Study of Ion Acoustic Wave Damping through Green's Functions
DEFF Research Database (Denmark)
Hsuan, H.C.S.; Jensen, Vagn Orla
1973-01-01
Green's function analyses of ion acoustic waves in streaming plasmas show that, in general, the waves damp algebraically rather than exponentially with distance from exciter.......Green's function analyses of ion acoustic waves in streaming plasmas show that, in general, the waves damp algebraically rather than exponentially with distance from exciter....
Chen, D
The $\\textbf{DA}$rk $\\textbf{M}$atter $\\textbf{P}$article $\\textbf{E}$xplorer (DAMPE) experiment is a high-energy astroparticle physics satellite mission to search for Dark Matter signatures in space, study the cosmic ray spectrum and composition up to 100 TeV, and perform high-energy gamma astronomy. The launch is planned for end 2015, initially for 3 years, to compliment existing space missions FERMI, AMS and CALET.
Cost damping and functional form in transport models
DEFF Research Database (Denmark)
Rich, Jeppe; Mabit, Stefan Lindhard
2016-01-01
out to be an important guidance as the damping rate largely dictates which link functions are appropriate for the data. Thirdly, inspired by the Box–Cox function, we propose alternative linear-in-parameter link functions, some of which are based on interpolation of approximate Box–Cox end points...
Waveform inversion with exponential damping using a deconvolution-based objective function
Choi, Yun Seok
2016-09-06
The lack of low frequency components in seismic data usually leads full waveform inversion into the local minima of its objective function. An exponential damping of the data, on the other hand, generates artificial low frequencies, which can be used to admit long wavelength updates for waveform inversion. Another feature of exponential damping is that the energy of each trace also exponentially decreases with source-receiver offset, where the leastsquare misfit function does not work well. Thus, we propose a deconvolution-based objective function for waveform inversion with an exponential damping. Since the deconvolution filter includes a division process, it can properly address the unbalanced energy levels of the individual traces of the damped wavefield. Numerical examples demonstrate that our proposed FWI based on the deconvolution filter can generate a convergent long wavelength structure from the artificial low frequency components coming from an exponential damping.
Islam, Naz Niamul; Hannan, M A; Shareef, Hussain; Mohamed, Azah; Salam, M A
2014-01-01
Power oscillation damping controller is designed in linearized model with heuristic optimization techniques. Selection of the objective function is very crucial for damping controller design by optimization algorithms. In this research, comparative analysis has been carried out to evaluate the effectiveness of popular objective functions used in power system oscillation damping. Two-stage lead-lag damping controller by means of power system stabilizers is optimized using differential search algorithm for different objective functions. Linearized model simulations are performed to compare the dominant mode's performance and then the nonlinear model is continued to evaluate the damping performance over power system oscillations. All the simulations are conducted in two-area four-machine power system to bring a detailed analysis. Investigated results proved that multiobjective D-shaped function is an effective objective function in terms of moving unstable and lightly damped electromechanical modes into stable region. Thus, D-shape function ultimately improves overall system damping and concurrently enhances power system reliability.
Waveform inversion with exponential damping using a deconvolution-based objective function
Choi, Yun Seok; Alkhalifah, Tariq Ali
2016-01-01
The lack of low frequency components in seismic data usually leads full waveform inversion into the local minima of its objective function. An exponential damping of the data, on the other hand, generates artificial low frequencies, which can
ENHANCEMENT OF DAMPING PERFORMANCE OF POLYMERS BY FUNCTIONAL SMALL MOLECULES
Institute of Scientific and Technical Information of China (English)
Chi-fei Wu; Saburo Akiyama
2002-01-01
The addition effects of organic small molecular substances N,N'-dicyclohexyl-benzothiazyl-2-sulfenamide (DZ) and 3,9-bis{ 1, 1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8, 10-tetraoxaspiro[5,5]-undecane (AO-80) on the dynamic mechanical properties of chlorinated polyethylene (CPE), chlorinated polypropylene (CPP), acrylate rubber (ACM) and their blends were investigated. In the case of compatible systems such as CPE/DZ and ACM/AO-80, the height of the loss tangent (tanδ) peak of a matrix polymer (CPE or ACM) increases, and its peak position shifts to a higher temperature with the addition of DZ or AO-80. By contrast, for incompatible CPE/AO-80, a novel transition appeared above the glass transition temperature of CPE. This additional transition was assigned to dissociation of the intermolecular hydrogen bond between the α-hydrogen of CPE and the hydroxyl groups of AO-80 within the AO-80-rich domain. This will provide a new concept for developing damping material. However, the minimum value between two tanδ peaks is lower. It was found that the temperature dependence of tanδ could be improved by adding chlorinated paraffin (CP) or ACM to CPE/AO-80. In addition, another ternary system of ACM/CPP with more AO-80 was found to be a very good self-adhesive damping material because of the appearance of a novel transition due to an interfacial layer of ACM/CPP.
HI column density distribution function at z=0 : Connection to damped Ly alpha statistics
Zwaan, Martin; Verheijen, MAW; Briggs, FH
We present a measurement of the HI column density distribution function f(N-HI) at the present epoch for column densities > 10(20) cm(-2). These high column densities compare to those measured in damped Ly alpha lines seen in absorption against background quasars. Although observationally rare, it
On a total function which overtakes all total recursive functions
da Costa, N. C. A.; Doria, F. A.
2001-01-01
This paper discusses a function that is frequently presented as a simile or look-alike of the so-called ``counterexample function to P=NP,'' that is, the function that collects all first instances of a problem in NP where a poly machine incorrectly `guesses' about the instance. We state and give in full detail a crucial result on the computation of Goedel numbers for some families of poly machines.
Lee, Myoung-Jae; Jung, Young-Dae
2018-04-01
The influence of Landau damping on the spin-oriented collisional asymmetry is investigated in electron-hole semiconductor plasmas. The analytical expressions of the spin-singlet and the spin-triplet scattering amplitudes as well as the spin-oriented asymmetry Sherman function are obtained as functions of the scattering angle, the Landau parameter, the effective Debye length, and the collision energy. It is found that the Landau damping effect enhances the spin-singlet and spin-triplet scattering amplitudes in the forward and back scattering domains, respectively. It is also found that the Sherman function increases with an increase in the Landau parameter. In addition, the spin-singlet scattering process is found to be dominant rather than the spin-triplet scattering process in the high collision energy domain.
MD 1407 - Landau Damping: Beam Transfer Functions and diffusion mechanisms
Tambasco, Claudia; Boccardi, Andrea; Buffat, Xavier; Gasior, Marek; Lefevre, Thibaut; Levens, Tom; Pojer, Mirko; Salvachua Ferrando, Belen Maria; Solfaroli Camillocci, Matteo; Pieloni, Tatiana; Crouch, Matthew Paul; CERN. Geneva. ATS Department
2017-01-01
In the 2012, 2015 and 2016 run several instabilities were developing at flat-top, during and at the end of the betatron squeeze where beam-beam interactions are present. The tune spread in the beams is therefore modified by the beam-beam long-range interactions and by other sources of spread. Studies of the stability area computed by evaluating the dispersion integral for different tune spreads couldn’t explain the observed instabilities during the squeeze and stable beams. The size of the stability area given by the computed dispersion integral depends on the transverse tune spread but its shape is defined by the particle distribution in the beams. Therefore any change of the particle distribution can lead to a deterioration of the Landau stability area. The Beam Transfer Functions (BTF) are direct measurements of the Stability Diagrams (SD). They are sensitive to particle distributions and contain information about the transverse tune spread in the beams. In this note are summarized the results of the BTF...
Green’s function theory of ferromagnetic resonance in magnetic superlattices with damping
International Nuclear Information System (INIS)
Qiu, R.K.; Guo, F.F.; Zhang, Z.D.
2016-01-01
We explore a quantum Green’s-function method to study the resonance absorption of magnetic materials. The relationship between the resonance magnon (spin wave) density and the resonance frequency of a superlattice consisting of two magnetic layers with damping and antiferromagnetic interlayer exchange coupling is studied. The effects of temperature, interlayer coupling, anisotropy, external magnetic field and damping on the the resonance frequency and resonance magnon density are investigated. The resonance excitation probability for a magnon is proportional to the resonance magnon density. In the classic methods, the imaginary part of magnetic permeability represents the resonance absorption in magnetic materials. In the quantum approach, the resonance magnon density can be used to estimate the strength of the resonance absorption. In the present work, a quantum approach is developed to study resonance absorption of magnetic materials and the results show the method to obtain a magnetic multilayered materials with both high resonance frequency and high resonance absorption.
Green’s function theory of ferromagnetic resonance in magnetic superlattices with damping
Energy Technology Data Exchange (ETDEWEB)
Qiu, R.K., E-mail: rkqiu@163.com [Shenyang University of Technology, Shenyang 110870 (China); Guo, F.F. [Shenyang University of Technology, Shenyang 110870 (China); Zhang, Z.D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)
2016-02-01
We explore a quantum Green’s-function method to study the resonance absorption of magnetic materials. The relationship between the resonance magnon (spin wave) density and the resonance frequency of a superlattice consisting of two magnetic layers with damping and antiferromagnetic interlayer exchange coupling is studied. The effects of temperature, interlayer coupling, anisotropy, external magnetic field and damping on the the resonance frequency and resonance magnon density are investigated. The resonance excitation probability for a magnon is proportional to the resonance magnon density. In the classic methods, the imaginary part of magnetic permeability represents the resonance absorption in magnetic materials. In the quantum approach, the resonance magnon density can be used to estimate the strength of the resonance absorption. In the present work, a quantum approach is developed to study resonance absorption of magnetic materials and the results show the method to obtain a magnetic multilayered materials with both high resonance frequency and high resonance absorption.
Pole-placement Predictive Functional Control for under-damped systems with real numbers algebra.
Zabet, K; Rossiter, J A; Haber, R; Abdullah, M
2017-11-01
This paper presents the new algorithm of PP-PFC (Pole-placement Predictive Functional Control) for stable, linear under-damped higher-order processes. It is shown that while conventional PFC aims to get first-order exponential behavior, this is not always straightforward with significant under-damped modes and hence a pole-placement PFC algorithm is proposed which can be tuned more precisely to achieve the desired dynamics, but exploits complex number algebra and linear combinations in order to deliver guarantees of stability and performance. Nevertheless, practical implementation is easier by avoiding complex number algebra and hence a modified formulation of the PP-PFC algorithm is also presented which utilises just real numbers while retaining the key attributes of simple algebra, coding and tuning. The potential advantages are demonstrated with numerical examples and real-time control of a laboratory plant. Copyright © 2017 ISA. All rights reserved.
Asiri, Sharefa M.; Laleg-Kirati, Taous-Meriem
2017-01-01
In this paper, a method based on modulating functions is proposed to estimate the Cerebral Blood Flow (CBF). The problem is written in an input estimation problem for a damped wave equation which is used to model the spatiotemporal variations
Totally optimal decision trees for Boolean functions
Chikalov, Igor; Hussain, Shahid; Moshkov, Mikhail
2016-01-01
We study decision trees which are totally optimal relative to different sets of complexity parameters for Boolean functions. A totally optimal tree is an optimal tree relative to each parameter from the set simultaneously. We consider the parameters
Role of radiation damping in the impedance function approach to soil-structure interaction analysis
International Nuclear Information System (INIS)
1980-05-01
This report was prepared at the request of the Lawrence Livermore Laboratory (LLL) to provide background information for analyzing soil-structure interaction by the frequency-independent impedance function approach. LLL is conducting such analyses as part of its seismic review of selected operating plants under the Systematic Evaluation Program for the US Nuclear Regulatory Commission. The analytical background and basic assumptionsof the impedance function theory are briefly reviewed, and the role of radiation damping in soil-structure interaction analysis is discussed. The validity of modeling soil-structure interaction by using frequency-independent functions is evaluated based on data from several field tests. Finally, the recommended procedures for performing soil-structure interaction analyses are discussed with emphasis on the modal superposition method
Choi, Yun Seok
2017-11-15
Full waveform inversion (FWI) suffers from the cycle-skipping problem when the available frequency-band of data is not low enough. We apply an exponential damping to the data to generate artificial low frequencies, which helps FWI avoid cycle skipping. In this case, the least-square misfit function does not properly deal with the exponentially damped wavefield in FWI, because the amplitude of traces decays almost exponentially with increasing offset in a damped wavefield. Thus, we use a deconvolution-based objective function for FWI of the exponentially damped wavefield. The deconvolution filter includes inherently a normalization between the modeled and observed data, thus it can address the unbalanced amplitude of a damped wavefield. We, specifically, normalize the modeled data with the observed data in the frequency-domain to estimate the deconvolution filter and selectively choose a frequency-band for normalization that mainly includes the artificial low frequencies. We calculate the gradient of the objective function using the adjoint-state method. The synthetic and benchmark data examples show that our FWI algorithm generates a convergent long wavelength structure without low frequency information in the recorded data.
Choi, Yun Seok; Alkhalifah, Tariq Ali
2017-01-01
Full waveform inversion (FWI) suffers from the cycle-skipping problem when the available frequency-band of data is not low enough. We apply an exponential damping to the data to generate artificial low frequencies, which helps FWI avoid cycle skipping. In this case, the least-square misfit function does not properly deal with the exponentially damped wavefield in FWI, because the amplitude of traces decays almost exponentially with increasing offset in a damped wavefield. Thus, we use a deconvolution-based objective function for FWI of the exponentially damped wavefield. The deconvolution filter includes inherently a normalization between the modeled and observed data, thus it can address the unbalanced amplitude of a damped wavefield. We, specifically, normalize the modeled data with the observed data in the frequency-domain to estimate the deconvolution filter and selectively choose a frequency-band for normalization that mainly includes the artificial low frequencies. We calculate the gradient of the objective function using the adjoint-state method. The synthetic and benchmark data examples show that our FWI algorithm generates a convergent long wavelength structure without low frequency information in the recorded data.
Motion of a damped oscillating sphere as a function of the medium viscosity
International Nuclear Information System (INIS)
Mendoza-Arenas, J J; Perico, E L D; Fajardo, F
2010-01-01
In this paper, an experimental setup for undergraduate courses to study the damped harmonic motion of a sphere inside a fluid as a function of the medium viscosity is presented. To observe the dependence of the oscillation of the sphere on the medium viscosity, different concentrations of glycerin in water were used. The sphere is suspended on the end of a spring and its displacement is indirectly obtained using a force sensor. To describe the sphere motion, a drag force different from that given by Stokes' law is used. Our experimental results fit satisfactorily when semiempirical coefficients are introduced in the model. The frequency and relaxation time of the sphere oscillations diminish as the concentration of glycerin increases. Boundary effects due to the fluid container size are studied. We found that when the container size decreases the oscillations decay more rapidly due to a greater resistance to the motion of the sphere.
Totally optimal decision trees for Boolean functions
Chikalov, Igor
2016-07-28
We study decision trees which are totally optimal relative to different sets of complexity parameters for Boolean functions. A totally optimal tree is an optimal tree relative to each parameter from the set simultaneously. We consider the parameters characterizing both time (in the worst- and average-case) and space complexity of decision trees, i.e., depth, total path length (average depth), and number of nodes. We have created tools based on extensions of dynamic programming to study totally optimal trees. These tools are applicable to both exact and approximate decision trees, and allow us to make multi-stage optimization of decision trees relative to different parameters and to count the number of optimal trees. Based on the experimental results we have formulated the following hypotheses (and subsequently proved): for almost all Boolean functions there exist totally optimal decision trees (i) relative to the depth and number of nodes, and (ii) relative to the depth and average depth.
Structural damping values as a function of dynamic response stress and deformation levels
International Nuclear Information System (INIS)
Stevenson, J.D.
1980-01-01
Damping as it is normally defined is the means by which the response motion of a structural system is reduced as the result of energy losses. However, as used in the context of nuclear plant design, the effects of changes in structural stiffness, geometry, support configuration, and modulus of elasticity are also usually lumped under the general heading of damping in current design methods. For convenience in structural design, damping in usually assumed as viscous in nature and in recognition of its use in modal response spectrum dynamic analysis is normally expressed as a percent of critical. In general, it should be understood that damping as used in design or analysis of nuclear plants is an experimentally determined factor which is used to make the results of linear elasticity analysis of dynamic systems agree reasonably well with observed experimental results. In this paper, damping data existing in the open literature applicable to nuclear power plant structures and equipment is summarized and statistically analyzed. Results of this analysis are used to develop damping trend curves which predict applicable damping values to be used in design at various levels of stress or deformation. (orig.)
Directory of Open Access Journals (Sweden)
Pichai Aree
2005-07-01
Full Text Available The transfer-function block-diagram model of single-machine infinite-bus power system has been a popular analytical tool amongst power engineers for explaining and assessing synchronous generator dynamic behaviors. In previous studies, the effects of local load together with damper circuit on generator damping have not yet been addressed because neither of them was integrated into this model. Since the model only accounts for the generator main field circuit, it may not always yield a realistic damping assessment due to lack of damper circuit representation. This paper presents an extended transfer-function block-diagram model, which includes one of the q-axis damper circuits as well as local load. This allows a more realistic investigation of the local load effect on the generator damping. The extended model is applied to assess thegenerator dynamic performance. The results show that the damping power components mostly derived from the q-axis damper and the field circuits can be improved according to the local load. The frequency response method is employed to carry out the fundamental analysis.
Fay, Temple H.
2012-01-01
Quadratic friction involves a discontinuous damping term in equations of motion in order that the frictional force always opposes the direction of the motion. Perhaps for this reason this topic is usually omitted from beginning texts in differential equations and physics. However, quadratic damping is more realistic than viscous damping in many…
Total Variation Depth for Functional Data
Huang, Huang
2016-11-15
There has been extensive work on data depth-based methods for robust multivariate data analysis. Recent developments have moved to infinite-dimensional objects such as functional data. In this work, we propose a new notion of depth, the total variation depth, for functional data. As a measure of depth, its properties are studied theoretically, and the associated outlier detection performance is investigated through simulations. Compared to magnitude outliers, shape outliers are often masked among the rest of samples and harder to identify. We show that the proposed total variation depth has many desirable features and is well suited for outlier detection. In particular, we propose to decompose the total variation depth into two components that are associated with shape and magnitude outlyingness, respectively. This decomposition allows us to develop an effective procedure for outlier detection and useful visualization tools, while naturally accounting for the correlation in functional data. Finally, the proposed methodology is demonstrated using real datasets of curves, images, and video frames.
International Nuclear Information System (INIS)
Ware, A.G.
1985-01-01
Studies are being conducted at the Idaho National Engineering Laboratory to determine whether an increase in the damping values used in seismic structural analyses of nuclear piping systems is justified. Increasing the allowable damping would allow fewer piping supports which could lead to safer, more reliable, and less costly piping systems. Test data from availble literature were examined to determine the important parameters contributing to piping system damping, and each was investigated in separate-effects tests. From the combined results a world pipe damping data bank was established and multiple regression analyses performed to assess the relative contributions of the various parameters. The program is being extended to determine damping applicable to higher frequency (33 to 100 Hz) fluid-induced loadings. The goals of the program are to establish a methodology for predicting piping system damping and to recommend revised guidelines for the damping values to be included in analyses
Asiri, Sharefa M.
2017-10-19
In this paper, a method based on modulating functions is proposed to estimate the Cerebral Blood Flow (CBF). The problem is written in an input estimation problem for a damped wave equation which is used to model the spatiotemporal variations of blood mass density. The method is described and its performance is assessed through some numerical simulations. The robustness of the method in presence of noise is also studied.
Directory of Open Access Journals (Sweden)
M. Mallika Arjunan
2014-01-01
Full Text Available In this paper, we investigate the existence and controllability of mild solutions for a damped second order impulsive functional differential equation with state-dependent delay in Banach spaces. The results are obtained by using Sadovskii's fixed point theorem combined with the theories of a strongly continuous cosine family of bounded linear operators. Finally, an example is provided to illustrate the main results.
International Nuclear Information System (INIS)
Rees, John; Chao, Alexander
2008-01-01
Landau damping, as the term is used in accelerator science, is a physical process in which an ensemble of harmonic oscillators--an accelerator beam, for example--that would otherwise be unstable is stabilized by a spread in the natural frequencies of the oscillators. This is a study of the most basic aspects of that process. It has two main goals: to gain a deeper insight into the mechanism of Landau damping and to find the coherent motion of the ensemble and thus the dependence of the total damping rate on the frequency spread
Fay, Temple H.
2012-01-01
Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…
Damping layout optimization for ship's cabin noise reduction based on statistical energy analysis
Directory of Open Access Journals (Sweden)
WU Weiguo
2017-08-01
Full Text Available An optimization analysis study concerning the damping control of ship's cabin noise was carried out in order to improve the effect and reduce the weight of damping. Based on the Statistical Energy Analysis (SEA method, a theoretical deduction and numerical analysis of the first-order sensitivity analysis of the A-weighted sound pressure level concerning the damping loss factor of the subsystem were carried out. On this basis, a mathematical optimization model was proposed and an optimization program developed. Next, the secondary development of VA One software was implemented through the use of MATLAB, while the cabin noise damping control layout optimization system was established. Finally, the optimization model of the ship was constructed and numerical experiments of damping control optimization conducted. The damping installation region was divided into five parts with different damping thicknesses. The total weight of damping was set as an objective function and the A-weighted sound pressure level of the target cabin was set as a constraint condition. The best damping thickness was obtained through the optimization program, and the total damping weight was reduced by 60.4%. The results show that the damping noise reduction effect of unit weight is significantly improved through the optimization method. This research successfully solves the installation position and thickness selection problems in the acoustic design of damping control, providing a reliable analysis method and guidance for the design.
Energy Technology Data Exchange (ETDEWEB)
Mendoza Herrera, Luis J.; Arboleda, David Muñetón [Centro de Investigaciones Ópticas (CIOp), (CONICET La Plata-CIC) (Argentina); Schinca, Daniel C.; Scaffardi, Lucía B., E-mail: lucias@ciop.unlp.edu.ar [Centro de Investigaciones Ópticas (CIOp), (CONICET La Plata-CIC) (Argentina); Departamento de Ciencias Básicas, Facultad de Ingeniería, UNLP (Argentina)
2014-12-21
This paper develops a novel method for simultaneously determining the plasma frequency ω{sub P} and the damping constant γ{sub free} in the bulk damped oscillator Drude model, based on experimentally measured real and imaginary parts of the metal refractive index in the IR wavelength range, lifting the usual approximation that restricts frequency values to the UV-deep UV region. Our method was applied to gold, silver, and copper, improving the relative uncertainties in the final values for ω{sub p} (0.5%–1.6%) and for γ{sub free} (3%–8%), which are smaller than those reported in the literature. These small uncertainties in ω{sub p} and γ{sub free} determination yield a much better fit of the experimental complex dielectric function. For the case of nanoparticles (Nps), a series expansion of the Drude expression (which includes ω{sub p} and γ{sub free} determined using our method) enables size-dependent dielectric function to be written as the sum of three terms: the experimental bulk dielectric function plus two size corrective terms, one for free electron, and the other for bound-electron contributions. Finally, size distribution of nanometric and subnanometric gold Nps in colloidal suspension was determined through fitting its experimental optical extinction spectrum using Mie theory based on the previously determined dielectric function. Results are compared with size histogram obtained from Transmission Electron Microscopy (TEM)
The damped wave equation with unbounded damping
Freitas, Pedro; Siegl, Petr; Tretter, Christiane
2018-06-01
We analyze new phenomena arising in linear damped wave equations on unbounded domains when the damping is allowed to become unbounded at infinity. We prove the generation of a contraction semigroup, study the relation between the spectra of the semigroup generator and the associated quadratic operator function, the convergence of non-real eigenvalues in the asymptotic regime of diverging damping on a subdomain, and we investigate the appearance of essential spectrum on the negative real axis. We further show that the presence of the latter prevents exponential estimates for the semigroup and turns out to be a robust effect that cannot be easily canceled by adding a positive potential. These analytic results are illustrated by examples.
Total Variation Depth for Functional Data
Huang, Huang; Sun, Ying
2016-01-01
that are associated with shape and magnitude outlyingness, respectively. This decomposition allows us to develop an effective procedure for outlier detection and useful visualization tools, while naturally accounting for the correlation in functional data. Finally
Production Function Geometry with "Knightian" Total Product
Truett, Dale B.; Truett, Lila J.
2007-01-01
Authors of principles and price theory textbooks generally illustrate short-run production using a total product curve that displays first increasing and then diminishing marginal returns to employment of the variable input(s). Although it seems reasonable that a temporary range of increasing returns to variable inputs will likely occur as…
International Nuclear Information System (INIS)
Jones, R.M.; Miller, R.H.
1998-08-01
In order to reduce the dipole wake encountered by the first few bunches accelerated in a multi-bunch NLC scenario the DDS (damped detuned structure) was redesigned such that a much improved Gaussian fall-off occurs in the initial wake-function. From the 9 parameterized model of DDS1 the authors use a mapping function to allow DDS 3 and 4 to be modeled and hence avoid additional and prohibitively time consuming MAFIA runs. The equivalent circuit parameters and geometrical parameters are treated as functions of the synchronous frequency and are readily mapped onto the new synchronous frequencies. The new geometrical parameters form a family where each is associated with the iris diameter
Total scattering of disordered crystalline functional materials
International Nuclear Information System (INIS)
Shamoto, Shin-Ichi; Kodama, Katsuaki; Iikubo, Satoshi; Taguchi, Tomitsugu
2009-01-01
There are disorders in some modern functional materials. As an example, the crystalline phase of an optical recording material has low thermal conductivity but high electrical conductivity, simultaneously. This contradiction is a challenge to material scientists in designing good functional materials, which should have at least two types of crystallographic sites. One site limits thermal conductivity while the other site carries electrons or holes with high mobility. This problem exists with not only optical recording materials but also thermoelectric materials. The periodic boundary condition gets lost in the disordered parts. This therefore, makes atomic pair distribution function (PDF) analysis with a wide range of real space suitable for investigating the form and size of crystalline parts as well as disordered parts in the material. Pulsed neutron powder diffraction is one of the best tools for use in this new type of emerging research, together with synchrotron X-ray powder diffraction and electron diffraction.
Ventilated air cavities for the control of rising damp in historical buildings. Functional analysis
Directory of Open Access Journals (Sweden)
Mª T. Gil Muñoz
2018-01-01
Full Text Available This study analyzes the behavior of ventilated air cavities and their level of efficiency when used for the control of rising damp and the associated pathological damage in walls and foundations of historical buildings. The methodology is based on experiments on-site and monitoring. Knowledge of local climate conditions, the surroundings of the building, its construction features and the type of foundation constitute the preliminary conditions for the monitoring. In order to reach the goal we have measured several parameters according to a plan, developed graphical tools for the study, and prepared statistical data. The building of this system has not always been accompanied by a thorough assessment that would justify the intervention. The results show how this situation has affected the design strategies and sizing of the ventilated air cavities, limiting in many cases their efficiency.
Renal function after elective total hip replacement
DEFF Research Database (Denmark)
Perregaard, Helene; Damholt, Mette B; Solgaard, Søren
2016-01-01
Background and purpose - Acute kidney injury (AKI) is associated with increased short-term and long-term mortality in intensive care populations and in several surgical specialties, but there are very few data concerning orthopedic populations. We have studied the incidence of AKI and the prevale......Background and purpose - Acute kidney injury (AKI) is associated with increased short-term and long-term mortality in intensive care populations and in several surgical specialties, but there are very few data concerning orthopedic populations. We have studied the incidence of AKI...... and the prevalence of chronic kidney disease (CKD) in an elective population of orthopedic patients undergoing primary total hip replacement, hypothesizing that chronic kidney disease predisposes to AKI. Patients and methods - This was a single-center, population-based, retrospective, registry-based cohort study...... involving all primary elective total hip replacements performed from January 2003 through December 2012. Patient demographics and creatinine values were registered. We evaluated the presence of CKD and AKI according to the international guidelines for kidney disease (KDIGO Acute Kidney Injury Workgroup 2013...
International Nuclear Information System (INIS)
Ware, A.G.; Arendts, J.G.
1984-01-01
A program has been developed to assess the available piping damping data, to generate additional data and conduct seperate effects tests, and to establish a plan for reporting and storing future test results into a data bank. This effort is providing some of the basis for developing higher allowable damping values for piping seismic analyses, which will potentially permit removal of a considerable number of piping supports, particularly snubbers. This in turn will lead to more flexible piping systems which will be less susceptible to thermal cracking, will be easier to maintain and inspect, as well as less costly
International Nuclear Information System (INIS)
Panda, Satyajit; Ray, M C
2008-01-01
In this paper, a geometrically nonlinear dynamic analysis has been presented for functionally graded (FG) plates integrated with a patch of active constrained layer damping (ACLD) treatment and subjected to a temperature field. The constraining layer of the ACLD treatment is considered to be made of the piezoelectric fiber-reinforced composite (PFRC) material. The temperature field is assumed to be spatially uniform over the substrate plate surfaces and varied through the thickness of the host FG plates. The temperature-dependent material properties of the FG substrate plates are assumed to be graded in the thickness direction of the plates according to a power-law distribution while the Poisson's ratio is assumed to be a constant over the domain of the plate. The constrained viscoelastic layer of the ACLD treatment is modeled using the Golla–Hughes–McTavish (GHM) method. Based on the first-order shear deformation theory, a three-dimensional finite element model has been developed to model the open-loop and closed-loop nonlinear dynamics of the overall FG substrate plates under the thermal environment. The analysis suggests the potential use of the ACLD treatment with its constraining layer made of the PFRC material for active control of geometrically nonlinear vibrations of FG plates in the absence or the presence of the temperature gradient across the thickness of the plates. It is found that the ACLD treatment is more effective in controlling the geometrically nonlinear vibrations of FG plates than in controlling their linear vibrations. The analysis also reveals that the ACLD patch is more effective for controlling the nonlinear vibrations of FG plates when it is attached to the softest surface of the FG plates than when it is bonded to the stiffest surface of the plates. The effect of piezoelectric fiber orientation in the active constraining PFRC layer on the damping characteristics of the overall FG plates is also discussed
Panda, Satyajit; Ray, M. C.
2008-04-01
In this paper, a geometrically nonlinear dynamic analysis has been presented for functionally graded (FG) plates integrated with a patch of active constrained layer damping (ACLD) treatment and subjected to a temperature field. The constraining layer of the ACLD treatment is considered to be made of the piezoelectric fiber-reinforced composite (PFRC) material. The temperature field is assumed to be spatially uniform over the substrate plate surfaces and varied through the thickness of the host FG plates. The temperature-dependent material properties of the FG substrate plates are assumed to be graded in the thickness direction of the plates according to a power-law distribution while the Poisson's ratio is assumed to be a constant over the domain of the plate. The constrained viscoelastic layer of the ACLD treatment is modeled using the Golla-Hughes-McTavish (GHM) method. Based on the first-order shear deformation theory, a three-dimensional finite element model has been developed to model the open-loop and closed-loop nonlinear dynamics of the overall FG substrate plates under the thermal environment. The analysis suggests the potential use of the ACLD treatment with its constraining layer made of the PFRC material for active control of geometrically nonlinear vibrations of FG plates in the absence or the presence of the temperature gradient across the thickness of the plates. It is found that the ACLD treatment is more effective in controlling the geometrically nonlinear vibrations of FG plates than in controlling their linear vibrations. The analysis also reveals that the ACLD patch is more effective for controlling the nonlinear vibrations of FG plates when it is attached to the softest surface of the FG plates than when it is bonded to the stiffest surface of the plates. The effect of piezoelectric fiber orientation in the active constraining PFRC layer on the damping characteristics of the overall FG plates is also discussed.
Energy Technology Data Exchange (ETDEWEB)
Rudolph, E [Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (F.R. Germany)
1975-01-01
As a model for gravitational radiation damping of a planet the electromagnetic radiation damping of an extended charged body moving in an external gravitational field is calculated in harmonic coordinates using a weak field, slowing-motion approximation. Special attention is paid to the case where this gravitational field is a weak Schwarzschild field. Using Green's function methods for this purpose it is shown that in a slow-motion approximation there is a strange connection between the tail part and the sharp part: radiation reaction terms of the tail part can cancel corresponding terms of the sharp part. Due to this cancelling mechanism the lowest order electromagnetic radiation damping force in an external gravitational field in harmonic coordinates remains the flat space Abraham Lorentz force. It is demonstrated in this simplified model that a naive slow-motion approximation may easily lead to divergent higher order terms. It is shown that this difficulty does not arise up to the considered order.
Long-Range Corrected Hybrid Density Functionals with Damped Atom-Atom Dispersion Corrections
Energy Technology Data Exchange (ETDEWEB)
Chai, Jeng-Da; Head-Gordon, Martin
2008-06-14
We report re-optimization of a recently proposed long-range corrected (LC) hybrid density functionals [J.-D. Chai and M. Head-Gordon, J. Chem. Phys. 128, 084106 (2008)] to include empirical atom-atom dispersion corrections. The resulting functional, {omega}B97X-D yields satisfactory accuracy for thermochemistry, kinetics, and non-covalent interactions. Tests show that for non-covalent systems, {omega}B97X-D shows slight improvement over other empirical dispersion-corrected density functionals, while for covalent systems and kinetics, it performs noticeably better. Relative to our previous functionals, such as {omega}B97X, the new functional is significantly superior for non-bonded interactions, and very similar in performance for bonded interactions.
Open Maximal Mucosa-Sparing Functional Total Laryngectomy
Directory of Open Access Journals (Sweden)
Pavel Dulguerov
2017-10-01
Full Text Available BackgroundTotal laryngectomy after (chemoradiotherapy is associated with a high incidence of fistula and therefore flaps are advocated. The description of a transoral robotic total laryngectomy prompted us to develop similar minimally invasive open approaches for functional total laryngectomy.MethodsA retrospective study of consecutive unselected patients with a dysfunctional larynx after (chemoradiation that underwent open maximal mucosal-sparing functional total laryngectomy (MMSTL between 2014 and 2016 is presented. The surgical technique is described, and the complications and functional outcome are reviewed.ResultsThe cohorts included 10 patients who underwent open MMSTL. No pedicled flap was used. Only one postoperative fistula was noted (10%. All patients resumed oral diet and experienced a functional tracheo-esophageal voice.ConclusionMMSTL could be used to perform functional total laryngectomy without a robot and with minimal incidence of complications.
International Nuclear Information System (INIS)
Drouin, M.
2009-11-01
This research thesis proposes a new formulation of the relativistic implicit direct method, based on the weak formulation of the wave equation which is solved by means of a Newton algorithm. The first part of this thesis deals with the properties of the explicit particle-in-cell (PIC) methods: properties and limitations of an explicit PIC code, linear analysis of a numerical plasma, numerical heating phenomenon, interest of a higher order interpolation function, and presentation of two applications in high density relativistic laser-plasma interaction. The second and main part of this report deals with adapting the direct implicit method to laser-plasma interaction: presentation of the state of the art, formulating of the direct implicit method, resolution of the wave equation. The third part concerns various numerical and physical validations of the ELIXIRS code: case of laser wave propagation in vacuum, demonstration of the adjustable damping which is a characteristic of the proposed algorithm, influence of space-time discretization on energy conservation, expansion of a thermal plasma in vacuum, two cases of plasma-beam unsteadiness in relativistic regime, and then a case of the overcritical laser-plasma interaction
a locally adapted functional outcome measurement score for total
African Journals Online (AJOL)
Results and success of total hip arthroplasty are often measured using a functional outcome scoring system. Most current scores were developed in Europe and. North America (1-3). During the evaluation of a Total. Hip Replacement (THR) project in Ouagadougou,. Burkina Faso (4) it was felt that these scores were not.
KLE Translog production function and total factor productivity
Czech Academy of Sciences Publication Activity Database
Klacek, J.; Vošvrda, Miloslav; Schlosser, Š.
2007-01-01
Roč. 87, č. 4 (2007), s. 261-274 ISSN 0322-788X Institutional research plan: CEZ:AV0Z10750506 Keywords : total factor productivity * translog production function * aggregate production function * least squares method * ridge regression Subject RIV: AH - Economics
Jowett, John M; Zimmermann, Frank; Owen, H
2001-01-01
The Compact Linear Colider (CLIC) is designed to operate at 3 TeV centre-of-mass energy with a total luminosity of 10^35 cm^-2 s^-1. The overall system design leads to extremely demanding requirements on the bunch trains injected into the main libac at frequency of 100 Hz. In particular, the emittances of the intense bunches have to be about an order of magnitude smaller than presently achieved. We describe our approach to finding a damping ring design capable of meeting these requirements. Besides lattice design, emittance and damping rate considerations, a number of scattering and instability effects have to be incorporated into the optimisation of parameters. Among these, intra-bem scattering and the electron cloud effect are two of the most significant.
Mouhot, Clément
2011-09-01
Going beyond the linearized study has been a longstanding problem in the theory of Landau damping. In this paper we establish exponential Landau damping in analytic regularity. The damping phenomenon is reinterpreted in terms of transfer of regularity between kinetic and spatial variables, rather than exchanges of energy; phase mixing is the driving mechanism. The analysis involves new families of analytic norms, measuring regularity by comparison with solutions of the free transport equation; new functional inequalities; a control of non-linear echoes; sharp "deflection" estimates; and a Newton approximation scheme. Our results hold for any potential no more singular than Coulomb or Newton interaction; the limit cases are included with specific technical effort. As a side result, the stability of homogeneous equilibria of the non-linear Vlasov equation is established under sharp assumptions. We point out the strong analogy with the KAM theory, and discuss physical implications. Finally, we extend these results to some Gevrey (non-analytic) distribution functions. © 2011 Institut Mittag-Leffler.
The Duffing oscillator with damping
DEFF Research Database (Denmark)
Johannessen, Kim
2015-01-01
An analytical solution to the differential equation describing the Duffing oscillator with damping is presented. The damping term of the differential equation and the initial conditions satisfy an algebraic equation, and thus the solution is specific for this type of damping. The nonlinear term...... of the differential equation is allowed to be considerable compared to the linear term. The solution is expressed in terms of the Jacobi elliptic functions by including a parameter-dependent elliptic modulus. The analytical solution is compared to the numerical solution, and the agreement is found to be very good....... It is established that the period of oscillation is shorter compared to that of a linearized model but increasing with time and asymptotically approaching the period of oscillation of the linear damped model. An explicit expression for the period of oscillation has been derived, and it is found to be very accurate....
The γ total cross section and the photon structure functions
International Nuclear Information System (INIS)
Alexander, G.
1986-01-01
A review on the current experimental status of the photon-photon total hadronic cross section as a function of energy and Q 2 is given in addition to the results obtained for the leptonic and hadronic photon structure functions. The results are discussed in terms of the point-like part of the photon and non-perturbative VDM part. It is shown that the cross section at Q 2 = 0 is well described by VDM derived models
Damped nonlinear Schrodinger equation
International Nuclear Information System (INIS)
Nicholson, D.R.; Goldman, M.V.
1976-01-01
High frequency electrostatic plasma oscillations described by the nonlinear Schrodinger equation in the presence of damping, collisional or Landau, are considered. At early times, Landau damping of an initial soliton profile results in a broader, but smaller amplitude soliton, while collisional damping reduces the soliton size everywhere; soliton speeds at early times are unchanged by either kind of damping. For collisional damping, soliton speeds are unchanged for all time
Functional assessment of patients after total knee replacement
Directory of Open Access Journals (Sweden)
Matla Joanna
2017-06-01
Full Text Available Introduction: In the society of the 21st century, osteoarthritis is considered one of the primary causes of the occurrence of pain and disability. Arthroplasty is the treatment of choice for advanced degenerative changes. The aim of the study was to carry out a functional assessment of patients at early stages of rehabilitation after total knee replacement.
Communication, functional disorders and lifestyle changes after total laryngectomy
Ackerstaff, A. H.; Hilgers, F. J.; Aaronson, N. K.; Balm, A. J.
1994-01-01
Functional changes after total laryngectomy, including voice quality, hyposmia and dysgeusia, nasal discharge, swallowing and smoking habits were studied by means of a structured interview with 63 laryngectomized patients. Eighty per cent of the patients reported that they were satisfied with the
Tambasco, Claudia; Barranco Garcia, Javier; Boccardi, Andrea; Buffat, Xavier; Bruce, Roderik; Gasior, Marek; Hostettler, Michi; Lefevre, Thibaut; Louro Alves, Diogo Miguel; Metral, Elias; Persson, Tobias Hakan Bjorn; Pieloni, Tatiana; Pojer, Mirko; Salvachua Ferrando, Belen Maria; Solfaroli Camillocci, Matteo; CERN. Geneva. ATS Department
2018-01-01
Beam Transfer Function (BTF) measurements are direct measurement of the stability diagrams that deﬁne the stability threshold of coherent beam instabilities driven by the impedance. At the LHC, some coherent instabilities at ﬂat top energy are still not fully understood and the BTF measurements provide a method to experimentally probe the Landau damping of the proton beams. The BTF response is sensitive to the particle distribution changes and contain information about the transverse tune spread in the beams. The BTF system has been installed in the LHC in the 2015 in order to investigate the Landau damping at different stages of the operational cycle, machine conﬁgurations (different octupole currents, crossing angles, tunes etc...) and in presence of beam-beam excited resonances that may provoke diffusion mechanisms with a consequence change of Landau damping. Past MDs showed some difﬁculties for the reconstruction of the stability diagram from BTF measurements and several improvements on the BTF sy...
Renal Function Recovery with Total Artificial Heart Support.
Quader, Mohammed A; Goodreau, Adam M; Shah, Keyur B; Katlaps, Gundars; Cooke, Richard; Smallfield, Melissa C; Tchoukina, Inna F; Wolfe, Luke G; Kasirajan, Vigneshwar
2016-01-01
Heart failure patients requiring total artificial heart (TAH) support often have concomitant renal insufficiency (RI). We sought to quantify renal function recovery in patients supported with TAH at our institution. Renal function data at 30, 90, and 180 days after TAH implantation were analyzed for patients with RI, defined as hemodialysis supported or an estimated glomerular filtration rate (eGFR) less than 60 ml/min/1.73 m. Between January 2008 and December 2013, 20 of the 46 (43.5%) TAH recipients (age 51 ± 9 years, 85% men) had RI, mean preoperative eGFR of 48 ± 7 ml/min/1.73 m. Renal function recovery was noted at each follow-up interval: increment in eGFR (ml/min/1.73 m) at 30, 90, and 180 days was 21 ± 35 (p = 0.1), 16.5 ± 18 (p = 0.05), and 10 ± 9 (p = 0.1), respectively. Six patients (30%) required preoperative dialysis. Of these, four recovered renal function, one remained on dialysis, and one died. Six patients (30%) required new-onset dialysis. Of these, three recovered renal function and three died. Overall, 75% (15 of 20) of patients' renal function improved with TAH support. Total artificial heart support improved renal function in 75% of patients with pre-existing significant RI, including those who required preoperative dialysis.
On Collisionless Damping of Ion Acoustic Waves
DEFF Research Database (Denmark)
Jensen, Vagn Orla; Petersen, P.I.
1973-01-01
Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero.......Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero....
Total Correlation Function Integrals and Isothermal Compressibilities from Molecular Simulations
DEFF Research Database (Denmark)
Wedberg, Rasmus; Peters, Günther H.j.; Abildskov, Jens
2008-01-01
Generation of thermodynamic data, here compressed liquid density and isothermal compressibility data, using molecular dynamics simulations is investigated. Five normal alkane systems are simulated at three different state points. We compare two main approaches to isothermal compressibilities: (1...... in approximately the same amount of time. This suggests that computation of total correlation function integrals is a route to isothermal compressibility, as accurate and fast as well-established benchmark techniques. A crucial step is the integration of the radial distribution function. To obtain sensible results...
Damping rates of the SRRC storage ring
International Nuclear Information System (INIS)
Hsu, K.T.; Kuo, C.C.; Lau, W.K.; Weng, W.T.
1995-01-01
The SRRC storage ring is a low emittance synchrotron radiation machine with nominal operation energy 1.3 GeV. The design damping time due to synchrotron radiation is 10.7, 14.4, 8.7 ms for the horizontal, vertical and longitudinal plane, respectively. The authors measured the real machine damping time as a function of bunch current, chromaticity, etc. To damp the transverse beam instability, especially in the vertical plane, they need to increase chromaticity to large positive value. The damping rates are much larger than the design values. Landau damping contribution in the longitudinal plane is quite large, especially in the multibunch mode. The estimated synchrotron tune spread from the Landau damping is in agreement with the measured coherent longitudinal coupled bunch oscillation amplitude
Directory of Open Access Journals (Sweden)
S. Zhu
1998-01-01
Full Text Available Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficients, some of which cannot be measured indirectly.
Power oscillation damping controller
DEFF Research Database (Denmark)
2012-01-01
A power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control...
Exponential decay for solutions to semilinear damped wave equation
Gerbi, Sté phane; Said-Houari, Belkacem
2011-01-01
This paper is concerned with decay estimate of solutions to the semilinear wave equation with strong damping in a bounded domain. Intro- ducing an appropriate Lyapunov function, we prove that when the damping is linear, we can find initial data
Overview on methods for formulating explicit damping matrices for non-classically damped structures
International Nuclear Information System (INIS)
Xu, J.
1998-04-01
In computing the dynamic response of a connected system with multiple components having dissimilar damping characteristics, which is often referred to as nonclassically damped system such as nuclear power plant piping systems supported by stiff structures, one needs to define the system-level damping based upon the damping information of components. This is frequently done in practice using approximate methods expressed as composite modal damping with weighting functions. However, when the difference in damping among components is substantial, the composite modal damping may become inappropriate in the characterization of the damping behavior of such systems. In recent years, several new methods have emerged with the expectation that they could produce more exact system-level damping for a group of nonclassically damped structures which are comprised of components that possess classical modal damping. In this paper, an overview is presented to examine these methods in the light of their theoretical basis, the technical merits, and practical applications. To this end, a synthesis method is described, which was shown to reduce to the other methods in the literature
Rotational damping motion in nuclei
International Nuclear Information System (INIS)
Egido, J.L.; Faessler, A.
1991-01-01
The recently proposed model to explain the mechanism of the rotational motion damping in nuclei is exactly solved. When compared with the earlier approximative solution, we find significative differences in the low excitation energy limit (i.e. Γ μ 0 ). For the strength functions we find distributions going from the Wigner semicircle through gaussians to Breit-Wigner shapes. (orig.)
The damped wave equation with unbounded damping
Czech Academy of Sciences Publication Activity Database
Freitas, P.; Siegl, Petr; Tretter, C.
2018-01-01
Roč. 264, č. 12 (2018), s. 7023-7054 ISSN 0022-0396 Institutional support: RVO:61389005 Keywords : damped wave equation * unbounded damping * essential spectrum * quadratic operator funciton with unbounded coefficients * Schrodinger operators with complex potentials Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 1.988, year: 2016
Total Variation Regularization for Functions with Values in a Manifold
Lellmann, Jan; Strekalovskiy, Evgeny; Koetter, Sabrina; Cremers, Daniel
2013-01-01
While total variation is among the most popular regularizers for variational problems, its extension to functions with values in a manifold is an open problem. In this paper, we propose the first algorithm to solve such problems which applies to arbitrary Riemannian manifolds. The key idea is to reformulate the variational problem as a multilabel optimization problem with an infinite number of labels. This leads to a hard optimization problem which can be approximately solved using convex relaxation techniques. The framework can be easily adapted to different manifolds including spheres and three-dimensional rotations, and allows to obtain accurate solutions even with a relatively coarse discretization. With numerous examples we demonstrate that the proposed framework can be applied to variational models that incorporate chromaticity values, normal fields, or camera trajectories. © 2013 IEEE.
Total Variation Regularization for Functions with Values in a Manifold
Lellmann, Jan
2013-12-01
While total variation is among the most popular regularizers for variational problems, its extension to functions with values in a manifold is an open problem. In this paper, we propose the first algorithm to solve such problems which applies to arbitrary Riemannian manifolds. The key idea is to reformulate the variational problem as a multilabel optimization problem with an infinite number of labels. This leads to a hard optimization problem which can be approximately solved using convex relaxation techniques. The framework can be easily adapted to different manifolds including spheres and three-dimensional rotations, and allows to obtain accurate solutions even with a relatively coarse discretization. With numerous examples we demonstrate that the proposed framework can be applied to variational models that incorporate chromaticity values, normal fields, or camera trajectories. © 2013 IEEE.
Cardiopulmonary function and oxygen delivery during total liquid ventilation.
Tsagogiorgas, Charalambos; Alb, Markus; Herrmann, Peter; Quintel, Michael; Meinhardt, Juergen P
2011-10-01
Total liquid ventilation (TLV) with perfluorocarbons has shown to improve cardiopulmonary function in the injured and immature lung; however there remains controversy over the normal lung. Hemodynamic effects of TLV in the normal lung currently remain undetermined. This study compared changes in cardiopulmonary and circulatory function caused by either liquid or gas tidal volume ventilation. In a prospective, controlled study, 12 non-injured anesthetized, adult New Zealand rabbits were primarily conventionally gas-ventilated (CGV). After instrumentation for continuous recording of arterial (AP), central venous (CVP), left artrial (LAP), pulmonary arterial pressures (PAP), and cardiac output (CO) animals were randomized into (1) CGV group and (2) TLV group. In the TLV group partial liquid ventilation was initiated with instillation of perfluoroctylbromide (12 ml/kg). After 15 min, TLV was established for 3 hr applying a volume-controlled, pressure-limited, time-cycled ventilation mode using a double-piston configured TLV. Controls (CGV) remained gas-ventilated throughout the experiment. During TLV, heart rate, CO, PAP, MAP, CVP, and LAP as well as derived hemodynamic variables, arterial and mixed venous blood gases, oxygen delivery, PVR, and SVR did not differ significantly compared to CGV. Liquid tidal volumes suitable for long-term TLV in non-injured rabbits do not significantly impair CO, blood pressure, and oxygen dynamics when compared to CGV. Copyright © 2011 Wiley-Liss, Inc.
Labonnote, Nathalie
2012-01-01
Key point to development of environmentally friendly timber structures, appropriate to urban ways of living, is the development of high-rise timber buildings. Comfort properties are nowadays one of the main limitations to tall timber buildings, and an enhanced knowledge on damping phenomena is therefore required, as well as improved prediction models for damping. The aim of this work has consequently been to estimate various damping quantities in timber structures. In particular, models h...
Decoherence and Landau-Damping
Energy Technology Data Exchange (ETDEWEB)
Ng, K.Y.; /Fermilab
2005-12-01
The terminologies, decoherence and Landau damping, are often used concerning the damping of a collective instability. This article revisits the difference and relation between decoherence and Landau damping. A model is given to demonstrate how Landau damping affects the rate of damping coming from decoherence.
Pápai, Ferenc; Szűcs, István
2015-01-01
The singular value decomposition of the measured frequency response function matrix, as a very effective tool of experimental modal analysis is used over the last twenty-five years. The complex mode indication function has become a common numerical tool in processing experimental data. There are many references on the development of complex mode indication function including the enhanced mode indication function and its use together with the enhanced frequency response function to form spatia...
Pápai, Ferenc; Szűcs, István
2015-01-01
The singular value decomposition of the measured frequency response function matrix, as a very effective tool of experimental modal analysis is used over the last twenty-five years. The complex mode indication function has become a common numerical tool in processing experimental data. There are many references on the development of complex mode indication function including the enhanced mode indication function and its use together with the enhanced frequency response function to form spatia...
Energy Technology Data Exchange (ETDEWEB)
Lee, Kanghee; Kang, Heungseok; Oh, Dongseok; Yoon, Kyungho; Kim, Hyungkyu; Kim, Jaeyong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2013-10-15
This paper summary the fuel assembly damping data in air/in still water/under flow, released from foreign fuel vendors, compared our data with the published data. Some technical issues in fuel assembly damping measurement testing are also briefly discussed. Understanding of each fuel assembly damping mechanisms according to the surrounding medium and flow velocity can support the fuel design improvement in fuel assembly dynamics and structural integrity aspect. Because the upgraded requirements of the newly-developed advanced reactor system will demands to minimize fuel design margin in integrity evaluation, reduction in conservatism of fuel assembly damping can contribute to alleviate the fuel design margin for sure. Damping is an energy dissipation mechanism in a vibrating mechanical structure and prevents a resonant structure from having infinite vibration amplitudes. The sources of fuel assembly damping are various from support friction to flow contribution, and it can be increased by the viscosity or drag of surrounding fluid medium or the average velocity of water flowing. Fuel licensing requires fuel design evaluation in transient or accidental condition. Dynamic response analysis of fuel assembly is to show fuel integrity and requires information on assembly-wise damping in dry condition and under wet or water flowing condition. However, damping measurement test for the full-scale fuel assembly prototype is not easy to carry out because of the scale (fuel prototype, test facility), unsteadiness of test data (scattering, random sampling and processing), instrumentation under water flowing (water-proof response measurement), and noise. LWR fuel technology division in KAERI is preparing the infra structure for damping measurement test of full-scale fuel assembly, to support fuel industries and related research activities. Here is a preliminary summary of fuel assembly damping, published in the literature. Some technical issues in fuel assembly damping
Mandzuk, Lynda L; McMillan, Diana E; Bohm, Eric R
2015-05-01
Primary total hip and primary total knee surgeries are commonly performed to improve patients' quality of life and functional status. This longitudinal retrospective study (N = 851) examined self-reported quality of life and functional status over the preoperative and postoperative periods: 12 months prior to surgery, one month prior to surgery and 12 months following surgery. A linear mixed effects model was used to analyze the changes in quality of life and functional status over the sampling period. Patients in the convenience sample reported improvements in quality of life and functional status utilizing the SF-12 and Oxford Hip and Oxford Knee, although differences were noted by procedure and gender. Total hip patients tended to demonstrate greater improvement than total knee patients and males reported higher levels of physical and mental quality of life as well as functional status when compared to females. Of particular note was that mental health scores were consistently lower in both total hip and total knee replacement patients across the perioperative period and up to one year postoperative. This study identifies an opportunity for health care providers to proactively address the mental health of total hip and total knee replacement patients throughout their joint replacement trajectory. Copyright © 2014 Elsevier Ltd. All rights reserved.
Multiparticle phenomena and Landau damping
International Nuclear Information System (INIS)
Talman, R.
1987-01-01
The purpose of this paper is to survey various methods of studying multiparticle phenomena in accelerators. Both experimental and theoretical methods are described. An effort has been made to emphasize the intuitive and qualitative aspects rather than the detailed mathematics. Some of the terms or concepts to be explained are coherent and incoherent tunes, normal modes, Landau damping, beam-transfer functions, and feedback. These are all of daily importance in the interpretation of colliding-beam observations and the control of performance
Tuned mass absorbers on damped structures under random load
DEFF Research Database (Denmark)
Krenk, Steen; Høgsberg, Jan Becker
2008-01-01
the mass ratio alone, and the damping can be determined subsequently. Only approximate results are available for the influence of damping in the original structure, typically in the form of series expansions. In the present paper it is demonstrated that for typical mass ratios in the order of a few percent......A substantial literature exists on the optimal choice of parameters of a tuned mass absorber on a structure excited by a force or by ground acceleration with random characteristics in the form of white noise. In the absence of structural damping the optimal frequency tuning is determined from...... for the response variance of a structure with initial damping in terms of the mass ratio and both damping ratios. Within this format the optimal tuning of the absorber turns out to be independent of the structural damping, and a simple explicit expression is obtained for the equivalent total damping....
HIGH ECCENTRICITY EOQ TOTAL COST FUNCTION YIELDS JIT RESULTs
Directory of Open Access Journals (Sweden)
Willian Roach
2010-06-01
Full Text Available No estoque de bens perecíveis, o custo de armazenamento H é muito maior do que o previsto na fórmula clássica do lote econômico do pedido (EOQ. Para bens perecíveis, a função custo total no EOQ é um pico e não uma reta horizontal. Esta forma pontiaguda leva o modelo EOQ a produzir entregas just in time (JIT - resultados semelhantes. O efeito pontiagudo (excentricidade da curva de custo total do lote econômico EOQ depende apenas do custo de armazenamento (H e não da demanda anual (D ou do custo do pedido (S. D e S determinam o nível (altura da curva de custo total do estoque (TC, mas não a forma.
International Nuclear Information System (INIS)
Jones, R.M.; Miller, R.H.; Kroll, N.M.
1997-05-01
Transverse wake functions so far reported for the SLAC DDS have been limited to those caused by uniform offset of the drive beam in a straight perfectly aligned structure. The complete description of the betatron oscillations of wake coupled bunches requires an array of wake functions, referred to as moments. Modifications of these arrays induced by structure misalignments are also of interest. In this paper we express the array elements in terms of a spectral function array. Examples are given based upon DDS1
Isar, Aurelian
1995-01-01
The harmonic oscillator with dissipation is studied within the framework of the Lindblad theory for open quantum systems. By using the Wang-Uhlenbeck method, the Fokker-Planck equation, obtained from the master equation for the density operator, is solved for the Wigner distribution function, subject to either the Gaussian type or the delta-function type of initial conditions. The obtained Wigner functions are two-dimensional Gaussians with different widths. Then a closed expression for the density operator is extracted. The entropy of the system is subsequently calculated and its temporal behavior shows that this quantity relaxes to its equilibrium value.
A locally adapted functional outcome measurement score for total ...
African Journals Online (AJOL)
... in Europe or North America and seem not optimally suited for a general West ... We introduce a cross-cultural adaptation of the Lequesne index as a new score. ... Keywords: THR, Hip, Africa, Functional score, Hip replacement, Arthroscopy ...
DAMPs, ageing, and cancer: The 'DAMP Hypothesis'.
Huang, Jin; Xie, Yangchun; Sun, Xiaofang; Zeh, Herbert J; Kang, Rui; Lotze, Michael T; Tang, Daolin
2015-11-01
Ageing is a complex and multifactorial process characterized by the accumulation of many forms of damage at the molecular, cellular, and tissue level with advancing age. Ageing increases the risk of the onset of chronic inflammation-associated diseases such as cancer, diabetes, stroke, and neurodegenerative disease. In particular, ageing and cancer share some common origins and hallmarks such as genomic instability, epigenetic alteration, aberrant telomeres, inflammation and immune injury, reprogrammed metabolism, and degradation system impairment (including within the ubiquitin-proteasome system and the autophagic machinery). Recent advances indicate that damage-associated molecular pattern molecules (DAMPs) such as high mobility group box 1, histones, S100, and heat shock proteins play location-dependent roles inside and outside the cell. These provide interaction platforms at molecular levels linked to common hallmarks of ageing and cancer. They can act as inducers, sensors, and mediators of stress through individual plasma membrane receptors, intracellular recognition receptors (e.g., advanced glycosylation end product-specific receptors, AIM2-like receptors, RIG-I-like receptors, and NOD1-like receptors, and toll-like receptors), or following endocytic uptake. Thus, the DAMP Hypothesis is novel and complements other theories that explain the features of ageing. DAMPs represent ideal biomarkers of ageing and provide an attractive target for interventions in ageing and age-associated diseases. Copyright © 2014 Elsevier B.V. All rights reserved.
Lázaro, Mario
2018-01-01
In this paper, nonviscous, nonproportional, vibrating structures are considered. Nonviscously damped systems are characterized by dissipative mechanisms which depend on the history of the response velocities via hereditary kernel functions. Solutions of the free motion equation lead to a nonlinear eigenvalue problem involving mass, stiffness and damping matrices. Viscoelasticity leads to a frequency dependence of this latter. In this work, a novel closed-form expression to estimate complex eigenvalues is derived. The key point is to consider the damping model as perturbed by a continuous fictitious parameter. Assuming then the eigensolutions as function of this parameter, the computation of the eigenvalues sensitivity leads to an ordinary differential equation, from whose solution arises the proposed analytical formula. The resulting expression explicitly depends on the viscoelasticity (frequency derivatives of the damping function), the nonproportionality (influence of the modal damping matrix off-diagonal terms). Eigenvectors are obtained using existing methods requiring only the corresponding eigenvalue. The method is validated using a numerical example which compares proposed with exact ones and with those determined from the linear first order approximation in terms of the damping matrix. Frequency response functions are also plotted showing that the proposed approach is valid even for moderately or highly damped systems.
Extended Rayleigh Damping Model
Directory of Open Access Journals (Sweden)
Naohiro Nakamura
2016-07-01
Full Text Available In dynamic analysis, frequency domain analysis can be used if the entire structure is linear. However, time history analysis is generally used if nonlinear elements are present. Rayleigh damping has been widely used in time history response analysis. Many articles have reported the problems associated with this damping and suggested remedies. A basic problem is that the frequency area across which the damping ratio is almost constant is too narrow. If the area could be expanded while incurring only a small increase in computational cost, this would provide an appropriate remedy for this problem. In this study, a novel damping model capable of expanding the constant frequency area by more than five times was proposed based on the study of a causal damping model. This model was constructed by adding two terms to the Rayleigh damping model and can be applied to the linear elements in the time history analysis of a nonlinear structure. The accuracy and efficiency of the model were confirmed using example analyses.
The DAMPE silicon tungsten tracker
Gallo, Valentina; Asfandiyarov, R; Azzarello, P; Bernardini, P; Bertucci, B; Bolognini, A; Cadoux, F; Caprai, M; Domenjoz, M; Dong, Y; Duranti, M; Fan, R; Franco, M; Fusco, P; Gargano, F; Gong, K; Guo, D; Husi, C; Ionica, M; Lacalamita, N; Loparco, F; Marsella, G; Mazziotta, M N; Mongelli, M; Nardinocchi, A; Nicola, L; Pelleriti, G; Peng, W; Pohl, M; Postolache, V; Qiao, R; Surdo, A; Tykhonov, A; Vitillo, S; Wang, H; Weber, M; Wu, D; Wu, X; Zhang, F; De Mitri, I; La Marra, D
2017-01-01
The DArk Matter Particle Explorer (DAMPE) satellite has been successfully launched on the 17th December 2015. It is a powerful space detector designed for the identification of possible Dark Matter signatures thanks to its capability to detect electrons and photons with an unprecedented energy resolution in an energy range going from few GeV up to 10 TeV. Moreover, the DAMPE satellite will contribute to a better understanding of the propagation mechanisms of high energy cosmic rays measuring the nuclei flux up to 100 TeV. DAMPE is composed of four sub-detectors: a plastic strip scintillator, a silicon-tungsten tracker-converter (STK), a BGO imaging calorimeter and a neutron detector. The STK is made of twelve layers of single-sided AC-coupled silicon micro-strip detectors for a total silicon area of about 7 $m^2$ . To promote the conversion of incident photons into electron-positron pairs, tungsten foils are inserted into the supporting structure. In this document, a detailed description of the STK constructi...
Simplified Model of Nonlinear Landau Damping
International Nuclear Information System (INIS)
Yampolsky, N.A.; Fisch, N.J.
2009-01-01
The nonlinear interaction of a plasma wave with resonant electrons results in a plateau in the electron distribution function close to the phase velocity of the plasma wave. As a result, Landau damping of the plasma wave vanishes and the resonant frequency of the plasma wave downshifts. However, this simple picture is invalid when the external driving force changes the plasma wave fast enough so that the plateau cannot be fully developed. A new model to describe amplification of the plasma wave including the saturation of Landau damping and the nonlinear frequency shift is proposed. The proposed model takes into account the change of the plasma wave amplitude and describes saturation of the Landau damping rate in terms of a single fluid equation, which simplifies the description of the inherently kinetic nature of Landau damping. A proposed fluid model, incorporating these simplifications, is verified numerically using a kinetic Vlasov code.
Foundations of Total Functional Data-Flow Programming
Directory of Open Access Journals (Sweden)
Baltasar Trancón y Widemann
2014-06-01
Full Text Available The field of declarative stream programming (discrete time, clocked synchronous, modular, data-centric is divided between the data-flow graph paradigm favored by domain experts, and the functional reactive paradigm favored by academics. In this paper, we describe the foundations of a framework for unifying functional and data-flow styles that differs from FRP proper in significant ways: It is based on set theory to match the expectations of domain experts, and the two paradigms are reduced symmetrically to a low-level middle ground, with strongly compositional semantics. The design of the framework is derived from mathematical first principles, in particular coalgebraic coinduction and a standard relational model of stateful computation. The abstract syntax and semantics introduced here constitute the full core of a novel stream programming language.
International Nuclear Information System (INIS)
Phuoc, Le Minh; Lee, Suk Han; Kim, Hun Mo; Martinet, Philippe
2008-01-01
Robot inverse kinematics based on Jacobian inversion encounters critical issues of kinematic singularities. In this paper, several techniques based on damped least squares are proposed to lead robot pass through kinematic singularities without excessive joint velocities. Unlike other work in which the same damping factor is used for all singular vectors, this paper proposes a different damping coefficient for each singular vector based on corresponding singular value of the Jacobian. Moreover, a continuous distribution of damping factor following Gaussian function guarantees the continuous in joint velocities. A genetic algorithm is utilized to search for the best maximum damping factor and singular region, which used to require ad hoc searching in other works. As a result, end effector tracking error, which is inherited from damped least squares by introducing damping factors, is minimized. The effectiveness of our approach is compared with other methods in both non-redundant robot and redundant robot
Energy Technology Data Exchange (ETDEWEB)
Phuoc, Le Minh; Lee, Suk Han; Kim, Hun Mo [Sungkyunkwan University, Suwon (Korea, Republic of); Martinet, Philippe [Blaise Pascal University, Clermont-Ferrand Cedex (France)
2008-07-15
Robot inverse kinematics based on Jacobian inversion encounters critical issues of kinematic singularities. In this paper, several techniques based on damped least squares are proposed to lead robot pass through kinematic singularities without excessive joint velocities. Unlike other work in which the same damping factor is used for all singular vectors, this paper proposes a different damping coefficient for each singular vector based on corresponding singular value of the Jacobian. Moreover, a continuous distribution of damping factor following Gaussian function guarantees the continuous in joint velocities. A genetic algorithm is utilized to search for the best maximum damping factor and singular region, which used to require ad hoc searching in other works. As a result, end effector tracking error, which is inherited from damped least squares by introducing damping factors, is minimized. The effectiveness of our approach is compared with other methods in both non-redundant robot and redundant robot
International Nuclear Information System (INIS)
Thielen, M; Schmitt, C N Z; Eckert, S; Speck, T; Seidel, R
2013-01-01
The mechanical properties of artificial foams are mainly determined by the choice of bulk materials and relative density. In natural foams, in contrast, variation to optimize properties is achieved by structural optimization rather than by conscious substitution of bulk materials. Pomelos (Citrus maxima) have a thick foam-like peel which is capable of dissipating considerable amounts of kinetic energy and thus this fruit represents an ideal role model for the development of biomimetic impact damping structures. This paper focuses on the analysis of the biomechanics of the pomelo peel and on its structure–function relationship. It deals with the determination of the onset strain of densification of this foam-like tissue and on how this property is influenced by the arrangement of vascular bundles. It was found here that the vascular bundles branch in a very regular manner—every 16.5% of the radial peel thickness—and that the surrounding peel tissue (pericarp) attains its exceptional thickness mainly by the expansion of existing interconnected cells causing an increasing volume of the intercellular space, rather than by cell division. These findings lead to the discussion of the pomelo peel as an inspiration for fibre-reinforced cast metallic foams with the capacity for excellent energy dissipation. (paper)
The calculated longitudinal impedance of the SLC [Stanford Linear Collider] damping rings
International Nuclear Information System (INIS)
Bane, K.L.F.
1988-05-01
A high level of current dependent bunch lengthening has been observed in the north damping ring of the Stanford Linear Collider (SLC), indicating that the ring's impedance is very inductive. This level of bunch lengthening will limit the performance of the SLC. In order to study the problem of bunch lengthening in the damping ring and the possibility of reducing their inductance we compute, in this report, the longitudinal impedance of the damping ring vacuum chamber. More specifically we find the response function of the ring to a short gaussian bunch. This function will later be used as a driving term in the longitudinal equation of motion. We also identify the important inductive elements of the vacuum chamber and estimate their contribution to the total ring inductance. This information will be useful in assessing the effect of vacuum chamber modifications. 7 refs. , 8 figs., 1 tab
Confirmation of soil radiation damping from test versus analysis
International Nuclear Information System (INIS)
Eidinger, J.M.; Mukhim, G.S.; Desmond, T.P.
1987-01-01
The work was performed to demonstrate that soil-structure interaction effects for nuclear plant structures can be accurately (and conservatively) predicted using the finite element or soil spring methods of soil-structure interaction analysis. Further, the work was done to investigate the relative importance of soil radiation versus soil material damping in the total soil damping analytical treatment. The analytical work was benchmarked with forced vibration tests of a concrete circular slab resting on the soil surface. The applied loading was in the form of a suddenly applied pulse load, or snapback. The measured responses of the slap represent the free vibration of the slab after the pulse load has been applied. This simplifies the interpretation of soil damping, by the use of the logarithmic decay formulation. To make comparisons with the test results, the damping data calculated from the analytical models is also based on the logarithmic decay formulation. An attempt is made to differentiate the observed damped behavior of the concrete slab as being caused by soil radiation versus soil material damping. It is concluded that both the traditional soil radiation and material damping analytical simplifications are validated by the observed responses. It is concluded that arbitrary 'conservative' assumptions traditionally made in nuclear plant soil-structure interaction analyses are indeed arbitrary, and not born out by physical evidence. The amount of conservatism introduced by limiting total soil damping to values like 5% to 10% can be large. For the test slab sizes investigated, total soil damping is about 25%. For full size nuclear plant foundations, total soil damping is commonly in the 35% to 70% range. The authors suggest that full soil damping values (the combined radiation and material damping) should be used in the design, backfit and margin assessment of nuclear plants. (orig./HP)
Damping in building structures during earthquakes: test data and modeling
International Nuclear Information System (INIS)
Coats, D.W. Jr.
1982-01-01
A review and evaluation of the state-of-the-art of damping in building structures during earthquakes is presented. The primary emphasis is in the following areas: 1) the evaluation of commonly used mathematical techniques for incorporating damping effects in both simple and complex systems; 2) a compilation and interpretation of damping test data; and 3) an evaluation of structure testing methods, building instrumentation practices, and an investigation of rigid-body rotation effects on damping values from test data. A literature review provided the basis for evaluating mathematical techiques used to incorporate earthquake induced damping effects in simple and complex systems. A discussion on the effectiveness of damping, as a function of excitation type, is also included. Test data, from a wide range of sources, has been compiled and interpreted for buidings, nuclear power plant structures, piping, equipment, and isolated structural elements. Test methods used to determine damping and frequency parameters are discussed. In particular, the advantages and disadvantages associated with the normal mode and transfer function approaches are evaluated. Additionally, the effect of rigid-body rotations on damping values deduced from strong-motion building response records is investigated. A discussion of identification techniques typically used to determine building parameters (frequency and damping) from strong motion records is included. Finally, an analytical demonstration problem is presented to quantify the potential error in predicting fixed-base structural frequency and damping values from strong motion records, when rigid-body rotations are not properly accounted for
International Nuclear Information System (INIS)
Ware, A.G.
1986-01-01
The Idaho National Engineering Laboratory (INEL) is conducting a research program to assist the United States Nuclear Regulatory Commission (USNRC) in determining best-estimate damping values for use in the dynamic analysis of nuclear power plant piping systems. This paper describes four tasks in the program that were undertaken in FY-86. In the first task, tests were conducted on a 5-in. INEL laboratory piping system and data were analyzed from a 6-in. laboratory system at the ANCO Engineers facility to investigate the parameters influencing damping in the seismic frequency range. Further tests were conducted on 3- and 5-in. INEL laboratory piping systems as the second task to determine damping values representative of vibrations in the 33 to 100 Hz range, typical of hydrodynamic transients. In the third task a statistical evaluation of the available damping data was conduted to determine probability distributions suitable for use in probabilistic risk assessments (PRAs), and the final task evaluated damping data at high strain levels
Bryan's effect and anisotropic nonlinear damping
Joubert, Stephan V.; Shatalov, Michael Y.; Fay, Temple H.; Manzhirov, Alexander V.
2018-03-01
In 1890, G. H. Bryan discovered the following: "The vibration pattern of a revolving cylinder or bell revolves at a rate proportional to the inertial rotation rate of the cylinder or bell." We call this phenomenon Bryan's law or Bryan's effect. It is well known that any imperfections in a vibratory gyroscope (VG) affect Bryan's law and this affects the accuracy of the VG. Consequently, in this paper, we assume that all such imperfections are either minimised or eliminated by some known control method and that only damping is present within the VG. If the damping is isotropic (linear or nonlinear), then it has been recently demonstrated in this journal, using symbolic analysis, that Bryan's law remains invariant. However, it is known that linear anisotropic damping does affect Bryan's law. In this paper, we generalise Rayleigh's dissipation function so that anisotropic nonlinear damping may be introduced into the equations of motion. Using a mixture of numeric and symbolic analysis on the ODEs of motion of the VG, for anisotropic light nonlinear damping, we demonstrate (up to an approximate average), that Bryan's law is affected by any form of such damping, causing pattern drift, compromising the accuracy of the VG.
Non-Linear Slosh Damping Model Development and Validation
Yang, H. Q.; West, Jeff
2015-01-01
Propellant tank slosh dynamics are typically represented by a mechanical model of spring mass damper. This mechanical model is then included in the equation of motion of the entire vehicle for Guidance, Navigation and Control (GN&C) analysis. For a partially-filled smooth wall propellant tank, the critical damping based on classical empirical correlation is as low as 0.05%. Due to this low value of damping, propellant slosh is potential sources of disturbance critical to the stability of launch and space vehicles. It is postulated that the commonly quoted slosh damping is valid only under the linear regime where the slosh amplitude is small. With the increase of slosh amplitude, the critical damping value should also increase. If this nonlinearity can be verified and validated, the slosh stability margin can be significantly improved, and the level of conservatism maintained in the GN&C analysis can be lessened. The purpose of this study is to explore and to quantify the dependence of slosh damping with slosh amplitude. Accurately predicting the extremely low damping value of a smooth wall tank is very challenging for any Computational Fluid Dynamics (CFD) tool. One must resolve thin boundary layers near the wall and limit numerical damping to minimum. This computational study demonstrates that with proper grid resolution, CFD can indeed accurately predict the low damping physics from smooth walls under the linear regime. Comparisons of extracted damping values with experimental data for different tank sizes show very good agreements. Numerical simulations confirm that slosh damping is indeed a function of slosh amplitude. When slosh amplitude is low, the damping ratio is essentially constant, which is consistent with the empirical correlation. Once the amplitude reaches a critical value, the damping ratio becomes a linearly increasing function of the slosh amplitude. A follow-on experiment validated the developed nonlinear damping relationship. This discovery can
International Nuclear Information System (INIS)
Turner, Sam
2011-01-01
The phenomenon of process damping as a stabilising effect in milling has been encountered by machinists since milling and turning began. It is of great importance when milling aerospace alloys where maximum surface speed is limited by excessive tool wear and high speed stability lobes cannot be attained. Much of the established research into regenerative chatter and chatter avoidance has focussed on stability lobe theory with different analytical and time domain models developed to expand on the theory first developed by Trusty and Tobias. Process damping is a stabilising effect that occurs when the surface speed is low relative to the dominant natural frequency of the system and has been less successfully modelled and understood. Process damping is believed to be influenced by the interference of the relief face of the cutting tool with the waveform traced on the cut surface, with material properties and the relief geometry of the tool believed to be key factors governing performance. This study combines experimental trials with Finite Element (FE) simulation in an attempt to identify and understand the key factors influencing process damping performance in titanium milling. Rake angle, relief angle and chip thickness are the variables considered experimentally with the FE study looking at average radial and tangential forces and surface compressive stress. For the experimental study a technique is developed to identify the critical process damping wavelength as a means of measuring process damping performance. For the range of parameters studied, chip thickness is found to be the dominant factor with maximum stable parameters increased by a factor of 17 in the best case. Within the range studied, relief angle was found to have a lesser effect than expected whilst rake angle had an influence.
Fransson, Thomas; Saue, Trond; Norman, Patrick
2016-05-10
The influences of group 12 (Zn, Cd, Hg) metal-substitution on the valence spectra and phosphorescence parameters of porphyrins (P) have been investigated in a relativistic setting. In order to obtain valence spectra, this study reports the first application of the damped linear response function, or complex polarization propagator, in the four-component density functional theory framework [as formulated in Villaume et al. J. Chem. Phys. 2010 , 133 , 064105 ]. It is shown that the steep increase in the density of states as due to the inclusion of spin-orbit coupling yields only minor changes in overall computational costs involved with the solution of the set of linear response equations. Comparing single-frequency to multifrequency spectral calculations, it is noted that the number of iterations in the iterative linear equation solver per frequency grid-point decreases monotonously from 30 to 0.74 as the number of frequency points goes from one to 19. The main heavy-atom effect on the UV/vis-absorption spectra is indirect and attributed to the change of point group symmetry due to metal-substitution, and it is noted that substitutions using heavier atoms yield small red-shifts of the intense Soret-band. Concerning phosphorescence parameters, the adoption of a four-component relativistic setting enables the calculation of such properties at a linear order of response theory, and any higher-order response functions do not need to be considered-a real, conventional, form of linear response theory has been used for the calculation of these parameters. For the substituted porphyrins, electronic coupling between the lowest triplet states is strong and results in theoretical estimates of lifetimes that are sensitive to the wave function and electron density parametrization. With this in mind, we report our best estimates of the phosphorescence lifetimes to be 460, 13.8, 11.2, and 0.00155 s for H2P, ZnP, CdP, and HgP, respectively, with the corresponding transition
Magnetic damping phenomena in ferromagnetic thin-films and multilayers
Azzawi, S.; Hindmarch, A. T.; Atkinson, D.
2017-11-01
Damped ferromagnetic precession is an important mechanism underpinning the magnetisation processes in ferromagnetic materials. In thin-film ferromagnets and ferromagnetic/non-magnetic multilayers, the role of precession and damping can be critical for spintronic device functionality and as a consequence there has been significant research activity. This paper presents a review of damping in ferromagnetic thin-films and multilayers and collates the results of many experimental studies to present a coherent synthesis of the field. The terms that are used to define damping are discussed with the aim of providing consistent definitions for damping phenomena. A description of the theoretical basis of damping is presented from early developments to the latest discussions of damping in ferromagnetic thin-films and multilayers. An overview of the time and frequency domain methods used to study precessional magnetisation behaviour and damping in thin-films and multilayers is also presented. Finally, a review of the experimental observations of magnetic damping in ferromagnetic thin-films and multilayers is presented with the most recent explanations. This brings together the results from many studies and includes the effects of ferromagnetic film thickness, the effects of composition on damping in thin-film ferromagnetic alloys, the influence of non-magnetic dopants in ferromagnetic films and the effects of combining thin-film ferromagnets with various non-magnetic layers in multilayered configurations.
Shiga, Takuya; Shiraishi, Yasuyuki; Sano, Kyosuke; Taira, Yasunori; Tsuboko, Yusuke; Yamada, Akihiro; Miura, Hidekazu; Katahira, Shintaro; Akiyama, Masatoshi; Saiki, Yoshikatsu; Yambe, Tomoyuki
2016-03-01
Implantation of a total artificial heart (TAH) is one of the therapeutic options for the treatment of patients with end-stage biventricular heart failure. There is no report on the hemodynamics of the functional centrifugal-flow TAH with functional atrial contraction (fCFTAH). We evaluated the effects of pulsatile flow by atrial contraction in acute animal models. The goats received fCFTAH that we created from two centrifugal-flow ventricular assist devices. Some hemodynamic parameters maintained acceptable levels: heart rate 115.5 ± 26.3 bpm, aortic pressure 83.5 ± 10.1 mmHg, left atrial pressure 18.0 ± 5.9 mmHg, pulmonary pressure 28.5 ± 9.7 mmHg, right atrial pressure 13.6 ± 5.2 mmHg, pump flow 4.0 ± 1.1 L/min (left) 3.9 ± 1.1 L/min (right), and cardiac index 2.13 ± 0.14 L/min/m(2). fCFTAH with atrial contraction was able to maintain the TAH circulation by forming a pulsatile flow in acute animal experiments. Taking the left and right flow rate balance using the low internal pressure loss of the VAD pumps may be easier than by other pumps having considerable internal pressure loss. We showed that the remnant atrial contraction effected the flow rate change of the centrifugal pump, and the atrial contraction waves reflected the heart rate. These results indicate that remnant atria had the possibility to preserve autonomic function in fCFTAH. We may control fCFTAH by reflecting the autonomic function, which is estimated with the flow rate change of the centrifugal pump.
Magnon damping in two-dimensional Heisenberg ferromagnetic system
International Nuclear Information System (INIS)
Cheng, T.-M.; Li Lin; Ze Xianyu
2006-01-01
A magnon-phonon interaction model is set up for a two-dimensional insulating ferromagnetic system. By using Matsubara function theory we have studied the magnon damping -I m Σ* (1) (k->) and calculated the magnon damping -I m Σ* (1) (k->) curve on the main symmetric point and line in the Brillouin zone for various parameters in the system. It is concluded that at the boundary of Brillouin zone there is a strong magnon damping. However, the magnon damping is very weak on the zone of small wave vector and the magnon damping reaches maximal value at very low temperature. The contributions of longitudinal phonon and transverse phonon on the magnon damping are compared and the influences of various parameters are also discussed
Collisional damping of Langmuir waves in the collisionless limit
International Nuclear Information System (INIS)
Auerbach, S.P.
1977-01-01
Linear Langmuir wave damping by collisions is studied in the limit of collision frequency ν approaching zero. In this limit, collisions are negligible, except in a region in velocity space, the boundary layer, centered about the phase velocity. If kappa, the ratio of the collisional equilibration time in the boundary layer to the Landau damping time, is small, the boundary layer width scales as ν/sup 1/3/, and the perturbed distribution function scales as ν/sup -1/3/. The damping rate is thus independent of ν, although essentially all the damping occurs in the collision-dominated boundary layer. Solution of the Fokker--Planck equation shows that the damping rate is precisely the Landau (collisionless) rate. The damping rate is independent of kappa, although the boundary layer thickness is not
Directory of Open Access Journals (Sweden)
Tai-Hong Cheng
2015-01-01
Full Text Available Composite materials are increasingly used in wind blade because of their superior mechanical properties such as high strength-to-weight and stiffness-to-weight ratio. This paper presents vibration and damping analysis of fiberreinforced composite wind turbine blade with viscoelastic damping treatment. The finite element method based on full layerwise displacement theory was employed to analyze the damping, natural frequency, and modal loss factor of composite shell structure. The lamination angle was considered in mathematical modeling. The curved geometry, transverse shear, and normal strains were exactly considered in present layerwise shell model, which can depict the zig-zag in-plane and out-of-plane displacements. The frequency response functions of curved composite shell structure and wind blade were calculated. The results show that the damping ratio of viscoelastic layer is found to be very sensitive to determination of magnitude of composite structures. The frequency response functions with variety of thickness of damping layer were investigated. Moreover, the natural frequency, modal loss factor, and mode shapes of composite fiber reinforced wind blade with viscoelastic damping control were calculated.
Exponential decay for solutions to semilinear damped wave equation
Gerbi, Stéphane
2011-10-01
This paper is concerned with decay estimate of solutions to the semilinear wave equation with strong damping in a bounded domain. Intro- ducing an appropriate Lyapunov function, we prove that when the damping is linear, we can find initial data, for which the solution decays exponentially. This result improves an early one in [4].
Damping of Coherent oscillations
Vos, L
1996-01-01
Damping of coherent oscillations by feedback is straightforward in principle. It has been a vital ingredient for the safe operation of accelerators since a long time. The increasing dimensions and beam intensities of the new generation of hadron colliders impose unprecedented demands on the performance of future systems. The arguments leading to the specification of a transverse feedback system for the CERN SPS in its role as LHC injector and the LHC collider itself are developped to illustrate this. The preservation of the transverse emittance is the guiding principle during this exercise keeping in mind the hostile environment which comprises: transverse impedance bent on developping coupled bunch instabilities, injection errors, unwanted transverse excitation, unavoidable tune spreads and noise in the damping loop.
International Nuclear Information System (INIS)
Shibata, H.; Ito, A.; Tanaka, K.; Niino, T.; Gotoh, N.
1981-01-01
Generally, damping phenomena of structures and equipments is caused by very complex energy dissipation. Especially, as piping systems are composed of many components, it is very difficult to evaluate damping characteristics of its system theoretically. On the other hand, the damping value for aseismic design of nuclear power plants is very important design factor to decide seismic response loads of structures, equipments and piping systems. The very extensive studies titled SDREP (Seismic Damping Ratio Evaluation Program) were performed to establish proper damping values for seismic design of piping as a joint work among a university, electric companies and plant makers. In SDREP, various systematic vibration tests were conducted to investigate factors which may contribute to damping characteristics of piping systems and to supplement the data of the pre-operating tests. This study is related to the component damping characteristics tests of that program. The object of this study is to clarify damping characteristics and mechanism of hanger supports used in piping systems, and to establish the evaluation technique of dispersing energy at hanger support points and its effect to the total damping ability of piping system. (orig./WL)
Dislocation damping during irradiation
International Nuclear Information System (INIS)
Burdett, C.F.; Rahmatalla, H.
1977-01-01
The results of Simpson et al (Simpson, H.M., Sosin, A., Johnston, D.F., Phys.Rev. B, 5:1393 (1972)) on the damping produced during electron irradiation of copper are re-examined and it is shown that they can be explained in terms of the model of Granato and Lucke (Granato, A., Lucke, K., J.Appl.Phys., 27:583,789 (1958)). (author)
Minimum wakefield achievable by waveguide damped cavity
International Nuclear Information System (INIS)
Lin, X.E.; Kroll, N.M.
1995-01-01
The authors use an equivalent circuit to model a waveguide damped cavity. Both exponentially damped and persistent (decay t -3/2 ) components of the wakefield are derived from this model. The result shows that for a cavity with resonant frequency a fixed interval above waveguide cutoff, the persistent wakefield amplitude is inversely proportional to the external Q value of the damped mode. The competition of the two terms results in an optimal Q value, which gives a minimum wakefield as a function of the distance behind the source particle. The minimum wakefield increases when the resonant frequency approaches the waveguide cutoff. The results agree very well with computer simulation on a real cavity-waveguide system
BNS damping of beam breakup instability
International Nuclear Information System (INIS)
Stupakov, G.V.
1997-08-01
The author studies BNS damping of the beam breakup instability in a simple model assuming a constant beam energy, flat bunch distribution, and a smooth transverse focusing. The model allows an analytic solution for a constant and linear wake functions. Scaling dimensionless parameters are derived and the beam dynamics is illustrated for the range of parameters relevant to the Stanford Linear Collider
On small vibrations of a damped Stieltjes string
Directory of Open Access Journals (Sweden)
Olga Boyko
2015-01-01
Full Text Available Inverse problem of recovering masses, coefficients of damping and lengths of the intervals between the masses using two spectra of boundary value problems and the total length of the Stieltjes string (an elastic thread bearing point masses is considered. For the case of point-wise damping at the first counting from the right end mass the problem of recovering the masses, the damping coefficient and the lengths of the subintervals by one spectrum and the total length of the string is solved.
Damping measurements in flowing water
Coutu, A.; Seeley, C.; Monette, C.; Nennemann, B.; Marmont, H.
2012-11-01
Fluid-structure interaction (FSI), in the form of mass loading and damping, governs the dynamic response of water turbines, such as Francis turbines. Water added mass and damping are both critical quantities in evaluating the dynamic response of the turbine component. Although the effect of fluid added mass is well documented, fluid damping, a critical quantity to limit vibration amplitudes during service, and therefore to help avoiding possible failure of the turbines, has received much less attention in the literature. This paper presents an experimental investigation of damping due to FSI. The experimental setup, designed to create dynamic characteristics similar to the ones of Francis turbine blades is discussed, together with the experimental protocol and examples of measurements obtained. The paper concludes with the calculated damping values and a discussion on the impact of the observed damping behaviour on the response of hydraulic turbine blades to FSI.
Damping measurements in flowing water
International Nuclear Information System (INIS)
Coutu, A; Monette, C; Nennemann, B; Marmont, H; Seeley, C
2012-01-01
Fluid-structure interaction (FSI), in the form of mass loading and damping, governs the dynamic response of water turbines, such as Francis turbines. Water added mass and damping are both critical quantities in evaluating the dynamic response of the turbine component. Although the effect of fluid added mass is well documented, fluid damping, a critical quantity to limit vibration amplitudes during service, and therefore to help avoiding possible failure of the turbines, has received much less attention in the literature. This paper presents an experimental investigation of damping due to FSI. The experimental setup, designed to create dynamic characteristics similar to the ones of Francis turbine blades is discussed, together with the experimental protocol and examples of measurements obtained. The paper concludes with the calculated damping values and a discussion on the impact of the observed damping behaviour on the response of hydraulic turbine blades to FSI.
Variation in Differential and Total Cross Sections Due to Different Radial Wave Functions
Williamson, W., Jr.; Greene, T.
1976-01-01
Three sets of analytical wave functions are used to calculate the Na (3s---3p) transition differential and total electron excitation cross sections by Born approximations. Results show expected large variations in values. (Author/CP)
Dynamic response analysis of a 24-story damped steel structure
Feng, Demin; Miyama, Takafumi
2017-10-01
In Japanese and Chinese building codes, a two-stage design philosophy, damage limitation (small earthquake, Level 1) and life safety (extreme large earthquake, Level 2), is adopted. It is very interesting to compare the design method of a damped structure based on the two building codes. In the Chinese code, in order to be consistent with the conventional seismic design method, the damped structure is also designed at the small earthquake level. The effect of damper systems is considered by the additional damping ratio concept. The design force will be obtained from the damped design spectrum considering the reduction due to the additional damping ratio. The additional damping ratio by the damper system is usually calculated by a time history analysis method at the small earthquake level. The velocity dependent type dampers such as viscous dampers can function well even in the small earthquake level. But, if steel damper is used, which usually remains elastic in the small earthquake, there will be no additional damping ratio achieved. On the other hand, a time history analysis is used in Japan both for small earthquake and extreme large earthquake level. The characteristics of damper system and ductility of the structure can be modelled well. An existing 24-story steel frame is modified to demonstrate the design process of the damped structure based on the two building codes. Viscous wall type damper and low yield steel panel dampers are studied as the damper system.
The DAMPE silicon–tungsten tracker
Energy Technology Data Exchange (ETDEWEB)
Azzarello, P., E-mail: philipp.azzarello@unige.ch [Département de Physique Nucléaire et Corpusculaire, University of Geneva, Geneva (Switzerland); Ambrosi, G. [Istituto Nazionale di Fisica Nucleare Sezione di Perugia, Perugia (Italy); Asfandiyarov, R. [Département de Physique Nucléaire et Corpusculaire, University of Geneva, Geneva (Switzerland); Bernardini, P. [Dipartimento di Matematica e Fisica “E. De Giorgi”, Università del Salento, Lecce (Italy); Istituto Nazionale di Fisica Nucleare Sezione di Lecce, Lecce (Italy); Bertucci, B.; Bolognini, A. [Istituto Nazionale di Fisica Nucleare Sezione di Perugia, Perugia (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, Perugia (Italy); Cadoux, F. [Département de Physique Nucléaire et Corpusculaire, University of Geneva, Geneva (Switzerland); Caprai, M. [Istituto Nazionale di Fisica Nucleare Sezione di Perugia, Perugia (Italy); De Mitri, I. [Dipartimento di Matematica e Fisica “E. De Giorgi”, Università del Salento, Lecce (Italy); Istituto Nazionale di Fisica Nucleare Sezione di Lecce, Lecce (Italy); Domenjoz, M. [Département de Physique Nucléaire et Corpusculaire, University of Geneva, Geneva (Switzerland); Dong, Y. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing (China); Duranti, M. [Istituto Nazionale di Fisica Nucleare Sezione di Perugia, Perugia (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, Perugia (Italy); Fan, R. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing (China); and others
2016-09-21
The DArk Matter Particle Explorer (DAMPE) is a spaceborne astroparticle physics experiment, launched on 17 December 2015. DAMPE will identify possible dark matter signatures by detecting electrons and photons in the 5 GeV–10 TeV energy range. It will also measure the flux of nuclei up to 100 TeV, for the study of the high energy cosmic ray origin and propagation mechanisms. DAMPE is composed of four sub-detectors: a plastic strip scintillator, a silicon–tungsten tracker–converter (STK), a BGO imaging calorimeter and a neutron detector. The STK is composed of six tracking planes of 2 orthogonal layers of single-sided micro-strip detectors, for a total detector surface of ca. 7 m{sup 2}. The STK has been extensively tested for space qualification. Also, numerous beam tests at CERN have been done to study particle detection at silicon module level, and at full detector level. After description of the DAMPE payload and its scientific mission, we will describe the STK characteristics and assembly. We will then focus on some results of single ladder performance tests done with particle beams at CERN.
An Approximate Method for Pitch-Damping Prediction
National Research Council Canada - National Science Library
Danberg, James
2003-01-01
...) method for predicting the pitch-damping coefficients has been employed. The CFD method provides important details necessary to derive the correlation functions that are unavailable from the current experimental database...
A Note on Using Unbounded Functions on Totally Bounded Sets in ...
African Journals Online (AJOL)
From a real-valued function f, unbounded on a totally bounded subset of a metric space, we construct a Cauchy sequence in S on which f is unbounded. Taking f to be a reciprocal Lebesgue number function, for an open cover of S, gives a rapid proof that S is compact when it is complete, without recourse to ...
Male sexual function and lower urinary tract symptoms after laparoscopic total mesorectal excision
Breukink, S. O.; Driel, M. F. van; Pierie, J. P. E. N.; Dobbins, C.; Wiggers, T.; Meijerink, W. J. H. J.
2008-01-01
The aim of this study was to investigate sexual function and the presence of lower urinary tract symptoms (LUTS) in male patients with rectal cancer following short-term radiotherapy and laparoscopic total mesorectal excision (LTME) by physical and psychological measurements. Sexual function and
Total-dielectric-function approach to electron and phonon response in solids
International Nuclear Information System (INIS)
Penn, D.R.; Lewis, S.P.; Cohen, M.L.
1995-01-01
The interaction between two test charges, the response of a solid to an external field, and the normal modes of the solid can be determined from a total dielectric function that includes both electronic and lattice polarizabilities as well as local-field effects. In this paper we examine the relationship between superconductivity and the stability of a solid and derive sum rules for the electronic part of the dielectric function. It is also shown that there are negative eigenvalues of the total static dielectric function, implying the possibility of an attractive interaction between test charges. An attractive interaction is required for superconductivity
Effect of pre-operative neuromuscular training on functional outcome after total knee replacement
DEFF Research Database (Denmark)
Huber, Erika O; de Bie, Rob A; Roos, Ewa M.
2013-01-01
Total Knee Replacement (TKR) is the standard treatment for patients with severe knee osteoarthritis (OA). Significant improvement in pain and function are seen after TKR and approximately 80% of patients are very satisfied with the outcome. Functional status prior to TKR is a major predictor...... of outcome after the intervention. Thus, improving functional status prior to surgery through exercise may improve after surgery outcome. However, results from several previous trials testing the concept have been inconclusive after surgery....
Harris functional and related methods for calculating total energies in density-functional theory
International Nuclear Information System (INIS)
Averill, F.W.; Painter, G.S.
1990-01-01
The simplified energy functional of Harris has given results of useful accuracy for systems well outside the limits of weakly interacting fragments for which the method was originally proposed. In the present study, we discuss the source of the frequent good agreement of the Harris energy with full Kohn-Sham self-consistent results. A procedure is described for extending the applicability of the scheme to more strongly interacting systems by going beyond the frozen-atom fragment approximation. A gradient-force expression is derived, based on the Harris functional, which accounts for errors in the fragment charge representation. Results are presented for some diatomic molecules, illustrating the points of this study
Hershkovitz, Avital; Vesilkov, Marina; Beloosesky, Yichayaou; Brill, Shai
2017-01-10
Total joint arthroplasty (TJA) is an effective and successful treatment of osteoarthritis of the hip and knee as quantified by several measures, such as pain relief, improved walking, improved self-care, functions, and increased quality of life. Data are lacking as to the definition of a satisfactory functional gain in a postacute setting and identifying the characteristics of older patients with TJA who may achieve that gain. Our aim was to characterize patients who may achieve a satisfactory functional gain in a postacute rehabilitation setting following TJA. This was a retrospective study of 180 patients with TJA admitted during 2010-2013. The main outcome measures were the Functional Independence Measure (FIM), the Montebello Rehabilitation Factor Score (MRFS) on the motor FIM, and the Timed Get Up and Go Test. Satisfactory functional gain was defined as an mFIM MRFS score above median score. Comparisons of clinical and demographic characteristics between patients who achieved a satisfactory functional gain versus those who did not were performed by the Mann-Whitney U test and the χ test. The proportion of patients who achieved a satisfactory functional gain was similar in the total knee arthroplasty and total hip arthroplasty (THA) groups. The most significant characteristic of patients who achieved a satisfactory functional gain was their admission functional ability. Age negatively impacted the ability to achieve a satisfactory functional gain in patients with THA. Functional level on admission is the best predictive factor for a better rehabilitation outcome for patients with TJA. Age negatively affects functional gain in patients with THA.
The influence of optimism on functionality after total hip replacement surgery.
Balck, Friedrich; Lippmann, Maike; Jeszenszky, Csilla; Günther, Klaus-Peter; Kirschner, Stephan
2016-08-01
Among other factors, optimism has been shown to significantly influence the course of some diseases (cancer, HIV, coronary heart disease). This study investigated whether optimism of a patient before a total hip replacement can predict the functionality of the lower limbs 3 and 6 months after surgery. A total of 325 patients took part in the study (age: 58.7 years; w: 55%). The functionality was measured with the Western Ontario and McMaster Universities arthrosis index, and optimism with the Life Orientation Test. To analyse the influences of age, gender and optimism, general linear models were calculated. In optimistic patients, functionality improved significantly over time. The study showed a clear influence of dispositional optimism on the recovery after total hip replacement in the first 3 months after surgery. © The Author(s) 2015.
A simple functional form for proton-208Pb total reaction cross sections
International Nuclear Information System (INIS)
Majumdar, S.; Deb, P.K.; Amos, K.
2001-01-01
A simple functional form has been found that gives a good representation of the total reaction cross sections for the scattering from 208 Pb of protons with energies in the range 30 to 300 MeV. The ratios of the total reaction cross sections calculated under this approximations compared well (to within a few percent) to those determined from the microscopic optical model potentials
International Nuclear Information System (INIS)
Anderson, M.J.; Barta, D.A.; Lindquist, M.R.; Renkey, E.J.; Ryan, J.A.
1983-06-01
LMFBR pipe systems typically utilize a thicker insulation package than that used on water plant pipe systems. They are supported with special insulated pipe clamps. Mechanical snubbers are employed to resist seismic loads. Recent laboratory testing has indicated that these features provide significantly more damping than presently allowed by Regulatory Guide 1.61 for water plant pipe systems. This paper presents results of additional in-situ vibration tests conducted on FFTF pipe systems. Pipe damping values obtained at various excitation levels are presented. Effects of filtering data to provide damping values at discrete frequencies and the alternate use of a single equivalent modal damping value are discussed. These tests further confirm that damping in typical LMFBR pipe systems is larger than presently used in pipe design. Although some increase in damping occurred with increased excitation amplitude, the effect was not significant. Recommendations are made to use an increased damping value for both the OBE and DBE seismic events in design of LMFBR pipe systems
Impedance calculations for the improved SLC damping rings
International Nuclear Information System (INIS)
Bane, K.L.F.; Ng, C.K.
1993-04-01
A longitudinal, single bunch instability is observed in the damping rings of the Stanford Linear Collider (SLC). Beyond a threshold bunch population of 3 x 10 10 particles the bunch energy spread increases and a ''saw-tooth'' variation in bunch length and synchronous phase as functions of time is observed. Although the relative amplitude of the saw-tooth variation is small-only on the order of 10% -- the resulting unpredictability of the beam properties in the rest of the SLC accelerator makes it difficult, if not impossible, to operate the machine above the threshold current. An additional problem at higher currents is that the bunch length is greatly increased. When the bunch is very long in the ring it becomes difficult or impossible to properly compress it after extraction. We want to solve both of these problems so that the SLC can run at higher currents to increase the luminosity. In order to solve these problems the vacuum chambers of both damping rings are being rebuilt with the aim of reducing their impedance. According to previous calculations the impedance the SLC damping rings is dominated by the many small discontinuities that are located in the so-called QD and QF vacuum chamber segments -- elements such as transitions, masks, bellows-that are inductive to the beam, Since these earlier calculations were performed the bellows of the QD segments have been sleeved, yielding a factor of 2 increase in the instability threshold. In this paper we begin by discussing the gains that might be achieved if we can reduce the impedance of the rings even further. Then we estimate the effect on the total impedance of the actual design changes that are being proposed. Three important elements -- the bend-to-quad transitions, the distributed ion pump slots, and the beam position monitor (BPM) electrodes are fully 3-dimensional and will be studied using T3 of the MAFIA computer programs
International Nuclear Information System (INIS)
Skibin, D.
1980-01-01
A general case of release to the atmosphere of a pollutant is considered. In hazards evaluation the processes involved are usually estimated conservatively so as to maximize the computed doses. The present work helps to identify the worst cases. In addition, a model of the total dose is presented and its variations are studied as a function of wind speed, deposition velocity and source height. The value of each parameter giving the highest total dose as a function of the model's parameters is determined. (H.K.)
Etiology of root parsley damping-off
Directory of Open Access Journals (Sweden)
Bogdan Nowicki
2013-12-01
Full Text Available The investigations were done between 1990-1994. Seedlings collected from 120 plantations were evaluated. The fungi responsible for seedling damping-off occurrening most often were Alternariu spp., Fusarium spp. and Pythium spp. isolated from 46,3, 32,2 and 16,6% of infected plants, respectively. The most important pathogens were A.petroselini which infected 33% of seedlings and A.radicina - 11%„ Among Fusarium species the most common was F.avenaceum, comprising 61% of total Fusarium isolates. The next were following: F.culmorum - 21%, F.solani - 12,6% and 3% for both F.equiseti and F.oxysporum. Damping-off of se,edlings was also caused by the other fungi but they were noted in low intensity. Among them were following: Phoma spp., A.alternata and Rhizoctonia solani on 2,8; 2,3 and 1,2% of tested seedlings. respectively. The species: Sclerotinia sclerotiorum, Botrytis cinerea, Bipolaris sorokinianu and Septoria petroselini were isolated in total from 0,9% of seedlings. Drechslera biseptata and Stemphylium botryosum caused seedling damping-off sporadically.
The total cross section as a function of energy for elastic scattering of noble gas atoms
International Nuclear Information System (INIS)
Linse, C.A.
1978-01-01
Precise relative measurements of the total cross-sections as a function of velocity is presented for the systems Ar-Ar, Ar-Kr, Kr-Ar, Ar-Xe, Ne-Ar, Ne-Kr, and Ne-Xe, the primary beam particle being mentioned first. A discription of the apparatus is given. Then the method for extracting total cross-sections from the measured beam attenuation is analyzed. A comparison is made with total cross-sections calculated from various potentials that have been proposed in the literature
International Nuclear Information System (INIS)
Bullock, J.C.; Kelley, B.E.
1977-01-01
A valve for damping out flow surges in a vacuum system is described. The surge-damping mechanism consists of a slotted, spring-loaded disk adjacent to the valve's vacuum port (the flow passage to the vacuum roughing pump). Under flow surge conditions, the differential pressure forces the disk into a sealing engagement with the vacuum port, thereby restricting the gas flow path to narrow slots in the disk's periphery. The increased flow damps out the flow surge. When pressure is equalized on both sides of the valve, the spring load moves the disk away from the port to restore full flow conductance through the valve
Damping Identification of Bridges Under Nonstationary Ambient Vibration
Directory of Open Access Journals (Sweden)
Sunjoong Kim
2017-12-01
Full Text Available This research focuses on identifying the damping ratio of bridges using nonstationary ambient vibration data. The damping ratios of bridges in service have generally been identified using operational modal analysis (OMA based on a stationary white noise assumption for input signals. However, most bridges are generally subjected to nonstationary excitations while in service, and this violation of the basic assumption can lead to uncertainties in damping identification. To deal with nonstationarity, an amplitude-modulating function was calculated from measured responses to eliminate global trends caused by nonstationary input. A natural excitation technique (NExT-eigensystem realization algorithm (ERA was applied to estimate the damping ratio for a stationarized process. To improve the accuracy of OMA-based damping estimates, a comparative analysis was performed between an extracted stationary process and nonstationary data to assess the effect of eliminating nonstationarity. The mean value and standard deviation of the damping ratio for the first vertical mode decreased after signal stationarization. Keywords: Damping, Operational modal analysis, Traffic-induced vibration, Nonstationary, Signal stationarization, Amplitude-modulating, Bridge, Cable-stayed, Suspension
Totally Optimal Decision Trees for Monotone Boolean Functions with at Most Five Variables
Chikalov, Igor
2013-01-01
In this paper, we present the empirical results for relationships between time (depth) and space (number of nodes) complexity of decision trees computing monotone Boolean functions, with at most five variables. We use Dagger (a tool for optimization of decision trees and decision rules) to conduct experiments. We show that, for each monotone Boolean function with at most five variables, there exists a totally optimal decision tree which is optimal with respect to both depth and number of nodes.
Comparative responsiveness of measures of pain and function after total hip replacement
DEFF Research Database (Denmark)
Nilsdotter, A K; Roos, Ewa M.; Westerlund, J P
2001-01-01
To compare the responsiveness of the Functional Assessment System (FAS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Medical Outcomes Study 36-item Short Form (SF-36) in patients with osteoarthritis (OA) scheduled for total hip replacement....
Evaluation of the Function and Quality of Life after Total Hip Arthroplasty by Different Approaches
Directory of Open Access Journals (Sweden)
Paulo Araújo
2017-09-01
Conclusion: After 24 months post total hip arthroplasty there are no differences between the two approaches with regard to function or quality of life. However, the patients operated by the anterolateral approach had greater muscle strength deficits and higher percentage of positive Trendelenburg test.
Lower Limbs Function and Pain Relationships after Unilateral Total Knee Arthroplasty
Tali, Maie; Maaroos, Jaak
2010-01-01
The aim of the study was to evaluate gait characteristics, lower limbs joint function, and pain relationships associated with knee osteoarthritis of female patients before and 3 months after total knee arthroplasty at an outpatient clinic rehabilitation department. Gait parameters were registered, the active range of lower extremity joints was…
Orbital and total atomic momentum expectation values with Roothaan-Hartree-Fock wave functions
International Nuclear Information System (INIS)
De La Vega, J.M.G.; Miguel, B.
1993-01-01
Orbital and total momentum expectation values are computed using the Roothaan-Hartree-Fock wave functions of Clementi and Roetti. These values are calculated analytically and may be used to study the quality of basis sets. Tabulations for ground and excited states of atoms from Z = 2 to Z = 54 are presented. 23 refs., 1 tab
Quality of Life after Total Laryngectomy: Functioning, Psychological Well-Being and Self-Efficacy
Perry, Alison; Casey, Erica; Cotton, Sue
2015-01-01
Background: Quality of life (QoL) is an important construct when assessing treatment outcomes. Aims: To examine the relative contributions of functioning, psychological well-being and self-efficacy on self-perceived QoL with a sample of total laryngectomy patients in Australia who had surgery for advanced laryngeal cancer. Methods &…
Multi-Product Total Cost of Function for Higher Education: A Case of Bible Colleges.
Koshal, Rajindar K.; Koshal, Manjulika; Gupta, Ashok
2001-01-01
This study empirically estimates a multiproduct total cost function and output relationship for comprehensive U.S. universities. Statistical results for 184 Bible colleges suggest that there are both economies of scale and of scope in higher education. Additionally, product-specific economies of scope exist for all output levels and activities.…
Functional exercise after total hip replacement (FEATHER): a randomised control trial.
LENUS (Irish Health Repository)
Monaghan, Brenda
2012-11-01
Prolonged physical impairments in range of movement, postural stability and walking speed are commonly reported following total hip replacement (THR). It is unclear from the current body of evidence what kind of exercises should be performed to maximize patient function and quality of life.
KPII: Cauchy-Jost function, Darboux transformations and totally nonnegative matrices
Boiti, M.; Pempinelli, F.; Pogrebkov, A. K.
2017-07-01
Direct definition of the Cauchy-Jost (known also as Cauchy-Baker-Akhiezer) function is given in the case of a pure solitonic solution. Properties of this function are discussed in detail using the Kadomtsev-Petviashvili II equation as an example. This enables formulation of the Darboux transformations in terms of the Cauchy-Jost function and classification of these transformations. Action of Darboux transformations on Grassmanians—i.e. on the space of soliton parameters—is derived and the relation of the Darboux transformations with the property of total nonnegativity of elements of corresponding Grassmanians is discussed. To the memory of our friend and colleague Peter P Kulish
Damping in aerospace composite materials
Agneni, A.; Balis Crema, L.; Castellani, A.
Experimental results are presented on specimens of carbon and Kevlar fibers in epoxy resin, materials used in many aerospace structures (control surfaces and wings in aircraft, large antennas in spacecraft, etc.). Some experimental methods of estimating damping ratios are first reviewed, either in the time domain or in the frequency domain. Some damping factor estimates from experimental tests are then shown; in order to evaluate the effects of the aerospace environment, damping factors have been obtained in a typical range of temperature, namely between +120 C and -120 C, and in the pressure range from room pressure to 10 exp -6 torr. Finally, a theoretical approach for predicting the bounds of the damping coefficients is shown, and prediction data are compared with experimental results.
Amplitude damping of vortex modes
CSIR Research Space (South Africa)
Dudley, Angela L
2010-09-01
Full Text Available An interferometer, mimicking an amplitude damping channel for vortex modes, is presented. Experimentally the action of the channel is in good agreement with that predicted theoretically. Since we can characterize the action of the channel on orbital...
Emittance damping considerations for TESLA
International Nuclear Information System (INIS)
Floettmann, K.; Rossbach, J.
1993-03-01
Two schemes are considered to avoid very large damping rings for TESLA. The first (by K.F.) makes use of the linac tunnel to accomodate most of the damping 'ring' structure, which is, in fact, not a ring any more but a long linear structure with two small bends at each of its ends ('dog-bone'). The other scheme (by J.R.) is based on a positron (or electron, respectively) recycling scheme. It makes use of the specific TESLA property, that the full bunch train is much longer (240 km) than the linac length. The spent beams are recycled seven times after interaction, thus reducing the number of bunches to be stored in the damping ring by a factor of eight. Ultimately, this scheme can be used to operate TESLA in a storage ring mode ('storage linac'), with no damping ring at all. Finally, a combination of both schemes is considered. (orig.)
Barotropic FRW cosmologies with Chiellini damping
Energy Technology Data Exchange (ETDEWEB)
Rosu, Haret C., E-mail: hcr@ipicyt.edu.mx [IPICyT, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San José 2055, Col. Lomas 4a Sección, 78216 San Luis Potosí, SLP (Mexico); Mancas, Stefan C., E-mail: stefan.mancas@erau.edu [Department of Mathematics, Embry–Riddle Aeronautical University, Daytona Beach, FL 32114-3900 (United States); Chen, Pisin, E-mail: pisinchen@phys.ntu.edu.tw [Leung Center for Cosmology and Particle Astrophysics (LeCosPA) and Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China)
2015-05-08
It is known that barotropic FRW equations written in the conformal time variable can be reduced to simple linear equations for an exponential function involving the conformal Hubble rate. Here, we show that an interesting class of barotropic universes can be obtained in the linear limit of a special type of nonlinear dissipative Ermakov–Pinney equations with the nonlinear dissipation built from Chiellini's integrability condition. These cosmologies, which evolutionary are similar to the standard ones, correspond to barotropic fluids with adiabatic indices rescaled by a particular factor and have amplitudes of the scale factors inverse proportional to the adiabatic index. - Highlights: • Chiellini-damped Ermakov–Pinney equations are used in barotropic FRW cosmological context. • Chiellini-damped scale factors of the barotropic FRW universes are introduced. • These scale factors are similar to the undamped ones.
Landau damping in trapped Bose condensed gases
Energy Technology Data Exchange (ETDEWEB)
Jackson, B; Zaremba, E [Department of Physics, Queen' s University, Kingston, ON K7L 3N6 (Canada)
2003-07-01
We study Landau damping in dilute Bose-Einstein condensed gases in both spherical and prolate ellipsoidal harmonic traps. We solve the Bogoliubov equations for the mode spectrum in both of these cases, and calculate the damping by summing over transitions between excited quasiparticle states. The results for the spherical case are compared to those obtained in the Hartree-Fock (HF) approximation, where the excitations take on a single-particle character, and excellent agreement between the two approaches is found. We have also taken the semiclassical limit of the HF approximation and obtain a novel expression for the Landau damping rate involving the time-dependent self-diffusion function of the thermal cloud. As a final approach, we study the decay of a condensate mode by making use of dynamical simulations in which both the condensate and thermal cloud are evolved explicitly as a function of time. A detailed comparison of all these methods over a wide range of sample sizes and trap geometries is presented.
Feng, Jun-Tao; Liu, Han-Qiu; Xu, Jian-Guang; Gu, Yu-Dong; Shen, Yun-Dong
2015-09-01
Total brachial plexus avulsion injury (BPAI) results in the total functional loss of the affected limb and induces extensive brain functional reorganization. However, because the dominant hand is responsible for more cognitive-related tasks, injuries on this side induce more adaptive changes in brain function. In this article, we explored the differences in brain functional reorganization after injuries in unilateral BPAI patients. We applied resting-state functional magnetic resonance imaging scanning to 10 left and 10 right BPAI patients and 20 healthy control subjects. The amplitude of low-frequency fluctuation (ALFF), which is a resting-state index, was calculated for all patients as an indication of the functional activity level of the brain. Two-sample t-tests were performed between left BPAI patients and controls, right BPAI patients and controls, and between left and right BPAI patients. Two-sample t-tests of the ALFF values revealed that right BPAIs induced larger scale brain reorganization than did left BPAIs. Both left and right BPAIs elicited a decreased ALFF value in the right precuneus (P right BPAI patients exhibited increased ALFF values in a greater number of brain regions than left BPAI patients, including the inferior temporal gyrus, lingual gyrus, calcarine sulcus, and fusiform gyrus. Our results revealed that right BPAIs induced greater extents of brain functional reorganization than left BPAIs, which reflected the relatively more extensive adaptive process that followed injuries of the dominant hand. Copyright © 2015 Elsevier Inc. All rights reserved.
Vibration damping method and apparatus
Redmond, James M.; Barney, Patrick S.; Parker, Gordon G.; Smith, David A.
1999-01-01
The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof.
Damping Measurements of Plasma Modes
Anderegg, F.; Affolter, M.; Driscoll, C. F.
2010-11-01
For azimuthally symmetric plasma modes in a magnesium ion plasma, confined in a 3 Tesla Penning-Malmberg trap with a density of n ˜10^7cm-3, we measure a damping rate of 2s-1plasma column, alters the frequency of the mode from 16 KHz to 192 KHz. The oscillatory fluid displacement is small compared to the wavelength of the mode; in contrast, the fluid velocity, δvf, can be large compared to v. The real part of the frequency satisfies a linear dispersion relation. In long thin plasmas (α> 10) these modes are Trivelpiece-Gould (TG) modes, and for smaller values of α they are Dubin spheroidal modes. However the damping appears to be non-linear; initially large waves have weaker exponential damping, which is not yet understood. Recent theoryootnotetextM.W. Anderson and T.M. O'Neil, Phys. Plasmas 14, 112110 (2007). calculates the damping of TG modes expected from viscosity due to ion-ion collisions; but the measured damping, while having a similar temperature and density dependence, is about 40 times larger than calculated. This discrepancy might be due to an external damping mechanism.
Multi-damping earthquake design spectra-compatible motion histories
International Nuclear Information System (INIS)
Choi, Dong-Ho; Lee, Sang-Hoon
2003-01-01
Two iterative methods of developing time histories compatible with multi-damping spectra are presented. The common method of forcing agreement among design and calculated spectral values at several frequencies and multiple damping values may give poor, even meaningless results. The two simple iterative techniques presented here use acceleration impulse functions for 'correcting' the time histories. In the first method the correction is calculated separately for each frequency and damping value and the maximum corresponding coefficient is used to correct the time history for the iteration. In the second method the solution is further improved by introducing a scale factor at each iteration. The effectiveness of the proposed techniques is illustrated by a comparison of a set of six multi-damping design spectra with spectral responses of a time history
Mooring Line Damping Estimation for a Floating Wind Turbine
Directory of Open Access Journals (Sweden)
Dongsheng Qiao
2014-01-01
Full Text Available The dynamic responses of mooring line serve important functions in the station keeping of a floating wind turbine (FWT. Mooring line damping significantly influences the global motions of a FWT. This study investigates the estimation of mooring line damping on the basis of the National Renewable Energy Laboratory 5 MW offshore wind turbine model that is mounted on the ITI Energy barge. A numerical estimation method is derived from the energy absorption of a mooring line resulting from FWT motion. The method is validated by performing a 1/80 scale model test. Different parameter changes are analyzed for mooring line damping induced by horizontal and vertical motions. These parameters include excitation amplitude, excitation period, and drag coefficient. Results suggest that mooring line damping must be carefully considered in the FWT design.
Mooring line damping estimation for a floating wind turbine.
Qiao, Dongsheng; Ou, Jinping
2014-01-01
The dynamic responses of mooring line serve important functions in the station keeping of a floating wind turbine (FWT). Mooring line damping significantly influences the global motions of a FWT. This study investigates the estimation of mooring line damping on the basis of the National Renewable Energy Laboratory 5 MW offshore wind turbine model that is mounted on the ITI Energy barge. A numerical estimation method is derived from the energy absorption of a mooring line resulting from FWT motion. The method is validated by performing a 1/80 scale model test. Different parameter changes are analyzed for mooring line damping induced by horizontal and vertical motions. These parameters include excitation amplitude, excitation period, and drag coefficient. Results suggest that mooring line damping must be carefully considered in the FWT design.
Thermodynamic Damping in Porous Materials with Spherical Cavities
Directory of Open Access Journals (Sweden)
Sofia D. Panteliou
1997-01-01
Full Text Available When a material is subjected to an alternating stress field, there are temperature fluctuations throughout its volume due to the thermoelastic effect. The resulting irreversible heat conduction leads to entropy production that in turn is the cause of thermoelastic damping. An analytical investigation of the entropy produced during a vibration cycle due to the reciprocity of temperature rise and strain yielded the change of the material damping factor as a function of the porosity of the material. A homogeneous, isotropic, elastic bar of cylindrical shape is considered with uniformly distributed spherical cavities under alternating uniform axial stress. The analytical calculation of the dynamic characteristics of the porous structure yielded the damping factor of the bar and the material damping factor. Exsperimental results on porous metals are in good correlation with an analysis.
Park, Kyung Soon; Diwanji, Sanket R; Kim, Hyung Keun; Song, Eun Kyoo; Yoon, Taek Rim
2009-08-01
Iliopsoas bursitis has been increasingly recognized as a complication of total hip arthroplasty and is usually associated with polyethylene wear. Here, the authors report a case of hemorrhagic iliopsoas bursitis complicating an otherwise well-functioning ceramic-on-ceramic arthroplasty performed by minimal invasive modified 2-incision technique. The bursitis in turn resulted in femoral nerve palsy and femoral vein compression. In this report, there was no evidence to support that the bursitis was due to an inflammatory response to ceramic wear particles or any other wear particles originating from the total hip arthroplasty.
Early patient-reported outcomes versus objective function after total hip and knee arthroplasty
DEFF Research Database (Denmark)
Luna, I E; Kehlet, H; Peterson, B
2017-01-01
AIMS: The purpose of this study was to assess early physical function after total hip or knee arthroplasty (THA/TKA), and the correlation between patient-reported outcome measures, physical performance and actual physical activity (measured by actigraphy). PATIENTS AND METHODS: A total of 80...... patients aged 55 to 80 years undergoing THA or TKA for osteoarthritis were included in this prospective cohort study. The main outcome measure was change in patient reported hip or knee injury and osteoarthritis outcome score (HOOS/KOOS) from pre-operatively until post-operative day 13 (THA) or 20 (TKA...
Chronological changes in functional cup position at 10 years after total hip arthroplasty.
Okanoue, Yusuke; Ikeuchi, Masahiko; Takaya, Shogo; Izumi, Masashi; Aso, Koji; Kawakami, Teruhiko
2017-09-19
This study aims to clarify the chronological changes in functional cup position at a minimum follow-up of 10 years after total hip arthroplasty (THA), and to identify the risk factors influencing a significant difference in functional cup position during the postoperative follow-up period. We evaluated the chronological changes in functional cup position at a minimum follow-up of 10 years after THA in 58 patients with unilateral hip osteoarthritis. Radiographic cup position was measured on anteroposterior pelvic radiographs with the patient in the supine position, whereas functional cup position was recorded in the standing position. Radiographs were obtained before, 3 weeks after, and every 1 year after surgery. Functional cup anteversion (F-Ant) increased over time, and was found to have significantly increased at final follow-up compared to that at 3 weeks after surgery (p10° anteriorly. Preoperative posterior pelvic tilt in the standing position and vertebral fractures after THA were significant predictors of increasing functional cup anteversion. Although chronological changes in functional cup position do occur after THA, their magnitude is relatively low. However, posterior impingement is likely to occur, which may cause edge loading, wear of the polyethylene liner, and anterior dislocation of the hip. We believe that, for the combined anteversion technique, the safe zone should probably be 5°-10° narrower in patients predicted to show considerable changes in functional cup position compared with standard cases.
Total and Direct Correlation Function Integrals from Molecular Simulation of Binary Systems
DEFF Research Database (Denmark)
Wedberg, Nils Hejle Rasmus Ingemar; O’Connell, John P.; Peters, Günther H.J.
2011-01-01
The possibility for obtaining derivative properties for mixtures from integrals of spatial total and direct correlation functions obtained from molecular dynamics simulations is explored. Theoretically well-supported methods are examined to extend simulation radial distribution functions to long...... are consistent with an excess Helmholtz energy model fitted to available simulations. In addition, simulations of water/methanol and water/t-butanol mixtures have been carried out. The method yields results for partial molar volumes, activity coefficient derivatives, and individual correlation function integrals...... in reasonable agreement with smoothed experimental data. The proposed method for obtaining correlation function integrals is shown to perform at least as well as or better than two previously published approaches....
Allergy and respiratory health effects of dampness and dampness-related agents in schools and homes
DEFF Research Database (Denmark)
Holst, G; Høst, A; Doekes, G
2016-01-01
was identified based on technical inspection and bedroom dampness on parents' self-report. Classroom and bedroom dust was analysed for seven microbial components. Skin-prick-testing determined atopic sensitisation. Lung function was expressed as z-scores for forced expiratory volume in one second (zFEV1...... ), forced vital capacity (zFVC) and the ratio zFEV1 /zFVC using GLI-2012-prediction-equations. The parents reported children's allergies, airway symptoms and doctor-diagnosed asthma. High classroom dampness, but not bedroom dampness, was negatively associated with zFEV1 (β-coef. -0.71; 95%CI -1.17 - -0...... (ETS) decreased zFEV1 (β-coef. -0.22; 95%CI -0.42- -0.02) and zFEV1 /zFVC-ratio (β-coef. -0.26; 95%CI -0.44 - -0.07) and increased upper airway symptoms (OR1.66; 95%CI 1.03-2.66). In conclusion, dampness in classrooms may have adverse respiratory health effects in pupils, but microbial agents...
Collisional damping rates for plasma waves
Energy Technology Data Exchange (ETDEWEB)
Tigik, S. F., E-mail: sabrina.tigik@ufrgs.br; Ziebell, L. F., E-mail: luiz.ziebell@ufrgs.br [Instituto de Física, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Rio Grande do Sul (Brazil); Yoon, P. H., E-mail: yoonp@umd.edu [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)
2016-06-15
The distinction between the plasma dynamics dominated by collisional transport versus collective processes has never been rigorously addressed until recently. A recent paper [P. H. Yoon et al., Phys. Rev. E 93, 033203 (2016)] formulates for the first time, a unified kinetic theory in which collective processes and collisional dynamics are systematically incorporated from first principles. One of the outcomes of such a formalism is the rigorous derivation of collisional damping rates for Langmuir and ion-acoustic waves, which can be contrasted to the heuristic customary approach. However, the results are given only in formal mathematical expressions. The present brief communication numerically evaluates the rigorous collisional damping rates by considering the case of plasma particles with Maxwellian velocity distribution function so as to assess the consequence of the rigorous formalism in a quantitative manner. Comparison with the heuristic (“Spitzer”) formula shows that the accurate damping rates are much lower in magnitude than the conventional expression, which implies that the traditional approach over-estimates the importance of attenuation of plasma waves by collisional relaxation process. Such a finding may have a wide applicability ranging from laboratory to space and astrophysical plasmas.
Jones, Kevin B; Griffin, Anthony M; Chandrasekar, Coonoor R; Biau, David; Babinet, Antoine; Deheshi, Benjamin; Bell, Robert S; Grimer, Robert J; Wunder, Jay S; Ferguson, Peter C
2011-11-01
Functional outcomes following oncologic total femoral endoprosthetic reconstruction (TFR) are lacking. We compared patient-oriented functional results of TFRs to proximal femur and distal femur reconstructions (PFR and DFR). We also compared function and complications with regard to knee and hip componentry. Fifty-four TFR patients were identified from three institutional prospective databases. Forty-one had fixed- and 13 had rotating-hinge knees, 37 hemiarthroplasty and 17 total hip arthroplasty componentry. Toronto Extremity Salvage Scores (TESS) for n = 27 were compared between groups and to cohorts of PFR (n = 31) and DFR (n = 85) patients using the Mann-Whitney U-test. Follow-up averaged 4 years. Mechanical complications included five hip dislocations and one femoral malrotation. Four dislocations were in fixed-hinge implants, all in those lacking abductor reattachment. TESS averaged 69.3 ± 17.8, statistically decreased from DFR (P = 0.002) and PFR patients (P = 0.036). No significant differences were detected between patients in the fixed-hinge (n = 18) and rotating-hinge (n = 9) groups (P = 0.944), or total hip (n = 8) and hemiarthroplasty (n = 19) groups (P = 0.633). TFR is reserved for extreme cases of limb salvage, portending a poor prognosis overall. Function reflects additive impairments from PFR and DFR. TFR outcomes differ little with rotating- or fixed-hinge, total hip or hemiarthroplasty implants. Copyright © 2011 Wiley Periodicals, Inc.
Olfactory function and quality of life after olfaction rehabilitation in total laryngectomees.
Santos, Christiane Gouvêa Dos; Bergmann, Anke; Coça, Kaliani Lima; Garcia, Angela Albuquerque; Valente, Tânia Cristina de Oliveira
2016-01-01
To evaluate the effects of olfaction rehabilitation in the olfactory function and quality of life of total laryngectomized patients. Pre-post intervention clinical study conducted with total laryngectomees submitted to olfaction rehabilitation by means of the Nasal Airflow-Inducing Maneuver (NAIM) using the University of Pennsylvania Smell Identification Test (UPSIT), Olfactory Acuity Questionnaires, a Monitoring Questionnaire, and the University of Washington Quality of Life Questionnaire (UW-QOL). Participants were 45 total laryngectomees. Before olfaction rehabilitation, 48.9% of the participants had their olfactic abilities classified as anosmia, 46.8% as microsmia, and 4.4% were considered within the normal range. After olfaction rehabilitation, 4.4% of the participants were classified as anosmia and 31.1% were within the normal range. In the Smell Identification Test, the mean score after rehabilitation showed statistically significant improvement. Reponses to the Olfactory Acuity Questionnaires after rehabilitation showed improvement in the frequency of perception regarding smell, taste, and the ability to smell perfume, food, leaking gas, and smoke, after learning the maneuver. Although the scores in the Quality of Life Questionnaire already indicated good quality of life before the surgery, post-intervention values were statistically significant. Olfaction rehabilitation improves olfactory function and has a positive impact on the activities of daily living and quality of life of total laryngectomized patients.
International Nuclear Information System (INIS)
Sanders, J.E.; Buckner, C.D.; Leonard, J.M.; Sullivan, K.M.; Witherspoon, R.P.; Deeg, H.J.; Storb, R.; Thomas, E.D.
1983-01-01
One hundred thirty-seven patients had gonadal function evaluated 1-11 years after marrow transplantation. All 15 women less than age 26 and three of nine older than age 26 who were treated with 200 mg/kg cyclophosphamide recovered normal gonadotropin levels and menstruation. Five have had five pregnancies resulting in three live births, one spontaneous abortion, and one elective abortion. Three of 38 women who were prepared with 120 mg/kg cyclophosphamide and 920-1200 rad total-body irradiation had normal gonadotropin levels and menstruation. Two had pregnancies resulting in one spontaneous and one elective abortion. Of 31 men prepared with 200 mg/kg cyclophosphamide, 30 had normal luteinizing hormone levels, 20 had normal follicle-stimulating hormone levels, and 10 of 15 had spermatogenesis. Four have fathered five normal children. Thirty-six of 41 men prepared with 120 mg/kg cyclophosphamide and 920-1750 rad total-body irradiation had normal luteinizing hormone levels, ten had normal follicle-stimulating hormone levels, and 2 of 32 studied had spermatogenesis. One has fathered two normal children. It was concluded that cyclophosphamide does not prevent return of normal gonadal function in younger women and in most men. Total-body irradiation prevents return of normal gonadal function in the majority of patients
Evaluation of the hepatobiliary function with 99mTc-EHIDA imaging during total parenteral nutrition
International Nuclear Information System (INIS)
Zhou Qian; Jiang Zhouming; Yang Meifang
1988-01-01
14 surgical patients with non-hepatobiliary diseases were studied with 99m Tc-EHIDA imaging to evaluate the effect of total parenteral nutrition (TPN) on the hepatobiliary function. Duration of TPN ranged from 6-56 days, 10 of the 14 patients Beijing within 10 days. The results showed that: (1) 11 of 14 patients had abnormal scintigraphic features. The most prominet findings were delayed liver excretion and prolonged blood clearance time. This fact suggests that not only the rate of excretion of the bile from the liver is decreased but the uptake ability of the hepatorcyte is also impaired. (2) The effect of TPN on liver function is reversible. It was concluded that in order to prevent irreversible damage of hepatobiliary function caused by TPN, the duration of TPN should not be too long and oral intake of nutrients should be resumed as soon as possible
Personality, function and satisfaction in patients undergoing total hip or knee replacement.
Ramaesh, Rishikesan; Jenkins, Paul; Lane, Judith V; Knight, Sara; Macdonald, Deborah; Howie, Colin
2014-03-01
The aim of this study was to investigate the relationships between personality and joint-specific function, general physical and general mental health in patients undergoing total hip (THA) and knee arthroplasty (TKA). One hundred and eighty-four patients undergoing THA and 205 undergoing TKA were assessed using the Eysneck Personality Questionnaire, brief version (EPQ-BV). General physical and mental health was measured using the Short-Form 12 (SF-12) questionnaire and the EuroQol (EQ-5D). Joint-specific function was measured using the Oxford hip or knee score. The "unstable introvert" personality type was associated with poorer pre-operative function and health in patients with hip arthrosis. In patients with knee arthrosis, there was poorer general health in those with "stable extrovert" and "unstable introvert" types. Personality was not an independent predictor of outcome following TKA or THA. The main predictor was pre-operative function and health. Comorbidity was an important covariate of both pre-operative and postoperative function. Personality may play a role in the interaction of these disease processes with function and health perception. It may also affect the response and interpretation of psychometric and patient-reported outcome measures. It may be important to characterise and identify these traits in potential arthroplasty patients as it may help deliver targeted education and management to improve outcomes in certain groups.
Energy Technology Data Exchange (ETDEWEB)
Bulos, Fatin [SLAC National Accelerator Lab., Menlo Park, CA (United States); Tomlin, Bill T. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Weaver, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2014-03-04
The principle of the design of these magnets was discussed in CN-72. Fig. 1 shows what the total system looks like. Such a system was completed last January and since then we have been evaluating its performance.
Breukink, S O; van der Zaag-Loonen, H J; Bouma, E M C; Pierie, J P E N; Hoff, C; Wiggers, T; Meijerink, W J H J
2007-02-01
This study was designed to investigate how the quality of life of patients with rectal cancer changes with time after laparoscopic total mesorectal excision. Patients completed the Medical Outcomes Study Short Form 36 and the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire and a colorectal-specific European Organisation for Research and Treatment of Cancer quality of life questionnaire before laparoscopic total mesorectal excision, on discharge from the hospital and at 3, 6, and 12 months postoperatively. Patients were treated by laparoscopic low anterior resection or laparoscopic abdominoperineal resection. Fifty-one patients (mean age, 64 years; 29 males (57 percent)) participated in this study, of whom 38 (75 percent) underwent laparoscopic low anterior resection and 13 (25 percent) laparoscopic abdominoperineal resection. Compared with preoperative scores on the Medical Outcomes Study Short Form 36, patients reported a deterioration in physical functioning (74 vs. 80; P = 0.009), and improved mental functioning (76 vs. 70; P = 0.007) at three months. Improvement in emotional well-being was reported both on the Medical Outcomes Study Short Form 36 (78 vs. 53; P = 0.006) and the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (84 vs. 69; P < 0.001). At one year, improvements in global quality of life (82 vs. 68; P = 0.001) and symptoms, such as fatigue (18 vs. 32; P < 0.001), pain (5 vs. 12; P = 0.009), and appetite loss (3 vs. 13; P = 0.01), were reported. Sexual functioning was worse from three months onward until one year after surgery (47 vs. 66; P = 0.004). Patients who underwent low anterior resection experienced less sexual dysfunction than patients after abdominoperineal resection (21 vs. 56; P = 0.004). One year after laparoscopic total mesorectal excision for rectal cancer, patients reported improvement in some important quality of life outcomes, including global quality
Functional exercise after total hip replacement (FEATHER a randomised control trial
Directory of Open Access Journals (Sweden)
Monaghan Brenda
2012-11-01
Full Text Available Abstract Background Prolonged physical impairments in range of movement, postural stability and walking speed are commonly reported following total hip replacement (THR. It is unclear from the current body of evidence what kind of exercises should be performed to maximize patient function and quality of life. Methods/design This will be a single blind multi centre randomized control trial with two arms. Seventy subjects post primary total hip arthroplasty will be randomized into either an experimental group (n=35, or to a control group (n=35. The experimental group will attend a functional exercise class twice weekly for a six week period from week 12 to week 18 post surgery. The functional exercise group will follow a circuit based functional exercise class supervised by a chartered Physiotherapist. The control group will receive usual care. The principal investigator (BM will perform blinded outcome assessments on all patients using validated measures for pain, stiffness, and function using the Western Ontario and Mc Master Universities Osteoarthritis index (WOMAC. This is the primary outcome measurement tool. Secondary outcome measurements include Quality of life (SF-36, 6 min walk test, Visual Analogue Scale, and the Berg Balance score. The WOMAC score will be collated on day five post surgery and repeated at week twelve and week eighteen. All other measurements will be taken at week 12 and repeated at week eighteen. In addition a blinded radiologist will measure gluteus medius cross sectional area using real time ultrasound for all subjects at week 12 and at week 18 to determine if the functional exercise programme has any effect on muscle size. Discussion This randomised controlled trial will add to the body of evidence on the relationship between muscle size, functional ability, balance, quality of life and time post surgery in patients following total hip arthroplasty. The CONSORT guidelines will be followed to throughout. Ethical
An ecological function and services approach to total maximum daily load (TMDL) prioritization.
Hall, Robert K; Guiliano, David; Swanson, Sherman; Philbin, Michael J; Lin, John; Aron, Joan L; Schafer, Robin J; Heggem, Daniel T
2014-04-01
Prioritizing total maximum daily load (TMDL) development starts by considering the scope and severity of water pollution and risks to public health and aquatic life. Methodology using quantitative assessments of in-stream water quality is appropriate and effective for point source (PS) dominated discharge, but less so in watersheds with mostly nonpoint source (NPS) related impairments. For NPSs, prioritization in TMDL development and implementation of associated best management practices should focus on restoration of ecosystem physical functions, including how restoration effectiveness depends on design, maintenance and placement within the watershed. To refine the approach to TMDL development, regulators and stakeholders must first ask if the watershed, or ecosystem, is at risk of losing riparian or other ecologically based physical attributes and processes. If so, the next step is an assessment of the spatial arrangement of functionality with a focus on the at-risk areas that could be lost, or could, with some help, regain functions. Evaluating stream and wetland riparian function has advantages over the traditional means of water quality and biological assessments for NPS TMDL development. Understanding how an ecosystem functions enables stakeholders and regulators to determine the severity of problem(s), identify source(s) of impairment, and predict and avoid a decline in water quality. The Upper Reese River, Nevada, provides an example of water quality impairment caused by NPS pollution. In this river basin, stream and wetland riparian proper functioning condition (PFC) protocol, water quality data, and remote sensing imagery were used to identify sediment sources, transport, distribution, and its impact on water quality and aquatic resources. This study found that assessments of ecological function could be used to generate leading (early) indicators of water quality degradation for targeting pollution control measures, while traditional in-stream water
Calculations of emittance and damping time effects in the SLC damping rings
International Nuclear Information System (INIS)
Limberg, T.; Moshammer, H.; Raubenheimer, T.; Spencer, J.; Siemann, R.
1992-03-01
In a recent NDR machine experiment the transverse emittance was studied as a function of store time and tune. To explain the observed transverse emittance damping time constants, the magnetic measurement data of the longitudinal field of the bending magnets had to be taken into account. The variation of the transverse emittances with tune due to misalignments and the associated anomalous dispersion is studied as well as the effect of synchrobetatron coupling due to dispersion in the RF cavities
Robust Rudder Roll Damping Control
DEFF Research Database (Denmark)
Yang, C.
The results of a systematic research to solve a specific ship motion control problem, simultaneous roll damping and course keeping using the rudder are presented in this thesis. The fundamental knowledge a priori is that rudder roll damping is highly sensitive to the model uncertainty, therefore H-infinity...... theory is used to deal with the problem. The necessary mathematical tools and the H-Infinity theory as the basis of controller design are presented in Chapter 2 and 3. The mu synthesis and the D-K iteration are introduced in Chapter 3. The ship dynamics and modeling technology are discussed in Chapter 4...
Damping ring designs and issues
International Nuclear Information System (INIS)
Wolski, Andrzej; Decking, Winfried
2003-01-01
The luminosity performance of a future linear collider (LC) will depend critically on the performance of the damping rings. The design luminosities of the current LC proposals require rings with very short damping times, large acceptance, low equilibrium emittance and high beam intensity. We discuss the design strategies for lattices achieving the goals of dynamical stability, examine the challenges for alignment and coupling correction, and consider a variety of collective effects that threaten to limit beam quality. We put the design goals in context by referring to the experience of operating facilities, and outline the further research and development that is needed
Psychological factors as risk factors for poor hip function after total hip arthroplasty
Directory of Open Access Journals (Sweden)
Benditz A
2017-02-01
Full Text Available Achim Benditz,1 Petra Jansen,2 Jan Schaible,1 Christina Roll,1 Joachim Grifka,1 Jürgen Götz1 1Department of Orthopedics, University Medical Center Regensburg, Asklepios Klinikum Bad Abbach, Bad Abbach, 2Department of Sport Science, University of Regensburg, Regensburg, Germany Abstract: Recovery after total hip arthroplasty (THA is influenced by several psychological aspects, such as depression, anxiety, resilience, and personality traits. We hypothesized that preoperative depression impedes early functional outcome after THA (primary outcome measure. Additional objectives were perioperative changes in the psychological status and their influence on perioperative outcome. This observational study analyzed depression, anxiety, resilience, and personality traits in 50 patients after primary unilateral THA. Hip functionality was measured by means of the Harris Hip Score. Depression, state anxiety, and resilience were evaluated preoperatively as well as 1 and 5 weeks postoperatively. Trait anxiety and personality traits were measured once preoperatively. Patients with low depression and anxiety levels had significantly better outcomes with respect to early hip functionality. Resilience and personality traits did not relate to hip functionality. Depression and state anxiety levels significantly decreased within the 5-week stay in the acute and rehabilitation clinic, whereas resilience remained at the same level. Our study suggests that low depression and anxiety levels are positively related to early functionality after THA. Therefore, perioperative measurements of these factors seem to be useful to provide the best support for patients with risk factors. Keywords: total hip arthroplasty, psychological factors, depression, state anxiety, trait anxiety, resilience, personality traits
The power of cross-functional teams in driving total quality
Mcclung, Tim M.; Mcmaster, Tom J.
1992-01-01
Garrett Canada, a Division of Allied-Signal Aerospace Canada, has been a member of the Canadian aerospace industry for 40 years. Although Garrett Canada has always been a profitable division with a solid market share, the changing and turbulent business environment and globalization of the aerospace industry has created new demands and challenges. The marketplace is demanding faster introduction of new products, as well as shorter leadtimes for repairs and spares. It was recognized that reducing cycle times for new products and for ongoing production would not only satisfy our customers, it would also enhance our business performance through reduced inventories, lower past due, and more responsiveness to change. It was evident that drastic function changes were required if we were to maintain our position as a premier aerospace supplier. The challenge was to convert a stable, somewhat slow-paced work environment with strong functional boundaries into a boundaryless world class team functioning in a total quality environment and focused on customer satisfaction. Complete and uncompromised customer satisfaction has become our driving force, with Total Quality being our engine to continuously improve our processes and increase our speed. The way in which this transition has been brought about is the subject of this presentation.
Hintermüller, Michael; Holler, Martin; Papafitsoros, Kostas
2018-06-01
In this work, we introduce a function space setting for a wide class of structural/weighted total variation (TV) regularization methods motivated by their applications in inverse problems. In particular, we consider a regularizer that is the appropriate lower semi-continuous envelope (relaxation) of a suitable TV type functional initially defined for sufficiently smooth functions. We study examples where this relaxation can be expressed explicitly, and we also provide refinements for weighted TV for a wide range of weights. Since an integral characterization of the relaxation in function space is, in general, not always available, we show that, for a rather general linear inverse problems setting, instead of the classical Tikhonov regularization problem, one can equivalently solve a saddle-point problem where no a priori knowledge of an explicit formulation of the structural TV functional is needed. In particular, motivated by concrete applications, we deduce corresponding results for linear inverse problems with norm and Poisson log-likelihood data discrepancy terms. Finally, we provide proof-of-concept numerical examples where we solve the saddle-point problem for weighted TV denoising as well as for MR guided PET image reconstruction.
The Microstructural Basis of Damping in High Damping Alloys
1989-09-01
This transformation is diffusionless and is characterized by the cooperative movement of atoms in a given section of crystal. Removal of the stress...martensites. The cooperative movement of atoms causes large internal friction and high damping. The temperature range in which this transformation can
Right ventricular function late after total repair of tetralogy of Fallot
Energy Technology Data Exchange (ETDEWEB)
Straten, Alexander van; Roos, Albert de [Leiden University Medical Center, Department of Radiology, Leiden (Netherlands); Vliegen, Hubert W. [Leiden University Medical Center, Department of Cardiology, Leiden (Netherlands); Hazekamp, Mark G. [Leiden University Medical Center, Department of Cardiothoracic Surgery, Leiden (Netherlands)
2005-04-01
Over the past decades, life expectancy in patients with congenital heart disease has increased dramatically. However, serious complications may develop late after total repair in infancy. These complications are usually the result of longstanding pulmonary regurgitation, which leads to dilatation of the right ventricle and an increased risk for severe arrhythmias. Therefore lifelong follow-up in these patients is required. Cardiac magnetic resonance imaging is the current imaging tool of choice because it offers superior imaging quality and enables accurate quantification of functional parameters such as flow volumes and systolic and diastolic performance. (orig.)
Right ventricular function late after total repair of tetralogy of Fallot
International Nuclear Information System (INIS)
Straten, Alexander van; Roos, Albert de; Vliegen, Hubert W.; Hazekamp, Mark G.
2005-01-01
Over the past decades, life expectancy in patients with congenital heart disease has increased dramatically. However, serious complications may develop late after total repair in infancy. These complications are usually the result of longstanding pulmonary regurgitation, which leads to dilatation of the right ventricle and an increased risk for severe arrhythmias. Therefore lifelong follow-up in these patients is required. Cardiac magnetic resonance imaging is the current imaging tool of choice because it offers superior imaging quality and enables accurate quantification of functional parameters such as flow volumes and systolic and diastolic performance. (orig.)
Time-dependent density functional theory description of total photoabsorption cross sections
Tenorio, Bruno Nunes Cabral; Nascimento, Marco Antonio Chaer; Rocha, Alexandre Braga
2018-02-01
The time-dependent version of the density functional theory (TDDFT) has been used to calculate the total photoabsorption cross section of a number of molecules, namely, benzene, pyridine, furan, pyrrole, thiophene, phenol, naphthalene, and anthracene. The discrete electronic pseudo-spectra, obtained in a L2 basis set calculation were used in an analytic continuation procedure to obtain the photoabsorption cross sections. The ammonia molecule was chosen as a model system to compare the results obtained with TDDFT to those obtained with the linear response coupled cluster approach in order to make a link with our previous work and establish benchmarks.
Statistical mechanics of quantum one-dimensional damped harmonic oscillator
International Nuclear Information System (INIS)
Borges, E.N.M.; Borges, O.N.; Ribeiro, L.A.A.
1985-01-01
We calculate the thermal correlation functions of the one-dimensional damped harmonic oscillator in contact with a reservoir, in an exact form by applying Green's function method. In this way the thermal fluctuations are incorporated in the Caldirola-Kanai Hamiltonian
Knee awareness and functionality after simultaneous bilateral vs unilateral total knee arthroplasty
DEFF Research Database (Denmark)
Latifi, Roshan; Thomsen, Morten Grove; Kallemose, Thomas
2016-01-01
AIM: To investigate knee awareness and functional outcomes in patients treated with simultaneous bilateral vs unilateral total knee arthroplasty (TKA). METHODS: Through a database search, we identified 210 patients who had undergone unilateral TKA (UTKA) and 65 patients who had undergone......-surgical treatments were failed, thus preoperatively the patients had poor functionality. All patients were asked to complete Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) questionnaires. The patients were matched according to age, gender, year of surgery, Kellgren-Lawrence score and pre- and postoperative...... overall knee alignment. The FJS and OKS questionnaire results of the two groups were then compared. RESULTS: A mixed-effects model was used to analyze differences between SBTKA and UTKA. OKS: The mean difference in the OKS between the patients who had undergone SBTKA and those who had undergone UTKA was 1...
Predictors of pain and physical function at 3 and 12 months after total hip arthroplasty
DEFF Research Database (Denmark)
Plews, Sarah; Løvlund Nielsen, Randi; Overgaard, Søren
Background: Few studies have combined preoperative patient-reported and objective outcome measures to predict outcomes after total hip arthroplasty (THA). Purpose / Aim of Study: to identify predictors of outcome 3 and 12 months after THA Materials and Methods: A cohort of 107 consecutive patients...... with primary hip osteoarthritis responded to Hip dysfunction and Osteoarthritis Outcome Score (HOOS) questionnaires prior to and 3 and 12 months after THA. Preoperative pain intensity; joint space width (JSW), age, gender, and body mass index (BMI) were used to predict changes in pain and physical function....... Conclusions: Preoperative pain predicted changes in pain and physical function up to one year after THA. Such knowledge should be taken into consideration, when assessing OA patients prior to surgery. This study provides useful insight for clinicians, regarding the overall improvement patients can expect...
Yang, Yang; Yu, Haibo; York, Darrin; Cui, Qiang; Elstner, Marcus
2007-10-25
The standard self-consistent-charge density-functional-tight-binding (SCC-DFTB) method (Phys. Rev. B 1998, 58, 7260) is derived by a second-order expansion of the density functional theory total energy expression, followed by an approximation of the charge density fluctuations by charge monopoles and an effective damped Coulomb interaction between the atomic net charges. The central assumptions behind this effective charge-charge interaction are the inverse relation of atomic size and chemical hardness and the use of a fixed chemical hardness parameter independent of the atomic charge state. While these approximations seem to be unproblematic for many covalently bound systems, they are quantitatively insufficient for hydrogen-bonding interactions and (anionic) molecules with localized net charges. Here, we present an extension of the SCC-DFTB method to incorporate third-order terms in the charge density fluctuations, leading to chemical hardness parameters that are dependent on the atomic charge state and a modification of the Coulomb scaling to improve the electrostatic treatment within the second-order terms. These modifications lead to a significant improvement in the description of hydrogen-bonding interactions and proton affinities of biologically relevant molecules.
Preoperative physiotherapy and short-term functional outcomes of primary total knee arthroplasty.
Mat Eil Ismail, Mohd Shukry; Sharifudin, Mohd Ariff; Shokri, Amran Ahmed; Ab Rahman, Shaifuzain
2016-03-01
Physiotherapy is an important part of rehabilitation following arthroplasty, but the impact of preoperative physiotherapy on functional outcomes is still being studied. This randomised controlled trial evaluated the effect of preoperative physiotherapy on the short-term functional outcomes of primary total knee arthroplasty (TKA). 50 patients with primary knee osteoarthritis who underwent unilateral primary TKA were randomised into two groups: the physiotherapy group (n = 24), whose patients performed physical exercises for six weeks immediately prior to surgery, and the nonphysiotherapy group (n = 26). All patients went through a similar physiotherapy regime in the postoperative rehabilitation period. Functional outcome assessment using the algofunctional Knee Injury and Osteoarthritis Outcome Score (KOOS) scale and range of motion (ROM) evaluation was performed preoperatively, and postoperatively at six weeks and three months. Both groups showed a significant difference in all algofunctional KOOS subscales (p 0.05). Significant differences were observed in the time-versus-treatment analysis between groups for the symptoms (p = 0.003) and activities of daily living (p = 0.025) subscales. No significant difference in ROM was found when comparing preoperative measurements and those at three months following surgery, as well as in time-versus-treatment analysis (p = 0.928). Six-week preoperative physiotherapy showed no significant impact on short-term functional outcomes (KOOS subscales) and ROM of the knee following primary TKA. Copyright: © Singapore Medical Association.
Male sexual function and lower urinary tract symptoms after laparoscopic total mesorectal excision.
Breukink, S O; van Driel, M F; Pierie, J P E N; Dobbins, C; Wiggers, T; Meijerink, W J H J
2008-12-01
The aim of this study was to investigate sexual function and the presence of lower urinary tract symptoms (LUTS) in male patients with rectal cancer following short-term radiotherapy and laparoscopic total mesorectal excision (LTME) by physical and psychological measurements. Sexual function and LUTS were assessed by the use of questionnaires [International Index of Erectile Function (IIEF), International Prostate Symptom Score]. Sexual function was further assessed by the use of pharmaco duplex ultrasonography of the cavernous arterial blood flow and nocturnal penile tumescence and rigidity monitoring (NPTR). All investigations were performed prior to the start of preoperative radiotherapy and 15 months after surgery. Nine patients (mean age 60 years) participated. Erectile function was maintained in 71% and ejaculation function in 89%. Compared with pre-operative scores on the IIEF, a significant deterioration in intercourse satisfaction was seen following radiotherapy and LTME (7.9 vs 10.3, p = 0.042), but overall satisfaction remained unchanged (8.0 vs 7.0, p = 0.246). NPTR parameters (duration of erectile episodes, duration of tip rigidity > or =60%) decreased following radiotherapy and LTME. Patients reported a deterioration in micturition frequency (2.0 vs 1.0, p = 0.034) and quality of life due to urinary symptoms (8.0 vs 1.8, p = 0.018). Based on these first preliminary findings, data suggest that 15 months after short-term radiotherapy and LTME in men with rectal cancer, objectively assessed sexual dysfunction was considerable, but overall sexual satisfaction had not changed.
Directory of Open Access Journals (Sweden)
Zheng Ling
2011-01-01
Full Text Available Damping treatments have been extensively used as a powerful means to damp out structural resonant vibrations. Usually, damping materials are fully covered on the surface of plates. The drawbacks of this conventional treatment are also obvious due to an added mass and excess material consumption. Therefore, it is not always economical and effective from an optimization design view. In this paper, a topology optimization approach is presented to maximize the modal damping ratio of the plate with constrained layer damping treatment. The governing equation of motion of the plate is derived on the basis of energy approach. A finite element model to describe dynamic performances of the plate is developed and used along with an optimization algorithm in order to determine the optimal topologies of constrained layer damping layout on the plate. The damping of visco-elastic layer is modeled by the complex modulus formula. Considering the vibration and energy dissipation mode of the plate with constrained layer damping treatment, damping material density and volume factor are considered as design variable and constraint respectively. Meantime, the modal damping ratio of the plate is assigned as the objective function in the topology optimization approach. The sensitivity of modal damping ratio to design variable is further derived and Method of Moving Asymptote (MMA is adopted to search the optimized topologies of constrained layer damping layout on the plate. Numerical examples are used to demonstrate the effectiveness of the proposed topology optimization approach. The results show that vibration energy dissipation of the plates can be enhanced by the optimal constrained layer damping layout. This optimal technology can be further extended to vibration attenuation of sandwich cylindrical shells which constitute the major building block of many critical structures such as cabins of aircrafts, hulls of submarines and bodies of rockets and missiles as an
Dampness in buildings and health
DEFF Research Database (Denmark)
Bornehag, Carl-Gustaf; Blomquist, G.; Gyntelberg, F.
2001-01-01
Several epidemiological investigations concerning indoor environments have indicated that "dampness" in buildings is associated to health effects such as respiratory symptoms, asthma and allergy The aim of the present interdisciplinary review is to evaluate this association as shown in the epidem...
Nonlocal quasilinear damped differential inclusions
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Mouffak Benchohra
2002-01-01
Full Text Available In this paper we investigate the existence of mild solutions to second order initial value problems for a class of damped differential inclusions with nonlocal conditions. By using suitable fixed point theorems, we study the case when the multivalued map has convex and nonconvex values.
Marhauser, Frank
2017-06-01
Research and development for superconducting radio-frequency cavities has made enormous progress over the last decades from the understanding of theoretical limitations to the industrial mass fabrication of cavities for large-scale particle accelerators. Key technologies remain hot topics due to continuously growing demands on cavity performance, particularly when in pursuit of high quality beams at higher beam currents or higher luminosities than currently achievable. This relates to higher order mode (HOM) damping requirements. Meeting the desired beam properties implies avoiding coupled multi-bunch or beam break-up instabilities depending on the machine and beam parameters that will set the acceptable cavity impedance thresholds. The use of cavity HOM-dampers is crucial to absorb the wakefields, comprised by all beam-induced cavity Eigenmodes, to beam-dynamically safe levels and to reduce the heat load at cryogenic temperature. Cavity damping concepts may vary, but are principally based on coaxial and waveguide couplers as well as beam line absorbers or any combination. Next generation energy recovery linacs and circular colliders call for cavities with strong HOM-damping that can exceed the state-of-the-art, while the operating mode efficiency shall not be significantly compromised concurrently. This imposes major challenges given the rather limited damping concepts. A detailed survey of established cavities is provided scrutinizing the achieved damping performance, shortcomings, and potential improvements. The scaling of the highest passband mode impedances is numerically evaluated in dependence on the number of cells for a single-cell up to a nine-cell cavity, which reveals the increased probability of trapped modes. This is followed by simulations for single-cell and five-cell cavities, which incorporate multiple damping schemes to assess the most efficient concepts. The usage and viability of on-cell dampers is elucidated for the single-cell cavity since it
Tranexamic acid increases early perioperative functional outcomes after total knee arthroplasty
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Matthew J. Grosso, MD
2018-03-01
Full Text Available Background: The purpose of this study was to investigate the influence of tranexamic acid (TXA on functional outcomes in the immediate postoperative period after total knee arthroplasty (TKA. We hypothesized that the known benefits of TXA would confer measurable clinical improvements in physical therapy (PT performance, decrease pain, and decrease hospital length of stay (LOS. Methods: We retrospectively analyzed 560 TKA patients, including 280 consecutive patients whose surgery was performed before the initiation of a standardized TXA protocol and the first 280 patients who received TXA after protocol initiation. Outcome measurements included postoperative changes in hemoglobin and hematocrit, LOS, pain scores, destination of discharge, and steps ambulated with PT over 5 sessions. Results: TXA administration resulted in less overall drops in hemoglobin (P < .001 and hematocrit levels (P < .001. Moreover, patients administered TXA ambulated more than their counterparts during every PT session, which was statistically significant during the second (P = .010, third (P = .011, and fourth (P = .024 sessions. On average, the TXA cohort ambulated 20% more per PT session than patients who did not receive TXA (P < .001. TXA administration did not influence pain levels during PT, hospital LOS, or discharge destination in this investigation. Conclusions: It is well known that TXA reduces postoperative anemia, but this study also demonstrates that it confers early perioperative functional benefits for TKA patients. Potential mechanisms for this benefit include reduced rates of postoperative anemia and reduced rates of hemarthroses. Keywords: Tranexamic acid, Total knee arthroplasty, Blood loss, Physical therapy
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Delin Zhang
2016-01-01
Full Text Available Background: This study aimed to compare the effects of different depths of sedation during total intravenous anesthesia (TIVA with remifentanil and propofol given by target-controlled infusion (TCI on postoperative cognitive function in young and middle-aged patients undergoing gynecological laparoscopic surgery. Materials and Methods: A total of 150 American Society of Anesthesiologists physical Status I/II patients scheduled for gynecological laparoscopic operation were randomly divided into three groups. Anesthesia was maintained with intravenous infusion of TCI propofol and remifentanil, intermittent injected intravenously with rocuronium. The infusion concentration of propofol and remifentanil was adjusted to maintain bispectral index (BIS at 30 24 sores on the day before anesthesia and the day after surgery in all three groups. However, the first group had the significantly higher MMSE scores than the other two groups after surgery (P < 0.05. Compared with that before anesthesia, TMT completion time was shorter on the day after surgery in the first group, while prolonged in the third group (P < 0.05. The first group had the significantly lower TMT completion time than the other two groups (P < 0.05. Conclusion: The depth of sedation, 30 < BIS value ≤ 40, under TIVA with remifentanil and propofol given by TCI had the minimal influence on postoperative cognitive function.
Damped Oscillator with Delta-Kicked Frequency
Manko, O. V.
1996-01-01
Exact solutions of the Schrodinger equation for quantum damped oscillator subject to frequency delta-kick describing squeezed states are obtained. The cases of strong, intermediate, and weak damping are investigated.
Nuclear piping system damping data studies
International Nuclear Information System (INIS)
Ware, A.G.; Arendts, J.G.
1985-01-01
A programm has been conducted at the Idaho National Engineering Laboratory to study structural damping data for nuclear piping systems and to evaluate if changes in allowable damping values for structural seismic analyses are justified. The existing pipe damping data base was examined, from which a conclusion was made that there were several sets of data to support higher allowable values. The parameters which most influence pipe damping were identified and an analytical investigation demonstrated that increased damping would reduce the required number of seismic supports. A series of tests on several laboratory piping systems was used to determine the effect of various parameters such as types of supports, amplitude of vibration, frequency, insulation, and pressure on damping. A multiple regression analysis was used to statistically assess the influence of the various parameters on damping, and an international pipe damping data bank has been formed. (orig.)
Hsu, Wei-Hsiu; Hsu, Wei-Bin; Shen, Wun-Jer; Lin, Zin-Rong; Chang, Shr-Hsin; Hsu, Robert Wen-Wei
2017-10-19
The number of patients receiving total knee arthroplasty (TKA) has been rising every year due to the aging population and the obesity epidemic. Post-operative rehabilitation is important for the outcome of TKA. A series of 34 patients who underwent primary unilateral TKA was retrospectively collected and divided into either exercise group (n = 16) and control group (n = 18). The exercise group underwent a 24-week course of circuit training beginning 3 months after total knee arthroplasty (TKA). The effect of circuit training on TKA patients in terms of motion analysis, muscle strength testing, Knee injury and Osteoarthritis Outcomes Score (KOOS) questionnaire and patient-reported outcome measurement Short-Form Health Survey (SF-36) at the pre-operation, pre-exercise, mid-exercise, and post-exercise. Motion analysis revealed the stride length, step velocity, and excursion of active knee range of motion significantly improved in the exercise group when compared to those in the control group. KOOS questionnaire showed a greater improvement in pain, ADL, and total scores in the exercise group. The SF-36 questionnaire revealed a significant improvement in general health, bodily pain, social function, and physical components score in the exercise group. The post-operative circuit training intervention can facilitate recovery of knee function and decrease the degree of pain in the TKA and might be considered a useful adjunct rehabilitative modality. The ultimate influence of circuit training on TKA needs further a prospective randomized clinical trial study and long-term investigation. NCT02928562.
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Ali Nasser Hussain
2016-09-01
Full Text Available The aim of this study is to present a comprehensive comparison and assessment of the damping function improvement of power system oscillation for the multiple damping controllers using the simultaneously coordinated design based on Power System Stabilizer (PSS and Flexible AC Transmission System (FACTS devices. FACTS devices can help in the enhancing the stability of the power system by adding supplementary damping controller to the control channel of the FACTS input to implement the task of Power Oscillation Damping (FACT POD controller. Simultaneous coordination can be performed in different ways. First, the dual coordinated designs between PSS and FACTS POD controller or between different FACTS POD controllers are arranged in a multiple FACTS devices without PSS. Second, the simultaneous coordination has been extended to triple coordinated design among PSS and different FACTS POD controllers. The parameters of the damping controllers have been tuned in the individual controllers and coordinated designs by using a Chaotic Particle Swarm Optimization (CPSO algorithm that optimized the given eigenvalue-based objective function. The simulation results for a multi-machine power system show that the dual coordinated design provide satisfactory damping performance over the individual control responses. Furthermore, the triple coordinated design has been shown to be more effective in damping oscillations than the dual damping controllers.
Vibration Damping Via Acoustic Treatment Attached To Vehicle Body Panels
Gambino, Carlo
Currently, in the automotive industry, the control of noise and vibration is the subject of much research, oriented towards the creation of innovative solutions to improve the comfort of the vehicle and to reduce its cost and weight. This thesis fits into this particular framework, as it aims to investigate the possibility of integrating the functions of sound absorptioninsulation and vibration damping in a unique component. At present the bituminous viscoelastic treatments, which are bonded to the car body panels, take charge of the vibration damping, while the sound absorption and insulation is obtained by means of the poroacoustic treatments. The solution proposed here consists of employing porous materials to perform both these functions, thus allowing the partial or complete removal of the viscoelastic damping treatments from the car body. This should decrease the weight of the vehicle, reducing fuel consumption and emissions, and it might also benefit production costs.
Study of damping characteristics of fibre reinforced composite aerospace structure
International Nuclear Information System (INIS)
Khan, M.Z.; Saleh, S.; Munir, A.
2006-01-01
Composite materials are used in a variety of high demanding structural applications. Apart from their other preferable properties, they have high-energy dissipation characteristics, which is important aspect when we repeatedly wiggle the system back and forth. It is important to have thorough understanding of material damping behavior; in general materials damping tends to be complex nonlinear function of vibration amplitude, frequency of loading and material formulation. There are number of mathematical models available in literature to obtain hysteresis curves. One approach for identifying damping characteristics used mechanical hysteresis curves. In present work, a phenomenon was observed during testing of fibre reinforced composite beam of an aerospace structure, that for increase load in structure, the path of Force vs. Displacement curve is different than the path of unloading. A plot is generated which indicate the hysteresis loop representing the steady state dynamic behavior of material. The area enclosed by such curves is proportional to energy dissipation per cycle. However, the specific shape of the curve also has important implications for characterizing the specific functional form of the damping. Therefore, it is important to develop methods for accurately accounting for such effects. The current work explores the damping characteristics both theoretically and experimentally. (author)
Functional results of robotic total intersphincteric resection with hand-sewn coloanal anastomosis.
Luca, F; Valvo, M; Guerra-Cogorno, M; Simo, D; Blesa-Sierra, E; Biffi, R; Garberoglio, C
2016-06-01
In recent decades there has been an increasing trend toward sphincter-preserving procedures for the treatment of low rectal cancer. Robotic surgery is considered to be particularly beneficial when operating in the deep pelvis, where laparoscopy presents technical limitations. The aim of this study was to prospectively evaluate the functional outcomes in patients affected by rectal cancer after robotic total intersphincteric resection (ISR) with hand-sewn coloanal anastomosis. From March 2008 to October 2012, 23 consecutive patients affected by distal rectal adenocarcinoma underwent robotic ISR. Operative, clinical, pathological and functional data regarding continence or presence of a low anterior resection syndrome (LARS) were prospectively collected in a database. Twenty-three consecutive patients were included in the study: 8 men and 15 women. The mean age was 60.2 years (range 28-73). Eighteen (78.3%) had neoadjuvant radiochemotherapy. Conversion rate was nil. The mean operative time was 296.01 min and the mean postoperative hospital stay was 7.43 ± 1.73 days. According to Kirwan's incontinence score, good fecal continence was shown in 85.7% of patients (Grade 1 and 2) and none required a colostomy (Grade 4). Concerning LARS score, the results were as follows: 57.1% patients had no LARS; 19% minor LARS and 23.8% major LARS. Robotic total ISR for low rectal cancer is an acceptable alternative to traditional procedures. Extensive discussion with the patient about the risk of poor functional outcomes or LARS syndrome is mandatory when considering an ISR for treatment of low rectal cancer. Copyright © 2016 Elsevier Ltd. All rights reserved.
Iwata, D; Broun, H C; Black, A P; Preston, C A; Anderson, G I
2008-01-01
A retrospective multi-centre study was carried out in order to compare outcomes between cemented and uncemented total hip arthoplasties (THA). A quantitative orthopaedic outcome assessment scoring system was devised in order to relate functional outcome to a numerical score, to allow comparison between treatments and amongst centres. The system combined a radiographic score and a clinical score. Lower scores reflect better outcomes than higher scores. Consecutive cases of THA were included from two specialist practices between July 2002 and December 2005. The study included 46 THA patients (22 uncemented THA followed for 8.3 +/- 4.7M and 24 cemented THA for 26.0 +/- 15.7M) with a mean age of 4.4 +/- 3.3 years at surgery. Multi-variable linear and logistical regression analyses were performed with adjustments for age at surgery, surgeon, follow-up time, uni- versus bilateral disease, gender and body weight. The differences between treatment groups in terms of functional scores or total scores were not significant (p > 0.05). Radiographic scores were different between treatment groups. However, these scores were usually assessed within two months of surgery and proved unreliable predictors of functional outcome (p > 0.05). The findings reflect relatively short-term follow-up, especially for the uncemented group, and do not include clinician-derived measures, such as goniometry and thigh circumference. Longer-term follow-up for the radiographic assessments is essential. A prospective study including the clinician-derived outcomes needs to be performed in order to validate the outcome instrument in its modified form.
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Motasaddi Zarandy M
2007-07-01
Full Text Available Background: Hypothyroidism is a well-documented complication after treatment of laryngeal cancer and is particularly significant among patients undergoing laryngectomy. We investigated the frequency of hypothyroidism in patients treated with total laryngectomy for laryngeal cancer. We also evaluated the effect of neck radiotherapy on thyroid function after total laryngectomy for laryngeal cancer. Methods: In a cross-sectional study, we evaluated 31 patients with laryngeal squamous cell carcinoma (mean age 53.6 years. Among these patients, 14 were treated with surgery only and 17 were treated with surgery plus radiotherapy. Laboratory evaluation included levels of thyroid stimulating hormone (TSH, free T4, free T3, and antithyroid antibodies both preoperatively and postoperatively at the first day, as well as one and six months after surgery. Results: All patients had normal thyroid function before treatment; however, after 6 months, five patients (16.1% were hypothyroid. Of these, three patients (9.6% had subclinical symptoms, including elevated thyroid-stimulating hormone with normal free T4, and two patients (6.5% showed clinical symptoms of hypothyroidism. Radiotherapy and neck dissection were significantly associated with higher incidences of hypothyroidism. Conclusion: Our data suggest that hypothyroidism occurs in a substantial proportion of patients undergoing surgery for laryngeal cancer. The results indicate that thyroid function studies should be routinely performed in the follow-up care of laryngeal cancer patients, especially if radiotherapy and neck dissection were part of the treatment. We suggest that this approach will improve the patient's quality of life and diminish the co-morbidity associated with this kind of surgery.
Fransson, Thomas; Burdakova, Daria; Norman, Patrick
2016-05-21
X-ray absorption spectra of carbon, silicon, germanium, and sulfur compounds have been investigated by means of damped four-component density functional response theory. It is demonstrated that a reliable description of relativistic effects is obtained at both K- and L-edges. Notably, an excellent agreement with experimental results is obtained for L2,3-spectra-with spin-orbit effects well accounted for-also in cases when the experimental intensity ratio deviates from the statistical one of 2 : 1. The theoretical results are consistent with calculations using standard response theory as well as recently reported real-time propagation methods in time-dependent density functional theory, and the virtues of different approaches are discussed. As compared to silane and silicon tetrachloride, an anomalous error in the absolute energy is reported for the L2,3-spectrum of silicon tetrafluoride, amounting to an additional spectral shift of ∼1 eV. This anomaly is also observed for other exchange-correlation functionals, but it is seen neither at other silicon edges nor at the carbon K-edge of fluorine derivatives of ethene. Considering the series of molecules SiH4-XFX with X = 1, 2, 3, 4, a gradual divergence from interpolated experimental ionization potentials is observed at the level of Kohn-Sham density functional theory (DFT), and to a smaller extent with the use of Hartree-Fock. This anomalous error is thus attributed partly to difficulties in correctly emulating the electronic structure effects imposed by the very electronegative fluorines, and partly due to inconsistencies in the spurious electron self-repulsion in DFT. Substitution with one, or possibly two, fluorine atoms is estimated to yield small enough errors to allow for reliable interpretations and predictions of L2,3-spectra of more complex and extended silicon-based systems.
Damping characteristics of reinforced concrete structures
International Nuclear Information System (INIS)
Hisano, M.; Nagashima, I.; Kawamura, S.
1987-01-01
Reinforced concrete structures in a nuclear power plant are not permitted to go far into the inelasticity generally, even when subjected to strong ground motion. Therefore it is important to evaluate the damping appropriately in linear and after cracking stage before yielding in the dynamic response analysis. Next three dampings are considered of reinforced concrete structures. 1) Internal damping in linear range material damping of concrete without cracks;2) Hysteretic damping in inelastic range material hysteretic damping of concrete due to cracking and yielding;3) Damping due to the energy dissipation into the ground. Among these damping material damping affects dynamic response of a nuclear power plant on hard rock site where damping due to energy dissipation into the ground is scarcely expected. However material damping in linear and slightly nonlinear range have only been assumed without enough experimental data. In this paper such damping is investigated experimentally by the shaking table tests of reinforced concrete box-walls which modeled roughly the outer wall structure of a P.W.R. type nuclear power plant
Livesey, Michael; Horneff, John G; Sholder, Daniel; Lazarus, Mark; Williams, Gerald; Namdari, Surena
2018-05-01
A well-functioning rotator cuff is necessary for successful anatomic total shoulder arthroplasty (TSA). This study evaluated patients who underwent concomitant TSA and rotator cuff repair (RCR) for functional outcomes, revision rates, and predictors of poor results. Retrospective chart review was conducted to identify patients who underwent TSA and RCR. Demographic data, rotator cuff tear and RCR characteristics, range of motion, and radiographs were recorded. Minimum 2-year functional outcomes were obtained. Predictors of reoperation and/or poor clinical results were determined. Forty-five patients met inclusion criteria (22 high-grade partial-thickness and 23 full-thickness tears). Fourteen (31%) patients were labeled as having a poor result; 8 (18%) patients required reoperation. There was a significant difference between the acromiohumeral interval preoperatively and immediately postoperatively (P=.013). However, at maximum radiographic follow-up, the acromiohumeral interval was not significantly different from preoperative values (P=.86). Patients with a preoperative acromiohumeral interval of less than 8 mm had an increased rate of cuff-related reoperation (P=.003). Although concomitant TSA and RCR is a reasonable consideration, 31% of patients had a poor clinical result. An acromiohumeral interval of less than 8 mm was a predictor of cuff-related reoperation and may be an indication to consider reverse arthroplasty in the setting of joint arthrosis with a rotator cuff tear. [Orthopedics. 2018; 41(3):e334-e339.]. Copyright 2018, SLACK Incorporated.
Total reflection coefficients of low-energy photons presented as universal functions
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Ljubenov Vladan
2010-01-01
Full Text Available The possibility of expressing the total particle and energy reflection coefficients of low-energy photons in the form of universal functions valid for different shielding materials is investigated in this paper. The analysis is based on the results of Monte Carlo simulations of photon reflection by using MCNP, FOTELP, and PENELOPE codes. The normal incidence of the narrow monoenergetic photon beam of the unit intensity and of initial energies from 20 keV up to 100 keV is considered, and particle and energy reflection coefficients from the plane homogenous targets of water, aluminum, and iron are determined and compared. The representations of albedo coefficients on the initial photon energy, on the probability of large-angle photon scattering, and on the mean number of photon scatterings are examined. It is found out that only the rescaled albedo coefficients dependent on the mean number of photon scatterings have the form of universal functions and these functions are determined by applying the least square method.
Pritchett, James W
2015-07-01
One of the goals of a TKA is to approximate the function of a normal knee. Preserving the natural ligaments might provide a method of restoring close to normal function. Sacrifice of the ACL is common and practical during a TKA. However, this ligament is functional in more than 60% of patients undergoing a TKA and kinematic studies support the concept of bicruciate-retaining (that is, ACL-preserving) TKA; however, relatively few studies have evaluated patients treated with bicruciate-retaining TKA implants. I asked: (1) what is the long-term (minimum 20-year) survivorship, (2) what are the functional results, and (3) what are the reasons for revision of bicruciate-retaining knee arthroplasty prostheses? From January 1989 to September 1992, I performed 639 total knee replacements in 537 patients. Of these, 489 were performed in 390 patients using a bicruciate-retaining, minimally constrained device. During the period in question, this knee prosthesis was used for all patients observed intraoperatively to have an intact, functional ACL with between 15° varus and 15° valgus joint deformity. There were 234 women and 156 men with a mean age at surgery of 65 years (range, 42-84 years) and a primary diagnosis of osteoarthritis in 89%. The patella was resurfaced in all knees. The mean followup was 23 years (range, 20-24 years). At the time of this review, 199 (51%) patients had died and 31 (8%) patients were lost to followup, leaving 160 (41%) patients (214 knees) available for review. Component survivorship was determined by competing-risks analysis and Kaplan Meier survivorship analysis with revision for any reason as the primary endpoint. Patients were evaluated every 2 years to assess ROM, joint laxity, knee stability, and to determine American Knee Society scores. The Kaplan-Meier survivorship was 89% (95% CI, 82%-93%) at 23 years with revision for any reason as the endpoint. Competing-risks survivorship was 94% (95% CI, 91%%-96 %) at 23 years. At followup, the mean
STUDY OF FUNCTIONAL RESULTS OF CEMENTED TOTAL HIP REPLACEMENT BY MOORE’S APPROACH
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Arunim
2016-02-01
Full Text Available INTRODUCTION The total hip replacement (THR has probably become the surgical procedure of choice for vide variety of hip joint disabling diseases. The prosthesis used for THR is often grouped into cemented, cement-less and hybrid ones. There has been increasing trends in use of cement-less components citing more number of complications namely loosening, increased infection rate etc. however with additional cost factors as well. We conducted this study to ascertain whether in a developing country like ours should we really switch over to un-cemented hip replacements dreading such complications or can we still use cemented prosthesis with equally good if not better results. METHODS A study of functional results of cemented total hip replacement was done in patients with varied age groups ranging from 40 years to 75 years with the average age being 54.8 years. 20 patients with 21 diseased hips were treated with cemented total hip replacement by Moore’s posterior approach at NSCB Subharti medical college, Meerut, UP from December 2010 to December 2013 and reviewed thereafter with an average follow-up period of 4.2 years. Average surgical time required was one and half hour. Patients were asked to come for follow up on 1st month, 3rd month and 6th month and then every 6 months and were assessed as per modified Harris Hip Score. RESULTS All the patients were evaluated according to the Modified Harris Hip Scoring system. The results showed 14(67% hips with excellent results, 4(19% with good results, and 3(14% hips with fair results. No poor outcome was noted in this study. 2 cases of dislocation (10% were noted one on the 5th post-operative day and the other occurred after the patient was discharged from the institution. CONCLUSIONS The management of diseased and destroyed hips with chronic pain with cemented total hip replacement is effective and gives stable, mobile and painless hip joint to the patient. Functional results are excellent and
Sound Power Minimization of Circular Plates Through Damping Layer Placement
Wodtke, H.-W.; Lamancusa, J. S.
1998-09-01
Damping layers, widely used for noise and vibration control of thin-walled structures, can be designed to provide an optimal trade-off between performance and weight which is of particular importance in the automotive and aircraft industry. The goal of the presented work is the minimization of sound power radiated from plates under broadband excitation by redistribution of unconstrained damping layers. The total radiated sound power is assumed to be represented by the sound power radiated at the structural resonances. Resonance tracking is performed by means of single-degree-of-freedom (SDOF)-approximations based on near-resonance responses and their frequency derivatives. Axisymmetric vibrations of circular plates under several boundary and forcing conditions are considered. Frequency dependent Young's modulus and loss factor of the damping material are taken into account. Vibration analysis is based on the finite element method (FEM) while acoustic radiation is treated by means of Rayleigh's integral formula. It is shown that, starting from a uniform damping layer distribution, substantial reduction in radiated sound power can be achieved through redistribution of the damping layers. Depending on the given situation, these reductions are not only due to amplitude reductions but also to changes in vibration shapes and frequencies.
Transit-Time Damping, Landau Damping, and Perturbed Orbits
Simon, A.; Short, R. W.
1997-11-01
Transit-time damping(G.J. Morales and Y.C. Lee, Phys. Rev. Lett. 33), 1534 (1974).*^,*(P.A. Robinson, Phys. Fluids B 3), 545 (1991).** has traditionally been obtained by calculating the net energy gain of transiting electrons, of velocity v, to order E^2* in the amplitude of a localized electric field. This necessarily requires inclusion of the perturbed orbits in the equation of motion. A similar method has been used by others(D.R. Nicholson, Introduction to Plasma Theory) (Wiley, 1983).*^,*(E.M. Lifshitz and L.P. Pitaevskifi, Physical Kinetics) (Pergamon, 1981).** to obtain a ``physical'' picture of Landau damping in a nonlocalized field. The use of perturbed orbits seems odd since the original derivation of Landau (and that of Dawson) never went beyond a linear picture of the dynamics. We introduce a novel method that takes advantage of the time-reversal invariance of the Vlasov equation and requires only the unperturbed orbits to obtain the result. Obviously, there is much reduction in complexity. Application to finite slab geometry yields a simple expression for the damping rate. Equivalence to much more complicated results^2* is demonstrated. This method allows us to calculate damping in more complicated geometries and more complex electric fields, such as occur in SRS in filaments. See accompanying talk.(R.W. Short and A. Simon, this conference.) This work was supported by the U.S. DOE Office of Inertial Confinement Fusion under Co-op Agreement No. DE-FC03-92SF19460.
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Dionne Clermont E
2009-05-01
Full Text Available Abstract Background Recent evidences show that education and rehabilitation while waiting for knee replacement have positive effects on the patients' health status. Identification of factors associated with worse pain, function and health-related quality of life (HRQoL while waiting for surgery could help develop pre-surgery rehabilitation interventions that target specifically these factors and prioritize patients that may benefit the most from them. The objectives of this study were to measure pain, stiffness, function and HRQoL in patients at enrolment on waiting lists for knee replacement and to identify demographic, clinical, socioeconomic and psychosocial characteristics associated with these outcomes. Methods This study is part of a broader study measuring the effects of pre-surgery wait in patients scheduled for knee replacement. From 02/2006 to 09/2007, 197 patients newly scheduled for total knee replacement were recruited from the waiting lists of three university hospitals in Quebec City, Canada. Pain, stiffness and function were measured with the Western Ontario and McMaster Osteoarthritis Index (WOMAC and HRQoL was measured with the SF-36 Health Survey. Stepwise multiple regression analysis was used to assess the strength of the associations between the independent variables and the WOMAC and SF-36 scores. Results The scores of all eight HRQoL physical and mental domains of the SF-36 were significantly lower than aged matched Canadian normative data (p Conclusion Patients waiting for knee replacement have poor function and HRQoL. Characteristics that were found to be associated with these outcomes could help develop pre-surgery rehabilitation program and prioritize patients that may benefit the most from them. Such programs could include interventions to reduce psychological distress, therapeutic exercises targeting both knees and weight loss management.
International Nuclear Information System (INIS)
Hintermüller, Michael; Rautenberg, Carlos N; Hahn, Jooyoung
2014-01-01
Variable splitting schemes for the function space version of the image reconstruction problem with total variation regularization (TV-problem) in its primal and pre-dual formulations are considered. For the primal splitting formulation, while existence of a solution cannot be guaranteed, it is shown that quasi-minimizers of the penalized problem are asymptotically related to the solution of the original TV-problem. On the other hand, for the pre-dual formulation, a family of parametrized problems is introduced and a parameter dependent contraction of an associated fixed point iteration is established. Moreover, the theory is validated by numerical tests. Additionally, the augmented Lagrangian approach is studied, details on an implementation on a staggered grid are provided and numerical tests are shown. (paper)
Loss of P53 Function in Colon Cancer Cells Results in Increased Phosphocholine and Total Choline
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Noriko Mori
2004-10-01
Full Text Available Mutations in the p53 gene are the most frequently observed genetic lesions in human cancers. Human cancers that contain a p53 mutation are more aggressive, more apt to metastasize, and more often fatal. p53 controls numerous downstream targets that can influence various outcomes such as apoptosis, growth arrest, and DNA repair. Based on previous observations using 1H magnetic resonance spectroscopy (MRS, we have identified choline phospholipid metabolite intensities typical of increased malignancy. Here we have used 1H MRS to characterize the choline phospholipid metabolite levels of p53+/+ and p53−/– cells, and demonstrated that loss of p53 function results in increased phosphocholine and total choline. These data suggest that the increased malignancy of cancer cells resulting from loss of p53 may be mediated, in part, through the choline phospholipid pathway.
The influence of obesity on functional outcome and quality of life after total knee arthroplasty.
Xu, S; Chen, J Y; Lo, N N; Chia, S L; Tay, D K J; Pang, H N; Hao, Y; Yeo, S J
2018-05-01
Aims This study investigated the influence of body mass index (BMI) on patients' function and quality of life ten years after total knee arthroplasty (TKA). Patients and Methods A total of 126 patients who underwent unilateral TKA in 2006 were prospectively included in this retrospective study. They were categorized into two groups based on BMI: Quality of life was assessed using the Physical (PCS) and Mental Component Scores (MCS) of the 36-Item Short-Form Health Survey. Results Patients in the obese group underwent TKA at a younger age (mean, 63.0 years, sd 8.0) compared with the control group (mean, 65.6 years, sd 7.6; p = 0.03). Preoperatively, both groups had comparable functional and quality-of-life scores. Ten years postoperatively, the control group had significantly higher OKS and MCS compared with the obese group (OKS, mean 18 (sd 5) vs mean 22 (sd 10), p = 0.03; MCS, mean 56 (sd 10) vs mean 50 (sd 11), p = 0.01). After applying multiple linear regression with the various outcomes scores as dependent variables and age, gender, and Charlson Comorbidity Index as independent variables, there was a clear association between obesity and poorer outcome in KSFS, OKS, and MCS at ten years postoperatively (p quality of life postoperatively, obese patients tend to have smaller improvements in the OKS and MCS ten years postoperatively. It is important to counsel patients on the importance of weight management to achieve a more sustained outcome after TKA. Cite this article: Bone Joint J 2018;100-B:579-83.
Functional brain imaging of a complex navigation task following one night of total sleep deprivation
Strangman, Gary; Thompson, John H.; Strauss, Monica M.; Marshburn, Thomas H.; Sutton, Jeffrey P.
2006-01-01
Study Objectives: To assess the cerebral effects associated with sleep deprivation in a simulation of a complex, real-world, high-risk task. Design and Interventions: A two-week, repeated measures, cross-over experimental protocol, with counterbalanced orders of normal sleep (NS) and total sleep deprivation (TSD). Setting: Each subject underwent functional magnetic resonance imaging (fMRI) while performing a dual-joystick, 3D sensorimotor navigation task (simulated orbital docking). Scanning was performed twice per subject, once following a night of normal sleep (NS), and once following a single night of total sleep deprivation (TSD). Five runs (eight 24s docking trials each) were performed during each scanning session. Participants: Six healthy, young, right-handed volunteers (2 women; mean age 20) participated. Measurements and Results: Behavioral performance on multiple measures was comparable in the two sleep conditions. Neuroimaging results within sleep conditions revealed similar locations of peak activity for NS and TSD, including left sensorimotor cortex, left precuneus (BA 7), and right visual areas (BA 18/19). However, cerebral activation following TSD was substantially larger and exhibited higher amplitude modulations from baseline. When directly comparing NS and TSD, most regions exhibited TSD>NS activity, including multiple prefrontal cortical areas (BA 8/9,44/45,47), lateral parieto-occipital areas (BA 19/39, 40), superior temporal cortex (BA 22), and bilateral thalamus and amygdala. Only left parietal cortex (BA 7) demonstrated NS>TSD activity. Conclusions: The large network of cerebral differences between the two conditions, even with comparable behavioral performance, suggests the possibility of detecting TSD-induced stress via functional brain imaging techniques on complex tasks before stress-induced failures.
Directory of Open Access Journals (Sweden)
Afshin Taheriazam
2016-06-01
Full Text Available Total hip arthroplasty (THA is one of the successful and cost-benefit surgical treatments. One-stage bilateral THA (BTHA offers many benefits. However, there are concerns about the safety of the procedure and higher complications. We aimed to evaluate the complications and outcomes of one-stage BTHA with Hardinge approach for femoral head avascular necrosis patients. A total of 60 patients from April 2009 and May 2013, were underwent one-stage bilateral total hip arthroplasty (BTHA in Milad and Erfan hospitals, Tehran, Iran. A prospective analysis of the functional outcomes and complications of one-stage BTHA through Hardinge approach in patients with femoral head avascular necrosis (AVN performed. We evaluated all patients clinically and radiologically with serial follow-ups. A clinical hip score based upon the modified Harris Hip Score (MHHS was performed preoperatively and again postoperatively. During period of study 44 men (73.3% and 16 women (26.6% with a mean age of 31.40±4.08 years (range 25 to 36 years at the time of presentation were entered. The mean surgical time was 2.6±0.38 hrs. The mean hospital stay was 3 .50±0.72 days. Hemoglobin level decreased significa ntly after operation (P= 0.046. There was no reported patient with perioperative death, deep venous thrombosis, pulmonary embolism, infection, dislocation, periprosthetic fracture or heterotrophic ossification. The mean preoperative MHHS score was 47.93±7.33 in patients. MHHS score i mproved to 95.06±3.47 in the last follow-up (P=0.0001.Our results recommend the use of one-stage BTHA through Hardinge approach in femoral head avascular necrosis patients.
Development of new damping devices for piping
International Nuclear Information System (INIS)
Kobayashi, Hiroe
1991-01-01
An increase of the damping ratio is known to be very effective for the seismic design of a piping system. Increasing the damping ratio and reducing the seismic response of the piping system, the following three types of damping devices for piping systems are introduced: (1) visco-elastic damper, (2) elasto-plastic damper and (3) compact dynamic damper. The dynamic characteristics of these damping devices were investigated by the component test and the applicability of them to the piping system was confirmed by the vibration test using a three dimensional piping model. These damping devices are more effective than mechanical snubbers to reduce the vibration of the piping system. (author)
Araújo, Paulo; Machado, Luís; Cadavez, Duarte; Mónaco, Lisete; Januário, Filipa; Luís, Lisete; Bártolo, Mafalda
2017-09-29
To assess the function and quality of life in patients undergoing total hip arthroplasty distinguishing two surgical approaches (posterior / anterolateral) used by the Orthopedics department of Centro Hospitalar de Leiria. Retrospective study of 94 patients subject to unilateral hip replacement surgery, using the 'Hip Osteoarthritis Outcome Score' (HOOS LK 2.0) questionnaire, the Trendelenburg test and evaluation of muscle strength of the hip abductor muscles with dynamometer. Patients were evaluated at six months, 12 months, 18 months and 24 months after surgery. The study revealed that 97.9% patients completed the rehabilitation program. The postoperative evolution (six to 24 months) does not appear to have any differences in results when comparing both approaches. At six months the patient operated by the anterolateral approach showed worse results when compared with the posterior approach, in particular in Hip Osteoarthritis Outcome Score pain, in Hip Osteoarthritis Outcome Score symptoms and Hip Osteoarthritis Outcome Score activities of daily living. After 24 months, no differences between the two surgical approaches were found. Of the 94 patients evaluated, the Trendelenburg test was positive in 31% of patients of which 81.9% corresponds to patients operated by the anterolateral approach. Muscle strength of the abductors of the operated hip was clearly lower in the anterolateral approach at six months, 12 months, and 24 months. This study showed that, in the first six months after total hip arthroplasty, the patients operated by the posterior approach were, according to the HOOS questionnaire, less symptomatic, and presented with better quality of life and less impact on activities of daily living and in sport and leisure when compared with the patients operated by the anterolateral approach. However, these differences were matched over the 24 months. Moreover, the results of muscle strength of the abductor muscles of the hip were clearly superior in
Analysis of in vitro and in vivo function of total knee replacements using dynamic contact models
Zhao, Dong
Despite the high incidence of osteoarthritis in human knee joint, its causes remain unknown. Total knee replacement (TKR) has been shown clinically to be effective in restoring the knee function. However, wear of ultra-high molecular weight polyethylene has limited the longevity of TKRs. To address these important issues, it is necessary to investigate the in vitro and in vivo function of total knee replacements using dynamic contact models. A multibody dynamic model of an AMTI knee simulator was developed. Incorporating a wear prediction model into the contact model based on elastic foundation theory enables the contact surface to take into account creep and wear during the dynamic simulation. Comparisons of the predicted damage depth, area, and volume lost with worn retrievals from a physical machine were made to validate the model. In vivo tibial force distributions during dynamic and high flexion activities were investigated using the dynamic contact model. In vivo medial and lateral contact forces experienced by a well-aligned instrumented knee implant, as well as upper and lower bounds on contact pressures for a variety of activities were studied. For all activities, the predicted medial and lateral contact forces were insensitive to the selected material model. For this patient, the load split during the mid-stance phase of gait and during stair is more equal than anticipated. The external knee adduction torque has been proposed as a surrogate measure for medial compartment load during gait. However, a direct link between these two quantities has not been demonstrated using in vivo measurement of medial compartment load. In vivo data collected from a subject with an instrumented knee implant were analyzed to evaluate this link. The subject performed five different overground gait motions (normal, fast, slow, wide, and toe out) while instrumented implant, video motion, and ground reaction data were simultaneously collected. The high correlation coefficient
Quality of life and functionality after non-cemented total hiparthroplasty
International Nuclear Information System (INIS)
Shah, Z.A.; Arif, U.; Aslam, M.N.; Bilal, A.; Khan, M.N.B.
2013-01-01
Objectives: To evaluate the functional outcome of non-cemented total hip arthroplasty in terms of pain relief, functional capacity, range of motion and absence of deformity using Harris hip score. Study Design: Descriptive study. Place and Duration of Study: From January 2012 to December 2012, at Nawaz Sharif Social Security Teaching Hospital, Lahore (University College Medicine and Dentistry). Subject and Methods: Thirty patients meeting the inclusion criteria were admitted through orthopedics outpatient department of Nawaz Sharif social security hospital Lahore. Pre operative Harris scoring was done and was compared with the post operative score to find the improvement. Results: Mean age of patients was 52.53 +- 18.21 years, and 17 were males and 13 females. Average pre operative Harris Hip score was 23.77 +- 9.50 and post-operative score 87.90 +- 10.42. Conclusion: It was concluded that THR is a safe surgical procedure with promising results in relieving pain, improving movements and upgrading the quality of life. (author)
Energy dependence of the emittance of damping ring beams
International Nuclear Information System (INIS)
Stiening, R.
1985-01-01
The energy at which the SLC damping rings are operated was chosen to be 1.21 GeV. At the time that that specification was made, the repetition rate of the SLC was expected to be 180 Hz. It is now anticipated that the repetition rate during the initial year of operation of the SLC will be 120 Hz. The following curves which show the output emittance of the damping rings as a function of input emittance and energy suggest that there is a range of energies over which the rings can be operated without changing the SLC luminosity. It should be noted that in the era of polarized beams, the damping ring energy will be fixed at the design value on account of the spin precession required in the LTR and RTL transport lines. The SLC design output emittance of the damping rings is 3 x 10 -5 radian-meters. Because of space charge disruption and quantum emission downstream of the damping rings, much lower values than the design value may not have a large beneficial effect on the luminosity. 3 figures
Route Flap Damping Made Usable
Pelsser, Cristel; Maennel, Olaf; Mohapatra, Pradosh; Bush, Randy; Patel, Keyur
The Border Gateway Protocol (BGP), the de facto inter-domain routing protocol of the Internet, is known to be noisy. The protocol has two main mechanisms to ameliorate this, MinRouteAdvertisementInterval (MRAI), and Route Flap Damping (RFD). MRAI deals with very short bursts on the order of a few to 30 seconds. RFD deals with longer bursts, minutes to hours. Unfortunately, RFD was found to severely penalize sites for being well-connected because topological richness amplifies the number of update messages exchanged. So most operators have disabled it. Through measurement, this paper explores the avenue of absolutely minimal change to code, and shows that a few RFD algorithmic constants and limits can be trivially modified, with the result being damping a non-trivial amount of long term churn without penalizing well-behaved prefixes' normal convergence process.
Directory of Open Access Journals (Sweden)
M. P. Zinoviev
2017-01-01
Full Text Available Purpose of the study – to evaluate the influence of residual varus deformity of the lower leg on clinical, functional and dynamometric outcomes of TKR.Material and methods. In the period from September 2014 till May 2015 951 total knee replacement surgeries were performed in Ural clinical and rehabilitation center in 933 patients with initial varus deformity of lower limb. However, in 52 cases (5.5% residual varus deformity of >3° persisted. The main group included 36 patients with mean residual varus deformity of lower leg of 3.9°±0.74° (from 3.1° to 5.6°, the control group included 34 patients with neutral mechanic axis of the lower leg. Evaluation of treatment outcomes was performed on average 14.2±1.8 months after the procedure using functional assessment of the patients according to KSS (Knee Society Score, subjective assessment of life quality (SF36, as well as evaluation of the static-dynamic function of the lower leg on diagnostic and treatment complex Biodex Systems 4 Quick Set and assessment of stability of components fixation by F.C. Ewald scale in modification of O.A. Kudinov et al.Results. Functional assessment of the patients according to KSS (Knee Society Score for the main group was 84.0±4.6, in control group – 82.2±4.1 points (p>0.05. Subjective assessment of life quality (SF36 in the main group was 162.6±6.4 points, in control group – 164.3±8.1 points (p>0.05. In terms of flexion and extension of lower leg there were no significant differences between two groups when assessing static and dynamic function by treatment and diagnostic complex «Biodex Systems 4 Quick Set» on average in 14.2±1.8 months after procedure: neither isometric nor isokinetic parameters in both groups demonstrated statistically significant differences (p>0.05. Based on X-rays evaluation there were no abnormalities in components fixation in both groups. There were no statistically significant differences identified in KSS and SF36 scales
Energy Technology Data Exchange (ETDEWEB)
Pohl, F.; Seufert, J.; Flentje, M.; Koelbl, O. [Wuerzburg Univ. (Germany). Dept. of Radiotherapy; Tauscher, A.; Springorum, H.W. [Caritas Krankenhaus Bad Mergentheim (Germany). Orthopedic Clinic; Lehmann, H. [Caritas Krankenhaus Bad Mergentheim (Germany). Inst. of Radiology
2005-08-01
Purpose: The functional failure induced by heterotopic ossification (HO) following total hip arthroplasty (THA) was analyzed and correlated to the radiologic failure. Patients and methods: From July 1997 to July 2001, 315 patients (345 hips) received THA indicated by a hypertrophic osteoarthritis of higher degree (Kellgren grade III, IV). All patients were irradiated prophylactically for prevention of HO on the evening before surgery with a 7-Gy single fraction. The patients' median age was 66.3 years. Radiologic failure was assessed by comparison of pre- and postoperative hip X-rays (immediately and 6 months after surgery). Analysis of radiographs was performed according to the Brooker Score. Clinical failure was appraised by measurement of passive range of motion (ROM) of the hip joint with a standard goniometer. The t-test was used for statistical analysis. Results: 281 patients (81.5%) did not develop HO. HO of Brooker grade I or II was found in 58 patients (16.8%). Six patients (1.7%) developed HO Brooker grade III or IV. There was a significant negative correlation between the degree of radiologic and clinical failure. ROM differed significantly between patients with HO Brooker grade 0, I, II and patients with HO Brooker grade III, IV. Comparing the pre- and postoperative ROM, all patients with Brooker grade 0, I and II showed a significant improvement of flexion, internal and external rotation, abduction and adduction movement. Patients with HO Brooker grade III and IV showed no improvement of ROM in the postoperative follow-up. Conclusion: The development of HO following THA influences the physical function of the hip joint dependent on the degree of ossification. HO of lower degree (Brooker I, II) does not influence the clinical outcome, whereas HO of higher degree (Brooker III, IV) reduces the function of hip arthroplasty. Therefore, the purpose of a prophylactic therapy must be to reduce HO of higher degree. (orig.)
Directory of Open Access Journals (Sweden)
Abidin 1
2001-08-01
Full Text Available In the product design and development processes, Quality Function Deployment (QFD provides a comprehensive, systematic approach to ensure that the products meet or exceed customer expectations. This paper reports the results of vegetables customers survey in Jakarta. Analytical Hierarchy Process (AHP method was used for weighing the result of survey, and the customer expectation were translated using QFD. To meet the biggest customer expectation, i.e. vegetables freshness, Just In Time (JIT concept was utilized.
Modelling of Dampers and Damping in Structures
DEFF Research Database (Denmark)
Høgsberg, Jan Riess
2006-01-01
and the maximum attainable damping are found by maximizing the expression for the damping ratio. The theory is formulated for linear damper models, but may also be applied for non-linear dampers in terms of equivalent linear parameters for stiffness and damping, respectively. The format of the expressions......, and thereby the damping, of flexible structures are generally described in terms of the dominant vibration modes. A system reduction technique, where the damped vibration mode is constructed as a linear combination of the undamped mode shape and the mode shape obtained by locking the damper, is applied....... This two-component representation leads to a simple solution for the modal damping representing the natural frequency and the associated damping ratio. It appears from numerical examples that this system reduction technique provides very accurate results. % Analytical expressions for the optimal tuning...
Sheath waves, non collisional dampings
International Nuclear Information System (INIS)
Marec, Jean Lucien Ernest
1974-01-01
When a metallic conductor is inserted into an ionised gas, an area of electron depletion is formed between the conductor and the plasma: the ionic sheath. Moreover, if the conductor is excited by an electric field, this ionic sheath plays an important role with respect to microwave properties. In this research thesis, the author addresses the range of frequencies smaller than the plasma frequency, and reports the study of resonance phenomena. After a presentation of the problem through a bibliographical study, the author recalls general characteristics of sheath wave propagation and of sheath resonances, and discusses the validity of different hypotheses (for example and among others, electrostatic approximations, cold plasma). Then, the author more particularly addresses theoretical problems related to non collisional dampings: brief bibliographical study, detailed presentation and description of the theoretical model, damping calculation methods. The author then justifies the design and performance of an experiment, indicates measurement methods used to determine plasma characteristics as well as other magnitudes which allow the description of mechanisms of propagation and damping of sheath waves. Experimental results are finally presented with respect to various parameters. The author discusses to which extent the chosen theoretical model is satisfying [fr
The stability of a class of synchronous generator damping model
Liu, Jun
2018-03-01
Electricity is indispensable to modern society and the most convenient energy, it can be easily transformed into other forms of energy, has been widely used in engineering, transportation and so on, this paper studied the generator model with damping machine, using the Lyapunov function method, we obtain sufficient conditions for the asymptotic stability of the model.
Structural Damping with Friction Beams
Directory of Open Access Journals (Sweden)
L. Gaul
2008-01-01
Full Text Available In the last several years, there has been increasing interest in the use of friction joints for enhancing damping in structures. The joints themselves are responsible for the major part of the energy dissipation in assembled structures. The dissipated work in a joint depends on both the applied normal force and the excitation force. For the case of a constant amplitude excitation force, there is an optimal normal force which maximizes the damping. A ‘passive’ approach would be employed in this instance. In most cases however, the excitation force, as well as the interface parameters such as the friction coefficient, normal pressure distribution, etc., are not constant. In these cases, a ‘semi-active’ approach, which implements an active varying normal force, is necessary. For the ‘passive’ and ‘semi-active’ approaches, the normal force has to be measured. Interestingly, since the normal force in a friction joint influences the local stiffness, the natural frequencies of the assembled structure can be tuned by adjusting the normal force. Experiments and simulations are performed for a simple laboratory structure consisting of two superposed beams with friction in the interface. Numerical simulation of the friction interface requires non-linear models. The response of the double beam system is simulated using a numerical algorithm programmed in MATLAB which models point-to-point friction with the Masing friction model. Numerical predictions and measurements of the double beam free vibration response are compared. A practical application is then described, in which a friction beam is used to damp the vibrations of the work piece table on a milling machine. The increased damping of the table reduces vibration amplitudes, which in turn results in enhanced surface quality of the machined parts, reduction in machine tool wear, and potentially higher feed rates. Optimal positioning of the friction beams is based on knowledge of the mode
Damping of Resonantly Forced Density Waves in Dense Planetary Rings
Lehmann, Marius; Schmidt, Jürgen; Salo, Heikki
2016-10-01
We address the stability of resonantly forced density waves in dense planetary rings.Already by Goldreich and Tremaine (1978) it has been argued that density waves might be unstable, depending on the relationship between the ring's viscosity and the surface mass density. In the recent paper (Schmidt et al. 2016) we have pointed out that when - within a fluid description of the ring dynamics - the criterion for viscous overstability is satisfied, forced spiral density waves become unstable as well. In this case, linear theory fails to describe the damping.We apply the multiple scale formalism to derive a weakly nonlinear damping relation from a hydrodynamical model.This relation describes the resonant excitation and nonlinear viscous damping of spiral density waves in a vertically integrated fluid disk with density dependent transport coefficients. The model consistently predicts linear instability of density waves in a ring region where the conditions for viscous overstability are met. In this case, sufficiently far away from the Lindblad resonance, the surface mass density perturbation is predicted to saturate to a constant value due to nonlinear viscous damping. In general the model wave damping lengths depend on a set of input parameters, such as the distance to the threshold for viscous overstability and the ground state surface mass density.Our new model compares reasonably well with the streamline model for nonlinear density waves of Borderies et al. 1986.Deviations become substantial in the highly nonlinear regime, corresponding to strong satellite forcing.Nevertheless, we generally observe good or at least qualitative agreement between the wave amplitude profiles of both models. The streamline approach is superior at matching the total wave profile of waves observed in Saturn's rings, while our new damping relation is a comparably handy tool to gain insight in the evolution of the wave amplitude with distance from resonance, and the different regimes of
Hakimzadeh, Nazanin; Elias, Joëlle; Wijntjens, Gilbert W M; Theunissen, Ruud; van Weert, Angela; Smulders, Martijn W; van den Akker, Nynke; Moerland, Perry D; Verberne, Hein J; Hoebers, Loes P; Henriques, Jose P S; van der Laan, Anja M; Ilhan, Mustafa; Post, Mark; Bekkers, Sebastiaan C A M; Piek, Jan J
2017-05-08
An expansive collateral artery network is correlated with improved survival in case of adverse cardiac episodes. We aimed to identify cellular microRNAs (miRNA; miR) important for collateral artery growth. Chronic total occlusion (CTO) patients (n = 26) were dichotomized using pressure-derived collateral flow index (CFI p ) measurements; high collateral capacity (CFI p > 0.39; n = 14) and low collateral (CFI p collateral capacity patients. Validation by real-time polymerase chain reaction demonstrated significantly decreased expression of miR339-5p in all stimulated monocyte phenotypes of low collateral capacity patients. MiR339-5p showed significant correlation with CFI p values in stimulated monocytes. Ingenuity pathway analysis of predicted gene targets of miR339-5p and differential gene expression data from high versus low CFI p patients (n = 20), revealed significant association with STAT3 pathway, and also suggested a possible regulatory role for this signaling pathway. These results identify a novel association between miR339-5p and coronary collateral function. Future work examining modulation of miR339-5p and downstream effects on the STAT3 pathway and subsequent collateral vessel growth are warranted.
International Nuclear Information System (INIS)
Davidson, A.; Pedersen, N.F.; Dueholm, B.
1985-01-01
We show some experimental results which suggest that total damping, including surface loss, plays a fundamental role in limiting the stability of high-velocity Sine-Gordon solitons in real Josephson tunnel junctions
DEFF Research Database (Denmark)
Davidson, A.; Pedersen, Niels Falsig; Dueholm, B.
1985-01-01
We show some experimental results which suggest that total damping, including surface loss, plays a fundamental role in limiting the stability of high-velocity sine-Gordon solitons in real Josephson tunnel junctions.......We show some experimental results which suggest that total damping, including surface loss, plays a fundamental role in limiting the stability of high-velocity sine-Gordon solitons in real Josephson tunnel junctions....
Hilton, Maren E; Gioe, Terence; Noorbaloochi, Siamak; Singh, Jasvinder A
2016-10-07
Previous studies suggested that pre-operative comorbidity was a risk factor for worse outcomes after TKA. To our knowledge, studies have not examined whether postoperative changes in comorbidity impact pain and function outcomes longitudinally. Our objective was to examine if increasing comorbidity postoperatively is associated with worsening physical function and pain after primary total knee arthroplasty (TKA). We performed a retrospective chart review of veterans who had completed Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Short Form-36 (SF36) surveys at regular intervals after primary TKA. Comorbidity was assessed using a variety of scales: validated Charlson comorbidity index score, and a novel Arthroplasty Comorbidity Severity Index score (Including medical index, local musculoskeletal index [including lower extremity and spine] and TKA-related index subscales; higher scores are worse ), at multiple time-points post-TKA. We used mixed model linear regression to examine the association of worsening comorbidity post-TKA with change in WOMAC and SF-36 scores in the subsequent follow-up periods, controlling for age, length of follow-up, and repeated observations. The study cohort consisted of 124 patients with a mean age of 71.7 years (range 58.6-89.2, standard deviation (SD) 6.9) followed for a mean of 4.9 years post-operatively (range 1.3-11.4; SD 2.8). We found that post-operative worsening of the Charlson Index score was significantly associated with worsening SF-36 Physical Function (PF) (beta coefficient (ß) = -0.07; p < 0.0001), SF-36 Bodily Pain (BP) (ß = -0.06; p = 0.002), and WOMAC PF subscale (ß = 0.08; p < 0.001; higher scores are worse) scores, in the subsequent periods. Worsening novel medical index subscale scores were significantly associated with worsening SF-36 PF scores (ß = -0.03; p = 0.002), SF-36 BP (ß = -0.04; p < 0.001) and showed a non-significant trend
Anisotropic damping of Timoshenko beam elements
Energy Technology Data Exchange (ETDEWEB)
Hansen, M.H.
2001-05-01
This report contains a description of a structural damping model for Timoshenko beam elements used in the aeroelastic code HawC developed at Risoe for modeling wind turbines. The model has been developed to enable modeling of turbine blades which often have different damping characteristics for flapwise, edgewise and torsional vibrations. The structural damping forces acting on the beam element are modeled by viscous damping described by an element damping matrix. The composition of this matrix is based on the element mass and stiffness matrices. It is shown how the coefficients for the mass and stiffness contributions can be calibrated to give the desired modal damping in the complete model of a blade. (au)
DEFF Research Database (Denmark)
Skovgaard, Christian; Holm, Bente; Troelsen, Anders
2013-01-01
Background and purpose Blood loss after total knee arthroplasty (TKA) may lead to anemia, blood transfusions, and increased total costs. Also, bleeding into the periarticular tissue may cause swelling and a reduction in quadriceps strength, thus impairing early functional recovery. In this random...... in TKA showed no benefit in reducing drain output or in facilitating early functional recovery when used with a tourniquet, tranexamic acid, and a femoral bone plug....
The impact of total sleep deprivation upon cognitive functioning in firefighters
Directory of Open Access Journals (Sweden)
Kujawski S
2018-05-01
Full Text Available Sławomir Kujawski,1 Joanna Słomko,1 Małgorzata Tafil-Klawe,2 Monika Zawadka-Kunikowska,1 Justyna Szrajda,1 Julia L Newton,3 Paweł Zalewski,1 Jacek J Klawe1 1Department of Hygiene, Epidemiology and Ergonomics, Nicolaus Copernicus University, Toruń, Poland; 2Department of Human Physiology, Nicolaus Copernicus University, Toruń, Poland; 3Institute for Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle-upon-Tyne, UK Introduction: Firefighters as a profession are required to maintain high levels of attention for prolonged periods. However, total sleep deprivation (TSD could influence negatively upon performance, particularly when the task is prolonged and repetitive. Purpose: The aim of this study is to examine the influence of TSD on cognitive functioning in a group of firefighters. Subjects and methods: Sixty volunteers who were active male fire brigade officers were examined with a computerized battery test that consisted of simple reaction time (SRT (repeated three times, choice reaction time, visual attention test, and delayed matching to sample. Six series of measurements were undertaken over a period of TSD. Results: Performance in the second attempt in SRT test was significantly worse in terms of increased number of errors and, consequently, decreased number of correct responses during TSD. In contrast, the choice reaction time number of correct responses as well as the visual attention test reaction time for all and correct responses significantly improved compared to initial time points. Conclusion: The study has confirmed that subjects committed significantly more errors and, consequently, noted a smaller number of correct responses in the second attempt of SRT test. However, the remaining results showed reversed direction of TSD influence. TSD potentially leads to worse performance in a relatively easy task in a group of firefighters. Errors during repetitive tasks in firefighting
Evaluation of total renal function from 99mTc-MAG3 scintigraphy in children
International Nuclear Information System (INIS)
Andersson, L.G.; Bratteby, L.E.; Takalo, R.; Svensson, L.
2002-01-01
Aim: The aim of the present study was to evaluate the usefulness of dynamic scintigraphy in the assessment of total renal function in children. The Patlak slope of 99m Tc-MAG3 renography curves were compared to the plasma clearance values of 51Cr-EDTA. Material and methods: The study sample consisted of 53 boys and 33 girls with various nephrologic disorders, referred for routine clinical reasons. The median age of the subjects was 5.1 years (range 0.3 - 14.1 years). Imaging procedure. In supine position, the patient received a bolus injection of 1 MBq/kg, (minimum 10 MBq) 99m Tc-MAG3 and a posterior dynamic gamma camera registration was performed for 21 min using 1 frame per second during the first minute and thereafter 10 seconds frames. Data analysis. Time-activity curves were generated from manually drawn heart and renal regions of interest. The MAG3 uptake was calculated from the Patlak-Rutland plot of each kidney by linear curve fitting until the beginning of the excretory phase. A sum of the slope values was used as a measure of total renal MAG3 uptake. Cr-EDTA clearance. Glomerular filtration rate (GFR) was measured from the plasma clearance of 51 Cr-EDTA using single injection, multiple-sample technique. After intravenous injection of 51 Cr-EDTA (74 kBq/kg for children up to 7 years, 37 kBq/kg for children older than 7 years), blood samples were drawn at 5, 10, 15, 45, 60, 120 and 180 min for radioactivity measurement. The GFR was calculated according to Broechner-Mortensen and expressed in ml/min. Results: The absolute 51 Cr-EDTA clearance varied from 9 to 143 ml/min. There was a close linear relationship between 51 Cr-EDTA clearance and MAG3 uptake (Fig). The correlation coefficient was 0.90 and the regression equation (y=43.5 x + 664). Conclusions: In the present study, there was a good correlation between plasma clearance of 51 Cr-EDTA and the sum of the Patlak slopes. The regression equation can be utilised to transform the 99m Tc-MAG3 uptake to an
Directory of Open Access Journals (Sweden)
Braun Werner
2002-11-01
Full Text Available Abstract Background Total sequence decomposition, using the web-based MASIA tool, identifies areas of conservation in aligned protein sequences. By structurally annotating these motifs, the sequence can be parsed into individual building blocks, molecular legos ("molegos", that can eventually be related to function. Here, the approach is applied to the apurinic/apyrimidinic endonuclease (APE DNA repair proteins, essential enzymes that have been highly conserved throughout evolution. The APEs, DNase-1 and inositol 5'-polyphosphate phosphatases (IPP form a superfamily that catalyze metal ion based phosphorolysis, but recognize different substrates. Results MASIA decomposition of APE yielded 12 sequence motifs, 10 of which are also structurally conserved within the family and are designated as molegos. The 12 motifs include all the residues known to be essential for DNA cleavage by APE. Five of these molegos are sequentially and structurally conserved in DNase-1 and the IPP family. Correcting the sequence alignment to match the residues at the ends of two of the molegos that are absolutely conserved in each of the three families greatly improved the local structural alignment of APEs, DNase-1 and synaptojanin. Comparing substrate/product binding of molegos common to DNase-1 showed that those distinctive for APEs are not directly involved in cleavage, but establish protein-DNA interactions 3' to the abasic site. These additional bonds enhance both specific binding to damaged DNA and the processivity of APE1. Conclusion A modular approach can improve structurally predictive alignments of homologous proteins with low sequence identity and reveal residues peripheral to the traditional "active site" that control the specificity of enzymatic activity.
An Empirical Method for Particle Damping Design
Directory of Open Access Journals (Sweden)
Zhi Wei Xu
2004-01-01
Full Text Available Particle damping is an effective vibration suppression method. The purpose of this paper is to develop an empirical method for particle damping design based on extensive experiments on three structural objects – steel beam, bond arm and bond head stand. The relationships among several key parameters of structure/particles are obtained. Then the procedures with the use of particle damping are proposed to provide guidelines for practical applications. It is believed that the results presented in this paper would be helpful to effectively implement the particle damping for various structural systems for the purpose of vibration suppression.
Phenomenology of chiral damping in noncentrosymmetric magnets
Akosa, Collins Ashu; Miron, Ioan Mihai; Gaudin, Gilles; Manchon, Aurelien
2016-01-01
A phenomenology of magnetic chiral damping is proposed in the context of magnetic materials lacking inversion symmetry. We show that the magnetic damping tensor acquires a component linear in magnetization gradient in the form of Lifshitz invariants. We propose different microscopic mechanisms that can produce such a damping in ferromagnetic metals, among which local spin pumping in the presence of an anomalous Hall effect and an effective “s-d” Dzyaloshinskii-Moriya antisymmetric exchange. The implication of this chiral damping in terms of domain-wall motion is investigated in the flow and creep regimes.
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.
Phenomenology of chiral damping in noncentrosymmetric magnets
Akosa, Collins Ashu
2016-06-21
A phenomenology of magnetic chiral damping is proposed in the context of magnetic materials lacking inversion symmetry. We show that the magnetic damping tensor acquires a component linear in magnetization gradient in the form of Lifshitz invariants. We propose different microscopic mechanisms that can produce such a damping in ferromagnetic metals, among which local spin pumping in the presence of an anomalous Hall effect and an effective “s-d” Dzyaloshinskii-Moriya antisymmetric exchange. The implication of this chiral damping in terms of domain-wall motion is investigated in the flow and creep regimes.
DEFF Research Database (Denmark)
Koukoura, Christina; Natarajan, Anand; Vesth, Allan
2015-01-01
damping from the decaying time series. The Enhanced Frequency Domain Decomposition (EFDD) method was applied to the wind turbine response under ambient excitation, for estimation of the damping in normal operation. The aero-servo-hydro-elastic tool HAWC2 is validated with offshore foundation load...... maxima of an impulse response caused by a boat impact. The result is used in the verification of the non aerodynamic damping in normal operation for low wind speeds. The auto-correlation function technique for damping estimation of a structure under ambient excitation was validated against the identified...... measurements. The model was tuned to the damping values obtained from the boat impact to match the measured loads. Wind turbulence intensity and wave characteristics used in the simulations are based on site measurements. A flexible soil model is included in the analysis. The importance of the correctly...
DEFF Research Database (Denmark)
Yao, Wei; Fang, Jiakun; Zhao, Ping
2013-01-01
the characteristics of the conventional PID, but adjust the parameters of PID controller online using identified Jacobian information from RBFNN. Hence, it has strong adaptability to the variation of the system operating condition. The effectiveness of the proposed controller is tested on a two-machine five-bus power...... system and a four-machine two-area power system under different operating conditions in comparison with the lead-lag damping controller tuned by evolutionary algorithm (EA). Simulation results show that the proposed damping controller achieves good robust performance for damping the low frequency......In this paper, a nonlinear adaptive damping controller based on radial basis function neural network (RBFNN), which can infinitely approximate to nonlinear system, is proposed for thyristor controlled series capacitor (TCSC). The proposed TCSC adaptive damping controller can not only have...
An evaluation of damping ratios for HVAC duct systems using vibration test data
International Nuclear Information System (INIS)
Gunyasu, K.; Horimizu, Y.; Kawakami, A.; Iokibe, H.; Yamazaki, T.
1988-01-01
The function of Heating Ventilating Air Conditioning (HVAC) systems must be maintained including HVAC duct systems to keep the operation of safety-related equipment in nuclear power plants during earthquake excitations. Therefore, it is important to carry out seismic design for HVAC duct systems. In the previous aseismic design for HVAC duct systems, the 0.5% damping ratio has been used in Japan. In recent years, vibration tests, held on actual duct systems in nuclear power plants and mockup duct systems were performed in order to investigate damping ratios for HVAC duct systems. Based on the results, it was confirmed that the damping ratio for HVAC duct systems, evaluated from these tests, were much greater than the 0.5% damping ratio used in the previous aseismic design of Japan. The new damping ratio in aseismic design was proposed to be 2.5%. The present paper describes the results of the above mentioned investigation
Directory of Open Access Journals (Sweden)
Ajay Puri
2012-01-01
Full Text Available Background: The extent of tumor may necessitate resection of the complete femur rarely to achieve adequate oncologic clearance in bone sarcomas. We present our experience with reconstruction in such cases using an indigenously manufactured, low-cost, total femoral prosthesis (TFP. We assessed the complications of the procedure, the oncologic and functional outcomes, and implant survival. Materials and Methods: Eight patients (four males and four females with a mean age of 32 years, operated between December 2003 and June 2009, had a TFP implanted. The diagnosis included osteogenic sarcoma (5, Ewing′s sarcoma (1, and chondrosarcoma (2. Mean followup was 33 months (9-72 months for all and 40 months (24-72 months in survivors. They were evaluated by Musculoskeletal Tumor Society score, implant survival as well as patient survival. Results: There was one local recurrence and five of seven patients are currently alive at the time of last followup. The Musculoskeletal Tumor Society score for patients ranged from 21 to 25 with a mean of 24 (80%. The implant survival was 88% at 5 years with only one TFP needing removal because of infection. Conclusions: A TFP in appropriately indicated patients with malignant bone tumors is oncologically safe. A locally manufactured, cost-effective implant provided consistent and predictable results after excision of the total femur with good functional outcomes.
Local functional derivative of the total energy and the shell structure in atoms and molecules
Pino, R.; Markvoort, Albert. J.; Santen, van R.A.; Hilbers, P.A.J.
2003-01-01
The full and local Thomas–Fermi–Dirac energy functional derivatives are evaluated at Hartree–Fock densities for several atoms and molecules. These functions are interpreted as local chemical potentials and related mainly to kinetic energy functional derivatives. They are able to reveal the shell
Doets, Hendrik Cornelis
2009-01-01
Ankle arthritis often leads to significant impairments for the patient. As total ankle arthroplasty (TAA) with use of fixed-bearing (2-component) total ankle prostheses has a high rate of early failures, fusion of the ankle joint is, until today, considered to be the standard surgical treatment for
Quantum corrections to nonlinear ion acoustic wave with Landau damping
Energy Technology Data Exchange (ETDEWEB)
Mukherjee, Abhik; Janaki, M. S. [Saha Institute of Nuclear Physics, Calcutta (India); Bose, Anirban [Serampore College, West Bengal (India)
2014-07-15
Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to the presence of Landau damping terms has been calculated assuming the Landau damping parameter α{sub 1}=√(m{sub e}/m{sub i}) to be of the same order of the quantum parameter Q=ℏ{sup 2}/(24m{sup 2}c{sub s}{sup 2}L{sup 2}). The amplitude is shown to decay very slowly with time as determined by the quantum factor Q.
Arya, Ved Bhushan; Senniappan, Senthil; Demirbilek, Huseyin; Alam, Syeda; Flanagan, Sarah E; Ellard, Sian; Hussain, Khalid
2014-01-01
Congenital hyperinsulinism (CHI), the commonest cause of persistent hypoglycaemia, has two main histological subtypes: diffuse and focal. Diffuse CHI, if medically unresponsive, is managed with near-total pancreatectomy. Post-pancreatectomy, in addition to persistent hypoglycaemia, there is a very high risk of diabetes mellitus and pancreatic exocrine insufficiency. International referral centre for the management of CHI. Medically unresponsive diffuse CHI patients managed with near-total pancreatectomy between 1994 and 2012. Near-total pancreatectomy. Persistent hypoglycaemia post near-total pancreatectomy, insulin-dependent diabetes mellitus, clinical and biochemical (faecal elastase 1) pancreatic exocrine insufficiency. Of more than 300 patients with CHI managed during this time period, 45 children had medically unresponsive diffuse disease and were managed with near-total pancreatectomy. After near-total pancreatectomy, 60% of children had persistent hypoglycaemia requiring medical interventions. The incidence of insulin dependent diabetes mellitus was 96% at 11 years after surgery. Thirty-two patients (72%) had biochemical evidence of severe pancreatic exocrine insufficiency (Faecal elastase 1insufficiency was observed in 22 (49%) patients. No statistically significant difference in weight and height standard deviation score (SDS) was found between untreated subclinical pancreatic exocrine insufficiency patients and treated clinical pancreatic exocrine insufficiency patients. The outcome of diffuse CHI patients after near-total pancreatectomy is very unsatisfactory. The incidence of persistent hypoglycaemia and insulin-dependent diabetes mellitus is very high. The presence of clinical rather than biochemical pancreatic exocrine insufficiency should inform decisions about pancreatic enzyme supplementation.
Virtual Routing Function Allocation Method for Minimizing Total Network Power Consumption
Kenichiro Hida; Shin-Ichi Kuribayashi
2016-01-01
In a conventional network, most network devices, such as routers, are dedicated devices that do not have much variation in capacity. In recent years, a new concept of network functions virtualisation (NFV) has come into use. The intention is to implement a variety of network functions with software on general-purpose servers and this allows the network operator to select their capacities and locations without any constraints. This paper focuses on the allocation of NFV-based routing functions...
Evaluation of radiation damping using 3-D finite element models
International Nuclear Information System (INIS)
Vaughan, D.K.; Isenberg, J.
1983-01-01
The paper presents an analytic approach which is being used to quantify the contribution of radiation damping to overall system damping. The approach uses three-dimensional finite element techniques and can easily include details of site geology, foundation shape, and embedment depth. The approach involves performing free vibration response analyses for each soil-structure interaction (SSI) mode of interest. The structural model is specified without damping and, consequently, amplitude decay of the structure's free vibration response is a measure of the radiation damping characteristics of the soil-structure system for the particular deformational mode being investigated. The computational approach developed is highly efficient in order to minimize the impact of including three-dimensional geometry within the model. A new finite element code, FLEX, has been developed to represent the soil continuum. FLEX uses a highly optimized explicit time integration algorithm which takes advantage of parallel processing on vector machines, such as the CRAY 1 computer. A modal representation of the superstructure is used in combination with a substructuring approach to solve for the coupled response of the soil-structure system. This requires solving for numerical Green's functions for each degree-of-freedom of the foundation (assumed rigid). Once computed for a particular site and foundation, these Green's functions may be used within a convolution integral to represent the continuum forces on the foundation for any free vibration SSI response computation of any superstructure model. This analytic approach is applied to an investigation of the radiation damping coefficients for the first two fundamental SSI modes of the HDR containment structure. (orig./HP)
The ROSETTA PHILAE Lander damping mechanism as probe for the Comet soil strength.
Roll, R.
2015-10-01
The ROSETTA Lander is equipped with an one axis damping mechanism to dissipate kinetic energy during the touch down. This damping is necessary to avoid damages to the Lander by a hard landing shock and more important to avoid re-bouncing from ground with high velocity. The damping mechanism works best for perpendicular impact, which means the velocity vector is parallel to the damper axis and all three feet touch the ground at the same time. That is usually not the case. Part of the impact energy can be transferred into rotational energy at ground contact if the impact is not perpendicular. This energy will lift up the Lander from the ground if the harpoons and the hold down thruster fail, as happen in mission. The damping mechanism itself is an electrical generator, driven by a spindle inside a telescopic tube. This tube was extended in mission for landing by 200mm. A maximum damping length of 140mm would be usually required to compensate a landing velocity of 1m/s, if the impact happens perpendicular on hard ground. After landing the potentiometer of the telescopic tube reading shows a total damping length of only 42,5mm. The damping mechanism and the overall mechanical behavior of the Lander at touch down are well tested and characterized and transferred to a multi-body computer model. The incoming and outgoing flightpath of PHILAE allow via computer-simulation the reconstruction of the touch down. It turns out, that the outgoing flight direction is dominated by the local ground slope and that the damping length is strongly dependent on the soil strength. Damping of soft comet ground must be included to fit the damping length measured. Scenario variations of the various feet contact with different local surface features (stone or regolith) and of different soil models finally lead to a restricted range for the soil strength at the touch down area.
Arya, Ved Bhushan; Senniappan, Senthil; Demirbilek, Huseyin; Alam, Syeda; Flanagan, Sarah E.; Ellard, Sian; Hussain, Khalid
2014-01-01
Context Congenital hyperinsulinism (CHI), the commonest cause of persistent hypoglycaemia, has two main histological subtypes: diffuse and focal. Diffuse CHI, if medically unresponsive, is managed with near-total pancreatectomy. Post-pancreatectomy, in addition to persistent hypoglycaemia, there is a very high risk of diabetes mellitus and pancreatic exocrine insufficiency. Setting International referral centre for the management of CHI. Patients Medically unresponsive diffuse CHI patients managed with near-total pancreatectomy between 1994 and 2012. Intervention Near-total pancreatectomy. Main Outcome Measures Persistent hypoglycaemia post near-total pancreatectomy, insulin-dependent diabetes mellitus, clinical and biochemical (faecal elastase 1) pancreatic exocrine insufficiency. Results Of more than 300 patients with CHI managed during this time period, 45 children had medically unresponsive diffuse disease and were managed with near-total pancreatectomy. After near-total pancreatectomy, 60% of children had persistent hypoglycaemia requiring medical interventions. The incidence of insulin dependent diabetes mellitus was 96% at 11 years after surgery. Thirty-two patients (72%) had biochemical evidence of severe pancreatic exocrine insufficiency (Faecal elastase 1pancreatectomy is very unsatisfactory. The incidence of persistent hypoglycaemia and insulin-dependent diabetes mellitus is very high. The presence of clinical rather than biochemical pancreatic exocrine insufficiency should inform decisions about pancreatic enzyme supplementation. PMID:24840042
Locked magnetic island chains in toroidally flow damped tokamak plasmas
International Nuclear Information System (INIS)
Fitzpatrick, R; Waelbroeck, F L
2010-01-01
The physics of a locked magnetic island chain maintained in the pedestal of an H-mode tokamak plasma by a static, externally generated, multi-harmonic, helical magnetic perturbation is investigated. The non-resonant harmonics of the external perturbation are assumed to give rise to significant toroidal flow damping in the pedestal, in addition to the naturally occurring poloidal flow damping. Furthermore, the flow damping is assumed to be sufficiently strong to relax the pedestal ion toroidal and poloidal fluid velocities to fixed values determined by neoclassical theory. The resulting neoclassical ion flow causes a helical phase-shift to develop between the locked island chain and the resonant harmonic of the external perturbation. Furthermore, when this phase-shift exceeds a critical value, the chain unlocks from the resonant harmonic and starts to rotate, after which it decays away and is replaced by a helical current sheet. The neoclassical flow also generates an ion polarization current in the vicinity of the island chain which either increases or decreases the chain's radial width, depending on the direction of the flow. If the polarization effect is stabilizing, and exceeds a critical amplitude, then the helical island equilibrium becomes unstable, and the chain again decays away. The critical amplitude of the resonant harmonic of the external perturbation at which the island chain either unlocks or becomes unstable is calculated as a function of the pedestal ion pressure, the neoclassical poloidal and toroidal ion velocities and the poloidal and toroidal flow damping rates.
Quantitative analysis of the thermal damping of coherent axion oscillations
International Nuclear Information System (INIS)
Turner, M.S.
1985-01-01
Unruh and Wald have recently discussed a new mechanism for damping coherent axion oscillations, ''thermal damping,'' which occurs due to the temperature dependence of the axion mass and neutrino viscosity. We investigate the effect quantitatively and find that the present energy density in axions can be written as rho/sub a/ = rho/sub a0//(1+J/sub UW/), where rho/sub a/0 is what the axion energy density would be in the absence of the thermal-damping effect and J/sub UW/ is an integral whose integrand depends upon (dm/sub a//dT) 2 . As a function of f(equivalentPeccei-Quinn symmetry-breaking scale) J/sub UW/ achieves its maximum value for f/sub PQ/approx. =3 x 10 12 GeV; unless the axion mass turn-on is very sudden, Vertical Bar(T/m/sub a/)(dm/sub a//dT)Vertical Bar>>1, J/sub UW/ is <<1, implying that this damping mechanism is not significant
Damping-off in forest nurseries
Carl Hartley
1921-01-01
Damping-off is the commonest English name for a symptomatic group of diseases affecting great numbers of plant species of widely separated phylogenetic groups. It is commonly used for any disease which results in the rapid decay of young succulent seedlings or soft cuttings. Young shoots from underground rootstocks may also be damped-off before they break through the...
Beam dynamic issues in TESLA damping ring
International Nuclear Information System (INIS)
Shiltsev, V.
1996-05-01
In this paper we study general requirements on impedances of the linear collider TESLA damping ring design. Quantitative consideration is performed for 17-km long ''dog-bone'' ring. Beam dynamics in alternative options of 6.3 and 2.3-km long damping rings is briefly discussed. 5 refs., 2 tabs
Study for ILC Damping Ring at KEKB
Energy Technology Data Exchange (ETDEWEB)
Flanagan, J.W.; Fukuma, H.; Kanazawa, K.I.; Koiso, H.; Masuzawa, M.; Ohmi, Kazuhito; Ohnishi, Y.; Oide, Katsunobu; Suetsugu, Y.; Tobiyama, M.; /KEK, Tsukuba; Pivi, M.; /SLAC
2011-11-04
ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.
Directory of Open Access Journals (Sweden)
Ved Bhushan Arya
Full Text Available Congenital hyperinsulinism (CHI, the commonest cause of persistent hypoglycaemia, has two main histological subtypes: diffuse and focal. Diffuse CHI, if medically unresponsive, is managed with near-total pancreatectomy. Post-pancreatectomy, in addition to persistent hypoglycaemia, there is a very high risk of diabetes mellitus and pancreatic exocrine insufficiency.International referral centre for the management of CHI.Medically unresponsive diffuse CHI patients managed with near-total pancreatectomy between 1994 and 2012.Near-total pancreatectomy.Persistent hypoglycaemia post near-total pancreatectomy, insulin-dependent diabetes mellitus, clinical and biochemical (faecal elastase 1 pancreatic exocrine insufficiency.Of more than 300 patients with CHI managed during this time period, 45 children had medically unresponsive diffuse disease and were managed with near-total pancreatectomy. After near-total pancreatectomy, 60% of children had persistent hypoglycaemia requiring medical interventions. The incidence of insulin dependent diabetes mellitus was 96% at 11 years after surgery. Thirty-two patients (72% had biochemical evidence of severe pancreatic exocrine insufficiency (Faecal elastase 1<100 µg/g. Clinical exocrine insufficiency was observed in 22 (49% patients. No statistically significant difference in weight and height standard deviation score (SDS was found between untreated subclinical pancreatic exocrine insufficiency patients and treated clinical pancreatic exocrine insufficiency patients.The outcome of diffuse CHI patients after near-total pancreatectomy is very unsatisfactory. The incidence of persistent hypoglycaemia and insulin-dependent diabetes mellitus is very high. The presence of clinical rather than biochemical pancreatic exocrine insufficiency should inform decisions about pancreatic enzyme supplementation.
Identification of Damping from Structural Vibrations
DEFF Research Database (Denmark)
Bajric, Anela
Reliable predictions of the dynamic loads and the lifetime of structures are inﬂuenced by the limited accuracy concerning the level of structural damping. The mechanisms of damping cannot be derived analytically from ﬁrst principles, and in the design of structures the damping is therefore based...... on experience or estimated from measurements. This thesis consists of an extended summary and three papers which focus on enhanced methods for identiﬁcation of damping from random struc-tural vibrations. The developed methods are validated by stochastic simulations, experimental data and full-scale measurements...... which are representative of the vibrations in small and large-scale structures. The ﬁrst part of the thesis presents an automated procedure which is suitable for estimation of the natural frequencies and the modal damping ratios from random response of structures. The method can be incorporated within...
Swing damped movement of suspended objects
International Nuclear Information System (INIS)
Jones, J.F.; Petterson, B.J.; Werner, J.C.
1990-01-01
Transportation of large objects such as nuclear waste shipping casks using overhead cranes can induce pendular motion of the object. Residual oscillation from transportation typically must be damped or allowed to decay before the next process can take place. By properly programming the acceleration of the transporting device (e.g., crane) an oscillation damped transport and swing free stop are obtainable. This report reviews the theory associated with formulating such oscillation damped trajectories for a simply suspended object (e.g., simple pendulum). In addition, the use of force servo damping to eliminate initial oscillation of simply suspended objects is discussed. This is often needed to provide a well defined initial state for the system prior to executing an oscillation damped move. Also included are descriptions of experiments using a CIMCORP XR6100 gantry robot and results from these experiments. Finally, sources of error resulting in small residual oscillations are identified and possible solutions presented
International Nuclear Information System (INIS)
Meyers, A.; Chachati, A.; Godon, J.P.; Rigo, P.
1985-01-01
The determination of renal uptake of 99m Tc DTPA and of 131 I Hippuran (as a percentage of the administred dose) at a time interval 1-3 minutes after tracer injection, is a rapid, accurate method for the measurement of total renal function and each kidney functions. Its clinical validity has been confirmed [fr
International Nuclear Information System (INIS)
Zheng Qi-Wen; Cui Jiang-Wei; Zhou Hang; Yu De-Zhao; Yu Xue-Feng; Lu Wu; Guo Qi; Ren Di-Yuan
2015-01-01
Functional failure mode of commercial deep sub-micron static random access memory (SRAM) induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize the functional failure mode of the device by testing its electrical parameters and function with test patterns covering different functional failure modes. Experimental results reveal that the functional failure mode of the device is a temporary function interruption caused by peripheral circuits being sensitive to the standby current rising. By including radiation-induced threshold shift and off-state leakage current in memory cell transistors, we simulate the influence of radiation on the functionality of the memory cell. Simulation results reveal that the memory cell is tolerant to irradiation due to its high stability, which agrees with our experimental result. (paper)
A PSO based unified power flow controller for damping of power system oscillations
Energy Technology Data Exchange (ETDEWEB)
Shayeghi, H. [Technical Engineering Dept., Univ. of Mohaghegh Ardabili, Daneshgah Street, P.O. Box 179, Ardabil (Iran); Shayanfar, H.A. [Center of Excellence for Power Automation and Operation, Electrical Engineering Dept., Iran Univ. of Science and Technology, Tehran (Iran); Jalilzadeh, S.; Safari, A. [Technical Engineering Dept., Zanjan Univ., Zanjan (Iran)
2009-10-15
On the basis of the linearized Phillips-Herffron model of a single-machine power system, we approach the problem of select the best input control signal of the unified power flow controller (UPFC) and design optimal UPFC based damping controller in order to enhance the damping of the power system low frequency oscillations. The potential of the UPFC supplementary controllers to enhance the dynamic stability is evaluated. This controller is tuned to simultaneously shift the undamped electromechanical modes to a prescribed zone in the s-plane. The problem of robustly UPFC based damping controller is formulated as an optimization problem according to the eigenvalue-based multiobjective function comprising the damping factor, and the damping ratio of the undamped electromechanical modes to be solved using particle swarm optimization technique (PSO) that has a strong ability to find the most optimistic results. To ensure the robustness of the proposed damping controller, the design process takes into account a wide range of operating conditions and system configurations. The effectiveness of the proposed controller is demonstrated through eigenvalue analysis, nonlinear time-domain simulation and some performance indices studies. The results analysis reveals that the tuned PSO based UPFC controller using the proposed multiobjective function has an excellent capability in damping power system low frequency oscillations and enhance greatly the dynamic stability of the power systems. Moreover, the system performance analysis under different operating conditions show that the {delta}{sub E} based controller is superior to the m{sub B} based controller. (author)
Directory of Open Access Journals (Sweden)
Nikolay M. Bogoliubov
2009-04-01
Full Text Available The basic model of the non-equilibrium low dimensional physics the so-called totally asymmetric exclusion process is related to the 'crystalline limit' (q → ∞ of the SU_q(2 quantum algebra. Using the quantum inverse scattering method we obtain the exact expression for the time-dependent stationary correlation function of the totally asymmetric simple exclusion process on a one dimensional lattice with the periodic boundary conditions.
Totally Optimal Decision Trees for Monotone Boolean Functions with at Most Five Variables
Chikalov, Igor; Hussain, Shahid; Moshkov, Mikhail
2013-01-01
In this paper, we present the empirical results for relationships between time (depth) and space (number of nodes) complexity of decision trees computing monotone Boolean functions, with at most five variables. We use Dagger (a tool for optimization
Directory of Open Access Journals (Sweden)
Yavuz Saglam
2016-08-01
Conclusion: Revision incidence was similar in between ankylosed and non-ankylosed hips. While complication rates are high, significant functional improvement can be achieved after THA in patients with AS.
DEFF Research Database (Denmark)
de Knegt, Martina Chantal; Biering-Sørensen, Tor; Søgaard, Peter
2016-01-01
BACKGROUND: The current method for a non-invasive assessment of diastolic dysfunction is complex with the use of algorithms of many different echocardiographic parameters. Total average diastolic longitudinal displacement (LD), determined by colour tissue Doppler imaging (TDI) via the measurement...
Landau damping effects on collision-induced quantum interference in electron-hole plasmas
International Nuclear Information System (INIS)
Hwa-Min, Kim; Young-Dae, Jung
2007-01-01
The Landau damping effects on the quantum interference in electron collisions are investigated in a quantum plasma composed of electrons and holes. The Born method and the total spin states are considered to obtain the scattering cross-section by using the effective screened potential model. It is found that the Landau damping effects enhance the scattering cross-section, especially, near the scattering angle θ L = π/4. (authors)
Landau damping effects on collision-induced quantum interference in electron-hole plasmas
Energy Technology Data Exchange (ETDEWEB)
Hwa-Min, Kim [Daegu Univ. Catholic, Dept. of Electronics Engineering (Korea, Republic of); Young-Dae, Jung [Hanyang Univ., Dept. of Applied Physics, Seoul (Korea, Republic of)
2007-07-15
The Landau damping effects on the quantum interference in electron collisions are investigated in a quantum plasma composed of electrons and holes. The Born method and the total spin states are considered to obtain the scattering cross-section by using the effective screened potential model. It is found that the Landau damping effects enhance the scattering cross-section, especially, near the scattering angle {theta}{sub L} = {pi}/4. (authors)
Radiation damping and decoherence in quantum electrodynamics
International Nuclear Information System (INIS)
Breuer, H.P.
2000-01-01
The processes of radiation damping and decoherence in quantum electrodynamics are studied from an open system's point of view. Employing functional techniques of field theory, the degrees of freedom of the radiation field are eliminated to obtain the influence phase functional which describes the reduced dynamics of the matter variables. The general theory is applied to the dynamics of a single electron in the radiation field. From a study of the wave packet dynamics a quantitative measure for the degree of decoherence, the decoherence function, is deduced. The latter is shown to describe the emergence of decoherence through the emission of bremsstrahlung caused by the relative motion of interfering wave packets. It is argued that this mechanism is the most fundamental process in quantum electrodynamics leading to the destruction of coherence, since it dominates for short times and because it is at work even in the electromagnetic field vacuum at zero temperature. It turns out that decoherence trough bremsstrahlung is very small for single electrons but extremely large for superpositions of many-particle states. (orig.)
Non-stationary pre-envelope covariances of non-classically damped systems
Muscolino, G.
1991-08-01
A new formulation is given to evaluate the stationary and non-stationary response of linear non-classically damped systems subjected to multi-correlated non-separable Gaussian input processes. This formulation is based on a new and more suitable definition of the impulse response function matrix for such systems. It is shown that, when using this definition, the stochastic response of non-classically damped systems involves the evaluation of quantities similar to those of classically damped ones. Furthermore, considerations about non-stationary cross-covariances, spectral moments and pre-envelope cross-covariances are presented for a monocorrelated input process.
Digital Realization of Capacitor-Voltage Feedback Active Damping for LCL-Filtered Grid Converters
DEFF Research Database (Denmark)
Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang
2015-01-01
The capacitor voltage of an LCL-filter can also be used for active damping, if it is fed back for synchronization. By this way, an extra current sensor can be avoided. Compared with the existing active damping techniques designed with capacitor current feedback, the capacitor voltage feedback....... To overcome their drawbacks, a new derivative method is then proposed, based on the non-ideal generalized integrator. The performance of the proposed derivative has been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately...
Highly Accurate Derivatives for LCL-Filtered Grid Converter with Capacitor Voltage Active Damping
DEFF Research Database (Denmark)
Xin, Zhen; Loh, Poh Chiang; Wang, Xiongfei
2016-01-01
The middle capacitor voltage of an LCL-filter, if fed back for synchronization, can be used for active damping. An extra sensor for measuring the capacitor current is then avoided. Relating the capacitor voltage to existing popular damping techniques designed with capacitor current feedback would...... are then proposed, based on either second-order or non-ideal generalized integrator. Performances of these derivatives have been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately. Experimental results presented have verified...
Total radiative width (Γγ) as a function of mass number A
International Nuclear Information System (INIS)
Huynh, V.D.; Barros, S. De; Chevillon, P.L.; Julien, J.; Poittevin, G. Le; Morgenstern, J.; Samour, C.
1967-01-01
The total radiative width Γ γ was measured accurately for a large number of nuclei. These values, which are important for reactor calculations, are difficult to determine. The fluctuations in Γ γ from resonance to resonance in the same nucleus are discussed in terms of level parity and the de-excitation scheme. The authors compare the experimental values with those predicted by theory. (author) [fr
De Caro, M F; Vicenti, G; Abate, A; Picca, G; Leoncini, V; Lomuscio, M; Casalino, A; Solarino, G; Moretti, B
2015-01-01
Osteoarthritis (OA) of the hip and knee causes pain and loss of joint mobility, leading to limitations in physical function. When conservative treatment fails total hip and knee replacement is a cost-effective surgical option. Patients have high expectations regarding functional outcome after these procedures. If such expectations are not met, they may still be dissatisfied with the outcome of a technically successful procedure. Recently, numerous studies reported that psychological factors can influence the outcome of total knee replacement (tkr) and total hip artrhoplasty with total hip replacement (thr). We conducted a prospective study on a consecutive sample of 280 patients affected by hip or knee OA who underwent total joint replacement. At patients admission, Harris Hip Score (HHS) and Knee Society Score (KSS) were used to assess pain and function. Furthermore, SF-36, Mini-Mental Status Examination (MMSE), Symptom Checklist-90-R (SCL-90-R), Coping Orientation to Problems Experienced (BRIEF-COPE) and the Amsterdam Preoperative Anxiety and Information Scale (APAIS) were administered. Patients had clinical and radio graphical follow up at 1, 3 and 6 months post-operatively. The HHS and KSS values before surgery showed a linear correlation with both SCL-90-R and MMSE. None of the investigated variables influenced post-operative HHS and KSS scores; however, the improvement of functional scores resulted conditioned by SCL-90-R values, VAS score, schooling and MMSE. Psychological factors and mental status in primary total hip and knee replacement can affect outcome and patient satisfaction. Strategies focused on identification and facing of these conditions must be considered to improve outcome of total replacement.
Directory of Open Access Journals (Sweden)
Bin Zhao
2014-05-01
Full Text Available This study presents the auxiliary damping control with the reactive power loop on the rotor-side converter of doubly-fed induction generator (DFIG-based wind farms to depress the sub-synchronous resonance oscillations in nearby turbogenerators. These generators are connected to a series capacitive compensation transmission system. First, the damping effect of the reactive power control of the DFIG-based wind farms was theoretically analyzed, and a transfer function between turbogenerator speed and the output reactive power of the wind farms was introduced to derive the analytical expression of the damping coefficient. The phase range to obtain positive damping was determined. Second, the PID phase compensation parameters of the auxiliary damping controller were optimized by a genetic algorithm to obtain the optimum damping in the entire subsynchronous frequency band. Finally, the validity and effectiveness of the proposed auxiliary damping control were demonstrated on a modified version of the IEEE first benchmark model by time domain simulation analysis with the use of DigSILENT/PowerFactory. Theoretical analysis and simulation results show that this derived damping factor expression and the condition of the positive damping can effectively analyze their impact on the system sub-synchronous oscillations, the proposed wind farms reactive power additional damping control strategy can provide the optimal damping effect over the whole sub-synchronous frequency band, and the control effect is better than the active power additional damping control strategy based on the power system stabilizator.
Electric Generator in the System for Damping Oscillations of Vehicles
Serebryakov A.; Kamolins E.; Levin N.
2017-01-01
The control systems for the objects of industry, power generation, transport, etc. are extremely complicated; functional efficiency of these systems determines to a great extent the safe and non-polluting operation as well as convenience of service and repair of such objects. The authors consider the possibility to improve the efficiency of systems for damping oscillations in transport using a combination of electrical (generators of rotational and linear types) and hydraulic means. Better ef...
National Research Council Canada - National Science Library
Drummond, Sean P
2004-01-01
.... Even less is known about the cerebral effects of recovery sleep. The overarching objective of this study is to investigate the effects of 2 full nights of sleep loss and 2 full nights of recovery sleep on cognitive performance and brain function...
National Research Council Canada - National Science Library
Gillin, J
2003-01-01
..... Even less is known about the cerebral effects of recovery sleep. The objective of this study is to investigate the effects of 2 full nights of sleep loss and 2 full nights of recovery sleep on cognitive performance and brain function...
Towards Total Quality Management in Universities: Quality Function Deployment Paradigm and Beyond
Al-Fuqaha, Isam Najib
2014-01-01
This paper is an endeavor to develop a customised and computerized matrix of Quality Function Deployment paradigm (QFD) that has been applied in industry, with the aim of probing quality assurance and enhancement in Universities. Results of testing the new matrix proved that, it is efficient and time-saving while compared with a detailed field…
Shape memory alloys as damping materials
International Nuclear Information System (INIS)
Humbeeck, J. van
2000-01-01
Shape memory alloys are gaining an increased interest as passive as well as active damping materials. This damping ability when applied in structural elements can lead to a better noise control, improved life time and even better performance of the envisaged tools. By passive damping, it is understood that the material converts a significant part of unwanted mechanical energy into heat. This mechanical energy can be a (resonance) vibration, impact loading or shock waves. This high damping capacity finds its origin in the thermoelastic martensitic phase due to the hysteretic mobility of martensite-variants or different phase interfaces. The damping capacity increases with increasing amplitude of the applied vibration or impact and is almost frequency independent. Special interest exists moreover for damping extreme large displacements by applying the mechanical hysteresis performed during pseudoelastic loading. This aspect is nowadays very strongly studied as a tool for protecting buildings against earthquakes in seismic active regions. Active damping can be obtained in hybrid composites by controlling the recovery stresses or strains of embedded shape memory alloy wires. This controls the internal energy fo a structure which allows controlled modal modification and tuning of the dynamical properties of structural elements. But also impact damage, acoustic radiation, dynamic shape control can be actively controlled. As a consequence improved fatigue-resistance, better performance and a longer lifetime of the structural elements can be obtained. (orig.)
LENUS (Irish Health Repository)
Walls, Raymond J
2010-01-01
Supervised preoperative muscle strengthening programmes (prehabilitation) can improve recovery after total joint arthroplasty but are considered resource intensive. Neuromuscular electrical stimulation (NMES) has been shown to improve quadriceps femoris muscle (QFM) strength and clinical function in subjects with knee osteoarthritis (OA) however it has not been previously investigated as a prehabilitation modality.
DEFF Research Database (Denmark)
Huber, Erika O; Roos, Ewa M.; Meichtry, André
2015-01-01
baseline to 3 months after Total Knee Replacement (TKR) following a neuromuscular exercise programme (NEMEX-TJR) plus a knee school educational package (KS) or KS alone. METHODS: 45 patients (55-83 years, 53% male, waiting for TKR) were randomized to receive a minimum of 8 sessions of NEMEXTJR plus 3...... and after the intervention, and at 6 weeks, 3 months and 12 months after surgery by a physiotherapist, blinded to group allocation. RESULTS: After intervention before surgery we observed a small improvement for primary and secondary endpoints in both groups, which did not differ significantly between groups...
Bunch lengthening in the SLC [Stanford Linear Collider] damping rings
International Nuclear Information System (INIS)
Bane, K.L.F.
1990-02-01
A high level of current dependent bunch lengthening has been observed on the North damping ring of the Stanford Linear Collider (SLC). At currents of 3 x 10 10 this behavior does not appear to degrade the machine's performance significantly. However, at the higher currents that are envisioned for the future one fears that its performance could be greatly degraded due to the phenomenon of bunch lengthening. This was the motivation for the work described in this paper. In this paper we calculate the longitudinal impedance of the damping ring vacuum chamber. More specifically, in this paper we find the response function of the ring to a short Gaussian bunch, which we call the Green function wake. In addition, we try to estimate the relative importance of the different vacuum chamber objects, in order to see how we might reduce the ring impedance. This paper also describes bunch length measurements performed on the North damping ring. We use the Green function wake, discussed above, to compute the bunch lengthening. Then we compare these results with those obtained from the measurements. In addition, we calculate the current dependence of the tune distribution
Dispersion relation and Landau damping of waves in high-energy density plasmas
International Nuclear Information System (INIS)
Zhu Jun; Ji Peiyong
2012-01-01
We present a theoretical investigation on the propagation of electromagnetic waves and electron plasma waves in high energy density plasmas using the covariant Wigner function approach. Based on the covariant Wigner function and Dirac equation, a relativistic quantum kinetic model is established to describe the physical processes in high-energy density plasmas. With the zero-temperature Fermi–Dirac distribution, the dispersion relation and Landau damping of waves containing the relativistic quantum corrected terms are derived. The relativistic quantum corrections to the dispersion relation and Landau damping are analyzed by comparing our results with those obtained in classical and non-relativistic quantum plasmas. We provide a detailed discussion on the Landau damping obtained in classical plasmas, non-relativistic Fermi plasmas and relativistic Fermi plasmas. The contributions of the Bohm potential, the Fermi statistics pressure and relativistic effects to the dispersion relation and Landau damping of waves are quantitatively calculated with real plasma parameters. (paper)
Passive secondary magnetic damping for superconducting Maglev vehicles
International Nuclear Information System (INIS)
Atherton, D.L.; Eastham, A.R.; Sturgess, K.
1976-01-01
We analyze a passive magnetic damping scheme for the secondary suspension of a superconducting Maglev vehicle. The unsprung levitation or linear synchronous motor magnets are coupled electromagnetically to short-circuited aluminum damper coils mounted on the underside of the sprung mass. Relative motion between the magnets and the passenger compartment causes a time-dependent flux linkage which induces dissipative currents in the coils. Analysis for the typical Canadian Maglev vehicle design shows that a damping factor of 1 sec/sup -1/ can be obtained with a total coil mass of approximately 100 kg, for a secondary/primary suspension stiffness ratio of 0.2. This scheme appears to offer a design alternative to conventional frictional or hydraulic dampers
Can computer assistance improve the clinical and functional scores in total knee arthroplasty?
Hernández-Vaquero, Daniel; Suarez-Vazquez, Abelardo; Iglesias-Fernandez, Susana
2011-12-01
Surgical navigation in TKA facilitates better alignment; however, it is unclear whether improved alignment alters clinical evolution and midterm and long-term complication rates. We determined the alignment differences between patients with standard, manual, jig-based TKAs and patients with navigation-based TKAs, and whether any differences would modify function, implant survival, and/or complications. We retrospectively reviewed 97 patients (100 TKAs) undergoing TKAs for minimal preoperative deformities. Fifty TKAs were performed with an image-free surgical navigation system and the other 50 with a standard technique. We compared femoral angle (FA), tibial angle (TA), and femorotibial angle (FTA) and determined whether any differences altered clinical or functional scores, as measured by the Knee Society Score (KSS), or complications. Seventy-three patients (75 TKAs) had a minimum followup of 8 years (mean, 8.3 years; range, 8-9.1 years). All patients included in the surgical navigation group had a FTA between 177° and 182º. We found no differences in the KSS or implant survival between the two groups and no differences in complication rates, although more complications occurred in the standard technique group (seven compared with two in the surgical navigation group). In the midterm, we found no difference in functional and clinical scores or implant survival between TKAs performed with and without the assistance of a navigation system. Level II, therapeutic study. See the Guidelines online for a complete description of levels of evidence.
Lifetime measurement of ATF damping ring
International Nuclear Information System (INIS)
Okugi, T.; Hayano, H.; Kubo, K.; Naito, T.; Terunuma, N.; Urakawa, J.; Zimmermann, F.
1998-06-01
The purpose of the ATF damping ring is the development of technologies for producing a low emittance beam required in future linear colliders such as JLC. The lifetime of the damping ring is very short (typically a few minutes). It is limited by elastic beam-gas scattering along with a small dynamic aperture, and by single intra-beam scattering (Touschek effect). The Touschek lifetime strongly depends upon the charge density of the beam, especially, the size of the vertical emittance. In this paper, the authors report the results of beam lifetime measurements in the ATF damping ring and the estimation of the vertical emittance from these measurements
A Resonant Damping Study Using Piezoelectric Materials
Min, J. B.; Duffy, K. P.; Choi, B. B.; Morrison, C. R.; Jansen, R. H.; Provenza, A. J.
2008-01-01
Excessive vibration of turbomachinery blades causes high cycle fatigue (HCF) problems requiring damping treatments to mitigate vibration levels. Based on the technical challenges and requirements learned from previous turbomachinery blade research, a feasibility study of resonant damping control using shunted piezoelectric patches with passive and active control techniques has been conducted on cantilever beam specimens. Test results for the passive damping circuit show that the optimum resistive shunt circuit reduces the third bending resonant vibration by almost 50%, and the optimum inductive circuit reduces the vibration by 90%. In a separate test, active control reduced vibration by approximately 98%.
International Nuclear Information System (INIS)
Seeley, Charles; Coutu, André; Monette, Christine; Nennemann, Bernd; Marmont, Hugues
2012-01-01
Hydroelectric power generation is an important non-fossil fuel power source to help meet the world’s energy needs. Fluid–structure interaction (FSI), in the form of mass loading and damping, governs the dynamic response of water turbines, such as Francis turbines. Although the effects of fluid mass loading are well documented, fluid damping is also a critical quantity that may limit vibration amplitudes during service, and therefore help to avoid premature failure of the turbines. However, fluid damping has received less attention in the literature. This paper presents an experimental investigation of damping due to FSI. Three hydrofoils were designed and built to investigate damping due to FSI. Piezoelectric actuation using macrofiber composites (MFCs) provided excitation to the hydrofoil test structure, independent of the flow conditions, to overcome the noisy environment. Natural frequency and damping estimates were experimentally obtained from sine sweep frequency response functions measured with a laser vibrometer through a window in the test section. The results indicate that, although the natural frequencies were not substantially affected by the flow, the damping ratios were observed to increase in a linear manner with respect to flow velocity. (paper)
Seeley, Charles; Coutu, André; Monette, Christine; Nennemann, Bernd; Marmont, Hugues
2012-03-01
Hydroelectric power generation is an important non-fossil fuel power source to help meet the world’s energy needs. Fluid-structure interaction (FSI), in the form of mass loading and damping, governs the dynamic response of water turbines, such as Francis turbines. Although the effects of fluid mass loading are well documented, fluid damping is also a critical quantity that may limit vibration amplitudes during service, and therefore help to avoid premature failure of the turbines. However, fluid damping has received less attention in the literature. This paper presents an experimental investigation of damping due to FSI. Three hydrofoils were designed and built to investigate damping due to FSI. Piezoelectric actuation using macrofiber composites (MFCs) provided excitation to the hydrofoil test structure, independent of the flow conditions, to overcome the noisy environment. Natural frequency and damping estimates were experimentally obtained from sine sweep frequency response functions measured with a laser vibrometer through a window in the test section. The results indicate that, although the natural frequencies were not substantially affected by the flow, the damping ratios were observed to increase in a linear manner with respect to flow velocity.
On the experimental prediction of the stability threshold speed caused by rotating damping
Vervisch, B.; Derammelaere, S.; Stockman, K.; De Baets, P.; Loccufier, M.
2016-08-01
An ever increasing demand for lighter rotating machinery and higher operating speeds results in a raised probability of instabilities. Rotating damping is one of the reasons, instability occurs. Rotating damping, or rotor internal damping, is the damping related to all rotating parts while non-rotating damping appearing in the non-rotating parts. The present study describes a rotating setup, designed to investigate rotating damping experimentally. An efficient experimental procedure is presented to predict the stability threshold of a rotating machine. The setup consists of a long thin shaft with a disk in the middle and clamped boundary conditions. The goal is to extract the system poles as a function of the rotating speed. The real parts of these poles are used to construct the decay rate plot, which is an indication for the stability. The efficiency of the experimental procedure relies on the model chosen for the rotating shaft. It is shown that the shaft behavior can be approximated by a single degree of freedom model that incorporates a speed dependent damping. As such low measurement effort and only one randomly chosen measurement location are needed to construct the decay rate plot. As an excitation, an automated impact hammer is used and the response is measured by eddy current probes. The proposed method yields a reliable prediction of the stability threshold speed which is validated through measurements.
DEFF Research Database (Denmark)
Xu, Hui; Birgisson, Steinar; Sommer, Sanna
structure. At the same time, there is an ongoing debate on whether the SBU is present prior, or during MOF crystallization in MOF chemistry. However, little is known about MOFs formation mechanism. Currently techniques to study the in situ MOF formation process mainly focused on after......-crystallization process, for example in situ XRD and SAXS/WAXS study on MOF formation. However, the pre-crystallization process in the early stage of MOF formation is still unexplored. In this project, total scattering and PDF study will be carried out to explore the MOF formation process in early stage. This includes......Metal-Organic Frameworks (MOFs) is constructed by metal-oxide nodes and organic ligands. The formation of different structures of metal-oxide nodes (also called secondary building units, SBU) is crucial for MOF final structures, because the connectivity of SBU greatly influence the final MOF...
DEFF Research Database (Denmark)
de Knegt, Martina Chantal; Biering-Sørensen, Tor; Søgaard, Peter
2016-01-01
of LD during early diastole and atrial contraction, can potentially be used as a simple and reliable alternative. METHODS: In 206 patients, using GE Healthcare Vivid E7 and 9 and Echopac BT11 software, we determined both diastolic LD, measured in the septal and lateral walls in the apical 4-chamber view...... by TDI, and the degree of diastolic dysfunction, based on current guidelines. Of these 206 patients, 157 had cardiac anomalies that could potentially affect diastolic LD such as severe systolic heart failure (n = 45), LV hypertrophy (n = 49), left ventricular (LV) dilation (n = 30), and mitral...... for the general discrimination of patients with or without diastolic dysfunction. Using linear regression, total average diastolic LD was estimated to fall by 2.4 mm for every increase in graded severity of diastolic dysfunction (β = -0.61, p-value
Chromium 51 EDTA/technetium 99m MDP plasma ratio to measure total skeletal function
Energy Technology Data Exchange (ETDEWEB)
Nisbet, A.P.; Edwards, S.; Lazarus, C.R.; Malamitsi, J.; Maisey, M.N.; Mashiter, G.D.; Winn, P.J. (Guy' s Hospital, London (UK))
1984-08-01
A method is described for the quantitation of total skeletal activity during bone scans. The method requires a single plasma sample only, taken at the time of imaging. The ratio of % injected dose of /sup 51/Cr EDTA to that of /sup 99/Tcsup(m) MDP is calculated from this sample following combined injection of the two radiopharmaceuticals. The /sup 51/Cr EDTA level corrects for the glomerular filtration of /sup 99/Tcsup(m) MDP. Using this method, which only requires a gamma counter, significant differences from normal controls have been shown in patients with osteomalacia, renal osteodystrophy, Paget's disease and hypercalcaemia. The method provides routine quantitative data to add to the imaging information in the bone scan.
About the damping of quark-hadron form factors in relative quark momentum
International Nuclear Information System (INIS)
Lewin, K.; Kallies, W.
1979-01-01
A problem of sufficient damping of hadron bound states at nonasymptotic relative quark momenta is discussed. This phenomenon is considered in the connection with the power scaling beginning at momentum transfer | t | >= 2-3 GeV 2 . Damping of hadron bound states is obtained on the basis of a behaviour of four-quark Green's functions in the momentum transfer which is required by diffraction scattering
Directory of Open Access Journals (Sweden)
Liping Sun
2017-02-01
Full Text Available Thirteen popular wild edible mushroom species in Yunnan Province, Boletus bicolor, Boletus speciosus, Boletus sinicus, Boletus craspedius, Boletus griseus, Boletus ornatipes, Xerocomus, Suillus placidus, Boletinus pinetorus, Tricholoma terreum, Tricholomopsis lividipileata, Termitomyces microcarpus, and Amanita hemibapha, were analyzed for their free amino acid compositions by online pre-column derivazation reversed phase high-performance liquid chromatography (RP-HPLC analysis. Twenty free amino acids, aspartic acid, glutamic acid, serine, glycine, alanine, praline, cysteine, valine, methionine, phenylalanine, isoleucine, leucine, lysine, histidine, threonine, asparagines, glutamine, arginine, tyrosine, and tryptophan, were determined. The total free amino acid (TAA contents ranged from 1462.6 mg/100 g in B. craspedius to 13,106.2 mg/100 g in T. microcarpus. The different species showed distinct free amino acid profiles. The ratio of total essential amino acids (EAA to TAA was 0.13–0.41. All of the analyzed species showed high contents of hydrophobic amino acids, at 33%–54% of TAA. Alanine, cysteine, glutamine, and glutamic acid were among the most abundant amino acids present in all species. The results showed that the analyzed mushrooms possessed significant free amino acid contents, which may be important compounds contributing to the typical mushroom taste, nutritional value, and potent antioxidant properties of these wild edible mushrooms. Furthermore, the principal component analysis (PCA showed that the accumulative variance contribution rate of the first four principal components reached 94.39%. Cluster analysis revealed EAA composition and content might be an important parameter to separate the mushroom species, and T. microcarpus and A. hemibapha showed remarkable EAA content among the 13 species.
International Nuclear Information System (INIS)
Jung, Byung C.; Lee, Doo Ho; Youn, Byeng D.; Lee, Soo Bum
2011-01-01
The performance of surface damping treatments may vary once the surface is exposed to a wide range of temperatures, because the performance of viscoelastic damping material is highly dependent on operational temperature. In addition, experimental data for dynamic responses of viscoelastic material are inherently random, which makes it difficult to design a robust damping layout. In this paper a statistical modeling procedure with a statistical calibration method is suggested for the variability characterization of viscoelastic damping material in constrained-layer damping structures. First, the viscoelastic material property is decomposed into two sources: (I) a random complex modulus due to operational temperature variability, and (II) experimental/model errors in the complex modulus. Next, the variability in the damping material property is obtained using the statistical calibration method by solving an unconstrained optimization problem with a likelihood function metric. Two case studies are considered to show the influence of the material variability on the acoustic performances in the structural-acoustic systems. It is shown that the variability of the damping material is propagated to that of the acoustic performances in the systems. Finally, robust and reliable damping layout designs of the two case studies are obtained through the reliability-based design optimization (RBDO) amidst severe variability in operational temperature and the damping material
International Nuclear Information System (INIS)
Kim, Eun-San
2003-01-01
This paper shows the results of a numerical study of the impedance in the Accelerator Test Facility damping ring. The longitudinal impedance in the damping ring is shown to be inductive. It is shown that the total impedance |Z || /n| is 0.23 Ω and the inductance is L = 14 nH. In the extremely low emittance beam of the damping ring, bunch lengthening is caused by both the effects of potential-well distortion and intra-beam scattering. In this paper, the bunch-lengthening due to the ring impedance is numerically investigated, and the result shows qualitative agreement with the result of an analysis performed using the bunch-length measurement. With the calculated longitudinal impedance, the instability threshold in the damping ring is estimated to be a bunch population of 3.3 x 10 10 by using both a Vlasov equation approach and a multi-particle tracking method.
Moutzouri, Maria; Gleeson, Nigel; Coutts, Fiona; Tsepis, Elias; John, Gliatis
2018-02-01
To assess the effects of early self-managed focal sensorimotor training compared to functional exercise training after total knee replacement on functional mobility and sensorimotor function. A single-blind controlled clinical trial. University Hospital of Rion, Greece. A total of 52 participants following total knee replacement. The primary outcome was the Timed Up and Go Test and the secondary outcomes were balance, joint position error, the Knee Outcome Survey Activities of Daily Living Scale, and pain. Patients were assessed on three separate occasions (presurgery, 8 weeks post surgery, and 14 weeks post surgery). Participants were randomized to either focal sensorimotor exercise training (experimental group) or functional exercise training (control group). Both groups received a 12-week home-based programme prescribed for 3-5 sessions/week (35-45 minutes). Consistently greater improvements ( F 2,98 = 4.3 to 24.8; P effect size range of 1.3-6.5. Overall, the magnitude of improvements in functional mobility and sensorimotor function endorses using focal sensorimotor training as an effective mode of rehabilitation following knee replacement.
Similar range of motion and function after resurfacing large-head or standard total hip arthroplasty
DEFF Research Database (Denmark)
Penny, Jeannette Østergaard; Ovesen, Ole; Varmarken, Jens-Erik
2013-01-01
BACKGROUND AND PURPOSE: Large-size hip articulations may improve range of motion (ROM) and function compared to a 28-mm THA, and the low risk of dislocation allows the patients more activity postoperatively. On the other hand, the greater extent of surgery for resurfacing hip arthroplasty (RHA......° (35), 232° (36), and 225° (30) respectively, but the differences were not statistically significant. The 3 groups were similar regarding Harris hip score, UCLA activity score, step rate, and sick leave. INTERPRETATION: Head size had no influence on range of motion. The lack of restriction allowed...... for large articulations did not improve the clinical and patient-perceived outcomes. The more extensive surgical procedure of RHA did not impair the rehabilitation. This project is registered at ClinicalTrials.gov under # NCT01113762....
Directory of Open Access Journals (Sweden)
Renske Uiterwijk
2016-12-01
Full Text Available Objectives: Hypertension is a major risk factor for white matter hyperintensities, lacunes, cerebral microbleeds and perivascular spaces, which are MRI markers of cerebral small vessel disease (SVD. Studies have shown associations between these individual MRI markers and cognitive functioning and decline. Recently, a total SVD score was proposed in which the different MRI markers were combined into one measure of SVD, to capture total SVD-related brain damage. We investigated if this SVD score was associated with cognitive decline over 4 years in patients with hypertension. Methods: In this longitudinal cohort study, 130 hypertensive patients (91 patients with uncomplicated hypertension and 39 hypertensive patients with a lacunar stroke were included. They underwent a neuropsychological assessment at baseline and after 4 years. The presence of white matter hyperintensities, lacunes, cerebral microbleeds, and perivascular spaces were rated on baseline MRI. Presence of each individual marker was added to calculate the total SVD score (range 0-4 in each patient. Results: Uncorrected linear regression analyses showed associations between SVD score and decline in overall cognition (p=0.017, executive functioning (p<0.001 and information processing speed (p=0.037, but not with memory (p=0.911. The association between SVD score and decline in overall cognition and executive function remained significant after adjustment for age, sex, education, anxiety and depression score, potential vascular risk factors, patient group and baseline cognitive performance.Conclusions: Our study shows that a total SVD score can predict cognitive decline, specifically in executive function, over 4 years in hypertensive patients. This emphasizes the importance of considering total brain damage due to SVD.
Resonant Electromagnetic Shunt Damping of Flexible Structures
DEFF Research Database (Denmark)
Høgsberg, Jan Becker
2016-01-01
Electromagnetic transducers convert mechanical energy to electrical energy and vice versa. Effective passive vibration damping of flexible structures can therefore be introduced by shunting with an accurately calibrated resonant electrical network thatcontains a capacitor to create the desired...
Offline software for the DAMPE experiment
Wang, Chi; Liu, Dong; Wei, Yifeng; Zhang, Zhiyong; Zhang, Yunlong; Wang, Xiaolian; Xu, Zizong; Huang, Guangshun; Tykhonov, Andrii; Wu, Xin; Zang, Jingjing; Liu, Yang; Jiang, Wei; Wen, Sicheng; Wu, Jian; Chang, Jin
2017-10-01
A software system has been developed for the DArk Matter Particle Explorer (DAMPE) mission, a satellite-based experiment. The DAMPE software is mainly written in C++ and steered using a Python script. This article presents an overview of the DAMPE offline software, including the major architecture design and specific implementation for simulation, calibration and reconstruction. The whole system has been successfully applied to DAMPE data analysis. Some results obtained using the system, from simulation and beam test experiments, are presented. Supported by Chinese 973 Program (2010CB833002), the Strategic Priority Research Program on Space Science of the Chinese Academy of Science (CAS) (XDA04040202-4), the Joint Research Fund in Astronomy under cooperative agreement between the National Natural Science Foundation of China (NSFC) and CAS (U1531126) and 100 Talents Program of the Chinese Academy of Science
Electron beam depolarization in a damping ring
International Nuclear Information System (INIS)
Minty, M.
1993-04-01
Depolarization of a polarized electron beam injected into a damping ring is analyzed by extending calculations conventionally applied to proton synchrotrons. Synchrotron radiation in an electron ring gives rise to both polarizing and depolarizing effects. In a damping ring, the beam is stored for a time much less than the time for self polarization. Spin flip radiation may therefore be neglected. Synchrotron radiation without spin flips, however, must be considered as the resonance strength depends on the vertical betatron oscillation amplitude which changes as the electron beam is radiation damped. An expression for the beam polarization at extraction is derived which takes into account radiation damping. The results are applied to the electron ring at the Stanford Linear Collider and are compared with numerical matrix formalisms
Damping Wiggler Study at KEK-ATF
Naito, Takashi; Honda, Yosuke; Korostelev, Maxim S; Kubo, Kiyoshi; Kuriki, Masao; Kuroda, Shigeru; Muto, Toshiya; Nakamura, Norio; Ross, Marc; Sakai, Hiroshi; Terunuma, Nobuhiro; Urakawa, Junji; Zimmermann, Frank
2005-01-01
The effects by damping wiggler magnets have been studied at KEK-ATF. The damping ring of the KEK-ATF is a 1.3 GeV storage ring capable of producing ultra-low emittance electron beams. It is significant issue to realize fast damping in the damping ring. The tuning method with 4 sets of wiggler was investigated for the ultra-low emittance beam. The performance on the beam quality, which is related to the transverse (x and y) and the longitudinal (z and dp/p), has been measured by the SR monitor, the laser wire, the streak camera and the energy spread monitor at the extraction line. We report on the operation condition and the measurement results.
Damping of type III solar radio bursts
International Nuclear Information System (INIS)
Levin, B.N.
1982-01-01
The meter- and decameter-wavelength damping of type III bursts may be attributable to stabilization of the Langmuir-wave instability of the fast-electron streams through excitation of cyclotron-branch plasma waves
Resistive Wall Instability in the NLC Main Damping Rings
International Nuclear Information System (INIS)
Wolski, Andrzej
2004-01-01
We study transverse coupled-bunch instabilities driven by the resistive-wall impedance in the NLC Main Damping Rings. We compare the growth rates of the different modes predicted by a simple theory using a simplified lattice model with the results of a detailed simulation that includes variation of the beta functions and the actual fill structure of the machine. We find that the results of the analytical calculations are in reasonable agreement with the simulations. We include a simple model of a bunch-by-bunch feedback system in the simulation to show that the instabilities can be damped by a feedback system having parameters that are realistic, and possibly conservative. The noise level on the feedback system pick-up must be low, to avoid driving random bunch-to-bunch jitter above the specified limit of 10 percent of the vertical beam size
Collisional damping of giant monopole and quadrupole resonances
International Nuclear Information System (INIS)
Yildirim, S.; Gokalp, A.; Yilmaz, O.; Ayik, S.
2001-01-01
Collisional damping widths of giant monopole and quadrupole excitations for 120 Sn and 208 Pb at zero and finite temperatures are calculated within Thomas-Fermi approximation by employing the microscopic in-medium cross-sections of Li and Machleidt and the phenomenological Skyrme and Gogny forces, and are compared with each other. The results for the collisional widths of giant monopole and quadrupole vibrations at zero temperature as a function of the mass number show that the collisional damping of giant monopole vibrations accounts for about 30 - 40% of the observed widths at zero temperature, while for giant quadrupole vibrations it accounts for only 20 - 30% of the observed widths at zero temperature. (orig.)
Landau damping in bi-dust ion-acoustic waves
International Nuclear Information System (INIS)
Castro, E.; Puerta, J.; Martin, P.; Cereceda, C.
2006-01-01
Ion acoustic dust waves in a bi-dust plasma are analyzed in this paper. In order to model this system, we assume the existence of two different kinds of grains, each characterized by a different radius. Relative velocities between grains and charge fluctuations are neglected. In order to derive the dispersion relation of this system, we use the well known hybrid fluid-kinetic model, in which ions are treated kinetically and other species as fluids. In this plasma, waves with non-relative velocities between species leads to damped waves with frequency modes, defined by the grain radius. The induced damping ratio is studied as a function of the grain and ion densities. (Author)
Intrabeam Scattering in the NLC Main Damping Rings
International Nuclear Information System (INIS)
Wolski, Andrzej
2006-01-01
We use Bane's approximation to the Bjorken-Mtingwa theory of intrabeam scattering to calculate the emittance growth as a function of bunch charge in the KEK ATF. We find that our results are consistent with the experimental data. We then calculate the emittance growth in the NLC Main Damping Rings using the same formulae; we allow for some uncertainty in the ATF data by using two different values for the Coulomb log factor in the formulae for the emittance growth rates. We find that despite the IBS emittance growth, it should still be possible to achieve the specified transverse and longitudinal emittances in the NLC Main Damping Rings at the specified bunch charge
International Nuclear Information System (INIS)
Vancura, J.; Kostroun, V.O.
1992-01-01
The absolute total and one and two electron transfer cross sections for Ar 8+ on Ar were measured as a function of projectile laboratory energy from 0.090 to 0.550 keV/amu. The effective one electron transfer cross section dominates above 0.32 keV/amu, while below this energy, the effective two electron transfer starts to become appreciable. The total cross section varies by a factor over the energy range explored. The overall error in the cross section measurement is estimated to be ± 15%
Proceedings of Damping Volume 1 of 3
1993-06-01
paper. This work will present a passive piezoelectric damping implementation on ASTREX, a large space structure. The motivation behind this research is...Presented at Damping San Francisco, CA February 24-26, 1993 Motivation "• Accurate design of precision structures "* Computer modelling - Design...14) (KI f(0)/Fl,.) FRom equations (3) and (6), Young’s modulus of rubber specimen is written as; L Ea-K (15) A E - EJ(I+ PS4 ) (16) NONRESONANT TEST
Quantum damped oscillator I: Dissipation and resonances
International Nuclear Information System (INIS)
Chruscinski, Dariusz; Jurkowski, Jacek
2006-01-01
Quantization of a damped harmonic oscillator leads to so called Bateman's dual system. The corresponding Bateman's Hamiltonian, being a self-adjoint operator, displays the discrete family of complex eigenvalues. We show that they correspond to the poles of energy eigenvectors and the corresponding resolvent operator when continued to the complex energy plane. Therefore, the corresponding generalized eigenvectors may be interpreted as resonant states which are responsible for the irreversible quantum dynamics of a damped harmonic oscillator
International Nuclear Information System (INIS)
Edme, R.
1983-01-01
If a dynamic response analysis (harmonic excitation) is carried out with the modal method, the modal damping coefficients must be approximated to match the structural damping. The program ASKA-Damping, which also supplies an error assessment of the approximation, was developed for this purpose. The modal method and the direct method are applied to a test example and their results compared. It is suggested that the ASKA manufacturers extend the spectral earthquake response analysis to take these modal damping coefficients into account so that the results become less conservative. (orig.) [de
International Nuclear Information System (INIS)
Morecki, S.; Leshem, B.; Weigensberg, M.; Bar, S.; Slavin, S.
1985-01-01
Transplantation tolerance and stable chimerism were established in adult mice conditioned with a short course of total-lymphoid irradiation (TLI) followed by infusion of 30 X 10(6) allogeneic bone marrow cells. Spleen cells of tolerant mice could not exert a proliferative or cytotoxic response against host-type cells in vitro and were unable to induce graft-versus-host reaction in secondary host-type recipients. The degree of suppression assessed by coculturing tolerant splenocytes in vitro in the one-way mixed lymphocyte reaction was quite variable--and, in some cases, was not at all demonstrable, although tolerance was clearly maintained. Suppression, when apparent, could not be ascribed to T lymphocytes. Suppressor cells were found to bind soybean agglutinin and could be separated from the nonsuppressive cells by means of this lectin. Dissociation of the suppressive population (SBA+ cells) from that which is normally alloreactive (SBA- cells) resulted in a suppressor cell-depleted fraction that was still unable to respond to host-type cells but regained reactivity to unrelated cells. Limiting dilution analysis of chimeric splenocytes revealed markedly reduced frequencies of cytotoxic T lymphocyte precursors (CTL-P) directed against host-type cells, as compared with normal splenocytes reacting against the same target cells. This difference was accentuated when these cells were sensitized to host-type target cells prior to plating in limiting dilution cultures. In 1:1 mixing experiments of normal and chimeric splenocytes, there was no evidence of any in vitro suppressive activity to account for hyporeactivity of chimeric cells against host-type cells. Thus, maintenance of TLI-induced tolerance seemed not to be mediated primarily through an active suppressor cell mechanism
Bouman, Mark-Bram; van der Sluis, Wouter B; van Woudenberg Hamstra, Leonora E; Buncamper, Marlon E; Kreukels, Baudewijntje P C; Meijerink, Wilhelmus J H J; Mullender, Margriet G
2016-09-01
Puberty-suppressing hormonal treatment may result in penoscrotal hypoplasia in transgender women, making standard penile inversion vaginoplasty not feasible. For these patients, intestinal vaginoplasty is a surgical alternative, but knowledge on patient-reported postoperative outcomes and quality of life is lacking. To assess patient-reported functional and esthetic outcomes, quality of life, satisfaction, and sexual well-being after primary total laparoscopic intestinal vaginoplasty in transgender women. A survey study was performed on transgender women who underwent primary total laparoscopic intestinal vaginoplasty with at least 1 year of clinical follow-up. Thirty-one transgender women completed the questionnaires (median age at time of surgery = 19.1 years, range = 18.3-45.0) after a median clinical follow-up of 2.2 years (range = 0.8-7.5). Consenting women were asked to complete a combined questionnaire of the Subjective Happiness Scale, the Satisfaction With Life Scale, Cantril's Ladder of Life Scale, the Female Sexual Function Index, the Female Genital Self-Imaging Scale, the Amsterdam Hyperactive Pelvic Floor Scale-Women, and a questionnaire addressing postoperative satisfaction. Patient-reported functional and esthetic outcomes and postoperative quality of life. Patients graded their life satisfaction a median of 8.0 (range = 4.0-10.0) on Cantril's Ladder of Life Scale. Patients scored a mean total score of 27.7 ± 5.8 on the Satisfaction With Life Scale, which indicated high satisfaction with life, and a mean total score of 5.6 ± 1.4 on the Subjective Happiness Scale. Functionality was graded a median score of 8.0 of 10 (range = 1.0-10.0) and esthetics a score of 8.0 out of 10 (range = 3.0-10.0). The mean Female Sexual Function Index total score of sexually active transgender women was 26.0 ± 6.8. This group of relatively young transgender women reported satisfactory functional and esthetic results of the neovagina and a good quality of life
Electromagnetic damping of neutron star oscillations
International Nuclear Information System (INIS)
McDermott, P.N.; Savedoff, M.P.; Van Horn, H.M.; Zweibel, E.G.; Hansen, C.J.
1984-01-01
Nonradial pulsations of a neutron star with a strong dipole magnetic field cause emission of electromagnetic radiation. Here we compute the power radiated to vacuum by neutron star g-mode pulsations and by torsional oscillations of the neutron star crust. For the low-order quadrupole fluid g-modes we have considered, we find electromagnetic damping to be considerably more effective than gravitational radiation. For example, a 0.5 M/sub sun/ neutron star with a core temperature approx.10 7 K has a g 1 -mode period of 371 ms; for this mode were find the electromagnetic damping time to be tau/sub FM/approx.0.3 s, assuming the surface magnetic field strength of the neutron star to be B 0 approx.10 12 gauss. This is considerably less than the corresponding gravitational radiation time tau/sub GR/approx.3 x 10 17 yr. For dipole g-mode oscillations, there is no gravitational radiation, but electromagnetic damping and ohmic dissipation are efficient damping mechanisms. For dipole torsional oscillations, we find that electromagnetic damping again dominates, with tau/sub EM/approx.5 yr. Among the cases we have studied, quadrupole torsional oscillations appear to be dominated by gravitational radiation damping, with tau/sub GR/approx.10 4 yr, as compared with tau/sub EM/approx.2 x 10 7 yr
Piping system damping data at higher frequencies
International Nuclear Information System (INIS)
Ware, A.G.
1987-01-01
Research has been performed at the Idaho National Engineering Laboratory (INEL) for the United States Nuclear Regulatory Commission (USNRC) to determine best-estimate damping values for dynamic analyses of nuclear piping systems excited in the 20 to 100 Hz frequency range. Vibrations in this frequency range are typical of fluid-induced transients, for which no formal pipe damping guidelines exist. The available data found in the open literature and the USNRC/INEL nuclear piping damping data bank were reviewed, and a series of tests on a straight 3-in. (76-mm) piping system and a 5-in. (127-mm) system with several bends and elbows were conducted as part of this research program. These two systems were supported with typical nuclear piping supports that could be changed from test to test during the series. The resulting damping values were ≥ those of the Pressure Vessel Research Committee (PVRC) proposal for unisulated piping. Extending the PVRC damping curve from 20 to 100 Hz at 3% of critical damping would give a satisfactory representation of the test data. This position has been endorsed by the PVRC Technical Committee on Piping Systems. 14 refs
Oosting, Ellen; Hoogeboom, Thomas J; Appelman-de Vries, Suzan A; Swets, Adam; Dronkers, Jaap J; van Meeteren, Nico L U
2016-01-01
The aim of this study was to evaluate the value of conventional factors, the Risk Assessment and Predictor Tool (RAPT) and performance-based functional tests as predictors of delayed recovery after total hip arthroplasty (THA). A prospective cohort study in a regional hospital in the Netherlands with 315 patients was attending for THA in 2012. The dependent variable recovery of function was assessed with the Modified Iowa Levels of Assistance scale. Delayed recovery was defined as taking more than 3 days to walk independently. Independent variables were age, sex, BMI, Charnley score, RAPT score and scores for four performance-based tests [2-minute walk test, timed up and go test (TUG), 10-meter walking test (10 mW) and hand grip strength]. Regression analysis with all variables identified older age (>70 years), Charnley score C, slow walking speed (10 mW >10.0 s) and poor functional mobility (TUG >10.5 s) as the best predictors of delayed recovery of function. This model (AUC 0.85, 95% CI 0.79-0.91) performed better than a model with conventional factors and RAPT scores, and significantly better (p = 0.04) than a model with only conventional factors (AUC 0.81, 95% CI 0.74-0.87). The combination of performance-based tests and conventional factors predicted inpatient functional recovery after THA. Two simple functional performance-based tests have a significant added value to a more conventional screening with age and comorbidities to predict recovery of functioning immediately after total hip surgery. Patients over 70 years old, with comorbidities, with a TUG score >10.5 s and a walking speed >1.0 m/s are at risk for delayed recovery of functioning. Those high risk patients need an accurate discharge plan and could benefit from targeted pre- and postoperative therapeutic exercise programs.
Effective mass and damping of submerged structures
International Nuclear Information System (INIS)
Dong, R.G.
1978-01-01
Various structures important for safety in nuclear power plants must remain functioning in the event of an earthquake or other dynamic phenomenon. Some of these important structures, such as spent-fuel storage racks, main pressure-relief valve lines, and internal structures in the reactor vessel, are submerged in water. Dynamic analysis must include the force and damping effects of water. This report provides a technical basis for evaluating the wide variety of modeling assumptions currently used in design analysis. Current design analysis techniques and information in the literature form the basis of our conclusions and recommendations. We surveyed 32 industrial firms and reviewed 49 technical references. We compare various theories with published experimental results wherever possible. Our findings generally pertain to idealized structures, such as single isolated members, arrays of members, and coaxial cylinders. We relate these findings to the actual reactor structures through observations and recommendations. Whenever possible we recommend a definite way to evaluate the effect of hydrodynamic forces on these structures
Bencomo, Jose Antonio Fagundez
The main goal of this study was to relate physical changes in image quality measured by Modulation Transfer Function (MTF) to diagnostic accuracy. One Hundred and Fifty Kodak Min-R screen/film combination conventional craniocaudal mammograms obtained with the Pfizer Microfocus Mammographic system were selected from the files of the Department of Radiology, at M.D. Anderson Hospital and Tumor Institute. The mammograms included 88 cases with a variety of benign diagnosis and 62 cases with a variety of malignant biopsy diagnosis. The average age of the patient population was 55 years old. 70 cases presented calcifications with 30 cases having calcifications smaller than 0.5mm. 46 cases presented irregular bordered masses larger than 1 cm. 30 cases presented smooth bordered masses with 20 larger than 1 cm. Four separated copies of the original images were made each having a different change in the MTF using a defocusing technique whereby copies of the original were obtained by light exposure through different thicknesses (spacing) of transparent film base. The mammograms were randomized, and evaluated by three experienced mammographers for the degree of visibility of various anatomical breast structures and pathological lesions (masses and calicifications), subjective image quality, and mammographic interpretation. 3,000 separate evaluations were anayzed by several statistical techniques including Receiver Operating Characteristic curve analysis, McNemar test for differences between proportions and the Landis et al. method of agreement weighted kappa for ordinal categorical data. Results from the statistical analysis show: (1) There were no statistical significant differences in the diagnostic accuracy of the observers when diagnosing from mammograms with the same MTF. (2) There were no statistically significant differences in diagnostic accuracy for each observer when diagnosing from mammograms with the different MTF's used in the study. (3) There statistical
Directory of Open Access Journals (Sweden)
Scott D. Packard
2003-07-01
Full Text Available In order to identify differences in functional activity, we compared the reactivity of glioma vasculature and the native cerebral vasculature to both dilate and constrict in response to altered PaCO2. Gliomas were generated by unilateral implantation of U87MGdEGFR human glioma tumor cells into the striatum of adult female athymic rats. Relative changes in total and microvascular cerebral blood volume were determined by steady state contrast agent-enhanced magnetic resonance imaging for transitions from normocarbia to hypercarbia and hypocarbia. Although hypercarbia induced a significant increase in both total and microvascular blood volume in normal brain and glioma, reactivity of glioma vasculature was significantly blunted in comparison to normal striatum; glioma total CBV increased by 0.6±0.1%/mm Hg CO2 whereas normal striatum increased by 1.5±0.2%/mm Hg CO2, (P < .0001, group t-test. Reactivity of microvascular blood volume was also significantly blunted. In contrast, hypocarbia decreased both total and microvascular blood volumes more in glioma than in normal striatum. These results indicate that cerebral blood vessels derived by tumor-directed angiogenesis do retain reactivity to CO2. Furthermore, reduced reactivity of tumor vessels to a single physiological perturbation, such as hypercarbia, should not be construed as a generalized reduction of functional activity of the tumor vascular bed.
Wang, Fen; Zhou, Yingjie; Sun, Jiajun; Yang, Chunxi
2015-01-01
Continuous femoral nerve block (CFNB), guided by ultrasound combined nerve stimulations, offers advantages for both sides and provides effective postoperative analgesia after total knee arthroplasty (TKA). The objective of this study was to evaluate the medium-term impact of continuous femoral nerve block on knee function and quality of life in patients following TKA. This was a follow-up study. Total 168 adult patients scheduled for elective TKA were randomly allocated to receive postoperative continuous femoral nerve block guided by ultrasound combined nerve stimulator (group CFNB, n = 82) or patient-controlled epidural analgesia (group PCEA, n = 86). Quality of life, knee function, patient satisfaction, pain medication and associated adverse effects were compared at 1, 3, 6, and 12 months postoperatively. Quality of life was assessed using the Medical Outcomes Study Short Form-36 Health Survey (MOS SF-36), and clinical results were assessed using the Hospital for Special Surgery (HSS) Knee Scoring System. Patient satisfaction scores were divided into four categories. A total of 162 patients completed the 12-month follow-up. The CFNB group patients had significantly improved SF-36 scores and physical function at 1 month postoperatively (P quality of life in patients at one month postoperatively. Continuous femoral nerve block is a good choice for postoperative analgesia after TKA.
Gill, Aman S; Lee, Angela; McGuire, Krista L
2017-08-15
New York City (NYC) is pioneering green infrastructure with the use of bioswales and other engineered soil-based habitats to provide stormwater infiltration and other ecosystem functions. In addition to avoiding the environmental and financial costs of expanding traditional built infrastructure, green infrastructure is thought to generate cobenefits in the form of diverse ecological processes performed by its plant and microbial communities. Yet, although plant communities in these habitats are closely managed, we lack basic knowledge about how engineered ecosystems impact the distribution and functioning of soil bacteria. We sequenced amplicons of the 16S ribosomal subunit, as well as seven genes associated with functional pathways, generated from both total (DNA-based) and expressed (RNA) soil communities in the Bronx, NYC, NY, in order to test whether bioswale soils host characteristic bacterial communities with evidence for enriched microbial functioning, compared to nonengineered soils in park lawns and tree pits. Bioswales had distinct, phylogenetically diverse bacterial communities, including taxa associated with nutrient cycling and metabolism of hydrocarbons and other pollutants. Bioswale soils also had a significantly greater diversity of genes involved in several functional pathways, including carbon fixation ( cbbL-R [ cbbL gene, red-like subunit] and apsA ), nitrogen cycling ( noxZ and amoA ), and contaminant degradation ( bphA ); conversely, no functional genes were significantly more abundant in nonengineered soils. These results provide preliminary evidence that urban land management can shape the diversity and activity of soil communities, with positive consequences for genetic resources underlying valuable ecological functions, including biogeochemical cycling and degradation of common urban pollutants. IMPORTANCE Management of urban soil biodiversity by favoring taxa associated with decontamination or other microbial metabolic processes is a
Analysis of Simplifications Applied in Vibration Damping Modelling for a Passive Car Shock Absorber
Directory of Open Access Journals (Sweden)
Łukasz Konieczny
2016-01-01
Full Text Available The paper presents results of research on hydraulic automotive shock absorbers. The considerations provided in the paper indicate certain flaws and simplifications resulting from the fact that damping characteristics are assumed as the function of input velocity only, which is the case of simulation studies. An important aspect taken into account when determining parameters of damping performed by car shock absorbers at a testing station is the permissible range of characteristics of a shock absorber of the same type. The aim of this study was to determine the damping characteristics entailing the stroke value. The stroke and rotary velocities were selected in a manner enabling that, for different combinations, the same maximum linear velocity can be obtained. Thus the influence of excitation parameters, such as the stroke value, on force versus displacement and force versus velocity diagrams was determined. The 3D characteristics presented as the damping surface in the stoke and the linear velocity function were determined. An analysis of the results addressed in the paper highlights the impact of such factors on the profile of closed loop graphs of damping forces and point-type damping characteristics.
Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions
Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Campbell, Kenneth; Abrahamson, Norman; Silva, Walter
2012-01-01
Ground motion prediction equations (GMPEs) for elastic response spectra, including the Next Generation Attenuation (NGA) models, are typically developed at a 5% viscous damping ratio. In reality, however, structural and non-structural systems can have damping ratios other than 5%, depending on various factors such as structural types, construction materials, level of ground motion excitations, among others. This report provides the findings of a comprehensive study to develop a new model for a Damping Scaling Factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE to spectral ordinates with damping ratios between 0.5 to 30%. Using the updated, 2011 version of the NGA database of ground motions recorded in worldwide shallow crustal earthquakes in active tectonic regions (i.e., the NGA-West2 database), dependencies of the DSF on variables including damping ratio, spectral period, moment magnitude, source-to-site distance, duration, and local site conditions are examined. The strong influence of duration is captured by inclusion of both magnitude and distance in the DSF model. Site conditions are found to have less significant influence on DSF and are not included in the model. The proposed model for DSF provides functional forms for the median value and the logarithmic standard deviation of DSF. This model is heteroscedastic, where the variance is a function of the damping ratio. Damping Scaling Factor models are developed for the “average” horizontal ground motion components, i.e., RotD50 and GMRotI50, as well as the vertical component of ground motion.
Power system damping - Structural aspects of controlling active power
Energy Technology Data Exchange (ETDEWEB)
Samuelsson, O.
1997-04-01
Environmental and economical aspects make it difficult to build new power lines and to reinforce existing ones. The continued growth in demand for electric power must therefore to a great extent be met by increased loading of available lines. A consequence is that power system damping is reduced, leading to a risk of poorly damped power oscillations between the generators. This thesis proposes the use of controlled active loads to increase damping of such electro-mechanical oscillations. The focus is on structural aspects of controller interaction and of sensor and actuator placement. On-off control based on machine frequency in a single machine infinite bus system is analysed using energy function analysis and phase plane plots. An on-off controller with estimated machine frequency as input has been implemented. At a field test it damped oscillations of a 0.9 MW hydro power generator by controlling a 20kW load. The linear analysis uses two power system models with three and twenty-three machines respectively. Each damper has active power as output and local bus frequency or machine frequency as input. The power system simulator EUROSTAG is used both for generation of the linearized models and for time simulations. Measures of active power mode controllability and phase angle mode observability are obtained from the eigenvectors of the differential-algebraic models. The geographical variation in the network of these quantities is illustrated using the resemblance to bending modes of flexible mechanical structures. Eigenvalue sensitivities are used to determine suitable damper locations. A spring-mass equivalent to an inter-area mode provides analytical expressions, that together with the concept of impedance matching explain the structural behaviour of the power systems. For large gains this is investigated using root locus plots. 64 refs, 99 figs, 20 tabs
DAMPING OF ELECTRON DENSITY STRUCTURES AND IMPLICATIONS FOR INTERSTELLAR SCINTILLATION
International Nuclear Information System (INIS)
Smith, K. W.; Terry, P. W.
2011-01-01
The forms of electron density structures in kinetic Alfven wave (KAW) turbulence are studied in connection with scintillation. The focus is on small scales L ∼ 10 8 -10 10 cm where the KAW regime is active in the interstellar medium, principally within turbulent H II regions. Scales at 10 times the ion gyroradius and smaller are inferred to dominate scintillation in the theory of Boldyrev et al. From numerical solutions of a decaying KAW turbulence model, structure morphology reveals two types of localized structures, filaments and sheets, and shows that they arise in different regimes of resistive and diffusive damping. Minimal resistive damping yields localized current filaments that form out of Gaussian-distributed initial conditions. When resistive damping is large relative to diffusive damping, sheet-like structures form. In the filamentary regime, each filament is associated with a non-localized magnetic and density structure, circularly symmetric in cross section. Density and magnetic fields have Gaussian statistics (as inferred from Gaussian-valued kurtosis) while density gradients are strongly non-Gaussian, more so than current. This enhancement of non-Gaussian statistics in a derivative field is expected since gradient operations enhance small-scale fluctuations. The enhancement of density gradient kurtosis over current kurtosis is not obvious, yet it suggests that modest density fluctuations may yield large scintillation events during pulsar signal propagation. In the sheet regime the same statistical observations hold, despite the absence of localized filamentary structures. Probability density functions are constructed from statistical ensembles in both regimes, showing clear formation of long, highly non-Gaussian tails.
A lattice with larger momentum compaction for the NLC main damping rings
International Nuclear Information System (INIS)
Wolski, Andrzej; Raubenheimer, Tor O.; Woodley, Mark; Wu, Juhao
2004-01-01
Previous lattice designs for the Next Linear Collider Main Damping Rings [1] have met the specifications for equilibrium emittance, damping rate and dynamic aperture. Concerns about the effects of the damping wiggler on the beam dynamics [2] led to the aim of reducing the total length of the wiggler to a minimum consistent with the required damping rate, so high-field dipoles were used to provide a significant energy loss in the arcs. However, recent work has shown that the wiggler effects may not be as bad as previously feared. Furthermore, other studies have suggested the need for an increased momentum compaction (by roughly a factor of four) to raise the thresholds of various collective effects. We have therefore developed a new lattice design in which we increase the momentum compaction by reducing the field strength in the arc dipoles, compensating the loss in damping rate by increasing the length of the wiggler. The new lattice again meets the specifications for emittance, damping rate and dynamic aperture, while having the benefit of significantly higher thresholds for a number of instabilities
DEFF Research Database (Denmark)
Hagerhed, L.; Bornehag, Carl-Gustaf; Sundell, Jan
2002-01-01
Questionnaire data on 8681 dwellings included in the Swedish study "Dampness in Buildings and Health" have been analysed for associations between dampness indicators, perceptions of indoor air quality and building characteristics such as time of construction, type of ventilation and type of found......Questionnaire data on 8681 dwellings included in the Swedish study "Dampness in Buildings and Health" have been analysed for associations between dampness indicators, perceptions of indoor air quality and building characteristics such as time of construction, type of ventilation and type...... of "Dry air" in 17.3 and 33.7% respectively. Older buildings and the use of natural ventilation were associated with increased frequency of dampness indicators as well as to increased frequencies of complaints on bad indoor air quality....
Numerical studies of shear damped composite beams using a constrained damping layer
DEFF Research Database (Denmark)
Kristensen, R.F.; Nielsen, Kim Lau; Mikkelsen, Lars Pilgaard
2008-01-01
Composite beams containing one or more damping layers are studied numerically. The work is based on a semi-analytical model using a Timoshenko beam theory and a full 2D finite element model. The material system analysed, is inspired by a train wagon suspension system used in a EUREKA project Sigma......!1841. For the material system, the study shows that the effect of the damping layer is strongly influenced by the presence of a stiff constraining layer, that enforces large shear strain amplitudes. The thickness of the damping rubber layer itself has only a minor influence on the overall damping....... In addition, a large influence of ill positioned cuts in the damping layer is observed....
Damping and fluidelastic instability in two-phase cross-flow heat exchanger tube arrays
Moran, Joaquin E.
An experimental study was conducted to investigate damping and fluidelastic instability in tube arrays subjected to two-phase cross-flow. The purpose of this research was to improve our understanding of these phenomena and how they are affected by void fraction and flow regime. The model tube bundle had 10 cantilevered tubes in a parallel-triangular configuration, with a pitch ratio of 1.49. The two-phase flow loop used in this research utilized Refrigerant 11 as the working fluid, which better models steam-water than air-water mixtures in terms of vapour-liquid mass ratio as well as permitting phase changes due to pressure fluctuations. The void fraction was measured using a gamma densitometer, introducing an improvement over the Homogeneous Equilibrium Model (HEM) in terms of void fraction, density and velocity predictions. Three different damping measurement methodologies were implemented and compared in order to obtain a more reliable damping estimate. The methods were the traditionally used half-power bandwidth, the logarithmic decrement and an exponential fitting to the tube decay response. The decay trace was obtained by "plucking" the monitored tube from outside the test section using a novel technique, in which a pair of electromagnets changed their polarity at the natural frequency of the tube to produce resonance. The experiments showed that the half-power bandwidth produces higher damping values than the other two methods. The primary difference between the methods is caused by tube frequency shifting, triggered by fluctuations in the added mass and coupling between the tubes, which depend on void fraction and flow regime. The exponential fitting proved to be the more consistent and reliable approach to estimating damping. In order to examine the relationship between the damping ratio and mass flux, the former was plotted as a function of void fraction and pitch mass flux in an iso-contour plot. The results showed that damping is not independent of mass
Unwrapped phase inversion with an exponential damping
Choi, Yun Seok
2015-07-28
Full-waveform inversion (FWI) suffers from the phase wrapping (cycle skipping) problem when the frequency of data is not low enough. Unless we obtain a good initial velocity model, the phase wrapping problem in FWI causes a result corresponding to a local minimum, usually far away from the true solution, especially at depth. Thus, we have developed an inversion algorithm based on a space-domain unwrapped phase, and we also used exponential damping to mitigate the nonlinearity associated with the reflections. We construct the 2D phase residual map, which usually contains the wrapping discontinuities, especially if the model is complex and the frequency is high. We then unwrap the phase map and remove these cycle-based jumps. However, if the phase map has several residues, the unwrapping process becomes very complicated. We apply a strong exponential damping to the wavefield to eliminate much of the residues in the phase map, thus making the unwrapping process simple. We finally invert the unwrapped phases using the back-propagation algorithm to calculate the gradient. We progressively reduce the damping factor to obtain a high-resolution image. Numerical examples determined that the unwrapped phase inversion with a strong exponential damping generated convergent long-wavelength updates without low-frequency information. This model can be used as a good starting model for a subsequent inversion with a reduced damping, eventually leading to conventional waveform inversion.
On the normalization of total wave function of the system of an atom and a colliding electron
International Nuclear Information System (INIS)
Nashlenas, Eh.P.; Trinkunas, G.P.
1976-01-01
The scattering of an electron by an atom is considered which causes an excitation of fine structure levels. For this purpose the wave function of a system consisting of an atom and an uncoupled electron is constructed. Boundary conditions formulated in the form of an asymptotic expression are taken into account for such a function by means of scattering amplitudes. To determine scattering amplitudes it is suggested to make use of the condition of wave function normalization into the Dirac delta function. After certain mathematical transformations the unknown relations between the scattering amplitudes are obtained. The special cases of the relations obtained are discussed. When quantum numbers of the wave functions coincide, the resulting relations express the equality of fluxes of converging and diverging waves for a certain value of the total angular momentum. In the limiting case when there are no electrons in an atom (it corresponds to elastic scattering of an electron on a potential) the relations obtained express the unitarity conditions of the scattering matrix
Directory of Open Access Journals (Sweden)
Sunil K. Dash
Full Text Available ABSTRACT OBJECTIVE: Prospectively analyze the effect of preoperative walking status and the patient's surgical education on functional outcomes and the three dimensions of quality of life (QoL (pain, physical function, and mental health after elective total knee arthroplasty (TKA. METHODS: A comparative analysis on the QoL and functional outcomes in patients who underwent total knee arthroplasty between January 2014 and June 2015. To compare effects of the patient's walking status and knowledge of the surgical procedure on QoL and functional outcomes following TKA by means of SF-36 questionnaire, CES D10, VAS, KSS, KSFS, WOMAC, as well as Friedmann and Wyman scores, 10MWT, and 30-second timed chair test, assessed before the operation and one, three, and six months after the operation. RESULTS: There were 168 knees in 154 patients: 46.75% men and 53.24% women. 52.38% of knees had grade-III OA and 40.47% of knees had grade-IV OA. Preoperatively, SF-36 PCS was 33.2 and MCS was 35.4. Mean KSS and KSFS in females was 37.3 (16.2 and 31.5 (13.8; in males it was 49.2 (18.4 and 42.5 (15.7, respectively. Mean WOMAC scores were 64.2 in females and 56.5 in males. Mean VAS and CES D10 scores were 8.8 and 8.2 in females, and 6.9 and 6.4 in males, respectively. Post operatively at the first, third, and sixth month, significant improvements in QoL and mean SF-36, CES D10, VAS, KSS, KSFS, WOMAC, and Friedmann and Wyman scores were observed, as well as in the 10MWT and 30 s timed chair test scores. Patients with better preoperative functional activity and satisfactory understanding of TKA presented a better functional performance and achieved a good quality life (p< 0.01. DISCUSSION: Surgeons educate TKA candidates regarding the surgical procedure, the nature of implants, and how the procedure would affect their lifestyle and what their expectations from TKA should be. These crucial considerations should boost their confidence, enhancing their involvement and
Directory of Open Access Journals (Sweden)
Romakina N.A.
2016-06-01
Full Text Available Aim: to estimate functional status of coxarthrosis in patients requiring total hip replacement of the two hip joints. Material and methods. The biomechanical examination of 94 patients with bilateral primary coxarthrosis before and after total hip replacement was performed using clinical stabilometric software complex. The ability to perceive the mechanical load during standing and walking was evaluated at different stages of the treatment. The difference between the samples was estimated with the use of Mann — Whitney U-test. The rank correlation of biomechanical parameters was measured by Spearman coefficient. Results. It was revealed that the most responsive indicators are the transfer period, the first and second periods of double support and the deviation of the center of pressure relative to the average position in the frontal plane. Conclusion. After surgical treatment there was observed some improvement: the-left-and-right-step asymmetry decrease, rhythm rate increase, improved ability to maintain body balance, jog reactions increase.
DEFF Research Database (Denmark)
Reardon, Hazel; Iversen, Bo Brummerstedt; Blichfeld, Anders Bank
-I clathrate Ba8Ga16Ge30. This suggests that local structure reorientations in the cage are likely to be the root cause of the degradation of the structure. This deepens our understanding of disordered clathrates, and provides evidence that the PDF technique is an effective method for probing local structure.......e., by measuring both the Bragg and diffuse scattering from a sample. This method has rarely been exploited by the non-oxide thermoelectrics community. , , Treating total scattering data by the Pair Distribution Function method is a logical approach to understanding defects, disorder and amorphous components...... to heating cycles, then we are closer to distinguishing how we may generate materials that do not undergo specific structure reorientation processes, and/or how we may mitigate them before they occur. Here, we will present a total scattering and PDF study that probes the local structure of the Type...
Fujiwara, Takeo; Nishino, Shinya; Yamamoto, Susumu; Suzuki, Takashi; Ikeda, Minoru; Ohtani, Yasuaki
2018-06-01
A novel tight-binding method is developed, based on the extended Hückel approximation and charge self-consistency, with referring the band structure and the total energy of the local density approximation of the density functional theory. The parameters are so adjusted by computer that the result reproduces the band structure and the total energy, and the algorithm for determining parameters is established. The set of determined parameters is applicable to a variety of crystalline compounds and change of lattice constants, and, in other words, it is transferable. Examples are demonstrated for Si crystals of several crystalline structures varying lattice constants. Since the set of parameters is transferable, the present tight-binding method may be applicable also to molecular dynamics simulations of large-scale systems and long-time dynamical processes.
Yigit, Ufuk; Cigeroglu, Ender; Budak, Erhan
2017-09-01
Chatter is a self-excited type of vibration that develops during machining due to process-structure dynamic interactions resulting in modulated chip thickness. Chatter is an important problem as it results in poor surface quality, reduced productivity and tool life. The stability of a cutting process is strongly influenced by the frequency response function (FRF) at the cutting point. In this study, the effect of piezoelectric shunt damping on chatter vibrations in a boring process is studied. In piezoelectric shunt damping method, an electrical impedance is connected to a piezoelectric transducer which is bonded on cutting tool. Electrical impedance of the circuit consisting of piezoceramic transducer and passive shunt is tuned to the desired natural frequency of the cutting tool in order to maximize damping. The optimum damping is achieved in analytical and finite element models (FEM) by using a genetic algorithm focusing on the real part of the tool point FRF rather than the amplitude. Later, a practical boring bar is considered where the optimum circuit parameters are obtained by the FEM. Afterwards, the effect of the optimized piezoelectric shunt damping on the dynamic rigidity and absolute stability limit of the cutting process are investigated experimentally by modal analysis and cutting tests. It is both theoretically and experimentally shown that application of piezoelectric shunt damping results in a significant increase in the absolute stability limit in boring operations.
Tuning of damping controller for UPFC using quantum particle swarm optimizer
Energy Technology Data Exchange (ETDEWEB)
Shayeghi, H., E-mail: hshayeghi@gmail.co [Technical Engineering Department, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Shayanfar, H.A. [Center of Excellence for Power System Automation and Operation, Electrical Engineering Department, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Jalilzadeh, S.; Safari, A. [Technical Engineering Department, Zanjan University, Zanjan (Iran, Islamic Republic of)
2010-11-15
On the basis of the linearized Phillips-Herffron model of a single machine power system, we design optimally the unified power flow controller (UPFC) based damping controller in order to enhance power system low frequency oscillations. The problem of robustly UPFC based damping controller is formulated as an optimization problem according to the time domain-based objective function which is solved using quantum-behaved particle swarm optimization (QPSO) technique that has fewer parameters and stronger search capability than the particle swarm optimization (PSO), as well as is easy to implement. To ensure the robustness of the proposed damping controller, the design process takes into account a wide range of operating conditions and system configurations. The effectiveness of the proposed controller is demonstrated through non-linear time-domain simulation and some performance indices studies under various disturbance conditions of over a wide range of loading conditions. The results analysis reveals that the designed QPSO based UPFC controller has an excellent capability in damping power system low frequency oscillations in comparison with the designed classical PSO (CPSO) based UPFC controller and enhance greatly the dynamic stability of the power systems. Moreover, the system performance analysis under different operating conditions show that the {delta}{sub E} based damping controller is superior to the m{sub B} based damping controller.
Emergent large mechanical damping in ferroelastic-martensitic systems driven by disorder
Ni, Yan; Zhang, Zhen; Fang, Minxia; Hao, Yanshuang; Ding, Xiangdong; Otsuka, Kazuhiro; Ren, Xiaobing
2018-05-01
Disorders and point defects strongly interplay with the phase transition and alter the properties of ferroelastic-martensitic systems. Unusual static and quasistatic behaviors, such as time-dependent phase transitions, are discovered when disorders are introduced. However, the role of disorders on the ferroelastic system in vibrational environments at moderate frequency is rarely known, investigation of which could further shed light on their application as mechanical damping materials. Here we present the emergence of large damping capacity in ferroelastic-martensitic systems [including both the T i50 -xN i50 +x alloy and (C a1 -xS rx) Ti O3 ceramics] by introducing disorder (i.e., substitutional Ni and Sr, respectively). As the level disorder increases, the damping capacity of both systems raises and eventually reaches a maximum when long-range-ordered martensite tends to vanish. Moreover, near the disorder-induced phase boundary, we observe a large mechanical damping in ferroelastic ceramics (C a1 -xS rx) Ti O3 with a figure of merit ˜2 GP a1 /2 . Microscopic and dynamic investigations indicate that such damping plateau could result from the competing evolution of density and mobility of domain boundaries when disorder is introduced. Our work provides a degree of freedom to develop ferroelastic damping materials and a potential way to tune domain-boundary-mediated functionalities for other ferroic materials.
Dron, J; Zheng, W; Marchand, N; Wortham, H
2008-08-01
A functional group analysis method was developed to determine the quantitative content of carbonyl functional groups in atmospheric particulate organic matter (POM) using constant neutral loss scanning-tandem mass spectrometry (CNLS-MS/MS). The neutral loss method consists in monitoring the loss of a neutral fragment produced by the fragmentation of a precursor ion in a collision cell. The only ions detected are the daughter ions resulting from the loss of the neutral fragment under study. Then, scanning the loss of a neutral fragment characteristic of a functional group enables the selective detection of the compounds bearing the chemical function under study within a complex mixture. The selective detection of carbonyl functional groups was achieved after derivatization with pentafluorophenylhydrazine (PFPH) by monitoring the neutral loss of C(6)F(5)N (181 amu), which was characteristic of a large panel of derivatized carbonyl compounds. The method was tested on 25 reference mixtures of different composition, all containing 24 carbonyl compounds at randomly determined concentrations. The repeatability and calibration tests were satisfying as they resulted in a relative standard deviation below 5% and a linear range between 0.01 and 0.65 mM with a calculated detection limit of 0.0035 mM. Also, the relative deviation induced by changing the composition of the mixture while keeping the total concentration of carbonyl functional groups constant was less than 20%. These reliability experiments demonstrate the high robustness of the developed procedure for accurate carbonyl functional group measurement, which was applied to atmospheric POM samples. Copyright (c) 2008 John Wiley & Sons, Ltd.
Damping in heat exchanger tube bundles. A review
International Nuclear Information System (INIS)
Iqbal, Qamar; Khushnood, Shahab; Ghalban, Ali Roheim El; Sheikh, Nadeem Ahmed; Malik, Muhammad Afzaal; Arastu, Asif
2007-01-01
Damping is a major concern in the design and operation of tube bundles with loosely supported tubes in baffles for process shell and tube heat exchangers and steam generators which are used in nuclear, process and power generation industries. System damping has a strong influence on the amplitude of vibration. Damping depends upon the mechanical properties of the tube material, geometry of intermediate supports and the physical properties of shell-side fluid. Type of tube motion, number of supports, tube frequency, vibration amplitude, tube mass or diameter, side loads, support thickness, higher modes, shell-side temperature etc., affect damping in tube bundles. The importance of damping is further highlighted due to current trend of larger exchangers with increased shell-side velocities in modern units. Various damping mechanisms have been identified (Friction damping, Viscous damping, Squeeze film damping, Support damping. Two-Phase damping, and very recent-Thermal damping), which affect the performance of process exchangers and steam generators with respect to flow induced vibration design, including standard design guidelines. Damping in two-phase flow is very complex and highly void fraction, and flow-regime dependent. The current paper focuses on the various known damping mechanisms subjected to both single and two-phase cross-flow in process heat exchangers and steam generators and formulates the design guidelines for safer design. (author)
Martin, Alex D; Siamaki, Ali R; Belecki, Katherine; Gupton, B Frank
2015-02-06
A direct and efficient total synthesis has been developed for telmisartan, a widely prescribed treatment for hypertension. This approach brings together two functionalized benzimidazoles using a high-yielding Suzuki reaction that can be catalyzed by either a homogeneous palladium source or graphene-supported palladium nanoparticles. The ability to perform the cross-coupling reaction was facilitated by the regio-controlled preparation of the 2-bromo-1-methylbenzimidazole precursor. This convergent approach provides telmisartan in an overall yield of 72% while circumventing many issues associated with previously reported processes.
Nuclear power plant piping damping parametric effects
International Nuclear Information System (INIS)
Ware, A.G.
1983-01-01
The NRC and EG and G Idaho are engaged in programs to evaluate piping-system damping, in order to provide realistic and less conservative values to be used in seismic analyses. To generate revised guidelines, solidly based on technical data, new experimental data need to be generated and assessed, and the parameters which influence piping-system damping need to be quantitatively identified. This paper presents the current state-of-the-art knowledge in the United States on parameters which influence piping-system damping. Examples of inconsistencies in the data and areas of uncertainty are explained. A discussion of programs by EG and G Idaho and other organizations to evaluate various effects are included, and both short-and long-range goals of the program are outlined
Radiation damping in focusing-dominated systems
International Nuclear Information System (INIS)
Huang, Zhirong; Chen, Pisin; Ruth, R.D.
1995-01-01
A quasi-classical method is developed to calculate the radiation damping of a relativistic particle in a straight, continuous focusing system. In one limiting case where the pitch angle of the particle θ p is much larger than the radiation opening angle 1/γ, the radiation power spectrum is similar to synchrotron radiation and the relative damping rate of the transverse action is proportional to the relative energy loss rate. In the other limiting case where θ p much-lt 1/γ, the radiation is dipole in nature and the relative damping rate of the transverse action is energy-independent and is much faster than the relative energy rate. Quantum excitation to the transverse action is absent in this focusing channel. These results can be extended to bent systems provided that the focusing field dominates over the bending field
Damping of wind turbine tower vibrations
DEFF Research Database (Denmark)
Brodersen, Mark Laier; Pedersen, Mikkel Melters
Damping of wind turbine vibrations by supplemental dampers is a key ingredient for the continuous use of monopiles as support for offshore wind turbines. The present thesis consists of an extended summary with four parts and appended papers [P1-P4] concerning novel strategies for damping of tower...... dominated vibrations.The first part of the thesis presents the theoretical framework for implementation of supplemental dampers in wind turbines. It is demonstrated that the feasibility of installing dampers at the bottom of the tower is significantly increased when placing passive or semiactive dampers...... in a stroke amplifying brace, which amplifies the displacement across the damper and thus reduces the desired level of damper force. For optimal damping of the two lowest tower modes, a novel toggle-brace concept for amplifying the bending deformation of the tower is presented. Numerical examples illustrate...
Directory of Open Access Journals (Sweden)
LEE MEISEL
2005-01-01
Full Text Available Prunus persica has been proposed as a genomic model for deciduous trees and the Rosaceae family. Optimized protocols for RNA isolation are necessary to further advance studies in this model species such that functional genomics analyses may be performed. Here we present an optimized protocol to rapidly and efficiently purify high quality total RNA from peach fruits (Prunus persica. Isolating high-quality RNA from fruit tissue is often difficult due to large quantities of polysaccharides and polyphenolic compounds that accumulate in this tissue and co-purify with the RNA. Here we demonstrate that a modified version of the method used to isolate RNA from pine trees and the woody plant Cinnamomun tenuipilum is ideal for isolating high quality RNA from the fruits of Prunus persica. This RNA may be used for many functional genomic based experiments such as RT-PCR and the construction of large-insert cDNA libraries.
DEFF Research Database (Denmark)
Lunn, T H; Kristensen, B B; Gaarn-Larsen, L
2012-01-01
anaesthesia and analgesia underwent an exercise (mobilisation) strategy on the first post-operative morning consisting of 25-m walking twice, with a 20-min interval. Pain was assessed at rest and during passive hip and knee flexion before, and 5 and 20 min after walk, as well as during walk. Nociceptive......BACKGROUND: Experimental studies in animals, healthy volunteers, and patients with chronic pain suggest exercise to provide analgesia in several types of pain conditions and after various nociceptive stimuli. To our knowledge, there is no data on the effects of exercise on pain and nociceptive...... function in surgical patients despite early mobilisation being an important factor to enhance recovery. We therefore investigated possible effects of mobilisation on post-operative pain and nociceptive function after total knee arthroplasty (TKA). METHODS: Thirty patients undergoing TKA under standardised...
Thoa, Dao Thi Kim; Loc, Luu Cam
2017-09-01
The effect of both total pressure and hydrogen partial pressure during n-hexane hydro-isomerization over platinum impregnated on HZSM-5 was studied. n-Hexane hydro-isomerization was conducted at atmospheric pressure and 0.7 MPa to observe the influence of total pressure. In order to see the effect of hydrogen partial pressure, the reaction was taken place at different partial pressure of hydrogen varied from 307 hPa to 718 hPa by dilution with nitrogen to keep the total pressure at 0.1 MPa. Physico-chemical characteristics of catalyst were determined by the methods of nitrogen physi-sorption BET, SEM, XRD, TEM, NH3-TPD, TPR, and Hydrogen Pulse Chemi-sorption. Activity of catalyst in the hydro-isomerization of n-hexane was studied in a micro-flow reactor in the temperature range of 225-325 °C; the molar ratio H2/ hydrocarbon: 5.92, concentration of n-hexane: 9.2 mol.%, GHSV 2698 h-1. The obtained catalyst expressed high acid density, good reducing property, high metal dispersion, and good balance between metallic and acidic sites. It is excellent contact for n-hexane hydro-isomerization. At 250 °C, n-hexane conversion and selectivity were as high as 59-76 % and 85-99 %, respectively. It was found that catalytic activity was promoted either by total pressure or hydrogen partial pressure. At total pressure of 0.7 MPa while hydrogen partial pressure of 718 hPa, catalyst produced 63 RON liquid product containing friendly environmental iso-paraffins which is superior blending stock for green gasoline. Hydrogen did not only preserve catalyst actives by depressing hydrocracking and removing coke precursors but also facilitated hydride transfer step in the bi-functional bi-molecular mechanism.
Rajgopal, Ashok; Aggarwal, Kalpana; Khurana, Anshika; Rao, Arun; Vasdev, Attique; Pandit, Hemant
2017-01-01
Total knee arthroplasty is a well-established treatment for managing end-stage symptomatic knee osteoarthritis. Currently, different designs of prostheses are available with majority ensuring similar clinical outcomes. Altered surface geometry is introduced to strive toward gaining superior outcomes. We aimed to investigate any differences in functional outcomes between 2 different polyethylene designs namely the Persona CR (cruciate retaining) and Persona UC (ultracongruent) tibial inserts (Zimmer-Biomet, Warsaw, IN). This prospective single blind, single-surgeon randomized controlled trial reports on 105 patients, (66 female and 39 male), who underwent simultaneous bilateral total knee arthroplasty using the Persona knee system (Zimmer-Biomet) UC inserts in one side and CR inserts in the contralateral side. By a blind assessor, at regular time intervals patients were assessed in terms of function and gait. The functional knee scoring scales used were the Western Ontario and McMaster Universities Osteoarthritis Index and Modified Knee Society Score. The gait parameters evaluated were foot pressure and step length. During the study period, no patient was lost to follow-up or underwent revision surgery for any cause. Western Ontario and McMaster Universities Osteoarthritis Index scores, Modified Knee Society Score, and knee range of motion of all 105 patients assessed preoperatively and postoperatively at 6 months, 1 year, and 2 years showed statistically better results (P < .05) for UC inserts. Gait analysis measuring foot pressures and step length, however, did not show any statistically significant differences at 2-year follow-up. Ultracongruent tibial inserts show significantly better functional outcomes as compared to CR inserts during a 2-year follow-up period. However, in this study these findings were not shown to be attributed to differences in gait parameters. Copyright © 2016 Elsevier Inc. All rights reserved.
Quantization of the damped harmonic oscillator revisited
Energy Technology Data Exchange (ETDEWEB)
Baldiotti, M.C., E-mail: baldiott@fma.if.usp.b [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil); Fresneda, R., E-mail: fresneda@gmail.co [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil); Gitman, D.M., E-mail: gitman@dfn.if.usp.b [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318-CEP, 05315-970 Sao Paulo, S.P. (Brazil)
2011-04-11
We return to the description of the damped harmonic oscillator with an assessment of previous works, in particular the Bateman-Caldirola-Kanai model and a new model proposed by one of the authors. We argue the latter has better high energy behavior and is connected to existing open-systems approaches. - Highlights: We prove the local equivalence of two damped harmonic oscillator models. We find different high energy behaviors between the two models. Based on the local equivalence, we make a simple construction of the coherent states.
Quantization of the damped harmonic oscillator revisited
International Nuclear Information System (INIS)
Baldiotti, M.C.; Fresneda, R.; Gitman, D.M.
2011-01-01
We return to the description of the damped harmonic oscillator with an assessment of previous works, in particular the Bateman-Caldirola-Kanai model and a new model proposed by one of the authors. We argue the latter has better high energy behavior and is connected to existing open-systems approaches. - Highlights: → We prove the local equivalence of two damped harmonic oscillator models. → We find different high energy behaviors between the two models. → Based on the local equivalence, we make a simple construction of the coherent states.
Variable stiffness and damping MR isolator
Energy Technology Data Exchange (ETDEWEB)
Zhang, X Z; Wang, X Y; Li, W H; Kostidis, K [University of Wollongong, School of Mechanical, Materials and Mechatronic Engineering, NSW 2522 (Australia)], E-mail: weihuali@uow.edu.au
2009-02-01
This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness and damping isolator for vibration suppressions. The MR fluid isolator used a sole MR control unit to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, and a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The parameters of the model under various magnetic fields were identified and the dynamic performances of isolator were evaluated.
Damping in accelerators due to classical radiation
International Nuclear Information System (INIS)
Mills, F.E.
1962-01-01
The rates of change of the magnitudes of the adiabatic invariants is calculated in the case of a Hamiltonian system subjected to generalized non conservative forces. These results are applied to the case of the classical radiation of electrons in an accelerator or storage ring. The resulting expressions for the damping rates of three independent oscillation modes suggest structures which are damping in all three modes, while at the same time allowing 'strong focussing' and the attendant strong momentum compaction. (author)
Modulated Langmuir waves and nonlinear Landau damping
International Nuclear Information System (INIS)
Yajima, Nobuo; Oikawa, Masayuki; Satsuma, Junkichi; Namba, Chusei.
1975-01-01
The nonlinear Schroedinger euqation with an integral term, iusub(t)+P/2.usub(xx)+Q/u/ 2 u+RP∫sub(-infinity)sup(infinity)[/u(x',t)/ 2 /(x-x')]dx'u=0, which describes modulated Langmuir waves with the nonlinear Landau damping effect, is solved by numerical calculations. Especially, the effects of nonlinear Landau damping on solitary wave solutions are studied. For both cases, PQ>0 and PQ<0, the results show that the solitary waves deform in an asymmetric way changing its velocity. (auth.)
Ha, Chul-Won; Park, Yong-Beom; Song, Young-Suk; Kim, Jun-Ho; Park, Yong-Geun
2016-06-01
Although range of motion (ROM) is considered as an important factor for good outcome after total knee arthroplasty (TKA), the association of the degree of ROM with functional outcome and patient satisfaction is debated. We, therefore, investigated whether increased ROM would affect functional outcome and patient satisfaction after TKA in Asian patients. We reviewed 630 patients who underwent primary TKA with minimum 2-year follow-up. Clinical outcomes were evaluated by Knee Society (KS) score, Western Ontario and McMaster Universities osteoarthritis index, and high-flexion knee score. Patient satisfaction was evaluated using a validated questionnaire. The association of ROM and change in ROM (cROM) with clinical outcomes and satisfaction were analyzed using partial correlation analysis and multiple median regression analysis. All functional scores showed significant correlation with postoperative ROM (r = 0.129, P = .001 in Knee Society score; r = -0.101, P = .012 in Western Ontario and McMaster Universities osteoarthritis index; r = 0.183, P satisfaction (r = 0.192, P = .005). Postoperative ROM and cROM were revealed as predisposing factors affecting function outcome using multivariable regression analysis. cROM was found as a predisposing factor affecting satisfaction. Based on the results of this study, ROM positively associated with functional outcome and cROM positively associated with patient satisfaction after TKA. These findings suggest that increased ROM after TKA is an important factor for functional outcome and satisfaction in Asian patients. Copyright © 2015 Elsevier Inc. All rights reserved.
Damping of multispan heat exchanger tubes. Pt. 1: in gases
International Nuclear Information System (INIS)
Pettigrew, M.J.; Goyder, H.G.D.; Qiao, Z.L.; Axisa, F.
1986-07-01
Flow-induced vibration analyses of heat exchanger tubes require the knowledge of damping. This paper treats the question of damping on multispan heat exchanger tubes in air and gases. The different energy dissipation mechanisms that contribute to tube damping are discussed. The available experimental data are reviewed and analysed. We find that the main damping mechanism in gases is friction between tube and tube-supports. Damping is strongly related to tube-support thickness. Damping values are recommended for design purposes. This study is interesting in the nuclear industry for it often uses heat exchangers
Hou, Junfang; jing, Min; Zhang, Weihua; Lu, Yahui; He, Haiwen
2017-12-01
As for the isolation problem of electronic equipments on vehicle, the vibration response characteristics of dry friction damping isolation system under base displacement excitation was analyzed in theory by harmonic balance method, and the displacement response was compared between the isolation systems with dry friction damping and vicious damping separately. The results show that the isolation system with small dry friction damping can’t meet the demands of displacement reduction close to the natural frequency, and it can realize full-frequency vibration isolation by improving dry friction damping when the lock frequency passes beyond the resonance frequency band. The results imply that the damping mechanism of dry friction isolator can’t be described only by dry friction damping, and the composite damping with dry friction and vicious damping is more appropriate.
DEFF Research Database (Denmark)
Holm, Bente; Kristensen, Morten Tange; Husted, Henrik
2011-01-01
OBJECTIVE: To (1) quantify changes in knee-extension strength and functional-performance at discharge after fast-track total hip arthroplasty (THA) and (2) investigate whether these changes correlate to changes in thigh and knee circumference (ie, swelling) or pain. DESIGN: A prospective, descrip......OBJECTIVE: To (1) quantify changes in knee-extension strength and functional-performance at discharge after fast-track total hip arthroplasty (THA) and (2) investigate whether these changes correlate to changes in thigh and knee circumference (ie, swelling) or pain. DESIGN: A prospective......, descriptive, hypothesis-generating study. SETTING: A special unit for fast-track hip and knee arthroplasty operations at a university hospital. PARTICIPANTS: Twenty-four patients (20 women and 4 men; ages 69 ± 6.1 years) scheduled for primary unilateral THA. METHODS: All patients were evaluated before surgery......, except for hip pain. The average loss in knee-extension strength after surgery (32%, P = .01) did not correlate with increased thigh circumference (6%, P
International Nuclear Information System (INIS)
Struis, Rudolf P.W.J.; Ludwig, Christian; Barrelet, Timothee; Kraehenbuehl, Urs; Rennenberg, Heinz
2008-01-01
Profiles of the major sulfur functional groups in mature Norway spruce wood tissue have been established for the first time. The big challenge was the development of a method suitable for sulfur speciation in samples with very low sulfur content (< 100 ppm). This became possible by synchrotron X-ray absorption spectroscopy at the sulfur L-edge in total electron yield (TEY) detection mode with thin gold-coated wood slices. Functional groups were identified using sulfur compound spectra as fingerprints. Latewood of single year rings revealed metabolic plausible sulfur forms, particularly inorganic sulfide, organic disulfide, methylthiol, and highly oxidized sulfur. Form-specific profiles with Norway spruces from three different Swiss forest sites revealed high, but hitherto little-noticed, sulfur intensities attributable to natural heartwood formation and a common, but physiologically unexpected maximum around year ring 1986 with trees from the industrialized Swiss Plateau. It is hypothesized whether it may have resulted from the huge reduction in sulfur emissions after 1980 due to Swiss policy. Comparison with total S content profiles from optical emission spectroscopy underlined the more accurate and temporally better resolved TEY data with single wood year rings and it opened novel insights into the wood cell chemistry
Townsend, M C; Enterline, P E; Sussman, N B; Bonney, T B; Rippey, L L
1985-12-01
A cross-sectional study of 1,142 male employees at the Arkansas Operations of a large aluminum production company examined the effect on pulmonary function of chronic exposure to total dust produced in the mining and refining of bauxite and the production of alumina chemicals. Never smokers, ex-smokers, and current smokers were analyzed separately. Among never smokers, a pattern of decreasing FEV1 was observed in relation to increasing duration and cumulative total dust exposure. Among never smokers with cumulative total dust exposures of greater than or equal to 100 mg/m3 yr and greater than or equal to 20 yr of exposure, there was a mean reduction from the predicted FEV1 of 0.29 to 0.39 L, in addition to a 3- to 4-fold excess of observed/expected numbers of subjects with FEV1 less than 80% of predicted. These results were observed relative to an external and an internal comparison group. Among current smokers, the deviations from predicted and the excess numbers of subjects with FEV1 less than 80% of predicted were larger in all exposure groups than for the never smokers. However, the quality of the smoking data was inadequate to allow separation of the effects of smoking and dust exposure.
Effect of Stress Amplitude on the Damping of Recycled Aggregate Concrete.
Liang, Chaofeng; Liu, Tiejun; Xiao, Jianzhuang; Zou, Dujian; Yang, Qiuwei
2015-08-14
Damping characterizes the energy dissipation capacity of materials and structures, and it is affected by several external factors such as vibrating frequency, stress history, temperature, and stress amplitude. This study investigates the relationship between the damping and the stress amplitude of environment-friendly recycled aggregate concrete (RAC). First, a function model of a member's loss factor and stress amplitude was derived based on Lazan's damping-stress function. Then, the influence of stress amplitude on the loss tangent of RAC was experimentally investigated. Finally, parameters used to determine the newly derived function were obtained by numerical fitting. It is shown that the member's loss factor is affected not only by the stress amplitude but also by factors such as the cross section shapes, boundary conditions, load types, and loading positions. The loss tangent of RAC increases with the stress amplitude, even at low stress amplitude. The damping energy exponent of RAC is not identically equal to 2.0, indicating that the damping is nonlinear. It is also found that the energy dissipation capacity of RAC is superior to that of natural aggregate concrete (NAC), and the energy dissipation capacity can be further improved by adding modified admixtures.
Gravitational radiation resistance, radiation damping and field fluctuations
International Nuclear Information System (INIS)
Schaefer, G.
1981-01-01
Application is made of two different generalised fluctuation-dissipation theorems and their derivations to the calculation of the gravitational quadrupole radiation resistance using the radiation-reaction force given by Misner, Thorne and Wheeler (Gravitation (San Francisco: Freeman) ch 36,37 (1973)) and the usual tidal force on one hand and the tidal force and the free gravitational radiation field on the other hand. The quantum-mechanical version (including thermal generalisations) of the well known classical quadrupole radiation damping formula is obtained as a function of the radiation resistance. (author)
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Gaididei, Yuri Borisovich; Rasmussen, Kim
1996-01-01
in an exponentially decreasing width of the solution in the long-time limit. We also find that a sufficiently large noise variance may cause an initially localized distribution to spread instead of contracting, and that the critical variance necessary to cause dispersion will for small damping be the same......We study the effect of adding noise and nonlinear damping in the two-dimensional nonlinear Schrodinger equation (NLS). Using a collective approach, we find that for initial conditions where total collapse occurs in the unperturbed NLS, the presence of the damping term will instead...
The effect of dust size distribution on the damping of the solitary waves in a dusty plasma
International Nuclear Information System (INIS)
Yang, Xue; Xu, Yan-Xia; Qi, Xin; Wang, Cang-Long; Duan, Wen-Shan; Yang, Lei
2013-01-01
The effect of the dust size distribution on the damping rate of the solitary wave in a dusty plasma is investigated in the present paper. It is found that the damping rate increases as either the mean radius of dust grains increases or as the total number density of the dust grains increases. The damping rate is less for usual dusty plasma (about which the number density of the smaller dust grains is larger than that of the larger dust grains) than that of the unusual dusty plasma (about which the number density of the larger dust grains is larger than that of the smaller dust grains)
Directory of Open Access Journals (Sweden)
A. Qi
2016-01-01
Full Text Available This study aimed to determine whether psychological factors affect health-related quality of life (HRQL and recovery of knee function in total knee replacement (TKR patients. A total of 119 TKR patients (male: 38; female: 81 completed the Beck Anxiety Inventory (BAI, Beck Depression Inventory (BDI, State Trait Anxiety Inventory (STAI, Eysenck Personality Questionnaire-revised (EPQR-S, Knee Society Score (KSS, and HRQL (SF-36. At 1 and 6 months after surgery, anxiety, depression, and KSS scores in TKR patients were significantly better compared with those preoperatively (P<0.05. SF-36 scores at the sixth month after surgery were significantly improved compared with preoperative scores (P<0.001. Preoperative Physical Component Summary Scale (PCS and Mental Component Summary Scale (MCS scores were negatively associated with extraversion (E score (B=-0.986 and -0.967, respectively, both P<0.05. Postoperative PCS and State Anxiety Inventory (SAI scores were negatively associated with neuroticism (N score; B=-0.137 and -0.991, respectively, both P<0.05. Postoperative MCS, SAI, Trait Anxiety Inventory (TAI, and BAI scores were also negatively associated with the N score (B=-0.367, -0.107, -0.281, and -0.851, respectively, all P<0.05. The KSS function score at the sixth month after surgery was negatively associated with TAI and N scores (B=-0.315 and -0.532, respectively, both P<0.05, but positively associated with the E score (B=0.215, P<0.05. The postoperative KSS joint score was positively associated with postoperative PCS (B=0.356, P<0.05. In conclusion, for TKR patients, the scores used for evaluating recovery of knee function and HRQL after 6 months are inversely associated with the presence of negative emotions.
An efficient delivery of DAMPs on the cell surface by the unconventional secretion pathway
International Nuclear Information System (INIS)
Zhu, Haiyan; Wang, Lan; Ruan, Yuanyuan; Zhou, Lei; Zhang, Dongmei; Min, Zhihui; Xie, Jianhui; Yu, Min; Gu, Jianxin
2011-01-01
Research highlights: → Hsp60 transported to cell surface through the classical secretory pathway was modified with N-glycosylation. → HSAPB-N18 could efficiently deliver Hsp60 to the cell surface via the unconventional secretory pathway. → Cell surface Hsp60 delivered by HASPB-N18 has a proper conformation. → HASPB-N18 is an efficient delivery signal for other DAMP molecules such as Hsp70 and HMGB1. -- Abstract: Damage-associated molecular patterns (DAMPs) are signals released from dying cells evoking the immune system response in several inflammatory disorders. In normal situations, many of DAMPs are nuclear or cytosolic proteins with defined intracellular function, but they could be found on the cell surface following tissue injury. The biological function of the translocated DAMPs is still not well known and an efficient delivery of these molecules on the cell surface is required to clarify their biological effects. In this study, we demonstrated that an unclassical secretory signal peptide, N-terminal 18 amino acids of HASPB (HASPB-N18), could efficiently deliver Hsp60, Hsp70, and HMGB1 on the cell surface. Furthermore, the delivery of these molecules on the cell surface by HASPB-N18 is not limited to a special cell line because several cell lines could use this delivery signal to deliver these molecules on the cell surface. Moreover, we demonstrated that Hsp60 on the cell surface delivered by HASPB-N18 could be recognized by a soluble form of LOX-1, which implies that DAMPs on the cell surface delivered by HASPB-N18 have a proper conformation during transport. Therefore, delivery of DAMPs by HASPB-N18 is a reliable model to further understand the biological significance of DAMPs on the cell surface.
Dry friction damping couple at high frequencies
Czech Academy of Sciences Publication Activity Database
Půst, Ladislav; Pešek, Luděk; Košina, Jan; Radolfová, Alena
2014-01-01
Roč. 8, č. 1 (2014), s. 91-100 ISSN 1802-680X Institutional support: RVO:61388998 Keywords : dry friction * damping * high frequencies Subject RIV: BI - Acoustics http://www.kme.zcu.cz/acm/acm/article/view/239/265
Chiral damping of magnetic domain walls
Jué , Emilie; Safeer, C. K.; Drouard, Marc; Lopez, Alexandre; Balint, Paul; Buda-Prejbeanu, Liliana; Boulle, Olivier; Auffret, Stephane; Schuhl, Alain; Manchon, Aurelien; Miron, Ioan Mihai; Gaudin, Gilles
2015-01-01
Structural symmetry breaking in magnetic materials is responsible for the existence of multiferroics1, current-induced spin–orbit torques2, 3, 4, 5, 6, 7 and some topological magnetic structures8, 9, 10, 11, 12. In this Letter we report that the structural inversion asymmetry (SIA) gives rise to a chiral damping mechanism, which is evidenced by measuring the field-driven domain-wall (DW) motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The DW dynamics associated with the chiral damping and those with Dzyaloshinskii–Moriya interaction (DMI) exhibit identical spatial symmetry13, 14, 15, 16, 17, 18, 19. However, both scenarios are differentiated by their time reversal properties: whereas DMI is a conservative effect that can be modelled by an effective field, the chiral damping is purely dissipative and has no influence on the equilibrium magnetic texture. When the DW motion is modulated by an in-plane magnetic field, it reveals the structure of the internal fields experienced by the DWs, allowing one to distinguish the physical mechanism. The chiral damping enriches the spectrum of physical phenomena engendered by the SIA, and is essential for conceiving DW and skyrmion devices owing to its coexistence with DMI (ref. 20).
Piezoelectric RL shunt damping of flexible structures
DEFF Research Database (Denmark)
Høgsberg, Jan Becker; Krenk, Steen
2015-01-01
in the present analysis is based on equal damping of the two modes associated with the resonant vibration form of the structure. An important result of the presented calibration procedure is the explicit inclusion of a quasi-static contribution from the non-resonant vibration modes of the structure via a single...
Stiffness and damping in mechanical design
National Research Council Canada - National Science Library
Rivin, Eugene I
1999-01-01
... important conceptual issues are stiffness of mechanical structures and their components and damping in mechanical systems sensitive to and/or generating vibrations. Stiffness and strength are the most important criteria for many mechanical designs. However, although there are hundreds of books on various aspects of strength, and strength issues ar...
Chiral damping of magnetic domain walls
Jué, Emilie
2015-12-21
Structural symmetry breaking in magnetic materials is responsible for the existence of multiferroics1, current-induced spin–orbit torques2, 3, 4, 5, 6, 7 and some topological magnetic structures8, 9, 10, 11, 12. In this Letter we report that the structural inversion asymmetry (SIA) gives rise to a chiral damping mechanism, which is evidenced by measuring the field-driven domain-wall (DW) motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The DW dynamics associated with the chiral damping and those with Dzyaloshinskii–Moriya interaction (DMI) exhibit identical spatial symmetry13, 14, 15, 16, 17, 18, 19. However, both scenarios are differentiated by their time reversal properties: whereas DMI is a conservative effect that can be modelled by an effective field, the chiral damping is purely dissipative and has no influence on the equilibrium magnetic texture. When the DW motion is modulated by an in-plane magnetic field, it reveals the structure of the internal fields experienced by the DWs, allowing one to distinguish the physical mechanism. The chiral damping enriches the spectrum of physical phenomena engendered by the SIA, and is essential for conceiving DW and skyrmion devices owing to its coexistence with DMI (ref. 20).
Active damping based on decoupled collocated control
Holterman, J.; de Vries, Theodorus J.A.; Auer, Frank; Gardonio, P.; Rafaely, B.
2002-01-01
High-precision machines typically suffer from small but persistent vibrations. As it is difficult to damp these vibrations by passive means, research at the Drebbel Institute at the University of Twente is aimed at the development of an active structural element that can be used for vibration
Kicker for the SLC electron damping ring
International Nuclear Information System (INIS)
Bartelson, L.; Crawford, C.; Dinkel, J.; Kerns, Q.; Howell, J.; Snowdon, S.; Walton, J.
1987-01-01
The SLC electron damping ring requires two kickers each providing a 5 mr kick at 1.2 GEV to pairs of electron bunches spaced 61.63 nsec apart. The exact shape of the kick is unimportant, but the specification applies to the field the bunches see
Damping of liquid sloshing by foams
Sauret, A.; Boulogne, F.; Cappello, J.; Dressaire, E.; Stone, H. A.
2015-02-01
When a container is set in motion, the free surface of the liquid starts to oscillate or slosh. Such effects can be observed when a glass of water is handled carelessly and the fluid sloshes or even spills over the rims of the container. However, beer does not slosh as readily as water, which suggests that foam could be used to damp sloshing. In this work, we study experimentally the effect on sloshing of a liquid foam placed on top of a liquid bath. We generate a monodisperse two-dimensional liquid foam in a rectangular container and track the motion of the foam. The influence of the foam on the sloshing dynamics is experimentally characterized: only a few layers of bubbles are sufficient to significantly damp the oscillations. We rationalize our experimental findings with a model that describes the foam contribution to the damping coefficient through viscous dissipation on the walls of the container. Then we extend our study to confined three-dimensional liquid foam and observe that the behavior of 2D and confined 3D systems are very similar. Thus, we conclude that only the bubbles close to the walls have a significant impact on the dissipation of energy. The possibility to damp liquid sloshing using foam is promising in numerous industrial applications such as the transport of liquefied gas in tankers or for propellants in rocket engines.
Nuclear power plant piping damping parametric effects
International Nuclear Information System (INIS)
Ware, A.G.
1983-01-01
The present NRC guidelines for structural damping to be used in the dynamic stress analyses of nuclear power plant piping systems are generally considered to be overly conservative. As a result, plant designers have in many instances used a considerable number of seismic supports to keep stresses calculated by large scale piping computer codes below the allowable limits. In response to this problem, the NRC and EG and G Idaho are engaged in programs to evaluate piping system damping, in order to provide more realistic and less conservative values to be used in seismic analyses. To generate revised guidelines, solidly based on technical data, new experimental data need to be generated and assessed, and the parameters which influence piping system damping need to be quantitatively identified. This paper presents the current state-of-the-art knowledge in the United States on parameters which influence piping system damping. Examples of inconsistencies in the data and areas of uncertainty are explained. A discussion of programs by EG and G Idaho and other organizations to evaluate various effects is included, and both short and long range goals of the program are outlined
Factors controlling superelastic damping capacity of SMAs
Czech Academy of Sciences Publication Activity Database
Heller, Luděk; Šittner, Petr; Pilch, Jan; Landa, Michal
2009-01-01
Roč. 18, 5-6 (2009), 603-611 ISSN 1059-9495 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z20760514 Keywords : shape memory alloys * superelastic damping * thermomechanical testing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.592, year: 2009
Structural dynamic modification using additive damping
Indian Academy of Sciences (India)
elements, FEM and perturbation methods for reanalysis or structural dynamic modification ... to a system changes its mass, stiffness and damping. Thus ... due to the phase difference between stress ' and strain or 'a И E1 З iE2 for direct strain.
Spatial Damping of Linear Compressional Magnetoacoustic Waves ...
Indian Academy of Sciences (India)
The uncertainty in the radiative relaxation time, how- ever, does .... For spatial damping, we take ω to be real and k to be complex as kR +ikI . The disper- ... bances may travel up in the solar atmosphere through the magnetic field lines that are.
Damping Effects in Aerospace Structures
1979-10-01
Fourier transform of the weighting function h(T) + 00 m -00 Is eaUed the frequency response function. TV« H(u) - j h(T) e"Jwt dr , l... traitement par revitemnt simple a permis une attenuation de Vordre de 3 dB, ramenSc I l’enseflfcle sur la frequence de rotation et de 4 (ffi pour...raidisseurs cir- conf§rentiels et longitudinaux. D’autre part, la masse 3 consacrer au traitement acoustlque est fixge. La question est done posfie
International Nuclear Information System (INIS)
Jones, R.M.; Seidel, M.; Miller, R.H.
1997-05-01
The power spectrum emerging from the damping manifolds of a DDS provides valuable quasi-local information on the displacement of a drive beam from the axis of individual cells, where the displacement may be due to beam offset, small cell misalignment, or a combination of the two. The degree of localization and the indexing of frequency to cell number is determined directly from the spectral function theory. Examples for specific DDS designs will be presented. These relations can be used to determine geometrical misalignment patterns
A review of experimental soil-structure interaction damping
International Nuclear Information System (INIS)
Tsai, N.C.
1981-01-01
In soil-structure interaction analysis, the foundation soil is usually represented by impedance springs and dampers. The impedance damping includes the effect of both the material damping and the radiation damping. Because the impedance theory normally assumes a rigid structural base and an elastic bond between the soil and structure, it is generally held that the radiation damping has been overestimated by the theory. There are some published information on the dynamic tests of footings and structures that allow direct or indirect assessments of the validity of the analytical radiation damping. An overview of such information is presented here. Based on these limited test data, it is concluded that for horizontal soil-structure interaction analysis the analytical radiation damping alone is sufficient to represent the combined material and radiation damping in the field. On the other hand, for vertical analysis it appears that the theory may have overestimated the radiation damping and certain reduction is recommended. (orig.)
Damped time advance methods for particles and EM fields
International Nuclear Information System (INIS)
Friedman, A.; Ambrosiano, J.J.; Boyd, J.K.; Brandon, S.T.; Nielsen, D.E. Jr.; Rambo, P.W.
1990-01-01
Recent developments in the application of damped time advance methods to plasma simulations include the synthesis of implicit and explicit ''adjustably damped'' second order accurate methods for particle motion and electromagnetic field propagation. This paper discusses this method
DEFF Research Database (Denmark)
Li, Hui; Liu, Shengquan; Ji, Haiting
2014-01-01
on the power system stabilizer (PSS) control method. Transient simulation on different damping gain coefficients are conducted for justification. Following the OTEF mechanism analysis, an additional fuzzy damping control strategy with the active/reactive power loop is proposed by identifying the oscillation......This study investigates the inter-area low-frequency damping control strategies of a doubly fed induction generator (DFIG)-based wind farm through oscillation transient energy function (OTEF) analysis. Based on the OTEF descent expressions, the feasibility of damping the inter-area low...... oscillation of the wind turbine shaft. The proposed additional fuzzy control strategy with the active/reactive power loop has better damping performance than the presented PSS control, especially for damping the inter-area low-frequency oscillation....
Onset of chaos in Josephson junctions with intermediate damping
International Nuclear Information System (INIS)
Yao, X.; Wu, J.Z.; Ting, C.S.
1990-01-01
By use of the analytical solution of the Stewart-McCumber equation including quadratic damping and dc bias, the Melnikov method has been extended to the parameter regions of intermediate damping and dc bias for the Josephson junctions with quadratic damping and with linear damping and cosφ term. The comparison between the thresholds predicted by the Melnikov method and that derived from numerical simulation has been studied. In addition, the validity conditions for the Melnikov threshold are also discussed
Tsuzuki, Satori; Yanagisawa, Daichi; Nishinari, Katsuhiro
2018-04-01
This study proposes a model of a totally asymmetric simple exclusion process on a single-channel lane with functions of site assignments along the pit lane. The system model attempts to insert a new particle to the leftmost site at a certain probability by randomly selecting one of the empty sites in the pit lane, and reserving it for the particle. Thereafter, the particle is directed to stop at the site only once during its travel. Recently, the system was determined to show a self-deflection effect, in which the site usage distribution biases spontaneously toward the leftmost site, and the throughput becomes maximum when the site usage distribution is slightly biased to the rightmost site. Our exact analysis describes this deflection effect and show a good agreement with simulations.
DEFF Research Database (Denmark)
Andersen, Kristian
Long-term follow-up on total reconstruction of the temporomandibular joint - functional, psychosocial and radiological assessments in a case-series study......Long-term follow-up on total reconstruction of the temporomandibular joint - functional, psychosocial and radiological assessments in a case-series study...
Chan, Andy C M; Ouyang, Xi H; Jehu, Deborah A M; Chung, Raymond C K; Pang, Marco Y C
2018-01-01
Balance deficits are common after total knee arthroplasty (TKA); however the responsiveness of commonly used balance measurement tools has not been well defined. The objective of this prospective study was to compare the internal and external responsiveness of four measurement tools in assessing recovery of balance function following TKA. A total of 134 individuals with TKA (95 women; age: 66.3±6.6years) completed the Balance Evaluation Systems Test (BESTest), Mini-BESTest, Brief-BESTest, and Berg Balance Scale (BBS) at 2, 4, 8, 12, and 24 weeks post-TKA. The Functional Gait Assessment (FGA) served as the anchor measure, and was also measured across these time points. Internal responsiveness was indicated by the standardized response mean (SRM), while external responsiveness was reflected by the degree of association of the changes of balance scores with those of FGA. The SRM ranged from 0.60-1.14 for the BESTest, 0.40-0.94 for the Mini-BESTest, 0.27-0.91 for the Brief-BESTest, and 0.19-0.70 for the BBS, over time. The change in BESTest and Mini-BESTest scores predicted the change in the FGA scores across all time periods, except for the Mini-BESTest between weeks 12-24, accounting for 13-27%, and 12-24% of the variance, respectively. The Brief-BESTest scores only predicted FGA scores between the weeks 2-4 (R 2 =20%). The changes in BBS scores were not associated with the FGA. The BESTest is the most responsive in measuring recovery of balance among individuals with TKA. The Mini-BESTest is a reasonable option during time constraints. Copyright © 2017. Published by Elsevier B.V.
Seah, R B; Pang, H N; Lo, N N; Chong, H C; Chin, P L; Chia, S L; Yeo, S J
2012-10-01
The success of total knee replacement (TKR) depends on optimal soft-tissue balancing, among many other factors. The objective of this study is to correlate post-operative anteroposterior (AP) translation of a posterior cruciate ligament-retaining TKR with clinical outcome at two years. In total 100 patients were divided into three groups based on their AP translation as measured by the KT-1000 arthrometer. Group 1 patients had AP translation 10 mm. Outcome assessment included range of movement of the knee, the presence of flexion contractures, hyperextension, knee mechanical axes and functional outcome using the Knee Society score, Oxford knee score and the Short-Form 36 questionnaire. At two years, patients in Group 2 reported significantly better Oxford knee scores than the other groups (p = 0.045). A positive correlation between range of movement and AP translation was noted, with patients in group 3 having the greatest range of movement (mean flexion: 117.9° (106° to 130°)) (p 10° (p = 0.01). In this study, the best outcome for cruciate-ligament retaining TKR was achieved in patients with an AP translation of 5 mm to 10 mm.
Preliminary Study on the Damping Effect of a Lateral Damping Buffer under a Debris Flow Load
Directory of Open Access Journals (Sweden)
Zheng Lu
2017-02-01
Full Text Available Simulating the impact of debris flows on structures and exploring the feasibility of applying energy dissipation devices or shock isolators to reduce the damage caused by debris flows can make great contribution to the design of disaster prevention structures. In this paper, we propose a new type of device, a lateral damping buffer, to reduce the vulnerability of building structures to debris flows. This lateral damping buffer has two mechanisms of damage mitigation: when debris flows impact on a building, it acts as a buffer, and when the structure vibrates due to the impact, it acts as a shock absorber, which can reduce the maximum acceleration response and subsequent vibration respectively. To study the effectiveness of such a lateral damping buffer, an impact test is conducted, which mainly involves a lateral damping buffer attached to a two-degree-of-freedom structure under a simulated debris flow load. To enable the numerical study, the equation of motion of the structure along with the lateral damping buffer is derived. A subsequent parametric study is performed to optimize the lateral damping buffer. Finally, a practical design procedure is also provided.
Active and passive damping based on piezoelectric elements -controllability issues-
Holterman, J.; de Vries, Theodorus J.A.; van Amerongen, J.; Jonker, Jan B.; Jonker, J.B.
2001-01-01
Piezoelectric elements are widely used for damping micro-vibrations in mechanical structures. Active damping can be realised robustly by means of collocated actuator-sensor-pairs, controlled so as to extract vibration energy. Excellent damping performance is possible as long as sufficient
Distribution of large-earthquake input energy in viscous damped outrigger structures
Morales Beltran, M.G.; Turan, Gursoy; Yildirim, Umut
2017-01-01
This article provides an analytical framework to assess the distribution of seismic energy in outrigger structures equipped with viscous dampers. The principle of damped outriggers for seismic control applications lies on the assumption that the total earthquake energy will be absorbed by the
The coefficients of the damping in the radioactive fall-out
International Nuclear Information System (INIS)
Stofanova, M.; Usacev, S.
1977-01-01
Radioactive fallout is characterized by time and seasonal variations. So far the independent growth of the 3 H, 90 Sr and 14 C fallout maxima was studied separately. The maxima and minima of the total fallout were compared with that of the above mentioned isotopes. Introducing the damping coefficient for monthly fallout, the seasonal and annual damping coefficients made is possible to determine time difference of the maxima of fallout for the individual components, namely: 3 H, 90 Sr and 14 C. Calculation of these coefficients yielded graphs markedly differentiating the maxima of the gross β activities for the years 1959 to 1973 and the said components of fallout. (author)
On damping of screw dislocation bending vibrations in dissipative crystal: limiting cases
Dezhin, V. V.
2018-03-01
The expression for the generalized susceptibility of the dislocation obtained earlier was used. The electronic drag mechanism of dislocations is considered. The study of small dislocation oscillations was limited. The contribution of the attenuation of low-frequency bending screw dislocation vibrations to the overall coefficient of dynamic dislocation drag in the long-wave and short-wave limits is calculated. The damping of short-wave bending screw dislocation vibrations caused by an external action of an arbitrary frequency has been investigated. The contribution of long-wave bending screw dislocation vibrations damping in the total drag coefficient at an arbitrary frequency is found.
Amplitude damping for single-qubit system with single-qubit mixed-state environment
International Nuclear Information System (INIS)
Jung, Eylee; Hwang, Mi-Ra; Ju, You Hwan; Park, D K; Kim, Hungsoo; Kim, Min-Soo; Son, Jin-Woo
2008-01-01
We study a generalized amplitude damping channel when environment is initially in the single-qubit mixed state. Representing the affine transformation of the generalized amplitude damping by a three-dimensional volume, we plot explicitly the volume occupied by the channels simulatable by a single-qubit mixed-state environment. As expected, this volume is embedded in the total volume by the channels which is simulated by a two-qubit enviroment. The volume ratio is approximately 0.08 which is much smaller than 3/8, the volume ratio for generalized depolarizing channels
International Nuclear Information System (INIS)
Wenz, Frederik; Steinvorth, Sarah; Lohr, Frank; Hacke, Werner; Wannenmacher, Michael
1999-01-01
Purpose: The purpose of this study was to investigate acute normal tissue damage of low irradiation doses to the healthy, adult central nervous system (CNS) using neuropsychological testing of attention functions. Methods and Materials: Neuropsychological testing (IQ, attention [modified Trail-Making Test A, Digit Symbol Test, D2 Test, Wiener Determination Machine]) was used to examine 40 patients (43 ± 10 years) before and immediately after the first fraction (1.2 Gy) of hyperfractionated total body irradiation (TBI) at the University of Heidelberg. The patients received antiemetic premedication. Test results are given as mean percentiles ± standard deviation, with 50 ± 34 being normal. Thirty-eight control patients (53 ± 15 years) were studied to quantify the influence of hospitalization, stress, and repeated testing. Results: The patients showed normal baseline test results (IQ = 101 ± 14, attention = 54 ± 28) and no decrease in test results after 1.2 Gy TBI. Attention functions improved (66 ± 25) corresponding to a practice effect of repeated testing that was seen in the control group, although alternate versions of the tests were used (IQ = 104 ± 10, attention before = 42 ± 29, attention after = 52 ± 31). Conclusion: Our data show no deterioration of neuropsychologic test results acutely after 1.2 Gy whole body exposure in adult patients without CNS disease receiving antiemetic medication
Zinkus, Janis; Mockutė, Lina; Gelmanas, Arūnas; Tamošiūnas, Ramūnas; Vertelis, Arūnas; Macas, Andrius
2017-06-20
BACKGROUND We compared the effects of continuous femoral nerve block (CFNB) and continuous intraarticular block (CIAB) on pain, functional recovery and adverse effects after total knee arthroplasty (TKA). MATERIAL AND METHODS We prospectively randomized 54 patients undergoing TKA into 2 groups: CFNB (Group F) and CIAB (Group I). Surgery was performed under spinal anesthesia. All patients received patient-controlled analgesia (PCA) with morphine, diclofenac, and acetaminophen for the first 72 h postoperatively. Pain was assessed with a visual analog scale (VAS), 48-h morphine consumption and 72-h local anesthetic dosage were recorded, motor blockade was assessed, maximum range of motion (ROM) was measured, and adverse effect profiles were recorded. RESULTS There was no significant difference in postoperative pain at rest, in passive motion, active motion, or active movement (2-min walk test (2MWT)) between study groups. Group I had less opioid usage in the first 24 h postoperatively (p0.05). Significantly lower scores of Bromage scale in Group I in 72 h after surgery (pknee function on day 7 and at 1 month after surgery.
International Nuclear Information System (INIS)
Challa, Vinod R; Prasad, M G; Fisher, Frank T
2009-01-01
Vibration energy harvesting is being pursued as a means to power wireless sensors and ultra-low power autonomous devices. From a design standpoint, matching the electrical damping induced by the energy harvesting mechanism to the mechanical damping in the system is necessary for maximum efficiency. In this work two independent energy harvesting techniques are coupled to provide higher electrical damping within the system. Here the coupled energy harvesting device consists of a primary piezoelectric energy harvesting device to which an electromagnetic component is added to better match the total electrical damping to the mechanical damping in the system. The first coupled device has a resonance frequency of 21.6 Hz and generates a peak power output of ∼332 µW, compared to 257 and 244 µW obtained from the optimized, stand-alone piezoelectric and electromagnetic energy harvesting devices, respectively, resulting in a 30% increase in power output. A theoretical model has been developed which closely agrees with the experimental results. A second coupled device, which utilizes the d 33 piezoelectric mode, shows a 65% increase in power output in comparison to the corresponding stand-alone, single harvesting mode devices. This work illustrates the design considerations and limitations that one must consider to enhance device performance through the coupling of multiple harvesting mechanisms within a single energy harvesting device
Optimizing parameter of particle damping based on Leidenfrost effect of particle flows
Lei, Xiaofei; Wu, Chengjun; Chen, Peng
2018-05-01
Particle damping (PD) has strongly nonlinearity. With sufficiently vigorous vibration conditions, it always plays excellent damping performance and the particles which are filled into cavity are on Leidenfrost state considered in particle flow theory. For investigating the interesting phenomenon, the damping effect of PD on this state is discussed by the developed numerical model which is established based on principle of gas and solid. Furtherly, the numerical model is reformed and applied to study the relationship of Leidenfrost velocity with characteristic parameters of PD such as particle density, diameter, mass packing ratio and diameter-length ratio. The results indicate that particle density and mass packing ratio can drastically improve the damping performance as opposed as particle diameter and diameter-length ratio, mass packing ratio and diameter-length ratio can low the excited intensity for Leidenfrost state. For discussing the application of the phenomenon in engineering, bound optimization by quadratic approximation (BOBYQA) method is employed to optimize mass packing ratio of PD for minimize maximum amplitude (MMA) and minimize total vibration level (MTVL). It is noted that the particle damping can drastically reduce the vibrating amplitude for MMA as Leidenfrost velocity equal to the vibrating velocity relative to maximum vibration amplitude. For MTVL, larger mass packing ratio is best option because particles at relatively wide frequency range is adjacent to Leidenfrost state.
Directory of Open Access Journals (Sweden)
Paul Baker
Full Text Available BACKGROUND: The number of patients presenting for total knee replacement who are classified as obese is increasing. The functional benefits of performing TKR in these patients are unclear. AIM: To assess the influence pre-operative body mass index has upon knee specific function, general health status and patient satisfaction at 3 years following total knee replacement. DESIGN: Retrospective comparative cohort study using prospectively collected data from an institutional arthroplasty register. METHODS: 1367 patients were assessed using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC and Medical Outcomes Trust Short Form-36 (SF-36 scores supplemented by a validated measure of satisfaction pre-operatively and subsequently at 1,2 and 3 year post-operatively. Comparisons were made by dividing the cohort into 4 groups based on body mass index (BMI 18.5-25.0 kg/m(2 (n = 253;>25.0-30.0 kg/m(2 (n = 559;>30.0-35.0 kg/m(2 (n = 373;>35.0 kg/m(2 (n = 182. RESULTS: Despite lower pre-operative, 1 and 3 year WOMAC and SF-36 scores patients with the highest BMIs >35.0 kg/m(2 experienced similar improvements to patients with a 'normal' BMI (18.5-25.0 kg/m(2 at 1 year (Difference in WOMAC improvement = 0.0 (95%CI -5.2 to 5.2, p = 1.00 and this improvement was sustained at up to 3 years (Difference in 1 year to 3 year improvement = 2.2 (95%CI: -2.1 to 6.5, p = 1.00. This effect was also observed for the SF-36 mental and physical component scores. Despite equivalent functional improvements levels of satisfaction in the >35.0 kg/m(2 group were lower than for any other BMI group (>35.0 kg/m(2 = 84.6% satisfied versus 18.5-5.0 kg/m(2 = 93.3% satisfied,p = 0.01 as was the proportion of patients who stated they would have the operation again (>35.0 kg/m(2 = 69.6% versus 18.5-25.0 kg/m(2 = 82.2%,p = 0.01. CONCLUSION: Obese and morbidly obese patients gain as much functional benefit from
Robust Design of LCL-Filters for Active Damping in Grid Converters
DEFF Research Database (Denmark)
Alzola, Rafael Pena; Liserre, Marco; Blaabjerg, Frede
2013-01-01
Grid converters require a simple inductor or an LCL-filter to limit the current ripples. The LCL-filter is nowadays the preferred solution as it allows lower inductance values. In order to solve the stability concerns, active damping is preferred to passive damping since it does not use dissipative...... elements. However, large variations in the grid inductance and resonances arising from parallel converters may still compromise the system stability. This calls for a robust design of LCL-filters with active damping. This paper proposes a design flow with little iteration for two well-known methods, namely...... lead-lag network and current capacitor feedback. The proposed formulas for the resonance frequency, grid and converter inductance ratio, and capacitance of the LCL-filter allow calculating all the LCL-filter parameters. An estimation for the achieved Total Harmonic Distortion (THD) of the grid current...
Calculating latent frequencies of systems with local damping
International Nuclear Information System (INIS)
Kolonits, Ferenc
2005-01-01
Modal analysis of damped systems often cannot proceed with common real-eigenvalue techniques. The system of equilibrium equations leads to a matrix with elements being quadratic functions of a parameter λ. The values of that which make the matrix singular are the latent roots, while the solutions of the associated homogenous equation are the latent vectors. They are the (generally complex) characteristic frequencies and the mode shapes of the system, respectively. Although the theory is well developed, the numerical application is open to refinements yet. A reduction to better-known real-domain subtasks deserves attention. With a theorem of Popper and Gaspar, a n x n λ-matrix problem can be cut in two: into n-size asymmetric real matrices having as eigenvalues the n lower and n upper latent roots, ranked by absolute value. This approach may be of use for systems with high number of degrees of freedom while damped by a relatively few concentrated devices. It might fit also an earthquake analysis, where the lower portion of eigenvalues is customarily what counts. The dampers appear in the splitting algorithm as restricted-size modifications, ready for use by the Sherman-Morrison-Woodbury identity. The task is re-traced this way to a more usual real-asymmetric eigenproblem. A requirement of convergence is that the lower and upper n-set of latent values must be distinct. With odd-number degrees of freedom and neither over-damped, i.e. all latent roots being complex, this condition is surely violated. For such cases, a supplemental algorithm is proposed
Readout Electronics for BGO Calorimeter of DAMPE: Status during the First Half-year after Launching
Ma, Siyuan; Feng, Changqing; Zhang, Deliang; Wang, Qi
2016-07-01
The DAMPE (DArk Matter Particle Explorer) is a scientic satellite which was successfully launched into a 500 Km sun-synchronous orbit, on December 17th, 2015, from the Jiuquan Satellite Launch Center of China. The major scientific objective of DAMPE mission is indirect searching for dark matter by observing high energy primary cosmic rays, especially positrons/electrons and gamma rays with an energy range from 5 GeV to 10 TeV. The BGO (Bismuth Germanate Oxide) calorimeter, which is a critical sub-detector of DAMPE payload, was developed for measuring the energy of cosmic particles, distinguishing positrons/electrons and gamma rays from hadron background, and providing trigger information. It is composed of 308 BGO crystal logs, with the size of 2.5cm*2.5cm*60cm for each log to form a total absorption electromagnetic calorimeter. All the BGO logs are stacked in 14 layers, with each layer consisting of 22 BGO crystal logs and each log is viewed by two Hamamatsu R5610A PMTs (photomultiplier tubes), from both sides respectively. Each PMT incorporates a three dynode pick off to achieve a large dynamic range, which results in 616 PMTs and 1848 signal channels. The main function of readout electronics system, which consists of 16 FEE(Front End Electronics) modules, is to precisely measure the charge of PMT signals and providing "hit" signals. The hit signals are sent to the trigger module of PDPU (Payload Data Process Unit) to generate triggers for the payload. The calibration of the BGO calorimeter is composed of pedestal testing and electronic linear scale, which are executed frequently in the space after launching. The data of the testing is transmitted to ground station in the form of scientific data. The monitor status consists of temperature, current and status words of the FEE, which are measured and recorded every 16 seconds and packed in the engineering data, then transmitted to ground station. The status of the BGO calorimeter can be evaluated by the calibration
Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Abrahamson, Norman; Campbell, Kenneth; Silva, Walter
2014-01-01
Ground motion prediction equations (GMPEs) for elastic response spectra are typically developed at a 5% viscous damping ratio. In reality, however, structural and nonstructural systems can have other damping ratios. This paper develops a new model for a damping scaling factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE for damping ratios between 0.5% to 30%. The model is developed based on empirical data from worldwide shallow crustal earthquakes in active tectonic regions. Dependencies of the DSF on potential predictor variables, such as the damping ratio, spectral period, ground motion duration, moment magnitude, source-to-site distance, and site conditions, are examined. The strong influence of duration is captured by the inclusion of both magnitude and distance in the DSF model. Site conditions show weak influence on the DSF. The proposed damping scaling model provides functional forms for the median and logarithmic standard deviation of DSF, and is developed for both RotD50 and GMRotI50 horizontal components. A follow-up paper develops a DSF model for vertical ground motion.
Damping Estimation of Friction Systems in Random Vibrations
DEFF Research Database (Denmark)
Friis, Tobias; Katsanos, Evangelos; Amador, Sandro
Friction is one of the most efficient and economical mechanisms to reduce vibrations in structural mechanics. However, the estimation of the equivalent linear damping of the friction damped systems in experimental modal analysis and operational modal analysis can be adversely affected by several...... assumptions regarding the definition of the linear damping and the identification methods or may be lacking a meaningful interpretation of the damping. Along these lines, this project focuses on assessing the potential to estimate efficiently the equivalent linear damping of friction systems in random...
Enhanced damping for bridge cables using a self-sensing MR damper
Chen, Z. H.; Lam, K. H.; Ni, Y. Q.
2016-08-01
This paper investigates enhanced damping for protecting bridge stay cables from excessive vibration using a newly developed self-sensing magnetorheological (MR) damper. The semi-active control strategy for effectively operating the self-sensing MR damper is formulated based on the linear-quadratic-Gaussian (LQG) control by further considering a collocated control configuration, limited measurements and nonlinear damper dynamics. Due to its attractive feature of sensing-while-damping, the self-sensing MR damper facilitates the collocated control. On the other hand, only the sensor measurements from the self-sensing device are employed in the feedback control. The nonlinear dynamics of the self-sensing MR damper, represented by a validated Bayesian NARX network technique, are further accommodated in the control formulation to compensate for its nonlinearities. Numerical and experimental investigations are conducted on stay cables equipped with the self-sensing MR damper operated in passive and semi-active control modes. The results verify that the collocated self-sensing MR damper facilitates smart damping for inclined cables employing energy-dissipative LQG control with only force and displacement measurements at the damper. It is also demonstrated that the synthesis of nonlinear damper dynamics in the LQG control enhances damping force tracking efficiently, explores the features of the self-sensing MR damper, and achieves better control performance over the passive MR damping control and the Heaviside step function-based LQG control that ignores the damper dynamics.
Extracellular ATP acts as a damage associated molecular pattern (DAMP signal in plants
Directory of Open Access Journals (Sweden)
Kiwamu eTanaka
2014-09-01
Full Text Available As sessile organisms, plants have evolved effective mechanisms to protect themselves from environmental stresses. Damaged (i.e., wounded plants recognize a variety of endogenous molecules as danger signals, referred to as damage-associated molecular patterns (DAMPs. ATP is among the molecules that are released by cell damage, and recent evidence suggests that ATP can serve as a DAMP. Although little studied in plants, extracellular ATP is well known for its signaling role in animals, including acting as a DAMP during the inflammatory response and wound healing. If ATP acts outside the cell, then it is reasonable to expect that it is recognized by a plasma membrane-localized receptor. Recently, DORN1, a lectin receptor kinase, was shown to recognize extracellular ATP in Arabidopsis. DORN1 is the founding member of a new purinoceptor subfamily, P2K (P2 receptor Kinase, which is plant-specific. P2K1 (DORN1 is required for ATP-induced cellular responses (e.g., cytosolic Ca2+ elevation, MAPK phosphorylation, and gene expression. Genetic analysis of loss-of-function mutants and overexpression lines showed that P2K1 participates in the plant wound response, consistent with the role of ATP as a DAMP. In this review, we summarize past research on the roles and mechanisms of extracellular ATP signaling in plants, and discuss the direction of the future research of extracellular ATP as a DAMP signal.
DAMPING OF SUBSYNCHRONOUS MODES OF OSCILLATIONS
Directory of Open Access Journals (Sweden)
JAGADEESH PASUPULETI
2006-06-01
Full Text Available The IEEE bench mark model 2 series compensated system is considered for analysis. It consists of single machine supplying power to infinite bus through two parallel lines one of which is series compensated. The mechanical system considered consists of six mass, viz, high pressure turbine, intermediate pressure turbine, two low pressure turbines, generator and an exciter. The excitation system considered is IEEE type 1 with saturation. The auxiliary controls considered to damp the unstable subsynchronous modes of oscillations are Power System Stabilizer (PSS and Static var Compensator (SVC. The different cases of power system stabilizer and reactive power controls are adapted to study the effectiveness of damping these unstable subsynchronous modes of oscillations.
Damping of Crank–Nicolson error oscillations
DEFF Research Database (Denmark)
Britz, Dieter; Østerby, Ole; Strutwolf, J.
2003-01-01
The Crank–Nicolson (CN) simulation method has an oscillatory response to sharp initial transients. The technique is convenient but the oscillations make it less popular. Several ways of damping the oscillations in two types of electrochemical computations are investigated. For a simple one......-dimensional system with an initial singularity, subdivision of the first time interval into a number of equal subintervals (the Pearson method) works rather well, and so does division with exponentially increasing subintervals, where however an optimum expansion parameter must be found. This method can...... be computationally more expensive with some systems. The simple device of starting with one backward implicit (BI, or Laasonen) step does damp the oscillations, but not always sufficiently. For electrochemical microdisk simulations which are two-dimensional in space and using CN, the use of a first BI step is much...
Relativity damps OPEP in nuclear matter
International Nuclear Information System (INIS)
Banerjee, M.K.
1998-06-01
Using a relativistic Dirac-Brueckner analysis the OPEP contribution to the ground state energy of nuclear matter is studied. In the study the pion is derivative-coupled. The author finds that the role of the tensor force in the saturation mechanism is substantially reduced compared to its dominant role in a usual nonrelativistic treatment. He shows that the damping of derivative-coupled OPEP is actually due to the decrease of M * /M with increasing density. He points out that if derivative-coupled OPEP is the preferred form of nuclear effective lagrangian nonrelativistic treatment of nuclear matter is in trouble. Lacking the notion of M * it cannot replicate the damping. He suggests an examination of the feasibility of using pseudoscalar coupled πN interaction before reaching a final conclusion about nonrelativistic treatment of nuclear matter
Damping system immersed in a fluid
International Nuclear Information System (INIS)
1980-01-01
The invention relates to a damping system which is immersed in a fluid and allows slow motion, while opposing fast motion of a mobile or deformable system immersed in a fluid. Nuclear reactors utilize fabricated assemblies immmersed in the spent fuel storage pool to support the fuel elements placed in the pool, e.g., when refueling the reactor. These fabricated assemblies must be held in position, relative to the concrete walls of the pool, so as to allow slow deformation of the assemblies due to thermal expansion, while curbing fast motion, e.g., earthquake-induced motion. Such fast motion due to earthquakes might be the cause of resonance phenomena involving the fuel storage rack structure and the pool walls, should the rack structure and pool walls have the same resonant frequency. In the event of an earthquake, the damping system would provide for fast curbing of structure motion to prevent uncontrolled deformation which might result in breaks and destruction [fr
WAKEFIELD DAMPING FOR THE CLIC CRAB CAVITY
Ambattu, P; Dexter, A; Carter, R; Khan, V; Jones, R; Dolgashev, V
2009-01-01
A crab cavity is required in the CLIC to allow effective head-on collision of bunches at the IP. A high operating frequency is preferred as the deflection voltage required for a given rotation angle and the RF phase tolerance for a crab cavity are inversely proportional to the operating frequency. The short bunch spacing of the CLIC scheme and the high sensitivity of the crab cavity to dipole kicks demand very high damping of the inter-bunch wakes, the major contributor to the luminosity loss of colliding bunches. This paper investigates the nature of the wakefields in the CLIC crab cavity and the possibility of using various damping schemes to suppress them effectively.
System Reduction and Damping of Flexible Structures
DEFF Research Database (Denmark)
Høgsberg, Jan Riess; Krenk, Steen
2007-01-01
An increasing number of flexible structures such as cable-stayed bridges, pedestrian bridges and high-rise buildings are fitted with local dampers to mitigate vibration problems. In principle the effect of local dampers can be analyzed by use of complex modes, e.g. in conjunction with an averaging...... technique for local linearization of the damper characteristics. However, the complex mode shapes and frequencies depend on the magnitude of the damper and therefore are less suitable for design of the damper system. An efficient alternative consists in the use of a two-component representation...... of the damped modes of the structure. The idea is to represent the damped mode as a linear combination of the modes that occur in two distinctly different situations representing extreme conditions: the mode shape of the structure without the damper(s), and the mode shape of the structure, when the damper...
Size effect related to damping caused by water submersion
International Nuclear Information System (INIS)
Dong, R.G.
1981-01-01
An important effect of water submersion on the dynamic response of a structure is the increase in effective damping. The dynamic response of submerged structures is of interest in the nuclear power industry for reasons of operational safety during seismic and other dynamic excitations. In this paper, the added damping contribution that results from the viscosity of water and the dependence of the contribution on structural size are examined. Other factors considered are the applicable range of viscous damping with respect to displacement amplitude and, as far as damping is concerned, how far neighboring members must be from each other to respond as if in open water. An expression is derived for relating the damping value to structural size. Estimated added-damping values for representative fuel elements, fuel bundles, and main steam-pressure-relief-valve lines are given based on our derived expression for added damping
Single bunch beam breakup in linacs and BNS damping
International Nuclear Information System (INIS)
Toyomasu, Takanori
1991-12-01
We study a single-bunch beam breakup (BBU) problem by a macro-particle model. We consider both the BBU solution and the Landau damping solution which includes the Balakin-Novokhatsky-Smirnov (BNS) damping. In the BBU solution, we get an analytic solution which includes both the Chao-Richter-Yao solution and the two-particle model solution and which agrees well with simulation. The solution can also be used in a multi-bunch case. In the Landau damping solution, we can be see the mechanism of Landau damping formally and can get some insights into BNS damping. We confirm that a two-particle model criterion for BNS damping is a good one. We expect that the two-particle model criterion is represented by the first order interaction in Landau damping solution of a macro-particle model. (author)
A review of damping of two-phase flows
International Nuclear Information System (INIS)
Hara, Fumio
1993-01-01
Damping of two-phase flows has been recognized as one of the most unknown parameters in analyzing vibrational characteristics of structures subjected to two-phase flows since it seems to be influenced by many physical parameters involved in the physics of dynamic energy dissipation of a vibrating structure, for example, liquid viscosity, surface tension, flow velocity, mass ratio, frequency, void fraction, flow regime and so forth. This paper deals with a review of scientific works done to date on the damping of two phase flows and discussions about what has been clarified and what has not been known to us, or what kinds of research are needed about two-phase flow damping. The emphasis is put on the definition of two-phase fluid damping, damping measurement techniques, damping characteristics in relation to two phase flow configurations, and damping generation mechanisms
Power Oscillations Damping in DC Microgrids
DEFF Research Database (Denmark)
Hamzeh, Mohsen; Ghafouri, Mohsen; Karimi, Houshang
2016-01-01
This paper proposes a new control strategy for damping of power oscillations in a multi-source dc microgrid. A parallel combination of a fuel cell (FC), a photovoltaic (PV) system and a supercapacitor (SC) are used as a hybrid power conversion system (HPCS). The SC compensates for the slow transi...... of the proposed control scheme is verified using hardware-in-the-loop (HIL) simulations carried out in OPAL-RT technologies....
Multibunch resistive wall instability damping with feedback
International Nuclear Information System (INIS)
Zhabitskij, V.M.; Korenev, I.L.; Yudin, L.A.
1992-01-01
The theory of multibunch transverse resistive wall instability damping with feedback is development. The system of coupling equations is obtained for description of bunched beam motion. The general solution and eigen frequencies are found. But for two bunches or multi bunches the tune splitting is found. The band of the tune splitting is calculated. The influence of the tune splitting on the damper system stability is discussed. 14 refs
The Frequency and Damping of Soil-Structure Systems with Embedded Foundation
International Nuclear Information System (INIS)
Ghannad, M. Ali; Rahmani, Mohammad T.; Jahankhah, Hossein
2008-01-01
The effect of foundation embedment on fundamental period and damping of buildings has been the title of several researches in three past decades. A review of the literature reveals some discrepancies between proposed formulations for dynamic characteristics of soil-embedded foundation-structure systems that raise the necessity of more investigation on this issue. Here, first a set of approximate polynomial equations for soil impedances, based on numerical data calculated from well known cone models, are presented. Then a simplified approach is suggested to calculate period and damping of the whole system considering soil medium as a viscoelastic half space. The procedure includes both material and radiation damping while frequency dependency of soil impedance functions is not ignored. Results show that soil-structure interaction can highly affect dynamic properties of system. Finally the results are compared with one of the commonly referred researches
On the origin of nonlocal damping in plasmonic monomers and dimers
DEFF Research Database (Denmark)
Tserkezis, Christos; Yan, Wei; Hsieh, Wenting
2017-01-01
The origin and importance of nonlocal damping is discussed through simulations with the generalized nonlocal optical response (GNOR) theory, in conjunction with time-dependent density functional theory (TDDFT) calculations and equivalent circuit modeling, for some of the most typical plasmonic...... architectures: metalâ€“dielectric interfaces, metalâ€“dielectricâ€“metal gaps, spherical nanoparticles and nanoparticle dimers. It is shown that diffusive damping, as introduced by the convectiveâ€“diffusive GNOR theory, describes well the enhanced losses and plasmon broadening predicted by ab initio...... the interface. Diffusive nonlocal theories provide therefore an efficient means to tackle plasmon damping when electron tunneling can be safely disregarded, without the need to resort to more accurate, but time-consuming fully quantum-mechanical studies....
Clustering of galaxies near damped Lyman-alpha systems with (z) = 2.6
Wolfe, A. M
1993-01-01
The galaxy two-point correlation function, xi, at (z) = 2.6 is determined by comparing the number of Ly-alpha-emitting galaxies in narrowband CCD fields selected for the presence of damped L-alpha absorption to their number in randomly selected control fields. Comparisons between the presented determination of (xi), a density-weighted volume average of xi, and model predictions for (xi) at large redshifts show that models in which the clustering pattern is fixed in proper coordinates are highly unlikely, while better agreement is obtained if the clustering pattern is fixed in comoving coordinates. Therefore, clustering of Ly-alpha-emitting galaxies around damped Ly-alpha systems at large redshifts is strong. It is concluded that the faint blue galaxies are drawn from a parent population different from normal galaxies, the presumed offspring of damped Ly-alpha systems.
Damping by heat conduction in the Timoshenko system: Fourier and Cattaneo are the same
Said-Houari, Belkacem
2013-08-01
We consider the Cauchy problem for the one-dimensional Timoshenko system coupled with heat conduction, wherein the latter is described by either the Cattaneo law or the Fourier law. We prove that heat dissipation alone is sufficient to stabilize the system in both cases, so that additional mechanical damping is unnecessary. However, the decay of solutions without the mechanical damping is found to be slower than that with mechanical damping. Furthermore, in contrast to earlier results of Said-Houari and Kasimov (2012) [10] and Fernández Sare and Racke (2009) [12], we find that the Timoshenko-Fourier and the Timoshenko-Cattaneo systems have the same decay rate. The rate depends on a certain number α (first identified by Santos et al., 2012 [11] in a related study in a bounded domain), which is a function of the parameters of the system. © 2013 Elsevier Inc.
Identification of weak nonlinearities on damping and stiffness by the continuous wavelet transform
Ta, Minh-Nghi; Lardiès, Joseph
2006-05-01
We consider the free response of a nonlinear vibrating system. Using the ridges and skeletons of the continuous wavelet transform, we identify weak nonlinearities on damping and stiffness and estimate their physical parameters. The crucial choice of the son wavelet function is obtained using an optimization technique based on the entropy of the continuous wavelet transform. The method is applied to simulated single-degree-of-freedom systems and multi-degree-of-freedom systems with nonlinearities on damping and stiffness. Experimental validation of the nonlinear identification and parameter estimation method is presented. The experimental system is a clamped beam with nonlinearities on damping and stiffness and these nonlinearities are identified and quantified from a displacement sensor.
Operation and performance of the PEP-II prototype longitudinal damping system at ALS
International Nuclear Information System (INIS)
Teytelman, D.; Claus, R.; Fox, J.
1995-05-01
A modular programmable longitudinal feedback system has been developed as a component of the PEP-II R+D program. This system is based on a family of VME and VXI packaged signal processing functions which implement a general purpose digital feedback controller for accelerators with bunch spacings of 2 ns. A complete PEP-II prototype system has been configured and installed for use at the LBL Advanced Light Source. The system configuration used for tests at the ALS is described and results are presented showing the action of the feedback system. Open and closed loop results showing the detection and calculation of feedback signals from bunch motion are presented and the system is shown to damp coupled-bunch instabilities in the ALS. Use of the system for accelerator diagnostics is illustrated via measurement of grow-damp transients which quantify growth rates without feedback, damping rates with feedback, and identify unstable modes
Metallic materials for mechanical damping capacity applications
Crăciun, R. C.; Stanciu, S.; Cimpoeșu, R.; (Dragoș Ursanu, A. I.; Manole, V.; Paraschiv, P.; Chicet, D. L.
2016-08-01
Some metallic materials exhibit good damping capacity of mechanical energy into thermal energy. This property along with the others metallic characteristics make this materials interesting for a big number of applications. These materials can be used as bumpers in different applications including automotive field. Beside grey cast iron and shape memory alloys few new metallic materials are presented for the supposition of high damping capacity. We analyze the causes that increase the internal friction of some metallic materials and possibilities to enhance this property through different mechanical, physical or chemical methods. Shape memory alloys, especially those based on copper, present a different damping capacity on martensite, austenite or transition state. In the transformation range M ↔A, which in case of copper base shape memory alloys is quite large, the metallic intelligent materials present a high internal friction, almost comparable with natural rubber behavior that can transform mechanical energy into thermal energy till a certain value of the external solicitation. These materials can be used as noise or small vibrations bumpers or even as shock absorbers in automotive industry.
Limitations of modal analysis of damped structures
International Nuclear Information System (INIS)
Krapf, K.G.; Woelfel, H.
1983-01-01
Quite recently discrete spring-damper elements are increasingly used for the low-tuned supports of nuclear power-plant buildings and equipment (reactor building, turbine-fundaments etc.) to reduce the vibration response due to the dynamic load cases earthquake and airplane crash. Because of this development, it is to be investigated whether the usual modal analysis method is applicable within the design process or should be changed respectively replaced in special cases. The paper contributes to this discussion by demonstrating and valuing the discrepancies in the different ways for the implementation of damping. Different methods for uncoupling (energy weighting, reduction to Rayleigh-damping) are compared with the solution of the coupled equations of motion. In particular vertical vibrations of a spring-damper-supported building on foundation (including ground springs) are examined using a two-degree-of-freedom-system. The results of coupled and (by force) uncoupled methods are interpreted concerning free vibration by comparison of the damping of natural vibrations, natural frequencies and natural mode shapes. The effect on the forced vibrations is shown by floor response spectra to an earthquake accelerogram. (orig./HP)
First Results from the DAMPE Mission
CERN. Geneva
2018-01-01
DAMPE (DArk Matter Particle Explorer) is a satellite mission of the Chinese Academy of Sciences (CAS) dedicated to high energy cosmic ray detections. Since its successful launch on December 17th, 2015 a large amount of cosmic ray data has been collected. With relatively large acceptance, DAMPE is designed to detect electrons (and positrons) up to 10 TeV with unprecedented energy resolution to search for new features in the cosmic ray electron plus positron (CRE) spectrum. It will also study cosmic ray nuclei up to 100 TeV with good precision, which will bring new input to the study of their still unknown origin and their propagation through the Galaxy. In this talk, the DAMPE mission will be introduced, together with some details of the construction and on-ground calibration of the detector subsystems. The in-orbit detector commissioning, calibration and operation will be described. First data analysis results, including the recently published CRE spectrum from 25 GeV to 4.6 TeV based on the data collected i...
DAMPs and influenza virus infection in ageing.
Samy, Ramar Perumal; Lim, Lina H K
2015-11-01
Influenza A virus (IAV) is a serious global health problem worldwide due to frequent and severe outbreaks. IAV causes significant morbidity and mortality in the elderly population, due to the ineffectiveness of the vaccine and the alteration of T cell immunity with ageing. The cellular and molecular link between ageing and virus infection is unclear and it is possible that damage associated molecular patterns (DAMPs) may play a role in the raised severity and susceptibility of virus infections in the elderly. DAMPs which are released from damaged cells following activation, injury or cell death can activate the immune response through the stimulation of the inflammasome through several types of receptors found on the plasma membrane, inside endosomes after endocytosis as well as in the cytosol. In this review, the detriment in the immune system during ageing and the links between influenza virus infection and ageing will be discussed. In addition, the role of DAMPs such as HMGB1 and S100/Annexin in ageing, and the enhanced morbidity and mortality to severe influenza infection in ageing will be highlighted. Copyright © 2015 Elsevier B.V. All rights reserved.
Possibility of Landau damping of gravitational waves
International Nuclear Information System (INIS)
Gayer, S.; Kennel, C.F.
1979-01-01
There is considerable uncertainty in the literature concerning whether or not transverse traceless gravitational waves can Landau damp. Physically, the issue is whether particles of nonzero mass can comove with surfaces of constant wave phase, and therefore, loosely, whether gravitational waves can have phase speeds less than that of light. We approach the question of Landau damping in various ways. We consider first the propagation of small-amplitude gravitational waves in an ideal fluid-filled Robertson-Walker universe of zero spatial curvature. We argue that the principle of equivalence requires those modes to be lightlike. We show that a freely moving particle interacting only with the collective fields cannot comove with such waves if it has nonzero mass. The equation for gravitational waves in collisionless kinetic gases differs from that for fluid media only by terms so small that deviations from lightlike propagation are unmeasurable. Thus, we conclude that Landau damping of small-amplitude, transverse traceless gravitational waves is not possible
Radiative damping in plasma-based accelerators
Directory of Open Access Journals (Sweden)
I. Yu. Kostyukov
2012-11-01
Full Text Available The electrons accelerated in a plasma-based accelerator undergo betatron oscillations and emit synchrotron radiation. The energy loss to synchrotron radiation may seriously affect electron acceleration. The electron dynamics under combined influence of the constant accelerating force and the classical radiation reaction force is studied. It is shown that electron acceleration cannot be limited by radiation reaction. If initially the accelerating force was stronger than the radiation reaction force, then the electron acceleration is unlimited. Otherwise the electron is decelerated by radiative damping up to a certain instant of time and then accelerated without limits. It is shown that regardless of the initial conditions the infinite-time asymptotic behavior of an electron is governed by a self-similar solution providing that the radiative damping becomes exactly equal to 2/3 of the accelerating force. The relative energy spread induced by the radiative damping decreases with time in the infinite-time limit. The multistage schemes operating in the asymptotic acceleration regime when electron dynamics is determined by the radiation reaction are discussed.
Directory of Open Access Journals (Sweden)
Abbas AbdulMajeed Allawi
2016-06-01
Full Text Available This paper studies the combination fluid viscous dampers in the outrigger system to add supplementary damping into the structure, which purpose to remove the dependability of the structure to lower variable intrinsic damping. It works by connecting the central core, comprising either shear walls or braced frames, to the outer perimeter columns. The modal considered is a 36 storey square high rise reinforced concrete building. By constructing a discrete lumped mass model, and using frequency-based response function, two systems of dampers, parallel and series systems are studied. The maximum lateral load at the top of the building is calculated, and this load will be applied at every floor of the building, giving a conservative solution. For static study Equivalent Lateral Force (ELF was conducted. MATLAB software, has been used in this study. From analysis data, it is observed that the parallel system of dampers result lower amplitude of vibration and achieved more efficiently compared to the series system, and the horizontal displacement for each configurations by using MATLAB software is less than the analytical solution using a uniformly distributed load of 36 nodal point forces that divided the total height.
Huh, In Young; Kim, Dae-Young; Lee, Ji-Hyeon; Shin, Soo Jin; Cho, Young Woo; Park, Soon Eun
2012-02-01
Tourniquets are used to provide a bloodless surgical field for extremities. Hypotension due to vasodilation and bleeding after tourniquet deflation is a common event. Hemodynamic stability is modulated by the autonomic nervous system (ANS). Heart rate variability (HRV) is a sensitive method for detecting individuals who may be at risk of hemodynamic instability during general anesthesia. The purpose of this study was to investigate ANS function to predict hypotension after tourniquet deflation. Eighty-six patients who underwent total knee replacement arthroplasty (TKRA) were studied. HRV, systolic blood pressure variability (SBPV) and baroreflex sensitivity (BRS) were analyzed. We assigned two groups depending on the lowest systolic blood pressure (SBP) or mean BP (MBP) after tourniquet release (Group H; SBP 80 mmHg and MBP > 60 mmHg). Fifteen patients developed severe hypotension and ten patients were treated with ephedrine. Of the parameters of HRV, SBPV, and BRS, only BRS(SEQ) was significant being low in Group H. BRS and high-frequency SBPV were correlated with the degree of MBP change after tourniquet deflation. Preoperative low BRS is associated with hypotension after tourniquet deflation, suggesting the importance of baroreflex regulation for intraoperative hemodynamic stability.
Zhou, Zhou; Lin, Jinpiao; Huo, Rongfen; Huang, Wenkang; Zhang, Jian; Wang, Li; Sun, Yue; Shen, Baihua; Li, Ningli
2012-11-01
It is well known that dendritic cells (DCs) play a critical role in the initiation and development of an immune response. Inhibitory effect on DC maturation alters immune-mediated inflammatory reaction in vivo. Total glucosides of paeony (TGP) are active compounds extracted from the roots of Paeonia lactiflora and have been widely used to ameliorate inflammation in therapy for autoimmune diseases. However, whether TGP act on DC maturation remains unknown. In this study, we investigated the effect of TGP on DC maturation in ovalbumin (OVA) immunized mice. Ear inflammation was inhibited by TGP (150 mgkg(-1), i.p.×11 days) obviously. The antigen presenting capacity of DC derived from TGP-treated mice was arrested. Meanwhile, OVA specific T cell proliferation was inhibited. In addition, we found that maturation of DCs was decreased by TGP treatment. Furthermore, OVA specific T cell proliferation was rescued by the adoptive transfer of mature DCs (mDCs) into TGP treated OVA-challenged mice. The research on the mechanism showed that TGP significantly inhibited activation of TLR4/5 singling. All these results demonstrated that TGP inhibited DC maturation and function by selectively blocking TLR4/5 activation in vivo, which in turn leads to reduce immune-mediated inflammation in vivo, adding a novel mechanism and therapeutic target of TGP for inflammatory and autoimmune disease treatment. Copyright © 2012 Elsevier B.V. All rights reserved.
Senioris, Antoine; Saffarini, Mo; Rahali, Said; Malekpour, Louis; Dujardin, Franck; Courage, Olivier
2016-08-01
Anterior knee pain (AKP) is observed in total knee arthroplasty (TKA) both with and without patellar resurfacing, and neither patellar denervation nor secondary resurfacing are effective for treating the symptoms. The exact causes for pain remain unclear, though abnormal patellofemoral forces due to patellar malalignment or inadequate implant design can play an important role. The purpose of this study was to arthroscopically evaluate patellofemoral congruence after wound closure following TKA without patellar resurfacing and correlate it to patellar morphology and postoperative pain and function. The authors prospectively studied 30 patients that received uncemented mobile-bearing TKA. Patellofemoral congruence was assessed arthroscopically after wound closure by estimating the contact area between the native patella and the prosthetic trochlea (> two-thirds, > one-third, congruence was correlated with patellar morphology (Pcongruence and patient characteristics. While patellar morphology and patellofemoral congruence are strongly related, they are not associated with clinical outcomes or patient demographics. Considering that numerous incongruent patellofemoral joints were pain-free, and conversely, many perfectly congruent patellofemoral joints had anterior pain, the authors suppose that pain is probably caused by mechanisms other than patellofemoral pressures.
International Nuclear Information System (INIS)
Leiper, A.D.; Stanhope, R.; Lau, T.; Grant, D.B.; Blacklock, H.; Chessells, J.M.; Plowman, P.N.
1987-01-01
Seventeen children with acute leukaemia and myeloproliferative disorders were investigated for growth and endocrine dysfunction. All had undergone bone marrow transplantation prepared with cyclophosphamide and single fraction total body irradiation (900-1000 cGy) between 1.5 and 3.8 (mean 2.2) years previously. The majority exhibited growth failure, of multiple aetiology. Ten patients, of whom eight had had previous prophylactic cranial irradiation, had evidence of growth hormone deficiency based on reduced growth hormone reponse to insulin induced hypoglycaemia. Three had evidence of hypothalamic damage. Gonadal failure was common. All four girls of adolescent age (10.6-14.1 years) had ovarian failure requiring sex steroid replacement. Of eight boys of adolescent age (12.3-18.3 years), two had testicular failure requiring sex steroid supplements. Both had had previous testicular irradiation. Five others had compensated gonadal failure; one had normal Leydig cell function. Abnormalities of the TSH response to TRH occurred in 10 patients but only three had overt hypothyroidism. Unlike growth hormone deficiency, gonadal and thyroid dysfunction showed no correlation with previous cranial radiotherapy. (author)
Fang, Yi-Qing; Lu, Ying; Wang, Yong-Jun
2012-03-01
To observe the clinical efficiency and safety of Benazepril and wind dispelling and dampness removing Chinese herbs were singly or combined used in patients with stage 3 chronic kidney disease (CKD 3), and to provide effective integrative medicine methods for treatment of CKD 3. The CKD 3 was allocated to qi and yin deficiency syndrome, inner disturbance of wind and damp syndrome, stasis in Shen meridian syndrome, and inner accumulation of damp and heat syndrome. Recruited were patients of inner disturbance of wind and damp syndrome accompanied or unaccompanied with the other 3 syndrome types. In the prospective, randomized, double blind controlled study, 60 patients confirmed as primary chronic glomerulonephritis (CGN) were randomly assigned to 3 groups with a total course of treatment for 24 weeks. Patients in the Western medicine group (WM, 23 cases) took Benazepril (10 mg/d). Those in the Chinese medicine group (CM, 20 cases) received treatment by syndrome typing. Those in the combination group (17 cases) used the two methods. The therapeutic efficacy and the occurrence of adverse reactions were observed in the 3 groups. The inner disturbance of wind and damp syndrome accompanied qi and yin deficiency syndrome and stasis in Shen meridian syndrome was most often seen in these patients. It accounted for 75.0% in the CM group, 60.9% in the WM group, and 82.4% in the combination group. Totally 54 patients completed this trial. Of them, there were 19 in the CM group, 19 in the WM group, and 16 in the combination group. There was no significant difference in the total effective rate of Chinese medicine syndrome among the 3 groups (84.2%, 78.9%, and 87.5%, respectively) (P>0.05). As for the total effective rate of WM, it was obviously higher in the combination group than in the WM group and the CM group (100.0%, 94.7%, and 94.7%, respectively) (PBenazepril combined with wind dispelling and dampness removing Chinese herbs showed favorable renal protective effects. It
Dissipative quantum trajectories in complex space: Damped harmonic oscillator
International Nuclear Information System (INIS)
Chou, Chia-Chun
2016-01-01
Dissipative quantum trajectories in complex space are investigated in the framework of the logarithmic nonlinear Schrödinger equation. The logarithmic nonlinear Schrödinger equation provides a phenomenological description for dissipative quantum systems. Substituting the wave function expressed in terms of the complex action into the complex-extended logarithmic nonlinear Schrödinger equation, we derive the complex quantum Hamilton–Jacobi equation including the dissipative potential. It is shown that dissipative quantum trajectories satisfy a quantum Newtonian equation of motion in complex space with a friction force. Exact dissipative complex quantum trajectories are analyzed for the wave and solitonlike solutions to the logarithmic nonlinear Schrödinger equation for the damped harmonic oscillator. These trajectories converge to the equilibrium position as time evolves. It is indicated that dissipative complex quantum trajectories for the wave and solitonlike solutions are identical to dissipative complex classical trajectories for the damped harmonic oscillator. This study develops a theoretical framework for dissipative quantum trajectories in complex space.
Dissipative quantum trajectories in complex space: Damped harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Chou, Chia-Chun, E-mail: ccchou@mx.nthu.edu.tw
2016-10-15
Dissipative quantum trajectories in complex space are investigated in the framework of the logarithmic nonlinear Schrödinger equation. The logarithmic nonlinear Schrödinger equation provides a phenomenological description for dissipative quantum systems. Substituting the wave function expressed in terms of the complex action into the complex-extended logarithmic nonlinear Schrödinger equation, we derive the complex quantum Hamilton–Jacobi equation including the dissipative potential. It is shown that dissipative quantum trajectories satisfy a quantum Newtonian equation of motion in complex space with a friction force. Exact dissipative complex quantum trajectories are analyzed for the wave and solitonlike solutions to the logarithmic nonlinear Schrödinger equation for the damped harmonic oscillator. These trajectories converge to the equilibrium position as time evolves. It is indicated that dissipative complex quantum trajectories for the wave and solitonlike solutions are identical to dissipative complex classical trajectories for the damped harmonic oscillator. This study develops a theoretical framework for dissipative quantum trajectories in complex space.
Damped oscillatory integrals and boundedness problem for maximal operators
International Nuclear Information System (INIS)
Ikromov, Isroil A.
2003-06-01
We consider a real-analytic hypersurface S in IR n+1 with surface measure dσ, ψ is a compactly supported non-negative smooth cut-off function, and we let dμ q be the surface measure with dμ q ψvertical barΛ(X)vertical bar q dσ, where Λ(X) is a damping factor defined by the matrix of a second fundamental form of the surface. We show that if S is a real analytic hypersurface, then μ-circumflex q (ξ) decays as O(vertical barξvertical bar -(1/2+ε) ), where ε > 0, provided q > 3/2. We also consider applications involving maximal operators associated to averages of functions over hypersurfaces. (author)
Advanced damped detuned structure (DDS) development at SLAC
International Nuclear Information System (INIS)
Jones, R.M.; Kroll, N.M.; Miller, R.H.; Ruth, R.D.; Wang, J.W.
1997-05-01
The first damped detuned accelerator structure, DDS 1, has been built, tested in the ASSET experiment, and installed in the NLCTA. The planning and construction of a series of further structures, incorporating some modifications, is under way. DDS 2, 3, and 4 all incorporate the same basic design as DDS 1. The manifold design for the last 5 % of the downstream end of the structure has been modified to accommodate improvements in the manifold loads. Calculations based on the spectral function method indicate, on average, a factor two or better reduction in the long range wake. Modest modifications in the distribution of geometrical detuning parameters along the structure which, according to calculations based on spectral function theory, significantly improve the short range wake will be incorporated in DDS 3 and 4. The basic cell configuration will be redesigned in DDS 5 with the intention of improving shunt impedance as well as incorporating further improvements in the wake
Electric Generator in the System for Damping Oscillations of Vehicles
Directory of Open Access Journals (Sweden)
Serebryakov A.
2017-04-01
Full Text Available The control systems for the objects of industry, power generation, transport, etc. are extremely complicated; functional efficiency of these systems determines to a great extent the safe and non-polluting operation as well as convenience of service and repair of such objects. The authors consider the possibility to improve the efficiency of systems for damping oscillations in transport using a combination of electrical (generators of rotational and linear types and hydraulic means. Better efficiency of functioning is achieved through automatic control over the operational conditions of such a system in order to make it adaptive to variations in the road profile and ambient temperature; besides, it is possible to produce additional electric energy.
Electric Generator in the System for Damping Oscillations of Vehicles
Serebryakov, A.; Kamolins, E.; Levin, N.
2017-04-01
The control systems for the objects of industry, power generation, transport, etc. are extremely complicated; functional efficiency of these systems determines to a great extent the safe and non-polluting operation as well as convenience of service and repair of such objects. The authors consider the possibility to improve the efficiency of systems for damping oscillations in transport using a combination of electrical (generators of rotational and linear types) and hydraulic means. Better efficiency of functioning is achieved through automatic control over the operational conditions of such a system in order to make it adaptive to variations in the road profile and ambient temperature; besides, it is possible to produce additional electric energy.
International Nuclear Information System (INIS)
Pradeep, R. Gladwin; Chandrasekar, V. K.; Senthilvelan, M.; Lakshmanan, M.
2009-01-01
In this paper we point out the existence of a remarkable nonlocal transformation between the damped harmonic oscillator and a modified Emden-type nonlinear oscillator equation with linear forcing, xe+αxx+βx 3 +γx=0, which preserves the form of the time independent integral, conservative Hamiltonian, and the equation of motion. Generalizing this transformation we prove the existence of nonstandard conservative Hamiltonian structure for a general class of damped nonlinear oscillators including Lienard-type systems. Further, using the above Hamiltonian structure for a specific example, namely, the generalized modified Emden equation xe+αx q x+βx 2q+1 =0, where α, β, and q are arbitrary parameters, the general solution is obtained through appropriate canonical transformations. We also present the conservative Hamiltonian structure of the damped Mathews-Lakshmanan oscillator equation. The associated Lagrangian description for all the above systems is also briefly discussed.
Ottander, John A.; Hall, Robert A.; Powers, J. F.
2018-01-01
A method is presented that allows for the prediction of the magnitude of limit cycles due to adverse control-slosh interaction in liquid propelled space vehicles using non-linear slosh damping. Such a method is an alternative to the industry practice of assuming linear damping and relying on: mechanical slosh baffles to achieve desired stability margins; accepting minimal slosh stability margins; or time domain non-linear analysis to accept time periods of poor stability. Sinusoidal input describing functional analysis is used to develop a relationship between the non-linear slosh damping and an equivalent linear damping at a given slosh amplitude. In addition, a more accurate analytical prediction of the danger zone for slosh mass locations in a vehicle under proportional and derivative attitude control is presented. This method is used in the control-slosh stability analysis of the NASA Space Launch System.
DEFF Research Database (Denmark)
Holm, Bente; Thorborg, Kristian; Husted, Henrik
2013-01-01
By measuring very early changes in muscle strength and functional performance after fast-track total hip arthroplasty (THA), post-operative rehabilitation, introduced soon after surgery, can be designed to specifically target identified deficits.......By measuring very early changes in muscle strength and functional performance after fast-track total hip arthroplasty (THA), post-operative rehabilitation, introduced soon after surgery, can be designed to specifically target identified deficits....
Damping Analysis of Cylindrical Composite Structures with Enhanced Viscoelastic Properties
Kliem, Mathias; Høgsberg, Jan; Vanwalleghem, Joachim; Filippatos, Angelos; Hoschützky, Stefan; Fotsing, Edith-Roland; Berggreen, Christian
2018-04-01
Constrained layer damping treatments are widely used in mechanical structures to damp acoustic noise and mechanical vibrations. A viscoelastic layer is thereby applied to a structure and covered by a stiff constraining layer. When the structure vibrates in a bending mode, the viscoelastic layer is forced to deform in shear mode. Thus, the vibration energy is dissipated as low grade frictional heat. This paper documents the efficiency of passive constrained layer damping treatments for low frequency vibrations of cylindrical composite specimens made of glass fibre-reinforced plastics. Different cross section geometries with shear webs have been investigated in order to study a beneficial effect on the damping characteristics of the cylinder. The viscoelastic damping layers are placed at different locations within the composite cylinder e.g. circumferential and along the neutral plane to evaluate the location-dependent efficiency of constrained layer damping treatments. The results of the study provide a thorough understanding of constrained layer damping treatments and an improved damping design of the cylindrical composite structure. The highest damping is achieved when placing the damping layer in the neutral plane perpendicular to the bending load. The results are based on free decay tests of the composite structure.
Gauthier-Kwan, Olivier Y; Dobransky, Johanna S; Dervin, Geoffrey F
2018-02-05
Outpatient total knee arthroplasty (TKA) has been made possible with advances in perioperative care and standardized clinical inpatient pathways. While many studies report on benefits of outpatient programs, none explore patient-reported outcome measures. As such, our goals were to compare the short-term quality of recovery; highlight postdischarge hospital resources utilization; and report on 2-year functional outcomes scores. This was a prospective comparative cohort study of 43 inpatients (43 TKAs) and 43 outpatients (43 TKAs) operated on by a single surgeon between September 28, 2010 and May 5, 2015. All patients were given a diary to complete at 1, 3, 7, 14, and 28 days postoperatively; we collected 90-day complications, readmissions, and emergency department visits; Knee Injury and Osteoarthritis Outcome Score and Western Ontario and McMaster Universities Osteoarthritis Index scores were completed preoperatively and 2 years postoperatively. SPSS (IBM, version 22.0) was used for all statistical analyses. Quality of recovery (QoR-9) was similar in the outpatient TKA group compared with the inpatient group. No statistically significant differences were observed for Knee Injury and Osteoarthritis Outcome Score and Western Ontario and McMaster Universities Osteoarthritis Index subscores (P > .05). There was 1 readmission in both outpatient and inpatient groups. Six inpatients and 8 outpatients returned to the emergency department for any reason within 90 days, with no statistical significance observed between the 2 groups (P = .771). Outpatient TKA in selected patients produced similar short-term and 2-year patient-reported outcome measures and a comparable 90-day postdischarge hospital resource utilization when compared to an inpatient cohort, supporting further investigation into outpatient TKA. Copyright © 2018 Elsevier Inc. All rights reserved.
Medina-Mirapeix, Francesc; Vivo-Fernández, Iván; López-Cañizares, Juan; García-Vidal, José A; Benítez-Martínez, Josep Carles; Del Baño-Aledo, María Elena
2018-01-01
The objective was to determine the inter-observer and test/retest reliability of the "Five-repetition sit-to-stand" (5STS) test in patients with total knee replacement (TKR). To explore correlation between 5STS and two mobility tests. A reliability study was conducted among 24 (mean age 72.13, S.D. 10.67; 50% were women) outpatients with TKR. They were recruited from a traumatology unit of a public hospital via convenience sampling. A physiotherapist and trauma physician assessed each patient at the same time. The same physiotherapist realized a 5STS second measurement 45-60min after the first one. Reliability was assessed with intraclass correlation coefficients (ICCs) and Bland-Altman plots. Pearson coefficient was calculated to assess the correlation between 5STS, time up to go test (TUG) and four meters gait speed (4MGS). ICC for inter-observer and test-retest reliability of the 5STS were 0.998 (95% confidence interval [CI], 0.995-0.999) and 0.982 (95% CI, 0.959-0.992). Bland-Altman plot inter-observer showed limits between -0.82 and 1.06 with a mean of 0.11 and no heteroscedasticity within the data. Bland-Altman plot for test-retest showed the limits between 1.76 and 4.16, a mean of 1.20 and heteroscedasticity within the data. Pearson correlation coefficient revealed significant correlation between 5STS and TUG (r=0.7, ptest-retest reliability when it is used in people with TKR, and also significant correlation with other functional mobility tests. These findings support the use of 5STS as outcome measure in TKR population. Copyright © 2017 Elsevier B.V. All rights reserved.
Manjunatha, Revanasiddappa; Shivappa Suresh, Gurukar; Melo, Jose Savio; D'Souza, Stanislaus F; Venkatesha, Thimmappa Venkatarangaiah
2012-09-15
Cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) have been covalently immobilized onto functionalized graphene (FG) modified graphite electrode. Enzymes modified electrodes were characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). FG accelerates the electron transfer from electrode surface to the immobilized ChOx, achieving the direct electrochemistry of ChOx. A well defined redox peak was observed, corresponding to the direct electron transfer of the FAD/FADH(2) of ChOx. The electron transfer coefficient (α) and electron transfer rate constant (K(s)) were calculated and their values are found to be 0.31 and 0.78 s(-1), respectively. For the free cholesterol determination, ChOx-FG/Gr electrode exhibits a sensitive response from 50 to 350 μM (R=-0.9972) with a detection limit of 5 μM. For total cholesterol determination, co-immobilization of ChEt and ChOx on modified electrode, i.e. (ChEt/ChOx)-FG/Gr electrode showed linear range from 50 to 300 μM (R=-0.9982) with a detection limit of 15 μM. Some common interferents like glucose, ascorbic acid and uric acid did not cause any interference, due to the use of a low operating potential. The FG/Gr electrode exhibits good electrocatalytic activity towards hydrogen peroxide (H(2)O(2)). A wide linear response to H(2)O(2) ranging from 0.5 to 7 mM (R=-0.9967) with a sensitivity of 443.25 μA mM(-1) cm(-2) has been obtained. Copyright © 2012 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Shayeghi, H., E-mail: hshayeghi@gmail.co [Technical Engineering Department, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Shayanfar, H.A. [Center of Excellence for Power System Automation and Operation, Electrical Engineering Department, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Jalilzadeh, S.; Safari, A. [Technical Engineering Department, Zanjan University, Zanjan (Iran, Islamic Republic of)
2010-10-15
In this paper, a new approach based on the particle swarm optimization (PSO) technique is proposed to tune the parameters of the thyristor controlled series capacitor (TCSC) power oscillation damping controller. The design problem of the damping controller is converted to an optimization problem with the time-domain-based objective function which is solved by a PSO technique which has a strong ability to find the most optimistic results. To ensure the robustness of the proposed stabilizers, the design process takes a wide range of operating conditions into account. The performance of the newly designed controller is evaluated in a four-machine power system subjected to the different types of disturbances in comparison with the genetic algorithm based damping controller. The effectiveness of the proposed controller is demonstrated through the nonlinear time-domain simulation and some performance indices studies. The results analysis reveals that the tuned PSO based TCSC damping controller using the proposed fitness function has an excellent capability in damping power system inter-area oscillations and enhances greatly the dynamic stability of the power systems. Moreover, it is superior to the genetic algorithm based damping controller.
Damping of acoustic flexural phonons in silicene: influence on high-field electronic transport
Rengel, Raúl; Iglesias, José M.; Mokhtar Hamham, El; Martín, María J.
2018-06-01
Silicene is a two-dimensional buckled material with broken horizontal mirror symmetry and Dirac-like dispersion. Under such conditions, flexural acoustic (ZA) phonons play a dominant role. Consequently, it is necessary to consider some suppression mechanism for electron–phonon interactions with long wavelengths in order to reach mobilities useful for electronic applications. In this work, we analyze, by means of an ensemble Monte Carlo simulator, the influence of several possibilities for the description of the effect of ZA phonon damping on electronic transport in silicene. The results show that a hard cutoff situation (total suppression for phonons with a wavelength longer than a critical one), as it has been proposed in the literature, does not yield a realistic picture regarding the electronic distribution function, and it artificially induces a negative differential resistance at moderate and high fields. Sub-parabolic dispersions, on the other hand, may provide a more realistic description in terms of the behavior of the electron distribution in the momentum space, but need extremely short cutoff wavelengths to reach functional mobility and drift velocity values.
Digital notch filter based active damping for LCL filters
DEFF Research Database (Denmark)
Yao, Wenli; Yang, Yongheng; Zhang, Xiaobin
2015-01-01
. In contrast, the active damping does not require any dissipation elements, and thus has become of increasing interest. As a result, a vast of active damping solutions have been reported, among which multi-loop control systems and additional sensors are necessary, leading to increased cost and complexity....... In this paper, a notch filter based active damping without the requirement of additional sensors is proposed, where the inverter current is employed as the feedback variable. Firstly, a design method of the notch filter for active damping is presented. The entire system stability has then been investigated...... in the z-domain. Simulations and experiments are carried out to verify the proposed active damping method. Both results have confirmed that the notch filter based active damping can ensure the entire system stability in the case of resonances with a good system performance....
Controlled damping of a physical pendulum: experiments near critical conditions
International Nuclear Information System (INIS)
Gonzalez, Manuel I; Bol, Alfredo
2006-01-01
This paper presents an experimental device for the study of damped oscillatory motion along with three associated experiments. Special emphasis is given on both didactic aspects and the interactivity of the experimental set-up, in order to assist students in understanding fundamental aspects of damped oscillatory motion and allow them to directly compare their experimental results with the well-known theory they can find in textbooks. With this in mind, a physical pendulum was selected with an eddy-current damping system that allows the damping conditions to be controlled with great precision. The three experiments examine accurate control of damping, frequency shift near critical damping and the transition from underdamped to overdamped conditions
Special class of nonlinear damping models in flexible space structures
Hu, Anren; Singh, Ramendra P.; Taylor, Lawrence W.
1991-01-01
A special class of nonlinear damping models is investigated in which the damping force is proportional to the product of positive integer or the fractional power of the absolute values of displacement and velocity. For a one-degree-of-freedom system, the classical Krylov-Bogoliubov 'averaging' method is used, whereas for a distributed system, both an ad hoc perturbation technique and the finite difference method are employed to study the effects of nonlinear damping. The results are compared with linear viscous damping models. The amplitude decrement of free vibration for a single mode system with nonlinear models depends not only on the damping ratio but also on the initial amplitude, the time to measure the response, the frequency of the system, and the powers of displacement and velocity. For the distributed system, the action of nonlinear damping is found to reduce the energy of the system and to pass energy to lower modes.
An experimental study on damping characteristics of thermal insulation
International Nuclear Information System (INIS)
Chiba, Toshio; Kobayashi, Hiroe; Aida, Shigekazu; Wada, Hidetoshi
1984-01-01
The damping ratio is one of the most important parameters in seismic analysis of piping systems in a nuclear power plant. Thermal insulation is considered contributing to the damping characteristics of piping systems. At the 6th SMiRT and 1983 ASME PVP conferences, the damping effect and damping estimating formula were presented as a result of regression analysis using the component test data for 2,4 and 8B diameter piping and the proof model test for 1,2 and 4B piping system. In this study, in order to clarify the damping characteristics of a larger diameter piping than 8B,the component test of 12 and 20B diameter piping with insulation was performed. From the results of these tests and the data survey of the previous papers, it was found that the damping ratio of anactual piping system with thermal insulation is at minimum 1% for all size diameter piping. (author)
An experimental study on damping characteristics of thermal insulation
International Nuclear Information System (INIS)
Chiba, T.; Kobayashi, H.
1985-01-01
The damping ratio is one of the most important parameters in seismic analysis of nuclear power plant piping systems. Thermal Insulation is considered to contribute to the damping characteristics of piping systems. In the 6th SMiRT conference and 1983 ASME PVP, the damping effect and damping estimating formula was presented as a result of regression analysis from the component tests of 2'' , 4'', and 8'' diameter piping and the proof model test of 1'', 2'' and 4'' piping. In this study, in order to clarify the damping characteristics of larger diameter piping than 8'', the component test of 12'' and 20'' diameter piping with insulation was performed. From the results of these tests and the data survey of the previous papers it was found that the damping ratio of actual piping system with thermal insulation is at least 1% for all size diameter piping
Oscillation damping of chiral string loops
International Nuclear Information System (INIS)
Babichev, Eugeny; Dokuchaev, Vyacheslav
2002-01-01
Chiral cosmic string loops tend to the stationary (vorton) configuration due to energy loss into gravitational and electromagnetic radiation. We describe the asymptotic behavior of near stationary chiral loops and their fading to vortons. General limits on the gravitational and electromagnetic energy losses by near stationary chiral loops are found. For these loops we estimate the oscillation damping time. We present solvable examples of gravitational radiation energy loss by some chiral loop configurations. The analytical dependence of string energy with time is found in the case of the chiral ring with small amplitude radial oscillations
Power Oscillations Damping in DC Microgrids
Hamzeh, Mohsen; Ghafouri, Mohsen; Karimi, Houshang; Sheshyekani, Keyhan; Guerrero, Josep M.
2016-01-01
This paper proposes a new control strategy for damping of power oscillations in a multi-source dc microgrid. A parallel combination of a fuel cell (FC), a photovoltaic (PV) system and a supercapacitor (SC) are used as a hybrid power conversion system (HPCS). The SC compensates for the slow transient response of the FC stack. The HPCS controller comprises a multi-loop voltage controller and a virtual impedance loop for power management. The virtual impedance loop uses a dynamic droop gain to a...
Hyperchaotic circuit with damped harmonic oscillators
DEFF Research Database (Denmark)
Lindberg, Erik; Murali, K.; Tamasevicius, A.
2001-01-01
A simple fourth-order hyperchaotic circuit with damped harmonic oscillators is described. ANP3 and PSpice simulations including an eigenvalue study of the linearized Jacobian are presented together with a hardware implementation. The circuit contains two inductors with series resistance, two ideal...... capacitors and one nonlinear active conductor. The Lyapunov exponents are presented to confirm the hyperchaotic nature of the oscillations of the circuit. The nonlinear conductor is realized with a diode. A negative impedance converter and a linear resistor. The performance of the circuit is investigated...... by means of numerical integration of the appropriate differential equations....
System for damping vibrations in a turbine
Roberts, III, Herbert Chidsey; Johnson, Curtis Alan; Taxacher, Glenn Curtis
2015-11-24
A system for damping vibrations in a turbine includes a first rotating blade having a first ceramic airfoil, a first ceramic platform connected to the first ceramic airfoil, and a first root connected to the first ceramic platform. A second rotating blade adjacent to the first rotating blade includes a second ceramic airfoil, a second ceramic platform connected to the second ceramic airfoil, and a second root connected to the second ceramic platform. A non-metallic platform damper has a first position in simultaneous contact with the first and second ceramic platforms.
Status of the SLC damping rings
International Nuclear Information System (INIS)
Hutton, A.M.; Davies-White, W.A.; Delahaye, J.P.
1985-06-01
Electron beams of full design energy 1.21 GeV and nearly full design intensity 4 x 10 10 particles/pulse (design 5 x 10 10 ) have been extracted from the Stanford Linac and successfully stored in the electron damping ring. Beams of less intensity have been extracted from the ring and reinjected into the Linac. The present intensity limits are not thought to be fundamental. The operating experience with the electron ring and the status of the construction of the positron ring will be discussed. 11 refs., 1 fig., 2 tabs
Coherent Synchrotron Radiation effect in damping rings
International Nuclear Information System (INIS)
Raubenheimer, T
2004-01-01
Coherent Synchrotron Radiation (CSR) can play an important role by not only increasing the energy spread and emittance of a beam, but also leading to a potential instability. Previous studies of the CSR induced longitudinal instability were carried out for the CSR impedance due to dipole magnets. In this paper, the instability due to the CSR impedance from a wiggler is studied assuming a large wiggler parameter K. The primary consideration is a low frequency microwave-like instability in the damping rings of several linear collider projects. The threshold is determined by the instability with the longest possible wavelength
Transport description of damped nuclear reactions
International Nuclear Information System (INIS)
Randrup, J.
1983-04-01
Part I is an elementary introduction to the general transport theory of nuclear dynamics. It can be read without any special knowledge of the field, although basic quantum mechanics is required for the formal derivation of the general expression for the transport coefficients. The results can also be used in a wider context than the present one. Part II gives the student an up-to-date orientation about recent progress in the understanding of the angular-momentum variables in damped reactions. The emphasis is here on the qualitative understanding of the physics rather than the, at times somewhat tedious, formal derivations
Thermal equilibrium in strongly damped collisions
International Nuclear Information System (INIS)
Samaddar, S.K.; De, J.N.; Krishan, K.
1985-01-01
Energy division between colliding nuclei in damped collisions is studied in the statistical nucleon exchange model. The reactions 56 Fe+ 165 Ho and 56 Fe+ 238 U at incident energy of 465 MeV are considered for this purpose. It is found that the excitation energy is approximately equally shared between the nuclei for the peripheral collisions and the systems slowly approach equilibrium for more central collisions. This is in conformity with the recent experimental observations. The calculated variances of the charge distributions are found to depend appreciably on the temperature and are in very good agreement with the experimental data
Study on Radiation Condition in DAMPE Orbit by Analyzing the Engineering Data of BGO Calorimeter
Feng, Changqing; Liu, Shubin; Zhang, Yunlong; Ma, Siyuan
2016-07-01
The DAMPE (DArk Matter Particle Explorer) is a scientific satellite which was successfully launched into a 500 Km sun-synchronous orbit, on December 17th, 2015, from the Jiuquan Satellite Launch Center of China. The major scientific objectives of the DAMPE mission are primary cosmic ray, gamma ray astronomy and dark matter particles, by observing high energy primary cosmic rays, especially positrons/electrons and gamma rays with an energy range from 5 GeV to 10 TeV. The BGO calorimeter is a critical sub-detector of DAMPE payload, for measuring the energy of cosmic particles, distinguishing positrons/electrons and gamma rays from hadron background, and providing trigger information. It utilizes 308 BGO (Bismuth Germanate Oxide) crystal logs with the size of 2.5cm*2.5cm*60cm for each log, to form a total absorption electromagnetic calorimeter. All the BGO logs are stacked in 14 layers, with each layer consisting of 22 BGO crystal logs and each log is viewed by two Hamamatsu R5610A PMTs (photomultiplier tubes), from both sides respectively. In order to achieve a large dynamic range, each PMT base incorporates a three dynode (2, 5, 8) pick off, which results in 616 PMTs and 1848 signal channels. The readout electronics system, which consists of 16 FEE (Front End Electronics) modules, was developed. Its main functions are based on the Flash-based FPGA (Field Programmable Gate Array) chip and low power, 32-channel VA160 and VATA160 ASICs (Application Specific Integrated Circuits) for precisely measuring the charge of PMT signals and providing "hit" signals as well. The hit signals are sent to the trigger module of PDPU (Payload Data Process Unit) and the hit rates of each layer is real-timely recorded by counters and packed into the engineering data, which directly reflect the flux of particles which fly into or pass through the detectors. In order to mitigate the SEU (Single Event Upset) effect in radioactive space environment, certain protecting methods, such as TMR
Rising damp in building walls: the wall base ventilation system
Energy Technology Data Exchange (ETDEWEB)
Guimaraes, A.S.; Delgado, J.M.P.Q.; Freitas, V.P. de [Faculdade de Engenharia da Universidade do Porto, Laboratorio de Fisica das Construcoes (LFC), Departamento de Engenharia Civil, Porto (Portugal)
2012-12-15
This work intends to validate a new system for treating rising damp in historic buildings walls. The results of laboratory experiments show that an efficient way of treating rising damp is by ventilating the wall base, using the HUMIVENT technique. The analytical model presented describes very well the observed features of rising damp in walls, verified by laboratory tests, who contributed for a simple sizing of the wall base ventilation system that will be implemented in historic buildings. (orig.)
Complex modes and frequencies in damped structural vibrations
DEFF Research Database (Denmark)
Krenk, Steen
2004-01-01
It is demonstrated that the state space formulation of the equation of motion of damped structural elements like cables and beams leads to a symmetric eigenvalue problem if the stiffness and damping operators are self-adjoint, and that this is typically the case in the absence of gyroscopic forces....... The corresponding theory of complex modal analysis of continuous systems is developed and illustrated in relation to optimal damping and impulse response of cables and beams with discrete dampers....
On the origin of nonlocal damping in plasmonic monomers and dimers
Tserkezis, Christos; Yan, Wei; Hsieh, Wenting; Sun, Greg; Khurgin, Jacob B.; Wubs, Martijn; Mortensen, N. Asger
2017-09-01
The origin and importance of nonlocal damping is discussed through simulations with the generalized nonlocal optical response (GNOR) theory, in conjunction with time-dependent density functional theory (TDDFT) calculations and equivalent circuit modeling, for some of the most typical plasmonic architectures: metal-dielectric interfaces, metal-dielectric-metal gaps, spherical nanoparticles and nanoparticle dimers. It is shown that diffusive damping, as introduced by the convective-diffusive GNOR theory, describes well the enhanced losses and plasmon broadening predicted by ab initio calculations in few-nm particles or few-to-sub-nm gaps. Through the evaluation of a local effective dielectric function, it is shown that absorptive losses appear dominantly close to the metal surface, in agreement with TDDFT and the mechanism of Landau damping due to generation of electron-hole pairs near the interface. Diffusive nonlocal theories provide therefore an efficient means to tackle plasmon damping when electron tunneling can be safely disregarded, without the need to resort to more accurate, but time-consuming fully quantum-mechanical studies.
PSS and TCSC damping controller coordinated design using PSO in multi-machine power system
Energy Technology Data Exchange (ETDEWEB)
Shayeghi, H., E-mail: hshayeghi@gmail.co [Technical Engineering Department, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Safari, A.; Shayanfar, H.A. [Center of Excellence for Power System Automation and Operation, Electrical Engineering Department, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)
2010-12-15
The paper develops a new design procedure for simultaneous coordinated designing of the thyristor controlled series capacitor (TCSC) damping controller and power system stabilizer (PSS) in multi-machine power system. The coordinated design problem of PSS and TCSC damping controllers over a wide range of loading conditions is converted to an optimization problem with the time domain-based objective function that is solved by a particle swarm optimization (PSO) technique which has a strong ability to find the most optimistic results. By minimizing the proposed fitness function in which oscillatory characteristics between areas are included and thus the interactions among the TCSC controller and PSS under transient conditions in the multi-machine power system are improved. To ensure the robustness of the proposed stabilizers, the design process takes a wide range of operating conditions into account. The effectiveness of the proposed controller is demonstrated through the nonlinear time-domain simulation and some performance indices studies. The results of these studies show that the proposed coordinated controllers have an excellent capability in damping power system inter-area oscillations and enhance greatly the dynamic stability of the power system. Moreover, it is superior to both the uncoordinated designed stabilizers of the PSS and the TCSC damping controller.
Damped driven coupled oscillators: entanglement, decoherence and the classical limit
Energy Technology Data Exchange (ETDEWEB)
Mancilla, R D Guerrero; Rey-Gonzalez, R R; Fonseca-Romero, K M [Grupo de Optica e Informacion Cuantica, Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia)], E-mail: rdguerrerom@unal.edu.co, E-mail: rrreyg@unal.edu.co, E-mail: kmfonsecar@unal.edu.co
2009-03-13
We investigate the quantum-classical border, the entanglement and decoherence of an analytically solvable model, comprising a first subsystem (a harmonic oscillator) coupled to a driven and damped second subsystem (another harmonic oscillator). We choose initial states whose dynamics is confined to a couple of two-level systems, and show that the maximum value of entanglement between the two subsystems, as measured by concurrence, depends on the dissipation rate to the coupling-constant ratio and the initial state. While in a related model the entropy of the first subsystem (a two-level system) never grows appreciably (for large dissipation rates), in our model it reaches a maximum before decreasing. Although both models predict small values of entanglement and dissipation, for fixed times of the order of the inverse of the coupling constant and large dissipation rates, these quantities decrease faster, as a function of the ratio of the dissipation rate to the coupling constant, in our model.
Damped driven coupled oscillators: entanglement, decoherence and the classical limit
International Nuclear Information System (INIS)
Mancilla, R D Guerrero; Rey-Gonzalez, R R; Fonseca-Romero, K M
2009-01-01
We investigate the quantum-classical border, the entanglement and decoherence of an analytically solvable model, comprising a first subsystem (a harmonic oscillator) coupled to a driven and damped second subsystem (another harmonic oscillator). We choose initial states whose dynamics is confined to a couple of two-level systems, and show that the maximum value of entanglement between the two subsystems, as measured by concurrence, depends on the dissipation rate to the coupling-constant ratio and the initial state. While in a related model the entropy of the first subsystem (a two-level system) never grows appreciably (for large dissipation rates), in our model it reaches a maximum before decreasing. Although both models predict small values of entanglement and dissipation, for fixed times of the order of the inverse of the coupling constant and large dissipation rates, these quantities decrease faster, as a function of the ratio of the dissipation rate to the coupling constant, in our model
Response of resonant gravitational wave detectors to damped sinusoid signals
International Nuclear Information System (INIS)
Pai, A; Celsi, C; Pallottino, G V; D'Antonio, S; Astone, P
2007-01-01
Till date, the search for burst signals with resonant gravitational wave (GW) detectors has been done using the δ-function approximation for the signal, which was reasonable due to the very small bandwidth of these detectors. However, now with increased bandwidth (of the order of 10 or more Hz) and with the possibility of comparing results with interferometric GW detectors (broad-band), it is very important to exploit the resonant detectors' capability to detect also signals with specific wave shapes. As a first step, we present a study of the response of resonant GW detectors to damped sinusoids with given frequency and decay time and report on the development of a filter matched to these signals. This study is a preliminary step towards the comprehension of the detector response and of the filtering for signals such as the excitation of stellar quasi-normal modes
Nucleon exchange and heat partition in damped collisions
International Nuclear Information System (INIS)
Planeta, R.; Kwiatkowski, K.; Zhou, S.H.; Viola, V.E.; Breuer, H.; McMahan, M.A.; Randrup, J.; Mignerey, A.C.
1989-01-01
Mass and charge distributions have been measured for damped projectile-like fragments in the reaction /sup 74/Ge+/sup 165/Ho at 8.5 MeV per nucleon bombarding energy. Coincidences were measured between angle-correlated reaction partners in order to derive the primary mass distribution and the excitation energy distribution for projectile-like fragments. The evolution of the primary N and Z distributions as a function of energy loss is found to deviate significantly from predictions of the nucleon exchange transport model. The fraction of excitation energy residing in the projectile-like fragment is shown to depend both upon energy loss and the direction of the nucleon flow
An identification method for damping ratio in rotor systems
Wang, Weimin; Li, Qihang; Gao, Jinji; Yao, Jianfei; Allaire, Paul
2016-02-01
Centrifugal compressor testing with magnetic bearing excitations is the last step to assure the compressor rotordynamic stability in the designed operating conditions. To meet the challenges of stability evaluation, a new method combining the rational polynomials method (RPM) with the weighted instrumental variables (WIV) estimator to fit the directional frequency response function (dFRF) is presented. Numerical simulation results show that the method suggested in this paper can identify the damping ratio of the first forward and backward modes with high accuracy, even in a severe noise environment. Experimental tests were conducted to study the effect of different bearing configurations on the stability of rotor. Furthermore, two example centrifugal compressors (a nine-stage straight-through and a six-stage back-to-back) were employed to verify the feasibility of identification method in industrial configurations as well.
Structural dynamic analysis with generalized damping models analysis
Adhikari , Sondipon
2013-01-01
Since Lord Rayleigh introduced the idea of viscous damping in his classic work ""The Theory of Sound"" in 1877, it has become standard practice to use this approach in dynamics, covering a wide range of applications from aerospace to civil engineering. However, in the majority of practical cases this approach is adopted more for mathematical convenience than for modeling the physics of vibration damping. Over the past decade, extensive research has been undertaken on more general ""non-viscous"" damping models and vibration of non-viscously damped systems. This book, along with a related book
Dynamic apeerture in damping rings with realistic wigglers
Energy Technology Data Exchange (ETDEWEB)
Cai, Yunhai; /SLAC
2005-05-04
The International Linear Collider based on superconducting RF cavities requires the damping rings to have extremely small equilibrium emittance, huge circumference, fast damping time, and large acceptance. To achieve all of these requirements is a very challenging task. In this paper, we will present a systematic approach to designing the damping rings using simple cells and non-interlaced sextupoles. The designs of the damping rings with various circumferences and shapes, including dogbone, are presented. To model realistic wigglers, we have developed a new hybrid symplectic integrator for faster and accurate evaluation of dynamic aperture of the lattices.
Enhancing the Damping Properties of Viscoelastic Composites by Topology Optimization
DEFF Research Database (Denmark)
Andreasen, Casper Schousboe; Andreassen, Erik; Sigmund, Ole
Vibrations, if undamped, might be annoying or even dangerous. Most often some kind of damping mechanism is applied in order to limit the vibration level. Vibration insulators, for instance of rubber material, have favorable damping characteristics but lack the structural stiffness often needed...... in engineering structures. Thus, materials or composites with high stiffness and high damping are of great interest to the industry. The inherent compromise between high stiffness and high damping in viscoelastic materials has been treated theoretically [2, 3] and experimentally [1]. It has been shown that high...
Amplitude dependent damping in single crystalline high purity molybdenum
International Nuclear Information System (INIS)
Zelada-Lambri, G.I; Lambri, O.A; Garcia, J.A; Lomer, J.N
2004-01-01
Amplitude dependent damping measurements were performed on high purity single crystalline molybdenum at several different constant temperatures between room temperature and 1273K. The employed samples were single crystals with the orientation, having a residual resistivity ratio of about 8000. Previously to the amplitude dependent damping tests, the samples were subjected to different thermomechanical histories. Amplitude dependent damping effects appear only during the first heating run in temperature where the samples have the thermomechanical state of the deformation process at room temperature. In the subsequent run-ups in temperature, i.e, after subsequent annealings, amplitude dependent damping effects were not detected (au)
Damping element for reducing the vibration of an airfoil
Campbell, Christian X; Marra, John J
2013-11-12
An airfoil (10) is provided with a tip (12) having an opening (14) to a center channel (24). A damping element (16) is inserted within the opening of the center channel, to reduce an induced vibration of the airfoil. The mass of the damping element, a spring constant of the damping element within the center channel, and/or a mounting location (58) of the damping element within the center channel may be adjustably varied, to shift a resonance frequency of the airfoil outside a natural operating frequency of the airfoil.
Small horizontal emittance in the TESLA damping ring
International Nuclear Information System (INIS)
Decking, W.
2001-01-01
The present TESLA damping ring is designed for a normalized horizontal emittance of 8x10 -6 m. γ-γ collisions at the TESLA linear collider will benefit from a further decrease of the horizontal emittance. This paper reviews the processes which limit the horizontal emittance in the damping ring. Preliminary estimates on the smallest horizontal emittance for the present TESLA damping ring design as well as an ultimate limit of the emittance reachable with the TESLA damping ring concept will be given
Damping of coherent oscillations in intense ion beams
International Nuclear Information System (INIS)
Karpov, Ivan
2017-01-01
Transverse decoherence of a displaced ion bunch is an important phenomenon in synchrotrons and storage rings. An offset can be caused by an injection error after the bunch-to-bucket transfer between synchrotrons or by an externally generated kick. Decoherence results in a transverse emittance blowup, which can cause particle losses and a beam quality degradation. To prevent the beam blowup, a transverse feedback system (TFS) can be used. The damping time should be shorter than the characteristic decoherence time, which can be strongly affected by the interplay of different intensity effects (e.g., space charge and impedances). This thesis describes the development of the analytical models that explain decoherence and emittance growth with chromaticity, space charge, and image charges within the first synchrotron period. The pulsed response function including intensity effects was derived from the model for beam transfer functions. For a coasting beam, the two- dimensional model shows that space charge slows down and above intensity threshold suppresses decoherence. These predictions were confirmed by particle tracking simulations with self-consistent space charge fields. Additionally, halo buildup and losses during decoherence were observed in simulations. These effects were successfully interpreted using a non self-consistent particle-core model. The two-dimensional model was extended to the bunched beams. The simulation results reproduce the analytical predictions. The intensity threshold of decoherence suppression is higher in comparison to a coasting beam, image charges can restore decoherence. In the present work dedicated experiments were performed in the SIS18 synchrotron at GSI Darmstadt and the results were compared with simulations and analytical predictions. The contribution of nonlinearities and image charges is negligible while chromaticity and space charge dominate decoherence. To study the damping efficiency of TFS, a comprehensive TFS module was
Damping of coherent oscillations in intense ion beams
Energy Technology Data Exchange (ETDEWEB)
Karpov, Ivan
2017-02-06
Transverse decoherence of a displaced ion bunch is an important phenomenon in synchrotrons and storage rings. An offset can be caused by an injection error after the bunch-to-bucket transfer between synchrotrons or by an externally generated kick. Decoherence results in a transverse emittance blowup, which can cause particle losses and a beam quality degradation. To prevent the beam blowup, a transverse feedback system (TFS) can be used. The damping time should be shorter than the characteristic decoherence time, which can be strongly affected by the interplay of different intensity effects (e.g., space charge and impedances). This thesis describes the development of the analytical models that explain decoherence and emittance growth with chromaticity, space charge, and image charges within the first synchrotron period. The pulsed response function including intensity effects was derived from the model for beam transfer functions. For a coasting beam, the two- dimensional model shows that space charge slows down and above intensity threshold suppresses decoherence. These predictions were confirmed by particle tracking simulations with self-consistent space charge fields. Additionally, halo buildup and losses during decoherence were observed in simulations. These effects were successfully interpreted using a non self-consistent particle-core model. The two-dimensional model was extended to the bunched beams. The simulation results reproduce the analytical predictions. The intensity threshold of decoherence suppression is higher in comparison to a coasting beam, image charges can restore decoherence. In the present work dedicated experiments were performed in the SIS18 synchrotron at GSI Darmstadt and the results were compared with simulations and analytical predictions. The contribution of nonlinearities and image charges is negligible while chromaticity and space charge dominate decoherence. To study the damping efficiency of TFS, a comprehensive TFS module was
DEFF Research Database (Denmark)
Gülay, Arda; Pellicer i Nàcher, Carles; Mutlu, Ayten Gizem
diversity than the bioreactors treating synthetic wastewaters inferred from observed OTUs0.03, Chao1, Shannon index and Phylogenetic distance calculations. Differences in total microbial diversity agreed with the ecological theory concerning the positive correlation between substrate complexity...
Transport description of damped nuclear reactions
International Nuclear Information System (INIS)
Randrup, J.
1984-01-01
This lecture series is concerned with the transport description of damped nuclear reactions. Part 1 is an elementary introduction to the general transport theory of nuclear dynamics. It can be read without any special knowledge of the field, although basic quantum mechanics is required for the formal derivation of the general expressions for the transport coefficients. The results can also be used in a wider context than the present one. Part 2 gives the student an up-to-date orientation about recent progress in the understanding of the angular-momentum variables in damped reactions. The emphasis is here on the qualitative understanding of the physics rather than the, at times somewhat tedious, formal derivations. More detailed presentations are due to be published soon. By necessity entire topics have been omitted. For example, no discussion is given of the calculation of the form factors, and the several instructive applications of the theory to transport of mass and change are not covered at all. For these topics they refer to the literature. It is hoped that the present notes provide a sufficient basis to make the literature on the subject accessible to the student
DEFF Research Database (Denmark)
Lohmann-Jensen, Rasmus; Holsgaard-Larsen, Anders; Emmeluth, Claus
2014-01-01
surgery. The non-tourniquet assisted TKA group will have surgery performed without application of a tourniquet. The primary aim is to compare tourniquet assisted to non-tourniquet assisted TKA on patient-reported physical function (KOOS-ADL). The secondary aim is to compare post-surgery pain, function...... in sports and recreation, quality of life, and performance-based physical function. The explorative outcomes include; use of pain medication, single-fiber muscle damage, and changes in mechanical muscle function. The primary endpoint will be at 3-months following surgical treatment, and the time...... randomized clinical trial comparing the efficacy of tourniquet assisted TKA on patient-reported physical function supported by a range of performance-based secondary outcome measures. As such it will provide high quality evidence that may help determine whether tourniquet should be used in future TKA...
Bounce-harmonic Landau Damping of Plasma Waves
Anderegg, Francois
2015-11-01
We present measurement of plasma wave damping, spanning the temperature regimes of direct Landau damping, bounce-harmonic Landau damping, inter-species drag damping, and viscous damping. Direct Landau damping is dominant at high temperatures, but becomes negligible as v vph / 5 . The measurements are conducted in trapped pure ion plasmas contained in Penning-Malmberg trap, with wave-coherent LIF diagnostics of particle velocities. Our focus is on bounce harmonics damping, controlled by an applied ``squeeze'' potential, which generates harmonics in the wave potential and in the particle dynamics. A particle moving in z experiences a non-sinusoidal mode potential caused by the squeeze, producing high spatial harmonics with lower phase velocity. These harmonics are Landau damped even when the mode phase velocity vph is large compared to the thermal velocity v , since the nth harmonic is resonant with a particle bouncing at velocity vb =vph / n . Here we increase the bounce harmonics through applied squeeze potential; but some harmonics are always present in finite length systems. For our centered squeeze geometry, theory shows that only odd harmonics are generated, and predicts the Landau damping rate from vph / n . Experimentally, the squeeze potential increases the wave damping and reduces its frequency. The frequency shift occurs because the squeeze potential reduces the number of particle where the mode velocity is the largest, therefore reducing the mode frequency. We observe an increase in the damping proportional to Vs2,and a frequency reduction proportional to Vs , in quantitative agreement with theory. Wave-coherent laser induced fluorescence allows direct observation of bounce resonances on the particle distribution, here predominantly at vph / 3 . A clear increase of the bounce harmonics is visible on the particle distribution when the squeeze potential is applied. Supported by NSF Grant PHY-1414570, and DOE Grants DE-SC0002451 and DE-SC0008693.
International Nuclear Information System (INIS)
Lin Lin; Lu Jianfeng; Ying Lexing; Weinan, E
2012-01-01
Kohn–Sham density functional theory is one of the most widely used electronic structure theories. In the pseudopotential framework, uniform discretization of the Kohn–Sham Hamiltonian generally results in a large number of basis functions per atom in order to resolve the rapid oscillations of the Kohn–Sham orbitals around the nuclei. Previous attempts to reduce the number of basis functions per atom include the usage of atomic orbitals and similar objects, but the atomic orbitals generally require fine tuning in order to reach high accuracy. We present a novel discretization scheme that adaptively and systematically builds the rapid oscillations of the Kohn–Sham orbitals around the nuclei as well as environmental effects into the basis functions. The resulting basis functions are localized in the real space, and are discontinuous in the global domain. The continuous Kohn–Sham orbitals and the electron density are evaluated from the discontinuous basis functions using the discontinuous Galerkin (DG) framework. Our method is implemented in parallel and the current implementation is able to handle systems with at least thousands of atoms. Numerical examples indicate that our method can reach very high accuracy (less than 1 meV) with a very small number (4–40) of basis functions per atom.
Butler, J.J.; Park, H.; Barnes, P.Y.; Early, E.A.; Eijk-Olij, C. van; Zoutman, A.E.; Buller-Leeuwen, S. van; Groote Schaarsberg, J.
2002-01-01
The measurement and long-term monitoring of global total ozone by ultraviolet albedo measuring satellite instruments require accurate and precise determination of the Bi-directional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in the pre-launch calibration of those instruments. To assess the ability of laboratories to provide accurate Ultra Violet (UV) diffuse BRDF measurements, a BRDF measurement comparison was initiated by the NASA Total Ozone Mapping Spectrom...
Directory of Open Access Journals (Sweden)
Roberto Berretta
2016-06-01
Conclusion: Our study confirmed that pelvic posterior exenteration associated with retrograde radical hysterectomy represents the safest radical surgical approach to advanced ovarian cancer, which permits preservation of the pelvic autonomic nerve plexus and, therefore, bladder and colorectal functions.
Foucault pendulum with eddy-current damping of the elliptical motion
Mastner, G.; Vokurka, V.; Maschek, M.; Vogt, E.; Kaufmann, H. P.
1984-10-01
A newly designed Foucault pendulum is described in which the mechanical Charron ring, used throughout in previous designs for damping of the elliptical motion of the pendulum, is replaced by an electromagnetic eddy-current brake, consisting of a permanent magnet attached to the bottom of the bob and a metallic ring. This damping device is very efficient, as it is self-aligning, symmetrical in the damping effect, and never wears out. The permanent magnet is also used, together with a coil assembly and an electronic circuitry, for the dipole-torque drive of the pendulum as well as for accurate stabilization of the amplitude of the swing. A latched time display, controlled by Hall probes activated by the magnet, is used to visualize the Foucault rotation. The pendulum system and its associated electronic circuitry are described in detail. The optimizing of the drive mode is discussed. Measurements of deviations from theoretical value of the Foucault rotation velocity made automatically in a continuous run show a reproducible accuracy of ±1% or better in individual 360° rotations during the summer months. The quality factor of the pendulum as mechanical resonator was measured as a function of the amplitude in the presence of the eddy-current damping ring.
Fundamental Design Principles of Linear Collider Damping Rings, with an Application to CLIC
Potier, J P
2000-01-01
Damping Rings for Linear Colliders have to produce very small normalised emittances at a high repetition rate. A previous paper presented analytical expressions for the equilibrium emittance of an arc cell as a function of the deflection angle per dipole. In addition, an expression for the lattice parameters providing the minimum emittance, and a strategy to stay close to this, were proposed. This analytical approach is extended to the detailed design of Damping Rings, taking into account the straight sections and the damping wigglers. Complete rings, including wiggler and injection insections, were modelled with the MAD [1] program, and their performance was found to be in good agreement with the analytical calculation. With such an approach it is shown that a Damping Ring corresponding to the Compact Linear Collider (CLIC) parameters at 0.5 and 1 TeV centre-of-mass energy, and tunable for two different sets of emittance and injection repetition rate, can be designed using the same ring layout.
Directory of Open Access Journals (Sweden)
Zhanpeng Fang
2015-01-01
Full Text Available A topology optimization method is proposed to minimize the resonant response of plates with constrained layer damping (CLD treatment under specified broadband harmonic excitations. The topology optimization problem is formulated and the square of displacement resonant response in frequency domain at the specified point is considered as the objective function. Two sensitivity analysis methods are investigated and discussed. The derivative of modal damp ratio is not considered in the conventional sensitivity analysis method. An improved sensitivity analysis method considering the derivative of modal damp ratio is developed to improve the computational accuracy of the sensitivity. The evolutionary structural optimization (ESO method is used to search the optimal layout of CLD material on plates. Numerical examples and experimental results show that the optimal layout of CLD treatment on the plate from the proposed topology optimization using the conventional sensitivity analysis or the improved sensitivity analysis can reduce the displacement resonant response. However, the optimization method using the improved sensitivity analysis can produce a higher modal damping ratio than that using the conventional sensitivity analysis and develop a smaller displacement resonant response.
International Nuclear Information System (INIS)
Pereira, Roberto; Arenas, Jorge P.; Zumelzu, Ernesto
2011-01-01
Research highlights: → Contacting measuring methods produce high variability in the results of damping and stiffness. → Damping of a single metal layer may be accurately obtained through the Central Impedance Method. → The Simply-supported Method does not provide realistic results for multilayer beam samples. -- Abstract: This article presents the experimental results of damping loss factor and Young's modulus obtained for stiff and flexible materials through the use of four different methodologies: the Central Impedance Method, the Modified Oberst Method, the Seismic Response Method, and the simply supported beam method. The first three methods are based on the ASTM standard but using different experimental setting and different Frequency Response Functions. The fourth method corresponds to a non-resonant technique used in the characterization of materials at very low frequencies. In this work, the results of damping loss factor and Young's modulus obtained through these four methods are compared, the variability of results is studied and the sensitivity of each technique when facing controlled temperature variations is verified.
Effect of moisture absorption on damping and dynamic stiffness of carbon fiber/epoxy composites
Energy Technology Data Exchange (ETDEWEB)
Zai, Behzad Ahmed; Park, M. K.; Mehboob, Hassan; Ali, Rashid [Myongji University, Yongin (Korea, Republic of); Choi, H. S. [Korean Air Daejeon (Korea, Republic of)
2009-11-15
In this paper, the damping and dynamic stiffness of UHN125C carbon fiber/epoxy composite beam was experimentally measured. The effect of fiber orientation angle and stacking sequences on damping, resonance frequency, and dynamic stiffness was discussed with a focus on the effect of moisture absorption. Dried specimens were immersed in distilled water for a certain period to absorb water for 8, 16, and 24 d, respectively, and the moisture content absorbed in the specimen was measured. Furthermore, using the impact hammer technique, the measurements of dynamic responses were conducted on a cantilever beam specimen with one end clamped by bolts and metal plates. The damping properties in terms of loss factor were approximated by half-power bandwidth technique. The dynamic stiffness was evaluated using resonance frequency as a function of moisture content. The damping increased with the increase of moisture content: however, the dynamic stiffness reduced with the reduction of resonance frequency. The results of the dynamic stiffness were aided by measuring the dynamic strain using DBU-120A strain-indicating software. The increment in the dynamic strain strengthened the results obtained for dynamic stiffness
Dynamic characteristics of a novel damped outrigger system
Tan, Ping; Fang, Chuangjie; Zhou, Fulin
2014-06-01
This paper presents exact analytical solutions for a novel damped outrigger system, in which viscous dampers are vertically installed between perimeter columns and the core of a high-rise building. An improved analytical model is developed by modeling the effect of the damped outrigger as a general rotational spring acting on a Bernoulli-Euler beam. The equivalent rotational spring stiffness incorporating the combined effects of dampers and axial stiffness of perimeter columns is derived. The dynamic stiffness method (DSM) is applied to formulate the governing equation of the damped outrigger system. The accuracy and efficiency are verified in comparison with those obtained from compatibility equations and boundary equations. Parametric analysis of three non-dimensional factors is conducted to evaluate the influences of various factors, such as the stiffness ratio of the core to the beam, position of the damped outrigger, and the installed damping coefficient. Results show that the modal damping ratio is significantly influenced by the stiffness ratio of the core to the column, and is more sensitive to damping than the position of the damped outrigger. The proposed analytical model in combination with DSM can be extended to the study of structures with more outriggers.
Semilinear damped wave equation in locally uniform spaces
Czech Academy of Sciences Publication Activity Database
Michálek, Martin; Pražák, D.; Slavík, J.
2017-01-01
Roč. 16, č. 5 (2017), s. 1673-1695 ISSN 1534-0392 EU Projects: European Commission(XE) 320078 - MATHEF Institutional support: RVO:67985840 Keywords : damped wave equations * nonlinear damping * unbounded domains Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.801, year: 2016 http://www.aimsciences.org/journals/displayArticlesnew.jsp?paperID=14110
Dynamic stability of a lightly damped column trapped by a ...
African Journals Online (AJOL)
In this paper we initiate an analytical approach for determining the dynamic buckling load of a finite viscously damped column acted upon by a harmonically slowly varying explicitly time dependent load. The viscous damping is considered light and the column rests on an elastic foundation that produces a nonlinear ...
Damping and Frequency Shift of Large Amplitude Electron Plasma Waves
DEFF Research Database (Denmark)
Thomsen, Kenneth; Juul Rasmussen, Jens
1983-01-01
The initial evolution of large-amplitude one-dimensional electron waves is investigated by applying a numerical simulation. The initial wave damping is found to be strongly enhanced relative to the linear damping and it increases with increasing amplitude. The temporal evolution of the nonlinear...
Quantum theory of damped harmonic oscillator | Antia | Global ...
African Journals Online (AJOL)
The exact solutions of the Schrödinger equation for damped harmonic oscillator with pulsating mass and modified Caldirola-Kanai Hamiltonian are evaluated. We also investigated the case of under-damped for the two models constructed and the results obtained in both cases do not violate Heisenberg uncertainty principle ...