Influence of initial state distortion in ion-atom collisions

International Nuclear Information System (INIS)

Ciappina, M F; Cravero, W R; Garibotti, C R

2004-01-01

We have studied the influence of initial state distortion in a single ionization by ion impact. We have taken a continuum distorted wave type distortion and by taking up to the first order in its asymptotic series expansion we build an eikonal-spherical distortion. In this way the influence of each term in the transition amplitude can be stated. This approximation can be considered an intermediate one between the eikonal initial state and the continuum distorted wave approaches for initial state distortion. We have computed doubly differential cross sections for helium ionization by protons and highly charged ions at high and intermediate impact energy. We have also discussed the contribution of the different terms in electron energy spectra, specially in the vicinity of ECC peak. Very good agreement is found with the available experimental data

Lattice Distortion Mediated Paramagnetic Relaxation in High-Spin High-Symmetry Molecular Magnets

Science.gov (United States)

Garg, Anupam

1998-08-01

Field-dependent maxima in the relaxation rate of the magnetic molecules Mn12-Ac and Fe8-tacn have commonly been ascribed to some resonant tunneling phenomena. We argue instead that the relaxation is purely due to phonons. The rate maxima arise because of a Jahn-Teller-like distortion caused by the coupling of phonons to degenerate Zeeman levels of the molecule at the top of the barrier. The binding energy of the distorted intermediate states lowers the barrier height and increases the relaxation rate. A nonperturbative calculation of this effect is carried out for a model system. An approximate result for the field variation near a maximum is found to agree reasonably with experiment.

TPC track distortions III: fiat lux

CERN Document Server

Boyko, I; Dydak, F; Elagin, A; Gostkin, M; Guskov, A; Koreshev, V; Nefedov, Y; Nikolaev, K; Veenhof, R; Wotschack, J; Zhemchugov, A

2005-01-01

We present a comprehensive overview and final summary of all four types of static track distortions seen in the HARP TPC, in terms of physical origins, mathematical modelling, and correction algorithms. 'Static'™ distortions are defined as not depending on the event time within the 400 ms long accelerator spill. Calculated static distortions are compared with measurements from cosmic-muon tracks. We characterize track distortions by the r phi residuals of cluster positions with respect to the transverse projection of a helical trajectory constrained by hits in the RPC overlap regions. This method provides a fixed TPC-external reference system (by contrast to the co-moving coordinate system associated with a fit) which solely permits to identify individually, and measure quantitatively, the static TPC track distortions arising from (i) the inhomogeneity of the solenoidal magnetic field, (ii) the inhomogeneity of the electric field from the high-voltage mismatch between the inner and outer TPC field cages, (...

Sonographic ally Detected Architectural Distortion: Clinical Significance

Energy Technology Data Exchange (ETDEWEB)

Kim, Shin Kee; Seo, Bo Kyoung; Yi, Ann; Cha, Sang Hoon; Kim, Baek Hyun; Cho, Kyu Ran; Kim, Young Sik; Son, Gil Soo; Kim, Young Soo; Kim, Hee Young [Korea University Ansan Hospital, Ansan (Korea, Republic of)

2008-12-15

Architectural distortion is a suspicious abnormality for the diagnosis of breast cancer. The aim of this study was to investigate the clinical significance of sonographic ally detected architectural distortion. From January 2006 to June 2008, 20 patients were identified who had sonographic ally detected architectural distortions without a history of trauma or surgery and abnormal mammographic findings related to an architectural distortion. All of the lesions were pathologically verified. We evaluated the clinical and pathological findings and then assessed the clinical significance of the sonographic ally detected architectural distortions. Based on the clinical findings, one (5%) of the 20 patients had a palpable lump and the remaining 19 patients had no symptoms. No patient had a family history of breast cancer. Based on the pathological findings, three (15%) patients had malignancies. The malignant lesions included invasive ductal carcinomas (n = 2) and ductal carcinoma in situ (n = 1). Four (20%) patients had high-risk lesions: atypical ductal hyperplasia (n = 3) and lobular carcinoma in situ (n = 1). The remaining 13 (65%) patients had benign lesions, however, seven (35%) out of 13 patients had mild-risk lesions (three intraductal papillomas, three moderate or florid epithelial hyperplasia and one sclerosing adenosis). Of the sonographic ally detected architectural distortions, 35% were breast cancers or high-risk lesions and 35% were mild-risk lesions. Thus, a biopsy might be needed for an architectural distortion without an associated mass as depicted on breast ultrasound, even though the mammographic findings are normal

Sonographic ally Detected Architectural Distortion: Clinical Significance

International Nuclear Information System (INIS)

Kim, Shin Kee; Seo, Bo Kyoung; Yi, Ann; Cha, Sang Hoon; Kim, Baek Hyun; Cho, Kyu Ran; Kim, Young Sik; Son, Gil Soo; Kim, Young Soo; Kim, Hee Young

2008-01-01

Architectural distortion is a suspicious abnormality for the diagnosis of breast cancer. The aim of this study was to investigate the clinical significance of sonographic ally detected architectural distortion. From January 2006 to June 2008, 20 patients were identified who had sonographic ally detected architectural distortions without a history of trauma or surgery and abnormal mammographic findings related to an architectural distortion. All of the lesions were pathologically verified. We evaluated the clinical and pathological findings and then assessed the clinical significance of the sonographic ally detected architectural distortions. Based on the clinical findings, one (5%) of the 20 patients had a palpable lump and the remaining 19 patients had no symptoms. No patient had a family history of breast cancer. Based on the pathological findings, three (15%) patients had malignancies. The malignant lesions included invasive ductal carcinomas (n = 2) and ductal carcinoma in situ (n = 1). Four (20%) patients had high-risk lesions: atypical ductal hyperplasia (n = 3) and lobular carcinoma in situ (n = 1). The remaining 13 (65%) patients had benign lesions, however, seven (35%) out of 13 patients had mild-risk lesions (three intraductal papillomas, three moderate or florid epithelial hyperplasia and one sclerosing adenosis). Of the sonographic ally detected architectural distortions, 35% were breast cancers or high-risk lesions and 35% were mild-risk lesions. Thus, a biopsy might be needed for an architectural distortion without an associated mass as depicted on breast ultrasound, even though the mammographic findings are normal

Implementation and Application of PSF-Based EPI Distortion Correction to High Field Animal Imaging

Directory of Open Access Journals (Sweden)

Dominik Paul

2009-01-01

Full Text Available The purpose of this work is to demonstrate the functionality and performance of a PSF-based geometric distortion correction for high-field functional animal EPI. The EPI method was extended to measure the PSF and a postprocessing chain was implemented in Matlab for offline distortion correction. The correction procedure was applied to phantom and in vivo imaging of mice and rats at 9.4T using different SE-EPI and DWI-EPI protocols. Results show the significant improvement in image quality for single- and multishot EPI. Using a reduced FOV in the PSF encoding direction clearly reduced the acquisition time for PSF data by an acceleration factor of 2 or 4, without affecting the correction quality.

Distortion of depth perception in virtual environments using stereoscopic displays: quantitative assessment and corrective measures

Science.gov (United States)

Kleiber, Michael; Winkelholz, Carsten

2008-02-01

The aim of the presented research was to quantify the distortion of depth perception when using stereoscopic displays. The visualization parameters of the used virtual reality system such as perspective, haploscopic separation and width of stereoscopic separation were varied. The experiment was designed to measure distortion in depth perception according to allocentric frames of reference. The results of the experiments indicate that some of the parameters have an antithetic effect which allows to compensate the distortion of depth perception for a range of depths. In contrast to earlier research which reported underestimation of depth perception we found that depth was overestimated when using true projection parameters according to the position of the eyes of the user and display geometry.

Experimental Investigation of Inlet Distortion in a Multistage Axial Compressor

Science.gov (United States)

Rusu, Razvan

The primary objective of this research is to present results and methodologies used to study total pressure inlet distortion in a multi-stage axial compressor environment. The study was performed at the Purdue 3-Stage Axial Compressor Facility (P3S) which models the final three stages of a production turbofan engine's high-pressure compressor (HPC). The goal of this study was twofold; first, to design, implement, and validate a circumferentially traversable total pressure inlet distortion generation system, and second, to demonstrate data acquisition methods to characterize the inter-stage total pressure flow fields to study the propagation and attenuation of a one-per-rev total pressure distortion. The datasets acquired for this study are intended to support the development and validation of novel computational tools and flow physics models for turbomachinery flow analysis. Total pressure inlet distortion was generated using a series of low-porosity wire gauze screens placed upstream of the compressor in the inlet duct. The screens are mounted to a rotatable duct section that can be precisely controlled. The P3S compressor features fixed instrumentation stations located at the aerodynamic interface plane (AIP) and downstream and upstream of each vane row. Furthermore, the compressor features individually indexable stator vanes which can be traverse by up to two vane passages. Using a series of coordinated distortion and vane traverses, the total pressure flow field at the AIP and subsequent inter-stage stations was characterized with a high circumferential resolution. The uniformity of the honeycomb carrier was demonstrated by characterizing the flow field at the AIP while no distortion screens where installed. Next, the distortion screen used for this study was selected following three iterations of porosity reduction. The selected screen consisted of a series of layered screens with a 100% radial extent and a 120° circumferential extent. A detailed total

High-resolution polypeptide structure and dynamics in anisotropic environments: The gramicidin channel

Energy Technology Data Exchange (ETDEWEB)

Cross, T.A.; Lee, K.C.; Ketchem, R.R.; Hu, W.; Lazo, N.D.; Huo, S. [Florida State Univ., Tallahassee, FL (United States)

1994-12-01

To understand the details of macromolecular function, high-resolution structural and dynamic detail is essential. The polypeptide fold of the gramicidin channel has been effectively modeled for the past 20 years, yet the functional changes in conductance and channel lifetime associated with amino acid substitutions cannot be predicted. To accomplish this goal, high-resolution electrostatic modeling and the precise orientation of all dipoles are required. Furthermore, an enhanced knowledge of the complex molecular environment of this membrane-bound peptide is needed. An aqueous environment is relatively uniform and achiral. The membrane environment is very heterogenous and chiral. A knowledge of the interactions, specific and nonspecific, between peptide and lipid will aid in developing a better understanding of this environment. To accomplish this goal, it is necessary to study the peptide in an extended lipid bilayer, rather than in a vesicular or micellar form. These latter environments are likely to possess increased dynamics, increased water penetration, and distorted interactions between the polypeptide and membrane surface. To perform NMR studies on bilayer bound peptides, solid state NMR methods are required, and for specific site information, isotopic labels are incorporated using solid phase peptide synthesis.

Distortions of the distribution function of collisionless particles by high-frequency gravitational waves

International Nuclear Information System (INIS)

Vainer, B.V.; Nasel'skii, P.D.

1983-01-01

Equations for the correlation functions of fluctuations in the spectra of relativistic collisionless particles are obtained from the combined system of Einstein's equations and the Vlasov equation. It is shown that the interaction of high-frequency gravitational waves with collisionless particles leads to diffusion of their spectrum in the momentum space. The distortions in the spectrum of the microwave background radiation in a cosmological model with high-frequency gravitational waves are discussed. Bounds are obtained on the spectral characteristics of background gravitational waves

Using visual feedback distortion to alter coordinated pinching patterns for robotic rehabilitation

Directory of Open Access Journals (Sweden)

Brewer Bambi R

2007-05-01

Full Text Available Abstract Background It is common for individuals with chronic disabilities to continue using the compensatory movement coordination due to entrenched habits, increased perception of task difficulty, or personality variables such as low self-efficacy or a fear of failure. Following our previous work using feedback distortion in a virtual rehabilitation environment to increase strength and range of motion, we address the use of visual feedback distortion environment to alter movement coordination patterns. Methods Fifty-one able-bodied subjects participated in the study. During the experiment, each subject learned to move their index finger and thumb in a particular target pattern while receiving visual feedback. Visual distortion was implemented as a magnification of the error between the thumb and/or index finger position and the desired position. The error reduction profile and the effect of distortion were analyzed by comparing the mean total absolute error and a normalized error that measured performance improvement for each subject as a proportion of the baseline error. Results The results of the study showed that (1 different coordination pattern could be trained with visual feedback and have the new pattern transferred to trials without visual feedback, (2 distorting individual finger at a time allowed different error reduction profile from the controls, and (3 overall learning was not sped up by distorting individual fingers. Conclusion It is important that robotic rehabilitation incorporates multi-limb or finger coordination tasks that are important for activities of daily life in the near future. This study marks the first investigation on multi-finger coordination tasks under visual feedback manipulation.

Coulomb Distortion in the Inelastic Regime

Energy Technology Data Exchange (ETDEWEB)

Patricia Solvignon, Dave Gaskell, John Arrington

2009-09-01

The Coulomb distortion effects have been for a long time neglected in deep inelastic scattering for the good reason that the incident energies were very high. But for energies in the range of earlier data from SLAC or at JLab, the Coulomb distortion could have the potential consequence of affecting the A-dependence of the EMC effect and of the longitudinal to transverse virtual photon absorption cross section ratio $R(x,Q^2)$.

Holographic measurement of distortion during laser melting: Additive distortion from overlapping pulses

Science.gov (United States)

Haglund, Peter; Frostevarg, Jan; Powell, John; Eriksson, Ingemar; Kaplan, Alexander F. H.

2018-03-01

Laser - material interactions such as welding, heat treatment and thermal bending generate thermal gradients which give rise to thermal stresses and strains which often result in a permanent distortion of the heated object. This paper investigates the thermal distortion response which results from pulsed laser surface melting of a stainless steel sheet. Pulsed holography has been used to accurately monitor, in real time, the out-of-plane distortion of stainless steel samples melted on one face by with both single and multiple laser pulses. It has been shown that surface melting by additional laser pulses increases the out of plane distortion of the sample without significantly increasing the melt depth. The distortion differences between the primary pulse and subsequent pulses has also been analysed for fully and partially overlapping laser pulses.

Carrier Distortion in Hysteretic Self-Oscillating Class-D Audio Power

DEFF Research Database (Denmark)

Høyerby, Mikkel Christian Kofod; Andersen, Michael A. E.

2009-01-01

An important distortion mechanism in hysteretic self-oscillating (SO) class-D (switch mode) power amplifiers-–carrier distortion-–is analyzed and an optimization method is proposed. This mechanism is an issue in any power amplifier application where a high degree of proportionality between input...... and output is required, such as in audio power amplifiers or xDSL drivers. From an average-mode point of view, carrier distortion is shown to be caused by nonlinear variation of the hysteretic comparator input average voltage with the output average voltage. This easily causes total harmonic distortion...... figures in excess of 0.1–0.2%, inadequate for high-quality audio applications. Carrier distortion is shown to be minimized when the feedback system is designed to provide a triangular carrier (sliding) signal at the input of a hysteretic comparator. The proposed optimization method is experimentally...

Economic choices reveal probability distortion in macaque monkeys.

Science.gov (United States)

Stauffer, William R; Lak, Armin; Bossaerts, Peter; Schultz, Wolfram

2015-02-18

Economic choices are largely determined by two principal elements, reward value (utility) and probability. Although nonlinear utility functions have been acknowledged for centuries, nonlinear probability weighting (probability distortion) was only recently recognized as a ubiquitous aspect of real-world choice behavior. Even when outcome probabilities are known and acknowledged, human decision makers often overweight low probability outcomes and underweight high probability outcomes. Whereas recent studies measured utility functions and their corresponding neural correlates in monkeys, it is not known whether monkeys distort probability in a manner similar to humans. Therefore, we investigated economic choices in macaque monkeys for evidence of probability distortion. We trained two monkeys to predict reward from probabilistic gambles with constant outcome values (0.5 ml or nothing). The probability of winning was conveyed using explicit visual cues (sector stimuli). Choices between the gambles revealed that the monkeys used the explicit probability information to make meaningful decisions. Using these cues, we measured probability distortion from choices between the gambles and safe rewards. Parametric modeling of the choices revealed classic probability weighting functions with inverted-S shape. Therefore, the animals overweighted low probability rewards and underweighted high probability rewards. Empirical investigation of the behavior verified that the choices were best explained by a combination of nonlinear value and nonlinear probability distortion. Together, these results suggest that probability distortion may reflect evolutionarily preserved neuronal processing. Copyright © 2015 Stauffer et al.

Off-shell distortions of multichannel atomic processes

Science.gov (United States)

Barrachina, R. O.; Clauser, C. F.

2017-10-01

Any multichannel problem can be reduced to a succession of two-body events. However, these basic building blocks of many-body theories do not correspond to elastic processes but are off-the-energy-shell. In view of this difficulty, the great majority of the Distorted-Wave models includes a subsidiary approximation where these off-shell terms are arbitrarily forced to lie on the energy shell. At a first glance, since the energy deficiency is negligible for high enough velocities, the on-shell assumption seems to be completely justified. However, for the case of Coulomb interactions, the two-body off-shell distortions have branch-point singularities on the on-shell limit. In this article we demonstrate that these singularities might produce sizeable distortions of multiple scattering amplitudes, mainly when dealing with ion-ion collisions. Finally, we propose a method of including these distortions that might lead to better results that removing them completely.

Limited distortion in LSB steganography

Science.gov (United States)

Kim, Younhee; Duric, Zoran; Richards, Dana

2006-02-01

It is well known that all information hiding methods that modify the least significant bits introduce distortions into the cover objects. Those distortions have been utilized by steganalysis algorithms to detect that the objects had been modified. It has been proposed that only coefficients whose modification does not introduce large distortions should be used for embedding. In this paper we propose an effcient algorithm for information hiding in the LSBs of JPEG coefficients. Our algorithm uses parity coding to choose the coefficients whose modifications introduce minimal additional distortion. We derive the expected value of the additional distortion as a function of the message length and the probability distribution of the JPEG quantization errors of cover images. Our experiments show close agreement between the theoretical prediction and the actual additional distortion.

Evidence of two-channel distortion effects in positronium formation reactions

International Nuclear Information System (INIS)

Macri, P A; Miraglia, J E; Hanssen, J; Fojon, O A; Rivarola, R D

2004-01-01

The formation of ground-state positronium in collisions of positrons on hydrogen-like atoms is considered. In previous theoretical works, two-centre distorted wavefunctions were employed to approximate either the initial or the final channel. Here we report results obtained by means of the eikonal final state continuum distorted wave approximation for which asymptotically correct distorted wavefunctions are used for both the initial and final states of the scattering system. Comparison of the present theoretical total cross sections with experimental data reveals that distortion effects become important in both channels as the impact energy decreases. This work also shows that distorted-wave theories may be extended from their usual domain of high impact energies to lower ones. (letter to the editor)

Evidence of two-channel distortion effects in positronium formation reactions

Energy Technology Data Exchange (ETDEWEB)

Macri, P A [Instituto de AstronomIa y FIsica del Espacio, Consejo Nacional de Investigaciones CientIficas y Tecnicas-Universidad de Buenos Aires, Casilla de Correo 67, Suc. 28, 1428 Buenos Aires (Argentina); Miraglia, J E [Instituto de AstronomIa y FIsica del Espacio, Consejo Nacional de Investigaciones CientIficas y Tecnicas-Universidad de Buenos Aires, Casilla de Correo 67, Suc. 28, 1428 Buenos Aires (Argentina); Hanssen, J [Laboratoire de Physique Moleculaire et des Collisions, Institute de Physique Rue Arago, Tecnopole 2000, Metz (France); Fojon, O A [Instituto de FIsica de Rosario, Consejo Nacional de Investigaciones CientIficas y Tecnicas-Universidad Nacional de Rosario, Av. Pellegrini 250, 2000 Rosario (Argentina); Rivarola, R D [Instituto de FIsica de Rosario, Consejo Nacional de Investigaciones CientIficas y Tecnicas-Universidad Nacional de Rosario, Av. Pellegrini 250, 2000 Rosario (Argentina)

2004-03-28

The formation of ground-state positronium in collisions of positrons on hydrogen-like atoms is considered. In previous theoretical works, two-centre distorted wavefunctions were employed to approximate either the initial or the final channel. Here we report results obtained by means of the eikonal final state continuum distorted wave approximation for which asymptotically correct distorted wavefunctions are used for both the initial and final states of the scattering system. Comparison of the present theoretical total cross sections with experimental data reveals that distortion effects become important in both channels as the impact energy decreases. This work also shows that distorted-wave theories may be extended from their usual domain of high impact energies to lower ones. (letter to the editor)

Anisotropic extinction distortion of the galaxy correlation function

International Nuclear Information System (INIS)

Fang Wenjuan; Hui Lam; Menard, Brice; May, Morgan; Scranton, Ryan

2011-01-01

Similar to the magnification of the galaxies' fluxes by gravitational lensing, the extinction of the fluxes by comic dust, whose existence is recently detected by [B. Menard, R. Scranton, M. Fukugita, and G. Richards, Mon. Not. R. Astron. Soc. 405, 1025 (2010).], also modifies the distribution of a flux-selected galaxy sample. We study the anisotropic distortion by dust extinction to the 3D galaxy correlation function, including magnification bias and redshift distortion at the same time. We find the extinction distortion is most significant along the line of sight and at large separations, similar to that by magnification bias. The correction from dust extinction is negative except at sufficiently large transverse separations, which is almost always opposite to that from magnification bias (we consider a number count slope s>0.4). Hence, the distortions from these two effects tend to reduce each other. At low z (< or approx. 1), the distortion by extinction is stronger than that by magnification bias, but at high z, the reverse holds. We also study how dust extinction affects probes in real space of the baryon acoustic oscillations (BAO) and the linear redshift distortion parameter β. We find its effect on BAO is negligible. However, it introduces a positive scale-dependent correction to β that can be as large as a few percent. At the same time, we also find a negative scale-dependent correction from magnification bias, which is up to percent level at low z, but to ∼40% at high z. These corrections are non-negligible for precision cosmology, and should be considered when testing General Relativity through the scale-dependence of β.

Advantages of the in-situ LTP distortion profile test on high-heat-load mirrors and applications

International Nuclear Information System (INIS)

Qian, S.; Jark, W.; Sostero, G.; Gambitta, A.; Mazzolini, F.; Savoia, A.

1996-01-01

The first in-situ distortion profile measurement of a high heat load mirror by use of the penta-prism LTP is presented. A maximum height distortion of 0.47 micron in tangential direction over a length of 180 mm was measured for an internally water-cooled mirror of a undulator beam line at ELETTRA while exposed to a total emitted power of 600 W (undulator gap 30 mm and current 180 mA). The experiment has an accuracy and repeatability of 0.04 micron. The test schematic and the test equipment are presented. Two measuring methods to scan a penta-prism being installed either outside or inside the vacuum chamber are introduced. Advantages and some possible applications of adopting the penta-prism LTP to make the in-situ profile test are explained

Structural distortions in 5-10 nm silver nanoparticles under high pressure

Energy Technology Data Exchange (ETDEWEB)

Koski, Kristie J.; Kamp, Noelle M.; Kunz, Martin; Knight, Jason K.; Alivisatos, A.P.; Smith, R.K.

2008-10-13

We present experimental evidence that silver nanoparticles in the size range of 5-10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa. We have used x-ray diffraction with a synchrotron light source to investigate pressure-dependent and size-dependent trends in the crystal structure of silver nanoparticles in a hydrostatic medium compressed in a diamond-anvil cell. Results suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. We propose a mechanism for this transition that considers the bond-length distribution in idealized multiply twinned icosahedral particles. To further support this hypothesis, we also show that similar measurements of single-crystal platinum nanoparticles reveal no such distortions.

Basic numerical study on gap influence of residual stress and distortion during high-brightness laser butt welding

International Nuclear Information System (INIS)

Serizawa, Hisashi; Mori, Daiki; Murakawa, Hidekazu

2013-01-01

High-brightness laser such as fiber laser or disk laser is expected to minimize the total heat input energy in welding due to its high beam quality, and the welding residual stress and distortion also seem to be reduced as a result. However, the diameter of high-brightness laser beam is less than 0.6 mm and it is difficult to set the beam position to contact face between two parts because in general there would be a gap due to quality of parts. In this study, in order to reveal the effect of gap on the residual stress and the welding distortion during fiber laser welding, the butt welding of two plates were examined through the thermal elastic-plastic analysis with a new gap element. From the result of thermal analyses, it was found that the homogeneous ellipsoid body could be applicable to model the shape of heat source for the fiber laser and the gap width would not influence the penetration shape when the gap width was changed from 0.1 to 0.25 mm. In addition, the elastic-plastic analyses indicated that the transverse shrinkage slightly increased with increasing the gap width, while this shrinkage without gap was much smaller than that with gap. Also, it was revealed that the welding speed largely affects both the welding residual stress and distortion. Moreover, it was found that the residual stress was almost independent of the jig position, while the position of fixtures slightly affected the transverse shrinkage. (author)

New technique for real-time distortion-invariant multiobject recognition and classification

Science.gov (United States)

Hong, Rutong; Li, Xiaoshun; Hong, En; Wang, Zuyi; Wei, Hongan

2001-04-01

A real-time hybrid distortion-invariant OPR system was established to make 3D multiobject distortion-invariant automatic pattern recognition. Wavelet transform technique was used to make digital preprocessing of the input scene, to depress the noisy background and enhance the recognized object. A three-layer backpropagation artificial neural network was used in correlation signal post-processing to perform multiobject distortion-invariant recognition and classification. The C-80 and NOA real-time processing ability and the multithread programming technology were used to perform high speed parallel multitask processing and speed up the post processing rate to ROIs. The reference filter library was constructed for the distortion version of 3D object model images based on the distortion parameter tolerance measuring as rotation, azimuth and scale. The real-time optical correlation recognition testing of this OPR system demonstrates that using the preprocessing, post- processing, the nonlinear algorithm os optimum filtering, RFL construction technique and the multithread programming technology, a high possibility of recognition and recognition rate ere obtained for the real-time multiobject distortion-invariant OPR system. The recognition reliability and rate was improved greatly. These techniques are very useful to automatic target recognition.

The significance of Good Chair as part of children’s school and home environment in the preventive treatment of body statistics distortions

OpenAIRE

Mirosław Mrozkowiak; Hanna Żukowska

2015-01-01

Mrozkowiak Mirosław, Żukowska Hanna. Znaczenie Dobrego Krzesła, jako elementu szkolnego i domowego środowiska ucznia, w profilaktyce zaburzeń statyki postawy ciała = The significance of Good Chair as part of children’s school and home environment in the preventive treatment of body statistics distortions. Journal of Education, Health and Sport. 2015;5(7):179-215. ISSN 2391-8306. DOI 10.5281/zenodo.19832 http://ojs.ukw.edu.pl/index.php/johs/article/view/2015%3B5%287%29%3A179-215 https:...

Amplifier Distortion

Science.gov (United States)

Keeports, David

2006-12-01

By definition, a high fidelity amplifier's instantaneous output voltage is directly proportional to its instantaneous input voltage. While high fidelity is generally valued in the amplification of recorded music, nonlinearity, also known as distortion, is desirable in the amplification of some musical instruments. In particular, guitar amplifiers exploit nonlinearity to increase both the harmonic content and sustain of a guitar's sound. I will discuss how both modifications in sound result from saturation of triode tubes and transistors. Additionally, I will describe the difference in the symmetry of saturation curves for transistors and tubes and the reason why tube guitar amplifiers are generally considered to be superior to solid-state amplifiers. Finally, I will discuss attempts to use solid-state electronics to replicate the sound of tube amplifiers.

Contribution of Lattice Distortion to Solid Solution Strengthening in a Series of Refractory High Entropy Alloys

Science.gov (United States)

Chen, H.; Kauffmann, A.; Laube, S.; Choi, I.-C.; Schwaiger, R.; Huang, Y.; Lichtenberg, K.; Müller, F.; Gorr, B.; Christ, H.-J.; Heilmaier, M.

2018-03-01

We present an experimental approach for revealing the impact of lattice distortion on solid solution strengthening in a series of body-centered-cubic (bcc) Al-containing, refractory high entropy alloys (HEAs) from the Nb-Mo-Cr-Ti-Al system. By systematically varying the Nb and Cr content, a wide range of atomic size difference as a common measure for the lattice distortion was obtained. Single-phase, bcc solid solutions were achieved by arc melting and homogenization as well as verified by means of scanning electron microscopy and X-ray diffraction. The atomic radii of the alloying elements for determination of atomic size difference were recalculated on the basis of the mean atomic radii in and the chemical compositions of the solid solutions. Microhardness (μH) at room temperature correlates well with the deduced atomic size difference. Nevertheless, the mechanisms of microscopic slip lead to pronounced temperature dependence of mechanical strength. In order to account for this particular feature, we present a combined approach, using μH, nanoindentation, and compression tests. The athermal proportion to the yield stress of the investigated equimolar alloys is revealed. These parameters support the universality of this aforementioned correlation. Hence, the pertinence of lattice distortion for solid solution strengthening in bcc HEAs is proven.

Distortion definition and correction in off-axis systems

Science.gov (United States)

Da Deppo, Vania; Simioni, Emanuele; Naletto, Giampiero; Cremonese, Gabriele

2015-09-01

Off-axis optical configurations are becoming more and more used in a variety of applications, in particular they are the most preferred solution for cameras devoted to Solar System planets and small bodies (i.e. asteroids and comets) study. Off-axis designs, being devoid of central obstruction, are able to guarantee better PSF and MTF performance, and thus higher contrast imaging capabilities with respect to classical on-axis designs. In particular they are suitable for observing extended targets with intrinsic low contrast features, or scenes where a high dynamical signal range is present. Classical distortion theory is able to well describe the performance of the on-axis systems, but it has to be adapted for the off-axis case. A proper way to deal with off-axis distortion definition is thus needed together with dedicated techniques to accurately measure and hence remove the distortion effects present in the acquired images. In this paper, a review of the distortion definition for off-axis systems will be given. In particular the method adopted by the authors to deal with the distortion related issues (definition, measure, removal) in some off-axis instruments will be described in detail.

Analysis of Brown camera distortion model

Science.gov (United States)

Nowakowski, Artur; Skarbek, Władysław

2013-10-01

Contemporary image acquisition devices introduce optical distortion into image. It results in pixel displacement and therefore needs to be compensated for many computer vision applications. The distortion is usually modeled by the Brown distortion model, which parameters can be included in camera calibration task. In this paper we describe original model, its dependencies and analyze orthogonality with regard to radius for its decentering distortion component. We also report experiments with camera calibration algorithm included in OpenCV library, especially a stability of distortion parameters estimation is evaluated.

[An improved low spectral distortion PCA fusion method].

Science.gov (United States)

Peng, Shi; Zhang, Ai-Wu; Li, Han-Lun; Hu, Shao-Xing; Meng, Xian-Gang; Sun, Wei-Dong

2013-10-01

Aiming at the spectral distortion produced in PCA fusion process, the present paper proposes an improved low spectral distortion PCA fusion method. This method uses NCUT (normalized cut) image segmentation algorithm to make a complex hyperspectral remote sensing image into multiple sub-images for increasing the separability of samples, which can weaken the spectral distortions of traditional PCA fusion; Pixels similarity weighting matrix and masks were produced by using graph theory and clustering theory. These masks are used to cut the hyperspectral image and high-resolution image into some sub-region objects. All corresponding sub-region objects between the hyperspectral image and high-resolution image are fused by using PCA method, and all sub-regional integration results are spliced together to produce a new image. In the experiment, Hyperion hyperspectral data and Rapid Eye data were used. And the experiment result shows that the proposed method has the same ability to enhance spatial resolution and greater ability to improve spectral fidelity performance.

Cyclic Symmetry Finite Element Forced Response Analysis of a Distortion-Tolerant Fan with Boundary Layer Ingestion

Science.gov (United States)

Min, J. B.; Reddy, T. S. R.; Bakhle, M. A.; Coroneos, R. M.; Stefko, G. L.; Provenza, A. J.; Duffy, K. P.

2018-01-01

Accurate prediction of the blade vibration stress is required to determine overall durability of fan blade design under Boundary Layer Ingestion (BLI) distorted flow environments. Traditional single blade modeling technique is incapable of representing accurate modeling for the entire rotor blade system subject to complex dynamic loading behaviors and vibrations in distorted flow conditions. A particular objective of our work was to develop a high-fidelity full-rotor aeromechanics analysis capability for a system subjected to a distorted inlet flow by applying cyclic symmetry finite element modeling methodology. This reduction modeling method allows computationally very efficient analysis using a small periodic section of the full rotor blade system. Experimental testing by the use of the 8-foot by 6-foot Supersonic Wind Tunnel Test facility at NASA Glenn Research Center was also carried out for the system designated as the Boundary Layer Ingesting Inlet/Distortion-Tolerant Fan (BLI2DTF) technology development. The results obtained from the present numerical modeling technique were evaluated with those of the wind tunnel experimental test, toward establishing a computationally efficient aeromechanics analysis modeling tool facilitating for analyses of the full rotor blade systems subjected to a distorted inlet flow conditions. Fairly good correlations were achieved hence our computational modeling techniques were fully demonstrated. The analysis result showed that the safety margin requirement set in the BLI2DTF fan blade design provided a sufficient margin with respect to the operating speed range.

Performance and Adaptive Surge-Preventing Acceleration Prediction of a Turboshaft Engine under Inlet Flow Distortion

Directory of Open Access Journals (Sweden)

Cao Dalu

2017-01-01

Full Text Available The intention of this paper is to research the inlet flow distortion influence on overall performance of turboshaft engine and put forward a method called Distortion Factor Item (DFI to improve the fuel supply plan for surge-preventing acceleration when turboshaft engine suddenly encounters inlet flow distortion. Based on the parallel compressor theory, steady-state and transition-state numerical simulation model of turboshaft engine with sub-compressor model were established for researching the influence of inlet flow distortion on turboshaft engine. This paper made a detailed analysis on the compressor operation from the aspects of performance and stability, and then analyzed the overall performance and dynamic response of the whole engine under inlet flow distortion. Improved fuel supply plan with DFI method was applied to control the acceleration process adaptively when encountering different inlet flow distortion. Several simulation examples about extreme natural environments were calculated to testify DFI method’s environmental applicability. The result shows that the inlet flow distortion reduces the air inflow and decreases the surge margin of compressor, and increase the engine exhaust loss. Encountering inlet flow distortion has many adverse influences such as sudden rotor acceleration, turbine inlet temperature rise and power output reduction. By using improved fuel supply plan with DFI, turboshaft engine above-idle acceleration can avoid surge effectively under inlet flow distortion with environmental applicability.

Tomosynthesis-detected Architectural Distortion: Management Algorithm with Radiologic-Pathologic Correlation.

Science.gov (United States)

Durand, Melissa A; Wang, Steven; Hooley, Regina J; Raghu, Madhavi; Philpotts, Liane E

2016-01-01

As use of digital breast tomosynthesis becomes increasingly widespread, new management challenges are inevitable because tomosynthesis may reveal suspicious lesions not visible at conventional two-dimensional (2D) full-field digital mammography. Architectural distortion is a mammographic finding associated with a high positive predictive value for malignancy. It is detected more frequently at tomosynthesis than at 2D digital mammography and may even be occult at conventional 2D imaging. Few studies have focused on tomosynthesis-detected architectural distortions to date, and optimal management of these distortions has yet to be well defined. Since implementing tomosynthesis at our institution in 2011, we have learned some practical ways to assess architectural distortion. Because distortions may be subtle, tomosynthesis localization tools plus improved visualization of adjacent landmarks are crucial elements in guiding mammographic identification of elusive distortions. These same tools can guide more focused ultrasonography (US) of the breast, which facilitates detection and permits US-guided tissue sampling. Some distortions may be sonographically occult, in which case magnetic resonance imaging may be a reasonable option, both to increase diagnostic confidence and to provide a means for image-guided biopsy. As an alternative, tomosynthesis-guided biopsy, conventional stereotactic biopsy (when possible), or tomosynthesis-guided needle localization may be used to achieve tissue diagnosis. Practical uses for tomosynthesis in evaluation of architectural distortion are highlighted, potential complications are identified, and a working algorithm for management of tomosynthesis-detected architectural distortion is proposed. (©)RSNA, 2016.

Quality Evaluation and Nonuniform Compression of Geometrically Distorted Images Using the Quadtree Distortion Map

Directory of Open Access Journals (Sweden)

Cristina Costa

2004-09-01

Full Text Available The paper presents an analysis of the effects of lossy compression algorithms applied to images affected by geometrical distortion. It will be shown that the encoding-decoding process results in a nonhomogeneous image degradation in the geometrically corrected image, due to the different amount of information associated to each pixel. A distortion measure named quadtree distortion map (QDM able to quantify this aspect is proposed. Furthermore, QDM is exploited to achieve adaptive compression of geometrically distorted pictures, in order to ensure a uniform quality on the final image. Tests are performed using JPEG and JPEG2000 coding standards in order to quantitatively and qualitatively assess the performance of the proposed method.

Cognitive Distortions, Humor Styles, and Depression.

Science.gov (United States)

Rnic, Katerina; Dozois, David J A; Martin, Rod A

2016-08-01

Cognitive distortions are negative biases in thinking that are theorized to represent vulnerability factors for depression and dysphoria. Despite the emphasis placed on cognitive distortions in the context of cognitive behavioural theory and practice, a paucity of research has examined the mechanisms through which they impact depressive symptomatology. Both adaptive and maladaptive styles of humor represent coping strategies that may mediate the relation between cognitive distortions and depressive symptoms. The current study examined the correlations between the frequency and impact of cognitive distortions across both social and achievement-related contexts and types of humor. Cognitive distortions were associated with reduced use of adaptive Affiliative and Self-Enhancing humor styles and increased use of maladaptive Aggressive and Self-Defeating humor. Reduced use of Self-Enhancing humor mediated the relationship between most types of cognitive distortions and depressed mood, indicating that distorted negative thinking may interfere with an individual's ability to adopt a humorous and cheerful outlook on life (i.e., use Self-Enhancing humor) as a way of regulating emotions and coping with stress, thereby resulting in elevated depressive symptoms. Similarly, Self-Defeating humor mediated the association of the social impact of cognitive distortions with depression, such that this humor style may be used as a coping strategy for dealing with distorted thinking that ultimately backfires and results in increased dysphoria.

Distortion Control during Welding

NARCIS (Netherlands)

Akbari Pazooki, A.M.

2014-01-01

The local material expansion and contraction involved in welding result in permanent deformations or instability i.e., welding distortion. Considerable efforts have been made in controlling welding distortion prior to, during or after welding. Thermal Tensioning (TT) describes a group of in-situ

TPC track distortions IV: post tenebras lux

CERN Document Server

Ammosov, V; Boyko, I; Chelkov, G; Dedovitch, D; Dydak, F; Elagin, A; Gostkin, M; Guskov, A; Koreshev, V; Krumshtein, Z; Nefedov, Y; Nikolaev, K; Wotschack, J; Zhemchugov, A

2007-01-01

We present a comprehensive discussion and summary of static and dynamic track distortions in the HARP TPC in terms of physical origin, mathematical modelling and correction algorithms. `Static' distortions are constant with time, while `dynamic' distortions are distortions that occur only during the 400 ms long accelerator spill. The measurement of dynamic distortions, their mathematical modelling and the correction algorithms build on our understanding of static distortions. In the course of corroborating the validity of our static distortion corrections, their reliability and precision was further improved. Dynamic TPC distortions originate dominantly from the `stalactite' effect: a column of positive-ion charge starts growing at the begin of the accelerator spill, and continues growing with nearly constant velocity out from the sense-wire plane into the active TPC volume. However, the `stalactite' effect is not able to describe the distortions that are present already at the start of the spill and which ha...

Correcting the Chromatic Aberration in Barrel Distortion of Endoscopic Images

Directory of Open Access Journals (Sweden)

Y. M. Harry Ng

2003-04-01

Full Text Available Modern endoscopes offer physicians a wide-angle field of view (FOV for minimally invasive therapies. However, the high level of barrel distortion may prevent accurate perception of image. Fortunately, this kind of distortion may be corrected by digital image processing. In this paper we investigate the chromatic aberrations in the barrel distortion of endoscopic images. In the past, chromatic aberration in endoscopes is corrected by achromatic lenses or active lens control. In contrast, we take a computational approach by modifying the concept of image warping and the existing barrel distortion correction algorithm to tackle the chromatic aberration problem. In addition, an error function for the determination of the level of centroid coincidence is proposed. Simulation and experimental results confirm the effectiveness of our method.

Cosmic microwave background distortions at high frequencies

International Nuclear Information System (INIS)

Peter, W.; Peratt, A.L.

1988-01-01

The authors analyze the deviation of the cosmic background radiation spectrum from the 2.76+-0.02 0 Κ blackbody curve. If the cosmic background radiation is due to absorption and re-emission of synchrotron radiation from galactic-width current filaments, higher-order synchrotron modes are less thermalized than lower-order modes, causing a distortion of the blackbody curve at higher frequencies. New observations of the microwave background spectrum at short wavelengths should provide an indication of the number of synchrotron modes thermalized in this process. The deviation of the spectrum from that of a perfect blackbody can thus be correlated with astronomical observations such as filament temperatures and electron energies. The results are discussed and compared with the theoretical predictions of other models which assume the presence of intergalactic superconducting cosmic strings

Frequency modulation television analysis: Distortion analysis

Science.gov (United States)

Hodge, W. H.; Wong, W. H.

1973-01-01

Computer simulation is used to calculate the time-domain waveform of standard T-pulse-and-bar test signal distorted in passing through an FM television system. The simulator includes flat or preemphasized systems and requires specification of the RF predetection filter characteristics. The predetection filters are modeled with frequency-symmetric Chebyshev (0.1-db ripple) and Butterworth filters. The computer was used to calculate distorted output signals for sixty-four different specified systems, and the output waveforms are plotted for all sixty-four. Comparison of the plotted graphs indicates that a Chebyshev predetection filter of four poles causes slightly more signal distortion than a corresponding Butterworth filter and the signal distortion increases as the number of poles increases. An increase in the peak deviation also increases signal distortion. Distortion also increases with the addition of preemphasis.

Response Distortion on Personality Tests in Applicants: Comparing High-Stakes to Low-Stakes Medical Settings

Science.gov (United States)

Anglim, Jeromy; Bozic, Stefan; Little, Jonathon; Lievens, Filip

2018-01-01

The current study examined the degree to which applicants applying for medical internships distort their responses to personality tests and assessed whether this response distortion led to reduced predictive validity. The applicant sample (n = 530) completed the NEO Personality Inventory whilst applying for one of 60 positions as first-year…

Generic distortion model for metrology under optical microscopes

Science.gov (United States)

Liu, Xingjian; Li, Zhongwei; Zhong, Kai; Chao, YuhJin; Miraldo, Pedro; Shi, Yusheng

2018-04-01

For metrology under optical microscopes, lens distortion is the dominant source of error. Previous distortion models and correction methods mostly rely on the assumption that parametric distortion models require a priori knowledge of the microscopes' lens systems. However, because of the numerous optical elements in a microscope, distortions can be hardly represented by a simple parametric model. In this paper, a generic distortion model considering both symmetric and asymmetric distortions is developed. Such a model is obtained by using radial basis functions (RBFs) to interpolate the radius and distortion values of symmetric distortions (image coordinates and distortion rays for asymmetric distortions). An accurate and easy to implement distortion correction method is presented. With the proposed approach, quantitative measurement with better accuracy can be achieved, such as in Digital Image Correlation for deformation measurement when used with an optical microscope. The proposed technique is verified by both synthetic and real data experiments.

Factors associated with body image distortion in Korean adolescents

Directory of Open Access Journals (Sweden)

Hyun MY

2014-05-01

Full Text Available Mi-Yeul Hyun,1 Young-Eun Jung,2 Moon-Doo Kim,2 Young-Sook Kwak,2 Sung-Chul Hong,3 Won-Myong Bahk,4 Bo-Hyun Yoon,5 Hye Won Yoon,6 Bora Yoo61College of Nursing, Jeju National University, Jeju, Korea; 2Department of Psychiatry, School of Medicine, Jeju National University, Jeju, Korea; 3Department of Preventive Medicine, School of Medicine, Jeju National University, Jeju, Korea; 4Department of Psychiatry, Yeouido St Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea; 5Department of Psychiatry, Naju National Hospital, Naju, Korea; 6School of Medicine, Jeju National University, Jeju, KoreaPurpose: Body image incorporates cognitive and affective components as well as behaviors related to own body perception. This study evaluated the occurrence of body image distortion and its correlates in Korean adolescents.Methods: In a school-based cross-sectional survey, a total of 2,117 adolescents were recruited. They filled out self-completing questionnaires on body image distortion, eating attitudes, and behaviors (Eating Attitude Test-26 and related factors.Results: Body image distortions were found in 51.8 percent of adolescents. Univariate analyses showed that boys and older adolescents had higher rates of body image distortion. In the multivariate analyses, body image distortion was associated with high risk for eating disorders (odds ratio [OR] =1.69; 95% confidence interval [CI] 1.11–2.58; P=0.015 and being over weight (OR =33.27; 95% CI 15.51–71.35; P<0.001 or obese (OR =9.37; 95% CI 5.06–17.34; P<0.001.Conclusion: These results suggest that body image distortion is relatively common in Korean adolescents, which has implications for adolescents at risk of developing eating disorders.Keywords: body image distortion, high risk for eating disorders, Korean adolescent

Distortion of Local Atomic Structures in Amorphous Ge-Sb-Te Phase Change Materials

Science.gov (United States)

Hirata, A.; Ichitsubo, T.; Guan, P. F.; Fujita, T.; Chen, M. W.

2018-05-01

The local atomic structures of amorphous Ge-Sb-Te phase-change materials have yet to be clarified and the rapid crystal-amorphous phase change resulting in distinct optical contrast is not well understood. We report the direct observation of local atomic structures in amorphous Ge2Sb2Te5 using "local" reverse Monte Carlo modeling dedicated to an angstrom-beam electron diffraction analysis. The results corroborated the existence of local structures with rocksalt crystal-like topology that were greatly distorted compared to the crystal symmetry. This distortion resulted in the breaking of ideal octahedral atomic environments, thereby forming local disordered structures that basically satisfied the overall amorphous structure factor. The crystal-like distorted octahedral structures could be the main building blocks in the formation of the overall amorphous structure of Ge-Sb-Te.

Mode distortion measurements on the Jefferson lab IR FEL

CERN Document Server

Benson, S V; Shinn, M

2002-01-01

We have previously reported on the analytical calculations of mirror distortion in a high-power FEL with a near-concentric cavity. This analysis allowed us to estimate the power level at which the FEL interaction would be affected, though no exact theory of FEL power vs. distortion exists at this point. Recently we have directly measured the mode size and beam quality as a function of power using a resonator with a center wavelength of 5 mu m. The resonator mirrors were calcium fluoride. This particular material exhibits a large amount of distortion for a given power but, due to the negative slope of refractive index vs. temperature, adds almost no optical phase distortion on the laser output. The mode in the cavity can thus be directly calculated from the measurements at the resonator output. The presence of angular jitter produced raw measurements inconsistent with cold cavity expectations. Removing the effects of the angular jitter, we derive results in agreement with cold cavity measurements. The result i...

A review of PFR core distortion experience

International Nuclear Information System (INIS)

Brook, A.J.

1984-01-01

Neutron induced voidage (NIV) swelling and irradiation creep, acting together or individually, produce deformation in core components exposed to a fast neutron flux and can lead to mechanical interaction between them. Today the nature of these processes is reasonably well understood, and reactor designers have two options in attempting to accomodate them: either by employing a flexible free standing design in which contact loadings are low but in which distortion may be high, or more commonly, by some type of restrained core in which inter-component loadings are high, but where distortion is relatively small. The aims of this paper are: a. to describe briefly the various operational limits of core and core component distortion and how they arise, for which a brief description of reactor construction is necessary; b. to outline how the problems of inter-component contact loadings are overcome for the interactive core; c. to describe some other potential problems which arise either from absolute swelling, or from differential swelling between components; of particular relevance here is the problem of contact loadings between absorber rods and their guide tubes; d. to comment on the degree of agreement with, and the feedback provided by, PIE findings; e. to show how the results of the work influence reactor operators and the reload program

Limitations caused by distortion in room impulse response measurements by swept sine technique

DEFF Research Database (Denmark)

Stojic, Branko; Ciric, Dejan; Markovic, Milos

2011-01-01

The significance of a room impulse response implies the requirement that its measurement should have a high level of accuracy in certain applications. One of the common problems in a measurement process is nonlinearity leading to the distortion of a room impulse response. Limitations caused...... domain with or without memory. On the other hand, the distortion in measurements is achieved either by applying the nonlinearity model or by using higher excitation level and a loudspeaker with a highly nonlinear characteristic. The results show that the most of distortion energy is located in the non...

Guessing and compression subject to distortion

OpenAIRE

Hanawal, Manjesh Kumar; Sundaresan, Rajesh

2010-01-01

The problem of guessing a random string is revisited. The relation-ship between guessing without distortion and compression is extended to the case when source alphabet size is countably in¯nite. Further, similar relationship is established for the case when distortion allowed by establishing a tight relationship between rate distortion codes and guessing strategies.

An Improved Distortion Operator for Insurance Risks

Institute of Scientific and Technical Information of China (English)

GAO Jian-wei; QIU Wan-hua

2002-01-01

This paper reviews the distortion function approach developed in the actuarial literature for insurance risks. The main aim of this paper is to derive an extensive distortion operator, and to propose a new premium principle based on this extensive distortion operator. Furthermore, the non-robustness of general distortion operator is also discussed. Examples are provided using Bernoulli, Pareto, Lognormal and Gamma distribution assumptions.

Audible Aliasing Distortion in Digital Audio Synthesis

Directory of Open Access Journals (Sweden)

J. Schimmel

2012-04-01

Full Text Available This paper deals with aliasing distortion in digital audio signal synthesis of classic periodic waveforms with infinite Fourier series, for electronic musical instruments. When these waveforms are generated in the digital domain then the aliasing appears due to its unlimited bandwidth. There are several techniques for the synthesis of these signals that have been designed to avoid or reduce the aliasing distortion. However, these techniques have high computing demands. One can say that today's computers have enough computing power to use these methods. However, we have to realize that today’s computer-aided music production requires tens of multi-timbre voices generated simultaneously by software synthesizers and the most of the computing power must be reserved for hard-disc recording subsystem and real-time audio processing of many audio channels with a lot of audio effects. Trivially generated classic analog synthesizer waveforms are therefore still effective for sound synthesis. We cannot avoid the aliasing distortion but spectral components produced by the aliasing can be masked with harmonic components and thus made inaudible if sufficient oversampling ratio is used. This paper deals with the assessment of audible aliasing distortion with the help of a psychoacoustic model of simultaneous masking and compares the computing demands of trivial generation using oversampling with those of other methods.

Volterra Series Based Distortion Effect

DEFF Research Database (Denmark)

Agerkvist, Finn T.

2010-01-01

A large part of the characteristic sound of the electric guitar comes from nonlinearities in the signal path. Such nonlinearities may come from the input- or output-stage of the amplier, which is often equipped with vacuum tubes or a dedicated distortion pedal. In this paper the Volterra series...... expansion for non linear systems is investigated with respect to generating good distortion. The Volterra series allows for unlimited adjustment of the level and frequency dependency of each distortion component. Subjectively relevant ways of linking the dierent orders are discussed....

Interliminal Design: Understanding cognitive heuristics to mitigate design distortion

Directory of Open Access Journals (Sweden)

Andrew McCollough

2014-12-01

Full Text Available Cognitive heuristics are mental shortcuts adapted over time to enable rapid interpretation of our complex environment. They are intrinsic to human cognition and resist modification. Heuristics applied outside the context to which they are best suited are termed cognitive bias, and are the cause of systematic errors in judgment and reasoning. As both a cognitive and intuitive discipline, design by individuals is vulnerable to context-inappropriate heuristic usage. Designing in groups can act positively to counterbalance these tendencies, but is subject to heuristic misuse and biases particular to social environments. Mismatch between desired and actual outcomes– termed here, design distortion – occurs when such usage goes unnoticed and unaddressed, and can affect multiple dimensions of a system. We propose a methodology, interliminal design, emerging from the Program in Collaborative Design at Pacific Northwest College of Art, to specifically address the influence of cognitive heuristics in design. This adaptive approach involves reflective, dialogic, inquiry-driven practices intended to increase awareness of heuristic usage, and identify aspects of the design process vulnerable to misuse on both individual and group levels. By facilitating the detection and mitigation of potentially costly errors in judgment and decision-making that create distortion, such metacognitive techniques can meaningfully improve design.

Mixed-Signal Architectures for High-Efficiency and Low-Distortion Digital Audio Processing and Power Amplification

Directory of Open Access Journals (Sweden)

Pierangelo Terreni

2010-01-01

Full Text Available The paper addresses the algorithmic and architectural design of digital input power audio amplifiers. A modelling platform, based on a meet-in-the-middle approach between top-down and bottom-up design strategies, allows a fast but still accurate exploration of the mixed-signal design space. Different amplifier architectures are configured and compared to find optimal trade-offs among different cost-functions: low distortion, high efficiency, low circuit complexity and low sensitivity to parameter changes. A novel amplifier architecture is derived; its prototype implements digital processing IP macrocells (oversampler, interpolating filter, PWM cross-point deriver, noise shaper, multilevel PWM modulator, dead time compensator on a single low-complexity FPGA while off-chip components are used only for the power output stage (LC filter and power MOS bridge; no heatsink is required. The resulting digital input amplifier features a power efficiency higher than 90% and a total harmonic distortion down to 0.13% at power levels of tens of Watts. Discussions towards the full-silicon integration of the mixed-signal amplifier in embedded devices, using BCD technology and targeting power levels of few Watts, are also reported.

Psychological Vulnerability and Problem Gambling: The Mediational Role of Cognitive Distortions.

Science.gov (United States)

Lévesque, David; Sévigny, Serge; Giroux, Isabelle; Jacques, Christian

2018-01-03

Despite numerous studies demonstrating the influence of cognitive distortions on gambling problem severity, empirical data regarding the role of psychological vulnerability on the latter is limited. Hence, this study assesses the mediating effect of cognitive distortions between psychological vulnerability (personality and mood), and gambling problem severity. It also verifies whether the relationships between these variables differs according to the preferred gambling activity. The sample is composed of 272 male gamblers [191 poker players; 81 video lottery terminal (VLT) players] aged between 18 and 82 years (M = 35.2). Bootstrap analysis results revealed that cognitive distortions mediate the effect of narcissism on gambling problem severity for both groups. The level of depression for VLT players significantly predicted gambling problem severity, both directly and indirectly via the mediating effect of cognitive distortions. Mediation analyses also indicated that narcissism had an indirect impact on problem gambling through cognitive distortions for both groups. These findings suggest that certain vulnerabilities related to personality and mood may influence cognitive distortion intensity and gambling problem severity. In addition, psychological vulnerabilities could differ based on preferred gambling activity. These results may be useful for prevention policies, identifying high risk gamblers and planning psychological interventions.

Spectral Distortion in Lossy Compression of Hyperspectral Data

Directory of Open Access Journals (Sweden)

Bruno Aiazzi

2012-01-01

Full Text Available Distortion allocation varying with wavelength in lossy compression of hyperspectral imagery is investigated, with the aim of minimizing the spectral distortion between original and decompressed data. The absolute angular error, or spectral angle mapper (SAM, is used to quantify spectral distortion, while radiometric distortions are measured by maximum absolute deviation (MAD for near-lossless methods, for example, differential pulse code modulation (DPCM, or mean-squared error (MSE for lossy methods, for example, spectral decorrelation followed by JPEG 2000. Two strategies of interband distortion allocation are compared: given a target average bit rate, distortion may be set to be constant with wavelength. Otherwise, it may be allocated proportionally to the noise level of each band, according to the virtually lossless protocol. Comparisons with the uncompressed originals show that the average SAM of radiance spectra is minimized by constant distortion allocation to radiance data. However, variable distortion allocation according to the virtually lossless protocol yields significantly lower SAM in case of reflectance spectra obtained from compressed radiance data, if compared with the constant distortion allocation at the same compression ratio.

The effect of inlet distorted flow on steady and unsteady performance of a centrifugal compressor

International Nuclear Information System (INIS)

Park, Jae Hyoung; Kang, Shin Hyoung

2005-01-01

Effects of inlet distorted flow on performance, stall and surge are experimentally investigated for a high-speed centrifugal compressor. Tested results for the distorted inlet flow cases are compared with the result of the undistorted one. The performance of compressor is slightly deteriorated due to the inlet distortion. The inlet distortion does not affect the number of stall cell and the propagation velocity. It also does not change stall inception flow rate. However, as the distortion increases, stall starts at the higher flow rate for low speed at the lower flow rate for high speed. For 50,000 rpm stall occurs as the flow rate decreases, however disappears for the smaller flow rate. This is due to the interaction of surge and stall. After the stall and surge interact, the number of stall cell decreases

Accuracy evaluation of optical distortion calibration by digital image correlation

Science.gov (United States)

Gao, Zeren; Zhang, Qingchuan; Su, Yong; Wu, Shangquan

2017-11-01

Due to its convenience of operation, the camera calibration algorithm, which is based on the plane template, is widely used in image measurement, computer vision and other fields. How to select a suitable distortion model is always a problem to be solved. Therefore, there is an urgent need for an experimental evaluation of the accuracy of camera distortion calibrations. This paper presents an experimental method for evaluating camera distortion calibration accuracy, which is easy to implement, has high precision, and is suitable for a variety of commonly used lens. First, we use the digital image correlation method to calculate the in-plane rigid body displacement field of an image displayed on a liquid crystal display before and after translation, as captured with a camera. Next, we use a calibration board to calibrate the camera to obtain calibration parameters which are used to correct calculation points of the image before and after deformation. The displacement field before and after correction is compared to analyze the distortion calibration results. Experiments were carried out to evaluate the performance of two commonly used industrial camera lenses for four commonly used distortion models.

Distorted wave models applied to electron emission study in ion-atom collisions at intermediate and high energies

International Nuclear Information System (INIS)

Fainstein, P.D.

1989-01-01

The electron emission from different atoms induced by impact of multicharged bare ions at intermediate and high energies is studied. To perform these studies, the continuum distorted wave-eikonal initial state model is used. With this distorted wave model, analytical expressions are obtained for the transition amplitudes as a function of the transverse momentum transfer for hydrogen targets in an arbitrary initial state and for every any orbital of a multielectronic target represented as a linear combination of Slater type orbitals. With these expressions, the different cross sections which are compared with the experimental data available are numerically calculated. The results obtained for different targets and projectiles and the comparison with other theoretical models and experimental data allows to explain the electron emission spectra and to predict new effects which have not been measured so far. The results of the present work permit to view the ionization process as the evolution of the active electron in the combined field of the target and projectile nuclei. (Author) [es

Simulation of Welding Distortions in Theory and Practice

DEFF Research Database (Denmark)

Birk-Sørensen, Martin; Kierkegaard, Henning

1997-01-01

by an optimised welding order. Welding test samples prove that the constraint of the sample and the time between each pass in a multipass weld affect the magnitude of distortion. Experiments with welding specimens in the form of butt-and fillet welds have been carried out. They show angular deflections as well......In the last few years the use of robot welding processes has increased significatnly. The programming of the robots has until now mainly focused on high efficiency, i.e.high torch rate time, and hence, minimising the inefficient "travelling" time. Together with developing high-performance welding...... due to cutting and welding and parlty in the form of dimensional variation due to human factors. Measurements have been made of the production line for assemblies. The measurements show that distortions related to the multirobot welding are a factor which can rather easily be controlled...

Distortions in Judged Spatial Relations.

Science.gov (United States)

Stevens, Albert

1978-01-01

Distortions in judgments of relative geographical relations were observed, particularly when the locations were in different geographical or political units. Subjects distorted the judged relation to conform with the relation of the superordinate political unit. A model for the hierachical storage of spatial information is presented. (Author/RD)

Analytical evaluation of nonlinear distortion effects on multicarrier signals

CERN Document Server

Araújo, Theresa

2015-01-01

Due to their ability to support reliable high quality of service as well as spectral and power efficiency, multicarrier modulation systems have found increasing use in modern communications services. However, one of the main drawbacks of these systems is their vulnerability to nonlinear distortion effects. Analytical Evaluation of Nonlinear Distortion Effects on Multicarrier Signals details a unified approach to well-known analytical results on memoryless nonlinearities that takes advantage of the Gaussian behavior of multicarrier signals.Sharing new insights into the behavior of nonlinearly d

Stability of a Short Rayleigh Range Laser Resonator with Misaligned or Distorted Mirrors

CERN Document Server

Crooker, Peter P; Colson, William B

2004-01-01

Motivated by the prospect of constructing an FEL with short Rayleigh length in a high-vibration shipboard environment, we have studied the effect of mirror vibration and distortion on the behavior of the fundamental optical mode of a cold-cavity resonator. A tilt or transverse shift of a mirror causes the optical mode to rock sinusoidally about the original resonator axis. A longitudinal mirror shift or a change in the mirror’s radius of curvature causes the beam diameter at a mirror to dilate and contract with successive impacts. Results from both ray-tracing techniques and wavefront propagation simulations are in excellent agreement.

Computational simulation of weld microstructure and distortion by considering process mechanics

Science.gov (United States)

Mochizuki, M.; Mikami, Y.; Okano, S.; Itoh, S.

2009-05-01

Highly precise fabrication of welded materials is in great demand, and so microstructure and distortion controls are essential. Furthermore, consideration of process mechanics is important for intelligent fabrication. In this study, the microstructure and hardness distribution in multi-pass weld metal are evaluated by computational simulations under the conditions of multiple heat cycles and phase transformation. Because conventional CCT diagrams of weld metal are not available even for single-pass weld metal, new diagrams for multi-pass weld metals are created. The weld microstructure and hardness distribution are precisely predicted when using the created CCT diagram for multi-pass weld metal and calculating the weld thermal cycle. Weld distortion is also investigated by using numerical simulation with a thermal elastic-plastic analysis. In conventional evaluations of weld distortion, the average heat input has been used as the dominant parameter; however, it is difficult to consider the effect of molten pool configurations on weld distortion based only on the heat input. Thus, the effect of welding process conditions on weld distortion is studied by considering molten pool configurations, determined by temperature distribution and history.

JET ENGINE INLET DISTORTION SCREEN AND DESCRIPTOR EVALUATION

Directory of Open Access Journals (Sweden)

Jiří Pečinka

2017-02-01

Full Text Available Total pressure distortion is one of the three basic flow distortions (total pressure, total temperature and swirl distortion that might appear at the inlet of a gas turbine engine (GTE during operation. Different numerical parameters are used for assessing the total pressure distortion intensity and extent. These summary descriptors are based on the distribution of total pressure in the aerodynamic interface plane. There are two descriptors largely spread around the world, however, three or four others are still in use and can be found in current references. The staff at the University of Defence decided to compare the most common descriptors using basic flow distortion patterns in order to select the most appropriate descriptor for future department research. The most common descriptors were identified based on their prevalence in widely accessible publications. The construction and use of these descriptors are reviewed in the paper. Subsequently, they are applied to radial, angular, and combined distortion patterns of different intensities and with varied mass flow rates. The tests were performed on a specially designed test bench using an electrically driven standalone industrial centrifugal compressor, sucking air through the inlet of a TJ100 small turbojet engine. Distortion screens were placed into the inlet channel to create the desired total pressure distortions. Of the three basic distortions, only the total pressure distortion descriptors were evaluated. However, both total and static pressures were collected using a multi probe rotational measurement system.

Monte Carlo study of the double and super-exchange model with lattice distortion

Energy Technology Data Exchange (ETDEWEB)

Suarez, J R; Vallejo, E; Navarro, O [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, 04510 Mexico D. F. (Mexico); Avignon, M, E-mail: jrsuarez@iim.unam.m [Institut Neel, Centre National de la Recherche Scientifique (CNRS) and Universite Joseph Fourier, BP 166, 38042 Grenoble Cedex 9 (France)

2009-05-01

In this work a magneto-elastic phase transition was obtained in a linear chain due to the interplay between magnetism and lattice distortion in a double and super-exchange model. It is considered a linear chain consisting of localized classical spins interacting with itinerant electrons. Due to the double exchange interaction, localized spins tend to align ferromagnetically. This ferromagnetic tendency is expected to be frustrated by anti-ferromagnetic super-exchange interactions between neighbor localized spins. Additionally, lattice parameter is allowed to have small changes, which contributes harmonically to the energy of the system. Phase diagram is obtained as a function of the electron density and the super-exchange interaction using a Monte Carlo minimization. At low super-exchange interaction energy phase transition between electron-full ferromagnetic distorted and electron-empty anti-ferromagnetic undistorted phases occurs. In this case all electrons and lattice distortions were found within the ferromagnetic domain. For high super-exchange interaction energy, phase transition between two site distorted periodic arrangement of independent magnetic polarons ordered anti-ferromagnetically and the electron-empty anti-ferromagnetic undistorted phase was found. For this high interaction energy, Wigner crystallization, lattice distortion and charge distribution inside two-site polarons were obtained.

Distortional Modes of Thin-Walled Beams

DEFF Research Database (Denmark)

Jönsson, Jeppe; Andreassen, Michael Joachim

2009-01-01

The classic thin-walled beam theory for open and closed cross-sections can be generalized by including distortional displacement modes. The introduction of additional displacement modes leads to coupled differential equations, which seems to have prohibited the use of exact shape functions...... in the modelling of coupled torsion and distortion. However, if the distortional displacement modes are chosen as those which decouple the differential equations as in non proportionally damped modal dynamic analysis then it may be possible to use exact shape functions and perform analysis on a reduced problem....... In the recently developed generalized beam theory (GBT) the natural distortional displacement modes are determined on the basis of a quadratic eigenvalue problem. However, as in linear modal dynamic analysis of proportionally damped structures this problem has been solved approximately using linear eigenvalue...

Electromagnetic hammer removes weld distortions from aluminum tanks

Science.gov (United States)

Schwinghamer, R. J.

1965-01-01

Distortions around weld areas on sheet-aluminum tanks and other structures are removed with a portable electromagnetic hammer. The hammer incorporates a coil that generates a controlled high-energy pulsed magnetic field over localized areas on the metal surface.

Sources of PCR-induced distortions in high-throughput sequencing data sets

Science.gov (United States)

Kebschull, Justus M.; Zador, Anthony M.

2015-01-01

PCR permits the exponential and sequence-specific amplification of DNA, even from minute starting quantities. PCR is a fundamental step in preparing DNA samples for high-throughput sequencing. However, there are errors associated with PCR-mediated amplification. Here we examine the effects of four important sources of error—bias, stochasticity, template switches and polymerase errors—on sequence representation in low-input next-generation sequencing libraries. We designed a pool of diverse PCR amplicons with a defined structure, and then used Illumina sequencing to search for signatures of each process. We further developed quantitative models for each process, and compared predictions of these models to our experimental data. We find that PCR stochasticity is the major force skewing sequence representation after amplification of a pool of unique DNA amplicons. Polymerase errors become very common in later cycles of PCR but have little impact on the overall sequence distribution as they are confined to small copy numbers. PCR template switches are rare and confined to low copy numbers. Our results provide a theoretical basis for removing distortions from high-throughput sequencing data. In addition, our findings on PCR stochasticity will have particular relevance to quantification of results from single cell sequencing, in which sequences are represented by only one or a few molecules. PMID:26187991

Cognitive distortions and gambling near-misses in Internet Gaming Disorder: A preliminary study.

Directory of Open Access Journals (Sweden)

Yin Wu

Full Text Available Increased cognitive distortions (i.e. biased processing of chance, probability and skill are a key psychopathological process in disordered gambling. The present study investigated state and trait aspects of cognitive distortions in 22 individuals with Internet Gaming Disorder (IGD and 22 healthy controls. Participants completed the Gambling Related Cognitions Scale as a trait measure of cognitive distortions, and played a slot machine task delivering wins, near-misses and full-misses. Ratings of pleasure ("liking" and motivation to play ("wanting" were taken following the different outcomes, and gambling persistence was measured after a mandatory phase. IGD was associated with elevated trait cognitive distortions, in particular skill-oriented cognitions. On the slot machine task, the IGD group showed increased "wanting" ratings compared with control participants, while the two groups did not differ regarding their "liking" of the game. The IGD group displayed increased persistence on the slot machine task. Near-miss outcomes did not elicit stronger motivation to play compared to full-miss outcomes overall, and there was no group difference on this measure. However, a near-miss position effect was observed, such that near-misses stopping before the payline were rated as more motivating than near-misses that stopped after the payline, and this differentiation was attenuated in the IGD group, suggesting possible counterfactual thinking deficits in this group. These data provide preliminary evidence for increased incentive motivation and cognitive distortions in IGD, at least in the context of a chance-based gambling environment.

Cognitive distortions and gambling near-misses in Internet Gaming Disorder: A preliminary study.

Science.gov (United States)

Wu, Yin; Sescousse, Guillaume; Yu, Hongbo; Clark, Luke; Li, Hong

2018-01-01

Increased cognitive distortions (i.e. biased processing of chance, probability and skill) are a key psychopathological process in disordered gambling. The present study investigated state and trait aspects of cognitive distortions in 22 individuals with Internet Gaming Disorder (IGD) and 22 healthy controls. Participants completed the Gambling Related Cognitions Scale as a trait measure of cognitive distortions, and played a slot machine task delivering wins, near-misses and full-misses. Ratings of pleasure ("liking") and motivation to play ("wanting") were taken following the different outcomes, and gambling persistence was measured after a mandatory phase. IGD was associated with elevated trait cognitive distortions, in particular skill-oriented cognitions. On the slot machine task, the IGD group showed increased "wanting" ratings compared with control participants, while the two groups did not differ regarding their "liking" of the game. The IGD group displayed increased persistence on the slot machine task. Near-miss outcomes did not elicit stronger motivation to play compared to full-miss outcomes overall, and there was no group difference on this measure. However, a near-miss position effect was observed, such that near-misses stopping before the payline were rated as more motivating than near-misses that stopped after the payline, and this differentiation was attenuated in the IGD group, suggesting possible counterfactual thinking deficits in this group. These data provide preliminary evidence for increased incentive motivation and cognitive distortions in IGD, at least in the context of a chance-based gambling environment.

Detection of chromatic and luminance distortions in natural scenes.

Science.gov (United States)

Jennings, Ben J; Wang, Karen; Menzies, Samantha; Kingdom, Frederick A A

2015-09-01

A number of studies have measured visual thresholds for detecting spatial distortions applied to images of natural scenes. In one study, Bex [J. Vis.10(2), 1 (2010)10.1167/10.2.231534-7362] measured sensitivity to sinusoidal spatial modulations of image scale. Here, we measure sensitivity to sinusoidal scale distortions applied to the chromatic, luminance, or both layers of natural scene images. We first established that sensitivity does not depend on whether the undistorted comparison image was of the same or of a different scene. Next, we found that, when the luminance but not chromatic layer was distorted, performance was the same regardless of whether the chromatic layer was present, absent, or phase-scrambled; in other words, the chromatic layer, in whatever form, did not affect sensitivity to the luminance layer distortion. However, when the chromatic layer was distorted, sensitivity was higher when the luminance layer was intact compared to when absent or phase-scrambled. These detection threshold results complement the appearance of periodic distortions of the image scale: when the luminance layer is distorted visibly, the scene appears distorted, but when the chromatic layer is distorted visibly, there is little apparent scene distortion. We conclude that (a) observers have a built-in sense of how a normal image of a natural scene should appear, and (b) the detection of distortion in, as well as the apparent distortion of, natural scene images is mediated predominantly by the luminance layer and not chromatic layer.

Prediction of transmission distortion for wireless video communication: analysis.

Science.gov (United States)

Chen, Zhifeng; Wu, Dapeng

2012-03-01

Transmitting video over wireless is a challenging problem since video may be seriously distorted due to packet errors caused by wireless channels. The capability of predicting transmission distortion (i.e., video distortion caused by packet errors) can assist in designing video encoding and transmission schemes that achieve maximum video quality or minimum end-to-end video distortion. This paper is aimed at deriving formulas for predicting transmission distortion. The contribution of this paper is twofold. First, we identify the governing law that describes how the transmission distortion process evolves over time and analytically derive the transmission distortion formula as a closed-form function of video frame statistics, channel error statistics, and system parameters. Second, we identify, for the first time, two important properties of transmission distortion. The first property is that the clipping noise, which is produced by nonlinear clipping, causes decay of propagated error. The second property is that the correlation between motion-vector concealment error and propagated error is negative and has dominant impact on transmission distortion, compared with other correlations. Due to these two properties and elegant error/distortion decomposition, our formula provides not only more accurate prediction but also lower complexity than the existing methods.

Ultrasonographic Findings of Mammographic Architectural Distortion

International Nuclear Information System (INIS)

Ma, Jeong Hyun; Kang, Bong Joo; Cha, Eun Suk; Hwangbo, Seol; Kim, Hyeon Sook; Park, Chang Suk; Kim, Sung Hun; Choi, Jae Jeong; Chung, Yong An

2008-01-01

To review the sonographic findings of various diseases showing architectural distortion depicted under mammography. We collected and reviewed architectural distortions observed under mammography at our health institution between 1 March 2004, and 28 February 2007. We collected 23 cases of sonographically-detected mammographic architectural distortions that confirmed lesions after surgical resection. The sonographic findings of mammographic architectural distortion were analyzed by use of the BI-RADS lexicon for shape, margin, lesion boundary, echo pattern, posterior acoustic feature and orientation. There were variable diseases that showed architectural distortion depicted under mammography. Fibrocystic disease was the most common presentation (n = 6), followed by adenosis (n = 2), stromal fibrosis (n = 2), radial scar (n = 3), usual ductal hyperplasia (n = 1), atypical ductal hyperplasia (n = 1) and mild fibrosis with microcalcification (n = 1). Malignant lesions such as ductal carcinoma in situ (DCIS) (n = 2), lobular carcinoma in situ (LCIS) (n = 2), invasive ductal carcinoma (n = 2) and invasive lobular carcinoma (n = 1) were observed. As observed by sonography, shape was divided as irregular (n = 22) and round (n = 1). Margin was divided as circumscribed (n = 1), indistinct (n = 7), angular (n = 1), microlobulated (n = 1) and sipculated (n = 13). Lesion boundary was divided as abrupt interface (n = 11) and echogenic halo (n = 12). Echo pattern was divided as hypoechoic (n = 20), anechoic (n = 1), hyperechoic (n = 1) and isoechoic (n = 1). Posterior acoustic feature was divided as posterior acoustic feature (n = 7), posterior acoustic shadow (n = 15) and complex posterior acoustic feature (n = 1). Orientation was divided as parallel (n = 12) and not parallel (n = 11). There were no differential sonographic findings between benign and malignant lesions. This study presented various sonographic findings of mammographic architectural distortion and that it is

Distortional Mechanics of Thin-Walled Structural Elements

DEFF Research Database (Denmark)

Andreassen, Michael Joachim

In several industries such as civil, mechanical, and aerospace, thin-walled structures are often used due to the high strength and effective use of the materials. Because of the increased consumption there has been increasing focus on optimizing and more detailed calculations. However, finely...... number of degrees of freedom. This means that the classical Vlasov thin-walled beam theory for open and closed cross sections is generalized as part of a semi-discretization process by including distortional displacement fields. A novel finite-element-based displacement approach is used in combination...... by discretization of the cross section are now solved analytically and the formulation is valid without special attention and approximation also for closed single or multi-cell cross sections. Furthermore, the found eigenvalues have clear mechanical meaning, since they represent the attenuation of the distortional...

Components of segregation distortion in Drosophila melanogaster

International Nuclear Information System (INIS)

Ganetzky, B.

1977-01-01

The segregation distorter (SD) complex is a naturally occurring meiotic drive system with the property that males heterozygous for an SD-bearing chromosome 2 and an SD+-bearing homolog transmit the SD-bearing chromosome almost exclusively. This distorted segregation is the consequence of an induced dysfunction of those sperm that receive the SD+ homolog. From previous studies, two loci have been implicated in this phenomenon: the Sd locus which is required to produce distortion, and the Responder (Rsp) locus that is the site at which Sd acts. There are two allelic alternatives of Rsp-sensitive (Rsp/sup sens/) and insensitive (Rsp/sup ins/); a chromosome carrying Rsp/sup ins/ is not distorted by SD. In the present study, the function and location of each of these elements was examined by a genetic and cytological characterization of x-ray-induced mutations at each locus. The results indicate the following: the Rsp locus is located in the proximal heterochromatin of 2R; a deletion for the Rsp locus renders a chromosome insensitive to distortion; the Sd locus is located to the left of pr (2-54.5), in the region from 37D2-D7 to 38A6-B2 of the salivary chromosome map; an SD chromosome deleted for Sd loses its ability to distort; there is another important component of the SD system, E(SD), in or near the proximal heterochromatin of 2L, that behaves as a strong enhancer of distortion. The results of these studies allow a reinterpretation of results from earlier analyses of the SD system and serve to limit the possible mechanisms to account for segregation distortion

TPC track distortions: correction maps for magnetic and static electric inhomogeneities

CERN Document Server

Dydak, F; Nefedov, Y

2003-01-01

Inhomogeneities of the magnetic and electric fields in the active TPC volume lead to displacements of cluster coordinates, and therefore to track distortions. In case of good data taking conditions, the largest effects are expected from the inhomogeneity of the solenoidal magnetic field, and from a distortion of the electric field arising from a high voltage misalignment between the outer and inner field cages. Both effects are stable over the entire HARP data taking. The displacements are large compared to the azimuthal coordinate resolution but can be corrected with sufficient precision, except at small TPC radius. The high voltage misalignment between the outer and inner field cages is identified as the likely primary cause of sagitta distortions of TPC tracks. The position and the length of the target plays an important role. Based on a detailed modelling of the magnetic and static electric field inhomogeneities, precise correction maps for both effects have been calculated. Predictions from the correctio...

Effects of aspirin on distortion product fine structure: interpreted by the two-source model for distortion product otoacoustic emissions generation.

Science.gov (United States)

Rao, Aparna; Long, Glenis R

2011-02-01

Distortion product otoacoustic emission (DPOAE) fine structure is due to the interaction of two major components coming from different places in the cochlea. One component is generated from the region of maximal overlap of the traveling waves generated by the two primaries and is attributed to nonlinear distortion (nonlinear component). The other component arises predominantly from the tonotopic region of the distortion product and is attributed to linear coherent reflection (reflection component). Aspirin (salicylate) ototoxicity can cause reversible hearing loss and reduces otoacoustic emission generation in the cochlea. The two components are expected to be affected differentially by cochlear health. Changes in DPOAE fine structure were recorded longitudinally in three subjects before, during, and after aspirin consumption. Full data sets were analyzed for two subjects, but only partial data could be analyzed from the third subject. Resulting changes in the two components of DPOAE fine structure revealed variability among subjects and differential effects on the two components. For low-intensity primaries, both components were reduced with the reflection component being more vulnerable. For high-intensity primaries, the nonlinear component showed little or no change, but the reflection component was always reduced.

Centi-pixel accurate real-time inverse distortion correction

CSIR Research Space (South Africa)

De Villiers, Johan P

2008-11-01

Full Text Available Inverse distortion is used to create an undistorted image from a distorted image. For each pixel in the undistorted image it is required to determine which pixel in the distorted image should be used. However the process of characterizing a lens...

The magnetic-distortion probe: velocimetry in conducting fluids.

Science.gov (United States)

Miralles, Sophie; Verhille, Gautier; Plihon, Nicolas; Pinton, Jean-François

2011-09-01

A new type of velocimeter, capable of local velocity measurements in conducting fluids, is introduced. The principle of the "magnetic-distortion probe" is based on the measurement of the induced magnetic field by the flow of a conducting fluid in the vicinity of a localized magnetic field. The new velocimeter has no moving parts, and can be enclosed in a sealed cap, easing the implementation in harsh environments, such as liquid metals. The proposed method allows one to probe both the continuous part and fluctuations of the velocity, the temporal and spatial resolution being linked to the actual geometric configuration of the probe. A prototype probe has been tested in a gallinstan pipe flow and in a fully turbulent flow of liquid gallium generated by the counter rotation of two coaxial impellers in a cylinder. The signals have been compared to a reference potential probe and show very good agreement both for time-averaged velocities and turbulent fluctuations. The prototype is shown to detect motion from a few cm s(-1) to a few m s(-1). Moreover, the use of the magnetic-distortion probe with large-scale applied magnetic field is discussed. © 2011 American Institute of Physics

Presence of a highly efficient binding to bacterial contamination can distort data from binding studies

International Nuclear Information System (INIS)

Balcar, V.J.

1990-01-01

3 HGABA at low concentrations (5-10 nM) was bound by what appeared to be a GABA receptor binding site in bacterial contamination originating from a batch of distilled water. Under experimental conditions similar to those usually employed in 3 HGABA binding studies, the apparent binding displayed a very high specific component and a high efficiency in terms of 3 HGABA bound per mg of protein. The binding was blocked by muscimol but not by isoguvacine, SR95531 and nipecotic acid. These characteristics suggest that the presence of such spurious binding in the experiments using 3H-labeled ligands in brain homogenates may not always be very obvious and, moreover, it can result in subtle, but serious, distortions of data from such studies, which may not be immediately recognized

Simulation of distortion and residual stress in high pressure die casting – modelling and experiments

International Nuclear Information System (INIS)

Hofer, P; Kaschnitz, E; Schumacher, P

2012-01-01

Two individual high-pressure die-casting geometries were developed in order to study the influence of process parameters and different alloys on the distortion behaviour of castings. These geometries were a stress lattice and a V-shaped sample tending to form residual stress due to different wall thickness respectively by a deliberate massive gating system. In the experimental castings the influence of the most important process parameters such as die temperature and die opening time and the cooling regime was examined. The time evolution of process temperatures was measured using thermal imaging. The heat transfer coefficients were adapted to the observed temperature distributions. Castings were produced from the two alloys AlSi12 and AlSi10MnMg. The distortion of the castings was measured by means of a tactile measuring device. For the alloy AlSi10MnMg thermo-physical and thermo-mechanical data were obtained using differential scanning calorimetry, laser flash technique, dilatometry and tensile testing at elevated temperatures. These data were used for modelling the material behaviour of the AlSi10MnMg alloy in the numerical model while for the alloy AlSi12(Fe) literature data were used. Process and stress simulation were conducted using the commercial FEM software ANSYS Workbench. A survey on the results of the comparison between simulation and experiment is given for both alloys.

FSD: Frequency Space Differential measurement of CMB spectral distortions

Science.gov (United States)

Mukherjee, Suvodip; Silk, Joseph; Wandelt, Benjamin D.

2018-04-01

Although the Cosmic Microwave Background agrees with a perfect blackbody spectrum within the current experimental limits, it is expected to exhibit certain spectral distortions with known spectral properties. We propose a new method, Frequency Space Differential (FSD) to measure the spectral distortions in the CMB spectrum by using the inter-frequency differences of the brightness temperature. The difference between the observed CMB temperature at different frequencies must agree with the frequency derivative of the blackbody spectrum, in the absence of any distortion. However, in the presence of spectral distortions, the measured inter-frequency differences would also exhibit deviations from blackbody which can be modeled for known sources of spectral distortions like y & μ. Our technique uses FSD information for the CMB blackbody, y, μ or any other sources of spectral distortions to model the observed signal. Successful application of this method in future CMB missions can provide an alternative method to extract spectral distortion signals and can potentially make it feasible to measure spectral distortions without an internal blackbody calibrator.

Harmonic analysis for the characterization and correction of geometric distortion in MRI.

Science.gov (United States)

Tadic, Tony; Jaffray, David A; Stanescu, Teodor

2014-11-01

Magnetic resonance imaging (MRI) is gaining widespread use in radiation therapy planning, patient setup verification, and real-time guidance of radiation delivery. Successful implementation of these technologies relies on the development of simple and efficient methods to characterize and monitor the geometric distortions arising due to system imperfections and gradient nonlinearities. To this end, the authors present the theory and validation of a novel harmonic approach to the quantification of system-related distortions in MRI. The theory of spatial encoding in MRI is applied to demonstrate that the 3D distortion vector field (DVF) is given by the solution of a second-order boundary value problem (BVP). This BVP is comprised of Laplace's equation and a limited measurement of the distortion on the boundary of a specified region of interest (ROI). An analytical series expansion solving this BVP within a spherical ROI is obtained, and a statistical uncertainty analysis is performed to determine how random errors in the boundary measurements propagate to the ROI interior. This series expansion is then evaluated to obtain volumetric DVF mappings that are compared to reference data obtained on a 3 T full-body scanner. This validation is performed within two spheres of 20 cm diameter (one centered at the scanner origin and the other offset +3 cm along each of the transverse directions). Initially, a high-order mapping requiring measurements at 5810 boundary points is used. Then, after exploring the impact of the boundary sampling density and the effect of series truncation, a reduced-order mapping requiring measurements at 302 boundary points is evaluated. The volumetric DVF mappings obtained from the harmonic analysis are in good agreement with the reference data. Following distortion correction using the high-order mapping, the authors estimate a reduction in the mean distortion magnitude from 0.86 to 0.42 mm and from 0.93 to 0.39 mm within the central and offset

Carrier Distortion in Hysteretic Self-Oscillating Class-D Audio Power:Amplifiers: Analysis and Optimization

OpenAIRE

Høyerby, Mikkel Christian Kofod; Andersen, Michael A. E.

2009-01-01

An important distortion mechanism in hysteretic self-oscillating (SO) class-D (switch mode) power amplifiers-–carrier distortion-–is analyzed and an optimization method is proposed. This mechanism is an issue in any power amplifier application where a high degree of proportionality between input and output is required, such as in audio power amplifiers or xDSL drivers. From an average-mode point of view, carrier distortion is shown to be caused by nonlinear variation of the hysteretic compara...

Impact of loudspeaker nonlinear distortion on personal sound zones

DEFF Research Database (Denmark)

Ma, Xiaohui; J. Hegarty, Patrick; Abildgaard Pedersen, Jan

2018-01-01

Personal sound zone systems aim at creating multiple listening zones within a shared space with minimum interference between zones, but the performance is often poorer than simulations predict and effects of nonlinear distortion are sometimes audible. This paper assesses the impact of nonlinear...... distortion on sound zones through simulations and measurements performed under anechoic conditions. Two sound zones, one bright and one dark, are created with acoustic contrast control using two loudspeaker arrays driven at 250 Hz. Nonlinear distortion is modelled using second or third order nonlinearities....... Simulations show that nonlinear distortion degrades the acoustic contrast, which is confirmed by experimental measurements. The harmonic distortion is audible in the dark zone. Frequency resolved measurements reveal that harmonic distortion contributes to contrast loss, but nonlinear effects...

Radial lens distortion correction with sub-pixel accuracy for X-ray micro-tomography.

Science.gov (United States)

Vo, Nghia T; Atwood, Robert C; Drakopoulos, Michael

2015-12-14

Distortion correction or camera calibration for an imaging system which is highly configurable and requires frequent disassembly for maintenance or replacement of parts needs a speedy method for recalibration. Here we present direct techniques for calculating distortion parameters of a non-linear model based on the correct determination of the center of distortion. These techniques are fast, very easy to implement, and accurate at sub-pixel level. The implementation at the X-ray tomography system of the I12 beamline, Diamond Light Source, which strictly requires sub-pixel accuracy, shows excellent performance in the calibration image and in the reconstructed images.

Expression-dependent susceptibility to face distortions in processing of facial expressions of emotion.

Science.gov (United States)

Guo, Kun; Soornack, Yoshi; Settle, Rebecca

2018-03-05

Our capability of recognizing facial expressions of emotion under different viewing conditions implies the existence of an invariant expression representation. As natural visual signals are often distorted and our perceptual strategy changes with external noise level, it is essential to understand how expression perception is susceptible to face distortion and whether the same facial cues are used to process high- and low-quality face images. We systematically manipulated face image resolution (experiment 1) and blur (experiment 2), and measured participants' expression categorization accuracy, perceived expression intensity and associated gaze patterns. Our analysis revealed a reasonable tolerance to face distortion in expression perception. Reducing image resolution up to 48 × 64 pixels or increasing image blur up to 15 cycles/image had little impact on expression assessment and associated gaze behaviour. Further distortion led to decreased expression categorization accuracy and intensity rating, increased reaction time and fixation duration, and stronger central fixation bias which was not driven by distortion-induced changes in local image saliency. Interestingly, the observed distortion effects were expression-dependent with less deterioration impact on happy and surprise expressions, suggesting this distortion-invariant facial expression perception might be achieved through the categorical model involving a non-linear configural combination of local facial features. Copyright © 2018 Elsevier Ltd. All rights reserved.

Distortion of DNA Origami on Graphene Imaged with Advanced TEM Techniques.

Science.gov (United States)

Kabiri, Yoones; Ananth, Adithya N; van der Torre, Jaco; Katan, Allard; Hong, Jin-Yong; Malladi, Sairam; Kong, Jing; Zandbergen, Henny; Dekker, Cees

2017-08-01

While graphene may appear to be the ultimate support membrane for transmission electron microscopy (TEM) imaging of DNA nanostructures, very little is known if it poses an advantage over conventional carbon supports in terms of resolution and contrast. Microscopic investigations are carried out on DNA origami nanoplates that are supported onto freestanding graphene, using advanced TEM techniques, including a new dark-field technique that is recently developed in our lab. TEM images of stained and unstained DNA origami are presented with high contrast on both graphene and amorphous carbon membranes. On graphene, the images of the origami plates show severe unwanted distortions, where the rectangular shape of the nanoplates is significantly distorted. From a number of comparative control experiments, it is demonstrated that neither staining agents, nor screening ions, nor the level of electron-beam irradiation cause this distortion. Instead, it is suggested that origami nanoplates are distorted due to hydrophobic interaction of the DNA bases with graphene upon adsorption of the DNA origami nanoplates. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural Change Accounting with Labor Market Distortions

OpenAIRE

Wenbiao Cai

2014-01-01

This paper quantifies the relative importance of sectoral productivity and labor market distortions for structural change. I use a model in which labor productivity is the product of TFP and human capital in each sector, but distortions generate wedges in wage per efficiency worker across sectors. I calculate human capital by sector using micro census data, and use the model to infer TFP and distortions such that it replicates structural change in the US, India, Mexico and Brazil between 1960...

Lattice effects in La1-xCaxMnO3 (x=0→1): Relationships between distortions, charge distribution, and magnetism

International Nuclear Information System (INIS)

Booth, C.H.; Bridges, F.; Kwei, G.H.; Lawrence, J.M.; Cornelius, A.L.; Neumeier, J.J.

1998-01-01

X-ray-absorption fine-structure measurements from the Mn and La K edges of samples of La 1-x Ca x MnO 3 (x=0→1) are presented as a function of temperature. In the insulating state, distortions of the Mn-O environment are found to be linear with calcium concentration x. These distortions are consistent with a model where individual Mn 3+ sites have strong Jahn-Teller (JT) distortions while Mn 4+ sites do not, although intermediate distortions are also possible. Comparisons to simulations of various possible bond length distributions show that these distortions are best modeled as a JT distortion, as opposed to charge disproportionation or other models. In the metallic state, at least ∼70% of the distortion is removed. A similar effect is seen in the Mn-Mn bond length distribution. The La-O bond length distribution does not change significantly through the ferromagnetic transition, constraining possible changes in the Mn-O-Mn bond angle to less than 0.5 degree. The changes in the MnO 6 distortion that occur near T c are also present (to a lesser degree) in an insulating sample with x=0.12. The functional relation between the MnO 6 distortions and the magnetization is determined, and compared to transport measurements. copyright 1998 The American Physical Society

Analysis of thermal coal pricing and the coal price distortion in China from the perspective of market forces

International Nuclear Information System (INIS)

Cui, Herui; Wei, Pengbang

2017-01-01

The price of thermal coal has always been the focus of the debate between coal mining industry and electric power industry. The thermal coal price is always lower than other same quality coal, and this phenomenon of thermal coal price distortion has been existing in China for a long time. The distortion coal price can not reflect the external cost and the resource scarcity of coal, which could result in environment deteriorating and inefficient resource allocation. This paper studied the phenomenon of thermal coal price distortion through economic theoretical modeling and empirical cointegration analysis from the perspective of market forces. The results show that thermal coal price is determined by electricity price, the prediction elasticity of a electricity enterprise, price elasticity of demand of electricity, the input prediction elasticity of a electricity enterprise and the price elasticity of supply of thermal coal. The main reason of coal price distortion is the unbalance market force of coal industry and thermal coal generation industry. The distortion rate of coal price is positively related to the market force of electric power industry and negatively related to the industrial concentration of coal industry. - Highlights: • This paper studied thermal coal pricing and the coal price distortion in China. • The main reason of coal price distortion is the unbalance market force. • Thermal coal price is also influenced by electricity price and price elasticity of demand of electricity. • The distortion rate of coal price is negatively related to the industrial concentration of coal industry.

Density distortion within a rotating body

International Nuclear Information System (INIS)

Lanzano, P.

1975-01-01

This paper ascertains the distortion of the density distribution within a self-gravitating body in hydrostatic equilibrium under the influence of rotation. For this purpose, the Poisson equation has been solved by using the undistorted density profile within the Laplacian to obtain the distorted density. The Laplacian has been expressed in terms of a system of curvilinear coordinates for which the equipotential surfaces constitute a family of fundamental surfaces. In performing the requisite algebraic manipulations, the Clairaut and Radau equations developed in a previous paper (Lanzano,1974) were utilized to eliminate the derivatives of the elements pertaining to the equipotential surfaces. The density distortion has been obtained up to third-order terms in a small rotational parameter. (Auth.)

Cognitive Distortions in Depressed Women: Trait, or State Dependent?

Directory of Open Access Journals (Sweden)

Sedat BATMAZ

2015-12-01

Conclusion: The results have revealed that self-criticism, helplessness, hopelessness and preoccupation with danger related distortions had trait-like features, whereas self-blame related distortions were state dependent. This has clinical implications for the psychotherapeutic treatment of cognitive distortions in depression. Specifically, self-criticism related distortions should be managed during cognitive therapy for depression since the other subscales seem rather problematic. [JCBPR 2015; 4(3.000: 147-152

Influence of growth stresses and material properties on distortion of sawn timber - numerical investigation

DEFF Research Database (Denmark)

Johansson, Marie; Ormarsson, Sigurdur

2009-01-01

The board distortion that occurs during the sawing and the drying process causes major problems in the utilisation of sawn timber. The distortion is highly influenced by parameters such as spiral grain angle, modulus of elasticity, shrinkage, growth stresses and sawing pattern. In this study...... a finite element simulation of log sawing and timber drying was performed to study how these parameters interact to affect board distortion. A total of 81 logs with different material combinations were simulated. From each simulated log four boards with different annual ring orientation were studied...

Advanced Machining Toolpath for Low Distortion

Science.gov (United States)

2017-02-28

Advanced Machining Toolpath for Low Distortion FINAL STATUS REPORT Prepared by Brian Becker R&D Technology Manager Third Wave Systems, Inc... Machining Toolpath for Low Distortion December 2016 Contract No.: W911W6-16-P-0044 2 Table of Contents 1.0 EXECUTIVE SUMMARY...2 2.1 Task 1: Collect Details of Machining Lab to Support

A Phase-Controlled Optical Parametric Amplifier Pumped by Two Phase-Distorted Laser Beams

International Nuclear Information System (INIS)

Hong-Yan, Ren; Lie-Jia, Qian; Peng, Yuan; He-Yuan, Zhu; Dian-Yuan, Fan

2010-01-01

We theoretically study the phase characteristic of optical parametric amplification (OPA) or chirped pulse OPA (OPCPA) pumped by two phase-distorted laser beams. In the two-beam-pumped optical parametric amplification (TBOPA), due to spatial walk-off, both of the pump phase distortions will be partly transferred to signal in a single crystal so as to degrade the signal beam-quality, which will be more serious in high-energy OPCPA. An OPA configuration with a walkoff-compensated crystal pair is demonstrated for reducing the signal phase distortion experienced in the first stage and ensuring the signal phase independent of two pump phase distortions through the second crystal, hence maintaining the signal beam-quality. Such a TBOPA is similar to the conventional quantum laser amplifier by means of eliminating its sensitivity to the phase and number of the pump beams

Harmonic analysis for the characterization and correction of geometric distortion in MRI

International Nuclear Information System (INIS)

Tadic, Tony; Stanescu, Teodor; Jaffray, David A.

2014-01-01

Purpose: Magnetic resonance imaging (MRI) is gaining widespread use in radiation therapy planning, patient setup verification, and real-time guidance of radiation delivery. Successful implementation of these technologies relies on the development of simple and efficient methods to characterize and monitor the geometric distortions arising due to system imperfections and gradient nonlinearities. To this end, the authors present the theory and validation of a novel harmonic approach to the quantification of system-related distortions in MRI. Methods: The theory of spatial encoding in MRI is applied to demonstrate that the 3D distortion vector field (DVF) is given by the solution of a second-order boundary value problem (BVP). This BVP is comprised of Laplace’s equation and a limited measurement of the distortion on the boundary of a specified region of interest (ROI). An analytical series expansion solving this BVP within a spherical ROI is obtained, and a statistical uncertainty analysis is performed to determine how random errors in the boundary measurements propagate to the ROI interior. This series expansion is then evaluated to obtain volumetric DVF mappings that are compared to reference data obtained on a 3 T full-body scanner. This validation is performed within two spheres of 20 cm diameter (one centered at the scanner origin and the other offset +3 cm along each of the transverse directions). Initially, a high-order mapping requiring measurements at 5810 boundary points is used. Then, after exploring the impact of the boundary sampling density and the effect of series truncation, a reduced-order mapping requiring measurements at 302 boundary points is evaluated. Results: The volumetric DVF mappings obtained from the harmonic analysis are in good agreement with the reference data. Following distortion correction using the high-order mapping, the authors estimate a reduction in the mean distortion magnitude from 0.86 to 0.42 mm and from 0.93 to 0.39 mm

Phase distortions in sum- and difference-frequency mixing in crystals

International Nuclear Information System (INIS)

Smith, A.V.; Bowers, M.S.

1995-01-01

We show that if two waves are incident on a quadratically nonlinear crystal, with the third wave generated entirely within the crystal, a phase-velocity mismatch (Δk ≠ 0) leads to intensity-dependent phase shifts of the generated wave only if there is walk-off, linear absorption, or significant diffraction of at least one of the waves as well as significant energy exchange among the waves. The result is frequency broadening and wave-front distortion of the generated wave. Although the induced phase distortions are usually quite small, they may be significant in applications that require high spectral resolution or pointing accuracy

Effects of Visual Feedback Distortion on Gait Adaptation: Comparison of Implicit Visual Distortion Versus Conscious Modulation on Retention of Motor Learning.

Science.gov (United States)

Kim, Seung-Jae; Ogilvie, Mitchell; Shimabukuro, Nathan; Stewart, Trevor; Shin, Joon-Ho

2015-09-01

Visual feedback can be used during gait rehabilitation to improve the efficacy of training. We presented a paradigm called visual feedback distortion; the visual representation of step length was manipulated during treadmill walking. Our prior work demonstrated that an implicit distortion of visual feedback of step length entails an unintentional adaptive process in the subjects' spatial gait pattern. Here, we investigated whether the implicit visual feedback distortion, versus conscious correction, promotes efficient locomotor adaptation that relates to greater retention of a task. Thirteen healthy subjects were studied under two conditions: (1) we implicitly distorted the visual representation of their gait symmetry over 14 min, and (2) with help of visual feedback, subjects were told to walk on the treadmill with the intent of attaining the gait asymmetry observed during the first implicit trial. After adaptation, the visual feedback was removed while subjects continued walking normally. Over this 6-min period, retention of preserved asymmetric pattern was assessed. We found that there was a greater retention rate during the implicit distortion trial than that of the visually guided conscious modulation trial. This study highlights the important role of implicit learning in the context of gait rehabilitation by demonstrating that training with implicit visual feedback distortion may produce longer lasting effects. This suggests that using visual feedback distortion could improve the effectiveness of treadmill rehabilitation processes by influencing the retention of motor skills.

Image Acquisition of Robust Vision Systems to Monitor Blurred Objects in Hazy Smoking Environments

International Nuclear Information System (INIS)

Ahn, Yongjin; Park, Seungkyu; Baik, Sunghoon; Kim, Donglyul; Nam, Sungmo; Jeong, Kyungmin

2014-01-01

Image information in disaster area or radiation area of nuclear industry is an important data for safety inspection and preparing appropriate damage control plans. So, robust vision system for structures and facilities in blurred smoking environments, such as the places of a fire and detonation, is essential in remote monitoring. Vision systems can't acquire an image when the illumination light is blocked by disturbance materials, such as smoke, fog, dust. The vision system based on wavefront correction can be applied to blurred imaging environments and the range-gated imaging system can be applied to both of blurred imaging and darken light environments. Wavefront control is a widely used technique to improve the performance of optical systems by actively correcting wavefront distortions, such as atmospheric turbulence, thermally-induced distortions, and laser or laser device aberrations, which can reduce the peak intensity and smear an acquired image. The principal applications of wavefront control are for improving the image quality in optical imaging systems such as infrared astronomical telescopes, in imaging and tracking rapidly moving space objects, and in compensating for laser beam distortion through the atmosphere. A conventional wavefront correction system consists of a wavefront sensor, a deformable mirror and a control computer. The control computer measures the wavefront distortions using a wavefront sensor and corrects it using a deformable mirror in a closed-loop. Range-gated imaging (RGI) is a direct active visualization technique using a highly sensitive image sensor and a high intensity illuminant. Currently, the range-gated imaging technique providing 2D and 3D images is one of emerging active vision technologies. The range-gated imaging system gets vision information by summing time sliced vision images. In the RGI system, a high intensity illuminant illuminates for ultra-short time and a highly sensitive image sensor is gated by ultra

Image Acquisition of Robust Vision Systems to Monitor Blurred Objects in Hazy Smoking Environments

Energy Technology Data Exchange (ETDEWEB)

Ahn, Yongjin; Park, Seungkyu; Baik, Sunghoon; Kim, Donglyul; Nam, Sungmo; Jeong, Kyungmin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Image information in disaster area or radiation area of nuclear industry is an important data for safety inspection and preparing appropriate damage control plans. So, robust vision system for structures and facilities in blurred smoking environments, such as the places of a fire and detonation, is essential in remote monitoring. Vision systems can't acquire an image when the illumination light is blocked by disturbance materials, such as smoke, fog, dust. The vision system based on wavefront correction can be applied to blurred imaging environments and the range-gated imaging system can be applied to both of blurred imaging and darken light environments. Wavefront control is a widely used technique to improve the performance of optical systems by actively correcting wavefront distortions, such as atmospheric turbulence, thermally-induced distortions, and laser or laser device aberrations, which can reduce the peak intensity and smear an acquired image. The principal applications of wavefront control are for improving the image quality in optical imaging systems such as infrared astronomical telescopes, in imaging and tracking rapidly moving space objects, and in compensating for laser beam distortion through the atmosphere. A conventional wavefront correction system consists of a wavefront sensor, a deformable mirror and a control computer. The control computer measures the wavefront distortions using a wavefront sensor and corrects it using a deformable mirror in a closed-loop. Range-gated imaging (RGI) is a direct active visualization technique using a highly sensitive image sensor and a high intensity illuminant. Currently, the range-gated imaging technique providing 2D and 3D images is one of emerging active vision technologies. The range-gated imaging system gets vision information by summing time sliced vision images. In the RGI system, a high intensity illuminant illuminates for ultra-short time and a highly sensitive image sensor is gated by ultra

Latency and distortion of electromagnetic trackers for augmented reality systems

CERN Document Server

Himberg, Henry

2014-01-01

Augmented reality (AR) systems are often used to superimpose virtual objects or information on a scene to improve situational awareness. Delays in the display system or inaccurate registration of objects destroy the sense of immersion a user experiences when using AR systems. AC electromagnetic trackers are ideal for these applications when combined with head orientation prediction to compensate for display system delays. Unfortunately, these trackers do not perform well in environments that contain conductive or ferrous materials due to magnetic field distortion without expensive calibration

Study of Noise Effects on Rabbit's Hearing Status Using Distortion Product Otoacoustic Emissions

Directory of Open Access Journals (Sweden)

Mojdeh Salehnia

2011-09-01

Full Text Available Background and Aim: Noise-induced hearing loss is the most common problem in industrial areas. This study aimed to determine effects of excessive noise exposure on measurable characteristics of distortion product otoacoustic emissions (DPOAEs in rabbits.Methods: The study was carried out on 12 adult male New Zealand White rabbits including case group - exposed to 500-8000 Hz broadband white noise with 100 dBA SPL for 8 hours per day in 5 consecutive days - and control group. After three days period of acclimatization to the experimental condition, rabbits hearing status in each group were measured by distortion product otoacoustic emissions on days zero means before the study was initiated as a baseline, eight, one hour after the latest exposure to noise, and ten. The recorded results were analyzed using SPSS software.Results: Highest mean distortion product otoacoustic emissions amplitudes in case group were allocated to frequencies of 5888.50 Hz, 8166.50 Hz, 9855.00 Hz, 3956.00 Hz, and 3098.50 Hz, respectively. However, the lowest mean distortion product otoacoustic emissions amplitude was related to frequency of 588.00 Hz (p=0.001.Conclusion: This study revealed that distortion product otoacoustic emissions amplitude shifts due to noise occur first in high and then in middle frequencies. Additionally, exposure to noise can decrease distortion product otoacoustic emissions amplitudes. We conclude that distortion product otoacoustic emissions can be a reliable test for estimating personal susceptibility to noise-induced hearing loss.

Effect of Phase-Encoding Reduction on Geometric Distortion and BOLD Signal Changes in fMRI

Directory of Open Access Journals (Sweden)

Golestan karami

2013-03-01

Full Text Available Introduction Echo-planar imaging (EPI is a group of fast data acquisition methods commonly used in fMRI studies. It acquires multiple image lines in k-space after a single excitation, which leads to a very short scan time. A well-known problem with EPI is that it is more sensitive to distortions due to the used encoding scheme. Source of distortion is inhomogeneity in the static B0 field that causes more geometric distortion in phase encoding direction. This inhomogeneity is induced mainly by the magnetic susceptibility differences between various structures within the object placed inside the scanner, often at air-tissue or bone-tissue interfaces. Methods of reducing EPI distortion are mainly based on decreasing steps of the phase encoding. Reducing steps of phase encoding can be applied by reducing field of view, slice thickness, and/or the use of parallel acquisition technique. Materials and Methods We obtained three data acquisitions with different FOVs including: conventional low resolution, conventional high resolution, and zoomed high resolution EPIs. Moreover we used SENSE technique for phase encoding reduction. All experiments were carried out on three Tesla scanners (Siemens, TIM, and Germany equipped with 12 channel head coil. Ten subjects participated in the experiments. Results The data were processed by FSL software and were evaluated by ANOVA. Distortion was assessed by obtaining low displacement voxels map, and calculated from a field map image. Conclusion We showed that image distortion can be reduced by decreasing slice thickness and phase encoding steps. Distortion reduction in zoomed technique resulted the lowest level, but at the cost of signal-to-noise loss. Moreover, the SENSE technique was shown to decrease the amount of image distortion, efficiently.

A Cognitive Distortions and Deficits Model of Suicide Ideation

Directory of Open Access Journals (Sweden)

Laura L. Fazakas-DeHoog

2017-05-01

Full Text Available Although cognitive distortions and deficits are known risk factors for the development and escalation of suicide ideation and behaviour, no empirical work has examined how these variables interact to predict suicide ideation. The current study proposes an integrative model of cognitive distortions (hopelessness and negative evaluations of self and future and deficits (problem solving deficits, problem solving avoidance, and cognitive rigidity. To test the integrity of this model, a sample of 397 undergraduate students completed measures of deficits, distortions, and current suicide ideation. A structural equation model demonstrated excellent fit, and findings indicated that only distortions have a direct effect on suicidal thinking, whereas cognitive deficits may exert their effects on suicide ideation via their reciprocal relation with distortions. Findings underscore the importance of both cognitive distortions and deficits for understanding suicidality, which may have implications for preventative efforts and treatment.

Impedance Based Analysis of DFIG Stator Current Unbalance and Distortion Suppression Strategies

DEFF Research Database (Denmark)

Song, Yipeng; Zhou, Dao; Blaabjerg, Frede

2016-01-01

The control strategies of Doubly Fed Induction Generator (DFIG) system output current unbalance and distortion suppression have been well investigated in detail, with the implementation of two kinds of resonant regulators, i.e., conventional Resonance (R) regulator or Vector Proportional Integral...... reshaping though the introduction of R and VPI regulator. It is pointed out that, when implemented in the DFIG system output current unbalance and distortion suppression, the VPI regulator (equivalent to the combination of virtual positive inductor and virtual positive resistor) has two advantages over R...... regulator (equivalent to the combination of virtual positive resistor and virtual negative inductor), i.e., better high order harmonic distortion suppression. The theoretical analysis and MATLAB simulation results have validated the correctness of this conclusion....

Bilateral Symmetry of Distortions of Tactile Size Perception.

Science.gov (United States)

Longo, Matthew R; Ghosh, Arko; Yahya, Tasneem

2015-01-01

The perceived distance between touches on the limbs is generally bigger for distances oriented across the width of the limb than for distances oriented along the length of the limb. The present study aimed to investigate the coherence of such distortions of tactile size perception across different skin surfaces. We investigated distortions of tactile size perception on the dorsal and palmar surfaces of both the left and right hands as well as the forehead. Participants judged which of two tactile distances felt larger. One distance was aligned with the proximodistal axis (along the body), the other with the mediolateral axis (across the body). Clear distortions were found on all five skin surfaces, with stimuli oriented across the width of the body being perceived as farther apart than those oriented along the length of the body. Consistent with previous results, distortions were smaller on the palmar than on the dorsal hand surface. Distortion on the forehead was intermediate between the dorsal and palmar surfaces. There were clear correlations between distortion on the left and right hands, for both the dorsal and palmar skin surfaces. In contrast, within each hand, there was no significant correlation between the two skin surfaces. Distortion on the forehead was not significantly correlated with that on any of the other skin surfaces. These results provide evidence for bilaterally symmetric representations underlying tactile size perception. © The Author(s) 2015.

Modeling of radial asymmetry in lens distortion facilitated by modern optimization techniques

CSIR Research Space (South Africa)

De Villiers, Johan P

2010-01-18

Full Text Available when applied to low order models. A new tool has been created which can provide extremely accurate distortion characterization. This allows high-end photogrammetric applications to improve their accuracy even if they already use complex models... distortion with a closed form solution and inverse function, Master’s thesis ], University of Pretoria, Pretoria, RSA (2008). [4] Conrady, A., \\Decentered lens systems," Monthly Notices of the Royal Astronomical Society 79, 384{390 (1919). [5] Brown, D...

Models of brachial to finger pulse wave distortion and pressure decrement.

Science.gov (United States)

Gizdulich, P; Prentza, A; Wesseling, K H

1997-03-01

To model the pulse wave distortion and pressure decrement occurring between brachial and finger arteries. Distortion reversion and decrement correction were also our aims. Brachial artery pressure was recorded intra-arterially and finger pressure was recorded non-invasively by the Finapres technique in 53 adult human subjects. Mean pressure was subtracted from each pressure waveform and Fourier analysis applied to the pulsations. A distortion model was estimated for each subject and averaged over the group. The average inverse model was applied to the full finger pressure waveform. The pressure decrement was modelled by multiple regression on finger systolic and diastolic levels. Waveform distortion could be described by a general, frequency dependent model having a resonance at 7.3 Hz. The general inverse model has an anti-resonance at this frequency. It converts finger to brachial pulsations thereby reducing average waveform distortion from 9.7 (s.d. 3.2) mmHg per sample for the finger pulse to 3.7 (1.7) mmHg for the converted pulse. Systolic and diastolic level differences between finger and brachial arterial pressures changed from -4 (15) and -8 (11) to +8 (14) and +8 (12) mmHg, respectively, after inverse modelling, with pulse pressures correct on average. The pressure decrement model reduced both the mean and the standard deviation of systolic and diastolic level differences to 0 (13) and 0 (8) mmHg. Diastolic differences were thus reduced most. Brachial to finger pulse wave distortion due to wave reflection in arteries is almost identical in all subjects and can be modelled by a single resonance. The pressure decrement due to flow in arteries is greatest for high pulse pressures superimposed on low means.

EP-based wavelet coefficient quantization for linear distortion ECG data compression.

Science.gov (United States)

Hung, King-Chu; Wu, Tsung-Ching; Lee, Hsieh-Wei; Liu, Tung-Kuan

2014-07-01

Reconstruction quality maintenance is of the essence for ECG data compression due to the desire for diagnosis use. Quantization schemes with non-linear distortion characteristics usually result in time-consuming quality control that blocks real-time application. In this paper, a new wavelet coefficient quantization scheme based on an evolution program (EP) is proposed for wavelet-based ECG data compression. The EP search can create a stationary relationship among the quantization scales of multi-resolution levels. The stationary property implies that multi-level quantization scales can be controlled with a single variable. This hypothesis can lead to a simple design of linear distortion control with 3-D curve fitting technology. In addition, a competitive strategy is applied for alleviating data dependency effect. By using the ECG signals saved in MIT and PTB databases, many experiments were undertaken for the evaluation of compression performance, quality control efficiency, data dependency influence. The experimental results show that the new EP-based quantization scheme can obtain high compression performance and keep linear distortion behavior efficiency. This characteristic guarantees fast quality control even for the prediction model mismatching practical distortion curve. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

Systems and methods for mirror mounting with minimized distortion

Science.gov (United States)

Antonille, Scott R. (Inventor); Wallace, Thomas E. (Inventor); Content, David A. (Inventor); Wake, Shane W. (Inventor)

2012-01-01

A method for mounting a mirror for use in a telescope includes attaching the mirror to a plurality of adjustable mounts; determining a distortion in the mirror caused by the plurality adjustable mounts, and, if the distortion is determined to be above a predetermined level: adjusting one or more of the adjustable mounts; and determining the distortion in the mirror caused by the adjustable mounts; and in the event the determined distortion is determined to be at or below the predetermined level, rigidizing the adjustable mounts.

Studies of field distortions in a time projection chamber for the International Linear Collider

International Nuclear Information System (INIS)

Zenker, Klaus

2014-12-01

The International Linear Collider (ILC) will allow to do precision measurements of Standard Model parameter and to search for new physics. The ILD detector concept, which is developed for the ILC, uses a Time Projection Chamber (TPC) as central tracking device. The momentum resolution goal for the ILD TPC is δ(1/p t ) ≅ 10 -4 (GeV/c) -1 at a magnetic field of B=3.5 T. Field distortions of the magnetic or electric field inside the sensitive volume of the TPC distort the momentum measurements. Therefore, one needs to keep them under control and correct them with high precision. In this thesis the main sources of field distortions in the TPC are identified and their effects are determined. Furthermore, possibilities to reduce the identified field distortions are presented. One known source of distortions of the electric field are ions, produced by the gas amplification in the TPC anode, that drift into the sensitive volume of the TPC. In the first part of this work the creation of these ions in Gas Electron Multiplier (GEM), which are used for the gas amplification, is studied. It will be shown that the resulting field distortions are not acceptable at the ILD TPC. By tuning the parameters of the gas amplification at the anode the field distortion can be reduced, which is shown in measurements and simulations. In addition measurements using a modified GEM show that it is possible to further reduce the field distortions with such a GEM. In the second part of this work field distortions arising at boundaries between individual readout modules are investigated using simulation studies. It will be shown in simulations, which are verified by measurement results, that these field distortions significantly influence the readout module performance. Based on the simulation results the GEM based readout module developed at DESY is optimised and the field distortions are reduced. These performance improvements could also be verified in measurements. Finally, a laser

Modelling the Perceptual Components of Loudspeaker Distortion

DEFF Research Database (Denmark)

Olsen, Sune L.; Agerkvist, Finn T.; MacDonald, Ewen

2016-01-01

While non-linear distortion in loudspeakers decreases audio quality, the perceptual consequences can vary substantially. This paper investigates the metric Rnonlin [1] which was developed to predict subjective measurements of sound quality in nonlinear systems. The generalisability of the metric...... the perceptual consequences of non-linear distortion....

Modeling Kinetics of Distortion in Porous Bi-layered Structures

DEFF Research Database (Denmark)

Tadesse Molla, Tesfaye; Frandsen, Henrik Lund; Bjørk, Rasmus

2013-01-01

because of different sintering rates of the materials resulting in undesired distortions of the component. An analytical model based on the continuum theory of sintering has been developed to describe the kinetics of densification and distortion in the sintering processes. A new approach is used...... to extract the material parameters controlling shape distortion through optimizing the model to experimental data of free shrinkage strains. The significant influence of weight of the sample (gravity) on the kinetics of distortion is taken in to consideration. The modeling predictions indicate good agreement...

CMB spectral distortions as solutions to the Boltzmann equations

Energy Technology Data Exchange (ETDEWEB)

Ota, Atsuhisa, E-mail: a.ota@th.phys.titech.ac.jp [Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan)

2017-01-01

We propose to re-interpret the cosmic microwave background spectral distortions as solutions to the Boltzmann equation. This approach makes it possible to solve the second order Boltzmann equation explicitly, with the spectral y distortion and the momentum independent second order temperature perturbation, while generation of μ distortion cannot be explained even at second order in this framework. We also extend our method to higher order Boltzmann equations systematically and find new type spectral distortions, assuming that the collision term is linear in the photon distribution functions, namely, in the Thomson scattering limit. As an example, we concretely construct solutions to the cubic order Boltzmann equation and show that the equations are closed with additional three parameters composed of a cubic order temperature perturbation and two cubic order spectral distortions. The linear Sunyaev-Zel'dovich effect whose momentum dependence is different from the usual y distortion is also discussed in the presence of the next leading order Kompaneets terms, and we show that higher order spectral distortions are also generated as a result of the diffusion process in a framework of higher order Boltzmann equations. The method may be applicable to a wider class of problems and has potential to give a general prescription to non-equilibrium physics.

Distortional solutions for loaded semi-discretized thin-walled beams

DEFF Research Database (Denmark)

Andreassen, Michael Joachim; Jönsson, Jeppe

2012-01-01

distortional displacement fields which decouple the reduced order differential equations. In this process the cross section is discretized into finite cross-section elements, and the natural distortional modes as well as the related axial variations are found as solutions to the established coupled fourth...... order homogeneous differential equations of GBT.In this paper the non-homogeneous distortional differential equations of GBT are formulated using this novel semi-discretization process. Transforming these non-homogeneous distortional differential equations into the natural eigenmode space by using...... the distortional modal matrix found for the homogeneous system, we get the uncoupled set of differential equations including the distributed loads. This uncoupling is very important in GBT, since the shear stiffness contribution from St. Venant torsional shear stress as well as “Bredt's shear flow” cannot...

Deep subcritical levels measurements dependents upon kinetic distortion factors

International Nuclear Information System (INIS)

Pan Shibiao; Li Xiang; Fu Guo'en; Huang Liyuan; Mu Keliang

2013-01-01

The measurement of deep subcritical levels, with the increase of subcriticality, showed that the results impact on the kinetic distortion effect, along with neutron flux strongly deteriorated. Using the diffusion theory, calculations have been carried out to quantify the kinetic distortion correction factors in subcritical systems, and these indicate that epithermal neutron distributions are strongly affected by kinetic distortion. Subcriticality measurements in four different rod-state combination at the zero power device was carried out. The test data analysis shows that, with increasing subcriticality, kinetic distortion effect correction factor gradually increases from 1.052 to 1.065, corresponding reactive correction amount of 0.78β eff ∼ 3.01β eff . Thus, it is necessary to consider the kinetic distortion effect in the deep subcritical reactivity measurements. (authors)

Lattice shear distortions in fluorite structure oxides

International Nuclear Information System (INIS)

Faber, J. Jr.; Mueller, M.H.; Hitterman, R.L.

1979-01-01

Crystallographic shear distortions have been observed in fluorite structure, single crystals of UO 2 and Zr(Ca)O 2 /sub-x/ by neutron-diffraction techniques. These distortions localize on the oxygen sublattice and do not require the presence of an external strain. The internal rearrangement mode in UO 2 is a transverse, zone boundary q vector = 2π/a (0.5, 0.0) deformation with amplitude 0.014 A. In Zr(Ca)O/sub 2-x/, the mode is a longitudinal, q vector = 2-/a (0,0,0.5) deformation with amplitude 0.23 A. Cation-anion elastic interactions dominate in selecting the nature of the internal distortion

Welding distortion control in double walled KSTAR vacuum vessel fabrication

International Nuclear Information System (INIS)

Oh, D. W.; Lee, G. T.; Kim, H. K.; Yang, H. L.; Bak, J. S.

2004-01-01

The KSTAR(Korea Superconducting Tokamak Advanced Research) vacuum vessel is designed to be a double walled structure made of 12mm thick 316LN stainless steel with a D shaped cross-section about 4 m height. Vacuum vessel was pre-fabricated in two parts, 180 degree and 157.5 degree sectors in toroidal direction to meet the transportation purpose. These two parts have to be welded on site with ±2mm allowable fabrication tolerances. 1/3 scaled mock-up model was used to estimate the welding distortion and to ensure the weld quality of vacuum vessel. Gas Tungsten Arc Welding(GTAW), which has been approved by procedure qualification test, was used during mock-up test and vacuum vessel site fabrication. Welding distortion could be managed by allowing for distortion in opposite direction, by applying high restraint using lots of strong backs, by controlling the welding heat input with symmetrical welding sequence. The integrity of the site welding joint was assured by radiographic test, ultrasonic test and leak test with helium detecting method

Effects of image distortion correction on voxel-based morphometry

International Nuclear Information System (INIS)

Goto, Masami; Abe, Osamu; Kabasawa, Hiroyuki

2012-01-01

We aimed to show that correcting image distortion significantly affects brain volumetry using voxel-based morphometry (VBM) and to assess whether the processing of distortion correction reduces system dependency. We obtained contiguous sagittal T 1 -weighted images of the brain from 22 healthy participants using 1.5- and 3-tesla magnetic resonance (MR) scanners, preprocessed images using Statistical Parametric Mapping 5, and tested the relation between distortion correction and brain volume using VBM. Local brain volume significantly increased or decreased on corrected images compared with uncorrected images. In addition, the method used to correct image distortion for gradient nonlinearity produced fewer volumetric errors from MR system variation. This is the first VBM study to show more precise volumetry using VBM with corrected images. These results indicate that multi-scanner or multi-site imaging trials require correction for distortion induced by gradient nonlinearity. (author)

The evolution of costly mate choice against segregation distorters.

Science.gov (United States)

Manser, Andri; Lindholm, Anna K; Weissing, Franz J

2017-12-01

The evolution of female preference for male genetic quality remains a controversial topic in sexual selection research. One well-known problem, known as the lek paradox, lies in understanding how variation in genetic quality is maintained in spite of natural selection and sexual selection against low-quality alleles. Here, we theoretically investigate a scenario where females pay a direct fitness cost to avoid males carrying an autosomal segregation distorter. We show that preference evolution is greatly facilitated under such circumstances. Because the distorter is transmitted in a non-Mendelian fashion, it can be maintained in the population despite directional sexual selection. The preference helps females avoid fitness costs associated with the distorter. Interestingly, we find that preference evolution is limited if the choice allele induces a very strong preference or if distortion is very strong. Moreover, the preference can only persist in the presence of a signal that reliably indicates a male's distorter genotype. Hence, even in a system where the lek paradox does not play a major role, costly preferences can only spread under specific circumstances. We discuss the importance of distorter systems for the evolution of costly female choice and potential implications for the use of artificial distorters in pest control. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Spatial distortion in MRI with application to stereotactic neurosurgery

International Nuclear Information System (INIS)

Morgan, P.S.

1999-05-01

The aim of this work was to implement a thorough method for quantifying the errors introduced to frame-based neurosurgical stereotactic procedures by the use of MRI. Chang and Fitzpatrick's reversed gradient distortion correction method was used, in combination with a phantom, to measure these errors. Spatial distortion in MR images of between 1 mm and 2 mm was measured. Further analysis showed that this typically introduced an additional error in the coordinate of the actual treatment point of 0.7 mm. The implications of this are discussed. The main source of distortion in the MR images used for stereotaxis was found to be the head ring. A comparison between imaging sequences and MR scanners revealed that the spatial distortion depends mainly on the bandwidth per pixel of the sequence rather than other differences in the imaging sequences. By comparison with a phase map distortion correction technique, the imaging parameters required to allow successful distortion correction with the reversed gradient method were identified. The most important was the use of full Fourier spin echo acquisitions. The reversed gradient correction method was applied to two contemporary EPI techniques. Considerable improvement was seen in the production of ADC maps after the images had been corrected for distortion. The method also was shown to be valid in application to BOLD fMRl data. (author)

The influence of item order on intentional response distortion in the assessment of high potentials: assessing pilot applicants.

Science.gov (United States)

Khorramdel, Lale; Kubinger, Klaus D; Uitz, Alexander

2014-04-01

An experiment was conducted to investigate the effects of item order and questionnaire content on faking good or intentional response distortion. It was hypothesized that intentional response distortion would either increase towards the end of a long questionnaire, as learning effects might make it easier to adjust responses to a faking good schema, or decrease because applicants' will to distort responses is reduced if the questionnaire lasts long enough. Furthermore, it was hypothesized that certain types of questionnaire content are especially vulnerable to response distortion. Eighty-four pre-selected pilot applicants filled out a questionnaire consisting of 516 items including items from the NEO five factor inventory (NEO FFI), NEO personality inventory revised (NEO PI-R) and business-focused inventory of personality (BIP). The positions of the items were varied within the applicant sample to test if responses are affected by item order, and applicants' response behaviour was additionally compared to that of volunteers. Applicants reported significantly higher mean scores than volunteers, and results provide some evidence of decreased faking tendencies towards the end of the questionnaire. Furthermore, it could be demonstrated that lower variances or standard deviations in combination with appropriate (often higher) mean scores can serve as an indicator for faking tendencies in group comparisons, even if effects are not significant. © 2013 International Union of Psychological Science.

Distortion dependent intersystem crossing

DEFF Research Database (Denmark)

Stephansen, Anne Boutrup; Sølling, Theis Ivan

2017-01-01

. The effect is observed to increase in the presence of methyl-groups on the pinnacle carbon-atoms, where largest extents of r and p orbital-mixing are observed. This is fully consistent with the time-resolved spectroscopy data: Toluene and p-xylene show evidence for ultrafast triplet formation competing......The competition between ultrafast intersystem crossing and internal conversion in benzene, toluene, and p-xylene is investigated with time-resolved photoelectron spectroscopy and quantum chemical calculations. By exciting to S2 out-of-plane symmetry breaking, distortions are activated at early...... times whereupon spin-forbidden intersystem crossing becomes (partly) allowed. Natural bond orbital analysis suggests that the pinnacle carbon atoms distorting from the aromatic plane change hybridization between the planar Franck-Condon geometry and the deformed (boat-shaped) S2 equilibrium geometry...

Distortion correction algorithm for UAV remote sensing image based on CUDA

International Nuclear Information System (INIS)

Wenhao, Zhang; Yingcheng, Li; Delong, Li; Changsheng, Teng; Jin, Liu

2014-01-01

In China, natural disasters are characterized by wide distribution, severe destruction and high impact range, and they cause significant property damage and casualties every year. Following a disaster, timely and accurate acquisition of geospatial information can provide an important basis for disaster assessment, emergency relief, and reconstruction. In recent years, Unmanned Aerial Vehicle (UAV) remote sensing systems have played an important role in major natural disasters, with UAVs becoming an important technique of obtaining disaster information. UAV is equipped with a non-metric digital camera with lens distortion, resulting in larger geometric deformation for acquired images, and affecting the accuracy of subsequent processing. The slow speed of the traditional CPU-based distortion correction algorithm cannot meet the requirements of disaster emergencies. Therefore, we propose a Compute Unified Device Architecture (CUDA)-based image distortion correction algorithm for UAV remote sensing, which takes advantage of the powerful parallel processing capability of the GPU, greatly improving the efficiency of distortion correction. Our experiments show that, compared with traditional CPU algorithms and regardless of image loading and saving times, the maximum acceleration ratio using our proposed algorithm reaches 58 times that using the traditional algorithm. Thus, data processing time can be reduced by one to two hours, thereby considerably improving disaster emergency response capability

Balanced steady-state free precession with parallel imaging gives distortion-free fMRI with high temporal resolution.

Science.gov (United States)

Chappell, Michael; Håberg, Asta K; Kristoffersen, Anders

2011-01-01

Research on the functions of the human brain requires that functional magnetic resonance imaging (MRI) moves towards producing images with less distortion and higher temporal and spatial resolution. This study compares passband balanced steady-state free precession (bSSFP) acquisitions with and without parallel imaging (PI) to investigate whether combining PI with this pulse sequence is a viable option for functional MRI. Such a novel combination has the potential to offer the distortion-free advantages of bSSFP with the reduced acquisition time of PI. Scans were done on a Philips 3T Intera, using the installed bSSFP pulse sequence, both with and without the sensitivity encoding (SENSE) PI option. The task was a visual flashing checkerboard, and the viewing window covered the visual cortex. Sensitivity comparisons with and without PI were done using the same manually drawn region of interest for each time course of the subject, and comparing the z-score summary statistics: number of voxels with z>2.3, the mean of those voxels, their 90th percentile and their maximum value. We show that PI greatly improves the temporal resolution in bSSFP, reducing the volume acquisition time by more than half in this study to 0.67 s with 3-mm isotropic voxels. At the same time, a statistically significant increase was found for the maximum z-score using bSSFP with PI as compared to without it (P=.02). This improvement can be understood in terms of physiological noise, as demonstrated by noise measurements. This produces observed increases in the overall temporal signal to noise of the functional time series, giving greater sensitivity to functional activations with PI. This study demonstrates for the first time the possibility of combining PI with bSSFP to achieve distortion-free functional images without loss of sensitivity and with high temporal resolution. Copyright © 2011 Elsevier Inc. All rights reserved.

No Correlation between Distorted Body Representations Underlying Tactile Distance Perception and Position Sense

Directory of Open Access Journals (Sweden)

Matthew R. Longo

2016-11-01

Full Text Available Both tactile distance perception and position sense are believed to require that immediate afferent signals be referenced to a stored representation of body size and shape (the body model. For both of these abilities, recent studies have reported that the stored body representations involved are highly distorted, at least in the case of the hand, with the hand dorsum represented as wider and squatter than it actually is. Here, we investigated whether individual differences in the magnitude of these distortions are shared between tactile distance perception and position sense, as would be predicted by the hypothesis that a single distorted body model underlies both tasks. We used established task to measure distortions of the represented shape of the hand dorsum. Consistent with previous results, in both cases there were clear biases to overestimate distances oriented along the medio-lateral axis of the hand compared to the proximo-distal axis. Moreover, within each task there were clear split-half correlations, demonstrating that both tasks show consistent individual differences. Critically, however, there was no correlation between the magnitudes of distortion in the two tasks. This casts doubt on the proposal that a common body model underlies both tactile distance perception and position sense.

Synchronization of grid-connected renewable energy sources under highly distorted voltages and unbalanced grid faults

DEFF Research Database (Denmark)

Hadjidemetriou, Lenos; Kyriakides, Elias; Blaabjerg, Frede

2013-01-01

Renewable energy sources require accurate and appropriate performance not only under normal grid operation but also under abnormal and faulty grid conditions according to the modern grid codes. This paper proposes a novel phase-locked loop algorithm (MSHDC-PLL), which can enable the fast...... and dynamic synchronization of the interconnected renewable energy system under unbalanced grid faults and under highly harmonic distorted voltage. The outstanding performance of the suggested PLL is achieved by implementing an innovative multi-sequence/harmonic decoupling cell in order to dynamically cancel...... renewable energy systems. Therefore, the performance of the new PLL can increase the quality of the injected power under abnormal conditions and in addition enable the renewable energy systems to provide the appropriate support to the grid under balanced and unbalanced grid faults....

Molecular dynamics study on microstructure of near grain boundary distortion region in small grain size nano- NiAl alloy

International Nuclear Information System (INIS)

Wang, J.Y.; Wang, X.W.; Rifkin, J.; Li, D.X.

2001-12-01

Using the molecular dynamics simulation method, the microstructure of distortion region near curved amorphous-like grain boundary in nano-NiAl alloy is studied. The results showed that due to the internal elastic force of high energy grain boundary, distortion layer exists between grain and grain boundary. The lattice expansion and structure factor decreasing are observed in this region. Stacking fault in sample with grain size 3.8nm is clearly observed across the distortion region at the site very close to grain. The influences of different grain sizes on average distortion degree and volume fractions of distortion region, grain and grain boundary are also discussed. (author)

Word Recognition for Temporally and Spectrally Distorted Materials

DEFF Research Database (Denmark)

Smith, Sherri L.; Pichora-Fuller, Margaret Kathleen; Wilson, Richard H.

2012-01-01

listeners with near-normal hearing and hearing loss performed best in the unaltered condition, followed by the jitter and smear conditions, with the poorest performance in the combined jitter-smear condition in both quiet and noise. Overall, listeners with near-normal hearing performed better than listeners...... to predict group differences, but not the effects of distortion. Individual differences in performance were similar across all distortion conditions with both age and hearing loss being implicated. The speech materials needed to be both spectrally and temporally distorted to mimic the effects of age...

Rate-distortion theory and human perception.

Science.gov (United States)

Sims, Chris R

2016-07-01

The fundamental goal of perception is to aid in the achievement of behavioral objectives. This requires extracting and communicating useful information from noisy and uncertain sensory signals. At the same time, given the complexity of sensory information and the limitations of biological information processing, it is necessary that some information must be lost or discarded in the act of perception. Under these circumstances, what constitutes an 'optimal' perceptual system? This paper describes the mathematical framework of rate-distortion theory as the optimal solution to the problem of minimizing the costs of perceptual error subject to strong constraints on the ability to communicate or transmit information. Rate-distortion theory offers a general and principled theoretical framework for developing computational-level models of human perception (Marr, 1982). Models developed in this framework are capable of producing quantitatively precise explanations for human perceptual performance, while yielding new insights regarding the nature and goals of perception. This paper demonstrates the application of rate-distortion theory to two benchmark domains where capacity limits are especially salient in human perception: discrete categorization of stimuli (also known as absolute identification) and visual working memory. A software package written for the R statistical programming language is described that aids in the development of models based on rate-distortion theory. Copyright © 2016 The Author. Published by Elsevier B.V. All rights reserved.

Color correction for chromatic distortion in a multi-wavelength digital holographic system

International Nuclear Information System (INIS)

Lin, Li-Chien; Huang, Yi-Lun; Tu, Han-Yen; Lai, Xin-Ji; Cheng, Chau-Jern

2011-01-01

A multi-wavelength digital holographic (MWDH) system has been developed to record and reconstruct color images. In comparison to working with digital cameras, however, high-quality color reproduction is difficult to achieve, because of the imperfections from the light sources, optical components, optical recording devices and recording processes. Thus, we face the problem of correcting the colors altered during the digital holographic process. We therefore propose a color correction scheme to correct the chromatic distortion caused by the MWDH system. The scheme consists of two steps: (1) creating a color correction profile and (2) applying it to the correction of the distorted colors. To create the color correction profile, we generate two algorithms: the sequential algorithm and the integrated algorithm. The ColorChecker is used to generate the distorted colors and their desired corrected colors. The relationship between these two color patches is fixed into a specific mathematical model, the parameters of which are estimated, creating the profile. Next, the profile is used to correct the color distortion of images, capturing and preserving the original vibrancy of the reproduced colors for different reconstructed images

An Iterative Optimization Algorithm for Lens Distortion Correction Using Two-Parameter Models

Directory of Open Access Journals (Sweden)

Daniel Santana-Cedrés

2016-12-01

Full Text Available We present a method for the automatic estimation of two-parameter radial distortion models, considering polynomial as well as division models. The method first detects the longest distorted lines within the image by applying the Hough transform enriched with a radial distortion parameter. From these lines, the first distortion parameter is estimated, then we initialize the second distortion parameter to zero and the two-parameter model is embedded into an iterative nonlinear optimization process to improve the estimation. This optimization aims at reducing the distance from the edge points to the lines, adjusting two distortion parameters as well as the coordinates of the center of distortion. Furthermore, this allows detecting more points belonging to the distorted lines, so that the Hough transform is iteratively repeated to extract a better set of lines until no improvement is achieved. We present some experiments on real images with significant distortion to show the ability of the proposed approach to automatically correct this type of distortion as well as a comparison between the polynomial and division models.

The role of visual similarity and memory in body model distortions.

Science.gov (United States)

Saulton, Aurelie; Longo, Matthew R; Wong, Hong Yu; Bülthoff, Heinrich H; de la Rosa, Stephan

2016-02-01

Several studies have shown that the perception of one's own hand size is distorted in proprioceptive localization tasks. It has been suggested that those distortions mirror somatosensory anisotropies. Recent research suggests that non-corporeal items also show some spatial distortions. In order to investigate the psychological processes underlying the localization task, we investigated the influences of visual similarity and memory on distortions observed on corporeal and non-corporeal items. In experiment 1, participants indicated the location of landmarks on: their own hand, a rubber hand (rated as most similar to the real hand), and a rake (rated as least similar to the real hand). Results show no significant differences between rake and rubber hand distortions but both items were significantly less distorted than the hand. Experiments 2 and 3 explored the role of memory in spatial distance judgments of the hand, the rake and the rubber hand. Spatial representations of items measured in experiments 2 and 3 were also distorted but showed the tendency to be smaller than in localization tasks. While memory and visual similarity seem to contribute to explain qualitative similarities in distortions between the hand and non-corporeal items, those factors cannot explain the larger magnitude observed in hand distortions. Copyright © 2015. Published by Elsevier B.V.

Distorted wave calculations for double electron transfer

International Nuclear Information System (INIS)

Martinez, A.E.; Rivarola, R.D.; Gayet, R.; Hanssen, J.

1992-01-01

The resonant double electron capture by alpha particles in helium targets is studied, at intermediate and high collision energies, using the Continuum Distorted Wave - Eikonal Initial State (CDW-EIS) model. Differential and total cross sections for capture into the He (1 s 2 ) final state are calculated in the framework of an Independent Electron Approximation (IEA). Theoretical results are compared with the experimental data available at present for capture into any final state of helium. (author)

Fisheye image rectification using spherical and digital distortion models

Science.gov (United States)

Li, Xin; Pi, Yingdong; Jia, Yanling; Yang, Yuhui; Chen, Zhiyong; Hou, Wenguang

2018-02-01

Fisheye cameras have been widely used in many applications including close range visual navigation and observation and cyber city reconstruction because its field of view is much larger than that of a common pinhole camera. This means that a fisheye camera can capture more information than a pinhole camera in the same scenario. However, the fisheye image contains serious distortion, which may cause trouble for human observers in recognizing the objects within. Therefore, in most practical applications, the fisheye image should be rectified to a pinhole perspective projection image to conform to human cognitive habits. The traditional mathematical model-based methods cannot effectively remove the distortion, but the digital distortion model can reduce the image resolution to some extent. Considering these defects, this paper proposes a new method that combines the physical spherical model and the digital distortion model. The distortion of fisheye images can be effectively removed according to the proposed approach. Many experiments validate its feasibility and effectiveness.

Mesoscopic Elastic Distortions in GaAs Quantum Dot Heterostructures.

Science.gov (United States)

Pateras, Anastasios; Park, Joonkyu; Ahn, Youngjun; Tilka, Jack A; Holt, Martin V; Reichl, Christian; Wegscheider, Werner; Baart, Timothy A; Dehollain, Juan Pablo; Mukhopadhyay, Uditendu; Vandersypen, Lieven M K; Evans, Paul G

2018-05-09

Quantum devices formed in high-electron-mobility semiconductor heterostructures provide a route through which quantum mechanical effects can be exploited on length scales accessible to lithography and integrated electronics. The electrostatic definition of quantum dots in semiconductor heterostructure devices intrinsically involves the lithographic fabrication of intricate patterns of metallic electrodes. The formation of metal/semiconductor interfaces, growth processes associated with polycrystalline metallic layers, and differential thermal expansion produce elastic distortion in the active areas of quantum devices. Understanding and controlling these distortions present a significant challenge in quantum device development. We report synchrotron X-ray nanodiffraction measurements combined with dynamical X-ray diffraction modeling that reveal lattice tilts with a depth-averaged value up to 0.04° and strain on the order of 10 -4 in the two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure. Elastic distortions in GaAs/AlGaAs heterostructures modify the potential energy landscape in the 2DEG due to the generation of a deformation potential and an electric field through the piezoelectric effect. The stress induced by metal electrodes directly impacts the ability to control the positions of the potential minima where quantum dots form and the coupling between neighboring quantum dots.

Distortions in the output signals of conventional spectrum analyzers

International Nuclear Information System (INIS)

Njau, E.C.

1988-08-01

We show that the output signals of conventional spectrum analysers contain distortions which basically originate from the signal processing performed inside the analysers' frequency convertors. Total elimination of these distortions through normal filtering techniques is difficult owing to the closeness of some of their frequencies to the corresponding frequencies of the required signals. Simple design adjustments that can minimize these distortions are suggested. (author). 7 refs, 2 figs

Clinicopathogical characteristics and mammographic features of breast cancer showing architectural distortion on a mammogram

International Nuclear Information System (INIS)

Kanzaki, Masao; Hirose, Naoko; Suwa, Kaori; Yoshida, Masayuki; Otuki, Yoshiro; Kobayashi, Hiroshi

2012-01-01

Seven hundred and twenty-seven cases of breast cancer were diagnosed in this clinic between January 2003 and December 2010. Of those, 97 patients who showed architectural distortion on mammography were examined regarding the clinicopathological characteristics and mammographic features. The overall rate of architectural distortion was 13.3%, which became higher with progression of the clinical stage. The rate of lymph node metastasis was 50.5% histologically, and the most common histological type was scirrhous carcinoma at 36.2%, papillotubular carcinoma at 33%, invasive lobular carcinoma at 12.1%, and ductal carcinoma in situ at 11%. Cases of extensive ductal spread beyond the breast quadrant, accompanied by microcalcifications or showing architectural distortion in two views on mammography, were present at significantly high rates. Cases showing architectural distortion in two views on mammography accounted for 66% of the total, and, when these cases were not associated with any other mammographic findings, the most suspected histology of the lesion was invasive lobular carcinoma or carcinoma in situ. (author)

Appraisal Distortions and Intimate Partner Violence: Gender, Power, and Interaction

Science.gov (United States)

Whiting, Jason B.; Oka, Megan; Fife, Stephen T.

2012-01-01

In relationships characterized by control, abuse, or violence, many appraisal distortions occur including denial and minimization. However, the nature of the distortion varies depending on the individual's role in the relationship (i.e., abuser or victim). Reducing these distortions is an important component in treatment success and involves…

Behavior of TPC`s in a high particle flux environment

Energy Technology Data Exchange (ETDEWEB)

Etkin, A.; Eiseman, S.E.; Foley, K.J.; Hackenburg, R.W.; Longacre, R.S.; Love, W.A.; Morris, T.W.; Platner, E.D.; Saulys, A.C.; Lindenbaum, S.J. [Brookhaven National Lab., Upton, NY (United States); Chan, C.S.; Kramer, M.A.; Zhao, K.H.; Zhu, Y. [City College of New York, New York (United States); Hallman, T.J.; Madansky, L. [Johns Hopkins Univ., Baltimore, MD (United States); Ahmad, S.; Bonner, B.E.; Buchanan, J.A.; Chiou, C.N.; Clement, J.M.; Mutchler, G.S.; Roberts, J.B. [Bonner Nuclear Lab., Houston, TX (United States)

1991-12-31

TPC`s (Time Projection Chamber) used in E-810 at the TAGS (Alternating Gradient Synchrotron) were exposed to fluxes equivalent to more than 10 minimum ionizing particles per second to find if such high fluxes cause gain changes or distortions of the electric field. Initial results of these and other tests are presented and the consequences for the RHIC (Relativistic Heavy Ion Collider) TPC-based experiments are discussed.

Comparison of Engine/Inlet Distortion Measurements with MEMS and ESP Pressure Sensors

Science.gov (United States)

Soto, Hector L.; Hernandez, Corey D.

2004-01-01

A study of active-flow control in a small-scale boundary layer ingestion inlet was conducted at the NASA Langley Basic Aerodynamic Research Tunnel (BART). Forty MEMS pressure sensors, in a rake style configuration, were used to examine both the mean (DC) and high frequency (AC) components of the total pressure across the inlet/engine interface plane. The mean component was acquired and used to calculate pressure distortion. The AC component was acquired separately, at a high sampling rate, and is used to study the unsteady effects of the active-flow control. An identical total pressure rake, utilizing an Electronically Scanned Pressure (ESP) system, was also used to calculate distortion; a comparison of the results obtained using the two rakes is presented.

Testing inflation and curvaton scenarios with CMB distortions

International Nuclear Information System (INIS)

Clesse, Sébastien; Garbrecht, Björn; Zhu, Yi

2014-01-01

Prior to recombination, Silk damping causes the dissipation of energy from acoustic waves into the monopole of the Cosmic Microwave Background (CMB), resulting in spectral distortions. These can be used to probe the primordial scalar power spectrum on smaller scales than it is possible with CMB anisotropies. An enhancement of power on these scales is nevertheless required for the resulting distortions to be detectable by future experiments like PIXIE. In this paper, we examine all 49 single-field inflation models listed by Martin et al. in the Encyclopaedia Inflationaris [1] and find that only one of these may lead to a detectable level of distortions in a tuned region of its parameter space, namely the original hybrid model. Three effective multi-field scenarios are also studied: with softly and suddenly turning trajectories, and with a mild waterfall trajectory. Softly turning trajectories do not induce distortions at any detectable level, whereas a sudden turn in the field space or a mild waterfall trajectory predicts a peak (plus damped oscillations in the sudden turn case) in the scalar power spectrum, which can lead to an observable amount of CMB distortions. Finally, another scenario leading to potentially detectable distortions involves a curvaton whose blue spectrum is subdominant on CMB angular scales and overtakes the inflaton spectrum on smaller scales. In this case however, we show that the bounds from ultra compact minihaloes are not satisfied. Expectations for an ultimate PRISM-class experiment characterized by an improvement in sensitivity by a factor of ten are discussed for some models

Testing inflation and curvaton scenarios with CMB distortions

Science.gov (United States)

Clesse, Sébastien; Garbrecht, Björn; Zhu, Yi

2014-10-01

Prior to recombination, Silk damping causes the dissipation of energy from acoustic waves into the monopole of the Cosmic Microwave Background (CMB), resulting in spectral distortions. These can be used to probe the primordial scalar power spectrum on smaller scales than it is possible with CMB anisotropies. An enhancement of power on these scales is nevertheless required for the resulting distortions to be detectable by future experiments like PIXIE. In this paper, we examine all 49 single-field inflation models listed by Martin et al. in the Encyclopaedia Inflationaris [1] and find that only one of these may lead to a detectable level of distortions in a tuned region of its parameter space, namely the original hybrid model. Three effective multi-field scenarios are also studied: with softly and suddenly turning trajectories, and with a mild waterfall trajectory. Softly turning trajectories do not induce distortions at any detectable level, whereas a sudden turn in the field space or a mild waterfall trajectory predicts a peak (plus damped oscillations in the sudden turn case) in the scalar power spectrum, which can lead to an observable amount of CMB distortions. Finally, another scenario leading to potentially detectable distortions involves a curvaton whose blue spectrum is subdominant on CMB angular scales and overtakes the inflaton spectrum on smaller scales. In this case however, we show that the bounds from ultra compact minihaloes are not satisfied. Expectations for an ultimate PRISM-class experiment characterized by an improvement in sensitivity by a factor of ten are discussed for some models.

Are there common mechanisms in sensation seeking and reality distortion in schizophrenia? A study using memory event-related potentials.

Science.gov (United States)

Guillem, François; Pampoulova, Tania; Stip, Emmanuel; Todorov, Christo; Lalonde, Pierre

2005-05-15

A growing literature suggests that the characteristics of sensation seeking and reality distortion expressed in schizophrenia share several mechanisms. In a previous study, the comparison of patients with high vs. low reality distortion using event-related potentials (ERPs) recorded in a recognition memory task for unfamiliar faces identified neural and cognitive anomalies specifically related to the expression of these symptoms. As a follow-up, this study investigated the ERP correlates of sensation seeking in schizophrenia using the same recognition memory protocol. ERPs have been recorded in controls (N=21) and schizophrenia patients separated into high (HSS; N=13) and low (LSS; N=17) scorers according to Zuckerman's Sensation Seeking Scale. The results show a reduced P2a that was found unrelated to reality distortion in the previous study of reality distortion. It identifies interference inhibition impairment as being specifically related to sensation seeking. On the other hand, HSS scorers display enhanced fronto-central and normal P600 effects also found in high reality distortion patients. These results indicate inappropriate context processing and mnemonic binding common to sensation seeking and reality distortion. LSS scorers also display a reduced temporal N300 similar to that found in low reality distortion patients. This anomaly could reflect the lower reactivity to emotionally significant stimuli that underlies anhedonia symptoms. Finally, the N400 effect and a late frontal effect are found in both HSS and LSS. Since they were unrelated to reality distortion, these indices have been related to basic aspects of schizophrenia, e.g., deficient knowledge integration, or other mechanisms, e.g. anxiety or impulsivity. In summary, the present study examines the strategy of investigating variables, such as temperamental characteristics, in addition to symptoms, to show how discrete impairments may contribute to the expression of the illness.

Distortion-Based Link Adaptation for Wireless Video Transmission

Directory of Open Access Journals (Sweden)

Andrew Nix

2008-06-01

Full Text Available Wireless local area networks (WLANs such as IEEE 802.11a/g utilise numerous transmission modes, each providing different throughputs and reliability levels. Most link adaptation algorithms proposed in the literature (i maximise the error-free data throughput, (ii do not take into account the content of the data stream, and (iii rely strongly on the use of ARQ. Low-latency applications, such as real-time video transmission, do not permit large numbers of retransmission. In this paper, a novel link adaptation scheme is presented that improves the quality of service (QoS for video transmission. Rather than maximising the error-free throughput, our scheme minimises the video distortion of the received sequence. With the use of simple and local rate distortion measures and end-to-end distortion models at the video encoder, the proposed scheme estimates the received video distortion at the current transmission rate, as well as on the adjacent lower and higher rates. This allows the system to select the link-speed which offers the lowest distortion and to adapt to the channel conditions. Simulation results are presented using the MPEG-4/AVC H.264 video compression standard over IEEE 802.11g. The results show that the proposed system closely follows the optimum theoretic solution.

Structures and properties of spatially distorted porphyrins

International Nuclear Information System (INIS)

Golubchikov, Oleg A; Kuvshinova, Elizaveta M; Pukhovskaya, Svetlana G

2005-01-01

The published data on the structures and properties of porphyrins with distorted aromatic macrocycles are generalised and analysed. Data on the crystal structures, spectra and kinetics of formation and dissociation of their coordination derivatives are summarised. It is demonstrated that the distortion of the planar structure of the tetrapyrrole core is one of the most efficient means of controlling spectral, physicochemical and coordination properties of these compounds.

Effects Of Field Distortions In Ih-apf Linac

CERN Document Server

Kapin, Valery; Yamada, S

2004-01-01

The project on developing compact medical accelera-tors for the tumor therapy using carbon ions has been started at the National Institute of Radiological Sciences (NIRS). Alternating-phase-focused (APF) linac using an interdigital H-mode (IH) cavity has been proposed for the injector linac. The IH-cavity is doubly ridged circular resonator loaded by the drift-tubes mounted on ridges with supporting stems. The effects of intrinsic and random field distortions in a practical design of the 4-MeV/u 200 MHz IH-APF linac are considered. The intrinsic field distortions in IH-cavity are caused by the asymmetry of the gap field due to presence of the drift-tube supporting stems and pair of ridges. The random field distortions are caused by drift-tube misalignments and non-regular deviations of the voltage distribution from programmed law. The RF fields in IH-cavity have been calculated using Microwave Studio (MWS) code. The effects of field distortions on beam dynamics have been simulated numerically.

Expertise and processing distorted structure in chess.

Science.gov (United States)

Bartlett, James C; Boggan, Amy L; Krawczyk, Daniel C

2013-01-01

A classic finding in research on human expertise and knowledge is that of enhanced memory for stimuli in a domain of expertise as compared to either stimuli outside that domain, or within-domain stimuli that have been degraded or distorted in some way. However, we do not understand how experts process degradation or distortion of stimuli within the expert domain (e.g., a face with the eyes, nose, and mouth in the wrong positions, or a chessboard with pieces placed randomly). Focusing on the domain of chess, we present new fMRI evidence that when experts view such distorted/within-domain stimuli, they engage an active search for structure-a kind of exploratory chunking-that involves a component of a prefrontal-parietal network linked to consciousness, attention and working memory.

Could unstable relic particles distort the microwave background radiation?

International Nuclear Information System (INIS)

Dar, A.; Loeb, A.; Nussinov, S.

1989-01-01

Three general classes of possible scenarios for the recently reported distortion of the microwave background radiation (MBR) via decaying relic weakly interacting particles are analyzed. The analysis shows that such particles could not reheat the universe and cause the spectral distortion of the MBR. Gravitational processes such as the early formation of massive black holes may still be plausible energy sources for producing the reported spectral distortion of the MBR at an early cosmological epoch. 24 references

Anomalous Schottky specific heat and structural distortion in ferromagnetic PrAl2.

Science.gov (United States)

Pathak, Arjun K; Paudyal, D; Mudryk, Y; Gschneidner, K A; Pecharsky, V K

2013-05-03

Unique from other rare earth dialuminides, PrAl(2) undergoes a cubic to tetragonal distortion below T = 30 K in a zero magnetic field, but the system recovers its cubic symmetry upon the application of an external magnetic field of 10 kOe via a lifting of the 4f crystal field splitting. The nuclear Schottky specific heat in PrAl(2) is anomalously high compared to that of pure Pr metal. First principles calculations reveal that the 4f crystal field splitting in the tetragonally distorted phase of PrAl(2) underpins the observed unusual low temperature phenomena.

Characterization, prediction, and correction of geometric distortion in 3 T MR images

International Nuclear Information System (INIS)

Baldwin, Lesley N.; Wachowicz, Keith; Thomas, Steven D.; Rivest, Ryan; Gino Fallone, B.

2007-01-01

The work presented herein describes our methods and results for predicting, measuring and correcting geometric distortions in a 3 T clinical magnetic resonance (MR) scanner for the purpose of image guidance in radiation treatment planning. Geometric inaccuracies due to both inhomogeneities in the background field and nonlinearities in the applied gradients were easily visualized on the MR images of a regularly structured three-dimensional (3D) grid phantom. From a computed tomography scan, the locations of just under 10 000 control points within the phantom were accurately determined in three dimensions using a MATLAB-based computer program. MR distortion was then determined by measuring the corresponding locations of the control points when the phantom was imaged using the MR scanner. Using a reversed gradient method, distortions due to gradient nonlinearities were separated from distortions due to inhomogeneities in the background B 0 field. Because the various sources of machine-related distortions can be individually characterized, distortions present in other imaging sequences (for which 3D distortion cannot accurately be measured using phantom methods) can be predicted negating the need for individual distortion calculation for a variety of other imaging sequences. Distortions were found to be primarily caused by gradient nonlinearities and maximum image distortions were reported to be less than those previously found by other researchers at 1.5 T. Finally, the image slices were corrected for distortion in order to provide geometrically accurate phantom images

Jahn-Teller distortions, cation ordering and octahedral tilting in perovskites

International Nuclear Information System (INIS)

Lufaso, M.W.; Woodward, P.M.

2004-01-01

In transition metal oxides, preferential occupation of specific d orbitals on the transition metal ion can lead to the development of a long-range ordered pattern of occupied orbitals. This phenomenon, referred to as orbital ordering, is usually observed indirectly from the cooperative Jahn-Teller distortions (CJTDs) that result as a consequence of the orbital ordering. This paper examines the interplay between orbital ordering, octahedral tilting and cation ordering in perovskites. Both ternary AMX 3 perovskites containing an active Jahn-Teller (J-T) ion on the octahedral site and quaternary A 2 MM'X 6 perovskites containing a J-T ion on one-half of the octahedral sites have been examined. In AMX 3 perovskites, the tendency is for the occupied 3d 3x 2 -r 2 and 3d 3z 2 -r 2 orbitals to order in the ac plane, as exemplified by the crystal structures of LaMnO 3 and KCuF 3 . This arrangement maintains a favorable coordination environment for the anion sites. In AMX 3 perovskites, octahedral tilting tends to enhance the magnitude of the J-T distortions. In A 2 MM'X 6 perovskites, the tendency is for the occupied 3d 3z 2 -r 2 orbitals to align parallel to the c axis. This pattern maintains a favorable coordination environment about the symmetric M'-cation site. The orbital ordering found in rock-salt ordered A 2 MM'X 6 perovskites is compatible with octahedral rotations about the c axis (Glazer tilt system a 0 a 0 c - ) but appears to be incompatible with GdFeO 3 -type octahedral tilting (tilt system - b + a - ). (orig.)

Improvement of vector compensation method for vehicle magnetic distortion field

Energy Technology Data Exchange (ETDEWEB)

Pang, Hongfeng, E-mail: panghongfeng@126.com; Zhang, Qi; Li, Ji; Luo, Shitu; Chen, Dixiang; Pan, Mengchun; Luo, Feilu

2014-03-15

Magnetic distortions such as eddy-current field and low frequency magnetic field have not been considered in vector compensation methods. A new compensation method is proposed to suppress these magnetic distortions and improve compensation performance, in which the magnetic distortions related to measurement vectors and time are considered. The experimental system mainly consists of a three-axis fluxgate magnetometer (DM-050), an underwater vehicle and a proton magnetometer, in which the scalar value of magnetic field is obtained with the proton magnetometer and considered to be the true value. Comparing with traditional compensation methods, experimental results show that the magnetic distortions can be further reduced by two times. After compensation, error intensity and RMS error are reduced from 11684.013 nT and 7794.604 nT to 16.219 nT and 5.907 nT respectively. It suggests an effective way to improve the compensation performance of magnetic distortions. - Highlights: • A new vector compensation method is proposed for vehicle magnetic distortion. • The proposed model not only includes magnetometer error but also considers magnetic distortion. • Compensation parameters are computed directly by solving nonlinear equations. • Compared with traditional methods, the proposed method is not related with rotation angle rate. • Error intensity and RMS error can be reduced to 1/2 of the error with traditional methods.

Improvement of vector compensation method for vehicle magnetic distortion field

International Nuclear Information System (INIS)

Pang, Hongfeng; Zhang, Qi; Li, Ji; Luo, Shitu; Chen, Dixiang; Pan, Mengchun; Luo, Feilu

2014-01-01

Magnetic distortions such as eddy-current field and low frequency magnetic field have not been considered in vector compensation methods. A new compensation method is proposed to suppress these magnetic distortions and improve compensation performance, in which the magnetic distortions related to measurement vectors and time are considered. The experimental system mainly consists of a three-axis fluxgate magnetometer (DM-050), an underwater vehicle and a proton magnetometer, in which the scalar value of magnetic field is obtained with the proton magnetometer and considered to be the true value. Comparing with traditional compensation methods, experimental results show that the magnetic distortions can be further reduced by two times. After compensation, error intensity and RMS error are reduced from 11684.013 nT and 7794.604 nT to 16.219 nT and 5.907 nT respectively. It suggests an effective way to improve the compensation performance of magnetic distortions. - Highlights: • A new vector compensation method is proposed for vehicle magnetic distortion. • The proposed model not only includes magnetometer error but also considers magnetic distortion. • Compensation parameters are computed directly by solving nonlinear equations. • Compared with traditional methods, the proposed method is not related with rotation angle rate. • Error intensity and RMS error can be reduced to 1/2 of the error with traditional methods

Market distortions and aggregate productivity: Evidence from Chinese energy enterprises

International Nuclear Information System (INIS)

Dai, Xiaoyong; Cheng, Liwei

2016-01-01

Market distortions can generate resource misallocations across heterogeneous firms and reduce aggregate productivity. This paper measures market distortions and aggregate productivity growth in China's energy sector. We use the wedge between output elasticities and factor shares in revenues to recover a measure of firm-level market distortions. Using data on a large sample of Chinese energy enterprises from 1999 to 2007, our estimations provide strong evidence of the existence of both factor and product market distortions within and across China's various energy industries. The productivity aggregation and decomposition results demonstrate that the estimated aggregate productivity growth (APG) is, on average, 2.595% points per year, of which technological change, resource reallocation, and firm entries and exits account for 1.981, 0.068, and 0.546% points, respectively. The weak contributions of resource reallocation and firm turnover to APG are also found in energy sub-industries, except in the coal industry. Our research suggests that China's energy sector has major potential for productivity gains from resource reallocation through the reduction of market distortions. - Highlights: •We estimate market distortions and productivity growth of China's energy sector. •We use a large sample of Chinese energy enterprises. •There are evidences of the existence of factor and product market distortions. •Aggregate productivity growth is largely driven by firm-level technological change. •China's energy sector can realize productivity gains from resource reallocations.

Convergence of the Distorted Wave Born series

International Nuclear Information System (INIS)

MacMillan, D.S.

1981-01-01

The aim of this thesis is to begin to understand the idea of reaction mechanisms in nonrelativistic scattering systems. If we have a complete reaction theory of a particular scattering system, then we claim that the theory itself must contain information about important reaction mechanisms in the system. This information can be used to decide what reaction mechanisms should be included in an approximate calculation. To investigate this claim, we studied several solvable models. The primary concept employed in studying our models is the convergence of the multistep series generated by iterating the corresponding scattering integral equation. We known that the eigenvalues of the kernel of the Lippmann-Schwinger equation for potential scattering determine the rate of convergence of the Born series. The Born series will converge only if these eigenvalues all life within the unit circle. We extend these results to a study of the distorted wave Born series for inelastic scattering. The convergence criterion tells us when approximations are valid. We learn how the convergence of the distorted wave series depends upon energy, coupling constants, angular momentum, and angular momentum transfer. In one of our models, we look at several possible distorting potentials to see which one gives the best convergence. We have also applied our results to several actual DWBA or coupled channel calculations in the literature. In addition to the study of models of two-body scattering systems, we have considered the case of rearrangement scattering. We have discussed the formulation of (N greater than or equal to 3)-body distorted wave equations in which the interior dynamics have been redistributed by introducing compact N-body distortion potentials

Forensic image analysis - CCTV distortion and artefacts.

Science.gov (United States)

Seckiner, Dilan; Mallett, Xanthé; Roux, Claude; Meuwly, Didier; Maynard, Philip

2018-04-01

As a result of the worldwide deployment of surveillance cameras, authorities have gained a powerful tool that captures footage of activities of people in public areas. Surveillance cameras allow continuous monitoring of the area and allow footage to be obtained for later use, if a criminal or other act of interest occurs. Following this, a forensic practitioner, or expert witness can be required to analyse the footage of the Person of Interest. The examination ultimately aims at evaluating the strength of evidence at source and activity levels. In this paper, both source and activity levels are inferred from the trace, obtained in the form of CCTV footage. The source level alludes to features observed within the anatomy and gait of an individual, whilst the activity level relates to activity undertaken by the individual within the footage. The strength of evidence depends on the value of the information recorded, where the activity level is robust, yet source level requires further development. It is therefore suggested that the camera and the associated distortions should be assessed first and foremost and, where possible, quantified, to determine the level of each type of distortion present within the footage. A review of the 'forensic image analysis' review is presented here. It will outline the image distortion types and detail the limitations of differing surveillance camera systems. The aim is to highlight various types of distortion present particularly from surveillance footage, as well as address gaps in current literature in relation to assessment of CCTV distortions in tandem with gait analysis. Future work will consider the anatomical assessment from surveillance footage. Copyright © 2018 Elsevier B.V. All rights reserved.

The Impact of Agricultural Policy Distortions on the Productivity Gap: Evidence from the Rice Production

OpenAIRE

Rakotoarisoa, Manitra A.

2008-01-01

This study determines how production and trade policy distortions affected rice productivity in thirty-three rice-producing countries. A rice-productivity index for each country is constructed, and a model linking the productivity gap with policy distortions is presented. After controlling for the differences in infrastructure, openness, and human capital, this article shows that high subsidies and protection in developed countries combined with taxation of rice farming in poor countries have...

Helical Peierls distortion: Formation of helices of polyketone and polyisocyanide

Science.gov (United States)

Cui, Chang-Xing; Kertesz, Miklos

1990-06-01

A new type of Peierls-like distortion, the formation of a helix due to the existence of partially filled crossing bands, is reported for polyketone and polyisocyanide. The torsional potential curves, optimized geometries, band structures and phonon dispersion curves are derived. A comparison with the well-known Peierls-distorted all-trans polyacetylene indicates close similarity between the two types of Peierls distortions.

Effect of the structure distortion on the high photocatalytic performance of C{sub 60}/g-C{sub 3}N{sub 4} composite

Energy Technology Data Exchange (ETDEWEB)

Ma, Xiaojuan; Li, Xinru; Li, Mengmeng; Ma, Xiangchao; Yu, Lin, E-mail: yu-lin@sdu.edu.cn; Dai, Ying, E-mail: daiy60@sina.com

2017-08-31

Highlights: • The adsorption of C{sub 60} can induce an irreversible structure distortion for g-C{sub 3}N{sub 4} from flat to wrinkle. • The structure distortion of g-C{sub 3}N{sub 4} plays a crucial role in enhancing photocatalytic performances. • Stability, optical absorption and band edge all have positive correlations with wrinkle degree for g-C{sub 3}N{sub 4} monolayers. - Abstract: C{sub 60}/g-C{sub 3}N{sub 4} composite was reported experimentally to be of high photocatalytic activity in degrading organics. To investigate the underlying mechanism of high photocatalytic performance, the structural and electronic properties of g-C{sub 3}N{sub 4} monolayers with adsorbing and removing fullerene C{sub 60} are studied by means of density functional theory calculations. After 25 possible configurations examination, it is found that C{sub 60} prefers to stay upon the “junction nitrogen” with the carbon atom of fullerene being nearest to monolayers. Correspondingly, a type-I band alignment appears. Our results further demonstrate that the adsorption of C{sub 60} can lead to an irreversible structure distortion for g-C{sub 3}N{sub 4} from flat to wrinkle, which plays a crucial role in improving photocatalytic performance other than the separation of carriers at interface due to the formation of type-II heterojunctions as previous report. Compared to flat one, the light absorption of wrinkled structure shows augmented, the valence band maximum shifts towards lower position along with a stronger photo-oxidation capability. Interestingly, the results indicate that the energy, light absorption and band edge all have a particular relationship with wrinkle degree. The work presented here can be helpful to understand the mechanism behind the better photocatalytic performance for C{sub 60} modified g-C{sub 3}N{sub 4}.

Harmonic Distortion of Rectifier Topologies for Adjustable Speed Drives

DEFF Research Database (Denmark)

Hansen, Steffan

This thesis deals with the harmonic distortion of the diode rectifier and a number of alternative rectifier topologies for adjustable speed drives. The main intention of this thesis is to provide models and tools that allow easy prediction of the harmonic distortion of ASD’s in a given system...... rectifier are presented. The first level is an ideal model where the diode rectifier basically is treated as an independent (harmonic) current source. The second level is an empirical model, where simulated (or measured) values of the harmonic currents of the diode rectifier for different parameters......-angle of the individual harmonic currents of different diode rectifier types is analyzed. Four selected rectifier topologies with a high input power factor are presented. It is shown that using ac- or dc-coils is a very simple and efficient method to reduce the harmonic currents compared to the basic diode rectifier...

Jet Engine Fan Response to Inlet Distortions Generated by Ingesting Boundary Layer Flow

Science.gov (United States)

Giuliani, James Edward

Future civil transport designs may incorporate engines integrated into the body of the aircraft to take advantage of efficiency increases due to weight and drag reduction. Additional increases in engine efficiency are predicted if the inlets ingest the lower momentum boundary layer flow that develops along the surface of the aircraft. Previous studies have shown, however, that the efficiency benefits of Boundary Layer Ingesting (BLI) inlets are very sensitive to the magnitude of fan and duct losses, and blade structural response to the non-uniform flow field that results from a BLI inlet has not been studied in-depth. This project represents an effort to extend the modeling capabilities of TURBO, an existing rotating turbomachinery unsteady analysis code, to include the ability to solve the external and internal flow fields of a BLI inlet. The TURBO code has been a successful tool in evaluating fan response to flow distortions for traditional engine/inlet integrations. Extending TURBO to simulate the external and inlet flow field upstream of the fan will allow accurate pressure distortions that result from BLI inlet configurations to be computed and used to analyze fan aerodynamics and structural response. To validate the modifications for the BLI inlet flow field, an experimental NASA project to study flush-mounted S-duct inlets with large amounts of boundary layer ingestion was modeled. Results for the flow upstream and in the inlet are presented and compared to experimental data for several high Reynolds number flows to validate the modifications to the solver. Once the inlet modifications were validated, a hypothetical compressor fan was connected to the inlet, matching the inlet operating conditions so that the effect on the distortion could be evaluated. Although the total pressure distortion upstream of the fan was symmetrical for this geometry, the pressure rise generated by the fan blades was not, because of the velocity non-uniformity of the distortion

Characterization of tissue magnetic susceptibility-induced distortions for MRIgRT

International Nuclear Information System (INIS)

Stanescu, T.; Wachowicz, K.; Jaffray, D. A.

2012-01-01

Purpose: MR image geometric integrity is one of the building blocks of MRI-guided radiotherapy. In particular, tissue magnetic susceptibility-induced effects are patient-dependent and their behavior is difficult to assess and predict. In this study, the authors investigated in detail the characteristics of susceptibility (χ) distortions in the context of MRIgRT, including the case of two common MR-linac system configurations. Methods: The magnetic field distortions were numerically simulated for several imaging parameters and anatomical sites, i.e., brain, lung, pelvis (with air pockets), and prostate. The simulation process consisted of (a) segmentation of patient CT data into susceptibility relevant anatomical volumes (i.e., soft-tissue, bone and air/lung), (b) conversion of CT data into susceptibility masks by assigning bulk χ values to the structures defined at (a), (c) numerical computations of the local magnetic fields by using a finite difference algorithm, and (d) generation of the geometric distortion maps from the magnetic field distributions. For each patient anatomy, the distortions were quantified at the interfaces of anatomical structures with significantly different χ values. The analysis was performed for two specific orientations of the external main magnetic field (B 0 ) characteristic to the MR-linac systems, specifically along the z-axis for a bore MR scanner and in the (x,y)-plane for a biplanner magnet. The magnetic field local perturbations were reported in ppm. The metrics used to quantify the geometric distortions were the maximum, mean, and range of distortions. The numerical simulation algorithm was validated using phantom data measurements. Results: Susceptibility-induced distortions were determined for both quadratic and patient specific geometries. The numerical simulations showed a good agreement with the experimental data. The measurements were acquired at 1.5 and 3 T and with an encoding gradient varying between 3 and 20 mT/m by

Characterization of tissue magnetic susceptibility-induced distortions for MRIgRT.

Science.gov (United States)

Stanescu, T; Wachowicz, K; Jaffray, D A

2012-12-01

MR image geometric integrity is one of the building blocks of MRI-guided radiotherapy. In particular, tissue magnetic susceptibility-induced effects are patient-dependent and their behavior is difficult to assess and predict. In this study, the authors investigated in detail the characteristics of susceptibility (χ) distortions in the context of MRIgRT, including the case of two common MR-linac system configurations. The magnetic field distortions were numerically simulated for several imaging parameters and anatomical sites, i.e., brain, lung, pelvis (with air pockets), and prostate. The simulation process consisted of (a) segmentation of patient CT data into susceptibility relevant anatomical volumes (i.e., soft-tissue, bone and air∕lung), (b) conversion of CT data into susceptibility masks by assigning bulk χ values to the structures defined at (a), (c) numerical computations of the local magnetic fields by using a finite difference algorithm, and (d) generation of the geometric distortion maps from the magnetic field distributions. For each patient anatomy, the distortions were quantified at the interfaces of anatomical structures with significantly different χ values. The analysis was performed for two specific orientations of the external main magnetic field (B(0)) characteristic to the MR-linac systems, specifically along the z-axis for a bore MR scanner and in the (x,y)-plane for a biplanner magnet. The magnetic field local perturbations were reported in ppm. The metrics used to quantify the geometric distortions were the maximum, mean, and range of distortions. The numerical simulation algorithm was validated using phantom data measurements. Susceptibility-induced distortions were determined for both quadratic and patient specific geometries. The numerical simulations showed a good agreement with the experimental data. The measurements were acquired at 1.5 and 3 T and with an encoding gradient varying between 3 and 20 mT∕m by using an annular

In situ visualization of thermal distortions of synchrotron radiation optics

International Nuclear Information System (INIS)

Revesz, P.; Kazimirov, A.; Bazarov, I.

2007-01-01

We have developed a new in situ method to measure heating-induced distortions of the surface of the first monochromator crystal exposed to high-power white synchrotron radiation beam. The method is based on recording the image of a stationary grid of dots captured by a CCD camera as reflected from the surface of a crystal with and without a heat load. The three-dimensional surface profile (heat bump) is then reconstructed from the distortions of the original pattern. In experiments performed at the CHESS A2 wiggler beam line we measured the heat bumps with the heights of up to 600 nm produced by a wiggler beam with total power in the range of 15-60 W incident on the (1 1 1) Si crystal at various angles between 3 deg. and 15 deg

Shape distortion and dimensional precision in tungsten heavy alloy liquid phase sintering

International Nuclear Information System (INIS)

Wuwen Yi; German, R.M.; Lu, P.K.

2001-01-01

Microstructure effects on densification and shape distortion in liquid phase sintering of tungsten heavy alloy were investigated. Microstructure parameters such as the solid volume fraction, dihedral angle, initial porosity, and pore size were varied to measure densification and distortion behavior during LPS using W-Ni-Cu alloys. Green compacts were formed using ethylene-bis-stearamide as a pore-forming agent with the amount of polymer controlling the initial porosity. Different initial pore sizes were generated by varying the polymer particle size. Dihedral angle was varied by changing the Ni:Cu ratio in the alloys. Finally, the solid volume fraction was adjusted via the tungsten content. Distortion was quantified using profiles determined with a coordinate measuring machine to calculate a distortion parameter. Sintering results showed that solid volume fraction and dihedral angle are the dominant factors on densification and distortion during liquid phase sintering. Distortion decreases with increasing solid volume fraction and dihedral angle, while initial porosity and pore size have no observable effect on distortion at nearly full densification. Various strategies emerge to improve distortion control in liquid phase sintering. (author)

Distorted representation in visual tourism research

DEFF Research Database (Denmark)

Jensen, Martin Trandberg

2016-01-01

how photographic materialities, performativities and sensations contribute to new tourism knowledges. While highlighting the potential of distorted representation, the paper posits a cautionary note in regards to the influential role of academic journals in determining the qualities of visual data....... The paper exemplifies distorted representation through three impressionistic tales derived from ethnographic research on the European rail travel phenomenon: interrail.......Tourism research has recently been informed by non-representational theories to highlight the socio-material, embodied and heterogeneous composition of tourist experiences. These advances have contributed to further reflexivity and called for novel ways to animate representations...

Flat-field response and geometric distortion measurements of optical streak cameras

International Nuclear Information System (INIS)

Montgomery, D.S.; Drake, R.P.; Jones, B.A.; Wiedwald, J.D.

1987-08-01

To accurately measure pulse amplitude, shape, and relative time histories of optical signals with an optical streak camera, it is necessary to correct each recorded image for spatially-dependent gain nonuniformity and geometric distortion. Gain nonuniformities arise from sensitivity variations in the streak-tube photocathode, phosphor screen, image-intensifier tube, and image recording system. These nonuniformities may be severe, and have been observed to be on the order of 100% for some LLNL optical streak cameras. Geometric distortion due to optical couplings, electron-optics, and sweep nonlinearity not only affects pulse position and timing measurements, but affects pulse amplitude and shape measurements as well. By using a 1.053-μm, long-pulse, high-power laser to generate a spatially and temporally uniform source as input to the streak camera, the combined effects of flat-field response and geometric distortion can be measured under the normal dynamic operation of cameras with S-1 photocathodes. Additionally, by using the same laser system to generate a train of short pulses that can be spatially modulated at the input of the streak camera, we can effectively create a two-dimensional grid of equally-spaced pulses. This allows a dynamic measurement of the geometric distortion of the streak camera. We will discuss the techniques involved in performing these calibrations, will present some of the measured results for LLNL optical streak cameras, and will discuss software methods to correct for these effects. 6 refs., 6 figs

Operation of static series compensator under distorted utility conditions

DEFF Research Database (Denmark)

Awad, H.; Nelsen, H.; Blaabjerg, Frede

2005-01-01

in the case of distorted grid voltage. Furthermore, a selective harmonic compensation strategy is applied to filter out the grid harmonics. The operation of the SSC under distorted utility conditions and voltage dips is discussed. The validity of the proposed controller is verified by experiments, carried out...... on a 10-kV SSC laboratory setup. Experimental results have shown the ability of the SSC to mitigate voltage dips and harmonics. It is also shown that the proposed controller has improved the transient performance of the SSC even under distorted utility conditions....

Study Protocol on Intentional Distortion in Personality Assessment: Relationship with Test Format, Culture, and Cognitive Ability.

Science.gov (United States)

Van Geert, Eline; Orhon, Altan; Cioca, Iulia A; Mamede, Rui; Golušin, Slobodan; Hubená, Barbora; Morillo, Daniel

2016-01-01

Self-report personality questionnaires, traditionally offered in a graded-scale format, are widely used in high-stakes contexts such as job selection. However, job applicants may intentionally distort their answers when filling in these questionnaires, undermining the validity of the test results. Forced-choice questionnaires are allegedly more resistant to intentional distortion compared to graded-scale questionnaires, but they generate ipsative data. Ipsativity violates the assumptions of classical test theory, distorting the reliability and construct validity of the scales, and producing interdependencies among the scores. This limitation is overcome in the current study by using the recently developed Thurstonian item response theory model. As online testing in job selection contexts is increasing, the focus will be on the impact of intentional distortion on personality questionnaire data collected online. The present study intends to examine the effect of three different variables on intentional distortion: (a) test format (graded-scale versus forced-choice); (b) culture, as data will be collected in three countries differing in their attitudes toward intentional distortion (the United Kingdom, Serbia, and Turkey); and (c) cognitive ability, as a possible predictor of the ability to choose the more desirable responses. Furthermore, we aim to integrate the findings using a comprehensive model of intentional distortion. In the Anticipated Results section, three main aspects are considered: (a) the limitations of the manipulation, theoretical approach, and analyses employed; (b) practical implications for job selection and for personality assessment in a broader sense; and (c) suggestions for further research.

Distorted Risk Measures with Application to Military Capability Shortfalls

Science.gov (United States)

2005-12-15

effects of different distortions and to make basic recommendations regarding the appropriateness of certain distortion functions and parameters using...and increased limits ratemaking by proportional hazards transforms. Insurance: Mathematics and Economics, 17: 43-54. [9] Wang, S. (1996a). Premium

Time-Varying Distortions of Binaural Information by Bilateral Hearing Aids

Science.gov (United States)

Rodriguez, Francisco A.; Portnuff, Cory D. F.; Goupell, Matthew J.; Tollin, Daniel J.

2016-01-01

In patients with bilateral hearing loss, the use of two hearing aids (HAs) offers the potential to restore the benefits of binaural hearing, including sound source localization and segregation. However, existing evidence suggests that bilateral HA users’ access to binaural information, namely interaural time and level differences (ITDs and ILDs), can be compromised by device processing. Our objective was to characterize the nature and magnitude of binaural distortions caused by modern digital behind-the-ear HAs using a variety of stimuli and HA program settings. Of particular interest was a common frequency-lowering algorithm known as nonlinear frequency compression, which has not previously been assessed for its effects on binaural information. A binaural beamforming algorithm was also assessed. Wide dynamic range compression was enabled in all programs. HAs were placed on a binaural manikin, and stimuli were presented from an arc of loudspeakers inside an anechoic chamber. Stimuli were broadband noise bursts, 10-Hz sinusoidally amplitude-modulated noise bursts, or consonant–vowel–consonant speech tokens. Binaural information was analyzed in terms of ITDs, ILDs, and interaural coherence, both for whole stimuli and in a time-varying sense (i.e., within a running temporal window) across four different frequency bands (1, 2, 4, and 6 kHz). Key findings were: (a) Nonlinear frequency compression caused distortions of high-frequency envelope ITDs and significantly reduced interaural coherence. (b) For modulated stimuli, all programs caused time-varying distortion of ILDs. (c) HAs altered the relationship between ITDs and ILDs, introducing large ITD–ILD conflicts in some cases. Potential perceptual consequences of measured distortions are discussed. PMID:27698258

Distortion control in 20MnCr5 bevel gears after liquid nitriding process to maintain precision dimensions

Science.gov (United States)

Mahendiran, M.; Kavitha, M.

2018-02-01

Robotic and automotive gears are generally very high precision components with limitations in tolerances. Bevel gears are more widely used and dimensionally very close tolerance components that need stability without any backlash or distortion for smooth and trouble free functions. Nitriding is carried out to enhance wear resistance of the surface. The aim of this paper is to reduce the distortion in liquid nitriding process, though plasma nitriding is preferred for high precision components. Various trials were conducted to optimize the process parameters, considering pre dimensional setting for nominal nitriding layer growth. Surface cleaning, suitable fixtures and stress relieving operations were also done to optimize the process. Micro structural analysis and Vickers hardness testing were carried out for analyzing the phase changes, variation in surface hardness and case depth. CNC gear testing machine was used for determining the distortion level. The presence of white layer was found for about 10-15μm in the case depth of 250± 3.5μm showing an average surface hardness of 670 HV. Hence the economical liquid nitriding process was successfully used for producing high hardness and wear resistant coating over 20MnCr5 material with less distortion and reduced secondary grinding process for dimensional control.

Correction of distortions in a discontinuous image

International Nuclear Information System (INIS)

Geagan, M.J.; Chase, B.B.; Muehllehner, G.

1994-01-01

Large area position-sensitive NaI detectors have been successfully applied to positron emission tomography (PET). Typical PET studies involve detector singles rates in excess of 500 kcps, which can lead to pile-up and image degradation as a function of countrate. Better high countrate performance can be achieved with a local centroid algorithm, in which the position of each event is calculated from a small group of photomultipliers (PMTs) immediately surrounding the PMT with the highest signal (the peak PMT). The local centroid contains most of the light from the scintillation. If a local centroid of only seven PMTs is used, the position resolution becomes quite stable at high countrates, however, discontinuities appear in the detector flood image as events cluster around each PMT. We therefore developed a method for distortion correction of a discontinuous flood image. For each PMT on the detector, a peak PMT domain is defined. The peak PMT domain is the area on the detector where that PMT could have the highest signal. The peak PMT domains overlap slightly, so that all combinations of peak PMT and position are represented. A collimated source is moved through a regular grid of points - a template - over each peak PMT region. A short collection is performed at each point, and the real and measured position data are recorded. For each point in the spatial range of a given PMT, distortion correction offsets are computed by interpolating between the data points which correspond to that PMT. This new method has been implemented and evaluated. System resolution has been measured at low and high countrates. The high countrate resolution is better with the new method, with no degradation in low countrate resolution. The axial sensitivity profile is also more stable at high countrates, compared to the previously developed method. 3-D brain phantom images show a clear improvement in image quality at high countrates. ((orig.))

Two dimensional spatial distortion correction algorithm for scintillation GAMMA cameras

International Nuclear Information System (INIS)

Chaney, R.; Gray, E.; Jih, F.; King, S.E.; Lim, C.B.

1985-01-01

Spatial distortion in an Anger gamma camera originates fundamentally from the discrete nature of scintillation light sampling with an array of PMT's. Historically digital distortion correction started with the method based on the distortion measurement by using 1-D slit pattern and the subsequent on-line bi-linear approximation with 64 x 64 look-up tables for X and Y. However, the X, Y distortions are inherently two-dimensional in nature, and thus the validity of this 1-D calibration method becomes questionable with the increasing distortion amplitude in association with the effort to get better spatial and energy resolutions. The authors have developed a new accurate 2-D correction algorithm. This method involves the steps of; data collection from 2-D orthogonal hole pattern, 2-D distortion vector measurement, 2-D Lagrangian polynomial interpolation, and transformation to X, Y ADC frame. The impact of numerical precision used in correction and the accuracy of bilinear approximation with varying look-up table size have been carefully examined through computer simulation by using measured single PMT light response function together with Anger positioning logic. Also the accuracy level of different order Lagrangian polynomial interpolations for correction table expansion from hole centroids were investigated. Detailed algorithm and computer simulation are presented along with camera test results

A method to correct coordinate distortion in EBSD maps

International Nuclear Information System (INIS)

Zhang, Y.B.; Elbrønd, A.; Lin, F.X.

2014-01-01

Drift during electron backscatter diffraction mapping leads to coordinate distortions in resulting orientation maps, which affects, in some cases significantly, the accuracy of analysis. A method, thin plate spline, is introduced and tested to correct such coordinate distortions in the maps after the electron backscatter diffraction measurements. The accuracy of the correction as well as theoretical and practical aspects of using the thin plate spline method is discussed in detail. By comparing with other correction methods, it is shown that the thin plate spline method is most efficient to correct different local distortions in the electron backscatter diffraction maps. - Highlights: • A new method is suggested to correct nonlinear spatial distortion in EBSD maps. • The method corrects EBSD maps more precisely than presently available methods. • Errors less than 1–2 pixels are typically obtained. • Direct quantitative analysis of dynamic data are available after this correction

Anisotropic crystal structure distortion of the monoclinic polymorph of acetaminophen at high hydrostatic pressures.

Science.gov (United States)

Boldyreva, E V; Shakhtshneider, T P; Vasilchenko, M A; Ahsbahs, H; Uchtmann, H

2000-04-01

The anisotropy of structural distortion of the monoclinic polymorph of acetaminophen induced by hydrostatic pressure up to 4.0 GPa was studied by single-crystal X-ray diffraction in a Merrill-Bassett diamond anvil cell (DAC). The space group (P2(1)/n) and the general structural pattern remained unchanged with pressure. Despite the overall decrease in the molar volume with pressure, the structure expanded in particular crystallographic directions. One of the linear cell parameters (c) passed through a minimum as the pressure increased. The intramolecular bond lengths changed only slightly with pressure, but the changes in the dihedral and torsion angles were very large. The compressibility of the intermolecular hydrogen bonds NH...O and OH...O was measured. NH...O bonds were shown to be slightly more compressible than OH...O bonds. The anisotropy of structural distortion was analysed in detail in relation to the pressure-induced changes in the molecular conformations, to the compression of the hydrogen-bond network, and to the changes in the orientation of molecules with respect to each other in the pleated sheets in the structure. Dirichlet domains were calculated in order to analyse the relative shifts of the centroids of the hydrogen-bonded cycles and of the centroids of the benzene rings with pressure.

CMT scaling analysis and distortion evaluation in passive integral test facility

International Nuclear Information System (INIS)

Deng Chengcheng; Qin Benke; Wang Han; Chang Huajian

2013-01-01

Core makeup tank (CMT) is the crucial device of AP1000 passive core cooling system, and reasonable scaling analysis of CMT plays a key role in the design of passive integral test facilities. H2TS method was used to perform scaling analysis for both circulating mode and draining mode of CMT. And then, the similarity criteria for CMT important processes were applied in the CMT scaling design of the ACME (advanced core-cooling mechanism experiment) facility now being built in China. Furthermore, the scaling distortion results of CMT characteristic Ⅱ groups of ACME were calculated. At last, the reason of scaling distortion was analyzed and the distortion evaluation was conducted for ACME facility. The dominant processes of CMT circulating mode can be adequately simulated in the ACME facility, but the steam condensation process during CMT draining is not well preserved because the excessive CMT mass leads to more energy to be absorbed by cold metal. However, comprehensive analysis indicates that the ACME facility with high-pressure simulation scheme is able to properly represent CMT's important phenomena and processes of prototype nuclear plant. (authors)

Flat-field response and geometric distortion measurements of optical streak cameras

International Nuclear Information System (INIS)

Montgomery, D.S.; Drake, R.P.; Jones, B.A.; Wiedwald, J.D.

1987-01-01

To accurately measure pulse amplitude, shape, and relative time histories of optical signals with an optical streak camera, it is necessary to correct each recorded image for spatially-dependent gain nonuniformity and geometric distortion. Gain nonuniformities arise from sensitivity variations in the streak-tube photocathode, phosphor screen, image-intensifier tube, and image recording system. By using a 1.053-μm, long-pulse, high-power laser to generate a spatially and temporally uniform source as input to the streak camera, the combined effects of flat-field response and geometric distortion can be measured under the normal dynamic operation of cameras with S-1 photocathodes. Additionally, by using the same laser system to generate a train of short pulses that can be spatially modulated at the input of the streak camera, the authors can create a two-dimensional grid of equally-spaced pulses. This allows a dynamic measurement of the geometric distortion of the streak camera. The author discusses the techniques involved in performing these calibrations, present some of the measured results for LLNL optical streak cameras, and will discuss software methods to correct for these effects

Motivational Distortion on 16 PF Primaries by Male Felons.

Science.gov (United States)

Wallbrown, Fred H.; And Others

1989-01-01

Investigated motivational distortion using the 16 Personality Factor Questionnaire (16 PF) for male (n=331) criminal offenders. Results indicated that ego-strength, free-floating anxiety, ability to bind anxiety, boldness, dominance, emotional sensitivity and suspiciousness contributed most to the motivational distortion scale predictions.…

The psychological analysis of distortions of a behaviour of schoolboys living in various regions

International Nuclear Information System (INIS)

Furmanov, I.A.

1995-01-01

The necessity of compelled living on contaminated territory and the state social psychological disadaptation, connected with expectation of a remove to other regions, is the reason that the children are in a situation of a prolongation stress, destroying motivational, emotional, strong-willed and moral components of a behaviour regulation. It results to inadequate behaviour reactions to effects of social environment and varying conditions of activity. For the explanation of the reasons of a distortion of behaviour in a critical situation a psychological diagnostics of school teenagers living in the contamination and 'clear' regions was conducted, inter regional distinctions in the behaviour sphere of schoolboys are determined, psychological analysis of the main components of a regulation of a behaviour of teenagers with a various level of an aggressive is conducted. A psychological portrait of schoolboys with various types of behaviour distortions is received. Main directions of a correction work with various categories schoolboys are offered. 8 refs., 1 tab

Design of Solar PV Cell Based Inverter for Unbalanced and Distorted Industrial Loads

Directory of Open Access Journals (Sweden)

Naga Ananth D

2015-04-01

Full Text Available PV cell is getting importance in low and medium power generation due to easy installation, low maintenance and subsidies in price from respective nation. Most of the loads in distribution system are unbalanced and distorted, due to which there will be unbalanced voltage and current occur at load and may disturb its overall performance. Due to these loads voltage unbalance, distorted voltage and current and variable power factors in each phase can be observed. An efficient algorithm to mitigate unbalanced and distorted load and source voltage and current in solar photo voltaic (PV inverter for isolated load system was considered. This solar PV system can be applicable to remote located industrial loads like heating, welding and small arc furnace type distorted loads and also for unbalanced loads. The PV inverter is designed such that it will maintain nearly constant voltage magnitude and can mitigate harmonics in voltage and current near the load terminals. A MATLAB/ SIMULINK based solar PV inverter was simulated and results are compared with standard AC three phase grid connected system. The proposed shows that the inverter is having very less voltage and current harmonic content and can maintain nearly constant voltage profile for highly unbalanced system.

Mobile Watermarking against Geometrical Distortions

Directory of Open Access Journals (Sweden)

Jing Zhang

2015-08-01

Full Text Available Mobile watermarking robust to geometrical distortions is still a great challenge. In mobile watermarking, efficient computation is necessary because mobile devices have very limited resources due to power consumption. In this paper, we propose a low-complexity geometrically resilient watermarking approach based on the optimal tradeoff circular harmonic function (OTCHF correlation filter and the minimum average correlation energy Mellin radial harmonic (MACE-MRH correlation filter. By the rotation, translation and scale tolerance properties of the two kinds of filter, the proposed watermark detector can be robust to geometrical attacks. The embedded watermark is weighted by a perceptual mask which matches very well with the properties of the human visual system. Before correlation, a whitening process is utilized to improve watermark detection reliability. Experimental results demonstrate that the proposed watermarking approach is computationally efficient and robust to geometrical distortions.

Pump-induced optical distortions in disk amplifier modules: holographic and interferometric measurements

International Nuclear Information System (INIS)

Linford, G.J.; Chau, H.H.; Glaze, J.A.; Layne, C.B.; Rainer, F.

1975-01-01

Interferometric measurements have been made of the optical distortions induced in laser disk amplifiers during the flashlamp pumping pulse. Both conventional interferometric methods and the techniques of double exposure holographic interferometry were used to identify four major sources of pump-induced optical distortions: subsonic intrusion of hot gas (traced to leakage of atmospheric oxygen into the amplifier), microexplosions of dust particles, thermally induced optical distortions in the glass disks, and gaseous optical distortion effects caused by turbulent flow of the purging nitrogen gas supply used within the laser amplifier head. Methods for reducing or eliminating the effects of each of these optical distortions are described

Distortion of gravitational-wave packets due to their self-gravity

International Nuclear Information System (INIS)

Kocsis, Bence; Loeb, Abraham

2007-01-01

When a source emits a gravity-wave (GW) pulse over a short period of time, the leading edge of the GW signal is redshifted more than the inner boundary of the pulse. The GW pulse is distorted by the gravitational effect of the self-energy residing in between these shells. We illustrate this distortion for GW pulses from the final plunge of black hole binaries, leading to the evolution of the GW profile as a function of the radial distance from the source. The distortion depends on the total GW energy released ε and the duration of the emission τ, scaled by the total binary mass M. The effect should be relevant in finite box simulations where the waveforms are extracted within a radius of 2 M. For characteristic emission parameters at the final plunge between binary black holes of arbitrary spins, this effect could distort the simulated GW templates for LIGO and LISA by a fraction of 10 -3 . Accounting for the wave distortion would significantly decrease the waveform extraction errors in numerical simulations

Cognitive distortions among older adult gamblers in an Asian context.

Directory of Open Access Journals (Sweden)

Mythily Subramaniam

Full Text Available The study aims to describe the construct of cognitive distortions based on the narratives of older adult gamblers (aged 60 years and above in Singapore.Singapore residents (citizens or permanent residents aged 60 years and above, who were current or past regular gamblers were included in the study. Participants were recruited using a combination of venue based approach, referrals from service providers as well as by snowball sampling. In all, 25 in-depth interviews were conducted with older adult gamblers. The six-step thematic network analysis methodology was adopted for data analysis.The mean age of the participants was 66.2 years. The majority were male (n = 18, of Chinese ethnicity (n = 16, with a mean age of gambling initiation at 24.5 years. Among older adult gamblers, cognitive distortions emerged as a significant global theme comprising three organizing themes-illusion of control, probability control and interpretive control. The organizing themes comprised nine basic themes: perception of gambling as a skill, near miss, concept of luck, superstitious beliefs, entrapment, gambler's fallacy, chasing wins, chasing losses, and beliefs that wins are more than losses.Cognitive distortions were endorsed by all gamblers in the current study and were shown to play a role in both maintaining and escalating the gambling behaviour. While the surface characteristics of the distortions had a culture-specific appearance, the deeper characteristics of the distortions may in fact be more universal than previously thought. Future research must include longitudinal studies to understand causal relationships between cognitive distortions and gambling as well as the role of culture-specific distortions both in the maintenance and treatment of the disorder.

A CU-Level Rate and Distortion Estimation Scheme for RDO of Hardware-Friendly HEVC Encoders Using Low-Complexity Integer DCTs.

Science.gov (United States)

Lee, Bumshik; Kim, Munchurl

2016-08-01

In this paper, a low complexity coding unit (CU)-level rate and distortion estimation scheme is proposed for High Efficiency Video Coding (HEVC) hardware-friendly implementation where a Walsh-Hadamard transform (WHT)-based low-complexity integer discrete cosine transform (DCT) is employed for distortion estimation. Since HEVC adopts quadtree structures of coding blocks with hierarchical coding depths, it becomes more difficult to estimate accurate rate and distortion values without actually performing transform, quantization, inverse transform, de-quantization, and entropy coding. Furthermore, DCT for rate-distortion optimization (RDO) is computationally high, because it requires a number of multiplication and addition operations for various transform block sizes of 4-, 8-, 16-, and 32-orders and requires recursive computations to decide the optimal depths of CU or transform unit. Therefore, full RDO-based encoding is highly complex, especially for low-power implementation of HEVC encoders. In this paper, a rate and distortion estimation scheme is proposed in CU levels based on a low-complexity integer DCT that can be computed in terms of WHT whose coefficients are produced in prediction stages. For rate and distortion estimation in CU levels, two orthogonal matrices of 4×4 and 8×8 , which are applied to WHT that are newly designed in a butterfly structure only with addition and shift operations. By applying the integer DCT based on the WHT and newly designed transforms in each CU block, the texture rate can precisely be estimated after quantization using the number of non-zero quantized coefficients and the distortion can also be precisely estimated in transform domain without de-quantization and inverse transform required. In addition, a non-texture rate estimation is proposed by using a pseudoentropy code to obtain accurate total rate estimates. The proposed rate and the distortion estimation scheme can effectively be used for HW-friendly implementation of

Perceptual distortion analysis of color image VQ-based coding

Science.gov (United States)

Charrier, Christophe; Knoblauch, Kenneth; Cherifi, Hocine

1997-04-01

It is generally accepted that a RGB color image can be easily encoded by using a gray-scale compression technique on each of the three color planes. Such an approach, however, fails to take into account correlations existing between color planes and perceptual factors. We evaluated several linear and non-linear color spaces, some introduced by the CIE, compressed with the vector quantization technique for minimum perceptual distortion. To study these distortions, we measured contrast and luminance of the video framebuffer, to precisely control color. We then obtained psychophysical judgements to measure how well these methods work to minimize perceptual distortion in a variety of color space.

Cognitive distortions as a component and treatment focus of pathological gambling: a review.

Science.gov (United States)

Fortune, Erica E; Goodie, Adam S

2012-06-01

The literature on the role of cognitive distortions in the understanding and treatment of pathological gambling (PG) is reviewed, with sections focusing on (a) conceptual underpinnings of cognitive distortions, (b) cognitive distortions related to PG, (c) PG therapies that target cognitive distortions, (d) methodological factors and outcome variations, and (e) conclusions and prescriptive recommendations. The conceptual background for distortions related to PG lies in the program of heuristics and biases (Kahneman & Tversky, 1974) as well as other errors identified in basic psychology. The literature has focused on distortions arising from the representativeness heuristic (gambler's fallacy, overconfidence, and trends in number picking), the availability heuristic (illusory correlation, other individuals' wins, and inherent memory bias), and other sources (the illusion of control and double switching). Some therapies have incorporated cognitive restructuring within broader cognitive-behavioral therapies, with success. Other therapies have focused more narrowly on correcting distorted beliefs, more often with limited success. It is concluded that the literature establishes the role of cognitive distortions in PG and suggests therapies with particularly good promise, but is in need of further enrichment.

Spatial Distortion in MRI-Guided Stereotactic Procedures: Evaluation in 1.5-, 3- and 7-Tesla MRI Scanners.

Science.gov (United States)

Neumann, Jan-Oliver; Giese, Henrik; Biller, Armin; Nagel, Armin M; Kiening, Karl

2015-01-01

Magnetic resonance imaging (MRI) is replacing computed tomography (CT) as the main imaging modality for stereotactic transformations. MRI is prone to spatial distortion artifacts, which can lead to inaccuracy in stereotactic procedures. Modern MRI systems provide distortion correction algorithms that may ameliorate this problem. This study investigates the different options of distortion correction using standard 1.5-, 3- and 7-tesla MRI scanners. A phantom was mounted on a stereotactic frame. One CT scan and three MRI scans were performed. At all three field strengths, two 3-dimensional sequences, volumetric interpolated breath-hold examination (VIBE) and magnetization-prepared rapid acquisition with gradient echo, were acquired, and automatic distortion correction was performed. Global stereotactic transformation of all 13 datasets was performed and two stereotactic planning workflows (MRI only vs. CT/MR image fusion) were subsequently analysed. Distortion correction on the 1.5- and 3-tesla scanners caused a considerable reduction in positional error. The effect was more pronounced when using the VIBE sequences. By using co-registration (CT/MR image fusion), even a lower positional error could be obtained. In ultra-high-field (7 T) MR imaging, distortion correction introduced even higher errors. However, the accuracy of non-corrected 7-tesla sequences was comparable to CT/MR image fusion 3-tesla imaging. MRI distortion correction algorithms can reduce positional errors by up to 60%. For stereotactic applications of utmost precision, we recommend a co-registration to an additional CT dataset. © 2015 S. Karger AG, Basel.

Distortion of Probability and Outcome Information in Risky Decisions

Science.gov (United States)

DeKay, Michael L.; Patino-Echeverri, Dalia; Fischbeck, Paul S.

2009-01-01

Substantial evidence indicates that information is distorted during decision making, but very few studies have assessed the distortion of probability and outcome information in risky decisions. In two studies involving six binary decisions (e.g., banning blood donations from people who have visited England, because of "mad cow disease"),…

Audiovisual Cues and Perceptual Learning of Spectrally Distorted Speech

Science.gov (United States)

Pilling, Michael; Thomas, Sharon

2011-01-01

Two experiments investigate the effectiveness of audiovisual (AV) speech cues (cues derived from both seeing and hearing a talker speak) in facilitating perceptual learning of spectrally distorted speech. Speech was distorted through an eight channel noise-vocoder which shifted the spectral envelope of the speech signal to simulate the properties…

Distorted eikonal cross sections: A time-dependent view

International Nuclear Information System (INIS)

Turner, R.E.

1982-01-01

For Hamiltonians with two potentials, differential cross sections are written as time-correlation functions of reference and distorted transition operators. Distorted eikonal differential cross sections are defined in terms of straight-line and reference classical trajectories. Both elastic and inelastic results are obtained. Expressions for the inelastic cross sections are presented in terms of time-ordered cosine and sine memory functions through the use of the Zwanzig-Feshbach projection-operator method

Overcoming potential energy distortions in constrained internal coordinate molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Kandel, Saugat; Salomon-Ferrer, Romelia; Larsen, Adrien B.; Vaidehi, Nagarajan, E-mail: nvaidehi@coh.org [Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010 (United States); Jain, Abhinandan, E-mail: Abhi.Jain@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

2016-01-28

The Internal Coordinate Molecular Dynamics (ICMD) method is an attractive molecular dynamics (MD) method for studying the dynamics of bonded systems such as proteins and polymers. It offers a simple venue for coarsening the dynamics model of a system at multiple hierarchical levels. For example, large scale protein dynamics can be studied using torsional dynamics, where large domains or helical structures can be treated as rigid bodies and the loops connecting them as flexible torsions. ICMD with such a dynamic model of the protein, combined with enhanced conformational sampling method such as temperature replica exchange, allows the sampling of large scale domain motion involving high energy barrier transitions. Once these large scale conformational transitions are sampled, all-torsion, or even all-atom, MD simulations can be carried out for the low energy conformations sampled via coarse grained ICMD to calculate the energetics of distinct conformations. Such hierarchical MD simulations can be carried out with standard all-atom forcefields without the need for compromising on the accuracy of the forces. Using constraints to treat bond lengths and bond angles as rigid can, however, distort the potential energy landscape of the system and reduce the number of dihedral transitions as well as conformational sampling. We present here a two-part solution to overcome such distortions of the potential energy landscape with ICMD models. To alleviate the intrinsic distortion that stems from the reduced phase space in torsional MD, we use the Fixman compensating potential. To additionally alleviate the extrinsic distortion that arises from the coupling between the dihedral angles and bond angles within a force field, we propose a hybrid ICMD method that allows the selective relaxing of bond angles. This hybrid ICMD method bridges the gap between all-atom MD and torsional MD. We demonstrate with examples that these methods together offer a solution to eliminate the potential

The Dark Side of Context: Context Reinstatement Can Distort Memory.

Science.gov (United States)

Doss, Manoj K; Picart, Jamila K; Gallo, David A

2018-04-01

It is widely assumed that context reinstatement benefits memory, but our experiments revealed that context reinstatement can systematically distort memory. Participants viewed pictures of objects superimposed over scenes, and we later tested their ability to differentiate these old objects from similar new objects. Context reinstatement was manipulated by presenting objects on the reinstated or switched scene at test. Not only did context reinstatement increase correct recognition of old objects, but it also consistently increased incorrect recognition of similar objects as old ones. This false recognition effect was robust, as it was found in several experiments, occurred after both immediate and delayed testing, and persisted with high confidence even after participants were warned to avoid the distorting effects of context. To explain this memory illusion, we propose that context reinstatement increases the likelihood of confusing conceptual and perceptual information, potentially in medial temporal brain regions that integrate this information.

Spectral Behavior of Weakly Compressible Aero-Optical Distortions

Science.gov (United States)

Mathews, Edwin; Wang, Kan; Wang, Meng; Jumper, Eric

2016-11-01

In classical theories of optical distortions by atmospheric turbulence, an appropriate and key assumption is that index-of-refraction variations are dominated by fluctuations in temperature and the effects of turbulent pressure fluctuations are negligible. This assumption is, however, not generally valid for aero-optical distortions caused by turbulent flow over an optical aperture, where both temperature and pressures fluctuations may contribute significantly to the index-of-refraction fluctuations. A general expression for weak fluctuations in refractive index is derived using the ideal gas law and Gladstone-Dale relation and applied to describe the spectral behavior of aero-optical distortions. Large-eddy simulations of weakly compressible, temporally evolving shear layers are then used to verify the theoretical results. Computational results support theoretical findings and confirm that if the log slope of the 1-D density spectrum in the inertial range is -mρ , the optical phase distortion spectral slope is given by - (mρ + 1) . The value of mρ is then shown to be dependent on the ratio of shear-layer free-stream densities and bounded by the spectral slopes of temperature and pressure fluctuations. Supported by HEL-JTO through AFOSR Grant FA9550-13-1-0001 and Blue Waters Graduate Fellowship Program.

CMB spectral distortion constraints on thermal inflation

Energy Technology Data Exchange (ETDEWEB)

Cho, Kihyun; Stewart, Ewan D. [Department of Physics, KAIST, Daejeon 34141 (Korea, Republic of); Hong, Sungwook E. [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of); Zoe, Heeseung, E-mail: cho_physics@kaist.ac.kr, E-mail: heezoe@dgist.ac.kr, E-mail: jcap@profstewart.org, E-mail: heezoe@dgist.ac.kr [School of Undergraduate Studies, College of Transdisciplinary Studies, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988 (Korea, Republic of)

2017-08-01

Thermal inflation is a second epoch of exponential expansion at typical energy scales V {sup 1/4} ∼ 10{sup 6} {sup ∼} {sup 8} GeV. If the usual primordial inflation is followed by thermal inflation, the primordial power spectrum is only modestly redshifted on large scales, but strongly suppressed on scales smaller than the horizon size at the beginning of thermal inflation, k > k {sub b} = a {sub b} H {sub b}. We calculate the spectral distortion of the cosmic microwave background generated by the dissipation of acoustic waves in this context. For k {sub b} || 10{sup 3} Mpc{sup −1}, thermal inflation results in a large suppression of the μ-distortion amplitude, predicting that it falls well below the standard value of μ ≅ 2× 10{sup −8}. Thus, future spectral distortion experiments, similar to PIXIE, can place new limits on the thermal inflation scenario, constraining k {sub b} ∼> 10{sup 3} Mpc{sup −1} if μ ≅ 2× 10{sup −8} were found.

Distortion of digital panoramic radiographs used for implant site assessment

Directory of Open Access Journals (Sweden)

Rayyan Abdulhamid Kayal

2016-01-01

Full Text Available Aims: This study is conducted to determine the amount of distortion of digital panoramic radiographs. Materials and Methods: Panoramic radiographs of all patients who received dental implants in the years 2012 and 2013 were selected from the records at the faculty of dentistry, King Abdulaziz University. Radiographs were analyzed using the R4 Kodak Software for linear measurements of implants length and width. The measurements were compared to the actual size of the implant, and the amount of distortion was calculated. Results: A total of 169 implants were analyzed. Horizontally, there was a statistically significant increase of 0.4 mm in width in the radiographic measurement compared to the actual size in the incisor region. Vertically, the sample overall exhibited a decrease by 0.4 mm compared to the actual size. Incisors had the highest difference with a decrease of 1.7 mm in the radiographic measurements compared to actual size. The highest distortion was found in the incisor region for both diameter and length (1.1 and 0.86, respectively. Conclusion: Digital panoramic radiographs show minimal to no distortion. The highest distortion is found in the anterior area.

Face detection on distorted images using perceptual quality-aware features

Science.gov (United States)

Gunasekar, Suriya; Ghosh, Joydeep; Bovik, Alan C.

2014-02-01

We quantify the degradation in performance of a popular and effective face detector when human-perceived image quality is degraded by distortions due to additive white gaussian noise, gaussian blur or JPEG compression. It is observed that, within a certain range of perceived image quality, a modest increase in image quality can drastically improve face detection performance. These results can be used to guide resource or bandwidth allocation in a communication/delivery system that is associated with face detection tasks. A new face detector based on QualHOG features is also proposed that augments face-indicative HOG features with perceptual quality-aware spatial Natural Scene Statistics (NSS) features, yielding improved tolerance against image distortions. The new detector provides statistically significant improvements over a strong baseline on a large database of face images representing a wide range of distortions. To facilitate this study, we created a new Distorted Face Database, containing face and non-face patches from images impaired by a variety of common distortion types and levels. This new dataset is available for download and further experimentation at www.ideal.ece.utexas.edu/˜suriya/DFD/.

Surface temperature and distortion of optical elements exposed to high power synchrotron radiation beams

International Nuclear Information System (INIS)

Mourikis, S.; Jark, W.; Koch, E.E.; Saile, V.

1989-01-01

Mirrors made of various materials have been investigated under surface power densities of approximately 1--2 W/mm 2 emitted by a powerful hybrid wiggler installed in the 5.3-GeV DORIS storage ring. Thermal inhomogeneities and deformations at surfaces with a height resolution of 50 nm have been determined quantitatively. The only material withstanding these power levels without a significant deformation is SiC. Conventional cooling geometries are found to be useless for a reduction of the surface distortion

Analysis of tractable distortion metrics for EEG compression applications

International Nuclear Information System (INIS)

Bazán-Prieto, Carlos; Blanco-Velasco, Manuel; Cruz-Roldán, Fernando; Cárdenas-Barrera, Julián

2012-01-01

Coding distortion in lossy electroencephalographic (EEG) signal compression methods is evaluated through tractable objective criteria. The percentage root-mean-square difference, which is a global and relative indicator of the quality held by reconstructed waveforms, is the most widely used criterion. However, this parameter does not ensure compliance with clinical standard guidelines that specify limits to allowable noise in EEG recordings. As a result, expert clinicians may have difficulties interpreting the resulting distortion of the EEG for a given value of this parameter. Conversely, the root-mean-square error is an alternative criterion that quantifies distortion in understandable units. In this paper, we demonstrate that the root-mean-square error is better suited to control and to assess the distortion introduced by compression methods. The experiments conducted in this paper show that the use of the root-mean-square error as target parameter in EEG compression allows both clinicians and scientists to infer whether coding error is clinically acceptable or not at no cost for the compression ratio. (paper)

Applications of X-ray fluorescence holography to determine local lattice distortions

International Nuclear Information System (INIS)

Hayashi, Kouichi; Happo, Naohisa; Hosokawa, Shinya

2014-01-01

Highlights: • We summarized topics of X-ray fluorescence holography focused on the local lattice distortions. • We found details of behaviors of nearest neighbor atoms around dopants. • We found the average distributions of the atoms at the individual sites in mixed crystals. • Distorted and undistorted sires sometimes coexist in a same mixed crystal. - Abstract: X-ray fluorescence holography (XFH) is a method for investigating atomic order up to the medium ranges, and can provide 3D atomic images around specific elements within a radius of nm order. In addition to these characteristics, XFH is sensitive to positional fluctuations of atoms, and therefore it is useful for characterizing the local lattice distortions around specific elements. We have applied XFH to dopants and mixed crystals. We found interesting features in local lattice distortions, such as the displacements of first-neighbor atoms around dopants, far-sighted views of the atomistic fluctuations in mixed crystals, and the coexistence of distorted/undistorted sites in the same material

BioTwist : overcoming severe distortions in ridge-based biometrics for succesful identification

NARCIS (Netherlands)

Kotzerke, J.

2016-01-01

This thesis focuses on ridge-based and highly distorted biometrics, the different chal-lenges involved in a verification of identity scenario, and how to overcome them. More specifically, we work on ridge-based biometrics in two different contexts: (i) newborn and infant biometrics and (ii) quality

Perovskite LaPbMSbO6 (M=Co, Ni): Structural distortion, magnetic and dielectric properties

International Nuclear Information System (INIS)

Bai, Yijia; Han, Lin; Liu, Xiaojuan; Deng, Xiaolong; Wu, Xiaojie; Yao, Chuangang; Liang, Qingshuang; Meng, Junling; Meng, Jian

2014-01-01

The B-site ordered double perovskite oxides LaPbMSbO 6 (M=Co, Ni) have been synthesized via the modified Sol–Gel precursor two-step route. Rietveld refinements reveal strong abnormal structural distortion and BO 6 octahedral deformation appearing along the ab plane. Owing to the cooperative Jahn–Teller effect of Co 2+ and Pb 2+ ions, the Co-related compound exhibits almost complete Co 2+ –Sb 5+ order. For magnetic properties, spin-canted antiferromagnetic state with high extent of magnetic frustration is confirmed. The Ni-related compound presents heavier magnetic frustration for introducing tiny disorder on site occupation accompanied with valence state and further enhancing the complexity of magnetic competition. Dielectric measurements present a considerable temperature dependent dielectric relaxation with great dc-like loss feature in the LaPbCoSbO 6 . For LaPbNiSbO 6 , however, the permittivity with low dielectric loss is shown to be insensitive to either temperature or frequency. The corresponding electronic active energy manifests that the weakly bounded 3d-electron is prone to hop in a more distorted Co–Sb sublattice. - Graphical abstract: XRD Rietveld refinement result of LaPbCoSbO 6 presented a large BO 6 octahedral distortion along the ab plane. Based upon the variations from Co–O–Sb bond angles, a fierce competition from many extended magnetic coupling routes (M–O–O–M) would induce a considerably large magnetic frustration and electron hopping restriction. - Highlights: • Highly ordered LaPbMSbO 6 (M=Co, Ni) were synthesized. • Abnormal structural distortion appeared in the ab plane. • Strong magnetic frustration was confirmed via M 2+ –O–O–M 2+ route. • Dielectric measurements presented a large difference between Co and Ni samples. • 3d-electronic structure determines lattice distortion and physical properties

A Comparison of Three Methods for Measuring Distortion in Optical Windows

Science.gov (United States)

Youngquist, Robert C.; Nurge, Mark A.; Skow, Miles

2015-01-01

It's important that imagery seen through large-area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach, the distortion of an acrylic window is measured using three different methods: image comparison, moiré interferometry, and phase-shifting interferometry.

Advanced Engineering Methods for Assessing Welding Distortion in Aero-Engine Assemblies

International Nuclear Information System (INIS)

Jackson, Kathryn; Darlington, Roger

2011-01-01

Welding remains an attractive fabrication method for aero-engine assemblies, offering high production rates and reduced total cost, particularly for large complex assemblies. However, distortion generated during the welding process continues to provide a major challenge in terms of the control of geometric tolerances and residual stress. The welding distortion is influenced by the sequence and position of joints, the clamping configuration and the design of the assembly. For large complex assemblies the range of these options may be large. Hence the use of numerical simulation at an early stage of the product development process is valuable to enable a wide range of these factors to be explored with the aim of minimising welding distortions before production commences, and thereby reducing the product development time. In this paper, a new technique for simulation of welding distortions based on a shrinkage analysis is evaluated for an aero-engine assembly. The shrinkage simulations were built and solved using the ESI Group software Weld Planner. The rapid simulation speed enabled a wide range of welding plans to be explored, leading to recommendations for the fabrication process. The sensitivity of the model to mesh size and material properties is reported. The results of the shrinkage analysis were found to be similar to those of a transient analysis generated using ESI Group software SysWeld. The solution times were found to be significantly lower for the shrinkage analysis than the transient analysis. Hence it has been demonstrated that shrinkage analysis is a valuable tool for exploring the fabrication process of a welded assembly at an early stage of the product development process.

System performance enhancement with pre-distorted OOFDM signal waveforms in DM/DD systems.

Science.gov (United States)

Sánchez, C; Ortega, B; Capmany, J

2014-03-24

In this work we propose a pre-distortion technique for the mitigation of the nonlinear distortion present in directly modulated/detected OOFDM systems and explore the system performance achieved under varying system parameters. Simulation results show that the proposed pre-distortion technique efficiently mitigates the nonlinear distortion, achieving transmission information rates around 40 Gbits/s and 18.5 Gbits/s over 40 km and 100 km of single mode fiber links, respectively, under optimum operating conditions. Moreover, the proposed pre-distortion technique can potentially provide higher system performance to that obtained with nonlinear equalization at the receiver.

Effect of pion external distortion on low energy pion double-charge-exchange

International Nuclear Information System (INIS)

Khankhasaev, M.Kh.; Kurmanov, Zh.B.; Johnson, M.B.

1993-01-01

The effects of the external pion distortion for iso-elastic charge exchange scattering (within the framework of the isospin invariant optical model) is considered. An approximated method of taking into account the distortion based on the separable expansion of the optical potential in momentum space is developed. The result of external distortions for sequential scattering 14 C(π + , π - ) 14 O at 50 MeV is presented. It is shown that this distortion gives a small enhancement to forward and reduced the differential cross sections at large angels. 22 refs., 5 figs., 1 tab

Real-time distortion correction for visual inspection systems based on FPGA

Science.gov (United States)

Liang, Danhua; Zhang, Zhaoxia; Chen, Xiaodong; Yu, Daoyin

2008-03-01

Visual inspection is a kind of new technology based on the research of computer vision, which focuses on the measurement of the object's geometry and location. It can be widely used in online measurement, and other real-time measurement process. Because of the defects of the traditional visual inspection, a new visual detection mode -all-digital intelligent acquisition and transmission is presented. The image processing, including filtering, image compression, binarization, edge detection and distortion correction, can be completed in the programmable devices -FPGA. As the wide-field angle lens is adopted in the system, the output images have serious distortion. Limited by the calculating speed of computer, software can only correct the distortion of static images but not the distortion of dynamic images. To reach the real-time need, we design a distortion correction system based on FPGA. The method of hardware distortion correction is that the spatial correction data are calculated first under software circumstance, then converted into the address of hardware storage and stored in the hardware look-up table, through which data can be read out to correct gray level. The major benefit using FPGA is that the same circuit can be used for other circularly symmetric wide-angle lenses without being modified.

A method based on moving least squares for XRII image distortion correction

International Nuclear Information System (INIS)

Yan Shiju; Wang Chengtao; Ye Ming

2007-01-01

This paper presents a novel integrated method to correct geometric distortions of XRII (x-ray image intensifier) images. The method has been compared, in terms of mean-squared residual error measured at control and intermediate points, with two traditional local methods and a traditional global methods. The proposed method is based on the methods of moving least squares (MLS) and polynomial fitting. Extensive experiments were performed on simulated and real XRII images. In simulation, the effect of pincushion distortion, sigmoidal distortion, local distortion, noise, and the number of control points was tested. The traditional local methods were sensitive to pincushion and sigmoidal distortion. The traditional global method was only sensitive to sigmoidal distortion. The proposed method was found neither sensitive to pincushion distortion nor sensitive to sigmoidal distortion. The sensitivity of the proposed method to local distortion was lower than or comparable with that of the traditional global method. The sensitivity of the proposed method to noise was higher than that of all three traditional methods. Nevertheless, provided the standard deviation of noise was not greater than 0.1 pixels, accuracy of the proposed method is still higher than the traditional methods. The sensitivity of the proposed method to the number of control points was greatly lower than that of the traditional methods. Provided that a proper cutoff radius is chosen, accuracy of the proposed method is higher than that of the traditional methods. Experiments on real images, carried out by using a 9 in. XRII, showed that residual error of the proposed method (0.2544±0.2479 pixels) is lower than that of the traditional global method (0.4223±0.3879 pixels) and local methods (0.4555±0.3518 pixels and 0.3696±0.4019 pixels, respectively)

Object-based warping: an illusory distortion of space within objects.

Science.gov (United States)

Vickery, Timothy J; Chun, Marvin M

2010-12-01

Visual objects are high-level primitives that are fundamental to numerous perceptual functions, such as guidance of attention. We report that objects warp visual perception of space in such a way that spatial distances within objects appear to be larger than spatial distances in ground regions. When two dots were placed inside a rectangular object, they appeared farther apart from one another than two dots with identical spacing outside of the object. To investigate whether this effect was object based, we measured the distortion while manipulating the structure surrounding the dots. Object displays were constructed with a single object, multiple objects, a partially occluded object, and an illusory object. Nonobject displays were constructed to be comparable to object displays in low-level visual attributes. In all cases, the object displays resulted in a more powerful distortion of spatial perception than comparable non-object-based displays. These results suggest that perception of space within objects is warped.

Rate-distortion analysis of steganography for conveying stereovision disparity maps

Science.gov (United States)

Umeda, Toshiyuki; Batolomeu, Ana B. D. T.; Francob, Filipe A. L.; Delannay, Damien; Macq, Benoit M. M.

2004-06-01

3-D images transmission in a way which is compliant with traditional 2-D representations can be done through the embedding of disparity maps within the 2-D signal. This approach enables the transmission of stereoscopic video sequences or images on traditional analogue TV channels (PAL or NTSC) or printed photographic images. The aim of this work is to study the achievable performances of such a technique. The embedding of disparity maps has to be seen as a global rate-distortion problem. The embedding capacity through steganography is determined by the transmission channel noise and by the bearable distortion on the watermarked image. The distortion of the 3-D image displayed as two stereo views depends on the rate allocated to the complementary information required to build those two views from one reference 2-D image. Results from the works on the scalar Costa scheme are used to optimize the embedding of the disparity map compressed bit stream into the reference image. A method for computing the optimal trade off between the disparity map distortion and embedding distortion as a function of the channel impairments is proposed. The goal is to get a similar distortion on the left (the reference image) and the right (the disparity compensated image) images. We show that in typical situations the embedding of 2 bits/pixels in the left image, while the disparity map is compressed at 1 bit per pixel leads to a good trade-off. The disparity map is encoded with a strong error correcting code, including synchronisation bits.

Reluctance to express emotion explains relation between cognitive distortions and social competence in anxious children.

Science.gov (United States)

Scott, Brandon G; Pina, Armando A; Parker, Julia H

2017-12-12

Guided by social information processing and affective social competence models, the focal objective of this research was to examine the relations among anxious children's cognitive distortions, social skill competence, and reluctance to express emotion. In addition, we explored whether children's attention control played any meaningful role. Using a sample of 111 anxious children (M age  = 9.63, SD = 0.73; 75.7% girls; 56% Hispanic/Latino), we found that cognitive distortions were negatively related to social competence. In addition, tests of moderated mediation showed that the negative association between cognitive distortions and social skill competence was indirect via reluctance to express emotion, but this only was the case for anxious children with high attention control and for distortions in the academic domain. The findings of this study may set the stage for new ways to conceptualize the role of higher attention control among anxious youth. Statement of contribution What is already known on this subject? Cognitive errors are prevalent in anxious youth Anxious children show socio-emotion deficits What does this study add? Cognitive errors are related to socio-emotion deficits in anxious youth Relations depend on attention control. © 2017 The British Psychological Society.

Distortion Correction in Fetal EPI Using Non-Rigid Registration With a Laplacian Constraint.

Science.gov (United States)

Kuklisova-Murgasova, Maria; Lockwood Estrin, Georgia; Nunes, Rita G; Malik, Shaihan J; Rutherford, Mary A; Rueckert, Daniel; Hajnal, Joseph V

2018-01-01

Geometric distortion induced by the main B0 field disrupts the consistency of fetal echo planar imaging (EPI) data, on which diffusion and functional magnetic resonance imaging is based. In this paper, we present a novel data-driven method for simultaneous motion and distortion correction of fetal EPI. A motion-corrected and reconstructed T2 weighted single shot fast spin echo (ssFSE) volume is used as a model of undistorted fetal brain anatomy. Our algorithm interleaves two registration steps: estimation of fetal motion parameters by aligning EPI slices to the model; and deformable registration of EPI slices to slices simulated from the undistorted model to estimate the distortion field. The deformable registration is regularized by a physically inspired Laplacian constraint, to model distortion induced by a source-free background B0 field. Our experiments show that distortion correction significantly improves consistency of reconstructed EPI volumes with ssFSE volumes. In addition, the estimated distortion fields are consistent with fields calculated from acquired field maps, and the Laplacian constraint is essential for estimation of plausible distortion fields. The EPI volumes reconstructed from different scans of the same subject were more consistent when the proposed method was used in comparison with EPI volumes reconstructed from data distortion corrected using a separately acquired B0 field map.

Analyzing Reaction Rates with the Distortion/Interaction-Activation Strain Model

NARCIS (Netherlands)

Bickelhaupt, F. Matthias; Houk, Kendall N.

2017-01-01

The activation strain or distortion/interaction model is a tool to analyze activation barriers that determine reaction rates. For bimolecular reactions, the activation energies are the sum of the energies to distort the reactants into geometries they have in transition states plus the interaction

Redshift distortions of galaxy correlation functions

International Nuclear Information System (INIS)

Fry, J.N.; Florida Univ., Gainesville, FL; Gaztanaga, E.; Oxford Univ.

1993-01-01

To examine how peculiar velocities can affect the 2-, 3-, and 4-point correlation functions, we evaluate volume-average correlations for configurations that emphasize and minimize distortions for four different volume-limited samples from each of the CfA, SSRS, and IRAS redshift catalogs. We present the results as the correlation length r 0 and power index γ of the 2-point correlation, anti Ξ 2 = (r 0 /r) γ , and as the hierarchical amplitudes of the 3- and 4-point functions, S 3 = anti Ξ 3 /anti Ξ 2 2 and S 4 = anti Ξ/anti Ξ 2 3 . We find a characteristic distortion for anti Ξ 2 : The slope γ is flatter and the correlation length is larger in redshift space than in real space; that is, redshift distortions ''move'' correlations from small to large scales. At the largest scales, extra power in the redshift distribution is compatible with Ω 4/7 /b ∼ 1; we find 0.53 ± 0.15, 1.10 ± 0.16 and 0.84 ± 0.45 for the CfA, SSRS and IRAS catalogs. Higher order correlations anti Ξ 3 and anti Ξ 4 suffer similar redshift distortions, but in such a way that, within the accuracy of our analysis, the normalized amplitudes S 3 and S 4 are insensitive to this effect. The hierarchical amplitudes S 3 and S 4 are constant as a function of scale between 1-12 h -1 Mpc and have similar values in all samples and catalogues, S 3 ∼ 2 and S 4 ∼ 6, despite the fact that anti Ξ 2 , anti Ξ 3 , and anti Ξ 4 differ from one sample to another by large factors. The agreement between the independent estimations of S 3 and S 4 is remarkable given the different criteria in the selection of galaxies and also the difference in the resulting range of densities, luminosities and locations between samples

Spatial Precision in Magnetic Resonance Imaging–Guided Radiation Therapy: The Role of Geometric Distortion

Energy Technology Data Exchange (ETDEWEB)

Weygand, Joseph, E-mail: jw2899@columbia.edu [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas (United States); Fuller, Clifton David [The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas (United States); Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Ibbott, Geoffrey S. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas (United States); Mohamed, Abdallah S.R. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Clinical Oncology and Nuclear Medicine, Alexandria University, Alexandria (Egypt); Ding, Yao [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Yang, Jinzhong [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas (United States); Hwang, Ken-Pin [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Wang, Jihong [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas (United States)

2016-07-15

Because magnetic resonance imaging–guided radiation therapy (MRIgRT) offers exquisite soft tissue contrast and the ability to image tissues in arbitrary planes, the interest in this technology has increased dramatically in recent years. However, intrinsic geometric distortion stemming from both the system hardware and the magnetic properties of the patient affects MR images and compromises the spatial integrity of MRI-based radiation treatment planning, given that for real-time MRIgRT, precision within 2 mm is desired. In this article, we discuss the causes of geometric distortion, describe some well-known distortion correction algorithms, and review geometric distortion measurements from 12 studies, while taking into account relevant imaging parameters. Eleven of the studies reported phantom measurements quantifying system-dependent geometric distortion, while 2 studies reported simulation data quantifying magnetic susceptibility–induced geometric distortion. Of the 11 studies investigating system-dependent geometric distortion, 5 reported maximum measurements less than 2 mm. The simulation studies demonstrated that magnetic susceptibility–induced distortion is typically smaller than system-dependent distortion but still nonnegligible, with maximum distortion ranging from 2.1 to 2.6 mm at a field strength of 1.5 T. As expected, anatomic landmarks containing interfaces between air and soft tissue had the largest distortions. The evidence indicates that geometric distortion reduces the spatial integrity of MRI-based radiation treatment planning and likely diminishes the efficacy of MRIgRT. Better phantom measurement techniques and more effective distortion correction algorithms are needed to achieve the desired spatial precision.

Spatial Precision in Magnetic Resonance Imaging–Guided Radiation Therapy: The Role of Geometric Distortion

International Nuclear Information System (INIS)

Weygand, Joseph; Fuller, Clifton David; Ibbott, Geoffrey S.; Mohamed, Abdallah S.R.; Ding, Yao; Yang, Jinzhong; Hwang, Ken-Pin; Wang, Jihong

2016-01-01

Because magnetic resonance imaging–guided radiation therapy (MRIgRT) offers exquisite soft tissue contrast and the ability to image tissues in arbitrary planes, the interest in this technology has increased dramatically in recent years. However, intrinsic geometric distortion stemming from both the system hardware and the magnetic properties of the patient affects MR images and compromises the spatial integrity of MRI-based radiation treatment planning, given that for real-time MRIgRT, precision within 2 mm is desired. In this article, we discuss the causes of geometric distortion, describe some well-known distortion correction algorithms, and review geometric distortion measurements from 12 studies, while taking into account relevant imaging parameters. Eleven of the studies reported phantom measurements quantifying system-dependent geometric distortion, while 2 studies reported simulation data quantifying magnetic susceptibility–induced geometric distortion. Of the 11 studies investigating system-dependent geometric distortion, 5 reported maximum measurements less than 2 mm. The simulation studies demonstrated that magnetic susceptibility–induced distortion is typically smaller than system-dependent distortion but still nonnegligible, with maximum distortion ranging from 2.1 to 2.6 mm at a field strength of 1.5 T. As expected, anatomic landmarks containing interfaces between air and soft tissue had the largest distortions. The evidence indicates that geometric distortion reduces the spatial integrity of MRI-based radiation treatment planning and likely diminishes the efficacy of MRIgRT. Better phantom measurement techniques and more effective distortion correction algorithms are needed to achieve the desired spatial precision.

Evaluation of core distortion in FBR

International Nuclear Information System (INIS)

Ikarimoto, I.; Tanaka, M.; Okubo, Y.

1984-01-01

The analyses of FBR's core distortion are mainly performed in order to evaluate the following items: 1) Change of reactivity; 2) Force at pads on core assemblies; 3) Withdrawal force at refueling; 4) Loading, refueling and residual deviations of wrapper tubes (core assemblies) at the top; 5) Bowing modes of guide tubes for control rods. The analysis of core distortion are performed by using computer program for two-dimensional row deformation analysis or three-dimensional core deformation if necessary, considering these evaluated items which become design conditions. This report shows the relationship between core deformation analysis and component design, a point of view of choosing an analysis program for design considering core characteristics, and computing examples of core deformation of prototype class reactor by the above code. (author)

Lawful Distortion of Consumers’ Economic Behaviour

DEFF Research Database (Denmark)

Trzaskowski, Jan

2016-01-01

‘collateral damage’. In that vein this article discusses situations where consumers may have their economic behaviour distorted by commercial practices that are not unfair under the Directive. It is expected that many consumers will make relatively good decisions most of the time...... Visitors’). The article suggests how behavioural sciences may be applied to understand these situations in order to protect more consumers from having their economic behaviour distorted by commercial practices. It is suggested that per se prohibitions may be advantageous in some instances as long......The Unfair Commercial Practices Directive prohibits unfair business-to-consumer commercial practices with a view to protect consumers’ economic interests. In a market economy such regulation cannot protect the economic interests of all consumers in all situations – there must inevitably be some...

Redshift-space distortions from vector perturbations

Science.gov (United States)

Bonvin, Camille; Durrer, Ruth; Khosravi, Nima; Kunz, Martin; Sawicki, Ignacy

2018-02-01

We compute a general expression for the contribution of vector perturbations to the redshift space distortion of galaxy surveys. We show that they contribute to the same multipoles of the correlation function as scalar perturbations and should thus in principle be taken into account in data analysis. We derive constraints for next-generation surveys on the amplitude of two sources of vector perturbations, namely non-linear clustering and topological defects. While topological defects leave a very small imprint on redshift space distortions, we show that the multipoles of the correlation function are sensitive to vorticity induced by non-linear clustering. Therefore future redshift surveys such as DESI or the SKA should be capable of measuring such vector modes, especially with the hexadecapole which appears to be the most sensitive to the presence of vorticity.

Eigennoise Speech Recovery in Adverse Environments with Joint Compensation of Additive and Convolutive Noise

Directory of Open Access Journals (Sweden)

Trung-Nghia Phung

2015-01-01

Full Text Available The learning-based speech recovery approach using statistical spectral conversion has been used for some kind of distorted speech as alaryngeal speech and body-conducted speech (or bone-conducted speech. This approach attempts to recover clean speech (undistorted speech from noisy speech (distorted speech by converting the statistical models of noisy speech into that of clean speech without the prior knowledge on characteristics and distributions of noise source. Presently, this approach has still not attracted many researchers to apply in general noisy speech enhancement because of some major problems: those are the difficulties of noise adaptation and the lack of noise robust synthesizable features in different noisy environments. In this paper, we adopted the methods of state-of-the-art voice conversions and speaker adaptation in speech recognition to the proposed speech recovery approach applied in different kinds of noisy environment, especially in adverse environments with joint compensation of additive and convolutive noises. We proposed to use the decorrelated wavelet packet coefficients as a low-dimensional robust synthesizable feature under noisy environments. We also proposed a noise adaptation for speech recovery with the eigennoise similar to the eigenvoice in voice conversion. The experimental results showed that the proposed approach highly outperformed traditional nonlearning-based approaches.

Gambling Motives: Do They Explain Cognitive Distortions in Male Poker Gamblers?

Science.gov (United States)

Mathieu, Sasha; Barrault, Servane; Brunault, Paul; Varescon, Isabelle

2018-03-01

Gambling behavior is partly the result of varied motivations leading individuals to participate in gambling activities. Specific motivational profiles are found in gamblers, and gambling motives are closely linked to the development of cognitive distortions. This cross-sectional study aimed to predict cognitive distortions from gambling motives in poker players. The population was recruited in online gambling forums. Participants reported gambling at least once a week. Data included sociodemographic characteristics, the South Oaks Gambling Screen, the Gambling Motives Questionnaire-Financial and the Gambling-Related Cognition Scale. This study was conducted on 259 male poker gamblers (aged 18-69 years, 14.3% probable pathological gamblers). Univariate analyses showed that cognitive distortions were independently predicted by overall gambling motives (34.8%) and problem gambling (22.4%) (p gambling problems, showing a close inter-relationship between gambling motives, cognitive distortions and the severity of gambling. These data are consistent with the following theoretical process model: gambling motives lead individuals to practice and repeat the gambling experience, which may lead them to develop cognitive distortions, which in turn favor problem gambling. This study opens up new research perspectives to understand better the mechanisms underlying gambling practice and has clinical implications in terms of prevention and treatment. For example, a coupled motivational and cognitive intervention focused on gambling motives/cognitive distortions could be beneficial for individuals with gambling problems.

Archaeal Viruses from High-Temperature Environments.

Science.gov (United States)

Munson-McGee, Jacob H; Snyder, Jamie C; Young, Mark J

2018-02-27

Archaeal viruses are some of the most enigmatic viruses known, due to the small number that have been characterized to date. The number of known archaeal viruses lags behind known bacteriophages by over an order of magnitude. Despite this, the high levels of genetic and morphological diversity that archaeal viruses display has attracted researchers for over 45 years. Extreme natural environments, such as acidic hot springs, are almost exclusively populated by Archaea and their viruses, making these attractive environments for the discovery and characterization of new viruses. The archaeal viruses from these environments have provided insights into archaeal biology, gene function, and viral evolution. This review focuses on advances from over four decades of archaeal virology, with a particular focus on archaeal viruses from high temperature environments, the existing challenges in understanding archaeal virus gene function, and approaches being taken to overcome these limitations.

Archaeal Viruses from High-Temperature Environments

Directory of Open Access Journals (Sweden)

Jacob H. Munson-McGee

2018-02-01

Full Text Available Archaeal viruses are some of the most enigmatic viruses known, due to the small number that have been characterized to date. The number of known archaeal viruses lags behind known bacteriophages by over an order of magnitude. Despite this, the high levels of genetic and morphological diversity that archaeal viruses display has attracted researchers for over 45 years. Extreme natural environments, such as acidic hot springs, are almost exclusively populated by Archaea and their viruses, making these attractive environments for the discovery and characterization of new viruses. The archaeal viruses from these environments have provided insights into archaeal biology, gene function, and viral evolution. This review focuses on advances from over four decades of archaeal virology, with a particular focus on archaeal viruses from high temperature environments, the existing challenges in understanding archaeal virus gene function, and approaches being taken to overcome these limitations.

How Distorted Thinking Influence Arab Children Academic Achievement in Israel?

Science.gov (United States)

Gith, Emad

2018-01-01

The purpose of the current study was to examine the relation between the parents Cognitive Distortion and Arab children academic achievements in Israel. 52 fifth grade Arab Children and their parents from Israel were participated. The results indicated that parent's cognitive distortion related negatively to children academic achievements; there…

Learning-Based Just-Noticeable-Quantization- Distortion Modeling for Perceptual Video Coding.

Science.gov (United States)

Ki, Sehwan; Bae, Sung-Ho; Kim, Munchurl; Ko, Hyunsuk

2018-07-01

Conventional predictive video coding-based approaches are reaching the limit of their potential coding efficiency improvements, because of severely increasing computation complexity. As an alternative approach, perceptual video coding (PVC) has attempted to achieve high coding efficiency by eliminating perceptual redundancy, using just-noticeable-distortion (JND) directed PVC. The previous JNDs were modeled by adding white Gaussian noise or specific signal patterns into the original images, which were not appropriate in finding JND thresholds due to distortion with energy reduction. In this paper, we present a novel discrete cosine transform-based energy-reduced JND model, called ERJND, that is more suitable for JND-based PVC schemes. Then, the proposed ERJND model is extended to two learning-based just-noticeable-quantization-distortion (JNQD) models as preprocessing that can be applied for perceptual video coding. The two JNQD models can automatically adjust JND levels based on given quantization step sizes. One of the two JNQD models, called LR-JNQD, is based on linear regression and determines the model parameter for JNQD based on extracted handcraft features. The other JNQD model is based on a convolution neural network (CNN), called CNN-JNQD. To our best knowledge, our paper is the first approach to automatically adjust JND levels according to quantization step sizes for preprocessing the input to video encoders. In experiments, both the LR-JNQD and CNN-JNQD models were applied to high efficiency video coding (HEVC) and yielded maximum (average) bitrate reductions of 38.51% (10.38%) and 67.88% (24.91%), respectively, with little subjective video quality degradation, compared with the input without preprocessing applied.

On the relationship between perceptual impact of source and channel distortions in video sequences

DEFF Research Database (Denmark)

Korhonen, Jari; Reiter, Ulrich; You, Junyong

2010-01-01

It is known that peak signal-to-noise ratio (PSNR) can be used for assessing the relative qualities of distorted video sequences meaningfully only if the compared sequences contain similar types of distortions. In this paper, we propose a model for rough assessment of the bias in PSNR results, when...... video sequences with both channel and source distortion are compared against video sequences with source distortion only. The proposed method can be used to compare the relative perceptual quality levels of video sequences with different distortion types more reliably than using plain PSNR....

Metering error quantification under voltage and current waveform distortion

Science.gov (United States)

Wang, Tao; Wang, Jia; Xie, Zhi; Zhang, Ran

2017-09-01

With integration of more and more renewable energies and distortion loads into power grid, the voltage and current waveform distortion results in metering error in the smart meters. Because of the negative effects on the metering accuracy and fairness, it is an important subject to study energy metering combined error. In this paper, after the comparing between metering theoretical value and real recorded value under different meter modes for linear and nonlinear loads, a quantification method of metering mode error is proposed under waveform distortion. Based on the metering and time-division multiplier principles, a quantification method of metering accuracy error is proposed also. Analyzing the mode error and accuracy error, a comprehensive error analysis method is presented which is suitable for new energy and nonlinear loads. The proposed method has been proved by simulation.

Effect of orthorhombic distortion on dielectric and piezoelectric properties of CaBi4Ti4O15 ceramics

Science.gov (United States)

Tanwar, Amit; Sreenivas, K.; Gupta, Vinay

2009-04-01

High temperature bismuth layered piezoelectric and ferroelectric ceramics of CaBi4Ti4O15 (CBT) have been prepared using the solid state route. The formation of single phase material with orthorhombic structure was verified from x-ray diffraction and Raman spectroscopy. The orthorhombic distortion present in the CBT ceramic sintered at 1200 °C was found to be maximum. A sharp phase transition from ferroelectric to paraelectric was observed in the temperature dependent dielectric studies of all CBT ceramics. The Curie's temperature (Tc=790 °C) was found to be independent of measured frequency. The behavior of ac conductivity as a function of frequency (100 Hz-1 MHz) at low temperatures (<500 °C) follows the power law and is attributed to hopping conduction. The presence of large orthorhombic distortion in the CBT ceramic sintered at 1200 °C results in high dielectric constant, low dielectric loss, and high piezoelectric coefficient (d33). The observed results indicate the important role of orthorhombic distortion in determining the improved property of multicomponent ferroelectric material.

Distortions caused by the signal processing in analog AM modulators

International Nuclear Information System (INIS)

Njau, E.C.

1988-08-01

Complete analytical expressions for distortions caused by signal processing in analog AM modulators are developed. The salient features in these expressions are shown to be consistent with displays of actual spectra of AM signals. Finally suggestions are given on how the distortions may be practically minimized. (author). 6 refs, 3 figs

On distortions of TPC coordinates: inhomogeneities of electric and magnetic field

CERN Document Server

Dydak, F

2003-01-01

After a general discussion of electron drift in a gas volume with electric and magnetic fields, distortions in the r and r phi coordinates arising from inhomogeneities of the electric and magnetic fields in the HARP TPC are calculated. Inhomogeneities of the electric field arise from i) positive ions released by cosmic rays, ii) positive ions released by interaction secondaries, iii) positive ions released by beam muons, iv) positive ions released from beam particles downstream of the inner field cage, and v) a high voltage misalignment between the outer and inner field cages. Also, distortions arising from the inhomogeneity of the magnetic field are calculated. These effects resolve the controversy on unphysical numbers of 'wrong-charge' TPC tracks. The bad news are that effects are too big to be neglected. The good news are that, with enough sweat and tears, they can be adequately corrected.

Method and device for monitoring distortion in an optical network

NARCIS (Netherlands)

2012-01-01

A method and a device for monitoring of distortion in an optical network are provided, wherein at least one reference signal and at least one data signal are conveyed via an optical link and wherein a distortion of the at least one data signal is determined based on the at least one reference

Evaluation of effect of inlet distortion on aerodynamic performance of helium gas compressor for gas turbine high temperature reactor (GTHTR300). Contract research

International Nuclear Information System (INIS)

Takada, Shoji; Takizuka, Takakazu; Yan, Xing; Kurokouchi, Naohiro; Kunitomi, Kazuhiko

2006-02-01

Because the main pipe is connected perpendicular to the flow direction inside the distributing header in the inlet casing of the helium gas compressor design of GTHTR300, the main flow flowing into the header tends to separate from the header wall and to cause reverse flow, which increases flow resistance in the header. This phenomenon increases the total pressure loss in the header and inlet distortion, which is considered to deteriorate the aerodynamic performance of the compressor. Tests were carried out to evaluate the effects of inlet distortion on aerodynamic performance of compressor by using a 1/3-scale helium gas compressor model by varying a level of inlet distortion. Flow was injected from the wall of header to make circumferential velocities uniform before and after the reverse flow region to dissipate the separation and reverse flow. At the design point, inlet distortion was reduced by 2-3% by injection, which resulted in increasing adiabatic efficiency of blade section by 0.5%. A modified flow rate at surge point was lowered from 10.0 kg/s to 9.6 kg/s. At the same time, pressure loss of the inlet casing was reduced by 3-5 kPa, which is equivalent to adiabatic efficiency improvement around 0.8%. By setting orifice at the inlet of the inlet casing, the level of inlet distortion became 3% higher and the adiabatic efficiency of blade section became 1% higher at the design point. The modified flow rate at surge point increased from 10.6 to 10.9 kg/s. A new correlation between inlet distortion and adiabatic efficiency of blade section at the rated flow rate was derived based on compressor-in-parallel model and fitted to the test results. An overall adiabatic efficiency of full-scale compressor was predicted 90.2% based on the test results of efficiency and Reynolds number correlation, which was close to 89.7% that was predicted by test calibrated design through-flow code. (author)

Sudden distortion of turbulence at a forest edge

DEFF Research Database (Denmark)

Mann, Jakob; Dellwik, Ebba

2014-01-01

Dellwik et al. (2013) presented data from a forest edge experiment based on two meteorological towers instrumented with sonic anemometers. The experiment was performed at a dense edge of the Tromnæs Forest, which is a 24 m tall mature beech stand on the island Falster, Denmark. The topography...... in the lateral variance, whereas the streamwise variance remained approximately constant. This result is in contrast to the predictions by homogeneous rapid distortion theory. We apply and develop an alternative framework based on inhomogeneous rapid distortion theory, also called blocking, in combination...

Visualization and spectral synthesis of rotationally distorted stars

International Nuclear Information System (INIS)

Dall, T H; Sbordone, L

2011-01-01

Simple spherical, non-rotating stellar models are inadequate when describing real stars in the limit of very fast rotation: Both the observable spectrum and the geometrical shape of the star deviate strongly from simple models. We attempt to approach the problem of modeling geometrically distorted, rapidly rotating stars from a new angle: By constructing distorted geometrical models and integrating standard stellar models with varying temperature, gravity, and abundances, over the entire surface, we attempt a semi-empirical approach to modeling. Here we present our methodology, and present simple examples of applications.

Naked singularities are not singular in distorted gravity

Energy Technology Data Exchange (ETDEWEB)

Garattini, Remo, E-mail: Remo.Garattini@unibg.it [Università degli Studi di Bergamo, Facoltà di Ingegneria, Viale Marconi 5, 24044 Dalmine (Bergamo) (Italy); I.N.F.N. – sezione di Milano, Milan (Italy); Majumder, Barun, E-mail: barunbasanta@iitgn.ac.in [Indian Institute of Technology Gandhinagar, Ahmedabad, Gujarat 382424 (India)

2014-07-15

We compute the Zero Point Energy (ZPE) induced by a naked singularity with the help of a reformulation of the Wheeler–DeWitt equation. A variational approach is used for the calculation with Gaussian Trial Wave Functionals. The one loop contribution of the graviton to the ZPE is extracted keeping under control the UltraViolet divergences by means of a distorted gravitational field. Two examples of distortion are taken under consideration: Gravity's Rainbow and Noncommutative Geometry. Surprisingly, we find that the ZPE is no more singular when we approach the singularity.

Naked singularities are not singular in distorted gravity

Science.gov (United States)

Garattini, Remo; Majumder, Barun

2014-07-01

We compute the Zero Point Energy (ZPE) induced by a naked singularity with the help of a reformulation of the Wheele-DeWitt equation. A variational approach is used for the calculation with Gaussian Trial Wave Functionals. The one loop contribution of the graviton to the ZPE is extracted keeping under control the UltraViolet divergences by means of a distorted gravitational field. Two examples of distortion are taken under consideration: Gravity's Rainbow and Noncommutative Geometry. Surprisingly, we find that the ZPE is no more singular when we approach the singularity.

Naked singularities are not singular in distorted gravity

International Nuclear Information System (INIS)

Garattini, Remo; Majumder, Barun

2014-01-01

We compute the Zero Point Energy (ZPE) induced by a naked singularity with the help of a reformulation of the Wheeler–DeWitt equation. A variational approach is used for the calculation with Gaussian Trial Wave Functionals. The one loop contribution of the graviton to the ZPE is extracted keeping under control the UltraViolet divergences by means of a distorted gravitational field. Two examples of distortion are taken under consideration: Gravity's Rainbow and Noncommutative Geometry. Surprisingly, we find that the ZPE is no more singular when we approach the singularity

Structural versus electronic distortions of symmetry-broken IrTe$_2$

OpenAIRE

Kim, Hyo Sung; Kim, Tae-Hwan; Yang, Junjie; Cheong, Sang-Wook; Yeom, Han Woong

2014-01-01

We investigate atomic and electronic structures of the intriguing low temperature phase of IrTe2 using high-resolution scanning tunneling microscopy and spectroscopy. We confirm various stripe superstructures such as $\\times$3, $\\times$5, and $\\times$8. The strong vertical and lateral distortions of the lattice for the stripe structures are observed in agreement with recent calculations. The spatial modulations of electronic density of states are clearly identified as separated from the struc...

The selfish Segregation Distorter gene complex of Drosophila melanogaster.

Science.gov (United States)

Larracuente, Amanda M; Presgraves, Daven C

2012-09-01

Segregation Distorter (SD) is an autosomal meiotic drive gene complex found worldwide in natural populations of Drosophila melanogaster. During spermatogenesis, SD induces dysfunction of SD(+) spermatids so that SD/SD(+) males sire almost exclusively SD-bearing progeny rather than the expected 1:1 Mendelian ratio. SD is thus evolutionarily "selfish," enhancing its own transmission at the expense of its bearers. Here we review the molecular and evolutionary genetics of SD. Genetic analyses show that the SD is a multilocus gene complex involving two key loci--the driver, Segregation distorter (Sd), and the target of drive, Responder (Rsp)--and at least three upward modifiers of distortion. Molecular analyses show that Sd encodes a truncated duplication of the gene RanGAP, whereas Rsp is a large pericentromeric block of satellite DNA. The Sd-RanGAP protein is enzymatically wild type but mislocalized within cells and, for reasons that remain unclear, appears to disrupt the histone-to-protamine transition in drive-sensitive spermatids bearing many Rsp satellite repeats but not drive-insensitive spermatids bearing few or no Rsp satellite repeats. Evolutionary analyses show that the Sd-RanGAP duplication arose recently within the D. melanogaster lineage, exploiting the preexisting and considerably older Rsp satellite locus. Once established, the SD haplotype collected enhancers of distortion and suppressors of recombination. Further dissection of the molecular genetic and cellular basis of SD-mediated distortion seems likely to provide insights into several important areas currently understudied, including the genetic control of spermatogenesis, the maintenance and evolution of satellite DNAs, the possible roles of small interfering RNAs in the germline, and the molecular population genetics of the interaction of genetic linkage and natural selection.

Assessing Fan Flutter Stability in Presence of Inlet Distortion Using One-Way and Two-Way Coupled Methods

Science.gov (United States)

Herrick, Gregory P.

2014-01-01

Concerns regarding noise, propulsive efficiency, and fuel burn are inspiring aircraft designs wherein the propulsive turbomachines are partially (or fully) embedded within the airframe; such designs present serious concerns with regard to aerodynamic and aeromechanic performance of the compression system in response to inlet distortion. Previously, a preliminary design of a forward-swept high-speed fan exhibited flutter concerns in clean-inlet flows, and the present author then studied this fan further in the presence of off-design distorted in-flows. Continuing this research, a three-dimensional, unsteady, Navier-Stokes computational fluid dynamics code is again applied to analyze and corroborate fan performance with clean inlet flow and now with a simplified, sinusoidal distortion of total pressure at the aerodynamic interface plane. This code, already validated in its application to assess aerodynamic damping of vibrating blades at various flow conditions using a one-way coupled energy-exchange approach, is modified to include a two-way coupled timemarching aeroelastic simulation capability. The two coupling methods are compared in their evaluation of flutter stability in the presence of distorted in-flows.

Multiview Trajectory Mapping Using Homography with Lens Distortion Correction

Directory of Open Access Journals (Sweden)

Andrea Cavallaro

2008-11-01

Full Text Available We present a trajectory mapping algorithm for a distributed camera setting that is based on statistical homography estimation accounting for the distortion introduced by camera lenses. Unlike traditional approaches based on the direct linear transformation (DLT algorithm and singular value decomposition (SVD, the planar homography estimation is derived from renormalization. In addition to this, the algorithm explicitly introduces a correction parameter to account for the nonlinear radial lens distortion, thus improving the accuracy of the transformation. We demonstrate the proposed algorithm by generating mosaics of the observed scenes and by registering the spatial locations of moving objects (trajectories from multiple cameras on the mosaics. Moreover, we objectively compare the transformed trajectories with those obtained by SVD and least mean square (LMS methods on standard datasets and demonstrate the advantages of the renormalization and the lens distortion correction.

Multiview Trajectory Mapping Using Homography with Lens Distortion Correction

Directory of Open Access Journals (Sweden)

Kayumbi Gabin

2008-01-01

Full Text Available Abstract We present a trajectory mapping algorithm for a distributed camera setting that is based on statistical homography estimation accounting for the distortion introduced by camera lenses. Unlike traditional approaches based on the direct linear transformation (DLT algorithm and singular value decomposition (SVD, the planar homography estimation is derived from renormalization. In addition to this, the algorithm explicitly introduces a correction parameter to account for the nonlinear radial lens distortion, thus improving the accuracy of the transformation. We demonstrate the proposed algorithm by generating mosaics of the observed scenes and by registering the spatial locations of moving objects (trajectories from multiple cameras on the mosaics. Moreover, we objectively compare the transformed trajectories with those obtained by SVD and least mean square (LMS methods on standard datasets and demonstrate the advantages of the renormalization and the lens distortion correction.

Lepton asymmetry, neutrino spectral distortions, and big bang nucleosynthesis

Science.gov (United States)

Grohs, E.; Fuller, George M.; Kishimoto, C. T.; Paris, Mark W.

2017-03-01

We calculate Boltzmann neutrino energy transport with self-consistently coupled nuclear reactions through the weak-decoupling-nucleosynthesis epoch in an early universe with significant lepton numbers. We find that the presence of lepton asymmetry enhances processes which give rise to nonthermal neutrino spectral distortions. Our results reveal how asymmetries in energy and entropy density uniquely evolve for different transport processes and neutrino flavors. The enhanced distortions in the neutrino spectra alter the expected big bang nucleosynthesis light element abundance yields relative to those in the standard Fermi-Dirac neutrino distribution cases. These yields, sensitive to the shapes of the neutrino energy spectra, are also sensitive to the phasing of the growth of distortions and entropy flow with time/scale factor. We analyze these issues and speculate on new sensitivity limits of deuterium and helium to lepton number.

Time distortion for expert and novice online game players.

Science.gov (United States)

Rau, Pei-Luen Patrick; Peng, Shu-Yun; Yang, Chin-Chow

2006-08-01

Online game addiction is a new mental disorder. This disorder is difficult to describe because of its comprehensive nature. Many online game players have problems controlling their playing time. They cannot stop playing a game that they enjoy. This research surveyed the past literature on "flow" and time disorder theory. A time distortion experiment was conducted. This research invited 64 children, teenagers, and young adults to investigate player skill and playing time effects on online game break-off. The playing experience and degree of time distortion were measured and analyzed. The results showed that both novice and expert online game players were subject to time distortion. The participants had difficulty breaking off from the game without intrusion by others in the real world. This research also suggests eight questions for self-evaluation for online game addiction.

Intrinsic Local Distortions and charge carrier behavior in CMR manganites and cobaltites

Science.gov (United States)

Bridges, Frank

2010-03-01

We compare and contrast the local structure and electronic configurations in two oxide systems La1-xSrxCoO3 (LSCO) and La1-yCayMnO3 (LCMO). Although these oxides may appear quite similar they have rather different properties. At x=0, LaCoO3 (LCO) has unusual magnetic properties - diamagnetic at low T but developing a moment near 100K. The Sr doped LSCO materials show ferromagnetism for x > 0.2. For LCO, one of the possible spin state configurations called the intermediate spin (IS) state (S=1), should be Jahn-Teller (JT) active, while the low spin (S=0) and high spin (S=2) states have no JT distortion. Early local structure measurements suggested a JT distortion was present in LCO and therefore supported an IS spin model. However we find no evidence for any significant JT distortion (and hence no support for the IS model) for a range of bulk and nanoparticle cobaltites La1-xSrxCoO3, x = 0 - 0.35. In contrast there are large JT distortions in the manganites LCMO, 0.2 K-edge XANES data that shown no significant shift of the edge for the cobaltites as the Sr concentration increases from x =0 to 0.35 indicating essentially no change in the electronic configuration about Co; consequently, the holes introduced via Sr doping appear to go primarily into the O bands. In contrast there is a large shift of the Mn K-edge with Ca doping indicating a change in the average Mn valence, and a corresponding change in the Mn electronic configuration. We briefly discuss some possible models.

Distortion-Free 1-Bit PWM Coding for Digital Audio Signals

Directory of Open Access Journals (Sweden)

John Mourjopoulos

2007-01-01

Full Text Available Although uniformly sampled pulse width modulation (UPWM represents a very efficient digital audio coding scheme for digital-to-analog conversion and full-digital amplification, it suffers from strong harmonic distortions, as opposed to benign non-harmonic artifacts present in analog PWM (naturally sampled PWM, NPWM. Complete elimination of these distortions usually requires excessive oversampling of the source PCM audio signal, which results to impractical realizations of digital PWM systems. In this paper, a description of digital PWM distortion generation mechanism is given and a novel principle for their minimization is proposed, based on a process having some similarity to the dithering principle employed in multibit signal quantization. This conditioning signal is termed “jither” and it can be applied either in the PCM amplitude or the PWM time domain. It is shown that the proposed method achieves significant decrement of the harmonic distortions, rendering digital PWM performance equivalent to that of source PCM audio, for mild oversampling (e.g., ×4 resulting to typical PWM clock rates of 90 MHz.

Distortion-Free 1-Bit PWM Coding for Digital Audio Signals

Directory of Open Access Journals (Sweden)

Mourjopoulos John

2007-01-01

Full Text Available Although uniformly sampled pulse width modulation (UPWM represents a very efficient digital audio coding scheme for digital-to-analog conversion and full-digital amplification, it suffers from strong harmonic distortions, as opposed to benign non-harmonic artifacts present in analog PWM (naturally sampled PWM, NPWM. Complete elimination of these distortions usually requires excessive oversampling of the source PCM audio signal, which results to impractical realizations of digital PWM systems. In this paper, a description of digital PWM distortion generation mechanism is given and a novel principle for their minimization is proposed, based on a process having some similarity to the dithering principle employed in multibit signal quantization. This conditioning signal is termed "jither" and it can be applied either in the PCM amplitude or the PWM time domain. It is shown that the proposed method achieves significant decrement of the harmonic distortions, rendering digital PWM performance equivalent to that of source PCM audio, for mild oversampling (e.g., resulting to typical PWM clock rates of 90 MHz.

CIGS J-V distortion in the absence of blue photons

International Nuclear Information System (INIS)

Pudov, A.O.; Sites, J.R.; Contreras, M.A.; Nakada, T.; Schock, H.-W.

2005-01-01

Common buffer materials used with CuInGaSe 2 (CIGS) absorbers produce conduction-band barriers that may significantly distort the current-voltage (J-V) curves, especially when short-wavelength photons are excluded from the illumination spectrum. Earlier work documented this effect for CuInSe 2 (CIS) absorbers (band gap near 1.0 eV) with CdS buffers. Higher band-gap (no. approxno. 1.15 eV) CIGS absorbers show little or no distortion with CdS buffer layers. However, wider band gap (lower electron affinity) ZnS(O,OH) or InS(O,OH) buffers, prepared by chemical-bath deposition (CBD), clearly show the J-V distortion. The distortions have a turn-on time constant the order of a minute and turn-off time constant the order of a day, and they correlate with major variations in apparent quantum efficiency (QE) measured with varying intensity and spectral content of bias light. The results are consistent with a conduction-band spike barrier that increases with buffer band gap and is larger when the electron concentration in the buffer is small

Simulation of Distortion and Residual Stress Development During Heat Treatment of Steel Castings

Energy Technology Data Exchange (ETDEWEB)

Beckermann, Christoph; Carlson, Kent

2011-07-22

Heat treatment and associated processing, such as quenching, are critical during high strength steel casting production. These processes must be managed closely to prevent thermal and residual stresses that may result in distortion, cracking (particularly after machining), re-work, and weld repair. The risk of casting distortion limits aggressive quenching that can be beneficial to the process and yield an improved outcome. As a result of these distortions, adjustments must be made to the casting or pattern design, or tie bars must be added. Straightening castings after heat treatments can be both time-consuming and expensive. Residual stresses may reduce a casting's overall service performance, possibly resulting in catastrophic failure. Stress relieving may help, but expends additional energy in the process. Casting software is very limited in predicting distortions during heat treatment, so corrective measures most often involve a tedious trial-and-error procedure. An extensive review of existing heat treatment residual stress and distortion modeling revealed that it is vital to predict the phase transformations and microstructure of the steel along with the thermal stress development during heat treatment. After reviewing the state-of-the-art in heat treatment residual stress and distortion modeling, an existing commercial code was selected because of its advanced capabilities in predicting phase transformations, the evolving microstructure and related properties along with thermal stress development during heat treatment. However, this software was developed for small parts created from forgings or machined stock, and not for steel castings. Therefore, its predictive capabilities for heat treatment of steel castings were investigated. Available experimental steel casting heat treatment data was determined to be of insufficient detail and breadth, and so new heat treatment experiments were designed and performed, casting and heat treating modified versions

Models of brachial to finger pulse wave distortion and pressure decrement

NARCIS (Netherlands)

Gizdulich, P.; Prentza, A.; Wesseling, K.H.

1997-01-01

Objective: To model the pulse wave distortion and pressure decrement occurring between brachial and finger arteries. Distortion reversion and decrement correction were also our aims. Methods: Brachial artery pressure was recorded intra-arterially and finger pressure was recorded non-invasively by

Geometrical theory of nonlinear phase distortion of intense laser beams

International Nuclear Information System (INIS)

Glaze, J.A.; Hunt, J.T.; Speck, D.R.

1975-01-01

Phase distortion arising from whole beam self-focusing of intense laser pulses with arbitrary spatial profiles is treated in the limit of geometrical optics. The constant shape approximation is used to obtain the phase and angular distribution of the geometrical rays in the near field. Conditions for the validity of this approximation are discussed. Geometrical focusing of the aberrated beam is treated for the special case of a beam with axial symmetry. Equations are derived that show both the shift of the focus and the distortion of the intensity distribution that are caused by the nonlinear index of refraction of the optical medium. An illustrative example treats the case of beam distortion in a Nd:Glass amplifier

Reactivity analysis of core distortion effects in the FFTF

International Nuclear Information System (INIS)

Knutson, B.J.

1982-01-01

An improved technique for evaluating core distortion reactivity effects was developed using reactivity analyses of two core geometry models (R-Z and HEX). This technique is incorporated into a new processor code called CORDIS. The advantages of this technique over existing reactivity models are that is preserves core heterogeneity, provides a control rod insertion effect model, uses row-dependent axial shape functions, and provides a flexible and cost efficient core distortion reactivity analysis method

The main postulates of adaptive correction of distortions of the wave front in large-size optical systems

Directory of Open Access Journals (Sweden)

V. V. Sychev

2014-01-01

medium on the transmitted radiation WF;•  the lack of a reference source at the wavelength of trasnmitted laser radiation, which is required to implement methods for adaptive correction of the distorted WF;•  the unique to laser systems additional distorting factors available in transmission systems.These distorting factors include:• length of the optical path due to need in spatial diversity of high power laser source with a large number of matching optical elements;• thermal self-action of power laser radiation in the transport path of the radiation before its entry into forming optical system;• instability of spatio-temporal characteristics of the laser radiation source itself to take a turn for the worse conditions of radiation transmission both inside the optical path, and in the free atmosphere;• thermal irregularities and thermal deformation.It is shown that the adaptive systems differ from the active optics in that radiation wave front distortion is corrected in real time per totality of distorting factors (not only on the effect of the atmosphere with the speed ten times exceeding the effect of distortion itself. Here, the correction quality is estimated by criterion of the primary image quality.In this case, the correction continuously takes into account data about optical system parameters such as current space, temperature, time, and adjusting, thereby supporting the high quality of images under the action of distorting factors.The paper formulates and proposes the basic postulates of adaptive correction.Postulates are a set of statements and assertions, allowing us to implement effective means of adaptive correction of distortions.The paper also shows the real capabilities the methods and means of adaptive optics offer in case of efficient use of laser radiation power and what ways are possible to solve these tasks. First of all, these are:- forming a system of assumptions and minimization of distortions in the optical path, which includes a

The effect of redshift-space distortions on projected 2-pt clustering measurements

OpenAIRE

Nock, Kelly; Percival, Will J.; Ross, Ashley J.

2010-01-01

Although redshift-space distortions only affect inferred distances and not angles, they still distort the projected angular clustering of galaxy samples selected using redshift dependent quantities. From an Eulerian view-point, this effect is caused by the apparent movement of galaxies into or out of the sample. From a Lagrangian view-point, we find that projecting the redshift-space overdensity field over a finite radial distance does not remove all the anisotropic distortions. We investigat...

On the importance of adjusting for distorting factors in benchmarking analysis, as illustrated by a cost comparison of the different forms of implementation of the EU Packaging Directive.

Science.gov (United States)

Baum, Heinz-Georg; Schuch, Dieter

2017-12-01

Benchmarking is a proven and widely used business tool for identifying best practice. To produce robust results, the objects of comparison used in benchmarking analysis need to be structurally comparable and distorting factors need to be eliminated. We focus on a specific example - a benchmark study commissioned by the European Commission's Directorate-General for Environment on the implementation of Extended Producer Responsibility (EPR) for packaging at the national level - to discuss potential distorting factors and take them into account in the calculation. The cost of compliance per inhabitant and year, which is used as the key cost efficiency indicator in the study, is adjusted to take account of seven factors. The results clearly show that differences in performance may play a role, but the (legal) implementation of EPR - which is highly heterogeneous across countries - is the single most important cost determinant and must be taken into account to avoid misinterpretation and false conclusions.

Profile distortion by beam space-charge in Ionization Profile Monitors

CERN Document Server

Vilsmeier, D; Wettig, T

Measuring the transverse beam size in the Large Hadron Collider by using Ionization Profile Monitors is a difficult task for energies above injection during the energy ramp from 450 GeV to 6.5TeV. The beam size decreases from around 1mm to 200um and the brightness of the beam is high enough to destroy the structure of any form of interacting matter. While the electron trajectories are confined by an external electro-magnetic field which forces the electrons accordingly on helix paths with certain gyroradii, this gyration is heavily increased under the influence of the electric field of the beam. Smaller beam sizes, which go hand in hand with increased bunch electric fields, lead to larger gyroradii of the ionized electrons, which results in strongly distorted profiles. In addition, this distortion becomes more visible for smaller beam sizes as the extent of gyration grows compared to the actual beam size. Depending on the initial momentum distribution of the electrons, emerging from the ionization process wit...

Testing for Distortions in Performance Measures

DEFF Research Database (Denmark)

Sloof, Randolph; Van Praag, Mirjam

2015-01-01

Distorted performance measures in compensation contracts elicit suboptimal behavioral responses that may even prove to be dysfunctional (gaming). This paper applies the empirical test developed by Courty and Marschke (Review of Economics and Statistics, 90, 428-441) to detect whether the widely...

Testing for Distortions in Performance Measures

DEFF Research Database (Denmark)

Sloof, Randolph; Van Praag, Mirjam

Distorted performance measures in compensation contracts elicit suboptimal behavioral responses that may even prove to be dysfunctional (gaming). This paper applies the empirical test developed by Courty and Marschke (2008) to detect whether the widely used class of Residual Income based performa...

Aeromechanics Analysis of a Distortion-Tolerant Fan with Boundary Layer Ingestion

Science.gov (United States)

Bakhle, Milind A.; Reddy, T. S. R.; Coroneos, Rula M.; Min, James B.; Provenza, Andrew J.; Duffy, Kirsten P.; Stefko, George L.; Heinlein, Gregory S.

2018-01-01

A propulsion system with Boundary Layer Ingestion (BLI) has the potential to significantly reduce aircraft engine fuel burn. But a critical challenge is to design a fan that can operate continuously with a persistent BLI distortion without aeromechanical failure -- flutter or high cycle fatigue due to forced response. High-fidelity computational aeromechanics analysis can be very valuable to support the design of a fan that has satisfactory aeromechanic characteristics and good aerodynamic performance and operability. Detailed aeromechanics analyses together with careful monitoring of the test article is necessary to avoid unexpected problems or failures during testing. In the present work, an aeromechanics analysis based on a three-dimensional, time-accurate, Reynolds-averaged Navier-Stokes computational fluid dynamics code is used to study the performance and aeromechanical characteristics of the fan in both circumferentially-uniform and circumferentially-varying distorted flows. Pre-test aeromechanics analyses are used to prepare for the wind tunnel test and comparisons are made with measured blade vibration data after the test. The analysis shows that the fan has low levels of aerodynamic damping at various operating conditions examined. In the test, the fan remained free of flutter except at one near-stall operating condition. Analysis could not be performed at this low mass flow rate operating condition since it fell beyond the limit of numerical stability of the analysis code. The measured resonant forced response at a specific low-response crossing indicated that the analysis under-predicted this response and work is in progress to understand possible sources of differences and to analyze other larger resonant responses. Follow-on work is also planned with a coupled inlet-fan aeromechanics analysis that will more accurately represent the interactions between the fan and BLI distortion.

An Exact Formula for Calculating Inverse Radial Lens Distortions

Directory of Open Access Journals (Sweden)

Pierre Drap

2016-06-01

Full Text Available This article presents a new approach to calculating the inverse of radial distortions. The method presented here provides a model of reverse radial distortion, currently modeled by a polynomial expression, that proposes another polynomial expression where the new coefficients are a function of the original ones. After describing the state of the art, the proposed method is developed. It is based on a formal calculus involving a power series used to deduce a recursive formula for the new coefficients. We present several implementations of this method and describe the experiments conducted to assess the validity of the new approach. Such an approach, non-iterative, using another polynomial expression, able to be deduced from the first one, can actually be interesting in terms of performance, reuse of existing software, or bridging between different existing software tools that do not consider distortion from the same point of view.

Weld distortion prediction and control of the ITER vacuum vessel manufacturing mock-ups

International Nuclear Information System (INIS)

Ottolini, Marco; Barbensi, Andrea

2014-01-01

The fabrication of the ITER Vacuum Vessel Sectors is an unprecedented challenge, due to their dimensions, the close tolerances, the complex 'D' shape. The technological issues were faced by the production of full scale mock ups to confirm the manufacturing feasibility to achieve very tight tolerances and qualify the main manufacturing processes, by a step by step welding distortion control, by the qualification of not conventional NDT inspection techniques and by innovative 3D dimensional inspections. The Supplier is required to fabricate at least two mock ups, inboard and outboard, related to the manufacturing method of the VV Sectors, to demonstrate the control of the welding distortions to achieve tolerances, optimizing welding sequences and calibrating of welding distortions computer simulations. The stages of this preparatory activity are: prediction of welding distortion for fabrication mock ups representative of selected segments; demonstration that distortion predictions are consistent with experimental results from 3D dimensional inspection; understanding of reasons of possible deviations between numerical and experimental results and definition of action to solve these issues; demonstration that possible calculation simplifications, adopted to speed up the analysis process, do not affect significantly the welding distortion prediction. This paper describes the weld distortion prediction and control on the manufacturing mock-ups of ITER Vacuum Vessel Sectors, with particular emphasis to the lessons learned. (authors)

Analysis of Intermodulation Distortion in OFDM Based Transmitter Using EER Technique

Directory of Open Access Journals (Sweden)

S. Matejka

2016-06-01

Full Text Available During the last two decades, new digital modulation systems have appeared in the audio broadcasting. Such broadcasting systems require new transmitters’ concepts to enable the transmission of digitally modulated signals. Moreover, the selected modulation schemes (e.g. orthogonal frequency division multiplexing require a high linearity power stage, which typically exhibits low efficiency due to high peak-toaverage power ratio of the modulated signal. One of the promising transmitter concepts is the Kahn envelope elimination and restoration technique, where the original Cartesian in-phase and quadrature baseband signals are transformed to the envelope and phase signals. The main advantage of this technique is an ability to employ suitable types of highly efficient amplitude modulation transmitters for envelope amplification, while the phase modulated carrier is produced by an additional phase modulator. The substantial drawback of envelope elimination and restoration is nonideal recombination of linearly distorted amplitude signal and phase modulated carrier at the output power stage. The aim of this paper is twofold. Firstly, to analyze the effect of the envelope and phase signals bandwidth limitation on the modulated signal in-channel distortion and out-ofchannel emission. Secondly, to present the performance results as a reference for transmitter designers to properly set the envelope and phase paths to reach required in-channel signal quality and suppress out-of-channel products.

Electromagnetic pulse distortion in living tissue

NARCIS (Netherlands)

Lepelaars, E.S.A.M.

1996-01-01

Insight into the distortion of electromagnetic (EM) signals in living tissue is important for optimising medical applications. To obtain this insight, field calculations have been carried out for a plane-stratified configuration of air, skin, fat, muscle and bone tissue. In this configuration, an EM

Possible distortion of autoradiographic results

Energy Technology Data Exchange (ETDEWEB)

Kozlov, A.A.; Tumanushvili, G.D. (AN Gruzinskoj SSR, Tbilisi. Inst. Ehksperimental' noj Morfologii)

1980-01-01

The effect of radioactive labelling (H/sup 3/-thymidine) on the infusorian division is studied. The presented results show that introduction of labelled compounds results in accelerating infusorian cell division v. Thorough investigation of labelled compound effect with low activity on the parameters of cell division and the search of methods to eliminate distortions able to appear in autoradiographic experiments is expedient.

Investigation of the Geometrical Distortions in the Nuclear Emulsion

International Nuclear Information System (INIS)

Batusov, Yu.A.; Rumyantseva, V.P.; Soroko, L.M.; Tereshchenko, V.V.

1994-01-01

The geometrical distortions in the nuclear emulsion were investigated by means of two devices: 1) stereoscopic meso-optical Fourier transform microscope (MFTM) and 2) traditional optical microscope (KSM-1) designed for precise measurements. The particle tracks were produced by primary Oxygen-nuclei with impulse 65.6 GeV/c and by secondary α-particles in various regions of the nuclear emulsion. The measurement errors were: 1.8' (angular minute) for orientation angle θ xy ; 2.7' (angular minute) for dip angle θ z ; 0.3 μm for transverse coordinate x; 0.1 μm for longitudinal coordinate y and 0.3 μm for depth coordinate z. The effect of the global forced bending of the nuclear emulsion glass support was detected and estimated as dθ z /dy=2' (angular minute) per mm. To suppress the local geometrical distortions, a difference plot was calculated for two secondary α-particles going very close within ≤ 10 μm over the distance 6 mm. It was shown that this mode of the local geometrical distortions is kept constant over the mutual transverse distances up to 0.6 mm. By observing the zy-plots of four secondary α-particles we have isolated the rotating mode of the local geometrical distortions in the nuclear emulsion. 5 refs., 11 figs

Objective video quality assessment method for freeze distortion based on freeze aggregation

Science.gov (United States)

Watanabe, Keishiro; Okamoto, Jun; Kurita, Takaaki

2006-01-01

With the development of the broadband network, video communications such as videophone, video distribution, and IPTV services are beginning to become common. In order to provide these services appropriately, we must manage them based on subjective video quality, in addition to designing a network system based on it. Currently, subjective quality assessment is the main method used to quantify video quality. However, it is time-consuming and expensive. Therefore, we need an objective quality assessment technology that can estimate video quality from video characteristics effectively. Video degradation can be categorized into two types: spatial and temporal. Objective quality assessment methods for spatial degradation have been studied extensively, but methods for temporal degradation have hardly been examined even though it occurs frequently due to network degradation and has a large impact on subjective quality. In this paper, we propose an objective quality assessment method for temporal degradation. Our approach is to aggregate multiple freeze distortions into an equivalent freeze distortion and then derive the objective video quality from the equivalent freeze distortion. Specifically, our method considers the total length of all freeze distortions in a video sequence as the length of the equivalent single freeze distortion. In addition, we propose a method using the perceptual characteristics of short freeze distortions. We verified that our method can estimate the objective video quality well within the deviation of subjective video quality.

A content-based digital image watermarking scheme resistant to local geometric distortions

International Nuclear Information System (INIS)

Yang, Hong-ying; Chen, Li-li; Wang, Xiang-yang

2011-01-01

Geometric distortion is known as one of the most difficult attacks to resist, as it can desynchronize the location of the watermark and hence cause incorrect watermark detection. Geometric distortion can be decomposed into two classes: global affine transforms and local geometric distortions. Most countermeasures proposed in the literature only address the problem of global affine transforms. It is a challenging problem to design a robust image watermarking scheme against local geometric distortions. In this paper, we propose a new content-based digital image watermarking scheme with good visual quality and reasonable resistance against local geometric distortions. Firstly, the robust feature points, which can survive various common image processing and global affine transforms, are extracted by using a multi-scale SIFT (scale invariant feature transform) detector. Then, the affine covariant local feature regions (LFRs) are constructed adaptively according to the feature scale and local invariant centroid. Finally, the digital watermark is embedded into the affine covariant LFRs by modulating the magnitudes of discrete Fourier transform (DFT) coefficients. By binding the watermark with the affine covariant LFRs, the watermark detection can be done without synchronization error. Experimental results show that the proposed image watermarking is not only invisible and robust against common image processing operations such as sharpening, noise addition, and JPEG compression, etc, but also robust against global affine transforms and local geometric distortions

The role of self-serving cognitive distortions in reactive and proactive aggression.

Science.gov (United States)

Oostermeijer, Sanne; Smeets, Kirsten C; Jansen, Lucres M C; Jambroes, Tijs; Rommelse, Nanda N J; Scheepers, Floor E; Buitelaar, Jan K; Popma, Arne

2017-12-01

Aggression is often divided into reactive and proactive forms. Reactive aggression is typically thought to encompass 'blaming others' and 'assuming the worst', while proactive aggression relates to 'self-centeredness' and 'minimising/mislabelling'. Our aim was to evaluate relationships between reactive and proactive aggression and cognitive distortions and to test whether changes in these cognitions relate to changes in aggression. A total of 151 adolescents (60% boys; mean age 15.05 years, standard deviation 1.28) were enrolled in an evidence-based intervention to reduce aggression. Due to attrition and anomalous responses, the post-intervention sample involved 80 adolescents. Correlation and linear regression analyses were used to investigate the relationship between cognitive distortions and aggression. Blaming others was related to reactive aggression before the intervention, while all cognitive distortions were related to proactive aggression both pre- and post-intervention. Changes in reactive aggression were uniquely predicted by blaming others, while changes in proactive aggression were predicted by changes in cognitive distortions overall. To our knowledge, this study is the first to show a relationship between changes in cognitive distortions and changes in aggression. Treatment of reactive aggression may benefit from focusing primarily on reducing cognitive distortions involving misattribution of blame to others. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Distorted chain sites for Co- and Fe-substituted YBa2Cu3O/sub 7-δ/

International Nuclear Information System (INIS)

Bridges, F.; Boyce, J.B.; Claeson, T.; Geballe, T.H.; Tarascon, J.M.; Xerox Palo Alto Research Center, Palo Alto, California 94304; Physics Department, Chalmers University of Technology, S-41296 Gothenburg, Sweden; Department of Applied Physics, Stanford University, Stanford, California 94305; Bell Communications Research Laboratory, Red Bank, New Jersey 07701)

1989-01-01

We present x-ray-absorption fine-structure (XAFS) measurements for a series of Co- and Fe-substituted samples of YBa 2 Cu 3 O/sub 7-δ/(Y-Ba-Cu-O). Our analysis of the first- and second-neighbor environments indicates that the Co atoms primarily replace the Cu in the chain sites, the Cu(1) atoms, in Y-Ba-Cu-O, but many of these Co(1) sites and their neighboring oxygen sites are highly distorted. The first-neighbor Co-O peak consists of approximately 3.5 oxygen at 1.8 A and approximately 1.3 oxygen at 2.4 A, while the second-neighbor multipeak in the XAFS data is unexpectedly low in amplitude. Structure in this peak is inconsistent with a simple Gaussian broadening and indicates that several Co(1)-Ba distances exist. We propose an aggregation of the Co atoms into distorted, zigzag chains along the directions, with some of the Co displaced off center by approximately 0.4 A along a perpendicular direction. This model is consistent with the second-neighbor XAFS data, provides an explanation for the tetragonal structure via twinning on a microscopic scale, and accommodates excess oxygen within the Co chains. The Fe data suggest that similar chains also exist in the Fe-substituted samples. There are, however, some differences between the local environments of the Fe and Co. The primary difference is that a small but significant number of Fe atoms occupy the Cu(2) plane sites while no appreciable number of Co atoms are found on the Cu(2) sites in the more dilute samples. Finally, near-edge measurements on the Co and Fe K-absorption edges indicate that the valence is primarily +3, but a mixture of valences exists. For Co the edge position corresponds to a mixture of +2 and +3 valences, while Fe exists in a mixture of +2, +3, and +4 states

Forced Response Analysis of a Fan with Boundary Layer Inlet Distortion

Science.gov (United States)

Bakhle, Milind A.; Reddy, T. S. R.; Coroneos, Rula M.

2014-01-01

Boundary layer ingesting propulsion systems have the potential to significantly reduce fuel burn for future generations of commercial aircraft, but these systems must be designed to overcome the challenge of high dynamic stresses in fan blades due to forced response. High dynamic stresses can lead to high cycle fatigue failures. High-fidelity computational analysis of the fan aeromechanics is integral to an ongoing effort to design a boundary layer ingesting inlet and fan for a wind-tunnel test. An unsteady flow solution from a Reynoldsaveraged Navier Stokes analysis of a coupled inlet-fan system is used to calculate blade unsteady loading and assess forced response of the fan to distorted inflow. Conducted prior to the mechanical design of a fan, the initial forced response analyses performed in this study provide an early look at the levels of dynamic stresses that are likely to be encountered. For the boundary layer ingesting inlet, the distortion contains strong engine order excitations that act simultaneously. The combined effect of these harmonics was considered in the calculation of the forced response stresses. Together, static and dynamic stresses can provide the information necessary to evaluate whether the blades are likely to fail due to high cycle fatigue. Based on the analyses done, the overspeed condition is likely to result in the smallest stress margin in terms of the mean and alternating stresses. Additional work is ongoing to expand the analyses to off-design conditions, on-resonance conditions, and to include more detailed modeling of the blade structure.

Distortion Analysis Toolkit—A Software Tool for Easy Analysis of Nonlinear Audio Systems

Directory of Open Access Journals (Sweden)

Jyri Pakarinen

2010-01-01

Full Text Available Several audio effects devices deliberately add nonlinear distortion to the processed signal in order to create a desired sound. When creating virtual analog models of nonlinearly distorting devices, it would be very useful to carefully analyze the type of distortion, so that the model could be made as realistic as possible. While traditional system analysis tools such as the frequency response give detailed information on the operation of linear and time-invariant systems, they are less useful for analyzing nonlinear devices. Furthermore, although there do exist separate algorithms for nonlinear distortion analysis, there is currently no unified, easy-to-use tool for rapid analysis of distorting audio systems. This paper offers a remedy by introducing a new software tool for easy analysis of distorting effects. A comparison between a well-known guitar tube amplifier and two commercial software simulations is presented as a case study. This freely available software is written in Matlab language, but the analysis tool can also run as a standalone program, so the user does not need to have Matlab installed in order to perform the analysis.

Distorted Images of Islam: The Case of Former Yugoslavia

Directory of Open Access Journals (Sweden)

Fikret Karčić

1995-12-01

Full Text Available Since the 1980s, the former Yugoslavia has witnessed increasing distortion of images of Islam in academic publications, media, and public life. This process has been connected with the changes in power structure in Serbia, and with the new ideological orientation of the Serbian leadership which opted for national exclusivism (ethno fascism. The Muslims have been portrayed as a threat to the realization of the Serbian hegemonist project. In order to mobilize domestic public opinion against the Muslims and to justify future acts against them in the eyes of the West, the Serbian leadership needed an image of Islam as a totalitarian, inherently violent, and culturally alien system on European soil. Such a distorted image has been provided by some influential Serbian orientalists, the Orthodox Church, and some historians. Due to these distortions, these Serbian intellectual circles have become accomplices in the crimes committed against the Muslims in former Yugoslavia during 1992-1995.

Perovskite LaPbMSbO{sub 6} (M=Co, Ni): Structural distortion, magnetic and dielectric properties

Energy Technology Data Exchange (ETDEWEB)

Bai, Yijia [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China); Chemical Engineering College, Inner Mongolia University of Technology, 49 Aimin Street, Hohhot 010051 (China); Han, Lin [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China); University of Chinese Academy of Sciences, Beijing 10049 (China); Liu, Xiaojuan, E-mail: lxjuan@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China); Deng, Xiaolong [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China); University of Chinese Academy of Sciences, Beijing 10049 (China); Wu, Xiaojie [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China); Yao, Chuangang; Liang, Qingshuang; Meng, Junling [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China); University of Chinese Academy of Sciences, Beijing 10049 (China); Meng, Jian, E-mail: jmeng@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022 (China)

2014-09-15

The B-site ordered double perovskite oxides LaPbMSbO{sub 6} (M=Co, Ni) have been synthesized via the modified Sol–Gel precursor two-step route. Rietveld refinements reveal strong abnormal structural distortion and BO{sub 6} octahedral deformation appearing along the ab plane. Owing to the cooperative Jahn–Teller effect of Co{sup 2+} and Pb{sup 2+} ions, the Co-related compound exhibits almost complete Co{sup 2+}–Sb{sup 5+} order. For magnetic properties, spin-canted antiferromagnetic state with high extent of magnetic frustration is confirmed. The Ni-related compound presents heavier magnetic frustration for introducing tiny disorder on site occupation accompanied with valence state and further enhancing the complexity of magnetic competition. Dielectric measurements present a considerable temperature dependent dielectric relaxation with great dc-like loss feature in the LaPbCoSbO{sub 6}. For LaPbNiSbO{sub 6}, however, the permittivity with low dielectric loss is shown to be insensitive to either temperature or frequency. The corresponding electronic active energy manifests that the weakly bounded 3d-electron is prone to hop in a more distorted Co–Sb sublattice. - Graphical abstract: XRD Rietveld refinement result of LaPbCoSbO{sub 6} presented a large BO{sub 6} octahedral distortion along the ab plane. Based upon the variations from Co–O–Sb bond angles, a fierce competition from many extended magnetic coupling routes (M–O–O–M) would induce a considerably large magnetic frustration and electron hopping restriction. - Highlights: • Highly ordered LaPbMSbO{sub 6} (M=Co, Ni) were synthesized. • Abnormal structural distortion appeared in the ab plane. • Strong magnetic frustration was confirmed via M{sup 2+}–O–O–M{sup 2+} route. • Dielectric measurements presented a large difference between Co and Ni samples. • 3d-electronic structure determines lattice distortion and physical properties.

Numerical simulation of distorted crystal Darwin width

International Nuclear Information System (INIS)

Wang Li; Xu Zhongmin; Wang Naxiu

2012-01-01

A new numerical simulation method according to distorted crystal optical theory was used to predict the direct-cooling crystal monochromator optical properties(crystal Darwin width) in this study. The finite element analysis software was used to calculate the deformed displacements of DCM crystal and to get the local reciprocal lattice vector of distorted crystal. The broadening of direct-cooling crystal Darwin width in meridional direction was estimated at 4.12 μrad. The result agrees well with the experimental data of 5 μrad, while it was 3.89 μrad by traditional calculation method of root mean square (RMS) of the slope error in the center line of footprint. The new method provides important theoretical support for designing and processing of monochromator crystal for synchrotron radiation beamline. (authors)

Correction of distortion of MR pictures for MR-guided robotic sterotactic procedures

International Nuclear Information System (INIS)

Jonckheere, E.A.; Kwoh, Y.S.

1988-01-01

Ever since magnetic resonance (MR) invaded the medical imaging field, it has played an increasingly important role and is even currently being considered for stereotactic guidance of probes in the brain. While MR pictures indeed convey more clinical information than CT, the geometry of MR pictures is, unfortunately, not as accurate as the geometry of CT pictures. In other words, if a square grid phantom is scanned, then the CT picture will show a square grid, while the MR picture will rather reveal a distorted grid. This distortion is primarily due to small variations in the static magnetic field. This small distortion does not impede radiological diagnosis; however, it is a source of concern if one contemplates utilizing the MR pictures for accurate stereotactic positioning of a probe at a very precise point in the brain. Another area of application where the distortion of the MR picture should be compensated for is the superposition of CT and MR pictures so that both informations could be used for diagnosis or stereotactic purposes. This paper essentially addresses the nonlinear distortion of MR pictures and how it could be compensated for through software manipulation of the MR picture

Multipole analysis of redshift-space distortions around cosmic voids

Science.gov (United States)

Hamaus, Nico; Cousinou, Marie-Claude; Pisani, Alice; Aubert, Marie; Escoffier, Stéphanie; Weller, Jochen

2017-07-01

We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about 2 h-1Mpc. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrain the growth rate of structure via the redshift-space distortion parameter β at two median redshifts, β(bar z=0.32)=0.599+0.134-0.124 and β(bar z=0.54)=0.457+0.056-0.054, with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild 2σ deviation at bar z=0.32, which increases to 3σ when the data is restricted to the lowest available redshift range of 0.15

Multipole analysis of redshift-space distortions around cosmic voids

Energy Technology Data Exchange (ETDEWEB)

Hamaus, Nico; Weller, Jochen [Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians Universität, Scheinerstr. 1, D-81679 München (Germany); Cousinou, Marie-Claude; Pisani, Alice; Aubert, Marie; Escoffier, Stéphanie, E-mail: hamaus@usm.lmu.de, E-mail: cousinou@cppm.in2p3.fr, E-mail: pisani@cppm.in2p3.fr, E-mail: maubert@cppm.in2p3.fr, E-mail: escoffier@cppm.in2p3.fr, E-mail: jochen.weller@usm.lmu.de [Aix Marseille Univ., CNRS/IN2P3, CPPM, 163 avenue de Luminy, F-13288, Marseille (France)

2017-07-01

We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about 2 h {sup −1}Mpc. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrain the growth rate of structure via the redshift-space distortion parameter β at two median redshifts, β( z-bar =0.32)=0.599{sup +0.134}{sub −0.124} and β( z-bar =0.54)=0.457{sup +0.056}{sub −0.054}, with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild 2σ deviation at z-bar =0.32, which increases to 3σ when the data is restricted to the lowest available redshift range of 0.15< z <0.33.

Multipole analysis of redshift-space distortions around cosmic voids

International Nuclear Information System (INIS)

Hamaus, Nico; Weller, Jochen; Cousinou, Marie-Claude; Pisani, Alice; Aubert, Marie; Escoffier, Stéphanie

2017-01-01

We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about 2 h −1 Mpc. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrain the growth rate of structure via the redshift-space distortion parameter β at two median redshifts, β( z-bar =0.32)=0.599 +0.134 −0.124 and β( z-bar =0.54)=0.457 +0.056 −0.054 , with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild 2σ deviation at z-bar =0.32, which increases to 3σ when the data is restricted to the lowest available redshift range of 0.15< z <0.33.

SBS [stimulated Brillouin scattering] pulse distortion in multimode optical fibers

International Nuclear Information System (INIS)

Smith, J.R.; Hawkins, R.J.; Laumann, C.W.; Hatch, J.

1989-01-01

We have observed sever temporal-pulse-shape distortion due to stimulated Brillouin scattering (SBS) in multimode optical fibers used to diagnose 351 m laser pulses on the Nova laser system. Our measurements can be fit by a basic model of SBS and provide a clear indication of the intensity and temporal regimes where significant SBS-induced temporal-pulse-shape distortion can be avoided. 15 refs., 3 figs., 1 tab

Pulse Distortion in Saturated Fiber Optical Parametric Chirped Pulse Amplification

DEFF Research Database (Denmark)

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

2012-01-01

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

Analysis of welding distortion due to narrow-gap welding of upper port plug

International Nuclear Information System (INIS)

Biswas, Pankaj; Mandal, N.R.; Vasu, Parameswaran; Padasalag, Shrishail B.

2010-01-01

Narrow-gap welding is a low distortion welding process. This process allows very thick plates to be joined using fewer weld passes as compared to conventional V-groove or double V-groove welding. In case of narrow-gap arc welding as the heat input and weld volume is low, it reduces thermal stress leading to reduction of both residual stress and distortion. In this present study the effect of narrow-gap welding was studied on fabrication of a scaled down port plug in the form of a trapezoidal box made of 10 mm thick mild steel (MS) plates using gas tungsten arc welding (GTAW). Inherent strain method was used for numerical prediction of resulting distortions. The numerical results compared well with that of the experimentally measured distortion. The validated numerical scheme was used for prediction of weld induced distortion due to narrow-gap welding of full scale upper port plug made of 60 mm thick SS316LN material as is proposed for use in ITER project. It was observed that it is feasible to fabricate the said port plug keeping the distortions minimum within about 7 mm using GTAW for root pass welding followed by SMAW for filler runs.

Simulation and experimental study on distortion of butt and T-joints using WELD PLANNER

International Nuclear Information System (INIS)

Sulaiman, Mohd Shahar; Manurung, Yupiter HP; Rahim, Mohammad Ridzwan Abdul Mohd; Redza, Ridhwan; Lidam, Robert Ngendang Ak.; Abas, Sunhaji Kiyai; Tham, Ghalib; Haruman, Esa; Chau, Chan Yin

2011-01-01

This paper investigates the capability of linear thermal elastic numerical analysis to predict the welding distortion that occurs due to GMAW process. Distortion is considered as the major stumbling block that can adversely affect the dimensional accuracy and thus lead to expensive corrective work. Hence, forecast of distortion is crucially needed and ought to be determined in advance in order to minimize the negative effects, improve the quality of welded parts and finally to reduce the production costs. In this study, the welding deformation was simulated by using relatively new FEM software WELD PLANNER developed by ESI Group. This novel Welding Simulation Solution was employed to predict welding distortion induced in butt and T-joints with thickness of 4 mm. Low carbon steel material was used for the simulation and experimental study. A series of experiments using fully automated welding process were conducted for verification purpose to measure the distortion. By comparing between the simulation and experimental results, it was found out that this program code offered fast solution analysis time in estimating weld induced distortion within acceptable accuracy

Simulation and experimental study on distortion of butt and T-joints using WELD PLANNER

Energy Technology Data Exchange (ETDEWEB)

Sulaiman, Mohd Shahar; Manurung, Yupiter HP; Rahim, Mohammad Ridzwan Abdul Mohd; Redza, Ridhwan; Lidam, Robert Ngendang Ak.; Abas, Sunhaji Kiyai; Tham, Ghalib [Universiti Teknologi MARA, Kuala Lumpur (Malaysia); Haruman, Esa [Bakrie University, Jakarta (Indonesia); Chau, Chan Yin [ESI Group, Kuala Lumpur (Malaysia)

2011-10-15

This paper investigates the capability of linear thermal elastic numerical analysis to predict the welding distortion that occurs due to GMAW process. Distortion is considered as the major stumbling block that can adversely affect the dimensional accuracy and thus lead to expensive corrective work. Hence, forecast of distortion is crucially needed and ought to be determined in advance in order to minimize the negative effects, improve the quality of welded parts and finally to reduce the production costs. In this study, the welding deformation was simulated by using relatively new FEM software WELD PLANNER developed by ESI Group. This novel Welding Simulation Solution was employed to predict welding distortion induced in butt and T-joints with thickness of 4 mm. Low carbon steel material was used for the simulation and experimental study. A series of experiments using fully automated welding process were conducted for verification purpose to measure the distortion. By comparing between the simulation and experimental results, it was found out that this program code offered fast solution analysis time in estimating weld induced distortion within acceptable accuracy.

Corrosion behaviour of high temperature alloys in impure helium environments

International Nuclear Information System (INIS)

Shindo, Masami; Quadakkers, W.J.; Schuster, H.

1986-01-01

Corrosion tests with Ni-base high temperature alloys were carried out at 900 and 950 0 C in simulated high temperature reactor helium environments. It is shown that the carburization and decarburization behaviour is strongly affected by the Cr and Ti(Al) contents of the alloys. In carburizing environments, additions of Ti, alone or in combination with Al, significantly improve the carburization resistance. In oxidizing environment, the alloys with high Cr and Al(Ti) contents are the most resistant against decarburization. In this environment alloys with additions of Ti and Al show poor oxidation resistance. The experimental results obtained are compared with a recently developed theory describing corrosion of high temperature alloys in high temperature reactor helium environments. (orig.)

A method to correct coordinate distortion in EBSD maps

DEFF Research Database (Denmark)

Zhang, Yubin; Elbrønd, Andreas Benjamin; Lin, Fengxiang

2014-01-01

Drift during electron backscatter diffraction mapping leads to coordinate distortions in resulting orientation maps, which affects, in some cases significantly, the accuracy of analysis. A method, thin plate spline, is introduced and tested to correct such coordinate distortions in the maps after...... the electron backscatter diffraction measurements. The accuracy of the correction as well as theoretical and practical aspects of using the thin plate spline method is discussed in detail. By comparing with other correction methods, it is shown that the thin plate spline method is most efficient to correct...

Correcting geometric and photometric distortion of document images on a smartphone

Science.gov (United States)

Simon, Christian; Williem; Park, In Kyu

2015-01-01

A set of document image processing algorithms for improving the optical character recognition (OCR) capability of smartphone applications is presented. The scope of the problem covers the geometric and photometric distortion correction of document images. The proposed framework was developed to satisfy industrial requirements. It is implemented on an off-the-shelf smartphone with limited resources in terms of speed and memory. Geometric distortions, i.e., skew and perspective distortion, are corrected by sending horizontal and vertical vanishing points toward infinity in a downsampled image. Photometric distortion includes image degradation from moiré pattern noise and specular highlights. Moiré pattern noise is removed using low-pass filters with different sizes independently applied to the background and text region. The contrast of the text in a specular highlighted area is enhanced by locally enlarging the intensity difference between the background and text while the noise is suppressed. Intensive experiments indicate that the proposed methods show a consistent and robust performance on a smartphone with a runtime of less than 1 s.

Luminosity Loss due to Beam Distortion and the Beam-Beam Instability

CERN Document Server

Wu, Juhao; Raubenheimer, Tor O; Seryi, Andrei; Sramek, Christopher K

2005-01-01

In a linear collider, sources of emittance dilution such as transverse wakefields or dispersive errors will couple the vertical phase space to the longitudinal position within the beam (the so-called ‘banana effect'). When the Intersection Point (IP) disruption parameter is large, these beam distortions will be amplified by a single bunch kink instability which will lead to luminosity loss. We study this phenomena both analytically using linear theory and via numerical simulation. In particular, we examine the dependence of the luminosity loss on the wavelength of the beam distortions and the disruption parameter. This analysis may prove useful when optimizing the vertical disruption parameter for luminosity operation with given beam distortions.

Distortion of Schwarzschild-anti-de Sitter black holes to black strings

International Nuclear Information System (INIS)

Tomimatsu, Akira

2005-01-01

Motivated by the existence of black holes with various topologies in four-dimensional spacetimes with a negative cosmological constant, we study axisymmetric static solutions describing any large distortions of Schwarzschild-anti-de Sitter black holes parametrized by the mass m. Under the approximation such that m is much larger than the anti-de Sitter radius, it is found that a cylindrically symmetric black string is obtained as a special limit of distorted spherical black holes. Such a prolonged distortion of the event horizon connecting a Schwarzschild-anti-de Sitter black hole to a black string is allowed without violating both the usual black hole thermodynamics and the hoop conjecture for the horizon circumference

Study and distortion correction in a selective dissemination of information system

International Nuclear Information System (INIS)

Freitas Queiroz, I.O. de.

1978-03-01

The Selective Dissemination of Information (S D I) system of the Nuclear Information Center (Brazil) was presented, and some parameters, for the evaluation of performance and distortion were defined. These parameters were quantified for a sample of 35 user's profiles and 25.818 documents. Possible distortion factors were analysed, and some were selected, so that they could be automatically processed. The 35 profiles were up-dated by use of two algorithms developed for this purpose. For the up-dated profiles new values of the parameters were determined and showed that distortion decreased and efficiency improved. Critical points of the system were identified and new studies, on topics investigated superficially, were proposed. (Author) [pt

Anomalous Centrifugal Distortion in NH_2

Science.gov (United States)

Martin-Drumel, Marie-Aline; Pirali, Olivier; Coudert, L. H.

2017-06-01

The NH2 radical spectrum, first observed by Herzberg and Ramsay, is dominated by a strong Renner-Teller effect giving rise to two electronic states: the bent X ^{2}B_1 ground state and the quasi-linear A ^{2}A_1 excited state. The NH2 radical has been the subject of numerous high-resolution investigations and its electronic and ro-vibrational transitions have been measured. Using synchrotron radiation, new rotational transitions have been recently recorded and a value of the rotational quantum number N as large as 26 could be reached. In the X ^{2}B_1 ground state, the NH2 radical behaves like a triatomic molecule displaying spin-rotation splittings. Due to the lightness of the molecule, a strong coupling between the overall rotation and the bending mode arises whose effects increase with N and lead to the anomalous centrifugal distortion evidenced in the new measurements.^d In this talk the Bending-Rotation approach developed to account for the anomalous centrifugal distortion of the water molecule is modified to include spin-rotation coupling and applied to the fitting of high-resolution data pertaining to the ground electronic state of NH2. A preliminary line position analysis of the available data^{c,d} allowed us to account for 1681 transitions with a unitless standard deviation of 1.2. New transitions could also be assigned in the spectrum recorded by Martin-Drumel et al.^d In the talk, the results obtained with the new theoretical approach will be compared to those retrieved with a Watson-type Hamiltonian and the effects of the vibronic coupling between the ground X ^{2}B_1 and the excited A ^{2}A_1 electronic state will be discussed. Herzberg and Ramsay, J. Chem. Phys. 20 (1952) 347 Dressler and Ramsay, Phil. Trans. R. Soc. A 25 (1959) 553 Hadj Bachir, Huet, Destombes, and Vervloet, J. Molec. Spectrosc. 193 (1999) 326 McKellar, Vervloet, Burkholder, and Howard, J. Molec. Spectrosc. 142 (1990) 319 Morino and Kawaguchi, J. Molec. Spectrosc. 182 (1997) 428

Gambling-related cognitive distortions predict level of function among US veterans seeking treatment for gambling disorders.

Science.gov (United States)

Shirk, Steven D; Kelly, Megan M; Kraus, Shane W; Potenza, Marc N; Pugh, Kendra; Waltrous, Christopher; Federman, Edward; Krebs, Christopher; Drebing, Charles E

2018-03-01

Gambling Disorder (GD) is characterized by recurrent gambling behavior that is associated with significant impairment and distress, high psychiatric comorbidities, and high functional disability. The military veteran population appears particularly susceptible to developing the disorder, but relatively little has been studied among this population. The purpose of the present study is to investigate the clinical psychopathologies and comorbidities of veterans seeking treatment for problem gambling and how problem gambling may impact functioning. Treatment-seeking veterans meeting criteria for GD (N = 61) underwent a structured clinical interview and completed the South Oaks Gambling Screen (SOGS), the Gambling Symptom Assessment Scale (G-SAS), the Yale-Brown Obsessive-Compulsive Scale for Gambling Disorder (PG-YBOCS), the Gambling Belief Questionnaire (GBQ), the Barratt Impulsiveness Scale (BIS-11), and the Sheehan Disability Scale (SDS). Veterans seeking treatment for GD had high rates of psychiatric and addiction disorder comorbidities. Few veterans had previously sought treatment and most reported substantive challenges in social and occupational functioning. When determining how gambling-related characteristics (ie, severity and cognitive distortions) impact function, severity of cognitive distortions was the strongest statistical predictor of overall functional disability. The findings from this study indicate that there is high comorbidity between GD and other psychiatric and addictive disorders, as well as social and occupational functioning. In addition, cognitive distortions related to gambling relate importantly to overall functioning and should be considered in the development of interventions for veterans with GD. (Am J Addict 2018;27:108-115). © 2018 American Academy of Addiction Psychiatry.

Numerical and semi-analytical modelling of the process induced distortions in pultrusion

DEFF Research Database (Denmark)

Baran, Ismet; Carlone, P.; Hattel, Jesper Henri

2013-01-01

, the transient distortions are inferred adopting a semi-analytical procedure, i.e. post processing numerical results by means of analytical methods. The predictions of the process induced distortion development using the aforementioned methods are found to be qualitatively close to each other...

Optical Method for Detecting Displacements and Strains at Ultra-High Temperatures During Thermo-Mechanical Testing

Science.gov (United States)

Smith, Russell W. (Inventor); Rivers, H. Kevin (Inventor); Sikora, Joseph G. (Inventor); Roth, Mark C. (Inventor); Johnston, William M. (Inventor)

2016-01-01

An ultra-high temperature optical method incorporates speckle optics for sensing displacement and strain measurements well above conventional measurement techniques. High temperature pattern materials are used which can endure experimental high temperature environments while simultaneously having a minimum optical aberration. A purge medium is used to reduce or eliminate optical distortions and to reduce, and/or eliminate oxidation of the target specimen.

Comparison of digital mammography and digital breast tomosynthesis in the detection of architectural distortion.

Science.gov (United States)

Dibble, Elizabeth H; Lourenco, Ana P; Baird, Grayson L; Ward, Robert C; Maynard, A Stanley; Mainiero, Martha B

2018-01-01

To compare interobserver variability (IOV), reader confidence, and sensitivity/specificity in detecting architectural distortion (AD) on digital mammography (DM) versus digital breast tomosynthesis (DBT). This IRB-approved, HIPAA-compliant reader study used a counterbalanced experimental design. We searched radiology reports for AD on screening mammograms from 5 March 2012-27 November 2013. Cases were consensus-reviewed. Controls were selected from demographically matched non-AD examinations. Two radiologists and two fellows blinded to outcomes independently reviewed images from two patient groups in two sessions. Readers recorded presence/absence of AD and confidence level. Agreement and differences in confidence and sensitivity/specificity between DBT versus DM and attendings versus fellows were examined using weighted Kappa and generalised mixed modeling, respectively. There were 59 AD patients and 59 controls for 1,888 observations (59 × 2 (cases and controls) × 2 breasts × 2 imaging techniques × 4 readers). For all readers, agreement improved with DBT versus DM (0.61 vs. 0.37). Confidence was higher with DBT, p = .001. DBT achieved higher sensitivity (.59 vs. .32), p .90). DBT achieved higher positive likelihood ratio values, smaller negative likelihood ratio values, and larger ROC values. DBT decreases IOV, increases confidence, and improves sensitivity while maintaining high specificity in detecting AD. • Digital breast tomosynthesis decreases interobserver variability in the detection of architectural distortion. • Digital breast tomosynthesis increases reader confidence in the detection of architectural distortion. • Digital breast tomosynthesis improves sensitivity in the detection of architectural distortion.

The lattice distortion effect for zinc-blende CrAs and CrSb

International Nuclear Information System (INIS)

Yamana, Keita; Geshi, Masaaki; Tsukamoto, Hidekazu; Uchida, Ichiro; Shirai, Masafumi; Kusakabe, Koichi; Suzuki, Naoshi

2004-01-01

We investigated the stability of the ferromagnetism of CrAs and CrSb in the zinc-blende structure against the lattice distortion, systematically. A calculation within the generalized gradient approximation using a full potential linearized augmented plane wave method was performed. We compared the ferromagnetic state and the antiferromagnetic state assuming tetragonal distortion with the lattice constants a and c changing independently and determined the spin polarization ratio in the ferromagnetic phase. The result shows that complete spin polarization (half-metallic ferromagnetism) remains stable even in the presence of large tetragonal distortion. On the other hand, our calculation shows that two monolayers of CrAs is enough to produce a half-metallic state in the CrAs/GaAs multilayer. Thus, the present result suggests that the half-metallic nature persists in various atomic-scale superlattices made of distorted CrAs or CrSb

Fish's Muscles Distortion and Pectoral Fins Propulsion of Lift-Based Mode

Science.gov (United States)

Yang, S. B.; Han, X. Y.; Qiu, J.

As a sort of MPF(median and/or paired fin propulsion), pectoral fins propulsion makes fish easier to maneuver than other propulsion, according to the well-established classification scheme proposed by Webb in 1984. Pectoral fins propulsion is classified into oscillatory propulsion, undulatory propulsion and compound propulsion. Pectoral fins oscillatory propulsion, is further ascribable to two modes: drag-based mode and lift-based mode. And fish exhibits strong cruise ability by using lift-based mode. Therefore to robot fish design using pectoral fins lift-based mode will bring a new revolution to resources exploration in blue sea. On the basis of the wave plate theory, a kinematic model of fish’s pectoral fins lift-based mode is established associated with the behaviors of cownose ray (Rhinoptera bonasus) in the present work. In view of the power of fish’s locomotion from muscle distortion, it would be helpful benefit to reveal the mechanism of fish’s locomotion variation dependent on muscles distortion. So this study puts forward the pattern of muscles distortion of pectoral fins according to the character of skeletons and muscles of cownose ray in morphology and simulates the kinematics of lift-based mode using nonlinear analysis software. In the symmetrical fluid field, the model is simulated left-right symmetrically or asymmetrically. The results qualitatively show how muscles distortion determines the performance of fish locomotion. Finally the efficient muscles distortion associated with the preliminary dynamics is induced.

Emittance and beam size distortion due to linear coupling

International Nuclear Information System (INIS)

Parzen, G.

1993-01-01

At injection, the presence of linear coupling may result in an increased beam emittance and in increased beam dimensions. Results for the emittance in the presence of linear coupling will be found. These results for the emittance distortion show that the harmonics of the skew quadrupole field close to ν x + ν y are the important harmonics. Results will be found for the important driving terms for the emittance distortion. It will be shown that if these driving terms are corrected, then the total emittance is unchanged, var-epsilon x + var-epsilon y = var-epsilon 1 + var-epsilon 2 . Also, the increase in the beam dimensions will be limited to a factor which is less than 1.414. If the correction is good enough, see below for details, one can achieve var-epsilon 1 = var-epsilon x , var-epsilon 2 = var-epsilon where var-epsilon 1 , var-epsilon 2 are the emittances in the presence of coupling, and the beam dimensions are unchanged. Global correction of the emittance and beam size distortion appears possible

Soft x-ray absorption spectroscopy on Co doped ZnO: structural distortions and electronic structure

International Nuclear Information System (INIS)

Kowalik, I A; Guziewicz, E; Godlewski, M; Arvanitis, D

2016-01-01

We present soft x-ray absorption spectra from a series of Co doped ZnO films. We discuss systematic variations of the Co L-edge white line intensity and multiplet features for this series of samples. We document sizeable differences in the electronic state of the Co ionic cores, as well as in the local environment of the host lattice atoms, characterised by means of x-ray absorption spectra at the O K-edge and Zn L-edges. Model calculations allow to correlate the observed effects to small structural distortions of the ZnO lattice. (paper)

Effects of Field Distortions in IH-APF Linac for a Compact Medical Accelerator

CERN Document Server

Kapin, Valery; Yamada, Satoru

2004-01-01

The project on developing compact medical accelerators for the tumor therapy using carbon ions has been started at the National Institute of Radiological Sciences (NIRS). Alternating-phase-focused (APF) linac using an interdigital H-mode (IH) cavity has been proposed for the injector linac. The IH-cavity is a doubly ridged circular resonator loaded by the drift-tubes mounted on ridges with supporting stems. The effects of intrinsic and random field distortions in a practical design of the 4-Mev/u 200-MHz IH-APF linac are considered. The intrinsic field distortions in the IH-cavity are caused by an asymmetry of the gap fields due to presence of the stems and pair of ridges. The random field distortions are caused by drift-tube misalignments and non-regular deviations of the gap voltages from programmed values. The RF fields in the IH-cavity have been calculated using Microwave Studio (MWS) code. The effects of field distortions on beam dynamics have been simulated numerically. The intrinsic field distortions a...

Vacuum energy density near static distorted black holes

International Nuclear Information System (INIS)

Frolov, V.P.; Sanchez, N.

1986-01-01

We investigate the contribution of massless fields of spins 0, 1/2, and 1 to the vacuum polarization near the event horizon of static Ricci-flat space-times. We do not assume any particular spatial symmetry. Within the Page-Brown ''ansatz'' we calculate 2 >/sup ren/ and /sup ren/ near static distorted black holes, for both the Hartle-Hawking (Vertical Bar>/sub H/) and Boulware (Vertical Bar>/sub B/) vacua. Using Israel's description of static space-times, we express these quantities in an invariant geometric way. We obtain that 2 >/sub H//sup ren/ and /sub H//sup ren/ near the horizon depend only on the two-dimensional geometry of the horizon surface. We find 2 >/sub H//sup ren/ = (1/48π 2 )K 0 , 0 0 >/sub H//sup ren/ = (7α+12β )K 0 2 -α/sup( 2 )ΔK 0 . $K sub 0: is the Gaussian curvature of the horizon, and α and β are numerical coefficients depending on the spin of a field. The term in /sup( 2 )ΔK 0 is characteristic of the distortion of the black hole. When the event horizon is not distorted, K 0 is a constant and this term disappears

High genetic differentiation between an African and a non-African strain of Drosophila simulans revealed by segregation distortion and reduced crossover frequency.

Science.gov (United States)

Tatsuta, Haruki; Takano-Shimizu, Toshiyuki

2009-11-01

Drosophila simulans strains originating from Madagascar and nearby islands in the Indian Ocean often differ from those elsewhere in the number of sex comb teeth and the degree of morphological anomaly in hybrids with D. melanogaster. Here, we report a strong segregation distortion in the F1 intercross between two D. simulans strains originating from Madagascar and the US, possibly at both the gametic and zygotic levels. Strong bias against alleles of the Madagascar strain was observed for all ten marker loci distributed over the entire second chromosome in the F1 intercross, but only a few showed a weak distortion in the isogenic backgrounds of either strains. Significant deviations of genotype frequencies from Hardy-Weinberg proportions were consistently observed for the second chromosome. By contrast, the X and third chromosomes did not show any strong segregation distortion. Crossover frequency on the second chromosome was uniformly reduced in isogenic backgrounds whereas the map lengths in the F1 intercross were comparable to or larger than that of the standard D. melanogaster map. We discuss these findings in relation to previous studies on other traits and interspecific differences between D. mauritiana, which is endemic to Mauritius Island, and D. simulans.

Ubiquitous log odds: a common representation of probability and frequency distortion in perception, action and cognition

Directory of Open Access Journals (Sweden)

Hang eZhang

2012-01-01

Full Text Available In decision from experience, the source of probability information affects how probability is distorted in the decision task. Understanding how and why probability is distorted is a key issue in understanding the peculiar character of experience-based decision. We consider how probability information is used not just in decision making but also in a wide variety of cognitive, perceptual and motor tasks. Very similar patterns of distortion of probability/frequency information have been found in visual frequency estimation, frequency estimation based on memory, signal detection theory, and in the use of probability information in decision-making under risk and uncertainty. We show that distortion of probability in all cases is well captured as linear transformations of the log odds of frequency and/or probability, a model with a slope parameter and an intercept parameter. We then consider how task and experience influence these two parameters and the resulting distortion of probability. We review how the probability distortions change in systematic ways with task and report three experiments on frequency distortion where the distortions change systematically in the same task. We found that the slope of frequency distortions decreases with the sample size, which is echoed by findings in decision from experience. We review previous models of the representation of uncertainty and find that none can account for the empirical findings.

Correlation of lattice distortion with photocatalytic activity of titanium dioxide

International Nuclear Information System (INIS)

Wang Xia; Shui Miao; Li Rongsheng; Song Yue

2008-01-01

The photocatalytic activity of titanium dioxide dispersions on X-3B pigment degradation has been investigated. A variety of factors that would influence the photocatalytic activity such as crystallite size, lattice distortion, and anatase content are discussed in detail. It is found that lattice distortion is the most important one among these factors and is expected to inhibit the hole and electron pair recombination. It determines, to some extent, the photocatalytic efficiency of titanium dioxide dispersions

Numerical convergence in simulations of multiaxial ratcheting with directional distortional hardening

Czech Academy of Sciences Publication Activity Database

Welling, CH.A.; Marek, René; Feigenbaum, H. P.; Dafalias, Y.F.; Plešek, Jiří; Hrubý, Zbyněk; Parma, Slavomír

2017-01-01

Roč. 126, November (2017), s. 105-121 ISSN 0020-7683 R&D Projects: GA MŠk(CZ) EF15_003/0000493; GA MŠk LH14018 Keywords : plastic ity * yield * ratcheting * yield surface distortion * directional distortional hardening Subject RIV: JG - Metallurgy OBOR OECD: Materials engineering Impact factor: 2.760, year: 2016 http://www.sciencedirect.com/science/article/pii/S0020768317303499

Robust Bayes Forecasting For Grouped Binary Data With Known Distortion Interval

OpenAIRE

Pashkevich, M.

2004-01-01

The paper is devoted the problem of robust forecasting for the beta-mixed hierarchical models of grouped binary data in the case of stochastic additive distortions of binary observations. In the case of known lower and upper bounds of the distortion intervals, a new robust minimax Bayes predictor is developed. The performance of the proposed forecasting technique is validated by computer simulationtadata.

Effect of Trailing Intensive Cooling on Residual Stress and Welding Distortion of Friction Stir Welded 2060 Al-Li Alloy

Science.gov (United States)

Ji, Shude; Yang, Zhanpeng; Wen, Quan; Yue, Yumei; Zhang, Liguo

2018-04-01

Trailing intensive cooling with liquid nitrogen has successfully applied to friction stir welding of 2 mm thick 2060 Al-Li alloy. Welding temperature, plastic strain, residual stress and distortion of 2060 Al-Li alloy butt-joint are compared and discussed between conventional cooling and trailing intensive cooling using experimental and numerical simulation methods. The results reveal that trailing intensive cooling is beneficial to shrink high temperature area, reduce peak temperature and decrease plastic strain during friction stir welding process. In addition, the reduction degree of plastic strain outside weld is smaller than that inside weld. Welding distortion presents an anti-saddle shape. Compared with conventional cooling, the reductions of welding distortion and longitudinal residual stresses of welding joint under intense cooling reach 47.7 % and 23.8 %, respectively.

Visualization of Hyperconjugation and Subsequent Structural Distortions through 3D Printing of Crystal Structures.

Science.gov (United States)

Mithila, Farha J; Oyola-Reynoso, Stephanie; Thuo, Martin M; Atkinson, Manza Bj

2016-01-01

Structural distortions due to hyperconjugation in organic molecules, like norbornenes, are well captured through X-ray crystallographic data, but are sometimes difficult to visualize especially for those applying chemical knowledge and are not chemists. Crystal structure from the Cambridge database were downloaded and converted to .stl format. The structures were then printed at the desired scale using a 3D printer. Replicas of the crystal structures were accurately reproduced in scale and any resulting distortions were clearly visible from the macroscale models. Through space interactions or effect of through space hyperconjugation was illustrated through loss of symmetry or distortions thereof. The norbornene structures exhibits distortion that cannot be observed through conventional ball and stick modelling kits. We show that 3D printed models derived from crystallographic data capture even subtle distortions in molecules. We translate such crystallographic data into scaled-up models through 3D printing.

Bending Distortion Analysis of a Steel Shaft Manufacturing Chain from Cold Drawing to Grinding

Science.gov (United States)

Dias, Vinicius Waechter; da Silva Rocha, Alexandre; Zottis, Juliana; Dong, Juan; Epp, Jérémy; Zoch, Hans Werner

2017-04-01

Shafts are usually manufactured from bars that are cold drawn, cut machined, induction hardened, straightened, and finally ground. The main distortion is characterized by bending that appears after induction hardening and is corrected by straightening and/or grinding. In this work, the consequence of the variation of manufacturing parameters on the distortion was analyzed for a complete manufacturing route for production of induction hardened shafts made of Grade 1045 steel. A DoE plan was implemented varying the drawing angle, cutting method, induction hardening layer depth, and grinding penetration depth. The distortion was determined by calculating curvature vectors from dimensional analysis by 3D coordinate measurements. Optical microscopy, microhardness testing, residual stress analysis, and FEM process simulation were used to evaluate and understand effects of the main carriers of distortion potential. The drawing process was identified as the most significant influence on the final distortion of the shafts.

Temperature and distortion transients in gas tungsten-arc weldments

International Nuclear Information System (INIS)

Glickstein, S.S.; Friedman, E.

1979-10-01

An analysis and test program to develop a fundamental understanding of the gas tungsten-arc welding process has been undertaken at the Bettis Atomic Power Laboratory to develop techniques to determine and control the various welding parameters and weldment conditions so as to result in optimum weld response characteristics. These response characteristics include depth of penetration, weld bead configuration, weld bead sink and roll, distortion, and cracking sensitivity. The results are documented of that part of the program devoted to analytical and experimental investigations of temperatures, weld bead dimensions, and distortions for moving gas tungsten-arc welds applied to Alloy 600 plates

Coil extensions improve line shapes by removing field distortions

Science.gov (United States)

Conradi, Mark S.; Altobelli, Stephen A.; McDowell, Andrew F.

2018-06-01

The static magnetic susceptibility of the rf coil can substantially distort the field B0 and be a dominant source of line broadening. A scaling argument shows that this may be a particular problem in microcoil NMR. We propose coil extensions to reduce the distortion. The actual rf coil is extended to a much longer overall length by abutted coil segments that do not carry rf current. The result is a long and nearly uniform sheath of copper wire, in terms of the static susceptibility. The line shape improvement is demonstrated at 43.9 MHz and in simulation calculations.

Distortion product otoacoustic emissions: comparison of sequential vs. simultaneous presentation of primary tones.

Science.gov (United States)

Kumar, U Ajith; Maruthy, Sandeep; Chandrakant, Vishwakarma

2009-03-01

Distortion product otoacoustic emissions are one form of evoked otoacoustic emissions. DPOAEs provide the frequency specific information about the hearing status in mid and high frequency regions. But in most screening protocols TEOAEs are preferred as it requires less time compared to DPOAE. This is because, in DPOAE each stimulus is presented one after the other and responses are analyzed. Grason and Stadler Incorporation 60 (GSI-60) offer simultaneous presentation of four sets of primary tones at a time and checks for the DPOAE. In this mode of presentation, all the pairs are presented at a time and following that response is extracted separately whereas, in sequential mode primaries are presented in orderly fashion one after the other. In this article simultaneous and sequential protocols were used to compare the Distortion product otoacoustic emission amplitude, noise floor and administration time in individuals with normal hearing and mild sensori-neural (SN) hearing loss. In simultaneous protocols four sets of primary tones (i.e. 8 tones) were presented together whereas, in sequential presentation mode one set of primary tones was presented each time. Simultaneous protocol was completed in less than half the time required for the completion of sequential protocol. Two techniques yielded similar results at frequencies above 1000 Hz only in normal hearing group. In SN hearing loss group simultaneous presentation yielded signifi cantly higher noise floors and distortion product amplitudes. This result challenges the use of simultaneous presentation technique in neonatal hearing screening programmes and on other pathologies. This discrepancy between two protocols may be due to some changes in biomechanical process in the cochlear and/or due to higher distortion/noise produced by the system during the simultaneous presentation mode.

Estimates of Atmospheric Distortion Number for Nonlinear Refraction

National Research Council Canada - National Science Library

Roadcap, J. R; McNicholl, P. J; Beland, R. R; Jumper, G. Y

2007-01-01

A characteristic nondimensional distortion number Nd was derived in the 1970s that allows inference of the degree of nonlinear refraction or thermal blooming associated with an atmospheric laser path...

Optimization of a novel large field of view distortion phantom for MR-only treatment planning.

Science.gov (United States)

Price, Ryan G; Knight, Robert A; Hwang, Ken-Pin; Bayram, Ersin; Nejad-Davarani, Siamak P; Glide-Hurst, Carri K

2017-07-01

MR-only treatment planning requires images of high geometric fidelity, particularly for large fields of view (FOV). However, the availability of large FOV distortion phantoms with analysis software is currently limited. This work sought to optimize a modular distortion phantom to accommodate multiple bore configurations and implement distortion characterization in a widely implementable solution. To determine candidate materials, 1.0 T MR and CT images were acquired of twelve urethane foam samples of various densities and strengths. Samples were precision-machined to accommodate 6 mm diameter paintballs used as landmarks. Final material candidates were selected by balancing strength, machinability, weight, and cost. Bore sizes and minimum aperture width resulting from couch position were tabulated from the literature (14 systems, 5 vendors). Bore geometry and couch position were simulated using MATLAB to generate machine-specific models to optimize the phantom build. Previously developed software for distortion characterization was modified for several magnet geometries (1.0 T, 1.5 T, 3.0 T), compared against previously published 1.0 T results, and integrated into the 3D Slicer application platform. All foam samples provided sufficient MR image contrast with paintball landmarks. Urethane foam (compressive strength ∼1000 psi, density ~20 lb/ft 3 ) was selected for its accurate machinability and weight characteristics. For smaller bores, a phantom version with the following parameters was used: 15 foam plates, 55 × 55 × 37.5 cm 3 (L×W×H), 5,082 landmarks, and weight ~30 kg. To accommodate > 70 cm wide bores, an extended build used 20 plates spanning 55 × 55 × 50 cm 3 with 7,497 landmarks and weight ~44 kg. Distortion characterization software was implemented as an external module into 3D Slicer's plugin framework and results agreed with the literature. The design and implementation of a modular, extendable distortion phantom was optimized for several bore

Large crystal structure distortion in DyB6 studied by X-ray diffraction

International Nuclear Information System (INIS)

Granovsky, S.A.; Markosyan, A.S.

2003-01-01

A large magnetoelastic coupling induces a lattice distortion of a rhombohedral type in DyB 6 . Below the quadrupolar ordering temperature T Q =31 K the cubic and the distorted phases coexist. The cubic phase disappears at 23 K, which was identified as the magnetic ordering point T N . In the magnetic phase the distortion (dl/l) 111 increases monotonically with decreasing temperature and reaches the value of 9x10 -3 at 8 K, which is one of the largest value known for cubic compounds

Nonlinear distortion in wireless systems modeling and simulation with Matlab

CERN Document Server

Gharaibeh, Khaled M

2011-01-01

This book covers the principles of modeling and simulation of nonlinear distortion in wireless communication systems with MATLAB simulations and techniques In this book, the author describes the principles of modeling and simulation of nonlinear distortion in single and multichannel wireless communication systems using both deterministic and stochastic signals. Models and simulation methods of nonlinear amplifiers explain in detail how to analyze and evaluate the performance of data communication links under nonlinear amplification. The book addresses the analysis of nonlinear systems

Neural basis of distorted self-face recognition in social anxiety disorder

Directory of Open Access Journals (Sweden)

Min-Kyeong Kim

2016-01-01

Conclusion: Patients with SAD have a positive point of view of their own face and experience self-relevance for the attractively transformed self-faces. This distorted cognition may be based on dysfunctions in the frontal and inferior parietal regions. The abnormal engagement of the fronto-parietal attentional network during processing face stimuli in non-social situations may be linked to distorted self-recognition in SAD.

The relationship between tinnitus pitch and parameters of audiometry and distortion product otoacoustic emissions.

Science.gov (United States)

Keppler, H; Degeest, S; Dhooge, I

2017-11-01

Chronic tinnitus is associated with reduced auditory input, which results in changes in the central auditory system. This study aimed to examine the relationship between tinnitus pitch and parameters of audiometry and distortion product otoacoustic emissions. For audiometry, the parameters represented the edge frequency of hearing loss, the frequency of maximum hearing loss and the frequency range of hearing loss. For distortion product otoacoustic emissions, the parameters were the frequency of lowest distortion product otoacoustic emission amplitudes and the frequency range of reduced distortion product otoacoustic emissions. Sixty-seven patients (45 males, 22 females) with subjective chronic tinnitus, aged 18 to 73 years, were included. No correlation was found between tinnitus pitch and parameters of audiometry and distortion product otoacoustic emissions. However, tinnitus pitch fell mostly within the frequency range of hearing loss. The current study seems to confirm the relationship between tinnitus pitch and the frequency range of hearing loss, thus supporting the homeostatic plasticity model.

Detection threshold for sound distortion resulting from noise reduction in normal-hearing and hearing-impaired listeners.

Science.gov (United States)

Brons, Inge; Dreschler, Wouter A; Houben, Rolph

2014-09-01

Hearing-aid noise reduction should reduce background noise, but not disturb the target speech. This objective is difficult because noise reduction suffers from a trade-off between the amount of noise removed and signal distortion. It is unknown if this important trade-off differs between normal-hearing (NH) and hearing-impaired (HI) listeners. This study separated the negative effect of noise reduction (distortion) from the positive effect (reduction of noise) to allow the measurement of the detection threshold for noise-reduction (NR) distortion. Twelve NH subjects and 12 subjects with mild to moderate sensorineural hearing loss participated in this study. The detection thresholds for distortion were determined using an adaptive procedure with a three-interval, two-alternative forced-choice paradigm. Different levels of distortion were obtained by changing the maximum amount of noise reduction. Participants were also asked to indicate their preferred NR strength. The detection threshold for overall distortion was higher for HI subjects than for NH subjects, suggesting that stronger noise reduction can be applied for HI listeners without affecting the perceived sound quality. However, the preferred NR strength of HI listeners was closer to their individual detection threshold for distortion than in NH listeners. This implies that HI listeners tolerate fewer audible distortions than NH listeners.

Distorted Pattern Recognition and Analysis with the Help of IEf Graph Representation

Directory of Open Access Journals (Sweden)

Adam Sedziwy

2002-01-01

Full Text Available An algorithm for distorted pattern recognition is presented. lt's generalization of M Flasinski results (Pattern Recognition, 27, 1-16, 1992. A new formalism allows to make both qualitative and quantitive distortion analysis. It also enlarges parser flexibility by extending the set of patterns which may be recognized.

Investigation of support vector machine for the detection of architectural distortion in mammographic images

International Nuclear Information System (INIS)

Guo, Q; Shao, J; Ruiz, V

2005-01-01

This paper investigates detection of architectural distortion in mammographic images using support vector machine. Hausdorff dimension is used to characterise the texture feature of mammographic images. Support vector machine, a learning machine based on statistical learning theory, is trained through supervised learning to detect architectural distortion. Compared to the Radial Basis Function neural networks, SVM produced more accurate classification results in distinguishing architectural distortion abnormality from normal breast parenchyma

Investigation of support vector machine for the detection of architectural distortion in mammographic images

Energy Technology Data Exchange (ETDEWEB)

Guo, Q [Department of Cybernetics, University of Reading, Reading RG6 6AY (United Kingdom); Shao, J [Department of Electronics, University of Kent at Canterbury, Kent CT2 7NT (United Kingdom); Ruiz, V [Department of Cybernetics, University of Reading, Reading RG6 6AY (United Kingdom)

2005-01-01

This paper investigates detection of architectural distortion in mammographic images using support vector machine. Hausdorff dimension is used to characterise the texture feature of mammographic images. Support vector machine, a learning machine based on statistical learning theory, is trained through supervised learning to detect architectural distortion. Compared to the Radial Basis Function neural networks, SVM produced more accurate classification results in distinguishing architectural distortion abnormality from normal breast parenchyma.

Probable mode prediction for H.264 advanced video coding P slices using removable SKIP mode distortion estimation

Science.gov (United States)

You, Jongmin; Jeong, Jechang

2010-02-01

The H.264/AVC (advanced video coding) is used in a wide variety of applications including digital broadcasting and mobile applications, because of its high compression efficiency. The variable block mode scheme in H.264/AVC contributes much to its high compression efficiency but causes a selection problem. In general, rate-distortion optimization (RDO) is the optimal mode selection strategy, but it is computationally intensive. For this reason, the H.264/AVC encoder requires a fast mode selection algorithm for use in applications that require low-power and real-time processing. A probable mode prediction algorithm for the H.264/AVC encoder is proposed. To reduce the computational complexity of RDO, the proposed method selects probable modes among all allowed block modes using removable SKIP mode distortion estimation. Removable SKIP mode distortion is used to estimate whether or not a further divided block mode is appropriate for a macroblock. It is calculated using a no-motion reference block with a few computations. Then the proposed method reduces complexity by performing the RDO process only for probable modes. Experimental results show that the proposed algorithm can reduce encoding time by an average of 55.22% without significant visual quality degradation and increased bit rate.

Effect of quantum well position on the distortion characteristics of transistor laser

Science.gov (United States)

Piramasubramanian, S.; Ganesh Madhan, M.; Radha, V.; Shajithaparveen, S. M. S.; Nivetha, G.

2018-05-01

The effect of quantum well position on the modulation and distortion characteristics of a 1300 nm transistor laser is analyzed in this paper. Standard three level rate equations are numerically solved to study this characteristics. Modulation depth, second order harmonic and third order intermodulation distortion of the transistor laser are evaluated for different quantum well positions for a 900 MHz RF signal modulation. From the DC analysis, it is observed that optical power is maximum, when the quantum well is positioned near base-emitter interface. The threshold current of the device is found to increase with increasing the distance between the quantum well and the base-emitter junction. A maximum modulation depth of 0.81 is predicted, when the quantum well is placed at 10 nm from the base-emitter junction, under RF modulation. The magnitude of harmonic and intermodulation distortion are found to decrease with increasing current and with an increase in quantum well distance from the emitter base junction. A minimum second harmonic distortion magnitude of -25.96 dBc is predicted for quantum well position (230 nm) near to the base-collector interface for 900 MHz modulation frequency at a bias current of 20 Ibth. Similarly, a minimum third order intermodulation distortion of -38.2 dBc is obtained for the same position and similar biasing conditions.

Target continuum distorted-wave theory for collisions of fast protons with atomic hydrogen

International Nuclear Information System (INIS)

Crothers, D.S.F.; Dunseath, K.M.

1990-01-01

By considering the target continuum distorted-wave (TCDW) theory as the high-energy limit of the half-way house variational continuum distorted-wave theory, it is shown not only that there is no intermediate elastic divergence but also that the second-order amplitude based on a purely elastic intermediate state is of order υ -6 and is thus negligible. The residual inelastic TCDW theory is developed to second-order at high velocities. It is used to describe charge exchange during collisions of fast protons with atomic hydrogen. Using an on-shell peaking approximation and considering 1s-1s capture it is shown that the residual purely second-order transition amplitude comprises two terms, one real term of order υ -6 and one purely imaginary term of order υ -7 ln υ. At 5 MeV laboratory energy, it is shown that these are negligible. It is also shown that the υ -5 first-order term gives a differential cross section in very good agreement with an experiment at all angles including forward, interference minimum, Thomas maximum and large angles, particularly having folded our theory over experimental resolution. (author)

Experimental Investigation of a Forward Swept Rotor in a Multistage Fan with Inlet Distortion

Directory of Open Access Journals (Sweden)

Aspi R. Wadia

2011-01-01

Full Text Available Previous studies of transonic swept rotors in single stage fans have demonstrated the potential of significant improvements in both efficiency and stall margin with forward swept blading. This paper extends the assessment of the payoff derived from forward sweep to multistage configurations. The experimental investigation compare two builds of an advanced two-stage fan configuration tested alternately with a radial and a forward swept stage 1 blade. In the two-stage evaluations, the testing was extended to include the effect on inlet flow distortion. While the common second stage among the two builds prevented the overall fan from showing clean inlet performance and stability benefits with the forward swept rotor 1, this configuration did demonstrate superior front stage efficiency and tolerance to inlet distortion. Having obtained already low distortion sensitivity with the radial rotor 1 configuration relative to current production military fan standards, the sensitivity to inlet distortion was halved with the forward swept rotor 1 configuration. In the case of the 180-degree one-per-rev distortion pattern, the two-stage configuration was evaluated both with and without inlet guide vanes (IGVs. The presence of the inlet guide vanes had a profound impact in lowering the two-stage fan's sensitivity with inlet distortion.

Reduction of the Jahn-Teller distortion at the insulator-to-metal transition in mixed valence manganites

International Nuclear Information System (INIS)

Garcia-Munoz, J.L.; Suaaidi, M.; Fontcuberta, J.; Rodriguez-Carvajal, J.

1997-01-01

The insulator-to-metal transition in the manganite La 0.52 Y 0.15 Ca 0.33 MnO 3 (T IM ∼115 K) has been studied by high-resolution neutron powder diffraction. The cell volume contraction at the Curie point is accompanied by a remarkable decrease of the Jahn-Teller distortion in MnO 6 octahedra. The change of the Mn-O bond lengths at T IM is anisotropic and brings about a drop out of the basal-plane collective distortion mode Q 2 , proposed to be the deformation responsible for the band split of e g↑ orbitals. This is consistent with the double-exchange picture, and precludes simple ferromagnetic exchange. copyright 1997 The American Physical Society

The possible distortion of autoradiographic results

International Nuclear Information System (INIS)

Kozlov, A.A.; Tumanushvili, G.D.

1980-01-01

The effect of radioactive labelling (H 3 -thymidine) on the infusorian division is studied. The presented results show that introduction of labelled compounds results in accelerating infusorian cell division v. Thorough inestigation of labelled compound effect with low activity on the parameters of cell division and the search of methods to eliminate distortions able to appear in autoradiographic experiments is expedient [ru

Information theory and rate distortion theory for communications and compression

CERN Document Server

Gibson, Jerry

2013-01-01

This book is very specifically targeted to problems in communications and compression by providing the fundamental principles and results in information theory and rate distortion theory for these applications and presenting methods that have proved and will prove useful in analyzing and designing real systems. The chapters contain treatments of entropy, mutual information, lossless source coding, channel capacity, and rate distortion theory; however, it is the selection, ordering, and presentation of the topics within these broad categories that is unique to this concise book. While the cover

Damage to insula abolishes cognitive distortions during simulated gambling.

Science.gov (United States)

Clark, Luke; Studer, Bettina; Bruss, Joel; Tranel, Daniel; Bechara, Antoine

2014-04-22

Gambling is a naturalistic example of risky decision-making. During gambling, players typically display an array of cognitive biases that create a distorted expectancy of winning. This study investigated brain regions underpinning gambling-related cognitive distortions, contrasting patients with focal brain lesions to the ventromedial prefrontal cortex (vmPFC), insula, or amygdala ("target patients") against healthy comparison participants and lesion comparison patients (i.e., with lesions that spare the target regions). A slot machine task was used to deliver near-miss outcomes (i.e., nonwins that fall spatially close to a jackpot), and a roulette game was used to examine the gambler's fallacy (color decisions following outcome runs). Comparison groups displayed a heightened motivation to play following near misses (compared with full misses), and manifested a classic gambler's fallacy effect. Both effects were also observed in patients with vmPFC and amygdala damage, but were absent in patients with insula damage. Our findings indicate that the distorted cognitive processing of near-miss outcomes and event sequences may be ordinarily supported by the recruitment of the insula. Interventions to reduce insula reactivity could show promise in the treatment of disordered gambling.

Optical conoscopy of distorted uniaxial liquid crystals: computer simulation and experiment

OpenAIRE

Yu.A.Nastishin; O.B.Dovgyi; O.G.Vlokh

2001-01-01

We propose an algorithm to compute the conoscopic pattern for distorted uniaxial liquid crystal cells. The computed conoscopic figures for several cells (homeotropic, planar, twist, hybrid, hybrid under an external field) are compared to the corresponding experimental conoscopic patterns. We demonstrate that conoscopy can be used for the characterization of the distorted nematic cells with the director deformations which can not be detected and unambigously characterized by direct microscopy ...

The Relationship Between Religious Orientation, and Gender With a Cognitive Distortion

OpenAIRE

Amirsardari, Leili; Azari, Shafie; Esmali Kooraneh, Ahmad

2014-01-01

Objective: The objective of this study was to determine the relationship between religious orientation (intrinsic?external) and cognitive distortions. Methods: General design of this study considered as a descriptive and correlational method. Universal population in this research consist all students of the Urmia Azad University, which were studying during 2012 and 2013 (n = 250). All respondents filled the Alports religious and cognitive distortions questionnaires. The answers were analyzed ...

Investigation of the 4D composite MR image distortion field associated with tumor motion for MR-guided radiotherapy.

Science.gov (United States)

Stanescu, T; Jaffray, D

2016-03-01

perturbations as it moves further away from the MR isocenter. For a mobile lung tumor, the 4D composite field, corresponding to a 1.5 T field and a readout gradient of 5 mT/m, amounts to 3.0 and 2.8 mm for the MRIgRT system designs featuring B0 oriented along the z-axis (cylindrical-bore scanner) and in the (x,y)-plane (biplanar scanner), respectively. For a rotating biplanar scanner, the composite distortion field varied nonlinearly with the rotation angle. Overall, the dominant contribution to the composite field was from the system-related distortion field. The tumor centroid experienced a systematic shift of 2 mm and showed a negligible perturbation for different B0 values. The dependency on the tumor size was also investigated, namely the max values varied from 1.2 to 2.5 mm for spherical volumes with a diameter between 4 and 80 mm. The composite distortion field requires adequate quantification for lung radiation therapy applications such as treatment planning, pretreatment patient setup verification, and real-time treatment delivery guidance. For certain scenarios such as small tumor volumes, the spatial distortions may be corrected by applying systematic shifts derived from a single tumor motion phase. In the case of high readout gradients common to fast imaging applications, the χ distortions were found to be less than 1 mm irrespective of scanner configuration.

Studies of radial distortions of the ATLAS Inner Detector

CERN Document Server

The ATLAS collaboration

2018-01-01

The measurement of the absolute momentum scale of charged particles provided by the ATLAS inner detector is affected by biases related to geometrical deformations which are not well constrained by the track-based alignment procedure. The focus of this note is on momentum biases related to radial distortions of the inner detector. The $J/\\psi$, $\\Upsilon$, and $Z$-boson resonances decaying into pairs of muons are used to study and quantify such radial distortions in the barrel region of the inner detector. The analysis is performed on data collected in 2016 during Run 2 of the Large Hadron Collider, and corresponding to 33 fb$^{-1}$ of integrated luminosity.

Probing correlations of early magnetic fields using mu-distortion

DEFF Research Database (Denmark)

Ganc, Jonathan; Sloth, Martin Snoager

2014-01-01

the perturbations which produce the $\\mu$-distortion will be much smaller scale than the relevant density perturbations, the observation of this correlation is sensitive to the squeezed limit of $\\langle B^2\\zeta\\rangle$, which is naturally parameterized by $b_{\\text{NL}}$ (a parameter defined analogously to $f_{\\text......{NL}}$). We find that a PIXIE-like CMB experiments has a signal to noise $S/N\\approx 1.0 \\times b_{\\text{NL}} (\\tilde B_\\mu/10\\text{ nG})^2$, where $\\tilde B_\\mu$ is the magnetic field's strength on $\\mu$-distortion scales normalized to today's redshift; thus, a 10 nG field would be detectable with $b_{\\text...

Improved distorted wave theory with the localized virial conditions

Science.gov (United States)

Hahn, Y. K.; Zerrad, E.

2009-12-01

The distorted wave theory is operationally improved to treat the full collision amplitude, such that the corrections to the distorted wave Born amplitude can be systematically calculated. The localized virial conditions provide the tools necessary to test the quality of successive approximations at each stage and to optimize the solution. The details of the theoretical procedure are explained in concrete terms using a collisional ionization model and variational trial functions. For the first time, adjustable parameters associated with an approximate scattering solution can be fully determined by the theory. A small number of linear parameters are introduced to examine the convergence property and the effectiveness of the new approach.

Weld distortion prediction of the ITER Vacuum Vessel using Finite Element simulations

Energy Technology Data Exchange (ETDEWEB)

Caixas, Joan, E-mail: joan.caixas@f4e.europa.eu [F4E, c/ Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Guirao, Julio [Numerical Analysis Technologies, S. L., Marqués de San Esteban 52, Entlo, 33209 Gijon (Spain); Bayon, Angel; Jones, Lawrence; Arbogast, Jean François [F4E, c/ Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Barbensi, Andrea [Ansaldo Nucleare, Corso F.M. Perrone, 25, I-16152 Genoa (Italy); Dans, Andres [F4E, c/ Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Facca, Aldo [Mangiarotti, Pannellia di Sedegliano, I-33039 Sedegliano (UD) (Italy); Fernandez, Elena; Fernández, José [F4E, c/ Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Iglesias, Silvia [Numerical Analysis Technologies, S. L., Marqués de San Esteban 52, Entlo, 33209 Gijon (Spain); Jimenez, Marc; Jucker, Philippe; Micó, Gonzalo [F4E, c/ Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Ordieres, Javier [Numerical Analysis Technologies, S. L., Marqués de San Esteban 52, Entlo, 33209 Gijon (Spain); Pacheco, Jose Miguel [F4E, c/ Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Paoletti, Roberto [Walter Tosto, Via Erasmo Piaggio, 72, I-66100 Chieti Scalo (Italy); Sanguinetti, Gian Paolo [Ansaldo Nucleare, Corso F.M. Perrone, 25, I-16152 Genoa (Italy); Stamos, Vassilis [F4E, c/ Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Tacconelli, Massimiliano [Walter Tosto, Via Erasmo Piaggio, 72, I-66100 Chieti Scalo (Italy)

2013-10-15

Highlights: ► Computational simulations of the weld processes can rapidly assess different sequences. ► Prediction of welding distortion to optimize the manufacturing sequence. ► Accurate shape prediction after each manufacture phase allows to generate modified procedures and pre-compensate distortions. ► The simulation methodology is improved using condensed computation techniques with ANSYS in order to reduce computation resources. ► For each welding process, the models are calibrated with the results of coupons and mock-ups. -- Abstract: The as-welded surfaces of the ITER Vacuum Vessel sectors need to be within a very tight tolerance, without a full-scale prototype. In order to predict welding distortion and optimize the manufacturing sequence, the industrial contract includes extensive computational simulations of the weld processes which can rapidly assess different sequences. The accurate shape prediction, after each manufacturing phase, enables actual distortions to be compared with the welding simulations to generate modified procedures and pre-compensate distortions. While previous mock-ups used heavy welded-on jigs to try to restrain the distortions, this method allows the use of lightweight jigs and yields important cost and rework savings. In order to enable the optimization of different alternative welding sequences, the simulation methodology is improved using condensed computation techniques with ANSYS in order to reduce computational resources. For each welding process, the models are calibrated with the results of coupons and mock-ups. The calibration is used to construct representative models of each segment and sector. This paper describes the application to the construction of the Vacuum Vessel sector of the enhanced simulation methodology with condensed Finite Element computation techniques and results of the calibration on several test pieces for different types of welds.

Weld distortion prediction of the ITER Vacuum Vessel using Finite Element simulations

International Nuclear Information System (INIS)

Caixas, Joan; Guirao, Julio; Bayon, Angel; Jones, Lawrence; Arbogast, Jean François; Barbensi, Andrea; Dans, Andres; Facca, Aldo; Fernandez, Elena; Fernández, José; Iglesias, Silvia; Jimenez, Marc; Jucker, Philippe; Micó, Gonzalo; Ordieres, Javier; Pacheco, Jose Miguel; Paoletti, Roberto; Sanguinetti, Gian Paolo; Stamos, Vassilis; Tacconelli, Massimiliano

2013-01-01

Highlights: ► Computational simulations of the weld processes can rapidly assess different sequences. ► Prediction of welding distortion to optimize the manufacturing sequence. ► Accurate shape prediction after each manufacture phase allows to generate modified procedures and pre-compensate distortions. ► The simulation methodology is improved using condensed computation techniques with ANSYS in order to reduce computation resources. ► For each welding process, the models are calibrated with the results of coupons and mock-ups. -- Abstract: The as-welded surfaces of the ITER Vacuum Vessel sectors need to be within a very tight tolerance, without a full-scale prototype. In order to predict welding distortion and optimize the manufacturing sequence, the industrial contract includes extensive computational simulations of the weld processes which can rapidly assess different sequences. The accurate shape prediction, after each manufacturing phase, enables actual distortions to be compared with the welding simulations to generate modified procedures and pre-compensate distortions. While previous mock-ups used heavy welded-on jigs to try to restrain the distortions, this method allows the use of lightweight jigs and yields important cost and rework savings. In order to enable the optimization of different alternative welding sequences, the simulation methodology is improved using condensed computation techniques with ANSYS in order to reduce computational resources. For each welding process, the models are calibrated with the results of coupons and mock-ups. The calibration is used to construct representative models of each segment and sector. This paper describes the application to the construction of the Vacuum Vessel sector of the enhanced simulation methodology with condensed Finite Element computation techniques and results of the calibration on several test pieces for different types of welds

Total reduction of distorted echelle spectrograms - An automatic procedure. [for computer controlled microdensitometer

Science.gov (United States)

Peterson, R. C.; Title, A. M.

1975-01-01

A total reduction procedure, notable for its use of a computer-controlled microdensitometer for semi-automatically tracing curved spectra, is applied to distorted high-dispersion echelle spectra recorded by an image tube. Microdensitometer specifications are presented and the FORTRAN, TRACEN and SPOTS programs are outlined. The intensity spectrum of the photographic or electrographic plate is plotted on a graphic display. The time requirements are discussed in detail.

Finite element study of growth stress formation in wood and related distortion of sawn timber

DEFF Research Database (Denmark)

Ormarsson, Sigurdur; Dahlblom, O.; Johansson, M.

2009-01-01

-related stresses in wood (drying distortions) and growth-related stresses (distortions appearing when logs are split up to timber boards by sawing). To get more knowledge on how these distortions can be reduced in wooden products, there is a need for improved understanding of this material behaviour through good...... numerical tools developed from empirical data. A three-dimensional finite element board distortion model developed by Ormarsson (1999) has been extended to include the influence of growth stresses by incorporating a one-dimensional finite element growth stress model developed here. The growth stress model...... is formulated as an axisymmetric general plane strain model where material for all new annual rings is progressively added to the tree during the analysis. The simulation results presented include how stresses are progressively generated during the tree growth, distortions related to the redistribution...

Modeling distortion of HIT by an Actuator Disk in a periodic domain

Science.gov (United States)

Ghate, Aditya; Ghaisas, Niranjan; Lele, Sanjiva

2017-11-01

We study the distortion of incompressible, homogeneous isotropic turbulence (HIT) by a dragging actuator disk with a fixed thrust coefficient (under the large Reynolds number limit), using Large Eddy Simulation (LES). The HIT inflow is tailored to ensure that the largest length scales in the flow are smaller than the actuator disk diameter in order to minimize the meandering of the turbulent wake and isolate the length scales that undergo distortion. The numerical scheme (Fourier collocation with dealiasing) and the SGS closure (anisotropic minimum dissipation model) are carefully selected to minimize numerical artifacts expected due to the inviscid assumption. The LES is used to characterize the following 3 properties of the flow a) distortion of HIT due to the expanding streamtube resulting in strong anisotropy, b) turbulent pressure modulation across the actuator disk, and the c) turbulent wake state. Finally, we attempt to model the initial distortion and the pressure modulation using a WKB variant of RDT solved numerically using a set of discrete Gabor modes. Funding provided by Precourt Institute for Energy at Stanford University.

Assessing the sensitivity of information distortion to four potential influences in studies of risky choice

Directory of Open Access Journals (Sweden)

Seth A. Miller

2013-11-01

Full Text Available The emergence of a leading alternative during the course of a decision is known to bias the evaluation of new information in a manner that favors that alternative. We report 3 studies that address the sensitivity of predecisional information distortion and its effects in hypothetical risky decisions with regard to 4 potential influences: choice domain, repeated choice, memory requirements, and intermediate progress questions. In Experiment 1 (N = 515, the magnitude of information distortion was similar in 5 choice domains (varied between participants involving monetary gambles, song downloads, frequent-flyer miles, political decisions, or medical decisions. Information distortion mediated the relationship between our manipulation of initial preferences and participants' final choices, with the magnitude of the indirect effect being roughly similar across domains. These results replicate and extend previous findings. Additionally, distortion decreased significantly over 4 similar decision problems (within participants, but remained significant in the fourth problem. In Experiment 2 (N = 214, information distortion increased significantly when previously viewed information remained available, apparently because reiterating that information strengthened emerging preferences. In Experiment 3 (N = 223, the removal of intermediate progress questions that measure information distortion and emerging preferences did not significantly affect final choices, again replicating previous results. We conclude that predecisional information distortion is a relatively stable and robust phenomenon that deserves a prominent role in descriptive theories of choice.

Detailed dynamic model for semiconductor optical amplifiers and their crosstalk and intermodulation distortion

DEFF Research Database (Denmark)

Durhuus, Terji; Mikkelsen, Benny; Stubkjær, Kristian

1992-01-01

. The model is used to assess intermodulation distortion and crosstalk. Cascaded amplifiers are considered, and the crosstalk and intermodulation distortion due to cascaded amplifiers are found to accumulate by adding together in amplitude; this may limit the number or cascaded amplifiers in multichannel...

The role of appraisal distortion, contempt, and morality in couple conflict: a grounded theory.

Science.gov (United States)

Whiting, Jason B

2008-01-01

A common goal of couples' therapy is to help individuals modify their view of each other and the relationship. Distorted views and appraisals contribute to conflict, and these can be manifest by use of rationalization or denial. This study explored appraisal distortion as an evaluative and moral process that occurs during partner conflict, particularly when it becomes contemptuous and aggressive. Using a philosophical base that is grounded in the ethical relationship, a model of appraisal distortion and couple conflict was created using constructivist grounded theory methods. The theoretical concepts derived from the data show relationships between one's relational stance, appraisal distortion, and verbal and physical aggression. This model implies that helping individuals take responsibility for appraisals is important in treating conflict.

A holistic calibration method with iterative distortion compensation for stereo deflectometry

Science.gov (United States)

Xu, Yongjia; Gao, Feng; Zhang, Zonghua; Jiang, Xiangqian

2018-07-01

This paper presents a novel holistic calibration method for stereo deflectometry system to improve the system measurement accuracy. The reconstruction result of stereo deflectometry is integrated with the calculated normal data of the measured surface. The calculation accuracy of the normal data is seriously influenced by the calibration accuracy of the geometrical relationship of the stereo deflectometry system. Conventional calibration approaches introduce form error to the system due to inaccurate imaging model and distortion elimination. The proposed calibration method compensates system distortion based on an iterative algorithm instead of the conventional distortion mathematical model. The initial value of the system parameters are calculated from the fringe patterns displayed on the systemic LCD screen through a reflection of a markless flat mirror. An iterative algorithm is proposed to compensate system distortion and optimize camera imaging parameters and system geometrical relation parameters based on a cost function. Both simulation work and experimental results show the proposed calibration method can significantly improve the calibration and measurement accuracy of a stereo deflectometry. The PV (peak value) of measurement error of a flat mirror can be reduced to 69.7 nm by applying the proposed method from 282 nm obtained with the conventional calibration approach.

High temperature reactor safety and environment

International Nuclear Information System (INIS)

Brisbois, J.; Charles, J.

1975-01-01

High-temperature reactors are endowed with favorable safety and environmental factors resulting from inherent design, main-component safety margins, and conventional safety systems. The combination of such characteristics, along with high yields, prove in addition, that such reactors are plagued with few problems, can be installed near users, and broaden the recourse to specific power, therefore fitting well within a natural environment [fr

High-resolution mapping of two-dimensional lattice distortions in ion-implanted crystals from X-ray diffractometry data

International Nuclear Information System (INIS)

Nikulin, A.Y.; Gureyev, T.E.; Stevenson, A.W.; Wilkins, S.W.; Hashizume, H.; Cookson, D.

1996-01-01

The triple-crystal synchrotron X-ray diffractometry data described in Nikulin, Stevenson, Hashizume, Wilkins, Foran, Cookson and Garrett (J. Appl. Cryst. 28, 57-60 (1995)) has been analyzed to map out two-dimensional (2D) lattice distortions in silicon (111) crystals implanted with B + ions of 100 keV energy through a periodic SiO 2 strip pattern. The lateral periodic structure produced a series of satellite reflections associated with the 111 Bragg peak. The 2D reconstruction incorporates the use of the Petrashen-Chukhovskii method, which retrieves the phases of the Bragg waves for these satellite reflections, together with that for the fundamental. The finite Fourier series is then synthesized with the relative phases determined. Localized distortions perpendicular to the surface arising from deposited B + ions in near-surface layers of the crystal are clearly displayed with spatial resolutions of 0.016 and 0.265 μm in the depth and lateral directions respectively. For a sample with the oxide layer removed from the surface, two equally plausible strain maps have been obtained by assigning relative phases to eleven satellites using a sequential trial method and a minimum-energy method. Failed map reconstructions for the oxide-covered sample are discussed in terms of the non-unique solutions of the Petrashen-Chukhovskii phase-recovery algorithm and the ambiguous phases determined for the satellites. 16 refs., 8 figs

DISTORTION ANALYSIS OF TILL -WALLED BOX GIRDERS

African Journals Online (AJOL)

NIJOTECH

bridges, buildings, motor vehicles, ships and aircrafts. Due to thinness of the box walls, generalized loads applied to this structure give rise to warping and distortion of ..... Recommendation for Design of. Intermediate Diaphragms in Box. Girders, Transactions of Japanese. Society of Civil Engineers, Vol. 14,1984, pp 121-126.

A real-time 3D scanning system for pavement distortion inspection

International Nuclear Information System (INIS)

Li, Qingguang; Yao, Ming; Yao, Xun; Xu, Bugao

2010-01-01

Pavement distortions, such as rutting and shoving, are the common pavement distress problems that need to be inspected and repaired in a timely manner to ensure ride quality and traffic safety. This paper introduces a real-time, low-cost inspection system devoted to detecting these distress features using high-speed 3D transverse scanning techniques. The detection principle is the dynamic generation and characterization of the 3D pavement profile based on structured light triangulation. To improve the accuracy of the system, a multi-view coplanar scheme is employed in the calibration procedure so that more feature points can be used and distributed across the field of view of the camera. A sub-pixel line extraction method is applied for the laser stripe location, which includes filtering, edge detection and spline interpolation. The pavement transverse profile is then generated from the laser stripe curve and approximated by line segments. The second-order derivatives of the segment endpoints are used to identify the feature points of possible distortions. The system can output the real-time measurements and 3D visualization of rutting and shoving distress in a scanned pavement

FORMALIZING PRODUCT COST DISTORTION: The Impact of Volume-Related Allocation Bases on Cost Information

Directory of Open Access Journals (Sweden)

Johnny Jermias

2003-09-01

Full Text Available The purpose o f this study is to formally analyze product cost distortions resulting from the process of allocating costs to products based on Activity-Based Costing (ABC and the conventional product costing systems. The model developed in this paper rigorously shows the impact of treating costs that are not volume related as if they are. The model demonstrates that the source of product cost distortion is the difference between the proportion of driver used by each product in ABC and the proportion of the base used by the same product in the conventional costing systems. The difference arises because the conventional costing systems ignore the existence of batch-related and product-related costs. The model predicts a positive association between volume and size diversity with product cost distortions. When interaction between volume and size diversity exists, the distortion is either mitigated or exacerbated. The magnitude of the distortion is jointly determined by the size of the differences and the size of the total indirect costs.

The effect of the observer vantage point on perceived distortions in linear perspective images.

Science.gov (United States)

Todorović, Dejan

2009-01-01

Some features of linear perspective images may look distorted. Such distortions appear in two drawings by Jan Vredeman de Vries involving perceived elliptical, instead of circular, pillars and tilted, instead of upright, columns. Distortions may be due to factors intrinsic to the images, such as violations of the so-called Perkins's laws, or factors extrinsic to them, such as observing the images from positions different from their center of projection. When the correct projection centers for the two drawings were reconstructed, it was found that they were very close to the images and, therefore, practically unattainable in normal observation. In two experiments, enlarged versions of images were used as stimuli, making the positions of the projection centers attainable for observers. When observed from the correct positions, the perceived distortions disappeared or were greatly diminished. Distortions perceived from other positions were smaller than would be predicted by geometrical analyses, possibly due to flatness cues in the images. The results are relevant for the practical purposes of creating faithful impressions of 3-D spaces using 2-D images.

Assessing Fan Flutter Stability in the Presence of Inlet Distortion Using One-way and Two-way Coupled Methods

Science.gov (United States)

Herrick, Gregory P.

2014-01-01

Concerns regarding noise, propulsive efficiency, and fuel burn are inspiring aircraft designs wherein the propulsive turbomachines are partially (or fully)embedded within the airframe; such designs present serious concerns with regard to aerodynamic and aeromechanic performance of the compression system in response to inlet distortion. Previously, a preliminary design of a forward-swept high-speed fan exhibited flutter concerns in clean-inlet flows, and the present author then studied this fan further in the presence of off-design distorted in-flows. A three-dimensional, unsteady, Navier-Stokes computational fluid dynamics code is applied to analyze and corroborate fan performance with clean inlet flow. This code, already validated in its application to assess aerodynamic damping of vibrating blades at various flow conditions using a loosely-coupled approach, is modified to include a tightly-coupled aeroelastic simulation capability, and then loosely-coupled and tightly-coupled methods arecompared in their evaluation of flutter stability in distorted in-flows.

Can journalistic "false balance" distort public perception of consensus in expert opinion?

Science.gov (United States)

Koehler, Derek J

2016-03-01

Media critics have expressed concern that journalistic "false balance" can distort the public's perceptions of what ought to be noncontroversial subjects (e.g., climate change). I report several experiments testing the influence of presenting conflicting comments from 2 experts who disagree on an issue (balance condition) in addition to a complete count of the number of experts on a panel who favor either side. Compared with a control condition, who received only the complete count, participants in the balance condition gave ratings of the perceived agreement among the experts that did not discriminate as clearly between issues with and without strong expert consensus. Participants in the balance condition also perceived less agreement among the experts in general, and were less likely to think that there was enough agreement among experts on the high-consensus issues to guide government policy. Evidently, "false balance" can distort perceptions of expert opinion even when participants would seem to have all the information needed to correct for its influence. (c) 2016 APA, all rights reserved).

Standard Practice for Optical Distortion and Deviation of Transparent Parts Using the Double-Exposure Method

CERN Document Server

American Society for Testing and Materials. Philadelphia

2009-01-01

1.1 This photographic practice determines the optical distortion and deviation of a line of sight through a simple transparent part, such as a commercial aircraft windshield or a cabin window. This practice applies to essentially flat or nearly flat parts and may not be suitable for highly curved materials. 1.2 Test Method F 801 addresses optical deviation (angluar deviation) and Test Method F 2156 addresses optical distortion using grid line slope. These test methods should be used instead of Practice F 733 whenever practical. 1.3 This standard does not purport to address the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Preliminary Results of the Determination of Inlet-Pressure Distortion Effects on Compressor Stall and Altitude Operating Limits of the J57-P-1 Turbojet Engine

Science.gov (United States)

Wallner, L. E.; Lubick, R. J.; Chelko, L. J.

1955-01-01

During an investigation of the J57-P-1 turbojet engine in the Lewis altitude wind tunnel, effects of inlet-flow distortion on engine stall characteristics and operating limits were determined. In addition to a uniform inlet-flow profile, the inlet-pressure distortions imposed included two radial, two circumferential, and one combined radial-circumferential profile. Data were obtained over a range of compressor speeds at an altitude of 50,000 and a flight Mach number of 0.8; in addition, the high- and low-speed engine operating limits were investigated up to the maximum operable altitude. The effect of changing the compressor bleed position on the stall and operating limits was determined for one of the inlet distortions. The circumferential distortions lowered the compressor stall pressure ratios; this resulted in less fuel-flow margin between steady-state operation and compressor stall. Consequently, the altitude operating Limits with circumferential distortions were reduced compared with the uniform inlet profile. Radial inlet-pressure distortions increased the pressure ratio required for compressor stall over that obtained with uniform inlet flow; this resulted in higher altitude operating limits. Likewise, the stall-limit fuel flows required with the radial inlet-pressure distortions were considerably higher than those obtained with the uniform inlet-pressure profile. A combined radial-circumferential inlet distortion had effects on the engine similar to the circumferential distortion. Bleeding air between the two compressors eliminated the low-speed stall limit and thus permitted higher altitude operation than was possible without compressor bleed.

[Signal analysis and spectrum distortion correction for tunable diode laser absorption spectroscopy system].

Science.gov (United States)

Bao, Wei-Yi; Zhu, Yong; Chen, Jun; Chen, Jun-Qing; Liang, Bo

2011-04-01

In the present paper, the signal of a tunable diode laser absorption spectroscopy (TDLAS) trace gas sensing system, which has a wavelength modulation with a wide range of modulation amplitudes, is studied based on Fourier analysis method. Theory explanation of spectrum distortion induced by laser intensity amplitude modulation is given. In order to rectify the spectrum distortion, a method of synchronous amplitude modulation suppression by a variable optical attenuator is proposed. To validate the method, an experimental setup is designed. Absorption spectrum measurement experiments on CO2 gas were carried out. The results show that the residual laser intensity modulation amplitude of the experimental system is reduced to -0.1% of its original value and the spectrum distortion improvement is 92% with the synchronous amplitude modulation suppression. The modulation amplitude of laser intensity can be effectively reduced and the spectrum distortion can be well corrected by using the given correction method and system. By using a variable optical attenuator in the TDLAS (tunable diode laser absorption spectroscopy) system, the dynamic range requirements of photoelectric detector, digital to analog converter, filters and other aspects of the TDLAS system are reduced. This spectrum distortion correction method can be used for online trace gas analyzing in process industry.

Over-exposure effects on the distortion product otoacoustic emission

DEFF Research Database (Denmark)

Reuter, Karen

, however. In the present study it was investigated, whether Distortion Product OtoAcoustic Emission (DPOAE) parameters exist, which indicate the early stage of a hearing loss. DPOAE was obtained with high frequency resolution, and its characteristic spectral fine structure was analyzed. Data of subjects...... belonging to different groups of age and exposure history were obtained and compared. Controlled sound/ noise exposure experiments were performed to observe changes in DPOAE characteristics. The DPOAE of all tested subjects feature the typical fine structure pattern. The fine structure pattern is highly...... individual and stable over time. No unequivocal relation between the characteristics of the DPOAE fine structure and the state of hearing could be found. It is suggested to eliminate the DPOAE fine structure in the DPOAE measurement and to establish a reference zero from a large amount of DPOAE data...

Distortion product otoacoustic emission fine structure of symphony orchestra musicians

DEFF Research Database (Denmark)

Reuter, Karen; Hammershøi, Dorte

2006-01-01

Otoacoustic emissions (OAE) are sounds produced by the healthy inner ear. They can be measured as low-level signals in the ear canal and are used to monitor the functioning of outer hair cells.Several studies indicate that OAE might be a more sensitive measure to detect early noise-induced hearing...... losses than puretone audiometry. The distortion product otoacoustic emission (DPOAE) fine structure is obtained when the ear is stimulated by dual tone stimuli using a high frequency resolution. It is characterized by quasi-periodic variations across frequency, as it can be observed in the hearing...

Rate-distortion functions of non-stationary Markoff chains and their block-independent approximations

OpenAIRE

Agarwal, Mukul

2018-01-01

It is proved that the limit of the normalized rate-distortion functions of block independent approximations of an irreducible, aperiodic Markoff chain is independent of the initial distribution of the Markoff chain and thus, is also equal to the rate-distortion function of the Markoff chain.

Characterization of system-related geometric distortions in MR images employed in Gamma Knife radiosurgery applications

Science.gov (United States)

Pappas, E. P.; Seimenis, I.; Moutsatsos, A.; Georgiou, E.; Nomikos, P.; Karaiskos, P.

2016-10-01

This work provides characterization of system-related geometric distortions present in MRIs used in Gamma Knife (GK) stereotactic radiosurgery (SRS) treatment planning. A custom-made phantom, compatible with the Leksell stereotactic frame model G and encompassing 947 control points (CPs), was utilized. MR images were obtained with and without the frame, thus allowing discrimination of frame-induced distortions. In the absence of the frame and following compensation for field inhomogeneities, measured average CP disposition owing to gradient nonlinearities was 0.53 mm. In presence of the frame, contrarily, detected distortion was greatly increased (up to about 5 mm) in the vicinity of the frame base due to eddy currents induced in the closed loop of its aluminum material. Frame-related distortion was obliterated at approximately 90 mm from the frame base. Although the region with the maximum observed distortion may not lie within the GK treatable volume, the presence of the frame results in distortion of the order of 1.5 mm at a 7 cm distance from the center of the Leksell space. Additionally, severe distortions observed outside the treatable volume could possibly impinge on the delivery accuracy mainly by adversely affecting the registration process (e.g. the position of the lower part of the N-shaped fiducials used to define the stereotactic space may be miss-registered). Images acquired with a modified version of the frame developed by replacing its front side with an acrylic bar, thus interrupting the closed aluminum loop and reducing the induced eddy currents, were shown to benefit from relatively reduced distortion. System-related distortion was also identified in patient MR images. Using corresponding CT angiography images as a reference, an offset of 1.1 mm was detected for two vessels lying in close proximity to the frame base, while excellent spatial agreement was observed for a vessel far apart from the frame base.

Image Registration to Compensate for EPI Distortion in Patients with Brain Tumors: An Evaluation of Tract-Specific Effects.

Science.gov (United States)

Albi, Angela; Meola, Antonio; Zhang, Fan; Kahali, Pegah; Rigolo, Laura; Tax, Chantal M W; Ciris, Pelin Aksit; Essayed, Walid I; Unadkat, Prashin; Norton, Isaiah; Rathi, Yogesh; Olubiyi, Olutayo; Golby, Alexandra J; O'Donnell, Lauren J

2018-03-01

Diffusion magnetic resonance imaging (dMRI) provides preoperative maps of neurosurgical patients' white matter tracts, but these maps suffer from echo-planar imaging (EPI) distortions caused by magnetic field inhomogeneities. In clinical neurosurgical planning, these distortions are generally not corrected and thus contribute to the uncertainty of fiber tracking. Multiple image processing pipelines have been proposed for image-registration-based EPI distortion correction in healthy subjects. In this article, we perform the first comparison of such pipelines in neurosurgical patient data. Five pipelines were tested in a retrospective clinical dMRI dataset of 9 patients with brain tumors. Pipelines differed in the choice of fixed and moving images and the similarity metric for image registration. Distortions were measured in two important tracts for neurosurgery, the arcuate fasciculus and corticospinal tracts. Significant differences in distortion estimates were found across processing pipelines. The most successful pipeline used dMRI baseline and T2-weighted images as inputs for distortion correction. This pipeline gave the most consistent distortion estimates across image resolutions and brain hemispheres. Quantitative results of mean tract distortions on the order of 1-2 mm are in line with other recent studies, supporting the potential need for distortion correction in neurosurgical planning. Novel results include significantly higher distortion estimates in the tumor hemisphere and greater effect of image resolution choice on results in the tumor hemisphere. Overall, this study demonstrates possible pitfalls and indicates that care should be taken when implementing EPI distortion correction in clinical settings. Copyright © 2018 by the American Society of Neuroimaging.

H∞ Robust Current Control for DFIG Based Wind Turbine subject to Grid Voltage Distortions

DEFF Research Database (Denmark)

Wang, Yun; Wu, Qiuwei; Gong, Wenming

2016-01-01

This paper proposes an H∞ robust current controller for doubly fed induction generator (DFIG) based wind turbines (WTs) subject to grid voltage distortions. The controller is to mitigate the impact of the grid voltage distortions on rotor currents with DFIG parameter perturbation. The grid voltage...... distortions considered include asymmetric voltage dips and grid background harmonics. An uncertain DFIG model is developed with uncertain factors originating from distorted stator voltage, and changed generator parameters due to the flux saturation effect, the skin effect, etc. Weighting functions...... are designed to efficiently track the unbalanced current components and the 5th and 7th background harmonics. The robust stability (RS) and robust performance (RP) of the proposed controller are verified by the structured singular value µ. The performance of the H∞ robust current controller was demonstrated...

Impact of the MLC on the MRI field distortion of a prototype MRI-linac

International Nuclear Information System (INIS)

Kolling, Stefan; Keall, Paul; Oborn, Brad

2013-01-01

Purpose: To cope with intrafraction tumor motion, integrated MRI-linac systems for real-time image guidance are currently under development. The multileaf collimator (MLC) is a key component in every state-of-the-art radiotherapy treatment system, allowing for accurate field shaping and tumor tracking. This work quantifies the magnetic impact of a widely used MLC on the MRI field homogeneity for such a modality.Methods: The finite element method was employed to model a MRI-linac assembly comprised of a 1.0 T split-bore MRI magnet and the key ferromagnetic components of a Varian Millennium 120 MLC, namely, the leaves and motors. Full 3D magnetic field maps of the system were generated. From these field maps, the peak-to-peak distortion within the MRI imaging volume was evaluated over a 30 cm diameter sphere volume (DSV) around the isocenter and compared to a maximum preshim inhomogeneity of 300 μT. Five parametric studies were performed: (1) The source-to-isocenter distance (SID) was varied from 100 to 200 cm, to span the range of a compact system to that with lower magnetic coupling. (2) The MLC model was changed from leaves only to leaves with motors, to determine the contribution to the total distortion caused by MLC leaves and motors separately. (3) The system was configured in the inline or perpendicular orientation, i.e., the linac treatment beam was oriented parallel or perpendicular to the magnetic field direction. (4) The treatment field size was varied from 0 × 0 to 20×20 cm 2 , to span the range of clinical treatment fields. (5) The coil currents were scaled linearly to produce magnetic field strengths B 0 of 0.5, 1.0, and 1.5 T, to estimate how the MLC impact changes with B 0 .Results: (1) The MLC-induced MRI field distortion fell continuously with increasing SID. (2) MLC leaves and motors were found to contribute to the distortion in approximately equal measure. (3) Due to faster falloff of the fringe field, the field distortion was

The influence of head frame distortions on stereotactic localization and targeting

Energy Technology Data Exchange (ETDEWEB)

Treuer, H; Hunsche, S; Hoevels, M; Luyken, K; Maarouf, M; Voges, J; Sturm, V [Department of Stereotaxy and Functional Neurosurgery, University of Cologne, 50924 Cologne (Germany)

2004-09-07

A strong attachment of a stereotactic head frame to the patient's skull may cause distortions of the head frame. The aim of this work was to identify possible distortions of the head frame, to measure the degree of distortion occurring in clinical practice and to investigate its influence on stereotactic localization and targeting. A model to describe and quantify the distortion of the Riechert-Mundinger (RM) head frame was developed. Distortions were classified as (a) bending and (b) changes from the circular ring shape. Ring shape changes were derived from stereotactic CT scans and frame bending was determined from intraoperative stereotactic x-ray images of patients with implanted {sup 125}I-seeds acting as landmarks. From the examined patient data frame bending was determined to be 0.74 mm {+-} 0.32 mm and 1.30 mm in maximum. If a CT-localizer with a top ring is used, frame bending has no influence on stereotactic CT-localization. In stereotactic x-ray localization, frame bending leads to an overestimation of the z-coordinate by 0.37 mm {+-} 0.16 mm on average and by 0.65 mm in maximum. The accuracy of patient positioning in radiosurgery is not affected by frame bending. But in stereotactic surgery with an RM aiming bow trajectory displacements are expected. These displacements were estimated to be 0.36 mm {+-} 0.16 mm (max. 0.74 mm) at the target point and 0.65 mm {+-} 0.30 mm (max. 1.31 mm) at the entry point level. Changes from the circular ring shape are small and do not compromise the accuracy of stereotactic targeting and localization. The accuracy of CT-localization was found to be close to the resolution limit due to voxel size. Our findings for frame bending of the RM frame could be validated by statistical analysis and by comparison with an independent patient examination. The results depend on the stereotactic system and details of the localizers and instruments and also reflect our clinical practice. Therefore, a generalization is not possible

A Method for Harmonic Sources Detection based on Harmonic Distortion Power Rate

Science.gov (United States)

Lin, Ruixing; Xu, Lin; Zheng, Xian

2018-03-01

Harmonic sources detection at the point of common coupling is an essential step for harmonic contribution determination and harmonic mitigation. The harmonic distortion power rate index is proposed for harmonic source location based on IEEE Std 1459-2010 in the paper. The method only based on harmonic distortion power is not suitable when the background harmonic is large. To solve this problem, a threshold is determined by the prior information, when the harmonic distortion power is larger than the threshold, the customer side is considered as the main harmonic source, otherwise, the utility side is. A simple model of public power system was built in MATLAB/Simulink and field test results of typical harmonic loads verified the effectiveness of proposed method.

Technical Note: Harmonic analysis applied to MR image distortion fields specific to arbitrarily shaped volumes.

Science.gov (United States)

Stanescu, T; Jaffray, D

2018-05-25

Magnetic resonance imaging is expected to play a more important role in radiation therapy given the recent developments in MR-guided technologies. MR images need to consistently show high spatial accuracy to facilitate RT specific tasks such as treatment planning and in-room guidance. The present study investigates a new harmonic analysis method for the characterization of complex 3D fields derived from MR images affected by system-related distortions. An interior Dirichlet problem based on solving the Laplace equation with boundary conditions (BCs) was formulated for the case of a 3D distortion field. The second-order boundary value problem (BVP) was solved using a finite elements method (FEM) for several quadratic geometries - i.e., sphere, cylinder, cuboid, D-shaped, and ellipsoid. To stress-test the method and generalize it, the BVP was also solved for more complex surfaces such as a Reuleaux 9-gon and the MR imaging volume of a scanner featuring a high degree of surface irregularities. The BCs were formatted from reference experimental data collected with a linearity phantom featuring a volumetric grid structure. The method was validated by comparing the harmonic analysis results with the corresponding experimental reference fields. The harmonic fields were found to be in good agreement with the baseline experimental data for all geometries investigated. In the case of quadratic domains, the percentage of sampling points with residual values larger than 1 mm were 0.5% and 0.2% for the axial components and vector magnitude, respectively. For the general case of a domain defined by the available MR imaging field of view, the reference data showed a peak distortion of about 12 mm and 79% of the sampling points carried a distortion magnitude larger than 1 mm (tolerance intrinsic to the experimental data). The upper limits of the residual values after comparison with the harmonic fields showed max and mean of 1.4 mm and 0.25 mm, respectively, with only 1.5% of

Test of distorted wave kinematic coupling approximation calculations for knockout reactions

International Nuclear Information System (INIS)

Jain, A.K.

1990-01-01

A test has been devised to check the validity of conventional distorted-wave impulse approximation (DWIA) treatment of knockout reactions. The conventional DWIA formalism separates the three-body final state Schroedinger equation for a knockout reaction into two two-body Schroedinger equations by assuming an asymptotic constant value for the three-body coupling term commonly known as the kinematic coupling approximation (KCA). In the test case, which consists of an extreme asymmetric situation where one of the distorting optical potentials is assumed to vanish, the three-body final state Schroedinger equation can be solved exactly as a product of two two-body solutions using one particular set of relative coordinates. Large influence of the three-body coupling term is seen in the comparison of the exact and KCA results for (α,2α) and (p,pα) knockout reactions when the distorting optical potentials are weakly absorbing

ROLE OF FCA WELDING PROCESS PARAMETERS ON BEAD PROFILE, ANGULAR AND BOWING DISTORTION OF FERRITIC STAINLESS STEEL SHEETS

Directory of Open Access Journals (Sweden)

VENKATESAN M. V.

2014-02-01

Full Text Available This paper discusses the influence of flux cored arc welding (FCAW process parameters such as welding current, travel speed, voltage and CO2 shielding gas flow rate on bead profile, bowing distortion and angular distortion of 409 M ferritic stainless steel sheets of 2 mm thickness. The bowing and angular distortions of the welded plates were measured using a simple device called profile tracer and Vernier bevel protractor respectively. The study revealed that the FCAW process parameters have significant effect on bead profile, and distortion. The relationship between bead profile and distortions were analyzed. Most favorable process parameters that give uniform bead profile and minimum distortion for the weld are recommended for fabrication.

Labor Market Distortions in Côte d'Ivoire:

DEFF Research Database (Denmark)

Kristensen, Nicolai; Verner, Dorte

2008-01-01

This paper investigates the extent and nature of distortions in the labor market in the Republic of Côte d'Ivoire by using quantile regression analysis on employer-employee data from the manufacturing sector. We found that the labor markets in Côte d'Ivoire do not seem to be much distorted. Unions...... may influence employment through tenure but do not seem to influence wages directly except for vulnerable minorities that seem protected by unions. Establishment-size wage effects are pronounced and highest for white-collar workers. This may be explained by the efficiency wage theory, so that, even...... in the absence of unions, segmentation and inefficiencies will still be present as long as firms seek to retain their employees by paying wages above the market clearing level. The inefficiency arising from establishment-size wage effects can be mitigated by education....

Projective aspects on cognitive performance: distortions in emotional perception correlate with personality

Directory of Open Access Journals (Sweden)

Fabiano Koich Miguel

2016-01-01

Full Text Available Abstract Several approaches in psychology converge with the concept that individual characteristics may interfere with the perception and interpretation of the world. We hypothesized that such phenomenon could be identified in instruments that were not only projective techniques. The research’s goal was to study perceptive distortions in a cognitive test and their relations with personality instruments. Responses from 222 participants in the Computerized Test of Primary Emotions Perception (PEP were rated in distortion scores, which related to perceiving emotions that were not present. We used Spearman correlations between these scores and the Rorschach Inkblot test, Dimensional Clinical Personality Inventory, and tasks of Verbal and Abstract Reasoning. Results showed that the distortions were not related to intellectual abilities. Distortions of joy were associated with greater interest in interpersonal contact; love with positive view of the interactions and need for attention; fear with concerns about aggressiveness and autonomy; sadness with lower perception of damaged objects; disgust with feelings of loneliness; and anger with criticism avoidance, distrust, feelings of loneliness, and aggressive behaviour. The results support the proposal that altered perception of reality is related to affective or personality characteristics.

Unsteady Reynolds-averaged Navier-Stokes simulations of inlet distortion in the fan system of a gas-turbine aero-engine

Science.gov (United States)

Spotts, Nathan

As modern trends in commercial aircraft design move toward high-bypass-ratio fan systems of increasing diameter with shorter, nonaxisymmetric nacelle geometries, inlet distortion is becoming common in all operating regimes. The distortion may induce aerodynamic instabilities within the fan system, leading to catastrophic damage to fan blades, should the surge margin be exceeded. Even in the absence of system instability, the heterogeneity of the flow affects aerodynamic performance significantly. Therefore, an understanding of fan-distortion interaction is critical to aircraft engine system design. This thesis research elucidates the complex fluid dynamics and fan-distortion interaction by means of computational fluid dynamics (CFD) modeling of a complete engine fan system; including rotor, stator, spinner, nacelle and nozzle; under conditions typical of those encountered by commercial aircraft. The CFD simulations, based on a Reynolds-averaged Navier-Stokes (RANS) approach, were unsteady, three-dimensional, and of a full-annulus geometry. A thorough, systematic validation has been performed for configurations from a single passage of a rotor to a full-annulus system by comparing the predicted flow characteristics and aerodynamic performance to those found in literature. The original contributions of this research include the integration of a complete engine fan system, based on the NASA rotor 67 transonic stage and representative of the propulsion systems in commercial aircraft, and a benchmark case for unsteady RANS simulations of distorted flow in such a geometry under realistic operating conditions. This study is unique in that the complex flow dynamics, resulting from fan-distortion interaction, were illustrated in a practical geometry under realistic operating conditions. For example, the compressive stage is shown to influence upstream static pressure distributions and thus suppress separation of flow on the nacelle. Knowledge of such flow physics is

The Influence of Measurement Methodology on the Accuracy of Electrical Waveform Distortion Analysis

Science.gov (United States)

Bartman, Jacek; Kwiatkowski, Bogdan

2018-04-01

The present paper covers a review of documents that specify measurement methods of voltage waveform distortion. It also presents measurement stages of waveform components that are uncommon in the classic fundamentals of electrotechnics and signal theory, including the creation process of groups and subgroups of harmonics and interharmonics. Moreover, the paper discusses selected distortion factors of periodic waveforms and presents analyses that compare the values of these distortion indices. The measurements were carried out in the cycle per cycle mode and the measurement methodology that was used complies with the IEC 61000-4-7 norm. The studies showed significant discrepancies between the values of analyzed parameters.

Meet the 'entangled' fieldworker - Distorted (re)presentations in tourism research

DEFF Research Database (Denmark)

Jensen, Martin Trandberg

how photographic materialities, performativities and sensations contribute to new tourism knowledges. While highlighting the potential of distorted representation, the paper posits a cautionary note in regards to the influential role of academic journals in determining the qualities of visual data....... The paper exemplifies distorted representation through three impressionistic tales derived from ethnographic research on the European rail travel phenomenon, InterRail.......Tourism research has recently been informed by non-representational theories to highlight the socio-material, embodied and heterogeneous composition of tourist experiences. These advances have contributed to further reflexivity and called for novel ways to animate representations...

Identification and control of harmonic distortions report on Furnas experience

Energy Technology Data Exchange (ETDEWEB)

Mantuano Filho, Salvatore; Medeiros, Jose Roberto de; Bezerra, Luiz Roberto; Oliveira, Denise Borges de; Praca, Antonio Augusto Souza; Paiva Fontes, Marco Antonio de; Marques, Luiz Carlos Borges C. [FURNAS, Rio de Janeiro, RJ (Brazil)

1994-12-31

This paper describes FURNAS experience on identification and control of harmonic distortions obtained from conservation of system operation and research for solutions. Special attention is paid to the harmonic overload observed at Ibiuna substation, the receiving end of the FURNAS HVDC transmission of the Itaipu 50 Hz energy, and the solutions that have been adopted. Methods of measurement and digital simulation have been developed and successfully tested so far. The present stage of those methods will be described. Not less important is the need for a specific legislation on harmonic distortion as explained in this paper. (author) 6 refs., 2 figs.

Contrast distortion induced by modulation voltage in scanning capacitance microscopy

Science.gov (United States)

Chang, M. N.; Hu, C. W.; Chou, T. H.; Lee, Y. J.

2012-08-01

With a dark-mode scanning capacitance microscopy (SCM), we directly observed the influence of SCM modulation voltage (MV) on image contrasts. For electrical junctions, an extensive modulated area induced by MV may lead to noticeable changes in the SCM signal phase and intensity, resulting in a narrowed junction image and a broadened carrier concentration profile. This contrast distortion in SCM images may occur even if the peak-to-peak MV is down to 0.3 V. In addition, MV may shift the measured electrical junction depth. The balance of SCM signals components explain these MV-induced contrast distortions.

Study Progress of Physiological Responses in High Temperature Environment

Science.gov (United States)

Li, K.; Zheng, G. Z.; Bu, W. T.; Wang, Y. J.; Lu, Y. Z.

2017-10-01

Certain workers are exposed to high temperatures for a long time. Heat stress will result in a series of physiological responses, and cause adverse effects on the health and safety of workers. This paper summarizes the physiological changes of cardiovascular system, core temperature, skin temperature, water-electrolyte metabolism, alimentary system, neuroendocrine system, reaction time and thermal fatigue in high temperature environments. It can provide a theoretical guidance for labor safety in high temperature environment.

Corrections of residual fluorescence distortions for a glancing-emergence-angle x-ray-absorption technique

International Nuclear Information System (INIS)

Brewe, D.L.; Pease, D.M.; Budnick, J.I.

1994-01-01

Distortions appear in x-ray-absorption spectra obtained by monitoring the fluorescence from thick samples with concentrated absorbing species. The glancing-emergence-angle technique for obtaining spectra from this type of sample eliminates distortions from the measured spectra by monitoring the fluorescence leaving the sample at a small angle relative to the sample surface. This technique is limited by the small signal available from the inherently limited detector solid angle. In addition, no precise estimate of the required restriction on maximum emergent angle θ max has been available. We have calculated residual extended x-ray-absorption fine structure distortions as a function of θ max , and performed experimental tests of the calculations. These calculations provide a means to estimate the required detector geometry for negligible distortions, or alternatively, allow the use of a larger θ max , increasing the available signal, with the remaining residual distortions removed by application of the calculations. The calculations are also applicable to other detector geometries, and account for detectors subtending a large solid angle by an integration over the subtended angle. This represents an improvement over previous calculations. The application to more general detector configurations is also discussed

Performance of a Low Speed Axial Compressor Rotor Blade Row under Different Inlet Distortions

Directory of Open Access Journals (Sweden)

R. Taghavi Zenouz

2017-05-01

Full Text Available Responses of an axial compressor isolated rotor blade row to various inlet distortions have been investigated utilizing computational fluid dynamic technique. Distortions have been imposed by five screens of different geometries, but with the same blockage ratio. These screens were embedded upstream of the rotor blade row. Flow fields are simulated in detail for compressor design point and near stall conditions. Performance curves for distorted cases are extracted and compared to the undisturbed case. Flow simulations and consequent performance characteristics show that the worst cases belong to non-symmetric blockages, i.e., those of partial circumferential configurations. These cases produce the largest wakes which can disturb the flow, considerably. Superior performances correspond to the inner and outer continuous circumferential distortion screens. Since, they produce no significant disturbances to the main flow in comparison to the non-symmetric screens.

Large crystal structure distortion in DyB{sub 6} studied by X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Granovsky, S.A. E-mail: ser@plms.phys.msu.su; Markosyan, A.S

2003-03-01

A large magnetoelastic coupling induces a lattice distortion of a rhombohedral type in DyB{sub 6}. Below the quadrupolar ordering temperature T{sub Q}=31 K the cubic and the distorted phases coexist. The cubic phase disappears at 23 K, which was identified as the magnetic ordering point T{sub N}. In the magnetic phase the distortion (dl/l){sub 111} increases monotonically with decreasing temperature and reaches the value of 9x10{sup -3} at 8 K, which is one of the largest value known for cubic compounds.

Synchronization of cubic distortion spontaneous otoacoustic emissions

NARCIS (Netherlands)

van Dijk, P; Wit, HP

A spontaneous otoacoustic emission spectrum may contain equally spaced emission peaks. Then, two peaks, at frequencies, f(1) and f(2), respectively, apparently generate a distortion product at f(d)=2f(1)-f(2) [or 2f(2)-f(1)]. For the three emission peaks of nine of such triplets tin six emission

Prediction of windings temperature rise in induction motors supplied with distorted voltage

Energy Technology Data Exchange (ETDEWEB)

Gnacinski, P. [Gdynia Maritime University, Department of Ship Electrical Power Engineering, Morska Street 83, 81-225 Gdynia (Poland)

2008-04-15

One of the features of ship power systems is a different level and intensity of disturbances appearing during routine operation - the rms voltage value and frequency deviation, voltage unbalance and waveform voltage distortion. As a result, marine induction machines are exposed to overheating due to the lowered voltage quality. This paper is devoted to windings temperature rise prediction in marine induction cage machines supplied with distorted voltage, which means real voltage conditions. The proposed method of prediction does not require detailed knowledge of the thermal properties of a machine. Although the method was developed for marine induction motors, it is applicable for industry machines supplied with distorted voltage. It can also be generalized and used for estimation of the steady state windings temperature rise of any electrical machinery in various work conditions. (author)

Prediction of windings temperature rise in induction motors supplied with distorted voltage

International Nuclear Information System (INIS)

Gnacinski, P.

2008-01-01

One of the features of ship power systems is a different level and intensity of disturbances appearing during routine operation - the rms voltage value and frequency deviation, voltage unbalance and waveform voltage distortion. As a result, marine induction machines are exposed to overheating due to the lowered voltage quality. This paper is devoted to windings temperature rise prediction in marine induction cage machines supplied with distorted voltage, which means real voltage conditions. The proposed method of prediction does not require detailed knowledge of the thermal properties of a machine. Although the method was developed for marine induction motors, it is applicable for industry machines supplied with distorted voltage. It can also be generalized and used for estimation of the steady state windings temperature rise of any electrical machinery in various work conditions

An environment for high energy physics code development

International Nuclear Information System (INIS)

Wisinski, D.E.

1987-01-01

As the size and complexity of high energy experiments increase there will be a greater need for better software tools and new programming environments. If these are not commercially available, then we must build them ourselves. This paper describes a prototype programming environment featuring a new type of file system, a ''smart'' editor, and integrated file management tools. This environment was constructed under the IBM VM/SP operating system. It uses the system interpreter, the system editor and the NOMAD2 relational database management system to create a software ''shell'' for the programmer. Some extensions to this environment are explored. (orig.)

Decreasing Distortion Energies without Strain: Diazo-Selective 1,3-Dipolar Cycloadditions.

Science.gov (United States)

Gold, Brian; Aronoff, Matthew R; Raines, Ronald T

2016-07-15

The diazo group has attributes that complement those of the azido group for applications in chemical biology. Here, we use computational analyses to provide insights into the chemoselectivity of the diazo group in 1,3-dipolar cycloadditions. Dipole distortion energies are responsible for ∼80% of the overall energetic barrier for these reactions. Here, we show that diazo compounds, unlike azides, provide an opportunity to decrease that barrier substantially without introducing strain into the dipolarophile. The ensuing rate enhancement is due to the greater nucleophilic character of a diazo group compared to that of an azido group, which can accommodate decreased distortion energies without predistortion. The tuning of distortion energies with substituents in a diazo compound or dipolarophile can enhance reactivity and selectivity in a predictable manner. Notably, these advantages of diazo groups are amplified in water. Our findings provide a theoretical framework that can guide the design and application of both diazo compounds and azides in "orthogonal" contexts, especially for biological investigations.

Irregular Distortion of The Erythrocytes (Acanthocytes, Spur Cells in Senile Dementia

Directory of Open Access Journals (Sweden)

H. B. Goodall

1994-01-01

Full Text Available An excess of irregularly di storted red cells with spiked forms (acanthocytes. spur cells has been found in a substantial minority of patient s with seni le dementia of Alzheimer type (7 of 50 patients, 3 of 21 men and 4 of 29 women. Of 100 control patients, 42 men and 58 women, 5 (men and 2 women showed comparable distortion, but, of these, one man may well have incipient dementia and the others had serious organic di seases which may be associated with comparable erythrocytic changes. The cause of the distortion is not yet clear, but the presence of occasional giant erythrocytes in the absence of general macrocytosis suggests a possible abnormality of cell membrane synthes is. This distortion may be a useful marker in patients with loss of memory. Whether it is a manifestation of a haemopoietic clone or a constitutional anomaly associated with Alzheimer’s disease remains to be seen.

On the distortions in calculated GW parameters during slanted atmospheric soundings

Science.gov (United States)

de la Torre, Alejandro; Alexander, Peter; Schmidt, Torsten; Llamedo, Pablo; Hierro, Rodrigo

2018-03-01

The significant distortions introduced in the measured atmospheric gravity wavelengths by soundings other than those in vertical and horizontal directions, are discussed as a function of the elevation angle of the sounding path and the gravity wave aspect ratio. Under- or overestimation of real vertical wavelengths during the measurement process depends on the value of these two parameters. The consequences of these distortions on the calculation of the energy and the vertical flux of horizontal momentum are analyzed and discussed in the context of two experimental limb satellite setups: GPS-LEO radio occultations and TIMED/SABER ((Atmosphere using Broadband Emission Radiometry/Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics)) measurements. Possible discrepancies previously found between the momentum flux calculated from satellite temperature profiles, on site and from model simulations, may to a certain degree be attributed to these distortions. A recalculation of previous momentum flux climatologies based on these considerations seems to be a difficult goal.

Observation of distorted Maxwell-Boltzmann distribution of epithermal ions in LHD

Science.gov (United States)

Ida, K.; Kobayashi, T.; Yoshinuma, M.; Akiyama, T.; Tokuzawa, T.; Tsuchiya, H.; Itoh, K.; LHD Experiment Group

2017-12-01

A distorted Maxwell-Boltzmann distribution of epithermal ions is observed associated with the collapse of energetic ions triggered by the tongue shaped deformation. The tongue shaped deformation is characterized by the plasma displacement localized in the toroidal, poloidal, and radial directions at the non-rational magnetic flux surface in toroidal plasma. Moment analysis of the ion velocity distribution measured with charge exchange spectroscopy is studied in order to investigate the impact of tongue event on ion distribution. A clear non-zero skewness (3rd moment) and kurtosis (4th moment -3) of ion velocity distribution in the epithermal region (within three times of thermal velocity) is observed after the tongue event. This observation indicates the clear evidence of the distortion of ion velocity distribution from Maxwell-Boltzmann distribution. This distortion from Maxwell-Boltzmann distribution is observed in one-third of plasma minor radius region near the plasma edge and disappears in the ion-ion collision time scale.

Quantitation of structural distortion with gradient-echo imaging techniques

International Nuclear Information System (INIS)

Tien, R.D.; Schwaighofer, B.W.; Hesselink, J.R.; Chu, P.K.

1990-01-01

This paper determines the structural distortion and measurement error associated with fast MR imaging of the spinal neural foramina. Dry skeletal specimens and a thin cadaveric sagittal section through the neural foramina were placed in a water bath. MR images were obtained with a 1.5-T unit in different planes and with various pulse sequences. The size and shape of each neural foramen were carefully measured on the images and on the skeletal specimens. Gradient-echo (GRE) techniques (gradient recalled acquisition in a steady state, MPGR, three-dimensional volume acquisition) resulted in structural distortion in up to 10% on the fresh skeleton and 30% of the dry skeleton specimens when a small TE was used (the foramina appear narrower on the images)

Sensitivity Analysis of Structures by Virtual Distortion Method

DEFF Research Database (Denmark)

Gierlinski, J.T.; Holnicki-Szulc, J.; Sørensen, John Dalsgaard

1991-01-01

are used in structural optimization, see Haftka [4]. The recently developed Virtual Distortion Method (VDM) is a numerical technique which offers an efficient approach to calculation of the sensitivity derivatives. This method has been orginally applied to structural remodelling and collapse analysis, see...

New quaternary oxides with both families of second-order Jahn–Teller (SOJT) distortive cations: Solid-state synthesis, structure determination, and characterization of YNbTe{sub 2}O{sub 8} and YNbSe{sub 2}O{sub 8}

Energy Technology Data Exchange (ETDEWEB)

Kim, Yeong Hun [Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756 (Korea, Republic of); Jeon, Beom-Yong; You, Tae-Soo [Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Ok, Kang Min, E-mail: kmok@cau.ac.kr [Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756 (Korea, Republic of)

2015-07-15

Graphical abstract: Ball-and-stick representation of YNbTe{sub 2}O{sub 8} composed of polyhedra of SOJT distortive cations, i.e., NbO{sub 6} and TeO{sub 3}, in the ac-plane. - Highlights: • Two novel tellurite and selenite (YNbQ{sub 2}O{sub 8}; Q = Te and Se) are synthesized. • YNbQ{sub 2}O{sub 8} possess both families of second-order Jahn–Teller distortive cations. • The distortive environments and bonding nature are supported by electronic structure calculations. - Abstract: Two novel quaternary mixed metal tellurite and selenite, YNbTe{sub 2}O{sub 8} and YNbSe{sub 2}O{sub 8}, respectively, have been synthesized through standard solid-state reactions using Y{sub 2}O{sub 3}, Nb{sub 2}O{sub 5}, TeO{sub 2} or SeO{sub 2} as reagents. Single crystal X-ray and powder neutron diffraction analyses have been utilized to determine the structures of the reported materials. YNbTe{sub 2}O{sub 8} and YNbSe{sub 2}O{sub 8} are isostructural to each other and crystallize in the monoclinic centrosymmetric space group, C2/m (No. 12). Due to the two families of constituent second-order Jahn–Teller (SOJT) distortive cations, i.e., Nb{sup 5+} and Te{sup 4+}/Se{sup 4+}, local asymmetric environments occur from the three-dimensional frameworks. Intra-octahedral distortions along the local C{sub 4} direction and asymmetric trigonal pyramidal coordination moieties generated by stereoactive lone pairs are observed from the NbO{sub 6} octahedra and TeO{sub 3} (or SeO{sub 3}) polyhedra, respectively. Thermogravimetric analysis, infrared and UV–vis diffuse reflectance spectroscopies, elemental analysis, out-of-center distortions, dipole moment calculations, and electronic structure calculations for the reported materials are presented.

Distortion of CAD-CAM-fabricated implant-fixed titanium and zirconia complete dental prosthesis frameworks.

Science.gov (United States)

Al-Meraikhi, Hadi; Yilmaz, Burak; McGlumphy, Edwin; Brantley, William A; Johnston, William M

2018-01-01

Computer-aided design and computer-aided manufacturing (CAD-CAM)-fabricated titanium and zirconia implant-supported fixed dental prostheses have become increasingly popular for restoring patients with complete edentulism. However, the distortion level of these frameworks is not well known. The purpose of this in vitro study was to compare the 3-dimensional (3D) distortion of CAD-CAM zirconia and titanium implant-fixed screw-retained complete dental prostheses. A master edentulous model with 4 implants at the positions of the maxillary first molars and canines was used. Multiunit abutments (Nobel Biocare) secured to the model were digitally scanned using scan bodies and a laboratory scanner (S600 ARTI; Zirkonzahn). Titanium (n=5) and zirconia (n=5) frameworks were milled using a CAD-CAM system (Zirkonzahn M1; Zirkonzahn). All frameworks were scanned using an industrial computed tomography (CT) scanner (Nikon/X-Tek XT H 225kV MCT Micro-Focus). The direct CT scans were reconstructed to generate standard tessellation language (STL) files. To calculate the 3D distortion of the frameworks, STL files of the CT scans were aligned to the CAD model using a sum of the least squares best-fit algorithm. Surface comparison points were placed on the CAD model on the midfacial aspect of all teeth. The 3D distortion of each direct scan to the CAD model was calculated. In addition, color maps of the scan-to-CAD comparison were constructed using a ±0.500 mm color scale range. Both materials exhibited distortion; however, no significant difference was found in the amount of distortion from the CAD model between the materials (P=.747). Absolute values of deviations from the CAD model were evident in the x and y plane and less so in the z direction. Zirconia and titanium frameworks showed similar 3D distortion compared with the CAD model for the tested CAD-CAM and implant systems. The distortion was more pronounced in the horizontal and sagittal plane than in the vertical plane

CDW (continuum distorted wave) type approximation for electron capture at large angles

International Nuclear Information System (INIS)

Fojon, O.A.; Maidagan, J.M.

1990-01-01

A calculation is made for the probability of electron capture in shell K at great angles using a second order symmetrical model used related to the continuum distorted wave (CDW) approximation. The influence of Coulomb distortion of nuclei is studied and compared with OBK and CIS type calculations. Numerical results are compared with experimental results of the collision of H + on C at intermediate energies. (Author). 19 refs., 2 figs

Rape-related cognitive distortions: Preliminary findings on the role of early maladaptive schemas.

Science.gov (United States)

Sigre-Leirós, Vera; Carvalho, Joana; Nobre, Pedro J

2015-01-01

Despite the important focus on the notion of cognitive distortions in the sexual offending area, the relevance of underlying cognitive schemas in sexual offenders has also been suggested. The aim of the present study was to investigate a potential relationship between Early Maladaptive Schemas (EMSs) and cognitive distortions in rapists. A total of 33 men convicted for rape completed the Bumby Rape Scale (BRS), the Young Schema Questionnaire - Short form-3 (YSQ-S3), the Brief Symptom Inventory (BSI), and the Socially Desirable Response Set Measure (SDRS-5). Results showed a significant relationship between the impaired limits schematic domain and the Justifying Rape dimension of the BRS. Specifically, after controlling for psychological distress levels and social desirability tendency, the entitlement/grandiosity schema from the impaired limits domain was a significant predictor of cognitive distortions related to Justifying Rape themes. Overall, despite preliminary, there is some evidence that the Young's Schema-Focused model namely the impaired limits dimension may contribute for the conceptualization of cognitive distortions in rapists and further investigation is recommended. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of galvanic distortions on magnetotelluric data: Interpretation ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

But in the case of field data the problem is ... The distorted data set is corrected using the MT response for DRS model and further ... ments, the apparent resistivity and phase at differ- ... from the telluric field, which is of galvanic or inductive ...

Applying image quality in cell phone cameras: lens distortion

Science.gov (United States)

Baxter, Donald; Goma, Sergio R.; Aleksic, Milivoje

2009-01-01

This paper describes the framework used in one of the pilot studies run under the I3A CPIQ initiative to quantify overall image quality in cell-phone cameras. The framework is based on a multivariate formalism which tries to predict overall image quality from individual image quality attributes and was validated in a CPIQ pilot program. The pilot study focuses on image quality distortions introduced in the optical path of a cell-phone camera, which may or may not be corrected in the image processing path. The assumption is that the captured image used is JPEG compressed and the cellphone camera is set to 'auto' mode. As the used framework requires that the individual attributes to be relatively perceptually orthogonal, in the pilot study, the attributes used are lens geometric distortion (LGD) and lateral chromatic aberrations (LCA). The goal of this paper is to present the framework of this pilot project starting with the definition of the individual attributes, up to their quantification in JNDs of quality, a requirement of the multivariate formalism, therefore both objective and subjective evaluations were used. A major distinction in the objective part from the 'DSC imaging world' is that the LCA/LGD distortions found in cell-phone cameras, rarely exhibit radial behavior, therefore a radial mapping/modeling cannot be used in this case.

Improved volumetric measurement of brain structure with a distortion correction procedure using an ADNI phantom.

Science.gov (United States)

Maikusa, Norihide; Yamashita, Fumio; Tanaka, Kenichiro; Abe, Osamu; Kawaguchi, Atsushi; Kabasawa, Hiroyuki; Chiba, Shoma; Kasahara, Akihiro; Kobayashi, Nobuhisa; Yuasa, Tetsuya; Sato, Noriko; Matsuda, Hiroshi; Iwatsubo, Takeshi

2013-06-01

Serial magnetic resonance imaging (MRI) images acquired from multisite and multivendor MRI scanners are widely used in measuring longitudinal structural changes in the brain. Precise and accurate measurements are important in understanding the natural progression of neurodegenerative disorders such as Alzheimer's disease. However, geometric distortions in MRI images decrease the accuracy and precision of volumetric or morphometric measurements. To solve this problem, the authors suggest a commercially available phantom-based distortion correction method that accommodates the variation in geometric distortion within MRI images obtained with multivendor MRI scanners. The authors' method is based on image warping using a polynomial function. The method detects fiducial points within a phantom image using phantom analysis software developed by the Mayo Clinic and calculates warping functions for distortion correction. To quantify the effectiveness of the authors' method, the authors corrected phantom images obtained from multivendor MRI scanners and calculated the root-mean-square (RMS) of fiducial errors and the circularity ratio as evaluation values. The authors also compared the performance of the authors' method with that of a distortion correction method based on a spherical harmonics description of the generic gradient design parameters. Moreover, the authors evaluated whether this correction improves the test-retest reproducibility of voxel-based morphometry in human studies. A Wilcoxon signed-rank test with uncorrected and corrected images was performed. The root-mean-square errors and circularity ratios for all slices significantly improved (p Wilcoxon signed-rank test, p test-retest reproducibility. The results showed that distortion was corrected significantly using the authors' method. In human studies, the reproducibility of voxel-based morphometry analysis for the whole gray matter significantly improved after distortion correction using the authors

Coupling effect of piezoelectric wafer transducers in distortions of primary Lamb wave modes

International Nuclear Information System (INIS)

Bijudas, C R; Mitra, M; Mujumdar, P M

2013-01-01

Piezoelectric wafer transducers (PWT) are widely used for Lamb wave based damage detection schemes. The size of the damage that can be detected is dependent on the wavelength of the Lamb wave employed. Thus it is essential to explore the higher frequency range within the (fundamental) bandwidth of S 0 and A 0 modes, however below the cut-off frequencies of A 1 and S 1 . It is observed that the Lamb wave modes S 0 and A 0 generated using PWT undergo distortion within this fundamental bandwidth. This behavior is experimentally observed for different PWT sizes and types. The nature of this observed distortion is very different from the distortion of wave modes due to dispersion. In addition, the distortion, in many cases, tends towards the appearance of new wave modes close to the S 0 and A 0 modes. To understand this experimental observation, a theoretical study is performed. First, finite element (FE) simulations of Lamb waves considering pin-force, thermal analogy, and couple field models of surface mounted PWT are carried out. These simulation studies reveal that the wavepacket distortion can be attributed mostly to electro-mechanical coupling effect of the PWT. Next, the dispersion plot of piezoelectric layer considering electro-mechanical coupling is obtained using spectral finite element (SFE) method. These dispersion characteristics of the PWT are found to be significantly different from the conventional Lamb wave dispersion characteristics and may explain the experimental observation. (paper)

Response distortion in personality measurement: born to deceive, yet capable of providing valid self-assessments?

Directory of Open Access Journals (Sweden)

STEPHAN DILCHERT

2006-09-01

Full Text Available This introductory article to the special issue of Psychology Science devoted to the subject of “Considering Response Distortion in Personality Measurement for Industrial, Work and Organizational Psychology Research and Practice” presents an overview of the issues of response distortion in personality measurement. It also provides a summary of the other articles published as part of this special issue addressing social desirability, impression management, self-presentation, response distortion, and faking in personality measurement in industrial, work, and organizational settings.

Molecular distortion and charge transfer effects in ZnPc/Cu(111)

KAUST Repository

Amin, B.; Nazir, S.; Schwingenschlö gl, Udo

2013-01-01

The adsorption geometry and electronic properties of a zinc-phthalocyanine molecule on a Cu(111) substrate are studied by density functional theory. In agreement with experiment, we find remarkable distortions of the molecule, mainly as the central Zn atom tends towards the substrate to minimize the Zn-Cu distance. As a consequence, the Zn-N chemical bonding and energy levels of the molecule are significantly modified. However, charge transfer induces metallic states on the molecule and therefore is more important for the ZnPc/Cu(111) system than the structural distortions.

Molecular distortion and charge transfer effects in ZnPc/Cu(111)

KAUST Repository

Amin, B.

2013-04-23

The adsorption geometry and electronic properties of a zinc-phthalocyanine molecule on a Cu(111) substrate are studied by density functional theory. In agreement with experiment, we find remarkable distortions of the molecule, mainly as the central Zn atom tends towards the substrate to minimize the Zn-Cu distance. As a consequence, the Zn-N chemical bonding and energy levels of the molecule are significantly modified. However, charge transfer induces metallic states on the molecule and therefore is more important for the ZnPc/Cu(111) system than the structural distortions.

Can components in distortion-product otoacoustic emissions be separated?

DEFF Research Database (Denmark)

Christensen, Anders Tornvig; W. Purcell, David; Christensen, Flemming

2012-01-01

Otoacoustic emissions are signals emitted from the cochlea, either spontaneously or evoked by stimuli. Measured with an acoustic probe sealed in the ear-canal, they reveal information about a part of the mechanism of hearing that is otherwise inaccessible. Outer hair cells in the cochlea work...... to improve hearing sensitivity by means of nonlinear amplification, which produces distortion. In the measurement of otoacoustic emissions, two tones can be delivered to the cochlea to invoke this nonlinearity and elicit the distortion-product otoacoustic emission (DPOAE). DPOAEs arise mainly from two...... spatially separated generation mechanisms, thus making interpretation of DPOAE measurements complicated. In this study, we test whether or not source separation by group delays is equivalent to separation by time delays – either result is equally interesting to understand given the complexity of the cochlea...

Analysis and validation of laser spot weld-induced distortion

Energy Technology Data Exchange (ETDEWEB)

Knorovsky, G.A.; Kanouff, M.P.; Maccallum, D.O.; Fuerschbach, P.W.

1999-12-09

Laser spot welding is an ideal process for joining small parts with tight tolerances on weld size, location, and distortion, particularly those with near-by heat sensitive features. It is also key to understanding the overlapping laser spot seam welding process. Rather than attempting to simulate the laser beam-to-part coupling (particularly if a keyhole occurs), it was measured by calorimetry. This data was then used to calculate the thermal and structural response of a laser spot welded SS304 disk using the finite element method. Five combinations of process parameter values were studied. Calculations were compared to experimental data for temperature and distortion profiles measured by thermocouples and surface profiling. Results are discussed in terms of experimental and modeling factors. The authors then suggest appropriate parameters for laser spot welding.

Internal process: what is abstraction and distortion process?

Science.gov (United States)

Fiantika, F. R.; Budayasa, I. K.; Lukito, A.

2018-03-01

Geometry is one of the branch of mathematics that plays a major role in the development of science and technology. Thus, knowing the geometry concept is needed for students from their early basic level of thinking. A preliminary study showed that the elementary students have difficulty in perceiving parallelogram shape in a 2-dimention of a cube drawing as a square shape. This difficulty makes the students can not solve geometrical problems correctly. This problem is related to the internal thinking process in geometry. We conducted the exploration of students’ internal thinking processes in geometry particularly in distinguishing the square and parallelogram shape. How the students process their internal thinking through distortion and abstraction is the main aim of this study. Analysis of the geometrical test and deep interview are used in this study to obtain the data. The result of this study is there are two types of distortion and abstraction respectively in which the student used in their internal thinking processes.

Effects of bending-torsional duct-induced swirl distortion on aerodynamic performance of a centrifugal compressor

Science.gov (United States)

Hou, Hongjuan; Wang, Leilei; Wang, Rui; Yang, Yanzhao

2017-04-01

A turbocharger compressor working in commercial vehicles, especially in some passenger cars, often works together with some pipes with complicated geometry as an air intake system, due to limit of available space in internal combustion engine compartments. These pipes may generate various distortions of physical parameters of the air at the inlet of the compressor and therefore the compressor aerodynamic performance deteriorates. Sometimes, the turbocharging engine fails to work at some operation points. This paper investigates the effects of various swirl distortions induced by different bending-torsional intake ducts on the aerodynamic performance of a turbocharger compressor by both 3D numerical simulations and experimental measurements. It was found that at the outlet of the pipes the different inlet ducts can generate different swirl distortions, twin vortices and bulk-like vortices with different rotating directions. Among them, the bulk-like vortices not only affect seriously the pressure distribution in the impeller domain, but also significantly deteriorate the compressor performance, especially at high flow rate region. And the rotating direction of the bulk-like vortices is also closely associated with the efficiency penalty. Besides the efficiency, the transient flow rate through a single impeller channel, or the asymmetric mass flow crossing the whole impeller, can be influenced by two disturbances. One is from the upstream bending-torsional ducts; other one is from the downstream volute.

A methodology to investigate the impact of image distortions on the radiation dose when using magnetic resonance images for planning

Science.gov (United States)

Yan, Yue; Yang, Jinzhong; Beddar, Sam; Ibbott, Geoffrey; Wen, Zhifei; Court, Laurence E.; Hwang, Ken-Pin; Kadbi, Mo; Krishnan, Sunil; Fuller, Clifton D.; Frank, Steven J.; Yang, James; Balter, Peter; Kudchadker, Rajat J.; Wang, Jihong

2018-04-01

We developed a novel technique to study the impact of geometric distortion of magnetic resonance imaging (MRI) on intensity-modulated radiation therapy treatment planning. The measured 3D datasets of residual geometric distortion (a 1.5 T MRI component of an MRI linear accelerator system) was fitted with a second-order polynomial model to map the spatial dependence of geometric distortions. Then the geometric distortion model was applied to computed tomography (CT) image and structure data to simulate the distortion of MRI data and structures. Fourteen CT-based treatment plans were selected from patients treated for gastrointestinal, genitourinary, thoracic, head and neck, or spinal tumors. Plans based on the distorted CT and structure data were generated (as the distorted plans). Dose deviations of the distorted plans were calculated and compared with the original plans to study the dosimetric impact of MRI distortion. The MRI geometric distortion led to notable dose deviations in five of the 14 patients, causing loss of target coverage of up to 3.68% and dose deviations to organs at risk in three patients, increasing the mean dose to the chest wall by up to 6.19 Gy in a gastrointestinal patient, and increases the maximum dose to the lung by 5.17 Gy in a thoracic patient.

The effect of band Jahn-Teller distortion on the magnetoresistivity of manganites: a model study

International Nuclear Information System (INIS)

Rout, G C; Panda, Saswati; Behera, S N

2011-01-01

We present a model study of magnetoresistance through the interplay of magnetisation, structural distortion and external magnetic field for the manganite systems. The manganite system is described by the Hamiltonian which consists of the s-d type double exchange interaction, Heisenberg spin-spin interaction among the core electrons, and the static and dynamic band Jahn-Teller (JT) interaction in the e g band. The relaxation time of the e g electron is found from the imaginary part of the Green's function using the total Hamiltonian consisting of the interactions due to the electron and phonon. The calculated resistivity exhibits a peak in the pure JT distorted insulating phase separating the low temperature metallic ferromagnetic phase and the high temperature paramagnetic phase. The resistivity is suppressed with the increase of the external magnetic field. The e g electron band splitting and its effect on magnetoresistivity is reported here. (paper)

The Cognitive Distortions Questionnaire (CD-Quest): Validation in a Sample of Adults with Social Anxiety Disorder

OpenAIRE

Kaplan, SC; Morrison, AS; Goldin, PR; Olino, TM; Heimberg, RG; Gross, JJ

2017-01-01

© 2017, Springer Science+Business Media New York. Cognitive distortions are thought to be central to the development and maintenance of anxiety disorders and are a widely acknowledged treatment target in cognitive-behavioral interventions. However, little research has focused on the measurement of cognitive distortions. The Cognitive Distortions Questionnaire (CD-Quest; de Oliveira, Trial-based cognitive therapy: A manual for clinicians, Routledge, New York, 2015), a brief, 15-item questionna...

Review and comparison of geometric distortion correction schemes in MR images used in stereotactic radiosurgery applications

Science.gov (United States)

Pappas, E. P.; Dellios, D.; Seimenis, I.; Moutsatsos, A.; Georgiou, E.; Karaiskos, P.

2017-11-01

In Stereotactic Radiosurgery (SRS), MR-images are widely used for target localization and delineation in order to take advantage of the superior soft tissue contrast they exhibit. However, spatial dose delivery accuracy may be deteriorated due to geometric distortions which are partly attributed to static magnetic field inhomogeneity and patient/object-induced chemical shift and susceptibility related artifacts, known as sequence-dependent distortions. Several post-imaging sequence-dependent distortion correction schemes have been proposed which mainly employ the reversal of read gradient polarity. The scope of this work is to review, evaluate and compare the efficacy of two proposed correction approaches. A specially designed phantom which incorporates 947 control points (CPs) for distortion detection was utilized. The phantom was MR scanned at 1.5T using the head coil and the clinically employed pulse sequence for SRS treatment planning. An additional scan was performed with identical imaging parameters except for reversal of read gradient polarity. In-house MATLAB routines were developed for implementation of the signal integration and average-image distortion correction techniques. The mean CP locations of the two MR scans were regarded as the reference CP distribution. Residual distortion was assessed by comparing the corrected CP locations with corresponding reference positions. Mean absolute distortion on frequency encoding direction was reduced from 0.34mm (original images) to 0.15mm and 0.14mm following application of signal integration and average-image methods, respectively. However, a maximum residual distortion of 0.7mm was still observed for both techniques. The signal integration method relies on the accuracy of edge detection and requires 3-4 hours of post-imaging computational time. The average-image technique is a more efficient (processing time of the order of seconds) and easier to implement method to improve geometric accuracy in such

Message valence, familiarity, sex, and personality effects on the perceptual distortion of height.

Science.gov (United States)

Hensley, W E; Angoli, M

1980-03-01

The perceptual distortion of height was examined in a group of American male and female college student volunteers (n = 139). A message which announced either good or bad news was delivered by a familiar or unfamiliar person who was either male or female. After hearing the message, the students were asked to estimate the height of the communicator. Additionally, the variables of self-esteem and independence of judgment were measured. Results indicated that familiarity with the message source (p less than .0025) as well as sex of the communicator (p less than .024) were predictors of the perceptual distortion of height, but message valence was not. Neither self-esteem nor independence of judgment was functionally related to the proclivity to distort the heights of the communicators.

The right view from the wrong location: depth perception in stereoscopic multi-user virtual environments.

Science.gov (United States)

Pollock, Brice; Burton, Melissa; Kelly, Jonathan W; Gilbert, Stephen; Winer, Eliot

2012-04-01

Stereoscopic depth cues improve depth perception and increase immersion within virtual environments (VEs). However, improper display of these cues can distort perceived distances and directions. Consider a multi-user VE, where all users view identical stereoscopic images regardless of physical location. In this scenario, cues are typically customized for one "leader" equipped with a head-tracking device. This user stands at the center of projection (CoP) and all other users ("followers") view the scene from other locations and receive improper depth cues. This paper examines perceived depth distortion when viewing stereoscopic VEs from follower perspectives and the impact of these distortions on collaborative spatial judgments. Pairs of participants made collaborative depth judgments of virtual shapes viewed from the CoP or after displacement forward or backward. Forward and backward displacement caused perceived depth compression and expansion, respectively, with greater compression than expansion. Furthermore, distortion was less than predicted by a ray-intersection model of stereo geometry. Collaboration times were significantly longer when participants stood at different locations compared to the same location, and increased with greater perceived depth discrepancy between the two viewing locations. These findings advance our understanding of spatial distortions in multi-user VEs, and suggest a strategy for reducing distortion.

The distortion of social identity structure as a result of social exclusion

OpenAIRE

Suvorova I.Yu.

2016-01-01

The article describes the mechanism of human’s interaction with social system through the analysis of its distortion as a result of social exclusion. It was assumed that the impossibility to satisfy basic social needs destroys symbolic links between an individual and a social system. It causes the distortion of the structure of social identity and control over social reality. Third year students of Ecological faculty of People’s Friendship University of Rus- sia participated in the experiment...

Amplitude and phase of distortion product otoacoustic emissions in the guinea pig in an (f1,f2) area study

Science.gov (United States)

Schneider, Sandra; Prijs, Vera F.; Schoonhoven, Ruurd

2003-06-01

Lower sideband distortion product otoacoustic emissions (DPOAEs), measured in the ear canal upon stimulation with two continuous pure tones, are the result of interfering contributions from two different mechanisms, the nonlinear distortion component and the linear reflection component. The two contributors have been shown to have a different amplitude and, in particular, a different phase behavior as a function of the stimulus frequencies. The dominance of either component was investigated in an extensive (f1,f2) area study of DPOAE amplitude and phase in the guinea pig, which allows for both qualitative and quantitative analysis of isophase contours. Making a minimum of additional assumptions, simple relations between the direction of constant phase in the (f1,f2) plane and the group delays in f1-sweep, f2-sweep, and fixed f2/f1 paradigms can be derived, both for distortion (wave-fixed) and reflection (place-fixed) components. The experimental data indicate the presence of both components in the lower sideband DPOAEs, with the reflection component as the dominant contributor for low f2/f1 ratios and the distortion component for intermediate ratios. At high ratios the behavior cannot be explained by dominance of either component.

Anisotropic magnification distortion of the 3D galaxy correlation. I. Real space

International Nuclear Information System (INIS)

Hui, Lam; LoVerde, Marilena; Gaztanaga, Enrique

2007-01-01

It has long been known that gravitational lensing, primarily via magnification bias, modifies the observed galaxy (or quasar) clustering. Such discussions have largely focused on the 2D angular correlation function. Here and in paper II [L. Hui, E. Gaztanaga, and M. LoVerde, arXiv:0710.4191] we explore how magnification bias distorts the 3D correlation function and power spectrum, as first considered by Matsubara [Astrophys. J. Lett. 537, L77 (2000).]. The interesting point is that the distortion is anisotropic. Magnification bias in general preferentially enhances the observed correlation in the line-of-sight (LOS) orientation, especially on large scales. For instance, at a LOS separation of ∼100 Mpc/h, where the intrinsic galaxy-galaxy correlation is rather weak, the observed correlation can be enhanced by lensing by a factor of a few, even at a modest redshift of z∼0.35. This effect presents an interesting opportunity as well as a challenge. The opportunity: this lensing anisotropy is distinctive, making it possible to separately measure the galaxy-galaxy, galaxy-magnification, and magnification-magnification correlations, without measuring galaxy shapes. The anisotropy is distinguishable from the well-known distortion due to peculiar motions, as will be discussed in paper II. The challenge: the magnification distortion of the galaxy correlation must be accounted for in interpreting data as precision improves. For instance, the ∼100 Mpc/h baryon acoustic oscillation scale in the correlation function is shifted by up to ∼3% in the LOS orientation, and up to ∼0.6% in the monopole, depending on the galaxy bias, redshift, and number count slope. The corresponding shifts in the inferred Hubble parameter and angular diameter distance, if ignored, could significantly bias measurements of the dark energy equation of state. Lastly, magnification distortion offers a plausible explanation for the well-known excess correlations seen in pencil beam surveys

A novel frame-level constant-distortion bit allocation for smooth H.264/AVC video quality

Science.gov (United States)

Liu, Li; Zhuang, Xinhua

2009-01-01

It is known that quality fluctuation has a major negative effect on visual perception. In previous work, we introduced a constant-distortion bit allocation method [1] for H.263+ encoder. However, the method in [1] can not be adapted to the newest H.264/AVC encoder directly as the well-known chicken-egg dilemma resulted from the rate-distortion optimization (RDO) decision process. To solve this problem, we propose a new two stage constant-distortion bit allocation (CDBA) algorithm with enhanced rate control for H.264/AVC encoder. In stage-1, the algorithm performs RD optimization process with a constant quantization QP. Based on prediction residual signals from stage-1 and target distortion for smooth video quality purpose, the frame-level bit target is allocated by using a close-form approximations of ratedistortion relationship similar to [1], and a fast stage-2 encoding process is performed with enhanced basic unit rate control. Experimental results show that, compared with original rate control algorithm provided by H.264/AVC reference software JM12.1, the proposed constant-distortion frame-level bit allocation scheme reduces quality fluctuation and delivers much smoother PSNR on all testing sequences.

Reduce blurring and distortion in a projection type virtual image display using integrated small optics

Science.gov (United States)

Hasegawa, Tatsuya; Yendo, Tomohiro

2015-03-01

Head Up Display (HUD) is being applied to automobile. HUD displays information as far virtual image on the windshield. Existing HUD usually displays planar information. If the image corresponding to scenery on the road like Augmented Reality (AR) is displayed on the HUD, driver can efficiently get the information. To actualize this, HUD covering large viewing field is needed. However existing HUD cannot cover large viewing field. Therefore we have proposed system consisting of projector and many small diameter convex lenses. However observed virtual image has blurring and distortion . In this paper, we propose two methods to reduce blurring and distortion of images. First, to reduce blurring of images, distance between each of screen and lens comprised in lens array is adjusted. We inferred from the more distant the lens from center of the array is more blurred that the cause of blurring is curvature of field of lens in the array. Second, to avoid distortion of images, each lens in the array is curved spherically. We inferred from the more distant the lens from center of the array is more distorted that the cause of distortion is incident angle of ray. We confirmed effectiveness of both methods.

Galileo: The Added Value for Integrity in Harsh Environments

Directory of Open Access Journals (Sweden)

Daniele Borio

2016-01-01

Full Text Available A global navigation satellite system (GNSS-based navigation is a challenging task in a signal-degraded environments where GNSS signals are distorted by multipath and attenuated by fading effects: the navigation solution may be inaccurate or unavailable. A possible approach to improve accuracy and availability is the joint use of measurements from different GNSSs and quality check algorithms; this approach is investigated here using live GPS and Galileo signals. A modified receiver autonomous integrity monitoring (RAIM algorithm, including geometry and separability checks, is proposed to detect and exclude erroneous measurements: the multi-constellation approach provides redundant measurements, and RAIM exploits them to exclude distorted observations. The synergy between combined GPS/Galileo navigation and RAIM is analyzed using live data; the performance is compared to the accuracy and availability of a GPS-only solution. The tests performed demonstrate that the methods developed are effective techniques for GNSS-based navigation in signal-degraded environments. The joint use of the multi-constellation approach and of modified RAIM algorithms improves the performance of the navigation system in terms of both accuracy and availability.

Galileo: The Added Value for Integrity in Harsh Environments.

Science.gov (United States)

Borio, Daniele; Gioia, Ciro

2016-01-16

A global navigation satellite system (GNSS)-based navigation is a challenging task in a signal-degraded environments where GNSS signals are distorted by multipath and attenuated by fading effects: the navigation solution may be inaccurate or unavailable. A possible approach to improve accuracy and availability is the joint use of measurements from different GNSSs and quality check algorithms; this approach is investigated here using live GPS and Galileo signals. A modified receiver autonomous integrity monitoring (RAIM) algorithm, including geometry and separability checks, is proposed to detect and exclude erroneous measurements: the multi-constellation approach provides redundant measurements, and RAIM exploits them to exclude distorted observations. The synergy between combined GPS/Galileo navigation and RAIM is analyzed using live data; the performance is compared to the accuracy and availability of a GPS-only solution. The tests performed demonstrate that the methods developed are effective techniques for GNSS-based navigation in signal-degraded environments. The joint use of the multi-constellation approach and of modified RAIM algorithms improves the performance of the navigation system in terms of both accuracy and availability.

Journal Afrika Statistika ISSN 0852-0305 Distortion risk measures ...

African Journals Online (AJOL)

la somme et sur la structure de dépendance des risques, représentée par une copule. ... Key words: Coherence; Dependence structure; Distortion function; Risk measure; Risk theory; insurance; Wang ..... Weighted risk capital allocations.

A multipoint flux mixed finite element method on distorted quadrilaterals and hexahedra

KAUST Repository

Wheeler, Mary

2011-11-06

In this paper, we develop a new mixed finite element method for elliptic problems on general quadrilateral and hexahedral grids that reduces to a cell-centered finite difference scheme. A special non-symmetric quadrature rule is employed that yields a positive definite cell-centered system for the pressure by eliminating local velocities. The method is shown to be accurate on highly distorted rough quadrilateral and hexahedral grids, including hexahedra with non-planar faces. Theoretical and numerical results indicate first-order convergence for the pressure and face fluxes. © 2011 Springer-Verlag.

Critical operations capabilities in a high cost environment: a multiple case study

Science.gov (United States)

Sansone, C.; Hilletofth, P.; Eriksson, D.

2018-04-01

Operations capabilities have been a popular research area for many years and several frameworks have been proposed in the literature. The current frameworks do not take specific contexts into consideration, for instance a high cost environment. This research gap is of particular interest since a manufacturing relocation process has been ongoing the last decades, leading to a huge amount of manufacturing being moved from high to low cost environments. The purpose of this study is to identify critical operations capabilities in a high cost environment. The two research questions were: What are the critical operations capabilities dimensions in a high cost environment? What are the critical operations capabilities in a high cost environment? A multiple case study was conducted and three Swedish manufacturing firms were selected. The study was based on the investigation of an existing framework of operations capabilities. The main dimensions of operations capabilities included in the framework were: cost, quality, delivery, flexibility, service, innovation and environment. Each of the dimensions included two or more operations capabilities. The findings confirmed the validity of the framework and its usefulness in a high cost environment and a new operations capability was revealed (employee flexibility).

Experimental dead-time distortions of Poisson processes

International Nuclear Information System (INIS)

Faraci, G.; Pennisi, A.R.; Consiglio Nazionale delle Ricerche, Catania

1983-01-01

In order to check the distortions, introduced by a non-extended dead time on the Poisson statistics, accurate experiments have been made in single channel counting. At a given measuring time, the dependence on the choice of the time origin and on the width of the dead time has been verified. An excellent agreement has been found between the theoretical expressions and the experimental curves. (orig.)

Correction of MRI-induced geometric distortions in whole-body small animal PET-MRI

International Nuclear Information System (INIS)

Frohwein, Lynn J.; Schäfers, Klaus P.; Hoerr, Verena; Faber, Cornelius

2015-01-01

Purpose: The fusion of positron emission tomography (PET) and magnetic resonance imaging (MRI) data can be a challenging task in whole-body PET-MRI. The quality of the registration between these two modalities in large field-of-views (FOV) is often degraded by geometric distortions of the MRI data. The distortions at the edges of large FOVs mainly originate from MRI gradient nonlinearities. This work describes a method to measure and correct for these kind of geometric distortions in small animal MRI scanners to improve the registration accuracy of PET and MRI data. Methods: The authors have developed a geometric phantom which allows the measurement of geometric distortions in all spatial axes via control points. These control points are detected semiautomatically in both PET and MRI data with a subpixel accuracy. The spatial transformation between PET and MRI data is determined with these control points via 3D thin-plate splines (3D TPS). The transformation derived from the 3D TPS is finally applied to real MRI mouse data, which were acquired with the same scan parameters used in the phantom data acquisitions. Additionally, the influence of the phantom material on the homogeneity of the magnetic field is determined via field mapping. Results: The spatial shift according to the magnetic field homogeneity caused by the phantom material was determined to a mean of 0.1 mm. The results of the correction show that distortion with a maximum error of 4 mm could be reduced to less than 1 mm with the proposed correction method. Furthermore, the control point-based registration of PET and MRI data showed improved congruence after correction. Conclusions: The developed phantom has been shown to have no considerable negative effect on the homogeneity of the magnetic field. The proposed method yields an appropriate correction of the measured MRI distortion and is able to improve the PET and MRI registration. Furthermore, the method is applicable to whole-body small animal

Correction of MRI-induced geometric distortions in whole-body small animal PET-MRI

Energy Technology Data Exchange (ETDEWEB)

Frohwein, Lynn J., E-mail: frohwein@uni-muenster.de; Schäfers, Klaus P. [European Institute for Molecular Imaging, University of Münster, Münster 48149 (Germany); Hoerr, Verena; Faber, Cornelius [Department of Clinical Radiology, University Hospital of Münster, Münster 48149 (Germany)

2015-07-15

Purpose: The fusion of positron emission tomography (PET) and magnetic resonance imaging (MRI) data can be a challenging task in whole-body PET-MRI. The quality of the registration between these two modalities in large field-of-views (FOV) is often degraded by geometric distortions of the MRI data. The distortions at the edges of large FOVs mainly originate from MRI gradient nonlinearities. This work describes a method to measure and correct for these kind of geometric distortions in small animal MRI scanners to improve the registration accuracy of PET and MRI data. Methods: The authors have developed a geometric phantom which allows the measurement of geometric distortions in all spatial axes via control points. These control points are detected semiautomatically in both PET and MRI data with a subpixel accuracy. The spatial transformation between PET and MRI data is determined with these control points via 3D thin-plate splines (3D TPS). The transformation derived from the 3D TPS is finally applied to real MRI mouse data, which were acquired with the same scan parameters used in the phantom data acquisitions. Additionally, the influence of the phantom material on the homogeneity of the magnetic field is determined via field mapping. Results: The spatial shift according to the magnetic field homogeneity caused by the phantom material was determined to a mean of 0.1 mm. The results of the correction show that distortion with a maximum error of 4 mm could be reduced to less than 1 mm with the proposed correction method. Furthermore, the control point-based registration of PET and MRI data showed improved congruence after correction. Conclusions: The developed phantom has been shown to have no considerable negative effect on the homogeneity of the magnetic field. The proposed method yields an appropriate correction of the measured MRI distortion and is able to improve the PET and MRI registration. Furthermore, the method is applicable to whole-body small animal

Source Coding in Networks with Covariance Distortion Constraints

DEFF Research Database (Denmark)

Zahedi, Adel; Østergaard, Jan; Jensen, Søren Holdt

2016-01-01

results to a joint source coding and denoising problem. We consider a network with a centralized topology and a given weighted sum-rate constraint, where the received signals at the center are to be fused to maximize the output SNR while enforcing no linear distortion. We show that one can design...

Study of Local and Distortional Stability of Thin-Walled Structures

Directory of Open Access Journals (Sweden)

Imene Mahi

2018-01-01

Full Text Available Thin-walled structures have an increasingly large and growing field of application in the engineering sector, the goal behind using this type of structure is efficiency in terms of resistance and cost, however the stability of its components (the thin walls remains the first aspect of the behavior, and a primordial factor in the design process. The hot rolled sections are known by a consequent post-buckling reserve, cold-formed steel sections which are thin-walled elements also benefit, in this case, it seems essential to take into account the favorable effects of this reserve in to the verification procedure of the resistance with respect to the three modes of failures of this type of structure. The design method that takes into account this reserve of resistance is inevitably the effective width method. The direct strength method has been developed to improve the speed and efficiency of the design of thin-walled profiles. The latter mainly uses the buckling loads (for Local, Distortional and Global mode obtained from a numerical analysis and the resistance curves calibrated experimentally to predict the ultimate load of the profile. Among those, the behavior of a set of Cshaped profiles (highly industrialized is studied, this type of section is assumed to be very prone to modes of local and distortional instability. The outcome of this investigation revealed very relevant conclusions both scientifically and practically.

Correction for polychromatic X-ray image distortion in computer tomography images

International Nuclear Information System (INIS)

1979-01-01

A method and apparatus are described which correct the polychromatic distortion of CT images that is produced by the non-linear interaction of body constituents with a polychromatic X-ray beam. A CT image is processed to estimate the proportion of the attenuation coefficients of the constituents in each pixel element. A multiplicity of projections for each constituent are generated from the original image and are combined utilizing a multidimensional polynomial which approximates the non-linear interaction involved. An error image is then generated from the combined projections and is subtracted from the original image to correct for the polychromatic distortion. (Auth.)

Use of Roche coordinates in the problems of small oscillations of tidally-distorted stellar models. II

International Nuclear Information System (INIS)

Mohan, C.; Singh, V.P.

1979-01-01

Kopal's method of Roche coordinates used by the authors in an earlier paper (Mohan and Singh, 1978) to study the problems of small oscillations of tidally-distorted stars has been extended further to take into account the effect of second-order terms in tidal distortion. The results show that the effect of including terms of second order of smallness in tidal distortion in the metric coefficients of the Roche coordinates of tidally distroted stars is quite significant, especially in case of stars with extended envelopes and (or) larger values of the companion star producing tidal distortion. Some of the models which were earlier found stable against small perturbations now become dynamically unstable with the inclusion of the terms of second order of smallness in tidal effects. (Auth.)

Vector neural net identifying many strongly distorted and correlated patterns

Science.gov (United States)

Kryzhanovsky, Boris V.; Mikaelian, Andrei L.; Fonarev, Anatoly B.

2005-01-01

We suggest an effective and simple algorithm providing a polynomial storage capacity of a network of the form M ~ N2s+1, where N is the dimension of the stored binary patterns. In this problem the value of the free parameter s is restricted by the inequalities N >> slnN >= 1. The algorithm allows us to identify a large number of highly distorted similar patterns. The negative influence of correlations of the patterns is suppressed by choosing a sufficiently large value of the parameter s. We show the efficiency of the algorithm by the example of a perceptron identifier, but it also can be used to increase the storage capacity of full connected systems of associative memory.

Beyond y and μ: the shape of the CMB spectral distortions in the intermediate epoch, 1.5 × 104∼5

International Nuclear Information System (INIS)

Khatri, Rishi; Sunyaev, Rashid A.

2012-01-01

We calculate numerical solutions and analytic approximations for the intermediate-type spectral distortions. Detection of a μ-type distortion (saturated comptonization) in the CMB will constrain the time of energy injection to be at a redshift 2 × 10 6 ∼>z∼>2 × 10 5 , while a detection of a y-type distortion (minimal comptonization) will mean that there was heating of CMB at redshift z∼ 4 . We point out that the partially comptonized spectral distortions, generated in the redshift range 1.5 × 10 4 ∼ 5 , are much richer in information than the pure y and μ-type distortions. The spectrum created during this period is intermediate between y and μ-type distortions and depends sensitively on the redshift of energy injection. These intermediate-type distortions cannot be mimicked by a mixture of y and μ-type distortions at all frequencies and vice versa. The measurement of these intermediate-type CMB spectral distortions has the possibility to constrain precisely not only the amount of energy release in the early Universe but also the mechanism, for example, particle annihilation and Silk damping can be distinguished from particle decay. The intermediate-type distortion templates and software code using these templates to calculate the CMB spectral distortions for user-defined energy injection rate is made publicly available

Mothers' Depressive State "Distorts" the Ratings of Depression They Give for Their Sons with an Autism Spectrum Disorder

Science.gov (United States)

Bitsika, Vicki; Sharpley, Christopher F.

2016-01-01

Depression is highly prevalent in children who have an Autism Spectrum Disorder (ASD), potentially confounding accurate diagnosis and treatment planning. Although information about the depressive status of a child is often collected from parents, there is evidence of distortion in parental assessments of their offspring's depression. This…

Influences of flow loss and inlet distortions from radial inlets on the performances of centrifugal compressor stages

International Nuclear Information System (INIS)

Han, Feng Hui; Mao, Yi Jun; Tan, Ji Jian

2016-01-01

Radial inlets are typical upstream components of multistage centrifugal compressors. Unlike axial inlets, radial inlets generate additional flow loss and introduce flow distortions at impeller inlets. Such distortions negatively affect the aerodynamic performance of compressor stages. In this study, industrial centrifugal compressor stages with different radial inlets are investigated via numerical simulations. Two reference models were built, simulated, and compared with each original compressor stage to analyze the respective and coupling influences of flow loss and inlet distortions caused by radial inlets on the performances of the compressor stage and downstream components. Flow loss and inlet distortions are validated as the main factors through which radial inlets negatively affect compressor performance. Results indicate that flow loss inside radial inlets decreases the performance of the whole compressor stage but exerts minimal effect on downstream components. By contrast, inlet distortions induced by radial inlets negatively influence the performance of the whole compressor stage and exert significant effects on downstream components. Therefore, when optimizing radial inlets, the reduction of inlet distortions might be more effective than the reduction of flow loss. This research provides references and suggestions for the design and improvement of radial inlets

Influences of flow loss and inlet distortions from radial inlets on the performances of centrifugal compressor stages

Energy Technology Data Exchange (ETDEWEB)

Han, Feng Hui; Mao, Yi Jun [School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an (China); Tan, Ji Jian [Dept. of Research and Development, Shenyang Blower Works Group Co., Ltd., Shenyang (China)

2016-11-15

Radial inlets are typical upstream components of multistage centrifugal compressors. Unlike axial inlets, radial inlets generate additional flow loss and introduce flow distortions at impeller inlets. Such distortions negatively affect the aerodynamic performance of compressor stages. In this study, industrial centrifugal compressor stages with different radial inlets are investigated via numerical simulations. Two reference models were built, simulated, and compared with each original compressor stage to analyze the respective and coupling influences of flow loss and inlet distortions caused by radial inlets on the performances of the compressor stage and downstream components. Flow loss and inlet distortions are validated as the main factors through which radial inlets negatively affect compressor performance. Results indicate that flow loss inside radial inlets decreases the performance of the whole compressor stage but exerts minimal effect on downstream components. By contrast, inlet distortions induced by radial inlets negatively influence the performance of the whole compressor stage and exert significant effects on downstream components. Therefore, when optimizing radial inlets, the reduction of inlet distortions might be more effective than the reduction of flow loss. This research provides references and suggestions for the design and improvement of radial inlets.

The Role of Emotion Regulation in Reducing Emotional Distortions of Duration Perception

Directory of Open Access Journals (Sweden)

Yu Tian

2018-03-01

Full Text Available Emotional events, especially negative ones, are consistently reported to last longer than neutral events. Previous studies suggested that this distortion of duration perception is linked to arousal and attention bias in response to emotional events. Reappraisal and suppression, arguably the most effective strategies for emotion regulation, have been demonstrated to decrease such arousal and attention bias. The present study investigated whether reappraisal and suppression can reduce emotional distortions of duration perception. Seventy-eight Chinese undergraduates were recruited as paid participants and randomly assigned to nonregulation, reappraisal, and suppression groups. Before they performed a temporal bisection task involving presentation of emotional pictures for different durations, the groups were each given one of three different sets of instructions requiring them to passively perceive, reappraise, or suppress the emotions of the pictures. The results indicated that the distortion of duration perception occurred only in the nonregulation group, suggesting that it can be effectively reduced by reappraisal and suppression.

[Distortion and vertical fracture of the root: effect produced by condenser design].

Science.gov (United States)

Dang, D A; Walton, R E

1990-01-01

The incidence of vertical root fractures and the amount of root distortion created during lateral condensation of gutta-percha with either D11 spreaders or B-finger pluggers were evaluated in vitro. Fifty-five extracted human, single-rooted teeth were instrumented using the step-back flare technique. Ten teeth served as positive controls (obturation to the point of fracture) and five teeth as negative controls (prepared but not obtured). Strain gauges were attached to the root surfaces. In the experimental group, 20 teeth were obturated using a D11 spreader and 20 with a B-finger plugger. Recordings were made of root distortion (expansion) created during obturation. Then, after sectioning the teeth, root surfaces of obturated samples were examined for fractures under the scanning electron microscope. Only the more tapered spreader, the D11, produces vertical root fractures, although very few in number. Also, the D11 spreader caused greater root distortion than did the B-finger plugger.

Analysis of reforming process of large distorted ring in final enlarging forging

International Nuclear Information System (INIS)

Miyazawa, Takeshi; Murai, Etsuo

2002-01-01

In the construction of reactors or pressure vessels for oil chemical plants and nuclear power stations, mono block open-die forging rings are often utilized. Generally, a large forged ring is manufactured by means of enlarging forging with reductions of the wall thickness. During the enlarging process the circular ring is often distorted and becomes an ellipse in shape. However the shape control of the ring is a complicated work. This phenomenon makes the matter still worse in forging of larger rings. In order to make precision forging of large rings, we have developed the forging method using a v-shape anvil. The v-shape anvil is geometrically adjusted to fit the distorted ring in the final circle and reform automatically the shape of the ring during enlarging forging. This paper has analyzed the reforming process of distorted ring by computer program based on F.E.M. and examined the effect on the precision of ring forging. (author)

Space mappings with bounded distortion

CERN Document Server

Reshetnyak, Yu G

1989-01-01

This book is intended for researchers and students concerned with questions in analysis and function theory. The author provides an exposition of the main results obtained in recent years by Soviet and other mathematicians in the theory of mappings with bounded distortion, an active direction in contemporary mathematics. The mathematical tools presented can be applied to a broad spectrum of problems that go beyond the context of the main topic of investigation. For a number of questions in the theory of partial differential equations and the theory of functions with generalized derivatives, this is the first time they have appeared in an internationally distributed monograph.

Distortion effects in pion-induced knock-out reactions

International Nuclear Information System (INIS)

Jain, B.K.

The cross-section for (π + ,π + p) reaction on 12 C is calculated in DWIA at 100 and 180 MeV incident energy. The effect of pion distortion is found to be strong. Around 180 MeV the effect is strongly absorptive while around 10O MeV it is mainly dispersive. (auth.)

The effect of band Jahn-Teller distortion on the magnetoresistivity of manganites: a model study

Energy Technology Data Exchange (ETDEWEB)

Rout, G C [Condensed Matter Physics Group, P G Department of Applied Physics and Ballistics, F M University, Balasore 756 019 (India); Panda, Saswati [Trident Academy of Technology, F2/A, Chandaka Industrial Estate, Bhubaneswar 751 024 (India); Behera, S N, E-mail: gcr@iopb.res.in, E-mail: saswatip7@gmail.com [National Institute of Science and Technology, Palur Hills, Berhampur 761 008 (India)

2011-10-05

We present a model study of magnetoresistance through the interplay of magnetisation, structural distortion and external magnetic field for the manganite systems. The manganite system is described by the Hamiltonian which consists of the s-d type double exchange interaction, Heisenberg spin-spin interaction among the core electrons, and the static and dynamic band Jahn-Teller (JT) interaction in the e{sub g} band. The relaxation time of the e{sub g} electron is found from the imaginary part of the Green's function using the total Hamiltonian consisting of the interactions due to the electron and phonon. The calculated resistivity exhibits a peak in the pure JT distorted insulating phase separating the low temperature metallic ferromagnetic phase and the high temperature paramagnetic phase. The resistivity is suppressed with the increase of the external magnetic field. The e{sub g} electron band splitting and its effect on magnetoresistivity is reported here. (paper)

Decision making, cognitive distortions and emotional distress: A comparison between pathological gamblers and healthy controls.

Science.gov (United States)

Ciccarelli, Maria; Griffiths, Mark D; Nigro, Giovanna; Cosenza, Marina

2017-03-01

The etiology of problem gambling is multifaceted and complex. Among others factors, poor decision making, cognitive distortions (i.e., irrational beliefs about gambling), and emotional factors (e.g., negative mood states) appear to be among the most important factors in the development and maintenance of problem gambling. Although empirical evidence has suggested that cognitive distortions facilitate gambling and negative emotions are associated with gambling, the interplay between cognitive distortions, emotional states, and decision making in gambling remains unexplored. Pathological gamblers (N = 54) and healthy controls (N = 54) completed the South Oaks Gambling Screen (SOGS), the Iowa Gambling Task (IGT), the Gambling Related Cognitions Scale (GRCS), and the Depression Anxiety Stress Scale (DASS-21). Compared to healthy controls, pathological gamblers showed poorer decision making and reported higher scores on measures assessing cognitive distortions and emotional distress. All measures were positively associated with gambling severity. A significant negative correlation between decision making and cognitive distortions was also observed. No associations were found between poor decision making and emotional distress. Logistic regression analysis indicated that cognitive distortions, emotional distress, and poor decision making were significant predictors of problem gambling. The use of self-report measures and the absence of female participants limit the generalizability of the reported findings. The present study is the first to demonstrate the mutual influence between irrational beliefs and poor decision making, as well as the role of cognitive bias, emotional distress, and poor decision making in gambling disorder. Copyright © 2016 Elsevier Ltd. All rights reserved.

A search for transmission ratio distortions in offspring from crosses ...

Indian Academy of Sciences (India)

differential embryonic mortality, nondisjunction and gene conversion that are rather irregular forms of ... Keywords. transmission ratio distortion; meiotic drive; inbred mice. ..... Sapienza 2000 Heritability of the maternal meiotic drive system.

Body Dysmorphic Disorder: Easing the Distress of Distortion.

Science.gov (United States)

Fore, Cynthia M.

People who suffer from body dysmorphic disorder believe that their body is defected and that this defect makes them ugly. Their distorted body image can be precipitated by many internal and external factors and as a result of their imagined defect, these normal-appearing individuals exhibit self-defeating behaviors. The disorder can lead to the…

Effects of Cognitive Distortions on the Link Between Dating Violence Exposure and Substance Problems in Clinically Hospitalized Youth.

Science.gov (United States)

Miller, Adam Bryant; Williams, Caitlin; Day, Catherine; Esposito-Smythers, Christianne

2017-06-01

The purpose of the present study was to examine whether cognitive distortions (e.g., cognitive errors; negative views of self, world, and future) influence the association between dating violence and problematic substance use behaviors in a sample of psychiatrically hospitalized adolescents. Participants included 155 adolescents, aged 13-17 years, who had initiated dating. Adolescents completed measures of dating violence, substance-related problems (alcohol and marijuana), and cognitive distortions. Logistic regressions were conducted to examine the direct and interactive effects of dating violence exposure and cognitive distortions on likelihood of recent problematic substance use. Results suggested a main effect of dating violence on problematic alcohol and other drug use as well as an interactive effect of dating violence and cognitive distortions. Specifically, the relationship between dating violence and odds of substance-related problems was higher among those with greater (vs. fewer) cognitive distortions. Study results suggest the need for careful screening of cognitive distortions among adolescent dating violence victims, particularly those in mental health treatment. © 2016 Wiley Periodicals, Inc.

Extracting foreground-obscured μ-distortion anisotropies to constrain primordial non-Gaussianity

Science.gov (United States)

Remazeilles, M.; Chluba, J.

2018-04-01

Correlations between cosmic microwave background (CMB) temperature, polarization and spectral distortion anisotropies can be used as a probe of primordial non-Gaussianity. Here, we perform a reconstruction of μ-distortion anisotropies in the presence of Galactic and extragalactic foregrounds, applying the so-called Constrained ILC component separation method to simulations of proposed CMB space missions (PIXIE, LiteBIRD, CORE, PICO). Our sky simulations include Galactic dust, Galactic synchrotron, Galactic free-free, thermal Sunyaev-Zeldovich effect, as well as primary CMB temperature and μ-distortion anisotropies, the latter being added as correlated field. The Constrained ILC method allows us to null the CMB temperature anisotropies in the reconstructed μ-map (and vice versa), in addition to mitigating the contaminations from astrophysical foregrounds and instrumental noise. We compute the cross-power spectrum between the reconstructed (CMB-free) μ-distortion map and the (μ-free) CMB temperature map, after foreground removal and component separation. Since the cross-power spectrum is proportional to the primordial non-Gaussianity parameter, fNL, on scales k˜eq 740 Mpc^{-1}, this allows us to derive fNL-detection limits for the aforementioned future CMB experiments. Our analysis shows that foregrounds degrade the theoretical detection limits (based mostly on instrumental noise) by more than one order of magnitude, with PICO standing the best chance at placing upper limits on scale-dependent non-Gaussianity. We also discuss the dependence of the constraints on the channel sensitivities and chosen bands. Like for B-mode polarization measurements, extended coverage at frequencies ν ≲ 40 GHz and ν ≳ 400 GHz provides more leverage than increased channel sensitivity.

The UV Plasmonic Behavior of Distorted Rhodium Nanocubes

Directory of Open Access Journals (Sweden)

Yael Gutiérrez

2017-12-01

Full Text Available For applications of surface-enhanced spectroscopy and photocatalysis, the ultraviolet (UV plasmonic behavior and charge distribution within rhodium nanocubes is explored by a detailed numerical analysis. The strongest plasmonic hot-spots and charge concentrations are located at the corners and edges of the nanocubes, exactly where they are the most spectroscopically and catalytically active. Because intense catalytic activity at corners and edges will reshape these nanoparticles, distortions of the cubical shape, including surface concavity, surface convexity, and rounded corners and edges, are also explored to quantify how significantly these distortions deteriorate their plasmonic and photocatalytic properties. The fact that the highest fields and highest carrier concentrations occur in the corners and edges of Rh nanocubes (NCs confirms their tremendous potential for plasmon-enhanced spectroscopy and catalysis. It is shown that this opportunity is fortuitously enhanced by the fact that even higher field and charge concentrations reside at the interface between the metal nanoparticle and a dielectric or semiconductor support, precisely where the most chemically active sites are located.

Compressed sensing techniques for receiver based post-compensation of transmitter's nonlinear distortions in OFDM systems

KAUST Repository

Owodunni, Damilola S.

2014-04-01

In this paper, compressed sensing techniques are proposed to linearize commercial power amplifiers driven by orthogonal frequency division multiplexing signals. The nonlinear distortion is considered as a sparse phenomenon in the time-domain, and three compressed sensing based algorithms are presented to estimate and compensate for these distortions at the receiver using a few and, at times, even no frequency-domain free carriers (i.e. pilot carriers). The first technique is a conventional compressed sensing approach, while the second incorporates a priori information about the distortions to enhance the estimation. Finally, the third technique involves an iterative data-aided algorithm that does not require any pilot carriers and hence allows the system to work at maximum bandwidth efficiency. The performances of all the proposed techniques are evaluated on a commercial power amplifier and compared. The error vector magnitude and symbol error rate results show the ability of compressed sensing to compensate for the amplifier\\'s nonlinear distortions. © 2013 Elsevier B.V.

Medical-grade Sterilizable Target for Fluid-immersed Fetoscope Optical Distortion Calibration.

Science.gov (United States)

Nikitichev, Daniil I; Shakir, Dzhoshkun I; Chadebecq, François; Tella, Marcel; Deprest, Jan; Stoyanov, Danail; Ourselin, Sébastien; Vercauteren, Tom

2017-02-23

We have developed a calibration target for use with fluid-immersed endoscopes within the context of the GIFT-Surg (Guided Instrumentation for Fetal Therapy and Surgery) project. One of the aims of this project is to engineer novel, real-time image processing methods for intra-operative use in the treatment of congenital birth defects, such as spina bifida and the twin-to-twin transfusion syndrome. The developed target allows for the sterility-preserving optical distortion calibration of endoscopes within a few minutes. Good optical distortion calibration and compensation are important for mitigating undesirable effects like radial distortions, which not only hamper accurate imaging using existing endoscopic technology during fetal surgery, but also make acquired images less suitable for potentially very useful image computing applications, like real-time mosaicing. In this paper proposes a novel fabrication method to create an affordable, sterilizable calibration target suitable for use in a clinical setup. This method involves etching a calibration pattern by laser cutting a sandblasted stainless steel sheet. This target was validated using the camera calibration module provided by OpenCV, a state-of-the-art software library popular in the computer vision community.

Effect of Rap1 binding on DNA distortion and potassium permanganate hypersensitivity.

Science.gov (United States)

Le Bihan, Yann-Vaï; Matot, Béatrice; Pietrement, Olivier; Giraud-Panis, Marie-Josèphe; Gasparini, Sylvaine; Le Cam, Eric; Gilson, Eric; Sclavi, Bianca; Miron, Simona; Le Du, Marie-Hélène

2013-03-01

Repressor activator protein 1 (Rap1) is an essential factor involved in transcription and telomere stability in the budding yeast Saccharomyces cerevisiae. Its interaction with DNA causes hypersensitivity to potassium permanganate, suggesting local DNA melting and/or distortion. In this study, various Rap1-DNA crystal forms were obtained using specifically designed crystal screens. Analysis of the DNA conformation showed that its distortion was not sufficient to explain the permanganate reactivity. However, anomalous data collected at the Mn edge using a Rap1-DNA crystal soaked in potassium permanganate solution indicated that the DNA conformation in the crystal was compatible with interaction with permanganate ions. Sequence-conservation analysis revealed that double-Myb-containing Rap1 proteins all carry a fully conserved Arg580 at a position that may favour interaction with permanganate ions, although it is not involved in the hypersensitive cytosine distortion. Permanganate reactivity assays with wild-type Rap1 and the Rap1[R580A] mutant demonstrated that Arg580 is essential for hypersensitivity. AFM experiments showed that wild-type Rap1 and the Rap1[R580A] mutant interact with DNA over 16 successive binding sites, leading to local DNA stiffening but not to accumulation of the observed local distortion. Therefore, Rap1 may cause permanganate hypersensitivity of DNA by forming a pocket between the reactive cytosine and Arg580, driving the permanganate ion towards the C5-C6 bond of the cytosine.

Quantitative studies with the gamma-camera: correction for spatial and energy distortion

International Nuclear Information System (INIS)

Soussaline, F.; Todd-Pokropek, A.E.; Raynaud, C.

1977-01-01

The gamma camera sensitivity distribution is an important source of error in quantitative studies. In addition, spatial distortion produces apparent variations in count density which degrades quantitative studies. The flood field image takes into account both effects and is influenced by the pile-up of the tail distribution. It is essential to measure separately each of these parameters. These were investigated using a point source displaced by a special scanning table with two X, Y stepping motors of 10 micron precision. The spatial distribution of the sensitivity, spatial distortion and photopeak in the field of view were measured and compared for different setting-up of the camera and PM gains. For well-tuned cameras, the sensitivity is fairly constant, while the variations appearing in the flood field image are primarily due to spatial distortion, the former more dependent than the latter on the energy window setting. This indicates why conventional flood field uniformity correction must not be applied. A correction technique to improve the results in quantitative studies has been tested using a continuously matched energy window at every point within the field. A method for correcting spatial distortion is also proposed, where, after an adequately sampled measurement of this error, a transformation can be applied to calculate the true position of events. The knowledge of the magnitude of these parameters is essential in the routine use and design of detector systems

Taking the Universe's Temperature with Spectral Distortions of the Cosmic Microwave Background.

Science.gov (United States)

Hill, J Colin; Battaglia, Nick; Chluba, Jens; Ferraro, Simone; Schaan, Emmanuel; Spergel, David N

2015-12-31

The cosmic microwave background (CMB) energy spectrum is a near-perfect blackbody. The standard model of cosmology predicts small spectral distortions to this form, but no such distortion of the sky-averaged CMB spectrum has yet been measured. We calculate the largest expected distortion, which arises from the inverse Compton scattering of CMB photons off hot, free electrons, known as the thermal Sunyaev-Zel'dovich (TSZ) effect. We show that the predicted signal is roughly one order of magnitude below the current bound from the COBE-FIRAS experiment, but it can be detected at enormous significance (≳1000σ) by the proposed Primordial Inflation Explorer (PIXIE). Although cosmic variance reduces the effective signal-to-noise ratio to 230σ, this measurement will still yield a subpercent constraint on the total thermal energy of electrons in the observable Universe. Furthermore, we show that PIXIE can detect subtle relativistic effects in the sky-averaged TSZ signal at 30σ, which directly probe moments of the optical depth-weighted intracluster medium electron temperature distribution. These effects break the degeneracy between the electron density and the temperature in the mean TSZ signal, allowing a direct inference of the mean baryon density at low redshift. Future spectral distortion probes will thus determine the global thermodynamic properties of ionized gas in the Universe with unprecedented precision. These measurements will impose a fundamental "integral constraint" on models of galaxy formation and the injection of feedback energy over cosmic time.

Disposal of high level nuclear wastes: Thermodynamic equilibrium and environment ethics

Institute of Scientific and Technical Information of China (English)

RANA Mukhtar Ahmed

2009-01-01

Contamination of soil, water or air, due to a failure of containment or disposal of high level nuclear wastes, can potentially cause serious hazards to the environment or human health. Essential elements of the environment and radioactivity dangers to it are illustrated. Issues of high level nuclear waste disposal are discussed with a focus on thermodynamic equilibrium and environment ethics. Major aspects of the issues are analyzed and described briefly to build a perception of risks involved and ethical implications. Nuclear waste containment repository should be as close as possible to thermodynamic equilibrium. A clear demonstration about safety aspects of nuclear waste management is required in gaining public and political confidence in any possible scheme of permanent disposal. Disposal of high level nuclear waste offers a spectrum of environment connected challenges and a long term future of nuclear power depends on the environment friendly solution of the problem of nuclear wastes.

Electronic properties of single-molecule junction: Effect of the molecular distortion

International Nuclear Information System (INIS)

Gao, W.; Zhao, M.; Jiang, Q.

2009-01-01

For a model system consisting of a benzenedithio (BDT) molecule sandwiched between two Au plates, the electronic properties as a function of different BDT geometry are investigated using density functional theory. The distorted BDT structures are got through stretching the electrode distance. The corresponding electronic properties, including the spatial distribution of the frontier orbits, the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital levels and density of states at the Fermi energy are determined. It reveals that the molecular distortion essentially determines electronic structures. The result should be beneficial to understand the stress-dependent or structure-dependent transport mechanism of electrons of the BDT junction.

Modifications in the rhombohedral degree of distortion and magnetic properties of Ba-doped BiFeO3 as a function of synthesis methodology

International Nuclear Information System (INIS)

Rojas-George, G.; Silva, J.; Castañeda, R.; Lardizábal, D.; Graeve, O.A.; Fuentes, L.; Reyes-Rojas, A.

2014-01-01

We present an analysis of crystallographic symmetry and the origin of the pseudo-cubic character of doped BiFeO 3 . Specifically, barium-doped bismuth ferrite, Bi 1−x Ba x FeO 3 (x = 0.05, 0.075, 0.1, 0.125), perovskite-type nanoparticles have been synthesized by implementing five modifications to the sol–gel technique (citric acid-assisted sol–gel method, ethylene glycol method, tartaric acid-assisted sol–gel method, polyvinyl alcohol–ethylene glycol method, and EDTA complexing sol–gel method) and their final pseudo-cubic character is discussed. The effect of the carboxylic groups and hydroxyl groups during synthesis is critical to obtain single phase BBFO. Fourier transform infrared spectroscopy and thermogravimetric analysis is used to study the decomposition and thermal behavior of the precursors and their relation to the final nanoparticle characteristics. X-ray diffraction analysis shows a single phase with symmetry changes for four of the five synthesis methodologies employed. Only the EDTA complexing sol–gel method, where EDTA is used as dissolver and chelating agent, is not satisfactory in all concentration ranges. Rietveld results suggest that the degree of distortion of the rhombohedral symmetry in the crystallized BiFeO 3 powders decreases 12% as a result of progressive substitution of Bi 3+ by Ba 2+ and that there is no shift from rhombohedral to tetragonal symmetry. Magnetization properties of samples with a low-distortion rhombohedral structure show higher magnetic saturation and remanent magnetization than samples with high-distortion rhombohedral structure. - Highlights: • Ba–BiFeO 3 : rhombohedral distortion degree is highly affected by the chemical method. • Rietveld results show no shift in BBFO from rhombohedral to tetragonal symmetry. • The low-distortion rhombohedral structure show higher magnetic saturation. • To stabilize a metal complex is necessary a balance between COOH − and OH − groups

Teamwork in high-risk environments analogous to space

Science.gov (United States)

Kanki, Barbara G.

1990-01-01

Mountaineering expeditions combine a number of factors which make them potentially good analogs to the planetary exploration facet of long-duration space missions. A study of mountain climbing teams was conducted in order to evaluate the usefulness of the environment as a space analog and to specifically identify the factors and issues surrounding teamwork and 'successful' team performance in two mountaineering environments. This paper focuses on social/organizational factors, including team size and structure, leadership styles and authority structure which were found in the sample of 22 climb teams (122 individuals). The second major issue discussed is the construction of a valid performance measure in this high-risk environment.

Face distortion aftereffects evoked by featureless first-order stimulus configurations

Directory of Open Access Journals (Sweden)

Pál eVakli

2012-12-01

Full Text Available After prolonged exposure to a distorted face with expanded or contracted inner features, a subsequently presented normal face appears distorted towards the opposite direction. This phenomenon, termed as face distortion aftereffect (FDAE, is thought to occur as a result of changes in the mechanisms involved in higher order visual processing. However, the extent to which FDAE is mediated by face-specific configural processing is less known. In the present study, we investigated whether similar aftereffects can be induced by stimuli lacking all the typical characteristics of a human face except for its first-order configural properties. We found a significant FDAE after adaptation to a stimulus consisting of three white dots arranged in a triangular fashion and placed in a grey oval. FDAEs occurred also when the adapting and test stimuli differed in size or when the contrast polarity of the adaptor image was changed. However, the inversion of the adapting image as well as the reduction of its contrast abolished the aftereffect entirely. Taken together, our results suggest that higher-level visual areas, which are involved in the processing of facial configurations, mediate the FDAE. Further, while adaptation seems to be largely invariant to contrast polarity, it appears sensitive to orientation and to lower level manipulations that affect the saliency of the inner features.

Modeling Distortion Effects in Class-D Amplifier Filter Inductors

DEFF Research Database (Denmark)

Knott, Arnold; Stegenborg-Andersen, Tore; Thomsen, Ole Cornelius

2010-01-01

Distortion is generally accepted as a quantifier to judge the quality of audio power amplifiers. In switchmode power amplifiers various mechanisms influence this performance measure. After giving an overview of those, this paper focuses on the particular effect of the nonlinearity of the output f...

A new interpretation of distortion artifacts in sweep measurements

DEFF Research Database (Denmark)

Torras Rosell, Antoni; Jacobsen, Finn

2011-01-01

The characterization of acoustical spaces by means of impulse response measurements is often biased by the nonlinear behavior of the loudspeaker used to excite the system under test. In this context the distortion immunity provided by the sweep technique has been investigated. The results show...

SU-G-JeP2-13: Spatial Accuracy Evaluation for Real-Time MR Guided Radiation Therapy Using a Novel Large-Field MRI Distortion Phantom

International Nuclear Information System (INIS)

Antolak, A; Bayouth, J; Bosca, R; Jackson, E

2016-01-01

Purpose: Evaluate a large-field MRI phantom for assessment of geometric distortion in whole-body MRI for real-time MR guided radiation therapy. Methods: A prototype CIRS large-field MRI distortion phantom consisting of a PMMA cylinder (33 cm diameter, 30 cm length) containing a 3D-printed orthogonal grid (3 mm diameter rods, 20 mm apart), was filled with 6 mM NiCl_2 and 30 mM NaCl solution. The phantom was scanned at 1.5T and 3.0T on a GE HDxt and Discovery MR750, respectively, and at 0.35T on a ViewRay system. Scans were obtained with and without 3D distortion correction to demonstrate the impact of such corrections. CT images were used as a reference standard for analysis of geometric distortion, as determined by a fully automated gradient-search method developed in Matlab. Results: 1,116 grid points distributed throughout a cylindrical volume 28 cm in diameter and 16 cm in length were identified and analyzed. With 3D distortion correction, average/maximum displacements for the 1.5, 3.0, and 0.35T systems were 0.84/2.91, 1.00/2.97, and 0.95/2.37 mm, respectively. The percentage of points with less than (1.0, 1.5, 2.0 mm) total displacement were (73%, 92%, 97%), (54%, 85%, 97%), and (55%, 90%, 99%), respectively. A reduced scan volume of 20 × 20 × 10 cm"3 (representative of a head and neck scan volume) consisting of 420 points was also analyzed. In this volume, the percentage of points with less than (1.0, 1.5, 2.0 mm) total displacement were (90%, 99%, 100%), (63%, 95%, 100%), and (75%, 96%, 100%), respectively. Without 3D distortion correction, average/maximum displacements were 1.35/3.67, 1.67/4.46, and 1.51/3.89 mm, respectively. Conclusion: The prototype large-field MRI distortion phantom and developed software provide a thorough assessment of 3D spatial distortions in MRI. The distortions measured were acceptable for RT applications, both for the high field strengths and the system configuration developed by ViewRay.

Joint Impact of Frequency Synchronization Errors and Intermodulation Distortion on the Performance of Multicarrier DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Rugini Luca

2005-01-01

Full Text Available The performance of multicarrier systems is highly impaired by intercarrier interference (ICI due to frequency synchronization errors at the receiver and by intermodulation distortion (IMD introduced by a nonlinear amplifier (NLA at the transmitter. In this paper, we evaluate the bit-error rate (BER of multicarrier direct-sequence code-division multiple-access (MC-DS-CDMA downlink systems subject to these impairments in frequency-selective Rayleigh fading channels, assuming quadrature amplitude modulation (QAM. The analytical findings allow to establish the sensitivity of MC-DS-CDMA systems to carrier frequency offset (CFO and NLA distortions, to identify the maximum CFO that is tolerable at the receiver side in different scenarios, and to find out the optimum value of the NLA output power backoff for a given CFO. Simulation results show that the approximated analysis is quite accurate in several conditions.