Complementary Sensitivity Research Articles

Based on the PS/T Method Control Design of Flexible Systems

The lightly damped resonant poles of flexible system increased norm of coprime factor perturbation, which reduced robust of system after loop shaping design. This paper proposes approaches considering the performance of constraints, to select performance weight function through disturbance attenuation and to adjust the complementary sensitivity weight function through design index. The flexible satellite's attitude control demonstrates that the two approaches are able to rapidly select weight function under ensuring the system's robust and have the ability to depress disturbance.

Occupational solvent exposure during pregnancy and child behaviour at age 2

ObjectivesMany women who work during pregnancy are occupationally exposed to toxicants. The developing central nervous system is highly vulnerable to neurotoxicants such as solvents. Although the neurotoxicity of solvents to...

Enhanced cascade control for a class of integrating processes with time delay

Unlike self-regulating processes, cascade control strategies for control of integrating processes with time delay are limited. A novel series cascade control structure to enhance the closed loop performance is proposed for integrating and time delay processes. The proposed controller structure has only two controllers and a setpoint filter. The inner loop controller is designed based on IMC approach and the primary setpoint filter is based on optimal performance index. The primary load disturbance rejection controller, a PID controller in series with a lead/lag compensator, is designed on the basis of the desired closed-loop complementary sensitivity function. The robustness analysis is carried out using Kharitonov's theorem. Simulation results demonstrate the efficacy of the proposed method by showing satisfactory nominal and robust performances.

Smith Predictor Based Parallel Cascade Control Strategy for Unstable Processes with Application to a Continuous Bioreactor

Abstract In this paper, Smith predictor based parallel cascade control strategy is proposed for enhanced control of continuous bioreactor. The scheme consists of secondary loop and primary loop. The secondary loop controller is designed based on the direct synthesis method. Then, the overall primary loop process model is identified using least square method. A delay compensation strategy is incorporated in the primary loop and the corresponding primary loop delay compensated controller is designed based on the identified primary loop model. For comparison, a simple parallel cascade control and a simple feedback control is also applied to the continuous bioreactor. From the simulation studies, it is observed that delay compensated control strategy provides enhanced closed loop performances compared to that of the simple parallel cascade control and simple feedback control. To analyze the performance in the presence of uncertainties, robustness analysis has been carried out based on sensitivity and complementary sensitivity functions.

Differences between Proximal versus Distal Intraorbital Optic Nerve Diffusion Tensor Magnetic Resonance Imaging Properties in Glaucoma Patients

To analyze in vivo the diffusion tensor magnetic resonance imaging (DT-MRI) properties of the intraorbital optic nerve at two different levels: Proximal to the optic nerve head (ONH) and distal to the ONH at the level of the orbital apex in glaucoma patients. Twenty-four patients with primary open-angle glaucoma were examined. The categorization into early and severe glaucoma was performed by Hodapp's classification. Fifteen healthy individuals served as controls. DT-MRI was performed with a 3T-MR unit. At early stage mean diffusivity (MD) values were higher at the proximal site with respect to the distal site. On the contrary, a decrease in fractional anisotropy (FA) was observed only relative to patient stage, independent of optic nerve site. Moreover, at early disease stage an increase in overall diffusivities, was evident at the proximal site, whereas at the distal site a decrease of the largest diffusivity and an increase in both the intermediate and smallest diffusivities were observed. FA and MD measured at the proximal site, had, respectively, the highest sensitivity and specificity in discriminating between healthy and glaucomatous eyes. Our study represents the first attempt to evaluate in vivo fiber integrity changes along the optic nerve with DT-MRI. Optic nerve degeneration appears to be a process that affects differently the proximal and the distal segments of the optic nerve. The complementary high sensitivity of FA with the high specificity of MD at the proximal site may provide reliable indexes for the identification of glaucomatous patients at early stages.

On the value of including x-component data in 1D modeling of electromagnetic data from helicopterborne time domain systems in horizontally layered environments

Helicopter borne time domain EM systems historically measure only the Z-component of the secondary field, whereas fixed wing systems often measure all field components. For the latter systems the X-component is often used to map discrete conductors, whereas it finds little use in the mapping of layered settings. Measuring the horizontal X-component with an offset loop helicopter system probes the earth with a complementary sensitivity function that is very different from that of the Z-component, and could potentially be used for improving resolution of layered structures in one dimensional modeling. This area is largely unexplored in terms of quantitative results in the literature, since measuring and inverting X-component data from a helicopter system is not straightforward: The signal strength is low, the noise level is high, the signal is very sensitive to the instrument pitch and the sensitivity function also has a complex lateral behavior. The basis of our study is a state of the art inversion scheme, using a local 1D forward model description, in combination with experiences gathered from extending the SkyTEM system to measure the X component. By means of a 1D sensitivity analysis we motivate that in principle resolution of layered structures can be improved by including an X-component signal in a 1D inversion, given the prerequisite that a low-pass filter of suitably low cut-off frequency can be employed. In presenting our practical experiences with modifying the SkyTEM system we discuss why this prerequisite unfortunately can be very difficult to fulfill in practice. Having discussed instrumental limitations we show what can be obtained in practice using actual field data. Here, we demonstrate how the issue of high sensitivity towards instrument pitch can be overcome by including the pitch angle as an inversion parameter and how joint inversion of the Z- and X-components produces virtually the same model result as for the Z-component alone. We conclude that adding helicopter system X-component to a 1D inversion can be used to facilitate higher confidence in the layered result, as the requirements for fitting the data into a 1D model envelope becomes more stringent and the model result thus less prone to misinterpretation.

Time-lapse acoustic, transport, and NMR measurements to characterize microstructural changes of carbonate rocks during injection of CO2-rich water

We investigated how changes induced in the microstructure of carbonate rocks by the injection of [Formula: see text]-rich water affect pore-network properties. In particular, we investigated from multiple perspectives the microstructural changes and types of porosity that alter the observable geophysical properties. We thereby refined our understanding of induced modification of the pore network. Our experimental protocol included a suite of time-lapse acoustic, transport, and nuclear magnetic resonance (NMR) measurements, along with scanning electron microscopy (SEM) and CT-scan images; these gave us complementary sensitivity to changes in different properties of the pore space. Induced porosity variations were smaller than in previous reported results because of chemomechanical compaction resulting from dissolution under pressure. No porosity enhancements larger than 0.8 pu were observed. Results indicated that dissolution occured primarily in the grain-coating cement and the microporosity of the micritic phase. Both caused the formation of cracklike pores around larger grains leading to a more compliant frame, causing both velocity reductions and an increased sensitivity of velocity to pressure. Chalky micritic facies exhibited velocity reductions of [Formula: see text], whereas micritic limestones, less prone to compaction and grain sliding, experienced smaller velocity reductions ([Formula: see text]). Because porosity enhancement was minimal, we hypothesized that the reductions were due to injection-induced reduction of grain-contact stiffness. Dissolution-induced compaction played an integral role also in the permeability response during injection. Compaction in pressure-sensitive chalky facies strongly counteracted the effects of dissolution, leading to negligible permeability and NMR response changes. In contrast, stiff micritic limestones with little dissolution-induced compaction exhibited larger permeability increases ([Formula: see text]). This work demonstrated the advantages of utilizing a suite of concurrent and independent measurements to build a more comprehensive interpretation of microstructure changes induced by injecting fluids that are in chemical disequilibrium with the host formation.

Formula omitted] design with fractional-order [formula omitted] controllers

This article focuses on H∞ performance design for fractional-order systems with time-delay, using fractional-order proportional-derivative (PDμ) controllers. First, the stabilizing parameters region in proportional-derivative plane of PDμ controller, for a fixed derivative-order, is determined in terms of a graphical stability criterion applicable to fractional-order time-delay systems. Then, in the stabilizing region, the pairs of proportional and derivative gains of PDμ controller are calculated for a range of frequencies, which satisfy the H∞-norm constraint of complementary sensitivity function and define the H∞ boundary curve. Finally, by changing the derivative-order of PDμ controller, we observe the relationship between the H∞ curve and the derivative-order. Examples are followed to illustrate the design procedure.

Hanle effect from a dipolar magnetic structure: the case of the solar corona and the case of a star

Context. The context is the magnetic field measurement in external solar or stellar layers by interpreting line polarization measurements and the Hanle effect.Aims. The aim is to model the Hanle effect depolarization by integrating upon a star on the one hand, and by integrating along a line-of-sight through the solar corona on the other hand.Methods. The formalism of the atomic density matrix is recalled. Particular attention was devoted to the four axis rotations necessary to transform the magnetic field reference frame into that of the line-of-sight.Results. In the stellar case, the discrepancy between the results by Lopez Ariste et al. (2011, A&A, 527, A120) and the symmetry considerations by Ignace etal. (2011, A&A, 530, A82) is resolved. In the solar case, the computations of the hydrogen Lyα polarization by Derouich et al. (2010, A&A, 511, A7) are revisited, owing to symmetry considerations. Conclusions. In the stellar case, we confirm that the effect integrated on a star leads to a non-vanishing magnetic depolarization due to the high non-linearity of the Hanle effect. In the solar case, we find that the Hanle sensitivity of hydrogen Lyβ and Lyγ could be better adapted to the measurement of the coronal background magnetic field. They form a pair of lines of different and complementary sensitivity, which makes it possible to determine the full vector. Lyα would be instead adapted to the coronal loop magnetic field measurement, because this field is stronger and suited to the Lyα Hanle sensitivity.

Development and application of a methodology to identify and rank the important factors affecting in-vehicle particulate matter

The present study adopted a two-step approach in the development of a methodology to identify and rank the important factors affecting in-vehicle particulate matter (PM). Firstly, the important factors affecting the monitored vehicular PM were identified using regression trees, considering several factors (meteorology, time-related, indoor sources, on-road, and ventilation) that could impact the vehicular indoor air quality. Secondly, the analysis of variance was used as a complementary sensitivity analysis to the regression tree results to rank the significant factors affecting vehicular PM. In-vehicle PM concentrations and sub-micron particle numbers were mainly influenced by the monthly/seasonal changes. Visibility and ambient PM2.5 additionally influenced the sub-micron particles. Furthermore, this study emphasized the variation of the monitored vehicular PM levels under different combinations of the ranked influential factors.

1P1-H07 予測機能制御の線形補償器表現と外乱オブザーバに基づくテーブル駆動系の制御(生産システム・生産機器メカトロニクス)

This paper describes the linear compensator expression of the Predictive Functional Control (PFC) and the sensitivity/complementary sensitivity functions. On the assumption that the nonlinear compensation terms in the control law is not employed, we derive the pulse transfer function and the state-space description of the PFC controller, which make it possible to analyze the feedback properties. Similarly, those of the sensitivity and the complementary sensitivity functions are also derived. Finally, we apply the demonstrated results to the position control system of a table drive system to confirm that the same results as the standard PFC algorithm are produced.

Synthesis of PID tuning for a new parallel cascade control structure

Most of the published papers on parallel cascade control strategies present improvement of dynamic performance of stable processes. In this paper, a new parallel cascade control scheme is proposed for controlling stable and unstable processes with time delay. The two main features of the proposed scheme are: the primary process output completely tracks the primary setpoint and the servo response decouples the regulatory response in the nominal system. The proposed structure has only two controllers. The inner loop controller is designed based on IMC approach. The outer loop controller is a PID controller in series with lead/lag filter which is designed based on the desired complementary sensitivity function. Significant improvement in the load disturbance rejection performances are obtained when compared to some recent methods in the literature. Simulation results show the superiority and usefulness of the proposed control method over the existing ones.

Robust PID Control of the Quadrotor Helicopter

In this paper a robust PID control strategy via affine parametrization is designed for an multivariable nonlinear unmanned aerial vehicle. The robustness of the controlled system is assured by using the H∞ norm of the weighted complementary sensitivity function. Simulation results carried out using a complete nonlinear model are shown, wherein the performance achieved with this control strategy is shown.

Decoupling of Complementary Sensitivity and Robust Stabilization on Diagonal Dominance

Decoupling of Complementary Sensitivity and Robust Stabilization on Diagonal Dominance

Novel microbiological system for antibiotic detection in ovine milk

This article presents a microbiological system composed of a “BT” bioassay (Beta-lactams and Tetracyclines) and a “QS” bioassay (Quinolones and Sulfonamides). The “BT” bioassay contains spores of Geobacillus stearothermophilus, bromocresol purple and cloramphenicol in a culture medium (incubation time: 2.45h), while the “QS” bioassay uses spores of Bacillus subtilis, trifenyltetrazolium – toluidine blue and trimethoprim in a suitable culture medium (incubation time: 5.5h). The detection capability (CCβ) of 27 antimicrobial agents in ovine milk were determined by logistic regression models. Thus, the “BT” bioassay detects amoxycillin, ampicillin, penicillin “G”, cloxacillin, oxacillin, cephalexin, cefoperazone, ceftiofur, chlortetracycline, oxytetracycline, tetracycline, neomycin, gentamycin and tylosin, while “QS” bioassay detects: ciprofloxacin, enrofloxacin, marbofloxacin, sulfadiazine, sulfadimethoxine, sulfamerazine, sulfamethazine, sulfamethoxazole, sulfathiazole, erythromycin, lincomycin and spiramycin at levels close to their respective Maximum Residue Limits. The simultaneous use of both bioassays detects a large number of antibiotics in milk given each method's adequate complementary sensitivity.

Force Rebalance Controller Synthesis for a Micromachined Vibratory Gyroscope Based on Sensitivity Margin Specifications

This paper presents a design method of force rebalance control for the sense mode of a micromachined vibratory gyroscope with multiobjective. The control strategy is mainly based on constraining sensitivity margin specifications via numerical optimization approach, which embeds the sense mode in a closed-loop system to possess more robust performance. This paper also provides a quantitative methodology of configuring the system parameters to realize the functional electrostatic force feedback control for the microgyroscope in the case of nonideal coupling and external angular disturbance. Theoretical results predicted by the control loop are shown to be in close agreement with the experimental results using a practical microgyroscope, which indicated a satisfactory performance of the proposed control algorithm. The maximums of the sensitivity function and complementary sensitivity function are measured to be 4.5 and 1 dB, resulting in <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GM</i> ≥ 7.84 dB and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PM</i> ≥ 35°. The gyroscope achieves a scale factor of 7.1 mV/deg/s with nonlinearity of 0.2% which is improved by one order of magnitude compared with that of the open loop. The bandwidth is extended to about 98 Hz from 30 Hz in the open loop. The quadrature error and temperature stability of the scale factor are reduced from - 10.33 to -59.22 dB and from 4858 to 646 ppm/ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C with the force rebalance control, respectively.

Global sensitivity analysis: A flexible and efficient framework with an example from stochastic hydrogeology

When investigating, modeling or operating uncertain systems, sensitivity analysis with respect to uncertain model parameters yields valuable information. It helps to quantify the relevance of parameters, to estimate their individual contributions to prediction uncertainty, and to better direct further data acquisition. In this work, we propose a response surface method for global sensitivity analysis (based on the arbitrary polynomial chaos expansion, aPC). The key advantages of our proposed technique are: (1) aPC alleviates the computational burden associated with conventional global sensitivity analysis methods that require many evaluations of a simulation model; (2) the proposed method incorporates arbitrary independent probability densities or weighting functions for the investigated model parameters, thus generalizing several existing methods to reflect the expected relevance of parameters values within their allowable ranges; and (3) our framework allows to incorporate this information while requiring only a finite number of statistical moments for the investigated parameters. We generalize the polynomial-based computation of Sobol indices to arbitrary distributions, and suggest an associated complementary new sensitivity measure based on polynomial representation, which allows both univariate and multivariate global analysis. Compared to Sobol indices, our new weighted measure is absolute rather than relative, and converges faster with increasing order of expansion. We use analytical and hybrid analytical-numerical formulations that further improve computational efficiency. Altogether, we can conduct global sensitivity analysis at computational costs that are almost as low as those of local sensitivity analyses. We illustrate our approach for a 3D groundwater quality and human health risk problem in heterogeneous porous media.

An outlook on future design of hybrid PET/MRI systems

Early diagnosis and therapy increasingly operate at the cellular, molecular, or even at the genetic level. As diagnostic techniques transition from the systems to the molecular level, the role of multimodality molecular imaging becomes increasingly important. Positron emission tomography (PET) and magnetic resonance imaging (MRI) are powerful techniques for in vivo molecular imaging. The inability of PET to provide anatomical information is a major limitation of standalone PET systems. Combining PET and CT proved to be clinically relevant and successfully reduced this limitation by providing the anatomical information required for localization of metabolic abnormalities. However, this technology still lacks the excellent soft-tissue contrast provided by MRI. Standalone MRI systems reveal structure and function but cannot provide insight into the physiology and/or the pathology at the molecular level. The combination of PET and MRI, enabling truly simultaneous acquisition, bridges the gap between molecular and systems diagnosis. MRI and PET offer richly complementary functionality and sensitivity; fusion into a combined system offering simultaneous acquisition will capitalize the strengths of each, providing a hybrid technology that is greatly superior to the sum of its parts. A combined PET/MRI system provides both the anatomical and structural description of MRI simultaneously with the quantitative capabilities of PET. In addition, such a system would allow exploiting the power of MR spectroscopy (MRS) to measure the regional biochemical content and to assess the metabolic status or the presence of neoplasia and other diseases in specific tissue areas. This paper briefly summarizes state-of-the-art developments and latest advances in dedicated hybrid PET/MRI instrumentation. Future prospects and potential clinical applications of this technology will also be discussed.

Modified Smith predictor based cascade control of unstable time delay processes

An improved cascade control structure with a modified Smith predictor is proposed for controlling open-loop unstable time delay processes. The proposed structure has three controllers of which one is meant for servo response and the other two are for regulatory responses. An analytical design method is derived for the two disturbance rejection controllers by proposing the desired closed-loop complementary sensitivity functions. These two closed-loop controllers are considered in the form of proportional–integral-derivative (PID) controller cascaded with a second order lead/lag filter. The direct synthesis method is used to design the setpoint tracking controller. By virtue of the enhanced structure, the proposed control scheme decouples the servo response from the regulatory response in case of nominal systems i.e., the setpoint tracking controller and the disturbance rejection controller can be tuned independently. Internal stability of the proposed cascade structure is analyzed. Kharitonov’s theorem is used for the robustness analysis. The disturbance rejection capability of the proposed scheme is superior as compared to existing methods. Examples are also included to illustrate the simplicity and usefulness of the proposed method.

Invariant sets techniques for Youla–Kučera parameter synthesis

This article addresses an invariant sets approach for Youla–Kučera parameter synthesis using linear matrix inequality (LMI) techniques. Given a linear discrete-time observer-based system affected by bounded disturbances and constraints, the proposed technique furnishes the best Youla parameter in terms of finding an invariant ellipsoidal set satisfying the constraints and having the maximal ellipsoidal projection on the state space. Compared with the results obtained for an observer-based design, the synthesis of a Youla parameter provides a larger ellipsoidal projection and an improved sensitivity function. The price to pay for these achievements in terms of robustness is usually a slow closed-loop performance with degraded complementary sensitivity function. In order to obtain a compromise between robustness and performance two methods are proposed: the first method imposes a new bound on the Lyapunov function decreasing speed and the second refers to the pole placement concept. The aforementioned approaches are finally validated in simulation considering position control of an induction motor.