Feedback Operation Research Articles

Frequency-modulated atomic force microscopy operation by imaging at the frequency shift minimum: the dip-df mode.

In frequency modulated non-contact atomic force microscopy, the change of the cantilever frequency (Δf) is used as the input signal for the topography feedback loop. Around the Δf(z) minimum, however, stable feedback operation is challenging using a standard proportional-integral-derivative (PID) feedback design due to the change of sign in the slope. When operated under liquid conditions, it is furthermore difficult to address the attractive interaction regime due to its often moderate peakedness. Additionally, the Δf signal level changes severely with time in this environment due to drift of the cantilever frequency f0 and, thus, requires constant adjustment. Here, we present an approach overcoming these obstacles by using the derivative of Δf with respect to z as the input signal for the topography feedback loop. Rather than regulating the absolute value to a preset setpoint, the slope of the Δf with respect to z is regulated to zero. This new measurement mode not only makes the minimum of the Δf(z) curve directly accessible, but it also benefits from greatly increased operation stability due to its immunity against f0 drift. We present isosurfaces of the Δf minimum acquired on the calcite CaCO3(101̅4) surface in liquid environment, demonstrating the capability of our method to image in the attractive tip-sample interaction regime.

Study on Virtual Liver Surgery Simulation System with Real-Time Haptic Feedback

To improve the precision and real-time of the virtual liver surgery simulation system with haptic feedback, a novel deformation modelling based on wave equation and spherical harmonic is proposed. Continuous changed liver models were mapped into a common reference system in which corresponding coefficients of spherical harmonic were compared with method of principal components analysis and force feedback were calculated by simplified deformation wave equation. Moreover, system structure design, fast collision detection and real-time feedback operation are also discussed in detail. Experimental platform of virtual liver surgery was established based on vizard 4.0 and Sensable-phantom® desktopTM. Experiment results show that the system can provide a stable force to the human operator and which satisfy the requirement of real-time performance. Establishing a simple and lifelike physics deformation model and a precise and rapid collision detection algorithm favors the performance improvement of the virtual liver surgery simulation system.

OPERATION ACCURACY OF ADAPTIVE FRICTION CLUTCH WITH SEPARATE FORCE CLOSURE

The possibilit y to increase feedback gain and operation accuracy of the adaptive friction clutch is r e vealed at the expense of the friction couple separate force closure of the basic and supplementary friction groups . The load cha racteristic of the clutch is presented i n the form of a curve monotonically i n creasing in the full range of the friction coefficient variation. The obtained results of three options of the coupling fluent param e ters variability have shown that to attain a maximum operation accuracy of the clutch with separate force closure executed according to the second option, it is necessary to take the maximum possible number of friction couples of the basic friction group, and the maximum gain le v el

Leptin levels at birth and infant growth: the EPOCH study.

To examine the association of cord blood leptin with body mass index (BMI) growth velocity from birth to 12 months of age among infants exposed and not exposed to over-nutrition in utero (defined as maternal overweight/obesity or presence of gestational diabetes). 185 infants enrolled in the Exploring Perinatal Outcomes among Children study (76 exposed and 109 not exposed) had leptin and insulin measured in cord blood. Longitudinal weight and length measures in the first 12 months of life (average 4 per participant) obtained from medical records were used to compute BMI growth rates. Mixed models were used to examine associations of cord blood leptin with growth. Compared with unexposed infants, those exposed had significantly higher cord blood insulin (8.64 v. 6.97 uU/ml, P<0.01) and leptin levels (8.89 v. 5.92 ng/ml, P=0.05) as well as increased birth weights (3438.04 v. 3306.89 g, P=0.04). There was an inverse relationship between cord leptin levels and BMI growth from birth to 12 months of age (P=0.005); however, exposure to over-nutrition in utero did not significantly modify this association (P=0.59). We provide support of a possible operational feedback mechanism by which lower cord blood leptin levels are associated with faster infant growth in the first year of life. Our data do not tend to support the hypothesis that this mechanism is altered in infants exposed to over-nutrition in utero; however our sample is too small to provide sufficient evidence. Larger epidemiological studies are needed to elucidate the mechanisms responsible for increased propensity for obesity in exposed offspring.

Control theory for scanning probe microscopy revisited.

We derive a theoretical model for studying SPM feedback in the context of control theory. Previous models presented in the literature that apply standard models for proportional-integral-derivative controllers predict a highly unstable feedback environment. This model uses features specific to the SPM implementation of the proportional-integral controller to give realistic feedback behaviour. As such the stability of SPM feedback for a wide range of feedback gains can be understood. Further consideration of mechanical responses of the SPM system gives insight into the causes of exciting mechanical resonances of the scanner during feedback operation.

A Novel Adaptive Protection Scheme for Microgrid

Based on the analysis of the disadvantages of the several protection schemes for microgrid, the paper proposes a novel current protection scheme for microgrid. The scheme treats the typical microgrid layout as a case study and analyses the principle of operation of adaptive protection in connected mode and islanded mode about three typical faults. In addition, the algorithm and program flow about the adaptive protection, as well as the information feedback mechanism and operation time limit about the bidirectional power flow characteristics have been provided. It improves the technical challenges faced with the protection in different modes to a great extent.

Reversing Quantum Trajectories with Analog Feedback

We demonstrate the active suppression of transmon qubit dephasing induced by dispersive measurement, using parametric amplification and analog feedback. By real-time processing of the homodyne record, the feedback controller reverts the stochastic quantum phase kick imparted by the measurement on the qubit. The feedback operation matches a model of quantum trajectories with a measurement efficiency η˜≈0.5, consistent with the result obtained by postselection. We overcome the bandwidth limitations of the amplification chain by numerically optimizing the signal processing in the feedback loop and provide a theoretical model explaining the optimization result.Received 22 November 2013DOI:https://doi.org/10.1103/PhysRevLett.112.080501© 2014 American Physical Society

Water Quality Supervision of Distribution Networks Based on Machine Learning Algorithms and Operator Feedback

Abstract Water Distribution Networks contain lots of quality sensors placed in the network. Generally, the analysis of this sensor data, e.g. to check for contaminations, is performed manually by the operators and not by data-driven methods. This has several reasons: First, the parameterization of these methods is time consuming; second, many false positive alarms are generated due to special operational actions. This paper addresses both problems: An alarm detection method is presented needing only a few parameters for configuration and the amount of false alarms is reduced, by using known events for training. The approach is tested on a laboratory plant.

Intelligent Operational Feedback Control for Fused Magnesium Furnace

Fused magnesium furnaces (FMF) are widely used in China to extract fused magnesia through a smelting process that has to be well controlled to assure high product output and low power consumption. With manual control, which is still widely used in practice, it is difficult to adjust the setpoints for control loop involved, thereby leading to compromised product output and increased power consumption. In this paper, an operational feedback control method is proposed to control the technical indices within their desired range. This is realized by on-line adjusting the setpoints of control loops for optimal operation of the FMF in response to changes in operating points. The techniques used consist of case based-reasoning (CBR), rule based-reasoning (RBR), neural network (NN), iterative learning control (ILC), in addition to classic PI and PID control. The proposed method and the developed control system have been applied to a real FMF. Industrial applications show the usefulness and effectiveness of the proposed operational feedback control method and its promises in other industrial processes with similar features.

A large-scan-angle piezoelectric MEMS optical scanner actuated by a Nb-doped PZT thin film

Resonant 1D microelectromechanical systems (MEMS) optical scanners actuated by piezoelectric unimorph actuators with a Nb-doped lead zirconate titanate (PNZT) thin film were developed for endoscopic optical coherence tomography (OCT) application. The MEMS scanners were designed as the resonance frequency was less than 125 Hz to obtain enough pixels per frame in OCT images. The device size was within 3.4 mm × 2.5 mm, which is compact enough to be installed in a side-imaging probe with 4 mm inner diameter. The fabrication process started with a silicon-on-insulator wafer, followed by PNZT deposition by the Rf sputtering and Si bulk micromachining process. The fabricated MEMS scanners showed maximum optical scan angles of 146° at 90 Hz, 148° at 124 Hz, 162° at 180 Hz, and 152° at 394 Hz at resonance in atmospheric pressure. Such wide scan angles were obtained by a drive voltage below 1.3 Vpp, ensuring intrinsic safety in in vivo uses. The scanner with the unpoled PNZT film showed three times as large a scan angle as that with a poled PZT films. A swept-source OCT system was constructed using the fabricated MEMS scanner, and cross-sectional images of a fingertip with image widths of 4.6 and 2.3 mm were acquired. In addition, a PNZT-based angle sensor was studied for feedback operation.

Rapid algal culture diagnostics for open ponds using multispectral image analysis

This article presents a multispectral image analysis approach for probing the spectral backscattered irradiance from algal cultures. It was demonstrated how this spectral information can be used to measure algal biomass concentration, detect invasive species, and monitor culture health in real time. To accomplish this, a conventional RGB camera was used as a three band photodetector for imaging cultures of the green alga Chlorella sp. and the cyanobacterium Anabaena variabilis. A novel floating reference platform was placed in the culture, which enhanced the sensitivity of image color intensity to biomass concentration. Correlations were generated between the RGB color vector of culture images and the biomass concentrations for monocultures of each strain. These correlations predicted the biomass concentrations of independently prepared cultures with average errors of 22 and 14%, respectively. Moreover, the difference in spectral signatures between the two strains was exploited to detect the invasion of Chlorella sp. cultures by A. variabilis. Invasion was successfully detected for A. variabilis to Chlorella sp. mass ratios as small as 0.08. Finally, a method was presented for using multispectral imaging to detect thermal stress in A. variabilis. These methods can be extended to field applications to provide delay free process control feedback for efficient operation of large scale algae cultivation systems.

Assessing Satisfaction and Quality in the EMS/HEMS Working Relationship

Background/ObjectiveTreatment provided to critically ill and injured patients during air medical transport bridges initial local emergency medical service (EMS) treatment and the care provided upon arrival to the emergency department. Transition of care from EMS to air medical service includes multiple elements, many of which have been previously undefined. These include operational details surrounding the handoff and attention to issues of continuity in patient care. The purpose of this study is to pilot the development of survey instrumentation to measure key elements of quality in the interaction between EMS and air medical crews. MethodsA focus group of 12 individuals, including rural and urban EMS providers, medical directors, administrators, and air medical transport providers, defined the activities involved in the working relationship between EMS and air medical transport. Ideas were refined into statements and placed into a 16-item Likert scale questionnaire distributed to EMS agencies throughout Ohio. Exploratory factor analysis was performed to identify subscales within the questionnaire. Results380 questionnaires were returned over 2009, 2010, and 2011. Factor analysis of the initial responses from 2009 revealed themes similar to those identified by the focus group: patient care, user-friendly helicopter EMS (HEMS) operations, response time accuracy, operational feedback, and general system issues. The measure had good internal reliability, with alphas for subscales in the 0.85–0.88 range. A modified questionnaire used in 2010 and 2011 actually performed as a single scale. ConclusionUsing qualitative and quantitative approaches, a survey instrument was developed to assess satisfaction with HEMS care from the EMS provider's perspective. Evaluating the EMS perspective on the working relationship with HEMS is a new field of discovery for the air medical transport industry and process improvement activities.

Investigations Into the Design of a Compact Battery-Powered Rep-Rate Capacitor Charger

The U.S. Naval Research Laboratory is developing a battery-powered rep-rate charger for a 60-kJ capacitor bank. The goal is to charge a 4800- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\rm F}$</tex></formula> capacitor to 5 kV in <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${&lt;}{\rm 5}~{\rm s}$</tex></formula> for a 50-shot burst at 10 shots/min. A bank of LiFePO4 batteries is used with a full H-bridge converter, a transformer, and a rectifier to transform the 600 V battery voltage to 5-kV secondary voltage. There are two major aspects to the charger design: battery energy store and the dc–dc converter. A stable battery pack requires active cooling, management, and feedback for proper and safe operation. A design study has been performed to identify an appropriate dc–dc converter that can minimize the weight and volume of the system while maintaining high electrical efficiency. An LLC is being evaluated, as it has the possibility of eliminating a discrete inductor using the magnetizing inductance of the transformer in the resonant circuit. Work has also been performed in the design and evaluation of a battery pack, specifically on characterizing the operational parameters of the pack as applied to the desired load. This paper will present simulation data and results from the experiments.

The Relationship among the Operation Validity, Result Satisfaction, Feedback Acceptance and Teacher Self-development Motivation

The Relationship among the Operation Validity, Result Satisfaction, Feedback Acceptance and Teacher Self-development Motivation

A +9-dBm Output P1db Active Feedback CMOS Wideband LNA for SAW-Less Receivers

A highly linear complementary source follower (CSF) feedback CMOS wideband LNA is implemented as a part of a highly linear receiver front end resilient to 0-dBm out-of-band blockers. Due to the linear feedback operation of the CSF, the proposed LNA greatly improves large-signal linearity performances compared to the conventional SF feedback LNA. The proposed feedback LNA shows an input P1dB close to 0 dBm while achieving an input reflection coefficient less than -10 dB, an average power gain of 10 dB, and a minimum noise figure of 3 dB. The power consumption is 18 mW at a 2-V supply voltage.

Virtual-Production Showing on E-Commerce Based on Cult3D

E-commerce is regarded as the wonderful method to retailer to sell production. Then it is not enough to attract customer to simply provide picture and text of the merchandise. In this paper, both Cult3D and information management technologies are considered to show goods using 3D interactive model online. The file size of web3D model is small and the quality of image is high, which are benefit to internet access. Customer can get more information of the production with operational 3D model and feedback personal requirement.

Evolved design makes ThoraQuik safe and user friendly in the management of pneumothorax and pleural effusion

BackgroundWe have previously described the utility of ThoraQuik, a device designed to be fit for purpose for aspirations of pneumothorax and pleural effusions. We evaluated the safety, efficacy and operator...

Finite-time erasing of information stored in fermionic bits

We address the issue of minimizing the heat generated when erasing the information stored in an array of quantum dots in finite time. We identify the fundamental limitations and trade-offs involved in this process and analyze how a feedback operation can help improve it.

Lacq-Rousse Industrial CCS Reference Project: Description and Operational Feedback after two and Half Years of Operation

Total is committed to reducing the impact of its activities on the environment, especially its greenhouse gas emissions. The group's priorities are to improve the energy efficiency of its industrial facilities, to reduce the flaring of associated gas, to invest in the development of complementary energy sources (biomass, solar, clean coal) and to participate in many operational and R&D programs on CO2 capture, transport and geological storage. It has been involved in CO2 injection and geological storage for over 15 years, in Canada (Weyburn oil field) for EOR and Norway (Sleipner, Snohvit) for aquifer storage. In 2006, the company decided to invest 60 million euros to experiment CO2 capture, transportation and injection in a depleted gas reservoir. The pilot in the Lacq basin, SW France, 800km from Paris, has been on stream since January 2010.The experimental plant is unique in several respects; by its size (unprecedented worldwide), capturing carbon through a 30-MWth oxy-combustion gas boiler, by the choice of a depleted deep onshore gas reservoir (unprecedented in Europe) located onshore 5 kilometers south of the agglomeration of Pau (around 140,000 inhabitants) and by its scope, operating a fully integrated industrial chain (comprising extraction, treatment, combustion of natural gas, High-pressure steam production, CO2 capture, transport and injection) on the SEVESO-classified Lacq industrial complex.The pilot installations were designed by the Total E&P Research and Development team and are operated by Total Exploration Production France. The project reflects Total's commitment to mitigate greenhouse gas emissions.A dedicated plan was devised with the French authorities to monitor the integrity of the injection site and confirm that the CO2 remains trapped in its host reservoir. Its main objectives are to check that no CO2 is leaking upward out of the reservoir though either the injection well or the cap rock, so as to avoid any impact on the groundwater and surface water resources, the biosphere (Fauna and Flora) or human health.This paper details the main technical features of the pilot and the monitoring program spanning subsurface and surface aspects, together with the operational feedback after more than two and half years of operation.Based on the pilot's performance to date, Carbon Capture and Sequestration (CCS) appears to hold promise for use on an industrial scale. This industrial operation will capture and trap up to 90,000 tonnes of Carbon dioxide over a three and half year period. This quantity is equivalent to the exhaust emissions of 30,000 cars over a 2-year period.

Compensation Based Displacement Measurement Using Objective Laser Speckles

Objective laser speckles can be observed as intensity pattern from free space propagation of coherent light that is diffracted from a technically rough surface. Utilizing this pattern allows for very localized non-contacting measurement of surface displacement as well as strain, and carries a high potential for miniaturization. Existing objective speckle techniques suffer from decorrelation effects, dramatically decreasing the performance of such measurement techniques. In this paper we present a compensation based displacement measurement scheme, where we keep the measured speckle pattern displacement close to zero by actively following the measuring objects movement in a feedback operation. This converts the image sensor into a zero-detector, what considerably improves the speckle pattern correlation over a significantly extended measurement range.