Статті в журналах: "Principe de compensation des perturbations"

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Jeltsch-Thömmes, Aurich, and Fortunat Joos. "Modeling the evolution of pulse-like perturbations in atmospheric carbon and carbon isotopes: the role of weathering–sedimentation imbalances." Climate of the Past 16, no. 2 (March 4, 2020): 423–51. http://dx.doi.org/10.5194/cp-16-423-2020.

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Abstract. Measurements of carbon isotope variations in climate archives and isotope-enabled climate modeling advance the understanding of the carbon cycle. Perturbations in atmospheric CO2 and in its isotopic ratios (δ13C, Δ14C) are removed by different processes acting on different timescales. We investigate these differences on timescales of up to 100 000 years in pulse-release experiments with the Bern3D-LPX Earth system model of intermediate complexity and by analytical solutions from a box model. On timescales from years to many centuries, the atmospheric perturbations in CO2 and δ13CO2 are reduced by air–sea gas exchange, physical transport from the surface to the deep ocean, and by the land biosphere. Isotopic perturbations are initially removed much faster from the atmosphere than perturbations in CO2 as explained by aquatic carbonate chemistry. On multimillennial timescales, the CO2 perturbation is removed by carbonate compensation and silicate rock weathering. In contrast, the δ13C perturbation is removed by the relentless flux of organic and calcium carbonate particles buried in sediments. The associated removal rate is significantly modified by spatial δ13C gradients within the ocean, influencing the isotopic perturbation of the burial flux. Space-time variations in ocean δ13C perturbations are captured by principal components and empirical orthogonal functions. Analytical impulse response functions for atmospheric CO2 and δ13CO2 are provided. Results suggest that changes in terrestrial carbon storage were not the sole cause for the abrupt, centennial-scale CO2 and δ13CO2 variations recorded in ice during Heinrich stadials HS1 and HS4, though model and data uncertainties prevent a firm conclusion. The δ13C offset between the Penultimate Glacial Maximum and Last Glacial Maximum reconstructed for the ocean and atmosphere is most likely caused by imbalances between weathering, volcanism, and burial fluxes. Our study highlights the importance of isotopic fluxes connected to weathering–sedimentation imbalances, which so far have been often neglected on glacial–interglacial timescales.

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Sun, Tao, Panfeng Wang, Binbin Lian, Sida Liu, and Yapu Zhai. "Geometric accuracy design and error compensation of a one-translational and three-rotational parallel mechanism with articulated traveling plate." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 232, no. 12 (February 1, 2017): 2083–97. http://dx.doi.org/10.1177/0954405416683433.

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The demands for advanced and flexible docking equipment are increasing in the fields of aerospace, shipbuilding and construction machinery. Position and orientation accuracy is one of the most important criteria, which would directly affect the docking quality. Taking a novel one-translational and three-rotational docking equipment, referred to as PaQuad parallel mechanism as example, this article proposed an accuracy improvement strategy by geometric accuracy design and error compensation. Drawing mainly on screw theory, geometric error modeling of PaQuad parallel mechanism was first carried out via four independent routes. Joint perturbations and geometric errors were included in each route error twist. Wrenches due to articulated traveling plate were applied to eliminate joint perturbations. Then, geometric accuracy design was implemented at component and substructure levels. The basic principle was to transfer geometric errors into dimensional or geometric tolerance. High-precision machining/assembling techniques were applied to satisfy the tolerance. Finally, error compensation resorting to kinematic calibration was implemented at mechanism level. It can be summarized as identification modeling, measurement planning, and parameter identification and modification. Maximum deviations of PaQuad parallel mechanism before calibration experiment were 0.01 mm, [Formula: see text], [Formula: see text], and [Formula: see text]. And they become 0.01 mm, [Formula: see text], [Formula: see text], and [Formula: see text] after kinematic calibration. Orientation accuracy of PaQuad parallel mechanism has improved one order of magnitude. It proves the effectiveness of accuracy improvement in terms of geometric accuracy design and error compensation.

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Tang, Peng, Yuehong Dai, and Junfeng Chen. "Nonlinear Robust Control on Yaw Motion of a Variable-Speed Unmanned Aerial Helicopter under Multi-Source Disturbances." Aerospace 9, no. 1 (January 15, 2022): 42. http://dx.doi.org/10.3390/aerospace9010042.

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This paper studies the multi-source disturbances attenuation problem on the yaw motion of unmanned aerial helicopter with a variable-speed rotor. The yaw motion subsystem dominated by an electrically-driven tail rotor is firstly introduced, and its trajectory accuracy requires particularly close attention. To this end, we establish a fourth-order yaw error dynamic equation; subsequently, a nonlinear robust control scheme based on optimal H∞ principle is developed, consisting of laws of virtual functions, parameter estimation and a compensation signal. The novelty of this scheme lies in unifying the techniques to deal with the uncertain parameters, noise perturbations, actuator output fault and external airflow turbulence into a simple framework. Stability analysis guarantees that the yaw closed-loop system has the predefined performance of disturbance suppression in the sense of a finite L2-gain. Comparison results with the extended state observer based backstepping controller verify the effectiveness and superior performance of proposed scheme in an aircraft prototype.

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Grudinin, Viktor S., Valeriy S. Khoroshavin, Alexander V. Zotov, and Sergey V. Grudinin. "Adaptive Iterative Control of Temperature in Greenhouse." Engineering Technologies and Systems 29, no. 3 (September 30, 2019): 383–95. http://dx.doi.org/10.15507/2658-4123.029.201903.383-395.

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Introduction. Creation and development of efficient agricultural complexes providing high yields at minimal time, material, and energy costs is impossible without the use of automatic control systems (ACS), which allow for maintaining the microclimate of the greenhouse with high accuracy. Improvements of the microclimate by ASC are aimed at neutralizing the influence of parametric perturbations of processes inside and outside the greenhouse. Using the example of a temperature control channel in a greenhouse with a heating circuit based on hot piped water supply, an adaptive iterative (search) algorithm for adjusting the components of a proportional-integral-differential (PID) controller in the heating circuit is proposed to ensure the required quality of the control process. Materials and Methods. The management is based on a parametrically uncertain model of temperature in the greenhouse, the structure of which, based on the principle of superposition, is transformed into a form with control and disturbances concentrated on an output coordinate. The use of an adaptive PID controller is based on the real-time analysis of a database containing trends of the controlled process. Using operators of Database Managment System or SQL language, queries evaluate regulation quality in accord with quality assessment. Proportional and differential components of the PID controller are adjusted so that the control system works on the verge of switching to auto-oscillation mode. The resulting static error is compensated by a change in the driving force. Results. Simulation of the real structure of a single-circuit automatic control system with temperature in the greenhouse with built-in regulating, executive and measuring elements, with a delay of a coolant movement was carried out using the software MVTU (SimIn- Tech). The proposed adaptation algorithm, consisting of the additive adjustment of the PID controller coefficients and being conveniently implemented within the SCADA system, was shown to provide the minimum oscillatory temperature maintenance for arbitrary parametric perturbations in the presence of the delay. Discussion and Conclusion. The proposed adaptation algorithm provides for compensation for model uncertainty and disturbances, while achieving the required accuracy of maintaining the temperature in the greenhouse. Results of the study will serve as the basics for development of multi-contour ACS microclimate greenhouses with the examination of the impact and compensation of parametric and structural uncertainty, inertia and nonlinearities of real elements. Our results may be used in many sectors of the national economy to study the general and applied problems of digital adaptive process control.

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Gottlieb, G. L., and G. C. Agarwal. "Compliance of single joints: elastic and plastic characteristics." Journal of Neurophysiology 59, no. 3 (March 1, 1988): 937–51. http://dx.doi.org/10.1152/jn.1988.59.3.937.

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1. Step changes in torque were applied to the elbow or ankle joint of normal human subjects who exerted constant levels of effort. They were instructed to not react to the torque but to allow their limbs to move to a new equilibrium position. In this experimental paradigm, the joint may be characterized by a nonlinear compliant element. The aim of this study was to characterize the elastic properties of the compliant element. 2. Joint elasticity is described by an S-shaped relation between torque and angle (a "compliant characteristic curve"). The stiffness of a joint is greatest for small perturbations and decreases as the size of the perturbation is increased whether the limb is loaded or unloaded from its initial equilibrium. 3. The S shape of the compliant characteristic curve is relatively constant when measured at different initial joint angles from the same initial joint torque. 4. Higher levels of initial muscle torque increase the steepness of the compliant characteristic curve. 5. All changes in initial joint torque and angle preserve the S shape. The inflection point of the characteristic curve is always at the initial equilibrium angle and torque. This shifting of the inflection point of the torque-angle relation implies a fundamental plasticity in joint compliance. The elastic component is not invariant but changes with the joint's initial equilibrium state. 6. Changes in muscle tension and length that result from a perturbation are accompanied by changes in muscle activation. The relationship between perturbation torque and mean equilibrium EMG is similar to that found for voluntary isometric contraction. It is not possible to conclude what proportion of the late EMG response to perturbation is mediated by segmental reflex mechanisms. 7. At the levels of torque used here, changes in joint stiffness are highly correlated with changes in tonic contraction of the muscle opposing the load. This change in stiffness is not the result of antagonist coactivation, which was minimal. 8. The compliant characteristic curves of elbow and ankle are qualitatively similar. The principal difference is due to the greater passive stiffness of the ankle. 9. Our findings are inconsistent with aspects of the theory of invariant characteristics or with models of movement and load compensation that postulate a control scheme based only on the setting of muscle and reflex equilibrium points. The data are also incompatible with models that only control the elastic stiffness of the muscle.

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6

Choe, Keith P. "Physiological and molecular mechanisms of salt and water homeostasis in the nematode Caenorhabditis elegans." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 305, no. 3 (August 1, 2013): R175—R186. http://dx.doi.org/10.1152/ajpregu.00109.2013.

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Intracellular salt and water homeostasis is essential for all cellular life. Extracellular salt and water homeostasis is also important for multicellular organisms. Many fundamental mechanisms of compensation for osmotic perturbations are well defined and conserved. Alternatively, molecular mechanisms of detecting salt and water imbalances and regulating compensatory responses are generally poorly defined for animals. Throughout the last century, researchers studying vertebrates and vertebrate cells made critical contributions to our understanding of osmoregulation, especially mechanisms of salt and water transport and organic osmolyte accumulation. Researchers have more recently started using invertebrate model organisms with defined genomes and well-established methods of genetic manipulation to begin defining the genes and integrated regulatory networks that respond to osmotic stress. The nematode Caenorhabditis elegans is well suited to these studies. Here, I introduce osmoregulatory mechanisms in this model, discuss experimental advantages and limitations, and review important findings. Key discoveries include defining genetic mechanisms of osmolarity sensing in neurons, identifying protein damage as a sensor and principle determinant of hypertonic stress resistance, and identification of a putative sensor for hypertonic stress associated with the extracellular matrix. Many of these processes and pathways are conserved and, therefore, provide new insights into salt and water homeostasis in other animals, including mammals.

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7

Cline, T. W. "Evidence that sisterless-a and sisterless-b are two of several discrete "numerator elements" of the X/A sex determination signal in Drosophila that switch Sxl between two alternative stable expression states." Genetics 119, no. 4 (August 1, 1988): 829–62. http://dx.doi.org/10.1093/genetics/119.4.829.

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Abstract The primary signal for Drosophila sex determination is the number of X chromosomes relative to the number of sets of autosomes. The present report shows that the numerator of this X/A signal appears to be determined by the cumulative dose of a relatively limited number of discrete X-linked genetic elements, two of which are sisterless-a and sisterless-b. This discovery regarding the nature of the sex determination signal grew out of previous studies of both the likely X/A signal target (the feminizing switch gene, Sex-lethal) and two positive regulators of that target gene (sis-a and daughterless). Combinations of genetic perturbations in these three genes had been shown to have synergistic effects. A model proposed in part to account for these interactions generated a large variety of strong predictions for sex-specific synergistic interactions that would be diagnostic for X/A numerator elements and could distinguish them from other components of the sex determination system. All these predictions, as well as other predictions for X/A numerator elements, are shown here to be fulfilled. The most compelling observations involve sexually reciprocal viability effects of duplications of wild-type genes: combinations of sis-a+, sis-b+ and/or Sxl+ duplications are lethal to males but rescue females from the otherwise lethal effects of changes in other components of the sex determination machinery. The many interactions described here illustrate an important principle that may seem counter-intuitive: perturbations of the sex determination signal for Drosophila generally will not appear to affect adult sexual phenotype. This principle follows from the fact that Sxl is involved in dosage compensation as well as sex determination, and from important aspects of the nature and timing of Sxl's regulation both by the X/A signal and by Sxl's own products (positive autoregulation). These factors mask potential effects on adult sexual differentiation by causing the premature death of cells and/or individuals. The fact that the vast array of results presented here conform to this principle is strong evidence in favor of a "binary state" model for Sxl regulation by the X/A signal. This model is favored over an alternative "multiple state" hypothesis that was proposed by others in a different study of the X/A signal. In that same study it was concluded that region 3E8-4F11 of the X chromosome contained especially potent X/A numerator elements.(ABSTRACT TRUNCATED AT 400 WORDS)

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Kanbur, Ravi. "Économie du développement et principe de compensation." Revue internationale des sciences sociales 175, no. 1 (2003): 29. http://dx.doi.org/10.3917/riss.175.0029.

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9

Limarchenko, O., O. Nefedov, and O. Sirenko. "VERIFICATION OF THE CONTROL ALGORITHM FOR RESERVOIRS WITH LIQUID BASED ON THE COMPENSATION OF THE FORCE RESPONSE IN DIFFERENT RANGES OF MANIFESTATION OF NONLINEARITIES." Bulletin Taras Shevchenko National University of Kyiv. Mathematics Mechanics, no. 1 (41) (2020): 51–56. http://dx.doi.org/10.17721/1684-1565.2020.01-41.12.51-56.

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Problem about motion of a reservoir with liquid with a free surface is considered based on the compensation of a force response of the liquid on reservoir walls. Such an approach is selected since usual methods of control of mechanical system motion are mostly intended for linear systems of relatively small dimension. However, models of dynamics of the combined motion of reservoirs with liquid are described with relatively high-dimensional nonlinear systems ordinary differential equations. For obtaining the mathematical model of combined motion of a reservoir with liquid with a free surface we use the Hamilton–Ostrogradskiy variational principle, for which it is possible to determine analytically all internal forces of interaction of system component parts. Namely using this algorithm, we determine the main vector of forces of the liquid pressure on reservoir walls (force response of liquid). The algorithm of the motion control of the reservoir with liquid is based on the inclusion of the compensation of the liquid force response to controlling actions, this reduces the motion of the system reservoir–liquid, where the effect of forces from oscillating liquid on the reservoir motion is eliminated. This algorithm was tested for problems of impulse and vibration disturbance of the translational motion of the system in the horizontal plain. We consider the disturbance of the system motion by a force rectangular impulse applied to the reservoir wall, the duration of the impulse is lesser than a quarter of the period of a liquid free oscillations according to the first normal mode. Amplitudes of the impulse were selected with the purpose of analysis of the behavior of the controlled system in different ranges of manifestation of nonlinearities. We state the problem to verify the accuracy of this algorithm for three ranges of manifestation of nonlinear properties in the system, namely, for the linear range (amplitudes of waves on a free surface h do not exceed 0,1 of the radius of a free surface (  <0,1R); for the weakly nonlinear range (  <0,2R) and for the strongly nonlinear range with maximum amplitudes of waves about  =0,32R. Numerical modeling enables the determination of errors of developed algorithm, which does not exceed 0,5 %, although they insignificantly increase with the increase of amplitudes of oscillations on a free surface of liquid. At the same time perturbations on a free surface of liquid for the controlled motion are always greater than for the uncontrolled motion.

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10

Neufeld, Chris, Pascal van Lieshout, and David Purcell. "Articulatory compensation to second formant perturbations." Journal of the Acoustical Society of America 133, no. 5 (May 2013): 3342. http://dx.doi.org/10.1121/1.4805647.

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Nixon, Terence W., Scott McIntyre, Douglas L. Rothman, and Robin A. de Graaf. "Compensation of gradient-induced magnetic field perturbations." Journal of Magnetic Resonance 192, no. 2 (June 2008): 209–17. http://dx.doi.org/10.1016/j.jmr.2008.02.016.

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12

Jacquet, Laurence, and Dirk Van de Gaer. "Politiques fiscales optimales pour les bas revenus et principe de compensation." Revue économique 66, no. 3 (2015): 579. http://dx.doi.org/10.3917/reco.pr2.0041.

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Tsykunov, A. M. "Robust control algorithms with compensation of bounded perturbations." Automation and Remote Control 68, no. 7 (July 2007): 1213–24. http://dx.doi.org/10.1134/s0005117907070090.

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14

Jackson, Carl P. T., and R. Chris Miall. "Contralateral manual compensation for velocity-dependent force perturbations." Experimental Brain Research 184, no. 2 (November 1, 2007): 261–67. http://dx.doi.org/10.1007/s00221-007-1179-6.

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Dahleh, Mohammed. "On Robust Stability and Performance With Time-Varying Control." Journal of Dynamic Systems, Measurement, and Control 117, no. 4 (December 1, 1995): 635–37. http://dx.doi.org/10.1115/1.2801125.

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The analysis of time-varying control for robust stabilization and performance improvement is considered. This problem has been investigated in recent years from the point of view of assessing the capabilities of time-varying control to stabilize plants with structured norm bounded perturbations. In this paper, it is shown that time-varying compensation provides no improvement over time-invariant compensation for the stability and performance robustness of discrete-time systems with structured, causal, time-varying, and norm-bounded perturbations, where the norm on the perturbations is the l2-induced norm. The results of this paper help in completing the picture for the case of time-varying perturbations.

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Savariaux, Christophe, Pascal Perrier, and Jean‐Pierre Orliaguet. "Compensation abilities to lip perturbations of rounded vowel [u]." Journal of the Acoustical Society of America 93, no. 4 (April 1993): 2424. http://dx.doi.org/10.1121/1.405873.

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Furtat, I. B. "Robust control of electric generator with compensation of perturbations." Journal of Computer and Systems Sciences International 50, no. 5 (October 2011): 785–92. http://dx.doi.org/10.1134/s106423071105008x.

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Tsykunov, A. M. "Robust control with compensation of bounded perturbations and noise." Journal of Computer and Systems Sciences International 53, no. 3 (May 2014): 320–26. http://dx.doi.org/10.1134/s1064230714030150.

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19

Repp, Bruno H. "Compensation for subliminal timing perturbations in perceptual-motor synchronization." Psychological Research Psychologische Forschung 63, no. 2 (June 27, 2000): 106–28. http://dx.doi.org/10.1007/pl00008170.

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20

Ferreira de Loza, A., E. Punta, L. Fridman, G. Bartolini, and S. Delprat. "Nested backward compensation of unmatched perturbations via HOSM observation." Journal of the Franklin Institute 351, no. 5 (May 2014): 2397–410. http://dx.doi.org/10.1016/j.jfranklin.2013.12.011.

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21

Niziolek, Caroline A., and Benjamin Parrell. "Responses to Auditory Feedback Manipulations in Speech May Be Affected by Previous Exposure to Auditory Errors." Journal of Speech, Language, and Hearing Research 64, no. 6S (June 18, 2021): 2169–81. http://dx.doi.org/10.1044/2020_jslhr-20-00263.

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Purpose Speakers use auditory feedback to guide their speech output, although individuals differ in the magnitude of their compensatory response to perceived errors in feedback. Little is known about the factors that contribute to the compensatory response or how fixed or flexible they are within an individual. Here, we test whether manipulating the perceived reliability of auditory feedback modulates speakers' compensation to auditory perturbations, as predicted by optimal models of sensorimotor control. Method Forty participants produced monosyllabic words in two separate sessions, which differed in the auditory feedback given during an initial exposure phase. In the veridical session exposure phase, feedback was normal. In the noisy session exposure phase, small, random formant perturbations were applied, reducing reliability of auditory feedback. In each session, a subsequent test phase introduced larger unpredictable formant perturbations. We assessed whether the magnitude of within-trial compensation for these larger perturbations differed across the two sessions. Results Compensatory responses to downward (though not upward) formant perturbations were larger in the veridical session than the noisy session. However, in post hoc testing, we found the magnitude of this effect is highly dependent on the choice of analysis procedures. Compensation magnitude was not predicted by other production measures, such as formant variability, and was not reliably correlated across sessions. Conclusions Our results, though mixed, provide tentative support that the feedback control system monitors the reliability of sensory feedback. These results must be interpreted cautiously given the potentially limited stability of auditory feedback compensation measures across analysis choices and across sessions. Supplemental Material https://doi.org/10.23641/asha.14167136

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Layton, H. E., E. Bruce Pitman, and Leon C. Moore. "Limit-cycle oscillations and tubuloglomerular feedback regulation of distal sodium delivery." American Journal of Physiology-Renal Physiology 278, no. 2 (February 1, 2000): F287—F301. http://dx.doi.org/10.1152/ajprenal.2000.278.2.f287.

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A mathematical model was used to evaluate the potential effects of limit-cycle oscillations (LCO) on tubuloglomerular feedback (TGF) regulation of fluid and sodium delivery to the distal tubule. In accordance with linear systems theory, simulations of steady-state responses to infinitesimal perturbations in single-nephron glomerular filtration rate (SNGFR) show that TGF regulatory ability (assessed as TGF compensation) increases with TGF gain magnitude γ when γ is less than the critical value γc, the value at which LCO emerge in tubular fluid flow and NaCl concentration at the macula densa. When γ > γc and LCO are present, TGF compensation is reduced for both infinitesimal and finite perturbations in SNGFR, relative to the compensation that could be achieved in the absence of LCO. Maximal TGF compensation occurs when γ ≈ γc. Even in the absence of perturbations, LCO increase time-averaged sodium delivery to the distal tubule, while fluid delivery is little changed. These effects of LCO are consequences of nonlinear elements in the TGF system. Because increased distal sodium delivery may increase the rate of sodium excretion, these simulations suggest that LCO enhance sodium excretion.

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Wen, JianHua, ChangMao Qin, and Xin Zhang. "ADRC Attitude Controller Design for Hypersonic Vehicle based on MIMO-ESO." MATEC Web of Conferences 214 (2018): 03003. http://dx.doi.org/10.1051/matecconf/201821403003.

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For the hypersonic vehicle nonlinear attitude mode in reentry process with a strong coupling, aerodynamic parameter perturbations and non-deterministic, combine extended state observer and nonlinear law state error feedback, design the hypersonic vehicle MIMO-ESO ADRC attitude controller. Put interference such as uncertainty, coupling and parameter perturbations as “the sum of interference” ,use the extended state observer to estimate and dynamic feedback compensation, use nonlinear law state error feedback to inhibit residual of compensation. ADRC controller is charged without a precise model of vehicle , and without precise perturbation boundaries of aerodynamic parameters.Simulation results show that the MIMO-ESO ADRC attitude controller can overcome the impact of large-scale perturbations of interference and aerodynamic parameters, have good dynamic qualities and tracking capabilities, also have strong robustness.

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Cernea, Michael M. "Pour une nouvelle économie de la réinstallation : critique sociologique du principe de compensation." Revue internationale des sciences sociales 175, no. 1 (2003): 39. http://dx.doi.org/10.3917/riss.175.0039.

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Houde, John, Srikantan Nagarajan, and Theda Heinks‐Maldonado. "Dynamic cortical imaging of speech compensation for auditory feedback perturbations." Journal of the Acoustical Society of America 121, no. 5 (May 2007): 3045. http://dx.doi.org/10.1121/1.4781744.

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Bernitsas, M. M., and D. Suryatama. "Structural Redesign by Large Admissible Perturbations With Static Mode Compensation." Journal of Offshore Mechanics and Arctic Engineering 121, no. 1 (February 1, 1999): 39–46. http://dx.doi.org/10.1115/1.2829553.

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The method of LargE Admissible Perturbations (LEAP) solves redesign problems of complex structures without trial and error or repetitive finite element analyses. Code RESTRUCT (Redesign of STRUCTures) produces an optimal redesign of minimum structural change or minimum weight with modal dynamics and/or static displacement specifications. LEAP allows for large structural changes. First, the general perturbation equations are derived relating the original structure S1 (known) to the objective structure S2 (unknown) which is to satisfy the designer’s specifications. Next, the redesign problem is solved using an incremental prediction-correction scheme. In the past, LEAP produced accurate results even for 100–300 percent changes in redesign for modal objectives without any intermediate FEAs. Accuracy in static redesign, however, was limited to about 50 percent changes in static objectives. In this work, a new static general perturbation equation and the corresponding LEAP algorithm are developed to achieve accuracy for 100–300 percent changes in static performance as well. The new formulation includes the static deflection shape as the zeroth mode in the expansion of static properties in terms of dynamic modes. Systematic numerical applications show that high accuracy is achieved by fewer extracted modes.

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Grip, Håvard Fjær, Tor A. Johansen, Lars Imsland, and Glenn-Ole Kaasa. "Parameter estimation and compensation in systems with nonlinearly parameterized perturbations." Automatica 46, no. 1 (January 2010): 19–28. http://dx.doi.org/10.1016/j.automatica.2009.10.013.

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Raharjo, Inez, Hardik Kothare, Srikantan S. Nagarajan, and John F. Houde. "Speech compensation responses and sensorimotor adaptation to formant feedback perturbations." Journal of the Acoustical Society of America 149, no. 2 (February 2021): 1147–61. http://dx.doi.org/10.1121/10.0003440.

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29

Smith, Dante J., Cara Stepp, Frank H. Guenther, and Elaine Kearney. "Contributions of Auditory and Somatosensory Feedback to Vocal Motor Control." Journal of Speech, Language, and Hearing Research 63, no. 7 (July 17, 2020): 2039–53. http://dx.doi.org/10.1044/2020_jslhr-19-00296.

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Purpose To better define the contributions of somatosensory and auditory feedback in vocal motor control, a laryngeal perturbation experiment was conducted with and without masking of auditory feedback. Method Eighteen native speakers of English produced a sustained vowel while their larynx was physically and externally displaced on a subset of trials. For the condition with auditory masking, speech-shaped noise was played via earphones at 90 dB SPL. Responses to the laryngeal perturbation were compared to responses by the same participants to an auditory perturbation experiment that involved a 100-cent downward shift in fundamental frequency ( f o ). Responses were also examined in relation to a measure of auditory acuity. Results Compensatory responses to the laryngeal perturbation were observed with and without auditory masking. The level of compensation was greatest in the laryngeal perturbation condition without auditory masking, followed by the condition with auditory masking; the level of compensation was smallest in the auditory perturbation experiment. No relationship was found between the degree of compensation to auditory versus laryngeal perturbations, and the variation in responses in both perturbation experiments was not related to auditory acuity. Conclusions The findings indicate that somatosensory and auditory feedback control mechanisms work together to compensate for laryngeal perturbations, resulting in the greatest degree of compensation when both sources of feedback are available. In contrast, these two control mechanisms work in competition in response to auditory perturbations, resulting in an overall smaller degree of compensation. Supplemental Material https://doi.org/10.23641/asha.12559628

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Ishikawa, Koji, Akari Ishihara, and Hisao Moriya. "Exploring the Complexity of Protein-Level Dosage Compensation that Fine-Tunes Stoichiometry of Multiprotein Complexes." PLOS Genetics 16, no. 10 (October 28, 2020): e1009091. http://dx.doi.org/10.1371/journal.pgen.1009091.

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Proper control of gene expression levels upon various perturbations is a fundamental aspect of cellular robustness. Protein-level dosage compensation is one mechanism buffering perturbations to stoichiometry of multiprotein complexes through accelerated proteolysis of unassembled subunits. Although N-terminal acetylation- and ubiquitin-mediated proteasomal degradation by the Ac/N-end rule pathway enables selective compensation of excess subunits, it is unclear how widespread this pathway contributes to stoichiometry control. Here we report that dosage compensation depends only partially on the Ac/N-end rule pathway. Our analysis of genetic interactions between 18 subunits and 12 quality control factors in budding yeast demonstrated that multiple E3 ubiquitin ligases and N-acetyltransferases are involved in dosage compensation. We find that N-acetyltransferases-mediated compensation is not simply predictable from N-terminal sequence despite their sequence specificity for N-acetylation. We also find that the compensation of Pop3 and Bet4 is due in large part to a minor N-acetyltransferase NatD. Furthermore, canonical NatD substrates histone H2A/H4 were compensated even in its absence, suggesting N-acetylation-independent stoichiometry control. Our study reveals the complexity and robustness of the stoichiometry control system.

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31

Tighilet, Brahim. "Compensation vestibulaire et vieillissement." médecine/sciences 37, no. 10 (October 2021): 851–62. http://dx.doi.org/10.1051/medsci/2021144.

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Le système vestibulaire possède une remarquable capacité d’autoréparation. La compensation vestibulaire, un modèle de plasticité post-lésionnelle du système nerveux central, se réfère à un ensemble de mécanismes endogènes de neuroplasticité dans les noyaux vestibulaires en réponse à des atteintes du système vestibulaire périphérique et sous-tendant la restauration fonctionnelle. Au cours du vieillissement, cette plasticité « homéostatique », bien que toujours présente, s’amenuise et s’accompagne de perturbations sensorimotrices et cognitives. Indépendamment de l’âge, la compensation vestibulaire peut être améliorée par la thérapie pharmacologique mais également par une rééducation fondée sur le renforcement des autres modalités sensorielles, telles que la vision ou la proprioception, mais aussi celui des composantes cognitive et motrice. Dans cet article, nous décrivons d’abord les mécanismes neurobiologiques de la compensation vestibulaire, puis nous discutons l’impact du vieillissement sur cette plasticité adaptative.

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32

Tighilet, Brahim. "Compensation vestibulaire et vieillissement." médecine/sciences 37, no. 10 (October 2021): 851–62. http://dx.doi.org/10.1051/medsci/2021144.

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Анотація:

Le système vestibulaire possède une remarquable capacité d’autoréparation. La compensation vestibulaire, un modèle de plasticité post-lésionnelle du système nerveux central, se réfère à un ensemble de mécanismes endogènes de neuroplasticité dans les noyaux vestibulaires en réponse à des atteintes du système vestibulaire périphérique et sous-tendant la restauration fonctionnelle. Au cours du vieillissement, cette plasticité « homéostatique », bien que toujours présente, s’amenuise et s’accompagne de perturbations sensorimotrices et cognitives. Indépendamment de l’âge, la compensation vestibulaire peut être améliorée par la thérapie pharmacologique mais également par une rééducation fondée sur le renforcement des autres modalités sensorielles, telles que la vision ou la proprioception, mais aussi celui des composantes cognitive et motrice. Dans cet article, nous décrivons d’abord les mécanismes neurobiologiques de la compensation vestibulaire, puis nous discutons l’impact du vieillissement sur cette plasticité adaptative.

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33

Jin, Guang, and Mingcong Deng. "Operator-based nonlinear free vibration control of a flexible plate with sudden perturbations." Transactions of the Institute of Measurement and Control 42, no. 7 (December 20, 2019): 1375–87. http://dx.doi.org/10.1177/0142331219891352.

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In this paper, a new nonlinear vibration control scheme using piezoelectric actuator is proposed for a flexible plate with a free vibration and sudden perturbations. First, the effect of hysteresis nonlinearity from the piezoelectric actuator is considered by Prandtl-Ishlinskii (P-I) hysteresis model. Simultaneously, a dynamic model of the flexible plate with piezoelectric actuator is considered. Then, based on the dynamic model of the flexible plate, operator-based controllers are designed to guarantee the robust stability of the nonlinear control system. In addition, for ensuring the desired vibration control performance of the flexible plate with a free vibration and sudden perturbations, operator-based compensation method is given by the proposed design scheme. In the designed compensator, the desired compensation performances of tracking and of perturbations are obtained by increasing the number of designed n-times feedback loops. Finally, both of numerical simulation and experimental result are shown to verify the effectiveness of the proposed design scheme.

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34

Bykov, V. N., and A. A. Mitin. "Compensation of thermooptic perturbations in a conductivity cooled waveguide active element." Soviet Journal of Quantum Electronics 16, no. 1 (January 31, 1986): 129–30. http://dx.doi.org/10.1070/qe1986v016n01abeh005240.

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35

Dietz, V., M. Trippel, M. Discher, and G. A. Horstmann. "Compensation of human stance perturbations: Selection of the appropriate electromyographic pattern." Neuroscience Letters 126, no. 1 (May 1991): 71–74. http://dx.doi.org/10.1016/0304-3940(91)90374-3.

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36

Yan, T. H., B. He, X. D. Chen, and X. S. Xu. "The Discrete-Time Sliding Mode Control with Computation Time Delay for Repeatable Run-Out Compensation of Hard Disk Drives." Mathematical Problems in Engineering 2013 (2013): 1–13. http://dx.doi.org/10.1155/2013/505846.

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The presented is a study on the problem of disturbance rejection, specifically the periodic disturbance, by applying discrete-time sliding mode control method. For perturbations such as modeling errors and external disturbances, their compensation is formulated using the designed sliding mode control. To eliminate the effect of these perturbations, the convergence rate between the disturbance and their compensation has been shaped by an additional parameter. Decoupling of the resultant perturbation estimation dynamics from the closed loop dynamics is achieved. Computation time delay is also presented to address the perturbation effects. The approach developed ensures the robustness of the sliding mode dynamics to parameter uncertainties and exogenous disturbances, in addition to the complete rejection of the periodic disturbance component. Satisfactory simulation results as well as experimental ones have been achieved based on a fast servo system of a modern hard disk drive to illustrate the validity of the controller for repeatable run-out (RRO) compensation.

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37

Hu, You Wang, Ji Wen Xiang, and Xiao Yan Sun. "Temperature Compensation Experiment of Love Wave Sensor." Advanced Materials Research 490-495 (March 2012): 673–77. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.673.

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Love wave sensor is one of the most promising SAW sensors for liquid detection, because of acoustic energy can be confined in sensing surface by waveguide layer of Love wave sensor, which resulted in higher sensitivity to surface perturbations. Temperature coefficient of frequency (TCF) has deep effect on effective sensitivity of Love wave sensor. In order to improve the performance of Love wave sensor, the theoretical relationship of TCF on substrates and guiding layers temperature properties is researched. It found that reasonable combinations of substrates and guiding layers was a feasible method to obtain effective temperature compensation, and experimental TCF of sensitive element is reduced to 0.75ppm/°C by this method.

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38

Zhang, Lei, Andreas Straube, and Thomas Eggert. "Under Threshold Position Control, Peripheral Mechanisms Compensate Efficiently for Small Perturbations of Arm Movements." Motor Control 20, no. 1 (January 2016): 87–108. http://dx.doi.org/10.1123/mc.2014-0084.

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Unexpected small perturbations during reaching movements are normally compensated for automatically. Previous studies of such perturbations observed that the movement trajectory converges back to the preplanned end position. The question remains whether peripheral mechanisms formed by intrinsic muscle properties and stretch reflex are efficient for compensating for such perturbations. Even though this is suggested by a threshold position control model highlighting the role of peripheral mechanisms under central control in movement generation, it is neither developed nor extensively tested for this capability. The present study tests how this model can account for the compensation during single-joint fast reaching. Motor responses to transient, unpredictable, small perturbations at different movement phases were measured and compared with the model predictions. The results show good agreement concerning kinematic and dynamic responses. Simulations with altered mechanical parameters of the model suggest that reflexive responses are well tuned to the intrinsic muscle properties. We conclude that under central control, peripheral mechanisms cope efficiently with small transient perturbations.

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39

Oldson, Darren R., Leon C. Moore, and Harold E. Layton. "Effect of sustained flow perturbations on stability and compensation of tubuloglomerular feedback." American Journal of Physiology-Renal Physiology 285, no. 5 (November 2003): F972—F989. http://dx.doi.org/10.1152/ajprenal.00377.2002.

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A mathematical model previously formulated by us predicts that limit-cycle oscillations (LCO) in nephron flow are mediated by tubuloglomerular feedback (TGF) and that the LCO arise from a bifurcation that depends heavily on the feedback gain magnitude, γ, and on its relationship to a theoretically determined critical value of gain, γc. In this study, we used that model to show how sustained perturbations in proximal tubule flow, a common experimental maneuver, can initiate or terminate LCO by changing the values of γ and γc, thus changing the sign of γ - γc. This result may help explain experiments in which intratubular pressure oscillations were initiated by the sustained introduction or removal of fluid from the proximal tubule (Leyssac PP and Baumbach L. Acta Physiol Scand 117: 415–419, 1983). In addition, our model predicts that, for a range of TGF sensitivities, sustained perturbations that initiate or terminate LCO can yield substantial and abrupt changes in both distal NaCl delivery and NaCl delivery compensation, changes that may play an important role in the response to physiological challenge.

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40

Estrada, Antonio, and Leonid M. Frid. "Integral HOSM Semiglobal Controller for Finite-Time Exact Compensation of Unmatched Perturbations." IEEE Transactions on Automatic Control 55, no. 11 (November 2010): 2645–49. http://dx.doi.org/10.1109/tac.2010.2067270.

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41

Kawasaki, Masahiro, and Shuichiro Yokoyama. "Compensation for large tensor modes with iso-curvature perturbations in CMB anisotropies." Journal of Cosmology and Astroparticle Physics 2014, no. 05 (May 29, 2014): 046. http://dx.doi.org/10.1088/1475-7516/2014/05/046.

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42

Ishikawa, Koji, Koji Makanae, Shintaro Iwasaki, Nicholas T. Ingolia, and Hisao Moriya. "Post-Translational Dosage Compensation Buffers Genetic Perturbations to Stoichiometry of Protein Complexes." PLOS Genetics 13, no. 1 (January 25, 2017): e1006554. http://dx.doi.org/10.1371/journal.pgen.1006554.

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43

Untermaier, Jean. "De la compensation comme principe général du droit et de l'implantation de télésièges en site classé." Revue Juridique de l'Environnement 11, no. 4 (1986): 381–412. http://dx.doi.org/10.3406/rjenv.1986.2158.

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44

Cohen, Naftali Y., and Edwin P. Gerber, and Oliver Bühler. "Compensation between Resolved and Unresolved Wave Driving in the Stratosphere: Implications for Downward Control." Journal of the Atmospheric Sciences 70, no. 12 (November 22, 2013): 3780–98. http://dx.doi.org/10.1175/jas-d-12-0346.1.

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Abstract Perturbations to the orographic gravity wave parameterization scheme in an idealized general circulation model reveal a remarkable degree of compensation between the parameterized and the resolved wave driving: when the orographic gravity wave driving is changed, the resolved wave driving tends to change in the opposite direction, so there is little impact on the Brewer–Dobson circulation. Building upon earlier observations of such compensation, an analysis based on quasigeostrophic theory suggests that the compensation between the resolved and parameterized waves is inevitable when the stratosphere is driven toward instability by the parameterized gravity wave driving. This instability, however, is quite likely for perturbations of small meridional length scale in comparison with the Rossby radius of deformation. The insight from quasigeostrophic theory is confirmed in a systematic study with an idealized general circulation model and supported by analyses of comprehensive models. The compensation between resolved and unresolved waves suggests that the commonly used linear separation of the Brewer–Dobson circulation into components (i.e., resolved versus parameterized wave driving) may provide a potentially misleading interpretation of the role of different waves. It may also, in part, explain why comprehensive models tend to agree more on the total strength of the Brewer–Dobson circulation than on the flow associated with individual components. This is of particular relevance to diagnosed changes in the Brewer–Dobson circulation in climate scenario integrations as well.

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45

Ouafi, Abderrazak El, and Noureddine Barka. "Accuracy Enhancement of CNC Multi-Axis Machine Tools through an On-Line Error Identification and Compensation Strategy." Advanced Materials Research 718-720 (July 2013): 1388–93. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.1388.

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In order to improve multi-axis machine accuracy, error compensation techniques have been widely applied. However, the lack of reliable methods for direct, global and comprehensive estimation implies that all compensation techniques are based on off-line sequential error components measurement. These measurements provide static results, and cannot reflect the actual machine conditions. Thus, these results are not representative of the real working conditions because of disturbances from thermal distortions and dynamic perturbations. This paper presents an on-line error identification and compensation approach for CNC multi-axis machine tools. Based on the simultaneous measurement of error components, the proposed identification scheme is built to ensure volumetric error prediction for an adaptive error compensation system. Implemented on a moving bridge type CMM, the approach led to a significant improvement of the three-dimensional measurement accuracy.Compared to the conventional off-line error compensation techniques, the proposed identification and compensation approach can further improve the compensation adaptability and efficiency.

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46

Segtnan, Vegard H., Bjørn-Helge Mevik, Tomas Isaksson, and Tormod Næs. "Low-Cost Approaches to Robust Temperature Compensation in Near-Infrared Calibration and Prediction Situations." Applied Spectroscopy 59, no. 6 (June 2005): 816–25. http://dx.doi.org/10.1366/0003702054280586.

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The traditional way of handling temperature shifts and other perturbations in calibration situations is to incorporate the non-relevant spectral variation in the calibration set by measuring the samples at various conditions. The present paper proposes two low-cost approaches based on simulation and prior knowledge about the perturbations, and these are compared to traditional methods. The first approach is based on augmentation of the calibration matrix through adding simulated noise on the spectra. The second approach is a correction method that removes the non-relevant variation from new spectra. Neither method demands exact knowledge of the perturbation levels. Using the augmentation method it was found that a few, in this case four, selected samples run under different conditions gave approximately the same robustness as running all the calibration samples under different conditions. For the carbohydrate data set, all robustification methods investigated worked well, including the use of pure water spectra for temperature compensation. For the more complex meat data set, only the augmentation method gave comparable results to the full global model.

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47

Franken, Matthias K., Daniel J. Acheson, James M. McQueen, Peter Hagoort, and Frank Eisner. "Consistency influences altered auditory feedback processing." Quarterly Journal of Experimental Psychology 72, no. 10 (March 28, 2019): 2371–79. http://dx.doi.org/10.1177/1747021819838939.

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Previous research on the effect of perturbed auditory feedback in speech production has focused on two types of responses. In the short term, speakers generate compensatory motor commands in response to unexpected perturbations. In the longer term, speakers adapt feedforward motor programmes in response to feedback perturbations, to avoid future errors. The current study investigated the relation between these two types of responses to altered auditory feedback. Specifically, it was hypothesised that consistency in previous feedback perturbations would influence whether speakers adapt their feedforward motor programmes. In an altered auditory feedback paradigm, formant perturbations were applied either across all trials (the consistent condition) or only to some trials, whereas the others remained unperturbed (the inconsistent condition). The results showed that speakers’ responses were affected by feedback consistency, with stronger speech changes in the consistent condition compared with the inconsistent condition. Current models of speech-motor control can explain this consistency effect. However, the data also suggest that compensation and adaptation are distinct processes, which are not in line with all current models.

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48

Goffart, Laurent, Alain Guillaume, and Denis Pélisson. "Compensation for Gaze Perturbation During Inactivation of the Caudal Fastigial Nucleus in the Head-Unrestrained Cat." Journal of Neurophysiology 80, no. 3 (September 1, 1998): 1552–57. http://dx.doi.org/10.1152/jn.1998.80.3.1552.

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Goffart, Laurent, Alain Guillaume, and Denis Pélisson. Compensation for gaze perturbation during inactivation of the caudal fastigial nucleus in the head-unrestrained cat. J. Neurophysiol. 80: 1552–1557, 1998. Muscimol injection in the caudal part of the fastigial nucleus (cFN) leads, in the head-unrestrained cat, to a characteristic dysmetria of saccadic gaze shifts toward visual targets. The goal of the current study was to test whether this pharmacological cFN inactivation impaired the ability to compensate for unexpected perturbations in gaze position during the latency period of the saccadic response. Such perturbations consisted of moving gaze away from the target by a transient electrical microstimulation in the deep layers of the superior colliculus simultaneously with extinction of the visual target. After injection of muscimol in the cFN, targets located in the contralesional hemifield elicited gaze shifts that fell short of the target in both “perturbed” and “unperturbed” trials. The amplitude of the compensatory contraversive gaze shifts in perturbed trials coincided with the predicted amplitude of unperturbed responses starting from the same position. Targets located in the opposite hemifield elicited hypermetric gaze shifts in both trial types, and the error of compensatory responses was not statistically different from that of unperturbed gaze shifts. These results indicate that inactivation of the cFN does not interfere with the ability of the head-unrestrained cat to compensate for ipsiversive or contraversive perturbations in gaze position. Thus the gaze-related feedback signals that are used to compute a reference signal of desired gaze displacement are not impaired by cFN inactivation.

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Bouzid, Allal El Moubarek, Mohamed Zerrougui, Seifeddine Ben Elghali, Karim Beddiar, and Mohamed Benbouzid. "Robust Resonant Controllers for Distributed Energy Resources in Microgrids." Applied Sciences 10, no. 24 (December 14, 2020): 8905. http://dx.doi.org/10.3390/app10248905.

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Motivated by the problem of different types and variations of load in micro-grids, this paper presents robust proportional-resonant controllers with a harmonics compensator based on the internal model principle. These controllers ensure robust tracking of sinusoidal reference signals in distributed energy resource systems subject to load variation with respect to sinusoidal disturbances. The distributed generation resource and the resonant controllers are described using the augmented state system approach, allowing the application of the state feedback technique. In order to minimize the tracking error and ensure robustness against perturbation, a set of linear matrix inequalities (LMIs) are addressed for the synthesizing of controller gains. Finally, results obtained in the simulation for resonant compensators with the distributed energy system are presented, in which the controller is applied to the CC-CA inverter.

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50

Bakshi, Avijit, Paul DiZio, and James R. Lackner. "Rapid adaptation to Coriolis force perturbations of voluntary body sway." Journal of Neurophysiology 121, no. 6 (June 1, 2019): 2028–41. http://dx.doi.org/10.1152/jn.00606.2018.

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Studying adaptation to Coriolis perturbations of arm movements has advanced our understanding of motor control and learning. We have now applied this paradigm to two-dimensional postural sway. We measured how subjects ( n = 8) standing at the center of a fully enclosed rotating room who made voluntary anterior-posterior swaying movements adapted to the Coriolis perturbations generated by their sway. Subjects underwent four voluntary sway trials prerotation, 20 per-rotation at 10 rpm counterclockwise, and 10 postrotation. Each trial lasted 20 s, and subjects were permitted normal vision. Their voluntary sway during rotation generated Coriolis forces that initially induced rightward deviations of their forward sway paths and leftward deviations of their backward sway. Sagittal plane sway was gradually restored over per-rotation trials, and a mirror image aftereffect occurred in postrotation trials. Dual force plate data analysis showed that subjects learned to counter the Coriolis accelerations during rotation by executing a bimodal torque pattern that was asymmetric across legs and contingent on forward vs. backward movement. The experience-dependent acquisition and washout of this compensation indicate that an internal, feedforward model underlies the leg-asymmetric bimodal torque compensation, contingent on forward vs. backward movement. The learned torque asymmetry we observed for forward vs. backward sway is not consistent with parallel two-leg models of postural control. NEW & NOTEWORTHY This paper describes adaptation to Coriolis force perturbations of voluntary sway in a rotating environment. During counterclockwise rotation, sway paths are deviated clockwise, but full restoration of fore-aft sway is regained in minutes. Negative aftereffects are briefly present postrotation. Current parallel leg models of postural control cannot account for these findings, which show that postural control, like arm movement control, can adapt rapidly and completely to the Coriolis forces generated in artificial gravity environments.

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