sammy multilevel r-matrix: Topics by WorldWideScience.org

Impact of the "2"3"5U covariance data in benchmark calculations

In 1980 the multilevel multichannel R-matrix code SAMMY was released for use in analysis of neutron data at the Oak Ridge Electron Linear Accelerator. Since that time, SAMMY has undergone significant modifications: (1) User-friendly options have been incorporated to streamline common operations and to protect a run from common user errors, (2) The Reich-Moore formalism has been extended to include an optional logarithmic parameterization of the external R-matrix, for which any or all parameters may be varied, (3) the ability to vary sample thickness, effective temperature, matching radius, and/or resolution-broadening parameters has been incorporated, (4) to avoid loss of information (i.e. computer round-off errors) between runs, the ''covariance file'' now includes precise values for al variables, (5) Unused but correlated variables may be included in the analysis. Because of these ...

The {sup 234}U neutron capture cross section measurement at the n TOF facility

The error estimation for calculated quantities relies on nuclear data uncertainty information available in the basic nuclear data libraries such as the U.S. Evaluated Nuclear Data File (ENDF/B). The uncertainty files (covariance matrices) in the ENDF/B library are generally obtained from analysis of experimental data. In the resonance region, the computer code SAMMY is used for analyses of experimental data and generation of resonance parameters. In addition to resonance parameters evaluation, SAMMY also generates resonance parameter covariance matrices (RPCM). SAMMY uses the generalized least-squares formalism (Bayes' method) together with the resonance formalism (R-matrix theory) for analysis of experimental data. Two approaches are available for creation of resonance-parameter covariance data. (1) During the data-evaluation process, SAMMY generates both a set of resonance ...

2008-09-14

Novel Multi-Level PWM Inverter Using The Common Arm

The neutron capture cross-section of {sup 234}U has been measured for energies from thermal up to the keV region in the neutron time-of-flight facility n-TOF, based on a spallation source located at CERN. A 4{pi} BaF{sub 2} array composed of 40 crystals, placed at a distance of 184.9 m from the neutron source, was employed as a total absorption calorimeter (TAC) for detection of the prompt {gamma}-ray cascade from capture events in the sample. This text describes the experimental setup, all necessary steps followed during the data analysis procedure. Results are presented in the form of R-matrix resonance parameters from fits with the SAMMY code and compared to the evaluated data of Endf in the relevant energy region, indicating the good performance of the n-TOF facility and the TAC. (authors)

2008-07-01

KoreaScience (Korea)

Full Text Available

2005-04-01

Neutron cross section measurements using the Oak Ridge electron linear accelerator

Use of shell model calculations in R-matrix studies of neutron-induced reactions

During this reporting period, the work supported under DOE Grant No. FG02-87ER40326.A003 has resulted in one publication, two papers submitted to Phys. Rev. C for publication, and one paper presented at a professional meeting. During this period, modifications were made to the interactive R-Matrix fitting computer program DSIG to include the total radiation widths in the R-Matrix calculation of the cross section. The R-Matrix analyses of n+{sup 90}Zr and n+{sup 208}Pn have already begun.

1990-08-01

Photovoltaic applications for off-grid electrification using novel multi-level inverter technology with energy storage

R-matrix analyses of neutron-induced reactions for many of the lightest p-shell nuclei are difficult due to a lack of distinct resonance structure in the reaction cross sections. Initial values for the required R-matrix parameters, E,sub(lambda) and ..gamma..sub(lambdac) for states in the compound system, can be obtained from shell model calculations. In the present work, the results of recent shell model calculations for the lithium isotopes have been used in R-matrix analyses of /sup 6/Li+n and /sup 7/Li+n reactions for E sub(n) < 8 MeV. Consequences of the shell model predictions for the level structure of /sup 7/Li and /sup 8/Li on the /sup 6/Li+n and /sup 7/Li+n reaction mechanisms and cross sections are discussed.

1986-01-01

British Library Electronic Table of Contents (United Kingdom)

In areas where grid connection is difficult and costly, the use of renewable energy is both economically and environmentally advantageous. Due to typically low system efficiency (10%) and intermittency of photovoltaic (PV) electricity generation, a new design of multi-level H-bridge inverter technology is considered. This multi-level technology increases DC to AC conversion efficiency and the design includes battery energy storage to enable 24/7 operation. The proposed multi-level inverter is compared and contrasted with other existing designs. The proposed cascaded inverter provides lower switching losses, simple switching techniques, modularity, and simpler charge-balancing approaches than conventional technology. A switching technique was designed for the proposed multi-level inverter t...

2012-01-01

Neutron Resonance Parameters and Covariance Matrix of 239Pu

Phenomenology of light systems using R-matrix theory.

In order to obtain the resonance parameters in a single energy range and the corresponding covariance matrix, a reevaluation of 239Pu was performed with the code SAMMY. The most recent experimental data were analyzed or reanalyzed in the energy range thermal to 2.5 keV. The normalization of the fission cross section data was reconsidered by taking into account the most recent measurements of Weston et al. and Wagemans et al. A full resonance parameter covariance matrix was generated. The method used to obtain realistic uncertainties on the average cross section calculated by SAMMY or other processing codes was examined.

2008-08-01

Place matters: multilevel investigation of HIV distribution in Tanzania

Over the last 30 years, a program of R-matrix analyses has been carried out at Los Alamos in the mass range 2 {le} A {le} 18 that gives useful information about the light systems. These analyses provide data for astrophysics, as well as for neutronic and thermonuclear applications, and can yield important constraints from the experimental measurements on the nature of few-body interactions. Following a brief introduction to R-matrix theory, I will describe recent work on reactions in the A=2 (NN) and A=4 systems. Finally, some comments will be made about extending the theory to complex energies in order to obtain information about resonances and other types of S-matrix singularities.

2001-01-01

A stem cell niche dominance theorem

ObjectiveTo examine the extent to which the regional and neighborhood distribution of HIV in Tanzania is caused by the differential distribution of individual correlates...Full Text Available

2008-03-30

Lattice W_N algebra and its quantization

BackgroundMultilevelness is a defining characteristic of complex systems. For example, in the intestinal tissue the epithelial lining is organized into crypts that are maintained...Full Text Available

Multilevel support vector regression analysis to identify condition-specific regulatory networks

We consider the integrable structure of the quantum lattice W_N algebras. We introduce the ultralocal Lax matrix, and show that the Yang-Baxter relation is satisfied with a Z_N invariant R-matrix. (orig.).

1997-11-01

NAME=\\

Wastenet

...Programme Manager Interests Multilevel Statistical Modelling Geography of Health and Health Care Geographical Data Analysis Census Data Analysis Health Services Research (in particular Research Design, Statistical Analysis and Epidemiology) people/mgould.html Homepage | Contacts | Site Map | Privacy Statement | Webmaster | ...

Effect of household and village characteristics on financial catastrophe and impoverishment due to health care spending in Western and Central Rural China: A multilevel analysis

Motivation: The identification of gene regulatory modules is an important yet challenging problem in computational biology. While many computational methods have been proposed to identify...Full Text Available

2010-06-01

Electron impact excitation of lithium-like iron

ObjectiveThe study aimed to examine the effect of household and community characteristics on financial catastrophe and impoverishment due to health payment in Western and Central...Full Text Available

Reevaluation of 58Ni and 60Ni Resonance Parameters in the Energy Range Thermal to 800 keV

Calculations of total and angle-differential excitation cross sections for the electron impact excitation of lithium-like iron were performed with the R-matrix formulation. The alignments of the excited states 1s{sup 2}np {sup 2}P{sub 3/2} are also presented for n=3 and 4 along with the angular photon distribution from these states to the ground state. Relativistic effects were included in the present calculations by the Breit-Pauli Hamiltonian.

1996-05-01

Re-evaluation of {sup 58}Ni and {sup 60}Ni resonance parameters in the neutron energy range thermal to 800 keV

The previous 58Ni and 60Ni set of resonance parameters (ENDF/B-VII-0, JEFF-3, etc.) was based on the SAMMY analysis of Oak Ridge National Laboratory neutron transmission, scattering cross section and capture cross section measurements by C. M. Perey et al. The present results were obtained by adding to the SAMMY experimental data base the capture cross sections measured recently at the Oak Ridge Linear Electron Accelerator by Guber et al. and the Geel Electron Linear Accelerator very high-resolution neutron transmission measurements performed by Brusegan et al. A complete resonance parameter covariance matrix (RPCM) was obtained from the SAMMY analysis of the experimental database. The data sets were made consistent, when needed, by adjusting the neutron energy scales, the normalization coefficients, and the background corrections. The RPCM allows the calculation of the cross section uncertainties due mainly to statistical ...

2009-09-01

Spontaneously generated atomic entanglement in free space: reinforced by incoherent pumping

The previous {sup 58}Ni and {sup 60}Ni set of resonance parameters (Endf/B7.O, Jeff-3, etc.) was based on the SAMMY analysis of Oak Ridge National Laboratory neutron transmission, scattering cross section and capture cross section measurements by C.M. Perey et al. The present results were obtained by adding to the SAMMY experimental database the capture cross sections measured recently at the Oak Ridge Linear Electron Accelerator by Guber et al. and the Geel Electron Linear Accelerator and very high-resolution neutron transmission measurements performed by Brusegan et al. A complete resonance parameter covariance matrix (RPCM) was obtained from the SAMMY analysis of the experimental database. The data sets were made consistent, when needed, by adjusting the neutron energy scales, the normalization coefficients, and the background corrections. The RPCM allows the calculation of the cross section uncertainties due mainly to ...

2009-07-01

CERN Document Server

We study spontaneously generated entanglement (SGE) between two identical multilevel atoms in free space via vacuum-induced radiative coupling. We show that the SGE in two-atom systems may initially increase with time but eventually vanishes in the time scale determined by the excited state lifetime and radiative coupling strength between the two atoms. We demonstrate that a steady-state SGE can be established by incoherently pumping the excited states of the two-atom system. We have shown that an appropriate rate of incoherent pump can help producing optimal SGE. The multilevel systems offer us more chanel to establish entanglement. The system under consideration could be realized in a tight trap or atoms/ions doped in a solid substrate.

2009-01-01

Multilevel analysis of effects of individual characteristics and household factors on self-rated health among older adults in rural Vietnam

British Library Electronic Table of Contents (United Kingdom)

Aim: This paper aims to describe self-rated health (SRH) status among older adults in a rural community of Vietnam, and examine individual and household-level factors associated with good health rating among the study populations. Methods: The study was carried out in the Bavi district, a rural community located 60 km west of Hanoi, the capital, within the Epidemiological Field Laboratory of Bavi (FilaBavi) in Vietnam in 2006. All people aged 50 years and over who lived within the district were surveyed. Face-to-face household interviews were conducted by trained surveyors using standard World Health Organization/INDEPTH network questionnaire-summary version. A logistic multilevel modeling approach was applied to analyze the association between SRH and both individual and household-level f...

2010-01-01

1 2 3

Effects of individual characteristics and school environment on cigarette smoking among students ages 13-15: A multilevel analysis of the 2007 Global Youth Tobacco Survey (GYTS) data from Vietnam

British Library Electronic Table of Contents (United Kingdom)

This paper aims to estimate the prevalence of cigarette smoking among students in Vietnam ages 13-15 and examines its relationship with compositional and contextual factors. The data used in this paper were obtained from the 2007 Global Youth Tobacco Survey conducted in nine provinces in Vietnam. A multilevel logistic regression model was applied to analyse the association between the current incidence of cigarette smoking and factors on both the individual and school level. The prevalence of cigarette smoking among students was 3.3% overall. The prevalence of smoking among male students (5.9%) was higher than that among females (1.2%). Parental smoking was a significant risk factor for smoking among the students. Having a friend who smoked was the strongest predictor of smoking status amo...

2011-01-01

The 2s{sup 1}2p{sup 4} autodetachment resonance in the C{sup -} negative ion

Adiabatic quantum computing with phase modulated laser pulses

The calculations of the photodetachment cross section for the C{sup -} negative ion has been performed within the newly-developed many-body theory method, the RPAE interchannel interaction and dynamic relaxation and polarization corrections being included. The 2s{sup 1}2p{sup 4} shape resonance is shifted to a higher photon energy and broadens as compared to the resonance parameters determined earlier within the RPAE, which is consistent with the experimental evidence and the recent R-matrix calculations. (orig.) 18 refs.

1998-08-10

Neutron Resonance Parameters of 55Mn from Reich-Moore Analysis of Recent Experimental Neutron Transmission and Capture Cross Sections

Implementation of quantum logical gates for multilevel systems is demonstrated through decoherence control under the quantum adiabatic method using simple phase modulated laser pulses. We make use of selective population inversion and Hamiltonian evolution with time to achieve such goals robustly instead of the standard unitary transformation language. (letter to the editor)

2005-09-23

Very high resolution measurements of the total cross section of natural iron

High-resolution neutron capture cross section measurements of 55Mn were recently performed at GELINA by Schillebeeckx et al. (2005) and at ORELA by Guber et al. (2007). The analysis of the experimental data was performed with the computer code SAMMY using the Bayesian approach in the resonance parameters representation of the cross sections. The neutron transmission data taken in 1988 by Harvey et al. (2007) and not analyzed before were added to the SAMMY experimental data base. More than 95% of the s-wave resonances and more than 85% of the p-wave resonances were identified in the energy range up to 125 keV, leading to the neutron strength functions S0 = (3.90 0.78) x 10-4 and S1 = (0.45 0.08) x 10-4. About 25% of the d-wave resonances were identified with a possible strength function of S2 = 1.0 x 10-4. The capture cross section calculated at 0.0253 eV is 13.27 b, and the capture resonance integral is 13.52 0.30 b. In the energy range 15 to ...

2008-05-01

R-matrices for highest weight representations of s-circumflexl{sub q}(2,C) at roots of unity

The total cross section of natural Fe has been measured with the GELINA pulsed white neutron source with a time-of-flight resolution of about 3.8 ps/m and good statistical precision. Measurements have been performed on three sample thicknesses including one with an average transmission of 0.1, in order to check for consistency and for remaining resolution effects. The cross sections in the {open_quotes}unresolved resonance region{close_quotes} still show rather strong fluctuations. These data will directly be used in shielding benchmark calculations. The resonance region data will be analysed by an R-matrix routine and the parameters be compared to existing compilations.

1994-12-31

Nuclear structure studies via neutron interactions

The general formula is obtained for R-matrices of s-circumflexl{sub q}(2,C) for the highest weight representations both for general q and for q being a root of unity by generalizing G. Gomez`s and Sierra`s one for semiperiodic representations of s-circumflexl{sub q}(2,C) at roots of unity. In a case of general q, direct matrix form is obtained for the well known Jimbo`s R-matrix. In a case of q{sup N}=1 for semiperiodic and spin j<(N-1)/2 representations the new R-matrices are obtained which together with Jimbo`s one obey the spectral parameter dependent Yang-Baxter equations. (author) 16 refs.

1992-10-01

Evidence for significant backscattering in near-threshold electron-impact excitation of Ar"7"+(3s#->#3p)

Research preformed consisted of: (1) publication of an experimental paper for the n + {sup 40}Ar high resolution total cross section and submission of a theoretical paper dealing with the prediction of the average parameters deduced from the the data; (2) preliminary R-matrix analysis of the neutron total cross section data for the n + {sup 208}Pb systems, up to an energy of 1.7 MeV; (3) completed the analysis of neutron total cross section of data for n + {sup 54}Fe up to energy of 500 keV, with j{sup {pi}} values confirmed, in most cases, by differential scattering data; (4) analysis of total cross section data for the n + {sup 88}Sr system up to an energy of 175 keV; (5) development of a graphical interface for the code RFUNC, used to calculate the differential scattering cross sections, for comparison with measurements.

1991-03-01

Absolute cross sections for near-threshold electron-impact excitation of the 3s"2"1S#->#3s3p"1P and 3s"2"1S#->#3s3p"3P transitions in Si"2"+

Measurements of absolute total cross sections for electron-impact excitation of Ar"7"+(3s#->#3p) using a merged-beams electron-energy-loss technique show that near threshold the inelastically scattered electrons are ejected primarily in the backward direction. This unusual angular scattering has not been previously observed for atoms or ions, but may be typical for multiply charged ions. The total cross sections, measured over an energy range to 2.2 eV above threshold, agree with seven-state R-matrix close-coupling calculations. Both close-coupling and distorted-wave calculations also confirm the backscattering observed in these measurements.

Hierarchical Kohonenen net for anomaly detection in network security.

Absolute total cross sections for electron-impact excitation of the 3s"2"1S#->#3s3p"3P and 3s"2"1S#->#3s3p"1P transitions in Si"2"+ were measured using the merged electron-ion beams energy-loss technique. The results are compared to R-matrix close-coupling theory, which predicts a strong resonance enhancement of the cross section near the threshold for excitation of the "3P state and this is confirmed by the experiments. The observed disagreement between theory and experiment for the dipole excitation is suggested to be due to resonance interference. copyright 1997 The American Physical Society.

Science.gov (United States)

A novel multilevel hierarchical Kohonen Net (K-Map) for an intrusion detection system is presented. Each level of the hierarchical map is modeled as a simple winner-take-all K-Map. One significant advantage of this multilevel hierarchical K-Map is its computational efficiency. Unlike other statistical anomaly detection methods such as nearest neighbor approach, K-means clustering or probabilistic analysis that employ distance computation in the feature space to identify the outliers, our approach does not involve costly point-to-point computation in organizing the data into clusters. Another advantage is the reduced network size. We use the classification capability of the K-Map on selected dimensions of data set in detecting anomalies. Randomly selected subsets that contain both attacks and normal records from the KDD Cup 1999 benchmark data are used to train the hierarchical net. We use a confidence measure to label the clusters. Then we use ...

2005-04-01

FP-tree and COFI Based Approach for Mining of Multiple Level Association Rules in Large Databases

CERN Document Server

In recent years, discovery of association rules among itemsets in a large database has been described as an important database-mining problem. The problem of discovering association rules has received considerable research attention and several algorithms for mining frequent itemsets have been developed. Many algorithms have been proposed to discover rules at single concept level. However, mining association rules at multiple concept levels may lead to the discovery of more specific and concrete knowledge from data. The discovery of multiple level association rules is very much useful in many applications. In most of the studies for multiple level association rule mining, the database is scanned repeatedly which affects the efficiency of mining process. In this research paper, a new method for discovering multilevel association rules is proposed. It is based on FP-tree structure and uses cooccurrence frequent item tree to find frequent items in ...

2010-01-01

Structures in the Universe and Origin of Galaxies

CERN Document Server

The analysis of images (of obtained in various ranges of the lengths of waves) of luminous objects in the Universe by means of a method of multilevel dynamic contrasting led author to the conclusions: a) the structures of all observable galaxies represents a complicated constructions which have the tendency to self-similarity and made of separate (basic) blocks, which are a coaxially tubular structures and a cartwheel-like structures; b) the majority of observable objects in the Universe are luminous butt-ends of almost invisible (of almost completely transparent) of filamentary formations which structures are seen only near to their luminous butt-ends; c) the result of analysis of images of cosmic objects show the structure of many pairs of cooperating galaxies point to opportunity of their formation at butt-ends generated in a place of break of the similar filament; d) the interacting galaxies (M 81 and M 82) show they are butt-ends of sawed off of two branches ...

2005-01-01

No evidence of over-reporting of SARS in mainland China

British Library Electronic Table of Contents (United Kingdom)

Summary Objective To find out whether there was over-reporting of SARS patients in mainland China in view of the relatively low case fatality ratio in mainland China, in comparison with other affected countries and areas. Methods We searched PubMed for all SARS antibody detection papers (in English or Chinese language) using the keywords `SARS' and `antibody'. Then the resulting articles were further read through to select the SARS detection results using ELISA methods of serum samples collected at least 1 month after disease onset. A multi-level logistic regression was applied to test for possible differences in the proportions positive between locations of the study. Results A total of 48 studies were identified, including 39 from mainland China and nine from elsewhere (Hong Kong, Taiwan...

2009-01-01

Multi-level energy analysis of emerging technologies: a case study in new materials for lithium ion batteries

British Library Electronic Table of Contents (United Kingdom)

A range of new nanomaterials to replace the active materials in lithium ion batteries are currently being studied and employed in an attempt to overcome various performance limitations of previous technologies. Nanomaterial production and manufacturing techniques appear to fit into a general trend towards more energy intensive production methods for high-tech goods. This does not necessarily imply an increase in lifecycle energy use; artefacts that consume or transform energy during use could possibly regain this increased initial input via increased efficiency in use. In particular, this paper highlights that larger gains could be possible if the artefact in question allows a given service to be provided via an alternative and more efficient system entirely.The lifecycle energy efficienci...

2011-01-01

Focused ion beam fabrication and properties of nanoscale Josephson junctions for sensors and other applications

Declining inter-industry wage dispersion in the US

The methods of superconducting device fabrication by lithography and multilevel processing usually require a number of processing steps with lithographic resolution and alignment adequate for the scale of the device be fabricated. As an alternative, the focused ion beam (FIB) microscope is increasingly being used directly to fabricate devices. A major advantage of using a FIB compared to other lithography methods is its flexibility and high resolution. It allows in-situ, milling (#propor to#5 nm at a beam current of 1 pA) to a variety of depths, and imaging (2 nm) of the sample. In this paper we describe our development of junction fabrication techniques using the FIB and their application in creating a range of potential sensor devices and quantum electronics applications. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

2005-03-01

British Library Electronic Table of Contents (United Kingdom)

Industrial effects have long been significant factors in wage inequality. Previous research indicates that wage differentials across industries were increasing through the mid 1980s. Using more recent data, however, we find that the level of inter-industry wage dispersion declined by 36% from 1986 to 2002 despite the continued trend towards increasing inequality in the labor force. This decline in inter-industry wage dispersion is evident across gender and educational groups. Using multilevel growth curve models, our multivariate results indicate that the decline is only weakly related to industrial changes in education, occupation or even productivity despite the fact that the latter variable had been a critical factor in the prior period. Indicators of globalization and downsizing also d...

2008-01-01

Decider: A fuzzy multi-criteria group decision support system

British Library Electronic Table of Contents (United Kingdom)

Multi-criteria group decision making (MCGDM) aims to support preference-based decision over the available alternatives that are characterized by multiple criteria in a group. To increase the level of overall satisfaction for the final decision across the group and deal with uncertainty in decision process, a fuzzy MCGDM process (FMP) model is established in this study. This FMP model can also aggregate both subjective and objective information under multi-level hierarchies of criteria and evaluators. Based on the FMP model, a fuzzy MCGDM decision support system (called Decider) is developed, which can handle information expressed in linguistic terms, boolean values, as well as numeric values to assess and rank a set of alternatives within a group of decision makers. Real applications indic...

2010-01-01

A social network-based organizational model for improving knowledge management in supply chains

British Library Electronic Table of Contents (United Kingdom)

Purpose - This paper seeks to provide a social network-based model for improving knowledge management in multi-level supply chains formed by small and medium-sized enterprises (SMEs). Design/methodology/approach - This approach uses social network analysis techniques to propose and represent a knowledge network for supply chains. Empirical experience from an exploratory case study in the construction sector is also presented. Findings - This proposal improves the establishment of inter-organizational relationships into networks to exchange knowledge among the companies along the supply chain and to create specific knowledge by promoting confidence and motivation. Originality/value - This proposed model is useful for academics and practitioners in supply chain management to gain a better un...

2011-01-01

Measurement of "2"3"3U(n,f) cross-section at n_TOF facility. Statistical analysis

B-spline methods for radial Dirac equations

The "2"3"3U(n, f) cross-section has been measured at n_TOF in a wide energy range with a dedicated fission ionization chamber. We report here the results from 0.30 meV to 1 MeV neutron energy. The "2"3"3U(n, f) cross-section has been determined relative to a reference sample of "2"3"5U(n, f) measured simultaneously with the same detector. The very high instantaneous neutron flux and the intrinsically low background of the n TOF installation result in an accuracy around 3% in the whole energy range, while the energy resolution of the neutron beam allows for an accurate description of the fission cross-section by means of R-matrix analysis over a wide energy range. The present data provide the basis for a more precise evaluation of the "2"3"3U fission cross-section, and for improving the reliability of databases needed for the design of new energy systems based on the Th/U cycle. (Author)

2009-02-01

The neutron capture cross sections of {sup 237}Np(n,{gamma}) and {sup 240}Pu(n,{gamma}) and its relevance in the transmutation of nuclear waste

Although B-spline techniques have been used to solve two-point boundary value problems with Dirac Hamiltonians for more than 20 years, the treatment of boundary conditions is still a matter of controversy. Spurious, non-physical, solutions are endemic when boundary conditions are not handled correctly. These pathological problems are absent when traditional finite difference methods are used as in computer packages such as GRASP. Accurate approximation using both finite differences and B-splines depends on controlling local approximation errors, and this common property suggests no a priori reason to suppose that B-spline algorithms should be more prone to generate spurious solutions. The relativistic Bloch operators of [24], when added to the Dirac differential operator, permit the construction of a self-adjoint differential operator for the two-point boundary value problem on a finite interval. Approximate solution of this problem exploiting the properties of B-splines in variational ...

2009-03-14

1 2 3

The EU as a frontrunner on greenhouse gas emissions trading. How did it happen and will the EU succeed?

Neutron capture cross sections of actinides are of great relevance for the Transmutation of Nuclear Waste in Accelerator Driven Systems (ADS) and Generation-IV reactors. The neutron capture cross sections of {sup 237}Np and {sup 240}Pu in the range of 1 eV to 2 keV were measured at the n-TOF facility with a Total Absorption Calorimeter. The data have been analyzed with the SAMMY code. The corresponding covariance matrices have been generated. The final cross sections are presented and compared to the previously existing ones.The n-TOF {sup 237}Np {sigma}(n,{gamma}) is in agreement with the evaluated data files below 300 eV and its is lower by 10 to 15% up to 2 keV. This discrepancy with the evaluated data files is also observed in the capture cross section derived from the transmission measurements of Gressier et al. In the case of the {sup 240}Pu {sigma}(n,{gamma}), the n-TOF {sigma}(n,{gamma}) agrees within uncertainties with JENDL-3.3 and JEFF-3.1, except for a ...

2008-07-01

Fabrication of single nanofluidic channels in poly(methylmethacrylate) films via focused-ion beam milling for use as molecular gates

The objective of this paper is first to provide empirical evidence of what can be seen as a rather remarkable change in EU's position on the use of greenhouse gas (GHG) emissions trading (ET) in climate policy, from the role of a sceptic in the run-up to Kyoto towards more of a frontrunner. The paper argues that there is a synergistic and multilevel mix of explanatory factors for this 'U-turn', including developments at the international, EU, Member State, sub-national, and even down to the personal level. Second, the paper explores and discusses the philosophy behind the Commission's proposal for a directive on GHG ET. Third, the paper examines the prospects for 'success' of a scheme for EU-wide ET using a multifaceted set of metrics. In brief, we argue that output success - the chances for having a directive adopted - hinges on the resolution of two key issues. First, whether the preliminary phase is to be ...

2003-07-01

A novel nanoglue and whole wafer self-alignment based upon self-assembled monolayers

Focused-ion beam (FIB) milling provides rapid fabrication of individual cylindrical submicrometer channels with reproducible dimensions (#+-#5% diameters) through 8-#mu#m thick poly(methylmethacrylate) (PMMA) films. PMMA films are spincast on sacrificial Si carriers and sputter-coated with Au before the 30-kV gallium FIB milling process. By adding a trace amount of poly(ethyleneoxide) and poly(dimethylsiloxane) to the PMMA solution before casting, the films can be released for subsequent mounting in microfluidic devices to create hybrid microfluidic-nanofluidic multilevel architectures. In situ FIB sectioning demonstrates the smooth cylindrical surface within the pore. Placing a milled film in contact with an aqueous fluorescein solution fills the channel by capillary action, as verified by confocal fluorescence microscopy. Confocal fluorescence of dyed films reveals that the pores span the thickness of the PMMA film. Small arrays of channels with a defined number ...

2004-08-16

Science.gov (United States)

New methodologies for fabrication of multilevel packaging, particularly for RF signal analysis, are investigated. A new method for ``gluing'' silicon wafers together with a Self Assembled Monolayers (SAMs) based nanoglue are discussed, as are methods to enable its use with nonconforming wafers. Results of bond strength measurements as a function of temperature and process will be presented. Surface area bonded is characterized by infrared (IR) imaging. We will also present a method of inducing self-alignment between whole silicon wafers with micrometer precision. This represents a qualitative departure from alignment of millimeter-sized object as has been previously demonstrated. Self-alignment is induced by creating hydrophilic and hydrophobic regions on the wafers and using capillary forces of water in these regions to force the wafers to align with little to no outside influence. Results are characterized by IR imaging. Physical ideas that enable the whole-wafer ...

2008-10-01

One-photon two-electron processes in helium close to the double ionization threshold; Diexcitation electronique de l'helium par un photon au voisinage du seuil de double ionisation

High-accuracy "2"3"3U(n,f) cross-section measurement at the white-neutron source n_TOF from near-thermal to 1 MeV neutron energy

This work presents a study of the {sup 1}P{sup 0} excited states of He that can be reached by absorption of a single photon carrying an energy close to the double ionization threshold (DIT) (79 eV). Above the DIT, these states are the double continuum states; below, they are the double excited states. These two types of states are tightly coupled to the single continuum states with or without excitation of the residual ion He{sup +}, owing to their degeneracy in energy. In a one-photon process, these states can only be formed owing to the electronic correlations in the system which must be well described to obtain quantitative good results. Our study is a part of the work which aims at a united description of all these doubly excited, ionized-excited, and double continuum states. We use the Hyperspherical R-Matrix with Semiclassical Outgoing Waves (HRM-SOW) method, initially dedicated to double photoionization studies. We extend it to extract information on the ...

2007-04-15

Electron-ion recombination of neutral iron

The "2"3"3U(n,f) cross section has been measured at the white neutron source n_TOF in a wide energy range with a dedicated fission ionization chamber. We report here the results from #approx#30 meV to 1 MeV neutron energy. The "2"3"3U(n,f) cross section has been determined relative to a reference sample of "2"3"5U(n,f) measured simultaneously with the same detector. The very high instantaneous neutron flux and the intrinsically low background of the n_TOF installation result in an accuracy around 3% in the whole energy range, while the energy resolution of the neutron beam allows for an accurate description of the fission cross section by means of R-matrix analysis over a wide energy range. The results are, in general, in good agreement with the most recent high-accuracy measurement of this fission cross section, over the more limited range of the previous measurements, and indicated that even the latest evaluations underestimate the cross section in the epithermal ...

2009-10-01