Science.gov

Sample records for atmospheric compensation algorithm

  1. Comparison of swarm intelligence algorithms in atmospheric compensation for free space optical communication

    NASA Astrophysics Data System (ADS)

    Li, Zhaokun; Cao, Jingtai; Liu, Wei; Feng, Jianfeng; Zhao, Xiaohui

    2015-03-01

    We use conventional adaptive optical system to compensate atmospheric turbulence in free space optical (FSO) communication system under strong scintillation circumstances, undesired wave-front measurements based on Shark-Hartman sensor (SH). Since wavefront sensor-less adaptive optics is a feasible option, we propose several swarm intelligence algorithms to compensate the wavefront aberration from atmospheric interference in FSO and mainly discuss the algorithm principle, basic flows, and simulation result. The numerical simulation experiment and result analysis show that compared with SPGD algorithm, the proposed algorithms can effectively restrain wavefront aberration, and improve convergence rate of the algorithms and the coupling efficiency of receiver in large extent.

  2. Swarm intelligence for atmospheric compensation in free space optical communication-Modified shuffled frog leaping algorithm

    NASA Astrophysics Data System (ADS)

    Li, Zhaokun; Cao, Jingtai; Zhao, Xiaohui; Liu, Wei

    2015-03-01

    A conventional adaptive optics (AO) system is widely used to compensate atmospheric turbulence in free space optical (FSO) communication systems, but wavefront measurements based on phase-conjugation principle are not desired under strong scintillation circumstances. In this study we propose a novel swarm intelligence optimization algorithm, which is called modified shuffled frog leaping algorithm (MSFL), to compensate the wavefront aberration. Simulation and experiments results show that MSFL algorithm performs well in the atmospheric compensation and it can increase the coupling efficiency in receiver terminal and significantly improve the performance of the FSO communication systems.

  3. A spectral climatology for atmospheric compensation

    NASA Astrophysics Data System (ADS)

    Powell, John H.; Resmini, Ronald G.

    2014-06-01

    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.

  4. A Spectral Climatology for Atmospheric Compensation of Hyperspectral Imagery

    NASA Astrophysics Data System (ADS)

    Powell, John H.

    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 research 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 observations and modeled data. The empirical techniques for extracting the coefficients and correcting for small nonlinear features, the modeling methods used to standardize the coefficients across varying collection and illumination geometries, and the resulting comparisons of adjusted coefficients are presented. The resulting climatological database is analyzed to show that common spectral similarity metrics can be used to separate the climatological classes to a degree of detail commensurate with the modest size and range of the imaging conditions comprising the study. The study closes with a notional application example and a discussion of the potential benefits, shortfalls and future work to fully develop the new technique.

  5. Assimilation of nontraditional datasets to improve atmospheric compensation

    NASA Astrophysics Data System (ADS)

    Kelly, Michael A.; Osei-Wusu, Kwame; Spisz, Thomas S.; Strong, Shadrian; Setters, Nathan; Gibson, David M.

    2012-06-01

    Detection and characterization of space objects require the capability to derive physical properties such as brightness temperature and reflectance. These quantities, together with trajectory and position, are often used to correlate an object from a catalogue of known characteristics. However, retrieval of these physical quantities can be hampered by the radiative obscuration of the atmosphere. Atmospheric compensation must therefore be applied to remove the radiative signature of the atmosphere from electro-optical (EO) collections and enable object characterization. The JHU/APL Atmospheric Compensation System (ACS) was designed to perform atmospheric compensation for long, slant-range paths at wavelengths from the visible to infrared. Atmospheric compensation is critically important for airand ground-based sensors collecting at low elevations near the Earth's limb. It can be demonstrated that undetected thin, sub-visual cirrus clouds in the line of sight (LOS) can significantly alter retrieved target properties (temperature, irradiance). The ACS algorithm employs non-traditional cirrus datasets and slant-range atmospheric profiles to estimate and remove atmospheric radiative effects from EO/IR collections. Results are presented for a NASA-sponsored collection in the near-IR (NIR) during hypersonic reentry of the Space Shuttle during STS-132.

  6. Atmospheric Compensation for Uplink Arrays via Radiometry

    NASA Technical Reports Server (NTRS)

    Nessel, James A.; Acosta, Roberto J.

    2010-01-01

    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.

  7. Generic algorithms for motion compensation and transformation

    NASA Astrophysics Data System (ADS)

    Richter, Henryk; Stabernack, Benno; Mller, Erika

    2008-02-01

    In this paper, we propose algorithms that map the low-level motion compensation and transformation functions of MPEG-1/2, H.263/MPEG-4 ASP and H.264/MPEG-4 AVC video codecs onto common workflows. This way, a single discrete implementation of luma prediction, chroma prediction and residual transform stages is sufficient for all covered video coding standards. The proposed luma prediction is based on 44 blocks to cover the H.264 specifications as well as the elder standards. The design consists of a singular four stage pipeline for two block interpolation and two block averaging stages. Targeted for hardware implementation, a strictly linear execution is provided, avoiding branch operations. The algorithmic behavior is entirely dictated by the contents of the parameter ROM. Since chrominance prediction must cover blocks as small as 22 pixels, a distinct operation is proposed for chroma. The bilinear operation scheme in H.264 is able to carry out the operations for the elder standards with minor changes only. In H.264, the classic 88 DCT transformation was replaced by a simplified 44 integer transform, based on a heavily quantized DCT scheme. By modifications of a well-known multiplier-adder-based scheme, a generalized transformation stage can be derived.

  8. A Novel Motion Compensation Algorithm for Acoustic Radiation Force Elastography

    PubMed Central

    Hsu, Stephen J.; Trahey, Gregg E.

    2009-01-01

    A novel method of physiological motion compensation for use with radiation force elasticity imaging has been developed. The method utilizes a priori information from finite element method models of the response of soft tissue to impulsive radiation force to isolate physiological motion artifacts from radiation force-induced displacement fields. The new algorithm is evaluated in a series of clinically realistic imaging scenarios, and its performance is compared to that achieved with previously described motion compensation algorithms. Though not without limitations, the new model-based motion compensation algorithm performs favorably in many circumstances and may be a logical choice for use with in vivo abdominal imaging. PMID:18519218

  9. Template based illumination compensation algorithm for multiview video coding

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  10. Broadband beamforming compensation algorithm in CI front-end acquisition

    PubMed Central

    2013-01-01

    Background To increase the signal to noise ratio (SNR) and to suppress directional noise in front-end signal acquisition, microphone array technologies are being applied in the cochlear implant (CI). Due to size constraints, the dual microphone-based system is most suitable for actual application. However, direct application of the array technology will result in the low frequency roll-off problem, which can noticeably distort the desired signal. Methods In this paper, we theoretically analyze the roll-off characteristic on the basis of CI parameters and present a new low-complexity compensation algorithm. We obtain the linearized frequency response of the two-microphone array from modeling and analysis for further algorithm realization. Realization and results Linear method was used to approximate the theoretical response with adjustable delay and weight parameters. A CI dual-channel hardware platform is constructed for experimental research. Experimental results show that our algorithm performs well in compensation and realization. Discussions We discuss the effect from environment noise. Actual daily noise with more low-frequency energy will weaken the algorithm performance. A balance between low-frequency distortion and corresponding low-frequency noise need to be considered. Conclusions Our novel compensation algorithm uses linear function to obtain the desired system response, which is a low computational-complexity method for CI real-time processing. Algorithm performance is tested in CI CIS modulation and the influence of experimental distance and environmental noise were further analyzed to evaluate algorithm constraint. PMID:23442782

  11. Improved neural network algorithm: application in the compensation of wavefront distortion

    NASA Astrophysics Data System (ADS)

    Zhou, Zhou; Yuan, Xiuhua; Wang, Jin

    2008-12-01

    A Free Space Optical Communication (FSO) system transmits modulated light through atmospheric media. Because of the uneven distribution of refractive index result from atmospheric turbulence, the phase distribution of light is changed leading to distortion of wavefront and requiring reconstruction at the receiver. However, current wavefront compensation relies on channel modeling which has difficulties in extracting channel information from highly random turbulent atmosphere. In this paper, a wavefront reconstruction system based on neural network algorithm is constructed. The neural network requires little channel information but predicts distortion by past experience. Then, distorted phase distribution is adaptively revised when light passes through a piezoelectric ceramic deformable mirror controlled by neural network. Dynamic study factors are added to neural network algorithm as improvement which adjusts the study speed of the system according to turbulence intensity providing best result between respond time and reconstruction accuracy. In addition, light transmitted in atmospheric channel is studied.

  12. A relational database management system for atmospheric compensation research

    NASA Astrophysics Data System (ADS)

    Powell, John; Erukulla, Gautami; Buhisi, Mohamad; Velauthapillai, Balendran

    2011-04-01

    Atmospheric compensation is a key step in the processing of most remotely sensed Earth images, but is particularly important in Hyperspectral Imagery (HSI) analysis. The state of atmospheric sensible variables at the time of the image is a key driver of atmospheric path radiance and transmissivity effects. A thorough assessment of the state of the atmosphere is rarely conducted in HSI analysis, however, even in rigorous scientific literature. This is due in part to the historical lack of meteorological data associated with imagery collects, and the difficulty in accessing and analyzing the data that is available. With the expanding availability of online climatological and observational atmospheric data and the advent of web enabled search and retrieval tools, easy access to worldwide atmospheric data relevant to atmospheric compensation is possible. In this project, a Relational Database Management System (RDBMS) is developed that automatically retrieves relevant atmospheric data from several online data stores based on input image metadata. The RBDMS provides researchers with a single, easily accessible repository of meteorological data to aid in researching atmospheric effects. System design considerations and available data sources are reviewed, and example research applications are presented.

  13. Application of Least Mean Square Algorithms to Spacecraft Vibration Compensation

    NASA Technical Reports Server (NTRS)

    Woodard , Stanley E.; Nagchaudhuri, Abhijit

    1998-01-01

    This paper describes the application of the Least Mean Square (LMS) algorithm in tandem with the Filtered-X Least Mean Square algorithm for controlling a science instrument's line-of-sight pointing. Pointing error is caused by a periodic disturbance and spacecraft vibration. A least mean square algorithm is used on-orbit to produce the transfer function between the instrument's servo-mechanism and error sensor. The result is a set of adaptive transversal filter weights tuned to the transfer function. The Filtered-X LMS algorithm, which is an extension of the LMS, tunes a set of transversal filter weights to the transfer function between the disturbance source and the servo-mechanism's actuation signal. The servo-mechanism's resulting actuation counters the disturbance response and thus maintains accurate science instrumental pointing. A simulation model of the Upper Atmosphere Research Satellite is used to demonstrate the algorithms.

  14. New inverse synthetic aperture radar algorithm for translational motion compensation

    NASA Astrophysics Data System (ADS)

    Bocker, Richard P.; Henderson, Thomas B.; Jones, Scott A.; Frieden, B. R.

    1991-10-01

    Inverse synthetic aperture radar (ISAR) is an imaging technique that shows real promise in classifying airborne targets in real time under all weather conditions. Over the past few years a large body of ISAR data has been collected and considerable effort has been expended to develop algorithms to form high-resolution images from this data. One important goal of workers in this field is to develop software that will do the best job of imaging under the widest range of conditions. The success of classifying targets using ISAR is predicated upon forming highly focused radar images of these targets. Efforts to develop highly focused imaging computer software have been challenging, mainly because the imaging depends on and is affected by the motion of the target, which in general is not precisely known. Specifically, the target generally has both rotational motion about some axis and translational motion as a whole with respect to the radar. The slant-range translational motion kinematic quantities must be first accurately estimated from the data and compensated before the image can be focused. Following slant-range motion compensation, the image is further focused by determining and correcting for target rotation. The use of the burst derivative measure is proposed as a means to improve the computational efficiency of currently used ISAR algorithms. The use of this measure in motion compensation ISAR algorithms for estimating the slant-range translational motion kinematic quantities of an uncooperative target is described. Preliminary tests have been performed on simulated as well as actual ISAR data using both a Sun 4 workstation and a parallel processing transputer array. Results indicate that the burst derivative measure gives significant improvement in processing speed over the traditional entropy measure now employed.

  15. Genetic algorithm optimized triply compensated pulses in NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Manu, V. S.; Veglia, Gianluigi

    2015-11-01

    Sensitivity and resolution in NMR experiments are affected by magnetic field inhomogeneities (of both external and RF), errors in pulse calibration, and offset effects due to finite length of RF pulses. To remedy these problems, built-in compensation mechanisms for these experimental imperfections are often necessary. Here, we propose a new family of phase-modulated constant-amplitude broadband pulses with high compensation for RF inhomogeneity and heteronuclear coupling evolution. These pulses were optimized using a genetic algorithm (GA), which consists in a global optimization method inspired by Nature's evolutionary processes. The newly designed ? and ? / 2 pulses belong to the 'type A' (or general rotors) symmetric composite pulses. These GA-optimized pulses are relatively short compared to other general rotors and can be used for excitation and inversion, as well as refocusing pulses in spin-echo experiments. The performance of the GA-optimized pulses was assessed in Magic Angle Spinning (MAS) solid-state NMR experiments using a crystalline U-13C, 15N NAVL peptide as well as U-13C, 15N microcrystalline ubiquitin. GA optimization of NMR pulse sequences opens a window for improving current experiments and designing new robust pulse sequences.

  16. Control algorithms for aerobraking in the Martian atmosphere

    NASA Astrophysics Data System (ADS)

    Shipley, Buford Wiley, Jr.

    1991-02-01

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

  17. Atmospheric-turbulence compensation experiments using synthetic beacons

    NASA Astrophysics Data System (ADS)

    Zollars, Byron G.

    Recent experiments conducted at the Maui Field Site of MIT's Lincoln Laboratory have indicated that the Rayleigh backscatter from laser beams focused at altitudes of up to 8 km can generate synthetic beacons applicable to adaptive optics systems, thereby relaxing requirements for object brightness. Synthetic-beacon adaptive optics technology is widely applicable, in such fields as space surveillance, ballistic-missile beam-weapon defenses, antisatellite beam weapons, and ground-based astronomy. Attention is given to Rayleigh beacon-laser requirements, sources of error in synthetic-beacon adaptive optics, and the design and operation of the Short-Wavelength Adaptive Techniques adaptive-optics system for atmospheric compensation experiments.

  18. Error compensation algorithm for patient positioning robotics system

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2005-10-01

    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.

  20. Sensor Saturation Compensated Smoothing Algorithm for Inertial Sensor Based Motion Tracking

    PubMed Central

    Dang, Quoc Khanh; Suh, Young Soo

    2014-01-01

    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

  1. Atmospheric correction algorithm for hyperspectral imagery

    NASA Astrophysics Data System (ADS)

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

    1999-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  3. An improved dynamic compensation algorithm for rhodium self-powered neutron detectors

    SciTech Connect

    Kantrowitz, M.L.

    1987-02-01

    Rhodium self-powered neutron detectors are utilized in many pressurized water reactors to determine the neutronic behaviour within the core. In order to compensate for the inherent time delay associated with the response of these detectors, a dynamic compensation algorithm is currently used in Combustion Engineering plants to reconstruct the dynamic flux signal which is being sensed by the rhodium detectors. This paper describes a new dynamic compensation algorithm, based on Kalman filtering, which improves on the noise gain and response time characteristics of the algorithm currently used, and offers the possibility of significantly expanding the capabilities of the present in-core detector system without a major hardware investment.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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.

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

    PubMed

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

    2013-06-20

    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

  6. Springback compensation algorithm for tool design in creep age forming of large aluminum alloy plate

    NASA Astrophysics Data System (ADS)

    Xu, Xiaolong; Zhan, Lihua; Huang, Minghui

    2013-12-01

    The creep unified constitutive equations, which was built based on the age forming mechanism of aluminum alloy, was integrated with the commercial finite element analysis software MSC.MARC via the user defined subroutine, CREEP, and the creep age forming process simulations for7055 aluminum alloy plate parts were conducted. Then the springback of the workpiece after forming was calculated by ATOS Professional Software. Based on the combination between simulation results and calculation of springback by ATOS for the formed plate, a new weighted springback compensation algorithm for tool surface modification was developed. The compensate effects between the new algorithm and other overall compensation algorithms on the tool surface are compared. The results show that, the maximal forming error of the workpiece was reduced to below 0.2mm after 5 times compensations with the new weighted algorithm, while error rebound phenomenon occurred and the maximal forming error cannot be reduced to 0.3mm even after 6 times compensations with fixed or variable compensation coefficient, which are based on the overall compensation algorithm.

  7. A Comprehensive Study of Three Delay Compensation Algorithms for Flight Simulators

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  8. Multi-frame atmospheric compensation under moving camera conditions

    NASA Astrophysics Data System (ADS)

    Paolini, Aaron L.; Bodnar, Michael R.; Ortiz, Fernando; Price, Daniel K.

    2011-06-01

    Multi-frame algorithms for the removal of atmospheric turbulence have proven effective under ideal conditions where the scene remains static; however, movement of the camera across a scene often introduces undesirable effects that degrade the quality of processed imagery to the point where it becomes unusable. This paper discusses the development of two solutions to this problem, each with different computational costs and levels of efficacy. We discuss a solution to this problem that uses robust registration methods to align a window of input images to each other and processes them to obtain a single improved frame, repeating the sequence of realignment and processing each time a new frame arrives. While this approach produces high quality results, the associated computational cost precludes real-time implementation, even on accelerated platforms. An alternative solution involves measuring scene movement through lightweight registration and quantification. Registration results are used to make a global determination of "safe" approaches to processing in order to avoid degraded results. This particular method is computationally inexpensive at the cost of efficacy. We discuss the performance of both of these modifications against the original, uncompensated algorithm in terms of computational cost and quality of output imagery. Additionally, we will briefly discuss future goals which aim to minimize additional computation while maximizing processing efficacy.

  9. A Novel Control algorithm based DSTATCOM for Load Compensation

    NASA Astrophysics Data System (ADS)

    R, Sreejith; Pindoriya, Naran M.; Srinivasan, Babji

    2015-11-01

    Distribution Static Compensator (DSTATCOM) has been used as a custom power device for voltage regulation and load compensation in the distribution system. Controlling the switching angle has been the biggest challenge in DSTATCOM. Till date, Proportional Integral (PI) controller is widely used in practice for load compensation due to its simplicity and ability. However, PI Controller fails to perform satisfactorily under parameters variations, nonlinearities, etc. making it very challenging to arrive at best/optimal tuning values for different operating conditions. Fuzzy logic and neural network based controllers require extensive training and perform better under limited perturbations. Model predictive control (MPC) is a powerful control strategy, used in the petrochemical industry and its application has been spread to different fields. MPC can handle various constraints, incorporate system nonlinearities and utilizes the multivariate/univariate model information to provide an optimal control strategy. Though it finds its application extensively in chemical engineering, its utility in power systems is limited due to the high computational effort which is incompatible with the high sampling frequency in these systems. In this paper, we propose a DSTATCOM based on Finite Control Set Model Predictive Control (FCS-MPC) with Instantaneous Symmetrical Component Theory (ISCT) based reference current extraction is proposed for load compensation and Unity Power Factor (UPF) action in current control mode. The proposed controller performance is evaluated for a 3 phase, 3 wire, 415 V, 50 Hz distribution system in MATLAB Simulink which demonstrates its applicability in real life situations.

  10. Enhancements to an Atmospheric Ascent Guidance Algorithm

    NASA Technical Reports Server (NTRS)

    Dukeman, Greg A.

    2003-01-01

    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-atmospheric flight. An alternative method for handing the transversality conditions has been developed that eliminates the need for a priori elimination of the constant multipliers that adjoin the terminal state constraints to the performance index. As a result, new constraints can be formulated and implemented with relative ease. The problem of burn-coast-burn trajectory optimization is treated using a modified multiple shooting technique.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  12. Atmospheric channel for bistatic optical communication: simulation algorithms

    NASA Astrophysics Data System (ADS)

    Belov, V. V.; Tarasenkov, M. V.

    2015-11-01

    Three algorithms of statistical simulation of the impulse response (IR) for the atmospheric optical communication channel are considered, including algorithms of local estimate and double local estimate and the algorithm suggested by us. On the example of a homogeneous molecular atmosphere it is demonstrated that algorithms of double local estimate and the suggested algorithm are more efficient than the algorithm of local estimate. For small optical path length, the proposed algorithm is more efficient, and for large optical path length, the algorithm of double local estimate is more efficient. Using the proposed algorithm, the communication quality is estimated for a particular case of the atmospheric channel under conditions of intermediate turbidity. The communication quality is characterized by the maximum IR, time of maximum IR, integral IR, and bandwidth of the communication channel. Calculations of these criteria demonstrated that communication is most efficient when the point of intersection of the directions toward the source and the receiver is most close to the source point.

  13. Multispectral filter-wheel cameras: geometric distortion model and compensation algorithms.

    PubMed

    Brauers, Johannes; Schulte, Nils; Aach, Til

    2008-12-01

    Multispectral image acquisition considerably improves color accuracy in comparison to RGB technology. A common multispectral camera design concept features a filter-wheel consisting of six or more optical bandpass filters. By shifting the filters sequentially into the optical path, the electromagnetic spectrum is acquired through the channels, thus making an approximate reconstruction of the spectrum feasible. However, since the optical filters exhibit different thicknesses, refraction indices and may not be aligned in a perfectly coplanar manner, geometric distortions occur in each spectral channel: The reconstructed RGB images thus show rainbow-like color fringes. To compensate for these, we analyze the optical path and derive a mathematical model of the distortions. Based on this model we present two different algorithms for compensation and show that the color fringes vanish completely after application of our algorithms. We also evaluate our compensation algorithms in terms of accuracy and execution time. PMID:19004709

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

    PubMed

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

    2014-10-13

    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

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

    PubMed

    Hooshmand, Rahmat Allah; Torabian Esfahani, Mahdi

    2011-04-01

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

  16. Multiple-Point Temperature Gradient Algorithm for Ring Laser Gyroscope Bias Compensation.

    PubMed

    Li, Geng; Zhang, Pengfei; Wei, Guo; Xie, Yuanping; Yu, Xudong; Long, Xingwu

    2015-01-01

    To further improve ring laser gyroscope (RLG) bias stability, a multiple-point temperature gradient algorithm is proposed for RLG bias compensation in this paper. Based on the multiple-point temperature measurement system, a complete thermo-image of the RLG block is developed. Combined with the multiple-point temperature gradients between different points of the RLG block, the particle swarm optimization algorithm is used to tune the support vector machine (SVM) parameters, and an optimized design for selecting the thermometer locations is also discussed. The experimental results validate the superiority of the introduced method and enhance the precision and generalizability in the RLG bias compensation model. PMID:26633401

  17. Multiple-Point Temperature Gradient Algorithm for Ring Laser Gyroscope Bias Compensation

    PubMed Central

    Li, Geng; Zhang, Pengfei; Wei, Guo; Xie, Yuanping; Yu, Xudong; Long, Xingwu

    2015-01-01

    To further improve ring laser gyroscope (RLG) bias stability, a multiple-point temperature gradient algorithm is proposed for RLG bias compensation in this paper. Based on the multiple-point temperature measurement system, a complete thermo-image of the RLG block is developed. Combined with the multiple-point temperature gradients between different points of the RLG block, the particle swarm optimization algorithm is used to tune the support vector machine (SVM) parameters, and an optimized design for selecting the thermometer locations is also discussed. The experimental results validate the superiority of the introduced method and enhance the precision and generalizability in the RLG bias compensation model. PMID:26633401

  18. TIGER: Development of Thermal Gradient Compensation Algorithms and Techniques

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

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

    PubMed Central

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

    2014-01-01

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

  20. A 4+1 phase shifting algorithm for rotating-compensator spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Han, Zhi-gang; Xu, Zhi; Chen, Lei

    2014-09-01

    A 4+1 phase shifting algorithm is proposed for rotating-compensator spectroscopic ellipsometry (RCSE). The spectroscopic ellipsometric parameters are determined with five spectra, taken when the compensator is rotated at the detection angles of 0°, 45°, 90°, 135°, and an additional detection angle of 22.5°. There is no need to take the dark spectrum of the spectrometer for error correction using the new method, compared to Lee's method [2] which also utilizes five spectra for RCSE. It also indicates the algorithm designed to suppress the second harmonic frequency component in traditional phase shifting algorithm is helpful to determine both fundamental and second harmonic frequency components. By taking an additional spectrum, both the two harmonic frequency components of spectra in RCSE are determined by the designed 4+1 phase shifting algorithm.

  1. Surface Composition of Mars: Results from a New Atmospheric Compensation Technique Applied to TES

    NASA Technical Reports Server (NTRS)

    Kirkland, L. E.; Herr, K. C.; Ward, J.; Keim, E. R.; Hackwell, J. H.; McAfee, J. M.

    2002-01-01

    Before TES (Thermal Emission Spectrometry) spectra can be used to model surface compositions, they must have a strong atmospheric compensation applied. We explore a very different atmospheric retrieval process, and compare results and implications for the derived surface composition. Additional information is contained in the original extended abstract.

  2. Springback Simulation and Tool Surface Compensation Algorithm for Sheet Metal Forming

    SciTech Connect

    Shen Guozhe; Hu Ping; Zhang Xiangkui; Chen Xiaobin; Li Xiaoda

    2005-08-05

    Springback is an unquenchable forming defect in the sheet metal forming process. How to calculate springback accurately is a big challenge for a lot of FEA software. Springback compensation makes the stamped final part accordant with the designed part shape by modifying tool surface, which depends on the accurate springback amount. How ever, the meshing data based on numerical simulation is expressed by nodes and elements, such data can not be supplied directly to tool surface CAD data. In this paper, a tool surface compensation algorithm based on numerical simulation technique of springback process is proposed in which the independently developed dynamic explicit springback algorithm (DESA) is used to simulate springback amount. When doing the tool surface compensation, the springback amount of the projected point can be obtained by interpolation of the springback amount of the projected element nodes. So the modified values of tool surface can be calculated reversely. After repeating the springback and compensation calculations for 1{approx}3 times, the reasonable tool surface mesh is gained. Finally, the FEM data on the compensated tool surface is fitted into the surface by CAD modeling software. The examination of a real industrial part shows the validity of the present method.

  3. Respiratory motion compensation algorithm of ultrasound hepatic perfusion data acquired in free-breathing

    NASA Astrophysics Data System (ADS)

    Wu, Kaizhi; Zhang, Xuming; Chen, Guangxie; Weng, Fei; Ding, Mingyue

    2013-10-01

    Images acquired in free breathing using contrast enhanced ultrasound exhibit a periodic motion that needs to be compensated for if a further accurate quantification of the hepatic perfusion analysis is to be executed. In this work, we present an algorithm to compensate the respiratory motion by effectively combining the PCA (Principal Component Analysis) method and block matching method. The respiratory kinetics of the ultrasound hepatic perfusion image sequences was firstly extracted using the PCA method. Then, the optimal phase of the obtained respiratory kinetics was detected after normalizing the motion amplitude and determining the image subsequences of the original image sequences. The image subsequences were registered by the block matching method using cross-correlation as the similarity. Finally, the motion-compensated contrast images can be acquired by using the position mapping and the algorithm was evaluated by comparing the TICs extracted from the original image sequences and compensated image subsequences. Quantitative comparisons demonstrated that the average fitting error estimated of ROIs (region of interest) was reduced from 10.9278 +/- 6.2756 to 5.1644 +/- 3.3431 after compensating.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  5. Comparision of algorithms for incoming atmospheric long-wave radiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While numerous algorithms exist for predicting incident atmospheric long-wave radiation under clear (Lclr) and cloudy skies, only a handful of comparisons have been published to assess the accuracy of the different algorithms. Virtually no comparisons have been made for both clear and cloudy skies ...

  6. Localization-compensation algorithm based on the Mean kShift and the Kalman filter

    NASA Astrophysics Data System (ADS)

    Lee, Dong Myung; Kim, Tae Wan; Kim, Yun-Hae

    2015-03-01

    In this paper, we propose a localization simulator based on the random walk/waypoint mobility model and a hybrid-type location-compensation algorithm using the Mean kShift/Kalman filter (MSKF) to enhance the precision of the estimated location value of mobile modules. From an analysis of our experimental results, the proposed algorithm using the MSKF can better compensate for the error rates, the average error rate per estimated distance moved by the mobile node (Err_ RateDV) and the error rate per estimated trace value of the mobile node (Err_RateTV) than the Mean shift or Kalman filter up to a maximum of 29% in a random mobility environment for the three scenarios.

  7. Retrieval of atmospheric temperature and water vapour content from thermal infrared hyperspectral data in a purpose of atmospheric compensation

    NASA Astrophysics Data System (ADS)

    Achard, V.; Lesage, S.; Poutier, L.

    2007-10-01

    Infrared hyperspectral imagery gives new opportunities for night observations for military, or security purposes, and for geological studies as rocks have specific infrared absorption bands. Generally, an optimized utilization of spectral information requires to retrieve spectral emissivity, which involves atmospheric compensation and surface temperature and emissivity separation (TES). This paper presents a new method dedicated to a future airborne hyperspectral sensor that will operate in the 3-5.5 and 8-12 µm spectral ranges, at 2.2 km height. It combines neural networks in order to characterize the required parameters for atmospheric compensation and a spectral smoothness approach for TES. The network training is performed with radiance spectra simulated with MODTRAN4, and using ASTER emissivities, and the TIGR atmospheric database. A sensitivity study based on experimental design is carried out in order to compare impacts of atmospheric and surface parameters on radiance at several wavelengths. Atmospheric compensation and TES methods are then presented and their accuracy is assessed. Sensitivity of the retrievals to instrumental characteristics such as signal to noise ratio and radiometric calibration, is also studied.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  9. An algorithm for the compensation of short-period errors in optical encoders

    NASA Astrophysics Data System (ADS)

    Mendenhall, Marcus H.; Windover, Donald; Henins, Albert; Cline, James P.

    2015-10-01

    We present a simple way to collect data from an optical position-or-angle encoder with a readout that interpolates values between the optical features, and to process these data to determine the short-range errors that arise from an interpolation process. This is commonly known as generating the compensation function for such an encoder. This process allows the user of data from an encoder to make this correction without relying on undocumented internal algorithms which may be provided by the encoder manufacturer. It can also be used to test built-in algorithms by measuring the residual error when internal algorithms are used. We apply the algorithm to a commercial angular encoder, installed in a goniometer, as an example. The determination of this function on an encoder is critical to provable angle or position metrology efforts.

  10. Heat Transport Compensation in Atmosphere and Ocean over the Past 22,000 Years

    PubMed Central

    Yang, Haijun; Zhao, Yingying; Liu, Zhengyu; Li, Qing; He, Feng; Zhang, Qiong

    2015-01-01

    The Earth’s climate has experienced dramatic changes over the past 22,000 years; however, the total meridional heat transport (MHT) of the climate system remains stable. A 22,000-year-long simulation using an ocean-atmosphere coupled model shows that the changes in atmosphere and ocean MHT are significant but tend to be out of phase in most regions, mitigating the total MHT change, which helps to maintain the stability of the Earth’s overall climate. A simple conceptual model is used to understand the compensation mechanism. The simple model can reproduce qualitatively the evolution and compensation features of the MHT over the past 22,000 years. We find that the global energy conservation requires the compensation changes in the atmosphere and ocean heat transports. The degree of compensation is mainly determined by the local climate feedback between surface temperature and net radiation flux at the top of the atmosphere. This study suggests that an internal mechanism may exist in the climate system, which might have played a role in constraining the global climate change over the past 22,000 years. PMID:26567710

  11. Heat Transport Compensation in Atmosphere and Ocean over the Past 22,000 Years.

    PubMed

    Yang, Haijun; Zhao, Yingying; Liu, Zhengyu; Li, Qing; He, Feng; Zhang, Qiong

    2015-01-01

    The Earth's climate has experienced dramatic changes over the past 22,000 years; however, the total meridional heat transport (MHT) of the climate system remains stable. A 22,000-year-long simulation using an ocean-atmosphere coupled model shows that the changes in atmosphere and ocean MHT are significant but tend to be out of phase in most regions, mitigating the total MHT change, which helps to maintain the stability of the Earth's overall climate. A simple conceptual model is used to understand the compensation mechanism. The simple model can reproduce qualitatively the evolution and compensation features of the MHT over the past 22,000 years. We find that the global energy conservation requires the compensation changes in the atmosphere and ocean heat transports. The degree of compensation is mainly determined by the local climate feedback between surface temperature and net radiation flux at the top of the atmosphere. This study suggests that an internal mechanism may exist in the climate system, which might have played a role in constraining the global climate change over the past 22,000 years. PMID:26567710

  12. Heat Transport Compensation in Atmosphere and Ocean over the Past 22,000 Years

    NASA Astrophysics Data System (ADS)

    Yang, Haijun; Zhao, Yingying; Liu, Zhengyu; Li, Qing; He, Feng; Zhang, Qiong

    2015-11-01

    The Earth’s climate has experienced dramatic changes over the past 22,000 years; however, the total meridional heat transport (MHT) of the climate system remains stable. A 22,000-year-long simulation using an ocean-atmosphere coupled model shows that the changes in atmosphere and ocean MHT are significant but tend to be out of phase in most regions, mitigating the total MHT change, which helps to maintain the stability of the Earth’s overall climate. A simple conceptual model is used to understand the compensation mechanism. The simple model can reproduce qualitatively the evolution and compensation features of the MHT over the past 22,000 years. We find that the global energy conservation requires the compensation changes in the atmosphere and ocean heat transports. The degree of compensation is mainly determined by the local climate feedback between surface temperature and net radiation flux at the top of the atmosphere. This study suggests that an internal mechanism may exist in the climate system, which might have played a role in constraining the global climate change over the past 22,000 years.

  13. Spatial reduction algorithm for atmospheric chemical transport models

    PubMed Central

    Rastigejev, Y.; Brenner, M. P.; Jacob, D. J.

    2007-01-01

    Numerical modeling of global atmospheric chemical dynamics presents an enormous challenge, associated with simulating hundreds of chemical species with time scales varying from milliseconds to years. Here we present an algorithm that provides a significant reduction in computational cost. Because most of the fast reactants and their quickly decomposing reaction products are localized near emission sources, we use a series of reduced chemical models of decreasing complexity with increasing distance from the source. The algorithm diagnoses the chemical dynamics on-the-run, locally and separately for every species according to its characteristic reaction time. Unlike conventional time-scale separation methods, the spatial reduction algorithm speeds up not only the chemical solver but also advectiondiffusion integration. Through several examples we demonstrate that the algorithm can reduce computational cost by at least an order of magnitude for typical atmospheric chemical kinetic mechanisms. PMID:17715302

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

    PubMed

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

    2010-01-01

    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. PMID:20799807

  15. Infrared micro-scanning error compensation algorithm based on edge location

    NASA Astrophysics Data System (ADS)

    Gao, Hang; Chen, Qian; Sui, Xiubao

    2015-03-01

    For area-array thermal imaging devices, an essential factor affecting the system imaging quality is the sub-sampling caused by oversized discrete sampling pitch. In order to obtain higher spatial resolution, staring infrared focal plane array (IRFPA) gets multi-frame sub-sampling images by micro-scanning movement to achieve an adequate spatial sampling frequency. However, influenced by external environment and the accuracy of the scanning system itself, the relative displacement between the detector and the scene cannot be absolutely precisely controlled, but exist some error, which will affect the final performance of the reconstructed high-resolution image. We analyzed the distribution of the error and then proposed an infrared micro-scanning error compensation algorithm based on edge location, which is inspired by human retina fixational eye movement pattern. It first locates the edge point in the reconstruction unit and finds the corresponding characteristic values. Later on, matches the characteristic value with the fixed templates and reorders the pixel responses in reconstruction unit utilizing the gray correlation. Finally, it compensates the error real-timely through repeated update and iteration. We apply the algorithm in video sequences acquired by 4-step infrared micro-scanning system. The experiment results show that when aligning to a static scene or stationary region in dynamic scene, the algorithm possesses good resolution enhancement effect, particularly, can improve the clarity and the accuracy of static image edge details.

  16. Doppler-based motion compensation algorithm for focusing the signature of a rotorcraft.

    PubMed

    Goldman, Geoffrey H

    2013-02-01

    A computationally efficient algorithm was developed and tested to compensate for the effects of motion on the acoustic signature of a rotorcraft. For target signatures with large spectral peaks that vary slowly in amplitude and have near constant frequency, the time-varying Doppler shift can be tracked and then removed from the data. The algorithm can be used to preprocess data for classification, tracking, and nulling algorithms. The algorithm was tested on rotorcraft data. The average instantaneous frequency of the first harmonic of a rotorcraft was tracked with a fixed-lag smoother. Then, state space estimates of the frequency were used to calculate a time warping that removed the effect of a time-varying Doppler shift from the data. The algorithm was evaluated by analyzing the increase in the amplitude of the harmonics in the spectrum of a rotorcraft. The results depended upon the frequency of the harmonics and the processing interval duration. Under good conditions, the results for the fundamental frequency of the target (~11 Hz) almost achieved an estimated upper bound. The results for higher frequency harmonics had larger increases in the amplitude of the peaks, but significantly lower than the estimated upper bounds. PMID:23363088

  17. Algorithm for Atmospheric Corrections of Aircraft and Satellite Imagery

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  18. Algorithm for atmospheric corrections of aircraft and satellite imagery

    NASA Technical Reports Server (NTRS)

    Fraser, R. S.; Ferrare, R. A.; Kaufman, Y. J.; Markham, B. L.; Mattoo, S.

    1992-01-01

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

  19. Deep Pacific CaCO 3 compensation and glacial-interglacial atmospheric CO 2

    NASA Astrophysics Data System (ADS)

    Marchitto, Thomas M.; Lynch-Stieglitz, Jean; Hemming, Sidney R.

    2005-03-01

    Benthic foraminiferal ?13C suggests that there was a net shift of isotopically light metabolic CO 2 from the upper ocean into the deep ocean during the last glacial period. According to the 'CaCO 3 compensation' hypothesis, this should have caused a transient drop in deep ocean CO 32- that was eventually reversed by seafloor dissolution of CaCO 3. The resulting increase in whole-ocean pH may have had a significant impact on atmospheric CO 2, compounding any decrease that was due to the initial vertical CO 2 shift. The opposite hypothetically occurred during deglaciation, when CO 2 was returned to the upper ocean (and atmosphere) and deep ocean CO 32- temporarily increased, followed by excess burial of CaCO 3 and a drop in whole-ocean pH. The deep sea record of CaCO 3 preservation appears to reflect these processes, with the largest excursion during deglaciation (as expected), but various factors make quantification of deep sea paleo-CO 32- difficult. Here we reconstruct deep equatorial Pacific CO 32- over the last glacial-interglacial cycle using benthic foraminiferal Zn/Ca, which is strongly affected by saturation state during calcite precipitation. Our data are in agreement with the CaCO 3 compensation theory, including glacial CO 32- concentrations similar to (or slightly lower than) today, and a Termination I CO 32- peak of 25-30 ?mol kg -1. The deglacial CO 32- rise precedes ice sheet melting, consistent with the timing of the atmospheric CO 2 rise. A later portion of the peak could reflect removal of CO 2 from the atmosphere-ocean system due to boreal forest regrowth. CaCO 3 compensation alone may explain more than one third of the atmospheric CO 2 lowering during glacial times.

  20. Atmospheric turbulence and sensor system effects on biometric algorithm performance

    NASA Astrophysics Data System (ADS)

    Espinola, Richard L.; Leonard, Kevin R.; Byrd, Kenneth A.; Potvin, Guy

    2015-05-01

    Biometric technologies composed of electro-optical/infrared (EO/IR) sensor systems and advanced matching algorithms are being used in various force protection/security and tactical surveillance applications. To date, most of these sensor systems have been widely used in controlled conditions with varying success (e.g., short range, uniform illumination, cooperative subjects). However the limiting conditions of such systems have yet to be fully studied for long range applications and degraded imaging environments. Biometric technologies used for long range applications will invariably suffer from the effects of atmospheric turbulence degradation. Atmospheric turbulence causes blur, distortion and intensity fluctuations that can severely degrade image quality of electro-optic and thermal imaging systems and, for the case of biometrics technology, translate to poor matching algorithm performance. In this paper, we evaluate the effects of atmospheric turbulence and sensor resolution on biometric matching algorithm performance. We use a subset of the Facial Recognition Technology (FERET) database and a commercial algorithm to analyze facial recognition performance on turbulence degraded facial images. The goal of this work is to understand the feasibility of long-range facial recognition in degraded imaging conditions, and the utility of camera parameter trade studies to enable the design of the next generation biometrics sensor systems.

  1. Initial validation of atmospheric compensation for a Landsat land surface temperature product

    NASA Astrophysics Data System (ADS)

    Cook, Monica J.; Schott, John R.

    2013-05-01

    The Landsat series of satellites is the longest set of continuously acquired moderate resolution multispectral satellite imagery collected on a single maintained family of instruments. The data are very attractive because the entire archive has been radiometrically calibrated and characterized so that sensor reaching radiance values are well known. Because of the spatial and temporal coverage provided by Landsat, it is an intriguing candidate for a land surface temperature (LST) product, an important earth system data record for a number of fields including numerical weather prediction, climate research and a number of agricultural applications. Using the Landsat long-wave infrared thermal band, LST can be derived with a well-characterized atmosphere and a known surface emissivity. This work integrates the North America Regional Reanalysis dataset (atmospheric profile data) with ASTER derived emissivity data to perform LST retrievals. This paper emphasizes progress toward atmospheric compensation at each Landsat pixel. Due to differences in temporal and spatial sampling, a number of interpolations are required to compute the radiance due to temperature at each pixel. Radiosonde data and water temperatures derived from buoys are used as ground truth data to explore the error in the final predicted temperature. Preliminary results show consistent errors of less than 1 K in clear atmospheres but higher errors in hotter and more humid atmospheres. Future work will analyze results to predict error in the final retrieved temperatures using atmospheric conditions. The final goal is to report both a predicted LST and a confidence in this value.

  2. Finite element-wavelet hybrid algorithm for atmospheric tomography.

    PubMed

    Yudytskiy, Mykhaylo; Helin, Tapio; Ramlau, Ronny

    2014-03-01

    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

  3. Control algorithms for aerobraking in the Martian atmosphere

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Nerheim, N.

    1989-01-01

    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.

  5. Application of the parallel generalized projection algorithm to the control of two finite-resolution deformable mirrors for scintillation compensation.

    PubMed

    Barchers, Jeffrey D

    2002-01-01

    A modification of the parallel generalized projection algorithm is presented that allows for the use of projections in a weighted norm. Convergence properties of the modified algorithm, denoted the weighted parallel generalized projection algorithm, are developed. The weighted parallel generalized projection algorithm is applied to the control of two finite-resolution deformable mirrors to compensate for both the amplitude and the phase fluctuations that result from propagation through a turbulent medium. Numerical results are shown that indicate that a two-deformable-mirror system can provide improved performance over that of a single-deformable-mirror system. PMID:11778733

  6. Mars Entry Atmospheric Data System Modelling and Algorithm Development

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    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.

  7. A compact algorithm for three-phase three-wire system reactive power compensation and load balancing

    SciTech Connect

    Lee, S.Y.; Chang, W.N.; Wu, C.J.

    1995-12-31

    A compact control algorithm for reactive power compensation and load balancing with the static var compensator (SVC) in three-phase three-wire systems is developed in this paper. Each phase susceptance of the SVC can be obtained from a very simple function of voltage and power signals which are measured by a three-phase voltage transducer and two single-phase active and reactive power (P-Q) transducers at the load bus. The calculation of compensation susceptances is based on the criterion of a unity power factor and zero sequence currents after compensation. A simulation is made, as the first stage, to show the validity of the proposed compensation algorithm. Then, a laboratory size microcomputer-based SVC, which consists of thyristor-controlled reactors (TCRs) and fixed capacitors (FCs), is designed and implemented. Simulation and experiment results show that the algorithm is very suitable for on-line control of the SVC which is designed for phase balancing and power factor correction.

  8. Aerosol Retrieval and Atmospheric Correction Algorithms for EPIC

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Lyapustin, A.; Marshak, A.; Korkin, S.; Herman, J. R.

    2011-12-01

    EPIC is a multi-spectral imager onboard planned Deep Space Climate ObserVatoRy (DSCOVR) designed for observations of the full illuminated disk of the Earth with high temporal and coarse spatial resolution (10 km) from Lagrangian L1 point. During the course of the day, EPIC will view the same Earth surface area in the full range of solar and view zenith angles at equator with fixed scattering angle near the backscattering direction. This talk will describe a new aerosol retrieval/atmospheric correction algorithm developed for EPIC and tested with EPIC Simulator data. This algorithm uses the time series approach and consists of two stages: the first stage is designed to periodically re-initialize the surface spectral bidirectional reflectance (BRF) on stable low AOD days. Such days can be selected based on the same measured reflectance between the morning and afternoon reciprocal view geometries of EPIC. On the second stage, the algorithm will monitor the diurnal cycle of aerosol optical depth and fine mode fraction based on the known spectral surface BRF. Testing of the developed algorithm with simulated EPIC data over continental USA showed a good accuracy of AOD retrievals (10-20%) except over very bright surfaces.

  9. Aerosol Retrieval and Atmospheric Correction Algorithms for EPIC

    NASA Technical Reports Server (NTRS)

    Wang, Yujie; Lyapustin, Alexei; Marshak, Alexander; Korkin, Sergey; Herman, Jay

    2011-01-01

    EPIC is a multi-spectral imager onboard planned Deep Space Climate ObserVatoRy (DSCOVR) designed for observations of the full illuminated disk of the Earth with high temporal and coarse spatial resolution (10 km) from Lagrangian L1 point. During the course of the day, EPIC will view the same Earth surface area in the full range of solar and view zenith angles at equator with fixed scattering angle near the backscattering direction. This talk will describe a new aerosol retrieval/atmospheric correction algorithm developed for EPIC and tested with EPIC Simulator data. This algorithm uses the time series approach and consists of two stages: the first stage is designed to periodically re-initialize the surface spectral bidirectional reflectance (BRF) on stable low AOD days. Such days can be selected based on the same measured reflectance between the morning and afternoon reciprocal view geometries of EPIC. On the second stage, the algorithm will monitor the diurnal cycle of aerosol optical depth and fine mode fraction based on the known spectral surface BRF. Testing of the developed algorithm with simulated EPIC data over continental USA showed a good accuracy of AOD retrievals (10-20%) except over very bright surfaces.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    PubMed Central

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

    2008-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Jacques, Robert; McNutt, Todd

    2014-03-01

    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.

  13. Algorithmic vs. finite difference Jacobians for infrared atmospheric radiative transfer

    NASA Astrophysics Data System (ADS)

    Schreier, Franz; Gimeno García, Sebastián; Vasquez, Mayte; Xu, Jian

    2015-10-01

    Jacobians, i.e. partial derivatives of the radiance and transmission spectrum with respect to the atmospheric state parameters to be retrieved from remote sensing observations, are important for the iterative solution of the nonlinear inverse problem. Finite difference Jacobians are easy to implement, but computationally expensive and possibly of dubious quality; on the other hand, analytical Jacobians are accurate and efficient, but the implementation can be quite demanding. GARLIC, our "Generic Atmospheric Radiation Line-by-line Infrared Code", utilizes algorithmic differentiation (AD) techniques to implement derivatives w.r.t. atmospheric temperature and molecular concentrations. In this paper, we describe our approach for differentiation of the high resolution infrared and microwave spectra and provide an in-depth assessment of finite difference approximations using "exact" AD Jacobians as a reference. The results indicate that the "standard" two-point finite differences with 1 K and 1% perturbation for temperature and volume mixing ratio, respectively, can exhibit substantial errors, and central differences are significantly better. However, these deviations do not transfer into the truncated singular value decomposition solution of a least squares problem. Nevertheless, AD Jacobians are clearly recommended because of the superior speed and accuracy.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  15. Influence of measuring algorithm on shape accuracy in the compensating turning of high gradient thin-wall parts

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Wang, Guilin; Zhu, Dengchao; Li, Shengyi

    2015-02-01

    In order to meet the requirement of aerodynamics, the infrared domes or windows with conformal and thin-wall structure becomes the development trend of high-speed aircrafts in the future. But these parts usually have low stiffness, the cutting force will change along with the axial position, and it is very difficult to meet the requirement of shape accuracy by single machining. Therefore, on-machine measurement and compensating turning are used to control the shape errors caused by the fluctuation of cutting force and the change of stiffness. In this paper, on the basis of ultra precision diamond lathe, a contact measuring system with five DOFs is developed to achieve on-machine measurement of conformal thin-wall parts with high accuracy. According to high gradient surface, the optimizing algorithm is designed on the distribution of measuring points by using the data screening method. The influence rule of sampling frequency is analyzed on measuring errors, the best sampling frequency is found out based on planning algorithm, the effect of environmental factors and the fitting errors are controlled within lower range, and the measuring accuracy of conformal dome is greatly improved in the process of on-machine measurement. According to MgF2 conformal dome with high gradient, the compensating turning is implemented by using the designed on-machine measuring algorithm. The shape error is less than PV 0.8?m, greatly superior compared with PV 3?m before compensating turning, which verifies the correctness of measuring algorithm.

  16. The application of atmospheric correction algorithms for monitoring atmospheric pollution using Landsat TM images

    NASA Astrophysics Data System (ADS)

    Hadjimitsis, Diofantos G.; Themistokleous, Kyriacos P.; Papadavid, Giorgos

    2008-10-01

    This paper focused on the application of effective atmospheric correction algorithm for assessing the atmospheric pollution based on the determined aerosol optical thickness. Field spectro-radiometers such as GER 1500 and HR-1024 have been used to retrieve the ground reflectance values of certain proposed calibration targets. Sun-photometers (MICROTOPS II) have been used to measure the aerosol optical thickness. Retrieved aerosol optical thickness from satellite images have been directly compared with the values found from the sun-photometer measurements as well those found from the visibility data obtained during the satellite overpass. The determined aerosol optical thickness obtained from the atmospheric path radiance component and those found from ground measurements (sun-photometer and meteorological data) acquired during the satellite overpass show very high correlations after regression analysis application.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  18. Elevated atmospheric CO2 decreases the ammonia compensation point of barley plants

    PubMed Central

    Wang, Liang; Pedas, Pai; Eriksson, Dennis; Schjoerring, Jan K.

    2013-01-01

    The ammonia compensation point () controls the direction and magnitude of NH3 exchange between plant leaves and the atmosphere. Very limited information is currently available on how responds to anticipated climate changes. Young barley plants were grown for 2 weeks at ambient (400 μmol mol–1) or elevated (800 μmol mol–1) CO2 concentration with or NH4NO3 as the nitrogen source. The concentrations of and H+ in the leaf apoplastic solution were measured along with different foliar N pools and enzymes involved in N metabolism. Elevated CO2 caused a threefold decrease in the concentration in the apoplastic solution and slightly acidified it. This resulted in a decline of the from 2.25 and 2.95 nmol mol–1 under ambient CO2 to 0.37 and 0.89 nmol mol–1 at elevated CO2 in the and NH4NO3 treatments, respectively. The decrease in at elevated CO2 reflected a lower N concentration (–25%) in the shoot dry matter. The activity of nitrate reductase also declined (–45 to –60%), while that of glutamine synthetase was unaffected by elevated CO2. It is concluded that elevated CO2 increases the likelihood of plants being a sink for atmospheric NH3 and reduces episodes of NH3 emission from plants. PMID:23740933

  19. Models and algorithms for vision through the atmosphere

    NASA Astrophysics Data System (ADS)

    Narasimhan, Srinivasa G.

    2004-11-01

    Current vision systems are designed to perform in clear weather. Needless to say, in any outdoor application, there is no escape from bad weather. Ultimately, computer vision systems must include mechanisms that enable them to function (even if somewhat less reliably) in the presence of haze, fog, rain, hail and snow. We begin by studying the visual manifestations of different weather conditions. For this, we draw on what is already known about atmospheric optics, and identify effects caused by bad weather that can be turned to our advantage; we are not only interested in what bad weather does to vision but also what it can do for vision. This thesis presents a novel and comprehensive set of models, algorithms and image datasets for better image understanding in bad weather. The models presented here can be broadly classified into single scattering and multiple scattering models. Existing single scattering models like attenuation and airlight form the basis of three new models viz., the contrast model, the dichromatic model and the polarization model. Each of these models is suited to different types of atmospheric and illumination conditions as well as different sensor types. Based on these models, we develop algorithms to recover pertinent scene properties, such as 3D structure, and clear day scene contrasts and colors, from one or more images taken under poor weather conditions. Next, we present an analytic model for multiple scattering of light in a scattering medium. From a single image of a light source immersed in a medium, interesting properties of the medium can be estimated. If the medium is the atmosphere, the weather condition and the visibility of the atmosphere can be estimated. These quantities can in turn be used to remove the glows around sources obtaining a clear picture of the scene. Based on these results, the camera serves as a "visual weather meter". Our analytic model can be used to analyze scattering in virtually any scattering medium, including fluids and tissues. Therefore, in addition to vision in bad weather, our work has implications for real-time rendering of participating media in computer graphics, medical imaging and underwater imaging. Apart from the models and algorithms, we have acquired an extensive database of images of an outdoor scene almost every hour for 9 months. This dataset is the first of its kind and includes high quality calibrated images captured under a wide variety of weather and illumination conditions and all four seasons. Such a dataset could not only be used as a testbed for validating existing appearance models (including the ones presented in this work) but also inspire new data driven models. In addition to computer vision, this dataset could be useful for researchers in other fields like graphics, image processing, remote sensing and atmospheric sciences. The database is freely distributed for research purposes and can be requested through our web site http://www.cs.columbia.edu/wild. We believe that this thesis opens new research directions needed for computer vision to be successful in the outdoors.

  20. An Algorithm to Atmospherically Correct Visible and Thermal Airborne Imagery

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    The program Watts implements a system of physically based models developed by the authors, described elsewhere, for the removal of atmospheric effects in multispectral imagery. The band range we treat covers the visible, near IR and the thermal IR. Input to the program begins with atmospheric pal red models specifying transmittance and path radiance. The system also requires the sensor's spectral response curves and knowledge of the scanner's geometric definition. Radiometric characterization of the sensor during data acquisition is also necessary. While the authors contend that active calibration is critical for serious analytical efforts, we recognize that most remote sensing systems, either airborne or space borne, do not as yet attain that minimal level of sophistication. Therefore, Watts will also use semi-active calibration where necessary and available. All of the input is then reduced to common terms, in terms of the physical units. From this it Is then practical to convert raw sensor readings into geophysically meaningful units. There are a large number of intricate details necessary to bring an algorithm or this type to fruition and to even use the program. Further, at this stage of development the authors are uncertain as to the optimal presentation or minimal analytical techniques which users of this type of software must have. Therefore, Watts permits users to break out and analyze the input in various ways. Implemented in REXX under OS/2 the program is designed with attention to the probability that it will be ported to other systems and other languages. Further, as it is in REXX, it is relatively simple for anyone that is literate in any computer language to open the code and modify to meet their needs. The authors have employed Watts in their research addressing precision agriculture and urban heat island.

  1. An adaptive compensation algorithm for temperature drift of micro-electro-mechanical systems gyroscopes using a strong tracking Kalman filter.

    PubMed

    Feng, Yibo; Li, Xisheng; Zhang, Xiaojuan

    2015-01-01

    We present an adaptive algorithm for a system integrated with micro-electro-mechanical systems (MEMS) gyroscopes and a compass to eliminate the influence from the environment, compensate the temperature drift precisely, and improve the accuracy of the MEMS gyroscope. We use a simplified drift model and changing but appropriate model parameters to implement this algorithm. The model of MEMS gyroscope temperature drift is constructed mostly on the basis of the temperature sensitivity of the gyroscope. As the state variables of a strong tracking Kalman filter (STKF), the parameters of the temperature drift model can be calculated to adapt to the environment under the support of the compass. These parameters change intelligently with the environment to maintain the precision of the MEMS gyroscope in the changing temperature. The heading error is less than 0.6° in the static temperature experiment, and also is kept in the range from 5° to -2° in the dynamic outdoor experiment. This demonstrates that the proposed algorithm exhibits strong adaptability to a changing temperature, and performs significantly better than KF and MLR to compensate the temperature drift of a gyroscope and eliminate the influence of temperature variation. PMID:25985165

  2. An Adaptive Compensation Algorithm for Temperature Drift of Micro-Electro-Mechanical Systems Gyroscopes Using a Strong Tracking Kalman Filter

    PubMed Central

    Feng, Yibo; Li, Xisheng; Zhang, Xiaojuan

    2015-01-01

    We present an adaptive algorithm for a system integrated with micro-electro-mechanical systems (MEMS) gyroscopes and a compass to eliminate the influence from the environment, compensate the temperature drift precisely, and improve the accuracy of the MEMS gyroscope. We use a simplified drift model and changing but appropriate model parameters to implement this algorithm. The model of MEMS gyroscope temperature drift is constructed mostly on the basis of the temperature sensitivity of the gyroscope. As the state variables of a strong tracking Kalman filter (STKF), the parameters of the temperature drift model can be calculated to adapt to the environment under the support of the compass. These parameters change intelligently with the environment to maintain the precision of the MEMS gyroscope in the changing temperature. The heading error is less than 0.6° in the static temperature experiment, and also is kept in the range from 5° to −2° in the dynamic outdoor experiment. This demonstrates that the proposed algorithm exhibits strong adaptability to a changing temperature, and performs significantly better than KF and MLR to compensate the temperature drift of a gyroscope and eliminate the influence of temperature variation. PMID:25985165

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

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

    2014-01-01

    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

  5. Design of Jitter Compensation Algorithm for Robot Vision Based on Optical Flow and Kalman Filter

    PubMed Central

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

    2014-01-01

    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

  6. Design of error-compensating algorithms for sinusoidal phase shifting interferometry

    SciTech Connect

    Groot, Peter de

    2009-12-10

    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.

  7. The Use of Anatomical Information for Molecular Image Reconstruction Algorithms: Attenuation/Scatter Correction, Motion Compensation, and Noise Reduction.

    PubMed

    Chun, Se Young

    2016-03-01

    PET and SPECT are important tools for providing valuable molecular information about patients to clinicians. Advances in nuclear medicine hardware technologies and statistical image reconstruction algorithms enabled significantly improved image quality. Sequentially or simultaneously acquired anatomical images such as CT and MRI from hybrid scanners are also important ingredients for improving the image quality of PET or SPECT further. High-quality anatomical information has been used and investigated for attenuation and scatter corrections, motion compensation, and noise reduction via post-reconstruction filtering and regularization in inverse problems. In this article, we will review works using anatomical information for molecular image reconstruction algorithms for better image quality by describing mathematical models, discussing sources of anatomical information for different cases, and showing some examples. PMID:26941855

  8. SAR motion through resolution cell compensation and feature extraction by a RELAX-based algorithm

    NASA Astrophysics Data System (ADS)

    Sun, Changyin; Bao, Zheng

    1999-08-01

    In this paper, we establish a data model for the feature extraction of point scatterers in the presence of motion through resolution cell (MTRC) errors and unknown noise, the data model is a sum of 2-dimensional sinusoidal signals with quadratic phase errors, which are caused by 'range walk' and 'variable range rate' respectively. Based on the data model, we propose a parametric RELAX-based algorithm to extract the target features when there are MTRC errors in radar imaging. The algorithm minimizes a complicated nonlinear least-squares (NLS) cost function, and it is performed alternately by letting only the parameters and errors of one scatterer vary and freezing all others at their most recently determined values. The Cramer-Rao bounds (CRB's) for the parameters of the data model are also derived. We compare the performance of the proposed algorithm with the CRB's by simulation. And the results show that the mean squared errors of the parameter estimates obtained by the algorithm can approach the corresponding CRB's. Then we apply the algorithm to the simulated radar data with MTRC errors. The proposed algorithm generates 'focused' point image with higher resolution, which conforms the algorithm and the data model.

  9. Rain detection and removal algorithm using motion-compensated non-local mean filter

    NASA Astrophysics Data System (ADS)

    Song, B. C.; Seo, S. J.

    2015-03-01

    This paper proposed a novel rain detection and removal algorithm robust against camera motions. It is very difficult to detect and remove rain in video with camera motion. So, most previous works assume that camera is fixed. However, these methods are not useful for application. The proposed algorithm initially detects possible rain streaks by using spatial properties such as luminance and structure of rain streaks. Then, the rain streak candidates are selected based on Gaussian distribution model. Next, a non-rain block matching algorithm is performed between adjacent frames to find similar blocks to each including rain pixels. If the similar blocks to the block are obtained, the rain region of the block is reconstructed by non-local mean (NLM) filtering using the similar neighbors. Experimental results show that the proposed method outperforms previous works in terms of objective and subjective visual quality.

  10. Coupled Inertial Navigation and Flush Air Data Sensing Algorithm for Atmosphere Estimation

    NASA Technical Reports Server (NTRS)

    Karlgaard, Christopher D.; Kutty, Prasad; Schoenenberger, Mark

    2015-01-01

    This paper describes an algorithm for atmospheric state estimation that is based on a coupling between inertial navigation and flush air data sensing pressure measurements. In this approach, the full navigation state is used in the atmospheric estimation algorithm along with the pressure measurements and a model of the surface pressure distribution to directly estimate atmospheric winds and density using a nonlinear weighted least-squares algorithm. The approach uses a high fidelity model of atmosphere stored in table-look-up form, along with simplified models of that are propagated along the trajectory within the algorithm to provide prior estimates and covariances to aid the air data state solution. Thus, the method is essentially a reduced-order Kalman filter in which the inertial states are taken from the navigation solution and atmospheric states are estimated in the filter. The algorithm is applied to data from the Mars Science Laboratory entry, descent, and landing from August 2012. Reasonable estimates of the atmosphere and winds are produced by the algorithm. The observability of winds along the trajectory are examined using an index based on the discrete-time observability Gramian and the pressure measurement sensitivity matrix. The results indicate that bank reversals are responsible for adding information content to the system. The algorithm is then applied to the design of the pressure measurement system for the Mars 2020 mission. The pressure port layout is optimized to maximize the observability of atmospheric states along the trajectory. Linear covariance analysis is performed to assess estimator performance for a given pressure measurement uncertainty. The results indicate that the new tightly-coupled estimator can produce enhanced estimates of atmospheric states when compared with existing algorithms.

  11. Segmented frequency offset compensation algorithm in coherent optical sub-sampling system

    NASA Astrophysics Data System (ADS)

    Tan, Qingzhao; Yang, Aiying; Zhao, Weirui; Feng, Lihui

    2015-08-01

    An inter-partitioned FFT algorithm is proposed to estimate the difference between the frequency of local optical sampling pulse and the signal to be sampled in coherent optical sampling system. By dividing the sampled data into several parts, the frequency difference of each part is estimated using FFT, respectively. The experiment demonstrated that, with the inter-partitioned FFT algorithm, the measured Q factor of 32GB QPSK signal is improved by 6dB, and matched the results obtained by the commercially available optical signal analyzer (EXFO PSO-200).

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

    NASA Astrophysics Data System (ADS)

    Frolov, Vladimir; Backhaus, Scott; Chertkov, Misha

    2014-10-01

    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.

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

    SciTech Connect

    Frolov, Vladimir; Backhaus, Scott; Chertkov, Misha

    2014-10-01

    In a companion manuscript, we developed a novel optimization method for 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 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 on the 30-bus network are used to study the general properties of the solutions including non-locality and sparsity. The Polish grid is used as a demonstration of the computational efficiency of the heuristics that leverages 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, the algorithm is able to solve an instance of Polish grid in tens of seconds. We explore the utility of the algorithm by analyzing transmission networks congested by (a) uniform load growth, (b) multiple overloaded configurations, and (c) sequential generator retirements.

  14. Efficient Algorithm for Locating and Sizing Series Compensation Devices in Large Transmission Grids: Solutions and Applications (PART II)

    SciTech Connect

    Frolov, Vladimir; Backhaus, Scott N.; Chertkov, Michael

    2014-01-14

    In a companion manuscript, we developed a novel optimization method for 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 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 on the 30-bus network are used to study the general properties of the solutions including non-locality and sparsity. The Polish grid is used as a demonstration of the computational efficiency of the heuristics that leverages 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, the algorithm is able to solve an instance of Polish grid in tens of seconds. We explore the utility of the algorithm by analyzing transmission networks congested by (a) uniform load growth, (b) multiple overloaded configurations, and (c) sequential generator retirements

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

    DOE PAGESBeta

    Frolov, Vladimir; Backhaus, Scott; Chertkov, Misha

    2014-10-01

    In a companion manuscript, we developed a novel optimization method for 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 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 on the 30-bus network are used to study the general properties of the solutions including non-locality and sparsity. The Polishmore » grid is used as a demonstration of the computational efficiency of the heuristics that leverages 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, the algorithm is able to solve an instance of Polish grid in tens of seconds. We explore the utility of the algorithm by analyzing transmission networks congested by (a) uniform load growth, (b) multiple overloaded configurations, and (c) sequential generator retirements.« less

  16. An Adaptive Spectral Compensation Algorithm for Avoiding Flexural Vibration of Printing Cylinders

    NASA Astrophysics Data System (ADS)

    Hermanski, M.; Kohn, K.-U.; Ostholt, H.

    1995-10-01

    Flexo printing is a modern technique for multi-colour printing of foil and paper. During the printing process the colour is transmitted from the cliché mounted on a rotating cylinder to the passing foil. It has been known for a long time that under operating conditions stripes of variable intensity occur perpendicular to the direction of printing. In this paper the sources of vibration which cause such stripes are described. These vibrations are quasi-stationary, and non-harmonic and vary with different operation conditions. Techniques for compensating the vibration of the cylinders, in particular with active actuators, were investigated at the Laboratory of Sound and Structural Analysis at the Fachhochschule Bielefeld. The present paper surveys this project.

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

    PubMed

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

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    PubMed

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

    2014-02-01

    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

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

    SciTech Connect

    Frolov, Vladimir; Backhaus, Scott; Chertkov, Misha

    2014-10-24

    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) which 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 up 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.

  1. Efficient Algorithm for Locating and Sizing Series Compensation Devices in Large Transmission Grids: Model Implementation (PART 1)

    SciTech Connect

    Frolov, Vladimir; Backhaus, Scott N.; Chertkov, Michael

    2014-01-14

    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) which 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 up 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.

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

    NASA Astrophysics Data System (ADS)

    Frolov, Vladimir; Backhaus, Scott; Chertkov, Misha

    2014-10-01

    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.

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

    DOE PAGESBeta

    Frolov, Vladimir; Backhaus, Scott; Chertkov, Misha

    2014-10-24

    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) which are accelerated further using cutting plane methods. The algorithm solves an instance of the MatPower Polishmore » Grid model (3299 lines and 2746 nodes) in 40 seconds per iteration on a standard laptop—a speed up 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.« less

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

    DOEpatents

    Veligdan, James T. (Manorville, NY)

    1993-01-01

    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.

  5. Analysis and compensation of the effects of analog VLSI arithmetic on the LMS algorithm.

    PubMed

    Carvajal, Gonzalo; Figueroa, Miguel; Sbarbaro, Daniel; Valenzuela, Waldo

    2011-07-01

    Analog very large scale integration implementations of neural networks can compute using a fraction of the size and power required by their digital counterparts. However, intrinsic limitations of analog hardware, such as device mismatch, charge leakage, and noise, reduce the accuracy of analog arithmetic circuits, degrading the performance of large-scale adaptive systems. In this paper, we present a detailed mathematical analysis that relates different parameters of the hardware limitations to specific effects on the convergence properties of linear perceptrons trained with the least-mean-square (LMS) algorithm. Using this analysis, we derive design guidelines and introduce simple on-chip calibration techniques to improve the accuracy of analog neural networks with a small cost in die area and power dissipation. We validate our analysis by evaluating the performance of a mixed-signal complementary metal-oxide-semiconductor implementation of a 32-input perceptron trained with LMS. PMID:21622073

  6. CEMERLL: The Propagation of an Atmosphere-Compensated Laser Beam to the Apollo 15 Lunar Array

    NASA Technical Reports Server (NTRS)

    Fugate, R. Q.; Leatherman, P. R.; Wilson, K. E.

    1997-01-01

    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.

  7. A preliminary assessment of the Nimbus-7 CZCS atmospheric correction algorithm in a horizontally inhomogeneous atmosphere. [Coastal Zone Color Scanner

    NASA Technical Reports Server (NTRS)

    Gordon, H. R.

    1981-01-01

    For an estimation of the concentration of phytoplankton pigments in the oceans on the basis of Nimbus-7 CZCS imagery, it is necessary to remove the effects of the intervening atmosphere from the satellite imagery. The principle effect of the atmosphere is a loss in contrast caused by the addition of a substantial amount of radiance (path radiance) to that scatttered out of the water. Gordon (1978) has developed a technique which shows considerable promise for removal of these atmospheric effects. Attention is given to the correction algorithm, and its application to CZCS imagery. An alternate method under study for affecting the atmospheric correction requires a knowledge of 'clear water' subsurface upwelled radiance as a function of solar angle and pigment concentration.

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

    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.

  9. Atmospheric compensation with a speckle beacon in strong scintillation conditions: directed energy and laser communication applications.

    PubMed

    Weyrauch, Thomas; Vorontsov, Mikhail A

    2005-10-20

    Wavefront control experiments in strong scintillation conditions (scintillation index, approximately equal to 1) over a 2.33 km, near-horizontal, atmospheric propagation path are presented. The adaptive-optics system used comprises a tracking and a fast-beam-steering mirror as well as a 132-actuator, microelectromechanical-system, piston-type deformable mirror with a VLSI controller that implements stochastic parallel gradient descent control optimization of a system performance metric. The experiments demonstrate mitigation of atmospheric distortions with a speckle beacon typical for directed energy and free-space laser communication applications. PMID:16252651

  10. Motion-compensated cone beam computed tomography using a conjugate gradient least-squares algorithm and electrical impedance tomography imaging motion data.

    PubMed

    Pengpen, T; Soleimani, M

    2015-06-13

    Cone beam computed tomography (CBCT) is an imaging modality that has been used in image-guided radiation therapy (IGRT). For applications such as lung radiation therapy, CBCT images are greatly affected by the motion artefacts. This is mainly due to low temporal resolution of CBCT. Recently, a dual modality of electrical impedance tomography (EIT) and CBCT has been proposed, in which the high temporal resolution EIT imaging system provides motion data to a motion-compensated algebraic reconstruction technique (ART)-based CBCT reconstruction software. High computational time associated with ART and indeed other variations of ART make it less practical for real applications. This paper develops a motion-compensated conjugate gradient least-squares (CGLS) algorithm for CBCT. A motion-compensated CGLS offers several advantages over ART-based methods, including possibilities for explicit regularization, rapid convergence and parallel computations. This paper for the first time demonstrates motion-compensated CBCT reconstruction using CGLS and reconstruction results are shown in limited data CBCT considering only a quarter of the full dataset. The proposed algorithm is tested using simulated motion data in generic motion-compensated CBCT as well as measured EIT data in dual EIT-CBCT imaging. PMID:25939625

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

    NASA Technical Reports Server (NTRS)

    Wang, Menghua

    2003-01-01

    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.

  12. Airborne imaging spectrometer-2 - Radiometric spectral characteristics and comparison of ways to compensate for the atmosphere

    NASA Technical Reports Server (NTRS)

    Conel, James E.; Green, Robert O.; Vane, Gregg; Bruegge, Carol J.; Alley, Ronald E.

    1988-01-01

    The reduction of AIS data to spectral radiance utilizing the detector responsivity equations developed by a laboratory calibration of the instrument with a BaSO4-coated integrating sphere is described. Estimates of the signal-to-noise ratio for laboratory and flight conditions are obtained. In addition, the effective in-flight instrumental spectral sampling interval is estimated by using atmospheric CO2 absorption lines generated from LOWTRAN simulations.

  13. 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)

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

    2003-01-01

    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.

  14. An improved algorithm of temperature compensation for a near infrared multiple-acquisition system based on two-dimensional regression analysis.

    PubMed

    Yu, Xu-yao; An, Jia-bao; Yu, Hui; Shi, Yao; Deng, Yong; Zhou, Jia-lu; Xu, Ke-xin

    2015-08-01

    The near infrared (NIR) spectroscopy analytical technique is one of the most advanced and promising tools in many domains. NIR acquisition is easily influenced by temperature, thereby affecting qualitative and quantitative analyses. In this paper, a temperature compensation model was established between NIR signals and output voltage values based on two-dimensional regression analysis. The effectiveness of the proposed compensation scheme was experimentally demonstrated by the measurement of six super luminescent diode sources at 293-313 K. The coefficient of variation was decreased 2-fold with this compensation algorithm. The results indicated that it was suitable for various NIR spectral acquisition systems with lower complexity and a higher signal-noise-ratio after being applied to an acousto-optic-tunable-filter system. PMID:26329222

  15. An improved algorithm of temperature compensation for a near infrared multiple-acquisition system based on two-dimensional regression analysis

    NASA Astrophysics Data System (ADS)

    Yu, Xu-yao; An, Jia-bao; Yu, Hui; Shi, Yao; Deng, Yong; Zhou, Jia-lu; Xu, Ke-xin

    2015-08-01

    The near infrared (NIR) spectroscopy analytical technique is one of the most advanced and promising tools in many domains. NIR acquisition is easily influenced by temperature, thereby affecting qualitative and quantitative analyses. In this paper, a temperature compensation model was established between NIR signals and output voltage values based on two-dimensional regression analysis. The effectiveness of the proposed compensation scheme was experimentally demonstrated by the measurement of six super luminescent diode sources at 293-313 K. The coefficient of variation was decreased 2-fold with this compensation algorithm. The results indicated that it was suitable for various NIR spectral acquisition systems with lower complexity and a higher signal-noise-ratio after being applied to an acousto-optic-tunable-filter system.

  16. Mars Entry Atmospheric Data System Trajectory Reconstruction Algorithms and Flight Results

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  17. Atmospheric correction algorithm for multiangular satellite measurements in the solar spectrum

    NASA Astrophysics Data System (ADS)

    Guanter, Luis; Marti, Jose M.; Moreno, Jose F.

    2004-02-01

    Multiangular and hyperspectral capabilities of the last generation of remote sensing sensors require new data processing algorithms that can take advantage of this new type of information. In terms of atmospheric correction, taking into account surface directional reflectance properties leads to a coupling between surface and atmospheric radiative transfer effects that cannot be analitically decoupled in the most general case, so other strategies must be developed. In addition to this, commonly used radiative transfer codes are based on a plane-parallel atmosphere approximation, what causes problems for large view and illumination zenith angles. The aim of this paper is to present an atmospheric correction method based on Vermote et al. scheme for MODIS atmospheric correction. It considers BRDF effects in the surface, improving 6S code calculations in off-nadir configurations . We have simulated the top-of-the-atmosphere reflectances using nine different natural surfaces by means of MODTRAN4 radiative transfer code. The reflectance angular pattern retrieved for each surface has allowed us to validate the model and check the improvements versus the original MODIS algorithm.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  19. Construction of the SILAM Eulerian atmospheric dispersion model based on the advection algorithm of Michael Galperin

    NASA Astrophysics Data System (ADS)

    Sofiev, M.; Vira, J.; Kouznetsov, R.; Prank, M.; Soares, J.; Genikhovich, E.

    2015-11-01

    The paper presents the transport module of the System for Integrated modeLling of Atmospheric coMposition SILAM v.5 based on the advection algorithm of Michael Galperin. This advection routine, so far weakly presented in the international literature, is positively defined, stable at any Courant number, and efficient computationally. We present the rigorous description of its original version, along with several updates that improve its monotonicity and shape preservation, allowing for applications to long-living species in conditions of complex atmospheric flows. The scheme is connected with other parts of the model in a way that preserves the sub-grid mass distribution information that is a cornerstone of the advection algorithm. The other parts include the previously developed vertical diffusion algorithm combined with dry deposition, a meteorological pre-processor, and chemical transformation modules. The quality of the advection routine is evaluated using a large set of tests. The original approach has been previously compared with several classic algorithms widely used in operational dispersion models. The basic tests were repeated for the updated scheme and extended with real-wind simulations and demanding global 2-D tests recently suggested in the literature, which allowed one to position the scheme with regard to sophisticated state-of-the-art approaches. The advection scheme performance was fully comparable with other algorithms, with a modest computational cost. This work was the last project of Dr. Sci. Michael Galperin, who passed away on 18 March 2008.

  20. Refraction in planetary atmospheres: improved analytical expressions and comparison with a new ray-tracing algorithm

    NASA Astrophysics Data System (ADS)

    Bétrémieux, Yan; Kaltenegger, Lisa

    2015-08-01

    Atmospheric refraction affects to various degrees exoplanet transit, lunar eclipse, as well as stellar occultation observations. Exoplanet retrieval algorithms often use analytical expressions for the column abundance along a ray traversing the atmosphere as well as for the deflection of that ray, which are first-order approximations valid for low densities in a spherically symmetric homogeneous isothermal atmosphere. We derive new analytical formulae for both of these quantities, which are valid for higher densities, and use them to refine and validate a new ray-tracing algorithm which can be used for arbitrary atmospheric temperature-pressure profiles. We illustrate with simple isothermal atmospheric profiles the consequences of our model for different planets: temperate Earth-like and Jovian-like planets, as well as HD 189733b, and GJ1214b. We find that, for both hot exoplanets, our treatment of refraction does not make much of a difference to pressures as high as 10 atm, but that it is important to consider the variation of gravity with altitude for GJ1214b. However, we find that the temperate atmospheres have an apparent scaleheight significantly smaller than their actual density scaleheight at densities larger than 1 amagat, thus increasing the difficulty of detecting spectral features originating in these regions. These denser atmospheric regions form a refractive boundary layer where column abundances and ray deflection increases dramatically with decreasing impact parameter. This refractive boundary layer mimics a surface, and none of the techniques mentioned above can probe atmospheric regions denser than about 4 amagat on these temperate planets.

  1. Development of an Aircraft Approach and Departure Atmospheric Profile Generation Algorithm

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

  3. Direct variational data assimilation algorithm for atmospheric chemistry data with transport and transformation model

    NASA Astrophysics Data System (ADS)

    Penenko, Alexey; Penenko, Vladimir; Nuterman, Roman; Baklanov, Alexander; Mahura, Alexander

    2015-11-01

    Atmospheric chemistry dynamics is studied with convection-diffusion-reaction model. The numerical Data Assimilation algorithm presented is based on the additive-averaged splitting schemes. It carries out ''fine-grained'' variational data assimilation on the separate splitting stages with respect to spatial dimensions and processes i.e. the same measurement data is assimilated to different parts of the split model. This design has efficient implementation due to the direct data assimilation algorithms of the transport process along coordinate lines. Results of numerical experiments with chemical data assimilation algorithm of in situ concentration measurements on real data scenario have been presented. In order to construct the scenario, meteorological data has been taken from EnviroHIRLAM model output, initial conditions from MOZART model output and measurements from Airbase database.

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  7. Algorithm for Simulating Atmospheric Turbulence and Aeroelastic Effects on Simulator Motion Systems

    NASA Technical Reports Server (NTRS)

    Ercole, Anthony V.; Cardullo, Frank M.; Kelly, Lon C.; Houck, Jacob A.

    2012-01-01

    Atmospheric turbulence produces high frequency accelerations in aircraft, typically greater than the response to pilot input. Motion system equipped flight simulators must present cues representative of the aircraft response to turbulence in order to maintain the integrity of the simulation. Currently, turbulence motion cueing produced by flight simulator motion systems has been less than satisfactory because the turbulence profiles have been attenuated by the motion cueing algorithms. This report presents a new turbulence motion cueing algorithm, referred to as the augmented turbulence channel. Like the previous turbulence algorithms, the output of the channel only augments the vertical degree of freedom of motion. This algorithm employs a parallel aircraft model and an optional high bandwidth cueing filter. Simulation of aeroelastic effects is also an area where frequency content must be preserved by the cueing algorithm. The current aeroelastic implementation uses a similar secondary channel that supplements the primary motion cue. Two studies were conducted using the NASA Langley Visual Motion Simulator and Cockpit Motion Facility to evaluate the effect of the turbulence channel and aeroelastic model on pilot control input. Results indicate that the pilot is better correlated with the aircraft response, when the augmented channel is in place.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  9. The Algorithm Theoretical Basis Document for the GLAS Atmospheric Data Products

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

  10. An improved atmospheric correction algorithm for applying MERIS data to very turbid inland waters

    NASA Astrophysics Data System (ADS)

    Jaelani, Lalu Muhamad; Matsushita, Bunkei; Yang, Wei; Fukushima, Takehiko

    2015-07-01

    Atmospheric correction (AC) is a necessary process when quantitatively monitoring water quality parameters from satellite data. However, it is still a major challenge to carry out AC for turbid coastal and inland waters. In this study, we propose an improved AC algorithm named N-GWI (new standard Gordon and Wang's algorithms with an iterative process and a bio-optical model) for applying MERIS data to very turbid inland waters (i.e., waters with a water-leaving reflectance at 864.8 nm between 0.001 and 0.01). The N-GWI algorithm incorporates three improvements to avoid certain invalid assumptions that limit the applicability of the existing algorithms in very turbid inland waters. First, the N-GWI uses a fixed aerosol type (coastal aerosol) but permits aerosol concentration to vary at each pixel; this improvement omits a complicated requirement for aerosol model selection based only on satellite data. Second, it shifts the reference band from 670 nm to 754 nm to validate the assumption that the total absorption coefficient at the reference band can be replaced by that of pure water, and thus can avoid the uncorrected estimation of the total absorption coefficient at the reference band in very turbid waters. Third, the N-GWI generates a semi-analytical relationship instead of an empirical one for estimation of the spectral slope of particle backscattering. Our analysis showed that the N-GWI improved the accuracy of atmospheric correction in two very turbid Asian lakes (Lake Kasumigaura, Japan and Lake Dianchi, China), with a normalized mean absolute error (NMAE) of less than 22% for wavelengths longer than 620 nm. However, the N-GWI exhibited poor performance in moderately turbid waters (the NMAE values were larger than 83.6% in the four American coastal waters). The applicability of the N-GWI, which includes both advantages and limitations, was discussed.

  11. [A quickly atmospheric correction method for HJ-1 CCD with deep blue algorithm].

    PubMed

    Wang, Zhong-Ting; Wang, Hong-Mei; Li, Qing; Zhao, Shao-Hua; Li, Shen-Shen; Chen, Liang-Fu

    2014-03-01

    In the present, for the characteristic of HJ-1 CCD camera, after receiving aerosol optical depth (AOD) from deep blue algorithm which was developed by Hsu et al. assisted by MODerate-resolution imaging spectroradiometer (MODIS) surface reflectance database, bidirectional reflectance distribution function (BRDF) correction with Kernel-Driven Model, and the calculation of viewing geometry with auxiliary data, a new atmospheric correction method of HJ-1 CCD was developed which can be used over vegetation, soil and so on. And, when the CCD data is processed to correct atmospheric influence, with look up table (LUT) and bilinear interpolation, atmospheric correction of HJ-1 CCD is completed quickly by grid calculation of atmospheric parameters and matrix operations of interface define language (IDL). The experiment over China North Plain on July 3rd, 2012 shows that by our method, the atmospheric influence was corrected well and quickly (one CCD image of 1 GB can be corrected in eight minutes), and the reflectance after correction over vegetation and soil was close to the spectrum of vegetation and soil. The comparison with MODIS reflectance product shows that for the advantage of high resolution, the corrected reflectance image of HJ-1 is finer than that of MODIS, and the correlation coefficient of the reflectance over typical surface is greater than 0.9. Error analysis shows that the recognition error of aerosol type leads to 0. 05 absolute error of surface reflectance in near infrared band, which is larger than that in visual bands, and the 0. 02 error of reflectance database leads to 0.01 absolute error of surface reflectance of atmospheric correction in green and red bands. PMID:25208402

  12. An Atmospheric Correction Algorithm Over Coastal and Inland Waters For The Siscal Project

    NASA Astrophysics Data System (ADS)

    Dilligeard, E.; Ramon, D.; Vidot, J.; Santer, R.

    SISCAL is a pan-European project dedicated to develop facilities to provide end users with customize and easy-to-use Earth Observation data for environmental monitoring of European coastal areas, lakes and open oceans. The main task will be to create a software processor providing near-real-time information on the aquatic ecosystems, derived from satellite data. The Universit du Littoral in collaboration with the HY- GEOS Firm develop an atmospheric algorithm which will be implemented in the pro- cessor . The algorithm corrects the various SISCAL Ocean Colour sensors from atmo- spheric effects over waters and inland waters. It processes SeaWiFS, MODIS, MERIS, GLI Top of Atmosphere radiances that comes from Level 1B images and provides spectral marine reflectance under the water surface. This is done for all bands that are near SeaWiFS bands. Over waters we apply a correction for scattering effects similar to SeaWiFS and referenced here as a Gordon and Wang Scheme. Over land, the algo- rithm developed by Ramon, Vidot and Santer has been adapted. The aerosol retrieval is made over Dense Dark Vegetation pixel. Besides these main outputs some flags and quality indices are given in order to assess the product quality and the product environment.

  13. Single star scidar: atmospheric parameters profiling using the simulated annealing algorithm

    NASA Astrophysics Data System (ADS)

    Habib, A.; Vernin, J.; Benkhaldoun, Z.; Lanteri, H.

    2006-05-01

    In this paper, we present a new method to estimate, for each turbulent layer labelled i, the horizontal wind speed v(hi), the standard deviation of the horizontal wind speed fluctuations ?v(hi) and the integrated value of C2n over the thickness ?hi of the turbulent layer C2n(hi)?hi, where hi is the altitude of the turbulent layer. These parameters are extracted from single star scintillation spatiotemporal cross-correlation functions of atmospheric speckles obtained within the generalized mode. This method is based on the simulated annealing algorithm to find the optimal solution required to solve the problem. Astrophysics parameters for adaptive optics are also calculated using C2n(hi) and v (hi) values. The results of other techniques support this new method.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    SciTech Connect

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

    1994-03-01

    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.

  16. Compensating for Camera Translation in Video Eye Movement Recordings by Tracking a Representative Landmark Selected Automatically by a Genetic Algorithm

    PubMed Central

    Karmali, Faisal; Shelhamer, Mark

    2013-01-01

    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 inherits 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, even with camera translations of 2.5 mm at a viewing distance of 120 mm, which would cause an error of 11 without correction. PMID:18835407

  17. An algorithm for variational data assimilation of contact concentration measurements for atmospheric chemistry models

    NASA Astrophysics Data System (ADS)

    Penenko, Alexey; Penenko, Vladimir

    2014-05-01

    Contact concentration measurement data assimilation problem is considered for convection-diffusion-reaction models originating from the atmospheric chemistry study. High dimensionality of models imposes strict requirements on the computational efficiency of the algorithms. Data assimilation is carried out within the variation approach on a single time step of the approximated model. A control function is introduced into the source term of the model to provide flexibility for data assimilation. This function is evaluated as the minimum of the target functional that connects its norm to a misfit between measured and model-simulated data. In the case mathematical model acts as a natural Tikhonov regularizer for the ill-posed measurement data inversion problem. This provides flow-dependent and physically-plausible structure of the resulting analysis and reduces a need to calculate model error covariance matrices that are sought within conventional approach to data assimilation. The advantage comes at the cost of the adjoint problem solution. This issue is solved within the frameworks of splitting-based realization of the basic convection-diffusion-reaction model. The model is split with respect to physical processes and spatial variables. A contact measurement data is assimilated on each one-dimensional convection-diffusion splitting stage. In this case a computationally-efficient direct scheme for both direct and adjoint problem solution can be constructed based on the matrix sweep method. Data assimilation (or regularization) parameter that regulates ratio between model and data in the resulting analysis is obtained with Morozov discrepancy principle. For the proper performance the algorithm takes measurement noise estimation. In the case of Gaussian errors the probability that the used Chi-squared-based estimate is the upper one acts as the assimilation parameter. A solution obtained can be used as the initial guess for data assimilation algorithms that assimilate outside the splitting stages and involve iterations. Splitting method stage that is responsible for chemical transformation processes is realized with the explicit discrete-analytical scheme with respect to time. The scheme is based on analytical extraction of the exponential terms from the solution. This provides unconditional positive sign for the evaluated concentrations. Splitting-based structure of the algorithm provides means for efficient parallel realization. The work is partially supported by the Programs No 4 of Presidium RAS and No 3 of Mathematical Department of RAS, by RFBR project 11-01-00187 and Integrating projects of SD RAS No 8 and 35. Our studies are in the line with the goals of COST Action ES1004.

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

    NASA Astrophysics Data System (ADS)

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

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

  19. Algorithms

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The implementation of the algorithms used in the flight program to approximate elementary functions and mathematical procedures was checked. This was done by verifying that at least one, and in most cases, more than one function computed through the use of the algorithms was calculated properly. The following algorithms were checked: sine-cosine, arctangent, natural logarithm, square root, inverse square root, as well as the vector dot and cross products.

  20. 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

    Konstantinidis, Anastasios C.; Olivo, Alessandro; Speller, Robert D.

    2011-12-15

    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.

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

    NASA Technical Reports Server (NTRS)

    Korkin, S.; Lyapustin, A.

    2012-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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.

  3. An adaptive Bayesian inference algorithm to estimate the parameters of a hazardous atmospheric release

    NASA Astrophysics Data System (ADS)

    Rajaona, Harizo; Septier, Franois; Armand, Patrick; Delignon, Yves; Olry, Christophe; Albergel, Armand; Moussafir, Jacques

    2015-12-01

    In the eventuality of an accidental or intentional atmospheric release, the reconstruction of the source term using measurements from a set of sensors is an important and challenging inverse problem. A rapid and accurate estimation of the source allows faster and more efficient action for first-response teams, in addition to providing better damage assessment. This paper presents a Bayesian probabilistic approach to estimate the location and the temporal emission profile of a pointwise source. The release rate is evaluated analytically by using a Gaussian assumption on its prior distribution, and is enhanced with a positivity constraint to improve the estimation. The source location is obtained by the means of an advanced iterative Monte-Carlo technique called Adaptive Multiple Importance Sampling (AMIS), which uses a recycling process at each iteration to accelerate its convergence. The proposed methodology is tested using synthetic and real concentration data in the framework of the Fusion Field Trials 2007 (FFT-07) experiment. The quality of the obtained results is comparable to those coming from the Markov Chain Monte Carlo (MCMC) algorithm, a popular Bayesian method used for source estimation. Moreover, the adaptive processing of the AMIS provides a better sampling efficiency by reusing all the generated samples.

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

    NASA Technical Reports Server (NTRS)

    Spratlin, Kenneth Milton

    1987-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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 Chausses, 2002. im?nek, J., M. Th. van Genuchten, and M. ejna, 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.

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

    NASA Astrophysics Data System (ADS)

    Schneider, Sbastien; Jacques, Diederik; Mallants, Dirk

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  8. 38 CFR 3.5 - Dependency and indemnity compensation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Geodetic Survey, the Environmental Science Services Administration, or the National Oceanic and Atmospheric... indemnity compensation. (a) Dependency and indemnity compensation. This term means a monthly payment made...

  9. 38 CFR 3.5 - Dependency and indemnity compensation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Geodetic Survey, the Environmental Science Services Administration, or the National Oceanic and Atmospheric... indemnity compensation. (a) Dependency and indemnity compensation. This term means a monthly payment made...

  10. 38 CFR 3.5 - Dependency and indemnity compensation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Geodetic Survey, the Environmental Science Services Administration, or the National Oceanic and Atmospheric... indemnity compensation. (a) Dependency and indemnity compensation. This term means a monthly payment made...

  11. 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)

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

    1979-01-01

    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.

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

    SciTech Connect

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

    1999-07-01

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

  13. Comparison of atmospheric correction algorithms for the Coastal Zone Color Scanner

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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.

  14. Motion compensation for ultra wide band SAR

    NASA Technical Reports Server (NTRS)

    Madsen, S.

    2001-01-01

    This paper describes an algorithm that combines wavenumber domain processing with a procedure that enables motion compensation to be applied as a function of target range and azimuth angle. First, data are processed with nominal motion compensation applied, partially focusing the image, then the motion compensation of individual subpatches is refined. The results show that the proposed algorithm is effective in compensating for deviations from a straight flight path, from both a performance and a computational efficiency point of view.

  15. Genetic algorithm applied to a Soil-Vegetation-Atmosphere system: Calibration and model abstraction

    NASA Astrophysics Data System (ADS)

    Schneider, Sbastien; Jacques, Diederik; Mallants, Dirk

    2010-05-01

    To model complex hydrological problems, realistic models and representative hydraulic properties are needed. In this study we investigate the ability of two different types of process description for water flow to quantify the water balance in a Soil-Vegetation-Atmosphere (SVA) system. A first model description is based on the Richards' equation for which the mechanistic numerical model HYDRUS-1D is used. The second model description is a compartment model assuming a bucket-type water flow process. We present calibrations of these two models performed for a SVA system developed in a podzol soil with Scots Pine vegetation. Due to a high non-linearity of the calibration problem, an efficient optimization technique is needed. Therefore a genetic algorithm, which belongs to the so-called evolutionary algorithms class, was used in this study. Aim of this work is both (i) calibrating the SVA system and (ii) testing abstraction techniques. Examples of both parameter and model structure abstraction will be presented. Calibrations of the soil hydraulic properties have been obtained using soil water content data collected at several depths with time domain reflectometry probes in two distinct lysimeters. All climatic data (throughfall and other meteorological data necessary for estimating the potential evaporation) and water contents at different soil depths have been recorded during one year at a daily time step in two lysimeters. The water table level, which is varying between 95 and 170 cm, has been recorded with intervals of 0.5 hour. The leaf area index was measured as well in order to evaluate the energy which reaches the soil and to deduce the potential evaporation. Ten scenarios have been elaborated and applied on the two lysimeters in order to investigate the impact of both the water balance process description (mechanistic or compartmental) and the number of horizons used for the profile description, on the calibration accuracy. Main results are that: (i) both model process descriptions are able to describe accurately the measured water contents at all depths when a high number of soil horizon was used, (ii) the mechanistic model performs better than the compartment model, (iii) the considered number of soil horizons is the major factor that controls the accuracy of the calibration. Finally, the compartment model is considered as an abstracted model from the reference model based on the mechanistic model. For instance, yearly drainage values predicted by both models are used to evaluate the performance of the abstracted model. It appears that drainages values simulated by the abstracted model were close to those of the reference model, provided that drainage values were averaged over a sufficiently large period (about 9 months). Therefore, this result suggests that values of drainage obtained with an abstracted model could be reliably simulated for sufficiently long time periods, with a significant gain in computational time compared to the mechanistic approach, and without an important loss of accuracy.

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

    NASA Astrophysics Data System (ADS)

    Korkin, S.; Lyapustin, A.

    2012-12-01

    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.

  17. Atmospheric Correction, Vicarious Calibration and Development of Algorithms for Quantifying Cyanobacteria Blooms from Oceansat-1 OCM Satellite Data

    NASA Astrophysics Data System (ADS)

    Dash, P.; Walker, N. D.; Mishra, D. R.; Hu, C.; D'Sa, E. J.; Pinckney, J. L.

    2011-12-01

    Cyanobacteria represent a major harmful algal group in fresh to brackish water environments. Lac des Allemands, a freshwater lake located southwest of New Orleans, Louisiana on the upper end of the Barataria Estuary, provides a natural laboratory for remote characterization of cyanobacteria blooms because of their seasonal occurrence. The Ocean Colour Monitor (OCM) sensor provides radiance measurements similar to SeaWiFS but with higher spatial resolution. However, OCM does not have a standard atmospheric correction procedure, and it is difficult to find a detailed description of the entire atmospheric correction procedure for ocean (or lake) in one place. Atmospheric correction of satellite data over small lakes and estuaries (Case 2 waters) is also challenging due to difficulties in estimation of aerosol scattering accurately in these areas. Therefore, an atmospheric correction procedure was written for processing OCM data, based on the extensive work done for SeaWiFS. Since OCM-retrieved radiances were abnormally low in the blue wavelength region, a vicarious calibration procedure was also developed. Empirical inversion algorithms were developed to convert the OCM remote sensing reflectance (Rrs) at bands centered at 510.6 and 556.4 nm to concentrations of phycocyanin (PC), the primary cyanobacterial pigment. A holistic approach was followed to minimize the influence of other optically active constituents on the PC algorithm. Similarly, empirical algorithms to estimate chlorophyll a (Chl a) concentrations were developed using OCM bands centered at 556.4 and 669 nm. The best PC algorithm (R2=0.7450, p<0.0001, n=72) yielded a root mean square error (RMSE) of 36.92 ?g/L with a relative RMSE of 10.27% (PC from 2.75-363.50 ?g/L, n=48). The best algorithm for Chl a (R2=0.7510, p<0.0001, n=72) produced an RMSE of 31.19 ?g/L with a relative RMSE of 16.56% (Chl a from 9.46-212.76 ?g/L, n=48). While more field data are required to further validate the long-term performance of the algorithms, currently they represent the best protocol for establishing a long time-series of cyanobacterial blooms in the Lac des Allemands using OCM data.

  18. Parallel implementation of high-speed, phase diverse atmospheric turbulence compensation method on a neural network-based architecture

    NASA Astrophysics Data System (ADS)

    Arrasmith, William W.; Sullivan, Sean F.

    2008-04-01

    Phase diversity imaging methods work well in removing atmospheric turbulence and some system effects from predominantly near-field imaging systems. However, phase diversity approaches can be computationally intensive and slow. We present a recently adapted, high-speed phase diversity method using a conventional, software-based neural network paradigm. This phase-diversity method has the advantage of eliminating many time consuming, computationally heavy calculations and directly estimates the optical transfer function from the entrance pupil phases or phase differences. Additionally, this method is more accurate than conventional Zernike-based, phase diversity approaches and lends itself to implementation on parallel software or hardware architectures. We use computer simulation to demonstrate how this high-speed, phase diverse imaging method can be implemented on a parallel, highspeed, neural network-based architecture-specifically the Cellular Neural Network (CNN). The CNN architecture was chosen as a representative, neural network-based processing environment because 1) the CNN can be implemented in 2-D or 3-D processing schemes, 2) it can be implemented in hardware or software, 3) recent 2-D implementations of CNN technology have shown a 3 orders of magnitude superiority in speed, area, or power over equivalent digital representations, and 4) a complete development environment exists. We also provide a short discussion on processing speed.

  19. All-Weather Sounding of Moisture and Temperature From Microwave Sensors Using a Coupled Surface/Atmosphere Inversion Algorithm

    NASA Astrophysics Data System (ADS)

    Boukabara, S. A.; Garrett, K.

    2014-12-01

    A one-dimensional variational retrieval system has been developed, capable of producing temperature and water vapor profiles in clear, cloudy and precipitating conditions. The algorithm, known as the Microwave Integrated Retrieval System (MiRS), is currently running operationally at the National Oceanic and Atmospheric Administration (NOAA) National Environmental Satellite Data and Information Service (NESDIS), and is applied to a variety of data from the AMSU-A/MHS sensors on board the NOAA-18, NOAA-19, and MetOp-A/B polar satellite platforms, as well as SSMI/S on board both DMSP F-16 and F18, and from the NPP ATMS sensor. MiRS inverts microwave brightness temperatures into atmospheric temperature and water vapor profiles, along with hydrometeors and surface parameters, simultaneously. This atmosphere/surface coupled inversion allows for more accurate retrievals in the lower tropospheric layers by accounting for the surface emissivity impact on the measurements. It also allows the inversion of the soundings in all-weather conditions thanks to the incorporation of the hydrometeors parameters in the inverted state vector as well as to the inclusion of the emissivity in the same state vector, which is accounted for dynamically for the highly variable surface conditions found under precipitating atmospheres. The inversion is constrained in precipitating conditions by the inclusion of covariances for hydrometeors, to take advantage of the natural correlations that exist between temperature and water vapor with liquid and ice cloud along with rain water. In this study, we present a full assessment of temperature and water vapor retrieval performances in all-weather conditions and over all surface types (ocean, sea-ice, land, and snow) using matchups with radiosonde as well as Numerical Weather Prediction and other satellite retrieval algorithms as references. An emphasis is placed on retrievals in cloudy and precipitating atmospheres, including extreme weather events, to assess the quality of soundings in these conditions. We will also assess the potential added value of considering the coupled inversion approach.

  20. An improved algorithm for extracting atmospheric motion vectors in cloud-free region from FY-2E thermal infrared imagery

    NASA Astrophysics Data System (ADS)

    Wang, Zhenhui; Zhang, Qing; Tang, Min; Zhao, Hang; Yang, Lu; Zhan, Yizhe

    2014-10-01

    Atmospheric motion vectors (AMV) in cloud-free region can not be obtained with current operational cloud-motion tracking and water-vapor channel algorithms. The motivation of this study is to introduce a supplementary algorithm in order to work out the low-level AMVs in the clear area with FY-2E long wave, window (10.3~11.5, 11.6~12.8 ?m) channel imagery. It has been shown that the weak signals indicating water vapor in "cloud-free region" can be extracted from FY-2E long wave infrared imagery and may be used as tracers for atmospheric motion vectors. The algorithm, named as Second Order difference method, has been raised in order to weaken the surface temperature interference to the weak signals of water vapor in "cloud-free region" by means of split window and temporal difference calculations. The results from theory analysis and cases study show that this method can make up for the wind data in regions lack of cloud but rich of water vapor and comparison between the wind vectors from this method and the NCEP reanalysis data shows a good consistency.

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Rood, Richard B.

    1987-01-01

    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.

  3. Teacher Compensation.

    ERIC Educational Resources Information Center

    Minnesota State Office of the Legislative Auditor, St. Paul. Program Evaluation Div.

    Minnesota state policy makers are concerned about teacher compensation because it constitutes a major category of state and local spending and can affect education results. This report examines compensation issues by describing the pay structure of Minnesota's K-12 public school teachers, making pay comparisons with other professionals, and

  4. Correction for atmospheric distortion of multichannel laser radiation with the use of phase-conjugation algorithm

    NASA Astrophysics Data System (ADS)

    Antopov, Oleg; Kanev, Feodor; Makenova, Nailia; Lukin, Vladimir

    2015-11-01

    The results of numeric simulation are presented in the paper of multichannel laser radiation propagation under conditions of free diffraction and in a turbulent atmosphere. It was shown that in free space a multichannel system allows one to obtain higher concentration (20-50%) of radiation energy on the object comparing with a Gaussian beam. Intensity of atmospheric distortion decreases with increase of the number of channels. Adaptive correction for turbulent distortions results in two-times increase of energy concentration for systems with 9 and 81 channels. For systems with greater number of channels (201 channels) the results of correction do not depend on turbulence intensity.

  5. Constraining the Structure of Hot Jupiter Atmospheres Using a Hybrid Version of the NEMESIS Retrieval Algorithm

    NASA Astrophysics Data System (ADS)

    Badhan, Mahmuda A.; Mandell, Avi M.; Hesman, Brigette; Nixon, Conor; Deming, Drake; Irwin, Patrick; Barstow, Joanna; Garland, Ryan

    2015-11-01

    Understanding the formation environments and evolution scenarios of planets in nearby planetary systems requires robust measures for constraining their atmospheric physical properties. Here we have utilized a combination of two different parameter retrieval approaches, Optimal Estimation and Markov Chain Monte Carlo, as part of the well-validated NEMESIS atmospheric retrieval code, to infer a range of temperature profiles and molecular abundances of H2O, CO2, CH4 and CO from available dayside thermal emission observations of several hot-Jupiter candidates. In order to keep the number of parameters low and henceforth retrieve more plausible profile shapes, we have used a parametrized form of the temperature profile based upon an analytic radiative equilibrium derivation in Guillot et al. 2010 (Line et al. 2012, 2014). We show retrieval results on published spectroscopic and photometric data from both the Hubble Space Telescope and Spitzer missions, and compare them with simulations from the upcoming JWST mission. In addition, since NEMESIS utilizes correlated distribution of absorption coefficients (k-distribution) amongst atmospheric layers to compute these models, updates to spectroscopic databases can impact retrievals quite significantly for such high-temperature atmospheres. As high-temperature line databases are continually being improved, we also compare retrievals between old and newer databases.

  6. Atmospheric correction algorithm for satellite ocean color data over Asian waters

    NASA Astrophysics Data System (ADS)

    Fukushima, Hajime; Toratani, Mitsuhiro; Kobayashi, Hiroshi; Takahashi, Wataru; Tanaka, Akihiko; Sohn, Byung-Ju

    2001-01-01

    The presentation focuses on the peculiarity of Asian waters with respect to the atmospheric correction of the satellite ocean color data such as of Ocean Color and Temperature Scanner (OCTS). We first demonstrate the effect of highly turbid case 2 waters on the atmospheric correction via non- zero water reflectance in the near infrared region. The results of applying the OCTS standard correction scheme to typical Chinese coastal OCTS scenes reveal that a significant portion of the area is masked due to the negative water reflectance retrieved by the scheme, even using 765 nm and 865 nm bands instead of 670 and 865 nm pair to determine aerosol contribution. An optical model that relates suspended solid (SS) and chlorophyll-a (Chl-a) concentrations to the near infrared water reflectances was implemented into the atmospheric correction, together with a neural network that estimates Chl-a and SS concentrations. The new iterative scheme is applied to the Chinese coastal scenes and the results are assessed to be favorable. The paper then discuss the modeling of Asian dust aerosol in hope of establishing aerosol models that can be used for atmospheric correction. A set of models are designed with varying controlling parameters such as size distribution, vertical profile, and imaginary part of the refractive index. A series of radiative transfer simulation is conducted and the spectrum of the top-of- atmosphere radiance is compared to that of a Sea Wide Filed- of-view Scanner (SeaWiFS) data obtained under Asian dust event. The results of the comparison suggest that the Asian dust aerosol has unique spectral absorption feature at the blue region (in 412 nm band, i.e.).

  7. Radiative transfer model MCC++ with evaluation of weighting functions in spherical atmosphere for usage in retrieval algorithms

    NASA Astrophysics Data System (ADS)

    Postylyakov, O.

    Accurate and quick model for calculations of intensity and weighting functions are the basis for development of algorithms for retrieval of ozone and trace gases using space measurements of limb and nadir intensities of scattered solar radiation. MCC++ model, which was developed for usage in retrieval algorithms, simulates radiative transfer in spherically symmetrical atmosphere taking into account all orders of scattering. A new quick algorithm for simultaneous evaluation of weighting functions together with intensity spends only 1.2-1.8 times as much time as calculation of intensity alone. The model takes into account surface albedo, aerosol scattering and absorption. It is coded at C++, that made possible widely to use code recycling. Like the C++ templates are released: (1) two radiative transfer models: vector (with polarization) and scalar; (2) a few methods of intensity and weighting function calculations: (a) Monte Carlo method of conjugate walk ; (b) Monte Carlo method of modified double local estimation; (c) the direct integration for single scattering; and (d) mixed models (which have the best calculation speed) with calculation of multiple scattering by Monte Carlo method (a) or (b) and single scattering calculation by method (c); (3) two kinds of distribution of scattering and absorption between grid points: uniform and linear changing. MCC++ model has a good speed of calculation. For example, in extended Brewer Umkehr retrieval algorithm the vector release of MCC++ calculates a set of zenith sky intensities and weighting functions in 48 points {a grid of 8 solar zenith angles (from 77 to 90 degree) to 6 wavelengths (from 306.3 to 329.5 nm)} with precision 0.13-0.99% using 20 min at personal computer. MCC++ model took part in intercomparisons with other models, including comparison of weighting function calculations, calculations in limb geometry, calculations for solar zenith angles up to 96 degree.

  8. Remote Sensing of the Earth s Atmosphere by the Spaceborne Occultation Radiometer, ORA: Final Inversion Algorithm

    NASA Astrophysics Data System (ADS)

    Fussen, Didier; Vanhellemont, Filip; Bingen, Christine

    2001-02-01

    We describe the final inversion algorithm developed to process solar occultation data measured in 1992 -1993 by the Occultation Radiometer (ORA) spaceborne experiment. First we develop a new method to improve the ORA total extinction altitude profiles retrieved with the previously described Natural Orthogonal Polynomial Expansion (NOPE) method. Using these improved profiles, we perform spectral inversion and obtain altitude density profiles for O3 and NO2 and extinction profiles for the aerosols. Validation of number density profiles between the Stratospheric Aerosol and Gas Experiment II (SAGE II) and the ORA shows satisfactory agreement.

  9. CGI delay compensation

    NASA Technical Reports Server (NTRS)

    Mcfarland, Richard E.

    1986-01-01

    Computer-generated graphics in real-time helicopter simulation produces objectionable scene-presentation time delays. In the flight simulation laboratory at Ames Research Center, it has been determined that these delays have an adverse influence on pilot performance during aggressive tasks such as nap-of-the-earth (NOE) maneuvers. Using contemporary equipment, computer-generated image (CGI) time delays are an unavoidable consequence of the operations required for scene generation. However, providing that magnitide distortions at higher frequencies are tolerable, delay compensation is possible over a restricted frequency range. This range, assumed to have an upper limit of perhaps 10 or 15 rad/sec, conforms approximately to the bandwidth associated with helicopter handling qualities research. A compensation algorithm is introduced here and evaluated in terms of tradeoffs in frequency responses. The algorithm has a discrete basis and accommodates both a large, constant transport delay interval and a periodic delay interval, as associated with asynchronous operations.

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

    USGS Publications Warehouse

    Watson, K.; Hummer-Miller, S.

    1981-01-01

    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.

  11. 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)

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

    2001-01-01

    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.

  12. Estimation of the error of the algorithm for reconstructing the reflection coefficient of the Earth surface on the example of images with the low atmospheric turbidity

    NASA Astrophysics Data System (ADS)

    Belov, V. V.; Tarasenkov, M. V.

    2015-11-01

    An algorithm for atmospheric correction of satellite images combining the consideration of the main factors influencing imaging and a number of techniques allowing the computational time to be decreased considerably is analyzed. On the example of a series of images of the South of the Tomsk Region recorded from 7/13/2013 to 7/17/2013 with the low atmospheric turbidity, a comparison of the results of atmospheric correction using the suggested algorithm with the results obtained using the NASA MOD09 algorithm is performed. The correction error is estimated under assumption of a linear change of the reflection coefficient from image to image. Our comparison demonstrates that the results of correction differ within the correction error.

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

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Blaisdell, John; Iredell, Lena

    2010-01-01

    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.

  14. Targeting Atmospheric Simulation Algorithms for Large Distributed Memory GPU Accelerated Computers

    SciTech Connect

    Norman, Matthew R

    2013-01-01

    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.

  15. A novel atmospheric turbulence-degraded image restoration algorithm based on support vector regression

    NASA Astrophysics Data System (ADS)

    Liu, Chun-sheng; Li, Ming

    2006-11-01

    A novel method based on support vector regression is presented for atmospheric turbulence-degraded image restoration. Firstly, an operation with a sliding window is employed to the images to analyze the correlation between pixels of clear image and 8 neighbors of corresponding pixels of degraded image. After feature selection, we get training samples. Secondly, an appropriate kernel function is employed to map the training samples into a higher space. Through linear learning machine in kernel feature space, we get non-linear function. Then the relationship between clear images and degraded images is constructed via regression analysis of the training samples by a support vector machine. Thus the model for turbulence-degraded image restoration is constructed here. Finally, the degraded images to be tested are restored by this model. The experimental results show that the proposed method has lower NMSE and higher PSNR and runs faster than classical image restoration methods such as Wiener Filter, Iterative Blind Deconvolution and etc.

  16. Compensable Transactions

    NASA Astrophysics Data System (ADS)

    Hoare, Tony

    The concept of a compensable transaction has been embodied in modern business workflow languages like BPEL. This article uses the concept of a box-structured Petri net to formalise the definition of a compensable transaction. The standard definitions of structured program connectives are extended to construct longer-running transactions out of shorter fine-grain ones. Floyd-type assertions on the arcs of the net specify the intended properties of the transaction and of its component programs. The correctness of the whole transaction can therefore be proved by local reasoning.

  17. Employee Compensation.

    ERIC Educational Resources Information Center

    Osif, Bonnie A.; Harwood, Richard L.

    1995-01-01

    Presents an overview of selected literature about employee compensation. Highlights include the foundations of reward and recognition systems, incentive plans, problems with merit pay, a historical perspective on performance pay, evaluation criteria and processes, self-rating, job motivation and satisfaction, employee attitudes, collective

  18. Detection of atmospheric rivers: Evaluation and application of an algorithm for global studies

    NASA Astrophysics Data System (ADS)

    Guan, Bin; Waliser, Duane E.

    2015-12-01

    Atmospheric rivers (ARs) are narrow, elongated, synoptic jets of water vapor that play important roles in the global water cycle and regional weather/hydrology. A technique is developed for objective detection of ARs on the global domain based on characteristics of the integrated water vapor transport (IVT). AR detection involves thresholding 6-hourly fields of ERA-Interim IVT based on the 85th percentile specific to each season and grid cell and a fixed lower limit of 100 kg m-1 s-1 and checking for the geometry requirements of length >2000 km, length/width ratio >2, and other considerations indicative of AR conditions. Output of the detection includes the AR shape, axis, landfall location, and basic statistics of each detected AR. The performance of the technique is evaluated by comparison to AR detection in the western North America, Britain, and East Antarctica with three independently conducted studies using different techniques, with over ~90% agreement in AR dates. Among the parameters tested, AR detection shows the largest sensitivity to the length criterion in terms of changes in the resulting statistical distribution of AR intensity and geometry. Global distributions of key AR characteristics are examined, and the results highlight the global footprints of ARs and their potential importance on global and regional scales. Also examined are seasonal dependence of AR frequency and precipitation and their modulation by four prominent modes of large-scale climate variability. The results are in broad consistency with previous studies that focused on landfalling ARs in the west coasts of North America and Europe.

  19. Non-reciprocity compensation correction and antenna selection for optical large MIMO system

    NASA Astrophysics Data System (ADS)

    Chen, Jie; Chi, Xue-fen; Zhao, Lin-lin

    2015-11-01

    This paper exploits an optical large multiple input multiple output (MIMO) system. We first establish the non-reciprocity compensation correction factor to solve the channel non-reciprocity problem. Then we propose an antenna selection algorithm with the goal of realizing maximum energy efficiency ( EE) when satisfying the outage EE. The simulation results prove that this non-reciprocity compensation correction factor can compensate beam energy attenuation gap and spatial correlation gap between uplink and downlink effectively, and this antenna selection algorithm can economize the number of transmit antennas and achieve high EE performance. Finally, we apply direct current- biased optical orthogonal frequency division multiplexing (DCO-OFDM) modulation in our system and prove that it can improve the bit error rate ( BER) compared with on-off keying (OOK) modulation, so the DCO-OFDM modulation can resist atmospheric turbulence effectively.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  1. An observer-based compensator for distributed delays

    NASA Technical Reports Server (NTRS)

    Luck, Rogelio; Ray, Asok

    1990-01-01

    This paper presents an algorithm for compensating delays that are distributed between the sensor(s), controller and actuator(s) within a control loop. This observer-based algorithm is specially suited to compensation of network-induced delays in integrated communication and control systems. The robustness of the algorithm relative to plant model uncertainties has been examined.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

  4. Application of a digital non-linear compensation algorithm for evaluating the performance of root-raised-cosine pulses in 112 Gbit s-1 DP-QPSK transmission

    NASA Astrophysics Data System (ADS)

    Asif, Rameez; Usman, Muhammad; Lin, Chien-Yu; Schmauss, Bernhard

    2012-09-01

    In this paper, we numerically investigate the non-linear tolerance of root-raised-cosine (RRC) pulse shaping by interpolating finite impulse response (FIR) filters in conjunction with digital backward propagation (DBP) in coherent 112 Gbit s-1 dual-polarization quadrature phase shift keying (DP-QPSK) transmission. The results depict that RRC pulses are more tolerant to intra-channel non-linearities, i.e. self-phase modulation (SPM), as compared to standard RZ-33 and NRZ pulses. The non-linear threshold point is improved by using RRC pulses by a factor of 2 dB signal input power as compared to RZ pulses and by 4 dB signal launch power as compared to NRZ pulses. The behavior of RRC pulses is also investigated with standard single mode fiber (SMF), non-zero dispersion shifted fiber (NZDSF) and next-generation large Aeff pure silica core fiber (LA-PSCF). Most importantly multi-span DBP is implemented and in the case of RRC pulses the computational efforts of the conventional DBP algorithm are reduced by 80% with a diminutive Q-penalty of 0.74 dB. The duty cycle of the RRC pulses is further optimized for efficient system performance. We have also compared the performance of single-channel transmission with the multi-channel transmission, where the performance is limited due to inter-channel non-linear effects. Furthermore, the non-linear tolerance of RRC pulses is investigated with; (a) different amplifier spacing and (b) variation in transmission link design information for the DBP algorithm.

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

    SciTech Connect

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

    1999-04-04

    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.

  6. Motion Compensation on DCT Domain

    NASA Astrophysics Data System (ADS)

    Koc, Ut-Va; Liu, K. J. Ray

    2001-12-01

    Alternative fully DCT-based video codec architectures have been proposed in the past to address the shortcomings of the conventional hybrid motion compensated DCT video codec structures traditionally chosen as the basis of implementation of standard-compliant codecs. However, no prior effort has been made to ensure interoperability of these two drastically different architectures so that fully DCT-based video codecs are fully compatible with the existing video coding standards. In this paper, we establish the criteria for matching conventional codecs with fully DCT-based codecs. We find that the key to this interoperability lies in the heart of the implementation of motion compensation modules performed in the spatial and transform domains at both the encoder and the decoder. Specifically, if the spatial-domain motion compensation is compatiable with the transform-domain motion compensation, then the states in both the coder and the decoder will keep track of each other even after a long series of P-frames. Otherwise, the states will diverge in proportion to the number of P-frames between two I-frames. This sets an important criterion for the development of any DCT-based motion compensation schemes. We also discuss and develop some DCT-based motion compensation schemes as important building blocks of fully DCT-based codecs. For the case of subpixel motion compensation, DCT-based approaches allow more accurate interpolation without any increase in computation. Furthermore, a scare number of DCT coefficients after quantization significantly decreases the number of calculations required for motion compensation. Coupled with the DCT-based motion estimation algorithms, it is possible to realize fully DCT-based codecs to overcome the disadvantages of conventional hybrid codecs.

  7. Using spatially-variable wind fields derived from GPS zenith wet delay timeseries to compensate atmospheric phase signatures in SAR interferograms

    NASA Astrophysics Data System (ADS)

    Onn, F.; Zebker, H. A.

    2005-12-01

    Fluctuations in the distribution of water vapor near the surface of the earth causes variations in neutral atmospheric refractive index. These fluctuations appear as excess delays in Global Positioning System (GPS) signals and as phase shifts in Interferometric Synthetic Aperture Radar (InSAR) images. Because the neutral atmospheric medium affects the propagation of GPS and SAR signals in comparable ways, we use timeseries of observations of zenith wet delay (ZWD) from a network of continuous GPS stations operating in the area imaged by a spaceborne SAR to correct atmospheric phase signatures observed in a radar interferogram of the study area. We interpolate spatial samples of GPS ZWD to derive maps of atmospheric delay which we subtract from the observed atmospheric phase in the SAR interferogram. We interpolate ZWD samples recorded in a virtual network of GPS data generated by applying Taylor's ``frozen-flow'' hypothesis to ZWD measurements recorded before and after the SAR acquisition instances. The ``frozen-flow'' hypothesis is used in a stochastic transport model for integrated refractivity fields, which assumes that the observed timeseries of ZWD at a fixed GPS site consists of a superposition of ``frozen-in'' refractivity fields moving across the study area under the action of a slowly-varying mean wind field. The measured relative time delays between pairs of ZWD timeseries permit calculation of the wind field as a function of time. These spatially-variable wind field estimates are then used to translate GPS ZWD measurements observed before and after the radar acquisition times to equivalent spatial samples on the grid of the radar interferogram. Thus, we infer a denser distribution of ZWD samples from GPS than is possible by considering GPS delay measurements acquired only at the SAR observation times. We find that the atmospheric delay map generated by interpolation of the virtual network of GPS ZWD observations results in lower rms error than the corresponding map generated from GPS data recorded only at the satellite SAR times. We compare the resulting spatial disribution of GPS ZWD samples with colocated observations InSAR differential to verify our estimates of wind fields. We also compare our estimates of wind with in situ measurements of surface layer wind obtained from National Weather Service (NWS) meteorological stations operating in the study area.

  8. Video compression by coefficient compensation

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hirohisa

    1994-05-01

    This paper discusses a new video compression algorithm called Coefficient Compensation that achieves high performance by optimizing the DCT encoding loop structure, and demonstrates its improvement characteristic as compared with the conventional JPEG or MPEG I/P picture encoding under the condition that movement compensation is not available. The first part of the paper analyzes the performance of the DCT encoding loop structure, the method of optimization and the concept of soft-decision. The second part reports on the simulation results. Encoding performance is tested by various MPEG test sequences compressed in 20 Mbits/sec. The difference between JPEG and MPEG I is in the quantization table. For JPEG, the quantization table widely accepted as one producing a good compression quality is used. All the encoded binary outputs are fully compatible to the MPEG2 syntax but additional 2 bits/block information is coded as the user data for the Coefficient Compensation.

  9. SAR motion compensation using autofocus

    NASA Astrophysics Data System (ADS)

    Blacknell, D.; Quegan, S.

    1991-02-01

    Conventional motion compensation schemes correct for unwanted synthetic aperture radar (SAR) platform motions using information from an inertial measurement unit (IMU). Autofocus techniques, which focus SAR images, produce an 'autofocus parameter' which is related to the platform motion. In this paper, strong evidence is presented to support the assumption that the contrast optimization autofocus algorithm behaves as a least-squares quadratic fitting to the SAR platform trajectory. Using this assumption, the relationship between the autofocus parameter and across-track accelerations of the SAR platform is derived. This allows the SAR platform motion to be estimated from the autofocus parameter measurements and incorporated in a motion compensation instead of IMU measurements. Three implementations of motion compensation using autofocus are compared and the achievable image quality is quantified.

  10. 50 CFR 600.245 - Council member compensation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Council member compensation. 600.245... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MAGNUSON-STEVENS ACT PROVISIONS Council Membership 600.245 Council member compensation. (a) All voting Council members whose eligibility for compensation...

  11. 50 CFR 600.245 - Council member compensation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Council member compensation. 600.245... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MAGNUSON-STEVENS ACT PROVISIONS Council Membership 600.245 Council member compensation. (a) All voting Council members whose eligibility for compensation...

  12. 50 CFR 600.245 - Council member compensation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Council member compensation. 600.245... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MAGNUSON-STEVENS ACT PROVISIONS Council Membership 600.245 Council member compensation. (a) All voting Council members whose eligibility for compensation...

  13. Construction of an Eulerian atmospheric dispersion model based on the advection algorithm of M. Galperin: dynamic cores v.4 and 5 of SILAM v.5.5

    NASA Astrophysics Data System (ADS)

    Sofiev, M.; Vira, J.; Kouznetsov, R.; Prank, M.; Soares, J.; Genikhovich, E.

    2015-03-01

    The paper presents dynamic cores v.4 and v.5 of the System for Integrated modeLling of Atmospheric coMposition SILAM v.5.5 based on the advection algorithm of Michael Galperin. This advection routine, so far weakly presented in international literature, is non-diffusive, positively defined, stable with regard to Courant number significantly above one, and very efficient computationally. For the first time, we present a rigorous description of its original version, along with several updates that improve its monotonicity and allow applications to long-living species in conditions of complex atmospheric flows. The other extension allows the scheme application to dynamics of aerosol spectra. The scheme is accompanied with the previously developed vertical diffusion algorithm, which encapsulates the dry deposition process as a boundary condition. Connection to chemical transformation modules is outlined, accounting for the specifics of transport scheme. Quality of the advection routine is evaluated using a large set of tests. The original approach has been previously compared with several classic algorithms widely used in operational models. The basic tests were repeated for the updated scheme, along with demanding global 2-D tests recently suggested in literature, which allowed positioning the scheme with regard to sophisticated state-of-the-art approaches. The model performance appeared close to the top of the list with very modest computational costs.

  14. A mathematical model, algorithm, and package of programs for simulation and prompt estimation of the atmospheric dispersion of radioactive pollutants

    SciTech Connect

    Nikolaev, V.I.; Yatsko, S.N.

    1995-12-01

    A mathematical model and a package of programs are presented for simulating the atmospheric turbulent diffusion of contaminating impurities from land based and other sources. Test calculations and investigations of the effect of various factors are carried out.

  15. RECIPES FOR WRITING ALGORITHMS FOR ATMOSPHERIC CORRECTIONS AND TEMPERATURE/EMISSIVITY SEPARATIONS IN THE THERMAL REGIME FOR A MULTI-SPECTRAL SENSOR

    SciTech Connect

    C. BOREL; W. CLODIUS

    2001-04-01

    This paper discusses the algorithms created for the Multi-spectral Thermal Imager (MTI) to retrieve temperatures and emissivities. Recipes to create the physics based water temperature retrieval, emissivity of water surfaces are described. A simple radiative transfer model for multi-spectral sensors is developed. A method to create look-up-tables and the criterion of finding the optimum water temperature are covered. Practical aspects such as conversion from band-averaged radiances to brightness temperatures and effects of variations in the spectral response on the atmospheric transmission are discussed. A recipe for a temperature/emissivity separation algorithm when water surfaces are present is given. Results of retrievals of skin water temperatures are compared with in-situ measurements of the bulk water temperature at two locations are shown.

  16. Faculty Compensation Policies.

    ERIC Educational Resources Information Center

    Silander, Fred

    1983-01-01

    Faculty compensation policy is seen as one means by which an institution influences the faculty to work toward institutional goals. Among the broad criteria for compensation are worth, equity, need, and market measures. Benefits and issues in compensation including differentials in compensation, merit, part-time instruction, etc. are discussed.…

  17. Reactive power compensating system

    DOEpatents

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

    1987-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Mariano, Adrian V.; Grossmann, John M.

    2010-11-01

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

  19. The theory of compensated laser propagation through strong thermal blooming

    NASA Astrophysics Data System (ADS)

    Schonfeld, Jonathan F.

    An account is given of the theory of adaptive compensation for a laser beam's thermal blooming in atmospheric transmission, giving attention to MOLLY, a highly realistic computer simulation of adaptively compensated laser propagation which illustrates the effects of atmospheric turbulence and thermal blooming. Robust experimental signatures have been developed for such important fundamental processes as phase-compensation instability (PCI), which is caused by positive feedback between an adaptive optics system and laser-induced atmospheric heating. The physics of uncompensated and compensated thermal blooming is discussed, in conjunction with the architecture of MOLLY and an analysis of PCI that takes detailed adaptive-optics hardware structures into account.

  20. 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)

    Dieriam, Todd A.

    1990-01-01

    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.

  1. Compensator improvement for multivariable control systems

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Herring, Thomas A.; Quinn, Katherine J.

    2012-01-01

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

  3. Compensation Review Analyst

    Energy Science and Technology Software Center (ESTSC)

    2003-06-03

    COMPERA is a decision support system designed to facilitate the compensation review process. With parameters provided by the user(s), the system generates recommendations for base increases and nonbase compensation that strives to align total compensation with performance compensation targets. The user(s) prescribe(s) compensation targets according to performance (or value of contribution) designators. These targets are presented in look-up tables, which are then used by embedded formulas in the worksheet to determine the recommended compensation formore » each individual.« less

  4. Saliency driven Black Point Compensation

    NASA Astrophysics Data System (ADS)

    Lindner, Albrecht; Bonnier, Nicolas; Ssstrunk, Sabine

    2011-01-01

    We present a novel framework for automatically determining whether or not to apply black point compensation (BPC) in image reproduction. Visually salient objects have a larger influence on determining image quality than the number of dark pixels in an image, and thus should drive the use of BPC. We propose a simple and efficient algorithmic implementation to determine when to apply BPC based on low-level saliency estimation. We evaluate our algorithm with a psychophysical experiment on an image data set printed with or without BPC on a Canon printer. We find that our algorithm is correctly able to predict the observers' preferences in all cases when the saliency maps are unambiguous and accurate.

  5. An active Z gravity compensation system

    NASA Astrophysics Data System (ADS)

    White, Greg; Xu, Yangsheng

    1992-07-01

    To perform simulations of partial or microgravity environments on earth requires some method of compensation for the earth's gravitational field. This paper discusses an active compensation system that modulates the tension in a counterweight support cable in order to minimize state deviation between the compensated body and the ideal weightless body. The system effectively compensates for inertial effects of the counterweight mass, viscous damping of all pulleys, and static friction in all parts of the GC system using a hybrid PI/fuzzy control algorithm. The dynamic compensation of inertia and viscous damping is performed by PI control, while static friction compensation is performed by the fuzzy system. The system provides very precise gravity compensation force, and is capable of non-constant gravity force compensation in the case that the payload mass is not constant. The only additional hardware requirements needed for the implementation of this system on a passive counterweight balance system are: a strain gauge tension sensor, and a torque motor with encoder.

  6. 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)

    1995-01-01

    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.

  7. Reconstruction of image sequences using motion compensation

    NASA Astrophysics Data System (ADS)

    Yang, Yongyi; Gravier, Erwan J.

    2004-05-01

    In this paper we study a motion-compensated approach for simultaneous reconstruction of image frames in a time sequence. We treat the frames in a sequence collectively as a single function of both space and time, and define a temporal prior to account for the temporal correlations in a sequence. This temporal prior is defined in a form of motion-compensation, aimed to follow the curved trajectories of the object motion through space-time. The image frames are then obtained through estimation using the expectation-maximization (EM) algorithm. The proposed algorithm was evaluated extensively using the 4D gated mathematical cardiac-torso (gMCAT) D1.01 phantom to simulate gated SPECT perfusion imaging with Tc99m. Our experimental results demonstrate that the use of motion compensation for reconstruction can lead to significant improvement in image quality and reconstruction accuracy.

  8. [Data analysis of laser desorption/ionization mass spectrum of atmospheric aerosol particles using fuzzy clustering algorithms].

    PubMed

    Guo, Xiao-yong; Fang, Li; Zhao, Wen-wu; Gu, Xue-jun; Zheng, Hai-yang; Zhang, Wei-jun

    2008-08-01

    On-line measurement of size and composition of single particle using an aerosol time-of-flight Laser mass spectrometry (ATOFLMS) had been designed in our lab. Each particle's aerodynamic diameter is determined by measuring the delay time between two continuous-wave lasers, A Nd : YAG laser desorbs and ionizes molecules from the particle, and the time-of-flight mass spectrometer collects a mass spectrum of the generated ions. Then the composition of single particle is obtained. ATOFLMS generates large amount of data during the process period. How to process these data and extract valuable information is one of the key problems for the ATOFLMS. In this paper, the fuzzy clustering used to classify large numbers of mass spectral of air indoor by an ATOFLMS. Each revised spectrum is converted to a normalized 300-point vector, each point representing one mass unit. Then the positive ion mass spectra of a single particle are described as 300-dimensional data vectors using the ion masses as dimensions and the ion signal peak areas as values. The data vectors of all particles measured are written into a classification matrix. Each spectrum's data was stored as one row in this matrix. The Fuzzy c-means algorithm is an iterative method starting the calculation with random class centers to find a substructure in the data. The procedure works in such a way that finally similar objects (particle spectra) have a minimum distance between their corresponding data vectors, on the one hand, and to the center of a cluster, on the other hand. So the aim of the iteration is to find local minima in the N-dimensional space where N is the number of evaluated peak masses. The particle data used in this study were collected over a period one day in Hefei. During the campaign, inorganic salts, mineral particles, and carbonaceous particles, with varying degrees of secondary components, were identified. The detection results of particle size exhibit that aerosol is predominanantly in the form of fine particles, and the particles whose diameter larger than 1 microm are scare. The particles whose diameter less than 1 microm are make up of 95% of the total particles, and these particles are major distributed in 0.4-0.8 microm. PMID:18975786

  9. Loss-compensated radiometer

    SciTech Connect

    Lobo, P.C.

    1984-05-01

    A new radiometer concept is described and evaluated. Automatic dynamic electrical compensation is achieved by a high-gain feedback amplifier and low thermal inertia solar and compensating electrical sensors. With sufficiently high gain, compensation can increase accuracy to limits determined by amplifier drift. Equations governing instrument response are derived and analyzed. Initial measurements on a preliminary prototype confirm the validity of the concept which should yield a very accurate instrument with ''self calibrating'' features.

  10. Compensator configurations for load currents' symmetrization

    NASA Astrophysics Data System (ADS)

    Rusinaru, D.; Manescu, L. G.; Dinu, R. C.

    2016-02-01

    This paper approaches aspects regarding the mitigation effects of asymmetries in 3-phase 3-wire networks. The measure consisting in connecting of load current symmetrization devices at the load coupling point is presented. A time-variation of compensators parameters is determined as a function of the time-recorded electrical values. The general sizing principle of the load current symmetrization reactive components is based on a simple equivalent model of the unbalanced 3-phase loads. By using these compensators a certain control of the power components transits is ensured in the network. The control is based on the variations laws of the compensators parameters as functions of the recorded electrical values: [B] = [T]·[M]. The link between compensator parameters and measured values is ensured by a transformation matrix [T] for each operation conditions of the supply network. Additional conditions for improving of energy and efficiency performance of the compensator are considered: i.e. reactive power compensation. The compensator sizing algorithm was implemented into a MATLAB environment software, which generate the time-evolution of the parameters of load current symmetrization device. The input data of application takes into account time-recording of the electrical values. By using the compensator sizing software, some results were achieved for the case of a consumer connected at 20 kV busbar of a distribution substation, during 24 hours measurement session. Even the sizing of the compensators aimed some additional network operation aspects (power factor correction) correlated with the total or major load symmetrizations, the harmonics aspects of the network values were neglected.

  11. Algorithms and Algorithmic Languages.

    ERIC Educational Resources Information Center

    Veselov, V. M.; Koprov, V. M.

    This paper is intended as an introduction to a number of problems connected with the description of algorithms and algorithmic languages, particularly the syntaxes and semantics of algorithmic languages. The terms "letter, word, alphabet" are defined and described. The concept of the algorithm is defined and the relation between the algorithm and

  12. Gmti Motion Compensation

    DOEpatents

    Doerry, Armin W.

    2004-07-20

    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.

  13. Ecology: compensating for extinction.

    PubMed

    Kareiva, Peter

    2004-08-10

    Food web interactions allow communities to compensate for the loss of species. Compensation of this kind may reshuffle communities so that today's resilient species are tomorrow's vulnerable species, creating a false impression of ecosystem stability following the first wave of extinction. PMID:15296781

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    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.

  15. Compensation of distributed delays in integrated communication and control systems

    NASA Technical Reports Server (NTRS)

    Ray, Asok; Luck, Rogelio

    1991-01-01

    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.

  16. PMD compensation techniques

    NASA Astrophysics Data System (ADS)

    Blow, Henning; Lanne, Stphanie

    Mitigating PMD is still a challenge in today's optical communications. After giving the key performance indicators dictated by the statistical nature of PMD, we introduce the classification of PMD compensation schemes into 2 categories: optical and electrical PMD compensators. In a first part, we explain the operation principle of a PMD compensator by taking a detailed look at the basic optical PMD compensator and appropriate feedback signals. More complex multistage structures and a feed-forward adaptation approach are also discussed. This first part is closed by results from a one-year field trial confirming the behavior and performance of a prototype compensator. In the second part of this article, electronic equalization for PMD mitigation is explained. Starting with a discussion on performance and adaptation of linear equalizers suitable for analog electronic signal processing, finally also the Viterbi equalizer basing on digital signal processing is analyzed. A comparative review of mitigation by optical or electronic means concludes the discussion.

  17. Adaptive motion compensation without blocking artifacts

    NASA Astrophysics Data System (ADS)

    Terriberry, Timothy B.

    2015-03-01

    The Block Matching Algorithms used in most popular video codec standards introduce blocking artifacts which must be removed via residual coding or deblocking filters. Alternative transform stages that do not cause blocking artifacts, such as lapped transforms or wavelets, require motion compensation methods that do not produce blocking artifacts, since they are expensive to remove. We design a new Overlapped Block Motion Compensation (OBMC) scheme that avoids these artifacts while allowing adaptive blending window sizes. This has the potential to show significant visual quality improvements over traditional OBMC.

  18. Subsurface Xenon Migration by Atmospheric Pumping Using an Implicit Non-Iterative Algorithm for a Locally 1D Dual-Porosity Model

    NASA Astrophysics Data System (ADS)

    Annewandter, R.; Kalinowksi, M. B.

    2009-04-01

    An underground nuclear explosion injects radionuclids in the surrounding host rock creating an initial radionuclid distribution. In the case of fractured permeable media, cyclical changes in atmospheric pressure can draw gaseous species upwards to the surface, establishing a ratcheting pump effect. The resulting advective transport is orders of magnitude more significant than transport by molecular diffusion. In the 1990s the US Department of Energy funded the socalled Non-Proliferation Experiment conducted by the Lawrence Livermore National Laboratory to investigate this barometric pumping effect for verifying compliance with respect to the Comprehensive Nuclear Test Ban Treaty. A chemical explosive of approximately 1 kt TNT-equivalent has been detonated in a cavity located 390 m deep in the Rainier Mesa (Nevada Test Site) in which two tracer gases were emplaced. Within this experiment SF6 was first detected in soil gas samples taken near fault zones after 50 days and 3He after 325 days. For this paper a locally one-dimensional dual-porosity model for flow along the fracture and within the permeable matrix was used after Nilson and Lie (1990). Seepage of gases and diffusion of tracers between fracture and matrix are accounted. The advective flow along the fracture and within the matrix block is based on the FRAM filtering remedy and methodology of Chapman. The resulting system of equations is solved by an implicit non-iterative algorithm. Results on time of arrival and subsurface concentration levels for the CTBT-relevant xenons will be presented.

  19. A Novel Algorithm Applied to Common Thermal-Optical Transmission Data for Determining Mass Absorption Cross Sections of Atmospheric Black Carbon: Applications to the Indian Outflow

    NASA Astrophysics Data System (ADS)

    Andersson, A.; Sheesley, R. J.; Kirillova, E.; Gustafsson, O.

    2010-12-01

    High wintertime concentrations of black carbon aerosols (BCA) over South Asia and the Northern Indian Ocean are thought to have a large impact on the regional climate. Direct absorption of sunlight by BCAs causes heating of the atmosphere and cooling at the surface. To quantify such effects it is important to characterize a number of different properties of the aerosols. Here we present a novel application of the thermal-optical (OCEC) instrument in which the laser beam is used to obtain optical information about the aerosols. In particular, the novel algorithm accounts for non-carbon contributions to the light extinction. Combining these light extinction coefficients with the simultaneously constrained Elemental Carbon (EC) concentrations, the Mass Absorption Cross Section (MAC) is computed. Samples were collected during a continuous 14-month campaign Dec 2008 - Mar 2009 at Sinaghad in Western India and on Hanimaadhoo, the Northernmost Island in the Maldives. This data set suggests that the MAC of the BCAs are variable, sometimes by a factor of 3 compared to the mean. This observation adds to the complexity of calculating the radiative forcing for BCAs, reinforcing previous observations that parameters such as aerosol mixing state and sources need to be taken into account.

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

    NASA Astrophysics Data System (ADS)

    Broda, Krzysztof; Filipek, Wiktor

    2013-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  3. Reactive Power Compensator.

    DOEpatents

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

    1992-07-28

    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.

  4. Reactive power compensator

    DOEpatents

    El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.; Chen, Mingliang; Andexler, George; Huang, Tony

    1992-01-01

    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.

  5. Temperature Effects and Compensation-Control Methods

    PubMed Central

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

    2009-01-01

    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

  6. Seismic attenuation compensation by Bayesian inversion

    NASA Astrophysics Data System (ADS)

    Wang, Shoudong; Song, Huijuan; Yang, Dengfeng

    2014-12-01

    As an effective method to improve seismic data resolution, attenuation compensation has been paid great attention. The popular method inverse Q-filter performs effectively in phase correction. But its energy compensation part is at an extraordinary discount because of its instability. By contrast, the compensation method based on inversion has a great advantage in algorithm stability. In this paper, the inversion process is combined with Bayesian principle so that the prior information we learned about the actual model can be used sufficiently. Here, we have an assumption that it is more reasonable to describe the reflectivities with sparse distribution. This information, in general, can be transferred to a sparse constraint of the object function. And compared with Tikhonov regularization method, it is proved to perform better in seismic resolution improvement. Meanwhile, it is insensitive to the error of Q value. Example of real data shows the validity of the method.

  7. Delay compensation in integrated communication and control systems. II - Implementation and verification

    NASA Technical Reports Server (NTRS)

    Luck, Rogelio; Ray, Asok

    1990-01-01

    The implementation and verification of the delay-compensation algorithm are addressed. The delay compensator has been experimentally verified at an IEEE 802.4 network testbed for velocity control of a DC servomotor. The performance of the delay-compensation algorithm was also examined by combined discrete-event and continuous-time simulation of the flight control system of an advanced aircraft that uses the SAE (Society of Automotive Engineers) linear token passing bus for data communications.

  8. An innovative approach to compensator design

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    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.

  9. Nonlinear compensation technologies for future optical communication systems

    NASA Astrophysics Data System (ADS)

    Oyama, Tomofumi; Hoshida, Takeshi; Nakashima, Hisao; Oda, Shoichiro; Yamauchi, Tomohiro; Tanimura, Takahito; Dou, Liang; Zhao, Ying; Tao, Zhenning; Rasmussen, Jens C.

    2015-01-01

    Digital nonlinear compensation techniques have been thought to be keys to realize further spectrally efficient optical fiber communication systems. The most critical issue of the digital nonlinear compensation algorithms has been their computational complexity, or gate count of digital signal processing circuit. Among several approaches, digital nonlinear compensation algorithms based on perturbation analysis are attractive in terms of the hardware efficiency because the algorithms can compensate the accumulated nonlinear noise over all transmission spans with only one stage. In this paper, we discuss three approaches to sophisticate the perturbation nonlinear compensation. First, we illustrate a perturbation-based post-equalization method to improve the robustness to transceiver device imperfections. We next propose and numerically evaluate a symbol degeneration method to extend the perturbation nonlinear compensation methods to higher-order QAM without increasing the computational complexity. Finally, we discuss a sub-band processing of perturbation nonlinear compensation for further computational complexity reduction. By combining the perturbation method with Nyquist frequency division multiplexing, the computational complexity of perturbation calculation is reduced by a factor of more than 10 for 3000-km single-channel transmission of 128 Gbit/s dualpolarization QPSK with only 0.1 dB performance degradation.

  10. The compensated Kalman filter.

    NASA Technical Reports Server (NTRS)

    Athans, M.

    1972-01-01

    This paper introduces the compensated Kalman filter, a suboptimal state estimator which can be used to eliminate steady-state bias errors when it is used in conjunction with the mismatched steady-state (asymptotic) time-invariant Kalman-Bucy filter. The uncompensated mismatched steady state Kalman-Bucy filter exhibits bias errors whenever the nominal plant parameters used in the filter design are different from the actual plant parameters. The approach used relies on the utilization of the residual (innovations) process of the mismatched filter to estimate, via a Kalman-Bucy filter, the state estimation errors and subsequent improvements of the state estimate. The compensated Kalman filter augments the mismatched steady state Kalman-Bucy filrby the introduction of additional dynamics and feedforward integral compensation channels.

  11. Compensation of printer MTFs

    NASA Astrophysics Data System (ADS)

    Bonnier, Nicolas; Lindner, Albrecht J.; Leynadier, Christophe; Schmitt, Francis

    2009-01-01

    Premilary experiments have shown that the quality of printed images depends on the capacity of the printing system to accurately reproduce details.1 We propose to improve the quality of printed images by compensating for the Modulation Transfer Function (MTF) of the printing system. The MTF of the printing system is measured using the method proposed by Jang and Allebach,2 in which test pages consisting of series of patches with different 1D sinusoidal modulations (modified to improve the accuracy of the results3) are printed, scanned and analyzed. Then the MTF is adaptively compensated in the Fourier domain, depending both on frequency and local mean values. Results of a category judgment experiment show significant improvement as the printed MTF compensated images obtain the best scores.

  12. Thermal compensating mount

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  13. Adaptive PMD compensation up to second-order in 40Gb/s OTDM optical communication system using two-stage compensator

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoguang; Xi, Lixia; Yu, Li; Zhou, Guangtao; Zhang, Jianzhong; Zhang, Na; Wu, Bin; Yuan, Tiecheng; Chen, Lin; Zhang, Hongming; Yao, Minyu; Yang, Bojun

    2005-02-01

    In this paper we report a successful experiment of adaptive polarization mode dispersion (PMD) compensation up to second-order in a 40Gb/s optical time-division multiplexed (OTDM) communication system by using two-stage compensator. In the experiment the PMD monitoring technique based on degree of polarization (DOP) was adopted. And the Particle Swarm Optimization (PSO) algorithm was introduced in adaptive PMD compensation, with the desirable features of fast convergence to the global optimum point for compensation without being trapped in local sub-optima and with good robustness to noise. The comparison was made to estimate the performance effectiveness between PSO algorithms with global neighborhood structure (GPSO) and with local neighborhood structure (LPSO). The LPSO algorithm is shown to be more effective to search global optimum for PMD compensation than GPSO algorithm. The ability of tracking changed PMD using PSO algorithm was also investigated. The two-stage PMD compensator is shown to be effective for both first- and second-order PMD, and the compensator is shown to be bit rate independent. The compensation time is within several hundreds of milliseconds. The response time for recovery from a sharp disturbance is about 11ms.

  14. Wavefront compensation with pseudoconjugation

    NASA Astrophysics Data System (ADS)

    Omeara, T. R.

    1982-04-01

    It is shown how novel arrangements of conventional (static/linear) optical elements can compensate for many classes of time-varying phase distortions in optical trains. Precision corner arrays, lens arrays, and K-mirror arrays are all applicable as pseudoconjugation elements in certain classes of problems. In some cases, multipassing (four or more passes) of a distorting medium can offer improved performance. Although the compensation is more limited than that available from nonlinear optical phase conjugation, problems associated with thresholds, pumps, and frequency translations are eliminated.

  15. Hysteresis compensation for a piezoelectric fiber optic voltage sensor

    NASA Astrophysics Data System (ADS)

    Fusiek, G.; Niewczas, Pawel; Dziuda, L.; McDonald, James R.

    2005-11-01

    We present details of numerical techniques developed to compensate the effects of hysteresis experienced by a hybrid piezoelectric fiber optic voltage sensor. The techniques, implemented using a real-time signal processing system, are tested and their effectiveness evaluated experimentally. The best of the proposed algorithms provides phase error compensation from approximately 7 to nearly 0 deg, and allows us to perform sensor calibration to achieve accuracy better than 0.5% (full scale output).

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

    SciTech Connect

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

    2013-09-11

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

  17. Reactive Power Compensating System.

    DOEpatents

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

    1985-01-04

    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.

  18. The Compensation Question

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  19. The Compensation Question

    ERIC Educational Resources Information Center

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

    2012-01-01

    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

  20. Formula Based Compensation.

    ERIC Educational Resources Information Center

    Sears, Doug; Picus, Lawrence O.

    1999-01-01

    Recognizing that traditional salary bargaining is divisive and that teacher salaries should remain competitive, Temple City (California) Unified School District has been experimenting with formula-based compensation for the past four years. Primary benefits are lack of conflict over salary increases, which are determined before negotiating other

  1. Teacher Compensation and Organization.

    ERIC Educational Resources Information Center

    Kelley, Carolyn

    Traditionally, teacher compensation has been viewed in isolation from other components of organizational reform. This paper examines changes in dominant models of schooling over time using an organizational lens. The six models include scientific management, humanistic/specialization, effective schools, content-driven, high standards/high

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  3. Two-stage adaptive PMD compensation in 40-Gb/s OTDM optical communication system

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoguang; Xi, Lixia; Yu, Li; Zhou, Guangtao; Zhang, Jianzhong; Zhang, Na; Wu, Bin; Yuan, Tiecheng; Chen, Lin; Zhang, Hongming; Chen, Shuo; Yao, Minyu; Yang, Bojun

    2004-06-01

    An experiment of two-stage adaptive compensation for polarization mode dispersion (PMD) in a 40-Gb/s optical time-division multiplexed communication system is reported. The PMD monitoring technique based on degree of polarization was adopted. The particle swarm optimization (PSO) algorithm was introduced in adaptive PMD compensation. The comparison was made to estimate the effectiveness between PSO algorithms with global neighborhood structure (GPSO) and with local neighborhood structure (LPSO). The LPSO algorithm is shown to be more effective to search global optimum for PMD compensation than GPSO algorithm. The two-stage PMD compensator is shown to be effective for both first- and second-order PMD, and the compensator is shown to be bit rate independent. The optimum searching time is within one hundred milliseconds.

  4. An innovative approach to compensator design

    NASA Technical Reports Server (NTRS)

    Mitchell, J. R.

    1972-01-01

    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).

  5. Enhanced motion estimation algorithm with prefiltering in video compression

    NASA Astrophysics Data System (ADS)

    Jang, Jinik; Lee, Hyuk; Hong, Sun-Min; Jeong, Jechang

    2012-03-01

    We present an enhanced motion estimation and compensation algorithm by prefiltering reference frames before motion estimation. The conventional block based motion estimation algorithm gives poor performance when abrupt motion change occurs. The proposed algorithm constructs prefilters based on motion vector distribution analysis and compensates temporal sampling artifacts, such as blur or deblur, between adjacent frames. Compared to H.264/AVC, the proposed algorithm achieves significant bit-rate reduction up to 14.59%.

  6. Deferred Compensation Becomes More Common

    ERIC Educational Resources Information Center

    June, Audrey Williams

    2006-01-01

    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

  7. Ground difference compensating system

    DOEpatents

    Johnson, Kris W.; Akasam, Sivaprasad

    2005-10-25

    A method of ground level compensation includes measuring a voltage of at least one signal with respect to a primary ground potential and measuring, with respect to the primary ground potential, a voltage level associated with a secondary ground potential. A difference between the voltage level associated with the secondary ground potential and an expected value is calculated. The measured voltage of the at least one signal is adjusted by an amount corresponding to the calculated difference.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

  9. Control optimization, stabilization and computer algorithms for aircraft applications

    NASA Technical Reports Server (NTRS)

    1975-01-01

    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.

  10. Software compensated multichannel pressure sensing system

    NASA Technical Reports Server (NTRS)

    Chapman, John J.

    1990-01-01

    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.

  11. SOFIA image motion compensation

    NASA Astrophysics Data System (ADS)

    Dunham, Edward; Collins, Peter; Reinacher, Andreas; Lampater, Ulrich

    2010-07-01

    We describe a laboratory simulation of an image motion compensation system for SOFIA that uses high-speed image acquisition from the science instrument HIPO as the sensing element of the system and a Newport voice-coil actuated fast steering mirror as the correcting actuator. Performance of the system when coupled to the SOFIA secondary mirror is estimated based on the known current performance of the secondary mirror controller. The system is described and the observed performance is presented together with expectations for applicability in flight with SOFIA.

  12. Analysis and modeling of thermal-blooming compensation

    NASA Astrophysics Data System (ADS)

    Schonfeld, Jonathan F.

    1990-05-01

    The present evaluation of recent progress in the analysis and computer modeling of adaptive optics hardware applicable to compensation for thermal blooming gives attention to an analytical theory of phase-compensation instability (PCI) that incorporates the actuator geometry of real deformable mirrors, as well as to novel algorithms for computer simulation of adaptive optics hardware. An analytical formalism is presented which facilitates the quantitative analysis of the effects of the adaptive-optics control system on PCI, and leads to both a universality theorem for PCI growth rates and the realization that wind exerts a greater influence on PCI growth rates than previously suspected. The analysis and algorithms are illustrated by the results of the time-dependent adaptively-compensated laser propagation code for thermal blooming, MOLLY, which has been optimized for the Cray-2 supercomputer.

  13. Block-classified motion compensation scheme for digital video

    SciTech Connect

    Zafar, S.; Zhang, Ya-Qin; Jabbari, B.

    1996-03-01

    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.

  14. Complexity-reduced digital nonlinear compensation for coherent optical system

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  15. Computer aided modelling/compensator design for a flexible space antenna

    NASA Technical Reports Server (NTRS)

    Gibson, J. S.; Mingori, D. L.

    1985-01-01

    Controller design algorithms are developed to produce simultaneously both a model of the plant and a compensator. The size of the model and properties of the compensator are driven by the performance requirements, the disturbance environment, and the location, number and type of sensors and actuators. The procedure is based on linear optimal control theory for distributed systems, and balanced realization theory is used to guide the development of the model and reduce the order of the compensator.

  16. Using Weighting Adjustments to Compensate for Survey Nonresponse

    ERIC Educational Resources Information Center

    Pike, Gary R.

    2008-01-01

    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…

  17. Using Weighting Adjustments to Compensate for Survey Nonresponse

    ERIC Educational Resources Information Center

    Pike, Gary R.

    2008-01-01

    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

  18. Springback Prediction, Compensation and Correlation for Automotive Stamping

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

    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.

  19. Springback Prediction, Compensation and Correlation for Automotive Stamping

    SciTech Connect

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

    2005-08-05

    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.

  20. A Novel Speed Compensation Method for ISAR Imaging with Low SNR

    PubMed Central

    Liu, Yongxiang; Zhang, Shuanghui; Zhu, Dekang; Li, Xiang

    2015-01-01

    In this paper, two novel speed compensation algorithms for ISAR imaging under a low signal-to-noise ratio (SNR) condition have been proposed, which are based on the cubic phase function (CPF) and the integrated cubic phase function (ICPF), respectively. These two algorithms can estimate the speed of the target from the wideband radar echo directly, which breaks the limitation of speed measuring in a radar system. With the utilization of non-coherent accumulation, the ICPF-based speed compensation algorithm is robust to noise and can meet the requirement of speed compensation for ISAR imaging under a low SNR condition. Moreover, a fast searching implementation strategy, which consists of coarse search and precise search, has been introduced to decrease the computational burden of speed compensation based on CPF and ICPF. Experimental results based on radar data validate the effectiveness of the proposed algorithms. PMID:26225980

  1. A Novel Speed Compensation Method for ISAR Imaging with Low SNR.

    PubMed

    Liu, Yongxiang; Zhang, Shuanghui; Zhu, Dekang; Li, Xiang

    2015-01-01

    In this paper, two novel speed compensation algorithms for ISAR imaging under a low signal-to-noise ratio (SNR) condition have been proposed, which are based on the cubic phase function (CPF) and the integrated cubic phase function (ICPF), respectively. These two algorithms can estimate the speed of the target from the wideband radar echo directly, which breaks the limitation of speed measuring in a radar system. With the utilization of non-coherent accumulation, the ICPF-based speed compensation algorithm is robust to noise and can meet the requirement of speed compensation for ISAR imaging under a low SNR condition. Moreover, a fast searching implementation strategy, which consists of coarse search and precise search, has been introduced to decrease the computational burden of speed compensation based on CPF and ICPF. Experimental results based on radar data validate the effectiveness of the proposed algorithms. PMID:26225980

  2. Self-compensating tensiometer and method

    DOEpatents

    Hubbell, Joel M.; Sisson, James B.

    2003-01-01

    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.

  3. Improved Methodology for Surface and Atmospheric Soundings, Error Estimates, and Quality Control Procedures: the AIRS Science Team Version-6 Retrieval Algorithm

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Blaisdell, John; Iredell, Lena

    2014-01-01

    The AIRS Science Team Version-6 AIRS/AMSU retrieval algorithm is now operational at the Goddard DISC. AIRS Version-6 level-2 products are generated near real-time at the Goddard DISC and all level-2 and level-3 products are available starting from September 2002. This paper describes some of the significant improvements in retrieval methodology contained in the Version-6 retrieval algorithm compared to that previously used in Version-5. In particular, the AIRS Science Team made major improvements with regard to the algorithms used to 1) derive surface skin temperature and surface spectral emissivity; 2) generate the initial state used to start the cloud clearing and retrieval procedures; and 3) derive error estimates and use them for Quality Control. Significant improvements have also been made in the generation of cloud parameters. In addition to the basic AIRS/AMSU mode, Version-6 also operates in an AIRS Only (AO) mode which produces results almost as good as those of the full AIRS/AMSU mode. This paper also demonstrates the improvements of some AIRS Version-6 and Version-6 AO products compared to those obtained using Version-5.

  4. Compensations during Unsteady Locomotion.

    PubMed

    Qiao, Mu; Jindrich, Devin L

    2014-12-01

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

  5. 50 CFR 296.4 - Claims eligible for compensation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Claims eligible for compensation. 296.4 Section 296.4 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE CONTINENTAL SHELF FISHERMEN'S CONTINGENCY FUND 296.4 Claims eligible...

  6. 50 CFR 296.4 - Claims eligible for compensation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 11 2013-10-01 2013-10-01 false Claims eligible for compensation. 296.4 Section 296.4 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE CONTINENTAL SHELF FISHERMEN'S CONTINGENCY FUND 296.4 Claims eligible...

  7. 50 CFR 600.245 - Council member compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Council member compensation. 600.245 Section 600.245 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MAGNUSON-STEVENS ACT PROVISIONS Council Membership §...

  8. 38 CFR 3.5 - Dependency and indemnity compensation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... receive death pension instead of such compensation. (Authority: 38 U.S.C. 1317) (d) Group life insurance... Geodetic Survey, the Environmental Science Services Administration, or the National Oceanic and Atmospheric... Life Insurance Act of 1954 (Pub. L. 598, 83d Cong., as amended) based on the same death....

  9. Temperature compensated photovoltaic array

    DOEpatents

    Mosher, D.M.

    1997-11-18

    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.

  10. Temperature compensated photovoltaic array

    DOEpatents

    Mosher, Dan Michael

    1997-11-18

    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.

  11. Fixman compensating potential for general branched molecules.

    PubMed

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

    2013-12-28

    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

  12. Fixman compensating potential for general branched molecules

    SciTech Connect

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

    2013-12-28

    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.

  13. Topography-Dependent Motion Compensation: Application to UAVSAR Data

    NASA Technical Reports Server (NTRS)

    Jones, Cathleen E.; Hensley, Scott; Michel, Thierry

    2009-01-01

    The UAVSAR L-band synthetic aperture radar system has been designed for repeat track interferometry in support of Earth science applications that require high-precision measurements of small surface deformations over timescales from hours to years. Conventional motion compensation algorithms, which are based upon assumptions of a narrow beam and flat terrain, yield unacceptably large errors in areas with even moderate topographic relief, i.e., in most areas of interest. This often limits the ability to achieve sub-centimeter surface change detection over significant portions of an acquired scene. To reduce this source of error in the interferometric phase, we have implemented an advanced motion compensation algorithm that corrects for the scene topography and radar beam width. Here we discuss the algorithm used, its implementation in the UAVSAR data processor, and the improvement in interferometric phase and correlation achieved in areas with significant topographic relief.

  14. GIFTS SM EDU Level 1B algorithms

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

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

  15. GIFTS SM EDU Level 1B Algorithms

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  16. More rain compensation results

    NASA Technical Reports Server (NTRS)

    Sworder, D. D.; Vojak, R.

    1992-01-01

    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.

  17. 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)

    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

    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.

  18. Some determinants of compensation decisions.

    PubMed

    Freedman, S M

    1978-09-01

    This research investigated the effects of three variables upon compensation decisions. Results indicated that, in a simulated personnel task, both subordinate pay equity and subordinate equity off the job directly affected subjects' decisions. The strength of the subordinate's demand for a raise also influenced compensation decisions through its interaction with each of the other two variables. PMID:10246525

  19. Edgecombe Community College Compensation Plan.

    ERIC Educational Resources Information Center

    Edgecombe Community Coll., Tarboro, NC.

    This document presents Edgecombe Community College's (North Carolina) compensation plan. This plan was created to provide equitable administration of pay practices, taking into account internal equity within the institution and external competitiveness to make sure that compensation levels are market-driven and the institution can attract and…

  20. Alternative Teacher Compensation: A Primer

    ERIC Educational Resources Information Center

    Koppich, Julia E.; Rigby, Jessica

    2009-01-01

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

  1. Strategies for redesigning physician compensation.

    PubMed

    Corneliuson, Susan K; Hackman, Brian

    2014-07-01

    Five principles should guide a health system's efforts to redesign its physician compensation plan: Goals should be aligned. Goals should not focus solely on productivity. Metrics should be not only individual, but also team-based. Initial metrics should be selected from among those currently being used. Compensation plans should avoid long-term commitments. PMID:25076639

  2. The use of MODIS 250 m bands to improve the MODIS 1 km ocean color atmospheric correction algorithm in turbid water

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Quan, Wenting; Wen, Zhenhe; Cui, Tingwei

    2013-05-01

    "Clear water" is a scale-dependent concept, so it is more likely to successfully find the "clear water" from images with smaller scale than that with larger scale data. In this study, an optimal spectral relationship of moderate-resolution imaging spectroradiometer (MODIS) 250 m and 1 km resolution data at near-infrared bands (OSRLM) is constructed for converting pseudo "clear water" reflectance at 859 nm to those at 748 and 869 nm. According to scale effects, the satellite-observed pseudo "clear water" reflectance is greater than 5.18%, larger than that derived from OSRLM model. An atmospheric correction model for MODIS 1km data using pseudo "clear water" reflectance of MODIS 250 m data (ACMM) was developed for improving the performance of traditional "clear water" atmospheric correction model (CWAC). The model validation results indicate that ACMM model has a better performance than CWAC model. By comparison, the uncertainty decreases by 19.18% in the use of ACMM model over CWAC model for deriving water-leaving reflectance in Taihu Lake, China. This uncertainty is significantly reduced in water-leaving reflectance estimation due to partial removal of scale effects on "clear water". These findings imply that satellite-derived aerosol scattering contribution at smaller scale usually has a better performance than that at larger scale.

  3. Temperature compensation method using readout signals of ring laser gyroscope.

    PubMed

    Li, Geng; Wang, Fei; Xiao, Guangzong; Wei, Guo; Zhang, Pengfei; Long, Xingwu

    2015-05-18

    Traditional compensation methods using temperature-related parameters have little effect when the ring laser gyroscope (RLG) bias changes rapidly. To solve this problem, a novel RLG bias temperature compensation method using readout signals is proposed in this paper. Combined with the least squares support vector machine (LS-SVM) algorithm, the novel method can improve the precision of the RLG bias. Experiments show that by utilizing the readout signals in the LS-SVM model, the RLG bias stability can be significantly raised compared to the original data. The novel method proposed in this paper is shown to be feasible, even when the RLG bias changes rapidly. PMID:26074582

  4. Using a Quadtree Algorithm To Assess Line of Sight

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Perachio, Adrian A. (Principal Investigator)

    1996-01-01

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

  6. Compensation and gender.

    PubMed

    1994-05-01

    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

  7. Compensated pulsed alternator

    DOEpatents

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

    1980-01-01

    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.

  8. Genetic algorithms

    NASA Technical Reports Server (NTRS)

    Wang, Lui; Bayer, Steven E.

    1991-01-01

    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.

  9. Radiation compensator for gas sensors

    SciTech Connect

    Rudek, F.

    1985-02-05

    A compensator device for providing direct and automatic correction of electrolytic gas sensor performance anomalies caused by exposure of the sensor to high levels of ionizing radiation. The compensator device, which compensates for changes in sensor performance while operating in a radiation field, provides an electromotive force which directly cancels that portion of the electromotive force developed by the active electrolytic gas sensor produced by the radiation rather than by presence of the gas. The compensating device is constructed in the same configuration as the active electrolytic sensor with the exception that the sensing electrode of the compensating device is not exposed to the sample gas environment. The sensor and compensator device are connected in a circuit such that their electromotive forces oppose one another, thereby determining the difference between the signals so that the radiation induced component is removed, and only the signal representing the partial pressure of gas remains. An alternate embodiment wherein the compensating signal is generated within the same sensor housing by the addition of one more electrode is also disclosed.

  10. Transponder-aided joint calibration and synchronization compensation for distributed radar systems.

    PubMed

    Wang, Wen-Qin

    2015-01-01

    High-precision radiometric calibration and synchronization compensation must be provided for distributed radar system due to separate transmitters and receivers. This paper proposes a transponder-aided joint radiometric calibration, motion compensation and synchronization for distributed radar remote sensing. As the transponder signal can be separated from the normal radar returns, it is used to calibrate the distributed radar for radiometry. Meanwhile, the distributed radar motion compensation and synchronization compensation algorithms are presented by utilizing the transponder signals. This method requires no hardware modifications to both the normal radar transmitter and receiver and no change to the operating pulse repetition frequency (PRF). The distributed radar radiometric calibration and synchronization compensation require only one transponder, but the motion compensation requires six transponders because there are six independent variables in the distributed radar geometry. Furthermore, a maximum likelihood method is used to estimate the transponder signal parameters. The proposed methods are verified by simulation results. PMID:25794158

  11. Transponder-Aided Joint Calibration and Synchronization Compensation for Distributed Radar Systems

    PubMed Central

    Wang, Wen-Qin

    2015-01-01

    High-precision radiometric calibration and synchronization compensation must be provided for distributed radar system due to separate transmitters and receivers. This paper proposes a transponder-aided joint radiometric calibration, motion compensation and synchronization for distributed radar remote sensing. As the transponder signal can be separated from the normal radar returns, it is used to calibrate the distributed radar for radiometry. Meanwhile, the distributed radar motion compensation and synchronization compensation algorithms are presented by utilizing the transponder signals. This method requires no hardware modifications to both the normal radar transmitter and receiver and no change to the operating pulse repetition frequency (PRF). The distributed radar radiometric calibration and synchronization compensation require only one transponder, but the motion compensation requires six transponders because there are six independent variables in the distributed radar geometry. Furthermore, a maximum likelihood method is used to estimate the transponder signal parameters. The proposed methods are verified by simulation results. PMID:25794158

  12. Atmospheric turbulence mitigation in free space optical communication systems with retro-modulators

    NASA Astrophysics Data System (ADS)

    Saint Georges, Eric

    After a brief description of the Free Space Optical communication systems that has been developed for both direct mode and retro mode and which are used by the Naval Research Laboratory for their research on modulating retro-reflectors, this paper presents the implementation of an efficient cone-tracking algorithm for the optimization of the beam pointing in retro-mode links. It is shown how the algorithm can be augmented in order to support the same function in direct-mode links. Furthermore it is shown how this cone-tracking technique, implemented initially to compensate for the system misalignment and the slow drifts related to temperature or remote distance changes, can be used to characterize the beam wander in the far field. The results of a beam wander measurement experiment are then discussed. These results led to developing a multi-dithering adaptive optics algorithm to mitigate the effect of atmospheric turbulence in a retro-mode link. This algorithm works by optimizing the power coupled into the MRR and therefore reducing the fluctuations of the power reflected back to the Interrogator. This algorithm can be thought of as an extension of the cone-tracking technique to higher order aberrations. Finally, results are presented of a proof of concept laboratory experiment of this single-metric multi-dithering modal AO algorithm applied to the coupling into a single mode fiber. The results show the successful convergence of the simultaneous compensation of six low order aberrations. The conclusion is that using faster hardware these encouraging results could eventually lead to a significant reduction of the power fluctuation induced by the atmospheric turbulence in a FSO retro-mode link.

  13. Motion compensation of airborne synthetic aperture radars using autofocus

    NASA Astrophysics Data System (ADS)

    Blacknell, D.; Quegan, S.

    Conventional motion compensation schemes correct for unwanted SAR platform motions using information from an inertial measurement unit (IMU). Autofocus techniques, which focus SAR images, produce an 'autofocus parameter' which is related to the platform motion. In this paper, strong evidence is presented to support the assumption that the contrast optimization autofocus algorithm behaves as a least-squares quadratic fitting to the SAR platform trajectory. Using this assumption, the relationship between the autofocus parameter and across-track accelerations of the SAR platform is derived. This allows the SAR platform motion to be estimated from the autofocus parameter measurements and incorporated in a motion compensation scheme, instead of IMU measurements. Three implementations of motion compensation using autofocus are compared, and the achievable image quality is quantified.

  14. Temperature-compensating dc restorer

    NASA Technical Reports Server (NTRS)

    Thomas, H. M.

    1980-01-01

    Circuit provides stable references restoration in addition to temperature compensation. Possible TV monitor applications include traffic and security surveillance systems, where cameras are subject to environmental extremes, as in unheated warehouses or outdoors.

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

    NASA Astrophysics Data System (ADS)

    Notarpietro, Riccardo; Cucca, Manuela; Perona, Giovanni

    2010-05-01

    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. Sans (Politecnico di Milano) for the COMO GPS network data acquisition and data processing.

  16. An Alternate Method to Springback Compensation for Sheet Metal Forming

    PubMed Central

    Omar, Badrul; Jusoff, Kamaruzaman

    2014-01-01

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

  17. An alternate method to springback compensation for sheet metal forming.

    PubMed

    Siswanto, Waluyo Adi; Anggono, Agus Dwi; Omar, Badrul; Jusoff, Kamaruzaman

    2014-01-01

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

  18. GIFTS SM EDU Data Processing and Algorithms

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  19. Quantum Algorithms

    NASA Technical Reports Server (NTRS)

    Abrams, D.; Williams, C.

    1999-01-01

    This thesis describes several new quantum algorithms. These include a polynomial time algorithm that uses a quantum fast Fourier transform to find eigenvalues and eigenvectors of a Hamiltonian operator, and that can be applied in cases for which all know classical algorithms require exponential time.

  20. Stray light compensation for dust analysers based on light scattering

    NASA Astrophysics Data System (ADS)

    Molfese, C.; Della Corte, V.; Palumbo, P.; Esposito, F.; Colangeli, L.

    2010-04-01

    One of the key issues concerning the measurement of size and density of dust grains based on light scattering system is the compensation of the stray light due to the optical components misalignment and to the possible contamination of these components by the dust particles during the measurement runs. This paper focuses on the case study of MEDUSA (Martian Environmental DUst Systematic Analyzer), one of the experiments initially selected for the ExoMars mission, planned by the European Space Agency (ESA), with the scientific objective to study water and dust in Mars atmosphere. The MEDUSA experiment foresees an Optical System (OS) aimed at measuring atmospheric dust content and size distribution. One pump assures that the proper gas and dust flow circulates inside the instrument. This paper reports the description and trade off analysis of several techniques for the stray-light compensation implemented on the MEDUSA OS Proximity Electronics (PE) Test Board (2006), designed and manufactured by INAF-Osservatorio Astronomico di Capodimonte, in the frame of the MEDUSA Bread Board (B/B) activities. The PE Test Board can implement more than one compensation mode, such as: AC coupling, DC coupling with offset compensation via external loop and DC coupling with offset compensation via on board HW loop. The choice among the mentioned compensation modes shall be done also according to the configuration of the overall acquisition system, implemented by the Main Electronics (ME), as explained in the reported trade-off analysis. For the architecture configuration of the industrial breadboard (2008) the preferred solution was the one based on the DC coupling with on board HW loop, for which some test results are reported.

  1. X-Chromosome dosage compensation.

    PubMed Central

    Meyer, Barbara J

    2005-01-01

    In mammals, flies, and worms, sex is determined by distinctive regulatory mechanisms that cause males (XO or XY) and females (XX) to differ in their dose of X chromosomes. In each species, an essential X chromosome-wide process called dosage compensation ensures that somatic cells of either sex express equal levels of X-linked gene products. The strategies used to achieve dosage compensation are diverse, but in all cases, specialized complexes are targeted specifically to the X chromosome(s) of only one sex to regulate transcript levels. In C. elegans, this sex-specific targeting of the dosage compensation complex (DCC) is controlled by the same developmental signal that establishes sex, the ratio of X chromosomes to sets of autosomes (X:A signal). Molecular components of this chromosome counting process have been defined. Following a common step of regulation, sex determination and dosage compensation are controlled by distinct genetic pathways. C. elegans dosage compensation is implemented by a protein complex that binds both X chromosomes of hermaphrodites to reduce transcript levels by one-half. The dosage compensation complex resembles the conserved 13S condensin complex required for both mitotic and meiotic chromosome resolution and condensation, implying the recruitment of ancient proteins to the new task of regulating gene expression. Within each C. elegans somatic cell, one of the DCC components also participates in the separate mitotic/meiotic condensin complex. Other DCC components play pivotal roles in regulating the number and distribution of crossovers during meiosis. The strategy by which C. elegans X chromosomes attract the condensin-like DCC is known. Small, well-dispersed X-recognition elements act as entry sites to recruit the dosage compensation complex and to nucleate spreading of the complex to X regions that lack recruitment sites. In this manner, a repressed chromatin state is spread in cis over short or long distances, thus establishing the global, epigenetic regulation of X chromosomes that is maintained throughout the lifetime of hermaphrodites. PMID:18050416

  2. Tip--tilt compensation for astronomical imaging

    SciTech Connect

    Olivier, S.S. ); Gavel, D.T. )

    1994-01-01

    We present a performance analysis of tip--tilt-compensation systems that use natural stars as tilt references. Taking into account properties of the atmosphere and of the galactic stellar populations, we optimize operating parameters over the system to determine performance limits for several varieties of tip--tilt-compensation system operating on a 10-m telescope on Mauna Kea, Hawaii. We find that, for systems that use a single tilt reference star, if the image of the star is uncorrected, a one-axis root-mean-square tilt residual of less than 190 nrad can be obtained for at least 99% of all astronomical objects, whereas if the image of the tilt reference star is fully corrected this limit drops to 90 nrad. For systems that use two tilt reference stars the limits drop to 160 nrad if the images of the stars are uncorrected and to 60 nrad if the images of the stars are fully corrected. These residual tilt levels would permit [ital V]-band images with long-exposure resolution of 8.5, 4.2, 7.3, and 2.9 times the diffraction limit, respectively, where the diffraction-limited resolution in the [ital V] band is 0.011 arcsec. These results may be compared with the typical seeing of 0.75 arcsec.

  3. Efficient inhomogeneity compensation using fuzzy c-means clustering models.

    PubMed

    Szilágyi, László; Szilágyi, Sándor M; Benyó, Balázs

    2012-10-01

    Intensity inhomogeneity or intensity non-uniformity (INU) is an undesired phenomenon that represents the main obstacle for magnetic resonance (MR) image segmentation and registration methods. Various techniques have been proposed to eliminate or compensate the INU, most of which are embedded into classification or clustering algorithms, they generally have difficulties when INU reaches high amplitudes and usually suffer from high computational load. This study reformulates the design of c-means clustering based INU compensation techniques by identifying and separating those globally working computationally costly operations that can be applied to gray intensity levels instead of individual pixels. The theoretical assumptions are demonstrated using the fuzzy c-means algorithm, but the proposed modification is compatible with a various range of c-means clustering based INU compensation and MR image segmentation algorithms. Experiments carried out using synthetic phantoms and real MR images indicate that the proposed approach produces practically the same segmentation accuracy as the conventional formulation, but 20-30 times faster. PMID:22405524

  4. Pneumatic distortion compensation for aircraft surface pressure sensing devices

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.; Leondes, Cornelius T.

    1991-01-01

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

  5. 29 CFR 525.6 - Compensable time.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false Compensable time. 525.6 Section 525.6 Labor Regulations... WITH DISABILITIES UNDER SPECIAL CERTIFICATES 525.6 Compensable time. Individuals employed subject to this part must be compensated for all hours worked. Compensable time includes not only those...

  6. 29 CFR 525.6 - Compensable time.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false Compensable time. 525.6 Section 525.6 Labor Regulations... WITH DISABILITIES UNDER SPECIAL CERTIFICATES 525.6 Compensable time. Individuals employed subject to this part must be compensated for all hours worked. Compensable time includes not only those...

  7. 29 CFR 525.6 - Compensable time.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false Compensable time. 525.6 Section 525.6 Labor Regulations... WITH DISABILITIES UNDER SPECIAL CERTIFICATES 525.6 Compensable time. Individuals employed subject to this part must be compensated for all hours worked. Compensable time includes not only those...

  8. 48 CFR 970.2270 - Unemployment compensation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Unemployment compensation... Unemployment compensation. (a) Each state has its own unemployment compensation system to provide payments to... unemployment compensation benefits through a payroll tax on employers. Most DOE contractors are subject to...

  9. 48 CFR 970.2270 - Unemployment compensation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 5 2013-10-01 2013-10-01 false Unemployment compensation... Unemployment compensation. (a) Each state has its own unemployment compensation system to provide payments to... unemployment compensation benefits through a payroll tax on employers. Most DOE contractors are subject to...

  10. 48 CFR 970.2270 - Unemployment compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Unemployment compensation... Unemployment compensation. (a) Each state has its own unemployment compensation system to provide payments to... unemployment compensation benefits through a payroll tax on employers. Most DOE contractors are subject to...

  11. 48 CFR 970.2270 - Unemployment compensation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Unemployment compensation... Unemployment compensation. (a) Each state has its own unemployment compensation system to provide payments to... unemployment compensation benefits through a payroll tax on employers. Most DOE contractors are subject to...

  12. 38 CFR 3.459 - Death compensation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Death compensation. 3.459 Section 3.459 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity Compensation Apportionments § 3.459 Death compensation. (a)...

  13. 38 CFR 3.459 - Death compensation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Death compensation. 3.459 Section 3.459 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity Compensation Apportionments § 3.459 Death compensation. (a)...

  14. 38 CFR 3.459 - Death compensation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Death compensation. 3.459 Section 3.459 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity Compensation Apportionments § 3.459 Death compensation. (a)...

  15. 38 CFR 3.459 - Death compensation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Death compensation. 3.459 Section 3.459 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity Compensation Apportionments § 3.459 Death compensation. (a)...

  16. 38 CFR 3.459 - Death compensation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Death compensation. 3.459 Section 3.459 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity Compensation Apportionments § 3.459 Death compensation. (a)...

  17. 48 CFR 970.2270 - Unemployment compensation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Unemployment compensation... Unemployment compensation. (a) Each state has its own unemployment compensation system to provide payments to... unemployment compensation benefits through a payroll tax on employers. Most DOE contractors are subject to...

  18. EMITTANCE COMPENSATION FOR MAGNETIZED BEAMS

    SciTech Connect

    KEWISCH,J.; CHANG, X.

    2007-06-25

    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.

  19. Compensation and Recovery From Injury

    PubMed Central

    Beals, Rodney K.

    1984-01-01

    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

  20. Compensation for electrical converter nonlinearities

    DOEpatents

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

    2013-11-19

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

  1. Simulation of selective passive compensation

    SciTech Connect

    Spikings, C.R.; Putley, D. )

    1991-01-01

    Compulsators have attracted a great deal of interest over the last few years as a way of providing repetitive high current millisecond pulses. The compulsator stores energy in a rotational form and works on a similar principle to a conventional alternator except that its internal impedance is reduced through compensating currents allowing greater currents to be drawn. This paper presents the theory behind selective passive compensation and presents some results from the computer simulation of a railgun powered by a selective passive compulsator. These results show that compulsator can be configured to produce flat topped current pulses into a railgun load. A test compulsator with active compensation has previously been designed and built by Culham Laboratory.

  2. Atmospheric turbulence compensation with laser phase shifting interferometry

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

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

  3. Earth, atmosphere

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.

    1991-01-01

    Present understanding of the earth's atmosphere is briefly reviewed. The structure and composition of the atmosphere are described. The origin of the atmosphere and the factors involved in global atmospheric change are addressed.

  4. Polarization compensator for optical communications

    NASA Technical Reports Server (NTRS)

    Fitzmaurice, M. W.; Abshire, J. B. (inventors)

    1976-01-01

    An optical data communication system is provided whereby two orthogonal polarization states of a light beam carrier correspond to digital states. In such a system, automatic polarization compensation is provided by applying a dither modulating voltage to a cell exhibiting the electro-optic effect. The cell controls the relative phase of electric field components of an input light beam enabling the dither frequency component of the difference of the instantaneous powers in the two polarization states to be coherently detected. A signal derived from the coherent detection process is fed back to the cell via an integrator to form polarization bias compensating servo loop ot Type 1.

  5. New Adaptive Method for IQ Imbalance Compensation of Quadrature Modulators in Predistortion Systems

    NASA Astrophysics Data System (ADS)

    Zareian, Hassan; Vakili, Vahid Tabataba

    2009-12-01

    Imperfections in quadrature modulators (QMs), such as inphase and quadrature (IQ) imbalance, can severely impact the performance of power amplifier (PA) linearization systems, in particular in adaptive digital predistorters (PDs). In this paper, we first analyze the effect of IQ imbalance on the performance of a memory orthogonal polynomials predistorter (MOP PD), and then we propose a new adaptive algorithm to estimate and compensate the unknown IQ imbalance in QM. Unlike previous compensation techniques, the proposed method was capable of online IQ imbalance compensation with faster convergence, and no special calibration or training signals were needed. The effectiveness of the proposed IQ imbalance compensator was validated by simulations. The results clearly show the performance of the MOP PD to be enhanced significantly by adding the proposed IQ imbalance compensator.

  6. Error analysis for a temperature and emissivity retrieval algorithm for hyperspectral imaging data

    NASA Astrophysics Data System (ADS)

    Borel, Christoph

    2007-04-01

    In the hyperspectral thermal data analysis temperature-emissivity separation has the same function as reflectance retrieval in the visible and shortwave infrared. The problem however is more complicated since in the thermal the surface emits and reflects radiation. The measured radiance is a function of the materials' surface emissivity and temperature, reflected down welling radiance (clear sky, clouds environment) and the path radiance (temperature and gas (e.g. water vapor, ozone) profiles). The current implementation of the Automatic Retrieval of Temperature and EMIssivity using Spectral Smoothness (ARTEMISS) uses look-up-tables (LUT) to infer the best fitting atmosphere which results in the smallest residual to the In-Scene Atmospheric Compensation (ISAC) estimated transmission. Over last few years we have developed an end-to-end simulation of the hyper spectral exploitation process by generating synthetic data to simulate datasets with "known" ground truth, modeling propagation through the atmosphere, adding sensor effects (telescope, detector, read-out electronics), radiometric and spectral calibration, and test the temperature emissivity separation algorithm. We will present an error analysis where we shifted the band centers, varied the full-width half maximum (FWHM) of the spectral response function, changed the spectral resolution, added noise and varied the atmospheric model. We will also discuss a general method to retrieve the spectral smile as a function of wavelength and the FWHM from hyperspectral data with only approximate spectral calibration. We found that our algorithm has trouble finding a unique solution when the watervapor exceeds about 3 g/cm2 and will discuss remedies for this situation. To speedup the LUT generation we have developed fast and robust initial atmospheric parameter estimators (water vapor, ozone, near surface atmospheric layer temperature) based on channel ratios and brightness temperatures in atmospheric absorption regions for the LWIR.

  7. 78 FR 28441 - Executive Compensation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-14

    ...The Federal Housing Finance Agency (FHFA) is issuing an interim final rule with request for comments that sets forth requirements and processes with respect to compensation provided to executive officers by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, the Federal Home Loan Banks, and the Federal Home Loan Bank System's Office of Finance, consistent......

  8. Clarification of Workmen's Compensation Insurance.

    ERIC Educational Resources Information Center

    Shapley, Allen E.

    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,

  9. Synchrony - Cyberknife Respiratory Compensation Technology

    SciTech Connect

    Ozhasoglu, Cihat Saw, Cheng B.; Chen Hungcheng; Burton, Steven; Komanduri, Krishna; Yue, Ning J.; Huq, Saiful M.; Heron, Dwight E.

    2008-07-01

    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.

  10. Compensation for oil pollution damage

    NASA Astrophysics Data System (ADS)

    Matugina, E. G.; Glyzina, T. S.; Kolbysheva, Yu V.; Klyuchnikov, A. S.; Vusovich, O. V.

    2015-11-01

    The commitment of national industries to traditional energy sources, as well as constantly growing energy demand combined with adverse environmental impact of petroleum production and transportation urge to establish and maintain an appropriate legal and administrative framework for oil pollution damage compensation. The article considers management strategies for petroleum companies that embrace not only production benefits but also environmental issues.

  11. Voltage Fluctuation Compensator for Shinkansen

    NASA Astrophysics Data System (ADS)

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

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

  12. Compensated amorphous silicon solar cell

    DOEpatents

    Carlson, David E. (Yardley, PA)

    1980-01-01

    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.

  13. Strategic Design of Teacher Compensation

    ERIC Educational Resources Information Center

    Shields, Regis

    2012-01-01

    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

  14. Acceleration insensitive fluid expansion compensator

    NASA Technical Reports Server (NTRS)

    Hughes, L. F.

    1968-01-01

    Device compensates for temperature and acceleration effects on a fluid-floated mass in a sealed container of a high performance angular or acceleration sensing instrument. It is used in precision instruments for regulation of gases or liquids in a moving body.

  15. Concealing compensation from the IRS.

    PubMed

    Burda, D; Greene, J

    1991-01-28

    Tougher reporting requirements from the Internal Revenue Service are prompting some not-for-profit hospitals to seek ways to hide compensation arrangements from the public and the media. Critics believe those tactics could get hospitals in hot water with the law, especially now that the IRS has launched a new, aggressive auditing offensive. PMID:10108763

  16. Merit Compensation and Higher Education.

    ERIC Educational Resources Information Center

    Counelis, James Steve

    The concept of merit compensation is clarified from both administrative and faculty perspectives, and the conceptual sources of the controversy surrounding "merit" are addressed. Using the lexical tradition of the verb "to merit," four distinct semantic components are identified: to earn, to deserve, to value or give preference, and to obtain

  17. New Perspectives on Compensation Strategies.

    ERIC Educational Resources Information Center

    Mitchell, Anne; Morgan, Gwen

    Low compensation, in both earnings and benefits, and the resulting high turnover of staff and low quality of programs in early childhood care and education are a national problem. Noting that how we define and view the problem, and the strategies we adopt to solve it, may differ depending on perspectives and disciplines, this paper expands the

  18. Promising Strategies for Increasing Compensation.

    ERIC Educational Resources Information Center

    Young Children, 2000

    2000-01-01

    Despite rising demand for high-quality child care, the norm for early childhood staff is low salaries, few benefits, and difficult working conditions. This article provides an overview of compensation of early childhood professionals, and describes some state and local initiatives that address the need for funding and policies that support a

  19. Motion-compensated blind deconvolution of scanning laser opthalmoscope imagery

    NASA Astrophysics Data System (ADS)

    O'Connor, Nathan J.; Bartsch, Dirk-Uwe G.; Freeman, William R.; Holmes, Timothy J.

    1998-06-01

    A deconvolution algorithm for use with scanning laser ophthalmoscope (SLO) data is being developed. The SLO is fundamentally a confocal microscope in which the objective lens is the human ocular lens. 3D data is collected by raster scanning to form images at different depths in retinal and choroidal layers. In this way, 3D anatomy may be imaged and stored as a series of optical sections.Given the poor optical quality of the human lens and random eye motion during data acquisition, any deconvolution method applied to SLO data must be able to account for distortions present in the observed data. The algorithm presented compensates for image warping and frame-to-frame displacement due to random eye motion, smearing along the optic axis, sensor saturation, and other problems. A preprocessing step is first used to compensate for frame-to-frame image displacement. The image warping, caused by random eye motion during raster scanning, is corrected. Finally, a maximum likelihood based blind deconvolution algorithm is used to correct severe blurring along the optic axis. The blind deconvolution algorithm contains an iterative search for subpixel displacements remaining after image warping and frame-to-frame displacements are corrected. This iterative search is formulated to ensure that the likelihood functional is non-decreasing.

  20. Delay compensation in integrated communication and control systems. I - Conceptual development and analysis

    NASA Technical Reports Server (NTRS)

    Luck, Rogelio; Ray, Asok

    1990-01-01

    A procedure for compensating for the effects of distributed network-induced delays in integrated communication and control systems (ICCS) is proposed. The problem of analyzing systems with time-varying and possibly stochastic delays could be circumvented by use of a deterministic observer which is designed to perform under certain restrictive but realistic assumptions. The proposed delay-compensation algorithm is based on a deterministic state estimator and a linear state-variable-feedback control law. The deterministic observer can be replaced by a stochastic observer without any structural modifications of the delay compensation algorithm. However, if a feedforward-feedback control law is chosen instead of the state-variable feedback control law, the observer must be modified as a conventional nondelayed system would be. Under these circumstances, the delay compensation algorithm would be accordingly changed. The separation principle of the classical Luenberger observer holds true for the proposed delay compensator. The algorithm is suitable for ICCS in advanced aircraft, spacecraft, manufacturing automation, and chemical process applications.

  1. Attenuation compensation in multicomponent Gaussian beam prestack depth migration

    NASA Astrophysics Data System (ADS)

    Wu, Juan; Chen, Xiao-Hong; Bai, Min; Liu, Guo-Chang

    2015-06-01

    Gaussian beam prestack depth migration is an accurate imaging method of subsurface media. Prestack depth migration of multicomponent seismic data improves the accuracy of imaging subsurface complex geological structures. Viscoelastic prestack depth migration is of practical significance because it considers the viscosity of the subsurface media. We use Gaussian beam migration to compensate for the attenuation in multicomponent seismic data. First, we use the Gaussian beam method to simulate the wave propagation in a viscoelastic medium and introduce the complex velocity Q-related and exact viscoelastic Zoeppritz equation. Second, we discuss PP- and PS-wave Gaussian beam prestack depth migration algorithms for common-shot gathers to derive expressions for the attenuation and compensation. The algorithms correct the amplitude attenuation and phase distortion caused by Q, and realize multicomponent Gaussian beam prestack depth migration based on the attenuation compensation and account for the effect of inaccurate Q on migration. Numerical modeling suggests that the imaging resolution of viscoelastic Gaussian beam prestack depth migration is high when the viscosity of the subsurface is considered.

  2. Jovian atmospheres

    SciTech Connect

    Allison, M.; Travis, L.D.

    1986-10-01

    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.

  3. Temperature compensation for miniaturized magnetic sector

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva P. (Inventor)

    2002-01-01

    Temperature compensation for a magnetic sector used in mass spectrometry. A high temperature dependant magnetic sector is used. This magnetic sector is compensated by a magnetic shunt that has opposite temperature characteristics to those of the magnet.

  4. Haplotyping algorithms

    SciTech Connect

    Sobel, E.; Lange, K.; O`Connell, J.R.

    1996-12-31

    Haplotyping is the logical process of inferring gene flow in a pedigree based on phenotyping results at a small number of genetic loci. This paper formalizes the haplotyping problem and suggests four algorithms for haplotype reconstruction. These algorithms range from exhaustive enumeration of all haplotype vectors to combinatorial optimization by simulated annealing. Application of the algorithms to published genetic analyses shows that manual haplotyping is often erroneous. Haplotyping is employed in screening pedigrees for phenotyping errors and in positional cloning of disease genes from conserved haplotypes in population isolates. 26 refs., 6 figs., 3 tabs.

  5. A Resonant Pressure Microsensor Capable of Self-Temperature Compensation

    PubMed Central

    Li, Yinan; Wang, Junbo; Luo, Zhenyu; Chen, Deyong; Chen, Jian

    2015-01-01

    Resonant pressure microsensors are widely used in the fields of aerospace exploration and atmospheric pressure monitoring due to their advantages of quasi-digital output and long-term stability, which, however, requires the use of additional temperature sensors for temperature compensation. This paper presents a resonant pressure microsensor capable of self-temperature compensation without the need for additional temperature sensors. Two doubly-clamped H type resonant beams were arranged on the pressure diaphragm, which functions as a differential output in response to pressure changes. Based on calibration of a group of intrinsic resonant frequencies at different pressure and temperature values, the functions with inputs of two resonant frequencies and outputs of temperature and pressure under measurement were obtained and thus the disturbance of temperature variations on resonant frequency shifts was properly addressed. Before compensation, the maximal errors of the measured pressure values were over 1.5% while after compensation, the errors were less than 0.01% of the full pressure scale (temperature range of ?40 C to 70 C and pressure range of 50 kPa to 110 kPa). PMID:25938197

  6. A Cenozoic record of the equatorial Pacific carbonate compensation depth.

    PubMed

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

    2012-08-30

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

  7. Compensated High Temperature Strain Gage

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A device for measuring strain in substrates at high temperatures in which the thermally induced apparent strain is nulled is described. Two gages are used, one active gage and one compensating gage. Both gages are placed on the substrate to be gaged; the active gage is attached such that it responds to mechanical and thermally induced apparent strain while the compensating gage is attached such that it does not respond to mechanical strain and and measures only thermally induced apparent strain. A thermal blanket is placed over the two gages to maintain the gages at the same temperature. The two gages are wired as adjacent arms of a wheatstone bridge which nulls the thermally induced apparent strain giving a true reading of the mechanical strain in the substrate.

  8. Causal compensated perturbations in cosmology

    NASA Technical Reports Server (NTRS)

    Veeraraghavan, Shoba; Stebbins, Albert

    1990-01-01

    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.

  9. Kinesthetic compensation for sensorimotor rearrangements.

    PubMed

    Ellis, Stephen R; Adelstein, Bernard D

    2009-11-01

    The authors report a new sensorimotor phenomenon in which participants use hand-sensed kinesthetic information to compensate for rotational sensorimotor rearrangements. This compensation benefits from conscious awareness and is related to hand posture. The technique can reduce control inefficiency with some misalignments by as much as 64%. The results support Y. Guiard's (1987) suggestion that in bimanual tasks one hand provides an operational frame of reference for the other hand as in a closed kinematic chain. Results with right-handed participants show that the right and left hands are equally effective at providing such a cue. A constant-angular-targeting-error model, similar to that used for hand movements by H. Cunningham and I. Vardi (1990) and for walking by S. K. Rushton, J. M. Harris, M. R. Lloyd, and J. P. Wann (1998), is used to model the trajectories of targeting hand movements demonstrating the phenomenon. The model provides a natural parameter of the error. PMID:19581219

  10. 14 CFR 158.53 - Collection compensation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Collection compensation. 158.53 Section 158.53 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS PASSENGER FACILITY CHARGES (PFC'S) Collection, Handling, and Remittance of PFC's 158.53 Collection compensation. (a) As compensation...

  11. 75 FR 22679 - Sound Incentive Compensation Guidance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-29

    ... Office of Thrift Supervision Sound Incentive Compensation Guidance AGENCY: Office of Thrift Supervision... collection. Title of Proposal: Sound Incentive Compensation Guidance. OMB Number: 1550-0NEW. Form Number: N/A... principles and the guidance are consistent with the Principles for Sound Compensation Practices adopted...

  12. 75 FR 53023 - Sound Incentive Compensation Guidance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-30

    ... Office of Thrift Supervision Sound Incentive Compensation Guidance AGENCY: Office of Thrift Supervision... collection. Title of Proposal: Sound Incentive Compensation Guidance. OMB Number: 1550-0129. Form Number: N/A... principles and the guidance are consistent with the Principles for Sound Compensation Practices adopted...

  13. Incentives, School Organization and Teacher Compensation.

    ERIC Educational Resources Information Center

    Odden, Allan

    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

  14. Atmospheric electrification

    NASA Technical Reports Server (NTRS)

    Kasemir, H. W.

    1978-01-01

    Research areas of atmospheric electricity that could be explored from the shuttle or the tethered satellite are discussed. Emphasis is placed on atmospheric current flow and telluric currents. A model depicting the atmospheric electric global circuit is presented.

  15. Adaptive optimization for pilot-tone aided phase noise compensation

    NASA Astrophysics Data System (ADS)

    Cui, Sheng; Xu, Mengran; Xia, Wenjuan; Ke, Chanjian; Xia, Zijie; Liu, Deming

    2015-11-01

    Pilot-tone (PT) aided phase noise compensation algorithm is very simple and effective, especially for flexible optical networks, because the phase noise coming from both Tx/Rx lasers and nonlinear cross phase modulation (XPM) during transmission can be adaptively compensated without high computational cost nonlinear operations, or the information of the neighboring channels and the optical link configuration. But to achieve the best performance the two key parameters, i.e. the pilot to signal power ratio and pilot bandpass filter bandwidth need to be optimized. In this paper it is demonstrated that constellation information can be used to adjust the two parameters adaptively to achieve the minimum BER in both homogenous and hybrid single carrier transmission systems with different LPN, XPM and amplified spontaneous emission (ASE) noise distortions.

  16. Compensation Techniques in Accelerator Physics

    SciTech Connect

    Hisham Kamal Sayed

    2011-05-31

    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.

  17. Motion compensated shape error concealment.

    PubMed

    Schuster, Guido M; Katsaggelos, Aggelos K

    2006-02-01

    The introduction of Video Objects (VOs) is one of the innovations of MPEG-4. The alpha-plane of a VO defines its shape at a given instance in time and hence determines the boundary of its texture. In packet-based networks, shape, motion, and texture are subject to loss. While there has been considerable attention paid to the concealment of texture and motion errors, little has been done in the field of shape error concealment. In this paper we propose a post-processing shape error concealment technique that uses the motion compensated boundary information of the previously received alpha-plane. The proposed approach is based on matching received boundary segments in the current frame to the boundary in the previous frame. This matching is achieved by finding a maximally smooth motion vector field. After the current boundary segments are matched to the previous boundary, the missing boundary pieces are reconstructed by motion compensation. Experimental results demonstrating the performance of the proposed motion compensated shape error concealment method, and comparing it with the previously proposed weighted side matching method are presented. PMID:16479820

  18. 38 CFR 21.3023 - Nonduplication; pension, compensation, and dependency and indemnity compensation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2011-07-01 2011-07-01 false Nonduplication; pension, compensation, and dependency and indemnity compensation. 21.3023 Section 21.3023 Pensions, Bonuses, and... Nonduplication; pension, compensation, and dependency and indemnity compensation. (a) Child; age 18. A child...

  19. 38 CFR 21.3023 - Nonduplication; pension, compensation, and dependency and indemnity compensation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2012-07-01 2012-07-01 false Nonduplication; pension, compensation, and dependency and indemnity compensation. 21.3023 Section 21.3023 Pensions, Bonuses, and... Nonduplication; pension, compensation, and dependency and indemnity compensation. (a) Child; age 18. A child...

  20. 38 CFR 21.3023 - Nonduplication; pension, compensation, and dependency and indemnity compensation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2014-07-01 2014-07-01 false Nonduplication; pension, compensation, and dependency and indemnity compensation. 21.3023 Section 21.3023 Pensions, Bonuses, and... Nonduplication; pension, compensation, and dependency and indemnity compensation. (a) Child; age 18. A child...

  1. 38 CFR 21.3023 - Nonduplication; pension, compensation, and dependency and indemnity compensation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2013-07-01 2013-07-01 false Nonduplication; pension, compensation, and dependency and indemnity compensation. 21.3023 Section 21.3023 Pensions, Bonuses, and... Nonduplication; pension, compensation, and dependency and indemnity compensation. (a) Child; age 18. A child...

  2. 38 CFR 21.3023 - Nonduplication; pension, compensation, and dependency and indemnity compensation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Nonduplication; pension, compensation, and dependency and indemnity compensation. 21.3023 Section 21.3023 Pensions, Bonuses, and... Nonduplication; pension, compensation, and dependency and indemnity compensation. (a) Child; age 18. A child...

  3. A Compensation Method of Conductor Parameter for Transient Fault Location

    NASA Astrophysics Data System (ADS)

    Ugbome, Chukwunweike Lucky

    Faults in underground distribution systems are predominantly caused by the deterioration of cable insulation. The inherent nature of underground distribution is such that cables are laid underground and exposed to harmful substances which can cause deterioration of cable insulation. The penetration of water into the cable splice is a common cause of cable deterioration and a common source of transitory sub-cycle cable fault in underground distribution systems. The presence of a sub-cycle fault in a distribution line is not necessarily noticeable and may not cause any protective device to operate due to its short live-span but can be destructive if it is sustained and unattended to. The location of transitory sub-cycle fault in underground cable is fundamentally important in preventing and containing a permanent fault which can potentially result to an unplanned outage. However the location of this type of fault is not easy due to so many unknowns. A few numbers of approaches have been developed for determining the location of short-lived sub-cycle (SLSC) faults, but they approximate the conductor parameter which would reduce the accuracy of the location determination. This thesis develops an algorithm for transitory sub-cycle fault location to compensate for the ignored conductor parameter by employing the X/R ratio of the distribution line. First, a model for transient faults at different locations in underground cable is presented and used to generate the voltage and current waveforms at the source side. Also presented is the performance of the fault location by the uncompensated and compensated algorithms under two configurations of the distribution line: a homogeneous distribution circuit and a heterogeneous distribution line. The result obtained from the performance studies show that the proposed compensation method would help the non-compensated fault location approaches to achieve relatively high accuracy in locating transitory sub-cycle faults in numerous configurations of distribution lines.

  4. Strong eddy compensation for the Gulf Stream heat transport

    NASA Astrophysics Data System (ADS)

    Saenko, Oleg A.

    2015-12-01

    Using a high-resolution ocean model forced with high-resolution atmospheric fields, a 5 year mean heat budget of the upper ocean in the Gulf Stream (GS) region is analyzed. The heat brought to the region with the mean flows along the GS path is 2-3 times larger than the heat loss to the atmosphere, with the difference being balanced by a strong cooling effect due to lateral eddy heat fluxes. However, over a broad area off the Grand Banks, the eddies warm the uppermost ocean layers, partly compensating for the loss of heat to the atmosphere. The upward eddy heat flux, which brings heat from the deeper ocean to the upper layers, is 30-80% of the surface heat loss.

  5. Transport delay compensation for computer-generated imagery systems

    NASA Technical Reports Server (NTRS)

    Mcfarland, Richard E.

    1988-01-01

    In the problem of pure transport delay in a low-pass system, a trade-off exists with respect to performance within and beyond a frequency bandwidth. When activity beyond the band is attenuated because of other considerations, this trade-off may be used to improve the performance within the band. Specifically, transport delay in computer-generated imagery systems is reduced to a manageable problem by recognizing frequency limits in vehicle activity and manual-control capacity. Based on these limits, a compensation algorithm has been developed for use in aircraft simulation at NASA Ames Research Center. For direct measurement of transport delays, a beam-splitter experiment is presented that accounts for the complete flight simulation environment. Values determined by this experiment are appropriate for use in the compensation algorithm. The algorithm extends the bandwidth of high-frequency flight simulation to well beyond that of normal pilot inputs. Within this bandwidth, the visual scene presentation manifests negligible gain distortion and phase lag. After a year of utilization, two minor exceptions to universal simulation applicability have been identified and subsequently resolved.

  6. Successful physician affiliations through fair compensation.

    PubMed

    Loudermilk, R C

    1995-03-01

    Appropriate physician compensation is essential if affiliations between physicians and healthcare organizations are to be successful. A physician's compensation should be based on market-specific data about compensation for his or her specialty, as well as on data about each physician's productivity. Healthcare organizations also must have a process for adjusting compensation based on performance and market changes and a process for ensuring equity between newly hired physicians and currently employed physicians. A systematic, data-driven approach to establishing physician compensation can help build a foundation for successful physician recruiting and relations. PMID:10146152

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

  8. New algorithms for binary wavefront optimization

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaolong; Kner, Peter

    2015-03-01

    Binary amplitude modulation promises to allow rapid focusing through strongly scattering media with a large number of segments due to the faster update rates of digital micromirror devices (DMDs) compared to spatial light modulators (SLMs). While binary amplitude modulation has a lower theoretical enhancement than phase modulation, the faster update rate should more than compensate for the difference - a factor of ?2 /2. Here we present two new algorithms, a genetic algorithm and a transmission matrix algorithm, for optimizing the focus with binary amplitude modulation that achieve enhancements close to the theoretical maximum. Genetic algorithms have been shown to work well in noisy environments and we show that the genetic algorithm performs better than a stepwise algorithm. Transmission matrix algorithms allow complete characterization and control of the medium but require phase control either at the input or output. Here we introduce a transmission matrix algorithm that works with only binary amplitude control and intensity measurements. We apply these algorithms to binary amplitude modulation using a Texas Instruments Digital Micromirror Device. Here we report an enhancement of 152 with 1536 segments (9.90%N) using a genetic algorithm with binary amplitude modulation and an enhancement of 136 with 1536 segments (8.9%N) using an intensity-only transmission matrix algorithm.

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

    NASA Technical Reports Server (NTRS)

    Blissit, J. A.

    1986-01-01

    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.

  10. A new phase error compensation method in digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Zhaomin; Qu, Weijuan; Wen, Yongfu; Yang, Fang; Asundi, Anand

    2015-03-01

    In this paper we present a new method to compensate for phase aberrations and image distortion with recording single digital hologram in digital holographic microscopy. In our method, tilt is removed from the abberrated phase map first. Then an area of interest (AOI) is generated by flood filled algorithm. By fitting AOI with discrete orthogonal Zernike polynomials, error phase map in the form of a series of Zernike polynomials is obtained. Final result can be calculated by subtracting the error phase map from the abberrated phase map. Through applying our method in microlens testing, phase aberrations and image distortion introduced by microscope objective are well suppressed.

  11. LPV Antiwindup Compensation for Enhanced Flight Control Performance

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  12. DC-Compensated Current Transformer.

    PubMed

    Ripka, Pavel; Draxler, Karel; Styblíková, Renata

    2016-01-01

    Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component. PMID:26805830

  13. Workers' Compensation Claims: Hidden Agendas

    PubMed Central

    Corbet, Kenneth

    1989-01-01

    Successful management of compensable occupational disorders requires an understanding of both the medical and social models of illness. In addition to the usual roles of medical diagnosis and treatment, the physician must assume a number of hidden roles, including assessing job hazards, arriving at an opinion of work-relatedness, identifying unrealistic expectations and factors that may delay recovery, and identifying as early as possible when vocational rehabilitation is necessary. As a central member of the claims management team, the practising physician can contribute meaningfully to the employee's successful return to the work-force. PMID:21248923

  14. Driver Compensation: Impairment or Improvement?

    PubMed

    Young, Richard A

    2015-12-01

    Strayer et al.'s conclusion that their "cognitive distraction scale" for auditory-vocal tasks indicates "significant impairments to driving" is not supported by their data. Additional analysis demonstrates that slower brake reaction times during auditory-vocal tasks were fully compensated for by longer following distances to the lead car. Naturalistic driving data demonstrate that cellular conversation decreases crash risk, the opposite of the article's assumption. Hence, the scale's internal and external validities for indicating driving impairment are highly questionable. PMID:26534851

  15. Charge amplifier with bias compensation

    DOEpatents

    Johnson, Gary W.

    2002-01-01

    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.

  16. Compensation issues tough to navigate

    SciTech Connect

    Madison, Alison L.

    2012-02-12

    Monthly economic diversity column for the Tri-City Herald - excerpt pasted below: Most industries out there are feeling the shift to a more educated, thus more empowered consumer. The legal field is no exception, which is why it's no surprise that lawsuits are on the rise. Today's society is one in which people are more aware than ever of their rights, and often equally convinced of their entitlements in a number of areas. For business owners, employees represent a major source of potential lawsuits. And compensation is an area of particular concern given that many complaints against employers revolve around it in some way.

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

    SciTech Connect

    Qi, Jinyi; Huesman, Ronald H.

    2002-07-03

    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.

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

    SciTech Connect

    Qi, Jinyi; Huesman, Ronald H.

    2002-07-01

    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.

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

    PubMed

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

    2014-01-01

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

  20. A Smart High Accuracy Silicon Piezoresistive Pressure Sensor Temperature Compensation System

    PubMed Central

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

    2014-01-01

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

  1. Wavefront curvature limitations and compensation to polar format processing for synthetic aperture radar images.

    SciTech Connect

    Doerry, Armin Walter

    2006-01-01

    Limitations on focused scene size for the Polar Format Algorithm (PFA) for Synthetic Aperture Radar (SAR) image formation are derived. A post processing filtering technique for compensating the spatially variant blurring in the image is examined. Modifications to this technique to enhance its robustness are proposed.

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

    SciTech Connect

    Weijer, Wilbert; Kinstle, Caroline M.

    2012-08-28

    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.

  3. Multi-bunch energy compensation

    SciTech Connect

    Ruth, R.D.

    1988-02-01

    To obtain a luminosity of 10{sup 34} cm{sup {minus}2} sec{sup {minus}1} in a TeV Linear Collider (TLC), it will probably be necessary to accelerate many bunches in one filling of the rf structure. This has the effect of extracting more energy from the structure and thus enhances the overall efficiency of the accelerator. However, this leads to many problems. First, the train bunches is subject to cummulative beam breakup transversely. This can be controlled by damping the transverse modes with slots in the irises coupled to waveguides. In addition, the energy of the bunches must be kept the same to high precision. For the fundamental mode, this entails adjusting the timing of the rf fill and also the bunch spacing. The higher longitudinal modes, although they do not induce instability, also may lead to bunch-to-bunch variations in energy. However, it also seems possible to damp these modes to cure this problem. Of course, there are also problems associated with damping a train of bunches in a damping ring. In this paper we discuss some of the issues of multi-bunch energy compensation. In the first two sections, we review some basics about energy extraction by a single bunch, and then, multi-bunch energy compensation is treated. We discuss various tolerance issues associated with deviations of amplitude and phase of the rf away from the ideal.

  4. Sewing algorithm

    NASA Astrophysics Data System (ADS)

    Booth, T. E.; Gubernatis, J. E.

    2009-04-01

    We present a procedure that in many cases enables the Monte Carlo sampling of states of a large system from the sampling of states of a smaller system. We illustrate this procedure, which we call the sewing algorithm, for sampling states from the transfer matrix of the two-dimensional Ising model.

  5. Algorithm development

    NASA Technical Reports Server (NTRS)

    Barth, Timothy J.; Lomax, Harvard

    1987-01-01

    The past decade has seen considerable activity in algorithm development for the Navier-Stokes equations. This has resulted in a wide variety of useful new techniques. Some examples for the numerical solution of the Navier-Stokes equations are presented, divided into two parts. One is devoted to the incompressible Navier-Stokes equations, and the other to the compressible form.

  6. CEO Compensation and Hospital Financial Performance

    PubMed Central

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

    2010-01-01

    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

  7. Vertical vibration analysis for elevator compensating sheave

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  8. Compensation of static deformation and vibrations of antenna arrays

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

  9. Motion-compensated speckle tracking via particle filtering

    NASA Astrophysics Data System (ADS)

    Liu, Lixin; Yagi, Shin-ichi; Bian, Hongyu

    2015-07-01

    Recently, an improved motion compensation method that uses the sum of absolute differences (SAD) has been applied to frame persistence utilized in conventional ultrasonic imaging because of its high accuracy and relative simplicity in implementation. However, high time consumption is still a significant drawback of this space-domain method. To seek for a more accelerated motion compensation method and verify if it is possible to eliminate conventional traversal correlation, motion-compensated speckle tracking between two temporally adjacent B-mode frames based on particle filtering is discussed. The optimal initial density of particles, the least number of iterations, and the optimal transition radius of the second iteration are analyzed from simulation results for the sake of evaluating the proposed method quantitatively. The speckle tracking results obtained using the optimized parameters indicate that the proposed method is capable of tracking the micromotion of speckle throughout the region of interest (ROI) that is superposed with global motion. The computational cost of the proposed method is reduced by 25% compared with that of the previous algorithm and further improvement is necessary.

  10. Compensation of low order aberrations with reflective beam shaping system

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  11. Log amplifier with pole-zero compensation

    DOEpatents

    Brookshier, W.

    1985-02-08

    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.

  12. Dispersion compensation for attosecond electron pulses

    SciTech Connect

    Hansen, Peter; Baumgarten, Cory; Batelaan, Herman; Centurion, Martin

    2012-08-20

    We propose a device to compensate for the dispersion of attosecond electron pulses. The device uses only static electric and magnetic fields and therefore does not require synchronization to the pulsed electron source. Analogous to the well-known optical dispersion compensator, an electron dispersion compensator separates paths by energy in space. Magnetic fields are used as the dispersing element, while a Wien filter is used for compensation of the electron arrival times. We analyze a device with a size of centimeters, which can be applied to ultrafast electron diffraction and microscopy, and fundamental studies.

  13. Log amplifier with pole-zero compensation

    DOEpatents

    Brookshier, William

    1987-01-01

    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.

  14. Computer compensation for cable signal degradations

    SciTech Connect

    Boyer, W B

    1987-12-01

    This paper describes two techniques for computing software cable compensation filters. These filters are used in correcting waveforms recorded from diagnostics on pulsed power accelerator. Applicable topics in continuous and discrete linear systems theory are reviewed. The first technique for computing a compensation function consists of recursively solving a discrete time domain convolution equation using measured undegraded and cable degraded pulses. The second tecnique computes the compensation function in the frequency domain using an analytical model of the cable frequency response and a constrained inverse filter. Detailed procedurs are described for computing cable compensation filters using an interactive data manipulation and hardware control program. 6 refs., 24 figs.

  15. Compensable back pain and migrants.

    PubMed

    Hewson, D; Halcrow, J; Brown, C S

    1987-09-21

    Ten years of cases of compensable back pain from a rehabilitation centre were reviewed for evidence that is relevant to the strongly negative stereotypes that are held commonly about migrant workers. The prevalence of migrant workers with back injuries was found to be similar to that in the occupations with higher accident liabilities in the surrounding municipalities. The relative proportion of musculoligamentous injuries and the more objectively confirmable back injuries was not related to the country of birth. Better predictors of treatment outcome were: the time that had elapsed between the injury and admission to the Centre; whether the referral was direct or indirect after the previous treatment; and the degree of fluency in English. It is concluded that the stereotypes that describe migrant workers as accident-prone or malingerers cannot be supported and that the vulnerability of migrant workers to the "accident-victim syndrome" can be accounted for without reference to ethnic characteristics. PMID:2957572

  16. Compensating for cold war cancers.

    PubMed

    Parascandola, Mark J

    2002-07-01

    Although the Cold War has ended, thousands of workers involved in nuclear weapons production are still living with the adverse health effects of working with radioactive materials, beryllium, and silica. After a series of court battles, the U.S. government passed the Energy Employees Occupational Illness Act in October 2000 to financially assist workers whose health has been compromised by these occupational exposures. Now work is underway to set out guidelines for determining which workers will be compensated. The National Institute for Occupational Safety and Health has been assigned the task of developing a model that can scientifically make these determinations, a heavy task considering the controversies that lie in estimating low-level radiation risks and the inadequate worker exposure records kept at many of the plants. PMID:12117658

  17. Motion errors and compensation possibilities

    NASA Astrophysics Data System (ADS)

    Hounam, David

    1992-08-01

    The synthetic aperture radar (SAR) technique relies on knowledge of the relative motion between the sensor and the target. If the flight path of the sensor is not accurately known or the SAR processor is limited in its ability to take the flight data into account, the SAR image will be degraded. Motion errors are particularly critical for SAR sensors on small, low-flying aircraft, due to turbulence, and where high spatial resolution is required. The lecture discusses the effects of motion errors on image quality and the requirements on the sensor and processor to compensate for motion errors. The DLR airborne sensor, E-SAR, and associated image processor will be used as examples. Techniques using a priori knowledge of the flight path from independent sensors, e.g., inertial navigation systems (INS), and by extracting the flight data from the SAR data, e.g., autofocus and reflectivity displacement method (RDM), are treated.

  18. Iterative motion compensation approach for ultrasonic thermal imaging

    NASA Astrophysics Data System (ADS)

    Fleming, Ioana; Hager, Gregory; Guo, Xiaoyu; Kang, Hyun Jae; Boctor, Emad

    2015-03-01

    As thermal imaging attempts to estimate very small tissue motion (on the order of tens of microns), it can be negatively influenced by signal decorrelation. Patient's breathing and cardiac cycle generate shifts in the RF signal patterns. Other sources of movement could be found outside the patient's body, like transducer slippage or small vibrations due to environment factors like electronic noise. Here, we build upon a robust displacement estimation method for ultrasound elastography and we investigate an iterative motion compensation algorithm, which can detect and remove non-heat induced tissue motion at every step of the ablation procedure. The validation experiments are performed on laboratory induced ablation lesions in ex-vivo tissue. The ultrasound probe is either held by the operator's hand or supported by a robotic arm. We demonstrate the ability to detect and remove non-heat induced tissue motion in both settings. We show that removing extraneous motion helps unmask the effects of heating. Our strain estimation curves closely mirror the temperature changes within the tissue. While previous results in the area of motion compensation were reported for experiments lasting less than 10 seconds, our algorithm was tested on experiments that lasted close to 20 minutes.

  19. Optimized Reactive Power Compensation Using Fuzzy Logic Controller

    NASA Astrophysics Data System (ADS)

    George, S.; Mini, K. N.; Supriya, K.

    2015-03-01

    Reactive power flow in a long transmission line plays a vital role in power transfer capability and voltage stability in power system. Traditionally, shunt connected compensators are used to control reactive power in long transmission line. Thyristor controlled reactor is used to control reactive power under lightly loaded condition. By controlling firing angle of thyristor, it is possible to control reactive power in the transmission lines. However, thyristor controlled reactor will inject harmonic current into the system. An attempt to reduce reactive power injection will increase harmonic distortion in the line current and vice versa. Thus, there is a trade-off between reactive power injection and harmonics in current. By optimally controlling the reactive power injection, harmonics in current can be brought within the specified limit. In this paper, a Fuzzy Logic Controller is implemented to obtain optimal control of reactive power of the compensator to maintain voltage and harmonic in current within the limits. An algorithm which optimizes the firing angle in each fuzzy subset by calculating the rank of feasible firing angles is proposed for the construction of rules in Fuzzy Logic Controller. The novelty of the algorithm is that it uses a simple error formula for the calculation of the rank of the feasible firing angles in each fuzzy subset.

  20. Accuracy of numerically produced compensators.

    PubMed

    Thompson, H; Evans, M D; Fallone, B G

    1999-01-01

    A feasibility study is performed to assess the utility of a computer numerically controlled (CNC) mill to produce compensating filters for conventional clinical use and for the delivery of intensity-modulated beams. A computer aided machining (CAM) software is used to assist in the design and construction of such filters. Geometric measurements of stepped and wedged surfaces are made to examine the accuracy of surface milling. Molds are milled and filled with molten alloy to produce filters, and both the molds and filters are examined for consistency and accuracy. Results show that the deviation of the filter surfaces from design does not exceed 1.5%. The effective attenuation coefficient is measured for CadFree, a cadmium-free alloy, in a 6 MV photon beam. The effective attenuation coefficients at the depth of maximum dose (1.5 cm) and at 10 cm in solid water phantom are found to be 0.546 cm-1 and 0.522 cm-1, respectively. Further attenuation measurements are made with Cerrobend to assess the variations of the effective attenuation coefficient with field size and source-surface distance. The ability of the CNC mill to accurately produce surfaces is verified with dose profile measurements in a 6 MV photon beam. The test phantom is composed of a 10 degrees polystyrene wedge and a 30 degrees polystyrene wedge, presenting both a sharp discontinuity and sloped surfaces. Dose profiles, measured at the depth of compensation (10 cm) beneath the test phantom and beneath a flat phantom, are compared to those produced by a commercial treatment planning system. Agreement between measured and predicted profiles is within 2%, indicating the viability of the system for filter production. PMID:10100166

  1. Isometric Immersions and Compensated Compactness

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  2. Image compensation using wavelet transform for tilt servo control in holographic data storage system

    NASA Astrophysics Data System (ADS)

    Kim, Jang Hyun; Yang, Hyunseok

    2015-09-01

    A holographic data storage system is very important in the division of a mass storage device. In this regard, tilt servo control is the main problem in the study of holographic data storage system. Tracking servo and tilt servo control are very important research area in holographic data storage system. In this paper, we propose two algorithms. The first algorithm is image compensation using the wavelet transform method and the second algorithm is intelligent servo control using fuzzy rules for the exact tilt control in the holographic data storage system. We need to obtain a good pattern in binary data using a CMOS camera. We have developed two step-by-step operations. Firstly, to obtain exact image data, image data compensation carried out by the wavelet transform method. Finally, we have realized an intelligence control model using fuzzy rules, which was generated by a subtractive clustering algorithm. Therefore, we control radial and tangential tilt servo control using fuzzy rules in a holographic data storage system and perform image data compensation by the wavelet transform method. Our system does not require responses in the tilt servo control system. Therefore, this system has the advantage terms of time. Consequently, the practical pattern of tilt servo control was found by an intelligence algorithm through image processing in the holographic data storage system.

  3. Decision-aided sampling frequency offset compensation for reduced-guard-interval coherent optical OFDM systems.

    PubMed

    Wang, Wei; Zhuge, Qunbi; Morsy-Osman, Mohamed; Gao, Yuliang; Xu, Xian; Chagnon, Mathieu; Qiu, Meng; Hoang, Minh Thang; Zhang, Fangyuan; Li, Rui; Plant, David V

    2014-11-01

    We propose a decision-aided algorithm to compensate the sampling frequency offset (SFO) between the transmitter and receiver for reduced-guard-interval (RGI) coherent optical (CO) OFDM systems. In this paper, we first derive the cyclic prefix (CP) requirement for preventing OFDM symbols from SFO induced inter-symbol interference (ISI). Then we propose a new decision-aided SFO compensation (DA-SFOC) algorithm, which shows a high SFO tolerance and reduces the CP requirement. The performance of DA-SFOC is numerically investigated for various situations. Finally, the proposed algorithm is verified in a single channel 28 Gbaud polarization division multiplexing (PDM) RGI CO-OFDM experiment with QPSK, 8 QAM and 16 QAM modulation formats, respectively. Both numerical and experimental results show that the proposed DA-SFOC method is highly robust against the standard SFO in optical fiber transmission. PMID:25401902

  4. Refractive index compensation in over-determined interferometric systems.

    PubMed

    Lazar, Josef; Holá, Miroslava; Číp, Ondřej; Čížek, Martin; Hrabina, Jan; Buchta, Zdeněk

    2012-01-01

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

  5. Refractive Index Compensation in Over-Determined Interferometric Systems

    PubMed Central

    Lazar, Josef; Holá, Miroslava; Číp, Ondřej; Čížek, Martin; Hrabina, Jan; Buchta, Zdeněk

    2012-01-01

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

  6. 38 CFR 3.351 - Special monthly dependency and indemnity compensation, death compensation, pension and spouse's...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Special monthly dependency and indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION...

  7. 38 CFR 3.351 - Special monthly dependency and indemnity compensation, death compensation, pension and spouse's...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Special monthly dependency and indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION...

  8. 38 CFR 3.351 - Special monthly dependency and indemnity compensation, death compensation, pension and spouse's...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Special monthly dependency and indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION...

  9. 38 CFR 3.351 - Special monthly dependency and indemnity compensation, death compensation, pension and spouse's...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Special monthly dependency and indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION...

  10. 38 CFR 3.351 - Special monthly dependency and indemnity compensation, death compensation, pension and spouse's...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Special monthly dependency and indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION...

  11. Atmospheric Models for Aerocapture

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    There are eight destinations in the solar System with sufficient atmosphere for aerocapture to be a viable aeroassist option - Venus, Earth, Mars, Jupiter, Saturn and its moon Titan, Uranus, and Neptune. Engineering-level atmospheric models for four of these targets (Earth, Mars, Titan, and Neptune) have been developed for NASA to support systems analysis studies of potential future aerocapture missions. Development of a similar atmospheric model for Venus has recently commenced. An important capability of all of these models is their ability to simulate quasi-random density perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithm, and for thermal systems design. Similarities and differences among these atmospheric models are presented, with emphasis on the recently developed Neptune model and on planned characteristics of the Venus model. Example applications for aerocapture are also presented and illustrated. Recent updates to the Titan atmospheric model are discussed, in anticipation of applications for trajectory and atmospheric reconstruct of Huygens Probe entry at Titan.

  12. The GODFIT Direct Fitting Algorithm: A New Approach for Total Ozone Retrieval From GOME

    NASA Astrophysics Data System (ADS)

    Spurr, R. J.; van Roozendael, M.; Lambert, J.; Fayt, C.

    2004-05-01

    We present a new Direct Fitting algorithm (GODFIT) for the retrieval of total ozone amounts from nadir viewing remote sensing spectrometers (such as GOME, SCIAMACHY, OMI and GOME-2) which take earthshine measurements in the UV ozone Huggins bands. The algorithm is designed for direct comparison with measurements, and all radiative transfer (RT) calculations are done from scratch. We use the linearized RT model LIDORT, which has a single-call facility for simultaneous computations of radiances and fast analytic calculations of Jacobians with respect to surface and atmospheric properties. RT calculations require an input profile of ozone partial columns; we use a column-classified ozone profile climatology (the TOMS Version 8 data set) which provides a unique map between the fitted total column and the input RT profile. To compensate for lack of knowledge of tropospheric aerosol, we perform calculations in a Rayleigh atmosphere and fit for the surface albedo as an internal closure parameter; the algorithm is less sensitive to the presence of aerosol than DOAS-AMF algorithms customarily used for this retrieval. The Ring effect is important in the UV, and GODFIT contains a new treatment for the correction of interference effects due to the filling-in of ozone molecular features by inelastic rotational Raman scattering. The algorithm is flexible and direct, and operates without the need for extensive look-up tables. The algorithm was applied to a subset of some 2000 GOME orbits used in validation studies for the total ozone product. The algorithm can process one orbit (~2000 scenes) in under half an hour. Results were compared with ground data from a well-documented network of surface stations, with TOMS total ozone measurements (Version 8), and also with GOME-derived columns from the latest version of the GDP (operational GOME Data Processor DOAS-type total ozone algorithm). With the new results, previously observed seasonality and solar angle dependencies are greatly reduced or even eliminated in most latitudes and time zones (the exception is Antartica in the Austral Spring). New results for GOME total ozone are now of comparable accuracy to ground-based data, and in this regard, the 8-year GOME ozone data record will become suitable for trend analysis and climate studies in the near future. This application for GOME is the first proof of the direct fitting concept, and the method shows great potential for further applications in hyperspectral remote sensing.

  13. 33 CFR 136.223 - Compensation allowable.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.223 Section 136.223 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  14. 33 CFR 136.235 - Compensation allowable.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Compensation allowable. 136.235 Section 136.235 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  15. 33 CFR 136.241 - Compensation allowable.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Compensation allowable. 136.241 Section 136.241 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  16. 33 CFR 136.223 - Compensation allowable.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Compensation allowable. 136.223 Section 136.223 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  17. 33 CFR 136.205 - Compensation allowable.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Compensation allowable. 136.205 Section 136.205 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  18. 33 CFR 136.229 - Compensation allowable.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.229 Section 136.229 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  19. 33 CFR 136.241 - Compensation allowable.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Compensation allowable. 136.241 Section 136.241 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  20. 33 CFR 136.229 - Compensation allowable.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Compensation allowable. 136.229 Section 136.229 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  1. 33 CFR 136.217 - Compensation allowable.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Compensation allowable. 136.217 Section 136.217 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  2. 33 CFR 136.211 - Compensation allowable.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Compensation allowable. 136.211 Section 136.211 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  3. 33 CFR 136.113 - Other compensation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Other compensation. 136.113 Section 136.113 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  4. 33 CFR 136.113 - Other compensation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Other compensation. 136.113 Section 136.113 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  5. 33 CFR 136.241 - Compensation allowable.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.241 Section 136.241 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  6. 33 CFR 136.223 - Compensation allowable.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Compensation allowable. 136.223 Section 136.223 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  7. 33 CFR 136.223 - Compensation allowable.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Compensation allowable. 136.223 Section 136.223 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  8. 33 CFR 136.235 - Compensation allowable.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Compensation allowable. 136.235 Section 136.235 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  9. 33 CFR 136.205 - Compensation allowable.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Compensation allowable. 136.205 Section 136.205 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  10. 33 CFR 136.217 - Compensation allowable.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Compensation allowable. 136.217 Section 136.217 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  11. 33 CFR 136.235 - Compensation allowable.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Compensation allowable. 136.235 Section 136.235 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  12. 33 CFR 136.211 - Compensation allowable.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Compensation allowable. 136.211 Section 136.211 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  13. 33 CFR 136.241 - Compensation allowable.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Compensation allowable. 136.241 Section 136.241 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  14. 33 CFR 136.235 - Compensation allowable.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Compensation allowable. 136.235 Section 136.235 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  15. 33 CFR 136.241 - Compensation allowable.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Compensation allowable. 136.241 Section 136.241 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  16. 33 CFR 136.229 - Compensation allowable.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Compensation allowable. 136.229 Section 136.229 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  17. 33 CFR 136.113 - Other compensation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Other compensation. 136.113 Section 136.113 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  18. 33 CFR 136.211 - Compensation allowable.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.211 Section 136.211 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  19. 33 CFR 136.205 - Compensation allowable.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.205 Section 136.205 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  20. 33 CFR 136.217 - Compensation allowable.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Compensation allowable. 136.217 Section 136.217 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  1. 33 CFR 136.211 - Compensation allowable.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Compensation allowable. 136.211 Section 136.211 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  2. 33 CFR 136.205 - Compensation allowable.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Compensation allowable. 136.205 Section 136.205 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  3. 33 CFR 136.229 - Compensation allowable.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Compensation allowable. 136.229 Section 136.229 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  4. 33 CFR 136.217 - Compensation allowable.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.217 Section 136.217 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  5. 33 CFR 136.235 - Compensation allowable.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Compensation allowable. 136.235 Section 136.235 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  6. 47 CFR 32.24 - Compensated absences.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Compensated absences. 32.24 Section 32.24 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES General Instructions § 32.24 Compensated absences. (a)...

  7. A New Look at Shunt Compensation.

    SciTech Connect

    Kimbark, Edward Wilson

    1983-01-01

    This paper introduces the concept that the surge impedance of a transmission line can be rapidly controlled by shunt compensation to make the corresponding surge impedance loading always equal to the actual loading. So doing prevents normal-frequency overvoltages and limits undervoltages. On a doublecircuit line it permits the compensation to be employed on either circuit when the other circuit is disabled.

  8. 12 CFR 2.5 - Bank compensation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... compensation. (a) Nothing contained in this part prohibits a bank employee, officer, director, or principal... premises, employees, or good will. However, the employee, officer, director, or principal shareholder shall... compensation in recognition of the role played by its personnel, premises, and good will in credit...

  9. 16 CFR 1105.11 - Compensable costs.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Compensable costs. 1105.11 Section 1105.11 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS CONTRIBUTIONS TO COSTS OF PARTICIPANTS IN DEVELOPMENT OF CONSUMER PRODUCT SAFETY STANDARDS 1105.11 Compensable costs. The Commission may...

  10. 33 CFR 136.217 - Compensation allowable.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Compensation allowable. 136.217 Section 136.217 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  11. 33 CFR 136.113 - Other compensation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Other compensation. 136.113 Section 136.113 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  12. 33 CFR 136.229 - Compensation allowable.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Compensation allowable. 136.229 Section 136.229 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  13. 33 CFR 136.205 - Compensation allowable.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Compensation allowable. 136.205 Section 136.205 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  14. 33 CFR 136.113 - Other compensation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Other compensation. 136.113 Section 136.113 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  15. 33 CFR 136.211 - Compensation allowable.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Compensation allowable. 136.211 Section 136.211 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  16. 33 CFR 136.223 - Compensation allowable.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Compensation allowable. 136.223 Section 136.223 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE POLLUTION FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND;...

  17. 12 CFR 2.5 - Bank compensation.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Bank compensation. 2.5 Section 2.5 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE 2.5 Bank compensation. (a) Nothing contained in this part prohibits a bank employee, officer, director, or...

  18. 48 CFR 752.7007 - Personnel compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Personnel compensation. 752.7007 Section 752.7007 Federal Acquisition Regulations System AGENCY FOR INTERNATIONAL DEVELOPMENT CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Texts of USAID Contract Clauses 752.7007 Personnel compensation. The following...

  19. Displacement Compensation of Temperature Probe Data

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  20. 16 CFR 16.16 - Compensation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Compensation. 16.16 Section 16.16 Commercial Practices FEDERAL TRADE COMMISSION ORGANIZATION, PROCEDURES AND RULES OF PRACTICE ADVISORY COMMITTEE MANAGEMENT 16.16 Compensation. (a) Committee members. Unless otherwise provided by law, the...

  1. 12 CFR 2.5 - Bank compensation.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Bank compensation. 2.5 Section 2.5 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE 2.5 Bank compensation. (a) Nothing contained in this part prohibits a bank employee, officer, director, or...

  2. 12 CFR 2.5 - Bank compensation.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Bank compensation. 2.5 Section 2.5 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE 2.5 Bank compensation. (a) Nothing contained in this part prohibits a bank employee, officer, director, or...

  3. 12 CFR 2.5 - Bank compensation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Bank compensation. 2.5 Section 2.5 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE 2.5 Bank compensation. (a) Nothing contained in this part prohibits a bank employee, officer, director, or...

  4. 30 CFR 90.103 - Compensation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... HEALTH STANDARDS-COAL MINERS WHO HAVE EVIDENCE OF THE DEVELOPMENT OF PNEUMOCONIOSIS Dust Standards, Rights of Part 90 Miners 90.103 Compensation. (a) The operator shall compensate each Part 90 miner at not less than the regular rate of pay received by that miner immediately before exercising the...

  5. The Compensation of College and University Presidents.

    ERIC Educational Resources Information Center

    Pfeffer, Jeffrey; Ross, Jerry

    1988-01-01

    In a study of the compensation of more than 600 college and university presidents, both individual and institutional characteristics were found to predict salary. The overall results are consistent with both functional theories of compensation and perspectives emphasizing the attribution of effectiveness to leaders. (MSE)

  6. 44 CFR 295.21 - Allowable compensation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... not receive compensation for any injury or damage that is not compensable under the Federal Tort... measures that will reduce the property's vulnerability to the future risk of wildfire, flood or other... assistance under the Stafford Act) for damage to the structure and lot. The Claimant must obtain...

  7. 44 CFR 295.21 - Allowable compensation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... not receive compensation for any injury or damage that is not compensable under the Federal Tort... measures that will reduce the property's vulnerability to the future risk of wildfire, flood or other... assistance under the Stafford Act) for damage to the structure and lot. The Claimant must obtain...

  8. 44 CFR 295.21 - Allowable compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... not receive compensation for any injury or damage that is not compensable under the Federal Tort... measures that will reduce the property's vulnerability to the future risk of wildfire, flood or other... assistance under the Stafford Act) for damage to the structure and lot. The Claimant must obtain...

  9. 44 CFR 295.21 - Allowable compensation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 44 Emergency Management and Assistance 1 2013-10-01 2013-10-01 false Allowable compensation. 295.21 Section 295.21 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY CERRO GRANDE FIRE ASSISTANCE CERRO GRANDE FIRE ASSISTANCE Compensation Available Under the CGFAA § 295.21 Allowable...

  10. 45 CFR 1607.5 - Compensation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 4 2014-10-01 2014-10-01 false Compensation. 1607.5 Section 1607.5 Public Welfare Regulations Relating to Public Welfare (Continued) LEGAL SERVICES CORPORATION GOVERNING BODIES § 1607.5 Compensation. (a) While serving on the governing body of a recipient, no attorney member shall...

  11. 45 CFR 1607.5 - Compensation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 4 2011-10-01 2011-10-01 false Compensation. 1607.5 Section 1607.5 Public Welfare Regulations Relating to Public Welfare (Continued) LEGAL SERVICES CORPORATION GOVERNING BODIES § 1607.5 Compensation. (a) While serving on the governing body of a recipient, no attorney member shall...

  12. 45 CFR 1607.5 - Compensation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Compensation. 1607.5 Section 1607.5 Public Welfare Regulations Relating to Public Welfare (Continued) LEGAL SERVICES CORPORATION GOVERNING BODIES § 1607.5 Compensation. (a) While serving on the governing body of a recipient, no attorney member shall...

  13. 45 CFR 1607.5 - Compensation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 4 2013-10-01 2013-10-01 false Compensation. 1607.5 Section 1607.5 Public Welfare Regulations Relating to Public Welfare (Continued) LEGAL SERVICES CORPORATION GOVERNING BODIES § 1607.5 Compensation. (a) While serving on the governing body of a recipient, no attorney member shall...

  14. 45 CFR 1607.5 - Compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 4 2012-10-01 2012-10-01 false Compensation. 1607.5 Section 1607.5 Public Welfare Regulations Relating to Public Welfare (Continued) LEGAL SERVICES CORPORATION GOVERNING BODIES § 1607.5 Compensation. (a) While serving on the governing body of a recipient, no attorney member shall...

  15. 28 CFR 345.54 - Overtime compensation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Overtime compensation. 345.54 Section 345.54 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE FEDERAL PRISON INDUSTRIES (FPI) INMATE WORK PROGRAMS Inmate Pay and Benefits 345.54 Overtime compensation. An...

  16. 28 CFR 345.54 - Overtime compensation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Overtime compensation. 345.54 Section 345.54 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE FEDERAL PRISON INDUSTRIES (FPI) INMATE WORK PROGRAMS Inmate Pay and Benefits 345.54 Overtime compensation. An...

  17. 28 CFR 345.54 - Overtime compensation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Overtime compensation. 345.54 Section 345.54 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE FEDERAL PRISON INDUSTRIES (FPI) INMATE WORK PROGRAMS Inmate Pay and Benefits 345.54 Overtime compensation. An...

  18. 28 CFR 345.54 - Overtime compensation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Overtime compensation. 345.54 Section 345.54 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE FEDERAL PRISON INDUSTRIES (FPI) INMATE WORK PROGRAMS Inmate Pay and Benefits 345.54 Overtime compensation. An...

  19. 28 CFR 345.54 - Overtime compensation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Overtime compensation. 345.54 Section 345.54 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE FEDERAL PRISON INDUSTRIES (FPI) INMATE WORK PROGRAMS Inmate Pay and Benefits 345.54 Overtime compensation. An...

  20. Chromatic dispersion and nonlinear phase noise compensation based on KLMS method

    NASA Astrophysics Data System (ADS)

    Nouri, Mahdi; Shayesteh, Mahrokh G.; Farhangian, Nooshin

    2015-09-01

    In this study, kernel least mean square (KLMS) algorithm with fractionally spaced equalizing structure is proposed for electrical compensation of chromatic dispersion (CD) and nonlinear phase noise (NLPN) in a dual polarization optical communications system with coherent detection. We consider single mode fiber channel. At the receiver, the additive optical noise is represented as additive white Gaussian noise. Phase modification is utilized at high signal powers to maintain the validity of Gaussian model of noise. We consider QAM and PSK modulations and evaluate the performance of the proposed method in terms of error rate, phase error, and error vector magnitude (EVM). The results are obtained in both linear and nonlinear regimes. In the linear region, the KLMS algorithm can compensate CD and NLPN effectively and outperforms the existing compensation methods such as LMS, minimum mean square error (MMSE), and time domain FIR filter. In nonlinear regime, where the input power is higher, NLPN is stronger which results in compensation performance degradation. However, KLMS still achieves better results than the above algorithms.

  1. Physician compensation based on performance appraisal.

    PubMed

    Permut, R

    1990-01-01

    Physician compensation in a group practice setting has long been a subject of discussion and time investment, both on the part of managers and physicians. With a changing external environment, including Medicare fee freeze, capitation, and other forms of discounted, contractual medicine, former income distribution plans may not serve group practices well anymore. The ability of group practices to attract, retain, and develop physicians is at least partially dependent upon physician compensation structure. Taking into consideration marketplace characteristics for different specialties and offering equity in the compensation process are important features of any income distribution plan. This paper emphasizes a longstanding business tool, performance appraisal, which may be a key future determinant of physician compensation. The utilization of performance appraisal in establishing physician compensation is discussed and a sample performance appraisal instrument is included as a model. PMID:10105259

  2. The National Vaccine Injury Compensation Program.

    PubMed

    Cook, Katherine M; Evans, Geoffrey

    2011-05-01

    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

  3. Dosage Compensation of the Sex Chromosomes

    PubMed Central

    Disteche, Christine M.

    2013-01-01

    Differentiated sex chromosomes evolved because of suppressed recombination once sex became genetically controlled. In XX/XY and ZZ/ZW systems, the heterogametic sex became partially aneuploid after degeneration of the Y or W. Often, aneuploidy causes abnormal levels of gene expression throughout the entire genome. Dosage compensation mechanisms evolved to restore balanced expression of the genome. These mechanisms include upregulation of the heterogametic chromosome as well as repression in the homogametic sex. Remarkably, strategies for dosage compensation differ between species. In organisms where more is known about molecular mechanisms of dosage compensation, specific protein complexes containing noncoding RNAs are targeted to the X chromosome. In addition, the dosage-regulated chromosome often occupies a specific nuclear compartment. Some genes escape dosage compensation, potentially resulting in sex-specific differences in gene expression. This review focuses on dosage compensation in mammals, with comparisons to fruit flies, nematodes, and birds. PMID:22974302

  4. Compensation of non-ideal beam splitter polarization distortion effect in Michelson interferometer

    NASA Astrophysics Data System (ADS)

    Liu, Yeng-Cheng; Lo, Yu-Lung; Liao, Chia-Chi

    2016-02-01

    A composite optical structure consisting of two quarter-wave plates and a single half-wave plate is proposed for compensating for the polarization distortion induced by a non-ideal beam splitter in a Michelson interferometer. In the proposed approach, the optimal orientations of the optical components within the polarization compensator are determined using a genetic algorithm (GA) such that the beam splitter can be treated as a free-space medium and modeled using a unit Mueller matrix accordingly. Two implementations of the proposed polarization controller are presented. In the first case, the compensator is placed in the output arm of Michelson interferometer such that the state of polarization of the interfered output light is equal to that of the input light. However, in this configuration, the polarization effects induced by the beam splitter in the two arms of the interferometer structure cannot be separately addressed. Consequently, in the second case, compensator structures are placed in the Michelson interferometer for compensation on both the scanning and reference beams. The practical feasibility of the proposed approach is introduced by considering a Mueller polarization-sensitive (PS) optical coherence tomography (OCT) structure with three polarization controllers in the input, reference and sample arms, respectively. In general, the results presented in this study show that the proposed polarization controller provides an effective and experimentally-straightforward means of compensating for the polarization distortion effects induced by the non-ideal beam splitters in Michelson interferometers and Mueller PS-OCT structures.

  5. An Efficient Adaptive Angle-Doppler Compensation Approach for Non-Sidelooking Airborne Radar STAP

    PubMed Central

    Shen, Mingwei; Yu, Jia; Wu, Di; Zhu, Daiyin

    2015-01-01

    In this study, the effects of non-sidelooking airborne radar clutter dispersion on space-time adaptive processing (STAP) is considered, and an efficient adaptive angle-Doppler compensation (EAADC) approach is proposed to improve the clutter suppression performance. In order to reduce the computational complexity, the reduced-dimension sparse reconstruction (RDSR) technique is introduced into the angle-Doppler spectrum estimation to extract the required parameters for compensating the clutter spectral center misalignment. Simulation results to demonstrate the effectiveness of the proposed algorithm are presented. PMID:26053755

  6. An Efficient Adaptive Angle-Doppler Compensation Approach for Non-Sidelooking Airborne Radar STAP.

    PubMed

    Shen, Mingwei; Yu, Jia; Wu, Di; Zhu, Daiyin

    2015-01-01

    In this study, the effects of non-sidelooking airborne radar clutter dispersion on space-time adaptive processing (STAP) is considered, and an efficient adaptive angle-Doppler compensation (EAADC) approach is proposed to improve the clutter suppression performance. In order to reduce the computational complexity, the reduced-dimension sparse reconstruction (RDSR) technique is introduced into the angle-Doppler spectrum estimation to extract the required parameters for compensating the clutter spectral center misalignment. Simulation results to demonstrate the effectiveness of the proposed algorithm are presented. PMID:26053755

  7. Compensation of the Effect of a Detector Solenoid on the Beam Size in the ILC

    SciTech Connect

    Seletskiy, S.; /SLAC

    2007-07-06

    In the International Linear Collider (ILC) [1] the colliding beams must be focused to the nanometer size in order to reach the desired luminosity. The method of Weak Antisolenoid is used for the compensation of the effect of the Detector Solenoid on the beam size [2], [3]. The studies of this method require the computer simulation of the charged particle's kinematics in the arbitrarily distributed solenoidal, dipole, quadrupole and higher multipole fields. We suggest the mathematical algorithm that allows to optimize parameters of antisolenoid for different configurations of Final Focus magnets and to compensate parasitic effects of the Detector Solenoid on the beam.

  8. A New Technique for Compensating Joint Limits in a Robot Manipulator

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

  10. Harmonic-based gain compensation method in optic sensors with separate light paths.

    PubMed

    Perciante, César Daniel; Ferrari, José A; Garbusi, Eugenio

    2003-06-10

    We describe a method for the compensation of gain unbalance in optical sensors with separate light path that involve two separate detection and conditioning electronic devices. The method is based on the digital measurement of harmonics of the output intensities from each path by means of the fast Fourier transform algorithm. The quotient of the amplitude of harmonics allows us to calculate the unbalance between paths and to compensate for it. In particular, this method can be applied electric power and current sensors that use Faraday and Pockels cells to measure current and voltage, respectively. PMID:12816322

  11. 28 CFR 301.318 - Civilian compensation laws distinguished.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.318 Civilian compensation laws distinguished. The Inmate Accident Compensation system is not obligated to.... Awards made under the provisions of the Inmate Accident Compensation procedure differ from awards...

  12. 28 CFR 301.318 - Civilian compensation laws distinguished.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.318 Civilian compensation laws distinguished. The Inmate Accident Compensation system is not obligated to.... Awards made under the provisions of the Inmate Accident Compensation procedure differ from awards...

  13. 28 CFR 301.318 - Civilian compensation laws distinguished.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.318 Civilian compensation laws distinguished. The Inmate Accident Compensation system is not obligated to.... Awards made under the provisions of the Inmate Accident Compensation procedure differ from awards...

  14. 28 CFR 301.318 - Civilian compensation laws distinguished.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death 301.318 Civilian compensation laws distinguished. The Inmate Accident Compensation system is not obligated to.... Awards made under the provisions of the Inmate Accident Compensation procedure differ from awards...

  15. 20 CFR 10.15 - May compensation rights be waived?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true May compensation rights be waived? 10.15 Section 10.15 Employees' Benefits OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF LABOR FEDERAL EMPLOYEES' COMPENSATION ACT CLAIMS FOR COMPENSATION UNDER THE FEDERAL EMPLOYEES' COMPENSATION ACT, AS AMENDED General Provisions Rights and Penalties...

  16. 20 CFR 10.15 - May compensation rights be waived?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false May compensation rights be waived? 10.15 Section 10.15 Employees' Benefits OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF LABOR FEDERAL EMPLOYEES' COMPENSATION ACT CLAIMS FOR COMPENSATION UNDER THE FEDERAL EMPLOYEES' COMPENSATION ACT, AS AMENDED General Provisions Rights and...

  17. 28 CFR 104.21 - Filing for compensation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Filing for compensation. 104.21 Section 104.21 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) SEPTEMBER 11TH VICTIM COMPENSATION FUND OF 2001 Filing for Compensation; Application for Advance Benefits 104.21 Filing for compensation. (a) Compensation form; filing. Except...

  18. Self Organization in Compensated Semiconductors

    NASA Astrophysics Data System (ADS)

    Berezin, Alexander A.

    2004-03-01

    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.

  19. Compensation Following Bilateral Vestibular Damage

    PubMed Central

    McCall, Andrew A.; Yates, Bill J.

    2011-01-01

    Bilateral loss of vestibular inputs affects far fewer patients than unilateral inner ear damage, and thus has been understudied. In both animal subjects and human patients, bilateral vestibular hypofunction (BVH) produces a variety of clinical problems, including impaired balance control, inability to maintain stable blood pressure during postural changes, difficulty in visual targeting of images, and disturbances in spatial memory and navigational performance. Experiments in animals have shown that non-labyrinthine inputs to the vestibular nuclei are rapidly amplified following the onset of BVH, which may explain the recovery of postural stability and orthostatic tolerance that occurs within 10?days. However, the loss of the vestibulo-ocular reflex and degraded spatial cognition appear to be permanent in animals with BVH. Current concepts of the compensatory mechanisms in humans with BVH are largely inferential, as there is a lack of data from patients early in the disease process. Translation of animal studies of compensation for BVH into therapeutic strategies and subsequent application in the clinic is the most likely route to improve treatment. In addition to physical therapy, two types of prosthetic devices have been proposed to treat individuals with bilateral loss of vestibular inputs: those that provide tactile stimulation to indicate body position in space, and those that deliver electrical stimuli to branches of the vestibular nerve in accordance with head movements. The relative efficacy of these two treatment paradigms, and whether they can be combined to facilitate recovery, is yet to be ascertained. PMID:22207864

  20. Bjerknes-like Compensation Between Eddy Components of Meridional Heat Transport in the Wintertime North Pacific

    NASA Astrophysics Data System (ADS)

    Bishop, S. P.; Bryan, F.; Small, R. J.

    2014-12-01

    Observational and model evidence has been mounting that mesoscale eddies play an important role in air-sea interaction in the vicinity of Western Boundary Currents. What has been less clear is the interplay between oceanic and atmospheric meridional eddy heat transport (MEHT). It is first shown using a high-resolution fully-coupled climate simulation of the Community Earth System Model (CESM) that variability in the North Pacific, particularly in the Kuroshio Extension region, matches observations with similar mechanisms; the Pacific Decadal Oscillation (PDO) leads Kuroshio Extension variability with a ~3-4 year lag. It is then shown that there is a compensation of ~0.1 PW between wintertime atmospheric and oceanic MEHT on decadal time scales in the North Pacific. This compensation has characteristics of Bjerknes compensation and is tied to the mesoscale eddy activity in Kuroshio Extension region. During weakly meandering ("stable") states there is the persistence of equatorward oceanic MEHT south of the jet and enhanced wintertime surface heat fluxes (SHFs). The atmospheric vertically-integrated meridional eddy heat flux is 22% larger compared to the mean with a maximum increase in MEHT of 0.11+/-0.03 PW. When the Kuroshio Extension is in a strongly meandering ("unstable") state oceanic MEHT is enhanced by a maximum of 0.07+/-0.02 PW with a subsequent reduction in wintertime ocean-to-atmosphere SHFs and atmospheric MEHT.