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1

Implementation and performance of stochastic parallel gradient descent algorithm for atmospheric turbulence compensation  

NASA Astrophysics Data System (ADS)

IERUS Technologies, Inc. and the University of Alabama in Huntsville have partnered to perform characterization and development of algorithms and hardware for adaptive optics. To date the algorithm work has focused on implementation of the stochastic parallel gradient descent (SPGD) algorithm. SPGD is a metric-based approach in which a scalar metric is optimized by taking random perturbative steps for many actuators simultaneously. This approach scales to systems with a large number of actuators while maintaining bandwidth, while conventional methods are negatively impacted by the very large matrix multiplications that are required. The metric approach enables the use of higher speed sensors with fewer (or even a single) sensing element(s), enabling a higher control bandwidth. Furthermore, the SPGD algorithm is model-free, and thus is not strongly impacted by the presence of nonlinearities which degrade the performance of conventional phase reconstruction methods. Finally, for high energy laser applications, SPGD can be performed using the primary laser beam without the need for an additional beacon laser. The conventional SPGD algorithm was modified to use an adaptive gain to improve convergence while maintaining low steady state error. Results from laboratory experiments using phase plates as atmosphere surrogates will be presented, demonstrating areas in which the adaptive gain yields better performance and areas which require further investigation.

Finney, Greg A.; Persons, Christopher M.; Henning, Stephan; Hazen, Jessie; Whitley, Daniel

2014-06-01

2

A spectral climatology for atmospheric compensation  

NASA Astrophysics Data System (ADS)

Most Earth observation hyperspectral imagery (HSI) detection and identification algorithms depend critically upon a robust atmospheric compensation capability to correct for the effects of the atmosphere on the radiance signal. Atmospheric compensation methods typically perform optimally when ancillary ground truth data are available, e.g., high fidelity in situ radiometric observations or atmospheric profile measurements. When ground truth is incomplete or not available, additional assumptions must be made to perform the compensation. Meteorological climatologies are available to provide climatological norms for input into the radiative transfer models; however no such climatologies exist for empirical methods. The success of atmospheric compensation methods such as the empirical line method suggests that remotely sensed HSI scenes contain comprehensive sets of atmospheric state information within the spectral data itself. It is argued that large collections of empirically-derived atmospheric coefficients collected over a range of climatic and atmospheric conditions comprise a resource that can be applied to prospective atmospheric compensation problems. This paper introduces a new climatological approach to atmospheric compensation in which empirically derived spectral information, rather than sensible atmospheric state variables, is the fundamental datum. An experimental archive of airborne HSI data is mined for representative atmospheric compensation coefficients, which are assembled in a scientific database of spectral and sensible atmospheric observations. We present the empirical techniques for extracting the coefficients, the modeling methods used to standardize the coefficients across varying collection and illumination geometries, and the resulting comparisons of adjusted coefficients. Preliminary results comparing normalized coefficients from representative scenes across several distinct environments are presented, along with a discussion of the potential benefits, shortfalls and future work to fully develop the new technique.

Powell, John H.; Resmini, Ronald G.

2014-06-01

3

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

4

Rain compensation algorithm using adaptive linear prediction  

NASA Technical Reports Server (NTRS)

Rain compensation algorithm using adaptive linear prediction is presented in viewgraph form. Topics covered include AMT scenario, summary of AMT-RCA, empirical basis for reducing attenuation extrapolation errors, and candidate adaptive 1-pole prediction filter for application to AMT-RCA (at the mobile terminal (MT)).

Satorius, Edgar

1992-01-01

5

Atmospheric Compensation for Uplink Arrays via Radiometry  

NASA Technical Reports Server (NTRS)

Uplink arrays for communications applications are gaining increased visibility within the NASA and military community due to the enhanced flexibility and reliability they provide. When compared with the conventional large, single aperture antennas currently comprising the Deep Space Network (DSN), for example, smaller aperture antenna arrays have the benefits of providing fault tolerance (reduced single-point failure), reduced maintenance cost, and enhanced capabilities such as electronic beam-steering and multi-beam operation. However, signal combining of antenna array elements spaced many wavelengths apart becomes problematic due to the inherent instability of earth's turbulent atmosphere, particularly at the frequencies of interest to the DSN (i.e., Ka-band). Degradation in the power combining of the individual elements comprising the array arises due to uncorrelated phase errors introduced as the signals propagate through the troposphere. It is well known that the fundamental source of this error is due to the inhomogeneous distribution of water vapor in the atmosphere [1]. Several techniques have been proposed to circumvent this issue, including the use of phase calibration towers and a moon bounce to generate a feedback loop which would provide a means of intermittent calibration of the system phase errors (thermal drifts, atmosphere) [2,3]. However, these techniques require repositioning of the antenna elements to perform this operation which ultimately results in reduced system availability. And, though they are sufficient for compensating for slow varying phase drifts, they are insufficient to compensate for faster varying phase errors, such as those introduced by the atmosphere. In this paper, preliminary radiometry and interferometry measurements collected by the NASA Glenn Research Center are analyzed and indicate that the use of optimized water vapor radiometers as a feedback system in a communications platform could provide the necessary atmospheric compensation technique to enhance the beamforming of uplink arrays.

Nessel, James A.; Acosta, Roberto J.

2010-01-01

6

High-Precision Ventilator with Compensation Algorithm and Automatic Regulation  

Microsoft Academic Search

CPAP (Continuous Positive Airway Pressure) ventilator is designed based on compensation algorithm and Automatic Regulation. With the use of patient status and system changes in the environment, breathing machine through the compensation algorithm will be dynamically adjusted accordingly. The compensation algorithm, taking into account regional differences in altitude, the pressure, masks and flow loop caused by the pressure of the

Peng An; Jia-tao Song

2010-01-01

7

Rain compensation algorithm for ACTS mobile terminal  

NASA Technical Reports Server (NTRS)

The initial advanced communication technology satellite (ACTS) mobile terminal (AMT) demonstrations will involve two-way communications between the high-bit-rate link evaluation terminal (HBR-LET), which is a fixed terminal (FT), and a van-housed mobile terminal (MT). The HBR-LET has the capability of adjusting its transmitted uplink power over an approximately 10-dB range to compensate for forward uplink rain attenuation. However, because of size and weight limitations, the MT cannot use power control as a rain compensation technique. Consequently, the AMT rain compensation algorithm (RCA) is based on a formula for varying the transmitted data rate in either direction to maintain link performance within acceptable limits. The objective of the AMT RCA is to ensure reliable operation in both the forward and return directions despite the possibility of uplink or downlink fading due to rain events in the vicinity of the FT or MT. In particular, the RCA must maintain at least a 3-dB link margin at the highest possible transmission rate (AMT can operate at 9.6, 4.8, or 2.4 kb/s) permitted by the prevailing channel conditions. The 3-dB minimum link margin is a system design safety factor to accommodate conceivable implementation losses.

Levitt, Barry K.

1992-01-01

8

KALMAN FILTER WITH PHASE SPECTRUM COMPENSATION ALGORITHM FOR SPEECH ENHANCEMENT  

E-print Network

KALMAN FILTER WITH PHASE SPECTRUM COMPENSATION ALGORITHM FOR SPEECH ENHANCEMENT Stephen So, Kamil K.lyons, a.stark, k.paliwal}@griffith.edu.au ABSTRACT In this paper, we propose to combine the Kalman filter specifically, we apply the PSC tech- nique to initialise the Kalman filter, whereby PSC is used to clean

9

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

E-print Network

Bjerknes 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 are investigated, using data output from a preindustrial control run of the Third Hadley Centre Coupled Ocean­Atmosphere

Drijfhout, Sybren

10

A spatially adaptive fast atmospheric correction algorithm  

Microsoft Academic Search

An atmospheric correction algorithm for high spatial resolution satellite sensors like Landsat Thematic Mapper (TM) has been developed. The algorithm works with a catalogue of atmospheric correction functions stored in look-up tables. The catalogue consists of a broad range of atmospheric conditions (different altitude profiles of pressure, air temperature, and humidity; several aerosol types; ground elevations from 0-1?km above sea

R. Richter

1996-01-01

11

Weighted depth compensation algorithm for fluorescence molecular tomography reconstruction.  

PubMed

In fluorescence molecular tomography (FMT), diffuse-light measurements are obtained from a series of source-detector pairs placed on the boundary of the medium. The sensitivity of measurements deteriorates quickly with increased distance from the sources and detectors and therefore yields poor depth quantitative recovery. A depth compensation algorithm is presented in this paper to reconstruct fluorescent inclusions in deep tissues. Two weight matrixes are employed to level off sensitivity differences and enhance prominent elements of the solution. Results of numerical and phantom experiments demonstrate that both relative quantitation and spatial resolution of FMT are improved for inclusions at different depths. PMID:23262629

Liu, Fei; Li, Mingze; Zhang, Bin; Luo, Jianwen; Bai, Jing

2012-12-20

12

A new chromatic dispersion compensation method based on genetic algorithm  

NASA Astrophysics Data System (ADS)

In the 40Gbps high-speed optical fiber communication system, chromatic dispersion of optical signal brings about to generation of inter-symbol interface which influences the quality of optical fiber communication. In order to solve the above questions in the 40Gbps differential quarter phase-shift keying (DQPSK) optical fiber communication system, a new method of chromatic dispersion compensation based on genetic algorithm is proposed according to the demodulation of DQPSK optical signal and the trait of chromatic dispersion. Result shows that the system's receiving sensitivity has been enhanced up to six orders of magnitude.

Liu, Chun-wu; Qin, Jiang-yi; Huang, Zhi-ping; Zhang, Yi-meng

2013-08-01

13

Fast Inverse Motion Compensation Algorithms for MPEG-2 and for Partial DCT Information  

E-print Network

Fast Inverse Motion Compensation Algorithms for MPEG-2 and for Partial DCT Information Neri Merhav, we developed a fast inverse motion compensation method that can be implemented directly on the DCT extend the prior work to speedup the inverse motion compensation process in the DCT domain by explicitly

Merhav, Neri

14

Retrieval of atmospheric properties from hyper and multispectral imagery with the FLAASH atmospheric correction algorithm  

NASA Astrophysics Data System (ADS)

Atmospheric Correction Algorithms (ACAs) are used in applications of remotely sensed Hyperspectral and Multispectral Imagery (HSI/MSI) to correct for atmospheric effects on measurements acquired by air and space-borne systems. The Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) algorithm is a forward-model based ACA created for HSI and MSI instruments which operate in the visible through shortwave infrared (Vis-SWIR) spectral regime. Designed as a general-purpose, physics-based code for inverting at-sensor radiance measurements into surface reflectance, FLAASH provides a collection of spectral analysis and atmospheric retrieval methods including: a per-pixel vertical water vapor column estimate, determination of aerosol optical depth, estimation of scattering for compensation of adjacency effects, detection/characterization of clouds, and smoothing of spectral structure resulting from an imperfect atmospheric correction. To further improve the accuracy of the atmospheric correction process, FLAASH will also detect and compensate for sensor-introduced artifacts such as optical smile and wavelength mis-calibration. FLAASH relies on the MODTRANTM radiative transfer (RT) code as the physical basis behind its mathematical formulation, and has been developed in parallel with upgrades to MODTRAN in order to take advantage of the latest improvements in speed and accuracy. For example, the rapid, high fidelity multiple scattering (MS) option available in MODTRAN4 can greatly improve the accuracy of atmospheric retrievals over the 2-stream approximation. In this paper, advanced features available in FLAASH are described, including the principles and methods used to derive atmospheric parameters from HSI and MSI data. Results are presented from processing of Hyperion, AVIRIS, and LANDSAT data.

Perkins, Timothy; Adler-Golden, Steven; Matthew, Michael; Berk, Alexander; Anderson, Gail; Gardner, James; Felde, Gerald

2005-10-01

15

Sensor Saturation Compensated Smoothing Algorithm for Inertial Sensor Based Motion Tracking  

PubMed Central

In this paper, a smoothing algorithm for compensating inertial sensor saturation is proposed. The sensor saturation happens when a sensor measures a value that is larger than its dynamic range. This can lead to a considerable accumulated error. To compensate the lost information in saturated sensor data, we propose a smoothing algorithm in which the saturation compensation is formulated as an optimization problem. Based on a standard smoothing algorithm with zero velocity intervals, two saturation estimation methods were proposed. Simulation and experiments prove that the proposed methods are effective in compensating the sensor saturation. PMID:24806740

Dang, Quoc Khanh; Suh, Young Soo

2014-01-01

16

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

17

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

18

Analytical brightness compensation algorithm for traditional polygon-based method in computer-generated holography.  

PubMed

In three-dimensional (3D) holographic display, current brightness compensation algorithm of the traditional polygon-based method experimentally obtains the compensation factor, which depends on the fabrication process. In this paper, we proposed an analytical brightness compensation method discarding the influence of the fabrication. The surface property function with the flat power spectral density and the compensation factor obtained from the simplified relationship between the original and the rotated frequencies are used to analytically compensate the radiant energy of the tilted polygon. The optical reconstruction results show the proposed method could effectively compensate the brightness and ensure the further shading process. The proposed method separates the brightness compensation from the fabrication process, which is important for deepening the investigation of the hologram fabrication and achieving realistic 3D reconstruction. PMID:23842184

Pan, Yijie; Wang, Yongtian; Liu, Juan; Li, Xin; Jia, Jia; Zhang, Zhao

2013-06-20

19

Error-Compensating Phase Measuring Algorithms in a Fizeau Inter ferometer  

Microsoft Academic Search

In phase-shifting Fizeau interferometers, nonlinear motion of the phase shifter and multiple-beam interference are the most common sources of systematic errors affecting high-precision phase measurement. A new class of algorithms with extended compensating capability for these errors is proposed. Measurement errors for the new algorithms and two groups of conventional algorithms: discrete Fourier algorithms and the Schwider-Larkin-Hibino algorithms are estimated

Kenichi Hibino

1999-01-01

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

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

22

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

23

Design of automatic leveling and centering system based on error correction and compensation algorithm  

NASA Astrophysics Data System (ADS)

Because of the interaction of leveling and centering, the operation repeats many times; Angle measurement error caused by the leveling and centering is not compensated and corrected. Aimed at defects such as low precision, long time, low intellectualization and no compensation in traditional method of leveling and centering, automatic leveling and centering system of theodolite is designed based on the algorithm of error correction and compensation. Using the method of coordinate transformation, horizontal angle error caused by tilt error are analyzed, and the exact mathematical compensation formulas are given. The structure and operating principle of automatic leveling and centering system based on the algorithm are set forth. The compensation algorithm is used for compensating the horizontal and vertical angle effectively. Experiments show that the centering precision reaches 0.04mm through error compensation, and the angle measuring error caused by leveling error is less than 0.5". The system can effectively avoid leveling and centering many times, shorten the equipment set-up time, and improve angle measurement precision.

Liu, Chun-tong; He, Zhen-xin; Zhao, Xiao-feng; Zhao, Bing

2010-10-01

24

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

25

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

26

Improved Fault Classification in Series Compensated Transmission Line: Comparative Evaluation of Chebyshev Neural Network Training Algorithms.  

PubMed

This paper presents the Chebyshev neural network (ChNN) as an improved artificial intelligence technique for power system protection studies and examines the performances of two ChNN learning algorithms for fault classification of series compensated transmission line. The training algorithms are least-square Levenberg-Marquardt (LSLM) and recursive least-square algorithm with forgetting factor (RLSFF). The performances of these algorithms are assessed based on their generalization capability in relating the fault current parameters with an event of fault in the transmission line. The proposed algorithm is fast in response as it utilizes postfault samples of three phase currents measured at the relaying end corresponding to half-cycle duration only. After being trained with only a small part of the generated fault data, the algorithms have been tested over a large number of fault cases with wide variation of system and fault parameters. Based on the studies carried out in this paper, it has been found that although the RLSFF algorithm is faster for training the ChNN in the fault classification application for series compensated transmission lines, the LSLM algorithm has the best accuracy in testing. The results prove that the proposed ChNN-based method is accurate, fast, easy to design, and immune to the level of compensations. Thus, it is suitable for digital relaying applications. PMID:25314714

Vyas, Bhargav Y; Das, Biswarup; Maheshwari, Rudra Prakash

2014-10-13

27

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

28

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

29

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

30

Note: atmospheric point discharge current measurements using a temperature-compensated logarithmic current amplifier.  

PubMed

Measurements of atmospheric corona currents have been made for over 100 years to indicate the atmospheric electric field. Corona currents vary substantially, in polarity and in magnitude. The instrument described here uses a sharp point sensor connected to a temperature compensated bi-polar logarithmic current amplifier. Calibrations over a range of currents from ±10 fA to ±3 ?A and across ±20 °C show it has an excellent logarithmic response over six orders of magnitude from 1 pA to 1 ?A in both polarities for the range of atmospheric temperatures likely to be encountered in the southern UK. Comparison with atmospheric electric field measurements during disturbed weather confirms that bipolar electric fields induce corona currents of corresponding sign, with magnitudes ~0.5 ?A. PMID:23822390

Marlton, G J; Harrison, R G; Nicoll, K A

2013-06-01

31

MTRC compensation in high-resolution ISAR imaging via improved polar format algorithm  

NASA Astrophysics Data System (ADS)

Migration through resolution cells (MTRC) is generated in high-resolution inverse synthetic aperture radar (ISAR) imaging. A MTRC compensation algorithm for high-resolution ISAR imaging based on improved polar format algorithm (PFA) is proposed in this paper. Firstly, in the situation that a rigid-body target stably flies, the initial value of the rotation angle and center of the target is obtained from the rotation of radar line of sight (RLOS) and high range resolution profile (HRRP). Then, the PFA is iteratively applied to the echo data to search the optimization solution based on minimum entropy criterion. The procedure starts with the estimated initial rotation angle and center, and terminated when the entropy of the compensated ISAR image is minimized. To reduce the computational load, the 2-D iterative search is divided into two 1-D search. One is carried along the rotation angle and the other one is carried along rotation center. Each of the 1-D searches is realized by using of the golden section search method. The accurate rotation angle and center can be obtained when the iterative search terminates. Finally, apply the PFA to compensate the MTRC by the use of the obtained optimized rotation angle and center. After MTRC compensation, the ISAR image can be best focused. Simulated and real data demonstrate the effectiveness and robustness of the proposed algorithm.

Liu, Yang; Li, Hao; Li, Na; Xu, Shiyou; Chen, Zengping

2014-10-01

32

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

33

Novel true-motion estimation algorithm and its application to motion-compensated temporal frame interpolation.  

PubMed

In this paper, a new low-complexity true-motion estimation (TME) algorithm is proposed for video processing applications, such as motion-compensated temporal frame interpolation (MCTFI) or motion-compensated frame rate up-conversion (MCFRUC). Regular motion estimation, which is often used in video coding, aims to find the motion vectors (MVs) to reduce the temporal redundancy, whereas TME aims to track the projected object motion as closely as possible. TME is obtained by imposing implicit and/or explicit smoothness constraints on the block-matching algorithm. To produce better quality-interpolated frames, the dense motion field at interpolation time is obtained for both forward and backward MVs; then, bidirectional motion compensation using forward and backward MVs is applied by mixing both elegantly. Finally, the performance of the proposed algorithm for MCTFI is demonstrated against recently proposed methods and smoothness constraint optical flow employed by a professional video production suite. Experimental results show that the quality of the interpolated frames using the proposed method is better when compared with the MCFRUC techniques. PMID:23060328

Dikbas, Salih; Altunbasak, Yucel

2013-08-01

34

A digital combining-weight estimation algorithm for broadband sources with the array feed compensation system  

NASA Technical Reports Server (NTRS)

An algorithm for estimating the optimum combining weights for the Ka-band (33.7-GHz) array feed compensation system was developed and analyzed. The input signal is assumed to be broadband radiation of thermal origin, generated by a distant radio source. Currently, seven video converters operating in conjunction with the real-time correlator are used to obtain these weight estimates. The algorithm described here requires only simple operations that can be implemented on a PC-based combining system, greatly reducing the amount of hardware. Therefore, system reliability and portability will be improved.

Vilnrotter, V. A.; Rodemich, E. R.

1994-01-01

35

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

36

Adaptive Feedforward Compensation Algorithms for Active Vibration Control with Mechanical Coupling and Local Feedback -a unified approach  

E-print Network

Adaptive Feedforward Compensation Algorithms for Active Vibration Control with Mechanical Coupling an internal "positive" mechanical feedback between the compensation system and the reference source (a of a filter on observed data or a filtering of the residual acceleration in order to satisfy some passivity

Boyer, Edmond

37

Comprehensive investigation of three-dimensional diffuse optical tomography with depth compensation algorithm  

NASA Astrophysics Data System (ADS)

A depth compensation algorithm (DCA) can effectively improve the depth localization of diffuse optical tomography (DOT) by compensating the exponentially decreased sensitivity in the deep tissue. In this study, DCA is investigated based on computer simulations, tissue phantom experiments, and human brain imaging. The simulations show that DCA can largely improve the spatial resolution of DOT in addition to the depth localization, and DCA is also effective for multispectral DOT with a wide range of optical properties in the background tissue. The laboratory phantom experiment demonstrates that DCA can effectively differentiate two embedded objects at different depths in the medium. DCA is further validated by human brain imaging using a finger-tapping task. To our knowledge, this is the first demonstration to show that DCA is capable of accurately localizing cortical activations in the human brain in three dimensions.

Niu, Haijing; Lin, Zi-Jing; Tian, Fenghua; Dhamne, Sameer; Liu, Hanli

2010-07-01

38

ENHANCEMENTS TO AN ATMOSPHERIC ASCENT GUIDANCE ALGORITHM  

Microsoft Academic Search

Enhancements to an advanced ascent guidance algorithm for rocket-powered launch vehicles are described. A general method has been developed for conveniently and efficiently handling the common case of (asymmetric) launch vehicles with unbalanced thrust and aerodynamic moments. The new part of this development concerns the treatment of endo-atmosperic flight. An alternative method for handing the transversality conditions has been developed

Greg A. Dukeman

39

MTF compensation algorithm based on blind deconvolution for high-resolution remote sensing satellite  

NASA Astrophysics Data System (ADS)

In high resolution remote sensing satellite imaging system, image restoration is an important step to visualize ne details and mitigate the noise. The raw image data often presents poor imaging quality due to various reasons and Point Spread Function (PSF) measures such blurriness characteristic of the image using point source. Satellite image from Korea Multi-purpose Satellite 2 (KOMPSAT-2) also requires Modular Transfer Function (MTF) compensation process to achieve more realistic image which entails removing ringing artifacts at the edges and restraining excess use of denoising eect in order to keep it more realistic. This paper focuses on the deconvolution of KOMPSAT-2 image utilizing PSF attained from Korea Aerospace Research Institute compared to deconvolution with the estimated PSF blur kernel. The deconvolution algorithm considered are Richard-Lucy, Damped Richard-Lucy, Bilateral Richard-Lucy and Sparse Prior deconvolution algorithms.

Lee, Jihye; Chun, Joohwan; Lee, Donghwan

2012-05-01

40

Genetic algorithms for optimal reactive power compensation planning on the national grid system  

NASA Astrophysics Data System (ADS)

This work investigates the use of Genetic Algorithms (GAs) for optimal Reactive power Compensation Planning (RCP) of practical power systems. In particular, RCP of the transmission system of England and Wales as owned and operated by National Grid is considered. The GA is used to simultaneously solve both the siting problem---optimisation of the installation of new devices---and the operational problem---optimisation of preventive transformer taps and the controller characteristics of dynamic compensation devices. A computer package called Genetic Compensation Placement (GCP) has been developed which uses an Integer coded GA (IGA) to solve the RCP problem. The RCP problem is implemented as a multi-objective optimisation: in the interests of security, the number of system and operational constraint violations and the deviation of the busbar voltages from the ideal are all minimised for the base (intact) case and the contingent cases. In the interests of cost reduction, the reactive power cost is minimised for the base case. The reactive power cost encompasses the costs incurred from the installation of reactive power sources and the utilisation of new and existing dynamic reactive power compensation devices. GCP is compared to SCORPION (a planning program currently being used by National Grid) which uses a combination of linear programming and heuristic back-tracking. Results are presented for a practical test system developed with the cooperation of National Grid, and it is found that GCP produces solutions that are cheaper than solutions found by SCORPION and perform extremely well: an improvement in voltage profiles, a decrease in complex power mismatches, and a reduction in MVolt Amps-reactive (VAr) utilisation were observed.

Pilgrim, J. D.

41

Fast variable-block-size motion compensation algorithm for H.264 video coding  

NASA Astrophysics Data System (ADS)

The emerging H.264 video coding Standard can achieve a substantial coding gain as compared with existing coding standards. One major contribution of its gain comes from a very rich syntax for motion compensated prediction at the expense of a higher computational complexity. To be more specific, seven modes of different block sizes and shapes (i.e. 16x16, 16x8, 8x16, 8x8, 8x4, 4x8 and 4x4) are supported. To do full search over all modes requires an extremely large amount of computation. We propose a fast search algorithm for the variable block size motion estimation. The proposed algorithm includes three stages. First, an initial estimate of the motion vector is obtained by a multi-resolution motion search. Then, based on the estimated motion vector and its corresponding distortion measure, a rate-distortion model is used to select the initial mode for motion search. Finally, some early-termination rules are adopted to reject impossible block sizes and motion locatios sooner. By avoiding search through all block sizes, the amount of computation involved in the motion search can be substantially reduced. The proposed algorithm can achieve a speed-up factor up to 120 times when compared to the fastest full-search algorithm.

Kuo, Chih-Hung; Shen, Meiyin; Kuo, C.-C. Jay

2003-11-01

42

A two-stage lossless compression algorithm for aurora image using weighted motion compensation and context-based model  

NASA Astrophysics Data System (ADS)

Addressing the transmission and storage problems of aurora images that Arctic Yellow River Station of China faces, the present paper proposes a two-stage lossless compression algorithm based on weighted motion compensation and context-based modeling. As no specialized compression algorithms for aurora images are available, proposing a new algorithm that offers a satisfactory lossless compression performance for aurora images is necessary. The proposed algorithm utilizes the weighted motion compensation to obtain the motion vector based on the unusual movement characteristics of aurora images. Subsequently, the context-based model is combined with the motion vector. Experimental results indicated that the proposed algorithm outperformed the state-of-the-art lossless compression methods.

Wu, Jiaji; Liang, Chong; Han, Jianxiang; Hu, Zejun; Huang, Dehong; Hu, Hongqiao; Fang, Yong; Jiao, Licheng

2013-03-01

43

Algorithm for atmospheric corrections of aircraft and satellite imagery  

Microsoft Academic Search

An algorithm is described for making fast atmospheric corrections. The required radiation parameters are stored in a lookup table. The procedure is to enter the lookup table with the measured radiance, wavelength, view and illumination directions, heights of observation and surface, and the aerosol and gaseous absorption optical thicknesses. The surface radiance, the irradiance incident on a surface, and surface

R. S. FRASER; R. A. FERRARE; Y. J. KAUFMAN; B. L. MARKHAM; S. MATTOO

1992-01-01

44

Multiangle Implementation of Atmospheric Correction (MAIAC): 2. Aerosol Algorithm  

NASA Technical Reports Server (NTRS)

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 reflectance. The aerosol algorithm derives the spectral regression coefficient (SRC) relating surface bidirectional reflectance in the blue (0.47 micron) and shortwave infrared (2.1 micron) bands; this quantity is prescribed in the MODIS operational Dark Target algorithm based on a parameterized formula. The MAIAC aerosol products include aerosol optical thickness and a fine-mode fraction at resolution of 1 km. This high resolution, required in many applications such as air quality, brings new information about aerosol sources and, potentially, their strength. AERONET validation shows that the MAIAC and MOD04 algorithms have similar accuracy over dark and vegetated surfaces and that MAIAC generally improves accuracy over brighter surfaces due to the SRC retrieval and explicit bidirectional reflectance factor characterization, as demonstrated for several U.S. West Coast AERONET sites. Due to its generic nature and developed angular correction, MAIAC performs aerosol retrievals over bright deserts, as demonstrated for the Solar Village Aerosol Robotic Network (AERONET) site in Saudi Arabia.

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

2011-01-01

45

Finite element-wavelet hybrid algorithm for atmospheric tomography.  

PubMed

Reconstruction of the refractive index fluctuations in the atmosphere, or atmospheric tomography, is an underlying problem of many next generation adaptive optics (AO) systems, such as the multiconjugate adaptive optics or multiobject adaptive optics (MOAO). The dimension of the problem for the extremely large telescopes, such as the European Extremely Large Telescope (E-ELT), suggests the use of iterative schemes as an alternative to the matrix-vector multiply (MVM) methods. Recently, an algorithm based on the wavelet representation of the turbulence has been introduced in [Inverse Probl.29, 085003 (2013)] by the authors to solve the atmospheric tomography using the conjugate gradient iteration. The authors also developed an efficient frequency-dependent preconditioner for the wavelet method in a later work. In this paper we study the computational aspects of the wavelet algorithm. We introduce three new techniques, the dual domain discretization strategy, a scale-dependent preconditioner, and a ground layer multiscale method, to derive a method that is globally O(n), parallelizable, and compact with respect to memory. We present the computational cost estimates and compare the theoretical numerical performance of the resulting finite element-wavelet hybrid algorithm with the MVM. The quality of the method is evaluated in terms of an MOAO simulation for the E-ELT on the European Southern Observatory (ESO) end-to-end simulation system OCTOPUS. The method is compared to the ESO version of the Fractal Iterative Method [Proc. SPIE7736, 77360X (2010)] in terms of quality. PMID:24690653

Yudytskiy, Mykhaylo; Helin, Tapio; Ramlau, Ronny

2014-03-01

46

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

47

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

48

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

49

An Improved Method of Heterogeneity Compensation for the Convolution / Superposition Algorithm  

NASA Astrophysics Data System (ADS)

Purpose: To improve the accuracy of convolution/superposition (C/S) in heterogeneous material by developing a new algorithm: heterogeneity compensated superposition (HCS). Methods: C/S has proven to be a good estimator of the dose deposited in a homogeneous volume. However, near heterogeneities electron disequilibrium occurs, leading to the faster fall-off and re-buildup of dose. We propose to filter the actual patient density in a position and direction sensitive manner, allowing the dose deposited near interfaces to be increased or decreased relative to C/S. We implemented the effective density function as a multivariate first-order recursive filter and incorporated it into GPU-accelerated, multi-energetic C/S implementation. We compared HCS against C/S using the ICCR 2000 Monte-Carlo accuracy benchmark, 23 similar accuracy benchmarks and 5 patient cases. Results: Multi-energetic HCS increased the dosimetric accuracy for the vast majority of voxels; in many cases near Monte-Carlo results were achieved. We defined the per-voxel error, %|mm, as the minimum of the distance to agreement in mm and the dosimetric percentage error relative to the maximum MC dose. HCS improved the average mean error by 0.79 %|mm for the patient volumes; reducing the average mean error from 1.93 %|mm to 1.14 %|mm. Very low densities (i.e. < 0.1 g / cm3) remained problematic, but may be solvable with a better filter function. Conclusions: HCS improved upon C/S's density scaled heterogeneity correction with a position and direction sensitive density filter. This method significantly improved the accuracy of the GPU based algorithm reaching the accuracy levels of Monte Carlo based methods with performance in a few tenths of seconds per beam. Acknowledgement: Funding for this research was provided by the NSF Cooperative Agreement EEC9731748, Elekta / IMPAC Medical Systems, Inc. and the Johns Hopkins University. James Satterthwaite provided the Monte Carlo benchmark simulations.

Jacques, Robert; McNutt, Todd

2014-03-01

50

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

51

The Atmospheric Compensation Component of a Landsat Land Surface Temperature (LST) Product: Assessment of Errors Expected for a North American Test Product  

NASA Astrophysics Data System (ADS)

The Landsat archive of thermal data (Landsats 4, 5 and 7) has gone through a rigorous calibration assessment and update. However, in order to be useful to most users the calibrated sensor reaching radiance must be corrected to surface temperatures by first compensating for atmospheric effects and then emissivity variations. The USGS is exploring the possibility of producing a LST product through a joint program with RIT (the atmospheric compensation component) and JPL (the emissivity compensation component). This paper addresses the atmospheric compensation component for an initial North American pilot study. In particular, the results of a comparison of retrieved water surface temperature (where emissivity is well known) and truth temperatures for over 800 sites are presented. The errors are broken down by cloud conditions with extremely good results for cloud-free conditions (errors less than 1 K). The results of the error assessment for North America by cloud class are presented along with a discussion of potential quality data for a LST product. An initial assessment of the LST errors observed for Landsat 8 bands 10 and 11 are also presented. The next steps on this effort include testing of a global atmospheric compensation approach and full integration of the atmospheric and emissivity compensation tools into an operational LST product.

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

2014-11-01

52

Phase measurement and error analysis in the arc-tangent method using a novel phase-compensating algorithm  

NASA Astrophysics Data System (ADS)

Many applications related to measurements use sinusoidal waves such as acoustic and electromagnetic waves. In particular, the phase information of sinusoidal waves is frequently used in several sensors. However, it is difficult to extract the phase information exactly, and many operations are consequently demanded. Among the operations, the arc-tangent method is very useful to measure the phase of a sinusoidal signal. This method, however, has a limitation that the initial phase difference between two sinusoidal signals must be essentially 90°, in some cases preventing its use. This paper proposes a novel algorithm to calculate the initial phase difference between two sinusoidal signals and to compensate the initial phase difference to exactly 90°. Several mathematical steps including equations are taken for the compensation. The mathematical equations are successfully simulated by using a numerical method to verify their availability in a computer simulation. In addition, experimental verification is also shown to confirm the performance of the algorithm by using a function generator and a data acquisition system. Finally, the phase measurement is also successfully performed by using the phase-compensating algorithm and the error of the phase measurement is analyzed.

Kim, Dae-Hyun; Ahn, Byung-Jun

2013-10-01

53

Evaluation of atmospheric thermal radiation algorithms for daylight hours  

NASA Astrophysics Data System (ADS)

Existing simple but theoretically based clear-sky models for longwave down-welling radiation (LDRc) and cloud impact algorithms transforming them to all-sky radiation (LDR) are checked against locally calibrated empirical algorithms. They are evaluated for daylight hours based on measurements in regionally differing climates of Germany. The Prata clear-sky scheme is additionally tested with adjusted coefficients so that LDRc converges against a realistic emissivity for a completely dry atmosphere. This version is characterised by an improved modelled variance. Compared with locally calibrated schemes, bias and root mean square error (RMSE) of the more theoretical clear-sky schemes do not differ significantly and yield even better results at a mountain site. In contrast, the locally calibrated algorithms yield biases up to 9% and an increase in RMSE between 6% and 67%, if applied for other sites. For daylight hours, the cloud impact on LDR can be calculated via the ratio of observed to clear-sky global irradiation (CMFsol). With CMFsol, the Crawford and Duchon scheme reveals the lowest bias and a decrease in RMSE by 22% against the next best performing algorithms. Compared with synoptic cloud observations as input, the bias is reduced by 9 to 28 W m-2 and the scattering of the residuals decreases by 20% to 30%. Based on published results for also non-European sites, it is inferred that the more theoretically based LDRc schemes and cloud impact evaluated via CMFsol are universally applicable and perform at least in the order of magnitude of locally calibrated empirical algorithms.

Staiger, Henning; Matzarakis, Andreas

2010-10-01

54

Precision laser surveying instrument using atmospheric turbulence compensation by determining the absolute displacement between two laser beam components  

DOEpatents

Atmospheric effects on sighting measurements are compensated for by adjusting any sighting measurements using a correction factor that does not depend on atmospheric state conditions such as temperature, pressure, density or turbulence. The correction factor is accurately determined using a precisely measured physical separation between two color components of a light beam (or beams) that has been generated using either a two-color laser or two lasers that project different colored beams. The physical separation is precisely measured by fixing the position of a short beam pulse and measuring the physical separation between the two fixed-in-position components of the beam. This precisely measured physical separation is then used in a relationship that includes the indexes of refraction for each of the two colors of the laser beam in the atmosphere through which the beam is projected, thereby to determine the absolute displacement of one wavelength component of the laser beam from a straight line of sight for that projected component of the beam. This absolute displacement is useful to correct optical measurements, such as those developed in surveying measurements that are made in a test area that includes the same dispersion effects of the atmosphere on the optical measurements. The means and method of the invention are suitable for use with either single-ended systems or a double-ended systems.

Veligdan, James T. (Manorville, NY)

1993-01-01

55

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

2015-01-01

56

Hyperspectral image lossless compression algorithm based on error compensated prediction tree of multi-band prediction  

NASA Astrophysics Data System (ADS)

A new lossless compression method based on prediction tree with error compensation for hyperspectral imagery is proposed in this paper. This method incorporates the techniques of prediction tree and adaptive band prediction. The proposed method is different from previous similar approaches in that its prediction to the current band is performed by multiple bands and the error created by the prediction tree is compensated by a linear adaptive predictor for decorrelating spectral statistical redundancy. After de-correlating intraband and interband redundancy, the SPIHT (Set Partitioning in Hierarchical Trees) wavelet coding is used to encode the residual image. The proposed method achieves high compression ratio on the NASA JPL AVIRIS data.

Wang, Lang; Guo, Shuxu; Gu, Lingjia; Ren, Ruizhi

2008-08-01

57

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

58

Improvements of Transform Coding Algorithm for Motion-Compensated Interframe Prediction Errors-DCT\\/SQ Coding  

Microsoft Academic Search

A new hybrid coding method for transmitting videoconferencing images at a bit rate 384 kbits\\/s is proposed. Considering the characteristics of motion-compensated interframe prediction errors for typical videoconferencing scenes, a filter is introduced to separate pulsive components on which conventional discrete cosine transform (DCT) coding method does not work well. These separated pulsive components are coded by using scalar quantization

MASAHIDE KANEKO; YOSHINORI HATORI; ATSUSHI KOIKE

1987-01-01

59

Hyperspectral image lossless compression algorithm based on error compensated prediction tree of multi-band prediction  

Microsoft Academic Search

A new lossless compression method based on prediction tree with error compensation for hyperspectral imagery is proposed in this paper. This method incorporates the techniques of prediction tree and adaptive band prediction. The proposed method is different from previous similar approaches in that its prediction to the current band is performed by multiple bands and the error created by the

Lang Wang; Shuxu Guo; Lingjia Gu; Ruizhi Ren

2008-01-01

60

Design of error-compensating algorithms for sinusoidal phase shifting interferometry  

SciTech Connect

An improved approach to interferometry using sinusoidal phase shifting balances several harmonic components in the interference signal against each other. The resulting computationally efficient phase-estimation algorithms have low sensitivity to errors such as spurious intensity noise, vibration, and errors in the phase shift pattern. Specific example algorithms employing 8 and 12 camera frames illustrate design principles that are extendable to algorithms of any length for applications that would benefit from a simplified, sinusoidal phase shift.

Groot, Peter de

2009-12-10

61

Method for designing error-compensating phase-calculation algorithms for phase-shifting interferometry.  

PubMed

We propose a general approach to eliminating some error source effects in phase-calculation algorithms for phase-shifting interferometry. We express the actual phase shift in a convenient form that takes the errors into account and develop in series the detected phase from a generic algorithm. Setting to zero the terms of the series that involve unwanted errors leads to a set of linear equations for the algorithm coefficients, which can thus be found. By using this approach, one could develop an algorithm series for an individual interferometer based on relevant concerns about the main error sources in it and eliminate the error source effects to any desired order. Two examples of algorithm series, to eliminate distorted phase shifts caused by the geometric effect in an interferometer with a spherical Fizeau cavity and to eliminate vibration effects, are discussed. PMID:18360495

Zhu, Y; Gemma, T

2001-09-01

62

Restoration of atmospheric turbulence degraded video using kurtosis minimization and motion compensation  

NASA Astrophysics Data System (ADS)

It has been long recognized that atmospheric turbulence degrades the quality of images and video sequences. Stationary objects being observed through the atmosphere can appear blurred and waver spatially as if they are in motion. This phe- nomenon is well recognized, especially in astronomy. The degradation arises from the complicated, random fluctuations in the refractive index of the air, caused by fluctuations in temperature. In this thesis, the fundamental theory of turbulence such as the Kolmogorov law is reviewed. It is also shown that the point spread function (PSF) of the turbulence can be derived from the physics equations that describe atmospheric turbulence. Atmospheric turbulence degradation is usually modeled as a linear convolution. The turbulence is dynamic and random in nature. The blurring parameter of the PSF of the turbulence is dependent on altitude, temperature, the rate of energy per mass dissipated by viscous friction, the sheer rate of the wind, and soon. Information about those turbulence conditions is often not available. Thus, the exact PSF of the turbulence blur is generally unknown in practice. Consequentially, blind image deconvolution technique is used in such a context. Blind image deconvolution is well known to be an ill-posed problem. Certain assumptions about the image and/or the blur must be made in order to find a solution. It has been observed that the kurtosis of the blurred (smoothed) image is often higher than an unblurred version. This observation is studied and justified using a frequency domain analysis where kurtosis is first represented and then interpreted. An image can be decomposed into a low frequency component and a high frequency component. It is found that the kurtosis of an image is dominated by the interaction of the low frequency and high frequency components. Blurring alters the interaction and tends to increase the kurtosis. In addition to the theoretical analysis, experiments are conducted to verify that the smoothed image has higher kurtosis. This important observation forms the basis for the new blind deconvolution method. Kurtosis can be viewed as a metric to measure the quality of the resorted image without having the original image. In simulations, when an original image is available, one can use peak signal-to-noise ratio (PSNR), to determine the restored image that has the highest PSNR (PSNR maximization) to estimate the blurring parameter. Kurtosis minimization based blur identification works as following given the functional form of the blur and an estimate of the parameter space, the parameter is searched by minimizing the kurtosis of the restored image. The restored image that has minimal kurtosis is used as the final estimate of the true image and the corresponding parameter is the identified blurring parameter. In many simulations, kurtosis minimization gives the same result as PSNR maximization. Kurtosis minimization is a generally applicable blur identification method. It has been tested on a variety of blurs including Gaussian blur, linear motion blur, out-of-focus blur, averaging blur and atmospheric turbulence blurs. In many experiments on standard test images, kurtosis minimization is able to give perfect estimation at different levels of noise. Moreover, it is compared with generalized cross validation (GCV) based blur identification on atmospheric turbulence blurs, which is the main application in this thesis work. Besides blurring, turbulence also introduces geometric distortion in the video since the turbulence is time-varying. (Abstract shortened by UMI.)

Li, Dalong

2007-08-01

63

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

64

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

65

Multichannel optical PMD compensator  

NASA Astrophysics Data System (ADS)

We report for the first time a multichannel in-line PMD compensator which independently provides higher-order PMD compensation for each DWDM channel in the C band. Feedforward compensation is implemented through a robust optimization algorithm using high-speed, high-resolution spectral polarimetric data for each channel. Both 10 and 40 Gb/sec 40-channel 100-GHz compensators are reported, and extensive test results over a range of second-order PMD conditions are presented.

Targove, James D.; Wein, Steven J.; Menikoff, Arthur; Cahill, Michael J. L.; Yang, Sheng-Hui

2004-10-01

66

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

67

Comparison of atmospheric correction algorithms for TM image in inland waters  

Microsoft Academic Search

In order to extract quantitative water?leaving information from the Thematic Mapper (TM) image accurately in inland waters, atmospheric correction is a necessary step. Based on former researchers' results, the paper presents two atmospheric correction algorithms based on meteorological data (MD) and on Moderate Resolution Imaging Spectroradiometer (MODIS) Vicarious Calibration (MVC) for TM image in inland waters according to the theory

Shaoqi Gong; Jiazhu Huang; Yunmei Li; Haijun Wang

2008-01-01

68

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 laptop—a 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

69

An ultrasonic transducer transient compensator design based on a simplified Variable Structure Control algorithm.  

PubMed

A non-linear control method, known as Variable Structure Control (VSC), is employed to reduce the duration of ultrasonic (US) transducer transients. A physically realizable system using a simplified form of the VSC algorithm is proposed for standard piezoelectric transducers and simulated. Results indicate a VSC-controlled transmitter reduces the transient duration to less than a carrier wave cycle. Applications include high capacity ultrasound communication and localization systems. PMID:23993746

Ma, Shaodong; Wilkinson, Antony J; Paulson, Kevin S

2014-02-01

70

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

71

Compensation algorithm for the phase-shift error of polarization-based parallel two-step phase-shifting digital holography.  

PubMed

We propose an algorithm for compensating the phase-shift error of polarization-based parallel two-step phase-shifting digital holography, which is a technique for recording a spatial two-step phase-shifted hologram. Although a polarization-based system of the technique has been experimentally demonstrated, there had been the problem that the phase difference of two phase-shifted holograms had been changed by the extinction ratio of the micropolarizer array attached to the image sensor used in the system. To improve the performance of the system, we established and formulated an algorithm for compensating the phase-shift error. Accurate spatial phase-shifting interferometry in the system can be conducted by the algorithm regardless of phase-shift error due to the extinction ratio. By the numerical simulation, the proposed algorithm was capable of reducing the root mean square errors of the reconstructed image by 1/4 and 1/5 in amplitude and phase, respectively. Also, the algorithm was experimentally demonstrated, and the experimental results showed that the system employing the proposed algorithm suppressed the conjugate image, which slightly appeared in the image reconstructed by the system not employing the algorithm, even when the extinction ratio was 10:1. Thus, the effectiveness of the proposed algorithm was numerically and experimentally verified. PMID:21364709

Tahara, Tatsuki; Ito, Kenichi; Kakue, Takashi; Fujii, Motofumi; Shimozato, Yuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

2011-03-01

72

A fast CT and CT-fluoroscopy registration algorithm with respiratory motion compensation for image-guided lung intervention.  

PubMed

CT-fluoroscopy (CTF) is an efficient imaging technique for guiding percutaneous lung intervention such as biopsy and ablation. In CTF-guided procedures, four to ten axial images are captured in a very short time period during breath holding to provide near real-time feedback of patients' anatomy so that physicians can adjust the needle as it is advanced toward a target lesion. Although popularly used in clinics, this procedure requires frequent scans to guide the needle, which may cause increased procedure time, complication rates, and radiation exposure to both clinicians and patients. In addition, CTF only generates a limited number of 2-D axial images and does not provide sufficient 3-D anatomical information. Therefore, how to provide volumetric anatomical information using CTF while reducing intraoperative scan is an important and challenging problem. In this paper, we propose a fast CT-CTF deformable registration algorithm that warps the inhale preprocedural CT onto the intraprocedural CTF for guidance in 3-D. In the algorithm, the deformation in the transverse plane is modeled using 2-D B-Spline, and the deformation along z-direction is regularized by smoothness constraint. A respiratory motion compensation framework is also incorporated for accurate registration. A parallel implementation strategy is adopted to accomplish the registration in several seconds. With electromagnetic tracking, the needle position can be superimposed onto the deformed inhale CT image, thereby providing 3-D image guidance during breath holding. Experiments were conducted using both simulated CTF images with known deformation and real CTF images captured during lung cancer biopsy studies. The experiments demonstrated satisfactory registration results of our proposed fast CT-CTF registration algorithm. PMID:23434600

Su, Po; Yang, Jianhua; Lu, Kongkuo; Yu, Nam; Wong, Stephen T; Xue, Zhong

2013-07-01

73

Real-time design and simulation of an actuator failure compensation algorithm for a rocket fairing vibration reduction model  

Microsoft Academic Search

Active vibration control for a rocket fairing system requires tight timing constraints to guarantee desired system real-time performance. Actuator failures can cause performance deterioration or dysfunction of a fairing system, which needs to be effectively compensated in a timely manner. In this paper, the actuator failure compensation problem is formulated and an adaptive actuator failure compensation scheme is evaluated for

Lingfeng Wang; Gang Tao; John A. Stankovic; Xidong Taiig

2003-01-01

74

S. 2466: This Act may be cited as the National Atmospheric Nuclear Testing Compensation Act of 1990. Introduced in the Senate of the United States, One Hundredth First Congress, Second Session, April 19, 1990  

SciTech Connect

This bill would amend Title XXI of the Public Health Service Act to provide for the establishment of an atmospheric nuclear testing compensation program to compensate civilians living down wind of the Nevada Test Site during above-ground testing of nuclear weapons and miners exposed in underground uranium mines supplying uranium for the primary use and benefit of the nuclear weapons program. The bill describes technical assistance and information, administrative procedures for filing a petition, determination of eligibility, and amount of compensation.

Not Available

1990-01-01

75

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

76

Brightness-compensated 3-D optical flow algorithm for monitoring cochlear motion patterns  

NASA Astrophysics Data System (ADS)

A method for three-dimensional motion analysis designed for live cell imaging by fluorescence confocal microscopy is described. The approach is based on optical flow computation and takes into account brightness variations in the image scene that are not due to motion, such as photobleaching or fluorescence variations that may reflect changes in cellular physiology. The 3-D optical flow algorithm allowed almost perfect motion estimation on noise-free artificial sequences, and performed with a relative error of <10% on noisy images typical of real experiments. The method was applied to a series of 3-D confocal image stacks from an in vitro preparation of the guinea pig cochlea. The complex motions caused by slow pressure changes in the cochlear compartments were quantified. At the surface of the hearing organ, the largest motion component was the transverse one (normal to the surface), but significant radial and longitudinal displacements were also present. The outer hair cell displayed larger radial motion at their basolateral membrane than at their apical surface. These movements reflect mechanical interactions between different cellular structures, which may be important for communicating sound-evoked vibrations to the sensory cells. A better understanding of these interactions is important for testing realistic models of cochlear mechanics.

von Tiedemann, Miriam; Fridberger, Anders; Ulfendahl, Mats; de Monvel, Jacques Boutet

2010-09-01

77

Assessment, Validation, and Refinement of the Atmospheric Correction Algorithm for the Ocean Color Sensors. Chapter 19  

NASA Technical Reports Server (NTRS)

The primary focus of this proposed research is for the atmospheric correction algorithm evaluation and development and satellite sensor calibration and characterization. It is well known that the atmospheric correction, which removes more than 90% of sensor-measured signals contributed from atmosphere in the visible, is the key procedure in the ocean color remote sensing (Gordon and Wang, 1994). The accuracy and effectiveness of the atmospheric correction directly affect the remotely retrieved ocean bio-optical products. On the other hand, for ocean color remote sensing, in order to obtain the required accuracy in the derived water-leaving signals from satellite measurements, an on-orbit vicarious calibration of the whole system, i.e., sensor and algorithms, is necessary. In addition, it is important to address issues of (i) cross-calibration of two or more sensors and (ii) in-orbit vicarious calibration of the sensor-atmosphere system. The goal of these researches is to develop methods for meaningful comparison and possible merging of data products from multiple ocean color missions. In the past year, much efforts have been on (a) understanding and correcting the artifacts appeared in the SeaWiFS-derived ocean and atmospheric produces; (b) developing an efficient method in generating the SeaWiFS aerosol lookup tables, (c) evaluating the effects of calibration error in the near-infrared (NIR) band to the atmospheric correction of the ocean color remote sensors, (d) comparing the aerosol correction algorithm using the singlescattering epsilon (the current SeaWiFS algorithm) vs. the multiple-scattering epsilon method, and (e) continuing on activities for the International Ocean-Color Coordinating Group (IOCCG) atmospheric correction working group. In this report, I will briefly present and discuss these and some other research activities.

Wang, Menghua

2003-01-01

78

A real-time algorithm for atmospheric corrections of airborne remote optical measurements above the ocean  

SciTech Connect

The approximate solution to the equation of transfer for optical radiation in the atmosphere above the sea is obtained. For a zeroth approximation derivation of the equation of transfer, a bi-transport representation of the light scattering phase function was used. Already in this approximation an equation for the transmittance of the atmosphere is obtained within an accuracy of about 5%. The next approximation leads to expressions for radiance factors of the sky and ocean-atmospheric-layer system, the latter of which, in the case of an homogeneous atmosphere and not very oblique sensing and solar angles, transforms at the upper boundary of the atmosphere into the well-known formulae used for processing optical satellite data. The results of this study can be used to develop algorithms for processing airborne and shipborne optical information. 5 refs.

Haltrin, V.I. [Naval Research Lab., Stennis Space Center, MS (United States)

1996-11-01

79

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

80

S. 1994: This Act may be cited as the National Atmospheric Nuclear Testing Compensation Act of 1989. Introduced in the Senate of the United States, One Hundredth First Congress, First Session, November 22, 1989  

SciTech Connect

This bill would amend Title XXI of the Public Health Service Act to provide for the establishment of an atmospheric nuclear testing compensation program to compensate for the damages done to the civilians in Nevada, Utah, and Arizona down wind from the above-ground nuclear tests in Nevada and to exposed miners in underground uranium mines that were providing uranium for the sole use and benefit of the nuclear weapons program of the US. The bill explains how to file a petition for compensation, the determination of eligibility, and the amount that can be claimed.

Not Available

1989-01-01

81

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

82

Adaptation of a Hyperspectral Atmospheric Correction Algorithm for Multi-spectral Ocean Color Data in Coastal Waters. Chapter 3  

NASA Technical Reports Server (NTRS)

This SIMBIOS contract supports several activities over its three-year time-span. These include certain computational aspects of atmospheric correction, including the modification of our hyperspectral atmospheric correction algorithm Tafkaa for various multi-spectral instruments, such as SeaWiFS, MODIS, and GLI. Additionally, since absorbing aerosols are becoming common in many coastal areas, we are making the model calculations to incorporate various absorbing aerosol models into tables used by our Tafkaa atmospheric correction algorithm. Finally, we have developed the algorithms to use MODIS data to characterize thin cirrus effects on aerosol retrieval.

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

2003-01-01

83

Retrieving Atmospheric Temperature and Moisture Profiles from NPP CRIS/ATMS Sensors Using Crimss EDR Algorithm  

NASA Technical Reports Server (NTRS)

The Joint Polar Satellite System (JPSS) is a U.S. National Oceanic and Atmospheric Administration (NOAA) mission in collaboration with the U.S. National Aeronautical Space Administration (NASA) and international partners. The NPP Cross-track Infrared Microwave Sounding Suite (CrIMSS) consists of the infrared (IR) Crosstrack Infrared Sounder (CrIS) and the microwave (MW) Advanced Technology Microwave Sounder (ATMS). The CrIS instrument is hyperspectral interferometer, which measures high spectral and spatial resolution upwelling infrared radiances. The ATMS is a 22-channel radiometer similar to Advanced Microwave Sounding Units (AMSU) A and B. It measures top of atmosphere MW upwelling radiation and provides capability of sounding below clouds. The CrIMSS Environmental Data Record (EDR) algorithm provides three EDRs, namely the atmospheric vertical temperature, moisture and pressure profiles (AVTP, AVMP and AVPP, respectively), with the lower tropospheric AVTP and the AVMP being JPSS Key Performance Parameters (KPPs). The operational CrIMSS EDR an algorithm was originally designed to run on large IBM computers with dedicated data management subsystem (DMS). We have ported the operational code to simple Linux systems by replacing DMS with appropriate interfaces. We also changed the interface of the operational code so that we can read data from both the CrIMSS science code and the operational code and be able to compare lookup tables, parameter files, and output results. The detail of the CrIMSS EDR algorithm is described in reference [1]. We will present results of testing the CrIMSS EDR operational algorithm using proxy data generated from the Infrared Atmospheric Sounding Interferometer (IASI) satellite data and from the NPP CrIS/ATMS data.

Liu, X.; Kizer, S.; Barnet, C.; Dvakarla, M.; Zhou, D. K.; Larar, A. M.

2012-01-01

84

Algorithm for Atmospheric and Glint Corrections of Satellite Measurements of Ocean Pigment  

NASA Technical Reports Server (NTRS)

An algorithm is developed to correct satellite measurements of ocean color for atmospheric and surface reflection effects. The algorithm depends on taking the difference between measured and tabulated radiances for deriving water-leaving radiances. 'ne tabulated radiances are related to the measured radiance where the water-leaving radiance is negligible (670 nm). The tabulated radiances are calculated for rough surface reflection, polarization of the scattered light, and multiple scattering. The accuracy of the tables is discussed. The method is validated by simulating the effect of different wind speeds than that for which the lookup table is calculated, and aerosol models different from the maritime model for which the table is computed. The derived water-leaving radiances are accurate enough to compute the pigment concentration with an error of less than q 15% for wind speeds of 6 and 10 m/s and an urban atmosphere with aerosol optical thickness of 0.20 at lambda 443 nm and decreasing to 0.10 at lambda 670 nm. The pigment accuracy is less for wind speeds less than 6 m/s and is about 30% for a model with aeolian dust. On the other hand, in a preliminary comparison with coastal zone color scanner (CZCS) measurements this algorithm and the CZCS operational algorithm produced values of pigment concentration in one image that agreed closely.

Fraser, Robert S.; Mattoo, Shana; Yeh, Eueng-Nan; McClain, C. R.

1997-01-01

85

The Computational Complexity, Parallel Scalability, and Performance of Atmospheric Data Assimilation Algorithms  

NASA Technical Reports Server (NTRS)

The computational complexity of algorithms for Four Dimensional Data Assimilation (4DDA) at NASA's Data Assimilation Office (DAO) is discussed. In 4DDA, observations are assimilated with the output of a dynamical model to generate best-estimates of the states of the system. It is thus a mapping problem, whereby scattered observations are converted into regular accurate maps of wind, temperature, moisture and other variables. The DAO is developing and using 4DDA algorithms that provide these datasets, or analyses, in support of Earth System Science research. Two large-scale algorithms are discussed. The first approach, 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 similar to global meteorological weather forecasting data assimilation systems, but is used at NASA for climate research. Systems of this size typically run at between 1 and 20 gigaflop/s. The second approach, the Kalman filter, uses a more consistent algorithm to determine the forecast error covariance matrix than does GEOS DAS. For atmospheric assimilation, the gridded dynamical fields typically have More than 10(exp 6) variables, therefore the full error covariance matrix may be in excess of a teraword. For the Kalman filter this problem can easily scale to petaflop/s proportions. We discuss the computational complexity of GEOS DAS and our implementation of the Kalman filter. We also discuss and quantify some of the technical issues and limitations in developing efficient, in terms of wall clock time, and scalable parallel implementations of the algorithms.

Lyster, Peter M.; Guo, J.; Clune, T.; Larson, J. W.; Atlas, Robert (Technical Monitor)

2001-01-01

86

A procedure for testing the quality of LANDSAT atmospheric correction algorithms  

NASA Technical Reports Server (NTRS)

There are two basic methods for testing the quality of an algorithm to minimize atmospheric effects on LANDSAT imagery: (1) test the results a posteriori, using ground truth or control points; (2) use a method based on image data plus estimation of additional ground and/or atmospheric parameters. A procedure based on the second method is described. In order to select the parameters, initially the image contrast is examined for a series of parameter combinations. The contrast improves for better corrections. In addition the correlation coefficient between two subimages, taken at different times, of the same scene is used for parameter's selection. The regions to be correlated should not have changed considerably in time. A few examples using this proposed procedure are presented.

Dias, L. A. V. (principal investigator); Vijaykumar, N. L.; Neto, G. C.

1982-01-01

87

Compensation of aberration distortions of a laser beam wavefront in the bistatic location scheme  

NASA Astrophysics Data System (ADS)

The possibility of compensating for aberration distortions in the wavefront of a pulse laser beam by use of the backscatter signal in the atmosphere in the bistatic location scheme is studied numerically. It is shown that, as in the case of the monostatic location scheme, using the bistatic scheme permits one, under certain conditions, to significantly compensate for aberrations using a flexible mirror and apply the algorithm of backscatter signal maximization. An increase in the aperture of the receiving telescope makes it possible to considerably increase the signal-to-noise ratio and, owing to this, compensate for aberrations at a lesser energy of the probing pulse.

Banakh, V. A.; Smalikho, I. N.

2014-12-01

88

A new raytracing algorithm to compute slant total delays in a mesoscale atmospheric model  

NASA Astrophysics Data System (ADS)

Ray-tracing is essential to accurately simulate Global Positioning System (GPS) Slant Total Delays (STD) in a mesoscale atmospheric model. A rigorous ray-tracing algorithm based on Fermat's principle was developed to simulate the propagation of radio signals in a gridded 3D refractivity field. The unique in the proposed algorithm is that the solution automatically involves the exact location of the receiver and the satellite, i.e. 'shooting' is not required. The structured non-linear system of equations, arising due to the applied finite difference scheme, is solved by Newton's iteration. For elevation angles as low as 5 degree at a ground-based receiver a single Newton iteration turns out to be sufficient. Subsequently the algorithm allows us to simulate about 1500 STDs per second on a single CPU. Having developed the forward operator for STDs, we constructed the tangent linear and adjoint code for sensitivity and variational data analysis. First results from three potential applications of the proposed ray-tracing algorithm are presented: (1) monitoring STD data processed at the GFZ Potsdam against European Centre for Medium-Range Weather Forecasts (ECMWF) analysis, (2) vertical profiling, i.e. the retrieval of the refractivity profile above a ground based receiver from the STD data by using a least square adjustment, and (3) direct mapping.

Zus, Florian; Bender, Michael; Dick, Galina; Deng, Zhiguo; Heise, Stefan; Wickert, Jens

2010-05-01

89

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

90

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

91

Atmospheric correction for ocean colour images using a classification and a neuro-variational algorithm  

NASA Astrophysics Data System (ADS)

Radiometers on board satellite measure the solar radiation reflected by both ocean and atmosphere at several wavelengths. One difficulty is that the signal is strongly polluted by the contribution of the atmosphere. An important step in the processing of ocean colour images is the so-called "atmospheric correction" that consists in removing the contribution of the atmospheric signal to solely retrieve the ocean contribution. Due to the presence of aerosols in the atmosphere, this contribution cannot be predicted a priori. Thus, standard algorithms use a part of the signal, generally the near-infrared bands, to deduce the contribution of aerosols to the signal. It is necessary to make some assumptions on the contribution of the ocean for these bands. Most of the time this contribution is determined a priori. In some situations, this approach is not relevant. Two main problems can occur: (1) The ocean contribution can not be determined a priori in the near-infrared bands; it is the case of most of the coastal waters where the content of the water is complex and not be predicted. (2) The near-infrared part of the signal is not enough to entirely deduce the aerosol contribution; it is the case of absorbing aerosol. To solve this problem, a methodology was proposed: NeuroVaria. It was based on the spectral matching principle: instead of making strong hypothesis on the oceanic contribution, a multispectral optimization is made on both oceanic and atmospheric signal. NeuroVaria alone was already validated in several cases. To improve the accuracy of the results and to process more situations, NeuroVaria was combined with a classification procedure in order to constrain the inversion. The classification was done with neuronal classifier (SOM map). The method was applied to the daily MODIS images off the Senegal coast. The resulting oceanic products were validated and a data archive of the daily MODIS data of the region is under construction. This database comprises the Chla-a concentration, the water leaving reflectance spectrum, the aerosol parameters.

Brajard, Julien; Diouf, Daouda; Crépon, Michel; Thiria, Sylvie

2013-04-01

92

Strain-compensated InP-based InGaAsInAlAs quantum cascade infrared detectors for 3-5?m atmospheric window  

NASA Astrophysics Data System (ADS)

Infrared detection within the atmospheric window between 3 to 5?m has gained great interest because of its wide range of applications, such as eye-safe free-space optical communication links and high-precision time-of-flight measurements used in 3D imaging. In this letter, we report on the characteristics of two InP-based strain-compensated InGaAs/InAlAs quantum cascade detectors (QCDs) detecting around 4 ?m and 4.5 ?m, which are promising candidates for applications in this wavelength range. Maximal responsivity values of 11.43mA/W at 180K and 10.1 mA/W at 78K and Johnson noise limited detectivities of 2.43×1010 and 2×1010 Jones at 78K, for the 4.5 ?m and the 4 ?m device, respectively, were obtained. In addition, both devices can work up to room temperature with responsivities of 0.81 mA/W(4.5?m) and 1.64 mA/W(4?m).

Zhai, Shen-qiang; Liu, Jun-qi; Kong, Ning; Liu, Feng-qi; Li, Lu; Wang, Li-jun; Wang, Zhan-guo

2011-08-01

93

A SAR image-formation algorithm that compensates for the spatially-variant effects of antenna motion  

SciTech Connect

A synthetic aperture radar (SAR) obtains azimuth resolution by combining data from a number of points along a specified path. Uncompensated antenna motion that deviates significantly from the desired path produces spatially-variant errors in the output image. The algorithm presented in this paper corrects many of these motion-related errors. In this respect, it is similar to time-domain convolution, but it is more computationally efficient. The algorithm uses overlapped subapertures in a three-step image-formation process: coarse-resolution azimuth processing, fine-resolution range processing, and fine-resolution azimuth processing. Range migration is corrected after the first stage, based on coarse azimuth position. Prior to the final azimuth-compression step, data coordinates, are determined to fine resolution in range and coarse resolution in azimuth. This coordinate information is combined with measured motion data to generate a phase correction that removes spatially-variant errors. The algorithm is well-suited for real-time applications, particularly where large flight-path deviations must be tolerated.

Burns, B.L.; Cordaro, J.T.

1994-03-01

94

Simulation of atmospheric turbulence effects and mitigation algorithms on stand-off automatic facial recognition  

NASA Astrophysics Data System (ADS)

Stand-off base and force protection surveillance measures primarily rely on electro-optic and thermal imaging technology. Atmospheric turbulence causes blur, distortion and intensity fluctuations that can severely degrade the image quality of these systems. This work explores the effects of turbulence image degradation on the performance of automatic facial recognition software and also looks at the potential benefit of turbulence mitigation algorithms. The goal of this work is to understand the feasibility of long-range facial recognition in degraded imaging conditions. In order to create a large enough database to match against, simulated imagery of different ranges and turbulence conditions were created using a horizontal view turbulence simulator and a subset of the Facial Recognition Technology (FERET) database. The simulated turbulence degraded imagery was then processed with facial recognition software and the results are compared against those from the pristine image set. Finally, the performance of the facial recognition software with turbulence mitigated imagery is also presented.

Leonard, Kevin R.; Howe, Jonathan; Oxford, David E.

2012-10-01

95

Two-dimensional atmospheric transport and chemistry model: numerical experiments with a new advection algorithm.  

PubMed

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. We generalize the original scheme to include higher-order moments. In addition, we show 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. PMID:11538482

Shia, R L; Ha, Y L; Wen, J S; Yung, Y L

1990-05-20

96

Network compensation for missing sensors  

NASA Technical Reports Server (NTRS)

A network learning translation invariance algorithm to compute interpolation functions is presented. This algorithm with one fixed receptive field can construct a linear transformation compensating for gain changes, sensor position jitter, and sensor loss when there are enough remaining sensors to adequately sample the input images. However, when the images are undersampled and complete compensation is not possible, the algorithm need to be modified. For moderate sensor losses, the algorithm works if the transformation weight adjustment is restricted to the weights to output units affected by the loss.

Ahumada, Albert J., Jr.; Mulligan, Jeffrey B.

1991-01-01

97

Fair Compensation.  

ERIC Educational Resources Information Center

A survey of 42 universities with enrollments of more than 18,000 students investigated faculty compensation practices for teaching beyond the regular academic contract, including academic schedule, length of academic term, use of faculty for overload teaching appointments, and methods of determining compensation for supplemental contracts. (MSE)

Willardson, J. D.

1998-01-01

98

Technical Note: Modification of the standard gain correction algorithm to compensate for the number of used reference flat frames in detector performance studies  

SciTech Connect

Purpose: The x-ray performance evaluation of digital x-ray detectors is based on the calculation of the modulation transfer function (MTF), the noise power spectrum (NPS), and the resultant detective quantum efficiency (DQE). The flat images used for the extraction of the NPS should not contain any fixed pattern noise (FPN) to avoid contamination from nonstochastic processes. The ''gold standard'' method used for the reduction of the FPN (i.e., the different gain between pixels) in linear x-ray detectors is based on normalization with an average reference flat-field. However, the noise in the corrected image depends on the number of flat frames used for the average flat image. The aim of this study is to modify the standard gain correction algorithm to make it independent on the used reference flat frames. Methods: Many publications suggest the use of 10-16 reference flat frames, while other studies use higher numbers (e.g., 48 frames) to reduce the propagated noise from the average flat image. This study quantifies experimentally the effect of the number of used reference flat frames on the NPS and DQE values and appropriately modifies the gain correction algorithm to compensate for this effect. Results: It is shown that using the suggested gain correction algorithm a minimum number of reference flat frames (i.e., down to one frame) can be used to eliminate the FPN from the raw flat image. This saves computer memory and time during the x-ray performance evaluation. Conclusions: The authors show that the method presented in the study (a) leads to the maximum DQE value that one would have by using the conventional method and very large number of frames and (b) has been compared to an independent gain correction method based on the subtraction of flat-field images, leading to identical DQE values. They believe this provides robust validation of the proposed method.

Konstantinidis, Anastasios C.; Olivo, Alessandro; Speller, Robert D. [Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT (United Kingdom)

2011-12-15

99

112 IEEE GEOSCIENCE AND REMOTE SENSING LETTERS, VOL. 1, NO. 2, APRIL 2004 An Improved Atmospheric Correction Algorithm for  

E-print Network

of land surface variables from hyperspectral remote sensing. One challenging issue is retrieving surface112 IEEE GEOSCIENCE AND REMOTE SENSING LETTERS, VOL. 1, NO. 2, APRIL 2004 An Improved Atmospheric Correction Algorithm for Hyperspectral Remotely Sensed Imagery Shunlin Liang, Senior Member, IEEE

Liang, Shunlin

100

Analytical algorithm for modeling polarized solar radiation transfer through the atmosphere for application in processing complex lidar and radiometer measurements  

NASA Astrophysics Data System (ADS)

Inversion algorithms and program packages recently created for processing data of the ground-based radiometer spectral measurements along with lidar multi-wavelength measurements are extremely multiparametric. Therefore, it is very important to develop an efficient program module for computations of functions modeling measurements by a sun-radiometer in the inversion procedure. In this paper, we present the analytical version of such efficient algorithm and analytical code on C++ designed for performance of algorithm testing. The code computes multiple scattering of the Sun light in the atmosphere. Data output are the radiance and linear polarization parameters angular patterns at a preselected altitude. The atmosphere model with mixed aerosol and molecular scattering is given approximately as the homogeneous atmosphere model. The algorithm testing has been carried out by comparison of computed data with accurate data obtained on the base of the discrete-ordinate code. Errors of estimates of downward radiance above the Earth surface turned out to be within 10%-15%.. The analytical solution construction concept has taken from the scalar task of solar radiation transfer in the atmosphere where an approximate analytical solution was developed. Taking into account the fact that aerosol phase functions are highly forward elongated, the multi-component method of solving vector transfer equations and small-angle approximation have been used. Generalization of the scalar approach to the polarization parameters is described.

Chaikovskaya, L.; Dubovik, O.; Litvinov, P.; Grudo, J.; Lopatsin, A.; Chaikovsky, A.; Denisov, S.

2015-01-01

101

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

102

Simulation of rice plant temperatures using the UC Davis Advanced Canopy-Atmosphere-Soil Algorithm (ACASA)  

NASA Astrophysics Data System (ADS)

The thermal environment in the plant canopy affects plants’ growth processes such as flowering and ripening. High temperatures often cause grain sterility and poor filling in serial crops, and reduce their production in tropical and temperate regions. With global warming predicted, these effects have become a major concern worldwide. In this study, we observed the plant body temperature profiles for the rice canopy and simulate them using a higher-order closure micrometeorological model to understand the relationship between plant temperatures and atmospheric condition. Experiments were conducted in rice paddy during 2007-summer season under warm temperate climate in Japan. Leaf temperatures at three different height (0.3, 0.5, 0.7m) and panicle temperatures at 0.9m were measured using fine-thermocouples. The UC Davis Advanced Canopy-Atmosphere-Soil Algorithm (ACASA) was used to calculate plant body temperature profiles in the canopy. ACASA is based on the radiation transfer, higher-order closure of turbulent equations for mass and heat exchange, and detailed plant physiological parameterization for the canopy-atmosphere-soil system. Water temperature was almost constant of 21-23 C throughout the summer because of continuous irrigation. Therefore, larger difference between air temperature at 2 m and water temperature was found on daytime. Observed leaf/panicle temperature was lower near the water surface and higher on upper layer in the canopy. Difference of temperatures between 0.3 m and 0.9 m was around 3-4 C for daytime, and around 1-2 C for nighttime. Calculated result of ACASA recreated these trends of plant temperature profile sufficiently. However, the relationship between plant and air temperature in the canopy was a little different from observed, i.e. observed leaf/panicle temperature were almost the same as air temperature, in contrast the simulated air temperature was 0.5-1.5 C higher than plant temperatures for the both of daytime and night time. This could be mainly due to the overestimation of latent heat flux in the day, and longwave cooling at night, although the precise reasons are unclear. ACASA can calculate the plant temperatures from given boundary condition, so that it is expected that it will elucidate how canopy structure (mainly leaf area index) affects thermal conditions in the canopy.

Maruyama, A.; Pyles, D.; Paw U, K.

2009-12-01

103

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

104

Performance analysis of an adaptive phase-locked tiled fiber array in atmospheric turbulence conditions  

NASA Astrophysics Data System (ADS)

We investigate performance of a tiled array of adaptive photonics phase-locked elements (APPLE) or fiber collimators for (real-time) compensation of atmospheric phase aberrations. The compensation technique is based on a decoupled stochastic parallel gradient descent (D-SPGD) optimization of performance metrics. We further compare the APPLE system and the monolithic aperture adaptive optics system based on the SPGD optimization algorithm and demonstrate that the tiled fiber array is more efficient in phase aberration compensation over the large range of atmospheric turbulence strengths and under both static and dynamic turbulence conditions.

Lachinova, Svetlana L.; Vorontsov, Mikhail A.

2005-08-01

105

An algorithm for retrieval of ocean surface and atmospheric parameters from the observations of the scanning multichannel microwave radiometer (SMMR)  

NASA Technical Reports Server (NTRS)

A formalism was developed which can be used to interpret the data in terms of sea surface temperature, sea surface wind speed, and the atmospheric overburden of water vapor and liquid water. It was shown with reasonable instrumental performance assumptions, these parameters could be derived to useful accuracies. Although the algorithms were not derived for use in rain, it is shown that, at least, token rain rates can be tolerated without invalidating the retrieved geophysical parameters.

Wilheit, T. T.; Chang, A. T. C.

1979-01-01

106

Calibrating a Soil-Vegetation-Atmosphere system with a genetical algorithm  

NASA Astrophysics Data System (ADS)

Accuracy of model prediction is well known for being very sensitive to the quality of the calibration of the model. It is also known that quantifying soil hydraulic parameters in a Soil-Vegetation-Atmosphere (SVA) system is a highly non-linear parameter estimation problem, and that 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. The SVA system in this study concerns a pine stand on a heterogeneous sandy soil (podzol) in the north of Belgium (Campine region). Throughfall and other meteorological data and water contents at different soil depths have been recorded during one year at a daily time step. The water table level, which is varying between 95 and 170 cm, has been recorded with a frequency of 0.5 hours. Based on the profile description, four soil layers have been distinguished in the podzol and used for the numerical simulation with the hydrus1D model (Simunek and al., 2005). For the inversion procedure the MYGA program (Yedder, 2002), which is an elitism GA, was used. Optimization was based on the water content measurements realized at the depths of 10, 20, 40, 50, 60, 70, 90, 110, and 120 cm to estimate parameters describing the unsaturated hydraulic soil properties of the different soil layers. Comparison between the modeled and measured water contents shows a good similarity during the simulated year. Impacts of short and intensive events (rainfall) on the water content of the soil are also well reproduced. Errors on predictions are on average equal to 5%, which is considered as a good result. A. Ben Haj Yedder. Numerical optimization and optimal control : (molecular chemistry applications). PhD thesis, Ecole Nationale des Ponts et Chaussées, 2002. Šim?nek, J., M. Th. van Genuchten, and M. Šejna, The HYDRUS-1D software package for simulating the one-dimensional movement of water, heat, and multiple solutes in variably saturated media. Version 3.0, HYDRUS Software Series 1, Department of Environmental Sciences, University of California Riverside, Riverside, CA, 270 pp., 2005.

Schneider, S.; Jacques, D.; Mallants, D.

2009-04-01

107

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

108

Top-of-atmosphere radiative fluxes - Validation of ERBE scanner inversion algorithm using Nimbus-7 ERB data  

NASA Technical Reports Server (NTRS)

The ERBE algorithm is applied to the Nimbus-7 earth radiation budget (ERB) scanner data for June 1979 to analyze the performance of an inversion method in deriving top-of-atmosphere albedos and longwave radiative fluxes. The performance is assessed by comparing ERBE algorithm results with appropriate results derived using the sorting-by-angular-bins (SAB) method, the ERB MATRIX algorithm, and the 'new-cloud ERB' (NCLE) algorithm. Comparisons are made for top-of-atmosphere albedos, longwave fluxes, viewing zenith-angle dependence of derived albedos and longwave fluxes, and cloud fractional coverage. Using the SAB method as a reference, the rms accuracy of monthly average ERBE-derived results are estimated to be 0.0165 (5.6 W/sq m) for albedos (shortwave fluxes) and 3.0 W/sq m for longwave fluxes. The ERBE-derived results were found to depend systematically on the viewing zenith angle, varying from near nadir to near the limb by about 10 percent for albedos and by 6-7 percent for longwave fluxes. Analyses indicated that the ERBE angular models are the most likely source of the systematic angular dependences. Comparison of the ERBE-derived cloud fractions, based on a maximum-likelihood estimation method, with results from the NCLE showed agreement within about 10 percent.

Suttles, John T.; Wielicki, Bruce A.; Vemury, Sastri

1992-01-01

109

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

110

Monitoring of ethylene for agro-alimentary applications and compensation of humidity effects  

Microsoft Academic Search

We used SnO2 gas sensors for monitoring ethylene in the range of interest for fruit ripening. The effect of atmospheric humidity on the sensor conductance and response towards ethylene was quantitatively measured. An algorithm for humidity compensation of the sensor’s response was developed and applied to experimental data. The results of our analysis proved useful for the application of chemoresistive

A. Giberti; M. C. Carotta; V. Guidi; C. Malagù; G. Martinelli; M. Piga; B. Vendemiati

2004-01-01

111

Comparison of atmospheric correction algorithms for the Coastal Zone Color Scanner  

NASA Technical Reports Server (NTRS)

Before Nimbus-7 Costal Zone Color Scanner (CZC) data can be used to distinguish between coastal water types, methods must be developed for the removal of spatial variations in aerosol path radiance. These can dominate radiance measurements made by the satellite. An assessment is presently made of the ability of four different algorithms to quantitatively remove haze effects; each was adapted for the extraction of the required scene-dependent parameters during an initial pass through the data set The CZCS correction algorithms considered are (1) the Gordon (1981, 1983) algorithm; (2) the Smith and Wilson (1981) iterative algorityhm; (3) the pseudooptical depth method; and (4) the residual component algorithm.

Tanis, F. J.; Jain, S. C.

1984-01-01

112

Middle atmosphere project: A radiative heating and cooling algorithm for a numerical model of the large scale stratospheric circulation  

NASA Technical Reports Server (NTRS)

A Curtis matrix is used to compute cooling by the 15 micron and 10 micron bands of carbon dioxide. Escape of radiation to space and exchange the lower boundary are used for the 9.6 micron band of ozone. Voigt line shape, vibrational relaxation, line overlap, and the temperature dependence of line strength distributions and transmission functions are incorporated into the Curtis matrices. The distributions of the atmospheric constituents included in the algorithm, and the method used to compute the Curtis matrices are discussed as well as cooling or heating by the 9.6 micron band of ozone. The FORTRAN programs and subroutines that were developed are described and listed.

Wehrbein, W. M.; Leovy, C. B.

1981-01-01

113

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

114

A comparative analysis of retrieval algorithms for GOSAT SWIR data processing: comparison against TCCON and transport model, cross-comparison, and effects of atmospheric light scattering  

NASA Astrophysics Data System (ADS)

Retrieval of precise and accurate trace gas abundances from radiance spectra of reflected sunlight from space requires accurately calculating the atmospheric light path. This report focuses on the effects of atmospheric light scattering on spectroscopic space-based observations of carbon dioxide (CO2). We summarize the results from six algorithms (ACOS B2.9, NIES 02.xx, NIES PPDF-D, NIES PPDF-S, RemoTeC, and UoL FP: 3G), which retrieve column-averaged dry air mole fractions of CO2 (XCO2) from spectra obtained by the Greenhouse Gases Observing SATellite (GOSAT) TANSO-FTS from June 2009 to March 2011. First, we compare data products from each algorithm with ground-based remote sensing observations by Fourier transform spectrometers of the Total Carbon Column Observing Network (TCCON). Our GOSAT-TCCON coincidence criteria select satellite observations over land within a 5° radius of 11 TCCON sites. We have compared the GOSAT-TCCON XCO2 standard deviation, correlation and determination coefficients, global and station-to-station biases, as well as the number of coincident observations for each algorithm. Next, the impact of atmospheric light scattering on XCO2 retrievals from each data product is estimated using the photon path length probability density function (PPDF) method. Approximately 25% of GOSAT soundings processed by the various retrieval algorithms were found to be contaminated by atmospheric light scattering, primarily due to increased optical path lengths over Northern hemispheric TCCON sites from May-September of each year. These studies, and the comparison of the satellite data with a global atmospheric transport model, suggest that most of the algorithms tend to overestimate aerosol amounts, resulting in an underestimation of XCO2 over bright surfaces. We discuss the utility of GOSAT XCO2 retrievals for improving flux inversions, focusing on the global and regional bias variability of each algorithm. Insights from this report will enable further atmospheric light scattering algorithm development.

Oshchepkov, S.; Bril, A.; Yokota, T.; Yoshida, Y.; Matsunaga, T.; Morino, I.; Wunch, D.; Wennberg, P. O.; Toon, G. C.; O'Dell, C. W.; Crisp, D.; Miller, C. E.; Frankenberg, C.; Butz, A.; Guerlet, S.; Hasekamp, O. P.; Boesch, H.; Cogan, A. J.; Parker, R.; Griffith, D. W.; Macatangay, R.; Notholt, J.; Deutscher, N. M.; Sussmann, R.; Rettinger, M.; Sherlock, V.; Robinson, J.; Kyrö, E.; Maksyutov, S.; Feist, D. G.

2012-12-01

115

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

116

Motion-Compensated JPEG 2000 Compensated  

E-print Network

temporal filter with an industry standard JPEG 2000 codec. ­ Scalable wavelet/subband coding is performed1 Motion-Compensated JPEG 2000 Motion Compensated Temporal Filter Motion Compensated Temporal Filter t Colorspace ConversionColorspace Conversion ScaleScale CrCr CbCb YY RR GG BB JPEG 2000 Encoder

Woods, John W.

117

The Implementation of Regional Atmospheric Model Numerical Algorithms for CBEA-Based Clusters  

Microsoft Academic Search

\\u000a Regional atmospheric models are important tools for short-range weather predictions and future climate change assessment.\\u000a The further enhancement of spatial resolution and development of physical parameterizations in these models need the effective\\u000a implementation of the program code on multiprocessor systems. However, nowadays typical cluster systems tend to grow into\\u000a very huge machines with over petaflop performance, while individual computing node

Dmitry Mikushin; Victor Stepanenko

2009-01-01

118

A simple algorithm to estimate the effective regional atmospheric parameters for thermal-inertia mapping  

USGS Publications Warehouse

A method based solely on remote sensing data has been developed to estimate those meteorological effects which are required for thermal-inertia mapping. It assumes that the atmospheric fluxes are spatially invariant and that the solar, sky, and sensible heat fluxes can be approximated by a simple mathematical form. Coefficients are determined from least-squares method by fitting observational data to our thermal model. A comparison between field measurements and the model-derived flux shows the type of agreement which can be achieved. An analysis of the limitations of the method is also provided. ?? 1981.

Watson, K.; Hummer-Miller, S.

1981-01-01

119

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

120

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.

U.S. Department of Justice Radiation Exposure Compensation Program

121

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

122

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

123

Compensator improvement for multivariable control systems  

NASA Technical Reports Server (NTRS)

A theory and the associated numerical technique are developed for an iterative design improvement of the compensation for linear, time-invariant control systems with multiple inputs and multiple outputs. A strict constraint algorithm is used in obtaining a solution of the specified constraints of the control design. The result of the research effort is the multiple input, multiple output Compensator Improvement Program (CIP). The objective of the Compensator Improvement Program is to modify in an iterative manner the free parameters of the dynamic compensation matrix so that the system satisfies frequency domain specifications. In this exposition, the underlying principles of the multivariable CIP algorithm are presented and the practical utility of the program is illustrated with space vehicle related examples.

Mitchell, J. R.; Mcdaniel, W. L., Jr.; Gresham, L. L.

1977-01-01

124

First results using NCAR research retrieval algorithm on Upper Atmospheric Research Satellite/Cryogenic Limb Array Etalon Spectrometer blocker 3 level 1 extracted radiances  

NASA Astrophysics Data System (ADS)

Two approaches have been explored for the retrieval of atmospheric constituent and aerosol extinction profiles from radiance measurements made by a limb sounding satellite radiometer. One of the retrieval schemes can be used with different signal to noise ratios and with measurements from different spectral regions. Multiple constituents can be retrieved simultaneously. Characterization and error analysis of the retrieved products arise naturally from theoretical considerations. The algorithms have been implemented on CLAES, an infrared limb sounder on the upper atmospheric research satellite. The CLAES measurement technique requires the level 1 extracted radiance data from CLAES to be processed before they are input to the NCAR research retrieval algorithm. The algorithms are applied to blocker 3 radiance measurements and some initial results are presented.

Gopalan, Arun; Gille, John C.; Bailey, Paul L.

1996-10-01

125

Methane emissions from tropical wetlands in LPX: Algorithm development and validation using atmospheric measurements  

NASA Astrophysics Data System (ADS)

Tropical wetlands are an important and highly uncertain term in the global budget of methane. Unlike wetlands in higher latitudes, which are dominated by water logged peatlands, tropical wetlands consist primarily of inundated river floodplains responding seasonally to variations in river discharge. Despite the fact that the hydrology of these systems is obviously very different, process models used for estimating methane emissions from wetlands commonly lack a dedicated parameterization for the tropics. This study is a first attempt to develop such a parameterization for use in the global dynamical vegetation model LPX. The required floodplain extents and water depth are calculated offline using the global hydrological model PCR-GLOBWB, which includes a sophisticated river routing scheme. LPX itself has been extended with a dedicated floodplain land unit and flood tolerant PFTs. The simulated species competition and productivity have been verified using GLC2000 and MODIS, pointing to directions for further model improvement regarding vegetation dynamics and hydrology. LPX simulated methane fluxes have been compared with available in situ measurements from tropical America. Finally, estimates for the Amazon basin have been implemented in the TM5 atmospheric transport model and compared with aircraft measured vertical profiles. The first results that will be presented demonstrate that, despite the limited availability of measurements, useful constraints on the magnitude and seasonality of Amazonian methane emissions can be derived.

Houweling, S.; Ringeval, B.; Basu, A.; Van Beek, L. P.; Van Bodegom, P.; Spahni, R.; Gatti, L.; Gloor, M.; Roeckmann, T.

2013-12-01

126

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

127

Hybrid algorithm of minimum relative entropy-particle swarm optimization with adjustment parameters for gas source term identification in atmosphere  

NASA Astrophysics Data System (ADS)

In order to identify the source term of gas emission in atmosphere, an improved hybrid algorithm combined with the minimum relative entropy (MRE) and particle swarm optimization (PSO) method was presented. Not only are the estimated source parameters obtained, but also the confidence intervals at some probability levels. If only the source strength was required to be determined, the problem can be viewed as a linear inverse problem directly, which can be solved by original MRE method successfully. When both source strength and location are unknown, the common gas dispersion model should be transformed to be a linear system. Although the transformed linear model has some differences from that in original MRE method, satisfied estimation results were still obtained by adding iteratively adaptive adjustment parameters in the MRE-PSO method. The dependence of the MRE-PSO method on prior information such as lower and upper bound, prior expected values and noises were also discussed. The results showed that the confidence intervals and estimated parameters are influenced little by the prior bounds and expected values, but the errors affect the estimation results greatly. The simulation and experiment verification results showed that the MRE-PSO method is able to identify the source parameters with satisfied results. Finally, the error model was probed and then it was added in the MRE-PSO method. The addition of error model improves the performance of the identification method. Therefore, the MRE-PSO method with adjustment parameters proposed in this paper is a potential good method to resolve inverse problem in atmosphere environment.

Ma, Denglong; Wang, Simin; Zhang, Zaoxiao

2014-09-01

128

Power Factor Compensation (PFC) Power Factor Compensation  

E-print Network

Power Factor Compensation (PFC) Power Factor Compensation The power factor (PF) is defined as the ratio between the active power and the apparent power of a system. If the current and voltage are periodic with period , and [ ), then the active power is defined by ( ) ( ) (their inner product

Knobloch,Jürgen

129

Deinterlacing based on motion compensation with variable block sizes  

NASA Astrophysics Data System (ADS)

In this paper, we propose a new deinterlacing algorithm based on motion estimation and compensation with variable block size. Motion compensated methods using a fixed block size tend to produce undesirable artifacts when there exist complicated motion and high frequency components. In the proposed algorithm, the initial block size of motion estimation is determined based on the existence of global motion. Then, the block is further divided depending on block characteristics. Since motion compensated deinterlacing may not always provide satisfactory results, the proposed method also use an intrafield spatial deinterlacing. Experimental results show that the proposed method provides noticeable improvements compared to motion compensated deinterlacing with a fixed block size.

Kim, Inho; Jeong, Taeuk; Lee, Chulhee

2006-08-01

130

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.

131

Image restoration technique for motion-compensated frame averaged data collected by 3D flash ladar imaging system  

NASA Astrophysics Data System (ADS)

A new image restoration algorithm is proposed to remove the effect of atmospheric turbulence on motion-compensated frame averaged data collected by a three dimensional FLASH Laser Radar (LADAR) imaging system. The algorithm simultaneously arrives at an enhanced image as well as Fried's seeing parameter through an Expectation Maximization (EM) technique. Unlike blind deconvolution algorithms that operate only on two dimensional images, this technique accounts for both the spatial and temporal mixing that is caused by the atmosphere through which the system is imaging. Additionally, due to the over-determined nature of this problem, the point-spread function parameterized by Fried's seeing parameter can be deduced without the requirement for additional assumptions or constraints. The utility of the approach lies in its application to laser illuminated imaging where processing time is important.

Neff, Brian J.; Cain, Stephen C.

2012-10-01

132

Compensating for camera translation in video eye-movement recordings by tracking a representative landmark selected automatically by a genetic algorithm.  

PubMed

It is common in oculomotor and vestibular research to use video or still cameras to acquire data on eye movements. Unfortunately, such data are often contaminated by unwanted motion of the face relative to the camera, especially during experiments in dynamic motion environments. We develop a method for estimating the motion of a camera relative to a highly deformable surface, specifically the movement of a camera relative to the face and eyes. A small rectangular region of interest (ROI) on the face is automatically selected and tracked throughout a set of video frames as a measure of vertical camera translation. The specific goal is to present a process based on a genetic algorithm that selects a suitable ROI for tracking: one whose translation within the camera image accurately matches the actual relative motion of the camera. We find that co-correlation, a statistic describing the time series of a large group of ROIs, predicts the accuracy of the ROIs, and can be used to select the best ROI from a group. After the genetic algorithm finds the best ROIs from a group, it uses recombination to form a new generation of ROIs that inherit properties of the ROIs from the previous generation. We show that the algorithm can select an ROI that will estimate camera translation and determine the direction that the eye is looking with an average accuracy of 0.75 degrees , even with camera translations of 2.5mm at a viewing distance of 120 mm, which would cause an error of 11 degrees without correction. PMID:18835407

Karmali, Faisal; Shelhamer, Mark

2009-01-30

133

Evaluation of the Advanced-Canopy-Atmosphere-Surface Algorithm (ACASA Model) Using Eddy Covariance Technique Over Sparse Canopy  

NASA Astrophysics Data System (ADS)

Land surface models are usually used to quantify energy and mass fluxes between terrestrial ecosystems and atmosphere on micro- and regional scales. One of the most elaborate land surface models for flux modelling is the Advanced Canopy-Atmosphere-Soil Algorithm (ACASA) model, which provides micro-scale as well as regional-scale fluxes when imbedded in a meso-scale meteorological model (e.g., MM5 or WRF). The model predicts vegetation conditions and changes with time due to plant responses to environment variables. In particular, fluxes and profiles of heat, water vapor, carbon and momentum within and above canopy are estimated using third-order equations. It also estimates turbulent profiles of velocity, temperature, humidity within and above canopy, and CO2 fluxes are estimated using a combination of Ball-Berry and Farquhar equations. The ACASA model is also able to include the effects of water stress on stomata, transpiration and CO2 assimilation. ACASA model is unique because it separates canopy domain into twenty atmospheric layers (ten layers within the canopy and ten layers above the canopy), and the soil is partitioned into fifteen layers of variable thickness. The model was mainly used over dense canopies in the past, so the aim of this work was to test the ACASA model over a sparse canopy as Mediterranean maquis. Vegetation is composed by sclerophyllous species of shrubs that are always green, with leathery leaves, small height, with a moderately sparse canopy, and that are tolerant at water stress condition. Eddy Covariance (EC) technique was used to collect continuous data for more than 3 years period. Field measurements were taken in a natural maquis site located near Alghero, Sardinia, Italy and they were used to parameterize and validate the model. The input values were selected by running the model several times varying the one parameter per time. A second step in the parameterization process was the simultaneously variation of some parameters. ACASA simulations were compared with measured fluxes of net radiation (Rn), sensible heat (H), latent heat (LE), soil heat (G), and CO2 fluxes at half-hourly time scale. Statistical analysis was made to evaluate model performance. Comparisons between simulated and measured values were evaluated using linear regression, the root mean squared error (RMSE), mean absolute error (RA), and mean bias error (MBE). Modeled data showed a good energy balance closure. ACASA estimates of net radiation were excellent. Sensible (H) and latent heat (LE) flux predictions exhibited only small differences between modeled and observed data. The ACASA model was able to capture the seasonal variation in CO2 flux. Net Ecosystem Exchange (NEE) showed the typical summer decrease due to drought induced water stress, and the simulations predicted the lower CO2 flux. Differences between simulated and observed fluxes were significant at 0.001 probability. ACASA simulations, therefore, are considered good. So, we can say that the use of ACASA to predict energy and mass fluxes between the vegetation and atmosphere is promising, and it could greatly improve our ability to estimate fluxes over natural ecosystems at both local and regional scales.

Marras, S.; Spano, D.; Sirca, C.; Duce, P.; Snyder, R.; Pyles, R. D.; Paw U, K. T.

2008-12-01

134

Simulation of GRM drag compensation system. [Geopotential Research Mission  

NASA Technical Reports Server (NTRS)

NASA's Geopotential Research Mission (GRM) was proposed in 1986 for globally determining the earth's gravitational and magnetic fields with high precision via full earth coverage polar-orbit satellites. In the GRM system, at least one of the two satellites was required to be stationed in a low-altitude, 160-km orbit subject to atmospheric drag effects that could both corrupt gravity measurements and reduce the satellite's lifetime. The Disturbance Compensation System, 'DISCOS', was incorporated to select a drag-free orbit during the active portion of GRM satellite operations by firing thrusters that offset the effects of disturbances. A drag-free thruster algorithm has been created to simulate the DISCOS system; simulation results are presented.

Antreasian, Peter G.; Lundberg, John B.; Schutz, Bob E.

1991-01-01

135

Impacts of the Convective Transport Algorithm on Atmospheric Composition and Ozone-Climate Feedbacks in GEOS-CCM  

NASA Technical Reports Server (NTRS)

Convective transport is one of the dominant factors in determining the composition of the troposphere. It is the main mechanism for lofting constituents from near-surface source regions to the middle and upper troposphere, where they can subsequently be advected over large distances. Gases reaching the upper troposphere can also be injected through the tropopause and play a subsequent role in the lower stratospheric ozone balance. Convection codes in climate models remain a great source of uncertainty for both the energy balance of the general circulation and the transport of constituents. This study uses the Goddard Earth Observing System Chemistry-Climate Model (GEOS CCM) to perform a controlled experiment that isolates the impact of convective transport of constituents from the direct changes on the atmospheric energy balance. Two multi-year simulations are conducted. In the first, the thermodynamic variable, moisture, and all trace gases are transported using the multi-plume Relaxed-Arakawa-Schubert (RAS) convective parameterization. In the second simulation, RAS impacts the thermodynamic energy and moisture in this standard manner, but all other constituents are transported differently. The accumulated convective mass fluxes (including entrainment and detrainment) computed at each time step of the GCM are used with a diffusive (bulk) algorithm for the vertical transport, which above all is less efficient at transporting constituents from the lower to the upper troposphere. Initial results show the expected differences in vertical structure of trace gases such as carbon monoxide, but also show differences in lower stratospheric ozone, in a region where it can potentially impact the climate state of the model. This work will investigate in more detail the impact of convective transport changes by comparing the two simulations over many years (1996-2010), focusing on comparisons with observed constituent distributions and similarities and differences of patterns of inter-annual variability caused by the convective transport algorithm. In particular, the impact on lower stratospheric composition will be isolated and the subsequent feedbacks of ozone on the climate forcing and tropopause structure will be assessed.

Pawson, S.; Nielsen, Jon E.; Oman, L.; Douglass, A. R.; Duncan, B. N.; Zhu, Z.

2012-01-01

136

A closed-loop selective harmonic compensation for active filters  

Microsoft Academic Search

This paper proposes a control algorithm for parallel active power filters, based on current-controlled pulsewidth-modulated converters, which allows precise compensation of selected harmonic currents produced by distorting loads. The approach is based on the measurement of line currents and performs the compensation of the selected harmonics using closed-loop synchronous frame controllers. Thanks to the closed-loop operation, full compensation of the

Paolo Mattavelli

2001-01-01

137

Practical Atmospheric Correction Algorithms for a Multi-Spectral Sensor From the Visible Through the Thermal Spectral Regions  

SciTech Connect

Deriving information about the Earth's surface requires atmospheric corrections of the measured top-of-the-atmosphere radiances. One possible path is to use atmospheric radiative transfer codes to predict how the radiance leaving the ground is affected by the scattering and attenuation. In practice the atmosphere is usually not well known and thus it is necessary to use more practical methods. The authors will describe how to find dark surfaces, estimate the atmospheric optical depth, estimate path radiance and identify thick clouds using thresholds on reflectance and NDVI and columnar water vapor. The authors describe a simple method to correct a visible channel contaminated by a thin cirrus clouds.

Borel, C.C.; Villeneuve, P.V.; Clodium, W.B.; Szymenski, J.J.; Davis, A.B.

1999-04-04

138

Distrib uted interference compensation in wireless networks  

Microsoft Academic Search

Abstract We consider a distributed power control scheme for wireless ad hoc networks, in which each user announces,a price that reflects compensation,paid by other users for their interference. We present an asynchronous,distributed algorithm for updating power levels and prices. By relating this algorithm to myopic best response updates in a fictitious game, we are able to characterize convergence using supermodular

J. Huang; R. Berry; M. L. Honig

2005-01-01

139

Robust springback compensation  

NASA Astrophysics Data System (ADS)

Springback simulation and springback compensation are more and more applied in productive use of die engineering. In order to successfully compensate a tool accurate springback results are needed as well as an effective compensation approach. In this paper a methodology has been introduce in order to effectively compensate tools. First step is the full process simulation meaning that not only the drawing operation will be simulated but also all secondary operations like trimming and flanging. Second will be the verification whether the process is robust meaning that it obtains repeatable results. In order to effectively compensate a minimum clamping concept will be defined. Once these preconditions are fulfilled the tools can be compensated effectively.

Carleer, Bart; Grimm, Peter

2013-12-01

140

Motion Estimation and Compensation for Foveated Video  

Microsoft Academic Search

Utilizing the nonuniform resolution property of the human visual system, foveated video can provide high visual quality relative to non-foveated video by allocating more bits to the central foveation area. In this paper, we present a motion estimation and compensation algorithm for foveated video and measure the performance using a new measure of visual fidelity termed foveal mean absolute distortion.

Sanghoon Lee; Alan C. Bovik

1999-01-01

141

Motion Compensation in Minimally Invasive Robotic Surgery  

Microsoft Academic Search

Abstract: Minimally invasive beating heart surgery allows a very sparing operation, butincreases the requirements for the surgeon: The remaining motion of the mechanicallystabilized beating heart makes fast and safe surgery di#cult. Thegoal of an advanced robotic surgery system is to compensate for this motion.This work presents control and vision algorithms necessary for such novel roboticsurgery applications.

Tobias Johannes Ortmaier

2003-01-01

142

Results of the Compensated Earth-Moon-Earth Retroreflector Laser Link (CEMERLL) Experiment  

NASA Technical Reports Server (NTRS)

Adaptive optics techniques can be used to realize a robust low bit-error-rate link by mitigating the atmosphere-induced signal fades in optical communications links between ground-based transmitters and deep-space probes. Phase I of the Compensated Earth-Moon-Earth Retroreflector Laser Link (CEMERLL) experiment demonstrated the first propagation of an atmosphere-compensated laser beam to the lunar retroreflectors. A 1.06-micron Nd:YAG laser beam was propagated through the full aperture of the 1.5-m telescope at the Starfire Optical Range (SOR), Kirtland Air Force Base, New Mexico, to the Apollo 15 retroreflector array at Hadley Rille. Laser guide-star adaptive optics were used to compensate turbulence-induced aberrations across the transmitter's 1.5-m aperture. A 3.5-m telescope, also located at the SOR, was used as a receiver for detecting the return signals. JPL-supplied Chebyshev polynomials of the retroreflector locations were used to develop tracking algorithms for the telescopes. At times we observed in excess of 100 photons returned from a single pulse when the outgoing beam from the 1.5-m telescope was corrected by the adaptive optics system. No returns were detected when the outgoing beam was uncompensated. The experiment was conducted from March through September 1994, during the first or last quarter of the Moon.

Wilson, K. E.; Leatherman, P. R.; Cleis, R.; Spinhirne, J.; Fugate, R. Q.

1997-01-01

143

Atmospheric dispersion compensation for extremely large telescopes  

E-print Network

: Achieving diffraction limited imaging with future ground-based optical telescopes will require adaptive propagation (010.1300), Adaptive optics (010.1080). References and links 1. F. Roddier, "The effects-only adaptive optic," Opt. Lett. 22, 588-590 (1997). 3. J. D. Barchers, "Closed-loop stable control of two

Dainty, Chris

144

Horizontal density compensation in ocean general circulation models  

NASA Astrophysics Data System (ADS)

Density compensation is the condition where temperature (T) and salinity (S) gradients counteract in their effect on density. Open ocean observations with SeaSoar tows and recent glider observations in the Gulf of Mexico reported in the scientific literature suggest that horizontal gradients in the surface mixed layer tend to be strongly density compensated over a range of spatial scales while in seasonal thermocline and deeper layers T,S-fronts are only partially compensated or uncompensated. We assess the capability of ocean general circulation models (OGCM) to develop horizontal density compensation as observed in the upper ocean. The physics required to evolve the initial density compensated mixed layer toward the partially compensated conditions of the thermocline is tested. Idealistic scenarios with horizontal, partially compensated density fronts in the mixed layer are examined in submesoscale-resolved run-down simulations on Hybrid Coordinate Ocean Model (HYCOM). Simulations with no atmospheric forcing show that initial Density compensation does not change substantially experiencing only minor decrease with time simultaneously with the restratification of the mixed layer by submesoscale eddies. Submesoscale fronts tend to be more compensated than mesoscale fronts. A sensitivity analysis shows that the density compensation of submesoscale fronts is particularly sensitive to the horizontal diffusion rate. Simulations with wind forcing exhibit destruction of initial density compensation due to ageostrophic frontogenesis which is confirmed by recent glider observations in the Gulf of Mexico. The lack of the model skill to develop and maintain compensated thermohaline variability is attributed to the T, S horizontal diffusion parameterization used in HYCOM and generally in modern OGCMs: it is decoupled from vertical diffusion and T and S diffusion is horizontally identical. Our findings suggest that OGCM's skill to develop compensated thermohaline variability can be advanced by providing realistic atmospheric forcing along with improving horizontal diffusion parameterization.

Koch, Andrey O.; Helber, Robert W.; Richman, James G.; Barron, Charlie N.

2013-04-01

145

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

146

Gmti Motion Compensation  

DOEpatents

Movement of a GMTI radar during a coherent processing interval over which a set of radar pulses are processed may cause defocusing of a range-Doppler map in the video signal. This problem may be compensated by varying waveform or sampling parameters of each pulse to compensate for distortions caused by variations in viewing angles from the radar to the target.

Doerry, Armin W. (Albuquerque, NM)

2004-07-20

147

Compensation of distributed delays in integrated communication and control systems  

NASA Technical Reports Server (NTRS)

The concept, analysis, implementation, and verification of a method for compensating delays that are distributed between the sensors, controller, and actuators within a control loop are discussed. With the objective of mitigating the detrimental effects of these network induced delays, a predictor-controller algorithm was formulated and analyzed. Robustness of the delay compensation algorithm was investigated relative to parametric uncertainties in plant modeling. The delay compensator was experimentally verified on an IEEE 802.4 network testbed for velocity control of a DC servomotor.

Ray, Asok; Luck, Rogelio

1991-01-01

148

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

149

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

150

Polynomial Compensation, Inversion, And Approximation  

NASA Technical Reports Server (NTRS)

New criterion introduced for design of discrete-time compensator. Method devised for polynomial compensation, inversion, and approximation of discrete-time linear systems. Involves quadratic measure of difference between response of compensated system and desired response. Impulse response of compensated system improves as degree of polynomial increases. Compensator emphasizes matching of large initial response. Compensators used in variety of applications, including navigation systems for spacecraft, aircraft, ships, and automated manufacturing equipment.

Baram, Yoram

1990-01-01

151

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

152

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

153

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

154

Research of static var compensator control system based on DSP technology  

Microsoft Academic Search

We present the principle of the Static Var Compensator, and introduce the design of a static var compensator control system. The design techniques of DSP CPU board and signal conditioning circuit is analyzed in this paper. We describe the fast algorithm solving reactive power and PID algorithm with variable parameter avoiding integral saturation in detail. The performance of static var

Chang-yong Zheng

2010-01-01

155

GA-based evolutionary design of robust compensator for mechatronic systems  

Microsoft Academic Search

This paper presents an evolutionary algorithm for the robust motion controller design in mechatronic systems, using the genetic algorithm. The motion control system is composed of a robust 2-DOF compensator based on the coprime factorization description. Conventional controller design approaches to the optimization for the compensator free parameters essentially require complicated numerical procedures under the given control specifications. In this

Makoto Iwasaki; Kazuaki Itoh; Nobuyuki Matsui

2001-01-01

156

An innovative approach to compensator design  

NASA Technical Reports Server (NTRS)

The design is considered of a computer-aided-compensator for a control system from a frequency domain point of view. The design technique developed is based on describing the open loop frequency response by n discrete frequency points which result in n functions of the compensator coefficients. Several of these functions are chosen so that the system specifications are properly portrayed; then mathematical programming is used to improve all of these functions which have values below minimum standards. To do this, several definitions in regard to measuring the performance of a system in the frequency domain are given, e.g., relative stability, relative attenuation, proper phasing, etc. Next, theorems which govern the number of compensator coefficients necessary to make improvements in a certain number of functions are proved. After this a mathematical programming tool for aiding in the solution of the problem is developed. This tool is called the constraint improvement algorithm. Then for applying the constraint improvement algorithm generalized, gradients for the constraints are derived. Finally, the necessary theory is incorporated in a Computer program called CIP (compensator Improvement Program). The practical usefulness of CIP is demonstrated by two large system examples.

Mitchell, J. R.; Mcdaniel, W. L., Jr.

1973-01-01

157

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

158

Executable Semantics for Compensating CSP  

Microsoft Academic Search

Compensation is an error recovery mechanism for long-running transactions. Compensating CSP is a variant of the CSP process algebra with constructs for orchestration of compensations. We present a simple operational semantics for Compensating CSP and outline an encoding of this semantics in Prolog. This provides a basis for implementation and model checking of the language.

Michael J. Butler; Shamim Ripon

2005-01-01

159

Respiratory motion compensation with relevance vector machines.  

PubMed

In modern robotic radiation therapy, tumor movements due to respiration can be compensated. The accuracy of these methods can be increased by time series prediction of external optical surrogates. An algorithm based on relevance vector machines (RVM) is introduced. We evaluate RVM with linear and nonlinear basis functions on a real patient data set containing 304 motion traces and compare it with a wavelet based least mean square algorithm (wLMS), the best algorithm for this data set so far. Linear RVM outperforms wLMS significantly and increases the prediction accuracy for 80.3% of the data. We show that real time prediction is possible in case of linear RVM and discuss how the predicted variance can be used to construct promising hybrid algorithms, which further reduce the prediction error. PMID:24579130

Dürichen, Robert; Wissel, Tobias; Ernst, Floris; Schweikard, Achim

2013-01-01

160

Parallel Implementation of the PHOENIX Generalized Stellar Atmosphere Program. III. A Parallel Algorithm for Direct Opacity Sampling  

NASA Astrophysics Data System (ADS)

We describe two parallel algorithms for line opacity calculations based on a local file and on a global file approach. The performance and scalability of both approaches is discussed for different test cases and very different parallel computing systems. The results show that a global file approach is more efficient on high-performance parallel supercomputers with dedicated parallel I/O subsystem, whereas the local file approach is very useful on farms of workstations, e.g., cheap PC clusters.

Hauschildt, Peter H.; Lowenthal, David K.; Baron, E.

2001-06-01

161

Robust beam compensation for laser-based additive manufacturing  

Microsoft Academic Search

Today’s 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

162

Compensating springback in the automotive practice using MASHAL  

NASA Astrophysics Data System (ADS)

New materials are used in the automotive industry to reduce weight and to improve crash performance. These materials feature a higher ratio of yield stress to elastic modulus leading to increased springback after tool release. The resulting shape deviations and their efficient reduction is of major interest for the automotive industry nowadays. The usual strategies for springback reduction can diminish springback to a certain amount only. In order to reduce the remaining shape deviation a mathematical compensation algorithm is presented. The objective is to obtain the tool geometry such that the part springs back into the right shape after releasing the tools. In practice the process of compensation involves different tasks beginning with CAD construction of the part, planning the drawing method and tool construction, FE-simulation, deep drawing at try-out stage and measurement of the manufactured part. Thus the compensation can not be treated as an isolated task but as a process with various restrictions and requirements of today's automotive practice. For this reason a software prototype for compensation methods MASHAL — meaning program to maintain accuracy (MASsHALtigkeit) — was developed. The basic idea of compensation with MASHAL is the transfer and application of shape deviations between two different geometries on a third one. The developed algorithm allows for an effective processing of these data, an approximation of springback and shape deviations and for a smooth extrapolation onto the tool geometry. Following topics are addressed: positioning of parts, global compensation and restriction of compensation to local areas, damping of the compensation function in the blank holder domain, simulation and validation of springback and compensation of CAD-data. The complete compensation procedure is illustrated on an industrial part.

Ohnimus, S.; Petzoldt, M.; Rietman, B.; Weiher, J.

2005-08-01

163

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

164

The Compensation Question  

ERIC Educational Resources Information Center

Over the past few years, as cash-strapped states and school districts have faced tough budget decisions, spending on teacher compensation has come under the microscope. The underlying question is whether, when you take everything into account, today's teachers are fairly paid, underpaid, or overpaid. In this forum, two pairs of respected…

Richwine, Jason; Biggs, Andrew; Mishel, Lawrence; Roy, Joydeep

2012-01-01

165

Reactive Power Compensating System.  

DOEpatents

The circuit was designed for the specific application of wind-driven induction generators. It has great potential for application in any situation where a varying reactive power load is present, such as with induction motors or generators, or for transmission network compensation.

Williams, Timothy J.; El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.

1985-01-04

166

MEMS resonator temperature compensation  

Microsoft Academic Search

This paper presents the study of an electromechanical resonator temperature compensation principle. It consists in the use of a coating material presenting opposite properties over temperature compared to the silicon resonator structural material. Simulated results, using the FEM Coventor® software, show the great potential of this CMOS compatible principle for industrial perspectives.

F. Casset; C. Durand; Y. Civet; E. Ollier; J. F. Carpentier; P. Ancey; P. Robert

2010-01-01

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

Coupling between the University of California, Davis, Advanced Canopy-Atmosphere-Soil Algorithm (ACASA) and MM5: Preliminary Results for July 1998 for Western North America.  

NASA Astrophysics Data System (ADS)

The University of California, Davis, Advanced Canopy-Atmosphere-Soil Algorithm (ACASA) is coupled to the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) as a land surface scheme. Simulations for July 1998 over western North America show that this coupling, the first between a mesoscale model and a land surface model of this complexity, is successful. Comparisons among model output, National Centers for Environmental Prediction-NCAR reanalysis fields, and station data show that MM5-ACASA generally reproduces near-surface temperature in a realistic fashion, but with a stronger diurnal cycle than observations suggest. A control run using the existing Louis/European Centre for Medium-Range Weather Forecasts land surface formulation produces unrealistically low temperatures associated with high latent heating and precipitation amounts over much of the model domain. Simulations of heat and moisture fluxes using the Biosphere-Atmosphere Transfer Scheme (BATS) are generally comparable to ACASA, but near-surface air temperatures reveal excessively warm conditions. Low specific-humidity values over land in both MM5-ACASA and MM5-BATS simulations and low oceanic values in all three simulations suggest a possible dry bias in MM5. Comparison statistics between modeled near-surface climatological behavior and associated fluxes at three sites show that MM5-ACASA, out of the three simulations, agrees most with observations. Sensitivity tests show that MM5 is generally more sensitive to the choice of surface scheme than it is to soil moisture initialization. Comparisons of mean carbon dioxide fluxes reveal that ACASA can be a useful tool in examining the terrestrial carbon cycle.

Pyles, R. David; Weare, Bryan C.; Tha Paw U, Kyaw; Gustafson, William

2003-05-01

169

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 Jiménez-Muñoz 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

170

New techniques on deformed image motion estimation and compensation.  

PubMed

In this paper, new techniques for deformed image motion estimation and compensation using variable-size block-matching are proposed, which can be applied to an image sequence compression system or a moving object recognition system. The motion estimation and compensation techniques have been successfully applied in the area of image sequence coding. Many research papers on improving the performance of these techniques have been published; many directions are proposed, which can all lead to better performance than the conventional techniques. Among them, both generalized block-matching and variable-size block-matching are successfully applied in reducing the data rate of compensation error and motion information, respectively. These two algorithms have their merits, but suffer from their drawbacks. Moreover, reducing the data rate in compensation error is sometimes increasing the data rate in motion information, or vice versa. Based on these two algorithms, we propose and examine several algorithms which are effective in reducing the data rate. We then incorporate these algorithms into a system, in which they work together to overcome the disadvantages to individual and keep their merits at the same time. The proposed system can optimally balance the amount of data rate in two aspects (i.e., compensation error and motion information). Experimental results show that the proposed system outweighs the conventional techniques. Since we propose a recovery operation which tries to recover the incorrect motion vectors from the global motion, this proposed system can also be applied to the moving object recognition in image sequences. PMID:18252362

Lin, C T; Wu, G D; Hsiao, S C

1999-01-01

171

An innovative approach to compensator design  

NASA Technical Reports Server (NTRS)

The primary goal is to present for a control system a computer-aided-compensator design technique from a frequency domain point of view. The thesis for developing this technique is to describe the open loop frequency response by n discrete frequency points which result in n functions of the compensator coefficients. Several of these functions are chosen so that the system specifications are properly portrayed; then mathematical programming is used to improve all of these functions which have values below minimum standards. In order to do this several definitions in regard to measuring the performance of a system in the frequency domain are given. Next, theorems which govern the number of compensator coefficients necessary to make improvements in a certain number of functions are proved. After this a mathematical programming tool for aiding in the solution of the problem is developed. Then for applying the constraint improvement algorithm generalized gradients for the constraints are derived. Finally, the necessary theory is incorporated in a computer program called CIP (compensator improvement program).

Mitchell, J. R.

1972-01-01

172

Open-loop position tracking control of a piezoceramic flexible beam using a dynamic hysteresis compensator  

NASA Astrophysics Data System (ADS)

This paper proposes a novel hysteresis compensator to enhance control accuracy in open-loop position tracking control of a piezoceramic flexible beam. The proposed hysteresis compensator consists of two components: a rate-independent hysteresis compensator and a nonlinear filter. The compensator is formulated based on the inverse Preisach model, while the weight coefficients of the filter are identified adaptively using a recursive least square (RLS) algorithm. In this work, two dynamic hysteresis compensators (or rate-independent hysteresis compensators) are developed by adopting two different nonlinear filters: Volterra and bilinear filters. In order to demonstrate the improved control accuracy of the proposed dynamic compensators, a flexible beam associated with the piezoceramic actuator is modeled using the finite element method (FEM) and Euler-Bernoulli beam theory. The beam model is then integrated with the proposed hysteresis model to achieve accurate position tracking control at the tip of the beam. An experimental investigation on the tip position tracking control is undertaken by realizing three different hysteresis compensators: a rate-independent hysteresis compensator, a rate-dependent hysteresis compensator with a Volterra nonlinear filter and a rate-independent hysteresis compensator with a bilinear nonlinear filter. It is shown that the proposed dynamic hysteresis compensators can provide much better tracking control accuracy than conventional rate-independent hysteresis compensators.

Nguyen, Phuong-Bac; Choi, Seung-Bok

2010-12-01

173

Executive Compensation and Corporate Fraud  

Microsoft Academic Search

We examine the relation between executive compensation and corporate fraud. Executives at fraud firms have significantly larger equity-based compensation and greater financial incentives to commit fraud than do executives at industry- and size- matched control firms. Executives at fraud firms also earn significantly more total compensation by exercising significantly larger fractions of their vested options than the control executives during

Shane A. Johnson; Harley E. Ryan; Yisong S. Tian

2003-01-01

174

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

175

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

176

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

177

ICA-based compensation for IQ imbalance in OFDM optical fiber communication  

NASA Astrophysics Data System (ADS)

A method based on the independent component analysis (ICA) is proposed to compensate the in-phase and quadrature-phase the (IQ) imbalance in orthogonal frequency division multiplexing (OFDM) optical fiber communication systems. The mathematical model of IQ imbalance system has been analyzed. Then, ICA algorithm is applied in the system to combat the mirror interference introduced by IQ imbalance. This algorithm can realize the joint compensation of both transmitter and receiver IQ imbalance with the optical channel that contains noise, attenuation and chromatic dispersion. The simulation shows that the performance degradation caused by IQ imbalance can be compensated by ICA algorithm effectively.

Jiang, Shan; Hu, Guijun; Li, Zhaoxi; Mu, Liping; Zhang, Jingdong

2014-01-01

178

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

179

Motion Compensation for UAV SAR Based on Raw Radar Data  

Microsoft Academic Search

Unmanned aerial vehicle (UAV) synthetic aperture radar (SAR) is very important for battlefield awareness. For SAR systems mounted on a UAV, the motion errors can be considerably high due to atmospheric turbulence and aircraft properties, such as its small size, which makes motion compensation (MOCO) in UAV SAR more urgent than other SAR systems. In this paper, based on 3-D

Mengdao Xing; Xiuwei Jiang; Renbiao Wu; Feng Zhou; Zheng Bao

2009-01-01

180

Springback Prediction, Compensation and Correlation for Automotive Stamping  

NASA Astrophysics Data System (ADS)

To reduce weight and increase fuel efficiency and safety, more and more automotive sheet stamping parts are being made of aluminum and high strength steels. Forming of such materials encounters not just reduced formability but also dimensional quality problems. Springback prediction accuracy and compensation effectiveness have been the major challenge to die development, construction and tryout. In this paper, the factors that affect the accuracy of springback prediction are discussed, which includes the effect of material models, the selection of element size, and the contact algorithms. Springback predictions of several automotive aluminum and high strength panels are compared with measurement data. The examples show that the prediction correlates with measurement data in both springback trend and magnitude. The effect of springback on final product can be reduced or eliminated through process control and die face compensation. The process control method involves finding the root causes of springback and eliminating them through process modification. The geometrical compensation of die surface is a direct way to eliminate the springback effect. The global scaling compensation method is normally limited to parts with relatively small springback. For large springback and twisting, a new approach is discussed, which takes into account of the effect of deformation and springback history. The compensation is achieved iteratively by solving a system of non-linear equations. Production dies were cut to the compensated surface, which shows that the die compensation is an efficient way to reduce springback-induced geometry deviation.

Xu, Siguang; Zhao, Kunmin; Lanker, Terry; Zhang, Jimmy; Wang, C. T.

2005-08-01

181

Transducer modeling and compensation in high-pressure dynamic calibration  

NASA Astrophysics Data System (ADS)

When the RBF neural network is used to establish and compensate the transducer model, the numbers of cluster need to be given in advance by using Kohonen algorithm, the RLS algorithm is complicated and the computational burden is much heavier by using it to regulate the output weights. In order to overcome the weakness, a new approach is proposed. The cluster center is decided by the subtractive clustering, and LMS algorithm is used to regulate the output weights. The noise elimination with correlative threshold plus wavelet packet transformation is used to improve the SNR. The study result shows that the network structure is simple and astringency is fast, the modeling and compensation by using the new algorithm is effective to correct the nonlinear dynamic character of transducer, and noise elimination with correlative threshold plus wavelet packet transformation is superior to conventional noise elimination methods.

Gong, Chikun; Li, Yongxin

2005-12-01

182

Block-classified motion compensation scheme for digital video  

SciTech Connect

A novel scheme for block-based motion compensation is introduced in which a block is classified according to the energy that is directly related to the motion activity it represents. This classification allows more flexibility in controlling the bit rate arid the signal-to-noise ratio and results in a reduction in motion search complexity. The method introduced is not dependent on the particular type of motion search algorithm implemented and can thus be used with any method assuming that the underlying matching criteria used is minimum absolute difference. It has been shown that the method is superior to a simple motion compensation algorithm where all blocks are motion compensated regardless of the energy resulting after the displaced difference.

Zafar, S. [Argonne National Lab., IL (United States). Mathematics and Computer Science Div.; Zhang, Ya-Qin [David Sarnoff Research Center, Princeton, NJ (United States); Jabbari, B. [George Mason Univ., Fairfax, VA (United States). Dept. of Electrical and Computer Engineering

1996-03-01

183

Software compensated multichannel pressure sensing system  

NASA Technical Reports Server (NTRS)

A PC-based software system is described which can be used for data acquisition and thermal-error correction of a multichannel pressure-sensor system developed for use in a cryogenic environment. The software incorporates pressure-sensitivity and sensor-offset compensation files into thermal error-correction algorithms, and the sensors are calibrated by simulating the operating conditions. The system is found to be effective in the collecting, storing, and processing of multichannel pressure-sensor data to correct thermally induced offset and sensitivity errors.

Chapman, John J.

1990-01-01

184

Design of ground motion compensation servo system  

NASA Astrophysics Data System (ADS)

This paper designs a ground motion compensation servo system based on two-dimensional pointing mirror. The servo system is mainly composed of digital control unit, analog driving unit and driving motor. Besides, the control algorithm and strategy of driving motor would be given, and based on the control strategy, a closed-loop controller which consists of current loop, velocity loop and position loop is designed and simulated. Especially, the speed loop adopts pseudo differential feed-forward (PDFF) controller to avoid extensive overshoot. Finally, the experiment results show that the designed servo system has fast response and small overshoot.

Tan, Chan; Ding, Lei; Chai, Jinguang

2013-05-01

185

Automatic illumination and color compensation using mean shift and sigma filter  

Microsoft Academic Search

We present a novel framework for automatic illumination and color compensation algorithm using mean shift and the sigma filter (ICCMS) to restore distorted images taken under the arbitrary lighting conditions. The proposed method is effective for appropriate illumination compensation, vivid color restoration, artifacts suppression, automatic parameter estimation, and low computational cost for HW implementation. We show the efficiency of the

Heechul Han; Kwanghoon Sohn

2009-01-01

186

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

187

LC compensators based on cost minimization for nonlinear loads  

Microsoft Academic Search

This paper describes an optimization method for the evaluation of the parameters of the LC compensator for nonlinear loads taking into account cost constraints. The solution will be obtained with an optimization algorithm based on the reduced gradient technique which will locate the maximum power factors by searching along the constant-cost power factor ridges, for the point where the gradient

M. M. A. Aziz; E. E. A. El-Zahab; A. F. Zobaa

2003-01-01

188

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

189

Compensation Performance for Induction Motor Load of Voltage Dip Compensator  

NASA Astrophysics Data System (ADS)

The variable speed drives of the power electronics application are the most sensitive to the voltage dip that is caused by power system fault. Variable speed drives are composed by the converter, the voltage source inverter and induction motor. They could fall into operation failure by wrong control in the converter when degree of the voltage dip exceeds 15% and 10ms. Therefore, important loads are equipped with the voltage dip compensation. Since the load characteristic of the converter equals nearly the impedance load, the induction motors connected directly to power supply are more sensitive to the output voltage waveform of the compensator than the converter. Thus, the induction motors are used as the important load (compensated load) on the simulation. The simulations of the compensation performance to the induction motors are carried out by using simulation tool PSCAD/EMTDC. It is confirmed that the goal of the compensation performance is able to be achieved.

Nagamoto, Takamichi; Takayama, Katsumi; Kai, Takaaki

190

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

191

Effects of atmospheric light scattering on spectroscopic observations of greenhouse gases from space. Part 2: Algorithm intercomparison in the GOSAT data processing for CO2 retrievals over TCCON sites  

NASA Astrophysics Data System (ADS)

This report is the second in a series of companion papers describing the effects of atmospheric light scattering in observations of atmospheric carbon dioxide (CO2) by the Greenhouse gases Observing SATellite (GOSAT), in orbit since 23 January 2009. Here we summarize the retrievals from six previously published algorithms; retrieving column-averaged dry air mole fractions of CO2 (XCO2) during 22 months of operation of GOSAT from June 2009. First, we compare data products from each algorithm with ground-based remote sensing observations by Total Carbon Column Observing Network (TCCON). Our GOSAT-TCCON coincidence criteria select satellite observations within a 5° radius of 11 TCCON sites. We have compared the GOSAT-TCCON XCO2 regression slope, standard deviation, correlation and determination coefficients, and global and station-to-station biases. The best agreements with TCCON measurements were detected for NIES 02.xx and RemoTeC. Next, the impact of atmospheric light scattering on XCO2 retrievals was estimated for each data product using scan by scan retrievals of light path modification with the photon path length probability density function (PPDF) method. After a cloud pre-filtering test, approximately 25% of GOSAT soundings processed by NIES 02.xx, ACOS B2.9, and UoL-FP: 3G and 35% processed by RemoTeC were found to be contaminated by atmospheric light scattering. This study suggests that NIES 02.xx and ACOS B2.9 algorithms tend to overestimate aerosol amounts over bright surfaces, resulting in an underestimation of XCO2 for GOSAT observations. Cross-comparison between algorithms shows that ACOS B2.9 agrees best with NIES 02.xx and UoL-FP: 3G while RemoTeC XCO2 retrievals are in a best agreement with NIES PPDF-D.

Oshchepkov, Sergey; Bril, Andrey; Yokota, Tatsuya; Wennberg, Paul O.; Deutscher, Nicholas M.; Wunch, Debra; Toon, Geoffrey C.; Yoshida, Yukio; O'Dell, Christopher W.; Crisp, David; Miller, Charles E.; Frankenberg, Christian; Butz, André; Aben, Ilse; Guerlet, Sandrine; Hasekamp, Otto; Boesch, Hartmut; Cogan, Austin; Parker, Robert; Griffith, David; Macatangay, Ronald; Notholt, Justus; Sussmann, Ralf; Rettinger, Markus; Sherlock, Vanessa; Robinson, John; Kyrö, Esko; Heikkinen, Pauli; Feist, Dietrich G.; Morino, Isamu; Kadygrov, Nikolay; Belikov, Dmitry; Maksyutov, Shamil; Matsunaga, Tsuneo; Uchino, Osamu; Watanabe, Hiroshi

2013-02-01

192

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

193

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

194

Fixman compensating potential for general branched molecules  

PubMed Central

The technique of constraining high frequency modes of molecular motion is an effective way to increase simulation time scale and improve conformational sampling in molecular dynamics simulations. However, it has been shown that constraints on higher frequency modes such as bond lengths and bond angles stiffen the molecular model, thereby introducing systematic biases in the statistical behavior of the simulations. Fixman proposed a compensating potential to remove such biases in the thermodynamic and kinetic properties calculated from dynamics simulations. Previous implementations of the Fixman potential have been limited to only short serial chain systems. In this paper, we present a spatial operator algebra based algorithm to calculate the Fixman potential and its gradient within constrained dynamics simulations for branched topology molecules of any size. Our numerical studies on molecules of increasing complexity validate our algorithm by demonstrating recovery of the dihedral angle probability distribution function for systems that range in complexity from serial chains to protein molecules. We observe that the Fixman compensating potential recovers the free energy surface of a serial chain polymer, thus annulling the biases caused by constraining the bond lengths and bond angles. The inclusion of Fixman potential entails only a modest increase in the computational cost in these simulations. We believe that this work represents the first instance where the Fixman potential has been used for general branched systems, and establishes the viability for its use in constrained dynamics simulations of proteins and other macromolecules. PMID:24387353

Jain, Abhinandan; Kandel, Saugat; Wagner, Jeffrey; Larsen, Adrien; Vaidehi, Nagarajan

2013-01-01

195

Fixman compensating potential for general branched molecules  

SciTech Connect

The technique of constraining high frequency modes of molecular motion is an effective way to increase simulation time scale and improve conformational sampling in molecular dynamics simulations. However, it has been shown that constraints on higher frequency modes such as bond lengths and bond angles stiffen the molecular model, thereby introducing systematic biases in the statistical behavior of the simulations. Fixman proposed a compensating potential to remove such biases in the thermodynamic and kinetic properties calculated from dynamics simulations. Previous implementations of the Fixman potential have been limited to only short serial chain systems. In this paper, we present a spatial operator algebra based algorithm to calculate the Fixman potential and its gradient within constrained dynamics simulations for branched topology molecules of any size. Our numerical studies on molecules of increasing complexity validate our algorithm by demonstrating recovery of the dihedral angle probability distribution function for systems that range in complexity from serial chains to protein molecules. We observe that the Fixman compensating potential recovers the free energy surface of a serial chain polymer, thus annulling the biases caused by constraining the bond lengths and bond angles. The inclusion of Fixman potential entails only a modest increase in the computational cost in these simulations. We believe that this work represents the first instance where the Fixman potential has been used for general branched systems, and establishes the viability for its use in constrained dynamics simulations of proteins and other macromolecules.

Jain, Abhinandan, E-mail: Abhi.Jain@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)] [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Kandel, Saugat; Wagner, Jeffrey; Larsen, Adrien; Vaidehi, Nagarajan, E-mail: nvaidehi@coh.org [Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010 (United States)] [Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010 (United States)

2013-12-28

196

Fixman compensating potential for general branched molecules.  

PubMed

The technique of constraining high frequency modes of molecular motion is an effective way to increase simulation time scale and improve conformational sampling in molecular dynamics simulations. However, it has been shown that constraints on higher frequency modes such as bond lengths and bond angles stiffen the molecular model, thereby introducing systematic biases in the statistical behavior of the simulations. Fixman proposed a compensating potential to remove such biases in the thermodynamic and kinetic properties calculated from dynamics simulations. Previous implementations of the Fixman potential have been limited to only short serial chain systems. In this paper, we present a spatial operator algebra based algorithm to calculate the Fixman potential and its gradient within constrained dynamics simulations for branched topology molecules of any size. Our numerical studies on molecules of increasing complexity validate our algorithm by demonstrating recovery of the dihedral angle probability distribution function for systems that range in complexity from serial chains to protein molecules. We observe that the Fixman compensating potential recovers the free energy surface of a serial chain polymer, thus annulling the biases caused by constraining the bond lengths and bond angles. The inclusion of Fixman potential entails only a modest increase in the computational cost in these simulations. We believe that this work represents the first instance where the Fixman potential has been used for general branched systems, and establishes the viability for its use in constrained dynamics simulations of proteins and other macromolecules. PMID:24387353

Jain, Abhinandan; Kandel, Saugat; Wagner, Jeffrey; Larsen, Adrien; Vaidehi, Nagarajan

2013-12-28

197

Fixman compensating potential for general branched molecules  

NASA Astrophysics Data System (ADS)

The technique of constraining high frequency modes of molecular motion is an effective way to increase simulation time scale and improve conformational sampling in molecular dynamics simulations. However, it has been shown that constraints on higher frequency modes such as bond lengths and bond angles stiffen the molecular model, thereby introducing systematic biases in the statistical behavior of the simulations. Fixman proposed a compensating potential to remove such biases in the thermodynamic and kinetic properties calculated from dynamics simulations. Previous implementations of the Fixman potential have been limited to only short serial chain systems. In this paper, we present a spatial operator algebra based algorithm to calculate the Fixman potential and its gradient within constrained dynamics simulations for branched topology molecules of any size. Our numerical studies on molecules of increasing complexity validate our algorithm by demonstrating recovery of the dihedral angle probability distribution function for systems that range in complexity from serial chains to protein molecules. We observe that the Fixman compensating potential recovers the free energy surface of a serial chain polymer, thus annulling the biases caused by constraining the bond lengths and bond angles. The inclusion of Fixman potential entails only a modest increase in the computational cost in these simulations. We believe that this work represents the first instance where the Fixman potential has been used for general branched systems, and establishes the viability for its use in constrained dynamics simulations of proteins and other macromolecules.

Jain, Abhinandan; Kandel, Saugat; Wagner, Jeffrey; Larsen, Adrien; Vaidehi, Nagarajan

2013-12-01

198

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.

199

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

200

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

201

Compensation and gender.  

PubMed

In a single generation, there has been a revolution in the role women play in the work-force. Unfortunately, many inequities exist between a man's experience in the workforce and a woman's most notably, the wage disparity in female-dominated professions; salary inequities between men and women within professions; and inadequate compensation packages, poor retirement benefits, and a lack of job-guaranteed family leave for women in the workforce. Movement toward rectifying these inequities is encumbered by the many polarized reactions to the various difficulties women experience and the fact that these difficulties are influenced by many factors-social/cultural, economic, and political. ASHA may begin stalking out its position by increasing awareness and understanding of the issues addressed above and identifying which issues the Association can influence through education and which may be better addressed by the government. Through educating our membership and supporting productive government solutions, ASHA may hope to improve the working woman's financial status and, therefore, her choices and opportunities. PMID:8037777

1994-05-01

202

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

203

Water Vapour GNSS Based Tomography For Wet Delay Compensation In In-SAR Applications  

NASA Astrophysics Data System (ADS)

One of the most challenging exploitation of GNSS signals for meteorological applications is the retrieval of Water Vapor tridimensional distribution. The real-time (or quasi real-time) knowledge of such distributions could be very useful for several applications: from operative meteorology to atmospheric modeling, or for atmospheric compensation purposes applied for example to SAR or In-SAR observations, in order to improve land remote sensing. In the framework of the European Space Agency project METAWAVE (Mitigation of Electromagnetic Transmission errors induced by Atmospheric Water Vapor Effects), several techniques were investigated in order to find out an In-SAR data compensation strategy for the propagation delay effects due to Water Vapour. Thanks to METAWAVE, a quite dense GPS network (7 dual frequency GPS receivers) was deployed over COMO area and was used for an extensive measurement campaign. The acquired L1 and L2 carrier phase observations were processed in terms of hourly averaged Zenith Wet Delays. These vertical information were mapped along the correspondent line of sights (by up-sampling at 30 second sample times the 15 minutes GPS satellites positions obtained from IGS files) and inverted using a tomographic procedure. The used algorithm performs a first reconstruction (namely, the tomographic pre-processing) based on generalized inversion mechanisms, in order to define a low resolution first guess for the next step. This second step inverts GPS observables using a more refined algebraic tomographic reconstruction algorithm, to improve both vertical and horizontal resolution. Results of this inversion are Wet Refractivity maps distributed over an area of 16 km x 20 km (x 10 km height) around the COMO city, characterized by horizontal resolutions varying from 2 km to 4 km and vertical resolution of 500m. This contribution deals with the description of the results obtained evaluating Water Vapour path delays from such Wet Refractivity maps. Integrals of Wet Refractivity along given line-of-sights were validated considering a self-consistency approach. Sensitivity of final results to the observation geometry will be discussed and improvements related to the ingestion of low elevation observations will be analyzed. In addition remarks about the reconstruction error in function of distance from a certain reference station and of station height will be highlighted. Finally, interesting results related to the use of high-rate real slant Delays as input to the tomography will be shown. The authors are grateful to ESA for supporting this work in the framework of the project METAWAVE, to the project PIs Prof. N. Pierdicca and Prof. F. Rocca and to G. Venuti and Prof. F. Sansò (Politecnico di Milano) for the COMO GPS network data acquisition and data processing.

Notarpietro, Riccardo; Cucca, Manuela; Perona, Giovanni

2010-05-01

204

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

205

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

206

Fundamentals of compensation and benefits.  

PubMed

The authors discuss the objectives of compensation programs--including direct and indirect forms of reward--and employee motivation. Job descriptions and job evaluations are also explored. PMID:11401793

Diorio, J A; Fallon, L F

2001-01-01

207

Temperature Compensated IBAR Reference Oscillators  

Microsoft Academic Search

This work presents a two-chip automatically temperature-compensated micromechanical IBAR reference oscillator with a temperature drift of 39ppm over 100 ° C. Temperature compensation is provided by a parabolic VPcorrection scheme and provides 10X improvement over previously reported results. Tunable 6MHz, 10MHz, and 20MHz resonators were characterized with 2000– 4500ppm tuning and Q up to 119000. Motional impedances as low as

Gavin K. Ho; Krishnakumar Sundaresan; Siavash Pourkamali; Farrokh Ayazi

2006-01-01

208

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.

209

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

210

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

211

Atmospheric and adaptive optics  

NASA Astrophysics Data System (ADS)

Atmospheric optics is the study of optical effects induced by the atmosphere on light propagating from distant sources. Of particular concern to astronomers is atmospheric turbulence, which limits the performance of ground-based telescopes. The past two decades have seen remarkable growth in the capabilities and performance of adaptive optics (AO) systems. These opto-mechanical systems actively compensate for the blurring effect of the Earth's turbulent atmosphere. By sensing, and correcting, wavefront distortion introduced by atmospheric index-of-refraction variations, AO systems can produce images with resolution approaching the diffraction limit of the telescope at near-infrared wavelengths. This review highlights the physical processes and fundamental relations of atmospheric optics that are most relevant to astronomy, and discusses the techniques used to characterize atmospheric turbulence. The fundamentals of AO are then introduced and the many types of advanced AO systems that have been developed are described. The principles of each are outlined, and the performance and limitations are examined. Aspects of photometric and astrometric measurements of AO-corrected images are considered. The paper concludes with a discussion of some of the challenges related to current and future AO systems, particularly those that will equip the next generation of large, ground-based optical and infrared telescopes.

Hickson, Paul

2014-11-01

212

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

213

A new approach to decoding and compositing motion-compensated DCT-based images  

Microsoft Academic Search

A novel decoding algorithm for the MC-DCT (motion-compensation discrete-cosine-transform)-based video, which performs inverse MC before inverse DCT, is designed. This algorithm can be applied in compositing compressed video within the network, which may take multiple compressed video sources and combine them into a single compressed output stream. The proposed algorithm convers all MC-DCT compressed video into the DCT domain and

Shih-Fu Chang; David G. Messerschmitt

1993-01-01

214

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

215

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

216

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.

217

Strategic Design of Teacher Compensation  

ERIC Educational Resources Information Center

Spurred by the national focus on revitalizing the teacher evaluation and support/development process, as well as the current economic downturn, many school districts are reviewing how teachers are compensated. While a few courageous districts have completely upended current structures, most districts are undertaking changes that leave the most…

Shields, Regis

2012-01-01

218

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

219

Ongoing transients in carbonate compensation  

Microsoft Academic Search

Uptake of anthropogenic CO2 is acidifying the oceans. Over the next 2000 years, this will modify the dissolution and preservation of sedimentary carbonate. By coupling new formulas for the positions of the calcite saturation horizon, zsat, the compensation depth, zcc, and the snowline, zsnow, to a biogeochemical model of the oceanic carbonate system, we evaluate how these horizons will change

Bernard P. Boudreau; Jack J. Middelburg; Andreas F. Hofmann; Filip J. R. Meysman

2010-01-01

220

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

221

Compensated amorphous silicon solar cell  

DOEpatents

An amorphous silicon solar cell incorporates a region of intrinsic hydrogenated amorphous silicon fabricated by a glow discharge wherein said intrinsic region is compensated by P-type dopants in an amount sufficient to reduce the space charge density of said region under illumination to about zero.

Carlson, David E. (Yardley, PA)

1980-01-01

222

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.

World Information Service on Energy Uranium Project

223

Compensation in the jobless organization  

Microsoft Academic Search

The job has traditionally played a central role in the design and structure of organizations. Recently, however, the jobless organization has emerged in response to a number of economic and technological developments. As the design and structure of organizations has changed, efforts have increasingly been made to move from the traditional job-based compensation system to a person-based approach. This paper

Brian S. Klaas

2002-01-01

224

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

225

48 CFR 836.577 - Workers' compensation.  

Code of Federal Regulations, 2012 CFR

...compensation. The contracting officer shall insert the clause at 852.236-86, Workers' compensation, in solicitations and contracts for construction that are expected to exceed the micro-purchase threshold for...

2012-10-01

226

Compensating for pneumatic distortion in pressure sensing devices  

NASA Technical Reports Server (NTRS)

A technique of compensating for pneumatic distortion in pressure sensing devices was developed and verified. This 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. Most distortion occurs within the pneumatic tubing which transmits pressure impulses from the aircraft's surface to the measurement transducer. To avoid pneumatic distortion, experiment designers mount the pressure sensor at the surface of the aircraft, (called in-situ mounting). In-situ transducers cannot always fit in the available space and sometimes pneumatic tubing must be run from the aircraft's surface to the pressure transducer. A technique to measure unsteady pressure data using conventional pressure sensing technology was developed. A pneumatic distortion model is 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 for the effects of pneumatic distortion. Both postflight and real-time algorithms are developed and evaluated using simulated and flight data.

Whitmore, Stephen A.; Leondes, Cornelius T.

1990-01-01

227

An evaluation environment for respiratory motion compensation in navigated bronchoscopy  

NASA Astrophysics Data System (ADS)

For exact orientation inside the tracheobronchial tree, clinicians would greatly profit from a soft tissue navigation system for bronchoscopy. Such an image guided system which gives the ability to show the current position of a bronchoscope (an instrument to inspect the inside of the lung) or a catheter within the tracheobronchial tree, significantly improves orientation inside the complex airway structure and the depth of insertion into it. A major challenge for a bronchoscopy navigation system is respiratory motion. Recently, more and more developments of navigated bronchoscopy systems use the tracheobronchial centerline in order to develop a compensation for respiratory motion. The implementation and evaluation of the compensation algorithms are assisted by a simulation environment, that provides tracking data similar to the data that has to be processed during a bronchoscopic intervention. Thus we developed an evaluation environment which simulates a random insertion of a tracking sensor into a tracheobronchial tree, adding electromagnetic noise and distortion similar to an operating table, and harmonic respiratory motion to the tracked position. With this environment, a high number of insertion tracks can be created and used to optimize methods for minimizing the electromagnetic tracking error and compensating respiratory movement. The authors encourage other researchers to use this evaluation environment to test different correction and estimation algorithms for navigated bronchoscopy.

Wegner, Ingmar; Tetzlaff, Ralf; Biederer, Juergen; Wolf, Ivo; Meinzer, Hans-Peter

2008-03-01

228

Incentives, School Organization and Teacher Compensation.  

ERIC Educational Resources Information Center

In order for teacher compensation to serve as an incentive that reinforces broader organizational goals, the norms of the compensation structure must be aligned with the norms of the school organization. The first section of this paper presents a brief overview of changes in teacher compensation from 1820 to 1950. It describes how such changes…

Odden, Allan

229

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

230

Jovian atmospheres  

SciTech Connect

A conference on the atmosphere of Jupiter produced papers in the areas of thermal and ortho-para hydrogen structure, clouds and chemistry, atmospheric structure, global dynamics, synoptic features and processes, atmospheric dynamics, and future spaceflight opportunities. A session on the atmospheres of Uranus and Neptune was included, and the atmosphere of Saturn was discussed in several papers.

Allison, M.; Travis, L.D.

1986-10-01

231

Using a Quadtree Algorithm To Assess Line of Sight  

NASA Technical Reports Server (NTRS)

A matched pair of computer algorithms determines whether line of sight (LOS) is obstructed by terrain. These algorithms were originally designed for use in conjunction with combat-simulation software in military training exercises, but could also be used for such commercial purposes as evaluating lines of sight for antennas or determining what can be seen from a "room with a view." The quadtree preparation algorithm operates on an array of digital elevation data and only needs to be run once for a terrain region, which can be quite large. Relatively little computation time is needed, as each elevation value is considered only one and one-third times. The LOS assessment algorithm uses that quadtree to answer LOS queries. To determine whether LOS is obstructed, a piecewise-planar (or higher-order) terrain skin is computationally draped over the digital elevation data. Adjustments are made to compensate for curvature of the Earth and for refraction of the LOS by the atmosphere. Average computing time appears to be proportional to the number of queries times the logarithm of the number of elevation data points. Accuracy is as high as is possible for the available elevation data, and symmetric results are assured. In the simulation, the LOS query program runs as a separate process, thereby making more random-access memory available for other computations.

Gonzalez, Joseph; Chamberlain, Robert; Tailor, Eric; Gutt, Gary

2006-01-01

232

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

233

29 CFR 553.221 - Compensable hours of work.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Compensable hours of work. 553.221 Section 553.221 Labor ...Agencies Tour of Duty and Compensable Hours of Work Rules § 553.221 Compensable hours of work. (a) The general rules on compensable...

2010-07-01

234

29 CFR 553.221 - Compensable hours of work.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Compensable hours of work. 553.221 Section 553.221 Labor ...Agencies Tour of Duty and Compensable Hours of Work Rules § 553.221 Compensable hours of work. (a) The general rules on compensable...

2013-07-01

235

29 CFR 553.221 - Compensable hours of work.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Compensable hours of work. 553.221 Section 553.221 Labor ...Agencies Tour of Duty and Compensable Hours of Work Rules § 553.221 Compensable hours of work. (a) The general rules on compensable...

2012-07-01

236

29 CFR 553.221 - Compensable hours of work.  

...2014-07-01 false Compensable hours of work. 553.221 Section 553.221 Labor ...Agencies Tour of Duty and Compensable Hours of Work Rules § 553.221 Compensable hours of work. (a) The general rules on compensable...

2014-07-01

237

29 CFR 553.221 - Compensable hours of work.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Compensable hours of work. 553.221 Section 553.221 Labor ...Agencies Tour of Duty and Compensable Hours of Work Rules § 553.221 Compensable hours of work. (a) The general rules on compensable...

2011-07-01

238

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

239

Modal prediction of atmospheric turbulence wavefront for open-loop liquid-crystal adaptive optics system with recursive least-squares algorithm  

NASA Astrophysics Data System (ADS)

For an open-loop liquid-crystal adaptive optics system, its performance is mainly limited by the time delay. We propose a new modal recursive least-squares (RLS) predictive algorithm to overcome this problem. The RLS algorithm has a simple architecture, low computational complexity and a high converging speed. The impact of the number of the foreword prediction frame N and the number of the predictor order M of the RLS predictor is analyzed in detail. The results show that the best foreword prediction frame N must be equal to the system loop delay frame SLDF. The appropriate predictor order M of the RLS predictor is equal to 2 or 3 when there is no measurement noise and it depends on noise ratio NR when the measurement error cannot be neglected. We present numerical simulations to show the significant improvements brought by the RLS predictor.

Liu, Chao; Hu, Lifa; Cao, Zhaoliang; Mu, Quanquan; Xuan, Li

2012-02-01

240

Compensation Techniques in Accelerator Physics  

SciTech Connect

Accelerator physics is one of the most diverse multidisciplinary fields of physics, wherein the dynamics of particle beams is studied. It takes more than the understanding of basic electromagnetic interactions to be able to predict the beam dynamics, and to be able to develop new techniques to produce, maintain, and deliver high quality beams for different applications. In this work, some basic theory regarding particle beam dynamics in accelerators will be presented. This basic theory, along with applying state of the art techniques in beam dynamics will be used in this dissertation to study and solve accelerator physics problems. Two problems involving compensation are studied in the context of the MEIC (Medium Energy Electron Ion Collider) project at Jefferson Laboratory. Several chromaticity (the energy dependence of the particle tune) compensation methods are evaluated numerically and deployed in a figure eight ring designed for the electrons in the collider. Furthermore, transverse coupling optics have been developed to compensate the coupling introduced by the spin rotators in the MEIC electron ring design.

Hisham Kamal Sayed

2011-05-31

241

Postural Compensation for Vestibular Loss  

PubMed Central

To what extent can remaining sensory information and/or sensory biofeedback compensate for loss of vestibular information in controlling postural equilibrium? The primary role of the vestibulospinal system is as a vertical reference for control of the trunk in space, with increasing importance as the surface becomes increasingly unstable. Our studies with patients with bilateral loss of vestibular function show that vision or light touch from a fingertip can substitute as a reference for earth vertical to decrease variability of trunk sway when standing on an unstable surface. However, some patients with bilateral loss compensate better than others and we find that those with more complete loss of bilateral vestibular function compensate better than those with measurable vestibulo-ocular reflexes. In contrast, patients with unilateral vestibular loss who reweight sensory dependence to rely on their remaining unilateral vestibular function show better functional performance than those who do not increase vestibular weighting on an unstable surface. Light touch of <100 grams or auditory biofeedback can be added as a vestibular vertical reference to stabilize trunk sway during stance. Postural ataxia during tandem gait in patients with unilateral vestibular loss is also significantly improved with vibrotactile biofeedback to the trunk, beyond improvements due to practice. Vestibular rehabilitation should focus on decreasing hypermetria, decreasing an over-dependence on surface somatosensory inputs, increasing use of any remaining vestibular function, substituting or adding alternative sensory feedback related to trunk sway, and practicing challenging balance tasks on unstable surfaces. PMID:20086283

Horak, Fay B.

2010-01-01

242

A fast algorithm for DCT-domain inverse motion compensation  

Microsoft Academic Search

One of the important tasks of a multiuser video network server is to composite compressed video streams from several sources into a single compressed video stream. A great deal of the computational load can be saved if this composition is performed directly in the compressed domain rather than using the brute-force approach of converting back to the uncompressed domain, compositing

Neri Merhav; Vasudev Bhaskaran

1996-01-01

243

A Fast Algorithm for DCT-Domain Inverse Motion Compensation  

Microsoft Academic Search

One of the important tasks of a multiuser video network server is to composite compressed video streams from several sources into a single compressed video stream. A great deal of the computational load can be saved if this composition is performed directly in the compressed domain rather than using the brute-force approach of con-verting back to the uncompressed domain, compositing

Neri Merhav; Vasudev Bhaskaran

1995-01-01

244

THE DEGREE OF PHASE COMPENSATION OF LASER BEAMS USING GAS JETS  

Microsoft Academic Search

When a laser beam propagates in the atmosphere, its phase can be distorted either passively, due to turbulence, or actively, due to thermal blooming. It has been demonstrated that it is possible to partially compensate for these phase errors by physically distorting the transmitting optics. The use of gas jets, with controllable density variation, that are suitably interposed in the

W. H. Christiansen; E. Wasserstrom; A. Hertzberg

1980-01-01

245

List mode reconstruction for PET with motion compensation: A simulation study  

SciTech Connect

Motion artifacts can be a significant factor that limits the image quality in high-resolution PET. Surveillance systems have been developed to track the movements of the subject during a scan. Development of reconstruction algorithms that are able to compensate for the subject motion will increase the potential of PET. In this paper we present a list mode likelihood reconstruction algorithm with the ability of motion compensation. The subject motion is explicitly modeled in the likelihood function. The detections of each detector pair are modeled as a Poisson process with time-varying rate function. The proposed method has several advantages over the existing methods. It uses all detected events and does not introduce any interpolation error. Computer simulations show that the proposed method can compensate simulated subject movements and that the reconstructed images have no visible motion artifacts.

Qi, Jinyi; Huesman, Ronald H.

2002-07-01

246

List mode reconstruction for PET with motion compensation: A simulation study  

SciTech Connect

Motion artifacts can be a significant factor that limits the image quality in high-resolution PET. Surveillance systems have been developed to track the movements of the subject during a scan. Development of reconstruction algorithms that are able to compensate for the subject motion will increase the potential of PET. In this paper we present a list mode likelihood reconstruction algorithm with the ability of motion compensation. The subject moti is explicitly modeled in the likelihood function. The detections of each detector pair are modeled as a Poisson process with time vary ingrate function. The proposed method has several advantages over the existing methods. It uses all detected events and does not introduce any interpolation error. Computer simulations show that the proposed method can compensate simulated subject movements and that the reconstructed images have no visible motion artifacts.

Qi, Jinyi; Huesman, Ronald H.

2002-07-03

247

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

248

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

249

Compensation and Working Conditions Online  

NSDL National Science Digital Library

The US Bureau of Labor Statistics (BLS) has recently begun to provide this publication, a complement to its print counterpart, via the web. The online version mirrors the articles, briefs, and tables of the print version. Some articles are available in text, and some only in Adobe Acrobat [.pdf] format. Each issue is accompanied by relevant BLS tables such as the Employment Cost Index, Major Work Stoppages, and the Occupational Compensation Survey. The present issue (Vol. 3, No. 1) contains articles on professional sports team salary caps, fatal work injuries for 1996, and scientists' earnings.

250

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

251

Vertical vibration analysis for elevator compensating sheave  

NASA Astrophysics Data System (ADS)

Most elevators applied to tall buildings include compensating ropes to satisfy the balanced rope tension between the car and the counter weight. The compensating ropes receive tension by the compensating sheave, which is installed at the bottom space of the elevator shaft. The compensating sheave is only suspended by the compensating ropes, therefore, the sheave can move vertically while the car is traveling. This paper shows the elevator dynamic model to evaluate the vertical motion of the compensating sheave. Especially, behavior in emergency cases, such as brake activation and buffer strike, was investigated to evaluate the maximum upward motion of the sheave. The simulation results were validated by experiments and the most influenced factor for the sheave vertical motion was clarified.

Watanabe, Seiji; Okawa, Takeya; Nakazawa, Daisuke; Fukui, Daiki

2013-07-01

252

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

253

A New Approach to Decoding and Compositing Motion-Compensated DCT-Based Images  

E-print Network

A New Approach to Decoding and Compositing Motion- Compensated DCT-Based Images Shih-Fu Chang the computational speedup of compositing DCT-compressed video directly in the DCT domain, compared, filtering, etc. In this paper, we propose a new decoding algorithm for MC-DCT compressed video which con

Chang, Shih-Fu

254

Subpicosecond magnetization reversal across ferrimagnetic compensation points.  

PubMed

Subpicosecond magnetization reversal is experimentally demonstrated by ultrafast heating of a ferrimagnet across its compensation points, under an applied magnetic field. While the reversal is initiated by crossing the magnetization compensation temperature, the short reversal time is related to the angular momentum compensation, where the dynamics of the system is highly accelerated owing to the divergence of the gyromagnetic ratio. These results demonstrate the feasibility of subpicosecond magnetization reversal previously believed impossible. PMID:18233247

Stanciu, C D; Tsukamoto, A; Kimel, A V; Hansteen, F; Kirilyuk, A; Itoh, A; Rasing, Th

2007-11-23

255

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

256

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

257

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

258

Compensation of static deformation and vibrations of antenna arrays  

NASA Astrophysics Data System (ADS)

The effect of vibrations and static deformations on aerospace platforms and their influence on the performance of radar, navigation or communication systems are currently studied in the scope of the NATO Research Task Groups SET-131. The deformations may be caused by different effects, e.g. aerodynamic loads, vehicle motion, moving parts such as rudders or turbines, or the impact of a collision. Depending on their strength and the function of the wireless system, they may have a significant impact on the system performance. Structural aspects of the platform such as mechanical or thermal stability, aerodynamics or outer appearance are of great importance. The present paper gives an overview of the scope of work of the group and on-going investigations on system performance analysis and compensation methods such as adaptive signal processing or electronic phase compensation for military key applications such as RADAR, Communication, Electronic Support Measures (ESM) or Command and Control (C2). In addition, the development of an antenna array demonstrator with active vibration compensation using piezo sensors and actuators and control algorithms will be shown, including simulated as well as experimental results.

Knott, Peter; Loecker, Claudius; Algermissen, Stephan; Sekora, Robert

2012-11-01

259

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

260

Electronic compensation of nonlinearly interacting signals in fiber-optical transmission lines with application of nonlinear phase filters  

NASA Astrophysics Data System (ADS)

In the article the algorithm of electronic dispersion compensation of signals transmitted by fiber-optical transmission line (FOL) are reviewed, in the presence of nonlinear effects. The algorithm is based on the use of multi-tier nonlinear phase filters (NPF). In for the solution of the problem is used of unitary characteristics of NPF. Results of modeling and the efficiency analysis of this algorithm by a comparison with the known value of the error rate.

Burdin, Vladimir A.; Grigorov, Igor V.; Tsveybelman, Evgenija L.

2014-04-01

261

The efficiency of compensation for distortions of the phase front in adaptive optical systems during measurement of its average slope  

Microsoft Academic Search

Improvement of the efficiency of the reception or transmission of laser radiation by means of compensation for large-scale phase-front distortions is considered. An algorithm of compensation for phase distortions is found, taking into account a priori information on statistical properties of the received signal and noise characteristics of the meter of the aperture-averaged phase-front slope. The efficiency of the optimal

V. E. Kirakosiants; V. A. Loginov; V. V. Slonov; A. O. Sulimov

1991-01-01

262

38 CFR 3.351 - Special monthly dependency and indemnity compensation, death compensation, pension and spouse's...  

Code of Federal Regulations, 2013 CFR

...compensation, death compensation...veteran by reason of need for aid...surviving spouse or parent by reason of being in need...6) Increased death compensation...spouse by reason of being in need...surviving spouse or parent will be...

2013-07-01

263

38 CFR 3.351 - Special monthly dependency and indemnity compensation, death compensation, pension and spouse's...  

Code of Federal Regulations, 2011 CFR

...compensation, death compensation...veteran by reason of need for aid...surviving spouse or parent by reason of being in need...6) Increased death compensation...spouse by reason of being in need...surviving spouse or parent will be...

2011-07-01

264

38 CFR 3.351 - Special monthly dependency and indemnity compensation, death compensation, pension and spouse's...  

...compensation, death compensation...veteran by reason of need for aid...surviving spouse or parent by reason of being in need...6) Increased death compensation...spouse by reason of being in need...surviving spouse or parent will be...

2014-07-01

265

38 CFR 3.351 - Special monthly dependency and indemnity compensation, death compensation, pension and spouse's...  

Code of Federal Regulations, 2012 CFR

...compensation, death compensation...veteran by reason of need for aid...surviving spouse or parent by reason of being in need...6) Increased death compensation...spouse by reason of being in need...surviving spouse or parent will be...

2012-07-01

266

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 Grundhöfer; Oliver Bimber

2008-01-01

267

44 CFR 295.21 - Allowable compensation.  

Code of Federal Regulations, 2013 CFR

...compensated. In addition the CGFAA permits FEMA to compensate Injured Parties for certain categories...receiving an award are not recoverable from FEMA. The cost to a Claimant of prosecuting...compensatory damages and is not recoverable from FEMA, except as provided in §...

2013-10-01

268

44 CFR 295.21 - Allowable compensation.  

Code of Federal Regulations, 2010 CFR

...compensated. In addition the CGFAA permits FEMA to compensate Injured Parties for certain categories...receiving an award are not recoverable from FEMA. The cost to a Claimant of prosecuting...compensatory damages and is not recoverable from FEMA, except as provided in §...

2010-10-01

269

44 CFR 295.21 - Allowable compensation.  

...compensated. In addition the CGFAA permits FEMA to compensate Injured Parties for certain categories...receiving an award are not recoverable from FEMA. The cost to a Claimant of prosecuting...compensatory damages and is not recoverable from FEMA, except as provided in §...

2014-10-01

270

44 CFR 295.21 - Allowable compensation.  

Code of Federal Regulations, 2011 CFR

...compensated. In addition the CGFAA permits FEMA to compensate Injured Parties for certain categories...receiving an award are not recoverable from FEMA. The cost to a Claimant of prosecuting...compensatory damages and is not recoverable from FEMA, except as provided in §...

2011-10-01

271

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

272

Nonlinear Dynamic Compensation For Feedback Control  

NASA Technical Reports Server (NTRS)

Nonlinear dynamic compensation scheme enhances stability of feedback control system in which feedback signal includes quantization noise. Compensator slows response of control system at low error signals to diminish effect of quantization noise but provides faster response at large error signals to speed correction of large errors.

Lin, Yu-Hwan; Lurie, Boris J.

1991-01-01

273

An Iterative Scheme for Learning Gravity Compensation  

E-print Network

An Iterative Scheme for Learning Gravity Compensation in Flexible Robot Arms A. DE LUCA, S, 00184 Roma, Italy Abstract. Mimicking the case of rigid robot arms, the set-point regulation problem for manipulators with flexible links moving under gravity can be solved by either model-based compensation or PID

De Luca, Alessandro

274

Children's Compensations for Poorly Automated Reading Skills  

ERIC Educational Resources Information Center

The compensatory-encoding model (CEM) postulates that readers whose decoding of words or verbal working memory capacities is inefficient can compensate so that literal comprehension of text is not deleteriously affected. However, the use of compensations may draw cognitive resources away from higher level reading activities such as comprehension…

Walczyk, Jeffrey J.; Marsiglia, Cheryl S.; Johns, Amanda K.; Bryan, Keli S.

2004-01-01

275

Compensation of unmodeled puma manipulator dynamics  

Microsoft Academic Search

Forces unmodeled by Lagrange-Euler dynamics restrict the trajectory tracking accuracy of dynamics based PUMA manipulator control laws. The ability of unmodeled force compensation techniques to eliminate those restrictions, enabling dynamics based PUMA controllers to accurately track a high speed trajectory, has been identified. Implementation of nonlinear velocity dependent friction compensation in the feedforward loop significantly improves controller efficacy. A combination

M. B. Leahy; G. N. Saridis

1987-01-01

276

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

277

Target Motion Compensation in MRI-guided Prostate Biopsy with Static Images  

PubMed Central

Purpose MRI-guided prostate needle biopsy requires compensation for organ motion between target planning and needle placement. Methods We propose slice-to-volume registration algorithms for tracking the prostate motion. Three orthogonal intra-operative slices are acquired in the approximate center of the prostate and registered with a high-resolution target planning volume. Both rigid and deformable scenarios were implemented. MRI-guided robotic prostate biopsy cases were analyzed retrospectively. Results Average registration errors were 2.55mm for the rigid algorithm and 2.05mm for the deformable algorithm. Conclusion Slice-based tracking appears to be promising. Deformable registration does not seem warranted. PMID:21096273

Tadayyon, Hadi; Lasso, Andras; Gill, Sean; Kaushal, Aradhana; Guion, Peter; Fichtinger, Gabor

2010-01-01

278

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

279

A New Technique for Compensating Joint Limits in a Robot Manipulator  

NASA Technical Reports Server (NTRS)

A new robust, optimal, adaptive technique for compensating rate and position limits in the joints of a six degree-of-freedom elbow manipulator is presented. In this new algorithm, the unmet demand as a result of actuator saturation is redistributed among the remaining unsaturated joints. The scheme is used to compensate for inadequate path planning, problems such as joint limiting, joint freezing, or even obstacle avoidance, where a desired position and orientation are not attainable due to an unrealizable joint command. Once a joint encounters a limit, supplemental commands are sent to other joints to best track, according to a selected criterion, the desired trajectory.

Litt, Jonathan; Hickman, Andre; Guo, Ten-Huei

1996-01-01

280

EHW Approach to Temperature Compensation of Electronics  

NASA Technical Reports Server (NTRS)

Efforts are under way to apply the concept of evolvable hardware (EHW) to compensate for variations, with temperature, in the operational characteristics of electronic circuits. To maintain the required functionality of a given circuit at a temperature above or below the nominal operating temperature for which the circuit was originally designed, a new circuit would be evolved; moreover, to obtain the required functionality over a very wide temperature range, there would be evolved a number of circuits, each of which would satisfy the performance requirements over a small part of the total temperature range. The basic concepts and some specific implementations of EHW were described in a number of previous NASA Tech Briefs articles, namely, "Reconfigurable Arrays of Transistors for Evolvable Hardware" (NPO-20078), Vol. 25, No. 2 (February 2001), page 36; Evolutionary Automated Synthesis of Electronic Circuits (NPO- 20535), Vol. 26, No. 7 (July 2002), page 37; "Designing Reconfigurable Antennas Through Hardware Evolution" (NPO-20666), Vol. 26, No. 7 (July 2002), page 38; "Morphing in Evolutionary Synthesis of Electronic Circuits" (NPO-20837), Vol. 26, No. 8 (August 2002), page 31; "Mixtrinsic Evolutionary Synthesis of Electronic Circuits" (NPO-20773) Vol. 26, No. 8 (August 2002), page 32; and "Synthesis of Fuzzy-Logic Circuits in Evolvable Hardware" (NPO-21095) Vol. 26, No. 11 (November 2002), page 38. To recapitulate from the cited prior articles: EHW is characterized as evolutionary in a quasi-genetic sense. The essence of EHW is to construct and test a sequence of populations of circuits that function as incrementally better solutions of a given design problem through the selective, repetitive connection and/or disconnection of capacitors, transistors, amplifiers, inverters, and/or other circuit building blocks. The connection and disconnection can be effected by use of field-programmable transistor arrays (FPTAs). The evolution is guided by a search-andoptimization algorithm (in particular, a genetic algorithm) that operates in the space of possible circuits to find a circuit that exhibits an acceptably close approximation of the desired functionality. The evolved circuits can be tested by mathematical modeling (that is, computational simulation) only, tested in real hardware, or tested in combinations of computational simulation and real hardware.

Stoica, Adrian

2004-01-01

281

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

282

20 CFR 404.1412 - Compensation quarters of coverage.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Compensation quarters of coverage. 404.1412 Section...Program § 404.1412 Compensation quarters of coverage. As used in this subpart, a compensation quarter of coverage is any quarter of...

2010-04-01

283

40 CFR 1066.260 - Parasitic friction compensation evaluation.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Parasitic friction compensation evaluation. 1066.260...Specifications § 1066.260 Parasitic friction compensation evaluation. (a) Overview...verify the accuracy of the dynamometer's friction compensation. (b) Scope and...

2012-07-01

284

40 CFR 1066.260 - Parasitic friction compensation evaluation.  

... 2014-07-01 false Parasitic friction compensation evaluation. 1066.260...Specifications § 1066.260 Parasitic friction compensation evaluation. (a) Overview...verify the accuracy of the dynamometer's friction compensation. (b) Scope and...

2014-07-01

285

40 CFR 1066.260 - Parasitic friction compensation evaluation.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Parasitic friction compensation evaluation. 1066.260...Specifications § 1066.260 Parasitic friction compensation evaluation. (a) Overview...verify the accuracy of the dynamometer's friction compensation. (b) Scope and...

2013-07-01

286

38 CFR 3.708 - Federal Employees' Compensation.  

Code of Federal Regulations, 2010 CFR

...Compensation, and Dependency and Indemnity Compensation Concurrent Benefits and Elections § 3.708 Federal Employees' Compensation...vested in the surviving spouse, the claimant's election controls the rights of any of the veteran's children,...

2010-07-01

287

Error Compensation for Area Digital Sun Sensor  

PubMed Central

Compared to the error factors of the Linear Array Digital Sun Sensor (DSS), those of the Area Array DSS are complicated and methods used for error compensation are not valid or simple enough. This paper presents the main error factors of the Area Array DSS and proposes an effective method to compensate them. The procedure of error compensation of Area Array DSS includes three steps. First, the geometric error of calibration is compensated; second, the coordinate map method is used to compensate the error caused by optical refraction; third, the high order polynomial-fitting method is applied to calculate the tangent of the sun angles; finally, the arc tangent method is used to calculate the sun angles. Experimental results of the product of the High Accuracy Sun Sensor indicate that the precision is better than 0.02° during the cone field of view (CFOV) of 10°, and the precision is better than 0.14° during the CFOV 10° to 64°. The proposed compensation method effectively compensates the major error factors and significantly improves the measure precision of the Area APS DSS.

Li, Wen-Yang; Zhang, Gao-Fei; You, Zheng; Xing, Fei

2012-01-01

288

Efficient Algorithms for Estimating Atmosperic Parameters for Surface Reflectance Retrieval  

Microsoft Academic Search

The objective of atmospheric correction is to retrieve the surface reflectance from remotely sensed imagery by removing the atmospheric effects. We introduce an efficient algorithm to estimate the optical characteristics of the TM imagery and to remove the atmospheric effects from it. Our algorithm introduces a set of techniques to significantly improve the quality of the retrieved images. We pay

Hassan Fallah-adl; Joseph Jájá; Shunlin Liang

1996-01-01

289

Self Organization in Compensated Semiconductors  

NASA Astrophysics Data System (ADS)

In partially compensated semiconductor (PCS) Fermi level is pinned to donor sub-band. Due to positional randomness and almost isoenergetic hoppings, donor-spanned electronic subsystem in PCS forms fluid-like highly mobile collective state. This makes PCS playground for pattern formation, self-organization, complexity emergence, electronic neural networks, and perhaps even for origins of life, bioevolution and consciousness. Through effects of impact and/or Auger ionization of donor sites, whole PCS may collapse (spinodal decomposition) into microblocks potentially capable of replication and protobiological activity (DNA analogue). Electronic screening effects may act in RNA fashion by introducing additional length scale(s) to system. Spontaneous quantum computing on charged/neutral sites becomes potential generator of informationally loaded microstructures akin to "Carl Sagan Effect" (hidden messages in Pi in his "Contact") or informational self-organization of "Library of Babel" of J.L. Borges. Even general relativity effects at Planck scale (R.Penrose) may affect the dynamics through (e.g.) isotopic variations of atomic mass and local density (A.A.Berezin, 1992). Thus, PCS can serve as toy model (experimental and computational) at interface of physics and life sciences.

Berezin, Alexander A.

2004-03-01

290

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

291

Mechanisms of X Chromosome Dosage Compensation  

PubMed Central

In many animals, males have one X and females have two X chromosomes. The difference in X chromosome dosage between the two sexes is compensated by mechanisms that regulate X chromosome transcription. Recent advances in genomic techniques have provided new insights into the molecular mechanisms of X chromosome dosage compensation. In this review, I summarize our current understanding of dosage imbalance in general, and then review the molecular mechanisms of X chromosome dosage compensation with an emphasis on the parallels and differences between the three well-studied model systems, M. musculus, D. melanogaster and C. elegans.

Ercan, Sevinç

2015-01-01

292

Image deblurring and near-real-time atmospheric seeing estimation through the employment of convergence of variance  

NASA Astrophysics Data System (ADS)

A new image reconstruction algorithm is presented that will remove the effect of atmospheric turbulence on motion compensated frame average images. The primary focus of this research was to develop a blind deconvolution technique that could be employed in a tactical military environment where both time and computational power are limited. Additionally, this technique can be employed to measure atmospheric seeing conditions. In a blind deconvolution fashion, the algorithm simultaneously computes a high resolution image and an average model for the atmospheric blur parameterized by Fried's seeing parameter. The difference in this approach is that it does not assume a prior distribution for the seeing parameter, rather it assesses the convergence of the image's variance as the stopping criteria and identification of the proper seeing parameter from a range of candidate values. Experimental results show that the convergence of variance technique allows for estimation of the seeing parameter accurate to within 0.5 cm and often even better depending on the signal to noise ratio.

Neff, Brian J.; MacManus, Quentin D.; Cain, Stephen C.; Martin, Richard K.

2013-01-01

293

Atmospheric neutrons  

NASA Technical Reports Server (NTRS)

Contributions to fast neutron measurements in the atmosphere are outlined. The results of a calculation to determine the production, distribution and final disappearance of atmospheric neutrons over the entire spectrum are presented. An attempt is made to answer questions that relate to processes such as neutron escape from the atmosphere and C-14 production. In addition, since variations of secondary neutrons can be related to variations in the primary radiation, comment on the modulation of both radiation components is made.

Korff, S. A.; Mendell, R. B.; Merker, M.; Light, E. S.; Verschell, H. J.; Sandie, W. S.

1979-01-01

294

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

295

Atmospheric dust  

NSDL National Science Digital Library

What is the purpose of dust in the atmosphere? On this activity page, part of an interactive laboratory series for grades 8-12, students read about the need for dust in the atmosphere as an agent for condensation. The addition of dust particles to the atmosphere by airplanes introduces students to the concept of cloud seeding and influencing the chance of rain in an area. Copyright 2005 Eisenhower National Clearinghouse

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

2003-01-01

296

Compensation of transmission losses for true-amplitude reverse time migration  

NASA Astrophysics Data System (ADS)

The theoretical analysis of wavefield propagators plays an important role in the development of true-amplitude migration methods. We analyze how transmission losses influence the amplitudes of reverse time migration (RTM). Based on high-frequency asymptotic theory, we analyze the change in amplitude caused by transmission losses, and prove that the transmission losses of wavefield propagation prevent RTM from yielding a true-amplitude image of the reflection coefficients. The derivations and proof provide a theoretical basis for the compensation of transmission losses in true-amplitude RTM. These theoretical derivations are then implemented in an algorithm to compensate for the transmission losses in RTM. The results from numerical experiments are consistent with the theoretical analysis. The compensation of transmission loss helps to improve the amplitude accuracy of RTM.

Du, Qizhen; Fang, Gang; Gong, Xufei; Zhang, Mingqiang

2014-07-01

297

Droop Compensation with soft Switching for High Voltage Converter Modulator (HVCM)  

SciTech Connect

High Voltage Converter Modulators (HVCM) offer significant performance advantages over conventional modulator technologies for long pulse applications. One of the key advantages of HVCM technology is the ability to compensate for capacitor bank voltage droop. Achieving droop compensation without incurring significant additional switching loss has not been possible in existing designs. This paper presents an analysis of the 'Y-point' variant of the HVCM topology using the Combined Phase and Frequency Modulation (CPFM) technique. This, combined with the addition of a 'lossless' snubber circuit, enables droop compensation while achieving soft switching over the entire pulse duration. The rise time and overshoot of the output voltage pulse is optimized using an iterative extreme seeking algorithm. The optimization reduces the rise time from 100 {micro}s to 50 {micro}s with no overshoot. This will lead to an increase in overall accelerator efficiency.

Bland, Michael [University of Nottingham; Scheinker, Alexander [Los Alamos National Laboratory; Clare, Jon [University of Nottingham; Watson, Alan [University of Nottingham; Ji, Chao [University of Nottingham; Reass, William [Los Alamos National Laboratory

2012-06-04

298

Pluto's atmosphere  

SciTech Connect

Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data. 43 references.

Elliot, J.L.; Dunham, E.W.; Bosh, A.S.; Slivan, S.M.; Young, L.A.

1989-01-01

299

Pluto's atmosphere  

NASA Technical Reports Server (NTRS)

Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data.

Elliot, J. L.; Dunham, E. W.; Bosh, A. S.; Slivan, S. M.; Young, L. A.

1989-01-01

300

A COGNITIVE COMPENSATION MECHANSIM FOR DEFORMABLE ANTENNAS  

E-print Network

bends sharply through the center up to 90 (pivoted about the ground plane) and retuning (compensation) occurs by displacing electromagnetically functionalized colloidal dispersions (EFCDs) through a capillary in the substrate (parallel to the radiating...

Long, Stephen A.

2010-07-14

301

A charge-compensated capacitor discharge generator.  

PubMed

A prototype capacitor discharge generator capable of fast termination and charge-compensated phototiming was used clinically for ten weeks. It was found to exceed all demands of ultra-fast rare-earth imaging systems. PMID:7208927

Trefler, M; Ramanathan, N; Russell, E; Gambrel, I

1981-04-01

302

Granulate of stainless steel as compensator material.  

PubMed

Compensators produced with computer controlled milling devices usually consist of a styrofoam mould, filled with an appropriate material. We investigated granulate of stainless steel as filling material. This cheap, easy to use, clean and re-usable material can be obtained with an average granule diameter of 0.3 mm, enabling an accurate and reproducible filling. No wax or other sealing material is added. The density of the granulate is approximately 4.5 g/cm3, which allows an accurate production of compensators in a sufficiently wide transmission range without the compensators becoming too thick. Transmission and surface dose measurements show that the dosimetric properties of stainless steel granulate are suitable for use as compensator material. PMID:7792403

van Santvoort, J P; Binnekamp, D; Heijmen, B J; Levendag, P C

1995-01-01

303

CEO compensation: a question of ethics  

E-print Network

reporting as the method chosen can greatly affect compensation expense, both in size and consistency, and thus manage earnings. This paper will focus on both deontological and teleological ethical models in order to show the inherent inconsistencies...

Cole, James Harrison

2013-02-22

304

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

305

7 CFR 63.107 - Compensation.  

Code of Federal Regulations, 2012 CFR

...REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG PRODUCTS INSPECTION ACT (CONTINUED) NATIONAL SHEEP INDUSTRY IMPROVEMENT CENTER General Provisions Board of Directors § 63.107 Compensation. Board members shall...

2012-01-01

306

7 CFR 63.107 - Compensation.  

...REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG PRODUCTS INSPECTION ACT (CONTINUED) NATIONAL SHEEP INDUSTRY IMPROVEMENT CENTER General Provisions Board of Directors § 63.107 Compensation. Board members shall...

2014-01-01

307

7 CFR 63.107 - Compensation.  

Code of Federal Regulations, 2011 CFR

...REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG PRODUCTS INSPECTION ACT (CONTINUED) NATIONAL SHEEP INDUSTRY IMPROVEMENT CENTER General Provisions Board of Directors § 63.107 Compensation. Board members shall...

2011-01-01

308

7 CFR 63.107 - Compensation.  

Code of Federal Regulations, 2013 CFR

...REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG PRODUCTS INSPECTION ACT (CONTINUED) NATIONAL SHEEP INDUSTRY IMPROVEMENT CENTER General Provisions Board of Directors § 63.107 Compensation. Board members shall...

2013-01-01

309

7 CFR 930.61 - Handler compensation.  

...FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE TART CHERRIES GROWN IN THE STATES OF MICHIGAN, NEW YORK, PENNSYLVANIA...930.61 Handler compensation. Each handler handling cherries from a regulated district that is subject to volume...

2014-01-01

310

Modified univibrator compensates for output timing errors  

NASA Technical Reports Server (NTRS)

One-stage, delay compensation amplifier, added to conventional univibrator circuitry time-synchronizes the trailing edge of the output pulse with the origin of the input pulse. The trailing edge is independent of the amplitude of the input pulse.

Strauss, M. G.

1967-01-01

311

Scientific investigations of atmospheric processes  

NASA Technical Reports Server (NTRS)

Research was performed in atmospheric, dynamical, and thermodynamical processes and in other disciplines necessary to accomplish the following tasks: develop procedures for combining generalized radiative transfer codes with dynamic atmospheric model codes; perform diagnostic analysis of atmospheric processes to gain a better understanding of the evolution and development of mesoscale circulation systems and their precipitation structures; and to develop algorithms and software necessary to graphically display diagnostic sets on the MSFC McIDAS and EADS to facilitate scientific study and sensor capability evaluation. Research activities during this reporting period are detailed.

1994-01-01

312

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

313

Improved charge amplifier using hybrid hysteresis compensation  

NASA Astrophysics Data System (ADS)

We present a novel charge amplifier, with a robust feedback circuit and a method for compensating piezoelectric actuator's hysteresis at low frequencies. The amplifier uses a modified feedback circuit which improves robustness to the addition of series load impedance such as in cabling. We also describe a hybrid hysteresis compensation method for enabling the charge amplifier to reduce hysteresis at low frequencies. Experimental results demonstrate the utility of the new amplifier design.

Amin-Shahidi, Darya; Trumper, David L.

2013-08-01

314

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

315

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, VOL. 10, NO. 5, AUGUST 2000 767 A Fast Algorithm for DCT-Domain Inverse Motion  

E-print Network

A Fast Algorithm for DCT-Domain Inverse Motion Compensation Based on Shared Information in a Macroblock 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

316

Atmospheric Environment ] (  

E-print Network

of neutrally stratified atmospheric boundary layers over heterogeneous terrain. Water Resources Research 42, W (Atmospheric Environment Service, Canada) [Gong, W., Taylor, P.A., Do¨ rnbrack, A., 1996. Turbulent boundary-layer boundary-layer flow over a rough two-dimensional sinusoidal hill. Three different subgrid-scale (SGS

Stoll, Rob

317

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

318

Atmospheric electricity  

Microsoft Academic Search

Owing to the somewhat explosive development of the science of atmospheric electricity during the past decade this article covers a broad field of activity. The article begins with a description and discussion of the work that has been performed to understand the electrical properties of the basic materials involved in generating processes in the atmosphere, namely ice, water, and sand

C D Stow

1969-01-01

319

Compensation for non-uniform attenuation in SPECT brain imaging  

SciTech Connect

Photon attenuation is a major limitation in performing quantitative SPECT brain imaging. A number of methods have been proposed for compensation of attenuation in regions of the body that can be modelled as a uniform attenuator. The magnitude of the errors introduced into reconstructed brain images by assuming the head to be a uniform attenuator are uncertain (the skull, sinus cavities and head holder all have different attenuation properties than brain tissue). Brain imaging is unique in that the radioisotope, for the most part, is taken up within a uniform attenuation medium (i.e., brain tissue) which is surrounded by bone (i.e., the skull) of a different density. Using this observation, Bellini`s method for attenuation compensation (which is an exact solution to the exponential Radon transform) has been modified to account for the different attenuation properties of the skull. To test this modified Bellini method, a simple mathematical phantom was designed to model the brain and a skull of varying thickness less than 7.5 mm. To model brain imaging with Tc-99m HMPAO, the attenuation coefficient of the brain tissue and skull were set to 0.15 cm{sup -1} and 0.22 cm{sup -1} respectively. A ray-driven projector which accounted for non-uniform attenuation was used to simulate projection data from 128 views. The detector response and scatter were not simulated. It was observed that reconstructions processed with uniform attenuation compensation (i.e., where it was assumed that the brain tissue and the skull had the same attenuation coefficient) provided errors of 6-20%, whereas those processed with the non-uniform Bellini algorithm were biased by only 0-5%.

Glick, S.J.; King, M.A.; Pan, T.S. [Univ. of Massachusetts Medical Center, Worcester, MA (United States)] [and others

1994-05-01

320

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

321

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

322

EUV multilayer defect compensation (MDC) by absorber pattern modification: from theory to wafer validation  

NASA Astrophysics Data System (ADS)

According to the ITRS roadmap, mask defects are among the top technical challenges to introduce extreme ultraviolet (EUV) lithography into production. Making a multilayer defect-free extreme ultraviolet (EUV) blank is not possible today, and is unlikely to happen in the next few years. This means that EUV must work with multilayer defects present on the mask. The method proposed by Luminescent is to compensate effects of multilayer defects on images by modifying the absorber patterns. The effect of a multilayer defect is to distort the images of adjacent absorber patterns. Although the defect cannot be repaired, the images may be restored to their desired targets by changing the absorber patterns. This method was first introduced in our paper at BACUS 2010, which described a simple pixel-based compensation algorithm using a fast multilayer model. The fast model made it possible to complete the compensation calculations in seconds, instead of days or weeks required for rigorous Finite Domain Time Difference (FDTD) simulations. Our SPIE 2011 paper introduced an advanced compensation algorithm using the Level Set Method for 2D absorber patterns. In this paper the method is extended to consider process window, and allow repair tool constraints, such as permitting etching but not deposition. The multilayer defect growth model is also enhanced so that the multilayer defect can be "inverted", or recovered from the top layer profile using a calibrated model.

Pang, Linyong; Hu, Peter; Satake, Masaki; Tolani, Vikram; Peng, Danping; Li, Ying; Chen, Dongxue

2011-11-01

323

Compensated amorphous silicon solar cell  

DOEpatents

An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon over said substrate and having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the electrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF.sub.3 doped intrinsic layer.

Devaud, Genevieve (629 S. Humphrey Ave., Oak Park, IL 60304)

1983-01-01

324

The research of moving object detection based on background difference compensation  

NASA Astrophysics Data System (ADS)

Moving object detection was implemented in dynamic background based on background difference compensation. Background differential can effectively segment the moving object in static background. But in moving video, the camera motion causes corresponding movement of the target and background, which makes the prospect moving object hard to separate from the background. In order to detect moving object, we can compensate the movement of the background and transfer the dynamic background to static. Moving object detection in static background image was implemented using a new weights updating method that the weights were updated during a certain period. This method based on classical Gaussian mixture model improved the efficiency of image segmentation greatly. Moving object detection in dynamic background was realized using background differential compensation. The global motion of the background was established according to the affined parameters model. The model parameters were estimated by feature points matching based on the search strategy. Invalid matching points were eliminated using the method of distance consistency. Backward mapping was used to get the motion parameters of the background. After compensation of the background with the global motion parameters, frame difference between the current frame and the background can detect moving objects effectively. Experiments were done on computer with the programming tools of VS2010 and MATLAB. Experimental results showed that the algorithm based on differential compensation was effective.

Song, Yan-bin; Ying, Jie; Lu, Lin-li

2013-08-01

325

Video codec incorporating block-based multihypothesis motion-compensated prediction  

NASA Astrophysics Data System (ADS)

Multi-hypothesis prediction extends motion compensation with one prediction signal to the linear superposition of several motion-compensated prediction signals. These motion- compensated prediction signals are referenced by motion vectors and picture reference parameters. This paper proposes a state-of-the-art video codec based on the ITU-T Recommendation H.263 that incorporates multi-hypothesis motion-compensated prediction. In contrast to B-Frames, reference pictures are always previously decoded pictures. It is demonstrated that two hypotheses are efficient for practical video compression algorithms. In addition, it is shown that multi-hypothesis motion-compensated prediction and variable block size prediction can be combined to improve the overall coding gain. The encoder utilizes rate- constrained coder control including rate-constrained multi- hypothesis motion estimation. The advanced 4-hypothesis codec improves coding efficiency up to 1.8 dB when compared to the advanced prediction codec with ten reference frames for the set of investigated test sequences.

Flierl, Markus; Wiegand, Thomas; Girod, Bernd

2000-05-01

326

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

327

STATCOM for compensation of large electric arc furnace installations  

Microsoft Academic Search

High power electronic equipment, developed for the compensation of utility power transmission systems, has been successfully applied to the problem of flicker compensation in a large industrial arc furnace. Whereas conventional flicker compensation methods, using thyristor valves in conjunction with passive components, have generally failed to reduce flicker substantially the new STATCOM-based compensator provides a dramatic reduction in flicker, as

C. Schauder

1999-01-01

328

Wind Drift Compensation in Migrating Dragonflies Pantala (Odonata: Libellulidae)  

Microsoft Academic Search

Tailwind drift compensation serves to maximize a migrant's flight distance on a given amount of energy, and crosswind drift compensation serves to hold a course true and minimize the distance flown. With full or part compensation, airspeeds are predicted to increase with greater crosswind drift. To test whether migrating dragonflies compensated for wind drift, I measured the velocity and heading

Robert B. Srygley

2003-01-01

329

Ten Questions to Ask Yourself about Compensation Surveys  

Microsoft Academic Search

Most compensation professionals use compensation surveys to some extent. Survey users should be aware that some surveys are less accurate than others, and even valid surveys may be misused or misleading. The authors provide ten questions users of compensation surveys should ask themselves about the survey before using it to make critical compensation decisions. The questions include: \\

Steve Werner; Robert Konopaske; Chris Touhey

1999-01-01

330

A distributed memory MultiLevel fast Physical Optics algorithm  

Microsoft Academic Search

The multilevel fast physical optics (MLPO) algorithm attains a computational complexity comparable to that of the fast Fourier transform (FFT) based techniques by using hierarchical domain decomposition and phase compensated interpolation approach. In this communication we present an optimized distributed memory algorithm, obtained by partitioning not only the radiating aperture but also the grid of far field directions. Such a

Christian Parrot; Daniel Millot; Christine Letrou; Amir Boag

2009-01-01

331

20 CFR 25.101 - How is compensation for disability paid?  

Code of Federal Regulations, 2012 CFR

...compensation. (20) Tongue lost: 160 weeks' compensation. (21) Ovary (one) lost: 52 weeks' compensation. (22) Uterus/cervix and vulva/vagina lost: 205 weeks' compensation. (23) Skin: 205 weeks' compensation. (24)...

2012-04-01

332

The digital implementation of control compensators: The coefficient wordlength issue  

NASA Technical Reports Server (NTRS)

There exists a number of mathematical procedures for designing discrete-time compensators. However, the digital implementation of these designs, with a microprocessor for example, has not received nearly as thorough an investigation. The finite-precision nature of the digital hardware makes it necessary to choose an algorithm (computational structure) that will perform 'well-enough' with regard to the initial objectives of the design. This paper describes a procedure for estimating the required fixed-point coefficient wordlength for any given computational structure for the implementation of a single-input single-output LOG design. The results are compared to the actual number of bits necessary to achieve a specified performance index.

Moroney, P.; Willsky, A. S.; Houpt, P. K.

1979-01-01

333

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

334

Atmospheric Mass  

NSDL National Science Digital Library

This is a lesson about the amount of atmosphere a planet is likely to have. Learners will look for the relationship between atmospheric mass and other characteristics of the planet. When the results are not completely conclusive, the students explore possible causes of discrepancies in the data. They conclude that gravity, mass and diameter all have a role in determining atmospheric mass. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson 11 in the Astro-Venture Astronomy Unit. The lessons are designed for educators to use in conjunction with the Astro-Venture multimedia modules.

335

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

336

On-line nonuniformity and temperature compensation of uncooled IRFPAs using embedded digital hardware  

NASA Astrophysics Data System (ADS)

We present a model and a signal-processing algorithm for compensating the nonuniformity (NU) noise and surrounding temperature self-heating e ects on the response of uncooled microbolometer-based infrared cameras. The model for the NU noise considers pixelwise gain and o set parameters. The representation for the self-heating dynamics of the camera is an autoregressive moving average (ARMA) model for camera's internal temperature. The algorithm performs initially a two-point calibration at a known surrounding temperature. Next, without modifying the NU parameters, we dynamically compensate variations in the camera readout using both estimates of the ARMA model and measurements of the surrounding temperature taken by a simple sensor embedded in the camera. Tested on a CEDIP Jade UC33 camera, our system compensates reference black-body images at 30 degrees Celsius, with a peak error below 1.3 and a mean error below 0.3 degrees Celsius, in scenarios where the room temperature varied up to 14 degrees Celsius. Moreover, the regularity and simplicity of the algorithm enables us to implement it on embedded digital hardware, thereby reducing its cost, size, and power consumption. We implemented the algorithm on a Xilinx XC6SLX45 FPGA using xed-point arithmetic. The circuit exhibits an arithmetic error of 0.06 degrees compared to a software double-precision implementation. It compensates 320 × 240-pixel video at up to 1,437 fps and 640 × 480-pixel video at up to 360 fps, using 1% of the logic resources of the FPGA, and less than 1 mW of dynamic power at 110 MHz. Adding Gigabit Ethernet communication, HDMI display, and a pseudocolor map on the chip uses 10% of the resources and consumes 915 mW.

Wolf, Alejandro; Redlich, Rodolfo; Figueroa, Miguel; Pezoa, Jorge E.

2013-09-01

337

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

338

Iterative control approach to compensate for the hysteresis and the vibrational dynamics effects of piezo actuators  

Microsoft Academic Search

In this article, an inversion-based iterative control (IIC) approach is used to compensate for both the hysteresis and the vibrational dynamics effects of piezo actuators during high-speed, large-range tracking. We use the Hammerstein model to capture the piezo's input-output behavior and to show the convergence of the iterative control algorithm. The IIC approach is illustrated by applying it to a

Ying Wu; Qingze Zou

2006-01-01

339

Joint source-channel coding for motion-compensated DCT-based SNR scalable video  

Microsoft Academic Search

In this paper, we develop an approach toward joint source-channel coding for motion-compensated DCT-based scal- able video coding and transmission. A framework for the optimal selection of the source and channel coding rates over all scalable layers is presented such that the overall distortion is minimized. The algorithm utilizes universal rate distortion characteristics which are obtained experimentally and show the

Lisimachos P. Kondi; Faisal Ishtiaq; Aggelos K. Katsaggelos

2002-01-01

340

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

341

A novel dual heuristic programming based optimal control of a series compensator in the electric power transmission system  

Microsoft Academic Search

In this paper, the dual heuristic programming (DHP) optimization algorithm is used for the design of a nonlinear optimal neurocontroller that replaces the proportional-integral (PI) based conventional linear controller (CONVC) in the internal control of a power electronic converter based series compensator in the electric power transmission system. The performance of the proposed DHP based neurocontroller is compared with that

Jung-Wook Park; Ronald G. Harley; Ganesh K. Venayagamoorthy

2003-01-01

342

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

343

Atmospheric Environment ] (  

E-print Network

Elsevier Ltd. All rights reserved. Keywords: 3-D CTM; Tropospheric ozone; Air quality; Ozone precursors 1 or hemispheric ozone background as an external influence on Europe's air quality in the light of the continuingAtmospheric Environment ] (

344

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.

345

Atmospheric tritium  

SciTech Connect

Research progress for the year 1979 to 1980 are reported. Concentrations of tritiated water vapor, tritium gas and tritiated hydrocarbons in the atmosphere at selected sampling points are presented. (ACR)

Oestlund, H.G.; Mason, A.S.

1980-01-01

346

Automatic time gain compensation and dynamic range control in ultrasound imaging systems  

NASA Astrophysics Data System (ADS)

For efficient and accurate diagnosis of ultrasound images, the appropriate time gain compensation (TGC) and dynamic range (DR) control of ultrasound echo signals are important. TGC is used for compensating the attenuation of ultrasound echo signals along the depth, and DR is for controlling the image contrast. In recent ultrasound systems, those two factors are automatically set by a system and/or manually adjusted by an operator to obtain the desired image quality on the screen. In this paper, we propose an algorithm to find the optimized parameter values for TGC and DR automatically. In TGC optimization, we determine the degree of attenuation compensation along the depth by reliably estimating the attenuation characteristic of ultrasound signals. For DR optimization, we define a novel cost function by properly using the characteristics of ultrasound images. Experimental results are obtained by applying the proposed algorithm to a real ultrasound (US) imaging system. The results prove that the proposed algorithm automatically sets values of TGC and DR in real-time so that the subjective quality of the enhanced ultrasound images may become good enough for efficient and accurate diagnosis.

Lee, Duhgoon; Kim, Yong Sun; Ra, Jong Beom

2006-03-01

347

Compensation performance of decision feedback equalizer in high speed optical communication system  

NASA Astrophysics Data System (ADS)

This paper discusses electronics dispersion compensation (EDC) by decision feedback equalizer (DFE) in high speed optical communication system using the LMS and the RLS algorithms, respectively. The theory of the decomposed DFE derived from basic concept of DFE in EDC is studied. Compared with the traditional DFE, the system complexity of new one has been reduced while it still keeps the high performance of DFE. Simulation results prove the validity of practicability and indicate that the decomposed DFE using RLS algorithm can more effectively eliminate intersymbol interference (ISI) after being transmitted long distance.

Lu, Li; Lei, Jianming; Bing, Linlin; Zou, Xuecheng

2008-11-01

348

Photonic crystal fiber for dispersion compensation.  

PubMed

The dispersion and mode characteristics in a dual-concentric-core photonic crystal fiber, based on pure silica, are simulated by the multipole method. The fiber exhibits very large negative dispersion due to anticrossing of two individual inner core and outer core modes. Near the wavelength of 1.55 microm, we could obtain narrowband dispersion-compensating fiber with dispersion values of -23,000 ps/km/nm, broadband dispersion-compensating fiber with dispersion values from -1000 ps/km/nm to -2500 ps/km/nm over a 200 nm range, and kappa values near 300 nm, which matched well with standard single mode fiber. It shows that even if there are some changes in the structure parameters during fabrication, these fibers can still maintain a fine dispersion-compensating property. PMID:18830310

Zhao, Xingtao; Zhou, Guiyao; Li, Shuguang; Liu, Zhaolun; Wei, Dongbin; Hou, Zhiyun; Hou, Lantian

2008-10-01

349

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

350

Isostatic compensation of equatorial highlands on Venus  

NASA Technical Reports Server (NTRS)

Spherical harmonic models for Venus' global topography and gravity incorporating Magellan data are used to test isostatic compensation models in five 30 deg x 30 deg regions representative of the main classes of equatorial highlands. The power spectral density for the harmonic models obeys a power-law scaling with spectral slope Beta approximately 2 (Brown noise) for the topography and Beta approximately 3 (Kaula's law) for the geoid, similar to what is observed for Earth. The Venus topography spectrum has lower amplitudes than Earth's which reflects the dominant lowland topography on Venus. Observed degree geoid to topography ratios (GTRs) on Venus are significantly smaller than degree GTRs for uncompensated topography, indicative of substantial compensation. Assuming a global Airy compensation, most of the topography is compensated at depths greater than 100 km, suggesting a thick lithosphere on Venus. For each region considered we obtain a regional degree of compensation C from a linear regression of Bouguer anomaly versus Bouguer gravity data. Geoid anomaly (N) versus topography variation (h) data for each sample were compared, in the least-squares sense, to theoretical correlations for Pratt, Airy, and thermal thinning isostasy models yielding regional GTR, zero-elevation crustal thickness (H), and zero elevation thermal lithosphere thickness (y(sub L(sub 0)), respectively. We find the regional compensation to be substantial (C approximately 52-80%), and the h, N data correlations in the chosen areas can be explained by isostasy models applicable on the Earth and involving variations in crustal thickness (Airy) and/or lithospheric (thermal thinning) thickness. However, a thick crust and lithosphere (y(sub L(sub 0)) approximately 300 km) must be assumed for Venus.

Kucinskas, Algis B.; Turcotte, Donald L.

1994-01-01

351

Gigabit Ethernet Asynchronous Clock Compensation FIFO  

NASA Technical Reports Server (NTRS)

Clock compensation for Gigabit Ethernet is necessary because the clock recovered from the 1.25 Gb/s serial data stream has the potential to be 200 ppm slower or faster than the system clock. The serial data is converted to 10-bit parallel data at a 125 MHz rate on a clock recovered from the serial data stream. This recovered data needs to be processed by a system clock that is also running at a nominal rate of 125 MHz, but not synchronous to the recovered clock. To cross clock domains, an asynchronous FIFO (first-in-first-out) is used, with the write pointer (wprt) in the recovered clock domain and the read pointer (rptr) in the system clock domain. Because the clocks are generated from separate sources, there is potential for FIFO overflow or underflow. Clock compensation in Gigabit Ethernet is possible by taking advantage of the protocol data stream features. There are two distinct data streams that occur in Gigabit Ethernet where identical data is transmitted for a period of time. The first is configuration, which happens during auto-negotiation. The second is idle, which occurs at the end of auto-negotiation and between every packet. The identical data in the FIFO can be repeated by decrementing the read pointer, thus compensating for a FIFO that is draining too fast. The identical data in the FIFO can also be skipped by incrementing the read pointer, which compensates for a FIFO draining too slowly. The unique and novel features of this FIFO are that it works in both the idle stream and the configuration streams. The increment or decrement of the read pointer is different in the idle and compensation streams to preserve disparity. Another unique feature is that the read pointer to write pointer difference range changes between compensation and idle to minimize FIFO latency during packet transmission.

Duhachek, Jeff

2012-01-01

352

Space-charge compensation in proton boosters  

SciTech Connect

Recently, it was proposed to use negatively charged electron beams for compensation of beam-beam effects due to protons in the Tevatron collider. We show that a similar compensation is possible in space-charge dominated low energy proton beams. The idea has a potential of several-fold increase of the FNAL Booster beam brightness. Best results will be obtained using three electron lenses around the machine circumference, using co-moving electron beam with time structure and profile approximately to the proton beam. This technique, if feasible, will be more cost effective than the straightforward alternative increasing the energy of the injection linac.

Alexey Burov; William Foster; Vladimir Shiltsev

2001-06-26

353

Efficient digital baseline wander algorithm and its architecture for fast Ethernet  

Microsoft Academic Search

The paper proposes an efficient digital baseline wander (BLW) algorithm and its hardware architecture for 100BASE-TX Ethernet. The proposed BLW compensator uses four symbols, including the present symbol, and can remove BLW at the channel having large BLW or having a killing packet. The proposed BLW compensator is purely implemented in a digital domain. To verify the performance of the

Jae H. Baek; Ju H. Hong; Myung H. Sunwoo; Kyung U. Kim

2004-01-01

354

Universal back-projection algorithm for photoacoustic computed tomography.  

PubMed

We report results of a reconstruction algorithm for three-dimensional photoacoustic computed tomography. A universal back-projection formula is presented for three types of imaging geometries: planar, spherical, and cylindrical surfaces. A solid-angle weighting factor is introduced in the back-projection formula to compensate for the variations of detection views. A method for implementing this algorithm is described. Numerical simulation is used to demonstrate the performance of the algorithm. PMID:15697763

Xu, Minghua; Wang, Lihong V

2005-01-01

355

Low Complexity Compensation of Frequency Dependent I/Q Imbalance and Carrier Frequency Offset for Direct Conversion Receivers  

NASA Astrophysics Data System (ADS)

Conventional algorithms for the joint estimation of carrier frequency offset (CFO) and I/Q imbalance no longer work when the I/Q imbalance depends on the frequency. In order to correct the imbalance across many frequencies, the compensator needed is a filter as opposed to a simple gain and phase compensator. Although, algorithms for estimating the optimal coefficients of this filter exist, their complexity is too high for hardware implementation. In this paper we present a new low complexity algorithm for joint estimation of CFO and frequency dependent I/Q imbalance. For the first part, we derive the estimation scheme using the linear least squares algorithm and examine its floating point performance compared to conventional algorithms. We show that the proposed algorithm can completely eliminate BER floor caused by CFO and I/Q imbalance at a lesser complexity compared to conventional algorithms. For the second part, we examine the hardware complexity in fixed point hardware and latency of the proposed algorithm. Based on BER performance, the circuit needs a wordlength of at least 16bits in order to properly estimate CFO and I/Q imbalance. In this configuration, the circuit is able to achieve a maximum speed of 115.9MHz in a Virtex 5 FPGA.

Lanante, Leonardo, Jr.; Kurosaki, Masayuki; Ochi, Hiroshi

356

Atmospheric Models for Aeroentry and Aeroassist  

NASA Technical Reports Server (NTRS)

Eight destinations in the Solar System have sufficient atmosphere for aeroentry, aeroassist, or aerobraking/aerocapture: Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, plus Saturn's moon Titan. Engineering-level atmospheric models for Earth, Mars, Titan, and Neptune have been developed for use in NASA s systems analysis studies of aerocapture applications. Development has begun on a similar atmospheric model for Venus. An important capability of these models is simulation of quasi-random perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithms, and for thermal systems design. Characteristics of these atmospheric models are compared, and example applications for aerocapture are presented. Recent Titan atmospheric model updates are discussed, in anticipation of applications for trajectory and atmospheric reconstruct of Huygens Probe entry at Titan. Recent and planned updates to the Mars atmospheric model, in support of future Mars aerocapture systems analysis studies, are also presented.

Justus, C. G.; Duvall, Aleta; Keller, Vernon W.

2004-01-01

357

Atmospheric instruments  

NASA Astrophysics Data System (ADS)

The National Science Foundation's (NSF) Division of Atmospheric Sciences is now accepting proposals requesting only specialized research equipment or instrumentation. The division, within the Directorate for Astronomical, Atmospheric, Earth, and Ocean Sciences (AAEO), aims to echo the theme of increased support for instrumentation of the NSF fiscal 1984 budget request to Congress.Guidelines for proposals for specialized research equipment and instrumentation are the same as those for research proposals. Each potential major user should describe the research projects for which the equipment will be used. Some institutional contribution is encouraged for the equipment proposals. For additional information on the submission of instrumentation proposals, contact the specific program director in the grant programs section (see list below) or in the new Upper Atmospheric Facilities program in NSF's Centers and Facilities section (see related news item this issue). Guidelines for proposal preparation can be found in NSF publication 81-79, Grants for Scientific and Engineering Research.

358

Automatic estimation and compensation of geometric distortions in video copies  

NASA Astrophysics Data System (ADS)

The proliferation of pirate copies of feature films on peer-to-peer networks arouses a great interest to countermeasures such as the insertion of (invisible) forensic marks in projected movies, to deter their illegal capture. The registration of pirate copies with the original content is however a prerequisite to the recovery of such embedded messages, as severe geometric distortions often occur in illegally camcorded contents. After a brief state-of-the-art in image registration, the paper details an algorithm for video registration, focusing on the compensation of geometric distortions. Control points are automatically extracted in original and copy pictures, followed by pre- and post-matching filtering steps to discard not relevant control points and erroneous matched pairs of control points respectively. This enables the accurate numerical estimation of an 8-parameter homographic distortion model, used to register the copy frames with the original reference grid. Such an image registration algorithm is inserted into a general video registration scheme. Results are presented on both natural and synthetic test material.

Chupeau, B.; Massoudi, A.; Lefèbvre, F.

2007-01-01

359

Motion compensation for fully 4D PET reconstruction using PET superset data  

NASA Astrophysics Data System (ADS)

Fully 4D PET image reconstruction is receiving increasing research interest due to its ability to significantly reduce spatiotemporal noise in dynamic PET imaging. However, thus far in the literature, the important issue of correcting for subject head motion has not been considered. Specifically, as a direct consequence of using temporally extensive basis functions, a single instance of movement propagates to impair the reconstruction of multiple time frames, even if no further movement occurs in those frames. Existing 3D motion compensation strategies have not yet been adapted to 4D reconstruction, and as such the benefits of 4D algorithms have not yet been reaped in a clinical setting where head movement undoubtedly occurs. This work addresses this need, developing a motion compensation method suitable for fully 4D reconstruction methods which exploits an optical tracking system to measure the head motion along with PET superset data to store the motion compensated data. List-mode events are histogrammed as PET superset data according to the measured motion, and a specially devised normalization scheme for motion compensated reconstruction from the superset data is required. This work proceeds to propose the corresponding time-dependent normalization modifications which are required for a major class of fully 4D image reconstruction algorithms (those which use linear combinations of temporal basis functions). Using realistically simulated as well as real high-resolution PET data from the HRRT, we demonstrate both the detrimental impact of subject head motion in fully 4D PET reconstruction and the efficacy of our proposed modifications to 4D algorithms. Benefits are shown both for the individual PET image frames as well as for parametric images of tracer uptake and volume of distribution for 18F-FDG obtained from Patlak analysis.

Verhaeghe, J.; Gravel, P.; Mio, R.; Fukasawa, R.; Rosa-Neto, P.; Soucy, J.-P.; Thompson, C. J.; Reader, A. J.

2010-07-01

360

Genetic Algorithms  

Microsoft Academic Search

Genetic algorithms (GAs) are search methods based on principles of natural selection and genetics (Fraser, 1957;Bremermann, 1958;Holland, 1975). We start with a brief introduction to simple genetic algorithms and associated terminology.

Kumara Sastry; David Goldberg; Graham Kendall

361

Compensated telescope system with programmable diffractive optic  

NASA Astrophysics Data System (ADS)

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 spatial light modulator is used as a reconfigurable diffractive optical element in a telescope system to compensate for large aberrations associated with variations in object range and field angle within the telescope's field of regard. The telescope consists of a conventional primary mirror that gimbals relative to the other components of the system and a programmable diffractive optic that compensates for more than 40 waves of aberration associated with defocus and off-axis aberrations. In this setup, aberration compensation via the programmable diffractive optic allows the object range to be varied by 160 times the depth of focus and increases the diffraction-limited field of regard by a factor of 70 while maintaining near-diffraction-limited performance.

Gruneisen, Mark T.; DeSandre, Lewis F.; Dymale, Raymond C.; Rotgé, James R.; Lubin, Donald L.

2005-02-01

362

Temperature-Compensated Clock Skew Adjustment  

PubMed Central

This work analyzes several drift compensation mechanisms in wireless sensor networks (WSN). Temperature is an environmental factor that greatly affects oscillators shipped in every WSN mote. This behavior creates the need of improving drift compensation mechanisms in synchronization protocols. Using the Flooding Time Synchronization Protocol (FTSP), this work demonstrates that crystal oscillators are affected by temperature variations. Thus, the influence of temperature provokes a low performance of FTSP in changing conditions of temperature. This article proposes an innovative correction factor that minimizes the impact of temperature in the clock skew. By means of this factor, two new mechanisms are proposed in this paper: the Adjusted Temperature (AT) and the Advanced Adjusted Temperature (A2T). These mechanisms have been combined with FTSP to produce AT-FTSP and A2T-FTSP Both have been tested in a network of TelosB motes running TinyOS. Results show that both AT-FTSP and A2T-FTSP improve the average synchronization errors compared to FTSP and other temperature-compensated protocols (Environment-Aware Clock Skew Estimation and Synchronization for WSN (EACS) and Temperature Compensated Time Synchronization (TCTS)). PMID:23966192

Castillo-Secilla, Jose María; Palomares, Jose Manuel; Olivares, Joaquín

2013-01-01

363

Space Charge Compensation in Laser Particle Accelerators  

E-print Network

Space Charge Compensation in Laser Particle Accelerators L.C. Steinhauer and W.D. Kimura STI Optronics, 2755 Northup Way, Bellevue, WA 98004-1495 Abstract. Laser particle acceleration (LPA) involves the acceleration of particle beams by electromagnetic waves with relatively short wavelength compared

Brookhaven National Laboratory

364

Thermal-difference compensation for structural members  

NASA Technical Reports Server (NTRS)

Aluminum-thermal difference link maintains constant length of strut despite environmental temperature changes. An extension spring decreases load on the compensator drive linkage when strut is in tension, when strut is in compression, a compression spring is used. Perforated titanium outer tube exposes link to external heat.

Belew, R. R.

1970-01-01

365

Large Capacity SMES for Voltage Dip Compensation  

NASA Astrophysics Data System (ADS)

Voltage dips of power grids due to thunderbolts, snow damage, and so on, cause serious damage to production lines of precision instruments, for example, semiconductors. In recent years, in order to solve this problem, uninterruptible power supply systems (UPS) are used. UPS, however, has small capacity, so a great number of UPS are needed in large factories. Therefore, we have manufactured the superconducting magnetic energy storage (SMES) system for voltage dip compensation able to protect loads with large capacity collectively. SMES has advantages such as space conservation, long lifetime and others. In field tests, cooperating with CHUBU Electric Power Co., Inc. we proved that SMES is valuable for compensating voltage dips. Since 2007, 10MVA SMES improved from field test machines has been running in a domestic liquid crystal display plant, and in 2008, it protected plant loads from a number of voltage dips. In this paper, we report the action principle and components of the improved SMES for voltage dip compensation, and examples of waveforms when 10MVA SMES compensated voltage dips.

Iwatani, Yu; Saito, Fusao; Ito, Toshinobu; Shimada, Mamoru; Ishida, Satoshi; Shimanuki, Yoshio

366

45 CFR 1607.5 - Compensation.  

Code of Federal Regulations, 2010 CFR

...SERVICES CORPORATION GOVERNING BODIES § 1607.5 Compensation...While serving on the governing body of a recipient, no attorney...by a court or administrative body or included in a settlement in...incurred by the attorney member as part of the activities undertaken...

2010-10-01

367

Laser focus compensating sensing and imaging device  

DOEpatents

A laser focus compensating sensing and imaging device permits the focus of a single focal point of different frequency laser beams emanating from the same source point. In particular it allows the focusing of laser beam originating from the same laser device but having differing intensities so that a low intensity beam will not convert to a higher frequency when passing through a conversion crystal associated with the laser generating device. The laser focus compensating sensing and imaging device uses a cassegrain system to fold the lower frequency, low intensity beam back upon itself so that it will focus at the same focal point as a high intensity beam. An angular tilt compensating lens is mounted about the secondary mirror of the cassegrain system to assist in alignment. In addition cameras or CCD's are mounted with the primary mirror to sense the focused image. A convex lens is positioned co-axial with the cassegrain system on the side of the primary mirror distal of the secondary for use in aligning a target with the laser beam. A first alternate embodiment includes a cassegrain system using a series of shutters and an internally mounted dichroic mirror. A second alternate embodiment uses two laser focus compensating sensing and imaging devices for aligning a moving tool with a work piece.

Vann, Charles S. (Fremont, CA)

1993-01-01

368

Laser focus compensating sensing and imaging device  

DOEpatents

A laser focus compensating sensing and imaging device permits the focus of a single focal point of different frequency laser beams emanating from the same source point. In particular it allows the focusing of laser beam originating from the same laser device but having differing intensities so that a low intensity beam will not convert to a higher frequency when passing through a conversion crystal associated with the laser generating device. The laser focus compensating sensing and imaging device uses a Cassegrain system to fold the lower frequency, low intensity beam back upon itself so that it will focus at the same focal point as a high intensity beam. An angular tilt compensating lens is mounted about the secondary mirror of the Cassegrain system to assist in alignment. In addition cameras or CCD's are mounted with the primary mirror to sense the focused image. A convex lens is positioned co-axial with the Cassegrain system on the side of the primary mirror distal of the secondary for use in aligning a target with the laser beam. A first alternate embodiment includes a Cassegrain system using a series of shutters and an internally mounted dichroic mirror. A second alternate embodiment uses two laser focus compensating sensing and imaging devices for aligning a moving tool with a work piece.

Vann, C.S.

1993-08-31

369

Neurocognitive Aging and the Compensation Hypothesis  

E-print Network

Neurocognitive Aging and the Compensation Hypothesis Patricia A. Reuter-Lorenz and Katherine A imaging studies of cognitive aging is evidence for age-related overactivation: greater acti- vation in older adults than in younger adults, even when performance is age-equivalent. Here we examine the hy

370

Compensators for intensity-modulated beams.  

PubMed

This study describes the importance of attenuator scatter in the construction of compensators. The attenuator used in this study was Lipowitz metal, commonly referred to as cerrobend. Linear attenuation coefficients of cerrobend were measured in air for different thickness of cerrobend sheets and different field sizes for a 6-MV photon beam. The magnitude of the dose contribution from photons scattered by the attenuator was measured. The variations of beam hardening and the scatter to primary ratio as a function of the thickness of cerrobend and varying field size were investigated. The compensators in this study were produced using a simple exponential attenuation model and the measured linear attenuation coefficients. It was found that the beam hardening effect was significant, and can lead to an error of 6.2% in the transmission, for 6 cm of cerrobend in the beam. The maximum scatter contribution to the measured fluence was 19.8% of the transmitted primary dose for a 20 x 20-cm2 field size, and 6 cm of cerrobend in the beam. For a simple wedge-step compensator; there was a maximum deviation of 6% between the measured and our predicted fluence profile. For simple compensators, this deviation can be attributed to scatter. PMID:12374378

Dimitriadis, D M; Fallone, B G

2002-01-01

371

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

372

7 CFR 301.74-5 - Compensation.  

...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...

2014-01-01

373

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

374

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

375

7 CFR 301.74-5 - Compensation.  

Code of Federal Regulations, 2013 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...

2013-01-01

376

Passive dual spin misalignment compensators. [gyrostabilized device  

NASA Technical Reports Server (NTRS)

A combination dual-spin gyroscopically stabilized device is described having a spinning rotor and a non-spinning platform. Two substantially lossless mechanical resonators, resonant at the spin frequency, are orthogonally positioned on the platform for compensation for the disturbing torque acting on the platform due to rotor misalignment.

Donohue, J. H.; Zimmerman, B. G. (inventors)

1974-01-01

377

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

378

Subreflectarrays for Reflector Surface Distortion Compensation  

Microsoft Academic Search

With the increasing interest in the applications of large deployable reflector antennas operating at high frequencies, the requirement on the reflector surface accuracy becomes more demanding. Thermal effects inevitably cause certain reflector surface distortions, thus degrading the overall antenna performance. This paper introduces a novel reflector surface distortion compensation technique using a subreflectarray and presents detailed discussions. A microstrip reflectarray

Shenheng Xu; Yahya Rahmat-Samii; William A. Imbriale

2009-01-01

379

AGENCY CONFLICTS, MANAGERIAL COMPENSATION, AND FIRM VARIANCE  

Microsoft Academic Search

This paper presents a theoretical model of the agency conflict between managers and shareholders. The problem is examined in an expected-utility-maximization scenario in which the explicit cost of the agency conflict that arises between the manager and shareholders is derived. The model determines the effect of changes in firm variance on various compensation components. Development of this model depends upon

Robert L. Lippert

380

Friction Compensation in Robotics: an Overview  

Microsoft Academic Search

Friction effects are particularly critical for industrial robots, since they can induce large positioning errors, stick-slip motions, and limit cycles. This paper offers a reasoned overview of the main friction compensation techniques that have been developed in the last years, regrouping them according to the adopted kind of control strategy. Some experimental results are reported, to show how the control

Basilio Bona; Marina Indri

2005-01-01

381

Temperature-Compensated Sapphire Microwave Resonator  

NASA Technical Reports Server (NTRS)

Sapphire-dielectric-ring microwave resonator operating in "whispering-gallery" electromagnetic mode features differential-thermal-expansion design providing temperature compensation for ultrahigh frequency stability. Designed to minimize frequency fluctuations caused by temperature fluctuations at normal temperature equal to or even somewhat greater than temperature of liquid nitrogen. Ancillary equipment needed for operation smaller and less expensive, and liquid nitrogen used as coolant.

Dick, G. John; Santiago, David G.

1996-01-01

382

Working Toward a Holistic Compensation Model.  

ERIC Educational Resources Information Center

Discusses how the Archdiocese of Louisville has begun taking initiatives to become a more equitable employer. Addresses seven components of compensation including income continuation, deferred income, pay for time not worked, health and accident insurance, loss of job income continuation, and spouse and family income continuation. (MZ)

Reynolds, Brian

2003-01-01

383

Atmospheric radiation  

SciTech Connect

Studies of atmospheric radiative processes are summarized for the period 1987-1990. Topics discussed include radiation modeling; clouds and radiation; radiative effects in dynamics and climate; radiation budget and aerosol effects; and gaseous absorption, particulate scattering and surface reflection. It is concluded that the key developments of the period are a defining of the radiative forcing to the climate system by trace gases and clouds, the recognition that cloud microphysics and morphology need to be incorporated not only into radiation models but also climate models, and the isolation of a few important unsolved theoretical problems in atmospheric radiation.

Harshvardhan, M.R. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

384

A low multiplicative complexity fast recursive DCT-2 algorithm  

E-print Network

A fast Discrete Cosine Transform (DCT) algorithm is introduced that can be of particular interest in image processing. The main features of the algorithm are regularity of the graph and very low arithmetic complexity. The 16-point version of the algorithm requires only 32 multiplications and 81 additions. The computational core of the algorithm consists of only 17 nontrivial multiplications, the rest 15 are scaling factors that can be compensated in the post-processing. The derivation of the algorithm is based on the algebraic signal processing theory (ASP).

Vashkevich, Maxim

2012-01-01

385

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

386

Wavefront sensors and algorithms for adaptive optical systems  

NASA Astrophysics Data System (ADS)

The results of recent works related to techniques and algorithms for wave-front (WF) measurement using Shack-Hartmann sensors show their high efficiency in solution of very different problems of applied optics. The goal of this paper was to develop a sensitive Shack-Hartmann sensor with high precision WF measurement capability on the base of modern technology of optical elements making and new efficient methods and computational algorithms of WF reconstruction. The Shack-Hartmann sensors sensitive to small WF aberrations are used for adaptive optical systems, compensating the wave distortions caused by atmospheric turbulence. A high precision Shack-Hartmann WF sensor has been developed on the basis of a low-aperture off-axis diffraction lens array. The device is capable of measuring WF slopes at array sub-apertures of size 640×640 ?m with an error not exceeding 4.80 arcsec (0.15 pixel), which corresponds to the standard deviation equal to 0.017? at the reconstructed WF with wavelength ? . Also the modification of this sensor for adaptive system of solar telescope using extended scenes as tracking objects, such as sunspot, pores, solar granulation and limb, is presented. The software package developed for the proposed WF sensors includes three algorithms of local WF slopes estimation (modified centroids, normalized cross-correlation and fast Fourierdemodulation), as well as three methods of WF reconstruction (modal Zernike polynomials expansion, deformable mirror response functions expansion and phase unwrapping), that can be selected during operation with accordance to the application.

Lukin, V. P.; Botygina, N. N.; Emaleev, O. N.; Konyaev, P. A.

2010-07-01

387

Algorithm Engineering  

Microsoft Academic Search

Algorithm Engineering is concerned with the design, analysis, implementation, tun- ing, debugging and experimental evaluation of computer programs for solving algorithmic problems. It provides methodologies and tools for developing and engineering efficient al- gorithmic codes and aims at integrating and reinforcing traditional theoretical approaches for the design and analysis of algorithms and data structures.

Camil Demetrescu; Irene FinocchiGiuseppe; F. Italianok

388

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

389

78 FR 67401 - Solicitation of Written Comments by the Military Compensation and Retirement Modernization...  

Federal Register 2010, 2011, 2012, 2013

...MILITARY COMPENSATION AND RETIREMENT MODERNIZATION COMMISSION Solicitation...Comments by the Military Compensation and Retirement Modernization Commission AGENCY: Military Compensation and Retirement Modernization Commission....

2013-11-12

390

78 FR 68097 - Meeting of the Military Compensation and Retirement Modernization Commission  

Federal Register 2010, 2011, 2012, 2013

...MILITARY COMPENSATION AND RETIREMENT MODERNIZATION COMMISSION Meeting of the Military Compensation and Retirement Modernization Commission AGENCY: Military Compensation and Retirement Modernization Commission. ACTION:...

2013-11-13

391

78 FR 70072 - Meeting of the Military Compensation and Retirement Modernization Commission  

Federal Register 2010, 2011, 2012, 2013

...MILITARY COMPENSATION AND RETIREMENT MODERNIZATION COMMISSION Meeting of the Military Compensation and Retirement Modernization Commission AGENCY: Military Compensation and Retirement Modernization Commission. ACTION:...

2013-11-22

392

Effect of board independence on incentive compensation and compensation disclosure : evidence from Europe  

E-print Network

My thesis examines how the lack of board-of-director independence affects the structure and disclosure of executive compensation. I find that European companies with more insiders on their boards grant their executives ...

Muslu, Volkan

2005-01-01

393

Saccadic compensation for reflexive optokinetic nystagmus just as good as compensation for volitional pursuit  

PubMed Central

The natural viewing behavior of moving observers ideally requires target-selecting saccades to be coordinated with automatic gaze-stabilizing eye movements such as optokinetic nystagmus. However, it is unknown whether saccade plans can compensate for reflexive movement of the eye during the variable saccade latency period, and it is unclear whether reflexive nystagmus is even accompanied by extraretinal signals carrying the eye movement information that could potentially underpin such compensation. We show that saccades do partially compensate for optokinetic nystagmus that displaces the eye during the saccade latency period. Moreover, this compensation is as good as for displacements due to voluntary smooth pursuit. In other words, the saccade system appears to be as well coordinated with reflexive nystagmus as it is with volitional pursuit, which in turn implies that extraretinal signals accompany nystagmus and are just as informative as those accompanying pursuit. PMID:25624463

Harrison, James J.; Freeman, Tom C. A.; Sumner, Petroc

2015-01-01

394

Re-Planning for Compensator-Based IMRT with Original Compensators  

SciTech Connect

Compared with multileaf collimator (MLC)-based intensity-modulated radiotherapy (IMRT) for moving targets, compensator-based IMRT has advantages such as shorter beam-on time, fewer monitor units with potentially decreased secondary carcinogenesis risk, better optimization-to-deliverable dose conversion, and often better dose conformity. Some of the disadvantages include additional time for the compensators to be built and delivered, as well as extra cost. Patients undergoing treatment of abdominal cancers often experience weight loss. It would be necessary to account for this change in weight with a new plan and a second set of compensators. However, this would result in treatment delays and added costs. We have developed a method to re-plan the patient using the same set of compensators. Because the weight changes seen with the treatment of abdominal cancers are usually relatively small, a new 4D computed tomography (CT) acquired in the treatment position with markers on the original isocenter tattoos can be registered to the original planning scan. The contours of target volumes from the original scans are copied to the new scan after fusion. The original compensator set can be used together with a few field-in-field (FiF) beams defined by the MLC (or beams with cerrobend blocks for accelerators not equipped with a MLC). The weights of the beams with compensators are reduced so that the FiF or blocked beams can be optimized to mirror the original plan and dose distribution. Seven abdominal cancer cases are presented using this technique. The new plan on the new planning CT images usually has the same dosimetric quality as the original. The target coverage and dose uniformity are improved compared with the plan without FiF/block modification. Techniques combining additional FiF or blocked beams with the original compensators optimize the treatment plans when patients lose weight and save time and cost compared with generating plans with a new set of compensators.

Zhang, Geoffrey [Division of Radiation Oncology and GI Tumor Program, Moffitt Cancer Center, Tampa, FL (United States); Feygelman, Vladimir, E-mail: vladimir.feygelman@moffitt.or [Division of Radiation Oncology and GI Tumor Program, Moffitt Cancer Center, Tampa, FL (United States); Stevens, Craig; Li Weiqi; Leuthold, Susan; Springett, Gregory; Hoffe, Sarah [Division of Radiation Oncology and GI Tumor Program, Moffitt Cancer Center, Tampa, FL (United States)

2011-04-01

395

Controlled Compensation Walls and Compromise Compensation Walls in Garnet Films by the Silicon Annealing Technique  

Microsoft Academic Search

The Si annealing technique has been used on Ga-substituted LPE bubble garnet films to reduce 4piM through zero and produce controlled, well-defined compensation walls. A Si film was deposited on a garnet film, patterned photolithographically, and annealed at 525°C for 40 hours in O2. This produced light and dark Faraday contrast regions separated by compensation walls which were independent of

R. C. Lecraw; R. Wolfe

1974-01-01

396

77 FR 16485 - Compensation, Retirement Programs, and Related Benefits  

Federal Register 2010, 2011, 2012, 2013

...611, 612, 619, 620 and 630 RIN 3052-AC41 Compensation, Retirement Programs, and Related Benefits AGENCY: Farm Credit Administration...require enhanced reporting of senior officer compensation and retirement programs and reporting to shareholders of significant...

2012-03-21

397

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

Code of Federal Regulations, 2011 CFR

...2 2011-07-01 2011-07-01 false Subsequent incarceration of compensation recipient. 301.316 Section 301...Work-Related Physical Impairment or Death § 301.316 Subsequent incarceration of compensation recipient. If a claimant,...

2011-07-01

398

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

Code of Federal Regulations, 2013 CFR

...2 2013-07-01 2013-07-01 false Subsequent incarceration of compensation recipient. 301.316 Section 301...Work-Related Physical Impairment or Death § 301.316 Subsequent incarceration of compensation recipient. If a claimant,...

2013-07-01

399

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

...2 2014-07-01 2014-07-01 false Subsequent incarceration of compensation recipient. 301.316 Section 301...Work-Related Physical Impairment or Death § 301.316 Subsequent incarceration of compensation recipient. If a claimant,...

2014-07-01

400

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

Code of Federal Regulations, 2012 CFR

...2 2012-07-01 2012-07-01 false Subsequent incarceration of compensation recipient. 301.316 Section 301...Work-Related Physical Impairment or Death § 301.316 Subsequent incarceration of compensation recipient. If a claimant,...

2012-07-01

401

28 CFR 301.316 - Subsequent incarceration of compensation recipient.  

Code of Federal Regulations, 2010 CFR

...2 2010-07-01 2010-07-01 false Subsequent incarceration of compensation recipient. 301.316 Section 301...Work-Related Physical Impairment or Death § 301.316 Subsequent incarceration of compensation recipient. If a claimant,...

2010-07-01

402

Temperature compensated sub-metre spatial resolution distributed strain sensor  

Microsoft Academic Search

Temperature compensated strain sensor measurements are demonstrated with strain resolution of 86u? and spatial resolution of 26cms, utilising temperature dependence of spontaneous Raman scattering for temperature compensated sub-metre spatial resolution Brillouin frequency based strain sensor.

Mohammad Belal; Trevor P Newson

2010-01-01

403

17 CFR 229.402 - (Item 402) Executive compensation.  

Code of Federal Regulations, 2010 CFR

...compensation policies and decisions and the most important factors relevant to analysis of those policies and decisions. The Compensation...Registrants are not required to disclose target...performance-related factors considered by...

2010-04-01

404

20 CFR 704.401 - Administration; compensation districts.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Administration; compensation districts. 704...Benefits EMPLOYMENT STANDARDS ADMINISTRATION, DEPARTMENT OF LABOR LONGSHOREMEN'S...Instrumentalities Act § 704.401 Administration; compensation districts. For...

2010-04-01

405

Inductive compensation of operational amplifiers in feedback circuits  

E-print Network

In this thesis I designed, implemented, and tested an integrated-circuit feedback compensator that uses inductors as compensation elements. Introducing inductors as feedback elements makes it possible to implement lead ...

Adams, Douglas Jay Kozak

2010-01-01

406

77 FR 3172 - Compensation, Retirement Programs, and Related Benefits  

Federal Register 2010, 2011, 2012, 2013

...the overall risk and reward structure of compensation...and senior officers' total compensation, as... Balancing financial rewards to senior officers against...institution and the financial rewards to the CEO and senior...institution's projected total long-term...

2012-01-23

407

20 CFR 330.3 - Daily rate of compensation.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Daily rate of compensation. 330.3 Section...BOARD REGULATIONS UNDER THE RAILROAD UNEMPLOYMENT INSURANCE ACT DETERMINATION OF DAILY BENEFIT RATES § 330.3 Daily rate of compensation. (a)...

2010-04-01

408

Fixed structure compensator design using a constrained hybrid evolutionary optimization approach.  

PubMed

This paper presents an efficient technique for designing a fixed order compensator for compensating current mode control architecture of DC-DC converters. The compensator design is formulated as an optimization problem, which seeks to attain a set of frequency domain specifications. The highly nonlinear nature of the optimization problem demands the use of an initial parameterization independent global search technique. In this regard, the optimization problem is solved using a hybrid evolutionary optimization approach, because of its simple structure, faster execution time and greater probability in achieving the global solution. The proposed algorithm involves the combination of a population search based optimization approach i.e. Particle Swarm Optimization (PSO) and local search based method. The op-amp dynamics have been incorporated during the design process. Considering the limitations of fixed structure compensator in achieving loop bandwidth higher than a certain threshold, the proposed approach also determines the op-amp bandwidth, which would be able to achieve the same. The effectiveness of the proposed approach in meeting the desired frequency domain specifications is experimentally tested on a peak current mode control dc-dc buck converter. PMID:24768082

Ghosh, Subhojit; Samanta, Susovon

2014-07-01

409

Atmospheric Chemistry  

NSDL National Science Digital Library

This set of links provides access to resources on atmospheric chemistry, especially acid deposition, air pollution, and air quality. The sites include personal and government pages, universities and research groups, non-governmental organizations and meetings, and products and services. There are also links to related search topics.

410

Improved Load Compensation using Harmonic Compensator in dq0 Current Controller for DSTATCOM  

NASA Astrophysics Data System (ADS)

This paper presents distribution static compensator (DSTATCOM) with dq0 current controller and sine pulse width modulation (SPWM) switching for compensation of unbalanced nonlinear load in distribution system. DSTATCOM, connected in parallel to load at the point of common coupling (PCC), is used for supplying reactive and harmonic components of load current demand. This dq0 current controller is implemented in synchronous reference frame (SRF) rotating at fundamental frequency and consists of harmonic compensation (HC) regulator along with proportional integrator (PI) regulator. HC regulator is realized by number of sinusoidal signal integrators (SSIs) in parallel. The SSI provides high gain for tuned harmonic frequency and helps in minimizing filter current tracking error while compensating for load harmonic currents. Zero-axis controller, which compensates load neutral current and helps in obtaining balanced utility currents, is provided along with d, q controllers. SPWM switching generates inverter gating pulses at constant frequency, which reduces stress levels on VSI switches and simplifies the design of interface filter. Simulation studies of DSTATCOM load compensation with dq0 current controller are carried out in Matlab/Simulink and experimental verification is done using dSpace 1104 with Matlab real-time interface (RTI).

Geddada, Nagesh; Mishra, Mahesh Kumar

2014-12-01

411

Automatic compensation for the errors of a gyroscopic linear integrating accelerometer  

SciTech Connect

The method of least squares and the Kalman filter are the basis for developing algorithms and studying the errors of estimation of the state of a gyroscopic linear integrating accelerometer with digital processing of the data. The article considers the development of algorithms for self-compensation of the errors of a gyroscopic linear integrating accelerometer (GLIA). One of the promising applications of a gyroscopic linear integrating accelerometer is its use as a sensing element for an aviration gravimetric system. At the same time, a GLIA has errors due to nonlinear distortions of the path of the sensing element or gyroscope, the nonzero damping factor of precessional oscillations due to viscous friction moments acting frequency of the precessional oscillations used in the estimation algorithms and the frequency of the precessional oscillations of the gyroscope, and the disturbances that affect the law of motion of the gyroscope. These errors may have an unacceptably large effect (roughly 0.5 g) if not taken into account. The goal here, therefore, is to obtain an algorithm of automatic compensation for the indicated errors. Such a problem has not hitherto been formulated and solved in the theory and practice of gravimetric measurements.

Bezvesil`naya, E.N. [Kiev Polytechnic Institute (Ukraine)

1995-10-01

412

A new approach to harmonic compensation in power systems  

Microsoft Academic Search

A novel approach to compensate for harmonics in power systems is proposed. The approach differs from conventional passive and active filters in its compensation principle. A practical system configuration to implement the approach is presented. It consists of a small-VA-rating PWM (pulsewidth-modulated) converter and a passive filter. The compensation principle is described, and compensation characteristics are examined theoretically and experimentally.

F. Z. Peng; H. Akagi; A. Nabae

1988-01-01

413

Scheme for feed-forward polarization mode dispersion compensation.  

PubMed

We propose a feed-forward polarization mode dispersion (PMD) compensator with three segments that is capable of compensating for the first- and second-order PMD in a transmission fiber. All control parameters are analytically obtained by the PMD concatenated rules. The influence of all possible perturbations on the compensation is investigated with Monte Carlo simulations. The main advantage of our PMD compensation module over the models reported so far is that it shows excellent robustness to all possible perturbations. PMID:15015540

Miao, Houxun; Yang, Changxi

2004-03-01

414

Estimating the compensation strength of coniferous forests for climate change  

NASA Astrophysics Data System (ADS)

Since several years it is been realised that our climate conditions are changing. Scenarios to approximate future conditions as realistic as possible have been constructed and projections for different areas on Earths have been made. However, several complex processes such as aerosols and feedback cycles are not fully understood. One of those feedback cycles is the interactions between different vegetation types and the atmosphere. Each vegetation type has its climate optimum conditions. Changing those a new distribution of plants and trees has to follow or the ecosystem has to adapt. This is usually a lengthy process but critical for coniferous forests such as in boreal regions. Especially the question how much of the changing climate conditions can be compensated by the forest on a shorter time scale. Spracklen et al. (2008) explained that the forest takes up carbon dioxide and increases its leaf area index, thus biomass at future conditions. This will decrease its surface albedo. Compared to a surface without forest the albedo effect was estimated to be +2.3 W m-2 for current cnditions. On the contrary the forest emits notable amounts of volatile organic compounds (VOCs) under stress conditions that significantly take part in atmospheric new particle formation. These new particles grow and result nowadays in a doubling of the cloud condensation number (CCN) over Scandinavia leading to a energy reduction by about -2.9 W m-2, thus a net cooling of -0.6 W m-2 (-0.3 °C) was estimated. This study focusses on the increase of the cooling (compensating) effect at future conditions with elevated temperature conditions. Therefore, we defined four nucleation parameters including the effect of ozone and water vapour on new particle formation as well as the global radiation as a proxy for OH related compounds. In doing so we found a good agreement with field observations for the nucleation parameter which included all effects. Hence, we apply this parameter for expected future conditions. Interestingly if the mean climate is warming by two degrees, the increase in ozone mixing ratio is about as strong as the water vapour mixing ratio at the same relative humidity. Thus both effects cancel each other. Solar radiation is not to be expected to change significantly. Only the terpene emission as precursor for atmospheric particle mass and maybe nucleation remains unbalanced. The emission is known to increase for the most important VOC of coniferous forest by 9% for each temperature increase by one degree. This results in ca. 20% for a mean temperature increase assumed for global change. However, the value is expected to be remarkably larger for boreal regions. If we apply 20% increase in new formed particle number and take into account the reduction during the growth process until the particles reach 50 nm in diameter (ca. +16%), where they can act as CCN, we can approximate the effect of an increase on the indirect (and direct) aerosol radiation effect. Doing so, an additional reduction of 1 W m-2 was calculated. With a simple rule of proportion one can calculate an additional cooling of 0.5 °C. This is actually about a quarter of the actual change at a doubling of carbon dioxide. Thus the forest seems to be able to compensate only about 25% of the expected temperature changes and might reach a critical value within this century in notable areas.

Bonn, Boris; Boy, Michael; Spracklen, Dominick; Kulmala, Markku; Carslaw, Ken; Trawny, Katrin; Jacobi, Stefan

2010-05-01

415

A Method of Springback Prediction and Tool Shape Compensation for Multi-curvature Sheet Metal Bending  

NASA Astrophysics Data System (ADS)

Advanced High Strength Steels (AHSS) are used increasingly in automobile structure parts to reduce the vehicle weight while keeping the safety standard. But their high values of the ratio of strength to Young's modulus cause more springback problems. A method of calculating the compensated tool shape for complex bending shapes is proposed in this paper. The method is composed of 3 steps: firstly the cross-section profile of a part was discretized into points and their corresponding curvatures; then an analytic algorithm based on plastic bending theory is applied to calculate the compensated curvatures of each point; finally, a numerical algorithm based on differential geometry is used to construct the tool shape according to the compensated curvatures of each point. A wave-shaped AHSS part with three different curvatures had been used to evaluate this method. The experimental results showed that the max curvature variance between the actual bending parts and desired shape is less than 4%, which is satisfying for most engineering applications.

Zhou, Chi; Liao, Juan; Zhu, Yin; Chen, Zhenjiao

2010-06-01

416

Kinetic compensation relations: Tools for design in desperation  

Microsoft Academic Search

Compensation relations are obtained for previous studies while assessing whether the compensation phenomena is real or merely a mathematical artifact. Equations concerning compensation from food and bioengineering researchers from the literature are examined as to their possible use as a tool in process design with missing data. Computer flow diagrams are given to explain this procedure and two worked sample

Sibel Özilgen; Mustafa Özilgen

1996-01-01

417

Wind Drift Compensation in Migrating Dragonfiles Pantala (Odonata: Libellulidae)  

Microsoft Academic Search

Q1 Tailwind drift compensation serves to maximize a migrant's flight distance on a given amount of energy, and crosswind drift compensation serves to hold a course true and minimize the distance flown. With full or part com- pensation, airspeeds are predicted to increase with greater crosswind drift. To test whether migrating dragonflies compensated for wind drift, I measured the velocity

Robert B. Srygley

2003-01-01

418

48 CFR 252.217-7004 - Job orders and compensation.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Job orders and compensation. 252.217-7004...Provisions And Clauses 252.217-7004 Job orders and compensation. As prescribed...7104(a), use the following clause: Job Orders and Compensation (MAY 2006)...

2013-10-01

419

48 CFR 252.217-7004 - Job orders and compensation.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Job orders and compensation. 252.217-7004...Provisions And Clauses 252.217-7004 Job orders and compensation. As prescribed...7104(a), use the following clause: JOB ORDERS AND COMPENSATION (MAY 2006)...

2010-10-01

420

48 CFR 252.217-7004 - Job orders and compensation.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Job orders and compensation. 252.217-7004...Provisions And Clauses 252.217-7004 Job orders and compensation. As prescribed...7104(a), use the following clause: JOB ORDERS AND COMPENSATION (MAY 2006)...

2011-10-01

421

48 CFR 252.217-7004 - Job orders and compensation.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Job orders and compensation. 252.217-7004...Provisions And Clauses 252.217-7004 Job orders and compensation. As prescribed...7104(a), use the following clause: Job Orders and Compensation (MAY 2006)...

2012-10-01

422

Presidential Compensation in Higher Education: Policies & Best Practices.  

ERIC Educational Resources Information Center

This book is designed to help leaders of higher education institutions set and negotiate compensation for academic presidents. Its central aim is to strengthen governing board decisions regarding presidential compensation, though it also focuses on other highly compensated institutional officers. The findings are based on interviews with…

Atwell, Robert H.; Wellman, Jane V.

2000-01-01

423

20 CFR 10.15 - May compensation rights be waived?  

Code of Federal Regulations, 2013 CFR

...COMPENSATION ACT, AS AMENDED General Provisions Rights and Penalties § 10.15 May compensation rights be waived? No employer...enter into any agreement, either before or after an injury or death, to waive his or her right to claim compensation under the...

2013-04-01

424

20 CFR 10.15 - May compensation rights be waived?  

...COMPENSATION ACT, AS AMENDED General Provisions Rights and Penalties § 10.15 May compensation rights be waived? No employer...enter into any agreement, either before or after an injury or death, to waive his or her right to claim compensation under the...

2014-04-01

425

20 CFR 10.15 - May compensation rights be waived?  

Code of Federal Regulations, 2010 CFR

...COMPENSATION ACT, AS AMENDED General Provisions Rights and Penalties § 10.15 May compensation rights be waived? No employer...enter into any agreement, either before or after an injury or death, to waive his or her right to claim compensation under...

2010-04-01

426

20 CFR 10.15 - May compensation rights be waived?  

Code of Federal Regulations, 2011 CFR

...COMPENSATION ACT, AS AMENDED General Provisions Rights and Penalties § 10.15 May compensation rights be waived? No employer...enter into any agreement, either before or after an injury or death, to waive his or her right to claim compensation under...

2011-04-01

427

20 CFR 10.15 - May compensation rights be waived?  

Code of Federal Regulations, 2012 CFR

...COMPENSATION ACT, AS AMENDED General Provisions Rights and Penalties § 10.15 May compensation rights be waived? No employer...enter into any agreement, either before or after an injury or death, to waive his or her right to claim compensation under...

2012-04-01

428

28 CFR 345.62 - Inmate accident compensation.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Inmate accident compensation. 345.62 Section 345...Pay and Benefits § 345.62 Inmate accident compensation. An inmate worker...assignments) as specified by the Inmate Accident Compensation Program (28 CFR part...

2011-07-01

429

28 CFR 345.62 - Inmate accident compensation.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Inmate accident compensation. 345.62 Section 345...Pay and Benefits § 345.62 Inmate accident compensation. An inmate worker...assignments) as specified by the Inmate Accident Compensation Program (28 CFR part...

2012-07-01

430

28 CFR 345.62 - Inmate accident compensation.  

...2014-07-01 2014-07-01 false Inmate accident compensation. 345.62 Section 345...Pay and Benefits § 345.62 Inmate accident compensation. An inmate worker...assignments) as specified by the Inmate Accident Compensation Program (28 CFR part...

2014-07-01

431

Rate-Constrained Multi-Hypothesis Motion-Compensated Prediction  

E-print Network

Rate-Constrained Multi-Hypothesis Motion-Compensated Prediction for Video Coding Markus Flierl-hypothesis motion-compensated prediction with multiple reference frames 2. Rate-constrained multi-hypothesis motion on multiple reference frames Markus Flierl: Rate-Constrained Multi-Hypothesis Motion-Compensated Prediction 1

Flierl, Markus

432

Practical studies on bridge compensating technique in fiber optic sensors  

Microsoft Academic Search

The use of optical bridge compensating structure in fiber optic sensor is studied thoroughly in this article. The stability of the compensating structure is essential to achieve good results. A fiber optic pressure sensor based on this compensating structure has been put into practical operation for oil storage measurement in tanks, and the long term stability of the sensor is

Bing Qi; Wei Peng; Jianhua Ding; Junxiu Lin

1998-01-01

433

Self-Programmable PID Compensator for Digitally Controlled SMPS  

E-print Network

Self-Programmable PID Compensator for Digitally Controlled SMPS Zhenyu Zhao and Aleksandar Prodi) that automatically adjusts parameters of PID compensator based on pre-specified bandwidth requirements. The PID at the corner frequency of the power stage. Then, the gain of the PID compensator is found from the oscillations

Prodiæ, Aleksandar

434

The Inverse Kinetics Method and PID Compensation of the  

E-print Network

The Inverse Kinetics Method and PID Compensation of the Annular Core Research Reactor by Benjamin Kinetics Method and PID Compensation of the Annular Core Research Reactor by Benjamin Garnas ABSTRACT Kinetics Method and PID Compensation of the Annular Core Research Reactor by Benjamin Garnas B.S. General

435

Atmospheric Chemistry (Program Description)  

NSF Publications Database

... of Atmospheric Sciences Atmospheric Chemistry Description Supports research to measure and ... on the chemical reactions among atmospheric species; the sources and sinks of important trace gases ...

436

Atmospheric Dust  

NSDL National Science Digital Library

Atmospheric dust storms are common in many of the world's semi-arid and arid regions and can impact local, regional, and even global weather, agriculture, public health, transportation, industry, and ocean health. This module takes a multifaceted approach to studying atmospheric dust storms. The first chapter examines the impacts of dust storms, the physical processes involved in their life cycle, their source regions, and their climatology. The second chapter explores satellite products (notably dust RGBs) and dust models used for dust detection and monitoring, and presents a process for forecasting dust storms. The third and final chapter of the module examines the major types of dust storms: those that are synoptically forced, such as pre- and post-frontal dust storms and those induced by large-scale trade winds; and those caused by mesoscale systems such as downslope winds, gap flow, convection, and inversion downburst storms.

Comet

2012-03-06

437

Electromagnetic transients on compensated lines under corona  

SciTech Connect

This paper presents a digital computational method for the determination of the fast electromagnetic transients propagating on compensated overhead power lines, evoked by internal or external overvoltages, as effected by corona discharges. This approach enables the consideration of series capacitor and shunt reactor compensation. The line model is based on time-domain solution using the Runge-Kutta-Vertner numerical technique to solve a set of simultaneous differential equations. The simulation of the corona discharge uses a model derived from an experimentally measurable voltage-charge hysteresis loop relationship of a line test length. The model can consider any voltage-time function. The validity of the model is checked by comparing its results to corresponding measurements.

Saied, M.M.; Safar, Y.A. (Kuwait Univ. (Kuwait).)

1989-01-01

438

Oblique Alfvén Instabilities Driven by Compensated Currents  

NASA Astrophysics Data System (ADS)

Compensated-current systems created by energetic ion beams are widespread in space and astrophysical plasmas. The well-known examples are foreshock regions in the solar wind and around supernova remnants. We found a new oblique Alfvénic instability driven by compensated currents flowing along the background magnetic field. Because of the vastly different electron and ion gyroradii, oblique Alfvénic perturbations react differently on the currents carried by the hot ion beams and the return electron currents. Ultimately, this difference leads to a non-resonant aperiodic instability at perpendicular wavelengths close to the beam ion gyroradius. The instability growth rate increases with increasing beam current and temperature. In the solar wind upstream of Earth's bow shock, the instability growth time can drop below 10 proton cyclotron periods. Our results suggest that this instability can contribute to the turbulence and ion acceleration in space and astrophysical foreshocks.

Malovichko, P.; Voitenko, Y.; De Keyser, J.

2014-01-01

439

Large antenna measurement and compensation techniques  

NASA Technical Reports Server (NTRS)

Antennas in the range of 20 meters or larger will be an integral part of future satellite communication and scientific payloads. In order to commercially use these large, low sidelobe and multiple-beam antennas, a high level of confidence must be established as to their performance in the 0-g and space environment. It is also desirable to compensate for slowly varying surface distortions which could results from thermal effects. An overview of recent advances in performing rf measurements on large antennas is presented with emphasis given to the application of a space-based far-field range utilizing the Space Shuttle. The concept of surface distortion compensation is discussed by providing numerical and measurement results.

Rahmatsamii, Y.

1989-01-01

440

Workers' compensation managed care: Preliminary findings.  

PubMed

The cost of providing care that is effective to return injured workers to the workplace has risen in recent years in a manner that appears to be out of control in the workers' compensation system. In turn, medical care costs are an important component of the rapidly increasing costs of workers' compensation insurance. A model of health care delivery that emphasizes early intervention and return to work is presented. This model focuses on providing aggressive treatment of injuries that historically have been reported to be extraordinarily expensive. This paper is a case study of a managed care treatment model and presents costs of treatment in the first year of utilization. Medical care costs of 295 cases are compared with state and national figures and are found to be substantially better, especially with regard to soft tissue injuries and injuries that involve days lost from work. PMID:24469866

Matheson, L N; Brophy, R G; Vaughan, K D; Nunez, C; Saccoman, K A

1995-03-01

441

Intonation and Compensation of Fretted String Instruments  

E-print Network

In this paper we present mathematical models and we analyze the physics related to the problem of intonation of musical instruments such as guitars, mandolins and similar, i.e., we study how to produce perfectly in tune notes on these instruments. This analysis begins with the correct fret placement on the instrument fingerboard, following precise mathematical laws, but then it becomes increasingly complicated due to the geometrical deformation of the strings when these instruments are played, and also due to the inharmonic characteristics of the same strings. As a consequence of these factors, perfect intonation of all the notes on the instrument can never be achieved, but complex compensation procedures are introduced and studied to minimize the problem. To test the validity of these compensation procedures, we have performed extensive measurements using standard monochord sonometers and other basic acoustical devices, which confirm the correctness of our theoretical models. In particular, these experimenta...

Varieschi, Gabriele U

2009-01-01

442

76 FR 60132 - Proposed Information Collection (Application for Dependency and Indemnity Compensation by Parent...  

Federal Register 2010, 2011, 2012, 2013

...s), (Including Accrued Benefits and Death Compensation)) Activity: Comment Request...dependency and indemnity compensation, death compensation, and/or accrued benefits...s), (Including Accrued Benefits and Death Compensation), VA Form 21-535....

2011-09-28

443

Atmospheric Modeling  

Microsoft Academic Search

\\u000a Air quality models simulate the atmospheric concentrations and deposition fluxes to the Earth’s surface of air pollutants\\u000a by solving the mass conservation equations that represent the emissions, transport, dispersion, transformations and removal\\u000a of those air pollutants and associated chemical species. Contemporary air quality models can be grouped into two major categories:\\u000a (1) models that calculate the concentrations of air pollutants

Christian Seigneur; Robin Dennis

444

Method of assembling a thermal expansion compensator  

NASA Technical Reports Server (NTRS)

A thermal expansion compensator is provided and includes a first electrode structure having a first surface, a second electrode structure having a second surface facing the first surface and an elastic element bonded to the first and second surfaces and including a conductive element by which the first and second electrode structures electrically and/or thermally communicate, the conductive element having a length that is not substantially longer than a distance between the first and second surfaces.

Determan, William (Inventor); Matejczyk, Daniel Edward (Inventor)

2012-01-01

445

Stereopsis-Guided Brain Shift Compensation  

Microsoft Academic Search

Brain deformation models have proven to be a powerful tool in compensating for soft tissue deformation during image-guided neurosurgery. The accuracy of these models can be improved by incorporating intraoperative measurements of brain motion. We have designed and implemented a passive intraoperative stereo vision system capable of estimating the three-dimensional shape of the surgical scene in near real-time. This intraoperative

Hai Sun; Karen E. Lunn; Hany Farid; Ziji Wu; David W. Roberts; Alexander Hartov; Keith D. Paulsen

2005-01-01

446

Postural compensation for unilateral vestibular loss.  

PubMed

Postural control of upright stance was investigated in well-compensated, unilateral vestibular loss (UVL) subjects compared to age-matched control subjects. The goal was to determine how sensory weighting for postural control in UVL subjects differed from control subjects, and how sensory weighting related to UVL subjects' functional compensation, as assessed by standardized balance and dizziness questionnaires. Postural control mechanisms were identified using a model-based interpretation of medial-lateral center-of-mass body-sway evoked by support-surface rotational stimuli during eyes-closed stance. The surface-tilt stimuli consisted of continuous pseudorandom rotations presented at four different amplitudes. Parameters of a feedback control model were obtained that accounted for each subject's sway response to the surface-tilt stimuli. Sensory weighting factors quantified the relative contributions to stance control of vestibular sensory information, signaling body-sway relative to earth-vertical, and proprioceptive information, signaling body-sway relative to the surface. Results showed that UVL subjects made significantly greater use of proprioceptive, and therefore less use of vestibular, orientation information on all tests. There was relatively little overlap in the distributions of sensory weights measured in UVL and control subjects, although UVL subjects varied widely in the amount they could use their remaining vestibular function. Increased reliance on proprioceptive information by UVL subjects was associated with their balance being more disturbed by the surface-tilt perturbations than control subjects, thus indicating a deficiency of balance control even in well-compensated UVL subjects. Furthermore, there was some tendency for UVL subjects who were less able to utilize remaining vestibular information to also indicate worse functional compensation on questionnaires. PMID:21922014

Peterka, Robert J; Statler, Kennyn D; Wrisley, Diane M; Horak, Fay B

2011-01-01

447

A comparison between different PMD compensation techniques  

Microsoft Academic Search

We quantify the benefits of using different techniques for compensation of polarization mode dispersion (PMD) in fiber-optic communication systems by means of numerical simulations. This is done both with respect to PMD-induced pulse broadening and in terms of system outage probability for different data formats [nonreturn-to-zero (NRZ) and return-to-zero (RZ)]. Attention is focused on simple and relevant single- and double-stage

Henrik Sunnerud; Chongjin Xie; Magnus Karlsson; Robert Samuelsson; Peter A. Andrekson

2002-01-01

448

Postural Compensation for Unilateral Vestibular Loss  

PubMed Central

Postural control of upright stance was investigated in well-compensated, unilateral vestibular loss (UVL) subjects compared to age-matched control subjects. The goal was to determine how sensory weighting for postural control in UVL subjects differed from control subjects, and how sensory weighting related to UVL subjects’ functional compensation, as assessed by standardized balance and dizziness questionnaires. Postural control mechanisms were identified using a model-based interpretation of medial–lateral center-of-mass body-sway evoked by support-surface rotational stimuli during eyes-closed stance. The surface-tilt stimuli consisted of continuous pseudorandom rotations presented at four different amplitudes. Parameters of a feedback control model were obtained that accounted for each subject’s sway response to the surface-tilt stimuli. Sensory weighting factors quantified the relative contributions to stance control of vestibular sensory information, signaling body-sway relative to earth-vertical, and proprioceptive information, signaling body-sway relative to the surface. Results showed that UVL subjects made significantly greater use of proprioceptive, and therefore less use of vestibular, orientation information on all tests. There was relatively little overlap in the distributions of sensory weights measured in UVL and control subjects, although UVL subjects varied widely in the amount they could use their remaining vestibular function. Increased reliance on proprioceptive information by UVL subjects was associated with their balance being more disturbed by the surface-tilt perturbations than control subjects, thus indicating a deficiency of balance control even in well-compensated UVL subjects. Furthermore, there was some tendency for UVL subjects who were less able to utilize remaining vestibular information to also indicate worse functional compensation on questionnaires. PMID:21922014

Peterka, Robert J.; Statler, Kennyn D.; Wrisley, Diane M.; Horak, Fay B.

2011-01-01

449

Long-Range Beam-Beam Compensation in RHIC  

SciTech Connect

In order to avoid the effects of long-range beam-beam interactions which produce beam blow-up and deteriorate beam life time, a compensation scheme with current carrying wires has been proposed. Two long-range beam-beam compensators were installed in RHIC rings in 2006. The effects of the compensators have been experimentally investigated. An indication was observed that the compensators are beneficial to beam life time in measurements performed in RHIC during 2009. In this paper, we report the effects of wire compensator on beam loss and emittance for proton-proton beams at collision energy.

Kim, Hyung Jin; Sen, Tanaji; /Fermilab; Fischer, Wolfram; /Brookhaven

2010-05-01

450

Adaptive optics compensation for propagation through deep turbulence: initial investigation of gradient descent tomography  

NASA Astrophysics Data System (ADS)

To implement adaptive optics compensation for propagation through deep turbulence, the concept of gradient descent tomography has been developed. Here two or more deformable mirrors are controlled by an efficient iterative algorithm that optimizes the integral I2 image-sharpening metric. In this work a difficult case involving imaging over a 2 km path with a Cn2 of 2×10-13m-2/3 is considered. For a wavelength of 1.06?m and a 10-cm-diameter aperture, ?/D is seven times the isoplanatic angle (?0=1.54?rad), and the Rytov number is 5.5. For three points placed along a line spanning approximately 70 isoplanatic patch sizes all three points are compensated somewhat, illustrating that anisoplanatism is addressed. The fact that the corresponding performance improvement ratios are 1.20, 1.34, and 3.26 in the presence of such strong scintillation and anisoplanatism is quite significant.

Tyler, Glenn A.

2006-08-01

451

A robust H.264/AVC video watermarking scheme with drift compensation.  

PubMed

A robust H.264/AVC video watermarking scheme for copyright protection with self-adaptive drift compensation is proposed. In our scheme, motion vector residuals of macroblocks with the smallest partition size are selected to hide copyright information in order to hold visual impact and distortion drift to a minimum. Drift compensation is also implemented to reduce the influence of watermark to the most extent. Besides, discrete cosine transform (DCT) with energy compact property is applied to the motion vector residual group, which can ensure robustness against intentional attacks. According to the experimental results, this scheme gains excellent imperceptibility and low bit-rate increase. Malicious attacks with different quantization parameters (QPs) or motion estimation algorithms can be resisted efficiently, with 80% accuracy on average after lossy compression. PMID:24672376

Jiang, Xinghao; Sun, Tanfeng; Zhou, Yue; Wang, Wan; Shi, Yun-Qing

2014-01-01

452

A Robust H.264/AVC Video Watermarking Scheme with Drift Compensation  

PubMed Central

A robust H.264/AVC video watermarking scheme for copyright protection with self-adaptive drift compensation is proposed. In our scheme, motion vector residuals of macroblocks with the smallest partition size are selected to hide copyright information in order to hold visual impact and distortion drift to a minimum. Drift compensation is also implemented to reduce the influence of watermark to the most extent. Besides, discrete cosine transform (DCT) with energy compact property is applied to the motion vector residual group, which can ensure robustness against intentional attacks. According to the experimental results, this scheme gains excellent imperceptibility and low bit-rate increase. Malicious attacks with different quantization parameters (QPs) or motion estimation algorithms can be resisted efficiently, with 80% accuracy on average after lossy compression. PMID:24672376

Sun, Tanfeng; Zhou, Yue; Shi, Yun-Qing

2014-01-01

453

A study of digital gyro compensation loops. [data conversion routines and breadboard models  

NASA Technical Reports Server (NTRS)

The feasibility is discussed of replacing existing state-of-the-art analog gyro compensation loops with digital computations. This was accomplished by designing appropriate compensation loops for the dry turned TDF gyro, selecting appropriate data conversion and processing techniques and algorithms, and breadboarding the design for laboratory evaluation. A breadboard design was established in which one axis of a Teledyne turned-gimbal TDF gyro was caged digitally while the other was caged using conventional analog electronics. The digital loop was designed analytically to closely resemble the analog loop in performance. The breadboard was subjected to various static and dynamic tests in order to establish the relative stability characteristics and frequency responses of the digital and analog loops. Several variations of the digital loop configuration were evaluated. The results were favorable.

1975-01-01

454

Transducer sensitivity compensation using diagonal preconditioning for time reversal and Tikhonov inverse filtering in acoustic systems.  

PubMed

Filters are commonly used in sound reproduction and communication systems as a means of compensating for the response of the electro-acoustic plant. Two commonly used filter designs in the field of acoustics are the time reversal filter and the Tikhonov inverse filter. In this paper the influence of transducer sensitivities on the performance of these filters is examined. It is shown that the sensitivity of the transducers can negatively affect the performance of the resulting filter. To compensate for the decrease in performance, diagonal preconditioning can be implemented in the system. It is shown that by using diagonal matrices, which minimize the condition number of the system, the loss in performance arising from unbalanced sensitivities is minimized. This paper proposes an algorithm to find such a set of diagonal matrices and results are presented showing the improvements in performance arising from the modified filter design. PMID:16454292

Dumuid, Pierre M; Cazzolato, Ben S; Zander, Anthony C

2006-01-01

455

Magnetic-Flux-Compensated Voltage Divider  

NASA Technical Reports Server (NTRS)

A magnetic-flux-compensated voltage-divider circuit has been proposed for use in measuring the true potential across a component that is exposed to large, rapidly varying electric currents like those produced by lightning strikes. An example of such a component is a lightning arrester, which is typically exposed to currents of the order of tens of kiloamperes, having rise times of the order of hundreds of nanoseconds. Traditional voltage-divider circuits are not designed for magnetic-flux-compensation: They contain uncompensated loops having areas large enough that the transient magnetic fluxes associated with large transient currents induce spurious voltages large enough to distort voltage-divider outputs significantly. A drawing of the proposed circuit was not available at the time of receipt of information for this article. What is known from a summary textual description is that the proposed circuit would contain a total of four voltage dividers: There would be two mixed dividers in parallel with each other and with the component of interest (e.g., a lightning arrester), plus two mixed dividers in parallel with each other and in series with the component of interest in the same plane. The electrical and geometric configuration would provide compensation for induced voltages, including those attributable to asymmetry in the volumetric density of the lightning or other transient current, canceling out the spurious voltages and measuring the true voltage across the component.

Mata, Carlos T.

2005-01-01

456

Direct Lorentz force compensation flowmeter for electrolytes  

NASA Astrophysics Data System (ADS)

A simplified method of contactless Lorentz force (LF) measurements for flow meters on electrolytes is described and realized. Modification and comparative representation are discussed against recently well-developed methods. Based on the catapult effect, that current carrying conductor experiences a repulsive force in a magnetic field, we demonstrate force measurement method of LF velocimetry applications by commonly known "electromagnetic force" compensation principle. Measurement approach through zero point stability is considered to minimize mechanical influences and avoid gravimetric uncertainties. Here, the current carrying wires are static fixed in the vicinity of magnet system at zero point stable position, while occurring deflection of magnets by electrolyte flow is compensated by external applied current within wires. Measurements performed by developed servo-system which drives control loop by means of optical position sensor for simplified (i) single wire and (ii) coil-like extended compensation schemes. Guided by experiments on electrolyte flow, we demonstrate the applicability of adopted principle for conductivities ranging from 2 to 20 S/m. Further improvements are discussed in agreement with the parameters of demonstration setup, straightforward theory, and experimental results. We argue that this method is potentially suitable for: (a) applications with higher conductivity like molten metal (order of 106 S/m) assuming spatial configuration of setup and (b) for lower range of conductivity (below 1 S/m) while this is strongly subject to stiffness of system and noise mainly mechanical and thermal radiations.

Vasilyan, S.; Froehlich, Th.

2014-12-01

457

Germany to Compensate Nazi Slave Laborers  

NSDL National Science Digital Library

On Wednesday May 30, 2001, German lawmakers voted nearly unanimously to remove the final legal obstacle to free a $4.5 billion fund to begin to compensate over 1.5 million survivors of Nazi slave labor camps. Germany has already paid over $60 billion in restitution to victims of the Nazis, but this is the first time that slave labor has been specifically included. German companies have long admitted they used slave labor during the Nazi regime but insist they did so only because they'd been pressured by the Nazis. However, 6,300 German companies have already pledged contributions to the industry fund drive, which was started three years ago to stave off lawsuits from American firms against some of Germany's biggest manufacturers including Volkswagen, BMW, and Dailmer-Benz for their participation in slave labor in the earlier half of the 20th century. The plan for compensation calls for two categories of slave labor: $6,600 will be given to those forced to work under life-threatening conditions including concentration camps, and $2,200 will be given to the victims who were forced to work under "less onerous conditions." While these payment are seen as a merely symbolic gesture, German Chancellor Gerhard Schroeder explained that the compensation "sends a signal that Germany is fully conscious of the terrible crimes of its past, and will remain so."

Missner, Emily D.

458

Optical compensation device for chest film radiography  

NASA Astrophysics Data System (ADS)

Although chest radiography is the most commonly performed radiographic examination and one of the most valuable and cost-effective studies in medicine it suffers from relatively high error rates in both missing pathology and false positive interpretations. Detectability of lung nodules and other structures in underpenetrated regions of the chest film can be improved by both exposure and optical compensation but current compensation systems require major capital cost or a significant change in normal clinical practice. A new optical compensation system called the " Intelligent X-Ray Illuminator" (IXI) automatically and virtually instantaneously generates a patient-specific optical unsharp mask that is projected directly on a radiograph. When a radiograph is placed on the IXI which looks much like a conventional viewbox it acquires a low-resolution electronic image of this film from which the film transmission is derived. The transmission information is inverted and blurred in an image processor to form an unsharp mask which is fed into a spatial light modulator (SLM) placed between a light source and the radiograph. The SLM tailors the viewbox luminance by decreasing illumination to underexposed (i. e. transmissive) areas of the radiograph presenting the observer with an optically unsharp-masked image. The IXI uses the original radiograph and will allow it to be viewed on demand with conventional (uniform illumination. Potentially the IXI could introduce the known beneficial aspects of optical unsharp masking into radiology at low capital

Gould, Robert G.; Hasegawa, Bruce H.; DeForest, Sherman E.; Schmidt, Gregory W.; Hier, Richard G.

1990-07-01

459

Validation of atmospheric correction over the oceans  

NASA Astrophysics Data System (ADS)

By validation of atmospheric correction, we mean quantification of the uncertainty expected to be associated with the retrieval of the water-leaving radiance from the measurement of the total radiance exiting the ocean-atmosphere system. This uncertainty includes that associated with the measurement or estimation of auxiliary data required for the retrieval process, for example, surface wind speed, surface atmospheric pressure, and total ozone concentration. For a definitive validation this quantification should be carried out over the full range of atmospheric types expected to be encountered. However, funding constraints require that the individual validation campaigns must be planned to address the individual components of the atmospheric correction algorithm believed to represent the greatest potential sources of error. In this paper we develop a strategy for validation of atmospheric correction over the oceans that is focused on EOS/MODIS. We also provide a description of the instrumentation and methods to be used in the implementation of the plan.

Clark, D. K.; Gordon, H. R.; Voss, K. J.; Ge, Y.; Broenkow, W.; Trees, C.

1997-07-01

460

Compensating for the harms of family violence: statutory barriers in Australian victims of crime compensation schemes.  

PubMed

This article considers the compensative capacity of the victims of crime statutory schemes that are present in all eight Australian jurisdictions for primary victims of family violence. It argues that the recommendations of the Final Report on Family Violence conducted jointly by the Australian Law Reform Commission and the New South Wales Law Reform Commission in 2010, although a positive step, are insufficient to facilitate meaningful compensation to victims of family violence. In addition to the primary limitations identified by the Commissions--a requirement to report the crime to the police within a reasonable time and a requirement for multiple acts of violence to be reduced to a single act if they are related--there are other statutory barriers that disproportionately disadvantage victims of family violence. These include time limitation provisions, a requirement to report the crime to police, the restriction of compensation to prescribed categories of loss which exclude many of the social, vocational, emotional and psychological harms suffered by victims of family violence, and significant cut-backs on the non-economic component of the schemes. This article further argues that the statutory barriers cumulatively contribute to the perception of a crime as an isolated event perpetrated by a deviant individual. The article recommends that specific provisions for family violence victims should be introduced into all schemes including three categories of compensation not tied to criminal offences but rather the different forms of family violence, with a generous compensation range, and no requirement for proof of injury. PMID:25341328

Forster, Christine

2014-09-01

461

EUV multilayer defect compensation (MDC): latest progress on model and compensation methods  

NASA Astrophysics Data System (ADS)

Making a multilayer defect-free extreme ultraviolet (EUV) blank is not possible today, and is unlikely to happen in the next few years. The method proposed by Luminescent is to compensate effects of multilayer defects on images by modifying the absorber patterns. Progress in MDC is the subject of this paper. The multilayer growth model was calibrated using real data - the top layer profile captured by AFM and cross section captured by TEM for programmed defects. Multilayer defect profiles on repair sites were recovered by applying inverse methods with the calibrated model to AFM surface scans. The recovered defect profiles were fed into the MDC engine to calculate modified absorber patterns that would compensate for the defects. Further, new methods to compensate for phase errors by depositing materials or peeling multilayers in addition to absorber modifications have been developed. Different options of multilayer peeling for compensating phase error are also evaluated through simulation. A case study was performed to find out what is the maximum pit and bump defects that can be compensated by all options available. It shows absorber pattern modification plus material deposition is the most effective option for pit defect, while absorber pattern modification plus layer-by-layer multilayer peeling is the most effective option for bump defect. Either of these methods can fix defects up to four times larger than those that can be fixed by only modifying absorber patterns near them.

Pang, Linyong; Satake, Masaki; Li, Ying; Hu, Peter; Peng, Danping; Chen, Dongxue; Tolani, Vikram

2013-09-01

462

One-way radio frequency dissemination through the atmosphere using two optical carriers.  

PubMed

A method of transferring an RF reference frequency through the turbulent atmosphere is presented. Using two optical wavelengths close to each other can compensate for the influence of the atmospheric piston error. The influence of the atmosphere on the phase of the optical signal is calculated together with the remaining error by transferring two carriers. The system was implemented in a laboratory test-bed, and stability measurements are shown. PMID:22940994

Mata-Calvo, Ramon; Giggenbach, Dirk

2012-09-01

463

Fuzzy control algorithm for universal active filter  

Microsoft Academic Search

In this paper, a fuzzy algorithm is employed to control a three-phase unified power quality conditioner (UPQC). The UPQC is an active filter (AF) and it compensates the reactive power and harmonics in both the voltage and current caused by nonlinear loads. The UPQC makes use of two back-to-back connected IGBT-based voltage source inverters (VSIs) with a common DC bus.

B. N. Singh; H. Chandra; K. Al-Haddad

1998-01-01

464

PID Parameters Optimization by Using Genetic Algorithm  

E-print Network

Time delays are components that make time-lag in systems response. They arise in physical, chemical, biological and economic systems, as well as in the process of measurement and computation. In this work, we implement Genetic Algorithm (GA) in determining PID controller parameters to compensate the delay in First Order Lag plus Time Delay (FOLPD) and compare the results with Iterative Method and Ziegler-Nichols rule results.

Mirzal, Andri; Furukawa, Masashi

2012-01-01

465

Atmospheric science  

NASA Technical Reports Server (NTRS)

The following types of experiments for a proposed Space Station Microgravity Particle Research Facility are described: (1) growth of liquid water drop populations; (2) coalescence; (3) drop breakup; (4) breakup of freezing drops; (5) ice nucleation for large aerosols or bacteria; (6) scavenging of gases, for example, SO2 oxidation; (7) phoretic forces, i.e., thermophoresis versus diffusiophoresis; (8) Rayleigh bursting of drops; (9) charge separation due to collisions of rimed and unrimed ice; (10) charged drop dynamics; (11) growth of particles in other planetary atmospheres; and (12) freezing and liquid-liquid evaporation. The required capabilities and desired hardware for the facility are detailed.

Hamill, Patrick; Ackerman, Thomas; Clarke, Antony; Goodman, Jindra; Levin, Zev; Tomasko, Martin; Toon, O. Brian; Whitten, Robert

1987-01-01

466

Real-time compensation of phase distortions by digital phase conjugation using CCD and liquid crystal panel.  

PubMed

A video-rate optical phase conjugator using an image sensor and a liquid crystal panel that operated at 30 Hz was developed and its temporal characteristic was studied. Strong air turbulence of atmospheric structure constant, Cn=6.3×10(-7)??[m(-1/3)], was successfully compensated, reducing beam dancing by a factor of 2. To our knowledge, this is the first report demonstrating real-time wavefront correction by digital phase conjugation using commercial devices. PMID:24921130

Kawakami, Kotomi; Uchida, Shigeaki; Okamura, Hideki

2014-06-10

467

T2 Relaxometry with Indirect Echo Compensation from Highly Undersampled Data  

PubMed Central

Purpose To develop an algorithm for fast and accurate T2 estimation from highly undersampled multi-echo spin-echo (MESE) data. Methods The algorithm combines a model-based reconstruction with a signal decay based on the slice-resolved extended phase graph (SEPG) model with the goal of reconstructing T2 maps from highly undersampled radial MESE data with indirect echo compensation. To avoid problems associated with the nonlinearity of the SEPG model, principal component decomposition is used to linearize the signal model. The proposed CUrve Reconstruction via pca-based Linearization with Indirect Echo compensation (CURLIE) algorithm is used to estimate T2 curves from highly undersampled data. T2 maps are obtained by fitting the curves to the SEPG model. Results Results on phantoms showed T2 biases (1.9% to 18.4%) when indirect echoes are not taken into account. The T2 biases were reduced (<3.2%) when the CURLIE reconstruction was performed along with SEPG fitting even for high degrees of undersampling (4% sampled). Experiments in vivo for brain, liver and heart followed the same trend as the phantoms. Conclusion The CURLIE reconstruction combined with SEPG fitting enables accurate T2 estimation from highly undersampled MESE radial data thus, yielding a fast T2 mapping method without errors caused by indirect echoes. PMID:23165796

Huang, Chuan; Bilgin, Ali; Barr, Tomoe; Altbach, Maria I.

2012-01-01

468

Medical image compression using cubic spline interpolation with bit-plane compensation  

NASA Astrophysics Data System (ADS)

In this paper, a modified medical image compression algorithm using cubic spline interpolation (CSI) is presented for telemedicine applications. The CSI is developed in order to subsample image data with minimal distortion and to achieve compression. It has been shown in literatures that the CSI can be combined with the JPEG algorithms to develop a modified JPEG codec, which obtains a higher compression ratio and a better quality of reconstructed image than the standard JPEG. However, this modified JPEG codec will lose some high-frequency components of medical images during compression process. To minimize the drawback arose from loss of these high-frequency components, this paper further makes use of bit-plane compensation to the modified JPEG codec. The bit-plane compensation algorithm used in this paper is modified from JBIG2 standard. Experimental results show that the proposed scheme can increase 20~30% compression ratio of original JPEG medical data compression system with similar visual quality. This system can reduce the loading of telecommunication networks and is quite suitable for low bit-rate telemedicine applications.

Truong, Trieu-Kien; Chen, Shi-Huang; Lin, Tsung-Ching

2007-03-01

469