356 Matching Results

Search Results

Advanced search parameters have been applied.

(e,e'N) Reactions

Description: With the advent of a new generation of high energy, high duty cycle electron accelerators, a whole range of new nuclear and subnuclear phenomena can be investigated, in particular through coincidence experiments.This contribution focuses on one and two nucleon emission studies below pion threshold.After a brief review of recent experimental and theoretical work, the study of single nucleon densities through high energy (e,e'N) experiments is discussed.New insights in short-range multihadron phenomena are likely to be obtained through (e,e'p), (e,e'd) and (e,e'2N) reactions.Coincidence experiments, some of them involving polarization measurement, are described to study the free and bound nucleon electromagnetic responses.
Date: January 1, 1987
Creator: Mougey, Jean
Partner: UNT Libraries Government Documents Department

Controller strategy for a 6 DOF piezoelectric translation stage

Description: A controller for the third generation, 6 degree-of-freedom (DOF) piezoelectric translation stage shown in Figure 1 is presented. This was tested by monitoring all six coordinate motions using an orthogonal array of six, high-resolution capacitance gages. The full 6 DOF matrix transformations and controller block diagrams for this system have been measured and the system operated under closed loop control. Results of early experiments to determine the 21 open loop response functions as well as preliminary results showing the closed loop response for the 3 linear translations are presented in this abstract. The ultimate goal of this project is to incorporate this 6 DOF stage within a long range X-Y scanning system for nanometer pick-and-place capability over an area of 50 x 50 mm. The control strategy and early results from this system will be presented.
Date: March 22, 2006
Creator: Buice, E S; Yang, H; Smith, S T; Hocken, R J; Trumper, D L; Otten, D et al.
Partner: UNT Libraries Government Documents Department

Damage detection using frequency domain ARX models and extreme value statistics

Description: Structural health monitoring (SHM) is fast becoming a field of great importance as engineers seek for new ways to ensure the safety of structures throughout their designed lifetime. Current methods for analyzing the dynamic response of structures often use standard frequency response functions to model linear system input/output relationships. However, these functions do not account for the nonlinear response of a system, which damage often introduces. In this study, an auto-regressive model with exogenous inputs (ARX) in the frequency domain is used to extract damage sensitive features, explicitly considering the nonlinear effect in the frequency domain. Furthermore, because of the non-Gaussian nature of the extracted features, extreme value statistics (EVS) is employed to develop a robust damage classifier. The applicability of the ARX model combined with EVS to nonlinear damage detection is demonstrated using vibration data obtained from a laboratory experiment of a three-story building model.
Date: January 1, 2002
Creator: Fasel, T. R. (Timothy R.); Sohn, H. (Hoon) & Farrar, C. R. (Charles R.)
Partner: UNT Libraries Government Documents Department

Some remarks on antenna response in a reverberation chamber

Description: The simple formula, {l_angle}P{sub r}{r_angle}=(E{sub o}{sup 2}/{eta})({lambda}{sup 2}/8{pi}), for the received power of an antenna with a matched load in an over-moded cavity actually holds for an antenna of any shape and size. This can be seen from the close connection between the correlation tensor of the cavity field at two different points and the imaginary part of the free-space dyadic Green's function.
Date: March 15, 2000
Creator: WARNE,LARRY K. & LEE,K.S.H.
Partner: UNT Libraries Government Documents Department

Vibration Testing - Reviewing the State of the Art

Description: Vibration testing has advanced significantly over the past several decades. Comparatively speaking, enormous volumes of acceleration data are now available for virtually every vibration test. This data is readily compressed into frequency response functions and modal models. The modal models are compared with corresponding analytical models. Model updating techniques are used to adjust analytical model parameters to minimize the differences between model and test frequencies and mode shapes. These are very positive developments. Model and testing limitations lie in areas other than the direct recording and translation of acceleration data to modal models. Two major limitations of models are the inability to model damping and the limited degree to which nonlinear behavior is incorporated into model construction and model validation. Much more thorough understanding of damping mechanisms in real structures is required. Currently we know enough to bound the range of damping values for some typical structures. A much more thorough understanding of mechanical joints is required to accurately model structural joints. Some studies now underway offer a beginning to such understanding.
Date: June 23, 1999
Creator: Hunter, N. F.
Partner: UNT Libraries Government Documents Department

Statistical Properties of Antenna Impedance in an Electrically Large Cavity

Description: This paper presents models and measurements of antenna input impedance in resonant cavities at high frequencies.The behavior of input impedance is useful in determining the transmission and reception characteristics of an antenna (as well as the transmission characteristics of certain apertures). Results are presented for both the case where the cavity is undermoded (modes with separate and discrete spectra) as well as the over moded case (modes with overlapping spectra). A modal series is constructed and analyzed to determine the impedance statistical distribution. Both electrically small as well as electrically longer resonant and wall mounted antennas are analyzed. Measurements in a large mode stirred chamber cavity are compared with calculations. Finally a method based on power arguments is given, yielding simple formulas for the impedance distribution.
Date: December 13, 2000
Creator: WARNE,LARRY K.; LEE,KELVIN S.H.; HUDSON,H. GERALD; JOHNSON,WILLIAM A.; JORGENSON,ROY E. & STRONACH,STEPHEN L.
Partner: UNT Libraries Government Documents Department

A NOVEL STATISTICAL BASED APPROACH TO NON-LINEAR MODEL UPDATING USING RESPONSE FEATURES

Description: This research presents a new method to improve analytical model fidelity for non-linear systems. The approach investigates several mechanisms to assist the analyst in updating an analytical model based on experimental data and statistical analysis of parameter effects. The first is a new approach at data reduction called feature extraction. This is an expansion of the ''classic'' update metrics to include specific phenomena or characters of the response that are critical to model application. This is an extension of the familiar linear updating paradigm of utilizing the eigen-parameters or frequency response functions (FRFs) to include such devices as peak acceleration, time of arrival or standard deviation of model error. The next expansion of the updating process is the inclusion of statistical based parameter analysis to quantify the effects of uncertain or significant effect parameters in the construction of a meta-model. This provides indicators of the statistical variation associated with parameters as well as confidence intervals on the coefficients of the resulting meta-model. Also included in this method is the investigation of linear parameter effect screening using a partial factorial variable array for simulation. This is intended to aid the analyst in eliminating from the investigation the parameters that do not have a significant variation effect on the feature metric. Finally an investigation of the model to replicate the measured response variation is examined.
Date: March 1, 2001
Creator: SCHULTZ, J. & AL, ET
Partner: UNT Libraries Government Documents Department

Applications of the Automated SMAC Modal Parameter Extraction Package

Description: An algorithm known as SMAC (Synthesize Modes And Correlate), based on principles of modal filtering, has been in development for a few years. The new capabilities of the automated version are demonstrated on test data from a complex shell/payload system. Examples of extractions from impact and shaker data are shown. The automated algorithm extracts 30 to 50 modes in the bandwidth from each column of the frequency response function matrix. Examples of the synthesized Mode Indicator Functions (MIFs) compared with the actual MIFs show the accuracy of the technique. A data set for one input and 170 accelerometer outputs can typically be reduced in an hour. Application to a test with some complex modes is also demonstrated.
Date: October 29, 1999
Creator: MAYES,RANDALL L.; DORRELL,LARRY R. & KLENKE,SCOTT E.
Partner: UNT Libraries Government Documents Department

On the long-time behavior of ferroelectric systems

Description: In this note we investigate a new model for the behavior of ferroelectric materials. This model is analogous to one used in [1] to describe the dynamics of elastic materials which exhibit phase changes.
Date: July 16, 2003
Creator: Greenberg, J. M.; MacCamy, R. C. & Coffman, C. V.
Partner: UNT Libraries Government Documents Department

Preliminary report on operational guidelines developed for use in emergency preparedness and response to a radiological dispersal device incident.

Description: This report presents preliminary operational guidelines and supporting work products developed through the interagency Operational Guidelines Task Group (OGT). The report consolidates preliminary operational guidelines, all ancillary work products, and a companion software tool that facilitates their implementation into one reference source document. The report is intended for interim use and comment and provides the foundation for fostering future reviews of the operational guidelines and their implementation within emergency preparedness and response initiatives in the event of a radiological dispersal device (RDD) incident. The report principally focuses on the technical derivation and presentation of the operational guidelines. End-user guidance providing more details on how to apply these operational guidelines within planning and response settings is being considered and developed elsewhere. The preliminary operational guidelines are categorized into seven groups on the basis of their intended application within early, intermediate, and long-term recovery phases of emergency response. We anticipate that these operational guidelines will be updated and refined by interested government agencies in response to comments and lessons learned from their review, consideration, and trial application. This review, comment, and trial application process will facilitate the selection of a final set of operational guidelines that may be more or less inclusive of the preliminary operational guidelines presented in this report. These and updated versions of the operational guidelines will be made available through the OGT public Web site (http://ogcms.energy.gov) as they become finalized for public distribution and comment.
Date: December 15, 2006
Creator: Yu, C.; Cheng, J.-J.; Kamboj, S.; Domotor, S.; Wallo, A.; Division, Environmental Science et al.
Partner: UNT Libraries Government Documents Department

HLW Canister and Can-In-Canister Drop Calculation

Description: The purpose of this calculation is to evaluate the structural response of the standard high-level waste (HLW) canister and the HLW canister containing the cans of immobilized plutonium (''can-in-canister'' throughout this document) to the drop event during the handling operation. The objective of the calculation is to provide the structure parameter information to support the canister design and the waste handling facility design. Finite element solution is performed using the commercially available ANSYS Version (V) 5.4 finite element code. Two-dimensional (2-D) axisymmetric and three-dimensional (3-D) finite element representations for the standard HLW canister and the can-in-canister are developed and analyzed using the dynamic solver.
Date: September 15, 1999
Creator: Marr, H.
Partner: UNT Libraries Government Documents Department

Vibration response for a multilayer cylinder

Description: Consider a circular cylinder composed of N concentric layers of materials. Each layer is characterized by its material density {rho}{sub n}, and elastic moduli {lambda}{sub n} and {mu}{sub n} (n = 1,...,N). The interfaces between layers are specified by the radii R{sub 0}, R{sub 1},..., R{sub n}, with R{sub 0} the inner surface and R{sub N} the outer surface of the cylinder.
Date: February 28, 2007
Creator: Chambers, D H
Partner: UNT Libraries Government Documents Department

Waste Package Lifting Calculation

Description: The objective of this calculation is to evaluate the structural response of the waste package during the horizontal and vertical lifting operations in order to support the waste package lifting feature design. The scope of this calculation includes the evaluation of the 21 PWR UCF (pressurized water reactor uncanistered fuel) waste package, naval waste package, 5 DHLW/DOE SNF (defense high-level waste/Department of Energy spent nuclear fuel)--short waste package, and 44 BWR (boiling water reactor) UCF waste package. Procedure AP-3.12Q, Revision 0, ICN 0, calculations, is used to develop and document this calculation.
Date: May 11, 2000
Creator: Marr, H.
Partner: UNT Libraries Government Documents Department

On the response of rubbers at high strain rates.

Description: In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strain and particle velocity in the rubber strips. Analysis of the response through the theory of finite waves and quantitative matching between the experimental observations and analytical predictions was used to determine an appropriate instantaneous elastic response for the rubbers. This analysis also yields the tensile shock adiabat for rubber. Dispersive waves as well as shock waves are also observed in free-retraction experiments; these are used to quantify hysteretic effects in rubber.
Date: February 1, 2010
Creator: Niemczura, Johnathan Greenberg (University of Texas-Austin)
Partner: UNT Libraries Government Documents Department

Benchmark Calculation Of Inclusive Responses In The Four-Body Nuclear System

Description: This paper reports on a recent benchmark calculation in the four-nucleon system, aimed at investigating the reliability of the no-core shell model (NCSM) approach to the description of inclusive response functions via the Lorentz integral transform (LIT) method.
Date: September 27, 2006
Creator: Quaglioni, S; Stetcu, I; Bacca, S; Barrett, B R; Johnson, C W; Navratil, P et al.
Partner: UNT Libraries Government Documents Department

Gamma Ray Multiplicity of 252Cf Spontaneous Fission using LiBerACE

Description: We are studying the gamma ray and neutron multiplicity of various fission processes, beginning with the spontaneous fission of {sup 252}Cf, for a variety of basic and applied science purposes. The Livermore-Berkeley Array for Collaborative Experiments (LiBerACE) consists of six high-purity germanium Clover detectors (HPGe) each enclosed by an array of 16 bismuth-germanate (BGO) detectors. These detectors were arranged in a cubic pattern around a 1 {micro}Ci {sup 252}Cf source to attempt to cover as much solid angle of gamma ray emission as possible with a high level of segmentation. The single-gamma detector response function is determined at several energies by tagging in a HPGe detector on the photopeak of one of two gamma rays in two-gamma ray calibration sources and observing the multiplicity of the remainder of the array. Summing these single-gamma responses in groups yields the response function of the array to higher multiplicity events, which are convolved with multiplicity distributions from theoretical models and compared to the measured results to test the models validity.
Date: January 15, 2008
Creator: Bleuel, D L; Bernstein, L A; Burke, J T; Heffner, M D; Norman, E B; Scielzo, N D et al.
Partner: UNT Libraries Government Documents Department

COMPARISONS OF CODED APERTURE IMAGING USING VARIOUS APERTURES AND DECODING METHODS

Description: The utility of coded aperture imaging of radioisotope distributions in Nuclear Medicine is in its ability to give depth information about a three dimensional source. We have calculated imaging with Fresnel zone plate and multiple pinhole apertures to produce coded shadows and reconstruction of these shadows using correlation, Fresnel diffraction, and Fourier transform deconvolution. Comparisons of the coded apertures and decoding methods are made by evaluating their point response functions both for in-focus and out-of-focus image planes. Background averages and standard deviations were calculated. In some cases, background subtraction was made using combinations of two complementary apertures. Results using deconvolution reconstruction for finite numbers of events are also given.
Date: July 1, 1976
Creator: Chang, L.-T.; Macdonald, B. & Perez-Mendez, V.
Partner: UNT Libraries Government Documents Department

Benchmark Calculation of Inclusive Electromagnetic Responses in the Four-Body Nuclear System

Description: Both the no-core shell model and the effective interaction hyperspherical harmonic approaches are applied to the calculation of different response functions to external electromagnetic probes, using the Lorentz integral transform method. The test is performed on the four-body nuclear system, within a simple potential model. The quality of the agreement in the various cases is discussed, together with the perspectives for rigorous ab initio calculations of cross sections of heavier nuclei.
Date: May 9, 2006
Creator: Stetcu, I; Quaglioni, S; Bacca, S; Barrett, B R; Johnson, C W; Navratil, P et al.
Partner: UNT Libraries Government Documents Department

LONGITUDINAL MEASUREMENTS AND SIMULATIONS OF STRETCHED BUNCHES IN THE NSLS VUV RING.

Description: Certain longitudinal instabilities in the stretched bunches of the National Synchrotron Light Source Vacuum Ultra-Violet ring are described and simulated using a code for the integration of the Vlasov-Fokker-Planck equation (these proceedings). Results for the microwave instability driven by broadband impedance, instability driven by high-Q radio-frequency modes, and response functions in stretched bunches, are compared with measurements from the ring.
Date: June 18, 2001
Creator: TOWNE,N.
Partner: UNT Libraries Government Documents Department

Final State Interactions and Relativistic Effects in the Quasielastic (E,E') Reaction

Description: The longitudinal and transverse response functions for the inclusive quasielastic (e,e') reaction are analyzed in detail.A microscopic theoretical framework for the many-body reaction provides a clear conceptual (nonrelativistic) basis for treating final state interactions and goes far beyond simple plane wave or Hermitean potential models.The many-body physics of inelastic final state channels as described by optical and multiple scattering theories is properly included by incorporating a full complex optical potential.Explicit nonrelativistic and relativistic momentum-space calculations quantitatively demonstrate the importance of such a treatment of final state interactions for both the transverse and longitudinal response.Nonrelativistic calculations are performed using final state interactions based on phenomenology, local density models and microscopic multiple scattering theory.Relativistic calculations span a similar range of models and employ Dirac bound state wave f
Date: January 1, 1988
Creator: Picklesimer, Alan; Chinn, Clayton & Van Orden, Jay
Partner: UNT Libraries Government Documents Department