Journal articles: 'Shift correction'

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Delhaye, Robert, Volker Rath, Alan G. Jones, Mark R. Muller, and Derek Reay. "Correcting for static shift of magnetotelluric data with airborne electromagnetic measurements: a case study from Rathlin Basin, Northern Ireland." Solid Earth 8, no. 3 (May 22, 2017): 637–60. http://dx.doi.org/10.5194/se-8-637-2017.

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Abstract. Galvanic distortions of magnetotelluric (MT) data, such as the static-shift effect, are a known problem that can lead to incorrect estimation of resistivities and erroneous modelling of geometries with resulting misinterpretation of subsurface electrical resistivity structure. A wide variety of approaches have been proposed to account for these galvanic distortions, some depending on the target area, with varying degrees of success. The natural laboratory for our study is a hydraulically permeable volume of conductive sediment at depth, the internal resistivity structure of which can be used to estimate reservoir viability for geothermal purposes; however, static-shift correction is required in order to ensure robust and precise modelling accuracy.We present here a possible method to employ frequency–domain electromagnetic data in order to correct static-shift effects, illustrated by a case study from Northern Ireland. In our survey area, airborne frequency domain electromagnetic (FDEM) data are regionally available with high spatial density. The spatial distributions of the derived static-shift corrections are analysed and applied to the uncorrected MT data prior to inversion. Two comparative inversion models are derived, one with and one without static-shift corrections, with instructive results. As expected from the one-dimensional analogy of static-shift correction, at shallow model depths, where the structure is controlled by a single local MT site, the correction of static-shift effects leads to vertical scaling of resistivity–thickness products in the model, with the corrected model showing improved correlation to existing borehole wireline resistivity data. In turn, as these vertical scalings are effectively independent of adjacent sites, lateral resistivity distributions are also affected, with up to half a decade of resistivity variation between the models estimated at depths down to 2000 m. Simple estimation of differences in bulk porosity, derived using Archie's Law, between the two models reinforces our conclusion that the suborder of magnitude resistivity contrasts induced by the correction of static shifts correspond to similar contrasts in estimated porosities, and hence, for purposes of reservoir investigation or similar cases requiring accurate absolute resistivity estimates, galvanic distortion correction, especially static-shift correction, is essential.

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Abdullah, Hikmat N., Thamir R. Saeed, and Asaad H. Sahar. "Efficient error correcting scheme for chaos shift keying signals." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 5 (October 1, 2019): 3550. http://dx.doi.org/10.11591/ijece.v9i5.pp3550-3557.

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An effective error-correction scheme based on normalized correlation for a non coherent chaos communication system with no redundancy bits is proposed in this paper. A modified logistic map is used in the proposed scheme for generating two sequences, one for every data bit value, in a manner that the initial value of the next chaotic sequence is set by the second value of the present chaotic sequence of the similar symbol. This arrangement, thus, has the creation of successive chaotic sequences with identical chaotic dynamics for error correction purpose. The detection symbol is performed prior to correction, on the basis of the suboptimal receiver which anchors on the computation of the shortest distance existing between the received sequence and the modified logistic map’s chaotic trajectory. The results of the simulation reveal noticeable Eb/No improvement by the proposed scheme over the prior to the error- correcting scheme with the improvement increasing whenever there is increase in the number of sequence N. Prior to the error-correcting scheme when N=8, a gain of 1.3 dB is accomplished in Eb/No at 10-3 bit error probability. On the basis of normalized correlation, the most efficient point in our proposed error correction scheme is the absence of any redundant bits needed with minimum delay procedure, in contrast to earlier method that was based on suboptimal method detection and correction. Such performance would render the scheme good candidate for applications requiring high rates of data transmission.

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Piotrowski, Tomasz, Krzysztof Kaczmarek, Agata Jodda, Adam Ryczkowski, Tomasz Bajon, George Rodrigues, and Slav Yartsev. "Image guidance procedures in radiotherapy for prostate cancer and the influence of body mass index." Journal of Radiotherapy in Practice 13, no. 4 (April 23, 2014): 410–17. http://dx.doi.org/10.1017/s1460396914000193.

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AbstractPurposeTo investigate possible optimisation of the image guidance procedure for the prostate cancer patients with respect to imaging frequency and patient body mass index (BMI).MethodsThe 6,085 setup correction shifts and BMI for 216 prostate cancer patients treated on tomotherapy units in two centres were analysed. Margins needed to account for inter-fraction target motion with daily only automatic correction and with automatic and manual corrections during one, three or five first fractions as a reference for further treatment without imaging were calculated.ResultsThe planning target volume margin calculated for the daily automatic correction only scheme was significantly lower than the margins calculated for the image guidance limited to a few initial fractions. Manual corrections after automatic fusion were more important for patients with higher BMI. On average, the patients with normal BMI had manual correction shift of 0·7 mm in anterioposterior direction, while overweight and obese patients required, correspondingly, the shifts of 1·3 and 1·4 mm.ConclusionOverweight and obese patients require daily imaging with time saving available by performing automatic kV/MV computed tomography registration only. The patients with normal BMI may be treated with imaging guidance during a few initial treatment fractions.

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Reichenbach, Alexandra, Angela Costello, Peter Zatka-Haas, and Jörn Diedrichsen. "Mechanisms of responsibility assignment during redundant reaching movements." Journal of Neurophysiology 109, no. 8 (April 15, 2013): 2021–28. http://dx.doi.org/10.1152/jn.01052.2012.

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When the two hands act together to achieve a goal, the redundancy of the system makes it necessary to distribute the responsibility for error corrections across the two hands. In an experiment in which participants control a single cursor with the movements of both hands, we show that right-handed individuals correct for movement errors more with their nondominant left hand than with their right hand, even though the dominant right hand corrects the same errors more quickly and efficiently when each hand acts in isolation. By measuring the responses to rapid cursor and target displacements using force channels, we demonstrate that this shift is due to a modulation of the feedback gains of each hand rather than to a shift in the onset of the corrective response. We also show that the shift toward left-hand corrections is more pronounced for errors that lead to adaptation (cursor displacements) than for perturbations that do not (target displacements). This finding provides some support for the idea that the motor system assigns the correction to the most likely source of the error to induce learning and to optimize future performance. Finally, we find that the relative strength of the feedback corrections in the redundant task correlates positively with those found for the nonredundant tasks. Thus the process of responsibility assignment modulates the processes that normally determine the gains of feedback correction rather than completely overwriting them.

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Reinertsen, Ingerid, Frank Lindseth, Christian Askeland, Daniel Høyer Iversen, and Geirmund Unsgård. "Intra-operative correction of brain-shift." Acta Neurochirurgica 156, no. 7 (April 3, 2014): 1301–10. http://dx.doi.org/10.1007/s00701-014-2052-6.

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Admon, Uri. "Specimen shift correction in tilting experiments." Ultramicroscopy 21, no. 3 (January 1987): 297. http://dx.doi.org/10.1016/0304-3991(87)90156-2.

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Jalilov, Ya R., V. Q. Verdiyev, and T. Y. Jalilov. "Application of Cross-Section Corrective («Translation») Forces at Surgical Treatment for Scoliosis." N.N. Priorov Journal of Traumatology and Orthopedics 19, no. 3 (September 15, 2012): 14–19. http://dx.doi.org/10.17816/vto20120314-19.

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Surgical treatment results for 53 patients with III—IV stage of scoliosis are presented. In all patients original endocorrector has been applied. Endocorrector is based on the application of cross-section corrective («translation effect») forces that enable to shift the vertebrae of the main scoliotic arch to the median line of the trunk. Endocorrector was the most effective in curvature arch under 75° and provided 35—45° correction. Mathematic modeling of a situation «endocor- rector—curved spine» was performed as well as the pattern of forces created by endocorrector and participated in the scoliotic deformity correction was studied. Surgical intervention enabled to achieve stable fixation of the spine with its sagittal contours preservation. At long-term follow up (1—6 years) loss of correction did not exceed 8—10°. In scoliosis with arch over 75° step-by- step corrections were performed and loss of correction could make up 15°.

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Sternberg, Ben K., James C. Washburne, and Louise Pellerin. "Correction for the static shift in magnetotellurics using transient electromagnetic soundings." GEOPHYSICS 53, no. 11 (November 1988): 1459–68. http://dx.doi.org/10.1190/1.1442426.

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Shallow inhomogeneities can lead to severe problems in the interpretation of magnetotelluric (MT) data by shifting the MT apparent resistivity sounding curve by a scale factor, which is independent of frequency on the standard log‐apparent‐resistivity versus log‐frequency display. The amount of parallel shift, commonly referred to as the MT static shift, can not be determined directly from conventionally recorded MT data at a single site. One method for measuring the static shift is a controlled‐source measurement of the magnetic field. Unlike the electric field, the magnetic field is relatively unaffected by surface inhomogeneities. The controlled‐source sounding (which may be a relatively shallow sounding made with lightweight equipment) can be combined with a deep MT sounding to obtain a complete, undistorted model of the earth. Inversions of the static shift‐corrected MT data provide a much closer match to well‐log resistivities than do inversions of the uncorrected data. The particular controlled‐source magnetic‐field sounding which we used was a central‐induction Transient ElectroMagnetic (TEM) sounding. Correction for the static shift in the MT data was made by jointly inverting the MT data and the TEM data. A parameter which allowed vertical shifts in the MT apparent resistivity curves was included in the computer inversion to account for static shifts. A simple graphical comparison between the MT apparent resistivities and the TEM apparent resistivities produced essentially the same estimate of the static shift (within 0.1 decade) as the joint computer inversion. Central‐induction TEM measurements were made adjacent to over 100 MT sites in central Oregon. The complete data base of over 100 sites showed an average static shift between 0 and 0.2 decade. However, in the rougher topography and more complex structure of the Cascade Mountain Range, the majority of the sites had static shifts of the order of 0.3 to 0.4 decade. The static shifts in this area are probably due to a combination of topography and surficial inhomogeneities. The TEM apparent resistivity (which is used to estimate the unshifted MT apparent resistivity) does not necessarily agree with either the transverse electric (TE) or the transverse magnetic (TM) MT polarization. TEM apparent resistivity may occur between the two, or may agree with one of the two polarizations, or may lie outside the MT polarizations.

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Stieglitz, Lennart Henning, Christian Ayer, Kaspar Schindler, Markus Florian Oertel, Roland Wiest, and Claudio Pollo. "Improved Localization of Implanted Subdural Electrode Contacts on Magnetic Resonance Imaging With an Elastic Image Fusion Algorithm in an Invasive Electroencephalography Recording." Operative Neurosurgery 10, no. 4 (June 23, 2014): 506–13. http://dx.doi.org/10.1227/neu.0000000000000473.

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Abstract BACKGROUND: Accurate projection of implanted subdural electrode contacts in presurgical evaluation of pharmacoresistant epilepsy cases by invasive electroencephalography is highly relevant. Linear fusion of computed tomography and magnetic resonance images may display the contacts in the wrong position as a result of brain shift effects. OBJECTIVE: A retrospective study in 5 patients with pharmacoresistant epilepsy was performed to evaluate whether an elastic image fusion algorithm can provide a more accurate projection of the electrode contacts on the preimplantation magnetic resonance images compared with linear fusion. METHODS: An automated elastic image fusion algorithm (AEF), a guided elastic image fusion algorithm (GEF), and a standard linear fusion algorithm were used on preoperative magnetic resonance images and postimplantation computed tomography scans. Vertical correction of virtual contact positions, total virtual contact shift, corrections of midline shift, and brain shifts caused by pneumocephalus were measured. RESULTS: Both AEF and GEF worked well with all 5 cases. An average midline shift of 1.7 mm (SD, 1.25 mm) was corrected to 0.4 mm (SD, 0.8 mm) after AEF and to 0.0 mm (SD, 0 mm) after GEF. Median virtual distances between contacts and cortical surface were corrected by a significant amount, from 2.3 mm after linear fusion algorithm to 0.0 mm after AEF and GEF (P < .001). Mean total relative corrections of 3.1 mm (SD, 1.85 mm) after AEF and 3.0 mm (SD, 1.77 mm) after GEF were achieved. The tested version of GEF did not achieve a satisfying virtual correction of pneumocephalus. CONCLUSION: The technique provided a clear improvement in fusion of preimplantation and postimplantation scans, although the accuracy is difficult to evaluate.

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10

Liu, Yong Gang, Da Tong Qin, Zhen Zhen Lei, and Rui Ding. "Intelligent Correction of Shift Schedule for Dual Clutch Transmissions Based on Different Driving Conditions." Applied Mechanics and Materials 121-126 (October 2011): 3982–87. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.3982.

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This paper focuses on intelligent correction of shift schedule for dual clutch transmissions based on different driving conditions. The problem of standard shift schedule has been presented, and the strategy has also been proposed to avoid shift hunting and unexpected shift. The driver’s intention and driving environment have been unified recognized as different driving conditions. A fuzzy logic technology has been used in driver’s attention recognition based on the throttle opening and its derivative. The standard shift schedule has been intelligently corrected at different driving condition separately. An algorithm based on correction coefficient of throttle opening and vehicle speed is proposed for intelligent correction. The corrected shift schedule can be directly used in real time shift control with suitable correction coefficient.

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11

Pachucki, K., D. Leibfried, and T. W. Hänsch. "Nuclear-structure correction to the Lamb shift." Physical Review A 48, no. 1 (July 1, 1993): R1—R4. http://dx.doi.org/10.1103/physreva.48.r1.

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12

Pachucki, Krzysztof. "Radiative recoil correction to the Lamb shift." Physical Review A 52, no. 2 (August 1, 1995): 1079–85. http://dx.doi.org/10.1103/physreva.52.1079.

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13

Lee, Soo‐Y. "Energy shift correction for the reflection approximation." Journal of Chemical Physics 82, no. 10 (May 15, 1985): 4588–94. http://dx.doi.org/10.1063/1.448716.

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Black, James L., and Matthew A. Brzostowski. "Systematics of time‐migration errors." GEOPHYSICS 59, no. 9 (September 1994): 1419–34. http://dx.doi.org/10.1190/1.1443699.

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Even if the correct velocity is used, time migration mispositions events whenever the velocity changes laterally. These errors increase with lateral velocity variation, depth of burial, and dip angle θ. Our analyses of two model types, one with an implicit gradient and one with an explicit gradient, yield simple “rules of thumb” for these errors to first order in the lateral gradient. The x error is [Formula: see text], and the z error is [Formula: see text], where the quantity A = A(x, z) contains the information about depth of burial and magnitude of lateral gradient. These rules can be used to determine when depth migration is needed. Further analysis also shows that the image‐ray correction to time migration is accurate only at small dip. For dipping events, the image‐ray correction must be supplemented by a shift in x of the form [Formula: see text] and a shift in z given by [Formula: see text]. These time‐migration corrections take the same form for both the models we have studied, suggesting a general scheme for correcting time migration, which we call “remedial migration.”

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Dong, C., F. Wu, and H. Chen. "Correction of zero shift in powder diffraction patterns using the reflection-pair method." Journal of Applied Crystallography 32, no. 5 (October 1, 1999): 850–53. http://dx.doi.org/10.1107/s0021889899007396.

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Zero shifts of 2θ usually represent one of the most serious systematic errors in powder patterns obtained by diffractometers, and they cannot be readily diagnosed and corrected. Frequently, large zero shifts hinder indexing of the patterns. Programs exist to refine the lattice constants and calculate the zero shift, but they need the indexing results. We have derived an equation, based on the reflection-pair method, to calculate and correct the zero shift before indexing. The equation has been tested on many experimental data and the effectiveness of the method has been confirmed. The method is very useful inabinitiocrystal structure determination using powder data.

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Ash, Konstantin, and Kevin Mazur. "Identifying and Correcting Signal Shift in DMSP-OLS Data." Remote Sensing 12, no. 14 (July 10, 2020): 2219. http://dx.doi.org/10.3390/rs12142219.

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Defense Meteorological Satellite Program Operational Linescan System (DMSP-OLS) nighttime light data has become a key tool of the environmental and social scientific fields, but suffers from several validity problems. We highlight one such problem—shifts in the digital number position in DMSP-OLS composites in the same satellite. We present techniques for identifying the problem, using moving window raster correlation and visual inspection, and for solving the problem, by assigning control points and manually shifting raster positions. To illustrate the importance of accounting for signal shift, we re-examine a recent analysis of the relationship between public goods provision and patterns of violence in the 2011 Syrian uprising and ensuing civil war. We find the statistical results change considerably when correcting for signal shift. We attribute this change to the systematic undercounting of light intensity in heavily populated areas. We close by identifying the types of research that would most benefit from our correction and suggest future refinements to our technique through automation.

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Clark, A. P., and A. Aftelak. "Doppler-shift correction for a UQPSK satellite modem." International Journal of Satellite Communications 8, no. 5 (September 1990): 337–47. http://dx.doi.org/10.1002/sat.4600080503.

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Metzler, S. D., R. J. Jaszczak, K. L. Greer, and J. E. Bowsher. "Angular-Dependent Axial-Shift Correction for Pinhole SPECT." IEEE Transactions on Nuclear Science 54, no. 1 (February 2007): 124–29. http://dx.doi.org/10.1109/tns.2006.887470.

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Ginzinger, Simon W., Fabian Gerick, Murray Coles, and Volker Heun. "CheckShift: automatic correction of inconsistent chemical shift referencing." Journal of Biomolecular NMR 39, no. 3 (September 26, 2007): 223–27. http://dx.doi.org/10.1007/s10858-007-9191-5.

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Kormos, Donald, Hong-Nin Yeung, and Henry S. Dewhurst. "4661775 Chemical shift imaging with field inhomogeneity correction." Magnetic Resonance Imaging 5, no. 5 (January 1987): VI. http://dx.doi.org/10.1016/0730-725x(87)90153-6.

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Jiao, Weijian, and Stefano Gonella. "Wavenumber-space band clipping in nonlinear periodic structures." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, no. 2251 (July 2021): 20210052. http://dx.doi.org/10.1098/rspa.2021.0052.

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In weakly nonlinear systems, the main effect of cubic nonlinearity on wave propagation is an amplitude-dependent correction of the dispersion relation. This phenomenon can manifest either as a frequency shift or as a wavenumber shift depending on whether the excitation is prescribed as an initial condition or as a boundary condition, respectively. Several models have been proposed to capture the frequency shifts observed when the system is subjected to harmonic initial excitations. However, these models are not compatible with harmonic boundary excitations, which represent the conditions encountered in most practical applications. To overcome this limitation, we present a multiple scales framework to analytically capture the wavenumber shift experienced by dispersion relation of nonlinear monatomic chains under harmonic boundary excitations. We demonstrate that the wavenumber shifts result in an unusual dispersion correction effect, which we term wavenumber-space band clipping. We then extend the framework to locally resonant periodic structures to explore the implications of this phenomenon on bandgap tunability. We show that the tuning capability is available if the cubic nonlinearity is deployed in the internal springs supporting the resonators.

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Leonard, Julia A., Valeriya Gritsenko, Ryan Ouckama, and Paul J. Stapley. "Postural adjustments for online corrections of arm movements in standing humans." Journal of Neurophysiology 105, no. 5 (May 2011): 2375–88. http://dx.doi.org/10.1152/jn.00944.2010.

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The aim of this study was to investigate how humans correct ongoing arm movements while standing. Specifically, we sought to understand whether the postural adjustments in the legs required for online corrections of arm movements are predictive or rely on feedback from the moving limb. To answer this question we measured online corrections in arm and leg muscles during pointing movements while standing. Nine healthy right-handed subjects reached with their dominant arm to a visual target in front of them and aligned with their midline. In some trials, the position of the target would switch from the central target to one of the other targets located 15°, 30°, or 45° to the right of the central (midline) target. For each target correction, we measured the time at which arm kinematics, ground reaction forces, and arm and leg muscle electromyogram significantly changed in response to the target displacement. Results show that postural adjustments in the left leg preceded kinematic corrections in the limb. The corrective postural muscle activity in the left leg consistently preceded the corrective reaching muscle activity in the right arm. Our results demonstrate that corrections of arm movements in response to target displacement during stance are preceded by postural adjustments in the leg contralateral to the direction of target shift. Furthermore, postural adjustments preceded both the hand trajectory correction and the arm-muscle activity responsible for it, which suggests that the central nervous system does not depend on feedback from the moving arm to modify body posture during voluntary movement. Instead, postural adjustments lead the online correction in the arm the same way they lead the initiation of voluntary arm movements. This suggests that forward models for voluntary movements executed during stance incorporate commands for posture that are produced on the basis of the required task demands.

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MAZIASHVILI, MICHAEL, and ZURAB SILAGADZE. "QUANTUM GRAVITATIONAL CORRECTIONS TO THE HYDROGEN ATOM AND HARMONIC OSCILLATOR." International Journal of Modern Physics D 19, no. 02 (February 2010): 137–51. http://dx.doi.org/10.1142/s0218271810016348.

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It is shown that the rate of corrections to the hydrogen atom and harmonic oscillator energy levels due to the profound quantum gravitational effect of space–time dimension running/reduction coincides well with those obtained by means of minimum-length-deformed quantum mechanics. The rate of corrections is pretty much the same within the accuracy with which we can judge the quantum gravitational corrections at all. Such a convergence of results makes the concept of space–time dimension running more appreciable. As a remarkable distinction, the energy shift due to dimension reduction has the opposite sign as compared with the correction obtained by means of minimum-length-modified quantum mechanics. Therefore, the sign of total quantum gravitational correction remains somewhat obscure.

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Nyska, Meir, Hans-Jörg Trnka, Brent G. Parks, and Mark S. Myerson. "Proximal Metatarsal Osteotomies: A Comparative Geometric Analysis Conducted on Sawbone Models." Foot & Ankle International 23, no. 10 (October 2002): 938–45. http://dx.doi.org/10.1177/107110070202301009.

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We evaluated the change in position of the first metatarsal head using a three-dimensional digitizer on sawbone models. Crescentic, closing wedge, oblique shaft (Ludloff 8° and 16°), reverse oblique shaft (Mau 8° and 16°), rotational “Z” (Scarf), and proximal chevron osteotomies were performed and secured using 3-mm screws. The 16° Ludloff provided the most lateral shift (9.5 mm) and angular correction (14.5°) but also produced the most elevation (1.4 mm) and shortening (2.9 mm). The 8° Ludloff provided lateral and angular corrections similar to those of the crescentic and closing wedge osteotomies with less elevation and shortening. Because the displacement osteotomies (Scarf, proximal chevron) provided less angular correction, the same lateral displacement, and less shortening than the basilar angular osteotomies, based upon this model they can be more reliably used for a patient with a mild to moderate deformity, a short first metatarsal, or an intermediate deformity with a large distal metatarsal articular angle. These results can serve as recommendations for selecting the optimal osteotomy with which to correct a deformation.

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CASTELLANOS, E., and T. MATOS. "KLEIN–GORDON FIELDS AND BOSE–EINSTEIN CONDENSATES: THERMAL BATH CONTRIBUTIONS." International Journal of Modern Physics B 27, no. 11 (April 25, 2013): 1350060. http://dx.doi.org/10.1142/s0217979213500604.

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We analyze the consequences caused by a thermal bath upon the properties associated to the symmetry breaking of scalar fields with one-loop correction potential. Concerning the nonrelativistic regime associated with the aforementioned system, we calculate the shift in the condensation temperature caused by the thermal bath, assuming a harmonic oscillator type potential. We prove that the shift in the condensation temperature depends on the associated scale of the system. In addition, we obtain bounds associated to the scale that could lead to relevant corrections on the condensation temperature under typical conditions.

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Pellerin, Louise, and Gerald W. Hohmann. "Transient electromagnetic inversion: A remedy for magnetotelluric static shifts." GEOPHYSICS 55, no. 9 (September 1990): 1242–50. http://dx.doi.org/10.1190/1.1442940.

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Surficial bodies can severely distort magnetotelluric (MT) apparent resistivity data to arbitrarily low frequencies. This distortion, known as the MT static shift, is due to an electric field generated from boundary charges on surficial inhomogeneities, and persists throughout the entire MT recording range. Static shifts are manifested in the data as vertical, parallel shifts of log‐log apparent resistivity sounding curves, the impedance phase being unaffected. Using a three‐dimensional (3-D) numerical modeling algorithm, simulated MT data with finite length electrode arrays are generated. Significant static shifts are produced in this simulation; however, for some geometries they are impossible to identify. Techniques such as spatial averaging and electromagnetic array profiling (EMAP) are effective in removing static shifts, but they are expensive, especially for correcting a previously collected MT data set. Parametric representation and use of a single invariant quantity, such as the impedance tensor determinant, are only useful in limited circumstances and can lead the MT interpreter astray. Transient electromagnetic (TEM) sounding data are relatively inexpensive to collect, do not involve electric field measurements, and are only affected at very early times by surficial bodies. Hence, using TEM data acquired at the same location provides a natural remedy for the MT static shift. We describe a correction scheme to shift distorted MT curves to their correct values based on 1-D inversion of a TEM sounding taken at the same location as the MT site. From this estimated 1-D resistivity structure an MT sounding is computed at frequencies on the order of 1 Hz and higher. The observed MT curves are then shifted to the position of the computed curve, thus eliminating static shifts. This scheme is accurate when the overlap region between the MT and TEM sounding is 1-D, but helpful information can be gleaned even in multidimensional environments. Other advantages of this scheme are that it is straightforward to ascertain if the correction scheme is being accurately applied and it is easy to implement on a personal computer.

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Chen, Chin-Sheng, Cheng-Yi Hsu, Shih-Kang Chen, Chih-Jer Lin, Ching-Hao Hsieh, and Yi-Hung Liu. "Image correction for cone-beam computed tomography simulator using neural network corrector." Advances in Mechanical Engineering 9, no. 2 (February 2017): 168781401769047. http://dx.doi.org/10.1177/1687814017690476.

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In this article, a neural network corrector is proposed to correct the image shift, yielding the degradation of three-dimensional image reconstruction, for each slice captured by cone-beam computed tomography simulator. There are 3 degrees of freedom in tube module of simulator; the central point of tube module should be aligned with the central point of detector module to guarantee the accurate image projection. However, the mechanism manufacturing and assembling tolerance will let the above aim cannot be met. Here, a standard kit is made to measure the image shift by 1° step from −10° to 10°. The measure data will be the input training data of proposed neural network corrector, and the corrected translation position will be the output of neural network corrector. The Levenberg–Marquardt learning algorithm adjusts the connected weights and biases of the neural network using a supervised gradient descent method, such that the defined error function can be minimized. To avoid the problem of overfitting and improve the generalized ability of the neural network, Bayesian regularization is added to the Levenberg–Marquardt learning algorithm. After the training of neural network corrector, the different target position commands are fed into the neural network corrector. Then, the corrected data from neural network corrector are fed to be the new position command to verify the image correction performance. Moreover, a phantom kit is made to check the corrected performance of the neural network corrector. Finally, the experimental results verify that the image shift can be reduced by the neural network corrector.

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Peubey, Carole, and William Bell. "The Influence of Frequency Shifts in Microwave Sounder Channels on NWP Analyses and Forecasts." Journal of Atmospheric and Oceanic Technology 31, no. 4 (April 1, 2014): 788–807. http://dx.doi.org/10.1175/jtech-d-13-00016.1.

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Abstract The sensitivity of numerical weather prediction (NWP) analysis and forecast accuracies with respect to frequency shifts in microwave passbands is quantified through a series of observing system experiments using the ECMWF Integrated Forecast System. First, a parameterization is developed to describe the form and magnitude of the brightness temperature errors arising from frequency shifts in Advanced Microwave Sounding Unit-A (AMSU-A) channels 4–10 and Microwave Humidity Sounder (MHS) channels 3–5. Observing system experiments are then run in which realistic synthetic brightness temperature errors are added to AMSU-A observations for various assumptions about the magnitude of a frequency shift, using the parameterization derived previously. A large negative impact on forecast quality is found when a 20-MHz frequency shift is introduced in experiments using a static bias-correction scheme. Although the degradation in forecast scores is reduced by using a variational bias-correction scheme, it remains around 7%–14% (relative) in RMS 6-h forecast errors for temperature and geopotential. Frequency shifts of 5 MHz or greater give rise to a measurable degradation of the forecast even when the variational correction scheme is used. Only low-frequency shifts (of ~1.5 MHz) are found to have a neutral impact on forecasts. Hence, the value of 1.5 MHz can be regarded as an upper limit below which frequency shifts do not degrade forecasts for the key tropospheric and lower-stratospheric temperature sounding channels in a microwave sounding mission. Calculations show that frequency shift is less problematic for 183-GHz humidity sounding channels due to the symmetric positioning of passbands relative to the 183-GHz absorption line. For these channels a passband center frequency stability of 10 MHz is adequate.

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Novikov-Borodin, Andrey. "Experimental Data Processing Using Shift Methods." EPJ Web of Conferences 226 (2020): 03014. http://dx.doi.org/10.1051/epjconf/202022603014.

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The numerical methods of step-by-step and combined shifts are proposed for correction and reconstruction the experimental data convolved with different blur kernels. Methods use a shift technique for the direct deconvolution of experimental data, they are fast and effective for data reconstruction, especially, in the case of discrete measurements. The comparative analysis of proposed methods is presented, inaccuracies of reconstruction with different blur kernels, different volumes of data and noise levels are estimated. There are presented the examples of using the shift methods in processing the statistical data of TOF neutron spectrometers and in planning the proton therapy treatment. The multi-dimensional data processing using shift methods is considered. The examples of renewal the 2D images blurred by uniform motion and distorted with the Gaussian-like blur kernels are presented.

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Iversen, Daniel Høyer, Wolfgang Wein, Frank Lindseth, Geirmund Unsgård, and Ingerid Reinertsen. "Automatic Intraoperative Correction of Brain Shift for Accurate Neuronavigation." World Neurosurgery 120 (December 2018): e1071-e1078. http://dx.doi.org/10.1016/j.wneu.2018.09.012.

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Pachucki, Krzysztof. "Complete two-loop binding correction to the Lamb shift." Physical Review Letters 72, no. 20 (May 16, 1994): 3154–57. http://dx.doi.org/10.1103/physrevlett.72.3154.

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Zoller, Uri. "Environmental chemistry: The disciplinary/correction-transdisciplinary/prevention paradigm shift." Environmental Science and Pollution Research 7, no. 2 (June 2000): 63–65. http://dx.doi.org/10.1007/bf02987668.

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Luan, Xiaodong, Qingyun Di, Hongzhu Cai, Michael Jorgensen, and Xiaojing Tang. "CSAMT Static Shift Recognition and Correction Using Radon Transformation." IEEE Geoscience and Remote Sensing Letters 15, no. 7 (July 2018): 1001–5. http://dx.doi.org/10.1109/lgrs.2018.2820743.

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Pachucki, K., and S. G. Karshenboim. "Nuclear-spin-dependent recoil correction to the Lamb shift." Journal of Physics B: Atomic, Molecular and Optical Physics 28, no. 7 (April 14, 1995): L221—L224. http://dx.doi.org/10.1088/0953-4075/28/7/004.

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Stavek, Jiri. "On the Trigonometric Description of the Michelson-Morley Experiment." Applied Physics Research 8, no. 4 (July 29, 2016): 134. http://dx.doi.org/10.5539/apr.v8n4p134.

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One formula with two trigonometric corrections describing the round trip of the beams in the Michelson-Morley experiment is presented. The first trigonometric correction describes the round trip path of those beams, while the second trigonometric correction describes the trigonometric geometric mean of the two-way speed of those beams. This formula gives the null fringe shift result for the first order experiments (Fizeau experiment, Hoek experiment), the null fringe shift result for the second order experiment (Michelson-Morley experiment), and predicts a measurable fringe shift result for the fourth order experiment. This trigonometric model can be tested experimentaly by the advanced LIGO (Laser Interferometer Gravitational-Waves Observatory) technology with three arms separated by the angle π/4 and the longitudinal arm directed to the CMB rest frame in the direction to the constellation Crater (known in the Greek mythology as the Cup of the god Apollo). This proposed fourth order experiment can be named as the advanced LIFE (Laser Interferometer Fringe Enigma) experiment. The published predictions before the arrival of experimental data from the advanced LIFE experiment can estimate the power of our models.

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Alkhalifah, Tariq. "Prestack phase‐shift migration of separate offsets." GEOPHYSICS 65, no. 4 (July 2000): 1179–94. http://dx.doi.org/10.1190/1.1444811.

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Prestack phase‐shift migration is implemented by evaluating the offset‐wavenumber ([Formula: see text]) integral using the stationary‐phase method. Thus, the stationary point along [Formula: see text] must be calculated prior to applying the phase shift. This type of implementation allows for migration of separate offsets, as opposed to migration of the whole prestack data when using the original formulas. For zero‐offset data, the stationary point ([Formula: see text]) is known in advance, and, therefore, the phase‐shift migration can be implemented directly. For nonzero‐offset data, we first evaluate the [Formula: see text] that corresponds to the stationary point solution either numerically or through analytical approximations. The insensitivity of the phase to [Formula: see text] around the stationary point solution (its maximum) implies that even an imperfect [Formula: see text] obtained analytically can go a long way to getting an accurate image. In transversely isotropic media, the analytical solutions of the stationary point ([Formula: see text]) include more approximations than those corresponding to isotropic media (i.e., approximations corresponding to weaker anisotropy). Nevertheless, the resultant equations, obtained using Shanks transform and perturbation theory, produce accurate migration signatures for strong anisotropy (η ≈ 0.3) and even large offset‐to‐depth ratios (>2). The analytical solutions are particularly accurate in predicting the nonhyperbolic moveout behavior associated with anisotropic media, a key ingredient to performing an accurate nonhyperbolic moveout inversion for strongly anisotropic media. Although the prestack correction achieved using the phase‐shift method can also be obtained using a cascade of NMO correction, dip‐moveout (DMO) correction, and zero‐offset time migration, the prestack approach can handle sharper velocity models more efficiently. In addition, the resulting operator is sharper than that obtained from the DMO method. Synthetic, including the Marmousi, data applications of the proposed prestack migration demonstrate its usefulness.

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Sysoev, E., R. Kulikov, I. Vykhristyuk, and Yu Chugui. "Correction of Scanning Steps to Improve Accuracy in Interferometric Profilometer." Measurement Science Review 15, no. 1 (February 1, 2015): 9–12. http://dx.doi.org/10.1515/msr-2015-0002.

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Abstract In scanning interferometry of longitudinal shift, an uncertainty of required phase shift performance leads to a measurement error. Such uncertainty can be caused by external factors (vibrations, air turbulence in measuring area etc.) as well as inaccuracy of the scanning system. The method for calculating the phase shift between interferograms, which allows reducing the measurement error, is proposed. The results of numerical and full scale experiments are presented.

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Repp, Bruno H., Justin London, and Peter E. Keller. "Phase Correction in Sensorimotor Synchronization with Nonisochronous Sequences." Music Perception 26, no. 2 (December 1, 2008): 171–75. http://dx.doi.org/10.1525/mp.2008.26.2.171.

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PHASE CORRECTION, WHICH IS NECESSARY for synchronization of movements with a rhythm, has been studied primarily with isochronous sequences.We used a phase perturbation method to examine phase correction in synchronization with nonisochronous sequences (3:2 interval ratios), using musically trained participants. In isochronous control sequences, the phase correction response (PCR) of the tap following a small phase shift was larger when the intervals were long (600 ms) than when they were short (400 ms). In nonisochronous cyclic two-interval patterns, we found a similar dependence of the PCR on the duration of the interval following a phase shift. In three-interval patterns, however, there was no clear dependence on interval duration. The metrical interpretation of the sequences (downbeat location) had no effect on phase correction. In general, phase correction was as effective with nonisochronous as with isochronous sequences.

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Skvortsov, V. S., N. N. Alekseychuk, and A. V. Rybina. "Correction of the electrophoretic shift in virtual 2D SDS-PAGE electrophoresis." Biomeditsinskaya Khimiya 63, no. 3 (2017): 278–83. http://dx.doi.org/10.18097/pbmc20176303278.

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Virtual electrophoresis in proteomics can be used to search localization of proteins and their proteoforms (especially those existing in low concentrations), to identify proteoforms found in experiments etc. Although the problem of predicting the isoelectric point is well studied, the need of electrophoretic shift correction is usually ignored. Researchers simply use the brutto molecular weight of the protein. In this study four data sets taken from the literature sources and the SWISS-2DPAGE database have been used to build correction equations for prediction of the electrophoretic shift (123, 72, 118 and 470 points, respectively). Two groups of models were built. The first model was based on the amino acid composition of proteins, the second one, on analysis of parameters calculated by amino acid sequences (theoretical molecular weight, hydrophobicity, charge distribution, ability to form helix structures). The coefficient of determination ranged from 0.35 to 0.75 in each single set, but cross-prediction between samples did not gave satisfactory results. At the same time, the direction of correction was predicted correctly in 74% of cases. After combining of the samples and dividing pooled data into 2 representative sets, the coefficient of determination during in the process of learning ranged from 0.44 to 0.51, and R2 of predictions were not less than 0.39. The direction of correction was predicted correctly in 80% of cases. This prediction models have been integrated into the program pIPredict v.2, freely available at http://www.ibmc.msk.ru/LPCIT/pIPredict.

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Sakaguchi, Keisuke, Courtney Napoles, Matt Post, and Joel Tetreault. "Reassessing the Goals of Grammatical Error Correction: Fluency Instead of Grammaticality." Transactions of the Association for Computational Linguistics 4 (December 2016): 169–82. http://dx.doi.org/10.1162/tacl_a_00091.

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The field of grammatical error correction (GEC) has grown substantially in recent years, with research directed at both evaluation metrics and improved system performance against those metrics. One unvisited assumption, however, is the reliance of GEC evaluation on error-coded corpora, which contain specific labeled corrections. We examine current practices and show that GEC’s reliance on such corpora unnaturally constrains annotation and automatic evaluation, resulting in (a) sentences that do not sound acceptable to native speakers and (b) system rankings that do not correlate with human judgments. In light of this, we propose an alternate approach that jettisons costly error coding in favor of unannotated, whole-sentence rewrites. We compare the performance of existing metrics over different gold-standard annotations, and show that automatic evaluation with our new annotation scheme has very strong correlation with expert rankings (ρ = 0.82). As a result, we advocate for a fundamental and necessary shift in the goal of GEC, from correcting small, labeled error types, to producing text that has native fluency.

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Sterzing, Florian, Jörn Kalz, Gabriele Sroka-Perez, Kai Schubert, Marc Bischof, Falk Röder, Jürgen Debus, and Klaus Herfarth. "Megavoltage CT in Helical Tomotherapy — Clinical Advantages and Limitations of Special Physical Characteristics." Technology in Cancer Research & Treatment 8, no. 5 (October 2009): 343–52. http://dx.doi.org/10.1177/153303460900800504.

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Helical tomotherapy is a form of image-guided intensity-modulated radiotherapy that introduces the ring gantry concept into radiation oncology. The system is a combination of a therapeutic linear accelerator and a megavoltage CT-scanner. This work describes the clinical experience with megavoltage CT with 456 patients in more than 11000 fractions. It also provides a review of the current literature of the possibilities and limitations of megavoltage CT. Between July 2006 and October 2008 456 patients were treated with helical tomotherapy and a pretreatment megavoltage CT was performed in 98.1% of the 11821 fractions to perform position control and correction. CT image acquisition was done with 3.5 MV x-rays in the helical tomotherapy machine. MVCT was used for dose recalculations to quantify doses distributions in cases of changing geometry, tumor shrinkage or presence of metal implants. Inverse treatment planning for prostate cancer patients with bilateral hip replacements was performed based upon an MVCT. A mean 3D-correction vector of 7.1mm with a considerable variation was detected and immediately corrected. Mean shifts were lateral 0.9mm (sd 5.0mm), mean longitudinal shift 1.0mm (sd 5.1mm) and mean vertical shift 3.2mm (sd 5.2mm). The MVCT enables imaging of anatomical structures in the presence of dental metal or orthopedic implants. Especially in these cases, dose recomputations can increase the precision of dose calculations. Due to a mean 3d correction vector of more than 7mm and a variation of corrections of more than 5mm daily image-guidance is recommended to achieve a precise dose application. The MVCT shows evident advantages in cases with metal implants but has limitations due to a reduced soft tissue contrast. Compared with megavoltage cone-beam-CT the tomotherapy fan beam CT adds less extra dose fore the patient and has a better soft tissue contrast.

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Popovici, Alexander Mihai. "Prestack migration by split‐step DSR." GEOPHYSICS 61, no. 5 (September 1996): 1412–16. http://dx.doi.org/10.1190/1.1444065.

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The double‐square‐root (DSR) prestack migration equation, though defined for depth variable velocity, can be used to image media with strong velocity variations using a phase‐shift plus interpolation (PSPI) or split‐step correction. The split‐step method is based on applying a phase‐shift correction to the extrapolated wavefield—a correction that attempts to compensate for the lateral velocity variations. I show how to extend DSR prestack migration to lateral velocity media and exemplify the method by applying the new algorithm to the Marmousi data set. The split‐step DSR migration is very fast and offers excellent imaging results.

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Chen, Xi, Andrey Smelter, and Hunter N. B. Moseley. "BaMORC: A Software Package for Accurate and Robust 13C Reference Correction of Protein NMR Spectra." Natural Product Communications 14, no. 5 (May 2019): 1934578X1984914. http://dx.doi.org/10.1177/1934578x19849142.

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We describe Bayesian Model Optimized Reference Correction (BaMORC), a software package that performs 13C chemical shifts reference correction for either assigned or unassigned peak lists derived from protein NMR spectra. BaMORC provides an intuitive command line interface that allows non-nuclear magnetic resonance (NMR) experts to detect and correct 13C chemical shift referencing errors of unassigned peak lists at the very beginning of NMR data analysis, further lowering the bar of expertise required for effective protein NMR analysis. Furthermore, BaMORC provides an application programming interface for integration into sophisticated protein NMR data analysis pipelines, both before and after the protein resonance assignment step.

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Agafonov, A. I. "Hydrogen energy-level shifts induced by the atom motion: Crossover from the Lamb shifts to the motion-induced shifts." Modern Physics Letters B 32, no. 23 (August 17, 2018): 1850273. http://dx.doi.org/10.1142/s0217984918502731.

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When the hydrogen atom moves, the proton current generates a magnetic field which interacts with the hydrogen electron. A simple analysis shows that for the hydrogen velocity [Formula: see text] the dominant interaction between the hydrogen momentum and the electron is of order of [Formula: see text], where [Formula: see text] is the fine structure constant, v is the atom velocity, c is the speed of light and m is the electron mass. Using the Bethe–Salpeter equation, the two velocity-dependent operators of this order are derived. As is well known, the degeneracy of the energy levels with the same principal quantum number, n, and the same quantum number of the total angular momentum, j, but the different orbital angular momenta [Formula: see text] is removed by the radiative corrections (the Lamb shift) that are proportional to [Formula: see text]. It is shown that the velocity-dependent perturbation interactions remove this degeneracy as well. There is, however, an important difference between the Lamb shifts and the energy-level shifts induced by the atom motion. The Lamb shift is the diagonal correction to the energy separately for each of the degenerate states. The velocity-dependent perturbation interactions result in the off-diagonal energy corrections between the mutually degenerate states. The joint effect of these two perturbations, which are essentially different in their origin, is analyzed. Given their order of magnitude, the crossover from the Lamb shifts to the motion-induced shifts should occur at the atom velocity [Formula: see text], where [Formula: see text] is a numerical factor dependent on n and j. An experiment using the orbital motion of the Earth is proposed to test the developed theory.

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Duggal, Ritu, R. Arvinth, ShailendraSingh Rana, and OmPrakash Kharbanda. "Simultaneous correction of functional posterior cross bite and midline shift." Contemporary Clinical Dentistry 7, no. 3 (2016): 413. http://dx.doi.org/10.4103/0976-237x.188583.

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Lee, Tae-Hyoung, Oh-Seol Kwon, Tae-Yong Park, Myong-Young Lee, and Yeong-Ho Ha. "Hue-Shift Modeling and Correction Method for High Luminance Display." Journal of Imaging Science and Technology 52, no. 2 (2008): 020602. http://dx.doi.org/10.2352/j.imagingsci.technol.(2008)52:2(020602).

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Reinertsen, I., M. Descoteaux, K. Siddiqi, and D. L. Collins. "Validation of vessel-based registration for correction of brain shift." Medical Image Analysis 11, no. 4 (August 2007): 374–88. http://dx.doi.org/10.1016/j.media.2007.04.002.

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Shah, V., V. Gerginov, P. D. D. Schwindt, S. Knappe, L. Hollberg, and J. Kitching. "Continuous light-shift correction in modulated coherent population trapping clocks." Applied Physics Letters 89, no. 15 (October 9, 2006): 151124. http://dx.doi.org/10.1063/1.2360921.

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Tian, Yong-Hui, and Miklos Kertesz. "Correction to “Charge Shift Bonding Concept in Radical π-Dimers”." Journal of Physical Chemistry A 116, no. 29 (July 16, 2012): 7773. http://dx.doi.org/10.1021/jp306345k.

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Halder, Kalyan Kumar, Manoranjan Paul, Murat Tahtali, Sreenatha G. Anavatti, and Manzur Murshed. "Correction of geometrically distorted underwater images using shift map analysis." Journal of the Optical Society of America A 34, no. 4 (March 31, 2017): 666. http://dx.doi.org/10.1364/josaa.34.000666.

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Journal articles on the topic 'Shift correction'

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