model of oscillations in the system under test using the locus of a perturbedrelay system (LPRS) meth...

Parametric level correlations in random-matrix models

International Nuclear Information System (INIS)

Weidenmueller, Hans A

2005-01-01

We show that parametric level correlations in random-matrix theories are closely related to a breaking of the symmetry between the advanced and the retarded Green functions. The form of the parametric level correlation function is the same as for the disordered case considered earlier by Simons and Altshuler and is given by the graded trace of the commutator of the saddle-point solution with the particular matrix that describes the symmetry breaking in the actual case of interest. The strength factor differs from the case of disorder. It is determined solely by the Goldstone mode. It is essentially given by the number of levels that are strongly mixed as the external parameter changes. The factor can easily be estimated in applications

A non-parametric Bayesian approach to decompounding from high frequency data

NARCIS (Netherlands)

Gugushvili, Shota; van der Meulen, F.H.; Spreij, Peter

2016-01-01

Given a sample from a discretely observed compound Poisson process, we consider non-parametric estimation of the density f0 of its jump sizes, as well as of its intensity λ0. We take a Bayesian approach to the problem and specify the prior on f0 as the Dirichlet location mixture of normal densities.

Using Spline Regression in Semi-Parametric Stochastic Frontier Analysis: An Application to Polish Dairy Farms

DEFF Research Database (Denmark)

Czekaj, Tomasz Gerard; Henningsen, Arne

of specifying an unsuitable functional form and thus, model misspecification and biased parameter estimates. Given these problems of the DEA and the SFA, Fan, Li and Weersink (1996) proposed a semi-parametric stochastic frontier model that estimates the production function (frontier) by non......), Kumbhakar et al. (2007), and Henningsen and Kumbhakar (2009). The aim of this paper and its main contribution to the existing literature is the estimation semi-parametric stochastic frontier models using a different non-parametric estimation technique: spline regression (Ma et al. 2011). We apply...... efficiency of Polish dairy farms contributes to the insight into this dynamic process. Furthermore, we compare and evaluate the results of this spline-based semi-parametric stochastic frontier model with results of other semi-parametric stochastic frontier models and of traditional parametric stochastic...

Parametric motivation bases of floranimic nomination

Directory of Open Access Journals (Sweden)

Olga P. Ryabko

2016-09-01

Full Text Available The period of further development in the cognitive theory of nomination has been extensive in recent years. Our research has been concentrated on the formation of conceptual foundations in cognitive theory of flora nomination. The macrofield of flora namings embraces three microfields: parametric, pragmatic and locative-temporal ones. They determine motivation processes in cognitive theory of flora nomination, i.e., the presentation of systematic qualities in flora namings in the English language. The description and characterization of such qualities presupposes the existence of their taxonomic organization and methodology criteria, both general and practical ones. Flora namings on the phenomenological level are considered to be the products of naöve-cognitive consciousness of language speakers. They are determined, from the one hand, by the external perceptive adaptations (parametric nomination and, from the other hand, by practical needs (pure pragmatic nomination and local-temporal nomination. In this article we have concentrated on the complex parametric motivated basis of flora nomination. It is presented by a number of qualities, firstly, by dominative qualities («form», «appearance and manner of growth», «color», secondly, by peripheral qualities («odour», «taste», «size» and, finally, by minor qualities («sound», «weight», «genger». In the structure of complex parametric nomination the only one conerete qualitative element from the whole combination of qualities becomes the leading one. The cultural-archetypal dominant element determines. In each concrete situation, the choice of preferable prototypal motivated quality.

Statistical dynamics of parametrically perturbed sine-square map

Indian Academy of Sciences (India)

Abstract. We discuss the emergence and destruction of complex, critical and completely chaotic attractors in a nonlinear system when subjected to a small parametric perturba- tion in trigonometric, hyperbolic or noise function forms. For this purpose, a hybrid optical bistable system, which is a nonlinear physical system, has ...

Efficiency Analysis of German Electricity Distribution Utilities : Non-Parametric and Parametric Tests

OpenAIRE

von Hirschhausen, Christian R.; Cullmann, Astrid

2005-01-01

Abstract This paper applies parametric and non-parametric and parametric tests to assess the efficiency of electricity distribution companies in Germany. We address traditional issues in electricity sector benchmarking, such as the role of scale effects and optimal utility size, as well as new evidence specific to the situation in Germany. We use labour, capital, and peak load capacity as inputs, and units sold and the number of customers as output. The data cover 307 (out of 553) ...

Parametric spatiotemporal oscillation in reaction-diffusion systems.

Science.gov (United States)

Ghosh, Shyamolina; Ray, Deb Shankar

2016-03-01

We consider a reaction-diffusion system in a homogeneous stable steady state. On perturbation by a time-dependent sinusoidal forcing of a suitable scaling parameter the system exhibits parametric spatiotemporal instability beyond a critical threshold frequency. We have formulated a general scheme to calculate the threshold condition for oscillation and the range of unstable spatial modes lying within a V-shaped region reminiscent of Arnold's tongue. Full numerical simulations show that depending on the specificity of nonlinearity of the models, the instability may result in time-periodic stationary patterns in the form of standing clusters or spatially localized breathing patterns with characteristic wavelengths. Our theoretical analysis of the parametric oscillation in reaction-diffusion system is corroborated by full numerical simulation of two well-known chemical dynamical models: chlorite-iodine-malonic acid and Briggs-Rauscher reactions.

Parametrizations in scalar-tensor theories of gravity and the limit of general relativity

International Nuclear Information System (INIS)

Järv, L; Kuusk, P; Saal, M; Vilson, O

2014-01-01

We consider a general scalar-tensor theory of gravity and review briefly different forms it can be presented (different conformal frames and scalar field parametrizations). We investigate the conditions under which its field equations and the parametrized post-Newtonian parameters coincide with those of general relativity. We demonstrate that these so-called limits of general relativity are independent of the parametrization of the scalar field, although the transformation between scalar fields may be singular at the corresponding value of the scalar field. In particular, the limit of general relativity can equivalently be determined and investigated in the commonly used Jordan and Einstein frames.

APPROXIMATION OF FREE-FORM CURVE – AIRFOIL SHAPE

Directory of Open Access Journals (Sweden)

CHONG PERK LIN

2013-12-01

Full Text Available Approximation of free-form shape is essential in numerous engineering applications, particularly in automotive and aircraft industries. Commercial CAD software for the approximation of free-form shape is based almost exclusively on parametric polynomial and rational parametric polynomial. The parametric curve is defined by vector function of one independent variable R(u = (x(u, y(u, z(u, where 0≤u≤1. Bézier representation is one of the parametric functions, which is widely used in the approximating of free-form shape. Given a string of points with the assumption of sufficiently dense to characterise airfoil shape, it is desirable to approximate the shape with Bézier representation. The expectation is that the representation function is close to the shape within an acceptable working tolerance. In this paper, the aim is to explore the use of manual and automated methods for approximating section curve of airfoil with Bézier representation.

Measurements of parametric instability near the critical density and the resultant electron heating: Final report

International Nuclear Information System (INIS)

Mizuno, K.; De Groot, J.S.; Seka, W.

1986-01-01

Detailed studies of the ion acoustic parametric decay instability have been made. Theoretical and particle simulation results indicate these instabilities are important in long scale length plasma irradiated by moderate intensity laser light (10'' ≤ Iλ 2 /T/sub e/ (W/cm 2 ) (μm 2 )/(keV) ≤ 5 x 10 14 ). Laser light (λ 0 ≅ 1/2 μm) is focused onto a CH target. The parametric decay instability has been measured by detecting the emission spectrum at frequencies near 2ω 0 . The experimental results clearly indicate that this parametric instability is important for short wavelength (1/2 μm) laser light irradiation. The threshold of the parametric instability (λ 0 = 1/2 μm) was only slightly higher than that of 1 μm laser case. The measured wavelength shift of the Stokes component (λ 0 = 1/2 μm) compared very well with the 1 μm laser results

Experimental demonstration of spatially coherent beam combining using optical parametric amplification.

Science.gov (United States)

Kurita, Takashi; Sueda, Keiichi; Tsubakimoto, Koji; Miyanaga, Noriaki

2010-07-05

We experimentally demonstrated coherent beam combining using optical parametric amplification with a nonlinear crystal pumped by random-phased multiple-beam array of the second harmonic of a Nd:YAG laser at 10-Hz repetition rate. In the proof-of-principle experiment, the phase jump between two pump beams was precisely controlled by a motorized actuator. For the demonstration of multiple-beam combining a random phase plate was used to create random-phased beamlets as a pump pulse. Far-field patterns of the pump, the signal, and the idler indicated that the spatially coherent signal beams were obtained on both cases. This approach allows scaling of the intensity of optical parametric chirped pulse amplification up to the exa-watt level while maintaining diffraction-limited beam quality.

A convenient analytical form for the triton wave function

International Nuclear Information System (INIS)

Hajduk, C.; Green, A.M.; Sainio, M.E.

1979-01-01

The triton wave function obtained by solving the Faddeev equations with the Reid soft core potential is parametrized in a symmetrized cluster form. As a test the 3 He charge form factor is calculated for the exact and the parametrized wave functions and reasonable agreement between the two is found. (author)

Assessing pupil and school performance by non-parametric and parametric techniques

NARCIS (Netherlands)

de Witte, K.; Thanassoulis, E.; Simpson, G.; Battisti, G.; Charlesworth-May, A.

2010-01-01

This paper discusses the use of the non-parametric free disposal hull (FDH) and the parametric multi-level model (MLM) as alternative methods for measuring pupil and school attainment where hierarchical structured data are available. Using robust FDH estimates, we show how to decompose the overall

MRI intensity inhomogeneity correction by combining intensity and spatial information

International Nuclear Information System (INIS)

Vovk, Uros; Pernus, Franjo; Likar, Bostjan

2004-01-01

We propose a novel fully automated method for retrospective correction of intensity inhomogeneity, which is an undesired phenomenon in many automatic image analysis tasks, especially if quantitative analysis is the final goal. Besides most commonly used intensity features, additional spatial image features are incorporated to improve inhomogeneity correction and to make it more dynamic, so that local intensity variations can be corrected more efficiently. The proposed method is a four-step iterative procedure in which a non-parametric inhomogeneity correction is conducted. First, the probability distribution of image intensities and corresponding second derivatives is obtained. Second, intensity correction forces, condensing the probability distribution along the intensity feature, are computed for each voxel. Third, the inhomogeneity correction field is estimated by regularization of all voxel forces, and fourth, the corresponding partial inhomogeneity correction is performed. The degree of inhomogeneity correction dynamics is determined by the size of regularization kernel. The method was qualitatively and quantitatively evaluated on simulated and real MR brain images. The obtained results show that the proposed method does not corrupt inhomogeneity-free images and successfully corrects intensity inhomogeneity artefacts even if these are more dynamic

Active Control of Parametric Vibrations in Coupled Rotor-Blade Systems

DEFF Research Database (Denmark)

Christensen, Rene Hardam; Santos, Ilmar

2003-01-01

of modes. The designed control scheme is applied to a coupled rotor-blade system and dynamic responses are numerically evaluated. Such responses show that the vibrations are efficiently reduced. Frequency response diagrams demonstrate that both basis and parametric vibration modes are significantly...... the model becomes periodic-variant. In order to reduce basis as well as parametric vibrations by means of active control in such systems a time-variant control strategy has to be adopted. This paper presents a methodology for designing an active controller to reduce vibrations in a coupled rotor......-blade system. The main aim is to control blade as well as hub vibrations in such a system by means of active control with focus on reducing the parametric vibration. A periodic state feedback controller is designed by transforming the system into a linear time-invariant form. Using this a controller...

Towards Stabilizing Parametric Active Contours

DEFF Research Database (Denmark)

Liu, Jinchao; Fan, Zhun; Olsen, Søren Ingvor

2014-01-01

Numerical instability often occurs in evolving of parametric active contours. This is mainly due to the undesired change of parametrization during evolution. In this paper, we propose a new tangential diffusion term to compensate this undesired change. As a result, the parametrization will converge...

Consistency of parametric registration in serial MRI studies of brain tumor progression

International Nuclear Information System (INIS)

Mang, Andreas; Buzug, Thorsten M.; Schnabel, Julia A.; Crum, William R.; Modat, Marc; Ourselin, Sebastien; Hawkes, David J.; Camara-Rey, Oscar; Palm, Christoph; Caseiras, Gisele Brasil; Jaeger, H.R.

2008-01-01

The consistency of parametric registration in multi-temporal magnetic resonance (MR) imaging studies was evaluated. Serial MRI scans of adult patients with a brain tumor (glioma) were aligned by parametric registration. The performance of low-order spatial alignment (6/9/12 degrees of freedom) of different 3D serial MR-weighted images is evaluated. A registration protocol for the alignment of all images to one reference coordinate system at baseline is presented. Registration results were evaluated for both, multimodal intra-timepoint and mono-modal multi-temporal registration. The latter case might present a challenge to automatic intensity-based registration algorithms due to ill-defined correspondences. The performance of our algorithm was assessed by testing the inverse registration consistency. Four different similarity measures were evaluated to assess consistency. Careful visual inspection suggests that images are well aligned, but their consistency may be imperfect. Sub-voxel inconsistency within the brain was found for allsimilarity measures used for parametric multi-temporal registration. T1-weighted images were most reliable for establishing spatial correspondence between different timepoints. The parametric registration algorithm is feasible for use in this application. The sub-voxel resolution mean displacement error of registration transformations demonstrates that the algorithm converges to an almost identical solution for forward and reverse registration. (orig.)

Non-classical Signature of Parametric Fluorescence and its Application in Metrology

Directory of Open Access Journals (Sweden)

Hamar M.

2014-08-01

Full Text Available The article provides a short theoretical background of what the non-classical light means. We applied the criterion for the existence of non-classical effects derived by C.T. Lee on parametric fluorescence. The criterion was originally derived for the study of two light beams with one mode per beam. We checked if the criterion is still working for two multimode beams of parametric down-conversion through numerical simulations. The theoretical results were tested by measurement of photon number statistics of twin beams emitted by nonlinear BBO crystal pumped by intense femtoseconds UV pulse. We used ICCD camera as the detector of photons in both beams. It appears that the criterion can be used for the measurement of the quantum efficiencies of the ICCD cameras.

Parametric Bayesian Estimation of Differential Entropy and Relative Entropy

OpenAIRE

Gupta; Srivastava

2010-01-01

Given iid samples drawn from a distribution with known parametric form, we propose the minimization of expected Bregman divergence to form Bayesian estimates of differential entropy and relative entropy, and derive such estimators for the uniform, Gaussian, Wishart, and inverse Wishart distributions. Additionally, formulas are given for a log gamma Bregman divergence and the differential entropy and relative entropy for the Wishart and inverse Wishart. The results, as always with Bayesian est...

Parametric Level Statistics in Random Matrix Theory: Exact Solution

International Nuclear Information System (INIS)

Kanzieper, E.

1999-01-01

During recent several years, the theory of non-Gaussian random matrix ensembles has experienced a sound progress motivated by new ideas in quantum chromodynamics (QCD) and mesoscopic physics. Invariant non-Gaussian random matrix models appear to describe universal features of low-energy part of the spectrum of Dirac operator in QCD, and electron level statistics in normal conducting-superconducting hybrid structures. They also serve as a basis for constructing the toy models of universal spectral statistics expected at the edge of the metal-insulator transition. While conventional spectral statistics has received a detailed study in the context of RMT, quite a bit is known about parametric level statistics in non-Gaussian random matrix models. In this communication we report about exact solution to the problem of parametric level statistics in unitary invariant, U(N), non-Gaussian ensembles of N x N Hermitian random matrices with either soft or strong level confinement. The solution is formulated within the framework of the orthogonal polynomial technique and is shown to depend on both the unfolded two-point scalar kernel and the level confinement through a double integral transformation which, in turn, provides a constructive tool for description of parametric level correlations in non-Gaussian RMT. In the case of soft level confinement, the formalism developed is potentially applicable to a study of parametric level statistics in an important class of random matrix models with finite level compressibility expected to describe a disorder-induced metal-insulator transition. In random matrix ensembles with strong level confinement, the solution presented takes a particular simple form in the thermodynamic limit: In this case, a new intriguing connection relation between the parametric level statistics and the scalar two-point kernel of an unperturbed ensemble is demonstrated to emerge. Extension of the results obtained to higher-order parametric level statistics is

New parametrization for the scale dependent growth function in general relativity

International Nuclear Information System (INIS)

Dent, James B.; Dutta, Sourish; Perivolaropoulos, Leandros

2009-01-01

We study the scale-dependent evolution of the growth function δ(a,k) of cosmological perturbations in dark energy models based on general relativity. This scale dependence is more prominent on cosmological scales of 100h -1 Mpc or larger. We derive a new scale-dependent parametrization which generalizes the well-known Newtonian approximation result f 0 (a)≡(dlnδ 0 /dlna)=Ω(a) γ (γ=(6/11) for ΛCDM) which is a good approximation on scales less than 50h -1 Mpc. Our generalized parametrization is of the form f(a)=(f 0 (a)/1+ξ(a,k)), where ξ(a,k)=(3H 0 2 Ω 0m )/(ak 2 ). We demonstrate that this parametrization fits the exact result of a full general relativistic evaluation of the growth function up to horizon scales for both ΛCDM and dynamical dark energy. In contrast, the scale independent parametrization does not provide a good fit on scales beyond 5% of the horizon scale (k≅0.01h -1 Mpc).

Parametrization of the Richardson weather generator within the European Union

NARCIS (Netherlands)

Voet, van der P.; Kramer, K.; Diepen, van C.A.

1996-01-01

The Richardson model for mathematically generating daily weather data was parametrized. Thirty years' time-series of the 355 main meteorological stations in the European Union formed the database. Model parameters were derived from both observed weather station data and interpolated weather data on

Compact and intense parametric x-ray radiation source based on a linear accelerator with cryogenic accelerating and decelerating copper structures

Science.gov (United States)

Hyun, J.; Satoh, M.; Yoshida, M.; Sakai, T.; Hayakawa, Y.; Tanaka, T.; Hayakawa, K.; Sato, I.; Endo, K.

2018-01-01

This paper describes a proposal for a compact x-ray source based on parametric x-ray radiation (PXR). The PXR, which is produced when a single crystal is bombarded with relativistic electrons, has good monochromaticity and spatial coherence, and is expected to be well suited for imaging of low-Z materials and medical application. The proposed system employs a pair of copper accelerating structures which are operated at a cryogenic temperature of 20 K and arranged to form a resonant ring configuration. The electron beam is once accelerated up to 75 MeV in one of the structures, being decelerated down to lower than 7 MeV in the other structure after generating PXR at a single crystal, and then dumped. The expected x-ray yield is 1 09 photons /s at a center energy of 15 keV or higher.

STATCAT, Statistical Analysis of Parametric and Non-Parametric Data

International Nuclear Information System (INIS)

David, Hugh

1990-01-01

1 - Description of program or function: A suite of 26 programs designed to facilitate the appropriate statistical analysis and data handling of parametric and non-parametric data, using classical and modern univariate and multivariate methods. 2 - Method of solution: Data is read entry by entry, using a choice of input formats, and the resultant data bank is checked for out-of- range, rare, extreme or missing data. The completed STATCAT data bank can be treated by a variety of descriptive and inferential statistical methods, and modified, using other standard programs as required

Stable integrated hyper-parametric oscillator based on coupled optical microcavities.

Science.gov (United States)

Armaroli, Andrea; Feron, Patrice; Dumeige, Yannick

2015-12-01

We propose a flexible scheme based on three coupled optical microcavities that permits us to achieve stable oscillations in the microwave range, the frequency of which depends only on the cavity coupling rates. We find that the different dynamical regimes (soft and hard excitation) affect the oscillation intensity, but not their periods. This configuration may permit us to implement compact hyper-parametric sources on an integrated optical circuit with interesting applications in communications, sensing, and metrology.

A model of parametric X-ray radiation for application to diagnostic radiology

International Nuclear Information System (INIS)

Di Domenico, G.; Cardarelli, P.; Gambaccini, M.; Marziani, M.; Taibi, A.; Comandini, A.

2011-01-01

Parametric X-ray Radiation (PXR) is well known as an intense, tunable and quasi-monochromatic X-ray source. From the very first work of Ter-Mikaelian, who proposed the interaction phenomenon for Parametric X-rays many theoretical and experimental studies have investigated the characteristics of such a novel X-ray source. Within the framework of classical electrodynamics, we have thoroughly studied the physical implications of electrons moving through a medium at relativistic speed and then developed an analytical model of X-ray diffraction based on the PXR phenomenon. The model has been used to obtain information on the characteristics of PXR diffracted beam in terms of X-ray intensity, energy spectrum and angular distribution. Several crystals have been studied both in Bragg and Laue geometry and their relative yield has been compared. Preliminary results on the diagnostic potential of PXR have shown that, at a distance from the crystal which produces a size of the X-ray field useful for an imaging application, the photon yield of PXR is higher than that produced by a conventional X-ray tube, provided that a similar electron current is available.

Conformally parametrized surfaces associated with CPN-1 sigma models

International Nuclear Information System (INIS)

Grundland, A M; Hereman, W A; Yurdusen, I-dot

2008-01-01

Two-dimensional parametrized surfaces immersed in the su(N) algebra are investigated. The focus is on surfaces parametrized by solutions of the equations for the CP N-1 sigma model. The Lie-point symmetries of the CP N-1 model are computed for arbitrary N. The Weierstrass formula for immersion is determined and an explicit formula for a moving frame on a surface is constructed. This allows us to determine the structural equations and geometrical properties of surfaces in R N 2 -1 . The fundamental forms, Gaussian and mean curvatures, Willmore functional and topological charge of surfaces are given explicitly in terms of any holomorphic solution of the CP 2 model. The approach is illustrated through several examples, including surfaces immersed in low-dimensional su(N) algebras

Tokamak transmutation of (nuclear) waste (TTW): Parametric studies

International Nuclear Information System (INIS)

Cheng, E.T.; Krakowski, R.A.; Peng, Y.K.M.

1994-01-01

Radioactive waste generated as part of the commercial-power and defense nuclear programs can be either stored or transmuted. The latter treatment requires a capital-intensive neutron source and is reserved for particularly hazardous and long-lived actinide and fission-product waste. A comparative description of fusion-based transmutation is made on the basis of rudimentary estimates of ergonic performance and transmutation capacities versus inventories for both ultra-low-aspect-ratio (spherical torus, ST) and conversional (aspect-ratio) tokamak fusion-power-core drivers. The parametric systems studies reported herein provides a preamble to more-detailed, cost-based systems analyses

Motivations of parametric studies

International Nuclear Information System (INIS)

Birac, C.

1988-01-01

The paper concerns the motivations of parametric studies in connection with the Programme for the Inspection of Steel Components PISC II. The objective of the PISC II exercise is to evaluate the effectiveness of current and advanced NDT techniques for inspection of reactor pressure vessel components. The parametric studies were initiated to determine the influence of some parameters on defect detection and dimensioning, and to increase the technical bases of the Round Robin Tests. A description is given of the content of the parametric studies including:- the effect of the defects' characteristics, the effect of equipment characteristics, the effect of cladding, and possible use of electromagnetic techniques. (U.K.)

Parametrically Guided Generalized Additive Models with Application to Mergers and Acquisitions Data.

Science.gov (United States)

Fan, Jianqing; Maity, Arnab; Wang, Yihui; Wu, Yichao

2013-01-01

Generalized nonparametric additive models present a flexible way to evaluate the effects of several covariates on a general outcome of interest via a link function. In this modeling framework, one assumes that the effect of each of the covariates is nonparametric and additive. However, in practice, often there is prior information available about the shape of the regression functions, possibly from pilot studies or exploratory analysis. In this paper, we consider such situations and propose an estimation procedure where the prior information is used as a parametric guide to fit the additive model. Specifically, we first posit a parametric family for each of the regression functions using the prior information (parametric guides). After removing these parametric trends, we then estimate the remainder of the nonparametric functions using a nonparametric generalized additive model, and form the final estimates by adding back the parametric trend. We investigate the asymptotic properties of the estimates and show that when a good guide is chosen, the asymptotic variance of the estimates can be reduced significantly while keeping the asymptotic variance same as the unguided estimator. We observe the performance of our method via a simulation study and demonstrate our method by applying to a real data set on mergers and acquisitions.

Parametric decay of plasma waves near the upper-hybrid resonance

Science.gov (United States)

Dodin, I. Y.; Arefiev, A. V.

2017-10-01

An intense X wave propagating perpendicularly to dc magnetic field is unstable with respect to a parametric decay into an electron Bernstein wave and a lower-hybrid wave. A modified theory of this effect is proposed that extends to the high-intensity regime, where the instability rate γ ceases to be a linear function of the incident-wave amplitude. An explicit formula for γ is derived and expressed in terms of cold-plasma parameters. Theory predictions are in reasonable agreement with the results of the particle-in-cell simulations reported in Ref.. The work was supported by the U.S. DOE through Contract No. DE-AC02-09CH11466 and by the U.S. DOE-NNSA Cooperative Agreement No. DE-NA0002008.

Investigation of the Effects of High-Intensity, Intermittent Exercise and Unanticipation on Trunk and Lower Limb Biomechanics During a Side-Cutting Maneuver Using Statistical Parametric Mapping.

Science.gov (United States)

Whyte, Enda F; Richter, Chris; OʼConnor, Siobhan; Moran, Kieran A

2018-06-01

Whyte, EF, Richter, C, O'Connor, S, and Moran, KA. Investigation of the effects of high-intensity, intermittent exercise and unanticipation on trunk and lower limb biomechanics during a side-cutting maneuver using statistical parametric mapping. J Strength Cond Res 32(6): 1583-1593, 2018-Anterior cruciate ligament (ACL) injuries frequently occur during side-cutting maneuvers when fatigued or reacting to the sporting environment. Trunk and hip biomechanics are proposed to influence ACL loading during these activities. However, the effects of fatigue and unanticipation on the biomechanics of the kinetic chain may be limited by traditional discrete point analysis. We recruited 28 male, varsity, Gaelic footballers (21.7 ± 2.2 years; 178.7 ± 14.6 m; 81.8 ± 11.4 kg) to perform anticipated and unanticipated side-cutting maneuvers before and after a high-intensity, intermittent exercise protocol (HIIP). Statistical parametric mapping (repeated-measures analysis of varience) identified differences in phases of trunk and stance leg biomechanics during weight acceptance. Unanticipation resulted in less trunk flexion (p < 0.001) and greater side flexion away from the direction of cut (p < 0.001). This led to smaller (internal) knee flexor and greater (internal) knee extensor (p = 0.002-0.007), hip adductor (p = 0.005), and hip external rotator (p = 0.007) moments. The HIIP resulted in increased trunk flexion (p < 0.001) and side flexion away from the direction of cut (p = 0.038), resulting in smaller (internal) knee extensor moments (p = 0.006). One interaction effect was noted demonstrating greater hip extensor moments in the unanticipated condition post-HIIP (p = 0.025). Results demonstrate that unanticipation resulted in trunk kinematics considered an ACL injury risk factor. A subsequent increase in frontal and transverse plane hip loading and sagittal plane knee loading was observed, which may increase ACL strain. Conversely, HIIP-induced trunk kinematic alterations

Planar Parametrization in Isogeometric Analysis

DEFF Research Database (Denmark)

Gravesen, Jens; Evgrafov, Anton; Nguyen, Dang-Manh

2012-01-01

Before isogeometric analysis can be applied to solving a partial differential equation posed over some physical domain, one needs to construct a valid parametrization of the geometry. The accuracy of the analysis is affected by the quality of the parametrization. The challenge of computing...... and maintaining a valid geometry parametrization is particularly relevant in applications of isogemetric analysis to shape optimization, where the geometry varies from one optimization iteration to another. We propose a general framework for handling the geometry parametrization in isogeometric analysis and shape...... are suitable for our framework. The non-linear methods we consider are based on solving a constrained optimization problem numerically, and are divided into two classes, geometry-oriented methods and analysis-oriented methods. Their performance is illustrated through a few numerical examples....

Neutron charge radius and the neutron electric form factor

International Nuclear Information System (INIS)

Gentile, T. R.; Crawford, C. B.

2011-01-01

For nearly forty years, the Galster parametrization has been employed to fit existing data for the neutron electric form factor, G E n , vs the square of the four-momentum transfer, Q 2 . Typically this parametrization is constrained to be consistent with experimental data for the neutron charge radius. However, we find that the Galster form does not have sufficient freedom to accommodate reasonable values of the radius without constraining or compromising the fit. In addition, the G E n data are now at sufficient precision to motivate a two-parameter fit (or three parameters if we include thermal neutron data). Here we present a modified form of a two-dipole parametrization that allows this freedom and fits both G E n (including recent data at both low and high four-momentum transfer) and the charge radius well with simple, well-defined parameters. Analysis reveals that the Galster form is essentially a two-parameter approximation to the two-dipole form but becomes degenerate if we try to extend it naturally to three parameters.

Scaling high-order harmonic generation from laser-solid interactions to ultrahigh intensity.

Science.gov (United States)

Dollar, F; Cummings, P; Chvykov, V; Willingale, L; Vargas, M; Yanovsky, V; Zulick, C; Maksimchuk, A; Thomas, A G R; Krushelnick, K

2013-04-26

Coherent x-ray beams with a subfemtosecond (scale length, which can strongly influence the harmonic generation mechanism. It is shown that for intensities in excess of 10(21)  W cm(-2) an optimum density ramp scale length exists that balances an increase in efficiency with a growth of parametric plasma wave instabilities. We show that for these higher intensities the optimal scale length is c/ω0, for which a variety of HOHG properties are optimized, including total conversion efficiency, HOHG divergence, and their power law scaling. Particle-in-cell simulations show striking evidence of the HOHG loss mechanism through parametric instabilities and relativistic self-phase modulation, which affect the produced spectra and conversion efficiency.

Dissecting the intensely star-forming clumps in a z ~ 2 Einstein Ring

Science.gov (United States)

Rujopakarn, Wiphu

2013-10-01

Clumps of star formation spreading widely in galactic disks are common features of star-forming galaxies at 1 test cases to study the mechanism that drives intense star formation at z ~ 2. We propose WFC3 near-IR imaging and spatially-resolved spectroscopy of a gravitationally lensed, kinematically ordered, vigorously star-forming galaxy at z = 1.885 with physical resolutions up to 40 pc. This galaxy contains two luminous clumps that are forming stars at the rates of 100 solar mass/yr/clump. Spatially-resolved map of star formation from HST provides the most critical missing piece to interpret our existing observations of this galaxy in far-IR, CO emission lines, and radio continuum. We will probe the frontier research areas in z ~ 2 star formation, particularly the spatially-resolved star formation laws and dynamics of cold and ionized gases, which have never been probed at this spatial resolution. Our proposed observations will provide a benchmark against which to interpret the structures of vigorous star-forming clumps in general. This object can therefore have a unique impact on our understanding of the star-forming modes that dominate at z ~ 2.

Engineering-Scale Demonstration of DuraLith and Ceramicrete Waste Forms

Energy Technology Data Exchange (ETDEWEB)

Josephson, Gary B.; Westsik, Joseph H.; Pires, Richard P.; Bickford, Jody; Foote, Martin W.

2011-09-23

To support the selection of a waste form for the liquid secondary wastes from the Hanford Waste Immobilization and Treatment Plant, Washington River Protection Solutions (WRPS) has initiated secondary waste form testing on four candidate waste forms. Two of the candidate waste forms have not been developed to scale as the more mature waste forms. This work describes engineering-scale demonstrations conducted on Ceramicrete and DuraLith candidate waste forms. Both candidate waste forms were successfully demonstrated at an engineering scale. A preliminary conceptual design could be prepared for full-scale production of the candidate waste forms. However, both waste forms are still too immature to support a detailed design. Formulations for each candidate waste form need to be developed so that the material has a longer working time after mixing the liquid and solid constituents together. Formulations optimized based on previous lab studies did not have sufficient working time to support large-scale testing. The engineering-scale testing was successfully completed using modified formulations. Further lab development and parametric studies are needed to optimize formulations with adequate working time and assess the effects of changes in raw materials and process parameters on the final product performance. Studies on effects of mixing intensity on the initial set time of the waste forms are also needed.

Developing a Parametric Urban Design Tool

DEFF Research Database (Denmark)

Steinø, Nicolai; Obeling, Esben

2014-01-01

Parametric urban design is a potentially powerful tool for collaborative urban design processes. Rather than making one- off designs which need to be redesigned from the ground up in case of changes, parametric design tools make it possible keep the design open while at the same time allowing...... for a level of detailing which is high enough to facilitate an understan- ding of the generic qualities of proposed designs. Starting from a brief overview of parametric design, this paper presents initial findings from the development of a parametric urban design tool with regard to developing a structural...... logic which is flexible and expandable. It then moves on to outline and discuss further development work. Finally, it offers a brief reflection on the potentials and shortcomings of the software – CityEngine – which is used for developing the parametric urban design tool....

Forms and genesis of species abundance distributions

Directory of Open Access Journals (Sweden)

Evans O. Ochiaga

2015-12-01

Full Text Available Species abundance distribution (SAD is one of the most important metrics in community ecology. SAD curves take a hollow or hyperbolic shape in a histogram plot with many rare species and only a few common species. In general, the shape of SAD is largely log-normally distributed, although the mechanism behind this particular SAD shape still remains elusive. Here, we aim to review four major parametric forms of SAD and three contending mechanisms that could potentially explain this highly skewed form of SAD. The parametric forms reviewed here include log series, negative binomial, lognormal and geometric distributions. The mechanisms reviewed here include the maximum entropy theory of ecology, neutral theory and the theory of proportionate effect.

Comparative parametric numerical simulations of materials used as liners in the explosively formed projectiles (EFPs)

International Nuclear Information System (INIS)

Hussain, G.; Sanaullah, K.

2009-01-01

A conventional shaped charge comprises a conical metal liner projecting a hyper velocity jet of metal that is able to penetrate to great depths into steel armour. However, misalignment problems exist in tandem with jet break up and spewing particles that greatly diminish its penetration power. An EFP, on the other hand, has a liner in the shape of a geometrical recess. The force of the blast molds the liner into a number of configurations, depending on the geometry and the explosive detonation characteristics. This paper presents comparative parametric numerical simulations of materials used as liners in the explosively formed projectiles EFPs. Numerical simulations are carried out using AUTODYN 2D hydrocode to study effects of liner's materials on the shape, velocity, traveled distance, time, pressure, internal energy, temperature, yield stress, divergence or stability, density, compression, and length to diameter (L/D) ratio of EFPs. These parameters are estimated at the instants of maximum as well as at stable velocities. The parametric study reveals that aluminum has maximum velocity in shortest time among the liner materials. From this reason, it was concluded effective standoff was greater for aluminum than more denser metals. Maximum velocity and traveled distance of Tantalum EFP is found to be minimum which may be due to low thermal softening exponent and larger hardening exponent. The simulated yield stress and pressure developed in the Fe EFP reaches at maximum. The L/D ratio for Copper is found to be maximum which supports maximum penetration. From the stability point of view, 1006 MS is found to be the most reliable liner material due to minimum divergence. Generally all liner materials have similar effects of all parameters like pressure, internal energy, temperature, yield stress, divergence or stability, density, compression at the instants of maximum as well as at stable velocities except L/D ratio of EFPs. At the instant of maximum velocity, L

Suppression of Growth by Multiplicative White Noise in a Parametric Resonant System

Science.gov (United States)

Ishihara, Masamichi

2015-02-01

The growth of the amplitude in a Mathieu-like equation with multiplicative white noise is studied. To obtain an approximate analytical expression for the exponent at the extremum on parametric resonance regions, a time-interval width is introduced. To determine the exponents numerically, the stochastic differential equations are solved by a symplectic numerical method. The Mathieu-like equation contains a parameter α determined by the intensity of noise and the strength of the coupling between the variable and noise; without loss of generality, only non-negative α can be considered. The exponent is shown to decrease with α, reach a minimum and increase after that. The minimum exponent is obtained analytically and numerically. As a function of α, the minimum at α≠0, occurs on the parametric resonance regions of α=0. This minimum indicates suppression of growth by multiplicative white noise.

Ionospheric modification and parametric instabilities

International Nuclear Information System (INIS)

Fejer, J.A.

1979-01-01

Thresholds and linear growth rates for stimulated Brillouin and Raman scattering and for the parametric decay instability are derived by using arguments of energy transfer. For this purpose an expression for the ponderomotive force is derived. Conditions under which the partial pressure force due to differential dissipation exceeds the ponderomotive force are also discussed. Stimulated Brillouin and Raman scattering are weakly excited by existing incoherent backscatter radars. The parametric decay instability is strongly excited in ionospheric heating experiments. Saturation theories of the parametric decay instability are therefore described. After a brief discussion of the purely growing instability the effect of using several pumps is discussed as well as the effects of inhomogenicity. Turning to detailed theories of ionospheric heating, artificial spread F is discussed in terms of a purely growing instability where the nonlinearity is due to dissipation. Field-aligned short-scale striations are explained in terms of dissipation of the parametrically excited Langmuir waves (plasma oscillations): they might be further amplified by an explosive instability (except the magnetic equator). Broadband absorption is probably responsible for the 'overshoot' effect: the initially observed level of parametrically excited Langmuir waves is much higher than the steady state level

Detection of Parametric Roll on Ships

DEFF Research Database (Denmark)

Galeazzi, Roberto; Blanke, Mogens; Poulsen, Niels Kjølstad

2012-01-01

phenomenon could make the navigator change ship’s speed and heading, and these remedial actions could make the vessel escape the bifurcation. This chapter proposes non-parametric methods to detect the onset of parametric roll resonance. Theoretical conditions for parametric resonance are re...... on experimental data from towing tank tests and data from a container ship passing an Atlantic storm....

Stochastic stability of mechanical systems under renewal jump process parametric excitation

DEFF Research Database (Denmark)

Iwankiewicz, R.; Nielsen, Søren R.K.; Larsen, Jesper Winther

2005-01-01

A dynamic system under parametric excitation in the form of a non-Erlang renewal jump process is considered. The excitation is a random train of nonoverlapping rectangular pulses with equal, deterministic heights. The time intervals between two consecutive jumps up (or down), are the sum of two...

Hyperbolic and semi-parametric models in finance

Science.gov (United States)

Bingham, N. H.; Kiesel, Rüdiger

2001-02-01

The benchmark Black-Scholes-Merton model of mathematical finance is parametric, based on the normal/Gaussian distribution. Its principal parametric competitor, the hyperbolic model of Barndorff-Nielsen, Eberlein and others, is briefly discussed. Our main theme is the use of semi-parametric models, incorporating the mean vector and covariance matrix as in the Markowitz approach, plus a non-parametric part, a scalar function incorporating features such as tail-decay. Implementation is also briefly discussed.

CONSTRUCTION THE BRIDGE PIER AS PARAMETRIC OBJECT USING AUTODESK REVIT

Directory of Open Access Journals (Sweden)

K. I. Hladka

2017-08-01

Full Text Available Purpose. The work is aimed to solve the following tasks: 1 to investigate the possibilities of Autodesk Revit to create parametric objects; 2 to create an information model of the bridge pier with the possibility of changing the model size without changing geometry of the object; 3 to trace the complexity and feasibility of using parametric models when designing the elements of bridges. Methodology. The studies were carried out using spatial modeling in the Autodesk Revit system. The ratio of the parameters of the object was set, the relationship between individual geometric elements was determined and the changes that were made to the model with the change of the specified parameters were checked. Findings. Support model of two types has been created: for railway bridges and for road bridges. Both types of models change the dimensions and the number of constituent elements in accordance with the entered parameters. The performed work confirms the possibility of creating information parametric models of complex form and the expediency of using them in the design of bridges and not only. Originality. Creation of information models is a modern and relevant topic. But both in the literature and in Internet resources, parametrization is considered on the example of simple objects. The model proposed in the article consists of several dependent geometric bodies; therefore, it opens the topic of objects parameterization more fully and in detail, in comparison with the existing sources. As for the creation of parametric models of the bridge elements - such information is not found in the literature, that is, it is proposed for the first time. Practical value. Parametrization of spatial models allows significantly to accelerate and simplify the process of designing any objects due to the use of typical parametric models in many projects. Especially it concerns the design of bridges, since the standard elements for them, such as support or span are not

Efficient primary and parametric resonance excitation of bistable resonators

KAUST Repository

Ramini, Abdallah

2016-09-12

We experimentally demonstrate an efficient approach to excite primary and parametric (up to the 4th) resonance of Microelectromechanical system MEMS arch resonators with large vibrational amplitudes. A single crystal silicon in-plane arch microbeam is fabricated such that it can be excited axially from one of its ends by a parallel-plate electrode. Its micro/nano scale vibrations are transduced using a high speed camera. Through the parallel-plate electrode, a time varying electrostatic force is applied, which is converted into a time varying axial force that modulates dynamically the stiffness of the arch resonator. Due to the initial curvature of the structure, not only parametric excitation is induced, but also primary resonance. Experimental investigation is conducted comparing the response of the arch near primary resonance using the axial excitation to that of a classical parallel-plate actuation where the arch itself forms an electrode. The results show that the axial excitation can be more efficient and requires less power for primary resonance excitation. Moreover, unlike the classical method where the structure is vulnerable to the dynamic pull-in instability, the axial excitation technique can provide large amplitude motion while protecting the structure from pull-in. In addition to primary resonance, parametrical resonances are demonstrated at twice, one-half, and two-thirds the primary resonance frequency. The ability to actuate primary and/or parametric resonances can serve various applications, such as for resonator based logic and memory devices. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

Asymptotic inference for jump diffusions with state-dependent intensity

NARCIS (Netherlands)

Becheri, Gaia; Drost, Feico; Werker, Bas

2016-01-01

We establish the local asymptotic normality property for a class of ergodic parametric jump-diffusion processes with state-dependent intensity and known volatility function sampled at high frequency. We prove that the inference problem about the drift and jump parameters is adaptive with respect to

Parametric nanomechanical amplification at very high frequency.

Science.gov (United States)

Karabalin, R B; Feng, X L; Roukes, M L

2009-09-01

Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modulates longitudinal stress in doubly clamped beam NEMS resonators. Parametric pumping and signal amplification are demonstrated for VHF resonators up to approximately 130 MHz and provide useful enhancement of both resonance signal amplitude and quality factor. We find that Joule heating and reduced thermal conductance in these nanostructures ultimately impose an upper limit to device performance. We develop a theoretical model to account for both the parametric response and nonequilibrium thermal transport in these composite nanostructures. The results closely conform to our experimental observations, elucidate the frequency and threshold-voltage scaling in parametric VHF NEMS resonators and sensors, and establish the ultimate sensitivity limits of this approach.

Parametric and non-parametric approach for sensory RATA (Rate-All-That-Apply) method of ledre profile attributes

Science.gov (United States)

Hastuti, S.; Harijono; Murtini, E. S.; Fibrianto, K.

2018-03-01

This current study is aimed to investigate the use of parametric and non-parametric approach for sensory RATA (Rate-All-That-Apply) method. Ledre as Bojonegoro unique local food product was used as point of interest, in which 319 panelists were involved in the study. The result showed that ledre is characterized as easy-crushed texture, sticky in mouth, stingy sensation and easy to swallow. It has also strong banana flavour with brown in colour. Compared to eggroll and semprong, ledre has more variances in terms of taste as well the roll length. As RATA questionnaire is designed to collect categorical data, non-parametric approach is the common statistical procedure. However, similar results were also obtained as parametric approach, regardless the fact of non-normal distributed data. Thus, it suggests that parametric approach can be applicable for consumer study with large number of respondents, even though it may not satisfy the assumption of ANOVA (Analysis of Variances).

Experimental Sentinel-2 LAI estimation using parametric, non-parametric and physical retrieval methods - A comparison

NARCIS (Netherlands)

Verrelst, Jochem; Rivera, Juan Pablo; Veroustraete, Frank; Muñoz-Marí, Jordi; Clevers, J.G.P.W.; Camps-Valls, Gustau; Moreno, José

2015-01-01

Given the forthcoming availability of Sentinel-2 (S2) images, this paper provides a systematic comparison of retrieval accuracy and processing speed of a multitude of parametric, non-parametric and physically-based retrieval methods using simulated S2 data. An experimental field dataset (SPARC),

Forest - added Turbulence: A parametric study on Turbulence intensity in and around forests

International Nuclear Information System (INIS)

Pedersen, Henrik Sundgaard; Langreder, Wiebke

2007-01-01

The scope of the investigation is to take on-site measured wind data from a number of sites inside and close to forests. From the collected on-site data the ambient turbulence intensity is calculated and analysed depending on the distance to the forest and height above the forest. From this forest turbulence intensity database it is possible to get an overview of the general behaviour of the turbulence above and down stream from the forest. The database currently consists of 65 measurements points from around the globe, and it will be continually updated as relevant sites are made available. Using the database a number of questions can be answered. How does the ambient turbulence intensity decay with height? What does the turbulence profile look like according to wind speed? Is it the general situation that high wind speeds are creating movement in the canopy tops, resulting in higher turbulence? How does the ambient turbulence intensity decay at different height as a function of distance to the forest? From the forest turbulence database it can be seen that in general, the majority of the turbulence intensity created by the forest is visible within a radius of 5 times the forest height in vertical and 500 meters downstream from the forest edge in horizontal direction. Outside these boundaries the ambient turbulence intensity is rapidly approaching normal values

Unified triminimal parametrizations of quark and lepton mixing matrices

International Nuclear Information System (INIS)

He Xiaogang; Li Shiwen; Ma Boqiang

2009-01-01

We present a detailed study on triminimal parametrizations of quark and lepton mixing matrices with different basis matrices. We start with a general discussion on the triminimal expansion of the mixing matrix and on possible unified quark and lepton parametrization using quark-lepton complementarity. We then consider several interesting basis matrices and compare the triminimal parametrizations with the Wolfenstein-like parametrizations. The usual Wolfenstein parametrization for quark mixing is a triminimal expansion around the unit matrix as the basis. The corresponding quark-lepton complementarity lepton mixing matrix is a triminimal expansion around the bimaximal basis. Current neutrino oscillation data show that the lepton mixing matrix is very well represented by the tribimaximal mixing. It is natural to take it as an expanding basis. The corresponding zeroth order basis for quark mixing in this case makes the triminimal expansion converge much faster than the usual Wolfenstein parametrization. The triminimal expansion based on tribimaximal mixing can be converted to the Wolfenstein-like parametrizations discussed in the literature. We thus have a unified description between different kinds of parametrizations for quark and lepton sectors: the standard parametrizations, the Wolfenstein-like parametrizations, and the triminimal parametrizations.

A New and General Formulation of the Parametric HFGMC Micromechanical Method for Three-Dimensional Multi-Phase Composites

Science.gov (United States)

Haj-Ali, Rami; Aboudi, Jacob

2012-01-01

The recent two-dimensional (2-D) parametric formulation of the high fidelity generalized method of cells (HFGMC) reported by the authors is generalized for the micromechanical analysis of three-dimensional (3-D) multiphase composites with periodic microstructure. Arbitrary hexahedral subcell geometry is developed to discretize a triply periodic repeating unit-cell (RUC). Linear parametric-geometric mapping is employed to transform the arbitrary hexahedral subcell shapes from the physical space to an auxiliary orthogonal shape, where a complete quadratic displacement expansion is performed. Previously in the 2-D case, additional three equations are needed in the form of average moments of equilibrium as a result of the inclusion of the bilinear terms. However, the present 3-D parametric HFGMC formulation eliminates the need for such additional equations. This is achieved by expressing the coefficients of the full quadratic polynomial expansion of the subcell in terms of the side or face average-displacement vectors. The 2-D parametric and orthogonal HFGMC are special cases of the present 3-D formulation. The continuity of displacements and tractions, as well as the equilibrium equations, are imposed in the average (integral) sense as in the original HFGMC formulation. Each of the six sides (faces) of a subcell has an independent average displacement micro-variable vector which forms an energy-conjugate pair with the transformed average-traction vector. This allows generating symmetric stiffness matrices along with internal resisting vectors for the subcells which enhances the computational efficiency. The established new parametric 3-D HFGMC equations are formulated and solution implementations are addressed. Several applications for triply periodic 3-D composites are presented to demonstrate the general capability and varsity of the present parametric HFGMC method for refined micromechanical analysis by generating the spatial distributions of local stress fields

Pump-to-Signal Intensity Modulation Transfer in Saturated- Gain Fiber Optical Parametric Amplifiers

DEFF Research Database (Denmark)

Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Rottwitt, Karsten

2011-01-01

The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime....

PARAMETRIC INSURANCE COVER FOR NATURAL CATASTROPHE RISKS

Directory of Open Access Journals (Sweden)

Serghei Margulescu

2013-11-01

Full Text Available With economic losses of over USD 370 bn caused by 325 catastrophic events, 2011 ranks as the worst ever year in terms of costs to society due to natural catastrophes and man-made disasters. Inthe same time, 2011 is the second most expensive year in the history for the insurance industry, with insured losses from catastrophic events amounting to USD 116 bn. Both the high level of damages and insured losses, as well as the unprecedented gap between the two values, made insurers and reinsurers worldwide to understand that some risks had so far been underestimated and they have to be better integrated in the catastrophes modelling.On the other hand, governments have to protect themselves against the financial impact of natural catastrophes and new forms of cooperation between the public and private sectors can help countries finance disaster risks. Viewed in a country’s wider risk management context, the purchase of parametric insurance cover, which transfers natural catastrophe risk to the private sector using an index- based trigger, is a necessary shift towards a pre-emptive risk management strategy. This kind of approach can be pursued by central governments or at the level of provincial or municipal governments, and a number of case studies included in the publication “Closing the financial gap” by Swiss Re (2011 illustrates how new forms of parametric insurance can help countries finance disaster risks.

Impact of temporal, spatial and cascaded effects on the pulse formation in ultra-broadband parametric amplifiers.

Science.gov (United States)

Lang, T; Harth, A; Matyschok, J; Binhammer, T; Schultze, M; Morgner, U

2013-01-14

A 2 + 1 dimensional nonlinear pulse propagation model is presented, illustrating the weighting of different effects for the parametric amplification of ultra-broadband spectra in different regimes of energy scaling. Typical features in the distribution of intensity and phase of state-of-the-art OPA-systems can be understood by cascaded spatial and temporal effects.

Explicit/multi-parametric model predictive control (MPC) of linear discrete-time systems by dynamic and multi-parametric programming

KAUST Repository

Kouramas, K.I.

2011-08-01

This work presents a new algorithm for solving the explicit/multi- parametric model predictive control (or mp-MPC) problem for linear, time-invariant discrete-time systems, based on dynamic programming and multi-parametric programming techniques. The algorithm features two key steps: (i) a dynamic programming step, in which the mp-MPC problem is decomposed into a set of smaller subproblems in which only the current control, state variables, and constraints are considered, and (ii) a multi-parametric programming step, in which each subproblem is solved as a convex multi-parametric programming problem, to derive the control variables as an explicit function of the states. The key feature of the proposed method is that it overcomes potential limitations of previous methods for solving multi-parametric programming problems with dynamic programming, such as the need for global optimization for each subproblem of the dynamic programming step. © 2011 Elsevier Ltd. All rights reserved.

A reduced-form intensity-based model under fuzzy environments

Science.gov (United States)

Wu, Liang; Zhuang, Yaming

2015-05-01

The external shocks and internal contagion are the important sources of default events. However, the external shocks and internal contagion effect on the company is not observed, we cannot get the accurate size of the shocks. The information of investors relative to the default process exhibits a certain fuzziness. Therefore, using randomness and fuzziness to study such problems as derivative pricing or default probability has practical needs. But the idea of fuzzifying credit risk models is little exploited, especially in a reduced-form model. This paper proposes a new default intensity model with fuzziness and presents a fuzzy default probability and default loss rate, and puts them into default debt and credit derivative pricing. Finally, the simulation analysis verifies the rationality of the model. Using fuzzy numbers and random analysis one can consider more uncertain sources in the default process of default and investors' subjective judgment on the financial markets in a variety of fuzzy reliability so as to broaden the scope of possible credit spreads.

Hamiltonian description of the parametrized scalar field in bounded spatial regions

International Nuclear Information System (INIS)

Barbero G, J Fernando; Margalef-Bentabol, Juan; Villaseñor, Eduardo J S

2016-01-01

We study the Hamiltonian formulation for a parametrized scalar field in a regular bounded spatial region subject to Dirichlet, Neumann and Robin boundary conditions. We generalize the work carried out by a number of authors on parametrized field systems to the interesting case where spatial boundaries are present. The configuration space of our models contains both smooth scalar fields defined on the spatial manifold and spacelike embeddings from the spatial manifold to a target spacetime endowed with a fixed Lorentzian background metric. We pay particular attention to the geometry of the infinite dimensional manifold of embeddings and the description of the relevant geometric objects: the symplectic form on the primary constraint submanifold and the Hamiltonian vector fields defined on it. (paper)

Parametric representation of centrifugal pump homologous curves

International Nuclear Information System (INIS)

Veloso, Marcelo A.; Mattos, Joao R.L. de

2015-01-01

Essential for any mathematical model designed to simulate flow transient events caused by pump operations is the pump performance data. The performance of a centrifugal pump is characterized by four basic quantities: the rotational speed, the volumetric flow rate, the dynamic head, and the hydraulic torque. The curves showing the relationships between these four variables are called the pump characteristic curves. The characteristic curves are empirically developed by the pump manufacturer and uniquely describe head and torque as functions of volumetric flow rate and rotation speed. Because of comprising a large amount of points, this configuration is not suitable for computational purposes. However, it can be converted to a simpler form by the development of the homologous curves, in which dynamic head and hydraulic torque ratios are expressed as functions of volumetric flow and rotation speed ratios. The numerical use of the complete set of homologous curves requires specification of sixteen partial curves, being eight for the dynamic head and eight for the hydraulic torque. As a consequence, the handling of homologous curves is still somewhat complicated. In solving flow transient problems that require the pump characteristic data for all the operation zones, the parametric form appears as the simplest way to deal with the homologous curves. In this approach, the complete characteristics of a pump can be described by only two closed curves, one for the dynamic head and other for the hydraulic torque, both in function of a single angular coordinate defined adequately in terms of the quotient between volumetric flow ratio and rotation speed ratio. The usefulness and advantages of this alternative method are demonstrated through a practical example in which the homologous curves for a pump of the type used in the main coolant loops of a pressurized water reactor (PWR) are transformed to the parametric form. (author)

Effects of free-stream turbulence intensity on transition in a laminar separation bubble formed over an airfoil

Science.gov (United States)

Istvan, Mark S.; Yarusevych, Serhiy

2018-03-01

The laminar-to-turbulent transition process in a laminar separation bubble formed over a NACA 0018 airfoil is investigated experimentally. All experiments are performed for an angle of attack of 4°, chord Reynolds numbers of 80,000 and 125,000, and free-stream turbulence intensities between 0.06 and 1.99%. The results show that increasing the level of free-stream turbulence intensity leads to a decrease in separation bubble length, attributed to a downstream shift in mean separation and an upstream shift in mean reattachment, the later ascribed to an upstream shift in mean transition. Maximum spatial amplification rates of disturbances in the separated shear layer decrease with increasing free-stream turbulence intensity, implying that the larger initial amplitudes of disturbances are solely responsible for the upstream shift in mean transition and as a result mean reattachment. At the baseline level of turbulence intensity, coherent structures forming in the aft portion of the bubble are characterized by strong spanwise coherence at formation, and undergo spanwise deformations leading to localized breakup in the vicinity of mean reattachment. As the level of free-stream turbulence intensity is increased, the spanwise coherence of the shear layer rollers is reduced, and spanwise undulations in the vortex filaments start to take place at the mean location of roll-up. At the highest level of turbulence intensity investigated, streamwise streaks originating in the boundary layer upstream of the separation bubble are observed within the bubble. These streaks signify an onset of bypass transition upstream of the separation bubble, which gives rise to a highly three-dimensional shear layer roll-up. A quantitative analysis of the associated changes in salient characteristics of the coherent structures is presented, connecting the effect of elevated free-stream turbulence intensity on the time-averaged and dynamic characteristics of the separation bubble.

Theoretical and algorithmic advances in multi-parametric programming and control

KAUST Repository

Pistikopoulos, Efstratios N.; Dominguez, Luis; Panos, Christos; Kouramas, Konstantinos; Chinchuluun, Altannar

2012-01-01

This paper presents an overview of recent theoretical and algorithmic advances, and applications in the areas of multi-parametric programming and explicit/multi-parametric model predictive control (mp-MPC). In multi-parametric programming, advances include areas such as nonlinear multi-parametric programming (mp-NLP), bi-level programming, dynamic programming and global optimization for multi-parametric mixed-integer linear programming problems (mp-MILPs). In multi-parametric/explicit MPC (mp-MPC), advances include areas such as robust multi-parametric control, multi-parametric nonlinear MPC (mp-NMPC) and model reduction in mp-MPC. A comprehensive framework for multi-parametric programming and control is also presented. Recent applications include a hydrogen storage device, a fuel cell power generation system, an unmanned autonomous vehicle (UAV) and a hybrid pressure swing adsorption (PSA) system. © 2012 Springer-Verlag.

Theoretical and algorithmic advances in multi-parametric programming and control

KAUST Repository

Pistikopoulos, Efstratios N.

2012-04-21

This paper presents an overview of recent theoretical and algorithmic advances, and applications in the areas of multi-parametric programming and explicit/multi-parametric model predictive control (mp-MPC). In multi-parametric programming, advances include areas such as nonlinear multi-parametric programming (mp-NLP), bi-level programming, dynamic programming and global optimization for multi-parametric mixed-integer linear programming problems (mp-MILPs). In multi-parametric/explicit MPC (mp-MPC), advances include areas such as robust multi-parametric control, multi-parametric nonlinear MPC (mp-NMPC) and model reduction in mp-MPC. A comprehensive framework for multi-parametric programming and control is also presented. Recent applications include a hydrogen storage device, a fuel cell power generation system, an unmanned autonomous vehicle (UAV) and a hybrid pressure swing adsorption (PSA) system. © 2012 Springer-Verlag.

Electroweak form factors of the Skyrmion

International Nuclear Information System (INIS)

Braaten, E.; Sze-Man Tse; Willcox, C.

1986-01-01

The electroweak form factors of baryons are studied in the semiclassical approximation to the Skyrme model. General expressions for the form factors are given for arbitrary choices of the Skyrme-model Lagrangian. They are applied to the original two-parameter Skyrme model to compute the electric, magnetic, and axial-vector form factors of the nucleon and the electromagnetic nucleon-Δ transition form factors. The dependence of the form factors on the momentum transfer is compared with phenomenological dipole parametrizations

PARAMETRIC DRAWINGS VS. AUTOLISP

OpenAIRE

PRUNĂ Liviu; SLONOVSCHI Andrei

2015-01-01

In this paper the authors make a critical analysis of the advantages offered by the parametric drawing use by comparison with the AutoLISP computer programs used when it comes about the parametric design. Studying and analysing these two work models the authors have got to some ideas and conclusions which should be considered in the moment in that someone must to decide if it is the case to elaborate a software, using the AutoLISP language, or to establish the base rules that must be followed...

Parametric Bayesian Estimation of Differential Entropy and Relative Entropy

Directory of Open Access Journals (Sweden)

Maya Gupta

2010-04-01

Full Text Available Given iid samples drawn from a distribution with known parametric form, we propose the minimization of expected Bregman divergence to form Bayesian estimates of differential entropy and relative entropy, and derive such estimators for the uniform, Gaussian, Wishart, and inverse Wishart distributions. Additionally, formulas are given for a log gamma Bregman divergence and the differential entropy and relative entropy for the Wishart and inverse Wishart. The results, as always with Bayesian estimates, depend on the accuracy of the prior parameters, but example simulations show that the performance can be substantially improved compared to maximum likelihood or state-of-the-art nonparametric estimators.

Estimating technical efficiency in the hospital sector with panel data: a comparison of parametric and non-parametric techniques.

Science.gov (United States)

Siciliani, Luigi

2006-01-01

Policy makers are increasingly interested in developing performance indicators that measure hospital efficiency. These indicators may give the purchasers of health services an additional regulatory tool to contain health expenditure. Using panel data, this study compares different parametric (econometric) and non-parametric (linear programming) techniques for the measurement of a hospital's technical efficiency. This comparison was made using a sample of 17 Italian hospitals in the years 1996-9. Highest correlations are found in the efficiency scores between the non-parametric data envelopment analysis under the constant returns to scale assumption (DEA-CRS) and several parametric models. Correlation reduces markedly when using more flexible non-parametric specifications such as data envelopment analysis under the variable returns to scale assumption (DEA-VRS) and the free disposal hull (FDH) model. Correlation also generally reduces when moving from one output to two-output specifications. This analysis suggests that there is scope for developing performance indicators at hospital level using panel data, but it is important that extensive sensitivity analysis is carried out if purchasers wish to make use of these indicators in practice.

Connections between classical and parametric network entropies.

Directory of Open Access Journals (Sweden)

Matthias Dehmer

Full Text Available This paper explores relationships between classical and parametric measures of graph (or network complexity. Classical measures are based on vertex decompositions induced by equivalence relations. Parametric measures, on the other hand, are constructed by using information functions to assign probabilities to the vertices. The inequalities established in this paper relating classical and parametric measures lay a foundation for systematic classification of entropy-based measures of graph complexity.

Dual parametrization of generalized parton distributions in two equivalent representations

International Nuclear Information System (INIS)

Müller, D.; Polyakov, M.V.; Semenov-Tian-Shansky, K.M.

2015-01-01

The dual parametrization and the Mellin-Barnes integral approach represent two frameworks for handling the double partial wave expansion of generalized parton distributions (GPDs) in the conformal partial waves and in the t-channel SO(3) partial waves. Within the dual parametrization framework, GPDs are represented as integral convolutions of forward-like functions whose Mellin moments generate the conformal moments of GPDs. The Mellin-Barnes integral approach is based on the analytic continuation of the GPD conformal moments to the complex values of the conformal spin. GPDs are then represented as the Mellin-Barnes-type integrals in the complex conformal spin plane. In this paper we explicitly show the equivalence of these two independently developed GPD representations. Furthermore, we clarify the notions of the J=0 fixed pole and the D-form factor. We also provide some insight into GPD modeling and map the phenomenologically successful Kumerički-Müller GPD model to the dual parametrization framework by presenting the set of the corresponding forward-like functions. We also build up the reparametrization procedure allowing to recast the double distribution representation of GPDs in the Mellin-Barnes integral framework and present the explicit formula for mapping double distributions into the space of double partial wave amplitudes with complex conformal spin.

Stress-intensity factor equations for cracks in three-dimensional finite bodies

Science.gov (United States)

Newman, J. C., Jr.; Raju, I. S.

1981-01-01

Empirical stress intensity factor equations are presented for embedded elliptical cracks, semi-elliptical surface cracks, quarter-elliptical corner cracks, semi-elliptical surface cracks at a hole, and quarter-elliptical corner cracks at a hole in finite plates. The plates were subjected to remote tensile loading. Equations give stress intensity factors as a function of parametric angle, crack depth, crack length, plate thickness, and where applicable, hole radius. The stress intensity factors used to develop the equations were obtained from three dimensional finite element analyses of these crack configurations.

Absolute decay parametric instability of high-temperature plasma

International Nuclear Information System (INIS)

Zozulya, A.A.; Silin, V.P.; Tikhonchuk, V.T.

1986-01-01

A new absolute decay parametric instability having wide spatial localization region is shown to be possible near critical plasma density. Its excitation is conditioned by distributed feedback of counter-running Langmuir waves occurring during parametric decay of incident and reflected pumping wave components. In a hot plasma with the temperature of the order of kiloelectronvolt its threshold is lower than that of a known convective decay parametric instability. Minimum absolute instability threshold is shown to be realized under conditions of spatial parametric resonance of higher orders

Nonscaling parametrization of hadronic spectra and dual parton model

International Nuclear Information System (INIS)

Gaponenko, O.N.

2001-01-01

Using the popular Wdowczyk-Wolfendale parametrization (WW-parametrization) as an example one studies restrictions imposed by a dual parton model for different nonscaling parametrizations of the pulsed hadron spectra in soft hadron-hadron and hadron-nuclear interactions. One derived a new parametrization free from basic drawback of the WW-formulae. In the central range the determined parametrization show agreement with the Wdowczyk-Wolfendale formula, but in contrast to the last-named one it does not result in contradiction with the experiment due to fast reduction of inelastic factor reduction with energy increase [ru

Parametric Methods for Order Tracking Analysis

DEFF Research Database (Denmark)

Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm

2017-01-01

Order tracking analysis is often used to find the critical speeds at which structural resonances are excited by a rotating machine. Typically, order tracking analysis is performed via non-parametric methods. In this report, however, we demonstrate some of the advantages of using a parametric method...

Three-dimensional parametrization of photon-initiated high energy showers

International Nuclear Information System (INIS)

De Angelis, A.

1988-01-01

A three-dimensional parametrization of photon-initiated showers in a homogeneous absorber is presented. The form, suggested by a model assimilating the transverse shower development to a random walk process, displays a simple scaling with the primary energy, and is very suitable for numerical integration. The parameters are explicitly calculated for the case of showers in SF5 lead glass, and the results are compared with the explicit simulation by GEANT3.11. Fields of application are investigated. (orig.)

Explicit/multi-parametric model predictive control (MPC) of linear discrete-time systems by dynamic and multi-parametric programming

KAUST Repository

Kouramas, K.I.; Faí sca, N.P.; Panos, C.; Pistikopoulos, E.N.

2011-01-01

This work presents a new algorithm for solving the explicit/multi- parametric model predictive control (or mp-MPC) problem for linear, time-invariant discrete-time systems, based on dynamic programming and multi-parametric programming techniques

Macromechanical Parametric Amplification

DEFF Research Database (Denmark)

Neumeyer, Stefan

between the two peaks can be altered. The first experimental bistable amplified steady-state responses are also reported. The derived analytical models and experimental setups can readily be extended to investigate other factors. Some of the results are also applicable to the more general field of systems...... for energy harvesting. Using analytical, numerical, and experimental methods, the thesis focuses on superthreshold pumping (above the systems parametric instability threshold), nonlinear effects, frequency response backbones, and frequency detuning effects for parametric amplifiers. Part one of the thesis...... covers superthreshold pumping and nonlinear effects. Superthresh-old pumping produces some useful characteristics. For instance, strong superthreshold pumping yields a high gain even though nonlinear effects tend to reduce it. In addition, a narrower excitation phase range is realized for which...

Comparative Study of Parametric and Non-parametric Approaches in Fault Detection and Isolation

DEFF Research Database (Denmark)

Katebi, S.D.; Blanke, M.; Katebi, M.R.

This report describes a comparative study between two approaches to fault detection and isolation in dynamic systems. The first approach uses a parametric model of the system. The main components of such techniques are residual and signature generation for processing and analyzing. The second...... approach is non-parametric in the sense that the signature analysis is only dependent on the frequency or time domain information extracted directly from the input-output signals. Based on these approaches, two different fault monitoring schemes are developed where the feature extraction and fault decision...

Tremor Detection Using Parametric and Non-Parametric Spectral Estimation Methods: A Comparison with Clinical Assessment

Science.gov (United States)

Martinez Manzanera, Octavio; Elting, Jan Willem; van der Hoeven, Johannes H.; Maurits, Natasha M.

2016-01-01

In the clinic, tremor is diagnosed during a time-limited process in which patients are observed and the characteristics of tremor are visually assessed. For some tremor disorders, a more detailed analysis of these characteristics is needed. Accelerometry and electromyography can be used to obtain a better insight into tremor. Typically, routine clinical assessment of accelerometry and electromyography data involves visual inspection by clinicians and occasionally computational analysis to obtain objective characteristics of tremor. However, for some tremor disorders these characteristics may be different during daily activity. This variability in presentation between the clinic and daily life makes a differential diagnosis more difficult. A long-term recording of tremor by accelerometry and/or electromyography in the home environment could help to give a better insight into the tremor disorder. However, an evaluation of such recordings using routine clinical standards would take too much time. We evaluated a range of techniques that automatically detect tremor segments in accelerometer data, as accelerometer data is more easily obtained in the home environment than electromyography data. Time can be saved if clinicians only have to evaluate the tremor characteristics of segments that have been automatically detected in longer daily activity recordings. We tested four non-parametric methods and five parametric methods on clinical accelerometer data from 14 patients with different tremor disorders. The consensus between two clinicians regarding the presence or absence of tremor on 3943 segments of accelerometer data was employed as reference. The nine methods were tested against this reference to identify their optimal parameters. Non-parametric methods generally performed better than parametric methods on our dataset when optimal parameters were used. However, one parametric method, employing the high frequency content of the tremor bandwidth under consideration

Internal dynamics of intense twin beams and their coherence

Czech Academy of Sciences Publication Activity Database

Peřina Jr., J.; Haderka, Ondřej; Allevi, A.; Bondani, M.

2016-01-01

Roč. 6, Feb (2016), 1-8, č. článku 22320. ISSN 2045-2322 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : dynamics of intense * twin beams * pump-depleted parametric * down-conversion * coherence Subject RIV: BH - Optics, Masers, Lasers Impact factor: 4.259, year: 2016

Dirac delta representation by exact parametric equations.. Application to impulsive vibration systems

Science.gov (United States)

Chicurel-Uziel, Enrique

2007-08-01

A pair of closed parametric equations are proposed to represent the Heaviside unit step function. Differentiating the step equations results in two additional parametric equations, that are also hereby proposed, to represent the Dirac delta function. These equations are expressed in algebraic terms and are handled by means of elementary algebra and elementary calculus. The proposed delta representation complies exactly with the values of the definition. It complies also with the sifting property and the requisite unit area and its Laplace transform coincides with the most general form given in the tables. Furthermore, it leads to a very simple method of solution of impulsive vibrating systems either linear or belonging to a large class of nonlinear problems. Two example solutions are presented.

A general approach to optomechanical parametric instabilities

International Nuclear Information System (INIS)

Evans, M.; Barsotti, L.; Fritschel, P.

2010-01-01

We present a simple feedback description of parametric instabilities which can be applied to a variety of optical systems. Parametric instabilities are of particular interest to the field of gravitational-wave interferometry where high mechanical quality factors and a large amount of stored optical power have the potential for instability. In our use of Advanced LIGO as an example application, we find that parametric instabilities, if left unaddressed, present a potential threat to the stability of high-power operation.

Integrable multi parametric SU(N) chain

International Nuclear Information System (INIS)

Foerster, Angela; Roditi, Itzhak; Rodrigues, Ligia M.C.S.

1996-03-01

We analyse integrable models associated to a multi parametric SU(N) R-matrix. We show that the Hamiltonians describe SU(N) chains with twisted boundary conditions and that the underlying algebraic structure is the multi parametric deformation of SU(N) enlarged by the introduction of a central element. (author). 15 refs

Towards a parametrization of multiparticle hadronic reactions

International Nuclear Information System (INIS)

Giffon, M.; Hama, Y.; Predazzi, E.

1979-11-01

An explicit parametrization of high energy exclusive production cross-sections is shown to give a reasonable account of inclusive data. This is a first step towards a phenomenological parametrization of multiparticle hadronic amplitudes

Current-driven parametric resonance in magnetic multilayers

International Nuclear Information System (INIS)

Wang, C; Seinige, H; Tsoi, M

2013-01-01

Current-induced parametric excitations were observed in point-contact spin-valve nanodevices. Point contacts were used to inject high densities of direct and microwave currents into spin valves, thus producing oscillating spin-transfer and Oersted-field torques on magnetic moments. The resulting magnetodynamics were observed electrically by measuring rectified voltage signals across the contact. In addition to the spin-torque-driven ferromagnetic resonance we observe doubled-frequency signals which correspond to the parametric excitation of magnetic moments. Numerical simulations suggest that while both spin-transfer torque and ac Oersted field contribute to the parametrically excited dynamics, the ac spin torque dominates, and dc spin torque can switch it on and off. The dc bias dependence of the parametric resonance signal enabled the mapping of instability regions characterizing the nonlinearity of the oscillation. (paper)

Autonomous Supervision and Control of Parametric Roll Resonance

DEFF Research Database (Denmark)

Galeazzi, Roberto

therefore two objectives. The first is to develop methods for detection of the inception of parametric roll resonance. The second is to develop control strategies to stabilize the motion after parametric roll has started. Stabilisation of parametric roll resonance points to two possible courses of action...... strategies are then combined to stabilise parametric roll resonance within few roll cycles. Limitations on the maximum stabilisable roll angle are analysed and linked to the ii slew rate saturation and hydrodynamic stall characteristics of the fin stabilisers. The study on maximum stabilisable roll angle...... leads to the requirements for early detection. Two novel detectors are proposed, which work within a shorttime prediction horizon, and issue early warnings of parametric roll inception within few roll cycles from its onset. The main idea behind these detection schemes is that of exploiting the link...

A Review of Parametric Descriptions of Tropical Cyclone Wind-Wave Generation

Directory of Open Access Journals (Sweden)

Ian R. Young

2017-10-01

Full Text Available More than three decades of observations of tropical cyclone wind and wave fields have resulted in a detailed understanding of wave-growth dynamics, although details of the physics are still lacking. These observations are presented in a consistent manner, which provides the basis to be able to characterize the full wave spectrum in a parametric form throughout tropical cyclones. The data clearly shows that an extended fetch model can be used to represent the maximum significant wave height in such storms. The shape stabilizing influence of nonlinear interactions means that the spectral shape is remarkably similar to fetch-limited cases. As such, the tropical cyclone spectrum can also be described by using well-known parametric models. A detailed process is described to parameterize the wave spectrum at any point in a tropical cyclone.

Preliminary parametric performance assessment of potential final waste forms for alpha low-level waste at the Idaho National Engineering Laboratory. Revision 1

International Nuclear Information System (INIS)

Smith, T.H.; Sussman, M.E.; Myers, J.; Djordjevic, S.M.; DeBiase, T.A.; Goodrich, M.T.; DeWitt, D.

1995-08-01

This report presents a preliminary parametric performance assessment (PA) of potential waste disposal systems for alpha-contaminated, mixed, low-level waste (ALLW) currently stored at the Transuranic Storage Area of INEL. The ALLW, which contains from 10 to 100 nCi/g of transuranic (TRU) radionuclides, is awaiting treatment and disposal. The purpose of this study was to examine the effects of several parameters on the radiological-confinement performance of potential disposal systems for the ALLW. The principal emphasis was on the performance of final waste forms (FWFs). Three categories of FWF (cement, glass, and ceramic) were addressed by evaluating the performance of two limiting FWFs for each category. Performance at five conceptual disposal sites was evaluated to illustrate the effects of site characteristics on the performance of the total disposal system. Other parameters investigated for effects on receptor dose included inventory assumptions, TRU radionuclide concentration, FWF fracture, disposal depth, water infiltration rates, subsurface-transport modeling assumptions, receptor well location, intrusion scenario assumptions, and the absence of waste immobilization. These and other factors were varied singly and in some combinations. The results indicate that compliance of the treated and disposed ALLW with the performance objectives depends on the assumptions made, as well as on the FWF and the disposal site. Some combinations result in compliance, while others do not. The implications of these results for decision making relative to treatment and disposal of the INEL ALLW are discussed. The report compares the degree of conservatism in this preliminary parametric PA against that in four other PAs and one risk assessment. All of the assessments addressed the same disposal site, but different wastes. The report also presents a qualitative evaluation of the uncertainties in the PA and makes recommendations for further study

Bianchi surfaces: integrability in an arbitrary parametrization

International Nuclear Information System (INIS)

Nieszporski, Maciej; Sym, Antoni

2009-01-01

We discuss integrability of normal field equations of arbitrarily parametrized Bianchi surfaces. A geometric definition of the Bianchi surfaces is presented as well as the Baecklund transformation for the normal field equations in an arbitrarily chosen surface parametrization.

Parametric and Non-Parametric Vibration-Based Structural Identification Under Earthquake Excitation

Science.gov (United States)

Pentaris, Fragkiskos P.; Fouskitakis, George N.

2014-05-01

The problem of modal identification in civil structures is of crucial importance, and thus has been receiving increasing attention in recent years. Vibration-based methods are quite promising as they are capable of identifying the structure's global characteristics, they are relatively easy to implement and they tend to be time effective and less expensive than most alternatives [1]. This paper focuses on the off-line structural/modal identification of civil (concrete) structures subjected to low-level earthquake excitations, under which, they remain within their linear operating regime. Earthquakes and their details are recorded and provided by the seismological network of Crete [2], which 'monitors' the broad region of south Hellenic arc, an active seismic region which functions as a natural laboratory for earthquake engineering of this kind. A sufficient number of seismic events are analyzed in order to reveal the modal characteristics of the structures under study, that consist of the two concrete buildings of the School of Applied Sciences, Technological Education Institute of Crete, located in Chania, Crete, Hellas. Both buildings are equipped with high-sensitivity and accuracy seismographs - providing acceleration measurements - established at the basement (structure's foundation) presently considered as the ground's acceleration (excitation) and at all levels (ground floor, 1st floor, 2nd floor and terrace). Further details regarding the instrumentation setup and data acquisition may be found in [3]. The present study invokes stochastic, both non-parametric (frequency-based) and parametric methods for structural/modal identification (natural frequencies and/or damping ratios). Non-parametric methods include Welch-based spectrum and Frequency response Function (FrF) estimation, while parametric methods, include AutoRegressive (AR), AutoRegressive with eXogeneous input (ARX) and Autoregressive Moving-Average with eXogeneous input (ARMAX) models[4, 5

Tile-based rigidization surface parametric design study

Science.gov (United States)

Giner Munoz, Laura; Luntz, Jonathan; Brei, Diann; Kim, Wonhee

2018-03-01

Inflatable technologies have proven useful in consumer goods as well as in more recent applications including civil structures, aerospace, medical, and robotics. However, inflatable technologies are typically lacking in their ability to provide rigid structural support. Particle jamming improves upon this by providing structures which are normally flexible and moldable but become rigid when air is removed. Because these are based on an airtight bladder filled with loose particles, they always occupy the full volume of its rigid state, even when not rigidized. More recent developments in layer jamming have created thin, compact rigidizing surfaces replacing the loose volume of particles with thinly layered surface materials. Work in this area has been applied to several specific applications with positive results but have not generally provided the broader understanding of the rigidization performance as a function of design parameters required for directly adapting layer rigidization technology to other applications. This paper presents a parametric design study of a new layer jamming vacuum rigidization architecture: tile-based vacuum rigidization. This form of rigidization is based on layers of tiles contained within a thin vacuum bladder which can be bent, rolled, or otherwise compactly stowed, but when deployed flat, can be vacuumed and form a large, flat, rigid plate capable of supporting large forces both localized and distributed over the surface. The general architecture and operation detailing rigidization and compliance mechanisms is introduced. To quantitatively characterize the rigidization behavior, prototypes rigidization surfaces are fabricated and an experimental technique is developed based on a 3-point bending test. Performance evaluation metrics are developed to describe the stiffness, load-bearing capacity, and internal slippage of tested prototypes. A set of experimental parametric studies are performed to better understand the impact of

PARAMETRIC DRAWINGS VS. AUTOLISP

Directory of Open Access Journals (Sweden)

PRUNĂ Liviu

2015-06-01

Full Text Available In this paper the authors make a critical analysis of the advantages offered by the parametric drawing use by comparison with the AutoLISP computer programs used when it comes about the parametric design. Studying and analysing these two work models the authors have got to some ideas and conclusions which should be considered in the moment in that someone must to decide if it is the case to elaborate a software, using the AutoLISP language, or to establish the base rules that must be followed by the drawing, in the idea to construct outlines or blocks which can be used in the projection process.

Investigation of Parametric Instability of the Planetary Gear under Speed Fluctuations

Directory of Open Access Journals (Sweden)

Xinghui Qiu

2017-01-01

Full Text Available Planetary gear is widely used in engineering and usually has symmetrical structure. As the number of teeth in contact changes during rotation, the time-varying mesh stiffness parametrically excites the planetary gear and may cause severe vibrations and instabilities. Taking speed fluctuations into account, the time-varying mesh stiffness is frequency modulated, and therefore sideband instabilities may arise and original instabilities are significantly affected. Considering two different speed fluctuations, original and sideband instabilities are numerically and analytically investigated. A rotational lumped-parameter model of the planetary gear is developed, in which the time-varying mesh stiffness, input speed fluctuations, and damping are considered. Closed-form approximations of instability boundaries for primary and combination instabilities are obtained by perturbation analysis and verified by numerical analysis. The effects of speed fluctuations and damping on parametric instability are systematically examined. Because of the frequency modulation, whether a parametric instability occurs cannot be simply predicted by the planet meshing phase which is applicable to constant speed. Besides adjusting the planet meshing phase, speed fluctuation supplies a new thought to minimize certain instability by adjusting the amplitude or frequency of the speed fluctuation. Both original and sideband instabilities are shrunken by damping, and speed fluctuation further shrinks the original instability.

Fault detection and isolation in systems with parametric faults

DEFF Research Database (Denmark)

Stoustrup, Jakob; Niemann, Hans Henrik

1999-01-01

The problem of fault detection and isolation of parametric faults is considered in this paper. A fault detection problem based on parametric faults are associated with internal parameter variations in the dynamical system. A fault detection and isolation method for parametric faults is formulated...

Parametric FEM for geometric biomembranes

Science.gov (United States)

Bonito, Andrea; Nochetto, Ricardo H.; Sebastian Pauletti, M.

2010-05-01

We consider geometric biomembranes governed by an L2-gradient flow for bending energy subject to area and volume constraints (Helfrich model). We give a concise derivation of a novel vector formulation, based on shape differential calculus, and corresponding discretization via parametric FEM using quadratic isoparametric elements and a semi-implicit Euler method. We document the performance of the new parametric FEM with a number of simulations leading to dumbbell, red blood cell and toroidal equilibrium shapes while exhibiting large deformations.

Displacement of microwave squeezed states with Josephson parametric amplifiers

Energy Technology Data Exchange (ETDEWEB)

Zhong, Ling; Baust, Alexander; Xie, Edwar; Schwarz, Manuel; Gross, Rudolf [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, TU Muenchen, Garching (Germany); Nanosystems Initiative Munich (NIM), Muenchen (Germany); Fedorov, Kirill; Menzel, Edwin; Marx, Achim [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Betzenbichler, Martin; Pogorzalek, Stefan; Haeberlein, Max; Eder, Peter; Goetz, Jan; Wulschner, Karl Friedrich; Huebl, Hans; Deppe, Frank [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, TU Muenchen, Garching (Germany)

2015-07-01

Propagating quantum microwaves are promising building blocks for quantum communication. Interestingly, such itinerant quantum microwaves can be generated in the form of squeezed photon states by Josephson parametric amplifiers (JPA). We employ a specific ''dual-path'' setup for both state reconstruction and JPA characterization. Displacement operations are performed by using a directional coupler after the squeezing. We compare our results with theory predictions. In particular, we discuss our experiments in the context of remote state preparation and quantum teleportation with propagating microwaves.

Parametric analysis of ATM solar array.

Science.gov (United States)

Singh, B. K.; Adkisson, W. B.

1973-01-01

The paper discusses the methods used for the calculation of ATM solar array performance characteristics and provides the parametric analysis of solar panels used in SKYLAB. To predict the solar array performance under conditions other than test conditions, a mathematical model has been developed. Four computer programs have been used to convert the solar simulator test data to the parametric curves. The first performs module summations, the second determines average solar cell characteristics which will cause a mathematical model to generate a curve matching the test data, the third is a polynomial fit program which determines the polynomial equations for the solar cell characteristics versus temperature, and the fourth program uses the polynomial coefficients generated by the polynomial curve fit program to generate the parametric data.

Experimental implementation of a nonlinear beamsplitter based on a phase-sensitive parametric amplifier

Energy Technology Data Exchange (ETDEWEB)

Fang, Yami; Feng, Jingliang; Cao, Leiming; Wang, Yaxian; Jing, Jietai, E-mail: jtjing@phy.ecnu.edu.cn [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

2016-03-28

Beamsplitters have played an important role in quantum optics experiments. They are often used to split and combine two beams, especially in the construct of an interferometer. In this letter, we experimentally implement a nonlinear beamsplitter using a phase-sensitive parametric amplifier, which is based on four-wave mixing in hot rubidium vapor. Here we show that, despite the different frequencies of the two input beams, the output ports of the nonlinear beamsplitter exhibit interference phenomena. We make measurements of the interference fringe visibility and study how various parameters, such as the intensity gain of the amplifier, the intensity ratio of the two input beams, and the one and two photon detunings, affect the behavior of the nonlinear beamsplitter. It may find potential applications in quantum metrology and quantum information processing.

Housing price prediction: parametric versus semi-parametric spatial hedonic models

Science.gov (United States)

Montero, José-María; Mínguez, Román; Fernández-Avilés, Gema

2018-01-01

House price prediction is a hot topic in the economic literature. House price prediction has traditionally been approached using a-spatial linear (or intrinsically linear) hedonic models. It has been shown, however, that spatial effects are inherent in house pricing. This article considers parametric and semi-parametric spatial hedonic model variants that account for spatial autocorrelation, spatial heterogeneity and (smooth and nonparametrically specified) nonlinearities using penalized splines methodology. The models are represented as a mixed model that allow for the estimation of the smoothing parameters along with the other parameters of the model. To assess the out-of-sample performance of the models, the paper uses a database containing the price and characteristics of 10,512 homes in Madrid, Spain (Q1 2010). The results obtained suggest that the nonlinear models accounting for spatial heterogeneity and flexible nonlinear relationships between some of the individual or areal characteristics of the houses and their prices are the best strategies for house price prediction.

Parametric Instability in Advanced Laser Interferometer Gravitational Wave Detectors

International Nuclear Information System (INIS)

Ju, L; Grass, S; Zhao, C; Degallaix, J; Blair, D G

2006-01-01

High frequency parametric instabilities in optical cavities are radiation pressure induced interactions between test mass mechanical modes and cavity optical modes. The parametric gain depends on the cavity power and the quality factor of the test mass internal modes (usually in ultrasonic frequency range), as well as the overlap integral for the mechanical and optical modes. In advanced laser interferometers which require high optical power and very low acoustic loss test masses, parametric instabilities could prevent interferometer operation if not suppressed. Here we review the problem of parametric instabilities in advanced detector configurations for different combinations of sapphire and fused silica test masses, and compare three methods for control or suppression of parametric instabilities-thermal tuning, surface damping and active feedback

Entanglement in a parametric converter

Energy Technology Data Exchange (ETDEWEB)

Lee, Su-Yong; Qamar, Shahid; Lee, Hai-Woong; Zubairy, M Suhail [Center for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)], E-mail: shahid_qamar@pieas.edu.pk, E-mail: zubairy@physics.tamu.edu

2008-07-28

In this paper, we consider a parametric converter as a source of entangled radiation. We examine recently derived conditions (Hillery and Zubairy 2006 Phys. Rev. Lett. 96 050503, Duan et al 2000 Phys. Rev. Lett. 84 2722) for determining when the two output modes in a parametric converter are entangled. We show that for different initial field states, the two criteria give different conditions that ensure that the output states are entangled. We also present an input-output calculation for the entanglement of the output field.

Parametric Quadrilateral Meshes for the Design and Optimization of Superconducting Magnets

CERN Document Server

Aleksa, Martin; Völlinger, Christine

2002-01-01

The program package ROXIE has been developed at CERN for the design and optimization of accelerator magnets. The necessity of extremely uniform fields in the superconducting accelerator magnets for LHC requires very accurate methods of field computation. For this purpose the coupled boundary-element / finite-element technique (BEM-FEM) is used. Quadrilateral higher order finite-element meshes are generated for the discretization of the iron domain (yoke) and stainless steel collars. A new mesh generator using geometrically optimized domain decomposition which was developed at the University of Stuttgart, Germany has been implemented into the ROXIE program providing fully automatic and user friendly mesh generation. The structure of the magnet cross-section can be modeled using parametric objects such as holes of different forms, elliptic, parabolic or hyperbolic arcs, notches, slots, .... For sensitivity analysis and parametric studies, point based morphing algorithms are applied to guarantee smooth adaptatio...

Parametric resonance of intrinsic localized modes in coupled cantilever arrays

International Nuclear Information System (INIS)

Kimura, Masayuki; Matsushita, Yasuo; Hikihara, Takashi

2016-01-01

In this study, the parametric resonances of pinned intrinsic localized modes (ILMs) were investigated by computing the unstable regions in parameter space consisting of parametric excitation amplitude and frequency. In the unstable regions, the pinned ILMs were observed to lose stability and begin to fluctuate. A nonlinear Klein–Gordon, Fermi–Pasta–Ulam-like, and mixed lattices were investigated. The pinned ILMs, particularly in the mixed lattice, were destabilized by parametric resonances, which were determined by comparing the shapes of the unstable regions with those in the Mathieu differential equation. In addition, traveling ILMs could be generated by parametric excitation. - Highlights: • Destabilization of intrinsic localized modes (ILMs) by parametric excitation is investigated for FPU, NKG, and mixed lattices. • Frequency and amplitude of parametric excitation is determined based on characteristic multipliers of ILMs. • Unstable regions for the mixed lattice case show very similar shape to those of the Mathieu equation. • ILMs become unstable by causing parametric resonance.

Parametric resonance of intrinsic localized modes in coupled cantilever arrays

Energy Technology Data Exchange (ETDEWEB)

Kimura, Masayuki, E-mail: kimura.masayuki.8c@kyoto-u.ac.jp [Department of Electrical Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan); Matsushita, Yasuo [Advanced Mathematical Institute, Osaka City University, 3-3-138 Sughimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Hikihara, Takashi [Department of Electrical Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)

2016-08-19

In this study, the parametric resonances of pinned intrinsic localized modes (ILMs) were investigated by computing the unstable regions in parameter space consisting of parametric excitation amplitude and frequency. In the unstable regions, the pinned ILMs were observed to lose stability and begin to fluctuate. A nonlinear Klein–Gordon, Fermi–Pasta–Ulam-like, and mixed lattices were investigated. The pinned ILMs, particularly in the mixed lattice, were destabilized by parametric resonances, which were determined by comparing the shapes of the unstable regions with those in the Mathieu differential equation. In addition, traveling ILMs could be generated by parametric excitation. - Highlights: • Destabilization of intrinsic localized modes (ILMs) by parametric excitation is investigated for FPU, NKG, and mixed lattices. • Frequency and amplitude of parametric excitation is determined based on characteristic multipliers of ILMs. • Unstable regions for the mixed lattice case show very similar shape to those of the Mathieu equation. • ILMs become unstable by causing parametric resonance.

Linear Parametric Model Checking of Timed Automata

DEFF Research Database (Denmark)

Hune, Tohmas Seidelin; Romijn, Judi; Stoelinga, Mariëlle

2001-01-01

We present an extension of the model checker Uppaal capable of synthesize linear parameter constraints for the correctness of parametric timed automata. The symbolic representation of the (parametric) state-space is shown to be correct. A second contribution of this paper is the identication...... of a subclass of parametric timed automata (L/U automata), for which the emptiness problem is decidable, contrary to the full class where it is know to be undecidable. Also we present a number of lemmas enabling the verication eort to be reduced for L/U automata in some cases. We illustrate our approach...

Controlling flexible rotor vibrations using parametric excitation

Energy Technology Data Exchange (ETDEWEB)

Atepor, L, E-mail: katepor@yahoo.co [Department of Mechanical Engineering, University of Glasgow, G12 8QQ (United Kingdom)

2009-08-01

This paper presents both theoretical and experimental studies of an active vibration controller for vibration in a flexible rotor system. The paper shows that the vibration amplitude can be modified by introducing an axial parametric excitation. The perturbation method of multiple scales is used to solve the equations of motion. The steady-state responses, with and without the parametric excitation terms, is investigated. An experimental test machine uses a piezoelectric exciter mounted on the end of the shaft. The results show a reduction in the rotor response amplitude under principal parametric resonance, and some good correlation between theory and experiment.

Numerical modelling of the pump-to-signal relative intensity noise ...

Indian Academy of Sciences (India)

An accurate numerical model to investigate the pump-to-signal relative intensity noise (RIN) transfer in two-pump fibre optical parametric amplifiers (2-P FOPAs) for low modulation frequencies is presented. Compared to other models in the field, this model takes into account the fibre loss, pump depletion as well as the gain ...

MEMS digital parametric loudspeaker

KAUST Repository

Carreno, Armando Arpys Arevalo

2016-03-23

This paper reports on the design and fabrication of MEMS actuator arrays suitable for Digital Sound reconstruction and Parametric Directional Loudspeakers. Two distinct versions of the device were fabricated: one using the electrostatic principle actuation and the other one, the piezoelectric principle. Both versions used similar membrane dimensions, with a diameter of 500 μm. These devices are the smallest Micro-Machined Ultrasound Transducer (MUT) arrays that can be operated for both modes: Digital Sound Reconstruction and Parametric Loudspeaker. The chips consist of an array with 256 transducers, in a footprint of 12 mm by 12 mm. The total single chip size is: 2.3 cm by 2.3 cm, including the contact pads. © 2016 IEEE.

MEMS digital parametric loudspeaker

KAUST Repository

Carreno, Armando Arpys Arevalo; Castro, David; Conchouso Gonzalez, David; Kosel, Jü rgen; Foulds, Ian G.

2016-01-01

This paper reports on the design and fabrication of MEMS actuator arrays suitable for Digital Sound reconstruction and Parametric Directional Loudspeakers. Two distinct versions of the device were fabricated: one using the electrostatic principle actuation and the other one, the piezoelectric principle. Both versions used similar membrane dimensions, with a diameter of 500 μm. These devices are the smallest Micro-Machined Ultrasound Transducer (MUT) arrays that can be operated for both modes: Digital Sound Reconstruction and Parametric Loudspeaker. The chips consist of an array with 256 transducers, in a footprint of 12 mm by 12 mm. The total single chip size is: 2.3 cm by 2.3 cm, including the contact pads. © 2016 IEEE.

Interference of biphotons upon parametric down-conversion in the field of biharmonic pumping

International Nuclear Information System (INIS)

Zolotoverkh, I I

2014-01-01

We report theoretical investigation of interference of biphotons emitted upon type-II collinear parametric down-conversion in the case of biharmonic pumping. Interference occurs when an optical or electronic shutter is used as an amplitude modulator in the experimental scheme. The phase of the interference is shown to depend on the time interval between the instant the shutter is opened and the instant corresponding to the maximum pump intensity. The main parameter affecting the visibility of the interference pattern is a time interval during which the shutter is open. (nonlinear optical phenomena)

Chou-Yang model and PHI form factor

Energy Technology Data Exchange (ETDEWEB)

Fazal-e-Aleem; Saleem, M.; Rafique, M.

1988-03-01

By using the deduced differential cross-section data for PHIp elastic scattering at 175 GeV/c in the Chou-Yang model, the PHI form factor has been computed and parametrized. Then in conjunction with the proton form factor this form factor is used in the pristine Chou-Yang model to obtain differential cross-section data at Fermilab energies. The theoretical results agree with the experimental measurements, endorsing the conjecture that the hadronic form factor of neutral particle is proportional to its magnetic form factor.

Parametric resonance in neutrino oscillations in matter

Indian Academy of Sciences (India)

Neutrino oscillations in matter can exhibit a specific resonance enhancement - parametric resonance, which is different from the MSW resonance. Oscillations of atmospheric and solar neutrinos inside the earth can undergo parametric enhancement when neutrino trajectories cross the core of the earth. In this paper we ...

Moment stability for a predator–prey model with parametric dichotomous noises

International Nuclear Information System (INIS)

Jin Yan-Fei

2015-01-01

In this paper, we investigate the solution moment stability for a Harrison-type predator–prey model with parametric dichotomous noises. Using the Shapiro–Loginov formula, the equations for the first-order and second-order moments are obtained and the corresponding stable conditions are given. It is found that the solution moment stability depends on the noise intensity and correlation time of noise. The first-order and second-order moments become unstable with the decrease of correlation time. That is, the dichotomous noise can improve the solution moment stability with respect to Gaussian white noise. Finally, some numerical results are presented to verify the theoretical analyses. (paper)

Polariton condensation, superradiance and difference combination parametric resonance in mode-locked laser

Science.gov (United States)

Bagayev, S. N.; Arkhipov, R. M.; Arkhipov, M. V.; Egorov, V. S.; Chekhonin, I. A.; Chekhonin, M. A.

2017-11-01

The generation of the ring mode-locked laser containing resonant absorption medium in the cavity was investigated. It is shown that near the strong resonant absorption lines a condensation of polaritons arises. Intensive radiation looks like as superradiance in a medium without population inversion. We studied theoretically the microscopic mechanism of these phenomena. It was shown that in this system in absorbing medium a strong self-induced difference combination parametric resonance exists. Superradiance on polaritonic modes in the absorbing medium are due to the emergence of light-induced resonant polarization as a result of fast periodic nonadiabatic quantum jumps in the absorber.

Parametric Conversion Using Custom MOS Varactors

Directory of Open Access Journals (Sweden)

Iniewski Krzysztof (Kris

2006-01-01

Full Text Available The possible role of customized MOS varactors in amplification, mixing, and frequency control of future millimeter wave CMOS RFICs is outlined. First, the parametric conversion concept is revisited and discussed in terms of modern RF communications systems. Second, the modeling, design, and optimization of MOS varactors are reconsidered in the context of their central role in parametric circuits. Third, a balanced varactor structure is proposed for robust oscillator frequency control in the presence of large extrinsic noise expected in tightly integrated wireless communicators. Main points include the proposal of a subharmonic pumping scheme based on the MOS varactor, a nonequilibrium elastance-voltage model, optimal varactor layout suggestions, custom m-CMOS varactor design and measurement, device-level balanced varactor simulations, and parametric circuit evaluation based on measured device characteristics.

Parametric pendulum based wave energy converter

Science.gov (United States)

Yurchenko, Daniil; Alevras, Panagiotis

2018-01-01

The paper investigates the dynamics of a novel wave energy converter based on the parametrically excited pendulum. The herein developed concept of the parametric pendulum allows reducing the influence of the gravity force thereby significantly improving the device performance at a regular sea state, which could not be achieved in the earlier proposed original point-absorber design. The suggested design of a wave energy converter achieves a dominant rotational motion without any additional mechanisms, like a gearbox, or any active control involvement. Presented numerical results of deterministic and stochastic modeling clearly reflect the advantage of the proposed design. A set of experimental results confirms the numerical findings and validates the new design of a parametric pendulum based wave energy converter. Power harvesting potential of the novel device is also presented.

SPM analysis of parametric (R)-[11C]PK11195 binding images: plasma input versus reference tissue parametric methods.

Science.gov (United States)

Schuitemaker, Alie; van Berckel, Bart N M; Kropholler, Marc A; Veltman, Dick J; Scheltens, Philip; Jonker, Cees; Lammertsma, Adriaan A; Boellaard, Ronald

2007-05-01

(R)-[11C]PK11195 has been used for quantifying cerebral microglial activation in vivo. In previous studies, both plasma input and reference tissue methods have been used, usually in combination with a region of interest (ROI) approach. Definition of ROIs, however, can be labourious and prone to interobserver variation. In addition, results are only obtained for predefined areas and (unexpected) signals in undefined areas may be missed. On the other hand, standard pharmacokinetic models are too sensitive to noise to calculate (R)-[11C]PK11195 binding on a voxel-by-voxel basis. Linearised versions of both plasma input and reference tissue models have been described, and these are more suitable for parametric imaging. The purpose of this study was to compare the performance of these plasma input and reference tissue parametric methods on the outcome of statistical parametric mapping (SPM) analysis of (R)-[11C]PK11195 binding. Dynamic (R)-[11C]PK11195 PET scans with arterial blood sampling were performed in 7 younger and 11 elderly healthy subjects. Parametric images of volume of distribution (Vd) and binding potential (BP) were generated using linearised versions of plasma input (Logan) and reference tissue (Reference Parametric Mapping) models. Images were compared at the group level using SPM with a two-sample t-test per voxel, both with and without proportional scaling. Parametric BP images without scaling provided the most sensitive framework for determining differences in (R)-[11C]PK11195 binding between younger and elderly subjects. Vd images could only demonstrate differences in (R)-[11C]PK11195 binding when analysed with proportional scaling due to intersubject variation in K1/k2 (blood-brain barrier transport and non-specific binding).

A multiresolution spatial parametrization for the estimation of fossil-fuel carbon dioxide emissions via atmospheric inversions.

Energy Technology Data Exchange (ETDEWEB)

Ray, Jaideep; Lee, Jina; Lefantzi, Sophia; Yadav, Vineet [Carnegie Institution for Science, Stanford, CA; Michalak, Anna M. [Carnegie Institution for Science, Stanford, CA; van Bloemen Waanders, Bart Gustaaf [Sandia National Laboratories, Albuquerque, NM; McKenna, Sean Andrew [IBM Research, Mulhuddart, Dublin 15, Ireland

2013-04-01

The estimation of fossil-fuel CO2 emissions (ffCO2) from limited ground-based and satellite measurements of CO2 concentrations will form a key component of the monitoring of treaties aimed at the abatement of greenhouse gas emissions. To that end, we construct a multiresolution spatial parametrization for fossil-fuel CO2 emissions (ffCO2), to be used in atmospheric inversions. Such a parametrization does not currently exist. The parametrization uses wavelets to accurately capture the multiscale, nonstationary nature of ffCO2 emissions and employs proxies of human habitation, e.g., images of lights at night and maps of built-up areas to reduce the dimensionality of the multiresolution parametrization. The parametrization is used in a synthetic data inversion to test its suitability for use in atmospheric inverse problem. This linear inverse problem is predicated on observations of ffCO2 concentrations collected at measurement towers. We adapt a convex optimization technique, commonly used in the reconstruction of compressively sensed images, to perform sparse reconstruction of the time-variant ffCO2 emission field. We also borrow concepts from compressive sensing to impose boundary conditions i.e., to limit ffCO2 emissions within an irregularly shaped region (the United States, in our case). We find that the optimization algorithm performs a data-driven sparsification of the spatial parametrization and retains only of those wavelets whose weights could be estimated from the observations. Further, our method for the imposition of boundary conditions leads to a 10computational saving over conventional means of doing so. We conclude with a discussion of the accuracy of the estimated emissions and the suitability of the spatial parametrization for use in inverse problems with a significant degree of regularization.

Testing the Weak Form Efficiency of Karachi Stock Exchange

Directory of Open Access Journals (Sweden)

Muhammad Arshad Haroon

2012-12-01

Full Text Available In an efficient market, share prices reflect all available information. The study of efficient market hypothesis helps to take right decisions related to investments. In this research,weak form efficiency has been tested of Karachi Stock Exchange—KSE covering the period of 2nd November 1991 to 2nd November 2011. Descriptive statistics indicated the absence of weak form efficiency while results of non-parametric tests, showed consistency as well. We employed non-parametric tests were KS Goodness-of-Fit test,run test and autocorrelation test to find out serial independency of the data. Results prove that KSE is not weak-form-efficient. This happens because KSE is an emerging market and there, it has been observed that information take time to be processed. Thus it can besaid that technical analysis may be applied to gain abnormal returns.

Two-parametric PT-symmetric quartic family

International Nuclear Information System (INIS)

Eremenko, Alexandre; Gabrielov, Andrei

2012-01-01

We describe a parametrization of the real spectral locus of the two-parametric family of PT-symmetric quartic oscillators. For this family, we find a parameter region where all eigenvalues are real, extending the results of Dorey et al (2007 J. Phys. A: Math Theor. 40 R205–83) and Shin (2005 J. Phys. A: Math. Gen. 38 6147–66; 2002 Commun. Math. Phys. 229 543–64). (paper)

A soft double regularization approach to parametric blind image deconvolution.

Science.gov (United States)

Chen, Li; Yap, Kim-Hui

2005-05-01

This paper proposes a blind image deconvolution scheme based on soft integration of parametric blur structures. Conventional blind image deconvolution methods encounter a difficult dilemma of either imposing stringent and inflexible preconditions on the problem formulation or experiencing poor restoration results due to lack of information. This paper attempts to address this issue by assessing the relevance of parametric blur information, and incorporating the knowledge into the parametric double regularization (PDR) scheme. The PDR method assumes that the actual blur satisfies up to a certain degree of parametric structure, as there are many well-known parametric blurs in practical applications. Further, it can be tailored flexibly to include other blur types if some prior parametric knowledge of the blur is available. A manifold soft parametric modeling technique is proposed to generate the blur manifolds, and estimate the fuzzy blur structure. The PDR scheme involves the development of the meaningful cost function, the estimation of blur support and structure, and the optimization of the cost function. Experimental results show that it is effective in restoring degraded images under different environments.

Parametric effects on glass reaction in the unsaturated test method

International Nuclear Information System (INIS)

Woodland, A.B.; Bates, J.K.; Gerding, T.J.

1991-12-01

The Unsaturated Test Method has been applied to study glass reaction under conditions that may be present at the potential Yucca Mountain site, currently under evaluation for storage of reprocessed high-level nuclear waste. The results from five separate sets of parametric experiments are presented wherein test parameters ranging from water contact volume to sensitization of metal in contact with the glass were examined. The most significant effect was observed when the volume of water, as controlled by the water inject volume and interval period, was such to allow exfoliation of reacted glass to occur. The extent of reaction was also influenced to a lesser extent by the degree of sensitization of the 304L stainless steel. For each experiment, the release of cations from the glass and alteration of the glass were examined. The major alteration product is a smectite clay that forms both from precipitation from solution and from in-situ alteration of the glass itself. It is this clay that undergoes exfoliation as water drips from the glass. A comparison is made between the results of the parametric experiments with those of static leach tests. In the static tests the rates of release become progressively reduced through 39 weeks while, in contrast, they remain relatively constant in the parametric experiments for at least 300 weeks. This differing behavior may be attributable to the dripping water environment where fresh water is periodically added and where evaporation can occur

Incorporating Oxygen-Enhanced MRI into Multi-Parametric Assessment of Human Prostate Cancer

Directory of Open Access Journals (Sweden)

Heling Zhou

2017-08-01

Full Text Available Hypoxia is associated with prostate tumor aggressiveness, local recurrence, and biochemical failure. Magnetic resonance imaging (MRI offers insight into tumor pathophysiology and recent reports have related transverse relaxation rate (R2* and longitudinal relaxation rate (R1 measurements to tumor hypoxia. We have investigated the inclusion of oxygen-enhanced MRI for multi-parametric evaluation of tumor malignancy. Multi-parametric MRI sequences at 3 Tesla were evaluated in 10 patients to investigate hypoxia in prostate cancer prior to radical prostatectomy. Blood oxygen level dependent (BOLD, tissue oxygen level dependent (TOLD, dynamic contrast enhanced (DCE, and diffusion weighted imaging MRI were intercorrelated and compared with the Gleason score. The apparent diffusion coefficient (ADC was significantly lower in tumor than normal prostate. Baseline R2* (BOLD-contrast was significantly higher in tumor than normal prostate. Upon the oxygen breathing challenge, R2* decreased significantly in the tumor tissue, suggesting improved vascular oxygenation, however changes in R1 were minimal. R2* of contralateral normal prostate decreased in most cases upon oxygen challenge, although the differences were not significant. Moderate correlation was found between ADC and Gleason score. ADC and R2* were correlated and trends were found between Gleason score and R2*, as well as maximum-intensity-projection and area-under-the-curve calculated from DCE. Tumor ADC and R2* have been associated with tumor hypoxia, and thus the correlations are of particular interest. A multi-parametric approach including oxygen-enhanced MRI is feasible and promises further insights into the pathophysiological information of tumor microenvironment.

Detection of two-mode compression and degree of entanglement in continuous variables in parametric scattering of light

International Nuclear Information System (INIS)

Rytikov, G. O.; Chekhova, M. V.

2008-01-01

Generation of 'twin beams' (of light with two-mode compression) in single-pass optical parametric amplifier (a crystal with a nonzero quadratic susceptibility) is considered. Radiation at the output of the nonlinear crystal is essentially multimode, which raises the question about the effect of the detection volume on the extent of suppression of noise from the difference photocurrent of the detectors. In addition, the longitudinal as well as transverse size of the region in which parametric transformation takes place is of fundamental importance. It is shown that maximal suppression of noise from difference photocurrent requires a high degree of entanglement of two-photon light at the outlet of the parametric amplifier, which is defined by Federov et al. [Phys. Rev. A 77, 032336 (2008)] as the ratio of the intensity distribution width to the correlation function width. The detection volume should be chosen taking into account both these quantities. Various modes of single-pass generation of twin beams (noncollinear frequency-degenerate and collinear frequency-nondegenerate synchronism of type I, as well as collinear frequency-degenerate synchronism of type II) are considered in connection with the degree of entanglement

Performance of MgO:PPLN, KTA, and KNbO₃ for mid-wave infrared broadband parametric amplification at high average power.

Science.gov (United States)

Baudisch, M; Hemmer, M; Pires, H; Biegert, J

2014-10-15

The performance of potassium niobate (KNbO₃), MgO-doped periodically poled lithium niobate (MgO:PPLN), and potassium titanyl arsenate (KTA) were experimentally compared for broadband mid-wave infrared parametric amplification at a high repetition rate. The seed pulses, with an energy of 6.5 μJ, were amplified using 410 μJ pump energy at 1064 nm to a maximum pulse energy of 28.9 μJ at 3 μm wavelength and at a 160 kHz repetition rate in MgO:PPLN while supporting a transform limited duration of 73 fs. The high average powers of the interacting beams used in this study revealed average power-induced processes that limit the scaling of optical parametric amplification in MgO:PPLN; the pump peak intensity was limited to 3.8  GW/cm² due to nonpermanent beam reshaping, whereas in KNbO₃ an absorption-induced temperature gradient in the crystal led to permanent internal distortions in the crystal structure when operated above a pump peak intensity of 14.4  GW/cm².

The parametrized simulation of electromagnetic showers

International Nuclear Information System (INIS)

Peters, S.

1992-09-01

The simulation of electromagnetic showers in calorimeters by detailed tracking of all secondary particles is extremely computer time consuming. Without loosing considerably in precision, the use of parametrizations for global shower properties may reduce the computing time by factors of 10 1 to 10 4 , depending on the energy, the degree of parametrization, and the complexity in the material description and the cut off energies in the detailed simulation. To arrive at a high degree of universality, parametrizations of individual electromagnetic showers in homogeneous media are developed, taking the dependence of the shower development on the material into account. In sampling calorimeters, the inhomogeneous material distribution leads to additional effects which can be taken into account by geometry dependent terms in the parametrization of the longitudinal and radial energy density distributions. Comparisons with detailed simulations of homogeneous and sampling calorimeters show very good agreement in the fluctuations, correlations, and signal averages of spatial energy distributions. Verifications of the algorithms for the simulation of the H1 detector are performed using calorimeter test data for different moduls of the H1 liquid argon calorimeter. Special attention has been paid to electron pion separation, which is of great importance for physics analysis. (orig.) [de

GHz-rate optical parametric amplifier in hydrogenated amorphous silicon

International Nuclear Information System (INIS)

Wang, Ke-Yao; Foster, Amy C

2015-01-01

We demonstrate optical parametric amplification operating at GHz-rates at telecommunications wavelengths using a hydrogenated amorphous silicon waveguide through the nonlinear optical process of four-wave mixing. We investigate how the parametric amplification scales with repetition rate. The ability to achieve amplification at GHz-repetition rates shows hydrogenated amorphous silicon’s potential for telecommunication applications and a GHz-rate optical parametric oscillator. (paper)

MTL-Model Checking of One-Clock Parametric Timed Automata is Undecidable

Directory of Open Access Journals (Sweden)

Karin Quaas

2014-03-01

Full Text Available Parametric timed automata extend timed automata (Alur and Dill, 1991 in that they allow the specification of parametric bounds on the clock values. Since their introduction in 1993 by Alur, Henzinger, and Vardi, it is known that the emptiness problem for parametric timed automata with one clock is decidable, whereas it is undecidable if the automaton uses three or more parametric clocks. The problem is open for parametric timed automata with two parametric clocks. Metric temporal logic, MTL for short, is a widely used specification language for real-time systems. MTL-model checking of timed automata is decidable, no matter how many clocks are used in the timed automaton. In this paper, we prove that MTL-model checking for parametric timed automata is undecidable, even if the automaton uses only one clock and one parameter and is deterministic.

Parametric Audio Based Decoder and Music Synthesizer for Mobile Applications

NARCIS (Netherlands)

Oomen, A.W.J.; Szczerba, M.Z.; Therssen, D.

2011-01-01

This paper reviews parametric audio coders and discusses novel technologies introduced in a low-complexity, low-power consumption audiodecoder and music synthesizer platform developed by the authors. Thedecoder uses parametric coding scheme based on the MPEG-4 Parametric Audio standard. In order to

Parametrization of the nucleon-trinucleon overlap function in 4He and the effect of meson exchange corrections

International Nuclear Information System (INIS)

Greben, J.M.

1982-04-01

Nucleon-trinucleon overlap functions in 4 He have been parametrized as a sum of exponentials, and are fitted to the charge form factor of 4 He. We present results with and without taking account of meson-exchange corrections

Parametric resonance in an expanding universe

International Nuclear Information System (INIS)

Zlatev, I.; Huey, G.; Steinhardt, P.J.

1998-01-01

Parametric resonance has been discussed as a mechanism for copious particle production following inflation. Here we present a simple and intuitive calculational method for estimating the efficiency of parametric amplification as a function of parameters. This is important for determining whether resonant amplification plays an important role in the reheating process. We find that significant amplification occurs only for a limited range of couplings and interactions. copyright 1998 The American Physical Society

Parametric boundary reconstruction algorithm for industrial CT metrology application.

Science.gov (United States)

Yin, Zhye; Khare, Kedar; De Man, Bruno

2009-01-01

High-energy X-ray computed tomography (CT) systems have been recently used to produce high-resolution images in various nondestructive testing and evaluation (NDT/NDE) applications. The accuracy of the dimensional information extracted from CT images is rapidly approaching the accuracy achieved with a coordinate measuring machine (CMM), the conventional approach to acquire the metrology information directly. On the other hand, CT systems generate the sinogram which is transformed mathematically to the pixel-based images. The dimensional information of the scanned object is extracted later by performing edge detection on reconstructed CT images. The dimensional accuracy of this approach is limited by the grid size of the pixel-based representation of CT images since the edge detection is performed on the pixel grid. Moreover, reconstructed CT images usually display various artifacts due to the underlying physical process and resulting object boundaries from the edge detection fail to represent the true boundaries of the scanned object. In this paper, a novel algorithm to reconstruct the boundaries of an object with uniform material composition and uniform density is presented. There are three major benefits in the proposed approach. First, since the boundary parameters are reconstructed instead of image pixels, the complexity of the reconstruction algorithm is significantly reduced. The iterative approach, which can be computationally intensive, will be practical with the parametric boundary reconstruction. Second, the object of interest in metrology can be represented more directly and accurately by the boundary parameters instead of the image pixels. By eliminating the extra edge detection step, the overall dimensional accuracy and process time can be improved. Third, since the parametric reconstruction approach shares the boundary representation with other conventional metrology modalities such as CMM, boundary information from other modalities can be directly

650-nJ pulses from a cavity-dumped Yb:fiber-pumped ultrafast optical parametric oscillator

Science.gov (United States)

Lamour, Tobias P.; Reid, Derryck T.

2011-08-01

Sub-250-fs pulses with energies of up to 650 nJ and peak powers up to 2.07 MW were generated from a cavity-dumped optical parametric oscillator, synchronously-pumped at 15.3 MHz with sub-400-fs pulses from an Yb:fiber laser. The average beam quality factor of the dumped output was M2 ~1.2 and the total relative-intensity noise was 8 mdBc, making the system a promising candidate for ultrafast laser inscription of infrared materials.

Controlling Parametric Resonance

DEFF Research Database (Denmark)

Galeazzi, Roberto; Pettersen, Kristin Ytterstad

2012-01-01

the authors review the conditions for the onset of parametric resonance, and propose a nonlinear control strategy in order to both induce the resonant oscillations and to stabilize the unstable motion. Lagrange’s theory is used to derive the dynamics of the system and input–output feedback linearization...

'J-KAREN' - high intensity, high contrast laser

International Nuclear Information System (INIS)

Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Okada, Hajime; Sasao, Hajime; Sagisaka, Akito; Ochi, Yoshihiro; Tanaka, Momoko; Kondo, Kiminori; Tateno, Ryo; Sugiyama, Akira; Daido, Hiroyuki; Koike, Masato; Kawanishi, Syunichi; Shimomura, Takuya; Tanoue, Manabu; Wakai, Daisuke; Kondo, Shuji; Kanazawa, Shuhei

2010-01-01

We report on the high intensity, high contrast double chirped-pulse amplification (CPA) Ti:sapphire laser system (named J-KAREN). By use of an optical parametric chirped-pulse amplification (OPCPA) preamplifier that is seeded by a cleaned high-energy pulse, a background amplified spontaneous emission (ASE) level of 10 -10 relative to the peak main femtosecond pulse on the picosecond timescales demonstrated with an output energy of 1.7 J and a pulse duration of 30 fs, corresponding to a peak power of 60TW at a 10 Hz repetition rate. This system which uses a cryogenically-cooled Ti:sapphire final amplifier generates focused peak intensity in excess of 10 20 W/cm 2 at a 10 Hz repetition rate. (author)

Synchronization of chaos in non-identical parametrically excited systems

International Nuclear Information System (INIS)

Idowu, B.A.; Vincent, U.E.; Njah, A.N.

2009-01-01

In this paper, we investigate the synchronization of chaotic systems consisting of non-identical parametrically excited oscillators. The active control technique is employed to design control functions based on Lyapunov stability theory and Routh-Hurwitz criteria so as to achieve global chaos synchronization between a parametrically excited gyroscope and each of the parametrically excited pendulum and Duffing oscillator. Numerical simulations are implemented to verify the results.

Incorporating parametric uncertainty into population viability analysis models

Science.gov (United States)

McGowan, Conor P.; Runge, Michael C.; Larson, Michael A.

2011-01-01

Uncertainty in parameter estimates from sampling variation or expert judgment can introduce substantial uncertainty into ecological predictions based on those estimates. However, in standard population viability analyses, one of the most widely used tools for managing plant, fish and wildlife populations, parametric uncertainty is often ignored in or discarded from model projections. We present a method for explicitly incorporating this source of uncertainty into population models to fully account for risk in management and decision contexts. Our method involves a two-step simulation process where parametric uncertainty is incorporated into the replication loop of the model and temporal variance is incorporated into the loop for time steps in the model. Using the piping plover, a federally threatened shorebird in the USA and Canada, as an example, we compare abundance projections and extinction probabilities from simulations that exclude and include parametric uncertainty. Although final abundance was very low for all sets of simulations, estimated extinction risk was much greater for the simulation that incorporated parametric uncertainty in the replication loop. Decisions about species conservation (e.g., listing, delisting, and jeopardy) might differ greatly depending on the treatment of parametric uncertainty in population models.

Sensitivity of Technical Efficiency Estimates to Estimation Methods: An Empirical Comparison of Parametric and Non-Parametric Approaches

OpenAIRE

de-Graft Acquah, Henry

2014-01-01

This paper highlights the sensitivity of technical efficiency estimates to estimation approaches using empirical data. Firm specific technical efficiency and mean technical efficiency are estimated using the non parametric Data Envelope Analysis (DEA) and the parametric Corrected Ordinary Least Squares (COLS) and Stochastic Frontier Analysis (SFA) approaches. Mean technical efficiency is found to be sensitive to the choice of estimation technique. Analysis of variance and Tukey’s test sugge...

Parametric roll resonance monitoring using signal-based detection

DEFF Research Database (Denmark)

Galeazzi, Roberto; Blanke, Mogens; Falkenberg, Thomas

2015-01-01

Extreme roll motion of ships can be caused by several phenomena, one of which is parametric roll resonance. Several incidents occurred unexpectedly around the millennium and caused vast fiscal losses on large container vessels. The phenomenon is now well understood and some consider parametric roll...... algorithms in real conditions, and to evaluate the frequency of parametric roll events on the selected vessels. Detection performance is scrutinised through the validation of the detected events using owners’ standard methods, and supported by available wave radar data. Further, a bivariate statistical...... analysis of the outcome of the signal-based detectors is performed to assess the real life false alarm probability. It is shown that detection robustness and very low false warning rates are obtained. The study concludes that small parametric roll events are occurring, and that the proposed signal...

Analytic calculation of radio emission from parametrized extensive air showers: A tool to extract shower parameters

Science.gov (United States)

Scholten, O.; Trinh, T. N. G.; de Vries, K. D.; Hare, B. M.

2018-01-01

The radio intensity and polarization footprint of a cosmic-ray induced extensive air shower is determined by the time-dependent structure of the current distribution residing in the plasma cloud at the shower front. In turn, the time dependence of the integrated charge-current distribution in the plasma cloud, the longitudinal shower structure, is determined by interesting physics which one would like to extract, such as the location and multiplicity of the primary cosmic-ray collision or the values of electric fields in the atmosphere during thunderstorms. To extract the structure of a shower from its footprint requires solving a complicated inverse problem. For this purpose we have developed a code that semianalytically calculates the radio footprint of an extensive air shower given an arbitrary longitudinal structure. This code can be used in an optimization procedure to extract the optimal longitudinal shower structure given a radio footprint. On the basis of air-shower universality we propose a simple parametrization of the structure of the plasma cloud. This parametrization is based on the results of Monte Carlo shower simulations. Deriving the parametrization also teaches which aspects of the plasma cloud are important for understanding the features seen in the radio-emission footprint. The calculated radio footprints are compared with microscopic CoREAS simulations.

Parametric resonance and cooling on an atom chip

International Nuclear Information System (INIS)

Yan Bo; Li Xiaolin; Ke Min; Wang Yuzhu

2008-01-01

This paper observes the parametric excitation on atom chip by measuring the trap loss when applying a parametric modulation. By modulating the current in chip wires, it modulates not only the trap frequency but also the trap position. It shows that the strongest resonance occurs when the modulation frequency equals to the trap frequency. The resonance amplitude increases exponentially with modulation depth. Because the Z-trap is an anharmonic trap, there exists energy selective excitation which would cause parametric cooling. We confirm this effect by observing the temperature of atom cloud dropping

On the parametric approximation in quantum optics

Energy Technology Data Exchange (ETDEWEB)

D' Ariano, G.M.; Paris, M.G.A.; Sacchi, M.F. [Istituto Nazionale di Fisica Nucleare, Pavia (Italy); Pavia Univ. (Italy). Dipt. di Fisica ' Alessandro Volta'

1999-03-01

The authors perform the exact numerical diagonalization of Hamiltonians that describe both degenerate and nondegenerate parametric amplifiers, by exploiting the conservation laws pertaining each device. It is clarify the conditions under which the parametric approximation holds, showing that the most relevant requirements is the coherence of the pump after the interaction, rather than its un depletion.

On the parametric approximation in quantum optics

International Nuclear Information System (INIS)

D'Ariano, G.M.; Paris, M.G.A.; Sacchi, M.F.; Pavia Univ.

1999-01-01

The authors perform the exact numerical diagonalization of Hamiltonians that describe both degenerate and nondegenerate parametric amplifiers, by exploiting the conservation laws pertaining each device. It is clarify the conditions under which the parametric approximation holds, showing that the most relevant requirements is the coherence of the pump after the interaction, rather than its un depletion

Piezoelectric energy harvesting with parametric uncertainty

International Nuclear Information System (INIS)

Ali, S F; Friswell, M I; Adhikari, S

2010-01-01

The design and analysis of energy harvesting devices is becoming increasing important in recent years. Most of the literature has focused on the deterministic analysis of these systems and the problem of uncertain parameters has received less attention. Energy harvesting devices exhibit parametric uncertainty due to errors in measurement, errors in modelling and variability in the parameters during manufacture. This paper investigates the effect of parametric uncertainty in the mechanical system on the harvested power, and derives approximate explicit formulae for the optimal electrical parameters that maximize the mean harvested power. The maximum of the mean harvested power decreases with increasing uncertainty, and the optimal frequency at which the maximum mean power occurs shifts. The effect of the parameter variance on the optimal electrical time constant and optimal coupling coefficient are reported. Monte Carlo based simulation results are used to further analyse the system under parametric uncertainty

Pump-To-Signal Intensity Modulation Transfer Characteristics in FOPAs: Modulation Frequency and Saturation Effect

DEFF Research Database (Denmark)

Lali-Dastjerdi, Zohreh; Cristofori, Valentina; Lund-Hansen, Toke

2012-01-01

This paper reports a comprehensive study of pump- to-signal intensity modulation transfer (IMT) in single-pump fiber optic parametric amplifiers (FOPAs). In particular, the IMT is studied for the first time for high-frequency fluctuations of the pump as well as in the saturated gain regime. The IMT...... cut-off frequency in typical single-pump FOPAs is around 100–200 GHz. The possibilities to shift this frequency based on dispersion and nonlinearities involved in the parametric gain are discussed. The severe IMT to the signal at low modulation frequencies can be suppressed by more than 50...

Moment stability for a predator-prey model with parametric dichotomous noises

Science.gov (United States)

Jin, Yan-Fei

2015-06-01

In this paper, we investigate the solution moment stability for a Harrison-type predator-prey model with parametric dichotomous noises. Using the Shapiro-Loginov formula, the equations for the first-order and second-order moments are obtained and the corresponding stable conditions are given. It is found that the solution moment stability depends on the noise intensity and correlation time of noise. The first-order and second-order moments become unstable with the decrease of correlation time. That is, the dichotomous noise can improve the solution moment stability with respect to Gaussian white noise. Finally, some numerical results are presented to verify the theoretical analyses. Project supported by the National Natural Science Foundation of China (Grant No. 11272051).

Design and development of a parametrically excited nonlinear energy harvester

International Nuclear Information System (INIS)

Yildirim, Tanju; Ghayesh, Mergen H.; Li, Weihua; Alici, Gursel

2016-01-01

Highlights: • A parametrically broadband energy harvester was fabricated. • Strong softening-type nonlinear behaviour was observed. • Experiments were conducted showing the large bandwidth of the device. - Abstract: An energy harvester has been designed, fabricated and tested based on the nonlinear dynamical response of a parametrically excited clamped-clamped beam with a central point-mass; magnets have been used as the central point-mass which pass through a coil when parametrically excited. Experiments have been conducted for the energy harvester when the system is excited (i) harmonically near the primary resonance; (ii) harmonically near the principal parametric resonance; (iii) by means of a non-smooth periodic excitation. An electrodynamic shaker was used to parametrically excite the system and the corresponding displacement of the magnet and output voltages of the coil were measured. It has been shown that the system displays linear behaviour at the primary resonance; however, at the principal parametric resonance, the motion characteristic of the magnet substantially changed displaying a strong softening-type nonlinearity. Theoretical simulations have also been conducted in order to verify the experimental results; the comparison between theory and experiment were within very good agreement of each other. The energy harvester developed in this paper is capable of harvesting energy close to the primary resonance as well as the principal parametric resonance; the frequency-band has been broadened significantly mainly due to the nonlinear effects as well as the parametric excitation.

Parametric Fires for Structural Design

DEFF Research Database (Denmark)

Hertz, Kristian

2012-01-01

The authorities, the construction association, and a number of companies in Denmark have supported the author writing a guide for design of building structures for parametric fires. The guide is published by the ministry as a supplement to the building regulations. However, consultants and contra......The authorities, the construction association, and a number of companies in Denmark have supported the author writing a guide for design of building structures for parametric fires. The guide is published by the ministry as a supplement to the building regulations. However, consultants...... and contractors have asked for a reference in English in order to make the guide-lines and the background for them available internationally. The paper therefore presents recommendations from the design guide especially concerning how to assess parametric design fires based on the opening factor method for large...... compartments. Findings leading to the guide-lines are discussed, and it is indicated what a safe design fire model means for structural design and how it differs from a safe design fire model for evacuation. Furthermore, the paper includes some experiences from the application of the design guide in practise...

Observation of Parametric Instability in Advanced LIGO.

Science.gov (United States)

Evans, Matthew; Gras, Slawek; Fritschel, Peter; Miller, John; Barsotti, Lisa; Martynov, Denis; Brooks, Aidan; Coyne, Dennis; Abbott, Rich; Adhikari, Rana X; Arai, Koji; Bork, Rolf; Kells, Bill; Rollins, Jameson; Smith-Lefebvre, Nicolas; Vajente, Gabriele; Yamamoto, Hiroaki; Adams, Carl; Aston, Stuart; Betzweiser, Joseph; Frolov, Valera; Mullavey, Adam; Pele, Arnaud; Romie, Janeen; Thomas, Michael; Thorne, Keith; Dwyer, Sheila; Izumi, Kiwamu; Kawabe, Keita; Sigg, Daniel; Derosa, Ryan; Effler, Anamaria; Kokeyama, Keiko; Ballmer, Stefan; Massinger, Thomas J; Staley, Alexa; Heinze, Matthew; Mueller, Chris; Grote, Hartmut; Ward, Robert; King, Eleanor; Blair, David; Ju, Li; Zhao, Chunnong

2015-04-24

Parametric instabilities have long been studied as a potentially limiting effect in high-power interferometric gravitational wave detectors. Until now, however, these instabilities have never been observed in a kilometer-scale interferometer. In this Letter, we describe the first observation of parametric instability in a gravitational wave detector, and the means by which it has been removed as a barrier to progress.

Observational Signatures of Parametric Instability at 1AU

Science.gov (United States)

Bowen, T. A.; Bale, S. D.; Badman, S.

2017-12-01

Observations and simulations of inertial compressive turbulence in the solar wind are characterized by density structures anti-correlated with magnetic fluctuations parallel to the mean field. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures (PBS), kinetic ion acoustic waves, as well as the MHD slow mode. Recent work, specifically Verscharen et al. (2017), has highlighted the unexpected fluid like nature of the solar wind. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggests the presence of a driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the parametric instability, in which large amplitude Alfvenic fluctuations decay into parallel propagating compressive waves. This work employs 10 years of WIND observations in order to test the parametric decay process as a source of compressive waves in the solar wind through comparing collisionless damping rates of compressive fluctuations with growth rates of the parametric instability. Preliminary results suggest that generation of compressive waves through parametric decay is overdamped at 1 AU. However, the higher parametric decay rates expected in the inner heliosphere likely allow for growth of the slow mode-the remnants of which could explain density fluctuations observed at 1AU.

Magnetorheological fluid dampers: a review of parametric modelling

International Nuclear Information System (INIS)

Wang, D H; Liao, W H

2011-01-01

Due to the inherent nonlinear nature of magnetorheological (MR) dampers, one of the challenging aspects for developing and utilizing these devices to achieve high performance is the development of models that can accurately describe their unique characteristics. In this review, the characteristics of MR dampers are summarized according to the measured responses under different conditions. On these bases, the considerations and methods of the parametric dynamic modelling for MR dampers are given and the state-of-the-art parametric dynamic modelling, identification and validation techniques for MR dampers are reviewed. In the past two decades, the models for MR dampers have been focused on how to improve the modelling accuracy. Although the force–displacement behaviour is well represented by most of the proposed dynamic models for MR dampers, no simple parametric models with high accuracy for MR dampers can be found. In addition, the parametric dynamic models for MR dampers with on-line updating ability and the inverse parametric models for MR dampers are scarcely explored. Moreover, whether one dynamic model for MR dampers can portray the force–displacement and force–velocity behaviour is not only determined by the dynamic model itself but also determined by the identification method. (topical review)

A capacitive ultrasonic transducer based on parametric resonance

Science.gov (United States)

Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F.

2017-07-01

A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of fo. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2fo with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at fo frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.

Multi-level approach for parametric roll analysis

Science.gov (United States)

Kim, Taeyoung; Kim, Yonghwan

2011-03-01

The present study considers multi-level approach for the analysis of parametric roll phenomena. Three kinds of computation method, GM variation, impulse response function (IRF), and Rankine panel method, are applied for the multi-level approach. IRF and Rankine panel method are based on the weakly nonlinear formulation which includes nonlinear Froude- Krylov and restoring forces. In the computation result of parametric roll occurrence test in regular waves, IRF and Rankine panel method show similar tendency. Although the GM variation approach predicts the occurrence of parametric roll at twice roll natural frequency, its frequency criteria shows a little difference. Nonlinear roll motion in bichromatic wave is also considered in this study. To prove the unstable roll motion in bichromatic waves, theoretical and numerical approaches are applied. The occurrence of parametric roll is theoretically examined by introducing the quasi-periodic Mathieu equation. Instability criteria are well predicted from stability analysis in theoretical approach. From the Fourier analysis, it has been verified that difference-frequency effects create the unstable roll motion. The occurrence of unstable roll motion in bichromatic wave is also observed in the experiment.

Low Parametric Sensitivity Realizations with relaxed L2-dynamic-range-scaling constraints

OpenAIRE

Hilaire , Thibault

2009-01-01

This paper presents a new dynamic-range scaling for the implementation of filters/controllers in state-space form. Relaxing the classical L2-scaling constraints by specific fixed-point considerations allows for a higher degree of freedom for the optimal L2-parametric sensitivity problem. However, overflows in the implementation are still prevented. The underlying constrained problem is converted into an unconstrained problem for which a solution can be provided. This leads to realizations whi...

Performance Analysis Of Single-Pumped And Dual-Pumped Parametric Optical Amplifier

Directory of Open Access Journals (Sweden)

Sandar Myint

2015-06-01

Full Text Available Abstract In this study we present a performance analysis of single-pumped and dual- pumped parametric optical amplifier and present the analysis of gain flatness in dual- pumped Fiber Optical Parametric Amplifier FOPA based on four-wave mixing FWM. Result shows that changing the signal power and pump power give the various gains in FOPA. It is also found out that the parametric gain increase with increase in pump power and decrease in signal power. .Moreover in this paper the phase matching condition in FWM plays a vital role in predicting the gain profile of the FOPAbecause the parametric gain is maximum when the total phase mismatch is zero.In this paper single-pumped parametric amplification over a 50nm gain bandwidth is demonstrated using 500 nm highly nonlinear fiber HNLF and signal achieves about 31dB gain. For dual-pumped parametric amplification signal achieves 26.5dB gains over a 50nm gain bandwidth. Therefore dual-pumped parametric amplifier can provide relatively flat gain over a much wider bandwidth than the single-pumped FOPA.

Parametric Explosion Spectral Model

Energy Technology Data Exchange (ETDEWEB)

Ford, S R; Walter, W R

2012-01-19

Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.

Assessment of left ventricular contraction by parametric analysis of main motion (PAMM): theory and application for echocardiography

International Nuclear Information System (INIS)

Dominguez, C Ruiz; Kachenoura, N; Cesare, A De; Delouche, A; Lim, P; Gerard, O; Herment, A; Diebold, B; Frouin, F

2005-01-01

The computerized study of the regional contraction of the left ventricle has undergone numerous developments, particularly in relation to echocardiography. A new method, parametric analysis of main motion (PAMM), is proposed in order to synthesize the information contained in a cine loop of images in parametric images. PAMM determines, for the intensity variation time curves (IVTC) observed in each pixel, two amplitude coefficients characterizing the continuous component and the alternating component; the variable component is generated from a mother curve by introducing a time shift coefficient and a scale coefficient. Two approaches, a PAMM data driven and a PAMM model driven (simpler and faster), are proposed. On the basis of the four coefficients, an amplitude image and an image of mean contraction time are synthesized and interpreted by a cardiologist. In all cases, both PAMM methods allow better IVTC adjustment than the other methods of parametric imaging used in echocardiography. A preliminary database comprising 70 segments is scored and compared with the visual analysis, taken from a consensus of two expert interpreters. The levels of absolute and relative concordance are 79% and 97%. PAMM model driven is a promising method for the rapid detection of abnormalities in left ventricle contraction

Crossing statistic: Bayesian interpretation, model selection and resolving dark energy parametrization problem

International Nuclear Information System (INIS)

Shafieloo, Arman

2012-01-01

By introducing Crossing functions and hyper-parameters I show that the Bayesian interpretation of the Crossing Statistics [1] can be used trivially for the purpose of model selection among cosmological models. In this approach to falsify a cosmological model there is no need to compare it with other models or assume any particular form of parametrization for the cosmological quantities like luminosity distance, Hubble parameter or equation of state of dark energy. Instead, hyper-parameters of Crossing functions perform as discriminators between correct and wrong models. Using this approach one can falsify any assumed cosmological model without putting priors on the underlying actual model of the universe and its parameters, hence the issue of dark energy parametrization is resolved. It will be also shown that the sensitivity of the method to the intrinsic dispersion of the data is small that is another important characteristic of the method in testing cosmological models dealing with data with high uncertainties

Physiological responses at short distances from a parametric speaker

Directory of Open Access Journals (Sweden)

Lee Soomin

2012-06-01

Full Text Available Abstract In recent years, parametric speakers have been used in various circumstances. In our previous studies, we verified that the physiological burden of the sound of parametric speaker set at 2.6 m from the subjects was lower than that of the general speaker. However, nothing has yet been demonstrated about the effects of the sound of a parametric speaker at the shorter distance between parametric speakers the human body. Therefore, we studied this effect on physiological functions and task performance. Nine male subjects participated in this study. They completed three consecutive sessions: a 20-minute quiet period as a baseline, a 30-minute mental task period with general speakers or parametric speakers, and a 20-minute recovery period. We measured electrocardiogram (ECG photoplethysmogram (PTG, electroencephalogram (EEG, systolic and diastolic blood pressure. Four experiments, one with a speaker condition (general speaker and parametric speaker, the other with a distance condition (0.3 m and 1.0 m, were conducted respectively at the same time of day on separate days. To examine the effects of the speaker and distance, three-way repeated measures ANOVA (speaker factor x distance factor x time factor were conducted. In conclusion, we found that the physiological responses were not significantly different between the speaker condition and the distance condition. Meanwhile, it was shown that the physiological burdens increased with progress in time independently of speaker condition and distance condition. In summary, the effects of the parametric speaker at the 2.6 m distance were not obtained at the distance of 1 m or less.

Rayleigh-type parametric chemical oscillation

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Shyamolina; Ray, Deb Shankar, E-mail: pcdsr@iacs.res.in [Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

2015-09-28

We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.

Rayleigh-type parametric chemical oscillation.

Science.gov (United States)

Ghosh, Shyamolina; Ray, Deb Shankar

2015-09-28

We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.

Generation and application of 15 to 30 MeV parametric X-ray by linac

CERN Document Server

Akimoto, T

2002-01-01

15 to 30 MeV parametric X-ray (PXR) was generated using Si single crystal by 45 MeV electron LINAC. To obtain good monochromatic hard X-ray field, the appropriate conditions were determined by theoretical analysis and experiments. The intensity of PXR was increased with increasing electron energy and crystal rotation angle. However, PXR energy is independent of electron energy. By increasing measurement angle, energy of PXR decreased, but its intensity increased. 15 to 30 keV PXR energy and about 10 sup - sup 5 to 10 sup - sup 6 photon/electron of intensity were observed at 15 to 22 deg detection angle under the operation conditions of 45 MeV electron energy and 4 to 8 nA of beam current. The mass attenuation coefficient of photon of Zr, Nb and Mo, in K absorption edge was measured. Application to determine lattice distortion of target sample and off-angle of crystal was investigated. Generation and detection of PXR, measurement of characteristic properties: crystal rotation angle, detection angle, electron e...

On the unlimited gain of a nonlinear parametric amplifier

DEFF Research Database (Denmark)

Sorokin, Vladislav

2014-01-01

The present paper is concerned with analysis of the response of a nonlinear parametric amplifier in abroad range of system parameters, particularly beyond resonance. Such analysis is of particular interestfor micro- and nanosystems, since many small-scale parametric amplifiers exhibit a distinctly...... nonlinearbehavior when amplitude of their response is sufficiently large. The modified method of direct separa-tion of motions is employed to study the considered system. As the result it is obtained that steady-stateamplitude of the nonlinear parametric amplifier response can reach large values in the case...... of arbitrarilysmall amplitude of external excitation, so that the amplifier gain tends to infinity. Very large amplifiergain can be achieved in a broad range of system parameters, in particular when the amplitude of para-metric excitation is comparatively small. The obtained results clearly demonstrate that very...

Parametric instabilities in magnetized bi-ion and dusty plasmas

Indian Academy of Sciences (India)

-ion or dusty plasma with parametric pumping of the magnetic field is analysed. The equation of motion governing the perturbed plasma is derived and parametrically excited transverse modes propagating along the magnetic field are found.

A capacitive ultrasonic transducer based on parametric resonance.

Science.gov (United States)

Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F

2017-07-24

A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of f o . When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2f o with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at f o frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.

Identification of parametric models with a priori knowledge of process properties

Directory of Open Access Journals (Sweden)

Janiszowski Krzysztof B.

2016-12-01

Full Text Available An approach to estimation of a parametric discrete-time model of a process in the case of some a priori knowledge of the investigated process properties is presented. The knowledge of plant properties is introduced in the form of linear bounds, which can be determined for the coefficient vector of the parametric model studied. The approach yields special biased estimation of model coefficients that preserves demanded properties. A formula for estimation of the model coefficients is derived and combined with a recursive scheme determined for minimization of the sum of absolute model errors. The estimation problem of a model with known static gains of inputs is discussed and proper formulas are derived. This approach can overcome the non-identifiability problem which has been observed during estimation based on measurements recorded in industrial closed-loop control systems. The application of the proposed approach to estimation of a model for an industrial plant (a water injector into the steam flow in a power plant is presented and discussed.

On Parametrization of the Linear GL(4,C) and Unitary SU(4) Groups in Terms of Dirac Matrices

Science.gov (United States)

Red'Kov, Victor M.; Bogush, Andrei A.; Tokarevskaya, Natalia G.

2008-02-01

Parametrization of 4 × 4-matrices G of the complex linear group GL(4,C) in terms of four complex 4-vector parameters (k,m,n,l) is investigated. Additional restrictions separating some subgroups of GL(4,C) are given explicitly. In the given parametrization, the problem of inverting any 4 × 4 matrix G is solved. Expression for determinant of any matrix G is found: det G = F(k,m,n,l). Unitarity conditions G+ = G-1 have been formulated in the form of non-linear cubic algebraic equations including complex conjugation. Several simplest solutions of these unitarity equations have been found: three 2-parametric subgroups G1, G2, G3 - each of subgroups consists of two commuting Abelian unitary groups; 4-parametric unitary subgroup consis! ting of a product of a 3-parametric group isomorphic SU(2) and 1-parametric Abelian group. The Dirac basis of generators Λk, being of Gell-Mann type, substantially differs from the basis λi used in the literature on SU(4) group, formulas relating them are found - they permit to separate SU(3) subgroup in SU(4). Special way to list 15 Dirac generators of GL(4,C) can be used {Λk} = {μiÅνjÅ(μiVνj = KÅL ÅM )}, which permit to factorize SU(4) transformations according to S = eiaμ eibνeikKeilLeimM, where two first factors commute with each other and are isomorphic to SU(2) group, the three last ones are 3-parametric groups, each of them consisting of three Abelian commuting unitary subgroups. Besides, the structure of fifteen Dirac matrices Λk permits to separate twenty 3-parametric subgroups in SU(4) isomorphic to SU(2); those subgroups might be used as bigger elementary blocks in constructing of a general transformation SU(4). It is shown how one can specify the present approach for the pseudounitary group SU(2,2) and SU(3,1).

A parametric reconstruction of the deceleration parameter

Energy Technology Data Exchange (ETDEWEB)

Al Mamon, Abdulla [Manipal University, Manipal Centre for Natural Sciences, Manipal (India); Visva-Bharati, Department of Physics, Santiniketan (India); Das, Sudipta [Visva-Bharati, Department of Physics, Santiniketan (India)

2017-07-15

The present work is based on a parametric reconstruction of the deceleration parameter q(z) in a model for the spatially flat FRW universe filled with dark energy and non-relativistic matter. In cosmology, the parametric reconstruction technique deals with an attempt to build up a model by choosing some specific evolution scenario for a cosmological parameter and then estimate the values of the parameters with the help of different observational datasets. In this paper, we have proposed a logarithmic parametrization of q(z) to probe the evolution history of the universe. Using the type Ia supernova, baryon acoustic oscillation and the cosmic microwave background datasets, the constraints on the arbitrary model parameters q{sub 0} and q{sub 1} are obtained (within 1σ and 2σ confidence limits) by χ{sup 2}-minimization technique. We have then reconstructed the deceleration parameter, the total EoS parameter ω{sub tot}, the jerk parameter and have compared the reconstructed results of q(z) with other well-known parametrizations of q(z). We have also shown that two model selection criteria (namely, the Akaike information criterion and Bayesian information criterion) provide a clear indication that our reconstructed model is well consistent with other popular models. (orig.)

On the Feasibility of Stabilizing Parametric Roll with Active Bifurcation Control

DEFF Research Database (Denmark)

Galeazzi, Roberto; Blanke, Mogens

2007-01-01

When parametric resonance occurs on a ship, large roll motion develops rapidly and severe damage on cargo is likely. Some vessels have even capsized in moderate seas for reasons believed to be parametric resonance. This paper revisits the analysis of parametric resonance and assess the possibility...

Parametric cost models for space telescopes

Science.gov (United States)

Stahl, H. Philip; Henrichs, Todd; Dollinger, Courtnay

2017-11-01

Multivariable parametric cost models for space telescopes provide several benefits to designers and space system project managers. They identify major architectural cost drivers and allow high-level design trades. They enable cost-benefit analysis for technology development investment. And, they provide a basis for estimating total project cost. A survey of historical models found that there is no definitive space telescope cost model. In fact, published models vary greatly [1]. Thus, there is a need for parametric space telescopes cost models. An effort is underway to develop single variable [2] and multi-variable [3] parametric space telescope cost models based on the latest available data and applying rigorous analytical techniques. Specific cost estimating relationships (CERs) have been developed which show that aperture diameter is the primary cost driver for large space telescopes; technology development as a function of time reduces cost at the rate of 50% per 17 years; it costs less per square meter of collecting aperture to build a large telescope than a small telescope; and increasing mass reduces cost.

Parametric Cost Models for Space Telescopes

Science.gov (United States)

Stahl, H. Philip; Henrichs, Todd; Dollinger, Courtney

2010-01-01

Multivariable parametric cost models for space telescopes provide several benefits to designers and space system project managers. They identify major architectural cost drivers and allow high-level design trades. They enable cost-benefit analysis for technology development investment. And, they provide a basis for estimating total project cost. A survey of historical models found that there is no definitive space telescope cost model. In fact, published models vary greatly [1]. Thus, there is a need for parametric space telescopes cost models. An effort is underway to develop single variable [2] and multi-variable [3] parametric space telescope cost models based on the latest available data and applying rigorous analytical techniques. Specific cost estimating relationships (CERs) have been developed which show that aperture diameter is the primary cost driver for large space telescopes; technology development as a function of time reduces cost at the rate of 50% per 17 years; it costs less per square meter of collecting aperture to build a large telescope than a small telescope; and increasing mass reduces cost.

PISC II: Parametric studies. Monitoring of PISC-II parametric studies in ultrasonic NDT for PWR

International Nuclear Information System (INIS)

Toft, M.W.

1989-09-01

The CEGB NDT Applications Centre is partipating in the EEC-funded international Programme for the Inspection of Steel Components (PISC) on account of its relevance to the inspection of Sizewell B and future PWRs. This report describes an inspection monitoring exercise undertaken by NDTAC under partial funding from JRC Ispra, at the initiation of the PISC-III Ultrasonic Modelling Group. Experimental studies have been carried out under PISC-II to investigate ultrasonic defect response as a function of various parameters which characterise the inspection situation. Some of these parametric studies are potentially useful for the validation of theoretical models of ultrasonic inspection and are consequently relevant to the work of the PISC-III Modelling Group. The aim of the present exercise was to ensure that data obtained by the various contract organizations participating in the PISC-II Parametric Studies was of high quality, was a complete record of the inspection and would yield valid comparisons with the predictions of theoretical models. The exercise entailed visits by a nominated CEGB observer to 4 European NDT Laboratories at which the parametric studies were in progress; CISE (Milan); UKAEA (Harwell); UKAEA (Risley) and Vincotte (Brussels). This report presents the findings of those visits

Machine learning-based dual-energy CT parametric mapping.

Science.gov (United States)

Su, Kuan-Hao; Kuo, Jung-Wen; Jordan, David W; Van Hedent, Steven; Klahr, Paul; Wei, Zhouping; Al Helo, Rose; Liang, Fan; Qian, Pengjiang; Pereira, Gisele C; Rassouli, Negin; Gilkeson, Robert C; Traughber, Bryan J; Cheng, Chee-Wai; Muzic, Raymond F

2018-05-22

The aim is to develop and evaluate machine learning methods for generating quantitative parametric maps of effective atomic number (Z_eff), relative electron density (ρ_e), mean excitation energy (I_x), and relative stopping power (RSP) from clinical dual-energy CT data. The maps could be used for material identification and radiation dose calculation. Machine learning methods of historical centroid (HC), random forest (RF), and artificial neural networks (ANN) were used to learn the relationship between dual-energy CT input data and ideal output parametric maps calculated for phantoms from the known compositions of 13 tissue substitutes. After training and model selection steps, the machine learning predictors were used to generate parametric maps from independent phantom and patient input data. Precision and accuracy were evaluated using the ideal maps. This process was repeated for a range of exposure doses, and performance was compared to that of the clinically-used dual-energy, physics-based method which served as the reference. The machine learning methods generated more accurate and precise parametric maps than those obtained using the reference method. Their performance advantage was particularly evident when using data from the lowest exposure, one-fifth of a typical clinical abdomen CT acquisition. The RF method achieved the greatest accuracy. In comparison, the ANN method was only 1% less accurate but had much better computational efficiency than RF, being able to produce parametric maps in 15 seconds. Machine learning methods outperformed the reference method in terms of accuracy and noise tolerance when generating parametric maps, encouraging further exploration of the techniques. Among the methods we evaluated, ANN is the most suitable for clinical use due to its combination of accuracy, excellent low-noise performance, and computational efficiency. . © 2018 Institute of Physics and Engineering in

The impact of parametrized convection on cloud feedback

Science.gov (United States)

Webb, Mark J.; Lock, Adrian P.; Bretherton, Christopher S.; Bony, Sandrine; Cole, Jason N. S.; Idelkadi, Abderrahmane; Kang, Sarah M.; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C.; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D.; Zhao, Ming

2015-01-01

We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that ‘ConvOff’ models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud

Parametric Portfolio Selection: Evaluating and Comparing to Markowitz Portfolios

Directory of Open Access Journals (Sweden)

Marcelo C. Medeiros

2014-10-01

Full Text Available In this paper we exploit the parametric portfolio optimization in the Brazilian market. Our data consists of monthly returns of 306 Brazilian stocks in the period between 2001 and 2013. We tested the model both in and out of sample and compared the results with the value and equal weighted portfolios and with a Markowitz based portfolio. We performed statistical inference in the parametric optimization using bootstrap techniques in order to build the parameters empirical distributions. Our results showed that the parametric optimization is a very efficient technique out of sample. It consistently showed superior results when compared with the VW, EW and Markowitz portfolios even when transaction costs were included. Finally, we consider the parametric approach to be very flexible to the inclusion of constraints in weights, transaction costs and listing and delisting of stocks.

Digital spectral analysis parametric, non-parametric and advanced methods

CERN Document Server

Castanié, Francis

2013-01-01

Digital Spectral Analysis provides a single source that offers complete coverage of the spectral analysis domain. This self-contained work includes details on advanced topics that are usually presented in scattered sources throughout the literature.The theoretical principles necessary for the understanding of spectral analysis are discussed in the first four chapters: fundamentals, digital signal processing, estimation in spectral analysis, and time-series models.An entire chapter is devoted to the non-parametric methods most widely used in industry.High resolution methods a

A general three-dimensional parametric geometry of the native aortic valve and root for biomechanical modeling.

Science.gov (United States)

Haj-Ali, Rami; Marom, Gil; Ben Zekry, Sagit; Rosenfeld, Moshe; Raanani, Ehud

2012-09-21

The complex three-dimensional (3D) geometry of the native tricuspid aortic valve (AV) is represented by select parametric curves allowing for a general construction and representation of the 3D-AV structure including the cusps, commissures and sinuses. The proposed general mathematical description is performed by using three independent parametric curves, two for the cusp and one for the sinuses. These curves are used to generate different surfaces that form the structure of the AV. Additional dependent curves are also generated and utilized in this process, such as the joint curve between the cusps and the sinuses. The model's feasibility to generate patient-specific parametric geometry is examined against 3D-transesophageal echocardiogram (3D-TEE) measurements from a non-pathological AV. Computational finite-element (FE) mesh can then be easily constructed from these surfaces. Examples are given for constructing several 3D-AV geometries by estimating the needed parameters from echocardiographic measurements. The average distance (error) between the calculated geometry and the 3D-TEE measurements was only 0.78±0.63mm. The proposed general 3D parametric method is very effective in quantitatively representing a wide range of native AV structures, with and without pathology. It can also facilitate a methodical quantitative investigation over the effect of pathology and mechanical loading on these major AV parameters. Copyright © 2012 Elsevier Ltd. All rights reserved.

Parametric instabilities of rotor-support systems with application to industrial ventilators

Science.gov (United States)

Parszewski, Z.; Krodkiemski, T.; Marynowski, K.

1980-01-01

Rotor support systems interaction with parametric excitation is considered for both unequal principal shaft stiffness (generators) and offset disc rotors (ventilators). Instability regions and types of instability are computed in the first case, and parametric resonances in the second case. Computed and experimental results are compared for laboratory machine models. A field case study of parametric vibrations in industrial ventilators is reported. Computed parametric resonances are confirmed in field measurements, and some industrial failures are explained. Also the dynamic influence and gyroscopic effect of supporting structures are shown and computed.

Noise-enhanced Parametric Resonance in Perturbed Galaxies

Science.gov (United States)

Sideris, Ioannis V.; Kandrup, Henry E.

2004-02-01

This paper describes how parametric resonances associated with a galactic potential subjected to relatively low-amplitude, strictly periodic time-dependent perturbations can be impacted by pseudo-random variations in the pulsation frequency, modeled as colored noise. One aim thereby is to allow for the effects of a changing oscillation frequency as the density distribution associated with a galaxy evolves during violent relaxation. Another is to mimic the possible effects of internal substructures, satellite galaxies, and/or a high-density environment. The principal conclusions are that allowing for a variable frequency does not vitiate the effects of parametric resonance, and that, in at least some cases, such variations can increase the overall importance of parametric resonance associated with systematic pulsations. In memory of Professor H. E. Kandrup, a brilliant scientist, excellent teacher, and good friend. His genius and sense of humor will be greatly missed.

Application of parametric equations of motion to study the laser induced multiphoton dissociation of H2+ in intense laser field.

Science.gov (United States)

Kalita, Dhruba J; Rao, Akshay; Rajvanshi, Ishir; Gupta, Ashish K

2011-06-14

We have applied parametric equations of motion (PEM) to study photodissociation dynamics of H(2)(+). The resonances are extracted using smooth exterior scaling method. This is the first application of PEM to non-Hermitian Hamiltonian that includes resonances and the continuum. Here, we have studied how the different resonance states behave with respect to the change in field amplitude. The advantage of this method is that one can easily trace the different states that are changing as the field parameter changes.

Acceleration of the direct reconstruction of linear parametric images using nested algorithms

International Nuclear Information System (INIS)

Wang Guobao; Qi Jinyi

2010-01-01

Parametric imaging using dynamic positron emission tomography (PET) provides important information for biological research and clinical diagnosis. Indirect and direct methods have been developed for reconstructing linear parametric images from dynamic PET data. Indirect methods are relatively simple and easy to implement because the image reconstruction and kinetic modeling are performed in two separate steps. Direct methods estimate parametric images directly from raw PET data and are statistically more efficient. However, the convergence rate of direct algorithms can be slow due to the coupling between the reconstruction and kinetic modeling. Here we present two fast gradient-type algorithms for direct reconstruction of linear parametric images. The new algorithms decouple the reconstruction and linear parametric modeling at each iteration by employing the principle of optimization transfer. Convergence speed is accelerated by running more sub-iterations of linear parametric estimation because the computation cost of the linear parametric modeling is much less than that of the image reconstruction. Computer simulation studies demonstrated that the new algorithms converge much faster than the traditional expectation maximization (EM) and the preconditioned conjugate gradient algorithms for dynamic PET.

Chiral analysis of baryon form factors

Energy Technology Data Exchange (ETDEWEB)

Gail, T.A.

2007-11-08

This work presents an extensive theoretical investigation of the structure of the nucleon within the standard model of elementary particle physics. In particular, the long range contributions to a number of various form factors parametrizing the interactions of the nucleon with an electromagnetic probe are calculated. The theoretical framework for those calculations is chiral perturbation theory, the exact low energy limit of Quantum Chromo Dynamics, which describes such long range contributions in terms of a pion-cloud. In this theory, a nonrelativistic leading one loop order calculation of the form factors parametrizing the vector transition of a nucleon to its lowest lying resonance, the {delta}, a covariant calculation of the isovector and isoscalar vector form factors of the nucleon at next to leading one loop order and a covariant calculation of the isoscalar and isovector generalized vector form factors of the nucleon at leading one loop order are performed. In order to perform consistent loop calculations in the covariant formulation of chiral perturbation theory an appropriate renormalization scheme is defined in this work. All theoretical predictions are compared to phenomenology and results from lattice QCD simulations. These comparisons allow for a determination of the low energy constants of the theory. Furthermore, the possibility of chiral extrapolation, i.e. the extrapolation of lattice data from simulations at large pion masses down to the small physical pion mass is studied in detail. Statistical as well as systematic uncertainties are estimated for all results throughout this work. (orig.)

Study on Semi-Parametric Statistical Model of Safety Monitoring of Cracks in Concrete Dams

Directory of Open Access Journals (Sweden)

Chongshi Gu

2013-01-01

Full Text Available Cracks are one of the hidden dangers in concrete dams. The study on safety monitoring models of concrete dam cracks has always been difficult. Using the parametric statistical model of safety monitoring of cracks in concrete dams, with the help of the semi-parametric statistical theory, and considering the abnormal behaviors of these cracks, the semi-parametric statistical model of safety monitoring of concrete dam cracks is established to overcome the limitation of the parametric model in expressing the objective model. Previous projects show that the semi-parametric statistical model has a stronger fitting effect and has a better explanation for cracks in concrete dams than the parametric statistical model. However, when used for forecast, the forecast capability of the semi-parametric statistical model is equivalent to that of the parametric statistical model. The modeling of the semi-parametric statistical model is simple, has a reasonable principle, and has a strong practicality, with a good application prospect in the actual project.

Parametric number covariance in quantum chaotic spectra.

Science.gov (United States)

Vinayak; Kumar, Sandeep; Pandey, Akhilesh

2016-03-01

We study spectral parametric correlations in quantum chaotic systems and introduce the number covariance as a measure of such correlations. We derive analytic results for the classical random matrix ensembles using the binary correlation method and obtain compact expressions for the covariance. We illustrate the universality of this measure by presenting the spectral analysis of the quantum kicked rotors for the time-reversal invariant and time-reversal noninvariant cases. A local version of the parametric number variance introduced earlier is also investigated.

Optical parametric amplification and oscillation assisted by low-frequency stimulated emission.

Science.gov (United States)

Longhi, Stefano

2016-04-15

Optical parametric amplification and oscillation provide powerful tools for coherent light generation in spectral regions inaccessible to lasers. Parametric gain is based on a frequency down-conversion process and, thus, it cannot be realized for signal waves at a frequency ω3 higher than the frequency of the pump wave ω1. In this Letter, we suggest a route toward the realization of upconversion optical parametric amplification and oscillation, i.e., amplification of the signal wave by a coherent pump wave of lower frequency, assisted by stimulated emission of the auxiliary idler wave. When the signal field is resonated in an optical cavity, parametric oscillation is obtained. Design parameters for the observation of upconversion optical parametric oscillation at λ3=465 nm are given for a periodically poled lithium-niobate (PPLN) crystal doped with Nd(3+) ions.

Casas-Ibarra parametrization and leptogenesis

International Nuclear Information System (INIS)

Xing Zhizhong

2010-01-01

The Casas-Ibarra parametrization is a description of the Dirac neutrino mass matrix M D in terms of the neutrino mixing matrix V, an orthogonal matrix O and the diagonal mass matrices of light and heavy Majorana neutrinos in the type-I seesaw mechanism. Because M D + M D is apparently independent of V but dependent on O in this parametrization, a number of authors have claimed that unflavored leptogenesis has nothing to do with CP violation at low energies. Here we question this logic by clarifying the physical meaning of O. We establish a clear relationship between O and the observable quantities, and find that O does depend on V. We show that both unflavored leptogenesis and flavored leptogenesis have no direct connection with low-energy CP violation. (authors)

Worst-case Throughput Analysis for Parametric Rate and Parametric Actor Execution Time Scenario-Aware Dataflow Graphs

Directory of Open Access Journals (Sweden)

Mladen Skelin

2014-03-01

Full Text Available Scenario-aware dataflow (SADF is a prominent tool for modeling and analysis of dynamic embedded dataflow applications. In SADF the application is represented as a finite collection of synchronous dataflow (SDF graphs, each of which represents one possible application behaviour or scenario. A finite state machine (FSM specifies the possible orders of scenario occurrences. The SADF model renders the tightest possible performance guarantees, but is limited by its finiteness. This means that from a practical point of view, it can only handle dynamic dataflow applications that are characterized by a reasonably sized set of possible behaviours or scenarios. In this paper we remove this limitation for a class of SADF graphs by means of SADF model parametrization in terms of graph port rates and actor execution times. First, we formally define the semantics of the model relevant for throughput analysis based on (max,+ linear system theory and (max,+ automata. Second, by generalizing some of the existing results, we give the algorithms for worst-case throughput analysis of parametric rate and parametric actor execution time acyclic SADF graphs with a fully connected, possibly infinite state transition system. Third, we demonstrate our approach on a few realistic applications from digital signal processing (DSP domain mapped onto an embedded multi-processor architecture.

The geometry of distributional preferences and a non-parametric identification approach: The Equality Equivalence Test.

Science.gov (United States)

Kerschbamer, Rudolf

2015-05-01

This paper proposes a geometric delineation of distributional preference types and a non-parametric approach for their identification in a two-person context. It starts with a small set of assumptions on preferences and shows that this set (i) naturally results in a taxonomy of distributional archetypes that nests all empirically relevant types considered in previous work; and (ii) gives rise to a clean experimental identification procedure - the Equality Equivalence Test - that discriminates between archetypes according to core features of preferences rather than properties of specific modeling variants. As a by-product the test yields a two-dimensional index of preference intensity.

Parametric amplification and bidirectional invisibility in PT -symmetric time-Floquet systems

Science.gov (United States)

Koutserimpas, Theodoros T.; Alù, Andrea; Fleury, Romain

2018-01-01

Parity-time (PT )-symmetric wave devices, which exploit balanced interactions between material gain and loss, exhibit extraordinary properties, including lasing and flux-conserving scattering processes. In a seemingly different research field, periodically driven systems, also known as time-Floquet systems, have been widely studied as a relevant platform for reconfigurable active wave control and manipulation. In this article, we explore the connection between PT -symmetry and parametric time-Floquet systems. Instead of relying on material gain, we use parametric amplification by considering a time-periodic modulation of the refractive index at a frequency equal to twice the incident signal frequency. We show that the scattering from a simple parametric slab, whose dynamics follows the Mathieu equation, can be described by a PT -symmetric scattering matrix, whose PT -breaking threshold corresponds to the Mathieu instability threshold. By combining different parametric slabs modulated out of phase, we create PT -symmetric time-Floquet systems that feature exceptional scattering properties, such as coherent perfect absorption (CPA)-laser operation and bidirectional invisibility. These bidirectional properties, rare for regular PT -symmetric systems, are related to a compensation of parametric amplification due to multiple scattering between two parametric systems modulated with a phase difference.

Parametric Modelling of As-Built Beam Framed Structure in Bim Environment

Science.gov (United States)

Yang, X.; Koehl, M.; Grussenmeyer, P.

2017-02-01

A complete documentation and conservation of a historic timber roof requires the integration of geometry modelling, attributional and dynamic information management and results of structural analysis. Recently developed as-built Building Information Modelling (BIM) technique has the potential to provide a uniform platform, which provides possibility to integrate the traditional geometry modelling, parametric elements management and structural analysis together. The main objective of the project presented in this paper is to develop a parametric modelling tool for a timber roof structure whose elements are leaning and crossing beam frame. Since Autodesk Revit, as the typical BIM software, provides the platform for parametric modelling and information management, an API plugin, able to automatically create the parametric beam elements and link them together with strict relationship, was developed. The plugin under development is introduced in the paper, which can obtain the parametric beam model via Autodesk Revit API from total station points and terrestrial laser scanning data. The results show the potential of automatizing the parametric modelling by interactive API development in BIM environment. It also integrates the separate data processing and different platforms into the uniform Revit software.

[Technical background of data collection for parametric observation of total mesorectal excision (TME) in rectal cancer].

Science.gov (United States)

Bláha, M; Hoch, J; Ferko, A; Ryška, A; Hovorková, E

Improvement in any human activity is preconditioned by inspection of results and providing feedback used for modification of the processes applied. Comparison of experts experience in the given field is another indispensable part leading to optimisation and improvement of processes, and optimally to implementation of standards. For the purpose of objective comparison and assessment of the processes, it is always necessary to describe the processes in a parametric way, to obtain representative data, to assess the achieved results, and to provide unquestionable and data-driven feedback based on such analysis. This may lead to a consensus on the definition of standards in the given area of health care. Total mesorectal excision (TME) is a standard procedure of rectal cancer (C20) surgical treatment. However, the quality of performed procedures varies in different health care facilities, which is given, among others, by internal processes and surgeons experience. Assessment of surgical treatment results is therefore of key importance. A pathologist who assesses the resected tissue can provide valuable feedback in this respect. An information system for the parametric assessment of TME performance is described in our article, including technical background in the form of a multicentre clinical registry and the structure of observed parameters. We consider the proposed system of TME parametric assessment as significant for improvement of TME performance, aimed at reducing local recurrences and at improving the overall prognosis of patients. rectal cancer total mesorectal excision parametric data clinical registries TME registry.

Shaping of picosecond pulses for pumping optical parametric amplification

International Nuclear Information System (INIS)

Fueloep, J.A.; Krausz, F.; Major, Zs.; Horvath, B.

2006-01-01

Complete test of publication follows. The use of temporally shaped pump pulses for optical parametric amplification (OPA) is expected to facilitate an increase of efficiency and suppression of possible spectral distortions in this process, since the gain sensitively depends on the pump intensity. Our simulations confirmed such beneficial effect of temporally shaped pump pulses on the OPA process. With the aim to realize an optimized OPA stage pumped by shaped pulses, a novel method for passively shaping narrow band picosecond pulses has been developed. The method is based on the pulse-stacking principle, where replicas of the incoming pulse are created in a specially designed four-beam interferometer. The replicas are recombined with appropriate delays. The interferometer design allows for a unique flexibility in varying the pulse shape, since all relevant degrees of freedom, such as relative intensities and delays between the pulse replicas are independently adjustable. According to our calculations a pulse with a flat-top time profile would provide optimal conditions in the OPA process. Usually the pump pulse needs to be amplified in a conventional laser amplifier prior to the OPA. Our cross-correlation measurements showed that we are able to obtain shaped amplified pulses by shaping the amplifier input. Furthermore, by precompensating the distortions introduced by the amplifier we demonstrated our capability to produce amplified pulses with a flat-top time profile.

Whole vertebral bone segmentation method with a statistical intensity-shape model based approach

Science.gov (United States)

Hanaoka, Shouhei; Fritscher, Karl; Schuler, Benedikt; Masutani, Yoshitaka; Hayashi, Naoto; Ohtomo, Kuni; Schubert, Rainer

2011-03-01

An automatic segmentation algorithm for the vertebrae in human body CT images is presented. Especially we focused on constructing and utilizing 4 different statistical intensity-shape combined models for the cervical, upper / lower thoracic and lumbar vertebrae, respectively. For this purpose, two previously reported methods were combined: a deformable model-based initial segmentation method and a statistical shape-intensity model-based precise segmentation method. The former is used as a pre-processing to detect the position and orientation of each vertebra, which determines the initial condition for the latter precise segmentation method. The precise segmentation method needs prior knowledge on both the intensities and the shapes of the objects. After PCA analysis of such shape-intensity expressions obtained from training image sets, vertebrae were parametrically modeled as a linear combination of the principal component vectors. The segmentation of each target vertebra was performed as fitting of this parametric model to the target image by maximum a posteriori estimation, combined with the geodesic active contour method. In the experimental result by using 10 cases, the initial segmentation was successful in 6 cases and only partially failed in 4 cases (2 in the cervical area and 2 in the lumbo-sacral). In the precise segmentation, the mean error distances were 2.078, 1.416, 0.777, 0.939 mm for cervical, upper and lower thoracic, lumbar spines, respectively. In conclusion, our automatic segmentation algorithm for the vertebrae in human body CT images showed a fair performance for cervical, thoracic and lumbar vertebrae.

Additivity for parametrized topological Euler characteristic and Reidemeister torsion

OpenAIRE

Badzioch, Bernard; Dorabiala, Wojciech

2005-01-01

Dwyer, Weiss, and Williams have recently defined the notions of parametrized topological Euler characteristic and parametrized topological Reidemeister torsion which are invariants of bundles of compact topological manifolds. We show that these invariants satisfy additivity formulas paralleling the additive properties of the classical Euler characteristic and Reidemeister torsion of finite CW-complexes.

Parametric Statistics of Individual Energy Levels in Random Hamiltonians

OpenAIRE

Smolyarenko, I. E.; Simons, B. D.

2002-01-01

We establish a general framework to explore parametric statistics of individual energy levels in disordered and chaotic quantum systems of unitary symmetry. The method is applied to the calculation of the universal intra-level parametric velocity correlation function and the distribution of level shifts under the influence of an arbitrary external perturbation.

Interactive Dimensioning of Parametric Models

KAUST Repository

Kelly, T.

2015-06-22

We propose a solution for the dimensioning of parametric and procedural models. Dimensioning has long been a staple of technical drawings, and we present the first solution for interactive dimensioning: A dimension line positioning system that adapts to the view direction, given behavioral properties. After proposing a set of design principles for interactive dimensioning, we describe our solution consisting of the following major components. First, we describe how an author can specify the desired interactive behavior of a dimension line. Second, we propose a novel algorithm to place dimension lines at interactive speeds. Third, we introduce multiple extensions, including chained dimension lines, controls for different parameter types (e.g. discrete choices, angles), and the use of dimension lines for interactive editing. Our results show the use of dimension lines in an interactive parametric modeling environment for architectural, botanical, and mechanical models.

INVESTIGATION OF DYNAMIC CHARACTERISTICS OF ELEMENTS OF AUTOMATICS OF A SMART HOUSE IN PARAMETRICAL STRUCTURAL SCHEMES

Directory of Open Access Journals (Sweden)

Petrova Irina Yur’evna

2018-01-01

Full Text Available Subject: automation of calculation of dynamic characteristics of the device being designed in the system of conceptual design of sensor equipment, structurally-parametric models of dynamic processes and algorithms for the automated calculation of the qualitative characteristics of elements of the information-measuring and control systems (IMCS. The stage of conceptual design most fully determines the operational characteristics of technical systems. However, none of the information support systems of this stage provides an opportunity to evaluate the performance characteristics of the element being designed taking into account its dynamic characteristics. Research objectives: increasing the effectiveness of the evaluation of dynamic characteristics of sensitive elements of the information-measuring and control systems of a smart house. Materials and methods: when solving the problems posed, the mathematical apparatus of system modeling was used (in particular, the energy-information method of modeling processes of various physical nature that occur in the sensor equipment; the main provisions of the theory of automatic control, the theory of constructing computer-aided design systems, the theory of operational calculus; basics of conceptual design of elements of the information-measuring and control systems. Results: we compared the known automated systems for conceptual design of sensors, highlighted their advantages and disadvantages and we showed that none of these systems allows us to investigate dynamic characteristics of the element being designed in a simple and understandable for engineer form. The authors proposed using energy-information method of modeling for the synthesis of operation principles of sensors and analysis of their dynamic characteristics. We considered elementary dynamic chains and issues of synthesis of parametrical structural schemes that reflect the dynamics of the process with the use of mathematical apparatus of

Parametric Linear Dynamic Logic

Directory of Open Access Journals (Sweden)

Peter Faymonville

2014-08-01

Full Text Available We introduce Parametric Linear Dynamic Logic (PLDL, which extends Linear Dynamic Logic (LDL by temporal operators equipped with parameters that bound their scope. LDL was proposed as an extension of Linear Temporal Logic (LTL that is able to express all ω-regular specifications while still maintaining many of LTL's desirable properties like an intuitive syntax and a translation into non-deterministic Büchi automata of exponential size. But LDL lacks capabilities to express timing constraints. By adding parameterized operators to LDL, we obtain a logic that is able to express all ω-regular properties and that subsumes parameterized extensions of LTL like Parametric LTL and PROMPT-LTL. Our main technical contribution is a translation of PLDL formulas into non-deterministic Büchi word automata of exponential size via alternating automata. This yields a PSPACE model checking algorithm and a realizability algorithm with doubly-exponential running time. Furthermore, we give tight upper and lower bounds on optimal parameter values for both problems. These results show that PLDL model checking and realizability are not harder than LTL model checking and realizability.

Parametric Cost Estimates for an International Competitive Edge

International Nuclear Information System (INIS)

Murphy, L.T.; Hickey, M.

2006-01-01

This paper summarizes the progress to date by CH2M HILL and the UKAEA in development of a parametric modelling capability for estimating the costs of large nuclear decommissioning projects in the United Kingdom (UK) and Europe. The ability to successfully apply parametric cost estimating techniques will be a key factor to commercial success in the UK and European multi-billion dollar waste management, decommissioning and environmental restoration markets. The most useful parametric models will be those that incorporate individual components representing major elements of work: reactor decommissioning, fuel cycle facility decommissioning, waste management facility decommissioning and environmental restoration. Models must be sufficiently robust to estimate indirect costs and overheads, permit pricing analysis and adjustment, and accommodate the intricacies of international monetary exchange, currency fluctuations and contingency. The development of a parametric cost estimating capability is also a key component in building a forward estimating strategy. The forward estimating strategy will enable the preparation of accurate and cost-effective out-year estimates, even when work scope is poorly defined or as yet indeterminate. Preparation of cost estimates for work outside the organizations current sites, for which detailed measurement is not possible and historical cost data does not exist, will also be facilitated. (authors)

Parametric instability in GEO 600 interferometer

International Nuclear Information System (INIS)

Gurkovsky, A.G.; Vyatchanin, S.P.

2007-01-01

We present analysis of undesirable effect of parametric instability in signal recycled GEO 600 interferometer. The basis for this effect is provided by excitation of additional (Stokes) optical mode, having frequency ω 1 , and mirror elastic mode, having frequency ω m , when the optical energy stored in the main FP cavity mode, having frequency ω 0 , exceeds a certain threshold and detuning Δ=ω 0 -ω 1 -ω m is small. We discuss the potential of observing parametric instability and its precursors in GEO 600 interferometer. This approach provides the best option to get familiar with this phenomenon, to develop experimental methods to depress it and to test the effectiveness of these methods in situ

A PARAMETRIC STUDY OF THE INFLUENCE OF SHORT-TERM ...

African Journals Online (AJOL)

(b). (•). Figure I a) The building embedded in a layered formation; b) The building model with base springs. PARAMETRIC STUDY. 'fhe parametric study carried out in this work aims at investigating the effect of the soil flexibility on the internal force distribution of selected structural systems of buildings that are founded on soil.

Parametric Cost and Schedule Modeling for Early Technology Development

Science.gov (United States)

2018-04-02

Research NoteNational Security Rep rt PARAMETRIC MODELING FOR EARLY TECHNOLOGY DEVELOPMENT COST AND SCHEDULE Chuck...Alexander NSR_11x17_Cover_CostModeling_v8.indd 1 11/20/17 3:15 PM PARAMETRIC COST AND SCHEDULE MODELING FOR EARLY  TECHNOLOGY DEVELOPMENT Chuck...COST AND SCHEDULE MODELING FOR EARLY  TECHNOLOGY DEVELOPMENT iii Contents Figures

Developing Parametric Models for the Assembly of Machine Fixtures for Virtual Multiaxial CNC Machining Centers

Science.gov (United States)

Balaykin, A. V.; Bezsonov, K. A.; Nekhoroshev, M. V.; Shulepov, A. P.

2018-01-01

This paper dwells upon a variance parameterization method. Variance or dimensional parameterization is based on sketching, with various parametric links superimposed on the sketch objects and user-imposed constraints in the form of an equation system that determines the parametric dependencies. This method is fully integrated in a top-down design methodology to enable the creation of multi-variant and flexible fixture assembly models, as all the modeling operations are hierarchically linked in the built tree. In this research the authors consider a parameterization method of machine tooling used for manufacturing parts using multiaxial CNC machining centers in the real manufacturing process. The developed method allows to significantly reduce tooling design time when making changes of a part’s geometric parameters. The method can also reduce time for designing and engineering preproduction, in particular, for development of control programs for CNC equipment and control and measuring machines, automate the release of design and engineering documentation. Variance parameterization helps to optimize construction of parts as well as machine tooling using integrated CAE systems. In the framework of this study, the authors demonstrate a comprehensive approach to parametric modeling of machine tooling in the CAD package used in the real manufacturing process of aircraft engines.

Wind Farm parametrization in the mesoscale model WRF

DEFF Research Database (Denmark)

Volker, Patrick; Badger, Jake; Hahmann, Andrea N.

2012-01-01

, but are parametrized as another sub-grid scale process. In order to appropriately capture the wind farm wake recovery and its direction, two properties are important, among others, the total energy extracted by the wind farm and its velocity deficit distribution. In the considered parametrization the individual...... the extracted force is proportional to the turbine area interfacing a grid cell. The sub-grid scale wake expansion is achieved by adding turbulence kinetic energy (proportional to the extracted power) to the flow. The validity of both wind farm parametrizations has been verified against observational data. We...... turbines produce a thrust dependent on the background velocity. For the sub-grid scale velocity deficit, the entrainment from the free atmospheric flow into the wake region, which is responsible for the expansion, is taken into account. Furthermore, since the model horizontal distance is several times...

Ultrashort pulse shaping by optical parametric chirped amplification

International Nuclear Information System (INIS)

Nelet, Ambre

2007-01-01

The aim of this work is to propose new laser architectures based on optical parametric chirped pulse amplification (OPCPA). Common goals of OPCPA pre-amplifiers are to reach high energy level while maintaining the spectrum width and to adapt geometry of the amplified beam to the high power laser chain optics. We consider OPCPA as a way to control and to sculpt ultrashort pulses. Our first set-up aims at thwarting possible time recovery default between pump and signal pulses, which lower the energy extraction. A regenerative OPCPA, idler resonant, is a way to produce a high-intensity and high-repetition rate train of amplified signal replicas. Our second laser system pre-compensates the spectral gain narrowing by sculpting pulses directly within the OPCPA section, where a temporal shaping of the pump beam permits a spectro-spectral shaping of the amplified signal. Finally, we propose an OPCPA based on spatial coding and uniform amplification of spectral signal components by using a fan-out periodically poled crystal and a zero dispersion line. (author) [fr

Quantum theory of novel parametric devices

International Nuclear Information System (INIS)

Drummond, P.D.; Reid, M.D.; Dechoum, K.; Chaturvedi, S.; Olsen, M.; Kheruntsyan, K.; Bradley, A.

2005-01-01

While the parametric amplifier is a widely used and important source of entangled and squeezed photons, there are many possible ways to investigate the physics of intracavity parametric devices. Novel quantum theory of parametric devices in this talk will cover several new types of unconventional devices, including the following topics:- Critical intracavity paramp - We calculate intrinsic limits to entanglement of a quantum paramp, caused by nonlinear effects originating in phase noise of the pump. - Degenerate planar paramp - We obtain universal quantum critical fluctuations in a planar paramp device by mapping to the equations of magnetic Lifshitz points Nondegenerate planar paramp - The Mermin-Wagner theorem is used to demonstrate that there is no phase transition in the case of a nondegenerate planar device - Coupled channel paramp - A robust and novel integrated entanglement source can be generated using type I waveguides coupled inside a cavity to generate spatial entanglement - Cascade paramps - This possible 'GHZ-type' source is obtained by cascading successive down conversion crystals inside the same cavity, giving two thresholds Parallel paramps - Tripartite entanglement can be generated if three intracavity paramp crystals are operated in parallel, each idler mode acting as a signal for the next. Finally, we briefly treat the relevant experimental developments. (author)

Observations of MeV electrons and scattered light from intense, subpicosecond laser-plasma interactions

International Nuclear Information System (INIS)

Darrow, C.; Lane, S.; Klem, D.; Perry, M.D.

1993-01-01

In this paper the authors present work in progress in their experimental investigation of the coupling of intense, subpicosecond laser pulses with plasmas preformed on solid targets. (This situation is to be contrasted with the interaction of intense laser fields with solid-density matter. A subject which has generated considerable interest in the last several years.) The characterization of the energy distribution of energetic electrons which escape a solid target irradiated by an intense laser is discussed. The authors have also performed experiments to study the excitation of parametric instabilities near the quarter-critical layer and second-harmonic generation near the critical layer in the plasma. They discuss some preliminary scattered light spectroscopy measurements

Parametric Room Acoustic workflows with real-time acoustic simulation

DEFF Research Database (Denmark)

Parigi, Dario

2017-01-01

The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages......The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages...

Decomposing the variation of aggregate electricity intensity in Spanish industry

International Nuclear Information System (INIS)

Gonzalez, P.F.; Suarez, R.P.

2003-01-01

Several papers have dealt with methodological and application issues related to techniques for decomposing changes in environmental indicators. This paper aims to decompose changes in electricity intensity in Spanish industry and to explain the factors that contribute to these changes. Focusing on an energy intensity approach based on Divisia indices, we began by reviewing the two general parametric Divisia methods and six specific cases. In order to avoid obtaining significantly different results by using differing methods, all of them have been applied to Spanish data. Also two different disaggregation levels have been taken into consideration. Combined with electricity price analysis, the results of this paper indicate the poor contribution of structural change to substantial reductions in aggregate electricity intensity, and underline the role of innovation, development, diffusion and access to more efficient technologies as main contributors to the reduction of the energy/production ratio. (author)

Use of statistical parametric mapping of 18F-FDG-PET in frontal lobe epilepsy

International Nuclear Information System (INIS)

Plotkin, M.; Amthauer, H.; Luedemann, L.; Hartkop, E.; Ruf, J.; Gutberlet, M.; Bertram, H.; Felix, R.; Venz, St.; Merschhemke, M.; Meencke, H.-J.

2003-01-01

Aim: Evaluation of the use of statistical parametrical mapping (SPM) of FDG-PET for seizure lateralization in frontal lobe epilepsy. Patients: 38 patients with suspected frontal lobe epilepsy supported by clinical findings and video-EEG monitoring. Method: Statistical parametrical maps were generated by subtraction of individual scans from a control group, formed by 16 patients with negative neurological/psychiatric history and no abnormalities in the MR scan. The scans were also analyzed visually as well as semiquantitatively by manually drawn ROIs. Results: SPM showed a better accordance to the results of surface EEG monitoring compared with visual scan analysis and ROI quantification. In comparison with intracranial EEG recordings, the best performance was achieved by combining the ROI based quantification with SPM analysis. Conclusion: These findings suggest that SPM analysis of FDG-PET data could be a useful as complementary tool in the evaluation of seizure focus lateralization in patients with supposed frontal lobe epilepsy. (orig.)

Acoustic Imaging of Selected Areas of Gdansk Bay with the Aid of Parametric Echosounder and Side-Scan Sonar

Directory of Open Access Journals (Sweden)

Grelowska Grażyna

2017-12-01

Full Text Available The article presents and analyses the data recorded during sounding of the Gdansk Bay seabed with the aid of a parametric echosounder and a side-scan sonar. The accuracy of seabed structure examination, as a condition for obtaining valuable results, requires correct configuration of echolocation devices and proper calibration of peripheral devices, such as the survey unit geographical position sensor - GPS, the navigation unit, the MRU-Z sensor of pitch, roll and heave, and the sound velocity meter, which deliver the data to the bathymetric measurement system. Parametric seabed profilers deliver two types of data: the envelope, and the detailed echo signal without processing. The envelope is used for data visualisation in the form of online echograms, while the echo signal is stored for further analyses, to be performed using dedicated software or, after relevant conversion, in arbitrary programming environment1. The presented data analysis is illustrated by selected sample images recorded by the parametric echosounder and the side-scan sonar during Gdansk Bay sounding.

Mathematical algorithm development and parametric studies with the GEOFRAC three-dimensional stochastic model of natural rock fracture systems

Science.gov (United States)

Ivanova, Violeta M.; Sousa, Rita; Murrihy, Brian; Einstein, Herbert H.

2014-06-01

This paper presents results from research conducted at MIT during 2010-2012 on modeling of natural rock fracture systems with the GEOFRAC three-dimensional stochastic model. Following a background summary of discrete fracture network models and a brief introduction of GEOFRAC, the paper provides a thorough description of the newly developed mathematical and computer algorithms for fracture intensity, aperture, and intersection representation, which have been implemented in MATLAB. The new methods optimize, in particular, the representation of fracture intensity in terms of cumulative fracture area per unit volume, P32, via the Poisson-Voronoi Tessellation of planes into polygonal fracture shapes. In addition, fracture apertures now can be represented probabilistically or deterministically whereas the newly implemented intersection algorithms allow for computing discrete pathways of interconnected fractures. In conclusion, results from a statistical parametric study, which was conducted with the enhanced GEOFRAC model and the new MATLAB-based Monte Carlo simulation program FRACSIM, demonstrate how fracture intensity, size, and orientations influence fracture connectivity.

Second-order analysis of inhomogeneous spatial point processes with proportional intensity functions

DEFF Research Database (Denmark)

Guan, Yongtao; Waagepetersen, Rasmus; Beale, Colin M.

2008-01-01

of the intensity functions. The first approach is based on nonparametric kernel-smoothing, whereas the second approach uses a conditional likelihood estimation approach to fit a parametric model for the pair correlation function. A great advantage of the proposed methods is that they do not require the often...... to two spatial point patterns regarding the spatial distributions of birds in the U.K.'s Peak District in 1990 and 2004....

Comparison of parametric and bootstrap method in bioequivalence test.

Science.gov (United States)

Ahn, Byung-Jin; Yim, Dong-Seok

2009-10-01

The estimation of 90% parametric confidence intervals (CIs) of mean AUC and Cmax ratios in bioequivalence (BE) tests are based upon the assumption that formulation effects in log-transformed data are normally distributed. To compare the parametric CIs with those obtained from nonparametric methods we performed repeated estimation of bootstrap-resampled datasets. The AUC and Cmax values from 3 archived datasets were used. BE tests on 1,000 resampled datasets from each archived dataset were performed using SAS (Enterprise Guide Ver.3). Bootstrap nonparametric 90% CIs of formulation effects were then compared with the parametric 90% CIs of the original datasets. The 90% CIs of formulation effects estimated from the 3 archived datasets were slightly different from nonparametric 90% CIs obtained from BE tests on resampled datasets. Histograms and density curves of formulation effects obtained from resampled datasets were similar to those of normal distribution. However, in 2 of 3 resampled log (AUC) datasets, the estimates of formulation effects did not follow the Gaussian distribution. Bias-corrected and accelerated (BCa) CIs, one of the nonparametric CIs of formulation effects, shifted outside the parametric 90% CIs of the archived datasets in these 2 non-normally distributed resampled log (AUC) datasets. Currently, the 80~125% rule based upon the parametric 90% CIs is widely accepted under the assumption of normally distributed formulation effects in log-transformed data. However, nonparametric CIs may be a better choice when data do not follow this assumption.

Prediction of Parametric Roll Resonance by Multilayer Perceptron Neural Network

DEFF Research Database (Denmark)

Míguez González, M; López Peña, F.; Díaz Casás, V.

2011-01-01

Parametric roll resonance is a ship stability related phenomenon that generates sudden large amplitude oscillations up to 30-40 degrees of roll. This can cause severe damage, and it can put the crew in serious danger. The need for a parametric rolling real time prediction system has been acknowle......Parametric roll resonance is a ship stability related phenomenon that generates sudden large amplitude oscillations up to 30-40 degrees of roll. This can cause severe damage, and it can put the crew in serious danger. The need for a parametric rolling real time prediction system has been...... acknowledged in the last few years. This work proposes a prediction system based on a multilayer perceptron (MP) neural network. The training and testing of the MP network is accomplished by feeding it with simulated data of a three degrees-of-freedom nonlinear model of a fishing vessel. The neural network...

Violation of multiparticle Bell inequalities for low- and high-flux parametric amplification using both vacuum and entangled input states

International Nuclear Information System (INIS)

Reid, M.D.; Munro, W.J.; De Martini, F.

2002-01-01

We show how polarization measurements on the output fields generated by parametric down conversion will reveal a violation of multiparticle Bell inequalities, in the regime of both low- and high-output intensity. In this case, each spatially separated system, upon which a measurement is performed, is comprised of more than one particle. In view of the formal analogy with spin systems, the proposal provides an opportunity to test the predictions of quantum mechanics for spatially separated higher spin states. Here the quantum behavior possible even where measurements are performed on systems of large quantum (particle) number may be demonstrated. Our proposal applies to both vacuum-state signal and idler inputs, and also to the quantum-injected parametric amplifier as studied by De Martini et al. The effect of detector inefficiencies is included, and weaker Bell-Clauser-Horne inequalities are derived to enable realistic tests of local hidden variables with auxiliary assumptions for the multiparticle situation

Enhancement and suppression of opto-acoustic parametric interactions using optical feedback

International Nuclear Information System (INIS)

Zhang Zhongyang; Zhao Chunnong; Ju, L.; Blair, D. G.

2010-01-01

A three mode opto-acoustic parametric amplifier (OAPA) is created when two orthogonal optical modes in a high finesse optical cavity are coupled via an acoustic mode of the cavity mirror. Such interactions are predicted to occur in advanced long baseline gravitational wave detectors. They can have high positive gain, which leads to strong parametric instability. Here we show that an optical feedback scheme can enhance or suppress the parametric gain of an OAPA, allowing exploration of three-mode parametric interactions, especially in cavity systems that have insufficient optical power to achieve spontaneous instability. We derive analytical equations and show that optical feedback is capable of controlling predicted instabilities in advanced gravitational wave detectors within a time scale of 13∼10 s.

Analytical Analysis on Nonlinear Parametric Vibration of an Axially Moving String with Fractional Viscoelastic Damping

Directory of Open Access Journals (Sweden)

Ying Li

2017-01-01

Full Text Available The nonlinear parametric vibration of an axially moving string made by rubber-like materials is studied in the paper. The fractional viscoelastic model is used to describe the damping of the string. Then, a new nonlinear fractional mathematical model governing transverse motion of the string is derived based on Newton’s second law, the Euler beam theory, and the Lagrangian strain. Taking into consideration the fractional calculus law of Riemann-Liouville form, the principal parametric resonance is analytically investigated via applying the direct multiscale method. Numerical results are presented to show the influences of the fractional order, the stiffness constant, the viscosity coefficient, and the axial-speed fluctuation amplitude on steady-state responses. It is noticeable that the amplitudes and existing intervals of steady-state responses predicted by Kirchhoff’s fractional material model are much larger than those predicted by Mote’s fractional material model.

Critical sets in one-parametric mathematical programs with complementarity constraints

NARCIS (Netherlands)

Bouza Allende, G.; Guddat, J.; Still, Georg J.

2008-01-01

One-parametric mathematical programs with complementarity constraints are considered. The structure of the set of generalized critical points is analysed for the generic case. It is shown how this analysis can locally be reduced to the study of appropriate standard one-parametric finite problems. By

Parametric Landau damping of space charge modes

Energy Technology Data Exchange (ETDEWEB)

Macridin, Alexandru [Fermilab; Burov, Alexey [Fermilab; Stern, Eric [Fermilab; Amundson, James [Fermilab; Spentzouris, Panagiotis [Fermilab

2016-09-23

Landau damping is the mechanism of plasma and beam stabilization; it arises through energy transfer from collective modes to the incoherent motion of resonant particles. Normally this resonance requires the resonant particle's frequency to match the collective mode frequency. We have identified an important new damping mechanism, parametric Landau damping, which is driven by the modulation of the mode-particle interaction. This opens new possibilities for stability control through manipulation of both particle and mode-particle coupling spectra. We demonstrate the existence of parametric Landau damping in a simulation of transverse coherent modes of bunched accelerator beams with space charge.

Parametric frequency conversion in long Josephson junctions

International Nuclear Information System (INIS)

Irie, F.; Ashihara, S.; Yoshida, K.

1976-01-01

Current steps at voltages corresponding to the parametric coupling between an applied r.f. field and junction resonant modes have been observed in long Josephson tunnel junctions in the flux-flow state. The observed periodic variations of the step height due to the applied magnetic field are explained quantitatively by a perturbational analysis using Josephson phase equations. The present study demonstrates that the moving vortex array can serve as a coherent pump wave for signal waves propagating in the barrier region, which indicates, as a result, the possibility of traveling-wave parametric devices with long Josephson tunnel junctions. (author)

Optical parametric amplification and oscillation assisted by low-frequency stimulated emission

OpenAIRE

Longhi, Stefano

2016-01-01

Optical parametric amplification/oscillation provide a powerful tool for coherent light generation in spectral regions inaccessible to lasers. Parametric gain is based on a frequency {\\it down-conversion} process, and thus it can not be realized for signal waves at a frequency $\\omega_3$ {\\it higher} than the frequency of the pump wave $\\omega_1$. In this work we suggest a route toward the realization of {\\it up-conversion} optical parametric amplification and oscillation, i.e. amplification ...

Comparison of parametric and linear mass detection in the presence of detection noise

International Nuclear Information System (INIS)

Yie, Zi; Zielke, Mark A; Burgner, Christopher B; Turner, Kimberly L

2011-01-01

We experimentally investigate the performance of a nonlinear parametrically driven mass sensor in the presence of detection noise. Mass detection is achieved by measuring the amount of methanol vapor adsorption on the sensor. To demonstrate the advantage of parametric sensing in counteracting the influence of detection noise, we operate the sensor in both the parametric and harmonic resonance mode. Comparison of the results shows that in contrast to conventional linear harmonic sensing, the detection sensitivity does not deteriorate for the parametric case when a tenfold increase in detection noise is introduced. Furthermore, we demonstrate additional functionality of the parametric sensor by utilizing it as a threshold detector, whose performance remains the same despite the added detection noise. Taken together, these results suggest that for mass detection in the presence of detection noise, a parametrically operated sensor may offer better performance over one operated harmonically in the linear regime.

Daylight Adaptive Shading Using Parametric Camshaft Mechanism for SOHO in Jakarta

Directory of Open Access Journals (Sweden)

Sjarifudin Firza Utama

2014-03-01

Full Text Available This research analyzes SOHO (Small Office Home Office which can adjust to the need of visual comfort for the users through natural daylighting and also can be adapted to standard requirements of 14 creative industry workspace in Jakartas. The method of the research is by simulating the SOHO unit with variation of shading opening angles in order to adapt to each unit. Analysis done to every shading opening angle to get the appropriate daylight intensity level which support the work activities in every unit for the whole day. In order for the shading to be able to adapt to the changing daylight condition, previously developed parametric camshaft mechanism was used. The study found that the visual comfort for SOHO with creative industries workers in Jakarta can be achieve by varying the shading opening angles between 15-75°.

Intensity limits for propagation of 0.527 μm laser beams through large-scale-length plasmas for inertial confinement fusion

International Nuclear Information System (INIS)

Niemann, C.; Divol, L.; Froula, D.H.; Gregori, G.; Jones, O.; Kirkwood, R.K.; MacKinnon, A.J.; Meezan, N.B.; Moody, J.D.; Sorce, C.; Suter, L.J.; Glenzer, S.H.; Bahr, R.; Seka, W.

2005-01-01

We have established the intensity limits for propagation of a frequency-doubled (2ω, 527 nm) high intensity interaction beam through an underdense large-scale-length plasma. We observe good beam transmission at laser intensities at or below 2x10 14 W/cm 2 and a strong reduction at intensities up to 10 15 W/cm 2 due to the onset of parametric scattering instabilities. We show that temporal beam smoothing by spectral dispersion allows a factor of 2 higher intensities while keeping the beam spray constant, which establishes frequency-doubled light as an option for ignition and burn in inertial confinement fusion experiments

The parametric resonance—from LEGO Mindstorms to cold atoms

Science.gov (United States)

Kawalec, Tomasz; Sierant, Aleksandra

2017-07-01

We show an experimental setup based on a popular LEGO Mindstorms set, allowing us to both observe and investigate the parametric resonance phenomenon. The presented method is simple but covers a variety of student activities like embedded software development, conducting measurements, data collection and analysis. It may be used during science shows, as part of student projects and to illustrate the parametric resonance in mechanics or even quantum physics, during lectures or classes. The parametrically driven LEGO pendulum gains energy in a spectacular way, increasing its amplitude from 10° to about 100° within a few tens of seconds. We provide also a short description of a wireless absolute orientation sensor that may be used in quantitative analysis of driven or free pendulum movement.

The parametric resonance—from LEGO Mindstorms to cold atoms

International Nuclear Information System (INIS)

Kawalec, Tomasz; Sierant, Aleksandra

2017-01-01

We show an experimental setup based on a popular LEGO Mindstorms set, allowing us to both observe and investigate the parametric resonance phenomenon. The presented method is simple but covers a variety of student activities like embedded software development, conducting measurements, data collection and analysis. It may be used during science shows, as part of student projects and to illustrate the parametric resonance in mechanics or even quantum physics, during lectures or classes. The parametrically driven LEGO pendulum gains energy in a spectacular way, increasing its amplitude from 10° to about 100° within a few tens of seconds. We provide also a short description of a wireless absolute orientation sensor that may be used in quantitative analysis of driven or free pendulum movement. (paper)

Fast, Sequence Adaptive Parcellation of Brain MR Using Parametric Models

DEFF Research Database (Denmark)

Puonti, Oula; Iglesias, Juan Eugenio; Van Leemput, Koen

2013-01-01

In this paper we propose a method for whole brain parcellation using the type of generative parametric models typically used in tissue classification. Compared to the non-parametric, multi-atlas segmentation techniques that have become popular in recent years, our method obtains state-of-the-art ...

Relativistic parametric instabilities in extended extragalactic radio sources

Energy Technology Data Exchange (ETDEWEB)

Ferrari, A [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Trussoni, E; Zaninetti, L

1978-01-01

A general discussion is presented of parametric instabilities of electromagnetic waves in cold plasmas. Previous results for f = eE/msub(e)c..omega../sub 0/ >> 1 and << 1 are extended and the intermediate range f approximately 1, which could be relevant in some astrophysical applications, is analysed by numerical techniques. In the final section a model for particle acceleration and radiation emission by turbulent plasma modes excited in extended radiosources by parametric absorption of strong electromagnetic waves is tentatively discussed.

Bayesian non- and semi-parametric methods and applications

CERN Document Server

Rossi, Peter

2014-01-01

This book reviews and develops Bayesian non-parametric and semi-parametric methods for applications in microeconometrics and quantitative marketing. Most econometric models used in microeconomics and marketing applications involve arbitrary distributional assumptions. As more data becomes available, a natural desire to provide methods that relax these assumptions arises. Peter Rossi advocates a Bayesian approach in which specific distributional assumptions are replaced with more flexible distributions based on mixtures of normals. The Bayesian approach can use either a large but fixed number

Applying Parametric Fault Detection to a Mechanical System

DEFF Research Database (Denmark)

Felício, P.; Stoustrup, Jakob; Niemann, H.

2002-01-01

A way of doing parametric fault detection is described. It is based on the representation of parameter changes as linear fractional transformations (lfts). We describe a model with parametric uncertainty. Then a stabilizing controller is chosen and its robustness properties are studied via mu. Th....... The parameter changes (faults) are estimated based on estimates of the fictitious signals that enter the delta block in the lft. These signal estimators are designed by H-infinity techniques. The chosen example is an inverted pendulum....

On the parametrization of lateral dose profiles in proton radiation therapy

CERN Document Server

Embriaco, A

2015-01-01

Hadrontherapy requires a good knowledge of the physical interactions of the particles when they cross the biological tissue: one of the aspects that determine the characterization of the beam is the study of the lateral profile. We study different parametrizations for the lateral dose profile of protons beam in water considering different energies at different depth. We compare six functions: we start from the well known Gaussian and Double Gaussian parametrizations and also analyse more recent parametrization obtained with Triple Gaussian and Double Gaussian Lorentz-Cauchy functions. Finally we propose alternative parametrizations based on the Gauss-Rutherford and Gauss-Levy functions. The goal is to improve the performances of the actual treatment planning used in proton beam therapy by suggesting alternative approaches to the Gaussian description typically employed.

QCD parametrizations of the parton distribution of deep inelastic scattering

International Nuclear Information System (INIS)

Kotikov, A.V.; Maksimov, S.J.; Parobij, I.S.

1993-01-01

A realistic parametrization of the gluon and quarks distributions is suggested. It is shown that the solutions of the Gribov-Lipatov-Altarelli-Paris equations can be presented by these parametrizations and these equations unambiguously lead to the constraints on the Q 2 -evolution of the parameters. (author). 10 refs

Parametric Equations: Push 'Em Back, Push 'Em Back, Way Back!

Science.gov (United States)

Cieply, Joseph F.

1993-01-01

Stresses using the features of graphing calculators to teach parametric equations much earlier in the curriculum than is presently done. Examples using parametric equations to teach slopes and lines in beginning algebra, inverse functions in advanced algebra, the wrapping function, and simulations of physical phenomena are presented. (MAZ)

Parametric Architecture in the Urban Space

Science.gov (United States)

Januszkiewicz, Krystyna; Kowalski, Karol G.

2017-10-01

The paper deals with the parametric architecture which is trying to introduce a new spatial language in the context for urban tissue that correspond to the artistic consciousness and the attitude of information and digital technologies era. The first part of the paper defines the main features of parametric architecture (such as: folding, continuity and curvilinearity) which are are characteristic of the new style of named the “parametricism”. This architecture is a strong emphasis on geometry, materiality, feasibility and sustainability, what emerges is an explicit agenda promoting material ornamentation, spatial spectacle and formal theatricality. The second part presents result of case study, especially parametric public use buildings, within the tissue of city. The analyzed objects are: The Sage Gateshead (1998-2004) in Gateshead, Kunsthaus in Graz (2000-2003), the Weltstadthaus (2003-2005) in Cologne, The Golden Terraces in Warsaw (2000-2007), the Metropol Parasol in Seville (2005-2011) the King Cross Station (2005-2012) in London, the headquarters of the Pathé Foundation (2006-2014) in Paris. Each of the enumerated examples shows a diverse approach to designing in the urban space, which reflect the age of digital technologies and the information society. In conclusion emphasizes, that new concept of the spatialization of architecture is the equivalent of the democratization of the political system, the liberalization of the economy, among other examples.

The package PAKPDF ver. 1.1 of parametrizations of parton distribution functions in the proton

International Nuclear Information System (INIS)

Charchula, K.

1991-08-01

A FORTRAN package containing parametrizations of parton distribution functions (PDFS) in the proton is described. It allows an easy access to PDFS provided by several recent parametrizations and to some parameters characterizing particular parametrization. Some comments about the use of various parametrizations are also included. (orig.)

Parametric Resonance in a Time-Dependent Harmonic Oscillator

Directory of Open Access Journals (Sweden)

P. N. Nesterov

2013-01-01

Full Text Available In this paper, we study the phenomenon of appearance of new resonances in a timedependent harmonic oscillator under an oscillatory decreasing force. The studied equation belongs to the class of adiabatic oscillators and arises in connection with the spectral problem for the one-dimensional Schr¨odinger equation with Wigner–von Neumann type potential. We use a specially developed method for asymptotic integration of linear systems of differential equations with oscillatory decreasing coefficients. This method uses the ideas of the averaging method to simplify the initial system. Then we apply Levinson’s fundamental theorem to get the asymptotics for its solutions. Finally, we analyze the features of a parametric resonance phenomenon. The resonant frequencies of perturbation are found and the pointwise type of the parametric resonance phenomenon is established. In conclusion, we construct an example of a time-dependent harmonic oscillator (adiabatic oscillator in which the parametric resonances, mentioned in the paper, may occur.

Epicyclic helical channels for parametric resonance ionization cooling

Energy Technology Data Exchange (ETDEWEB)

Johson, Rolland Paul [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Derbenev, Yaroslav [Muons, Inc., Batavia, IL (United States)

2015-08-23

Proposed next-generation muon colliders will require major technical advances to achieve rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam’s angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parameter range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented.

Improved parametric fits for the HeH2 ab initio energy surface

International Nuclear Information System (INIS)

Muchnick, P.

1992-01-01

A brief history of the development of ab initio calculations for the HeH 2 quasi-molecule energy surface, and the parametric fits to these ab initio calculations, is presented. The concept of 'physical reasonableness' of the parametric fit is discussed. Several new improved parametric fits for the energy surface, meeting these requirements, are then proposed. One fit extends the Russek-Garcia parametric fit for the deep repulsion region to include r-dependent parameters, resulting in a more physically reasonable fit with smaller average error. This improved surface fit is applied to quasi-elastic collisions of He on H 2 in the impulse approximation. Previous classical calculations of the scaled inelastic vibrorotational excitation energy distributions are improved with this more accurate parametric fit of the energy surface and with the incorporation of quantum effects in vibrational excitation. It is shown that Sigmund's approach in developing his scaling law is incomplete in the contribution of the three-body interactions to vibrational excitation of the H 2 molecule is concerned. The Sigmund theory is extended to take into account for r-dependency of three-body interactions. A parametric fit for the entire energy surface from essentially 0 ≤R≤∞ and 1.2≤r≤1.6 a.u., where R is the intermolecular spacing and r is the hydrogen bonding length, is also presented. This fit is physically reasonable in all asymptotic limits. This first, full surface parametric fit is based primarily upon a composite of ab initio studies by Russek and Garcia and Meyer, Hariharan and Kutzelnigg. Parametric fits for the H 2 (1sσ g ) 2 , H 2 + (1sσ g ), H 2 + (2pσ u ) and (LiH 2 ) + energy surfaces are also presented. The new parametric fits for H 2 , H 2 + (1sσ g ) are shown to be improvements over the well-known Morse potentials for these surfaces

Reduced clot debris size using standing waves formed via high intensity focused ultrasound

Science.gov (United States)

Guo, Shifang; Du, Xuan; Wang, Xin; Lu, Shukuan; Shi, Aiwei; Xu, Shanshan; Bouakaz, Ayache; Wan, Mingxi

2017-09-01

The feasibility of utilizing high intensity focused ultrasound (HIFU) to induce thrombolysis has been demonstrated previously. However, clinical concerns still remain related to the clot debris produced via fragmentation of the original clot potentially being too large and hence occluding downstream vessels, causing hazardous emboli. This study investigates the use of standing wave fields formed via HIFU to disintegrate the thrombus while achieving a reduced clot debris size in vitro. The results showed that the average diameter of the clot debris calculated by volume percentage was smaller in the standing wave mode than in the travelling wave mode at identical ultrasound thrombolysis settings. Furthermore, the inertial cavitation dose was shown to be lower in the standing wave mode, while the estimated cavitation bubble size distribution was similar in both modes. These results show that a reduction of the clot debris size with standing waves may be attributed to the particle trapping of the acoustic potential well which contributed to particle fragmentation.

Circulation and Directional Amplification in the Josephson Parametric Converter

Science.gov (United States)

Hatridge, Michael

Nonreciprocal transport and directional amplification of weak microwave signals are fundamental ingredients in performing efficient measurements of quantum states of flying microwave light. This challenge has been partly met, as quantum-limited amplification is now regularly achieved with parametrically-driven, Josephson-junction based superconducting circuits. However, these devices are typically non-directional, requiring external circulators to separate incoming and outgoing signals. Recently this limitation has been overcome by several proposals and experimental realizations of both directional amplifiers and circulators based on interference between several parametric processes in a single device. This new class of multi-parametrically driven devices holds the promise of achieving a variety of desirable characteristics simultaneously- directionality, reduced gain-bandwidth constraints and quantum-limited added noise, and are good candidates for on-chip integration with other superconducting circuits such as qubits.

Dispersion-Engineered Traveling Wave Kinetic Inductance Parametric Amplifier

Science.gov (United States)

Zmuidzinas, Jonas (Inventor); Day, Peter K. (Inventor)

2014-01-01

A traveling wave kinetic inductance parametric amplifier comprises a superconducting transmission line and a dispersion control element. The transmission line can include periodic variations of its dimension along its length. The superconducting material can include a high normal state resistivity material. In some instances the high normal state resistivity material includes nitrogen and a metal selected from the group consisting of titanium, niobium and vanadium. The traveling wave kinetic inductance parametric amplifier is expected to exhibit a noise temperature below 100 mK/GHz.

Parametric instability of a large-amplitude nonmonochromatic Alfvacute en wave

International Nuclear Information System (INIS)

Malara, F.; Velli, M.

1996-01-01

The parametric instability of a finite-amplitude Alfvacute en wave is studied in a one-dimensional geometry. The pump wave is an exact solution of the nonlinear magnetohydrodynamic (MHD) equations, i.e., the magnetic field perturbation has a uniform intensity and rotates in the plane perpendicular to the propagation direction, but its Fourier spectrum contains several wavelengths. The weakly nonmonochromatic regime is first studied by an analytical approach. It is shown that the growth rate of the instability decreases quadratically with a parameter that measures the departure from the monochromatic case. The fully nonmonochromatic case is studied by numerically solving the instability equations, when the phase function of the pump wave has a power-law spectrum. Though the growth rate is maximum in the monochromatic case, it remains of the same order of magnitude also for wide spectrum pump waves. For quasimonochromatic waves the correction to the growth rate depends only on the spectral index of the phase function. copyright 1996 American Institute of Physics

Gaussian random-matrix process and universal parametric correlations in complex systems

International Nuclear Information System (INIS)

Attias, H.; Alhassid, Y.

1995-01-01

We introduce the framework of the Gaussian random-matrix process as an extension of Dyson's Gaussian ensembles and use it to discuss the statistical properties of complex quantum systems that depend on an external parameter. We classify the Gaussian processes according to the short-distance diffusive behavior of their energy levels and demonstrate that all parametric correlation functions become universal upon the appropriate scaling of the parameter. The class of differentiable Gaussian processes is identified as the relevant one for most physical systems. We reproduce the known spectral correlators and compute eigenfunction correlators in their universal form. Numerical evidence from both a chaotic model and weakly disordered model confirms our predictions

Excess quantum noise in optical parametric chirped-pulse amplification

OpenAIRE

Manzoni, C.; Moses, J.; Kärtner, F. X.; Cerullo, G.

2011-01-01

Noise evolution in an optical parametric chirped-pulse amplifier (OPCPA) differs essentially from that of an optical parametric or a conventional laser amplifier, in that an incoherent pedestal is produced by superfluorescence that can overwhelm the signal under strong saturation. Using a model for the nonlinear dynamics consistent with quantum mechanics, we numerically study the evolution of excess noise in an OPCPA. The observed dynamics explain the macroscopic characteristics seen previous...

Global optimization of silicon nanowires for efficient parametric processes

DEFF Research Database (Denmark)

Vukovic, Dragana; Xu, Jing; Mørk, Jesper

2013-01-01

We present a global optimization of silicon nanowires for parametric single-pump mixing. For the first time, the effect of surface roughness-induced loss is included in the analysis, significantly influencing the optimum waveguide dimensions.......We present a global optimization of silicon nanowires for parametric single-pump mixing. For the first time, the effect of surface roughness-induced loss is included in the analysis, significantly influencing the optimum waveguide dimensions....

Parametric amplification of metric fluctuations during reheating in two field models

International Nuclear Information System (INIS)

Finelli, F.; Brandenberger, R.

2000-01-01

We study the parametric amplification of super-Hubble-scale scalar metric fluctuations at the end of inflation in some specific two-field models of inflation, a class of which is motivated by hybrid inflation. We demonstrate that there can indeed be a large growth of fluctuations due to parametric resonance and that this effect is not taken into account by the conventional theory of isocurvature perturbations. Scalar field interactions play a crucial role in this analysis. We discuss the conditions under which there can be nontrivial parametric resonance effects on large scales

Optimal Design of Experiments for Parametric Identification of Civil Engineering Structures

DEFF Research Database (Denmark)

Kirkegaard, Poul Henning

Optimal Systems of experiments for parametric identification of civil engineering structures is investigated. Design of experiments for parametric identification of dynamic systems is usually done by minimizing a scalar measure, e.g the determinant, the trace ect., of an estimated parameter...

Sparse-grid, reduced-basis Bayesian inversion: Nonaffine-parametric nonlinear equations

Energy Technology Data Exchange (ETDEWEB)

Chen, Peng, E-mail: peng@ices.utexas.edu [The Institute for Computational Engineering and Sciences, The University of Texas at Austin, 201 East 24th Street, Stop C0200, Austin, TX 78712-1229 (United States); Schwab, Christoph, E-mail: christoph.schwab@sam.math.ethz.ch [Seminar für Angewandte Mathematik, Eidgenössische Technische Hochschule, Römistrasse 101, CH-8092 Zürich (Switzerland)

2016-07-01

We extend the reduced basis (RB) accelerated Bayesian inversion methods for affine-parametric, linear operator equations which are considered in [16,17] to non-affine, nonlinear parametric operator equations. We generalize the analysis of sparsity of parametric forward solution maps in [20] and of Bayesian inversion in [48,49] to the fully discrete setting, including Petrov–Galerkin high-fidelity (“HiFi”) discretization of the forward maps. We develop adaptive, stochastic collocation based reduction methods for the efficient computation of reduced bases on the parametric solution manifold. The nonaffinity and nonlinearity with respect to (w.r.t.) the distributed, uncertain parameters and the unknown solution is collocated; specifically, by the so-called Empirical Interpolation Method (EIM). For the corresponding Bayesian inversion problems, computational efficiency is enhanced in two ways: first, expectations w.r.t. the posterior are computed by adaptive quadratures with dimension-independent convergence rates proposed in [49]; the present work generalizes [49] to account for the impact of the PG discretization in the forward maps on the convergence rates of the Quantities of Interest (QoI for short). Second, we propose to perform the Bayesian estimation only w.r.t. a parsimonious, RB approximation of the posterior density. Based on the approximation results in [49], the infinite-dimensional parametric, deterministic forward map and operator admit N-term RB and EIM approximations which converge at rates which depend only on the sparsity of the parametric forward map. In several numerical experiments, the proposed algorithms exhibit dimension-independent convergence rates which equal, at least, the currently known rate estimates for N-term approximation. We propose to accelerate Bayesian estimation by first offline construction of reduced basis surrogates of the Bayesian posterior density. The parsimonious surrogates can then be employed for online data

Parametric excitation of drift waves in a sheared slab geometry

International Nuclear Information System (INIS)

Vranjes, J.; Weiland, J.

1992-01-01

The threshold for parametric excitation of drift waves in a sheared slab geometry is calculated for a pump wave that is a standing wave along the magnetic field, using the Hasegawa-Mima nonlinearity. The shear damping is counteracted by the parametric coupling and the eigenvalue problem is solved analytically using Taylor's strong coupling approximation. (au)

Brownian parametric oscillators

Science.gov (United States)

Zerbe, Christine; Jung, Peter; Hänggi, Peter

1994-05-01

We discuss the stochastic dynamics of dissipative, white-noise-driven Floquet oscillators, characterized by a time-periodic stiffness. Thus far, little attention has been paid to these exactly solvable nonstationary systems, although they carry a rich potential for several experimental applications. Here, we calculate and discuss the mean values and variances, as well as the correlation functions and the Floquet spectrum. As one main result, we find for certain parameter values that the fluctuations of the position coordinate are suppressed as compared to the equilibrium value of a harmonic oscillator (parametric squeezing).

Parametric estimation for reinforced concrete relief shelter for Aceh cases

Science.gov (United States)

Atthaillah; Saputra, Eri; Iqbal, Muhammad

2018-05-01

This paper was a work in progress (WIP) to discover a rapid parametric framework for post-disaster permanent shelter’s materials estimation. The intended shelters were reinforced concrete construction with bricks as its wall. Inevitably, in post-disaster cases, design variations were needed to help suited victims condition. It seemed impossible to satisfy a beneficiary with a satisfactory design utilizing the conventional method. This study offered a parametric framework to overcome slow construction-materials estimation issue against design variations. Further, this work integrated parametric tool, which was Grasshopper to establish algorithms that simultaneously model, visualize, calculate and write the calculated data to a spreadsheet in a real-time. Some customized Grasshopper components were created using GHPython scripting for a more optimized algorithm. The result from this study was a partial framework that successfully performed modeling, visualization, calculation and writing the calculated data simultaneously. It meant design alterations did not escalate time needed for modeling, visualization, and material estimation. Further, the future development of the parametric framework will be made open source.

Parametric resonance in the early Universe—a fitting analysis

Energy Technology Data Exchange (ETDEWEB)

Figueroa, Daniel G. [Theoretical Physics Department, CERN, Geneva (Switzerland); Torrentí, Francisco, E-mail: daniel.figueroa@cern.ch, E-mail: f.torrenti@csic.es [Instituto de Física Teórica IFT-UAM/CSIC, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid (Spain)

2017-02-01

Particle production via parametric resonance in the early Universe, is a non-perturbative, non-linear and out-of-equilibrium phenomenon. Although it is a well studied topic, whenever a new scenario exhibits parametric resonance, a full re-analysis is normally required. To avoid this tedious task, many works present often only a simplified linear treatment of the problem. In order to surpass this circumstance in the future, we provide a fitting analysis of parametric resonance through all its relevant stages: initial linear growth, non-linear evolution, and relaxation towards equilibrium. Using lattice simulations in an expanding grid in 3+1 dimensions, we parametrize the dynamics' outcome scanning over the relevant ingredients: role of the oscillatory field, particle coupling strength, initial conditions, and background expansion rate. We emphasize the inaccuracy of the linear calculation of the decay time of the oscillatory field, and propose a more appropriate definition of this scale based on the subsequent non-linear dynamics. We provide simple fits to the relevant time scales and particle energy fractions at each stage. Our fits can be applied to post-inflationary preheating scenarios, where the oscillatory field is the inflaton, or to spectator-field scenarios, where the oscillatory field can be e.g. a curvaton, or the Standard Model Higgs.

Parametric resonance in the early Universe—a fitting analysis

International Nuclear Information System (INIS)

Figueroa, Daniel G.; Torrentí, Francisco

2017-01-01

Particle production via parametric resonance in the early Universe, is a non-perturbative, non-linear and out-of-equilibrium phenomenon. Although it is a well studied topic, whenever a new scenario exhibits parametric resonance, a full re-analysis is normally required. To avoid this tedious task, many works present often only a simplified linear treatment of the problem. In order to surpass this circumstance in the future, we provide a fitting analysis of parametric resonance through all its relevant stages: initial linear growth, non-linear evolution, and relaxation towards equilibrium. Using lattice simulations in an expanding grid in 3+1 dimensions, we parametrize the dynamics' outcome scanning over the relevant ingredients: role of the oscillatory field, particle coupling strength, initial conditions, and background expansion rate. We emphasize the inaccuracy of the linear calculation of the decay time of the oscillatory field, and propose a more appropriate definition of this scale based on the subsequent non-linear dynamics. We provide simple fits to the relevant time scales and particle energy fractions at each stage. Our fits can be applied to post-inflationary preheating scenarios, where the oscillatory field is the inflaton, or to spectator-field scenarios, where the oscillatory field can be e.g. a curvaton, or the Standard Model Higgs.

High frequency parametric wave phenomena and plasma heating: a review

International Nuclear Information System (INIS)

Porkolab, M.

1975-11-01

A survey of parametric instabilities in plasma, and associated particle heating, is presented. A brief summary of linear theory is given. The physical mechanism of decay instability, the purely growing mode (oscillating two-stream instability) and soliton and density cavity formation is presented. Effects of density gradients are discussed. Possible nonlinear saturation mechanisms are pointed out. Experimental evidence for the existence of parametric instabilities in both unmagnetized and magnetized plasmas is reviewed in some detail. Experimental observation of plasma heating associated with the presence of parametric instabilities is demonstrated by a number of examples. Possible application of these phenomena to heating of pellets by lasers and heating of magnetically confined fusion plasmas by high power microwave sources is discussed

Robust and Efficient Parametric Face Alignment

NARCIS (Netherlands)

Tzimiropoulos, Georgios; Zafeiriou, Stefanos; Pantic, Maja

2011-01-01

We propose a correlation-based approach to parametric object alignment particularly suitable for face analysis applications which require efficiency and robustness against occlusions and illumination changes. Our algorithm registers two images by iteratively maximizing their correlation coefficient

Simulation-based optimization parametric optimization techniques and reinforcement learning

CERN Document Server

Gosavi, Abhijit

2003-01-01

Simulation-Based Optimization: Parametric Optimization Techniques and Reinforcement Learning introduces the evolving area of simulation-based optimization. The book's objective is two-fold: (1) It examines the mathematical governing principles of simulation-based optimization, thereby providing the reader with the ability to model relevant real-life problems using these techniques. (2) It outlines the computational technology underlying these methods. Taken together these two aspects demonstrate that the mathematical and computational methods discussed in this book do work. Broadly speaking, the book has two parts: (1) parametric (static) optimization and (2) control (dynamic) optimization. Some of the book's special features are: *An accessible introduction to reinforcement learning and parametric-optimization techniques. *A step-by-step description of several algorithms of simulation-based optimization. *A clear and simple introduction to the methodology of neural networks. *A gentle introduction to converg...

Parametric feedback cooling of a single atom inside on optical cavity

International Nuclear Information System (INIS)

Tatjana Wilk

2014-01-01

An optical cavity can be used as a kind of intensifier to study radiation features of an atom, which are hard to detect in free space, like squeezing. Such experiments make use of strong coupling between atom and cavity mode, which experimentally requires the atom to be well localized in the cavity mode. This can be achieved using feedback on the atomic motion: from intensity variations of a probe beam transmitted through the cavity information about the atomic motion is gained, which is used to synchronously modulate the trapping potential holding the atom, leading to cooling and better localization. Here, we report on efficient parametric feedback cooling of a single atom held in an intra-cavity standing wave dipole trap. In contrast to previous feedback strategies, this scheme cools the fast axial oscillation of the atom as well as the slower radial motion. (author)

Parametric Design in Timber Gridshell Tectonics

Directory of Open Access Journals (Sweden)

Ismailiyah Al Athas Syarifah

2018-01-01

Full Text Available This paper begins with a simple proposition: rather than mimicking the geometric structures found in nature, perhaps the most effective modes of sustainable fabrication can be found throughunderstanding the nature of materials themselves. The material becomes a design parameter through the constraints of fabrication tools, limitations of material size, and most importantly the productivecapacity of material resistance a given material’s capacity and tendencies to take shape, rather than cutting shape out of material. Gridshell structures provide an intriguing case study to pursue this proposition. Not only is there clear precedent in the form finding experiments of frei Otto and the institute for lightweight structures, but also the very nurbs based tools of current design practices developed from the ability of wood to bend. Taking the bent wood spline quite literally, gridshells provide a means that is at once formally expressive, structurally optimized, materially efficient, and quite simply a delight to experience. The the larger motivation of this work anticipates a parametric system linking the intrinsic material values of the gridshell tectonic with extrinsic criteria such as programmatic needs and environmental response. Through an applied case study of gridshells, the play between form and material is tested out through the author’s own experimentation with gridshells and the pedagogical results of two gridshell studios.The goal of this research is to establish a give and take relationship between top down formal emphasis and a bottom-up material influence.

Supercritical nonlinear parametric dynamics of Timoshenko microbeams

Science.gov (United States)

Farokhi, Hamed; Ghayesh, Mergen H.

2018-06-01

The nonlinear supercritical parametric dynamics of a Timoshenko microbeam subject to an axial harmonic excitation force is examined theoretically, by means of different numerical techniques, and employing a high-dimensional analysis. The time-variant axial load is assumed to consist of a mean value along with harmonic fluctuations. In terms of modelling, a continuous expression for the elastic potential energy of the system is developed based on the modified couple stress theory, taking into account small-size effects; the kinetic energy of the system is also modelled as a continuous function of the displacement field. Hamilton's principle is employed to balance the energies and to obtain the continuous model of the system. Employing the Galerkin scheme along with an assumed-mode technique, the energy terms are reduced, yielding a second-order reduced-order model with finite number of degrees of freedom. A transformation is carried out to convert the second-order reduced-order model into a double-dimensional first order one. A bifurcation analysis is performed for the system in the absence of the axial load fluctuations. Moreover, a mean value for the axial load is selected in the supercritical range, and the principal parametric resonant response, due to the time-variant component of the axial load, is obtained - as opposed to transversely excited systems, for parametrically excited system (such as our problem here), the nonlinear resonance occurs in the vicinity of twice any natural frequency of the linear system; this is accomplished via use of the pseudo-arclength continuation technique, a direct time integration, an eigenvalue analysis, and the Floquet theory for stability. The natural frequencies of the system prior to and beyond buckling are also determined. Moreover, the effect of different system parameters on the nonlinear supercritical parametric dynamics of the system is analysed, with special consideration to the effect of the length-scale parameter.

Pi-kinks in a parametrically driven sine-Gordon chain

DEFF Research Database (Denmark)

Kivshar, Yuri S.; Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

1992-01-01

We consider the sine-Gordon chain driven by a high-frequency parametric force in the presence of loss. Using an analytical approach based on the method of averaging in fast oscillations, we predict that such a parametric force may support propagation of π kinks, which are unstable in the standard...... sine-Gordon model. The steady-state velocity of the π kinks is calculated, and the analytical results are in good agreement with direct numerical simulations....

APT cost scaling: Preliminary indications from a Parametric Costing Model (PCM)

International Nuclear Information System (INIS)

Krakowski, R.A.

1995-01-01

A Parametric Costing Model has been created and evaluate as a first step in quantitatively understanding important design options for the Accelerator Production of Tritium (APT) concept. This model couples key economic and technical elements of APT in a two-parameter search of beam energy and beam power that minimizes costs within a range of operating constraints. The costing and engineering depth of the Parametric Costing Model is minimal at the present open-quotes entry levelclose quotes, and is intended only to demonstrate a potential for a more-detailed, cost-based integrating design tool. After describing the present basis of the Parametric Costing Model and giving an example of a single parametric scaling run derived therefrom, the impacts of choices related to resistive versus superconducting accelerator structures and cost of electricity versus plant availability (open-quotes load curveclose quotes) are reported. Areas of further development and application are suggested

Parametric Study Of Window Frame Geometry

DEFF Research Database (Denmark)

Zajas, Jan Jakub; Heiselberg, Per

2013-01-01

This paper describes a parametric study on window frame geometry with the goal of designing frames with very good thermal properties. Three different parametric frame models are introduced, deseribed by a number of variables. In the first part of the study, a process of sensitivity analysis...... is conducted to determine which of the parameters describing the frame have the highest impact on its thermal performance. Afterwards, an optimization process is conducted on each frame in order to optimize the design with regard to three objectives: minimizing the thermal transmittance, maxim izing the net...... energy gain factor and minimizing the material use. Since the objectives contradiet each other, it was found that it is not possible to identifY a single solution that satisfies all these goals. lnstead, a compromise between the objectives has to be found....

Calculation of the Nucleon Axial Form Factor Using Staggered Lattice QCD

Energy Technology Data Exchange (ETDEWEB)

Meyer, Aaron S. [Fermilab; Hill, Richard J. [Perimeter Inst. Theor. Phys.; Kronfeld, Andreas S. [Fermilab; Li, Ruizi [Indiana U.; Simone, James N. [Fermilab

2016-10-14

The nucleon axial form factor is a dominant contribution to errors in neutrino oscillation studies. Lattice QCD calculations can help control theory errors by providing first-principles information on nucleon form factors. In these proceedings, we present preliminary results on a blinded calculation of $g_A$ and the axial form factor using HISQ staggered baryons with 2+1+1 flavors of sea quarks. Calculations are done using physical light quark masses and are absolutely normalized. We discuss fitting form factor data with the model-independent $z$ expansion parametrization.

Parametric resonance in superconducting micron-scale waveguides

International Nuclear Information System (INIS)

Fomin, N.V.; Shalaev, O.L.; Shantsev, D.V.

1997-01-01

A parametric resonance due to temperature oscillations in superconducting micron-scale waveguides is considered. Oscillations of superconductor temperature are assumed to be induced by the irradiation of the waveguide with a laser beam. The laser power and parameters of the waveguide providing a possibility of parametric excitation have been calculated. It is shown that for a waveguide made of a YBa 2 Cu 3 O 7 microstrip with resonant frequency of 10 GHz a laser with a power of about 70 W/cm 2 is needed to excite oscillations. The effect can be used for the creation of high-sensitivity tuneable filters and optoelectric transformers on superconducting microstrips in the GHz range. copyright 1997 American Institute of Physics

[Endurance training in hypertension is effective. Which form of sports, frequency and intensity of training? When should adjuvant chemotherapy be considered?].

Science.gov (United States)

Ketelhut, R G

1998-12-10

Physical activity in the form of endurance training is highly recommendable for hypertensives. Both suitable and unsuitable forms of sports are identified. From various points of view, two one-hour sessions per week would appear to be optimal. The intensity of the activity should be oriented to the heart rate, and, for safety's sake, prior ergometric evaluation should be carried out. As a rule of thumb, the heart rate should not exceed 70% of the maximum rate during exercise. If the blood pressure should nevertheless increase too much, appropriate pharmacological treatment is indicated.

Interdisciplinary parametric design : The XXL experience

NARCIS (Netherlands)

Turrin, M.; Sariyildiz, I.S.; Paul, J.C.

2015-01-01

Focusing on large span structures for sport buildings, the paper tackles the role of parametric modelling and performance simulations, to enhance the integration between architectural and engineering design. The general approach contrasts post-engineering processes. In post-engineering, technical

Applied CATIA Secondary Development to Parametric Design of Active Magnetic Bearing

Directory of Open Access Journals (Sweden)

Zhang Li

2016-01-01

Full Text Available Based on the properties of active magnetic bearing, the electromagnetic parameters and structure parameters are analyzed, parametric design method is introduced to study the structure of active magnetic bearing. Through a program personalization process that is in accordance with active magnetic bearing is established. Personalization process aims to build the parametric model of active magnetic bearings and component library by use of CATIA secondary development. Component library is to build assembly model for a multiple degree of freedom magnetic bearing system. Parametric design is a method that provides the direction for its structural design.

Sgr A* Emission Parametrizations from GRMHD Simulations

Science.gov (United States)

Anantua, Richard; Ressler, Sean; Quataert, Eliot

2018-06-01

Galactic Center emission near the vicinity of the central black hole, Sagittarius (Sgr) A*, is modeled using parametrizations involving the electron temperature, which is found from general relativistic magnetohydrodynamic (GRMHD) simulations to be highest in the disk-outflow corona. Jet-motivated prescriptions generalizing equipartition of particle and magnetic energies, e.g., by scaling relativistic electron energy density to powers of the magnetic field strength, are also introduced. GRMHD jet (or outflow)/accretion disk/black hole (JAB) simulation postprocessing codes IBOTHROS and GRMONTY are employed in the calculation of images and spectra. Various parametric models reproduce spectral and morphological features, such as the sub-mm spectral bump in electron temperature models and asymmetric photon rings in equipartition-based models. The Event Horizon Telescope (EHT) will provide unprecedentedly high-resolution 230+ GHz observations of the "shadow" around Sgr A*'s supermassive black hole, which the synthetic models presented here will reverse-engineer. Both electron temperature and equipartition-based models can be constructed to be compatible with EHT size constraints for the emitting region of Sgr A*. This program sets the groundwork for devising a unified emission parametrization flexible enough to model disk, corona and outflow/jet regions with a small set of parameters including electron heating fraction and plasma beta.

On the phase form of a deformation quantization with separation of variables

OpenAIRE

Karabegov, Alexander

2015-01-01

Given a star product with separation of variables on a pseudo-Kaehler manifold, we obtain a new formal (1,1)-form from its classifying form and call it the phase form of the star product. The cohomology class of a star product with separation of variables equals the class of its phase form. We show that the phase forms can be arbitrary and they bijectively parametrize the star products with separation of variables. We also describe the action of a change of the formal parameter on a star prod...

Metastable states in parametrically excited multimode Hamiltonian systems

CERN Document Server

Kirr, E

2003-01-01

Consider a linear autonomous Hamiltonian system with time periodic bound state solutions. In this paper we study their dynamics under time almost periodic perturbations which are small, localized and Hamiltonian. The analysis proceeds through a reduction of the original infinite dimensional dynamical system to the dynamics of two coupled subsystems: a dominant m-dimensional system of ordinary differential equations (normal form), governing the projections onto the bound states and an infinite dimensional dispersive wave equation. The present work generalizes previous work of the authors, where the case of a single bound state is considered. Here, the interaction picture is considerably more complicated and requires deeper analysis, due to a multiplicity of bound states and the very general nature of the perturbation's time dependence. Parametric forcing induces coupling of bound states to continuum radiation modes, bound states directly to bound states, as well as coupling among bound states, which is mediate...

Parametric estimation in the wave buoy analogy - an elaborated approach based on energy considerations

DEFF Research Database (Denmark)

Montazeri, Najmeh; Nielsen, Ulrik Dam

2014-01-01

the ship’s wave-induced responses based on different statistical inferences including parametric and non-parametric approaches. This paper considers a concept to improve the estimate obtained by the parametric method for sea state estimation. The idea is illustrated by an analysis made on full-scale...

Parametric programming of industrial robots

Directory of Open Access Journals (Sweden)

Szulczyński Paweł

2015-06-01

Full Text Available This article proposes the use of parametric design software, commonly used by architects, in order to obtain complex trajectory and program code for industrial robots. The paper describes the drawbacks of existing solutions and proposes a new script to obtain a correct program. The result of the algorithm was verified experimentally.

Multi-parametric variational data assimilation for hydrological forecasting

Science.gov (United States)

Alvarado-Montero, R.; Schwanenberg, D.; Krahe, P.; Helmke, P.; Klein, B.

2017-12-01

Ensemble forecasting is increasingly applied in flow forecasting systems to provide users with a better understanding of forecast uncertainty and consequently to take better-informed decisions. A common practice in probabilistic streamflow forecasting is to force deterministic hydrological model with an ensemble of numerical weather predictions. This approach aims at the representation of meteorological uncertainty but neglects uncertainty of the hydrological model as well as its initial conditions. Complementary approaches use probabilistic data assimilation techniques to receive a variety of initial states or represent model uncertainty by model pools instead of single deterministic models. This paper introduces a novel approach that extends a variational data assimilation based on Moving Horizon Estimation to enable the assimilation of observations into multi-parametric model pools. It results in a probabilistic estimate of initial model states that takes into account the parametric model uncertainty in the data assimilation. The assimilation technique is applied to the uppermost area of River Main in Germany. We use different parametric pools, each of them with five parameter sets, to assimilate streamflow data, as well as remotely sensed data from the H-SAF project. We assess the impact of the assimilation in the lead time performance of perfect forecasts (i.e. observed data as forcing variables) as well as deterministic and probabilistic forecasts from ECMWF. The multi-parametric assimilation shows an improvement of up to 23% for CRPS performance and approximately 20% in Brier Skill Scores with respect to the deterministic approach. It also improves the skill of the forecast in terms of rank histogram and produces a narrower ensemble spread.

Nonlinear Container Ship Model for the Study of Parametric Roll Resonance

DEFF Research Database (Denmark)

Holden, Christian; Galeazzi, Roberto; Rodríguez, Claudio

2007-01-01

Parametric roll is a critical phenomenon for ships, whose onset may cause roll oscillations up to 40, leading to very dangerous situations and possibly capsizing. Container ships have been shown to be particularly prone to parametric roll resonance when they are sailing in moderate to heavy head ...

Parametric excitation of a SiN membrane via piezoelectricity

Directory of Open Access Journals (Sweden)

Shuhui Wu

2018-01-01

Full Text Available We develop a stoichiometric silicon nitride (SiN membrane-based electromechanical system, in which the spring constant of the mechanical resonator can be dynamically controlled via piezoelectric actuation. The degenerate parametric amplifier is studied in this configuration. We observe the splitting of mechanical mode in the response spectra of a phase-sensitive parametric amplifier. In addition, we demonstrate that the quality factor Q of the membrane oscillator can be significantly enhanced by more than two orders of magnitude due to the coherent amplification, reaching an effective Q factor of ∼3 × 108 at room temperature. The nonlinear effect on the parametric amplification is also investigated, as well as the thermomechanical noise squeezing. This system offers the possibility to integrate electrical, optical and mechanical degrees of freedom without compromising the exceptional material properties of SiN membranes, and can be a useful platform for studying cavity optoelectromechanics.

Parametric excitation of a SiN membrane via piezoelectricity

Science.gov (United States)

Wu, Shuhui; Sheng, Jiteng; Zhang, Xiaotian; Wu, Yuelong; Wu, Haibin

2018-01-01

We develop a stoichiometric silicon nitride (SiN) membrane-based electromechanical system, in which the spring constant of the mechanical resonator can be dynamically controlled via piezoelectric actuation. The degenerate parametric amplifier is studied in this configuration. We observe the splitting of mechanical mode in the response spectra of a phase-sensitive parametric amplifier. In addition, we demonstrate that the quality factor Q of the membrane oscillator can be significantly enhanced by more than two orders of magnitude due to the coherent amplification, reaching an effective Q factor of ˜3 × 108 at room temperature. The nonlinear effect on the parametric amplification is also investigated, as well as the thermomechanical noise squeezing. This system offers the possibility to integrate electrical, optical and mechanical degrees of freedom without compromising the exceptional material properties of SiN membranes, and can be a useful platform for studying cavity optoelectromechanics.

Observation of parametric X-ray radiation by an imaging plate

International Nuclear Information System (INIS)

Takabayashi, Y.; Shchagin, A.V.

2012-01-01

We have demonstrated experimentally the application of an imaging plate for registering the angular distribution of parametric X-ray radiation. The imaging plate was used as a two-dimensional position-sensitive X-ray detector. High-quality images of the fine structure in the angular distributions of the yield around the reflection of the parametric X-ray radiation produced in a silicon crystal by a 255-MeV electron beam from a linear accelerator have been observed in the Laue geometry. A fairly good agreement between results of measurements and calculations by the kinematic theory of parametric X-ray radiation is shown. Applications of the imaging plates for the observation of the angular distribution of X-rays produced by accelerated particles in a crystal are also discussed.

Nonlinear Container Ship Model for the Study of Parametric Roll Resonance

Directory of Open Access Journals (Sweden)

Christian Holden

2007-10-01

Full Text Available Parametric roll is a critical phenomenon for ships, whose onset may cause roll oscillations up to +-40 degrees, leading to very dangerous situations and possibly capsizing. Container ships have been shown to be particularly prone to parametric roll resonance when they are sailing in moderate to heavy head seas. A Matlab/Simulink parametric roll benchmark model for a large container ship has been implemented and validated against a wide set of experimental data. The model is a part of a Matlab/Simulink Toolbox (MSS, 2007. The benchmark implements a 3rd-order nonlinear model where the dynamics of roll is strongly coupled with the heave and pitch dynamics. The implemented model has shown good accuracy in predicting the container ship motions, both in the vertical plane and in the transversal one. Parametric roll has been reproduced for all the data sets in which it happened, and the model provides realistic results which are in good agreement with the model tank experiments.

HELIOS: A high intensity chopper spectrometer at LANSCE

International Nuclear Information System (INIS)

Mason, T.E.; Broholm, C.; Fultz, B.

1998-01-01

A proposal to construct a high intensity chopper spectrometer at LANSCE as part of the SPSS upgrade project is discussed. HELIOS will be optimized for science requiring high sensitivity neutron spectroscopy. This includes studies of phonon density of states in small polycrystalline samples, magnetic excitations in quantum magnets and highly correlated electron systems, as well as parametric studies (as a function of pressure, temperature, or magnetic field) of S(Q,ω). By employing a compact design together with the use of supermirror guide in the incident flight path the neutron flux at HELIOS will be significantly higher than any other comparable instrument now operating

HELIOS: A high intensity chopper spectrometer at LANSCE

Energy Technology Data Exchange (ETDEWEB)

Mason, T.E. [Oak Ridge National Lab., TN (United States); Broholm, C. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Physics and Astronomy; Fultz, B. [California Inst. of Tech., Pasadena, CA (United States). Dept. of Materials Science] [and others

1998-12-31

A proposal to construct a high intensity chopper spectrometer at LANSCE as part of the SPSS upgrade project is discussed. HELIOS will be optimized for science requiring high sensitivity neutron spectroscopy. This includes studies of phonon density of states in small polycrystalline samples, magnetic excitations in quantum magnets and highly correlated electron systems, as well as parametric studies (as a function of pressure, temperature, or magnetic field) of S(Q,{omega}). By employing a compact design together with the use of supermirror guide in the incident flight path the neutron flux at HELIOS will be significantly higher than any other comparable instrument now operating.

Experimental observation of parametric instabilities at laser intensities relevant for shock ignition

Czech Academy of Sciences Publication Activity Database

Cristoforetti, G.; Colaïtis, A.; Antonelli, L.; Atzeni, S.; Baffigi, F.; Batani, D.; Barbato, F.; Boutoux, G.; Dudžák, Roman; Koester, P.; Krouský, Eduard; Labate, L.; Nicolaï, P.; Renner, Oldřich; Skoric, M.; Tikhonchuk, V.; Gizzi, L.A.

2017-01-01

Roč. 117, č. 3 (2017), č. článku 35001. ISSN 0295-5075 R&D Projects: GA MŠk(CZ) LC528; GA MŠk LM2010014; GA MŠk EF15_008/0000162 EU Projects: European Commission(XE) 633053 - EUROfusion Grant - others:EU - ICT(XE) COST Action IC1208; ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:61389021 ; RVO:68378271 Keywords : laser intensity regime * Stimulated Brillouin Scattering (SBS) * Stimulated Raman Scattering (SRS) * Two-Plasmon Decay (TPD) Subject RIV: BL - Plasma and Gas Discharge Physics; BL - Plasma and Gas Discharge Physics (FZU-D) OBOR OECD: Fluids and plasma physics (including surface physics); Fluids and plasma physics (including surface physics) (FZU-D) Impact factor: 1.957, year: 2016 https://doi.org/10.1209/0295-5075/117/35001

Ranking Forestry Investments With Parametric Linear Programming

Science.gov (United States)

Paul A. Murphy

1976-01-01

Parametric linear programming is introduced as a technique for ranking forestry investments under multiple constraints; it combines the advantages of simple tanking and linear programming as capital budgeting tools.

Further Empirical Results on Parametric Versus Non-Parametric IRT Modeling of Likert-Type Personality Data

Science.gov (United States)

Maydeu-Olivares, Albert

2005-01-01

Chernyshenko, Stark, Chan, Drasgow, and Williams (2001) investigated the fit of Samejima's logistic graded model and Levine's non-parametric MFS model to the scales of two personality questionnaires and found that the graded model did not fit well. We attribute the poor fit of the graded model to small amounts of multidimensionality present in…

SU-G-JeP2-02: A Unifying Multi-Atlas Approach to Electron Density Mapping Using Multi-Parametric MRI for Radiation Treatment Planning

Energy Technology Data Exchange (ETDEWEB)

Ren, S [Stanford University, Stanford, CA (United States); Tianjin University, Tianjin (China); Hara, W; Le, Q; Wang, L; Xing, L; Li, R [Stanford University, Stanford, CA (United States)

2016-06-15

Purpose: MRI has a number of advantages over CT as a primary modality for radiation treatment planning (RTP). However, one key bottleneck problem still remains, which is the lack of electron density information in MRI. In the work, a reliable method to map electron density is developed by leveraging the differential contrast of multi-parametric MRI. Methods: We propose a probabilistic Bayesian approach for electron density mapping based on T1 and T2-weighted MRI, using multiple patients as atlases. For each voxel, we compute two conditional probabilities: (1) electron density given its image intensity on T1 and T2-weighted MR images, and (2) electron density given its geometric location in a reference anatomy. The two sources of information (image intensity and spatial location) are combined into a unifying posterior probability density function using the Bayesian formalism. The mean value of the posterior probability density function provides the estimated electron density. Results: We evaluated the method on 10 head and neck patients and performed leave-one-out cross validation (9 patients as atlases and remaining 1 as test). The proposed method significantly reduced the errors in electron density estimation, with a mean absolute HU error of 138, compared with 193 for the T1-weighted intensity approach and 261 without density correction. For bone detection (HU>200), the proposed method had an accuracy of 84% and a sensitivity of 73% at specificity of 90% (AUC = 87%). In comparison, the AUC for bone detection is 73% and 50% using the intensity approach and without density correction, respectively. Conclusion: The proposed unifying method provides accurate electron density estimation and bone detection based on multi-parametric MRI of the head with highly heterogeneous anatomy. This could allow for accurate dose calculation and reference image generation for patient setup in MRI-based radiation treatment planning.

SU-G-JeP2-02: A Unifying Multi-Atlas Approach to Electron Density Mapping Using Multi-Parametric MRI for Radiation Treatment Planning

International Nuclear Information System (INIS)

Ren, S; Hara, W; Le, Q; Wang, L; Xing, L; Li, R

2016-01-01

Purpose: MRI has a number of advantages over CT as a primary modality for radiation treatment planning (RTP). However, one key bottleneck problem still remains, which is the lack of electron density information in MRI. In the work, a reliable method to map electron density is developed by leveraging the differential contrast of multi-parametric MRI. Methods: We propose a probabilistic Bayesian approach for electron density mapping based on T1 and T2-weighted MRI, using multiple patients as atlases. For each voxel, we compute two conditional probabilities: (1) electron density given its image intensity on T1 and T2-weighted MR images, and (2) electron density given its geometric location in a reference anatomy. The two sources of information (image intensity and spatial location) are combined into a unifying posterior probability density function using the Bayesian formalism. The mean value of the posterior probability density function provides the estimated electron density. Results: We evaluated the method on 10 head and neck patients and performed leave-one-out cross validation (9 patients as atlases and remaining 1 as test). The proposed method significantly reduced the errors in electron density estimation, with a mean absolute HU error of 138, compared with 193 for the T1-weighted intensity approach and 261 without density correction. For bone detection (HU>200), the proposed method had an accuracy of 84% and a sensitivity of 73% at specificity of 90% (AUC = 87%). In comparison, the AUC for bone detection is 73% and 50% using the intensity approach and without density correction, respectively. Conclusion: The proposed unifying method provides accurate electron density estimation and bone detection based on multi-parametric MRI of the head with highly heterogeneous anatomy. This could allow for accurate dose calculation and reference image generation for patient setup in MRI-based radiation treatment planning.

Narrow linewidth pulsed optical parametric oscillator

Indian Academy of Sciences (India)

Tunable narrow linewidth radiation by optical parametric oscillation has many applications, particularly in spectroscopic investigation. In this paper, different techniques such as injection seeding, use of spectral selecting element like grating, grating and etalon in combination, grazing angle of incidence, entangled cavity ...

Functional Neuroimaging of Emotionally Intense Autobiographical Memories in Post-Traumatic Stress Disorder

Science.gov (United States)

St. Jacques, Peggy L.; Botzung, Anne; Miles, Amanda; Rubin, David C.

2010-01-01

Post-traumatic stress disorder (PTSD) affects regions that support autobiographical memory (AM) retrieval, such as the hippocampus, amygdala and ventral medial prefrontal cortex (PFC). However, it is not well understood how PTSD may impact the neural mechanisms of memory retrieval for the personal past. We used a generic cue method combined with parametric modulation analysis and functional MRI (fMRI) to investigate the neural mechanisms affected by PTSD symptoms during the retrieval of a large sample of emotionally intense AMs. There were three main results. First, the PTSD group showed greater recruitment of the amygdala/hippocampus during the construction of negative versus positive emotionally intense AMs, when compared to controls. Second, across both the construction and elaboration phases of retrieval the PTSD group showed greater recruitment of the ventral medial PFC for negatively intense memories, but less recruitment for positively intense memories. Third, the PTSD group showed greater functional coupling between the ventral medial PFC and the amygdala for negatively intense memories, but less coupling for positively intense memories. In sum, the fMRI data suggest that there was greater recruitment and coupling of emotional brain regions during the retrieval of negatively intense AMs in the PTSD group when compared to controls. PMID:21109253

Integrating classification trees with local logistic regression in Intensive Care prognosis.

Science.gov (United States)

Abu-Hanna, Ameen; de Keizer, Nicolette

2003-01-01

Health care effectiveness and efficiency are under constant scrutiny especially when treatment is quite costly as in the Intensive Care (IC). Currently there are various international quality of care programs for the evaluation of IC. At the heart of such quality of care programs lie prognostic models whose prediction of patient mortality can be used as a norm to which actual mortality is compared. The current generation of prognostic models in IC are statistical parametric models based on logistic regression. Given a description of a patient at admission, these models predict the probability of his or her survival. Typically, this patient description relies on an aggregate variable, called a score, that quantifies the severity of illness of the patient. The use of a parametric model and an aggregate score form adequate means to develop models when data is relatively scarce but it introduces the risk of bias. This paper motivates and suggests a method for studying and improving the performance behavior of current state-of-the-art IC prognostic models. Our method is based on machine learning and statistical ideas and relies on exploiting information that underlies a score variable. In particular, this underlying information is used to construct a classification tree whose nodes denote patient sub-populations. For these sub-populations, local models, most notably logistic regression ones, are developed using only the total score variable. We compare the performance of this hybrid model to that of a traditional global logistic regression model. We show that the hybrid model not only provides more insight into the data but also has a better performance. We pay special attention to the precision aspect of model performance and argue why precision is more important than discrimination ability.

Phase-matching-free parametric oscillators based on two dimensional semiconductors

OpenAIRE

Ciattoni, A.; Marini, A.; Rizza, C.; Conti, C.

2017-01-01

Optical parametric oscillators are widely-used pulsed and continuous-wave tunable sources for innumerable applications, as in quantum technologies, imaging and biophysics. A key drawback is material dispersion imposing the phase-matching condition that generally entails a complex setup design, thus hindering tunability and miniaturization. Here we show that the burden of phase-matching is surprisingly absent in parametric micro-resonators adopting monolayer transition-metal dichalcogenides as...

Markovian Dynamics of Josephson Parametric Amplification

Directory of Open Access Journals (Sweden)

W. Kaiser

2017-09-01

Full Text Available In this work, we derive the dynamics of the lossy DC pumped non-degenerate Josephson parametric amplifier (DCPJPA. The main element in a DCPJPA is the superconducting Josephson junction. The DC bias generates the AC Josephson current varying the nonlinear inductance of the junction. By this way the Josephson junction acts as the pump oscillator as well as the time varying reactance of the parametric amplifier. In quantum-limited amplification, losses and noise have an increased impact on the characteristics of an amplifier. We outline the classical model of the lossy DCPJPA and derive the available noise power spectral densities. A classical treatment is not capable of including properties like spontaneous emission which is mandatory in case of amplification at the quantum limit. Thus, we derive a quantum mechanical model of the lossy DCPJPA. Thermal losses are modeled by the quantum Langevin approach, by coupling the quantized system to a photon heat bath in thermodynamic equilibrium. The mode occupation in the bath follows the Bose-Einstein statistics. Based on the second quantization formalism, we derive the Heisenberg equations of motion of both resonator modes. We assume the dynamics of the system to follow the Markovian approximation, i.e. the system only depends on its actual state and is memory-free. We explicitly compute the time evolution of the contributions to the signal mode energy and give numeric examples based on different damping and coupling constants. Our analytic results show, that this model is capable of including thermal noise into the description of the DC pumped non-degenerate Josephson parametric amplifier.

Markovian Dynamics of Josephson Parametric Amplification

Science.gov (United States)

Kaiser, Waldemar; Haider, Michael; Russer, Johannes A.; Russer, Peter; Jirauschek, Christian

2017-09-01

In this work, we derive the dynamics of the lossy DC pumped non-degenerate Josephson parametric amplifier (DCPJPA). The main element in a DCPJPA is the superconducting Josephson junction. The DC bias generates the AC Josephson current varying the nonlinear inductance of the junction. By this way the Josephson junction acts as the pump oscillator as well as the time varying reactance of the parametric amplifier. In quantum-limited amplification, losses and noise have an increased impact on the characteristics of an amplifier. We outline the classical model of the lossy DCPJPA and derive the available noise power spectral densities. A classical treatment is not capable of including properties like spontaneous emission which is mandatory in case of amplification at the quantum limit. Thus, we derive a quantum mechanical model of the lossy DCPJPA. Thermal losses are modeled by the quantum Langevin approach, by coupling the quantized system to a photon heat bath in thermodynamic equilibrium. The mode occupation in the bath follows the Bose-Einstein statistics. Based on the second quantization formalism, we derive the Heisenberg equations of motion of both resonator modes. We assume the dynamics of the system to follow the Markovian approximation, i.e. the system only depends on its actual state and is memory-free. We explicitly compute the time evolution of the contributions to the signal mode energy and give numeric examples based on different damping and coupling constants. Our analytic results show, that this model is capable of including thermal noise into the description of the DC pumped non-degenerate Josephson parametric amplifier.

Innovation Intensity and Adoption at the Base of the Pyramid Market: A Study of Household Appliances

Directory of Open Access Journals (Sweden)

Vitor Koki da Costa Nogami

2015-08-01

Full Text Available The paper analyzes the innovation intensity and adoption characteristics at the base of the pyramid market. The innovation intensity is configured as radical and incremental, while the innovation adoption is configured as early and tardy. As an empirical approach it was conducted a study type survey. Data analysis is based on non-parametric statistics. The results indicate that the base of the pyramid consumers is characterized by adopting incremental innovations tardily, as pointed out by the literature. Furthermore, it was also observed that women have greater decision-making power in the families of this segment.

A Novel Parametric Model For The Human Respiratory System

Directory of Open Access Journals (Sweden)

Clara Mihaela IONESCU

2003-12-01

Full Text Available The purpose of this work is to present some recent results in an ongoing research project between Ghent University and Chess Medical Technology Company Belgium. The overall aim of the project is to provide a fast method for identification of the human respiratory system in order to allow for an instantaneously diagnosis of the patient by the medical staff. A novel parametric model of the human respiratory system as well as the obtained experimental results is presented in this paper. A prototype apparatus developed by the company, based on the forced oscillation technique is used to record experimental data from 4 patients in this paper. Signal processing is based on spectral analysis and is followed by the parametric identification of a non-linear mechanistic model. The parametric model is equivalent to the structure of a simple electrical RLC-circuit, containing a non-linear capacitor. These parameters have a useful and easy-to-interpret physical meaning for the medical staff members.

Parametric Resonance in the Early Universe - A Fitting Analysis

CERN Document Server

Figueroa, Daniel G.

2017-02-01

Particle production via parametric resonance in the early Universe, is a non-perturbative, non-linear and out-of-equilibrium phenomenon. Although it is a well studied topic, whenever a new scenario exhibits parametric resonance, a full re-analysis is normally required. To avoid this tedious task, many works present often only a simplified linear treatment of the problem. In order to surpass this circumstance in the future, we provide a fitting analysis of parametric resonance through all its relevant stages: initial linear growth, non-linear evolution, and relaxation towards equilibrium. Using lattice simulations in an expanding grid in $3+1$ dimensions, we parametrise the dynamics' outcome scanning over the relevant ingredients: role of the oscillatory field, particle coupling strength, initial conditions, and background expansion rate. We emphasise the inaccuracy of the linear calculation of the decay time of the oscillatory field, and propose a more appropriate definition of this scale based on the subsequ...

Parametric studies of tandem mirror reactors

International Nuclear Information System (INIS)

Carlson, G.A.; Boghosian, B.M.; Fink, J.H.; Myall, J.O.; Neef, W.S. Jr.

1979-01-01

This report, along with its companion, An Improved Tandem Mirror Reactor, discusses the recent progress and present status of our tandem mirror reactor studies. This report presents the detailed results of parametric studies up to, but not including, the very new ideas involving thermal barriers

Parametric Architectural Design with Point-clouds

DEFF Research Database (Denmark)

Zwierzycki, Mateusz; Evers, Henrik Leander; Tamke, Martin

2016-01-01

This paper investigates the efforts and benefits of the implementation of point clouds into architectural design processes and tools. Based on a study on the principal work processes of designers with point clouds the prototypical plugin/library - Volvox - was developed for the parametric modelling...

Parametric Primitives for Hand Gesture Recognition

DEFF Research Database (Denmark)

Baby, Sanmohan; Krüger, Volker

2009-01-01

Imitation learning is considered to be an effective way of teaching humanoid robots and action recognition is the key step to imitation learning. In this paper  an online algorithm to recognize parametric actions with object context is presented. Objects are key instruments in understanding...

Non-Parametric Estimation of Correlation Functions

DEFF Research Database (Denmark)

Brincker, Rune; Rytter, Anders; Krenk, Steen

In this paper three methods of non-parametric correlation function estimation are reviewed and evaluated: the direct method, estimation by the Fast Fourier Transform and finally estimation by the Random Decrement technique. The basic ideas of the techniques are reviewed, sources of bias are point...

Detuned mechanical parametric amplification as a quantum non-demolition measurement

International Nuclear Information System (INIS)

Szorkovszky, A; Bowen, W P; Clerk, A A; Doherty, A C

2014-01-01

Recently it has been demonstrated that the combination of continuous position detection with detuned parametric driving can lead to significant steady-state mechanical squeezing, far beyond the 3 dB limit normally associated with parametric driving. In this work, we show the close connection between this detuned scheme and quantum non-demolition (QND) measurement of a single mechanical quadrature. In particular, we show that applying an experimentally realistic detuned parametric drive to a cavity optomechanical system allows one to effectively realize a QND measurement despite being in the bad-cavity limit. In the limit of strong squeezing, we show that this scheme offers significant advantages over standard backaction evasion, not only by allowing operation in the weak measurement and low efficiency regimes, but also in terms of the purity of the mechanical state

Compact dispersion relations for parametric instabilities of electromagnetic waves in magnetized plasmas

International Nuclear Information System (INIS)

Cohen, B.I.

1987-01-01

The existence of compact dispersion relations for parametric instabilities of coherent electromagnetic waves in magnetized plasmas is addressed here. In general, comprehensive dispersion relations for parametric instabilities in unmagnetized plasmas become more complicated in the presence of an applied time-independent magnetic field. This is demonstrated with a fluid perturbation theory. A compact dispersion relation for parametric instabilities in unmagnetized plasma is heuristically extended here to the case of a magnetized plasma. This dispersion relation gives the correct results in a variety of circumstances of interest in considering electron cyclotron heating applications

Theory of fluctuations and parametric noise in a point nuclear reactor model

International Nuclear Information System (INIS)

Rodriguez, M.A.; San Miguel, M.; Sancho, J.M.

1984-01-01

We present a joint description of internal fluctuations and parametric noise in a point nuclear reactor model in which delayed neutrons and a detector are considered. We obtain kinetic equations for the first moments and define effective kinetic parameters which take into account the effect of parametric Gaussian white noise. We comment on the validity of Langevin approximations for this problem. We propose a general method to deal with weak but otherwise arbitrary non-white parametric noise. Exact kinetic equations are derived for Gaussian non-white noise. (author)

Low default credit scoring using two-class non-parametric kernel density estimation

CSIR Research Space (South Africa)

Rademeyer, E

2016-12-01

Full Text Available This paper investigates the performance of two-class classification credit scoring data sets with low default ratios. The standard two-class parametric Gaussian and non-parametric Parzen classifiers are extended, using Bayes’ rule, to include either...

Design of a Highly Stable, High-Conversion-Efficiency, Optical Parametric Chirped-Pulse Amplification System with Good Beam Quality

International Nuclear Information System (INIS)

Guardalben, M.J.; Keegan, J.; Waxer, L.J.; Bagnoud, V.; Begishev, I.A.; Puth, J.; Zuegel, J.D.

2003-01-01

OAK B204 An optical parametric chirped-pulse amplifier (OPCPA) design that provides 40% pump-to-signal conversion efficiency and over-500-mJ signal energy at 1054 nm for front-end injection into a Nd:glass amplifier chain is presented. This OPCPA system is currently being built as the prototype front end for the OMEGA EP (extended performance) laser system at the University of Rochester's Laboratory for Laser Energetics. Using a three-dimensional spatial and temporal numerical model, several design considerations necessary to achieve high conversion efficiency, good output stability, and good beam quality are discussed. The dependence of OPCPA output on the pump beam's spatiotemporal shape and the relative size of seed and pump beams is described. This includes the effects of pump intensity modulation and pump-signal walk-off. The trade-off among efficiency, stability, and low output beam intensity modulation is discussed

PARAMETRIC MODEL OF LUMBAR VERTEBRA

Directory of Open Access Journals (Sweden)

CAPPETTI Nicola

2010-11-01

Full Text Available The present work proposes the realization of a parametric/variational CAD model of a normotype lumbar vertebra, which could be used for improving the effectiveness of actual imaging techniques in informational augmentation of the orthopaedic and traumatological diagnosis. In addition it could be used for ergonomic static and dynamical analysis of the lumbar region and vertebral column.

Relational Parametricity and Separation Logic

DEFF Research Database (Denmark)

Birkedal, Lars; Yang, Hongseok

2008-01-01

Separation logic is a recent extension of Hoare logic for reasoning about programs with references to shared mutable data structures. In this paper, we provide a new interpretation of the logic for a programming language with higher types. Our interpretation is based on Reynolds's relational...... parametricity, and it provides a formal connection between separation logic and data abstraction. Udgivelsesdato: 2008...

On the parametric cyclotron heating of a toroidal plasma

International Nuclear Information System (INIS)

Golovanivsky, K.C.; Punithavelu, A.M.

1976-01-01

The possibility of heating the ionic component of a dense plasma at the parametric cyclotron resonance, using a section of the conducting toroidal chamber of a large scale Tokamak as a resonance cavity, is considered. It is suggested to use the mode TE 011 to overcome the difficulties with the penetration of HF fields into such a dense plasma. The experimental investigation of parametric cyclotron heating of electrons in a overdense plasma (n/nsub(cut off)=10 2 ) on such a model has given hopeful results

Pulse Distortion in Saturated Fiber Optical Parametric Chirped Pulse Amplification

DEFF Research Database (Denmark)

Lali-Dastjerdi, Zohreh; Da Ros, Francesco; Rottwitt, Karsten

2012-01-01

Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation.......Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation....

On the phase form of a deformation quantization with separation of variables

Science.gov (United States)

Karabegov, Alexander

2016-06-01

Given a star product with separation of variables on a pseudo-Kähler manifold, we obtain a new formal (1, 1)-form from its classifying form and call it the phase form of the star product. The cohomology class of a star product with separation of variables equals the class of its phase form. We show that the phase forms can be arbitrary and they bijectively parametrize the star products with separation of variables. We also describe the action of a change of the formal parameter on a star product with separation of variables, its formal Berezin transform, classifying form, phase form, and canonical trace density.

Probabilistic Reachability for Parametric Markov Models

DEFF Research Database (Denmark)

Hahn, Ernst Moritz; Hermanns, Holger; Zhang, Lijun

2011-01-01

Given a parametric Markov model, we consider the problem of computing the rational function expressing the probability of reaching a given set of states. To attack this principal problem, Daws has suggested to first convert the Markov chain into a finite automaton, from which a regular expression...

On the parametrization of the Δ residue function

International Nuclear Information System (INIS)

Vasan, S.S.

1976-01-01

The complex residues at the Δ(1236) and Δ(1950) poles in the relevant partial-wave amplitudes provide information on the behaviour of the Δ Regge residue function in the resonance region u>0. Attempts to incorporate this information in parametrizations of the residue by functions that are real on the real u-axis result in residues which have unsatisfactory behaviour in the region u 2 . The choice of complex functions for the trajectory and residue removes this undesirable feature and provides a better representation of the residue in the resonance region, suggesting that complex parametrizations would be better suited to Regge analyses of near-backward scattering. (Auth.)

Parametrization of the. delta. residue function. [Complex functions

Energy Technology Data Exchange (ETDEWEB)

Vasan, S S [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Physics

1976-04-19

The complex residues at the ..delta..(1236) and ..delta..(1950) poles in the relevant partial-wave amplitudes provide information on the behaviour of the ..delta.. Regge residue function in the resonance region u>0. Attempts to incorporate this information in parametrizations of the residue by functions that are real on the real u-axis result in residues which have unsatisfactory behaviour in the region u<1GeV/sup 2/. The choice of complex functions for the trajectory and residue removes this undesirable feature and provides a better representation of the residue in the resonance region, suggesting that complex parametrizations would be better suited to Regge analyses of near-backward scattering.

Parametric biomedical imaging - what defines the quality of quantitative radiological approaches?

International Nuclear Information System (INIS)

Glueer, C.C.; Barkmann, R.; Bolte, H.; Heller, M.; Hahn, H.K.; Dicken, V.; Majumdar, S.; Eckstein, F.; Nickelsen, T.N.

2006-01-01

Quantitative parametric imaging approaches provide new perspectives for radiological imaging. These include quantitative 2D, 3D, and 4D visualization options along with the parametric depiction of biological tissue properties and tissue function. This allows the interpretation of radiological data from a biochemical, biomechanical, or physiological perspective. Quantification permits the detection of small changes that are not yet visually apparent, thus allowing application in early disease diagnosis and monitoring therapy with enhanced sensitivity. This review outlines the potential of quantitative parametric imaging methods and demonstrates this on the basis of a few exemplary applications. One field of particular interest, the use of these methods for investigational new drug application studies, is presented. Assessment criteria for judging the quality of quantitative imaging approaches are discussed in the context of the potential and the limitations of these methods. While quantitative parametric imaging methods do not replace but rather supplement established visual interpretation methods in radiology, they do open up new perspectives for diagnosis and prognosis and in particular for monitoring disease progression and therapy. (orig.)

Parametric structural modeling of insect wings

International Nuclear Information System (INIS)

Mengesha, T E; Vallance, R R; Barraja, M; Mittal, R

2009-01-01

Insects produce thrust and lift forces via coupled fluid-structure interactions that bend and twist their compliant wings during flapping cycles. Insight into this fluid-structure interaction is achieved with numerical modeling techniques such as coupled finite element analysis and computational fluid dynamics, but these methods require accurate and validated structural models of insect wings. Structural models of insect wings depend principally on the shape, dimensions and material properties of the veins and membrane cells. This paper describes a method for parametric modeling of wing geometry using digital images and demonstrates the use of the geometric models in constructing three-dimensional finite element (FE) models and simple reduced-order models. The FE models are more complete and accurate than previously reported models since they accurately represent the topology of the vein network, as well as the shape and dimensions of the veins and membrane cells. The methods are demonstrated by developing a parametric structural model of a cicada forewing.

Network of time-multiplexed optical parametric oscillators as a coherent Ising machine

Science.gov (United States)

Marandi, Alireza; Wang, Zhe; Takata, Kenta; Byer, Robert L.; Yamamoto, Yoshihisa

2014-12-01

Finding the ground states of the Ising Hamiltonian maps to various combinatorial optimization problems in biology, medicine, wireless communications, artificial intelligence and social network. So far, no efficient classical and quantum algorithm is known for these problems and intensive research is focused on creating physical systems—Ising machines—capable of finding the absolute or approximate ground states of the Ising Hamiltonian. Here, we report an Ising machine using a network of degenerate optical parametric oscillators (OPOs). Spins are represented with above-threshold binary phases of the OPOs and the Ising couplings are realized by mutual injections. The network is implemented in a single OPO ring cavity with multiple trains of femtosecond pulses and configurable mutual couplings, and operates at room temperature. We programmed a small non-deterministic polynomial time-hard problem on a 4-OPO Ising machine and in 1,000 runs no computational error was detected.

Woods-Saxon potential parametrization at large deformations for plutonium odd isotopes

International Nuclear Information System (INIS)

Garcia, F.; Garrote, E.; Yoneama, M.L.; Arruda-Neto, J.D.T.; Mesa, J.; Bringas, F.; Likhachev, V.P.; Rodriguez, O.; Guzman, F.

1999-01-01

The structure of single-particle levels in the second minima of 237,239,241 Pu was analyzed with the help of an axially-deformed Woods-Saxon potential. The nuclear shape was parametrized in terms of the cassinian ovaloids. A parametrization of the spin-orbit part of the potential was obtained in the region corresponding to large deformations (second minimum), depending only on the nuclear surface area. With this parametrization, we were able to reproduce successfully the spin, parity and energies of the rotational band built on the 8 μ s isomeric state in 239 Pu and, also, a spin assignment for both isomeric states in 237 Pu and 241 Pu was carried out. (orig.)

Parametric Imaging Of Digital Subtraction Angiography Studies For Renal Transplant Evaluation

Science.gov (United States)

Gallagher, Joe H.; Meaney, Thomas F.; Flechner, Stuart M.; Novick, Andrew C.; Buonocore, Edward

1981-11-01

A noninvasive method for diagnosing acute tubular necrosis and rejection would be an important tool for the management of renal transplant patients. From a sequence of digital subtraction angiographic images acquired after an intravenous injection of radiographic contrast material, the parametric images of the maximum contrast, the time when the maximum contrast is reached, and two times the time at which one half of the maximum contrast is reached are computed. The parametric images of the time when the maximum is reached clearly distinguish normal from abnormal renal function. However, it is the parametric image of two times the time when one half of the maximum is reached which provides some assistance in differentiating acute tubular necrosis from rejection.

A probabilistic strategy for parametric catastrophe insurance

Science.gov (United States)

Figueiredo, Rui; Martina, Mario; Stephenson, David; Youngman, Benjamin

2017-04-01

Economic losses due to natural hazards have shown an upward trend since 1980, which is expected to continue. Recent years have seen a growing worldwide commitment towards the reduction of disaster losses. This requires effective management of disaster risk at all levels, a part of which involves reducing financial vulnerability to disasters ex-ante, ensuring that necessary resources will be available following such events. One way to achieve this is through risk transfer instruments. These can be based on different types of triggers, which determine the conditions under which payouts are made after an event. This study focuses on parametric triggers, where payouts are determined by the occurrence of an event exceeding specified physical parameters at a given location, or at multiple locations, or over a region. This type of product offers a number of important advantages, and its adoption is increasing. The main drawback of parametric triggers is their susceptibility to basis risk, which arises when there is a mismatch between triggered payouts and the occurrence of loss events. This is unavoidable in said programmes, as their calibration is based on models containing a number of different sources of uncertainty. Thus, a deterministic definition of the loss event triggering parameters appears flawed. However, often for simplicity, this is the way in which most parametric models tend to be developed. This study therefore presents an innovative probabilistic strategy for parametric catastrophe insurance. It is advantageous as it recognizes uncertainties and minimizes basis risk while maintaining a simple and transparent procedure. A logistic regression model is constructed here to represent the occurrence of loss events based on certain loss index variables, obtained through the transformation of input environmental variables. Flood-related losses due to rainfall are studied. The resulting model is able, for any given day, to issue probabilities of occurrence of loss

Finite Sample Comparison of Parametric, Semiparametric, and Wavelet Estimators of Fractional Integration

DEFF Research Database (Denmark)

Nielsen, Morten Ø.; Frederiksen, Per Houmann

2005-01-01

In this paper we compare through Monte Carlo simulations the finite sample properties of estimators of the fractional differencing parameter, d. This involves frequency domain, time domain, and wavelet based approaches, and we consider both parametric and semiparametric estimation methods. The es...... the time domain parametric methods, and (4) without sufficient trimming of scales the wavelet-based estimators are heavily biased.......In this paper we compare through Monte Carlo simulations the finite sample properties of estimators of the fractional differencing parameter, d. This involves frequency domain, time domain, and wavelet based approaches, and we consider both parametric and semiparametric estimation methods....... The estimators are briefly introduced and compared, and the criteria adopted for measuring finite sample performance are bias and root mean squared error. Most importantly, the simulations reveal that (1) the frequency domain maximum likelihood procedure is superior to the time domain parametric methods, (2) all...

A parametric study of adverse pressure gradient turbulent boundary layers

International Nuclear Information System (INIS)

Monty, J.P.; Harun, Z.; Marusic, I.

2011-01-01

There are many open questions regarding the behaviour of turbulent boundary layers subjected to pressure gradients and this is confounded by the large parameter space that may affect these flows. While there have been many valuable investigations conducted within this parameter space, there are still insufficient data to attempt to reduce this parameter space. Here, we consider a parametric study of adverse pressure gradient turbulent boundary layers where we restrict our attention to the pressure gradient parameter, β, the Reynolds number and the acceleration parameter, K. The statistics analyzed are limited to the streamwise fluctuating velocity. The data show that the mean velocity profile in strong pressure gradient boundary layers does not conform to the classical logarithmic law. Moreover, there appears to be no measurable logarithmic region in these cases. It is also found that the large-scale motions scaling with outer variables are energised by the pressure gradient. These increasingly strong large-scale motions are found to be the dominant contributor to the increase in turbulence intensity (scaled with friction velocity) with increasing pressure gradient across the boundary layer.

Investigation on phase noise of the signal from a singly resonant optical parametric oscillator

Science.gov (United States)

Jinxia, Feng; Yuanji, Li; Kuanshou, Zhang

2018-04-01

The phase noise of the signal from a singly resonant optical parametric oscillator (SRO) is investigated theoretically and experimentally. An SRO based on periodically poled lithium niobate is built up that generates the signal with a maximum power of 5.2 W at 1.5 µm. The intensity noise of the signal reaches the shot noise level for frequencies above 5 MHz. The phase noise of the signal oscillates depending on the analysis frequency, and there are phase noise peaks above the shot noise level at the peak frequencies. To explain the phase noise feature of the signal, a semi-classical theoretical model of SROs including the guided acoustic wave Brillouin scattering effect within the nonlinear crystal is developed. The theoretical predictions are in good agreement with the experimental results.

Fiber Optical Parametric Chirped Pulse Amplification of Sub-Picosecond Pulses

DEFF Research Database (Denmark)

Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Da Ros, Francesco

2013-01-01

We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs.......We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs....

Strategies for the control of parametric instability in advanced gravitational wave detectors

International Nuclear Information System (INIS)

Ju, L; Blair, D G; Zhao, C; Gras, S; Zhang, Z; Barriga, P; Miao, H; Fan, Y; Merrill, L

2009-01-01

Parametric instabilities have been predicted to occur in all advanced high optical power gravitational wave detectors. In this paper we review the problem of parametric instabilities, summarize the latest findings and assess various schemes proposed for their control. We show that non-resonant passive damping of test masses reduces parametric instability but has a noise penalty, and fails to suppress the Q-factor of many modes. Resonant passive damping is shown to have significant advantages but requires detailed modeling. An optical feedback mode suppression interferometer is proposed which is capable of suppressing all instabilities but requires experimental development.

Strategies for the control of parametric instability in advanced gravitational wave detectors

Energy Technology Data Exchange (ETDEWEB)

Ju, L; Blair, D G; Zhao, C; Gras, S; Zhang, Z; Barriga, P; Miao, H; Fan, Y; Merrill, L, E-mail: juli@physics.uwa.edu.a [School of Physics, University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009 (Australia)

2009-01-07

Parametric instabilities have been predicted to occur in all advanced high optical power gravitational wave detectors. In this paper we review the problem of parametric instabilities, summarize the latest findings and assess various schemes proposed for their control. We show that non-resonant passive damping of test masses reduces parametric instability but has a noise penalty, and fails to suppress the Q-factor of many modes. Resonant passive damping is shown to have significant advantages but requires detailed modeling. An optical feedback mode suppression interferometer is proposed which is capable of suppressing all instabilities but requires experimental development.

Parametric decay of the curvaton

International Nuclear Information System (INIS)

Enqvist, K; Nurmi, S; Rigopoulos, G I

2008-01-01

We argue that the curvaton decay takes place most naturally by way of a broad parametric resonance. The mechanism is analogous to resonant inflaton decay but does not require any tuning of the curvaton coupling strength to other scalar fields. For low scale inflation and a correspondingly low mass scale for the curvaton, we speculate on observable consequences including the possibility of stochastic gravitational waves

The effect of a laser beam displacement on parametric oscillatory instabilities for Advanced LIGO

International Nuclear Information System (INIS)

Heinert, D.; Strigin, S.E.

2011-01-01

The arm cavities of real gravitational wave detectors can show small deviations like a tilt or a spatial shift between the cavity mirrors. These deviations lead to a separation of the optical mode centres with respect to the mirror's centre. In this Letter we perform the computation of parametric instable modes considering the described displacement. We further analyse the possibility of parametric oscillatory instability in the Advanced LIGO interferometer for the case of a displaced arm cavity. Our results reveal an additional number of optical and elastic mode combinations due to a displacement that can give rise to the undesirable effect of parametric oscillatory instability. -- Highlights: → We analyse the possibility of parametric oscillatory instability in the Advanced LIGO interferometer. → We perform the computation of parametric instable modes considering the mirror displacement. → Our results reveal an additional number of optical and elastic mode unstable combinations.

Four-wave mixing and parametric four-wave mixing near the 4P-4S transition of the potassium atom

International Nuclear Information System (INIS)

Katharakis, M; Merlemis, N; Serafetinides, A; Efthimiopoulos, T

2002-01-01

Potassium 4S 1/2 -6S 1/2 two-photon excitation initiates the emission of several internally generated photons. For the first time two emission lines, one close to and one below the potassium 4P 3/2 level, are reported for low pumping intensity. Radiation emitted below the 4P 3/2 level is due to a parametric four-wave mixing process that uses the photons emitted at the 5P 3/2 -4S 1/2 transition and a two-step four-wave mixing process generates the line emitted close to the 4P 3/2 level

Semi-parametrical NAA method for paper analysis

International Nuclear Information System (INIS)

Medeiros, Ilca M.M.A.; Zamboni, Cibele B.; Cruz, Manuel T.F. da; Morel, Jose C.O.; Park, Song W.

2007-01-01

The semi-parametric Neutron Activation Analysis technique, using Au as flux monitor, was applied to determine element concentrations in white paper, usually commercialized, aiming to check the quality control of its production in industrial process. (author)

Optimal parametric modelling of measured short waves

Digital Repository Service at National Institute of Oceanography (India)

Mandal, S.

the importance of selecting a suitable sampling interval for better estimates of parametric modelling and also for better statistical representation. Implementation of the above algorithms in a structural monitoring system has the potential advantage of storing...

Functional form diagnostics for Cox's proportional hazards model.

Science.gov (United States)

León, Larry F; Tsai, Chih-Ling

2004-03-01

We propose a new type of residual and an easily computed functional form test for the Cox proportional hazards model. The proposed test is a modification of the omnibus test for testing the overall fit of a parametric regression model, developed by Stute, González Manteiga, and Presedo Quindimil (1998, Journal of the American Statistical Association93, 141-149), and is based on what we call censoring consistent residuals. In addition, we develop residual plots that can be used to identify the correct functional forms of covariates. We compare our test with the functional form test of Lin, Wei, and Ying (1993, Biometrika80, 557-572) in a simulation study. The practical application of the proposed residuals and functional form test is illustrated using both a simulated data set and a real data set.

Parametrizing coarse grained models for molecular systems at equilibrium

KAUST Repository

Kalligiannaki, Evangelia; Chazirakis, A.; Tsourtis, A.; Katsoulakis, M. A.; Plechá č, P.; Harmandaris, V.

2016-01-01

Hierarchical coarse graining of atomistic molecular systems at equilibrium has been an intensive research topic over the last few decades. In this work we (a) review theoretical and numerical aspects of different parametrization methods (structural-based, force matching and relative entropy) to derive the effective interaction potential between coarse-grained particles. All methods approximate the many body potential of mean force; resulting, however, in different optimization problems. (b) We also use a reformulation of the force matching method by introducing a generalized force matching condition for the local mean force in the sense that allows the approximation of the potential of mean force under both linear and non-linear coarse graining mappings (E. Kalligiannaki, et al., J. Chem. Phys. 2015). We apply and compare these methods to: (a) a benchmark system of two isolated methane molecules; (b) methane liquid; (c) water; and (d) an alkane fluid. Differences between the effective interactions, derived from the various methods, are found that depend on the actual system under study. The results further reveal the relation of the various methods and the sensitivities that may arise in the implementation of numerical methods used in each case.

Parametrizing coarse grained models for molecular systems at equilibrium

KAUST Repository

Kalligiannaki, Evangelia

2016-10-18

Hierarchical coarse graining of atomistic molecular systems at equilibrium has been an intensive research topic over the last few decades. In this work we (a) review theoretical and numerical aspects of different parametrization methods (structural-based, force matching and relative entropy) to derive the effective interaction potential between coarse-grained particles. All methods approximate the many body potential of mean force; resulting, however, in different optimization problems. (b) We also use a reformulation of the force matching method by introducing a generalized force matching condition for the local mean force in the sense that allows the approximation of the potential of mean force under both linear and non-linear coarse graining mappings (E. Kalligiannaki, et al., J. Chem. Phys. 2015). We apply and compare these methods to: (a) a benchmark system of two isolated methane molecules; (b) methane liquid; (c) water; and (d) an alkane fluid. Differences between the effective interactions, derived from the various methods, are found that depend on the actual system under study. The results further reveal the relation of the various methods and the sensitivities that may arise in the implementation of numerical methods used in each case.

Parametric scaling from species to growth-form diversity: an interesting analogy with multifractal functions.

Science.gov (United States)

Ricotta, Carlo; Pacini, Alessandra; Avena, Giancarlo

2002-01-01

We propose a measure of divergence from species to life-form diversity aimed at summarizing the ecological similarity among different plant communities without losing information on traditional taxonomic diversity. First, species and life-form relative abundances within a given plant community are determined. Next, using Rényi's generalized entropy, the diversity profiles of the analyzed community are computed both from species and life-form relative abundances. Finally, the speed of decrease from species to life-form diversity is obtained by combining the outcome of both profiles. Interestingly, the proposed measure shows some formal analogies with multifractal functions developed in statistical physics for the analysis of spatial patterns. As an application for demonstration, a small data set from a plant community sampled in the archaeological site of Paestum (southern Italy) is used.

Consequences of hadron-nucleus multiplicity parametrization

International Nuclear Information System (INIS)

Singh, C.P.; Shyam, M.

1986-01-01

Some interesting consequences are analyzed of a new parametrization for the hadron-nucleus multiplicity distributions and they are compared with the experimental data. Further, it is illustrated how the scaling property for the average multiplicity will be modified and it is found that the experimental data support this behaviour. (orig.)

Parametric resonance in neutrino oscillations in matter

Indian Academy of Sciences (India)

specific phase relationships has an interesting property that it can accumulate if the matter .... In Д 3 we discuss the physical interpretation of the parametric reso- nance in neutrino ..... long-baseline accelerator and reactor experiments [12,29].

Explicit free parametrization of the modified tetrahedron equation

CERN Document Server

Gehlen, G V; Sergeev, S

2003-01-01

The modified tetrahedron equation (MTE) with affine Weyl quantum variables at the Nth root of unity is solved by a rational mapping operator which is obtained from the solution of a linear problem. We show that the solutions can be parametrized in terms of eight free parameters and 16 discrete phase choices, thus providing a broad starting point for the construction of three-dimensional integrable lattice models. The Fermat-curve points parametrizing the representation of the mapping operator in terms of cyclic functions are expressed in terms of the independent parameters. An explicit formula for the density factor of the MTE is derived. For the example N=2 we write the MTE in full detail.

Explicit free parametrization of the modified tetrahedron equation

International Nuclear Information System (INIS)

Gehlen, G von; Pakuliak, S; Sergeev, S

2003-01-01

The modified tetrahedron equation (MTE) with affine Weyl quantum variables at the Nth root of unity is solved by a rational mapping operator which is obtained from the solution of a linear problem. We show that the solutions can be parametrized in terms of eight free parameters and 16 discrete phase choices, thus providing a broad starting point for the construction of three-dimensional integrable lattice models. The Fermat-curve points parametrizing the representation of the mapping operator in terms of cyclic functions are expressed in terms of the independent parameters. An explicit formula for the density factor of the MTE is derived. For the example N=2 we write the MTE in full detail

The evalution of reproduction parametres in chosen herd of sheep

OpenAIRE

BENEŠOVÁ, Kristýna

2009-01-01

It has been observed the breed herd of Texel sheep in the foothills area of Orlické mountains in the year 2005-2008. The base of herd was consisted of 374 ewes, 575 lambs and 6 rams in total. These parametres of reproduction - conception, fertility, rearing, empty ewes, abortions, lambing, stillborn, death after born, were monitored at ewes. For the parametres of reproduction at ewes were found significant effects of ewe´s age and ram´s line.

Fractal Shapes Description with Parametric L-systems and Turtle Algebra

OpenAIRE

Ikbal Zammouri; Béchir Ayeb

2007-01-01

In this paper, we propose a new method to describe fractal shapes using parametric l-systems. First we introduce scaling factors in the production rules of the parametric l-systems grammars. Then we decorticate these grammars with scaling factors using turtle algebra to show the mathematical relation between l-systems and iterated function systems (IFS). We demonstrate that with specific values of the scaling factors, we find the exact relationship established by Prusinkiewicz and Hammel betw...

Parametric Hidden Markov Models for Recognition and Synthesis of Movements

DEFF Research Database (Denmark)

Herzog, Dennis; Krüger, Volker; Grest, Daniel

2008-01-01

In humanoid robotics, the recognition and synthesis of parametric movements plays an extraordinary role for robot human interaction. Such a parametric movement is a movement of a particular type (semantic), for example, similar pointing movements performed at different table-top positions....... For understanding the whole meaning of a movement of a human, the recognition of its type, likewise its parameterization are important. Only both together convey the whole meaning. Vice versa, for mimicry, the synthesis of movements for the motor control of a robot needs to be parameterized, e.g., by the relative...... the applicability for online recognition based on very noisy 3D tracking data. The use of a parametric representation of movements is shown in a robot demo, where a robot removes objects from a table as demonstrated by an advisor. The synthesis for motor control is performed for arbitrary table-top positions....

The LMDZ4 general circulation model: climate performance and sensitivity to parametrized physics with emphasis on tropical convection

Energy Technology Data Exchange (ETDEWEB)

Hourdin, Frederic; Musat, Ionela; Bony, Sandrine; Codron, Francis; Dufresne, Jean-Louis; Fairhead, Laurent; Grandpeix, Jean-Yves; LeVan, Phu; Li, Zhao-Xin; Lott, Francois [CNRS/UPMC, Laboratoire de Meteorologie Dynamique (LMD/IPSL), Paris Cedex 05 (France); Braconnot, Pascale; Friedlingstein, Pierre [Laboratoire des Sciences du Climat et de l' Environnement (LSCE/IPSL), Saclay (France); Filiberti, Marie-Angele [Institut Pierre Simon Laplace (IPSL), Paris (France); Krinner, Gerhard [Laboratoire de Glaciologie et Geophysique de l' Environnement, Grenoble (France)

2006-12-15

The LMDZ4 general circulation model is the atmospheric component of the IPSL-CM4 coupled model which has been used to perform climate change simulations for the 4th IPCC assessment report. The main aspects of the model climatology (forced by observed sea surface temperature) are documented here, as well as the major improvements with respect to the previous versions, which mainly come form the parametrization of tropical convection. A methodology is proposed to help analyse the sensitivity of the tropical Hadley-Walker circulation to the parametrization of cumulus convection and clouds. The tropical circulation is characterized using scalar potentials associated with the horizontal wind and horizontal transport of geopotential (the Laplacian of which is proportional to the total vertical momentum in the atmospheric column). The effect of parametrized physics is analysed in a regime sorted framework using the vertical velocity at 500 hPa as a proxy for large scale vertical motion. Compared to Tiedtke's convection scheme, used in previous versions, the Emanuel's scheme improves the representation of the Hadley-Walker circulation, with a relatively stronger and deeper large scale vertical ascent over tropical continents, and suppresses the marked patterns of concentrated rainfall over oceans. Thanks to the regime sorted analyses, these differences are attributed to intrinsic differences in the vertical distribution of convective heating, and to the lack of self-inhibition by precipitating downdraughts in Tiedtke's parametrization. Both the convection and cloud schemes are shown to control the relative importance of large scale convection over land and ocean, an important point for the behaviour of the coupled model. (orig.)

Bim and Gis: when Parametric Modeling Meets Geospatial Data

Science.gov (United States)

Barazzetti, L.; Banfi, F.

2017-12-01

Geospatial data have a crucial role in several projects related to infrastructures and land management. GIS software are able to perform advanced geospatial analyses, but they lack several instruments and tools for parametric modelling typically available in BIM. At the same time, BIM software designed for buildings have limited tools to handle geospatial data. As things stand at the moment, BIM and GIS could appear as complementary solutions, notwithstanding research work is currently under development to ensure a better level of interoperability, especially at the scale of the building. On the other hand, the transition from the local (building) scale to the infrastructure (where geospatial data cannot be neglected) has already demonstrated that parametric modelling integrated with geoinformation is a powerful tool to simplify and speed up some phases of the design workflow. This paper reviews such mixed approaches with both simulated and real examples, demonstrating that integration is already a reality at specific scales, which are not dominated by "pure" GIS or BIM. The paper will also demonstrate that some traditional operations carried out with GIS software are also available in parametric modelling software for BIM, such as transformation between reference systems, DEM generation, feature extraction, and geospatial queries. A real case study is illustrated and discussed to show the advantage of a combined use of both technologies. BIM and GIS integration can generate greater usage of geospatial data in the AECOO (Architecture, Engineering, Construction, Owner and Operator) industry, as well as new solutions for parametric modelling with additional geoinformation.

BIM AND GIS: WHEN PARAMETRIC MODELING MEETS GEOSPATIAL DATA

Directory of Open Access Journals (Sweden)

L. Barazzetti

2017-12-01

Full Text Available Geospatial data have a crucial role in several projects related to infrastructures and land management. GIS software are able to perform advanced geospatial analyses, but they lack several instruments and tools for parametric modelling typically available in BIM. At the same time, BIM software designed for buildings have limited tools to handle geospatial data. As things stand at the moment, BIM and GIS could appear as complementary solutions, notwithstanding research work is currently under development to ensure a better level of interoperability, especially at the scale of the building. On the other hand, the transition from the local (building scale to the infrastructure (where geospatial data cannot be neglected has already demonstrated that parametric modelling integrated with geoinformation is a powerful tool to simplify and speed up some phases of the design workflow. This paper reviews such mixed approaches with both simulated and real examples, demonstrating that integration is already a reality at specific scales, which are not dominated by “pure” GIS or BIM. The paper will also demonstrate that some traditional operations carried out with GIS software are also available in parametric modelling software for BIM, such as transformation between reference systems, DEM generation, feature extraction, and geospatial queries. A real case study is illustrated and discussed to show the advantage of a combined use of both technologies. BIM and GIS integration can generate greater usage of geospatial data in the AECOO (Architecture, Engineering, Construction, Owner and Operator industry, as well as new solutions for parametric modelling with additional geoinformation.

Parametric decay below the upper hybrid frequency

Energy Technology Data Exchange (ETDEWEB)

Albers, E; Krause, K; Schlueter, H [Bochum Univ. (Germany, F.R.). Inst. fuer Experimentalphysik 2

1977-03-21

Parametric decay of the upper hybrid mode is observed between the electron cyclotron frequency and its first two harmonics. The decay products are identified as electron Bernstein and ion acoustic mode. The diagnostic results confirm the relevant dispersion relations.

Parametric optimization of inverse trapezoid oleophobic surfaces

DEFF Research Database (Denmark)

Cavalli, Andrea; Bøggild, Peter; Okkels, Fridolin

2012-01-01

In this paper, we introduce a comprehensive and versatile approach to the parametric shape optimization of oleophobic surfaces. We evaluate the performance of inverse trapezoid microstructures in terms of three objective parameters: apparent contact angle, maximum sustainable hydrostatic pressure...

Analysis of family-wise error rates in statistical parametric mapping using random field theory.

Science.gov (United States)

Flandin, Guillaume; Friston, Karl J

2017-11-01

This technical report revisits the analysis of family-wise error rates in statistical parametric mapping-using random field theory-reported in (Eklund et al. []: arXiv 1511.01863). Contrary to the understandable spin that these sorts of analyses attract, a review of their results suggests that they endorse the use of parametric assumptions-and random field theory-in the analysis of functional neuroimaging data. We briefly rehearse the advantages parametric analyses offer over nonparametric alternatives and then unpack the implications of (Eklund et al. []: arXiv 1511.01863) for parametric procedures. Hum Brain Mapp, 2017. © 2017 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. © 2017 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Influence of Variable Acceleration on Parametric Roll Motion of a Container Ship

Directory of Open Access Journals (Sweden)

Emre PEŞMAN

2016-09-01

Full Text Available Ship operators increase or decrease thrust force of ships to avoid parametric roll motion. These operations cause varying acceleration values. In this study, influence of variable acceleration and deceleration of ships on roll motion is investigated in longitudinal waves. The method which is referred as simple model is utilized for analysis. Simple Model is one degree of freedom nonlinear parametric roll motion equation which contains changing velocity and restoring moment in waves with respect to time. Ship velocities in waves are predicted by XFlow software for various thrust forces. Results indicate that variable acceleration has significant effect on parametric roll phenomenon.

Evaluation of linear ozone photochemistry parametrizations in a stratosphere-troposphere data assimilation system

Directory of Open Access Journals (Sweden)

A. J. Geer

2007-01-01

Full Text Available This paper evaluates the performance of various linear ozone photochemistry parametrizations using the stratosphere-troposphere data assimilation system of the Met Office. A set of experiments were run for the period 23 September 2003 to 5 November 2003 using the Cariolle (v1.0 and v2.1, LINOZ and Chem2D-OPP (v0.1 and v2.1 parametrizations. All operational meteorological observations were assimilated, together with ozone retrievals from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS. Experiments were validated against independent data from the Halogen Occultation Experiment (HALOE and ozonesondes. Additionally, a simple offline method for comparing the parametrizations is introduced. It is shown that in the upper stratosphere and mesosphere, outside the polar night, ozone analyses are controlled by the photochemistry parametrizations and not by the assimilated observations. The most important factor in getting good results at these levels is to pay attention to the ozone and temperature climatologies in the parametrizations. There should be no discrepancies between the climatologies and the assimilated observations or the model, but there is also a competing demand that the climatologies be objectively accurate in themselves. Conversely, in the lower stratosphere outside regions of heterogeneous ozone depletion, the ozone analyses are dominated by observational increments and the photochemistry parametrizations have little influence. We investigate a number of known problems in LINOZ and Cariolle v1.0 in more detail than previously, and we find discrepancies in Cariolle v2.1 and Chem2D-OPP v2.1, which are demonstrated to have been removed in the latest available versions (v2.8 and v2.6 respectively. In general, however, all the parametrizations work well through much of the stratosphere, helped by the presence of good quality assimilated MIPAS observations.

Monitoring coastal marshes biomass with CASI: a comparison of parametric and non-parametric models

Science.gov (United States)

Mo, Y.; Kearney, M.

2017-12-01

Coastal marshes are important carbon sinks that face multiple natural and anthropogenic stresses. Optical remote sensing is a powerful tool for closely monitoring the biomass of coastal marshes. However, application of hyperspectral sensors on assessing the biomass of diverse coastal marsh ecosystems is limited. This study samples spectral and biophysical data from coastal freshwater, intermediate, brackish, and saline marshes in Louisiana, and develops parametric and non-parametric models for using the Compact Airborne Spectrographic Imager (CASI) to retrieve the marshes' biomass. Linear models and random forest models are developed from simulated CASI data (48 bands, 380-1050 nm, bandwidth 14 nm). Linear models are also developed using narrowband vegetation indices computed from all possible band combinations from the blue, red, and near infrared wavelengths. It is found that the linear models derived from the optimal narrowband vegetation indices provide strong predictions for the marshes' Leaf Area Index (LAI; R2 > 0.74 for ARVI), but not for their Aboveground Green Biomass (AGB; R2 > 0.25). The linear models derived from the simulated CASI data strongly predict the marshes' LAI (R2 = 0.93) and AGB (R2 = 0.71) and have 27 and 30 bands/variables in the final models through stepwise regression, respectively. The random forest models derived from the simulated CASI data also strongly predict the marshes' LAI and AGB (R2 = 0.91 and 0.84, respectively), where the most important variables for predicting LAI are near infrared bands at 784 and 756 nm and for predicting ABG are red bands at 684 and 670 nm. In sum, the random forest model is preferable for assessing coastal marsh biomass using CASI data as it offers high R2 for both LAI and AGB. The superior performance of the random forest model is likely to due to that it fully utilizes the full-spectrum data and makes no assumption of the approximate normality of the sampling population. This study offers solutions

Experimental investigation of the interaction of an intense laser beam with a long and hot plasma in the context of shock ignition

International Nuclear Information System (INIS)

Goyon, Clement

2014-01-01

Shock ignition is an alternative direct-drive scheme for inertial fusion that consists in two steps. The first one is a several nanoseconds long compression with low intensity beams. The second one is a several hundred of picoseconds stage using high intensity beams to create a converging shock leading to ignition. During the second phase, the laser beam goes through a long and hot under-critical plasma. However, the coupling of this intense pulse with the coronal plasma has not been much studied experimentally or numerically. Then, the energy absorbed as well as the role of parametric instabilities regarding reflected or transmitted intensity cannot be predicted. In this PhD dissertation, we describe an experimental study of an intense laser pulse between 2.10 15 W/cm 2 and 2.10 16 W/cm 2 interacting with millimetric plasma heated close to one keV. We begin with a theoretical description of the interaction conditions in the coronal plasma. Brillouin scattering is in strongly coupled regime, Raman instability is kinetic regime and laser intensity is above ponderomotive filamentation threshold. We recreate these interaction conditions experimentally by means of pre-heated targets which are foams or thin plastic foils. Then, we present the first measurements of time resolved backscattered spectra from the smoothed picosecond beam as well as transmitted intensity distribution through the plasma. We find that Brillouin instability can be responsible for up to 60% reflectivity in plasmas with electronic density close to critical while Raman reflectivity stays at low levels. Transmitted intensity distribution is smoothed by the propagation and its diameter increases compared to the laser focal spot in vacuum. Finally, we discuss interaction measurements in nanosecond regime to highlight the fact that parametric instabilities reduction is essential for shock ignition to be a successful scheme. (author) [fr

Green-Schwarz superstring: Beltrami parametrization and world-sheet supersymmetric generalization

International Nuclear Information System (INIS)

Binetruy, P.; Girardi, G.; Grimm, R.

1989-06-01

We study a generalization of the superstring theory in which both world-sheet and space-time supersymmetries are explicit. This hybrid superstring interpolates between the Green-Schwarz and the Ramond-Neveu-Schwarz formulations. We show that the Beltrami parametrization of the world-sheet provides a natural setting for the description of K-transformations already in the Green-Schwarz string. We construct the hybrid superstring action using the (1,1) supersymmetric version of the Beltrami parametrization. We discuss the generalization of k-transformations

Synchronously Pumped Optical Parametric Oscillator with Intracavity Difference Frequency Mixing

Science.gov (United States)

1998-06-29

departing from the Rrpubbc of Panama when traveling on official orders." * " De eonfortnidad con el Parrafo 5u) del Articulo XVII del Acuerdo para U...isotopic photochemistry using an optical parametric oscillator and a down converter," J. Opt. ( Paris ), , no. 14, pp. 43-48, 1983. [4] J. D. Kafka, M. L...isotopic photochemistry using an optical parametric oscillator and a down converter," J. Opt. ( Paris ), , no. 14, pp. 43-48, 1983. [4] J. D. Kafka, M. L

Parametric study of prospective early commercial OCMHD power plants /PSPEC/

Science.gov (United States)

Marston, C. H.; Bender, D. J.; Hnat, J. G.; Dellinger, T. C.

1980-06-01

The paper presents a parametric study conducted to obtain the performance, economics, natural resource requirements, and environmental impact of moderate technology MHD/steam power plants that do not require development of direct-fired high-temperature air heaters. The study was divided into three base cases, each with a reference case and parametric variations. The case using recuperative air preheat in the range of 1000 F to 1300 F, combined with O2 enrichment to 42% by volume has been selected for conceptual design.

Measurement of IR optics with linear coupling's action-angle parametrization

Science.gov (United States)

Luo, Y.; Bai, M.; Pilat, F.; Satogata, T.; Trbojevic, D.

2005-08-01

Linear coupling’s action-angle parametrization is convenient for interpretation of turn-by-turn beam position monitor (BPM) data. We demonstrate how to apply this parametrization to extract Twiss and coupling parameters in interaction regions (IRs), using BPMs on each side of a long IR drift region. Example data were acquired at the Relativistic Heavy Ion Collider, using an ac dipole to excite a single transverse eigenmode. We have measured the waist of the β function and its Twiss and coupling parameters.

A new parametric equation of state and quark stars

International Nuclear Information System (INIS)

Na Xuesen; Xu Renxin

2011-01-01

It is still a matter of debate to understand the equation of state of cold matter with supra-nuclear density in compact stars because of unknown non-perturbative strong interaction between quarks. Nevertheless, it is speculated from an astrophysical view point that quark clusters could form in cold quark matter due to strong coupling at realistic baryon densities. Although it is hard to calculate this conjectured matter from first principles, one can expect that the inter-cluster interaction will share some general features with the nucleon- nucleon interaction successfully depicted by various models. We adopt a two-Gaussian component soft-core potential with these general features and show that quark clusters can form stable simple cubic crystal structure if we assume that the wave function of quark clusters have a Gaussian form. With this parametrization, the Tolman-Oppenheimer-Volkoff equation is solved with reasonably constrained parameter space to give mass-radius relations of crystalline solid quark stars. With baryon number densities truncated at 2n 0 at surface and the range of the interaction fixed at 2 fm we can reproduce similar mass-radius relations to that obtained with bag model equations of state. The maximum mass ranges from ∼ 0.5 solar mass to approx.> 3 solar mass . The recently measured high pulsar mass (approx.> 2 solar mass ) is then used to constrain the parameters of this simple interaction potential. (authors)

Prospect theory: A parametric analysis of functional forms in Brazil

Directory of Open Access Journals (Sweden)

Robert Eugene Lobel

2017-10-01

Full Text Available This study aims to analyze risk preferences in Brazil based on prospect theory by estimating the risk aversion parameter of the expected utility theory (EUT for a select sample, in addition to the value and probability function parameter, assuming various functional forms, and a newly proposed value function, the modified log. This is the first such study in Brazil, and the parameter results are slightly different from studies in other countries, indicating that subjects are more risk averse and exhibit a smaller loss aversion. Probability distortion is the only common factor. As expected, the study finds that behavioral models are superior to EUT, and models based on prospect theory, the TK and Prelec weighting function, and the value power function show superior performance to others. Finally, the modified log function proposed in the study fits the data well, and can thus be used for future studies in Brazil.

Intense lower-hybrid wave penetration and current drive in reactor-grade plasmas

International Nuclear Information System (INIS)

Cohen, R.H.; Rognlien, T.D; Bonoli, P.T.; Porkolab, M.

1990-01-01

Apply lower-hybrid power in short, intense pulses can overcome Landau damping, allowing penetration into the core of reactor-grade plasmas. We present a theoretical description of the absorption and parametric stability of the pulses, and show results of ray-tracing calculations which include the absorption calculation. Consideration of the absorption and potential source availability lead to the consideration of 5--10 GW peak power, 30--100 μs pulses for ITER, and ∼ 2 MW, 20 μs pulses for a proof-of-principle experiment in the Microwave Tokamak Experiment (MTX)

Intense lower-hybrid wave penetration and current drive in reactor-grade plasmas

Energy Technology Data Exchange (ETDEWEB)

Cohen, R.H.; Rognlien, T.D (Lawrence Livermore National Lab., CA (USA)); Bonoli, P.T.; Porkolab, M. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Plasma Fusion Center)

1990-01-01

Apply lower-hybrid power in short, intense pulses can overcome Landau damping, allowing penetration into the core of reactor-grade plasmas. We present a theoretical description of the absorption and parametric stability of the pulses, and show results of ray-tracing calculations which include the absorption calculation. Consideration of the absorption and potential source availability lead to the consideration of 5--10 GW peak power, 30--100 {mu}s pulses for ITER, and {approximately} 2 MW, 20 {mu}s pulses for a proof-of-principle experiment in the Microwave Tokamak Experiment (MTX).

Low-Threshold Optical Parametric Oscillations in a Whispering Gallery Mode Resonator

DEFF Research Database (Denmark)

Fürst, J. U.; Strekalov, D. V.; Elser, D.

2010-01-01

In whispering gallery mode (WGM) resonator light is guided by continuous total internal reflection along a curved surface. Fabricating such resonators from an optically nonlinear material one takes advantage of their exceptionally high quality factors and small mode volumes to achieve extremely...... efficient optical frequency conversion. Our analysis of the phase-matching conditions for optical parametric down-conversion (PDC) in a spherical WGM resonator shows their direct relation to the sum rules for photons' angular momenta and predicts a very low parametric oscillation threshold. We realized...... such an optical parametric oscillator (OPO) based on naturally phase-matched PDC in lithium niobate. We demonstrated a single-mode, strongly nondegenerate OPO with a threshold of 6.7  μW and linewidth under 10 MHz. This work demonstrates the remarkable capabilities of WGM-based OPOs....

The role of nonlinear beating currents on parametric instabilities in magnetoplasmas

International Nuclear Information System (INIS)

Kuo, S.P.

1996-01-01

A general coupled mode equation for the low-frequency decay modes of parametric instabilities in magnetoplasmas is derived. The relative importance of the nonlinear contributions from the ponderomotive force, nonlinear beating current, and anisotropic effect to the parametric coupling is then manifested by the coupling terms of the equation. It is first shown in the unmagnetized case, that the contribution of the nonlinear beating current is negligibly small because of the small coefficient (i.e., weight) of this current contribution, instead of the beating current itself. It then follows that the weight of the beating current contribution increases significantly in the magnetized case, and consequently, this contribution to the parametric coupling is found to be important, as exemplified by two specific examples. copyright 1996 American Institute of Physics

Parametric uncertainty in optical image modeling

Science.gov (United States)

Potzick, James; Marx, Egon; Davidson, Mark

2006-10-01

Optical photomask feature metrology and wafer exposure process simulation both rely on optical image modeling for accurate results. While it is fair to question the accuracies of the available models, model results also depend on several input parameters describing the object and imaging system. Errors in these parameter values can lead to significant errors in the modeled image. These parameters include wavelength, illumination and objective NA's, magnification, focus, etc. for the optical system, and topography, complex index of refraction n and k, etc. for the object. In this paper each input parameter is varied over a range about its nominal value and the corresponding images simulated. Second order parameter interactions are not explored. Using the scenario of the optical measurement of photomask features, these parametric sensitivities are quantified by calculating the apparent change of the measured linewidth for a small change in the relevant parameter. Then, using reasonable values for the estimated uncertainties of these parameters, the parametric linewidth uncertainties can be calculated and combined to give a lower limit to the linewidth measurement uncertainty for those parameter uncertainties.

Alternative waste form development - low-temperature pyrolytic carbon coatings

International Nuclear Information System (INIS)

Oma, K.H.; Rusin, J.M.; Kidd, R.W.; Browning, M.F.

1981-01-01

Although several chemical vapor deposition (CVD) - coated waste forms have been successfully produced, some major disadvantages associated with the high-temperature fluidized-bed CVD coating process exist. To overcome these disadvantages, the Pacific Northwest Laboratory has initiated the development of a pyrolytic carbon CVD coating system to coat large waste-form particles at temperatures ranging from 400 to 500/degree/C. This relatively simple system has been used to coat kilogram quantities of simulated waste-glass marbles. Further development of this system could result in a viable process to coat bulk quantities of both glass and ceramic waste forms. This paper discusses various aspects of the development work, including coating techniques, parametric study, and coater equipment. 10 refs

An extended parametrization of gas amplification in proportional wire chambers

International Nuclear Information System (INIS)

Beingessner, S.P.; Carnegie, R.K.; Hargrove, C.K.

1987-01-01

It is normally assumed that the gas amplification in proportional chambers is a function of Townsend's first ionization coefficient, α, and that α is a function of the anode surface electric field only. Experimental measurements are presented demonstrating the breakdown of the latter assumption for electric fields, X, greater than about 150 V/cm/Torr on the anode wire surface for a gas mixture of 80/20 argon/methane. For larger values of X, the parametrization of the proportional gas gain data requires an additional term related to the gradient of the electric field near the wire. This extended gain parametrization remains valid until the onset of nonproportional contributions such as positive ion space charge saturation effects. Furthermore, deviations of the data from this parametrization are used to measure the onset of these space charge effects. A simple scaling dependence of the gain data on the product of pressure and wire radius over the whole proportional range is also demonstrated. (orig.)

Effect of different tillage intensity on yields and yield-forming factors in winter wheat

Directory of Open Access Journals (Sweden)

Martin Houšť

2012-01-01

Full Text Available The paper presents results of a study on application of minimum tillage technologies when growing winter wheat. Experiments were performed in the sugar-beet-growing region with loamy chernozem within the period of 2005–2009. Aanalysed and evaluated were effects of different methods of soil processing on yield-forming factors in stands of winter wheat grown after three different preceding crops (i.e. alfalfa, maize for silage and pea. Evaluated were the following four variants of tillage: (1 conventional ploughing to the depth of 0.22 m (Variant 1; (2 ploughing to the depth of 0.15 m (Variant 2; (3 direct sowing into the untilled soil (Variant 3, and (4 shallow tillage to the depth of 0.10 m (Variant 4.The effect of different tillage intensity on winter wheat yields was statistically non-significant after all forecrops. After alfalfa, the highest and the lowest average yields were recorded in Variant 2 (i.e. with ploughing to the depth of 0.15 m and Variant 3 (direct sowing into the untilled soil, respectively. After maize grown for silage, higher yields were obtained in Variant 2 and Variant 1 (conventional ploughing while in Variants 4 and 3 the obtained yields were lower. When growing winter wheat after pea as a preceding crop, the highest and the lowest average yields were recorded after direct sowing (Variant 3 and in Variant 1 (i.e. ploughing to the depth of 0.22 m, respectively. Results of studies on effect of different tillage technologies on yields of winter wheat crops indicate that under the given pedological and climatic conditions it is possible to apply methods of reduced tillage intensity. However, the choice of the corresponding technology must be performed with regard to the type of preceding crop.

H-mode profile parametrization for extrapolation and control

International Nuclear Information System (INIS)

Imre, K.; Riedel, K.S.; Schissel, D.P.; Schunke, B.

1996-01-01

A steady-state ELMy H-mode profile data set of 68 DIII-D discharges and 74 JET discharges is fitted with an error of 7-8%. The advantages of a parametrization of the plasma profiles in terms of a semi-parametric representation, T(ρ, I p , n-bar, B t , P L , R), are described. The shape of the temperature profile depends almost exclusively upon the size, R and q 95 , with a secondary dependence on the heating power. The density profile depends primarily upon q95 with a secondary dependence on n-bar. The line-average temperature T-bar e scales as n-bar -0.31 instead of T-bar∼''n-bar'' -1.0 . The predicted ITER temperature is T-bar = 17.1 keV. (Author)

Parametric Covariance Model for Horizon-Based Optical Navigation

Science.gov (United States)

Hikes, Jacob; Liounis, Andrew J.; Christian, John A.

2016-01-01

This Note presents an entirely parametric version of the covariance for horizon-based optical navigation measurements. The covariance can be written as a function of only the spacecraft position, two sensor design parameters, the illumination direction, the size of the observed planet, the size of the lit arc to be used, and the total number of observed horizon points. As a result, one may now more clearly understand the sensitivity of horizon-based optical navigation performance as a function of these key design parameters, which is insight that was obscured in previous (and nonparametric) versions of the covariance. Finally, the new parametric covariance is shown to agree with both the nonparametric analytic covariance and results from a Monte Carlo analysis.

Mid-thickness studies of the stress intensity factor in the bulk of bainitic steel

Directory of Open Access Journals (Sweden)

P. Lopez-Crespo

2017-07-01

Full Text Available The current work aims at estimating the stress intensity factor deep inside the bulk from elastic strain data measured by synchrotron X-ray diffraction. Key features affecting the evaluation of the stress intensity factor are the number of terms in the analytical model describing the crack tip field, the extension and position of the area of interest of the experimental data, the effect of the experimental data collected within the plastic zone and the number of elastic strain data points used. Here a parametric study of these features is presented in terms of their influence for the stress intensity factor determination. It was found that 3 or 4 terms in Williams’ expansion is often sufficient; the data should be collected from across the full range of angles around the crack tip; and the number of points/number of terms should be greater than 40.

Non-parametric PSF estimation from celestial transit solar images using blind deconvolution

Directory of Open Access Journals (Sweden)

González Adriana

2016-01-01

Full Text Available Context: Characterization of instrumental effects in astronomical imaging is important in order to extract accurate physical information from the observations. The measured image in a real optical instrument is usually represented by the convolution of an ideal image with a Point Spread Function (PSF. Additionally, the image acquisition process is also contaminated by other sources of noise (read-out, photon-counting. The problem of estimating both the PSF and a denoised image is called blind deconvolution and is ill-posed. Aims: We propose a blind deconvolution scheme that relies on image regularization. Contrarily to most methods presented in the literature, our method does not assume a parametric model of the PSF and can thus be applied to any telescope. Methods: Our scheme uses a wavelet analysis prior model on the image and weak assumptions on the PSF. We use observations from a celestial transit, where the occulting body can be assumed to be a black disk. These constraints allow us to retain meaningful solutions for the filter and the image, eliminating trivial, translated, and interchanged solutions. Under an additive Gaussian noise assumption, they also enforce noise canceling and avoid reconstruction artifacts by promoting the whiteness of the residual between the blurred observations and the cleaned data. Results: Our method is applied to synthetic and experimental data. The PSF is estimated for the SECCHI/EUVI instrument using the 2007 Lunar transit, and for SDO/AIA using the 2012 Venus transit. Results show that the proposed non-parametric blind deconvolution method is able to estimate the core of the PSF with a similar quality to parametric methods proposed in the literature. We also show that, if these parametric estimations are incorporated in the acquisition model, the resulting PSF outperforms both the parametric and non-parametric methods.

Parametric Optimization of Hospital Design

DEFF Research Database (Denmark)

Holst, Malene Kirstine; Kirkegaard, Poul Henning; Christoffersen, L.D.

2013-01-01

Present paper presents a parametric performancebased design model for optimizing hospital design. The design model operates with geometric input parameters defining the functional requirements of the hospital and input parameters in terms of performance objectives defining the design requirements...... and preferences of the hospital with respect to performances. The design model takes point of departure in the hospital functionalities as a set of defined parameters and rules describing the design requirements and preferences....

Revisiting non-degenerate parametric down-conversion

Indian Academy of Sciences (India)

conversion process is studied by recasting the time evolution equations for the basic op- erators in an equivalent ... We consider a model of non-degenerate parametric down-conversion process com- posed of two coupled ..... e−iωat and eiωbt have been left out in writing down the final results in ref. [4], even though these ...

Extended parametric gain range in photonic crystal fibers with strongly frequency-dependent field distributions.

Science.gov (United States)

Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

2014-08-15

The parametric gain range of a degenerate four-wave mixing process is determined in the undepleted pump regime. The gain range is considered with and without taking the mode field distributions of the four-wave mixing components into account. It is found that the mode field distributions have to be included to evaluate the parametric gain correctly in dispersion-tailored speciality fibers and that mode profile engineering can provide a way to increase the parametric gain range.

Optimal Design of Experiments for Parametric Identification of Civil Engineering Structures

OpenAIRE

Kirkegaard, Poul Henning

1991-01-01

Optimal Systems of experiments for parametric identification of civil engineering structures is investigated. Design of experiments for parametric identification of dynamic systems is usually done by minimizing a scalar measure, e.g the determinant, the trace ect., of an estimated parameter covariance matrix, based on prior knowledge. The experimental conditions available for adjustment, considering in this thesis, are input signal, sampling rate, the location of sensors and number of sensors.

Development of suspended core soft glass fibers for far-detuned parametric conversion

Science.gov (United States)

Rampur, Anupamaa; Ciąćka, Piotr; Cimek, Jarosław; Kasztelanic, Rafał; Buczyński, Ryszard; Klimczak, Mariusz

2018-04-01

Light sources utilizing χ (2) parametric conversion combine high brightness with attractive operation wavelengths in the near and mid-infrared. In optical fibers, it is possible to use χ (3) degenerate four-wave mixing in order to obtain signal-to-idler frequency detuning of over 100 THz. We report on a test series of nonlinear soft glass suspended core fibers intended for parametric conversion of 1000-1100 nm signal wavelengths available from an array of mature lasers into the near-to-mid-infrared range of 2700-3500 nm under pumping with an erbium sub-picosecond laser system. The presented discussion includes modelling of the fiber properties, details of their physical development and characterization, and experimental tests of parametric conversion.

Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric Decay

Science.gov (United States)

Bowen, Trevor A.; Badman, Samuel; Hellinger, Petr; Bale, Stuart D.

2018-02-01

Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures, kinetic ion-acoustic waves, as well as the MHD slow-mode. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggestive of a local driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the Alfvén wave parametric instability. Here, we test the parametric decay process as a source of compressive waves in the solar wind by comparing the collisionless damping rates of compressive fluctuations with growth rates of the parametric decay instability daughter waves. Our results suggest that generation of compressive waves through parametric decay is overdamped at 1 au, but that the presence of slow-mode-like density fluctuations is correlated with the parametric decay of Alfvén waves.

Clinical Alarms in intensive care: implications of alarm fatigue for the safety of patients

Directory of Open Access Journals (Sweden)

Adriana Carla Bridi

2014-12-01

Full Text Available OBJECTIVES: to identify the number of electro-medical pieces of equipment in a coronary care unit, characterize their types, and analyze implications for the safety of patients from the perspective of alarm fatigue.METHOD: this quantitative, observational, descriptive, non-participatory study was conducted in a coronary care unit of a cardiology hospital with 170 beds.RESULTS: a total of 426 alarms were recorded in 40 hours of observation: 227 were triggered by multi-parametric monitors and 199 were triggered by other equipment (infusion pumps, dialysis pumps, mechanical ventilators, and intra-aortic balloons; that is an average of 10.6 alarms per hour.CONCLUSION: the results reinforce the importance of properly configuring physiological variables, the volume and parameters of alarms of multi-parametric monitors within the routine of intensive care units. The alarms of equipment intended to protect patients have increased noise within the unit, the level of distraction and interruptions in the workflow, leading to a false sense of security.

Improved parametrization of K+ production in p-Be collisions at low energy using Feynman scaling

International Nuclear Information System (INIS)

Mariani, C.; Cheng, G.; Shaevitz, M. H.; Conrad, J. M.

2011-01-01

This paper describes an improved parametrization for proton-beryllium production of secondary K + mesons for experiments with primary proton beams from 8.89 to 24 GeV/c. The parametrization is based on Feynman scaling in which the invariant cross section is described as a function of x F and p T . This method is theoretically motivated and provides a better description of the energy dependence of kaon production at low beam energies than other parametrizations such as the commonly used modified Sanford-Wang model. This Feynman scaling parametrization has been used for the simulation of the neutrino flux from the Booster Neutrino Beam at Fermilab and has been shown to agree with the neutrino interaction data from the SciBooNE experiment. This parametrization will also be useful for future neutrino experiments with low primary beam energies, such as those planned for the Project X accelerator.

Study of the long-term values and prices of plutonium; a simplified parametrized model; Etude des valeurs et des prix du plutonium a long terme; un modele parametre simplifie

Energy Technology Data Exchange (ETDEWEB)

Gaussens, J; Paillot, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

The authors define the notions of use values and price of plutonium. They give a 'simplified parametrized model' simulating the equilibrium of the offer and the demand in time, concerning the plutonium and the price deriving from the relative scarcity of this metal, taking into account the technical and economic operating parameters of the various reactors confronted. This model is simple enough to allow direct computations and establish clear relations between the various parameters. The use of the linear programmes method allows on the other hand a wide extension of the model. This report includes three main parts: I - General description of the study (without detailed calculations) II - Mathematical development of the simplified parametrized model and application (the basic data and the results of the calculations are given) III - Appendices (giving the detailed computations of part II). (authors) [French] Les auteurs definissent les notions de valeurs d'usage et de prix du plutonium. Ils donnent un 'modele parametre simplifie' simulant l'equilibre de l'office et de la demande dans le temps concernant le plutonium et le prix qui decoule de la rarete relative de ce metal, compte tenu des parametres techniques et economiques de fonctionnement des divers reacteurs en presence. Ce modele est suffisamment simple pour permettre des calculs manuels et etablir des liaisons claires entre les divers parametres. L'utilisation de la technique des programmes lineaires permet par ailleurs une extension considerable du modele. Cette note comprend trois parties: I - Expose general de l'etude (sans expose du detail des calculs) II - Developpement mathematique du modele parametre simplifie et application (on precise les donnees de base et le resultat des calculs) III - Annexes (donnant le detail des calculs de la partie II). (auteurs)

Parametric x-ray FEL operating with external Bragg reflectors

International Nuclear Information System (INIS)

Baryshevsky, V.G.; Batrakov, K.G.; Dubovskaya, I.Ya.

1995-01-01

In the crystal X-ray FELs using channeling and parametric quasi-Cherenkov mechanisms of spontaneous radiation were considered as versions of FEL allowing, in principle, to obtain coherent X-ray source. In this case a crystal is both radiator and resonator for X-rays emitted by a particle beam passing through crystal. However, it is well-known that a beam current density required for lasing is extremely high in X-ray spectral range for any radiation mechanisms and it is very important to find a way to lower its magnitude. The application of three-dimensional distributed feedback formed by dynamical diffraction of emitted photons permitted to reduce starting beam current density 10 2 -10 4 times up to 10 9 . One of ways to lower the starting current is the formation of multi-wave distributed feedback the another one is the application of external reflectors. The thing is that lasing regime was shown to be produced at frequencies in the vicinity of degeneration point for roots of dispersion equation describing radiation modes excited in an active medium (crystal plus particle beam). Unfortunately, in case of parametric quasi-Cherenkov FEL this region coincides with the region of strong self-absorption of radiation inside a crystal. That fact, obviously, increases the starting beam current. In this report we have shown that the application of external Bragg reflectors gives the possibility to lower radiation self-absorption inside a crystal by modifying radiation modes excited in the active medium under consideration. The corresponding dispersion equation and the expression for excited modes are derived. The generation equation determining starting conditions for lasing is obtained. Using these expressions we have shown that the application of external Bragg reflectors permits to reduce starting beam current density more than 10 times

Model Adaptation in Parametric Space for POD-Galerkin Models

Science.gov (United States)

Gao, Haotian; Wei, Mingjun

2017-11-01

The development of low-order POD-Galerkin models is largely motivated by the expectation to use the model developed with a set of parameters at their native values to predict the dynamic behaviors of the same system under different parametric values, in other words, a successful model adaptation in parametric space. However, most of time, even small deviation of parameters from their original value may lead to large deviation or unstable results. It has been shown that adding more information (e.g. a steady state, mean value of a different unsteady state, or an entire different set of POD modes) may improve the prediction of flow with other parametric states. For a simple case of the flow passing a fixed cylinder, an orthogonal mean mode at a different Reynolds number may stabilize the POD-Galerkin model when Reynolds number is changed. For a more complicated case of the flow passing an oscillatory cylinder, a global POD-Galerkin model is first applied to handle the moving boundaries, then more information (e.g. more POD modes) is required to predicate the flow under different oscillatory frequencies. Supported by ARL.

Transition redshift: new constraints from parametric and nonparametric methods

Energy Technology Data Exchange (ETDEWEB)

Rani, Nisha; Mahajan, Shobhit; Mukherjee, Amitabha [Department of Physics and Astrophysics, University of Delhi, New Delhi 110007 (India); Jain, Deepak [Deen Dayal Upadhyaya College, University of Delhi, New Delhi 110015 (India); Pires, Nilza, E-mail: nrani@physics.du.ac.in, E-mail: djain@ddu.du.ac.in, E-mail: shobhit.mahajan@gmail.com, E-mail: amimukh@gmail.com, E-mail: npires@dfte.ufrn.br [Departamento de Física Teórica e Experimental, UFRN, Campus Universitário, Natal, RN 59072-970 (Brazil)

2015-12-01

In this paper, we use the cosmokinematics approach to study the accelerated expansion of the Universe. This is a model independent approach and depends only on the assumption that the Universe is homogeneous and isotropic and is described by the FRW metric. We parametrize the deceleration parameter, q(z), to constrain the transition redshift (z{sub t}) at which the expansion of the Universe goes from a decelerating to an accelerating phase. We use three different parametrizations of q(z) namely, q{sub I}(z)=q{sub 1}+q{sub 2}z, q{sub II} (z) = q{sub 3} + q{sub 4} ln (1 + z) and q{sub III} (z)=½+q{sub 5}/(1+z){sup 2}. A joint analysis of the age of galaxies, strong lensing and supernovae Ia data indicates that the transition redshift is less than unity i.e. z{sub t} < 1. We also use a nonparametric approach (LOESS+SIMEX) to constrain z{sub t}. This too gives z{sub t} < 1 which is consistent with the value obtained by the parametric approach.

Efficient Characterization of Parametric Uncertainty of Complex (Biochemical Networks.

Directory of Open Access Journals (Sweden)

Claudia Schillings

2015-08-01

Full Text Available Parametric uncertainty is a particularly challenging and relevant aspect of systems analysis in domains such as systems biology where, both for inference and for assessing prediction uncertainties, it is essential to characterize the system behavior globally in the parameter space. However, current methods based on local approximations or on Monte-Carlo sampling cope only insufficiently with high-dimensional parameter spaces associated with complex network models. Here, we propose an alternative deterministic methodology that relies on sparse polynomial approximations. We propose a deterministic computational interpolation scheme which identifies most significant expansion coefficients adaptively. We present its performance in kinetic model equations from computational systems biology with several hundred parameters and state variables, leading to numerical approximations of the parametric solution on the entire parameter space. The scheme is based on adaptive Smolyak interpolation of the parametric solution at judiciously and adaptively chosen points in parameter space. As Monte-Carlo sampling, it is "non-intrusive" and well-suited for massively parallel implementation, but affords higher convergence rates. This opens up new avenues for large-scale dynamic network analysis by enabling scaling for many applications, including parameter estimation, uncertainty quantification, and systems design.

The RECENT code with the Reich-Moore parametrization

International Nuclear Information System (INIS)

Melnikoff, M.; Chalhoub, E.S.; Carlson, B.V.

1985-01-01

The program RECENT, which reconstructs neutron cross sections from resonance parameters given in the ENDF/B format, was modified in order to include in its structure the Reich-Moore parametrization. (Author) [pt

TMsim: An Algorithmic Tool for the Parametric and Worst-Case Simulation of Systems with Uncertainties

Directory of Open Access Journals (Sweden)

Riccardo Trinchero

2017-01-01

Full Text Available This paper presents a general purpose, algebraic tool—named TMsim—for the combined parametric and worst-case analysis of systems with bounded uncertain parameters. The tool is based on the theory of Taylor models and represents uncertain variables on a bounded domain in terms of a Taylor polynomial plus an interval remainder accounting for truncation and round-off errors. This representation is propagated from inputs to outputs by means of a suitable redefinition of the involved calculations, in both scalar and matrix form. The polynomial provides a parametric approximation of the variable, while the remainder gives a conservative bound of the associated error. The combination between the bound of the polynomial and the interval remainder provides an estimation of the overall (worst-case bound of the variable. After a preliminary theoretical background, the tool (freely available online is introduced step by step along with the necessary theoretical notions. As a validation, it is applied to illustrative examples as well as to real-life problems of relevance in electrical engineering applications, specifically a quarter-car model and a continuous-time linear equalizer.

Early Detection of Parametric Roll Resonance on Container Ships

DEFF Research Database (Denmark)

Galeazzi, Roberto; Blanke, Mogens; Poulsen, Niels Kjølstad

2013-01-01

Parametric roll resonance on ships is a nonlinear phenomenon where waves encountered at twice the natural roll frequency can bring the vessel dynamics into a bifurcation mode and lead to extreme values of roll. Recent years have seen several incidents with dramatic damage to container vessels...... the ship's speed and course, to escape from the bifurcation condition. This paper proposes nonparametric methods to detect the onset of roll resonance and demonstrates their performance. Theoretical conditions for parametric resonance are revisited and are used to develop efficient methods to detect its...... on experimental data from model tests and on data from a container ship crossing the Atlantic during a storm....

Spin effect on parametric interactions of waves in magnetoplasmas

International Nuclear Information System (INIS)

Shahid, M.; Melrose, D. B.; Jamil, M.; Murtaza, G.

2012-01-01

The parametric decay instability of upper hybrid wave into low-frequency electromagnetic Shear Alfvén wave and Ordinary mode radiation (O-mode) has been investigated in an electron-ion plasma immersed in the uniform external magnetic field. Incorporating quantum effect due to electron spin, the fluid model has been used to investigate the linear and nonlinear response of the plasma species for three-wave coupling in a magnetoplasma. It is shown that the spin of electrons has considerable effect on the parametric decay of upper hybrid wave into Ordinary mode radiation (O-mode) and Shear Alfvén wave even in classical regime.

A Study on Parametric Wave Estimation Based on Measured Ship Motions

DEFF Research Database (Denmark)

Nielsen, Ulrik Dam; Iseki, Toshio

2011-01-01

The paper studies parametric wave estimation based on the ‘wave buoy analogy’, and data and results obtained from the training ship Shioji-maru are compared with estimates of the sea states obtained from other measurements and observations. Furthermore, the estimating characteristics of the param......The paper studies parametric wave estimation based on the ‘wave buoy analogy’, and data and results obtained from the training ship Shioji-maru are compared with estimates of the sea states obtained from other measurements and observations. Furthermore, the estimating characteristics...... of the parametric model are discussed by considering the results of a similar estimation concept based on Bayesian modelling. The purpose of the latter comparison is not to favour the one estimation approach to the other but rather to highlight some of the advantages and disadvantages of the two approaches....

Measuring economy-wide energy efficiency performance: A parametric frontier approach

International Nuclear Information System (INIS)

Zhou, P.; Ang, B.W.; Zhou, D.Q.

2012-01-01

This paper proposes a parametric frontier approach to estimating economy-wide energy efficiency performance from a production efficiency point of view. It uses the Shephard energy distance function to define an energy efficiency index and adopts the stochastic frontier analysis technique to estimate the index. A case study of measuring the economy-wide energy efficiency performance of a sample of OECD countries using the proposed approach is presented. It is found that the proposed parametric frontier approach has higher discriminating power in energy efficiency performance measurement compared to its nonparametric frontier counterparts.

Comparison of Parametrization Techniques for an Electrical Circuit Model of Lithium-Sulfur Batteries

DEFF Research Database (Denmark)

Knap, Vaclav; Stroe, Daniel Loan; Teodorescu, Remus

2015-01-01

on the comparison of different parametrization methods of electrical circuit models (ECMs) for Li-S batteries. These methods are used to parametrize an ECM based on laboratory measurements performed on a Li-S pouch cell. Simulation results of ECMs are presented and compared against measurement values...

Effects of three-body interactions in the parametric and modulational instabilities of Bose–Einstein condensates

International Nuclear Information System (INIS)

Wamba, Etienne; Mohamadou, Alidou; Ekogo, Thierry B.; Atangana, Jacque; Kofane, Timoleon C.

2011-01-01

The parametric modulational instability for a discrete nonlinear Schrödinger equation with a cubic–quintic nonlinearity is analyzed. This model describes the dynamics of BECs, with both two- and three-body interatomic interactions trapped in an optical lattice. We identify and discuss the salient features of the three-body interaction in the parametric modulational instability. It is shown that the three-body interaction term can both, shift as well as narrow the window of parametric instability, and also change the behavior of a modulationally stable and parametrically unstable BEC with attractive two-body interaction. We explore this instability through the multiple-scale analysis and identify it numerically. The effect of the three body losses have also been investigated. -- Highlights: ► The parametric MI for the 1D GPE with a cubic–quintic nonlinearity is analyzed. ► The two- and three-body recombination and time-dependent scattering length is considered. ► We generate bright matter waves soliton through MI.

Global chaos synchronization of coupled parametrically excited ...

Indian Academy of Sciences (India)

In this paper, we study the synchronization behaviour of two linearly coupled parametrically excited chaotic pendula. The stability of the synchronized state is examined using Lyapunov stability theory and linear matrix inequality (LMI); and some sufficient criteria for global asymptotic synchronization are derived from which ...

Language Emptiness of Continuous-Time Parametric Timed Automata

DEFF Research Database (Denmark)

Benes, Nikola; Bezdek, Peter; Larsen, Kim Guldstrand

2015-01-01

Parametric timed automata extend the standard timed automata with the possibility to use parameters in the clock guards. In general, if the parameters are real-valued, the problem of language emptiness of such automata is undecidable even for various restricted subclasses. We thus focus on the case...... where parameters are assumed to be integer-valued, while the time still remains continuous. On the one hand, we show that the problem remains undecidable for parametric timed automata with three clocks and one parameter. On the other hand, for the case with arbitrary many clocks where only one......-time semantics only. To the best of our knowledge, this is the first positive result in the case of continuous-time and unbounded integer parameters, except for the rather simple case of single-clock automata....

Effects of quadratic and cubic nonlinearities on a perfectly tuned parametric amplifier

DEFF Research Database (Denmark)

Neumeyer, Stefan; Sorokin, Vladislav; Thomsen, Jon Juel

2016-01-01

We consider the performance of a parametric amplifier with perfect tuning (two-to-one ratio between the parametric and direct excitation frequencies) and quadratic and cubic nonlinearities. A forced Duffing–Mathieu equation with appended quadratic nonlinearity is considered as the model system......, and approximate analytical steady-state solutions and corresponding stabilities are obtained by the method of varying amplitudes. Some general effects of pure quadratic, and mixed quadratic and cubic nonlinearities on parametric amplification are shown. In particular, the effects of mixed quadratic and cubic...... nonlinearities may generate additional amplitude–frequency solutions. In this case an increased response and a more phase sensitive amplitude (phase between excitation frequencies) is obtained, as compared to the case with either pure quadratic or cubic nonlinearity. Furthermore, jumps and bi...

Determinant of flexible Parametric Estimation of Mixture Cure ...

African Journals Online (AJOL)

PROF. OLIVER OSUAGWA

2015-12-01

Dec 1, 2015 ... Suitability of four parametric mixture cure models were considered namely; Log .... regression analysis which relies on the ... The parameter of mixture cure fraction model was ..... Stochastic Models of Tumor Latency and Their.

Involute Spur Gear Template Development by Parametric Technique ...

African Journals Online (AJOL)

Nekky Umera

cylindrical coordinate systems to create the involute curve profile. Since spur gear ... Template gear development using parametric method means that the dimensions control the ... and rapid prototyping of interlocking gears. Excel is a common ...

Weak Form Efficiency of the Chittagong Stock Exchange: An Empirical Analysis (2006-2016

Directory of Open Access Journals (Sweden)

Shahadat Hussain

2017-01-01

Full Text Available We study the random walk behavior of Chittagong Stock Exchange (CSE by using daily returns of three indices for the period of 2006 to 2016 employing both non-parametric test (run test and parametric tests [autocorrelation coefficient test, Ljung– Box (LB statistics]. The skewness and kurtosis properties of daily return series are non-normal, with a hint of positively skewed and leptokurtic distribution. The results of run test; autocorrelation and Ljung–Box (LB statistics provide evidences against random walk behavior in the Chittagong Stock Exchange. Overall our result suggest that Chittagong Stock Exchange does not exhibit weak form of efficiency. Hence, there is opportunity of generating a superior return by the active investors.

Parametric Study of Sealant Nozzle

Science.gov (United States)

Yamamoto, Yoshimi

It has become apparent in recent years the advancement of manufacturing processes in the aerospace industry. Sealant nozzles are a critical device in the use of fuel tank applications for optimal bonds and for ground service support and repair. Sealants has always been a challenging area for optimizing and understanding the flow patterns. A parametric study was conducted to better understand geometric effects of sealant flow and to determine whether the sealant rheology can be numerically modeled. The Star-CCM+ software was used to successfully develop the parametric model, material model, physics continua, and simulate the fluid flow for the sealant nozzle. The simulation results of Semco sealant nozzles showed the geometric effects of fluid flow patterns and the influences from conical area reduction, tip length, inlet diameter, and tip angle parameters. A smaller outlet diameter induced maximum outlet velocity at the exit, and contributed to a high pressure drop. The conical area reduction, tip angle and inlet diameter contributed most to viscosity variation phenomenon. Developing and simulating 2 different flow models (Segregated Flow and Viscous Flow) proved that both can be used to obtain comparable velocity and pressure drop results, however; differences are seen visually in the non-uniformity of the velocity and viscosity fields for the Viscous Flow Model (VFM). A comprehensive simulation setup for sealant nozzles was developed so other analysts can utilize the data.

Plug and Play Robust Distributed Control with Ellipsoidal Parametric Uncertainty System

Directory of Open Access Journals (Sweden)

Hong Wang-jian

2016-01-01

Full Text Available We consider a continuous linear time invariant system with ellipsoidal parametric uncertainty structured into subsystems. Since the design of a local controller uses only information on a subsystem and its neighbours, we combine the plug and play idea and robust distributed control to propose one distributed control strategy for linear system with ellipsoidal parametric uncertainty. Firstly for linear system with ellipsoidal parametric uncertainty, a necessary and sufficient condition for robust state feedback control is proposed by means of linear matrix inequality. If this necessary and sufficient condition is satisfied, this robust state feedback gain matrix can be easily derived to guarantee robust stability and prescribed closed loop performance. Secondly the plug and play idea is introduced in the design process. Finally by one example of aircraft flutter model parameter identification, the efficiency of the proposed control strategy can be easily realized.

Research on Mixer Parametric Modeling System Based on Redevelopment of ANSYS

Directory of Open Access Journals (Sweden)

Bin Zheng

2015-01-01

Full Text Available In this paper, the mixer parametric modeling system software was developed by using VB which was taken as the foreground development program, and the paper combined with ANSYS software to create the finite element model of mixer blade and cylinder for the following numerical simulation of the flow field and parameter optimization of mixer. The software user interface was developed by VB and the pre-process model was created by invoking APDL of ANSYS in background. Therefore, the operation of modeling, meshing, component-building of mixer blade and cylinder were completed by using APDL and the graphic and text were outputted and displayed on the mixer parametric modeling system user interface which was developed by VB. Practice proved that it is convenient to modify the mixer solid model created by the parametric design language of ANSYS due to the similar structure.

Using Parametrics to Facilitate Collaborative Urban Design

DEFF Research Database (Denmark)

Steinø, Nicolai; Benbih, Karima; Obeling, Esben

2013-01-01

in the context of the urban South which is characterized by high urban growth rates, weak planning systems and modest means. The current state of planning and urban development in Morocco is introduced as a context for discussing collaborative urban design and parametric urban design, and some tentative...

Radiation parametric generation in non-linear crystals

International Nuclear Information System (INIS)

Pacheco, M.T.; Pereira, M.A.C.Q.

1983-01-01

A short historical development review is presented on the optical parametric oscillators. Analysis on behaviour of the simple resonant oscillators (SRO), double resonant oscillators (DRO) and ring resonant oscillators (RRO), in the plane wave pumping approximation is shown. Comparision between the three oscillators types is given. (Author) [pt

PARAMETRIC MODELING, CREATIVITY, AND DESIGN: TWO EXPERIENCES WITH ARCHITECTURE’ STUDENTS

Directory of Open Access Journals (Sweden)

Wilson Florio

2012-02-01

Full Text Available The aim of this article is to reflect on the use of the parametric modeling in two didactic experiences. The first experiment involved resources of the Paracloud program and its relation with the Rhinoceros program, that resulted in the production of physical models produced with the aid of the laser cutting. In the second experiment, the students had produced algorithms in the Grasshopper, resulting in families of structures and coverings. The study objects are both the physical models and digital algorithms resultants from this experimentation. For the analysis and synthesis of the results, we adopted four important assumptions: 1. the value of attitudes and environment of work; 2. the importance of experimentation and improvisation; 3. understanding of the design process as a situated act and as a ill-defined problem; 4. the inclusion of creative and critical thought in the disciplines. The results allow us to affirm that the parametric modeling stimulates creativity, therefore allowing combination of different parameters, that result in unexpected discoveries. Keywords: Teach-Learning, Parametric Modeling, Laser Cutter, Grasshopper, Design Process, Creativity.

Scaling of plasma turbulence resulting from parametric instabilities

International Nuclear Information System (INIS)

Ott, E.

1976-01-01

Dimensional analysis is used to obtain results on the turbulent state resulting from parametric instabilities of an initially cold plasma. The results include the possibility of an applied magnetic field, multiple ion species, and arbitrary dimensionality

First integrals and parametric solutions of third-order ODEs admitting {\\mathfrak{sl}(2, {R})}

Science.gov (United States)

Ruiz, A.; Muriel, C.

2017-05-01

A complete set of first integrals for any third-order ordinary differential equation admitting a Lie symmetry algebra isomorphic to sl(2, {R}) is explicitly computed. These first integrals are derived from two linearly independent solutions of a linear second-order ODE, without additional integration. The general solution in parametric form can be obtained by using the computed first integrals. The study includes a parallel analysis of the four inequivalent realizations of sl(2, {R}) , and it is applied to several particular examples. These include the generalized Chazy equation, as well as an example of an equation which admits the most complicated of the four inequivalent realizations.

Point interactions of the dipole type defined through a three-parametric power regularization

International Nuclear Information System (INIS)

Zolotaryuk, A V

2010-01-01

A family of point interactions of the dipole type is studied in one dimension using a regularization by rectangles in the form of a barrier and a well separated by a finite distance. The rectangles and the distance are parametrized by a squeezing parameter ε → 0 with three powers μ, ν and τ describing the squeezing rates for the barrier, the well and the distance, respectively. This parametrization allows us to construct a whole family of point potentials of the dipole type including some other point interactions, such as e.g. δ-potentials. Varying the power τ, it is possible to obtain in the zero-range limit the following two cases: (i) the limiting δ'-potential is opaque (the conventional result obtained earlier by some authors) or (ii) this potential admits a resonant tunneling (the opposite result obtained recently by other authors). The structure of resonances (if any) also depends on a regularizing sequence. The sets of the {μ, ν, τ}-space where a non-zero (resonant or non-resonant) transmission occurs are found. For all these cases in the zero-range limit the transfer matrix is shown to be with real parameters χ and g depending on a regularizing sequence. Those cases when χ ≠ 1 and g ≠ 0 mean that the corresponding δ'-potential is accompanied by an effective δ-potential.

Quantum tomography enhanced through parametric amplification

Science.gov (United States)

Knyazev, E.; Spasibko, K. Yu; Chekhova, M. V.; Khalili, F. Ya

2018-01-01

Quantum tomography is the standard method of reconstructing the Wigner function of quantum states of light by means of balanced homodyne detection. The reconstruction quality strongly depends on the photodetectors quantum efficiency and other losses in the measurement setup. In this article we analyze in detail a protocol of enhanced quantum tomography, proposed by Leonhardt and Paul [1] which allows one to reduce the degrading effect of detection losses. It is based on phase-sensitive parametric amplification, with the phase of the amplified quadrature being scanned synchronously with the local oscillator phase. Although with sufficiently strong amplification the protocol enables overcoming any detection inefficiency, it was so far not implemented in the experiment, probably due to the losses in the amplifier. Here we discuss a possible proof-of-principle experiment with a traveling-wave parametric amplifier. We show that with the state-of-the-art optical elements, the protocol enables high fidelity tomographic reconstruction of bright non-classical states of light. We consider two examples: bright squeezed vacuum and squeezed single-photon state, with the latter being a non-Gaussian state and both strongly affected by the losses.

A parametric model for the global thermodynamic behavior of fluids in the critical region

International Nuclear Information System (INIS)

Luettmer-Strathmann, J.; Tang, S.; Sengers, J.V.

1992-01-01

The asymptotic thermodynamic behavior of fluids near the critical point is described by scaling laws with universal scaling functions that can be represented by parametric equations. In this paper, we derive a more general parametric model that incorporates the crossover from singular thermodynamic behavior near the critical point to regular classical thermodynamic behavior far away from the critical point. Using ethane as an example, we show that such a parametric crossover model yields an accurate representation of the thermodynamic properties of fluids in a large region around the critical point

Parametric Model for Astrophysical Proton-Proton Interactions and Applications

Energy Technology Data Exchange (ETDEWEB)

Karlsson, Niklas [KTH Royal Institute of Technology, Stockholm (Sweden)

2007-01-01

Observations of gamma-rays have been made from celestial sources such as active galaxies, gamma-ray bursts and supernova remnants as well as the Galactic ridge. The study of gamma rays can provide information about production mechanisms and cosmic-ray acceleration. In the high-energy regime, one of the dominant mechanisms for gamma-ray production is the decay of neutral pions produced in interactions of ultra-relativistic cosmic-ray nuclei and interstellar matter. Presented here is a parametric model for calculations of inclusive cross sections and transverse momentum distributions for secondary particles--gamma rays, e^±, v_e, $\\bar{v}$_e, v_μ and $\\bar{μ}$_e--produced in proton-proton interactions. This parametric model is derived on the proton-proton interaction model proposed by Kamae et al.; it includes the diffraction dissociation process, Feynman-scaling violation and the logarithmically rising inelastic proton-proton cross section. To improve fidelity to experimental data for lower energies, two baryon resonance excitation processes were added; one representing the Δ(1232) and the other multiple resonances with masses around 1600 MeV/c². The model predicts the power-law spectral index for all secondary particle to be about 0.05 lower in absolute value than that of the incident proton and their inclusive cross sections to be larger than those predicted by previous models based on the Feynman-scaling hypothesis. The applications of the presented model in astrophysics are plentiful. It has been implemented into the Galprop code to calculate the contribution due to pion decays in the Galactic plane. The model has also been used to estimate the cosmic-ray flux in the Large Magellanic Cloud based on HI, CO and gamma-ray observations. The transverse momentum distributions enable calculations when the proton distribution is anisotropic. It is shown that the gamma-ray spectrum and flux due to a

Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion

Science.gov (United States)

Cho, Minhaeng

2018-05-01

Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion.

Science.gov (United States)

Cho, Minhaeng

2018-05-14

Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

Characterization of tunable light source by optical parametric oscillator for high resolution spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Wu, J. W. [Ewha Womens Univ., Seoul (Korea); Rhee, B. G. [Sejong Univ., Seoul (Korea); Park, S. W. [Yonsei Univ., Seoul (Korea); Noh, J. W. [Inha Univ., Incheon (Korea)

1998-04-01

A tunable light source is developed by the optical parametric oscillator, which is very useful for a high resolution spectroscopy. The electronic structure of molecules and atoms can be examined by a proper coherent light source. Optical parametric oscillator provides light sources stable and widely tunable. In this work, the characteristics of the parametric optical generation are examined in the LiNbO{sub 3}. The theoretical analysis as well as the experimental measurement is performed. The pump laser is a second harmonic of Nd:YAG laser, and the parametric gain is measured. The characteristics of singly resonant oscillator and doubly resonant oscillator is studied as a function of temperature. It is found that 1mole% MgO:LiNbO{sub 3} crystal provides the tunability from 0.6{mu}m to 3.0{mu}m wavelength. Both the critical and noncritical phase matching are studied. The optical damage occurring in a congruent LiNbO{sub 3} crystal was not observed in 1mole% MgO:LiNbO{sub 3} crystal, opening a possibility for a high power optical parametric oscillation generation. The current work can be extended to an experiment employing the fundamental Nd:YAG as pump to provide a coherent light source for the study of molecular vibrations. 28 refs., 14 figs., 3 tabs. (Author)

Generalized Correlation Coefficient for Non-Parametric Analysis of Microarray Time-Course Data

DEFF Research Database (Denmark)

Tan, Qihua; Thomassen, Mads; Burton, Mark

2017-01-01

the heterogeneous time-course gene expression patterns. Application of the method identified nonlinear time-course patterns in high agreement with parametric analysis. We conclude that the non-parametric nature in the generalized correlation analysis could be an useful and efficient tool for analyzing microarray...... time-course data and for exploring the complex relationships in the omics data for studying their association with disease and health....

A microcomputer based multi parametric system for nuclear data acquisition and processing

International Nuclear Information System (INIS)

Toledo Acosta B, Rene; Osorio Deliz F, Juan; Arista Romeu, Eduardo; Perez Sanchez, Reinaldo; Lopes Torres, E.

1997-01-01

A four-parameter Multi parametric System for the acquisition and processing of nuclear data is described. It is characterized for its flexibility and relatively low cost, also guaranteeing a high acquisition capacity. The system allows to be utilized in a multi parametric manner, in pulse height analysis or in many combination of both for parameter. It is described the hardware and the software of the system

A Hybrid Wind-Farm Parametrization for Mesoscale and Climate Models

Science.gov (United States)

Pan, Yang; Archer, Cristina L.

2018-04-01

To better understand the potential impact of wind farms on weather and climate at the regional to global scales, a new hybrid wind-farm parametrization is proposed for mesoscale and climate models. The proposed parametrization is a hybrid model because it is not based on physical processes or conservation laws, but on the multiple linear regression of the results of large-eddy simulations (LES) with the geometric properties of the wind-farm layout (e.g., the blockage ratio and blockage distance). The innovative aspect is that each wind turbine is treated individually based on its position in the farm and on the wind direction by predicting the velocity upstream of each turbine. The turbine-induced forces and added turbulence kinetic energy (TKE) are first derived analytically and then implemented in the Weather Research and Forecasting model. Idealized simulations of the offshore Lillgrund wind farm are conducted. The wind-speed deficit and TKE predicted with the hybrid model are in excellent agreement with those from the LES results, while the wind-power production estimated with the hybrid model is within 10% of that observed. Three additional wind farms with larger inter-turbine spacing than at Lillgrund are also considered, and a similar agreement with LES results is found, proving that the hybrid parametrization works well with any wind farm regardless of the spacing between turbines. These results indicate the wind-turbine position, wind direction, and added TKE are essential in accounting for the wind-farm effects on the surroundings, for which the hybrid wind-farm parametrization is a promising tool.

Jumps and bi-stability in the phase-gain characteristics of a nonlinear parametric amplifier

DEFF Research Database (Denmark)

Neumeyer, Stefan; van de Looij, Ruud; Thomsen, Jon Juel

2014-01-01

This work experimentally investigates the impact of nonlinearity on macromechanical parametric amplification. For a strong cubic stiffness nonlinearity we observe jumps in gain (ratio of steady-state vibration amplitude of the externally and parametrically excited system, to vibration amplitude o...

Clinical Alarms in intensive care: implications of alarm fatigue for the safety of patients1

Science.gov (United States)

Bridi, Adriana Carla; Louro, Thiago Quinellato; da Silva, Roberto Carlos Lyra

2014-01-01

OBJECTIVES: to identify the number of electro-medical pieces of equipment in a coronary care unit, characterize their types, and analyze implications for the safety of patients from the perspective of alarm fatigue. METHOD: this quantitative, observational, descriptive, non-participatory study was conducted in a coronary care unit of a cardiology hospital with 170 beds. RESULTS: a total of 426 alarms were recorded in 40 hours of observation: 227 were triggered by multi-parametric monitors and 199 were triggered by other equipment (infusion pumps, dialysis pumps, mechanical ventilators, and intra-aortic balloons); that is an average of 10.6 alarms per hour. CONCLUSION: the results reinforce the importance of properly configuring physiological variables, the volume and parameters of alarms of multi-parametric monitors within the routine of intensive care units. The alarms of equipment intended to protect patients have increased noise within the unit, the level of distraction and interruptions in the workflow, leading to a false sense of security. PMID:25591100

Characterization and durability testing of a glass-bonded ceramic waste form

International Nuclear Information System (INIS)

Johnson, S. G.

1998-01-01

Argonne National Laboratory is developing a glass bonded ceramic waste form for encapsulating the fission products and transuranics from the conditioning of metallic reactor fuel. This waste form is currently being scaled to the multi-kilogram size for encapsulation of actual high level waste. This paper will present characterization and durability testing of the ceramic waste form. An emphasis on results from application of glass durability tests such as the Product Consistency Test and characterization methods such as X-ray diffraction and scanning electron microscopy. The information presented is based on a suite of tests utilized for assessing product quality during scale-up and parametric testing

High average power scaling of optical parametric amplification through cascaded difference-frequency generators

Science.gov (United States)

Jovanovic, Igor; Comaskey, Brian J.

2004-09-14

A first pump pulse and a signal pulse are injected into a first optical parametric amplifier. This produces a first amplified signal pulse. At least one additional pump pulse and the first amplified signal pulse are injected into at least one additional optical parametric amplifier producing an increased power coherent optical pulse.

Evaluating forest management policies by parametric linear programing

Science.gov (United States)

Daniel I. Navon; Richard J. McConnen

1967-01-01

An analytical and simulation technique, parametric linear programing explores alternative conditions and devises an optimal management plan for each condition. Its application in solving policy-decision problems in the management of forest lands is illustrated in an example.

Parametric optimization of CNC end milling using entropy ...

African Journals Online (AJOL)

Parametric optimization of CNC end milling using entropy measurement technique combined with grey-Taguchi method. ... International Journal of Engineering, Science and Technology ... Keywords: CNC end milling, surface finish, material removal rate (MRR), entropy measurement technique, Taguchi method ...

Non-parametric smoothing of experimental data

International Nuclear Information System (INIS)

Kuketayev, A.T.; Pen'kov, F.M.

2007-01-01

Full text: Rapid processing of experimental data samples in nuclear physics often requires differentiation in order to find extrema. Therefore, even at the preliminary stage of data analysis, a range of noise reduction methods are used to smooth experimental data. There are many non-parametric smoothing techniques: interval averages, moving averages, exponential smoothing, etc. Nevertheless, it is more common to use a priori information about the behavior of the experimental curve in order to construct smoothing schemes based on the least squares techniques. The latter methodology's advantage is that the area under the curve can be preserved, which is equivalent to conservation of total speed of counting. The disadvantages of this approach include the lack of a priori information. For example, very often the sums of undifferentiated (by a detector) peaks are replaced with one peak during the processing of data, introducing uncontrolled errors in the determination of the physical quantities. The problem is solvable only by having experienced personnel, whose skills are much greater than the challenge. We propose a set of non-parametric techniques, which allows the use of any additional information on the nature of experimental dependence. The method is based on a construction of a functional, which includes both experimental data and a priori information. Minimum of this functional is reached on a non-parametric smoothed curve. Euler (Lagrange) differential equations are constructed for these curves; then their solutions are obtained analytically or numerically. The proposed approach allows for automated processing of nuclear physics data, eliminating the need for highly skilled laboratory personnel. Pursuant to the proposed approach is the possibility to obtain smoothing curves in a given confidence interval, e.g. according to the χ 2 distribution. This approach is applicable when constructing smooth solutions of ill-posed problems, in particular when solving

Frequency comb generation in a continuously pumped optical parametric oscillator

Science.gov (United States)

Mosca, S.; Parisi, M.; Ricciardi, I.; Leo, F.; Hansson, T.; Erkintalo, M.; Maddaloni, P.; De Natale, P.; Wabnitz, S.; De Rosa, M.

2018-02-01

We demonstrate optical frequency comb generation in a continuously pumped optical parametric oscillator, in the parametric region around half of the pump frequency. We also model the dynamics of such quadratic combs using a single time-domain mean-field equation, and obtain simulation results that are in good agreement with experimentally observed spectra. Moreover, we numerically investigate the coherence properties of simulated combs, showing the existence of correlated and phase-locked combs. Our work could pave the way for a new class of frequency comb sources, which may enable straightforward access to new spectral regions and stimulate novel applications of frequency combs.

Spectral linewidth preservation in parametric frequency combs seeded by dual pumps.

Science.gov (United States)

Tong, Zhi; Wiberg, Andreas O J; Myslivets, Evgeny; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

2012-07-30

We demonstrate new technique for generation of programmable-pitch, wideband frequency combs with low phase noise. The comb generation was achieved using cavity-less, multistage mixer driven by two tunable continuous-wave pump seeds. The approach relies on phase-correlated continuous-wave pumps in order to cancel spectral linewidth broadening inherent to parametric comb generation. Parametric combs with over 200-nm bandwidth were obtained and characterized with respect to phase noise scaling to demonstrate linewidth preservation over 100 generated tones.

Computing Optimal Stochastic Portfolio Execution Strategies: A Parametric Approach Using Simulations

Science.gov (United States)

Moazeni, Somayeh; Coleman, Thomas F.; Li, Yuying

2010-09-01

Computing optimal stochastic portfolio execution strategies under appropriate risk consideration presents great computational challenge. We investigate a parametric approach for computing optimal stochastic strategies using Monte Carlo simulations. This approach allows reduction in computational complexity by computing coefficients for a parametric representation of a stochastic dynamic strategy based on static optimization. Using this technique, constraints can be similarly handled using appropriate penalty functions. We illustrate the proposed approach to minimize the expected execution cost and Conditional Value-at-Risk (CVaR).