Optimal modified tracking performance for MIMO networked control systems with communication constraints.

PubMed

Wu, Jie; Zhou, Zhu-Jun; Zhan, Xi-Sheng; Yan, Huai-Cheng; Ge, Ming-Feng

2017-05-01

This paper investigates the optimal modified tracking performance of multi-input multi-output (MIMO) networked control systems (NCSs) with packet dropouts and bandwidth constraints. Some explicit expressions are obtained by using co-prime factorization and the spectral decomposition technique. The obtained results show that the optimal modified tracking performance is related to the intrinsic properties of a given plant such as non-minimum phase (NMP) zeros, unstable poles, and their directions. Furthermore, the modified factor, packet dropouts probability and bandwidth also impact the optimal modified tracking performance of the NCSs. The optimal modified tracking performance with channel input power constraint is obtained by searching through all stabilizing two-parameter compensator. Finally, some typical examples are given to illustrate the effectiveness of the theoretical results. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

COMPARISON OF DIRECT AND INDIRECT IMPACTS OF FECAL CONTAMINATION IN TWO DIFFERENT WATERSHEDS

EPA Science Inventory

There are many environmental parameters that could affect the accuracy of microbial source tracking (MST) methods. Spatial and temporal determinants are among the most common factors missing in MST studies. To understand how spatial and temporal variability affect the level of fe...

Dynamic simulation of train-truck collision at level crossings

NASA Astrophysics Data System (ADS)

Ling, Liang; Guan, Qinghua; Dhanasekar, Manicka; Thambiratnam, David P.

2017-01-01

Trains crashing onto heavy road vehicles stuck across rail tracks are more likely occurrences at level crossings due to ongoing increase in the registration of heavy vehicles and these long heavy vehicles getting caught in traffic after partly crossing the boom gate; these incidents lead to significant financial losses and societal costs. This paper presents an investigation of the dynamic responses of trains under frontal collision on road trucks obliquely stuck on rail tracks at level crossings. This study builds a nonlinear three-dimensional multi-body dynamic model of a passenger train colliding with an obliquely stuck road truck on a ballasted track. The model is first benchmarked against several train dynamics packages and its predictions of the dynamic response and derailment potential are shown rational. A geometry-based derailment assessment criterion is applied to evaluate the derailment behaviour of the frontal obliquely impacted trains under different conditions. Sensitivities of several key influencing parameters, such as the train impact speed, the truck mass, the friction at truck tyres, the train-truck impact angle, the contact friction at the collision zone, the wheel/rail friction and the train suspension are reported.

A pseudo-noise transponder design for low data rate users of the tracking and data relay satellite system

NASA Technical Reports Server (NTRS)

Birch, J. N.

1971-01-01

A compromise optimum design for the low data rate users of the Tracking and Data Relay Satellite System (TDRSS) is presented. Design goals for the TDRSS are employed in this report to arrive at the transponder design. Multipath, R.F.I., antenna pattern anomolies, other user signals, and other definable degrading factors are included as trade-off parameters in the design. Synchronization, emergency voice, user stabilization, polarization diversity and error control coding are also considered and their impact on the transponder design is evaluated.

Heliostat field cost reduction by `slope drive' optimization

NASA Astrophysics Data System (ADS)

Arbes, Florian; Weinrebe, Gerhard; Wöhrbach, Markus

2016-05-01

An algorithm to optimize power tower heliostat fields employing heliostats with so-called slope drives is presented. It is shown that a field using heliostats with the slope drive axes configuration has the same performance as a field with conventional azimuth-elevation tracking heliostats. Even though heliostats with the slope drive configuration have a limited tracking range, field groups of heliostats with different axes or different drives are not needed for different positions in the heliostat field. The impacts of selected parameters on a benchmark power plant (PS10 near Seville, Spain) are analyzed.

Inverted Apatite (U-Th)/He and Fission-track Dates from the Rae craton, Baffin Island, Canada and Implications for Apatite Radiation Damage-He Diffusivity Models

NASA Astrophysics Data System (ADS)

Ault, A. K.; Reiners, P. W.; Thomson, S. N.; Miller, G. H.

2015-12-01

Coupled apatite (U-Th)/He and fission-track (AFT) thermochronology data from the same sample can be used to decipher complex low temperature thermal histories and evaluate compatibility between these two methods. Existing apatite He damage-diffusivity models parameterize radiation damage annealing as fission-track annealing and yield inverted apatite He and AFT dates for samples with prolonged residence in the He partial retention zone. Apatite chemistry also impacts radiation damage and fission-track annealing, temperature sensitivity, and dates in both systems. We present inverted apatite He and AFT dates from the Rae craton, Baffin Island, Canada, that cannot be explained by apatite chemistry or existing damage-diffusivity and fission track models. Apatite He dates from 34 individual analyses from 6 samples range from 237 ± 44 Ma to 511 ± 25 Ma and collectively define a positive date-eU relationship. AFT dates from these same samples are 238 ± 15 Ma to 350 ± 20 Ma. These dates and associated track length data are inversely correlated and define the left segment of a boomerang diagram. Three of the six samples with 20-90 ppm eU apatite grains yield apatite He and AFT dates inverted by 300 million years. These samples have average apatite Cl chemistry of ≤0.02 wt.%, with no correlation between Cl content and Dpar. Thermal history simulations using geologic constraints, an apatite He radiation damage accumulation and annealing model, apatite He dates with the range of eU values, and AFT date and track length data, do not yield any viable time-temperature paths. Apatite He and AFT data modeled separately predict thermal histories with Paleozoic-Mesozoic peaks reheating temperatures differing by ≥15 °C. By modifying the parameter controlling damage annealing (Rmr0) from the canonical 0.83 to 0.5-0.6, forward models reproduce the apatite He date-eU correlation and AFT dates with a common thermal history. Results imply apatite radiation damage anneals at higher temperatures than fission-track damage and the impact on coupled apatite He and AFT dates is magnified for protracted cooling histories. Further experimental and field-based tests are important for refining radiation damage and fission-track annealing parameters for accurate interpretation of apatite He- and AFT-derived thermal histories.

Aeroelastic considerations for torsionally soft rotors

NASA Technical Reports Server (NTRS)

Mantay, W. R.; Yeager, W. T., Jr.

1986-01-01

A research study was initiated to systematically determine the impact of selected blade tip geometric parameters on conformable rotor performance and loads characteristics. The model articulated rotors included baseline and torsionally soft blades with interchangeable tips. Seven blade tip designs were evaluated on the baseline rotor and six tip designs were tested on the torsionally soft blades. The designs incorporated a systemmatic variation in geometric parameters including sweep, taper, and anhedral. The rotors were evaluated in the NASA Langley Transonic Dynamics Tunnel at several advance ratios, lift and propulsive force values, and tip Mach numbers. A track sensitivity study was also conducted at several advance ratios for both rotors. Based on the test results, tip parameter variations generated significant rotor performance and loads differences for both baseline and torsionally soft blades. Azimuthal variation of elastic twist generated by variations in the tip parameters strongly correlated with rotor performance and loads, but the magnitude of advancing blade elastic twist did not. In addition, fixed system vibratory loads and rotor track for potential conformable rotor candidates appears very sensitive to parametric rotor changes.

Tracking and characterizing the head motion of unanaesthetized rats in positron emission tomography

PubMed Central

Kyme, Andre; Meikle, Steven; Baldock, Clive; Fulton, Roger

2012-01-01

Positron emission tomography (PET) is an important in vivo molecular imaging technique for translational research. Imaging unanaesthetized rats using motion-compensated PET avoids the confounding impact of anaesthetic drugs and enables animals to be imaged during normal or evoked behaviour. However, there is little published data on the nature of rat head motion to inform the design of suitable marker-based motion-tracking set-ups for brain imaging—specifically, set-ups that afford close to uninterrupted tracking. We performed a systematic study of rat head motion parameters for unanaesthetized tube-bound and freely moving rats with a view to designing suitable motion-tracking set-ups in each case. For tube-bound rats, using a single appropriately placed binocular tracker, uninterrupted tracking was possible greater than 95 per cent of the time. For freely moving rats, simulations and measurements of a live subject indicated that two opposed binocular trackers are sufficient (less than 10% interruption to tracking) for a wide variety of behaviour types. We conclude that reliable tracking of head pose can be achieved with marker-based optical-motion-tracking systems for both tube-bound and freely moving rats undergoing PET studies without sedation. PMID:22718992

A RSSI-based parameter tracking strategy for constrained position localization

NASA Astrophysics Data System (ADS)

Du, Jinze; Diouris, Jean-François; Wang, Yide

2017-12-01

In this paper, a received signal strength indicator (RSSI)-based parameter tracking strategy for constrained position localization is proposed. To estimate channel model parameters, least mean squares method (LMS) is associated with the trilateration method. In the context of applications where the positions are constrained on a grid, a novel tracking strategy is proposed to determine the real position and obtain the actual parameters in the monitored region. Based on practical data acquired from a real localization system, an experimental channel model is constructed to provide RSSI values and verify the proposed tracking strategy. Quantitative criteria are given to guarantee the efficiency of the proposed tracking strategy by providing a trade-off between the grid resolution and parameter variation. The simulation results show a good behavior of the proposed tracking strategy in the presence of space-time variation of the propagation channel. Compared with the existing RSSI-based algorithms, the proposed tracking strategy exhibits better localization accuracy but consumes more calculation time. In addition, a tracking test is performed to validate the effectiveness of the proposed tracking strategy.

Automation of PCXMC and ImPACT for NASA Astronaut Medical Imaging Dose and Risk Tracking

NASA Technical Reports Server (NTRS)

Bahadori, Amir; Picco, Charles; Flores-McLaughlin, John; Shavers, Mark; Semones, Edward

2011-01-01

To automate astronaut organ and effective dose calculations from occupational X-ray and computed tomography (CT) examinations incorporating PCXMC and ImPACT tools and to estimate the associated lifetime cancer risk per the National Council on Radiation Protection & Measurements (NCRP) using MATLAB(R). Methods: NASA follows guidance from the NCRP on its operational radiation safety program for astronauts. NCRP Report 142 recommends that astronauts be informed of the cancer risks from reported exposures to ionizing radiation from medical imaging. MATLAB(R) code was written to retrieve exam parameters for medical imaging procedures from a NASA database, calculate associated dose and risk, and return results to the database, using the Microsoft .NET Framework. This code interfaces with the PCXMC executable and emulates the ImPACT Excel spreadsheet to calculate organ doses from X-rays and CTs, respectively, eliminating the need to utilize the PCXMC graphical user interface (except for a few special cases) and the ImPACT spreadsheet. Results: Using MATLAB(R) code to interface with PCXMC and replicate ImPACT dose calculation allowed for rapid evaluation of multiple medical imaging exams. The user inputs the exam parameter data into the database and runs the code. Based on the imaging modality and input parameters, the organ doses are calculated. Output files are created for record, and organ doses, effective dose, and cancer risks associated with each exam are written to the database. Annual and post-flight exposure reports, which are used by the flight surgeon to brief the astronaut, are generated from the database. Conclusions: Automating PCXMC and ImPACT for evaluation of NASA astronaut medical imaging radiation procedures allowed for a traceable and rapid method for tracking projected cancer risks associated with over 12,000 exposures. This code will be used to evaluate future medical radiation exposures, and can easily be modified to accommodate changes to the risk calculation procedure.

Adaptive tracking for complex systems using reduced-order models

NASA Technical Reports Server (NTRS)

Carnigan, Craig R.

1990-01-01

Reduced-order models are considered in the context of parameter adaptive controllers for tracking workspace trajectories. A dual-arm manipulation task is used to illustrate the methodology and provide simulation results. A parameter adaptive controller is designed to track a payload trajectory using a four-parameter model instead of the full-order, nine-parameter model. Several simulations with different payload-to-arm mass ratios are used to illustrate the capabilities of the reduced-order model in tracking the desired trajectory.

Adaptive tracking for complex systems using reduced-order models

NASA Technical Reports Server (NTRS)

Carignan, Craig R.

1990-01-01

Reduced-order models are considered in the context of parameter adaptive controllers for tracking workspace trajectories. A dual-arm manipulation task is used to illustrate the methodology and provide simulation results. A parameter adaptive controller is designed to track the desired position trajectory of a payload using a four-parameter model instead of a full-order, nine-parameter model. Several simulations with different payload-to-arm mass ratios are used to illustrate the capabilities of the reduced-order model in tracking the desired trajectory.

Maintenance of the catalog of artificial objects in space.

NASA Astrophysics Data System (ADS)

Khutorovskij, Z. N.

1994-01-01

The catalog of artificial objects in space (AOS) is useful for estimating the safety of space flights, for constructing temporal and spatial models of the flux of AOS, for determining when and where dangerous AOS will break up, for tracking inoperative instruments and space stations, for eliminating false alarms that are triggered by observations of AOS in the Ballistic Missile Early Warning System and in the Anti-Missile system, etc. At present, the Space Surveillance System (located in the former USSR) automatically maintains a catalog consisting of more than 5000 AOS with dimensions of at least 10 cm. The orbital parameters are continuously updated from radar tracking data. The author describes the software which is used to process the information. He presents some of the features of the system itself, including the number of objects in various stages of the tracking process, the orbital parameters of AOS which break up, and how the fragments are detected, the accuracy of tracking and predicting the orbits of the AOS, and the accuracy with which we can estimate when and where an AOS will break up. As an example, the author presents the results of determination of the time when the orbiting complex Salyut-7 - Kosmos-1686 will break up, and where it will impact.

Relating centrality to impact parameter in nucleus-nucleus collisions

NASA Astrophysics Data System (ADS)

Das, Sruthy Jyothi; Giacalone, Giuliano; Monard, Pierre-Amaury; Ollitrault, Jean-Yves

2018-01-01

In ultrarelativistic heavy-ion experiments, one estimates the centrality of a collision by using a single observable, say n , typically given by the transverse energy or the number of tracks observed in a dedicated detector. The correlation between n and the impact parameter b of the collision is then inferred by fitting a specific model of the collision dynamics, such as the Glauber model, to experimental data. The goal of this paper is to assess precisely which information about b can be extracted from data without any specific model of the collision. Under the sole assumption that the probability distribution of n for a fixed b is Gaussian, we show that the probability distribution of the impact parameter in a narrow centrality bin can be accurately reconstructed up to 5 % centrality. We apply our methodology to data from the Relativistic Heavy Ion Collider and the Large Hadron Collider. We propose a simple measure of the precision of the centrality determination, which can be used to compare different experiments.

Assessing Impact of High-Dose Pitavastatin on Carotid Artery Elasticity with Speckle-Tracking Strain Imaging.

PubMed

Kim, Chee Hae; Wang, Shuang; Park, Jun-Bean; Jung, Keun-Hwa; Yoon, Yeonyee E; Lee, Seung-Pyo; Kim, Hyung-Kwan; Kim, Yong-Jin; Cho, Goo-Yeong; Sohn, Dae-Won

2018-03-07

Speckle-tracking imaging has been introduced for the precise assessment of vessel mechanics. However, there are no data on the role of this imaging tool in assessing the changes in vasculature with statin therapy, which is known to enhance vascular elasticity. This study was a prospective study including 48 statin-naïve patients (age, 58.2±8.4 years; 29.2% male) with hypercholesterolemia. Circumferential carotid artery strain (CAS) and stiffness index (β 2 ) were measured using speckle-tracking imaging before and after 3 months of high-dose pitavastatin treatment (4 mg daily). For the comparison, we measured conventional carotid elasticity parameters and intima-media thickness using B-mode ultrasound at the same time points. Compared with baseline, there was significant improvement in circumferential CAS (2.98%±1.18% to 3.40%±1.43%, p=0.008) and β 2 (0.19±0.07 to 0.17±0.08, p=0.047) after statin therapy. Contrariwise, there were no significant changes in all conventional carotid elasticity metrics and intima-media thickness. When stratifying patients into two subgroups by 10 year atherosclerotic cardiovascular disease (ASCVD) risk, speckle-tracking-derived circumferential CAS and β 2 improved significantly only in patients with ASCVD risk ≥ 7.5%. Short-term treatment with high-dose pitavastatin improved carotid artery elasticity measured by speckle-tracking method, but not conventional parameters by B-mode ultrasound. Speckle-tracking-based measurements may allow the early noninvasive assessment of statin effects on vascular function in hypercholesterolemic patients.

Atmospheric propagation at larger lateral distances from the flight track

NASA Technical Reports Server (NTRS)

Pierce, Allan D.

1994-01-01

Sonic booms received on the ground tend to be restricted to a region of finite lateral extent below the flight track. This occurs because of refraction and because the effective speed of sound, even with winds taken into account, decreases with altitude in the lower atmosphere. Not all rays proceeding initially downwards from the flight track within an allowable range of initial directions will reach the ground. The restricted region which can be reached by rays impacting the ground is known as the primary carpet. However, weak rumbles are heard in the nominal shadow zone beyond the edge of this carpet. A full wave theory is necessary for explaining waveforms in that region, and the present paper gives a matched asymptotic expansion technique for a suitable approximate full wave theory that involves a relatively small number of parameters. The outer solution is derived from the structure of the system of rays that impact near the corridor edge; the inner solution involves a solution of the parabolic equation and results in the special functions encountered in the diffraction of sound over the tops of hills.

Nuclear Track Detector Characterization via Alpha-Spectrometry for Radioprotection Use

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morelli, D.; Imme, G.; Catalano, R.

2011-12-13

Solid Nuclear Track Detectors (SNTDs), CR-39 type, are usually adopted to monitor radon gas concentrations. In order to characterize the detectors according to track geometrical parameters, detectors were irradiated inside a vacuum chamber by alpha particles at twelve energy values, obtained by different Mylar foils in front of a {sup 241}Am source. The alpha energy values were verified using a Si detector. After the exposure to the alpha particles, the detectors were chemically etched to enlarge the tracks, which were then analyzed by means of a semiautomatic system composed of an optical microscope equipped with a CCD camera connected tomore » a personal computer to store images. A suitable routine analyzed the track parameters: major and minor axis length and mean grey level, allowing us to differentiate tracks according to the incident alpha energy and then to individuate the discrimination factors for radon alpha tracks. The combined use of geometrical and optical parameters allows one to overcome the ambiguity in the alpha energy determination due to the non-monotonicity of each parameter versus energy. After track parameter determination, a calibration procedure was performed by means of a radon chamber. The calibration was verified through an inter-comparing survey.« less

Simulation of vertical dynamic vehicle-track interaction in a railway crossing using Green's functions

NASA Astrophysics Data System (ADS)

Li, X.; Torstensson, P. T.; Nielsen, J. C. O.

2017-12-01

Vertical dynamic vehicle-track interaction in the through route of a railway crossing is simulated in the time domain based on a Green's function approach for the track in combination with an implementation of Kalker's variational method to solve the non-Hertzian, and potentially multiple, wheel-rail contact. The track is described by a linear, three-dimensional and non-periodic finite element model of a railway turnout accounting for the variations in rail cross-sections and sleeper lengths, and including baseplates and resilient elements. To reduce calculation time due to the complexity of the track model, involving a large number of elements and degrees-of-freedom, a complex-valued modal superposition with a truncated mode set is applied before the impulse response functions are calculated at various positions along the crossing panel. The variation in three-dimensional contact geometry of the crossing and wheel is described by linear surface elements. In each time step of the contact detection algorithm, the lateral position of the wheelset centre is prescribed but the contact positions on wheel and rail are not, allowing for an accurate prediction of the wheel transition between wing rail and crossing rail. The method is demonstrated by calculating the wheel-rail impact load and contact stress distribution for a nominal S1002 wheel profile passing over a nominal crossing geometry. A parameter study is performed to determine the influence of vehicle speed, rail pad stiffness, lateral wheelset position and wheel profile on the impact load generated at the crossing. It is shown that the magnitude of the impact load is more influenced the wheel-rail contact geometry than by the selection of rail pad stiffness.

The ATLAS Inner Detector commissioning and calibration

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2010-08-20

The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7. 6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes,more » specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22.1±0.9 μm and a relative momentum resolution σ p/p=(4. 83 ± 0.16)×10 -4 GeV -1×p T have been measured for high momentum tracks.« less

Ocean Tracks: Investigating Marine Migrations in a Changing Ocean

NASA Astrophysics Data System (ADS)

Krumhansl, R.; Kochevar, R. E.; Aluwihare, L.; Bardar, E. W.; Hirsch, L.; Hoyle, C.; Krumhansl, K.; Louie, J.; Madura, J.; Mueller-Northcott, J.; Peach, C. L.; Trujillo, A.; Winney, B.; Zetterlind, V.; Busey, A.

2015-12-01

The availability of scientific data sets online opens up exciting new opportunities to raise students' understanding of the worlds' oceans and the potential impacts of climate change. The Oceans of Data Institute at EDC; Stanford University; and the Scripps Institution of Oceanography have been collaborating, with the support of three National Science Foundation grants over the past 5 years, to bring marine science data sets into high school and undergraduate classrooms. These efforts have culminated in the development of a web-based student interface to data from the Tagging of Pacific Predators (TOPP) program, NOAA's Global Drifter Program, and NASA Earth-orbiting satellites through a student-friendly Web interface, customized data analysis tools, multimedia supports, and course modules. Ocean Tracks (http://oceantracks.org), which incorporates design principles based on a broad range of research findings in fields such as cognitive science, visual design, mathematics education and learning science, focuses on optimizing students' opportunities to focus their cognitive resources on viewing and comparing data to test hypotheses, while minimizing the time spent on downloading, filtering and creating displays. Ocean Tracks allows students to display the tracks of elephant seals, white sharks, Bluefin tuna, albatross, and drifting buoys along with sea surface temperature, chlorophyll-A, bathymetry, ocean currents, and human impacts overlays. A graphing tool allows students to dynamically display parameters associated with the track such as speed, deepest daily dive and track tortuosity (curviness). These interface features allow students to engage in investigations that mirror those currently being conducted by scientists to understand the broad-scale effects of changes in climate and other human activities on ocean ecosystems. In addition to supporting the teaching of the Ocean and Climate Literacy principles, high school curriculum modules facilitate the teaching of content, practices and cross-cutting concepts in the Framework for K-12 Science Education. Undergraduate modules currently under development support the teaching of content related to marine productivity, ocean circulation and upwelling, animal-environment interactions, ocean ecosystems, and human impacts.

Subnanosecond GPS-based clock synchronization and precision deep-space tracking

NASA Technical Reports Server (NTRS)

Dunn, C. E.; Lichten, S. M.; Jefferson, D. C.; Border, J. S.

1992-01-01

Interferometric spacecraft tracking is accomplished by the Deep Space Network (DSN) by comparing the arrival time of electromagnetic spacecraft signals at ground antennas separated by baselines on the order of 8000 km. Clock synchronization errors within and between DSN stations directly impact the attainable tracking accuracy, with a 0.3-nsec error in clock synchronization resulting in an 11-nrad angular position error. This level of synchronization is currently achieved by observing a quasar which is angularly close to the spacecraft just after the spacecraft observations. By determining the differential arrival times of the random quasar signal at the stations, clock offsets and propagation delays within the atmosphere and within the DSN stations are calibrated. Recent developments in time transfer techniques may allow medium accuracy (50-100 nrad) spacecraft tracking without near-simultaneous quasar-based calibrations. Solutions are presented for a worldwide network of Global Positioning System (GPS) receivers in which the formal errors for DSN clock offset parameters are less than 0.5 nsec. Comparisons of clock rate offsets derived from GPS measurements and from very long baseline interferometry (VLBI), as well as the examination of clock closure, suggest that these formal errors are a realistic measure of GPS-based clock offset precision and accuracy. Incorporating GPS-based clock synchronization measurements into a spacecraft differential ranging system would allow tracking without near-simultaneous quasar observations. The impact on individual spacecraft navigation-error sources due to elimination of quasar-based calibrations is presented. System implementation, including calibration of station electronic delays, is discussed.

Ion track etching revisited: I. Correlations between track parameters in aged polymers

NASA Astrophysics Data System (ADS)

Fink, D.; Muñoz H., G.; García A., H.; Vacik, J.; Hnatowicz, V.; Kiv, A.; Alfonta, L.

2018-04-01

Some yet poorly understood problems of etching of pristine and swift heavy ion track-irradiated aged polymers were treated, by applying conductometry across the irradiated foils during etching. The onset times of etchant penetration across pristine foils, and the onset times of the different etched track regimes in irradiated foils were determined for polymers of various proveniences, fluences and ages, as well as their corresponding etching speeds. From the results, correlations of the parameters with each other were deduced. The normalization of these parameters enables one to compare irradiated polymer foils of different origin and treatment with one another. In a number of cases, also polymeric gel formation and swelling occur which influence the track etching behaviour. The polymer degradation during aging influences the track etching parameters, which differ from each other on both sides of the foils. With increasing sample age, these differences increase.

Interface of the general fitting tool GENFIT2 in PandaRoot

NASA Astrophysics Data System (ADS)

Prencipe, Elisabetta; Spataro, Stefano; Stockmanns, Tobias; PANDA Collaboration

2017-10-01

\\bar{{{P}}}ANDA is a planned experiment at FAIR (Darmstadt) with a cooled antiproton beam in a range [1.5; 15] GeV/c, allowing a wide physics program in nuclear and particle physics. It is the only experiment worldwide, which combines a solenoid field (B=2T) and a dipole field (B=2Tm) in a spectrometer with a fixed target topology, in that energy regime. The tracking system of \\bar{{{P}}}ANDA involves the presence of a high performance silicon vertex detector, a GEM detector, a straw-tubes central tracker, a forward tracking system, and a luminosity monitor. The offline tracking algorithm is developed within the PandaRoot framework, which is a part of the FairRoot project. The tool here presented is based on algorithms containing the Kalman Filter equations and a deterministic annealing filter. This general fitting tool (GENFIT2) offers to users also a Runge-Kutta track representation, and interfaces with Millepede II (useful for alignment) and RAVE (vertex finder). It is independent on the detector geometry and the magnetic field map, and written in C++ object-oriented modular code. Several fitting algorithms are available with GENFIT2, with user-adjustable parameters; therefore the tool is of friendly usage. A check on the fit convergence is done by GENFIT2 as well. The Kalman-Filter-based algorithms have a wide range of applications; among those in particle physics they can perform extrapolations of track parameters and covariance matrices. The adoptions of the PandaRoot framework to connect to Genfit2 are described, and the impact of GENFIT2 on the physics simulations of \\bar{{{P}}}ANDA are shown: significant improvement is reported for those channels where a good low momentum tracking is required (pT < 400 MeV/c).

Effect of Preload Alterations on Left Ventricular Systolic Parameters Including Speckle-Tracking Echocardiography Radial Strain During General Anesthesia.

PubMed

Weber, Ulrike; Base, Eva; Ristl, Robin; Mora, Bruno

2015-08-01

Frequently used parameters for evaluation of left ventricular systolic function are load-sensitive. However, the impact of preload alterations on speckle-tracking echocardiographic parameters during anesthesia has not been validated. Therefore, two-dimensional (2D) speckle-tracking echocardiography radial strain (RS) was assessed during general anesthesia, simulating 3 different preload conditions. Single-center prospective observational study. University hospital. Thirty-three patients with normal left ventricular systolic function undergoing major surgery. Transgastric views of the midpapillary level of the left ventricle were acquired at 3 different positions. Fractional shortening (FS), fractional area change (FAC), and 2D speckle-tracking echocardiography RS were analyzed in the transgastric midpapillary view. Considerable correlation above 0.5 was found for FAC and FS in the zero and Trendelenburg positions (r = 0.629, r = 0.587), and for RS and FAC in the anti-Trendelenburg position (r = 0.518). In the repeated-measures analysis, significant differences among the values measured at the 3 positions were found for FAC and FS. For FAC, there were differences up to 2.8 percentage points between the anti-Trendelenburg position and the other 2 positions. For FS, only the difference between position zero and anti-Trendelenburg was significant, with an observed change of 1.66. Two-dimensional RS was not significantly different at all positions, with observed changes below 1 percentage point. Alterations in preload did not result in clinically relevant changes of RS, FS, or FAC. Observed changes for RS were smallest; however, the variation of RS was larger than that of FS or FAC. Copyright © 2015 Elsevier Inc. All rights reserved.

Reopening abandoned forest roads in northern Idaho, USA: quantification of runoff, sediment concentration, infiltration, and interrill erosion parameters.

PubMed

Foltz, R B; Copeland, N S; Elliot, W J

2009-06-01

This study measured runoff and sediment concentration from the tire track and from the non-tire track to determine infiltration, interrill erodibility, and vegetative cover impacts of reopening an abandoned forest road. Runoff was lowest on the non-track portion of the abandoned road and highest on the reopened road. Sediment concentrations were significantly higher on the reopened road. Increased sediment concentrations were attributed to decreased vegetative cover, rather than traffic-induced changes in the physical soil properties of the reopened road. Thirty years of no traffic and vegetation regrowth was not sufficient to allow recovery of infiltration to values similar to an undisturbed forest. The study also found a significant dynamic behavior in interrill erodibility with respect to antecedent rainfall. Forest road erosion models that fail to account for this change will overestimate sediment yields.

Precise interferometric tracking of the DSCS II geosynchronous orbiter

NASA Astrophysics Data System (ADS)

Border, J. S.; Donivan, F. F., Jr.; Shiomi, T.; Kawano, N.

1986-01-01

A demonstration of the precise tracking of a geosynchronous orbiter by radio metric techniques based on very-long-baseline interferometry (VLBI) has been jointly conducted by the Jet Propulsion Laboratory and Japan's Radio Research Laboratory. Simultaneous observations of a U.S. Air Force communications satellite from tracking stations in California, Australia, and Japan have determined the satellite's position with an accuracy of a few meters. Accuracy claims are based on formal statistics, which include the effects of errors in non-estimated parameters and which are supported by a chi-squared of less than one, and on the consistency of orbit solutions from disjoint data sets. A study made to assess the impact of shorter baselines and reduced data noise concludes that with a properly designed system, similar accuracy could be obtained for either a satellite viewed from stations located within the continental U.S. or for a satellite viewed from stations within Japanese territory.

A dynamic wheel-rail impact analysis of railway track under wheel flat by finite element analysis

NASA Astrophysics Data System (ADS)

Bian, Jian; Gu, Yuantong; Murray, Martin Howard

2013-06-01

Wheel-rail interaction is one of the most important research topics in railway engineering. It involves track impact response, track vibration and track safety. Track structure failures caused by wheel-rail impact forces can lead to significant economic loss for track owners through damage to rails and to the sleepers beneath. Wheel-rail impact forces occur because of imperfections in the wheels or rails such as wheel flats, irregular wheel profiles, rail corrugations and differences in the heights of rails connected at a welded joint. A wheel flat can cause a large dynamic impact force as well as a forced vibration with a high frequency, which can cause damage to the track structure. In the present work, a three-dimensional finite element (FE) model for the impact analysis induced by the wheel flat is developed by the use of the FE analysis (FEA) software package ANSYS and validated by another validated simulation. The effect of wheel flats on impact forces is thoroughly investigated. It is found that the presence of a wheel flat will significantly increase the dynamic impact force on both rail and sleeper. The impact force will monotonically increase with the size of wheel flats. The relationships between the impact force and the wheel flat size are explored from this FEA and they are important for track engineers to improve their understanding of the design and maintenance of the track system.

Adaptive Parameter Estimation of Person Recognition Model in a Stochastic Human Tracking Process

NASA Astrophysics Data System (ADS)

Nakanishi, W.; Fuse, T.; Ishikawa, T.

2015-05-01

This paper aims at an estimation of parameters of person recognition models using a sequential Bayesian filtering method. In many human tracking method, any parameters of models used for recognize the same person in successive frames are usually set in advance of human tracking process. In real situation these parameters may change according to situation of observation and difficulty level of human position prediction. Thus in this paper we formulate an adaptive parameter estimation using general state space model. Firstly we explain the way to formulate human tracking in general state space model with their components. Then referring to previous researches, we use Bhattacharyya coefficient to formulate observation model of general state space model, which is corresponding to person recognition model. The observation model in this paper is a function of Bhattacharyya coefficient with one unknown parameter. At last we sequentially estimate this parameter in real dataset with some settings. Results showed that sequential parameter estimation was succeeded and were consistent with observation situations such as occlusions.

Computer program TRACK_TEST for calculating parameters and plotting profiles for etch pits in nuclear track materials

NASA Astrophysics Data System (ADS)

Nikezic, D.; Yu, K. N.

2006-01-01

A computer program called TRACK_TEST for calculating parameters (lengths of the major and minor axes) and plotting profiles in nuclear track materials resulted from light-ion irradiation and subsequent chemical etching is described. The programming steps are outlined, including calculations of alpha-particle ranges, determination of the distance along the particle trajectory penetrated by the chemical etchant, calculations of track coordinates, determination of the lengths of the major and minor axes and determination of the contour of the track opening. Descriptions of the program are given, including the built-in V functions for the two commonly employed nuclear track materials commercially known as LR 115 (cellulose nitrate) and CR-39 (poly allyl diglycol carbonate) irradiated by alpha particles. Program summaryTitle of the program:TRACK_TEST Catalogue identifier:ADWT Program obtainable from:CPC Program Library, Queen's University of Belfast, N. Ireland Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWT Computer:Pentium PC Operating systems:Windows 95+ Programming language:Fortran 90 Memory required to execute with typical data:256 MB No. of lines in distributed program, including test data, etc.: 2739 No. of bytes in distributed program, including test data, etc.:204 526 Distribution format:tar.gz External subprograms used:The entire code must be linked with the MSFLIB library Nature of problem: Fast heavy charged particles (like alpha particles and other light ions etc.) create latent tracks in some dielectric materials. After chemical etching in aqueous NaOH or KOH solutions, these tracks become visible under an optical microscope. The growth of a track is based on the simultaneous actions of the etchant on undamaged regions (with the bulk etch rate V) and along the particle track (with the track etch rate V). Growth of the track is described satisfactorily by these two parameters ( V and V). Several models have been presented in the past describing the track development, one of which is the model of Nikezic and Yu (2003) [D. Nikezic, K.N. Yu, Three-dimensional analytical determination of the track parameters. Over-etched tracks, Radiat. Meas. 37 (2003) 39-45] used in the present program. The present computer program has been written to calculate coordinates of points on the track wall and to determine other relevant track parameters. Solution method:Coordinates of points on the track wall assuming normal incidence were calculated by using the method as described by Fromm et al. (1988) [M. Fromm, A. Chambaudet, F. Membrey, Data bank for alpha particle tracks in CR39 with energies ranging from 0.5 to 5 MeV recording for various incident angles, Nucl. Tracks Radiat. Meas. 15 (1988) 115-118]. The track is then rotated through the incident angle in order to obtain the coordinates of the oblique track [D. Nikezic, K.N. Yu, Three-dimensional analytical determination of the track parameters. Over-etched tracks, Radiat. Meas. 37 (2003) 39-45; D. Nikezic, Three dimensional analytical determination of the track parameters, Radiat. Meas. 32 (2000) 277-282]. In this way, the track profile in two dimensions (2D) was obtained. In the next step, points in the track wall profile are rotated around the particle trajectory. In this way, circles that outline the track in three dimensions (3D) are obtained. The intersection between the post-etching surface of the detector and the 3D track is the track opening (or the track contour). Coordinates of the track 2D and 3D profiles and the track opening are saved in separate output data files. Restrictions: The program cannot calculate track parameters for the incident angle of exactly 90°. The alpha-particle energy should be smaller than 10 MeV. Furthermore, the program cannot perform calculations for tracks in some extreme cases, such as for very low incident energies or very small incident angles. Additional comments: This is a freeware, but publications arising from using this program should cite the present paper and the paper describing the track growth model [D. Nikezic, K.N. Yu, Three-dimensional analytical determination of the track parameters. Over-etched tracks, Radiat. Meas. 37 (2003) 39-45]. Moreover, the references for the V functions used should also be cited. For the CR-39 detector: Function (1): S.A. Durrani, R.K. Bull, Solid State Nuclear Track Detection. Principles, Methods and Applications, Pergamon Press, 1987. Function (2): C. Brun, M. Fromm, M. Jouffroy, P. Meyer, J.E. Groetz, F. Abel, A. Chambaudet, B. Dorschel, D. Hermsdorf, R. Bretschneider, K. Kadner, H. Kuhne, Intercomparative study of the detection characteristics of the CR-39 SSNTD for light ions: Present status of the Besancon-Dresden approaches, Radiat. Meas. 31 (1999) 89-98. Function (3): K.N. Yu, F.M.F. Ng, D. Nikezic, Measuring depths of sub-micron tracks in a CR-39 detector from replicas using atomic force microscopy, Radiat. Meas. 40 (2005) 380-383. For the LR 115 detector: Function (1): S.A. Durrani, P.F. Green, The effect of etching conditions on the response of LR 115, Nucl. Tracks 8 (1984) 21-24. Function (2): C.W.Y. Yip, D. Nikezic, J.P.Y Ho, K.N. Yu, Chemical etching characteristics for cellulose nitrate, Mat. Chem. Phys. 95 (2005) 307-312. Running time: Order of several minutes, dependent on input parameters and the resolution requested by the user.

Assimilation of Tropical Cyclone Track and Wind Radius Data with an Ensemble Kalman Filter

NASA Astrophysics Data System (ADS)

Kunii, M.

2014-12-01

Improving tropical cyclone (TC) forecasts is one of the most important issues in meteorology, but TC intensity forecasts are a challenging task. Because the lack of observations near TCs usually results in degraded accuracy of initial fields, utilizing TC advisory data in data assimilation typically has started with an ensemble Kalman filtering (EnKF). In this study, TC intensity and position information was directly assimilated using the EnKF, and the impact of these observations was investigated by comparing different assimilation strategies. Another experiment with TC wind radius data was carried out to examine the influence of TC shape parameters. Sensitivity experiments indicated that the assimilation of TC intensity and position data yielded results that were superior to those based on conventional assimilation of TC minimum sea level pressure as a standard surface pressure observation. Assimilation of TC radius data modified TC outer circulations closer to observations. The impacts of these TC parameters were also evaluated using the case of Typhoon Talas in 2011. The TC intensity, position, and wind radius data led to improved TC track forecasts and thence to improved precipitation forecasts. These results imply that initialization with these TC-related observations benefits TC forecasts, offering promise for the prevention and mitigation of natural disasters caused by TCs.

Design of state-feedback controllers including sensitivity reduction, with applications to precision pointing

NASA Technical Reports Server (NTRS)

Hadass, Z.

1974-01-01

The design procedure of feedback controllers was described and the considerations for the selection of the design parameters were given. The frequency domain properties of single-input single-output systems using state feedback controllers are analyzed, and desirable phase and gain margin properties are demonstrated. Special consideration is given to the design of controllers for tracking systems, especially those designed to track polynomial commands. As an example, a controller was designed for a tracking telescope with a polynomial tracking requirement and some special features such as actuator saturation and multiple measurements, one of which is sampled. The resulting system has a tracking performance comparing favorably with a much more complicated digital aided tracker. The parameter sensitivity reduction was treated by considering the variable parameters as random variables. A performance index is defined as a weighted sum of the state and control convariances that sum from both the random system disturbances and the parameter uncertainties, and is minimized numerically by adjusting a set of free parameters.

Bayesian source tracking via focalization and marginalization in an uncertain Mediterranean Sea environment.

PubMed

Dosso, Stan E; Wilmut, Michael J; Nielsen, Peter L

2010-07-01

This paper applies Bayesian source tracking in an uncertain environment to Mediterranean Sea data, and investigates the resulting tracks and track uncertainties as a function of data information content (number of data time-segments, number of frequencies, and signal-to-noise ratio) and of prior information (environmental uncertainties and source-velocity constraints). To track low-level sources, acoustic data recorded for multiple time segments (corresponding to multiple source positions along the track) are inverted simultaneously. Environmental uncertainty is addressed by including unknown water-column and seabed properties as nuisance parameters in an augmented inversion. Two approaches are considered: Focalization-tracking maximizes the posterior probability density (PPD) over the unknown source and environmental parameters. Marginalization-tracking integrates the PPD over environmental parameters to obtain a sequence of joint marginal probability distributions over source coordinates, from which the most-probable track and track uncertainties can be extracted. Both approaches apply track constraints on the maximum allowable vertical and radial source velocity. The two approaches are applied for towed-source acoustic data recorded at a vertical line array at a shallow-water test site in the Mediterranean Sea where previous geoacoustic studies have been carried out.

Comparison of different detection methods for persistent multiple hypothesis tracking in wide area motion imagery

NASA Astrophysics Data System (ADS)

Hartung, Christine; Spraul, Raphael; Schuchert, Tobias

2017-10-01

Wide area motion imagery (WAMI) acquired by an airborne multicamera sensor enables continuous monitoring of large urban areas. Each image can cover regions of several square kilometers and contain thousands of vehicles. Reliable vehicle tracking in this imagery is an important prerequisite for surveillance tasks, but remains challenging due to low frame rate and small object size. Most WAMI tracking approaches rely on moving object detections generated by frame differencing or background subtraction. These detection methods fail when objects slow down or stop. Recent approaches for persistent tracking compensate for missing motion detections by combining a detection-based tracker with a second tracker based on appearance or local context. In order to avoid the additional complexity introduced by combining two trackers, we employ an alternative single tracker framework that is based on multiple hypothesis tracking and recovers missing motion detections with a classifierbased detector. We integrate an appearance-based similarity measure, merge handling, vehicle-collision tests, and clutter handling to adapt the approach to the specific context of WAMI tracking. We apply the tracking framework on a region of interest of the publicly available WPAFB 2009 dataset for quantitative evaluation; a comparison to other persistent WAMI trackers demonstrates state of the art performance of the proposed approach. Furthermore, we analyze in detail the impact of different object detection methods and detector settings on the quality of the output tracking results. For this purpose, we choose four different motion-based detection methods that vary in detection performance and computation time to generate the input detections. As detector parameters can be adjusted to achieve different precision and recall performance, we combine each detection method with different detector settings that yield (1) high precision and low recall, (2) high recall and low precision, and (3) best f-score. Comparing the tracking performance achieved with all generated sets of input detections allows us to quantify the sensitivity of the tracker to different types of detector errors and to derive recommendations for detector and parameter choice.

Dynamic modeling, property investigation, and adaptive controller design of serial robotic manipulators modeled with structural compliance

NASA Technical Reports Server (NTRS)

Tesar, Delbert; Tosunoglu, Sabri; Lin, Shyng-Her

1990-01-01

Research results on general serial robotic manipulators modeled with structural compliances are presented. Two compliant manipulator modeling approaches, distributed and lumped parameter models, are used in this study. System dynamic equations for both compliant models are derived by using the first and second order influence coefficients. Also, the properties of compliant manipulator system dynamics are investigated. One of the properties, which is defined as inaccessibility of vibratory modes, is shown to display a distinct character associated with compliant manipulators. This property indicates the impact of robot geometry on the control of structural oscillations. Example studies are provided to illustrate the physical interpretation of inaccessibility of vibratory modes. Two types of controllers are designed for compliant manipulators modeled by either lumped or distributed parameter techniques. In order to maintain the generality of the results, neither linearization is introduced. Example simulations are given to demonstrate the controller performance. The second type controller is also built for general serial robot arms and is adaptive in nature which can estimate uncertain payload parameters on-line and simultaneously maintain trajectory tracking properties. The relation between manipulator motion tracking capability and convergence of parameter estimation properties is discussed through example case studies. The effect of control input update delays on adaptive controller performance is also studied.

Muon Energy Calibration of the MINOS Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyagawa, Paul S.

MINOS is a long-baseline neutrino oscillation experiment designed to search for conclusive evidence of neutrino oscillations and to measure the oscillation parameters precisely. MINOS comprises two iron tracking calorimeters located at Fermilab and Soudan. The Calibration Detector at CERN is a third MINOS detector used as part of the detector response calibration programme. A correct energy calibration between these detectors is crucial for the accurate measurement of oscillation parameters. This thesis presents a calibration developed to produce a uniform response within a detector using cosmic muons. Reconstruction of tracks in cosmic ray data is discussed. This data is utilized tomore » calculate calibration constants for each readout channel of the Calibration Detector. These constants have an average statistical error of 1.8%. The consistency of the constants is demonstrated both within a single run and between runs separated by a few days. Results are presented from applying the calibration to test beam particles measured by the Calibration Detector. The responses are calibrated to within 1.8% systematic error. The potential impact of the calibration on the measurement of oscillation parameters by MINOS is also investigated. Applying the calibration reduces the errors in the measured parameters by ~ 10%, which is equivalent to increasing the amount of data by 20%.« less

Ground Data System Analysis Tools to Track Flight System State Parameters for the Mars Science Laboratory (MSL) and Beyond

NASA Technical Reports Server (NTRS)

Allard, Dan; Deforrest, Lloyd

2014-01-01

Flight software parameters enable space mission operators fine-tuned control over flight system configurations, enabling rapid and dynamic changes to ongoing science activities in a much more flexible manner than can be accomplished with (otherwise broadly used) configuration file based approaches. The Mars Science Laboratory (MSL), Curiosity, makes extensive use of parameters to support complex, daily activities via commanded changes to said parameters in memory. However, as the loss of Mars Global Surveyor (MGS) in 2006 demonstrated, flight system management by parameters brings with it risks, including the possibility of losing track of the flight system configuration and the threat of invalid command executions. To mitigate this risk a growing number of missions have funded efforts to implement parameter tracking parameter state software tools and services including MSL and the Soil Moisture Active Passive (SMAP) mission. This paper will discuss the engineering challenges and resulting software architecture of MSL's onboard parameter state tracking software and discuss the road forward to make parameter management tools suitable for use on multiple missions.

On the consistency among different approaches for nuclear track scanning and data processing

NASA Astrophysics Data System (ADS)

Inozemtsev, K. O.; Kushin, V. V.; Kodaira, S.; Shurshakov, V. A.

2018-04-01

The article describes various approaches for space radiation track measurement using CR-39™ detector (Tastrak). The results of comparing different methods for track scanning and data processing are presented. Basic algorithms for determination of track parameters are described. Every approach involves individual set of measured track parameters. For two sets, track scanning is sufficient in the plane of detector surface (2-D measurement), third set requires scanning in the additional projection (3-D measurement). An experimental comparison of considered techniques was made with the use of accelerated heavy ions Ar, Fe and Kr.

The Impact of the Geometrical Structure of the DNA on Parameters of the Track-Event Theory for Radiation Induced Cell Kill.

PubMed

Schneider, Uwe; Vasi, Fabiano; Besserer, Jürgen

2016-01-01

When fractionation schemes for hypofractionation and stereotactic body radiotherapy are considered, a reliable cell survival model at high dose is needed for calculating doses of similar biological effectiveness. An alternative to the LQ-model is the track-event theory which is based on the probabilities for one- and two two-track events. A one-track-event (OTE) is always represented by at least two simultaneous double strand breaks. A two-track-event (TTE) results in one double strand break. Therefore at least two two-track-events on the same or different chromosomes are necessary to produce an event which leads to cell sterilization. It is obvious that the probabilities of OTEs and TTEs must somehow depend on the geometrical structure of the chromatin. In terms of the track-event theory the ratio ε of the probabilities of OTEs and TTEs includes the geometrical dependence and is obtained in this work by simple Monte Carlo simulations. For this work it was assumed that the anchors of loop forming chromatin are most sensitive to radiation induced cell deaths. Therefore two adjacent tetranucleosomes representing the loop anchors were digitized. The probability ratio ε of OTEs and TTEs was factorized into a radiation quality dependent part and a geometrical part: ε = εion ∙ εgeo. εgeo was obtained for two situations, by applying Monte Carlo simulation for DNA on the tetranucleosomes itself and for linker DNA. Low energy electrons were represented by randomly distributed ionizations and high energy electrons by ionizations which were simulated on rays. εion was determined for electrons by using results from nanodosimetric measurements. The calculated ε was compared to the ε obtained from fits of the track event model to 42 sets of experimental human cell survival data. When the two tetranucleosomes are in direct contact and the hits are randomly distributed εgeo and ε are 0.12 and 0.85, respectively. When the hits are simulated on rays εgeo and ε are 0.10 and 0.71. For the linker-DNA εgeo and ε for randomly distributed hits are 0.010 and 0.073, and for hits on rays 0.0058 and 0.041, respectively. The calculated ε fits the experimentally obtained ε = 0.64±0.32 best for hits on the tetranucleosome when they are close to each other both, for high and low energy electrons. The parameter εgeo of the track event model was obtained by pure geometrical considerations of the chromatin structure and is 0.095 ± 0.022. It can be used as a fixed parameter in the track-event theory.

Characterization of Factors Affecting Nanoparticle Tracking Analysis Results With Synthetic and Protein Nanoparticles.

PubMed

Krueger, Aaron B; Carnell, Pauline; Carpenter, John F

2016-04-01

In many manufacturing and research areas, the ability to accurately monitor and characterize nanoparticles is becoming increasingly important. Nanoparticle tracking analysis is rapidly becoming a standard method for this characterization, yet several key factors in data acquisition and analysis may affect results. Nanoparticle tracking analysis is prone to user input and bias on account of a high number of parameters available, contains a limited analysis volume, and individual sample characteristics such as polydispersity or complex protein solutions may affect analysis results. This study systematically addressed these key issues. The integrated syringe pump was used to increase the sample volume analyzed. It was observed that measurements recorded under flow caused a reduction in total particle counts for both polystyrene and protein particles compared to those collected under static conditions. In addition, data for polydisperse samples tended to lose peak resolution at higher flow rates, masking distinct particle populations. Furthermore, in a bimodal particle population, a bias was seen toward the larger species within the sample. The impacts of filtration on an agitated intravenous immunoglobulin sample and operating parameters including "MINexps" and "blur" were investigated to optimize the method. Taken together, this study provides recommendations on instrument settings and sample preparations to properly characterize complex samples. Copyright © 2016. Published by Elsevier Inc.

Development and testing of a magnetic position sensor system for automotive and avionics applications

NASA Astrophysics Data System (ADS)

Jacobs, Bryan C.; Nelson, Carl V.

2001-08-01

A magnetic sensor system has been developed to measure the 3-D location and orientation of a rigid body relative to an array of magnetic dipole transmitters. A generalized solution to the measurement problem has been formulated, allowing the transmitter and receiver parameters (position, orientation, number, etc.) to be optimized for various applications. Additionally, the method of images has been used to mitigate the impact of metallic materials in close proximity to the sensor. The resulting system allows precise tracking of high-speed motion in confined metal environments. The sensor system was recently configured and tested as an abdomen displacement sensor for an automobile crash-test dummy. The test results indicate a positional accuracy of approximately 1 mm rms during 20 m/s motions. The dynamic test results also confirmed earlier covariance model predictions, which were used to optimize the sensor geometry. A covariance analysis was performed to evaluate the applicability of this magnetic position system for tracking a pilot's head motion inside an aircraft cockpit. Realistic design parameters indicate that a robust tracking system, consisting of lightweight pickup coils mounted on a pilot's helmet, and an array of transmitter coils distributed throughout a cockpit, is feasible. Recent test and covariance results are presented.

An efficient approach to the analysis of rail surface irregularities accounting for dynamic train-track interaction and inelastic deformations

NASA Astrophysics Data System (ADS)

Andersson, Robin; Torstensson, Peter T.; Kabo, Elena; Larsson, Fredrik

2015-11-01

A two-dimensional computational model for assessment of rolling contact fatigue induced by discrete rail surface irregularities, especially in the context of so-called squats, is presented. Dynamic excitation in a wide frequency range is considered in computationally efficient time-domain simulations of high-frequency dynamic vehicle-track interaction accounting for transient non-Hertzian wheel-rail contact. Results from dynamic simulations are mapped onto a finite element model to resolve the cyclic, elastoplastic stress response in the rail. Ratcheting under multiple wheel passages is quantified. In addition, low cycle fatigue impact is quantified using the Jiang-Sehitoglu fatigue parameter. The functionality of the model is demonstrated by numerical examples.

Distributed Time-Varying Formation Robust Tracking for General Linear Multiagent Systems With Parameter Uncertainties and External Disturbances.

PubMed

Hua, Yongzhao; Dong, Xiwang; Li, Qingdong; Ren, Zhang

2017-05-18

This paper investigates the time-varying formation robust tracking problems for high-order linear multiagent systems with a leader of unknown control input in the presence of heterogeneous parameter uncertainties and external disturbances. The followers need to accomplish an expected time-varying formation in the state space and track the state trajectory produced by the leader simultaneously. First, a time-varying formation robust tracking protocol with a totally distributed form is proposed utilizing the neighborhood state information. With the adaptive updating mechanism, neither any global knowledge about the communication topology nor the upper bounds of the parameter uncertainties, external disturbances and leader's unknown input are required in the proposed protocol. Then, in order to determine the control parameters, an algorithm with four steps is presented, where feasible conditions for the followers to accomplish the expected time-varying formation tracking are provided. Furthermore, based on the Lyapunov-like analysis theory, it is proved that the formation tracking error can converge to zero asymptotically. Finally, the effectiveness of the theoretical results is verified by simulation examples.

A Bayesian approach to tracking patients having changing pharmacokinetic parameters

NASA Technical Reports Server (NTRS)

Bayard, David S.; Jelliffe, Roger W.

2004-01-01

This paper considers the updating of Bayesian posterior densities for pharmacokinetic models associated with patients having changing parameter values. For estimation purposes it is proposed to use the Interacting Multiple Model (IMM) estimation algorithm, which is currently a popular algorithm in the aerospace community for tracking maneuvering targets. The IMM algorithm is described, and compared to the multiple model (MM) and Maximum A-Posteriori (MAP) Bayesian estimation methods, which are presently used for posterior updating when pharmacokinetic parameters do not change. Both the MM and MAP Bayesian estimation methods are used in their sequential forms, to facilitate tracking of changing parameters. Results indicate that the IMM algorithm is well suited for tracking time-varying pharmacokinetic parameters in acutely ill and unstable patients, incurring only about half of the integrated error compared to the sequential MM and MAP methods on the same example.

Tape tracking and handling for magnetic tape recorders. [aboard spacecraft

NASA Technical Reports Server (NTRS)

Paroby, W.; Disilvestre, R.

1975-01-01

One of the critical performance and life limiting elements of a spacecraft tape recorder instrumentation system which has received little attention in technical literature is magnetic tape tracking and handling technology. This technology is required to understand how to gently transfer tape from one reel to another with proper alignment and a desirable uniform velocity at the read and write transducer heads. The increased demand for high data rate (i.e., multi-track spacecraft recording instrumentation systems), coupled with performance under extreme environmental conditions, requires a thorough knowledge of the various parameters which establish an optimum designed tape tracking and handling system. Stress analysis techniques are required to evaluate these parameters substantiated with test tape tracking data, to show the effect of each parameter on a tape recorder instrumentation tracking system. The technology is applicable to ground type tape recorders where the detrimental effects of edge guidance can be eliminated.

Extrapolating target tracks

NASA Astrophysics Data System (ADS)

Van Zandt, James R.

2012-05-01

Steady-state performance of a tracking filter is traditionally evaluated immediately after a track update. However, there is commonly a further delay (e.g., processing and communications latency) before the tracks can actually be used. We analyze the accuracy of extrapolated target tracks for four tracking filters: Kalman filter with the Singer maneuver model and worst-case correlation time, with piecewise constant white acceleration, and with continuous white acceleration, and the reduced state filter proposed by Mookerjee and Reifler.1, 2 Performance evaluation of a tracking filter is significantly simplified by appropriate normalization. For the Kalman filter with the Singer maneuver model, the steady-state RMS error immediately after an update depends on only two dimensionless parameters.3 By assuming a worst case value of target acceleration correlation time, we reduce this to a single parameter without significantly changing the filter performance (within a few percent for air tracking).4 With this simplification, we find for all four filters that the RMS errors for the extrapolated state are functions of only two dimensionless parameters. We provide simple analytic approximations in each case.

Optimal Control Method of Robot End Position and Orientation Based on Dynamic Tracking Measurement

NASA Astrophysics Data System (ADS)

Liu, Dalong; Xu, Lijuan

2018-01-01

In order to improve the accuracy of robot pose positioning and control, this paper proposed a dynamic tracking measurement robot pose optimization control method based on the actual measurement of D-H parameters of the robot, the parameters is taken with feedback compensation of the robot, according to the geometrical parameters obtained by robot pose tracking measurement, improved multi sensor information fusion the extended Kalan filter method, with continuous self-optimal regression, using the geometric relationship between joint axes for kinematic parameters in the model, link model parameters obtained can timely feedback to the robot, the implementation of parameter correction and compensation, finally we can get the optimal attitude angle, realize the robot pose optimization control experiments were performed. 6R dynamic tracking control of robot joint robot with independent research and development is taken as experimental subject, the simulation results show that the control method improves robot positioning accuracy, and it has the advantages of versatility, simplicity, ease of operation and so on.

Peak impact accelerations during track and treadmill running.

PubMed

Bigelow, Erin M R; Elvin, Niell G; Elvin, Alex A; Arnoczky, Steven P

2013-10-01

To determine whether peak vertical and horizontal impact accelerations were different while running on a track or on a treadmill, 12 healthy subjects (average age 32.8 ± 9.8 y), were fitted with a novel, wireless accelerometer capable of recording triaxial acceleration over time. The accelerometer was attached to a custom-made acrylic plate and secured at the level of the L5 vertebra via a tight fitting triathlon belt. Each subject ran 4 miles on a synthetic, indoor track at a self-selected pace and accelerations were recorded on three perpendicular axes. Seven days later, the subjects ran 4 miles on a treadmill set at the individual runner's average pace on the track and the peak vertical and horizontal impact magnitudes between the track and treadmill were compared. There was no difference (P = .52) in the average peak vertical impact accelerations between the track and treadmill over the 4 mile run. However, peak horizontal impact accelerations were greater (P = .0012) on the track when compared with the treadmill. This study demonstrated the feasibility for long-term impact accelerations monitoring using a novel wireless accelerometer.

Robust adaptive uniform exact tracking control for uncertain Euler-Lagrange system

NASA Astrophysics Data System (ADS)

Yang, Yana; Hua, Changchun; Li, Junpeng; Guan, Xinping

2017-12-01

This paper offers a solution to the robust adaptive uniform exact tracking control for uncertain nonlinear Euler-Lagrange (EL) system. An adaptive finite-time tracking control algorithm is designed by proposing a novel nonsingular integral terminal sliding-mode surface. Moreover, a new adaptive parameter tuning law is also developed by making good use of the system tracking errors and the adaptive parameter estimation errors. Thus, both the trajectory tracking and the parameter estimation can be achieved in a guaranteed time adjusted arbitrarily based on practical demands, simultaneously. Additionally, the control result for the EL system proposed in this paper can be extended to high-order nonlinear systems easily. Finally, a test-bed 2-DOF robot arm is set-up to demonstrate the performance of the new control algorithm.

Sub-nanosecond clock synchronization and precision deep space tracking

NASA Technical Reports Server (NTRS)

Dunn, Charles; Lichten, Stephen; Jefferson, David; Border, James S.

1992-01-01

Interferometric spacecraft tracking is accomplished at the NASA Deep Space Network (DSN) by comparing the arrival time of electromagnetic spacecraft signals to ground antennas separated by baselines on the order of 8000 km. Clock synchronization errors within and between DSN stations directly impact the attainable tracking accuracy, with a 0.3 ns error in clock synchronization resulting in an 11 nrad angular position error. This level of synchronization is currently achieved by observing a quasar which is angularly close to the spacecraft just after the spacecraft observations. By determining the differential arrival times of the random quasar signal at the stations, clock synchronization and propagation delays within the atmosphere and within the DSN stations are calibrated. Recent developments in time transfer techniques may allow medium accuracy (50-100 nrad) spacecraft observations without near-simultaneous quasar-based calibrations. Solutions are presented for a global network of GPS receivers in which the formal errors in clock offset parameters are less than 0.5 ns. Comparisons of clock rate offsets derived from GPS measurements and from very long baseline interferometry and the examination of clock closure suggest that these formal errors are a realistic measure of GPS-based clock offset precision and accuracy. Incorporating GPS-based clock synchronization measurements into a spacecraft differential ranging system would allow tracking without near-simultaneous quasar observations. The impact on individual spacecraft navigation error sources due to elimination of quasar-based calibrations is presented. System implementation, including calibration of station electronic delays, is discussed.

Perceptual control models of pursuit manual tracking demonstrate individual specificity and parameter consistency.

PubMed

Parker, Maximilian G; Tyson, Sarah F; Weightman, Andrew P; Abbott, Bruce; Emsley, Richard; Mansell, Warren

2017-11-01

Computational models that simulate individuals' movements in pursuit-tracking tasks have been used to elucidate mechanisms of human motor control. Whilst there is evidence that individuals demonstrate idiosyncratic control-tracking strategies, it remains unclear whether models can be sensitive to these idiosyncrasies. Perceptual control theory (PCT) provides a unique model architecture with an internally set reference value parameter, and can be optimized to fit an individual's tracking behavior. The current study investigated whether PCT models could show temporal stability and individual specificity over time. Twenty adults completed three blocks of 15 1-min, pursuit-tracking trials. Two blocks (training and post-training) were completed in one session and the third was completed after 1 week (follow-up). The target moved in a one-dimensional, pseudorandom pattern. PCT models were optimized to the training data using a least-mean-squares algorithm, and validated with data from post-training and follow-up. We found significant inter-individual variability (partial η 2 : .464-.697) and intra-individual consistency (Cronbach's α: .880-.976) in parameter estimates. Polynomial regression revealed that all model parameters, including the reference value parameter, contribute to simulation accuracy. Participants' tracking performances were significantly more accurately simulated by models developed from their own tracking data than by models developed from other participants' data. We conclude that PCT models can be optimized to simulate the performance of an individual and that the test-retest reliability of individual models is a necessary criterion for evaluating computational models of human performance.

Application of Ensemble Kalman Filter in Power System State Tracking and Sensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yulan; Huang, Zhenyu; Zhou, Ning

2012-05-01

Ensemble Kalman Filter (EnKF) is proposed to track dynamic states of generators. The algorithm of EnKF and its application to generator state tracking are presented in detail. The accuracy and sensitivity of the method are analyzed with respect to initial state errors, measurement noise, unknown fault locations, time steps and parameter errors. It is demonstrated through simulation studies that even with some errors in the parameters, the developed EnKF can effectively track generator dynamic states using disturbance data.

AAA gunnermodel based on observer theory. [predicting a gunner's tracking response

NASA Technical Reports Server (NTRS)

Kou, R. S.; Glass, B. C.; Day, C. N.; Vikmanis, M. M.

1978-01-01

The Luenberger observer theory is used to develop a predictive model of a gunner's tracking response in antiaircraft artillery systems. This model is composed of an observer, a feedback controller and a remnant element. An important feature of the model is that the structure is simple, hence a computer simulation requires only a short execution time. A parameter identification program based on the least squares curve fitting method and the Gauss Newton gradient algorithm is developed to determine the parameter values of the gunner model. Thus, a systematic procedure exists for identifying model parameters for a given antiaircraft tracking task. Model predictions of tracking errors are compared with human tracking data obtained from manned simulation experiments. Model predictions are in excellent agreement with the empirical data for several flyby and maneuvering target trajectories.

The new Inner Tracking System of the ALICE experiment

NASA Astrophysics Data System (ADS)

Martinengo, P.; Alice Collaboration

2017-11-01

The ALICE experiment will undergo a major upgrade during the next LHC Long Shutdown scheduled in 2019-20 that will enable a detailed study of the properties of the QGP, exploiting the increased Pb-Pb luminosity expected during Run 3 and Run 4. The replacement of the existing Inner Tracking System with a completely new ultra-light, high-resolution detector is one of the cornerstones within this upgrade program. The main motivation of the ITS upgrade is to provide ALICE with an improved tracking capability and impact parameter resolution at very low transverse momentum, as well as to enable a substantial increase of the readout rate. The new ITS will consist of seven layers of innovative Monolithic Active Pixel Sensors with the innermost layer sitting at only 23 mm from the interaction point. This talk will focus on the design and the physics performance of the new ITS, as well as the technology choices adopted. The status of the project and the results from the prototypes characterization will also be presented.

Aeroelastic considerations for torsionally soft rotors

NASA Technical Reports Server (NTRS)

Mantay, W. R.; Yeager, W. T., Jr.

1985-01-01

A research study was initiated to systematically determine the impact of selected blade tip geometric parameters on conformable rotor performance and loads characteristics. The model articulated rotors included baseline and torsionally soft blades with interchangeable tips. Seven blade tip designs were evaluated on the baseline rotor and six tip designs were tested on the torsionally soft blades. The designs incorporated a systemmatic variation in geometric parameters including sweep, taper, and anhedral. The rotors were evaluated in the NASA Langley Transonic Dynamics Tunnel at several advance ratios, lift and propulsive force values, and tip Mach numbers. A track sensitivity study was also conducted at several advance ratios for both rotors. Based on the test results, tip parameter variations generated significant rotor performance and loads differences for both baseline and torsionally soft blades.

Operational Impact of Improved Space Tracking on Collision Avoidance in the Future LEO Space Debris Environment

NASA Astrophysics Data System (ADS)

Sibert, D.; Borgeson, D.; Peterson, G.; Jenkin, A.; Sorge, M.

2010-09-01

Even if global space policy successfully curtails on orbit explosions and ASAT demonstrations, studies indicate that the number of debris objects in Low Earth Orbit (LEO) will continue to grow solely from debris on debris collisions and debris generated from new launches. This study examines the threat posed by this growing space debris population over the next 30 years and how improvements in our space tracking capabilities can reduce the number of Collision Avoidance (COLA) maneuvers required keep the risk of operational satellite loss within tolerable limits. Particular focus is given to satellites operated by the Department of Defense (DoD) and Intelligence Community (IC) in Low Earth Orbit (LEO). The following debris field and space tracking performance parameters were varied parametrically in the experiment to study the impact on the number of collision avoidance maneuvers required: - Debris Field Density (by year 2009, 2019, 2029, and 2039) - Quality of Track Update (starting 1 sigma error ellipsoid) - Future Propagator Accuracy (error ellipsoid growth rates - Special Perturbations in 3 axes) - Track Update Rate for Debris (stochastic) - Track Update Rate for Payloads (stochastic) Baseline values matching present day tracking performance for quality of track update, propagator accuracy, and track update rate were derived by analyzing updates to the unclassified Satellite Catalog (SatCat). Track update rates varied significantly for active payloads and debris and as such we used different models for the track update rates for military payloads and debris. The analysis was conducted using the System Effectiveness Analysis Simulation (SEAS) an agent based model developed by the United States Air Force Space Command’s Space and Missile Systems Center to evaluate the military utility of space systems. The future debris field was modeled by The Aerospace Corporation using a tool chain which models the growth of the 10cm+ debris field using high fidelity propagation, collision, and breakup models. Our analysis uses Two Line Element (TLE) sets and surface area data generated by this model sampled at the years 2019, 2029, and 2039. Data for the 2009 debris field is taken from the unclassified SatCat. By using Monte Carlo simulation techniques and varying the epoch of the military constellation relative to the debris field we were able to remove the bias of initial conditions. Additional analysis was conducted looking at the military utility impact of temporarily losing the use of Intelligence Surveillance and Reconnaissance (ISR) assets due to COLA maneuvers during a large classified scenario with stressful satellite tasking. This paper and presentation will focus only on unclassified results quantifying the potential reduction in the risk assumed by satellite flyers, and the potential reduction in Delta-V usage that is possible if we are able to improve our tracking performance in any of these three areas and reduce the positional uncertainty of space objects at the time of closest approach.

Modelling, validation and analysis of a three-dimensional railway vehicle-track system model with linear and nonlinear track properties in the presence of wheel flats

NASA Astrophysics Data System (ADS)

Uzzal, R. U. A.; Ahmed, A. K. W.; Bhat, R. B.

2013-11-01

This paper presents dynamic contact loads at wheel-rail contact point in a three-dimensional railway vehicle-track model as well as dynamic response at vehicle-track component levels in the presence of wheel flats. The 17-degrees of freedom lumped mass vehicle is modelled as a full car body, two bogies and four wheelsets, whereas the railway track is modelled as two parallel Timoshenko beams periodically supported by lumped masses representing the sleepers. The rail beam is also supported by nonlinear spring and damper elements representing the railpad and ballast. In order to ensure the interactions between the railpads, a shear parameter beneath the rail beams has also been considered into the model. The wheel-rail contact is modelled using nonlinear Hertzian contact theory. In order to solve the coupled partial and ordinary differential equations of the vehicle-track system, modal analysis method is employed. Idealised Haversine wheel flats with the rounded corner are included in the wheel-rail contact model. The developed model is validated with the existing measured and analytical data available in the literature. The nonlinear model is then employed to investigate the wheel-rail impact forces that arise in the wheel-rail interface due to the presence of wheel flats. The validated model is further employed to investigate the dynamic responses of vehicle and track components in terms of displacement, velocity, and acceleration in the presence of single wheel flat.

Particle Filtering for Obstacle Tracking in UAS Sense and Avoid Applications

PubMed Central

Moccia, Antonio

2014-01-01

Obstacle detection and tracking is a key function for UAS sense and avoid applications. In fact, obstacles in the flight path must be detected and tracked in an accurate and timely manner in order to execute a collision avoidance maneuver in case of collision threat. The most important parameter for the assessment of a collision risk is the Distance at Closest Point of Approach, that is, the predicted minimum distance between own aircraft and intruder for assigned current position and speed. Since assessed methodologies can cause some loss of accuracy due to nonlinearities, advanced filtering methodologies, such as particle filters, can provide more accurate estimates of the target state in case of nonlinear problems, thus improving system performance in terms of collision risk estimation. The paper focuses on algorithm development and performance evaluation for an obstacle tracking system based on a particle filter. The particle filter algorithm was tested in off-line simulations based on data gathered during flight tests. In particular, radar-based tracking was considered in order to evaluate the impact of particle filtering in a single sensor framework. The analysis shows some accuracy improvements in the estimation of Distance at Closest Point of Approach, thus reducing the delay in collision detection. PMID:25105154

Track Geometry Development : UMTA Urban Rail Supporting Technology Program

DOT National Transportation Integrated Search

1974-04-01

Measurement of transit system track geometry parameters, under normal operating conditions, is essential for planning and conducting an effective maintenance program. The pertinent parameters are profile, gage, alignment, and cross level. Present met...

LAGEOS geodetic analysis-SL7.1

NASA Technical Reports Server (NTRS)

Smith, D. E.; Kolenkiewicz, R.; Dunn, P. J.; Klosko, S. M.; Robbins, J. W.; Torrence, M. H.; Williamson, R. G.; Pavlis, E. C.; Douglas, N. B.; Fricke, S. K.

1991-01-01

Laser ranging measurements to the LAGEOS satellite from 1976 through 1989 are related via geodetic and orbital theories to a variety of geodetic and geodynamic parameters. The SL7.1 analyses are explained of this data set including the estimation process for geodetic parameters such as Earth's gravitational constant (GM), those describing the Earth's elasticity properties (Love numbers), and the temporally varying geodetic parameters such as Earth's orientation (polar motion and Delta UT1) and tracking site horizontal tectonic motions. Descriptions of the reference systems, tectonic models, and adopted geodetic constants are provided; these are the framework within which the SL7.1 solution takes place. Estimates of temporal variations in non-conservative force parameters are included in these SL7.1 analyses as well as parameters describing the orbital states at monthly epochs. This information is useful in further refining models used to describe close-Earth satellite behavior. Estimates of intersite motions and individual tracking site motions computed through the network adjustment scheme are given. Tabulations of tracking site eccentricities, data summaries, estimated monthly orbital and force model parameters, polar motion, Earth rotation, and tracking station coordinate results are also provided.

TrackEtching - A Java based code for etched track profile calculations in SSNTDs

NASA Astrophysics Data System (ADS)

Muraleedhara Varier, K.; Sankar, V.; Gangadathan, M. P.

2017-09-01

A java code incorporating a user friendly GUI has been developed to calculate the parameters of chemically etched track profiles of ion-irradiated solid state nuclear track detectors. Huygen's construction of wavefronts based on secondary wavelets has been used to numerically calculate the etched track profile as a function of the etching time. Provision for normal incidence and oblique incidence on the detector surface has been incorporated. Results in typical cases are presented and compared with experimental data. Different expressions for the variation of track etch rate as a function of the ion energy have been utilized. The best set of values of the parameters in the expressions can be obtained by comparing with available experimental data. Critical angle for track development can also be calculated using the present code.

Miniregoliths. I - Dusty lunar rocks and lunar soil layers

NASA Technical Reports Server (NTRS)

Comstock, G. M.

1978-01-01

A detailed Monte-Carlo model for rock surface evolution shows that erosion processes alone cannot account for the shapes of the solar flare particle track profiles generally observed at depths of about 100 microns and less in rocks. The observed profiles are easily explained by a steady accumulation of fine dust at a rate of 0.3 to 3 mm per m.y., depending on the micrometeoroid impact rate which controls the dust cover and results in maximum dust thicknesses on the order of 100 microns to 1 mm. The commonly used lunar soil track parameters are derived in terms of parameters characterizing the exposure of soil grains in the few-millimeter-thick surface mixing and maturation zone which is one form of miniregolith. Correlation plots permit determining the degree of mixing in soil samples and the amount of processing (maturation) in surface miniregoliths. It is shown that the sampling process often artificially mixes together finer distinct layers, and that ancient miniregolith layers on the order of a millimeter thick are probably common in the lunar soil.

Discriminative detection of deposited radon daughters on CR-39 track detectors using TRIAC II code

NASA Astrophysics Data System (ADS)

Patiris, D. L.; Ioannides, K. G.

2009-07-01

A method for detecting deposited 218Po and 214Po by a spectrometric study of CR-39 solid state nuclear track detectors is described. The method is based on the application of software imposed selection criteria, concerning the geometrical and optical properties of the tracks, which correspond to tracks created by alpha particles of specific energy falling on the detector at given angles of incidence. The selection criteria were based on a preliminary study of tracks' parameters (major and minor axes and mean value of brightness), using the TRIAC II code. Since no linear relation was found between the energy and the geometric characteristics of the tracks (major and minor axes), we resorted to the use of an additional parameter in order to classify the tracks according to the particles' energy. Since the brightness of tracks is associated with the tracks' depth, the mean value of brightness was chosen as the parameter of choice. To reduce the energy of the particles, which are emitted by deposited 218Po and 214Po into a quantifiable range, the detectors were covered with an aluminum absorber material. In this way, the discrimination of radon's daughters was finally accomplished by properly selecting amongst all registered tracks. This method could be applied as a low cost tool for the study of the radon's daughters behavior in air.

Impact of mesh tracks and low-ground-pressure vehicle use on blanket peat hydrology

NASA Astrophysics Data System (ADS)

McKendrick-Smith, Kathryn; Holden, Joseph; Parry, Lauren

2016-04-01

Peatlands are subject to multiple uses including drainage, farming and recreation. Low-ground-pressure vehicle access is desirable by land owners and tracks facilitate access. However, there is concern that such activity may impact peat hydrology and so granting permission for track installation has been problematic, particularly without evidence for decision-making. We present the first comprehensive study of mesh track and low-ground-pressure vehicle impacts on peatland hydrology. In the sub-arctic oceanic climate of the Moor House World Biosphere Reserve in the North Pennines, UK, a 1.5 km long experimental track was installed to investigate hydrological impacts. Surface vegetation was cut and the plastic mesh track pinned into the peat surface. The experimental track was split into 7 treatments, designed to reflect typical track usage (0 - 5 vehicle passes per week) and varying vehicle weight. The greatest hydrological impacts were expected for sections of track subject to more frequent vehicle use and in close proximity to the track. In total 554 dipwells (including 15 automated recording at 15-min intervals) were monitored for water-table depth, positioned to capture potential spatial variability in response. Before track installation, samples for vertical and lateral hydraulic conductivity (Ks) analysis (using the modified cube method) were taken at 0-10 cm depth from a frequently driven treatment (n = 15), an infrequently driven treatment (0.5 passes per week) (n = 15) and a control site with no track/driving (n = 15). The test was repeated after 16 months of track use. We present a spatially and temporally rich water-table dataset from the study site showing how the impacts of the track on water table are spatially highly variable. Water-table depths across the site were shallow, typically within the upper 10 cm of the peat profile for > 75% of the time. We show that mesh track and low-ground-pressure vehicle impacts on water-table depth were small except for directly under and close to the track. Where the track runs parallel to the contours, water-tables were found to be deeper downslope of the track and shallower upslope. However in the no track/driving treatment; water table was significantly shallower downslope than upslope. Strong anisotropy was found in both 'before-track' and 'after-track' Ks, with horizontal Ks significantly greater than vertical Ks. No significant difference was found in vertical Ks before and after driving (medians 8.6 x 10-5 and 6.6 x 10-5 cm s-1 respectively). Horizontal Ks was significantly greater after driving (median 2.2 x 10-3 cm s-1) than before (median 3.7 x 10-4 cm s-1). Post-hoc testing highlights variability in response to treatment and topographic position. We suggest that this surprising result is related to rapid regrowth of new vegetation (particularly Sphagnum) through the mesh of the track, which was more dominant on horizontal Ks than the compression from low-ground-pressure vehicle use. Our results indicate that mesh tracks have a significant impact upon hydrology; however response is variable dependent upon topographic and seasonal factors. These findings can be used to inform land-management decision-making for the use of mesh tracks in peatlands.

The Influence of the North Atlantic Oscillation on Tropospheric Distributions of Ozone and Carbon Monoxide.

NASA Astrophysics Data System (ADS)

Knowland, K. E.; Doherty, R. M.; Hodges, K.

2015-12-01

The influence of the North Atlantic Oscillation (NAO) on the tropospheric distributions of ozone (O3) and carbon monoxide (CO) has been quantified. The Monitoring Atmospheric Composition and Climate (MACC) Reanalysis, a combined meteorology and composition dataset for the period 2003-2012 (Innes et al., 2013), is used to investigate the composition of the troposphere and lower stratosphere in relation to the location of the storm track as well as other meteorological parameters over the North Atlantic associated with the different NAO phases. Cyclone tracks in the MACC Reanalysis compare well to the cyclone tracks in the widely-used ERA-Interim Reanalysis for the same 10-year period (cyclone tracking performed using the tracking algorithm of Hodges (1995, 1999)), as both are based on the European Centre for Medium-Range Weather Forecasts' (ECMWF) Integrated Forecast System (IFS). A seasonal analysis is performed whereby the MACC reanalysis meteorological fields, O3 and CO mixing ratios are weighted by the monthly NAO index values. The location of the main storm track, which tilts towards high latitudes (toward the Arctic) during positive NAO phases to a more zonal location in the mid-latitudes (toward Europe) during negative NAO phases, impacts the location of both horizontal and vertical transport across the North Atlantic and into the Arctic. During positive NAO seasons, the persistence of cyclones over the North Atlantic coupled with a stronger Azores High promotes strong horizontal transport across the North Atlantic throughout the troposphere. In all seasons, significantly more intense cyclones occur at higher latitudes (north of ~50°C) during the positive phase of the NAO and in the southern mid-latitudes during the negative NAO phase. This impacts the location of stratospheric intrusions within the descending dry airstream behind the associated cold front of the extratropical cyclone and the venting of low-level pollution up into the free troposphere within the warm conveyor belt airstream which rises ahead of the cold front.

Hough transform method for track finding in center drift chamber

NASA Astrophysics Data System (ADS)

Azmi, K. A. Mohammad Kamal; Wan Abdullah, W. A. T.; Ibrahim, Zainol Abidin

2016-01-01

Hough transform is a global tracking method used which had been expected to be faster approach for tracking the circular pattern of electron moving in Center Drift Chamber (CDC), by transforming the point of hit into a circular curve. This paper present the implementation of hough transform method for the reconstruction of tracks in Center Drift Chamber (CDC) which have been generated by random number in C language programming. Result from implementation of this method shows higher peak of circle parameter value (xc,yc,rc) that indicate the similarity value of the parameter needed for circular track in CDC for charged particles in the region of CDC.

On the Impact of Localization and Density Control Algorithms in Target Tracking Applications for Wireless Sensor Networks

PubMed Central

Campos, Andre N.; Souza, Efren L.; Nakamura, Fabiola G.; Nakamura, Eduardo F.; Rodrigues, Joel J. P. C.

2012-01-01

Target tracking is an important application of wireless sensor networks. The networks' ability to locate and track an object is directed linked to the nodes' ability to locate themselves. Consequently, localization systems are essential for target tracking applications. In addition, sensor networks are often deployed in remote or hostile environments. Therefore, density control algorithms are used to increase network lifetime while maintaining its sensing capabilities. In this work, we analyze the impact of localization algorithms (RPE and DPE) and density control algorithms (GAF, A3 and OGDC) on target tracking applications. We adapt the density control algorithms to address the k-coverage problem. In addition, we analyze the impact of network density, residual integration with density control, and k-coverage on both target tracking accuracy and network lifetime. Our results show that DPE is a better choice for target tracking applications than RPE. Moreover, among the evaluated density control algorithms, OGDC is the best option among the three. Although the choice of the density control algorithm has little impact on the tracking precision, OGDC outperforms GAF and A3 in terms of tracking time. PMID:22969329

Vehicle response-based track geometry assessment using multi-body simulation

NASA Astrophysics Data System (ADS)

Kraft, Sönke; Causse, Julien; Coudert, Frédéric

2018-02-01

The assessment of the geometry of railway tracks is an indispensable requirement for safe rail traffic. Defects which represent a risk for the safety of the train have to be identified and the necessary measures taken. According to current standards, amplitude thresholds are applied to the track geometry parameters measured by recording cars. This geometry-based assessment has proved its value but suffers from the low correlation between the geometry parameters and the vehicle reactions. Experience shows that some defects leading to critical vehicle reactions are underestimated by this approach. The use of vehicle responses in the track geometry assessment process allows identifying critical defects and improving the maintenance operations. This work presents a vehicle response-based assessment method using multi-body simulation. The choice of the relevant operation conditions and the estimation of the simulation uncertainty are outlined. The defects are identified from exceedances of track geometry and vehicle response parameters. They are then classified using clustering methods and the correlation with vehicle response is analysed. The use of vehicle responses allows the detection of critical defects which are not identified from geometry parameters.

[Research on fuzzy proportional-integral-derivative control of master-slave minimally invasive operation robot driver].

PubMed

Zhao, Ximei; Ren, Chengyi; Liu, Hao; Li, Haogyi

2014-12-01

Robotic catheter minimally invasive operation requires that the driver control system has the advantages of quick response, strong anti-jamming and real-time tracking of target trajectory. Since the catheter parameters of itself and movement environment and other factors continuously change, when the driver is controlled using traditional proportional-integral-derivative (PID), the controller gain becomes fixed once the PID parameters are set. It can not change with the change of the parameters of the object and environmental disturbance so that its change affects the position tracking accuracy, and may bring a large overshoot endangering patients' vessel. Therefore, this paper adopts fuzzy PID control method to adjust PID gain parameters in the tracking process in order to improve the system anti-interference ability, dynamic performance and tracking accuracy. The simulation results showed that the fuzzy PID control method had a fast tracking performance and a strong robustness. Compared with those of traditional PID control, the feasibility and practicability of fuzzy PID control are verified in a robotic catheter minimally invasive operation.

Analysis of navigation performance for the Earth Observing System (EOS) using the TDRSS Onboard Navigation System (TONS)

NASA Technical Reports Server (NTRS)

Elrod, B.; Kapoor, A.; Folta, David C.; Liu, K.

1991-01-01

Use of the Tracking and Data Relay Satellite System (TDRSS) Onboard Navigation System (TONS) was proposed as an alternative to the Global Positioning System (GPS) for supporting the Earth Observing System (EOS) mission. The results are presented of EOS navigation performance evaluation with respect to TONS based orbit, time, and frequency determination (OD/TD/FD). Two TONS modes are considered: one uses scheduled TDRSS forward link service to derive one way Doppler tracking data for OD/FD support (TONS-I); the other uses an unscheduled navigation beacon service (proposed for Advanced TDRSS) to obtain pseudorange and Doppler data for OD/TD/FD support (TONS-II). Key objectives of the analysis were to evaluate nominal performance and potential sensitivities, such as suboptimal tracking geometry, tracking contact scheduling, and modeling parameter selection. OD/TD/FD performance predictions are presented based on covariance and simulation analyses. EOS navigation scenarios and the contributions of principal error sources impacting performance are also described. The results indicate that a TONS mode can be configured to meet current and proposed EOS position accuracy requirements of 100 and 50 m, respectively.

Curriculum Tracking and Teacher Evaluations of Individual Students: Selection, Adjustment or Labeling?

ERIC Educational Resources Information Center

Van Houtte, Mieke; Demanet, Jannick; Stevens, Peter A. J.

2013-01-01

Past research into the consequences of tracking mainly documented on the impact of attending different tracks on students' achievement and behavior. Less attention has been paid to the impact of track positions on teachers' perceptions and expectations regarding students. By means of multi-level analysis of data of 6,545 students in 46 Flemish…

Effects of railway track design on the expected degradation: Parametric study on energy dissipation

NASA Astrophysics Data System (ADS)

Sadri, Mehran; Steenbergen, Michaël

2018-04-01

This paper studies the effect of railway track design parameters on the expected long-term degradation of track geometry. The study assumes a geometrically perfect and straight track along with spatial invariability, except for the presence of discrete sleepers. A frequency-domain two-layer model is used of a discretely supported rail coupled with a moving unsprung mass. The susceptibility of the track to degradation is objectively quantified by calculating the mechanical energy dissipated in the substructure under a moving train axle for variations of different track parameters. Results show that, apart from the operational train speed, the ballast/substructure stiffness is the most significant parameter influencing energy dissipation. Generally, the degradation increases with the train speed and with softer substructures. However, stiff subgrades appear more sensitive to particular train velocities, in a regime which is mostly relevant for conventional trains (100-200 km/h) and less for high-speed operation, where a stiff subgrade is always favorable and can reduce the sensitivity to degradation substantially, with roughly a factor up to 7. Also railpad stiffness, sleeper distance and rail cross-sectional properties are found to have considerable effect, with higher expected degradation rates for increasing railpad stiffness, increasing sleeper distance and decreasing rail profile bending stiffness. Unsprung vehicle mass and sleeper mass have no significant influence, however, only against the background of the assumption of an idealized (invariant and straight) track. Apart from dissipated mechanical energy, the suitability of the dynamic track stiffness is explored as an engineering parameter to assess the sensitivity to degradation. It is found that this quantity is inappropriate to assess the design of an idealized track.

Hough transform method for track finding in center drift chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azmi, K. A. Mohammad Kamal, E-mail: khasmidatul@siswa.um.edu.my; Wan Abdullah, W. A. T., E-mail: wat@um.edu.my; Ibrahim, Zainol Abidin

Hough transform is a global tracking method used which had been expected to be faster approach for tracking the circular pattern of electron moving in Center Drift Chamber (CDC), by transforming the point of hit into a circular curve. This paper present the implementation of hough transform method for the reconstruction of tracks in Center Drift Chamber (CDC) which have been generated by random number in C language programming. Result from implementation of this method shows higher peak of circle parameter value (xc,yc,rc) that indicate the similarity value of the parameter needed for circular track in CDC for charged particlesmore » in the region of CDC.« less

Visual attention on a respiratory function monitor during simulated neonatal resuscitation: an eye-tracking study.

PubMed

Katz, Trixie A; Weinberg, Danielle D; Fishman, Claire E; Nadkarni, Vinay; Tremoulet, Patrice; Te Pas, Arjan B; Sarcevic, Aleksandra; Foglia, Elizabeth E

2018-06-14

A respiratory function monitor (RFM) may improve positive pressure ventilation (PPV) technique, but many providers do not use RFM data appropriately during delivery room resuscitation. We sought to use eye-tracking technology to identify RFM parameters that neonatal providers view most commonly during simulated PPV. Mixed methods study. Neonatal providers performed RFM-guided PPV on a neonatal manikin while wearing eye-tracking glasses to quantify visual attention on displayed RFM parameters (ie, exhaled tidal volume, flow, leak). Participants subsequently provided qualitative feedback on the eye-tracking glasses. Level 3 academic neonatal intensive care unit. Twenty neonatal resuscitation providers. Visual attention: overall gaze sample percentage; total gaze duration, visit count and average visit duration for each displayed RFM parameter. Qualitative feedback: willingness to wear eye-tracking glasses during clinical resuscitation. Twenty providers participated in this study. The mean gaze sample captured wa s 93% (SD 4%). Exhaled tidal volume waveform was the RFM parameter with the highest total gaze duration (median 23%, IQR 13-51%), highest visit count (median 5.17 per 10 s, IQR 2.82-6.16) and longest visit duration (median 0.48 s, IQR 0.38-0.81 s). All participants were willing to wear the glasses during clinical resuscitation. Wearable eye-tracking technology is feasible to identify gaze fixation on the RFM display and is well accepted by providers. Neonatal providers look at exhaled tidal volume more than any other RFM parameter. Future applications of eye-tracking technology include use during clinical resuscitation. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Tracking variable sedimentation rates in orbitally forced paleoclimate proxy series

NASA Astrophysics Data System (ADS)

Li, M.; Kump, L. R.; Hinnov, L.

2017-12-01

This study addresses two fundamental issues in cyclostratigraphy: quantitative testing of orbital forcing in cyclic sedimentary sequences and tracking variable sedimentation rates. The methodology proposed here addresses these issues as an inverse problem, and estimates the product-moment correlation coefficient between the frequency spectra of orbital solutions and paleoclimate proxy series over a range of "test" sedimentation rates. It is inspired by the ASM method (1). The number of orbital parameters involved in the estimation is also considered. The method relies on the hypothesis that orbital forcing had a significant impact on the paleoclimate proxy variations, and thus is also tested. The null hypothesis of no astronomical forcing is evaluated using the Beta distribution, for which the shape parameters are estimated using a Monte Carlo simulation approach. We introduce a metric to estimate the most likely sedimentation rate using the product-moment correlation coefficient, H0 significance level, and the number of contributing orbital parameters, i.e., the CHO value. The CHO metric is applied with a sliding window to track variable sedimentation rates along the paleoclimate proxy series. Two forward models with uniform and variable sedimentation rates are evaluated to demonstrate the robustness of the method. The CHO method is applied to the classical Late Triassic Newark depth rank series; the estimated sedimentation rates match closely with previously published sedimentation rates and provide a more highly time-resolved estimate (2,3). References: (1) Meyers, S.R., Sageman, B.B., Amer. J. Sci., 307, 773-792, 2007; (2) Kent, D.V., Olsen, P.E., Muttoni, G., Earth-Sci. Rev.166, 153-180, 2017; (3) Li, M., Zhang, Y., Huang, C., Ogg, J., Hinnov, L., Wang, Y., Zou, Z., Li, L., 2017. Earth Plant. Sc. Lett. doi:10.1016/j.epsl.2017.07.015

Muon reconstruction with a geometrical model in JUNO

NASA Astrophysics Data System (ADS)

Genster, C.; Schever, M.; Ludhova, L.; Soiron, M.; Stahl, A.; Wiebusch, C.

2018-03-01

The Jiangmen Neutrino Underground Observatory (JUNO) is a 20 kton liquid scintillator detector currently under construction near Kaiping in China. The physics program focuses on the determination of the neutrino mass hierarchy with reactor anti-neutrinos. For this purpose, JUNO is located 650 m underground with a distance of 53 km to two nuclear power plants. As a result, it is exposed to a muon flux that requires a precise muon reconstruction to make a veto of cosmogenic backgrounds viable. Established muon tracking algorithms use time residuals to a track hypothesis. We developed an alternative muon tracking algorithm that utilizes the geometrical shape of the fastest light. It models the full shape of the first, direct light produced along the muon track. From the intersection with the spherical PMT array, the track parameters are extracted with a likelihood fit. The algorithm finds a selection of PMTs based on their first hit times and charges. Subsequently, it fits on timing information only. On a sample of through-going muons with a full simulation of readout electronics, we report a spatial resolution of 20 cm of distance from the detector's center and an angular resolution of 1.6o over the whole detector. Additionally, a dead time estimation is performed to measure the impact of the muon veto. Including the step of waveform reconstruction on top of the track reconstruction, a loss in exposure of only 4% can be achieved compared to the case of a perfect tracking algorithm. When including only the PMT time resolution, but no further electronics simulation and waveform reconstruction, the exposure loss is only 1%.

Description and performance of track and primary-vertex reconstruction with the CMS tracker

DOE PAGES

Chatrchyan, Serguei

2014-10-16

A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For tbar t events under typical 2011 pileup conditions, the average track-reconstruction efficiency for promptly-produced charged particles with transverse momenta of p T > 0.9GeV is 94% for pseudorapidities of |η| < 0.9 and 85% for 0.9 < |η| < 2.5.more » The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of p T = 100GeV emitted at |η| < 1.4, the resolutions are approximately 2.8% in p T, and respectively, 10μm and 30μm in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10–12μm in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung.« less

Resist process optimization for further defect reduction

NASA Astrophysics Data System (ADS)

Tanaka, Keiichi; Iseki, Tomohiro; Marumoto, Hiroshi; Takayanagi, Koji; Yoshida, Yuichi; Uemura, Ryouichi; Yoshihara, Kosuke

2012-03-01

Defect reduction has become one of the most important technical challenges in device mass-production. Knowing that resist processing on a clean track strongly impacts defect formation in many cases, we have been trying to improve the track process to enhance customer yield. For example, residual type defect and pattern collapse are strongly related to process parameters in developer, and we have reported new develop and rinse methods in the previous papers. Also, we have reported the optimization method of filtration condition to reduce bridge type defects, which are mainly caused by foreign substances such as gels in resist. Even though we have contributed resist caused defect reduction in past studies, defect reduction requirements continue to be very important. In this paper, we will introduce further process improvements in terms of resist defect reduction, including the latest experimental data.

Effects of Retinal Eccentricity on Human Manual Control

NASA Technical Reports Server (NTRS)

Popovici, Alexandru; Zaal, Peter M. T.

2017-01-01

This study investigated the effects of viewing a primary flight display at different retinal eccentricities on human manual control behavior and performance. Ten participants performed a pitch tracking task while looking at a simplified primary flight display at different horizontal and vertical retinal eccentricities, and with two different controlled dynamics. Tracking performance declined at higher eccentricity angles and participants behaved more nonlinearly. The visual error rate gain increased with eccentricity for single-integrator-like controlled dynamics, but decreased for double-integrator-like dynamics. Participants' visual time delay was up to 100 ms higher at the highest horizontal eccentricity compared to foveal viewing. Overall, vertical eccentricity had a larger impact than horizontal eccentricity on most of the human manual control parameters and performance. Results might be useful in the design of displays and procedures for critical flight conditions such as in an aerodynamic stall.

3D Finite Element Analysis of Some Structural Modified PC Sleeper with the Vibration Characteristics between Sleeper and Ballast

NASA Astrophysics Data System (ADS)

Sakai, Hirotaka; Urakawa, Fumihiro; Aikawa, Akira; Namura, Akira

The vibration of concrete sleepers is an important factor engendering track deterioration. In this paper, we created a three-dimensional finite element model to reproduce a prestressed concrete (PC) sleeper in detail, expressing influence of ballast layers with a 3D spring series and dampers to reproduce their vibration and dynamic characteristics. Determination of these parameters bases on the experimental modal analysis using an impact excitation technique for PC sleepers by adjusting the accelerance between the analytical results and experimental results. Furthermore, we compared the difference of these characteristics between normal sleepers and those with some structural modifications. Analytical results clarified that such means as sleeper width extension and increased sleeper thickness will influence the reduction of ballasted track vibration as improvements of PC sleepers.

Tracking of cell nuclei for assessment of in vitro uptake kinetics in ultrasound-mediated drug delivery using fibered confocal fluorescence microscopy.

PubMed

Derieppe, Marc; de Senneville, Baudouin Denis; Kuijf, Hugo; Moonen, Chrit; Bos, Clemens

2014-10-01

Previously, we demonstrated the feasibility to monitor ultrasound-mediated uptake of a cell-impermeable model drug in real time with fibered confocal fluorescence microscopy. Here, we present a complete post-processing methodology, which corrects for cell displacements, to improve the accuracy of pharmacokinetic parameter estimation. Nucleus detection was performed based on the radial symmetry transform algorithm. Cell tracking used an iterative closest point approach. Pharmacokinetic parameters were calculated by fitting a two-compartment model to the time-intensity curves of individual cells. Cells were tracked successfully, improving time-intensity curve accuracy and pharmacokinetic parameter estimation. With tracking, 93 % of the 370 nuclei showed a fluorescence signal variation that was well-described by a two-compartment model. In addition, parameter distributions were narrower, thus increasing precision. Dedicated image analysis was implemented and enabled studying ultrasound-mediated model drug uptake kinetics in hundreds of cells per experiment, using fiber-based confocal fluorescence microscopy.

Exact-Output Tracking Theory for Systems with Parameter Jumps

NASA Technical Reports Server (NTRS)

Devasia, Santosh; Paden, Brad; Rossi, Carlo

1996-01-01

In this paper we consider the exact output tracking problem for systems with parameter jumps. Necessary and sufficient conditions are derived for the elimination of switching-introduced output transient. Previous works have studied this problem by developing a regulator that maintains exact tracking through parameter jumps (switches). Such techniques are, however, only applicable to minimum-phase systems. In contrast, our approach is applicable to nonminimum-phase systems and obtains bounded but possibly non-causal solutions. If the reference trajectories are generated by an exo-system, then we develop an exact-tracking controller in a feedback form. As in standard regulator theory, we obtain a linear map from the states of the exo-system to the desired system state which is defined via a matrix differential equation. The constant solution of this differential equation provides asymptotic tracking, and coincides with the feedback law used in standard regulator theory. The obtained results are applied to a simple flexible manipulator with jumps in the pay-load mass.

Exact-Output Tracking Theory for Systems with Parameter Jumps

NASA Technical Reports Server (NTRS)

Devasia, Santosh; Paden, Brad; Rossi, Carlo

1997-01-01

We consider the exact output tracking problem for systems with parameter jumps. Necessary and sufficient conditions are derived for the elimination of switching-introduced output transient. Previous works have studied this problem by developing a regulator that maintains exact tracking through parameter jumps (switches). Such techniques are, however, only applicable to minimum-phase systems. In contrast, our approach is applicable to non-minimum-phase systems and it obtains bounded but possibly non-causal solutions. If the reference trajectories are generated by an exosystem, then we develop an exact-tracking controller in a feed-back form. As in standard regulator theory, we obtain a linear map from the states of the exosystem to the desired system state which is defined via a matrix differential equation. The constant solution of this differential equation provides asymptotic tracking, and coincides with the feedback law used in standard regulator theory. The obtained results are applied to a simple flexible manipulator with jumps in the pay-load mass.

Different tracks for pathology informatics fellowship training: Experiences of and input from trainees in a large multisite fellowship program

PubMed Central

Levy, Bruce P.; McClintock, David S.; Lee, Roy E.; Lane, William J.; Klepeis, Veronica E.; Baron, Jason M.; Onozato, Maristela L.; Kim, JiYeon; Brodsky, Victor; Beckwith, Bruce; Kuo, Frank; Gilbertson, John R.

2012-01-01

Background: Pathology Informatics is a new field; a field that is still defining itself even as it begins the formalization, accreditation, and board certification process. At the same time, Pathology itself is changing in a variety of ways that impact informatics, including subspecialization and an increased use of data analysis. In this paper, we examine how these changes impact both the structure of Pathology Informatics fellowship programs and the fellows’ goals within those programs. Materials and Methods: As part of our regular program review process, the fellows evaluated the value and effectiveness of our existing fellowship tracks (Research Informatics, Clinical Two-year Focused Informatics, Clinical One-year Focused Informatics, and Clinical 1 + 1 Subspecialty Pathology and Informatics). They compared their education, informatics background, and anticipated career paths and analyzed them for correlations between those parameters and the fellowship track chosen. All current and past fellows of the program were actively involved with the project. Results: Fellows’ anticipated career paths correlated very well with the specific tracks in the program. A small set of fellows (Clinical – one or two year – Focused Informatics tracks) anticipated clinical careers primarily focused in informatics (Director of Informatics). The majority of the fellows, however, anticipated a career practicing in a Pathology subspecialty, using their informatics training to enhance that practice (Clinical 1 + 1 Subspecialty Pathology and Informatics Track). Significantly, all fellows on this track reported they would not have considered a Clinical Two-year Focused Informatics track if it was the only track offered. The Research and the Clinical One-year Focused Informatics tracks each displayed unique value for different situations. Conclusions: It seems a “one size fits all” fellowship structure does not fit the needs of the majority of potential Pathology Informatics candidates. Increasingly, these fellowships must be able to accommodate the needs of candidates anticipating a wide range of Pathology Informatics career paths, be able to accommodate Pathology's increasingly subspecialized structure, and do this in a way that respects the multiple fellowships needed to become a subspecialty pathologist and informatician. This is further complicated as Pathology Informatics begins to look outward and takes its place in the growing, and still ill-defined, field of Clinical Informatics, a field that is not confined to just one medical specialty, to one way of practicing medicine, or to one way of providing patient care. PMID:23024889

Satellite (IRLS) tracking of elk

NASA Technical Reports Server (NTRS)

Buechner, H. K.

1972-01-01

The practicability of tracking free roaming animals in natural environments by satellite systems is reported. Satellite systems combine continuous tracking with simultaneous monitoring of physiological and environmental parameters through a combination of radio tracking and biotelemetric ground systems that lead to a better understanding of animal behavior and migration patterns.

Anisotropic expansion and amorphization of Ga2O3 irradiated with 946 MeV Au ions

NASA Astrophysics Data System (ADS)

Tracy, Cameron L.; Lang, Maik; Severin, Daniel; Bender, Markus; Trautmann, Christina; Ewing, Rodney C.

2016-05-01

The structural response of β-Ga2O3 to irradiation-induced electronic excitation was investigated. A polycrystalline pellet of this material was irradiated with 946 MeV Au ions and the resulting structural modifications were characterized using in situ X-ray diffraction analysis at various ion fluences, up to 1 × 1013 cm-2. Amorphization was induced, with the accumulation of the amorphous phase following a single-impact mechanism in which each ion produces an amorphous ion track along its path. Concurrent with this phase transformation, an increase in the unit cell volume of the material was observed and quantified using Rietveld refinement. This unit cell expansion increased as a function of ion fluence before saturating at 1.8%. This effect is attributed to the generation of defects in an ion track shell region surrounding the amorphous track cores. The unit cell parameter increase was highly anisotropic, with no observed expansion in the [0 1 0] direction. This may be due to the structure of β-Ga2O3, which exhibits empty channels of connected interstitial sites oriented in this direction.

Tractometer: towards validation of tractography pipelines.

PubMed

Côté, Marc-Alexandre; Girard, Gabriel; Boré, Arnaud; Garyfallidis, Eleftherios; Houde, Jean-Christophe; Descoteaux, Maxime

2013-10-01

We have developed the Tractometer: an online evaluation and validation system for tractography processing pipelines. One can now evaluate the results of more than 57,000 fiber tracking outputs using different acquisition settings (b-value, averaging), different local estimation techniques (tensor, q-ball, spherical deconvolution) and different tracking parameters (masking, seeding, maximum curvature, step size). At this stage, the system is solely based on a revised FiberCup analysis, but we hope that the community will get involved and provide us with new phantoms, new algorithms, third party libraries and new geometrical metrics, to name a few. We believe that the new connectivity analysis and tractography characteristics proposed can highlight limits of the algorithms and contribute in solving open questions in fiber tracking: from raw data to connectivity analysis. Overall, we show that (i) averaging improves quality of tractography, (ii) sharp angular ODF profiles helps tractography, (iii) seeding and multi-seeding has a large impact on tractography outputs and must be used with care, and (iv) deterministic tractography produces less invalid tracts which leads to better connectivity results than probabilistic tractography. Copyright © 2013 Elsevier B.V. All rights reserved.

Data-based fault-tolerant control of high-speed trains with traction/braking notch nonlinearities and actuator failures.

PubMed

Song, Qi; Song, Yong-Duan

2011-12-01

This paper investigates the position and velocity tracking control problem of high-speed trains with multiple vehicles connected through couplers. A dynamic model reflecting nonlinear and elastic impacts between adjacent vehicles as well as traction/braking nonlinearities and actuation faults is derived. Neuroadaptive fault-tolerant control algorithms are developed to account for various factors such as input nonlinearities, actuator failures, and uncertain impacts of in-train forces in the system simultaneously. The resultant control scheme is essentially independent of system model and is primarily data-driven because with the appropriate input-output data, the proposed control algorithms are capable of automatically generating the intermediate control parameters, neuro-weights, and the compensation signals, literally producing the traction/braking force based upon input and response data only--the whole process does not require precise information on system model or system parameter, nor human intervention. The effectiveness of the proposed approach is also confirmed through numerical simulations.

Relationship of Physiological Parameters and Achievement in Wheelchair Athletics.

ERIC Educational Resources Information Center

Hurst, Judith A.

The relationship between achievement in track and field events (60, 100, 200, 400 meter runs and shotput, discus, and javelin throws) and selected physiological parameters (grip strength, body fat, vital lung capacity, and cardiovascular efficiency) of 20 wheelchair athletes was investigated. Results of track and field events were obtained from…

Influence of laser power on the penetration depth and geometry of scanning tracks in selective laser melting

NASA Astrophysics Data System (ADS)

Stopyra, Wojciech; Kurzac, Jarosław; Gruber, Konrad; Kurzynowski, Tomasz; Chlebus, Edward

2016-12-01

SLM technology allows production of a fully functional objects from metal and ceramic powders, with true density of more than 99,9%. The quality of manufactured items in SLM method affects more than 100 parameters, which can be divided into fixed and variable. Fixed parameters are those whose value before the process should be defined and maintained in an appropriate range during the process, e.g. chemical composition and morphology of the powder, oxygen level in working chamber, heating temperature of the substrate plate. In SLM technology, five parameters are variables that optimal set allows to produce parts without defects (pores, cracks) and with an acceptable speed. These parameters are: laser power, distance between points, time of exposure, distance between lines and layer thickness. To develop optimal parameters thin walls or single track experiments are performed, to select the best sets narrowed to three parameters: laser power, exposure time and distance between points. In this paper, the effect of laser power on the penetration depth and geometry of scanned single track was shown. In this experiment, titanium (grade 2) substrate plate was used and scanned by fibre laser of 1064 nm wavelength. For each track width, height and penetration depth of laser beam was measured.

Advancements in remote physiological measurement and applications in human-computer interaction

NASA Astrophysics Data System (ADS)

McDuff, Daniel

2017-04-01

Physiological signals are important for tracking health and emotional states. Imaging photoplethysmography (iPPG) is a set of techniques for remotely recovering cardio-pulmonary signals from video of the human body. Advances in iPPG methods over the past decade combined with the ubiquity of digital cameras presents the possibility for many new, lowcost applications of physiological monitoring. This talk will highlight methods for recovering physiological signals, work characterizing the impact of video parameters and hardware on these measurements, and applications of this technology in human-computer interfaces.

Exploration and extension of an improved Riemann track fitting algorithm

NASA Astrophysics Data System (ADS)

Strandlie, A.; Frühwirth, R.

2017-09-01

Recently, a new Riemann track fit which operates on translated and scaled measurements has been proposed. This study shows that the new Riemann fit is virtually as precise as popular approaches such as the Kalman filter or an iterative non-linear track fitting procedure, and significantly more precise than other, non-iterative circular track fitting approaches over a large range of measurement uncertainties. The fit is then extended in two directions: first, the measurements are allowed to lie on plane sensors of arbitrary orientation; second, the full error propagation from the measurements to the estimated circle parameters is computed. The covariance matrix of the estimated track parameters can therefore be computed without recourse to asymptotic properties, and is consequently valid for any number of observation. It does, however, assume normally distributed measurement errors. The calculations are validated on a simulated track sample and show excellent agreement with the theoretical expectations.

Impact of ADC parameters on linear optical sampling systems

NASA Astrophysics Data System (ADS)

Nguyen, Trung-Hien; Gay, Mathilde; Gomez-Agis, Fausto; Lobo, Sébastien; Sentieys, Olivier; Simon, Jean-Claude; Peucheret, Christophe; Bramerie, Laurent

2017-11-01

Linear optical sampling (LOS), based on the coherent photodetection of an optical signal under test with a low repetition-rate signal originating from a pulsed local oscillator (LO), enables the characterization of the temporal electric field of optical sources. Thanks to this technique, low-speed photodetectors and analog-to-digital converters (ADCs) can be integrated in the LOS system providing a cost-effective tool for characterizing high-speed signals. However, the impact of photodetector and ADC parameters on such LOS systems has not been explored in detail so far. These parameters, including the integration time of the track-and-hold function, the effective number of bits (ENOB) of the ADC, as well as the combined limited bandwidth of the photodetector and ADC are experimentally and numerically investigated in a LOS system for the first time. More specifically, by reconstructing 10-Gbit/s non-return-to-zero on-off keying (NRZ-OOK) and 10-Gbaud NRZ-quadrature phase-shift-keying (QPSK) signals, it is shown that a short integration time provides a better recovered signal fidelity. Furthermore, an ENOB of 6 bits and an ADC bandwidth normalized to the sampling rate of 2.8 are found to be sufficient in order to reliably monitor the considered signals.

U.S. Energy Disruptions

EIA Publications

EIA tracks and reports on selected significant storms that impact or could potentially impact energy infrastructure. See past historical events reported or real-time storm tracking with energy infrastructure maps.

The agreement between 3D, standard 2D and triplane 2D speckle tracking: effects of image quality and 3D volume rate.

PubMed

Trache, Tudor; Stöbe, Stephan; Tarr, Adrienn; Pfeiffer, Dietrich; Hagendorff, Andreas

2014-12-01

Comparison of 3D and 2D speckle tracking performed on standard 2D and triplane 2D datasets of normal and pathological left ventricular (LV) wall-motion patterns with a focus on the effect that 3D volume rate (3DVR), image quality and tracking artifacts have on the agreement between 2D and 3D speckle tracking. 37 patients with normal LV function and 18 patients with ischaemic wall-motion abnormalities underwent 2D and 3D echocardiography, followed by offline speckle tracking measurements. The values of 3D global, regional and segmental strain were compared with the standard 2D and triplane 2D strain values. Correlation analysis with the LV ejection fraction (LVEF) was also performed. The 3D and 2D global strain values correlated good in both normally and abnormally contracting hearts, though systematic differences between the two methods were observed. Of the 3D strain parameters, the area strain showed the best correlation with the LVEF. The numerical agreement of 3D and 2D analyses varied significantly with the volume rate and image quality of the 3D datasets. The highest correlation between 2D and 3D peak systolic strain values was found between 3D area and standard 2D longitudinal strain. Regional wall-motion abnormalities were similarly detected by 2D and 3D speckle tracking. 2DST of triplane datasets showed similar results to those of conventional 2D datasets. 2D and 3D speckle tracking similarly detect normal and pathological wall-motion patterns. Limited image quality has a significant impact on the agreement between 3D and 2D numerical strain values.

The influence of rail surface irregularities on contact forces and local stresses

NASA Astrophysics Data System (ADS)

Andersson, Robin; Torstensson, Peter T.; Kabo, Elena; Larsson, Fredrik

2015-01-01

The effect of initial rail surface irregularities on promoting further surface degradation is investigated. The study concerns rolling contact fatigue formation, in particular in the form of the so-called squats. The impact of surface irregularities in the form of dimples is quantified by peak magnitudes of dynamic contact stresses and contact forces. To this end simulations of two-dimensional (later extended to three-dimensional) vertical dynamic vehicle-track interaction are employed. The most influencing parameters are identified. It is shown that even very shallow dimples might have a large impact on local contact stresses. Peak magnitudes of contact forces and stresses due to the influence of rail dimples are shown to exceed those due to rail corrugation.

Determining Aerosol Plume Height from Two GEO Imagers: Lessons from MISR and GOES

NASA Technical Reports Server (NTRS)

Wu, Dong L.

2012-01-01

Aerosol plume height is a key parameter to determine impacts of particulate matters generated from biomass burning, wind-blowing dust, and volcano eruption. Retrieving cloud top height from stereo imageries from two GOES (Geostationary Operational Environmental Satellites) have been demonstrated since 1970's and the principle should work for aerosol plumes if they are optically thick. The stereo technique has also been used by MISR (Multiangle Imaging SpectroRadiometer) since 2000 that has nine look angles along track to provide aerosol height measurements. Knowing the height of volcano aerosol layers is as important as tracking the ash plume flow for aviation safety. Lack of knowledge about ash plume height during the 2010 Eyja'rjallajokull eruption resulted in the largest air-traffic shutdown in Europe since World War II. We will discuss potential applications of Asian GEO satellites to make stereo measurements for dust and volcano plumes.

Unraveling the Complexity of the Evolution of the Sun's Photospheric Magnetic Field

NASA Astrophysics Data System (ADS)

Hathaway, David H.

2016-10-01

Given the emergence of tilted, bipolar active regions, surface flux transport has been shown to reproduce much of the complex evolution of the Sun's photospheric magnetic field. Surface flux is transported by flows in the surface shear layer - the axisymmetric differential rotation and meridional flow and the non-axisymmetric convective motions (granules, supergranules, and giant cells). We have measured these flows by correlation tracking of the magnetic elements themselves, correlation tracking of the Doppler features (supergranules), and by direct Doppler measurements using SDO/HMI data. These measurements fully constrain (with no free parameters) the flows used in our surface flux transport code - the Advective Flux Transport or AFT code. Here we show the up-to-date evolution of these flows, their impact on the detailed evolution of the Sun's photospheric magnetic field, and predictions for what the polar fields will be at the next minimum in 2020.

Boundary Avoidance Tracking: Consequences (and Uses) of Imposed Boundaries on Pilot-Aircraft Performance

DTIC Science & Technology

2009-03-01

BOUNDARY AVOIDANCE TRACKING: CONSEQUENCES (AND USES) OF IMPOSED BOUNDARIES ON PILOT-AIRCRAFT...States Government. AFIT/GAE/ENY/09-M03 BOUNDARY AVOIDANCE TRACKING: CONSEQUENCES (AND USES) OF IMPOSED BOUNDARIES ON PILOT-AIRCRAFT PERFORMANCE...Case 2 (Gray, 2005) ....................................... 20 Figure 8. Effect of BAT Parameters on Tracking Success (Gray, 2005

LPV H-infinity Control for the Longitudinal Dynamics of a Flexible Air-Breathing Hypersonic Vehicle

NASA Astrophysics Data System (ADS)

Hughes, Hunter Douglas

This dissertation establishes the method needed to synthesize and simulate an Hinfinity Linear Parameter-Varying (LPV) controller for a flexible air-breathing hypersonic vehicle model. A study was conducted to gain the understanding of the elastic effects on the open loop system. It was determined that three modes of vibration would be suitable for the hypersonic vehicle model. It was also discovered from the open loop study that there is strong coupling in the hypersonic vehicle states, especially between the angle of attack, pitch rate, pitch attitude, and the exible modes of the vehicle. This dissertation outlines the procedure for synthesizing a full state feedback Hinfinity LPV controller for the hypersonic vehicle. The full state feedback study looked at both velocity and altitude tracking for the exible vehicle. A parametric study was conducted on each of these controllers to see the effects of changing the number of gridding points in the parameter space and changing the parameter variation rate limits in the system on the robust performance of the controller. As a result of the parametric study, a 7 x 7 grid ranging from Mach 7 to Mach 9 in velocity and from 70,000 feet to 90,000 feet in altitude, and a parameter variation rate limit of [.5 200]T was used for both the velocity tracking and altitude tracking cases. The resulting Hinfinity robust performances were gamma = 2.2224 for the velocity tracking case and = 1:7582 for the altitude tracking case. A linear analysis was then conducted on five different selected trim points from the Hinfinity LPV controller. This was conducted for the velocity tracking and altitude tracking cases. The results of linear analysis show that there is a slight difference in the response of the Hinfinity LPV controller and the fixed point H infinity controller. For the tracking task, the Hinfinity controller responds more quickly, and has a lower Hinfinity performance value. Next, the H infinity LPV controller was simulated using the nonlinear flexible hypersonic model for both the velocity tracking and altitude tracking cases. Both of these cases were subject to a ramp input and a multi-step input both with and without perturbation in the model. The results of the simulation show that the tracking state follows the command signal successfully though the perturbed system does show some higher frequency characteristics in the non-tracking states. It was discovered that there is an issue with integral windup when switching takes place in the controller, so an algorithm was implemented to reset the integration of the error on the tracking state when the switch takes place. It was also seen that there was a decline in altitude when tracking velocity, and a large change in velocity that occurred during altitude tracking. These results lead to the decision to include a unity gain regulation state on velocity for the altitude tracking and the altitude for the velocity tracking during the output feedback control synthesis. The procedure for synthesizing an output feedback H infinity LPV controller for the hypersonic vehicle is also discussed in this dissertation. The output feedback design looked at velocity tracking and altitude tracking with rigid body motion variables for both the exible and rigid body hypersonic vehicle models. As with the full state feedback controller, a parametric study was conducted on each of these controllers to determine the number of gridding points in the parameter space and the parameter variation rate limits in the system. The parametric study reveals a 7x7 grid ranging from Mach 7 to Mach 9 in velocity and from 70,000 feet to 90,000 feet in altitude, and a parameter variation rate limit of [.1 200]T is preferable for both the velocity tracking and altitude tracking cases with both the exible and rigid body assumptions. The resulting Hinfinity robust performances were gamma = 113:2146 for the exible body velocity tracking case, gamma = 83.6931 for the rigid body velocity tracking case, gamma = 107:2043 for the exible body altitude tracking case, and gamma = 97:7403 for the rigid body altitude tracking case. A linear analysis was then conducted on five different selected trim points from the Hinfinity LPV controller. The results of this analysis show that there is a larger difference in the response of the Hinfinity LPV controller and the Hinfinity controller. For the tracking task, the Hinfinity controller responds more quickly, and has a lower Hinfinity performance value. Next, the Hinfinity LPV controller was applied to the exible nonlinear plant model. The rigid body controllers were applied to the exible plant model to see if the exible nature of the vehicle could be treated as a perturbation to the system. Additionally, there were simulations run both with and without sensor noise and parametric uncertainty. The results of simulation show that the rigid body controller is able to successfully apply to the exible body model for the velocity tracking case, but is unable to stabilize the altitude tracking case. It was also seen that the system is able to track the command signal while minimizing the variations seen in the altitude for the velocity tracking case and in the velocity during the altitude tracking case. Additionally, there was no obvious effect of perturbations in the system on the tracking state or secondary regulation state. There were high frequency responses associated with the other perturbed states.

Modeling the effect of blunt impact on mitochondrial function in cartilage: implications for development of osteoarthritis.

PubMed

Kapitanov, Georgi I; Ayati, Bruce P; Martin, James A

2017-01-01

Osteoarthritis (OA) is a disease characterized by degeneration of joint cartilage. It is associated with pain and disability and is the result of either age and activity related joint wear or an injury. Non-invasive treatment options are scarce and prevention and early intervention methods are practically non-existent. The modeling effort presented in this article is constructed based on an emerging biological hypothesis-post-impact oxidative stress leads to cartilage cell apoptosis and hence the degeneration observed with the disease. The objective is to quantitatively describe the loss of cell viability and function in cartilage after an injurious impact and identify the key parameters and variables that contribute to this phenomenon. We constructed a system of differential equations that tracks cell viability, mitochondrial function, and concentrations of reactive oxygen species (ROS), adenosine triphosphate (ATP), and glycosaminoglycans (GAG). The system was solved using MATLAB and the equations' parameters were fit to existing data using a particle swarm algorithm. The model fits well the available data for cell viability, ATP production, and GAG content. Local sensitivity analysis shows that the initial amount of ROS is the most important parameter. The model we constructed is a viable method for producing in silico studies and with a few modifications, and data calibration and validation, may be a powerful predictive tool in the search for a non-invasive treatment for post-traumatic osteoarthritis.

Synchronisation, acquisition and tracking for telemetry and data reception

NASA Astrophysics Data System (ADS)

Vandoninck, A.

1992-06-01

The important parameters of synchronization, acquisition, and tracking are addressed, and each function is highlighted separately. The following sequence is such as the functions occur in the system in time and for the type of data to be received, with distinction between telemetry and data reception, between direct carrier modulation or the use of a subcarrier, and between deep space and normal reception. For the telemetry reception the acquisition is described taking into account the difference in performances as geostationary or polar orbits, and the dependencies on the different Doppler offsets and rates are distinguished. The related functions and parameters are covered and the specifications of an average receiver are summarized. The synchronization of the valid data is described with a distinction for data directly modulated or via a subcarrier, the type of modulation and bitrate. The relevant functions and parameters of the average receiver/demodulator are summarized. The tracking of the signal in the course of the operational phase is described and relevant parameters of an actual system are presented. The reception of real data is handled and a sequence of acquisition, synchronization, and tracking is applied. Here higher bitrates and direct modulation schemes play an important role. The market equipment with the relevant parameters are discussed. The three functions in cases where deep reception is needed are covered. The high performance receiver/demodulator functions and how the acquisition, synchronization, and tracking is handled in such application, are explained.

Investigation of the effects of sleeper-passing impacts on the high-speed train

NASA Astrophysics Data System (ADS)

Wu, Xingwen; Cai, Wubin; Chi, Maoru; Wei, Lai; Shi, Huailong; Zhu, Minhao

2015-12-01

The sleeper-passing impact has always been considered negligible in normal conditions, while the experimental data obtained from a High-speed train in a cold weather expressed significant sleeper-passing impacts on the axle box, bogie frame and car body. Therefore, in this study, a vertical coupled vehicle/track dynamic model was developed to investigate the sleeper-passing impacts and its effects on the dynamic performance of the high-speed train. In the model, the dynamic model of vehicle is established with 10 degrees of freedom. The track model is formulated with two rails supported on the discrete supports through the finite element method. The contact forces between the wheel and rail are estimated using the non-linear Hertz contact theory. The parametric studies are conducted to analyse effects of both the vehicle speeds and the discrete support stiffness on the sleeper-passing impacts. The results show that the sleeper-passing impacts become extremely significant with the increased support stiffness of track, especially when the frequencies of sleeper-passing impacts approach to the resonance frequencies of wheel/track system. The damping of primary suspension can effectively lower the magnitude of impacts in the resonance speed ranges, but has little effect on other speed ranges. Finally, a more comprehensively coupled vehicle/track dynamic model integrating with a flexible wheel set is developed to discuss the sleeper-passing-induced flexible vibration of wheel set.

Analytic Studies of the Relationship between Track Geometry Variations and Derailment Potential at Low Speeds

DOT National Transportation Integrated Search

1983-09-01

This report describes analytical studies carried out to define the relationship between track parameters and safety from derailment. Problematic track scenarios are identified reflecting known accident data. Vehicle response is investigated in the 10...

Analytical Studies of the Relationship Between Track Geometry Variations and Derailment Potential at Low Speeds

DOT National Transportation Integrated Search

1983-09-01

This report describes analytical studies carried out to define the relationship between track parameters and safety from derailment. Problematic track scenarios are identified reflecting known accident data. Vehicle response is investigated in the 10...

On the Efficiency Costs of De-Tracking Secondary Schools in Europe

ERIC Educational Resources Information Center

Brunello, Giorgio; Rocco, Lorenzo; Ariga, Kenn; Iwahashi, Roki

2012-01-01

Many European countries have delayed the time when school tracking starts in order to pursue equality of opportunity. What are the efficiency costs of de-tracking secondary schools? This paper builds a stylized model of the optimal time of tracking, estimates the relevant parameters using micro data for 11 European countries and computes the…

New constraints on Mars rotation determined from radiometric tracking of the Opportunity Mars Exploration Rover

NASA Astrophysics Data System (ADS)

Kuchynka, Petr; Folkner, William M.; Konopliv, Alex S.; Parker, Timothy J.; Park, Ryan S.; Le Maistre, Sebastien; Dehant, Veronique

2014-02-01

The Opportunity Mars Exploration Rover remained stationary between January and May 2012 in order to conserve solar energy for running its survival heaters during martian winter. While stationary, extra Doppler tracking was performed in order to allow an improved estimate of the martian precession rate. In this study, we determine Mars rotation by combining the new Opportunity tracking data with historic tracking data from the Viking and Pathfinder landers and tracking data from Mars orbiters (Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter). The estimated rotation parameters are stable in cross-validation tests and compare well with previously published values. In particular, the Mars precession rate is estimated to be -7606.1 ± 3.5 mas/yr. A representation of Mars rotation as a series expansion based on the determined rotation parameters is provided.

Radiation Measured for Chinese Satellite SJ-10 Space Mission

NASA Astrophysics Data System (ADS)

Zhou, Dazhuang; Sun, Yeqing; Zhang, Binquan; Zhang, Shenyi; Sun, Yueqiang; Liang, Jinbao; Zhu, Guangwu; Jing, Tao; Yuan, Bin; Zhang, Huanxin; Zhang, Meng; Wang, Wei; Zhao, Lei

2018-02-01

Space biological effects are mainly a result of space radiation particles with high linear energy transfer (LET); therefore, accurate measurement of high LET space radiation is vital. The radiation in low Earth orbits is composed mainly of high-energy galactic cosmic rays (GCRs), solar energetic particles, particles of radiation belts, the South Atlantic Anomaly, and the albedo neutrons and protons scattered from the Earth's atmosphere. CR-39 plastic nuclear track detectors sensitive to high LET are the best passive detectors to measure space radiation. The LET method that employs CR-39 can measure all the radiation LET spectra and quantities. CR-39 detectors can also record the incident directions and coordinates of GCR heavy ions that pass through both CR-39 and biosamples, and the impact parameter, the distance between the particle's incident point and the seed's spore, can then be determined. The radiation characteristics and impact parameter of GCR heavy ions are especially beneficial for in-depth research regarding space radiation biological effects. The payload returnable satellite SJ-10 provided an excellent opportunity to investigate space radiation biological effects with CR-39 detectors. The space bio-effects experiment was successfully conducted on board the SJ-10 satellite. This paper introduces space radiation in low Earth orbits and the LET method in radiation-related research and presents the results of nuclear tracks and biosamples hitting distributions of GCR heavy ions, the radiation LET spectra, and the quantities measured for the SJ-10 space mission. The SJ-10 bio-experiment indicated that radiation may produce significant bio-effects.

Experiment design for pilot identification in compensatory tracking tasks

NASA Technical Reports Server (NTRS)

Wells, W. R.

1976-01-01

A design criterion for input functions in laboratory tracking tasks resulting in efficient parameter estimation is formulated. The criterion is that the statistical correlations between pairs of parameters be reduced in order to minimize the problem of nonuniqueness in the extraction process. The effectiveness of the method is demonstrated for a lower order dynamic system.

Stardust Interstellar Preliminary Examination IX: High-Speed Interstellar Dust Analog Capture in Stardust Flight-Spare Aerogel

NASA Technical Reports Server (NTRS)

Postberg, F.; Sterken, V.; Achilles, C.; Allen, C.; Bastien, R. K.; Frank, D.; Sandford, S. A.; Zolensky, M. E.; Butterworth, A.; Gainesforth, Z.

2014-01-01

The NASA Stardust mission used silica aerogel slabs to slowly decelerate and capture impinging cosmic dust particles for return to Earth. During this process, impact tracks are generated along the trajectory of the particle into the aerogel. It is believed that the morphology and dimensions of these tracks, together with the state of captured grains at track termini, may be linked to the size, velocity, and density of the impacting cosmic dust grain. Here, we present the results of laboratory hypervelocity impact experiments, during which cosmic dust analog particles (diameters of between 0.2 and 0.4 lm), composed of olivine, orthopyroxene, or an organic polymer, were accelerated onto Stardust flight spare low-density (approximately 0.01 g/cu cm) silica aerogel. The impact velocities (3-21 km/s) were chosen to simulate the range of velocities expected during Stardust's interstellar dust (ISD) collection phases. Track lengths and widths, together with the success of particle capture, are analyzed as functions of impact velocity and particle composition, density, and size. Captured terminal particles from low-density organic projectiles become undetectable at lower velocities than those from similarly sized, denser mineral particles, which are still detectable (although substantially altered by the impact process) at 15 km/s. The survival of these terminal particles, together with the track dimensions obtained during low impact speed capture of small grains in the laboratory, indicates that two of the three best Stardust candidate extraterrestrial grains were actually captured at speeds much lower than predicted. Track length and diameters are, in general, more sensitive to impact velocities than previously expected, which makes tracks of particles with diameters of 0.4 lm and below hard to identify at low capture speeds (<10 km/s). Therefore, although captured intact, the majority of the interstellar dust grains returned to Earth by Stardust remain to be found.

Smoothing and Predicting Celestial Pole Offsets using a Kalman Filter and Smoother

NASA Astrophysics Data System (ADS)

Nastula, J.; Chin, T. M.; Gross, R. S.; Winska, M.; Winska, J.

2017-12-01

Since the early days of interplanetary spaceflight, accounting for changes in the Earth's rotation is recognized to be critical for accurate navigation. In the 1960s, tracking anomalies during the Ranger VII and VIII lunar missions were traced to errors in the Earth orientation parameters. As a result, Earth orientation calibration methods were improved to support the Mariner IV and V planetary missions. Today, accurate Earth orientation parameters are used to track and navigate every interplanetary spaceflight mission. The interplanetary spacecraft tracking and navigation teams at JPL require the UT1 and polar motion parameters, and these Earth orientation parameters are estimated by the use of a Kalman filter to combine past measurements of these parameters and predict their future evolution. A model was then used to provide the nutation/precession components of the Earth's orientation separately. As a result, variations caused by the free core nutation were not taken into account. But for the highest accuracy, these variations must be considered. So JPL recently developed an approach based upon the use of a Kalman filter and smoother to provide smoothed and predicted celestial pole offsets (CPOs) to the interplanetary spacecraft tracking and navigation teams. The approach used at JPL to do this and an evaluation of the accuracy of the predicted CPOs will be given here.

Tracking radar studies of bird migration

NASA Technical Reports Server (NTRS)

Williams, T. C.; Williams, J. M.; Teal, J. M.; Kanwisher, J. W.

1972-01-01

The application of tracking radar for determining the flight paths of migratory birds is discussed. The effects produced by various meteorological parameters are described. Samples of radar scope presentations obtained during tracking studies are presented. The characteristics of the radars and their limitations are examined.

The role of water tracks in altering biotic and abiotic soil properties and processes in a polar desert in Antarctica

NASA Astrophysics Data System (ADS)

Ball, Becky A.; Levy, Joseph

2015-02-01

Groundwater discharge via water tracks is a largely unexplored passageway routing salts and moisture from high elevations to valley floors in the McMurdo Dry Valleys (MDV) of Antarctica. Given the influence that water tracks have on the distribution of liquid water in seasonally thawed Antarctic soils, it is surprising how little is known about their role in structuring biotic and abiotic processes this cold desert ecosystem. Particularly, it is unclear how soil biota will respond to the activation of new water tracks resulting from enhanced active layer thickening or enhanced regional snowmelt. In the MDV, water tracks are both wetter and more saline than the surrounding soils, constituting a change in soil habitat suitability for soil biology and therefore the ecological processes they carry out. To investigate the net impact that water tracks have on Dry Valley soil biology, and therefore the ecosystem processes for which they are responsible, we analyzed microbial biomass and activity in soils inside and outside of three water tracks and relate this to the physical soil characteristics. Overall, our results suggest that water tracks can significantly influence soil properties, which can further impact biological biovolume and both biotic and abiotic fluxes of CO2. However, the nature of its impact differs with water track, further suggesting that not all water tracks can be regarded the same.

Tracking and Sense of Futility: The Impact of Between-School Tracking versus Within-School Tracking in Secondary Education in Flanders (Belgium)

ERIC Educational Resources Information Center

Van Houtte, Mieke; Stevens, Peter A. J.

2015-01-01

It has been established since the 1960s that tracking yields negative consequences for students in lower tracks. As this research has been carried out mainly in the USA and UK, the effects of tracking have been demonstrated in systems of within-school tracking mostly. However, in many European countries--such as Belgium (Flanders)--tracking is…

Single-chip microcomputer for image processing in the photonic measuring system

NASA Astrophysics Data System (ADS)

Smoleva, Olga S.; Ljul, Natalia Y.

2002-04-01

The non-contact measuring system has been designed for rail- track parameters control on the Moscow Metro. It detects some significant parameters: rail-track width, rail-track height, gage, rail-slums, crosslevel, pickets, and car speed. The system consists of three subsystems: non-contact system of rail-track width, height, and gage inspection, non-contact system of rail-slums inspection and subsystem for crosslevel, speed, and pickets detection. Data from subsystems is transferred to pre-processing unit. In order to process data received from subsystems, the single-chip signal processor ADSP-2185 must be used due to providing required processing speed. After data will be processed, it is send to PC, which processes it and outputs it in the readable form.

Novel Approaches to Improve Iris Recognition System Performance Based on Local Quality Evaluation and Feature Fusion

PubMed Central

2014-01-01

For building a new iris template, this paper proposes a strategy to fuse different portions of iris based on machine learning method to evaluate local quality of iris. There are three novelties compared to previous work. Firstly, the normalized segmented iris is divided into multitracks and then each track is estimated individually to analyze the recognition accuracy rate (RAR). Secondly, six local quality evaluation parameters are adopted to analyze texture information of each track. Besides, particle swarm optimization (PSO) is employed to get the weights of these evaluation parameters and corresponding weighted coefficients of different tracks. Finally, all tracks' information is fused according to the weights of different tracks. The experimental results based on subsets of three public and one private iris image databases demonstrate three contributions of this paper. (1) Our experimental results prove that partial iris image cannot completely replace the entire iris image for iris recognition system in several ways. (2) The proposed quality evaluation algorithm is a self-adaptive algorithm, and it can automatically optimize the parameters according to iris image samples' own characteristics. (3) Our feature information fusion strategy can effectively improve the performance of iris recognition system. PMID:24693243

Novel approaches to improve iris recognition system performance based on local quality evaluation and feature fusion.

PubMed

Chen, Ying; Liu, Yuanning; Zhu, Xiaodong; Chen, Huiling; He, Fei; Pang, Yutong

2014-01-01

For building a new iris template, this paper proposes a strategy to fuse different portions of iris based on machine learning method to evaluate local quality of iris. There are three novelties compared to previous work. Firstly, the normalized segmented iris is divided into multitracks and then each track is estimated individually to analyze the recognition accuracy rate (RAR). Secondly, six local quality evaluation parameters are adopted to analyze texture information of each track. Besides, particle swarm optimization (PSO) is employed to get the weights of these evaluation parameters and corresponding weighted coefficients of different tracks. Finally, all tracks' information is fused according to the weights of different tracks. The experimental results based on subsets of three public and one private iris image databases demonstrate three contributions of this paper. (1) Our experimental results prove that partial iris image cannot completely replace the entire iris image for iris recognition system in several ways. (2) The proposed quality evaluation algorithm is a self-adaptive algorithm, and it can automatically optimize the parameters according to iris image samples' own characteristics. (3) Our feature information fusion strategy can effectively improve the performance of iris recognition system.

Numerical simulation of active track tensioning system for autonomous hybrid vehicle

NASA Astrophysics Data System (ADS)

Mȩżyk, Arkadiusz; Czapla, Tomasz; Klein, Wojciech; Mura, Gabriel

2017-05-01

One of the most important components of a high speed tracked vehicle is an efficient suspension system. The vehicle should be able to operate both in rough terrain for performance of engineering tasks as well as on the road with high speed. This is especially important for an autonomous platform that operates either with or without human supervision, so that the vibration level can rise compared to a manned vehicle. In this case critical electronic and electric parts must be protected to ensure the reliability of the vehicle. The paper presents a dynamic parameters determination methodology of suspension system for an autonomous high speed tracked platform with total weight of about 5 tonnes and hybrid propulsion system. Common among tracked vehicles suspension solutions and cost-efficient, the torsion-bar system was chosen. One of the most important issues was determining optimal track tensioning - in this case an active hydraulic system was applied. The selection of system parameters was performed with using numerical model based on multi-body dynamic approach. The results of numerical analysis were used to define parameters of active tensioning control system setup. LMS Virtual.Lab Motion was used for multi-body dynamics numerical calculation and Matlab/SIMULINK for control system simulation.

Predicting dredging-associated effects to coral reefs in Apra Harbor, Guam - Part 1: Sediment exposure modeling.

PubMed

Gailani, Joseph Z; Lackey, Tahirih C; King, David B; Bryant, Duncan; Kim, Sung-Chan; Shafer, Deborah J

2016-03-01

Model studies were conducted to investigate the potential coral reef sediment exposure from dredging associated with proposed development of a deepwater wharf in Apra Harbor, Guam. The Particle Tracking Model (PTM) was applied to quantify the exposure of coral reefs to material suspended by the dredging operations at two alternative sites. Key PTM features include the flexible capability of continuous multiple releases of sediment parcels, control of parcel/substrate interaction, and the ability to efficiently track vast numbers of parcels. This flexibility has facilitated simulating the combined effects of sediment released from clamshell dredging and chiseling within Apra Harbor. Because the rate of material released into the water column by some of the processes is not well understood or known a priori, the modeling approach was to bracket parameters within reasonable ranges to produce a suite of potential results from multiple model runs. Sensitivity analysis to model parameters is used to select the appropriate parameter values for bracketing. Data analysis results include mapping the time series and the maximum values of sedimentation, suspended sediment concentration, and deposition rate. Data were used to quantify various exposure processes that affect coral species in Apra Harbor. The goal of this research is to develop a robust methodology for quantifying and bracketing exposure mechanisms to coral (or other receptors) from dredging operations. These exposure values were utilized in an ecological assessment to predict effects (coral reef impacts) from various dredging scenarios. Copyright © 2015. Published by Elsevier Ltd.

Determination of nuclear tracks parameters on sequentially etched PADC detectors

NASA Astrophysics Data System (ADS)

Horwacik, Tomasz; Bilski, Pawel; Koerner, Christine; Facius, Rainer; Berger, Thomas; Nowak, Tomasz; Reitz, Guenther; Olko, Pawel

Polyallyl Diglycol Carbonate (PADC) detectors find many applications in radiation protection. One of them is the cosmic radiation dosimetry, where PADC detectors measure the linear energy transfer (LET) spectra of charged particles (from protons to heavy ions), supplementing TLD detectors in the role of passive dosemeter. Calibration exposures to ions of known LET are required to establish a relation between parameters of track observed on the detector and LET of particle creating this track. PADC TASTRAK nuclear track detectors were exposed to 12 C and 56 Fe ions of LET in H2 O between 10 and 544 keV/µm. The exposures took place at the Heavy Ion Medical Accelerator (HIMAC) in Chiba, Japan in the frame of the HIMAC research project "Space Radiation Dosimetry-Ground Based Verification of the MATROSHKA Facility" (20P-240). Detectors were etched in water solution of NaOH with three different temperatures and for various etching times to observe the appearance of etched tracks, the evolution of their parameters and the stability of the etching process. The applied etching times (and the solution's concentrations and temperatures) were: 48, 72, 96, 120 hours (6.25 N NaOH, 50 O C), 20, 40, 60, 80 hours (6.25 N NaOH, 60 O C) and 8, 12, 16, 20 hours (7N NaOH, 70 O C). The analysis of the detectors involved planimetric (2D) measurements of tracks' entrance ellipses and mechanical measurements of bulk layer thickness. Further track parameters, like angle of incidence, track length and etch rate ratio were then calculated. For certain tracks, results of planimetric measurements and calculations were also compared with results of optical track profile (3D) measurements, where not only the track's entrance ellipse but also the location of the track's tip could be directly measured. All these measurements have been performed with the 2D/3D measurement system at DLR. The collected data allow to create sets of V(LET in H2 O) calibration curves suitable for short, intermediate and long etching time and will be use during analysis of detectors exposed on the International Space Station during DOSIS and MATROSHKA experiments. The help and support of Yukio Uchihori and Hisashi Kitamura during the irradiations at HIMAC is highly appreciated. This work was supported by the Polish Ministry of Science and Higher Education, grants: No N N505 261535 and No. DWM/N118/ESA/2008.

Mass-loss rates of cool stars

NASA Astrophysics Data System (ADS)

Katrien Els Decin, Leen

2015-08-01

Over much of the initial mass function, stars lose a significant fraction of their mass through a stellar wind during the late stages of their evolution when being a (super)giant star. As of today, we can not yet predict the mass-loss rate during the (super)giant phase for a given star with specific stellar parameters from first principles. This uncertainty directly impacts the accuracy of current stellar evolution and population synthesis models that predict the enrichment of the interstellar medium by these stellar winds. Efforts to establish the link between the initial physical and chemical conditions at stellar birth and the mass-loss rate during the (super)giant phase have proceeded on two separate tracks: (1) more detailed studies of the chemical and morpho-kinematical structure of the stellar winds of (super)giant stars in our own Milky Way by virtue of the proximity, and (2) large scale and statistical studies of a (large) sample of stars in other galaxies (such as the LMC and SMC) and globular clusters eliminating the uncertainty on the distance estimate and providing insight into the dependence of the mass-loss rate on the metallicity. In this review, I will present recent results of both tracks, will show how recent measurements confirm (some) theoretical predictions, but also how results from the first track admonish of common misconceptions inherent in the often more simplified analysis used to analyse the large samples from track 2.

A Review of Nutritional Tracking Mobile Applications for Diabetes Patient Use.

PubMed

Darby, Alaina; Strum, Matthew W; Holmes, Erin; Gatwood, Justin

2016-03-01

Diabetes, a prevalent disease in the United States, is greatly impacted by lifestyle choices, notably nutrition. The goal of this research was to determine which of the nutritional tracking applications (apps) available for Apple (Cupertino, CA) iOS, Android® (Google, Mountain View, CA), and Windows (Microsoft, Redmond, WA) platforms should be a first recommendation to diabetes patients searching for a smartphone app to aid in dietary logging and, for some apps, other varying lifestyle and health data. This project did so by identifying the smartphone apps available on the iTunes® (Apple), Google Play, and Microsoft stores that have nutritional tracking capabilities and are of potential benefit to a patient with diabetes based on certain criteria. Each of the individual apps was then evaluated to determine which would be of most benefit to a diabetes patient. The apps were assessed based on several parameters, such as their food databases, logging options, additional tracking options, interoperability with other devices and apps, and diabetes-specific resources. This information was then compiled and evaluated to determine which apps would be of most benefit for diabetes patients. This research provides valuable information for both patients and healthcare providers because the results of this study can be used as a reference for practitioners wishing to make app recommendations for diabetes patients who are implementing lifestyle change as an aspect of therapy.

Intercomparison of mid latitude storm diagnostics (IMILAST) - synthesis of project results

NASA Astrophysics Data System (ADS)

Neu, Urs

2017-04-01

The analysis of the occurrence of mid-latitude storms is of great socio-economical interest due to their vast and destructive impacts. However, a unique definition of cyclones is missing, and therefore the definition of what a cyclone is as well as quantifying its strength contains subjective choices. Existing automatic cyclone identification and tracking algorithms are based on different definitions and use diverse characteristics, e.g. data transformation, metrics used for cyclone identification, cyclone identification procedures or tracking methods. The project IMILAST systematically compares different cyclone detection and tracking methods, with the aim to comprehensively assess the influence of different algorithms on cyclone climatologies, temporal trends of frequency, strength or other characteristics of cyclones and thus quantify systematic uncertainties in mid-latitudinal storm identification and tracking. The three main intercomparison experiments used the ERA-interim reanalysis as a common input data set and focused on differences between the methods with respect to number, track density, life cycle characteristics, and trend patterns on the one hand and potential differences of the long-term climate change signal of cyclonic activity between the methods on the other hand. For the third experiment, the intercomparison period has been extended to a 30 year period from 1979 to 2009 and focuses on more specific aspects, such as parameter sensitivities, the comparison of automated to manual tracking sets, regional analysis (regional trends, Arctic and Antarctic cyclones, cyclones in the Mediterranean) or specific phenomena like splitting and merging of cyclones. In addition, the representation of storms and their characteristics in reanalysis data sets is examined to further enhance the knowledge on uncertainties related to storm occurrence. This poster presents a synthesis of the main results from the intercomparison activities within IMILAST.

Measurement-based perturbation theory and differential equation parameter estimation with applications to satellite gravimetry

NASA Astrophysics Data System (ADS)

Xu, Peiliang

2018-06-01

The numerical integration method has been routinely used by major institutions worldwide, for example, NASA Goddard Space Flight Center and German Research Center for Geosciences (GFZ), to produce global gravitational models from satellite tracking measurements of CHAMP and/or GRACE types. Such Earth's gravitational products have found widest possible multidisciplinary applications in Earth Sciences. The method is essentially implemented by solving the differential equations of the partial derivatives of the orbit of a satellite with respect to the unknown harmonic coefficients under the conditions of zero initial values. From the mathematical and statistical point of view, satellite gravimetry from satellite tracking is essentially the problem of estimating unknown parameters in the Newton's nonlinear differential equations from satellite tracking measurements. We prove that zero initial values for the partial derivatives are incorrect mathematically and not permitted physically. The numerical integration method, as currently implemented and used in mathematics and statistics, chemistry and physics, and satellite gravimetry, is groundless, mathematically and physically. Given the Newton's nonlinear governing differential equations of satellite motion with unknown equation parameters and unknown initial conditions, we develop three methods to derive new local solutions around a nominal reference orbit, which are linked to measurements to estimate the unknown corrections to approximate values of the unknown parameters and the unknown initial conditions. Bearing in mind that satellite orbits can now be tracked almost continuously at unprecedented accuracy, we propose the measurement-based perturbation theory and derive global uniformly convergent solutions to the Newton's nonlinear governing differential equations of satellite motion for the next generation of global gravitational models. Since the solutions are global uniformly convergent, theoretically speaking, they are able to extract smallest possible gravitational signals from modern and future satellite tracking measurements, leading to the production of global high-precision, high-resolution gravitational models. By directly turning the nonlinear differential equations of satellite motion into the nonlinear integral equations, and recognizing the fact that satellite orbits are measured with random errors, we further reformulate the links between satellite tracking measurements and the global uniformly convergent solutions to the Newton's governing differential equations as a condition adjustment model with unknown parameters, or equivalently, the weighted least squares estimation of unknown differential equation parameters with equality constraints, for the reconstruction of global high-precision, high-resolution gravitational models from modern (and future) satellite tracking measurements.

Thermal buckling and post-buckling behaviour of continuous welded rail track

NASA Astrophysics Data System (ADS)

Pucillo, Giovanni Pio

2016-12-01

Because thermal expansions are constrained within continuous welded rail track, the track can buckle, and does so mainly in the horizontal plane. In this paper, a parametric finite element model of railway track is presented, and its sensitivity to the variations of the main parameters that characterise the scenario has been investigated and discussed. Comparison with existing literature shows good agreement. It is found that curved tracks suffer from thermal buckling more than tangent tracks do. To simulate a track misalignment defect, a new methodology has been utilised that does not introduce, as is usual, geometrical discontinuities near the same defect, because it takes into account - in a natural way - the bending stiffness of the whole railway track in the horizontal plane. To contribute to a better understanding of the safe utilisation of raw experimental data obtained from in situ tests, a deep analysis of the effects on the thermal track buckling response produced by each parameter characterising the sleeper-ballast lateral resistance curve is presented and discussed. It is found that for current ballasted railway tracks, the minimum buckling temperature depends only on the limit lateral resistance, whereas a high value of the initial stiffness can lead to overestimation of the maximum buckling temperature, also taking into account the 'natural' decrease in the maximum buckling temperature due to an increase in the railway-traffic-induced defect amplitude.

Image processing analysis of nuclear track parameters for CR-39 detector irradiated by thermal neutron

NASA Astrophysics Data System (ADS)

Al-Jobouri, Hussain A.; Rajab, Mustafa Y.

2016-03-01

CR-39 detector which covered with boric acid (H3Bo3) pellet was irradiated by thermal neutrons from (241Am - 9Be) source with activity 12Ci and neutron flux 105 n. cm-2. s-1. The irradiation times -TD for detector were 4h, 8h, 16h and 24h. Chemical etching solution for detector was sodium hydroxide NaOH, 6.25N with 45 min etching time and 60 C˚ temperature. Images of CR-39 detector after chemical etching were taken from digital camera which connected from optical microscope. MATLAB software version 7.0 was used to image processing. The outputs of image processing of MATLAB software were analyzed and found the following relationships: (a) The irradiation time -TD has behavior linear relationships with following nuclear track parameters: i) total track number - NT ii) maximum track number - MRD (relative to track diameter - DT) at response region range 2.5 µm to 4 µm iii) maximum track number - MD (without depending on track diameter - DT). (b) The irradiation time -TD has behavior logarithmic relationship with maximum track number - MA (without depending on track area - AT). The image processing technique principally track diameter - DT can be take into account to classification of α-particle emitters, In addition to the contribution of these technique in preparation of nano- filters and nano-membrane in nanotechnology fields.

tropical cyclone risk analysis: a decisive role of its track

NASA Astrophysics Data System (ADS)

Chelsea Nam, C.; Park, Doo-Sun R.; Ho, Chang-Hoi

2016-04-01

The tracks of 85 tropical cyclones (TCs) that made landfall to South Korea for the period 1979-2010 are classified into four clusters by using a fuzzy c-means clustering method. The four clusters are characterized by 1) east-short, 2) east-long, 3) west-long, and 4) west-short based on the moving routes around Korean peninsula. We conducted risk comparison analysis for these four clusters regarding their hazards, exposure, and damages. Here, hazard parameters are calculated from two different sources independently, one from the best-track data (BT) and the other from the 60 weather stations over the country (WS). The results show distinct characteristics of the four clusters in terms of the hazard parameters and economic losses (EL), suggesting that there is a clear track-dependency in the overall TC risk. It is appeared that whether there occurred an "effective collision" overweighs the intensity of the TC per se. The EL ranking did not agree with the BT parameters (maximum wind speed, central pressure, or storm radius), but matches to WS parameter (especially, daily accumulated rainfall and TC-influenced period). The west-approaching TCs (i.e. west-long and west-short clusters) generally recorded larger EL than the east-approaching TCs (i.e. east-short and east-long clusters), although the east-long clusters are the strongest in BT point of view. This can be explained through the spatial distribution of the WS parameters and the regional EL maps corresponding to it. West-approaching TCs accompanied heavy rainfall on the southern regions with the helps of the topographic effect on their tracks, and of the extended stay on the Korean Peninsula in their extratropical transition, that were not allowed to the east-approaching TCs. On the other hand, some regions had EL that are not directly proportional to the hazards, and this is partly attributed to spatial disparity in wealth and vulnerability. Correlation analysis also revealed the importance of rainfall; daily accumulated rainfall is the most-correlated with EL among all BT and WS hazard parameters for all clusters except the east-short. The least-correlated hazard parameter is the storm radius which showed significant correlations with EL for only the short clusters. In conclusion, this study suggests that TC track is essential in determining the way it brings damage on South Korea. Thus, it is suggested that the damage warning and adaptation policy need to be different for different TC tracks although South Korea is relatively small compared to average TC size.

Estimating on-orbit optical properties for GNSS satellites

NASA Astrophysics Data System (ADS)

Rodriguez Solano, M. Sc. Carlos Javier; Hugentobler, Urs; Steigenberger, Peter

One of the major uncertainty sources affecting GNSS satellite orbits is the direct solar radiation pressure. Other important though smaller effects are caused by deviations of the satellite from nominal attitude, Earth radiation pressure and thermal re-radiation forces. To compensate such effects, the IGS Analysis Centers usually estimate empirical parameters which fit best the tracking data obtained from a global network of GNSS ground stations to compute orbits at an accuracy level of 2.5 cm for GPS and of 5 cm for GLONASS. On the other hand, there are also accurate physical models for the above mentioned non-conservative forces affecting the GNSS satellites such as the ROCK models for GPS satellites. However, current models fail to predict the real orbit behaviour with sufficient accuracy, mainly due to deviations from nominal attitude, from inaccurately known optical properties, or from aging of the satellite surfaces. In this context an analytical box-wing model has been derived based on the physical interaction between the direct solar radiation and a satellite consisting of a bus (box shape) and solar panels. Furthermore some of the parameters of the box-wing model can be adjusted to fit the GNSS tracking data, namely the fraction of reflected photons of the corresponding satellite surfaces. For this study GNSS orbits are generated based on one year of tracking data from the global IGS network and involving the box-wing model implemented into the Bernese GPS Software. The processing scheme was derived from the one used at the Center for Orbit Determination in Europe (CODE). The resulting satellite orbits are compared with CODE Final Orbits and validated using SLR (Satellite Laser Ranging) tracking data. Additionally, in the case of GPS satellites, the box-wing model and the obtained optical properties are compared directly with a priori models (e.g. ROCK), which deal with the direct solar radiation impacting the satellites.

The use of a multidimensional space for fusion candidate representation in a maritime domain awareness application

NASA Astrophysics Data System (ADS)

Lefebvre, Eric; Helleur, Christopher; Kashyap, Nathan

2008-03-01

Maritime surveillance of coastal regions requires operational staff to integrate a large amount of information from a variety of military and civilian sources. The diverse nature of the information sources makes complete automation difficult. The volume of vessels tracked and the number of sources makes it difficult for the limited operation centre staff to fuse all the information manually within a reasonable timeframe. In this paper, a conceptual decision space is proposed to provide a framework for automating the process of operators integrating the sources needed to maintain Maritime Domain Awareness. The decision space contains all potential pairs of ship tracks that are candidates for fusion. The location of the candidate pairs in this defined space depends on the value of the parameters used to make a decision. In the application presented, three independent parameters are used: the source detection efficiency, the geo-feasibility, and the track quality. One of three decisions is applied to each candidate track pair based on these three parameters: 1. to accept the fusion, in which case tracks are fused in one track, 2. to reject the fusion, in which case the candidate track pair is removed from the list of potential fusion, and 3. to defer the fusion, in which case no fusion occurs but the candidate track pair remains in the list of potential fusion until sufficient information is provided. This paper demonstrates in an operational setting how a proposed conceptual space is used to optimize the different thresholds for automatic fusion decision while minimizing the list of unresolved cases when the decision is left to the operator.

"Usability of data integration and visualization software for multidisciplinary pediatric intensive care: a human factors approach to assessing technology".

PubMed

Lin, Ying Ling; Guerguerian, Anne-Marie; Tomasi, Jessica; Laussen, Peter; Trbovich, Patricia

2017-08-14

Intensive care clinicians use several sources of data in order to inform decision-making. We set out to evaluate a new interactive data integration platform called T3™ made available for pediatric intensive care. Three primary functions are supported: tracking of physiologic signals, displaying trajectory, and triggering decisions, by highlighting data or estimating risk of patient instability. We designed a human factors study to identify interface usability issues, to measure ease of use, and to describe interface features that may enable or hinder clinical tasks. Twenty-two participants, consisting of bedside intensive care physicians, nurses, and respiratory therapists, tested the T3™ interface in a simulation laboratory setting. Twenty tasks were performed with a true-to-setting, fully functional, prototype, populated with physiological and therapeutic intervention patient data. Primary data visualization was time series and secondary visualizations were: 1) shading out-of-target values, 2) mini-trends with exaggerated maxima and minima (sparklines), and 3) bar graph of a 16-parameter indicator. Task completion was video recorded and assessed using a use error rating scale. Usability issues were classified in the context of task and type of clinician. A severity rating scale was used to rate potential clinical impact of usability issues. Time series supported tracking a single parameter but partially supported determining patient trajectory using multiple parameters. Visual pattern overload was observed with multiple parameter data streams. Automated data processing using shading and sparklines was often ignored but the 16-parameter data reduction algorithm, displayed as a persistent bar graph, was visually intuitive. However, by selecting or automatically processing data, triggering aids distorted the raw data that clinicians use regularly. Consequently, clinicians could not rely on new data representations because they did not know how they were established or derived. Usability issues, observed through contextual use, provided directions for tangible design improvements of data integration software that may lessen use errors and promote safe use. Data-driven decision making can benefit from iterative interface redesign involving clinician-users in simulated environments. This study is a first step in understanding how software can support clinicians' decision making with integrated continuous monitoring data. Importantly, testing of similar platforms by all the different disciplines who may become clinician users is a fundamental step necessary to understand the impact on clinical outcomes of decision aids.

Sensitivity of Space Station alpha joint robust controller to structural modal parameter variations

NASA Technical Reports Server (NTRS)

Kumar, Renjith R.; Cooper, Paul A.; Lim, Tae W.

1991-01-01

The photovoltaic array sun tracking control system of Space Station Freedom is described. A synthesis procedure for determining optimized values of the design variables of the control system is developed using a constrained optimization technique. The synthesis is performed to provide a given level of stability margin, to achieve the most responsive tracking performance, and to meet other design requirements. Performance of the baseline design, which is synthesized using predicted structural characteristics, is discussed and the sensitivity of the stability margin is examined for variations of the frequencies, mode shapes and damping ratios of dominant structural modes. The design provides enough robustness to tolerate a sizeable error in the predicted modal parameters. A study was made of the sensitivity of performance indicators as the modal parameters of the dominant modes vary. The design variables are resynthesized for varying modal parameters in order to achieve the most responsive tracking performance while satisfying the design requirements. This procedure of reoptimization design parameters would be useful in improving the control system performance if accurate model data are provided.

Impact analysis of the transponder time delay on radio-tracking observables

NASA Astrophysics Data System (ADS)

Bertone, Stefano; Le Poncin-Lafitte, Christophe; Rosenblatt, Pascal; Lainey, Valéry; Marty, Jean-Charles; Angonin, Marie-Christine

2018-01-01

Accurate tracking of probes is one of the key points of space exploration. Range and Doppler techniques are the most commonly used. In this paper we analyze the impact of the transponder delay, i . e . the processing time between reception and re-emission of a two-way tracking link at the satellite, on tracking observables and on spacecraft orbits. We show that this term, only partially accounted for in the standard formulation of computed space observables, can actually be relevant for future missions with high nominal tracking accuracies or for the re-processing of old missions. We present several applications of our formulation to Earth flybys, the NASA GRAIL and the ESA BepiColombo missions.

Information content in reflected signals during GPS Radio Occultation observations

NASA Astrophysics Data System (ADS)

Aparicio, Josep M.; Cardellach, Estel; Rodríguez, Hilda

2018-04-01

The possibility of extracting useful information about the state of the lower troposphere from the surface reflections that are often detected during GPS radio occultations (GPSRO) is explored. The clarity of the reflection is quantified, and can be related to properties of the surface and the low troposphere. The reflected signal is often clear enough to show good phase coherence, and can be tracked and processed as an extension of direct non-reflected GPSRO atmospheric profiles. A profile of bending angle vs. impact parameter can be obtained for these reflected signals, characterized by impact parameters that are below the apparent horizon, and that is a continuation at low altitude of the standard non-reflected bending angle profile. If there were no reflection, these would correspond to tangent altitudes below the local surface, and in particular below the local mean sea level. A forward operator is presented, for the evaluation of the bending angle of reflected GPSRO signals, given atmospheric properties as described by a numerical weather prediction system. The operator is an extension, at lower impact parameters, of standard bending angle operators, and reproduces both the direct and reflected sections of the measured profile. It can be applied to the assimilation of the reflected section of the profile as supplementary data to the direct section. Although the principle is also applicable over land, this paper is focused on ocean cases, where the topographic height of the reflecting surface, the sea level, is better known a priori.

Dealing with the time-varying parameter problem of robot manipulators performing path tracking tasks

NASA Technical Reports Server (NTRS)

Song, Y. D.; Middleton, R. H.

1992-01-01

Many robotic applications involve time-varying payloads during the operation of the robot. It is therefore of interest to consider control schemes that deal with time-varying parameters. Using the properties of the element by element (or Hadarmad) product of matrices, we obtain the robot dynamics in parameter-isolated form, from which a new control scheme is developed. The controller proposed yields zero asymptotic tracking errors when applied to robotic systems with time-varying parameters by using a switching type control law. The results obtained are global in the initial state of the robot, and can be applied to rapidly varying systems.

On-Line Identification of Simulation Examples for Forgetting Methods to Track Time Varying Parameters Using the Alternative Covariance Matrix in Matlab

NASA Astrophysics Data System (ADS)

Vachálek, Ján

2011-12-01

The paper compares the abilities of forgetting methods to track time varying parameters of two different simulated models with different types of excitation. The observed parameters in the simulations are the integral sum of the Euclidean norm, deviation of the parameter estimates from their true values and a selected band prediction error count. As supplementary information, we observe the eigenvalues of the covariance matrix. In the paper we used a modified method of Regularized Exponential Forgetting with Alternative Covariance Matrix (REFACM) along with Directional Forgetting (DF) and three standard regularized methods.

Discovery of Non-random Spatial Distribution of Impacts in the Stardust Cometary Collector

NASA Technical Reports Server (NTRS)

Horz, Friedrich; Westphal, Andrew J.; Gainsforth, Zack; Borg, Janet; Djouadi, Zahia; Bridges, John; Franchi, Ian; Brownlee, Donald E.; Cheng. Andrew F.; Clark, Benton C.;

Influence of the track quality and of the properties of the wheel-rail rolling contact on vehicle dynamics

NASA Astrophysics Data System (ADS)

Suarez, Berta; Felez, Jesus; Lozano, José Antonio; Rodriguez, Pablo

2013-02-01

This work describes an analytical approach to determine what degree of accuracy is required in the definition of the rail vehicle models used for dynamic simulations. This way it would be possible to know in advance how the results of simulations may be altered due to the existence of errors in the creation of rolling stock models, whilst also identifying their critical parameters. This would make it possible to maximise the time available to enhance dynamic analysis and focus efforts on factors that are strictly necessary. In particular, the parameters related both to the track quality and to the rolling contact were considered in this study. With this aim, a sensitivity analysis was performed to assess their influence on the vehicle dynamic behaviour. To do this, 72 dynamic simulations were performed modifying, one at a time, the track quality, the wheel-rail friction coefficient and the equivalent conicity of both new and worn wheels. Three values were assigned to each parameter, and two wear states were considered for each type of wheel, one for new wheels and another one for reprofiled wheels. After processing the results of these simulations, it was concluded that all the parameters considered show very high influence, though the friction coefficient shows the highest influence. Therefore, it is recommended to undertake any future simulation job with measured track geometry and track irregularities, measured wheel profiles and normative values of the wheel-rail friction coefficient.

A mathematical model for computer image tracking.

PubMed

Legters, G R; Young, T Y

1982-06-01

A mathematical model using an operator formulation for a moving object in a sequence of images is presented. Time-varying translation and rotation operators are derived to describe the motion. A variational estimation algorithm is developed to track the dynamic parameters of the operators. The occlusion problem is alleviated by using a predictive Kalman filter to keep the tracking on course during severe occlusion. The tracking algorithm (variational estimation in conjunction with Kalman filter) is implemented to track moving objects with occasional occlusion in computer-simulated binary images.

Systematic investigations of intense convective precipitation events on European scale based on radar- and lightning-cell tracking

NASA Astrophysics Data System (ADS)

Tüchler, Lukas; Meyer, Vera

2013-04-01

The new radar-data and lightning-data based automatic cell identification, tracking and nowcasting tool A-TNT (Austrian Thunderstorm Nowcasting Tool), which has been developed at ZAMG, has been applied to investigate the appearance of thunderstorms at Europe scale. Based on the ec-TRAM-method [1], the algorithm identifies and monitors regions of intense precipitation and lightning activity separately by analyzing sequential two-dimensional intensity maps of radar precipitation rate or lightning densities, respectively. Each data source is processed by a stand-alone identification, tracking and nowcasting procedure. The two tracking results are combined to a "main" cell in a final step. This approach allows that the output derived from the two data sources complement each other giving a more comprehensive picture about the current storm situation. So it is possible to distinguish between pure precipitation cells and thunderstorms, to observe regions, where one data source is not or poorly available, and to compensate for occasional data failures. Consequently, the combined cell-tracks are expected to be more consistent and the cell-tracking more robust. Input data for radar-cell tracking on European Scale is the OPERA radar-composite, which is provided every 15 minutes on a 2 km x 2 km grid, indicating the location and intensity of precipitation over Europe. For the lightning-cell tracking, the lightning-detection data of the EUCLID network is mapped on the OPERA grid. Every five minutes, flash density maps with recorded strokes are created and analyzed. This study will present a detailed investigation of the quality of the identification and tracking results using radar and lightning data. The improvements concerning the robustness and reliability of the cell tracking achieved by combining both data sources will be shown. Analyses about cell tracks and selected storm parameters like frequency, longevity and area will give insight into occurrence, appearance and impact of different severe precipitation events. These studies are performed to support the project HAREN (Hazard Assessment based on Rainfall European Nowcasts, funded by the EC Directorate General for Humanitarian Aid and Civil Protection), which has the objective to improve warnings for hazards induced by precipitation at local scale all over Europe. REFERENCES: [1] Meyer, V. K., H. Höller, and H. D. Betz 2012: Automated thunderstorm tracking and nowcasting: utilization of three-dimensional lightning and radar data. Manuscript accepted for publication in ACPD.

The Flight Track Noise Impact Model

NASA Technical Reports Server (NTRS)

Burn, Melissa; Carey, Jeffrey; Czech, Joseph; Wingrove, Earl R., III

1997-01-01

To meet its objective of assisting the U.S. aviation industry with the technological challenges of the future, NASA must identify research areas that have the greatest potential for improving the operation of the air transportation system. To accomplish this, NASA is building an Aviation System Analysis Capability (ASAC). The Flight Track Noise Impact Model (FTNIM) has been developed as part of the ASAC. Its primary purpose is to enable users to examine the impact that quieter aircraft technologies and/or operations might have on air carrier operating efficiency at any one of 8 selected U.S. airports. The analyst selects an airport and case year for study, chooses a set of flight tracks for use in the case, and has the option of reducing the noise of the aircraft by 3, 6, or 10 decibels. Two sets of flight tracks are available for each airport: one that represents actual current conditions, including noise abatement tracks, which avoid flying over noise-sensitive areas; and a second set that offers more efficient routing. FTNIM computes the resultant noise impact and the time and distance saved for each operation on the more efficient, alternate tracks. Noise impact is characterized in three ways: the size of the noise contour footprint, the number of people living within the contours, and the number of homes located in the same contours. Distance and time savings are calculated by comparing the noise abatement flight path length to the more efficient alternate routing.

Passive bloodstains: from an impact energy to a final dried pattern

NASA Astrophysics Data System (ADS)

Smith, Fiona; Brutin, David

2016-11-01

Tracking down the origin of a blood droplet present on a crime scene has become of major importance in bloodstain pattern analysis. Passive bloodstains are not yet well understood. Accordingly the purpose of this research is to provide new tools to forensic investigators in the analysis of bloodstains arising from blood droplets dripping naturally. The study aims to understand the link between the final dried pattern of a passive bloodstain and its impact energy. Currently no such tool exists, and no correlation has yet been proven. This research was therefore focusing on a new parameter, the thicker outer rim observed on the dried final pattern. To do so, we created several passive bloodstains with different impact energies. A correlation was highlighted between the inner diameter, the maximum spreading diameter, the initial diameter of a blood droplet and its impact energy. This correlation shows how the drying mechanism of a blood droplet is influenced by its impact energy as it alters the red blood cells dispersion inside the droplet. The biological deposit and the final dried pattern are subsequently modified. ANR funded project: D-Blood Project.

Artificial lunar impact craters: Four new identifications, part I

NASA Technical Reports Server (NTRS)

Whitaker, E. A.

1972-01-01

The Apollo 16 panoramic camera photographed the impact locations of the Ranger 7 and 9 spacecraft and the S-4B stage of the Apollo 14 Saturn launch vehicle. Identification of the Ranger craters was very simple because each photographed its target point before impact. Identification of the S-4B impact crater proved to be a simple matter because the impact location, as derived from earth-based tracking, displayed a prominent and unique system of mixed light and dark rays. By using the criterion of a dark ray pattern, a reexamination of the Apollo 14 500 mm Hasselblad sequence taken of the Apollo 13 S-4B impact area was made. This examination quickly led to the discovery of the ray system and the impact crater. The study of artificial lunar impact craters, ejecta blankets, and ray systems provides the long-needed link between the various experimental terrestrial impact and explosion craters, and the naturally occurring impact craters on the moon. This elementary study shows that lunar impact crater diameters are closely predictable from a knowledge of the energies involved, at least in the size range considered, and suggests that parameters, such as velocity, may have a profound effect on crater morphology and ejecta blanket albedo.

Dynamic properties of a dirt and a synthetic equine racetrack surface measured by a track-testing device.

PubMed

Setterbo, J J; Fyhrie, P B; Hubbard, M; Upadhyaya, S K; Stover, S M

2013-01-01

Racetrack surface is a risk factor for Thoroughbred racehorse injury and death that can be engineered and managed. To investigate the relationship between surface and injury, the mechanical behaviour of dirt and synthetic track surfaces must be quantified. To compare dynamic properties of a dirt and a synthetic surface in situ using a track-testing device designed to simulate equine hoof impact; and to determine the effects of impact velocity, impact angle and repeated impact on dynamic surface behaviour. A track-testing device measured force and displacement during impact into a dirt and a synthetic surface at 3 impact velocities (1.91, 2.30, 2.63 m/s), 2 impact angles (0°, 20° from vertical), and 2 consecutive impacts (initial, repeat). Surfaces were measured at 3 locations/day for 3 days. The effects of surface type, impact velocity, impact angle and impact number on dynamic surface properties were assessed using analysis of variance. Synthetic surface maximum forces, load rates and stiffnesses were 37-67% of dirt surface values. Surfaces were less stiff with lower impact velocities, angled impacts and initial impacts. The magnitude of differences between dirt and synthetic surfaces increased for repeat impacts and higher impact velocities. The synthetic surface was generally softer than the dirt surface. Greatly increased hardness for repeat impacts corroborates the importance of maintenance. Results at different impact velocities suggest that surface differences will persist at higher impact velocities. For both surfaces it is clearly important to prevent horse exposure to precompacted surfaces, particularly during high-speed training when the surface has already been trampled. These data should be useful in coordinating racetrack surface management with racehorse training to prevent injuries. © 2012 EVJ Ltd.

Decorrelation Times of Photospheric Fields and Flows

NASA Technical Reports Server (NTRS)

Welsch, B. T.; Kusano, K.; Yamamoto, T. T.; Muglach, K.

2012-01-01

We use autocorrelation to investigate evolution in flow fields inferred by applying Fourier Local Correlation Tracking (FLCT) to a sequence of high-resolution (0.3 "), high-cadence (approx = 2 min) line-of-sight magnetograms of NOAA active region (AR) 10930 recorded by the Narrowband Filter Imager (NFI) of the Solar Optical Telescope (SOT) aboard the Hinode satellite over 12 - 13 December 2006. To baseline the timescales of flow evolution, we also autocorrelated the magnetograms, at several spatial binnings, to characterize the lifetimes of active region magnetic structures versus spatial scale. Autocorrelation of flow maps can be used to optimize tracking parameters, to understand tracking algorithms f susceptibility to noise, and to estimate flow lifetimes. Tracking parameters varied include: time interval Delta t between magnetogram pairs tracked, spatial binning applied to the magnetograms, and windowing parameter sigma used in FLCT. Flow structures vary over a range of spatial and temporal scales (including unresolved scales), so tracked flows represent a local average of the flow over a particular range of space and time. We define flow lifetime to be the flow decorrelation time, tau . For Delta t > tau, tracking results represent the average velocity over one or more flow lifetimes. We analyze lifetimes of flow components, divergences, and curls as functions of magnetic field strength and spatial scale. We find a significant trend of increasing lifetimes of flow components, divergences, and curls with field strength, consistent with Lorentz forces partially governing flows in the active photosphere, as well as strong trends of increasing flow lifetime and decreasing magnitudes with increases in both spatial scale and Delta t.

System health monitoring using multiple-model adaptive estimation techniques

NASA Astrophysics Data System (ADS)

Sifford, Stanley Ryan

Monitoring system health for fault detection and diagnosis by tracking system parameters concurrently with state estimates is approached using a new multiple-model adaptive estimation (MMAE) method. This novel method is called GRid-based Adaptive Parameter Estimation (GRAPE). GRAPE expands existing MMAE methods by using new techniques to sample the parameter space. GRAPE expands on MMAE with the hypothesis that sample models can be applied and resampled without relying on a predefined set of models. GRAPE is initially implemented in a linear framework using Kalman filter models. A more generalized GRAPE formulation is presented using extended Kalman filter (EKF) models to represent nonlinear systems. GRAPE can handle both time invariant and time varying systems as it is designed to track parameter changes. Two techniques are presented to generate parameter samples for the parallel filter models. The first approach is called selected grid-based stratification (SGBS). SGBS divides the parameter space into equally spaced strata. The second approach uses Latin Hypercube Sampling (LHS) to determine the parameter locations and minimize the total number of required models. LHS is particularly useful when the parameter dimensions grow. Adding more parameters does not require the model count to increase for LHS. Each resample is independent of the prior sample set other than the location of the parameter estimate. SGBS and LHS can be used for both the initial sample and subsequent resamples. Furthermore, resamples are not required to use the same technique. Both techniques are demonstrated for both linear and nonlinear frameworks. The GRAPE framework further formalizes the parameter tracking process through a general approach for nonlinear systems. These additional methods allow GRAPE to either narrow the focus to converged values within a parameter range or expand the range in the appropriate direction to track the parameters outside the current parameter range boundary. Customizable rules define the specific resample behavior when the GRAPE parameter estimates converge. Convergence itself is determined from the derivatives of the parameter estimates using a simple moving average window to filter out noise. The system can be tuned to match the desired performance goals by making adjustments to parameters such as the sample size, convergence criteria, resample criteria, initial sampling method, resampling method, confidence in prior sample covariances, sample delay, and others.

Tracking Systems for Virtual Rehabilitation: Objective Performance vs. Subjective Experience. A Practical Scenario

PubMed Central

Lloréns, Roberto; Noé, Enrique; Naranjo, Valery; Borrego, Adrián; Latorre, Jorge; Alcañiz, Mariano

2015-01-01

Motion tracking systems are commonly used in virtual reality-based interventions to detect movements in the real world and transfer them to the virtual environment. There are different tracking solutions based on different physical principles, which mainly define their performance parameters. However, special requirements have to be considered for rehabilitation purposes. This paper studies and compares the accuracy and jitter of three tracking solutions (optical, electromagnetic, and skeleton tracking) in a practical scenario and analyzes the subjective perceptions of 19 healthy subjects, 22 stroke survivors, and 14 physical therapists. The optical tracking system provided the best accuracy (1.074 ± 0.417 cm) while the electromagnetic device provided the most inaccurate results (11.027 ± 2.364 cm). However, this tracking solution provided the best jitter values (0.324 ± 0.093 cm), in contrast to the skeleton tracking, which had the worst results (1.522 ± 0.858 cm). Healthy individuals and professionals preferred the skeleton tracking solution rather than the optical and electromagnetic solution (in that order). Individuals with stroke chose the optical solution over the other options. Our results show that subjective perceptions and preferences are far from being constant among different populations, thus suggesting that these considerations, together with the performance parameters, should be also taken into account when designing a rehabilitation system. PMID:25808765

Electroweak production of the top quark in the Run II of the D0 experiment (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clement, Benoit

The work exposed in this thesis deals with the search for electroweak production of top quark (single top) in proton-antiproton collisions at √s = 1.96 TeV. This production mode has not been observed yet. Analyzed data have been collected during the Run II of the D0 experiment at the Fermilab Tevatron collider. These data correspond to an integrated luminosity of 370 pb -1. In the Standard Model, the decay of a top quark always produce a high momentum bottom quark. Therefore bottom quark jets identification plays a major role in this analysis. The large lifetime of b hadrons and themore » subsequent large impact parameters relative to the interaction vertex of charged particle tracks are used to tag bottom quark jets. Impact parameters of tracks attached to a jet are converted into the probability for the jet to originate from the primary vertex. This algorithm has a 45% tagging efficiency for a 0.5% mistag rate. Two processes (s and t channels) dominate single top production with slightly different final states. The searched signature consists in 2 to 4 jets with at least one bottom quark jet, one charged lepton (electron or muon) and missing energy accounting for a neutrino. This final state is background dominated and multivariate techniques are needed to separate the signal from the two main backgrounds: associated production of a W boson and jets and top quarks pair production. The achieved sensitivity is not enough to reach observation and we computed upper limits at the 95% confidence level at 5 pb (s-channel) and 4.3 pb (t-channel) on single top production cross-sections.« less

The Simpsons program 6-D phase space tracking with acceleration

NASA Astrophysics Data System (ADS)

Machida, S.

1993-12-01

A particle tracking code, Simpsons, in 6-D phase space including energy ramping has been developed to model proton synchrotrons and storage rings. We take time as the independent variable to change machine parameters and diagnose beam quality in a quite similar way as real machines, unlike existing tracking codes for synchrotrons which advance a particle element by element. Arbitrary energy ramping and rf voltage curves as a function of time are read as an input file for defining a machine cycle. The code is used to study beam dynamics with time dependent parameters. Some of the examples from simulations of the Superconducting Super Collider (SSC) boosters are shown.

Collision of Dual Aggregates (CODA): Experimental observations of low-velocity collisions

NASA Astrophysics Data System (ADS)

Jorges, Jeffery; Dove, Adrienne; Colwell, Josh E.

2016-10-01

Low-velocity collisions are one of the driving factors that determine the particle size distribution and particle size evolution in planetary ring systems and in the early stages of planet formation. Collisions of sub-micron to decimeter-sized objects may result in particle growth by accretion, rebounding, or erosive processes that result in the production of additional smaller particles. Numerical simulations of these systems are limited by a need to understand these collisional parameters over a range of conditions. We present the results of a sequence of laboratory experiments designed to explore collisions over a range of parameter space . We are able to observe low-velocity collisions by conducting experiments in vacuum chambers in our 0.8-sec drop tower apparatus. Initial experiments utilize a variety of impacting spheres, including glass, Teflon, aluminum, stainless steel, and brass. These spheres are either used in their natural state or are "mantled" - coated with a few-mm thick layer of a cohesive powder. A high-speed, high-resolution video camera is used to record the motion of the colliding bodies. We track the particles to determine impactor speeds before and after collision, the impact parameter, and the collisional outcome. In the case of the mantled impactors, we can assess how much rotation is generated by the collision and estimate how much powder is released (i.e. how much mass is lost) due to the collision. We also determine how the coefficient of restitution varies as a function of material type, morphology, and impact velocity. With impact velocities ranging from about 20-100 cm/s we observe that mantling of particles significantly reduces their coefficients of restitution, but we see basically no dependence of the coefficient of restitution on the impact velocity, impact parameter, or system mass. The results of this study will contribute to a better empirical model of collisional outcomes that will be refined with numerical simulation of the experiment to improve our understanding of the collisional evolution of ring systems and early planet formation.

Application of maximum entropy to statistical inference for inversion of data from a single track segment.

PubMed

Stotts, Steven A; Koch, Robert A

2017-08-01

In this paper an approach is presented to estimate the constraint required to apply maximum entropy (ME) for statistical inference with underwater acoustic data from a single track segment. Previous algorithms for estimating the ME constraint require multiple source track segments to determine the constraint. The approach is relevant for addressing model mismatch effects, i.e., inaccuracies in parameter values determined from inversions because the propagation model does not account for all acoustic processes that contribute to the measured data. One effect of model mismatch is that the lowest cost inversion solution may be well outside a relatively well-known parameter value's uncertainty interval (prior), e.g., source speed from track reconstruction or towed source levels. The approach requires, for some particular parameter value, the ME constraint to produce an inferred uncertainty interval that encompasses the prior. Motivating this approach is the hypothesis that the proposed constraint determination procedure would produce a posterior probability density that accounts for the effect of model mismatch on inferred values of other inversion parameters for which the priors might be quite broad. Applications to both measured and simulated data are presented for model mismatch that produces minimum cost solutions either inside or outside some priors.

Comparison of particle-tracking and lumped-parameter age-distribution models for evaluating vulnerability of production wells to contamination

USGS Publications Warehouse

Eberts, S.M.; Böhlke, J.K.; Kauffman, L.J.; Jurgens, B.C.

2012-01-01

Environmental age tracers have been used in various ways to help assess vulnerability of drinking-water production wells to contamination. The most appropriate approach will depend on the information that is available and that which is desired. To understand how the well will respond to changing nonpoint-source contaminant inputs at the water table, some representation of the distribution of groundwater ages in the well is needed. Such information for production wells is sparse and difficult to obtain, especially in areas lacking detailed field studies. In this study, age distributions derived from detailed groundwater-flow models with advective particle tracking were compared with those generated from lumped-parameter models to examine conditions in which estimates from simpler, less resource-intensive lumped-parameter models could be used in place of estimates from particle-tracking models. In each of four contrasting hydrogeologic settings in the USA, particle-tracking and lumped-parameter models yielded roughly similar age distributions and largely indistinguishable contaminant trends when based on similar conceptual models and calibrated to similar tracer data. Although model calibrations and predictions were variably affected by tracer limitations and conceptual ambiguities, results illustrated the importance of full age distributions, rather than apparent tracer ages or model mean ages, for trend analysis and forecasting.

Identification of seismic activity sources on the subsatellite track by ionospheric plasma disturbances detected with the Sich-2 onboard probes

NASA Astrophysics Data System (ADS)

Shuvalov, Valentin A.; Lazuchenkov, Dmitry N.; Gorev, Nikolai B.; Kochubei, Galina S.

2018-01-01

Using a cylindrical Langmuir probe and the authors' proprietary two-channel pressure transducer, ionospheric plasma parameter distributions along the orbit of the Sich-2 satellite (Ukraine, 2011-2012) were measured. This paper is concerned with identifying the space-time location of ionospheric plasma disturbance sources, including the epicenters of actual earthquakes (before or during the satellite flyover) and incipient earthquakes on the subsatellite track, from the measured distributions of the electron density and temperature and the neutral particle temperature along the satellite orbit. To do this, the measured ionospheric plasma parameter distributions are connected to the coordinates on the subsatellite track. It is shown that local disturbances in the electron density and temperature and neutral particle temperature distributions in the satellite orbit in the ionosphere may serve as indicators of seismic activity on the subsatellite track. The epicenters of incipient earthquakes may be set off from other plasma parameter disturbance sources associated with seismic activity using information provided by special monitoring and survey centers that monitor the current seismic situation.

Adaptive angular-velocity Vold-Kalman filter order tracking - Theoretical basis, numerical implementation and parameter investigation

NASA Astrophysics Data System (ADS)

Pan, M.-Ch.; Chu, W.-Ch.; Le, Duc-Do

2016-12-01

The paper presents an alternative Vold-Kalman filter order tracking (VKF_OT) method, i.e. adaptive angular-velocity VKF_OT technique, to extract and characterize order components in an adaptive manner for the condition monitoring and fault diagnosis of rotary machinery. The order/spectral waveforms to be tracked can be recursively solved by using Kalman filter based on the one-step state prediction. The paper comprises theoretical derivation of computation scheme, numerical implementation, and parameter investigation. Comparisons of the adaptive VKF_OT scheme with two other ones are performed through processing synthetic signals of designated order components. Processing parameters such as the weighting factor and the correlation matrix of process noise, and data conditions like the sampling frequency, which influence tracking behavior, are explored. The merits such as adaptive processing nature and computation efficiency brought by the proposed scheme are addressed although the computation was performed in off-line conditions. The proposed scheme can simultaneously extract multiple spectral components, and effectively decouple close and crossing orders associated with multi-axial reference rotating speeds.

Steering Dynamics of Tilting Narrow Track Vehicle with Passive Front Wheel Design

NASA Astrophysics Data System (ADS)

TAN, Jeffrey Too Chuan; ARAKAWA, Hiroki; SUDA, Yoshihiro

2016-09-01

In recent years, narrow track vehicle has been emerged as a potential candidate for the next generation of urban transportation system, which is greener and space effective. Vehicle body tilting has been a symbolic characteristic of such vehicle, with the purpose to maintain its stability with the narrow track body. However, the coordination between active steering and vehicle tilting requires considerable driving skill in order to achieve effective stability. In this work, we propose an alternative steering method with a passive front wheel that mechanically follows the vehicle body tilting. The objective of this paper is to investigate the steering dynamics of the vehicle under various design parameters of the passive front wheel. Modeling of a three-wheel tilting narrow track vehicle and multibody dynamics simulations were conducted to study the effects of two important front wheel design parameters, i.e. caster angle and trail toward the vehicle steering dynamics in steering response time, turning radius, steering stability and resiliency towards external disturbance. From the results of the simulation studies, we have verified the relationships of these two front wheel design parameters toward the vehicle steering dynamics.

A data processing method based on tracking light spot for the laser differential confocal component parameters measurement system

NASA Astrophysics Data System (ADS)

Shao, Rongjun; Qiu, Lirong; Yang, Jiamiao; Zhao, Weiqian; Zhang, Xin

2013-12-01

We have proposed the component parameters measuring method based on the differential confocal focusing theory. In order to improve the positioning precision of the laser differential confocal component parameters measurement system (LDDCPMS), the paper provides a data processing method based on tracking light spot. To reduce the error caused by the light point moving in collecting the axial intensity signal, the image centroiding algorithm is used to find and track the center of Airy disk of the images collected by the laser differential confocal system. For weakening the influence of higher harmonic noises during the measurement, Gaussian filter is used to process the axial intensity signal. Ultimately the zero point corresponding to the focus of the objective in a differential confocal system is achieved by linear fitting for the differential confocal axial intensity data. Preliminary experiments indicate that the method based on tracking light spot can accurately collect the axial intensity response signal of the virtual pinhole, and improve the anti-interference ability of system. Thus it improves the system positioning accuracy.

Single Tracking Location Acoustic Radiation Force Impulse Viscoelasticity Estimation (STL-VE): A Method for Measuring Tissue Viscoelastic Parameters

PubMed Central

Langdon, Jonathan H; Elegbe, Etana; McAleavey, Stephen A

2015-01-01

Single Tracking Location (STL) Shear wave Elasticity Imaging (SWEI) is a method for detecting elastic differences between tissues. It has the advantage of intrinsic speckle bias suppression compared to Multiple Tracking Location (MTL) variants of SWEI. However, the assumption of a linear model leads to an overestimation of the shear modulus in viscoelastic media. A new reconstruction technique denoted Single Tracking Location Viscosity Estimation (STL-VE) is introduced to correct for this overestimation. This technique utilizes the same raw data generated in STL-SWEI imaging. Here, the STL-VE technique is developed by way of a Maximum Likelihood Estimation (MLE) for general viscoelastic materials. The method is then implemented for the particular case of the Kelvin-Voigt Model. Using simulation data, the STL-VE technique is demonstrated and the performance of the estimator is characterized. Finally, the STL-VE method is used to estimate the viscoelastic parameters of ex-vivo bovine liver. We find good agreement between the STL-VE results and the simulation parameters as well as between the liver shear wave data and the modeled data fit. PMID:26168170

Developing a particle tracking surrogate model to improve inversion of ground water - Surface water models

NASA Astrophysics Data System (ADS)

Cousquer, Yohann; Pryet, Alexandre; Atteia, Olivier; Ferré, Ty P. A.; Delbart, Célestine; Valois, Rémi; Dupuy, Alain

2018-03-01

The inverse problem of groundwater models is often ill-posed and model parameters are likely to be poorly constrained. Identifiability is improved if diverse data types are used for parameter estimation. However, some models, including detailed solute transport models, are further limited by prohibitive computation times. This often precludes the use of concentration data for parameter estimation, even if those data are available. In the case of surface water-groundwater (SW-GW) models, concentration data can provide SW-GW mixing ratios, which efficiently constrain the estimate of exchange flow, but are rarely used. We propose to reduce computational limits by simulating SW-GW exchange at a sink (well or drain) based on particle tracking under steady state flow conditions. Particle tracking is used to simulate advective transport. A comparison between the particle tracking surrogate model and an advective-dispersive model shows that dispersion can often be neglected when the mixing ratio is computed for a sink, allowing for use of the particle tracking surrogate model. The surrogate model was implemented to solve the inverse problem for a real SW-GW transport problem with heads and concentrations combined in a weighted hybrid objective function. The resulting inversion showed markedly reduced uncertainty in the transmissivity field compared to calibration on head data alone.

Operational Improvements From the In-Trail Procedure in the North Atlantic Organized Track System

NASA Technical Reports Server (NTRS)

Chartrand, Ryan C.; Bussink, Frank J. L.; Graff, Thomas J.; Murdoch, Jennifer L.; Jones, Kenneth M.

2008-01-01

This paper explains the computerized batch processing experiment examining the operational impacts of the introduction of Automatic Dependent Surveillance-Broadcast (ADS-B) equipment and the In-Trail Procedure (ITP) to the North Atlantic Organized Track System (NATOTS). This experiment was conducted using the Traffic Manager (TMX), a desktop simulation capable of simulating airspace environments and aircraft operations. ADS-B equipment can enable the use of new ground and airborne procedures, such as the ITP. The ITP is among the first of these new procedures, which will make use of improved situation awareness in the local surrounding airspace of ADS-B equipped aircraft to enable more efficient oceanic flight level changes. The data collected were analyzed with respect to multiple operationally relevant parameters including fuel burn, request approval rates, and the distribution of fuel savings. This experiment showed that through the use of ADS-B or ADS-B and the ITP that operational improvements and benefits could be achieved.

Operational Improvements From Using the In-Trail Procedure in the North Atlantic Organized Track System

NASA Technical Reports Server (NTRS)

Chartrand, Ryan C.; Bussink, Frank J.; Graff, Thomas J.; Jones, Kenneth M.

2009-01-01

This paper explains the computerized batch processing experiment examining the operational impacts of the introduction of Automatic Dependent Surveillance-Broadcast (ADS-B) equipment and the In-Trail Procedure (ITP) to the North Atlantic Organized Track System. This experiment was conducted using the Traffic Manager (TMX), a desktop simulation capable of simulating airspace environments and aircraft operations. ADS-B equipment can enable the use of new ground and airborne procedures, such as the ITP. ITP is among the first of these new procedures, which will make use of improved situation awareness in the local surrounding airspace of ADS-B equipped aircraft to enable more efficient oceanic flight level changes. The collected data were analyzed with respect to multiple operationally relevant parameters including fuel burn, request approval rates, and the distribution of fuel savings. This experiment showed that through the use of ADS-B or ADS-B and the ITP that operational improvements and benefits could be achieved.

Tracking initially unresolved thrusting objects in 3D using a single stationary optical sensor

NASA Astrophysics Data System (ADS)

Lu, Qin; Bar-Shalom, Yaakov; Willett, Peter; Granström, Karl; Ben-Dov, R.; Milgrom, B.

2017-05-01

This paper considers the problem of estimating the 3D states of a salvo of thrusting/ballistic endo-atmospheric objects using 2D Cartesian measurements from the focal plane array (FPA) of a single fixed optical sensor. Since the initial separations in the FPA are smaller than the resolution of the sensor, this results in merged measurements in the FPA, compounding the usual false-alarm and missed-detection uncertainty. We present a two-step methodology. First, we assume a Wiener process acceleration (WPA) model for the motion of the images of the projectiles in the optical sensor's FPA. We model the merged measurements with increased variance, and thence employ a multi-Bernoulli (MB) filter using the 2D measurements in the FPA. Second, using the set of associated measurements for each confirmed MB track, we formulate a parameter estimation problem, whose maximum likelihood estimate can be obtained via numerical search and can be used for impact point prediction. Simulation results illustrate the performance of the proposed method.

Machine learning assembly landscapes from particle tracking data.

PubMed

Long, Andrew W; Zhang, Jie; Granick, Steve; Ferguson, Andrew L

2015-11-07

Bottom-up self-assembly offers a powerful route for the fabrication of novel structural and functional materials. Rational engineering of self-assembling systems requires understanding of the accessible aggregation states and the structural assembly pathways. In this work, we apply nonlinear machine learning to experimental particle tracking data to infer low-dimensional assembly landscapes mapping the morphology, stability, and assembly pathways of accessible aggregates as a function of experimental conditions. To the best of our knowledge, this represents the first time that collective order parameters and assembly landscapes have been inferred directly from experimental data. We apply this technique to the nonequilibrium self-assembly of metallodielectric Janus colloids in an oscillating electric field, and quantify the impact of field strength, oscillation frequency, and salt concentration on the dominant assembly pathways and terminal aggregates. This combined computational and experimental framework furnishes new understanding of self-assembling systems, and quantitatively informs rational engineering of experimental conditions to drive assembly along desired aggregation pathways.

Characterization of a Track-and-Hold Amplifier for Application to a High Performance SAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

DUBBERT, DALE F.; HARDIN, TERRY LYNN; DELAPLAIN, GILBERT G.

2002-07-01

A Synthetic Aperture Radar (SAR) which employs direct IF sampling can significantly reduce the complexity of the analog electronics prior to the analog-to-digital converter (ADC). For relatively high frequency IF bands, a wide-bandwidth track-and-hold amplifier (THA) is required prior to the ADC. The THA functions primarily as a means of converting, through bandpass sampling, the IF signal to a baseband signal which can be sampled by the ADC. For a wide-band, high dynamic-range receiver system, such as a SAR receiver, stringent performance requirements are placed on the THA. We first measure the THA parameters such as gain, gain compression, third-ordermore » intercept (TOI), signal-to-noise ratio (SNR), spurious-free dynamic-range (SFDR), noise figure (NF), and phase noise. The results are then analyzed in terms of their respective impact on the overall performance of the SAR. The specific THA under consideration is the Rockwell Scientific RTH010.« less

Liquid filtration properties in gravel foundation of railroad tracks

NASA Astrophysics Data System (ADS)

Strelkov, A.; Teplykh, S.; Bukhman, N.

2016-08-01

Railway bed gravel foundation has a constant permanent impact on urban ecology and ground surface. It is only natural that larger objects, such as railway stations, make broader impact. Surface run-off waters polluted by harmful substances existing in railroad track body (ballast section) flow along railroad tracks and within macadam, go down into subterranean ground flow and then enter neighbouring rivers and water basins. This paper presents analytic calculations and characteristics of surface run-off liquid filtration which flows through gravel multiple layers (railroad track ballast section). The authors analyse liquids with various density and viscosity flowing in multi-layer porous medium. The paper also describes liquid stationary and non-stationary weepage into gravel foundation of railroad tracks.

Study of performance of the ATLAS transition radiation tracker in run 1 of the LHC: Tracking characteristics

NASA Astrophysics Data System (ADS)

Belyaev, N.; Krasnopevtsev, D.; Smirnov, N.

2018-01-01

The ATLAS Transition Radiation Tracker (TRT) contains more than 350000 large straw tubes and it is the outermost of the three subsystems of the ATLAS Inner Detector (ID). The TRT contributes substantially to the ATLAS ID resolution for the tracks of high-energy particles, providing excellent particle identification capabilities and electron-pion separation. Basic performance parameters of the TRT related to its tracking function are described in this paper. The data used in this study were collected during the first period of the Large Hadron Collider (LHC) operation in 2012 with a proton collision energy of 8 TeV. The tracking performance of the TRT has been studied in the case of operating with a Xe-based gas mixture and as a function of the straw occupancy. Special attention was paid to investigation of tracking parameters inside hadronic jets. The experimental data and simulation are in reasonable agreement, even within the dense cores of the most energetic jets.

C-band radar calibration using GEOS-3

NASA Technical Reports Server (NTRS)

Krabill, W. B.; Martin, C. F.

1978-01-01

The various methods of determining tracking radar measurement error parameters are described, along with the projected accuracy of results. Typical examples and results for calibration of radars tracking the GEOS-3 satellite are presented.

A pilot study of eye-tracking devices in intensive care.

PubMed

Garry, Jonah; Casey, Kelly; Cole, Therese Kling; Regensburg, Angela; McElroy, Colleen; Schneider, Eric; Efron, David; Chi, Albert

2016-03-01

Eye-tracking devices have been suggested as a means of improving communication and psychosocial status among patients in the intensive care unit (ICU). This study was undertaken to explore the psychosocial impact and communication effects of eye-tracking devices in the ICU. A convenience sample of patients in the medical ICU, surgical ICU, and neurosciences critical care unit were enrolled prospectively. Patients participated in 5 guided sessions of 45 minutes each with the eye-tracking computer. After completion of the sessions, the Psychosocial Impact of Assistive Devices Scale (PIADS) was used to evaluate the device from the patient's perspective. All patients who participated in the study were able to communicate basic needs to nursing staff and family. Delirium as assessed by the Confusion Assessment Method for the Intensive Care Unit was present in 4 patients at recruitment and none after training. The device's overall psychosocial impact ranged from neutral (-0.29) to strongly positive (2.76). Compared with the absence of intervention (0 = no change), patients exposed to eye-tracking computers demonstrated a positive mean overall impact score (PIADS = 1.30; P = .004). This finding was present in mean scores for each PIADS domain: competence = 1.26, adaptability = 1.60, and self-esteem = 1.02 (all P < .01). There is a population of patients in the ICU whose psychosocial status, delirium, and communication ability may be enhanced by eye-tracking devices. These 3 outcomes are intertwined with ICU patient outcomes and indirectly suggest that eye-tracking devices might improve outcomes. A more in-depth exploration of the population to be targeted, the device's limitations, and the benefits of eye-tracking devices in the ICU is warranted. Copyright © 2016 Elsevier Inc. All rights reserved.

Infrared Spectroscopy of Wild 2 Particle Hypervelocity Tracks in Stardust Aerogel: Evidence for the presence of Volatile Organics in Comet Dust

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bajt, S; Sandford, S A; Flynn, G J

2007-08-28

Infrared spectroscopy maps of some tracks, made by cometary dust from 81P/Wild 2 impacting Stardust aerogel, reveal an interesting distribution of volatile organic material. Out of six examined tracks three show presence of volatile organic components possibly injected into the aerogel during particle impacts. When particle tracks contained excess volatile organic material, they were found to be -CH{sub 2}-rich. Off-normal particle tracks could indicate impacts by lower velocity particles that could have bounced off the Whipple shield, therefore carry off some contamination from it. However, this theory is not supported by data that show excess organic-rich material in normal andmore » off-normal particle tracks. It is clear that the population of cometary particles impacting the Stardust aerogel collectors also include grains that contained little or none of this volatile organic component. This observation is consistent with the highly heterogeneous nature of the collected grains, as seen by a multitude of other analytical techniques. We propose that at least some of the volatile organic material might be of cometary origin based on supporting data shown in this paper. However, we also acknowledge the presence of carbon (primarily as -CH{sub 3}) in the original aerogel, which complicates interpretation of these results.« less

Influence of some vehicle and track parameters on the environmental vibrations induced by railway traffic

NASA Astrophysics Data System (ADS)

Kouroussis, G.; Verlinden, O.; Conti, C.

2012-04-01

A study is performed on the influence of some typical railway vehicle and track parameters on the level of ground vibrations induced in the neighbourhood. The results are obtained from a previously validated simulation framework considering in a first step the vehicle/track subsystem and, in a second step, the response of the soil to the forces resulting from the first analysis. The vehicle is reduced to a simple vertical 3-dof model, corresponding to the superposition of the wheelset, the bogie and the car body. The rail is modelled as a succession of beam elements elastically supported by the sleepers, lying themselves on a flexible foundation representing the ballast and the subgrade. The connection between the wheels and the rails is realised through a non-linear Hertzian contact. The soil motion is obtained from a finite/infinite element model. The investigated vehicle parameters are its type (urban, high speed, freight, etc.) and its speed. For the track, the rail flexural stiffness, the railpad stiffness, the spacing between sleepers and the rail and sleeper masses are considered. In all cases, the parameter value range is defined from a bibliographic browsing. At the end, the paper proposes a table summarising the influence of each studied parameter on three indicators: the vehicle acceleration, the rail velocity and the soil velocity. It namely turns out that the vehicle has a serious influence on the vibration level and should be considered in prediction models.

Impacts of tourism hotspots on vegetation communities show a higher potential for self-propagation along roads than hiking trails.

PubMed

Wolf, Isabelle D; Croft, David B

2014-10-01

Vegetation communities along recreational tracks may suffer from substantial edge-effects through the impacts of trampling, modified environmental conditions and competition with species that benefit from disturbance. We assessed impacts on trackside vegetation by comparing high and low usage tourism sites at a 1-10 m distance from recreational tracks in a popular arid-lands tourism destination in South Australia. The central aim was quantification of the strengths and spatial extent of tourism impacts along recreational tracks with a qualitative comparison of roads and trails. Track-distance gradients were most prevalent at high usage sites. There, species community composition was altered, total plant cover decreased, non-native species cover increased, plant diversity increased or decreased (depending on the distance) and soil compaction increased towards recreational tracks. Roadside effects were greater and more pervasive than trailside effects. Further, plant diversity did not continuously increase towards the road verge as it did along trails but dropped sharply in the immediate road shoulder which indicated high disturbance conditions that few species were able to tolerate. To our knowledge, we are the first to demonstrate that the access mode to a recreation site influences the potential of certain impacts, such as the increase of non-native species, to self-perpetuate from their points of introduction to disjointed sites with a predisposition to disturbance. Due to this propulsion of impacts, the overall spatial extent of roadside impacts was far greater than initially apparent from assessments at the road verge. We discuss possible means of mitigating these impacts. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dielectric elastomer for stretchable sensors: influence of the design and material properties

NASA Astrophysics Data System (ADS)

Jean-Mistral, C.; Iglesias, S.; Pruvost, S.; Duchet-Rumeau, J.; Chesné, S.

2016-04-01

Dielectric elastomers exhibit extended capabilities as flexible sensors for the detection of load distributions, pressure or huge deformations. Tracking the human movements of the fingers or the arms could be useful for the reconstruction of sporting gesture, or to control a human-like robot. Proposing new measurements methods are addressed in a number of publications leading to improving the sensitivity and accuracy of the sensing method. Generally, the associated modelling remains simple (RC or RC transmission line). The material parameters are considered constant or having a negligible effect which can lead to serious reduction of accuracy. Comparisons between measurements and modelling require care and skill, and could be tricky. Thus, we propose here a comprehensive modelling, taking into account the influence of the material properties on the performances of the dielectric elastomer sensor (DES). Various parameters influencing the characteristics of the sensors have been identified: dielectric constant, hyper-elasticity. The variations of these parameters as a function of the strain impact the linearity and sensitivity of the sensor of few percent. The sensitivity of the DES is also evaluated changing geometrical parameters (initial thickness) and its design (rectangular and dog-bone shapes). We discuss the impact of the shape regarding stress. Finally, DES including a silicone elastomer sandwiched between two high conductive stretchable electrodes, were manufactured and investigated. Classic and reliable LCR measurements are detailed. Experimental results validate our numerical model of large strain sensor (>50%).

Synthesis of Algorithm for Range Measurement Equipment to Track Maneuvering Aircraft Using Data on Its Dynamic and Kinematic Parameters

NASA Astrophysics Data System (ADS)

Pudovkin, A. P.; Panasyuk, Yu N.; Danilov, S. N.; Moskvitin, S. P.

2018-05-01

The problem of improving automated air traffic control systems is considered through the example of the operation algorithm synthesis for a range measurement channel to track the aircraft, using its kinematic and dynamic parameters. The choice of the state and observation models has been justified, the computer simulations have been performed and the results of the investigated algorithms have been obtained.

Recovery of refractivity profiles and pressure and temperature distributions in the lower atmosphere from satellite-to-satellite radio occultation data

NASA Technical Reports Server (NTRS)

Murray, C. W., Jr.

1977-01-01

The feasibility of recovering parameters from one-way range rate between two earth orbiting spacecraft during occultation of the tracking signal by the earth's lower atmosphere. The tracking data is inverted by an integral transformation (Abel transform) to obtain a vertical refractivity profile above the point of closest approach of the ray connecting the satellites. Pressure and temperature distributions can be obtained from values of dry refractivity using the hydrostatic equation and perfect gas law. Two methods are investigated for recovering pressure and temperature parameters. Results show that recovery is much more sensitive to satellite velocity errors than to satellite position errors. An error analysis is performed. An example is given demonstrating recovery of parameters from radio occultation data obtained during satellite-to-satellite tracking of Nimbus 6 by the ATS 6 satellite.

Integration of an On-Axis General Sun-Tracking Formula in the Algorithm of an Open-Loop Sun-Tracking System

PubMed Central

Chong, Kok-Keong; Wong, Chee-Woon; Siaw, Fei-Lu; Yew, Tiong-Keat; Ng, See-Seng; Liang, Meng-Suan; Lim, Yun-Seng; Lau, Sing-Liong

2009-01-01

A novel on-axis general sun-tracking formula has been integrated in the algorithm of an open-loop sun-tracking system in order to track the sun accurately and cost effectively. Sun-tracking errors due to installation defects of the 25 m2 prototype solar concentrator have been analyzed from recorded solar images with the use of a CCD camera. With the recorded data, misaligned angles from ideal azimuth-elevation axes have been determined and corrected by a straightforward changing of the parameters' values in the general formula of the tracking algorithm to improve the tracking accuracy to 2.99 mrad, which falls below the encoder resolution limit of 4.13 mrad. PMID:22408483

Off-line tracking of series parameters in distribution systems using AMI data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Tess L.; Sun, Yannan; Schneider, Kevin

2016-05-01

Electric distribution systems have historically lacked measurement points, and equipment is often operated to its failure point, resulting in customer outages. The widespread deployment of sensors at the distribution level is enabling observability. This paper presents an off-line parameter value tracking procedure that takes advantage of the increasing number of measurement devices being deployed at the distribution level to estimate changes in series impedance parameter values over time. The tracking of parameter values enables non-diurnal and non-seasonal change to be flagged for investigation. The presented method uses an unbalanced Distribution System State Estimation (DSSE) and a measurement residual-based parameter estimationmore » procedure. Measurement residuals from multiple measurement snapshots are combined in order to increase the effective local redundancy and improve the robustness of the calculations in the presence of measurement noise. Data from devices on the primary distribution system and from customer meters, via an AMI system, form the input data set. Results of simulations on the IEEE 13-Node Test Feeder are presented to illustrate the proposed approach applied to changes in series impedance parameters. A 5% change in series resistance elements can be detected in the presence of 2% measurement error when combining less than 1 day of measurement snapshots into a single estimate.« less

Elevated intracranial pressure and reversible eye-tracking changes detected while viewing a film clip.

PubMed

Kolecki, Radek; Dammavalam, Vikalpa; Bin Zahid, Abdullah; Hubbard, Molly; Choudhry, Osamah; Reyes, Marleen; Han, ByoungJun; Wang, Tom; Papas, Paraskevi Vivian; Adem, Aylin; North, Emily; Gilbertson, David T; Kondziolka, Douglas; Huang, Jason H; Huang, Paul P; Samadani, Uzma

2018-03-01

OBJECTIVE The precise threshold differentiating normal and elevated intracranial pressure (ICP) is variable among individuals. In the context of several pathophysiological conditions, elevated ICP leads to abnormalities in global cerebral functioning and impacts the function of cranial nerves (CNs), either or both of which may contribute to ocular dysmotility. The purpose of this study was to assess the impact of elevated ICP on eye-tracking performed while patients were watching a short film clip. METHODS Awake patients requiring placement of an ICP monitor for clinical purposes underwent eye tracking while watching a 220-second continuously playing video moving around the perimeter of a viewing monitor. Pupil position was recorded at 500 Hz and metrics associated with each eye individually and both eyes together were calculated. Linear regression with generalized estimating equations was performed to test the association of eye-tracking metrics with changes in ICP. RESULTS Eye tracking was performed at ICP levels ranging from -3 to 30 mm Hg in 23 patients (12 women, 11 men, mean age 46.8 years) on 55 separate occasions. Eye-tracking measures correlating with CN function linearly decreased with increasing ICP (p < 0.001). Measures for CN VI were most prominently affected. The area under the curve (AUC) for eye-tracking metrics to discriminate between ICP < 12 and ≥ 12 mm Hg was 0.798. To discriminate an ICP < 15 from ≥ 15 mm Hg the AUC was 0.833, and to discriminate ICP < 20 from ≥ 20 mm Hg the AUC was 0.889. CONCLUSIONS Increasingly elevated ICP was associated with increasingly abnormal eye tracking detected while patients were watching a short film clip. These results suggest that eye tracking may be used as a noninvasive, automatable means to quantitate the physiological impact of elevated ICP, which has clinical application for assessment of shunt malfunction, pseudotumor cerebri, concussion, and prevention of second-impact syndrome.

Occultation of 2UCAC 42376428 by (423) Diotima on 2005 March 06

NASA Astrophysics Data System (ADS)

Vasundhara, R.; Kuppuswamy, K.; Ramamoorthy, S.; Velu, C.; Venkataramana, A. K.

2006-03-01

Observations of the occultation of the star 2UCAC 42376428 by (423) Diotima on 2005 March 06 at the Vainu Bappu Observatory are reported. The observed mid time of the event at 15:12:25.1 UT occurred 3.4 s later than the predicted time but within the 1 uncertainty of 4.3 s of the predictions by IOTA. The duration of the event of 4.2 s was found to be shorter than the predictions even allowing for a one sigma uncertainty in the impact parameter. This implies a narrower projected width of the asteroid along the occultation track at the time of the event.

LightForce: An Update on Orbital Collision Avoidance Using Photon Pressure

NASA Technical Reports Server (NTRS)

Stupl, Jan; Mason, James; De Vries, Willem; Smith, Craig; Levit, Creon; Marshall, William; Salas, Alberto Guillen; Pertica, Alexander; Olivier, Scot; Ting, Wang

2012-01-01

We present an update on our research on collision avoidance using photon-pressure induced by ground-based lasers. In the past, we have shown the general feasibility of employing small orbit perturbations, induced by photon pressure from ground-based laser illumination, for collision avoidance in space. Possible applications would be protecting space assets from impacts with debris and stabilizing the orbital debris environment. Focusing on collision avoidance rather than de-orbit, the scheme avoids some of the security and liability implications of active debris removal, and requires less sophisticated hardware than laser ablation. In earlier research we concluded that one ground based system consisting of a 10 kW class laser, directed by a 1.5 m telescope with adaptive optics, could avoid a significant fraction of debris-debris collisions in low Earth orbit. This paper describes our recent efforts, which include refining our original analysis, employing higher fidelity simulations and performing experimental tracking tests. We investigate the efficacy of one or more laser ground stations for debris-debris collision avoidance and satellite protection using simulations to investigate multiple case studies. The approach includes modeling of laser beam propagation through the atmosphere, the debris environment (including actual trajectories and physical parameters), laser facility operations, and simulations of the resulting photon pressure. We also present the results of experimental laser debris tracking tests. These tests track potential targets of a first technical demonstration and quantify the achievable tracking performance.

Regional Differences in Stratospheric Intrusions over the USA Investigated using the NASA MERRA-2 Reanalysis

NASA Astrophysics Data System (ADS)

Knowland, K. E.; Ott, L.; Hodges, K.; Wargan, K.; Duncan, B. N.

2016-12-01

Stratospheric intrusions (SI) - the introduction of ozone-rich stratospheric air into the troposphere - have been linked with surface ozone air quality exceedences, especially at the high elevations in the western USA in springtime. However, the impact of SIs in the remaining seasons and over the rest of the USA is less clear. This study investigates the atmospheric dynamics that generate SIs over the western USA and the different mechanisms through which SIs may influence atmospheric chemistry and surface air quality over the eastern USA. An analysis of the spatiotemporal variability of SIs over the continental US is performed using NASA's Modern-Era Retrospective Analysis for Research and Applications Version-2 (MERRA-2) reanalysis dataset and other Goddard Earth Observing System Model, Version 5 (GEOS-5) model products. Both upper-level and lower-level dynamical features are examined on seasonal timescales using the tracking algorithm of Hodges (1995, 1999). We show how upper-level relative vorticity maxima - representing troughs and cut-off lows - can be tracked and related to the lower-level storm tracks. The influence of both sets of tracks on the assimilated MERRA-2 ozone and meteorological parameters throughout the troposphere and lower stratosphere is quantified. By focusing on the major modes of variability that influence the weather patterns in the USA, namely the Pacific North American (PNA) pattern, Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO), predicative patterns in the meteorological fields that are associated with SIs are identified for their regional effects.

The Development of Tracking and Its Historical Impact on Minority Students

ERIC Educational Resources Information Center

Culpepper, Deberae

2012-01-01

In the 1920s, high school students were placed on one of three tracks: high, average, and low. Over the years, vocational education was transformed into a low track assignment for students, often racial minorities, who were perceived as less intelligent. However, the interaction between vocational education and tracking policies and practices…

Non-iterative double-frame 2D/3D particle tracking velocimetry

NASA Astrophysics Data System (ADS)

Fuchs, Thomas; Hain, Rainer; Kähler, Christian J.

2017-09-01

In recent years, the detection of individual particle images and their tracking over time to determine the local flow velocity has become quite popular for planar and volumetric measurements. Particle tracking velocimetry has strong advantages compared to the statistical analysis of an ensemble of particle images by means of cross-correlation approaches, such as particle image velocimetry. Tracking individual particles does not suffer from spatial averaging and therefore bias errors can be avoided. Furthermore, the spatial resolution can be increased up to the sub-pixel level for mean fields. A maximization of the spatial resolution for instantaneous measurements requires high seeding concentrations. However, it is still challenging to track particles at high seeding concentrations, if no time series is available. Tracking methods used under these conditions are typically very complex iterative algorithms, which require expert knowledge due to the large number of adjustable parameters. To overcome these drawbacks, a new non-iterative tracking approach is introduced in this letter, which automatically analyzes the motion of the neighboring particles without requiring to specify any parameters, except for the displacement limits. This makes the algorithm very user friendly and also offers unexperienced users to use and implement particle tracking. In addition, the algorithm enables measurements of high speed flows using standard double-pulse equipment and estimates the flow velocity reliably even at large particle image densities.

TRIAC II. A MatLab code for track measurements from SSNT detectors

NASA Astrophysics Data System (ADS)

Patiris, D. L.; Blekas, K.; Ioannides, K. G.

2007-08-01

A computer program named TRIAC II written in MATLAB and running with a friendly GUI has been developed for recognition and parameters measurements of particles' tracks from images of Solid State Nuclear Track Detectors. The program, using image analysis tools, counts the number of tracks and depending on the current working mode classifies them according to their radii (Mode I—circular tracks) or their axis (Mode II—elliptical tracks), their mean intensity value (brightness) and their orientation. Images of the detectors' surfaces are input to the code, which generates text files as output, including the number of counted tracks with the associated track parameters. Hough transform techniques are used for the estimation of the number of tracks and their parameters, providing results even in cases of overlapping tracks. Finally, it is possible for the user to obtain informative histograms as well as output files for each image and/or group of images. Program summaryTitle of program:TRIAC II Catalogue identifier:ADZC_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZC_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer: Pentium III, 600 MHz Installations: MATLAB 7.0 Operating system under which the program has been tested: Windows XP Programming language used:MATLAB Memory required to execute with typical data:256 MB No. of bits in a word:32 No. of processors used:one Has the code been vectorized or parallelized?:no No. of lines in distributed program, including test data, etc.:25 964 No. of bytes in distributed program including test data, etc.: 4 354 510 Distribution format:tar.gz Additional comments: This program requires the MatLab Statistical toolbox and the Image Processing Toolbox to be installed. Nature of physical problem: Following the passage of a charged particle (protons and heavier) through a Solid State Nuclear Track Detector (SSNTD), a damage region is created, usually named latent track. After the chemical etching of the detectors in aqueous NaOH or KOH solutions, latent tracks can be sufficiently enlarged (with diameters of 1 μm or more) to become visible under an optical microscope. Using the appropriate apparatus, one can record images of the SSNTD's surface. The shapes of the particle's tracks are strongly dependent on their charge, energy and the angle of incidence. Generally, they have elliptical shapes and in the special case of vertical incidence, they are circular. The manual counting of tracks is a tedious and time-consuming task. An automatic system is needed to speed up the process and to increase the accuracy of the results. Method of solution: TRIAC II is based on a segmentation method that groups image pixels according to their intensity value (brightness) in a number of grey level groups. After the segmentation of pixels, the program recognizes and separates the track from the background, subsequently performing image morphology, where oversized objects or objects smaller than a threshold value are removed. Finally, using the appropriate Hough transform technique, the program counts the tracks, even those which overlap and classifies them according to their shape parameters and brightness. Typical running time: The analysis of an image with a PC (Intel Pentium III processor running at 600 MHz) requires 2 to 10 minutes, depending on the number of observed tracks and the digital resolution of the image. Unusual features of the program: This program has been tested with images of CR-39 detectors exposed to alpha particles. Also, in low contrast images with few or small tracks, background pixels can be recognized as track pixels. To avoid this problem the brightness of the background pixels should be sufficiently higher than that of the track pixels.

Stardust Interstellar Preliminary Examination V: XRF Analyses of Interstellar Dust Candidates at ESRF ID13

NASA Technical Reports Server (NTRS)

Brenker, Frank E.; Westphal, Andrew J.; Simionovici, Alexandre S.; Flynn, George J.; Gainsforth, Zack; Allen, Carlton C.; Sanford, Scott; Zolensky, Michael E.; Bastien, Ron K.; Frank, David R.

2014-01-01

Here, we report analyses by synchrotron X-ray fluorescence microscopy of the elemental composition of eight candidate impact features extracted from the Stardust Interstellar Dust Collector (SIDC). Six of the features were unambiguous tracks, and two were crater-like features. Five of the tracks are so-called midnight tracks that is, they had trajectories consistent with an origin either in the interstellar dust stream or as secondaries from impacts on the Sample Return Capsule (SRC). In a companion paper reporting synchrotron X-ray diffraction analyses of ISPE candidates, we show that two of these particles contain natural crystalline materials: the terminal particle of track 30contains olivine and spinel, and the terminal particle of track 34 contains olivine. Here, we show that the terminal particle of track 30, Orion, shows elemental abundances, normalized to Fe, that are close to CI values, and a complex, fine-grained structure. The terminal particle of track 34, Hylabrook, shows abundances that deviate strongly from CI, but shows little fine structure and is nearly homogenous. The terminal particles of other midnight tracks, 29 and 37, had heavy element abundances below detection threshold. A third, track28, showed a composition inconsistent with an extraterrestrial origin, but also inconsistent with known spacecraft materials. A sixth track, with a trajectory consistent with secondary ejecta from an impact on one of the spacecraft solar panels, contains abundant Ce and Zn. This is consistent with the known composition of the glass covering the solar panel. Neither crater-like feature is likely to be associated with extraterrestrial materials. We also analyzed blank aerogel samples to characterize background and variability between aerogel tiles. We found significant differences in contamination levels and compositions, emphasizing the need for local background subtraction for accurate quantification.

A novel approach to Hough Transform for implementation in fast triggers

NASA Astrophysics Data System (ADS)

Pozzobon, Nicola; Montecassiano, Fabio; Zotto, Pierluigi

2016-10-01

Telescopes of position sensitive detectors are common layouts in charged particles tracking, and programmable logic devices, such as FPGAs, represent a viable choice for the real-time reconstruction of track segments in such detector arrays. A compact implementation of the Hough Transform for fast triggers in High Energy Physics, exploiting a parameter reduction method, is proposed, targeting the reduction of the needed storage or computing resources in current, or next future, state-of-the-art FPGA devices, while retaining high resolution over a wide range of track parameters. The proposed approach is compared to a Standard Hough Transform with particular emphasis on their application to muon detectors. In both cases, an original readout implementation is modeled.

The seam visual tracking method for large structures

NASA Astrophysics Data System (ADS)

Bi, Qilin; Jiang, Xiaomin; Liu, Xiaoguang; Cheng, Taobo; Zhu, Yulong

2017-10-01

In this paper, a compact and flexible weld visual tracking method is proposed. Firstly, there was the interference between the visual device and the work-piece to be welded when visual tracking height cannot change. a kind of weld vision system with compact structure and tracking height is researched. Secondly, according to analyze the relative spatial pose between the camera, the laser and the work-piece to be welded and study with the theory of relative geometric imaging, The mathematical model between image feature parameters and three-dimensional trajectory of the assembly gap to be welded is established. Thirdly, the visual imaging parameters of line structured light are optimized by experiment of the weld structure of the weld. Fourth, the interference that line structure light will be scatters at the bright area of metal and the area of surface scratches will be bright is exited in the imaging. These disturbances seriously affect the computational efficiency. The algorithm based on the human eye visual attention mechanism is used to extract the weld characteristics efficiently and stably. Finally, in the experiment, It is verified that the compact and flexible weld tracking method has the tracking accuracy of 0.5mm in the tracking of large structural parts. It is a wide range of industrial application prospects.

Potential benefits of dosimetric VMAT tracking verified with 3D film measurements.

PubMed

Crijns, Wouter; Defraene, Gilles; Van Herck, Hans; Depuydt, Tom; Haustermans, Karin; Maes, Frederik; Van den Heuvel, Frank

2016-05-01

To evaluate three different plan adaptation strategies using 3D film-stack dose measurements of both focal boost and hypofractionated prostate VMAT treatments. The adaptation strategies (a couch shift, geometric tracking, and dosimetric tracking) were applied for three realistic intrafraction prostate motions. A focal boost (35 × 2.2 and 35 × 2.7 Gy) and a hypofractionated (5 × 7.25 Gy) prostate VMAT plan were created for a heterogeneous phantom that allows for internal prostate motion. For these plans geometric tracking and dosimetric tracking were evaluated by ionization chamber (IC) point dose measurements (zero-D) and measurements using a stack of EBT3 films (3D). The geometric tracking applied translations, rotations, and scaling of the MLC aperture in response to realistic prostate motions. The dosimetric tracking additionally corrected the monitor units to resolve variations due to difference in depth, tissue heterogeneity, and MLC-aperture. The tracking was based on the positions of four fiducial points only. The film measurements were compared to the gold standard (i.e., IC measurements) and the planned dose distribution. Additionally, the 3D measurements were converted to dose volume histograms, tumor control probability, and normal tissue complication probability parameters (DVH/TCP/NTCP) as a direct estimate of clinical relevance of the proposed tracking. Compared to the planned dose distribution, measurements without prostate motion and tracking showed already a reduced homogeneity of the dose distribution. Adding prostate motion further blurs the DVHs for all treatment approaches. The clinical practice (no tracking) delivered the dose distribution inside the PTV but off target (CTV), resulting in boost dose errors up to 10%. The geometric and dosimetric tracking corrected the dose distribution's position. Moreover, the dosimetric tracking could achieve the planned boost DVH, but not the DVH of the more homogeneously irradiated prostate. A drawback of both the geometric and dosimetric tracking was a reduced MLC blocking caused by the rotational component of the MLC aperture corrections. Because of the used CTV to PTV margins and the high doses in the considered fractionation schemes, the TCP differed less than 0.02 from the planned value for all targets and all correction methods. The rectal NTCP constraints, however, could not be realized using any of these methods. The geometric and dosimetric tracking use only a limited input, but they deposit the dose distribution with higher geometric accuracy than the clinical practice. The latter case has boost dose errors up to 10%. The increased accuracy has a modest impact [Δ(NT)CP < 0.02] because of the applied margins and the high dose levels used. To allow further margin reduction tracking methods are vital. The proposed methodology could further be improved by implementing a rotational correction using collimator rotations.

Estimation of effective connectivity via data-driven neural modeling

PubMed Central

Freestone, Dean R.; Karoly, Philippa J.; Nešić, Dragan; Aram, Parham; Cook, Mark J.; Grayden, David B.

2014-01-01

This research introduces a new method for functional brain imaging via a process of model inversion. By estimating parameters of a computational model, we are able to track effective connectivity and mean membrane potential dynamics that cannot be directly measured using electrophysiological measurements alone. The ability to track the hidden aspects of neurophysiology will have a profound impact on the way we understand and treat epilepsy. For example, under the assumption the model captures the key features of the cortical circuits of interest, the framework will provide insights into seizure initiation and termination on a patient-specific basis. It will enable investigation into the effect a particular drug has on specific neural populations and connectivity structures using minimally invasive measurements. The method is based on approximating brain networks using an interconnected neural population model. The neural population model is based on a neural mass model that describes the functional activity of the brain, capturing the mesoscopic biophysics and anatomical structure. The model is made subject-specific by estimating the strength of intra-cortical connections within a region and inter-cortical connections between regions using a novel Kalman filtering method. We demonstrate through simulation how the framework can be used to track the mechanisms involved in seizure initiation and termination. PMID:25506315

Information Technology: Making It All Fit. Track III: Financial Impact and Considerations.

ERIC Educational Resources Information Center

CAUSE, Boulder, CO.

Seven papers from the 1988 CAUSE conference's Track III, Financial Impact and Considerations, are presented. They include: "Providing Applications Development Services in a Competitive Environment" (Donald E. Heller and Mary Ellen Bushnell); "The Cost of Not Staying Current" (Jack T. Tinsley and Betty R. Nyer); "Project…

Thermodynamics of nuclear track chemical etching

NASA Astrophysics Data System (ADS)

Rana, Mukhtar Ahmed

2018-05-01

This is a brief paper with new and useful scientific information on nuclear track chemical etching. Nuclear track etching is described here by using basic concepts of thermodynamics. Enthalpy, entropy and free energy parameters are considered for the nuclear track etching. The free energy of etching is determined using etching experiments of fission fragment tracks in CR-39. Relationship between the free energy and the etching temperature is explored and is found to be approximately linear. The above relationship is discussed. A simple enthalpy-entropy model of chemical etching is presented. Experimental and computational results presented here are of fundamental interest in nuclear track detection methodology.

Image processing analysis of nuclear track parameters for CR-39 detector irradiated by thermal neutron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Jobouri, Hussain A., E-mail: hahmed54@gmail.com; Rajab, Mustafa Y., E-mail: mostafaheete@gmail.com

CR-39 detector which covered with boric acid (H{sub 3}Bo{sub 3}) pellet was irradiated by thermal neutrons from ({sup 241}Am - {sup 9}Be) source with activity 12Ci and neutron flux 10{sup 5} n. cm{sup −2}. s{sup −1}. The irradiation times -T{sub D} for detector were 4h, 8h, 16h and 24h. Chemical etching solution for detector was sodium hydroxide NaOH, 6.25N with 45 min etching time and 60 C° temperature. Images of CR-39 detector after chemical etching were taken from digital camera which connected from optical microscope. MATLAB software version 7.0 was used to image processing. The outputs of image processing of MATLABmore » software were analyzed and found the following relationships: (a) The irradiation time -T{sub D} has behavior linear relationships with following nuclear track parameters: i) total track number - N{sub T} ii) maximum track number - MRD (relative to track diameter - D{sub T}) at response region range 2.5 µm to 4 µm iii) maximum track number - M{sub D} (without depending on track diameter - D{sub T}). (b) The irradiation time -T{sub D} has behavior logarithmic relationship with maximum track number - M{sub A} (without depending on track area - A{sub T}). The image processing technique principally track diameter - D{sub T} can be take into account to classification of α-particle emitters, In addition to the contribution of these technique in preparation of nano- filters and nano-membrane in nanotechnology fields.« less

Method and apparatus for optimizing a train trip using signal information

DOEpatents

Kumar, Ajith Kuttannair; Daum, Wolfgang; Otsubo, Tom; Hershey, John Erik; Hess, Gerald James

2014-06-10

A system is provided for operating a railway network including a first railway vehicle during a trip along track segments. The system includes a first element for determining travel parameters of the first railway vehicle, a second element for determining travel parameters of a second railway vehicle relative to the track segments to be traversed by the first vehicle during the trip, a processor for receiving information from the first and the second elements and for determining a relationship between occupation of a track segment by the second vehicle and later occupation of the same track segment by the first vehicle and an algorithm embodied within the processor having access to the information to create a trip plan that determines a speed trajectory for the first vehicle. The speed trajectory is responsive to the relationship and further in accordance with one or more operational criteria for the first vehicle.

Intelligent Tracking Control for a Class of Uncertain High-Order Nonlinear Systems.

PubMed

Zhao, Xudong; Shi, Peng; Zheng, Xiaolong; Zhang, Jianhua

2016-09-01

This brief is concerned with the problem of intelligent tracking control for a class of high-order nonlinear systems with completely unknown nonlinearities. An intelligent adaptive control algorithm is presented by combining the adaptive backstepping technique with the neural networks' approximation ability. It is shown that the practical output tracking performance of the system is achieved using the proposed state-feedback controller under two mild assumptions. In particular, by introducing a parameter in the derivations, the tracking error between the time-varying target signal and the output can be reduced via tuning the controller design parameters. Moreover, in order to solve the problem of overparameterization, which is a common issue in adaptive control design, a controller with one adaptive law is also designed. Finally, simulation results are given to show the effectiveness of the theoretical approaches and the potential of the proposed new design techniques.

The effect of racetrack design on gait symmetry of the pacer.

PubMed Central

Crawford, W H; Leach, D H

1984-01-01

A survey of a western Canadian racetrack determined the superelevation and transition curves to be less than the cited design standards. High-speed cinematography was used to film seven Standardbred pacers as they proceeded around one curve of the track at racing speed and for each horse 19 temporal stride parameters were obtained from these films using a film analyzer system. Average velocities were calculated and the mean stride length was found to vary from 5.08 m to 5.77 m. In all frames analyzed the hind foot was observed to contact the track surface prior to the ipsilateral forefoot and all horses displayed significant (p less than 0.05) contralateral asymmetry of some temporal stride parameters. Fifteen temporal stride parameters were significantly different (p less than 0.05) when compared between horses but only three temporal stride parameters were significantly different (p less than 0.05) when their values were compared between segments of the curved portions of the track. It is suggested that temporal gait asymmetry should not be used to judge the standards of racetrack design. PMID:6509365

The effect of racetrack design on gait symmetry of the pacer.

PubMed

Crawford, W H; Leach, D H

1984-10-01

A survey of a western Canadian racetrack determined the superelevation and transition curves to be less than the cited design standards. High-speed cinematography was used to film seven Standardbred pacers as they proceeded around one curve of the track at racing speed and for each horse 19 temporal stride parameters were obtained from these films using a film analyzer system. Average velocities were calculated and the mean stride length was found to vary from 5.08 m to 5.77 m. In all frames analyzed the hind foot was observed to contact the track surface prior to the ipsilateral forefoot and all horses displayed significant (p less than 0.05) contralateral asymmetry of some temporal stride parameters. Fifteen temporal stride parameters were significantly different (p less than 0.05) when compared between horses but only three temporal stride parameters were significantly different (p less than 0.05) when their values were compared between segments of the curved portions of the track. It is suggested that temporal gait asymmetry should not be used to judge the standards of racetrack design.

Research on polarization imaging information parsing method

NASA Astrophysics Data System (ADS)

Yuan, Hongwu; Zhou, Pucheng; Wang, Xiaolong

2016-11-01

Polarization information parsing plays an important role in polarization imaging detection. This paper focus on the polarization information parsing method: Firstly, the general process of polarization information parsing is given, mainly including polarization image preprocessing, multiple polarization parameters calculation, polarization image fusion and polarization image tracking, etc.; And then the research achievements of the polarization information parsing method are presented, in terms of polarization image preprocessing, the polarization image registration method based on the maximum mutual information is designed. The experiment shows that this method can improve the precision of registration and be satisfied the need of polarization information parsing; In terms of multiple polarization parameters calculation, based on the omnidirectional polarization inversion model is built, a variety of polarization parameter images are obtained and the precision of inversion is to be improve obviously; In terms of polarization image fusion , using fuzzy integral and sparse representation, the multiple polarization parameters adaptive optimal fusion method is given, and the targets detection in complex scene is completed by using the clustering image segmentation algorithm based on fractal characters; In polarization image tracking, the average displacement polarization image characteristics of auxiliary particle filtering fusion tracking algorithm is put forward to achieve the smooth tracking of moving targets. Finally, the polarization information parsing method is applied to the polarization imaging detection of typical targets such as the camouflage target, the fog and latent fingerprints.

Cometary impact and amino acid survival - Chemical kinetics and thermochemistry

USGS Publications Warehouse

Ross, D.S.

2006-01-01

The Arrhenius parameters for the initiating reactions in butane thermolysis and the formation of soot, reliable to at least 3000 K, have been applied to the question of the survival of amino acids in cometary impacts on early Earth. The pressure/temperature/time course employed here was that developed in hydrocode simulations for kilometer-sized comets (Pierazzo and Chyba, 1999), with attention to the track below 3000 K where it is shown that potential stabilizing effects of high pressure become unimportant kinetically. The question of survival can then be considered without the need for assignment of activation volumes and the related uncertainties in their application to extreme conditions. The exercise shows that the characteristic times for soot formation in the interval fall well below the cooling periods for impacts ranging from fully vertical down to about 9?? above horizontal. Decarboxylation, which emerges as more rapid than soot formation below 2000-3000 K, continues further down to extremely narrow impact angles, and accordingly cometa??ry delivery of amino acids to early Earth is highly unlikely. ?? 2006 American Chemical Society.

Optical properties of marine stratocumulus clouds modified by ships

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, M.D.; Radke, L.F.; Hobbs, P.V.

1993-02-20

The angular distribution of scattered radiation deep within a cloud layer was measured in marine stratocumulus clouds modified by the emissions from ships. These observations, obtained at 13 discrete wavelengths between 0.5 and 2.3 [mu]m, were acquired as the University of Washington C-131A aircraft flew through a pair of roughly parallel ship track signatures produced in clouds off the coast of southern California on July 10, 1987. In the first of these ship tracks, the nadir (upwelling) intensity increased from 40 to 110 W m[sup [minus]2] [mu]m[sup [minus]1] sr[sup [minus]1] at 0.744 [mu]m. The second ship track produced a lessmore » dramatic, but more uniform, increase in the upwelling intensity. In contrast, the nadir intensity at 2.20 [mu]m decreased from 1 to 0.13 W m[sup [minus]2] [mu]m[sup [minus]1] sr[sup [minus]1] in the first ship track and to 0.6 W m[sup [minus]2] [mu]m[sup [minus]1] sr[sup [minus]1] in the second ship track. The relative angular distribution of the intensity field at each wavelength was used to determine the similarity parameter, and hence single scattering albedo, of the cloud using the diffusion domain method. Besides the spectral similarity parameter, these measurements provide a good estimate of the optical depth of the cloud layer both above and below the aircraft. Results of this analysis are presented for a 120-km section of marine stratocumulus cloud including both ship tracks. This analysis shows that the total optical thickness of the cloud layer increased in the ship tracks, in contrast to the similarity parameter which decreased. The decrease in absorption was a direct consequence of the reduction in cloud droplet size that occurred within the ship tracks. 34 refs., 11 figs., 2 tabs.« less

Track analysis of laser-illuminated etched track detectors using an opto-digital imaging system

NASA Astrophysics Data System (ADS)

Eghan, Moses J.; Buah-Bassuah, Paul K.; Oppon, Osborne C.

2007-11-01

An opto-digital imaging system for counting and analysing tracks on a LR-115 detector is described. One batch of LR-115 track detectors was irradiated with Am-241 for a determined period and distance for linearity test and another batch was exposed to radon gas. The laser-illuminated etched track detector area was imaged, digitized and analysed by the system. The tracks that were counted on the opto-digital system with the aid of media cybernetics software as well as spark gap counter showed comparable track density results ranging between 1500 and 2750 tracks cm-2 and 65 tracks cm-2 in the two different batch detector samples with 0.5% and 1% track counts, respectively. Track sizes of the incident alpha particles from the radon gas on the LR-115 detector demonstrating different track energies are statistically and graphically represented. The opto-digital imaging system counts and measures other track parameters at an average process time of 3-5 s.

Agent-based modeling of malaria vectors: the importance of spatial simulation.

PubMed

Bomblies, Arne

2014-07-03

The modeling of malaria vector mosquito populations yields great insight into drivers of malaria transmission at the village scale. Simulation of individual mosquitoes as "agents" in a distributed, dynamic model domain may be greatly beneficial for simulation of spatial relationships of vectors and hosts. In this study, an agent-based model is used to simulate the life cycle and movement of individual malaria vector mosquitoes in a Niger Sahel village, with individual simulated mosquitoes interacting with their physical environment as well as humans. Various processes that are known to be epidemiologically important, such as the dependence of parity on flight distance between developmental habitat and blood meal hosts and therefore spatial relationships of pools and houses, are readily simulated using this modeling paradigm. Impacts of perturbations can be evaluated on the basis of vectorial capacity, because the interactions between individuals that make up the population- scale metric vectorial capacity can be easily tracked for simulated mosquitoes and human blood meal hosts, without the need to estimate vectorial capacity parameters. As expected, model results show pronounced impacts of pool source reduction from larvicide application and draining, but with varying degrees of impact depending on the spatial relationship between pools and human habitation. Results highlight the importance of spatially-explicit simulation that can model individuals such as in an agent-based model. The impacts of perturbations on village scale malaria transmission depend on spatial locations of individual mosquitoes, as well as the tracking of relevant life cycle events and characteristics of individual mosquitoes. This study demonstrates advantages of using an agent-based approach for village-scale mosquito simulation to address questions in which spatial relationships are known to be important.

Impact Capacity Reduction in Railway Prestressed Concrete Sleepers with Surface Abrasions

NASA Astrophysics Data System (ADS)

Ngamkhanong, Chayut; Li, Dan; Kaewunruen, Sakdirat

2017-10-01

Railway sleepers (also called ‘railroad tie’ in North America) embedded in ballasted railway tracks are a main part of railway track structures. Its important role is to transfer the loads evenly from the rails to a wider area of ballast bed and to secure rail gauge and enable safe passages of rolling stocks. By nature, railway infrastructure is nonlinear, evidenced by its behaviours, geometry and alignment, wheel-rail contact and operational parameters such as tractive efforts. Based on our critical review, the dynamic behaviour of railway sleepers has not been fully investigated, especially when the sleepers are deteriorated by excessive wears. In fact, the ballast angularity causes differential abrasions on the soffit or bottom surface of sleepers (especially at railseat zone). Furthermore, in sharp curves and rapid gradient change, longitudinal and lateral dynamics of rails increase the likelihood of railseat abrasions in concrete sleepers due to the unbalanced loading conditions. This paper presents a structural capacity of concrete sleepers under dynamic transient loading. The modified compression field theory for ultimate strength design of concrete sleepers under impact loading will be highlighted in this study. The influences of surface abrasions, including surface abrasion and soffit abrasion, on the dynamic behaviour of prestressed concrete sleepers, are firstly highlighted. The outcome of this study will improve the rail maintenance and inspection criteria in order to establish appropriate and sensible remote track condition monitoring network in practice. Moreover, this study will also improve the understanding of the fundamental dynamic behaviour of prestressed concrete sleepers with surface abrasions. The insight into these behaviours will not only improve safety and reliability of railway infrastructure but will enhance the structural safety of other concrete structures.

Energy awareness for supercapacitors using Kalman filter state-of-charge tracking

NASA Astrophysics Data System (ADS)

Nadeau, Andrew; Hassanalieragh, Moeen; Sharma, Gaurav; Soyata, Tolga

2015-11-01

Among energy buffering alternatives, supercapacitors can provide unmatched efficiency and durability. Additionally, the direct relation between a supercapacitor's terminal voltage and stored energy can improve energy awareness. However, a simple capacitive approximation cannot adequately represent the stored energy in a supercapacitor. It is shown that the three branch equivalent circuit model provides more accurate energy awareness. This equivalent circuit uses three capacitances and associated resistances to represent the supercapacitor's internal SOC (state-of-charge). However, the SOC cannot be determined from one observation of the terminal voltage, and must be tracked over time using inexact measurements. We present: 1) a Kalman filtering solution for tracking the SOC; 2) an on-line system identification procedure to efficiently estimate the equivalent circuit's parameters; and 3) experimental validation of both parameter estimation and SOC tracking for 5 F, 10 F, 50 F, and 350 F supercapacitors. Validation is done within the operating range of a solar powered application and the associated power variability due to energy harvesting. The proposed techniques are benchmarked against the simple capacitive model and prior parameter estimation techniques, and provide a 67% reduction in root-mean-square error for predicting usable buffered energy.

SU-E-T-562: Motion Tracking Optimization for Conformal Arc Radiotherapy Plans: A QUASAR Phantom Based Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Z; Wang, I; Yao, R

Purpose: This study is to use plan parameters optimization (Dose rate, collimator angle, couch angle, initial starting phase) to improve the performance of conformal arc radiotherapy plans with motion tracking by increasing the plan performance score (PPS). Methods: Two types of 3D conformal arc plans were created based on QUASAR respiratory motion phantom with spherical and cylindrical targets. Sinusoidal model was applied to the MLC leaves to generate motion tracking plans. A MATLAB program was developed to calculate PPS of each plan (ranges from 0–1) and optimize plan parameters. We first selected the dose rate for motion tracking plans andmore » then used simulated annealing algorithm to search for the combination of the other parameters that resulted in the plan of the maximal PPS. The optimized motion tracking plan was delivered by Varian Truebeam Linac. In-room cameras and stopwatch were used for starting phase selection and synchronization between phantom motion and plan delivery. Gaf-EBT2 dosimetry films were used to measure the dose delivered to the target in QUASAR phantom. Dose profiles and Truebeam trajectory log files were used for plan delivery performance evaluation. Results: For spherical target, the maximal PPS (PPSsph) of the optimized plan was 0.79: (Dose rate: 500MU/min, Collimator: 90°, Couch: +10°, starting phase: 0.83π). For cylindrical target, the maximal PPScyl was 0.75 (Dose rate: 300MU/min, Collimator: 87°, starting phase: 0.97π) with couch at 0°. Differences of dose profiles between motion tracking plans (with the maximal and the minimal PPS) and 3D conformal plans were as follows: PPSsph=0.79: %ΔFWHM: 8.9%, %Dmax: 3.1%; PPSsph=0.52: %ΔFWHM: 10.4%, %Dmax: 6.1%. PPScyl=0.75: %ΔFWHM: 4.7%, %Dmax: 3.6%; PPScyl=0.42: %ΔFWHM: 12.5%, %Dmax: 9.6%. Conclusion: By achieving high plan performance score through parameters optimization, we can improve target dose conformity of motion tracking plan by decreasing total MLC leaf travel distance and leaf speed.« less

Impact analyses for negative flexural responses (hogging) in railway prestressed concrete sleepers

NASA Astrophysics Data System (ADS)

Kaewunruen, S.; Ishida, T.; Remennikov, AM

2016-09-01

By nature, ballast interacts with railway concrete sleepers in order to provide bearing support to track system. Most train-track dynamic models do not consider the degradation of ballast over time. In fact, the ballast degradation causes differential settlement and impact forces acting on partial and unsupported tracks. Furthermore, localised ballast breakages underneath railseat increase the likelihood of centrebound cracks in concrete sleepers due to the unbalanced support under sleepers. This paper presents a dynamic finite element model of a standard-gauge concrete sleeper in a track system, taking into account the tensionless nature of ballast support. The finite element model was calibrated using static and dynamic responses in the past. In this paper, the effects of centre-bound ballast support on the impact behaviours of sleepers are highlighted. In addition, it is the first to demonstrate the dynamic effects of sleeper length on the dynamic design deficiency in concrete sleepers. The outcome of this study will benefit the rail maintenance criteria of track resurfacing in order to restore ballast profile and appropriate sleeper/ballast interaction.

The impact trajectory of asteroid 2008 TC3

NASA Astrophysics Data System (ADS)

Farnocchia, Davide; Jenniskens, Peter; Robertson, Darrel K.; Chesley, Steven R.; Dimare, Linda; Chodas, Paul W.

2017-09-01

The impact of asteroid 2008 TC3 was an unprecedented event-the first ever predicted impact of a near-Earth object. When it was first detected about 20 h before impact, 2008 TC3 was still farther away than the Moon. Once it was recognized as an impactor and announced as such, 2008 TC3 began to receive considerable attention from astronomical observers. Using the unprecedented dataset of nearly 900 astrometric observations and the latest observation debiasing and weighting techniques, we estimate the precise trajectory of 2008 TC3 and its impact ground track. At the entry point into the atmosphere, the 3-σ formal uncertainty in predicted position is an ellipse only 1.4 km × 0.15 km in size. The locations of the many meteorites recovered from the desert floor mark the asteroid's actual ground track and provide a unique opportunity to validate trajectory models. We find that the second-order zonal harmonics of the Earth gravity field moves the ground track by more than 1 km and the location along the ground track by more than 2 km, while non-zonal and higher order harmonics change the impact prediction by less than 20 m. The contribution of atmospheric drag to the trajectory of 2008 TC3 is similar to the numerical integration error level, a few meters, down to an altitude of 50 km. Integrating forward to lower altitudes and ignoring the break-up of 2008 TC3, atmospheric drag causes an along-track deviation that can be as large as a few kilometers at sea level.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crijns, Wouter, E-mail: wouter.crijns@uzleuven.be; Depuydt, Tom; Haustermans, Karin

Purpose: To evaluate three different plan adaptation strategies using 3D film-stack dose measurements of both focal boost and hypofractionated prostate VMAT treatments. The adaptation strategies (a couch shift, geometric tracking, and dosimetric tracking) were applied for three realistic intrafraction prostate motions. Methods: A focal boost (35 × 2.2 and 35 × 2.7 Gy) and a hypofractionated (5 × 7.25 Gy) prostate VMAT plan were created for a heterogeneous phantom that allows for internal prostate motion. For these plans geometric tracking and dosimetric tracking were evaluated by ionization chamber (IC) point dose measurements (zero-D) and measurements using a stack of EBT3more » films (3D). The geometric tracking applied translations, rotations, and scaling of the MLC aperture in response to realistic prostate motions. The dosimetric tracking additionally corrected the monitor units to resolve variations due to difference in depth, tissue heterogeneity, and MLC-aperture. The tracking was based on the positions of four fiducial points only. The film measurements were compared to the gold standard (i.e., IC measurements) and the planned dose distribution. Additionally, the 3D measurements were converted to dose volume histograms, tumor control probability, and normal tissue complication probability parameters (DVH/TCP/NTCP) as a direct estimate of clinical relevance of the proposed tracking. Results: Compared to the planned dose distribution, measurements without prostate motion and tracking showed already a reduced homogeneity of the dose distribution. Adding prostate motion further blurs the DVHs for all treatment approaches. The clinical practice (no tracking) delivered the dose distribution inside the PTV but off target (CTV), resulting in boost dose errors up to 10%. The geometric and dosimetric tracking corrected the dose distribution’s position. Moreover, the dosimetric tracking could achieve the planned boost DVH, but not the DVH of the more homogeneously irradiated prostate. A drawback of both the geometric and dosimetric tracking was a reduced MLC blocking caused by the rotational component of the MLC aperture corrections. Because of the used CTV to PTV margins and the high doses in the considered fractionation schemes, the TCP differed less than 0.02 from the planned value for all targets and all correction methods. The rectal NTCP constraints, however, could not be realized using any of these methods. Conclusions: The geometric and dosimetric tracking use only a limited input, but they deposit the dose distribution with higher geometric accuracy than the clinical practice. The latter case has boost dose errors up to 10%. The increased accuracy has a modest impact [Δ(NT)CP < 0.02] because of the applied margins and the high dose levels used. To allow further margin reduction tracking methods are vital. The proposed methodology could further be improved by implementing a rotational correction using collimator rotations.« less

Parametric Analysis and Safety Concepts of CWR Track Buckling.

DOT National Transportation Integrated Search

1993-12-01

The report presents a comprehensive study of continuous welded rail (CWR) track buckling strength as influenced by the range of all key parameters such as the lateral, torsional and longitudinal resistance, vehicle loads, etc. The parametric study pr...

TTI (Texas Transportation Institute) track/dynamometer study. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reineman, M.; Thompson, G.

1983-01-01

Seven passenger cars and one light truck were operated over the EPA urban and highway driving cycles to compare fuel economy measurements obtained on a test track with the fuel economy results obtained on a chassis dynamometer. The test program was designed to duplicate, as closely as possible, the track force loading (as determined by standard EPA road coastdown procedures) on the dynamometer. Experimental parameters which were investigated included loading differences between front- and rear-wheel drive vehicles, volumetric versus carbon balance fuel measurement techniques, coupled versus uncoupled roll dynamometer tests, and curved track versus straight track coastdowns.

Application of RFID in the area of agricultural products quality traceability and tracking and the anti-collision algorithm

NASA Astrophysics Data System (ADS)

Wang, Zu-liang; Zhang, Ting; Xie, Shi-yang

2017-01-01

In order to improve the agricultural tracing efficiency and reduce tracking and monitoring cost, agricultural products quality tracking and tracing based on Radio-Frequency Identification(RFID) technology is studied, then tracing and tracking model is set up. Three-layer structure model is established to realize the high quality of agricultural products traceability and tracking. To solve the collision problems between multiple RFID tags and improve the identification efficiency a new reservation slot allocation mechanism is proposed. And then we analyze and optimize the parameter by numerical simulation method.

Looping tracks associated with tropical cyclones approaching an isolated mountain. Part I: Essential parameters

NASA Astrophysics Data System (ADS)

Huang, Yi-Chih; Lin, Yuh-Lang

2018-06-01

Essential parameters for making a looping track when a westward-moving tropical cyclone (TC) approaches a mesoscale mountain are investigated by examining several key nondimensional control parameters with a series of systematic, idealized numerical experiments, such as U/ Nh, V max/ Nh, U/ fL x , V max/ fR, h/ L x , and R/ L y . Here U is the uniform zonal wind velocity, N the Brunt-Vaisala frequency, h the mountain height, f the Coriolis parameter, V max the maximum tangential velocity at a radius of R from the cyclone center and L x is the halfwidth of the mountain in the east-west direction. It is found that looping tracks (a) tend to occur under small U/ Nh and U/ fL x , moderate h/ L x , and large V max/ Nh, which correspond to slow movement (leading to subgeostrophic flow associated with strong orographic blocking), moderate steepness, and strong tangential wind associated with TC vortex; (b) are often accompanied by an area of perturbation high pressure to the northeast of the mountain, which lasts for only a short period; and (c) do not require the existence of a northerly jet. The nondimensional control parameters are consolidated into a TC looping index (LI), {U2 R2 }/{V_{max 2 hLy }} , which is tested by several historical looping and non-looping typhoons approaching Taiwan's Central Mountain Range (CMR) from east or southeast. It is found that LI < 0.0125 may serve as a criterion for looping track to occur.

Integrated direct/indirect adaptive robust motion trajectory tracking control of pneumatic cylinders

NASA Astrophysics Data System (ADS)

Meng, Deyuan; Tao, Guoliang; Zhu, Xiaocong

2013-09-01

This paper studies the precision motion trajectory tracking control of a pneumatic cylinder driven by a proportional-directional control valve. An integrated direct/indirect adaptive robust controller is proposed. The controller employs a physical model based indirect-type parameter estimation to obtain reliable estimates of unknown model parameters, and utilises a robust control method with dynamic compensation type fast adaptation to attenuate the effects of parameter estimation errors, unmodelled dynamics and disturbances. Due to the use of projection mapping, the robust control law and the parameter adaption algorithm can be designed separately. Since the system model uncertainties are unmatched, the recursive backstepping technology is adopted to design the robust control law. Extensive comparative experimental results are presented to illustrate the effectiveness of the proposed controller and its performance robustness to parameter variations and sudden disturbances.

Optimization of the microcable and detector parameters towards low noise in the STS readout system

NASA Astrophysics Data System (ADS)

Kasinski, Krzysztof; Kleczek, Rafal; Schmidt, Christian J.

2015-09-01

Successful operation of the Silicon Tracking System requires charge measurement of each hit with equivalent noise charge lower than 1000 e- rms. Detector channels will not be identical, they will be constructed accordingly to the estimated occupancy, therefore for the readout electronics, detector system will exhibit various parameters. This paper presents the simulation-based study on the required microcable (trace width, dielectric material), detector (aluminum strip resistance) and external passives' (decoupling capacitors) parameters in the Silicon Tracking System. Studies will be performed using a front-end electronics (charge sensitive amplifier with shaper) designed for the power budget of 10 mA/channel.

Bayesian approach to analyzing holograms of colloidal particles.

PubMed

Dimiduk, Thomas G; Manoharan, Vinothan N

2016-10-17

We demonstrate a Bayesian approach to tracking and characterizing colloidal particles from in-line digital holograms. We model the formation of the hologram using Lorenz-Mie theory. We then use a tempered Markov-chain Monte Carlo method to sample the posterior probability distributions of the model parameters: particle position, size, and refractive index. Compared to least-squares fitting, our approach allows us to more easily incorporate prior information about the parameters and to obtain more accurate uncertainties, which are critical for both particle tracking and characterization experiments. Our approach also eliminates the need to supply accurate initial guesses for the parameters, so it requires little tuning.

Star tracking method based on multiexposure imaging for intensified star trackers.

PubMed

Yu, Wenbo; Jiang, Jie; Zhang, Guangjun

2017-07-20

The requirements for the dynamic performance of star trackers are rapidly increasing with the development of space exploration technologies. However, insufficient knowledge of the angular acceleration has largely decreased the performance of the existing star tracking methods, and star trackers may even fail to track under highly dynamic conditions. This study proposes a star tracking method based on multiexposure imaging for intensified star trackers. The accurate estimation model of the complete motion parameters, including the angular velocity and angular acceleration, is established according to the working characteristic of multiexposure imaging. The estimation of the complete motion parameters is utilized to generate the predictive star image accurately. Therefore, the correct matching and tracking between stars in the real and predictive star images can be reliably accomplished under highly dynamic conditions. Simulations with specific dynamic conditions are conducted to verify the feasibility and effectiveness of the proposed method. Experiments with real starry night sky observation are also conducted for further verification. Simulations and experiments demonstrate that the proposed method is effective and shows excellent performance under highly dynamic conditions.

The Lateral Tracking Control for the Intelligent Vehicle Based on Adaptive PID Neural Network.

PubMed

Han, Gaining; Fu, Weiping; Wang, Wen; Wu, Zongsheng

2017-05-30

The intelligent vehicle is a complicated nonlinear system, and the design of a path tracking controller is one of the key technologies in intelligent vehicle research. This paper mainly designs a lateral control dynamic model of the intelligent vehicle, which is used for lateral tracking control. Firstly, the vehicle dynamics model (i.e., transfer function) is established according to the vehicle parameters. Secondly, according to the vehicle steering control system and the CARMA (Controlled Auto-Regression and Moving-Average) model, a second-order control system model is built. Using forgetting factor recursive least square estimation (FFRLS), the system parameters are identified. Finally, a neural network PID (Proportion Integral Derivative) controller is established for lateral path tracking control based on the vehicle model and the steering system model. Experimental simulation results show that the proposed model and algorithm have the high real-time and robustness in path tracing control. This provides a certain theoretical basis for intelligent vehicle autonomous navigation tracking control, and lays the foundation for the vertical and lateral coupling control.

The Lateral Tracking Control for the Intelligent Vehicle Based on Adaptive PID Neural Network

PubMed Central

Han, Gaining; Fu, Weiping; Wang, Wen; Wu, Zongsheng

2017-01-01

The intelligent vehicle is a complicated nonlinear system, and the design of a path tracking controller is one of the key technologies in intelligent vehicle research. This paper mainly designs a lateral control dynamic model of the intelligent vehicle, which is used for lateral tracking control. Firstly, the vehicle dynamics model (i.e., transfer function) is established according to the vehicle parameters. Secondly, according to the vehicle steering control system and the CARMA (Controlled Auto-Regression and Moving-Average) model, a second-order control system model is built. Using forgetting factor recursive least square estimation (FFRLS), the system parameters are identified. Finally, a neural network PID (Proportion Integral Derivative) controller is established for lateral path tracking control based on the vehicle model and the steering system model. Experimental simulation results show that the proposed model and algorithm have the high real-time and robustness in path tracing control. This provides a certain theoretical basis for intelligent vehicle autonomous navigation tracking control, and lays the foundation for the vertical and lateral coupling control. PMID:28556817

Low-Energy Impacts onto Lunar Regolith Simulant

NASA Astrophysics Data System (ADS)

Seward, Laura M.; Colwell, J.; Mellon, M.; Stemm, B.

2012-10-01

Low-Energy Impacts onto Lunar Regolith Simulant Laura M. Seward1, Joshua E. Colwell1, Michael T. Mellon2, and Bradley A. Stemm1, 1Department of Physics, University of Central Florida, Orlando, Florida, 2Southwest Research Institute, Boulder, Colorado. Impacts and cratering in space play important roles in the formation and evolution of planetary bodies. Low-velocity impacts and disturbances to planetary regolith are also a consequence of manned and robotic exploration of planetary bodies such as the Moon, Mars, and asteroids. We are conducting a program of laboratory experiments to study low-velocity impacts of 1 to 5 m/s into JSC-1 lunar regolith simulant, JSC-Mars-1 Martian regolith simulant, and silica targets under 1 g. We use direct measurement of ejecta mass and high-resolution video tracking of ejecta particle trajectories to derive ejecta mass velocity distributions. Additionally, we conduct similar experiments under microgravity conditions in a laboratory drop tower and on parabolic aircraft with velocities as low as 10 cm/s. We wish to characterize and understand the collision parameters that control the outcome of low-velocity impacts into regolith, including impact velocity, impactor mass, target shape and size distribution, regolith depth, target relative density, and crater depth, and to experimentally determine the functional dependencies of the outcomes of low-velocity collisions (ejecta mass and ejecta velocities) on the controlling parameters of the collision. We present results from our ongoing study showing the positive correlation between impact energy and ejecta mass. The total ejecta mass is also dependent on the packing density (porosity) of the regolith. We find that ejecta mass velocity fits a power-law or broken power-law distribution. Our goal is to understand the physics of ejecta production and regolith compaction in low-energy impacts and experimentally validate predictive models for dust flow and deposition. We will present our results from one-g and microgravity impact experiments.

Analysis of Railroad Track Maintenance Expenditures for Class I Railroads 1962-1977

DOT National Transportation Integrated Search

1982-02-01

This study investigates the decision-making process for railroad track maintenance (T/M) expenditures. The objectives are to (1) describe how Federal track safety standards have influenced this process and (2) try to predict the impact of changes in ...

Impact of a scholarly track on quality of residency program applicants.

PubMed

Celebi, Julie M; Nguyen, Cathina T; Sattler, Amelia L; Stevens, Michael B; Lin, Steven Y

2016-11-01

It is generally believed that residency programs offering scholarly tracks attract higher quality applicants, although there is little evidence of this in the literature. We explored the impact of a clinician-educator track on the quality of applicants to our residency program by comparing the volume and characteristics of applicants before (2008-2011) and after (2012-2015) the track was introduced. The total number of applications received was compared between the pre-track and post-track years. Among interviewees, data on United States Medical Licensing Examination (USMLE) Step 1 scores, Step 2 Clinical Knowledge (CK) scores, Medical Student Performance Evaluation (MSPE) scores, and proportion of candidates with an advanced degree (e.g. MPH, PhD) were compared. An online survey was administered to all interviewees in 2014-2015 to measure interest in the track. The total number of applications to the residency program increased significantly from the pre-track to the post-track years. Compared to the pre-track years, interviewees during the post-track years had statistically higher USMLE Step 1 and Step 2 CK scores, better MSPE scores, and were more likely to have an advanced degree. Two-thirds of survey respondents reported that the track increased their interest in the residency program. A residency clinician-educator track may be associated with increased overall interest from applicants, higher application volume, and better measures of applicant quality based on USMLE scores, MSPE scores, and proportion of candidates with an advanced degree. Residency programs may consider a potential increase in the quality of their applicants as an added benefit of offering a scholarly track.

Autonomous & Adaptive Oceanographic Feature Tracking on Board Autonomous Underwater Vehicles

DTIC Science & Technology

2015-02-01

44 3.6 Tracking the Marine ermocline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 3.6.1 ermocline Definition ...intelligent autonomy algorithms to adapt the vehicle’s motion to changes in the environment, effectively seeking out and tracking an oceanographic...interface, H is the mean water depth, and f is the Coriolis parameter (twice the earth’s angular velocity about its vertical axis) [38]. at is, the

Efficient Spatiotemporal Clutter Rejection and Nonlinear Filtering-based Dim Resolved and Unresolved Object Tracking Algorithms

NASA Astrophysics Data System (ADS)

Tartakovsky, A.; Tong, M.; Brown, A. P.; Agh, C.

2013-09-01

We develop efficient spatiotemporal image processing algorithms for rejection of non-stationary clutter and tracking of multiple dim objects using non-linear track-before-detect methods. For clutter suppression, we include an innovative image alignment (registration) algorithm. The images are assumed to contain elements of the same scene, but taken at different angles, from different locations, and at different times, with substantial clutter non-stationarity. These challenges are typical for space-based and surface-based IR/EO moving sensors, e.g., highly elliptical orbit or low earth orbit scenarios. The algorithm assumes that the images are related via a planar homography, also known as the projective transformation. The parameters are estimated in an iterative manner, at each step adjusting the parameter vector so as to achieve improved alignment of the images. Operating in the parameter space rather than in the coordinate space is a new idea, which makes the algorithm more robust with respect to noise as well as to large inter-frame disturbances, while operating at real-time rates. For dim object tracking, we include new advancements to a particle non-linear filtering-based track-before-detect (TrbD) algorithm. The new TrbD algorithm includes both real-time full image search for resolved objects not yet in track and joint super-resolution and tracking of individual objects in closely spaced object (CSO) clusters. The real-time full image search provides near-optimal detection and tracking of multiple extremely dim, maneuvering objects/clusters. The super-resolution and tracking CSO TrbD algorithm provides efficient near-optimal estimation of the number of unresolved objects in a CSO cluster, as well as the locations, velocities, accelerations, and intensities of the individual objects. We demonstrate that the algorithm is able to accurately estimate the number of CSO objects and their locations when the initial uncertainty on the number of objects is large. We demonstrate performance of the TrbD algorithm both for satellite-based and surface-based EO/IR surveillance scenarios.

Analysis and design of nonlinear resonances via singularity theory

NASA Astrophysics Data System (ADS)

Cirillo, G. I.; Habib, G.; Kerschen, G.; Sepulchre, R.

2017-03-01

Bifurcation theory and continuation methods are well-established tools for the analysis of nonlinear mechanical systems subject to periodic forcing. We illustrate the added value and the complementary information provided by singularity theory with one distinguished parameter. While tracking bifurcations reveals the qualitative changes in the behaviour, tracking singularities reveals how structural changes are themselves organised in parameter space. The complementarity of that information is demonstrated in the analysis of detached resonance curves in a two-degree-of-freedom system.

Cross-sectional evaluation of visuomotor tracking performance following subconcussive head impacts.

PubMed

Brokaw, E B; Fine, M S; Kindschi, K E; Santago Ii, A C; Lum, P S; Higgins, M

2018-01-01

Repeated mild traumatic brain injury (mTBI) has been associated with increased risk of degenerative neurological disorders. While the effects of mTBI and repeated injury are known, studies have only recently started examining repeated subconcussive impacts, impacts that do not result in a clinically diagnosed mTBI. In these studies, repeated subconcussive impacts have been connected to cognitive performance and brain imaging changes. Recent research suggests that performance on a visuomotor tracking (VMT) task may help improve the identification of mTBI. The goal of this study was to investigate if VMT performance is sensitive to the cumulative effect of repeated subconcussive head impacts in collegiate men's lacrosse players. A cross-sectional, prospective study was completed with eleven collegiate men's lacrosse players. Participants wore helmet-mounted sensors and completed VMT and reaction time assessments. The relationship between cumulative impact metrics and VMT metrics were investigated. In this study, VMT performance correlated with repeated subconcussive head impacts; individuals approached clinically diagnosed mTBI-like performance as the cumulative rotational velocity they experienced increased. This suggests that repeated subconcussive impacts can result in measurable impairments and indicates that visuomotor tracking performance may be a useful tool for monitoring the effects of repeated subconcussive impacts.

Simultaneous tracking and regulation visual servoing of wheeled mobile robots with uncalibrated extrinsic parameters

NASA Astrophysics Data System (ADS)

Lu, Qun; Yu, Li; Zhang, Dan; Zhang, Xuebo

2018-01-01

This paper presentsa global adaptive controller that simultaneously solves tracking and regulation for wheeled mobile robots with unknown depth and uncalibrated camera-to-robot extrinsic parameters. The rotational angle and the scaled translation between the current camera frame and the reference camera frame, as well as the ones between the desired camera frame and the reference camera frame can be calculated in real time by using the pose estimation techniques. A transformed system is first obtained, for which an adaptive controller is then designed to accomplish both tracking and regulation tasks, and the controller synthesis is based on Lyapunov's direct method. Finally, the effectiveness of the proposed method is illustrated by a simulation study.

Trajectory tracking and backfitting techniques against theater ballistic missiles

NASA Astrophysics Data System (ADS)

Hutchins, Robert G.; Britt, Patrick T.

1999-10-01

Since the SCUD launches in the Gulf War, theater ballistic missile (TBM) systems have become a growing concern for the US military. Detection, fast track initiation, backfitting for launch point determination, and tracking and engagement during boost phase or shortly after booster cutoff are goals that grow in importance with the proliferation of weapons of mass destruction. This paper focuses on track initiation and backfitting techniques, as well as extending some earlier results on tracking a TBM during boost phase cutoff. Results indicate that Kalman techniques are superior to third order polynomial extrapolations in estimating the launch point, and that some knowledge of missile parameters, especially thrust, is extremely helpful in track initiation.

Thermal signature characteristics of vehicle/terrain interaction disturbances: implications for battlefield vehicle classification.

PubMed

Eastes, John W; Mason, George L; Kusinger, Alan E

2004-05-01

Thermal emissivity spectra (8-14 microm) of track impressions/background were determined in conjunction with operation of six military vehicle types, T-72 and M1 Tanks, an M2 Bradley Fighting Vehicle, a 5-ton truck, a D7 tractor, and a High Mobility Multipurpose Wheeled Vehicle (HMMWV), over diverse soil surfaces to determine if vehicle type could be related to track thermal signatures. Results suggest soil compaction and fragmentation/pulverization are primary parameters affecting track signatures and that soil and vehicle/terrain-contact type determine which parameter dominates. Steel-tracked vehicles exert relatively low ground-contact pressure but tend to fragment/pulverize soil more so than do rubber-tired vehicles, which tend mainly to compact. In quartz-rich, lean clay soil tracked vehicles produced impressions with spectral contrast of the quartz reststrahlen features decreased from that of the background. At the same time, 5-ton truck tracks exhibited increased contrast on the same surface, suggesting that steel tracks fragmented soil while rubber tires mainly produced compaction. The structure of materials such as sand and moist clay-rich river sediment makes them less subject to further fragmentation/pulverization; thus, compaction was the main factor affecting signatures in these media, and both tracked and wheeled vehicles created impressions with increased spectral contrast on these surfaces. These results suggest that remotely sensed thermal signatures could differentiate tracked and wheeled vehicles on terrain in many areas of the world of strategic interest. Significant applications include distinguishing visually/spectrally identical lightweight decoys from actual threat vehicles.

SU-G-BRA-15: Dosimetric Evaluation of Dynamic Tumor Tracking Radiation Therapy Using Digital Phantom: A Study On Margin and Desired Accuracy of Tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uchida, T; Osanai, M; Homma, N

2016-06-15

Purpose: Dynamic tumor tracking radiation therapy can potentially reduce internal margin without prolongation of irradiation time. However, dynamic tumor tracking technique requires an extra margin (tracking margin, TM) for the uncertainty of tumor localization, prediction, and beam repositioning. The purpose of this study was to evaluate a dosimetric impact caused by TM. Methods: We used 4D XCAT to create 9 digital phantom datasets of different tumor size and motion range: tumor diameter TD=(1, 3, 5) cm and motion range MR=(1, 2, 3) cm. For each dataset, respiratory gating (30%–70% phase) and tumor tracking treatment plans were created using 8-field 3D-CRTmore » by 4D dose calculation implemented in RayStation. The dose constraint was based on RTOG0618. For the tracking plan, TMs of (0, 2.5, 5) mm were considered by surrounding a normal setup margin: SM=5 mm. We calculated V20 of normal lung to evaluate the dosimetric impact for each case, and estimated an equivalent TM that affects the same impact on V20 obtained by the gated plan. Results: The equivalent TMs for (TD=1 cm, MR=2 cm), (TD=1 cm, MR=3 cm), (TD=5 cm, MR=2 cm), and (TD=5 cm, MR=3 cm) were estimated as 1.47 mm, 3.95 mm, 1.04 mm, and 2.13 mm, respectively. The larger the tumor size, the equivalent TM became smaller. On the other hand, the larger the motion range, the equivalent TM was found to be increased. Conclusion: Our results showed the equivalent TM changes depending on tumor size and motion range. The tracking plan with TM less than the equivalent TM achieves a dosimetric impact better than the gated plan in less treatment time. This study was partially supported by JSPS Kakenhi and Varian Medical Systems.« less

Procedures for minimizing the effects of high solar activity on satellite tracking and ephemeris generation

NASA Technical Reports Server (NTRS)

Bredvik, Gordon D.

1990-01-01

We are currently experiencing a period of high solar radiation combined with wide short-term fluctuations in the radiation. The short-term fluctuations, especially when combined with highly energetic solar flares, can adversely affect the mission of U.S. Space Command's Space Surveillance Center (SSC) which catalogs and tracks the satellites in orbit around the Earth. Rapidly increasing levels of solar electromagnetic and/or particle radiation (solar wind) causes atmospheric warming, which, in turn, causes the upper-most portions of the atmosphere to expand outward, into the regime of low altitude satellites. The increased drag on satellites from this expansion can cause large, unmodeled, in-track displacements, thus undermining the SSC's ability to track and predict satellite position. On 13 March 1989, high solar radiation levels, combined with a high-energy solar flare, caused an exceptional amount of short-term atmospheric warming. The SSC temporarily lost track of over 1300 low altitude satellites--nearly half of the low altitude satellite population. Observational data on satellites that became lost during the days following the 13 March 'solar event' was analyzed and compared with the satellites' last element set prior to the event (referred to as a geomagnetic storm because of the large increase in magnetic flux in the upper atmosphere). The analysis led to a set of procedures for reducing the impact of future geomagnetic storms. These procedures adjust selected software limit parameters in the differential correction of element sets and in the observation association process and must be manually initiated at the onset of a geomagnetic storm. Sensor tasking procedures must be adjusted to ensure that a minimum of four observations per day are received for low altitude satellites. These procedures have been implemented and, thus far, appear to be successful in minimizing the effect of subsequent geomagnetic storms on satellite tracking and ephemeris computation.

Tropical cyclone track Analysis over Indian Coast Using Spatio-Temporal data-mining

NASA Astrophysics Data System (ADS)

Mohapatra, Gyanendranath; Manjunath, Swetha; Behera, Sasmita; Mohanty, Pratap Kumar

2015-04-01

Tropical cyclones are a natural hazard which largely affects the lives and property with its destructive wind and heavy rainfall. Fluctuations in the frequency and intensity complicate the detection of long-term trends and play an important role in the global climate system; therefore understanding and predicting tropical cyclones track, intensity, and landfall location is of both societal and scientific significance. In this study a data-mining approach is being used to analyze the tropical cyclone track both in the temporal and spatial scale. Basically, the Indian coast line is divided into four zones viz. north east, south east in the eastern side adjoining Bay of Bengal and North west and south west in the western side adjoining Arabian sea as these coastal areas are very much vulnerable for disaster due to maximum number of landfall of Tropical Cyclones. The track and landfall associated with all the cyclones are clustered based on their intensity (Severe, moderate and low) and landfall location. The analyses are carried out for landfall location and the extent of track separately for the events happening in two seasons i.e. pre-monsoon and post-monsoon period. Along with categorization of intensity, trend analysis of track and the targeted zone of maximum damage also been studied. Algorithms are being developed for potential resilient and impact assessment of the parameters associated with cyclone disaster in the coastal region of India. One of the important objectives of this present work is also the identification of most disaster prone coastal area and becoming a part of the information support system during the cyclone period. Based on the statistics like mean, Standard Deviation, regression and correlation analysis, an index is developed which determines the level of damage and vulnerability along the coastal region. This index can be used for the early warning system of particular coastal areas for the preparedness and mitigation of future cyclone events.

Alligators and crocodiles as indicators for restoration of Everglades ecosystems

USGS Publications Warehouse

Mazzotti, Frank J.; Best, G. Ronnie; Brandt, Laura A.; Cherkiss, Michael S.; Jeffery, Brian M.; Rice, Kenneth G.

2009-01-01

Alligators and crocodiles integrate biological impacts of hydrological operations, affecting them at all life stages through three key aspects of Everglades ecology: (1) food webs, (2) diversity and productivity, and (3) freshwater flow. Responses of crocodilians are directly related to suitability of environmental conditions and hydrologic change. Correlations between biological responses and environmental conditions contribute to an understanding of species' status and trends over time. Positive or negative trends of crocodilian populations relative to hydrologic changes permit assessment of positive or negative trends in restoration. The crocodilian indicator uses monitoring parameters (performance measures) that have been shown to be both effective and efficient in tracking trends. The alligator component uses relative density (reported as an encounter rate), body condition, and occupancy rates of alligator holes; the crocodile component uses juvenile growth and hatchling survival. We hypothesize that these parameters are correlated with hydrologic conditions including depth, duration, timing, spatial extent and water quality. Salinity is a critical parameter in estuarine habitats. Assessments of parameters defined for crocodilian performance measures support these hypotheses. Alligators and crocodiles are the charismatic megafauna of the Everglades. They are both keystone and flagship species to which the public can relate. In addition, the parameters used to track trends are easy to understand. They provide answers to the following questions: How has the number of alligators or crocodiles changed? Are the animals fatter or thinner than they should be? Are the animals in the places (in terms of habitat and geography) where they should be? As surely as there is no other Everglades, no other single species defines the Everglades as does the American alligator. The Everglades is the only place in the world where both alligators and crocodiles exist. Crocodilians clearly respond to changes in hydrologic parameters of management interest. These relationships are easy to communicate and mean something to managers, decision makers, and the public. Having crocodilians on the list of system-wide, general indicators provides us with one of the most powerful tools we have to communicate progress of ecosystem restoration in Greater Everglades ecosystems to diverse audiences.

Intelligent tuning method of PID parameters based on iterative learning control for atomic force microscopy.

PubMed

Liu, Hui; Li, Yingzi; Zhang, Yingxu; Chen, Yifu; Song, Zihang; Wang, Zhenyu; Zhang, Suoxin; Qian, Jianqiang

2018-01-01

Proportional-integral-derivative (PID) parameters play a vital role in the imaging process of an atomic force microscope (AFM). Traditional parameter tuning methods require a lot of manpower and it is difficult to set PID parameters in unattended working environments. In this manuscript, an intelligent tuning method of PID parameters based on iterative learning control is proposed to self-adjust PID parameters of the AFM according to the sample topography. This method gets enough information about the output signals of PID controller and tracking error, which will be used to calculate the proper PID parameters, by repeated line scanning until convergence before normal scanning to learn the topography. Subsequently, the appropriate PID parameters are obtained by fitting method and then applied to the normal scanning process. The feasibility of the method is demonstrated by the convergence analysis. Simulations and experimental results indicate that the proposed method can intelligently tune PID parameters of the AFM for imaging different topographies and thus achieve good tracking performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impact of random pointing and tracking errors on the design of coherent and incoherent optical intersatellite communication links

NASA Technical Reports Server (NTRS)

Chen, Chien-Chung; Gardner, Chester S.

1989-01-01

Given the rms transmitter pointing error and the desired probability of bit error (PBE), it can be shown that an optimal transmitter antenna gain exists which minimizes the required transmitter power. Given the rms local oscillator tracking error, an optimum receiver antenna gain can be found which optimizes the receiver performance. The impact of pointing and tracking errors on the design of direct-detection pulse-position modulation (PPM) and heterodyne noncoherent frequency-shift keying (NCFSK) systems are then analyzed in terms of constraints on the antenna size and the power penalty incurred. It is shown that in the limit of large spatial tracking errors, the advantage in receiver sensitivity for the heterodyne system is quickly offset by the smaller antenna gain and the higher power penalty due to tracking errors. In contrast, for systems with small spatial tracking errors, the heterodyne system is superior because of the higher receiver sensitivity.

Shifts in Geochemical Parameters and Greenhouse Gas Fluxes following Insect-Induced Tree Mortality

NASA Astrophysics Data System (ADS)

Brouillard, B.; Mikkelson, K. M.; Berryman, E.; Sharp, J.; Leonard, L.; Vega, M.

2016-12-01

Extensive insect infestations and resultant expansive tree mortality are occurring globally due in part to warmer temperatures and persistent drought. These forest disturbances are expected to cause shifts in the biogeochemical cycle due to the cessation of below ground root outputs, changes in soil microbial communities, hydrologic perturbations, and altered woody material deposits to the forest floor. To better understand biogeochemical alterations and resolve potentially conflicting findings, we studied a lodgepole pine forest recently impacted by mountain pine beetles to determine the response of subsurface geochemical parameters and gaseous flux to the effects of surrounding tree mortality. While many parameters were found to be significantly different under recently killed trees compared to their healthy counterparts (pH, soil moisture, C/N-species), notable biogeochemically relevant parameters displayed shifts that tracked with the level of surrounding tree mortality. For instance, aromatic carbon (TSUVA) and CO2 respiration were found to have an increasing linear response under grey trees as the surrounding tree mortality within an 8m radius also increased. Rather than a linear increase, ammonium and nitrogen associated bacterial communities displayed a threshold effect, not increasing until a certain level of tree mortality of approximately 40% was surpassed. Gas flux was also correlated to measured parameters in three near surface soil horizons to determine drivers of CO2 and N2O release and their interactions with biogeochemical cycles. Collectively, these results aid in elucidating the extent of forest mortality required to overcome compensatory terrestrial biogeochemical processes. A heightened understanding of these shifts will aid the scientific and resource management community through enhanced predictive understanding of greenhouse gas release or potential water quality impacts following forest disturbance.

Target tracking system based on preliminary and precise two-stage compound cameras

NASA Astrophysics Data System (ADS)

Shen, Yiyan; Hu, Ruolan; She, Jun; Luo, Yiming; Zhou, Jie

2018-02-01

Early detection of goals and high-precision of target tracking is two important performance indicators which need to be balanced in actual target search tracking system. This paper proposed a target tracking system with preliminary and precise two - stage compound. This system using a large field of view to achieve the target search. After the target was searched and confirmed, switch into a small field of view for two field of view target tracking. In this system, an appropriate filed switching strategy is the key to achieve tracking. At the same time, two groups PID parameters are add into the system to reduce tracking error. This combination way with preliminary and precise two-stage compound can extend the scope of the target and improve the target tracking accuracy and this method has practical value.

Cell Mergers and Their Impact on Cloud-to-Ground Lightning Over the Houston Area

NASA Technical Reports Server (NTRS)

Gauthier, Michael L.; Petersen, Walter A.; Carey, Lawrence D.

2009-01-01

A previous hypothesis advanced from observational studies such as METROMEX suggests that the intensity, frequency, and organization of cumulus convection may be impacted by the forcing of enhanced merger activity downstream of urban zones. A resulting corollary is that cities may exert an indirect anthropogenic forcing of parameters related to convection and associated phenomena such as lightning and precipitation. This paper investigates the urban merger hypothesis by examining the role of convective cell mergers on the existence and persistence of the Houston lightning "anomaly", a local maximum in cloud-to-ground (CG) lightning activity documented to exist over and east of Houston. Using eight summer seasons of peak columnar radar reflectivity, CG lightning data and a cell-tracking algorithm, a two-dimensional cell merger climatology is created for portions of eastern Texas and Louisiana. Results from the tracking and analysis of over 3.8 million cells indicate that merger-driven enhancements in convection induce a positive response (O 46%) in ground-flash densities throughout the domain, with areas of enhanced lightning typically being co-located with areas of enhanced merger activity. However, while mergers over the Houston area (relative to elsewhere in the domain) do result in more vigorous convective cells that produce larger CG flash densities, we find that CG lightning contributions due to mergers are distributed similarly throughout the domain. Hence while we demonstrate that cell mergers do greatly impact the production of lightning, the urban cell merger hypothesis does not uniquely explain the presence of a local lightning maximum near and downstream of Houston.

An approach for modeling the influence of wheel tractor loads and vibration frequencies on soil compaction

NASA Astrophysics Data System (ADS)

Verotti, M.; Servadio, P.; Belfiore, N. P.; Bergonzoli, S.

2012-04-01

Both soil compaction and ground vibration are forms of environmental degradation that may be understood in the context of the vehicle-soil interaction process considered (Hildebrand et al., 2008). The transit of tractors on agricultural soil is often the main cause of soil compaction increasing. As known, this can be a serious problems for tillage and sowing and therefore the influence of all the affecting factors have been extensively studied in the last decades in order to understand their impact on the biosystem. There are factors related to the climate, namely to the rainfalls and temperature, and many others. Hence, it is not simple to figure out a complete model for predicting an index of compaction, for a given situation. Soil compaction models are important tools for controlling soil compaction due to agricultural field traffic and they are potentially useful technique to provide information concerning correct soil management. By means of such models, strategies and recommendations for prevention of soil compaction may be developed and specific advice may be given to farmers and advisers. In order to predict field wheeled and tracked vehicle performance, some empirical methods, used for off-road vehicle, were applied by Servadio (2010) on agricultural soil. The empirical indexes included, besides the soil strength, the load carried by the tire or track, some technical characteristics of the tire or track of the vehicle (tire or track width, tire or track wheel diameter, unloaded tire section height, number of wheel station in one track, tire deflection, total length of the belt track, the track pitch) as well as the vehicle passes. They have been validated with the tests results of agricultural vehicles over a range of soil in central Italy. Among the parameters which affect soil compaction, the water content of the soil, the axle load and number of vehicle passes proved to be the most important ones. The present paper concerns mainly vehicle-soil-man interaction. In particular, a model based on elasto-visco-plastic concentrated parameters, with multiple degrees of freedom, will be used in order to build a method for detecting a soil damage index, especially expressed in terms of increasing of soil compaction. Besides the axle load, the model will take into account the frequency of the vibrations that the vehicle is transmitting to the soil. Such model expresses a numerical value for the transmissibility coefficient and also allows evaluating the damage at the surface and on the bulk medium where the agricultural crops initially develop. Key words: vehicle-soil interaction, vibration, compaction, models. Acknowledgements This work was carried out under the auspices of the special project "Sceneries of adaptation of the Italian agriculture to the climatic changes" (AGROSCENARI) of the Agricultural Research Council, and Italian Ministry of the Agricultural and Forestry Politics.

Logistic Mixed Models to Investigate Implicit and Explicit Belief Tracking.

PubMed

Lages, Martin; Scheel, Anne

2016-01-01

We investigated the proposition of a two-systems Theory of Mind in adults' belief tracking. A sample of N = 45 participants predicted the choice of one of two opponent players after observing several rounds in an animated card game. Three matches of this card game were played and initial gaze direction on target and subsequent choice predictions were recorded for each belief task and participant. We conducted logistic regressions with mixed effects on the binary data and developed Bayesian logistic mixed models to infer implicit and explicit mentalizing in true belief and false belief tasks. Although logistic regressions with mixed effects predicted the data well a Bayesian logistic mixed model with latent task- and subject-specific parameters gave a better account of the data. As expected explicit choice predictions suggested a clear understanding of true and false beliefs (TB/FB). Surprisingly, however, model parameters for initial gaze direction also indicated belief tracking. We discuss why task-specific parameters for initial gaze directions are different from choice predictions yet reflect second-order perspective taking.

Analysis of Air Traffic Track Data with the AutoBayes Synthesis System

NASA Technical Reports Server (NTRS)

Schumann, Johann Martin Philip; Cate, Karen; Lee, Alan G.

2010-01-01

The Next Generation Air Traffic System (NGATS) is aiming to provide substantial computer support for the air traffic controllers. Algorithms for the accurate prediction of aircraft movements are of central importance for such software systems but trajectory prediction has to work reliably in the presence of unknown parameters and uncertainties. We are using the AutoBayes program synthesis system to generate customized data analysis algorithms that process large sets of aircraft radar track data in order to estimate parameters and uncertainties. In this paper, we present, how the tasks of finding structure in track data, estimation of important parameters in climb trajectories, and the detection of continuous descent approaches can be accomplished with compact task-specific AutoBayes specifications. We present an overview of the AutoBayes architecture and describe, how its schema-based approach generates customized analysis algorithms, documented C/C++ code, and detailed mathematical derivations. Results of experiments with actual air traffic control data are discussed.

Control of Systems With Slow Actuators Using Time Scale Separation

NASA Technical Reports Server (NTRS)

Stepanyan, Vehram; Nguyen, Nhan

2009-01-01

This paper addresses the problem of controlling a nonlinear plant with a slow actuator using singular perturbation method. For the known plant-actuator cascaded system the proposed scheme achieves tracking of a given reference model with considerably less control demand than would otherwise result when using conventional design techniques. This is the consequence of excluding the small parameter from the actuator dynamics via time scale separation. The resulting tracking error is within the order of this small parameter. For the unknown system the adaptive counterpart is developed based on the prediction model, which is driven towards the reference model by the control design. It is proven that the prediction model tracks the reference model with an error proportional to the small parameter, while the prediction error converges to zero. The resulting closed-loop system with all prediction models and adaptive laws remains stable. The benefits of the approach are demonstrated in simulation studies and compared to conventional control approaches.

Earth's gravity field to the eighteenth degree and geocentric coordinates for 104 stations from satellite and terrestrial data

NASA Technical Reports Server (NTRS)

Gaposchkin, E. M.

1973-01-01

Geodetic parameters describing the earth's gravity field and the positions of satellite-tracking stations in a geocentric reference frame were computed. These parameters were estimated by means of a combination of five different types of data: routine and simultaneous satellite observations, observations of deep-space probes, measurements of terrestrial gravity, and surface-triangulation data. The combination gives better parameters than does any subset of data types. The dynamic solution used precision-reduced Baker-Nunn observations and laser range data of 25 satellites. Data from the 49-station National Oceanic and Atmospheric Administration BC-4 network, the 19-station Smithsonian Astrophysical Observatory Baker-Nunn network, and independent camera stations were employed in the geometrical solution. Data from the tracking of deep-space probes were converted to relative longitudes and distances to the earth's axis of rotation of the tracking stations. Surface-gravity data in the form of 550-km squares were derived from 19,328 1 deg X 1 deg mean gravity anomalies.

Irradiation control parameters for computer-assisted laser photocoagulation of the retina

NASA Astrophysics Data System (ADS)

Naess, Espen; Molvik, Torstein; Barrett, Steven F.; Wright, Cameron H. G.; de Graaf, Peter W.

2001-06-01

A system for robotically assisted retinal surgery has been developed to rapidly and safely place lesions on the retina for photocoagulation therapy. This system provides real- time, motion stabilized lesion placement for typical irradiation times of 100 ms. The system consists of three main subsystems: a global, digital-based tracking subsystem; a fast, local analog tracking subsystem; and a confocal reflectance subsystem to control lesion parameters dynamically. We have reported on these subsystems in previous SPIE presentations. This paper concentrates on the development of the second hybrid system prototype. Considerable progress has been made toward reducing the footprint of the optical system, simplifying the user interface, fully characterizing the analog tracking system and using measurable lesion reflectance growth parameters to develop a noninvasive method to infer lesion depth. This method will allow dynamic control of laser dosimetry to provide similar lesions across the non-uniform retinal surface. These system improvements and progress toward a clinically significant system are covered in detail within this paper.

Parameter estimation in a human operator describing function model for a two-dimensional tracking task

NASA Technical Reports Server (NTRS)

Vanlunteren, A.

1977-01-01

A previously described parameter estimation program was applied to a number of control tasks, each involving a human operator model consisting of more than one describing function. One of these experiments is treated in more detail. It consisted of a two dimensional tracking task with identical controlled elements. The tracking errors were presented on one display as two vertically moving horizontal lines. Each loop had its own manipulator. The two forcing functions were mutually independent and consisted each of 9 sine waves. A human operator model was chosen consisting of 4 describing functions, thus taking into account possible linear cross couplings. From the Fourier coefficients of the relevant signals the model parameters were estimated after alignment, averaging over a number of runs and decoupling. The results show that for the elements in the main loops the crossover model applies. A weak linear cross coupling existed with the same dynamics as the elements in the main loops but with a negative sign.

SU-G-JeP1-10: Feasibility of CyberKnife Tracking Using the Previously-Implanted Permanent Brachytherapy Seed Cloud

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, J; Cunha, J; Sudhyadhom, A

Purpose: Robotic radiosurgery is a salvage treatment option for patients with recurrent prostate cancer. We explored the feasibility of tracking the bolus of permanent prostate implants (PPI) using image recognition software optimized to track spinal anatomy. Methods: Forty-five inert iodine seeds were implanted into a gelatin-based prostate phantom. Four superficial gold seeds were inserted to provide ground-truth alignment. A CT scan of the phantom (120 kVp, 1 mm slice thickness) was acquired and a single-energy iterative metal artifact reduction (MAR) algorithm was used to enhance the quality of the DRR used for tracking. CyberKnife treatment plans were generated from themore » MAR CT and regular CT (no-MAR) using spine tracking. The spine-tracking grid was centered on the bolus of seeds and resized to encompass the full seed cloud. A third plan was created from the regular CT scan, using fiducial tracking based on the 4 superficial gold seeds with identical align-center coordinates. The phantom was initially aligned using the fiducial-tracking plan. Then the MAR and no-MAR spine-tracking plans were loaded without moving the phantom. Differences in couch correction parameters were recorded in the case of perfect alignment and after the application of known rotations and translations (roll/pitch of 2 degrees; translations XYZ of 2 cm). Results: The spine tracking software was able to lock on to the bolus of seeds and provide couch corrections both in the MAR and no-MAR plans. In all cases, differences in the couch correction parameters from fiducial alignment were <0.5 mm in translations and <1 degree in rotations. Conclusion: We were able to successfully track the bolus of seeds with the spine-tracking grid in phantom experiments. For clinical applications, further investigation and developments to adapt the spine-tracking algorithm to optimize for PPI seed cloud tracking is needed to provide reliable tracking in patients. One of the authors (MD) has received research support and speaker honoraria from Accuray.« less

Advanced tracking systems design and analysis

NASA Technical Reports Server (NTRS)

Potash, R.; Floyd, L.; Jacobsen, A.; Cunningham, K.; Kapoor, A.; Kwadrat, C.; Radel, J.; Mccarthy, J.

1989-01-01

The results of an assessment of several types of high-accuracy tracking systems proposed to track the spacecraft in the National Aeronautics and Space Administration (NASA) Advanced Tracking and Data Relay Satellite System (ATDRSS) are summarized. Tracking systems based on the use of interferometry and ranging are investigated. For each system, the top-level system design and operations concept are provided. A comparative system assessment is presented in terms of orbit determination performance, ATDRSS impacts, life-cycle cost, and technological risk.

A parameterization of nuclear track profiles in CR-39 detector

NASA Astrophysics Data System (ADS)

Azooz, A. A.; Al-Nia'emi, S. H.; Al-Jubbori, M. A.

2012-11-01

In this work, the empirical parameterization describing the alpha particles’ track depth in CR-39 detectors is extended to describe longitudinal track profiles against etching time for protons and alpha particles. MATLAB based software is developed for this purpose. The software calculates and plots the depth, diameter, range, residual range, saturation time, and etch rate versus etching time. The software predictions are compared with other experimental data and with results of calculations using the original software, TRACK_TEST, developed for alpha track calculations. The software related to this work is freely downloadable and performs calculations for protons in addition to alpha particles. Program summary Program title: CR39 Catalog identifier: AENA_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENA_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Copyright (c) 2011, Aasim Azooz Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met • Redistributions of source code must retain the above copyright, this list of conditions and the following disclaimer. • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution This software is provided by the copyright holders and contributors “as is” and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. In no event shall the copyright owner or contributors be liable for any direct, indirect, incidental, special, exemplary, or consequential damages (including, but not limited to, procurement of substitute goods or services; loss of use, data, or profits; or business interruption) however caused and on any theory of liability, whether in contract, strict liability, or tort (including negligence or otherwise) arising in any way out of the use of this software, even if advised of the possibility of such damage. No. of lines in distributed program, including test data, etc.: 15598 No. of bytes in distributed program, including test data, etc.: 3933244 Distribution format: tar.gz Programming language: MATLAB. Computer: Any Desktop or Laptop. Operating system: Windows 1998 or above (with MATLAB R13 or above installed). RAM: 512 Megabytes or higher Classification: 17.5. Nature of problem: A new semispherical parameterization of charged particle tracks in CR-39 SSNTD is carried out in a previous paper. This parameterization is developed here into a MATLAB based software to calculate the track length and track profile for any proton or alpha particle energy or etching time. This software is intended to compete with the TRACK_TEST [1] and TRACK_VISION [2] software currently in use by all people working in the field of SSNTD. Solution method: Based on fitting of experimental results of protons and alpha particles track lengths for various energies and etching times to a new semispherical formula with four free fitting parameters, the best set of energy independent parameters were found. These parameters are introduced into the software and the software is programmed to solve the set of equations to calculate the track depth, track etching rate as a function of both time and residual range for particles of normal and oblique incidence, the track longitudinal profile at both normal and oblique incidence, and the three dimensional track profile at normal incidence. Running time: 1-8 s on Pentium (4) 2 GHz CPU, 3 GB of RAM depending on the etching time value References: [1] ADWT_v1_0 Track_Test Computer program TRACK_TEST for calculating parameters and plotting profiles for etch pits in nuclear track materials. D. Nikezic, K.N. Yu Comput. Phys. Commun. 174(2006)160 [2] AEAF_v1_0 TRACK_VISION Computer program TRACK_VISION for simulating optical appearance of etched tracks in CR-39 nuclear track detectors. D. Nikezic, K.N. Yu Comput. Phys. Commun. 178(2008)591

Capturing Revolute Motion and Revolute Joint Parameters with Optical Tracking

NASA Astrophysics Data System (ADS)

Antonya, C.

2017-12-01

Optical tracking of users and various technical systems are becoming more and more popular. It consists of analysing sequence of recorded images using video capturing devices and image processing algorithms. The returned data contains mainly point-clouds, coordinates of markers or coordinates of point of interest. These data can be used for retrieving information related to the geometry of the objects, but also to extract parameters for the analytical model of the system useful in a variety of computer aided engineering simulations. The parameter identification of joints deals with extraction of physical parameters (mainly geometric parameters) for the purpose of constructing accurate kinematic and dynamic models. The input data are the time-series of the marker’s position. The least square method was used for fitting the data into different geometrical shapes (ellipse, circle, plane) and for obtaining the position and orientation of revolute joins.

Automated Glacier Surface Velocity using Multi-Image/Multi-Chip (MIMC) Feature Tracking

NASA Astrophysics Data System (ADS)

Ahn, Y.; Howat, I. M.

2009-12-01

Remote sensing from space has enabled effective monitoring of remote and inhospitable polar regions. Glacier velocity, and its variation in time, is one of the most important parameters needed to understand glacier dynamics, glacier mass balance and contribution to sea level rise. Regular measurements of ice velocity are possible from large and accessible satellite data set archives, such as ASTER and LANDSAT-7. Among satellite imagery, optical imagery (i.e. passive, visible to near-infrared band sensors) provides abundant data with optimal spatial resolution and repeat interval for tracking glacier motion at high temporal resolution. Due to massive amounts of data, computation of ice velocity from feature tracking requires 1) user-friendly interface, 2) minimum local/user parameter inputs and 3) results that need minimum editing. We focus on robust feature tracking, applicable to all currently available optical satellite imagery, that is ASTER, SPOT and LANDSAT etc. We introduce the MIMC (multiple images/multiple chip sizes) matching approach that does not involve any user defined local/empirical parameters except approximate average glacier speed. We also introduce a method for extracting velocity from LANDSAT-7 SLC-off data, which has 22 percent of scene data missing in slanted strips due to failure of the scan line corrector. We apply our approach to major outlet glaciers in west/east Greenland and assess our MIMC feature tracking technique by comparison with conventional correlation matching and other methods (e.g. InSAR).

Vision-based measurement for rotational speed by improving Lucas-Kanade template tracking algorithm.

PubMed

Guo, Jie; Zhu, Chang'an; Lu, Siliang; Zhang, Dashan; Zhang, Chunyu

2016-09-01

Rotational angle and speed are important parameters for condition monitoring and fault diagnosis of rotating machineries, and their measurement is useful in precision machining and early warning of faults. In this study, a novel vision-based measurement algorithm is proposed to complete this task. A high-speed camera is first used to capture the video of the rotational object. To extract the rotational angle, the template-based Lucas-Kanade algorithm is introduced to complete motion tracking by aligning the template image in the video sequence. Given the special case of nonplanar surface of the cylinder object, a nonlinear transformation is designed for modeling the rotation tracking. In spite of the unconventional and complex form, the transformation can realize angle extraction concisely with only one parameter. A simulation is then conducted to verify the tracking effect, and a practical tracking strategy is further proposed to track consecutively the video sequence. Based on the proposed algorithm, instantaneous rotational speed (IRS) can be measured accurately and efficiently. Finally, the effectiveness of the proposed algorithm is verified on a brushless direct current motor test rig through the comparison with results obtained by the microphone. Experimental results demonstrate that the proposed algorithm can extract accurately rotational angles and can measure IRS with the advantage of noncontact and effectiveness.

Modeling and Development of INS-Aided PLLs in a GNSS/INS Deeply-Coupled Hardware Prototype for Dynamic Applications

PubMed Central

Zhang, Tisheng; Niu, Xiaoji; Ban, Yalong; Zhang, Hongping; Shi, Chuang; Liu, Jingnan

2015-01-01

A GNSS/INS deeply-coupled system can improve the satellite signals tracking performance by INS aiding tracking loops under dynamics. However, there was no literature available on the complete modeling of the INS branch in the INS-aided tracking loop, which caused the lack of a theoretical tool to guide the selections of inertial sensors, parameter optimization and quantitative analysis of INS-aided PLLs. This paper makes an effort on the INS branch in modeling and parameter optimization of phase-locked loops (PLLs) based on the scalar-based GNSS/INS deeply-coupled system. It establishes the transfer function between all known error sources and the PLL tracking error, which can be used to quantitatively evaluate the candidate inertial measurement unit (IMU) affecting the carrier phase tracking error. Based on that, a steady-state error model is proposed to design INS-aided PLLs and to analyze their tracking performance. Based on the modeling and error analysis, an integrated deeply-coupled hardware prototype is developed, with the optimization of the aiding information. Finally, the performance of the INS-aided PLLs designed based on the proposed steady-state error model is evaluated through the simulation and road tests of the hardware prototype. PMID:25569751

Track propagation methods for the correlation of charged tracks with clusters in the calorimeter of the bar PANDA experiment

NASA Astrophysics Data System (ADS)

Nasawasd, T.; Simantathammakul, T.; Herold, C.; Stockmanns, T.; Ritman, J.; Kobdaj, C.

2018-02-01

To classify clusters of hits in the electromagnetic calorimeter (EMC) of bar PANDA (antiProton ANnihilation at DArmstadt), one has to match these EMC clusters with tracks of charged particles reconstructed from hits in the tracking system. Therefore the tracks are propagated to the surface of the EMC and associated with EMC clusters which are nearby and below a cut parameter. In this work, we propose a helix propagator to extrapolate the track from the Straw Tube Tracker (STT) to the inner surface of the EMC instead of the GEANE propagator which is already embedded within the PandaRoot computational framework. The results for both propagation methods show a similar quality, with a 30% gain in CPU time when using the helix propagator. We use Monte-Carlo truth information to compare the particle ID of the EMC clusters with the ID of the extrapolated points, thus deciding upon the correctness of the matches. By varying the cut parameter as a function of transverse momentum and particle type, our simulations show that the purity can be increased by 3-5% compared to the default value which is a constant cut in the bar PANDA simulation framework PandaRoot.

Guidance of Nonlinear Nonminimum-Phase Dynamic Systems

NASA Technical Reports Server (NTRS)

Devasia, Santosh

1996-01-01

The research work has advanced the inversion-based guidance theory for: systems with non-hyperbolic internal dynamics; systems with parameter jumps; and systems where a redesign of the output trajectory is desired. A technique to achieve output tracking for nonminimum phase linear systems with non-hyperbolic and near non-hyperbolic internal dynamics was developed. This approach integrated stable inversion techniques, that achieve exact-tracking, with approximation techniques, that modify the internal dynamics to achieve desirable performance. Such modification of the internal dynamics was used (a) to remove non-hyperbolicity which is an obstruction to applying stable inversion techniques and (b) to reduce large preactuation times needed to apply stable inversion for near non-hyperbolic cases. The method was applied to an example helicopter hover control problem with near non-hyperbolic internal dynamics for illustrating the trade-off between exact tracking and reduction of preactuation time. Future work will extend these results to guidance of nonlinear non-hyperbolic systems. The exact output tracking problem for systems with parameter jumps was considered. Necessary and sufficient conditions were derived for the elimination of switching-introduced output transient. While previous works had studied this problem by developing a regulator that maintains exact tracking through parameter jumps (switches), such techniques are, however, only applicable to minimum-phase systems. In contrast, our approach is also applicable to nonminimum-phase systems and leads to bounded but possibly non-causal solutions. In addition, for the case when the reference trajectories are generated by an exosystem, we developed an exact-tracking controller which could be written in a feedback form. As in standard regulator theory, we also obtained a linear map from the states of the exosystem to the desired system state, which was defined via a matrix differential equation.

Geocenter variations derived from a combined processing of LEO- and ground-based GPS observations

NASA Astrophysics Data System (ADS)

Männel, Benjamin; Rothacher, Markus

2017-08-01

GNSS observations provided by the global tracking network of the International GNSS Service (IGS, Dow et al. in J Geod 83(3):191-198, 2009) play an important role in the realization of a unique terrestrial reference frame that is accurate enough to allow a detailed monitoring of the Earth's system. Combining these ground-based data with GPS observations tracked by high-quality dual-frequency receivers on-board low earth orbiters (LEOs) is a promising way to further improve the realization of the terrestrial reference frame and the estimation of geocenter coordinates, GPS satellite orbits and Earth rotation parameters. To assess the scope of the improvement on the geocenter coordinates, we processed a network of 53 globally distributed and stable IGS stations together with four LEOs (GRACE-A, GRACE-B, OSTM/Jason-2 and GOCE) over a time interval of 3 years (2010-2012). To ensure fully consistent solutions, the zero-difference phase observations of the ground stations and LEOs were processed in a common least-squares adjustment, estimating all the relevant parameters such as GPS and LEO orbits, station coordinates, Earth rotation parameters and geocenter motion. We present the significant impact of the individual LEO and a combination of all four LEOs on the geocenter coordinates. The formal errors are reduced by around 20% due to the inclusion of one LEO into the ground-only solution, while in a solution with four LEOs LEO-specific characteristics are significantly reduced. We compare the derived geocenter coordinates w.r.t. LAGEOS results and external solutions based on GPS and SLR data. We found good agreement in the amplitudes of all components; however, the phases in x- and z-direction do not agree well.

Systematic effects in LOD from SLR observations

NASA Astrophysics Data System (ADS)

Bloßfeld, Mathis; Gerstl, Michael; Hugentobler, Urs; Angermann, Detlef; Müller, Horst

2014-09-01

Beside the estimation of station coordinates and the Earth’s gravity field, laser ranging observations to near-Earth satellites can be used to determine the rotation of the Earth. One parameter of this rotation is ΔLOD (excess Length Of Day) which describes the excess revolution time of the Earth w.r.t. 86,400 s. Due to correlations among the different parameter groups, it is difficult to obtain reliable estimates for all parameters. In the official ΔLOD products of the International Earth Rotation and Reference Systems Service (IERS), the ΔLOD information determined from laser ranging observations is excluded from the processing. In this paper, we study the existing correlations between ΔLOD, the orbital node Ω, the even zonal gravity field coefficients, cross-track empirical accelerations and relativistic accelerations caused by the Lense-Thirring and deSitter effect in detail using first order Gaussian perturbation equations. We found discrepancies due to different a priories by using different gravity field models of up to 1.0 ms for polar orbits at an altitude of 500 km and up to 40.0 ms, if the gravity field coefficients are estimated using only observations to LAGEOS 1. If observations to LAGEOS 2 are included, reliable ΔLOD estimates can be achieved. Nevertheless, an impact of the a priori gravity field even on the multi-satellite ΔLOD estimates can be clearly identified. Furthermore, we investigate the effect of empirical cross-track accelerations and the effect of relativistic accelerations of near-Earth satellites on ΔLOD. A total effect of 0.0088 ms is caused by not modeled Lense-Thirring and deSitter terms. The partial derivatives of these accelerations w.r.t. the position and velocity of the satellite cause very small variations (0.1 μs) on ΔLOD.

Calipso's Mission Design: Sun-Glint Avoidance Strategies

NASA Technical Reports Server (NTRS)

Mailhe, Laurie M.; Schiff, Conrad; Stadler, John H.

2004-01-01

CALIPSO will fly in formation with the Aqua spacecraft to obtain a coincident image of a portion of the Aqua/MODIS swath. Since MODIS pixels suffering sun-glint degradation are not processed, it is essential that CALIPSO only co- image the glint h e portion of the MODIS instrument swath. This paper presents sun-glint avoidance strategies for the CALIPSO mission. First, we introduce the Aqua sun-glint geometry and its relation to the CALIPSO-Aqua formation flying parameters. Then, we detail our implementation of the computation and perform a cross-track trade-space analysis. Finally, we analyze the impact of the sun-glint avoidance strategy on the spacecraft power and delta-V budget over the mission lifetime.

77 FR 25781 - Environmental Impact Statement; Washington, DC

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-01

... do not meet the needs of modern freight rail infrastructure due to its single track arrangement and the inability to accommodate double-stack intermodal container freight trains. The single-track... network that encompasses about 21,000 route miles of track in 23 states, the District of Columbia and the...

Implementation of an open-scenario, long-term space debris simulation approach

NASA Astrophysics Data System (ADS)

Stupl, J.; Nelson, B.; Faber, N.; Perez, A.; Carlino, R.; Yang, F.; Henze, C.; Karacalioglu, A.; O'Toole, C.; Swenson, J.

This paper provides a status update on the implementation of a flexible, long-term space debris simulation approach. The motivation is to build a tool that can assess the long-term impact of various options for debris-remediation, including the LightForce space debris collision avoidance scheme. State-of-the-art simulation approaches that assess the long-term development of the debris environment use either completely statistical approaches, or they rely on large time steps in the order of several (5-15) days if they simulate the positions of single objects over time. They cannot be easily adapted to investigate the impact of specific collision avoidance schemes or de-orbit schemes, because the efficiency of a collision avoidance maneuver can depend on various input parameters, including ground station positions, space object parameters and orbital parameters of the conjunctions and take place in much smaller timeframes than 5-15 days. For example, LightForce only changes the orbit of a certain object (aiming to reduce the probability of collision), but it does not remove entire objects or groups of objects. In the same sense, it is also not straightforward to compare specific de-orbit methods in regard to potential collision risks during a de-orbit maneuver. To gain flexibility in assessing interactions with objects, we implement a simulation that includes every tracked space object in LEO, propagates all objects with high precision, and advances with variable-sized time-steps as small as one second. It allows the assessment of the (potential) impact of changes to any object. The final goal is to employ a Monte Carlo approach to assess the debris evolution during the simulation time-frame of 100 years and to compare a baseline scenario to debris remediation scenarios or other scenarios of interest. To populate the initial simulation, we use the entire space-track object catalog in LEO. We then use a high precision propagator to propagate all objects over the entire simulation duration. If collisions are detected, the appropriate number of debris objects are created and inserted into the simulation framework. Depending on the scenario, further objects, e.g. due to new launches, can be added. At the end of the simulation, the total number of objects above a cut-off size and the number of detected collisions provide benchmark parameters for the comparison between scenarios. The simulation approach is computationally intensive as it involves ten thousands of objects; hence we use a highly parallel approach employing up to a thousand cores on the NASA Pleiades supercomputer for a single run. This paper describes our simulation approach, the status of its implementation, the approach in developing scenarios and examples of first test runs.

Visual-motor response of crewmen during a simulated 90-day space mission as measured by the critical task battery

NASA Technical Reports Server (NTRS)

Allen, R. W.; Jex, H. R.

1973-01-01

In order to test various components of a regenerative life support system and to obtain data on the physiological and psychological effects of long duration exposure to confinement in a space station atmosphere, four carefully screened young men were sealed in a space station simulator for 90 days and administered a tracking test battery. The battery included a clinical test (Critical Instability Task) designed to measure a subject's dynamic time delay, and a more conventional steady tracking task, during which dynamic response (describing functions) and performance measures were obtained. Good correlation was noted between the clinical critical instability scores and more detailed tracking parameters such as dynamic time delay and gain-crossover frequency. The levels of each parameter span the range observed with professional pilots and astronaut candidates tested previously. The chamber environment caused no significant decrement on the average crewman's dynamic response behavior, and the subjects continued to improve slightly in their tracking skills during the 90-day confinement period.

Laser Metal Deposition as Repair Technology for a Gas Turbine Burner Made of Inconel 718

NASA Astrophysics Data System (ADS)

Petrat, Torsten; Graf, Benjamin; Gumenyuk, Andrey; Rethmeier, Michael

Maintenance, repair and overhaul of components are of increasing interest for parts of high complexity and expensive manufacturing costs. In this paper a production process for laser metal deposition is presented, and used to repair a gas turbine burner of Inconel 718. Different parameters for defined track geometries were determined to attain a near net shape deposition with consistent build-up rate for changing wall thicknesses over the manufacturing process. Spot diameter, powder feed rate, welding velocity and laser power were changed as main parameters for a different track size. An optimal overlap rate for a constant layer height was used to calculate the best track size for a fitting layer width similar to the part dimension. Deviations in width and height over the whole build-up process were detected and customized build-up strategies for the 3D sequences were designed. The results show the possibility of a near net shape repair by using different track geometries with laser metal deposition.

Enhancement of tracking performance in electro-optical system based on servo control algorithm

NASA Astrophysics Data System (ADS)

Choi, WooJin; Kim, SungSu; Jung, DaeYoon; Seo, HyoungKyu

2017-10-01

Modern electro-optical surveillance and reconnaissance systems require tracking capability to get exact images of target or to accurately direct the line of sight to target which is moving or still. This leads to the tracking system composed of image based tracking algorithm and servo control algorithm. In this study, we focus on the servo control function to minimize the overshoot in the tracking motion and do not miss the target. The scheme is to limit acceleration and velocity parameters in the tracking controller, depending on the target state information in the image. We implement the proposed techniques by creating a system model of DIRCM and simulate the same environment, validate the performance on the actual equipment.

Intercomparison of mid latitude storm diagnostics (IMILAST)

NASA Astrophysics Data System (ADS)

Neu, U.

2009-04-01

Diagnostics of the observed and projection of the future changes of extratropical storms are a key issue e.g. for insurance companies, risk management and adaptation planning. Storm-associated damages are amongst the highest losses due to natural disasters in the mid-latitudes. Therefore the knowledge of the future variability and change in extratropical cyclone frequency, intensity and track locations is crucial for the strategic planning and minimization of the disaster impacts. Future changes in the total number of storms might be small but major signals could occur in the characteristics of cyclone life cycle such as intensity, life time, track locations. The quantification of such trends is not independent from the methodologies for storm track detection applied to observational data and models. Comparison of differences in cyclone characteristics obtained using different methods from a single data set may be as large as or even exceed the differences between the results derived from different data sets using a single methodology. Even more, the metrics used become particularly sensitive, resulting in the fact that scientific studies may find seemingly contradictory results based on the same datasets. For users of storm track analyses and projections the results are very difficult to interprete. Thus, it would be very helpful if the research community would provide information in a kind of "handbook" which contains definitions and a description of the available different identification and tracking schemes as well as of the parameters used for the quantification of cyclone activity. It cannot be expected that there is an optimum or standard scheme that fulfills all needs. Rather, a proper knowledge about advantages and restrictions of different schemes must be obtained to be able to provide a synthesis of results rather than puzzling the scientific and the general public with apparently contradicing statements. The project IMILAST aims at providing a systematic intercomparison of different methodologies and a comprehensive assessment of all types of uncertainties inherent in the mid-latitudinal storm tracking by comparing different methodologies with respect to data of different resolution (time and space) and limited areas, for both cyclone identification and cyclone tracking respectively.

Chaos synchronization and Nelder-Mead search for parameter estimation in nonlinear pharmacological systems: Estimating tumor antigenicity in a model of immunotherapy.

PubMed

Pillai, Nikhil; Craig, Morgan; Dokoumetzidis, Aristeidis; Schwartz, Sorell L; Bies, Robert; Freedman, Immanuel

2018-06-19

In mathematical pharmacology, models are constructed to confer a robust method for optimizing treatment. The predictive capability of pharmacological models depends heavily on the ability to track the system and to accurately determine parameters with reference to the sensitivity in projected outcomes. To closely track chaotic systems, one may choose to apply chaos synchronization. An advantageous byproduct of this methodology is the ability to quantify model parameters. In this paper, we illustrate the use of chaos synchronization combined with Nelder-Mead search to estimate parameters of the well-known Kirschner-Panetta model of IL-2 immunotherapy from noisy data. Chaos synchronization with Nelder-Mead search is shown to provide more accurate and reliable estimates than Nelder-Mead search based on an extended least squares (ELS) objective function. Our results underline the strength of this approach to parameter estimation and provide a broader framework of parameter identification for nonlinear models in pharmacology. Copyright © 2018 Elsevier Ltd. All rights reserved.

The dosimetric impact of inversely optimized arc radiotherapy plan modulation for real-time dynamic MLC tracking delivery.

PubMed

Falk, Marianne; Larsson, Tobias; Keall, Paul; Chul Cho, Byung; Aznar, Marianne; Korreman, Stine; Poulsen, Per; Munck Af Rosenschold, Per

2012-03-01

Real-time dynamic multileaf collimator (MLC) tracking for management of intrafraction tumor motion can be challenging for highly modulated beams, as the leaves need to travel far to adjust for target motion perpendicular to the leaf travel direction. The plan modulation can be reduced by using a leaf position constraint (LPC) that reduces the difference in the position of adjacent MLC leaves in the plan. The purpose of this study was to investigate the impact of the LPC on the quality of inversely optimized arc radiotherapy plans and the effect of the MLC motion pattern on the dosimetric accuracy of MLC tracking delivery. Specifically, the possibility of predicting the accuracy of MLC tracking delivery based on the plan modulation was investigated. Inversely optimized arc radiotherapy plans were created on CT-data of three lung cancer patients. For each case, five plans with a single 358° arc were generated with LPC priorities of 0 (no LPC), 0.25, 0.5, 0.75, and 1 (highest possible LPC), respectively. All the plans had a prescribed dose of 2 Gy × 30, used 6 MV, a maximum dose rate of 600 MU/min and a collimator angle of 45° or 315°. To quantify the plan modulation, an average adjacent leaf distance (ALD) was calculated by averaging the mean adjacent leaf distance for each control point. The linear relationship between the plan quality [i.e., the calculated dose distributions and the number of monitor units (MU)] and the LPC was investigated, and the linear regression coefficient as well as a two tailed confidence level of 95% was used in the evaluation. The effect of the plan modulation on the performance of MLC tracking was tested by delivering the plans to a cylindrical diode array phantom moving with sinusoidal motion in the superior-inferior direction with a peak-to-peak displacement of 2 cm and a cycle time of 6 s. The delivery was adjusted to the target motion using MLC tracking, guided in real-time by an infrared optical system. The dosimetric results were evaluated using gamma index evaluation with static target measurements as reference. The plan quality parameters did not depend significantly on the LPC (p ≥ 0.066), whereas the ALD depended significantly on the LPC (p < 0.001). The gamma index failure rate depended significantly on the ALD, weighted to the percentage of the beam delivered in each control point of the plan (ALD(w)) when MLC tracking was used (p < 0.001), but not for delivery without MLC tracking (p ≥ 0.342). The gamma index failure rate with the criteria of 2% and 2 mm was decreased from > 33.9% without MLC tracking to <31.4% (LPC 0) and <2.2% (LPC 1) with MLC tracking. The results indicate that the dosimetric robustness of MLC tracking delivery of an inversely optimized arc radiotherapy plan can be improved by incorporating leaf position constraints in the objective function without otherwise affecting the plan quality. The dosimetric robustness may be estimated prior to delivery by evaluating the ALD(w) of the plan.

Impacts of tracked vehicles on sediment from a desert soil

Treesearch

Erek H. Fuchs; Karl M. Wood; Tim L. Jones; Brent Racher

2003-01-01

Off-road military vehicle traffic is a major consideration in the management of military lands. The objective of this study was to determine the impacts of military tracked M1A1 heavy combat tank vehicles on sediment loss from runoff, surface plant cover, and surface microtopography in a desert military training environment. A randomized block design was used which had...

Keeping Learning on Track: A Case-Study of Formative Assessment Practice and Its Impact on Learning in Meridian School District

ERIC Educational Resources Information Center

Thum, Y. M.; Tarasawa, B.; Hegedus, A.; Yun, X.; Bowe, B.

2015-01-01

In partnership with Joint School District 2 in Meridian, Idaho, this theory-driven study assessed the impact of Keeping Learning on Track® (KLT™), a professional development program pioneered by Dylan Wiliam and his colleagues at the Educational Testing Service (ETS). A team of Northwest Evaluation Association™ (NWEA™) researchers surveyed…

An Empirical Human Controller Model for Preview Tracking Tasks.

PubMed

van der El, Kasper; Pool, Daan M; Damveld, Herman J; van Paassen, Marinus Rene M; Mulder, Max

2016-11-01

Real-life tracking tasks often show preview information to the human controller about the future track to follow. The effect of preview on manual control behavior is still relatively unknown. This paper proposes a generic operator model for preview tracking, empirically derived from experimental measurements. Conditions included pursuit tracking, i.e., without preview information, and tracking with 1 s of preview. Controlled element dynamics varied between gain, single integrator, and double integrator. The model is derived in the frequency domain, after application of a black-box system identification method based on Fourier coefficients. Parameter estimates are obtained to assess the validity of the model in both the time domain and frequency domain. Measured behavior in all evaluated conditions can be captured with the commonly used quasi-linear operator model for compensatory tracking, extended with two viewpoints of the previewed target. The derived model provides new insights into how human operators use preview information in tracking tasks.

Magnetic Resonance Imaging–Guided versus Surrogate-Based Motion Tracking in Liver Radiation Therapy: A Prospective Comparative Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paganelli, Chiara, E-mail: chiara.paganelli@polimi.it; Seregni, Matteo; Fattori, Giovanni

Purpose: This study applied automatic feature detection on cine–magnetic resonance imaging (MRI) liver images in order to provide a prospective comparison between MRI-guided and surrogate-based tracking methods for motion-compensated liver radiation therapy. Methods and Materials: In a population of 30 subjects (5 volunteers plus 25 patients), 2 oblique sagittal slices were acquired across the liver at high temporal resolution. An algorithm based on scale invariant feature transform (SIFT) was used to extract and track multiple features throughout the image sequence. The position of abdominal markers was also measured directly from the image series, and the internal motion of each featuremore » was quantified through multiparametric analysis. Surrogate-based tumor tracking with a state-of-the-art external/internal correlation model was simulated. The geometrical tracking error was measured, and its correlation with external motion parameters was also investigated. Finally, the potential gain in tracking accuracy relying on MRI guidance was quantified as a function of the maximum allowed tracking error. Results: An average of 45 features was extracted for each subject across the whole liver. The multi-parametric motion analysis reported relevant inter- and intrasubject variability, highlighting the value of patient-specific and spatially-distributed measurements. Surrogate-based tracking errors (relative to the motion amplitude) were were in the range 7% to 23% (1.02-3.57mm) and were significantly influenced by external motion parameters. The gain of MRI guidance compared to surrogate-based motion tracking was larger than 30% in 50% of the subjects when considering a 1.5-mm tracking error tolerance. Conclusions: Automatic feature detection applied to cine-MRI allows detailed liver motion description to be obtained. Such information was used to quantify the performance of surrogate-based tracking methods and to provide a prospective comparison with respect to MRI-guided radiation therapy, which could support the definition of patient-specific optimal treatment strategies.« less

Adaptive tracking control of a wheeled mobile robot via an uncalibrated camera system.

PubMed

Dixon, W E; Dawson, D M; Zergeroglu, E; Behal, A

2001-01-01

This paper considers the problem of position/orientation tracking control of wheeled mobile robots via visual servoing in the presence of parametric uncertainty associated with the mechanical dynamics and the camera system. Specifically, we design an adaptive controller that compensates for uncertain camera and mechanical parameters and ensures global asymptotic position/orientation tracking. Simulation and experimental results are included to illustrate the performance of the control law.

Data analysis-based autonomic bandwidth adjustment in software defined multi-vendor optical transport networks.

PubMed

Li, Yajie; Zhao, Yongli; Zhang, Jie; Yu, Xiaosong; Jing, Ruiquan

2017-11-27

Network operators generally provide dedicated lightpaths for customers to meet the demand for high-quality transmission. Considering the variation of traffic load, customers usually rent peak bandwidth that exceeds the practical average traffic requirement. In this case, bandwidth provisioning is unmetered and customers have to pay according to peak bandwidth. Supposing that network operators could keep track of traffic load and allocate bandwidth dynamically, bandwidth can be provided as a metered service and customers would pay for the bandwidth that they actually use. To achieve cost-effective bandwidth provisioning, this paper proposes an autonomic bandwidth adjustment scheme based on data analysis of traffic load. The scheme is implemented in a software defined networking (SDN) controller and is demonstrated in the field trial of multi-vendor optical transport networks. The field trial shows that the proposed scheme can track traffic load and realize autonomic bandwidth adjustment. In addition, a simulation experiment is conducted to evaluate the performance of the proposed scheme. We also investigate the impact of different parameters on autonomic bandwidth adjustment. Simulation results show that the step size and adjustment period have significant influences on bandwidth savings and packet loss. A small value of step size and adjustment period can bring more benefits by tracking traffic variation with high accuracy. For network operators, the scheme can serve as technical support of realizing bandwidth as metered service in the future.

Stardust Interstellar Preliminary Examination II: Curating the Interstellar Dust Collector, Picokeystones, and Sources of Impact Tracks

NASA Technical Reports Server (NTRS)

Frank, David R.; Westphal, Andrew J.; Zolensky, Michael E.; Gainsforth, Zack; Butterworth, Anna L.; Bastien, Ronald K.; Allen, Carlton; Anderson, David; Bechtel, Hans A.; Sandford, Scott A.

2013-01-01

We discuss the inherent difficulties that arise during "ground truth" characterization of the Stardust interstellar dust collector. The challenge of identifying contemporary interstellar dust impact tracks in aerogel is described within the context of background spacecraft secondaries and possible interplanetary dust particles and beta-meteoroids. In addition, the extraction of microscopic dust embedded in aerogel is technically challenging. Specifically, we provide a detailed description of the sample preparation techniques developed to address the unique goals and restrictions of the Interstellar Preliminary Exam. These sample preparation requirements and the scarcity of candidate interstellar impact tracks exacerbate the difficulties. We also illustrate the role of initial optical imaging with critically important examples, and summarize the overall processing of the collection to date.

An extended Kalman filter for mouse tracking.

PubMed

Choi, Hongjun; Kim, Mingi; Lee, Onseok

2018-05-19

Animal tracking is an important tool for observing behavior, which is useful in various research areas. Animal specimens can be tracked using dynamic models and observation models that require several types of data. Tracking mouse has several barriers due to the physical characteristics of the mouse, their unpredictable movement, and cluttered environments. Therefore, we propose a reliable method that uses a detection stage and a tracking stage to successfully track mouse. The detection stage detects the surface area of the mouse skin, and the tracking stage implements an extended Kalman filter to estimate the state variables of a nonlinear model. The changes in the overall shape of the mouse are tracked using an oval-shaped tracking model to estimate the parameters for the ellipse. An experiment is conducted to demonstrate the performance of the proposed tracking algorithm using six video images showing various types of movement, and the ground truth values for synthetic images are compared to the values generated by the tracking algorithm. A conventional manual tracking method is also applied to compare across eight experimenters. Furthermore, the effectiveness of the proposed tracking method is also demonstrated by applying the tracking algorithm with actual images of mouse. Graphical abstract.

Increasing vertical resolution in US models to improve track forecasts of Hurricane Joaquin with HWRF as an example

PubMed Central

Zhang, Banglin; Tallapragada, Vijay; Weng, Fuzhong; Liu, Qingfu; Sippel, Jason A.; Ma, Zaizhong; Bender, Morris A.

2016-01-01

The atmosphere−ocean coupled Hurricane Weather Research and Forecast model (HWRF) developed at the National Centers for Environmental Prediction (NCEP) is used as an example to illustrate the impact of model vertical resolution on track forecasts of tropical cyclones. A number of HWRF forecasting experiments were carried out at different vertical resolutions for Hurricane Joaquin, which occurred from September 27 to October 8, 2015, in the Atlantic Basin. The results show that the track prediction for Hurricane Joaquin is much more accurate with higher vertical resolution. The positive impacts of higher vertical resolution on hurricane track forecasts suggest that National Oceanic and Atmospheric Administration/NCEP should upgrade both HWRF and the Global Forecast System to have more vertical levels. PMID:27698121

B-spline based image tracking by detection

NASA Astrophysics Data System (ADS)

Balaji, Bhashyam; Sithiravel, Rajiv; Damini, Anthony; Kirubarajan, Thiagalingam; Rajan, Sreeraman

2016-05-01

Visual image tracking involves the estimation of the motion of any desired targets in a surveillance region using a sequence of images. A standard method of isolating moving targets in image tracking uses background subtraction. The standard background subtraction method is often impacted by irrelevant information in the images, which can lead to poor performance in image-based target tracking. In this paper, a B-Spline based image tracking is implemented. The novel method models the background and foreground using the B-Spline method followed by a tracking-by-detection algorithm. The effectiveness of the proposed algorithm is demonstrated.

Improving the nowcasting of precipitation in an Alpine region with an enhanced radar echo tracking algorithm

NASA Astrophysics Data System (ADS)

Mecklenburg, S.; Joss, J.; Schmid, W.

2000-12-01

Nowcasting for hydrological applications is discussed. The tracking algorithm extrapolates radar images in space and time. It originates from the pattern recognition techniques TREC (Tracking Radar Echoes by Correlation, Rinehart and Garvey, J. Appl. Meteor., 34 (1995) 1286) and COTREC (Continuity of TREC vectors, Li et al., Nature, 273 (1978) 287). To evaluate the quality of the extrapolation, a parameter scheme is introduced, able to distinguish between errors in the position and the intensity of the predicted precipitation. The parameters for the position are the absolute error, the relative error and the error of the forecasted direction. The parameters for the intensity are the ratio of the medians and the variations of the rain rate (ratio of two quantiles) between the actual and the forecasted image. To judge the overall quality of the forecast, the correlation coefficient between the forecasted and the actual radar image has been used. To improve the forecast, three aspects have been investigated: (a) Common meteorological attributes of convective cells, derived from a hail statistics, have been determined to optimize the parameters of the tracking algorithm. Using (a), the forecast procedure modifications (b) and (c) have been applied. (b) Small-scale features have been removed by using larger tracking areas and by applying a spatial and temporal smoothing, since problems with the tracking algorithm are mainly caused by small-scale/short-term variations of the echo pattern or because of limitations caused by the radar technique itself (erroneous vectors caused by clutter or shielding). (c) The searching area and the number of searched boxes have been restricted. This limits false detections, which is especially useful in stratiform precipitation and for stationary echoes. Whereas a larger scale and the removal of small-scale features improve the forecasted position for the convective precipitation, the forecast of the stratiform event is not influenced, but limiting the search area leads to a slightly better forecast. The forecast of the intensity is successful for both precipitation events. Forecasting the variation of the rain rate calls for further investigation. Applying COTREC improves the forecast of the convective precipitation, especially for extrapolation times exceeding 30 min.

The Gulf of Mexico Research Initiative: Managing a Multidisciplinary Data Explosion

NASA Astrophysics Data System (ADS)

Howard, M. K.; Gibeaut, J. C.; Reed, D.

2011-12-01

On April 20, 2010 the Deepwater Horizon drilling unit located in the northeastern Gulf of Mexico, experienced a catastrophic wellhead blowout. Roughly 5 billion barrels of oil and 1 million U.S. gallons of dispersant were released near the wellhead over the next three months. Within weeks of the blowout, BP announced the Gulf of Mexico Research Initiative (GRI) and pledged 50M/yr over 10 years for independent scientific research on the spill's impact on the ecosystem. Two months after the blowout three institutions were awarded a total of 25M in fast-track grants (Louisiana State University, Northern Gulf Institute, and Florida Institute of Oceanography). Soon after the Alabama Marine Environmental Sciences Consortium and the National Institutes of Health were awarded 5M and 10M, respectively. These five institutions began to generate data almost immediately. First year grants funded 100's of researchers from nearly 100 research units. Their activities included numerical modeling, field data collection, and laboratory experiments. Measured parameters included those associated with chemical analyses of oil, gas, and dispersants, studies of bacteria, plants and animals -from phytoplankton to marsh grasses, from zooplankton to cetaceans. Studies were conducted from estuaries to the deep Gulf, from atmosphere to sediments. Parameters from physical oceanography, marine meteorology, and biogeochemistry were measured in abundance. Additionally, impact studies on human mental, physical health and businesses were made. Proposals for years 2-4 of the program were to be awarded in August 2011 supporting 4-8 research consortia. Consortia may have up to 20 named researchers. In aggregate, these studies yielded a multidisciplinary data explosion. Following the fast-track awards the GRI Administrative Unit (AU) was established and a data management activity initiated. That activity became the GRI Information and Data Cooperative (GRIIDC). "Cooperative" emphasizes the collaborative relationship GRIIDC needed with the data originators. GRI founders only required that the AU provide a research database and data be shared openly with a minimum of delay and archived at national repositories. GRIIDC has three functions, to manage the data in cooperation with the originators, to facilitate public access to the data through the research database and to support management's need to track the project's progress. GRIIDC needed to rapidly assess the volume of data and specific parameters being collected, to quickly hire information technology and subject matter experts, to establish data policies for reporting, metadata content, submittal form and formats, and to establish and maintain mutually agreeable divisions of labor with the data originators. This presentation will describe the challenges and lessons learned by GRIIDC while building a collaborative end-to-end data management system designed to absorb, organize, share, and curate the massively heterogeneous data set produced by nearly $200M of GRI research.

The Influence of Academic Tracking on Adolescent Social Networks

ERIC Educational Resources Information Center

Fisher, Kim W.; Shogren, Karrie A.

2016-01-01

This study examined adolescents' social capital, through social network analyses (i.e., ego network analyses), in two high schools where students were placed into academic tracks adopted by the schools and shaped by disability status (i.e., general education, co-taught, segregated special education classrooms). The impact of academic tracks, as…

Characterization of single α-tracks by photoresist detection and AFM analysis-focus on biomedical science and technology

NASA Astrophysics Data System (ADS)

Falzone, Nadia; Myhra, Sverre; Chakalova, Radka; Hill, Mark A.; Thomson, James; Vallis, Katherine A.

2013-11-01

The interactions between energetic ions and biological and/or organic target materials have recently attracted theoretical and experimental attention, due to their implications for detector and device technologies, and for therapeutic applications. Most of the attention has focused on detection of the primary ionization tracks, and their effects, while recoil target atom tracks remain largely unexplored. Detection of tracks by a negative tone photoresist (SU-8), followed by standard development, in combination with analysis by atomic force microscopy, shows that both primary and recoil tracks are revealed as conical spikes, and can be characterized at high spatial resolution. The methodology has the potential to provide detailed information about single impact events, which may lead to more effective and informative detector technologies and advanced therapeutic procedures. In comparison with current characterization methods the advantageous features include: greater spatial resolution by an order of magnitude (20 nm) detection of single primary and associated recoil tracks; increased range of fluence (to 2.5 × 109 cm-2) sensitivity to impacts at grazing angle incidence; and better definition of the lateral interaction volume in target materials.

Impact of different climatic flows on typhoon tracks

NASA Astrophysics Data System (ADS)

Qian, Wei-hong; Huang, Jing

2018-04-01

A tropical cyclone (TC) vortex is considered to be embedded in and steered by a large-scale environmental flow. The environmental flow can be decomposed into two parts: temporal climatic flow and anomaly. The former is defined according to the calendar climatology with a diurnal cycle and a seasonal cycle. Thus, the temporal climatic flow of the atmosphere, which can be estimated using reanalysis data, varies with regions, altitudes, and hours. The impact of different climatic flows on TC tracks in the Northwest Pacific is examined using a simple generalized beta-advection model. Results show that the predicted tracks of two TC cases have large deviations from their best tracks in the following 1-2 days if the temporal climatic wind is replaced by other hourly climatic winds on the same calendar day or by a several-day-mean climatic wind. The track deviation is more significant when the climatic wind difference is larger than 2 m s-1. This experiment reconfirms that a TC track is influenced by temporal climatic flow and interaction with other disturbances in the vicinity.

Assessing the capability of high resolution climatic model experiments to simulate Mediterranean cyclonic tracks

NASA Astrophysics Data System (ADS)

Hatzaki, M.; Flocas, H. A.; Giannakopoulos, C.; Kostopoulou, E.; Kouroutzoglou, I.; Keay, K.; Simmonds, I.

2010-09-01

In this study, a comparison of a reanalysis driven simulation to a GCM driven simulation of a regional climate model is performed in order to assess the model's ability to capture the climatic characteristics of cyclonic tracks in the Mediterranean in the present climate. The ultimate scope of the study will be to perform a future climate projection related to cyclonic tracks in order to better understand and assess climate change in the Mediterranean. The climatology of the cyclonic tracks includes inter-monthly variations, classification of tracks according to their origin domain, dynamic and kinematic characteristics, as well as trend analysis. For this purpose, the ENEA model is employed based on PROTHEUS system composed of the RegCM atmospheric regional model and the MITgcm ocean model, coupled through the OASIS3 flux coupler. These model data became available through the EU Project CIRCE which aims to perform, for the first time, climate change projections with a realistic representation of the Mediterranean Sea. Two experiments are employed; a) the ERA402 with lateral Boundary conditions from ERA40 for the 43-year period 1958-2000, and b) the EH5OM_20C3M where the lateral boundary conditions for the atmosphere (1951-2000) are taken from the ECHAM5-MPIOM 20c3m global simulation (run3) included in the IPCC-AR4. The identification and tracking of cyclones is performed with the aid of the Melbourne University algorithm (MS algorithm), according to the Lagrangian perspective. MS algorithm characterizes a cyclone only if a vorticity maximum could be connected with a local pressure minimum. This approach is considered to be crucial, since open lows are also incorporated into the storm life-cycle, preventing possible inappropriate time series breaks, if a temporary weakening to an open-low state occurs. The model experiments verify that considerable inter-monthly variations of track density occur in the Mediterranean region, consistent with previous studies. The classification of the tracks according to their origin domain show that the vast majority originate within the examined area itself. The study of the kinematic and dynamic parameters of tracks according to their origin demonstrate that deeper cyclones follow the SW track. ACKNOWLEDGMENTS: M. Hatzaki would like to thank the Greek State Scholarships Foundation for financial support through the program of postdoctoral research. The support of EU-FP6 project CIRCE Integrated Project-Climate Change and Impact Research: the Mediterranean Environment (http://www.circeproject.eu) for climate model data provision is also greatly acknowledged.

Load environment of rail joint bars - phase I, effects of track parameters on rail joint stresses and crack growth.

DOT National Transportation Integrated Search

2013-04-01

The load environment of joint bars was assessed under a variety of loading and track conditions. Bending stresses, thermal stresses, and residual stresses were measured on commonly used joint bars. Crack growth rates from artificially induced cracks ...

Impact, Spreading and Splashing of Superfluid Drops

NASA Astrophysics Data System (ADS)

Taborek, Peter; Wallace, Mattew; Mallin, David; Aguirre, Andres; Langley, Kenneth; Thoroddsen, Sigurdur

2017-11-01

We investigate the impact of superfluid and normal liquid helium drops onto glass plates, in a custom-made optical cryostat, over a temperature range from 1.3 - 5 K. The unusual properties of liquid helium allow us to explore ranges of parameters that are difficult to obtain in conventional systems. Even in the normal state with T >2.17K, the viscosity and surface tension of liquid helium are unusually low, so it is easy to prepare drops with Re >30,000 and We >500. We track the spreading radius of the fluid rim, which initially grows as a power law in time with an exponent of 0.5 , while transitioning to Tanner's law at later times. In the superfluid state the rim velocity can exceed 4 m/s, which is significantly higher than the superfluid critical velocity. Here we see no splashing even at Re >100,000. Our experiments take place in an atmosphere of helium gas. In conventional impact splashing the exterior air is incondensable, while our impacts in helium involve a condensable exterior phase, so the dynamics can be expected to be quite different. We study how these differences affect the splashing.

Postural stabilizing effect of alfacalcidol and active absorbable algal calcium (AAA Ca) compared with calcium carbonate assessed by computerized posturography.

PubMed

Fujita, Takuo; Nakamura, Shoji; Ohue, Mutsumi; Fujii, Yoshio; Miyauchi, Akimitsu; Takagi, Yasuyuki; Tsugeno, Hirofumi

2007-01-01

Sway and postural instability have drawn attention as a risk factor for osteoporotic fracture, in addition to low bone mineral density (BMD) and poor bone quality. In view of the fracture-reducing effect of alfacalcidol and active absorbable algal calcium (AAA Ca) not readily explained by rather mild increases of BMD, attempts were made to evaluate postural stabilizing effect of alfacalcidol, AAA Ca, and calcium carbonate (CaCO(3)) by computerized posturography. Track of the gravity center was analyzed to calculate parameters related to tract length, track range, and track density to express the degree of sway before and after supplementation in 126 subjects ranging in age between 20 and 81 years randomly divided into four groups. Supplementation with AAA Ca containing 900 mg elemental Ca (group A), no calcium (group B), CaCO(3) also containing 900 mg elemental Ca (group C), or alfacalcidol (group D) continued daily for 12 months. For each parameter, the ratio closed eye value/open eye value (Romberg ratio) was calculated to detect aggravation of sway by eye closure. Age, parameters of Ca and P, and proportions of subjects with fracture and those with low BMD showed no marked deviation among the groups. With eyes open, significant decreases of a track range parameter (REC) from group B was noted in groups A (P = 0.0397) and D (P = 0.0296), but not in group C according to multiple comparison by Scheffe, indicating superior postural stabilizing effect of A and D over C. In the first 2 months, a significant fall was already evident in REC from group B in group D (P = 0.0120) with eyes open. Paired comparison of sway parameters before and after supplementation revealed a significant increase of track density parameter (LNGA), indicating sway control efficiency and a significant decrease of REC in groups A and D compared to group B with eyes open. With eyes closed, only group A showed a significant improvement from group B (P = 0.0456; Fig. 1), with a significant shortening on paired After/Before comparison (P = 0.0142; Fig. 2). Computerized posturography appears to be useful in analyzing sway phenomena especially as to the effects of vitamin D and various Ca preparations.

Tracking Electroencephalographic Changes Using Distributions of Linear Models: Application to Propofol-Based Depth of Anesthesia Monitoring.

PubMed

Kuhlmann, Levin; Manton, Jonathan H; Heyse, Bjorn; Vereecke, Hugo E M; Lipping, Tarmo; Struys, Michel M R F; Liley, David T J

2017-04-01

Tracking brain states with electrophysiological measurements often relies on short-term averages of extracted features and this may not adequately capture the variability of brain dynamics. The objective is to assess the hypotheses that this can be overcome by tracking distributions of linear models using anesthesia data, and that anesthetic brain state tracking performance of linear models is comparable to that of a high performing depth of anesthesia monitoring feature. Individuals' brain states are classified by comparing the distribution of linear (auto-regressive moving average-ARMA) model parameters estimated from electroencephalographic (EEG) data obtained with a sliding window to distributions of linear model parameters for each brain state. The method is applied to frontal EEG data from 15 subjects undergoing propofol anesthesia and classified by the observers assessment of alertness/sedation (OAA/S) scale. Classification of the OAA/S score was performed using distributions of either ARMA parameters or the benchmark feature, Higuchi fractal dimension. The highest average testing sensitivity of 59% (chance sensitivity: 17%) was found for ARMA (2,1) models and Higuchi fractal dimension achieved 52%, however, no statistical difference was observed. For the same ARMA case, there was no statistical difference if medians are used instead of distributions (sensitivity: 56%). The model-based distribution approach is not necessarily more effective than a median/short-term average approach, however, it performs well compared with a distribution approach based on a high performing anesthesia monitoring measure. These techniques hold potential for anesthesia monitoring and may be generally applicable for tracking brain states.

Impact of Preferred Eddy Tracks on Transport and Mixing in the Eastern South Pacific

NASA Astrophysics Data System (ADS)

Belmadani, A.; Donoso, D.; Auger, P. A.; Chaigneau, A.

2017-12-01

Mesoscale eddies, which play a fundamental role in the transport of mass, heat, nutrients, and biota across the oceans, have been suggested to propagate preferently along specific tracks. These preferred pathways, also called eddy trains, are near-zonal due to westward drift of individual vortices, and tend to be polarized (ie alternatively dominated by anticyclonic/cyclonic eddies), coinciding with the recently discovered latent striations (quasi-zonal mesoscale jet-like features). While significant effort has been made to understand the dynamics of striations and their interplay with mesoscale eddies, the impact of repeated eddy tracks on physical (temperature, salinity), biogeochemical (oxygen, carbon, nutrients) and other tracers (e.g. chlorophyll, marine debris) has received little attention. Here we report on the results of numerical modeling experiments that simulate the impact of preferred eddy tracks on the transport and mixing of water particles in the Eastern South Pacific off Chile. A 30-year interannual simulation of the oceanic circulation in this region has been performed over 1984-2013 with the ROMS (Regional Oceanic Modeling System) at an eddy-resolving resolution (10 km). Objective tracking of mesoscale coherent vortices is obtained using automated methods, allowing to compute the contribution of eddies to the ocean circulation. Preferred eddy tracks are further isolated from the more random eddies, by comparing the distances between individual tracks and the striated pattern in long-term mean eddy polarity with a least-squares approach. The remaining non-eddying flow may also be decomposed into time-mean and anomalous circulation, and/or small- and large-scale circulation. Neutrally-buoyant Lagrangian floats are then released uniformly into the various flow components as well as the total flow, and tracked forward in time with the ARIANE software. The dispersion patterns of water particles are used to estimate the respective contributions of organized and random eddies, mean flow, large-scale perturbations etc. to mixing properties and transport pathways. Float release into the full flow inside selected vortices is also used to document the impact of eddy trains on the transformation of water masses inferred from changes in temperature/salinity along float trajectories.

Response of winter North Atlantic storm track to climate change in the CNRM-CM5 simulations

NASA Astrophysics Data System (ADS)

Chauvin, Fabrice; Oudar, Thomas; Sanchez-Gomez, Emilia; Terray, Laurent

2016-04-01

Climate variability in Europe in winter is largely controlled by North Atlantic storm tracks. These are associated with transport of energy, momentum, and water vapour, between the equator and mid latitudes. Extratropical cyclones have caused severe damages over some regions in north-western Europe, since they can combine extreme precipitation and strong winds. This is why it is relevant to study the impact of climate change on the extratropical cyclones, principally on their intensity, position or lifespan. Indeed, several recent studies have focused on this subject by using atmospheric reanalysis and general circulation models (GCMs). The main conclusions from the CMIP3 simulations showed a decreasing of the total number of cyclones and a poleward shift of their tracks in response to global warming. In the recent CMIP5 exercise, the consensus is not so clear, probably due to more complex feedbacks acting in the different models. Thus, the question of changes in North Atlantic storm-tracks with warming remains open. The main goal of this work is to explore the changes in the North Atlantic storm-tracks in the past and future decades and to analyze the contributions of the different external forcings (natural and anthropogenic) versus the internal variability. On this purpose, we use the Detection and Attribution (D&A) simulations performed with the coupled model CNRM-CM5. To characterize the extratropical cyclones and their tracks, a tracking scheme based on the detection of maximum of relative vorticity at 850 hPa is conducted. We show that the coupled model fairly well reproduces the storm genesis locations as well as the tracks pathways comparing to several atmospheric reanalysis products. In the recent historical period (1950-2005), the model shows a decrease in the number of storms in the southern North-Atlantic, when all the forcings (anthropogenic and natural) are prescribed. Even if the role of internal variability is important in the last decades (the inter-members spread is very large), and the signals rarely emerge from the noise, analysis based on the Eady Growth Rate parameter has lead to quantify the respective roles of baroclinicity and meridional temperature gradients. Finally, in the scenario (RCP8.5), the tendency seen in the all-forcings historical run is confirmed and reinforced.

Efficient model for low-energy transverse beam dynamics in a nine-cell 1.3 GHz cavity

NASA Astrophysics Data System (ADS)

Hellert, Thorsten; Dohlus, Martin; Decking, Winfried

2017-10-01

FLASH and the European XFEL are SASE-FEL user facilities, at which superconducting TESLA cavities are operated in a pulsed mode to accelerate long bunch-trains. Several cavities are powered by one klystron. While the low-level rf system is able to stabilize the vector sum of the accelerating gradient of one rf station sufficiently, the rf parameters of individual cavities vary within the bunch-train. In correlation with misalignments, intrabunch-train trajectory variations are induced. An efficient model is developed to describe the effect at low beam energy, using numerically adjusted transfer matrices and discrete coupler kick coefficients, respectively. Comparison with start-to-end tracking and dedicated experiments at the FLASH injector will be shown. The short computation time of the derived model allows for comprehensive numerical studies on the impact of misalignments and variable rf parameters on the transverse intra-bunch-train beam stability at the injector module. Results from both, statistical multibunch performance studies and the deduction of misalignments from multibunch experiments are presented.

EDDIX--a database of ionisation double differential cross sections.

PubMed

MacGibbon, J H; Emerson, S; Liamsuwan, T; Nikjoo, H

2011-02-01

The use of Monte Carlo track structure is a choice method in biophysical modelling and calculations. To precisely model 3D and 4D tracks, the cross section for the ionisation by an incoming ion, double differential in the outgoing electron energy and angle, is required. However, the double differential cross section cannot be theoretically modelled over the full range of parameters. To address this issue, a database of all available experimental data has been constructed. Currently, the database of Experimental Double Differential Ionisation Cross sections (EDDIX) contains over 1200 digitalised experimentally measured datasets from the 1960s to present date, covering all available ion species (hydrogen to uranium) and all available target species. Double differential cross sections are also presented with the aid of an eight parameter functions fitted to the cross sections. The parameters include projectile species and charge, target nuclear charge and atomic mass, projectile atomic mass and energy, electron energy and deflection angle. It is planned to freely distribute EDDIX and make it available to the radiation research community for use in the analytical and numerical modelling of track structure.

Accurate motion parameter estimation for colonoscopy tracking using a regression method

NASA Astrophysics Data System (ADS)

Liu, Jianfei; Subramanian, Kalpathi R.; Yoo, Terry S.

2010-03-01

Co-located optical and virtual colonoscopy images have the potential to provide important clinical information during routine colonoscopy procedures. In our earlier work, we presented an optical flow based algorithm to compute egomotion from live colonoscopy video, permitting navigation and visualization of the corresponding patient anatomy. In the original algorithm, motion parameters were estimated using the traditional Least Sum of squares(LS) procedure which can be unstable in the context of optical flow vectors with large errors. In the improved algorithm, we use the Least Median of Squares (LMS) method, a robust regression method for motion parameter estimation. Using the LMS method, we iteratively analyze and converge toward the main distribution of the flow vectors, while disregarding outliers. We show through three experiments the improvement in tracking results obtained using the LMS method, in comparison to the LS estimator. The first experiment demonstrates better spatial accuracy in positioning the virtual camera in the sigmoid colon. The second and third experiments demonstrate the robustness of this estimator, resulting in longer tracked sequences: from 300 to 1310 in the ascending colon, and 410 to 1316 in the transverse colon.

Profile parameters of wheelset detection for high speed freight train

NASA Astrophysics Data System (ADS)

Yang, Kai; Ma, Li; Gao, Xiaorong; Wang, Li

2012-04-01

Because of freight train, in China, transports goods on railway freight line throughout the country, it does not depart from or return to engine shed during a long phase, thus we cannot monitor the quality of wheel set effectively. This paper provides a system which uses leaser and high speed camera, applies no-contact light section technology to get precise wheel set profile parameters. The paper employs clamping-track method to avoid complex railway ballast modification project. And detailed descript an improved image-tracking algorithm to extract central line from profile curve. For getting one pixel width and continuous line of the profile curve, uses local gray maximum points as direction control points to direct tracking direction. The results based on practical experiment show the system adapted to detection environment of high speed and high vibration, and it can effectively detect the wheelset geometric parameters with high accuracy. The system fills the gaps in wheel set detection for freight train in main line and has an enlightening function on monitoring the quality of wheel set.

Logistic Mixed Models to Investigate Implicit and Explicit Belief Tracking

PubMed Central

Lages, Martin; Scheel, Anne

2016-01-01

We investigated the proposition of a two-systems Theory of Mind in adults’ belief tracking. A sample of N = 45 participants predicted the choice of one of two opponent players after observing several rounds in an animated card game. Three matches of this card game were played and initial gaze direction on target and subsequent choice predictions were recorded for each belief task and participant. We conducted logistic regressions with mixed effects on the binary data and developed Bayesian logistic mixed models to infer implicit and explicit mentalizing in true belief and false belief tasks. Although logistic regressions with mixed effects predicted the data well a Bayesian logistic mixed model with latent task- and subject-specific parameters gave a better account of the data. As expected explicit choice predictions suggested a clear understanding of true and false beliefs (TB/FB). Surprisingly, however, model parameters for initial gaze direction also indicated belief tracking. We discuss why task-specific parameters for initial gaze directions are different from choice predictions yet reflect second-order perspective taking. PMID:27853440

When and How Is Patella Tracking Best Assessed in Total Knee Arthroplasty Surgery?

PubMed

Westerman, Richard W; Bhangoo, Navjot S; James, Peter

2016-05-01

Much emphasis has been placed on the role of patella resurfacing in total knee arthroplasty (TKA), yet the impact of soft tissue balancing has frequently been understated. The authors used a novel system to precisely assess patellofemoral joint (PFJ) tracking intraoperatively, to determine the impact of both retinacular reconstruction and tourniquet use on PFJ kinematics. PFJ kinematics assessed intraoperatively for 20 consecutive TKA patients. Measurements were recorded using both the "no thumb technique" and following reconstruction of the retinaculum with two positional sutures. The tourniquet was deflated and both measurements were repeated. Tourniquet inflation was not found to have a significant impact on the patella tracking (mean translation 0.9 mm, p = 0.15). Patella retinacular reconstruction generated a significant medialization of the patella by a mean of 5.5 mm (p < 0.0001) when compared with the traditional retinacular open "no thumb technique." The use of a tourniquet has been shown to have no effect on patella tracking. Reconstruction of the patella retinaculum markedly improves patella tracking, generating a mean medialization of 15%. The authors advocate the routine use of two positional sutures to restore the patella retinaculum, before trialing the patella component, as a reproducible means of assessing the PFJ kinematics. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Swift heavy ion irradiation of CaF2 - from grooves to hillocks in a single ion track

NASA Astrophysics Data System (ADS)

Gruber, Elisabeth; Salou, Pierre; Bergen, Lorenz; El Kharrazi, Mourad; Lattouf, Elie; Grygiel, Clara; Wang, Yuyu; Benyagoub, Abdenacer; Levavasseur, Delphine; Rangama, Jimmy; Lebius, Henning; Ban-d'Etat, Brigitte; Schleberger, Marika; Aumayr, Friedrich

2016-10-01

A novel form of ion-tracks, namely nanogrooves and hillocks, are observed on CaF2 after irradiation with xenon and lead ions of about 100 MeV kinetic energy. The irradiation is performed under grazing incidence (0.3°-3°) which forces the track to a region in close vicinity to the surface. Atomic force microscopy imaging of the impact sites with high spatial resolution reveals that the surface track consists in fact of three distinct parts: each swift heavy ion impacting on the CaF2 surface first opens a several 100 nm long groove bordered by a series of nanohillocks on both sides. The end of the groove is marked by a huge single hillock and the further penetration of the swift projectile into deeper layers of the target is accompanied by a single protrusion of several 100 nm in length slowly fading until the track vanishes. By comparing experimental data for various impact angles with results of a simulation, based on a three-dimensional version of the two-temperature-model (TTM), we are able to link the crater and hillock formation to sublimation and melting processes of CaF2 due to the local energy deposition by swift heavy ions.

Atmospheric Motion Vectors from INSAT-3D: Initial quality assessment and its impact on track forecast of cyclonic storm NANAUK

NASA Astrophysics Data System (ADS)

Deb, S. K.; Kishtawal, C. M.; Kumar, Prashant; Kiran Kumar, A. S.; Pal, P. K.; Kaushik, Nitesh; Sangar, Ghansham

2016-03-01

The advanced Indian meteorological geostationary satellite INSAT-3D was launched on 26 July 2013 with an improved imager and an infrared sounder and is placed at 82°E over the Indian Ocean region. With the advancement in retrieval techniques of different atmospheric parameters and with improved imager data have enhanced the scope for better understanding of the different tropical atmospheric processes over this region. The retrieval techniques and accuracy of one such parameter, Atmospheric Motion Vectors (AMV) has improved significantly with the availability of improved spatial resolution data along with more options of spectral channels in the INSAT-3D imager. The present work is mainly focused on providing brief descriptions of INSAT-3D data and AMV derivation processes using these data. It also discussed the initial quality assessment of INSAT-3D AMVs for a period of six months starting from 01 February 2014 to 31 July 2014 with other independent observations: i) Meteosat-7 AMVs available over this region, ii) in-situ radiosonde wind measurements, iii) cloud tracked winds from Multi-angle Imaging Spectro-Radiometer (MISR) and iv) numerical model analysis. It is observed from this study that the qualities of newly derived INSAT-3D AMVs are comparable with existing two versions of Meteosat-7 AMVs over this region. To demonstrate its initial application, INSAT-3D AMVs are assimilated in the Weather Research and Forecasting (WRF) model and it is found that the assimilation of newly derived AMVs has helped in reduction of track forecast errors of the recent cyclonic storm NANAUK over the Arabian Sea. Though, the present study is limited to its application to one case study, however, it will provide some guidance to the operational agencies for implementation of this new AMV dataset for future applications in the Numerical Weather Prediction (NWP) over the south Asia region.

Wheel-Sleeper Impact Model in Rail Vehicles Analysis

NASA Astrophysics Data System (ADS)

Brabie, Dan

The current paper establishes the necessary prerequisites for studying post-derailment dynamic behavior of high-speed rail vehicles by means of multi-body system (MBS) software. A finite-element (FE) model of one rail vehicle wheel impacting a limited concrete sleeper volume is built in LS-DYNA. A novel simulation scheme is employed for obtaining the necessary wheel-sleeper impact data, transferred to the MBS code as pre-defined look-up tables of the wheel's impulse variation during impact. The FE model is tentatively validated successfully by comparing the indentation marks with one photograph from an authentic derailment for a continuous impact sequence over three subsequent sleepers. A post-derailment module is developed and implemented in the MBS simulation tool GENSYS, which detects the wheel contact with sleepers and applies valid longitudinal, lateral and vertical force resultants based on the existing impact conditions. The accuracy of the MBS code in terms of the wheels three-dimensional trajectory over 24 consecutive sleepers is successfully compared with its FE counterpart for an arbitrary impact scenario. An axle mounted brake disc is tested as an alternative substitute guidance mechanism after flange climbing derailments at 100 and 200 km/h on the Swedish high-speed tilting train X 2000. Certain combinations of brake disc geometrical parameters manage to stop the lateral deviation of the wheelsets in circular curve sections at high lateral track plane acceleration.

Addressing chronic operational issues at the W. M. Keck Observatory

NASA Astrophysics Data System (ADS)

Nordin, Tom; Matsuda, Richard

2016-07-01

The W. M. Keck Observatory (WMKO) has a good track record at addressing large critical faults which impact observing. Our performance tracking and correcting chronic minor faults has been mixed, yet this class of problems has a significant negative impact on scientific productivity and staff effectiveness. We have taken steps to address this shortcoming. This paper outlines the creation of a program to identify, categorize and rank these chronic operational issues, track them over time, and develop management options for their resolution. The success of the program at identifying these chronic operational issues and the advantages of dedicating observatory resources to this endeavor are presented.

Tracking and data relay satellite system configuration and tradeoff study. Volume 5: User impact and ground station design, part 1

NASA Technical Reports Server (NTRS)

Hill, T. E.

1972-01-01

The configuration of the user transponder on the Tracking and Data Relay satellite is described. The subjects discussed are: (1) transponder concepts and trades, (2) ground station design, (3) antenna configurations for ground equipment, (4) telemetry facilities, (5) signal categories, and (6) satellite tracking.

Using the Image Analysis Method for Describing Soil Detachment by a Single Water Drop Impact

PubMed Central

Ryżak, Magdalena; Bieganowski, Andrzej

2012-01-01

The aim of the present work was to develop a method based on image analysis for describing soil detachment caused by the impact of a single water drop. The method consisted of recording tracks made by splashed particles on blotting paper under an optical microscope. The analysis facilitated division of the recorded particle tracks on the paper into drops, “comets” and single particles. Additionally, the following relationships were determined: (i) the distances of splash; (ii) the surface areas of splash tracks into relation to distance; (iii) the surface areas of the solid phase transported over a given distance; and (iv) the ratio of the solid phase to the splash track area in relation to distance. Furthermore, the proposed method allowed estimation of the weight of soil transported by a single water drop splash in relation to the distance of the water drop impact. It was concluded that the method of image analysis of splashed particles facilitated analysing the results at very low water drop energy and generated by single water drops.

Impact of a workplace physical activity tracking program on biometric health outcomes.

PubMed

Yu, Jiani; Abraham, Jean M; Dowd, Bryan; Higuera, Lucas F; Nyman, John A

2017-12-01

Wellness programs are a popular strategy utilized by large U.S. employers. As mobile health applications and wearable tracking devices increase in prevalence, many employers now offer physical activity tracking applications. This longitudinal study evaluates the impact of engagement with a web-based, physical activity tracking program on changes in individuals' biometric outcomes in an employer population. The study population includes active employees and adult dependents continuously enrolled in an eligible health plan and who have completed at least two biometric screenings (n=36,882 person-years with 11,436 unique persons) between 2011 and 2014. Using difference-in-differences (DID) regression, we estimate the effect of participation in the physical activity tracking application on BMI, total cholesterol, and blood pressure. Participation was significantly associated with a reduction of 0.275 in BMI in the post-period, relative to the comparison group, representing a 1% change from baseline BMI. The program did not have a statistically significant impact on cholesterol or blood pressure. Sensitivity checks revealed slightly larger BMI reductions among participants with higher intensity of tracking activity and in the period following the employer's shift to an outcomes-based incentive design. Results are broadly consistent with the existing literature on changes in biometric outcomes from workplace initiatives promoting increased physical activity. Employers should have modest expectations about the potential health benefits of such programs, given current designs and implementation in real-world settings. Copyright © 2017 Elsevier Inc. All rights reserved.

Enhanced robust fractional order proportional-plus-integral controller based on neural network for velocity control of permanent magnet synchronous motor.

PubMed

Zhang, Bitao; Pi, YouGuo

2013-07-01

The traditional integer order proportional-integral-differential (IO-PID) controller is sensitive to the parameter variation or/and external load disturbance of permanent magnet synchronous motor (PMSM). And the fractional order proportional-integral-differential (FO-PID) control scheme based on robustness tuning method is proposed to enhance the robustness. But the robustness focuses on the open-loop gain variation of controlled plant. In this paper, an enhanced robust fractional order proportional-plus-integral (ERFOPI) controller based on neural network is proposed. The control law of the ERFOPI controller is acted on a fractional order implement function (FOIF) of tracking error but not tracking error directly, which, according to theory analysis, can enhance the robust performance of system. Tuning rules and approaches, based on phase margin, crossover frequency specification and robustness rejecting gain variation, are introduced to obtain the parameters of ERFOPI controller. And the neural network algorithm is used to adjust the parameter of FOIF. Simulation and experimental results show that the method proposed in this paper not only achieve favorable tracking performance, but also is robust with regard to external load disturbance and parameter variation. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

The impact of glide phases on the trackability of hydrodynamic trails in harbour seals (Phoca vitulina).

PubMed

Wieskotten, S; Dehnhardt, G; Mauck, B; Miersch, L; Hanke, W

2010-11-01

The mystacial vibrissae of harbour seals (Phoca vitulina) constitute a highly sensitive hydrodynamic receptor system enabling the seals to detect and follow hydrodynamic trails. In the wild, hydrodynamic trails, as generated by swimming fish, consist of cyclic burst-and-glide phases, associated with various differences in the physical parameters of the trail. Here, we investigated the impact of glide phases on the trackability of differently aged hydrodynamic trails in a harbour seal. As fish are not easily trained to swim certain paths with predetermined burst-and-glide phases, the respective hydrodynamic trails were generated using a remote-controlled miniature submarine. Gliding phases in hydrodynamic trails had a negative impact on the trackability when trails were 15 s old. The seal lost the generated trails more often within the transition zones, when the submarine switched from a burst to a glide moving pattern. Hydrodynamic parameter analysis (particle image velocimetry) revealed that the smaller dimensions and faster decay of hydrodynamic trails generated by the gliding submarine are responsible for the impaired success of the seal tracking the gliding phase. Furthermore, the change of gross water flow generated by the submarine from a rearwards-directed stream in the burst phase to a water flow passively dragged behind the submarine during gliding might influence the ability of the seal to follow the trail as this might cause a weaker deflection of the vibrissae. The possible ecological implications of intermittent swimming behaviour in fish for piscivorous predators are discussed.

Sensitivity Analysis of Repeat Track Estimation Techniques for Detection of Elevation Change in Polar Ice Sheets

NASA Astrophysics Data System (ADS)

Harpold, R. E.; Urban, T. J.; Schutz, B. E.

2008-12-01

Interest in elevation change detection in the polar regions has increased recently due to concern over the potential sea level rise from the melting of the polar ice caps. Repeat track analysis can be used to estimate elevation change rate by fitting elevation data to model parameters. Several aspects of this method have been tested to improve the recovery of the model parameters. Elevation data from ICESat over Antarctica and Greenland from 2003-2007 are used to test several grid sizes and types, such as grids based on latitude and longitude and grids centered on the ICESat reference groundtrack. Different sets of parameters are estimated, some of which include seasonal terms or alternate types of slopes (linear, quadratic, etc.). In addition, the effects of including crossovers and other solution constraints are evaluated. Simulated data are used to infer potential errors due to unmodeled parameters.

An adaptive tracking observer for failure-detection systems

NASA Technical Reports Server (NTRS)

Sidar, M.

1982-01-01

The design problem of adaptive observers applied to linear, constant and variable parameters, multi-input, multi-output systems, is considered. It is shown that, in order to keep the observer's (or Kalman filter) false-alarm rate (FAR) under a certain specified value, it is necessary to have an acceptable proper matching between the observer (or KF) model and the system parameters. An adaptive observer algorithm is introduced in order to maintain desired system-observer model matching, despite initial mismatching and/or system parameter variations. Only a properly designed adaptive observer is able to detect abrupt changes in the system (actuator, sensor failures, etc.) with adequate reliability and FAR. Conditions for convergence for the adaptive process were obtained, leading to a simple adaptive law (algorithm) with the possibility of an a priori choice of fixed adaptive gains. Simulation results show good tracking performance with small observer output errors and accurate and fast parameter identification, in both deterministic and stochastic cases.

Strain measurement of abdominal aortic aneurysm with real-time 3D ultrasound speckle tracking.

PubMed

Bihari, P; Shelke, A; Nwe, T H; Mularczyk, M; Nelson, K; Schmandra, T; Knez, P; Schmitz-Rixen, T

2013-04-01

Abdominal aortic aneurysm rupture is caused by mechanical vascular tissue failure. Although mechanical properties within the aneurysm vary, currently available ultrasound methods assess only one cross-sectional segment of the aorta. This study aims to establish real-time 3-dimensional (3D) speckle tracking ultrasound to explore local displacement and strain parameters of the whole abdominal aortic aneurysm. Validation was performed on a silicone aneurysm model, perfused in a pulsatile artificial circulatory system. Wall motion of the silicone model was measured simultaneously with a commercial real-time 3D speckle tracking ultrasound system and either with laser-scan micrometry or with video photogrammetry. After validation, 3D ultrasound data were collected from abdominal aortic aneurysms of five patients and displacement and strain parameters were analysed. Displacement parameters measured in vitro by 3D ultrasound and laser scan micrometer or video analysis were significantly correlated at pulse pressures between 40 and 80 mmHg. Strong local differences in displacement and strain were identified within the aortic aneurysms of patients. Local wall strain of the whole abdominal aortic aneurysm can be analysed in vivo with real-time 3D ultrasound speckle tracking imaging, offering the prospect of individual non-invasive rupture risk analysis of abdominal aortic aneurysms. Copyright © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Feasibility of two-dimensional speckle tracking in evaluation of arterial stiffness: Comparison with pulse wave velocity and conventional sonographic markers of atherosclerosis.

PubMed

Podgórski, Michał; Grzelak, Piotr; Kaczmarska, Magdalena; Polguj, Michał; Łukaszewski, Maciej; Stefańczyk, Ludomir

2018-02-01

Objective Arterial stiffening is an early marker of atherosclerosis that has a prognostic value for cardiovascular morbidity and mortality. Although many markers of arterial hardening have been proposed, the search is on for newer, more user-friendly and reliable surrogates. One such potential candidate has emerged from cardiology, the speckle-tracking technique. The aim of this study was to evaluate the feasibility of the two-dimensional speckle tracking for the evaluation of arterial wall stiffness in comparison with standard stiffness parameters. Methods Carotid ultrasound and applanation tonometry were performed in 188 patients with no cardiovascular risk factors. The following parameters were then evaluated: the intima-media complex thickness, distensibility coefficient, β-stiffness index, circumferential strain/strain rate, and pulse wave velocity and augmentation index. These variables were compared with each other and with patient age, and their reliability was assessed with Bland-Altman plots. Results Strain parameters derived from two-dimensional speckle tracking and intima-media complex thickness correlated better with age and pulse wave velocity than standard makers of arterial stiffness. Moreover, the reliability of these measurements was significantly higher than conventional surrogates. Conclusions Two-dimensional speckle tracing is a reliable method for the evaluation of arterial stiffness. Therefore, together with intima-media complex thickness measurement, it offers great potential in clinical practice as an early marker of atherosclerosis.

Real-time measurement system for tracking birefringence, weight, thickness, and surface temperature during drying of solution cast coatings and films

NASA Astrophysics Data System (ADS)

Unsal, E.; Drum, J.; Yucel, O.; Nugay, I. I.; Yalcin, B.; Cakmak, M.

2012-02-01

This paper describes the design and performance of a new instrument to track temporal changes in physical parameters during the drying behavior of solutions, as well as curing of monomers. This real-time instrument follows in-plane and out-of-plane birefringence, weight, thickness, and surface temperature during the course of solidification of coatings and films through solvent evaporation and thermal or photocuring in a controlled atmosphere. It is specifically designed to simulate behavior of polymer solutions inside an industrial size, continuous roll-to-roll solution casting line and other coating operations where resins are subjected to ultraviolet (UV) curing from monomer precursors. Controlled processing parameters include air speed, temperature, initial cast thickness, and solute concentration, while measured parameters are thickness, weight, film temperature, in-plane and out-of-plane birefringence. In this paper, we illustrate the utility of this instrument with solution cast and dried poly (amide-imide)/DMAc (Dimethylacetamide) solution, water based black paint, and organo-modified clay/NMP (N-Methylpyrrolidone) solution. In addition, the physical changes that take place during UV photo polymerization of a monomer are tracked. This instrument is designed to be generic and it can be used for tracking any drying/swelling/solidification systems including paper, foodstuffs such as; grains, milk as well as pharmaceutical thin paste and slurries.

School-to-Work Transition of College Graduates in Korea: The Impact of High School Track on College Performance and Post-College Occupational Outcomes

ERIC Educational Resources Information Center

Kwon, Sung Youn

2014-01-01

This study aimed at examining the impacts of high school track on college performance and subsequent occupational outcomes after college graduation. To this end, the Korean Education and Employment Panel (KEEP) data from 2004 through 2010, including 4,000 samples of 12th graders as of 2004 from vocational and general high schools, were analyzed.…

Triply redundant integrated navigation and asset visibility system

DOEpatents

Smith, Stephen F [Loudon, TN; Moore, James A [Powell, TN

2011-11-29

Methods and apparatus are described for a navigation system. A method includes providing a global positioning system fix having a plurality of tracking parameters; providing a theater positioning system fix; monitoring the plurality of tracking parameters for predetermined conditions; and, when the predetermined conditions are met, sending a notifying signal and switching to the theater positioning system fix as a primary fix. An apparatus includes a system controller; a global positioning system receiver coupled to the system controller; a radio frequency locating receiver coupled to the system controller; and an operator interface coupled to the system controller.

Triply redundant integrated navigation and asset visibility system

DOEpatents

Smith, Stephen F.; Moore, James A.

2013-01-22

Methods and apparatus are described for a navigation system. A method includes providing a global positioning system fix having a plurality of tracking parameters; providing a theater positioning system fix; monitoring the plurality of tracking parameters for predetermined conditions; and, when the predetermined conditions are met, sending a notifying signal and switching to the theater positioning system fix as a primary fix. An apparatus includes a system controller; a global positioning system receiver coupled to the system controller; a radio frequency locating receiver coupled to the system controller; and an operator interface coupled to the system controller.

Finite-time tracking control for multiple non-holonomic mobile robots based on visual servoing

NASA Astrophysics Data System (ADS)

Ou, Meiying; Li, Shihua; Wang, Chaoli

2013-12-01

This paper investigates finite-time tracking control problem of multiple non-holonomic mobile robots via visual servoing. It is assumed that the pinhole camera is fixed to the ceiling, and camera parameters are unknown. The desired reference trajectory is represented by a virtual leader whose states are available to only a subset of the followers, and the followers have only interaction. First, the camera-objective visual kinematic model is introduced by utilising the pinhole camera model for each mobile robot. Second, a unified tracking error system between camera-objective visual servoing model and desired reference trajectory is introduced. Third, based on the neighbour rule and by using finite-time control method, continuous distributed cooperative finite-time tracking control laws are designed for each mobile robot with unknown camera parameters, where the communication topology among the multiple mobile robots is assumed to be a directed graph. Rigorous proof shows that the group of mobile robots converges to the desired reference trajectory in finite time. Simulation example illustrates the effectiveness of our method.

Method and apparatus for optimizing a train trip using signal information

DOEpatents

Kumar, Ajith Kuttannair; Daum, Wolfgang; Otsubo, Tom; Hershey, John Erik; Hess, Gerald James

2013-02-05

One embodiment of the invention includes a system for operating a railway network comprising a first railway vehicle (400) during a trip along track segments (401/412/420). The system comprises a first element (65) for determining travel parameters of the first railway vehicle (400), a second element (65) for determining travel parameters of a second railway vehicle (418) relative to the track segments to be traversed by the first vehicle during the trip, a processor (62) for receiving information from the first (65) and the second (65) elements and for determining a relationship between occupation of a track segment (401/412/420) by the second vehicle (418) and later occupation of the same track segment by the first vehicle (400) and an algorithm embodied within the processor (62) having access to the information to create a trip plan that determines a speed trajectory for the first vehicle (400), wherein the speed trajectory is responsive to the relationship and further in accordance with one or more operational criteria for the first vehicle (400).

Computer-Aided Design and Manufacturing for Closed-Die Forging of Track Shoes and Links

DTIC Science & Technology

1976-07-01

file. VII-39 CALL RESTRI(TAG) Restores a blanked item. CALL SCROLG( NLINES ,IYTOP) To adjust scroller parameters. Graphics Monitor must be in use... NLINES : Number of lines to be displayed. IYTOP: Y-coordinate of the top line. Each line is 25 units vertical. CALL TRACK To enable the tracking...5. NLINES - The number of lines reserved for the text scroller area when text is displayed along with graphic images. 6. AL - The vertical

Charged particle tracking without magnetic field: Optimal measurement of track momentum by a Bayesian analysis of the multiple measurements of deflections due to multiple scattering

NASA Astrophysics Data System (ADS)

Frosini, Mikael; Bernard, Denis

2017-09-01

We revisit the precision of the measurement of track parameters (position, angle) with optimal methods in the presence of detector resolution, multiple scattering and zero magnetic field. We then obtain an optimal estimator of the track momentum by a Bayesian analysis of the filtering innovations of a series of Kalman filters applied to the track. This work could pave the way to the development of autonomous high-performance gas time-projection chambers (TPC) or silicon wafer γ-ray space telescopes and be a powerful guide in the optimization of the design of the multi-kilo-ton liquid argon TPCs that are under development for neutrino studies.

Joint polarization tracking and channel equalization based on radius-directed linear Kalman filter

NASA Astrophysics Data System (ADS)

Zhang, Qun; Yang, Yanfu; Zhong, Kangping; Liu, Jie; Wu, Xiong; Yao, Yong

2018-01-01

We propose a joint polarization tracking and channel equalization scheme based on radius-directed linear Kalman filter (RD-LKF) by introducing the butterfly finite-impulse-response (FIR) filter in our previously proposed RD-LKF method. Along with the fast polarization tracking, it can also simultaneously compensate the inter-symbol interference (ISI) effects including residual chromatic dispersion and polarization mode dispersion. Compared with the conventional radius-directed equalizer (RDE) algorithm, it is demonstrated experimentally that three times faster convergence speed, one order of magnitude better tracking capability, and better BER performance is obtained in polarization division multiplexing 16 quadrature amplitude modulation system. Besides, the influences of the algorithm parameters on the convergence and the tracking performance are investigated by numerical simulation.

Changes of Mediterranean cyclones in the future climate employing high resolution climate simulations

NASA Astrophysics Data System (ADS)

Hatzaki, M.; Flocas, H. A.; Kouroutzoglou, J.; Keay, K.; Simmonds, I.; Giannakopoulos, C. A.; Brikolas, V.

2011-12-01

A number of studies suggest that cyclone activity over both hemispheres has changed over the second half of the 20th century. The assessment of the future changes of the cyclonic activity as imposed by global warming conditions is very important since these cyclones can be associated with extreme precipitation conditions, severe storms and floods. This is more important for the Mediterranean that has been found to be more vulnerable to climate change. The main objective of the current study is to better understand and assess future changes in the main characteristics of Mediterranean cyclones, including temporal and spatial variations of frequency of cyclonic tracks, and dynamic and kinematic parameters, such as intensity, size, propagation velocity, as well as trend analysis. For this purpose, the MPI-HH regional coupled climate model of the Max Planck Institute for Meteorology is employed consisting of the REgional atmosphere MOdel (REMO), the Max-Planck-Institute for Meteorology ocean model (MPI-OM) and the Hydrological Discharge Model (HD Model). A 25 km resolution domain is established on a rotated latitude-longitude coordinate system, while the physical parameterizations are taken from the global climate model ECHAM-4. These model data became available through the EU Project CIRCE which aims to perform, for the first time, climate change projections with a realistic representation of the Mediterranean Sea. The model results for the present climate are evaluated against ERA-40 Reanalysis (available through ECMWF), for the period 1962-2001. The identification and tracking of cyclones is performed with the aid of the Melbourne University algorithm (MS algorithm), according to the Lagrangian perspective. MS algorithm characterizes a cyclone only if a vorticity maximum could be connected with a local pressure minimum. According to the results, a decrease of the storm number and a tendency towards deeper cyclones is expected in the future, in general agreement with the results of previous studies. However, new findings reveal with respect to the dynamic/kinematic characteristics of the cyclonic tracks. The model experiments verify that considerable inter-monthly variations of track density occur in the Mediterranean region. The study of the kinematic and dynamic parameters of the cyclonic tracks according to their origin domain show that the vast majority originate within the examined area itself. ACKNOWLEDGMENTS: M. Hatzaki would like to thank the Greek State Scholarships Foundation for financial support through the program of postdoctoral research. The support of EU-FP6 project CIRCE Integrated Project-Climate Change and Impact Research: the Mediterranean Environment (http://www.circeproject.eu) for climate model data provision is also greatly acknowledged.

A Parametric Study of Slag Skin Formation in Electroslag Remelting

NASA Astrophysics Data System (ADS)

Yanke, Jeff; Krane, Matthew John M.

In electroslag remelting (ESR), the slag generates heat, chemically refines the melting electrode material, and forms frozen skin on the mold. An axisymmetric model is used to simulate fluid flow, heat transfer, solidification, and electromagnetics and their interaction with slag skin formation in ESR. A volume of fluid (VOF) method is used to track the slag/metal interface, allowing simulation of slag freezing to the mold. Mold diameter and applied current are varied to determine how these parameters affect melt rate and formation of slag skin during ESR. Variations in the slag skin thickness within the slag cap are found to have a significant impact on melt rate and depth of metal sump. Changes in slag cap volume resulted in small changes in melt rate.

Motion compensation for in vivo subcellular optical microscopy.

PubMed

Lucotte, B; Balaban, R S

2014-04-01

In this review, we focus on the impact of tissue motion on attempting to conduct subcellular resolution optical microscopy, in vivo. Our position is that tissue motion is one of the major barriers in conducting these studies along with light induced damage, optical probe loading as well as absorbing and scattering effects on the excitation point spread function and collection of emitted light. Recent developments in the speed of image acquisition have reached the limit, in most cases, where the signal from a subcellular voxel limits the speed and not the scanning rate of the microscope. Different schemes for compensating for tissue displacements due to rigid body and deformation are presented from tissue restriction, gating, adaptive gating and active tissue tracking. We argue that methods that minimally impact the natural physiological motion of the tissue are desirable because the major reason to perform in vivo studies is to evaluate normal physiological functions. Towards this goal, active tracking using the optical imaging data itself to monitor tissue displacement and either prospectively or retrospectively correct for the motion without affecting physiological processes is desirable. Critical for this development was the implementation of near real time image processing in conjunction with the control of the microscope imaging parameters. Clearly, the continuing development of methods of motion compensation as well as significant technological solutions to the other barriers to tissue subcellular optical imaging in vivo, including optical aberrations and overall signal-to-noise ratio, will make major contributions to the understanding of cell biology within the body.

Development and Application of an Objective Tracking Algorithm for Tropical Cyclones over the North-West Pacific purely based on Wind Speeds

NASA Astrophysics Data System (ADS)

Befort, Daniel J.; Kruschke, Tim; Leckebusch, Gregor C.

2017-04-01

Tropical Cyclones over East Asia have huge socio-economic impacts due to their strong wind fields and large rainfall amounts. Especially, the most severe events are associated with huge economic losses, e.g. Typhoon Herb in 1996 is related to overall losses exceeding 5 billion US (Munich Re, 2016). In this study, an objective tracking algorithm is applied to JRA55 reanalysis data from 1979 to 2014 over the Western North Pacific. For this purpose, a purely wind based algorithm, formerly used to identify extra-tropical wind storms, has been further developed. The algorithm is based on the exceedance of the local 98th percentile to define strong wind fields in gridded climate data. To be detected as a tropical cyclone candidate, the following criteria must be fulfilled: 1) the wind storm must exist for at least eight 6-hourly time steps and 2) the wind field must exceed a minimum size of 130.000km2 for each time step. The usage of wind information is motivated to focus on damage related events, however, a pre-selection based on the affected region is necessary to remove events of extra-tropical nature. Using IBTrACS Best Tracks for validation, it is found that about 62% of all detected tropical cyclone events in JRA55 reanalysis can be matched to an observed best track. As expected the relative amount of matched tracks increases with the wind intensity of the event, with a hit rate of about 98% for Violent Typhoons, above 90% for Very Strong Typhoons and about 75% for Typhoons. Overall these results are encouraging as the parameters used to detect tropical cyclones in JRA55, e.g. minimum area, are also suitable to detect TCs in most CMIP5 simulations and will thus allow estimates of potential future changes.

A Track Initiation Method for the Underwater Target Tracking Environment

NASA Astrophysics Data System (ADS)

Li, Dong-dong; Lin, Yang; Zhang, Yao

2018-04-01

A novel efficient track initiation method is proposed for the harsh underwater target tracking environment (heavy clutter and large measurement errors): track splitting, evaluating, pruning and merging method (TSEPM). Track initiation demands that the method should determine the existence and initial state of a target quickly and correctly. Heavy clutter and large measurement errors certainly pose additional difficulties and challenges, which deteriorate and complicate the track initiation in the harsh underwater target tracking environment. There are three primary shortcomings for the current track initiation methods to initialize a target: (a) they cannot eliminate the turbulences of clutter effectively; (b) there may be a high false alarm probability and low detection probability of a track; (c) they cannot estimate the initial state for a new confirmed track correctly. Based on the multiple hypotheses tracking principle and modified logic-based track initiation method, in order to increase the detection probability of a track, track splitting creates a large number of tracks which include the true track originated from the target. And in order to decrease the false alarm probability, based on the evaluation mechanism, track pruning and track merging are proposed to reduce the false tracks. TSEPM method can deal with the track initiation problems derived from heavy clutter and large measurement errors, determine the target's existence and estimate its initial state with the least squares method. What's more, our method is fully automatic and does not require any kind manual input for initializing and tuning any parameter. Simulation results indicate that our new method improves significantly the performance of the track initiation in the harsh underwater target tracking environment.

Repeatability of DTI-based skeletal muscle fiber tracking

PubMed Central

Heemskerk, Anneriet M.; Sinha, Tuhin K.; Wilson, Kevin J.; Ding, Zhaohua; Damon, Bruce M.

2015-01-01

Diffusion tensor imaging (DTI)-based muscle fiber tracking enables the measurement of muscle architectural parameters, such as pennation angle (θ) and fiber tract length (Lft), throughout the entire muscle. Little is known, however, about the repeatability of either the muscle architectural measures or the underlying diffusion measures. Therefore, the goal of this study was to investigate the repeatability of DTI fiber tracking-based measurements and θ and Lft. Four DTI acquisitions were performed on two days that allowed for between acquisition, within day, and between day analyses. The eigenvalues and fractional anisotropy were calculated at the maximum cross-sectional area of, and fiber tracking was performed in, the tibialis anterior muscle of nine healthy subjects. The between acquisitions condition had the highest repeatability for the DTI indices and the architectural parameters. The overall inter class correlation coefficients (ICC’s) were greater than 0.6 for both θ and Lft and the repeatability coefficients were θ <10.2° and Lft < 50 mm. In conclusion, under the experimental and data analysis conditions used, the repeatability of the diffusion measures is very good and repeatability of the architectural measurements is acceptable. Therefore, this study demonstrates the feasibility for longitudinal studies of alterations in muscle architecture using DTI-based fiber tracking, under similar noise conditions and with similar diffusion characteristics. PMID:20099372

Four-dimensional guidance algorithms for aircraft in an air traffic control environment

NASA Technical Reports Server (NTRS)

Pecsvaradi, T.

1975-01-01

Theoretical development and computer implementation of three guidance algorithms are presented. From a small set of input parameters the algorithms generate the ground track, altitude profile, and speed profile required to implement an experimental 4-D guidance system. Given a sequence of waypoints that define a nominal flight path, the first algorithm generates a realistic, flyable ground track consisting of a sequence of straight line segments and circular arcs. Each circular turn is constrained by the minimum turning radius of the aircraft. The ground track and the specified waypoint altitudes are used as inputs to the second algorithm which generates the altitude profile. The altitude profile consists of piecewise constant flight path angle segments, each segment lying within specified upper and lower bounds. The third algorithm generates a feasible speed profile subject to constraints on the rate of change in speed, permissible speed ranges, and effects of wind. Flight path parameters are then combined into a chronological sequence to form the 4-D guidance vectors. These vectors can be used to drive the autopilot/autothrottle of the aircraft so that a 4-D flight path could be tracked completely automatically; or these vectors may be used to drive the flight director and other cockpit displays, thereby enabling the pilot to track a 4-D flight path manually.

Development of robust behaviour recognition for an at-home biomonitoring robot with assistance of subject localization and enhanced visual tracking.

PubMed

Imamoglu, Nevrez; Dorronzoro, Enrique; Wei, Zhixuan; Shi, Huangjun; Sekine, Masashi; González, José; Gu, Dongyun; Chen, Weidong; Yu, Wenwei

2014-01-01

Our research is focused on the development of an at-home health care biomonitoring mobile robot for the people in demand. Main task of the robot is to detect and track a designated subject while recognizing his/her activity for analysis and to provide warning in an emergency. In order to push forward the system towards its real application, in this study, we tested the robustness of the robot system with several major environment changes, control parameter changes, and subject variation. First, an improved color tracker was analyzed to find out the limitations and constraints of the robot visual tracking considering the suitable illumination values and tracking distance intervals. Then, regarding subject safety and continuous robot based subject tracking, various control parameters were tested on different layouts in a room. Finally, the main objective of the system is to find out walking activities for different patterns for further analysis. Therefore, we proposed a fast, simple, and person specific new activity recognition model by making full use of localization information, which is robust to partial occlusion. The proposed activity recognition algorithm was tested on different walking patterns with different subjects, and the results showed high recognition accuracy.

Development of Robust Behaviour Recognition for an at-Home Biomonitoring Robot with Assistance of Subject Localization and Enhanced Visual Tracking

PubMed Central

Imamoglu, Nevrez; Dorronzoro, Enrique; Wei, Zhixuan; Shi, Huangjun; González, José; Gu, Dongyun; Yu, Wenwei

2014-01-01

Our research is focused on the development of an at-home health care biomonitoring mobile robot for the people in demand. Main task of the robot is to detect and track a designated subject while recognizing his/her activity for analysis and to provide warning in an emergency. In order to push forward the system towards its real application, in this study, we tested the robustness of the robot system with several major environment changes, control parameter changes, and subject variation. First, an improved color tracker was analyzed to find out the limitations and constraints of the robot visual tracking considering the suitable illumination values and tracking distance intervals. Then, regarding subject safety and continuous robot based subject tracking, various control parameters were tested on different layouts in a room. Finally, the main objective of the system is to find out walking activities for different patterns for further analysis. Therefore, we proposed a fast, simple, and person specific new activity recognition model by making full use of localization information, which is robust to partial occlusion. The proposed activity recognition algorithm was tested on different walking patterns with different subjects, and the results showed high recognition accuracy. PMID:25587560

A Validation Study of Merging and Spacing Techniques in a NAS-Wide Simulation

NASA Technical Reports Server (NTRS)

Glaab, Patricia C.

2011-01-01

In November 2010, Intelligent Automation, Inc. (IAI) delivered an M&S software tool to that allows system level studies of the complex terminal airspace with the ACES simulation. The software was evaluated against current day arrivals in the Atlanta TRACON using Atlanta's Hartsfield-Jackson International Airport (KATL) arrival schedules. Results of this validation effort are presented describing data sets, traffic flow assumptions and techniques, and arrival rate comparisons between reported landings at Atlanta versus simulated arrivals using the same traffic sets in ACES equipped with M&S. Initial results showed the simulated system capacity to be significantly below arrival capacity seen at KATL. Data was gathered for Atlanta using commercial airport and flight tracking websites (like FlightAware.com), and analyzed to insure compatible techniques were used for result reporting and comparison. TFM operators for Atlanta were consulted for tuning final simulation parameters and for guidance in flow management techniques during high volume operations. Using these modified parameters and incorporating TFM guidance for efficiencies in flowing aircraft, arrival capacity for KATL was matched for the simulation. Following this validation effort, a sensitivity study was conducted to measure the impact of variations in system parameters on the Atlanta airport arrival capacity.

Gender Differences in Context: The Impact of Track Position on Study Involvement in Flemish Secondary Education

ERIC Educational Resources Information Center

Van Houtte, Mieke

2017-01-01

This study examines whether the influence of track position on study involvement is gendered and whether gender differences in study involvement according to track position are associated with school misconduct and rather poor future perspectives. Three-level analyses (HLM 6) of data gathered in 2004-2005 from 11,872 third- and fifth-grade…

On Using Exponential Parameter Estimators with an Adaptive Controller

NASA Technical Reports Server (NTRS)

Patre, Parag; Joshi, Suresh M.

2011-01-01

Typical adaptive controllers are restricted to using a specific update law to generate parameter estimates. This paper investigates the possibility of using any exponential parameter estimator with an adaptive controller such that the system tracks a desired trajectory. The goal is to provide flexibility in choosing any update law suitable for a given application. The development relies on a previously developed concept of controller/update law modularity in the adaptive control literature, and the use of a converse Lyapunov-like theorem. Stability analysis is presented to derive gain conditions under which this is possible, and inferences are made about the tracking error performance. The development is based on a class of Euler-Lagrange systems that are used to model various engineering systems including space robots and manipulators.

An empirical-statistical model for laser cladding of Ti-6Al-4V powder on Ti-6Al-4V substrate

NASA Astrophysics Data System (ADS)

Nabhani, Mohammad; Razavi, Reza Shoja; Barekat, Masoud

2018-03-01

In this article, Ti-6Al-4V powder alloy was directly deposited on Ti-6Al-4V substrate using laser cladding process. In this process, some key parameters such as laser power (P), laser scanning rate (V) and powder feeding rate (F) play important roles. Using linear regression analysis, this paper develops the empirical-statistical relation between these key parameters and geometrical characteristics of single clad tracks (i.e. clad height, clad width, penetration depth, wetting angle, and dilution) as a combined parameter (PαVβFγ). The results indicated that the clad width linearly depended on PV-1/3 and powder feeding rate had no effect on it. The dilution controlled by a combined parameter as VF-1/2 and laser power was a dispensable factor. However, laser power was the dominant factor for the clad height, penetration depth, and wetting angle so that they were proportional to PV-1F1/4, PVF-1/8, and P3/4V-1F-1/4, respectively. Based on the results of correlation coefficient (R > 0.9) and analysis of residuals, it was confirmed that these empirical-statistical relations were in good agreement with the measured values of single clad tracks. Finally, these relations led to the design of a processing map that can predict the geometrical characteristics of the single clad tracks based on the key parameters.

Air-Breathing Hypersonic Vehicle Tracking Control Based on Adaptive Dynamic Programming.

PubMed

Mu, Chaoxu; Ni, Zhen; Sun, Changyin; He, Haibo

2017-03-01

In this paper, we propose a data-driven supplementary control approach with adaptive learning capability for air-breathing hypersonic vehicle tracking control based on action-dependent heuristic dynamic programming (ADHDP). The control action is generated by the combination of sliding mode control (SMC) and the ADHDP controller to track the desired velocity and the desired altitude. In particular, the ADHDP controller observes the differences between the actual velocity/altitude and the desired velocity/altitude, and then provides a supplementary control action accordingly. The ADHDP controller does not rely on the accurate mathematical model function and is data driven. Meanwhile, it is capable to adjust its parameters online over time under various working conditions, which is very suitable for hypersonic vehicle system with parameter uncertainties and disturbances. We verify the adaptive supplementary control approach versus the traditional SMC in the cruising flight, and provide three simulation studies to illustrate the improved performance with the proposed approach.

Singularity-free backstepping controller for model helicopters.

PubMed

Zou, Yao; Huo, Wei

2016-11-01

This paper develops a backstepping controller for model helicopters to achieve trajectory tracking without singularity, which occurs in the attitude representation when the roll or pitch reaches ±π2. Based on a simplified model with unmodeled dynamics, backstepping technique is introduced to exploit the controller and hyperbolic tangent functions are utilized to compensate the unmodeled dynamics. Firstly, a position loop controller is designed for the position tracking, where an auxiliary dynamic system with suitable parameters is introduced to warrant the singularity-free requirement for the extracted command attitude. Then, a novel attitude loop controller is proposed to obviate singularity. It is demonstrated that, based on the established criteria for selecting controller parameters and desired trajectories, the proposed controller realizes the singularity-free trajectory tracking of the model helicopter. Simulations confirm the theoretical results. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Feast or famine? The variable impact of coexisting fellowships on general surgery resident operative volumes.

PubMed

Hanks, John B; Ashley, Stanley W; Mahvi, David M; Meredith, Wayne J; Stain, Steven C; Biester, Thomas W; Borman, Karen R

2011-09-01

Nearly 80% of general surgery residents (GSR) pursue Fellowship training. We hypothesized that fellowships coexisting with general surgery residencies do not negatively impact GSR case volumes and that fellowship-bound residents (FBR) preferentially seek out cases in their chosen specialty ("early tracking"). To test our hypotheses, we analyzed the Accreditation Council for Graduate Medical Education Surgical Operative Log data from 2009 American Board of Surgery qualifying examination applicants (N = 976). General surgery programs coexisted with 35 colorectal (CR), 97 vascular (Vasc), 80 minimally invasive (MIS), and 12 Endocrine (Endo) fellowships. We analyzed (1) operative cases for general surgery residency programs with and without coexisting Fellowships, comparing caseloads for FBR and all GSR and (2) operative cases of FBR in their chosen specialties compared to all other GSR. Group means were compared using ANOVA with significance set at P < 0.01. Coexisting fellowships had minimal impact on GSR caseloads. Endocrine fellowships actually enhanced case volumes for all residents. CR impact was neutral while MIS and vascular fellowships resulted in small declines. Endo, CR, and Vasc but not MIS FBR performed significantly more cases in their future specialties than their GSR counterparts, consistent with self-directed, prefellowship tracking. Tracking seems to be additive and FBR do not sacrifice other GSR cases. Our data establish that the impact of Fellowships on GSR caseloads is minimal. Our data confirm that FBR seek out cases in their future specialties ("early tracking").

The Holloman Test Track Impact Area Archeological Survey

DTIC Science & Technology

1988-07-25

must be addressed 23 HOLLOMAN TEST TRACK IMPACT AREA SURVEY before data from the basin floor can contribute (5) What lnds of excavation contexts ar ...and chronology can be determined or Based on these considerations, the following questions are suggested, how might survey sites be used to designed to...scatter of artifact assemblages are listed in Appendix 4. wood planks, cans , and broken glass. The glass assemblage is limited but includes a Clorox

Intraobserver reproducibility of parameters of standard and 2D speckle tracking echocardiography, dynamics of global longitudinal strain I in patients with acute primary anterior STEMI

NASA Astrophysics Data System (ADS)

Kercheva, M.; Ryabova, T.; Ryabov, V.; Karpov, R.

2015-11-01

The aim of this study was to assess the intraobserver reproducibility of parameters of standard and 2 dimensional speckle tracking echocardiography, dynamics of global longitudinal strain in patients with acute primary anterior STEMI. The study included 24 patients, mean age 58.46±10.2. Echocardiography with 2D speckle tracking imaging was performed on the 1st (T1), 7th (T2), 14th days (T3) after STEMI («Vivid E9»). Analysis of echocardiographic images was performed offline at the different periods by the two independent observers (EchoPac) - experienced and inexperienced. In order to assess the agreement between standard and 2D speckle tracking echocardiography, a correlation analysis (Pearson correlation, Spearman's rank correlation coefficient) and Bland-Altman analysis were undertaken. The 23 patients had urgent reperfusion therapy, 6 patients underwent primary PCI, 16 patients - PCI after successful fibrinolysis (68%). GLS and WMSI had the best intraobsever reproducibility. Dynamics of EDV LV, ESV LV, EF LV was without significant differences. Nevertheless, it was found positive dynamic of GLS: - 12.65±3.53 (T1), -13.61±3.81 (T2), -14.27±4.1 (T3), p<0.05. GLS reduced 11.35% (p=0.0048) from T1 to T3. The best intraobserver reproducibility of parameters of 2 D speckle-tracking and standard echocardiography was revealed in GLS and WMSI. The modern management of STEMI patients limits adverse postinfarction remodeling and preserves of global left ventricular contractility detected by the EF LV. However, GLS had the positive dynamics and improved to the 14th day.

Effect of cross-correlation on track-to-track fusion

NASA Astrophysics Data System (ADS)

Saha, Rajat K.

1994-07-01

Since the advent of target tracking systems employing a diverse mixture of sensors, there has been increasing recognition by air defense system planners and other military system analysts of the need to integrate these tracks so that a clear air picture can be obtained in a command center. A popular methodology to achieve this goal is to perform track-to-track fusion, which performs track-to-track association as well as kinematic state vector fusion. This paper seeks to answer analytically the extent of improvement achievable by means of kinetic state vector fusion when the tracks are obtained from dissimilar sensors (e.g., Radar/ESM/IRST/IFF). It is well known that evaluation of the performance of state vector fusion algorithms at steady state must take into account the effects of cross-correlation between eligible tracks introduced by the input noise which, unfortunately, is often neglected because of added computational complexity. In this paper, an expression for the steady-state cross-covariance matrix for a 2D state vector track-to-track fusion is obtained. This matrix is shown to be a function of the parameters of the Kalman filters associated with the candidate tracks being fused. Conditions for positive definiteness of the cross-covariance matrix have been derived and the effect of positive definiteness on performance of track-to-track fusion is also discussed.

Reference values of one-point carotid stiffness parameters determined by carotid echo-tracking and brachial pulse pressure in a large population of healthy subjects.

PubMed

Vriz, Olga; Aboyans, Victor; Minisini, Rosalba; Magne, Julien; Bertin, Nicole; Pirisi, Mario; Bossone, Eduardo

2017-07-01

Arterial stiffness can predict cardiovascular events, and the aim of this study was to produce age- and sex-specific reference values for echo-tracking carotid stiffness in healthy subjects. A total of 900 subjects (500 males, mean age 45.8±19 years) were enrolled. Common carotid artery stiffness and compliance, using a high-definition echo-tracking ultrasound system, were evaluated. To compare stiffness parameters across the different age groups, individual scores were transformed into T-scores, indicating how many standard deviation (s.d.) units an individual's score was above or below the mean that was observed in the group including same-sex individuals aged 36 to 44 years. Carotid stiffness was similar among genders, except compliance, which was lower in women (P<0.0001). These characteristics were also maintained when the studied population was divided into seven age groups. Stiffness parameters increased significantly with age, but the opposite occurred for compliance. The T-score was found to increase significantly across all age groups, with a steeper increase in stiffness around the age of 60 years in women. For each T-score s.d., the corresponding carotid absolute values for arterial stiffness and compliance were obtained. In a multivariate model, carotid stiffness parameters were constantly and independently associated with age, mean arterial pressure, pulse pressure, heart rate and body mass index. Our study provides a normogram of carotid arterial stiffness and compliance indices obtained with the echo-tracking method in a large population of healthy subjects stratified by gender and age that can be used in clinical practice.

The Relationship Between Extratropical Cyclone Steering and Blocking Along the North American East Coast

NASA Astrophysics Data System (ADS)

Booth, James F.; Dunn-Sigouin, Etienne; Pfahl, Stephan

2017-12-01

The path and speed of extratropical cyclones along the east coast of North America influence their societal impact. This work characterizes the climatological relationship between cyclone track path and speed, and blocking and the North Atlantic Oscillation (NAO). An analysis of Lagrangian cyclone track propagation speed and angle shows that the percentage of cyclones with blocks is larger for cyclones that propagate northward or southeastward, as is the size of the blocked region near the cyclone. Cyclone-centered composites show that propagation of cyclones relative to blocks is consistent with steering by the block: northward tracks more often have a block east/northeast of the cyclone; slow tracks tend to have blocks due north of the cyclone. Comparison with the NAO shows that to first-order blocking and the NAO steer cyclones in a similar manner. However, blocked cyclones are more likely to propagate northward, increasing the likelihood of cyclone related impacts.

Geometry modeling of single track cladding deposited by high power diode laser with rectangular beam spot

NASA Astrophysics Data System (ADS)

Liu, Huaming; Qin, Xunpeng; Huang, Song; Hu, Zeqi; Ni, Mao

2018-01-01

This paper presents an investigation on the relationship between the process parameters and geometrical characteristics of the sectional profile for the single track cladding (STC) deposited by High Power Diode Laser (HPDL) with rectangle beam spot (RBS). To obtain the geometry parameters, namely cladding width Wc and height Hc of the sectional profile, a full factorial design (FFD) of experiment was used to conduct the experiments with a total of 27. The pre-placed powder technique has been employed during laser cladding. The influence of the process parameters including laser power, powder thickness and scanning speed on the Wc and Hc was analyzed in detail. A nonlinear fitting model was used to fit the relationship between the process parameters and geometry parameters. And a circular arc was adopted to describe the geometry profile of the cross-section of STC. The above models were confirmed by all the experiments. The results indicated that the geometrical characteristics of the sectional profile of STC can be described as the circular arc, and the other geometry parameters of the sectional profile can be calculated only using Wc and Hc. Meanwhile, the Wc and Hc can be predicted through the process parameters.

Energy management and attitude control for spacecraft

NASA Astrophysics Data System (ADS)

Costic, Bret Thomas

2001-07-01

This PhD dissertation describes the design and implementation of various control strategies centered around spacecraft applications: (i) an attitude control system for spacecraft, (ii) flywheels used for combined attitude and energy tracking, and (iii) an adaptive autobalancing control algorithm. The theory found in each of these sections is demonstrated through simulation or experimental results. An introduction to each of these three primary chapters can be found in chapter one. The main problem addressed in the second chapter is the quaternion-based, attitude tracking control of rigid spacecraft without angular velocity measurements and in the presence of an unknown inertia matrix. As a stepping-stone, an adaptive, full-state feedback controller that compensates for parametric uncertainty while ensuring asymptotic attitude tracking errors is designed. The adaptive, full-state feedback controller is then redesigned such that the need for angular velocity measurements is eliminated. The proposed adaptive, output feedback controller ensures asymptotic attitude tracking. This work uses a four-parameter representation of the spacecraft attitude that does not exhibit singular orientations as in the case of the previous three-parameter representation-based results. To the best of my knowledge, this represents the first solution to the adaptive, output feedback, attitude tracking control problem for the quaternion representation. Simulation results are included to illustrate the performance of the proposed output feedback control strategy. The third chapter is devoted to the use of multiple flywheels that integrate the energy storage and attitude control functions in space vehicles. This concept, which is referred to as an Integrated Energy Management and Attitude Control (IEMAC) system, reduces the space vehicle bus mass, volume, cost, and maintenance requirements while maintaining or improving the space vehicle performance. To this end, two nonlinear IEMAC strategies (model-based and adaptive) that simultaneously track a desired attitude trajectory and desired energy/power profile are presented. Both strategies ensure asymptotic tracking while the adaptive controller compensates for uncertain spacecraft inertia. In the final chapter, a control strategy is designed for a rotating, unbalanced disk. The control strategy, which is composed of a control torque and two control forces, regulates the disk displacement and ensures angular velocity tracking. The controller uses a desired compensation adaptation law and a gain adjusted forgetting factor to achieve exponential stability despite the lack of knowledge of the imbalance-related parameters, provided a mild persistency of excitation condition is satisfied.

Evaluation of the measurement uncertainty when measuring the resistance of solid isolating materials to tracking

NASA Astrophysics Data System (ADS)

Stare, E.; Beges, G.; Drnovsek, J.

2006-07-01

This paper presents the results of research into the measurement of the resistance of solid isolating materials to tracking. Two types of tracking were investigated: the proof tracking index (PTI) and the comparative tracking index (CTI). Evaluation of the measurement uncertainty in a case study was performed using a test method in accordance with the IEC 60112 standard. In the scope of the tests performed here, this particular test method was used to ensure the safety of electrical appliances. According to the EN ISO/IEC 17025 standard (EN ISO/IEC 17025), in the process of conformity assessment, the evaluation of the measurement uncertainty of the test method should be carried out. In the present article, possible influential parameters that are in accordance with the third and fourth editions of the standard IEC 60112 are discussed. The differences, ambiguities or lack of guidance referring to both editions of the standard are described in the article 'Ambiguities in technical standards—case study IEC 60112—measuring the resistance of solid isolating materials to tracking' (submitted for publication). Several hundred measurements were taken in the present experiments in order to form the basis for the results and conclusions presented. A specific problem of the test (according to the IEC 60112 standard) is the great variety of influential physical parameters (mechanical, electrical, chemical, etc) that can affect the results. At the end of the present article therefore, there is a histogram containing information on the contributions to the measurement uncertainty.

Using eye-tracking technology for communication in Rett syndrome: perceptions of impact.

PubMed

Vessoyan, Kelli; Steckle, Gill; Easton, Barb; Nichols, Megan; Mok Siu, Victoria; McDougall, Janette

2018-04-27

Studies have investigated the use of eye-tracking technology to assess cognition in individuals with Rett syndrome, but few have looked at this access method for communication for this group. Loss of speech, decreased hand use, and severe motor apraxia significantly impact functional communication for this population. Eye gaze is one modality that may be used successfully by individuals with Rett syndrome. This multiple case study explored whether using eye-tracking technology, with ongoing support from a team of augmentative and alternative communication (AAC) therapists, could help four participants with Rett syndrome meet individualized communication goals. Two secondary objectives were to examine parents' perspectives on (a) the psychosocial impact of their child's use of the technology, and (b) satisfaction with using the technology. All four participants were rated by the treating therapists to have made improvement on their goals. According to both quantitative findings and descriptive information, eye-tracking technology was viewed by parents as contributing to participants' improved psychosocial functioning. Parents reported being highly satisfied with both the device and the clinical services received. This study provides initial evidence that eye-tracking may be perceived as a worthwhile and potentially satisfactory technology to support individuals with Rett syndrome in communicating. Future, more rigorous research that addresses the limitations of a case study design is required to substantiate study findings.

Impact of x-ray dose on the response of CR-39 to 1–5.5 MeV alphas

DOE PAGES

Rojas-Herrera, J.; Rinderknecht, H. G.; Zylstra, A. B.; ...

2015-03-01

The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray uences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-K α and K β x-rays. The CR-39 detectors were then exposed to 1-5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those notmore » exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula.« less

Manual control analysis of drug effects on driving performance

NASA Technical Reports Server (NTRS)

Smiley, A.; Ziedman, K.; Moskowitz, H.

1981-01-01

The effects of secobarbital, diazepam, alcohol, and marihuana on car-driver transfer functions obtained using a driving simulator were studied. The first three substances, all CNS depressants, reduced gain, crossover frequency, and coherence which resulted in poorer tracking performance. Marihuana also impaired tracking performance but the only effect on the transfer function parameters was to reduce coherence.

Modeling human tracking error in several different anti-tank systems

NASA Technical Reports Server (NTRS)

Kleinman, D. L.

1981-01-01

An optimal control model for generating time histories of human tracking errors in antitank systems is outlined. Monte Carlo simulations of human operator responses for three Army antitank systems are compared. System/manipulator dependent data comparisons reflecting human operator limitations in perceiving displayed quantities and executing intended control motions are presented. Motor noise parameters are also discussed.

Dynamic response of the train-track-bridge system subjected to derailment impacts

NASA Astrophysics Data System (ADS)

Ling, Liang; Dhanasekar, Manicka; Thambiratnam, David P.

2018-04-01

Derailments on bridges, although not frequent, when occurs due to a complex dynamic interaction of the train-track-bridge structural system, are very severe. Furthermore, the forced vibration induced by the post-derailment impacts can toss out the derailed wagons from the bridge deck with severe consequences to the traffic underneath and the safety of the occupants of the wagons. This paper presents a study of the train-track-bridge interaction during a heavy freight train crossing a concrete box girder bridge from a normal operation to a derailed state. A numerical model that considers the bridge vibration, train-track interaction and the train post-derailment behaviour is formulated based on a coupled finite-element - multi-body dynamics (FE-MBD) theory. The model is applied to predict the post-derailment behaviour of a freight train composed of one locomotive and several wagons, as well as the dynamic response of a straight single-span simply supported bridge containing ballast track subjected to derailment impacts. For this purpose, a typical derailment scenario of a heavy freight train passing over a severe track geometry defect is introduced. The dynamic derailment behaviour of the heavy freight train and the dynamic responses of the rail bridge are illustrated through numerical examples. The results exhibit the potential for tossing out of the derailed trains from the unstable increase in the yaw angle signature and a lower rate of increase of the bridge deck bending moment compared to the increase in the static axle load of the derailed wheelset.

Post-breeding migration of Dutch-breeding black-tailed godwits: timing, routes, use of stopovers, and nonbreeding destinations

USGS Publications Warehouse

Hooijmeijer, Jos C. E. W.; Senner, Nathan R.; Tibbitts, T. Lee; Gill, Robert E.; Douglas, David C.; Bruinzeel, Leo W.; Wymenga, Eddy; Piersma, Theunis

2014-01-01

Conservation of long-distance migratory shorebirds is complex because these species use habitats spread across continents and hemispheres, making identification of critical habitats and potential bottlenecks in the annual cycle especially difficult. The population of Black-tailed Godwits that breeds in Western Europe, Limosa limosa limosa, has declined precipitously over the past few decades. Despite significant efforts to identify the root causes of this decline, much remains unclear. To better understand the migratory timing, use of stopover and nonbreeding sites, and the potential impact of breeding success on these parameters, we attached 15 Argos satellite transmitters and 10 geolocation tracking devices to adult godwits nearing completion of incubation at breeding sites in southwest Friesland, The Netherlands during the spring of 2009. We successfully tracked 16 adult godwits for their entire southward migration and two others for part of it. Three migration patterns and four regions of use were apparent. Most godwits left their breeding sites and proceeded south directly to stopover sites in the Mediterranean — e.g. Spain, Portugal, and Morocco — before flying on to non-breeding sites in West Africa. Other individuals spent the entire nonbreeding season in the Mediterranean. A third pattern included a few individuals that flew nonstop from their Dutch breeding sites to nonbreeding sites in West Africa. Tracking data from this study will be immediately useful for conservation efforts focused on preserving the dispersed network of sites used by godwits during their southward migration.

Integrity monitoring of IGS products

NASA Technical Reports Server (NTRS)

Zumberge, James F.; Plag, H. -P.

2005-01-01

The IGS has successfully produced precise GPS and GLONASS transmitter parameters, coordinates of IGS tracking stations, Earth rotation parameters, and atmospheric parameters. In this paper we discuss the concepts of integrity monitoring, system monitoring, and performance assessment, all in the context of IGS products. We report on a recent survey of IGS product users, and propose an integrity strategy for the IGS.

Solar Flare Track Exposure Ages in Regolith Particles: A Calibration for Transmission Electron Microscope Measurements

NASA Technical Reports Server (NTRS)

Berger, Eve L.; Keller, Lindsay P.

2015-01-01

Mineral grains in lunar and asteroidal regolith samples provide a unique record of their interaction with the space environment. Space weathering effects result from multiple processes including: exposure to the solar wind, which results in ion damage and implantation effects that are preserved in the rims of grains (typically the outermost 100 nm); cosmic ray and solar flare activity, which result in track formation; and impact processes that result in the accumulation of vapor-deposited elements, impact melts and adhering grains on particle surfaces. Determining the rate at which these effects accumulate in the grains during their space exposure is critical to studies of the surface evolution of airless bodies. Solar flare energetic particles (mainly Fe-group nuclei) have a penetration depth of a few millimeters and leave a trail of ionization damage in insulating materials that is readily observable by transmission electron microscope (TEM) imaging. The density of solar flare particle tracks is used to infer the length of time an object was at or near the regolith surface (i.e., its exposure age). Track measurements by TEM methods are routine, yet track production rate calibrations have only been determined using chemical etching techniques [e.g., 1, and references therein]. We used focused ion beam-scanning electron microscope (FIB-SEM) sample preparation techniques combined with TEM imaging to determine the track density/exposure age relations for lunar rock 64455. The 64455 sample was used earlier by [2] to determine a track production rate by chemical etching of tracks in anorthite. Here, we show that combined FIB/TEM techniques provide a more accurate determination of a track production rate and also allow us to extend the calibration to solar flare tracks in olivine.

Bee++: An Object-Oriented, Agent-Based Simulator for Honey Bee Colonies

PubMed Central

Betti, Matthew; LeClair, Josh; Wahl, Lindi M.; Zamir, Mair

2017-01-01

We present a model and associated simulation package (www.beeplusplus.ca) to capture the natural dynamics of a honey bee colony in a spatially-explicit landscape, with temporally-variable, weather-dependent parameters. The simulation tracks bees of different ages and castes, food stores within the colony, pollen and nectar sources and the spatial position of individual foragers outside the hive. We track explicitly the intake of pesticides in individual bees and their ability to metabolize these toxins, such that the impact of sub-lethal doses of pesticides can be explored. Moreover, pathogen populations (in particular, Nosema apis, Nosema cerenae and Varroa mites) have been included in the model and may be introduced at any time or location. The ability to study interactions among pesticides, climate, biodiversity and pathogens in this predictive framework should prove useful to a wide range of researchers studying honey bee populations. To this end, the simulation package is written in open source, object-oriented code (C++) and can be easily modified by the user. Here, we demonstrate the use of the model by exploring the effects of sub-lethal pesticide exposure on the flight behaviour of foragers. PMID:28287445

Fluctuations in Conjunction Miss Distance Projections as Time Approaches Time of Closest Approach

NASA Technical Reports Server (NTRS)

Christian, John A., III

2005-01-01

A responsibility of the Trajectory Operations Officer is to ensure that the International Space Station (ISS) avoids colliding with debris. United States Space Command (USSPACECOM) tracks and catalogs a portion of the debris in Earth orbit, but only objects with a perigee less than 600 km and a radar cross section (RCS) greater than 10 cm-objects that, in fact, represent only a small fraction of the objects in Earth orbit. To accommodate for this, the ISS uses shielding to protect against collisions with smaller objects. This study provides a better understanding of how quickly, and to what degree, USSPACECOM projections tend to converge to the final, true miss distance. The information included is formulated to better predict the behavior of miss distance data during real-time operations. It was determined that the driving components, in order of impact on miss distance fluctuations, are energy dissipation rate (EDR), RCS, and inclination. Data used in this analysis, calculations made, and conclusions drawn are stored in Microsoft Excel log sheets. A separate log sheet, created for each conjunction, contains information such as predicted miss distances, apogee and perigee of debris orbit, EDR, RCS, inclination, tracks and observations, statistical data, and other evaluation/orbital parameters.

Impact of humidity on functionality of on-paper printed electronics.

PubMed

Bollström, Roger; Pettersson, Fredrik; Dolietis, Peter; Preston, Janet; Osterbacka, Ronald; Toivakka, Martti

2014-03-07

A multilayer coated paper substrate, combining barrier and printability properties was manufactured utilizing a pilot-scale slide curtain coating technique. The coating structure consists of a thin mineral pigment layer coated on top of a barrier layer. The surface properties, i.e. smoothness and surface porosity, were adjusted by the choice of calendering parameters. The influence of surface properties on the fine line printability and conductivity of inkjet-printed silver lines was studied. Surface roughness played a significant role when printing narrow lines, increasing the risk of defects and discontinuities, whereas for wider lines the influence of surface roughness was less critical. A smooth, calendered surface resulted in finer line definition, i.e. less edge raggedness. Dimensional stability and its influence on substrate surface properties as well as on the functionality of conductive tracks and transistors were studied by exposure to high/low humidity cycles. The barrier layer of the multilayer coated paper reduced the dimensional changes and surface roughness increase caused by humidity and helped maintain the conductivity of the printed tracks. Functionality of a printed transistor during a short, one hour humidity cycle was maintained, but a longer exposure to humidity destroyed the non-encapsulated transistor.

Efficiently reducing transition curvature in heat-assisted magnetic recording with state-of-the-art write heads

NASA Astrophysics Data System (ADS)

Vogler, Christoph; Abert, Claas; Bruckner, Florian; Suess, Dieter

2017-05-01

Curvatures of bit transitions on granular media are a serious problem for the read-back process. We address this fundamental issue and propose a possibility to efficiently reduce transition curvatures with state-of-the-art heat-assisted magnetic recording heads. We compare footprints of conventional with those of the proposed head design on different media, consisting of exchange coupled and single phase grains. Additionally, we investigate the impact of various recording parameters, such as the full width at half maximum (FWHM) of the applied heat pulse and the coercivity gradient near the write temperature of the recording grains. The footprints are calculated with a coarse grained model, based on the Landau-Lifshitz-Bloch equation. The presented simulations show a transition curvature reduction of up to 40%, in the case of a medium with exchange coupled grains and a heat pulse with a FWHM of 40 nm. We further give the reason for the straightening of the bit transitions, by means of basic considerations with regard to the effective recording time window of the write process. Besides the transition curvature reduction, the proposed head design yields an improvement of the transition jitter in both down-track and off-track directions.

A practical method of estimating standard error of age in the fission track dating method

USGS Publications Warehouse

Johnson, N.M.; McGee, V.E.; Naeser, C.W.

1979-01-01

A first-order approximation formula for the propagation of error in the fission track age equation is given by PA = C[P2s+P2i+P2??-2rPsPi] 1 2, where PA, Ps, Pi and P?? are the percentage error of age, of spontaneous track density, of induced track density, and of neutron dose, respectively, and C is a constant. The correlation, r, between spontaneous are induced track densities is a crucial element in the error analysis, acting generally to improve the standard error of age. In addition, the correlation parameter r is instrumental is specifying the level of neutron dose, a controlled variable, which will minimize the standard error of age. The results from the approximation equation agree closely with the results from an independent statistical model for the propagation of errors in the fission-track dating method. ?? 1979.

A Study of Running Safety and Ride Comfort of Floating Tracks for High-Speed Train

NASA Astrophysics Data System (ADS)

Watanabe, Tsutomu; Sogabe, Masamichi; Yamazaki, Takayuki

In order to reduce train-induced vibration, many floating tracks have been used, however, for only low-speed trains because we are not sure whether riding comfort and running safety can be maintained on floating tracks for high speed train. The authors, in this study, carried out an analysis of dynamic response and running quality of various floating tracks for high-speed train like Shinkansen. We used a simulation program, DIASTARS for the analysis. In this program, the Shinkansen vehicle is represented by a model of three dimensions consisting of a body, two trucks, and four wheelsets connected to each other with springs and dampers. The floating tracks were modeled by three-dimensional finite element method. In this study, the wheel load fluctuation and vehicle body accelerations were investigated by a dynamic interaction analysis between the vehicle and track with the train speed as parameters.

H∞ output tracking control of discrete-time nonlinear systems via standard neural network models.

PubMed

Liu, Meiqin; Zhang, Senlin; Chen, Haiyang; Sheng, Weihua

2014-10-01

This brief proposes an output tracking control for a class of discrete-time nonlinear systems with disturbances. A standard neural network model is used to represent discrete-time nonlinear systems whose nonlinearity satisfies the sector conditions. H∞ control performance for the closed-loop system including the standard neural network model, the reference model, and state feedback controller is analyzed using Lyapunov-Krasovskii stability theorem and linear matrix inequality (LMI) approach. The H∞ controller, of which the parameters are obtained by solving LMIs, guarantees that the output of the closed-loop system closely tracks the output of a given reference model well, and reduces the influence of disturbances on the tracking error. Three numerical examples are provided to show the effectiveness of the proposed H∞ output tracking design approach.

Real-time target tracking and locating system for UAV

NASA Astrophysics Data System (ADS)

Zhang, Chao; Tang, Linbo; Fu, Huiquan; Li, Maowen

2017-07-01

In order to achieve real-time target tracking and locating for UAV, a reliable processing system is built on the embedded platform. Firstly, the video image is acquired in real time by the photovoltaic system on the UAV. When the target information is known, KCF tracking algorithm is adopted to track the target. Then, the servo is controlled to rotate with the target, when the target is in the center of the image, the laser ranging module is opened to obtain the distance between the UAV and the target. Finally, to combine with UAV flight parameters obtained by BeiDou navigation system, through the target location algorithm to calculate the geodetic coordinates of the target. The results show that the system is stable for real-time tracking of targets and positioning.

Determination of time zero from a charged particle detector

DOEpatents

Green, Jesse Andrew [Los Alamos, NM

2011-03-15

A method, system and computer program is used to determine a linear track having a good fit to a most likely or expected path of charged particle passing through a charged particle detector having a plurality of drift cells. Hit signals from the charged particle detector are associated with a particular charged particle track. An initial estimate of time zero is made from these hit signals and linear tracks are then fit to drift radii for each particular time-zero estimate. The linear track having the best fit is then searched and selected and errors in fit and tracking parameters computed. The use of large and expensive fast detectors needed to time zero in the charged particle detectors can be avoided by adopting this method and system.

WWC Review of the Report "Are Tenure Track Professors Better Teachers?" What Works Clearinghouse Single Study Review

ERIC Educational Resources Information Center

What Works Clearinghouse, 2014

2014-01-01

The study reviewed here examined whether taking a course with a tenure track professor versus a non-tenure track professor for first-term freshman-level courses (e.g., introductory economics) had an impact on students' future enrollment and performance in classes in the same subject. Data from 15,662 students who entered Northwestern University,…

OSSE Evaluation of Aircraft Reconnaissance Observations and their Impact on Hurricane Analyses and Forecasts

NASA Astrophysics Data System (ADS)

Ryan, K. E.; Bucci, L. R.; Delgado, J.; Atlas, R. M.; Murillo, S.; Dodge, P.

2016-12-01

NOAA/AOML's Hurricane Research Division (HRD) annually conducts its Hurricane Field Program during which observations are collected via NOAA aircraft to improve the understanding and prediction of hurricanes. Mission experiments suggest a variety of flight patterns and sampling strategies aimed towards their respective goals described by the Intensity Forecasting Experiment (IFEX; Rogers et al., BAMS, 2006, 2013), a collaborative effort among HRD, NHC, and EMC. Evaluating the potential impact of various trade-offs in track design is valuable for determining the optimal air reconnaissance flight pattern for a prospective mission. AOML's HRD has developed a system for performing regional Observing System Simulation Experiments (OSSEs) to assess the potential impact of proposed observing systems on hurricane track and intensity forecasts and analyses. This study focuses on investigating the potential impact of proposed aircraft reconnaissance observing system designs. Aircraft instrument and flight level retrievals were simulated from a regional WRF ARW Nature Run (Nolan et al., 2013) spanning 13 days, covering the life cycle of a rapidly intensifying Atlantic tropical cyclone. The aircraft trajectories of NOAA aircraft are simulated in a variety of ways and are evaluated to examine the potential impact of aircraft reconnaissance observations on hurricane track and intensity forecasts.

Non-Random Spatial Distribution of Impacts in the Stardust Cometary Collector

NASA Technical Reports Server (NTRS)

Westphal, Andrew J.; Bastien, Ronald K.; Borg, Janet; Bridges, John; Brownlee, Donald E.; Burchell, Mark J.; Cheng, Andrew F.; Clark, Benton C.; Djouadi, Zahia; Floss, Christine

2007-01-01

In January 2004, the Stardust spacecraft flew through the coma of comet P81/Wild2 at a relative speed of 6.1 km/sec. Cometary dust was collected at in a 0.1 sq m collector consisting of aerogel tiles and aluminum foils. Two years later, the samples successfully returned to earth and were recovered. We report the discovery that impacts in the Stardust cometary collector are not distributed randomly in the collecting media, but appear to be clustered on scales smaller than approx.10 cm. We also report the discovery of at least two populations of oblique tracks. We evaluated several hypotheses that could explain the observations. No hypothesis was consistent with all the observations, but the preponderance of evidence points toward at least one impact on the central Whipple shield of the spacecraft as the origin of both clustering and low-angle oblique tracks. High-angle oblique tracks unambiguously originate from a noncometary impact on the spacecraft bus just forward of the collector. Here we summarize the observations, and review the evidence for and against three scenarios that we have considered for explaining the impact clustering found on the Stardust aerogel and foil collectors.

An adaptive optimal control for smart structures based on the subspace tracking identification technique

NASA Astrophysics Data System (ADS)

Ripamonti, Francesco; Resta, Ferruccio; Borroni, Massimo; Cazzulani, Gabriele

2014-04-01

A new method for the real-time identification of mechanical system modal parameters is used in order to design different adaptive control logics aiming to reduce the vibrations in a carbon fiber plate smart structure. It is instrumented with three piezoelectric actuators, three accelerometers and three strain gauges. The real-time identification is based on a recursive subspace tracking algorithm whose outputs are elaborated by an ARMA model. A statistical approach is finally applied to choose the modal parameter correct values. These are given in input to model-based control logics such as a gain scheduling and an adaptive LQR control.

On the overriding issue of train front end collision in rail vehicle dynamics

NASA Astrophysics Data System (ADS)

Yang, Chao; Li, Qiang; Xiao, Shoune; Wang, Xi

2018-04-01

A three-dimensional dynamic model of crashed vehicles coupled with moving tracks is developed to research the dynamic behaviour of the train front end collision on tangent tracks. The three-dimensional dynamic model consists of a crashed vehicle model, moving track models, a simple wheel-rail contact model, a velocity-based coupler model and the model of energy absorption and anti-climbing devices. The vector method dealing with the nonlinear wheel-rail geometry is put forward in the paper. The developed model is applicable in the scope that central collisions occur on tangent tracks at low speeds. The examples of the vehicle impacting with a rigid wall and the train front end collision are carried out to obtain the dynamic responses of vehicles. The overriding issue is studied on the basis of the wheel rise in train collisions. The results show that the second bogie of the first colliding vehicle possesses the maximal wheel rise. The wheel rise increases with the increase of vehicles. However, the number of vehicles has tiny influence on the overriding in train collisions at low speeds. On the contrary, the impact speed has significant influence on the overriding in train collisions. The wheel rise increases rapidly if the impact speed is close to the critical speed of overriding. The large wheel rise is principally generated by the great coupler force related to the rigid impact in the axial direction.

Assessing alternatives for directional detection of a halo of weakly interacting massive particles

NASA Astrophysics Data System (ADS)

Copi, Craig J.; Krauss, Lawrence M.; Simmons-Duffin, David; Stroiney, Steven R.

2007-01-01

The future of direct terrestrial WIMP detection lies on two fronts: new, much larger low background detectors sensitive to energy deposition, and detectors with directional sensitivity. The former can explore a large range of WIMP parameter space using well-tested technology while the latter may be necessary if one is to disentangle particle physics parameters from astrophysical halo parameters. Because directional detectors will be quite difficult to construct it is worthwhile exploring in advance generally which experimental features will yield the greatest benefits at the lowest costs. We examine the sensitivity of directional detectors with varying angular tracking resolution with and without the ability to distinguish forward versus backward recoils, and compare these to the sensitivity of a detector where the track is projected onto a two-dimensional plane. The latter detector regardless of where it is placed on the Earth, can be oriented to produce a significantly better discrimination signal than a 3D detector without this capability, and with sensitivity within a factor of 2 of a full 3D tracking detector. Required event rates to distinguish signals from backgrounds for a simple isothermal halo range from the low teens in the best case to many thousands in the worst.

Automated Tracking of Cell Migration with Rapid Data Analysis.

PubMed

DuChez, Brian J

2017-09-01

Cell migration is essential for many biological processes including development, wound healing, and metastasis. However, studying cell migration often requires the time-consuming and labor-intensive task of manually tracking cells. To accelerate the task of obtaining coordinate positions of migrating cells, we have developed a graphical user interface (GUI) capable of automating the tracking of fluorescently labeled nuclei. This GUI provides an intuitive user interface that makes automated tracking accessible to researchers with no image-processing experience or familiarity with particle-tracking approaches. Using this GUI, users can interactively determine a minimum of four parameters to identify fluorescently labeled cells and automate acquisition of cell trajectories. Additional features allow for batch processing of numerous time-lapse images, curation of unwanted tracks, and subsequent statistical analysis of tracked cells. Statistical outputs allow users to evaluate migratory phenotypes, including cell speed, distance, displacement, and persistence, as well as measures of directional movement, such as forward migration index (FMI) and angular displacement. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

Mechatronic track guidance on disturbed track: the trade-off between actuator performance and wheel wear

NASA Astrophysics Data System (ADS)

Kurzeck, Bernhard; Heckmann, Andreas; Wesseler, Christoph; Rapp, Matthias

2014-05-01

Future high-speed trains are the main focus of the DLR research project Next Generation Train. One central point of the research activities is the development of mechatronic track guidance for the two-axle intermediate wagons with steerable, individually powered, independently rotating wheels. The traction motors hereby fulfil two functions; they concurrently are traction drives and steering actuators. In this paper, the influence of the track properties - line layout and track irregularities - on the performance requirements for the guidance actuator is investigated using multi-body models in SIMPACK®. In order to compromise on the design conflict between low wheel wear and low steering torque, the control parameters of the mechatronic track guidance are optimised using the DLR in-house software MOPS. Besides the track irregularities especially the increasing inclination at transition curves defines high actuator requirements due to gyroscopic effects at high speed. After introducing a limiter for the actuating variables into the control system, a good performance is achieved.

An intelligent classifier for prognosis of cardiac resynchronization therapy based on speckle-tracking echocardiograms.

PubMed

Chao, Pei-Kuang; Wang, Chun-Li; Chan, Hsiao-Lung

2012-03-01

Predicting response after cardiac resynchronization therapy (CRT) has been a challenge of cardiologists. About 30% of selected patients based on the standard selection criteria for CRT do not show response after receiving the treatment. This study is aimed to build an intelligent classifier to assist in identifying potential CRT responders by speckle-tracking radial strain based on echocardiograms. The echocardiograms analyzed were acquired before CRT from 26 patients who have received CRT. Sequential forward selection was performed on the parameters obtained by peak-strain timing and phase space reconstruction on speckle-tracking radial strain to find an optimal set of features for creating intelligent classifiers. Support vector machine (SVM) with a linear, quadratic, and polynominal kernel were tested to build classifiers to identify potential responders and non-responders for CRT by selected features. Based on random sub-sampling validation, the best classification performance is correct rate about 95% with 96-97% sensitivity and 93-94% specificity achieved by applying SVM with a quadratic kernel on a set of 3 parameters. The selected 3 parameters contain both indexes extracted by peak-strain timing and phase space reconstruction. An intelligent classifier with an averaged correct rate, sensitivity and specificity above 90% for assisting in identifying CRT responders is built by speckle-tracking radial strain. The classifier can be applied to provide objective suggestion for patient selection of CRT. Copyright © 2011 Elsevier B.V. All rights reserved.

Thermal optimum design for tracking primary mirror of Space Telescope

NASA Astrophysics Data System (ADS)

Pan, Hai-jun; Ruan, Ping; Li, Fu; Wang, Hong-Wei

2011-08-01

In the conventional method, the structural parameters of primary mirror are usually optimized just by the requirement of mechanical performance. Because the influences of structural parameters on thermal stability are not taken fully into account in this simple method, the lightweight optimum design of primary mirror usually brings the bad thermal stability, especially in the complex environment. In order to obtain better thermal stability, a new method about structure-thermal optimum design of tracking primary mirror is discussed. During the optimum process, both the lightweight ratio and thermal stability will be taken into account. The structure-thermal optimum is introduced into the analysis process and commenced after lightweight design as the secondary optimum. Using the engineering analysis of software ANSYS, a parameter finite element analysis (FEA) model of mirror is built. On the premise of appropriate lightweight ratio, the RMS of structure-thermal deformation of mirror surface and lightweight ratio are assigned to be state variables, and the maximal RMS of temperature gradient load to be object variable. The results show that certain structural parameters of tracking primary mirror have different influences on mechanical performance and thermal stability, even they are opposite. By structure-thermal optimizing, the optimized mirror model discussed in this paper has better thermal stability than the old one under the same thermal loads, which can drastically reduce difficulty in thermal control.

Characteristics of Left Atrial Deformation Parameters and Their Prognostic Impact in Patients with Pathological Left Ventricular Hypertrophy: Analysis by Speckle Tracking Echocardiography.

PubMed

Iio, Chiharuko; Inoue, Katsuji; Nishimura, Kazuhisa; Fujii, Akira; Nagai, Takayuki; Suzuki, Jun; Okura, Takafumi; Higaki, Jitsuo; Ogimoto, Akiyoshi

2015-12-01

The pathological process of left ventricular (LV) hypertrophy is associated with left atrial (LA) remodeling. This study was aimed to evaluate the prognostic value of LA strain parameters in patients with pathological LV hypertrophy. This study included 95 patients with hypertensive heart disease (HHD: n = 24), hypertrophic cardiomyopathy (HCM: n = 56), cardiac amyloidosis (CA: n = 15), and control subjects (n = 20). We used two-dimensional speckle tracking echocardiography (STE) to analyze LA global strain. LA electromechanical conduction time (EMT) at the septal (EMT-septal) and lateral wall (EMT-lateral), and their time difference (EMT-diff) were calculated. The incidence of cardiac death and heart failure hospitalization was defined as major cardiac events and that of atrial fibrillation as secondary outcome. Left atrial volume index was increased and LA booster strain was decreased in the HCM and CA groups compared with the HHD group. EMT-lateral was increased in the diseased groups compared with the control. EMT-diff was prolonged in the CA group compared with the HCM group. During the follow-up period (mean 3.4 years), major cardiac events and atrial fibrillation occurred in 17 and 13 patients, respectively. The occurrence of atrial fibrillation was associated with CA etiology, E/e', LA volume index, LAa, and EMT-lateral. The incidence of major cardiac events was independently correlated with LA volume index and EMT-diff in multivariate analysis. This study suggested that the EMT-diff could discriminate patients with a high risk of cardiac events among patients with pathological LV hypertrophy. © 2015, Wiley Periodicals, Inc.

Multiparticle Simulation of Intrabeam Scattering for SuperB

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biagini, M.; Boscolo, M.; Demma, T.

In this communication we present the structure of a multiparticle tracking code to investigate intrabeam scattering effects in low emittance colliders. Simulation results obtained with particular reference to the SuperB parameters are compared with those of conventional IBS theories.and with those of a novel semi-analythical model able to predict IBS effect in terms of emittance growths. Intrabeam scattering (IBS) is associated with multiple small angle scattering events leading to emittance growth. In most electron storage rings, the growth rates arising from IBS are usually much longer than damping times due to synchrotron radiation, and its effect is not observed. However,more » IBS growth rates increase with bunch charge density, and for machines such as SuperB, that operate with high bunch charges and very low emittances, the IBS growth rates can be large enough to observe significant emittance increase. Several formalisms have been developed for calculating IBS growth rates in storage rings, notably those by Piwinski, Bjorken and Mtingwa, and their high energy approximations. Calculations show that IBS should be manageable in both SuperB rings. However these analytical models, based on Gaussian bunch distributions, cannot investigate some interesting aspects of IBS such as its impact during the damping process and its effect on the beam distribution. We developed a multiparticle tracking code, based on the Zenkevich-Bolshakov algorithm, to investigate these effects. In this communication we present the structure of the code and some simulation results obtained with particular reference to the SuperB parameters. Simulation results are compared with those of conventional IBS theories.« less

Note: Application of CR-39 plastic nuclear track detectors for quality assurance of mixed oxide fuel pellets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kodaira, S., E-mail: koda@nirs.go.jp; Kurano, M.; Hosogane, T.

A CR-39 plastic nuclear track detector was used for quality assurance of mixed oxide fuel pellets for next-generation nuclear power plants. Plutonium (Pu) spot sizes and concentrations in the pellets are significant parameters for safe use in the plants. We developed an automatic Pu detection system based on dense α-radiation tracks in the CR-39 detectors. This system would greatly improve image processing time and measurement accuracy, and will be a powerful tool for rapid pellet quality assurance screening.

Track train dynamics analysis and test program: Methodology development for the derailment safety analysis of six-axle locomotives

NASA Technical Reports Server (NTRS)

Marcotte, P. P.; Mathewson, K. J. R.

1982-01-01

The operational safety of six axle locomotives is analyzed. A locomotive model with corresponding data on suspension characteristics, a method of track defect characterization, and a method of characterizing operational safety are used. A user oriented software package was developed as part of the methodology and was used to study the effect (on operational safety) of various locomotive parameters and operational conditions such as speed, tractive effort, and track curvature. The operational safety of three different locomotive designs was investigated.

Impacts of Changed Extratropical Storm Tracks on Arctic Sea Ice Export through Fram Strait

NASA Astrophysics Data System (ADS)

Wei, J.; Zhang, X.; Wang, Z.

2017-12-01

Studies have indicated a poleward shift of extratropical storm tracks and intensification of Arctic storm activities, in particular on the North Atlantic side of the Arctic Ocean. To improve understanding of dynamic effect on changes in Arctic sea ice mass balance, we examined the impacts of the changed storm tracks and activities on Arctic sea ice export through Fram Strait through ocean-sea ice model simulations. The model employed is the high-resolution Massachusetts Institute of Technology general circulation model (MITgcm), which was forced by the Japanese 25-year Reanalysis (JRA-25) dataset. The results show that storm-induced strong northerly wind stress can cause simultaneous response of daily sea ice export and, in turn, exert cumulative effects on interannual variability and long-term changes of sea ice export. Further analysis indicates that storm impact on sea ice export is spatially dependent. The storms occurring southeast of Fram Strait exhibit the largest impacts. The weakened intensity of winter storms in this region after 1994/95 could be responsible for the decrease of total winter sea ice export during the same time period.

Least Squares Approach to the Alignment of the Generic High Precision Tracking System

NASA Astrophysics Data System (ADS)

de Renstrom, Pawel Brückman; Haywood, Stephen

2006-04-01

A least squares method to solve a generic alignment problem of a high granularity tracking system is presented. The algorithm is based on an analytical linear expansion and allows for multiple nested fits, e.g. imposing a common vertex for groups of particle tracks is of particular interest. We present a consistent and complete recipe to impose constraints on either implicit or explicit parameters. The method has been applied to the full simulation of a subset of the ATLAS silicon tracking system. The ultimate goal is to determine ≈35,000 degrees of freedom (DoF's). We present a limited scale exercise exploring various aspects of the solution.

The limits of direct satellite tracking with the Global Positioning System (GPS)

NASA Technical Reports Server (NTRS)

Bertiger, W. I.; Yunck, T. P.

1988-01-01

Recent advances in high precision differential Global Positioning System-based satellite tracking can be applied to the more conventional direct tracking of low earth satellites. To properly evaluate the limiting accuracy of direct GPS-based tracking, it is necessary to account for the correlations between the a-priori errors in GPS states, Y-bias, and solar pressure parameters. These can be obtained by careful analysis of the GPS orbit determination process. The analysis indicates that sub-meter accuracy can be readily achieved for a user above 1000 km altitude, even when the user solution is obtained with data taken 12 hours after the data used in the GPS orbit solutions.

Real-time edge tracking using a tactile sensor

NASA Technical Reports Server (NTRS)

Berger, Alan D.; Volpe, Richard; Khosla, Pradeep K.

1989-01-01

Object recognition through the use of input from multiple sensors is an important aspect of an autonomous manipulation system. In tactile object recognition, it is necessary to determine the location and orientation of object edges and surfaces. A controller is proposed that utilizes a tactile sensor in the feedback loop of a manipulator to track along edges. In the control system, the data from the tactile sensor is first processed to find edges. The parameters of these edges are then used to generate a control signal to a hybrid controller. Theory is presented for tactile edge detection and an edge tracking controller. In addition, experimental verification of the edge tracking controller is presented.

In-laboratory development of an automatic track counting system for solid state nuclear track detectors

NASA Astrophysics Data System (ADS)

Uzun, Sefa Kemal; Demiröz, Işık; Ulus, İzzet

2017-01-01

In this study, an automatic track counting system was developed for solid state nuclear track detectors (SSNTD). Firstly the specifications of required hardware components were determined, and accordingly the CCD camera, microscope and stage motor table was supplied and integrated. The system was completed by developing parametric software with VB.Net language. Finally a set of test intended for radon activity concentration measurement was applied. According to the test results, the system was enabled for routine radon measurement. Whether the parameters of system are adjusted for another SSNTD application, it could be used for other fields of SSNTD like neutron dosimetry or heavy charged particle detection.

Privacy Impact Assessment for the Registration and Tracking System for SunWise

EPA Pesticide Factsheets

The Registration and Tracking System for SunWise collects contact information and demographics about each educator. Learn how this data is collected, used, access to the data, the purpose of data collection, and record retention policies.

MICROBIAL SOURCE TRACKING: DIFFERENT USES AND APPROACHES

EPA Science Inventory

Microbial Source Tracking (MST) methods are used to determine the origin of fecal pollution impacting natural water systems. Several methods require the isolation of pure cultures in order to develop phenotypic or genotypic fingerprint libraries of both source and water bacterial...

Privacy Impact Assessment for the Enforcement Superfund Tracking System

EPA Pesticide Factsheets

This Enforcement Superfund Tracking System (ESTS) collects publicly available information from the California Secretary of State on businesses. Learn how this data is collected, how it will be used, access to the data, and the purpose of data collection.

An exploratory clustering approach for extracting stride parameters from tracking collars on free-ranging wild animals.

PubMed

Dewhirst, Oliver P; Roskilly, Kyle; Hubel, Tatjana Y; Jordan, Neil R; Golabek, Krystyna A; McNutt, J Weldon; Wilson, Alan M

2017-02-01

Changes in stride frequency and length with speed are key parameters in animal locomotion research. They are commonly measured in a laboratory on a treadmill or by filming trained captive animals. Here, we show that a clustering approach can be used to extract these variables from data collected by a tracking collar containing a GPS module and tri-axis accelerometers and gyroscopes. The method enables stride parameters to be measured during free-ranging locomotion in natural habitats. As it does not require labelled data, it is particularly suitable for use with difficult to observe animals. The method was tested on large data sets collected from collars on free-ranging lions and African wild dogs and validated using a domestic dog. © 2017. Published by The Company of Biologists Ltd.

Multi-objective control of nonlinear boiler-turbine dynamics with actuator magnitude and rate constraints.

PubMed

Chen, Pang-Chia

2013-01-01

This paper investigates multi-objective controller design approaches for nonlinear boiler-turbine dynamics subject to actuator magnitude and rate constraints. System nonlinearity is handled by a suitable linear parameter varying system representation with drum pressure as the system varying parameter. Variation of the drum pressure is represented by suitable norm-bounded uncertainty and affine dependence on system matrices. Based on linear matrix inequality algorithms, the magnitude and rate constraints on the actuator and the deviations of fluid density and water level are formulated while the tracking abilities on the drum pressure and power output are optimized. Variation ranges of drum pressure and magnitude tracking commands are used as controller design parameters, determined according to the boiler-turbine's operation range. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

SU-E-J-112: The Impact of Cine EPID Image Acquisition Frame Rate On Markerless Soft-Tissue Tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yip, S; Rottmann, J; Berbeco, R

2014-06-01

Purpose: Although reduction of the cine EPID acquisition frame rate through multiple frame averaging may reduce hardware memory burden and decrease image noise, it can hinder the continuity of soft-tissue motion leading to poor auto-tracking results. The impact of motion blurring and image noise on the tracking performance was investigated. Methods: Phantom and patient images were acquired at a frame rate of 12.87Hz on an AS1000 portal imager. Low frame rate images were obtained by continuous frame averaging. A previously validated tracking algorithm was employed for auto-tracking. The difference between the programmed and auto-tracked positions of a Las Vegas phantommore » moving in the superior-inferior direction defined the tracking error (δ). Motion blurring was assessed by measuring the area change of the circle with the greatest depth. Additionally, lung tumors on 1747 frames acquired at eleven field angles from four radiotherapy patients are manually and automatically tracked with varying frame averaging. δ was defined by the position difference of the two tracking methods. Image noise was defined as the standard deviation of the background intensity. Motion blurring and image noise were correlated with δ using Pearson correlation coefficient (R). Results: For both phantom and patient studies, the auto-tracking errors increased at frame rates lower than 4.29Hz. Above 4.29Hz, changes in errors were negligible with δ<1.60mm. Motion blurring and image noise were observed to increase and decrease with frame averaging, respectively. Motion blurring and tracking errors were significantly correlated for the phantom (R=0.94) and patient studies (R=0.72). Moderate to poor correlation was found between image noise and tracking error with R -0.58 and -0.19 for both studies, respectively. Conclusion: An image acquisition frame rate of at least 4.29Hz is recommended for cine EPID tracking. Motion blurring in images with frame rates below 4.39Hz can substantially reduce the accuracy of auto-tracking. This work is supported in part by the Varian Medical Systems, Inc.« less

Preliminary estimates of Gulf Stream characteristics from TOPEX data and a precise gravimetric geoid

NASA Technical Reports Server (NTRS)

Rapp, Richard H.; Smith, Dru A.

1994-01-01

TOPEX sea surface height data has been used, with a gravimetric geoid, to calculate sea surface topography across the Gulf Stream. This topography was initially computed for nine tracks on cycles 21 to 29. Due to inaccurate geoid undulations on one track, results for eight tracks are reported. The sea surface topography estimates were used to calculate parameters that describe Gulf Stream characteristics from two models of the Gulf Stream. One model was based on a Gaussian representation of the velocity while the other was a hyperbolic representation of velocity or the sea surface topography. The parameters of the Gaussian velocity model fit were a width parameter, a maximum velocity value, and the location of the maximum velocity. The parameters of the hyperbolic sea surface topography model were the width, the height jump, position, and sea surface topography at the center of the stream. Both models were used for the eight tracks and nine cycles studied. Comparisons were made between the width parameters, the maximum velocities, and the height jumps. Some of the parameter estimates were found to be highly (0.9) correlated when the hyperbolic sea surface topography fit was carried out, but such correlations were reduced for either the Gaussian velocity fits or the hyperbolic velocity model fit. A comparison of the parameters derived from 1-year TOPEX data showed good agreement with values derived by Kelly (1991) using 2.5 years of Geosat data near 38 deg N, 66 deg W longitude. Accuracy of the geoid undulations used in the calculations was of order of +/- 16 cm with the accuracy of a geoid undulation difference equal to +/- 15 cm over a 100-km line in areas with good terrestrial data coverage. This paper demonstrates that our knowledge or geoid undulations and undulation differences, in a portion of the Gulf Stream region, is sufficiently accurate to determine characteristics of the jet when used with TOPEX altimeter data. The method used here has not been shown to be more accurate than methods that average altimeter data to form a reference surface used in analysis to obtain the Gulf Stream characteristics. However, the results show the geoid approach may be used in areas where lack of current meandering reduces the accuracy of the average surface procedure.

CellProfiler Tracer: exploring and validating high-throughput, time-lapse microscopy image data.

PubMed

Bray, Mark-Anthony; Carpenter, Anne E

2015-11-04

Time-lapse analysis of cellular images is an important and growing need in biology. Algorithms for cell tracking are widely available; what researchers have been missing is a single open-source software package to visualize standard tracking output (from software like CellProfiler) in a way that allows convenient assessment of track quality, especially for researchers tuning tracking parameters for high-content time-lapse experiments. This makes quality assessment and algorithm adjustment a substantial challenge, particularly when dealing with hundreds of time-lapse movies collected in a high-throughput manner. We present CellProfiler Tracer, a free and open-source tool that complements the object tracking functionality of the CellProfiler biological image analysis package. Tracer allows multi-parametric morphological data to be visualized on object tracks, providing visualizations that have already been validated within the scientific community for time-lapse experiments, and combining them with simple graph-based measures for highlighting possible tracking artifacts. CellProfiler Tracer is a useful, free tool for inspection and quality control of object tracking data, available from http://www.cellprofiler.org/tracer/.

Towards designing an optical-flow based colonoscopy tracking algorithm: a comparative study

NASA Astrophysics Data System (ADS)

Liu, Jianfei; Subramanian, Kalpathi R.; Yoo, Terry S.

2013-03-01

Automatic co-alignment of optical and virtual colonoscopy images can supplement traditional endoscopic procedures, by providing more complete information of clinical value to the gastroenterologist. In this work, we present a comparative analysis of our optical flow based technique for colonoscopy tracking, in relation to current state of the art methods, in terms of tracking accuracy, system stability, and computational efficiency. Our optical-flow based colonoscopy tracking algorithm starts with computing multi-scale dense and sparse optical flow fields to measure image displacements. Camera motion parameters are then determined from optical flow fields by employing a Focus of Expansion (FOE) constrained egomotion estimation scheme. We analyze the design choices involved in the three major components of our algorithm: dense optical flow, sparse optical flow, and egomotion estimation. Brox's optical flow method,1 due to its high accuracy, was used to compare and evaluate our multi-scale dense optical flow scheme. SIFT6 and Harris-affine features7 were used to assess the accuracy of the multi-scale sparse optical flow, because of their wide use in tracking applications; the FOE-constrained egomotion estimation was compared with collinear,2 image deformation10 and image derivative4 based egomotion estimation methods, to understand the stability of our tracking system. Two virtual colonoscopy (VC) image sequences were used in the study, since the exact camera parameters(for each frame) were known; dense optical flow results indicated that Brox's method was superior to multi-scale dense optical flow in estimating camera rotational velocities, but the final tracking errors were comparable, viz., 6mm vs. 8mm after the VC camera traveled 110mm. Our approach was computationally more efficient, averaging 7.2 sec. vs. 38 sec. per frame. SIFT and Harris affine features resulted in tracking errors of up to 70mm, while our sparse optical flow error was 6mm. The comparison among egomotion estimation algorithms showed that our FOE-constrained egomotion estimation method achieved the optimal balance between tracking accuracy and robustness. The comparative study demonstrated that our optical-flow based colonoscopy tracking algorithm maintains good accuracy and stability for routine use in clinical practice.

Survey of Motion Tracking Methods Based on Inertial Sensors: A Focus on Upper Limb Human Motion

PubMed Central

Filippeschi, Alessandro; Schmitz, Norbert; Miezal, Markus; Bleser, Gabriele; Ruffaldi, Emanuele; Stricker, Didier

2017-01-01

Motion tracking based on commercial inertial measurements units (IMUs) has been widely studied in the latter years as it is a cost-effective enabling technology for those applications in which motion tracking based on optical technologies is unsuitable. This measurement method has a high impact in human performance assessment and human-robot interaction. IMU motion tracking systems are indeed self-contained and wearable, allowing for long-lasting tracking of the user motion in situated environments. After a survey on IMU-based human tracking, five techniques for motion reconstruction were selected and compared to reconstruct a human arm motion. IMU based estimation was matched against motion tracking based on the Vicon marker-based motion tracking system considered as ground truth. Results show that all but one of the selected models perform similarly (about 35 mm average position estimation error). PMID:28587178

Impact induced depolarization of ferroelectric materials

NASA Astrophysics Data System (ADS)

Agrawal, Vinamra; Bhattacharya, Kaushik

2018-06-01

We study the large deformation dynamic behavior and the associated nonlinear electro-thermo-mechanical coupling exhibited by ferroelectric materials in adiabatic environments. This is motivated by a ferroelectric generator which involves pulsed power generation by loading the ferroelectric material with a shock, either by impact or a blast. Upon impact, a shock wave travels through the material inducing a ferroelectric to nonpolar phase transition giving rise to a large voltage difference in an open circuit situation or a large current in a closed circuit situation. In the first part of this paper, we provide a general continuum mechanical treatment of the situation assuming a sharp phase boundary that is possibly charged. We derive the governing laws, as well as the driving force acting on the phase boundary. In the second part, we use the derived equations and a particular constitutive relation that describes the ferroelectric to nonpolar phase transition to study a uniaxial plate impact problem. We develop a numerical method where the phase boundary is tracked but other discontinuities are captured using a finite volume method. We compare our results with experimental observations to find good agreement. Specifically, our model reproduces the observed exponential rise of charge as well as the resistance dependent Hugoniot. We conclude with a parameter study that provides detailed insight into various aspects of the problem.

A New Approach for Inspection of Selected Geometric Parameters of a Railway Track Using Image-Based Point Clouds

PubMed Central

Sawicki, Piotr

2018-01-01

The paper presents the results of testing a proposed image-based point clouds measuring method for geometric parameters determination of a railway track. The study was performed based on a configuration of digital images and reference control network. A DSLR (digital Single-Lens-Reflex) Nikon D5100 camera was used to acquire six digital images of the tested section of railway tracks. The dense point clouds and the 3D mesh model were generated with the use of two software systems, RealityCapture and PhotoScan, which have implemented different matching and 3D object reconstruction techniques: Multi-View Stereo and Semi-Global Matching, respectively. The study found that both applications could generate appropriate 3D models. Final meshes of 3D models were filtered with the MeshLab software. The CloudCompare application was used to determine the track gauge and cant for defined cross-sections, and the results obtained from point clouds by dense image matching techniques were compared with results of direct geodetic measurements. The obtained RMS difference in the horizontal (gauge) and vertical (cant) plane was RMS∆ < 0.45 mm. The achieved accuracy meets the accuracy condition of measurements and inspection of the rail tracks (error m < 1 mm), specified in the Polish branch railway instruction Id-14 (D-75) and the European technical norm EN 13848-4:2011. PMID:29509679

A New Approach for Inspection of Selected Geometric Parameters of a Railway Track Using Image-Based Point Clouds.

PubMed

Gabara, Grzegorz; Sawicki, Piotr

2018-03-06

The paper presents the results of testing a proposed image-based point clouds measuring method for geometric parameters determination of a railway track. The study was performed based on a configuration of digital images and reference control network. A DSLR (digital Single-Lens-Reflex) Nikon D5100 camera was used to acquire six digital images of the tested section of railway tracks. The dense point clouds and the 3D mesh model were generated with the use of two software systems, RealityCapture and PhotoScan, which have implemented different matching and 3D object reconstruction techniques: Multi-View Stereo and Semi-Global Matching, respectively. The study found that both applications could generate appropriate 3D models. Final meshes of 3D models were filtered with the MeshLab software. The CloudCompare application was used to determine the track gauge and cant for defined cross-sections, and the results obtained from point clouds by dense image matching techniques were compared with results of direct geodetic measurements. The obtained RMS difference in the horizontal (gauge) and vertical (cant) plane was RMS∆ < 0.45 mm. The achieved accuracy meets the accuracy condition of measurements and inspection of the rail tracks (error m < 1 mm), specified in the Polish branch railway instruction Id-14 (D-75) and the European technical norm EN 13848-4:2011.

Adaptive control of a quadrotor aerial vehicle with input constraints and uncertain parameters

NASA Astrophysics Data System (ADS)

Tran, Trong-Toan; Ge, Shuzhi Sam; He, Wei

2018-05-01

In this paper, we address the problem of adaptive bounded control for the trajectory tracking of a Quadrotor Aerial Vehicle (QAV) while the input saturations and uncertain parameters with the known bounds are simultaneously taken into account. First, to deal with the underactuated property of the QAV model, we decouple and construct the QAV model as a cascaded structure which consists of two fully actuated subsystems. Second, to handle the input constraints and uncertain parameters, we use a combination of the smooth saturation function and smooth projection operator in the control design. Third, to ensure the stability of the overall system of the QAV, we develop the technique for the cascaded system in the presence of both the input constraints and uncertain parameters. Finally, the region of stability of the closed-loop system is constructed explicitly, and our design ensures the asymptotic convergence of the tracking errors to the origin. The simulation results are provided to illustrate the effectiveness of the proposed method.

Correlations of Melt Pool Geometry and Process Parameters During Laser Metal Deposition by Coaxial Process Monitoring

NASA Astrophysics Data System (ADS)

Ocylok, Sörn; Alexeev, Eugen; Mann, Stefan; Weisheit, Andreas; Wissenbach, Konrad; Kelbassa, Ingomar

One major demand of today's laser metal deposition (LMD) processes is to achieve a fail-save build-up regarding changing conditions like heat accumulations. Especially for the repair of thin parts like turbine blades is the knowledge about the correlations between melt pool behavior and process parameters like laser power, feed rate and powder mass stream indispensable. The paper will show the process layout with the camera based coaxial monitoring system and the quantitative influence of the process parameters on the melt pool geometry. Therefore the diameter, length and area of the melt pool are measured by a video analytic system at various parameters and compared with the track wide in cross-sections and the laser spot diameter. The influence of changing process conditions on the melt pool is also investigated. On the base of these results an enhanced process of the build-up of a multilayer one track fillet geometry will be presented.

The OSU 275 system of satellite tracking station coordinates

NASA Technical Reports Server (NTRS)

Mueller, I. I.; Kumar, M.

1975-01-01

A brief review of the methods and data used in the OSU 275 geodetic system is given along with the summary of the results. Survey information regarding the tracking stations in the system is given in tabular form along with the geodetic and geophysical parameters, origin and orientation, Cartisian coordinates, and systematic differences with global and nonglobal geodetic systems.

Robust Design of Biological Circuits: Evolutionary Systems Biology Approach

PubMed Central

Chen, Bor-Sen; Hsu, Chih-Yuan; Liou, Jing-Jia

2011-01-01

Artificial gene circuits have been proposed to be embedded into microbial cells that function as switches, timers, oscillators, and the Boolean logic gates. Building more complex systems from these basic gene circuit components is one key advance for biologic circuit design and synthetic biology. However, the behavior of bioengineered gene circuits remains unstable and uncertain. In this study, a nonlinear stochastic system is proposed to model the biological systems with intrinsic parameter fluctuations and environmental molecular noise from the cellular context in the host cell. Based on evolutionary systems biology algorithm, the design parameters of target gene circuits can evolve to specific values in order to robustly track a desired biologic function in spite of intrinsic and environmental noise. The fitness function is selected to be inversely proportional to the tracking error so that the evolutionary biological circuit can achieve the optimal tracking mimicking the evolutionary process of a gene circuit. Finally, several design examples are given in silico with the Monte Carlo simulation to illustrate the design procedure and to confirm the robust performance of the proposed design method. The result shows that the designed gene circuits can robustly track desired behaviors with minimal errors even with nontrivial intrinsic and external noise. PMID:22187523

Tracking of electrochemical impedance of batteries

NASA Astrophysics Data System (ADS)

Piret, H.; Granjon, P.; Guillet, N.; Cattin, V.

2016-04-01

This paper presents an evolutionary battery impedance estimation method, which can be easily embedded in vehicles or nomad devices. The proposed method not only allows an accurate frequency impedance estimation, but also a tracking of its temporal evolution contrary to classical electrochemical impedance spectroscopy methods. Taking into account constraints of cost and complexity, we propose to use the existing electronics of current control to perform a frequency evolutionary estimation of the electrochemical impedance. The developed method uses a simple wideband input signal, and relies on a recursive local average of Fourier transforms. The averaging is controlled by a single parameter, managing a trade-off between tracking and estimation performance. This normalized parameter allows to correctly adapt the behavior of the proposed estimator to the variations of the impedance. The advantage of the proposed method is twofold: the method is easy to embed into a simple electronic circuit, and the battery impedance estimator is evolutionary. The ability of the method to monitor the impedance over time is demonstrated on a simulator, and on a real Lithium ion battery, on which a repeatability study is carried out. The experiments reveal good tracking results, and estimation performance as accurate as the usual laboratory approaches.

Robust design of biological circuits: evolutionary systems biology approach.

PubMed

Chen, Bor-Sen; Hsu, Chih-Yuan; Liou, Jing-Jia

2011-01-01

Artificial gene circuits have been proposed to be embedded into microbial cells that function as switches, timers, oscillators, and the Boolean logic gates. Building more complex systems from these basic gene circuit components is one key advance for biologic circuit design and synthetic biology. However, the behavior of bioengineered gene circuits remains unstable and uncertain. In this study, a nonlinear stochastic system is proposed to model the biological systems with intrinsic parameter fluctuations and environmental molecular noise from the cellular context in the host cell. Based on evolutionary systems biology algorithm, the design parameters of target gene circuits can evolve to specific values in order to robustly track a desired biologic function in spite of intrinsic and environmental noise. The fitness function is selected to be inversely proportional to the tracking error so that the evolutionary biological circuit can achieve the optimal tracking mimicking the evolutionary process of a gene circuit. Finally, several design examples are given in silico with the Monte Carlo simulation to illustrate the design procedure and to confirm the robust performance of the proposed design method. The result shows that the designed gene circuits can robustly track desired behaviors with minimal errors even with nontrivial intrinsic and external noise.

Tracking motions from satellite water vapor imagery: Quantitative applications to hurricane track forecasting

NASA Technical Reports Server (NTRS)

Velden, Christopher; Nieman, Steve; Aberson, Sim; Franklin, James

1993-01-01

Water vapor imagery from GOES satellites has been available for over a decade. These data are used extensively, mainly in a qualitative mode, by forecasters in the United States (Weldon and Holmes, 1991). Some attempts have been made at quantifying the data by tracking features in time sequences of the imagery (Stewart et al., 1985; Hayden and Stewart, 1987). For a variety of reasons, applications of this approach have produced marginal results (Velden, 1990). Recently, METEOSAT-3 (M-3) was repositioned at 50W by the European Space Agency, in order to provide complete coverage of the Atlantic Ocean. Data from this satellite are being transmitted to the U.S. for operational use. Compared with the GOES satellite, the M-3 has a superior resolution and signal-to-noise ratio in its water vapor channel, which translates into improved automated tracking capabilities. During a period in 1992 which included the Atlantic hurricane season, water vapor tracking algorithms were applied to the M-3 data in order to evaluate the coverage, accuracy and model impact of the derived vectors. Data sets were produced during several tropical cyclone cases, including Hurricane Andrew. In this paper, the M-3 water vapor wind sets are assessed, and their impact on a hurricane track forecast model is examined.

The role of vestibular and support-tactile-proprioceptive inputs in visual-manual tracking

NASA Astrophysics Data System (ADS)

Kornilova, Ludmila; Naumov, Ivan; Glukhikh, Dmitriy; Khabarova, Ekaterina; Pavlova, Aleksandra; Ekimovskiy, Georgiy; Sagalovitch, Viktor; Smirnov, Yuriy; Kozlovskaya, Inesa

Sensorimotor disorders in weightlessness are caused by changes of functioning of gravity-dependent systems, first of all - vestibular and support. The question arises, what’s the role and the specific contribution of the support afferentation in the development of observed disorders. To determine the role and effects of vestibular, support, tactile and proprioceptive afferentation on characteristics of visual-manual tracking (VMT) we conducted a comparative analysis of the data obtained after prolonged spaceflight and in a model of weightlessness - horizontal “dry” immersion. Altogether we examined 16 Russian cosmonauts before and after prolonged spaceflights (129-215 days) and 30 subjects who stayed in immersion bath for 5-7 days to evaluate the state of the vestibular function (VF) using videooculography and characteristics of the visual-manual tracking (VMT) using electrooculography & joystick with biological visual feedback. Evaluation of the VF has shown that both after immersion and after prolonged spaceflight there were significant decrease of the static torsional otolith-cervical-ocular reflex (OCOR) and simultaneous significant increase of the dynamic vestibular-cervical-ocular reactions (VCOR) with a revealed negative correlation between parameters of the otoliths and canals reactions, as well as significant changes in accuracy of perception of the subjective visual vertical which correlated with changes in OCOR. Analyze of the VMT has shown that significant disorders of the visual tracking (VT) occurred from the beginning of the immersion up to 3-4 day after while in cosmonauts similar but much more pronounced oculomotor disorders and significant changes from the baseline were observed up to R+9 day postflight. Significant changes of the manual tracking (MT) were revealed only for gain and occurred on 1 and 3 days in immersion while after spaceflight such changes were observed up to R+5 day postflight. We found correlation between characteristics of the VT and MT, between characteristics of the VF and VT and no correlation between VF and MT. It was found that removal of the support and minimization of the proprioceptive afferentation has a greater impact upon accuracy of the VT then accuracy of the MT. Hand tracking accuracy was higher than the eyes for all subjects. The hand’ motor coordination was more stable to changes in support-proprioceptive afferentation then visual tracking. The observed changes in and after immersion are similar but less pronounced with changes observed on cosmonauts after prolonged spaceflight. Keywords: visual-manual tracking, vestibular function, weightlessness, immersion.

Harmonic Characteristics of Rectifier Substations and Their Impact on Audio Frequency Track Circuits

DOT National Transportation Integrated Search

1982-05-01

This report describes the basic operation of substation rectifier equipment and the modes of possible interference with audio frequency track circuits used for train detection, cab signalling, and vehicle speed control. It also includes methods of es...

Neuro-Analogical Gate Tuning of Trajectory Data Fusion for a Mecanum-Wheeled Special Needs Chair

PubMed Central

ElSaharty, M. A.; zakzouk, Ezz Eldin

2017-01-01

Trajectory tracking of mobile wheeled chairs using internal shaft encoder and inertia measurement unit(IMU), exhibits several complications and accumulated errors in the tracking process due to wheel slippage, offset drift and integration approximations. These errors can be realized when comparing localization results from such sensors with a camera tracking system. In long trajectory tracking, such errors can accumulate and result in significant deviations which make data from these sensors unreliable for tracking. Meanwhile the utilization of an external camera tracking system is not always a feasible solution depending on the implementation environment. This paper presents a novel sensor fusion method that combines the measurements of internal sensors to accurately predict the location of the wheeled chair in an environment. The method introduces a new analogical OR gate structured with tuned parameters using multi-layer feedforward neural network denoted as “Neuro-Analogical Gate” (NAG). The resulting system minimize any deviation error caused by the sensors, thus accurately tracking the wheeled chair location without the requirement of an external camera tracking system. The fusion methodology has been tested with a prototype Mecanum wheel-based chair, and significant improvement over tracking response, error and performance has been observed. PMID:28045973

Evaluation of the clinical efficacy of the PeTrack motion tracking system for respiratory gating in cardiac PET imaging

NASA Astrophysics Data System (ADS)

Manwell, Spencer; Chamberland, Marc J. P.; Klein, Ran; Xu, Tong; deKemp, Robert

2017-03-01

Respiratory gating is a common technique used to compensate for patient breathing motion and decrease the prevalence of image artifacts that can impact diagnoses. In this study a new data-driven respiratory gating method (PeTrack) was compared with a conventional optical tracking system. The performance of respiratory gating of the two systems was evaluated by comparing the number of respiratory triggers, patient breathing intervals and gross heart motion as measured in the respiratory-gated image reconstructions of rubidium-82 cardiac PET scans in test and control groups consisting of 15 and 8 scans, respectively. We found evidence suggesting that PeTrack is a robust patient motion tracking system that can be used to retrospectively assess patient motion in the event of failure of the conventional optical tracking system.

Synergy of stereo cloud top height and ORAC optimal estimation cloud retrieval: evaluation and application to AATSR

NASA Astrophysics Data System (ADS)

Fisher, Daniel; Poulsen, Caroline A.; Thomas, Gareth E.; Muller, Jan-Peter

2016-03-01

In this paper we evaluate the impact on the cloud parameter retrievals of the ORAC (Optimal Retrieval of Aerosol and Cloud) algorithm following the inclusion of stereo-derived cloud top heights as a priori information. This is performed in a mathematically rigorous way using the ORAC optimal estimation retrieval framework, which includes the facility to use such independent a priori information. Key to the use of a priori information is a characterisation of their associated uncertainty. This paper demonstrates the improvements that are possible using this approach and also considers their impact on the microphysical cloud parameters retrieved. The Along-Track Scanning Radiometer (AATSR) instrument has two views and three thermal channels, so it is well placed to demonstrate the synergy of the two techniques. The stereo retrieval is able to improve the accuracy of the retrieved cloud top height when compared to collocated Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), particularly in the presence of boundary layer inversions and high clouds. The impact of the stereo a priori information on the microphysical cloud properties of cloud optical thickness (COT) and effective radius (RE) was evaluated and generally found to be very small for single-layer clouds conditions over open water (mean RE differences of 2.2 (±5.9) microns and mean COD differences of 0.5 (±1.8) for single-layer ice clouds over open water at elevations of above 9 km, which are most strongly affected by the inclusion of the a priori).

Infrared measurement and composite tracking algorithm for air-breathing hypersonic vehicles

NASA Astrophysics Data System (ADS)

Zhang, Zhao; Gao, Changsheng; Jing, Wuxing

2018-03-01

Air-breathing hypersonic vehicles have capabilities of hypersonic speed and strong maneuvering, and thus pose a significant challenge to conventional tracking methodologies. To achieve desirable tracking performance for hypersonic targets, this paper investigates the problems related to measurement model design and tracking model mismatching. First, owing to the severe aerothermal effect of hypersonic motion, an infrared measurement model in near space is designed and analyzed based on target infrared radiation and an atmospheric model. Second, using information from infrared sensors, a composite tracking algorithm is proposed via a combination of the interactive multiple models (IMM) algorithm, fitting dynamics model, and strong tracking filter. During the procedure, the IMMs algorithm generates tracking data to establish a fitting dynamics model of the target. Then, the strong tracking unscented Kalman filter is employed to estimate the target states for suppressing the impact of target maneuvers. Simulations are performed to verify the feasibility of the presented composite tracking algorithm. The results demonstrate that the designed infrared measurement model effectively and continuously observes hypersonic vehicles, and the proposed composite tracking algorithm accurately and stably tracks these targets.

Experimental observations of low-velocity collisional systems

NASA Astrophysics Data System (ADS)

Jorges, Jeffery; Dove, Adrienne; Colwell, Joshua

Low-velocity collisions in systems of centimeter-sized objects may result in particle growth by accretion, rebounding, or erosive processes that result in the production of additional smaller particles. Numerical simulations of these systems are limited by a need to understand the collisional parameters governing the outcomes of these collisions over a range of conditions. Here, we present the results from laboratory experiments designed to explore low-velocity collisions by conducting experiments in a vacuum chamber in our 0.8-sec drop tower apparatus. These experiments utilize a variety of impacting spheres, including glass, Teflon, aluminum, stainless steel, and brass. These spheres are either used in their natural state or are ``mantled'' - coated with a few-mm thick layer of a cohesive powder. A high-speed, high-resolution video camera is used to record the motion of the colliding bodies. These videos are then processed and we track the particles to determine impactor speeds before and after collision and the collisional outcome. We determine how the coefficient of restitution varies as a function of material type, morphology, and impact velocity. For impact velocities in the range from about 20-100 cm/s we observe that mantling of particles has the most significant effect, reducing the coefficients of restitution.

Measuring saliency in images: which experimental parameters for the assessment of image quality?

NASA Astrophysics Data System (ADS)

Fredembach, Clement; Woolfe, Geoff; Wang, Jue

2012-01-01

Predicting which areas of an image are perceptually salient or attended to has become an essential pre-requisite of many computer vision applications. Because observers are notoriously unreliable in remembering where they look a posteriori, and because asking where they look while observing the image necessarily in uences the results, ground truth about saliency and visual attention has to be obtained by gaze tracking methods. From the early work of Buswell and Yarbus to the most recent forays in computer vision there has been, perhaps unfortunately, little agreement on standardisation of eye tracking protocols for measuring visual attention. As the number of parameters involved in experimental methodology can be large, their individual in uence on the nal results is not well understood. Consequently, the performance of saliency algorithms, when assessed by correlation techniques, varies greatly across the literature. In this paper, we concern ourselves with the problem of image quality. Specically: where people look when judging images. We show that in this case, the performance gap between existing saliency prediction algorithms and experimental results is signicantly larger than otherwise reported. To understand this discrepancy, we rst devise an experimental protocol that is adapted to the task of measuring image quality. In a second step, we compare our experimental parameters with the ones of existing methods and show that a lot of the variability can directly be ascribed to these dierences in experimental methodology and choice of variables. In particular, the choice of a task, e.g., judging image quality vs. free viewing, has a great impact on measured saliency maps, suggesting that even for a mildly cognitive task, ground truth obtained by free viewing does not adapt well. Careful analysis of the prior art also reveals that systematic bias can occur depending on instrumental calibration and the choice of test images. We conclude this work by proposing a set of parameters, tasks and images that can be used to compare the various saliency prediction methods in a manner that is meaningful for image quality assessment.

Evaluating the Community Land Model in a pine stand with shading manipulations and 13CO 2 labeling

DOE PAGES

Mao, Jiafu; Ricciuto, Daniel M.; Thornton, Peter E.; ...

2016-02-03

Carbon partitioning and flow through ecosystems regulates land surface atmosphere CO 2 exchange and thus is a key, albeit uncertain component of mechanistic models. The Partitioning in Trees and Soil (PiTS) experiment-model project tracked C partitioning through a young Pinus taeda stand following pulse-labeling with 13CO 2 and two levels of shading. The field component of this project provided process-oriented data that was used to evaluate and improve terrestrial biosphere model simulations of rapid shifts in carbon partitioning and hydrological dynamics under varying environmental conditions. Here we tested the performance of the Community Land Model version 4 (CLM4) in capturingmore » short-term carbon and water dynamics in relation to manipulative shading treatments, and the timing and magnitude of carbon fluxes through various compartments of the ecosystem. To constrain CLM4 to closely simulate pretreatment conditions, we calibrated select model parameters with the pretreatment observational data. Compared to CLM4 simulations with default parameters, CLM4 with calibrated model parameters was better able to simulate pretreatment vegetation carbon pools, light response curves, and other initial states and fluxes of carbon and water. Over a 3-week treatment period, the calibrated CLM4 generally reproduced the impacts of shading on average soil moisture at 15-95 cm depth, transpiration, relative change in stem carbon, and soil CO 2 efflux rate, although some discrepancies in the estimation of magnitudes and temporal evolutions existed. CLM4, however, was not able to track the progression of the 13CO 2 label from the atmosphere through foliage, phloem, roots or surface soil CO 2 efflux, even when optimized model parameters were used. This model bias arises, in part, from the lack of a short-term non-structural carbohydrate storage pool and progressive timing of within-plant transport, thus indicating a need for future work to improve the allocation routines in CLM4. Overall, these types of detailed evaluations of CLM4, paired with intensive field manipulations, can help to identify model strengths and weaknesses, model uncertainties, and additional observations necessary for future model development.« less

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Resistance of equine tibiae and radii to side impact loads.

PubMed

Piskoty, G; Jäggin, S; Michel, S A; Weisse, B; Terrasi, G P; Fürst, A

2012-11-01

There are no detailed studies describing the resistance of equine tibiae and radii to side impact loads, such as a horse kick and a better understanding of the general long bone impact behavioural model is required. To quantify the typical impact energy required to fracture or fissure an equine long bone, as well as to determine the range and time course of the impact force under conditions similar to that of a horse kick. Seventy-two equine tibiae and radii were investigated using a drop impact tester. The prepared bones were preloaded with an axial force of 2.5 kN and were then hit in the middle of the medial side. The impact velocity of the metal impactor, weighting 2 kg, was varied within the range of 6-11 m/s. The impact process was captured with a high-speed camera from the craniomedial side of the bone. The videos were used both for slow-motion observation of the process and for quantifying physical parameters, such as peak force via offline video tracking and subsequent numerical derivation of the 'position vs. time' function for the impactor. The macroscopic appearance of the resultant bone injuries was found to be similar to those produced by authentic horse kicks, indicating a successful simulation of the real load case. The impact behaviours of tibiae and radii do not differ considerably in terms of the investigated general characteristics. Peak force occurred between 0.15-0.30 ms after the start of the impact. The maximum contact force correlated with the 1.45-power of the impact velocity if no fracture occurred (F(max) ≈ 0.926 · v(i) (1.45) ). Peak force scatter was considerably larger within the fractured sub-group compared with fissured bones. The peak force for fracture tended to lie below the aforementioned function, within the range of F(max) = 11-23 kN ('fracture load'). The impact energy required to fracture a bone varied from 40-90 J. The video-based measuring method allowed quantifying of the most relevant physical parameters, such as contact force and energy balance. The results obtained should help with the development of bone implants and guards, supporting theoretical studies, and in the evaluation of bone injuries. © 2012 EVJ Ltd.

The heat rate index indicator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lasasso, M.; Runyan, B.; Napoli, J.

1995-06-01

This paper describes a method of tracking unit performance through the use of a reference number called the Heat Rate Index Indicator. The ABB Power Plant Controls OTIS performance monitor is used to determine when steady load conditions exist and then to collect controllable and equipment loss data which significantly impact thermal efficiency. By comparing these loss parameters to those found during the previous heat balance, it is possible to develop a new adjusted heat rate curve. These impacts on heat rate are used to changes the shape of the tested heat rate curve by the appropriate percentages over amore » specified load range. Mathcad is used to determine the Heat Rate Index by integrating for the areas beneath the adjusted heat rate curve and a heat rate curve that represents the unit`s ideal heat rate curve is the Heat Rate Index. An index of 1.0 indicates that the unit is operating at an ideal efficiency, while an index of less than 1.0 indicates that the unit is operating at less than ideal conditions. A one per cent change in the Heat Rate Index is equivalent to a one percent change in heat rate. The new shape of the adjusted heat rate curve and the individual curves generated from the controllable and equipment loss parameters are useful for determining performance problems in specific load ranges.« less

Robust adaptive tracking control for nonholonomic mobile manipulator with uncertainties.

PubMed

Peng, Jinzhu; Yu, Jie; Wang, Jie

2014-07-01

In this paper, mobile manipulator is divided into two subsystems, that is, nonholonomic mobile platform subsystem and holonomic manipulator subsystem. First, the kinematic controller of the mobile platform is derived to obtain a desired velocity. Second, regarding the coupling between the two subsystems as disturbances, Lyapunov functions of the two subsystems are designed respectively. Third, a robust adaptive tracking controller is proposed to deal with the unknown upper bounds of parameter uncertainties and disturbances. According to the Lyapunov stability theory, the derived robust adaptive controller guarantees global stability of the closed-loop system, and the tracking errors and adaptive coefficient errors are all bounded. Finally, simulation results show that the proposed robust adaptive tracking controller for nonholonomic mobile manipulator is effective and has good tracking capacity. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Perioperative strategy in colonic surgery; LAparoscopy and/or FAst track multimodal management versus standard care (LAFA trial)

PubMed Central

Wind, Jan; Hofland, Jan; Preckel, Benedikt; Hollmann, Markus W; Bossuyt, Patrick MM; Gouma, Dirk J; van Berge Henegouwen, Mark I; Fuhring, Jan Willem; Dejong, Cornelis HC; van Dam, Ronald M; Cuesta, Miguel A; Noordhuis, Astrid; de Jong, Dick; van Zalingen, Edith; Engel, Alexander F; Goei, T Hauwy; de Stoppelaar, I Erica; van Tets, Willem F; van Wagensveld, Bart A; Swart, Annemiek; van den Elsen, Maarten JLJ; Gerhards, Michael F; de Wit, Laurens Th; Siepel, Muriel AM; van Geloven, Anna AW; Juttmann, Jan-Willem; Clevers, Wilfred; Bemelman, Willem A

2006-01-01

Background Recent developments in large bowel surgery are the introduction of laparoscopic surgery and the implementation of multimodal fast track recovery programs. Both focus on a faster recovery and shorter hospital stay. The randomized controlled multicenter LAFA-trial (LAparoscopy and/or FAst track multimodal management versus standard care) was conceived to determine whether laparoscopic surgery, fast track perioperative care or a combination of both is to be preferred over open surgery with standard care in patients having segmental colectomy for malignant disease. Methods/design The LAFA-trial is a double blinded, multicenter trial with a 2 × 2 balanced factorial design. Patients eligible for segmental colectomy for malignant colorectal disease i.e. right and left colectomy and anterior resection will be randomized to either open or laparoscopic colectomy, and to either standard care or the fast track program. This factorial design produces four treatment groups; open colectomy with standard care (a), open colectomy with fast track program (b), laparoscopic colectomy with standard care (c), and laparoscopic surgery with fast track program (d). Primary outcome parameter is postoperative hospital length of stay including readmission within 30 days. Secondary outcome parameters are quality of life two and four weeks after surgery, overall hospital costs, morbidity, patient satisfaction and readmission rate. Based on a mean postoperative hospital stay of 9 +/- 2.5 days a group size of 400 patients (100 each arm) can reliably detect a minimum difference of 1 day between the four arms (alfa = 0.95, beta = 0.8). With 100 patients in each arm a difference of 10% in subscales of the Short Form 36 (SF-36) questionnaire and social functioning can be detected. Discussion The LAFA-trial is a randomized controlled multicenter trial that will provide evidence on the merits of fast track perioperative care and laparoscopic colorectal surgery in patients having segmental colectomy for malignant disease. PMID:17134506

Adaptive robust motion trajectory tracking control of pneumatic cylinders with LuGre model-based friction compensation

NASA Astrophysics Data System (ADS)

Meng, Deyuan; Tao, Guoliang; Liu, Hao; Zhu, Xiaocong

2014-07-01

Friction compensation is particularly important for motion trajectory tracking control of pneumatic cylinders at low speed movement. However, most of the existing model-based friction compensation schemes use simple classical models, which are not enough to address applications with high-accuracy position requirements. Furthermore, the friction force in the cylinder is time-varying, and there exist rather severe unmodelled dynamics and unknown disturbances in the pneumatic system. To deal with these problems effectively, an adaptive robust controller with LuGre model-based dynamic friction compensation is constructed. The proposed controller employs on-line recursive least squares estimation (RLSE) to reduce the extent of parametric uncertainties, and utilizes the sliding mode control method to attenuate the effects of parameter estimation errors, unmodelled dynamics and disturbances. In addition, in order to realize LuGre model-based friction compensation, the modified dual-observer structure for estimating immeasurable friction internal state is developed. Therefore, a prescribed motion tracking transient performance and final tracking accuracy can be guaranteed. Since the system model uncertainties are unmatched, the recursive backstepping design technology is applied. In order to solve the conflicts between the sliding mode control design and the adaptive control design, the projection mapping is used to condition the RLSE algorithm so that the parameter estimates are kept within a known bounded convex set. Finally, the proposed controller is tested for tracking sinusoidal trajectories and smooth square trajectory under different loads and sudden disturbance. The testing results demonstrate that the achievable performance of the proposed controller is excellent and is much better than most other studies in literature. Especially when a 0.5 Hz sinusoidal trajectory is tracked, the maximum tracking error is 0.96 mm and the average tracking error is 0.45 mm. This paper constructs an adaptive robust controller which can compensate the friction force in the cylinder.

Visual attention is required for multiple object tracking.

PubMed

Tran, Annie; Hoffman, James E

2016-12-01

In the multiple object tracking task, participants attempt to keep track of a moving set of target objects embedded in an identical set of moving distractors. Depending on several display parameters, observers are usually only able to accurately track 3 to 4 objects. Various proposals attribute this limit to a fixed number of discrete indexes (Pylyshyn, 1989), limits in visual attention (Cavanagh & Alvarez, 2005), or "architectural limits" in visual cortical areas (Franconeri, 2013). The present set of experiments examined the specific role of visual attention in tracking using a dual-task methodology in which participants tracked objects while identifying letter probes appearing on the tracked objects and distractors. As predicted by the visual attention model, probe identification was faster and/or more accurate when probes appeared on tracked objects. This was the case even when probes were more than twice as likely to appear on distractors suggesting that some minimum amount of attention is required to maintain accurate tracking performance. When the need to protect tracking accuracy was relaxed, participants were able to allocate more attention to distractors when probes were likely to appear there but only at the expense of large reductions in tracking accuracy. A final experiment showed that people attend to tracked objects even when letters appearing on them are task-irrelevant, suggesting that allocation of attention to tracked objects is an obligatory process. These results support the claim that visual attention is required for tracking objects. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Full-Scale Passive Earth Entry Vehicle Landing Tests: Methods and Measurements

NASA Technical Reports Server (NTRS)

Littell, Justin D.; Kellas, Sotiris

2018-01-01

During the summer of 2016, a series of drop tests were conducted on two passive earth entry vehicle (EEV) test articles at the Utah Test and Training Range (UTTR). The tests were conducted to evaluate the structural integrity of a realistic EEV vehicle under anticipated landing loads. The test vehicles were lifted to an altitude of approximately 400m via a helicopter and released via release hook into a predesignated 61 m landing zone. Onboard accelerometers were capable of measuring vehicle free flight and impact loads. High-speed cameras on the ground tracked the free-falling vehicles and data was used to calculate critical impact parameters during the final seconds of flight. Additional sets of high definition and ultra-high definition cameras were able to supplement the high-speed data by capturing the release and free flight of the test articles. Three tests were successfully completed and showed that the passive vehicle design was able to withstand the impact loads from nominal and off-nominal impacts at landing velocities of approximately 29 m/s. Two out of three test resulted in off-nominal impacts due to a combination of high winds at altitude and the method used to suspend the vehicle from the helicopter. Both the video and acceleration data captured is examined and discussed. Finally, recommendations for improved release and instrumentation methods are presented.

Implementation of an Open-Scenario, Long-Term Space Debris Simulation Approach

NASA Technical Reports Server (NTRS)

Nelson, Bron; Yang Yang, Fan; Carlino, Roberto; Dono Perez, Andres; Faber, Nicolas; Henze, Chris; Karacalioglu, Arif Goktug; O'Toole, Conor; Swenson, Jason; Stupl, Jan

2015-01-01

This paper provides a status update on the implementation of a flexible, long-term space debris simulation approach. The motivation is to build a tool that can assess the long-term impact of various options for debris-remediation, including the LightForce space debris collision avoidance concept that diverts objects using photon pressure [9]. State-of-the-art simulation approaches that assess the long-term development of the debris environment use either completely statistical approaches, or they rely on large time steps on the order of several days if they simulate the positions of single objects over time. They cannot be easily adapted to investigate the impact of specific collision avoidance schemes or de-orbit schemes, because the efficiency of a collision avoidance maneuver can depend on various input parameters, including ground station positions and orbital and physical parameters of the objects involved in close encounters (conjunctions). Furthermore, maneuvers take place on timescales much smaller than days. For example, LightForce only changes the orbit of a certain object (aiming to reduce the probability of collision), but it does not remove entire objects or groups of objects. In the same sense, it is also not straightforward to compare specific de-orbit methods in regard to potential collision risks during a de-orbit maneuver. To gain flexibility in assessing interactions with objects, we implement a simulation that includes every tracked space object in Low Earth Orbit (LEO) and propagates all objects with high precision and variable time-steps as small as one second. It allows the assessment of the (potential) impact of physical or orbital changes to any object. The final goal is to employ a Monte Carlo approach to assess the debris evolution during the simulation time-frame of 100 years and to compare a baseline scenario to debris remediation scenarios or other scenarios of interest. To populate the initial simulation, we use the entire space-track object catalog in LEO. We then use a high precision propagator to propagate all objects over the entire simulation duration. If collisions are detected, the appropriate number of debris objects are created and inserted into the simulation framework. Depending on the scenario, further objects, e.g. due to new launches, can be added. At the end of the simulation, the total number of objects above a cut-off size and the number of detected collisions provide benchmark parameters for the comparison between scenarios. The simulation approach is computationally intensive as it involves tens of thousands of objects; hence we use a highly parallel approach employing up to a thousand cores on the NASA Pleiades supercomputer for a single run. This paper describes our simulation approach, the status of its implementation, the approach to developing scenarios and examples of first test runs.

Statistical and Multifractal Evaluation of Soil Compaction in a Vineyard

NASA Astrophysics Data System (ADS)

Marinho, M.; Raposo, J. R.; Mirás Avalos, J. M.; Paz González, A.

2012-04-01

One of the detrimental effects caused by agricultural machines is soil compaction, which can be defined by an increase in soil bulk density. Soil compaction often has a negative impact on plant growth, since it reduces the macroporosity and soil permeability and increases resistance to penetration. Our research explored the effect of the agricultural machinery on soil when trafficking through a vineyard at a small spatial scale, based on the evaluation of the soil compaction status. The objectives of this study were: i) to quantify soil bulk density along transects following wine row, wheel track and outside track, and, ii) to characterize the variability of the bulk density along these transects using multifractal analysis. The field work was conducted at the experimental farm of EVEGA (Viticulture and Enology Centre of Galicia) located in Ponte San Clodio, Leiro, Orense, Spain. Three parallel transects were marked on positions with contrasting machine traffic effects, i.e. vine row, wheel-track and outside-track. Undisturbed samples were collected in 16 points of each transect, spaced 0.50 m apart, for bulk density determination using the cylinder method. Samples were taken in autumn 2011, after grape harvest. Since soil between vine rows was tilled and homogenized beginning spring 2011, cumulative effects of traffic during the vine growth period could be evaluated. The distribution patterns of soil bulk density were characterized by multifractal analysis carried out by the method of moments. Multifractality was assessed by several indexes derived from the mass exponent, τq, the generalized dimension, Dq, and the singularity spectrum, f(α), curves. Mean soil bulk density values determined for vine row, outside-track and wheel-track transects were 1.212 kg dm-3, 1.259 kg dm-3and 1.582 kg dm-3, respectively. The respective coefficients of variation (CV) for these three transects were 7.76%, 4.82% and 2.03%. Therefore mean bulk density under wheel-track was 30.5% higher than along the vine row. Vine row and outside-track positions showed not significant differences between means. The bulk density of the wheel-track transect also showed the lowest CV. The multifractal spectra of the three transects were asymmetric curves, rather short toward the left and much longer toward the right. The width of the right deviating shaped multifractal spectra was ranked as: wine row > outside-track ≈ wheel-track. Entropy dimension, D1, was 0.998, 0.992 and 0.992 for vine row, outside-track and track transects, respectively. These results show different patterns of variability of bulk density for parallel transects. They also suggest that multifractal parameters may be useful in assessing the variability of other soil properties such as soil particle density, soil porosity or soil water content, at different spatial scales as well. Acknowledgments. This work was funded in part by Spanish Ministry of Science and Innovation (MICINN) in the frame of project CGL2009-13700-C02. Financial support from CAPES/GOV., Brazil, is also acknowledged by Prof. M. Marinho.

A statistical survey of heat input parameters into the cusp thermosphere

NASA Astrophysics Data System (ADS)

Moen, J. I.; Skjaeveland, A.; Carlson, H. C.

2017-12-01

Based on three winters of observational data, we present those ionosphere parameters deemed most critical to realistic space weather ionosphere and thermosphere representation and prediction, in regions impacted by variability in the cusp. The CHAMP spacecraft revealed large variability in cusp thermosphere densities, measuring frequent satellite drag enhancements, up to doublings. The community recognizes a clear need for more realistic representation of plasma flows and electron densities near the cusp. Existing average-value models produce order of magnitude errors in these parameters, resulting in large under estimations of predicted drag. We fill this knowledge gap with statistics-based specification of these key parameters over their range of observed values. The EISCAT Svalbard Radar (ESR) tracks plasma flow Vi , electron density Ne, and electron, ion temperatures Te, Ti , with consecutive 2-3 minute windshield-wipe scans of 1000x500 km areas. This allows mapping the maximum Ti of a large area within or near the cusp with high temporal resolution. In magnetic field-aligned mode the radar can measure high-resolution profiles of these plasma parameters. By deriving statistics for Ne and Ti , we enable derivation of thermosphere heating deposition under background and frictional-drag-dominated magnetic reconnection conditions. We separate our Ne and Ti profiles into quiescent and enhanced states, which are not closely correlated due to the spatial structure of the reconnection foot point. Use of our data-based parameter inputs can make order of magnitude corrections to input data driving thermosphere models, enabling removal of previous two fold drag errors.

AIRS Impact on the Analysis and Forecast Track of Tropical Cyclone Nargis in a Global Data Assimilation and Forecasting System

NASA Technical Reports Server (NTRS)

Reale, O.; Lau, W.K.; Susskind, J.; Brin, E.; Liu, E.; Riishojgaard, L. P.; Rosenburg, R.; Fuentes, M.

2009-01-01

Tropical cyclones in the northern Indian Ocean pose serious challenges to operational weather forecasting systems, partly due to their shorter lifespan and more erratic track, compared to those in the Atlantic and the Pacific. Moreover, the automated analyses of cyclones over the northern Indian Ocean, produced by operational global data assimilation systems (DASs), are generally of inferior quality than in other basins. In this work it is shown that the assimilation of Atmospheric Infrared Sounder (AIRS) temperature retrievals under partial cloudy conditions can significantly impact the representation of the cyclone Nargis (which caused devastating loss of life in Myanmar in May 2008) in a global DAS. Forecasts produced from these improved analyses by a global model produce substantially smaller track errors. The impact of the assimilation of clear-sky radiances on the same DAS and forecasting system is positive, but smaller than the one obtained by ingestion of AIRS retrievals, possibly due to poorer coverage.

Splitting attention reduces temporal resolution from 7 Hz for tracking one object to <3 Hz when tracking three.

PubMed

Holcombe, Alex O; Chen, Wei-Ying

2013-01-09

Overall performance when tracking moving targets is known to be poorer for larger numbers of targets, but the specific effect on tracking's temporal resolution has never been investigated. We document a broad range of display parameters for which visual tracking is limited by temporal frequency (the interval between when a target is at each location and a distracter moves in and replaces it) rather than by object speed. We tested tracking of one, two, and three moving targets while the eyes remained fixed. Variation of the number of distracters and their speed revealed both speed limits and temporal frequency limits on tracking. The temporal frequency limit fell from 7 Hz with one target to 4 Hz with two targets and 2.6 Hz with three targets. The large size of this performance decrease implies that in the two-target condition participants would have done better by tracking only one of the two targets and ignoring the other. These effects are predicted by serial models involving a single tracking focus that must switch among the targets, sampling the position of only one target at a time. If parallel processing theories are to explain why dividing the tracking resource reduces temporal resolution so markedly, supplemental assumptions will be required.

Capturing and Displaying Uncertainty in the Common Tactical/Environmental Picture

DTIC Science & Technology

2003-09-30

multistatic active detection, and incorporated this characterization into a Bayesian track - before - detect system called, the Likelihood Ratio Tracker (LRT...prediction uncertainty in a track before detect system for multistatic active sonar. The approach has worked well on limited simulation data. IMPACT

Tracking long-distance migration to assess marine pollution impact

PubMed Central

Montevecchi, William; Fifield, David; Burke, Chantelle; Garthe, Stefan; Hedd, April; Rail, Jean-François; Robertson, Gregory

2012-01-01

Animal tracking provides new means to assess far-reaching environmental impacts. In the aftermath of the Deepwater Horizon explosion in the Gulf of Mexico, a long-distance migrant, the northern gannet (Morus bassanus) suffered the highest oiling among beach-wrecked birds recovered. Analysis of bird-borne tracking data indicated that 25 per cent of their North American population from multiple colonies in eastern Canada migrated to the pollution zone. Findings contrasted sharply with available mark-recapture (band recovery) data. The timing of movement into and out of the Gulf indicates that immature birds would have absorbed most oil-induced mortality. Consequently, one of two outcomes is likely: either a lagged (likely difficult to assess) population decrease, or an undetectable population response buffered by age-related life-history adaptations. Tracking research is especially useful when little information on animal distributions in pollution zones is available, as is the case in the Gulf of Mexico. Ongoing research highlights current risks and conservation concerns. PMID:22012949

Sedimentation patterns caused by scallop dredging in a physically dynamic environment.

PubMed

Dale, A C; Boulcott, P; Sherwin, T J

2011-11-01

Scallop dredging grounds in the Firth of Lorn, western Scotland, are juxtaposed with rocky reef habitats raising concerns that reef communities may be impacted by sediment disturbed by nearby scallop dredging. A particle-tracking model of sediment transport and settling is applied at two scales. In the near-field, a suspension of typical sand/gravel-dominated bed sediment is subjected to a steady current across the dredge track. In the far-field, silt particles, which may persist in suspension for multiple tidal cycles, are tracked in the context of a regional model of tidally-driven flow. The principal sedimentary risk to reef habitats is predicted to come from settling sand particles when dredge tracks approach within tens of metres of a reef. The cumulative effect of dredging at the relatively low intensities recorded in this region is not expected to have a significant long-term impact on suspended silt concentrations and settlement in this highly dispersive environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

Synthesis of an optoelectronic system for tracking (OEST) the information track of the optical record carrier based on the acceleration control principle

NASA Astrophysics Data System (ADS)

Zalogin, Stanislav M.; Zalogin, M. S.

1997-02-01

The problem for construction of control algorithm in OEST the information track of the optical record carrier the realization of which is based on the use of accelerations is considered. Such control algorithms render the designed system the properties of adaptability, feeble sensitivity to the system parameter change and the action of disturbing forces what gives known advantages to information carriers with such system under operation in hard climate conditions as well as at maladjustment, workpieces wear and change of friction in the system. In the paper are investigated dynamic characteristics of a closed OEST, it is shown, that the designed stable system with given quality indices is a high-precision one. The validated recommendations as to design of control algorithms parameters are confirmed by results of mathematical simulation of controlled processes. The proposed methods for OEST synthesis on the basis of the control acceleration principle can be recommended for the use at industrial production of optical information record carriers.

Short-Arc Analysis of Intersatellite Tracking Data in a Gravity Mapping Mission

NASA Technical Reports Server (NTRS)

Rowlands, David D.; Ray, Richard D.; Chinn, Douglas S.; Lemoine, Frank G.; Smith, David E. (Technical Monitor)

2001-01-01

A technique for the analysis of low-low intersatellite range-rate data in a gravity mapping mission is explored. The technique is based on standard tracking data analysis for orbit determination but uses a spherical coordinate representation of the 12 epoch state parameters describing the baseline between the two satellites. This representation of the state parameters is exploited to allow the intersatellite range-rate analysis to benefit from information provided by other tracking data types without large simultaneous multiple data type solutions. The technique appears especially valuable for estimating gravity from short arcs (e.g., less than 15 minutes) of data. Gravity recovery simulations which use short arcs are compared with those using arcs a day in length. For a high-inclination orbit, the short-arc analysis recovers low-order gravity coefficients remarkably well, although higher order terms, especially sectorial terms, are less accurate. Simulations suggest that either long or short arcs of GRACE data are likely to improve parts of the geopotential spectrum by orders of magnitude.

Sensitivity analysis of free vibration characteristics of an in situ railway concrete sleeper to variations of rail pad parameters

NASA Astrophysics Data System (ADS)

Kaewunruen, Sakdirat; Remennikov, Alex M.

2006-11-01

The vibration of in situ concrete sleepers in a railway track structure is a major factor causing cracking of prestressed concrete sleepers and excessive railway track maintenance cost. Not only does the ballast interact with the sleepers, but the rail pads also take part in affecting their free vibration characteristics. This paper presents a sensitivity analysis of free vibration behaviors of an in situ railway concrete sleeper (standard gauge sleeper), incorporating sleeper/ballast interaction, subjected to the variations of rail pad properties. Through finite element analysis, Timoshenko-beam and spring elements were used in the in situ railway concrete sleeper modeling. This model highlights the influence of rail pad parameters on the free vibration characteristics of in situ sleepers. In addition, information on the first five flexural vibration modes indicates the dynamic performance of railway track when using different types of rail pads, as it plays a vital role in the cracking deterioration of concrete sleepers.

A discrete-time adaptive control scheme for robot manipulators

NASA Technical Reports Server (NTRS)

Tarokh, M.

1990-01-01

A discrete-time model reference adaptive control scheme is developed for trajectory tracking of robot manipulators. The scheme utilizes feedback, feedforward, and auxiliary signals, obtained from joint angle measurement through simple expressions. Hyperstability theory is utilized to derive the adaptation laws for the controller gain matrices. It is shown that trajectory tracking is achieved despite gross robot parameter variation and uncertainties. The method offers considerable design flexibility and enables the designer to improve the performance of the control system by adjusting free design parameters. The discrete-time adaptation algorithm is extremely simple and is therefore suitable for real-time implementation. Simulations and experimental results are given to demonstrate the performance of the scheme.

Parameters Identification for Motorcycle Simulator's Platform Characterization

NASA Astrophysics Data System (ADS)

Nehaoua, L.; Arioui, H.

2008-06-01

This paper presents the dynamics modeling and parameters identification of a motorcycle simulator's platform. This model begins with some suppositions which consider that the leg dynamics can be neglected with respect to the mobile platform one. The objectif is to synthesis a simplified control scheme, adapted to driving simulation application, minimising dealys and without loss of tracking performance. Electronic system of platform actuation is described. It's based on a CAN BUS communication which offers a large transmission robustness and error handling. Despite some disadvanteges, we adapted a control solution which overcome these inconvenients and preserve the quality of tracking trajectory. A bref description of the simulator's platform is given and results are shown and justified according to our specifications.

A helmet mounted display to adapt the telerobotic environment to human vision

NASA Technical Reports Server (NTRS)

Tharp, Gregory; Liu, Andrew; Yamashita, Hitomi; Stark, Lawrence

1990-01-01

A Helmet Mounted Display system has been developed. It provides the capability to display stereo images with the viewpoint tied to subjects' head orientation. The type of display might be useful in a telerobotic environment provided the correct operating parameters are known. The effects of update frequency were tested using a 3D tracking task. The effects of blur were tested using both tracking and pick-and-place tasks. For both, researchers found that operator performance can be degraded if the correct parameters are not used. Researchers are also using the display to explore the use of head movements as part of gaze as subjects search their visual field for target objects.

The performance of a sampled data delay lock loop implemented with a Kalman loop filter

NASA Astrophysics Data System (ADS)

Eilts, H. S.

1980-01-01

The purpose of this study is to evaluate the steady-state and transient (lock-up) performance of a tracking loop implemented with a Kalman filter. Steady-state performance criteria are errors due to measurement noise (jitter) and Doppler errors due to motion of the tracking loop. Trade-offs exist between the two criteria such that increasing performance with respect to either one will cause performance decrease with respect to the other. It is shown that by carefully selecting filter parameters reasonable performance can be obtained for both criteria simultaneously. It is also shown that lock-up performance for the loop is acceptable when these parameters are used.

Hydrocarbon Contamination Decreases Mating Success in a Marine Planktonic Copepod

PubMed Central

Seuront, Laurent

2011-01-01

The mating behavior and the mating success of copepods rely on chemoreception to locate and track a sexual partner. However, the potential impact of the water-soluble fraction of hydrocarbons on these aspects of copepod reproduction has never been tested despite the widely acknowledged acute chemosensory abilities of copepods. I examined whether three concentrations of the water-soluble fraction of diesel oil (0.01%, 0.1% and 1%) impacts (i) the swimming behavior of both adult males and females of the widespread calanoid copepod Temora longcornis, and (ii) the ability of males to locate, track and mate with females. The three concentrations of the water-soluble fraction of diesel oil (WSF) significantly and non-significantly affect female and male swimming velocities, respectively. In contrast, both the complexity of male and female swimming paths significantly decreased with increasing WSF concentrations, hence suggesting a sex-specific sensitivity to WSF contaminated seawater. In addition, the three WSF concentrations impacted both T. longicornis mating behavior and mating success. Specifically, the ability of males to detect female pheromone trails, to accurately follow trails and to successfully track a female significantly decreased with increasing WSF concentrations. This led to a significant decrease in contact and capture rates from control to WSF contaminated seawater. These results indicate that hydrocarbon contamination of seawater decreases the ability of male copepods to detect and track a female, hence suggest an overall impact on population fitness and dynamics. PMID:22053187

Precision Positional Data of General Aviation Air Traffic in Terminal Air Space

NASA Technical Reports Server (NTRS)

Melson, W. E., Jr.; Parker, L. C.; Northam, A. M.; Singh, R. P.

1978-01-01

Three dimensional radar tracks of general aviation air traffic at three uncontrolled airports are considered. Contained are data which describe the position-time histories, other derived parameters, and reference data for the approximately 1200 tracks. All information was correlated such that the date, time, flight number, and runway number match the pattern type, aircraft type, wind, visibility, and cloud conditions.

Low Complexity Track Initialization and Fusion for Multi-Modal Sensor Networks

DTIC Science & Technology

2012-11-08

feature was demonstrated via the simulations. Aerospace 2011work further documents our investigation of multiple target tracking filters in...bounds that determine how well a sensor network can resolve and localize multiple targets as a function of the operating parameters such as sensor...probability density (PHD) filter for binary measurements using proximity sensors. 15. SUBJECT TERMS proximity sensors, PHD filter, multiple

Fuzzy adaptive strong tracking scaled unscented Kalman filter for initial alignment of large misalignment angles

NASA Astrophysics Data System (ADS)

Li, Jing; Song, Ningfang; Yang, Gongliu; Jiang, Rui

2016-07-01

In the initial alignment process of strapdown inertial navigation system (SINS), large misalignment angles always bring nonlinear problem, which can usually be processed using the scaled unscented Kalman filter (SUKF). In this paper, the problem of large misalignment angles in SINS alignment is further investigated, and the strong tracking scaled unscented Kalman filter (STSUKF) is proposed with fixed parameters to improve convergence speed, while these parameters are artificially constructed and uncertain in real application. To further improve the alignment stability and reduce the parameters selection, this paper proposes a fuzzy adaptive strategy combined with STSUKF (FUZZY-STSUKF). As a result, initial alignment scheme of large misalignment angles based on FUZZY-STSUKF is designed and verified by simulations and turntable experiment. The results show that the scheme improves the accuracy and convergence speed of SINS initial alignment compared with those based on SUKF and STSUKF.

An improved model of the Earth's gravitational field: GEM-T1

NASA Technical Reports Server (NTRS)

Marsh, J. G.; Lerch, F. J.; Christodoulidis, D. C.; Putney, B. H.; Felsentreger, T. L.; Sanchez, B. V.; Smith, D. E.; Klosko, S. M.; Martin, T. V.; Pavlis, E. C.

1987-01-01

Goddard Earth Model T1 (GEM-T1), which was developed from an analysis of direct satellite tracking observations, is the first in a new series of such models. GEM-T1 is complete to degree and order 36. It was developed using consistent reference parameters and extensive earth and ocean tidal models. It was simultaneously solved for gravitational and tidal terms, earth orientation parameters, and the orbital parameters of 580 individual satellite arcs. The solution used only satellite tracking data acquired on 17 different satellites and is predominantly based upon the precise laser data taken by third generation systems. In all, 800,000 observations were used. A major improvement in field accuracy was obtained. For marine geodetic applications, long wavelength geoidal modeling is twice as good as in earlier satellite-only GEM models. Orbit determination accuracy has also been substantially advanced over a wide range of satellites that have been tested.

Using model order tests to determine sensory inputs in a motion study

NASA Technical Reports Server (NTRS)

Repperger, D. W.; Junker, A. M.

1977-01-01

In the study of motion effects on tracking performance, a problem of interest is the determination of what sensory inputs a human uses in controlling his tracking task. In the approach presented here a simple canonical model (FID or a proportional, integral, derivative structure) is used to model the human's input-output time series. A study of significant changes in reduction of the output error loss functional is conducted as different permutations of parameters are considered. Since this canonical model includes parameters which are related to inputs to the human (such as the error signal, its derivatives and integration), the study of model order is equivalent to the study of which sensory inputs are being used by the tracker. The parameters are obtained which have the greatest effect on reducing the loss function significantly. In this manner the identification procedure converts the problem of testing for model order into the problem of determining sensory inputs.

Evaluation of tactual displays for flight control

NASA Technical Reports Server (NTRS)

Levison, W. H.; Tanner, R. B.; Triggs, T. J.

1973-01-01

Manual tracking experiments were conducted to determine the suitability of tactual displays for presenting flight-control information in multitask situations. Although tracking error scores are considerably greater than scores obtained with a continuous visual display, preliminary results indicate that inter-task interference effects are substantially less with the tactual display in situations that impose high visual scanning workloads. The single-task performance degradation found with the tactual display appears to be a result of the coding scheme rather than the use of the tactual sensory mode per se. Analysis with the state-variable pilot/vehicle model shows that reliable predictions of tracking errors can be obtained for wide-band tracking systems once the pilot-related model parameters have been adjusted to reflect the pilot-display interaction.

Haptic control with environment force estimation for telesurgery.

PubMed

Bhattacharjee, Tapomayukh; Son, Hyoung Il; Lee, Doo Yong

2008-01-01

Success of telesurgical operations depends on better position tracking ability of the slave device. Improved position tracking of the slave device can lead to safer and less strenuous telesurgical operations. The two-channel force-position control architecture is widely used for better position tracking ability. This architecture requires force sensors for direct force feedback. Force sensors may not be a good choice in the telesurgical environment because of the inherent noise, and limitation in the deployable place and space. Hence, environment force estimation is developed using the concept of the robot function parameter matrix and a recursive least squares method. Simulation results show efficacy of the proposed method. The slave device successfully tracks the position of the master device, and the estimation error quickly becomes negligible.

Bulk Chemical and Hf/W Isotopic Consequences of Lossy Accretion

NASA Astrophysics Data System (ADS)

Dwyer, C. A.; Nimmo, F.; Chambers, J.

2013-12-01

The late stages of planetary accretion involve stochastic, large collisions [1]. Many of these collisions likely resulted in hit-and-run events [2] or erosion of existing bodies' crusts [3] or mantles [4]. Here we present a preliminary investigation into the effects of lossy late-stage accretion on the bulk chemistry and isotopic characteristics of the resulting planets. Our model is composed of two parts: (1) an N-body accretion code [5] tracks the orbital and collisional evolution of the terrestrial bodies, including hit-and-run and fragmentation events; (2) post-processing evolves the chemistry in light of radioactive decay and impact-related mixing and partial equilibration. Sixteen runs were performed using the MERCURY N-body code [5]; each run contained Jupiter and Saturn in their current orbits as well as approx 150 initial bodies. Different collisional outcomes including fragmentation are possible depending on the velocity, angle, mass ratio, and total mass of the impact (modified from [6, 7]). The masses of the core and mantle of each body are tracked throughout the simulation. All bodies are assigned an initial mantle mass fraction, y, of 0.7. We track the Hf and W evolution of these bodies. Radioactive decay occurs between impacts. We calculate the effect of an impact by assuming an idealized model of mixing and partial equilibration [8]. The core equilibration factor is a free parameter; we use 0.4. Partition coefficients are assumed constant. Diversity increases as final mass decreases. The range in final y changes from 0.66-0.72 for approx Earth-mass planets to 0.41-1 for the smallest bodies in the simulation. The scatter in tungsten anomaly increases from 0.79-4.0 for approx Earth-mass to 0.11-18 for the smallest masses. This behavior is similar to that observed in our solar system in terms of both bulk and isotopic chemistry. There is no single impact event which defines the final state of the body, therefore talking about a single, specific age of formation does not make sense. Instead, it must be recognized that terrestrial planet formation occurs over a range of time spanning many tens to perhaps hundreds of millions of years. We are currently performing sensitivity analyses to determine the effect on the tungsten isotopic anomalies of the final bodies. [1] Agnor et al. (1999), Icarus 142, 219-237. [2] Asphaug et al. (2006), Nature 439, 155-160. [3] O'Neill & Palme (2008), Phil Trans R Soc Lond A 366, 4205-4238. [4] Benz et al. (2007), Sp SciRev 132, 189-202. [5] Chambers (2013), Icarus, 224, 43-56. [6] Genda et al. (2012), ApJ 744, 137. [7] Leinhardt & Stewart (2012), ApJ 745, 79. [8] Nimmo et al. (2010), EPSL 292, 363-370.

Analysis of the track- and dose-averaged LET and LET spectra in proton therapy using the geant4 Monte Carlo code

PubMed Central

Guan, Fada; Peeler, Christopher; Bronk, Lawrence; Geng, Changran; Taleei, Reza; Randeniya, Sharmalee; Ge, Shuaiping; Mirkovic, Dragan; Grosshans, David; Mohan, Radhe; Titt, Uwe

2015-01-01

Purpose: The motivation of this study was to find and eliminate the cause of errors in dose-averaged linear energy transfer (LET) calculations from therapeutic protons in small targets, such as biological cell layers, calculated using the geant 4 Monte Carlo code. Furthermore, the purpose was also to provide a recommendation to select an appropriate LET quantity from geant 4 simulations to correlate with biological effectiveness of therapeutic protons. Methods: The authors developed a particle tracking step based strategy to calculate the average LET quantities (track-averaged LET, LETt and dose-averaged LET, LETd) using geant 4 for different tracking step size limits. A step size limit refers to the maximally allowable tracking step length. The authors investigated how the tracking step size limit influenced the calculated LETt and LETd of protons with six different step limits ranging from 1 to 500 μm in a water phantom irradiated by a 79.7-MeV clinical proton beam. In addition, the authors analyzed the detailed stochastic energy deposition information including fluence spectra and dose spectra of the energy-deposition-per-step of protons. As a reference, the authors also calculated the averaged LET and analyzed the LET spectra combining the Monte Carlo method and the deterministic method. Relative biological effectiveness (RBE) calculations were performed to illustrate the impact of different LET calculation methods on the RBE-weighted dose. Results: Simulation results showed that the step limit effect was small for LETt but significant for LETd. This resulted from differences in the energy-deposition-per-step between the fluence spectra and dose spectra at different depths in the phantom. Using the Monte Carlo particle tracking method in geant 4 can result in incorrect LETd calculation results in the dose plateau region for small step limits. The erroneous LETd results can be attributed to the algorithm to determine fluctuations in energy deposition along the tracking step in geant 4. The incorrect LETd values lead to substantial differences in the calculated RBE. Conclusions: When the geant 4 particle tracking method is used to calculate the average LET values within targets with a small step limit, such as smaller than 500 μm, the authors recommend the use of LETt in the dose plateau region and LETd around the Bragg peak. For a large step limit, i.e., 500 μm, LETd is recommended along the whole Bragg curve. The transition point depends on beam parameters and can be found by determining the location where the gradient of the ratio of LETd and LETt becomes positive. PMID:26520716

Tropospheric products of the second GOP European GNSS reprocessing (1996-2014)

NASA Astrophysics Data System (ADS)

Dousa, Jan; Vaclavovic, Pavel; Elias, Michal

2017-09-01

In this paper, we present results of the second reprocessing of all data from 1996 to 2014 from all stations in International Association of Geodesy (IAG) Reference Frame Sub-Commission for Europe (EUREF) Permanent Network (EPN) as performed at the Geodetic Observatory Pecný (GOP). While the original goal of this research was to ultimately contribute to the realization of a new European Terrestrial Reference System (ETRS), we also aim to provide a new set of GNSS (Global Navigation Satellite System) tropospheric parameter time series with possible applications to climate research. To achieve these goals, we improved a strategy to guarantee the continuity of these tropospheric parameters and we prepared several variants of troposphere modelling. We then assessed all solutions in terms of the repeatability of coordinates as an internal evaluation of applied models and strategies and in terms of zenith tropospheric delays (ZTDs) and horizontal gradients with those of the ERA-Interim numerical weather model (NWM) reanalysis. When compared to the GOP Repro1 (first EUREF reprocessing) solution, the results of the GOP Repro2 (second EUREF reprocessing) yielded improvements of approximately 50 and 25 % in the repeatability of the horizontal and vertical components, respectively, and of approximately 9 % in tropospheric parameters. Vertical repeatability was reduced from 4.14 to 3.73 mm when using the VMF1 mapping function, a priori ZHD (zenith hydrostatic delay), and non-tidal atmospheric loading corrections from actual weather data. Raising the elevation cut-off angle from 3 to 7° and then to 10° increased RMS from coordinates' repeatability, which was then confirmed by independently comparing GNSS tropospheric parameters with the NWM reanalysis. The assessment of tropospheric horizontal gradients with respect to the ERA-Interim revealed a strong sensitivity of estimated gradients to the quality of GNSS antenna tracking performance. This impact was demonstrated at the Mallorca station, where gradients systematically grew up to 5 mm during the period between 2003 and 2008, before this behaviour disappeared when the antenna at the station was changed. The impact of processing variants on long-term ZTD trend estimates was assessed at 172 EUREF stations with time series longer than 10 years. The most significant site-specific impact was due to the non-tidal atmospheric loading followed by the impact of changing the elevation cut-off angle from 3 to 10°. The other processing strategy had a very small or negligible impact on estimated trends.

Effects of dynamic aeroelasticity on handling qualities and pilot rating

NASA Technical Reports Server (NTRS)

Swaim, R. L.; Yen, W.-Y.

1978-01-01

Pilot performance parameters, such as pilot ratings, tracking errors, and pilot comments, were recorded and analyzed for a longitudinal pitch tracking task on a large, flexible aircraft. The tracking task was programmed on a fixed-base simulator with a CRT attitude director display of pitch angle command, pitch angle, and pitch angle error. Parametric variations in the undamped natural frequencies of the two lowest frequency symmetric elastic modes were made to induce varying degrees of rigid body and elastic mode interaction. The results indicate that such mode interaction can drastically affect the handling qualities and pilot ratings of the task.

Model of ballistic targets' dynamics used for trajectory tracking algorithms

NASA Astrophysics Data System (ADS)

Okoń-FÄ fara, Marta; Kawalec, Adam; Witczak, Andrzej

2017-04-01

There are known only few ballistic object tracking algorithms. To develop such algorithms and to its further testing, it is necessary to implement possibly simple and reliable objects' dynamics model. The article presents the dynamics' model of a tactical ballistic missile (TBM) including the three stages of flight: the boost stage and two passive stages - the ascending one and the descending one. Additionally, the procedure of transformation from the local coordinate system to the polar-radar oriented and the global is presented. The prepared theoretical data may be used to determine the tracking algorithm parameters and to its further verification.

Worth the "Likes"? The Use of Facebook among Plastic Surgeons and Its Perceived Impact.

PubMed

Chang, Jessica B; Woo, Shoshana L; Cederna, Paul S

2015-05-01

Facebook is the leading online media platform used by plastic surgeons. This study examined Facebook use among plastic surgeons and its perceived impact. A survey on Facebook use was distributed to two groups of plastic surgeons: 500 with professional Facebook pages and 500 without Facebook pages. Responses were stripped of identifying information and analyzed for statistical significance (p < 0.05). One hundred twenty-three total surveys were completed (12.3 percent response rate). No respondents with Facebook reported a negative impact on their practice, whereas 57 percent reported a very positive or positive impact. There was no correlation with perceived impact and number of "likes." Perceived advantages of Facebook included facilitation of patient feedback/communication (77 percent) and increased practice exposure (67 percent). Many surgeons (15 to 36 percent) did not follow the direct impact of Facebook on their practices. Some reported that Facebook was responsible for only one to 50 professional Web site hits and less than 5 percent of their new patient referrals in the past year. Estimated conversion-to-surgery rates were highly variable for Facebook users and nonusers. Most Facebook nonusers (67 percent) expected a "neutral" impact, expressing more concerns about unsolicited advertising (51 percent) and wasting time (47 percent). Plastic surgeons tend to perceive Facebook's impact on their practices as positive, but most do not track its direct effects on professional Web site hits, new referrals, or conversion-to-surgery rates. Plastic surgeons using Facebook are encouraged to monitor these parameters to determine whether its continued use is actually worthwhile.

Systematic Examination of Stardust Bulbous Track Wall Materials

NASA Technical Reports Server (NTRS)

Nakamura-Messenger, K.; Clemett, S. J.; Nguyen, A. N.; Berger, E. L.; Keller, L. P.; Messenger, S.

2013-01-01

Analyses of Comet Wild-2 samples returned by NASA's Stardust spacecraft have focused primarily on terminal particles (TPs) or well-preserved fine-grained materials along the track walls [1,2]. However much of the collected material was melted and mixed intimately with the aerogel by the hypervelocity impact [3,4]. We are performing systematic examinations of entire Stardust tracks to establish the mineralogy and origins of all comet Wild 2 components [7,8]. This report focuses on coordinated analyses of indigenous crystalline and amorphous/melt cometary materials along the aerogel track walls, their interaction with aerogel during collection and comparisons with their TPs.

Interannual Modulation of Northern Hemisphere Winter Storm Tracks by the QBO

NASA Astrophysics Data System (ADS)

Wang, Jiabao; Kim, Hye-Mi; Chang, Edmund K. M.

2018-03-01

Storm tracks, defined as the preferred regions of extratropical synoptic-scale disturbances, have remarkable impacts on global weather and climate systems. Causes of interannual storm track variation have been investigated mostly from a troposphere perspective. As shown in this study, Northern Hemisphere winter storm tracks are significantly modulated by the tropical stratosphere through the quasi-biennial oscillation (QBO). The North Pacific storm track shifts poleward during the easterly QBO winters associated with a dipole change in the eddy refraction and baroclinicity. The North Atlantic storm track varies vertically with a downward shrinking (upward expansion) in easterly (westerly) QBO winters associated with the change of the tropopause height. These results not only fill the knowledge gap of QBO-storm track relationship but also suggest a potential route to improve the seasonal prediction of extratropical storm activities owing to the high predictability of the QBO.

A novel AIF tracking method and comparison of DCE-MRI parameters using individual and population-based AIFs in human breast cancer

NASA Astrophysics Data System (ADS)

Li, Xia; Welch, E. Brian; Arlinghaus, Lori R.; Bapsi Chakravarthy, A.; Xu, Lei; Farley, Jaime; Loveless, Mary E.; Mayer, Ingrid A.; Kelley, Mark C.; Meszoely, Ingrid M.; Means-Powell, Julie A.; Abramson, Vandana G.; Grau, Ana M.; Gore, John C.; Yankeelov, Thomas E.

2011-09-01

Quantitative analysis of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) data requires the accurate determination of the arterial input function (AIF). A novel method for obtaining the AIF is presented here and pharmacokinetic parameters derived from individual and population-based AIFs are then compared. A Philips 3.0 T Achieva MR scanner was used to obtain 20 DCE-MRI data sets from ten breast cancer patients prior to and after one cycle of chemotherapy. Using a semi-automated method to estimate the AIF from the axillary artery, we obtain the AIF for each patient, AIFind, and compute a population-averaged AIF, AIFpop. The extended standard model is used to estimate the physiological parameters using the two types of AIFs. The mean concordance correlation coefficient (CCC) for the AIFs segmented manually and by the proposed AIF tracking approach is 0.96, indicating accurate and automatic tracking of an AIF in DCE-MRI data of the breast is possible. Regarding the kinetic parameters, the CCC values for Ktrans, vp and ve as estimated by AIFind and AIFpop are 0.65, 0.74 and 0.31, respectively, based on the region of interest analysis. The average CCC values for the voxel-by-voxel analysis are 0.76, 0.84 and 0.68 for Ktrans, vp and ve, respectively. This work indicates that Ktrans and vp show good agreement between AIFpop and AIFind while there is a weak agreement on ve.

Ichnological evidence of Megalosaurid Dinosaurs Crossing Middle Jurassic Tidal Flats

NASA Astrophysics Data System (ADS)

Razzolini, Novella L.; Oms, Oriol; Castanera, Diego; Vila, Bernat; Santos, Vanda Faria Dos; Galobart, Àngel

2016-08-01

A new dinosaur tracksite in the Vale de Meios quarry (Serra de Aire Formation, Bathonian, Portugal)preserves more than 700 theropod tracks. They are organized in at least 80 unidirectional trackways arranged in a bimodal orientation pattern (W/NW and E/SE). Quantitative and qualitative comparisons reveal that the large tridactyl, elongated and asymmetric tracks resemble the typical Late Jurassic-Early Cretaceous Megalosauripus ichnogenus in all morphometric parameters. Few of the numerous tracks are preserved as elite tracks while the rest are preserved as different gradients of modified true tracks according to water content, erosive factors, radial fractures and internal overtrack formations. Taphonomical determinations are consistent with paleoenvironmental observations that indicate an inter-tidal flat located at the margin of a coastal barrier. The Megalosauripus tracks represent the oldest occurrence of this ichnotaxon and are attributed to large megalosaurid dinosaurs. Their occurrence in Vale de Meios tidal flat represents the unique paleoethological evidence of megalosaurids moving towards the lagoon, most likley during the low tide periods with feeding purposes.

Ichnological evidence of Megalosaurid Dinosaurs Crossing Middle Jurassic Tidal Flats.

PubMed

Razzolini, Novella L; Oms, Oriol; Castanera, Diego; Vila, Bernat; Santos, Vanda Faria Dos; Galobart, Àngel

2016-08-19

A new dinosaur tracksite in the Vale de Meios quarry (Serra de Aire Formation, Bathonian, Portugal)preserves more than 700 theropod tracks. They are organized in at least 80 unidirectional trackways arranged in a bimodal orientation pattern (W/NW and E/SE). Quantitative and qualitative comparisons reveal that the large tridactyl, elongated and asymmetric tracks resemble the typical Late Jurassic-Early Cretaceous Megalosauripus ichnogenus in all morphometric parameters. Few of the numerous tracks are preserved as elite tracks while the rest are preserved as different gradients of modified true tracks according to water content, erosive factors, radial fractures and internal overtrack formations. Taphonomical determinations are consistent with paleoenvironmental observations that indicate an inter-tidal flat located at the margin of a coastal barrier. The Megalosauripus tracks represent the oldest occurrence of this ichnotaxon and are attributed to large megalosaurid dinosaurs. Their occurrence in Vale de Meios tidal flat represents the unique paleoethological evidence of megalosaurids moving towards the lagoon, most likley during the low tide periods with feeding purposes.

Tracking strategies for laser ranging to multiple satellite targets

NASA Technical Reports Server (NTRS)

Robbins, J. W.; Smith, D. E.; Kolenkiewicz, R.

1994-01-01

By the middle of the decade, several new Laser Geodynamic Satellites will be launched to join the current constellation comprised of the laser geodynamic satellite (LAGEOS) (US), Starlette (France), Ajisai (Japan), and Etalon I and II (USSR). The satellites to be launched, LAGEOS II and III (US & Italy), and Stella (France), will be injected into orbits that differ from the existing constellation so that geodetic and gravimetric quantities are sampled to enhance their resolution and accuracy. An examination of various possible tracking strategies adopted by the network of laser tracking stations has revealed that the recovery of precise geodetic parameters can be obtained over shorter intervals than is currently obtainable with the present constellation of satellites. This is particularly important in the planning of mobile laser tracking operations, given a network of permanently operating tracking sites. Through simulations, it is shown that laser tracking of certain satellite passes, pre-selected to provide optimal sky-coverage, provides the means to acquire a sufficient amount of data to allow the recovery of 1 cm station positions.

Intra-Trackway Morphological Variations Due to Substrate Consistency: The El Frontal Dinosaur Tracksite (Lower Cretaceous, Spain)

PubMed Central

Razzolini, Novella L.; Vila, Bernat; Castanera, Diego; Falkingham, Peter L.; Barco, José Luis; Canudo, José Ignacio; Manning, Phillip L.; Galobart, Àngel

2014-01-01

An ichnological and sedimentological study of the El Frontal dinosaur tracksite (Early Cretaceous, Cameros basin, Soria, Spain) highlights the pronounced intra-trackway variation found in track morphologies of four theropod trackways. Photogrammetric 3D digital models revealed various and distinct intra-trackway morphotypes, which reflect changes in footprint parameters such as the pace length, the track length, depth, and height of displacement rims. Sedimentological analyses suggest that the original substrate was non-homogenous due to lateral changes in adjoining microfacies. Multidata analyses indicate that morphological differences in these deep and shallow tracks represent a part of a continuum of track morphologies and geometries produced by a gradient of substrate consistencies across the site. This implies that the large range of track morphologies at this site resulted from similar trackmakers crossing variable facies. The trackways at the El Frontal site present an exemplary case of how track morphology, and consequently potential ichnotaxa, can vary, even when produced by a single trackmaker. PMID:24699696

Centralized Multi-Sensor Square Root Cubature Joint Probabilistic Data Association

PubMed Central

Liu, Jun; Li, Gang; Qi, Lin; Li, Yaowen; He, You

2017-01-01

This paper focuses on the tracking problem of multiple targets with multiple sensors in a nonlinear cluttered environment. To avoid Jacobian matrix computation and scaling parameter adjustment, improve numerical stability, and acquire more accurate estimated results for centralized nonlinear tracking, a novel centralized multi-sensor square root cubature joint probabilistic data association algorithm (CMSCJPDA) is proposed. Firstly, the multi-sensor tracking problem is decomposed into several single-sensor multi-target tracking problems, which are sequentially processed during the estimation. Then, in each sensor, the assignment of its measurements to target tracks is accomplished on the basis of joint probabilistic data association (JPDA), and a weighted probability fusion method with square root version of a cubature Kalman filter (SRCKF) is utilized to estimate the targets’ state. With the measurements in all sensors processed CMSCJPDA is derived and the global estimated state is achieved. Experimental results show that CMSCJPDA is superior to the state-of-the-art algorithms in the aspects of tracking accuracy, numerical stability, and computational cost, which provides a new idea to solve multi-sensor tracking problems. PMID:29113085

Centralized Multi-Sensor Square Root Cubature Joint Probabilistic Data Association.

PubMed

Liu, Yu; Liu, Jun; Li, Gang; Qi, Lin; Li, Yaowen; He, You

2017-11-05

This paper focuses on the tracking problem of multiple targets with multiple sensors in a nonlinear cluttered environment. To avoid Jacobian matrix computation and scaling parameter adjustment, improve numerical stability, and acquire more accurate estimated results for centralized nonlinear tracking, a novel centralized multi-sensor square root cubature joint probabilistic data association algorithm (CMSCJPDA) is proposed. Firstly, the multi-sensor tracking problem is decomposed into several single-sensor multi-target tracking problems, which are sequentially processed during the estimation. Then, in each sensor, the assignment of its measurements to target tracks is accomplished on the basis of joint probabilistic data association (JPDA), and a weighted probability fusion method with square root version of a cubature Kalman filter (SRCKF) is utilized to estimate the targets' state. With the measurements in all sensors processed CMSCJPDA is derived and the global estimated state is achieved. Experimental results show that CMSCJPDA is superior to the state-of-the-art algorithms in the aspects of tracking accuracy, numerical stability, and computational cost, which provides a new idea to solve multi-sensor tracking problems.

Vegetation associated with different walking track types in the Kosciuszko alpine area, Australia.

PubMed

Hill, Wendy; Pickering, Catherine Marina

2006-01-01

Tourism infrastructure such as walking tracks can have negative effects on vegetation including in mountain regions. In the alpine area around continental Australia's highest mountain, Mt Kosciuszko (2228 m), there is a range of walking tracks (paved, gravel and raised steel mesh surfaces) in addition to an extensive network of informal/non-hardened tracks. Vegetation characteristics were compared between track types on/under tracks, on the track verge, and in the adjacent native vegetation. For a raised steel mesh walkway there was no difference in vegetation under the walkway, on the verge, and 3m away. In contrast, for a non-hardened track there was 35% bare ground on the track surface but no other detectable impacts. Gravel and paved tracks had distinct verges largely comprising bare ground and exotic species. For non-hardened tracks there was an estimated 270 m2 of disturbance per km of track. For wide gravel tracks the combined area of bare ground, exotic plants and gravel was estimated as 4290 m2 per km, while for narrow gravel tracks it was estimated as 2940 m2 per km. For paved tracks there was around 2680 m2 per km of damage. In contrast, there was no detectable effect of raised steel mesh walkway on vegetation highlighting some of the benefits of this surface over other track types.

Parameter estimation of a three-axis spacecraft simulator using recursive least-squares approach with tracking differentiator and Extended Kalman Filter

NASA Astrophysics Data System (ADS)

Xu, Zheyao; Qi, Naiming; Chen, Yukun

2015-12-01

Spacecraft simulators are widely used to study the dynamics, guidance, navigation, and control of a spacecraft on the ground. A spacecraft simulator can have three rotational degrees of freedom by using a spherical air-bearing to simulate a frictionless and micro-gravity space environment. The moment of inertia and center of mass are essential for control system design of ground-based three-axis spacecraft simulators. Unfortunately, they cannot be known precisely. This paper presents two approaches, i.e. a recursive least-squares (RLS) approach with tracking differentiator (TD) and Extended Kalman Filter (EKF) method, to estimate inertia parameters. The tracking differentiator (TD) filter the noise coupled with the measured signals and generate derivate of the measured signals. Combination of two TD filters in series obtains the angular accelerations that are required in RLS (TD-TD-RLS). Another method that does not need to estimate the angular accelerations is using the integrated form of dynamics equation. An extended TD (ETD) filter which can also generate the integration of the function of signals is presented for RLS (denoted as ETD-RLS). States and inertia parameters are estimated simultaneously using EKF. The observability is analyzed. All proposed methods are illustrated by simulations and experiments.

Assessing alternatives for directional detection of a halo of weakly interacting massive particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Copi, Craig J.; Krauss, Lawrence M.; Department of Astronomy, Case Western Reserve University, 10900 Euclid Ave., Cleveland, Ohio 44106-7079

2007-01-15

The future of direct terrestrial WIMP detection lies on two fronts: new, much larger low background detectors sensitive to energy deposition, and detectors with directional sensitivity. The former can explore a large range of WIMP parameter space using well-tested technology while the latter may be necessary if one is to disentangle particle physics parameters from astrophysical halo parameters. Because directional detectors will be quite difficult to construct it is worthwhile exploring in advance generally which experimental features will yield the greatest benefits at the lowest costs. We examine the sensitivity of directional detectors with varying angular tracking resolution with andmore » without the ability to distinguish forward versus backward recoils, and compare these to the sensitivity of a detector where the track is projected onto a two-dimensional plane. The latter detector regardless of where it is placed on the Earth, can be oriented to produce a significantly better discrimination signal than a 3D detector without this capability, and with sensitivity within a factor of 2 of a full 3D tracking detector. Required event rates to distinguish signals from backgrounds for a simple isothermal halo range from the low teens in the best case to many thousands in the worst.« less

Impacts of extratropical storm tracks on Arctic sea ice export through Fram Strait

NASA Astrophysics Data System (ADS)

Wei, Jianfen; Zhang, Xiangdong; Wang, Zhaomin

2018-05-01

Studies have indicated regime shifts in atmospheric circulation, and associated changes in extratropical storm tracks and Arctic storm activity, in particular on the North Atlantic side of the Arctic Ocean. To improve understanding of changes in Arctic sea ice mass balance, we examined the impacts of the changed storm tracks and cyclone activity on Arctic sea ice export through Fram Strait by using a high resolution global ocean-sea ice model, MITgcm-ECCO2. The model was forced by the Japanese 25-year Reanalysis (JRA-25) dataset. The results show that storm-induced strong northerly wind stress can cause simultaneous response of daily sea ice export and, in turn, exert cumulative effects on interannual variability and long-term changes of sea ice export. Further analysis indicates that storm impact on sea ice export is spatially dependent. The storms occurring southeast of Fram Strait exhibit the largest impacts. The weakened intensity of winter (in this study winter is defined as October-March and summer as April-September) storms in this region after 1994/95 could be responsible for the decrease of total winter sea ice export during the same time period.

Self-paced model learning for robust visual tracking

NASA Astrophysics Data System (ADS)

Huang, Wenhui; Gu, Jason; Ma, Xin; Li, Yibin

2017-01-01

In visual tracking, learning a robust and efficient appearance model is a challenging task. Model learning determines both the strategy and the frequency of model updating, which contains many details that could affect the tracking results. Self-paced learning (SPL) has recently been attracting considerable interest in the fields of machine learning and computer vision. SPL is inspired by the learning principle underlying the cognitive process of humans, whose learning process is generally from easier samples to more complex aspects of a task. We propose a tracking method that integrates the learning paradigm of SPL into visual tracking, so reliable samples can be automatically selected for model learning. In contrast to many existing model learning strategies in visual tracking, we discover the missing link between sample selection and model learning, which are combined into a single objective function in our approach. Sample weights and model parameters can be learned by minimizing this single objective function. Additionally, to solve the real-valued learning weight of samples, an error-tolerant self-paced function that considers the characteristics of visual tracking is proposed. We demonstrate the robustness and efficiency of our tracker on a recent tracking benchmark data set with 50 video sequences.

IMM tracking of a theater ballistic missile during boost phase

NASA Astrophysics Data System (ADS)

Hutchins, Robert G.; San Jose, Anthony

1998-09-01

Since the SCUD launches in the Gulf War, theater ballistic missile (TBM) systems have become a growing concern for the US military. Detection, tracking and engagement during boost phase or shortly after booster cutoff are goals that grow in importance with the proliferation of weapons of mass destruction. This paper addresses the performance of tracking algorithms for TBMs during boost phase and across the transition to ballistic flight. Three families of tracking algorithms are examined: alpha-beta-gamma trackers, Kalman-based trackers, and the interactive multiple model (IMM) tracker. In addition, a variation on the IMM to include prior knowledge of a booster cutoff parameter is examined. Simulated data is used to compare algorithms. Also, the IMM tracker is run on an actual ballistic missile trajectory. Results indicate that IMM trackers show significant advantage in tracking through the model transition represented by booster cutoff.

Adaptive learning compressive tracking based on Markov location prediction

NASA Astrophysics Data System (ADS)

Zhou, Xingyu; Fu, Dongmei; Yang, Tao; Shi, Yanan

2017-03-01

Object tracking is an interdisciplinary research topic in image processing, pattern recognition, and computer vision which has theoretical and practical application value in video surveillance, virtual reality, and automatic navigation. Compressive tracking (CT) has many advantages, such as efficiency and accuracy. However, when there are object occlusion, abrupt motion and blur, similar objects, and scale changing, the CT has the problem of tracking drift. We propose the Markov object location prediction to get the initial position of the object. Then CT is used to locate the object accurately, and the classifier parameter adaptive updating strategy is given based on the confidence map. At the same time according to the object location, extract the scale features, which is able to deal with object scale variations effectively. Experimental results show that the proposed algorithm has better tracking accuracy and robustness than current advanced algorithms and achieves real-time performance.

Observer-based state tracking control of uncertain stochastic systems via repetitive controller

NASA Astrophysics Data System (ADS)

Sakthivel, R.; Susana Ramya, L.; Selvaraj, P.

2017-08-01

This paper develops the repetitive control scheme for state tracking control of uncertain stochastic time-varying delay systems via equivalent-input-disturbance approach. The main purpose of this work is to design a repetitive controller to guarantee the tracking performance under the effects of unknown disturbances with bounded frequency and parameter variations. Specifically, a new set of linear matrix inequality (LMI)-based conditions is derived based on the suitable Lyapunov-Krasovskii functional theory for designing a repetitive controller which guarantees stability and desired tracking performance. More precisely, an equivalent-input-disturbance estimator is incorporated into the control design to reduce the effect of the external disturbances. Simulation results are provided to demonstrate the desired control system stability and their tracking performance. A practical stream water quality preserving system is also provided to show the effectiveness and advantage of the proposed approach.

Left atrium function by 2D speckle tracking in aortic valve disease.

PubMed

Salas-Pacheco, Jose L; Ávila-Vanzzini, Nydia; Eugenia, Ruiz-Esparza M; Arias-Godínez, Jose A

2016-12-01

A paucity of data exists about left atrium (LA) function in aortic valve stenosis (AS) or regurgitation (AR). Two-dimensional speckle tracking echocardiography allows the noninvasive study of LA functional disturbances in aortic valve disease and their impact in the development of pulmonary hypertension (PH). Consecutive patients with moderate or severe AS or AR were included. Left ventricle (LV) and LA speckle tracking strain quantification was performed. We included 42 patients with AS and 30 with AR. Differences were not found in LA volumes and strain in AS or AR. The LA volumetric derangements parallel the decrease in LA longitudinal strain. Maximum LA volume, minimum LA volume, and indexed LA volume were higher in severe valvular disease (SVD) than in moderate [23 cc (P=.018, IC 95% : 4-41), 16 cc (P=.035, IC 95% : 2-31), and 14 cc (P=.022, IC 95% : 2-25), respectively], occurred in the same way with LA strain in the conduit (6.3%, P=.034, IC 95% : 1-12) and reservoir (7.1%, P=.04, IC 95% : 2-14) phases. In multivariable model, strain of reservoir phase was the variable mainly associated with PH; each decrease in one unit of strain of reservoir phase increased 6% the PH probability (OR: 1.06, P=.01). This study demonstrates that in patients with AS and AR, the LA has a similar behavior and that exist a close correlation between LA volumetric and functional parameters. The variable mainly associated with PH was LA strain of reservoir phase. © 2016, Wiley Periodicals, Inc.

Educational Tracking and Juvenile Deviance in Taiwan: Direct Effect, Indirect Effect, or Both.

PubMed

Lin, Wen-Hsu; Yi, Chin-Chun

2016-02-01

Educational tracking in Chinese society is quite different from that in Western society, in that the allocation to either the vocational or academic track is based on a national entrance examination, which happens at ninth grade (age 14-15). Hence, students in many Asian countries (e.g., China and Taiwan) have to face academic tracking in early adolescence. Because of cultural emphasis on education in Taiwan, the impact of tracking on deviance is profound and can be seen as a crucial life-event. With this concept in mind, we examine how educational tracking influences adolescent deviance during high school. In addition, we also examine how educational tracking may indirectly influence deviance through other life domains, including depression, delinquent peer association, and school attachment. By using longitudinal data (the Taiwan Youth Project), we find that educational tracking increases deviance not only directly but also indirectly through delinquent peers and low school attachment. Some implications and limitations are also discussed. © The Author(s) 2014.

Evaluating the Impact of Internships - Longitudinal Participant Tracking in the Soars Program

NASA Astrophysics Data System (ADS)

Haacker, R.; Sloan, V.

2014-12-01

While there is widespread agreement about the benefits of research internship experiences for students, long-term tracking of student progress beyond the summer experience is challenging. Coordinated tracking can effectively document program impact, inform programmatic improvement, and identifying gaps in the internship effort. Tracking can also strengthen diversity efforts and the retention of students from underrepresented groups. Continuous follow-up and guidance can only be provided to students if we know where they are, what they are doing and what they need in order to stay engaged in the field. The SOARS Program at the National Center for Atmospheric Research has supported undergraduate students for over 18 years to enter and succeed in graduate school. Over 85% of SOARS participants have transitioned to geoscience graduate programs or the STEM workforce. The SOARS mission is to broaden participation in the atmospheric and related sciences by engaging students from groups historically under-represented in science, including Black or African-American, American Indian or Alaska Native, Hispanic or Latino, female, first-generation college students, and students with disabilities. SOARS relies on proven intervention strategies such as multi-year research experiences, multifaceted mentoring, and a strong learning community. Fostering relationships developed during this time using a wider range of technologies and program longevity play important roles in tracking participants over time. This presentation will highlight significant program results and share the tracking and evaluation techniques utilized in SOARS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tien, C; Brewer, M; Studenski, M

Purpose: Dynamic-jaw tracking maximizes the area blocked by both jaw and MLC in RapidArc. We developed a method to quantify jaw tracking. Methods: An Eclipse Scripting API (ESAPI) was used to export beam parameters for each arc’s control points. The specific beam parameters extracted were: gantry angle, control point number, meterset, x-jaw positions, y-jaw positions, MLC bank-number, MLC leaf-number, and MLC leaf-position. Each arc contained 178 control points with 120 MLC positions. MATLAB routines were written to process these parameters in order to calculate both the beam aperture (unblocked) size for each control point. An average aperture size was weightedmore » by meterset. Jaw factor was defined as the ratio between dynamic-jaw to static-jaw aperture size. Jaw factor was determined for forty retrospectively replanned patients treated with static-jaw delivery sites including lung, brain, prostate, H&N, rectum, and bladder. Results: Most patients had multiple arcs and reduced-field boosts, resulting in 151 fields. Of these, the lowest (0.4722) and highest (0.9622) jaw factor was observed in prostate and rectal cases, respectively. The median jaw factor was 0.7917 meaning there is the potential unincreased blocking by 20%. Clinically, the dynamic-jaw tracking represents an area surrounding the target which would receive MLC-only leakage transmission of 1.68% versus 0.1% with jaws. Jaw-tracking was more pronounced at areas farther from the target. In prostate patients, the rectum and bladder had 5.5% and 6.3% lower mean dose, respectively; the structures closer to the prostate such as the rectum and bladder both had 1.4% lower mean dose. Conclusion: A custom ESAPI script was coupled with a MATLAB routine in order to extract beam parameters from static-jaw plans and their replanned dynamic-jaw deliveries. The effects were quantified using jaw factor which is the ratio between the meterset weighted aperture size for dynamic-jaw fields versus static-jaw fields.« less

CPV for the rooftop market: novel approaches to tracking integration in photovoltaic modules

NASA Astrophysics Data System (ADS)

Apostoleris, Harry; Stefancich, Marco; Alexander-Katz, Alfredo; Chiesa, Matteo

2016-03-01

Concentrated photovoltaics (CPV) has long been recognized as an effective approach to enabling the use of high cost, high-efficiency solar cells for enhanced solar energy conversion, but is excluded from the domestic rooftop market due to the requirement that solar concentrators track the sun. This market may be opened up by integrating of the tracking mechanism into the module itself. Tracking integration may take the form of a miniaturization of a conventional tracking apparatus, or optical tracking, in which tracking is achieved through variation of optical properties such as refractive index or transparency rather than mechanical movement of the receiver. We have demonstrated a simple system using a heat-responsive transparency switching material to create a moving aperture that tracks the position of a moving light spot. We use this behavior to create a concentrating light trap with a moving aperture that reactively tracks the sun. Taking the other approach, we have fabricated 3D-printed parabolic mini-concentrators which can track the sun using small motors in a low-profile geometry. We characterize the performance of the concentrators and consider the impact of tracking integration on the broader PV market.

VTAC: virtual terrain assisted impact assessment for cyber attacks

NASA Astrophysics Data System (ADS)

Argauer, Brian J.; Yang, Shanchieh J.

2008-03-01

Overwhelming intrusion alerts have made timely response to network security breaches a difficult task. Correlating alerts to produce a higher level view of intrusion state of a network, thus, becomes an essential element in network defense. This work proposes to analyze correlated or grouped alerts and determine their 'impact' to services and users of the network. A network is modeled as 'virtual terrain' where cyber attacks maneuver. Overlaying correlated attack tracks on virtual terrain exhibits the vulnerabilities exploited by each track and the relationships between them and different network entities. The proposed impact assessment algorithm utilizes the graph-based virtual terrain model and combines assessments of damages caused by the attacks. The combined impact scores allow to identify severely damaged network services and affected users. Several scenarios are examined to demonstrate the uses of the proposed Virtual Terrain Assisted Impact Assessment for Cyber Attacks (VTAC).

Clinical evidence of traditional vs fast track recovery methodologies after total arthroplasty for osteoarthritic knee treatment. A retrospective observational study

PubMed Central

Castorina, Sergio; Guglielmino, Claudia; Castrogiovanni, Paola; Szychlinska, Marta Anna; Ioppolo, Francesco; Massimino, Paolo; Leonardi, Pietro; Maci, Christian; Iannuzzi, Maurizio; Di Giunta, Angelo; Musumeci, Giuseppe

2017-01-01

Summary Background During the last years, programs to enhance postoperative recovery and decrease morbidity after total knee arthroplasty, have been developed across a variety of surgical procedures and referred to as “Fast-Track Surgery”. In this study we aimed to find some answers in the management of osteoarthritic patients subjected to total knee arthroplasty, by using the Fast-Track methodology. To this purpose we evaluated parameters such as early mobilization of patients, better pain management, bleeding, possible complications, reduced hospitalization time, an overall improved recovery and patient satisfaction. Methods 132 patients were selected, of which, 95 treated with “Fast Track” method and 37 treated with traditional method (control group). All the patients were hospitalized and underwent the same rehabilitation program for the first three days after surgery. Results In both groups, the parameters of pain and deformity demonstrated the most rapid improvement, while those of function and movement were normalized as gradual and progressive improvement over the next 2 months. The different functional test used (Barthel, MRC, VAS) showed that the mean values were significantly greater in Fast Track group when compared to the control. Conclusion The results of the study confirm that the application of the Fast Track protocol in orthopaedics after total knee replacement results in rapid post-surgery recovery. Level of evidence IV. Case series, low-quality cohort or case-control studies. PMID:29387645

Impact of Short Interval SMS Digital Data on Wind Vector Determination for a Severe Local Storms Area

NASA Technical Reports Server (NTRS)

Peslen, C. A.

1979-01-01

The impact of 5 minute interval SMS-2 visible digital image data in analyzing severe local storms is examined using wind vectors derived from cloud tracking on time lapsed sequence of geosynchronous satellite images. The cloud tracking areas are located in the Central Plains, where on 6 May 1975, hail-producing thunderstorms occurred ahead of a well defined dry line. The results demonstrate that satellite-derived wind vectors and their associated divergence fields complement conventional meteorological analyses in describing the conditions preceding severe local storm development.

Influence of tunnel and soil parameters on vibrations from underground railways

NASA Astrophysics Data System (ADS)

Gupta, S.; Stanus, Y.; Lombaert, G.; Degrande, G.

2009-10-01

A parametric study is performed to identify the key parameters which have an important influence on the generation and propagation of vibrations from underground railways. In this paper, the parameters related to the tunnel and the soil are considered and their influence on the free field response is studied. The coupled periodic finite element-boundary element model and the pipe-in-pipe model have been used for this study. Both models account for the dynamic interaction between the train, the track, the tunnel and the soil. A general analytical formulation is used to compute the response of three-dimensional invariant or periodic media that are excited by moving loads. The response to moving loads is written in terms of the axle loads and the transfer functions. The parametric study can be carried out by separately analyzing the variations in the axle loads and the transfer functions. The axle loads are mainly influenced by the parameters related to the vehicle and the track, while the transfer functions are influenced by the properties of the track, the tunnel and the soil. In the present paper, the parameters related to the tunnel and soil are investigated. It is observed that the material damping and the shear modulus of the soil have an important influence on the propagation of vibrations. The influence of structural changes to the tunnel as well as geometrical properties such as the size and shape of the tunnel is investigated. It is observed that a larger tunnel results in a smaller response above the tunnel as more energy is radiated downwards. Moreover, it is demonstrated that the tunnel geometry has a considerable influence on the response closer to the tunnel.

Direct and accelerated parameter mapping using the unscented Kalman filter.

PubMed

Zhao, Li; Feng, Xue; Meyer, Craig H

2016-05-01

To accelerate parameter mapping using a new paradigm that combines image reconstruction and model regression as a parameter state-tracking problem. In T2 mapping, the T2 map is first encoded in parameter space by multi-TE measurements and then encoded by Fourier transformation with readout/phase encoding gradients. Using a state transition function and a measurement function, the unscented Kalman filter can describe T2 mapping as a dynamic system and directly estimate the T2 map from the k-space data. The proposed method was validated with a numerical brain phantom and volunteer experiments with a multiple-contrast spin echo sequence. Its performance was compared with a conjugate-gradient nonlinear inversion method at undersampling factors of 2 to 8. An accelerated pulse sequence was developed based on this method to achieve prospective undersampling. Compared with the nonlinear inversion reconstruction, the proposed method had higher precision, improved structural similarity and reduced normalized root mean squared error, with acceleration factors up to 8 in numerical phantom and volunteer studies. This work describes a new perspective on parameter mapping by state tracking. The unscented Kalman filter provides a highly accelerated and efficient paradigm for T2 mapping. © 2015 Wiley Periodicals, Inc.

Human pose tracking from monocular video by traversing an image motion mapped body pose manifold

NASA Astrophysics Data System (ADS)

Basu, Saurav; Poulin, Joshua; Acton, Scott T.

2010-01-01

Tracking human pose from monocular video sequences is a challenging problem due to the large number of independent parameters affecting image appearance and nonlinear relationships between generating parameters and the resultant images. Unlike the current practice of fitting interpolation functions to point correspondences between underlying pose parameters and image appearance, we exploit the relationship between pose parameters and image motion flow vectors in a physically meaningful way. Change in image appearance due to pose change is realized as navigating a low dimensional submanifold of the infinite dimensional Lie group of diffeomorphisms of the two dimensional sphere S2. For small changes in pose, image motion flow vectors lie on the tangent space of the submanifold. Any observed image motion flow vector field is decomposed into the basis motion vector flow fields on the tangent space and combination weights are used to update corresponding pose changes in the different dimensions of the pose parameter space. Image motion flow vectors are largely invariant to style changes in experiments with synthetic and real data where the subjects exhibit variation in appearance and clothing. The experiments demonstrate the robustness of our method (within +/-4° of ground truth) to style variance.

A novel fully automatic scheme for fiducial marker-based alignment in electron tomography.

PubMed

Han, Renmin; Wang, Liansan; Liu, Zhiyong; Sun, Fei; Zhang, Fa

2015-12-01

Although the topic of fiducial marker-based alignment in electron tomography (ET) has been widely discussed for decades, alignment without human intervention remains a difficult problem. Specifically, the emergence of subtomogram averaging has increased the demand for batch processing during tomographic reconstruction; fully automatic fiducial marker-based alignment is the main technique in this process. However, the lack of an accurate method for detecting and tracking fiducial markers precludes fully automatic alignment. In this paper, we present a novel, fully automatic alignment scheme for ET. Our scheme has two main contributions: First, we present a series of algorithms to ensure a high recognition rate and precise localization during the detection of fiducial markers. Our proposed solution reduces fiducial marker detection to a sampling and classification problem and further introduces an algorithm to solve the parameter dependence of marker diameter and marker number. Second, we propose a novel algorithm to solve the tracking of fiducial markers by reducing the tracking problem to an incomplete point set registration problem. Because a global optimization of a point set registration occurs, the result of our tracking is independent of the initial image position in the tilt series, allowing for the robust tracking of fiducial markers without pre-alignment. The experimental results indicate that our method can achieve an accurate tracking, almost identical to the current best one in IMOD with half automatic scheme. Furthermore, our scheme is fully automatic, depends on fewer parameters (only requires a gross value of the marker diameter) and does not require any manual interaction, providing the possibility of automatic batch processing of electron tomographic reconstruction. Copyright © 2015 Elsevier Inc. All rights reserved.

Evaluation of GPUs as a level-1 track trigger for the High-Luminosity LHC

NASA Astrophysics Data System (ADS)

Mohr, H.; Dritschler, T.; Ardila, L. E.; Balzer, M.; Caselle, M.; Chilingaryan, S.; Kopmann, A.; Rota, L.; Schuh, T.; Vogelgesang, M.; Weber, M.

2017-04-01

In this work, we investigate the use of GPUs as a way of realizing a low-latency, high-throughput track trigger, using CMS as a showcase example. The CMS detector at the Large Hadron Collider (LHC) will undergo a major upgrade after the long shutdown from 2024 to 2026 when it will enter the high luminosity era. During this upgrade, the silicon tracker will have to be completely replaced. In the High Luminosity operation mode, luminosities of 5-7 × 1034 cm-2s-1 and pileups averaging at 140 events, with a maximum of up to 200 events, will be reached. These changes will require a major update of the triggering system. The demonstrated systems rely on dedicated hardware such as associative memory ASICs and FPGAs. We investigate the use of GPUs as an alternative way of realizing the requirements of the L1 track trigger. To this end we implemeted a Hough transformation track finding step on GPUs and established a low-latency RDMA connection using the PCIe bus. To showcase the benefits of floating point operations, made possible by the use of GPUs, we present a modified algorithm. It uses hexagonal bins for the parameter space and leads to a more truthful representation of the possible track parameters of the individual hits in Hough space. This leads to fewer duplicate candidates and reduces fake track candidates compared to the regular approach. With data-transfer latencies of 2 μs and processing times for the Hough transformation as low as 3.6 μs, we can show that latencies are not as critical as expected. However, computing throughput proves to be challenging due to hardware limitations.

First results of the silicon telescope using an 'artificial retina' for fast track finding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neri, N.; Abba, A.; Caponio, F.

We present the first results of the prototype of a silicon tracker with trigger capabilities based on a novel approach for fast track finding. The working principle of the 'artificial retina' is inspired by the processing of visual images by the brain and it is based on extensive parallelization of data distribution and pattern recognition. The algorithm has been implemented in commercial FPGAs in three main logic modules: a switch for the routing of the detector hits, a pool of engines for the digital processing of the hits, and a block for the calculation of the track parameters. The architecturemore » is fully pipelined and allows the reconstruction of real-time tracks with a latency less then 100 clock cycles, corresponding to 0.25 microsecond at 400 MHz clock. The silicon telescope consists of 8 layers of single-sided silicon strip detectors with 512 strips each. The detector size is about 10 cm x 10 cm and the strip pitch is 183 μm. The detectors are read out by the Beetle chip, a custom ASICs developed for LHCb, which provides the measurement of the hit position and pulse height of 128 channels. The 'artificial retina' algorithm has been implemented on custom data acquisition boards based on FPGAs Xilinx Kintex 7 lx160. The parameters of the tracks detected are finally transferred to host PC via USB 3.0. The boards manage the read-out ASICs and the sampling of the analog channels. The read-out is performed at 40 MHz on 4 channels for each ASIC that corresponds to a decoding of the telescope information at 1.1 MHz. We report on the first results of the fast tracking device and compare with simulations. (authors)« less

On the bistable zone of milling processes

PubMed Central

Dombovari, Zoltan; Stepan, Gabor

2015-01-01

A modal-based model of milling machine tools subjected to time-periodic nonlinear cutting forces is introduced. The model describes the phenomenon of bistability for certain cutting parameters. In engineering, these parameter domains are referred to as unsafe zones, where steady-state milling may switch to chatter for certain perturbations. In mathematical terms, these are the parameter domains where the periodic solution of the corresponding nonlinear, time-periodic delay differential equation is linearly stable, but its domain of attraction is limited due to the existence of an unstable quasi-periodic solution emerging from a secondary Hopf bifurcation. A semi-numerical method is presented to identify the borders of these bistable zones by tracking the motion of the milling tool edges as they might leave the surface of the workpiece during the cutting operation. This requires the tracking of unstable quasi-periodic solutions and the checking of their grazing to a time-periodic switching surface in the infinite-dimensional phase space. As the parameters of the linear structural behaviour of the tool/machine tool system can be obtained by means of standard modal testing, the developed numerical algorithm provides efficient support for the design of milling processes with quick estimates of those parameter domains where chatter can still appear in spite of setting the parameters into linearly stable domains. PMID:26303918

Intelligent complementary sliding-mode control for LUSMS-based X-Y-theta motion control stage.

PubMed

Lin, Faa-Jeng; Chen, Syuan-Yi; Shyu, Kuo-Kai; Liu, Yen-Hung

2010-07-01

An intelligent complementary sliding-mode control (ICSMC) system using a recurrent wavelet-based Elman neural network (RWENN) estimator is proposed in this study to control the mover position of a linear ultrasonic motors (LUSMs)-based X-Y-theta motion control stage for the tracking of various contours. By the addition of a complementary generalized error transformation, the complementary sliding-mode control (CSMC) can efficiently reduce the guaranteed ultimate bound of the tracking error by half compared with the slidingmode control (SMC) while using the saturation function. To estimate a lumped uncertainty on-line and replace the hitting control of the CSMC directly, the RWENN estimator is adopted in the proposed ICSMC system. In the RWENN, each hidden neuron employs a different wavelet function as an activation function to improve both the convergent precision and the convergent time compared with the conventional Elman neural network (ENN). The estimation laws of the RWENN are derived using the Lyapunov stability theorem to train the network parameters on-line. A robust compensator is also proposed to confront the uncertainties including approximation error, optimal parameter vectors, and higher-order terms in Taylor series. Finally, some experimental results of various contours tracking show that the tracking performance of the ICSMC system is significantly improved compared with the SMC and CSMC systems.

Multiradar tracking for theater missile defense

NASA Astrophysics Data System (ADS)

Sviestins, Egils

1995-09-01

A prototype system for tracking tactical ballistic missiles using multiple radars has been developed. The tracking is based on measurement level fusion (`true' multi-radar) tracking. Strobes from passive sensors can also be used. We describe various features of the system with some emphasis on the filtering technique. This is based on the Interacting Multiple Model framework where the states are Free Flight, Drag, Boost, and Auxiliary. Measurement error modeling includes the signal to noise ratio dependence; outliers and miscorrelations are handled in the same way. The launch point is calculated within one minute from the detection of the missile. The impact point, and its uncertainty region, is calculated continually by extrapolating the track state vector using the equations of planetary motion.

Evaluation of conventional and alternative monitoring methods for a recreational marine beach with nonpoint source of fecal contamination.

PubMed

Shibata, Tomoyuki; Solo-Gabriele, Helena M; Sinigalliano, Christopher D; Gidley, Maribeth L; Plano, Lisa R W; Fleisher, Jay M; Wang, John D; Elmir, Samir M; He, Guoqing; Wright, Mary E; Abdelzaher, Amir M; Ortega, Cristina; Wanless, David; Garza, Anna C; Kish, Jonathan; Scott, Troy; Hollenbeck, Julie; Backer, Lorraine C; Fleming, Lora E

2010-11-01

The objectives of this work were to compare enterococci (ENT) measurements based on the membrane filter, ENT(MF) with alternatives that can provide faster results including alternative enterococci methods (e.g., chromogenic substrate (CS), and quantitative polymerase chain reaction (qPCR)), and results from regression models based upon environmental parameters that can be measured in real-time. ENT(MF) were also compared to source tracking markers (Staphylococcus aureus, Bacteroidales human and dog markers, and Catellicoccus gull marker) in an effort to interpret the variability of the signal. Results showed that concentrations of enterococci based upon MF (<2 to 3320 CFU/100 mL) were significantly different from the CS and qPCR methods (p < 0.01). The correlations between MF and CS (r = 0.58, p < 0.01) were stronger than between MF and qPCR (r ≤ 0.36, p < 0.01). Enterococci levels by MF, CS, and qPCR methods were positively correlated with turbidity and tidal height. Enterococci by MF and CS were also inversely correlated with solar radiation but enterococci by qPCR was not. The regression model based on environmental variables provided fair qualitative predictions of enterococci by MF in real-time, for daily geometric mean levels, but not for individual samples. Overall, ENT(MF) was not significantly correlated with source tracking markers with the exception of samples collected during one storm event. The inability of the regression model to predict ENT(MF) levels for individual samples is likely due to the different sources of ENT impacting the beach at any given time, making it particularly difficult to to predict short-term variability of ENT(MF) for environmental parameters.

Particle Tracking Model for Suspended Sediment Transport and Streambed Clogging Under Losing and Gaining Conditions

NASA Astrophysics Data System (ADS)

Preziosi-Ribero, A.; Fox, A.; Packman, A. I.; Escobar-Vargas, J.; Donado-Garzon, L. D.; Li, A.; Arnon, S.

2017-12-01

Exchange of mass, momentum and energy between surface water and groundwater is a driving factor for the biology, ecology and chemistry of rivers and water bodies in general. Nonetheless, this exchange is dominated by different factors like topography, bed morphology, and large-scale hydraulic gradient. In the particular case of fine sediments like clay, conservative tracer modeling is impossible because they are trapped in river beds for long periods, thus the normal advection dispersion approach leads to errors and results do not agree with reality. This study proposes a numerical particle tracking model that represents the behavior of kaolinite in a sand flume, and how its deposition varies according to different flow conditions, namely losing and gaining flow. Since fine particles do not behave like solutes, kaolinite dynamics are represented using settling velocity and a filtration coefficient allowing the particles to be trapped in the bed. This approach allows us to use measurable parameters directly related with the fine particle features as size and shape, and hydraulic parameters. Results are then compared with experimental results from lab experiments obtained in a recirculating flume, in order to assess the impact of losing and gaining conditions on sediment transport and deposition. Furthermore, our model is able to identify the zones where kaolinite deposition concentrates over the flume due to the bed geometry, and later relate these results with clogging of the bed and hence changes in the bed's hydraulic conductivity. Our results suggest that kaolinite deposition is higher under losing conditions since the vertical velocity of the flow is added to the deposition velocity of the particles modeled. Moreover, the zones where kaolinite concentrates varies under different flow conditions due to the difference in pressure and velocity in the river bed.

The Superconducting Supercollider and US Science Policy

NASA Astrophysics Data System (ADS)

Marburger, John H.

2014-06-01

Reasons for the Superconducting Supercollider's (SSC's) termination include significant changes in the attitude of the government towards large scientific projects originating with management reforms introduced decades earlier. In the 1980s, the government insisted on inclusion of elements of these reforms in the SSC's management contract, including increased demands for accountability, additional liability for contractors, and sanctions for infractions. The SSC's planners could not have opted out of the reforms, which were by then becoming part of all large publicly funded projects. Once these reforms were in place, management mistakes in the SSC's planning and construction became highly visible, leading to termination of the machine. This episode contains two key lessons about science policy. One is that the momentum of the government's management reforms was unstoppable, and its impact on large scientific facilities and projects could not be reversed. The other is that specific measures such as cost and schedule-tracking systems to provide measures of program performance and impact were also inevitable; large scientific projects needed new parameters of accountability and transparency in what can be called the Principle of Assurance.

Display Provides Pilots with Real-Time Sonic-Boom Information

NASA Technical Reports Server (NTRS)

Haering, Ed; Plotkin, Ken

2013-01-01

Supersonic aircraft generate shock waves that move outward and extend to the ground. As a cone of pressurized air spreads across the landscape along the flight path, it creates a continuous sonic boom along the flight track. Several factors can influence sonic booms: weight, size, and shape of the aircraft; its altitude and flight path; and weather and atmospheric conditions. This technology allows pilots to control the impact of sonic booms. A software system displays the location and intensity of shock waves caused by supersonic aircraft. This technology can be integrated into cockpits or flight control rooms to help pilots minimize sonic boom impact in populated areas. The system processes vehicle and flight parameters as well as data regarding current atmospheric conditions. The display provides real-time information regarding sonic boom location and intensity, enabling pilots to make the necessary flight adjustments to control the timing and location of sonic booms. This technology can be used on current-generation supersonic aircraft, which generate loud sonic booms, as well as future- generation, low-boom aircraft, anticipated to be quiet enough for populated areas.

A Railway Track Geometry Measuring Trolley System Based on Aided INS

PubMed Central

Chen, Qijin; Niu, Xiaoji; Zuo, Lili; Zhang, Tisheng; Xiao, Fuqin; Liu, Yi; Liu, Jingnan

2018-01-01

Accurate measurement of the railway track geometry is a task of fundamental importance to ensure the track quality in both the construction phase and the regular maintenance stage. Conventional track geometry measuring trolleys (TGMTs) in combination with classical geodetic surveying apparatus such as total stations alone cannot meet the requirements of measurement accuracy and surveying efficiency at the same time. Accurate and fast track geometry surveying applications call for an innovative surveying method that can measure all or most of the track geometric parameters in short time without interrupting the railway traffic. We provide a novel solution to this problem by integrating an inertial navigation system (INS) with a geodetic surveying apparatus, and design a modular TGMT system based on aided INS, which can be configured according to different surveying tasks including precise adjustment of slab track, providing tamping measurements, measuring track deformation and irregularities, and determination of the track axis. TGMT based on aided INS can operate in mobile surveying mode to significantly improve the surveying efficiency. Key points in the design of the TGMT’s architecture and the data processing concept and workflow are introduced in details, which should benefit subsequent research and provide a reference for the implementation of this kind of TGMT. The surveying performance of proposed TGMT with different configurations is assessed in the track geometry surveying experiments and actual projects. PMID:29439423

Glassy dynamics in three-dimensional embryonic tissues

PubMed Central

Schötz, Eva-Maria; Lanio, Marcos; Talbot, Jared A.; Manning, M. Lisa

2013-01-01

Many biological tissues are viscoelastic, behaving as elastic solids on short timescales and fluids on long timescales. This collective mechanical behaviour enables and helps to guide pattern formation and tissue layering. Here, we investigate the mechanical properties of three-dimensional tissue explants from zebrafish embryos by analysing individual cell tracks and macroscopic mechanical response. We find that the cell dynamics inside the tissue exhibit features of supercooled fluids, including subdiffusive trajectories and signatures of caging behaviour. We develop a minimal, three-parameter mechanical model for these dynamics, which we calibrate using only information about cell tracks. This model generates predictions about the macroscopic bulk response of the tissue (with no fit parameters) that are verified experimentally, providing a strong validation of the model. The best-fit model parameters indicate that although the tissue is fluid-like, it is close to a glass transition, suggesting that small changes to single-cell parameters could generate a significant change in the viscoelastic properties of the tissue. These results provide a robust framework for quantifying and modelling mechanically driven pattern formation in tissues. PMID:24068179

Model-independent position domain sliding mode control for contour tracking of robotic manipulator

NASA Astrophysics Data System (ADS)

Yue, W. H.; Pano, V.; Ouyang, P. R.; Hu, Y. Q.

2017-01-01

In this paper, a new position domain feedback type sliding mode control (PDC-SMC) law is proposed for contour tracking control of multi-DOF (degree of freedom) nonlinear robotic manipulators focusing on the improvement of contour tracking performances. One feature of the proposed control law is its model-independent control scheme that can avoid calculation of the feedforward part in a standard SMC. The new control law takes the advantages of the high contour tracking performance of PD type feedback position domain control (PDC) and the robustness of SMC. Stability analysis is performed using the Lyapunov stability theory, and simulation studies are conducted to verify the effectiveness of the developed PDC-SMC control system. In addition, the effects of control parameters of the SMC on system performances are studied.

Robot trajectory tracking with self-tuning predicted control

NASA Technical Reports Server (NTRS)

Cui, Xianzhong; Shin, Kang G.

1988-01-01

A controller that combines self-tuning prediction and control is proposed for robot trajectory tracking. The controller has two feedback loops: one is used to minimize the prediction error, and the other is designed to make the system output track the set point input. Because the velocity and position along the desired trajectory are given and the future output of the system is predictable, a feedforward loop can be designed for robot trajectory tracking with self-tuning predicted control (STPC). Parameters are estimated online to account for the model uncertainty and the time-varying property of the system. The authors describe the principle of STPC, analyze the system performance, and discuss the simplification of the robot dynamic equations. To demonstrate its utility and power, the controller is simulated for a Stanford arm.

The Correlation of Arterial Stiffness with Biophysical Parameters and Blood Biochemistry.

PubMed

Khiyami, Anamil M; Dore, Fiona J; Mammadova, Aytan; Amdur, Richard L; Sen, Sabyasachi

2017-05-01

Type 2 diabetes presents with numerous macrovascular and microvascular impairments, which in turn lead to various co-morbidities. Vascular co-morbidities can be seen when examining arterial stiffness (AS), which is a predictor for endothelial health and cardiovascular disease risk. Pulse wave analysis (PWA) and pulse wave velocity (PWV) are two tests that are commonly used to measure AS. Currently, disease states and progression are tracked via blood biochemistry. These gold standards in monitoring diabetes are expensive and need optimization. To investigate which biophysical and biochemical parameters correlated best with AS, which may reduce the number of biochemical tests and biophysical parameter measurements needed to track disease progression. Data from 42 subjects with type 2 diabetes mellitus for ≤10 years, aged 40-70 years, were analyzed at a single time point. We investigated various blood biochemistry, body composition, and AS parameters. A combination of fat mass and fat-free mass was most associated with PWA over any other parameters. Leptin and high-sensitivity C-reactive protein seem to be the next two parameters that correlate with augmentation index. No other parameters had strong correlations to either PWA or PWV values. Body composition methods seemed to be better predictors of type 2 diabetes mellitus patient's vascular disease progression. Our study indicates that body composition measurements may help replace expensive tests. This may have public health and health surveillance implications in countries facing financial challenges.

Detection of Dry Intrusion on Water Vapor Images Over Central Europe - June 2010 TO September 2011

NASA Astrophysics Data System (ADS)

Novotny, J.; Dejmal, K.; Hudec, F.; Kolar, P.

2016-06-01

The knowledge of evaluation of the intensity of cyclogenesis which could be connected with the weather having a significant impact on Earth's surface is quite useful. If, as one of the basic assumptions, the existence of connection between dry intrusions, dry bands, tropopause height and warm dark areas distribution on water vapor images (WV images) is considered, it is possible to set up a method of detecting dry intrusions on searching and tracking areas with higher brightness temperature compared with the surrounding environment. This paper covers the period between June 2010 and September 2011 over Central Europe. The ISIS method (Instrument de Suivi dans I'Imagerie satellitaire), originally developed for detection of cold cloud tops, was used as an initial ideological point. Subsequently, this method was modified by Michel and Bouttier for usage on WV images. Some of the applied criteria and parameters were chosen with reference to the results published by Michel and Bouttier as well as by Novotny. The procedure can be divided into two steps: detection of warm areas and their tracking. Cases of detection of areas not evidently connected with dry intrusions can be solved by filtering off based on the connection between detected warm areas to the cyclonic side of jet streams and significant lowering of the tropopause.

Delirium, Frailty, and Fast-Track Surgery in Oncogeriatrics: Is There a Link?

PubMed Central

Monacelli, Fiammetta; Signori, Alessio; Prefumo, Matteo; Giannotti, Chiara; Nencioni, Alessio; Romairone, Emanuele; Scabini, Stefano; Odetti, Patrizio

2018-01-01

Background/Aims Postoperative delirium (POD) is more frequent in elderly patients undergoing major cancer surgery. The interplay between individual clinical vulnerability and a series of perioperative factors seems to play a relevant role. Surgery is the first-line treatment option for cancer, and fast-track surgery (FTS) has been documented to decrease postoperative complications. The study sought to assess, after comprehensive geriatric assessment (CGA) and frailty stratification (Rockwood 40 items index), which perioperative parameters were predictive of POD development in elderly patients undergoing FTS for colorectal cancer. Methods A total of 107 consecutive subjects admitted for elective colorectal FTS were enrolled. All patients underwent CGA, frailly stratification, Timed up & go (TUG) test, 4AT test for delirium screening, anesthesiologists physical status classification, and Dindo-Clavien classification. Results The incidence of POD was 12.3%. Patients’ prevalent clinical phenotype was pre-frail. The multivariate analysis indicated physical performance (TUG in seconds) as the most significant predictor of POD for each second of increase. Conclusions Only few procedure-specific studies have examined the impact of FTS for colorectal cancer on POD. This is the first study to investigate the risk factors for POD, in a vulnerable octogenarian oncogeriatric population submitted to FTS surgery and frailty stratification. PMID:29515621