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1

Implementation and validation of atmospheric compensation algorithms for Multispectral Thermal Imager (MTI) pipeline processing  

NASA Astrophysics Data System (ADS)

The Multispectral Thermal Imager (MTI) is a satellite system developed by the DoE. It has 10 spectral bands in the reflectance domain and 5 in the thermal IR. It is pointable and, at nadir, provides 5m IFOV in four visible and short near IR bands and 20m IFOV at longer wavelengths. Several of the bands in the reflectance domain were designed to enable quantitative compensation for aerosol effects and water vapor (daytime). These include 3 bands in and adjacent to the 940nm water vapor feature, a band at 1380nm for cirrus cloud detection and a SWIR band with small atmospheric effects. The concepts and development of these techniques have been described in detail at previous SPIE conferences and in journals. This paper describes the adaptation of these algorithms to the MTI automated processing pipeline (standardized level 2 products) for retrieval of aerosol optical depth (and subsequent compensation of reflectance bands for calibration to reflectance) and the atmospheric water vapor content (thermal IR compensation). Input data sources and flow are described. Validation results are presented. Pre-launch validation was performed using images from the NASA AVIRIS hyperspectral imaging sensor flown in the stratosphere on NASA ER-2 aircraft compared to ground based sun photometer and radiosonde measurements from different sources. These data sets span a range of environmental conditions.

Balick, Lee K.; Hirsch, Karen L.; McLachlan, Peter M.; Borel, Christoph C.; Clodius, William B.; Villeneuve, Pierre V.

2000-11-01

2

Measurement and adaptive compensation of atmospheric phase distortions  

Microsoft Academic Search

A theoretical study of an adaptive algorithm for measuring and compensating for the atmospheric phase distortions of an optical signal is presented. Computer simulation demonstrates a good quality of image reconstruction.

N. D. Ustinov; Iu. A. Zimin; V. V. Protopopov; A. I. Tolmachev

1985-01-01

3

BRIEF COMMUNICATIONS: Determination and adaptive compensation of atmospheric phase distortions  

Microsoft Academic Search

A theoretical study is reported of the adaptive algorithm for the determination and compensation of atmospheric phase distortions of an optical signal. Use is made of a new finesse function. A machine modeling predicts a high quality of image reconstruction.

N. D. Ustinov; Yu A. Zimin; V. V. Protopopov; Alexei I. Tolmachev

1985-01-01

4

Autonomous atmospheric compensation (AAC) of high resolution hyperspectral thermal infrared remote-sensing imagery  

Microsoft Academic Search

Atmospheric emission and absorption significantly modify the thermal infrared (TIR) radiation spectra from Earth's land surface. A new algorithm, autonomous atmospheric compensation (AAC), was developed to estimate and compensate for the atmospheric effects. The algorithm estimates from hyperspectral TIR measurements two atmospheric index parameters, the transmittance ratio, and the path radiance difference between strong and weak absorption channels near the

Degui Gu; Alan R. Gillespie; Anne B. Kahle; Frank D. Palluconi

2000-01-01

5

Atmospheric compensation in the presence of clouds: an adaptive empirical line method (AELM) approach  

Microsoft Academic Search

Many algorithms exist to invert airborne imagery from units of either radiance or sensor specific digital counts to units of reflectance. These compensation algorithms remove unwanted atmospheric variability allowing objects on the ground to be analyzed. Low error levels in homogenous atmospheric conditions have been demonstrated. In many cases however, clouds are present in the atmosphere which introduce error into

Brent Bartlett; John R. Schott

2009-01-01

6

Motion compensation algorithm for widebeam stripmap SAR  

Microsoft Academic Search

In synthetic aperture radar (SAR) imaging, generation of fine resolution imagery requires measurement and compensation for the relative translational and rotational motions between the antenna phase center (APC) and the scene being imaged. A difficulty arises when motion compensating stripmap mode signal history data from a SAR requiring a wide angle azimuth beamwidth. In general, the required compensation varies with

Walter G. Carrara; Sreenidhi Tummala; Ron Goodman

1995-01-01

7

Template based illumination compensation algorithm for multiview video coding  

NASA Astrophysics Data System (ADS)

Recently multiview video coding (MVC) standard has been finalized as an extension of H.264/AVC by Joint Video Team (JVT). In the project Joint Multiview Video Model (JMVM) for the standardization, illumination compensation (IC) is adopted as a useful tool. In this paper, a novel illumination compensation algorithm based on template is proposed. The basic idea of the algorithm is that the illumination of the current block has a strong correlation with its adjacent template. Based on this idea, firstly a template based illumination compensation method is presented, and then a template models selection strategy is devised to improve the illumination compensation performance. The experimental results show that the proposed algorithm can improve the coding efficiency significantly.

Li, Xiaoming; Jiang, Lianlian; Ma, Siwei; Zhao, Debin; Gao, Wen

2010-07-01

8

Using feedback compensation technology to mitigate atmospheric scintillation effect in atmospheric propagation  

NASA Astrophysics Data System (ADS)

As the effects of various weather conditions on laser beams propagating in the atmosphere are hard to mitigate, in order to obtain high quality of the laser propagation, a new method is put forward in this paper. The theory uses feedback compensation technology to mitigate atmospheric scintillation effect, namely collecting the atmospheric turbulence factor in real time, and feedback it to the transmitter of laser real-timely. An experiment and simulation tests to verify the effect of feedback compensation have been taken to analyze the feedback effects and feasibility. The obtained results show the method can mitigate atmospheric scintillation in the atmospheric transmission.

Zhao, Yan; Shen, Shikui; Li, Kun; Ai, Yong

2005-08-01

9

Atmospheric Compensation over Case II Waters: Simultaneous Aerosol and Water Constituent Retrieval  

NASA Astrophysics Data System (ADS)

In many algorithms designed to retrieve water constituent concentrations, an assumption of negligible water-leaving radiance is made in the near infrared (NIR) wavelengths (750-950 [nm]). This allows fairly accurate atmospheric correction to be applied to the oceanic imagery. Given this assumption, it is possible to derive model estimates of aerosol type and density and compensate for its effects in other regions of the spectrum. Unfortunately this assumption is only valid in areas of very low total suspended sediment (TSS) concentrations, such as open ocean waters. Increased TSS load causes significant back-scattering within the water, increasing the water leaving signal in the NIR region, which confounds the compensation algorithms and incorrectly attributes all the effects entirely to aerosols. A possible solution to this problem is to model suspended sediment inherent optical properties (IOPs) in the NIR using the Ocean Optical Phytoplankton Simulator (OOPS) and couple this data using atmospheric and hydrologic radiative transfer models (MODTRAN and HYDROLIGHT, respectively). These models can be combined for a given sensor geometry to predict sensor reaching radiance and match the resulting spectra with actual image spectra. This is done including the NIR which should allow us to better characterize the sediment load. Look-up tables (LUTs) of radiances from modeled atmospheres and reflectances from modeled water allow us to make this an iterative process which can be optimized to give us the best match for the pixel in question. The products of this algorithm are the water constituent concentrations and the atmospheric parameters. This process has been implemented for AVIRIS hyperspectral imagery captured over the Rochester, NY embayment with reasonable success in atmospheric and constituent retrieval.

Taylor, Donald Zoeger

10

Bjerknes Compensation at High Northern Latitudes: The Ocean Forcing the Atmosphere  

E-print Network

, this interaction is confined to the region where the northeast Atlantic and Arctic Oceans connect. The atmosphericBjerknes Compensation at High Northern Latitudes: The Ocean Forcing the Atmosphere E. VAN DER for Bjerknes compensation of heat transport variations through the atmosphere and ocean on decadal time scales

Drijfhout, Sybren

11

In-Scene Atmospheric Characterization and Compensation in Hyperspectral Thermal Infrared Images  

NASA Technical Reports Server (NTRS)

Compensation of thermal infrared radiometric measurements for atmospheric absorption and emission is one of the main factors limiting the accurate estimation of land surface temperatures and emissivities today.

Gillespie, A.; Alley, R.; Kahle, A.; Cothern, S.

1998-01-01

12

A Resistance Compensation Control Algorithm for a Cable-Driven Hand Exoskeleton for Motor Function  

E-print Network

A Resistance Compensation Control Algorithm for a Cable-Driven Hand Exoskeleton for Motor Function@buaa.edu.cn, ryzheng860909@126.com Abstract. The resistance compensation, especially the friction compensation in the Bowden cable transmission is a difficult issue to be handled. Aimed to the resistance reduction

13

Control algorithms for aerobraking in the Martian atmosphere  

NASA Astrophysics Data System (ADS)

The Analytic Predictor Corrector (APC) and Energy Controller (EC) atmospheric guidance concepts have been adapted to control an interplanetary vehicle aerobraking in the Martian atmosphere. Changes are made to the APC to improve its robustness to density variations. These modifications include adaptation of a new exit phase algorithm, an adaptive transition velocity to initiate the exit phase, refinement of the reference dynamic pressure calculation and two improved density estimation techniques. The modified controller with the hybrid density estimation technique is called the Mars Hybrid Predictor Corrector (MHPC), while the modified controller with a polynomial density estimator is called the Mars Predictor Corrector (MPC). A Lyapunov Steepest Descent Controller (LSDC) is adapted to control the vehicle. The LSDC lacked robustness, so a Lyapunov tracking exit phase algorithm is developed to guide the vehicle along a reference trajectory. The equilibrium glide entry phase is used for the first part of the trajectory. This algorithm, when using the hybrid density estimation technique to define the reference path, is called the Lyapunov Hybrid Tracking Controller (LHTC). With the polynomial density estimator used to define the reference trajectory, the algorithm is called the Lyapunov Tracking Controller (LTC). These four new controllers are tested using a six degree of freedom computer simulation to evaluate their robustness. MARS-GRAM is used to develop realistic atmospheres for the study. The atmospheres are then perturbed using square wave density pulses. The MHPC, MPC, LHTC and LRC show dramatic improvements in robustness over the APC and EC. The MHPC, MPC, LHTC and LTC all complete the initial phase of testing (using square wave density pulses) with no failures. The second phase tests the MHPC, MPC, LHTC and LTC against atmospheres where the inbound and outbound density functions are different. Square wave density pulses are again used, but only for the outbound leg of the trajectory. All four controllers are able to compensate for the outbound leg density pulses with no hard failures, but the algorithms are sensitive to large amplitude density pulses.

Shipley, Buford Wiley, Jr.

1991-02-01

14

Error compensation algorithm for patient positioning robotics system  

NASA Astrophysics Data System (ADS)

Surgeons in various medical areas (orthopedic surgery, neurosurgery, dentistry etc.) are using motor-driven drilling tools to make perforations in hard tissues (bone, enamel, dentine, cementum etc.) When the penetration requires very precise angles and accurate alignment with respect to different targets, precision cannot be obtained by using visual estimation and hand-held tools. Robots have been designed to allow for very accurate relative positioning of the patient and the surgical tools, and in certain classes of applications the location of bone target and inclination of the surgical tool can be accurately specified with respect to an inertial frame of reference. However, patient positioning errors as well as position changes during surgery can jeopardize the precision of the operation, and drilling parameters have to be dynamically adjusted. In this paper the authors present a quantitative method to evaluate the corrected position and inclination of the drilling tool, to account for translational and rotational errors in displaced target position. The compensation algorithm applies principles of inverse kinematics wherein a faulty axis in space caused by the translational and rotational errors of the target position is identified with an imaginary true axis in space by enforcing identity through a modified trajectory. In the absence of any specific application, this algorithm is verified on Solid Works, a commercial CAD tool and found to be correct. An example problem given at the end vindicates this statement.

Murty, Pilaka V.; Talpasanu, Ilie; Roz, Mugur A.

2009-03-01

15

Lateral location error compensation algorithm for measuring aspheric surfaces by sub-aperture stitching interferometry  

NASA Astrophysics Data System (ADS)

Sub-aperture stitching (SAS) testing method is an effective way to extend the lateral and vertical dynamic range of a conventional interferometer. However, the center of each sub-aperture could be in error because of the complex motion of the mechanical platform. To eliminate the affection of lateral location error in the final stitching result, a lateral location error compensation algorithm is introduced and the ability of the algorithm to compensate the lateral location error is analyzed. Finally, a 152.4mm concave parabolic mirror is tested using SAS method with the compensation algorithm. The result showed that the algorithm can effectively compensate the lateral location error caused by the mechanical motion. The proposal of the algorithm can reduce high requirement of mechanical platform, which provides a feasible method for the practical application of the engineering.

Zhao, Zixin; Zhao, Hong; Gu, Feifei; Zhang, Lu

2013-04-01

16

Contact Friction Compensation for Robots Using Genetic Learning Algorithms  

Microsoft Academic Search

In this paper, the issues of contact friction compensation for constrained robots are presented. The proposed design consists of two loops. The inner loop is for the inverse dynamics control which linearizes the system by canceling nonlinear dynamics, while the outer loop is for friction compensation. Although various models of friction have been proposed in many engineering applications, frictional force

Der-cherng Liaw; Jeng-Tze Huang

1998-01-01

17

Atmospheric compensation in the presence of clouds: an adaptive empirical line method (AELM) approach  

NASA Astrophysics Data System (ADS)

Many algorithms exist to invert airborne imagery from units of either radiance or sensor specific digital counts to units of reflectance. These compensation algorithms remove unwanted atmospheric variability allowing objects on the ground to be analyzed. Low error levels in homogenous atmospheric conditions have been demonstrated. In many cases however, clouds are present in the atmosphere which introduce error into the inversion at unacceptable levels. For example, the relationship that is defined between sensor reaching radiance and ground reflectance in a cloud free scene will not be the same as in an adjacent region with clouds in the surround. A novel method has been developed which utilizes ground based measurements to modify the empirical line method (ELM) approach on a per-pixel basis. A physics based model of the atmosphere is used to generate a spatial correction for the ELM. Creation of this model is accomplished by analyzing whole-sky imagery to produce a cloud mask which drives input parameters to the radiative transfer (RT) code MODTRAN. The RT code is run for several different azimuth and zenith orientations to create a three-dimensional representation of the hemisphere. The model is then used to achieve a per-pixel correction by adjusting the ELM slope spatially. This method is applied to real data acquired over the atmospheric radiation measurement (ARM) site in Lamount, OK. Performance of the method is evaluated with the Hyperspectral Digital Imagery Collection Experiment (HYDICE) instrument. The sensitivity to spectral sampling is also assessed by down-sampling the HYDICE data to the spectral response of the multi-spectral system Wildfire Airborne Sensor Program LITE (WASP Lite). Finally a method to utilize this approach when additional sensors (like a sky camera) are not available is suggested.

Bartlett, Brent; Schott, John R.

2009-02-01

18

Compensation Algorithms Applied to Power Quality conditioners in three-phase four-wire systems  

Microsoft Academic Search

This work presents compensation algorithm schemes used in power quality conditioners applied to three-phase four-wire systems, allowing harmonic current suppression and reactive power compensation which results in an effective power factor correction. The strategies used to extract the three-phase compensation currents are based on the synchronous reference frame method. Although this method is itself based on balanced three-phase loads, it

Sergio A. Oliveira da Silva; R. A. Modesto; A. Goedtel; C. F. Nascimento

2010-01-01

19

Adaptive PMD compensation using DPSO algorithm for high-speed optical fibre communication systems  

Microsoft Academic Search

We proposed an adaptive PMD compensation scheme based on FPGA using DPSO algorithm. Stable polarization compensation for 43Gbit\\/s RZ-DQPSK transmission over 1200km was demonstrated with endless polarization scrambling. Excellent performance was accomplished utilizing our scheme in case of changing SOP and DGD in longhaul fibre link.

Jinnan Zhang; Yangan Zhang; Xuan Weng; Xueguang Yuan; Mi Lin; Tao Jinjing; Xiaoguang Zhang

2010-01-01

20

Adaptive PMD compensation using DPSO algorithm for high-speed optical fibre communication systems  

Microsoft Academic Search

We proposed an adaptive PMD compensation scheme based on FPGA using DPSO algorithm. Stable polarization compensation for 43 Gbit\\/s RZ-DQPSK transmission over 1200 km was demonstrated with endless polarization scrambling. Excellent performance was accomplished utilizing our scheme in case of changing SOP and DGD in long-haul fibre link.

Jinnan Zhang; Yangan Zhang; Xuan Weng; Xueguang Yuan; Mi Lin; Tao Jinjing; Xiaoguang Zhang

2010-01-01

21

Performance assessment of ACORN atmospheric correction algorithm  

NASA Astrophysics Data System (ADS)

The ACORN atmospheric correction routine was evaluated using criteria established in a precious performance assessment effort. The data utilized in this analysis represented a variety of background and atmospheric conditions, and were collected by the HYDICE imaging spectrometer. The baseline technique used to match retrieved reflectance spectra with ground truth was the matched filter with the bad bands deleted. Additional investigations were conducted to examine the effects on performance when the spectral angle mapper and the mixture tuned matched filter algorithms were used in place of the matched filter and when different numbers of bands were employed during spectral matching. Results substantiated the conclusions drawn from the previous study that the empirical line method ground truth-based atmospheric correction technique generally out-performs existing model-based techniques, such as ACORN.

Miller, Craig J.

2002-08-01

22

Adaptive optics compensation of multiple orbital angular momentum beams propagating through emulated atmospheric turbulence.  

PubMed

We propose an adaptive optics compensation scheme to simultaneously compensate multiple orbital angular momentum (OAM) beams propagating through atmospheric turbulence. A Gaussian beam on one polarization is used to probe the turbulence-induced wavefront distortions and derive the correction pattern for compensating the OAM beams on the orthogonal polarization. By using this scheme, we experimentally demonstrate simultaneous compensation of multiple OAM beams, each carrying a 100??Gbit/s data channel through emulated atmospheric turbulence. The experimental results indicate that the correction pattern obtained from the Gaussian probe beam could be used to simultaneously compensate multiple turbulence-distorted OAM beams with different orders. It is found that the turbulence-induced crosstalk effects on neighboring modes are efficiently reduced by 12.5dB, and the system power penalty is improved by 11dB after compensation. PMID:24978218

Ren, Yongxiong; Xie, Guodong; Huang, Hao; Bao, Changjing; Yan, Yan; Ahmed, Nisar; Lavery, Martin P J; Erkmen, Baris I; Dolinar, Samuel; Tur, Moshe; Neifeld, Mark A; Padgett, Miles J; Boyd, Robert W; Shapiro, Jeffrey H; Willner, Alan E

2014-05-15

23

Atmospheric correction algorithm for hyperspectral imagery  

NASA Astrophysics Data System (ADS)

In December 1997, the U.S. Department of Energy (DOE) established a Center of Excellence (Hyperspectral- Multispectral Algorithm Research Center, HyMARC) for promoting the research and development of algorithms to exploit spectral imagery. This center is located at the DOE Remote Sensing Laboratory in Las Vegas, Nevada, and is operated for the DOE by Bechtel Nevada. This paper presents the results to date of a research project begun at the center during 1998 to investigate the correction of hyperspectral data for atmospheric aerosols. Results of a project conducted by the Rochester Institute of Technology to define, implement, and test procedures for absolute calibration and correction of hyperspectral data to absolute units of high spectral resolution imagery will be presented. Hybrid techniques for atmospheric correction using image or spectral scene data coupled through radiative propagation models will be specifically addressed. Results of this effort to analyze HYDICE sensor data will be included. Preliminary results based on studying the performance of standard routines, such as Atmospheric Pre-corrected Differential Absorption and Nonlinear Least Squares Spectral Fit, in retrieving reflectance spectra show overall reflectance retrieval errors of approximately one to two reflectance units in the 0.4- to 2.5-micron-wavelength region (outside of the absorption features). The results are based on HYDICE sensor data collected from the Southern Great Plains Atmospheric Radiation Measurement site during overflights conducted in July of 1997. Results of an upgrade made in the model-based atmospheric correction techniques, which take advantage of updates made to the moderate resolution atmospheric transmittance model (MODTRAN 4.0) software, will also be presented. Data will be shown to demonstrate how the reflectance retrievals in the shorter wavelengths of the blue-green region will be improved because of enhanced modeling of multiple scattering effects.

Sanders, Lee C.; Raqueno, Rolando V.; Schott, John R.

1999-12-01

24

Atmospheric Correction Algorithm for Hyperspectral Imagery  

SciTech Connect

In December 1997, the US Department of Energy (DOE) established a Center of Excellence (Hyperspectral-Multispectral Algorithm Research Center, HyMARC) for promoting the research and development of algorithms to exploit spectral imagery. This center is located at the DOE Remote Sensing Laboratory in Las Vegas, Nevada, and is operated for the DOE by Bechtel Nevada. This paper presents the results to date of a research project begun at the center during 1998 to investigate the correction of hyperspectral data for atmospheric aerosols. Results of a project conducted by the Rochester Institute of Technology to define, implement, and test procedures for absolute calibration and correction of hyperspectral data to absolute units of high spectral resolution imagery will be presented. Hybrid techniques for atmospheric correction using image or spectral scene data coupled through radiative propagation models will be specifically addressed. Results of this effort to analyze HYDICE sensor data will be included. Preliminary results based on studying the performance of standard routines, such as Atmospheric Pre-corrected Differential Absorption and Nonlinear Least Squares Spectral Fit, in retrieving reflectance spectra show overall reflectance retrieval errors of approximately one to two reflectance units in the 0.4- to 2.5-micron-wavelength region (outside of the absorption features). These results are based on HYDICE sensor data collected from the Southern Great Plains Atmospheric Radiation Measurement site during overflights conducted in July of 1997. Results of an upgrade made in the model-based atmospheric correction techniques, which take advantage of updates made to the moderate resolution atmospheric transmittance model (MODTRAN 4.0) software, will also be presented. Data will be shown to demonstrate how the reflectance retrieval in the shorter wavelengths of the blue-green region will be improved because of enhanced modeling of multiple scattering effects.

R. J. Pollina

1999-09-01

25

A Comprehensive Study of Three Delay Compensation Algorithms for Flight Simulators  

NASA Technical Reports Server (NTRS)

This paper summarizes a comprehensive study of three predictors used for compensating the transport delay in a flight simulator; The McFarland, Adaptive and State Space Predictors. The paper presents proof that the stochastic approximation algorithm can achieve the best compensation among all four adaptive predictors, and intensively investigates the relationship between the state space predictor s compensation quality and its reference model. Piloted simulation tests show that the adaptive predictor and state space predictor can achieve better compensation of transport delay than the McFarland predictor.

Guo, Liwen; Cardullo, Frank M.; Houck, Jacob A.; Kelly, Lon C.; Wolters, Thomas E.

2005-01-01

26

Comparison of texture coding algorithm in a unified motion prediction/compensation video compression algorithm  

NASA Astrophysics Data System (ADS)

Efficient video compression is based on three principles: reduction of the temporal, spatial and statistical redundancy present in the video signal. Most video compression algorithm, (MPEGs, H.26x, ...) use the same principle to reduce the spatial redundancy, i.e. an 8x8 DCT transform. However there exist other transforms capable of similar results. Those are the integer 4x4 DCT and the wavelet transforms for instance. This article compare many transforms in the same global compression scheme, i.e the same motion estimation, compensation strategy and the same entropy coding. Moreover the tests are conducted on sequences of different nature, such as sport, video surveillance and movies. This allows a global performance comparison of those transforms in many different scenarios.

Reichel, Julien; Ziliani, Francesco

2003-06-01

27

Phase compensating algorithm investigation of real-time adaptive femtosecond pulse shaping  

NASA Astrophysics Data System (ADS)

Based on the real-time adaptive femtosecond pulse shaping system, the phase compensating algorithms which can effectively compensate the output shaping waveform distortions are investigated in detail. The simulated-annealing algorithm that can modify the output pulse temporal waveforms iteratively toward the target shapes using the second harmonic generating frequency resolved optical gating (SHG-FROG) measurement as feedback is proposed. Compared with the cross-correlation feedback measurement method, the output based on the SHG-FROG measurement method is better and the temporal chirp of the output pulse is compensated more effectively. Moreover the performance of the SHG-FROG measurement feedback algorithm is compared to other exemplary standard approaches such as the Genetic Algorithm based on the cross-correlation feedback measurement method, the result is much better.

Lou, Xin; Sun, Tie-ju; Duan, Fang-zhen; Yang, Xue-hua; Nie, Yong-ming

2013-09-01

28

A Novel Online Mutual Coupling Compensation Algorithm for Uniform and Linear Arrays  

Microsoft Academic Search

In this paper, a novel online mutual coupling compensation algorithm especially tailored to uniform and linear arrays is presented. It is conceived to simultaneously compensate for mutual coupling and estimate the direction-of-arrivals (DOAs) of signals impinging on the array since the estimated calibration matrix can be embedded within any classical super-resolution direction-finding method. An alternating minimization procedure based on closed-form

Fabrizio Sellone; Alberto Serra

2007-01-01

29

Adaptive filter design based on the LMS algorithm for delay elimination in TCR/FC compensators.  

PubMed

Thyristor controlled reactor with fixed capacitor (TCR/FC) compensators have the capability of compensating reactive power and improving power quality phenomena. Delay in the response of such compensators degrades their performance. In this paper, a new method based on adaptive filters (AF) is proposed in order to eliminate delay and increase the response of the TCR compensator. The algorithm designed for the adaptive filters is performed based on the least mean square (LMS) algorithm. In this design, instead of fixed capacitors, band-pass LC filters are used. To evaluate the filter, a TCR/FC compensator was used for nonlinear and time varying loads of electric arc furnaces (EAFs). These loads caused occurrence of power quality phenomena in the supplying system, such as voltage fluctuation and flicker, odd and even harmonics and unbalancing in voltage and current. The above design was implemented in a realistic system model of a steel complex. The simulation results show that applying the proposed control in the TCR/FC compensator efficiently eliminated delay in the response and improved the performance of the compensator in the power system. PMID:21193194

Hooshmand, Rahmat Allah; Torabian Esfahani, Mahdi

2011-04-01

30

Free breathing myocardial perfusion data sets for performance analysis of motion compensation algorithms  

PubMed Central

Background Perfusion quantification by using first-pass gadolinium-enhanced myocardial perfusion magnetic resonance imaging (MRI) has proved to be a reliable tool for the diagnosis of coronary artery disease that leads to reduced blood flow to the myocardium. The image series resulting from such acquisition usually exhibits a breathing motion that needs to be compensated for if a further automatic analysis of the perfusion is to be executed. Various algorithms have been presented to facilitate such a motion compensation, but the lack of publicly available data sets hinders a proper, reproducible comparison of these algorithms. Material Free breathing perfusion MRI series of ten patients considered clinically to have a stress perfusion defect were acquired; for each patient a rest and a stress study was executed. Manual segmentations of the left ventricle myocardium and the right-left ventricle insertion point are provided for all images in order to make a unified validation of the motion compensation algorithms and the perfusion analysis possible. In addition, all the scripts and the software required to run the experiments are provided alongside the data, and to enable interested parties to directly run the experiments themselves, the test bed is also provided as a virtual hard disk. Findings To illustrate the utility of the data set two motion compensation algorithms with publicly available implementations were applied to the data and earlier reported results about the performance of these algorithms could be confirmed. Conclusion The data repository alongside the evaluation test bed provides the option to reliably compare motion compensation algorithms for myocardial perfusion MRI. In addition, we encourage that researchers add their own annotations to the data set, either to provide inter-observer comparisons of segmentations, or to make other applications possible, for example, the validation of segmentation algorithms. PMID:25392734

2014-01-01

31

An NN-Based SRD Decomposition Algorithm and Its Application in Nonlinear Compensation.  

PubMed

In this study, a neural network-based square root of descending (SRD) order decomposition algorithm for compensating for nonlinear data generated by sensors is presented. The study aims at exploring the optimized decomposition of data 1.00,0.00,0.00 and minimizing the computational complexity and memory space of the training process. A linear decomposition algorithm, which automatically finds the optimal decomposition N and reduces the training time to 1 N and memory cost to 1 N has been implemented on nonlinear data obtained from an encoder. Particular focus is given to the theoretical access of estimating the numbers of hidden nodes and the precision of varying the decomposition method. Numerical experiments are designed to evaluate the effect of this algorithm. Moreover, a designed device for angular sensor calibration is presented. We conduct an experiment that samples the data of an encoder and compensates for the nonlinearity of the encoder to testify this novel algorithm. PMID:25232912

Yan, Honghang; Deng, Fang; Sun, Jian; Chen, Jie

2014-01-01

32

An NN-Based SRD Decomposition Algorithm and Its Application in Nonlinear Compensation  

PubMed Central

In this study, a neural network-based square root of descending (SRD) order decomposition algorithm for compensating for nonlinear data generated by sensors is presented. The study aims at exploring the optimized decomposition of data 1.00,0.00,0.00 and minimizing the computational complexity and memory space of the training process. A linear decomposition algorithm, which automatically finds the optimal decomposition of N subparts and reduces the training time to 1N and memory cost to 1N, has been implemented on nonlinear data obtained from an encoder. Particular focus is given to the theoretical access of estimating the numbers of hidden nodes and the precision of varying the decomposition method. Numerical experiments are designed to evaluate the effect of this algorithm. Moreover, a designed device for angular sensor calibration is presented. We conduct an experiment that samples the data of an encoder and compensates for the nonlinearity of the encoder to testify this novel algorithm. PMID:25232912

Yan, Honghang; Deng, Fang; Sun, Jian; Chen, Jie

2014-01-01

33

TIGER: Development of Thermal Gradient Compensation Algorithms and Techniques  

NASA Technical Reports Server (NTRS)

In a wind tunnel facility, the direct measurement of forces and moments induced on the model are performed by a force measurement balance. The measurement balance is a precision-machined device that has strain gages at strategic locations to measure the strain (i.e., deformations) due to applied forces and moments. The strain gages convert the strain (and hence the applied force) to an electrical voltage that is measured by external instruments. To address the problem of thermal gradients on the force measurement balance NASA-LaRC has initiated a research program called TIGER - Thermally-Induced Gradients Effects Research. The ultimate goals of the TIGER program are to: (a) understand the physics of the thermally-induced strain and its subsequent impact on load measurements and (b) develop a robust thermal gradient compensation technique. This paper will discuss the impact of thermal gradients on force measurement balances, specific aspects of the TIGER program (the design of a special-purpose balance, data acquisition and data analysis challenges), and give an overall summary.

Hereford, James; Parker, Peter A.; Rhew, Ray D.

2004-01-01

34

Multiangle implementation of atmospheric correction (MAIAC): 2. Aerosol algorithm  

Microsoft Academic Search

An aerosol component of a new multiangle implementation of atmospheric correction (MAIAC) algorithm is presented. MAIAC is a generic algorithm developed for the Moderate Resolution Imaging Spectroradiometer (MODIS), which performs aerosol retrievals and atmospheric correction over both dark vegetated surfaces and bright deserts based on a time series analysis and image-based processing. The MAIAC look-up tables explicitly include surface bidirectional

A. Lyapustin; Y. Wang; I. Laszlo; R. Kahn; S. Korkin; L. Remer; R. Levy; J. S. Reid

2011-01-01

35

Low complexity motion estimation algorithm by multiresolution search for long-term memory motion compensation  

Microsoft Academic Search

We propose a new low complexity motion estimation (ME) algo- rithm using multiresolution motion search for long term memory motion compensation (LTMC, (1)). While multiresolution motion search has been used for standard single-frame motion compensa- tion, here we introduce several novel techniques to exploit it effi- ciently in the context of LTMC. The proposed algorithm computes a coarse motion vector

Hyukjune Chung; Antonio Ortega; Yutaka Horiguchi

2002-01-01

36

A fast atmospheric correction algorithm applied to Landsat TM images  

Microsoft Academic Search

A fast atmospheric correction algorithm for the reflective bands (0.4-2.5 microns) of remote sensing instruments is presented. It proceeds in two steps: calculation of the ground reflectance of each pixel based on precomputed planetary albedo functions for different standard atmospheres, aerosol types and optical depths, or actual atmospheric measurement data, and approximate correction of the adjacency effect by taking into

Rudolf Richter

1990-01-01

37

Compensation of atmospheric CO2 buildup through engineered chemical sinkage  

NASA Astrophysics Data System (ADS)

Retrieval of background carbon dioxide into regional chemical extractors would counter anthropogenic inputs in a manner friendly to established industries. We demonstrate via atmospheric transport/scaling calculations that for idealized flat removal units, global coverage could be less than two hundred thousand square kilometers. The disrupted area drops to a small fraction of this with engineering into the vertical to bypass laminarity. Fence structures and artificial roughness elements can both be conceived. Sink thermodynamics are analyzed by taking calcium hydroxide as a sample reactant. Energy costs could be minimized at near the endothermicity of binding reversal. In the calcium case the value is 25 kcal mole-1, as against a fuel carbon content of 150 in the same units. Aqueous kinetics are less than favorable for the hydroxide, but misting could counteract slow liquid phase transfer. Properties of superior scrubbers are outlined.

Elliott, S.; Lackner, K. S.; Ziock, H. J.; Dubey, M. K.; Hanson, H. P.; Barr, S.; Ciszkowski, N. A.; Blake, D. R.

38

Validation and Error Metrics for the Atmospheric Compensation for a Landsat Land Surface Temperature Product  

NASA Astrophysics Data System (ADS)

An automated process for the atmospheric compensation for a Landsat land surface temperature product has been developed. Landsat data are very attractive for a global land surface temperature product because the spatial and temporal resolution and range of the imagery make them well matched to applications for the study of agriculture, the environment, weather, and climate among others. However, Landsat's single thermal band requires per-pixel atmospheric compensation and emissivity; this work focuses on the atmospheric compensation aspect of the process and will be integrated with ASTER derived emissivity data to output a land surface temperature product. For the same reasons Landsat is attractive, an automated atmospheric compensation technique is challenging; it requires atmospheric characterization over a large area and long time scale at an acceptable resolution. Using North American Regional Reanalysis (NARR) data, MODTRAN radiative transfer code, and a number of interpolation techniques, a tool has been developed to generate the necessary radiative transfer parameters at each pixel for any radiometrically calibrated North American Landsat scene in the archive. Initial validation of predicted temperatures using ground truth water temperatures from platforms and buoys verifies the fidelity of the process with good performance when the atmosphere is accurately characterized. However, performance is poorer when the composition of the atmosphere is not as well understood. Because of the desired automation and extent of the tool, we are limited in the availability of acceptable atmospheric profile data. The goal is to understand sources of error in order to predict and characterize the uncertainty in the retrieved temperatures. While the performance has been extensively tested using a number of NOAA buoys with bulk temperature measurements corrected to skin temperature, traditional error analysis is complicated by the atmospheric reanalysis, radiative transfer codes, bulk to skin temperature conversion, and lack of knowledge of atmospheric variations not captured by the reanalysis data, so current work focuses on developing and comparing different methods of error prediction. Characterizing errors in the input atmospheric profiles, regression techniques against current error values, and thresholds based on known atmospheric variables have all been considered. The goal is to utilize a hybrid approach to generate a confidence for each pixel in the final product that will provide the user with metrics that predict the expected performance with a range of confidence scores.

Cook, M. J.; Schott, J. R.

2013-12-01

39

Iterative reconstruction methods in atmospheric tomography: FEWHA, Kaczmarz and Gradient-based algorithm  

NASA Astrophysics Data System (ADS)

The problem of atmospheric tomography arises in ground-based telescope imaging with adaptive optics (AO), where one aims to compensate in real-time for the rapidly changing optical distortions in the atmosphere. Many of these systems depend on a sufficient reconstruction of the turbulence profiles in order to obtain a good correction. Due to steadily growing telescope sizes, there is a strong increase in the computational load for atmospheric reconstruction with current methods, first and foremost the MVM. In this paper we present and compare three novel iterative reconstruction methods. The first iterative approach is the Finite Element- Wavelet Hybrid Algorithm (FEWHA), which combines wavelet-based techniques and conjugate gradient schemes to efficiently and accurately tackle the problem of atmospheric reconstruction. The method is extremely fast, highly flexible and yields superior quality. Another novel iterative reconstruction algorithm is the three step approach which decouples the problem in the reconstruction of the incoming wavefronts, the reconstruction of the turbulent layers (atmospheric tomography) and the computation of the best mirror correction (fitting step). For the atmospheric tomography problem within the three step approach, the Kaczmarz algorithm and the Gradient-based method have been developed. We present a detailed comparison of our reconstructors both in terms of quality and speed performance in the context of a Multi-Object Adaptive Optics (MOAO) system for the E-ELT setting on OCTOPUS, the ESO end-to-end simulation tool.

Ramlau, R.; Saxenhuber, D.; Yudytskiy, M.

2014-07-01

40

Fourier algorithm method for reconstruction of large-aperture digital holograms based on phase compensation.  

PubMed

To simplify the reconstruction calculation of a large-aperture digital hologram we propose a novel Fourier-transformation reconstruction algorithm. When the reconstructed wave is the same as or similar to the reference wave, the higher-order phase term of reconstruction can be compensated for. For example, the variation between the higher-order phase term and the aperture angle with a different field of view in in-line phase-shifting digital holography is analyzed. PMID:15035488

Lu, Xiaoxu; Zhang, Yimo; Zhong, Liyun; Luo, Yinlong; She, Canling

2004-03-15

41

Atmospheric Correction Algorithm for Hyperspectral Imagery  

Microsoft Academic Search

In December 1997, the US Department of Energy (DOE) established a Center of Excellence (Hyperspectral-Multispectral Algorithm Research Center, HyMARC) for promoting the research and development of algorithms to exploit spectral imagery. This center is located at the DOE Remote Sensing Laboratory in Las Vegas, Nevada, and is operated for the DOE by Bechtel Nevada. This paper presents the results to

R. J. Pollina

1999-01-01

42

Atmospheric correction algorithm for hyperspectral imagery  

Microsoft Academic Search

In December 1997, the U.S. Department of Energy (DOE) established a Center of Excellence (Hyperspectral- Multispectral Algorithm Research Center, HyMARC) for promoting the research and development of algorithms to exploit spectral imagery. This center is located at the DOE Remote Sensing Laboratory in Las Vegas, Nevada, and is operated for the DOE by Bechtel Nevada. This paper presents the results

Lee C. Sanders; Rolando V. Raqueno; John R. Schott

1999-01-01

43

A fast algorithm for DCT-domain inverse motion compensation based on shared information in a macroblock  

Microsoft Academic Search

The ability to construct intracoded frame from motion-compensated intercoded frames directly in the com- pressed domain is important for efficient video manipulation and composition. In the context of motion-compensated discrete cosine transform (DCT)-based coding of video as in MPEG video, this problem of DCT-domain inverse motion compensation has been studied and, subsequently, improved faster algorithms were proposed. These schemes, however,

Junehwa Song; Boon-lock Yeo

2000-01-01

44

The Results of a Simulator Study to Determine the Effects on Pilot Performance of Two Different Motion Cueing Algorithms and Vario us Delays, Compensated and Uncompensated  

Microsoft Academic Search

A s tudy was conducted employing the Visual Motion Simulator (VMS) at the NASA Langley Research Center, Hampton, Virginia. This study compared two motion cueing algorithms, the NASA adaptive algorithm and a new optimal control based algorithm. Also, the study included the effects of transport delays and the compensation thereof. The delay compensation algorithm employed is one developed by Richard

Liwen Guo; Frank M. Cardullo; Robert J. Telban; Jacob A. Houck; Unisys Corp

45

The algorithm of regionally compensating nonlinear response of photo detector to improve the quality of image reconstruction for compressed sensing  

NASA Astrophysics Data System (ADS)

In imaging systems based on compressed sensing, error in the measured data is incurred due to the nonlinear response of the photo-detector, which affects the quality of reconstructed images. Conventionally, the affected measured data will be eliminated in order to obtain the high reconstruction quality. However, when there are too many measured data affected, it is impossible to reject all such data which will certainly degrade the imaging efficiency. Therefore, an algorithm of regionally compensating the non-linear response from the detector is proposed. The nonlinear measured data will be compensated but not rejected in the proposed algorithm. According to the detector response curve, all of the nonlinear measured data will be divided into several parts. The data in the same part will have the same average compensation factor which can be obtained from the response curve after calculation. The affected measured data will be compensated with the compensation factor regionally before used to reconstruct the original image. The theoretical analysis and simulation results show that a reconstructed image with high quality can still be obtained even when over 80% of the measured data are nonlinear. It is impossible to get such a high quality reconstructed image with the conventionally algorithm. The PSNR and the M-rate in the simulation show that the compensation algorithm can greatly deal with the situation of too many nonlinear measured data.

Zhuang, Jiayan; Chen, Qian; Miao, Zhuang; He, Weiji; Feng, Weiyi

2013-08-01

46

Simulation of atmospheric turbulence compensation through piston-only phase control of a laser phased array  

NASA Astrophysics Data System (ADS)

Beam propagation from a laser phased array system through the turbulent atmosphere is simulated and the ability of such a system to compensate for the atmosphere via piston-only phase control of the sub-apertures is evaluated. Directed energy (DE) applications demand more power than most lasers can produce, consequently many schemes for high power involve combining the beams from many smaller lasers into one. When many smaller lasers are combined into a phased array, phase control of the individual sub-apertures will be necessary to create a high-quality beam. Phase control of these sub-apertures could then be used to do more, such as focus, steer, and compensate for atmospheric turbulence. Atmospheric turbulence is well known to degrade the performance of both imaging systems and laser systems. Adaptive optics can be used to mitigate this degradation. Adaptive optics ordinarily involves a deformable mirror, but with phase control on each sub-aperture the need for a deformable mirror is eliminated. The simulation conducted here evaluates performance gain for a 127 element phased array in a hexagonal pattern with piston-only phase control on each element over an uncompensated array for varying levels of atmospheric turbulence. While most simulations were carried out against a 10 km tactical scenario, the turbulence profile was adjusted so performance could be evaluated as a function of the Fried Parameter (r0) and the log-amplitude variance somewhat independently. This approach is demonstrated to be generally effective with the largest percentage improvement occurring when r0 is close to the sub-aperture diameter.

McCrae, Jack E.; Van Zandt, Noah; Cusumano, Salvatore J.; Fiorino, Steven T.

2013-05-01

47

An efficient multiresolution algorithm for compensating density-dependent media blurring  

NASA Astrophysics Data System (ADS)

The sharpness of a printed image may suffer due to the presence of material layers above and below the dye layers. These layers contribute to scattering and surface reflections that make the degradation in sharpness density-dependent. We present data that illustrate this effect, and model the phenomenon numerically. A digital non-linear sharpening filter is proposed to compensate for this density-dependent blurring. The support and shape of this filter is constrained to lie in a space spanned by a set of basis filters that can be computed efficiently. Burt and Adelson's Laplacian pyramid is used to develop an efficient scale-recursive algorithm in which the image is decomposed into the high-pass basis images in a fine-to-coarse scale sweep, and the sharpened image along with a local density image is subsequently synthesized by a coarse-to-fine scale sweep using these basis images. The local density image is employed, in combination with a scale dependent gain function, to modulate the high-pass basis images in a space-varying fashion. A robust method is proposed for the estimation of the gain functions directly from measured data. Experimental results demonstrate that the proposed algorithm successfully compensates for media-related density dependent blurring.

Saquib, Suhail S.; Vetterling, William T.

2005-03-01

48

The effects of atmospheric turbulence on precision optical measurements used for antenna-pointing compensation  

NASA Technical Reports Server (NTRS)

Blind pointing of the Deep Space Network (DSN) 70-meter antennas can be improved if distortions of the antenna structure caused by unpredictable environmental loads can be measured in real-time, and the resulting boresight shifts evaluated and incorporated into the pointing control loops. The measurement configuration of a proposed pointing compensation system includes an optical range sensor that measures distances to selected points on the antenna surface. The effect of atmospheric turbulence on the accuracy of optical distance measurements and a method to make in-situ determinations of turbulence-induced measurement errors are discussed.

Nerheim, N.

1989-01-01

49

Validation of the Atmospheric Infrared Sounder radiative transfer algorithm  

Microsoft Academic Search

Comparisons between observed AIRS radiances and radiances computed from coincident in situ profile data are used to validate the accuracy of the AIRS radiative transfer algorithm (RTA) used in version 4 processing at Goddard Space Flight Center. In situ data sources include balloon-borne measurements with RS-90 sensors and frost point hygrometers and Raman lidar measurements of atmospheric water vapor. Estimates

L. L. Strow; S. E. Hannon; S. De-Souza Machado; H. E. Motteler; D. C. Tobin

2006-01-01

50

New algorithm for atmospheric correction of hyperspectral remote sensing data  

Microsoft Academic Search

We previously developed an algorithm for remote sensing of ocean color from space that allows quick atmospheric correction of hyperspectral data using lookup tables generated with a modified version of Ahmad & Fraser's vector radiative transfer code. During the past year we extended our radiative transfer calculations, allowing us to generate tables for several airborne altitudes. We also modified our

Marcos J. Montes; Bo-Cai Gao; Curtiss O. Davis

2001-01-01

51

Algorithm for Atmospheric Corrections of Aircraft and Satellite Imagery  

NASA Technical Reports Server (NTRS)

A simple and fast atmospheric correction algorithm is described which is used to correct radiances of scattered sunlight measured by aircraft and/or satellite above a uniform surface. The atmospheric effect, the basic equations, a description of the computational procedure, and a sensitivity study are discussed. The program is designed to take the measured radiances, view and illumination directions, and the aerosol and gaseous absorption optical thickness to compute the radiance just above the surface, the irradiance on the surface, and surface reflectance. Alternatively, the program will compute the upward radiance at a specific altitude for a given surface reflectance, view and illumination directions, and aerosol and gaseous absorption optical thickness. The algorithm can be applied for any view and illumination directions and any wavelength in the range 0.48 micron to 2.2 micron. The relation between the measured radiance and surface reflectance, which is expressed as a function of atmospheric properties and measurement geometry, is computed using a radiative transfer routine. The results of the computations are presented in a table which forms the basis of the correction algorithm. The algorithm can be used for atmospheric corrections in the presence of a rural aerosol. The sensitivity of the derived surface reflectance to uncertainties in the model and input data is discussed.

Fraser, Robert S.; Kaufman, Yoram J.; Ferrare, Richard A.; Mattoo, Shana

1989-01-01

52

Heterogeneity of SPECT bull`s-eyes in normal dogs: Comparison of attenuation compensation algorithms  

SciTech Connect

In normal dogs, SPECT {sup 99m}Tc Sestamibi (MIBI) and {sup 201}Tl myocardial perfusion images reconstructed with filtered backprojection (FBP) show a large decrease of counts in the septal wall (S) compared to the lateral wall (L). The authors evaluated the iterative method of Chang at 0 and 1 iterations (Chang0 and Chang1), and the Maximum Likelihood-Expectation Maximization with attenuation compensation (ML-EM-ATN) algorithm on data acquired from 5 normal dogs and from simulated projection data using a homogeneous count-density model of a normal canine myocardium in the attenuation field measured in one dog. Mean counts in the S and L regions were calculated from maximum-count circumferential profile arrays. Their results demonstrate that ML-EM-ATN and Chang1 result in improved uniformity, as measured by the S/L ratio.

DiBella, E.V.R.; Eisner, R.L.; Schmarkey, L.S.; Barclay, A.B.; Patterson, R.E.; Nowak, D.J.; Lalush, D.S.; Tsui, B.M.W. [Georgia Inst. of Technology, Atlanta, GA (United States). Dept. of Electrical Engineering] [Georgia Inst. of Technology, Atlanta, GA (United States). Dept. of Electrical Engineering; [Emory Univ., Atlanta, GA (United States). Crawford Long Hospital; [Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Biomedical Engineering

1995-08-01

53

Atmospheric correction algorithm for CHRIS images application to CASI  

NASA Astrophysics Data System (ADS)

The Compact High Resolution Imaging Spectrometer CHRIS sensor was launched on board of PROBA (PROject for on Board Autonomy) the 22nd of October 2001. CHRIS will acquire sets of images over the Belgian coastal zone near Oostende. Within this context CASI (Compact Airborne Spectrographic Imager) images was used as prototype of CHRIS data. This is to assess the performance of an atmospheric correction algorithm for hyperspectral ocean-color sensors (i.e. CHRIS). This approach couples the atmospheric attenuation processes with the underlying physics of water inherent optical properties. The algorithm employed the 6S code (second simulation of the satellite signal in the solar spectrum) to simulate the atmospheric and surface reflectance and the gaseous transmittances. Relationships between the water leaving reflectances at 860 870 and 880 nm are proposed. This is to estimate the water signals at these near infrared (NIR) bands, hence the aerosol reflectances. These negligible water-leaving signals were found to be very important for a reliable atmospheric-correction-algorithm over turbid waters. The choice of this NIR part of the spectrum was to satisfy a certain condition related to the corresponding water absorption coefficient. A look-up-table of total gaseous transmittance has been generated for 42 values of column water vapour. This table was used with a two-band ratio technique to estimate the contribution of water vapour to the total gaseous transmittance. The aerosol optical thicknesses were estimated by fitting calculated atmospheric reflectances at the water vapour window (860-880 nm) to 20 candidates of maritime aerosol models. The performance of the atmospheric correction is being investigated with other sensors (DASI and ROSIS) and in situ measurements.

Salama, Suhyb; Monbaliu, Jaak

2002-11-01

54

New algorithm for atmospheric correction of hyperspectral remote sensing data  

NASA Astrophysics Data System (ADS)

We previously developed an algorithm for remote sensing of ocean color from space that allows quick atmospheric correction of hyperspectral data using lookup tables generated with a modified version of Ahmad & Fraser's vector radiative transfer code. During the past year we extended our radiative transfer calculations, allowing us to generate tables for several airborne altitudes. We also modified our lookup-table software to interpolate to sensor altitudes between those specified in the new tables. Here, we present results of atmospheric corrections using the new tables and software on hyperspectral imagery collected with NRL's recent PHILLS instrument and past AVIRIS flights.

Montes, Marcos J.; Gao, Bo-Cai; Davis, Curtiss O.

2001-06-01

55

An Atmospheric Radiosounding Database for Generating Land Surface Temperature Algorithms  

Microsoft Academic Search

A database of global, cloud-free, and atmospheric radiosounding profiles was compiled with the aim of simulating radiometric measurements from satellite-borne sensors in the thermal infrared. The objective of the simulated data is to generate split-window (SW) and dual-angle (DA) algorithms for the retrieval of land surface temperature (LST) from Terra\\/Moderate Resolution Imaging Spectroradiometer (MODIS) and Envisat\\/Advanced Along Track Scanning Radiometer

Joan M. Galve; Csar Coll; Vicente Caselles; Enric Valor

2008-01-01

56

Control algorithms for aerobraking in the Martian atmosphere  

NASA Astrophysics Data System (ADS)

The Analytic Predictor Corrector (APC) and Energy Controller (EC) atmospheric guidance concepts have been adapted to control an interplanetary vehicle aerobraking in the Martian atmosphere. Modifications are made to the APC to improve its robustness to density variations. These modifications include adaptation of a new exit phase algorithm, an adaptive transition velocity to initiate the exit phase, refinement of the reference dynamic pressure calculation and two hybrid density estimation techniques. The modified controller with the hybrid density estimation technique is called the Mars Hybrid Predictor Corrector (MHPC), while the modified controller with a polynomial density estimator is called the Mars Predictor Corrector (MPC). A Lyapunov Steepest Descent Controller (LSDC) is adapted to control the vehicle. The LSDC lacked robustness, so a Lyapunov tracking exit phase algorithm is developed to guide the vehicle along a reference trajectory. The equilibrium glide entry phase is employed for the first part of the trajectory. This algorithm, when using the hybrid density estimation technique to define the reference path, is called te Lyapunov Hybrid Tracking Controller (LHTC). With the polynomial density estimator used to define the reference trajectory, the algorithm is called the Lyapunov Tracking Controller (LTC). The four new controllers are tested usig a six degree of freedom computer simulation to evaluate their robustness.

Shipley, Buford W., Jr.

1991-12-01

57

Control algorithms for aerobraking in the Martian atmosphere  

NASA Astrophysics Data System (ADS)

The Analytic Predictor Corrector (APC) and Energy Controller (EC) atmospheric guidance concepts were adapted to control an interplanetary vehicle aerobraking in the Martian atmosphere. Changes are made to the APC to improve its robustness to density variations. These changes include adaptation of a new exit phase algorithm, an adaptive transition velocity to initiate the exit phase, refinement of the reference dynamic pressure calculation and two improved density estimation techniques. The modified controller with the hybrid density estimation technique is called the Mars Hybrid Predictor Corrector (MHPC), while the modified controller with a polynomial density estimator is called the Mars Predictor Corrector (MPC). A Lyapunov Steepest Descent Controller (LSDC) is adapted to control the vehicle. The LSDC lacked robustness, so a Lyapunov tracking exit phase algorithm is developed to guide the vehicle along a reference trajectory. This algorithm, when using the hybrid density estimation technique to define the reference path, is called the Lyapunov Hybrid Tracking Controller (LHTC). With the polynomial density estimator used to define the reference trajectory, the algorithm is called the Lyapunov Tracking Controller (LTC). These four new controllers are tested using a six degree of freedom computer simulation to evaluate their robustness. The MHPC, MPC, LHTC, and LTC show dramatic improvements in robustness over the APC and EC.

Ward, Donald T.; Shipley, Buford W., Jr.

1991-09-01

58

Control algorithms for aerobraking in the Martian atmosphere  

NASA Technical Reports Server (NTRS)

The Analytic Predictor Corrector (APC) and Energy Controller (EC) atmospheric guidance concepts were adapted to control an interplanetary vehicle aerobraking in the Martian atmosphere. Changes are made to the APC to improve its robustness to density variations. These changes include adaptation of a new exit phase algorithm, an adaptive transition velocity to initiate the exit phase, refinement of the reference dynamic pressure calculation and two improved density estimation techniques. The modified controller with the hybrid density estimation technique is called the Mars Hybrid Predictor Corrector (MHPC), while the modified controller with a polynomial density estimator is called the Mars Predictor Corrector (MPC). A Lyapunov Steepest Descent Controller (LSDC) is adapted to control the vehicle. The LSDC lacked robustness, so a Lyapunov tracking exit phase algorithm is developed to guide the vehicle along a reference trajectory. This algorithm, when using the hybrid density estimation technique to define the reference path, is called the Lyapunov Hybrid Tracking Controller (LHTC). With the polynomial density estimator used to define the reference trajectory, the algorithm is called the Lyapunov Tracking Controller (LTC). These four new controllers are tested using a six degree of freedom computer simulation to evaluate their robustness. The MHPC, MPC, LHTC, and LTC show dramatic improvements in robustness over the APC and EC.

Ward, Donald T.; Shipley, Buford W., Jr.

1991-01-01

59

Nearly arc-length tool path generation and tool radius compensation algorithm research in FTS turning  

NASA Astrophysics Data System (ADS)

In the non-rotational symmetrical microstrcture surfaces generation using turning method with Fast Tool Servo(FTS), non-uniform distribution of the interpolation data points will lead to long processing cycle and poor surface quality. To improve this situation, nearly arc-length tool path generation algorithm is proposed, which generates tool tip trajectory points in nearly arc-length instead of the traditional interpolation rule of equal angle and adds tool radius compensation. All the interpolation points are equidistant in radial distribution because of the constant feeding speed in X slider, the high frequency tool radius compensation components are in both X direction and Z direction, which makes X slider difficult to follow the input orders due to its large mass. Newton iterative method is used to calculate the neighboring contour tangent point coordinate value with the interpolation point X position as initial value, in this way, the new Z coordinate value is gotten, and the high frequency motion components in X direction is decomposed into Z direction. Taking a typical microstructure with 4?m PV value for test, which is mixed with two 70?m wave length sine-waves, the max profile error at the angle of fifteen is less than 0.01?m turning by a diamond tool with big radius of 80?m. The sinusoidal grid is machined on a ultra-precision lathe succesfully, the wavelength is 70.2278?m the Ra value is 22.81nm evaluated by data points generated by filtering out the first five harmonics.

Zhao, Minghui; Zhao, Xuesen; Li, Zengqiang; Sun, Tao

2014-08-01

60

Mars Entry Atmospheric Data System Modelling and Algorithm Development  

NASA Technical Reports Server (NTRS)

The Mars Entry Atmospheric Data System (MEADS) is being developed as part of the Mars Science Laboratory (MSL), Entry, Descent, and Landing Instrumentation (MEDLI) project. The MEADS project involves installing an array of seven pressure transducers linked to ports on the MSL forebody to record the surface pressure distribution during atmospheric entry. These measured surface pressures are used to generate estimates of atmospheric quantities based on modeled surface pressure distributions. In particular, the quantities to be estimated from the MEADS pressure measurements include the total pressure, dynamic pressure, Mach number, angle of attack, and angle of sideslip. Secondary objectives are to estimate atmospheric winds by coupling the pressure measurements with the on-board Inertial Measurement Unit (IMU) data. This paper provides details of the algorithm development, MEADS system performance based on calibration, and uncertainty analysis for the aerodynamic and atmospheric quantities of interest. The work presented here is part of the MEDLI performance pre-flight validation and will culminate with processing flight data after Mars entry in 2012.

Karlgaard, Christopher D.; Beck, Roger E.; OKeefe, Stephen A.; Siemers, Paul; White, Brady; Engelund, Walter C.; Munk, Michelle M.

2009-01-01

61

A Novel Modified Omega-K Algorithm for Synthetic Aperture Imaging Lidar through the Atmosphere  

PubMed Central

The spatial resolution of a conventional imaging lidar system is constrained by the diffraction limit of the telescope's aperture. The combination of the lidar and synthetic aperture (SA) processing techniques may overcome the diffraction limit and pave the way for a higher resolution air borne or space borne remote sensor. Regarding the lidar transmitting frequency modulation continuous-wave (FMCW) signal, the motion during the transmission of a sweep and the reception of the corresponding echo were expected to be one of the major problems. The given modified Omega-K algorithm takes the continuous motion into account, which can compensate for the Doppler shift induced by the continuous motion efficiently and azimuth ambiguity for the low pulse recurrence frequency limited by the tunable laser. And then, simulation of Phase Screen (PS) distorted by atmospheric turbulence following the von Karman spectrum by using Fourier Transform is implemented in order to simulate turbulence. Finally, the computer simulation shows the validity of the modified algorithm and if in the turbulence the synthetic aperture length does not exceed the similar coherence length of the atmosphere for SAIL, we can ignore the effect of the turbulence.

Guo, Liang; Xing, Mendao; Tang, Yu; Dan, Jing

2008-01-01

62

Advanced Control Algorithms for Compensating the Phase Distortion Due to Transport Delay in Human-Machine Systems  

NASA Technical Reports Server (NTRS)

The desire to create more complex visual scenes in modern flight simulators outpaces recent increases in processor speed. As a result, simulation transport delay remains a problem. New approaches for compensating the transport delay in a flight simulator have been developed and are presented in this report. The lead/lag filter, the McFarland compensator and the Sobiski/Cardullo state space filter are three prominent compensators. The lead/lag filter provides some phase lead, while introducing significant gain distortion in the same frequency interval. The McFarland predictor can compensate for much longer delay and cause smaller gain error in low frequencies than the lead/lag filter, but the gain distortion beyond the design frequency interval is still significant, and it also causes large spikes in prediction. Though, theoretically, the Sobiski/Cardullo predictor, a state space filter, can compensate the longest delay with the least gain distortion among the three, it has remained in laboratory use due to several limitations. The first novel compensator is an adaptive predictor that makes use of the Kalman filter algorithm in a unique manner. In this manner the predictor can accurately provide the desired amount of prediction, while significantly reducing the large spikes caused by the McFarland predictor. Among several simplified online adaptive predictors, this report illustrates mathematically why the stochastic approximation algorithm achieves the best compensation results. A second novel approach employed a reference aircraft dynamics model to implement a state space predictor on a flight simulator. The practical implementation formed the filter state vector from the operator s control input and the aircraft states. The relationship between the reference model and the compensator performance was investigated in great detail, and the best performing reference model was selected for implementation in the final tests. Theoretical analyses of data from offline simulations with time delay compensation show that both novel predictors effectively suppress the large spikes caused by the McFarland compensator. The phase errors of the three predictors are not significant. The adaptive predictor yields greater gain errors than the McFarland predictor for short delays (96 and 138 ms), but shows smaller errors for long delays (186 and 282 ms). The advantage of the adaptive predictor becomes more obvious for a longer time delay. Conversely, the state space predictor results in substantially smaller gain error than the other two predictors for all four delay cases.

Guo, Liwen; Cardullo, Frank M.; Kelly, Lon C.

2007-01-01

63

Multi-Angle Implementation of Atmospheric Correction (MAIAC) Algorithm  

NASA Technical Reports Server (NTRS)

Multi-Angle Implementation of Atmospheric Correction (MAIAC) is a new algorithm developed for MODIS. MAIAC uses a time series analysis and processing of groups of pixels to perform simultaneous retrievals of aerosol properties and surface bidirectional reflectance without typical assumptions about the surface. It is a generic algorithm which works over both dark and bright land surfaces, including deserts. MAIAC has an internal Cloud Mask, a dynamic land-water-snow classification and a surface change mask which allows it to flexibly choose processing path over different surfaces. A distinct feature of MAIAC is a high 1 km resolution of aerosol retrievals which is required in different applications including the air quality analysis. The novel features of MAIAC include the high quality cloud mask, discrimination of aerosol type, including biomass burning smoke and dust, and detection of surface change - all required for high quality aerosol retrievals. An overview of the algorithm, results of AERONET validation, and examples of comparison with MODIS Collection 5 aerosol product and Deep Blue algorithm for different parts of the world, will be presented.

Lyapustin, A.; Wang, Y.

2012-01-01

64

A Resistance Compensation Control Algorithm for a Cable-Driven Hand Exoskeleton for Motor Function Rehabilitation  

Microsoft Academic Search

\\u000a The resistance compensation, especially the friction compensation in the Bowden cable transmission is a difficult issue to\\u000a be handled. Aimed to the resistance reduction requirement in the active rehabilitative motion, a resistance compensation control\\u000a method is proposed. Based on the simplified transmission model, the resistance, including the cable friction as well as the\\u000a mechanical moment of inertial, is formulated. To

Shuang Wang; Jiting Li; Ruoyin Zheng

2010-01-01

65

Advanced Transport Delay Compensation Algorithms: Results of Delay Measurement and Piloted Performance Tests  

NASA Technical Reports Server (NTRS)

This report summarizes the results of delay measurement and piloted performance tests that were conducted to assess the effectiveness of the adaptive compensator and the state space compensator for alleviating the phase distortion of transport delay in the visual system in the VMS at the NASA Langley Research Center. Piloted simulation tests were conducted to assess the effectiveness of two novel compensators in comparison to the McFarland predictor and the baseline system with no compensation. Thirteen pilots with heterogeneous flight experience executed straight-in and offset approaches, at various delay configurations, on a flight simulator where different predictors were applied to compensate for transport delay. The glideslope and touchdown errors, power spectral density of the pilot control inputs, NASA Task Load Index, and Cooper-Harper rating of the handling qualities were employed for the analyses. The overall analyses show that the adaptive predictor results in slightly poorer compensation for short added delay (up to 48 ms) and better compensation for long added delay (up to 192 ms) than the McFarland compensator. The analyses also show that the state space predictor is fairly superior for short delay and significantly superior for long delay than the McFarland compensator.

Guo, Liwen; Cardullo, Frank M.; Kelly, Lon C.

2007-01-01

66

Atmospheric motion vector retrieval using improved tracer selection algorithm  

NASA Astrophysics Data System (ADS)

Tracer selection is the fundamental step in the retrieval of atmospheric motion vectors (AMVs). In this study, a new technique for tracer selection based on extracting the corner points in an infrared (IR) image of a geostationary satellite for the retrieval of AMVs is developed. Corner points are frequently used in computer vision to identify the important features of an image. These points are usually characterized by high gradient values of the image intensity in all directions and lie at the junctions of different brightness regions in the image. Corner points find application in computer vision for motion tracking, stereo vision, mosaics, etc., but this is the first time that the information from corners is used for tracer selection in AMV retrieval. In the present study, a commonly used Harris corner (HC) detection algorithm is followed to extract corners from the image intensity of an IR image. The tracers selected using the HC method are then passed on to the other steps of the retrieval algorithm, viz., tracking, height assignment, and quality control procedures for the retrieval of AMVs. For the initial development of the HC, Meteosat-7 IR images are used to derive AMVs for July and December 2010. The AMVs retrieved using HC are validated against collocated radiosonde observations, and the results are compared with the local anomaly (LA) method as reference. LA is used for tracer selection in operational AMV retrieval algorithm from the Indian geostationary satellite Kalpana-1. AMVs retrieved using HC have shown considerable improvement in the AMV accuracy over the AMVs derived using LA.

Kaur, Inderpreet; Deb, S. K.; Kishtawal, C. M.; Pal, P. K.; Kumar, Raj

2014-02-01

67

A Novel Systematic Error Compensation Algorithm Based on Least Squares Support Vector Regression for Star Sensor Image Centroid Estimation  

PubMed Central

The star centroid estimation is the most important operation, which directly affects the precision of attitude determination for star sensors. This paper presents a theoretical study of the systematic error introduced by the star centroid estimation algorithm. The systematic error is analyzed through a frequency domain approach and numerical simulations. It is shown that the systematic error consists of the approximation error and truncation error which resulted from the discretization approximation and sampling window limitations, respectively. A criterion for choosing the size of the sampling window to reduce the truncation error is given in this paper. The systematic error can be evaluated as a function of the actual star centroid positions under different Gaussian widths of star intensity distribution. In order to eliminate the systematic error, a novel compensation algorithm based on the least squares support vector regression (LSSVR) with Radial Basis Function (RBF) kernel is proposed. Simulation results show that when the compensation algorithm is applied to the 5-pixel star sampling window, the accuracy of star centroid estimation is improved from 0.06 to 6 10?5 pixels. PMID:22164021

Yang, Jun; Liang, Bin; Zhang, Tao; Song, Jingyan

2011-01-01

68

Atmospheric Correction Algorithm for Hyperspectral Remote Sensing of Ocean Color from Space  

Microsoft Academic Search

Existing atmospheric correction algorithms for multichannel remote sensing of ocean color from space were designed for retrieving water-leaving radiances in the visible over clear deep ocean areas and cannot easily be modified for retrievals over turbid coastal waters. We have developed an atmospheric correc- tion algorithm for hyperspectral remote sensing of ocean color with the near-future Coastal Ocean Imaging Spectrometer.

Bo-Cai Gao; Marcos J. Montes; Ziauddin Ahmad; Curtiss O. Davis

2000-01-01

69

Atmospheric Correction Algorithm for Hyperspectral Remote Sensing of Ocean Color from Space  

Microsoft Academic Search

Existing atmospheric correction algorithms for multichannel remote sensing of ocean color from space were designed for retrieving water-leaving radiances in the visible over clear deep ocean areas and cannot easily be modified for retrievals over turbid coastal waters. We have developed an atmospheric correction algorithm for hyperspectral remote sensing of ocean color with the near-future Coastal Ocean Imaging Spectrometer. The

Bo-Cai Gao; Marcos J. Montes; Ziauddin Ahmad; Curtiss O. Davis

2000-01-01

70

A Fast Inverse Motion Compensation Algorithm for DCT-Domain Video Transcoder  

Microsoft Academic Search

The existing methods to perform motion compensation (MC) in discrete cosine transform (DCT) treat each 8 times 8 block as a fundamental unit and, therefore, involve the high cost of reconstructing prediction frames, especially when the half-pixel motion vectors (MVs) are involved. The proposed method operates on a block of variable size 16 Ny times 16 Nx, where Nx and

Vasant Patil; Rajeev Kumar

2008-01-01

71

Design of jitter compensation algorithm for robot vision based on optical flow and Kalman filter.  

PubMed

Image jitters occur in the video of the autonomous robot moving on bricks road, which will reduce robot operation precision based on vision. In order to compensate the image jitters, the affine transformation kinematics were established for obtaining the six image motion parameters. The feature point pair detecting method was designed based on Eigen-value of the feature windows gradient matrix, and the motion parameters equation was solved using the least square method and the matching point pairs got based on the optical flow. The condition number of coefficient matrix was proposed to quantificationally analyse the effect of matching errors on parameters solving errors. Kalman filter was adopted to smooth image motion parameters. Computing cases show that more point pairs are beneficial for getting more precise motion parameters. The integrated jitters compensation software was developed with feature points detecting in subwindow. And practical experiments were conducted on two mobile robots. Results show that the compensation costing time is less than frame sample time and Kalman filter is valid for robot vision jitters compensation. PMID:24600320

Wang, B R; Jin, Y L; Shao, D L; Xu, Y

2014-01-01

72

Algorithm for automatic atmospheric corrections to visible and near-IR satellite imagery  

Microsoft Academic Search

An algorithm is developed for automatic atmospheric correction of satellite imagery of the Earth's surface. The algorithm is based solely on the satellite image being corrected and on climatology of the area. It is applicable to low resolution (1 km field of view) and high resolution (10-80m field of view) imagery of land areas for the solar spectrum. The algorithm

Yoram J. Kaufman; Claudia Sendra

1988-01-01

73

Space radiation effect on fibre optical gyroscope control circuit and compensation algorithm  

NASA Astrophysics Data System (ADS)

The process of a ?-irradiation experiment of fibre optical gyroscope (FOG) control circuit was described, in which it is demonstrated that the FOG control circuit, except for D/A converter, could endure the dose of 10krad with the protection of cabin material. The distortion and drift in D/A converter due to radiation, which affect the performance of FOG seriously, was indicated based on the elemental analysis. Finally, a compensation network based on adaptive neuro-fuzzy inference system is proposed and its function is verified by simulation.

Zhang, Chun-Xi; Tian, Hai-Ting; Li, Min; Jin, Jing; Song, Ning-Fang

2008-02-01

74

Application of Genetic and Gradient Descent Algorithms to Wavefront Compensation for the Deep-Space Optical Communications Receiver  

NASA Astrophysics Data System (ADS)

Present adaptive optics systems use a wavefront sensor to detect phase errors in the incoming wavefront. Knowledge of these phase errors then is used to correct the incoming wavefront, reducing image distortion. However, these systems require that a portion of the incoming light be diverted to the wavefront sensor and away from the main receiver's focal plane, which results in a loss of signal power in the receiver in optical communication applications. Accordingly, it is desirable to develop a system that relies entirely on the focal-plane intensity distribution as opposed to a separate wavefront sensor in order to detect and correct wavefront errors. Two common stochastic optimization techniques -- genetic algorithms and gradient descent algorithms -- are evaluated in this article. Although these algorithms are promising, further work is necessary to enable them to be used in practical adaptive optics systems due to their slow convergence speeds relative to the rate of change in the atmosphere.

Mukai, R.; Wilson, K.; Vilnrotter, V.

2005-05-01

75

Efficient algorithm for locating and sizing series compensation devices in large power transmission grids: II. Solutions and applications  

NASA Astrophysics Data System (ADS)

In a companion manuscript (Frolov et al 2014 New J. Phys. 16 art. no.) , we developed a novel optimization method for the placement, sizing, and operation of flexible alternating current transmission system (FACTS) devices to relieve transmission network congestion. Specifically, we addressed FACTS that provide series compensation (SC) via modification of line inductance. In this sequel manuscript, this heuristic algorithm and its solutions are explored on a number of test cases: a 30-bus test network and a realistically-sized model of the Polish grid (?2700 nodes and ?3300 lines). The results from the 30-bus network are used to study the general properties of the solutions, including nonlocality and sparsity. The Polish grid is used to demonstrate the computational efficiency of the heuristics that leverage sequential linearization of power flow constraints, and cutting plane methods that take advantage of the sparse nature of the SC placement solutions. Using these approaches, we can use the algorithm to solve a Polish transmission grid in tens of seconds. We explore the utility of the algorithm by analyzing transmission networks congested by (i) uniform load growth, (ii) multiple overloaded configurations, and (iii) sequential generator retirements.

Frolov, Vladimir; Backhaus, Scott; Chertkov, Misha

2014-10-01

76

Real-time atmospheric imaging and processing with hybrid adaptive optics and hardware accelerated lucky-region fusion (LRF) algorithm  

NASA Astrophysics Data System (ADS)

Atmospheric turbulences can significantly deteriorate the performance of long-range conventional imaging systems and create difficulties for target identification and recognition. Our in-house developed adaptive optics (AO) system, which contains high-performance deformable mirrors (DMs) and the fast stochastic parallel gradient decent (SPGD) control mechanism, allows effective compensation of such turbulence-induced wavefront aberrations and result in significant improvement on the image quality. In addition, we developed advanced digital synthetic imaging and processing technique, "lucky-region" fusion (LRF), to mitigate the image degradation over large field-of-view (FOV). The LRF algorithm extracts sharp regions from each image obtained from a series of short exposure frames and fuses them into a final improved image. We further implemented such algorithm into a VIRTEX-7 field programmable gate array (FPGA) and achieved real-time video processing. Experiments were performed by combining both AO and hardware implemented LRF processing technique over a near-horizontal 2.3km atmospheric propagation path. Our approach can also generate a universal real-time imaging and processing system with a general camera link input, a user controller interface, and a DVI video output.

Liu, Jony Jiang; Carhart, Gary W.; Beresnev, Leonid A.; Aubailly, Mathieu; Jackson, Christopher R.; Ejzak, Garrett; Kiamilev, Fouad E.

2014-09-01

77

Algorithm of compensating loss of round color mark based on circle fitting  

Microsoft Academic Search

The color mark recognition is a key step in Mirosot, the recognizing results affect the orientation angle to a great extent. During the capturing process there are some loss of color mark because of the environmental disturbing light, which can lead to a big error by calculation. For the above phenomenon, a new algorithm is designed based on the LSM

Jun Zhou; Kui Li; Ting-qi Wang

2005-01-01

78

Design of static synchronous series compensator based damping controller employing invasive weed optimization algorithm.  

PubMed

This paper proposes designing of Static Synchronous Series Compensator (SSSC) based damping controller to enhance the stability of a Single Machine Infinite Bus (SMIB) system by means of Invasive Weed Optimization (IWO) technique. Conventional PI controller is used as the SSSC damping controller which takes rotor speed deviation as the input. The damping controller parameters are tuned based on time integral of absolute error based cost function using IWO. Performance of IWO based controller is compared to that of Particle Swarm Optimization (PSO) based controller. Time domain based simulation results are presented and performance of the controllers under different loading conditions and fault scenarios is studied in order to illustrate the effectiveness of the IWO based design approach. PMID:25140288

Ahmed, Ashik; Al-Amin, Rasheduzzaman; Amin, Ruhul

2014-01-01

79

An accurate approximate algorithm for motion compensation in two-dimensional tomography  

NASA Astrophysics Data System (ADS)

In this paper, we propose two approximate inversion formulae for motion compensation in tomography: for parallel beam and fan beam geometries. Let {\\mathcal E} denote the operator, which corresponds to the error term of an inversion formula. It is proven that in both cases {\\mathcal E}: H_0^m\\rightarrow H_0^{m+1} is bounded; thus, the error term is one order smoother than the original function f in the scale of Sobolev spaces. It is also proven that in both cases if the motion map approaches the identity map, then the norm of {\\mathcal E} approaches zero. The formulae can be easily implemented numerically. Results of numerical experiments in the fan-beam case (which is more common in applications) demonstrate good image quality even when motion is relatively strong. This work was supported in part by NSF grant DMS-0806304, Toshiba Medical Research Institute, USA and Hubert Curien Laboratory, Jean Monnet University, Saint-Etienne, France.

Katsevich, A.

2010-06-01

80

Efficient algorithm for locating and sizing series compensation devices in large power transmission grids: I. Model implementation  

NASA Astrophysics Data System (ADS)

We explore optimization methods for planning the placement, sizing and operations of flexible alternating current transmission system (FACTS) devices installed to relieve transmission grid congestion. We limit our selection of FACTS devices to series compensation (SC) devices that can be represented by modification of the inductance of transmission lines. Our master optimization problem minimizes the l1 norm of the inductance modification subject to the usual line thermal-limit constraints. We develop heuristics that reduce this non-convex optimization to a succession of linear programs (LP) that are accelerated further using cutting plane methods. The algorithm solves an instance of the MatPower Polish Grid model (3299 lines and 2746 nodes) in 40 seconds per iteration on a standard laptopa speed that allows the sizing and placement of a family of SC devices to correct a large set of anticipated congestions. We observe that our algorithm finds feasible solutions that are always sparse, i.e., SC devices are placed on only a few lines. In a companion manuscript, we demonstrate our approach on realistically sized networks that suffer congestion from a range of causes, including generator retirement. In this manuscript, we focus on the development of our approach, investigate its structure on a small test system subject to congestion from uniform load growth, and demonstrate computational efficiency on a realistically sized network.

Frolov, Vladimir; Backhaus, Scott; Chertkov, Misha

2014-10-01

81

An Atmospheric Guidance Algorithm Testbed for the Mars Surveyor Program 2001 Orbiter and Lander  

NASA Technical Reports Server (NTRS)

An Atmospheric Flight Team was formed by the Mars Surveyor Program '01 mission office to develop aerocapture and precision landing testbed simulations and candidate guidance algorithms. Three- and six-degree-of-freedom Mars atmospheric flight simulations have been developed for testing, evaluation, and analysis of candidate guidance algorithms for the Mars Surveyor Program 2001 Orbiter and Lander. These simulations are built around the Program to Optimize Simulated Trajectories. Subroutines were supplied by Atmospheric Flight Team members for modeling the Mars atmosphere, spacecraft control system, aeroshell aerodynamic characteristics, and other Mars 2001 mission specific models. This paper describes these models and their perturbations applied during Monte Carlo analyses to develop, test, and characterize candidate guidance algorithms.

Striepe, Scott A.; Queen, Eric M.; Powell, Richard W.; Braun, Robert D.; Cheatwood, F. McNeil; Aguirre, John T.; Sachi, Laura A.; Lyons, Daniel T.

1998-01-01

82

Compensation for differential atmospheric refraction in the W.M. Keck Observatory adaptive optics system  

Microsoft Academic Search

Differential Atmospheric Refraction (DAR) reduces image quality on ground-based 10-m telescopes equipped with Adaptive Optics (AO). Particularly affected are the long exposure data taken in narrow-band imaging or spectroscopic mode. The magnitude of the DAR is a function of the effective wavelength of the wavefront sensor detector, meteorological variables, the observing wavelength and the elevation of the observation. In this

Paul J. Stomski Jr.; David Le Mignant; Peter L. Wizinowich; Randy D. Campbell; Robert Goodrich

2003-01-01

83

Development of an operational algorithm for removing atmospheric effects from HYDICE and HSI data  

NASA Astrophysics Data System (ADS)

Spectral imaging data have been acquired with the Navy HYDICE (the hyperspectral digital imagery collection experiment) instrument from an aircraft. Similar data will soon be collected with the NASA HSI instrument from the Lewis spacecraft. The majority of users of imaging spectrometer data are interested in studying surface properties. Therefore, atmospheric absorption and scattering effects must be removed from imaging spectrometer data, so that surface reflectance spectra can be derived. Previously, an operational atmosphere removal algorithm, which used the 5S code for modeling the atmospheric scattering effects and the Malkmus narrow band model for modeling atmospheric gaseous transmittances, was specifically designed for deriving surface reflectances from spectral imaging data collected by the NASA JPL airborne visible/infrared imaging spectrometer (AVIRIS). We have recently updated this algorithm by replacing the 5S code, which requires that the sensor be at the top of the atmosphere, with the 6S code, which accommodates sensors at any altitudes. The updated algorithm allows processing of imaging spectrometer data acquired from low- and high-altitude aircraft platforms, and from satellite platforms. We are currently developing another algorithm that uses a line-by line code to calculate atmospheric gaseous transmittances for processing imaging spectrometer data with spectral resolution between approximately 0.5 and 10 nm.

Gao, Bo-Cai; Davis, Curtiss O.

1996-11-01

84

Free-space laser communications with adaptive optics: Atmospheric compensation experiments  

Microsoft Academic Search

\\u000a Refractive index inhomogeneities of the turbulent air cause wave-front distortions of optical waves propagating through the\\u000a atmosphere, leading to such effects as beam spreading, beam wander, and intensity fluctuations (scintillations). These distortions\\u000a are responsible for severe signal fading in free-space optical communications systems and therefore compromise link reliability.\\u000a Wave-front distortions can be mitigated, in principle, with adaptive optics, i.e., real-time

Thomas Weyrauch; Mikhail A. Vorontsov

2008-01-01

85

A rapid atmospheric transmittance algorithm for microwave sounding channels  

Microsoft Academic Search

A rapid transmittance algorithm for NOAA's Advanced Microwave Sounding Units A and B and possible future instruments has been devised. Window channels, water vapor channels, and oxygen-band channels are considered separately; each uses tabular or polynomial approximations to line-wing or near-line absorption from water vapor or oxygen as appropriate. Absorption by cloud liquid water is also included. For oxygen-band channels

Philip W. Rosenkranz

1995-01-01

86

An automatic atmospheric correction algorithm for visible\\/NIR imagery  

Microsoft Academic Search

The automatic correction of atmospheric effects currently requires visible to short-wave spectral bands (400-2500 nm) to derive high accuracy surface reflectance data. Common techniques employ spectral correlations of dark targets in the short-wave infrared (SWIR, around 2.2 mm), blue (480 nm) and red (660 nm) regions to derive the aerosol optical depth. A large number of current Earth-observing satellite sensors

R. Richter; D. Schlpfer; A. Mller

2006-01-01

87

Atmospheric Correction Algorithm for Hyperspectral Remote Sensing of Ocean Color from Space  

NASA Astrophysics Data System (ADS)

Existing atmospheric correction algorithms for multichannel remote sensing of ocean color from space were designed for retrieving water-leaving radiances in the visible over clear deep ocean areas and cannot easily be modified for retrievals over turbid coastal waters. We have developed an atmospheric correction algorithm for hyperspectral remote sensing of ocean color with the near-future Coastal Ocean Imaging Spectrometer. The algorithm uses lookup tables generated with a vector radiative transfer code. Aerosol parameters are determined by a spectrum-matching technique that uses channels located at wavelengths longer than 0.86 m. The aerosol information is extracted back to the visible based on aerosol models during the retrieval of water-leaving radiances. Quite reasonable water-leaving radiances have been obtained when our algorithm was applied to process hyperspectral imaging data acquired with an airborne imaging spectrometer.

Gao, Bo-Cai; Montes, Marcos J.; Ahmad, Ziauddin; Davis, Curtiss O.

2000-02-01

88

Atmospheric correction algorithm for hyperspectral remote sensing of ocean color from space.  

PubMed

Existing atmospheric correction algorithms for multichannel remote sensing of ocean color from space were designed for retrieving water-leaving radiances in the visible over clear deep ocean areas and cannot easily be modified for retrievals over turbid coastal waters. We have developed an atmospheric correction algorithm for hyperspectral remote sensing of ocean color with the near-future Coastal Ocean Imaging Spectrometer. The algorithm uses look-up tables generated with a vector radiative transfer code. Aerosol parameters are determined by a spectrum-matching technique that uses channels located at wavelengths longer than 0.86 mum. The aerosol information is extracted back to the visible based on aerosol models during the retrieval of water-leaving radiances. Quite reasonable water-leaving radiances have been obtained when our algorithm was applied to process hyperspectral imaging data acquired with an airborne imaging spectrometer. PMID:18337964

Gao, B C; Montes, M J; Ahmad, Z; Davis, C O

2000-02-20

89

The Results of a Simulator Study to Determine the Effects on Pilot Performance of Two Different Motion Cueing Algorithms and Various Delays, Compensated and Uncompensated  

NASA Technical Reports Server (NTRS)

A study was conducted employing the Visual Motion Simulator (VMS) at the NASA Langley Research Center, Hampton, Virginia. This study compared two motion cueing algorithms, the NASA adaptive algorithm and a new optimal control based algorithm. Also, the study included the effects of transport delays and the compensation thereof. The delay compensation algorithm employed is one developed by Richard McFarland at NASA Ames Research Center. This paper reports on the analyses of the results of analyzing the experimental data collected from preliminary simulation tests. This series of tests was conducted to evaluate the protocols and the methodology of data analysis in preparation for more comprehensive tests which will be conducted during the spring of 2003. Therefore only three pilots were used. Nevertheless some useful results were obtained. The experimental conditions involved three maneuvers; a straight-in approach with a rotating wind vector, an offset approach with turbulence and gust, and a takeoff with and without an engine failure shortly after liftoff. For each of the maneuvers the two motion conditions were combined with four delay conditions (0, 50, 100 & 200ms), with and without compensation.

Guo, Li-Wen; Cardullo, Frank M.; Telban, Robert J.; Houck, Jacob A.; Kelly, Lon C.

2003-01-01

90

Atmospheric correction algorithm based on vector radiative transfer modeling for hyperspectral remote sensing of ocean color  

Microsoft Academic Search

Multi-channel remote sensing of ocean color from space has a rich history -- from the past CZCS, to the present SeaWiFS, and to the near-future MODIS. The atmospheric correction algorithms for processing remotely sensed data from these sensors were mainly developed by Howard Gordon at University of Miami. The algorithms were primarily designed for retrieving water leaving radiances in the

BoCai Gao; Marcos J. Montes; Ziauddin Ahmad; Curtiss O. Davis

1999-01-01

91

Parallel algorithms for semi-Lagrangian transport in global atmospheric circulation models  

SciTech Connect

Global atmospheric circulation models (GCM) typically have three primary algorithmic components: columnar physics, spectral transform, and semi-Lagrangian transport. In developing parallel implementations, these three components are equally important and can be examined somewhat independently. A two-dimensional horizontal data decomposition of the three-dimensional computational grid leaves all physics computations on processor, and the only efficiency issues arise in load balancing. A recently completed study by the authors of different approaches to parallelizing the spectral transform showed several viable algorithms. Preliminary results of an analogous study of algorithmic alternatives for parallel semi-Lagrangian transport are described here.

Drake, J.B.; Worley, P.H. [Oak Ridge National Lab., TN (United States); Michalakes, J.; Foster, I.T. [Argonne National Lab., IL (United States)

1995-02-01

92

Atmospheric correction algorithm based on vector radiative transfer modeling for hyperspectral remote sensing of ocean color  

NASA Astrophysics Data System (ADS)

Multi-channel remote sensing of ocean color from space has a rich history -- from the past CZCS, to the present SeaWiFS, and to the near-future MODIS. The atmospheric correction algorithms for processing remotely sensed data from these sensors were mainly developed by Howard Gordon at University of Miami. The algorithms were primarily designed for retrieving water leaving radiances in the visible spectral region over clear deep ocean areas. The information about atmospheric aerosols is derived from channels between 0.66 and 0.87 micrometer, where the water leaving radiances are close to zero. The derived aerosol information is extrapolated back to the visible when retrieving water leaving radiances from remotely sensed data. For the turbid coastal environment, the water leaving radiances for channels between 0.66 and 0.87 micrometer may not be close to zero because of back scattering by suspended materials in the water. Under these conditions, the channels are no longer useful for deriving information on atmospheric aerosols. As a result, the algorithms developed for applications to clear ocean waters cannot be easily modified to retrieve water leaving radiances from remote sensing data acquired over the costal environments. We have recently developed a fast and fully functional atmospheric correction algorithm for hyperspectral remote sensing of ocean color with the Coastal Ocean Imaging Spectrometer (COIS). Our algorithm uses lookup tables generated with a vector radiative transfer code developed by Ahmad and Fraser (1982) and a spectral matching technique for the retrieval of water leaving radiances. The information on atmospheric aerosols is estimated using dark channels beyond 0.86 micron. Quite reasonable results were obtained when applying the algorithm to process spectral imaging data acquired over Chesapeake Bay with the NASA JPL Airborne Visible Infrared Imaging Spectrometer (AVIRIS).

Gao, BoCai; Montes, Marcos J.; Ahmad, Ziauddin; Davis, Curtiss O.

1999-10-01

93

Validation of a DDV-based aerosol optical depth retrieval algorithm for atmospheric corrections  

Microsoft Academic Search

One of the classical weaknesses of atmospheric correction algorithms of remotely sensed data is their statistically limited validation data sets. Validation procedures are generally carried out over a limited sparse ground based data sets. To overcome this constraint, the authors developed an approach using the multi-altitude regression more appropriate to the validation needs of high altitude or satellite sensors. The

F. Zagolski; Minh-Nghia Nguyen

1999-01-01

94

An atmospheric correction algorithm for hyperspectral imagery of lake water by Chinese satellite HJ-1A  

Microsoft Academic Search

This paper demonstrates the Ruddick's algorithm to utilize atmospheric correction with the hyper-spectral imagery over Chinese turbid lake water obtained by China first hyperspectral imager (HSI) onboard HJ-1A. The paper studies on the sensor characteristics and analyzes the optical properties of turbid lake water in Taihu Lake. Based on consideration about real circumstances, the paper recalibrates parameter? of value taken

Hua Xua; Xingfa Gu; Qiu Yin; Li Li; Zhenghua Chen; Yuhuan Ren; Weizhen Hou; Jia Liu; Pengfei Yin

2010-01-01

95

A multi-channel atmospheric correction algorithm for remote sensing of coastal waters  

Microsoft Academic Search

In order to make reliable estimates of chlorophyll concentrations and suspended matter in the ocean, accurate retrievals of water leaving reflectances are required. The present operational atmospheric correction algorithms work reasonably well over clear ocean areas but gives incorrect results over brighter coastal waters. This is mainly due to the fact that the turbid waters are not dark for the

Bo-Cai Gao; Marcos J. Montes; Rong-Rong Li

2007-01-01

96

Mars Entry Atmospheric Data System Trajectory Reconstruction Algorithms and Flight Results  

NASA Technical Reports Server (NTRS)

The Mars Entry Atmospheric Data System is a part of the Mars Science Laboratory, Entry, Descent, and Landing Instrumentation project. These sensors are a system of seven pressure transducers linked to ports on the entry vehicle forebody to record the pressure distribution during atmospheric entry. These measured surface pressures are used to generate estimates of atmospheric quantities based on modeled surface pressure distributions. Specifically, angle of attack, angle of sideslip, dynamic pressure, Mach number, and freestream atmospheric properties are reconstructed from the measured pressures. Such data allows for the aerodynamics to become decoupled from the assumed atmospheric properties, allowing for enhanced trajectory reconstruction and performance analysis as well as an aerodynamic reconstruction, which has not been possible in past Mars entry reconstructions. This paper provides details of the data processing algorithms that are utilized for this purpose. The data processing algorithms include two approaches that have commonly been utilized in past planetary entry trajectory reconstruction, and a new approach for this application that makes use of the pressure measurements. The paper describes assessments of data quality and preprocessing, and results of the flight data reduction from atmospheric entry, which occurred on August 5th, 2012.

Karlgaard, Christopher D.; Kutty, Prasad; Schoenenberger, Mark; Shidner, Jeremy; Munk, Michelle

2013-01-01

97

An Atmospheric Correction Algorithm for FY-3/ MERSI Data over the Land: First Results  

NASA Astrophysics Data System (ADS)

Feng-Yun (FY-3) is the second Chinese Polar Orbiting Meteorological Satellite with global, three-dimensional, quantitative, and multispectral capabilities. Medium Resolution Spectral Imager (MERSI) has 20 channels onboard the FY-3A and FY-3B satellite. MERSI has five channels (four VIS and one thermal IR), with a spatial resolution of 250 m. Prior to the derivation of various biophysical parameters based on surface reflectance, the top of the atmosphere signal need to be radiometrically calibrated and corrected for atmospheric effects. This paper presents an atmospheric correction algorithm for FY3/MERSI in the visible to near-infrared band over the land. Previous operational correction schemes have assumed a Lambertian surface. A new atmospheric correction algorithm is developed to take into account the directional properties of the observed surface by a kernel-based Bi-directional Reflectance Distribution Function (BRDF) model. This algorithm is applied to remote sensing data from FY3/MERSI and compared with Moderate Resolution Imaging Spectro radiometer (MODIS) surface reflectance products (MOD09GA). It is found in the study that the relative accuracy of data, obtained with these two devices, was consistent with the acceptable overall accuracy of 73%. Furthermore, spatial resolution of MERSI is superior as compared to that of MODIS. Therefore, FY-3/MERSI can serve a reliable and new data source for quantifying global environmental change.

Guang, Jie; Xue, Yong; Liang, Shunlin; Liu, Qiang; Mei, LinLu; Shi, Yuanli

2014-05-01

98

Development of an Aircraft Approach and Departure Atmospheric Profile Generation Algorithm  

NASA Technical Reports Server (NTRS)

In support of NASA Virtual Airspace Modeling and Simulation (VAMS) project, an effort was initiated to develop and test techniques for extracting meteorological data from landing and departing aircraft, and for building altitude based profiles for key meteorological parameters from these data. The generated atmospheric profiles will be used as inputs to NASA s Aircraft Vortex Spacing System (AVOLSS) Prediction Algorithm (APA) for benefits and trade analysis. A Wake Vortex Advisory System (WakeVAS) is being developed to apply weather and wake prediction and sensing technologies with procedures to reduce current wake separation criteria when safe and appropriate to increase airport operational efficiency. The purpose of this report is to document the initial theory and design of the Aircraft Approach Departure Atmospheric Profile Generation Algorithm.

Buck, Bill K.; Velotas, Steven G.; Rutishauser, David K. (Technical Monitor)

2004-01-01

99

A Portable Ground-Based Atmospheric Monitoring System (PGAMS) for the Calibration and Validation of Atmospheric Correction Algorithms Applied to Aircraft and Satellite Images  

NASA Technical Reports Server (NTRS)

Detecting changes in the Earth's environment using satellite images of ocean and land surfaces must take into account atmospheric effects. As a result, major programs are underway to develop algorithms for image retrieval of atmospheric aerosol properties and atmospheric correction. However, because of the temporal and spatial variability of atmospheric transmittance it is very difficult to model atmospheric effects and implement models in an operational mode. For this reason, simultaneous in situ ground measurements of atmospheric optical properties are vital to the development of accurate atmospheric correction techniques. Presented in this paper is a spectroradiometer system that provides an optimized set of surface measurements for the calibration and validation of atmospheric correction algorithms. The Portable Ground-based Atmospheric Monitoring System (PGAMS) obtains a comprehensive series of in situ irradiance, radiance, and reflectance measurements for the calibration of atmospheric correction algorithms applied to multispectral. and hyperspectral images. The observations include: total downwelling irradiance, diffuse sky irradiance, direct solar irradiance, path radiance in the direction of the north celestial pole, path radiance in the direction of the overflying satellite, almucantar scans of path radiance, full sky radiance maps, and surface reflectance. Each of these parameters are recorded over a wavelength range from 350 to 1050 nm in 512 channels. The system is fast, with the potential to acquire the complete set of observations in only 8 to 10 minutes depending on the selected spatial resolution of the sky path radiance measurements

Schiller, Stephen; Luvall, Jeffrey C.; Rickman, Doug L.; Arnold, James E. (Technical Monitor)

2000-01-01

100

The Computational Complexity and Parallel Scalability of Atmospheric Data Assimilation Algorithms  

Microsoft Academic Search

This paper quantifies the computational complexity and parallel scalability of two algorithms for four-di- mensional data assimilation (4DDA) at NASA's Global Modeling and Assimilation Office (GMAO). The first, the Goddard Earth Observing System Data Assimilation System (GEOS DAS), uses an atmospheric general circulation model (GCM) and an observation-space-based analysis system, the Physical-Space Statistical Analysis System (PSAS). GEOS DAS is very

P. M. L YSTER; J. GUO; T. C LUNE; J. W. LARSON

2004-01-01

101

A Cloudless land atmosphere radiosounding database for generating land surface temperature retrieval algorithms  

Microsoft Academic Search

A database of global, cloud-free, atmospheric radiosounding profiles was compiled with the aim of simulating radiometric measurements from satellite-borne sensors in the thermal infrared. The objective of the simulation is to generate split-window (SW) and dual-angle (DA) algorithms for the retrieval of land surface temperature (LST) from Terra\\/Moderate Resolution Imaging Spectroradiometer (MODIS) and Envisat\\/advanced along track scanning radiometer (AATSR) data.

J. M. Galve; C. Coll; V. Caselles; R. Niclos; E. Valor; J. M. Sanchez; M. Mira

2007-01-01

102

Artificial-neural-network-based atmospheric correction algorithm: application to MERIS data  

NASA Astrophysics Data System (ADS)

After the successful launch of the Medium Resolution Imaging Spectrometer (MERIS) on board of the European Space Agency (ESA) Environmental Satellite (ENVISAT) on March 1st 2002, first MERIS data are available for validation purposes. The primary goal of the MERIS mission is to measure the color of the sea with respect to oceanic biology and marine water quality. We present an atmospheric correction algorithm for case-I waters based on the inverse modeling of radiative transfer calculations by artificial neural networks. The proposed correction scheme accounts for multiple scattering and high concentrations of absorbing aerosols (e.g. desert dust). Above case-I waters, the measured near infrared path radiance at Top-Of-Atmosphere (TOA) is assumed to originate from atmospheric processes only and is used to determine the aerosol properties with the help of an additional classification test in the visible spectral region. A synthetic data set is generated from radiative transfer simulations and is subsequently used to train different Multi-Layer-Perceptrons (MLP). The atmospheric correction scheme consists of two steps. First a set of MLPs is used to derive the aerosol optical thickness (AOT) and the aerosol type for each pixel. Second these quantities are fed into a further MLP trained with simulated data for various chlorophyll concentrations to perform the radiative transfer inversion and to obtain the water-leaving radiance. In this work we apply the inversion algorithm to a MERIS Level 1b data track covering the Indian Ocean along the west coast of Madagascar.

Schroeder, Thomas; Fischer, Juergen; Schaale, Michael; Fell, Frank

2003-05-01

103

The Algorithm Theoretical Basis Document for the GLAS Atmospheric Data Products  

NASA Technical Reports Server (NTRS)

The purpose of this document is to present a detailed description of the algorithm theoretical basis for each of the GLAS data products. This will be the final version of this document. The algorithms were initially designed and written based on the authors prior experience with high altitude lidar data on systems such as the Cloud and Aerosol Lidar System (CALS) and the Cloud Physics Lidar (CPL), both of which fly on the NASA ER-2 high altitude aircraft. These lidar systems have been employed in many field experiments around the world and algorithms have been developed to analyze these data for a number of atmospheric parameters. CALS data have been analyzed for cloud top height, thin cloud optical depth, cirrus cloud emittance (Spinhirne and Hart, 1990) and boundary layer depth (Palm and Spinhirne, 1987, 1998). The successor to CALS, the CPL, has also been extensively deployed in field missions since 2000 including the validation of GLAS and CALIPSO. The CALS and early CPL data sets also served as the basis for the construction of simulated GLAS data sets which were then used to develop and test the GLAS analysis algorithms.

Palm, Stephen P.; Hart, William D.; Hlavka, Dennis L.; Welton, Ellsworth J.; Spinhirne, James D.

2012-01-01

104

Study on image motion compensation technology for Chinese geostationary meterological satellite remote sensing  

NASA Astrophysics Data System (ADS)

The new generation Chinese Geostationary Meteorological Satellite (CGMS) adopts three-axis stabilized attitude control mode, using many payloads, such as spaceborne imaging radiometer and atmospheric vertical sounder, etc, implements all weather and real-time observation to the atmospheric environment of the Earth. The deviation of the orbit results in the optical axis of the payloads to deviate its normal direction and then the image quality becomes lower. To acquire high quality image, an algorithm of image motion compensation (IMC) is designed. Simulation results demonstrate that the proposed algorithm can effectively compensate the deviation of the optical axis from the motion of the satellite orbit.

Chen, Yinchao; Wang, Zhigang

2007-11-01

105

Simulation of atmospheric turbulence for a qualitative evaluation of image restoration algorithms with motion detection  

NASA Astrophysics Data System (ADS)

Remote sensing applications are generally concerned with observing objects over long distances. When imaging over long horizontal paths, image resolution is limited by the atmosphere rather than by the design and quality of the optical system being used. Atmospheric turbulence can cause quite severe image degradation, the foremost effects being blurring and image motion. Recently, interest in image processing solutions has been rising, not least of all because of the comparatively low cost of computational power, and also due to an increasing number of imaging applications that require the correction of extended objects rather than point-like sources only. At present, the majority of these image processing methods aim exclusively at the restoration of static scenes. But there is a growing interest in enhancing turbulence mitigation methods to include moving objects as well. However, an unbiased qualitative evaluation of the respective restoration results proves difficult if little or no additional information on the "true image" is available. Therefore, in this paper synthetic ground truth data containing moving vehicles were generated and a first-order atmospheric propagation simulation was implemented in order to test such algorithms. The simulation employs only one phase screen and assumes isoplanatic conditions (only global image motion) while scintillation effects are ignored.

Huebner, Claudia S.; Gladysz, Szymon

2012-10-01

106

Adaptive cascade control of a hydraulic actuator with an adaptive dead-zone compensation and optimization based on evolutionary algorithms  

Microsoft Academic Search

This work presents an adaptive cascade controller tuned by using evolutionary algorithms for the trajectory tracking control of a hydraulic actuator with an overlapped proportional valve. The hydraulic actuator mathematical model includes the dead-zone nonlinearity due to the use of the overlapped valve. By considering the hydraulic actuator as a mechanical subsystem driven by a hydraulic one, a cascade strategy

Leandro dos Santos Coelho; Mauro Andr Barbosa Cunha

2011-01-01

107

An atmospheric correction algorithm for remote identification of non-Lambertian surfaces and its range of validity  

SciTech Connect

The usefulness of remotely sensed surface data depends on the ability to correct for atmospheric pertubations on the image. An atmospheric correction algorithm has been proposed which removes atmospheric pertubations from off-nadir measured radiances at the top of the atmosphere in the visible and near-infrared wavelength region. The ability of the model to reproduce radiance distributions at the surface from radiances at the top of the atmosphere is tested and found to be better than 15%. The correction formalism requires as minimum information the total optical depth of the atmosphere and the surface albedo. In this study the accuracy of the model to assumptions about the aerosol phase function, the single-scattering albedo and the vertical profile of the optical depth is also tested.

Gratzki, A.; Gerstl, S.A.W.

1987-02-20

108

Phase compensation of SAL imaging combining Rayleigh LGS with PGA in strong turbulence  

NASA Astrophysics Data System (ADS)

High imaging resolution can be achieved by using synthetic aperture ladar (SAL) with laser radiation source. The destruction of the signal phase information caused by atmospheric turbulence makes the optical heterodyne detection efficiency reduce. Therefore the imaging performance of SAL degraded seriously. The study on the influence of atmospheric turbulence on SAL imaging is of great significance and an effective compensation method of image is necessary to be found. Research shows that conventional phase gradient autofocus (PGA) algorithm has some improvement on SAL imaging only in weak turbulence. The mixed phase compensation method combining Rayleigh laser guide star (LGS) with PGA algorithm is presented based on the real-time detection of optical wavefront phase distortion with Rayleigh LGS and the phase compensation method of the SAL images. The phase distortion caused by different turbulence intensities with von Karman spectrum is estimated with Rayleigh LGS. SAL echo signals are compensated with the estimated phase and the PGA algorithm is implemented in the final imaging data. The results show that significant improvements of the SAL images in moderate turbulence are obtained and the images can be identified basically by using the mixed phase compensation method in strong turbulence. The focusing effect of the SAL images is improved effectively, and a higher SAL resolution is gained in azimuth. In addition, the research of SAL imaging compensation in atmospheric turbulence in a slant path is carried out for the first time, which is of great significance to the practical application of SAL.

Han, Yan-yan; Lu, Fang; Han, Xiang'e.; Liu, Chun-bo

2013-09-01

109

Two-dimensional atmospheric transport and chemistry model - Numerical experiments with a new advection algorithm  

NASA Technical Reports Server (NTRS)

Extensive testing of the advective scheme proposed by Prather (1986) has been carried out in support of the California Institute of Technology-Jet Propulsion Laboratory two-dimensional model of the middle atmosphere. The original scheme is generalized to include higher-order moments. In addition, it is shown how well the scheme works in the presence of chemistry as well as eddy diffusion. Six types of numerical experiments including simple clock motion and pure advection in two dimensions have been investigated in detail. By comparison with analytic solutions, it is shown that the new algorithm can faithfully preserve concentration profiles, has essentially no numerical diffusion, and is superior to a typical fourth-order finite difference scheme.

Shia, Run-Lie; Ha, Yuk Lung; Wen, Jun-Shan; Yung, Yuk L.

1990-01-01

110

Ground based measurements on reflectance towards validating atmospheric correction algorithms on IRS-P6 AWiFS data  

NASA Astrophysics Data System (ADS)

In Earth observation, the atmosphere has a non-negligible influence on the visible and infrared radiation which is strong enough to modify the reflected electromagnetic signal and at-target reflectance. Scattering of solar irradiance by atmospheric molecules and aerosol generates path radiance, which increases the apparent surface reflectance over dark surfaces while absorption by aerosols and other molecules in the atmosphere causes loss of brightness to the scene, as recorded by the satellite sensor. In order to derive precise surface reflectance from satellite image data, it is indispensable to apply the atmospheric correction which serves to remove the effects of molecular and aerosol scattering. In the present study, we have implemented a fast atmospheric correction algorithm to IRS-P6 AWiFS satellite data which can effectively retrieve surface reflectance under different atmospheric and surface conditions. The algorithm is based on MODIS climatology products and simplified use of Second Simulation of Satellite Signal in Solar Spectrum (6S) radiative transfer code, which is used to generate look-up-tables (LUTs). The algorithm requires information on aerosol optical depth for correcting the satellite dataset. The proposed method is simple and easy to implement for estimating surface reflectance from the at sensor recorded signal, on a per pixel basis. The atmospheric correction algorithm has been tested for different IRS-P6 AWiFS False color composites (FCC) covering the ICRISAT Farm, Patancheru, Hyderabad, India under varying atmospheric conditions. Ground measurements of surface reflectance representing different land use/land cover, i.e., Red soil, Chick Pea crop, Groundnut crop and Pigeon Pea crop were conducted to validate the algorithm and found a very good match between surface reflectance and atmospherically corrected reflectance for all spectral bands. Further, we aggregated all datasets together and compared the retrieved AWiFS reflectance with aggregated ground measurements which showed a very good correlation of 0.96 in all four spectral bands (i.e. green, red, NIR and SWIR). In order to quantify the accuracy of the proposed method in the estimation of the surface reflectance, the root mean square error (RMSE) associated to the proposed method was evaluated. The analysis of the ground measured versus retrieved AWiFS reflectance yielded smaller RMSE values in case of all four spectral bands. EOS TERRA/AQUA MODIS derived AOD exhibited very good correlation of 0.92 and the data sets provides an effective means for carrying out atmospheric corrections in an operational way. Keywords: Atmospheric correction, 6S code, MODIS, Spectroradiometer, Sun-Photometer

Rani Sharma, Anu; Kharol, Shailesh Kumar; Kvs, Badarinath; Roy, P. S.

111

Physics Based Target Detection Using a Hybrid Algorithm With an Infeasibility Metric  

Microsoft Academic Search

This paper develops (and applies) a hybrid target detector that incorporates structured backgrounds and physics based modeling together with a geometric infeasibility metric. More often than not, detection algorithms are usually applied to atmospherically compensated hyperspectral imagery. Rather than compensate the imagery, we take the opposite approach by using a physics based model to generate permutations of what the target

Emmett J. Ientilucci; John R. Schott

2006-01-01

112

Compensation for the Atmosphere in Radiance Measured by the Airborne Visible/Infrared Imaging Spectrometer and Applications to an Advanced Land Remote Sensing System  

NASA Technical Reports Server (NTRS)

The Airborne Visible/Infrared Imaging Spectrometer measures spatial images of the total upwelling spectral radiance from 400 to 2500 nm through 10 nm spectral channels. Quantitative research and application objectives for surface investigations require conversion of the measured radiance to surface reflectance or surface leaving radiance. To calculate apparent surface reflectance an estimation of atmospheric water vapor abundance, cirrus cloud effects, surface pressure elevation and aerosol optical depth is also required. Algorithms for the estimation of these parameters from the AVIRIS data themselves are described. Based upon these determined atmospheric parameters we show an example of the calculation of apparent surface reflectance from the AVIRIS-measured radiance using a radiative transfer code.

Green, R. O.; Conel, J. E.

1993-01-01

113

Assessment of Polarization Effect on Efficiency of Levenberg-Marquardt Algorithm in Case of Thin Atmosphere Over Black Surface  

NASA Technical Reports Server (NTRS)

The Levenberg-Marquardt algorithm [1, 2] provides a numerical iterative solution to the problem of minimization of a function over a space of its parameters. In our work, the Levenberg-Marquardt algorithm retrieves optical parameters of a thin (single scattering) plane parallel atmosphere irradiated by collimated infinitely wide monochromatic beam of light. Black ground surface is assumed. Computational accuracy, sensitivity to the initial guess and the presence of noise in the signal, and other properties of the algorithm are investigated in scalar (using intensity only) and vector (including polarization) modes. We consider an atmosphere that contains a mixture of coarse and fine fractions. Following [3], the fractions are simulated using Henyey-Greenstein model. Though not realistic, this assumption is very convenient for tests [4, p.354]. In our case it yields analytical evaluation of Jacobian matrix. Assuming the MISR geometry of observation [5] as an example, the average scattering cosines and the ratio of coarse and fine fractions, the atmosphere optical depth, and the single scattering albedo, are the five parameters to be determined numerically. In our implementation of the algorithm, the system of five linear equations is solved using the fast Cramer s rule [6]. A simple subroutine developed by the authors, makes the algorithm independent from external libraries. All Fortran 90/95 codes discussed in the presentation will be available immediately after the meeting from sergey.v.korkin@nasa.gov by request.

Korkin, S.; Lyapustin, A.

2012-01-01

114

An Adaptive Numeric Predictor-corrector Guidance Algorithm for Atmospheric Entry Vehicles. M.S. Thesis - MIT, Cambridge  

NASA Technical Reports Server (NTRS)

An adaptive numeric predictor-corrector guidance is developed for atmospheric entry vehicles which utilize lift to achieve maximum footprint capability. Applicability of the guidance design to vehicles with a wide range of performance capabilities is desired so as to reduce the need for algorithm redesign with each new vehicle. Adaptability is desired to minimize mission-specific analysis and planning. The guidance algorithm motivation and design are presented. Performance is assessed for application of the algorithm to the NASA Entry Research Vehicle (ERV). The dispersions the guidance must be designed to handle are presented. The achievable operational footprint for expected worst-case dispersions is presented. The algorithm performs excellently for the expected dispersions and captures most of the achievable footprint.

Spratlin, Kenneth Milton

1987-01-01

115

Compensation Chemistry  

ERIC Educational Resources Information Center

Congress, the news media, and the Internal Revenue Service (IRS) continue to cast a wary eye on the compensation of nonprofit leaders. Hence, any college or university board that falls short of IRS expectations in its procedures for setting the president's compensation is putting the president, other senior officials, and board members at

Roady, Celia

2008-01-01

116

Atmospheric Motion Vectors Derived via a New Nested Tracking Algorithm Developed for the GOES-R Advanced Baseline Imager (ABI)  

NASA Astrophysics Data System (ADS)

A new Atmospheric Motion Vector (AMV) nested tracking algorithm has been developed for the Advanced Baseline Imager (ABI) to be flown on NOAA's future GOES-R satellite. The algorithm has been designed to capture the dominant motion in each target scene from a family of local motion vectors derived for each target scene. Capturing this dominant motion is achieved through use of a two-dimensional clustering algorithm that segregates local displacements into clusters. The dominant motion is taken to be the average of the local displacements of points belonging to the largest cluster. This approach prevents excessive averaging of motion that may be occurring at multiple levels or at different scales that can lead to a slow speed bias and a poor quality AMV. A representative height is assigned to the dominant motion vector through exclusive use of cloud heights from pixels belonging to the largest cluster. This algorithm has been demonstrated to significantly improve the slow speed bias typically observed in AMVs derived from satellite imagery. Meteosat SEVERI imagery is serving as an important GOES-R ABI proxy data source for the development, testing, and validation of the GOES-R AMV algorithms given its similarities (spectral coverage, pixel resolution, and scanning rate) and performance (spectral noise, navigation/registration) to the future GOES-R ABI. The new GOES-R AMV algorithm is also being applied to the instrumentation on the current operational GOES series of satellites and is expected to replace the heritage AMV algorithm being used in NESDIS operations today. Plans at NOAA/NESDIS also include using the new GOES-R AMV algorithm to generate AMVs from the future VIIRS instrument on the NPP satellite. Details of the GOES-R ABI AMV algorithm and the validation results will be presented and discussed.

Daniels, J.; Bresky, W.; Wanzong, S.; Velden, C.

2012-12-01

117

Genetic algorithm applied to a Soil-Vegetation-Atmosphere system: Sensitivity and uncertainty analysis  

NASA Astrophysics Data System (ADS)

Numerical models are of precious help for predicting water fluxes in the vadose zone and more specifically in Soil-Vegetation-Atmosphere (SVA) systems. For such simulations, robust models and representative soil hydraulic parameters are required. Calibration of unsaturated hydraulic properties is known to be a difficult optimization problem due to the high non-linearity of the water flow equations. Therefore, robust methods are needed to avoid the optimization process to lead to non-optimal parameters. Evolutionary algorithms and specifically genetic algorithms (GAs) are very well suited for those complex parameter optimization problems. Additionally, GAs offer the opportunity to assess the confidence in the hydraulic parameter estimations, because of the large number of model realizations. The SVA system in this study concerns a pine stand on a heterogeneous sandy soil (podzol) in the Campine region in the north of Belgium. Throughfall and other meteorological data and water contents at different soil depths have been recorded during one year at a daily time step in two lysimeters. The water table level, which is varying between 95 and 170 cm, has been recorded with intervals of 0.5 hour. The leaf area index was measured as well at some selected time moments during the year in order to evaluate the energy which reaches the soil and to deduce the potential evaporation. Water contents at several depths have been recorded. Based on the profile description, five soil layers have been distinguished in the podzol. Two models have been used for simulating water fluxes: (i) a mechanistic model, the HYDRUS-1D model, which solves the Richards' equation, and (ii) a compartmental model, which treats the soil profile as a bucket into which water flows until its maximum capacity is reached. A global sensitivity analysis (Morris' one-at-a-time sensitivity analysis) was run previously to the calibration, in order to check the sensitivity in the chosen parameter search space. For the inversion procedure a genetical algorithm (GA) was used. Specific features such as elitism, roulette-wheel process for selection operator and island theory were implemented. Optimization was based on the water content measurements recorded at several depths. Ten scenarios have been elaborated and applied on the two lysimeters in order to investigate the impact of the conceptual model in terms of processes description (mechanistic or compartmental) and geometry (number of horizons in the profile description) on the calibration accuracy. Calibration leads to a good agreement with the measured water contents. The most critical parameters for improving the goodness of fit are the number of horizons and the type of process description. Best fit are found for a mechanistic model with 5 horizons resulting in absolute differences between observed and simulated water contents less than 0.02 cm3cm-3 in average. Parameter estimate analysis shows that layers thicknesses are poorly constrained whereas hydraulic parameters are much well defined.

Schneider, Sbastien; Jacques, Diederik; Mallants, Dirk

2010-05-01

118

Improved Clutter Suppression Algorithm for Atmospheric Target Detection Using Polarimetric Doppler Radar  

Microsoft Academic Search

When using dual-orthogonal frequency modulation continuous wave (FMCW) polarimetric radar, the polarimetric range-Doppler spectra of the atmospheric targets are contaminated by noise, clutter, and artificial signals that disturb the analysis of atmospheric target parameters, such as reflectivity, mean Doppler velocity, and Doppler width. This paper describes an improved clutter suppression method that is able to detect most atmospheric targets while

Mi He; Yongjian Nian; Xuesong Wang; Shunping Xiao; Yongzhen Li

2011-01-01

119

An NN-based atmospheric correction algorithm for Landsat\\/TM thermal infrared data  

Microsoft Academic Search

Land surface temperature (LST) is a key variable for studies of global or regional land surface processes, energy and water cycle, and thus, has important applications in various areas. Atmospheric correction is a major issue in LST retrieval using remote sensing data because the presence of the atmosphere always influences the radiation from the ground to the space sensor. Atmospheric

Liu Hailei; Xu Lisheng; Bianba Ciren; Basang Zhuoga; Ding Jilie; Deng Xiaobo; Du yanxia

2010-01-01

120

Estimating the height of the planetary boundary layer for transport and diffusion atmospheric models: A four algorithm comparison  

SciTech Connect

The authors present the results of a performance evaluation of four algorithms that determine the height of the Planetary Boundary Layer (PBL) against both forecasted and observed PBL heights derived by human analysis (taken to be the forecasted and observed truth). The PBL height determines the direction and speed of pollution movement, as well as the vertical depth over which the effluent will be mixed, and therefore is important for accurate transport and diffusion modeling. Three of these algorithms are methods used by the Short-range Layered Atmospheric Model (SLAM). Although designed to be used with observed upper-air data, these three methods have been adapted to utilize forecast soundings from the Regional Atmospheric Modeling System (RAMS) forecast model. The fourth method relies on the properties of turbulent kinetic energy (TKE) predicted by the RAMS forecast model to determine PBL heights. The results of the study indicate that two of the three SLAM model algorithms, and the RAMS TKE derived PBL heights all produce reasonable results compared to those derived by human analysis. The results suggest an ensemble approach in which the transport and diffusion calculations are performed using each of the three algorithms may produce the best results.

Russ, R.L.; Dean, D.; Walters, M.K.

1999-07-01

121

Assessment of Polarization Effect on Efficiency of Levenberg-Marquardt Algorithm in Case of Thin Atmosphere over Black Surface  

NASA Astrophysics Data System (ADS)

The Levenberg-Marquardt algorithm [1, 2] provides a numerical iterative solution to the problem of minimization of a function over a space of its parameters. In our work, the Levenberg-Marquardt algorithm retrieves optical parameters of a thin (single scattering) plane parallel atmosphere irradiated by collimated infinitely wide monochromatic beam of light. Black ground surface is assumed. Computational accuracy, sensitivity to the initial guess and the presence of noise in the signal, and other properties of the algorithm are investigated in scalar (using intensity only) and vector (including polarization) modes. We consider an atmosphere that contains a mixture of coarse and fine fractions. Following [3], the fractions are simulated using Henyey-Greenstein model. Though not realistic, this assumption is very convenient for tests [4, p.354]. In our case it yields analytical evaluation of Jacobian matrix. Assuming the MISR geometry of observation [5] as an example, the average scattering cosines and the ratio of coarse and fine fractions, the atmosphere optical depth, and the single scattering albedo, are the five parameters to be determined numerically. In our implementation of the algorithm, the system of five linear equations is solved using the fast Cramer's rule [6]. A simple subroutine developed by the authors, makes the algorithm independent from external libraries. All Fortran 90/95 codes discussed in the presentation will be available immediately after the meeting from sergey.v.korkin@nasa.gov by request. [1]. Levenberg K, A method for the solution of certain non-linear problems in least squares, Quarterly of Applied Mathematics, 1944, V.2, P.164-168. [2]. Marquardt D, An algorithm for least-squares estimation of nonlinear parameters, Journal on Applied Mathematics, 1963, V.11, N.2, P.431-441. [3]. Hovenier JW, Multiple scattering of polarized light in planetary atmospheres. Astronomy and Astrophysics, 1971, V.13, P.7 - 29. [4]. Mishchenko MI, Travis LD, and Lacis AA, Multiple scattering of light by particles, Cambridge: University Press, 2006. [5]. http://www-misr.jpl.nasa.gov/Mission/misrInstrument/ [6]. Habgood K, Arel I, Revisiting Cramer's rule for solving dense linear systems, In: Proceedings of the 2010 Spring Simulation Multiconference, Paper No 82. ISBN: 978-1-4503-0069-8. DOI: 10.1145/1878537.1878623.

Korkin, S.; Lyapustin, A.

2012-12-01

122

Atmospheric correction algorithm for NOAA-AVHRR products - Theory and application  

NASA Technical Reports Server (NTRS)

The present evaluation of the effects of atmospheric constituents on NOAA AVHRR visible and near-IR data first gives attention to the general remote sensing equation and then addresses the magnitude of the atmospheric effects for AVHRR solar bands with respect to their impact on the normalized difference vegetation index (NDVI) and the surface bidirectional reflectance. Possible approaches to the acquisition of atmospheric data are then considered, and examples of atmospheric correction of surface reflectance and NDVI are discussed. The correction of the aerosol effect is essential in the case of NDVI study of densely vegetated areas.

Tanre, Didier; Holben, Brent N.; Kaufman, Yoram J.

1992-01-01

123

Atmosphere  

NSDL National Science Digital Library

What is this atmosphere that surrounds the Earth? This instructional tutorial, part of an interactive laboratory series for grades 8-12, introduces students to the structure, effects, and components of the atmosphere. Here students investigate the composition of the atmosphere; effects of temperature, pressure, and ozone; the greenhouse effect; and how Earth compares with other planets. Interactive activities present students with opportunities to explore ideas and answer questions about the atmosphere, including its structure, the making of ozone, rocket launching, and measuring the atmosphere. Pop-up boxes provide additional information on topics such as dust, rain, and atmospheric composition. Students complete a final written review of six questions about the atmosphere. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

124

An Atmospheric Correction Algorithm for Remote Sensing of Bright Coastal Waters Using MODIS Land and Ocean Channels in the Solar Spectral Region  

Microsoft Academic Search

The present operational atmospheric correction algorithm for multichannel remote sensing of ocean color using imaging data acquired with the Moderate Resolution Imaging Spectroradiometer (MODIS) works well over clear ocean but can give incorrect results over brighter coastal waters. This is because: 1) the turbid waters are not dark for the two atmospheric correction channels centered near 0.75 and 0.86 mum;

Bo-Cai Gao; Marcos J. Montes; Rong-Rong Li; Heidi Melita Dierssen; Curtiss O. Davis

2007-01-01

125

Hybridization of hyperspectral imaging target detection algorithm chains  

E-print Network

matched filters OSP, and ASD. The chains generated by these algorithms will be compared using the Forest Radiance I HYDICE data set. Finally, receiver operating characteristic (ROC) curves will be calculated of the atmospheric compensation step is to convert the units of the scene from sensor reaching radiance

Kerekes, John

126

Compensation conundrum  

PubMed Central

Pressured by questions tabled in parliament that point to a lack of adequate enforcement of regulations, the DCG(I) has abruptly initiated action to ensure payment of compensation for trial-related injuries. While it is astounding that non-compliance to the existing regulations could have gone unnoticed by quality assurance staff as well as by the ethics committees and the regulator, for over six years, sudden enforcement of the regulation has thrown up issues and challenges that are difficult to resolve in the absence of an adequately debated and thought-through guidance. In implementing regulations for suo moto compensation, India is seeking to establish a practice not previously tested elsewhere in the world. There is no doubt that industry must support the idea of putting patients first, but procedural considerations in fixing causality and determining the quantum of compensation promise to raise questions of morality, ethics, and jurisprudence that will not be easy to answer. PMID:22347695

Mukherjee, Shoibal

2012-01-01

127

Atmospheric correction algorithms for hyperspectral remote sensing data of land and ocean  

Microsoft Academic Search

Hyperspectral imaging data have been collected with different types of imaging spectrometers from aircraft and satellite platforms since the mid-1980s. Because the solar radiation on the sun-surface-sensor path in the 0.42.5m visible and near-IR spectral regions is subject to absorption and scattering by atmospheric gases and aerosols, the hyperspectral imaging data contains atmospheric effects. In order to use hyperspectral imaging

Bo-Cai Gao; Marcos J. Montes; Curtiss O. Davis; Alexander F. H. Goetz

2009-01-01

128

Atmospheric Sensitivity to Spectral Top-of-Atmosphere Solar Irradiance Perturbations, Using MODTRAN-5 Radiative Transfer Algorithm  

NASA Astrophysics Data System (ADS)

The opportunity to insert state-of-the-art solar irradiance measurements and calculations, with subtle perturbations, into a narrow spectral resolution radiative transfer model has recently been facilitated through release of MODTRAN-5 (MOD5). The new solar data are from: (1) SORCE satellite measurements of solar variability over solar rotation cycle, & (2) ultra-narrow calculation of a new solar source irradiance, extending over the full MOD5 spectral range, from 0.2 um to far-IR. MODTRAN-5, MODerate resolution radiance and TRANsmittance code, has been developed collaboratively by Air Force Research Laboratory and Spectral Sciences, Inc., with history dating back to LOWTRAN. It includes approximations for all local thermodynamic equilibrium terms associated with molecular, cloud, aerosol and surface components for emission, scattering, and reflectance, including multiple scattering, refraction and a statistical implementation of Correlated-k averaging. The band model is based on 0.1 cm-1 (also 1.0, 5.0 and 15.0 cm-1 statistical binning for line centers within the interval, captured through an exact formulation of the full Voigt line shape. Spectroscopic parameters are from HITRAN 2004 with user-defined options for additional gases. Recent validation studies show MOD5 replicates line-by-line brightness temperatures to within ~0.02K average and <1.0K RMS. MOD5 can then serve as a surrogate for a variety of perturbation studies, including the two modes for the solar source function, Io. (1) Data from the Solar Radiation and Climate Experiment (SORCE) satellite mission provide state-of-the-art measurements of UV, visible, near-IR, plus total solar radiation, on near real-time basis. These internally consistent estimates of Sun's output over solar rotation and longer time scales are valuable inputs for studying effects of Sun's radiation on Earth's atmosphere and climate. When solar rotation encounters bright plage and dark sunspots, relative variations are expected to be very small in visible wavelengths, although absolute power is substantial. SORCE's Spectral Irradiance Monitor measurements are readily included in comparative MOD5 calculations. (2) The embedded solar irradiance within MOD5 must be compatible with the chosen band model resolution binning. By matching resolutions some issues related to the correlated-k band model parameterizations can be tested. Two high resolution solar irradiances, the MOD5 default irradiance (Kurucz) and a new compilation associated with Solar Radiation Physical Modeling project (Fontenla), are compared to address the potential impact of discrepancies between any sets of irradiances. The magnitude of solar variability, as measured and calculated, can lead to subtle changes in heating/cooling rates throughout the atmosphere, as a function of altitude and wavelength. By holding chemical & dynamical responses constant, only controlled distributions of absorbing gases, aerosols and clouds will contribute to observed 1st order radiative effects.

Anderson, G.; Berk, A.; Harder, G.; Fontenla, J.; Shettle, E.; Pilewski, P.; Kindel, B.; Chetwynd, J.; Gardner, J.; Hoke, M.; Jordan, A.; Lockwood, R.; Felde, G.; Archarya, P.

2006-12-01

129

CEO Compensation  

E-print Network

This paper surveys the recent literature on CEO compensation. The rapid rise in CEO pay over the past 30 years has sparked an intense debate about the nature of the pay-setting process. Many view the high level of CEO ...

Frydman, Carola

130

Numerical advection algorithms and their role in atmospheric transport and chemistry models  

NASA Technical Reports Server (NTRS)

During the last 35 years, well over 100 algorithms for modeling advection processes have been described and tested. This review summarizes the development and improvements that have taken place. The nature of the errors caused by numerical approximation to the advection equation are highlighted. Then the particular devices that have been proposed to remedy these errors are discussed. The extensive literature comparing transport algorithms is reviewed. Although there is no clear cut 'best' algorithm, several conclusions can be made. Spectral and pseudospectral techniques consistently provide the highest degree of accuracy, but expense and difficulties assuring positive mixing ratios are serious drawbacks. Schemes which consider fluid slabs bounded by grid points (volume schemes), rather than the simple specification of constituent values at the grid points, provide accurate positive definite results.

Rood, Richard B.

1987-01-01

131

A time series algorithm for simultaneous retrieval of atmospheric aerosol and surface reflectance from MODIS  

Microsoft Academic Search

If given a consecutive set of images of the same region of the Earth obtained from space, an untrained human will easily solve many of the remote sensing problems, such as selecting clear-skies areas, identifying clouds, distinguishing between clear and hazy conditions, and so on. What, in contrast to our brain's work, is missing in our algorithms, armed with the

A. Lyapustin; Y. Wang

2009-01-01

132

Simultaneous Retrieval of Temperature, Water Vapor and Ozone Atmospheric Profiles from IASI: Compression, De-noising, First Guess Retrieval and Inversion Algorithms  

NASA Technical Reports Server (NTRS)

A fast temperature water vapor and ozone atmospheric profile retrieval algorithm is developed for the high spectral resolution Infrared Atmospheric Sounding Interferometer (IASI) space-borne instrument. Compression and de-noising of IASI observations are performed using Principal Component Analysis. This preprocessing methodology also allows, for a fast pattern recognition in a climatological data set to obtain a first guess. Then, a neural network using first guess information is developed to retrieve simultaneously temperature, water vapor and ozone atmospheric profiles. The performance of the resulting fast and accurate inverse model is evaluated with a large diversified data set of radiosondes atmospheres including rare events.

Aires, F.; Rossow, W. B.; Scott, N. A.; Chedin, A.; Hansen, James E. (Technical Monitor)

2001-01-01

133

Development of an operational algorithm for removing atmospheric effects from HYDICE and HSI data  

Microsoft Academic Search

Spectral imaging data have been acquired with the Navy HYDICE (the hyperspectral digital imagery collection experiment) instrument from an aircraft. Similar data will soon be collected with the NASA HSI instrument from the Lewis spacecraft. The majority of users of imaging spectrometer data are interested in studying surface properties. Therefore, atmospheric absorption and scattering effects must be removed from imaging

Bo-Cai Gao; Curtiss O. Davis

1996-01-01

134

Executive Compensation  

Microsoft Academic Search

This paper summarizes the empirical and theoretical research on executive compensation and provides a comprehensive and up-to-date description of pay practices (and trends in pay practices) for chief executive officers (CEOs). Topics discussed include the level and structure of CEO pay (including detailed analyses of annual bonus plans, executive stock options, and option valuation), international pay differences, the pay-setting process,

Kevin J. Murphy

135

Executive Compensation  

Microsoft Academic Search

This paper summarizes the empirical and theoretical research on executive compensation and provides a comprehensive and up-to-date description of pay practices (and trends in pay practices) for chief executive officers (CEOs). Topics discussed include the level and structure of CEO pay (including detailed analyses of annual bonus plans, executive stock options, and option valuation), international pay differences, the pay-setting process,

Kevin J. Murphy

1999-01-01

136

A snow\\/atmosphere physical parameter algorithm for the GCOM-C1\\/SGLI sensor  

Microsoft Academic Search

The Global Change Observation Mission-Climate\\/Second-generation Global Imager (GCOM-C1\\/SGLI) is scheduled to be launched in 2014. The SGLI instrument has two major new features: 250 m spatial resolution and polarization\\/multidirectional observation capabilities. The 250 m resolution provides enhanced observation capability over snow\\/ice\\/mountain areas which are difficult to access. The multidirectional observations with polarization channels have the potential to do accurate snow\\/atmosphere

T. Tanikawa; N. Chen; Y. Fan; W. Li; K. H. Stamnes

2010-01-01

137

Translational motion compensation in ISAR image processing  

Microsoft Academic Search

In inverse synthetic aperture radar (ISAR) imaging, the target rotational motion with respect to the radar line of sight contributes to the imaging ability, whereas the translational motion must be compensated out. This paper presents a novel two-step approach to translational motion compensation using an adaptive range tracking method for range bin alignment and a recursive multiple-scatterer algorithm (RMSA) for

Haiqing Wu; Dominic Grenier; Gilles Y. Delisle; Da-Gang Fang

1995-01-01

138

Influence of the compensating anions of Ni\\/Al and Ni\\/Mg\\/Al layered double hydroxides on their activation under oxidising and reducing atmospheres  

Microsoft Academic Search

The activities and selectivities in the hydrogenation of acetonitrile on catalysts obtained from Ni\\/Al and Ni\\/Mg\\/Al layered double hydroxides (LDHs) precursors depend on the nature of their compensating anions: CO2?3,NO?3 or Cl?. The latter gives rise to sample with low activity and the less selective to primary amine. Studies by XRD, TGDSC, mass spectrometry and TPR experiments show that the

Olga Lebedeva; Didier Tichit; Bernard Coq

1999-01-01

139

Improved Determination of Surface and Atmospheric Temperatures Using Only Shortwave AIRS Channels: The AIRS Version 6 Retrieval Algorithm  

NASA Technical Reports Server (NTRS)

AIRS was launched on EOS Aqua on May 4, 2002 together with ASMU-A and HSB to form a next generation polar orbiting infrared and microwave atmosphere sounding system (Pagano et al 2003). The theoretical approach used to analyze AIRS/AMSU/HSB data in the presence of clouds in the AIRS Science Team Version 3 at-launch algorithm, and that used in the Version 4 post-launch algorithm, have been published previously. Significant theoretical and practical improvements have been made in the analysis of AIRS/AMSU data since the Version 4 algorithm. Most of these have already been incorporated in the AIRS Science Team Version 5 algorithm (Susskind et al 2010), now being used operationally at the Goddard DISC. The AIRS Version 5 retrieval algorithm contains three significant improvements over Version 4. Improved physics in Version 5 allowed for use of AIRS clear column radiances (R(sub i)) in the entire 4.3 micron CO2 absorption band in the retrieval of temperature profiles T(p) during both day and night. Tropospheric sounding 15 micron CO2 observations were used primarily in the generation of clear column radiances (R(sub i)) for all channels. This new approach allowed for the generation of accurate Quality Controlled values of R(sub i) and T(p) under more stressing cloud conditions. Secondly, Version 5 contained a new methodology to provide accurate case-by-case error estimates for retrieved geophysical parameters and for channel-by-channel clear column radiances. Thresholds of these error estimates are used in a new approach for Quality Control. Finally, Version 5 contained for the first time an approach to provide AIRS soundings in partially cloudy conditions that does not require use of any microwave data. This new AIRS Only sounding methodology was developed as a backup to AIRS Version 5 should the AMSU-A instrument fail. Susskind et al 2010 shows that Version 5 AIRS Only sounding are only slightly degraded from the AIRS/AMSU soundings, even at large fractional cloud cover.

Susskind, Joel; Blaisdell, John; Iredell, Lena

2010-01-01

140

A new atmospheric ray-tracing algorithm and its use in VLBI analysis  

NASA Astrophysics Data System (ADS)

Due to recent improvements of numerical weather models (NWM), ray-tracing has become an interesting and feasible method for different scientific purposes. One application in geosciences is the estimation of tropospheric delays for the correction of space geodetic techniques. Here, we present and discuss the recently developed ray-tracing algorithm from the Institute of Geodesy and Geophysics (IGG) at Vienna University of Technology. We use numerical weather model data from the European Centre for Medium-Range Weather Forecasts (ECMWF) to estimate the tropospheric total delay by solving the Eikonal equation. In addition we discuss different methods and characteristics, such as interpolation methods, resolution of the data set and the use of different refractivity constants, and we present results and differences between a 2D- and 3D-ray-tracing algorithm. As quality validation we enter the derived tropospheric delays as a priori information in our VLBI analysis software package (Vienna VLBI Software). We analyze IVS Intensive sessions from July 2010 to October 2011 which are carried out for the estimation of UT1-UTC (DUT1). The measurement of this Earth rotation angle is needed in near real-time for the accurate prediction of Universal Time (UT1) as well as for navigation purposes. Due to the small number of observables per session most parameters, which are usually estimated in VLBI analyses, are fixed to their a priori values, which should be known as accurately as possible. As an external validation of our ray-traced delays we calculate Length-of-Day (LoD) from the VLBI-derived DUT1 values and compare these to LoD from GPS.

Madzak, M.; Nafisi, V.; Bhm, J.; Schuh, H.

2012-04-01

141

Targeting Atmospheric Simulation Algorithms for Large Distributed Memory GPU Accelerated Computers  

SciTech Connect

Computing platforms are increasingly moving to accelerated architectures, and here we deal particularly with GPUs. In [15], a method was developed for atmospheric simulation to improve efficiency on large distributed memory machines by reducing communication demand and increasing the time step. Here, we improve upon this method to further target GPU accelerated platforms by reducing GPU memory accesses, removing a synchronization point, and better clustering computations. The modification ran over two times faster in some cases even though more computations were required, demonstrating the merit of improving memory handling on the GPU. Furthermore, we discover that the modification also has a near 100% hit rate in fast on-chip L1 cache and discuss the reasons for this. In concluding, we remark on further potential improvements to GPU efficiency.

Norman, Matthew R [ORNL

2013-01-01

142

An adaptive reduction algorithm for efficient chemical calculations in global atmospheric chemistry models  

NASA Astrophysics Data System (ADS)

We present a computationally efficient adaptive method for calculating the time evolution of the concentrations of chemical species in global 3-D models of atmospheric chemistry. Our strategy consists of partitioning the computational domain into fast and slow regions for each chemical species at every time step. In each grid box, we group the fast species and solve for their concentration in a coupled fashion. Concentrations of the slow species are calculated using a simple semi-implicit formula. Separation of species between fast and slow is done on the fly based on their local production and loss rates. This allows for example to exclude short-lived volatile organic compounds (VOCs) and their oxidation products from chemical calculations in the remote troposphere where their concentrations are negligible, letting the simulation determine the exclusion domain and allowing species to drop out individually from the coupled chemical calculation as their production/loss rates decline. We applied our method to a 1-year simulation of global tropospheric ozone-NO x-VOC-aerosol chemistry using the GEOS-Chem model. Results show a 50% improvement in computational performance for the chemical solver, with no significant added error.

Santillana, Mauricio; Le Sager, Philippe; Jacob, Daniel J.; Brenner, Michael P.

2010-11-01

143

A simplified guidance algorithm for lifting aeroassist orbital transfer vehicles  

NASA Technical Reports Server (NTRS)

The derivation, logic, and performance of a simplified atmospheric guidance algorithm for aeroassist orbital-transfer vehicles (AOTVs) are presented. The algorithm was developed to meet the demands for an aerobraking trajectory guidance technique that was uncomplicated, easily integrated into existing trajectory programs, adaptable to a range of vehicle aerodynamic configurations, capable of performance equivalent to currently available guidance programs in compensating for dispersions in entry conditions, atmospheric conditions, and aerodynamic characteristics. The result was a hybrid lifting guidance algorithm combining the method of reference-profile generation with the method of predictor/corrector schemes. The resulting performance is good (less than 3 n.m. error from desired apogee despite uncertainties of + or - 50 percent atmospheric density, + or - 0.2 deg entry flight-path angle, or + or - 50 percent L/D. Combinations of these same dispersions with lesser magnitudes have also been successful, although performance with density 'pockets' within the atmosphere requires more analysis.

Cerimele, C. J.; Gamble, J. D.

1985-01-01

144

Impact of mixing height estimation on heterogeneous terrains with different algorithms and instruments on atmospheric transport models.  

NASA Astrophysics Data System (ADS)

The retrieval of mixing height [MH] is a common target of several scientific community all over the world. A strong effort is needed to the fact that modeling of MH generally fails introducing strong errors in the estimate of the concentrations of pollutants and green house gasses within the boundary layer. In Europe local meteorological services and international projects are implementing networks of instruments that can provide atmospheric profiles of different quantities. These networks will continuously provide data which could be used to constrain MH values. The current availability of atmospheric profiles of different nature, such as radiosondes, ground based lidar and ceilometers as well as satellites over Europe grant a spatial coverage that allow to estimate the impact of the knowledge of MH on transport models at synoptic scale of quantities as CO2 and CH4 mixing ratios. In this study we apply several algorithms to retrieve MH from different data sources: the ceilometers network installed by the German Weather Service; the data from CALIPSO satellite and all the WMO radio-soundings available over Europe during the IMECC (Infrastructure for Measurements of the European Carbon Cycle) in 2009. The values obtained from the optical instruments are validated using as reference the estimation retrieved by the virtual potential temperature profiles obtained by the radiosondes where co-location occurs and using statistical interpolation to evaluate the estimates from satellite and non co-located stations.. The impact of this estimates of MH on CO2 mixing ratios will be evaluated with the Stochastic Time Inverted Lagrangian Transport model (STILT) driven by WRF meteorology in comparison with in-situ measurements.

Biavati, G.; Kretschmer, R.; Gerbig, C.; Feist, D. G.

2012-04-01

145

Hyperspectral material identification on radiance data using single-atmosphere or multiple-atmosphere modeling  

NASA Astrophysics Data System (ADS)

Reflectance-domain methods convert hyperspectral data from radiance to reflectance using an atmospheric compensation model. Material detection and identification are performed by comparing the compensated data to target reflectance spectra. We introduce two radiance-domain approaches, Single atmosphere Adaptive Cosine Estimator (SACE) and Multiple atmosphere ACE (MACE) in which the target reflectance spectra are instead converted into sensor-reaching radiance using physics-based models. For SACE, known illumination and atmospheric conditions are incorporated in a single atmospheric model. For MACE the conditions are unknown so the algorithm uses many atmospheric models to cover the range of environmental variability, and it approximates the result using a subspace model. This approach is sometimes called the invariant method, and requires the choice of a subspace dimension for the model. We compare these two radiance-domain approaches to a Reflectance-domain ACE (RACE) approach on a HYDICE image featuring concealed materials. All three algorithms use the ACE detector, and all three techniques are able to detect most of the hidden materials in the imagery. For MACE we observe a strong dependence on the choice of the material subspace dimension. Increasing this value can lead to a decline in performance.

Mariano, Adrian V.; Grossmann, John M.

2010-11-01

146

Radiation Exposure Compensation Program  

NSDL National Science Digital Library

This is the Justice Department's Radiation Exposure Compensation Program homepage. This site features information about the Radiation Exposure Compensation Act, including claimant categories, claim forms, and the Energy Employees Occupational Illness Compensation Program Act. This site also provides a table illustrating a summary of all claims received and compensation paid to date.

Program, U. S.

147

Reactive power compensating system  

DOEpatents

The reactive power of an induction machine is compensated by providing fixed capacitors on each phase line for the minimum compensation required, sensing the current on one line at the time its voltage crosses zero to determine the actual compensation required for each phase, and selecting switched capacitors on each line to provide the balance of the compensation required.

Williams, Timothy J. (Redondo Beach, CA); El-Sharkawi, Mohamed A. (Renton, WA); Venkata, Subrahmanyam S. (Seattle, WA)

1987-01-01

148

Measurements of ClONO2 by the Improved Limb Atmospheric Spectrometer (ILAS) in high-latitude stratosphere: New products using version 6.1 data processing algorithm  

Microsoft Academic Search

We report the first continuous measurements of chlorine nitrate (ClONO2) in high-latitude regions taken by the Improved Limb Atmospheric Spectrometer (ILAS) on board the Advanced Earth Observing Satellite (ADEOS) and processed using the latest data retrieval algorithm (version 6.1). Performance of the measurements, validation with three balloon-borne sensors, and seasonal variation of ClONO2 in the Arctic and Antarctic stratosphere are

H. Nakajima; T. Sugita; H. Irie; N. Saitoh; H. Kanzawa; H. Oelhaf; G. Wetzel; G. C. Toon; B. Sen; J.-F. Blavier; W. A. Traub; K. Jucks; D. G. Johnson; T. Yokota; Y. Sasano

2006-01-01

149

Improved air-sea flux algorithms in an ocean-atmosphere coupled model for simulation of global ocean SST and its tropical Pacific variability  

NASA Astrophysics Data System (ADS)

A revised algorithm for air-sea exchange parameterization of momentum, sensible and latent heat flux improves the climate simulation of the global distribution of sea surface temperature (SST) and tropical Pacific variability of SST. Based upon an analysis of studies from field programs, we apply the revised algorithm with new expressions for surface momentum and scalar roughness length dependent on 10-m winds in neutral condition, and evaluate them in the ocean-atmosphere coupled model of the Australian Community Climate and Earth-System Simulator. The revised algorithm improves simulations for mean global SST distribution, demonstrated with Pearson's correlation indices showing corrections to a net fraction of 28 % over the global oceans. Being focused on the tropical Pacific, the algorithm eases the tropical SST cold tongue bias, and improves predictability of ENSO variability with better representations of the standard deviation of the Nino-3.4 index, especially the skewness of the index for nonlinearity of ENSO variability. Bjerknes and thermodynamical feedbacks are applied to understand the effects of the revised algorithm on the predictability of the Nino indices.

Ma, Yimin; Zhou, Xiaobing; Bi, Daohua; Sun, Zhian; Hirst, Anthony C.

2014-08-01

150

Ecomp Executive Compensation Database  

NSDL National Science Digital Library

The Ecomp Executive Compensation Database allows users to research the compensation and net-worth of executives. Users may search the database by company name or ticker symbol, as well as by state, sector, and industry pull-down menus. Search returns list compensation summaries for the top executives, including salary, bonus, and total compensation. Clicking on the executive's name will give a more detailed summary, including restricted stock, LTIP payouts, and value realized for options exercised. All numbers are for 1999.

151

Compensation and Conservation.  

ERIC Educational Resources Information Center

Although the idea that conservation can occur without compensation was rejected by Piaget, direct and indirect evidence from developmental studies and conservation training research indicates that conservation can and does develop without compensation. Nevertheless, adults' conservation concepts include the compensation principle and influence

Silverman, Irwin W.; Rose, Arthur P.

1982-01-01

152

75 FR 48274 - Radiation Exposure Compensation Act: Allowance for Costs and Expenses  

Federal Register 2010, 2011, 2012, 2013

...claims pending with the Radiation Exposure Compensation Act...1990, Congress passed the Radiation Exposure Compensation Act...diseases following exposure to radiation released during above-ground atmospheric nuclear weapons tests or...

2010-08-10

153

TRADE LIBERALIZATION AND COMPENSATION ?  

E-print Network

Liberalization harms some groups while generating aggregate benefits. We consider various labor market policies that might be used to compensate those who lose from freer trade. Our goal is to find the policy that compensates each group of losers at the lowest cost to the economy. We argue that wage subsidies should be used to compensate those who bear the adjustment costs triggered by liberalization whereas employment subsidies should be used to compensate those who remain trapped in the previously protected sector. Our analysis indicates that the cost of compensation is low, provided that the right policy is used. 1.

Davidson; Steven J. Matusz

154

Entry vehicle performance analysis and atmospheric guidance algorithm for precision landing on Mars. M.S. Thesis - Massachusetts Inst. of Technology  

NASA Technical Reports Server (NTRS)

Future missions to Mars may require pin-point landing precision, possibly on the order of tens of meters. The ability to reach a target while meeting a dynamic pressure constraint to ensure safe parachute deployment is complicated at Mars by low atmospheric density, high atmospheric uncertainty, and the desire to employ only bank angle control. The vehicle aerodynamic performance requirements and guidance necessary for 0.5 to 1.5 lift drag ratio vehicle to maximize the achievable footprint while meeting the constraints are examined. A parametric study of the various factors related to entry vehicle performance in the Mars environment is undertaken to develop general vehicle aerodynamic design requirements. The combination of low lift drag ratio and low atmospheric density at Mars result in a large phugoid motion involving the dynamic pressure which complicates trajectory control. Vehicle ballistic coefficient is demonstrated to be the predominant characteristic affecting final dynamic pressure. Additionally, a speed brake is shown to be ineffective at reducing the final dynamic pressure. An adaptive precision entry atmospheric guidance scheme is presented. The guidance uses a numeric predictor-corrector algorithm to control downrange, an azimuth controller to govern crossrange, and analytic control law to reduce the final dynamic pressure. Guidance performance is tested against a variety of dispersions, and the results from selected tests are presented. Precision entry using bank angle control only is demonstrated to be feasible at Mars.

Dieriam, Todd A.

1990-01-01

155

Adaptive compensation of sensor runout and mass unbalance in magnetic bearing systems  

Microsoft Academic Search

This paper presents two algorithms: one for sensor runout compensation, and the other for compensation of both sensor runout and mass unbalance in magnetic bearings. The algorithms, developed using Lyapunov's method, guarantee asymptotic stability of the rotor geometric center about the origin and convergence of unknown parameters using persistent excitation. Both algorithms have advantages over existing methods. Simulation results are

Joga D. Setiawan; Ranjan Mukherjee; Eric H. Maslen; Gangbing Song

1999-01-01

156

Combined Infrared and Microwave Retrievals of Atmospheric Profiles in the Presence of Clouds using Nonlinear Stochastic Methods: The SCENE Algorithm  

Microsoft Academic Search

A nonlinear stochastic method for the retrieval of atmospheric temperature and moisture profiles has been devel- oped and evaluated with sounding data from the Atmospheric InfraRed Sounder (AIRS) and the Advanced Microwave Sound- ing Unit (AMSU), and is presently being adapted for use with the NPOESS Cross-track Infrared Microwave Sounding Suite (CrIMSS) consisting of the Cross-track Infrared Sounder (CrIS) and

William J. Blackwell; Frederick W. Chen

2006-01-01

157

The Algorithm Theoretical Basis Document for the Atmospheric Delay Correction to GLAS Laser Altimeter Ranges. Volume 8  

NASA Technical Reports Server (NTRS)

NASA s Ice, Cloud, and Land Elevation Satellite (ICESat) mission will be launched late 2001. It s primary instrument is the Geoscience Laser Altimeter System (GLAS) instrument. The main purpose of this instrument is to measure elevation changes of the Greenland and Antarctic icesheets. To accurately measure the ranges it is necessary to correct for the atmospheric delay of the laser pulses. The atmospheric delay depends on the integral of the refractive index along the path that the laser pulse travels through the atmosphere. The refractive index of air at optical wavelengths is a function of density and molecular composition. For ray paths near zenith and closed form equations for the refractivity, the atmospheric delay can be shown to be directly related to surface pressure and total column precipitable water vapor. For ray paths off zenith a mapping function relates the delay to the zenith delay. The closed form equations for refractivity recommended by the International Union of Geodesy and Geophysics (IUGG) are optimized for ground based geodesy techniques and in the next section we will consider whether these equations are suitable for satellite laser altimetry.

Herring, Thomas A.; Quinn, Katherine J.

2012-01-01

158

Allpass filter design with waveguide loss compensation.  

PubMed

A major artifact of realistic photonic filters is the waveguide power loss. Its detrimental effect on the allpass structure is particularly alarming because the phase response is highly sensitive to perturbations. While the loss can be simply captured into a variation on the unit delay in signal processing analysis, its non-linearity makes it mathematically difficult to address. We present an allpass filter design algorithm that is able to provide filter coefficients that compensate for the waveguide power loss. By absorbing the loss parameter into the design cost function, the optimization problem becomes non-convex and NP hard. Our approach solves this problem by utilizing an iterative algorithm in conjunction with the branch and bound global optimization technique. The proposed algorithm is expected to improve the performance and increase the utilization of allpass filters for optical signal phase based applications such as distortion compensation and group delay equalization. PMID:24514799

Wang, Yujia; Grieco, Andrew; Nguyen, Truong

2013-12-30

159

The "dual-spot" Aethalometer: an improved measurement of aerosol black carbon with real-time loading compensation  

NASA Astrophysics Data System (ADS)

Aerosol black carbon is a unique primary tracer for combustion emissions. It affects the optical properties of the atmosphere and is recognized as the second most important anthropogenic forcing agent for climate change. It is the primary tracer for adverse health effects caused by air pollution. For the accurate determination of mass equivalent black carbon concentrations in the air and for source apportionment of the concentrations, optical measurements by filter-based absorption photometers must take into account the "filter loading effect". We present a new real-time loading effect compensation algorithm based on a two parallel spot measurement of optical absorption. This algorithm has been incorporated into the new Aethalometer model AE33. Intercomparison studies show excellent reproducibility of the AE33 measurements and very good agreement with post-processed data obtained using earlier Aethalometer models, and other filter-based absorption photometers. The real-time loading effect compensation algorithm provides the high-quality data necessary for real-time source apportionment, and for determination of the temporal variation of the compensation parameter k.

Drinovec, L.; Mo?nik, G.; Zotter, P.; Prvt, A. S. H.; Ruckstuhl, C.; Coz, E.; Rupakheti, M.; Sciare, J.; Mller, T.; Wiedensohler, A.; Hansen, A. D. A.

2014-09-01

160

Realtime motion compensation for ROV-based tele-operated underwater manipulators  

Microsoft Academic Search

This paper presents a novel underwater movement compensation algorithm for stabilization of manipulator position utilizing not ROV movements for disturbance compensation, but overlaid manipulator movements. A model based estimator is used to predict vehicle movement and provide the manipulation system with the necessary time to compensate for the estimated motion. It describes the conceptual benefits of this approach compared with

Marc Hildebrandt; Leif Christensen; Jochen Kerdels; Jan Albiez; Frank Kirchner

2009-01-01

161

Unbalance vibratory displacement compensation for active magnetic bearings  

NASA Astrophysics Data System (ADS)

As the dynamic stiffness of radial magnetic bearings is not big enough, when the rotor spins at high speed, unbalance displacement vibration phenomenon will be produced. The most effective way for reducing the displacement vibration is to enhance the radial magnetic bearing stiffness through increasing the control currents, but the suitable control currents are not easy to be provided, especially, to be provided in real time. To implement real time unbalance displacement vibration compensation, through analyzing active magnetic bearings (AMB) mathematical model, the existence of radial displacement runout is demonstrated. To restrain the runout, a new control scheme-adaptive iterative learning control (AILC) is proposed in view of rotor frequency periodic uncertainties during the startup process. The previous error signal is added into AILC learning law to enhance the convergence speed, and an impacting factor ? influenced by the rotor rotating frequency is introduced as learning output coefficient to improve the rotor control effects. As a feed-forward compensation controller, AILC can provide one unknown and perfect compensatory signal to make the rotor rotate around its geometric axis through power amplifier and radial magnetic bearings. To improve AMB closed-loop control system robust stability, one kind of incomplete differential PID feedback controller is adopted. The correctness of the AILC algorithm is validated by the simulation of AMB mathematical model adding AILC compensation algorithm through MATLAB soft. And the compensation for fixed rotational frequency is implemented in the actual AMB system. The simulation and experiment results show that the compensation scheme based on AILC algorithm as feed-forward compensation and PID algorithm as close-loop control can realize AMB system displacement minimum compensation at one fixed frequency, and improve the stability of the control system. The proposed research provides a new adaptive iterative learning control algorithm and control strategy for AMB displacement minimum compensation, and provides some references for time-varied displacement minimum compensation.

Gao, Hui; Xu, Longxiang; Zhu, Yili

2013-01-01

162

Incentive compensation : bonusing and motivation  

E-print Network

Management is often frustrated by the lack of motivation generated by end of the year bonuses. Currently, there are two compensation ideals, merit-based versus incentive-based. Merit based compensation correlates compensation ...

Wang, Shun Linda, 1980-

2004-01-01

163

An improvement to the volcano-scan algorithm for atmospheric correction of CRISM and OMEGA spectral data  

E-print Network

The observations of Mars by the CRISM and OMEGA hyperspectral imaging spectrometers require correction for photometric, atmospheric and thermal effects prior to the interpretation of possible mineralogical features in the spectra. Here, we report on a simple, yet non-trivial, adaptation to the commonly-used volcano-scan correction technique for atmospheric CO_2, which allows for the improved detection of minerals with intrinsic absorption bands at wavelengths between 1.9-2.1 $\\mu$m. This volcano-scan technique removes the absorption bands of CO_2 by ensuring that the Lambert albedo is the same at two wavelengths: 1.890 $\\mu$m and 2.011 $\\mu$m, with the first wavelength outside the CO_2 gas bands and the second wavelength deep inside the CO_2 gas bands. Our adaptation to the volcano-scan technique moves the first wavelength from 1.890 $\\mu$m to be instead within the gas bands at 1.980 $\\mu$m, and for CRISM data, our adaptation shifts the second wavelength slightly, to 2.007 $\\mu$m. We also report on our effort...

McGuire, Patrick C; Brown, Adrian J; Fraeman, Abigail A; Marzo, Giuseppe A; Morgan, M Frank; Murchie, Scott L; Mustard, John F; Parente, Mario; Pelkey, Shannon M; Roush, Ted L; Seelos, Frank P; Smith, Michael D; Wendt, Lorenz; Wolff, Michael J

2009-01-01

164

Reactive Power Compensator.  

DOEpatents

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation. 26 figs.

El-Sharkawi, M.A.; Venkata, S.S.; Chen, M.; Andexler, G.; Huang, T.

1992-07-28

165

Reactive power compensator  

DOEpatents

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

El-Sharkawi, Mohamed A. (Renton, WA); Venkata, Subrahmanyam S. (Woodinville, WA); Chen, Mingliang (Kirkland, WA); Andexler, George (Everett, WA); Huang, Tony (Seattle, WA)

1992-01-01

166

Retrieving water surface temperature from archive LANDSAT thermal infrared data: Application of the mono-channel atmospheric correction algorithm over two freshwater reservoirs  

NASA Astrophysics Data System (ADS)

Water surface temperature is a key element in characterizing the thermodynamics of waterbodies, and for irregularly-shaped inland reservoirs, LANDSAT thermal infrared images are the best alternative yet for the retrieval of this parameter. However, images must be corrected mainly for atmospheric effects in order to be fully exploitable. The objective of this study is to validate the mono-channel correction algorithm for single-band thermal infrared LANDSAT data as put forward by Jimnez-Muoz et al. (2009). Two freshwater reservoirs in continental France were selected as study sites, and best use was made of all accessible image and field data. Results obtained are satisfactory and in accordance with the literature: r2 values are above 0.90 and root-mean-square error values are comprised between 1 and 2 C. Moreover, paired Wilcoxon signed rank tests showed a highly significant difference between field and uncorrected image data, a very highly significant difference between uncorrected and corrected image data, and no significant difference between field and corrected image data. The mono-channel algorithm is hence recommended for correcting archive LANDSAT single-band thermal infrared data for inland waterbody monitoring and study.

Simon, R. N.; Tormos, T.; Danis, P.-A.

2014-08-01

167

Clouds and the Earth's Radiant Energy System (CERES) Algorithm Theoretical Basis Document. Volume 3; Cloud Analyses and Determination of Improved Top of Atmosphere Fluxes (Subsystem 4)  

NASA Technical Reports Server (NTRS)

The theoretical bases for the Release 1 algorithms that will be used to process satellite data for investigation of the Clouds and Earth's Radiant Energy System (CERES) are described. The architecture for software implementation of the methodologies is outlined. Volume 3 details the advanced CERES methods for performing scene identification and inverting each CERES scanner radiance to a top-of-the-atmosphere (TOA) flux. CERES determines cloud fraction, height, phase, effective particle size, layering, and thickness from high-resolution, multispectral imager data. CERES derives cloud properties for each pixel of the Tropical Rainfall Measuring Mission (TRMM) visible and infrared scanner and the Earth Observing System (EOS) moderate-resolution imaging spectroradiometer. Cloud properties for each imager pixel are convolved with the CERES footprint point spread function to produce average cloud properties for each CERES scanner radiance. The mean cloud properties are used to determine an angular distribution model (ADM) to convert each CERES radiance to a TOA flux. The TOA fluxes are used in simple parameterization to derive surface radiative fluxes. This state-of-the-art cloud-radiation product will be used to substantially improve our understanding of the complex relationship between clouds and the radiation budget of the Earth-atmosphere system.

1995-01-01

168

Measurement of Small Values of Hydrostatic Pressure with the Compensation of Atmospheric Pressure Influence / Pomiar Ma?ych Warto?ci Ci?nienia Hydrostatycznego Z Kompensacj? Wp?ywu Ci?nienia Atmosferycznego  

NASA Astrophysics Data System (ADS)

Knowledge of pressure distribution (or differential pressure ) determines the fluid flow description through the porous medium. In the case of big Reynolds numbers it is not difficult, but for laminar flows (i.e. for Re numbers Bear, 1988; Duckworth, 1983; Troskola?ski, 1957) from the scope 0.01 to 3) this description is virtually impossible on the basis of the tools available on the market. The previous study (Broda & Filipek, 2012) focused on the difficulty of measurement in the case of small differences of pressure and suggested a new original method for the measurement. A new unit for the measurement was constructed consisting of two separate measurement containers. Then the measurements were conducted, which necessitated temperature stabilization of the device and compensation of the atmospheric pressure influence on the measurement process. This paper presents the results of the continuation of research concerning the methods and equipment for the measurement of very small pressure differences. The paper includes also the experience gained from the new measurement unit, which was presented in figures 1-5 subsequently presenting the concept of measurement of small values of hydrodynamic pressure with compensation of atmospheric pressure influence fig. 1; illustration presenting the state corresponding to the case of the lack of flow through the tested item fig 2; state corresponding to the fluid flow through the tested item fig. 3; then the description of the measurement of pressure drop on the tested item fig. 4 and the measurement methodology (relations (1) - (20)). Picture of the measurement unit and its components - fig. 5. Furthermore, the authors present an exemplary measurement series and focus on the method of measurement and data processing - tables 1-8 and figures 6-8. Table 4 presents the comparison of the measurement unit used in the previous research (Broda & Filipek, 2012) and the new one - presented in the paper. It should be noted that the structure has been simplified and the measurement accuracy has increased. Znajomo?? rozk?adu ci?nienia (lub r?nicy ci?nie?) determinuje opis przep?ywu p?ynu przez o?rodek porowaty. W przypadku du?ych liczb Reynoldsa nie nastr?cza to wi?kszych trudno?ci, lecz dla przep?yww laminarnych (tj. dla liczb Re (Bear, 1988; Duckworth, 1983; Troskola?ski, 1957) z zakresu 0.01 do 3) jest to praktycznie niemo?liwe w oparciu o dost?pne na rynku przyrz?dy. Przyczyny powoduj?ce tak? sytuacj? zosta?y omwione w poprzednim opracowaniu (Broda i Filipek, 2012), w ktrym zwrcono uwag? na trudno?ci pomiarw zwi?zane z napi?ciem powierzchniowym czy w?oskowato?ci? (Adamson, 1997). Zaproponowano (Broda i Filipek, 2012) now?, autorsk? metod? pomiaru bardzo ma?ych r?nic ci?nie? oraz skonstruowano odpowiednie stanowisko sk?adaj?ce si? z dwch oddzielnych zbiornikw pomiarowych oraz przeprowadzono pomiary. Z przeprowadzonych bada? (Broda i Filipek, 2012) wynika?a konieczno?? zastosowania stabilizacji temperatury urz?dzenia oraz kompensacji wp?ywu ci?nienia atmosferycznego na proces pomiarowy. Niniejsza publikacja przedstawia wyniki kontynuacji bada? nad metodami i aparatur? do pomiaru bardzo ma?ych r?nic ci?nie? z uwzgl?dnieniem zdobytych do?wiadcze?, w oparciu o nowe stanowisko pomiarowe, ktrego zasad? dzia?ania i budow? przedstawiono na rys. 1-5, kolejno przedstawiaj?c koncepcj? wykonania pomiaru ma?ych warto?ci ci?nienia hydrodynamicznego z kompensacj? wp?ywu ci?nienia atmosferycznego rys. 1; ilustracj? obrazuj?c? stan odpowiadaj?cy przypadkowi braku przep?ywu p?ynu przez badany obiekt rys. 2; omawiaj?c stan odpowiadaj?cy przypadkowi przep?ywu p?ynu przez badany obiekt rys. 3. Kolejno omwiono stan odpowiadaj?cy pomiarowi spadku ci?nienia na badanym obiekcie rys. 4 oraz przedstawiono metodyk? pomiaru (zale?no?ci (1) - (20)). Zdj?cie stanowiska badawczego oraz jego elementw ilustruje rys. 5. W dalszej cz??ci artyku?u autorzy przedstawiaj? przyk?adow? seri? pomiarow? zwracaj

Broda, Krzysztof; Filipek, Wiktor

2013-09-01

169

Temperature Effects and Compensation-Control Methods  

PubMed Central

In the analysis of the effects of temperature on the performance of microgyroscopes, it is found that the resonant frequency of the microgyroscope decreases linearly as the temperature increases, and the quality factor changes drastically at low temperatures. Moreover, the zero bias changes greatly with temperature variations. To reduce the temperature effects on the microgyroscope, temperature compensation-control methods are proposed. In the first place, a BP (Back Propagation) neural network and polynomial fitting are utilized for building the temperature model of the microgyroscope. Considering the simplicity and real-time requirements, piecewise polynomial fitting is applied in the temperature compensation system. Then, an integral-separated PID (Proportion Integration Differentiation) control algorithm is adopted in the temperature control system, which can stabilize the temperature inside the microgyrocope in pursuing its optimal performance. Experimental results reveal that the combination of microgyroscope temperature compensation and control methods is both realizable and effective in a miniaturized microgyroscope prototype. PMID:22408509

Xia, Dunzhu; Chen, Shuling; Wang, Shourong; Li, Hongsheng

2009-01-01

170

Iterative springback compensation of NUMISHEET benchmark ?1  

NASA Astrophysics Data System (ADS)

Upon unloading after the forming stage, a sheet metal product will spring back due to internal stresses. Springback is a major problem for process-planning engineers. In industrial practise, deformations due to springback are compensated manually, by doing extensive measurements on prototype parts, and altering the tool geometry by hand. This is a time consuming and costly operation. In this paper the application of two compensation algorithms, based on the finite element simulation of the forming process are discussed. The smooth displacement adjustment (SDA) method and the springforward (SF) method have been applied to several industrial products, such as the NUMISHEET 2005 benchmark?1. With the SDA method successful compensations have been carried out. For the SF method some principal problems remain.

Lingbeek, R. A.; Hutink, J.; Ohnimus, S.; Weiher, J.

2005-08-01

171

Use of the Advanced Canopy-Atmosphere-Soil Algorithm (ACASA) model to determine flux quality and gap-fill nighttime data at multiple AmeriFlux sites  

NASA Astrophysics Data System (ADS)

While gaps in trace-gas fluxes measured via eddy-covariance occur for a variety of reasons, many occur at night due to a stratified (stable) atmosphere close to the surface. Currently, the community standard for eliminating data during periods of stability is to apply a threshold of friction velocity (u*). Despite applying the u* threshold, data often indicate net CO2 uptake at night, casting doubt on whether a u* threshold is accurately eliminating data from stable periods. If, in fact, the u* correction does not eliminate data appropriately, this will influence net annual carbon budgets in two important ways. First, inaccurate nighttime respiration data may remain after post-processing and bias net annual sums toward a stronger sink of CO2. Secondly, if data gaps (created by imposing a u* threshold) are filled by applying empirically derived temperature-moisture response functions based on remaining data, the gap-filled or "corrected" data are then influenced by the possible inaccuracy of the respiration data taken under high u*. Because most flux sites are only equipped with one set of instruments (usually just above the canopy), vertical profiles of turbulent transfer within and above the canopy are generally not available providing few alternatives to the u* correction method to the greater FLUXNET community. The ability to better quantify atmospheric stability within and above the canopy would improve data quality assessment. We test this theory by modeling vertical profiles of turbulent kinetic energy (TKE) using the Advanced Canopy-Atmosphere-Soil Algorithm (ACASA) and comparing it to high frequency TKE data collected by deploying an upward-facing LiDAR (measurements up to 200m) at two AmeriFlux towers: Wind River in Washington and Tonzi in California. LiDar data were collected during a 2-week long spring campaign at each site as well as during a late-summer and fall campaign at Tonzi. Here we show the effect of assessing canopy stability (and thus flux quality) via thresholds based on u* (from eddy-covariance) versus vertical profiles of TKE (from ACASA and LiDAR). Additionally, we validate the model by comparing output to measurements of soil respiration (via the chamber method) and vertical profiles of temperature and wind velocity (via radiosonde measurements). Finally, we compare modeled nighttime fluxes of CO2 to measured fluxes of CO2 during periods when the atmosphere is well-mixed based on the new TKE threshold. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Osuna, J. L.; Wharton, S.; Falk, M.; Paw U, K.; Baldocchi, D. D.; Bible, K.

2012-12-01

172

Attenuation compensation for optical coherence tomography imaging  

NASA Astrophysics Data System (ADS)

Optical coherence tomography (OCT) is a noninvasive technique that provides micrometer-scale imaging of tissue. As most biological tissues are considered turbid, it causes attenuation of the OCT signal and limits the depth penetration. Although a few algorithms had been developed to compensate the attenuation, almost all of them need to extract the scattering parameters before doing the compensation procedure. Because the real biological samples are anisotropic and multilayer-like structure, it is not time-efficient to model and solve these scattering parameters. This paper introduces a new method to compensate the OCT signal attenuation in depth. By analyzing the input signal, a compensation function is adaptively derived for each A-scan line, which can be used effectively to compensate the energy loss in the large sections and enhance the details in the deep, dark-like areas. Three bio-samples, a piece of onion, a Poecilia Wingei fish and a piece of rabbit abdominal aorta, were used to test our method. OCT images obtained by a swept-source OCT system were processed by the proposed method. Results show the visualization of structures in OCT images has been evidently improved, especially in deep region.

Chang, Shoude; Flueraru, Costel; Mao, Youxin; Sherif, Sherif

2009-12-01

173

Compensation for transducer effects in optoacoustic tomography  

NASA Astrophysics Data System (ADS)

Optoacoustic Tomography (OAT) is a hybrid imaging modality that combines the advantages of both optical imaging and ultrasound imaging techniques. Most existing reconstruction algorithms for OAT assume pointlike transducers, which may result in conspicous image blurring and distortions in certain applications. In this work, a new imaging model that incorporates the transducer response is employed for image reconstruction. Computer-simulation studies demonstrate that the new reconstruction method can effectively compensate for image resolution degradation associated with the transducer response.

Wang, Kun; Anastasio, Mark A.; Ermilov, Sergey A.; Brecht, Hans-Peter; Su, Richard; Oraevsky, Alexander A.

2010-02-01

174

Accelerometer-based position reconstruction for the feedforward compensation of fast telescope vibrations in the E-ELT/MICADO  

NASA Astrophysics Data System (ADS)

The amount of image motion caused by vibrations of the telescope structure increases with the size of the telescope. Compensating the effects of structural vibrations in the optical path will be a major design question for adaptive optics (AO) systems in future extremely large telescopes like the E-ELT. A promising control system architecture is the recently developed Dual-Loop-Approach, with a feedforward loop based on accelerometer measurements, compensating for the vibrations in addition to the classical AO feedback loop compensating for atmospheric turbulences. We present our efforts to develop sophisticated estimation and control algorithms for this feedforward loop. The major task from a control engineering point of view is reconstructing the position of the vibrating elements from accelerometer measurements highly deteriorated by low-frequency drift and highfrequency noise. The algorithms are evaluated and compared using a realistic Tip-Tilt-Vibration laboratory test setup. Position reconstruction for a realistic 8 Hz structural resonance with an error of only 4% is achieved. Our ultimate goal is to achieve longer and more sensitive wavefront sensor (WFS) integrations by permitting a smaller bandwidth of the AO feedback loop in the E-ELT/MICADO.

Keck, Alexander; Pott, Jrg-Uwe; Sawodny, Oliver

2014-07-01

175

Thermal compensating mount  

NASA Technical Reports Server (NTRS)

The main objective is to provide a device for maintaining the alignment integrity of an alignment sensitive component over a wide range of temperatures. A thermal compensating mount is presented. A cylindrical extension is integrally formed to the alignment sensitive component. Both the extension and component share the same coefficient of thermal expansion. The cylindrical extension is placed into a mounting structure which has a diameter greater than that of the extension. An adhesive secures the cylindrical extension to the mount. The difference between the diameters of the cylindrical extension and the cylindrical receptacle is such that the differential thermal expansion across the extension and the receptacle edges is exactly compensated for by the thermal compensation of the adhesive between them. Accordingly, the alignment sensitive component does not change position when subjected to temperature variations. One application of this invention is laser optical-path folding prisms, which are fixed to the mounting surface by a small amount of epoxy adhesive.

Jalink, Antony, Jr. (inventor); Campbell, Scott R. (inventor)

1990-01-01

176

Design of the optical fibers for differential mode delay compensation  

NASA Astrophysics Data System (ADS)

We introduce a method for differential mode delay (DMD) compensation by using a special silica GeO2-doped graded-index multimode optical fiber, which provides a reverse reproducing of mode group velocity diagram of the target fiber, and algorithm for design it. Results of proposed method approbation for synthesis of DMD compensation fiber for OM2+/OM3 category target multimode fiber under both central and overfilled launch conditions are represented.

Burdin, Vladimir A.; Bourdine, Anton V.; Delmukhametov, Oleg R.

2012-01-01

177

Robust beam compensation for laser-based additive manufacturing  

Microsoft Academic Search

Todays software for laser-based additive manufacturing compensates for the finite dimensions of the laser spot by insetting the contours of a solid part. However, features having smaller dimensions are removed by this operation, which may significantly alter the structure of thin-walled parts. To avoid potential production errors, this work describes in detail an algorithmic framework that makes beam compensation more

Maarten Moesen; Tom Craeghs; Jean-Pierre Kruth; Jan Schrooten

2011-01-01

178

On adaptive friction compensation  

Microsoft Academic Search

A method of compensating for friction in control systems is presented. The method entails the use of an observer to estimate the friction which is modeled as a constant times the sign of the velocity. The purpose of the observer is to estimate this constant. The observer model is selected to ensure that the error in estimation of the friction

Bernard Friedland; Young-Jin Park

1992-01-01

179

Hybridization of hyperspectral imaging target detection algorithm chains  

NASA Astrophysics Data System (ADS)

Detection of a known target in an image can be accomplished using several different approaches. The complexity and number of steps involved in the target detection process makes a comparison of the different possible algorithm chains desirable. Of the different steps involved, some have a more significant impact than others on the final result-the ability to find a target in an image. These more important steps often include atmospheric compensation, noise and dimensionality reduction, background characterization, and detection (matched filtering for this research). A brief overview of the algorithms to be compared for each step will be presented. This research seeks to identify the most effective set of algorithms for a particular image or target type. Several different algorithms for each step will be presented, to include ELM, FLAASH, MNF, PPI, MAXD, the structured background matched filters OSP, and ASD. The chains generated by these algorithms will be compared using the Forest Radiance I HYDICE data set. Finally, receiver operating characteristic (ROC) curves will be calculated for each algorithm chain and, as an end result, a comparison of the various algorithm chains will be presented.

Grimm, David C.; Messinger, David W.; Kerekes, John P.; Schott, John R.

2005-06-01

180

Motion-compensated highly scalable video compression using an adaptive 3D wavelet transform based on lifting  

Microsoft Academic Search

This paper proposes a new framework for the construction of motion compensated wavelet transforms, with application to efficient highly scalable video compression. Motion compensated transform techniques, as distinct from motion compensated predictive coding, represent a key tool in the development of highly scalable video compression algorithms. The proposed framework overcomes a variety of limitations exhibited by existing approaches. This new

Andrew Secker; David Taubman

2001-01-01

181

Executive Compensation, Incentives, and Risk  

E-print Network

This paper analyzes the link between equity-based compensation and created incentives by (1) deriving a measure of incentives suitable for both linear and non-linear compensation contracts, (2) analyzing the effect of risk ...

Jenter, Dirk

2004-05-28

182

Executive Compensation, Incentives, and Risk  

E-print Network

This paper analyzes the link between equity-based compensation and created incentives by (1) deriving a measure of incentives suitable for both linear and non-linear compensation contracts, (2) analyzing ...

Jenter, Dirk

2004-12-10

183

Regulatory constraints on executive compensation  

E-print Network

This paper explores the influence of economic regulation on the level and structure of executive compensation. We find substantial and persistent differences in CEO compensation between firms subject to economic regulation ...

Joskow, Paul L.

1993-01-01

184

Deferred Compensation Becomes More Common  

ERIC Educational Resources Information Center

A key part of the compensation package for some college and university presidents is money that they do not receive in their paychecks. Formally known as deferred compensation, such payments can take many forms, including supplemental retirement pay, severance pay, or even bonuses. With large institutions leading the way, deferred compensation has

June, Audrey Williams

2006-01-01

185

Bobcat 2013: a hyperspectral data collection supporting the development and evaluation of spatial-spectral algorithms  

NASA Astrophysics Data System (ADS)

The amount of hyperspectral imagery (HSI) data currently available is relatively small compared to other imaging modalities, and what is suitable for developing, testing, and evaluating spatial-spectral algorithms is virtually nonexistent. In this work, a significant amount of coincident airborne hyperspectral and high spatial resolution panchromatic imagery that supports the advancement of spatial-spectral feature extraction algorithms was collected to address this need. The imagery was collected in April 2013 for Ohio University by the Civil Air Patrol, with their Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance (ARCHER) sensor. The target materials, shapes, and movements throughout the collection area were chosen such that evaluation of change detection algorithms, atmospheric compensation techniques, image fusion methods, and material detection and identification algorithms is possible. This paper describes the collection plan, data acquisition, and initial analysis of the collected imagery.

Kaufman, Jason; Celenk, Mehmet; White, A. K.; Stocker, Alan D.

2014-06-01

186

2007 CEO Compensation Study  

NSDL National Science Digital Library

Charity Navigator provides high-quality information about charities in order "to advance a more efficient and responsive philanthropic marketplace." One of the more recently published studies is the 2007 CEO Compensation Study. Visitors can read this annotated report here in its entirety, and it contains a wealth of information about the subject. In the year 2007, their research shows that the top leaders of the 5242 largest charities in America earn an average salary of $145,270. While this amount may strike some as rather large, the report also notes that CEO compensation accounts for just 3.37% of the average organization's spending. The report contains a number of helpful charts, such as those that list average CEO salary by geographic region and by size of charity.

2007-08-01

187

Altitude compensating nozzle evaluation  

NASA Astrophysics Data System (ADS)

Results are presented from a proof-of-concept evaluation of a passively ventilated altitude-compensating nozzle concept, using both perforated nozzle-wall and translating nozzle skirt schemes. Attention is given to the test apparatus. It is established that, with adequate ventilation area, perforated nozzle performance is similar to that of the truncated nozzle, and can be adequately calculated with conventional techniques if 2D kinetics and boundary-layer effects are accounted for.

Parsley, R. C.; van Stelle, K. J.

1992-07-01

188

Chapter 38 Executive compensation  

Microsoft Academic Search

This chapter summarizes the empirical and theoretical research on executive compensation and provides a comprehensive and up-to-date description of pay practices (and trends in pay practices) for chief executive officers (CEOs). Topics discussed include the level and structure of CEO pay (including detailed analyses of annual bonus plans, executive stock options, and option valuation), international pay differences, the pay-setting process,

Kevin J. Murphy

1999-01-01

189

Compensation of significant parametric uncertainties using sliding mode online learning  

NASA Astrophysics Data System (ADS)

An augmented nonlinear inverse dynamics (NID) flight control strategy using sliding mode online learning for a small unmanned aircraft system (UAS) is presented. Because parameter identification for this class of aircraft often is not valid throughout the complete flight envelope, aerodynamic parameters used for model based control strategies may show significant deviations. For the concept of feedback linearization this leads to inversion errors that in combination with the distinctive susceptibility of small UAS towards atmospheric turbulence pose a demanding control task for these systems. In this work an adaptive flight control strategy using feedforward neural networks for counteracting such nonlinear effects is augmented with the concept of sliding mode control (SMC). SMC-learning is derived from variable structure theory. It considers a neural network and its training as a control problem. It is shown that by the dynamic calculation of the learning rates, stability can be guaranteed and thus increase the robustness against external disturbances and system failures. With the resulting higher speed of convergence a wide range of simultaneously occurring disturbances can be compensated. The SMC-based flight controller is tested and compared to the standard gradient descent (GD) backpropagation algorithm under the influence of significant model uncertainties and system failures.

Schnetter, Philipp; Kruger, Thomas

190

Irradiance compensation control for high-energy laser propagation  

SciTech Connect

The quality of propagated Laser light strongly depends on the degree of phase uniformity across the beam at its source. When propagating through turbulent atmosphere, a Strehl ratio of nearly 0.9 is possible if phase correction is made at all spatial scales greater than approximately r{sub o}, the Fried atmospheric cell size. Therefore r{sub o} is a reasonable choice for actuator spacing on the phase compensating adaptive optics. However, analysis of high energy laser propagation has shown that a control law designed to compensate only for atomspheric index fluctuations will drive thermal blooming instabilities. Small initial perturbations in beam irradiance will grow exponentially until the beam breaks up. Therefore it is necessary also to compensate for irradiance perturbations at the same spatial scale as the compensation for phase. Combined phase and irradiance compensation of an HEL has been shown to be stable in theory. Irradiance control can be accomplished with a pair of deformable mirrors spaced apart over a propagation path. Laser light reflected off of the first deformable mirror surface at z = 0 will result in magnitude perturbations some distance away at z = L. The second deformable mirror then recollimates the light. The purpose of simulating the irradiance compensation system is to test the baseline design in such a way that the effect of discrete actuator/sensors and beam edge effects is taken into account in a more realistic manner than can be performed by a 2-D fourier analysis. 7 refs., 9 figs.

Gavel, D.T.

1991-04-18

191

Two block-based motion compensation methods for video coding  

Microsoft Academic Search

Two new motion compensation methods for video coding are presented. The first method named motion-partitioned adaptive block matching algorithm (MPA-BMA) uses motion boundary information as the sub-dividing or merging criteria to form variable-size matching blocks. The second method named predictive block matching algorithm (PBMA) eliminates the need of sending motion data by predicting motion vectors from previously transmitted pixels. The

Yan Huang; Xinhua Zhuang; Changsheng Yang

1996-01-01

192

ISAR imaging compensation of high speed targets based on integrated cubic phase function  

NASA Astrophysics Data System (ADS)

High speed movement of target leads to quadratic phase of the dechirped signal. A new high speed movement compensation method based on integrated cubic phase function is proposed. Numerical result shows that the algorithm can precisely estimate the quadratic phase coefficient and compensate the high resolution range profile under low signal to noise ratio. After compensation, the aberration of range profile is revised and the quality of ISAR image is greatly improved. In this way, the effectiveness of the method is verified.

Tian, Biao; Chen, Zengping; Xu, Shiyou; Liu, Yang

2013-10-01

193

Complexity-reduced digital nonlinear compensation for coherent optical system  

NASA Astrophysics Data System (ADS)

The high complexity of conventional intra-channel nonlinearity compensation algorithms, such as back-propagation, is considered as the major obstacle for the implementation. To reduce the complexity, perturbation analysis is applied because it considers multi-span transmission as one stage. In those perturbation based algorithms, such as perturbation back-propagation (PBP) and perturbation pre-distortion, the number of required compensation stage is much less than that of conventional back-propagation. To reduce the complexity further, the multi-tap finite impulse response filter (FIR) in PBP is replaced with one-tap infinite impulse response (IIR) filter. The number of required compensation stage of IIR PBP is only 15% of conventional back-propagation, whereas the complexity of each stage is almost same. In perturbation pre-distortion, the proposed perturbation combination reduces the number of terms from 19732 to 41, whereas no performance degradation is observed.

Tao, Zhenning; Dou, Liang; Yan, Weizhen; Fan, Yangyang; Li, Lei; Oda, Shoichiro; Akiyama, Yuichi; Nakashima, Hisao; Hoshida, Takeshi; Rasmussen, Jens C.

2013-01-01

194

Path Following with Slip Compensation for a Mars Rover  

NASA Technical Reports Server (NTRS)

A software system for autonomous operation of a Mars rover is composed of several key algorithms that enable the rover to accurately follow a designated path, compensate for slippage of its wheels on terrain, and reach intended goals. The techniques implemented by the algorithms are visual odometry, full vehicle kinematics, a Kalman filter, and path following with slip compensation. The visual-odometry algorithm tracks distinctive scene features in stereo imagery to estimate rover motion between successively acquired stereo image pairs, by use of a maximum-likelihood motion-estimation algorithm. The full-vehicle kinematics algorithm estimates motion, with a no-slip assumption, from measured wheel rates, steering angles, and angles of rockers and bogies in the rover suspension system. The Kalman filter merges data from an inertial measurement unit (IMU) and the visual-odometry algorithm. The merged estimate is then compared to the kinematic estimate to determine whether and how much slippage has occurred. The kinematic estimate is used to complement the Kalman-filter estimate if no statistically significant slippage has occurred. If slippage has occurred, then a slip vector is calculated by subtracting the current Kalman filter estimate from the kinematic estimate. This slip vector is then used, in conjunction with the inverse kinematics, to determine the wheel velocities and steering angles needed to compensate for slip and follow the desired path.

Helmick, Daniel; Cheng, Yang; Clouse, Daniel; Matthies, Larry; Roumeliotis, Stergios

2005-01-01

195

Altitude compensating nozzle evaluation  

NASA Astrophysics Data System (ADS)

Typically, the nozzle area ratio selected for booster applications is a compromise between optimum performance at lift off and optimum performance at altitude. If nozzle area ratio could be tailored for different altitudes, without significant weight increase, vehicle payload performance can be enhanced. This is particularly true for single-stage-to-orbit (SSTO) applications where the nozzle must operate both at sea level and in space. For conventional bell nozzles, altitude compensation is accomplished most effectively by varying the exit areas of the nozzle during ascent. There are two fundamental approaches to varying nozzle exit area. The first is to physically retract the aft skirt of the nozzle allowing operation at the truncated exit area; the skirt is then deployed to allow full nozzle expansion at altitude. The second approach is to design a fixed geometry nozzle to the full and final area ratio and to induce controlled and stable separation at reduced 'effective' exit areas inside the nozzle. This separation is controlled by allowing passive inflow of ambient air. As altitude increases the vent will be closed to prevent outflow of combustion products and to support expansion to a larger effective exit area. This paper summarizes the proof-of-concept evaluation and testing of a passively ventilated altitude compensating nozzle (ACN) concept. The scheme was tested on a modified RL10 under Air Force contract F04611-87-C-0069 in August 1990. This data complements an earlier Air Force ACN activity completed in the early 1970's, under Air Force contract F04611-68-C-0002. In this program the XLR-129 demonstrated significant altitude compensation performance for a two-position translating skirt.

Parsley, R. C.; Vanstelle, Kenneth J.

1992-02-01

196

Self-compensating tensiometer and method  

DOEpatents

A pressure self-compensating tensiometer and method to in situ determine below grade soil moisture potential of earthen soil independent of changes in the volume of water contained within the tensiometer chamber, comprising a body having first and second ends, a porous material defining the first body end, a liquid within the body, a transducer housing submerged in the liquid such that a transducer sensor within the housing is kept below the working fluid level in the tensiometer and in fluid contact with the liquid and the ambient atmosphere.

Hubbell, Joel M. (Idaho Falls, ID); Sisson, James B. (Idaho Falls, ID)

2003-01-01

197

Migration Through Resolution Cell Compensation in ISAR Imaging  

Microsoft Academic Search

Range-Doppler (RD) processing is widely used in conventional inverse synthetic aperture radar (ISAR) imaging. The unwanted translational motion of moving targets is compensated by envelope alignment and autofocus. For existing ISAR imaging algorithms, the scatterers' migration through resolution cells (MTRC) caused by the rotational motion is usually ignored. With the improvement of resolution or the increase of target size, MTRC

Mengdao Xing; Renbiao Wu; Jinqiao Lan; Zheng Bao

2004-01-01

198

Using Weighting Adjustments to Compensate for Survey Nonresponse  

ERIC Educational Resources Information Center

Weighting adjustments are used in some studies to compensate for biased estimators produced by survey nonresponse. Using data from the 2004 National Survey of Student Engagement (NSSE) and the NSSE poststratification weighting algorithm, this study found that weighting adjustments were needed for some, but not all institutions. Unfortunately, no

Pike, Gary R.

2008-01-01

199

Failure and Redemption of Multifilter Rotating Shadowband Radiometer (MFRSR)/Normal Incidence Multifilter Radiometer (NIMFR) Cloud Screening: Contrasting Algorithm Performance at Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) and Southern Great Plains (SGP) Sites  

SciTech Connect

Well-known cloud-screening algorithms, which are designed to remove cloud-contaminated aerosol optical depths (AOD) from AOD measurements, have shown great performance at many middle-to-low latitude sites around the world. However, they may occasionally fail under challenging observational conditions, such as when the sun is low (near the horizon) or when optically thin clouds with small spatial inhomogeneity occur. Such conditions have been observed quite frequently at the high-latitude Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) sites. A slightly modified cloud-screening version of the standard algorithm is proposed here with a focus on the ARM-supported Multifilter Rotating Shadowband Radiometer (MFRSR) and Normal Incidence Multifilter Radiometer (NIMFR) data. The modified version uses approximately the same techniques as the standard algorithm, but it additionally examines the magnitude of the slant-path line of sight transmittance and eliminates points when the observed magnitude is below a specified threshold. Substantial improvement of the multi-year (1999-2012) aerosol product (AOD and its Angstrom exponent) is shown for the NSA sites when the modified version is applied. Moreover, this version reproduces the AOD product at the ARM Southern Great Plains (SGP) site, which was originally generated by the standard cloud-screening algorithms. The proposed minor modification is easy to implement and its application to existing and future cloud-screening algorithms can be particularly beneficial for challenging observational conditions.

Kassianov, Evgueni I.; Flynn, Connor J.; Koontz, Annette S.; Sivaraman, Chitra; Barnard, James C.

2013-09-11

200

An Adaptive Compensation of Moving Clutter Doppler Shift for Helicopter MTD Radar  

Microsoft Academic Search

The accurate estimation and compensation of the moving clutter Doppler shift are essentials for the moving target detection of the airborne radar system. In this paper, a technique for the real-time estimation and compensation of the moving clutter Doppler shift due to the moving radar platform is presented for the airborne pulsed Doppler radar system. A new algorithm employs the

Young-Kil Kwag; Min-Su Choi; Chul-Ho Jung

2006-01-01

201

Low-complexity pilot-aided compensation for carrier frequency offset and I\\/Q imbalance  

Microsoft Academic Search

We propose a novel pilot-aided compensation scheme for carrier frequency offset (CFO) and I\\/Q imbalance. The proposed scheme comprises a generalized periodic pilot and a low-complexity acquisition algorithm, where the CFO and the coefficients for I\\/Q imbalance compensation can be obtained in explicit closed-form.

Hai Lin; Xu Zhu; Katsumi Yamashita

2010-01-01

202

Anisoplanatism in Adaptive Optics Compensation of a Focused Beam Using Distributed Beacons  

Microsoft Academic Search

In systems that achieve laser beam propagation through atmospheric turbulence by phase compensation with adaptive optics, the performance depends on the beacon's spatial distribution. A formulation is obtained to calculate the anisoplanatic Strehl ratio of a phase compensated, focused beam for any beacon distribution and turbulence profile. Analytic results are obtained for several beacon geometries corresponding to practical systems, in

Phillip D. Stroud

1996-01-01

203

28 CFR 79.3 - Compensable claim categories under the Act.  

Code of Federal Regulations, 2010 CFR

...every criterion of eligibility for at least one of the following compensable categories designated in the Act: (1) Claims of leukemia. (i) For persons exposed to fallout from the atmospheric detonation of nuclear devices at the Nevada Test Site due...

2010-07-01

204

Laser Gyro Temperature Compensation Using Modified RBFNN  

PubMed Central

To overcome the effect of temperature on laser gyro zero bias and to stabilize the laser gyro output, this study proposes a modified radial basis function neural network (RBFNN) based on a Kohonen network and an orthogonal least squares (OLS) algorithm. The modified method, which combines the pattern classification capability of the Kohonen network and the optimal choice capacity of OLS, avoids the random selection of RBFNN centers and improves the compensation accuracy of the RBFNN. It can quickly and accurately identify the effect of temperature on laser gyro zero bias. A number of comparable identification and compensation tests on a variety of temperature-changing situations are completed using the multiple linear regression (MLR), RBFNN and modified RBFNN methods. The test results based on several sets of gyro output in constant and changing temperature conditions demonstrate that the proposed method is able to overcome the effect of randomly selected RBFNN centers. The running time of the method is about 60 s shorter than that of traditional RBFNN under the same test conditions, which suggests that the calculations are reduced. Meanwhile, the compensated gyro output accuracy using the modified method is about 7.0 10?4 /h; comparatively, the traditional RBFNN is about 9.0 10?4 /h and the MLR is about 1.4 10?3 /h. PMID:25302814

Ding, Jicheng; Zhang, Jian; Huang, Weiquan; Chen, Shuai

2014-01-01

205

An Examination Of Altitude Compensation Through Idealised Nozzles and Trajectories  

NASA Astrophysics Data System (ADS)

This paper presents an analysis of the impact of applying altitude compensating nozzles to two representative vehicles. The first is the Space Shuttle, typical of modern high performance systems that operate a single propulsive unit from sea level to vacuum, and the second is Reaction Engines Limited Skylon spaceplane, representative of advanced single stage to orbit concepts. A general investigation of advanced nozzle concepts is provided by one dimensional analysis, using ideal and non- ideal compensating, and non-compensating nozzles. The effect of imperfect compensation (resulting in lower effective exit pressures than ambient) on altitude compensating nozzles is analysed, as is the removal of the restriction on maximum area ratio, made possible by these devices. A simplified trajectory analysis is used to reduce the complexity of the process and maintain generality. Although the use of a fixed trajectory for all nozzles means that some fidelity to the real world is lost, particularly as the area ratio or compensation efficiency is increased, the results qualitatively demonstrate that the impact of compensation efficiency is relatively small compared to that of the removal of the limitation on area ratio. This is particularly true for Shuttle type trajectories, where the vehicle leaves the atmosphere as rapidly as possible. The increase in payload estimated by the current analysis is significant, in some cases being over 25%. Although practical considerations not included mean that the increase in payload realistically feasible will not be as large as this, even a relatively small fraction of this value still represents an attractive proposition, and demonstrates that compensating nozzles provide a promising route to lowering launch costs per kilogramme. This is particularly the case if, as is implied by these results, the actual compensating pressure is not particularly important.

Taylor, N.

206

Control optimization, stabilization and computer algorithms for aircraft applications  

NASA Technical Reports Server (NTRS)

Research related to reliable aircraft design is summarized. Topics discussed include systems reliability optimization, failure detection algorithms, analysis of nonlinear filters, design of compensators incorporating time delays, digital compensator design, estimation for systems with echoes, low-order compensator design, descent-phase controller for 4-D navigation, infinite dimensional mathematical programming problems and optimal control problems with constraints, robust compensator design, numerical methods for the Lyapunov equations, and perturbation methods in linear filtering and control.

1975-01-01

207

Compensations during Unsteady Locomotion.  

PubMed

Locomotion in a complex environment is often not steady, but the mechanisms used by animals to power and control unsteady locomotion (stability and maneuverability) are not well understood. We use behavioral, morphological, and impulsive perturbations to determine the compensations used during unsteady locomotion. At the level both of the whole-body and of joints, quasi-stiffness models are useful for describing adjustments to the functioning of legs and joints during maneuvers. However, alterations to the mechanics of legs and joints often are distinct for different phases of the step cycle or for specific joints. For example, negotiating steps involves independent changes of leg stiffness during compression and thrust phases of stance. Unsteady locomotion also involves parameters that are not part of the simplest reduced-parameter models of locomotion (e.g., the spring-loaded inverted pendulum) such as moments of the hip joint. Extensive coupling among translational and rotational parameters must be taken into account to stabilize locomotion or maneuver. For example, maneuvers with morphological perturbations (increased rotational inertial turns) involve changes to several aspects of movement, including the initial conditions of rotation and ground-reaction forces. Coupled changes to several parameters may be employed to control maneuvers on a trial-by-trial basis. Compensating for increased rotational inertia of the body during turns is facilitated by the opposing effects of several mechanical and behavioral parameters. However, the specific rules used by animals to control translation and rotation of the body to maintain stability or maneuver have not been fully characterized. We initiated direct-perturbation experiments to investigate the strategies used by humans to maintain stability following center-of-mass (COM) perturbations. When walking, humans showed more resistance to medio-lateral perturbations (lower COM displacement). However, when running, humans could recover from the point of maximum COM displacement faster than when walking. Consequently, the total time necessary for recovery was not significantly different between walking and running. Future experiments will determine the mechanisms used for compensations during unsteady locomotion at the behavioral, joint, and muscle levels. Using reduced-parameter models will allow common experimental and analytical frameworks for the study of both stability and maneuverability and the determination of general control strategies for unsteady locomotion. PMID:24948138

Qiao, Mu; Jindrich, Devin L

2014-12-01

208

Temperature compensated photovoltaic array  

DOEpatents

A temperature compensated photovoltaic module (20) comprised of a series of solar cells (22) having a thermally activated switch (24) connected in parallel with several of the cells (22). The photovoltaic module (20) is adapted to charge conventional batteries having a temperature coefficient (TC) differing from the temperature coefficient (TC) of the module (20). The calibration temperatures of the switches (24) are chosen whereby the colder the ambient temperature for the module (20), the more switches that are on and form a closed circuit to short the associated solar cells (22). By shorting some of the solar cells (22) as the ambient temperature decreases, the battery being charged by the module (20) is not excessively overcharged at lower temperatures. PV module (20) is an integrated solution that is reliable and inexpensive.

Mosher, Dan Michael (Plano, TX)

1997-11-18

209

Borehole compensated KUT log  

SciTech Connect

A method of logging earth formations to ascertain relative elemental abundances of potassium (K), uranium (U) and thorium (T) is disclosed. A natural gamma ray spectrum of an unknown borehole is compared with individual standard gamma ray spectra of potassium, uranium and thorium in at least four energy ranges or bands. Decay peaks of the three elements are encompassed by three of the energy bands and at least one other energy band is used to monitor the changes in shape of the unknown spectrum caused by borehole conditions differing from that of the standard or calibration boreholes. A function derived from the gamma ray count rates in the four bands is used to compensate the elemental abundances of the three elements to be detected in the unknown spectrum for the effects of differing borehole conditions in the unknown borehole from the standard borehole conditions.

Arnold, D.M.; Schultz, W.E.; Smith, H.D. Jr.

1984-03-13

210

Temperature compensated photovoltaic array  

DOEpatents

A temperature compensated photovoltaic module comprises a series of solar cells having a thermally activated switch connected in parallel with several of the cells. The photovoltaic module is adapted to charge conventional batteries having a temperature coefficient differing from the temperature coefficient of the module. The calibration temperatures of the switches are chosen whereby the colder the ambient temperature for the module, the more switches that are on and form a closed circuit to short the associated solar cells. By shorting some of the solar cells as the ambient temperature decreases, the battery being charged by the module is not excessively overcharged at lower temperatures. PV module is an integrated solution that is reliable and inexpensive. 2 figs.

Mosher, D.M.

1997-11-18

211

OCT skin image enhancement through attenuation compensation.  

PubMed

The enhancement of optical coherence tomography (OCT) skin images can help dermatologists investigate the morphologic information of the images more effectively. In this paper, we propose an enhancement algorithm with the stages that includes speckle reduction, skin layer detection, and attenuation compensation. A weighted median filter is designed to reduce the level of speckle while preserving the contrast. A novel skin layer detection technique is then applied to outline the main skin layers: stratum corneum, epidermis, and dermis. The skin layer detection algorithm does not make any assumption about the structure of the skin. A model of the light attenuation is then used to estimate the attenuation coefficient of the stratum corneum, epidermis, and dermis layers. The performance of the algorithm has been evaluated qualitatively based on visual evaluation and quantitatively using two no-reference quality metrics: signal-to-noise ratio and contrast-to-noise ratio. The enhancement algorithm is tested on 35 different skin OCT images, which show significant improvements in the quality of the images, especially in the structures at deeper levels. PMID:22858930

Hojjatoleslami, Ali; Avanaki, Mohammad R N

2012-07-20

212

Alternative Teacher Compensation: A Primer  

ERIC Educational Resources Information Center

This policy primer is designed to provide base-line information about new forms of teacher pay that are emerging around the country, to support the local conversations and negotiations that will lead to the development of innovative compensation systems. It identifies reasons why teacher compensation is high on local, state, and federal policy

Koppich, Julia E.; Rigby, Jessica

2009-01-01

213

How to Treat Compensated Absences.  

ERIC Educational Resources Information Center

Discusses compensated absences such as future vacation, sick leave, and other absences that must be recognized for accounting and financial reporting purposes. Explains Governmental Accounting Standards Board distinctions between governmental and proprietary fund models. School districts and municipalities must now account for compensated

Lewandowski, Raymond J.

1986-01-01

214

Executive Compensation: Excessive or Equitable?  

Microsoft Academic Search

The eighties and nineties have seen much debate about CEO compensation. Critics of CEO compensation support their contention of excessive and inequitable CEO pay based on a number of factors and premises. This paper examines the validity of these arguments. We show why many of these arguments fail to persuade, in part, because they attempt to determine propriety of CEO

Donald Nichols; Chandra Subramaniam

2001-01-01

215

Atmospheric illumination and shadows  

Microsoft Academic Search

The shadow volume algorithm of Frank Crow was reorganized to provide information on the regions of illuminated space in front of each visible surface. This information is used to calculate the extra intensity due to atmospheric scattering, so when the atmosphere is partly in shadow, columns of scattered light will be visible. For efficiency in sorting the shadow edges, the

Nelson L. Max

1986-01-01

216

Remote sensing reflectance in the near infrared derived from SeaWiFS: implications for river plume particle size distribution, atmospheric correction, and bio-optical algorithms  

Microsoft Academic Search

Remote sensing reflectance (Rrs) in the near-infrared (NIR) wavelengths is assumed negligible over open ocean clear waters, a basis for atmospheric correction of remote ocean color sensors such as the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). For turbid river plumes such assumption is no longer valid, and various alternative approaches have been proposed for atmospheric correction. The default option in SeaDAS

Chuanmin Hu

2003-01-01

217

CEO turnover and compensation: An empirical investigation  

Microsoft Academic Search

CEO turnover events provide a unique opportunity for boards of directors to restructure CEO compensation packages. Consequently, changes and\\/or adjustments to CEO compensation packages under such circumstances can prove informative to the ongoing debate regarding CEO compensation. This paper investigates the nature of CEO compensation by exploring what happens to such compensation when a management turnover event takes place. Specifically,

Rachel L Graefe-Anderson

2009-01-01

218

More rain compensation results  

NASA Technical Reports Server (NTRS)

To reduce the impact of rain-induced attenuation in the 20/30 GHz band, the attenuation at a specified signal frequency must be estimated and extrapolated forward in time on the basis of a noisy beacon measurement. Several studies have used model based procedures for solving this problem in statistical inference. Perhaps the most widely used model-based paradigm leads to the Kalman filter and its lineal variants. In this formulation, the dynamic features of the attenuation are represented by a state process (x(sub t)). The observation process (y(sub t)) is derived from beacon measurements. Some ideas relating to the signal processing problems related to uplink power control are presented. It is shown that some easily implemented algorithms hold promise for use in estimating rain induced fades. The algorithms were applied to actual data generated at the Virginia Polytechnic Institute and State University (VPI) test facility. Because only one such event was studied, it is not clear that the algorithms will have the same effectiveness when a wide range of events are studied.

Sworder, D. D.; Vojak, R.

1992-01-01

219

[Vestibular compensation studies]. [Vestibular Compensation and Morphological Studies  

NASA Technical Reports Server (NTRS)

The following topics are reported: neurophysiological studies on MVN neurons during vestibular compensation; effects of spinal cord lesions on VNC neurons during compensation; a closed-loop vestibular compensation model for horizontally canal-related MVN neurons; spatiotemporal convergence in VNC neurons; contributions of irregularly firing vestibular afferents to linear and angular VOR's; application to flight studies; metabolic measures in vestibular neurons; immediate early gene expression following vestibular stimulation; morphological studies on primary afferents, central vestibular pathways, vestibular efferent projection to the vestibular end organs, and three-dimensional morphometry and imaging.

Perachio, Adrian A. (Principal Investigator)

1996-01-01

220

Minireview: Sex Differences in Adult and Developing Brains: Compensation, Compensation, Compensation  

E-print Network

Minireview: Sex Differences in Adult and Developing Brains: Compensation, Compensation, Massachusetts 01003 Despite decades of research, we do not know the functional significance of most sex differences in the brain. We are heavily invested in the idea that sex differences in brain struc- ture cause

de Vries, Geert J.

221

Compensated pulsed alternator  

DOEpatents

This invention relates to an electromechanical energy converter with inertial energy storage. The device, a single phase, two or multi-pole alternator with stationary field coils, and a rotating armature is provided. The rotor itself may be of laminated steel for slower pulses or for faster pulses should be nonmagnetic and electrically nonconductive in order to allow rapid penetration of the field as the armature coil rotates. The armature coil comprises a plurality of power generating conductors mounted on the rotor. The alternator may also include a stationary or counterrotating compensating coil to increase the output voltage thereof and to reduce the internal impedance of the alternator at the moment of peak outout. As the machine voltage rises sinusoidally, an external trigger switch is adapted to be closed at the appropriate time to create the desired output current from said alternator to an external load circuit, and as the output current passes through zero a self-commutating effect is provided to allow the switch to disconnect the generator from the external circuit.

Weldon, William F. (Austin, TX); Driga, Mircea D. (Austin, TX); Woodson, Herbert H. (Austin, TX)

1980-01-01

222

Human Resource Management: Employee Compensation Guide  

E-print Network

Employee compensation is important to successful employee recruitment, retention, motivation, performance, feedback and satisfaction. This publication explains the many alternatives employers have for creating compensation packages....

Fogleman, Sarah L.; McCorkle, Dean

2009-04-08

223

Genetic model compensation: Theory and applications  

NASA Astrophysics Data System (ADS)

The adaptive filtering algorithm known as Genetic Model Compensation (GMC) was originally presented in the author's Master's Thesis. The current work extends this earlier work. GMC uses a genetic algorithm to optimize filter process noise parameters in parallel with the estimation of the state and based only on the observational information available to the filter. The original stochastic state model underlying GMC was inherited from the antecedent, non-adaptive Dynamic Model Compensation (DMC) algorithm. The current work develops the stochastic state model from a linear system viewpoint, avoiding the simplifications and approximations of the earlier development, and establishes Riemann sums as unbiased estimators of the stochastic integrals which describe the evolution of the random state components. These are significant developments which provide GMC with a solid theoretical foundation. Orbit determination is the area of application in this work, and two types of problems are studied: real-time autonomous filtering using absolute GPS measurements and precise post-processed filtering using differential GPS measurements. The first type is studied in a satellite navigation simulation in which pseudorange and pseudorange rate measurements are processed by an Extended Kalman Filter which incorporates both DMC and GMC. Both estimators are initialized by a geometric point solution algorithm. Using measurements corrupted by simulated Selective Availability errors, GMC reduces mean RSS position error by 6.4 percent, reduces mean clock bias error by 46 percent, and displays a marked improvement in covariance consistency relative to DMC. To study the second type of problem, GMC is integrated with NASA Jet Propulsion Laboratory's Gipsy/Oasis-II (GOA-II) precision orbit determination program creating an adaptive version of GOA-II's Reduced Dynamic Tracking (RDT) process noise formulation. When run as a sequential estimator with GPS measurements from the TOPEX satellite and ground station network, this adaptive version of GOA-II reduces mean RSS position error by 5.9 percent and mean RSS velocity error by 3.7 percent relative to non-adaptive RDT. The success of this integration effort establishes GMC as a viable and widely applicable adaptive filtering algorithm. Standard hypothesis testing techniques are used in both studies to establish the statistical significance of GMC's apparent superiority over conventional non-adaptive process noise formulations.

Cruickshank, David Raymond

224

Operational Atmospheric Correction of Landsat TM Data  

Microsoft Academic Search

The recent algorithms developed for biophysical variables assessment require accurate surface reflectance measurements. This article describes algorithms used for atmospheric correction of Landsat Thematic Mapper (TM) data. Atmospheric corrections include Rayleigh scattering, gaseous absorption, and aerosol scattering in three visible channels (480 nm, 560 nm, and 660 nm), and the near-infrared channel (830 nm). Atmospheric constituents such as water vapor

Hassan Ouaidrari; Eric F. Vermote

1999-01-01

225

Altitude Compensating Nozzle Concepts Evaluation.  

National Technical Information Service (NTIS)

This report contains the summary of work accomplished during summer of 2000 by Mr. Chad Hammons, undergraduate senior student, Mississippi State University/ERC in support of NASA/MSFC mission pertinent to Altitude compensating nozzle concepts evaluations....

B. Soni

2000-01-01

226

Robotic compensation of cerebellar ataxia  

E-print Network

The cerebellum is believed to play a role in dynamic compensation in the human motor control system. When it is damaged, subjects make clumsy movements with reduced acceleration, increased overshoot, and swerving in ...

Smith, Eric D., S.M. Massachusetts Institute of Technology

2007-01-01

227

Perks and Culture Competitive compensation  

E-print Network

Perks and Culture · Competitive compensation · Health coverage · Wellness program · Relocation events and social gatherings · Unlimited free coffee drinks! Examples of Interesting Projects · Cloud

Julien, Christine

228

National Compensation Survey Home Page  

NSDL National Science Digital Library

The Bureau of Labor Statistics (BLS) posts this publication online, with sections downloadable as .pdf files. The release, the National Compensation Survey, is a redesign of BLS' compensation statistics to reflect the workplace of the 21st century. From the main page, users can access the full .pdf-format text of the survey results as well as a summary, and a wealth of other related sites and documents.

229

Economics of static VAR compensation  

SciTech Connect

This project was initiated in anticipation of widened use of static VAR (volt-ampere-reactive) compensation on US bulk-power transmission systems to increase levels of secure power transfer. Project objectives were to deten-nine power system cost savings and reliability benefits resulting from such use. System operating cost and stability probabilities were compared with and without static VAR compensation, applying simulation techniques. For the particular system model studied, there was a 21.4 percent reduction in operating costs taking into account losses added by the static VAR compensator. A procedure was developed to compare instability probabilities for various loadings and static VAR compensator sizes on a power system. For the particular system model studied, the static VAR compensator provided a significant increase in stability but over a narrow range of loading. Static VAR compensation is one of a number of promising FACTS (Flexible AC Transmission System) technologies for handling the demands of increased power transfers on power systems where transmission lines cannot be built or as a short-term altemative to building additional lines.

Alvarado, F.L.; DeMarco, C.; Jung, T.H. (Wisconsin Univ., Madison, WI (United States). Dept. of Electrical and Computer Engineering)

1992-09-01

230

Clouds and the Earth's Radiant Energy System (CERES) algorithm theoretical basis document. volume 4; Determination of surface and atmosphere fluxes and temporally and spatially averaged products (subsystems 5-12); Determination of surface and atmosphere fluxes and temporally and spatially averaged products  

NASA Technical Reports Server (NTRS)

The theoretical bases for the Release 1 algorithms that will be used to process satellite data for investigation of the Clouds and the Earth's Radiant Energy System (CERES) are described. The architecture for software implementation of the methodologies is outlined. Volume 4 details the advanced CERES techniques for computing surface and atmospheric radiative fluxes (using the coincident CERES cloud property and top-of-the-atmosphere (TOA) flux products) and for averaging the cloud properties and TOA, atmospheric, and surface radiative fluxes over various temporal and spatial scales. CERES attempts to match the observed TOA fluxes with radiative transfer calculations that use as input the CERES cloud products and NOAA National Meteorological Center analyses of temperature and humidity. Slight adjustments in the cloud products are made to obtain agreement of the calculated and observed TOA fluxes. The computed products include shortwave and longwave fluxes from the surface to the TOA. The CERES instantaneous products are averaged on a 1.25-deg latitude-longitude grid, then interpolated to produce global, synoptic maps to TOA fluxes and cloud properties by using 3-hourly, normalized radiances from geostationary meteorological satellites. Surface and atmospheric fluxes are computed by using these interpolated quantities. Clear-sky and total fluxes and cloud properties are then averaged over various scales.

Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator); Baum, Bryan A.; Charlock, Thomas P.; Green, Richard N.; Lee, Robert B., III; Minnis, Patrick; Smith, G. Louis; Coakley, J. A.; Randall, David R.

1995-01-01

231

GIFTS SM EDU Level 1B Algorithms  

NASA Technical Reports Server (NTRS)

The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) SensorModule (SM) Engineering Demonstration Unit (EDU) is a high resolution spectral imager designed to measure infrared (IR) radiances using a Fourier transform spectrometer (FTS). The GIFTS instrument employs three focal plane arrays (FPAs), which gather measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The raw interferogram measurements are radiometrically and spectrally calibrated to produce radiance spectra, which are further processed to obtain atmospheric profiles via retrieval algorithms. This paper describes the GIFTS SM EDU Level 1B algorithms involved in the calibration. The GIFTS Level 1B calibration procedures can be subdivided into four blocks. In the first block, the measured raw interferograms are first corrected for the detector nonlinearity distortion, followed by the complex filtering and decimation procedure. In the second block, a phase correction algorithm is applied to the filtered and decimated complex interferograms. The resulting imaginary part of the spectrum contains only the noise component of the uncorrected spectrum. Additional random noise reduction can be accomplished by applying a spectral smoothing routine to the phase-corrected spectrum. The phase correction and spectral smoothing operations are performed on a set of interferogram scans for both ambient and hot blackbody references. To continue with the calibration, we compute the spectral responsivity based on the previous results, from which, the calibrated ambient blackbody (ABB), hot blackbody (HBB), and scene spectra can be obtained. We now can estimate the noise equivalent spectral radiance (NESR) from the calibrated ABB and HBB spectra. The correction schemes that compensate for the fore-optics offsets and off-axis effects are also implemented. In the third block, we developed an efficient method of generating pixel performance assessments. In addition, a random pixel selection scheme is designed based on the pixel performance evaluation. Finally, in the fourth block, the single pixel algorithms are applied to the entire FPA.

Tian, Jialin; Gazarik, Michael J.; Reisse, Robert A.; Johnson, David G.

2007-01-01

232

GIFTS SM EDU Level 1B algorithms  

NASA Astrophysics Data System (ADS)

The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) Sensor Module (SM) Engineering Demonstration Unit (EDU) is a high resolution spectral imager designed to measure infrared (IR) radiances using a Fourier transform spectrometer (FTS). The GIFTS instrument employs three focal plane arrays (FPAs), which gather measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The raw interferogram measurements are radiometrically and spectrally calibrated to produce radiance spectra, which are further processed to obtain atmospheric profiles via retrieval algorithms. This paper describes the GIFTS SM EDU Level 1B algorithms involved in the calibration. The GIFTS Level 1B calibration procedures can be subdivided into four blocks. In the first block, the measured raw interferograms are first corrected for the detector nonlinearity distortion, followed by the complex filtering and decimation procedure. In the second block, a phase correction algorithm is applied to the filtered and decimated complex interferograms. The resulting imaginary part of the spectrum contains only the noise component of the uncorrected spectrum. Additional random noise reduction can be accomplished by applying a spectral smoothing routine to the phase-corrected spectrum. The phase correction and spectral smoothing operations are performed on a set of interferogram scans for both ambient and hot blackbody references. To continue with the calibration, we compute the spectral responsivity based on the previous results, from which, the calibrated ambient blackbody (ABB), hot blackbody (HBB), and scene spectra can be obtained. We now can estimate the noise equivalent spectral radiance (NESR) from the calibrated ABB and HBB spectra. The correction schemes that compensate for the fore-optics offsets and off-axis effects are also implemented. In the third block, we developed an efficient method of generating pixel performance assessments. In addition, a random pixel selection scheme is designed based on the pixel performance evaluation. Finally, in the fourth block, the single pixel algorithms are applied to the entire FPA.

Tian, Jialin; Gazarik, Michael J.; Reisse, Robert A.; Johnson, David G.

2007-10-01

233

An Alternate Method to Springback Compensation for Sheet Metal Forming  

PubMed Central

The aim of this work is to improve the accuracy of cold stamping product by accommodating springback. This is a numerical approach to improve the accuracy of springback analysis and die compensation process combining the displacement adjustment (DA) method and the spring forward (SF) algorithm. This alternate hybrid method (HM) is conducted by firstly employing DA method followed by the SF method instead of either DA or SF method individually. The springback shape and the target part are used to optimize the die surfaces compensating springback. The hybrid method (HM) algorithm has been coded in Fortran and tested in two- and three-dimensional models. By implementing the HM, the springback error can be decreased and the dimensional deviation falls in the predefined tolerance range. PMID:25165738

Omar, Badrul; Jusoff, Kamaruzaman

2014-01-01

234

Synthesis of birefringent equalizing filters for WDM dispersion compensation  

NASA Astrophysics Data System (ADS)

We present a synthesis algorithm and design example for birefringent equalizing filters, suitable for dispersion compensation in wavelength division multiplexed (WDM) communication systems. A WDM equalizer with dispersion 2003 ps/nm over an operational frequency range of 10 GHz was designed with maximum deviation of the group delay of 3.86 ps. The effects of various factors on the equalizer performance were discussed.

Chu, R. H.; Town, G. E.

2002-12-01

235

A frequency compensated real time DSP GMSK modem  

E-print Network

. 2. The Amplifier 3. A/D Converter and Lowpass Filter of the Spec- trum Signal Processing Daughter Module 4. The DSP Processor THEORY ON GMSK MODULATION AND DEMODULATION A. GMSK Modulation 1. Differential Demodulation . 2. GMSK Demodulation...-time point of view, through a real- time implementation of a Gaussian Minimum Shift Keying (GMSK) signaling system, and a receiver implemented on a Texas Instruments TMS320C40 DSP processor. A large frequency offset compensation algorithm, especially...

Aziz, Ahsan Ul

2012-06-07

236

Atmospheric inversion in the presence of clouds: an adaptive ELM approach  

NASA Astrophysics Data System (ADS)

Many algorithms exist to invert airborne imagery from units of either radiance or sensor specific digital counts to units of reflectance. These compensation algorithms remove unwanted atmospheric variability allowing objects on the ground to be analyzed. Low error levels in homogenous atmospheric conditions have been demonstrated. In many cases however, clouds are present in the atmosphere which introduce error into the inversion at unacceptable levels. For example, the relationship that is defined between sensor reaching radiance and ground reflectance in a cloud free scene will not be the same as in a scene with clouds. A novel method has been developed which utilizes ground based measurements to modify the empirical line method (ELM) approach on a per-pixel basis. A physics based model of the atmosphere is used to generate a spatial correction for the ELM. Creation of this model is accomplished by analyzing whole-sky imagery to produce a cloud mask which drives input parameters to the radiative transfer (RT) code MODTRAN. The RT code is run for several different azimuth and zenith orientations to create a three-dimensional representation of the hemisphere. The model is then used to achieve a per-pixel correction by adjusting the ELM slope spatially. This method is applied to real data acquired over the atmospheric radiation measurement (ARM) site in Lamount, OK. Performance of the method is evaluated with the Hyperspectral Digital Imagery Collection Experiment (HYDICE) instrument as well as a simulated multi-spectral system.

Bartlett, Brent; Schott, John R.

2007-09-01

237

Compensating for pneumatic distortion in pressure sensing devices  

NASA Technical Reports Server (NTRS)

A general numerical technique for obtaining unsteady pressure measurements using conventional pressure sensing technology has been developed. A pneumatic distortion model, based on the Navier-Stokes equations of momentum and continuity, was reduced to a low-order, state-variable model retaining most of the dynamic characteristics of the full model. The reduced-order model is coupled with results from minimum variance estimation theory to develop an algorithm to compensate the effects of pneumatic distortion. Both postflight and real-time algorithms were developed and evaluated using simulated and flight data.

Whitmore, Stephen A.; Leondes, Cornelius T.

1990-01-01

238

Self-compensation in semiconductors  

NASA Astrophysics Data System (ADS)

The problem of self-compensation of charged dopants is analyzed. Special emphasis is given to dopants in binary oxides. It is shown that one can determine the degree of self-compensation from the properties of the host material and dopant concentration alone. It is further shown that for a native p-type semiconductor, donors are compensated, mostly, by native ionic defects. On the other hand, doping with acceptors allows us to increase significantly the hole concentration, i.e., self-compensation is low under high doping levels. For a native n-type semiconductor the opposite is true, namely, extrinsic acceptors are mainly compensated by native ionic defects. It is shown that the changes in concentration of all the charged defects are simply related by a single factor, the doping factor f, or its power fk where k depends solely on the defect's charge. Quantitative calculations of f and defect concentrations are presented for Cu2O, which was used as a model material. It is found that for p-type Cu2O doping with donors results in f within the range of 1-10, depending on the dopant concentration and P(O2). This means that the hole concentration decreases and the electron concentration increases at most by a factor of 10. Therefore one does not expect to obtain a changeover from p- to n-type cuprous oxide by doping, under equilibrium conditions. Most of the donors are compensated by negative ionic defects. Self-compensation in the presence of amphoteric defects and Fermi level stabilization are discussed, using the former formalism.

Tsur, Y.; Riess, I.

1999-09-01

239

Motion-compensated subband coding with scene adaptivity  

NASA Astrophysics Data System (ADS)

This paper presents a new motion compensated subband video coding algorithm with scene adaptive motion interpolation. The work builds on temporal segmentation for determining the reference frame positions, and multi-resolution motion estimation in the subband domain. In the proposed approach, the reference frames for motion estimation are adaptively selected using the temporal segmentation of the lowest spatial subband. Motion compensation is used after subband filtering because it produces better performance than subband filtering after motion compensation. The proposed scene adaptive scheme, temporally adaptive motion interpolation (TAMI), determines the number and the positions of the reference frames for motion estimation using two types of temporal segmentation algorithms. The input video is split into the 7 spatial subbands by using a pair of low-pass and high-pass biorthogonal filters, and the TAMI algorithm is applied on the lowest of the subbands. Motion vectors for each subband are generated by a hierarchical motion estimation approach. Block-wise DPCM and a uniform quantizer are used only for the lowest subband of an intra frame, and all the other subbands are coded by PCM with a dead-zone quantizer. Simulation results show that the scene adaptive scheme compares favorably with the fixed interpolation structure.

Lee, Jungwoo; Dickinson, Bradley W.

1994-05-01

240

Pneumatic distortion compensation for aircraft surface pressure sensing devices  

NASA Technical Reports Server (NTRS)

In this paper a technique of compensating for pneumatic distortion in aircraft surface pressure sensing devices is developed. The compensation allows conventional pressure sensing technology to obtain improved unsteady pressure measurements. Pressure distortion caused by frictional attenuation and pneumatic resonance within the sensing system makes obtaining unsteady pressure measurements by conventional sensors difficult. Typically, most of the distortion occurs within the pneumatic tubing used to transmit pressure impulses from the surface of the aircraft to the measurement transducer. This paper develops a second-order distortion model that accurately describes the behavior of the primary wave harmonic of the pneumatic tubing. The model is expressed in state-variable form and is coupled with standard results from minimum-variance estimation theory to develop an algorithm to compensate for the effects of pneumatic distortion. Both postflight and real-time algorithms are developed and evaluated using simulated and flight data. Covariance selection and filter-tuning examples are presented. Results presented verify that, given appropriate covariance magnitudes, the algorithms accurately reconstruct surface pressure values from remotely sensed pressure measurements.

Whitmore, Stephen A.; Leondes, Cornelius T.

1991-01-01

241

28 CFR 301.301 - Compensable and noncompensable injuries.  

Code of Federal Regulations, 2011 CFR

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.301 Compensable... (a) No compensation for work-related injuries resulting...Compensation may only be paid for work-related injuries or...

2011-07-01

242

28 CFR 301.301 - Compensable and noncompensable injuries.  

Code of Federal Regulations, 2012 CFR

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.301 Compensable... (a) No compensation for work-related injuries resulting...Compensation may only be paid for work-related injuries or...

2012-07-01

243

28 CFR 301.301 - Compensable and noncompensable injuries.  

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.301 Compensable... (a) No compensation for work-related injuries resulting...Compensation may only be paid for work-related injuries or...

2014-07-01

244

28 CFR 301.301 - Compensable and noncompensable injuries.  

Code of Federal Regulations, 2013 CFR

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.301 Compensable... (a) No compensation for work-related injuries resulting...Compensation may only be paid for work-related injuries or...

2013-07-01

245

28 CFR 301.301 - Compensable and noncompensable injuries.  

Code of Federal Regulations, 2010 CFR

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.301 Compensable... (a) No compensation for work-related injuries resulting...Compensation may only be paid for work-related injuries or...

2010-07-01

246

EMITTANCE COMPENSATION FOR MAGNETIZED BEAMS  

SciTech Connect

Emittance compensation is a well established technique for minimizing the emittance of an electron beam from a RF photo-cathode gun. Longitudinal slices of a bunch have a small emittance, but due to the longitudinal charge distribution of the bunch and time dependent RF fields they are not focused in the same way, so that the direction of their phase ellipses diverges in phase space and the projected emittance is much larger. Emittance compensation reverses the divergence. At the location where the slopes of the phase ellipses coincide the beam is accelerated, so that the space charge forces are reduced. A recipe for emittance compensation is given in. For magnetized beams (where the angular momentum is non-zero) such emittance compensation is not sufficient because variations in the slice radius lead to variations in the angular speed and therefore to an increase of emittance in the rotating game. We describe a method and tools for a compensation that includes the beam magnetization.

KEWISCH,J.; CHANG, X.

2007-06-25

247

Static synchronous series compensator: A solid-state approach to the series compensation of transmission lines  

Microsoft Academic Search

This paper describes an active approach to series line compensation, in which a synchronous voltage source, implemented by a gate turn-off thyristor (GTO) based voltage-sourced inverter, is used to provide controllable series compensation. This compensator, called Static Synchronous Series Compensator (SSSC), can provide controllable compensating voltage over an identical capacitive and inductive range, independently of the magnitude of the line

L. Gyugyi; C. D. Schauder; K. K. Sen

1997-01-01

248

Compensation and Recovery From Injury  

PubMed Central

Workers' compensation laws influence recovery from injury. They affect the cause of disease, access to care, diagnostic evaluation, treatment, response to treatment and residual disability. Paradoxically, financial compensation may discourage return to work, the appeal process may increase disability, an open claim may inhibit return to work and recovering patients may be unable to return to work. Physicians may help improve the prospects of returning patients to work by providing care that is medical, caring and independent. It is essential that the treatment of back pain be based on the known natural history and on the understanding that the management of acute pain differs from that of chronic pain. Increased awareness of the factors controlling return to work should motivate legislative bodies, labor and industry to alter those features of the compensation system that interfere with the return to work of injured workers. PMID:6233794

Beals, Rodney K.

1984-01-01

249

Compensation for electrical converter nonlinearities  

DOEpatents

Systems and methods are provided for delivering energy from an input interface to an output interface. An electrical system includes an input interface, an output interface, an energy conversion module between the input interface and the output interface, an inductive element between the input interface and the energy conversion module, and a control module. The control module determines a compensated duty cycle control value for operating the energy conversion module to produce a desired voltage at the output interface and operates the energy conversion module to deliver energy to the output interface with a duty cycle that is influenced by the compensated duty cycle control value. The compensated duty cycle control value is influenced by the current through the inductive element and accounts for voltage across the switching elements of the energy conversion module.

Perisic, Milun; Ransom, Ray M; Kajouke, Lateef A

2013-11-19

250

Super-Resolution Image with Estimated High Frequency Compensated Algorithm  

E-print Network

concept is to use signal processing techniques to obtain a high resolution (HR) image from observed single including video surveillance, medical imaging, satellite imaging, and video delivery and playback. SR image interpolation methods to enlarge the image, and then process it according to Iterative Back

Chang, Pao-Chi

251

Optical pulse compression using the combination of phase modulation and high-order dispersion compensation  

NASA Astrophysics Data System (ADS)

Optical pulse compression using high-order dispersion compensation is proposed and theoretically analyzed. Firstly, the required dispersion profile for the high-order dispersion compensation is derived, according to the linear chirp and the nonlinear chirp of a phase-modulated continuous-wave (CW) laser source. With the use of the high-order dispersion compensation, such as the combination compensation of the second order dispersion (SOD) and the fourth order dispersion (FOD), an efficient pulse compression having a less time-bandwidth product and a greater peak power is realized. A sampled fiber Bragg grating (FBG) with both the SOD and the FOD is then designed using the equivalent chirp and the reconstruction algorithm. Finally, in the numerical simulation an optical pulse with a time-bandwidth product of 0.79 is generated via high-order dispersion compensation that is performed by using the sampled FBG.

Deng, Guo; Pan, Wei; Zou, Xihua

2010-09-01

252

GA-Based Autonomous Compensator Design of 2-Degrees-Of-Freedom Positioning Controller  

NASA Astrophysics Data System (ADS)

This paper presents a novel Genetic Algorithm (GA) based autonomous compensator design for the fast-response and high-precision positioning of mechatronic systems. The positioning system is mainly composed of a robust 2-degrees-of-freedom (2DOF) controller based on the coprime factorization description. The feedback (FB) compensator in the 2DOF controller ensures the robust nature against the variations of load mechanical parameters. The feedforward (FF) compensator, on the other hand, allows the positioning to be fast and precise. In the controller design framework, the FB/FF compensators can be autonomously designed by GA, where both the structure and parameters of the compensators are optimized to achieve the desired robust positioning performance using ?-Analysis. The effectiveness of the proposed optimal design has been verified by experiments using a prototype of 2-mass resonant system.

Ito, Kazuaki; Iwasaki, Makoto; Matsui, Nobuyuki

253

Rate-Distortion Optimized Motion-Compensated Prediction for Packet Loss Resilient Video Coding  

Microsoft Academic Search

A rate-distortion optimized motion-compensated prediction method for robust video coding is proposed. Contrasting methods from the conventional literature, the proposed approach uses the expected reconstructed distortion after transmission, instead of the displaced frame difference in motion estimation. Initially, the end-to-end reconstructed distortion is estimated through a recursive per-pixel estimation algorithm. Then the total bit rate for motion-compensated encoding is predicted

Shuai Wan; Ebroul Izquierdo

2007-01-01

254

Instantaneous power compensation in three-phase systems by using p-q-r theory  

Microsoft Academic Search

This paper proposes a novel power compensation algorithm in three-phase four-wire power systems by using p-q-r theory. P-q-r theory is compared with two previous instantaneous power theories, p-q theory and cross-vector theory. P-q-r theory provides two-degrees of freedom to control the system currents by only compensating the instantaneous imaginary power without using any energy storage element. The definition of powers

Hyosung Kim; Frede Blaabjerg; Birgitte Bak-Jensen; Jlaeho Choi

2001-01-01

255

Instantaneous power compensation in three-phase systems by using p-q-r theory  

Microsoft Academic Search

This paper proposes a novel power compensation algorithm in three-phase four-wire systems by using p-q-r theory. The p-q-r theory is compared with two previous instantaneous power theories, p-q theory and cross vector theory. The p-q-r theory provides two-degrees of freedom to control the system currents by only compensating the instantaneous imaginary power without using any energy storage element. The definition

Hyosung Kim; Frede Blaabjerg; Birgitte Bak-Jensen; Jaeho Choi

2002-01-01

256

Randomized Algorithms  

Microsoft Academic Search

The last decade has witnessed a tremendous growth in the area of randomized algorithms.During this period, randomized algorithms went from being a tool in computational number theory to finding widespread application in many types of algorithms. Two benefits of randomization have spearheaded this growth: simplicity and speed. For many applications, a randomized algorithm is the simplest algorithm available, or the

Rajeev Motwani; Prabhakax Raghavan

1995-01-01

257

Numerical dispersion compensation for optical coherence tomography in the Wigner domain  

NASA Astrophysics Data System (ADS)

Dispersive objects result in a loss of resolution in time-domain optical coherence tomography (TD-OCT). A typical technique to compensate for this effect is to introduce dispersive material in the reference arm. This method however is not very effective, as the dispersion effect of the object is depth dependent. We implement a dispersion compensation algorithm in the Wigner domain for TD-OCT. This shift-variant numerical compensation approach is more efficient than the previously reported shift-invariant methods which required a deconvolution operation for every depth.

Sherif, Sherif; Huff, Kalon; Almuhtadi, Wahab; Flueraru, Costel; Mao, Youxin; Chang, Shoude

2007-06-01

258

Altitude Compensating Nozzle Concepts Evaluation  

NASA Technical Reports Server (NTRS)

This report contains the summary of work accomplished during summer of 2000 by Mr. Chad Hammons, undergraduate senior student, Mississippi State University/ERC in support of NASA/MSFC mission pertinent to Altitude compensating nozzle concepts evaluations. In particular, the development of automatic grid generator applicable in conducting sensitivity analysis involving Aerospike engine is described.

Soni, Bharat

2000-01-01

259

Synchrony - Cyberknife Respiratory Compensation Technology  

SciTech Connect

Studies of organs in the thorax and abdomen have shown that these organs can move as much as 40 mm due to respiratory motion. Without compensation for this motion during the course of external beam radiation therapy, the dose coverage to target may be compromised. On the other hand, if compensation of this motion is by expansion of the margin around the target, a significant volume of normal tissue may be unnecessarily irradiated. In hypofractionated regimens, the issue of respiratory compensation becomes an important factor and is critical in single-fraction extracranial radiosurgery applications. CyberKnife is an image-guided radiosurgery system that consists of a 6-MV LINAC mounted to a robotic arm coupled through a control loop to a digital diagnostic x-ray imaging system. The robotic arm can point the beam anywhere in space with 6 degrees of freedom, without being constrained to a conventional isocenter. The CyberKnife has been recently upgraded with a real-time respiratory tracking and compensation system called Synchrony. Using external markers in conjunction with diagnostic x-ray images, Synchrony helps guide the robotic arm to move the radiation beam in real time such that the beam always remains aligned with the target. With the aid of Synchrony, the tumor motion can be tracked in three-dimensional space, and the motion-induced dosimetric change to target can be minimized with a limited margin. The working principles, advantages, limitations, and our clinical experience with this new technology will be discussed.

Ozhasoglu, Cihat [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, PA (United States)], E-mail: ozhasogluc@upmc.edu; Saw, Cheng B.; Chen Hungcheng; Burton, Steven; Komanduri, Krishna; Yue, Ning J.; Huq, Saiful M.; Heron, Dwight E. [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, PA (United States)

2008-07-01

260

Clarification of Workmen's Compensation Insurance.  

ERIC Educational Resources Information Center

This document attempts to answer questions resulting from the 1972 Michigan Supreme Court Ruling relative to agricultural employees under the Workmen's Compensation Act (WCA). The sections of this paper outline a history of the WCA; employers covered; definition of "regularly employ"; clarification of "thirteen weeks"; employees (minors, partners,

Shapley, Allen E.

261

Voltage Fluctuation Compensator for Shinkansen  

NASA Astrophysics Data System (ADS)

In AC electric Railway, three-phase voltage is changed into the single-phase circuit of two circuits with the Scott-connected transformer. If it becomes large unbalancing of the load between single-phase circuits, voltage fluctuation becomes large on three-phase side. Then, Railway Static Power Conditioner (RPC) was developed for the purpose of controlling voltage fluctuation on three-phase side. An RPC is comprised of a pair of self-commutated PWM inverters. These inverters connect the main phase and teaser feeding buses, coupled with a DC side capacitor such as a Back-To-Back (BTB) converter. In this way, the two self-commutated inverters can act as a static var compensator (SVC) to compensate for the reactive power and as an active power accommodator from one feeding bus to another. 20MVA/60kV RPCs started commercial operation in 2002 at each two substations on the newly extended Tohoku Shinkansen for compensating voltage fluctuation on three-phase side caused by traction loads, absorbing harmonic current. The results of operational testing indicate that an RPC can accommodate single-phase loads such as those of PWM-controlled Shinkansen and thyristor phase-controlled Shinkansen, and handle the exciting rush current of transformers, as well as compensate for harmonics successfully.

Uzuka, Tetsuo; Ikedo, Shouji; Ueda, Keiji; Mochinaga, Yoshifumi; Funahashi, Sadao; Ide, Koiti

262

Compensation of School District Personnel  

Microsoft Academic Search

Recently considerable attention has been focused on the inadequacy of presently used methods of compensating school district personnel. The increasing incidence of teacher strikes in many school districts has established the need for an effective alternative to the inherent rigidity of the commonly used fixed step salary schedule. The purpose of this study is to propose one such alternative that

James E. Bruno

1971-01-01

263

Managerial discretion and executives' compensation  

Microsoft Academic Search

Purpose The purpose of this paper is to identify the reasons for the differences of executives' compensation across industries from the managerial discretion perspective. Design\\/methodology\\/approach Based on the data from 37 manufacturing industries from 2002 to 2007 in China, managerial discretion for each industry is calculated regarding to the conception raised by Hambrick and Finkelstein which is further

Runtian Jing; Yuanyuan Wan; Xia Gao

2010-01-01

264

Compensation of Navajo Uranium Miners  

NSDL National Science Digital Library

This site addresses policy issues of the compensation of Navajo uranium miners. The site provides an annotated index of current issues, legislation, papers and presentations, books, and links that lead to more information on uranium miners. Imbedded links throughout the text lead to related information.

Project, World I.

265

Minimum Wage Versus Minimum Compensation.  

National Technical Information Service (NTIS)

The paper's objective is to determine whether any wage increases produced by a minimum wage are offset by reductions in wage growth. If this occurs, the minimum wage is effectively avoided by employers through the reallocation of compensation to current w...

E. P. Lazear, F. H. Miller

1980-01-01

266

Can Education Compensate for Society?  

ERIC Educational Resources Information Center

The extent to which education can compensate for social disadvantage is a matter of political controversy, especially in the context of policies for social mobility. On the one hand, to blame poor achievement on social class or poverty was seen to dodge the professional responsibility of teachers. On the other, the strong correlation between

Pring, Richard

2011-01-01

267

Perks and Culture Competitive compensation  

E-print Network

Perks and Culture · Competitive compensation · Merit raises and performance bonuses · 401(k) plan controls and analytic tools to automate, monitor and control the two-way flow of energy across operations outages faster allow consumers to manage energy usage right down to the individual networked appliance

Ghosh, Joydeep

268

Autocollimating compensator for controlling aspheric optical surfaces  

NASA Astrophysics Data System (ADS)

A compensator (null-corrector) for testing aspheric optical surfaces is proposed, which enables (i) independent verification of optical elements and assembling of the compensator itself, and (ii) ascertaining the compensator position in a control layout for a specified aspheric surface. The compensator consists of three spherical lenses made of the same glass. In this paper, the scope of the compensator expanded to a surface speed f/2.3; a conceptual example for a nominal primary of Hubble Space Telescope is given. The autocollimating design allows significant reducing difficulties associated with practical use of lens compensators.

Terebizh, V. Yu.

2014-05-01

269

Atmospheric Turbulence Compensation with Laser Phase Shifting Interferometry  

E-print Network

Laser guide stars with adaptive optics allow astronomical image correction in the absence of a natural guide star. Single guide star systems with a star created in the earth's sodium layer can be used to correct the wavefront in the near infrared spectral regime for 8-m class telescopes. For possible future telescopes of larger sizes, or for correction at shorter wavelengths, the use of a single guide star is ultimately limited by focal anisoplanatism that arises from the finite height of the guide star. To overcome this limitation we propose to overlap coherently pulsed laser beams that are expanded over the full aperture of the telescope, traveling upwards along the same path which light from the astronomical object travels downwards. Imaging the scattered light from the resultant interference pattern with a camera gated to a certain height above the telescope, and using phase shifting interferometry we have found a method to retrieve the local wavefront gradients. By sensing the backscattered light from two different heights, one can fully remove the cone effect, which can otherwise be a serious handicap to the use of laser guide stars at shorter wavelengths or on larger telescopes. Using two laser beams multiconjugate correction is possible, resulting in larger corrected fields. With a proper choice of laser, wavefront correction could be expanded to the visible regime and, due to the lack of a cone effect, the method is applicable to any size of telescope. Finally the position of the laser spot could be imaged from the side of the main telescope against a bright background star to retrieve tip-tilt information, which would greatly improve the sky coverage of the system.

S. Rabien; F. Eisenhauer; R. Genzel; R. I. Davies; T. Ott

2006-01-21

270

GIFTS SM EDU Data Processing and Algorithms  

NASA Technical Reports Server (NTRS)

The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) Sensor Module (SM) Engineering Demonstration Unit (EDU) is a high resolution spectral imager designed to measure infrared (IR) radiances using a Fourier transform spectrometer (FTS). The GIFTS instrument employs three Focal Plane Arrays (FPAs), which gather measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The raw interferogram measurements are radiometrically and spectrally calibrated to produce radiance spectra, which are further processed to obtain atmospheric profiles via retrieval algorithms. This paper describes the processing algorithms involved in the calibration stage. The calibration procedures can be subdivided into three stages. In the pre-calibration stage, a phase correction algorithm is applied to the decimated and filtered complex interferogram. The resulting imaginary part of the spectrum contains only the noise component of the uncorrected spectrum. Additional random noise reduction can be accomplished by applying a spectral smoothing routine to the phase-corrected blackbody reference spectra. In the radiometric calibration stage, we first compute the spectral responsivity based on the previous results, from which, the calibrated ambient blackbody (ABB), hot blackbody (HBB), and scene spectra can be obtained. During the post-processing stage, we estimate the noise equivalent spectral radiance (NESR) from the calibrated ABB and HBB spectra. We then implement a correction scheme that compensates for the effect of fore-optics offsets. Finally, for off-axis pixels, the FPA off-axis effects correction is performed. To estimate the performance of the entire FPA, we developed an efficient method of generating pixel performance assessments. In addition, a random pixel selection scheme is designed based on the pixel performance evaluation.

Tian, Jialin; Johnson, David G.; Reisse, Robert A.; Gazarik, Michael J.

2007-01-01

271

Optimization Algorithms  

Microsoft Academic Search

\\u000a The right choice of an optimization algorithm can be crucially important in finding the right solutions for a given optimization\\u000a problem. There exist a diverse range of algorithms for optimization, including gradient-based algorithms, derivative-free\\u000a algorithms and metaheuristics. Modern metaheuristic algorithms are often nature-inspired, and they are suitable for global\\u000a optimization. In this chapter, we will briefly introduce optimization algorithms such

Xin-She Yang

272

A Cenozoic record of the equatorial Pacific carbonate compensation depth.  

PubMed

Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5?kilometres during the early Cenozoic (approximately 55?million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth. PMID:22932385

Plike, Heiko; Lyle, Mitchell W; Nishi, Hiroshi; Raffi, Isabella; Ridgwell, Andy; Gamage, Kusali; Klaus, Adam; Acton, Gary; Anderson, Louise; Backman, Jan; Baldauf, Jack; Beltran, Catherine; Bohaty, Steven M; Bown, Paul; Busch, William; Channell, Jim E T; Chun, Cecily O J; Delaney, Margaret; Dewangan, Pawan; Dunkley Jones, Tom; Edgar, Kirsty M; Evans, Helen; Fitch, Peter; Foster, Gavin L; Gussone, Nikolaus; Hasegawa, Hitoshi; Hathorne, Ed C; Hayashi, Hiroki; Herrle, Jens O; Holbourn, Ann; Hovan, Steve; Hyeong, Kiseong; Iijima, Koichi; Ito, Takashi; Kamikuri, Shin-ichi; Kimoto, Katsunori; Kuroda, Junichiro; Leon-Rodriguez, Lizette; Malinverno, Alberto; Moore, Ted C; Murphy, Brandon H; Murphy, Daniel P; Nakamura, Hideto; Ogane, Kaoru; Ohneiser, Christian; Richter, Carl; Robinson, Rebecca; Rohling, Eelco J; Romero, Oscar; Sawada, Ken; Scher, Howie; Schneider, Leah; Sluijs, Appy; Takata, Hiroyuki; Tian, Jun; Tsujimoto, Akira; Wade, Bridget S; Westerhold, Thomas; Wilkens, Roy; Williams, Trevor; Wilson, Paul A; Yamamoto, Yuhji; Yamamoto, Shinya; Yamazaki, Toshitsugu; Zeebe, Richard E

2012-08-30

273

Compensation Policies under Agrarian Reform Programs.  

National Technical Information Service (NTIS)

Compensation problems arise whenever land is redistributed under a land reform program. Among these are: difficulties in determining a reasonable value for the land, effects of inflation on the value of the compensation, effects of the form of compensatio...

J. T. Steele

1964-01-01

274

71 FR 78338 - Executive Compensation Disclosure  

Federal Register 2010, 2011, 2012, 2013

...RIN 3235-AI80 Executive Compensation Disclosure AGENCY: Securities and Exchange Commission...interim final rules, amendments to the disclosure requirements for executive and director...Table and Director Compensation Table disclosure with respect to stock awards and...

2006-12-29

275

Connected Companies' Compensation Alexander W. Butler  

E-print Network

is consistent with higher compensation being the quid pro quo for information flow from firm to fund. Contact compensation being the quid pro quo for information flow from firm to fund. #12;1 1 Introduction Social

276

Supplemental Compensation Involving Work Within the University  

E-print Network

Supplemental Compensation Involving Work Within the University Policy 3.35 Applies to: Staff Policy to receive supplemental compensation if release time is not a feasible option. Performance of work outside for Supplemental Compensation as they receive overtime pay or compensatory time off for additional work performed.1

Howat, Ian M.

277

Race and compensation in professional football  

Microsoft Academic Search

Although there have been numerous studies on the effect of race on the compensation of National Basketball Association and Major League Baseball players, there have been only three prior studies that investigated the effect of race on the compensation of National Football League (NFL) players. Two found no evidence of racial discrimination in NFL player compensation, while one found that,

Mark Gius; Donn Johnson

2000-01-01

278

Genetic algorithms  

NASA Technical Reports Server (NTRS)

Genetic algorithms are mathematical, highly parallel, adaptive search procedures (i.e., problem solving methods) based loosely on the processes of natural genetics and Darwinian survival of the fittest. Basic genetic algorithms concepts are introduced, genetic algorithm applications are introduced, and results are presented from a project to develop a software tool that will enable the widespread use of genetic algorithm technology.

Wang, Lui; Bayer, Steven E.

1991-01-01

279

Causal compensated perturbations in cosmology  

NASA Technical Reports Server (NTRS)

A theoretical framework is developed to calculate linear perturbations in the gravitational and matter fields which arise causally in response to the presence of stiff matter sources in a FRW cosmology. It is shown that, in order to satisfy energy and momentum conservation, the gravitational fields of the source must be compensated by perturbations in the matter and gravitational fields, and the role of such compensation in containing the initial inhomogeneities in their subsequent evolution is discussed. A complete formal solution is derived in terms of Green functions for the perturbations produced by an arbitrary source in a flat universe containing cold dark matter. Approximate Green function solutions are derived for the late-time density perturbations and late-time gravitational waves in a universe containing a radiation fluid. A cosmological energy-momentum pseudotensor is defined to clarify the nature of energy and momentum conservation in the expanding universe.

Veeraraghavan, Shoba; Stebbins, Albert

1990-01-01

280

Quantum Algorithms  

E-print Network

This article surveys the state of the art in quantum computer algorithms, including both black-box and non-black-box results. It is infeasible to detail all the known quantum algorithms, so a representative sample is given. This includes a summary of the early quantum algorithms, a description of the Abelian Hidden Subgroup algorithms (including Shor's factoring and discrete logarithm algorithms), quantum searching and amplitude amplification, quantum algorithms for simulating quantum mechanical systems, several non-trivial generalizations of the Abelian Hidden Subgroup Problem (and related techniques), the quantum walk paradigm for quantum algorithms, the paradigm of adiabatic algorithms, a family of ``topological'' algorithms, and algorithms for quantum tasks which cannot be done by a classical computer, followed by a discussion.

Michele Mosca

2008-08-04

281

Compensation effects in hadron calorimeters  

Microsoft Academic Search

The pros and cons of utilizing a fissionable material such as ²³⁸U to compensate for the nuclear binding energy losses in a hadron calorimeter are discussed. Fissionable material can return some lost energy to the particle cascade in terms of low-energy neutrons and gamma rays, but electromagnetic sampling inefficiencies (often called transition effects) and the detection medium which tries to

T. A. Gabriel; B. L. Bishop; J. Brau; A. Di Ciaccio; M. Goodman; R. Wilson

1984-01-01

282

Compensation Effects in Hadron Calorimeters  

Microsoft Academic Search

The pros and cons of utilizing a fissionable material such as ²³⁸U to compensate for the nuclear binding energy losses in a hadron calorimeter are discussed. Fissionable material can return some lost energy to the particle cascade in terms of low-energy neutrons and gamma rays, but electromagnetic sampling inefficiencies (often called transition effects) and the detection medium which tries to

T. A. Gabriel; B. L. Bishop; J. Brau; A. di Ciaccio; M. Goodman; R. Wilson

1985-01-01

283

Simulation experiment of high energy laser propagation in the atmosphere  

Microsoft Academic Search

Simulation experiment of adaptive optics compensation to thermal blooming phase distortion induced by high energy laser propagation in the atmosphere are carried out. The results of spot pattern and Strehl ratio in the focal plane are obtained when the adaptive optics system is in the open or closed loop shape. The effect of adaptive optics compensation is prominent when the

Chun-Hong Qiao; Xiao-Xing Feng; Cheng-Yu Fan; Ying-Jian Wang

2009-01-01

284

Performance analysis of compensation current extraction techniques for 3?, 3-wire shunt active power filter under unbalanced supply  

Microsoft Academic Search

Active power filters are effective in mitigating line current harmonics and compensating for the reactive power in the line. Many papers comparing the performance of active power filter extraction algorithms are found in the literature, but there is no explicit mention about the suitability of any particular extraction algorithm under all conditions. Hence this paper is an attempt to compare

J. M. Gonda; V. A. Adithya; S. S. David

2009-01-01

285

Study on Reactive Automatic Compensation System Design  

NASA Astrophysics Data System (ADS)

At present, low-voltage side of transformer is public in urban distribution network, as inductive load of household appliances is increasing, the power factor decreased, this lead to a large loss of public transformer low voltage side, the supply voltage indicators can not meet user's requirements. Therefore, the design of reactive power compensation system has become another popular research. This paper introduces the principle of reactive power compensation, analyzes key technologies of reactive power compensation, design an overall program of reactive power automatic compensation system to conquer various deficiencies of reactive power automatic compensation equipment.

Zhe, Sun; Qingyang, Liang; Peiqing, Luo; Chenfei, Zhang

286

An investigation of Bjerknes Compensation in the Southern Ocean in the CCSM4  

SciTech Connect

This project aims to understand the relationship between poleward oceanic and atmospheric heat transport in the Southern Ocean by analyzing output from the community Climate System Model Version 4 (CCSM4). In particular, time series of meridional heat transport in both the atmosphere and the ocean are used to study whether variability in ocean heat transport is balanced by opposing changes in atmospheric heat transport, called Bjerknes Compensation. It is shown that the heat storage term in the Southern Ocean has a significant impact on the oceanic heat budget; as a result, no robust coherences between oceanic and atmospheric heat transports could be found at these southern latitudes.

Weijer, Wilbert [Los Alamos National Laboratory; Kinstle, Caroline M. [Los Alamos National Laboratory

2012-08-28

287

LPV Antiwindup Compensation for Enhanced Flight Control Performance  

NASA Technical Reports Server (NTRS)

In this paper, we propose a saturation control scheme for linear parameter-varying (LPV) systems from an antiwindup control perspective. The proposed control approach is advantageous because it can be thought of as an augmented control algorithm from the existing control system. Moreover, the synthesis condition for an antiwindup compensator is formulated as a linear matrix inequality (LMI) optimization problem and can be solved efficiently. We have applied the LPV antiwindup controller to an F-16 longitudinal autopilot control system design to enhance aircraft safety and improve flight quality in a high angle of attack region.

Lu, Bei; Wu, Fen; Kim, Sung-Wan

2003-01-01

288

Improving calibration accuracy of structured light systems using plane-based residual error compensation  

NASA Astrophysics Data System (ADS)

The performance of a structured light system (SLS) highly depends on its calibration especially in applications such as surface metrology and product quality control where high accuracy is required. Motivated by building a real-time highly accurate flatness measurement system, we propose a plane-based residual error compensation algorithm for improving the calibration accuracy of SLSs. Following the highly accurate procedure of geometric calibration using circular control points, the proposed algorithm enforces the planar constraint on the three-dimensional reconstruction of the circular control points, which are projected on a perfect plane, to further reduce the residual calibration error. Our method compensates for the largest proportion of the residual error, in most cases being the model error of the lens distortion in the system. Experimental results show that the compensation elevates the calibration accuracy to a higher level-the planarity error is reduced by 70% and this accuracy is comparable to a well-reputed industrial mechanical measuring machine.

Han, Dong; Chimienti, Antonio; Menga, Giuseppe

2013-10-01

289

Novel dispersion compensation method for cross-coupling measurement in PM-PCF based on OCDP  

NASA Astrophysics Data System (ADS)

For polarization maintaining photonic crystal fiber (PM-PCF), the cross-coupling measurement can be severely affected by interferogram broadening, due to the large inter-mode chromatic dispersion. In this paper, a novel dispersion compensation method is proposed to mitigate the influence, including a frequency domain algorithm and investigation of the dispersion coefficient for a phase packet in algorithm. A numerical simulation and measurement of birefringence as a function of wavelength reveal that the dispersion coefficient in PM-PCF is much larger than that in PANDA-PM fiber. After compensation, the accuracy of coupling strength measured can be restored and spatial resolution is improved. Experiments show the compensation provides high accuracy with average relative error less than 0.31% and spatial resolution improved 4.1 times.

Jin, Jing; Wang, Shu; Song, Jingming; Song, Ningfang; Sun, Zuoming; Jiang, Man

2013-10-01

290

A smart high accuracy silicon piezoresistive pressure sensor temperature compensation system.  

PubMed

Theoretical analysis in this paper indicates that the accuracy of a silicon piezoresistive pressure sensor is mainly affected by thermal drift, and varies nonlinearly with the temperature. Here, a smart temperature compensation system to reduce its effect on accuracy is proposed. Firstly, an effective conditioning circuit for signal processing and data acquisition is designed. The hardware to implement the system is fabricated. Then, a program is developed on LabVIEW which incorporates an extreme learning machine (ELM) as the calibration algorithm for the pressure drift. The implementation of the algorithm was ported to a micro-control unit (MCU) after calibration in the computer. Practical pressure measurement experiments are carried out to verify the system's performance. The temperature compensation is solved in the interval from -40 to 85 C. The compensated sensor is aimed at providing pressure measurement in oil-gas pipelines. Compared with other algorithms, ELM acquires higher accuracy and is more suitable for batch compensation because of its higher generalization and faster learning speed. The accuracy, linearity, zero temperature coefficient and sensitivity temperature coefficient of the tested sensor are 2.57% FS, 2.49% FS, 8.1 10(-5)/C and 29.5 10(-5)/C before compensation, and are improved to 0.13%FS, 0.15%FS, 1.17 10(-5)/C and 2.1 10(-5)/C respectively, after compensation. The experimental results demonstrate that the proposed system is valid for the temperature compensation and high accuracy requirement of the sensor. PMID:25006998

Zhou, Guanwu; Zhao, Yulong; Guo, Fangfang; Xu, Wenju

2014-01-01

291

A Smart High Accuracy Silicon Piezoresistive Pressure Sensor Temperature Compensation System  

PubMed Central

Theoretical analysis in this paper indicates that the accuracy of a silicon piezoresistive pressure sensor is mainly affected by thermal drift, and varies nonlinearly with the temperature. Here, a smart temperature compensation system to reduce its effect on accuracy is proposed. Firstly, an effective conditioning circuit for signal processing and data acquisition is designed. The hardware to implement the system is fabricated. Then, a program is developed on LabVIEW which incorporates an extreme learning machine (ELM) as the calibration algorithm for the pressure drift. The implementation of the algorithm was ported to a micro-control unit (MCU) after calibration in the computer. Practical pressure measurement experiments are carried out to verify the system's performance. The temperature compensation is solved in the interval from ?40 to 85 C. The compensated sensor is aimed at providing pressure measurement in oil-gas pipelines. Compared with other algorithms, ELM acquires higher accuracy and is more suitable for batch compensation because of its higher generalization and faster learning speed. The accuracy, linearity, zero temperature coefficient and sensitivity temperature coefficient of the tested sensor are 2.57% FS, 2.49% FS, 8.1 10?5/C and 29.5 10?5/C before compensation, and are improved to 0.13%FS, 0.15%FS, 1.17 10?5/C and 2.1 10?5/C respectively, after compensation. The experimental results demonstrate that the proposed system is valid for the temperature compensation and high accuracy requirement of the sensor. PMID:25006998

Zhou, Guanwu; Zhao, Yulong; Guo, Fangfang; Xu, Wenju

2014-01-01

292

Banker Compensation and Confirmation Bias  

E-print Network

Banker Compensation and Con?rmation Bias1 Hamid Sabourian, University of Cambridge2 Anne C. Sibert, Birkbeck, University of London and CEPR3 24 Mar 2009 1We are grateful to Willem Buiter and Mike Oaksford for helpful comments. Financial support from... of London, Malet Street, London WC1E 7HX, UK; Email: asibert@econ.bbk.ac.uk. Abstract Con?rmation bias refers to cognitive errors that bias one towards one?s own prior beliefs. A vast empirical literature documents its existence and psychologists identify...

Sabourian, Hamid; Sibert, A C

293

Charge amplifier with bias compensation  

DOEpatents

An ion beam uniformity monitor for very low beam currents using a high-sensitivity charge amplifier with bias compensation. The ion beam monitor is used to assess the uniformity of a raster-scanned ion beam, such as used in an ion implanter, and utilizes four Faraday cups placed in the geometric corners of the target area. Current from each cup is integrated with respect to time, thus measuring accumulated dose, or charge, in Coulombs. By comparing the dose at each corner, a qualitative assessment of ion beam uniformity is made possible. With knowledge of the relative area of the Faraday cups, the ion flux and areal dose can also be obtained.

Johnson, Gary W. (Livermore, CA)

2002-01-01

294

Efficient Geolocation of InSAR Images from Motion Compensation Processors  

Microsoft Academic Search

We present an efficient and closed-form algorithm for the geolocation of InSAR images resulting from data processors using motion compensation methods in which the known orbits are corrected and processed to a circular arc reference track. We outline here a derivation utilizing the SCH coordinate system, although our approach may be readily applied to any such processor with suitable changes

C. Wortham; H. A. Zebker

2010-01-01

295

Synchronous disturbance compensation in active magnetic bearings using bias current excitation  

Microsoft Academic Search

This paper proposes a new approach for simultaneous compensation of two synchronous periodic disturbances in active magnetic bearings; sensor runout and mass unbalance. Using Lyapunov's method, a novel adaptive algorithm is developed to uniquely determine the harmonic components of both disturbances and guarantee asymptotic stability of the rotor geometric center about the origin. By varying magnetic stiffness through excitation of

Joga D. Setiawan; Ranjan Mukherjee; Eric H. Maslen

2001-01-01

296

Adaptive Vibration Compensation Control Research on Rotor in Active Magnetic Bearing System  

Microsoft Academic Search

In active bearing system, the synchronous periodic disturbances are mainly caused by the sensor run-out and mass unbalance. The rotational accuracy of rotor is mainly affected by this synchronous disturbance. To improve the rotational accuracy of magnetically levitated rotor, this paper proposed a new approach for simultaneous compensation of periodic disturbances in active magnetic bearings system. A novel adaptive algorithm

Tao Zhang

2010-01-01

297

A Globally Stable Saturated Desired Compensation Adaptive Robust Control For Linear Motor Systems With Comparative Experiments  

E-print Network

A Globally Stable Saturated Desired Compensation Adaptive Robust Control For Linear Motor Systems with much improved tracking performance. The algorithm is tested on a linear motor drive system which has factors such as friction and hysteresis affect system behavior significantly and are rather difficult

Yao, Bin

298

Numerical Algorithms  

NSDL National Science Digital Library

CSC 325. (MAT 325) Numerical Algorithms (3) Prerequisite: CSC 112 or 121, MAT 162. An introduction to the numerical algorithms fundamental to scientific computer work. Includes elementary discussion of error, polynomial interpolation, quadrature, linear systems of equations, solution of nonlinear equations and numerical solution of ordinary differential equations. The algorithmic approach and the efficient use of the computer are emphasized.

Tagliarini, Gene

2003-04-21

299

Multiexposure and multifocus image fusion with multidimensional camera shake compensation  

NASA Astrophysics Data System (ADS)

Multiexposure image fusion algorithms are used for enhancing the perceptual quality of an image captured by sensors of limited dynamic range. This is achieved by rendering a single scene based on multiple images captured at different exposure times. Similarly, multifocus image fusion is used when the limited depth of focus on a selected focus setting of a camera results in parts of an image being out of focus. The solution adopted is to fuse together a number of multifocus images to create an image that is focused throughout. A single algorithm that can perform both multifocus and multiexposure image fusion is proposed. This algorithm is a new approach in which a set of unregistered multiexposure/focus images is first registered before being fused to compensate for the possible presence of camera shake. The registration of images is done via identifying matching key-points in constituent images using scale invariant feature transforms. The random sample consensus algorithm is used to identify inliers of SIFT key-points removing outliers that can cause errors in the registration process. Finally, the coherent point drift algorithm is used to register the images, preparing them to be fused in the subsequent fusion stage. For the fusion of images, a new approach based on an improved version of a wavelet-based contourlet transform is used. The experimental results and the detailed analysis presented prove that the proposed algorithm is capable of producing high-dynamic range (HDR) or multifocus images by registering and fusing a set of multiexposure or multifocus images taken in the presence of camera shake. Further, comparison of the performance of the proposed algorithm with a number of state-of-the art algorithms and commercial software packages is provided. In particular, our literature review has revealed that this is one of the first attempts where the compensation of camera shake, a very likely practical problem that can result in HDR image capture using handheld devices, has been addressed as a part of a multifocus and multiexposure image enhancement system.

Gomez, Alexis Lluis; Saravi, Sara; Edirisinghe, Eran A.

2013-10-01

300

Adaptive-Optics Compensation by Distributed Beacons for Non-Kolmogorov Turbulence  

Microsoft Academic Search

In optical propagation through atmospheric turbulence, the performance of compensation with adaptive optics depends on a beacon s spatial distribution. With distributed beacons, the inefficiency of the modal correction, which is defined as the ratio of the anisoplanatic error of the j th mode and the Zernike-coefficient variance, is derived by use of the wave-front expansion on the Zernike polynomials

Changhui Rao; Wenhan Jiang; Ning Ling

2001-01-01

301

Imaging Algorithm of Missile-Borne SAR  

Microsoft Academic Search

Compared with the tradition synthesis aperture radar (SAR), the missile borne SAR has the characteristics including big squint angle, non-straight movement with non-constant velocity and high flight speed, which bring forward a crucial great of requirements for real time performance and the precision of the motion compensation. The proposed algorithm based on chirp scaling for high squint missile borne SAR

Xu Huili

2008-01-01

302

CEO Compensation and Hospital Financial Performance  

PubMed Central

Growing interest in pay-for-performance and the level of CEO pay raises questions about the link between performance and compensation in the health sector. This study compares the compensation of non-profit hospital Chief Executive Officers (CEOs) in Ontario, Canada to the three longest reported and most used measures of hospital financial performance. Our sample consisted of 132 CEOs from 92 hospitals between 1999 and 2006. Unbalanced panel data were analyzed using fixed effects regression. Results suggest that CEO compensation was largely unrelated to hospital financial performance. Inflation-adjusted salaries appeared to increase over time independent of hospital performance, and hospital size was positively correlated with CEO compensation. The apparent upward trend in salary despite some declines in financial performance challenges the fundamental assumption underlying this paper, that is, financial performance is likely linked to CEO compensation in Ontario. Further research is needed to understand long-term performance related to compensation incentives. PMID:19605619

Reiter, Kristin L.; Sandoval, Guillermo A.; Brown, Adalsteinn D.; Pink, George H.

2010-01-01

303

CEO compensation and hospital financial performance.  

PubMed

Growing interest in pay-for-performance and the level of chief executive officers' (CEOs') pay raises questions about the link between performance and compensation in the health sector. This study compares the compensation of nonprofit hospital CEOs in Ontario, Canada to the three longest reported and most used measures of hospital financial performance. Our sample consisted of 132 CEOs from 92 hospitals between 1999 and 2006. Unbalanced panel data were analyzed using fixed effects regression. Results suggest that CEO compensation was largely unrelated to hospital financial performance. Inflation-adjusted salaries appeared to increase over time independent of hospital performance, and hospital size was positively correlated with CEO compensation. The apparent upward trend in salary despite some declines in financial performance challenges the fundamental assumption underlying this article, that is, financial performance is likely linked to CEO compensation in Ontario. Further research is needed to understand long-term performance related to compensation incentives. PMID:19605619

Reiter, Kristin L; Sandoval, Guillermo A; Brown, Adalsteinn D; Pink, George H

2009-12-01

304

Adaptive image backlight compensation for mobile phone users  

NASA Astrophysics Data System (ADS)

The user-friendliness and cost-effectiveness have contributed to the growing popularity of mobile phone cameras. However, images captured by such mobile phone cameras are easily distorted by a wide range of factors, such as backlight, over-saturation, and low contrast. Although several approaches have been proposed to solve the backlight problems, most of them still suffer from distorted background colors and high computational complexity. Thus, they are not deployable in mobile applications requiring real-time processing with very limited resources. In this paper, we present a novel framework to compensate image backlight for mobile phone applications based on an adaptive pixel-wise gamma correction which is computationally efficient. The proposed method is composed of two sequential stages: 1) illumination condition identification and 2) adaptive backlight compensation. Given images are classified into facial images and non-facial images to provide prior knowledge for identifying the illumination condition at first. Then we further categorize the facial images into backlight images and nonbacklight images based on local image statistics obtained from corresponding face regions. We finally compensate the image backlight using an adaptive pixel-wise gamma correction method while preserving global and local contrast effectively. To show the superiority of our algorithm, we compare our proposed method with other state-of-the-art methods in the literature.

Kong, Haejung; Jung, Chanho; Kim, Wonjun; Lee, Jaeho; Kim, Changick

2010-08-01

305

Compensation of low order aberrations with reflective beam shaping system  

NASA Astrophysics Data System (ADS)

Compensation of low order aberrations is essential for high power solid state slab laser. With the increase of output power, the peak-to-valley of wavefront distortion increase to dozens of micrometer. It's difficult to control the wavefront with deformable mirrors which always has limited stroke(<20?m). In this paper, a reflective beam shaping system is designed to shaping the beam spot from rectangular to squarer. The beam shaping system consists of two x-oriented cylindrical mirrors and two y-oriented cylindrical mirrors. Simulations of PID control algorithm for actively compensating of low-order aberrations with reflective beam shaping system are presented. It shows that different combinations of defocus, 0o astigmatism and 45 astigmatism, which is the main contributor of beam aberrations in slab laser, can be well compensated by adjustment of distance and rotation angle of mirrors. And the convergence is fast when the control error signal is set to a suitable combination of low order Zernike coefficients. For beam with wave aberrations (PtV=82.6?, RMS=18.2?, Z4=23.6, Z5=7.1, Z6=19.6), the adjustment of distance between mirrors is below 100mm, and the rotation angle about z-axis is below 2 degree. The wavefront aberrations are decreased to a low level (PV=0.16?, RMS=0.04?) which can be easily corrected later with DM.

Liu, Wenguang; Zhou, Qiong; Gu, Dianyu; Jiang, Zongfu

2014-05-01

306

Compensation Consultants and CEO Pay: UK Evidence  

Microsoft Academic Search

ABSTRACTManuscript Type: EmpiricalResearch Question\\/Issue: This paper provides new evidence on the effect of compensation consultants on CEO pay.Research Findings\\/Insights: We produce new evidence on the managerial power approach (MPA) to corporate governance by examining the influence of compensation consultants on CEO pay structures and the decision to hire a compensation consultant in the UK. We find evidence that is not

Georgios Voulgaris; Konstantinos Stathopoulos; Martin Walker

2010-01-01

307

Homotopy Algorithm for Fixed Order Mixed H2/H(infinity) Design  

NASA Technical Reports Server (NTRS)

Recent developments in the field of robust multivariable control have merged the theories of H-infinity and H-2 control. This mixed H-2/H-infinity compensator formulation allows design for nominal performance by H-2 norm minimization while guaranteeing robust stability to unstructured uncertainties by constraining the H-infinity norm. A key difficulty associated with mixed H-2/H-infinity compensation is compensator synthesis. A homotopy algorithm is presented for synthesis of fixed order mixed H-2/H-infinity compensators. Numerical results are presented for a four disk flexible structure to evaluate the efficiency of the algorithm.

Whorton, Mark; Buschek, Harald; Calise, Anthony J.

1996-01-01

308

33 CFR 136.241 - Compensation allowable.  

Code of Federal Regulations, 2010 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2010-07-01

309

33 CFR 136.229 - Compensation allowable.  

Code of Federal Regulations, 2010 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2010-07-01

310

33 CFR 136.223 - Compensation allowable.  

Code of Federal Regulations, 2012 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2012-07-01

311

33 CFR 136.205 - Compensation allowable.  

Code of Federal Regulations, 2010 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2010-07-01

312

33 CFR 136.217 - Compensation allowable.  

Code of Federal Regulations, 2013 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2013-07-01

313

33 CFR 136.241 - Compensation allowable.  

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2014-07-01

314

33 CFR 136.217 - Compensation allowable.  

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2014-07-01

315

33 CFR 136.229 - Compensation allowable.  

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2014-07-01

316

33 CFR 136.211 - Compensation allowable.  

Code of Federal Regulations, 2011 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2011-07-01

317

33 CFR 136.223 - Compensation allowable.  

Code of Federal Regulations, 2010 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2010-07-01

318

33 CFR 136.217 - Compensation allowable.  

Code of Federal Regulations, 2012 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2012-07-01

319

33 CFR 136.235 - Compensation allowable.  

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2014-07-01

320

33 CFR 136.235 - Compensation allowable.  

Code of Federal Regulations, 2012 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2012-07-01

321

33 CFR 136.241 - Compensation allowable.  

Code of Federal Regulations, 2012 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2012-07-01

322

33 CFR 136.217 - Compensation allowable.  

Code of Federal Regulations, 2010 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2010-07-01

323

33 CFR 136.241 - Compensation allowable.  

Code of Federal Regulations, 2013 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2013-07-01

324

33 CFR 136.235 - Compensation allowable.  

Code of Federal Regulations, 2011 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2011-07-01

325

33 CFR 136.211 - Compensation allowable.  

Code of Federal Regulations, 2012 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2012-07-01

326

33 CFR 136.205 - Compensation allowable.  

Code of Federal Regulations, 2013 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2013-07-01

327

33 CFR 136.223 - Compensation allowable.  

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2014-07-01

328

33 CFR 136.113 - Other compensation.  

Code of Federal Regulations, 2010 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT General Procedure ...

2010-07-01

329

33 CFR 136.241 - Compensation allowable.  

Code of Federal Regulations, 2011 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2011-07-01

330

33 CFR 136.229 - Compensation allowable.  

Code of Federal Regulations, 2012 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2012-07-01

331

33 CFR 136.229 - Compensation allowable.  

Code of Federal Regulations, 2011 CFR

...COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular...

2011-07-01

332

Log amplifier with pole-zero compensation  

DOEpatents

A logarithmic amplifier circuit provides pole-zero compensation for improved stability and response time over 6-8 decades of input signal frequency. The amplifier circuit includes a first operational amplifier with a first feedback loop which includes a second, inverting operational amplifier in a second feedback loop. The compensated output signal is provided by the second operational amplifier with the log elements, i.e., resistors, and the compensating capacitors in each of the feedback loops having equal values so that each break point or pole is offset by a compensating break point or zero.

Brookshier, William (Downers Grove, IL)

1987-01-01

333

Log amplifier with pole-zero compensation  

DOEpatents

A logarithmic amplifier circuit provides pole-zero compensation for improved stability and response time over 6-8 decades of input signal frequency. The amplifer circuit includes a first operational amplifier with a first feedback loop which includes a second, inverting operational amplifier in a second feedstock loop. The compensated output signal is provided by the second operational amplifier with the log elements, i.e., resistors, and the compensating capacitors in each of the feedback loops having equal values so that each break point is offset by a compensating break point or zero.

Brookshier, W.

1985-02-08

334

Refractive Index Compensation in Over-Determined Interferometric Systems  

PubMed Central

We present an interferometric technique based on a differential interferometry setup for measurement under atmospheric conditions. The key limiting factor in any interferometric dimensional measurement are fluctuations of the refractive index of air representing a dominating source of uncertainty when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of an over-determined interferometric setup where a reference length is derived from a mechanical frame made from a material with a very low thermal coefficient. The technique allows one to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range, acting as a tracking refractometer. The principle is demonstrated in an experimental setup. PMID:23202037

Lazar, Josef; Hola, Miroslava; Cip, Ondrej; Cizek, Martin; Hrabina, Jan; Buchta, Zdenek

2012-01-01

335

Refractive index compensation in over-determined interferometric systems.  

PubMed

We present an interferometric technique based on a differential interferometry setup for measurement under atmospheric conditions. The key limiting factor in any interferometric dimensional measurement are fluctuations of the refractive index of air representing a dominating source of uncertainty when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of an over-determined interferometric setup where a reference length is derived from a mechanical frame made from a material with a very low thermal coefficient. The technique allows one to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range, acting as a tracking refractometer. The principle is demonstrated in an experimental setup. PMID:23202037

Lazar, Josef; Hol, Miroslava; ?p, Ond?ej; ?ek, Martin; Hrabina, Jan; Buchta, Zden?k

2012-01-01

336

An adaptive guidance algorithm for an aerodynamically assisted orbital plane change maneuver. M.S. Thesis  

NASA Technical Reports Server (NTRS)

Using analysis results from the post trajectory optimization program, an adaptive guidance algorithm is developed to compensate for density, aerodynamic and thrust perturbations during an atmospheric orbital plane change maneuver. The maneuver offers increased mission flexibility along with potential fuel savings for future reentry vehicles. Although designed to guide a proposed NASA Entry Research Vehicle, the algorithm is sufficiently generic for a range of future entry vehicles. The plane change analysis provides insight suggesting a straight-forward algorithm based on an optimized nominal command profile. Bank angle, angle of attack, and engine thrust level, ignition and cutoff times are modulated to adjust the vehicle's trajectory to achieve the desired end-conditions. A performance evaluation of the scheme demonstrates a capability to guide to within 0.05 degrees of the desired plane change and five nautical miles of the desired apogee altitude while maintaining heating constraints. The algorithm is tested under off-nominal conditions of + or -30% density biases, two density profile models, + or -15% aerodynamic uncertainty, and a 33% thrust loss and for various combinations of these conditions.

Blissit, J. A.

1986-01-01

337

Isometric Immersions and Compensated Compactness  

NASA Astrophysics Data System (ADS)

A fundamental problem in differential geometry is to characterize intrinsic metrics on a two-dimensional Riemannian manifold {{mathcal M}^2} which can be realized as isometric immersions into {mathbb{R}^3}. This problem can be formulated as initial and/or boundary value problems for a system of nonlinear partial differential equations of mixed elliptic-hyperbolic type whose mathematical theory is largely incomplete. In this paper, we develop a general approach, which combines a fluid dynamic formulation of balance laws for the Gauss-Codazzi system with a compensated compactness framework, to deal with the initial and/or boundary value problems for isometric immersions in {mathbb{R}^3}. The compensated compactness framework formed here is a natural formulation to ensure the weak continuity of the Gauss-Codazzi system for approximate solutions, which yields the isometric realization of two-dimensional surfaces in {mathbb{R}^3}. As a first application of this approach, we study the isometric immersion problem for two-dimensional Riemannian manifolds with strictly negative Gauss curvature. We prove that there exists a C 1, 1 isometric immersion of the two-dimensional manifold in {mathbb{R}^3} satisfying our prescribed initial conditions. To achieve this, we introduce a vanishing viscosity method depending on the features of initial value problems for isometric immersions and present a technique to make the a priori estimates including the L ? control and H -1-compactness for the viscous approximate solutions. This yields the weak convergence of the vanishing viscosity approximate solutions and the weak continuity of the Gauss-Codazzi system for the approximate solutions, hence the existence of an isometric immersion of the manifold into {mathbb{R}^3} satisfying our initial conditions. The theory is applied to a specific example of the metric associated with the catenoid.

Chen, Gui-Qiang; Slemrod, Marshall; Wang, Dehua

2010-03-01

338

Compensating for synaptic loss in Alzheimer's disease.  

PubMed

Confirming that synaptic loss is directly related to cognitive deficit in Alzheimer's disease (AD) has been the focus of many studies. Compensation mechanisms counteract synaptic loss and prevent the catastrophic amnesia induced by synaptic loss via maintaining the activity levels of neural circuits. Here we investigate the interplay between various synaptic degeneration and compensation mechanisms, and abnormal cortical oscillations based on a large-scale network model consisting of 100,000 neurons exhibiting several cortical firing patterns, 8.5 million synapses, short-term plasticity, axonal delays and receptor kinetics. The structure of the model is inspired by the anatomy of the cerebral cortex. The results of the modelling study suggest that cortical oscillations respond differently to compensation mechanisms. Local compensation preserves the baseline activity of theta (5-7 Hz) and alpha (8-12 Hz) oscillations whereas delta (1-4 Hz) and beta (13-30 Hz) oscillations are maintained via global compensation. Applying compensation mechanisms independently shows greater effects than combining both compensation mechanisms in one model and applying them in parallel. Consequently, it can be speculated that enhancing local compensation might recover the neural processes and cognitive functions that are associated with theta and alpha oscillations whereas inducing global compensation might contribute to the repair of neural (cognitive) processes which are associated with delta and beta band activity. Compensation mechanisms may vary across cortical regions and the activation of inappropriate compensation mechanism in a particular region may fail to recover network dynamics and/or induce secondary pathological changes in the network. PMID:23728490

Abuhassan, Kamal; Coyle, Damien; Belatreche, Ammar; Maguire, Liam

2014-02-01

339

Atmospheric Thermodynamic Profiling with Neural Networks  

Microsoft Academic Search

This paper reviews recent progress in neural-network-based atmospheric parameter retrieval algorithms. Satellite-based observations of the atmosphere are related to atmospheric and surface variables by the radiative transfer equation. Direct inversion of the radiative transfer equation is often intractable as the underlying atmospheric phenomenology is usually neither linearly related to the observations nor Gaussian. Neural networks provide a computationally efficient alternative

Frederick W. Chen; William J. Blackwell

2007-01-01

340

Fatigue compensation during FES using surface EMG  

Microsoft Academic Search

Muscle fatigue limits the effectiveness of FES when applied to regain functional movements in spinal cord injured (SCI) individuals. The stimulation intensity must be manually increased to provide more force output to compensate for the decreasing muscle force due to fatigue. An artificial neural network (ANN) system was designed to compensate for muscle fatigue during functional electrical stimulation (FES) by

Jeffrey Winslow; Patrick L Jacobs; Dejan Tepavac; J. B. Wagenaar

2003-01-01

341

Motion Compensation Research Based on Motion Sensors  

Microsoft Academic Search

To attain high quality images, it is essential that very accurate motion compensation be applied to the radar returns to reduce image degradation, caused by spurious antenna center motion, to acceptable levels. A kind of high precision SINS\\/GPS integrated system for airborne SAR motion compensation is presented. This system, integrated the long-term stability of GPS (global positioning system) and the

Tan Gewei

2010-01-01

342

Compensation Basics For Managers and Supervisors  

E-print Network

;4 Truths About Compensation Truth #2: The best employees are not attracted, motivated and retained solely by money. Pay, benefits, attraction, career, & work/life motivation & retention #12;5 Truths About About Compensation Truth # 4: An employee's knowledge of base pay correlates highly with pay

Weaver, Harold A. "Hal"

343

Real-Time Adaptive Radiometric Compensation  

Microsoft Academic Search

Recent radiometric compensation techniques make it possible to project images onto colored and textured surfaces. This is realized with projector-camera systems by scanning the projection surface on a per-pixel basis. With the captured information, a compensation image is calculated that neutralizes geometric distortions and color blending caused by the underly- ing surface. As a result, the brightness and the contrast

Anselm Grundhfer; Oliver Bimber

2008-01-01

344

Tilt/Integral/Derivative Compensators For Controllers  

NASA Technical Reports Server (NTRS)

Tilt/integral/derivative (TID) compensators for tunable feedback control systems offer advantages over proportional/integral/derivative compensators. Designed and adjusted more easily, and made to reject disturbances more strongly and less sensitive to variations in parameters of controlled system.

Lurie, Boris J.

1995-01-01

345

Motion compensation for ISAR via centroid tracking  

Microsoft Academic Search

A compensation method of target radial motion is formulated and applied to obtain focused images in inverse synthetic aperture radar (ISAR). The basic scheme is to estimate the radial motion of the target centroid and to compensate in such a way that range and Doppler of the centroid are kept constant. Resultant images of X-band ISAR for ship and aircraft

T. Itoh; H. Sueda; Y. Watanabe

1996-01-01

346

Basic data for dosage calculation and compensation  

Microsoft Academic Search

Total body irradiation with megavoltage photon beams requires basic dosimetric data which have to be measured directly or derived from the standard data. This paper describes physical aspects of the technique involving 10 MV x-rays and bilateral opposing fields, and pays special attention to calibration, dose calculation and tissue compensation. Also discussed is a method for constructing individualized compensators for

Faiz M. Khan; Jeffrey F. Williamson; Wilfred Sewchand; Tae H. Kim

1980-01-01

347

Technological compensation circuit for accurate temperature sensor  

Microsoft Academic Search

A compensation circuit has been developed to reduce the VBE wafer spread of a bipolar transistor by taking advantage of the correlation between pinched base resistor RP and IS of the Ebers-Moll model. This compensation circuit was used in the design of a Celsius temperature sensor with intrinsic reference, improving its accuracy at least five times within the 0 C

R. Amador; A. Polanco; H. Hernndez; E. Gonzlez; A. Nagy

1998-01-01

348

Flexible specification of workflow compensation scopes  

Microsoft Academic Search

This paper addresses specification issues of that would be too expensive to implement as single ACID workflow process compensation. The main consideration is transactions. The idea was to implement such an application to reduce the numper of workflow activities that have to be as a saga or sequence of ACID transactions so that resources compensated and're-executed when a failure occurs,

Weimin Du; Jim Davis; Ming-Chien Shari

1997-01-01

349

77 FR 4885 - Patent Compensation Board Regulations  

Federal Register 2010, 2011, 2012, 2013

...serve as the Patent Compensation Board to hear and decide cases falling under the subject...addition, the Board has authority: (a) To hear and make decisions as to compensation under...Secrecy Act (35 U.S.C. 183); (b) to hear and make decisions as to whether a...

2012-02-01

350

Displacement Compensation of Temperature Probe Data  

NASA Technical Reports Server (NTRS)

Analysis of temperature data from a probe in a vertical Bridgman furnace growing germanium crystals revealed a displacement of the temperature profile due to conduction error. A theoretical analysis shows that the displacement compensation is independent of local temperature gradient. A displacement compensation value should become a standard characteristic of temperature probes used for temperature profile measurements.

Welch, Christopher S.; Hubert, James A.; Barber, Patrick G.

1996-01-01

351

Slip compensation for a Mars rover  

Microsoft Academic Search

A system that enables continuous slip compensation for a Mars rover has been designed, implemented, and field-tested. This system is composed of several components that allow the rover to accurately and continuously follow a designated path, compensate for slippage, and reach intended goals in high-slip environments. These components include: visual odometry, vehicle kinematics, a Kalman filter pose estimator, and a

Daniel M. Helmick; Yang Cheng; Daniel S. Clouse; Max Bajracharya; Larry H. Matthies; Stergios I. Roumeliotis

2005-01-01

352

Employer's Complete Guide to Unemployment Compensation.  

ERIC Educational Resources Information Center

This publication is a guide for employers who need specific information on unemployment compensation. Major topics discussed are an overview of the workings of the unemployment insurance system, the unemployment compensation amendments of 1976, receipt of claim notice, an employer's reaction to claims, student workers, faculty claims for summer

Madden, Matthew E.

353

Astigmatically compensated cavities for CW dye lasers  

Microsoft Academic Search

An analysis is given of folded 3-mirror laser resonators with an internal cell set at Brewster's angle. A method is described to compensate the astigmatic distortions introduced by both the internal mirror and the cell. This compensation is achieved for a specific relation between cell thickness and folding angle. It allows the formation of a tight intracavity focus as required

H. Kogelnik; E. Ippen; A. Dienes; C. Shank

1972-01-01

354

Compensating linkage for main rotor control  

NASA Technical Reports Server (NTRS)

A compensating linkage for the rotor control system on rotary wing aircraft is described. The main rotor and transmission are isolated from the airframe structure by clastic suspension. The compensating linkage prevents unwanted signal inputs to the rotor control system caused by relative motion of the airframe structure and the main rotor and transmission.

Jeffery, P. A. E.; Huber, R. F. (inventors)

1981-01-01

355

Disciplines Atmosphere  

E-print Network

#12;#12;Disciplines · Ecology · Atmosphere · Landscape · Geology · Hydrology · Oceanography · Study Agriculture Humidity NOAA Atmospheric Circulation Environment Urban planning Erosion Pedogenesis Morphogenesis

Laurini, Robert

356

The National Vaccine Injury Compensation Program.  

PubMed

The National Childhood Vaccine Injury Act of 1986 established the National Vaccine Injury Compensation Program to compensate people thought to be injured by certain vaccines. The act's goals are to ensure an adequate supply of vaccines, to stabilize vaccine costs, and to establish and maintain an accessible and efficient setting for providing compensation to people found to have been injured by certain childhood vaccines. In addition, the legislation called for the reporting of adverse events after vaccination, the creation of vaccine-information materials that detail vaccine benefits and risks, and Institute of Medicine studies of possible vaccine-related injuries and encouraged research and development of new and safer vaccines. Over its 22-year history, the National Vaccine Injury Compensation Program has been a key component in stabilizing the US vaccine market through liability protection to both vaccine companies and health care providers and by providing a forum for people, no matter what age, to seek compensation. PMID:21502255

Cook, Katherine M; Evans, Geoffrey

2011-05-01

357

The Atmosphere  

NSDL National Science Digital Library

This exercise is intended to reinforce the importance of Earth's atmosphere to living organisms. Topics include our bodies' interactions with the atmosphere; its composition and structure; and natural changes in the atmosphere (weather). Students will perform an actvity in which they are asked to observe and record weather conditions for four days, answer questions about their observations, and respond to a series of questions on general atmospheric characteristics. They will also learn how to convert temperature values from degrees Celsius to Fahrenheit.

Fox, Chris

358

Analysis and compensation of an aircraft simulator control loading system with compliant linkage. [using hydraulic equipment  

NASA Technical Reports Server (NTRS)

A hydraulic control loading system for aircraft simulation was analyzed to find the causes of undesirable low frequency oscillations and loading effects in the output. The hypothesis of mechanical compliance in the control linkage was substantiated by comparing the behavior of a mathematical model of the system with previously obtained experimental data. A compensation scheme based on the minimum integral of the squared difference between desired and actual output was shown to be effective in reducing the undesirable output effects. The structure of the proposed compensation was computed by use of a dynamic programing algorithm and a linear state space model of the fixed elements in the system.

Johnson, P. R.; Bardusch, R. E.

1974-01-01

359

An Algorithm to Detect the Presence of 3D Target Motion from ISAR Data  

Microsoft Academic Search

We present an algorithm to detect the presence of 3D target motion from ISAR data. Based on the 3D point scatterer model, we first examine the effect of 3D motion on ISAR imaging. It is shown that existing motion compensation algorithms cannot properly focus targets exhibiting 3D motion during the imaging interval. An algorithm is then derived to blindly detect

Junfei Li; Hao Ling; Victor Chen

2003-01-01

360

Interactive atmosphere  

NSDL National Science Digital Library

Where is ozone located in the atmosphere? This informational activity, part of an interactive laboratory series for grades 8-12, explores the changes in ozone concentration with altitude. Students are introduced to layers of the atmosphere and the amount of ozone found at each layer of the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The activity also discusses why the addition of ozone to the atmosphere at different levels determines the temperatures of those levels. Students can move up and down to different layers of the atmosphere. A temperature scale is shown that runs from the surface of the Earth to the outer most reaches of the atmosphere. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

361

New opportunities for secure communication networks using shaped femtosecond laser pulses inducing filamentation processes in the atmosphere  

NASA Astrophysics Data System (ADS)

The current study discusses new opportunities for secure ground to satellite communications using shaped femtosecond pulses that induce spatial hole burning in the atmosphere for efficient communications with data encoded within super-continua generated by femtosecond pulses. Refractive index variation across the different layers in the atmosphere may be modelled using assumptions that the upper strata of the atmosphere and troposphere behaving as layered composite amorphous dielectric networks composed of resistors and capacitors with different time constants across each layer. Input-output expressions of the dynamics of the networks in the frequency domain provide the transmission characteristics of the propagation medium. Femtosecond pulse shaping may be used to optimize the pulse phase-front and spectral composition across the different layers in the atmosphere. A generic procedure based on evolutionary algorithms to perform the pulse shaping is proposed. In contrast to alternative procedures that would require ab initio modelling and calculations of the propagation constant for the pulse through the atmosphere, the proposed approach is adaptive, compensating for refractive index variations along the column of air between the transmitter and receiver.

Alyami, H. M.; Becerra, V. M.; Hadjiloucas, S.

2013-11-01

362

Atmospheric gases  

NSDL National Science Digital Library

Which gases make up the atmosphere? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the gaseous components of the atmosphere. Students explore the main gases of the atmosphere using a pop-up pie chart. Descriptions of the gases and their percentages in the atmosphere are provided. Students read about water vapor in the atmosphere, and an animation shows a simplified process of precipitation. A pop-up window explains the effects of dust on the atmosphere, and a photograph shows how large amounts of dust in the atmosphere create the reds and oranges displayed in sunsets. Finally, ozone is introduced to students as a necessary component of human life on Earth. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

363

10 CFR 39.53 - Energy compensation source.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Energy compensation source. 39.53 Section 39.53...LOGGING Equipment 39.53 Energy compensation source. The licensee may use an energy compensation source (ECS) which is...

2010-01-01

364

48 CFR 970.2803-1 - Workers' Compensation Insurance.  

Code of Federal Regulations, 2010 CFR

...requirements. Certain workers' compensation laws...The policy with respect to these limitations...contractors purchase workers' compensation insurance. With respect to self-insured...primary or excess workers' compensation and...

2010-10-01

365

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

Code of Federal Regulations, 2012 CFR

...FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.316 Subsequent incarceration of compensation recipient. If a claimant, who...

2012-07-01

366

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

Code of Federal Regulations, 2013 CFR

...FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.316 Subsequent incarceration of compensation recipient. If a claimant, who...

2013-07-01

367

28 CFR 301.318 - Civilian compensation laws distinguished.  

Code of Federal Regulations, 2011 CFR

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.318 Civilian compensation...receives wages while absent from work. Other factors necessarily...who allege they have sustained work-related injuries, the...

2011-07-01

368

28 CFR 301.318 - Civilian compensation laws distinguished.  

Code of Federal Regulations, 2013 CFR

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.318 Civilian compensation...receives wages while absent from work. Other factors necessarily...who allege they have sustained work-related injuries, the...

2013-07-01

369

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

...FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.316 Subsequent incarceration of compensation recipient. If a claimant, who...

2014-07-01

370

28 CFR 301.318 - Civilian compensation laws distinguished.  

Code of Federal Regulations, 2010 CFR

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.318 Civilian compensation...receives wages while absent from work. Other factors necessarily...who allege they have sustained work-related injuries, the...

2010-07-01

371

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

Code of Federal Regulations, 2011 CFR

...FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.316 Subsequent incarceration of compensation recipient. If a claimant, who...

2011-07-01

372

28 CFR 301.318 - Civilian compensation laws distinguished.  

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.318 Civilian compensation...receives wages while absent from work. Other factors necessarily...who allege they have sustained work-related injuries, the...

2014-07-01

373

28 CFR 301.318 - Civilian compensation laws distinguished.  

Code of Federal Regulations, 2012 CFR

...COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.318 Civilian compensation...receives wages while absent from work. Other factors necessarily...who allege they have sustained work-related injuries, the...

2012-07-01

374

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

Code of Federal Regulations, 2010 CFR

...FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.316 Subsequent incarceration of compensation recipient. If a claimant, who...

2010-07-01

375

31 CFR 30.0 - Executive compensation and corporate governance.  

Code of Federal Regulations, 2010 CFR

...Executive compensation and corporate governance. 30.0 Section 30.0 Money...STANDARDS FOR COMPENSATION AND CORPORATE GOVERNANCE 30.0 Executive compensation and corporate governance. The following questions and...

2010-07-01

376

Visual algorithms  

SciTech Connect

Nonlinear, local and highly parallel algorithms can perform several simple but important visual computations. Specific classes of algorithms can be considered in an abstract way. The author here the class of polynomial algorithms to exemplify some of the important issues for visual processing like linear vs. nonlinear and local vs. global. Polynomial algorithms are a natural extension of Perceptrons to time dependent grey level images. Although they share most of the limitations of Perceptrons, they are powerful parallel computational devices. Several of their properties are characterized and especially their equivalence with Perceptrons for geometrical figures and the synthesis of nonlinear algorithms(mapping) via associative learning. Finally, the paper considers how algorithms of this type could be implemented in nervous hardware, in terms of synaptic interactions strategically located in a dendritic tree. The implementation of three specific algorithms is briefly outlined: direction sensitive motion detection; detection of discontinuities in the optical flow; and detection and localization of zero-crossings in the convolution of the image with the Laplacian (of a Gaussian). In the appendix, another (nonlinear) differential operator, the second directional derivative along the gradient, is briefly discussed as an alternative to the Laplacian.

Lozano-Perez, T.

1982-05-01

377

Algorithms: Greedy Algorithms Amotz Bar-Noy  

E-print Network

Algorithms: Greedy Algorithms Amotz Bar-Noy CUNY Spring 2012 Amotz Bar-Noy (CUNY) Greedy Algorithms Spring 2012 1 / 62 #12;Greedy Algorithms Greedy algorithms make decisions that "seem" to be the best) Greedy Algorithms Spring 2012 2 / 62 #12;How and When to use Greedy Algorithms? Initial solution

Bar-Noy, Amotz

378

Spectral response compensation for photon-counting clinical x-ray CT using sinogram restoration  

NASA Astrophysics Data System (ADS)

The x-ray spectrum recorded by a photon-counting x-ray detector (PCXD) is distorted due to the following physical effects which are independent of the count rate: finite energy-resolution, Compton scattering, charge-sharing, and Kescape. If left uncompensated, the spectral response (SR) of a PCXD due to the above effects will result in image artifacts and inaccurate material decomposition. We propose a new SR compensation (SRC) algorithm using the sinogram restoration approach. The two main contributions of our proposed algorithm are: (1) our algorithm uses an efficient conjugate gradient method in which the first and second derivatives of the cost functions are directly calculated analytically, whereas a slower optimization method that requires numerous function evaluations was used in other work; (2) our algorithm guarantees convergence by combining the non-linear conjugate gradient method with line searches that satisfy Wolfe conditions, whereas the algorithm in other work is not backed by theorems from optimization theory to guarantee convergence. In this study, we validate the performance of the proposed algorithm using computer simulations. The bias was reduced to zero from 11%, and image artifacts were removed from the reconstructed images. Quantitative K-edge imaging in possible only when SR compensation is done.

Srivastava, Somesh; Cammin, Jochen; Fung, George S. K.; Tsui, Benjamin M. W.; Taguchi, Katsuyuki

2012-03-01

379

The research of wavefront compensation of a reflective beam shaping system  

NASA Astrophysics Data System (ADS)

In order to compensate the low order aberrations effectively and rapidly, a new method is developed to study the wavefront compensation of a reflective beam shaping system by using simulation experiments. The system consists of three cylinder mirrors and a spherical mirror. By inserting different Zernike phase screens, many sizes and species of low order aberrations can be simulated. Then the data communication is set up between Matlab and Zemax based on dynamic data exchange (DDE) technique. The configuration parameters of the system constructed by Zemax could be regarded as variables, and the beam shaping system as the transfer function, overall appropriate optimization algorithm was utilized to solve the optimal configuration to make the compensation system most effective.

Gu, Dianyu; Liu, Wenguang; Zhou, Qiong

2013-09-01

380

Study on imaging algorithm of missile-borne MMW SAR for ground target  

Microsoft Academic Search

In this paper, in light of the imaging characteristics of missile-borne MMW spotlight SAR for ground target, some main problems including the imaging resolution and choice of pulse repetition frequency are discussed. Then a new scheme of motion compensation which consists of range alignment, phase adjustment and compensation for the movement with non-constant velocity is presented. Image reconstruction algorithm by

Wenchong Xie; Wenfeng Sun; Yongliang Wang

2003-01-01

381

An automatic stain removal algorithm of series aerial photograph based on flat-field correction  

Microsoft Academic Search

The dust on the camera's lens will leave dark stains on the image. Calibrating and compensating the intensity of the stained pixels play an important role in the airborne image processing. This article introduces an automatic compensation algorithm for the dark stains. It's based on the theory of flat-field correction. We produced a whiteboard reference image by aggregating hundreds of

Gang Wang; Dongmei Yan; Yang Yang

2010-01-01

382

Algorithmic embeddings  

E-print Network

We present several computationally efficient algorithms, and complexity results on low distortion mappings between metric spaces. An embedding between two metric spaces is a mapping between the two metric spaces and the ...

B?doiu, Mihai, 1978-

2006-01-01

383

Algorithms, Theory  

E-print Network

Ant robots have very low computational power and limited memory. They communicate by leaving pheromones in the environment. In order to create a cooperative intelligent behavior, ants may need to get together; however, they may not know the locations of other ants. Hence, we focus on an ant variant of the rendezvous problem, in which two ants are to be brought to the same location in finite time. We introduce two algorithms that solve this problem for two ants by simulating a bidirectional search in different environment settings. An algorithm for an environment with no obstacles and a general algorithm that handles all types of obstacles. We provide detailed discussion on the different attributes, size of pheromone required, and the performance of these algorithms.

Asaf Shiloni; Alon Levy; Ariel Felner; Meir Kalech

384

?f Algorithm  

NASA Astrophysics Data System (ADS)

The ?f Algorithm is a low noise particle code algorithm. The perturbation of the distribution function ( ?f) away from a large equilibrium is evolved rather than the total distribution function. "Particles" in the code are actually Lagrangian markers at which the value of the distribution function is known, The magnitude of the numerical noise is characteristic of the size of the perturbation rather than the equilibrium and scales roughly as the inverse of the number of particles, In this paper, the algorithm is described, and conserved energies are derived for linear and nonlinear sets of equations. Two different forms of the energy principle test separately adequate resolution in time and space and adequacy of the number of simulation particles. A semi-implicit time step method is described which allows violation of the Courant condition. Low noise capabilities of a linear code using the algorithm are demonstrated.

Denton, Richard E.; Kotschenreuther, M.

1995-07-01

385

Strategic algorithms  

E-print Network

Classical algorithms from theoretical computer science arise time and again in practice. However,a practical situations typically do not fit precisely into the traditional theoretical models. Additional necessary components ...

Nikolova, Evdokia Velinova

2009-01-01

386

The Atmosphere  

Microsoft Academic Search

\\u000a The atmosphere is closely related to hydrology in a fundamental manner. It will, therefore, be appropriate to make a brief\\u000a introduction to the subject of atmosphere. As pointed out in chapter 1, atmosphere is a thin shell of gases, which is held\\u000a close to the earth by the gravitational attraction and is commonly called the air. These gases seem to

Pukh Raj Rakhecha; Vijay P. Singh

387

Pluripotent cells will not dosage compensate  

PubMed Central

Dosage compensation is the mechanism that balances gene expression levels between males and females as well as between the X chromosome and autosomes. In mammals, loss of pluripotency and differentiation are closely linked with the onset of dosage compensation. Pluripotency factors negatively regulate Xist (the non-coding RNA that triggers X chromosome inactivation) and positively regulate Tsix, a repressor of Xist, to inhibit dosage compensation. In addition, X chromosome dose also regulates exit from the pluripotent state. A double dose of X chromosomes in undifferentiated female cells inhibits the MAPK and Gsk3 signaling pathways and activates the Akt pathway, thereby blocking differentiation. Here we review our recent report, which showed that the onset of dosage compensation is also linked to the loss of pluripotency in C. elegans. We discuss these findings in light of what is known about pluripotency and differentiation in this organism.

Jiang, Jianhao; Lau, Alyssa C; Csankovszki, Gyorgyi

2014-01-01

388

33 CFR 136.205 - Compensation allowable.  

...Section 136.205 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF...

2014-07-01

389

33 CFR 136.211 - Compensation allowable.  

...Section 136.211 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF...

2014-07-01

390

77 FR 5381 - Plum Pox Compensation  

Federal Register 2010, 2011, 2012, 2013

...eligible owners of non-fruit-bearing ornamental tree nurseries and to increase the amount of compensation...owners of commercial stone fruit orchards and fruit tree nurseries whose trees are required to be destroyed in order to prevent...

2012-02-03

391

77 FR 58469 - Plum Pox Compensation  

Federal Register 2010, 2011, 2012, 2013

...eligible owners of non-fruit-bearing ornamental tree nurseries and to increase the amount of compensation...owners of commercial stone fruit orchards and fruit tree nurseries whose trees are required to be destroyed in order to prevent...

2012-09-21

392

GENDER EQUITY ASSESSMENT: Faculty Compensation and Headcounts  

E-print Network

GENDER EQUITY ASSESSMENT: Faculty Compensation and Headcounts May 2013 #12; 2 | P a g e CONTENTS GENDER EQUITY IN THE COLLEGE OF LIBERAL ARTS ..................................................................................................... 4 Figure 1: Academic Rate by Gender for Full Professors

Texas at Austin, University of

393

Spike Timing Dependent Adaptation for Mismatch Compensation  

E-print Network

Spike Timing Dependent Adaptation for Mismatch Compensation Katherine Cameron, Alan Murray School of Engineering and Electronics The University of Edinburgh Edinburgh, EH9 3JL, UK Email: k.cameron@ed.ac.uk, alan

Cameron, Katherine

394

CEO compensation: a question of ethics  

E-print Network

The outrageous corporate accounting and fraud scandals in the past years have all but demolished investors' faith in our accounting framework. One big area of concern is executive compensation. In 1992, Congress enacted section 162(m...

Cole, James Harrison

2013-02-22

395

14 CFR 158.53 - Collection compensation.  

Code of Federal Regulations, 2010 CFR

...provided under paragraph (c)(1) of this section, if the data is submitted by carriers representing at least 75 percent of PFCs collected nationwide. (3) Any new compensation level determined by the FAA under paragraph (c)(2) of this...

2010-01-01

396

Temperature compensated two-mode fiber interferometer  

E-print Network

In this thesis we propose an innovative approach of designing and implementing a temperature compensated two-mode optical fiber interferometer in a control system of stabilizing the wavelength of a laser. We give the procedure for designing...

Doma, Jagdish Ramchandra

2012-06-07

397

Attitudes of California Dermatologists Toward Worker's Compensation  

PubMed Central

A survey-questionnaire on Worker's Compensation sent to 492 California dermatologists produced 268 replies, a recovery rate of 54 percent, representing approximately 10 percent of the practicing dermatologists in the United States. A total of 75 percent replied they treat Worker's Compensation patients; most of the 25 percent who replied they do not gave strong reasons for refusing to assume the care of these patients. The answers to the questionnaire given by the 201 California dermatologists who treat Worker's Compensation patients are tabulated and discussed. Although there exists considerable misunderstanding among physicians, insurance companies and employers on many aspects of Worker's Compensation, the situation is not without hope for improvement. Better knowledge of work procedures, more availability of precise information on the ingredients of work contactants and cooperation among the interested parties should improve the quality of care for these patients in the future. PMID:135417

Adams, Robert M.

1976-01-01

398

Compensating for estimation smoothing in kriging  

USGS Publications Warehouse

Smoothing is a characteristic inherent to all minimum mean-square-error spatial estimators such as kriging. Cross-validation can be used to detect and model such smoothing. Inversion of the model produces a new estimator-compensated kriging. A numerical comparison based on an exhaustive permeability sampling of a 4-fr2 slab of Berea Sandstone shows that the estimation surface generated by compensated kriging has properties intermediate between those generated by ordinary kriging and stochastic realizations resulting from simulated annealing and sequential Gaussian simulation. The frequency distribution is well reproduced by the compensated kriging surface, which also approximates the experimental semivariogram well - better than ordinary kriging, but not as well as stochastic realizations. Compensated kriging produces surfaces that are more accurate than stochastic realizations, but not as accurate as ordinary kriging. ?? 1996 International Association for Mathematical Geology.

Olea, R.A.; Pawlowsky, Vera

1996-01-01

399

Cluster algorithms  

E-print Network

Cluster algorithms for classical and quantum spin systems are discussed. In particular, the cluster algorithm is applied to classical O(N) lattice actions containing interactions of more than two spins. The performance of the multi-cluster and single--cluster methods, and of the standard and improved estimators are compared. (Lecture given at the summer school on `Advances in Computer Simulations', Budapest, July 1996.)

Ferenc Niedermayer

1997-04-21

400

Nonlinear Thermal Compensators for WGM Resonators  

NASA Technical Reports Server (NTRS)

In an alternative version of a proposed bimaterial thermal compensator for a whispering-gallery-mode (WGM) optical resonator, a mechanical element having nonlinear stiffness would be added to enable stabilization of a desired resonance frequency at a suitable fixed working temperature. The previous version was described in "Bimaterial Thermal Compensators for WGM Resonators." Both versions are intended to serve as inexpensive means of preventing (to first order) or reducing temperature-related changes in resonance frequencies.

Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry; Maleki, Lute; Yu, Nan; Iltchenko, Vladimir

2009-01-01

401

Beyond negligence: avoidability and medical injury compensation.  

PubMed

Disenchantment with the tort system and negligence standard in the United States is fueling interest in alternate compensation systems for medical injury. One possibility is experimentation with administrative "health courts," through which specialized adjudicators would utilize neutral experts to render compensability determinations. Compensation would be based not on negligence, but rather on a broader avoidable medical injury (avoidability) standard. Although considerable interest in health courts exists, stakeholders frequently express uncertainty about the meaning and operation of an avoidability standard. Three nations-Sweden, Denmark, and New Zealand-have long operated administrative schemes. We conducted interviews with administrators and stakeholders in these systems. Our goal was to garner lessons on how to operate a health court, and specifically, how to develop and apply alternate compensation criteria such as avoidability. This article reports our findings on the origins and operations of the systems, the evolution of their compensation criteria, and how these criteria are actually applied. We found that all three systems had their primary genesis in ensuring compensation for the injured, as opposed to sanctioning providers. All have abandoned the negligence standard. The Nordic systems use an avoidability standard, principally defined as injury that would not occur in the hands of the best practitioner. Their experience demonstrates that this definition is feasible to apply. New Zealand's recent move to a no-fault system sheds light on the benefits and drawbacks of a variety of compensation standards. Key lessons for successfully applying an alternate standard, such as avoidability, include a strict adherence to national precedent, the use of neutral and experienced experts, and a block on routine transfer of information from compensation investigations to disciplinary authorities. Importantly, all three nations are harnessing their systems' power to improve patient safety, and the avoidability standard appears to be well suited for this task. PMID:17931762

Kachalia, Allen B; Mello, Michelle M; Brennan, Troyen A; Studdert, David M

2008-01-01

402

Prostate implant reconstruction from C-arm images with motion-compensated tomosynthesis  

SciTech Connect

Purpose: Accurate localization of prostate implants from several C-arm images is necessary for ultrasound-fluoroscopy fusion and intraoperative dosimetry. The authors propose a computational motion compensation method for tomosynthesis-based reconstruction that enables 3D localization of prostate implants from C-arm images despite C-arm oscillation and sagging. Methods: Five C-arm images are captured by rotating the C-arm around its primary axis, while measuring its rotation angle using a protractor or the C-arm joint encoder. The C-arm images are processed to obtain binary seed-only images from which a volume of interest is reconstructed. The motion compensation algorithm, iteratively, compensates for 2D translational motion of the C-arm by maximizing the number of voxels that project on a seed projection in all of the images. This obviates the need for C-arm full pose tracking traditionally implemented using radio-opaque fiducials or external trackers. The proposed reconstruction method is tested in simulations, in a phantom study and on ten patient data sets. Results: In a phantom implanted with 136 dummy seeds, the seed detection rate was 100% with a localization error of 0.86 {+-} 0.44 mm (Mean {+-} STD) compared to CT. For patient data sets, a detection rate of 99.5% was achieved in approximately 1 min per patient. The reconstruction results for patient data sets were compared against an available matching-based reconstruction method and showed relative localization difference of 0.5 {+-} 0.4 mm. Conclusions: The motion compensation method can successfully compensate for large C-arm motion without using radio-opaque fiducial or external trackers. Considering the efficacy of the algorithm, its successful reconstruction rate and low computational burden, the algorithm is feasible for clinical use.

Dehghan, Ehsan; Moradi, Mehdi; Wen, Xu; French, Danny; Lobo, Julio; Morris, W. James; Salcudean, Septimiu E.; Fichtinger, Gabor [School of Computing, Queen's University, Kingston, Ontario K7L-3N6 (Canada); Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia V6T-1Z4 (Canada); Vancouver Cancer Centre, Vancouver, British Columbia V5Z-1E6 (Canada); Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia V6T-1Z4 (Canada); School of Computing, Queen's University, Kingston, Ontario K7L-3N6 (Canada)

2011-10-15

403

Prostate implant reconstruction from C-arm images with motion-compensated tomosynthesis  

PubMed Central

Purpose: Accurate localization of prostate implants from several C-arm images is necessary for ultrasound-fluoroscopy fusion and intraoperative dosimetry. The authors propose a computational motion compensation method for tomosynthesis-based reconstruction that enables 3D localization of prostate implants from C-arm images despite C-arm oscillation and sagging. Methods: Five C-arm images are captured by rotating the C-arm around its primary axis, while measuring its rotation angle using a protractor or the C-arm joint encoder. The C-arm images are processed to obtain binary seed-only images from which a volume of interest is reconstructed. The motion compensation algorithm, iteratively, compensates for 2D translational motion of the C-arm by maximizing the number of voxels that project on a seed projection in all of the images. This obviates the need for C-arm full pose tracking traditionally implemented using radio-opaque fiducials or external trackers. The proposed reconstruction method is tested in simulations, in a phantom study and on ten patient data sets. Results: In a phantom implanted with 136 dummy seeds, the seed detection rate was 100% with a localization error of 0.86??0.44 mm (Mean??STD) compared to CT. For patient data sets, a detection rate of 99.5% was achieved in approximately 1 min per patient. The reconstruction results for patient data sets were compared against an available matching-based reconstruction method and showed relative localization difference of 0.5??0.4 mm. Conclusions: The motion compensation method can successfully compensate for large C-arm motion without using radio-opaque fiducial or external trackers. Considering the efficacy of the algorithm, its successful reconstruction rate and low computational burden, the algorithm is feasible for clinical use. PMID:21992346

Dehghan, Ehsan; Moradi, Mehdi; Wen, Xu; French, Danny; Lobo, Julio; Morris, W. James; Salcudean, Septimiu E.; Fichtinger, Gabor

2011-01-01

404

Decorrelation control by the cerebellum achieves oculomotor plant compensation in simulated vestibulo-ocular reflex.  

PubMed

We introduce decorrelation control as a candidate algorithm for the cerebellar microcircuit and demonstrate its utility for oculomotor plant compensation in a linear model of the vestibulo-ocular reflex (VOR). Using an adaptive-filter representation of cerebellar cortex and an anti-Hebbian learning rule, the algorithm learnt to compensate for the oculomotor plant by minimizing correlations between a predictor variable (eye-movement command) and a target variable (retinal slip), without requiring a motor-error signal. Because it also provides an estimate of the unpredicted component of the target variable, decorrelation control can simplify both motor coordination and sensory acquisition. It thus unifies motor and sensory cerebellar functions. PMID:12350251

Dean, Paul; Porrill, John; Stone, James V

2002-09-22

405

Decorrelation control by the cerebellum achieves oculomotor plant compensation in simulated vestibulo-ocular reflex.  

PubMed Central

We introduce decorrelation control as a candidate algorithm for the cerebellar microcircuit and demonstrate its utility for oculomotor plant compensation in a linear model of the vestibulo-ocular reflex (VOR). Using an adaptive-filter representation of cerebellar cortex and an anti-Hebbian learning rule, the algorithm learnt to compensate for the oculomotor plant by minimizing correlations between a predictor variable (eye-movement command) and a target variable (retinal slip), without requiring a motor-error signal. Because it also provides an estimate of the unpredicted component of the target variable, decorrelation control can simplify both motor coordination and sensory acquisition. It thus unifies motor and sensory cerebellar functions. PMID:12350251

Dean, Paul; Porrill, John; Stone, James V

2002-01-01

406

Computer-assisted electropneumatic system to compensate for the sag of an optoelectronic detector  

NASA Astrophysics Data System (ADS)

This paper presents an electropneumatical system computer assisted for compensate the sag of an optoelectronical detector. This system is used for compensate the sag of a frame of an optoelectronical detector during the fabrication. For push-up group we use pneumatically servocylinders which allowed a very precise control of the sag through force. Each servo cylinder includes a proportional pressure regulator for regulating the pressure proportional to a specified electrical nominal value. The system is controlling by a PC with 2 acquisition board, one of them for monitoring the force of the transducer and the other board for controlling the pressure of the gas in servo cylinders. The software subsystem for developing the tuning numerical algorithm contents WIN 98 operating system, TestPoint rapid application development platform for data acquisition and graphic user software and Delphi rapid application developing platform for real time control algorithm module.

Blejan, Marian; Drumea, Petrin; Enache, Ioana; Marin, Mihai; Comanescu, Brindus; Oancea, Daniel

2000-02-01

407

High-power 355 nm third-harmonic generation with effective walk-off compensation of LBO  

NASA Astrophysics Data System (ADS)

Walk-off compensation using wedged cut type-II LBO was investigated theoretically and experimentally. An algorithm is proposed to find the optimized wedged cut angle to compensate the walk-off effect completely. Using a pulsed Nd:Y V O4 MOPA laser as the fundamental frequency infrared (IR) source, 36.3 W 355 nm frequency converted ultraviolet (UV) light was obtained using an optimized wedged cut type-II LBO for walk-off compensated third-harmonic generation (THG), giving a conversion efficiency of 37.1% from IR to UV. A comparative experiment using a conventional cut type-II LBO was also implemented. The results indicate that optimized wedged cutting of type-II LBO is an effective approach for walk-off compensation in efficient THG. The output performance of angle and temperature tuning for wedged cut type-II LBO was also investigated.

Yan, Xingpeng; Liu, Qiang; Pei, Chuang; Wang, Dongsheng; Gong, Mali

2014-04-01

408

Atmospheric chemistry  

SciTech Connect

This book covers the predictive strength of atmospheric models. The book covers all of the major important atmospheric areas, including large scale models for ozone depletion and global warming, regional scale models for urban smog (ozone and visibility impairment) and acid rain, as well as accompanying models of cloud processes and biofeedbacks.

Sloane, C.S. (General Motors Research Labs., Warren, MI (United States)); Tesche, T.W. (Alpine Geophysics (US))

1991-01-01

409

PMD compensation and mitigation with new modulation formats in WDM System  

NASA Astrophysics Data System (ADS)

We study the polarization-mode dispersion (PMD) compensation and mitigation performance, using a single PMD compensator to compensate several channels at the same time with degree of polarization (DOP) as the feedback signal in a 2 40 / Gb s WDM system. Particle-swarm optimization (PSO) algorithm is used to search and track the dynamic degree of polarization (DOP) to achieve the adaptive PMD compensation. New modulation formats are used to mitigate PMD, and the dynamic combination of PMD mitigation taking CSRZDPSK and CSRZDQPSK as the advanced modulation formats have been successfully completed. The numerical results show that the differential phase-shift keyed (DPSK) and differential quadrature phase shift keying (DQPSK) modulation formats are more suitable for PMD mitigation system than the on-off keying (OOK) modulation format. Furthermore, DQPSK format can simultaneously double WDM spectrum-packing efficiency and upgrade the system capacity while it can still has the same mitigation performance as the DPSK format in the PMD compensation system. These features make them greatly attractive for high-speed long-haul WDM system.

Lu, Ping; Zhang, Xiaoguang; Jiang, Daya

2008-11-01

410

Improved disturbance rejection with online adaptive pole-zero compensation on a ?-shaped PZT active suspension  

Microsoft Academic Search

In feedback control systems, the anti-resonant zeros cannot be arbitrarily placed, hence degrading tracking performance as\\u000a well as input disturbance and noise rejection capabilities due to reduced gain at the frequencies of the zeros. In this paper,\\u000a an online adaptive inverse control with saturation (OAICS) algorithm is proposed for compensating the minimum phase resonant\\u000a poles and anti-resonant zeros of a

Chee Khiang Pang; Sai Cheong Tam; Guoxiao Guo; Ben M. Chen; Frank L. Lewis; Tong Heng Lee; Chunling Du

2009-01-01

411

Net-Shape Forging of Aerofoil Blade based on Flash Trimming and Compensation methods  

SciTech Connect

In this research, an automatic blade forging die shape optimisation system was developed by using direct compensation and flash trimming algorithms and integrating with the DEFORM 3D software package. To validate the developed system, a 3D blade forging case problem was simulated and optimised with and without the consideration of trimming simulation. The results were compared with actual measurement data of the forged aerofoil blade with excellent results obtained with the fast trimming simulation procedure used.

Lu, B. [Department of Plasticity Forming Engineering, Shanghai Jiao Tong University, Shanghai, 200030 (China); Ou, H. [Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Nottingham, NG7 2RD (United Kingdom); Armstrong, C. G. [School of Mechanical and Aerospace Engineering, Queen's University Belfast, Belfast, BT9 5AH (United Kingdom)

2011-05-04

412

IC for motion-compensated 100 Hz TV with natural-motion movie-mode  

Microsoft Academic Search

An IC for consumer 100 Hz television has been designed and is described in this paper. It applies motion estimation and compensation algorithms for high-quality field rate upconversion and a judder-free motion portrayal of movie material. Noise reduction and vertical zoom are also included on-chip. The IC processes luminance as well as chrominance, and automatically adapts to movie-material. A new

G. de Haan; J. Kettenis; A. Loning; B. De Loore

1996-01-01

413

Combined system for the compensation of the solar pressure-induced disturbing torque for geostationary satellites  

NASA Astrophysics Data System (ADS)

The problem is considered of determining the shape and dimensions of the passive component in a combined system for offsetting the solar pressure-induced disturbing torque for geostationary spacecraft with asymmetrical solar arrays. The problem statement, numerical solution algorithm, and calculated results are presented. The resulting shape, the study suggests, not only has the required compensation properties but is also the most efficient from the standpoint of manufacture and functional reliability.

Shmatov, S. I.; Mordvinkin, A. S.

2014-12-01

414

DSP-based compensation of non-linear impairments in 100 Gb\\/s PolMux QPSK  

Microsoft Academic Search

PolMux QPSK has emerged as the solution of choice for the first commercial implementations of 100 Gb\\/s transmission systems. Thanks to coherent detection and digital signal processing (DSP), linear distortions such as chromatic dispersion (CD) and polarisation mode dispersion (PMD) can in principle be completely compensated for. And indeed, effective algorithms have been devised and extensively investigate that allow CD-

Marco Mussolin; Marco Forzati; J. Martensson; A. Carena; G. Bosco

2010-01-01

415

Compensation for 3D physiological motion in robotic-assisted surgery using a predictive force controller. Experimental results  

Microsoft Academic Search

This paper presents a predictive force control approach to compensate for the physiological motion induced by both respiratory and heart beating motions during cardiac surgery. It focuses on the design and implementation of the control algorithm in the context of robotized minimally invasive surgery. The controller is based on a linear predictive control loop using the force information applied on

Michel Dominici; Philippe Poignet; Rui Corteso; Etienne Dombre; Olivier Tempier

2009-01-01

416

UCF Re-employment Compensation Process Background Information  

E-print Network

1 UCF Re-employment Compensation Process Background Information: Re-employment compensation position. Re-employment compensation is a federal-state partnership based upon federal law but it is administered at the state level. Re-employment compensation is a temporary, partial wage replacement

Wu, Shin-Tson

417

Mergers and Acquisitions: How Executive Compensation May Affect Deal  

Microsoft Academic Search

Mergers and acquisitions almost always threaten a corporation's existing compensation plan. When such transactions occur, the acquiring company must consider and evaluate the acquired company's current executive compensation program. In addition, it must measure the value of the acquired company's compensation components, implement its own policies, and restructure a new executive compensation program. Some of the issues executives will want

Lawrence C. Bickford

1997-01-01

418

Friction Problems in Servomechanisms: Modeling and Compensation Techniques  

E-print Network

Friction Problems in Servomechanisms: Modeling and Compensation Techniques Jan Tommy Gravdahl of this presentation Introduction Friction models 1. Static models 2. Models with time delay 3. Dynamic models Friction compensation 1. Non-model based compensation 2. Compensation based on static friction models 3

Gravdahl, Jan Tommy

419

Greedy Algorithms and Matroids  

E-print Network

Greedy Algorithms and Matroids Andreas Klappenecker #12;Greedy Algorithms A greedy algorithm solves of algorithms. #12;Correct Greedy Algorithms When a greedy algorithm terminates, then the hope is always reached, then the algorithm is correct. #12;Properties A greedy algorithm successively solves

Klappenecker, Andreas

420

Compensation method for random drifts of laser beams based on moving average feedback control  

NASA Astrophysics Data System (ADS)

In order to eliminate the measurement errors caused by the instability of laser beams, a real-time compensation algorithms for the random drifts of laser beams based on moving average (MA) correction mechanism was presented. By establishing a correction model with two fast steering mirrors in the beam delivery path and analyzing the pulse to pulse beam fluctuation, a real-time beam drifts correction is implemented based on closed loop feedback control, which especially focuses on reducing the pulse to pulse drifts and ground fluctuations. The simulation results show that this algorithm can control beam drifts effectively. Optimal MA can be reduced to 3n-1/2 times (n--pulse numbers in a window) without the ground vibrations. There are a series of improvements on the moving standard deviation (MSD) as well. MSD get a sudden decline at the window pulse. Meanwhile, the drifts can be restrained while loading the ground vibrations without any big jump, and the dropping amplitude is bigger than without the ground vibration. MSD drop while the whole system is controlled by this compensation method and the results are stable. The key of this compensation method for random drifts of laser beams based on moving average feedback control lies in the appropriate corrections formula. What is more, this algorithm which is practical can achieve high precision control of direction drifts.

Zhang, Lixia; Wang, Ruilin; Lin, Wumei; Liao, Zhijie

2012-10-01

421

Algorithmic alternatives  

SciTech Connect

A large variety of Monte Carlo algorithms are being used for lattice gauge simulations. For purely bosonic theories, present approaches are generally adequate; nevertheless, overrelaxation techniques promise savings by a factor of about three in computer time. For fermionic fields the situation is more difficult and less clear. Algorithms which involve an extrapolation to a vanishing step size are all quite closely related. Methods which do not require such an approximation tend to require computer time which grows as the square of the volume of the system. Recent developments combining global accept/reject stages with Langevin or microcanonical updatings promise to reduce this growth to V/sup 4/3/.

Creutz, M.

1987-11-01

422

An efficient gray search algorithm for the estimation of motion vectors  

Microsoft Academic Search

Motion vector estimation plays an important role in motion-compensated video coding. An efficient and fast search algorithm is proposed for the estimation of motion vectors. With the help of gray prediction, the algorithm can determine the motion vectors of image blocks quickly and correctly. Since the proposed algorithm performs better than other search algorithms [e.g. the three-step search (TSS), cross-search

Jau-Ling Chen; Pei-Yin Chen

2001-01-01

423

A Modified EMD Algorithm and its Applications  

E-print Network

The classical EMD algorithm has been used extensively in the literature to decompose signals that contain nonlinear waves. However when a signal contain two or more frequencies that are close to one another the decomposition might fail. In this paper we propose a new formulation of this algorithm which is based on the zero crossings of the signal and show that it performs well even when the classical algorithm fail. We address also the filtering properties and convergence rate of the new algorithm versus the classical EMD algorithm. These properties are compared then to those of the principal component algorithm (PCA). Finally we apply this algorithm to the detection of gravity waves in the atmosphere.

Humi, Mayer

2011-01-01

424

20 CFR 25.101 - How is compensation for disability paid?  

...weeks' compensation; both ears, 200 weeks' compensation. (14) Breast (one) lost: 52 weeks' compensation. (15) Kidney (one) lost: 156 weeks' compensation. (16) Larynx lost: 160 weeks' compensation. (17) Lung (one) lost:...

2014-04-01

425

20 CFR 25.100 - How is compensation for disability paid?  

Code of Federal Regulations, 2010 CFR

...51 weeks' compensation. (7) First finger lost: 28 weeks' compensation. (8...26 weeks' compensation. (9) Second finger lost: 18 weeks' compensation. (10) Third finger lost: 17 weeks' compensation....

2010-04-01

426

20 CFR 25.100 - How is compensation for disability paid?  

Code of Federal Regulations, 2011 CFR

...51 weeks' compensation. (7) First finger lost: 28 weeks' compensation. (8...26 weeks' compensation. (9) Second finger lost: 18 weeks' compensation. (10) Third finger lost: 17 weeks' compensation....

2011-04-01

427

Atmospheric Optics  

NSDL National Science Digital Library

Les Cowley, a physicist and expert in atmospheric optics, developed this website to share his knowledge about the visual spectacles produced by light connecting with water drops, dust, and ice crystals. Students can discover how and where the amazing displays are formed. The site is divided into five main categories: Rays and Shadows, Water Droplets, Rainbows, Ice Halos, and High Atmosphere. Within each topic, users can find an abundance of information and amazing images of the particular spectacle. By downloading the HaloSim3 Software in the Ice Halo link, users can view simulations of common and rare halos. Visitors will learn a lot about the atmosphere through this remarkable website.

Cowley, Les

428

Planetary Atmospheres  

NASA Astrophysics Data System (ADS)

Observation, characterization, and understanding the atmospheres of our neighboring planets and moons in the solar system provide essential inputs for addressing broad science goals. These goals include identifying the conditions that are favorable for producing and supporting biological activity, managing the effects of human activity on the Earth's atmosphere, and planning and evaluating observations of extra-solar planets. Here we review the current state of knowledge, pose key science questions, recommend enhancements in the research infrastructure for investigation of planetary atmospheres, and propose new space missions with specific science objectives.

Huestis, D. L.; Adams, N. G.; Atreya, S. K.; Baines, K. H.; Beebe, R. F.; Bolton, S. J.; Bougher, S. W.; Coustenis, A.; Edgington, S. G.; Friedson, A. J.; Galand, M.; Griffith, C. A.; Guberman, S. L.; Hammel, H. B.; Hofstadter, M. D.; Ingersoll, A. P.; Lunine, J. I.; Mendillo, M.; Moses, J.; Mueller-Wodarg, I.; Orton, G. S.; Rages, K. A.; Slanger, T. G.; Titov, D. V.; Vasavada, A. R.; Wong, A.-S.; Yelle, R.

2002-08-01

429

Temperature compensation and entrainment in circadian rhythms  

NASA Astrophysics Data System (ADS)

To anticipate daily variations in the environment and coordinate biological activities into a daily cycle many organisms possess a circadian clock. In the absence of external time cues the circadian rhythm persists with a period of approximately 24?h. The clock phase can be shifted by single pulses of light, darkness, chemicals, or temperature and this allows entrainment of the clock to exactly 24 h by cycles of these zeitgebers. On the other hand, the period of the circadian rhythm is kept relatively constant within a physiological range of constant temperatures, which means that the oscillator is temperature compensated. The mechanisms behind temperature compensation and temperature entrainment are not fully understood, neither biochemically nor mathematically. Here, we theoretically investigate the interplay of temperature compensation and entrainment in general oscillatory systems. We first give an analytical treatment for small temperature shifts and derive that every temperature-compensated oscillator is entrainable to external small-amplitude temperature cycles. Temperature compensation ensures that this entrainment region is always centered at the endogenous period regardless of possible seasonal temperature differences. Moreover, for small temperature cycles the entrainment region of the oscillator is potentially larger for rectangular pulses. For large temperature shifts we numerically analyze different circadian clock models proposed in the literature with respect to these properties. We observe that for such large temperature shifts sinusoidal or gradual temperature cycles allow a larger entrainment region than rectangular cycles.

Bodenstein, C.; Heiland, I.; Schuster, S.

2012-06-01

430

Energy compensation in enterally fed children.  

PubMed

Limited exposure to solid food in early childhood may affect the development of appetite regulation. We used formal satiation studies to assess energy compensation in children who have been artificially fed. Subjects were 11 children, median age 4.5 years (range 1-10) who were formerly (n=4) or currently (n=5) mainly tube fed or supplement fed (n=2), with a range of surgical or neurodevelopmental problems. On 2 separate days a high-energy preload (HEP) and low-energy preload (LEP) drink were given followed by a multi-item test lunch. A compensation index (COMPX) score was derived as follows: COMPX (%)=[(Meal(lep)-Meal(hep))/(Preload(hep)-Preload(lep))] 100. The median (range) COMPX of the participants was 70% (-73% to 178%). The 8 boys tended to compensate more (median 99%) than the 3 girls (30%; P Mann-Whitney=0.1), but there was no clear association of compensation with age. Although a small preliminary study, this suggests that children who have been artificially fed demonstrate energy compensation comparable to that of normally fed children. PMID:21075153

Kane, Laura; Wright, Charlotte; Fariza, Wan Fathin; Hetherington, Marion

2011-02-01

431

Rapid springback compensation for age forming based on quasi Newton method  

NASA Astrophysics Data System (ADS)

Iterative methods based on finite element simulation are effective approaches to design mold shape to compensate springback in sheet metal forming. However, convergence rate of iterative methods is difficult to improve greatly. To increase the springback compensate speed of designing age forming mold, process of calculating springback for a certain mold with finite element method is analyzed. Springback compensation is abstracted as finding a solution for a set of nonlinear functions and a springback compensation algorithm is presented on the basis of quasi Newton method. The accuracy of algorithm is verified by developing an ABAQUS secondary development program with MATLAB. Three rectangular integrated panels of dimensions 710 mm 750 mm integrated panels with intersected ribs of 10 mm are selected to perform case studies. The algorithm is used to compute mold contours for the panels with cylinder, sphere and saddle contours respectively and it takes 57%, 22% and 33% iterations as compared to that of displacement adjustment (DA) method. At the end of iterations, maximum deviations on the three panels are 0.618 4 mm, 0.624 1 mm and 0.342 0 mm that are smaller than the deviations determined by DA method (0.740 8 mm, 0.740 8 mm and 0.713 7 mm respectively). In following experimental verification, mold contour for another integrated panel with 400 mm380 mm size is designed by the algorithm. Then the panel is age formed in an autoclave and measured by a three dimensional digital measurement devise. Deviation between measuring results and the panel's design contour is less than 1 mm. Finally, the iterations with different mesh sizes (40 mm, 35 mm, 30 mm, 25 mm, 20 mm) in finite element models are compared and found no considerable difference. Another possible compensation method, Broyden-Fletcher-Shanmo method, is also presented based on the solving nonlinear functions idea. The Broyden-Fletcher-Shanmo method is employed to compute mold contour for the second panel. It only takes 50% iterations compared to that of DA. The proposed method can serve a faster mold contour compensation method for sheet metal forming.

Xiong, Wei; Gan, Zhong; Xiong, Shipeng; Xia, Yushan

2014-05-01

432

A novel algorithm combining finite state method and genetic algorithm for solving crude oil scheduling problem.  

PubMed

A hybrid optimization algorithm combining finite state method (FSM) and genetic algorithm (GA) is proposed to solve the crude oil scheduling problem. The FSM and GA are combined to take the advantage of each method and compensate deficiencies of individual methods. In the proposed algorithm, the finite state method makes up for the weakness of GA which is poor at local searching ability. The heuristic returned by the FSM can guide the GA algorithm towards good solutions. The idea behind this is that we can generate promising substructure or partial solution by using FSM. Furthermore, the FSM can guarantee that the entire solution space is uniformly covered. Therefore, the combination of the two algorithms has better global performance than the existing GA or FSM which is operated individually. Finally, a real-life crude oil scheduling problem from the literature is used for conducting simulation. The experimental results validate that the proposed method outperforms the state-of-art GA method. PMID:24772031

Duan, Qian-Qian; Yang, Gen-Ke; Pan, Chang-Chun

2014-01-01

433

A Novel Algorithm Combining Finite State Method and Genetic Algorithm for Solving Crude Oil Scheduling Problem  

PubMed Central

A hybrid optimization algorithm combining finite state method (FSM) and genetic algorithm (GA) is proposed to solve the crude oil scheduling problem. The FSM and GA are combined to take the advantage of each method and compensate deficiencies of individual methods. In the proposed algorithm, the finite state method makes up for the weakness of GA which is poor at local searching ability. The heuristic returned by the FSM can guide the GA algorithm towards good solutions. The idea behind this is that we can generate promising substructure or partial solution by using FSM. Furthermore, the FSM can guarantee that the entire solution space is uniformly covered. Therefore, the combination of the two algorithms has better global performance than the existing GA or FSM which is operated individually. Finally, a real-life crude oil scheduling problem from the literature is used for conducting simulation. The experimental results validate that the proposed method outperforms the state-of-art GA method. PMID:24772031

Duan, Qian-Qian; Yang, Gen-Ke; Pan, Chang-Chun

2014-01-01

434

Exoplanet Atmospheres  

E-print Network

At the dawn of the first discovery of exoplanets orbiting Sun-like stars in the mid-1990s, few believed that observations of exoplanet atmospheres would ever be possible. After the 2002 Hubble Space Telescope detection of ...

Seager, Sara

435

Earth's Atmosphere  

NSDL National Science Digital Library

This problem set is about the methods scientists use to compare the abundance of the different elements in Earth's atmosphere. Answer key is provided. This is part of Earth Math: A Brief Mathematical Guide to Earth Science and Climate Change.

436

Physician accountability, patient safety and patient compensation.  

PubMed

In Canada, the response to adverse medical events follows one or more of three main paths: patient safety, physician accountability and patient compensation. While their goals differ, each of these responses serves a valuable function. There are however competing imperatives inherent in each response, particularly in terms of information disclosure: Effective patient safety depends on the full and protected disclosure of all information relevant to an adverse event and requires a "no blame" environment. While natural justice demands that a physician be held accountable for his actions, the doctor should be accorded the right of due process and be judged against an established standard of care. This is necessarily a fault-finding activity. Patient compensation meets both accountability demands and the social justice imperatives of supporting a patient injured through physician negligence. The most effective approach is one that achieves balance between competing imperatives. With clear information disclosure rules, patient safety, physician accountability and patient compensation can operate synergistically. PMID:16900793

Gray, John E

2006-01-01

437

Attitude control compensator for flexible spacecraft  

NASA Technical Reports Server (NTRS)

An attitude control loop for a spacecraft uses a proportional-integral-derivative (PID) controller for control about an axis. The spacecraft body has at least a primary mechanical resonance. The attitude sensors are collocated, or both on the rigid portion of the spacecraft. The flexure attributable to the resonance may result in instability of the system. A compensator for the control loop has an amplitude response which includes a component which rolls off beginning at frequencies below the resonance, and which also includes a component having a notch at a notch frequency somewhat below the resonant frequency. The phase response of the compensator tends toward zero at low frequencies, and tends toward -180.degree. as frequency increases toward the notch frequency. At frequencies above the notch frequency, the phase decreases from +180.degree., becoming more negative, and tending toward -90.degree. at frequencies far above the resonance frequency. Near the resonance frequency, the compensator phase is near zero.

Goodzeit, Neil E. (Inventor); Linder, David M. (Inventor)

1991-01-01

438

Survey of planetary entry guidance algorithms  

NASA Astrophysics Data System (ADS)

This comprehensive literature survey reviews past and present planetary entry guidance algorithms. The algorithms are categorized based on the vehicle L/D and the planetary atmosphere that the vehicle is entering. Each algorithm is described based on the guidance type, the guidance formulation, and the inclusion of aerothermal parameters. An analysis was completed defining the performance of each guidance algorithm relative to one another within its specific category. Finally, an overall assessment was made regarding the state-of-the-art in spacecraft entry guidance.

D'Souza, Sarah N.; Sarigul-Klijn, Nesrin

2014-07-01

439

The EPEC Algorithm for Vision Guided Manipulation: Analysis and Validation  

NASA Technical Reports Server (NTRS)

This paper describes the simulated performance and experimental validation of a computationally efficient algorithm for improving positioning accuracy of robot arms using low speed feedback from fixed stereo cameras. The algorithm, called End-Effector Position Error Compensation (EPEC) is robust to visual occlusion of the end-effector and does not require high fidelity calibration of either the arm or stereo camera. The algorithm works by calculating an error vector between the locations of a fiducial on the arm's end-effector as predicted by arm kinematics and detected by a stereo camera triangulation. With this knowledge, the commanded target pose is adjusted to compensate for positioning errors. A simulation environment where arbitrary error can be introduced into arm-camera systems is introduced and used to provide an assessment of the performance of the algorithm under both ideal and degraded conditions.

DiCicco, Matthew A.; Bajracharya, Max; Nickels, Kevin; Backes, Paul

2007-01-01

440

Aligning physician compensation with strategic goals.  

PubMed

In 2012, Mayo Clinic Health System (MCHS) had 13 different physician compensation models among its operating units, with most based on productivity metrics. MCHS aimed to transition all physicians to a single compensation model that would facilitate its integration with Mayo Clinic and promote physician engagement with emerging value-based payment models. The new model, which was implemented this past January, incorporates quality metrics, provides physicians with regular reports of their performance, and already has resulted in greater physician attention to outcomes, safety, and patient experience. PMID:25076636

Bunkers, Brian; Koch, Mark; McDonough, Becky; Whited, Brian

2014-07-01

441

Dispersion compensation for optical coherence tomography  

NASA Astrophysics Data System (ADS)

Optical coherence tomography (OCT) is an imaging technique widely used in various applications especially in biomedical field. It constructs a high resolution 3-D image using multiple cross-sectional views. The axial resolution can be degraded if the sample is dispersive, which is usually true as most of the samples are living tissues. For time-domain OCT, this dispersion is minimized numerically by introducing a compensation filter, which is applied to the obtained signal in Wigner domain, a time-frequency domain. The filter is designed using simulated annealing optimization technique. This paper shows the design of the filter and the results of dispersion compensation.

Wongpiya, Ranida; Mohammed, Waleed; Sherif, Sherif

2010-05-01

442

Compensation for the intrinsic dynamics of the InMotion2 robot.  

PubMed

The InMotion2 and other similarly designed robots, are commonly used for rehabilitation of neurological injuries and motor adaptation studies. These robots are used to simulate haptic environments; however, anisotropy in end-point impedance due to the intrinsic robot dynamics can compromise these experiments. The goal was to decrease the magnitude and anisotropy of the robot impedance using a dynamic compensation algorithm that reduces the forces normally felt by the user during rapid movements. We tested this algorithm with two different methods for real-time calculation of derivatives, a novel quadratic fit method (CQF) and the commonly used backward derivative method (CBD). Six subjects performed a series of point-to-point movements under three conditions (no compensation, CQF, CBD), in different directions at peak speeds of 50, 100 and 150 cm/s. Without compensation, tangential peak-to-peak forces were as large as 69 N in certain directions at the 150 cm/s speed. Both CQF and CBD significantly reduced tangential forces in all directions and speeds. CQF outperformed CBD in the directions with highest intrinsic impedance, reducing tangential forces by 64% in these directions. Compensation also significantly reduced forces normal to the movement direction, with CQF again outperforming CBD in several cases. Anisotropy was assessed by the range of tangential peak-to-peak forces across movement directions. In the no compensation condition, anisotropy was as high as 52.7 N at the 150 cm/s speed, but an average anisotropy reduction of 74% was achieved with CQF. The CQF method can significantly reduce impedance and anisotropy in this class of robot. PMID:23313756

Nguyen, Hoi B; Lum, Peter S

2013-03-30

443

SINGLE-PHOTON EMISSION COMPUTED TOMOGRAPHY: COMPENSATION FOR CONSTANT ATTENUATION  

SciTech Connect

A back-projection of filtered projection (BKFIL) reconstruction algorithm is presented that is applicable to single-photon emission computed tomography (ECT) in the presence of a constant attenuating medium such as the brain. The filters used in transmission computed tomography (TCT) - comprised of a ramp multiplied by window functions - are modified so that the single-photon ECT filter is a function of the constant attenuation coefficient. The filters give good reconstruction results with sufficient angular and lateral sampling. With continuous samples the BKFIL algorithm has a point spread function that is the Hankel transform of the window function. The resolution and s tistical properties of the filters are demonstrated by various simulations. Statistical formulas for the reconstructed image show that the square of the percent-root-mean square uncertainty (%RMS) of the reconstruction is inversely proportional to the total measured counts. The results indicate that constant attenuation can be compensated for in single-photon ECT by using an attenuation-dependent filter that reconstructs the transverse section reliably. Computer time requirements are two times that of conventional TCT or positron ECT and there is no increase in memory requirements.

Gullberg, Grant T.; Budinger, Thomas F.

1980-06-01

444

Introduction to Algorithms Part 2: Greedy Algorithms  

E-print Network

Introduction to Algorithms Part 2: Greedy Algorithms Dynamic Programming Graph Algorithms 1) Greedy) Books c Wayne Goddard, Clemson University, 2004 #12;Chapter 1: Greedy Algorithms and Spanning Trees In a greedy algorithm, the optimal solution is built up one piece at a time. At each stage the best feasible

Goddard, Wayne

445

Rainfall and Radiative Heating Rates from TOGA COARE Atmospheric Budgets  

Microsoft Academic Search

Atmospheric heat and moisture budgets are used to determine rainfall and radiative heating rates over the western Pacific warm pool during the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). Results are compared to independent estimates of these quantities from the other sources. Using the COARE bulk flux algorithm to estimate surface evaporation over the intensive flux array

Richard H. Johnson; Paul E. Ciesielski

2000-01-01

446

A Revision of the NASA Team Sea Ice Algorithm  

NASA Technical Reports Server (NTRS)

In a recent paper, two operational algorithms to derive ice concentration from satellite multichannel passive microwave sensors have been compared. Although the results of these, known as the NASA Team algorithm and the Bootstrap algorithm, have been validated and are generally in good agreement, there are areas where the ice concentrations differ, by up to 30%. These differences can be explained by shortcomings in one or the other algorithm. Here, we present an algorithm which, in addition to the 19 and 37 GHz channels used by both the Bootstrap and NASA Team algorithms, makes use of the 85 GHz channels as well. Atmospheric effects particularly at 85 GHz are reduced by using a forward atmospheric radiative transfer model. Comparisons with the NASA Team and Bootstrap algorithm show that the individual shortcomings of these algorithms are not apparent in this new approach. The results further show better quantitative agreement with ice concentrations derived from NOAA AVHRR infrared data.

Markus, T.; Cavalieri, Donald J.

1998-01-01

447

Smoothing of respiratory motion traces for motion-compensated radiotherapy  

SciTech Connect

Purpose: The CyberKnife system has been used successfully for several years to radiosurgically treat tumors without the need for stereotactic fixation or sedation of the patient. It has been shown that tumor motion in the lung, liver, and pancreas can be tracked with acceptable accuracy and repeatability. However, highly precise targeting for tumors in the lower abdomen, especially for tumors which exhibit strong motion, remains problematic. Reasons for this are manifold, like the slow tracking system operating at 26.5 Hz, and using the signal from the tracking camera ''as is''. Since the motion recorded with the camera is used to compensate for system latency by prediction and the predicted signal is subsequently used to infer the tumor position from a correlation model based on x-ray imaging of gold fiducials around the tumor, camera noise directly influences the targeting accuracy. The goal of this work is to establish the suitability of a new smoothing method for respiratory motion traces used in motion-compensated radiotherapy. The authors endeavor to show that better prediction--With a lower rms error of the predicted signal--and/or smoother prediction is possible using this method. Methods: The authors evaluated six commercially available tracking systems (NDI Aurora, PolarisClassic, Polaris Vicra, MicronTracker2 H40, FP5000, and accuTrack compact). The authors first tracked markers both stationary and while in motion to establish the systems' noise characteristics. Then the authors applied a smoothing method based on the a trous wavelet decomposition to reduce the devices' noise level. Additionally, the smoothed signal of the moving target and a motion trace from actual human respiratory motion were subjected to prediction using the MULIN and the nLMS{sub 2} algorithms. Results: The authors established that the noise distribution for a static target is Gaussian and that when the probe is moved such as to mimic human respiration, it remains Gaussian with the exception of the FP5000 and the Aurora systems. The authors also showed that the proposed smoothing method can indeed be used to filter noise. The signal's jitter dropped by as much as 95% depending on the tracking system employed. Subsequently, the 3D prediction error (rms) for a prediction horizon of 150 ms on a synthetic signal dropped by up to 37% when using a normalized LMS prediction algorithm (nLMS{sub 2}) and hardly changed when using a MULIN algorithm. When smoothing a real signal obtained in our laboratory, the improvement of prediction was similar: Up to 30% for both the nLMS{sub 2} and the best MULIN algorithm. The authors also found a noticeable increase in smoothness of the predicted signal, the relative jitter dropped by up to 95% on the real signal, and on the simulated signal. Conclusions: In conclusion, the authors can say that preprocessing of marker data is very useful in motion-compensated radiotherapy since the quality of prediction increases. This will result in better performance of the correlation model. As a side effect, since the prediction of a preprocessed signal is also less noisy, the authors expect less robot vibration resulting in better targeting accuracy and less strain on the robot gears.

Ernst, Floris; Schlaefer, Alexander; Schweikard, Achim [Institute for Robotics and Cognitive Systems, University of Luebeck, Ratzeburger Allee 160, Luebeck SH 23538 (Germany)

2010-01-15

448

Efficient Geolocation of InSAR Images from Motion Compensation Processors  

NASA Astrophysics Data System (ADS)

We present an efficient and closed-form algorithm for the geolocation of InSAR images resulting from data processors using motion compensation methods in which the known orbits are corrected and processed to a circular arc reference track. We outline here a derivation utilizing the SCH coordinate system, although our approach may be readily applied to any such processor with suitable changes in coordinate definitions. Motion compensation has been traditionally employed in airborne systems, where the instability of the aircraft trajectories presents issues in the accuracy of the processed phase. However, we have found that motion compensation techniques allowing precise output pixel location are useful in both airborne and spaceborne systems; thus, we present an approach that exploits the simplicity of a properly chosen motion compensation reference geometry. Assuming a circular reference track, we develop a closed form set of equations relating the position of a given DEM pixel to that of the radar. Once position and slant-range are known along the reference arc, we interpolate into the uniformly spaced radar image, avoiding the use of computationally intensive irregular interpolation algorithms. Hence, the resulting equations are simple and lead to a solution that is remarkably fast without sacrificing precision. We demonstrate results from the ALOS platform, validated against the set of corner reflectors deployed by the Jet Propulsion Laboratory at the Rosamond Calibration Array outside of Palmdale, California. Here we see ground projection errors with accuracy on the order of less than a pixel (< 15 m). In addition, we present an extension to our algorithm where the processed Doppler centroid has known range-dependence but with no simple functional form. To accommodate this most general case, we must replace the closed-form equations with an iterative solution. We illustrate these results using data from the NASA/JPL UAVSAR sensor, where we see fast convergence in no more than five iterations.

Wortham, C.; Zebker, H. A.

2010-12-01

449

Weak greedy algorithms  

Microsoft Academic Search

Theoretical greedy type algorithms are studied: a Weak Greedy Algorithm, a Weak Orthogonal Greedy Algorithm, and a Weak Relaxed\\u000a Greedy Algorithm. These algorithms are defined by weaker assumptions than their analogs the Pure Greedy Algorithm, an Orthogonal\\u000a Greedy Algorithm, and a Relaxed Greedy Algorithm. The weaker assumptions make these new algorithms more ready for practical\\u000a implementation. We prove the convergence

Vladimir N. Temlyakov

2000-01-01

450

Algorithm for Autonomous Landing  

NASA Technical Reports Server (NTRS)

Because of their small size, high maneuverability, and easy deployment, micro aerial vehicles (MAVs) are used for a wide variety of both civilian and military missions. One of their current drawbacks is the vast array of sensors (such as GPS, altimeter, radar, and the like) required to make a landing. Due to the MAV s small payload size, this is a major concern. Replacing the imaging sensors with a single monocular camera is sufficient to land a MAV. By applying optical flow algorithms to images obtained from the camera, time-to-collision can be measured. This is a measurement of position and velocity (but not of absolute distance), and can avoid obstacles as well as facilitate a landing on a flat surface given a set of initial conditions. The key to this approach is to calculate time-to-collision based on some image on the ground. By holding the angular velocity constant, horizontal speed decreases linearly with the height, resulting in a smooth landing. Mathematical proofs show that even with actuator saturation or modeling/ measurement uncertainties, MAVs can land safely. Landings of this nature may have a higher velocity than is desirable, but this can be compensated for by a cushioning or dampening system, or by using a system of legs to grab onto a surface. Such a monocular camera system can increase vehicle payload size (or correspondingly reduce vehicle size), increase speed of descent, and guarantee a safe landing by directly correlating speed to height from the ground.

Kuwata, Yoshiaki

2011-01-01

451

Error Compensation for Cricket Indoor Location System  

Microsoft Academic Search

Cricket is a fine-grained indoor location system utilizing beacons transmitting both ultrasound and radio wave signals. However, the system accuracy is greatly impacted by the relative angle and distance between the beacon and listener. This paper proposes a low cost method to improve the system precision by means of incremental error compensation. The ultrasonic detecting error, which directly affects the

Shuqiao Zhou; Haoran Feng; Ruixi Yuan

2009-01-01

452

Compensated telescope system with programmable diffractive optic  

Microsoft Academic Search

Diffractive wavefront control with programmable optically efficient modulo gratings has been successfully demonstrated as a means of compensating large optical aberrations and steering an outgoing beam over small angles without mechanical motion. This work builds on past work to demonstrate the integrated performance of a programmable diffractive element of large pixel count with a telescope system. More specifically, a liquid-crystal-based

Mark T. Gruneisen; Lewis F. DeSandre; Raymond C. Dymale; James R. Rotg; Donald L. Lubin

2005-01-01

453

7 CFR 301.74-5 - Compensation.  

Code of Federal Regulations, 2012 CFR

...compensation for losses associated with the destruction of trees in order to control plum pox pursuant to an...ii) of this section. (2) Owners of fruit tree nurseries. The owner of a fruit tree nursery will be eligible to receive...

2012-01-01

454

7 CFR 301.74-5 - Compensation.  

Code of Federal Regulations, 2011 CFR

...compensation for losses associated with the destruction of trees in order to control plum pox pursuant to an...ii) of this section. (2) Owners of fruit tree nurseries. The owner of a fruit tree nursery will be eligible to receive...

2011-01-01

455

7 CFR 301.74-5 - Compensation.  

Code of Federal Regulations, 2010 CFR

...compensation for losses associated with the destruction of trees in order to control plum pox pursuant to an...ii) of this section. (2) Owners of fruit tree nurseries. The owner of a fruit tree nursery will be eligible to receive...

2010-01-01

456

Division of Human Resources Calculating Overtime Compensation  

E-print Network

and Leave Calculation Overtime Compensation Form questions: (813) 974-5717 Rev. 04/2010 The Fair Labor worked in Payroll Certs in the overtime field. GEMS will automatically calculate overtime hours at 1, overtime will normally be paid by the secondary (Temporary) employer. Holiday hours and any leave hours

Meyers, Steven D.

457

The Compensation Act 2006 and School Trips  

ERIC Educational Resources Information Center

The Compensation Act 2006 received its Royal Assent on 25 July 2006. The Act allows the courts to have regard to the social utility of "desirable activities", including school trips, in considering negligence claims. The article reviews the law of negligence as it affects teachers of the very young and considers the possible impact of the

Hunter-Jones, John

2006-01-01

458

Fast compensation of current transformer saturation  

Microsoft Academic Search

This paper presents a novel method for current transformer (CT) saturation detection and compensation. In the method, CT saturation characteristics are represented by a partial nonlinear regression model. The parameters of this model can be estimated rapidly and accurately using both unsaturated and saturated sections of the waveform of a secondary fault current, even in a heavy saturation scenario, where

D. Y. Shi; J. Buse; Q. H. Wu; L. Jiang

2010-01-01

459

On Compensation in Multidimensional Response Modeling  

ERIC Educational Resources Information Center

The issue of compensation in multidimensional response modeling is addressed. We show that multidimensional response models are compensatory in their ability parameters if and only if they are monotone. In addition, a minimal set of assumptions is presented under which the MLEs of the ability parameters are also compensatory. In a recent series of

van der Linden, Wim J.

2012-01-01

460

Delay Compensation in Networked Computer Games  

E-print Network

players in a virtual environment. As a result, games such as these are highly interactive and tendDelay Compensation in Networked Computer Games Robert F. Buchheit January, 2004 Master's Project #12;2 Table of Contents Abstract 1. Introduction 2. Background 3. Game Development Prototype Game

Liberatore, Vincenzo

461

Federal Employee's Compensation Act (FECA) & OWCP Overview  

E-print Network

stress or strain Identifiable by time and place of occurrence and member of body affected; caused within cont. S h d l A dSchedule Awards Compensation for permanent los of use of specific body part: Arm, Leg - Claim for Traumatic Injury A wound or other condition of the body caused by external force including

US Army Corps of Engineers

462

Adaptive temperature compensation in circadian oscillations.  

PubMed

A temperature independent period and temperature entrainment are two defining features of circadian oscillators. A default model of distributed temperature compensation satisfies these basic facts yet is not easily reconciled with other properties of circadian clocks, such as many mutants with altered but temperature compensated periods. The default model also suggests that the shape of the circadian limit cycle and the associated phase response curves (PRC) will vary since the average concentrations of clock proteins change with temperature. We propose an alternative class of models where the twin properties of a fixed period and entrainment are structural and arise from an underlying adaptive system that buffers temperature changes. These models are distinguished by a PRC whose shape is temperature independent and orbits whose extrema are temperature independent. They are readily evolved by local, hill climbing, optimization of gene networks for a common quality measure of biological clocks, phase anticipation. Interestingly a standard realization of the Goodwin model for temperature compensation displays properties of adaptive rather than distributed temperature compensation. PMID:22807663

Franois, Paul; Despierre, Nicolas; Siggia, Eric D

2012-01-01

463

Bobbing for Widgets: Compensating Wage Differentials  

ERIC Educational Resources Information Center

The authors describe a classroom game that introduces the concept of compensating wage differentials by allowing students to negotiate over the assignment of jobs and wages. Two jobs are designed so that neither job requires special skills, but one is significantly more unpleasant than the other. By varying the job titles and duties, students can

Eckel, Catherine; McInnes, Melayne Morgan; Solnick, Sara; Ensminger, Jean; Fryer, Rolan