Sample records for atmospheric compensation algorithm

  1. Atmospheric compensation in free space optical communication with simulated annealing algorithm

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    As we know that the conventional adaptive optics (AO) systems can compensate atmospheric turbulence in free space optical (FSO) communication system. Since in strong scintillation conditions, wave-front measurements based on phase-conjugation principle are undesired. A novel global optimization simulated annealing (SA) algorithm is proposed in this paper to compensate wave-front aberration. With global optimization characteristics, SA algorithm is better than stochastic parallel gradient descent (SPGD) and other algorithms that already exist. Related simulations are conducted and the results show that the SA algorithm can significantly improve performance in FSO communication system and is better than SPGD algorithm with the increase of coupling efficiency.

  2. Atmospheric compensation of thermal infrared hyperspectral imagery with the emissive empirical line method and the in-scene atmospheric compensation algorithms: a comparison

    NASA Astrophysics Data System (ADS)

    DiStasio, Robert J., Jr.; Resmini, Ronald G.

    2010-04-01

    The in-scene atmospheric compensation (ISAC) algorithm of Young et al. (2002) [14] (and as implemented in the ENVI® software system [16] as 'Thermal Atm Correction') is commonly applied to thermal infrared multi- and hyperspectral imagery (MSI and HSI, respectively). ISAC estimates atmospheric transmissivity and upwelling radiance using only the scene data. The ISAC-derived transmissivity and upwelling radiance are compared to those derived from the emissive empirical line method (EELM), another in-scene atmospheric compensation algorithm for thermal infrared MSI and HSI data. EELM is based on the presence of calibration targets (e.g., panels, water pools) captured in the spectral image data for which the emissivity and temperature are well known at the moment of MSI/HSI data acquisition. EELM is similar in concept to the empirical line method (ELM) algorithm commonly applied to visible/near-infrared to shortwave infrared (VNIR/SWIR) spectral imagery and is implemented as a custom ENVI® plugin application. Both ISAC and EELM are in-scene methods and do not require radiative transfer modeling. ISAC and EELM have been applied to airborne longwave infrared (LWIR; ~7.5 ?m to ~13.5 ?m) HSI data. Captured in the imagery are calibration panels and/or water pools maintained at different temperatures facilitating the application of EELM. Overall, the atmospheric compensation parameters derived from the two methods are in close agreement: the EELM-derived ground-leaving radiance spectra generally contain fewer residual atmospheric spectral features, although ISAC sometimes produces smoother ground-leaving radiance spectra. Nonetheless, the agreement is viewed as validation of ISAC. ISAC is an effective atmospheric compensation algorithm that is readily available to the remote sensing community in the ENVI® software system. Thus studies such as the present testing and comparing ISAC to other methods are important. The ISAC and EELM algorithms are discussed as are the airborne LWIR and simulated HSI data to which they are applied. Also presented are analyses and comparisons of the retrieved transmissivity and upwelling radiance terms.

  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. Exploiting MODTRAN radiation transport for atmospheric correction: The FLAASH algorithm

    Microsoft Academic Search

    A. Berk; S. M. Adler-Golden; A. J. Ratkowski; G. W. Feldeb; G. P. Andersonb; M. L. Hoke; T. Cooley; J. H. Chetwynd; J. A. Gardner; M. W. Matthew; L. S. Bernstein; P. K. Acharya; D. Miller; P. Lewis

    2002-01-01

    Terrain categorization and target detection algorithms applied to hyperspectral imagery (HSI) typically operate on the measured reflectance (of sun and sky illumination) by an object or scene. Since the reflectance is a non-dimensional ratio, the reflectance by an object is nominally not affected by variations in lighting conditions. Atmospheric correction (referred to as atmospheric compensation, characterization, etc.) algorithms (ACAs) are

  5. Generic algorithms for motion compensation and transformation

    NASA Astrophysics Data System (ADS)

    Richter, Henryk; Stabernack, Benno; Müller, 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 4×4 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 2×2 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 8×8 DCT transformation was replaced by a simplified 4×4 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.

  6. A computerized compensator design algorithm with launch vehicle applications

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    This short paper presents a computerized algorithm for the design of compensators for large launch vehicles. The algorithm is applicable to the design of compensators for linear, time-invariant, control systems with a plant possessing a single control input and multioutputs. The achievement of frequency response specifications is cast into a strict constraint mathematical programming format. An improved solution algorithm for solving this type of problem is given, along with the mathematical necessities for application to systems of the above type. A computer program, compensator improvement program (CIP), has been developed and applied to a pragmatic space-industry-related example.

  7. A MOTION COMPENSATION ALGORITHM BASED ON NON LINEAR GEOMETRIC TRANSFORMATIONS

    E-print Network

    Cavallaro, Andrea

    that the proposed coding method improves the predicted images quality and reduces the blocking artifacts can be reduced using a motion compensated prediction of the current frame from the previous reconA MOTION COMPENSATION ALGORITHM BASED ON NON LINEAR GEOMETRIC TRANSFORMATIONS AND QUADTREE

  8. KALMAN FILTER WITH PHASE SPECTRUM COMPENSATION ALGORITHM FOR SPEECH ENHANCEMENT

    E-print Network

    KALMAN FILTER WITH PHASE SPECTRUM COMPENSATION ALGORITHM FOR SPEECH ENHANCEMENT Stephen So, Kamil K with a recent speech enhancement technique, called the phase spectrum compen- sation procedure, or PSC. More-- Kalman filter, phase spectrum compensation (PSC), speech enhancement 1. INTRODUCTION The Kalman filter

  9. Atmospheric-turbulence compensation by resonant optical backscattering from the sodium layer in the upper atmosphere

    Microsoft Academic Search

    W. Happer; G. J. MacDonald; C. E. Max; F. J. Dyson

    1994-01-01

    A new concept is described for creating artificial beacons for atmospheric-turbulence compensation. A laser tuned to the sodium [ital D][sub 2] line is used to excite resonant optical backscattering from the sodium layer in the upper atmosphere. The performance of such a system is compared with that expected from artificial beacons based on Rayleigh scattering in the lower atmosphere. It

  10. 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.

  11. Reliable phase unwrapping algorithm based on rotational and direct compensators.

    PubMed

    Heshmat, Samia; Tomioka, Satoshi; Nishiyama, Shusuke

    2011-11-20

    Phase unwrapping still plays an important role in many data-processing chains based on phase information. Here, we introduce a new phase unwrapping approach for noisy wrapped phase maps of continuous objects to improve the accuracy and computational time requirements of phase unwrapping using a rotational compensator (RC) method. The proposed algorithm is based on compensating the singularity of discontinuity sources. It uses direct compensation for adjoining singular point (SP) pairs and uses RC for other SP pairs. The performance of the proposed method is tested through both simulated and real wrapped phase data. The proposed algorithm is faster than the original algorithm with the RC and has proved efficiency compared to other phase unwrapping methods. PMID:22108880

  12. Broadband optical mammography: Breast tissue thickness compensation algorithm

    NASA Astrophysics Data System (ADS)

    Anderson, Pamela G.; Sassaroli, Angelo; Kainerstorfer, Jana M.; Krishnamurthy, Nishanth; Fantini, Sergio

    2015-03-01

    We present a method to compensate for breast tissue thickness variability in broadband, continuous-wave, parallel plate optical mammography. Tissue thickness information is relevant for the recovery of chromophore concentrations within the breast using continuous-wave, diffusion-based models that assume the breast to be in slab geometry. This method compensates for the discrepancy between the actual phantom or breast shape and the models assumed slab geometry by approximating the thickness of the probed tissue volume. In this work, we applied our tissue thickness compensation algorithm on a breast shaped, homogeneous, tissue-mimicking phantom. Using the thickness found from our algorithm (referred to as our "estimated thickness") as an input into a continuous-wave, diffusion based model, we recovered the absorption coefficient throughout all scanned pixels in the phantom and found an overall deviation of 12% from the true absorption coefficient. By using the known phantom thickness, we found a strong shape bias within the absorption coefficient recovery and a larger overall deviation of 29%. To test the algorithm on in vivo measurements, we applied this tissue thickness compensation method to a human breast cancer optical mammogram scan. Since the exact thickness of the breast at each pixel is unknown, we compared these results to when a uniform breast thickness is assumed and found a drastic improvement of cancer visualization. This method allows for parallel plate, continuous-wave optical imaging to compensate for the tissue thickness variability at each scanned pixel when modeling the breast data in slab geometry. This compensated thickness is needed as an input to the model in order to accurately map the breast chromophore concentrations and enhance the image contrast of cancer.

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

    E-print Network

    Drijfhout, Sybren

    Bjerknes Compensation at High Northern Latitudes: The Ocean Forcing the Atmosphere E. VAN DER for Bjerknes compensation of heat transport variations through the atmosphere and ocean on decadal time scales are investigated, using data output from a preindustrial control run of the Third Hadley Centre Coupled Ocean­Atmosphere

  14. Sensor Drift Compensation Algorithm based on PDF Distance Minimization

    NASA Astrophysics Data System (ADS)

    Kim, Namyong; Byun, Hyung-Gi; Persaud, Krishna C.; Huh, Jeung-Soo

    2009-05-01

    In this paper, a new unsupervised classification algorithm is introduced for the compensation of sensor drift effects of the odor sensing system using a conducting polymer sensor array. The proposed method continues updating adaptive Radial Basis Function Network (RBFN) weights in the testing phase based on minimizing Euclidian Distance between two Probability Density Functions (PDFs) of a set of training phase output data and another set of testing phase output data. The output in the testing phase using the fixed weights of the RBFN are significantly dispersed and shifted from each target value due mostly to sensor drift effect. In the experimental results, the output data by the proposed methods are observed to be concentrated closer again to their own target values significantly. This indicates that the proposed method can be effectively applied to improved odor sensing system equipped with the capability of sensor drift effect compensation

  15. 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.

  16. Combinational-deformable-mirror adaptive optics system for atmospheric compensation in free space communication

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    As we know that deformable-mirror (DM) is used in the adaptive optics (AO) systems to compensate atmospheric turbulence in free space optical (FSO) communication system. In order to get rid of the limitations generated by the characters of DM itself, the combinational-deformable-mirror (CDM) adaptive optics (CDM-AO) system is established to correct wave-front aberrations and improve coupling efficiency at the receiver. The analysis of the principle of CDM and the decoupling-working principle based on confinement correction algorithm (CCA) is provided, and the comparison of the correcting results between CDM-AO system and conventional AO system are given. Simulation results indicate that CDM-AO system can correct different aberrations with different characteristics and provide better correction performance than single deformable-mirror (DM) AO system. And the coupling efficiency improvement provided by the correction of AO system is numerically evaluated.

  17. Compensating Atmospheric Turbulence Effects at High Zenith Angles with Adaptive Optics Using Advanced Phase Reconstructors

    Microsoft Academic Search

    M. Roggemann; G. Soehnel; G. Archer

    2007-01-01

    Atmospheric turbulence degrades the resolution of images of space objects far beyond that predicted by diffraction alone. Adaptive optics telescopes have been widely used for compensating these effects, but as users seek to extend the envelopes of operation of adaptive optics telescopes to more demanding conditions, such as daylight operation, and operation at low elevation angles, the level of compensation

  18. Compensating atmospheric turbulence efiects at high zenith angles with adaptive optics using advanced phase reconstructors

    Microsoft Academic Search

    Grant Soehnel; Michael C. Roggemann; Glen Archer

    Atmospheric turbulence degrades the resolution of images of space objects beyond that predicted by difiraction alone. Adaptive optics telescopes have been widely used for compensating these efiects, but as users seek to extend the envelopes of operation of adaptive optics telescopes to more demanding conditions, such as daylight operation and operation at low elevation angles, the level of compensation pro-

  19. 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

  20. The affection analysis and compensation for atmospheric overfall in free space optical communication system

    NASA Astrophysics Data System (ADS)

    Yuan, Xiuhua; Wang, Jin; Huang, Dexiu; Liu, Deming

    2004-12-01

    The Free Space optical communication (FSO) or wireless optical communication, utilizes the atmospheric medium as transmission channel, where random variety such as fog, atomy and atmosphere flash and the atmospheric turbulence will badly affect the propagation of light, the receiving signal is easily swung and drifted with the change of weather. In this paper, we discussed the attenuation of the atmospheric channel and analyzed the signal characteristics in the condition of the atmospheric overfall, for the OOK modulation, discussed the receiving signal distribution in the atmospheric channel taking account for the noise gain of the light detector, and based on the principle of the Hartman-Shack sensor, we designed a wave-front distortion compensation system with fiber coupler. The signal fading resulted from wave-front phase distortion was compensated effectively by using the compensation system.

  1. Research on the working characteristic of Hall current sensor and the "modeling-deviation compensation" algorithm

    NASA Astrophysics Data System (ADS)

    Mu, Lili; Chen, Zekuan; Li, Zhijing

    2013-10-01

    The working characteristic of the Hall current sensor CSM025A was studied in the paper. The "modeling-deviation compensation" algorithm of adopting to compensate the deviation by the software way was proposed according to the deviation problem between actual working characteristic and ideal working characteristic of the output signal in current measurement. Experiments showed that the measurement result was accurate and the "modeling-deviation compensation" algorithm effect was good.

  2. 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.

  3. AN ATMOSPHERIC CORRECTION ALGORITHM FOR

    E-print Network

    Salvaggio, Carl

    transfer model MODTRAN 4.0. Atmospheric visibility can be derived via the NLLSSF technique from the 400 for the MODTRAN 4.0 LUT generator, with whom I have worked with these last five years on different contracts constant questioning on MODTRAN and grills a really mean smoked pork. Thank you to Tim Gallagher and Bryce

  4. Contact Friction Compensation for Robots Using Genetic Learning Algorithms

    Microsoft Academic Search

    Der-cherng Liaw; Jeng-Tze Huang

    1998-01-01

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

  5. A Synergistic Approach to Atmospheric Compensation of Neon's Airborne Hyperspectral Imagery Utilizing an Airborne Solar Spectral Irradiance Radiometer

    NASA Astrophysics Data System (ADS)

    Wright, L.; Karpowicz, B. M.; Kindel, B. C.; Schmidt, S.; Leisso, N.; Kampe, T. U.; Pilewskie, P.

    2014-12-01

    A wide variety of critical information regarding bioclimate, biodiversity, and biogeochemistry is embedded in airborne hyperspectral imagery. Most, if not all of the primary signal relies upon first deriving the surface reflectance of land cover and vegetation from measured hyperspectral radiance. This places stringent requirements on terrain, and atmospheric compensation algorithms to accurately derive surface reflectance properties. An observatory designed to measure bioclimate, biodiversity, and biogeochemistry variables from surface reflectance must take great care in developing an approach which chooses algorithms with the highest accuracy, along with providing those algorithms with data necessary to describe the physical mechanisms that affect the measured at sensor radiance. The Airborne Observation Platform (AOP) part of the National Ecological Observatory Network (NEON) is developing such an approach. NEON is a continental-scale ecological observation platform designed to collect and disseminate data to enable the understanding and forecasting of the impacts of climate change, land use change, and invasive species on ecology. The instrumentation package used by the AOP includes a visible and shortwave infrared hyperspectral imager, waveform LiDAR, and high resolution (RGB) digital camera. In addition to airborne measurements, ground-based CIMEL sun photometers will be used to help characterize atmospheric aerosol loading, and ground validation measurements with field spectrometers will be made at select NEON sites. While the core instrumentation package provides critical information to derive surface reflectance of land surfaces and vegetation, the addition of a Solar Spectral Irradiance Radiometer (SSIR) is being investigated as an additional source of data to help identify and characterize atmospheric aerosol, and cloud contributions contributions to the radiance measured by the hyperspectral imager. The addition of the SSIR provides the opportunity to conduct synergistic research which helps to improve ecological data products, while simultaneously measuring radiative properties key to understanding climate. We will present measurements from flights conducted with an SSIR, and explore methods to improve atmospheric compensation of the hyperspectral imagery.

  6. Atmospheric Correction Algorithm for Hyperspectral Imagery

    SciTech Connect

    R. J. Pollina

    1999-09-01

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

  7. The oxygen and carbon dioxide compensation points of Câ plants: Possible role in regulating atmospheric oxygen

    Microsoft Academic Search

    N. E. Tolbert; C. Benker; E. Beck

    1995-01-01

    The Oâ and COâ compensation points (Oâ and COâ) of plants in a closed system depend on the ratio of COâ and Oâ concentrations in air and in the chloroplast and the specificities of ribulose bisphosphate carboxylase\\/oxygenase (Rubisco). The photosynthetic Oâ is defined as the atmospheric Oâ level, with a given COâ level and temperature, at which net Oâ exchange

  8. New clustering algorithm-based fault diagnosis using compensation distance evaluation technique

    Microsoft Academic Search

    Yaguo Lei; Zhengjia He; Yanyang Zi; Xuefeng Chen

    2008-01-01

    This paper presents a fault diagnosis method of rotating machinery based on a new clustering algorithm using a compensation distance evaluation technique (CDET). A two-stage feature selection and weighting technique is adopted in this algorithm. Feature weights are computed via CDET according to the sensitivity of features and assigned to the corresponding features to indicate their different importance in clustering.

  9. Atmospheric compensation for WorldView-2 satellite and in-water component retrieval

    NASA Astrophysics Data System (ADS)

    Concha, Javier A.; Gerace, Aaron D.

    2012-06-01

    In the present work, the WorldView-2 (WV2) capability for retrieving Case 2 water components is analyzed. The WV2 sensor characteristics, such as a 11-bit quantization, 8 bands in the VNIR (visible and near infrared) region and high Signal-to-Noise Ratios (SNR) make WV2 potentially suitable for a retrieval process. In the Case 2 water problem, the sensor-reaching signal due to water is very small when compared to the signal due to the atmospheric eects. Therefore, adequate atmospheric compensation becomes an important rst step to accurately retrieve water parameters. The problem becomes more dicult when using multispectral imagery as there are typically only a handful of bands suitable for performing atmospheric compensation. In this work, we test atmospheric compensation techniques for the WV2 satellite, enabling it to be used for water constituent retrieval in both deep and shallow water. A look-up-table (LUT) methodology is implemented to retrieve the water parameters chlorophyll, suspended materials, colored dissolved organic matter, bathymetry, bottom type and water clarity for a simulated case study. The in-water radiative transfer code HydroLight is used to simulate re ectance data in this study while the MODTRAN code is used to simulate atmospheric eects. The resulting modeled sensor-reaching radiance data can be sampled to a WV2 sensor model to simulate WV2 image data. This data is used to test the proposed methodology. Finally, a sensitivity analysis is performed to evaluate how sensitive the constituent retrieval process is to adequate atmospheric compensation.

  10. 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

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

    PubMed Central

    2014-01-01

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

  12. Effects of different beacon wavelengths on atmospheric compensation in strong scintillation.

    PubMed

    Fan, Chengyu; Wang, Yingjian; Gong, Zhiben

    2004-08-01

    During strong scintillation, the number and location of branch points in a distorted optical field induced by atmospheric turbulence are closely related to the characteristic parameters of the turbulence effect, propagation distance, and wavelength. It is necessary to consider the effect of the beacon's wavelength on the adaptive optics system that is used to compensate for atmospheric turbulence. Our analytical results show that the performance of adaptive optics can be improved by nearly a factor of 2 when the beacon's wavelength is chosen slightly longer than the wavelength of the main laser in the branch points considered. PMID:15298405

  13. 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

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

    E-print Network

    A Resistance Compensation Control Algorithm for a Cable-Driven Hand Exoskeleton for Motor Function, hand exoskeleton 1 Introduction As we know, the motor capability of hand is crucial and important existing exoskeleton-type hand rehabilitation devices, the cable and sheath is utilized in mechanical

  15. 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.

  16. 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.

  17. Water vapor retrieval using the FLAASH atmospheric correction algorithm

    Microsoft Academic Search

    Gerald W. Felde; Gail P. Anderson; James A. Gardner; Steven M. Adler-Golden; Michael W. Matthew; Alexander Berk

    2004-01-01

    FLAASH (Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes) is a first-principles atmospheric correction algorithm for visible to shortwave infrared (SWIR) hyperspectral data. The algorithm consists of two main steps. The first is retrieval of atmospheric parameters, visibility (which is related to the aerosol type and distribution) and column water vapor. The second step is solving the radiation transport equation for

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  19. Multilevel Algorithm for Atmospheric Data Assimilation

    NASA Technical Reports Server (NTRS)

    Brandt, Achi; Zaslavsky, Leonid Yu.

    1996-01-01

    A multiscale algorithm for the problem of optimal statistical interpolation of observed data has been developed. This problem includes the calculation of the vector of the 'analyzed' (best estimated) atmosphere flow field w(sup a) by the formula: w(sup a) = w(sup f) + P(sup f) H(sup T) y, where the quantity y is defined by the equation (H P(sup f) H(sup T) + R)y = w(sup o) - H w(sup f), using the given model forecast first guess w(sup f) and the vector of observations w(sup o); H is an interpolation operator from the regular grid to the observation network, P(sup f) is the forecast error covariance matrix, and R is the observation error covariance matrix. At this initial stage the case of univariate analysis of single level radiosonde height data is considered. The matrix R is assumed to be diagonal, and the matrix P(sup f) is assumed to be given by the formula P(sub ij)(sup f) = sigma(sub i)(sup f) mu(sub ij) sigma(sub j)(sub f), where mu(sub ij) is a smooth, decreasing function of the distance between the i-th and the j-th points. In this paper we describe a multiscale iterative process based on a multiresolution, simultaneous displacement technique and a localized variational calculation of iteration parameters.

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

    Microsoft Academic Search

    Veligdan; James T

    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

  1. 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.

  2. 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 advection–diffusion 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

  3. Acceleration of motion-compensated PET reconstruction: ordered subsets-gates EM algorithms and a priori reference gate information

    Microsoft Academic Search

    N. Dikaios; T. D. Fryer

    2011-01-01

    Patient motion during positron emission tomography scans leads to significant resolution loss and image degradation. Motion-compensated image reconstruction (MCIR) algorithms have proven to be reliable correction methods given accurate deformation fields. However, although ordered subsets (OS) are widely used to speed up the convergence, OS-MCIR algorithms are still computationally expensive. This study concentrates on acceleration of OS-MCIR algorithms through two

  4. Algorithm for atmospheric corrections of aircraft and satellite imagery

    Microsoft Academic Search

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

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  6. MTRC compensation in high-resolution ISAR imaging via improved polar format algorithm based on ICPF

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Xu, Shiyou; Chen, Zengping; Yuan, Bin

    2014-12-01

    In this paper, we present a detailed analysis on the performance degradation of inverse synthetic aperture radar (ISAR) imagery with the polar format algorithm (PFA) due to the inaccurate rotation center. And a novel algorithm is developed to estimate the rotation center for ISAR targets to overcome the degradation. In real ISAR scenarios, the real rotation center shift is usually not coincided with the gravity center of the high-resolution range profile (HRRP), due to the data-driven translational motion compensation. Because of the imprecise information of rotation center, PFA image yields model errors and severe blurring in the cross-range direction. To tackle this problem, an improved PFA based on integrated cubic phase function (ICPF) is proposed. In the method, the rotation center in the slant range is estimated firstly by ICPF, and the signal is shifted accordingly. Finally, the standard PFA algorithm can be carried out straightforwardly. With the proposed method, wide-angle ISAR imagery of non-cooperative targets can be achieved by PFA with improved focus quality. Simulation and real-data experiments confirm the effectiveness of the proposal.

  7. Depth compensation in fluorescence molecular tomography using an adaptive support driven reweighted L1-minimization algorithm

    NASA Astrophysics Data System (ADS)

    Shi, Junwei; Liu, Fei; Luo, Jianwen; Bai, Jing

    2014-09-01

    In fluorescence molecular tomography (FMT), the fluorophore distribution is reconstructed using the diffuse-light measurements obtained from the rotating source-detector pairs placed on the boundary of the tissues. Owing to the intensity attenuation of light when it propagates through tissues, the sensitivity of measurements deteriorates quickly with increased depth. Thus the inconsistent contrast of reconstructed fluorophores located at different depths is a major challenge in FMT. As a spatially variant regularization method, the adaptive support driven reweighted L1-minimization (ASDR-L1) algorithm is proposed here for depth compensation in FMT. ASDR-L1 is a modification of the restarted L1 regularization-based nonlinear conjugate gradient (re-L1-NCG) algorithm previously proposed by our laboratory. In ASDR-L1, the original L1-minimization problem is replaced by a sequence of weighted L1-minimization subproblems with spatially updated weights applied to the adaptive support estimate. Like re-L1-NCG, ASRDR-L1 adopts the restarted strategy in each outer iteration, which contributes to the adaptive support estimate. The updated weights for the next iteration spatially depend on the current solution. In the support estimate, spatially updated weights mean different regularization parameters for different locations. A large regularization parameter in the weighted L1-minimization subproblem makes the results concentrate on a small number of large values, whereas a small regularization parameter tends to make the values be evenly distributed. Thus depth compensation in FMT is achieved through the iteratively updated weights. Simulation experiments are conducted to confirm the feasibility of ASDR-L1. Through ASDR-L1, the reconstructed contrast between two identical fluorophores located at different depths is increased from 1:0.43 to 1:0.96.

  8. Accuracies of three computationally efficient algorithms for computing atmospheric transmittances

    NASA Technical Reports Server (NTRS)

    Mcmillin, L. M.; Fleming, H. E.; Arking, A.; Chesters, D.

    1980-01-01

    Three algorithms for calculating polychromatic atmospheric transmittance functions have been tested using a set of eleven distinct temperature profiles in order to compare transmittance accuracies achievable by the three methods. The comparison of rms errors demonstrates that the iterative method of McMillin and Fleming (1976) is the most accurate of the efficient algorithms currently available for gases with constant mixing ratios; its accuracy approaches that of the spectroscopic parameters and the computational approximations used in the ground-truth line-by-line calculations. The method of Arking et al. (1974), while less accurate, has the advantage of being perfectly general and easily adapted to cases where spectral bandwidths are varied

  9. 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 4?m PV value for test, which is mixed with two 70?m wave length sine-waves, the max profile error at the angle of fifteen is less than 0.01?m turning by a diamond tool with big radius of 80?m. The sinusoidal grid is machined on a ultra-precision lathe succesfully, the wavelength is 70.2278?m the Ra value is 22.81nm evaluated by data points generated by filtering out the first five harmonics.

  10. 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.

  11. Low-complexity logarithmic step-size-based filtered digital backward propagation algorithm for compensating fiber transmission impairments

    NASA Astrophysics Data System (ADS)

    Asif, Rameez; Lin, Chien-Yu; Holtmannspoetter, Michael; Schmauss, Bernhard

    2012-01-01

    We have investigated a new method to reduce the complexity of the digital backward propagation algorithm (DBP). A logarithmic step-size based split-step Fourier method (SSFM) is investigated in this paper to compensate fiber transmission impairments i.e. chromatic dispersion (CD) and non-linearities (NL) in dual-polarization quadrature phase shift keying (DP-QPSK) system. The algorithm is numerically investigated for coherently-detected multiple channel DP-QPSK system over 2000km (25 spans) standard single mode fiber (SMF-28) with un-compensated transmission link. The algorithm is numerically evaluated for: (a) 20 channel 56Gbit/s (14GBaud) with 25GHz channel spacing; (b) 10 channel 112Gbit/s (28GBaud) with 50GHz channel spacing and (c) 5 channel 224Gbit/s (56GBaud) with 100GHz channel spacing. Each simulation configuration has the bandwidth occupancy of 500GHz and a total transmission capacity of 1.12Tbit/s. The logarithmic DBP algorithm (L-DBP) shows efficient results as compared to the conventional DBP method based on modified SSFM (M-DBP). The results depict efficient mitigation of CD and NL, therefore improving the non-linear threshold point (NLT) upto 4dB. Furthermore by implementing a low-pass-filter (LPF) in each SSFM step, the required number of DBP stages to compensate fiber transmission impairments can be significantly reduced (multi-span DBP) by 75% as compared to L-DBP and by 50% as compared to M-DBP. The results delineate improved system performance of logarithmic step size based filtered DBP (FL-DBP) both in terms of efficiency and complexity which will be helpful in future deployment of DBP algorithm with real-time signal processing modules for non-linear compensation.

  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. 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.

  14. Validation of the QUick atmospheric correction (QUAC) algorithm for VNIR-SWIR multi- and hyperspectral imagery

    Microsoft Academic Search

    Lawrence S. Bernstein; Steven M. Adler-Golden; Robert L. Sundberg; Robert Y. Levine; Timothy C. Perkins; Alexander Berk; Anthony J. Ratkowski; Gerald Felde; Michael L. Hoke

    2005-01-01

    We describe a new visible-near infrared short-wavelength infrared (VNIR-SWIR) atmospheric correction method for multi- and hyperspectral imagery, dubbed QUAC (QUick Atmospheric Correction) that also enables retrieval of the wavelength-dependent optical depth of the aerosol or haze and molecular absorbers. It determines the atmospheric compensation parameters directly from the information contained within the scene using the observed pixel spectra. The approach

  15. 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.

  16. Acceleration of motion-compensated PET reconstruction: ordered subsets-gates EM algorithms and a priori reference gate information.

    PubMed

    Dikaios, N; Fryer, T D

    2011-03-21

    Patient motion during positron emission tomography scans leads to significant resolution loss and image degradation. Motion-compensated image reconstruction (MCIR) algorithms have proven to be reliable correction methods given accurate deformation fields. However, although ordered subsets (OS) are widely used to speed up the convergence, OS-MCIR algorithms are still computationally expensive. This study concentrates on acceleration of OS-MCIR algorithms through two methods: combining OS with motion subsets and use of an initial estimate based on reference gate data. These approaches were compared to two existing OS-MCIR algorithms and post-reconstruction registration using data from the NCAT phantom. The methods were evaluated in terms of noise, lesion bias and contrast-to-noise ratio (CNR). The straightforward combination of motion subsets with projection subsets (OSGEM) produced inferior results (lower CNR, p < 0.01) to existing OS-MCIR algorithms. The addition of a spacer step using data from all gates to OSGEM resulted in an algorithm (SS-OSGEM) that generated images that were statistically consistent with those from existing OS-MCIR algorithms (no significant difference in CNR, p > 0.05) at one third of the computational expense. The use of a reference gate initial estimate (MCDOi) resulted in comparable image quality in terms of bias and CNR (p > 0.05) at half the computational burden. This study indicates that MCDOi and SS-OSGEM in particular are attractive accelerated OS-MCIR approaches. PMID:21346272

  17. 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.

  18. 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

  19. 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

  20. 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

  1. An Algorithm for ODES from Atmospheric Dispersion I. Ahmad and M. Berzins

    E-print Network

    Utah, University of

    the source. The transport of the plume and the chemical reactions are modelled by the atmospheric diffusionAn Algorithm for ODES from Atmospheric Dispersion Problems. I. Ahmad and M. Berzins School of ordinary differential equations o.d.e.s, arising from atmospheric dispersion problems is considered

  2. Global Soundings of the Atmosphere from ATOVS Measurements: The Algorithm and Validation

    Microsoft Academic Search

    Jun Li; Walter W. Wolf; W. Paul Menzel; Wenjian Zhang; Hung-Lung Huang; Thomas H. Achtor

    2000-01-01

    The International Advanced Television and Infrared Observation Satellite Operational Vertical Sounder (ATOVS) Processing Package (IAPP) has been developed to retrieve the atmospheric temperature profile, moisture profile, atmospheric total ozone, and other parameters in both clear and cloudy atmospheres from the ATOVS measurements. The algorithm that retrieves these parameters contains four steps: 1) cloud detection and removal, 2) bias adjustment for

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

    Microsoft Academic Search

    Lang Wang; Shuxu Guo; Lingjia Gu; Ruizhi Ren

    2008-01-01

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

  4. 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

  5. One End Simplified Fault Location Algorithm Using Instantaneous Values for series compensated High Voltage Transmission lines

    Microsoft Academic Search

    S. K. Kapuduwage; M. Al-Dabbagh

    Reactive power compensation, using series capacitors unit (SCU) in high voltage power transmission is widely used to improve the efficiency of the power transfer between transmission networks. However, such applications affect the design and application of devices such as fault locaters and protection schemes in transmission networks. This seems to be one of the most difficult tasks for manufactures, operators

  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 oxygen and carbon dioxide compensation points of C3 plants: possible role in regulating atmospheric oxygen.

    PubMed

    Tolbert, N E; Benker, C; Beck, E

    1995-11-21

    The O2 and CO2 compensation points (O2 and CO2) of plants in a closed system depend on the ratio of CO2 and O2 concentrations in air and in the chloroplast and the specificities of ribulose bisphosphate carboxylase/oxygenase (Rubisco). The photosynthetic O2 is defined as the atmospheric O2 level, with a given CO2 level and temperature, at which net O2 exchange is zero. In experiments with C3 plants, the O2 with 220 ppm CO2 is 23% O2; O2 increases to 27% with 350 ppm CO2 and to 35% O2 with 700 ppm CO2. At O2 levels below the O2, CO2 uptake and reduction are accompanied by net O2 evolution. At O2 levels above the O2, net O2 uptake occurs with a reduced rate of CO2 fixation, more carbohydrates are oxidized by photorespiration to products of the C2 oxidative photosynthetic carbon cycle, and plants senesce prematurely. The CO2 increases from 50 ppm CO2 with 21% O2 to 220 ppm with 100% O2. At a low CO2/high O2 ratio that inhibits the carboxylase activity of Rubisco, much malate accumulates, which suggests that the oxygen-insensitive phosphoenolpyruvate carboxylase becomes a significant component of the lower CO2 fixation rate. Because of low global levels of CO2 and a Rubisco specificity that favors the carboxylase activity, relatively rapid changes in the atmospheric CO2 level should control the permissive O2 that could lead to slow changes in the immense O2 pool. PMID:11607591

  8. 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.

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

    SciTech Connect

    Frolov, Vladimir [Moscow Inst. of Physics and Technology (MIPT), Moscow (Russian Federation); Backhaus, Scott N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    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

  10. An Automatic Spring-back Compensation Die Design Method Based on Genetic Algorithm and Isotropic-Kinematic Hardening Laws

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Xing; Hu, Jing; Chung, Kwansoo; Zhou, Guo-Feng; Yao, Rao

    2011-08-01

    We present the study of a finite element method for die contour to compensate spring-back in sheet metal forming process, which is based on the genetic algorithm and isotropic-kinematic hardening laws. The Chaboche type combined isotropic-kinematic hardening law was formulated and used to account for the Bauschinger and transient behavior in the finite element analysis. Using a S shape stretch bending process as an example, it was demonstrated that the new method optimizes the die profile effectively. The good performance of the die profile optimized utilizing the new method was also experimentally verified , confirming that the new method might be more effective in cost reduction than common design practices in practical applications.

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

    E-print Network

    Betremieux, Yan

    2015-01-01

    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 HD189733b, 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 atmosphere, but that it is important to ...

  12. A VNIR\\/SWIR atmospheric correction algorithm for hyperspectral imagery with adjacency effect

    Microsoft Academic Search

    Lee C. Sanders; John R. Schott; Rolando Raqueño

    2001-01-01

    Radiometrically calibrated hyperspectral imagery contains information relating to the material properties of a surface target and the atmospheric layers between the surface target and the sensor. All atmospheric layers contain well-mixed molecular gases, aerosol particles, and water vapor, and information about these constituents may be extracted from hyperspectral imagery by using specially designed algorithms. This research describes a total sensor

  13. 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

  14. Evaluation of MODIS SWIR and NIR-SWIR atmospheric correction algorithms using SeaBASS data

    Microsoft Academic Search

    Menghua Wang; SeungHyun Son; Wei Shi

    2009-01-01

    Using the NASA maintained ocean optical and biological in situ data that were collected during 2002–2005, we have evaluated the performance of atmospheric correction algorithms for the ocean color products from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua. Specifically, algorithms using the MODIS shortwave infrared (SWIR) bands and an approach using the near-infrared (NIR) and SWIR combined method are

  15. Semi-Empirical, Multi-Wavelength Raman Gain Engineering Algorithm with Pump Interaction Compensation Technique

    E-print Network

    Park, Namkyoo

    algorithm for the precise engineering of multi-channel gain profile of Raman amplifier. By employing optical transmission systems. Of various advantages that the Raman amplifier provides for, the flexible allocation, and expansion capability of the gain band distinguishes Raman amplifier from any other types

  16. 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.

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

    SciTech Connect

    Frolov, Vladimir [Moscow Inst. of Physics and Technology (MIPT), Moscow (Russian Federation); Backhaus, Scott N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    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.

  18. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  20. The oxygen and carbon dioxide compensation points of C{sub 3} plants: Possible role in regulating atmospheric oxygen

    SciTech Connect

    Tolbert, N.E. [Michigan State Univ., East Lansing, MI (United States); Benker, C.; Beck, E. [Universitaet Bayreuth (Germany)

    1995-11-21

    The O{sub 2} and CO{sub 2} compensation points (O{sub 2} and CO{sub 2}) of plants in a closed system depend on the ratio of CO{sub 2} and O{sub 2} concentrations in air and in the chloroplast and the specificities of ribulose bisphosphate carboxylase/oxygenase (Rubisco). The photosynthetic O{sub 2} is defined as the atmospheric O{sub 2} level, with a given CO{sub 2} level and temperature, at which net O{sub 2} exchange is zero. In experiments with C{sub 3} plants, the O{sub 2} with 220 ppm CO{sub 2} is 23% O{sub 2}; O{sub 2} increases to 27% with 350 ppm CO{sub 2} and to 35% O{sub 2} with 700 ppm CO{sub 2}. At O{sub 2} levels below the O{sub 2}, CO{sub 2} uptake and reduction are accompanied by net O{sub 2} levels below the O{sub 2}, CO{sub 2} uptake and reduction are accompanies by net O{sub 2} evolution. At O{sub 2} levels above the O{sub 2}, net O{sub 2} uptake occurs with a reduced rate of CO{sub 2} fixation, more carbohydrates are oxidized by photorepiration to products of the C{sub 2} oxidative photosynthetic carbon cycle, and plants senesce prematurely. The CO{sub 2} increases from 50 ppm CO{sub 2} with 21% O{sub 2} to 220 ppm with 100% O{sub 2}. At a low CO{sub 2}/high O{sub 2} ratio that inhibits the carboxylase activity of Rubisco, much malate accumulates, which suggests that the oxygen-insensitive phosphoenolpyruvate carboxylase becomes a significant component of the lower CO{sub 2} fixation rate. Because of low component of the lower CO{sub 2} and a Rubisco specificity that favors the carboxylase activity, relatively rapid changes in the atmospheric CO{sub 2} level should control the permissive O{sub 2} that could lead to slow changes in the immense O{sub 2} pool.

  1. Algorithm of atmosphere turbulence detection with airborne weather radar

    Microsoft Academic Search

    I. G. Prockopenko; Felix J. Yanovsky

    1995-01-01

    The aim of the paper is to show the analysis of methods of turbulence detection by two informative parameters, evaluation of their reliability, and synthesis of the algorithm of signal processing, particularly for non-Gaussian distributions

  2. An Improved Atmospheric Correction Algorithm for Hyperspectral Remotely Sensed Imagery

    Microsoft Academic Search

    Shunlin Liang; Hongliang Fang

    2004-01-01

    Abstract, There is an increased trend toward quantitative estimation of land surface variables from hyperspectral remote sensing. One challenging issue is retrieving surface reflectance spectra from observed radiance through atmospheric correction, most methods for which are intended to correct water vapor and other absorbing gases. In this letter, methods for correcting both aerosols and water vapor are explored. We first

  3. 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.

  4. Validation and robustness of an atmospheric correction algorithm for hyperspectral images

    Microsoft Academic Search

    Yannick Boucher; Laurent Poutier; Veronique Achard; Xavier Lenot; Christophe Miesch

    2002-01-01

    The Optics Department of ONERA has developed and implemented an inverse algorithm, COSHISE, to correct hyperspectral images of the atmosphere effects in the visible-NIR-SWIR domain (0,4-2,5 micrometers ). This algorithm automatically determine the integrated water-vapor content for each pixel, from the radiance at sensor level by using a LIRR-type (Linear Regression Ratio) technique. It then retrieves the spectral reflectance at

  5. 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.

  6. Two-stage adaptive PMD compensation in a 10 Gbit\\/s optical communication system using particle swarm optimization algorithm

    Microsoft Academic Search

    Xiaoguang Zhang; Li Yu; Yuan Zheng; Yu Shen; Guangtao Zhou; Lin Chen; Lixia Xi; Tiecheng Yuan; Jianzhong Zhang; Bojun Yang

    2004-01-01

    An experimental investigation of polarization mode dispersion (PMD) adaptive compensation for 10 Gbit\\/s NRZ and RZ optical communication systems using a two-stage PMD compensator is reported. A monitoring technique based on degree of polarization (DOP) feedback-signals was adopted. Two filtering techniques were used to obtain best estimates of the actual DOP from measurement data. For the first time the particle

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  9. Development of atmospheric correction algorithm for Geostationary Ocean Color Imager (GOCI)

    NASA Astrophysics Data System (ADS)

    Ahn, Jae-Hyun; Park, Young-Je; Ryu, Joo-Hyung; Lee, Boram; Oh, Im Sang

    2012-09-01

    This paper describes an atmospheric correction algorithm for Geostationary Ocean Color Imager (GOCI) and its early phase evaluation. This algorithm was implemented in GOCI Data Processing System (GDPS) version 1.1. The algorithm is based on the standard SeaWiFS method, which accounts for multiple scattering effects and partially updated in terms of turbid case-2 water correction, optimized aerosol models, and solar angle correction per slot. For turbid water correction, we used a regional empirical relationship between water reflectance at the red (660 nm) and near infrared bands (745 nm and 865 nm). The relationship was derived from turbid pixels in satellite images after atmospheric correction, and processed using aerosol properties derived for neighboring non-turbid waters. For validation of the GOCI atmospheric correction, we compared our results with in situ measurements of normalized water leaving radiance ( nL w ) spectra that were obtained during several cruises in 2011 around Korean peninsula. The match up showed an acceptable result with mean ratio of the GOCI to in situ nL w ( ?), 1.17, 1.24, 1.26, 1.15, 0.86 and 0.99 at 412 nm, 443 nm, 490 nm, 555 nm, 660 nm and 680 nm, respectively. It is speculated that part of the deviation arose from a lack of vicarious calibration and uncertainties in the above water nLw measurements.

  10. 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.

  11. A novel fair queuing algorithm for hybrid wired/wireless architecture with wireless compensation to provide end-to-end quality of service support

    NASA Astrophysics Data System (ADS)

    Sana, Ajaz; Ye, Xin; Hussain, Shahab; Ali, Mohammed A.; Ahmed, Samir

    2007-09-01

    We proposed novel hybrid FSO/RF architecture1 to provide broadband wireless access to end users. To provide quality of service (QoS) bounds for different types of traffic(voice, video and data) we proposed some fair queuing algorithms 2,3 ,but because of the hybrid wired and wireless links there can be certain times allocated to a host when that host is unable to transmit data because of wireless link errors. These wireless link errors are location dependent and bursty. The channel errors can occur from multi-path fading, shadow fading or interference from another device. In this paper we proposed a novel fair queuing algorithm to provide end to end QoS bounds to the end users for the proposed architecture .The algorithm provide QoS bounds for Ethernet traffic in the wired domain as well as in wireless domain with compensation for wireless link errors. Scheduler maps priorities and weights for QoS of the Ethernet traffic into wireless MAC. By supporting existing Ethernet traffic QoS parameters 4-7, scheduler avoids the need to redefine QoS parameters for wireless channel. By simulations and analysis we proved that the algorithm guarantees (1) delay and throughput for error-free flows, (2) short term fairness among error-free flows, (3) long term fairness among errored and error-free flows,(4) graceful degradation for leading flows and graceful compensation for lagging flows. Each connection QoS is guaranteed by calculating bounds on delay and reserving the Bandwidth (BW).

  12. 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.

  13. 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.

  14. A procedure for testing the quality of LANDSAT atmospheric correction algorithms

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  15. 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.

  16. 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.

  17. 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 Université 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.

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

    SciTech Connect

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

    1987-02-20

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  20. 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.

  1. Atmosphere

    NSDL National Science Digital Library

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

    2003-01-01

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

  2. 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. [Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT (United Kingdom)

    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.

  3. Development of an alternative Martain atmospheric correction algorithm for OMEGA/Mars Express im-agery. H. Guan1

    E-print Network

    Texas at San Antonio, University of

    Development of an alternative Martain atmospheric correction algorithm for OMEGA/Mars Express im.R.China (mqzhu@ecit.edu.cn). Introduction: The OMEGA/Mars Express hyper- spectral imagery of Mars surface of the OMEGA scene (Or- bit 0501_4) (Figure 1). Figure 1. Calculated values of ln(-ln(I/F/r')) for 5 se- lected

  4. 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.

  5. 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.

  6. Compensation in pulsed alternators

    Microsoft Academic Search

    S. B. Pratap; M. D. Driga

    1999-01-01

    This paper presents a generic discussion on compensation in pulsed alternators. It covers all aspects of compensation i.e., types of compensation, alternative methods for the physical realization of the various compensation schemes, the pros and cons of compensation or the rationale for compensation. The intent of this paper is to form a guiding reference on the issues of compensation in

  7. An algorithm for retrieving water vapor profiles in clear and cloudy atmospheres from 183 GHz radiometric measurements - Simulation studies

    NASA Technical Reports Server (NTRS)

    Wilheit, Thomas T.

    1990-01-01

    The latent heat represented by atmospheric water vapor is extremely important to the energetics of the earth system. Future satellites (NOAA and DMSP) will carry microwave radiometers designed to measure the profile of water vapor globally. The problem of retrieving water vapor from the measurements is highly nonlinear even in clear atmospheres and the addition of clouds only makes it more so. In this paper, an algorithm with several novel features, which will retrieve water vapor profiles from microwave radiometric measurements even in the presence of clouds, is developed. Simulations with this algorithm show a vertical resolution on the order of 3 km and that clouds are well handled in many, but not all, circumstances. The most surprising result is that clouds can actually improve the vertical resolution of the retrieval.

  8. CEO Compensation

    E-print Network

    Frydman, Carola

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

  9. 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.

  10. Multidomain Pixel Analysis for Illuminant Estimation and Compensation

    E-print Network

    Schettini, Raimondo

    Multidomain Pixel Analysis for Illuminant Estimation and Compensation Arcangelo Brunaa , Francesca Bicocca, Italy. ABSTRACT The illuminant estimation has an important role in many domain applications compensation of the ambient illumination effects. In this paper we present an algorithm, not dependent

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

    NASA Astrophysics Data System (ADS)

    Schneider, Sébastien; 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.

  12. Improved methodology for surface and atmospheric soundings, error estimates, and quality control procedures: the atmospheric infrared sounder science team version-6 retrieval algorithm

    NASA Astrophysics Data System (ADS)

    Susskind, Joel; Blaisdell, John M.; Iredell, Lena

    2014-01-01

    The atmospheric infrared sounder (AIRS) science team version-6 AIRS/advanced microwave sounding unit (AMSU) retrieval algorithm is now operational at the Goddard Data and Information Services Center (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. Some of the significant improvements in retrieval methodology contained in the version-6 retrieval algorithm compared to that previously used in version-5 are described. 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. The improvements of some AIRS version-6 and version-6 AO products compared to those obtained using version-5 are also demonstrated.

  13. A joint effort to deliver satellite retrieved atmospheric CO2 concentrations for surface flux inversions: the ensemble median algorithm EMMA

    NASA Astrophysics Data System (ADS)

    Reuter, M.; Bösch, H.; Bovensmann, H.; Bril, A.; Buchwitz, M.; Butz, A.; Burrows, J. P.; O'Dell, C. W.; Guerlet, S.; Hasekamp, O.; Heymann, J.; Kikuchi, N.; Oshchepkov, S.; Parker, R.; Pfeifer, S.; Schneising, O.; Yokota, T.; Yoshida, Y.

    2013-02-01

    We analyze an ensemble of seven XCO2 retrieval algorithms for SCIAMACHY (scanning imaging absorption spectrometer of atmospheric chartography) and GOSAT (greenhouse gases observing satellite). The ensemble spread can be interpreted as regional uncertainty and can help to identify locations for new TCCON (total carbon column observing network) validation sites. Additionally, we introduce the ensemble median algorithm EMMA combining individual soundings of the seven algorithms into one new data set. The ensemble takes advantage of the algorithms' independent developments. We find ensemble spreads being often < 1 ppm but rising up to 2 ppm especially in the tropics and East Asia. On the basis of gridded monthly averages, we compare EMMA and all individual algorithms with TCCON and CarbonTracker model results (potential outliers, north/south gradient, seasonal (peak-to-peak) amplitude, standard deviation of the difference). Our findings show that EMMA is a promising candidate for inverse modeling studies. Compared to CarbonTracker, the satellite retrievals find consistently larger north/south gradients (by 0.3-0.9 ppm) and seasonal amplitudes (by 1.5-2.0 ppm).

  14. Compensating Mass Matrix Potential Constrained Molecular Dynamics

    E-print Network

    .Jain@jpl.nasa.gov Journal of Computational Physics, Jul, '97 (in press) Subject classification: 65P99, 82A71. KeywordsCompensating Mass Matrix Potential for Constrained Molecular Dynamics Abhinandan Jain Jet: Molecular dynamics, algorithms, simulation. #12; Running head: Compensating Potential for Constrained

  15. 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.

  16. 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.

  17. Algorithms for nonlinear retrieval problems in atmospheric remote sensing using regularization methods

    Microsoft Academic Search

    Fabian O. Gonzalez; Miguel Velez-Reyes

    1998-01-01

    In this paper, we present a retrieval algorithm for nonlinear retrieval problems based on regularization theory. The proposed method is based on the Gauss-Newton method for nonlinear least square problems. In the proposed algorithm, Tikhonov and truncated singular value decomposition techniques are used to regularize the solution of the linearization problem used to compute the Gauss-Newton search direction. The dependency

  18. 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.

  19. Retrieval of atmospheric CO2 from satellite near-infrared nadir spectra: inter-comparison of different algorithms

    NASA Astrophysics Data System (ADS)

    Reuter, M.; Buchwitz, M.; Schneising, O.; Heymann, J.; Bovensmann, H.; Burrows, J. P.

    2012-04-01

    Carbon dioxide is the most important anthropogenic greenhouse gas. Its global increasing concentration in the Earth's atmosphere is the main driver for global warming. However, in spite of its importance, there are still large uncertainties on its global sources and sinks. Satellite measurements, if accurate and precise enough, have the potential to reduce these surface flux uncertainties. At present, there are only two satellite instruments orbiting the Earth which are able to measure the CO2 mixing ratio (XCO2) with large sensitivity also in the boundary layer. These are SCIAMACHY (launched in 2002) and GOSAT (launched in 2009). Worldwide, several teams of scientists are developing algorithms aiming to meet the challenging user requirements. The majority of these groups take part in ESA's climate change initiative (CCI) on greenhouse gases (GHG) where there algorithms stand into competition. Within the presentation, recent inter-comparison results will be shown focusing on global SCIAMACHY nadir observations.

  20. Atmospheres

    NASA Astrophysics Data System (ADS)

    Bott, June; Yin, Hongbin; Sridhar, Seetharaman

    2014-12-01

    When high Al containing Fe alloys such as TRIP steels are exposed to atmospheres that contain N2 during re-heating, sub-surface nitrides form and these can be detrimental to mechanical properties. Nitride precipitation can be controlled by minimizing the access of the gaseous atmosphere to the metal surface, which can be achieved by a rapid growth of a continuous and adherent surface scale. This investigation utilizes a Au-image furnace attached to a confocal scanning microscope to simulate the annealing temperature vs time while Fe-Al alloys (with Al contents varying from 1 to 8 wt pct) are exposed to a O2-N2 atm with 10-6 atm O2. The heating times of 1, 10, and 100 minutes to the isothermal temperature of 1558 K (1285 °C) were used. It was found that fewer sub-surface nitride precipitates formed when the heating time was lowered and when Al content in the samples was increased. In the 8 wt pct samples, no internal nitride precipitates were present regardless of heating time. In the 3 and 5 wt pct samples, internal nitride precipitates were nearly more or less absent at heating times less than 10 minutes. The decrease in internal precipitates was governed by the evolving structure of the external oxide-scale. At low heating rates and/or low Al contents, significant Fe-oxide patches formed and these appeared to allow for ingress of gaseous N2. For the slow heating rates, ingress could have happened during the longer time spent in lower temperatures where non-protective alumina was present. As Al content in the alloy was increased, the external scale was Al2O3 and/or FeAl2O4 and more continuous and consequently hindered the N2 from accessing the metal surface. Increasing the Al content in the alloy had the effect of promoting the outward diffusion of Al in the alloy and thereby assisting the formation of the continuous external layer of Al2O3 and/or FeAl2O4.

  1. 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.

  2. Adaptive heave compensation via dynamic neural networks

    Microsoft Academic Search

    D. G. Lainiotis; K. N. Plataniotis; D. Menon; C. J. Charalampous

    1993-01-01

    This paper discusses the problem of adaptive heave compensation. A new estimator based on dynamic recurrent neural networks is applied to this problem. It is shown that the new algorithm is well suited for online implementation and has excellent performance. Computational results via extensive simulations are provided to illustrate the effectiveness of the algorithm. A comparative evaluation with conventional methods

  3. 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.

  4. Two-wavelength lidar inversion algorithm for a two-component atmosphere

    NASA Astrophysics Data System (ADS)

    Ackermann, Jörg

    1997-07-01

    A method for the boundary-value determination of aerosol extinction profiles from backscatter lidar measurements is presented. Artificially generated lidar signals from two-component inhomogeneous model atmospheres are inverted with the information from two wavelengths (532 and 1064 nm) simultaneously. The solution for the vertical aerosol extinction profile is formulated with Klett s far-end solution. The boundary value is expressed in terms of aerosol transmission along the lidar line according to Fernald s solution of the lidar equation. The aerosol transmission is determined iteratively with a transcendental equation on the assumption that a linear relationship exists between the extinction coefficients at both wavelengths. Inversion calculations are applied to model atmospheres with range-dependent lidar ratios representing the growth of aerosol particles caused by increasing relative humidity in the planetary boundary layer. For the inversion constant lidar ratios are assumed that vary between 40 and 70 sr. The numerical procedure turns out to be stable enough to provide meaningful results even in cases of misestimated lidar ratios. The application of the method is of less use for misestimated background radiation and low aerosol concentrations.

  5. 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.

  6. Power Factor Compensation (PFC) Power Factor Compensation

    E-print Network

    Knobloch,Jürgen

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

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

    NASA Astrophysics Data System (ADS)

    Ma, Denglong; Wang, Simin; Zhang, Zaoxiao

    2014-09-01

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

  8. Ecomp Executive Compensation Database

    NSDL National Science Digital Library

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

  9. A novel fair queuing algorithm for hybrid wired\\/wireless architecture with wireless compensation to provide end-to-end quality of service support

    Microsoft Academic Search

    Ajaz Sana; Xin Ye; Shahab Hussain; Mohammed A. Ali; Samir Ahmed

    2007-01-01

    We proposed novel hybrid FSO\\/RF architecture1 to provide broadband wireless access to end users. To provide quality of service (QoS) bounds for different types of traffic(voice, video and data) we proposed some fair queuing algorithms2,3 ,but because of the hybrid wired and wireless links there can be certain times allocated to a host when that host is unable to transmit

  10. A geometrical approach for online error compensation of industrial manipulators

    Microsoft Academic Search

    Shabbir Kurbanhusen Mustafa; Pey Yuen Tao; Guilin Yang; I-Ming Chen

    2010-01-01

    In this paper, a comprehensive online error compensation approach using offline calibration results is proposed for industrial manipulators (with closed control architecture), in order to improve its accuracy. The contents in this paper include a calibration algorithm based on the product-of-exponential formula, an online error compensation procedure for implementing the calibration results on industrial manipulators, and an experimental study that

  11. Second Order Motion Compensation for Squinted Spotlight Synthetic Aperture Radar

    E-print Network

    Second Order Motion Compensation for Squinted Spotlight Synthetic Aperture Radar Minh Phuong Nguyen motion com- pensation (MoCom) algorithm for squinted spotlight synthetic aperture radar (SAR). A preciseCom accomplishes a phase error compensation considered for every position in the spot. For pulsed SAR with a squint

  12. Iterative compensation for hysteresis effects in positioning and tracking problems

    NASA Astrophysics Data System (ADS)

    Tseng, C.; Mayergoyz, I.; McAvoy, P.; Krafft, C.

    2008-04-01

    An iterative algorithm for hysteresis compensation in micropositioning applications is presented. It is demonstrated that this algorithm has a geometric rate of convergence. The results of the testing of this iterative algorithm in tracking problems related to magnetic recording are reported.

  13. 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.

  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. Research on the PWM Waveform Compensation Algorism

    Microsoft Academic Search

    Li Nianqiang; Zhang Lu; Wei Changzhi

    2007-01-01

    In this paper, dynamic PWM waveform compensation algorithm is introduced in detail. The PWM waveform is generated with FPGA (field programmable gate array). The hardware is based on the Altera's FPGA-Cyclone-II EP2C8 and its configuration device-EPC2LC20. The software is developed under the Altera's development environment qartusII 6.0 and NIOS II CPU in FPGA. In this paper,PID algorithm is adopted. Simulation

  16. Validation of CFC-12 measurements from the Improved Limb Atmospheric Spectrometer (ILAS) with the version 6.0 retrieval algorithm

    NASA Astrophysics Data System (ADS)

    Khosrawi, F.; Müller, R.; Irie, H.; Engel, A.; Toon, G. C.; Sen, B.; Aoki, S.; Nakazawa, T.; Traub, W. A.; Jucks, K. W.; Johnson, D. G.; Oelhaf, H.; Wetzel, G.; Sugita, T.; Kanzawa, H.; Yokota, T.; Nakajima, H.; Sasano, Y.

    2004-03-01

    Measurements of CFC-12 were made by the Improved Limb Atmospheric Spectrometer (ILAS) between 57°N and 72°N in the Northern Hemisphere and between 64°S and 89°S in the Southern Hemisphere. ILAS was launched on 17 August 1996 on board the Advanced Earth Observing Satellite (ADEOS). The ILAS validation balloon campaigns were carried out from Kiruna, Sweden (68°N, 21°E), in February and March 1997 and from Fairbanks, Alaska (65°N, 148°W), in April and May 1997. During these validation balloon campaigns, CFC-12 was measured with the in situ instruments ASTRID, BONBON, and SAKURA and the remote sensing spectrometers MIPAS-B, FIRS-2, and MkIV. ILAS version 6.0 CFC-12 profiles obtained at the nearest location to the validation balloon measurement are compared with these validation balloon measurements. The quality of ILAS CFC-12 data processed with the version 6.0 algorithm improved significantly compared to previous versions. Low relative differences between ILAS CFC-12 and the correlative measurements of about 10% were found between 13 and 20 km. The comparison of vertical profiles shows that ILAS CFC-12 data are useful below about 20-22 km inside the vortex and below about 25 km outside the vortex. However, at greater altitudes the relative percentage difference increases very strongly with increasing altitude. Further, correlations of CFC-12 with N2O show a good agreement with the correlative measurements for N2O values of N2O > 150 ppbv. In summary, ILAS CFC-12 data are now suitable for scientific studies in the lower stratosphere.

  17. 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.

  18. Texture Compensation for Haptic Feedback Signal Compression

    E-print Network

    Steinbach, Eckehard

    data and significantly raise storage and transmission requirements. Offline haptic coding algorithms [1Texture Compensation for Haptic Feedback Signal Compression Fernanda Brandi, Rahul Chaudhari {fernanda.brandi, rahul.chaudhari, eckehard.steinbach}@tum.de Abstract--Recently proposed haptic offline

  19. 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.

  20. Compensation for hearing loss.

    PubMed

    Dobie, R A

    1996-01-01

    Monetary compensation for occupational hearing loss in the U.S.A. is governed by at least 57 different state and federal systems. Costs of compensation are difficult to estimate. Most U.S. jurisdictions use the 1979 AMA Method, based on pure-tone thresholds, to determine the amount of compensation. Clinical data and epidemiological models can provide useful estimates of the relative contributions of occupational noise exposure, aging, and other causes. PMID:8790866

  1. A new algorithm for the retrieval of atmospheric diffuse transmittance in Moderate Resolution Imaging Spectroradiometer (MODIS) atmospheric correction: a study in the Bohai Sea

    Microsoft Academic Search

    Yahao Liu; Yuguang Liu; Yanzhen Gu; Xueyuan Liu; Yan He

    2010-01-01

    Based on 183 groups of in situ data measured with a spectroradiometer during 2003–2007 in the Bohai Sea, we calculated the atmospheric direct transmittance T, diffuse transmittance t, Ångström exponent ? and turbidity coefficient ? of aerosol optical thickness, and aerosol multiple forward scattering factor Ba. An empirical formula relating Ba with the two Ångström parameters, ? and ?, is

  2. Compensation of Printer MTFs

    Microsoft Academic Search

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

    ABSTRACT Preliminary experiments have shown that the quality of printed images depends on the capacity of the printing system to accurately reproduce details.,) 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

  3. An Algorithm for Retrieving Water Vapor Profiles in Clear and Cloudy Atmospheres from 183 GHz Radiometric Measurements: Simulation Studies

    Microsoft Academic Search

    Thomas T. Wilheit

    1990-01-01

    The latent heat represented by atmospheric water vapor is extremely important to the energetics of the Earth system. Future satellite (NOAA and DMSP) will carry microwave radiometers designed to measure the profile of water vapor globally. The problem of retrieving water vapor from the measurements is highly nonlinear even in clear atmospheres and the addition of clouds only makes it

  4. Atmospheric correction of visible to middle-infrared EOS-MODIS data over land surfaces: Background, operational algorithm and validation

    Microsoft Academic Search

    E. F. Vermote; N. El Saleous; C. O. Justice; Y. J. Kaufman; J. L. Privette; L. Remer; J. C. Roger; D. Tanré

    1997-01-01

    The NASA moderate resolution imaging spectroradiometer (MODIS) instrument will provide a global and improved source of information for the study of land surfaces with a spatial resolution of up to 250 m. Prior to the derivation of various biophysical parameters based on surface reflectances, the top of the atmosphere signals need to be radiometrically calibrated and corrected for atmospheric effects.

  5. 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.

  6. New optical compensator for higher-order polarization mode dispersion in optical fiber channels

    Microsoft Academic Search

    Chuanchuan Yang; Ziyu Wang

    2006-01-01

    We propose a new optical compensator for both first-order and higher-order polarization mode dispersion (PMD) effects in an optical fiber channel. The compensation scheme needs just one more polarization controller and one more variable differential group delay (DGD) element than first-order optical compensators with adjustable DGD elements. And the control algorithm for this compensator is easier and more stable than

  7. Reactive power compensator

    DOEpatents

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

    1992-01-01

    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.

  8. 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.

  9. 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.

  10. Adaptive optics compensation using active illumination

    Microsoft Academic Search

    Charles Higgs; Herbert T. Barclay; J. Kansky; Daniel V. Murphy; Charles A. Primmerman

    1998-01-01

    We have conducted atmospheric compensation experiments using active illumination for both adaptive-optics and tracking. Tests were performed in support of the Air Force's Airborne Laser program. The tests utilized the 5.4-km horizontal propagation range at the Lincoln Laboratory Firepond facility. The adaptive-optics beacon was provided by actively illuminating the target with a multibeam laser illuminator. A second multibeam laser illuminator

  11. Precision single-axis motion control system with friction compensation

    Microsoft Academic Search

    A. El-Roy; B. Friedland

    1995-01-01

    A high-speed position control system that achieves an accuracy of microns is described. The system, based on a printer mechanism, uses a linear encoder with 1000 lines per inch as the sensor and an interpolation scheme to achieve higher accuracy. The control algorithm uses the friction compensation algorithm developed by Friedland et. al. to eliminate hangoff and stick-slip. The system

  12. 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.

  13. Improving atmospheric correction for highly productive coastal waters using the short wave infrared retrieval algorithm with water-leaving reflectance constraints at 412 nm.

    PubMed

    Oo, Min; Vargas, Marco; Gilerson, Alex; Gross, Barry; Moshary, Fred; Ahmed, Sam

    2008-07-20

    The recently developed short wave infrared (SWIR) atmospheric correction algorithm for ocean color retrieval uses long wavelength channels to retrieve atmospheric parameters to avoid bright pixel contamination. However, this retrieval is highly sensitive to errors in the aerosol model, which is magnified by the higher variability of aerosols observed over urban coastal areas. While adding extra regional aerosol models into the retrieval lookup tables would tend to increase retrieval error since these models are hard to distinguish in the IR, we explore the possibility that for highly productive waters with high colored dissolved organic matter, an estimate of the 412 nm channel water-leaving reflectance can be used to constrain the aerosol model retrieval and improve the water-leaving reflectance retrieval. Simulations show that this constraint is particularly useful where aerosol diversity is significant. To assess this algorithm we compare our retrievals with the operational SeaWiFS Data Analysis System (SeaDAS) SWIR and near infrared retrievals using in situ validation data in the Chesapeake Bay and show that, especially for absorbing aerosols, significant improvement is obtained. Further insight is also obtained by the intercomparison of retrieved remote sensing reflectance images at 443 and 551 nm, which demonstrates the removal of anomalous artifacts in the operational SeaDAS retrieval. PMID:18641754

  14. A joint effort to deliver satellite retrieved atmospheric CO2 concentrations for surface flux inversions: the ensemble median algorithm EMMA

    NASA Astrophysics Data System (ADS)

    Reuter, M.; Bösch, H.; Bovensmann, H.; Bril, A.; Buchwitz, M.; Butz, A.; Burrows, J. P.; O'Dell, C. W.; Guerlet, S.; Hasekamp, O.; Heymann, J.; Kikuchi, N.; Oshchepkov, S.; Parker, R.; Pfeifer, S.; Schneising, O.; Yokota, T.; Yoshida, Y.

    2012-09-01

    We analyze an ensemble of seven XCO2 retrieval algorithms for SCIAMACHY and GOSAT. The ensemble spread can be interpreted as regional uncertainty and can help to identify locations for new TCCON validation sites. Additionally, we introduce the ensemble median algorithm EMMA combining individual soundings of the seven algorithms into one new dataset. The ensemble takes advantage of the algorithms' independent developments. We find ensemble spreads being often <1 ppm but rising up to 2 ppm especially in the tropics and East Asia. On the basis of gridded monthly averages, we compare EMMA and all individual algorithms with TCCON and CarbonTracker model results (potential outliers, north/south gradient, seasonal (peak-to-peak) amplitude, standard deviation of the difference). Our findings show that EMMA is a promising candidate for inverse modeling studies. Compared to CarbonTracker, the satellite retrievals find consistently larger north/south gradients (by 0.3 ppm-0.9 ppm) and seasonal amplitudes (by 1.5 ppm-2.0 ppm).

  15. ALGORITHM AND SOFTWARE DEVELOPMENT OF ATMOSPHERIC MOTION VECTOR (AMV) PRODUCTS FOR THE FUTURE GOES-R ADVANCED BASELINE IMAGER (ABI)

    Microsoft Academic Search

    Jaime Daniels; Chris Velden; Wayne Bresky; Iliana Genkova; Steve Wanzong

    Atmospheric motion vectors (AMVs), derived from the current GOES series of satellites, provide invaluable tropospheric wind information to the meteorological community. AMVs obtained from tracking features (i.e., clouds and moisture gradients) are used for: i) Improving numerical weather prediction (NWP) analyses and forecasts; ii) Supporting short term forecasting activities at National Weather Service (NWS) field offices; and iii) Generating tropical

  16. 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.

  17. Compensating springback in the automotive practice using MASHAL

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

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

  18. Compensating For Unbalance In Pulse-Code Phase Modulation

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien M.; Hinedi, Sami M.

    1995-01-01

    Algorithm proposed for use in pulse-code phase-modulation transmitter in which non-return-to-zero (NRZ) or biphase data modulated directly onto radio-frequency residual carrier signal. Devised to compensate somewhat for effect, upon distant receiver, of unbalance in stream of transmitted data. Formulated to compute combinations of modulation index, data rate, and transmitter power compensating for measured unbalance in transmitted data stream.

  19. Water quality monitoring by thematic mapper in coastal environments. A performance analysis of local biooptical algorithms and atmospheric correction procedures

    Microsoft Academic Search

    S. Tassan; M. R. dAlcala

    1993-01-01

    The Thematic Mapper (TM) sensor's ability to monitor localized phenomena associated with anthropogenic pollution in coastal waters has been investigated with reference to experimental data collected on a test site in the Gulf of Naples. In situ measurements yielded the biooptical algorithms for chlorophyll and sediment retrieval as well as an optical model for the computation of the subsurface reflectance

  20. 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…

  1. 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).

  2. Regulatory constraints on executive compensation

    E-print Network

    Joskow, Paul L.

    1993-01-01

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

  3. 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.

  4. Density compensation in island avifaunas

    Microsoft Academic Search

    S. Joseph Wright

    1980-01-01

    This paper analyzes factors which determine the extent of density compensation on islands; i.e., is the summed population density of all species on an island equal to the summed mainland density? A graphical analysis allows quantitative comparisons of density compensation studies. Two hypotheses which are generally applicable predict the extent of density compensation on islands: (1) Niche theory predicts that

  5. 2007 CEO Compensation Study

    NSDL National Science Digital Library

    2007-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  7. Research on the dynamic compensation based on genetic wavelet neural networks for the robot wrist force sensor

    Microsoft Academic Search

    Yu A-long

    2010-01-01

    A kind of new dynamic compensation method is presented based on improved genetic algorithm (IGA) and wavelet neural networks (WNN) and the principle of algorithm is introduced for a new type robot wrist force sensor. In this method, the dynamic compensation model of the wrist force sensor can be set up according to measurement data of the dynamic calibration, where

  8. Modified split-step fourier method for compensation of nonlinear fibre impairments

    Microsoft Academic Search

    Danish Rafique; Marco Mussolin; Marco Forzati; Jonas Martensson; Mohsan N. Chugtai; Andrew D. Ellis

    2011-01-01

    In this paper, we investigate a modified split-step Fourier method to enable computationally-efficient digital nonlinearity compensation for a coherently-detected 112 Gb\\/s polarization multiplexed quadrature phase shifted keying transmission over a 1,600 km link (20×80 km) with no inline compensation. We report up to 80% reduction in required stages to perform nonlinear compensation, in comparison to the conventional backpropagation algorithm. This

  9. An efficient error compensation system for CNC multi-axis machines

    Microsoft Academic Search

    Shih-Ming Wang; Yuan-Liang Liu; Yuan Kang

    2002-01-01

    To enhance a machine’s ability for a precision machining task, an efficient compensation scheme that takes all error sources into account is needed. In this study, an effective static\\/quasi-static error compensation system composed of an interpolation algorithm based on shape functions for error prediction, and a recursive software compensation procedure, was developed. The new error prediction scheme is efficient enough

  10. Compensating the island network voltage unsymmetricity with DTC-modulation-based power conditioning system

    Microsoft Academic Search

    Antti Tarkiainen; Riku Pöllänen; Markku Niemelä; Juha Pyrhönen; Mikko Vertanen

    2004-01-01

    An algorithm for compensating island network voltage unsymmetricity with a direct torque control modulation-based scalar-controlled power conditioning system is introduced and experimentally verified. The proposed method consists of two separate stages where at first the unsymmetricity is detected and then a compensating negative-sequence system is calculated. Experimental results show that the proposed method fully compensates the voltage unsymmetricity resulting from

  11. Self-compensating tensiometer and method

    DOEpatents

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

    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.

  12. 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.

  13. Discontinuous piecewise parametric modeling and compensation control for manipulator systems with friction

    Microsoft Academic Search

    Xiaohua Lv; Dongwu Li; Xuemei Ren

    2011-01-01

    A novel compensation control based on intelligent modeling for joint friction in manipulator systems is proposed in this paper. The modeling algorithm exploits the discontinuous piecewise parametric representation (DPPR) as the estimator of generalized friction while the controller is a non-model feedforward compensator. The DPPR modeling captures the main characteristics of friction including Stribeck effect, discontinuous at zero, Coulomb and

  14. Refined Motion Compensation for Highly Squinted Spotlight Syn-thetic Aperture Radar

    E-print Network

    Refined Motion Compensation for Highly Squinted Spotlight Syn- thetic Aperture Radar Minh Phuong which is capable of dealing with large motion errors for highly squinted spotlight SAR. The approach/resampling in azimuth. For pulsed SAR with a 30° squint angle, the proposed algorithm compensates motion errors

  15. Robust adaptive numerical compensation for friction and force ripple in permanent-magnet linear motors

    Microsoft Academic Search

    K. K. Tan; S. N. Huang; T. H. Lee

    2002-01-01

    This paper describes a robust adaptive compensation method for friction and force ripple present in the dynamics of permanent-magnet linear motors. The method is used in ultraprecise positioning applications. The compensation algorithm consists of a PID component and an adaptive component for estimating friction and force ripple. The adaptive component is continuously refined on the basis of just prevailing input

  16. Design of ground motion compensation servo system

    NASA Astrophysics Data System (ADS)

    Tan, Chan; Ding, Lei; Chai, Jinguang

    2013-05-01

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

  17. Dosage compensation in Drosophila.

    PubMed

    Lucchesi, John C; Kuroda, Mitzi I

    2015-05-01

    Dosage compensation in Drosophila increases the transcription of genes on the single X chromosome in males to equal that of both X chromosomes in females. Site-specific histone acetylation by the male-specific lethal (MSL) complex is thought to play a fundamental role in the increased transcriptional output of the male X. Nucleation and sequence-independent spreading of the complex to active genes serves as a model for understanding the targeting and function of epigenetic chromatin-modifying complexes. Interestingly, two noncoding RNAs are key for MSL assembly and spreading to active genes along the length of the X chromosome. PMID:25934013

  18. Laser Wavefront Compensation System

    NASA Astrophysics Data System (ADS)

    Hardy, John W.

    1988-04-01

    The laser wavefront compensation system (LWCS) is a closed-loop adaptive optics sytem whose purpose is to clean up optical aberrations in low power visible laser beams. The LWCS employs no moving parts and operates with either continuous-wave (CW) or pulsed inputs. In the pulsed mode, it will operate asynchronously over a wide range of pulse rates. The electronic data processing is entirely digital, including the wavefront reconstruction function. The deformable mirror employs a square array of 64 actuators, with a wavefront correction capability of ±600 nanometers. This paper describes the operating principles and hardware of the LWCS, together with data on the performance of the system.

  19. Stereo-Based Head Pose Tracking with Motion Compensation Model

    Microsoft Academic Search

    Z. G. Liu; Y. F. Li; Paul Bao

    2004-01-01

    We present a stereo based head tracking algorithm with motion error compensation model. We firstly reconstruct 3D head model by coupling feature tracking with the epipolar constraint from the stereo image pair. Based on the reconstructed 3D model, we can obtain the coarse 3D pose of the head at this point. We then analyze the errors in the estimation of

  20. Path Following with Slip Compensation for a Mars Rover

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  1. 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.

  2. Laser Gyro Temperature Compensation Using Modified RBFNN

    PubMed Central

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

    2014-01-01

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

  3. Dispersion Compensating Fibers

    NASA Astrophysics Data System (ADS)

    Grüner-Nielsen, Lars; Knudsen, Stig Nissen; Edvold, Bent; Veng, Torben; Magnussen, Dorte; Larsen, C. Christian; Damsgaard, Hans

    2000-04-01

    The basic principles for use of dispersion compensating fibers (DCF) are reviewed, including definition of figure of merit and condition for dispersion slope compensation. The main design features of a triple-cladding index profile design are examined theoretically and experimentally. Production results are presented for three types of DCF. It is shown that polarization-mode dispersion can be reduced by introducing oscillatory twist into the fiber. The splice loss between DCF and standard fibers is shown to be reducible by use of a special intermediate fiber. Two methods for measuring the nonlinear effective area of DCF are compared and good agreement is found. Measurement results for the nonlinear refractive index n2 are reported. The nonlinear coefficient n2/ Aeff of DCF is found to be a factor of 5 higher than that on standard single-made fibers. The macrobending resistance of DCF is examined and found to be comparable with that of standard fibers. The microbending resistance of DCF is found to be better than that of standard fibers. Finally, positive results from a cabling experiment with DCF are reported.

  4. Compensation for occupational cancer.

    PubMed

    Kim, Inah; Kim, Eun-A; Kim, Jae Young

    2014-06-01

    The legal scope and criteria for occupational cancer in Korea was out of date. The aim of this study was to review the current criteria for occupational cancer and amend the existent criteria on the basis of recent scientific evidence. The scientific evidence and the legal list of occupational cancer were analyzed to identify the causes of occupational cancer on a global scale. The relationship between compensated occupational cancer cases and carcinogen exposure in Korea was examined. The factors associated with specific causes and target cancers were determined to produce additional criteria. Five-hundred and nineteen cases of 2,468 were awarded compensation for occupational cancer including lung, malignant mesothelioma, lymphohematopoietic, and liver cancers from January 2000 to October 2012. Between 1996 and 2005, benzene accounted for 84.4% of cases, and between 1999 and 2005, asbestos was associated with 62.3% of cases. Fourteen novel causative agents and 12 additional target cancers were identified and the final guidelines were amended to include 23 causative agents and 21 target cancers. This amendment of the criteria for occupational cancer represents the widest change in Korean history and is expected to improve the understanding of occupational cancer by providing an up-to-date and accurate reference guide. PMID:25006323

  5. Fast backprojection algorithm for UWB bistatic SAR

    Microsoft Academic Search

    Viet T. Vu; Thomas K. Sjogren; Mats I. Pettersson

    2011-01-01

    The paper introduces an algorithm for Ultrawide- band Ultrawidebeam (UWB) bistatic Synthetic Aperture Radar (SAR). The algorithm works in time-domain and therefore inherits time-domain characteristics such as unlimited scene size, local processing and manageable motion compensation. The proposed algorithm is not limited by any configuration of bistatic SAR. The algorithm processes the UWB bistatic SAR data on a subaperture and

  6. 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

  7. Atmospheric illumination and shadows

    Microsoft Academic Search

    Nelson L. Max

    1986-01-01

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

  8. Fixman compensating potential for general branched molecules

    PubMed Central

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

    2013-01-01

    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

  9. Fixman compensating potential for general branched molecules

    SciTech Connect

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

    2013-12-28

    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.

  10. Summing pressure compensation control

    SciTech Connect

    Myers, H.A.

    1988-04-26

    This patent describes a summing pressure compensator control for hydraulic loads with at least one of the hydraulic loads being a variable displacement motor having servo means for controlling the displacement thereof, first hydraulic means responsive to the supply of fluid to the variable displacement motor to provide a first pressure signal, second hydraulic means responsive to the supply of fluid to a second hydraulic load to provide a second pressure signal, summing means for receiving the first and second pressure signals and providing a control signal proportional to the sum of the first and second pressure signals, the control signal being applied to the servo means to increase the displacement of the variable displacement motor.

  11. Automatic compensation of nonlinear distortions

    Microsoft Academic Search

    Tamas B. Bakol; Tamás Dabóczi; Barry A. Bell

    2002-01-01

    When a signal passes a system having a static, nonlinear transfer function, the output signal will be distorted. In addition to it, the defected output signal is usually contaminated by noise, due to the noisy environment. If the distortion level of the signal is not acceptable, we have to compensate it. This should be done carefully, because an improper compensation

  12. Corporate governance and executive compensation

    Microsoft Academic Search

    Martin J. Conyon

    1997-01-01

    This paper examines the impact of corporate governance innovations on top director compensation in a sample of 213 large UK companies between 1988 and 1993. An enabling factor in the analysis is access to survey data on recent corporate governance changes in UK companies. The paper finds that director compensation and current shareholder returns are positively correlated. However, in line

  13. Primary-care physician compensation.

    PubMed

    Olson, Arik

    2012-01-01

    This article reviews existing models of physician compensation and presents information about current compensation patterns for primary-care physicians in the United States. Theories of work motivation are reviewed where they have relevance to the desired outcome of satisfied, productive physicians whose skills and expertise are retained in the workforce. Healthcare reforms that purport to bring accountability for healthcare quality and value-rather than simply volume-bring opportunities to redesign primary-care physician compensation and may allow for new compensation methodologies that increase job satisfaction. Physicians are increasingly shunning the responsibility of private practice and choosing to work as employees of a larger organization, often a hospital. Employers of physicians are seeking compensation models that reward both productivity and value. PMID:22786738

  14. 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

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

    E-print Network

    de Vries, Geert J.

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

  16. Dynamic PMD compensation in 40-Gb/s optical communication system

    NASA Astrophysics Data System (ADS)

    Li, Tangjun; Wang, Muguang; Jian, Shuisheng; Lou, Caiyun; Huo, Li; Yao, Hejun; Ning, Tigang; Cui, Jie; Yang, Fangcheng; Diao, Cao; Gong, Xiangfeng; Fu, Yongjun; Tan, Zhongwei; Liu, Yan

    2005-05-01

    A 40-Gb/s optical time division multiplexing (OTDM) return-to-zero (RZ) transmission experiments including a dynamic polarization mode dispersion (PMD) compensation was reported. The dynamic PMD compensator is made up of two-stage four degrees of freedom (DOF). The first stage adopts polarization controller and fixed time-delayed line. The second stage is variable differential group delay (DGD) element. The PMD monitoring technique is based on degree of polarization (DOP) as error signal. A novel practical adaptive optimization algorithm was introduced in dynamic adaptive PMD compensation. The experimental results show that the performance of the PMD compensator is excellent for 40-Gb/s RZ transmission systems with the large DGD. With this compensator, a significant improvement of system performance can be achieved in the eye pattern of a received signal. The first-order compensating ability of the compensator is greater than 30 ps. The second-order compensating ability is greater than 200 ps2. The first-order optimum compensating time is within 10 ms. The second-order optimum compensating time is within 24 ms.

  17. Convection compensated electrophoretic NMR.

    PubMed

    He, Q; Wei, Z

    2001-06-01

    A novel method of convection compensated ENMR (CC-ENMR) has been developed to detect electrophoretic motion of ionic species in the presence of bulk solution convection. This was accomplished using a gradient moment nulling technique to remove spectral artifacts from heat-induced convection and using the polarity switch of the applied electric field to retain spin phase modulations due to electrophoretic flow. Experiments were carried out with a mixture of 100 mM L-aspartic acid and 100 mM 4,9-dioxa-1,12-dodecanediamine to demonstrate this new method of ENMR. CC-ENMR enhances our previously developed capillary array ENMR (CA-ENMR) in solving the convection problem. The combined CA- and CC-ENMR approach strengthens the potential of multidimensional ENMR in simultaneous structural determination of coexisting proteins and protein conformations in biological buffer solutions of high ionic strength. Structural mapping of interacting proteins during biochemical reactions becomes possible in the future using ENMR techniques, which may have a profound impact on the understanding of biological events, including protein folding, genetic control, and signal transduction in general. PMID:11384170

  18. Compensated pulsed alternator

    SciTech Connect

    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.

  19. Computing planetary atmospheres with algorithms derived from action thermodynamics and a novel version of the virial theorem for gravitating polyatomic molecules

    E-print Network

    Kennedy, Ivan R

    2015-01-01

    An objective revision of the Laplace barometric formula for isothermal planetary atmospheres is proposed. From Clausius virial theorem equating the root mean square kinetic energy to half the gravitational potential energy, planetary atmospheres are required to have declining temperature with altitude as a consequence of the interaction between thermodynamic heat flow and gravity. The virial action hypothesis predicts non adiabatic lapse rates in temperature yielding a practical means to calculate variations with altitude in atmospheric entropy, free energy, molecular density and pressure. Remarkably, the new formulae derived enable prediction of atmospheric profiles with physical properties closely resembling those observed on Earth, Venus and Mars. These new formulae provide an objective basis for computing the dynamic morphology of the atmosphere. Climate scientists may consider this explanatory hypothesis for self organisation of planetary atmospheres for its possible relevance for predicting global surfa...

  20. Perks and Culture Competitive compensation

    E-print Network

    Ghosh, Joydeep

    Perks and Culture · Competitive compensation · Health coverage and wellness program · 401(k) plan path with a variety of new jobs and skills · Active recent graduate community · Diversity and inclusion

  1. Analysis of motion compensation and an implementation solution for airborne SAR system

    NASA Astrophysics Data System (ADS)

    Su, Hongyu; Long, Teng; He, Peikun

    2001-09-01

    Motion compensation of airborne synthetic aperture radar (SAR) consists of motion compensation based on inertial navigation system (INS) and autofocus algorithms. This paper deeply analyzes both the two aspects on the principle and gives the implementation solution. By the motion compensation based on INS, it gives not only the influence of the precision but also the effect of the data rate and points out that the data rate of the INS is the same important as the precision of INS for better result of motion compensation. Because of its excellent compensation ability and wide compensation scope, phase gradient autofocus (PGA) is used as an effective algorithm to do autofocus work. Based on the principle of PGA, the detail approach and simulation result is presented. Additionally, this paper also points out that the bottle-neck of the real time imaging processing of airborne SAR is not the computing capacity of the processing chip but the amount of memorize of the system. Then it gives an implementation solution for airborne SAR system by using high speed DSPs and huge amount memorize, with which the real time signal processing of the imaging algorithm combined with the motion compensation can be realized.

  2. National Compensation Survey Home Page

    NSDL National Science Digital Library

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

  3. 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.

  4. 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%.

  5. Reactive power compensation for wind power plants

    Microsoft Academic Search

    E. H. Camm; M. R. Behnke; O. Bolado; M. Bollen; M. Bradt; C. Brooks; W. Dilling; M. Edds; W. J. Hejdak; D. Houseman; S. Klein; F. Li; J. Li; P. Maibach; T. Nicolai; J. Patino; S. V. Pasupulati; N. Samaan; S. Saylors; T. Siebert; T. Smith; M. Starke; R. Walling

    2009-01-01

    This technical paper provides the basic guidelines for the application of reactive compensation systems to be used as part of a wind power plant. A brief history of wind plant reactive compensation system is discussed, then the fundamental needs of why reactive compensation is required. The paper will then provide some alternatives for reactive compensation, how to size the reactive

  6. Active Heave Crown Compensation SubSystem

    Microsoft Academic Search

    J. T. Hatleskog; M. W. Dunnigan

    2007-01-01

    This paper outlines an active heave compensation system used in conjunction with a crown mounted compensator. The objective is to reduce the heave disturbance at the suspended load above sea floor using an active sub-system comprising controller, sensors and a suitable hydraulic power unit driving an actuator attached to the compensator. In this case the compensator system behaves much like

  7. Atmospheric and adaptive optics

    NASA Astrophysics Data System (ADS)

    Hickson, Paul

    2014-11-01

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

  8. Improved environmental corrections for compensated neutron logs

    SciTech Connect

    Galford, J.E.; Flaum, C.; Gilchrist, W.A. Jr.; Soran, P.D.; Gardner, J.S.

    1988-06-01

    The basic openhole responses and environmental correction algorithms for compensated neutron logging (CNL) tools have been updated. The improved processing is based on an extensive set of laboratory formation measurements to which mathematical modeling calculations have been added. In all, the new algorithms include basic responses for the three principal formation matrix types and corrections for seven environmental effects and formation-fluid salinity. A total of 467 laboratory formation measurements have been augmented with 245 data points generated through mathematical modeling. This data base has been used to define more accurately the effects on the tool response of variations in logging conditions from those considered standard in the laboratory. More accurate corrections for the effects of formation pressure, temperature, mudcake, natural or barite mud, and borehole salinity have been defined. Certain other effects depend on more than one parameters. For example, the effect of formation salinity is somewhat matrix-dependent; therefore, the corrections are handled differently for sandstone, limestone, and dolomite. The effect of tool standoff depends on the borehole size; consequently, the standoff correction is larger for larger boreholes. The porosity crossplots and environmental correction charts based on the new algorithms represent a significant evolutionary improvement over previous techniques. They should be an important aid to the use and interpretation of neutron logs.

  9. Numerical analysis of the scaling parameter of adaptive compensation for thermal blooming effects

    NASA Astrophysics Data System (ADS)

    Huang, Yinbo; Wang, Yingjian; Gong, Zhiben

    2002-09-01

    By using the time-dependent propagation computer code, adaptive compensation for thermal blooming effects, which are induced by collimated high-energy laser (HEL) beam propagation through the atmosphere, is numerically calculated and analyzed under different conditions. The numerical results show that, with the definite adaptive optics (AO) system, the scaling parameter ND/NFB is available to evaluate the effect of adaptive compensation efficiently. Moreever, we get the scaling relation between the scaling parameter ND/NFB and the far-field Strehl ratio, which is can be described by Strehlequals1/[1+AND/NFB+B(ND/NFB)C], where A, B and C are fitting parameters. We also get the threshold of adaptive phase compensation instability (PCI) through analysis of the scaling rotation above. In addition, we discuss the difference between adaptive compensation and whole-beam compensation.

  10. 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

  11. Compensating For Changes in MOS Sensors

    SciTech Connect

    Matzke, Brett D.

    2006-09-29

    AirAdvice provided the following introduction: “AirAdvice uses metal oxide semiconductor (MOS) sensors for measuring total volatile organic compounds (TVOC) in air. These sensors are incorporated into AirAdvice’s indoor air quality (IAQ) monitors. The IAQ monitors are designed so that they require annual calibration to maintain acceptable accuracy. Since the MOS TVOC sensors used in the monitors change in sensitivity with time and exposure to gases, AirAdvice has developed an algorithm-based process that automatically compensates for changes in the sensors. The proposed project is to have PNNL analyze data provided by AirAdvice with these objectives: (1) assess how effective AirAdvice’s automatic drift correction process is, (2) identify any problems in the process, and (3) propose improvements to the process.”

  12. 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

  13. Motion-compensated subband coding with scene adaptivity

    NASA Astrophysics Data System (ADS)

    Lee, Jungwoo; Dickinson, Bradley W.

    1994-05-01

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

  14. 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.

  15. Compensating for pneumatic distortion in pressure sensing devices

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.; Leondes, Cornelius T.

    1990-01-01

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

  16. 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...indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief...

  17. 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...indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief...

  18. 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...indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief...

  19. 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...indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief...

  20. 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...indemnity compensation, death compensation, pension and spouse's compensation ratings. 3.351 Section 3.351 Pensions, Bonuses, and Veterans' Relief...

  1. Comparison of motion-compensated reconstruction with FBP and BPF for circular X-ray tomography: A simulation study

    Microsoft Academic Search

    Dirk Schafer; Michael Grass

    2011-01-01

    We present two new approximate variants of motion-compensated 3D back-projection filtration (MC-BPF) algorithms for circular cone-beam X-ray tomography in divergent beam geometry. The first one uses differentiation in a single projection (SD), while the second one is based on the Katsevich-type differentiation (KD) involving two neighboring projections. The BPF-type algorithms are compared to an approximate 3D motion-compensated filtered back-projection (MC-FDK)

  2. A convolution algorithm to calculate differential cross sections of the Ring effect in the Earth’s atmosphere based on rotational Raman scattering

    Microsoft Academic Search

    Dong Han; LiangFu Chen; Lin Su; JinHua Tao; ShenShen Li; Chao Yu; Ying Zhang; BaoHua He

    The Ring effect refers to the filling in of Fraunhofer lines, which is mainly attributed to the rotational Raman scattering\\u000a of solar spectra by N2 and O2 molecules in the atmosphere. The Ring effect is one of the most significant factors affecting the accuracy of retrieving\\u000a concentrations of atmospheric trace gases, such as NO2 and SO2, from satellite observations through

  3. Invertible temporal subband\\/wavelet filter banks with half-pixel-accurate motion compensation

    Microsoft Academic Search

    Shih-ta Hsiang; John W. Woods; Jens-rainer Ohm

    2004-01-01

    Three-dimensional (3-D) subband\\/wavelet coding with motion compensation has been demonstrated to be an efficient technique for video coding applications in some recent research works. When motion compensation is performed with half-pixel accuracy, images need to be interpolated in both temporal subband analysis and synthesis stages. The resulting subband filter banks developed in these former algorithms were not invertible due to

  4. A new high-efficiency error compensation system for CNC multi-axis machine tools

    Microsoft Academic Search

    Shih-Ming Wang; Han-Jen Yu; Hung-Wei Liao

    2006-01-01

    To enhance the accuracy of CNC machines for the request of modern industry, an effective static\\/quasi-static error compensation\\u000a system composed of an element-free interpolation algorithm based on the Galerkin method for error prediction, a recursive\\u000a software compensation procedure, and an NC-code converting software, is developed. Through automatically analyzing the machining\\u000a path, the new error prediction method takes into consideration the

  5. Chromatic dispersion profile optimization of dual-concentric-core photonic crystal fibers for broadband dispersion compensation

    Microsoft Academic Search

    Takeshi Fujisawa; Kunimasa Saitoh; Keisuke Wada; Masanori Koshiba

    2006-01-01

    Chromatic dispersion profile of dual-concentric-core photonic crystal fibers is optimized for broadband dispersion compensation of single mode fibers (SMFs) by using genetic algorithm incorporated with full-vector finite-element method. From the numerical results presented here, it is found that by increasing the distance between central core and outer ring core, larger negative dispersion coefficient and better dispersion slope compensation are possible.

  6. Compensating Customer-Generators: A taxonomy describing methods of compensating

    E-print Network

    Hughes, Larry

    their electricity demands (loads) (IEA, 2003; Lovins, 2003). This trend can be attributed to factors, compensation, small power producer. 1. Introduction A growing number of homeowners, small businesses, and small home or business will meet on-site loads using a combination of customer-generated electricity

  7. 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

  8. A resonant pressure microsensor capable of self-temperature compensation.

    PubMed

    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

  9. 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

  10. Research on machining error compensation in high-precision surface grinding machine for optical aspheric elements

    NASA Astrophysics Data System (ADS)

    Ke, Xiaolong; Guo, Yinbiao; Zhang, Shihan; Huang, Hao

    2010-10-01

    Using aspheric component in optical system can correct optical aberration, acquire high imaging quality, improve the optical characteristic, simplify system structure, and reduce system volume. Nowadays, high-precision surface grinding machine is an important approach to processing optical aspheric elements. However, because of the characteristics of optical aspheric elements, the processing method makes a higher demand to whole performance of surface grinding machine, and hardly to achieve ideal machining effect. Taking high generality and efficiency into account, this paper presents a compensation method for machining errors of high-precision surface grinding machine, which bases on optical aspheric elements, to achieve high-precision machining for all kinds of optical aspheric elements. After compensation, the machining accuracy of grinding machine could reach 2um/200×200mm. The research bases on NC surface grinding machine which is self developed. First of all, this paper introduces machining principle for optical aspheric elements on the grinding machine. And then error sources which producing errors are analyzed. By contacting and non-contacting measurement sensors, measurement software which is self designed realizes on-position measure for grinded workpiece, then fits surface precision and machining errors. Through compensation software for machining error which is self designed, compensation algorithm is designed and translated compensation data into G-code for the high-precision grinding machine to achieve compensation machining. Finally, by comparison between machining error compensation before and after processing, the experiments for this purpose are done to validate the compensation machining accuracy.

  11. 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.

  12. Compensation predicts smoking cessation failure

    PubMed Central

    Niaura, Raymond S.; Pearson, Jennifer L.; Abrams, David B.

    2013-01-01

    Rationale Compensation is a potential result of decreasing the available nicotine and tar dose in cigarettes. There is little published data linking compensation with cessation. Objectives We sought to examine whether compensation in response to restricted cigarette yield is associated with difficulty quitting smoking. Methods Questionnaires and blood samples were collected from 174 smokers interested in quitting smoking as part of a larger smoking cessation study. Participants were instructed to use a filter designed to remove 50% of tar and nicotine from the cigarette but otherwise smoke normally. Participants returned after three days of using the filter for follow up data collection. Results Nicotine levels and cigarettes per day decreased after use of the filter. Baseline nicotine and change in nicotine pre/post filter use, but not cigarettes per day or change in cigarettes per day, were associated with smoking abstinence at 30 days. Conclusions Smokers who demonstrate sensitivity to the biological or behavioral consequences of decreased nicotine content in tobacco smoke have greater difficulty quitting. These findings suggest the need for personalized cessation treatment linked to behavioral compensation. PMID:23748381

  13. Altitude Compensating Nozzle Concepts Evaluation

    NASA Technical Reports Server (NTRS)

    Soni, Bharat

    2000-01-01

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

  14. Compensating The Dead Marc Fleurbaeyy

    E-print Network

    Bou-Zeid, Elie

    Kaplan et al 1987), but those behavioural determinants of longevity (e.g. smoking, diet, physical in the life cycle. In a model with heterogeneous preferences and longevities, we show how a speci...c social various informational assumptions. Keywords: compensation, longevity, mortality, fairness, redistribution

  15. COMPENSATION: AN INTRODUCTION Howard Shapiro

    E-print Network

    Oliver, Douglas L.

    considers autofluorescence. It now appears that subtractive compensation is preferable... #12;HIGH-TECH@shapirolab.com Boston Users' Group for Cytometry September 10, 2003 Slides 2, 5, and 10-15 contain material from Shapiro HM: Practical Flow Cytometry, 4th Ed., © 2003 by John Wiley & Sons, Inc. Slide 3 contains material

  16. Synchrony - Cyberknife Respiratory Compensation Technology

    SciTech Connect

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

    2008-07-01

    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.

  17. Bird orientation: compensation for wind

    E-print Network

    Thorup, Kasper

    Bird orientation: compensation for wind drift in migrating raptors is age dependent Kasper Thorup1 14.04.03 Despite the potentially strong effect of wind on bird orientation, our understanding of how wind drift affects migrating birds is still very limited. Using data from satellite-based radio

  18. Perks and Culture Competitive compensation

    E-print Network

    Ghosh, Joydeep

    solutions to support the diverse businesses of Chevron Corporation. IT employees support a spectrumPerks and Culture · Competitive compensation · Relocation packages · Performance bonuses · 401(k) plan with company match and immediate vesting · Pension plan vested after 5 years · Employee referral

  19. Cellular Mechanisms of Vestibular Compensation

    Microsoft Academic Search

    Janet M. Paterson; John R. W. Menzies; Filip Bergquist; Mayank B. Dutia

    2006-01-01

    Vestibular compensation, the behavioral recovery that takes place after unilateral vestibular deafferentation, is a complex and multifactorial process involving synaptic and neuronal plasticity in the vestibular nuclei, cerebellum and related structures. Recent experimental evidence suggests that changes in the intrinsic properties of the vestibular nucleus neurons, changes in the efficacy of their inhibitory synaptic inputs, activity-dependent rewiring of synaptic connectivity

  20. Compensation of Navajo Uranium Miners

    NSDL National Science Digital Library

    World Information Service on Energy Uranium Project

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

  1. Performance of synchronous optical receivers using atmospheric compensation techniques

    E-print Network

    Kahn, Joseph M.

    . Barros, and J. M. Kahn, "Coherent detection in optical fiber systems," Opt. Express 16, 753-791 (2008). 9. M. P. Cagigal and V. F. Canales, "Speckle statistics in partially corrected wave fronts," Opt. Lett. 23, 1072- 1074 (1998). 10. J. W. Goodman, Speckle Phenomena in Optics. Theory and Applications (Ben

  2. 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.

  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. Measurements of atmospheric parameters using the SOR atmospheric monitor

    NASA Astrophysics Data System (ADS)

    Spillar, Earl J.

    2011-06-01

    We discuss the SOR Atmospheric Monitor's (SAM's) algorithms for estimating a number of atmospheric parameters from Shack-Hartmann wave front sensor measurements. In addition to the previously reported Fried parameter work, we report on estimates of Greenwood frequency and isoplanatic angle. We also report on a few months of statistics of these parameters at Kirtland AFB.

  5. 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…

  6. Atmospheric correction of multi-temporal mono-directional images : VENµS level 2 algorithms applied to Formosat-2 images

    Microsoft Academic Search

    O. Hagolle; H. Tromp; G. Dedieu; B. Mougenot; V. Simonneaux; B. Duchemin; I. Benhadj

    Usually, reflectance time series in the visible or near-infrared domain, such as those provided by SPOT satellites or by wide field of view instruments (VGT, MERIS, MODIS) are degraded by two geo-physical sources of variability: 1) atmospheric effects, mainly because of aerosol scattering, difficult to correct because Aerosol Optical Properties (AOP) are highly variable in time and place, 2) directional

  7. Avian sex chromosomes: dosage compensation matters. 

    E-print Network

    McQueen, Heather A; Clinton, Michael

    2009-01-01

    of such dosage compensated genes can be found on the short arm of the Z chromosome. The implications of this new picture of avian dosage compensation for avian sex determination are discussed, along with a possible mechanism of avian dosage compensation....

  8. Heave compensated stabbing and landing tool

    Microsoft Academic Search

    D. V. Johnson; J. A. Burkhardt; T. W. Childers

    1989-01-01

    This patent describes a heave compensated stabbing and landing tool for use on a vessel including a drill string compensator and a tubing string connected to the drill string compensator. It comprises: an upper tubing grip having a first engaged position in which it grips the tubing string and a second disengaged position; a lower tubing grip having a first

  9. Bankers' compensation and fair value accounting

    Microsoft Academic Search

    Gilad Livne; Garen Markarian; Alistair Milne

    2011-01-01

    This paper examines the role of certain fair value accounting (FVA) outcomes in compensation of US bank CEOs. The use of FVA in compensation invites an agency cost—the clawback problem—if cash compensation is based on unrealized profits that may reverse in the future. At the same time FVA may be a good measure of current managerial effort and so be

  10. Causal compensated perturbations in cosmology

    SciTech Connect

    Veeraraghavan, S.; Stebbins, A. (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA) California Univ., Berkeley (USA) Canadian Institute for Theoretical Astrophysics, Toronto (Canada))

    1990-12-01

    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. 55 refs.

  11. 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.

  12. 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.

  13. Adaptive beamformer delay compensation for active sonar

    NASA Astrophysics Data System (ADS)

    Alsup, James M.

    1994-10-01

    Delay compensation as a preliminary step to adaptive beamforming (ABF) is described. Such compensation can be used for linear or planar arrays whenever the temporal width of a signal's matched-filter output peak is significantly shorter than the propagation time across the array. Preliminary delay compensation is not normally used in passive ABF processing since the signals being processed are usually steady-state or can be regarded as such. However, when transient events much be processed, such as those associated with either impulsive echoes or with matched-filter outputs of large TW signals, then compensation prior to ABF may be required in order to obtain the full array gain for the signal of interest. Methods for achieving wide-band delay compensation are described, the parameters associated with defining the minimal compensation required are explained, and losses suffered when compensation is not used are discussed.

  14. Photorespiratory compensation: a driver for biological diversity.

    PubMed

    Sage, R F

    2013-07-01

    This paper reviews how terrestrial plants reduce photorespiration and thus compensate for its inhibitory effects. As shown in the equation ? = (1/Sc/o )O/C, where ? is the ratio of oxygenation to carboxylation, Sc/o is the relative specificity of Rubisco, O is stromal O2 level and C is the stromal CO2 concentration, plants can reduce photorespiration by increasing Sc/o or C, or by reducing O. By far the most effective means of reducing ? is by concentrating CO2, as occurs in C4 and CAM plants, and to a lesser extent in plants using a glycine shuttle to concentrate CO2 into the bundle sheath. Trapping and refixation of photorespired CO2 by a sheath of chloroplasts around the mesophyll cell periphery in C3 plants also enhances C, particularly at low atmospheric CO2. O2 removal is not practical because high energy and protein investment is needed to have more than a negligible effect. Sc/o enhancement provides for modest reductions in ?, but at the potential cost of limiting the kcat of Rubisco. An effective means of decreasing ? and enhancing carbon gain is to lower leaf temperature by reducing absorbance of solar radiation, or where water is abundant, opening stomata. By using a combination of mechanisms, C3 plants can achieve substantial (>30%) reductions in ?. This may have allowed many C3 species to withstand severe competition from C4 plants in low CO2 atmospheres of recent geological time, thereby preserving some of the Earth's floristic diversity that accumulated over millions of years. PMID:23656429

  15. Real-time compensation for tool form errors in turning using computer vision

    SciTech Connect

    Nobel, G.; Donmez, M.A.; Burton, R.

    1990-12-31

    Deviations from the circular shape of the cutting edge of a single-point turning tool cause form errors in the workpiece during contour cutting. One can compensate for these tool-form errors by determining the size of the effective deviation at a particular instant during cutting, and then adjusting the position of the cutting tool accordingly. An algorithm for the compensation of tool-nose-radius errors in real time has been developed and implemented on a CNC fuming center. A previously developed computer-vision-based tool- inspection system is used to determine the size of the deviations. Information from this system is fed to the error compensation computer which modifies the tool path in real time. Workpieces were cut utilizing the compensation system and were inspected on a coordinate measuring machine. Significant improvements in workpiece form were obtained.

  16. Multivariable adaptive algorithms for reconfigurable flight control

    Microsoft Academic Search

    Marc Bodson; Joseph E. Groszkiewicz

    1997-01-01

    The application of multivariable adaptive control techniques to flight control reconfiguration is considered. The objective is to redesign automatically flight control laws to compensate for actuator failures or surface damage. Three adaptive algorithms for multivariable model reference control are compared. The availability of state measurements in this application leads to relatively simple algorithms. The respective advantages and disadvantages of the

  17. 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.

  18. Transport delay compensation for computer-generated imagery systems

    NASA Astrophysics Data System (ADS)

    McFarland, Richard E.

    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.

  19. On choosing layer profiles in atmospheric tomography

    NASA Astrophysics Data System (ADS)

    Auzinger, Günter

    2015-04-01

    In control of the AO system of an ELT, most algorithms for atmospheric tomography are based on assuming atmospheric turbulence to occur only within a certain number of horizontal layers. The number of these layers is in general significantly smaller than the number of turbulent layers in the real atmosphere. We investigate the question, how the choice of the number and heights of the hypothetical layers (as parameters of the reconstruction algorithm) influences the resulting quality of the tomographic reconstruction.

  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. 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.

  2. 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.

  3. 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.

  4. Phase unwrapping for noisy phase map using localized compensator.

    PubMed

    Tomioka, Satoshi; Nishiyama, Shusuke

    2012-07-20

    Phase unwrapping for a noisy image suffers from many singular points. Singularity-spreading methods are useful for the noisy image to regularize the singularity. However, the methods have a drawback of distorting phase distribution in a regular area that contains no singular points. When the singular points are confined in some local areas, the regular region is not distorted. This paper proposes a new phase unwrapping algorithm that uses a localized compensator obtained by clustering and by solving Poisson's equation for the localized areas. The numerical results demonstrate that the proposed method can improve the accuracy compared with other singularity-spreading methods. PMID:22858936

  5. Accurate voltage phasor measurement in a series-compensated network

    SciTech Connect

    Lambert, J.; McNabb, D. (Hydro-Quebec, Montreal, Quebec (Canada)); Phadke, A.G. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))

    1994-01-01

    This paper describes the feasibility studies concerning an accurate voltage phasor measurement in series-compensated network undergoing large disturbances. The principal modes of distortions in such a network are described. Some of these modes are changing with the fundamental frequency. The phasor evaluation is based on a new digital filter approach in which the fundamental frequency is estimated using a least-square algorithm. The need to have special potential (voltage) transformers is also discussed. This approach would be used in a shunt reactor switching scheme for an overall voltage control of a transmission network.

  6. Compensating For GPS Ephemeris Error

    NASA Technical Reports Server (NTRS)

    Wu, Jiun-Tsong

    1992-01-01

    Method of computing position of user station receiving signals from Global Positioning System (GPS) of navigational satellites compensates for most of GPS ephemeris error. Present method enables user station to reduce error in its computed position substantially. User station must have access to two or more reference stations at precisely known positions several hundred kilometers apart and must be in neighborhood of reference stations. Based on fact that when GPS data used to compute baseline between reference station and user station, vector error in computed baseline is proportional ephemeris error and length of baseline.

  7. Huygens lens for angle compensation

    NASA Astrophysics Data System (ADS)

    Lévesque, Quentin; Bouchon, Patrick; Pardo, Fabrice; Pelouard, Jean-Luc; Haïdar, Riad

    2014-03-01

    Plasmonic lenses are based on complex combinations of nanoscale high aspect ratio slits. We show that their design can be greatly simplified, keeping similar performance while releasing technological constraints. The simplified system, called Huygens lens, consists in a central aperture surrounded by several identical single mode slits in a thin gold layer that does not rely anymore on surface plasmons. The focusing behaviour with respect to the position and number of slits is investigated, and we demonstrate the interest of this design to get compact array of lenses which are able to compensate the angle of incidence of the incoming wave.

  8. Charge amplifier with bias compensation

    SciTech Connect

    Johnson, Gary W. (Livermore, CA)

    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.

  9. A compensated vector control scheme of a synchronous reluctance motor including saturation and iron losses

    Microsoft Academic Search

    L. Xu; J. Yao

    1992-01-01

    A compensated vector control algorithm for a synchronous reluctance motor (SRM) including saturation and iron losses is presented. It is shown that the current components that directly govern the torque production have been very well regulated by the proposed control scheme. The computer simulation and experimental results indicate a substantial improvement of torque performance for the vector-controlled SRM

  10. Applying a compensated pulsed alternator to a flashlamp load for Nova. II

    Microsoft Academic Search

    W. L. Bird; D. J. T. Mayhall; W. F. Weldon; H. G. Rylander; H. H. Woodson

    1979-01-01

    The compensated pulsed alternator (compulsator) has been proposed as a possible alternative to capacitor banks for driving xenon flashlamps for pumping neodymium glass laser amplifiers for Nova. An algorithm for sizing rotor diameter and angular velocity as a function of flashlamp impedance, peak current, and delivered energy is described. It is shown that the armature inductance variation is a major

  11. A Novel Watermarking Scheme with Compensation in Bit-Stream Domain for H.264/AVC

    E-print Network

    Po, Lai-Man

    A Novel Watermarking Scheme with Compensation in Bit- Stream Domain for H.264/AVC Liwei Zhang1 SAR, China ABSTRACT Currently, most of the watermarking algorithms for H.264/AVC video coding standard the computational burden to decode the video, embed the watermark, and then re-encode it. Obviously

  12. 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.

  13. Motion-Compensating Real-Time Format Converter for Video on Multimedia Displays

    Microsoft Academic Search

    Matthias Braun; Martin Hahn; Jens-rainer Ohm; Maati Talmi

    1997-01-01

    This paper introduces a high-quality, low-cost video converter, for the conversion of interlaced TV signals into progressive display formats of the same or higher frame repetition rate. This conversion is performed by motion compensated filtering which is preceeded by motion esti- mation. The applied motion estimation algorithm operates on blocks sized 4 x 4 pixels. For each of these blocks,

  14. Refractive Index Compensation in Over-Determined Interferometric Systems

    PubMed Central

    Lazar, Josef; Holá, Miroslava; ?íp, Ond?ej; ?ížek, Martin; Hrabina, Jan; Buchta, Zden?k

    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

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

    PubMed

    Lazar, Josef; Holá, Miroslava; ?íp, Ond?ej; ?ížek, Martin; Hrabina, Jan; Buchta, Zden?k

    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

  16. 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.

  17. Efficient Motion Compensation Algorithm Based on Second-Order Prediction

    Microsoft Academic Search

    Seung Hwan Kim; Chang-su Kim; Sang Uk Lee

    2000-01-01

    Several techniques based on the multiple reference frame scheme have been proposed to improve the motion prediction gain. Though these techniques yield higher prediction gain than the single reference frame scheme, they require tremendous computational complexity during the motion search procedure. Besides, blocking artifacts may be visible along the block boundaries, since each macroblock is predicted independently of its neighbors.

  18. A temperature compensated 1 GHz STW oscillator

    Microsoft Academic Search

    M. A. Taslakov; I. D. Avramov

    1991-01-01

    An improved temperature compensation technique, applied to a 1-GHz surface transverse wave (STW) oscillator using 36° rotated Y-cut quartz, is described. The parabolic temperature dependence is roughly compensated for by an analog circuit. A fine compensation is performed by simple digital circuitry keeping the total instability within ±1.4 p.p.m. over the temperature range of (-45. . .+75)°C. The key for

  19. Multipurpose Active\\/Passive Motion Compensation System

    Microsoft Academic Search

    R. A. Sullivan; M. Davenport; R. Clements

    1984-01-01

    A microprocessor-controlled active\\/passive motion compensation system has been developed for deploying a variety of geotechnical in-situ testing devices with mobile drilling rigs from low-cost service vessels. The light-weight rotary heave compensator incorporates a hydraulic motor as the compensator actuator and a servo-controlled closed loop pump to reduce the air storage and power requirements. Unique features of the system are the

  20. Statistical Algorithm for Nonuniformity Correction in Focal-Plane Arrays

    Microsoft Academic Search

    Majeed M. Hayat; Sergio N. Torres; Ernest Armstrong; Stephen C. Cain; Brian Yasuda

    1999-01-01

    A statistical algorithm has been developed to compensate for the fixed-pattern noise associated with spatial nonuniformity and temporal drift in the response of focal-plane array infrared imaging systems. The algorithm uses initial scene data to generate initial estimates of the gain, the offset, and the variance of the additive electronic noise of each detector element. The algorithm then updates these

  1. 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.

  2. 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.

  3. Log amplifier with pole-zero compensation

    DOEpatents

    Brookshier, William (Downers Grove, IL)

    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.

  4. An algorithmic model of heading perception

    Microsoft Academic Search

    Mitsuhiko Hanada

    2005-01-01

    On the basis of Hanada and Ejima’s (2000) model, an algorithmic model was presented to explain psychophysical data of van den Berg and Beintema (2000) that are inconsistent with vector-subtractive compensation for the rotational flow. The earlier model was modified in order not to use vector-subtractive compensation for the rotational flow. The proposed model computes the center of flow first

  5. CAH DUAL COMPENSATION POLICY All Dual Compensation activities must be conducted in accordance with all university

    E-print Network

    Wu, Shin-Tson

    CAH DUAL COMPENSATION POLICY All Dual Compensation activities must be conducted in accordance with all university policies and state and federal regulations. For more information refer to: · UCF://regulations.ucf.edu/~regs/pdf/notices/3.0032AdditionalCompensationforUC FEmployees_finalJUN09_000.pdf ALL Dual Compensation

  6. A New Static Var Compensator for an Arc Furnace

    Microsoft Academic Search

    M. D. Cox; A. Mirbod

    1986-01-01

    This paper presents the design of an electronic compensator that can compensate the reactive current drawn by an arc furnace. Consisting of three independent single-phase pulse-width modulated (PWM) inverters, the proposed compensator responds quickly to any sudden load changes and compensates both the fundamental displacement current and the harmonic distortion current drawn by the load. Unlike conventional static var compensators,

  7. Active handheld instrument for error compensation in microsurgery

    NASA Astrophysics Data System (ADS)

    Riviere, Cameron N.; Khosla, Pradeep K.

    1998-01-01

    Physiological hand tremor and other manual positioning errors limit precision in microsurgical procedures. Our research has involved development of adaptive algorithms and neural network methods for real-time compensation of such errors. This paper presents a novel design for an active hand-held microsurgical instrument to implement these algorithms, particularly during vitreoretinal microsurgery. The basic vitreoretinal instrument consists of a handle fitted with a narrow freedom inertial sensing to determine the 3D position of the instrument tip. The intraocular shaft is attached to the instrument handle via a miniature parallel manipulator with three degrees of freedom, controlled by three piezoelectric elements. The manipulator actuates the intraocular shaft in pitch, yaw, and axial extension, allowing the system to perform active compensation of errors in the position of the tip of the intraocular shaft. The paper includes the formulation of the inverse kinematics of the instrument in a manner suitable for on-line computation. A discussion of practical design considerations and the methods and results of preliminary experiments are also presented.

  8. 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.

  9. Ground layer sensing and compensation Andrei Tokovinin

    E-print Network

    Tokovinin, Andrei A.

    is compensated. Low-altitude Rayleigh laser beacons (RLGSs) are a natural choice for Ground-Layer Adaptive Optics wavelengths. Keywords: Adaptive optics 1. INTRODUCTION It is an attractive idea to compensate only near-ground turbulence with adaptive optics.1­3 The ground layer usually produces most of the image degradation

  10. Steering compensation for high-performance motorcycles

    Microsoft Academic Search

    Simos Evangelou; David J. N. Limebeer; Robin S. Sharp; Malcolm C. Smith

    2004-01-01

    This paper introduces the idea of using a mechanical steering compensator to influence the dynamic behaviour of a high-performance motorcycle. The compensator is seen as a possible replacement for a conventional steering damper, and comprises a network of a spring, a damper and a less familiar component called the inerter. The inerter was recently introduced to allow the synthesis of

  11. Pure Price Effects of Nonwage Compensation

    Microsoft Academic Search

    Jeffrey S. Zax

    1985-01-01

    This paper discusses the pure static price effects which are engendered by tax preferences for nonwage compensation. Section II demonstrates that, because of these price effects, optimal consumption bundles will contain larger quantities of the goods included in nonwage compensation, and smaller quantities of other goods, than they would in the absence of tax preferences. In the presence of preferences,

  12. Compensation Basics For Managers and Supervisors

    E-print Network

    Weaver, Harold A. "Hal"

    ;4 Truths About Compensation Truth #2: The best employees are not attracted, motivated and retained solely About Compensation Truth # 4: An employee's knowledge of base pay correlates highly with pay satisfaction which is highly associated with job satisfaction. (Source: Knowledge of Pay Study (2000) conducted

  13. Dynamic heave compensation using robust estimation techniques

    Microsoft Academic Search

    Ferial El-Hawary; G. A. N. Mbamalu

    1996-01-01

    Compensating for underwater motion effects (heave component) arises in a number of activities. Earlier treatments relied on frequency response methods to model the phenomenon and subsequently applied Kaiman filtering for the compensation task. The success of the least squares estimation procedures depends on assuming that the estimation errors resulting from fitting a model to a set of data follow a

  14. Fast envelope detector with bias compensation

    Microsoft Academic Search

    S. M. Bryant

    1984-01-01

    In combination with an enveloped detector in a radar system, a bias compensation circuit consisting of a programmable read-only memory and a binary adder produce an unbiased envelope detection signal. The bias compensation circuit adds one to the output of the detector based upon whether the minimum of the I and Q (inphase and quadrature) signals is odd and the

  15. The Norwegian system of compensation to patients.

    PubMed

    Jørstad, Rolf Gunnar

    2002-01-01

    In Norway we have come to the conclusion that a traditional compensation law based on negligence is not the right "tool" for handling difficult questions as to whether or not a patient shall get compensation if required after medical treatment or other forms of contact with the medical profession. The compensation scheme established in 1988 involving the public sector of the Norwegian health care system has received almost 18000 claims since Jan 1 1988, and has paid out more than 1.2 billion NOK (137 million US$) in compensation during these years. At the same time, the number of compensation claims brought before the courts has decreased. After 13 years of a provisional scheme dealing with patient injury compensation based on no-fault rules, we find that compensation claims indeed can be handled without focus on blame and negligence, and that this ensures both that the patients get equitable compensation and that unnecessary legal procedures are avoided. The system also has had a favourable impact on interaction within the health care sector and upon relationships between health care personnel and patients. PMID:15795996

  16. Human Resource Management: Employee Compensation Guide 

    E-print Network

    Fogleman, Sarah L.; McCorkle, Dean

    2009-04-08

    Human Resource Management: Employee Compensation Guide Risk Management *Extension Agricultural Economist, Kansas State University Agricultural Experiment Station and Cooperative Extension Service; and Extension Program Specialist III.... ?Employee Compensation and Job Satisfaction on Dairy Farms in the Northeast.? April 1999. Cornell University, RB99-02. Kansas Department of Human Resources. Kansas Wage Survey, 1996 Edition. Rosenberg, Howard. ?Labor Management Decisions.? University...

  17. NUPlans Compensation Chart String Chart String Statuses

    E-print Network

    Shull, Kenneth R.

    NUPlans Compensation Chart String Statuses NUPlans Chart String Statuses FMS704 NUPlansChartStringStatusesV2 4/7/14 - rb © 2014 Northwestern University 1 of 2 This reference describes chart string status, the flow of compensation inputs, and whether you may need to correct a chart string (in bold). Chart String

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 21 CFR 868.2340 - Compensated thorpe tube flowmeter.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false Compensated thorpe tube flowmeter. 868.2340 Section 868...Devices § 868.2340 Compensated thorpe tube flowmeter. (a) Identification. A compensated thorpe tube flowmeter is a device intended for...

  4. 21 CFR 868.2340 - Compensated thorpe tube flowmeter.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 false Compensated thorpe tube flowmeter. 868.2340 Section 868...Devices § 868.2340 Compensated thorpe tube flowmeter. (a) Identification. A compensated thorpe tube flowmeter is a device intended for...

  5. 21 CFR 868.2340 - Compensated thorpe tube flowmeter.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false Compensated thorpe tube flowmeter. 868.2340 Section 868...Devices § 868.2340 Compensated thorpe tube flowmeter. (a) Identification. A compensated thorpe tube flowmeter is a device intended for...

  6. 21 CFR 868.2340 - Compensated thorpe tube flowmeter.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 false Compensated thorpe tube flowmeter. 868.2340 Section 868...Devices § 868.2340 Compensated thorpe tube flowmeter. (a) Identification. A compensated thorpe tube flowmeter is a device intended for...

  7. Position control of a servopneumatic system using fuzzy compensation

    E-print Network

    Sathyanarayana, Sreenivas

    2000-01-01

    The position control of a servopneumatic system in the presence of stick-slip type of friction is investigated. A cost effective, model-free fuzzy compensation scheme is proposed. The fuzzy compensation scheme compensates for the friction force...

  8. 21 CFR 868.2340 - Compensated thorpe tube flowmeter.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Compensated thorpe tube flowmeter. 868.2340 Section 868...Devices § 868.2340 Compensated thorpe tube flowmeter. (a) Identification. A compensated thorpe tube flowmeter is a device intended for...

  9. 28 CFR 301.301 - Compensable and noncompensable injuries.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Compensable and noncompensable injuries. 301.301 Section 301.301 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death §...

  10. 28 CFR 301.318 - Civilian compensation laws distinguished.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Civilian compensation laws distinguished. 301.318 Section 301.318 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death §...

  11. 28 CFR 301.316 - Subsequent incarceration of compensation recipient.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...incarceration of compensation recipient. 301.316 Section 301.316 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death §...

  12. 28 CFR 301.301 - Compensable and noncompensable injuries.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Compensable and noncompensable injuries. 301.301 Section 301.301 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death §...

  13. 28 CFR 301.318 - Civilian compensation laws distinguished.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Civilian compensation laws distinguished. 301.318 Section 301.318 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death §...

  14. 28 CFR 301.316 - Subsequent incarceration of compensation recipient.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...incarceration of compensation recipient. 301.316 Section 301.316 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE INMATE ACCIDENT COMPENSATION Compensation for Work-Related Physical Impairment or Death §...

  15. EHW Approach to Temperature Compensation of Electronics

    NASA Technical Reports Server (NTRS)

    Stoica, Adrian

    2004-01-01

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

  16. Atmospheric dust

    NSDL National Science Digital Library

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

    2003-01-01

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

  17. OFFICE OF RISK MANAGEMENT WORKER'S COMPENSATION POLICIES AND RESPONSIBILITIES

    E-print Network

    Berdichevsky, Victor

    physician, you must submit the provider's complete name, address, fax and phone numbers to the Office condition in order to be compensable under worker's compensation. PRESCRIPTION REIMBURSEMENT Prescriptions

  18. Pluto's atmosphere

    SciTech Connect

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

    1989-01-01

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

  19. Error Compensation for Area Digital Sun Sensor

    PubMed Central

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

    2012-01-01

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

  20. Mechanisms of X Chromosome Dosage Compensation

    PubMed Central

    Ercan, Sevinç

    2015-01-01

    In many animals, males have one X and females have two X chromosomes. The difference in X chromosome dosage between the two sexes is compensated by mechanisms that regulate X chromosome transcription. Recent advances in genomic techniques have provided new insights into the molecular mechanisms of X chromosome dosage compensation. In this review, I summarize our current understanding of dosage imbalance in general, and then review the molecular mechanisms of X chromosome dosage compensation with an emphasis on the parallels and differences between the three well-studied model systems, M. musculus, D. melanogaster and C. elegans. PMID:25628761

  1. Compensating For Doppler Shift In Laser Instrumentation

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.

    1990-01-01

    Electronic tuning system continually adjusts frequency of tunable diode laser to compensate for Doppler shift caused by motion of transmitter or receiver containing laser. Doppler-shift-compensating system intended primarily for use in transmitter or receiver of laser remote-sensing or communication system to keep frequency of received signal within frequency range of narrow-band-pass filter. By use of narrow-band filter (instead of wide-band filter required in absence of Doppler compensation), signal-to-noise ratio of laser system increased. Thus, less-powerful transmitter usable.

  2. Servomechanism compensating parameters solved by digital computer

    E-print Network

    Scott, Eldon Duane

    1957-01-01

    (s) - Transfer functIon of the lead network B(s) - Transfer funct1on of the lag network G(s) - Transfer function of the original servo The transfer function of the open-loop compensated servo- mechanism is Gc( s) = kA( s) ~ B( s) ~ G( s) ec( s) E( s) (5...) and the frequency response Is Gc( Jm) = kA( Jm) ~ B( Jm) ~ G( Jm) . The frequency response of the compensated closed-loop servomechanism is Gc ( J&) Gc( JM) 1+G (Jm) where E( s) = eI(s) - eo(s) (8) The design specifications for the compensated system may...

  3. Compensation of transmission losses for true-amplitude reverse time migration

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  4. Pluto's atmosphere

    Microsoft Academic Search

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

    1989-01-01

    Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates

  5. The Atmosphere.

    ERIC Educational Resources Information Center

    Ingersoll, Andrew P.

    1983-01-01

    The composition and dynamics of the earth's atmosphere are discussed, considering the atmosphere's role in distributing the energy of solar radiation received by the earth. Models of this activity which help to explain climates of the past and predict those of the future are also considered. (JN)

  6. A COGNITIVE COMPENSATION MECHANSIM FOR DEFORMABLE ANTENNAS 

    E-print Network

    Long, Stephen A.

    2010-07-14

    This thesis presents the design, theory, and measurement of a linearly polarized microstrip patch antenna with a novel substrate-integrated mechanism that can compensate the detuning effects from a physical deformation. Specifically, this antenna...

  7. Temperature compensated two-mode fiber interferometer 

    E-print Network

    Doma, Jagdish Ramchandra

    1993-01-01

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

  8. 12 CFR 620.31 - Compensation committees.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...TO SHAREHOLDERS Bank and Association Audit and Compensation Committees § 620.31...the potential for future losses or undue risks to the institution; (3) Senior officer...than senior officers, pose no imprudent risks to the institution. (c)...

  9. 48 CFR 836.577 - Workers' compensation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 false Workers' compensation. 836...CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...solicitations and contracts for construction that are expected to exceed...micro-purchase threshold for...

  10. 48 CFR 836.577 - Workers' compensation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 2014-10-01 false Workers' compensation. 836...CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...solicitations and contracts for construction that are expected to exceed...micro-purchase threshold for...

  11. 48 CFR 836.577 - Workers' compensation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 false Workers' compensation. 836...CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...solicitations and contracts for construction that are expected to exceed...micro-purchase threshold for...

  12. 48 CFR 836.577 - Workers' compensation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 2013-10-01 false Workers' compensation. 836...CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...solicitations and contracts for construction that are expected to exceed...micro-purchase threshold for...

  13. 48 CFR 836.577 - Workers' compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2012-10-01 false Workers' compensation. 836...CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...solicitations and contracts for construction that are expected to exceed...micro-purchase threshold for...

  14. 28 CFR 345.54 - Overtime compensation.

    Code of Federal Regulations, 2011 CFR

    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...

  15. 28 CFR 345.54 - Overtime compensation.

    Code of Federal Regulations, 2010 CFR

    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...

  16. Temperature compensation of light-emitting diodes

    NASA Technical Reports Server (NTRS)

    Deboo, G. J.; Burrous, C. N.

    1972-01-01

    Circuit which includes a thermistor-resistor combination to compensate for temperature fluctuations by supplying input voltage to light-emitting diode, maintains constant light output. Similar circuits can be used for temperature-induced variations in photodiode applications.

  17. 22 CFR 96.34 - Compensation.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Standards for Convention Accreditation and Approval Financial and Risk Management § 96.34 Compensation. (a...discloses to the accrediting entity any corporate or financial arrangements and any family relationships with...

  18. Comparing two approaches to compensable flow composition

    E-print Network

    Bruni, Roberto

    a new language but at comparing two main proposals, namely compensating CSP (cCSP) [7] and Sagas cal- culi [5]. Apart from stylistic differences (e.g., the trace semantics of cCSP and the big step SOS

  19. 7 CFR 930.61 - Handler compensation.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

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

  20. 7 CFR 930.61 - Handler compensation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

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

  1. Compensating for estimation smoothing in kriging

    USGS Publications Warehouse

    Olea, R.A.; Pawlowsky, Vera

    1996-01-01

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

  2. The effect of the light round-trip time on the performance of an adaptive optics turbulence compensation system

    Microsoft Academic Search

    P. Stroud

    1992-01-01

    The propagation of a laser beam through atmospheric turbulence can, under many circumstances, be compensated to near diffraction limited levels, by use of an adaptive optics system. In the ideal case, a beacon light source is generated at the aimpoint. This light traverses through the turbulent path back to the aperture. The distribution of phase perturbations in the aperture plane

  3. Temperature-Compensating Inactive Strain Gauge

    NASA Technical Reports Server (NTRS)

    Moore, Thomas C., Sr.

    1993-01-01

    Thermal contribution to output of active gauge canceled. High-temperature strain gauges include both active gauge wires sensing strains and inactive gauge wires providing compensation for thermal contributions to gauge readings. Inactive-gauge approach to temperature compensation applicable to commercially available resistance-type strain gauges operating at temperatures up to 700 degrees F and to developmental strain gauges operating at temperatures up to 2,000 degrees F.

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

    PubMed Central

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

    2011-01-01

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

  5. Wavelength Compensation in Fused Fiber Couplers.

    NASA Astrophysics Data System (ADS)

    Wang, Zhi G.

    The performance of fused fiber couplers is wavelength dependent. Wavelength spectral compensation is a technique to decrease the effect of the wavelength dependence, which is an essential task for many applications in fiber optic communication systems. Fiber devices such as wavelength -flattened couplers (WFCs) can be fabricated using wavelength spectral compensation methods. In this dissertation, wavelength spectral compensation techniques in fused biconical taper (FBT) couplers including both multimode and single-mode fiber couplers are studied in detail. In multimode fiber coupler operation, a novel theoretical model based on frustrated total internal reflection (FTIR) has been developed to effectively describe the power coupling and loss mechanism. Experimental results support the theoretical predictions. In single -mode fiber couplers, the conventional technique of fabricating WFCs is discussed. An alternative analytical model has been developed based upon coupled mode theory, which provides a relatively simple and mathematically sound explanation to the wavelength spectral compensation. Aiming to simplify WFC fabrication, a new way of constructing WFCs is proposed and demonstrated by connecting regular single-mode fiber couplers, some of which serve as wavelength spectral compensators. WFCs of various structures including 2 x 2, 1 x 3, 1 x 2 ^{N}, and 4 x 4 have been developed, and the experimental data agree with theoretical predictions of performance. Potential applications and future research directions in wavelength spectral compensation are also presented.

  6. Self-Compensation in Dilute Magnetic Semiconductors

    NASA Astrophysics Data System (ADS)

    Erwin, Steven C.

    2003-03-01

    Ferromagnetism in Mn-doped GaAs is generally believed to be mediated by holes created by the substitution of Mn for Ga. Over a wide range of Mn concentrations, measured hole concentrations are much smaller than expected from simple electron counting, suggesting a robust compensation mechanism. A similar effect is observed in Mn-doped Ge, where antisites cannot account for the compensation. We present a theory of self-compensation by interstitial Mn in Mn-doped ferromagnetic semiconductors. Using density-functional theory, we show that under the non-equilibrium conditions of growth, interstitial Mn is easily formed near the surface by a simple low-energy adsorption pathway. In GaAs, isolated interstitial Mn is an electron donor, each compensating two substitutional Mn acceptors. Within an impurity-band model, partial compensation actually promotes ferromagnetic order below the metal-insulator transition, with the highest Curie temperature occurring for 0.5 holes per substitutional Mn. Finally, we show that the observed properties of another dilute ferromagnetic semiconductor, Co-doped TiO2 are, in a similar way, most naturally explained as arising from self-compensation of Co substitutionals by Co interstitials.

  7. Multipurpose active/passive motion compensation system

    SciTech Connect

    Sullivan, R.A.; Clements, R.E.; Davenport, M.R.

    1984-05-01

    A microprocessor-controlled active/passive motion compensation system has been developed for deploying a variety of geotechnical in-situ testing devices with mobile drilling rigs from low-cost service vessels. The light-weight rotary heave compensator incorporates a hydraulic motor as the compensator actuator and a servo-controlled closed loop pump to reduce the air storage and power requirements. Unique features of the system are the use of inertial sensors to measure three components of boat motion, the ability to run the system in active/passive or passive modes, and the ability to automatically lower the drillstring at a constant velocity while maintaining motion compensation. Quantitative measurements made during sea trials offshore California yielded motion compensation accuracy approaching 98 percent which is much better than the compensation achieved with passive systems. Results are presented from offshore in-situ testing with a cone penetrometer, a vane shear device, and a suspension PS logger. The system can also be used for other offshore applications.

  8. Electronic noise compensation in iterative x-ray CT reconstruction

    NASA Astrophysics Data System (ADS)

    Xu, Jingyan; Tsui, Benjamin M. W.

    2008-03-01

    Electronic noise compensation can be important for low-dose x-ray CT applications where severe photon starvation occurs. For clinical x-ray CT systems utilizing energy-integrating detectors, it has been shown that the detected x-ray intensity is compound Poisson distributed, instead of the Poisson distribution that is often studied in the literature. We model the electronic noise contaminated signal Z as the sum of a compound Poisson distributed random variable (r.v.) Y and a Gaussian distributed electronic noise N with known mean and variance. We formulate the iterative x-ray CT reconstruction problem with electronic noise compensation as a maximum-likelihood reconstruction problem. However the likelihood function of Z is not analytically trackable; instead of working with it directly, we formulate the problem in the expectation-maximization (EM) framework, and iteratively maximize the conditional expectation of the complete log-likelihood of Y. We further demonstrate that the conditional expectation of the surrogate function of the complete log-likelihood is a legitimate surrogate for the incomplete surrogate. Under certain linearity conditions on the surrogate function, a reconstruction algorithm with electronic noise compensation can be obtained by some modification of one previously derived without electronic noise considerations; the change incurred is simply replacing the unavailable, uncontaminated measurement Y by its conditional expectation E(Y|Z). The calculation of E(Y|Z) depends on the model of Y, N, and Z. We propose two methods for calculating this conditional expectation when Y follows a special compound Poisson distribution - the exponential dispersion model (ED). Our methods can be regarded as an extension of similar approaches using the Poisson model to the compound Poisson model.

  9. Compensation for non-uniform attenuation in SPECT brain imaging

    SciTech Connect

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

    1994-05-01

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

  10. The research of moving object detection based on background difference compensation

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  11. Digital compensation of chromatic dispersion in 112-Gbit/s PDM-QPSK system

    NASA Astrophysics Data System (ADS)

    Xu, Tianhua; Jacobsen, Gunnar; Popov, Sergei; Li, Jie; Wang, Ke; Friberg, Ari T.

    2009-11-01

    High bit rates optical communication systems pose the challenge of their tolerance to linear and nonlinear fiber impairments. Coherent optical receivers using digital signal processing techniques can mitigate the fiber impairments in the optical transmission system, including the chromatic dispersion equalization with digital filters. In this paper, an adaptive finite impulse response filter employing normalized least mean square algorithm is developed for compensating the chromatic dispersion in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying coherent communication system, which is established in the VPI simulation platform. The principle of the adaptive normalized least mean square algorithm for signal equalization is analyzed theoretically, and at the meanwhile, the taps number and the tap weights in the adaptive finite impulse response filter for compensating a certain fiber chromatic dispersion are also investigated by numerical simulation. The chromatic dispersion compensation performance of the adaptive filter is analyzed by evaluating the behavior of the bit-error-rate versus the optical signal-to-noise ratio, and the compensation results are also compared with other present digital filters.

  12. Complex amplitude correlation for compensation of large in-plane motion in digital speckle pattern interferometry

    SciTech Connect

    Svanbro, Angelica; Sjoedahl, Mikael

    2006-12-01

    The use of complex amplitude correlation to compensate for large in-plane motion in digital speckle pattern interferometry is investigated. The result is compared with experiments where digital speckle photography (DSP) is used for compensation. An advantage of using complex amplitude correlation instead of intensity correlation (as in DSP) is that the phase change describing the deformation is retrieved directly from the correlation peak, and there is no need to compensate for the large movement and then use the interferometric algorithms. A discovered drawback of this method is that the correlation values drop quickly if a phase gradient larger than {pi} is present in the subimages used for cross correlation. This means that, for the complex amplitude correlation to be used, the size of the subimages must be well chosen or a third parameter in the cross-correlation algorithm that compensates for the phase variation is needed.Correlation values and wrapped phase maps from the two techniques (intensity and complex amplitude correlation) are presented.

  13. Enhancement of Corneal Visibility in Optical Coherence Tomography Images Using Corneal Adaptive Compensation

    PubMed Central

    Girard, Michaël J. A.; Ang, Marcus; Chung, Cheuk Wang; Farook, Mohamed; Strouthidis, Nick; Mehta, Jod S.; Mari, Jean Martial

    2015-01-01

    Purpose: To improve the contrast of optical coherence tomography (OCT) images of the cornea (post processing). Methods: We have recently developed standard compensation (SC) algorithms to remove light attenuation artifacts. A more recent approach, namely adaptive compensation (AC), further limited noise overamplification within deep tissue regions. AC was shown to work efficiently when all A-scan signals were fully attenuated at high depth. But in many imaging applications (e.g., OCT imaging of the cornea), such an assumption is not satisfied, which can result in strong noise overamplification. A corneal adaptive compensation (CAC) algorithm was therefore developed to overcome such limitation. CAC benefited from local A-scan processing (rather than global as in AC) and its performance was compared with that of SC and AC using Fourier-domain OCT images of four human corneas. Results: CAC provided considerably superior image contrast improvement than SC or AC did, with excellent visibility of the corneal stroma, low noise overamplification, homogeneous signal amplification, and high contrast. Specifically, CAC provided mean interlayer contrasts (a measure of high stromal visibility and low noise) greater than 0.97, while SC and AC provided lower values ranging from 0.38 to 1.00. Conclusion: CAC provided considerable improvement compared with SC and AC by eliminating noise overamplification, while maintaining all benefits of compensation, thus making the corneal endothelium and corneal thickness easily identifiable. Translational Relevance: CAC may find wide applicability in clinical practice and could contribute to improved morphometric and biomechanical understanding of the cornea.

  14. Exoplanetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Madhusudhan, N.; Knutson, H.; Fortney, J. J.; Barman, T.

    The study of exoplanetary atmospheres is one of the most exciting and dynamic frontiers in astronomy. Over the past two decades ongoing surveys have revealed an astonishing diversity in the planetary masses, radii, temperatures, orbital parameters, and host stellar properties of exoplanetary systems. We are now moving into an era where we can begin to address fundamental questions concerning the diversity of exoplanetary compositions, atmospheric and interior processes, and formation histories, just as have been pursued for solar system planets over the past century. Exoplanetary atmospheres provide a direct means to address these questions via their observable spectral signatures. In the last decade, and particularly in the last five years, tremendous progress has been made in detecting atmospheric signatures of exoplanets through photometric and spectroscopic methods using a variety of spaceborne and/or groundbased observational facilities. These observations are beginning to provide important constraints on a wide gamut of atmospheric properties, including pressure-temperature profiles, chemical compositions, energy circulation, presence of clouds, and nonequilibrium processes. The latest studies are also beginning to connect the inferred chemical compositions to exoplanetary formation conditions. In the present chapter, we review the most recent developments in the area of exoplanetary atmospheres. Our review covers advances in both observations and theory of exoplanetary atmospheres, and spans a broad range of exoplanet types (gas giants, ice giants, and super-Earths) and detection methods (transiting planets, direct imaging, and radial velocity). A number of upcoming planet-finding surveys will focus on detecting exoplanets orbiting nearby bright stars, which are the best targets for detailed atmospheric characterization. We close with a discussion of the bright prospects for future studies of exoplanetary atmospheres.

  15. STATCOM for compensation of large electric arc furnace installations

    Microsoft Academic Search

    C. Schauder

    1999-01-01

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

  16. Friction Problems in Servomechanisms: Modeling and Compensation Techniques

    E-print Network

    Gravdahl, Jan Tommy

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

  17. 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.

  18. Atmospheric Mass

    NSDL National Science Digital Library

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

  19. Planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Leovy, C.

    1987-03-01

    Observations and theoretical models of planetary atmospheres published during the period 1983-1986 are reviewed, including Vega and Voyager data and results from ground-based remote sensing. Consideration is given to water-vapor and sulfur-compound distributions, electrical phenomena, and dynamics in the Venus atmosphere; dust storms, water cycles, and water and ice erosion on Mars; the compositions, temperature profiles, and dynamics of the Jovian and Saturnian atmospheres; chemical processes and zonal winds on Titan; and the radiation budgets and chemical compositions of the outer planets.

  20. Quantitative assessment of tumor angiogenesis using real-time motion-compensated contrast-enhanced ultrasound imaging

    PubMed Central

    Pysz, Marybeth A.; Guracar, Ismayil; Foygel, Kira; Tian, Lu; Willmann, Jürgen K.

    2015-01-01

    Purpose To develop and test a real-time motion compensation algorithm for contrast-enhanced ultrasound imaging of tumor angiogenesis on a clinical ultrasound system. Materials and methods The Administrative Institutional Panel on Laboratory Animal Care approved all experiments. A new motion correction algorithm measuring the sum of absolute differences in pixel displacements within a designated tracking box was implemented in a clinical ultrasound machine. In vivo angiogenesis measurements (expressed as percent contrast area) with and without motion compensated maximum intensity persistence (MIP) ultrasound imaging were analyzed in human colon cancer xenografts (n = 64) in mice. Differences in MIP ultrasound imaging signal with and without motion compensation were compared and correlated with displacements in x- and y-directions. The algorithm was tested in an additional twelve colon cancer xenograft-bearing mice with (n = 6) and without (n = 6) anti-vascular therapy (ASA-404). In vivo MIP percent contrast area measurements were quantitatively correlated with ex vivo microvessel density (MVD) analysis. Results MIP percent contrast area was significantly different (P < 0.001) with and without motion compensation. Differences in percent contrast area correlated significantly (P < 0.001) with x- and y-displacements. MIP percent contrast area measurements were more reproducible with motion compensation (ICC = 0.69) than without (ICC = 0.51) on two consecutive ultrasound scans. Following anti-vascular therapy, motion-compensated MIP percent contrast area significantly (P = 0.03) decreased by 39.4 ± 14.6 % compared to non-treated mice and correlated well with ex vivo MVD analysis (Rho = 0.70; P = 0.05). Conclusion Real-time motion-compensated MIP ultrasound imaging allows reliable and accurate quantification and monitoring of angiogenesis in tumors exposed to breathing-induced motion artifacts. PMID:22535383

  1. Photoconductor surface modeling for defect compensation based on printed images

    NASA Astrophysics Data System (ADS)

    Eid, Ahmed H.; Cooper, Brian E.

    2015-01-01

    Manufacturing imperfections of photoconductor (PC) drums in electrophotographic (EP) printers cause low- frequency artifacts that could produce objectionable non-uniformities in the final printouts. In this paper, we propose a technique to detect and quantify PC artifacts. Furthermore, we spatially model the PC drum surface for dynamic compensation of drum artifacts. After scanning printed pages of flat field areas, we apply a wavelet- based filtering technique to the scanned images to isolate the PC-related artifacts from other printing artifacts, based on the frequency, range, and direction of the PC defects. Prior knowledge of the PC circumference determines the printed area at each revolution of the drum for separate analysis. Applied to the filtered images, the expectation maximization (EM) algorithm models the PC defects as a mixture of Gaussians. We use the estimated parameters of the Gaussians to measure the severity of the defect. In addition, a 2-D polynomial fitting approach characterizes the spatial artifacts of the drum, by analyzing multiple revolutions of printed output. The experimental results show a high correlation of the modeled artifacts from different revolutions of a drum. This allows for generating a defect-compensating profile of the defective drum.

  2. Application of MODTRAN to Planetary Atmospheres

    Microsoft Academic Search

    L. Bernstein; R. Sundberg; A. Singer-Berk

    2007-01-01

    MODTRAN(TM) is a widely used radiative-transfer (RT) code for computing the transmission, emission and scattering in the Earth's atmosphere. However, the RT algorithms used in MODTRAN(TM) are generally applicable to any layered atmosphere, and, in principle, can be applied to any planetary atmosphere. The primary required modification required for this application is the development of the appropriate spectral properties data

  3. Torque Ripple Minimization with Instantaneous Current Feedback Compensation for Switched Reluctance Motors

    NASA Astrophysics Data System (ADS)

    Rishab, Paudel; Ishikawa, Hiroki; Naitoh, Haruo

    This paper presents a novel strategy for torque ripple minimization with instantaneous current feedback compensation for switched reluctance motors (SRMs). The authors have already proposed suitable reference current profiles and a control algorithm to obtain an instantaneously flat torque of an SRM and confirmed the effectiveness of the algorithm by performing experiment in the low-speed range. In the high-speed range, however, the winding current cannot track the reference current owing to the lack of necessary voltage. In this study, mathematical analyses on the inability to trace the current profiles are performed. A new current control with compensation of the current profiles with instantaneous feedback is proposed. The validity of the proposed control is demonstrated by the experimental results.

  4. Earth's Atmosphere

    NSDL National Science Digital Library

    2012-08-03

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

  5. Exoplanet Atmospheres

    E-print Network

    Seager, Sara

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

  6. Exoplanetary Atmospheres

    E-print Network

    Madhusudhan, Nikku; Fortney, Jonathan; Barman, Travis

    2014-01-01

    The study of exoplanetary atmospheres is one of the most exciting and dynamic frontiers in astronomy. Over the past two decades ongoing surveys have revealed an astonishing diversity in the planetary masses, radii, temperatures, orbital parameters, and host stellar properties of exoplanetary systems. We are now moving into an era where we can begin to address fundamental questions concerning the diversity of exoplanetary compositions, atmospheric and interior processes, and formation histories, just as have been pursued for solar system planets over the past century. Exoplanetary atmospheres provide a direct means to address these questions via their observable spectral signatures. In the last decade, and particularly in the last five years, tremendous progress has been made in detecting atmospheric signatures of exoplanets through photometric and spectroscopic methods using a variety of space-borne and/or ground-based observational facilities. These observations are beginning to provide important constraints...

  7. Atmospheric pollution

    SciTech Connect

    Pickett, E.E.

    1987-01-01

    Atmospheric pollution (AP), its causes, and measures to prevent or reduce it are examined in reviews and reports presented at a workshop held in Damascus, Syria in August 1985. Topics discussed include AP and planning studies, emission sources, pollutant formation and transformation, AP effects on man and vegetation, AP control, atmospheric dispersion mechanisms and modeling, sampling and analysis techniques, air-quality monitoring, and applications. Diagrams, graphs, and tables of numerical data are provided.

  8. Atmospheric Deposition

    Microsoft Academic Search

    Kathleen C. Weathers; Alexandra G. Ponette-González

    \\u000a Atmospheric deposition plays a key role in the biogeochemistry of temperate, tropical, and boreal forests. Many essential\\u000a macro- and micronutrients as well as pollutants are delivered from the atmosphere to forest ecosystems: (1) dissolved in rain\\u000a and snow (wet deposition); (2) directly as particles and gases (dry deposition); and (3) dissolved in cloud droplets (cloud,\\u000a occult, or fog deposition, hereafter

  9. Estimation and Compensation of aberrations in Spatial Light Modulators

    NASA Astrophysics Data System (ADS)

    Arias, Augusto; Castaneda, Roman

    2011-01-01

    The spatial light modulator (SLM) Holoeye LC-R720 is based on LCoS (Liquid Crystal on Silicon) technology. Due to the induced curvatures on the silicon plate by the production process, there are static aberrations in the wave-fronts modified by the SLM. In order to calculate the aberrated wave-front we used phase-shifting interferometry, an optimization algorithm for far field propagation, and the geometric characterization of the focal spot along the caustic. Zernike polynomials were used for expanding and comparing the wave-fronts. The aberration compensation was carried out by displaying the conjugated transmittance on the SLM. The complexity of the experimental setup and the requirements of the digital processing of each estimation method were comparatively analyzed.

  10. The digital implementation of control compensators: The coefficient wordlength issue

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  11. Atmospheric Dust

    NSDL National Science Digital Library

    Millions of tons of dust are lifted from deserts annually, suspended in the atmosphere, and released to fall on the oceans, but scientists are a long way from understanding the impact of atmospheric dust on the climate and weather systems of Earth or on marine organisms. This radio broadcast explains how the nitrogen, phosphorus and iron released from dust boosts the growth of phytoplankton, which also soak up carbon dioxide and release more gases into the atmosphere. Better monitoring and more sophisticated sensors are giving us a more accurate picture of the dust in the atmosphere; the broadcast reports on investigations of dust from ice cores and on computer simulations of the connections between dust and climate. But the unpredictable nature of dust events makes it extremely difficult to determine their impact on the natural systems of Earth. There are discussions with geographers, oceanographers, environmentalists and climate modelers about atmospheric dust, one of the least understood and most contradictory components of the atmosphere. The broadcast is 28 minutes in length.

  12. Comparison of four discrete-time repetitive control algorithms

    Microsoft Academic Search

    Carl Kempf; William Messner; Masayoshi Tomizuka; Roberto Horowitz

    1993-01-01

    Four different algorithms used for cancellation of periodic disturbances are presented and compared. For each method, the theoretical advantages and disadvantages, computational complexity, execution time, and method of implementation are discussed. Experimental data from the use of these algorithms in compensating for repetitive disturbances present in the tracking servo of a computer disk drive are presented

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  14. Aperture compensation technique for innovative design of ultra-broadband microstrip bandpass filter

    Microsoft Academic Search

    Lei Zhu; Huizheng Bu; Ke Wu

    2000-01-01

    Aperture compensation technique is proposed for the enhancement of coupling strength in the parallel-coupled microstrip line (PCML). Through applying a so-called “short-open calibration” procedure in our full-wave MoM algorithm, this PCML is characterized by an equivalent J-inverter network. A novel bandpass filter with a single resonator is designed through its equivalent circuit topology. Both predicted and measured results show its

  15. Blind I\\/Q imbalance compensation using independent component analysis in MIMO OFDM systems

    Microsoft Academic Search

    Jingbo Gao; Xu Zhu; Hai Lin; Asoke K. Nandi

    2009-01-01

    I\\/Q imbalance, which is one of the radio frequency (RF) circuit impairments in direct conversion transmitter and receiver, introduces severe performance degradation in wireless communication systems. In this paper, we propose a novel blind compensation algorithm for both frequency-dependent and frequency-independent I\\/Q imbalance based on independent component analysis (ICA) in multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM)

  16. In flight MTF monitoring and compensation for CCD camera on CBERS-02

    Microsoft Academic Search

    Xingfa Gu; Xiaoying Li; Xiangjun Min; Tao Yu; Jijuan Sun; Yong Zeng; Hua Xu; Ding Guo

    2005-01-01

    In this article, the approach of simulating ideal tarp scene was proposed to determine the MTF for CCD camera on CBERS-02.\\u000a The MTF acquired from this technique was compared to those from some common methods. MTFs achieved from different approaches\\u000a were employed to compensate the CCD images based on three restoration algorithms: the iterative method, the Wiener filter\\u000a and the

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

    Microsoft Academic Search

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

    1996-01-01

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

  18. A novel high power self-commutated static VAr compensator for load compensation

    Microsoft Academic Search

    Kishore Chatterjee; B. G. Fernandes; Gopal K. Dubey

    1997-01-01

    A novel high power self-commutated static VAr compensator for load compensation is proposed. The harmonics are eliminated by combining low frequency high power devices and high frequency low power devices. A modified control strategy is also proposed for applications involving high and faster rate of change in VAr demand. Detailed simulation studies for single phase and three phase topologies are

  19. Randomized Algorithms

    Microsoft Academic Search

    Rajeev Motwani; Prabhakax Raghavan

    1995-01-01

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

  20. TES Level 2 Algorithm Theoretical Basis Document JPL D-16474

    E-print Network

    Waliser, Duane E.

    (TES) LEVEL 2 ALGORITHM THEORETICAL BASIS DOCUMENT APPENDIX Reinhard Beer Jet Propulsion Laboratory Kevin W. Bowman Jet Propulsion Laboratory Patrick D. Brown Atmospheric and Environmental Research Inc. Shepard A. Clough Atmospheric and Environmental Research Inc. Annmarie Eldering Jet Propulsion Laboratory

  1. Risk compensation behaviours in construction workers' activities.

    PubMed

    Feng, Yingbin; Wu, Peng

    2015-01-01

    The purpose of this study was to test whether the construction workers have the tendency of engaging in risk compensation behaviours, and identify the demographic variables, which may influence the extent to which the construction workers may show risk compensation behaviours. Both quantitative (survey) and qualitative (interviews) approaches were used in this study. A questionnaire survey was conducted with all the construction workers on three building construction sites of a leading construction company in Australia. Semi-structured interviews were then conducted to validate the findings of the quantitative research. The findings indicate that workers tend to show risk compensation behaviours in the construction environment. The workers with more working experience, higher education, or having never been injured at work before have a higher tendency to show risk compensation in their activities than the others. The implication is that contractors need to assess the potential influence of workers' risk compensation behaviours when evaluating the effect of risk control measures. It is recommended that supervisors pay more attention to the behavioural changes of those workers who have more experience, higher education, and have never been injured before after the implementation of new safety control measures on construction site. PMID:24134314

  2. Rapid springback compensation for age forming based on quasi Newton method

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Iterative methods based on finite element simulation are effective approaches to design mold shape to compensate springback in sheet metal forming. However, convergence rate of iterative methods is difficult to improve greatly. To increase the springback compensate speed of designing age forming mold, process of calculating springback for a certain mold with finite element method is analyzed. Springback compensation is abstracted as finding a solution for a set of nonlinear functions and a springback compensation algorithm is presented on the basis of quasi Newton method. The accuracy of algorithm is verified by developing an ABAQUS secondary development program with MATLAB. Three rectangular integrated panels of dimensions 710 mm ×750 mm integrated panels with intersected ribs of 10 mm are selected to perform case studies. The algorithm is used to compute mold contours for the panels with cylinder, sphere and saddle contours respectively and it takes 57%, 22% and 33% iterations as compared to that of displacement adjustment (DA) method. At the end of iterations, maximum deviations on the three panels are 0.618 4 mm, 0.624 1 mm and 0.342 0 mm that are smaller than the deviations determined by DA method (0.740 8 mm, 0.740 8 mm and 0.713 7 mm respectively). In following experimental verification, mold contour for another integrated panel with 400 mm×380 mm size is designed by the algorithm. Then the panel is age formed in an autoclave and measured by a three dimensional digital measurement devise. Deviation between measuring results and the panel's design contour is less than 1 mm. Finally, the iterations with different mesh sizes (40 mm, 35 mm, 30 mm, 25 mm, 20 mm) in finite element models are compared and found no considerable difference. Another possible compensation method, Broyden-Fletcher-Shanmo method, is also presented based on the solving nonlinear functions idea. The Broyden-Fletcher-Shanmo method is employed to compute mold contour for the second panel. It only takes 50% iterations compared to that of DA. The proposed method can serve a faster mold contour compensation method for sheet metal forming.

  3. Phase extraction and unwrapping using rotational and direct compensators for digital hologram

    NASA Astrophysics Data System (ADS)

    Heshmat, Samia; Tomioka, Satoshi; Nishiyama, Shusuke

    2013-10-01

    The growing interest in the applications of digital holography interferometry has led to an increasing demand for reliable phase unwrapping techniques. In digital holography, the phase carries three-dimensional surface information about the object. However, phase mapping is ambiguous as the extracted phase is returned in a form that suffers from 2? phase jumps. Furthermore, the presence of noise in the measured data, in which many singular points (SP) are found, often makes general phase unwrapping algorithms fail to produce accurate unwrapped results. Therefore, it is necessary to use a powerful phase unwrapping method to recover the desired smooth phase surface. For this reason, we developed a phase unwrapping algorithm that is applicable to digital hologram maps. The developed algorithm solves the singularity problem caused by SPs as a result of compensating its effect by using rotational and direct compensators. We show a difference in performance between our developed phase unwrapping algorithm and other well known phase unwrapping methods for digital holographic data. In addition, the methods to extract phase information of the object from hologram maps are also investigated. Results show that the developed algorithm gives satisfactory unwrapped results with low computational time cost.

  4. Bimaterial Thermal Compensators for WGM Resonators

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    Bimaterial thermal compensators have been proposed as inexpensive means of preventing (to first order) or reducing temperature-related changes in the resonance frequencies of whispering-gallery-mode (WGM) optical resonators. A bimaterial compensator would apply, to a WGM resonator, a pressure that would slightly change the shape of the resonator and thereby change its resonance frequencies. Through suitable choice of the compensator dimensions and materials, it should be possible to make the temperature dependence of the pressure-induced frequency shift equal in magnitude and opposite in sign to the temperature dependence of the frequency shift of the uncompensated resonator so that, to first order, a change in temperature would cause zero net change in frequency.

  5. Passive Limitations for a Magnetic Gravity Compensator

    NASA Astrophysics Data System (ADS)

    Janssen, Jeroen L. G.; Paulides, Johannes J. H.; Lomonova, Elena A.

    The development of sophisticated advanced vibration isolation is important because even the minutest vibrations have disastrous effects on the performance of static and moving parts in high-precision machines. This paper concerns with the isolation of these vibrations for a large static body in an advanced micro-lithographic system, where a passive/active electromagnetic solution is presented. In these configurations passive permanent magnets (PM) provide the gravity compensation and active electromagnets the accurate positioning. This paper only considers the applicability of a passive magnetic solution for this high force gravity compensation application, or, more specifically, the influence of various PM array topologies on the force density. Further, fast-solving analytical models are presented and consequently are used to illustrate the feasibility of using passive permanent magnets for gravity compensation in this demanding high precision industrial application.

  6. Representing Range Compensators with Computational Geometry in TOPAS

    SciTech Connect

    Iandola, Forrest N.; /Illinois U., Urbana /SLAC

    2012-09-07

    In a proton therapy beamline, the range compensator modulates the beam energy, which subsequently controls the depth at which protons deposit energy. In this paper, we introduce two computational representations of range compensator. One of our compensator representations, which we refer to as a subtraction solid-based range compensator, precisely represents the compensator. Our other representation, the 3D hexagon-based range compensator, closely approximates the compensator geometry. We have implemented both of these compensator models in a proton therapy Monte Carlo simulation called TOPAS (Tool for Particle Simulation). In the future, we will present a detailed study of the accuracy and runtime performance trade-offs between our two range compensator representations.

  7. Application of MODTRAN ™ to ExtraTerrestrial Planetary Atmospheres

    Microsoft Academic Search

    Lawrence S. Bernstein; Alexander Berk; Robert L. Sundberg

    MODTRAN ™ (1) is a widely used radiative-transfer (RT) code for computing the transmission and emission of the Earth's atmosphere. However, the RT algorithms used in MODTRAN ™ are generally applicable to any layered atmosphere, and, in principle, can be applied to any planetary atmosphere. The primary modification required for this application is the development of the appropriate spectral properties

  8. Atmospheric correction over heterogeneous surfaces on ASTER visible data

    Microsoft Academic Search

    Tsutomu Takashima; Kazuhiko Masuda

    1998-01-01

    An atmospheric correction algorithm to include the effect of adjacent pixels on the emergent radiation from the top of the atmosphere is proposed. The surface is simulated by checkerboard type terrain composed of land or ocean pixels. The Look-Up-Table method is used for the atmospheric correction. To investigate the contribution of adjacent pixels, two additional parameters based on the diffuse

  9. Atmospheric correction for the satellite visible data over heterogeneous surfaces

    Microsoft Academic Search

    Tsutomu Takashima; Kazuhiko Masuda

    2000-01-01

    An atmospheric correction algorithm over the heterogeneous surface on the emergent radiation from the top of the atmosphere is proposed. The surface is simulated by checkerboard type terrain composed of land or ocean pixels. The look-up-table method is used for the atmospheric correction. To investigate the contribution of adjacent pixels, two additional parameters based on the diffuse transmission and reflection

  10. Gigabit Ethernet Asynchronous Clock Compensation FIFO

    NASA Technical Reports Server (NTRS)

    Duhachek, Jeff

    2012-01-01

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

  11. Skew quad compensation for SPEAR minibeta optics

    SciTech Connect

    Wille, K.

    1984-06-01

    With the new minibeta insertion for SPEAR the betatron coupling and the perturbations of beam optics caused by the solenoid field of the MARK III detector can't be compensated by the simple coils used so far. Therefore another scheme with four skew quads arranged in two families has been chosen. Even though this scheme doesn't compensate the effect of the solenoid on the beam completely, the residual emittance coupling is much less than 1% which should be sufficient under all running conditions. The major advantage of this concept is its simplicity.

  12. Atmospheric radiation

    SciTech Connect

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

    1991-01-01

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

  13. Accurate Die Design for Automotive Panel Stamping Considering the Compensation Related with Die Deflection and Blank Thinning

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Xu, Dongkai; Xia, Guodong; Li, Xifeng; Chen, Jieshi; Zhang, Jian; Yan, Wei; Li, Yue

    2011-08-01

    In order to improve assembly accuracy, automotive body panels have to be fabricated with higher dimensional and surface quality requirements, therefore the die faces should be designed more accurately to consider more relevant factors. In the presented study, we proposed algorithms to realize the following functions: through forming process simulation, the thinning distribution on the deformed blank was extracted as first kind of compensation; through die structural CAE analysis which automatically mapped the boundary contact forces onto the die surfaces from process simulation results, the die deflection was calculated as second kind of compensation. These two quantitative contributions were added together to compensate the die face. The proposed methodologies were programmed and integrated with LS-Dyna and HyperWorks, and also integrated with Autoform and CATIA linear CAE functionalities separately. In addition, a software toolkit to calculate the contacting ratio was also developed to evaluate the effectiveness of die face compensation. The second toolkit developed was verified by an automotive structural part forming die design, through die compensation and geometric optimization, the predicted contact ratio between the die face and formed blank was improved a lot, and the first toolkit was testified by a fender drawing die design. It shows that the die face compensation can be realized and integrated seamlessly between CAD model, process simulation model and die structural CAE model with the help of data I/O tools developed by the authors.

  14. Atmospheric Chemistry

    NSDL National Science Digital Library

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

  15. 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.

  16. Development of infrared interferometry for upper atmospheric emission studies.

    PubMed

    Baker, D; Steed, A; Stair, A T

    1981-05-15

    This paper is a review of the historical development of the Michelson interferometer into modern-day Fourier transform spectrometry (FTS) used for upper atmospheric emission studies in the near IR. For the period of the last decade, the focus of the review is upon USAF/USU interferometric instruments. Michelson invented the "cross beam" interferometer in 1880; however, the first interferogram was not reported until that of Wood in 1911. Fellgett deduced the multiplex advantage in 1949. By the early 1950s, both Jacqui-not and Rupert had pointed out the throughput advantage, and Fellgett and Strong had each obtained Fourier transforms of interferograms. In 1959, J. Connes and Gush obtained a spectrum of the nighttime IR airglow in 30 min using a Michelson interferometer. In 1962 Gush and Buijs flew an interferometer aboard a balloon to obtain spectra from the airglow. Mertz and M. Block developed a commercial Michelson interferometer in about 1959. L. Block of AFCRL flew a Michelson interferometer aboard a satellite in 1962. In 1965, Connes and Connes obtained high-resolution spectra of planets using cat's-eye retroreflectors coupled with an interferometrically controlled step and integrate method. NASA successfully flew an interferometer aboard a satellite in 1969, which led to including FTS experiments on the planetary probes. In 1965 Tukey and Cooley published their FFT computer program based upon the algorithm of Good. AFGL/USU applied the FFT algorithm to FTS that same year. Stair launched a rocketborne liquid-He cooled interferometer in 1976 which obtained spectra of earth limb emissions. Mertz in 1959 approached field-of-view widening of an interferometer using variable thickness glass compensator plates. Baker and his USU staff used the Connes-Bouchareine compensation method to develop a series of wide-angle Michelson interferometers (WAMIs) for airglow and auroral studies. In 1973, they created a cryogenic WAMI to obtain an IR airglow spectrum in only 10 sec. A rocketborne version was successfully flown to obtain airglow spectra in 1979. This instrument took a 2-cm(-1) interferogram in 1 sec., used a liquid-He cooled detector to cover the 2-8-microm range, and the NESR was 3 x 10(-13) W cm(-2) sr(-1)/cm(-1) at 5 microm. PMID:20332829

  17. Employing Conjoint Analysis in Making Compensation Decisions.

    ERIC Educational Resources Information Center

    Kienast, Philip; And Others

    1983-01-01

    Describes a method employing conjoint analysis that generates utility/cost ratios for various elements of the compensation package. Its superiority to simple preference surveys is examined. Results of a study of the use of this method in fringe benefit planning in a large financial institution are reported. (Author/JAC)

  18. Subreflectarrays for Reflector Surface Distortion Compensation

    Microsoft Academic Search

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

    2009-01-01

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

  19. Method for mask repair using defect compensation

    DOEpatents

    Sweeney, Donald W. (San Ramon, CA); Ray-Chaudhuri, Avijit K. (Livermore, CA)

    2001-01-01

    A method for repair of amplitude and/or phase defects in lithographic masks. The method involves modifying or altering a portion of the absorber pattern on the surface of the mask blank proximate to the mask defect to compensate for the local disturbance (amplitude or phase) of the optical field due to the defect.

  20. Hexagram converter for static VAR compensation

    Microsoft Academic Search

    Jun Wen; K. M. Smedley

    2008-01-01

    A new multilevel converter - Hexagram converter is proposed for static VAR compensation in high-voltage high- power applications. The new converter is composed of six three- phase two-level standard voltage source converter (VSC) modules interconnected through inductors. It has the advantages of modular structure leading to easy construction and maintenance, no voltage unbalance, low voltage stress, low dc energy storage,

  1. Space Charge Compensation in Laser Particle Accelerators

    E-print Network

    Brookhaven National Laboratory

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

  2. LEGAL ASPECTS OF RADIATION INJURIES AND COMPENSATION

    Microsoft Academic Search

    Herzel H. E. Plaine; H. H. E

    1963-01-01

    There are a half dozen background factors in considering legal liability ; for and compensability of radiation injuries for persons occupationally exposed ; to radiation. First, all persons, as well as those occupationally involved, are ; regularly exposed to radiation. Occupational exposure is but a small percentage ; of the overall from all sources. Second, existing medical knowledge can tell

  3. Friction Compensation and Robust Hybrid Control

    Microsoft Academic Search

    B. Bona; M. Indri

    1993-01-01

    In force\\/position control, possible uncertainties about the manipulator parameters and the presence of friction and striction on the contact surfaces compromise the correct decoupling of the two controls and can sometimes cause instability. A fixed friction compensation function is constructed in order to achieve stability when friction and striction are present. Robust control techniques are applied. Simulation results of the

  4. Motion Artifact Compensation in CT Detlef Zerfowski

    E-print Network

    Zerfowski, Detlef

    of the deformation of the scanned object. Several different methods have been proposed to reduce motion artifactsMotion Artifact Compensation in CT Detlef Zerfowski Institut f¨ur Algorithmen und Kognitive Systeme, motion artifacts, image preprocessing. 1. INTRODUCTION In computerized tomography, patient motions play

  5. Quality-Controlled Motion-Compensated Interpolation

    E-print Network

    Girod, Bernd

    results in spatial artifacts especially in video frames with high motion. In the case of lowQuality-Controlled Motion-Compensated Interpolation Mina Makar, Derek Pang, Yao-Chung Lin and Bernd and power-sensitive applications. One way to reduce encoding complexity is to drop frames at the encoder

  6. The compensated pulsed alternator - Preliminary test results

    Microsoft Academic Search

    W. L. Bird; W. F. Weldon; H. G. Rylander; H. H. Woodson; B. M. Carder; B. T. Merritt; W. F. Gagnon

    1979-01-01

    An engineering prototype compensated pulsed alternator (Compulsator) has been designed and fabricated. The prototype compulsator is designed to drive a load consisting of sixteen parallel xenon flashlamps, 1.5 cm in diameter by 112 cm in length. The engineering prototype compulsator test facility is described, and the sequence of operation of the pulsed power circuit is discussed. Initial measurements of alternator

  7. Compensated pulsed alternators to power electromagnetic railguns

    Microsoft Academic Search

    William C. McCorkle

    1999-01-01

    Electric armaments of coilgun or railgun types require repeated bursts of extremely high power (gigawatts), considerable amounts of energy (tens of megajoules), delivered in several milliseconds. Compensated pulsed alternators, due to their high power and energy densities, have emerged as leading candidates for power supplies for railguns of the future. This paper examines test results of completed compulsator-based systems such

  8. Unionization and Faculty Compensation: Part II

    ERIC Educational Resources Information Center

    Birnbaum, Robert

    1976-01-01

    Previous findings indicate that faculty on the average earn greater compensation increases at unionized institutions than at nonunionized colleges and universities. More recent data suggest that while increases favoring unionized faculty continue in public four-year colleges and independent institutions, they may have stabilized at public…

  9. Improving multiresolution motion compensating hybrid coding

    E-print Network

    Improving multiresolution motion compensating hybrid coding by drift reduction Ulrich Benzler­ pensation is evaluated for the base layer performance in a multiresolution hybrid coding scheme. At constant can be used as an efficient tool to improve the performance of a multiresolution hybrid coding system

  10. Adaptive Filter Applications To Heave Compensation

    Microsoft Academic Search

    D. G. Lainiotis; K. Plataniotis; C. Charalampous

    1992-01-01

    The problem of heave motion compensation is addressed in this paper. A significant class of the Eainiotis partitioning approach is applied and comparisons are made with the Kalman filter based approach, with respect to their computational complexity and performance. It is shown that the linear Lainiotis filter is well suited for on-line implemen- tation, since orders of magnitude reduction of

  11. Actively Damped Heave Compensation (ADHC) system

    Microsoft Academic Search

    QingHui Yuan

    2010-01-01

    In offshore oil and gas exploration and production, high interoperability of underwater components and equipments has become more important in support of Inspection, Maintenance, and Repair (IMR). As drilling goes to deep or ultradeep water, harsh weather leads to an expensive downtime for offshore cranes handling. Active Heave Compensation (AHC) system has been developed to stabilize the crane payload by

  12. A heave compensation approach for offshore cranes

    Microsoft Academic Search

    Jörg Neupert; Tobias Mahl; Bertrand Haessig; Oliver Sawodny; Klaus Schneider

    2008-01-01

    Offshore installations during harsh sea conditions results in rigorous requirements in terms of safety and efficiency for the involved crane system. Hence a heave compensation system based on heave motion prediction and an inversion based control strategy is proposed. The control objective is to let the rope suspended payload track a desired reference trajectory in an earth fixed frame without

  13. Comparing two approaches to compensable flow composition

    E-print Network

    Bruni, Roberto

    at designing a new language but at comparing two main proposals, namely compensating CSP (cCSP) [7] and Sagas cal­ culi [5]. Apart from stylistic differences (e.g., the trace semantics of cCSP and the big step

  14. MOTION COMPENSATION OF INTERFEROMETRIC SYNTHETIC APERTURE RADAR

    E-print Network

    Long, David G.

    radar images. This thesis is an in- vestigation into the improvement of the motion compensation;differential phase from the interferogram. Second, range resampling coregisters the two images. All see my potential all aLong the way. I also want to thank my wife, Julie, and my family for their love

  15. Dispersion Compensation with a Prism-pair

    E-print Network

    Shaked, Yaakov; Pe'er, Avi

    2014-01-01

    We present a detailed calculation of the total dispersion (spectral phase) from a pair of Brewster-cut prisms. This paper aims to aid advanced students in tracking the operation of this major configuration for dispersion-compensation and phase-control of ultra-short pulses.

  16. A multiportal compensator system for IMRT delivery.

    PubMed

    Yoda, Kiyoshi; Aoki, Yukimasa

    2003-05-01

    We have developed a multiportal compensator system for IMRT delivery, comprising a rotational compensator mount for a linac head, cylindrical compensator enclosures positioned in the mount, a vacuum-formed thermoplastic sheet with heavy alloy granules inside the enclosure, and a vacuum thermoforming device. The mount rotates like a revolver by a stepping motor, thus allowing automatic multiportal IMRT without exchanging compensators by human operators during treatment. The thermoforming device has servo-motor-driven 10 x 10 metal rod elements to actualize an arbitrary intensity profile. The thermoplastic sheet is preheated by a built-in biplanar heater and then it is placed over the rod elements. Subsequently, vacuum forming is performed through corner cutouts of the rod elements. After forced cooling down, the heavy alloy granules are fed into the formed sheet. Preliminary experiment using solid water phantoms and an x-ray film has shown that the intensity profile on the film agrees reasonably well with the desired profile. PMID:12772996

  17. Adaptive Temperature Compensation in Circadian Oscillations

    PubMed Central

    François, Paul; Despierre, Nicolas; Siggia, Eric D.

    2012-01-01

    A temperature independent period and temperature entrainment are two defining features of circadian oscillators. A default model of distributed temperature compensation satisfies these basic facts yet is not easily reconciled with other properties of circadian clocks, such as many mutants with altered but temperature compensated periods. The default model also suggests that the shape of the circadian limit cycle and the associated phase response curves (PRC) will vary since the average concentrations of clock proteins change with temperature. We propose an alternative class of models where the twin properties of a fixed period and entrainment are structural and arise from an underlying adaptive system that buffers temperature changes. These models are distinguished by a PRC whose shape is temperature independent and orbits whose extrema are temperature independent. They are readily evolved by local, hill climbing, optimization of gene networks for a common quality measure of biological clocks, phase anticipation. Interestingly a standard realization of the Goodwin model for temperature compensation displays properties of adaptive rather than distributed temperature compensation. PMID:22807663

  18. Compensation, Tuning, and Trimming of MEMS Resonators

    E-print Network

    Ayazi, Farrokh

    Compensation, Tuning, and Trimming of MEMS Resonators Farrokh Ayazi, Roozbeh Tabrizian, Logan Sorenson Center for MEMS and Microsystems Technologies Georgia Institute of Technology Atlanta, GA, USA ayazi@gatech.edu Abstract--Fundamental characteristics of MEMS resonators such as acoustic velocity

  19. 7 CFR 301.74-5 - Compensation.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...compensation for losses associated with the destruction of trees in order to control plum pox pursuant to an...ii) of this section. (2) Owners of fruit tree nurseries. The owner of a fruit tree nursery will be eligible to receive...

  20. 7 CFR 301.74-5 - Compensation.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...compensation for losses associated with the destruction of trees in order to control plum pox pursuant to an...ii) of this section. (2) Owners of fruit tree nurseries. The owner of a fruit tree nursery will be eligible to receive...

  1. 7 CFR 301.74-5 - Compensation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...compensation for losses associated with the destruction of trees in order to control plum pox pursuant to an...ii) of this section. (2) Owners of fruit tree nurseries. The owner of a fruit tree nursery will be eligible to receive...

  2. Changes in Workmen's Compensation Laws in 1973

    ERIC Educational Resources Information Center

    Johnson, Florence C.

    1974-01-01

    Major 1973 State legislative changes of workmen's compensation laws focused on more flexibility and increased levels of benefits, improved medical care and rehabilitation provisions, improved occupational diseases provisions, and increased coverage of farm laborers. Many States adopted amendments to strengthen the administrative procedures of…

  3. On Compensation in Multidimensional Response Modeling

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2012-01-01

    The issue of compensation in multidimensional response modeling is addressed. We show that multidimensional response models are compensatory in their ability parameters if and only if they are monotone. In addition, a minimal set of assumptions is presented under which the MLEs of the ability parameters are also compensatory. In a recent series of…

  4. Tilted cone beam VCT reconstruction algorithm

    NASA Astrophysics Data System (ADS)

    Hsieh, Jiang; Tang, Xiangyang

    2005-04-01

    Reconstruction algorithms for volumetric CT have been the focus of many studies. Several exact and approximate reconstruction algorithms have been proposed for step-and-shoot and helical scanning trajectories to combat cone beam related artifacts. In this paper, we present a closed form cone beam reconstruction formula for tilted gantry data acquisition. Although several algorithms were proposed to compensate for errors induced by the gantry tilt, none of the algorithms addresses the case in which the cone beam geometry is first rebinned to a set of parallel beams prior to the filtered backprojection. Because of the rebinning process, the amount of iso-center adjustment depends not only on the projection angle and tilt angle, but also on the reconstructed pixel location. The proposed algorithm has been tested extensively on both 16 and 64 slice VCT with phantoms and clinical data. The efficacy of the algorithm is clearly demonstrated by the experiments.

  5. Smoothing of respiratory motion traces for motion-compensated radiotherapy

    SciTech Connect

    Ernst, Floris; Schlaefer, Alexander; Schweikard, Achim [Institute for Robotics and Cognitive Systems, University of Luebeck, Ratzeburger Allee 160, Luebeck SH 23538 (Germany)

    2010-01-15

    Purpose: The CyberKnife system has been used successfully for several years to radiosurgically treat tumors without the need for stereotactic fixation or sedation of the patient. It has been shown that tumor motion in the lung, liver, and pancreas can be tracked with acceptable accuracy and repeatability. However, highly precise targeting for tumors in the lower abdomen, especially for tumors which exhibit strong motion, remains problematic. Reasons for this are manifold, like the slow tracking system operating at 26.5 Hz, and using the signal from the tracking camera ''as is''. Since the motion recorded with the camera is used to compensate for system latency by prediction and the predicted signal is subsequently used to infer the tumor position from a correlation model based on x-ray imaging of gold fiducials around the tumor, camera noise directly influences the targeting accuracy. The goal of this work is to establish the suitability of a new smoothing method for respiratory motion traces used in motion-compensated radiotherapy. The authors endeavor to show that better prediction--With a lower rms error of the predicted signal--and/or smoother prediction is possible using this method. Methods: The authors evaluated six commercially available tracking systems (NDI Aurora, PolarisClassic, Polaris Vicra, MicronTracker2 H40, FP5000, and accuTrack compact). The authors first tracked markers both stationary and while in motion to establish the systems' noise characteristics. Then the authors applied a smoothing method based on the a trous wavelet decomposition to reduce the devices' noise level. Additionally, the smoothed signal of the moving target and a motion trace from actual human respiratory motion were subjected to prediction using the MULIN and the nLMS{sub 2} algorithms. Results: The authors established that the noise distribution for a static target is Gaussian and that when the probe is moved such as to mimic human respiration, it remains Gaussian with the exception of the FP5000 and the Aurora systems. The authors also showed that the proposed smoothing method can indeed be used to filter noise. The signal's jitter dropped by as much as 95% depending on the tracking system employed. Subsequently, the 3D prediction error (rms) for a prediction horizon of 150 ms on a synthetic signal dropped by up to 37% when using a normalized LMS prediction algorithm (nLMS{sub 2}) and hardly changed when using a MULIN algorithm. When smoothing a real signal obtained in our laboratory, the improvement of prediction was similar: Up to 30% for both the nLMS{sub 2} and the best MULIN algorithm. The authors also found a noticeable increase in smoothness of the predicted signal, the relative jitter dropped by up to 95% on the real signal, and on the simulated signal. Conclusions: In conclusion, the authors can say that preprocessing of marker data is very useful in motion-compensated radiotherapy since the quality of prediction increases. This will result in better performance of the correlation model. As a side effect, since the prediction of a preprocessed signal is also less noisy, the authors expect less robot vibration resulting in better targeting accuracy and less strain on the robot gears.

  6. Active Wireline Heave Compensation for Ocean Drilling

    NASA Astrophysics Data System (ADS)

    Goldberg, D.; Liu, T.; Swain, K.; Furman, C.; Iturrino, G. J.

    2014-12-01

    The up-and-down heave motion of a ship causes a similar motion on any instruments tethered on wireline cable below it. If the amplitude of this motion is greater than a few tens of cm, significant discrepancy in the depth below the ship is introduced, causing uncertainty in the acquired data. Large and irregular cabled motions also increase the risk of damaging tethered instruments, particularly those with relatively delicate sensors. In 2005, Schlumberger and Deep Down, Inc built an active wireline heave compensator (AHC) system for use onboard the JOIDES Resolution to compensate for heave motion on wireline logging tools deployed in scientific drill holes. The goals for the new AHC system were to (1) design a reliable heave compensation system; and (2) devise a robust and quantitative methodology for routine assessment of compensation efficiency (CE) during wireline operations. Software programs were developed to monitor CE and the dynamics of logging tools in real-time, including system performance under variable parameters such as water depth, sea state, cable length, logging speed and direction. We present the CE results from the AHC system on the JOIDES Resolution during a 5-year period of recent IODP operations and compare the results to those from previous compensation systems deployed during ODP and IODP. Based on new data under heave conditions of ±0.2-2.0 m and water depths of 300-4,800 m in open holes, the system reduces 65-80% of downhole tool displacement under stationary conditions and 50-60% during normal logging operations. Moreover, down/up tool motion at low speeds (300-600 m/h) reduces the system's CE values by 15-20%, and logging down at higher speeds (1,000-1,200 m/h) reduces CE values by 55-65%. Furthermore, the system yields slightly lower CE values of 40-50% without tension feedback of the downhole cable while logging. These results indicate that the new system's compensation efficiency is comparable to or better than previous systems, with additional advantages that include upgradable compensation control software and the capability for continued assessment under varying environmental conditions. Future integration of downhole cable dynamics as an input feedback could further improve CE during logging operations.­

  7. Dynamic compensation in the central Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Hinojosa, Juan Homero; Marsh, Bruce D.

    1988-01-01

    The intermediate-wavelength geoid (lambda similar to 2000 km) and sea-floor topography fields in the central Pacific Ocean were studied in terms of static and dynamic compensation models. Topographic features on the sea-floor with lambda less than 1000 km were found to be compensated both regionally, by the elastic strength of the lithosphere, and locally, by displacing mantle material to reach isostatic adjustment. The larger-scale sea-floor topography and the corresponding geoid anomalies with lambda similar to 2000 km cannot be explained by either local or regional compensation. The topography and the resulting geoid anomaly at this wavelength were modeled by considering the dynamic effects arising from viscous stresses in a layer of fluid with a highly temperature-dependent viscosity for the cases of: (1) surface cooling, and (2) basal heating. In this model, the mechanical properties of the elastic part of the lithosphere were taken into account by considering an activation energy of about 520 kJ/mol in the Arrhenius law for the viscosity. Numerical predictions of the topography, total geoid anomaly, and admittance were obtained, and the results show that the thermal perturbation in the layer, which accounts for the mass deficit, must be located close to the surface to compensate the gravitational effect of the surface deformation. For the case of basal heating, the temperature dependence of viscosity results in a separation of the upper, quasi-rigid lid from the lower mobile fluid, hence inhibiting the development of a compensating thermal perturbation at shallow depths. The results clearly rule out small-scale, upper-mantle convection as the source of these anomalies. Instead, the geophysical observables can be well explained by a shallow, transient thermal perturbation.

  8. 76 FR 49398 - Non-Discrimination in Compensation; Compensation Data Collection Tool

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-10

    ...Office of Federal Contract Compliance Programs...The Office of Federal Contract Compliance Programs...insight into potential problems of compensation discrimination...Office of Federal Contract Compliance Programs...which requires Federal Government contractors and...

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

    E-print Network

    Muslu, Volkan

    2005-01-01

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

  10. Compensator design for improved counterbalancing in high speed atomic force microscopy

    PubMed Central

    Bozchalooi, I. S.; Youcef-Toumi, K.; Burns, D. J.; Fantner, G. E.

    2011-01-01

    High speed atomic force microscopy can provide the possibility of many new scientific observations and applications ranging from nano-manufacturing to the study of biological processes. However, the limited imaging speed has been an imperative drawback of the atomic force microscopes. One of the main reasons behind this limitation is the excitation of the AFM dynamics at high scan speeds, severely undermining the reliability of the acquired images. In this research, we propose a piezo based, feedforward controlled, counter actuation mechanism to compensate for the excited out-of-plane scanner dynamics. For this purpose, the AFM controller output is properly filtered via a linear compensator and then applied to a counter actuating piezo. An effective algorithm for estimating the compensator parameters is developed. The information required for compensator design is extracted from the cantilever deflection signal, hence eliminating the need for any additional sensors. The proposed approach is implemented and experimentally evaluated on the dynamic response of a custom made AFM. It is further assessed by comparing the imaging performance of the AFM with and without the application of the proposed technique and in comparison with the conventional counterbalancing methodology. The experimental results substantiate the effectiveness of the method in significantly improving the imaging performance of AFM at high scan speeds. PMID:22128989

  11. US-LHC IR magnet error analysis and compensation

    SciTech Connect

    Wei, J.; Ptitsin, V.; Pilat, F.; Tepikian, S. [Brookhaven National Lab., Upton, NY (United States); Gelfand, N.; Wan, W.; Holt, J. [Fermi National Accelerator Lab., Batavia, IL (United States)

    1998-08-01

    This paper studies the impact of the insertion-region (IR) magnet field errors on LHC collision performance. Compensation schemes including magnet orientation optimization, body-end compensation, tuning shims, and local nonlinear correction are shown to be highly effective.

  12. 29 CFR 505.3 - Prevailing minimum compensation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...THE NATIONAL ENDOWMENTS FOR THE ARTS AND HUMANITIES § 505.3...the National Endowment for the Arts and the National Endowment...compensation (including fringe benefits) contained in collective bargaining...compensation (including fringe benefits) actually paid to the...

  13. Fast offset compensation for a 10Gbps limit amplifier

    E-print Network

    Crain, Ethan A. (Ethan Alan), 1972-

    2004-01-01

    A novel offset voltage compensation method is presented that significantly modifies the existing tradeoff between control loop bandwidth, and therefore total compensation time, and total output jitter. The proposed system ...

  14. Team Identity and Performance-based Compensation Effects on Performance 

    E-print Network

    Blazovich, Janell L.

    2010-01-16

    This study investigates whether team members work harder and perform better when they are compensated based on both team and individual performance than when compensated based on team or individual performance alone and whether teammates...

  15. 26 CFR 1.162-7 - Compensation for personal services.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...form or method of fixing compensation is not decisive as to deductibility. While any form of contingent compensation invites scrutiny as a possible distribution of earnings of the enterprise, it does not follow that payments on a contingent basis are...

  16. 26 CFR 1.162-7 - Compensation for personal services.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...form or method of fixing compensation is not decisive as to deductibility. While any form of contingent compensation invites scrutiny as a possible distribution of earnings of the enterprise, it does not follow that payments on a contingent basis are...

  17. 26 CFR 1.162-7 - Compensation for personal services.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...form or method of fixing compensation is not decisive as to deductibility. While any form of contingent compensation invites scrutiny as a possible distribution of earnings of the enterprise, it does not follow that payments on a contingent basis are...

  18. 26 CFR 1.162-7 - Compensation for personal services.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...form or method of fixing compensation is not decisive as to deductibility. While any form of contingent compensation invites scrutiny as a possible distribution of earnings of the enterprise, it does not follow that payments on a contingent basis are...

  19. 20 CFR 704.401 - Administration; compensation districts.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  20. Simulation modeling for heave compensation of heavy-duty Semiactive Heave Compensation System

    Microsoft Academic Search

    Xiao Tibing

    2010-01-01

    Heavy-duty Semi-active Heave Compensation System(HSAHCS) is one of necessary device to secure the deep-ocean production in bad ocean condition. In this paper, the simulation model for heave compensation of HSAHCS is built by using the power bond graph theory and the simulation software simulink. The simulation results prove that the simulation model built in this paper is correct.

  1. Re-Planning for Compensator-Based IMRT with Original Compensators

    SciTech Connect

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

    2011-04-01

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

  2. Sales compensation governance: the last frontier of corporate reform.

    PubMed

    Gundy, Peter R; Gaeta, Elizabeth C

    2004-01-01

    The area of sales compensation has remained relatively untouched by recent pressures for compensation reform. This article highlights some of the ways that sales organizations stumble in managing their compensation programs, and why it takes more than a simple tactical fix to address these problems effectively. The authors describe a more structured governance framework that not only identifies and resolves key sales compensation issues, but ultimately safeguards the effectiveness and financial integrity of the sales organization itself. PMID:15015424

  3. Automated hierarchical time gain compensation for in-vivo ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Moshavegh, Ramin; Hemmsen, Martin C.; Martins, Bo; Brandt, Andreas H.; Hansen, Kristoffer L.; Nielsen, Michael B.; Jensen, Jørgen A.

    2015-03-01

    Time gain compensation (TGC) is essential to ensure the optimal image quality of the clinical ultrasound scans. When large fluid collections are present within the scan plane, the attenuation distribution is changed drastically and TGC compensation becomes challenging. This paper presents an automated hierarchical TGC (AHTGC) algorithm that accurately adapts to the large attenuation variation between different types of tissues and structures. The algorithm relies on estimates of tissue attenuation, scattering strength, and noise level to gain a more quantitative understanding of the underlying tissue and the ultrasound signal strength. The proposed algorithm was applied to a set of 44 in vivo abdominal movie sequences each containing 15 frames. Matching pairs of in vivo sequences, unprocessed and processed with the proposed AHTGC were visualized side by side and evaluated by two radiologists in terms of image quality. Wilcoxon signed-rank test was used to evaluate whether radiologists preferred the processed sequences or the unprocessed data. The results indicate that the average visual analogue scale (VAS) is positive ( p-value: 2.34 × 10-13) and estimated to be 1.01 (95% CI: 0.85; 1.16) favoring the processed data with the proposed AHTGC algorithm.

  4. Automatic compensation for the errors of a gyroscopic linear integrating accelerometer

    SciTech Connect

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

    1995-10-01

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

  5. Atmospheric evolution

    NASA Astrophysics Data System (ADS)

    Bolle, H.-J.

    One of the most important boundary conditions imposed on planetary formation theories by planetary atmosphere gas abundances is that the volatiles present are not likely to have undergone a hot phase during early accretion, and must therefore have been added at a later stage if such a hot phase did occur. As a consequence, and in contrast with the survival of primordial or solar abundances in such outer planets as Jupiter, the inner planets have undergone major transformations: (1) on Venus and Mars, water must have been dissociated, resulting in the escape of hydrogen; (2) carbon was probably bound chemically in the Martian crust, while (3) it could not react with Venus crustal materials because of the high temperatures generated by the greenhouse effect; and (4) on the earth, due to intermediate temperatures, the most significant change has been the generation of life, with its attendant transformation of an originally reducing atmosphere into an oxidizing one.

  6. Atmospheric Dust

    NSDL National Science Digital Library

    2014-09-14

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

  7. A computer program for borehole compensation of dual-detector density well logs

    USGS Publications Warehouse

    Scott, James Henry

    1978-01-01

    The computer program described in this report was developed for applying a borehole-rugosity and mudcake compensation algorithm to dual-density logs using the following information: the water level in the drill hole, hole diameter (from a caliper log if available, or the nominal drill diameter if not), and the two gamma-ray count rate logs from the near and far detectors of the density probe. The equations that represent the compensation algorithm and the calibration of the two detectors (for converting countrate or density) were derived specifically for a probe manufactured by Comprobe Inc. (5.4 cm O.D. dual-density-caliper); they are not applicable to other probes. However, equivalent calibration and compensation equations can be empirically determined for any other similar two-detector density probes and substituted in the computer program listed in this report. * Use of brand names in this report does not necessarily constitute endorsement by the U.S. Geological Survey.

  8. Atmosphere Webquest

    NSDL National Science Digital Library

    Mr. Talley

    2011-09-27

    Use the websites and games provided to answer questions, complete diagrams, and learn more about our Earth's atmosphere TOPIC 1 - Weather vs. Climate - Let's start with a game. Open up Online Stopwatch and click on the stopwatch setting. - Use the stopwatch to time yourself as you play through all three levels of The Weather Game. - On your own piece of paper write down how long it took you to pass all ...

  9. 48 CFR 252.217-7004 - Job orders and compensation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

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

  10. 48 CFR 252.217-7004 - Job orders and compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

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

  11. 48 CFR 252.217-7004 - Job orders and compensation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Job orders and compensation. 252.217-7004...Provisions And Clauses 252.217-7004 Job orders and compensation. As prescribed...7104(a), use the following clause: Job Orders and Compensation (MAY 2006)...

  12. 48 CFR 252.217-7004 - Job orders and compensation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  13. 48 CFR 252.217-7004 - Job orders and compensation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

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

  14. Compensated Siting Proposals: Is it Time to Pay Attention?

    Microsoft Academic Search

    Vicki Been

    1994-01-01

    Many proposals to overcome the difficulty of siting locally undesirable land uses (“LULUs”) fairly and efficiently suggest that the problem could be resolved if victims of the siting were adequately compensated for the burdens the LULU imposes. This Article seeks to spur greater attention to the difficult moral and political issues compensation proposals raise by showing that compensation programs are

  15. Compensating for systematic errors in 5-axis NC machining

    Microsoft Academic Search

    Erik L. J. Bohez

    2002-01-01

    The errors introduced during 5-axis machining are higher than the intrinsic repeatability of the machine tool. It is possible to identify such systematic errors and compensate for them, thus achieving higher performance. A group of systematic errors can be compensated for directly in the inverse kinematics equations. Other systematic errors can be combined and compensated for through the total differentials

  16. Presidential Compensation in Higher Education: Policies & Best Practices.

    ERIC Educational Resources Information Center

    Atwell, Robert H.; Wellman, Jane V.

    2000-01-01

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

  17. Friction compensation in servo motor systems using neural networks

    Microsoft Academic Search

    X. Z. Gao; S. J. Ovaska

    1999-01-01

    Compensation of negative effects caused by friction in high precision servo control systems is an important and challenging problem. Conventional compensation methods often rely on an explicit friction model, which is difficult to acquire accurately in practice. We propose a neural network-based compensation scheme to cope with this problem. The visible disturbance resulting from friction is first identified by a

  18. Advanced navigation algorithms for precision landing

    NASA Astrophysics Data System (ADS)

    Zanetti, Renato

    2007-12-01

    A detailed analysis of autonomous navigation algorithms to achieve autonomous precision landing is presented. The problem of integrated attitude determination and inertial navigation is solved. The theoretical results are applied and tested in three different applications. Optimality conditions for constrained quaternion estimation using the Kalman filter are derived. It is common in spacecraft applications to separate the attitude determination from the inertial navigation system. While this approach has worked in the past, it inevitably degrades the navigation performance when the correlations between the two systems are not correctly accounted for. It is shown how to optimally include an attitude determination algorithm into the Kalman filter. When the conditions to achieve optimality are not met, it is shown how to achieve sub-optimality by properly accounting for the correlation. The traditional approach to inertial navigation is to employ the inertial measurement unit (IMU) outputs to propagate the estimated states forward in time, rather then use them to update the state. This approach, known as dead-reckoning, allows for a simplified dynamics model, which in turn reduces the process noise, a contributor to the estimation error. A detailed covariance analysis of dead-reckoning Mars entry navigation is performed. The contribution of various sources of IMU errors are explicitly accounted for and the filter performance is validated through Monte Carlo analysis. The drawback of dead-reckoning is that this approach prevents the inertial measurements from reducing the uncertainty of the estimated states. While this shortcoming can be compensated by the availability of other measurements, it becomes crucial when the IMU is the only sensor to provide measurements. Such a situation arises, for example, during Mars atmospheric entry. In the second application of this work, IMU measurements from a NASA mission are processed in an extended Kalman filter, and the results are compared to dead-reckoning. It is shown that is possible to reduce the uncertainty of the inertial states by filtering the IMU. The final application is lunar descent to landing navigation. In this example the IMU is filtered and the algorithms to include an attitude estimate into the Kalman filter are tested. The design performance is confirmed by Monte Carlo analysis.

  19. SST algorithm based on radiative transfer model

    Microsoft Academic Search

    Mohd Z. Mat Jafri; Khiruddin Abdullah; Alui Bahari

    2001-01-01

    An algorithm for measuring sea surface temperature (SST) without recourse to the in-situ data for calibration has been proposed. The algorithm which is based on the recorded infrared signal by the satellite sensor is composed of three terms, namely, the surface emission, the up-welling radiance emitted by the atmosphere, and the down-welling atmospheric radiance reflected at the sea surface. This

  20. Geometric correction of atmospheric turbulence-degraded video containing moving objects.

    PubMed

    Halder, Kalyan Kumar; Tahtali, Murat; Anavatti, Sreenatha G

    2015-02-23

    Long-distance surveillance is a challenging task because of atmospheric turbulence that causes time-varying image shifts and blurs in images. These distortions become more significant as the imaging distance increases. This paper presents a new method for compensating image shifting in a video sequence while keeping real moving objects in the video unharmed. In this approach, firstly, a highly accurate and fast optical flow technique is applied to estimate the motion vector maps of the input frames and a centroid algorithm is employed to generate a geometrically correct frame in which there is no moving object. The second step involves applying an algorithm for detecting real moving objects in the video sequence and then restoring it with those objects unaffected. The performance of the proposed method is verified by comparing it with that of a state-of-the-art approach. Simulation experiments using both synthetic and real-life surveillance videos demonstrate that this method significantly improves the accuracy of image restoration while preserving moving objects. PMID:25836543

  1. 76 FR 60132 - Proposed Information Collection (Application for Dependency and Indemnity Compensation by Parent...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

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

  2. Evolution of Terrestrial Atmospheres

    NSDL National Science Digital Library

    O'Connell, Robert W.

    This lecture compares terrestrial atmospheres as well as discusses atmospheric processes, atmospheric equilibrium, and the atmospheric development of Mars, Venus, and Earth. It ends with a discussion of natural and unnatural climatic changes.

  3. The "perfect storm" in compensation: convergence of events leads to a greater need to review compensation strategies.

    PubMed

    Jones, Robert B

    2004-01-01

    The recent unprecedented convergence of significant strategic events in the compensation arena has created the need for ongoing and extensive compensation planning. This article reviews the events leading to this point, describes the implications of the results from a recent Aon study with WorldatWork, and suggests what employers can do to successfully navigate the "perfect storm" in compensation. PMID:15015421

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

    PubMed

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

    2014-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  6. Optimal compensation of variable series capacitors for improved economic dispatch in power systems

    SciTech Connect

    Deng, W.; Lie, T.T. [Nanyang Technological Univ., Singapore (Singapore). School of Electrical and Electronic Engineering

    1995-12-31

    This paper presents the development of a mathematical model representation of variable series capacitors which also known as Flexible AC Transmission systems (FACTS) in power system economic dispatch. The objective of this research is to find the optimal locations of FACTS devices for improved economic dispatch. The proposed approach is based on the decomposition-coordination method and the network compensation technique. Taking the advantages of accumulated experience in power system optimization and the existence of the Optimal Power Flow (OPF) software, the software development cost for implementing the proposed algorithm is reduced. In this paper, digital simulation studies on small power systems with and without variable series capacitors were conducted respectively. The purpose of these simulation studies is to assess the effectiveness of the proposed algorithm in minimizing the operating cost and enhancing the system performance. The results of the simulation studies and the proposed algorithm are presented and discussed in greater detail in the paper.

  7. Further evaluation of the constrained least squares electromagnetic compensation method

    NASA Technical Reports Server (NTRS)

    Smith, William T.

    1991-01-01

    Technologies exist for construction of antennas with adaptive surfaces that can compensate for many of the larger distortions caused by thermal and gravitational forces. However, as the frequency and size of reflectors increase, the subtle surface errors become significant and degrade the overall electromagnetic performance. Electromagnetic (EM) compensation through an adaptive feed array offers means for mitigation of surface distortion effects. Implementation of EM compensation is investigated with the measured surface errors of the NASA 15 meter hoop/column reflector antenna. Computer simulations are presented for: (1) a hybrid EM compensation technique, and (2) evaluating the performance of a given EM compensation method when implemented with discretized weights.

  8. Compensation of Strong Thermal Lensing in High Optical Power Cavities

    E-print Network

    C. Zhao; J. Degallaix; L. Ju; Y. Fan; D. G. Blair; B. J. J. Slagmolen; M. B. Gray; C. M. Mow Lowry; D. E. McClellandl; D. J. Hosken; D. Mudge; A. Brooks; J. Munch; P. J. Veitch; M. A. Barton; G. Billingsley

    2006-02-28

    In an experiment to simulate the conditions in high optical power advanced gravitational wave detectors such as Advanced LIGO, we show that strong thermal lenses form in accordance with predictions and that they can be compensated using an intra-cavity compensation plate heated on its cylindrical surface. We show that high finesse ~1400 can be achieved in cavities with internal compensation plates, and that the cavity mode structure can be maintained by thermal compensation. It is also shown that the measurements allow a direct measurement of substrate optical absorption in the test mass and the compensation plate.

  9. Long-Range Beam-Beam Compensation in RHIC

    SciTech Connect

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

    2010-05-01

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

  10. Load positioning system with gravity compensation

    NASA Technical Reports Server (NTRS)

    Hollow, R. H.

    1984-01-01

    A load positioning system with gravity compensation has a servomotor, position sensing feedback potentiometer and velocity sensing tachometer in a conventional closed loop servo arrangement to cause a lead screw and a ball nut to vertically position a load. Gravity compensating components comprise the DC motor, gears, which couple torque from the motor to the lead screw, and constant current power supply. The constant weight of the load applied to the lead screw via the ball nut tend to cause the lead screw to rotate, the constant torque of which is opposed by the constant torque produced by the motor when fed from the constant current source. The constant current is preset as required by the potentiometer to effect equilibration of the load which thereby enables the positioning servomotor to see the load as weightless under both static and dynamic conditions. Positioning acceleration and velocity performance are therefore symmetrical.

  11. Oblique Alfvén instabilities driven by compensated currents

    SciTech Connect

    Malovichko, P. [Main Astronomical Observatory, NASU, Kyiv (Ukraine); Voitenko, Y.; De Keyser, J., E-mail: voitenko@oma.be [Solar-Terrestrial Centre of Excellence, Space Physics Division, Belgian Institute for Space Aeronomy, Ringlaan-3-Avenue Circulaire, B-1180 Brussels (Belgium)

    2014-01-10

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

  12. Intonation and Compensation of Fretted String Instruments

    E-print Network

    Varieschi, Gabriele U

    2009-01-01

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

  13. Stereopsis-Guided Brain Shift Compensation

    Microsoft Academic Search

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

    2005-01-01

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

  14. Distortion compensation techniques for large reflector antennas

    Microsoft Academic Search

    W. A. Imbriale

    2001-01-01

    The high-frequency limit of reflector antennas is usually governed by the magnitude of the surface error. Whereas little can be done for the high-spatial frequency portion of this error, there are various techniques that can be employed to compensate for large-scale surface errors due to gravity induced distortions for ground antennas or thermally induced distortions for spacecraft antennas. This somewhat

  15. Topologies for compact compensated pulsed alternators

    Microsoft Academic Search

    W. A. Walls; M. Driga

    2001-01-01

    Increasing the compactness of compensated pulsed alternators (compulsators) has been an ongoing effort at The University of Texas Center for Electromechanics (UT-CEM) since the mid-1980's, when the U. S. Army interest in electric armaments began to emerge in a significant way. Today, the compulsator is the best approach for achieving compact energy storage and pulsed power generation for multi-MJ, multi-GW

  16. Topologies for compact compensated pulsed alternators

    Microsoft Academic Search

    W. A. Walls; M. D. Driga

    2001-01-01

    Increasing the compactness of compensated pulsed alternators (compulsators) has been an ongoing effort supported by the US Army and others since the mid-1980s, when interest in electric armaments began to emerge. Today, the compulsator is the best approach for achieving compact energy storage and pulsed power generation for multi-MJ, multi-GW applications requiring voltages of up to 15-20 kV and discharge

  17. Value of Heave Compensators to Floating Drilling

    Microsoft Academic Search

    N. Woodall-Mason

    1976-01-01

    Analysis of operation of three rigs equipped with motion compensators indicates a saving of about 16 days per rig year. This is achieved by increasing the drilling limitation to 30-ft seas, which represents a net saving of $400,000 per rig year. Strain gauge monitoring found hook-load variation to be within 2.5 percent for rig heaves of 10 ft or less

  18. Magnetic Compensation of Gravity: Experiments with Oxygen

    Microsoft Academic Search

    G. Pichavant; B. Cariteau; D. Chatain; V. Nikolayev; D. Beysens

    2009-01-01

    The CEA Grenoble, through the ESEME\\/SBT team, has developed a new ground based facility providing magnetic compensation of\\u000a gravity in oxygen. A 2T superconducting magnetic coil has been used to create the magnetic field. The installation is described.\\u000a Well adapted to the heat and mass transfer studies, for example of the various boiling regimes, it permits to enhance the\\u000a understanding

  19. Fuzzy Compensator Using RGA for TRMS Control

    Microsoft Academic Search

    Jih-gau Juang; Wen-kai Liu

    2006-01-01

    \\u000a This paper presents a new approach using fuzzy compensator and PID controller to an experimental propeller setup which is\\u000a called the twin rotor multi-input multi-output system (TRMS). Some previous works ignored the interactions between two axes\\u000a and the controller being designed in horizontal or vertical direction separately. The goal of this study is to stabilize the\\u000a TRMS in significant cross

  20. A general theory for compensating acoustic transducers

    Microsoft Academic Search

    A. K. Newman

    1972-01-01

    Electromechanical and piezoelectric acoustic transducers are shown to be mathematically model-able by a common state-variable formalism. In the three cases considered the matrix differential equations are completely controllable and completely observable, so state-variable compensation is possible. A simplified derivation of the Kalman Observer(1) is presented, illustrating how the internal transducer state-variables are obtained from the observer filter even though they

  1. Genetic Algorithms

    Microsoft Academic Search

    Kumara Sastry; David Goldberg; Graham Kendall

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

  2. Error-compensation measurements on polarization qubits

    E-print Network

    Zhibo Hou; Huangjun Zhu; Guo-Yong Xiang; Chuan-Feng Li; Guang-Can Guo

    2015-03-01

    Systematic errors are inevitable in most measurements performed in real life because of imperfect measurement devices. Reducing systematic errors is crucial to ensuring the accuracy and reliability of measurement results. To this end, delicate error-compensation design is often necessary in addition to device calibration to reduce the dependence of the systematic error on the imperfection of the devices. The art of error-compensation design is well appreciated in nuclear magnetic resonance system by using composite pulses. In contrast, there are few works on reducing systematic errors in quantum optical systems. Here we propose an error-compensation design to reduce the systematic error in projective measurements on a polarization qubit. It can reduce the systematic error to the second order of the phase errors of both the half-wave plate (HWP) and the quarter-wave plate (QWP) as well as the angle error of the HWP. This technique is then applied to experiments on quantum state tomography on polarization qubits, leading to a 20-fold reduction in the systematic error. Our study may find applications in high-precision tasks in polarization optics and quantum optics.

  3. A compensation election for binary social choice

    PubMed Central

    Oprea, Ryan D.; Smith, Vernon L.; Winn, Abel M.

    2007-01-01

    We report experimental results examining the properties of a bidding mechanism, the “Compensation Election,” which is designed to implement a simple binary choice between two options. We may think of the group decision problem as a choice between a new rule and the status quo. The rule and the status quo are each common outcomes that apply across all individuals, but the value or cost that they induce on each individual differs according to each individual's circumstances: some gain, some lose, and others are unaffected by a change to the new from the old. Rather than casting votes, each subject submits a bid reflecting his willingness to pay to induce the group to select one option and the amount he wishes to be paid if the alternative option is selected. The Compensation Election chooses the option that receives the highest sum of bids. We find that, although the Compensation Election allows subjects to strategically bid above their value (or even for the option they do not prefer), such behavior is not the norm. We also find that subjects' bids more truthfully reveal their values when there are more bidders in the election. PMID:17215376

  4. Germany to Compensate Nazi Slave Laborers

    NSDL National Science Digital Library

    Missner, Emily D.

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

  5. Direct Lorentz force compensation flowmeter for electrolytes

    NASA Astrophysics Data System (ADS)

    Vasilyan, S.; Froehlich, Th.

    2014-12-01

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

  6. Genetic Algorithms

    Microsoft Academic Search

    Enrique Alba; Francisco Chicano

    In this chapter we describe the basics of Genetic Algorithms and how they can be used to train Artificial Neural Networks.\\u000a Supervised training of Multilayer Perceptrons for classification problems is considered. We also explain how the Genetic Algorithm\\u000a can be hybridized with other algorithms and present two hybrids between it and two classical algorithms for the neural network\\u000a training: Backpropagation

  7. Algorithm Engineering

    Microsoft Academic Search

    Camil Demetrescu; Irene FinocchiGiuseppe; F. Italianok

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

  8. Atmospheric correction: Computing atmospheric diffuse transmittance

    Microsoft Academic Search

    Jinji Ma; Shizhi Yang; Xianbing Wang; Yanli Qiao

    2006-01-01

    If we can accurately compute the leaving-water radiance and atmospheric diffuse transmittance, we will accurately retrieve the atmosphere optical properties over the case II water by MODIS image. According to the paper by Wang [Wang, Menghua, 1999. Atmospheric correction of ocean color sensors: computing atmospheric diffuse transmittance. Appl. Opt. 38, 451–455] to using the reciprocal equation derived by Yang and

  9. The effect of the light round-trip time on the performance of an adaptive optics turbulence compensation system. Final report

    Microsoft Academic Search

    1992-01-01

    The propagation of a laser beam through atmospheric turbulence can, under many circumstances, be compensated to near diffraction limited levels, by use of an adaptive optics system. In the ideal case, a beacon light source is generated at the aimpoint. This light traverses through the turbulent path back to the aperture. The distribution of phase perturbations in the aperture plane

  10. POAM II retrieval algorithm and error analysis

    Microsoft Academic Search

    J. D. Lumpe; R. M. Bevilacqua; K. W. Hoppel; S. S. Krigman; D. L. Kriebel; D. J. Debrestian; C. E. Randall; D. W. Rusch; C. Brogniez; R. Ramananahérisoa; E. P. Shettle; J. J. Olivero; J. Lenoble; P. Pruvost

    1997-01-01

    We present a detailed discussion of the version 5 algorithms used to analyze the Polar Ozone and Aerosol Measurement II (POAM II) solar occultation data. As this version is primarily an ozone and aerosol retrieval, the scope of the paper is limited to these constituents. Forward model algorithms for calculating atmospheric transmittance in the nine POAM II spectral channels are

  11. Profiling atmospheric water vapor by microwave radiometry

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Wilheit, T. T.; Szejwach, G.; Gesell, L. H.; Nieman, R. A.; Niver, D. S.; Krupp, B. M.; Gagliano, J. A.; King, J. L.

    1983-01-01

    High-altitude microwave radiometric observations at frequencies near 92 and 183.3 GHz were used to study the potential of retrieving atmospheric water vapor profiles over both land and water. An algorithm based on an extended kalman-Bucy filter was implemented and applied for the water vapor retrieval. The results show great promise in atmospheric water vapor profiling by microwave radiometry heretofore not attainable at lower frequencies.

  12. Retrieving Atmospheric Profiles Data in the Presence of Clouds from Hyperspectral Remote Sensing Data

    NASA Technical Reports Server (NTRS)

    Liu, Xu; Larar, Allen M.; Zhou, Daniel K.; Kizer, Susan H.; Wu, Wan; Barnet, Christopher; Divakarla, Murty; Guo, Guang; Blackwell, Bill; Smith, William L.; Yang, Ping; Gu, Degui

    2011-01-01

    Different methods for retrieving atmospheric profiles in the presence of clouds from hyperspectral satellite remote sensing data will be described. We will present results from the JPSS cloud-clearing algorithm and NASA Langley cloud retrieval algorithm.

  13. Predictors of Energy Compensation during Exercise Interventions: A Systematic Review

    PubMed Central

    Riou, Marie-Ève; Jomphe-Tremblay, Simon; Lamothe, Gilles; Stacey, Dawn; Szczotka, Agnieszka; Doucet, Éric

    2015-01-01

    Weight loss from exercise-induced energy deficits is usually less than expected. The objective of this systematic review was to investigate predictors of energy compensation, which is defined as body energy changes (fat mass and fat-free mass) over the total amount of exercise energy expenditure. A search was conducted in multiple databases without date limits. Of 4745 studies found, 61 were included in this systematic review with a total of 928 subjects. The overall mean energy compensation was 18% ± 93%. The analyses indicated that 48% of the variance of energy compensation is explained by the interaction between initial fat mass, age and duration of exercise interventions. Sex, frequency, intensity and dose of exercise energy expenditure were not significant predictors of energy compensation. The fitted model suggested that for a shorter study duration, lower energy compensation was observed in younger individuals with higher initial fat mass (FM). In contrast, higher energy compensation was noted for younger individuals with lower initial FM. From 25 weeks onward, energy compensation was no longer different for these predictors. For studies of longer duration (about 80 weeks), the energy compensation approached 84%. Lower energy compensation occurs with short-term exercise, and a much higher level of energy compensation accompanies long-term exercise interventions. PMID:25988763

  14. The digital compensation technology system for automotive pressure sensor

    NASA Astrophysics Data System (ADS)

    Guo, Bin; Li, Quanling; Lu, Yi; Luo, Zai

    2010-12-01

    Piezoresistive pressure sensor be made of semiconductor silicon based on Piezoresistive phenomenon, has many characteristics. But since the temperature effect of semiconductor, the performance of silicon sensor is also changed by temperature, and the pressure sensor without temperature drift can not be produced at present. This paper briefly describe the principles of sensors, the function of pressure sensor and the various types of compensation method, design the detailed digital compensation program for automotive pressure sensor. Simulation-Digital mixed signal conditioning is used in this dissertation, adopt signal conditioning chip MAX1452. AVR singlechip ATMEGA128 and other apparatus; fulfill the design of digital pressure sensor hardware circuit and singlechip hardware circuit; simultaneously design the singlechip software; Digital pressure sensor hardware circuit is used to implementing the correction and compensation of sensor; singlechip hardware circuit is used to implementing to controll the correction and compensation of pressure sensor; singlechip software is used to implementing to fulfill compensation arithmetic. In the end, it implement to measure the output of sensor, and contrast to the data of non-compensation, the outcome indicates that the compensation precision of compensated sensor output is obviously better than non-compensation sensor, not only improving the compensation precision but also increasing the stabilization of pressure sensor.

  15. The digital compensation technology system for automotive pressure sensor

    NASA Astrophysics Data System (ADS)

    Guo, Bin; Li, Quanling; Lu, Yi; Luo, Zai

    2011-05-01

    Piezoresistive pressure sensor be made of semiconductor silicon based on Piezoresistive phenomenon, has many characteristics. But since the temperature effect of semiconductor, the performance of silicon sensor is also changed by temperature, and the pressure sensor without temperature drift can not be produced at present. This paper briefly describe the principles of sensors, the function of pressure sensor and the various types of compensation method, design the detailed digital compensation program for automotive pressure sensor. Simulation-Digital mixed signal conditioning is used in this dissertation, adopt signal conditioning chip MAX1452. AVR singlechip ATMEGA128 and other apparatus; fulfill the design of digital pressure sensor hardware circuit and singlechip hardware circuit; simultaneously design the singlechip software; Digital pressure sensor hardware circuit is used to implementing the correction and compensation of sensor; singlechip hardware circuit is used to implementing to controll the correction and compensation of pressure sensor; singlechip software is used to implementing to fulfill compensation arithmetic. In the end, it implement to measure the output of sensor, and contrast to the data of non-compensation, the outcome indicates that the compensation precision of compensated sensor output is obviously better than non-compensation sensor, not only improving the compensation precision but also increasing the stabilization of pressure sensor.

  16. Compensator quality control with an amorphous silicon EPID.

    PubMed

    Menon, Geetha V; Sloboda, Ron S

    2003-07-01

    The calibration and quality control of compensators is conventionally performed with an ion chamber in a water-equivalent phantom. In our center, the compensator factor and four off-axis fluence ratios are measured to verify the central axis beam modulation and orientation of the compensator. Here we report the investigation of an alternative technique for compensator quality control using an amorphous silicon electronic portal imaging device (a-Si EPID). Preliminary experiments were performed to identify appropriate EPID operating parameters for this relative dosimetric study and also to quantify EPID operation. The pixel value versus energy fluence response of the EPID for both open and compensated fields was then determined, and expressed via calibration curves. For open fields the response was seen to be linear, whereas for compensated fields it exhibited a small quadratic component. To account for field size effects, we measured EPID scatter factors. These exhibited small but non-negligible dependencies on compensator thickness and source-detector distance. Finally, a number of test and clinical compensators were evaluated to assess the suitability of the EPID for compensator quality control. Our results indicate that the a-Si EPID can measure clinical compensator factors and off-axis energy fluence ratios to within 2% of values measured by a Farmer chamber on average, and so is a suitable ion chamber replacement. PMID:12906200

  17. Atmosphere Analyzer

    NASA Technical Reports Server (NTRS)

    1982-01-01

    California Measurements, Inc.'s model PC-2 Aerosol Particle Analyzer is produced in both airborne and ground-use versions. Originating from NASA technology, it is a quick and accurate method of detecting minute amounts of mass loadings on a quartz crystal -- offers utility as highly sensitive detector of fine particles suspended in air. When combined with suitable air delivery system, it provides immediate information on the size distribution and mass concentrations of aerosols. William Chiang, obtained a NASA license for multiple crystal oscillator technology, and initially developed a particle analyzer for NASA use with Langley Research Center assistance. Later his company produced the modified PC-2 for commercial applications Brunswick Corporation uses the device for atmospheric research and in studies of smoke particles in Fires. PC-2 is used by pharmaceutical and chemical companies in research on inhalation toxicology and environmental health. Also useful in testing various filters for safety masks and nuclear installations.

  18. The controllability of the aeroassist flight experiment atmospheric skip trajectory

    NASA Technical Reports Server (NTRS)

    Wood, R.

    1989-01-01

    The Aeroassist Flight Experiment (AFE) will be the first vehicle to simulate a return from geosynchronous orbit, deplete energy during an aerobraking maneuver, and navigate back out of the atmosphere to a low earth orbit It will gather scientific data necessary for future Aeroasisted Orbitl Transfer Vehicles (AOTV's). Critical to mission success is the ability of the atmospheric guidance to accurately attain a targeted post-aeropass orbital apogee while nulling inclination errors and compensating for dispersions in state, aerodynamic, and atmospheric parameters. In typing to satisfy mission constraints, atmospheric entry-interface (EI) conditions, guidance gains, and trajectory. The results of the investigation are presented; emphasizing the adverse effects of dispersed atmospheres on trajectory controllability.

  19. MAP detection for impairment compensation in coherent WDM systems.

    PubMed

    Zhao, J; Ellis, A D

    2009-08-01

    We propose a novel recursive-algorithm based maximum a posteriori probability (MAP) detector in spectrally-efficient coherent wavelength division multiplexing (CoWDM) systems, and investigate its performance in a 1-bit/s/Hz on-off keyed (OOK) system limited by optical-signal-to-noise ratio. The proposed method decodes each sub-channel using the signal levels not only of the particular sub-channel but also of its adjacent sub-channels, and therefore can effectively compensate deterministic inter-sub-channel crosstalk as well as inter-symbol interference arising from narrow-band filtering and chromatic dispersion (CD). Numerical simulation of a five-channel OOK-based CoWDM system with 10Gbit/s per channel using either direct or coherent detection shows that the MAP decoder can eliminate the need for phase control of each optical carrier (which is necessarily required in a conventional CoWDM system), and greatly relaxes the spectral design of the demultiplexing filter at the receiver. It also significantly improves back-to-back sensitivity and CD tolerance of the system. PMID:19654745

  20. Coherent Polarization-Division-Multiplexed QPSK Receiver With Fractionally Spaced CMA for PMD Compensation

    Microsoft Academic Search

    Noriaki Kaneda; Andreas Leven

    2009-01-01

    A digital coherent polarization-division-multiplexed quadrature phase-shift keying receiver with a fractionally spaced constant modulus algorithm (CMA) is implemented in a field-programmable gated array. Real-time measurements at 5 Gb\\/s demonstrate that polarization-mode dispersion can be effectively compensated with multiple numbers of taps when the received data is two-fold over-sampled. With a four-tap CMA, the 1-dB optical signal-to-noise ratio penalty point extends