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Sample records for fast surface based

  1. Raw data based image processing algorithm for fast detection of surface breaking cracks

    NASA Astrophysics Data System (ADS)

    Sruthi Krishna K., P.; Puthiyaveetil, Nithin; Kidangan, Renil; Unnikrishnakurup, Sreedhar; Zeigler, Mathias; Myrach, Philipp; Balasubramaniam, Krishnan; Biju, P.

    2017-02-01

    The aim of this work is to illustrate the contribution of signal processing techniques in the field of Non-Destructive Evaluation. A component's life evaluation is inevitably related to the presence of flaws in it. The detection and characterization of cracks prior to damage is a technologically and economically significant task and is of very importance when it comes to safety-relevant measures. The Laser Thermography is the most effective and advanced thermography method for Non-Destructive Evaluation. High capability for the detection of surface cracks and for the characterization of the geometry of artificial surface flaws in metallic samples of laser thermography is particularly encouraging. This is one of the non-contacting, fast and real time detection method. The presence of a vertical surface breaking crack will disturb the thermal footprint. The data processing method plays vital role in fast detection of the surface and sub-surface cracks. Currently in laser thermographic inspection lacks a compromising data processing algorithm which is necessary for the fast crack detection and also the analysis of data is done as part of post processing. In this work we introduced a raw data based image processing algorithm which results precise, better and fast crack detection. The algorithm we developed gives better results in both experimental and modeling data. By applying this algorithm we carried out a detailed investigation variation of thermal contrast with crack parameters like depth and width. The algorithm we developed is applied for various surface temperature data from the 2D scanning model and also validated credibility of algorithm with experimental data.

  2. Fast surface-based travel depth estimation algorithm for macromolecule surface shape description.

    PubMed

    Giard, Joachim; Alface, Patrice Rondao; Gala, Jean-Luc; Macq, Benoît

    2011-01-01

    Travel Depth, introduced by Coleman and Sharp in 2006, is a physical interpretation of molecular depth, a term frequently used to describe the shape of a molecular active site or binding site. Travel Depth can be seen as the physical distance a solvent molecule would have to travel from a point of the surface, i.e., the Solvent-Excluded Surface (SES), to its convex hull. Existing algorithms providing an estimation of the Travel Depth are based on a regular sampling of the molecule volume and the use of the Dijkstra's shortest path algorithm. Since Travel Depth is only defined on the molecular surface, this volume-based approach is characterized by a large computational complexity due to the processing of unnecessary samples lying inside or outside the molecule. In this paper, we propose a surface-based approach that restricts the processing to data defined on the SES. This algorithm significantly reduces the complexity of Travel Depth estimation and makes possible the analysis of large macromolecule surface shape description with high resolution. Experimental results show that compared to existing methods, the proposed algorithm achieves accurate estimations with considerably reduced processing times.

  3. Metadyn View: Fast web-based viewer of free energy surfaces calculated by metadynamics

    NASA Astrophysics Data System (ADS)

    Hošek, Petr; Spiwok, Vojtěch

    2016-01-01

    Metadynamics is a highly successful enhanced sampling technique for simulation of molecular processes and prediction of their free energy surfaces. An in-depth analysis of data obtained by this method is as important as the simulation itself. Although there are several tools to compute free energy surfaces from metadynamics data, they usually lack user friendliness and a build-in visualization part. Here we introduce Metadyn View as a fast and user friendly viewer of bias potential/free energy surfaces calculated by metadynamics in Plumed package. It is based on modern web technologies including HTML5, JavaScript and Cascade Style Sheets (CSS). It can be used by visiting the web site and uploading a HILLS file. It calculates the bias potential/free energy surface on the client-side, so it can run online or offline without necessity to install additional web engines. Moreover, it includes tools for measurement of free energies and free energy differences and data/image export.

  4. Fast disinfecting antimicrobial surfaces.

    PubMed

    Madkour, Ahmad E; Dabkowski, Jeffery M; Nusslein, Klaus; Tew, Gregory N

    2009-01-20

    Silicon wafers and glass surfaces were functionalized with facially amphiphilic antimicrobial copolymers using the "grafting from" technique. Surface-initiated atom transfer radical polymerization (ATRP) was used to grow poly(butylmethacrylate)-co-poly(Boc-aminoethyl methacrylate) from the surfaces. Upon Boc-deprotection, these surfaces became highly antimicrobial and killed S. aureus and E. coli 100% in less than 5 min. The molecular weight and grafting density of the polymer were controlled by varying the polymerization time and initiator surface density. Antimicrobial studies showed that the killing efficiency of these surfaces was independent of polymer layer thickness or grafting density within the range of surfaces studied.

  5. Fast Disinfecting Antimicrobial Surfaces

    PubMed Central

    Madkour, Ahmad E.; Dabkowski, Jeffery M.; Nüsslein, Klaus; Tew, Gregory N.

    2013-01-01

    Silicon wafers and glass surfaces were functionalized with facially amphiphilic antimicrobial copolymers using the “grafting from” technique. Surface initiated atom transfer radical polymerization (ATRP) was used to grow poly(butylmethacrylate)-co-poly(Boc-aminoethyl methacrylate) from the surfaces. Upon Boc-deprotection, these surfaces became highly antimicrobial and killed S. aureus and E. coli 100% in less than 5 min. The molecular weight and grafting density of the polymer were controlled by varying the polymerization time and initiator surface density. Antimicrobial studies showed that the killing efficiency of these surfaces was independent of polymer layer thickness or grafting density within the range of surfaces studied. PMID:19177651

  6. Fast simulation of x-ray projections of spline-based surfaces using an append buffer

    NASA Astrophysics Data System (ADS)

    Maier, Andreas; Hofmann, Hannes G.; Schwemmer, Chris; Hornegger, Joachim; Keil, Andreas; Fahrig, Rebecca

    2012-10-01

    Many scientists in the field of x-ray imaging rely on the simulation of x-ray images. As the phantom models become more and more realistic, their projection requires high computational effort. Since x-ray images are based on transmission, many standard graphics acceleration algorithms cannot be applied to this task. However, if adapted properly, the simulation speed can be increased dramatically using state-of-the-art graphics hardware. A custom graphics pipeline that simulates transmission projections for tomographic reconstruction was implemented based on moving spline surface models. All steps from tessellation of the splines, projection onto the detector and drawing are implemented in OpenCL. We introduced a special append buffer for increased performance in order to store the intersections with the scene for every ray. Intersections are then sorted and resolved to materials. Lastly, an absorption model is evaluated to yield an absorption value for each projection pixel. Projection of a moving spline structure is fast and accurate. Projections of size 640 × 480 can be generated within 254 ms. Reconstructions using the projections show errors below 1 HU with a sharp reconstruction kernel. Traditional GPU-based acceleration schemes are not suitable for our reconstruction task. Even in the absence of noise, they result in errors up to 9 HU on average, although projection images appear to be correct under visual examination. Projections generated with our new method are suitable for the validation of novel CT reconstruction algorithms. For complex simulations, such as the evaluation of motion-compensated reconstruction algorithms, this kind of x-ray simulation will reduce the computation time dramatically.

  7. Fast surface and volume rendering based on shear-warp factorization for a surgical simulator.

    PubMed

    Kim, Keun Ho; Kwon, Min Jeong; Kwon, Sung Min; Ra, Jong Beom; Park, HyunWook

    2002-01-01

    Fast simultaneous visualization of 3D medical images and medical instruments is necessary for a surgical simulator. Because unconstrained motion of a medical instrument is more frequent than that of the patient, the visualization of medical instruments is performed in real time using surface rendering. However, volume rendering is usually used for realistic visualization of the 3D medical image. We have developed an algorithm to combine a volume-rendered image and a surface-rendered image using a Z-buffer for depth cueing, which is applied to a surgical simulator. Surface rendering is used for visualization of a medical instrument, whereas 3D medical images such as CT and MRI are usually visualized by volume rendering, because segmentation of the medical image is difficult. In this study, when the volume-rendered image is combined with the surface-rendered image, the amount of computation is reduced by early ray termination and instrument-region masking in the sheared image space. Using these methods, a fast combination of volume-rendered and surface-rendered images is performed with high image quality. The method is appropriate for real-time visualization of 3D medical images and medical instrument motion in the images, and can be applied to image-guided therapy and surgical simulators.

  8. Fast time-of-flight camera based surface registration for radiotherapy patient positioning

    SciTech Connect

    Placht, Simon; Stancanello, Joseph; Schaller, Christian; Balda, Michael; Angelopoulou, Elli

    2012-01-15

    Purpose: This work introduces a rigid registration framework for patient positioning in radiotherapy, based on real-time surface acquisition by a time-of-flight (ToF) camera. Dynamic properties of the system are also investigated for future gating/tracking strategies. Methods: A novel preregistration algorithm, based on translation and rotation-invariant features representing surface structures, was developed. Using these features, corresponding three-dimensional points were computed in order to determine initial registration parameters. These parameters became a robust input to an accelerated version of the iterative closest point (ICP) algorithm for the fine-tuning of the registration result. Distance calibration and Kalman filtering were used to compensate for ToF-camera dependent noise. Additionally, the advantage of using the feature based preregistration over an ''ICP only'' strategy was evaluated, as well as the robustness of the rigid-transformation-based method to deformation. Results: The proposed surface registration method was validated using phantom data. A mean target registration error (TRE) for translations and rotations of 1.62 {+-} 1.08 mm and 0.07 deg. {+-} 0.05 deg., respectively, was achieved. There was a temporal delay of about 65 ms in the registration output, which can be seen as negligible considering the dynamics of biological systems. Feature based preregistration allowed for accurate and robust registrations even at very large initial displacements. Deformations affected the accuracy of the results, necessitating particular care in cases of deformed surfaces. Conclusions: The proposed solution is able to solve surface registration problems with an accuracy suitable for radiotherapy cases where external surfaces offer primary or complementary information to patient positioning. The system shows promising dynamic properties for its use in gating/tracking applications. The overall system is competitive with commonly-used surface

  9. Sputtering of fast meteoroids' surface

    NASA Astrophysics Data System (ADS)

    Popova, O. P.; Strelkov, A. S.; Sidneva, S. N.

    Entering meteoroids are subjected by direct impacts of molecules of the individual constituents of the air, when the body approaching the Earth at heights of about 300-100 km. At meteor velocities about 72 km/s the energy of air molecules is about 800 eV and oxygen atoms have energy about 400 eV. Particles with such energies don't penetrate into deep layers of entering body and are concentrated in narrow surface layer of about hundreds angstroms. Action of air particles on meteoroid leads to both heating of meteoroid and sputtering of meteoroid surface. Sputtering effect was supposed as explanation of this high altitude ionization and luminosity (Brosch et al, 2001), which aren't explained by classical ablation theory. Sputtering results in appearance of fast particles, which also may be exited and/or ionized. Flux of these particles causes formation of ionized meteor trails recording by radars. For bigger bodies fast particles may create luminous area at the altitudes above altitude of intensive evaporation. We demonstrate physical model, which allows us to describe sputtering of meteoroid surface under impacts of incoming air particles. We consider sputtering of meteoroid with composition close to hondritic one at the altitude 150 km. Fast particles are really sputtered from meteoroid surface. They carry out about 10% of incoming flux energy. There are also reflected particles, but the most part of total particle outcome is formed by particles of meteor substance. Presence of fast particles possibly explains a large size of meteors in diffuse stage at high altitudes (above 130 km). The sputtering is neglectable in the case of meteor velocities below 30 km/s. Sputtered and reflected particles have enough high ionization degree (˜ (1-5) 10-2, that is larger than ionization degree of surrounding atmosphere (˜ 10-5div 10-6)).

  10. Manybeam velocimeter for fast surfaces

    SciTech Connect

    Goosman, D.; Avara, G.; Steinmetz, L.; Lai, C.; Perry, S.

    1996-09-01

    For the past 5 years, we have conceived, built and successfully used a new 10 beam laser velocimeter for monitoring velocity vs time histories of fast moving surfaces, and will have a 20 beam capability soon. We conceived a method to multiplex 5 to 10 beams through a single Fabry-Perot interferometer, without losing any light that our equivalently-performing single beam system could use, and with negligible cross- talk. This saves the cost of 16 interferometers, simplifies operation and takes less space than without multiplexing. We devised special efficient light collecting probes, streak cameras that change sweep speed during the course of the record, and a new double cavity interferometer which is better, cheaper and more flexible than our previous versions. With the 10 recorders, we conceived and employ a method of using both a fast and a slow streak camera on each of 5 beams without reducing the light that is available to either camera separately. Five new galvanometrically-driven triggerable CCD streak cameras will be installed soon.

  11. Fast evaluation of surface sensitivity on ghost

    NASA Astrophysics Data System (ADS)

    Boehme, Beate

    2015-09-01

    Real optical systems are often suffering from false light caused by ghosts. In particular single reflections are critical in applications like reflected light illumination microscopy or confocal systems. The degradations of performance can be bright spots in the image or contrast, signal to noise or dynamic range reduction. Thus in these systems the suppression of first order reflections is important. State of the art optical design software supports ray trace based ghost image analysis. The automatic generation of reflex light paths is provided, but for systems with a large number of surfaces the analysis of all ghost light paths is time-consuming. Conventional Monte Carlo based non sequential ray trace sums up the reflections of all surfaces simultaneously. To achieve high accuracy a huge number of rays is necessary, what results in long computational time, especially if the distinction of surface influences needs multiple calculations. In this paper a fast method is proposed for the ranking of ghosts. It was developed for single reflections in centered optical systems. For each surface the ghost light path is calculated with paraxial and real ray trace. The ghost diameter and the corresponding illumination NA are calculated. Usually the distance of the reflex focus to the image is used as criterion to access the importance of a ghost. Here we use the power of the ghost ray bundle. It is compared with the signal strength and listed for all surfaces generating a ghost. So in one step a surface contribution of reflex powers as well as an estimation of total flux of reflected light is obtained. Due to the fact, that only a few rays have to be calculated, the method is rather fast. The accuracy can be estimated by comparison of paraxial and marginal ray trace. In the proposed method, some assumptions and approximations are made. They are assessed in respect to some practical examples, and by comparison with full brute force non-sequential ray trace. The usefulness of

  12. Characterization and simulation of fast neutron detectors based on surface-barrier VPE GaAs structures with polyethylene converter

    NASA Astrophysics Data System (ADS)

    Chernykh, A. V.; Chernykh, S. V.; Baryshnikov, F. M.; Didenko, S. I.; Burtebayev, N.; Britvich, G. I.; Kostin, M. Yu.; Chubenko, A. P.; Nassurlla, Marzhan; Nassurlla, Maulen; Kerimkulov, Zh.; Zholdybayev, T.; Glybin, Yu. N.; Sadykov, T. Kh.

    2016-12-01

    Fast neutron detectors with an active area of 80 mm2 based on surface-barrier VPE GaAs structures were fabricated and tested. Polyethylene with density of 0.90 g/cm3 was used as a converter layer. The recoil-proton surface-barrier sensor was fabricated on high purity VPE GaAs epilayers with a thickness of 50 μm. The neutron detection efficiency measured with a 241Am-Be source was 1.30 · 10-3 puls./neutr. for the PE converter thickness of 670 μm. The signal-to-gamma-background ratio was at the level of 50. Simulation of the detector characteristics with Geant4 toolkit has showed good correlation with the experimental data and allowed to estimate the maximal theoretical detection efficiency of the detector which is determined by the PE converter and equals to 1.37 · 10-3 puls./neutr. The difference between the measured and simulated values of the detection efficiency is due to the fact that the events with energies below 0.5 MeV were not taken into account during the measurements.

  13. A laser probe based on a Sagnac interferometer with fast mechanical scan for RF surface and bulk acoustic wave devices.

    PubMed

    Hashimoto, Ken-ya; Kashiwa, Keiskue; Wu, Nan; Omori, Tatsuya; Yamaguchi, Masatsune; Takano, Osamu; Meguro, Sakae; Akahane, Koichi

    2011-01-01

    This paper describes the development of a phasesensitive laser probe with fast mechanical scan for RF surface and bulk acoustic wave (SAW/BAW) devices. The Sagnac interferometer composed of micro-optic elements was introduced for the selective detection of RF vertical motion associated with RF SAW/BAW propagation and vibration. A high-pass characteristic of the interferometer makes the measurement very insensitive to low-frequency vibration. This feature allows us to apply the fast mechanical scan to the interferometric measurement without badly sacrificing its SNR and spatial resolution. The system was applied to the visualization of a field pattern on the vibrating surface of an RF BAW resonator operating in the 2 GHz range. The field pattern was obtained in 17 min as a 2-D image (500 × 750 pixel with 0.4 μm resolution and SNR of 40 dB). The system was also applied to the characterization of an RF SAW resonator operating in the 1 GHz range, and the applicability of the system was demonstrated.

  14. Fast nucleotide identification through fingerprinting using gold nanoparticle-based surface-assisted laser desorption/ionisation.

    PubMed

    Larguinho, Miguel; Capelo, José L; Baptista, Pedro V

    2013-02-15

    We report a method centred on gold nanoparticle-based surface-assisted laser desorption/ionisation for analysis of deoxynucleotides and alkylated nucleobases. Gold nanoparticles allow for enhanced analysis capability by eliminating undesired signature peaks; thus more elegant mass spectra can be attained that allow identification by nucleotide mass fingerprint. The resulting fingerprinting patterns on the spectra are compared and associated with the presence of different nucleotides in the sample. This method can be easily extended to modified nucleotides implicated in genome lesions due to exposure to environment chemicals, such as DNA adducts (e.g. guanine adducts). The use of gold nanoparticles for surface-assisted laser desorption/ionisation can be an useful tool to resolve common issues of background noise when analysing nucleic acids samples.

  15. Fast liquid transfer between two surfaces

    NASA Astrophysics Data System (ADS)

    Chen, Huanchen; Tang, Tian; Amirfazli, Alidad

    2014-11-01

    Liquid transfer process between two surfaces typically ends by breaking of a stretched liquid bridge. The amount of liquid remaining on each of the surfaces relative to total volume is usually of interest in applications (e.g. offset or electronic printing, wet adhesion systems, etc.). Literature shows that depending on stretching velocity, U, surface wettability and liquid properties, the behaviour of the liquid bridge can be categorized into: quasi-static where the surface force dominates and dynamic where contributions from viscous and inertia forces are not negligible. Through a systematic experimental study, we demonstrate for the first time that the division of liquid between surfaces in the quasi-static regime is a constant which depends on the receding contact angles. In the dynamic regime (fast transfer), liquid division takes a complicated form. An analytical-empirical model is developed and verified by experimental results that can predict splitting of the liquid between two surfaces as a function of U, surface wettability and liquid viscosity. The model also successfully predicts an even split between surfaces at extremely high velocities as it was observed by us and others.

  16. Decoherence in fast atom diffraction from surfaces

    NASA Astrophysics Data System (ADS)

    Bundaleski, N.; Soulisse, P.; Momeni, A.; Khemliche, H.; Roncin, P.

    2011-06-01

    Diffraction of fast atoms from crystal surfaces at grazing incidence (GIFAD) has now been observed on all types of materials, from wide band gap insulators to metals, including semiconductors. Since mainly the (slow) motion normal to the surface is important diffraction patterns are comparable to those obtained in thermal energies atomic diffraction (TEAS), however, the specific scattering geometry of GIFAD has a strong influence on decoherence phenomena. The contribution of atomic vibrations is much less pronounced than in TEAS but other sources of decoherence such as electronic excitations, clearly observed on metals, can participate due to the comparatively large projectile velocity parallel to the surface. We present here simple models that describe these decoherence effects. The results are in good agreement with the experimental results.

  17. Fast incorporation of primary amine group into polylactide surface for improving C₂C₁₂ cell proliferation using nitrogen-based atmospheric-pressure plasma jets.

    PubMed

    Yang, Yi-Wei; Wu, Jane-Yii; Liu, Chih-Tung; Liao, Guo-Chun; Huang, Hsuan-Yu; Hsu, Ray-Quen; Chiang, Ming-Hung; Wu, Jong-Shinn

    2014-01-01

    In this article, we report the development of the fast incorporation of primary amine functional groups into a polylactide (PLA) surface using the post-discharge jet region of an atmospheric-pressure nitrogen-based dielectric barrier discharge (DBD). Plasma treatments were carried out in two sequential steps: (1) nitrogen with 0.1% oxygen addition, and (2) nitrogen with 5% ammonia addition. The analyses show that the concentration of N/C ratio, surface energy, contact angle, and surface roughness of the treated PLA surface can reach 19.1%, 70.5 mJ/m(2), 38° and 73.22 nm, respectively. In addition, the proposed two-step plasma treatment procedure can produce a PLA surface exhibiting almost the same C2C12 cell attachment and proliferation performance as that of the conventional gelatin coating method. Most importantly, the processing/preparation time is reduced from 13-15 h (gelatin coating method) to 5-15 min (two-step plasma treatment), which is very useful in practical applications.

  18. Fast Surface Dynamics of Metallic Glass Enable Superlatticelike Nanostructure Growth

    NASA Astrophysics Data System (ADS)

    Chen, L.; Cao, C. R.; Shi, J. A.; Lu, Z.; Sun, Y. T.; Luo, P.; Gu, L.; Bai, H. Y.; Pan, M. X.; Wang, W. H.

    2017-01-01

    Contrary to the formation of complicated polycrystals induced by general crystallization, a modulated superlatticelike nanostructure, which grows layer by layer from the surface to the interior of a Pd40Ni10Cu30P20 metallic glass, is observed via isothermal annealing below the glass transition temperature. The generation of the modulated nanostructure can be solely controlled by the annealing temperature, and it can be understood based on the fast dynamic and liquidlike behavior of the glass surface. The observations have implications for understanding the glassy surface dynamics and pave a way for the controllable fabrication of a unique and sophisticated nanostructure on a glass surface to realize the properties' modification.

  19. Effects of surface wettability on fast liquid transfer

    NASA Astrophysics Data System (ADS)

    Chen, H.; Tang, T.; Amirfazli, A.

    2015-11-01

    A systematic experimental study was performed to understand the role of surface contact angles in affecting the process of fast liquid transfer. Surfaces with different wettabilities were used, and the transfer ratio (α, the amount of liquid transferred to the acceptor surface over the total amount of liquid) was measured for each pair of surfaces. A numerical model based on the volume of fluid method was developed to help understand the experimental results. The surface wettability was shown to significantly affect the boundaries between three regimes based on stretching speeds: quasi-static (surface force dominated), transition (surface/viscous/inertia forces all important) and dynamic (viscous/inertia forces dominated). Specifically, the values of the boundary speeds were found to increase with |α0 - 0.5|, where α0 is the transfer ratio in the quasi-static regime, and α0 is governed by the surface receding contact angles. Based on our results, an empirical equation to describe the transfer ratio as function of stretching speed was proposed. This equation can also be used as a prediction tool for the value of α for a fast transfer system.

  20. In situ fast ellipsometric analysis of repetitive surface phenomena

    NASA Astrophysics Data System (ADS)

    Costa, J.; Campmany, J.; Canillas, A.; Andújar, J. L.; Bertran, E.

    1997-08-01

    We present an ellipsometric technique and ellipsometric analysis of repetitive phenomena, based on the experimental arrangement of conventional phase modulated ellipsometers (PME) conceived to study fast surface phenomena in repetitive processes such as periodic and triggered experiments. Phase modulated ellipsometry is a highly sensitive surface characterization technique that is widely used in the real-time study of several processes such as thin film deposition and etching. However, fast transient phenomena cannot be analyzed with this technique because precision requirements limit the data acquisition rate to about 25 Hz. The presented new ellipsometric method allows the study of fast transient phenomena in repetitive processes with a time resolution that is mainly limited by the data acquisition system. As an example, we apply this new method to the study of surface changes during plasma enhanced chemical vapor deposition of amorphous silicon in a modulated radio frequency discharge of SiH4. This study has revealed the evolution of the optical parameters of the film on the millisecond scale during the plasma on and off periods. The presented ellipsometric method extends the capabilities of PME arrangements and permits the analysis of fast surface phenomena that conventional PME cannot achieve.

  1. Inversion of surface parameters using fast learning neural networks

    NASA Technical Reports Server (NTRS)

    Dawson, M. S.; Olvera, J.; Fung, A. K.; Manry, M. T.

    1992-01-01

    A neural network approach to the inversion of surface scattering parameters is presented. Simulated data sets based on a surface scattering model are used so that the data may be viewed as taken from a completely known randomly rough surface. The fast learning (FL) neural network and a multilayer perceptron (MLP) trained with backpropagation learning (BP network) are tested on the simulated backscattering data. The RMS error of training the FL network is found to be less than one half the error of the BP network while requiring one to two orders of magnitude less CPU time. When applied to inversion of parameters from a statistically rough surface, the FL method is successful at recovering the surface permittivity, the surface correlation length, and the RMS surface height in less time and with less error than the BP network. Further applications of the FL neural network to the inversion of parameters from backscatter measurements of an inhomogeneous layer above a half space are shown.

  2. Using compute unified device architecture-enabled graphic processing unit to accelerate fast Fourier transform-based regression Kriging interpolation on a MODIS land surface temperature image

    NASA Astrophysics Data System (ADS)

    Hu, Hongda; Shu, Hong; Hu, Zhiyong; Xu, Jianhui

    2016-04-01

    Kriging interpolation provides the best linear unbiased estimation for unobserved locations, but its heavy computation limits the manageable problem size in practice. To address this issue, an efficient interpolation procedure incorporating the fast Fourier transform (FFT) was developed. Extending this efficient approach, we propose an FFT-based parallel algorithm to accelerate regression Kriging interpolation on an NVIDIA® compute unified device architecture (CUDA)-enabled graphic processing unit (GPU). A high-performance cuFFT library in the CUDA toolkit was introduced to execute computation-intensive FFTs on the GPU, and three time-consuming processes were redesigned as kernel functions and executed on the CUDA cores. A MODIS land surface temperature 8-day image tile at a resolution of 1 km was resampled to create experimental datasets at eight different output resolutions. These datasets were used as the interpolation grids with different sizes in a comparative experiment. Experimental results show that speedup of the FFT-based regression Kriging interpolation accelerated by GPU can exceed 1000 when processing datasets with large grid sizes, as compared to the traditional Kriging interpolation running on the CPU. These results demonstrate that the combination of FFT methods and GPU-based parallel computing techniques greatly improves the computational performance without loss of precision.

  3. Fast and Efficient Approach in Surface Wave Analysis

    NASA Astrophysics Data System (ADS)

    Kanli, A. I.

    2010-12-01

    Fast and Efficient Approach in Surface Wave Analysis Ali Ismet KANLI Istanbul University, Engineering Faculty, Department of Geophysical Engineering, 34320, Avcilar Campus, Istanbul-Turkey, E-mail: kanli@istanbul.edu.tr Abstract: A two-step surface wave analysis method is proposed including both the MASW (Multi-channel Analysis of Surface Waves) and Micro-tremor based techniques. This is an integrated approach and the MASW survey data are gathered to obtain the shear wave velocity-depth information up to at least 30 meters by using a special type active seismic source called as SR-II or Kangaroo. In the second step, the microtremor data which are based on surface waves from seismic noise at each site are used to determine the shear-wave velocity-depth profiles. In the second step of the process, the multichannel analysis of surface waves data are given as constraints in the microtremor inversion process. This proposed algorithm allows us to calculate shear wave velocity-depth information with all geotechnical parameters from near surface to bedrock depths very fast and efficiently.

  4. Study of surface energy budget and test of a newly developed fast photoacoustic spectroscopy based hygrometer in field campaign Szeged (Hungary)

    NASA Astrophysics Data System (ADS)

    Tatrai, David; Nikov, Daniella; Zsolt Jász, Ervin; Bozóki, Zoltán; Szabó, Gábor; Weidinger, Tamás; András Gyöngyösi, Zénó; Kiss, Melinda; Józsa, János; Simó Diego, Gemma; Cuxart Rodamilans, Joan; Wrenger, Burkhart; Bottyán, Zsolt

    2014-05-01

    A micrometeorological field measurement campaign dedicated to study the surface energy budget and the structure of the boundary layer focusing on the transient layer forming periods during night-time was organized in the period of 10th of November to 3rd of December 2013 in the nearby of Szeged, Hungary. A temporary micrometeorological measurement station was set up at the coordinates N:46.239943; E:20.089758, approximately 1700 m far from a national meteorology station (N:46.255711; E:20.09052). In the experimental micrometeorological site different types of instruments were installed to measure numerous parameters: standard meteorological measurements (p, T, wet, wind speed and direction at three different levels, relative humidity at two levels and absolute humidity at one level) radiation budget components surface temperature and leaf wetness soil temperature, moisture and heat flux into the deeper soil layer eddy-covariance measurements (t, H, LE CO2) at 3 m level using Campbell open-path IRGA (EC150) system. At the national meteorology station (http://adatok.geo.u-szeged.hu/?lang=eng) besides their standard measurement equipment and measurement routine a SODAR was installed and continuously operated. These ground based measurements were combined with and supported by UAV, quadcopter and tethered balloon based vertical profile measurements of p, T, rh. For this measurement campaign as a modification of a previously developed airborne ready dual channel hygrometer, a fast photoacoustic spectroscopy based hygrometer was developed for absolute humidity measurements. The estimated response time of the system is faster than 15 Hz, which was achieved by the replacement of the data acquisition system and by recording the raw photoacoustic signal sampled at rate of 48 kHz for post-processing. During the campaign this new system was compared to a TDL system commercially available at Li-COR Inc. Besides the testing of the newly developed fast photoacoustic hygrometer

  5. Quantum interference of fast atoms scattered off crystal surfaces

    NASA Astrophysics Data System (ADS)

    Gravielle, M. S.

    2015-01-01

    The striking observation of interference structures produced by grazing impact of fast atoms on crystal surfaces reported a few years ago [1,2] has given rise to the development of a powerful surface analysis technique. This article gives a brief account of the main features of the process, using the Surface Eikonal (SE) approximation as a theoretical tool to analyze the different mechanisms responsible for the quantum interference. The SE approach is a semiclassical method based on the use of the eikonal wave function, which takes into account the coherent superposition of transition amplitudes for different axially channeled trajectories. It has proved to provide a quite good description of experimental diffraction patterns for different collision systems.

  6. Method for Accurate Surface Temperature Measurements During Fast Induction Heating

    NASA Astrophysics Data System (ADS)

    Larregain, Benjamin; Vanderesse, Nicolas; Bridier, Florent; Bocher, Philippe; Arkinson, Patrick

    2013-07-01

    A robust method is proposed for the measurement of surface temperature fields during induction heating. It is based on the original coupling of temperature-indicating lacquers and a high-speed camera system. Image analysis tools have been implemented to automatically extract the temporal evolution of isotherms. This method was applied to the fast induction treatment of a 4340 steel spur gear, allowing the full history of surface isotherms to be accurately documented for a sequential heating, i.e., a medium frequency preheating followed by a high frequency final heating. Three isotherms, i.e., 704, 816, and 927°C, were acquired every 0.3 ms with a spatial resolution of 0.04 mm per pixel. The information provided by the method is described and discussed. Finally, the transformation temperature Ac1 is linked to the temperature on specific locations of the gear tooth.

  7. Ultra-fast boriding of metal surfaces for improved properties

    SciTech Connect

    Timur, Servet; Kartal, Guldem; Eryilmaz, Osman L.; Erdemir, Ali

    2015-02-10

    A method of ultra-fast boriding of a metal surface. The method includes the step of providing a metal component, providing a molten electrolyte having boron components therein, providing an electrochemical boriding system including an induction furnace, operating the induction furnace to establish a high temperature for the molten electrolyte, and boriding the metal surface to achieve a boride layer on the metal surface.

  8. A fast pairwise evaluation of molecular surface area.

    PubMed

    Vasilyev, Vladislav; Purisima, Enrico O

    2002-05-01

    A fast and general analytical approach was developed for the calculation of the approximate van der Waals and solvent-accessible surface areas. The method is based on three basic ideas: the use of the Lorentz transformation formula, a rigid-geometry approximation, and a single fitting parameter that can be refitted on the fly during a simulation. The Lorentz transformation equation is used for the summation of the areas of an atom buried by its neighboring contacting atoms, and implies that a sum of the buried pairwise areas cannot be larger than the surface area of the isolated spherical atom itself. In a rigid-geometry approximation we numerically calculate and keep constant the surface of each atom buried by the atoms involved in 1-2 and 1-3 interactions. Only the contributions from the nonbonded atoms (1-4 and higher interactions) are considered in terms of the pairwise approximation. The accuracy and speed of the method is competitive with other pairwise algorithms. A major strength of the method is the ease of parametrization.

  9. Fast Liquid Transfer between Surfaces: Breakup of Stretched Liquid Bridges.

    PubMed

    Chen, H; Tang, T; Amirfazli, A

    2015-10-27

    In this work, a systematic experimental study was performed to understand the fast liquid transfer process between two surfaces. According to the value of the Reynolds number (Re), the fast transfer is divided into two different scenarios, one with negligible inertia effects (Re ≪ 1) and the other with significant inertia effects (Re > 1). For Re ≪ 1, the influences of the capillary number (Ca) and the dimensionless minimum separation (H(min)* = H(min)/V(1/3), where H(min) is the minimum separation between two surfaces and V is the volume of liquid) on the transfer ratio (α, the volume of liquid transferred to the acceptor surface over the total liquid volume) are discussed. On the basis of the roles of each physical parameter, an empirical equation is presented to predict the transfer ratio, α = f(Ca). This equation involves two coefficients which are affected only by the surface contact angles and H(min)* but not by the liquid viscosity or surface tension. When Re > 1, it is shown for the first time that the transfer ratio does not converge to 0.5 with the increase in the stretching speed.

  10. Fast response and low power consumption 1×2 thermo-optic switch based on dielectric-loaded surface plasmon polariton waveguides

    NASA Astrophysics Data System (ADS)

    Qi, Zhipeng; Hu, Guohua; Yun, Binfeng; Zhang, Xiong; Cui, Yiping

    2016-08-01

    In this paper, we present a 1 × 2 thermo-optic (TO) switch based on the integration of the dielectric-loaded surface plasmon polariton (SPP) waveguides with the silicon nanowires. Liquid-curable fluorinated resin (LFR) made of perfluorinated polymer was adopted as the ridge, which has a TO coefficient twice more than that of polymethyl methacrylate, leading to a significant decrease in the power consumption. It was shown that the response time of the dielectric-loaded SPP waveguide could be improved through optimizing the dimensions of the LFR polymer ridge without loss of relative high figure of merit and large confinement factor. Performance characteristics of such a 1 × 2 TO switch operating at a telecom wavelength of 1550 nm was investigated theoretically from the analysis of both heat and optical fields. The results reveal that a switching power as low as 7 mW and an extremely short switching time (with rise time of 3 μs and fall time of 6.7 μs) could be achieved with the proposed dielectric-loaded SPP-based 1 × 2 TO switch. In addition, the crosstalk could be enhanced to at least 40 dB with the applied power of 7 mW at the wavelength of 1550 nm, and it could be retained to be above 20 dB in the wavelength spectrum of 1500-1600 nm during the on/off state.

  11. A fast and efficient adaptive parallel ray tracing based model for thermally coupled surface radiation in casting and heat treatment processes

    NASA Astrophysics Data System (ADS)

    Fainberg, J.; Schaefer, W.

    2015-06-01

    A new algorithm for heat exchange between thermally coupled diffusely radiating interfaces is presented, which can be applied for closed and half open transparent radiating cavities. Interfaces between opaque and transparent materials are automatically detected and subdivided into elementary radiation surfaces named tiles. Contrary to the classical view factor method, the fixed unit sphere area subdivision oriented along the normal tile direction is projected onto the surrounding radiation mesh and not vice versa. Then, the total incident radiating flux of the receiver is approximated as a direct sum of radiation intensities of representative “senders” with the same weight factor. A hierarchical scheme for the space angle subdivision is selected in order to minimize the total memory and the computational demands during thermal calculations. Direct visibility is tested by means of a voxel-based ray tracing method accelerated by means of the anisotropic Chebyshev distance method, which reuses the computational grid as a Chebyshev one. The ray tracing algorithm is fully parallelized using MPI and takes advantage of the balanced distribution of all available tiles among all CPU's. This approach allows tracing of each particular ray without any communication. The algorithm has been implemented in a commercial casting process simulation software. The accuracy and computational performance of the new radiation model for heat treatment, investment and ingot casting applications is illustrated using industrial examples.

  12. Module for dielectric surfaces modification by fast neutral particles beams

    NASA Astrophysics Data System (ADS)

    Barchenko, V. T.; Lisenkov, A. A.; Babinov, N. A.

    2014-11-01

    In this paper, we describe the module for dielectric and wide-gap semiconductor surfaces modification by fast neutral beam. The module can be used for cleaning, etching or assisting of films deposition. The surface proceeding by neutral beam can prevent an accumulation of surface charge without using current compensation by inserting electrons to the beam or RF power supply. The module beside cathode and anode contains an electrode with floating potential. Insertion of the additional electrode causes electron retention in an electrostatic trap resulting the reducing of the module operating pressure. Moreover, the electrode with floating potential allows increasing the current efficient of the module. An important feature of the module is that neutralization of the ions extracted from the plasma occurs in the cathode potential well. Thereby ions that have not neutralized cannot leave nearcathode region and there are no fast ions in the output beam. Module does not contain sources of the magnetic fields or elements heated by external sources. Module operates with free cooling. Thus, the module does not need water cooling and can be freely moved in the vacuum chamber.

  13. Facile and fast fabrication of superhydrophobic surface on magnesium alloy

    NASA Astrophysics Data System (ADS)

    Wang, Zhongwei; Li, Qing; She, Zuxin; Chen, Funan; Li, Longqin; Zhang, Xiaoxu; Zhang, Peng

    2013-04-01

    Superhydrophobic surface has many special functions and is widely investigated by researchers. Magnesium alloy is one of the lightest metal materials among the practice metals. It plays an important role in automobile, airplane and digital product for reducing devices weight. But due to the low standard potential, magnesium alloy has a high chemical activity and easily be corroded. That seriously impedes the application of magnesium alloy. In the process of fabrication a superhydrophobic surface on magnesium alloy, there are two ineluctable problems that must be solved: (1) high chemical activity and (2) the chemical activity is inhomogeneous on surface. In this study, we solved those problems by using the two characters to gain a rough surface on magnesium alloy and obtained a superhydrophobic surface after following modification process. The results show that the as-prepared superhydrophobic surface has obvious anti-corrosion effect in typically corrosive solution and naturally humid air. The delay-icing and self-cleaning effects are also investigated. The presented method is low-cost, fast and has great potential value in large-scale industry production.

  14. Hyper fast radiative transfer for the physical retrieval of surface parameters from SEVIRI observations

    NASA Astrophysics Data System (ADS)

    Liuzzi, G.; Masiello, G.; Serio, C.; Blasi, M. G.; Venafra, S.

    2015-09-01

    This paper describes the theoretical aspects of a fast scheme for the physical retrieval of surface temperature and emissivity from SEVIRI data, their implementation and some sample results obtained. The scheme is based on a Kalman Filter approach, which effectively exploits the temporal continuity in the observations of the geostationary Meteosat Second Generation (MSG) platform, on which SEVIRI (Spinning Enhanced Visible and InfraRed Imager) operates. Such scheme embodies in its core a physical retrieval algorithm, which employs an hyper fast radiative transfer code highly customized for this retrieval task. Radiative transfer and its customizations are described in detail. Fastness, accuracy and stability of the code are fully documented for a variety of surface features, showing a peculiar application to the massive Greek forest fires in August 2007.

  15. Fast and Slow Wetting Dynamics on nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Nandyala, Dhiraj; Rahmani, Amir; Cubaud, Thomas; Colosqui, Carlos

    2015-11-01

    This talk will present force-displacement and spontaneous drop spreading measurements on diverse nanostructured surfaces (e.g., mesoporous titania thin films, nanoscale pillared structures, on silica or glass substrates). Experimental measurements are performed for water-air and water-oil systems. The dynamics of wetting observed in these experiments can present remarkable crossovers from fast to slow or arrested dynamics. The emergence of a slow wetting regime is attributed to a multiplicity of metastable equilibrium states induced by nanoscale surface features. The crossover point can be dramatically advanced or delayed by adjusting specific physical parameters (e.g., viscosity of the wetting phases) and geometric properties of the surface nanostructure (e.g., nanopore/pillar radius and separation). Controlling the crossover point to arrested dynamics can effectively modify the degree of contact angle hysteresis and magnitude of liquid adhesion forces observed on surfaces of different materials. This work is supported by a SEED Award from The Office of Brookhaven National Laboratory Affairs at Stony Brook University.

  16. Surface Plasmon Based Spectrometer

    NASA Astrophysics Data System (ADS)

    Wig, Andrew; Passian, Ali; Boudreaux, Philip; Ferrell, Tom

    2008-03-01

    A spectrometer that uses surface plasmon excitation in thin metal films to separate light into its component wavelengths is described. The use of surface plasmons as a dispersive medium sets this spectrometer apart from prism, grating, and interference based variants and allows for the miniaturization of this device. Theoretical and experimental results are presented for two different operation models. In the first case surface plasmon tunneling in the near field is used to provide transmission spectra of different broad band-pass, glass filters across the visible wavelength range with high stray-light rejection at low resolution as well as absorption spectra of chlorophyll extracted from a spinach leaf. The second model looks at the far field components of surface plasmon scattering.

  17. A flexible fast 3D profilometry based on modulation measurement

    NASA Astrophysics Data System (ADS)

    Dou, Yunfu; Su, Xianyu; Chen, Yanfei; Wang, Ying

    2011-03-01

    This paper proposes a flexible fast profilometry based on modulation measurement. Two orthogonal gratings through a beam splitter are vertically projected on an object surface, and the measured object is placed between the imaging planes of the two gratings. Then the image of the object surface modulated by the orthogonal gratings can be obtained by a CCD camera in the same direction as the grating projection. This image is processed by the operations consisting of performing the Fourier transform, spatial frequency filtering and inverse Fourier transform. Using the modulation distributions of two grating patterns, we can reconstruct the 3D shape of the object. In the measurement process, we only need to capture one fringe pattern, so it is faster than the MMP and remains the advantages of it. In the article, the principle of this method, the setup of the measurement system, some simulations and primary experiment results are given. The simulative and experimental result proves it can restore the 3D shape of the complex object fast and comparatively accurate. Because only one fringe pattern is needed in the testing, our method has a promising extensive application prospect in real-time acquiring and dynamic measurement of 3D data of complex objects.

  18. Fast imaging with surface-related multiples by sparse inversion

    NASA Astrophysics Data System (ADS)

    Tu, Ning; Herrmann, Felix J.

    2015-04-01

    In marine exploration seismology, surface-related multiples are usually treated as noise mainly because subsequent processing steps, such as migration velocity analysis and imaging, require multiple-free data. Failure to remove these wavefield components from the data may lead to erroneous estimates for migration velocity or result in strong coherent artefacts that interfere with the imaged reflectors. However, multiples can carry complementary information compared to primaries, as they interact with the free surface and are therefore exposed more to the subsurface. Recent work has shown that when processed correctly multiples can improve seismic illumination. Given a sufficiently accurate background velocity model and an estimate for the source signature, we propose a new and computationally efficient linearized inversion procedure based on two-way wave equations, which produces accurate images of the subsurface from the total upgoing wavefield including surface-related multiples. Modelling of the surface-related multiples in the proposed method derives from the well-known surface-related multiple elimination method. We incur a minimal overhead from incorporating the multiples by having the wave-equation solver carry out the multiple predictions via the inclusion of an areal source instead of expensive dense matrix-matrix multiplications. By using subsampling techniques, we obtain high-quality true-amplitude least-squares migrated images at computational costs of roughly a single reverse-time migration (RTM) with all the data. These images are virtually free of coherent artefacts from multiples. Proper inversion of the multiples would be computationally infeasible without using these techniques that significantly bring down the cost. By promoting sparsity in the curvelet domain and using rerandomization, out method gains improved robustness to errors in the background velocity model, and errors incurred in the linearization of the wave equation with respect to the

  19. A Simple and Fast Spline Filtering Algorithm for Surface Metrology.

    PubMed

    Zhang, Hao; Ott, Daniel; Song, John; Tong, Mingsi; Chu, Wei

    2015-01-01

    Spline filters and their corresponding robust filters are commonly used filters recommended in ISO (the International Organization for Standardization) standards for surface evaluation. Generally, these linear and non-linear spline filters, composed of symmetric, positive-definite matrices, are solved in an iterative fashion based on a Cholesky decomposition. They have been demonstrated to be relatively efficient, but complicated and inconvenient to implement. A new spline-filter algorithm is proposed by means of the discrete cosine transform or the discrete Fourier transform. The algorithm is conceptually simple and very convenient to implement.

  20. Fast globally optimal single surface segmentation using regional properties

    NASA Astrophysics Data System (ADS)

    Dou, Xin; Wu, Xiaodong

    2010-03-01

    Efficient segmentation of globally optimal surfaces in volumetric images is a central problem in many medical image analysis applications. Intra-class variance has been successfully utilized, for instance, in the Chan-Vese model especially for images without prominent edges. In this paper, we study the optimization problem of detecting a region (volume) bounded by a smooth terrain-like surface, whose intra-class variance is minimized. A novel polynomial time algorithm is developed. Our algorithm is based on the shape probing technique in computational geometry and computes a sequence of O(n) maximum flows in the derived graphs, where n is the size of the input image. Our further investigation shows that those O(n) graphs form a monotone parametric flow network, which enables to solving the optimal region detection problem in the complexity of computing a single maximum flow. The method has been validated on computer-synthetic volumetric images. Its applicability to clinical data sets was demonstrated on 20 3-D airway wall CT images from 6 subjects. The achieved results were highly accurate. The mean unsigned surface positioning error of outer walls of the tubes is 0.258 +/- 0.297mm, given a voxel size of 0.39 x 0.39 x 0.6mm3.

  1. A New Fast Algorithm to Completely Account for Non-Lambertian Surface Reflection of The Earth

    NASA Technical Reports Server (NTRS)

    Qin, Wen-Han; Herman, Jay R.; Ahmad, Ziauddin; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Surface bidirectional reflectance distribution function (BRDF) influences not only radiance just about the surface, but that emerging from the top of the atmosphere (TOA). In this study we propose a new, fast and accurate, algorithm CASBIR (correction for anisotropic surface bidirectional reflection) to account for such influences on radiance measured above TOA. This new algorithm is based on a 4-stream theory that separates the radiation field into direct and diffuse components in both upwelling and downwelling directions. This is important because the direct component accounts for a substantial portion of incident radiation under a clear sky, and the BRDF effect is strongest in the reflection of the direct radiation reaching the surface. The model is validated by comparison with a full-scale, vector radiation transfer model for the atmosphere-surface system. The result demonstrates that CASBIR performs very well (with overall relative difference of less than one percent) for all solar and viewing zenith and azimuth angles considered in wavelengths from ultraviolet to near-infrared over three typical, but very different surface types. Application of this algorithm includes both accounting for non-Lambertian surface scattering on the emergent radiation above TOA and a potential approach for surface BRDF retrieval from satellite measured radiance.

  2. Method for combining fast surface and exact volume visualization techniques in medicine

    NASA Astrophysics Data System (ADS)

    Englmeier, Karl-Hans; Haubner, Michael; Foerterer, H. M.; Perzl, W.; Fink, B. K.; Fink, U.

    1994-05-01

    In order to enable the interaction with and manipulation of 3-D data sets in the realm of medical diagnosis and therapy planning we developed a modified Z-merging algorithm that includes transparency and texture mapping features. For this an extended shape based interpolation model creates isotropic grayscale data volume in case of spatial image sequences. Interesting anatomical regions such as soft tissue, organs, and bones are detected by automatic and interactive segmentation procedures. Following that, a fully automatic surface construction algorithm detects the 3-D object boundaries by fitting geometric primitives to the binary data. The surface representations support the user with a fast overview about the structure of the 3D scene. Texture mapping is implemented as the projection of the gray values of the isotropic voxels onto a polygonal surface. Adaptive refinement, Phong's normal interpolation, and transparency are the most important features of this raytracer. The described technique enables the simultaneous display of multimodal 3D image data.

  3. Stroboscopic Surface Thermal Lensing for Fast Detection of Thermal Defects in Large-Scaled Coating Films.

    PubMed

    Tao, Chunxian; Zhang, Dawei; Hong, Ruijin; Wang, Zhongfei

    2015-01-01

    A stroboscopic surface thermal lensing (SSTL) system for the fast detection of thermal-induced defects in large-scaled optical coating films was constructed. The SSTL signal was generated by a set of double-modulators and captured by a high speed matrix camera, respectively. The spot size of both pump laser and probe laser expanded for larger detection area was finished in a single step. Based on the STL technique, both the mapping of amplitude and the phase of SSTL signal on the whole area of the coatings can be achieved simultaneously.

  4. Reactive scattering of H{sub 2} from metal surfaces under fast-grazing-incidence conditions

    SciTech Connect

    Diaz, C.; Martin, F.

    2010-07-15

    We have studied the interaction of molecular hydrogen with metal surfaces under fast-grazing-incidence conditions, by means of classical dynamics calculations based on density functional theory six-dimensional potential energy surfaces. We have performed calculations on two activated systems, H{sub 2}/NiAl(110) and H{sub 2}/Cu(111), and on two nonactivated systems, H{sub 2}/Pd(111) and H{sub 2}/Pd(110). We show that for rather open surfaces the computed 1-R probabilities (where R represents the reflectivity) as a function of the normal collision energy at grazing incidence (along low-Miller-index directions) mimic reasonably well the dissociative adsorption probabilities obtained at normal incidence and thermal energies from the dissociation threshold up to the saturation limit. Our results indicate that fast grazing incidence experiments could be used as complement to traditional sticking experiments at thermal energies to determine dissociative adsorption saturation limits, which are usually unreachable due to limitations in traditional molecular beam experiments

  5. Extremely Fast Numerical Integration of Ocean Surface Wave Dynamics

    DTIC Science & Technology

    2007-09-30

    1) is a natural two-space-dimension extension of the KdV equation . The periodic KP solutions include directional spreading in the wave field: y η...of the nonlinear preprocessor in the new approach for obtaining numerical solutions to nonlinear wave equations . I will now do so, but without many...analytical study and extremely fast numerical integration of the extended nonlinear Schroedinger equation for fully three dimensional wave motion

  6. A Fast Variational Method for the Construction of Resolution Adaptive C-Smooth Molecular Surfaces.

    PubMed

    Bajaj, Chandrajit L; Xu, Guoliang; Zhang, Qin

    2009-05-01

    We present a variational approach to smooth molecular (proteins, nucleic acids) surface constructions, starting from atomic coordinates, as available from the protein and nucleic-acid data banks. Molecular dynamics (MD) simulations traditionally used in understanding protein and nucleic-acid folding processes, are based on molecular force fields, and require smooth models of these molecular surfaces. To accelerate MD simulations, a popular methodology is to employ coarse grained molecular models, which represent clusters of atoms with similar physical properties by psuedo- atoms, resulting in coarser resolution molecular surfaces. We consider generation of these mixed-resolution or adaptive molecular surfaces. Our approach starts from deriving a general form second order geometric partial differential equation in the level-set formulation, by minimizing a first order energy functional which additionally includes a regularization term to minimize the occurrence of chemically infeasible molecular surface pockets or tunnel-like artifacts. To achieve even higher computational efficiency, a fast cubic B-spline C(2) interpolation algorithm is also utilized. A narrow band, tri-cubic B-spline level-set method is then used to provide C(2) smooth and resolution adaptive molecular surfaces.

  7. Using dynamic interferometric synthetic aperature radar (InSAR) to image fast-moving surface waves

    DOEpatents

    Vincent, Paul

    2005-06-28

    A new differential technique and system for imaging dynamic (fast moving) surface waves using Dynamic Interferometric Synthetic Aperture Radar (InSAR) is introduced. This differential technique and system can sample the fast-moving surface displacement waves from a plurality of moving platform positions in either a repeat-pass single-antenna or a single-pass mode having a single-antenna dual-phase receiver or having dual physically separate antennas, and reconstruct a plurality of phase differentials from a plurality of platform positions to produce a series of desired interferometric images of the fast moving waves.

  8. Fast spatial ancestry via flexible allele frequency surfaces

    PubMed Central

    Rañola, John Michael; Novembre, John; Lange, Kenneth

    2014-01-01

    Motivation: Unique modeling and computational challenges arise in locating the geographic origin of individuals based on their genetic backgrounds. Single-nucleotide polymorphisms (SNPs) vary widely in informativeness, allele frequencies change non-linearly with geography and reliable localization requires evidence to be integrated across a multitude of SNPs. These problems become even more acute for individuals of mixed ancestry. It is hardly surprising that matching genetic models to computational constraints has limited the development of methods for estimating geographic origins. We attack these related problems by borrowing ideas from image processing and optimization theory. Our proposed model divides the region of interest into pixels and operates SNP by SNP. We estimate allele frequencies across the landscape by maximizing a product of binomial likelihoods penalized by nearest neighbor interactions. Penalization smooths allele frequency estimates and promotes estimation at pixels with no data. Maximization is accomplished by a minorize–maximize (MM) algorithm. Once allele frequency surfaces are available, one can apply Bayes’ rule to compute the posterior probability that each pixel is the pixel of origin of a given person. Placement of admixed individuals on the landscape is more complicated and requires estimation of the fractional contribution of each pixel to a person’s genome. This estimation problem also succumbs to a penalized MM algorithm. Results: We applied the model to the Population Reference Sample (POPRES) data. The model gives better localization for both unmixed and admixed individuals than existing methods despite using just a small fraction of the available SNPs. Computing times are comparable with the best competing software. Availability and implementation: Software will be freely available as the OriGen package in R. Contact: ranolaj@uw.edu or klange@ucla.edu Supplementary information: Supplementary data are available at

  9. Spiraling Edge: Fast Surface Reconstruction from Partially Organized Sample Points

    SciTech Connect

    Angel, Edward; Crossno, Patricia

    1999-07-12

    Many applications produce three-dimensional points that must be further processed to generate a surface. Surface reconstruction algorithms that start with a set of unorganized points are extremely time-consuming. Sometimes, however, points are generated such that there is additional information available to the reconstruction algorithm. We present Spiraling Edge, a specialized algorithm for surface reconstruction that is three orders of magnitude faster than algorithms for the general case. In addition to sample point locations, our algorithm starts with normal information and knowledge of each point's neighbors. Our algorithm produces a localized approximation to the surface by creating a star-shaped triangulation between a point and a subset of its nearest neighbors. This surface patch is extended by locally triangulating each of the points along the edge of the patch. As each edge point is triangulated, it is removed from the edge and new edge points along the patch's edge are inserted in its place. The updated edge spirals out over the surface until the edge encounters a surface boundary and stops growing in that direction, or until the edge reduces to a small hole that is filled by the final triangle.

  10. Spiraling Edge: Fast Surface Reconstruction from Partially Organized Sample Points

    SciTech Connect

    Angel, E.; Crossno, P.

    1999-01-06

    Many applications produce three-dimensional points that must be further processed to generate a surface. Surface reconstruction algorithms that start with a set of unorganized points are extremely time-consuming. Often, however, points are generated such that there is additional information available to the reconstruction algorithm. We present a specialized algorithm for surface reconstruction that is three orders of magnitude faster than algorithms for the general case. In addition to sample point locations, our algorithm starts with normal information and knowledge of each point's neighbors. Our algorithm produces a localized approximation to the surface by creating a star-shaped triangulation between a point and a subset of its nearest neighbors. This surface patch is extended by locally triangulating each of the points along the edge of the patch. As each edge point is triangulated, it is removed from the edge and new edge points along the patch's edge are inserted in its place. The updated edge spirals out over the surface until the edge encounters a surface boundary and stops growing in that direction, or until the edge reduces to a small hole that fills itself in.

  11. Interaction of fast charges with a rough metal surface

    NASA Astrophysics Data System (ADS)

    Lyon, Keenan; Zhang, Ying-Ying; Mišković, Z. L.; Song, Yuan-Hong; Wang, You-Nian

    2015-09-01

    We use the Green function formulation of a dielectric response formalism to study the dynamic polarization of a rough metal surface by a single charged particle and by a pair of charged particles that move parallel to the surface. While the surface roughness is treated nonperturbatively, the plasmon excitation of the metal electron gas is described locally. We find that the magnitudes of both the image potential and the stopping power of a single particle are increased by the increasing roughness and decreasing correlation length of the surface. On the other hand, both the long-range wake potential of a single charged particle and the interaction potential between two particles are weakly affected by the surface roughness. However, the strongest effects of the surface roughness are seen in the correlated stopping power of two charged particles, giving rise to oscillations in the dependence of the stopping ratio on their distance, both when the interparticle axis is perpendicular to their direction of motion and when the wake-related oscillations are damped by adiabatic suppression of plasmon excitations at low particle speeds.

  12. Scintillator-based fast ion loss measurements in the EAST

    NASA Astrophysics Data System (ADS)

    Chang, J. F.; Isobe, M.; Ogawa, K.; Huang, J.; Wu, C. R.; Xu, Z.; Jin, Z.; Lin, S. Y.; Hu, L. Q.

    2016-11-01

    A new scintillator-based fast ion loss detector (FILD) has been installed on Experimental Advanced Superconducting Tokamak (EAST) to investigate the fast ion loss behavior in high performance plasma with neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH). A two dimensional 40 mm × 40 mm scintillator-coated (ZnS:Ag) stainless plate is mounted in the front of the detector, capturing the escaping fast ions. Photons from the scintillator plate are imaged with a Phantom V2010 CCD camera. The lost fast ions can be measured with the pitch angle from 60° to 120° and the gyroradius from 10 mm to 180 mm. This paper will describe the details of FILD diagnostic on EAST and describe preliminary measurements during NBI and ICRH heating.

  13. A Fast and Reliable Method for Surface Wave Tomography

    NASA Astrophysics Data System (ADS)

    Barmin, M. P.; Ritzwoller, M. H.; Levshin, A. L.

    - We describe a method to invert regional or global scale surface-wave group or phase-velocity measurements to estimate 2-D models of the distribution and strength of isotropic and azimuthally anisotropic velocity variations. Such maps have at least two purposes in monitoring the nuclear Comprehensive Test-Ban Treaty (CTBT): (1) They can be used as data to estimate the shear velocity of the crust and uppermost mantle and topography on internal interfaces which are important in event location, and (2) they can be used to estimate surface-wave travel-time correction surfaces to be used in phase-matched filters designed to extract low signal-to-noise surface-wave packets.The purpose of this paper is to describe one useful path through the large number of options available in an inversion of surface-wave data. Our method appears to provide robust and reliable dispersion maps on both global and regional scales. The technique we describe has a number of features that have motivated its development and commend its use: (1) It is developed in a spherical geometry; (2) the region of inference is defined by an arbitrary simple closed curve so that the method works equally well on local, regional, or global scales; (3) spatial smoothness and model amplitude constraints can be applied simultaneously; (4) the selection of model regularization and the smoothing parameters is highly flexible which allows for the assessment of the effect of variations in these parameters; (5) the method allows for the simultaneous estimation of spatial resolution and amplitude bias of the images; and (6) the method optionally allows for the estimation of azimuthal anisotropy.We present examples of the application of this technique to observed surface-wave group and phase velocities globally and regionally across Eurasia and Antarctica.

  14. Fast and accurate line scanner based on white light interferometry

    NASA Astrophysics Data System (ADS)

    Lambelet, Patrick; Moosburger, Rudolf

    2013-04-01

    White-light interferometry is a highly accurate technology for 3D measurements. The principle is widely utilized in surface metrology instruments but rarely adopted for in-line inspection systems. The main challenges for rolling out inspection systems based on white-light interferometry to the production floor are its sensitivity to environmental vibrations and relatively long measurement times: a large quantity of data needs to be acquired and processed in order to obtain a single topographic measurement. Heliotis developed a smart-pixel CMOS camera (lock-in camera) which is specially suited for white-light interferometry. The demodulation of the interference signal is treated at the level of the pixel which typically reduces the acquisition data by one orders of magnitude. Along with the high bandwidth of the dedicated lock-in camera, vertical scan-speeds of more than 40mm/s are reachable. The high scan speed allows for the realization of inspection systems that are rugged against external vibrations as present on the production floor. For many industrial applications such as the inspection of wafer-bumps, surface of mechanical parts and solar-panel, large areas need to be measured. In this case either the instrument or the sample are displaced laterally and several measurements are stitched together. The cycle time of such a system is mostly limited by the stepping time for multiple lateral displacements. A line-scanner based on white light interferometry would eliminate most of the stepping time while maintaining robustness and accuracy. A. Olszak proposed a simple geometry to realize such a lateral scanning interferometer. We demonstrate that such inclined interferometers can benefit significantly from the fast in-pixel demodulation capabilities of the lock-in camera. One drawback of an inclined observation perspective is that its application is limited to objects with scattering surfaces. We therefore propose an alternate geometry where the incident light is

  15. Design and verification of the miniature optical system for small object surface profile fast scanning

    NASA Astrophysics Data System (ADS)

    Chi, Sheng; Lee, Shu-Sheng; Huang, Jen, Jen-Yu; Lai, Ti-Yu; Jan, Chia-Ming; Hu, Po-Chi

    2016-04-01

    As the progress of optical technologies, different commercial 3D surface contour scanners are on the market nowadays. Most of them are used for reconstructing the surface profile of mold or mechanical objects which are larger than 50 mm×50 mm× 50 mm, and the scanning system size is about 300 mm×300 mm×100 mm. There are seldom optical systems commercialized for surface profile fast scanning for small object size less than 10 mm×10 mm×10 mm. Therefore, a miniature optical system has been designed and developed in this research work for this purpose. Since the most used scanning method of such system is line scan technology, we have developed pseudo-phase shifting digital projection technology by adopting projecting fringes and phase reconstruction method. A projector was used to project a digital fringe patterns on the object, and the fringes intensity images of the reference plane and of the sample object were recorded by a CMOS camera. The phase difference between the plane and object can be calculated from the fringes images, and the surface profile of the object was reconstructed by using the phase differences. The traditional phase shifting method was accomplished by using PZT actuator or precisely controlled motor to adjust the light source or grating and this is one of the limitations for high speed scanning. Compared with the traditional optical setup, we utilized a micro projector to project the digital fringe patterns on the sample. This diminished the phase shifting processing time and the controlled phase differences between the shifted phases become more precise. Besides, the optical path design based on a portable device scanning system was used to minimize the size and reduce the number of the system components. A screwdriver section about 7mm×5mm×5mm has been scanned and its surface profile was successfully restored. The experimental results showed that the measurement area of our system can be smaller than 10mm×10mm, the precision reached to

  16. Fast dual graph-based hotspot detection

    NASA Astrophysics Data System (ADS)

    Kahng, Andrew B.; Park, Chul-Hong; Xu, Xu

    2006-10-01

    As advanced technologies in wafer manufacturing push patterning processes toward lower-k I subwavelength printing, lithography for mass production potentially suffers from decreased patterning fidelity. This results in generation of many hotspots, which are actual device patterns with relatively large CD and image errors with respect to on-wafer targets. Hotspots can be formed under a variety of conditions such as the original design being unfriendly to the RET that is applied, unanticipated pattern combinations in rule-based OPC, or inaccuracies in model-based OPC. When these hotspots fall on locations that are critical to the electrical performance of a device, device performance and parametric yield can be significantly degraded. Previous rule-based hotspot detection methods suffer from long runtimes for complicated patterns. Also, the model generation process that captures process variation within simulation-based approaches brings significant overheads in terms of validation, measurement and parameter calibration. In this paper, we first describe a novel detection algorithm for hotspots induced by lithographic uncertainty. Our goal is to rapidly detect all lithographic hotspots without significant accuracy degradation. In other words, we propose a filtering method: as long as there are no "false negatives", i.e., we successfully have a superset of actual hotspots, then our method can dramatically reduce the layout area for golden hotspot analysis. The first step of our hotspot detection algorithm is to build a layout graph which reflects pattern-related CD variation. Given a layout L, the layout graph G = (V, E c union E p) consists of nodes V, corner edges E c and proximity edges E p. A face in the layout graph includes several close features and the edges between them. Edge weight can be calculated from a traditional 2-D model or a lookup table. We then apply a three-level hotspot detection: (1) edge-level detection finds the hotspot caused by two close

  17. GPU-based fast gamma index calculation

    NASA Astrophysics Data System (ADS)

    Gu, Xuejun; Jia, Xun; Jiang, Steve B.

    2011-03-01

    The γ-index dose comparison tool has been widely used to compare dose distributions in cancer radiotherapy. The accurate calculation of γ-index requires an exhaustive search of the closest Euclidean distance in the high-resolution dose-distance space. This is a computational intensive task when dealing with 3D dose distributions. In this work, we combine a geometric method (Ju et al 2008 Med. Phys. 35 879-87) with a radial pre-sorting technique (Wendling et al 2007 Med. Phys. 34 1647-54) and implement them on computer graphics processing units (GPUs). The developed GPU-based γ-index computational tool is evaluated on eight pairs of IMRT dose distributions. The γ-index calculations can be finished within a few seconds for all 3D testing cases on one single NVIDIA Tesla C1060 card, achieving 45-75× speedup compared to CPU computations conducted on an Intel Xeon 2.27 GHz processor. We further investigated the effect of various factors on both CPU and GPU computation time. The strategy of pre-sorting voxels based on their dose difference values speeds up the GPU calculation by about 2.7-5.5 times. For n-dimensional dose distributions, γ-index calculation time on CPU is proportional to the summation of γn over all voxels, while that on GPU is affected by γn distributions and is approximately proportional to the γn summation over all voxels. We found that increasing the resolution of dose distributions leads to a quadratic increase of computation time on CPU, while less-than-quadratic increase on GPU. The values of dose difference and distance-to-agreement criteria also have an impact on γ-index calculation time.

  18. Surface thermohardening by the fast-moving electric arch

    NASA Astrophysics Data System (ADS)

    Gabdrakhmanov, Az T.; Shafigullin, L. N.; Galimov, E. R.; Ibragimov, A. R.

    2017-01-01

    This paper describes the technology of modern engineering-plasma hardening steels and prospects of its application. It gives the opportunity to manage the process without using of cooling media, vacuum, special coatings to improve the absorptive capacity of hardened surfaces; the simplicity, the low cost, the maneuverability, a small size of the process equipment; a possibility of the automation and the robotization of technological process.

  19. He-LiF surface interaction potential from fast atom diffraction

    SciTech Connect

    Schueller, A.; Winter, H.; Gravielle, M. S.; Miraglia, J. E.; Pruneda, J. M.

    2009-12-15

    Diffraction patterns produced by grazing scattering of fast atoms from insulator surfaces are used to examine the atom-surface interaction. The method is applied to He atoms colliding with a LiF(001) surface along axial crystallographic channels. The projectile-surface potential is obtained from an accurate density-functional theory calculation, which includes polarization effects and surface relaxation. For the description of the collision process we employ the surface eikonal approximation, which takes into account quantum interference between different projectile paths. The dependence of projectile spectra on the parallel and perpendicular incident energies is experimentally and theoretically analyzed, demonstrating the range of applicability of the proposed model.

  20. Fast and Accurate Accessible Surface Area Prediction Without a Sequence Profile.

    PubMed

    Faraggi, Eshel; Kouza, Maksim; Zhou, Yaoqi; Kloczkowski, Andrzej

    2017-01-01

    A fast accessible surface area (ASA) predictor is presented. In this new approach no residue mutation profiles generated by multiple sequence alignments are used as inputs. Instead, we use only single sequence information and global features such as single-residue and two-residue compositions of the chain. The resulting predictor is both highly more efficient than sequence alignment based predictors and of comparable accuracy to them. Introduction of the global inputs significantly helps achieve this comparable accuracy. The predictor, termed ASAquick, is found to perform similarly well for so-called easy and hard cases indicating generalizability and possible usability for de-novo protein structure prediction. The source code and a Linux executables for ASAquick are available from Research and Information Systems at http://mamiris.com and from the Battelle Center for Mathematical Medicine at http://mathmed.org .

  1. Fast Electromechanical Switches Based on Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama; Wong, Eric; Epp, Larry

    2008-01-01

    Electrostatically actuated nanoelectromechanical switches based on carbon nanotubes have been fabricated and tested in a continuing effort to develop high-speed switches for a variety of stationary and portable electronic equipment. As explained below, these devices offer advantages over electrostatically actuated microelectromechanical switches, which, heretofore, have represented the state of the art of rapid, highly miniaturized electromechanical switches. Potential applications for these devices include computer memories, cellular telephones, communication networks, scientific instrumentation, and general radiation-hard electronic equipment. A representative device of the present type includes a single-wall carbon nanotube suspended over a trench about 130 nm wide and 20 nm deep in an electrically insulating material. The ends of the carbon nanotube are connected to metal electrodes, denoted the source and drain electrodes. At bottom of the trench is another metal electrode, denoted the pull electrode (see figure). In the off or open switch state, no voltage is applied, and the nanotube remains out of contact with the pull electrode. When a sufficiently large electric potential (switching potential) is applied between the pull electrode and either or both of the source and drain electrodes, the resulting electrostatic attraction bends and stretches the nanotube into contact with the pull electrode, thereby putting the switch into the "on" or "closed" state, in which substantial current (typically as much as hundreds of nanoamperes) is conducted. Devices of this type for use in initial experiments were fabricated on a thermally oxidized Si wafer, onto which Nb was sputter-deposited for use as the pull-electrode layer. Nb was chosen because its refractory nature would enable it to withstand the chemical and thermal conditions to be subsequently imposed for growing carbon nanotubes. A 200- nm-thick layer of SiO2 was formed on top of the Nb layer by plasma

  2. Basic concepts underlying fast-neutron-based contraband interrogation technology

    SciTech Connect

    Fink, C.L.; Guenther, P.T.; Smith, D.L.

    1992-01-01

    All accelerator-based fast-neutron contraband interrogation systems have many closely interrelated subsystems, whose performance parameters will be critically interdependent. For optimal overall performance, a systems analysis design approach is required. This paper provides a general overview of the interrelationships and the tradeoffs to be considered for optimization of nonaccelerator subsystems.

  3. Fast and reversible trapping of surface glycine receptors by gephyrin.

    PubMed

    Meier, J; Vannier, C; Sergé, A; Triller, A; Choquet, D

    2001-03-01

    Variations in receptor number at a given synapse are known to contribute to synaptic plasticity, but methods used to establish this idea usually do not allow for the determination of the dynamics of these phenomena. We used single-particle tracking to follow in real time, on the cell surface, movements of the glycine receptor (GlyR) with or without the GlyR stabilizing protein gephyrin. GlyR alternated within seconds between diffusive and confined states. In the absence of gephyrin, GlyR were mostly freely diffusing. Gephyrin induced long confinement periods spatially associated with submembranous clusters of gephyrin. However, even when most receptors were stabilized, they still frequently made transitions through the diffusive state. These data show that receptor number in a cluster results from a dynamic equilibrium between the pools of stabilized and freely mobile receptors. Modification of this equilibrium could be involved in regulation of the number of receptors at synapses.

  4. Fast RBF OGr for solving PDEs on arbitrary surfaces

    NASA Astrophysics Data System (ADS)

    Piret, Cécile; Dunn, Jarrett

    2016-10-01

    The Radial Basis Functions Orthogonal Gradients method (RBF-OGr) was introduced in [1] to discretize differential operators defined on arbitrary manifolds defined only by a point cloud. We take advantage of the meshfree character of RBFs, which give us a high accuracy and the flexibility to represent complex geometries in any spatial dimension. A large limitation of the RBF-OGr method was its large computational complexity, which greatly restricted the size of the point cloud. In this paper, we apply the RBF-Finite Difference (RBF-FD) technique to the RBF-OGr method for building sparse differentiation matrices discretizing continuous differential operators such as the Laplace-Beltrami operator. This method can be applied to solving PDEs on arbitrary surfaces embedded in ℛ3. We illustrate the accuracy of our new method by solving the heat equation on the unit sphere.

  5. Fast simulation method for airframe analysis based on big data

    NASA Astrophysics Data System (ADS)

    Liu, Dongliang; Zhang, Lixin

    2016-10-01

    In this paper, we employ the big data method to structural analysis by considering the correlations between loads and loads, loads and results and results and results. By means of fundamental mathematics and physical rules, the principle, feasibility and error control of the method are discussed. We then establish the analysis process and procedures. The method is validated by two examples. The results show that the fast simulation method based on big data is fast and precise when it is applied to structural analysis.

  6. Sample-Based Surface Coloring

    PubMed Central

    Bürger, Kai; Krüger, Jens; Westermann, Rüdiger

    2011-01-01

    In this paper, we present a sample-based approach for surface coloring, which is independent of the original surface resolution and representation. To achieve this, we introduce the Orthogonal Fragment Buffer (OFB)—an extension of the Layered Depth Cube—as a high-resolution view-independent surface representation. The OFB is a data structure that stores surface samples at a nearly uniform distribution over the surface, and it is specifically designed to support efficient random read/write access to these samples. The data access operations have a complexity that is logarithmic in the depth complexity of the surface. Thus, compared to data access operations in tree data structures like octrees, data-dependent memory access patterns are greatly reduced. Due to the particular sampling strategy that is employed to generate an OFB, it also maintains sample coherence, and thus, exhibits very good spatial access locality. Therefore, OFB-based surface coloring performs significantly faster than sample-based approaches using tree structures. In addition, since in an OFB, the surface samples are internally stored in uniform 2D grids, OFB-based surface coloring can efficiently be realized on the GPU to enable interactive coloring of high-resolution surfaces. On the OFB, we introduce novel algorithms for color painting using volumetric and surface-aligned brushes, and we present new approaches for particle-based color advection along surfaces in real time. Due to the intermediate surface representation we choose, our method can be used to color polygonal surfaces as well as any other type of surface that can be sampled. PMID:20616392

  7. Fast track surface mine installation on the critical path

    SciTech Connect

    Willison, L.R.

    1986-07-01

    A deep mining area, located in the rugged woodland hills of central West Virginia, was transformed into a beehive of activity as a major new mine and preparation plant was constructed on a very tight deadline. By the time the mine was on line, BethEnergy Mines had spent $40 million to develop the two million tpy (ton per year) surface coal mining complex. In early 1984 not a stick of timber had been cut. But within a very short time (coal-wise) there was a mining area; a 600-tph heavy media cyclone preparation plant, with 36,000 and 24,000 tons of raw and clean coal storage respectively; three miles of haul roads and access roads; a 64,000-ton clean coal stocking facility with a 4000-tph reclaim system that feeds a batch-weighing, floodloading, unit-train loadout facility; a 3.5-mile railroad spur and loop; and all incidental infrastructure. This feat entailed moving more than four million cu-yd of earth, building the preparation plant and loadout facility from ground to operating in six moths, and constructing a railroad spur bridging a major highway.

  8. Advanced vapor recognition materials for selective and fast responsive surface acoustic wave sensors: a review.

    PubMed

    Afzal, Adeel; Iqbal, Naseer; Mujahid, Adnan; Schirhagl, Romana

    2013-07-17

    The necessity of selectively detecting various organic vapors is primitive not only with respect to regular environmental and industrial hazard monitoring, but also in detecting explosives to combat terrorism and for defense applications. Today, the huge arsenal of micro-sensors has revolutionized the traditional methods of analysis by, e.g. replacing expensive laboratory equipment, and has made the remote screening of atmospheric threats possible. Surface acoustic wave (SAW) sensors - based on piezoelectric crystal resonators - are extremely sensitive to even very small perturbations in the external atmosphere, because the energy associated with the acoustic waves is confined to the crystal surface. Combined with suitably designed molecular recognition materials SAW devices could develop into highly selective and fast responsive miniaturized sensors, which are capable of continuously monitoring a specific organic gas, preferably in the sub-ppm regime. For this purpose, different types of recognition layers ranging from nanostructured metal oxides and carbons to pristine or molecularly imprinted polymers and self-assembled monolayers have been applied in the past decade. We present a critical review of the recent developments in nano- and micro-engineered synthetic recognition materials predominantly used for SAW-based organic vapor sensors. Besides highlighting their potential to realize real-time vapor sensing, their limitations and future perspectives are also discussed.

  9. A novel fast full inversion based breast ultrasound elastography technique.

    PubMed

    Karimi, Hirad; Fenster, Aaron; Samani, Abbas

    2013-04-07

    Cancer detection and classification have been the focus of many imaging and therapeutic research studies. Elastography is a non-invasive technique to visualize suspicious soft tissue areas where tissue stiffness is used as image contrast mechanism. In this study, a breast ultrasound elastography system including software and hardware is proposed. Unlike current elastography systems that image the tissue strain and present it as an approximation to relative tissue stiffness, this system is capable of imaging the breast absolute Young's modulus in fast fashion. To improve the quality of elastography images, a novel system consisting of two load cells has been attached to the ultrasound probe. The load cells measure the breast surface forces to be used for calculating the tissue stress distribution throughout the breast. To facilitate fast imaging, this stress calculation is conducted by an accelerated finite element method. Acquired tissue displacements and surface force data are used as input to the proposed Young's modulus reconstruction technique. Numerical and tissue mimicking phantom studies were conducted for validating the proposed system. These studies indicated that fast imaging of breast tissue absolute Young's modulus using the proposed ultrasound elastography system is feasible. The tissue mimicking phantom study indicated that the system is capable of providing reliable absolute Young's modulus values for both normal tissue and tumour as the maximum Young's modulus reconstruction error was less than 6%. This demonstrates that the proposed system has a good potential to be used for clinical breast cancer assessment.

  10. A novel fast full inversion based breast ultrasound elastography technique

    NASA Astrophysics Data System (ADS)

    Karimi, Hirad; Fenster, Aaron; Samani, Abbas

    2013-04-01

    Cancer detection and classification have been the focus of many imaging and therapeutic research studies. Elastography is a non-invasive technique to visualize suspicious soft tissue areas where tissue stiffness is used as image contrast mechanism. In this study, a breast ultrasound elastography system including software and hardware is proposed. Unlike current elastography systems that image the tissue strain and present it as an approximation to relative tissue stiffness, this system is capable of imaging the breast absolute Young’s modulus in fast fashion. To improve the quality of elastography images, a novel system consisting of two load cells has been attached to the ultrasound probe. The load cells measure the breast surface forces to be used for calculating the tissue stress distribution throughout the breast. To facilitate fast imaging, this stress calculation is conducted by an accelerated finite element method. Acquired tissue displacements and surface force data are used as input to the proposed Young’s modulus reconstruction technique. Numerical and tissue mimicking phantom studies were conducted for validating the proposed system. These studies indicated that fast imaging of breast tissue absolute Young’s modulus using the proposed ultrasound elastography system is feasible. The tissue mimicking phantom study indicated that the system is capable of providing reliable absolute Young’s modulus values for both normal tissue and tumour as the maximum Young’s modulus reconstruction error was less than 6%. This demonstrates that the proposed system has a good potential to be used for clinical breast cancer assessment.

  11. Novel computer program for fast exact calculation of accessible and molecular surface areas and average surface curvature.

    PubMed

    Tsodikov, Oleg V; Record, M Thomas; Sergeev, Yuri V

    2002-04-30

    New computer programs, SurfRace and FastSurf, perform fast calculations of the solvent accessible and molecular (solvent excluded) surface areas of macromolecules. Program SurfRace also calculates the areas of cavities inaccessible from the outside. We introduce the definition of average curvature of molecular surface and calculate average molecular surface curvatures for each atom in a structure. All surface area and curvature calculations are analytic and therefore yield exact values of these quantities. High calculation speed of this software is achieved primarily by avoiding computationally expensive mathematical procedures wherever possible and by efficient handling of surface data structures. The programs are written initially in the language C for PCs running Windows 2000/98/NT, but their code is portable to other platforms with only minor changes in input-output procedures. The algorithm is robust and does not ignore either multiplicity or degeneracy of atomic overlaps. Fast, memory-efficient and robust execution make this software attractive for applications both in computationally expensive energy minimization algorithms, such as docking or molecular dynamics simulations, and in stand-alone surface area and curvature calculations.

  12. GEM-based detectors for thermal and fast neutrons

    NASA Astrophysics Data System (ADS)

    Croci, G.; Claps, G.; Cazzaniga, C.; Foggetta, L.; Muraro, A.; Valente, P.

    2015-06-01

    Lately the problem of 3He replacement for neutron detection stimulated an intense activity research on alternative technologies based on alternative neutron converters. This paper presents briefly the results obtained with new GEM detectors optimized for fast and thermal neutrons. For thermal neutrons, we realized a side-on GEM detector based on a series of boron-coated alumina sheets placed perpendicularly to the incident neutron beam direction. This prototype has been tested at n@BTF photo-production neutron facilty in order to test its effectiveness under a very high flux gamma background. For fast neutrons, we developed new GEM detectors (called nGEM) for the CNESM diagnostic system of the SPIDER NBI prototype for ITER (RFX-Consortium, Italy) and as beam monitor for fast neutrons lines at spallation sources. The nGEM is a Triple GEM gaseous detector equipped with a polyethylene layer used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the results obtained by testing a medium size (30 × 25 cm2 active area) nGEM detector at the ISIS spallation source on the VESUVIO beam line.

  13. Effect of fast mold surface temperature evolution on iPP part morphology gradients

    NASA Astrophysics Data System (ADS)

    Liparoti, Sara; Sorrentino, Andrea; Guzman, Gustavo; Cakmak, Mukerrem; Titomanlio, Giuseppe

    2016-03-01

    The control of mold surface temperature is an important factor that affects the sample surface morphology as well as the structural gradients (orientation crystal size, and type) as well as cooling stresses. The frozen layer thickness formed during the filling stage also has a very significant effect on the flow resistance and thus on the resulting pressure drop and flow length in thin wall parts. The possibility to have a hot mold during filling and a quick cooling soon afterward is a significant process enhancement particularly for specialized applications such as micro injection molding and for the reproduction of micro structured surfaces. Up to now, several methods (electromagnetic, infrared, hot vapor fleshing etc,) were tried to achieve fast temperature evolution of the mold. Unfortunately, all these methods require a complex balance between thermal and mechanical problems, equipment cost, energy consumption, safety, molding cycle time and part quality achievable. In this work, a thin electrical resistance was designed and used to generate a fast and confined temperature variation on mold surface (by joule effect). Since the whole temperature evolution can take place in a few seconds, one can couple the advantages of a high surface temperature during filling with the advantages of a low mold temperature, fast cooling and low heating dissipation. Some experiments were performed with a commercial iPP resin. The effects of the surface temperature and of the heating time (under constant electric power) on surface finishing and on the final morphology (thickness and structure of the different layers) are explored and discussed.

  14. Planetary Surface Analysis Using Fast Laser Spectroscopic Techniques: Combined Microscopic Raman, LIBS, and Fluorescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Blacksberg, J.; Rossman, G. R.; Maruyama, Y.; Charbon, E.

    2011-12-01

    In situ exploration of planetary surfaces has to date required multiple techniques that, when used together, yield important information about their formation histories and evolution. We present a time-resolved laser spectroscopic technique that could potentially collect complementary sets of data providing information on mineral structure, composition, and hydration state. Using a picosecond-scale pulsed laser and a fast time-resolved detector we can simultaneously collect spectra from Raman, Laser Induced Breakdown Spectroscopy (LIBS), and fluorescence emissions that are separated in time due to the unique decay times of each process. The use of a laser with high rep rate (40 KHz) and low pulse energy (1 μJ/pulse) allows us to rapidly collect high signal to noise Raman spectra while minimizing sample damage. Increasing the pulse energy by about an order of magnitude creates a microscopic plasma near the surface and enables the collection of LIBS spectra at an unusually high rep rate and low pulse energy. Simultaneously, broader fluorescence peaks can be detected with lifetimes varying from nanosecond to microsecond. We will present Raman, LIBS, and fluorescence spectra obtained on natural mineral samples such as sulfates, clays, pyroxenes and carbonates that are of interest for Mars mineralogy. We demonstrate this technique using a photocathode-based streak camera detector as well as a newly-developed solid state Single Photon Avalanche Diode (SPAD) sensor array based on Complementary Metal-Oxide Semiconductor (CMOS) technology. We will discuss the impact of system design and detector choice on science return of a potential planetary surface mission, with a specific focus on size, weight, power, and complexity. The research described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA).

  15. Fast wavelet based algorithms for linear evolution equations

    NASA Technical Reports Server (NTRS)

    Engquist, Bjorn; Osher, Stanley; Zhong, Sifen

    1992-01-01

    A class was devised of fast wavelet based algorithms for linear evolution equations whose coefficients are time independent. The method draws on the work of Beylkin, Coifman, and Rokhlin which they applied to general Calderon-Zygmund type integral operators. A modification of their idea is applied to linear hyperbolic and parabolic equations, with spatially varying coefficients. A significant speedup over standard methods is obtained when applied to hyperbolic equations in one space dimension and parabolic equations in multidimensions.

  16. Fast image matching algorithm based on projection characteristics

    NASA Astrophysics Data System (ADS)

    Zhou, Lijuan; Yue, Xiaobo; Zhou, Lijun

    2011-06-01

    Based on analyzing the traditional template matching algorithm, this paper identified the key factors restricting the speed of matching and put forward a brand new fast matching algorithm based on projection. Projecting the grayscale image, this algorithm converts the two-dimensional information of the image into one-dimensional one, and then matches and identifies through one-dimensional correlation, meanwhile, because of normalization has been done, when the image brightness or signal amplitude increasing in proportion, it could also perform correct matching. Experimental results show that the projection characteristics based image registration method proposed in this article could greatly improve the matching speed, which ensuring the matching accuracy as well.

  17. Fast conical surface evaluation via randomized algorithm in the null-screen test

    NASA Astrophysics Data System (ADS)

    Aguirre-Aguirre, D.; Díaz-Uribe, R.; Villalobos-Mendoza, B.

    2017-01-01

    This work shows a method to recover the shape of the surface via randomized algorithms when the null-screen test is used, instead of the integration process that is commonly performed. This, because the majority of the errors are added during the reconstruction of the surface (or the integration process). This kind of large surfaces are widely used in the aerospace sector and industry in general, and a big problem exists when these surfaces have to be tested. The null-screen method is a low-cost test, and a complete surface analysis can be done by using this method. In this paper, we show the simulations done for the analysis of fast conic surfaces, where it was proved that the quality and shape of a surface under study can be recovered with a percentage error < 2.

  18. Electrical studies on silver based fast ion conducting glassy materials

    SciTech Connect

    Rao, B. Appa Kumar, E. Ramesh Kumari, K. Rajani Bhikshamaiah, G.

    2014-04-24

    Among all the available fast ion conductors, silver based glasses exhibit high conductivity. Further, glasses containing silver iodide enhances fast ion conducting behavior at room temperature. Glasses of various compositions of silver based fast ion conductors in the AgI−Ag{sub 2}O−[(1−x)B{sub 2}O{sub 3}−xTeO{sub 2}] (x=0 to1 mol% in steps of 0.2) glassy system have been prepared by melt quenching method. The glassy nature of the compounds has been confirmed by X-ray diffraction. The electrical conductivity (AC) measurements have been carried out in the frequency range of 1 KHz–3MHz by Impedance Analyzer in the temperature range 303–423K. The DC conductivity measurements were also carried out in the temperature range 300–523K. From both AC and DC conductivity studies, it is found that the conductivity increases and activation energy decreases with increasing the concentration of TeO{sub 2} as well as with temperature. The conductivity of the present glass system is found to be of the order of 10{sup −2} S/cm at room temperature. The ionic transport number of these glasses is found to be 0.999 indicating that these glasses can be used as electrolyte in batteries.

  19. Vehicle Emission Inspection and Maintenance (I/M) Provision in the Fixing America’s Surface Transportation (FAST) Act

    EPA Pesticide Factsheets

    This document is a memorandum regarding Vehicle Emission Inspection and Maintenance (I/M) Provision in Fixing America's Surface Transportation (FAST) Act, which provides long-term funding certainty for surface transportation infrastructure planning

  20. Surface stress-based biosensors.

    PubMed

    Sang, Shengbo; Zhao, Yuan; Zhang, Wendong; Li, Pengwei; Hu, Jie; Li, Gang

    2014-01-15

    Surface stress-based biosensors, as one kind of label-free biosensors, have attracted lots of attention in the process of information gathering and measurement for the biological, chemical and medical application with the development of technology and society. This kind of biosensors offers many advantages such as short response time (less than milliseconds) and a typical sensitivity at nanogram, picoliter, femtojoule and attomolar level. Furthermore, it simplifies sample preparation and testing procedures. In this work, progress made towards the use of surface stress-based biosensors for achieving better performance is critically reviewed, including our recent achievement, the optimally circular membrane-based biosensors and biosensor array. The further scientific and technological challenges in this field are also summarized. Critical remark and future steps towards the ultimate surface stress-based biosensors are addressed.

  1. COMBINED ANALYSIS OF THORIUM AND FAST NEUTRON DATA AT THE LUNAR SURFACE

    SciTech Connect

    O. GASNAULT; W. FELDMAN; ET AL

    2001-01-01

    The global distribution of the radioactive elements (U, K, Th) at the lunar surface is an important parameter for an understanding of lunar evolution, because they have provided continuous heat over the lifetime of the Moon. Today, only the thorium distribution is available for the whole lunar surface [1]. Another key parameter that characterize the surface of the Moon is the presence of mare basalts. These basalts are concentrated on the nearside and are represented by materials with high-Fe content, sometimes associated with high-Ti. We demonstrated elsewhere that the fast neutron measurement made by Lunar Prospector is representative of the average soil atomic mass [2]. is primarily dominated by Fe and Ti in basaltic terranes, and therefore the map of the fast neutrons provides a good delineation of mare basalts. We focus here on the correlated variations of thorium abundances and fast neutron fluxes averaged over areas of 360 km in diameter, in an attempt to provide a better understanding of the thorium emplacement on the surface of the Moon.

  2. Correlation-coefficient-based fast template matching through partial elimination.

    PubMed

    Mahmood, Arif; Khan, Sohaib

    2012-04-01

    Partial computation elimination techniques are often used for fast template matching. At a particular search location, computations are prematurely terminated as soon as it is found that this location cannot compete with an already known best match location. Due to the nonmonotonic growth pattern of the correlation-based similarity measures, partial computation elimination techniques have been traditionally considered inapplicable to speed up these measures. In this paper, we show that partial elimination techniques may be applied to a correlation coefficient by using a monotonic formulation, and we propose basic-mode and extended-mode partial correlation elimination algorithms for fast template matching. The basic-mode algorithm is more efficient on small template sizes, whereas the extended mode is faster on medium and larger templates. We also propose a strategy to decide which algorithm to use for a given data set. To achieve a high speedup, elimination algorithms require an initial guess of the peak correlation value. We propose two initialization schemes including a coarse-to-fine scheme for larger templates and a two-stage technique for small- and medium-sized templates. Our proposed algorithms are exact, i.e., having exhaustive equivalent accuracy, and are compared with the existing fast techniques using real image data sets on a wide variety of template sizes. While the actual speedups are data dependent, in most cases, our proposed algorithms have been found to be significantly faster than the other algorithms.

  3. Formulation and optimization of fast dissolving intraoral drug delivery system for clobazam using response surface methodology

    PubMed Central

    Bala, Rajni; Khanna, Sushil; Pawar, Pravin K.

    2013-01-01

    Clobazam is a newer 1,5-benzodiazepine used for the treatment of epilepsy. It is better tolerated and less sedating than other benzodiazepines. Absorption of the drug can be impacted by oral fast dissolving dosage form; this may have implications for epilepsy in pediatrics and those having difficulty in swallowing tablets/capsules resulting in improved patient compliance. The purpose of the present investigation was to formulate and optimize clobazam oro-dissolving tablets by direct compression method using response surface methodology (RSM). Oro-dispersible tablets of clobazam were prepared by direct compression method using crospovidone (2-6%) as a superdisintegrant, microcrystalline cellulose (MCC) (20-40%) was used as diluents along with directly compressible mannitol to enhance mouth feel. A 32 full factorial design was applied to investigate the combined effect of two formulation variables: amount of crospovidone and MCC over the independent variables disintegration time, wetting time and percent drug release. Disintegration time showed by all formulations was found to be in the range of 24.3-193 s based on evaluation parameters the formulation containing 6% of crospovidone and 30% of MCC showed promising performance against all other formulations. The results demonstrated that the RSM could efficiently be applied for the formulation of clobazam oro-dispersible tablets; therefore, constitute an advance in the management of epileptic attacks. PMID:24083203

  4. Automated system for fast and accurate analysis of SF6 injected in the surface ocean.

    PubMed

    Koo, Chul-Min; Lee, Kitack; Kim, Miok; Kim, Dae-Ok

    2005-11-01

    This paper describes an automated sampling and analysis system for the shipboard measurement of dissolved sulfur hexafluoride (SF6) in surface marine environments into which SF6 has been deliberately released. This underway system includes a gas chromatograph associated with an electron capture detector, a fast and highly efficient SF6-extraction device, a global positioning system, and a data acquisition system based on Visual Basic 6.0/C 6.0. This work is distinct from previous studies in that it quantifies the efficiency of the SF6-extraction device and its carryover effect and examines the effect of surfactant on the SF6-extraction efficiency. Measurements can be continuously performed on seawater samples taken from a seawater line installed onboard a research vessel. The system runs on an hourly cycle during which one set of four SF6 standards is measured and SF6 derived from the seawater stream is subsequently analyzed for the rest of each 1 h period. This state-of-art system was successfully used to trace a water mass carrying Cochlodinium polykrikoides, which causes harmful algal blooms (HAB) in the coastal waters of southern Korea. The successful application of this analysis system in tracing the HAB-infected water mass suggests that the SF6 detection method described in this paper will improve the quality of the future study of biogeochemical processes in the marine environment.

  5. Impacts of fast meteoroids and the separation of dust particles from the surface of the Moon

    NASA Astrophysics Data System (ADS)

    Popel, S. I.; Golub', A. P.; Lisin, E. A.; Izvekova, Yu. N.; Atamaniuk, B.; Dol'nikov, G. G.; Zakharov, A. V.; Zelenyi, L. M.

    2016-05-01

    The possibility of the separation of dust particles owing to impacts of micrometeoroids on the surface of the Moon has been discussed. It has been shown that this effect is significant and should be taken into account when determining the number of particles rising over the surface of the Moon at the formation of a plasma-dust system. The average number of regolith particles leaving the surface of the Moon owing to the impacts of fast meteoroids has been determined for various altitudes over the Moon. The size distribution function of particles leaving the surface of the Moon because of impacts of meteoroids has been determined. It has been shown that impacts of meteoroids constitute an important source of dust microparticles in the plasma-dust system over the surface of the Moon.

  6. Fast Waves at the Base of the Cochlea

    PubMed Central

    Recio-Spinoso, Alberto; Rhode, William S.

    2015-01-01

    Georg von Békésy observed that the onset times of responses to brief-duration stimuli vary as a function of distance from the stapes, with basal regions starting to move earlier than apical ones. He noticed that the speed of signal propagation along the cochlea is slow when compared with the speed of sound in water. Fast traveling waves have been recorded in the cochlea, but their existence is interpreted as the result of an experiment artifact. Accounts of the timing of vibration onsets at the base of the cochlea generally agree with Békésy’s results. Some authors, however, have argued that the measured delays are too short for consistency with Békésy’s theory. To investigate the speed of the traveling wave at the base of the cochlea, we analyzed basilar membrane (BM) responses to clicks recorded at several locations in the base of the chinchilla cochlea. The initial component of the BM response matches remarkably well the initial component of the stapes response, after a 4-μs delay of the latter. A similar conclusion is reached by analyzing onset times of time-domain gain functions, which correspond to BM click responses normalized by middle-ear input. Our results suggest that BM responses to clicks arise from a combination of fast and slow traveling waves. PMID:26062000

  7. Fast Waves at the Base of the Cochlea.

    PubMed

    Recio-Spinoso, Alberto; Rhode, William S

    2015-01-01

    Georg von Békésy observed that the onset times of responses to brief-duration stimuli vary as a function of distance from the stapes, with basal regions starting to move earlier than apical ones. He noticed that the speed of signal propagation along the cochlea is slow when compared with the speed of sound in water. Fast traveling waves have been recorded in the cochlea, but their existence is interpreted as the result of an experiment artifact. Accounts of the timing of vibration onsets at the base of the cochlea generally agree with Békésy's results. Some authors, however, have argued that the measured delays are too short for consistency with Békésy's theory. To investigate the speed of the traveling wave at the base of the cochlea, we analyzed basilar membrane (BM) responses to clicks recorded at several locations in the base of the chinchilla cochlea. The initial component of the BM response matches remarkably well the initial component of the stapes response, after a 4-μs delay of the latter. A similar conclusion is reached by analyzing onset times of time-domain gain functions, which correspond to BM click responses normalized by middle-ear input. Our results suggest that BM responses to clicks arise from a combination of fast and slow traveling waves.

  8. Effect of surface modes on coupling to fast waves in the LHRF

    SciTech Connect

    Pinsker, R.I.; Colestock, P.L.

    1990-09-16

    The effect of surface modes of propagation on coupling to fast waves in the LHRF is studied theoretically and experimentally. The previously reported up-down' poloidal phasing asymmetry for coupling to a uniform plasma is shown to be due to the properties of a mode which carries energy along the plasma-conducting wall interface. Comparison of the theory with coupling experiments performed on the PLT tokamak with a phased array of twelve dielectric-loaded waveguides at 800 MHz shows that the observed dependence of the net reflection coefficient on toroidal phase angle can be explained only if the surface wave is taken into account. 43 refs., 10 figs.

  9. Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer

    PubMed Central

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.

    2014-01-01

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications. PMID:25425458

  10. Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer

    NASA Astrophysics Data System (ADS)

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.

    2014-11-01

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications.

  11. Fast response and high sensitivity ZnO/glass surface acoustic wave humidity sensors using graphene oxide sensing layer.

    PubMed

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J K

    2014-11-26

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications.

  12. Parameter tuning for the NFFT based fast Ewald summation

    NASA Astrophysics Data System (ADS)

    Nestler, Franziska

    2016-07-01

    The computation of the Coulomb potentials and forces in charged particle systems under 3d-periodic boundary conditions is possible in an efficient way by utilizing the Ewald summation formulas and applying the fast Fourier transform (FFT). In this paper we consider the particle-particle NFFT (P^2NFFT) approach, which is based on the fast Fourier transform for nonequispaced data (NFFT) and compare the error behaviors regarding different window functions, which are used in order to approximate the given continuous charge distribution by a mesh based charge density. Typically B-splines are applied in the scope of particle mesh methods, as for instance within the well known particle-particle particle-mesh (P^3M) algorithm. The publicly available P^2NFFT algorithm allows the application of an oversampled FFT as well as the usage of different window functions. We consider for the first time also an approximation by Bessel functions and show how the resulting root mean square errors in the forces can be predicted precisely and efficiently. The results show that, if the parameters are tuned appropriately, the Bessel window function is in many cases even the better choice in terms of computational costs. Moreover, the results indicate that it is often advantageous in terms of efficiency to spend some oversampling within the NFFT while using a window function with a smaller support.

  13. Scatterometry—fast and robust measurements of nano-textured surfaces

    NASA Astrophysics Data System (ADS)

    Hannibal Madsen, Morten; Hansen, Poul-Erik

    2016-06-01

    Scatterometry is a fast, precise and low cost way to determine the mean pitch and dimensional parameters of periodic structures with lateral resolution of a few nanometer. It is robust enough for in-line process control and precise and accurate enough for metrology measurements. Furthermore, scatterometry is a non-destructive technique capable of measuring buried structures, for example a grating covered by a thick oxide layer. As scatterometry is a non-imaging technique, mathematical modeling is needed to retrieve structural parameters that describe a surface. In this review, the three main steps of scatterometry are discussed: the data acquisition, the simulation of diffraction efficiencies and the comparison of data and simulations. First, the intensity of the diffracted light is measured with a scatterometer as a function of incoming angle, diffraction angle and/or wavelength. We discuss the evolution of the scatterometers from the earliest angular scatterometers to the new imaging scatterometers. The basic principle of measuring diffraction efficiencies in scatterometry has remained the same since the beginning, but the instrumental improvements have made scatterometry a state-of-the-art solution for fast and accurate measurements of nano-textured surfaces. The improvements include extending the wavelength range from the visible to the extreme ultra-violet range, development of Fourier optics to measure all diffraction orders simultaneously, and an imaging scatterometer to measure area of interests smaller than the spot size. Secondly, computer simulations of the diffraction efficiencies are discussed with emphasis on the rigorous coupled-wave analysis (RCWA) method. RCWA has, since the mid-1990s, been the preferred method for grating simulations due to the speed of the algorithms. In the beginning the RCWA method suffered from a very slow convergence rate, and we discuss the historical improvements to overcome this challenge, e.g. by the introduction of Li

  14. The transport characteristics of passing fast ions produced by nonlocal overlapping of drift island surfaces and magnetic island surfaces

    NASA Astrophysics Data System (ADS)

    Cao, Jinjia; Gong, Xueyu; Xiang, Dong; Huang, Qianhong; Yu, Jun

    2016-08-01

    The structure of the drift-island surface of passing fast ions (PFIs) is investigated in the presence of the resonant interaction with a magnetic island. Two overlapping regions of the drift-island surface and the magnetic island surface are found, one corresponding to local overlapping region and the other to non-local one. Here, the word "nonlocal" denotes that the resonances in the core plasma can have effects on the PFIs near the plasma boundary, while the "local" represents that the PFIs just near the resonant location are influenced. The nonlocal overlapping constructs a transport path along which the PFIs can become losses. There are three kinds of drift-island surfaces to join in forming the transport paths. A pitch angle region, which is called pitch angle gap, is found near the plasma boundary, where the drift-island surface cannot be formed and few PFIs are lost. The pitch-angle selective features of PFI losses are obtained by analyzing the three kinds of drift-island surfaces. The coupling between the crowd drift island surfaces and the collision can induce the prompt losses of PFIs and rapidly slowing down of PFI energy. The time of the prompt losses and the slowing down rate are calculated. Qualitatively, the theoretical results are in well agreement with the experimental observations in ASDEX Upgrade [M. García-Muñoz et al., Nucl. Fusion 47, L10 (2007)].

  15. A fast quad-tree based two dimensional hierarchical clustering.

    PubMed

    Rajadurai, Priscilla; Sankaranarayanan, Swamynathan

    2012-01-01

    Recently, microarray technologies have become a robust technique in the area of genomics. An important step in the analysis of gene expression data is the identification of groups of genes disclosing analogous expression patterns. Cluster analysis partitions a given dataset into groups based on specified features. Euclidean distance is a widely used similarity measure for gene expression data that considers the amount of changes in gene expression. However, the huge number of genes and the intricacy of biological networks have highly increased the challenges of comprehending and interpreting the resulting group of data, increasing processing time. The proposed technique focuses on a QT based fast 2-dimensional hierarchical clustering algorithm to perform clustering. The construction of the closest pair data structure is an each level is an important time factor, which determines the processing time of clustering. The proposed model reduces the processing time and improves analysis of gene expression data.

  16. A fast image encryption algorithm based on chaotic map

    NASA Astrophysics Data System (ADS)

    Liu, Wenhao; Sun, Kehui; Zhu, Congxu

    2016-09-01

    Derived from Sine map and iterative chaotic map with infinite collapse (ICMIC), a new two-dimensional Sine ICMIC modulation map (2D-SIMM) is proposed based on a close-loop modulation coupling (CMC) model, and its chaotic performance is analyzed by means of phase diagram, Lyapunov exponent spectrum and complexity. It shows that this map has good ergodicity, hyperchaotic behavior, large maximum Lyapunov exponent and high complexity. Based on this map, a fast image encryption algorithm is proposed. In this algorithm, the confusion and diffusion processes are combined for one stage. Chaotic shift transform (CST) is proposed to efficiently change the image pixel positions, and the row and column substitutions are applied to scramble the pixel values simultaneously. The simulation and analysis results show that this algorithm has high security, low time complexity, and the abilities of resisting statistical analysis, differential, brute-force, known-plaintext and chosen-plaintext attacks.

  17. Fast surface acoustic wave-matrix-assisted laser desorption ionization mass spectrometry of cell response from islets of Langerhans.

    PubMed

    Bllaci, Loreta; Kjellström, Sven; Eliasson, Lena; Friend, James R; Yeo, Leslie Y; Nilsson, Staffan

    2013-03-05

    A desire for higher speed and performance in molecular profiling analysis at a reduced cost is driving a trend in miniaturization and simplification of procedures. Here we report the use of a surface acoustic wave (SAW) atomizer for fast sample handling in matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) peptide and protein profiling of Islets of Langerhans, for future type 2 diabetes (T2D) studies. Here the SAW atomizer was used for ultrasound (acoustic) extraction of insulin and other peptide hormones released from freshly prepared islets, stimulated directly on a membrane. A high energy propagating SAW atomizes the membrane-bound liquid into approximately 2 μm diameter droplets, rich in cell-released molecules. Besides acting as a sample carrier, the membrane provides a purification step by entrapping cell clusters and other impurities within its fibers. A new SAW-based sample-matrix deposition method for MALDI MS was developed and characterized by a strong insulin signal, and a limit of detection (LOD) lower than 100 amol was achieved. Our results support previous work reporting the SAW atomizer as a fast and inexpensive tool for ultrasound, membrane-based sample extraction. When interfaced with MALDI MS, the SAW atomizer constitutes a valuable tool for rapid cell studies. Other biomedical applications of SAW-MALDI MS are currently being developed, aiming at fast profiling of biofluids. The membrane sampling is a simplistic and noninvasive collection method of limited volume biofluids such as the gingival fluid and the tearfilm.

  18. Response surface methodology to optimize novel fast disintegrating tablets using β cyclodextrin as diluent.

    PubMed

    Late, Sameer G; Banga, Ajay K

    2010-12-01

    The objective of this work was to apply response surface approach to investigate main and interaction effects of formulation parameters in optimizing novel fast disintegrating tablet formulation using β cyclodextrin as a diluent. The variables studied were diluent (β cyclodextrin, X (1)), superdisintegrant (Croscarmellose sodium, X (2)), and direct compression aid (Spray dried lactose, X (3)). Tablets were prepared by direct compression method on B2 rotary tablet press using flat plain-face punches and characterized for weight variation, thickness, disintegration time (Y (1)), and hardness (Y (2)). Disintegration time was strongly affected by quadratic terms of β cyclodextrin, croscarmellose sodium, and spray-dried lactose. The positive value of regression coefficient for β cyclodextrin suggested that hardness increased with increased amount of β cyclodextrin. In general, disintegration of tablets has been reported to slow down with increase in hardness. However in the present study, higher concentration of β cyclodextrin was found to improve tablet hardness without increasing the disintegration time. Thus, β cyclodextrin is proposed as a suitable diluent to achieve fast disintegrating tablets with sufficient hardness. Good correlation between the predicted values and experimental data of the optimized formulation validated prognostic ability of response surface methodology in optimizing fast disintegrating tablets using β cyclodextrin as a diluent.

  19. A PDE-Based Fast Local Level Set Method

    NASA Astrophysics Data System (ADS)

    Peng, Danping; Merriman, Barry; Osher, Stanley; Zhao, Hongkai; Kang, Myungjoo

    1999-11-01

    We develop a fast method to localize the level set method of Osher and Sethian (1988, J. Comput. Phys.79, 12) and address two important issues that are intrinsic to the level set method: (a) how to extend a quantity that is given only on the interface to a neighborhood of the interface; (b) how to reset the level set function to be a signed distance function to the interface efficiently without appreciably moving the interface. This fast local level set method reduces the computational effort by one order of magnitude, works in as much generality as the original one, and is conceptually simple and easy to implement. Our approach differs from previous related works in that we extract all the information needed from the level set function (or functions in multiphase flow) and do not need to find explicitly the location of the interface in the space domain. The complexity of our method to do tasks such as extension and distance reinitialization is O(N), where N is the number of points in space, not O(N log N) as in works by Sethian (1996, Proc. Nat. Acad. Sci. 93, 1591) and Helmsen and co-workers (1996, SPIE Microlithography IX, p. 253). This complexity estimation is also valid for quite general geometrically based front motion for our localized method.

  20. Fast Field Calibration of MIMU Based on the Powell Algorithm

    PubMed Central

    Ma, Lin; Chen, Wanwan; Li, Bin; You, Zheng; Chen, Zhigang

    2014-01-01

    The calibration of micro inertial measurement units is important in ensuring the precision of navigation systems, which are equipped with microelectromechanical system sensors that suffer from various errors. However, traditional calibration methods cannot meet the demand for fast field calibration. This paper presents a fast field calibration method based on the Powell algorithm. As the key points of this calibration, the norm of the accelerometer measurement vector is equal to the gravity magnitude, and the norm of the gyro measurement vector is equal to the rotational velocity inputs. To resolve the error parameters by judging the convergence of the nonlinear equations, the Powell algorithm is applied by establishing a mathematical error model of the novel calibration. All parameters can then be obtained in this manner. A comparison of the proposed method with the traditional calibration method through navigation tests shows the classic performance of the proposed calibration method. The proposed calibration method also saves more time compared with the traditional calibration method. PMID:25177801

  1. Fast-response humidity-sensing films based on methylene blue aggregates formed on nanoporous semiconductor films

    NASA Astrophysics Data System (ADS)

    Ishizaki, Ryota; Katoh, Ryuzi

    2016-05-01

    We prepared fast-response colorimetric humidity-sensing (vapochromic) films based on methylene blue adsorption onto nanoporous semiconductor (TiO2, Al2O3) films. Color changes caused by changes of humidity could be easily identified visually. A characteristic feature of the vapochromic films was their fast response to changes of humidity. We found that the response began to occur within 10 ms. The response was rapid because all the methylene blue molecules attached to the nanoporous semiconductor surface were directly exposed to the environment. We also deduced that the color changes were caused by structural changes of the methylene blue aggregates on the surface.

  2. Fast complex memory polynomial-based adaptive digital predistorter

    NASA Astrophysics Data System (ADS)

    Singh Sappal, Amandeep; Singh Patterh, Manjeet; Sharma, Sanjay

    2011-07-01

    Today's 3G wireless systems require both high linearity and high power amplifier (PA) efficiency. The high peak-to-average ratios of the digital modulation schemes used in 3G wireless systems require that the RF PA maintain high linearity over a large range while maintaining this high efficiency; these two requirements are often at odds with each other with many of the traditional amplifier architectures. In this article, a fast and easy-to-implement adaptive digital predistorter has been presented for Wideband Code Division Multiplexed signals using complex memory polynomial work function. The proposed algorithm has been implemented to test a Motorola LDMOSFET PA. The proposed technique also takes care of the memory effects of the PA, which have been ignored in many proposed techniques in the literature. The results show that the new complex memory polynomial-based adaptive digital predistorter has better linearisation performance than conventional predistortion techniques.

  3. [Fast Implementation Method of Protein Spots Detection Based on CUDA].

    PubMed

    Xiong, Bangshu; Ye, Yijia; Ou, Qiaofeng; Zhang, Haodong

    2016-02-01

    In order to improve the efficiency of protein spots detection, a fast detection method based on CUDA was proposed. Firstly, the parallel algorithms of the three most time-consuming parts in the protein spots detection algorithm: image preprocessing, coarse protein point detection and overlapping point segmentation were studied. Then, according to single instruction multiple threads executive model of CUDA to adopted data space strategy of separating two-dimensional (2D) images into blocks, various optimizing measures such as shared memory and 2D texture memory are adopted in this study. The results show that the operative efficiency of this method is obviously improved compared to CPU calculation. As the image size increased, this method makes more improvement in efficiency, such as for the image with the size of 2,048 x 2,048, the method of CPU needs 52,641 ms, but the GPU needs only 4,384 ms.

  4. Fast spectral color image segmentation based on filtering and clustering

    NASA Astrophysics Data System (ADS)

    Xing, Min; Li, Hongyu; Jia, Jinyuan; Parkkinen, Jussi

    2009-10-01

    This paper proposes a fast approach to spectral image segmentation. In the algorithm, two popular techniques are extended and applied to spectral color images: the mean-shift filtering and the kernel-based clustering. We claim that segmentation should be completed under illuminant F11 rather than directly using the original spectral reflectance, because such illumination can reduce data variability and expedite the following filtering. The modes obtained in the mean-shift filtering represent the local features of spectral images, and will be applied to segmentation in place of pixels. Since the modes are generally small in number, the eigendecomposition of kernel matrices, the crucial step in the kernelbased clustering, becomes much easier. The combination of these two techniques can efficiently enhance the performance of segmentation. Experiments show that the proposed segmentation method is feasible and very promising for spectral color images.

  5. Fast initialization of hole spin in a quantum dot-metal surface hybrid system

    NASA Astrophysics Data System (ADS)

    Peng, Yiwei; Yu, Zhongyuan; Liu, Yumin; Wu, Tiesheng; Zhang, Wen; Ye, Han

    2015-08-01

    In this work, we theoretically investigate the preparation of hole spin in a hybrid system consisting of a quantum dot (QD) and metal-dielectric interface. A cavity quantum electrodynamics (CQED) method is used to analyze the influence of surface plasmon polaritons (SPPs) on the emission of QD. Due to coupling between spin and interface (with a different value along different direction), a fast initialization beyond the GHz range can be achieved with high fidelity at reasonable external parameters, under both continuous wave and pulse excitation. Moreover, the distance between QD and metal is proved to be the most important element.

  6. Refractive index fiber sensor based on Brillouin fast light

    NASA Astrophysics Data System (ADS)

    Chen, Jiali; Gan, Jiulin; Zhang, Zhishen; Yang, Tong; Deng, Huaqiu; Yang, Zhongmin

    2014-01-01

    A new type of refractive index fiber sensor was invented by combining the evanescent-field scattering sensing mechanism with the Brillouin fast light scheme. Superluminal light was realized using Brillouin lasing oscillation in a fiber ring cavity. The refractive index of the solution around the microfiber within the cavity is related to the group velocity of the fast light. This fast light refractive index sensor offers an alternative for high-accuracy sensing applications.

  7. Fast and Secure Chaos-Based Cryptosystem for Images

    NASA Astrophysics Data System (ADS)

    Farajallah, Mousa; El Assad, Safwan; Deforges, Olivier

    Nonlinear dynamic cryptosystems or chaos-based cryptosystems have been attracting a large amount of research since 1990. The critical aspect of cryptography is to face the growth of communication and to achieve the design of fast and secure cryptosystems. In this paper, we introduce three versions of a chaos-based cryptosystem based on a similar structure of the Zhang and Fridrich cryptosystems. Each version is composed of two layers: a confusion layer and a diffusion layer. The confusion layer is achieved by using a modified 2-D cat map to overcome the fixed-point problem and some other weaknesses, and also to increase the dynamic key space. The 32-bit logistic map is used as a diffusion layer for the first version, which is more robust than using it in 8-bit. In the other versions, the logistic map is replaced by a modified Finite Skew Tent Map (FSTM) for three reasons: to increase the nonlinearity properties of the diffusion layer, to overcome the fixed-point problem, and to increase the dynamic key space. Finally, all versions of the proposed cryptosystem are more resistant against known attacks and faster than Zhang cryptosystems. Moreover, the dynamic key space is much larger than the one used in Zhang cryptosystems. Performance and security analysis prove that the proposed cryptosystems are suitable for securing real-time applications.

  8. Spectral Emission of fast non-Maxwellian Atoms at metallic Surfaces in low density Plasmas

    NASA Astrophysics Data System (ADS)

    Dickheuer, Sven; Marchuk, Oleksandr; Brandt, Christian; Pospieszczyk, Albrecht

    2016-09-01

    We have observed Doppler shifted components of the Balmer-lines emitted by fast non-Maxwellian atoms using different targets in a linear magnetized plasma in the PSI-2 device. In a pure hydrogen plasma the Doppler shifted components of the Balmer emission lines cannot be detected above the signal-to-noise-ratio. However, in a mixed H/Ar plasma with composition of 1:1 the Doppler red- and blue-shifted components can be clearly observed. The Balmer-lines are analyzed by optical emission spectroscopy at observations angles of 35° and 90°. For target materials we use Ag, Pd, Fe and C. An acceleration potential can be applied to the target to change the kinetic energy of the incoming ions between 40 and 200 eV enabling the observation of the Doppler shifted components. The emission mechanism is discussed in details and is probably due to excitation transfer from metastable argon atoms to the fast hydrogen atoms. The Doppler shifted signal can be used to determine the properties of the surfaces, e.g., the energy and angular distribution of reflected atoms. Also the spectral reflectance of the target surface can be obtained and tested against the reference data and measurements with light calibration sources.

  9. Efficient Video Stitching Based on Fast Structure Deformation.

    PubMed

    Li, Jing; Xu, Wei; Zhang, Jianguo; Zhang, Maojun; Wang, Zhengming; Li, Xuelong

    2015-12-01

    In computer vision, video stitching is a very challenging problem. In this paper, we proposed an efficient and effective wide-view video stitching method based on fast structure deformation that is capable of simultaneously achieving quality stitching and computational efficiency. For a group of synchronized frames, firstly, an effective double-seam selection scheme is designed to search two distinct but structurally corresponding seams in the two original images. The seam location of the previous frame is further considered to preserve the interframe consistency. Secondly, along the double seams, 1-D feature detection and matching is performed to capture the structural relationship between the two adjacent views. Thirdly, after feature matching, we propose an efficient algorithm to linearly propagate the deformation vectors to eliminate structure misalignment. At last, image intensity misalignment is corrected by rapid gradient fusion based on the successive over relaxation iteration (SORI) solver. A principled solution to the initialization of the SORI significantly reduced the number of iterations required. We have compared favorably our method with seven state-of-the-art image and video stitching algorithms as well as traditional ones. Experimental results show that our method outperforms the existing ones compared in terms of overall stitching quality and computational efficiency.

  10. A pipette-based calibration system for fast-scan cyclic voltammetry with fast response times.

    PubMed

    Ramsson, Eric S

    2016-01-01

    Fast-scan cyclic voltammetry (FSCV) is an electrochemical technique that utilizes the oxidation and/or reduction of an analyte of interest to infer rapid changes in concentrations. In order to calibrate the resulting oxidative or reductive current, known concentrations of an analyte must be introduced under controlled settings. Here, I describe a simple and cost-effective method, using a Petri dish and pipettes, for the calibration of carbon fiber microelectrodes (CFMs) using FSCV.

  11. A fast, magnetics-free flux surface estimation and q-profile reconstruction algorithm for feedback control of plasma profiles

    NASA Astrophysics Data System (ADS)

    Hommen, G.; de Baar, M.; Citrin, J.; de Blank, H. J.; Voorhoeve, R. J.; de Bock, M. F. M.; Steinbuch, M.; contributors, JET-EFDA

    2013-02-01

    The flux surfaces' layout and the magnetic winding number q are important quantities for the performance and stability of tokamak plasmas. Normally, these quantities are iteratively derived by solving the plasma equilibrium for the poloidal and toroidal flux. In this work, a fast, non-iterative and magnetics-free numerical method is proposed to estimate the shape of the flux surfaces by an inward propagation of the plasma boundary shape, as can be determined for example by optical boundary reconstruction described in Hommen (2010 Rev. Sci. Instrum. 81 113504), toward the magnetic axis, as can be determined independently with the motional Stark effect (MSE) diagnostic. Flux surfaces are estimated for various plasma regimes in the ITER, JET and MAST tokamaks and are compared with results of CRONOS reconstructions and simulations, showing agreement to within 1% of the minor radius for almost all treated plasmas. The availability of the flux surface shapes combined with the pitch angles measured using MSE allow the reconstruction of the plasma q-profile, by evaluating the contour-integral over the flux surfaces of the magnetic field pitch angle. This method provides a direct and exact measure of the q-profile for arbitrary flux surface shapes, which does not rely on magnetic measurements. Results based on estimated flux surface shapes show agreement with CRONOS q-profiles of better than 10%. The impact of the shape of the flux surfaces on the q-profile, particularly the profiles of elongation and Shafranov shift, and offsets in plasma boundary and the magnetic axis are assessed. OFIT+ was conceived for real-time plasma profile control experiments and advanced tokamak operation, and provides quickly and reliably the mapping of actuators and sensors to the minor radius as well as the plasma q-profile, independent of magnetic measurements.

  12. Integrated Ray Tracing (IRT) simulation of SCOTS measurement of GMT fast steering mirror surface

    NASA Astrophysics Data System (ADS)

    Choi, Ji Nyeong; Ryu, Dongok; Kim, Sug-Whan; Graves, Logan; Su, Peng; Huang, Run; Kim, Dae Wook

    2015-09-01

    The Software Configurable Optical Testing System (SCOTS) is one of the newest testing methods for large mirror surfaces. The Integrated Ray Tracing (IRT) technique can be applicable to the SCOTS simulation by performing non-sequential ray tracing from the screen to the camera detector in the real scale. Therefore, the radiometry of distorted pattern images are numerically estimated by the IRT simulation module. In this study, we construct an IRT SCOTS simulation model for the Fast Steering Mirror Prototype (FSMP) surface of the Giant Magellan Telescope (GMT). GMT FSMP is an off-axis ellipsoidal concave mirror that is 1064 mm in diameter and has PV 3.1 mm in aspheric departure. The surface error requirement is less than 20 nm rms. The screen is modeled as an array of 1366 by 768 screen pixels of 0.227 mm in pitch size. The screen is considered as a Lambertian scattering surface. The screen and the camera are positioned around 4390 mm away from the mirror and separated by around 132 mm from each other. The light source are scanning lines and sinusoidal patterns generated by 616,050 rays per one screen pixel. Of the initially generated rays, 0.22 % are received by the camera's detector and contribute to form distorted pattern images. These images are converted to the slope and height maps of the mirror surface. The final result for the height difference between input surface and reconstructed surface was 14.14 nm rms. Additionally, the simulated mirror pattern image was compared with the real SCOTS test for the GMT FSMP. This study shows applicability of using the IRT model to SCOTS simulation with nanometer level numerical accuracy.

  13. Coupled slow and fast surface dynamics in an electrocatalytic oscillator: Model and simulations

    SciTech Connect

    Nascimento, Melke A.; Nagao, Raphael; Eiswirth, Markus; Varela, Hamilton

    2014-12-21

    The co-existence of disparate time scales is pervasive in many systems. In particular for surface reactions, it has been shown that the long-term evolution of the core oscillator is decisively influenced by slow surface changes, such as progressing deactivation. Here we present an in-depth numerical investigation of the coupled slow and fast surface dynamics in an electrocatalytic oscillator. The model consists of four nonlinear coupled ordinary differential equations, investigated over a wide parameter range. Besides the conventional bifurcation analysis, the system was studied by means of high-resolution period and Lyapunov diagrams. It was observed that the bifurcation diagram changes considerably as the irreversible surface poisoning evolves, and the oscillatory region shrinks. The qualitative dynamics changes accordingly and the chaotic oscillations are dramatically suppressed. Nevertheless, periodic cascades are preserved in a confined region of the resistance vs. voltage diagram. Numerical results are compared to experiments published earlier and the latter reinterpreted. Finally, the comprehensive description of the time-evolution in the period and Lyapunov diagrams suggests further experimental studies correlating the evolution of the system's dynamics with changes of the catalyst structure.

  14. Fast recognition of musical sounds based on timbre.

    PubMed

    Agus, Trevor R; Suied, Clara; Thorpe, Simon J; Pressnitzer, Daniel

    2012-05-01

    Human listeners seem to have an impressive ability to recognize a wide variety of natural sounds. However, there is surprisingly little quantitative evidence to characterize this fundamental ability. Here the speed and accuracy of musical-sound recognition were measured psychophysically with a rich but acoustically balanced stimulus set. The set comprised recordings of notes from musical instruments and sung vowels. In a first experiment, reaction times were collected for three target categories: voice, percussion, and strings. In a go/no-go task, listeners reacted as quickly as possible to members of a target category while withholding responses to distractors (a diverse set of musical instruments). Results showed near-perfect accuracy and fast reaction times, particularly for voices. In a second experiment, voices were recognized among strings and vice-versa. Again, reaction times to voices were faster. In a third experiment, auditory chimeras were created to retain only spectral or temporal features of the voice. Chimeras were recognized accurately, but not as quickly as natural voices. Altogether, the data suggest rapid and accurate neural mechanisms for musical-sound recognition based on selectivity to complex spectro-temporal signatures of sound sources.

  15. Fast CEUS image segmentation based on self organizing maps

    NASA Astrophysics Data System (ADS)

    Paire, Julie; Sauvage, Vincent; Albouy-Kissi, Adelaïde; Ladam Marcus, Viviane; Marcus, Claude; Hoeffel, Christine

    2014-03-01

    Contrast-enhanced ultrasound (CEUS) has recently become an important technology for lesion detection and characterization. CEUS is used to investigate the perfusion kinetics in tissue over time, which relates to tissue vascularization. In this paper, we present an interactive segmentation method based on the neural networks, which enables to segment malignant tissue over CEUS sequences. We use Self-Organizing-Maps (SOM), an unsupervised neural network, to project high dimensional data to low dimensional space, named a map of neurons. The algorithm gathers the observations in clusters, respecting the topology of the observations space. This means that a notion of neighborhood between classes is defined. Adjacent observations in variables space belong to the same class or related classes after classification. Thanks to this neighborhood conservation property and associated with suitable feature extraction, this map provides user friendly segmentation tool. It will assist the expert in tumor segmentation with fast and easy intervention. We implement SOM on a Graphics Processing Unit (GPU) to accelerate treatment. This allows a greater number of iterations and the learning process to converge more precisely. We get a better quality of learning so a better classification. Our approach allows us to identify and delineate lesions accurately. Our results show that this method improves markedly the recognition of liver lesions and opens the way for future precise quantification of contrast enhancement.

  16. [Fast discrimination of edible vegetable oil based on Raman spectroscopy].

    PubMed

    Zhou, Xiu-Jun; Dai, Lian-Kui; Li, Sheng

    2012-07-01

    A novel method to fast discriminate edible vegetable oils by Raman spectroscopy is presented. The training set is composed of different edible vegetable oils with known classes. Based on their original Raman spectra, baseline correction and normalization were applied to obtain standard spectra. Two characteristic peaks describing the unsaturated degree of vegetable oil were selected as feature vectors; then the centers of all classes were calculated. For an edible vegetable oil with unknown class, the same pretreatment and feature extraction methods were used. The Euclidian distances between the feature vector of the unknown sample and the center of each class were calculated, and the class of the unknown sample was finally determined by the minimum distance. For 43 edible vegetable oil samples from seven different classes, experimental results show that the clustering effect of each class was more obvious and the class distance was much larger with the new feature extraction method compared with PCA. The above classification model can be applied to discriminate unknown edible vegetable oils rapidly and accurately.

  17. Fast Minimum Variance Beamforming Based on Legendre Polynomials.

    PubMed

    Bae, MooHo; Park, Sung Bae; Kwon, Sung Jae

    2016-09-01

    Currently, minimum variance beamforming (MV) is actively investigated as a method that can improve the performance of an ultrasound beamformer, in terms of the lateral and contrast resolution. However, this method has the disadvantage of excessive computational complexity since the inverse spatial covariance matrix must be calculated. Some noteworthy methods among various attempts to solve this problem include beam space adaptive beamforming methods and the fast MV method based on principal component analysis, which are similar in that the original signal in the element space is transformed to another domain using an orthonormal basis matrix and the dimension of the covariance matrix is reduced by approximating the matrix only with important components of the matrix, hence making the inversion of the matrix very simple. Recently, we proposed a new method with further reduced computational demand that uses Legendre polynomials as the basis matrix for such a transformation. In this paper, we verify the efficacy of the proposed method through Field II simulations as well as in vitro and in vivo experiments. The results show that the approximation error of this method is less than or similar to those of the above-mentioned methods and that the lateral response of point targets and the contrast-to-speckle noise in anechoic cysts are also better than or similar to those methods when the dimensionality of the covariance matrices is reduced to the same dimension.

  18. Nanorod-Based Fast-Response Pressure-Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy; VanderWal, Randall

    2007-01-01

    A proposed program of research and development would be devoted to exploitation of nanomaterials in pressuresensitive paints (PSPs), which are used on wind-tunnel models for mapping surface pressures associated with flow fields. Heretofore, some success has been achieved in measuring steady-state pressures by use of PSPs, but success in measuring temporally varying pressures has been elusive because of the inherent slowness of the optical responses of these materials. A PSP contains a dye that luminesces in a suitable wavelength range in response to photoexcitation in a shorter wavelength range. The luminescence is quenched by oxygen at a rate proportional to the partial pressure of oxygen and thus proportional to the pressure of air. As a result, the intensity of luminescence varies inversely with the pressure of air. The major problem in developing a PSP that could be easily applied to a wind-tunnel model and could be useful for measuring rapidly varying pressure is to provide very high gas diffusivity for rapid, easy transport of oxygen to and from active dye molecules. Most PSPs include polymer-base binders, which limit the penetration of oxygen to dye molecules, thereby reducing responses to pressure fluctuations. The proposed incorporation of nanomaterials (somewhat more specifically, nanorods) would result in paints having nanostructured surfaces that, relative to conventional PSP surfaces, would afford easier and more nearly complete access of oxygen molecules to dye molecules. One measure of greater access is effective surface area: For a typical PSP as proposed applied to a given solid surface, the nanometer-scale structural features would result in an exposed surface area more than 100 times that of a conventional PSP, and the mass of proposed PSP needed to cover the surface would be less than tenth of the mass of the conventional PSP. One aspect of the proposed development would be to synthesize nanorods of Si/SiO2, in both tangle-mat and regular- array

  19. Remote vibration measurement: A wireless passive surface acoustic wave resonator fast probing strategy

    NASA Astrophysics Data System (ADS)

    Friedt, J.-M.; Droit, C.; Ballandras, S.; Alzuaga, S.; Martin, G.; Sandoz, P.

    2012-05-01

    Surface acoustic wave (SAW) resonators can advantageously operate as passive sensors which can be interrogated through a wireless link. Amongst the practical applications of such devices, structural health monitoring through stress measurement and more generally vibration characteristics of mechanical structures benefit from the ability to bury such sensors within the considered structure (wireless and battery-less). However, measurement bandwidth becomes a significant challenge when measuring wideband vibration characteristics of mechanical structures. A fast SAW resonator measurement scheme is demonstrated here. The measurement bandwidth is limited by the physical settling time of the resonator (Q/π periods), requiring only two probe pulses through a monostatic RADAR-like electronic setup to identify the sensor resonance frequency and hence stress on a resonator acting as a strain gauge. A measurement update rate of 4800 Hz using a high quality factor SAW resonator operating in the 434 MHz Industrial, Scientific and Medical band is experimentally demonstrated.

  20. Remote vibration measurement: a wireless passive surface acoustic wave resonator fast probing strategy.

    PubMed

    Friedt, J-M; Droit, C; Ballandras, S; Alzuaga, S; Martin, G; Sandoz, P

    2012-05-01

    Surface acoustic wave (SAW) resonators can advantageously operate as passive sensors which can be interrogated through a wireless link. Amongst the practical applications of such devices, structural health monitoring through stress measurement and more generally vibration characteristics of mechanical structures benefit from the ability to bury such sensors within the considered structure (wireless and battery-less). However, measurement bandwidth becomes a significant challenge when measuring wideband vibration characteristics of mechanical structures. A fast SAW resonator measurement scheme is demonstrated here. The measurement bandwidth is limited by the physical settling time of the resonator (Q/π periods), requiring only two probe pulses through a monostatic RADAR-like electronic setup to identify the sensor resonance frequency and hence stress on a resonator acting as a strain gauge. A measurement update rate of 4800 Hz using a high quality factor SAW resonator operating in the 434 MHz Industrial, Scientific and Medical band is experimentally demonstrated.

  1. Fast three-dimensional measurements for dynamic scenes with shiny surfaces

    NASA Astrophysics Data System (ADS)

    Feng, Shijie; Chen, Qian; Zuo, Chao; Asundi, Anand

    2017-01-01

    This paper presents a novel fringe projection technique for fast three-dimensional (3-D) shape measurements of moving highly reflective objects. By combining the standard three-step phase-shifting fringe patterns with a digital speckle image, dynamic 3-D reconstructions of shiny surfaces can be efficiently achieved with only four projected patterns. The phase measurement is performed by three-step phase-shifting algorithm as it uses the theoretical minimum number of fringe patterns for phase-shifting profilometry. To avoid the camera saturation, a dual-camera fringe projection system is built to measure shiny objects from two different directions. The erroneous phase obtained from a saturated pixel is corrected by the phase of its corresponding pixel in the other view which is free from the saturation problem. To achieve high measurement accuracy, the corresponding high light intensity areas in cameras are found by sub-pixel matches of the speckle pattern in either view. Benefited from the trifocal tensor constraint, the corresponding points in the two wrapped phase maps can be directly established, and thus, the difficulties in determining the correct fringe order for the discontinuous or isolated surfaces can be effectively bypassed. Experimental results indicate that the proposed method is able to successfully measure highly reflective surfaces for both stationary and dynamic scenes.

  2. A fast and reliable readout method for quantitative analysis of surface-enhanced Raman scattering nanoprobes on chip surface

    NASA Astrophysics Data System (ADS)

    Chang, Hyejin; Kang, Homan; Jeong, Sinyoung; Ko, Eunbyeol; Lee, Yoon-Sik; Lee, Ho-Young; Jeong, Dae Hong

    2015-05-01

    Surface-enhanced Raman scattering techniques have been widely used for bioanalysis due to its high sensitivity and multiplex capacity. However, the point-scanning method using a micro-Raman system, which is the most common method in the literature, has a disadvantage of extremely long measurement time for on-chip immunoassay adopting a large chip area of approximately 1-mm scale and confocal beam point of ca. 1-μm size. Alternative methods such as sampled spot scan with high confocality and large-area scan method with enlarged field of view and low confocality have been utilized in order to minimize the measurement time practically. In this study, we analyzed the two methods in respect of signal-to-noise ratio and sampling-led signal fluctuations to obtain insights into a fast and reliable readout strategy. On this basis, we proposed a methodology for fast and reliable quantitative measurement of the whole chip area. The proposed method adopted a raster scan covering a full area of 100 μm × 100 μm region as a proof-of-concept experiment while accumulating signals in the CCD detector for single spectrum per frame. One single scan with 10 s over 100 μm × 100 μm area yielded much higher sensitivity compared to sampled spot scanning measurements and no signal fluctuations attributed to sampled spot scan. This readout method is able to serve as one of key technologies that will bring quantitative multiplexed detection and analysis into practice.

  3. A fast and reliable readout method for quantitative analysis of surface-enhanced Raman scattering nanoprobes on chip surface

    SciTech Connect

    Chang, Hyejin; Jeong, Sinyoung; Ko, Eunbyeol; Jeong, Dae Hong E-mail: debobkr@gmail.com; Kang, Homan; Lee, Yoon-Sik E-mail: debobkr@gmail.com; Lee, Ho-Young E-mail: debobkr@gmail.com

    2015-05-15

    Surface-enhanced Raman scattering techniques have been widely used for bioanalysis due to its high sensitivity and multiplex capacity. However, the point-scanning method using a micro-Raman system, which is the most common method in the literature, has a disadvantage of extremely long measurement time for on-chip immunoassay adopting a large chip area of approximately 1-mm scale and confocal beam point of ca. 1-μm size. Alternative methods such as sampled spot scan with high confocality and large-area scan method with enlarged field of view and low confocality have been utilized in order to minimize the measurement time practically. In this study, we analyzed the two methods in respect of signal-to-noise ratio and sampling-led signal fluctuations to obtain insights into a fast and reliable readout strategy. On this basis, we proposed a methodology for fast and reliable quantitative measurement of the whole chip area. The proposed method adopted a raster scan covering a full area of 100 μm × 100 μm region as a proof-of-concept experiment while accumulating signals in the CCD detector for single spectrum per frame. One single scan with 10 s over 100 μm × 100 μm area yielded much higher sensitivity compared to sampled spot scanning measurements and no signal fluctuations attributed to sampled spot scan. This readout method is able to serve as one of key technologies that will bring quantitative multiplexed detection and analysis into practice.

  4. A Randomized Field Trial of the Fast ForWord Language Computer-Based Training Program

    ERIC Educational Resources Information Center

    Borman, Geoffrey D.; Benson, James G.; Overman, Laura

    2009-01-01

    This article describes an independent assessment of the Fast ForWord Language computer-based training program developed by Scientific Learning Corporation. Previous laboratory research involving children with language-based learning impairments showed strong effects on their abilities to recognize brief and fast sequences of nonspeech and speech…

  5. Design and development of a profilometer for the fast and accurate characterization of optical surfaces

    NASA Astrophysics Data System (ADS)

    Gómez-Pedrero, José A.; Rodríguez-Ibañez, Diego; Alonso, José; Quirgoa, Juan A.

    2015-09-01

    With the advent of techniques devised for the mass production of optical components made with surfaces of arbitrary form (also known as free form surfaces) in the last years, a parallel development of measuring systems adapted for these new kind of surfaces constitutes a real necessity for the industry. Profilometry is one of the preferred methods for the assessment of the quality of a surface, and is widely employed in the optical fabrication industry for the quality control of its products. In this work, we present the design, development and assembly of a new profilometer with five axis of movement, specifically suited to the measurement of medium size (up to 150 mm of diameter) "free-form" optical surfaces with sub-micrometer accuracy and low measuring times. The apparatus is formed by three X, Y, Z linear motorized positioners plus and additional angular and a tilt positioner employed to locate accurately the surface to be measured and the probe which can be a mechanical or an optical one, being optical one a confocal sensor based on chromatic aberration. Both optical and mechanical probes guarantee an accuracy lower than the micrometer in the determination of the surface height, thus ensuring an accuracy in the surface curvatures of the order of 0.01 D or better. An original calibration procedure based on the measurement of a precision sphere has been developed in order to correct the perpendicularity error between the axes of the linear positioners. To reduce the measuring time of the profilometer, a custom electronics, based on an Arduino™ controller, have been designed and produced in order to synchronize the five motorized positioners and the optical and mechanical probes so that a medium size surface (around 10 cm of diameter) with a dynamic range in curvatures of around 10 D, can be measured in less than 300 seconds (using three axes) keeping the resolution in height and curvature in the figures mentioned above.

  6. A fast direct matrix solver for surface integral equation methods for electromagnetic wave scattering from non-penetrable targets

    NASA Astrophysics Data System (ADS)

    Wei, Jian-Gong; Peng, Zhen; Lee, Jin-Fa

    2012-10-01

    The implementation details of a fast direct solver is described herein for solving dense matrix equations from the application of surface integral equation methods for electromagnetic field scatterings from non-penetrable targets. The proposed algorithm exploits the smoothness of the far field and computes a low rank decomposition of the off-diagonal coupling blocks of the matrices through a set of skeletonization processes. Moreover, an artificial surface (the Huygens' surface) is introduced for each clustering group to efficiently account for the couplings between well-separated groups. Furthermore, a recursive multilevel version of the algorithm is presented. Although asymptotically the algorithm would not alter the bleak outlook of the complexity of the worst case scenario,O(N3) for required CPU time where N denotes the number of unknowns, for electrically large electromagnetic (EM) problems; through numerical examples, we found that the proposed multilevel direct solver can scale as good as O(N1.3) in memory consumption and O(N1.8) in CPU time for moderate-sized EM problems. Note that our conclusions are drawn based on a few sample examples that we have conducted and should not be taken as a true complexity analysis for general electrodynamic applications. However, for the fixed frequency (h-refinement) scenario, where the discretization size decreases, the computational complexities observed agree well with the theoretical predictions. Namely, the algorithm exhibits O(N) and O(N1.5) complexities for memory consumption and CPU time, respectively.

  7. Source estimation with surface-related multiples—fast ambiguity-resolved seismic imaging

    NASA Astrophysics Data System (ADS)

    Tu, Ning; Aravkin, Aleksandr; van Leeuwen, Tristan; Lin, Tim; Herrmann, Felix J.

    2016-06-01

    We address the problem of obtaining a reliable seismic image without prior knowledge of the source wavelet, especially from data that contain strong surface-related multiples. Conventional reverse-time migration requires prior knowledge of the source wavelet, which is either technically or computationally challenging to accurately determine; inaccurate estimates of the source wavelet can result in seriously degraded reverse-time migrated images, and therefore wrong geological interpretations. To solve this problem, we present a `wavelet-free' imaging procedure that simultaneously inverts for the source wavelet and the seismic image, by tightly integrating source estimation into a fast least-squares imaging framework, namely compressive imaging, given a reasonably accurate background velocity model. However, this joint inversion problem is difficult to solve as it is plagued with local minima and the ambiguity with respect to amplitude scalings because of the multiplicative, and therefore nonlinear, appearance of the source wavelet in the otherwise linear formalism. We have found a way to solve this nonlinear joint-inversion problem using a technique called variable projection, and a way to overcome the scaling ambiguity by including surface-related multiples in our imaging procedure following recent developments in surface-related multiple prediction by sparse inversion. As a result, we obtain without prior knowledge of the source wavelet high-resolution seismic images, comparable in quality to images obtained assuming the true source wavelet is known. By leveraging the computationally efficient compressive-imaging methodology, these results are obtained at affordable computational costs compared with conventional processing work flows that include surface-related multiple removal and reverse-time migration.

  8. Ultra-Fast Glyco-Coating of Non-Biological Surfaces

    PubMed Central

    Williams, Eleanor; Barr, Katie; Korchagina, Elena; Tuzikov, Alexander; Henry, Stephen; Bovin, Nicolai

    2016-01-01

    The ability to glycosylate surfaces has medical and diagnostic applications, but there is no technology currently recognized as being able to coat any surface without the need for prior chemical modification of the surface. Recently, a family of constructs called function-spacer-lipids (FSL) has been used to glycosylate cells. Because it is known that lipid-based material can adsorb onto surfaces, we explored the potential and performance of cell-labelling FSL constructs to “glycosylate” non-biological surfaces. Using blood group A antigen as an indicator, the performance of a several variations of FSL constructs to modify a large variety of non-biological surfaces was evaluated. It was found the FSL constructs when optimised could in a few seconds glycosylate almost any non-biological surface including metals, glass, plastics, rubbers and other polymers. Although the FSL glycan coating was non-covalent, and therefore temporary, it was sufficiently robust with appropriate selection of spacer and surface that it could capture anti-glycan antibodies, immobilize cells (via antibody), and withstand incubation in serum and extensive buffer washing, making it suitable for diagnostic and research applications. PMID:26784187

  9. Fast Object Motion Estimation Based on Dynamic Stixels

    PubMed Central

    Morales, Néstor; Morell, Antonio; Toledo, Jonay; Acosta, Leopoldo

    2016-01-01

    The stixel world is a simplification of the world in which obstacles are represented as vertical instances, called stixels, standing on a surface assumed to be planar. In this paper, previous approaches for stixel tracking are extended using a two-level scheme. In the first level, stixels are tracked by matching them between frames using a bipartite graph in which edges represent a matching cost function. Then, stixels are clustered into sets representing objects in the environment. These objects are matched based on the number of stixels paired inside them. Furthermore, a faster, but less accurate approach is proposed in which only the second level is used. Several configurations of our method are compared to an existing state-of-the-art approach to show how our methodology outperforms it in several areas, including an improvement in the quality of the depth reconstruction. PMID:27483265

  10. A ZnO nanowire-based photo-inverter with pulse-induced fast recovery

    NASA Astrophysics Data System (ADS)

    Ali Raza, Syed Raza; Lee, Young Tack; Hosseini Shokouh, Seyed Hossein; Ha, Ryong; Choi, Heon-Jin; Im, Seongil

    2013-10-01

    We demonstrate a fast response photo-inverter comprised of one transparent gated ZnO nanowire field-effect transistor (FET) and one opaque FET respectively as the driver and load. Under ultraviolet (UV) light the transfer curve of the transparent gate FET shifts to the negative side and so does the voltage transfer curve (VTC) of the inverter. After termination of UV exposure the recovery of photo-induced current takes a long time in general. This persistent photoconductivity (PPC) is due to hole trapping on the surface of ZnO NWs. Here, we used a positive voltage short pulse after UV exposure, for the first time resolving the PPC issue in nanowire-based photo-detectors by accumulating electrons at the ZnO/dielectric interface. We found that a pulse duration as small as 200 ns was sufficient to reach a full recovery to the dark state from the UV induced state, realizing a fast UV detector with a voltage output.We demonstrate a fast response photo-inverter comprised of one transparent gated ZnO nanowire field-effect transistor (FET) and one opaque FET respectively as the driver and load. Under ultraviolet (UV) light the transfer curve of the transparent gate FET shifts to the negative side and so does the voltage transfer curve (VTC) of the inverter. After termination of UV exposure the recovery of photo-induced current takes a long time in general. This persistent photoconductivity (PPC) is due to hole trapping on the surface of ZnO NWs. Here, we used a positive voltage short pulse after UV exposure, for the first time resolving the PPC issue in nanowire-based photo-detectors by accumulating electrons at the ZnO/dielectric interface. We found that a pulse duration as small as 200 ns was sufficient to reach a full recovery to the dark state from the UV induced state, realizing a fast UV detector with a voltage output. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03801g

  11. Fast and slow responses of Southern Ocean sea surface temperature to SAM in coupled climate models

    NASA Astrophysics Data System (ADS)

    Kostov, Yavor; Marshall, John; Hausmann, Ute; Armour, Kyle C.; Ferreira, David; Holland, Marika M.

    2017-03-01

    We investigate how sea surface temperatures (SSTs) around Antarctica respond to the Southern Annular Mode (SAM) on multiple timescales. To that end we examine the relationship between SAM and SST within unperturbed preindustrial control simulations of coupled general circulation models (GCMs) included in the Climate Modeling Intercomparison Project phase 5 (CMIP5). We develop a technique to extract the response of the Southern Ocean SST (55°S-70°S) to a hypothetical step increase in the SAM index. We demonstrate that in many GCMs, the expected SST step response function is nonmonotonic in time. Following a shift to a positive SAM anomaly, an initial cooling regime can transition into surface warming around Antarctica. However, there are large differences across the CMIP5 ensemble. In some models the step response function never changes sign and cooling persists, while in other GCMs the SST anomaly crosses over from negative to positive values only 3 years after a step increase in the SAM. This intermodel diversity can be related to differences in the models' climatological thermal ocean stratification in the region of seasonal sea ice around Antarctica. Exploiting this relationship, we use observational data for the time-mean meridional and vertical temperature gradients to constrain the real Southern Ocean response to SAM on fast and slow timescales.

  12. Nonuniform fast Fourier transform-based fast back-projection algorithm for stepped frequency continuous wave ground penetrating radar imaging

    NASA Astrophysics Data System (ADS)

    Qu, Lele; Yin, Yuqing

    2016-10-01

    Stepped frequency continuous wave ground penetrating radar (SFCW-GPR) systems are becoming increasingly popular in the GPR community due to the wider dynamic range and higher immunity to radio interference. The traditional back-projection (BP) algorithm is preferable for SFCW-GPR imaging in layered mediums scenarios for its convenience and robustness. However, the existing BP imaging algorithms are usually very computationally intensive, which limits their practical applications to SFCW-GPR imaging. To solve the above problem, a fast SFCW-GPR BP imaging algorithm based on nonuniform fast Fourier transform (NUFFT) technique is proposed in this paper. By reformulating the traditional BP imaging algorithm into the evaluations of NUFFT, the computational efficiency of NUFFT is exploited to reduce the computational complexity of the imaging reconstruction. Both simulation and experimental results have verified the effectiveness and improvement of computational efficiency of the proposed imaging method.

  13. Application of Fast Dynamic Allan Variance for the Characterization of FOGs-Based Measurement While Drilling.

    PubMed

    Wang, Lu; Zhang, Chunxi; Gao, Shuang; Wang, Tao; Lin, Tie; Li, Xianmu

    2016-12-07

    The stability of a fiber optic gyroscope (FOG) in measurement while drilling (MWD) could vary with time because of changing temperature, high vibration, and sudden power failure. The dynamic Allan variance (DAVAR) is a sliding version of the Allan variance. It is a practical tool that could represent the non-stationary behavior of the gyroscope signal. Since the normal DAVAR takes too long to deal with long time series, a fast DAVAR algorithm has been developed to accelerate the computation speed. However, both the normal DAVAR algorithm and the fast algorithm become invalid for discontinuous time series. What is worse, the FOG-based MWD underground often keeps working for several days; the gyro data collected aboveground is not only very time-consuming, but also sometimes discontinuous in the timeline. In this article, on the basis of the fast algorithm for DAVAR, we make a further advance in the fast algorithm (improved fast DAVAR) to extend the fast DAVAR to discontinuous time series. The improved fast DAVAR and the normal DAVAR are used to responsively characterize two sets of simulation data. The simulation results show that when the length of the time series is short, the improved fast DAVAR saves 78.93% of calculation time. When the length of the time series is long ( 6 × 10 5 samples), the improved fast DAVAR reduces calculation time by 97.09%. Another set of simulation data with missing data is characterized by the improved fast DAVAR. Its simulation results prove that the improved fast DAVAR could successfully deal with discontinuous data. In the end, a vibration experiment with FOGs-based MWD has been implemented to validate the good performance of the improved fast DAVAR. The results of the experience testify that the improved fast DAVAR not only shortens computation time, but could also analyze discontinuous time series.

  14. Application of Fast Dynamic Allan Variance for the Characterization of FOGs-Based Measurement While Drilling

    PubMed Central

    Wang, Lu; Zhang, Chunxi; Gao, Shuang; Wang, Tao; Lin, Tie; Li, Xianmu

    2016-01-01

    The stability of a fiber optic gyroscope (FOG) in measurement while drilling (MWD) could vary with time because of changing temperature, high vibration, and sudden power failure. The dynamic Allan variance (DAVAR) is a sliding version of the Allan variance. It is a practical tool that could represent the non-stationary behavior of the gyroscope signal. Since the normal DAVAR takes too long to deal with long time series, a fast DAVAR algorithm has been developed to accelerate the computation speed. However, both the normal DAVAR algorithm and the fast algorithm become invalid for discontinuous time series. What is worse, the FOG-based MWD underground often keeps working for several days; the gyro data collected aboveground is not only very time-consuming, but also sometimes discontinuous in the timeline. In this article, on the basis of the fast algorithm for DAVAR, we make a further advance in the fast algorithm (improved fast DAVAR) to extend the fast DAVAR to discontinuous time series. The improved fast DAVAR and the normal DAVAR are used to responsively characterize two sets of simulation data. The simulation results show that when the length of the time series is short, the improved fast DAVAR saves 78.93% of calculation time. When the length of the time series is long (6×105 samples), the improved fast DAVAR reduces calculation time by 97.09%. Another set of simulation data with missing data is characterized by the improved fast DAVAR. Its simulation results prove that the improved fast DAVAR could successfully deal with discontinuous data. In the end, a vibration experiment with FOGs-based MWD has been implemented to validate the good performance of the improved fast DAVAR. The results of the experience testify that the improved fast DAVAR not only shortens computation time, but could also analyze discontinuous time series. PMID:27941600

  15. Surface water mass composition changes captured by cores of Arctic land-fast sea ice

    NASA Astrophysics Data System (ADS)

    Smith, I. J.; Eicken, H.; Mahoney, A. R.; Van Hale, R.; Gough, A. J.; Fukamachi, Y.; Jones, J.

    2016-04-01

    In the Arctic, land-fast sea ice growth can be influenced by fresher water from rivers and residual summer melt. This paper examines a method to reconstruct changes in water masses using oxygen isotope measurements of sea ice cores. To determine changes in sea water isotope composition over the course of the ice growth period, the output of a sea ice thermodynamic model (driven with reanalysis data, observations of snow depth, and freeze-up dates) is used along with sea ice oxygen isotope measurements and an isotopic fractionation model. Direct measurements of sea ice growth rates are used to validate the output of the sea ice growth model. It is shown that for sea ice formed during the 2011/2012 ice growth season at Barrow, Alaska, large changes in isotopic composition of the ocean waters were captured by the sea ice isotopic composition. Salinity anomalies in the ocean were also tracked by moored instruments. These data indicate episodic advection of meteoric water, having both lower salinity and lower oxygen isotopic composition, during the winter sea ice growth season. Such advection of meteoric water during winter is surprising, as no surface meltwater and no local river discharge should be occurring at this time of year in that area. How accurately changes in water masses as indicated by oxygen isotope composition can be reconstructed using oxygen isotope analysis of sea ice cores is addressed, along with methods/strategies that could be used to further optimize the results. The method described will be useful for winter detection of meteoric water presence in Arctic fast ice regions, which is important for climate studies in a rapidly changing Arctic. Land-fast sea ice effective fractionation coefficients were derived, with a range of +1.82‰ to +2.52‰. Those derived effective fractionation coefficients will be useful for future water mass component proportion calculations. In particular, the equations given can be used to inform choices made when

  16. Accurate Anisotropic Fast Marching for Diffusion-Based Geodesic Tractography

    PubMed Central

    Jbabdi, S.; Bellec, P.; Toro, R.; Daunizeau, J.; Pélégrini-Issac, M.; Benali, H.

    2008-01-01

    Using geodesics for inferring white matter fibre tracts from diffusion-weighted MR data is an attractive method for at least two reasons: (i) the method optimises a global criterion, and hence is less sensitive to local perturbations such as noise or partial volume effects, and (ii) the method is fast, allowing to infer on a large number of connexions in a reasonable computational time. Here, we propose an improved fast marching algorithm to infer on geodesic paths. Specifically, this procedure is designed to achieve accurate front propagation in an anisotropic elliptic medium, such as DTI data. We evaluate the numerical performance of this approach on simulated datasets, as well as its robustness to local perturbation induced by fiber crossing. On real data, we demonstrate the feasibility of extracting geodesics to connect an extended set of brain regions. PMID:18299703

  17. High power, fast, microwave components based on beam generated plasmas

    NASA Astrophysics Data System (ADS)

    Manheimer, W. M.; Fernsler, R. F.; Gitlin, M. S.

    1998-10-01

    It is shown that the agile mirror plasma, under development as a device to simply and cheaply give electronic steering to microwave beams, also has application as a fast, electronically controlled, high power reflector, or phase shifter. In a radar system, this can lead to such applications as pulse to pulse polarization agility and electronic control of antenna gain, as well as to innovative approaches to high power millimeter wave circulators. The basic theory of the enhanced glow plasma is also developed.

  18. Fast ultrahigh-degree global spherical harmonic synthesis on nonequispaced grid points at irregular surfaces

    NASA Astrophysics Data System (ADS)

    Moazezi, Siamak; Zomorrodian, Hossein; Siahkoohi, Hamid Reza; Azmoudeh-Ardalan, Alireza; Gholami, Ali

    2016-09-01

    In this paper, we presented a fast unified method to compute the gravity field functionals and their directional derivatives up to arbitrary orders on nonequispaced grid points at irregular surfaces using ultrahigh-degree models. The direct spherical harmonic synthesis (SHS) for computing the gravity field functionals at arbitrary locations through the Legendre functions is a time-consuming task for high-order and -degree models. Besides, to compute the derivatives of SHS in terms of latitude, the derivatives of the Legendre functions are needed. Therefore, we used Fourier coefficients of Wigner d-functions to compute the directional derivatives of SHS up to arbitrary orders. We also showed that these functions and their derivatives up to order 2 are stable up to ultrahigh-degree 2^{14} = 16{,}384 using extended double precision (i.e., 80 bits variables). Although 2D-FFT can accelerate the computation of global SHS (GSHS), it restricts the results on equispaced grid points. Hence, we used the nonequispaced FFT (NFFT) for computing GSHS on irregular grid points on the sphere that it is the fast nonequispaced GSHS (NGSHS). For maximum degree N and computing points of {{O}}(N^2) with arbitrary locations, the direct computation methods have the complexity of {{O}}(N^4). But the presented algorithm with and without precomputed Fourier coefficients of Wigner d-functions has the complexity of {{O}}(N^2 log ^2 N + N^2 s^2) and {{O}}(N^3 + N^2 s^2), respectively, where s is cutoff parameter of convolution in NFFT. Using a convolution technique in frequency domain, the NGSHS on the ellipsoid was computed. For computation the gravity field functionals by the NGSHS at irregular surfaces, we defined the Taylor expansion and the Padé approximation both on the sphere and on the ellipsoid. The results showed that the constructed Padé approximation on the ellipsoid provides better accuracy. Finally, we showed that the introduced unified algorithm achieves the required accuracy

  19. Fast Dynamic Meshing Method Based on Delaunay Graph and Inverse Distance Weighting Interpolation

    NASA Astrophysics Data System (ADS)

    Wang, Yibin; Qin, Ning; Zhao, Ning

    2016-06-01

    A novel mesh deformation technique is developed based on the Delaunay graph mapping method and the inverse distance weighting (IDW) interpolation. The algorithm maintains the advantages of the efficiency of Delaunay-graph-mapping mesh deformation while possess the ability for better controlling the near surface mesh quality. The Delaunay graph is used to divide the mesh domain into a number of sub-domains. On each of the sub-domains, the inverse distance weighting interpolation is applied to build a much smaller sized translation matrix between the original mesh and the deformed mesh, resulting a similar efficiency for the mesh deformation as compared to the fast Delaunay graph mapping method. The paper will show how the near-wall mesh quality is controlled and improved by the new method while the computational time is compared with the original Delaunay graph mapping method.

  20. Fast spot-based multiscale simulations of granular drainage

    SciTech Connect

    Rycroft, Chris H.; Wong, Yee Lok; Bazant, Martin Z.

    2009-05-22

    We develop a multiscale simulation method for dense granular drainage, based on the recently proposed spot model, where the particle packing flows by local collective displacements in response to diffusing"spots'" of interstitial free volume. By comparing with discrete-element method (DEM) simulations of 55,000 spheres in a rectangular silo, we show that the spot simulation is able to approximately capture many features of drainage, such as packing statistics, particle mixing, and flow profiles. The spot simulation runs two to three orders of magnitude faster than DEM, making it an appropriate method for real-time control or optimization. We demonstrateextensions for modeling particle heaping and avalanching at the free surface, and for simulating the boundary layers of slower flow near walls. We show that the spot simulations are robust and flexible, by demonstrating that they can be used in both event-driven and fixed timestep approaches, and showing that the elastic relaxation step used in the model can be applied much less frequently and still create good results.

  1. A ZnO nanowire-based photo-inverter with pulse-induced fast recovery.

    PubMed

    Raza, Syed Raza Ali; Lee, Young Tack; Hosseini Shokouh, Seyed Hossein; Ha, Ryong; Choi, Heon-Jin; Im, Seongil

    2013-11-21

    We demonstrate a fast response photo-inverter comprised of one transparent gated ZnO nanowire field-effect transistor (FET) and one opaque FET respectively as the driver and load. Under ultraviolet (UV) light the transfer curve of the transparent gate FET shifts to the negative side and so does the voltage transfer curve (VTC) of the inverter. After termination of UV exposure the recovery of photo-induced current takes a long time in general. This persistent photoconductivity (PPC) is due to hole trapping on the surface of ZnO NWs. Here, we used a positive voltage short pulse after UV exposure, for the first time resolving the PPC issue in nanowire-based photo-detectors by accumulating electrons at the ZnO/dielectric interface. We found that a pulse duration as small as 200 ns was sufficient to reach a full recovery to the dark state from the UV induced state, realizing a fast UV detector with a voltage output.

  2. Fast phase unwrapping algorithm based on region partition for structured light vision measurement

    NASA Astrophysics Data System (ADS)

    Lu, Jun; Su, Hang

    2014-04-01

    Phase unwrapping is a key problem of phase-shifting profilometry vision measurement for complex object surface shapes. The simple path-following phase unwrapping algorithm is fast but has serious unwrapping error for complex shapes. The Goldstein+flood phase unwrapping algorithm can handle some complex shape object measurement; however, it is time consuming. We propose a fast phase unwrapping algorithm based on region partition according to a quality map of wrapped phase. In this algorithm, wrapped phase image is divided into several regions using partition thresholds, which are determined according to histogram of quality value. Each region is unwrapped by using a simple path-following phase algorithm and several groups with different priorities are generated. These groups are merged according to their priorities from high to low order and a final absolute phase is obtained. The proposed method is applied to wrapped phase images of three objects with and without noise. Experiments show that the proposed method is much faster, more accurate, and robust to noise than the Goldstein+flood algorithm in unwrapping complex phase image.

  3. Fast interactive integration of cross-sectional image datasets and surface data for morphometric analysis.

    PubMed

    Meruvia-Pastor, Oscar; Soh, Jung; Xiao, Mei; Schmidt, Eric; Logan, Cairine; Boughner, Julia C; Jones, Nicholas; Osborn, David; Santiago, Johanna; Gittleman, Julian; Hallgrímsson, Benedikt; Sensen, Christoph W

    2009-01-01

    To investigate external facial morphology and cell proliferation patterns and their relationship with cleft lip malformation in mice, we need to compare samples of mice tissue photographs and surface reconstructions from micro-CT scans obtained from mouse embryos. Tissue samples obtained through digital photography are typically misaligned with respect to each other, which prevents further analysis. We have developed a system for fast interactive alignment of these image stacks for volume reconstruction and data visualization and analysis in 3D. The system is designed to work in multiprocessor environments and can utilize an arbitrary number of processors, cutting down significantly the turnaround time and allowing users to quickly process sets of hundreds of high resolution images using a combination of automated and interactive tools. Additional modules are used to reconstruct the shape of the original subject. Our system is interactive, fully scalable and can be applied to any photographic sliced dataset, regardless of subject and reduces significantly the processing time for stack alignment.

  4. Fast simulated annealing inversion of surface waves on pavement using phase-velocity spectra

    USGS Publications Warehouse

    Ryden, N.; Park, C.B.

    2006-01-01

    The conventional inversion of surface waves depends on modal identification of measured dispersion curves, which can be ambiguous. It is possible to avoid mode-number identification and extraction by inverting the complete phase-velocity spectrum obtained from a multichannel record. We use the fast simulated annealing (FSA) global search algorithm to minimize the difference between the measured phase-velocity spectrum and that calculated from a theoretical layer model, including the field setup geometry. Results show that this algorithm can help one avoid getting trapped in local minima while searching for the best-matching layer model. The entire procedure is demonstrated on synthetic and field data for asphalt pavement. The viscoelastic properties of the top asphalt layer are taken into account, and the inverted asphalt stiffness as a function of frequency compares well with laboratory tests on core samples. The thickness and shear-wave velocity of the deeper embedded layers are resolved within 10% deviation from those values measured separately during pavement construction. The proposed method may be equally applicable to normal soil site investigation and in the field of ultrasonic testing of materials. ?? 2006 Society of Exploration Geophysicists.

  5. Pole Photogrammetry with AN Action Camera for Fast and Accurate Surface Mapping

    NASA Astrophysics Data System (ADS)

    Gonçalves, J. A.; Moutinho, O. F.; Rodrigues, A. C.

    2016-06-01

    High resolution and high accuracy terrain mapping can provide height change detection for studies of erosion, subsidence or land slip. A UAV flying at a low altitude above the ground, with a compact camera, acquires images with resolution appropriate for these change detections. However, there may be situations where different approaches may be needed, either because higher resolution is required or the operation of a drone is not possible. Pole photogrammetry, where a camera is mounted on a pole, pointing to the ground, is an alternative. This paper describes a very simple system of this kind, created for topographic change detection, based on an action camera. These cameras have high quality and very flexible image capture. Although radial distortion is normally high, it can be treated in an auto-calibration process. The system is composed by a light aluminium pole, 4 meters long, with a 12 megapixel GoPro camera. Average ground sampling distance at the image centre is 2.3 mm. The user moves along a path, taking successive photos, with a time lapse of 0.5 or 1 second, and adjusting the speed in order to have an appropriate overlap, with enough redundancy for 3D coordinate extraction. Marked ground control points are surveyed with GNSS for precise georeferencing of the DSM and orthoimage that are created by structure from motion processing software. An average vertical accuracy of 1 cm could be achieved, which is enough for many applications, for example for soil erosion. The GNSS survey in RTK mode with permanent stations is now very fast (5 seconds per point), which results, together with the image collection, in a very fast field work. If an improved accuracy is needed, since image resolution is 1/4 cm, it can be achieved using a total station for the control point survey, although the field work time increases.

  6. A FAST ITERATIVE METHOD FOR SOLVING THE EIKONAL EQUATION ON TRIANGULATED SURFACES.

    PubMed

    Fu, Zhisong; Jeong, Won-Ki; Pan, Yongsheng; Kirby, Robert M; Whitaker, Ross T

    2011-01-01

    This paper presents an efficient, fine-grained parallel algorithm for solving the Eikonal equation on triangular meshes. The Eikonal equation, and the broader class of Hamilton-Jacobi equations to which it belongs, have a wide range of applications from geometric optics and seismology to biological modeling and analysis of geometry and images. The ability to solve such equations accurately and efficiently provides new capabilities for exploring and visualizing parameter spaces and for solving inverse problems that rely on such equations in the forward model. Efficient solvers on state-of-the-art, parallel architectures require new algorithms that are not, in many cases, optimal, but are better suited to synchronous updates of the solution. In previous work [W. K. Jeong and R. T. Whitaker, SIAM J. Sci. Comput., 30 (2008), pp. 2512-2534], the authors proposed the fast iterative method (FIM) to efficiently solve the Eikonal equation on regular grids. In this paper we extend the fast iterative method to solve Eikonal equations efficiently on triangulated domains on the CPU and on parallel architectures, including graphics processors. We propose a new local update scheme that provides solutions of first-order accuracy for both architectures. We also propose a novel triangle-based update scheme and its corresponding data structure for efficient irregular data mapping to parallel single-instruction multiple-data (SIMD) processors. We provide detailed descriptions of the implementations on a single CPU, a multicore CPU with shared memory, and SIMD architectures with comparative results against state-of-the-art Eikonal solvers.

  7. A FAST ITERATIVE METHOD FOR SOLVING THE EIKONAL EQUATION ON TRIANGULATED SURFACES*

    PubMed Central

    Fu, Zhisong; Jeong, Won-Ki; Pan, Yongsheng; Kirby, Robert M.; Whitaker, Ross T.

    2012-01-01

    This paper presents an efficient, fine-grained parallel algorithm for solving the Eikonal equation on triangular meshes. The Eikonal equation, and the broader class of Hamilton–Jacobi equations to which it belongs, have a wide range of applications from geometric optics and seismology to biological modeling and analysis of geometry and images. The ability to solve such equations accurately and efficiently provides new capabilities for exploring and visualizing parameter spaces and for solving inverse problems that rely on such equations in the forward model. Efficient solvers on state-of-the-art, parallel architectures require new algorithms that are not, in many cases, optimal, but are better suited to synchronous updates of the solution. In previous work [W. K. Jeong and R. T. Whitaker, SIAM J. Sci. Comput., 30 (2008), pp. 2512–2534], the authors proposed the fast iterative method (FIM) to efficiently solve the Eikonal equation on regular grids. In this paper we extend the fast iterative method to solve Eikonal equations efficiently on triangulated domains on the CPU and on parallel architectures, including graphics processors. We propose a new local update scheme that provides solutions of first-order accuracy for both architectures. We also propose a novel triangle-based update scheme and its corresponding data structure for efficient irregular data mapping to parallel single-instruction multiple-data (SIMD) processors. We provide detailed descriptions of the implementations on a single CPU, a multicore CPU with shared memory, and SIMD architectures with comparative results against state-of-the-art Eikonal solvers. PMID:22641200

  8. A portable intra-oral scanner based on sinusoidal pattern of fast phase-shifting

    NASA Astrophysics Data System (ADS)

    Jan, Chia-Ming; Lin, Ying-Chieh

    2016-03-01

    This paper presented our current research about the intra-oral scanner made by MIRDC. Utilizing the sinusoidal pattern for fast phase-shifting technique to deal with 3D digitalization of human dental surface profile, the development of pseudo-phase shifting digital projection can easily achieve one type of full-field scanning instead of the common technique of the laser line scanning. Based on traditional Moiré method, we adopt projecting fringes and retrieve phase reconstruction to forward phase unwrapping. The phase difference between the plane and object can be exactly calculated from the desired fringe images, and the surface profile of object was probably reconstructed by using the phase differences information directly. According to our algorithm of space mapping between projections and capturing orientation exchange of our intra-oral scanning configuration, the system we made certainly can be proved to achieve the required accuracy of +/-10μm to deal with intra-oral scanning on the basis of utilizing active triangulation method. The final purpose aimed to the scanning of object surface profile with its size about 10x10x10mm3.

  9. AN EFFICIENT HIGHER-ORDER FAST MULTIPOLE BOUNDARY ELEMENT SOLUTION FOR POISSON-BOLTZMANN BASED MOLECULAR ELECTROSTATICS

    PubMed Central

    Bajaj, Chandrajit; Chen, Shun-Chuan; Rand, Alexander

    2011-01-01

    In order to compute polarization energy of biomolecules, we describe a boundary element approach to solving the linearized Poisson-Boltzmann equation. Our approach combines several important features including the derivative boundary formulation of the problem and a smooth approximation of the molecular surface based on the algebraic spline molecular surface. State of the art software for numerical linear algebra and the kernel independent fast multipole method is used for both simplicity and efficiency of our implementation. We perform a variety of computational experiments, testing our method on a number of actual proteins involved in molecular docking and demonstrating the effectiveness of our solver for computing molecular polarization energy. PMID:21660123

  10. Vision-based fast navigation of micro aerial vehicles

    NASA Astrophysics Data System (ADS)

    Loianno, Giuseppe; Kumar, Vijay

    2016-05-01

    We address the key challenges for autonomous fast flight for Micro Aerial Vehicles (MAVs) in 3-D, cluttered environments. For complete autonomy, the system must identify the vehicle's state at high rates, using either absolute or relative asynchronous on-board sensor measurements, use these state estimates for feedback control, and plan trajectories to the destination. State estimation requires information from different sensors to be fused, exploiting information from different, possible asynchronous sensors at different rates. In this work, we present techniques in the area of planning, control and visual-inertial state estimation for fast navigation of MAVs. We demonstrate how to solve on-board, on a small computational unit, the pose estimation, control and planning problems for MAVs, using a minimal sensor suite for autonomous navigation composed of a single camera and IMU. Additionally, we show that a consumer electronic device such as a smartphone can alternatively be employed for both sensing and computation. Experimental results validate the proposed techniques. Any consumer, provided with a smartphone, can autonomously drive a quadrotor platform at high speed, without GPS, and concurrently build 3-D maps, using a suitably designed app.

  11. Research of Fast 3D Imaging Based on Multiple Mode

    NASA Astrophysics Data System (ADS)

    Chen, Shibing; Yan, Huimin; Ni, Xuxiang; Zhang, Xiuda; Wang, Yu

    2016-02-01

    Three-dimensional (3D) imaging has received increasingly extensive attention and has been widely used currently. Lots of efforts have been put on three-dimensional imaging method and system study, in order to meet fast and high accurate requirement. In this article, we realize a fast and high quality stereo matching algorithm on field programmable gate array (FPGA) using the combination of time-of-flight (TOF) camera and binocular camera. Images captured from the two cameras own a same spatial resolution, letting us use the depth maps taken by the TOF camera to figure initial disparity. Under the constraint of the depth map as the stereo pairs when comes to stereo matching, expected disparity of each pixel is limited within a narrow search range. In the meanwhile, using field programmable gate array (FPGA, altera cyclone IV series) concurrent computing we can configure multi core image matching system, thus doing stereo matching on embedded system. The simulation results demonstrate that it can speed up the process of stereo matching and increase matching reliability and stability, realize embedded calculation, expand application range.

  12. Surface activation-based nanobonding and interconnection at room temperature

    NASA Astrophysics Data System (ADS)

    Howlader, M. M. R.; Yamauchi, A.; Suga, T.

    2011-02-01

    Flip chip nanobonding and interconnect system (NBIS) equipment with high precision alignment has been developed based on the surface activated bonding method for high-density interconnection and MEMS packaging. The 3σ alignment accuracy in the IR transmission system was approximately ±0.2 µm. The performance of the NBIS has been preliminarily investigated through bonding between relatively rough surfaces of copper through silicon vias (Cu-TSVs) and gold-stud bumps (Au-SBs), and smooth surfaces of silicon wafers. The Cu-TSVs of 55 µm diameter and the Au-SBs of 35 µm diameter with ~6-10 nm surface roughness (RMS) were bonded at room temperature after surface activation using an argon fast atom beam (Ar-FAB) under 0.16 N per bump. Silicon wafers of 50 mm diameter with ~0.2 nm RMS surface roughness were bonded without heating after surface activation. Void-free interfaces both in Cu-TSV/Au-SB and silicon/silicon with bonding strength equivalent to bulk fracture of Au and silicon, respectively, were achieved. A few nm thick amorphous layers were observed across the silicon/silicon interface that was fabricated by the Ar-FAB. This study in the interconnection and bonding facilitates the required three-dimensional integration on the same surface for high-density electronic and biomedical systems.

  13. [CUDA-based fast dose calculation in radiotherapy].

    PubMed

    Wang, Xianliang; Liu, Cao; Hou, Qing

    2011-10-01

    Dose calculation plays a key role in treatment planning of radiotherapy. Algorithms for dose calculation require high accuracy and computational efficiency. Finite size pencil beam (FSPB) algorithm is a method commonly adopted in the treatment planning system for radiotherapy. However, improvement on its computational efficiency is still desirable for such purpose as real time treatment planning. In this paper, we present an implementation of the FSPB, by which the most time-consuming parts in the algorithm are parallelized and ported on graphic processing unit (GPU). Compared with the FSPB completely running on central processing unit (CPU), the GPU-implemented FSPB can speed up the dose calculation for 25-35 times on a low price GPU (Geforce GT320) and for 55-100 times on a Tesla C1060, indicating that the GPU-implemented FSPB can provide fast enough dose calculations for real-time treatment planning.

  14. Surface-Enhanced Separation of Water from Hydrocarbons: Potential Dewatering Membranes for the Catalytic Fast Pyrolysis of Pine Biomass

    DOE PAGES

    Engtrakul, Dr. Chaiwat; Hu, Michael Z.; Bischoff, Brian L; ...

    2016-01-01

    The impact of surface-selective coatings on water permeation through a membrane when exposed to catalytic fast pyrolysis (CFP) vapor products was studied by tailoring the surface properties of the membrane coating from superhydrophilic to superhydrophobic. Our approach utilized high-performance architectured surface-selective (HiPAS) membranes that were inserted after a CFP reactor. At this insertion point, the inner wall surface of a tubular membrane was exposed to a mixture of water and upgraded product vapors, including light gases and deoxygenated hydrocarbons. Under proper membrane operating conditions, a high selectivity for water over 1-ring upgraded biomass pyrolysis hydrocarbons was observed due to amore » surface-enhanced capillary condensation process. Owing to this surface-enhanced effect, HiPAS membranes have the potential to enable high flux separations suggesting that water can be selectively removed from the CFP product vapors.« less

  15. Surface-Enhanced Separation of Water from Hydrocarbons: Potential Dewatering Membranes for the Catalytic Fast Pyrolysis of Pine Biomass

    SciTech Connect

    Engtrakul, Dr. Chaiwat; Hu, Michael Z.; Bischoff, Brian L; Jang, Gyoung Gug

    2016-01-01

    The impact of surface-selective coatings on water permeation through a membrane when exposed to catalytic fast pyrolysis (CFP) vapor products was studied by tailoring the surface properties of the membrane coating from superhydrophilic to superhydrophobic. Our approach utilized high-performance architectured surface-selective (HiPAS) membranes that were inserted after a CFP reactor. At this insertion point, the inner wall surface of a tubular membrane was exposed to a mixture of water and upgraded product vapors, including light gases and deoxygenated hydrocarbons. Under proper membrane operating conditions, a high selectivity for water over 1-ring upgraded biomass pyrolysis hydrocarbons was observed due to a surface-enhanced capillary condensation process. Owing to this surface-enhanced effect, HiPAS membranes have the potential to enable high flux separations suggesting that water can be selectively removed from the CFP product vapors.

  16. Surface-Enhanced Separation of Water from Hydrocarbons: Potential Dewatering Membranes for the Catalytic Fast Pyrolysis of Pine Biomass

    SciTech Connect

    Engtrakul, Chaiwat; Hu, Michael Z.; Bischoff, Brian L.; Jang, Gyoung G.

    2016-10-20

    The impact of surface-selective coatings on water permeation through a membrane when exposed to catalytic fast pyrolysis (CFP) vapor products was studied by tailoring the surface properties of the membrane coating from superhydrophilic to superhydrophobic. Our approach used high-performance architectured surface-selective (HiPAS) membranes that were inserted after a CFP reactor. At this insertion point, the inner wall surface of a tubular membrane was exposed to a mixture of water and upgraded product vapors, including light gases and deoxygenated hydrocarbons. Under proper membrane operating conditions, a high selectivity for water over one-ring upgraded biomass pyrolysis hydrocarbons was observed as a result of a surface-enhanced capillary condensation process. Owing to this surface-enhanced effect, HiPAS membranes have the potential to enable high flux separations, suggesting that water can be selectively removed from the CFP product vapors.

  17. From FAST to E-FAST: an overview of the evolution of ultrasound-based traumatic injury assessment.

    PubMed

    Montoya, J; Stawicki, S P; Evans, D C; Bahner, D P; Sparks, S; Sharpe, R P; Cipolla, J

    2016-04-01

    Ultrasound is a ubiquitous and versatile diagnostic tool. In the setting of acute injury, ultrasound enhances the basic trauma evaluation, influences bedside decision-making, and helps determine whether or not an unstable patient requires emergent procedural intervention. Consequently, continued education of surgeons and other acute care practitioners in performing focused emergency ultrasound is of great importance. This article provides a synopsis of focused assessment with sonography for trauma (FAST) and the extended FAST (E-FAST) that incorporates basic thoracic injury assessment. The authors also review key pitfalls, limitations, controversies, and advances related to FAST, E-FAST, and ultrasound education.

  18. Platinum recycling going green via induced surface potential alteration enabling fast and efficient dissolution.

    PubMed

    Hodnik, Nejc; Baldizzone, Claudio; Polymeros, George; Geiger, Simon; Grote, Jan-Philipp; Cherevko, Serhiy; Mingers, Andrea; Zeradjanin, Aleksandar; Mayrhofer, Karl J J

    2016-10-21

    The recycling of precious metals, for example, platinum, is an essential aspect of sustainability for the modern industry and energy sectors. However, due to its resistance to corrosion, platinum-leaching techniques rely on high reagent consumption and hazardous processes, for example, boiling aqua regia; a mixture of concentrated nitric and hydrochloric acid. Here we demonstrate that complete dissolution of metallic platinum can be achieved by induced surface potential alteration, an 'electrode-less' process utilizing alternatively oxidative and reductive gases. This concept for platinum recycling exploits the so-called transient dissolution mechanism, triggered by a repetitive change in platinum surface oxidation state, without using any external electric current or electrodes. The effective performance in non-toxic low-concentrated acid and at room temperature is a strong benefit of this approach, potentially rendering recycling of industrial catalysts, including but not limited to platinum-based systems, more sustainable.

  19. Platinum recycling going green via induced surface potential alteration enabling fast and efficient dissolution

    PubMed Central

    Hodnik, Nejc; Baldizzone, Claudio; Polymeros, George; Geiger, Simon; Grote, Jan-Philipp; Cherevko, Serhiy; Mingers, Andrea; Zeradjanin, Aleksandar; Mayrhofer, Karl J. J.

    2016-01-01

    The recycling of precious metals, for example, platinum, is an essential aspect of sustainability for the modern industry and energy sectors. However, due to its resistance to corrosion, platinum-leaching techniques rely on high reagent consumption and hazardous processes, for example, boiling aqua regia; a mixture of concentrated nitric and hydrochloric acid. Here we demonstrate that complete dissolution of metallic platinum can be achieved by induced surface potential alteration, an ‘electrode-less' process utilizing alternatively oxidative and reductive gases. This concept for platinum recycling exploits the so-called transient dissolution mechanism, triggered by a repetitive change in platinum surface oxidation state, without using any external electric current or electrodes. The effective performance in non-toxic low-concentrated acid and at room temperature is a strong benefit of this approach, potentially rendering recycling of industrial catalysts, including but not limited to platinum-based systems, more sustainable. PMID:27767178

  20. Platinum recycling going green via induced surface potential alteration enabling fast and efficient dissolution

    NASA Astrophysics Data System (ADS)

    Hodnik, Nejc; Baldizzone, Claudio; Polymeros, George; Geiger, Simon; Grote, Jan-Philipp; Cherevko, Serhiy; Mingers, Andrea; Zeradjanin, Aleksandar; Mayrhofer, Karl J. J.

    2016-10-01

    The recycling of precious metals, for example, platinum, is an essential aspect of sustainability for the modern industry and energy sectors. However, due to its resistance to corrosion, platinum-leaching techniques rely on high reagent consumption and hazardous processes, for example, boiling aqua regia; a mixture of concentrated nitric and hydrochloric acid. Here we demonstrate that complete dissolution of metallic platinum can be achieved by induced surface potential alteration, an `electrode-less' process utilizing alternatively oxidative and reductive gases. This concept for platinum recycling exploits the so-called transient dissolution mechanism, triggered by a repetitive change in platinum surface oxidation state, without using any external electric current or electrodes. The effective performance in non-toxic low-concentrated acid and at room temperature is a strong benefit of this approach, potentially rendering recycling of industrial catalysts, including but not limited to platinum-based systems, more sustainable.

  1. (abstract) A Low-Cost Mission to 2060 Chiron Based on the Pluto Fast Flyby

    NASA Technical Reports Server (NTRS)

    Stern, S. A.; Salvo, C. G.; Wallace, R. A.; Weinstein, S. S.; Weissman, P. R.

    1994-01-01

    The Pluto Fast Flyby-based mission to Chiron described in this paper is a low cost, scientifically rewarding, focused mission in the outer solar system. The proposed mission will make a flyby of 2060 Chiron, an active 'comet' with over 10(sup 4) times the mass of Halley, and an eccentric, Saturn-crossing orbit which ranges from 8.5 to 19 AU. This mission concept achieves the flyby 4.2 years after launch on a direct trajectory from Earth, is independent of Jupiter launch windows, and fits within Discovery cost guidelines. This mission offers the scientific opportunity to examine a class of object left unsampled by the trail-blazing Mariners, Pioneers, Voyagers, and missions to Halley. Spacecraft reconnaissance of Chiron addresses unique objectives relating to cometary science, other small bodies, the structure of quasi-bound atmospheres on modest-sized bodies, and the origin of primitive bodies and the giant planets. Owing to Chiron's large size (180surface morphology, surface composition, internal structure, surface activity (including the nature of Chiron's outbursts), and origin. Engineering analysis indicates that the spacecraft is capable of navigating to and encountering Chiron at close approach distances of less than 5 000 km, well inside the 50 000 to 150 000 km coma, and perhaps within the collisional chemistry zone of the coma. The low cost of the proposed Chiron mission is based on the opportunity to use the planned Pluto Flyby spare spacecraft and a Proton Expendable Launch Vehicle (ELV) (the pluto spacecraft is being designed to be compatible with a Proton launch). Backup

  2. Fast Numerical Algorithms for 3-D Scattering from PEC and Dielectric Random Rough Surfaces in Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Lisha

    We present fast and robust numerical algorithms for 3-D scattering from perfectly electrical conducting (PEC) and dielectric random rough surfaces in microwave remote sensing. The Coifman wavelets or Coiflets are employed to implement Galerkin's procedure in the method of moments (MoM). Due to the high-precision one-point quadrature, the Coiflets yield fast evaluations of the most off-diagonal entries, reducing the matrix fill effort from O(N2) to O( N). The orthogonality and Riesz basis of the Coiflets generate well conditioned impedance matrix, with rapid convergence for the conjugate gradient solver. The resulting impedance matrix is further sparsified by the matrix-formed standard fast wavelet transform (SFWT). By properly selecting multiresolution levels of the total transformation matrix, the solution precision can be enhanced while matrix sparsity and memory consumption have not been noticeably sacrificed. The unified fast scattering algorithm for dielectric random rough surfaces can asymptotically reduce to the PEC case when the loss tangent grows extremely large. Numerical results demonstrate that the reduced PEC model does not suffer from ill-posed problems. Compared with previous publications and laboratory measurements, good agreement is observed.

  3. Fast gain and phase recovery of semiconductor optical amplifiers based on submonolayer quantum dots

    SciTech Connect

    Herzog, Bastian Owschimikow, Nina; Kaptan, Yücel; Kolarczik, Mirco; Switaiski, Thomas; Woggon, Ulrike; Schulze, Jan-Hindrik; Rosales, Ricardo; Strittmatter, André; Bimberg, Dieter; Pohl, Udo W.

    2015-11-16

    Submonolayer quantum dots as active medium in opto-electronic devices promise to combine the high density of states of quantum wells with the fast recovery dynamics of self-assembled quantum dots. We investigate the gain and phase recovery dynamics of a semiconductor optical amplifier based on InAs submonolayer quantum dots in the regime of linear operation by one- and two-color heterodyne pump-probe spectroscopy. We find an as fast recovery dynamics as for quantum dot-in-a-well structures, reaching 2 ps at moderate injection currents. The effective quantum well embedding the submonolayer quantum dots acts as a fast and efficient carrier reservoir.

  4. Devices based on surface plasmon interference filters

    NASA Technical Reports Server (NTRS)

    Wang, Yu (Inventor)

    2001-01-01

    Devices based on surface plasmon filters having at least one metal-dielectric interface to support surface plasmon waves. A multi-layer-coupled surface plasmon notch filter is provided to have more than two symmetric metal-dielectric interfaces coupled with one another to produce a transmission spectral window with desired spectral profile and bandwidth. Such notch filters can form various color filtering devices for color flat panel displays.

  5. A Fast Method of Deriving the Kirchhoff Formula for Moving Surfaces

    NASA Technical Reports Server (NTRS)

    Farassat, F.; Posey, Joe W.

    2007-01-01

    The Kirchhoff formula for a moving surface is very useful in many wave propagation problems, particularly in the prediction of noise from rotating machinery. Several publications in the last two decades have presented derivations of the Kirchhoff formula for moving surfaces in both time and frequency domains. Here we present a method originally developed by Farassat and Myers in time domain that is both simple and direct. It is based on generalized function theory and the useful concept of imbedding the problem in the unbounded three-dimensional space. We derive an inhomogeneous wave equation with the source terms that involve Dirac delta functions with their supports on the moving data surface. This wave equation is then solved using the simple free space Green's function of the wave equation resulting in the Kirchhoff formula. The algebraic manipulations are minimal and simple. We do not need the Green's theorem in four dimensions and there is no ambiguity in the interpretation of any terms in the final formulas. Furthermore, this method also gives the simplest derivation of the classical Kirchhoff formula which has a fairly lengthy derivation in physics and applied mathematics books. The Farassat-Myers method can be used easily in frequency domain.

  6. Fast Numerically Based Modeling for Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Sassen, D. S.; Everett, M. E.

    2007-05-01

    There is a need for computationally fast GPR numerical modeling. This includes circumstances where real time performance is needed, for example discrimination of landmines or UXO's, and in circumstances that require a high number of successive forward problems, for example inversion or imaging. Traditional numerical techniques such as finite difference or finite element are too slow for these applications, but they provide results from general scenarios such as scattering from very complicated shapes with high contrast. Neural networks may fit in the niche between analytical techniques and traditional numerical techniques. Our concept is training a neural network to associate the model inputs of electromagnetic properties of the background and targets, and the size and shape of the targets, with the output generated by a 3-D finite difference model. Successive examples from various electromagnetic properties and targets are displayed to the neural network, until the neural network has adapted itself though optimization. The trained neural network is now used as the forward model by displaying new input parameters and the neural network then generates the appropriate output. The results from the neural network are then compared to results from finite difference models to see how well the neural networks is performing and at what point it breaks down. Areas of poor fit can be addressed through further training. The neural network GPR model can be adapted by displaying additional finite difference results to the neural network, and can also be adapted to a specific field area by actual field data examples. Because of this adaptation ability the neural network GPR model can be optimized for specific environments and applications.

  7. Nanoparticle Based Surface-Enhanced Raman Spectroscopy

    SciTech Connect

    Talley, C E; Huser, T R; Hollars, C W; Jusinski, L; Laurence, T; Lane, S M

    2005-01-03

    Surface-enhanced Raman scattering is a powerful tool for the investigation of biological samples. Following a brief introduction to Raman and surface-enhanced Raman scattering, several examples of biophotonic applications of SERS are discussed. The concept of nanoparticle based sensors using SERS is introduced and the development of these sensors is discussed.

  8. Generalized Temporal Acceleration Scheme for Kinetic Monte Carlo Simulations of Surface Catalytic Processes by Scaling the Rates of Fast Reactions.

    PubMed

    Dybeck, Eric Christopher; Plaisance, Craig Patrick; Neurock, Matthew

    2017-02-14

    A novel algorithm has been developed to achieve temporal acceleration during kinetic Monte Carlo (KMC) simulations of surface catalytic processes. This algorithm allows for the direct simulation of reaction networks containing kinetic processes occurring on vastly disparate timescales which computationally overburden standard KMC methods. Previously developed methods for temporal acceleration in KMC have been designed for specific systems and often require a priori information from the user such as identifying the fast and slow processes. In the approach presented herein, quasi-equilibrated processes are identified automatically based on previous executions of the forward and reverse reactions. Temporal acceleration is achieved by automatically scaling the intrinsic rate constants of the quasi-equilibrated processes, bringing their rates closer to the timescales of the slow kinetically relevant non-equilibrated processes. All reactions are still simulated directly, although with modified rate constants. Abrupt changes in the underlying dynamics of the reaction network are identified during the simulation and the reaction rate constants are rescaled accordingly. The algorithm has been utilized here to model the Fischer-Tropsch synthesis reaction over ruthenium nanoparticles. This reaction network has multiple timescale-disparate processes which would be intractable to simulate without the aid of temporal acceleration. The accelerated simulations are found to give reaction rates and selectivities indistinguishable from those calculated by an equivalent mean-field kinetic model. The computational savings of the algorithm can span many orders of magnitude in realistic systems and the computational cost is not limited by the magnitude of the timescale disparity in the system processes. Furthermore, the algorithm has been designed in a generic fashion and can easily be applied to other surface catalytic processes of interest.

  9. Effects of fast halogen and plasma arc curing lights on the surface hardness of orthodontic adhesives for lingual retainers.

    PubMed

    Uşümez, Serdar; Büyükyilmaz, Tamer; Karaman, Ali Ihya

    2003-06-01

    The aims of this study were to (1) identify the optimum cure times of 2 different lingual retainer adhesives with a conventional halogen, a fast halogen, and a plasma arc light by measuring Vickers surface hardness, and (2) determine whether different lights produce similar surface hardness values for the same adhesive resin material. The investigated plasma arc curing unit was the PowerPac (American Dental Technologies, Corpus Christi, Tex), and the fast halogen unit was the Optilux 501 (Kerr, Orange, Calif). A conventional curing unit, the Ortholux XT (3M Dental Products, St. Paul, Minn) was used as the control. Two orthodontic lingual retainer adhesives were used: Transbond Lingual Retainer (3M Unitek, Monrovia, Calif) and Light Cure Retainer (Reliance Orthodontic Products, Itasca, Ill). Concise (3M Dental Products) and diluted Concise were used as controls. Transbond Lingual Retainer was polymerized by the PowerPac light in 6 seconds, by the Optilux in 10 seconds, and by the conventional halogen light in 20 seconds. The minimum curing times for Light Cure Retainer adhesive were 15 seconds for PowerPac, 10 seconds for Optilux, and 40 seconds for conventional halogen. Surface hardness values for each resin did not differ significantly with different curing units. However, different adhesives demonstrated significantly different surface hardness values. Final Vickers surface hardness values (averaged across curing units) of Transbond Lingual Retainer, Concise, diluted Concise, and Light Cure Retainer were 62.8, 52.4, 46.0, and 40.4, respectively. Plasma arc or fast halogen units polymerize resin composite adhesive in much shorter times than do conventional curing units, without a significant loss in surface hardness. Therefore, these units are suggested for clinical use to save chairside time.

  10. Comparative Evaluation of Vacuum-based Surface Sampling ...

    EPA Pesticide Factsheets

    Journal Article Following a biological contamination incident, collection of surface samples is necessary to determine the extent and level of contamination, and to deem an area safe for reentry upon decontamination. Current sampling strategies targeting Bacillus anthracis spores prescribe vacuum-based methods for rough and/or porous surfaces. In this study, four commonly-used B. anthracis spore sampling devices (vacuum socks, 37 mm 0.8 µm MCE filter cassettes, 37 mm 0.3 µm PTFE filter cassettes, and 3MTM forensic filters) were comparatively evaluated for their ability to recover surface-associated spores. The vacuum sock device was evaluated at two sampling speeds (slow and fast), resulting in five total methods evaluated. Aerosolized spores (~105 cm-2) of a surrogate Bacillus species (Bacillus atrophaeus) were allowed to settle onto three material types (concrete, carpet, and upholstery). Ten replicate samples were collected using each vacuum method, from each of the three material types. In addition, stainless steel (i.e., nonporous) surfaces inoculated simultaneously were sampled with pre-moistened wipes. Recoveries from wipes of steel surfaces were utilized to verify the inoculum, and to normalize vacuum-based recoveries across trials. Recovery (CFU cm-2) and relative recovery (vacuum recovery/wipe recovery) were determined for each method and material type. Relative recoveries were compared by one-way and three-way ANOVA. Data analysis by one-

  11. A fast and accurate FPGA based QRS detection system.

    PubMed

    Shukla, Ashish; Macchiarulo, Luca

    2008-01-01

    An accurate Field Programmable Gate Array (FPGA) based ECG Analysis system is described in this paper. The design, based on a popular software based QRS detection algorithm, calculates the threshold value for the next peak detection cycle, from the median of eight previously detected peaks. The hardware design has accuracy in excess of 96% in detecting the beats correctly when tested with a subset of five 30 minute data records obtained from the MIT-BIH Arrhythmia database. The design, implemented using a proprietary design tool (System Generator), is an extension of our previous work and uses 76% resources available in a small-sized FPGA device (Xilinx Spartan xc3s500), has a higher detection accuracy as compared to our previous design and takes almost half the analysis time in comparison to software based approach.

  12. Fast Marching Tree: a Fast Marching Sampling-Based Method for Optimal Motion Planning in Many Dimensions*

    PubMed Central

    Janson, Lucas; Schmerling, Edward; Clark, Ashley; Pavone, Marco

    2015-01-01

    In this paper we present a novel probabilistic sampling-based motion planning algorithm called the Fast Marching Tree algorithm (FMT*). The algorithm is specifically aimed at solving complex motion planning problems in high-dimensional configuration spaces. This algorithm is proven to be asymptotically optimal and is shown to converge to an optimal solution faster than its state-of-the-art counterparts, chiefly PRM* and RRT*. The FMT* algorithm performs a “lazy” dynamic programming recursion on a predetermined number of probabilistically-drawn samples to grow a tree of paths, which moves steadily outward in cost-to-arrive space. As such, this algorithm combines features of both single-query algorithms (chiefly RRT) and multiple-query algorithms (chiefly PRM), and is reminiscent of the Fast Marching Method for the solution of Eikonal equations. As a departure from previous analysis approaches that are based on the notion of almost sure convergence, the FMT* algorithm is analyzed under the notion of convergence in probability: the extra mathematical flexibility of this approach allows for convergence rate bounds—the first in the field of optimal sampling-based motion planning. Specifically, for a certain selection of tuning parameters and configuration spaces, we obtain a convergence rate bound of order O(n−1/d+ρ), where n is the number of sampled points, d is the dimension of the configuration space, and ρ is an arbitrarily small constant. We go on to demonstrate asymptotic optimality for a number of variations on FMT*, namely when the configuration space is sampled non-uniformly, when the cost is not arc length, and when connections are made based on the number of nearest neighbors instead of a fixed connection radius. Numerical experiments over a range of dimensions and obstacle configurations confirm our the-oretical and heuristic arguments by showing that FMT*, for a given execution time, returns substantially better solutions than either PRM* or RRT

  13. Protein-ligand recognition using spherical harmonic molecular surfaces: towards a fast and efficient filter for large virtual throughput screening.

    PubMed

    Cai, Wensheng; Shao, Xueguang; Maigret, Bernard

    2002-01-01

    Molecular surfaces are important because surface-shape complementarity is often a necessary condition in protein-ligand interactions and docking studies. We have previously described a fast and efficient method to obtain triangulated surface-meshes by topologically mapping ellipsoids on molecular surfaces. In this paper, we present an extension of our work to spherical harmonic surfaces in order to approximate molecular surfaces of both ligands and receptor-cavities and to easily check the surface-shape complementarity. The method consists of (1) finding lobes and holes on both ligand and cavity surfaces using contour maps of radius functions with spherical harmonic expansions, (2) superposing the surfaces around a given binding site by minimizing the distance between their respective expansion coefficients. This docking procedure capabilities was demonstrated by application to 35 protein-ligand complexes of known crystal structures. The method can also be easily and efficiently used as a filter to detect in a large conformational sampling the possible conformations presenting good complementarity with the receptor site, and being, therefore, good candidates for further more elaborate docking studies. This "virtual screening" was demonstrated on the platelet thrombin receptor.

  14. Visual saliency-based fast intracoding algorithm for high efficiency video coding

    NASA Astrophysics Data System (ADS)

    Zhou, Xin; Shi, Guangming; Zhou, Wei; Duan, Zhemin

    2017-01-01

    Intraprediction has been significantly improved in high efficiency video coding over H.264/AVC with quad-tree-based coding unit (CU) structure from size 64×64 to 8×8 and more prediction modes. However, these techniques cause a dramatic increase in computational complexity. An intracoding algorithm is proposed that consists of perceptual fast CU size decision algorithm and fast intraprediction mode decision algorithm. First, based on the visual saliency detection, an adaptive and fast CU size decision method is proposed to alleviate intraencoding complexity. Furthermore, a fast intraprediction mode decision algorithm with step halving rough mode decision method and early modes pruning algorithm is presented to selectively check the potential modes and effectively reduce the complexity of computation. Experimental results show that our proposed fast method reduces the computational complexity of the current HM to about 57% in encoding time with only 0.37% increases in BD rate. Meanwhile, the proposed fast algorithm has reasonable peak signal-to-noise ratio losses and nearly the same subjective perceptual quality.

  15. Micro-TLC Approach for Fast Screening of Environmental Samples Derived from Surface and Sewage Waters.

    PubMed

    Zarzycki, Paweł K; Slączka, Magdalena M; Włodarczyk, Elżbieta; Baran, Michał J

    2013-01-01

    In this work we demonstrated analytical capability of micro-planar (micro-TLC) technique comprising one and two-dimensional (2D) separation modes to generate fingerprints of environmental samples originated from sewage and ecosystems waters. We showed that elaborated separation and detection protocols are complementary to previously invented HPLC method based on temperature-dependent inclusion chromatography and UV-DAD detection. Presented 1D and 2D micro-TLC chromatograms of SPE (solid-phase extraction) extracts were optimized for fast and low-cost screening of water samples collected from lakes and rivers located in the area of Middle Pomerania in northern part of Poland. Moreover, we studied highly organic compounds loaded in the treated and untreated sewage waters obtained from municipal wastewater treatment plant "Jamno" near Koszalin City (Poland). Analyzed environmental samples contained number of substances characterized by polarity range from estetrol to progesterone as well as chlorophyll-related dyes previously isolated and pre-purified by simple SPE protocol involving C18 cartridges. Optimization of micro-TLC separation and quantification protocols of such samples were discussed from the practical point of view using simple separation efficiency criteria including total peaks number, log(product ΔhRF), signal intensity and peak asymmetry. Outcomes of the presented analytical approach, especially using detection involving direct fluorescence (UV366/Vis) and phosphomolybdic acid (PMA) visualization are compared with UV-DAD HPLC-generated data reported previously. Chemometric investigation based on principal components analysis revealed that SPE extracts separated by micro-TLC and detected under fluorescence and PMA visualization modes can be used for robust sample fingerprinting even after long-term storage of the extracts (up to 4 years) at subambient temperature (-20 °C). Such approach allows characterization of wide range of sample components that

  16. Nonlaser-based 3D surface imaging

    SciTech Connect

    Lu, Shin-yee; Johnson, R.K.; Sherwood, R.J.

    1994-11-15

    3D surface imaging refers to methods that generate a 3D surface representation of objects of a scene under viewing. Laser-based 3D surface imaging systems are commonly used in manufacturing, robotics and biomedical research. Although laser-based systems provide satisfactory solutions for most applications, there are situations where non laser-based approaches are preferred. The issues that make alternative methods sometimes more attractive are: (1) real-time data capturing, (2) eye-safety, (3) portability, and (4) work distance. The focus of this presentation is on generating a 3D surface from multiple 2D projected images using CCD cameras, without a laser light source. Two methods are presented: stereo vision and depth-from-focus. Their applications are described.

  17. Fast surface diffusion of amorphous o-terphenyl and its competition with viscous flow in surface evolution.

    PubMed

    Zhang, Wei; Brian, Caleb W; Yu, Lian

    2015-04-16

    Surface self-diffusion coefficients have been measured for the model molecular glass o-terphenyl (OTP) through surface-grating decay driven by capillarity. The decay mechanism transitions from viscous flow at high temperatures to surface diffusion at low temperatures; for 1000 nm wavelength gratings, the transition occurs at Tg + 11 K. The surface diffusion of OTP is 10(8) times faster than bulk diffusion at Tg and even faster at lower temperatures because of its weaker temperature dependence. At Tg, OTP has approximately the same bulk diffusivity as the previously studied molecular liquid indomethacin, but its surface diffusion is 100 times faster. While the molecular glass-formers exhibit transitions from viscous flow to surface diffusion as the mechanism of capillarity-driven surface flattening, polystyrenes and silicates show no such transition under comparable conditions, suggesting slower surface diffusion on these materials and a general dependence of surface diffusion on intermolecular forces. The velocity of surface crystal growth on molecular glasses is proportional to surface diffusivity, indicating a common kinetic barrier for both processes for temperatures below Tg.

  18. Fast Fragmentation of Networks Using Module-Based Attacks

    PubMed Central

    Requião da Cunha, Bruno; González-Avella, Juan Carlos; Gonçalves, Sebastián

    2015-01-01

    In the multidisciplinary field of Network Science, optimization of procedures for efficiently breaking complex networks is attracting much attention from a practical point of view. In this contribution, we present a module-based method to efficiently fragment complex networks. The procedure firstly identifies topological communities through which the network can be represented using a well established heuristic algorithm of community finding. Then only the nodes that participate of inter-community links are removed in descending order of their betweenness centrality. We illustrate the method by applying it to a variety of examples in the social, infrastructure, and biological fields. It is shown that the module-based approach always outperforms targeted attacks to vertices based on node degree or betweenness centrality rankings, with gains in efficiency strongly related to the modularity of the network. Remarkably, in the US power grid case, by deleting 3% of the nodes, the proposed method breaks the original network in fragments which are twenty times smaller in size than the fragments left by betweenness-based attack. PMID:26569610

  19. Fast Fragmentation of Networks Using Module-Based Attacks.

    PubMed

    Requião da Cunha, Bruno; González-Avella, Juan Carlos; Gonçalves, Sebastián

    2015-01-01

    In the multidisciplinary field of Network Science, optimization of procedures for efficiently breaking complex networks is attracting much attention from a practical point of view. In this contribution, we present a module-based method to efficiently fragment complex networks. The procedure firstly identifies topological communities through which the network can be represented using a well established heuristic algorithm of community finding. Then only the nodes that participate of inter-community links are removed in descending order of their betweenness centrality. We illustrate the method by applying it to a variety of examples in the social, infrastructure, and biological fields. It is shown that the module-based approach always outperforms targeted attacks to vertices based on node degree or betweenness centrality rankings, with gains in efficiency strongly related to the modularity of the network. Remarkably, in the US power grid case, by deleting 3% of the nodes, the proposed method breaks the original network in fragments which are twenty times smaller in size than the fragments left by betweenness-based attack.

  20. Whisker Contact Detection of Rodents Based on Slow and Fast Mechanical Inputs

    PubMed Central

    Claverie, Laure N.; Boubenec, Yves; Debrégeas, Georges; Prevost, Alexis M.; Wandersman, Elie

    2017-01-01

    Rodents use their whiskers to locate nearby objects with an extreme precision. To perform such tasks, they need to detect whisker/object contacts with a high temporal accuracy. This contact detection is conveyed by classes of mechanoreceptors whose neural activity is sensitive to either slow or fast time varying mechanical stresses acting at the base of the whiskers. We developed a biomimetic approach to separate and characterize slow quasi-static and fast vibrational stress signals acting on a whisker base in realistic exploratory phases, using experiments on both real and artificial whiskers. Both slow and fast mechanical inputs are successfully captured using a mechanical model of the whisker. We present and discuss consequences of the whisking process in purely mechanical terms and hypothesize that free whisking in air sets a mechanical threshold for contact detection. The time resolution and robustness of the contact detection strategies based on either slow or fast stress signals are determined. Contact detection based on the vibrational signal is faster and more robust to exploratory conditions than the slow quasi-static component, although both slow/fast components allow localizing the object. PMID:28119582

  1. Fast and sensitive trace analysis of malachite green using a surface-enhanced Raman microfluidic sensor.

    PubMed

    Lee, Sangyeop; Choi, Junghyun; Chen, Lingxin; Park, Byungchoon; Kyong, Jin Burm; Seong, Gi Hun; Choo, Jaebum; Lee, Yeonjung; Shin, Kyung-Hoon; Lee, Eun Kyu; Joo, Sang-Woo; Lee, Kyeong-Hee

    2007-05-08

    A rapid and highly sensitive trace analysis technique for determining malachite green (MG) in a polydimethylsiloxane (PDMS) microfluidic sensor was investigated using surface-enhanced Raman spectroscopy (SERS). A zigzag-shaped PDMS microfluidic channel was fabricated for efficient mixing between MG analytes and aggregated silver colloids. Under the optimal condition of flow velocity, MG molecules were effectively adsorbed onto silver nanoparticles while flowing along the upper and lower zigzag-shaped PDMS channel. A quantitative analysis of MG was performed based on the measured peak height at 1615 cm(-1) in its SERS spectrum. The limit of detection, using the SERS microfluidic sensor, was found to be below the 1-2 ppb level and this low detection limit is comparable to the result of the LC-Mass detection method. In the present study, we introduce a new conceptual detection technology, using a SERS microfluidic sensor, for the highly sensitive trace analysis of MG in water.

  2. Fast rule-based bioactivity prediction using associative classification mining

    PubMed Central

    2012-01-01

    Relating chemical features to bioactivities is critical in molecular design and is used extensively in the lead discovery and optimization process. A variety of techniques from statistics, data mining and machine learning have been applied to this process. In this study, we utilize a collection of methods, called associative classification mining (ACM), which are popular in the data mining community, but so far have not been applied widely in cheminformatics. More specifically, classification based on predictive association rules (CPAR), classification based on multiple association rules (CMAR) and classification based on association rules (CBA) are employed on three datasets using various descriptor sets. Experimental evaluations on anti-tuberculosis (antiTB), mutagenicity and hERG (the human Ether-a-go-go-Related Gene) blocker datasets show that these three methods are computationally scalable and appropriate for high speed mining. Additionally, they provide comparable accuracy and efficiency to the commonly used Bayesian and support vector machines (SVM) methods, and produce highly interpretable models. PMID:23176548

  3. Fast vision-based catheter 3D reconstruction.

    PubMed

    Moradi Dalvand, Mohsen; Nahavandi, Saeid; Howe, Robert D

    2016-07-21

    Continuum robots offer better maneuverability and inherent compliance and are well-suited for surgical applications as catheters, where gentle interaction with the environment is desired. However, sensing their shape and tip position is a challenge as traditional sensors can not be employed in the way they are in rigid robotic manipulators. In this paper, a high speed vision-based shape sensing algorithm for real-time 3D reconstruction of continuum robots based on the views of two arbitrary positioned cameras is presented. The algorithm is based on the closed-form analytical solution of the reconstruction of quadratic curves in 3D space from two arbitrary perspective projections. High-speed image processing algorithms are developed for the segmentation and feature extraction from the images. The proposed algorithms are experimentally validated for accuracy by measuring the tip position, length and bending and orientation angles for known circular and elliptical catheter shaped tubes. Sensitivity analysis is also carried out to evaluate the robustness of the algorithm. Experimental results demonstrate good accuracy (maximum errors of  ±0.6 mm and  ±0.5 deg), performance (200 Hz), and robustness (maximum absolute error of 1.74 mm, 3.64 deg for the added noises) of the proposed high speed algorithms.

  4. Fast vision-based catheter 3D reconstruction

    NASA Astrophysics Data System (ADS)

    Moradi Dalvand, Mohsen; Nahavandi, Saeid; Howe, Robert D.

    2016-07-01

    Continuum robots offer better maneuverability and inherent compliance and are well-suited for surgical applications as catheters, where gentle interaction with the environment is desired. However, sensing their shape and tip position is a challenge as traditional sensors can not be employed in the way they are in rigid robotic manipulators. In this paper, a high speed vision-based shape sensing algorithm for real-time 3D reconstruction of continuum robots based on the views of two arbitrary positioned cameras is presented. The algorithm is based on the closed-form analytical solution of the reconstruction of quadratic curves in 3D space from two arbitrary perspective projections. High-speed image processing algorithms are developed for the segmentation and feature extraction from the images. The proposed algorithms are experimentally validated for accuracy by measuring the tip position, length and bending and orientation angles for known circular and elliptical catheter shaped tubes. Sensitivity analysis is also carried out to evaluate the robustness of the algorithm. Experimental results demonstrate good accuracy (maximum errors of  ±0.6 mm and  ±0.5 deg), performance (200 Hz), and robustness (maximum absolute error of 1.74 mm, 3.64 deg for the added noises) of the proposed high speed algorithms.

  5. Ultra-fast cell counters based on microtubular waveguides

    PubMed Central

    Bausch, Cornelius S.; Heyn, Christian; Hansen, Wolfgang; Wolf, Insa M. A.; Diercks, Björn-Philipp; Guse, Andreas H.; Blick, Robert H.

    2017-01-01

    We present a radio-frequency impedance-based biosensor embedded inside a semiconductor microtube for the in-flow detection of single cells. An impedance-matched tank circuit and a tight wrapping of the electrodes around the sensing region, which creates a close, leakage current-free contact between cells and electrodes, yields a high signal-to-noise ratio. We experimentally show a twofold improved sensitivity of our three-dimensional electrode structure to conventional planar electrodes and support these findings by finite element simulations. Finally, we report on the differentiation of polystyrene beads, primary mouse T lymphocytes and Jurkat T lymphocytes using our device. PMID:28134293

  6. Ultra-fast cell counters based on microtubular waveguides

    NASA Astrophysics Data System (ADS)

    Bausch, Cornelius S.; Heyn, Christian; Hansen, Wolfgang; Wolf, Insa M. A.; Diercks, Björn-Philipp; Guse, Andreas H.; Blick, Robert H.

    2017-01-01

    We present a radio-frequency impedance-based biosensor embedded inside a semiconductor microtube for the in-flow detection of single cells. An impedance-matched tank circuit and a tight wrapping of the electrodes around the sensing region, which creates a close, leakage current-free contact between cells and electrodes, yields a high signal-to-noise ratio. We experimentally show a twofold improved sensitivity of our three-dimensional electrode structure to conventional planar electrodes and support these findings by finite element simulations. Finally, we report on the differentiation of polystyrene beads, primary mouse T lymphocytes and Jurkat T lymphocytes using our device.

  7. Fast Solvers for Transient Hydraulic Tomography based on Laplace transform

    NASA Astrophysics Data System (ADS)

    Bakhos, T.; Saibaba, A.; Kitanidis, P. K.

    2013-12-01

    Transient Hydraulic Tomography (THT) is a method to estimate the parameters hydraulic conductivity and specific storage, from measurements of hydraulic heads or pressure obtained in a series of interference tests in aquifer geologic formation such as an aquifer (i.e., pumping at one location and depth while measuring the response at several others). These measurements can be used to reconstruct the spatial variation of hydraulic parameters by solving a nonlinear inverse problem, which we tackle using the geostatistical approach. A central challenge associated with the application of the geostatistical approach to THT, is the computational cost associated with constructing the Jacobian - which represents the sensitivity of the measurements to the unknown parameters. This essentially requires repeated solutions to the 'forward problem' and the 'adjoint problem' for determination of derivatives, which are both time-dependent parabolic partial differential equations. To solve the 'forward problem', we use a Laplace Transform based exponential time integrator combined with a Krylov subspace based method for solving shifted systems. This approach allows us to independently evaluate the transient problem at different time instants at (almost) the cost of solving one steady-state groundwater equation. A similar approach can be used to accelerate the solution of the 'adjoint problem' as well. As we demonstrate, this approach dramatically lowers the computational cost associated with evaluating the Jacobian and as a result, the reconstruction of the parameters. The performance of our algorithm is demonstrated on some challenging synthetic examples; in particular, we apply it to large-scale inverse problems arising from transient hydraulic tomography.

  8. Fast magneto-optic switch based on nanosecond pulses

    NASA Astrophysics Data System (ADS)

    Weng, Zi-Hua; Ruan, Jian-Jian; Lin, Shao-Han; Chen, Zhi-Min

    2011-09-01

    The paper studies an all fiber high-speed magneto-optic switch which includes an optical route, a nanosecond pulse generator, and a magnetic field module in order to reduce the switching time of the optical switch in the all optical network. A compact nanosecond pulse generator can be designed based on the special character of the avalanche transistor. The output current pulse of the nanosecond pulse generator is less than 5 ns, while the pulse amplitude is more than 100 V and the pulse width is about 10 to 20 ns, which is able to drive a high-speed magnetic field. A solenoid is used as the magnetic field module, and a bismuth-substituted rare-earth iron garnet single crystal is chosen as the Faraday rotator. By changing the direction of current in the solenoid quickly, the magnetization of the magneto-optic material is reversed, and the optical beam can be rapidly switched. The experimental results indicate that the switching time of the device is about 100 to 400 ns, which can partially meet the demand of the rapid development of the all optical network.

  9. Fast Outlier Detection Using a Grid-Based Algorithm.

    PubMed

    Lee, Jihwan; Cho, Nam-Wook

    2016-01-01

    As one of data mining techniques, outlier detection aims to discover outlying observations that deviate substantially from the reminder of the data. Recently, the Local Outlier Factor (LOF) algorithm has been successfully applied to outlier detection. However, due to the computational complexity of the LOF algorithm, its application to large data with high dimension has been limited. The aim of this paper is to propose grid-based algorithm that reduces the computation time required by the LOF algorithm to determine the k-nearest neighbors. The algorithm divides the data spaces in to a smaller number of regions, called as a "grid", and calculates the LOF value of each grid. To examine the effectiveness of the proposed method, several experiments incorporating different parameters were conducted. The proposed method demonstrated a significant computation time reduction with predictable and acceptable trade-off errors. Then, the proposed methodology was successfully applied to real database transaction logs of Korea Atomic Energy Research Institute. As a result, we show that for a very large dataset, the grid-LOF can be considered as an acceptable approximation for the original LOF. Moreover, it can also be effectively used for real-time outlier detection.

  10. [Fast discrimination of varieties of sugar based on spectroscopy technology].

    PubMed

    Lin, Ping; Chen, Yong-Ming; He, Yong

    2009-02-01

    Visible and near-infrared reflectance spectroscopy (NIRS) was applied in the discrimination of sugar varieties. NIRS is a pollution-free, rapid, quantitative and qualitative analysis method, with the characteristics of high speed, non-destructiveness, high precision and reliable detection data, etc. Four kinds of sugar were gained from the local market and each species was divided into 40 samples. One hundred twenty samples were used as the training set and the remainders (total 40 samples) formed the prediction set. Samples were scanned by a spectroradiometer within a wavelength region of 325-1 075 nm. Three pre-processing methods were applied on the spectra prior to building the PLS regression model. The multivariable analysis using partial least square (PLS) was applied to abstract characteristics of the pattern. Through full cross validation, 11 principal components presenting important information of spectra were confirmed. The correlation coefficient (R), residual variance (Rv) and standard error of calibration (SEC) were 0.999 916, 0. 00 985 and 0.014 538 respectively. Then, these 11 principal components were taken as the input of BP neural network. This model was used to predict the varieties of 40 unknown samples. Through training and prediction, the recognition rate of 100% was achieved by BP neural network. This model has come to be reliable and practicable. Thus, it is concluded that PLS analysis combined with BP neural network is an available alternative for pattern recognition based on the spectroscopy technology.

  11. A fast smoothing algorithm for post-processing of surface reflectance spectra retrieved from airborne imaging spectrometer data.

    PubMed

    Gao, Bo-Cai; Liu, Ming

    2013-10-14

    Surface reflectance spectra retrieved from remotely sensed hyperspectral imaging data using radiative transfer models often contain residual atmospheric absorption and scattering effects. The reflectance spectra may also contain minor artifacts due to errors in radiometric and spectral calibrations. We have developed a fast smoothing technique for post-processing of retrieved surface reflectance spectra. In the present spectral smoothing technique, model-derived reflectance spectra are first fit using moving filters derived with a cubic spline smoothing algorithm. A common gain curve, which contains minor artifacts in the model-derived reflectance spectra, is then derived. This gain curve is finally applied to all of the reflectance spectra in a scene to obtain the spectrally smoothed surface reflectance spectra. Results from analysis of hyperspectral imaging data collected with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data are given. Comparisons between the smoothed spectra and those derived with the empirical line method are also presented.

  12. A Fast Smoothing Algorithm for Post-Processing of Surface Reflectance Spectra Retrieved from Airborne Imaging Spectrometer Data

    PubMed Central

    Gao, Bo-Cai; Liu, Ming

    2013-01-01

    Surface reflectance spectra retrieved from remotely sensed hyperspectral imaging data using radiative transfer models often contain residual atmospheric absorption and scattering effects. The reflectance spectra may also contain minor artifacts due to errors in radiometric and spectral calibrations. We have developed a fast smoothing technique for post-processing of retrieved surface reflectance spectra. In the present spectral smoothing technique, model-derived reflectance spectra are first fit using moving filters derived with a cubic spline smoothing algorithm. A common gain curve, which contains minor artifacts in the model-derived reflectance spectra, is then derived. This gain curve is finally applied to all of the reflectance spectra in a scene to obtain the spectrally smoothed surface reflectance spectra. Results from analysis of hyperspectral imaging data collected with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data are given. Comparisons between the smoothed spectra and those derived with the empirical line method are also presented. PMID:24129022

  13. Fast Surface Reconstruction and Segmentation with Terrestrial LiDAR Range Data

    DTIC Science & Technology

    2009-05-18

    SUPPLEMENTARY NOTES 14. ABSTRACT Recent advances in range measurement devices have opened up new opportunities and challenges for fast 3D modeling of...which are composed of partially ordered terrestrial range data. Our algorithms can be applied to a large class of LiDAR data acquisition systems, where...obtained by two different terrestrial acquisition systems. The first dataset contains 94 million points obtained by a vehicle-borne acquisition system

  14. Compressed sodium chloride as a fast-acting antimicrobial surface: results of a pilot study.

    PubMed

    Whitlock, B D; Smith, S W

    2016-10-01

    Antimicrobial surfaces are currently being studied as an aid to reduce transmission of pathogens leading to healthcare-associated infections (HAIs). Among the most harmful and costly pathogens that cause HAIs is meticillin-resistant Staphylococcus aureus (MRSA). Currently available and previously investigated antimicrobial surface technologies that are effective against MRSA (e.g. copper alloy surfaces) take 30min to several hours to achieve significant reduction. This article presents a new antimicrobial surface technology made of compressed sodium chloride that reduces MRSA 20-30 times faster than copper alloy surfaces.

  15. Power of surface-based DNA computation

    SciTech Connect

    Cai, Weiping; Condon, A.E.; Corn, R.M.

    1997-12-01

    A new model of DNA computation that is based on surface chemistry is studied. Such computations involve the manipulation of DNA strands that are immobilized on a surface, rather than in solution as in the work of Adleman. Surface-based chemistry has been a critical technology in many recent advances in biochemistry and offers several advantages over solution-based chemistry, including simplified handling of samples and elimination of loss of strands, which reduce error in the computation. The main contribution of this paper is in showing that in principle, surface-based DNA chemistry can efficiently support general circuit computation on many inputs in parallel. To do this, an abstract model of computation that allows parallel manipulation of binary inputs is described. It is then shown that this model can be implemented by encoding inputs as DNA strands and repeatedly modifying the strands in parallel on a surface, using the chemical processes of hybridization, exonuclease degradation, polymerase extension, and ligation. Thirdly, it is shown that the model supports efficient circuit simulation in the following sense: exactly those inputs that satisfy a circuit can be isolated and the number of parallel operations needed to do this is proportional to the size of the circuit. Finally, results are presented on the power of the model when another resource of DNA computation is limited, namely strand length. 12 refs.

  16. Combined experimental and theoretical study of fast atom diffraction on the β2(2×4) reconstructed GaAs(001) surface

    NASA Astrophysics Data System (ADS)

    Debiossac, M.; Zugarramurdi, A.; Khemliche, H.; Roncin, P.; Borisov, A. G.; Momeni, A.; Atkinson, P.; Eddrief, M.; Finocchi, F.; Etgens, V. H.

    2014-10-01

    A grazing incidence fast atom diffraction (GIFAD or FAD) setup, installed on a molecular beam epitaxy chamber, has been used to characterize the β2(2×4) reconstruction of a GaAs(001) surface at 530∘C under an As4 overpressure. Using a 400-eV 4He beam, high-resolution diffraction patterns with up to eighty well-resolved diffraction orders are observed simultaneously, providing a detailed fingerprint of the surface structure. Experimental diffraction data are in good agreement with results from quantum scattering calculations based on an ab initio projectile-surface interaction potential. Along with exact calculations, we show that a straightforward semiclassical analysis allows the features of the diffraction chart to be linked to the main characteristics of the surface reconstruction topography. Our results demonstrate that GIFAD is a technique suitable for measuring in situ the subtle details of complex surface reconstructions. We have performed measurements at very small incidence angles, where the kinetic energy of the projectile motion perpendicular to the surface can be reduced to less than 1 meV. This allowed the depth of the attractive van der Waals potential well to be estimated as -8.7 meV in very good agreement with results reported in literature.

  17. A surface ice module for wind turbine dynamic response simulation using FAST

    DOE PAGES

    Yu, Bingbin; Karr, Dale G.; Song, Huimin; ...

    2016-06-03

    It is a fact that developing offshore wind energy has become more and more serious worldwide in recent years. Many of the promising offshore wind farm locations are in cold regions that may have ice cover during wintertime. The challenge of possible ice loads on offshore wind turbines raises the demand of modeling capacity of dynamic wind turbine response under the joint action of ice, wind, wave, and current. The simulation software FAST is an open source computer-aided engineering (CAE) package maintained by the National Renewable Energy Laboratory. In this paper, a new module of FAST for assessing the dynamicmore » response of offshore wind turbines subjected to ice forcing is presented. In the ice module, several models are presented which involve both prescribed forcing and coupled response. For conditions in which the ice forcing is essentially decoupled from the structural response, ice forces are established from existing models for brittle and ductile ice failure. For conditions in which the ice failure and the structural response are coupled, such as lock-in conditions, a rate-dependent ice model is described, which is developed in conjunction with a new modularization framework for FAST. In this paper, analytical ice mechanics models are presented that incorporate ice floe forcing, deformation, and failure. For lower speeds, forces slowly build until the ice strength is reached and ice fails resulting in a quasi-static condition. For intermediate speeds, the ice failure can be coupled with the structural response and resulting in coinciding periods of the ice failure and the structural response. A third regime occurs at high speeds of encounter in which brittle fracturing of the ice feature occurs in a random pattern, which results in a random vibration excitation of the structure. An example wind turbine response is simulated under ice loading of each of the presented models. This module adds to FAST the capabilities for analyzing the response of wind

  18. A surface ice module for wind turbine dynamic response simulation using FAST

    SciTech Connect

    Yu, Bingbin; Karr, Dale G.; Song, Huimin; Sirnivas, Senu

    2016-06-03

    It is a fact that developing offshore wind energy has become more and more serious worldwide in recent years. Many of the promising offshore wind farm locations are in cold regions that may have ice cover during wintertime. The challenge of possible ice loads on offshore wind turbines raises the demand of modeling capacity of dynamic wind turbine response under the joint action of ice, wind, wave, and current. The simulation software FAST is an open source computer-aided engineering (CAE) package maintained by the National Renewable Energy Laboratory. In this paper, a new module of FAST for assessing the dynamic response of offshore wind turbines subjected to ice forcing is presented. In the ice module, several models are presented which involve both prescribed forcing and coupled response. For conditions in which the ice forcing is essentially decoupled from the structural response, ice forces are established from existing models for brittle and ductile ice failure. For conditions in which the ice failure and the structural response are coupled, such as lock-in conditions, a rate-dependent ice model is described, which is developed in conjunction with a new modularization framework for FAST. In this paper, analytical ice mechanics models are presented that incorporate ice floe forcing, deformation, and failure. For lower speeds, forces slowly build until the ice strength is reached and ice fails resulting in a quasi-static condition. For intermediate speeds, the ice failure can be coupled with the structural response and resulting in coinciding periods of the ice failure and the structural response. A third regime occurs at high speeds of encounter in which brittle fracturing of the ice feature occurs in a random pattern, which results in a random vibration excitation of the structure. An example wind turbine response is simulated under ice loading of each of the presented models. This module adds to FAST the capabilities for analyzing the response of wind

  19. Surface charge migration and dc surface flashover of surface-modified epoxy-based insulators

    NASA Astrophysics Data System (ADS)

    Li, Chuanyang; Hu, Jun; Lin, Chuanjie; Zhang, Boya; Zhang, Guixin; He, Jinliang

    2017-02-01

    Epoxy-based model insulators were manufactured and fluorinated under a F2/N2 mixture (12.5% F2) at 50 °C and 0.1 MPa for 15 min and 60 min. Surface charge accumulation and decay behavior were studied with and without dc voltage application. The effect of direct fluorination on surface charge migration as well as on flashover voltage was verified. The obtained results show that the charge decay of epoxy-based insulators is a slow process, but the decay rate increases when an outer dc electric field is applied. The surface charge distribution is changed when a streamer is triggered on the insulator surface. The existence of heteropolarity surface charges can decrease the dc surface flashover voltage to some extent, while the surface flashover voltage is almost unchanged when charges of the same polarity accumulate on the insulator surface. The short time fluorinated insulator can modify the surface resistivity, and the rate of surface charge dissipation is greatly increased under a dc electric field.

  20. Child and Parent Voices on a Community-Based Prevention Program (FAST)

    ERIC Educational Resources Information Center

    Fearnow-Kenney, Melodie; Hill, Patricia; Gore, Nicole

    2016-01-01

    Families and Schools Together (FAST) is a collaborative program involving schools, families, and community-based partners in efforts to prevent substance use, juvenile delinquency, school failure, child abuse and neglect, mental health problems, and violence. Although evaluated extensively, there remains a dearth of qualitative data on child and…

  1. Common and Specific Factors Approaches to Home-Based Treatment: I-FAST and MST

    ERIC Educational Resources Information Center

    Lee, Mo Yee; Greene, Gilbert J.; Fraser, J. Scott; Edwards, Shivani G.; Grove, David; Solovey, Andrew D.; Scott, Pamela

    2013-01-01

    Objectives: This study examined the treatment outcomes of integrated families and systems treatment (I-FAST), a moderated common factors approach, in reference to multisystemic therapy (MST), an established specific factor approach, for treating at risk children and adolescents and their families in an intensive community-based setting. Method:…

  2. Basic concepts underlying fast-neutron-based contraband interrogation technology. A systems viewpoint

    SciTech Connect

    Fink, C.L.; Guenther, P.T.; Smith, D.L.

    1992-12-01

    All accelerator-based fast-neutron contraband interrogation systems have many closely interrelated subsystems, whose performance parameters will be critically interdependent. For optimal overall performance, a systems analysis design approach is required. This paper provides a general overview of the interrelationships and the tradeoffs to be considered for optimization of nonaccelerator subsystems.

  3. Fast neutron mutants database and web displays at SoyBase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    SoyBase, the USDA-ARS soybean genetics and genomics database, has been expanded to include data for the fast neutron mutants produced by Bolon, Vance, et al. In addition to the expected text and sequence homology searches and visualization of the indels in the context of the genome sequence viewer, ...

  4. Surface modification of polypropylene based particle foams

    NASA Astrophysics Data System (ADS)

    Schreier, P.; Trassl, C.; Altstädt, V.

    2014-05-01

    This paper deals with the modification of the surface properties of expanded polypropylene (EPP). EPP is a semi-hard to soft elastic thermoplastic foam. The characteristic surface of EPP shows process-related steam nozzle imprints and gussets. Therefore EPP does not satisfy the quality requirements for visible automotive applications. In order to meet these demands, plastic surfaces are usually enhanced with functional or decorative coatings, e.g. textiles, plastic films or paint. The coating of plastics with low surface energies such as PP often leads to adhesion problems by reason of the missing polar and functional groups. This paper gives an evaluation of activation and pre-treatment methods of EPP, with the aim to identify the most suitable pre-treatment method. For this purpose five typical surface treatment methods - flame treatment, corona, fluorination, atmospheric and low-pressure plasma - were performed on EPP samples. As a comparison criterion the maximum increase in the adhesion force between a polyurethane-based coating and the modified EPP substrate was selected. Moreover the influence of the selected pre-treatment method on the increase in the total surface energy and its polar component was investigated by the drop shape analysis method. The results showed that the contact angle measurement is a suitable method to determine the polar and disperse fractions of the surface tension of EPP. Furthermore, all performed methods increased the adhesion of EPP.

  5. Intra-patient colon surface registration based on teniae; coli

    NASA Astrophysics Data System (ADS)

    Lamy, Julien; Summers, Ronald M.

    2007-03-01

    CT colonography, a prevalent tool to diagnose colon cancer in its early stages, is often limited by bad distention, or retained fluids, which will cause segments of the colon to be impossible to process by CAD tools. By scanning patients in both prone and supine positions, collapsed segments and retained fluids will not be in the same place in both images, increasing the length of the colon that can be processed correctly. In order to fully use these two scans, they must be registered, so that a lesion identified on one of them can be mapped to the other, thus increasing sensitivity and specificity of CAD tools. The surface of the colon is however large (more than half a million vertices on our images), and has no canonical shape, which makes atlases and other widely used registration algorithms non optimal. We present in this paper a fast method to register the colon surface between prone and supine scans using landmarks present on the colon, the teniae coli. Our method is composed of three steps. First, we register the body, based on manually placed landmarks. Then we register the three teniae; coli, and, from this registration, we compute a deformation field for each vertex of the colon surface. We tested our method on 5 cases, by measuring the RMS error after body registration, quantifying the intrisic movement of the colon, and after colon surface registration. The RMS error was reduced from 1.8 cm to 0.49 cm, a reduction of 71%.

  6. Fast switchable grating based on orthogonal photo alignments of ferroelectric liquid crystals

    NASA Astrophysics Data System (ADS)

    Srivastava, A. K.; Hu, Wei; Chigrinov, V. G.; Kiselev, A. D.; Lu, Yan-Qing

    2012-07-01

    We demonstrate a fast switchable grating based on ferroelectric liquid crystals and orthogonal planar alignment by means of photo alignments. Both 1D and 2D gratings have been constructed. The proposed diffracting element provides fast response time of around 20 μs, contrast of 7000:1 and high diffraction efficiency, at the electric field of 6 V/μm. The saturated electro-optical (EO) states up to very high frequency (≈5 kHz) are the real advantage of the proposed switchable grating, which opens several opportunities to improve the quality of existing devices and to find new applications.

  7. Tunable temporal gap based on simultaneous fast and slow light in electro-optic photonic crystals.

    PubMed

    Li, Guangzhen; Chen, Yuping; Jiang, Haowei; Liu, Yi'an; Liu, Xiao; Chen, Xianfeng

    2015-07-13

    We demonstrated a tunable temporal gap based on simultaneous fast and slow light in electro-optic photonic crystals. The light experiences an anomalous dispersion near the transmission center and a normal dispersion away from the center, where it can be accelerated and slowed down, respectively. We also obtained the switch between fast and slow light by adjusting the external electric filed. The observed largest temporal gap is 541 ps, which is crucial in practical event operation inside the gap. The results offer a new solution for temporal cloak.

  8. Fast polarization-state tracking scheme based on radius-directed linear Kalman filter.

    PubMed

    Yang, Yanfu; Cao, Guoliang; Zhong, Kangping; Zhou, Xian; Yao, Yong; Lau, Alan Pak Tao; Lu, Chao

    2015-07-27

    We propose and experimentally demonstrate a fast polarization tracking scheme based on radius-directed linear Kalman filter. It has the advantages of fast convergence and is inherently insensitive to phase noise and frequency offset effects. The scheme is experimentally compared to conventional polarization tracking methods on the polarization rotation angular frequency. The results show that better tracking capability with more than one order of magnitude improvement is obtained in the cases of polarization multiplexed QPSK and 16QAM signals. The influences of the filter tuning parameters on tracking performance are also investigated in detail.

  9. Ultra Fast X-ray Streak Camera for TIM Based Platforms

    SciTech Connect

    Marley, E; Shepherd, R; Fulkerson, E S; James, L; Emig, J; Norman, D

    2012-05-02

    Ultra fast x-ray streak cameras are a staple for time resolved x-ray measurements. There is a need for a ten inch manipulator (TIM) based streak camera that can be fielded in a newer large scale laser facility. The LLNL ultra fast streak camera's drive electronics have been upgraded and redesigned to fit inside a TIM tube. The camera also has a new user interface that allows for remote control and data acquisition. The system has been outfitted with a new sensor package that gives the user more operational awareness and control.

  10. Photonic-chip-based tunable slow and fast light via stimulated Brillouin scattering.

    PubMed

    Pant, Ravi; Byrnes, Adam; Poulton, Christopher G; Li, Enbang; Choi, Duk-Yong; Madden, Steve; Luther-Davies, Barry; Eggleton, Benjamin J

    2012-03-01

    We report the first (to our knowledge) demonstration of photonic chip based tunable slow and fast light via stimulated Brillouin scattering. Slow, fast, and negative group velocities were observed in a 7 cm long chalcogenide (As(2)S(3)) rib waveguide with a group index change ranging from ~-44 to +130, which results in a maximum delay of ~23 ns at a relatively low gain of ~23 dB. Demonstration of large tunable delays in a chip scale device opens up applications such as frequency sensing and true-time delay for a phased array antenna, where integration and delays ~10 ns are highly desirable.

  11. Fast online Monte Carlo-based IMRT planning for the MRI linear accelerator

    NASA Astrophysics Data System (ADS)

    Bol, G. H.; Hissoiny, S.; Lagendijk, J. J. W.; Raaymakers, B. W.

    2012-03-01

    The MRI accelerator, a combination of a 6 MV linear accelerator with a 1.5 T MRI, facilitates continuous patient anatomy updates regarding translations, rotations and deformations of targets and organs at risk. Accounting for these demands high speed, online intensity-modulated radiotherapy (IMRT) re-optimization. In this paper, a fast IMRT optimization system is described which combines a GPU-based Monte Carlo dose calculation engine for online beamlet generation and a fast inverse dose optimization algorithm. Tightly conformal IMRT plans are generated for four phantom cases and two clinical cases (cervix and kidney) in the presence of the magnetic fields of 0 and 1.5 T. We show that for the presented cases the beamlet generation and optimization routines are fast enough for online IMRT planning. Furthermore, there is no influence of the magnetic field on plan quality and complexity, and equal optimization constraints at 0 and 1.5 T lead to almost identical dose distributions.

  12. Fast in-situ tool inspection based on inverse fringe projection and compact sensor heads

    NASA Astrophysics Data System (ADS)

    Matthias, Steffen; Kästner, Markus; Reithmeier, Eduard

    2016-11-01

    Inspection of machine elements is an important task in production processes in order to ensure the quality of produced parts and to gather feedback for the continuous improvement process. A new measuring system is presented, which is capable of performing the inspection of critical tool geometries, such as gearing elements, inside the forming machine. To meet the constraints on sensor head size and inspection time imposed by the limited space inside the machine and the cycle time of the process, the measuring device employs a combination of endoscopy techniques with the fringe projection principle. Compact gradient index lenses enable a compact design of the sensor head, which is connected to a CMOS camera and a flexible micro-mirror based projector via flexible fiber bundles. Using common fringe projection patterns, the system achieves measuring times of less than five seconds. To further reduce the time required for inspection, the generation of inverse fringe projection patterns has been implemented for the system. Inverse fringe projection speeds up the inspection process by employing object-adapted patterns, which enable the detection of geometry deviations in a single image. Two different approaches to generate object adapted patterns are presented. The first approach uses a reference measurement of a manufactured tool master to generate the inverse pattern. The second approach is based on a virtual master geometry in the form of a CAD file and a ray-tracing model of the measuring system. Virtual modeling of the measuring device and inspection setup allows for geometric tolerancing for free-form surfaces by the tool designer in the CAD-file. A new approach is presented, which uses virtual tolerance specifications and additional simulation steps to enable fast checking of metric tolerances. Following the description of the pattern generation process, the image processing steps required for inspection are demonstrated on captures of gearing geometries.

  13. Invariant Fast Diffusion on the Surfaces of Ultrastable and Aged Molecular Glasses.

    PubMed

    Zhang, Yue; Fakhraai, Zahra

    2017-02-10

    Surface diffusion of molecular glasses is found to be orders of magnitude faster than bulk diffusion, with a stronger dependence on the molecular size and intermolecular interactions. In this study, we investigate the effect of variations in bulk dynamics on the surface diffusion of molecular glasses. Using the tobacco mosaic virus as a probe particle, we measure the surface diffusion on glasses of the same composition but with orders of magnitude of variations in bulk relaxation dynamics, produced by physical vapor deposition, physical aging, and liquid quenching. The bulk fictive temperatures of these glasses span over 35 K, indicating 13 to 20 orders of magnitude changes in bulk relaxation times. However, the surface diffusion coefficients on these glasses are measured to be identical at two temperatures below the bulk glass transition temperature T_{g}. These results suggest that surface diffusion has no dependence on the bulk relaxation dynamics when measured below T_{g}.

  14. Invariant Fast Diffusion on the Surfaces of Ultrastable and Aged Molecular Glasses

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Fakhraai, Zahra

    2017-02-01

    Surface diffusion of molecular glasses is found to be orders of magnitude faster than bulk diffusion, with a stronger dependence on the molecular size and intermolecular interactions. In this study, we investigate the effect of variations in bulk dynamics on the surface diffusion of molecular glasses. Using the tobacco mosaic virus as a probe particle, we measure the surface diffusion on glasses of the same composition but with orders of magnitude of variations in bulk relaxation dynamics, produced by physical vapor deposition, physical aging, and liquid quenching. The bulk fictive temperatures of these glasses span over 35 K, indicating 13 to 20 orders of magnitude changes in bulk relaxation times. However, the surface diffusion coefficients on these glasses are measured to be identical at two temperatures below the bulk glass transition temperature Tg . These results suggest that surface diffusion has no dependence on the bulk relaxation dynamics when measured below Tg.

  15. Fast numerical method for electromagnetic scattering from an object above a large-scale layered rough surface at large incident angle: vertical polarization.

    PubMed

    Wang, A-Q; Guo, L-X; Chai, C

    2011-02-01

    A fast numerical method has been proposed in this paper for calculating the electromagnetic scattering from a perfectly electric conducting object above a two-layered dielectric rough surface. The focus in this study is large incidence. The parallel fast multipole method is combined with the method of moments for fast implementation of the scattering from this composite model. The biconjugate gradient method is adopted to solve the unsymmetrical matrix equation and parallelized. The simulating time and parallel speedup ratio with different processors are provided. Several numerical results are shown and analyzed to discuss the influences of the parameters of the rough surface, the object, and the intermediate medium on the bistatic scattering.

  16. Case-based reasoning(CBR) model for ultra-fast cooling in plate mill

    NASA Astrophysics Data System (ADS)

    Hu, Xiao; Wang, Zhaodong; Wang, Guodong

    2014-11-01

    New generation thermo-mechanical control process(TMCP) based on ultra-fast cooling is being widely adopted in plate mill to product high-performance steel material at low cost. Ultra-fast cooling system is complex because of optimizing the temperature control error generated by heat transfer mathematical model and process parameters. In order to simplify the system and improve the temperature control precision in ultra-fast cooling process, several existing models of case-based reasoning(CBR) model are reviewed. Combining with ultra-fast cooling process, a developed R5 CBR model is proposed, which mainly improves the case representation, similarity relation and retrieval module. Certainty factor is defined in semantics memory unit of plate case which provides not only internal data reliability but also product performance reliability. Similarity relation is improved by defined power index similarity membership function. Retrieval process is simplified and retrieval efficiency is improved apparently by windmill retrieval algorithm. The proposed CBR model is used for predicting the case of cooling strategy and its capability is superior to traditional process model. In order to perform comprehensive investigations on ultra-fast cooling process, different steel plates are considered for the experiment. The validation experiment and industrial production of proposed CBR model are carried out, which demonstrated that finish cooling temperature(FCT) error is controlled within ±25°C and quality rate of product is more than 97%. The proposed CBR model can simplify ultra-fast cooling system and give quality performance for steel product.

  17. Implementation of a fast analytic ground state potential energy surface for the N({sup 2}D)+H{sub 2} reaction.

    SciTech Connect

    Ho, T.-S.; Rabitz, H.; Aoiz, F. J.; Banares, L.; Vazquez, S. A.; Harding, L. B.; Chemistry; Princeton Univ.; Univ. Complutense

    2003-08-08

    A new implementation is presented for the potential energy surface (PES) of the 1{sup 2}A' state of the N({sup 2}D)+H{sub 2} system based on a set of 2715 ab initio points resulting from the multireference configuration interaction (MRCI) calculations. The implementation is carried out using the reproducing Kernel Hilbert Space interpolation method. Range parameters, via bond-order-like coordinates, are properly chosen to render a sufficiently short-range three-body interaction and a regularization procedure is invoked to yield a globally smooth PES. A fast algorithm, with the help of low-order spline reproducing kernels, is implemented for the computation of the PES and, particularly, its gradients, whose fast evaluation is essential for large scale quasi-classical trajectory calculations. It is found that the new PES can be evaluated more than ten times faster than that of an existing (old) PES based on a smaller number (1141) of data points resulting from the same MRCI calculations and a similar interpolation procedure. Although there is a general good correspondence between the two surfaces, the new PES is in much better agreement with the ab initio calculations, especially in key stationary point regions including the C{sub 2v} minimum, the C{sub 2v} transition state, and the N-H-H linear barrier. Moreover, the new PES is free of spurious small scale features. Analytic gradients are made available in the new PES code to further facilitate quasiclassical trajectory calculations, which have been performed and compared with the results based on the old surface.

  18. Competing descriptions of diffusion profiles with two features: Surface space-charge layer versus fast grain-boundary diffusion

    NASA Astrophysics Data System (ADS)

    Schraknepper, H.; De Souza, R. A.

    2016-02-01

    Two different physical processes, (i) fast grain-boundary diffusion (FGBD) of oxygen and (ii) hindered oxygen diffusion in a surface space-charge layer, yield oxygen isotope diffusion profiles in a similar form. Two features are observed, with the short, sharp profile close to the surface being followed by a longer, shallower profile. In this study, we develop a procedure for deciding which of the two descriptions applies to experimentally measured profiles. Specifically, we solve Fick's second law, using finite-element simulations, to obtain oxygen isotope diffusion profiles for the two cases. Each set of profiles is then analysed in terms of the competing description. In this manner, we derive falsifiable conditions that allow physical processes to be assigned unambiguously to the two features of such isotope profiles. Applying these conditions to experimental profiles for SrTiO3 single crystals published in the literature, we find that FGBD is an invalid model for describing the diffusion processes.

  19. Supra-additive contribution of shape and surface information to individual face discrimination as revealed by fast periodic visual stimulation.

    PubMed

    Dzhelyova, Milena; Rossion, Bruno

    2014-12-24

    Face perception depends on two main sources of information--shape and surface cues. Behavioral studies suggest that both of them contribute roughly equally to discrimination of individual faces, with only a small advantage provided by their combination. However, it is difficult to quantify the respective contribution of each source of information to the visual representation of individual faces with explicit behavioral measures. To address this issue, facial morphs were created that varied in shape only, surface only, or both. Electrocephalogram (EEG) were recorded from 10 participants during visual stimulation at a fast periodic rate, in which the same face was presented four times consecutively and the fifth face (the oddball) varied along one of the morphed dimensions. Individual face discrimination was indexed by the periodic EEG response at the oddball rate (e.g., 5.88 Hz/5 = 1.18 Hz). While shape information was discriminated mainly at right occipitotemporal electrode sites, surface information was coded more bilaterally and provided a larger response overall. Most importantly, shape and surface changes alone were associated with much weaker responses than when both sources of information were combined in the stimulus, revealing a supra-additive effect. These observations suggest that the two kinds of information combine nonlinearly to provide a full individual face representation, face identity being more than the sum of the contribution of shape and surface cues.

  20. Fast computer simulation of reconstructed image from rainbow hologram based on GPU

    NASA Astrophysics Data System (ADS)

    Shuming, Jiao; Yoshikawa, Hiroshi

    2015-10-01

    A fast computer simulation solution for rainbow hologram reconstruction based on GPU is proposed. In the commonly used segment Fourier transform method for rainbow hologram reconstruction, the computation of 2D Fourier transform on each hologram segment is very time consuming. GPU-based parallel computing can be applied to improve the computing speed. Compared with CPU computing, simulation results indicate that our proposed GPU computing can effectively reduce the computation time by as much as eight times.

  1. A surface-based cloud observing system

    NASA Technical Reports Server (NTRS)

    Albrecht, B. A.; Ackerman, T. P.; Thomson, D. W.; Mace, G.; Miller, M. A.; Peters, R. M.

    1991-01-01

    The paper describes a surface-based system, called the Cloud Observing System (COS), that was developed for measurements of the dynamical and thermodynamical properties of clouds and of their interaction with the large-scale environment, by combining several remote sensors and in situ systems. The atmospheric parameters that will be measured by COS include precipitation, the velocity and direction of wind, the cloud liquid water, the low-level winds and turbulence structure, integrated liquid and vapor quantities, the temperature and water profiles, the cloud radiance and the cloud base temperature, irradiances at the surface, the low-level temperature profile, the cloud-base height, and the cloud fraction; video cameras will provide visual records of clouds.

  2. Fast and Simple Preparation of Patterned Surfaces with Hydrophilic Polymer Brushes by Micromolding in Capillaries.

    PubMed

    Vonhören, Benjamin; Langer, Marcel; Abt, Doris; Barner-Kowollik, Christopher; Ravoo, Bart Jan

    2015-12-22

    Micropatterns of hydrophilic polymer brushes were prepared by micromolding in capillaries (MIMIC). The polymers are covalently bound to the surfaces by a rapid hetero Diels-Alder reaction, constituting the first example of polymers grafted to surfaces in a defined pattern by MIMIC. The polymers [poly(acrylic acid), poly(hydroxyethyl acrylate), and poly(tetraethylene glycol acrylate) ranging in molecular weight from 1500 to 6000 g mol(-1)] were prepared with narrow dispersities via the reversible addition-fragmentation chain transfer (RAFT) process using a highly electron deficient RAFT agent that can react with surface-anchored dienes such as cyclopentadiene. We demonstrate that the anchoring method is facile to perform and highly suitable for preparing patterned surfaces that are passivated against biological impact in well-defined areas.

  3. Fast robust non-sequential optical ray-tracing with implicit algebraic surfaces

    NASA Astrophysics Data System (ADS)

    Greynolds, Alan W.

    2015-09-01

    The fastest, most robust, general technique for non-sequentially ray-tracing a large class of imaging and non-imaging optical systems is by geometric modeling with algebraic (i.e. polynomial) implicit surfaces. The basic theory of these surfaces with special attention to optimizing their precise intersection with a ray (even at grazing incidence) is outlined for an admittedly limited software implementation. On a couple of "tame" examples, a 64-bit Windows 7 version is significantly faster than the fastest commercial design software (all multi-threaded). Non-sequential ray-surface interactions approaching 30M/sec are achieved on a 12-core 2.67 GHz Mac Pro desktop computer. For a more exotic example of a 6th degree Wood's horn beam dump (light trap), a 32-bit Windows single thread version traces rays nearly 4 times faster than the commercial ASAP software's implicit algebraic surface and over 13 times faster than its equivalent NURBS surface. However, implicit surfaces are foreign to most CAD systems and thus unfortunately, don't easily fit into a modern workflow.

  4. Fast and slow deposition of silver nanorods on planar surfaces: application to metal-enhanced fluorescence.

    PubMed

    Aslan, Kadir; Leonenko, Zoya; Lakowicz, Joseph R; Geddes, Chris D

    2005-03-03

    Two methods have been considered for the deposition of silver nanorods onto conventional glass substrates. In the first method, silver nanorods were deposited onto 3-(aminopropyl)triethoxysilane-coated glass substrates simply by immersing the substrates into the silver nanorod solution. In the second method, spherical silver seeds that were chemically attached to the surface were subsequently converted and grown into silver nanorods in the presence of a cationic surfactant and silver ions. The size of the silver nanorods was controlled by sequential immersion of silver seed-coated glass substrates into a growth solution and by the duration of immersion, ranging from tens of nanometers to a few micrometers. Atomic force microscopy and optical density measurements were used to characterize the silver nanorods deposited onto the surface of the glass substrates. The application of these new surfaces is for metal-enhanced fluorescence (MEF), whereby the close proximity of silver nanostructures can alter the radiative decay rate of fluorophores, producing enhanced signal intensities and an increased fluorophore photostability. In this paper, it is indeed shown that irregularly shaped silver nanorod-coated surfaces are much better MEF surfaces as compared to traditional silver island or colloid films. Subsequently, these new silver nanorod preparation procedures are likely to find a common place in MEF, as they are a quicker and much cheaper alternative as compared to surfaces fabricated by traditional nanolithographic techniques.

  5. Fast and automatic depth control of iterative bone ablation based on optical coherence tomography data

    NASA Astrophysics Data System (ADS)

    Fuchs, Alexander; Pengel, Steffen; Bergmeier, Jan; Kahrs, Lüder A.; Ortmaier, Tobias

    2015-07-01

    Laser surgery is an established clinical procedure in dental applications, soft tissue ablation, and ophthalmology. The presented experimental set-up for closed-loop control of laser bone ablation addresses a feedback system and enables safe ablation towards anatomical structures that usually would have high risk of damage. This study is based on combined working volumes of optical coherence tomography (OCT) and Er:YAG cutting laser. High level of automation in fast image data processing and tissue treatment enables reproducible results and shortens the time in the operating room. For registration of the two coordinate systems a cross-like incision is ablated with the Er:YAG laser and segmented with OCT in three distances. The resulting Er:YAG coordinate system is reconstructed. A parameter list defines multiple sets of laser parameters including discrete and specific ablation rates as ablation model. The control algorithm uses this model to plan corrective laser paths for each set of laser parameters and dynamically adapts the distance of the laser focus. With this iterative control cycle consisting of image processing, path planning, ablation, and moistening of tissue the target geometry and desired depth are approximated until no further corrective laser paths can be set. The achieved depth stays within the tolerances of the parameter set with the smallest ablation rate. Specimen trials with fresh porcine bone have been conducted to prove the functionality of the developed concept. Flat bottom surfaces and sharp edges of the outline without visual signs of thermal damage verify the feasibility of automated, OCT controlled laser bone ablation with minimal process time.

  6. An OSEE Based Portable Surface Contamination Monitor

    NASA Technical Reports Server (NTRS)

    Perey, Daniel F.

    1997-01-01

    Many industrial and aerospace processes involving the joining of materials, require sufficient surface cleanliness to insure proper bonding. Processes as diverse as painting, welding, or the soldering of electronic circuits will be compromised if prior inspection and removal of surface contaminants is inadequate. As process requirements become more stringent and the number of different materials and identified contaminants increases, various instruments and techniques have been developed for improved inspection. One such technique based on the principle of Optically Stimulated Electron Emission (OSEE) has been explored for a number of years as a tool for surface contamination monitoring. Some of the benefits of OSEE are: it's non-contacting; requires little operator training; and has very high contamination sensitivity. This paper describes the development of a portable OSEE based surface contamination monitor. The instrument is suitable for both hand-held and robotic inspections with either manual or automated control of instrument operation. In addition, instrument output data is visually displayed to the operator and may be output to an external computer for archiving or analysis.

  7. Monitoring Surface Deformation using Polarimetric Ground Based Interferometric Radar

    NASA Astrophysics Data System (ADS)

    Legarsky, J. J.; Gomez, F.; Rosenblad, B.; Loehr, E.; Cherukumilli, S.; Deng, H.; Held, B.; Jenkins, W.

    2012-12-01

    Surface deformation monitoring using ground based interferometric radar (GBIR) measurements may be desirable for a number of applications in the earth sciences. The University of Missouri (MU) research team has ongoing efforts to use the MU GBIR for monitoring surface deformation at a number of sites. Measurements have been collected at sites requiring access by various transportation means such as using off-road vehicle, hiking, and helicopter. Once on site, initial setup takes about 10 minutes. After setup, an image may be acquired by azimuth scan about every 20 seconds. The highly portable system lends itself to rapid deployment in remote environments and repeat survey sites. The MU GBIR's high portability and fast imaging capabilities allow rapid surveying and long-term surveying potential of surface deformation. Imagery may be formed in near real time for initial quick looks. After data collection, imagery data may be further enhanced by radiometric calibration, polarimetric calibration, and time-series analysis. Imaging may be acquired at the electromagnetic spectral bands of C-band and Ku-band. Prior demonstration of millimeter and better sensitivity to deformation over the course of a day of data collects has been performed using the MU GBIR. In addition, the MU GBIR can be removed and re-positioned at the same point with geodetic-grade precision for repeat surveys. Study results and additional development progress will be presented. This project is sponsored by a grant from the National Science Foundation.

  8. Progressive FastICA Peel-Off and Convolution Kernel Compensation Demonstrate High Agreement for High Density Surface EMG Decomposition

    PubMed Central

    Chen, Maoqi

    2016-01-01

    Decomposition of electromyograms (EMG) is a key approach to investigating motor unit plasticity. Various signal processing techniques have been developed for high density surface EMG decomposition, among which the convolution kernel compensation (CKC) has achieved high decomposition yield with extensive validation. Very recently, a progressive FastICA peel-off (PFP) framework has also been developed for high density surface EMG decomposition. In this study, the CKC and PFP methods were independently applied to decompose the same sets of high density surface EMG signals. Across 91 trials of 64-channel surface EMG signals recorded from the first dorsal interosseous (FDI) muscle of 9 neurologically intact subjects, there were a total of 1477 motor units identified from the two methods, including 969 common motor units. On average, 10.6 ± 4.3 common motor units were identified from each trial, which showed a very high matching rate of 97.85 ± 1.85% in their discharge instants. The high degree of agreement of common motor units from the CKC and the PFP processing provides supportive evidence of the decomposition accuracy for both methods. The different motor units obtained from each method also suggest that combination of the two methods may have the potential to further increase the decomposition yield. PMID:27642525

  9. A Universal Fast Algorithm for Sensitivity-Based Structural Damage Detection

    PubMed Central

    Yang, Q. W.; Liu, J. K.; Li, C. H.; Liang, C. F.

    2013-01-01

    Structural damage detection using measured response data has emerged as a new research area in civil, mechanical, and aerospace engineering communities in recent years. In this paper, a universal fast algorithm is presented for sensitivity-based structural damage detection, which can quickly improve the calculation accuracy of the existing sensitivity-based technique without any high-order sensitivity analysis or multi-iterations. The key formula of the universal fast algorithm is derived from the stiffness and flexibility matrix spectral decomposition theory. With the introduction of the key formula, the proposed method is able to quickly achieve more accurate results than that obtained by the original sensitivity-based methods, regardless of whether the damage is small or large. Three examples are used to demonstrate the feasibility and superiority of the proposed method. It has been shown that the universal fast algorithm is simple to implement and quickly gains higher accuracy over the existing sensitivity-based damage detection methods. PMID:24453815

  10. CerioFAST{trademark}: An acute toxicity test based on Ceriodaphnia dubia feeding behavior

    SciTech Connect

    Bitton, G.; Rhodes, K.; Koopman, B.

    1996-02-01

    The authors have developed a rapid acute toxicity test (CerioFAST{trademark}) based on suppression of feeding activity of Ceriodaphnia dubia in the presence of toxicants. The bioassay consists of a 1-h exposure period to a given toxicant. Yeast cells, stained with a fluorescent dye, are added 20 min before the end of the exposure period. Response to a toxic sample is indicated by the absence of fluorescence in the gut of the daphnids. CerioFAST was compared to the standard 48-h C. dubia acute bioassay, using heavy metals and organic compounds.CerioFAST EC50s of Cd, Cu, Pb, Ag, Zn, and carbofuran were in the 0.01--0.1-mg/L range, whereas EC50s of hexachloroethane, pentachlorophenol, trichlorophenol, and lindane were in the 1--10-mg/L range. CerioFAST EC50s of the heavy metals and organics were well correlated with Ec50s obtained with the 48-h C. dubia bioassay.

  11. Arikan and Alamouti matrices based on fast block-wise inverse Jacket transform

    NASA Astrophysics Data System (ADS)

    Lee, Moon Ho; Khan, Md Hashem Ali; Kim, Kyeong Jin

    2013-12-01

    Recently, Lee and Hou (IEEE Signal Process Lett 13: 461-464, 2006) proposed one-dimensional and two-dimensional fast algorithms for block-wise inverse Jacket transforms (BIJTs). Their BIJTs are not real inverse Jacket transforms from mathematical point of view because their inverses do not satisfy the usual condition, i.e., the multiplication of a matrix with its inverse matrix is not equal to the identity matrix. Therefore, we mathematically propose a fast block-wise inverse Jacket transform of orders N = 2 k , 3 k , 5 k , and 6 k , where k is a positive integer. Based on the Kronecker product of the successive lower order Jacket matrices and the basis matrix, the fast algorithms for realizing these transforms are obtained. Due to the simple inverse and fast algorithms of Arikan polar binary and Alamouti multiple-input multiple-output (MIMO) non-binary matrices, which are obtained from BIJTs, they can be applied in areas such as 3GPP physical layer for ultra mobile broadband permutation matrices design, first-order q-ary Reed-Muller code design, diagonal channel design, diagonal subchannel decompose for interference alignment, and 4G MIMO long-term evolution Alamouti precoding design.

  12. Assessing cognitive processes with diffusion model analyses: a tutorial based on fast-dm-30

    PubMed Central

    Voss, Andreas; Voss, Jochen; Lerche, Veronika

    2015-01-01

    Diffusion models can be used to infer cognitive processes involved in fast binary decision tasks. The model assumes that information is accumulated continuously until one of two thresholds is hit. In the analysis, response time distributions from numerous trials of the decision task are used to estimate a set of parameters mapping distinct cognitive processes. In recent years, diffusion model analyses have become more and more popular in different fields of psychology. This increased popularity is based on the recent development of several software solutions for the parameter estimation. Although these programs make the application of the model relatively easy, there is a shortage of knowledge about different steps of a state-of-the-art diffusion model study. In this paper, we give a concise tutorial on diffusion modeling, and we present fast-dm-30, a thoroughly revised and extended version of the fast-dm software (Voss and Voss, 2007) for diffusion model data analysis. The most important improvement of the fast-dm version is the possibility to choose between different optimization criteria (i.e., Maximum Likelihood, Chi-Square, and Kolmogorov-Smirnov), which differ in applicability for different data sets. PMID:25870575

  13. Study of wave-particle interaction between fast Magnetosonic and energetic electrons based on numerical simulation

    NASA Astrophysics Data System (ADS)

    Fu, S.

    2015-12-01

    There are many energetic electrons in the radiation belt of Earth. When the geomagnetic activity becomes stronger, the energy flux of energetic electrons will increase to more than ten times in the outer radiation belt, therefore it is very important to study how the energetic electrons generate and the lifetime of energetic electrons for space weather research. The acceleration of electrons in radiation belt is mainly depending on wave-particle interaction: the whistler mode chorus is the main driver for local acceleration mechanism, which could accelerate and loss energetic electrons; the geomagnetic pulsation ULF wave will cause energetic electron inward radial diffusion which will charge the electrons; recently observation results show us that the fast magnetosonic waves may also accelerate energetic electrons. For the reason that we try to study the wave-particle interaction between fast Magnetosonic and energetic electrons based on numerical simulation, in which the most important past is at the storm time the combination of highly warped Earth magnetic field and fast magnetosonic wave field will be applied for the electromagnetic environment of moving test particles. The energy, pitch angle and cross diffusion coefficients will be calculated respectively in this simulation to study how the electrons receive energy from fast magnetosonic wave. The diffusion coefficients within different dipole Earth magnetic field and non-dipole storm magnetic field are compared, while dynamics of electrons at selected initial energys are shown in our study.

  14. Polylactide-based polyurethane shape memory nanocomposites (Fe3O4/PLAUs) with fast magnetic responsiveness

    NASA Astrophysics Data System (ADS)

    Gu, Shu-Ying; Jin, Sheng-Peng; Gao, Xie-Feng; Mu, Jian

    2016-05-01

    Polylactide-based polyurethane shape memory nanocomposites (Fe3O4/PLAUs) with fast magnetic responsiveness are presented. For the purpose of fast response and homogeneous dispersion of magnetic nanoparticles, oleic acid was used to improve the dispersibility of Fe3O4 nanoparticles in a polymer matrix. A homogeneous distribution of Fe3O4 nanoparticles in the polymer matrix was obtained for nanocomposites with low Fe3O4 loading content. A small agglomeration was observed for nanocomposites with 6 wt% and 9 wt% loading content, leading to a small decline in the mechanical properties. PLAU and its nanocomposites have glass transition around 52 °C, which can be used as the triggering temperature. PLAU and its nanocomposites have shape fixity ratios above 99%, shape recovery ratios above 82% for the first cycle and shape recovery ratios above 91% for the second cycle. PLAU and its nanocomposites also exhibit a fast water bath or magnetic responsiveness. The magnetic recovery time decreases with an increase in the loading content of Fe3O4 nanoparticles due to an improvement in heating performance for increased weight percentage of fillers. The nanocomposites have fast responses in an alternating magnetic field and have potential application in biomedical areas such as intravascular stent.

  15. FPS-RAM: Fast Prefix Search RAM-Based Hardware for Forwarding Engine

    NASA Astrophysics Data System (ADS)

    Zaitsu, Kazuya; Yamamoto, Koji; Kuroda, Yasuto; Inoue, Kazunari; Ata, Shingo; Oka, Ikuo

    Ternary content addressable memory (TCAM) is becoming very popular for designing high-throughput forwarding engines on routers. However, TCAM has potential problems in terms of hardware and power costs, which limits its ability to deploy large amounts of capacity in IP routers. In this paper, we propose new hardware architecture for fast forwarding engines, called fast prefix search RAM-based hardware (FPS-RAM). We designed FPS-RAM hardware with the intent of maintaining the same search performance and physical user interface as TCAM because our objective is to replace the TCAM in the market. Our RAM-based hardware architecture is completely different from that of TCAM and has dramatically reduced the costs and power consumption to 62% and 52%, respectively. We implemented FPS-RAM on an FPGA to examine its lookup operation.

  16. Fast implementation of sparse iterative covariance-based estimation for source localization.

    PubMed

    Zhang, Qilin; Abeida, Habti; Xue, Ming; Rowe, William; Li, Jian

    2012-02-01

    Fast implementations of the sparse iterative covariance-based estimation (SPICE) algorithm are presented for source localization with a uniform linear array (ULA). SPICE is a robust, user parameter-free, high-resolution, iterative, and globally convergent estimation algorithm for array processing. SPICE offers superior resolution and lower sidelobe levels for source localization compared to the conventional delay-and-sum beamforming method; however, a traditional SPICE implementation has a higher computational complexity (which is exacerbated in higher dimensional data). It is shown that the computational complexity of the SPICE algorithm can be mitigated by exploiting the Toeplitz structure of the array output covariance matrix using Gohberg-Semencul factorization. The SPICE algorithm is also extended to the acoustic vector-sensor ULA scenario with a specific nonuniform white noise assumption, and the fast implementation is developed based on the block Toeplitz properties of the array output covariance matrix. Finally, numerical simulations illustrate the computational gains of the proposed methods.

  17. Microwave-accelerated surface plasmon-coupled directional luminescence 2: a platform technology for ultra fast and sensitive target DNA detection in whole blood.

    PubMed

    Aslan, Kadir; Previte, Michael J R; Zhang, Yongxia; Geddes, Chris D

    2008-02-29

    The application of Microwave-Accelerated Surface Plasmon-Coupled Luminescence (MA-SPCL) to fast and sensitive DNA hybridization assays in buffer and whole blood is presented. In this regard, a model DNA hybridization assay whereby a fluorophore-labeled target ssDNA specific to human immunodeficiency, Hepatitis C (Hep C), is probed by an anchor probe immobilized on thin gold films, is driven to completion within 1 min with microwave heating, as compared to an identical assay completed in approximately 4 h at room temperature. Finite-Difference Time-Domain calculations show that gold disks are preferentially heated around the edges creating a temperature gradient along the disks, which in turn results in the larger influx of complementary DNA towards anchor probe-modified surface. Thermal images of the assay platform during microwave heating also provide additional information on the microwave heating pattern in the microwave cavity. Finally, the effects of low power microwave heating on the ability of DNA to re-hybridize with the complimentary target on the surface gold films, which allows the multiple re-use of the gold films, is demonstrated. The MA-SPCL technique offers an alternative approach to current DNA based detection technologies, especially when speed and sensitivity are required, such as in the identification of DNA or even RNA-based diseases using whole blood samples that affect human health.

  18. Fast Spectral Collocation Method for Surface Integral Equations of Potential Problems in a Spheroid

    PubMed Central

    Xu, Zhenli; Cai, Wei

    2009-01-01

    This paper proposes a new technique to speed up the computation of the matrix of spectral collocation discretizations of surface single and double layer operators over a spheroid. The layer densities are approximated by a spectral expansion of spherical harmonics and the spectral collocation method is then used to solve surface integral equations of potential problems in a spheroid. With the proposed technique, the computation cost of collocation matrix entries is reduced from 𝒪(M2N4) to 𝒪(MN4), where N2 is the number of spherical harmonics (i.e., size of the matrix) and M is the number of one-dimensional integration quadrature points. Numerical results demonstrate the spectral accuracy of the method. PMID:20414359

  19. Performance study of the fast timing Cherenkov detector based on a microchannel plate PMT

    NASA Astrophysics Data System (ADS)

    Finogeev, D. A.; Grigoriev, V. A.; Kaplin, V. A.; Karavichev, O. V.; Karavicheva, T. L.; Konevskikh, A. S.; Kurepin, A. B.; Kurepin, A. N.; Loginov, V. A.; Mayevskaya, A. I.; Melikyan, Yu A.; Morozov, I. V.; Serebryakov, D. V.; Shabanov, A. I.; Slupecki, M.; Tikhonov, A. A.; Trzaska, W. H.

    2017-01-01

    Prototype of the fast timing Cherenkov detector, applicable in high-energy collider experiments, has been developed basing on the modified Planacon XP85012 MCP-PMT and fused silica radiators. We present the reasons and description of the MCP-PMT modification, timing and amplitude characteristics of the prototype including the summary of the detector’s response on particle hits at oblique angles and MCP-PMT performance at high illumination rates.

  20. Surface activated carbon nanospheres for fast adsorption of silver ions from aqueous solutions.

    PubMed

    Song, Xianghua; Gunawan, Poernomo; Jiang, Rongrong; Leong, Susanna Su Jan; Wang, Kean; Xu, Rong

    2011-10-30

    We report the synthesis and activation of colloidal carbon nanospheres (CNS) for adsorption of Ag(I) ions from aqueous solutions. CNS (400-500 nm in diameter) was synthesized via simple hydrothermal treatment of glucose solution. The surface of nonporous CNS after being activated by NaOH was enriched with -OH and -COO(-) functional groups. Despite the low surface area (<15m(2)/g), the activated CNS exhibited a high adsorption capacity of 152 mg silver/g. Under batch conditions, all Ag(I) ions can be completely adsorbed in less than 6 min with the initial Ag(I) concentrations lower than 2 ppm. This can be attributed to the minimum mass transfer resistance as Ag(I) ions were all deposited and reduced as Ag(0) nanoparticles on the external surface of CNS. The kinetic data can be well fitted to the pseudo-second-order kinetics model. The adsorbed silver can be easily recovered by dilute acid solutions and the CNS can be reactivated by the same treatment with NaOH solution. The excellent adsorption performance and reusability have also been demonstrated in a continuous mode. The NaOH activated CNS reported here could represent a new type of low-cost and efficient adsorbent nanomaterials for removal of trace Ag(I) ions for drinking water production.

  1. Accelerated susceptibility-based positive contrast imaging of MR compatible metallic devices based on modified fast spin echo sequences

    NASA Astrophysics Data System (ADS)

    Shi, Caiyun; Xie, Guoxi; Zhang, Yongqin; Zhang, Xiaoyong; Chen, Min; Su, Shi; Dong, Ying; Liu, Xin; Ji, Jim

    2017-04-01

    This study aims to develop an accelerated susceptibility-based positive contrast MR imaging method for visualizing MR compatible metallic devices. A modified fast spin echo sequence is used to accelerate data acquisition. Each readout gradient in the modified fast spin echo is slightly shifted by a short distance T shift. Phase changes accumulated within T shift are then used to calculate the susceptibility map by using a kernel deconvolution algorithm with a regularized ℓ1 minimization. To evaluate the proposed fast spin echo method, three phantom experiments were conducted and compared to a spin echo based technique and the gold standard CT for visualizing biopsy needles and brachytherapy seeds. Compared to the spin echo based technique, the data sampling speed of the proposed method was faster by 2–4 times while still being able to accurately visualize and identify the location of the biopsy needle and brachytherapy seeds. These results were confirmed by CT images of the same devices. Results also demonstrated that the proposed fast spin echo method can achieve good visualization of the brachytherapy seeds in positive contrast and in different orientations. It is also capable of correctly differentiating brachytherapy seeds from other similar structures on conventional magnitude images.

  2. Fast and highly specific DNA-based multiplex detection on a solid support.

    PubMed

    Barišić, Ivan; Kamleithner, Verena; Schönthaler, Silvia; Wiesinger-Mayr, Herbert

    2015-01-01

    Highly specific and fast multiplex detection methods are essential to conduct reasonable DNA-based diagnostics and are especially important to characterise infectious diseases. More than 1000 genetic targets such as antibiotic resistance genes, virulence factors and phylogenetic markers have to be identified as fast as possible to facilitate the correct treatment of a patient. In the present work, we developed a novel ligation-based DNA probe concept that was combined with the microarray technology and used it for the detection of bacterial pathogens. The novel linear chain (LNC) probes identified all tested species correctly within 1 h based on their 16S rRNA gene in a 25-multiplex reaction. Genomic DNA was used directly as template in the ligation reaction identifying as little as 10(7) cells without any pre-amplification. The high specificity was further demonstrated characterising a single nucleotide polymorphism leading to no false positive fluorescence signals of the untargeted single nucleotide polymorphism (SNP) variants. In comparison to conventional microarray probes, the sensitivity of the novel LNC3 probes was higher by a factor of 10 or more. In summary, we present a fast, simple, highly specific and sensitive multiplex detection method adaptable for a wide range of applications.

  3. Moment feature based fast feature extraction algorithm for moving object detection using aerial images.

    PubMed

    Saif, A F M Saifuddin; Prabuwono, Anton Satria; Mahayuddin, Zainal Rasyid

    2015-01-01

    Fast and computationally less complex feature extraction for moving object detection using aerial images from unmanned aerial vehicles (UAVs) remains as an elusive goal in the field of computer vision research. The types of features used in current studies concerning moving object detection are typically chosen based on improving detection rate rather than on providing fast and computationally less complex feature extraction methods. Because moving object detection using aerial images from UAVs involves motion as seen from a certain altitude, effective and fast feature extraction is a vital issue for optimum detection performance. This research proposes a two-layer bucket approach based on a new feature extraction algorithm referred to as the moment-based feature extraction algorithm (MFEA). Because a moment represents the coherent intensity of pixels and motion estimation is a motion pixel intensity measurement, this research used this relation to develop the proposed algorithm. The experimental results reveal the successful performance of the proposed MFEA algorithm and the proposed methodology.

  4. MetaSensing's FastGBSAR: ground based radar for deformation monitoring

    NASA Astrophysics Data System (ADS)

    Rödelsperger, Sabine; Meta, Adriano

    2014-10-01

    The continuous monitoring of ground deformation and structural movement has become an important task in engineering. MetaSensing introduces a novel sensor system, the Fast Ground Based Synthetic Aperture Radar (FastGBSAR), based on innovative technologies that have already been successfully applied to airborne SAR applications. The FastGBSAR allows the remote sensing of deformations of a slope or infrastructure from up to a distance of 4 km. The FastGBSAR can be setup in two different configurations: in Real Aperture Radar (RAR) mode it is capable of accurately measuring displacements along a linear range profile, ideal for monitoring vibrations of structures like bridges and towers (displacement accuracy up to 0.01 mm). Modal parameters can be determined within half an hour. Alternatively, in Synthetic Aperture Radar (SAR) configuration it produces two-dimensional displacement images with an acquisition time of less than 5 seconds, ideal for monitoring areal structures like dams, landslides and open pit mines (displacement accuracy up to 0.1 mm). The MetaSensing FastGBSAR is the first ground based SAR instrument on the market able to produce two-dimensional deformation maps with this high acquisition rate. By that, deformation time series with a high temporal and spatial resolution can be generated, giving detailed information useful to determine the deformation mechanisms involved and eventually to predict an incoming failure. The system is fully portable and can be quickly installed on bedrock or a basement. The data acquisition and processing can be fully automated leading to a low effort in instrument operation and maintenance. Due to the short acquisition time of FastGBSAR, the coherence between two acquisitions is very high and the phase unwrapping is simplified enormously. This yields a high density of resolution cells with good quality and high reliability of the acquired deformations. The deformation maps can directly be used as input into an Early

  5. HIGH RESOLUTION AND FAST SCANNING SQUID BASED NON-DESTRUCTIVE INSPECTION SYSTEM OF NIOBIUM SHEETS FOR SRF CAVITIES

    SciTech Connect

    SHU, QUAN-SHENG

    2008-06-08

    Applications in high energy physics accelerators and other fields require the use of thousands of superconducting RF (SRF) cavities that are made of high purity Nb material and the purity of niobium is critical for these cavities to reach the highest accelerating fields. Tantalum is the most prolific of metal inclusions, which can cause thermal breakdown and prevent the cavities from reaching their theoretical performance limits of 45-50 MV/m, and DOE Labs are searching for a technology that could detect small impurities in superconducting Nb sheets reaching the highest possible accelerating fields. The proposed innovative SQUID-based Nondestructive system can scan Niobium sheets used in the manufacturing of SRF cavities with both high speed and high resolution. A highly sensitive SQUID system with a gradiometer probe, non-magnetic dewar, data acquisition system, and a scanning system will be developed for fast detection of impurities in planar Nb sheets. In phase I, we will modify our existing SQUID-based eddy current system to detect 100 micron size Ta defects and a great effort will focus on achieving fast scanning of a large number of niobium sheets in a shorter time and with reasonable resolution. An older system operated by moving the sample 1 mm, stopping and waiting for 1-2 seconds, then activating a measurement by the SQUID after the short settle time is modified. A preliminary designed and implemented a SQUID scanning system that is fast and is capable of scanning a 30 cm x 30 cm Nb sheet in 15 minutes by continuously moving the table at speeds up to 10 mm/s while activating the SQUID at 1mm interval is modified and reached the Phase I goal of 100mm resolution. We have successfully demonstrated the feasibility that a fast speed SQUID scanner without sacrificing the resolution of detection can be done, and a data acquisition and analysis system is also preliminary developed. The SQUID based scanner will help reach the highest accelerating field in SRF

  6. Variable-cell double-ended surface walking method for fast transition state location of solid phase transitions.

    PubMed

    Zhang, Xiao-Jie; Liu, Zhi-Pan

    2015-10-13

    To identify the low energy pathway for solid-to-solid phase transition has been a great challenge in physics and material science. This work develops a new theoretical method, namely, variable-cell double-ended surface walking (VC-DESW) to locate the transition state (TS) and deduce the pathway in solid phase transition. Inherited from the DESW method ( J. Chem. Theory Comput. 2013 , 9 , 5745 ) for molecular systems, the VC-DESW method implements an efficient mechanism to couple the lattice and atom degrees of freedom. The method features with fast pseudopathway building and accurate TS location for solid phase transition systems without requiring expensive Hessian computation and iterative pathway optimization. A generalized coordinate, consisting of the lattice vectors and the scaled atomic coordinates, is designed for describing the crystal potential energy surface (PES), which is able to capture the anisotropic behavior in phase transition. By comparing with the existing method for solid phase transition in different systems, we show that the VC-DESW method can be much more efficient for finding the TS in crystal phase transition. With the combination of the recently developed unbiased stochastic surface walking pathway sampling method, the VC-DESW is further utilized to resolve the lowest energy pathway of SiO2 α-quartz to quartz-II phase transition from many likely reaction pathways. These new methods provide a powerful platform for understanding and predicting the solid phase transition mechanism and kinetics.

  7. Extremely Fast Numerical Integration of Ocean Surface Wave Dynamics: Building Blocks for a Higher Order Method

    DTIC Science & Technology

    2006-09-30

    αηηx + βη = 0 (1) where co = gh , α = 3co / 2h and . The KdV equation has the generalized Fourier solution (for periodic and/or quasi... numerical integration of the partial differential equations of surface water waves is the long-term goal of this work. The approach is a...applications of the method. APPROACH We first consider the shallow water equation known as the Korteweg-deVries ( KdV ) equation ): ηt + coηx

  8. Soft Surfaces for Fast Characterization and Positioning of Scanning Electrochemical Microscopy Nanoelectrode Tips.

    PubMed

    Gossage, Zachary T; Simpson, Burton H; Schorr, Noah B; Rodríguez-López, Joaquín

    2016-10-18

    The testing of nanoelectrode tips for scanning electrochemical microscopy (SECM) is a slow and cumbersome task that often results in untimely electrode breakage due to crashing against a substrate. Here, we evaluated approach curves of nano- and microelectrodes to soft surfaces using SECM for a rapid and more convenient characterization and positioning protocol. Soft surfaces consisted of either a submerged argon bubble or a thin polydimethylsiloxane (PDMS) layer. While approach curves to Ar bubbles in the presence of a surfactant were promising for the characterization of microelectrode tips, their performance with nanoelectrodes was deficient. In contrast, approach curves to PDMS films allowed the rapid positioning of nanoelectrodes as small as 30 nm radius at speeds up to 5 μm/s without the risk of breakage. The nanoelectrodes were able to approach the polymer films multiple times without affecting their electrochemical performance. Furthermore, using a half-coated substrate with PDMS, nanoelectrodes could be retracted and positioned very close to the bare, hard substrate for characterization with traditional approach curves. We estimate time savings on tip characterization/positioning on the order of 10- to 100-fold. This simple procedure is easily implemented without the requirement of additional devices supplementing existing commercial SECM instruments.

  9. Statistical Seasonal Sea Surface based Prediction Model

    NASA Astrophysics Data System (ADS)

    Suarez, Roberto; Rodriguez-Fonseca, Belen; Diouf, Ibrahima

    2014-05-01

    The interannual variability of the sea surface temperature (SST) plays a key role in the strongly seasonal rainfall regime on the West African region. The predictability of the seasonal cycle of rainfall is a field widely discussed by the scientific community, with results that fail to be satisfactory due to the difficulty of dynamical models to reproduce the behavior of the Inter Tropical Convergence Zone (ITCZ). To tackle this problem, a statistical model based on oceanic predictors has been developed at the Universidad Complutense of Madrid (UCM) with the aim to complement and enhance the predictability of the West African Monsoon (WAM) as an alternative to the coupled models. The model, called S4CAST (SST-based Statistical Seasonal Forecast) is based on discriminant analysis techniques, specifically the Maximum Covariance Analysis (MCA) and Canonical Correlation Analysis (CCA). Beyond the application of the model to the prediciton of rainfall in West Africa, its use extends to a range of different oceanic, atmospheric and helth related parameters influenced by the temperature of the sea surface as a defining factor of variability.

  10. A fast preamplifier concept for SiPM-based time-of-flight PET detectors

    NASA Astrophysics Data System (ADS)

    Huizenga, J.; Seifert, S.; Schreuder, F.; van Dam, H. T.; Dendooven, P.; Löhner, H.; Vinke, R.; Schaart, D. R.

    2012-12-01

    Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm×3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a 'slow' energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm×3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm×3 mm×5 mm LaBr3:Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

  11. Test of a prototype neutron spectrometer based on diamond detectors in a fast reactor

    SciTech Connect

    Osipenko, M.; Ripani, M.; Ricco, G.; Caiffi, B.; Pompili, F.; Pillon, M.; Angelone, M.; Verona-Rinati, G.; Cardarelli, R.; Argiro, S.

    2015-07-01

    A prototype of neutron spectrometer based on diamond detectors has been developed. This prototype consists of a {sup 6}Li neutron converter sandwiched between two CVD diamond crystals. The radiation hardness of the diamond crystals makes it suitable for applications in low power research reactors, while a low sensitivity to gamma rays and low leakage current of the detector permit to reach good energy resolution. A fast coincidence between two crystals is used to reject background. The detector was read out using two different electronic chains connected to it by a few meters of cable. The first chain was based on conventional charge-sensitive amplifiers, the other used a custom fast charge amplifier developed for this purpose. The prototype has been tested at various neutron sources and showed its practicability. In particular, the detector was calibrated in a TRIGA thermal reactor (LENA laboratory, University of Pavia) with neutron fluxes of 10{sup 8} n/cm{sup 2}s and at the 3 MeV D-D monochromatic neutron source named FNG (ENEA, Rome) with neutron fluxes of 10{sup 6} n/cm{sup 2}s. The neutron spectrum measurement was performed at the TAPIRO fast research reactor (ENEA, Casaccia) with fluxes of 10{sup 9} n/cm{sup 2}s. The obtained spectra were compared to Monte Carlo simulations, modeling detector response with MCNP and Geant4. (authors)

  12. Fast entropy-based CABAC rate estimation for mode decision in HEVC.

    PubMed

    Chen, Wei-Gang; Wang, Xun

    2016-01-01

    High efficiency video coding (HEVC) seeks the best code tree configuration, the best prediction unit division and the prediction mode, by evaluating the rate-distortion functional in a recursive way and using a "try all and select the best" strategy. Further, HEVC only supports context adaptive binary arithmetic coding (CABAC), which has the disadvantage of being highly sequential and having strong data dependencies, as the entropy coder. So, the development of a fast rate estimation algorithm for CABAC-based coding has a great practical significance for mode decision in HEVC. There are three elementary steps in CABAC encoding process: binarization, context modeling, and binary arithmetic coding. Typical approaches to fast CABAC rate estimation simplify or eliminate the last two steps, but leave the binarization step unchanged. To maximize the reduction of computational complexity, we propose a fast entropy-based CABAC rate estimator in this paper. It eliminates not only the modeling and the coding steps, but also the binarization step. Experimental results demonstrate that the proposed estimator is able to reduce the computational complexity of the mode decision in HEVC by 9-23 % with negligible PSNR loss and BD-rate increment, and therefore exhibits applicability to practical HEVC encoder implementation.

  13. Dynamical programming based turbulence velocimetry for fast visible imaging of tokamak plasma

    NASA Astrophysics Data System (ADS)

    Banerjee, Santanu; Zushi, H.; Nishino, N.; Mishra, K.; Onchi, T.; Kuzmin, A.; Nagashima, Y.; Hanada, K.; Nakamura, K.; Idei, H.; Hasegawa, M.; Fujisawa, A.

    2015-03-01

    An orthogonal dynamic programming (ODP) based particle image velocimetry (PIV) technique is developed to measure the time resolved flow field of the fluctuating structures at the plasma edge and scrape off layer (SOL) of tokamaks. This non-intrusive technique can provide two dimensional velocity fields at high spatial and temporal resolution from a fast framing image sequence and hence can provide better insights into plasma flow as compared to conventional probe measurements. Applicability of the technique is tested with simulated image pairs. Finally, it is applied to tangential fast visible images of QUEST plasma to estimate the SOL flow in inboard poloidal null-natural divertor configuration. This technique is also applied to investigate the intricate features of the core of the run-away dominated phase following the injection of a large amount of neutrals in the target Ohmic plasma. Development of the ODP-PIV code and its applicability on actual plasma images is reported.

  14. A fast multispectral light synthesiser based on LEDs and a diffraction grating

    PubMed Central

    Belušič, Gregor; Ilić, Marko; Meglič, Andrej; Pirih, Primož

    2016-01-01

    Optical experiments often require fast-switching light sources with adjustable bandwidths and intensities. We constructed a wavelength combiner based on a reflective planar diffraction grating and light emitting diodes with emission peaks from 350 to 630 nm that were positioned at the angles corresponding to the first diffraction order of the reversed beam. The combined output beam was launched into a fibre. The spacing between 22 equally wide spectral bands was about 15 nm. The time resolution of the pulse-width modulation drivers was 1 ms. The source was validated with a fast intracellular measurement of the spectral sensitivity of blowfly photoreceptors. In hyperspectral imaging of Xenopus skin circulation, the wavelength resolution was adequate to resolve haemoglobin absorption spectra. The device contains no moving parts, has low stray light and is intrinsically capable of multi-band output. Possible applications include visual physiology, biomedical optics, microscopy and spectroscopy. PMID:27558155

  15. Development of fast neutron radiography system based on portable neutron generator

    NASA Astrophysics Data System (ADS)

    Yi, Chia Jia; Nilsuwankosit, Sunchai

    2016-01-01

    Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.

  16. Preconditioning based on Calderon's formulae for periodic fast multipole methods for Helmholtz' equation

    NASA Astrophysics Data System (ADS)

    Niino, Kazuki; Nishimura, Naoshi

    2012-01-01

    Solution of periodic boundary value problems is of interest in various branches of science and engineering such as optics, electromagnetics and mechanics. In our previous studies we have developed a periodic fast multipole method (FMM) as a fast solver of wave problems in periodic domains. It has been found, however, that the convergence of the iterative solvers for linear equations slows down when the solutions show anomalies related to the periodicity of the problems. In this paper, we propose preconditioning schemes based on Calderon's formulae to accelerate convergence of iterative solvers in the periodic FMM for Helmholtz' equations. The proposed preconditioners can be implemented more easily than conventional ones. We present several numerical examples to test the performance of the proposed preconditioners. We show that the effectiveness of these preconditioners is definite even near anomalies.

  17. Improved FFT-based numerical inversion of Laplace transforms via fast Hartley transform algorithm

    NASA Technical Reports Server (NTRS)

    Hwang, Chyi; Lu, Ming-Jeng; Shieh, Leang S.

    1991-01-01

    The disadvantages of numerical inversion of the Laplace transform via the conventional fast Fourier transform (FFT) are identified and an improved method is presented to remedy them. The improved method is based on introducing a new integration step length Delta(omega) = pi/mT for trapezoidal-rule approximation of the Bromwich integral, in which a new parameter, m, is introduced for controlling the accuracy of the numerical integration. Naturally, this method leads to multiple sets of complex FFT computations. A new inversion formula is derived such that N equally spaced samples of the inverse Laplace transform function can be obtained by (m/2) + 1 sets of N-point complex FFT computations or by m sets of real fast Hartley transform (FHT) computations.

  18. A fast multispectral light synthesiser based on LEDs and a diffraction grating

    NASA Astrophysics Data System (ADS)

    Belušič, Gregor; Ilić, Marko; Meglič, Andrej; Pirih, Primož

    2016-08-01

    Optical experiments often require fast-switching light sources with adjustable bandwidths and intensities. We constructed a wavelength combiner based on a reflective planar diffraction grating and light emitting diodes with emission peaks from 350 to 630 nm that were positioned at the angles corresponding to the first diffraction order of the reversed beam. The combined output beam was launched into a fibre. The spacing between 22 equally wide spectral bands was about 15 nm. The time resolution of the pulse-width modulation drivers was 1 ms. The source was validated with a fast intracellular measurement of the spectral sensitivity of blowfly photoreceptors. In hyperspectral imaging of Xenopus skin circulation, the wavelength resolution was adequate to resolve haemoglobin absorption spectra. The device contains no moving parts, has low stray light and is intrinsically capable of multi-band output. Possible applications include visual physiology, biomedical optics, microscopy and spectroscopy.

  19. Response of a Si-diode-based device to fast neutrons.

    PubMed

    Spurný, Frantisek

    2005-02-01

    Semiconductor devices based on a Si-detector are frequently used for charged particle's detection; one application being in the investigation of cosmic radiation fields. From the spectra of energy deposition events in such devices, the total energy deposited by the radiation in silicon can be derived. This contribution presents the results of studies concerning the response of this type of detector to fast neutrons. First, the spectrum of energy deposition was established in fast neutron radiation fields with average energies from 0.5 to 50 MeV. It was found that these spectra vary significantly with the neutron energy. The comparison with the spectra registered in photon beams permitted an estimation of the part of energy deposited that could be attributed to neutrons. It was found that this part increases rapidly with neutron energy. The possibilities to use this type of detector for neutron detection and dosimetry for radiation protection are analysed and discussed.

  20. Development of fast neutron radiography system based on portable neutron generator

    SciTech Connect

    Yi, Chia Jia Nilsuwankosit, Sunchai

    2016-01-22

    Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.

  1. Fast, high-resolution surface potential measurements in air with heterodyne Kelvin probe force microscopy

    NASA Astrophysics Data System (ADS)

    Garrett, Joseph L.; Munday, Jeremy N.

    2016-06-01

    Kelvin probe force microscopy (KPFM) adapts an atomic force microscope to measure electric potential on surfaces at nanometer length scales. Here we demonstrate that Heterodyne-KPFM enables scan rates of several frames per minute in air, and concurrently maintains spatial resolution and voltage sensitivity comparable to frequency-modulation KPFM, the current spatial resolution standard. Two common classes of topography-coupled artifacts are shown to be avoidable with H-KPFM. A second implementation of H-KPFM is also introduced, in which the voltage signal is amplified by the first cantilever resonance for enhanced sensitivity. The enhanced temporal resolution of H-KPFM can enable the imaging of many dynamic processes, such as such as electrochromic switching, phase transitions, and device degredation (battery, solar, etc), which take place over seconds to minutes and involve changes in electric potential at nanometer lengths.

  2. The evolution of spatial ordering of oil drops fast spreading on a water surface

    NASA Astrophysics Data System (ADS)

    Yamamoto, Daigo; Nakajima, Chika; Shioi, Akihisa; Krafft, Marie Pierre; Yoshikawa, Kenichi

    2015-05-01

    The design of dynamically self-assembled systems is of high interest in science and technology. Here, we report a unique cascade in the self-ordering of droplets accompanied by a dewetting transition. The dynamic self-emergent droplets are observed when a thin liquid layer of an immiscible fluorocarbon oil (perfluorooctyl bromide, PFOB) is placed on a water surface. Due to the gradual evaporation of PFOB, a circular PFOB-free domain appears as a result of a local dewetting transition. A circular pearling structure is generated at the rim with the growth of the dewetting hole. As the next stage, linear arrays of droplets are generated in a radial manner from the centre of the hole. These one-dimensional arrangements then evolve into two-dimensional hexagonal arrays of microdroplets through collective rhythmical shrinking/expanding motions. The emergence of such dynamic patterns is discussed in terms of the nonlinear kinetics of the dewetting transition under thermodynamically dissipative conditions.

  3. A VLSI Architecture with Multiple Fast Store-Based Block Parallel Processing for Output Probability and Likelihood Score Computations in HMM-Based Isolated Word Recognition

    NASA Astrophysics Data System (ADS)

    Nakamura, Kazuhiro; Shimazaki, Ryo; Yamamoto, Masatoshi; Takagi, Kazuyoshi; Takagi, Naofumi

    This paper presents a memory-efficient VLSI architecture for output probability computations (OPCs) of continuous hidden Markov models (HMMs) and likelihood score computations (LSCs). These computations are the most time consuming part of HMM-based isolated word recognition systems. We demonstrate multiple fast store-based block parallel processing (MultipleFastStoreBPP) for OPCs and LSCs and present a VLSI architecture that supports it. Compared with conventional fast store-based block parallel processing (FastStoreBPP) and stream-based block parallel processing (StreamBPP) architectures, the proposed architecture requires fewer registers and less processing time. The processing elements (PEs) used in the FastStoreBPP and StreamBPP architectures are identical to those used in the MultipleFastStoreBPP architecture. From a VLSI architectural viewpoint, a comparison shows that the proposed architecture is an improvement over the others, through efficient use of PEs and registers for storing input feature vectors.

  4. Fast-Fourier-transform based numerical integration method for the Rayleigh-Sommerfeld diffraction formula

    NASA Astrophysics Data System (ADS)

    Shen, Fabin; Wang, Anbo

    2006-02-01

    The numerical calculation of the Rayleigh-Sommerfeld diffraction integral is investigated. The implementation of a fast-Fourier-transform (FFT) based direct integration (FFT-DI) method is presented, and Simpson's rule is used to improve the calculation accuracy. The sampling interval, the size of the computation window, and their influence on numerical accuracy and on computational complexity are discussed for the FFT-DI and the FFT-based angular spectrum (FFT-AS) methods. The performance of the FFT-DI method is verified by numerical simulation and compared with that of the FFT-AS method.

  5. Improving abdomen tumor low-dose CT images using a fast dictionary learning based processing

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Yin, Xindao; Shi, Luyao; Shu, Huazhong; Luo, Limin; Coatrieux, Jean-Louis; Toumoulin, Christine

    2013-08-01

    In abdomen computed tomography (CT), repeated radiation exposures are often inevitable for cancer patients who receive surgery or radiotherapy guided by CT images. Low-dose scans should thus be considered in order to avoid the harm of accumulative x-ray radiation. This work is aimed at improving abdomen tumor CT images from low-dose scans by using a fast dictionary learning (DL) based processing. Stemming from sparse representation theory, the proposed patch-based DL approach allows effective suppression of both mottled noise and streak artifacts. The experiments carried out on clinical data show that the proposed method brings encouraging improvements in abdomen low-dose CT images with tumors.

  6. Surface Functionalization of Graphene-based Materials

    NASA Astrophysics Data System (ADS)

    Mathkar, Akshay

    Graphene-based materials have generated tremendous interest in the past decade. Manipulating their characteristics using wet-chemistry methods holds distinctive value, as it provides a means towards scaling up, while not being limited by yield. The majority of this thesis focuses on the surface functionalization of graphene oxide (GO), which has drawn tremendous attention as a tunable precursor due to its readily chemically manipulable surface and richly functionalized basal plane. Firstly, a room-temperature based method is presented to reduce GO stepwise, with each organic moiety being removed sequentially. Characterization confirms the carbonyl group to be reduced first, while the tertiary alcohol is reduced last, as the optical gap decrease from 3.5 eV down to 1 eV. This provides greater control over GO, which is an inhomogeneous system, and is the first study to elucidate the order of removal of each functional group. In addition to organically manipulating GO, this thesis also reports a chemical methodology to inorganically functionalize GO and tune its wetting characteristics. A chemical method to covalently attach fluorine atoms in the form of tertiary alkyl fluorides is reported, and confirmed by MAS 13C NMR, as two forms of fluorinated graphene oxide (FGO) with varying C/F and C/O ratios are synthesized. Introducing C-F bonds decreases the overall surface free energy, which drastically reduces GO's wetting behavior, especially in its highly fluorinated form. Ease of solution processing leads to development of sprayable inks that are deposited on a range of porous and nonporous surfaces to impart amphiphobicity. This is the first report that tunes the wetting characteristics of GO. Lastly as a part of a collaboration with ConocoPhillips, another class of carbon nanomaterials - carbon nanotubes (CNTs), have been inorganically functionalized to repel 30 wt% MEA, a critical solvent in CO 2 recovery. In addition to improving the solution processability of CNTs

  7. Microwave-Accelerated Surface Plasmon-Coupled Directional Luminescence: application to fast and sensitive assays in buffer, human serum and whole blood.

    PubMed

    Aslan, Kadir; Malyn, Stuart N; Geddes, Chris D

    2007-05-31

    The applicability of a new technique, Microwave-Accelerated Surface Plasmon-Coupled Luminescence (MA-SPCL) for fast and sensitive bioassays in buffer, serum and whole blood using quantum dots as luminescence reporters is demonstrated. In this regard, a model bioassay based on the well-known interactions of biotin and streptavidin is used. Using MA-SPCL, the bioassay was kinetically completed within 1 min with the use of low power microwave heating as compared to the identical bioassay which took in excess of 30 min to reach >95% completion at room temperature, a 30-fold increase in assay kinetics. The luminescence emission from the quantum dots was coupled to surface plasmons of the gold film, enabling the detection of the luminescence emission in a highly directional fashion as compared to the normal isotropic emission, for enhanced sensitivity and detection. The combined effect of microwaves for faster assay kinetics, with surface plasmon-coupled luminescence for sensitive luminescence measurements, has also made possible the demonstration of the use of the MA-SPCL technique for assays run in complex media, such as human serum and whole blood, where the same assay could not be performed at room temperature due to the coagulation of blood. In the MA-SPCL assay run in serum and whole blood, the luminescence intensity from 33 nM quantum dots was 75% and 20% that of the luminescence intensity from the assay run in buffer, with a signal to noise ratio of 12.5 and 3, respectively.

  8. Standing surface acoustic wave based cell coculture.

    PubMed

    Li, Sixing; Guo, Feng; Chen, Yuchao; Ding, Xiaoyun; Li, Peng; Wang, Lin; Cameron, Craig E; Huang, Tony Jun

    2014-10-07

    Precise reconstruction of heterotypic cell-cell interactions in vitro requires the coculture of different cell types in a highly controlled manner. In this article, we report a standing surface acoustic wave (SSAW)-based cell coculture platform. In our approach, different types of cells are patterned sequentially in the SSAW field to form an organized cell coculture. To validate our platform, we demonstrate a coculture of epithelial cancer cells and endothelial cells. Real-time monitoring of cell migration dynamics reveals increased cancer cell mobility when cancer cells are cocultured with endothelial cells. Our SSAW-based cell coculture platform has the advantages of contactless cell manipulation, high biocompatibility, high controllability, simplicity, and minimal interference of the cellular microenvironment. The SSAW technique demonstrated here can be a valuable analytical tool for various biological studies involving heterotypic cell-cell interactions.

  9. Hand gesture recognition based on surface electromyography.

    PubMed

    Samadani, Ali-Akbar; Kulic, Dana

    2014-01-01

    Human hands are the most dexterous of human limbs and hand gestures play an important role in non-verbal communication. Underlying electromyograms associated with hand gestures provide a wealth of information based on which varying hand gestures can be recognized. This paper develops an inter-individual hand gesture recognition model based on Hidden Markov models that receives surface electromyography (sEMG) signals as inputs and predicts a corresponding hand gesture. The developed recognition model is tested with a dataset of 10 various hand gestures performed by 25 subjects in a leave-one-subject-out cross validation and an inter-individual recognition rate of 79% was achieved. The promising recognition rate demonstrates the efficacy of the proposed approach for discriminating between gesture-specific sEMG signals and could inform the design of sEMG-controlled prostheses and assistive devices.

  10. Standing Surface Acoustic Wave Based Cell Coculture

    PubMed Central

    2015-01-01

    Precise reconstruction of heterotypic cell–cell interactions in vitro requires the coculture of different cell types in a highly controlled manner. In this article, we report a standing surface acoustic wave (SSAW)-based cell coculture platform. In our approach, different types of cells are patterned sequentially in the SSAW field to form an organized cell coculture. To validate our platform, we demonstrate a coculture of epithelial cancer cells and endothelial cells. Real-time monitoring of cell migration dynamics reveals increased cancer cell mobility when cancer cells are cocultured with endothelial cells. Our SSAW-based cell coculture platform has the advantages of contactless cell manipulation, high biocompatibility, high controllability, simplicity, and minimal interference of the cellular microenvironment. The SSAW technique demonstrated here can be a valuable analytical tool for various biological studies involving heterotypic cell–cell interactions. PMID:25232648

  11. Feature Article: Fast scanning tunnelling microscopy as a tool to understand changes on metal surfaces: from nanostructures to single atoms

    NASA Astrophysics Data System (ADS)

    Morgenstern, Karina

    2005-03-01

    The Feature Article [1] describes how structural changes in metallic nanostructures can be followed with fast scanning tunneling microscopy (STM). The title page shows the same spot of a Ag(111) surface at room temperature, imaged with STM approximately one hour apart. Intrinsic changes to prepared nano-structures are marked as Brownian motion of vacancy islands (rectangle), coalescence of two vacancy islands (hexagon), and decay of an adatom island (circle).Karina Morgenstern is now professor at the University of Hannover. Her research is placed within the field of nanoscience and is in particular devoted to thermally activated processes of metallic nanostructures, electronically activated reactions of molecules on metallic surfaces, and water-metal interactions.The present issue of physica status solidi (b) also contains the article Apperance of copper d9 defect centres in wide-gap CdSe nanoparticles: A high-fequency EPR study by N. R. J. Poolton et al. as Editor's Choice [2] as well as several papers on electrical and nonlinear optical properties from the European Conference on Organised Films (ECOF 2004) chaired by José Antonio de Saja, Valladolid.

  12. On the chemical processing of hydrocarbon surfaces by fast oxygen ions.

    PubMed

    Ennis, Courtney; Yuan, Hanqiu; Sibener, S J; Kaiser, Ralf I

    2011-10-21

    Solid methane (CH(4)), ethane (C(2)H(6)), and ethylene (C(2)H(4)) ices (thickness: 120 ± 40 nm; 10 K), as well as high-density polyethylene (HDPE: [C(2)H(4)](n)) films (thickness: 130 ± 20 nm; 10, 100, and 300 K), were irradiated with mono-energetic oxygen ions (Φ ~ 6 × 10(15) cm(-2)) of a kinetic energy of 5 keV to simulate the exposure of Solar System hydrocarbon ices and aerospace polymers to oxygen ions sourced from the solar wind and planetary magnetospheres. On-line Fourier-transform infrared spectroscopy (FTIR) was used to identify the following O(+) induced reaction pathways in the solid-state: (i) ethane formation from methane ice via recombination of methyl (CH(3)) radicals, (ii) ethane conversion back to methane via methylene (CH(2)) retro-insertion, (iii) ethane decomposing to acetylene via ethylene through successive hydrogen elimination steps, and (iv) ethylene conversion to acetylene via hydrogen elimination. No changes were observed in the irradiated PE samples via infrared spectroscopy. In addition, mass spectrometry detected small abundances of methanol (CH(3)OH) sublimed from the irradiated methane and ethane condensates during controlled heating. The detection of methanol suggests an implantation and neutralization of the oxygen ions within the surface where atomic oxygen (O) then undergoes insertion into a C-H bond of methane. Atomic hydrogen (H) recombination in forming molecular hydrogen and recombination of implanted oxygen atoms to molecular oxygen (O(2)) are also inferred to proceed at high cross-sections. A comparison of the reaction rates and product yields to those obtained from experiments involving 5 keV electrons, suggests that the chemical alteration of the hydrocarbon ice samples is driven primarily by electronic stopping interactions and to a lesser extent by nuclear interactions.

  13. A CFD-based wind solver for a fast response transport and dispersion model

    SciTech Connect

    Gowardhan, Akshay A; Brown, Michael J; Pardyjak, Eric R; Senocak, Inanc

    2010-01-01

    In many cities, ambient air quality is deteriorating leading to concerns about the health of city inhabitants. In urban areas with narrow streets surrounded by clusters of tall buildings, called street canyons, air pollution from traffic emissions and other sources is difficult to disperse and may accumulate resulting in high pollutant concentrations. For various situations, including the evacuation of populated areas in the event of an accidental or deliberate release of chemical, biological and radiological agents, it is important that models should be developed that produce urban flow fields quickly. For these reasons it has become important to predict the flow field in urban street canyons. Various computational techniques have been used to calculate these flow fields, but these techniques are often computationally intensive. Most fast response models currently in use are at a disadvantage in these cases as they are unable to correlate highly heterogeneous urban structures with the diagnostic parameterizations on which they are based. In this paper, a fast and reasonably accurate computational fluid dynamics (CFD) technique that solves the Navier-Stokes equations for complex urban areas has been developed called QUIC-CFD (Q-CFD). This technique represents an intermediate balance between fast (on the order of minutes for a several block problem) and reasonably accurate solutions. The paper details the solution procedure and validates this model for various simple and complex urban geometries.

  14. Accelerated materials design of fast oxygen ionic conductors based on first principles calculations

    NASA Astrophysics Data System (ADS)

    He, Xingfeng; Mo, Yifei

    Over the past decades, significant research efforts have been dedicated to seeking fast oxygen ion conductor materials, which have important technological applications in electrochemical devices such as solid oxide fuel cells, oxygen separation membranes, and sensors. Recently, Na0.5Bi0.5TiO3 (NBT) was reported as a new family of fast oxygen ionic conductor. We will present our first principles computation study aims to understand the O diffusion mechanisms in the NBT material and to design this material with enhanced oxygen ionic conductivity. Using the NBT materials as an example, we demonstrate the computation capability to evaluate the phase stability, chemical stability, and ionic diffusion of the ionic conductor materials. We reveal the effects of local atomistic configurations and dopants on oxygen diffusion and identify the intrinsic limiting factors in increasing the ionic conductivity of the NBT materials. Novel doping strategies were predicted and demonstrated by the first principles calculations. In particular, the K doped NBT compound achieved good phase stability and an order of magnitude increase in oxygen ionic conductivity of up to 0.1 S cm-1 at 900 K compared to the experimental Mg doped compositions. Our results provide new avenues for the future design of the NBT materials and demonstrate the accelerated design of new ionic conductor materials based on first principles techniques. This computation methodology and workflow can be applied to the materials design of any (e.g. Li +, Na +) fast ion-conducting materials.

  15. Fast Fourier transform based direct integration algorithm for the linear canonical transform

    NASA Astrophysics Data System (ADS)

    Wang, Dayong; Liu, Changgeng; Wang, Yunxin; Zhao, Jie

    2011-03-01

    The linear canonical transform(LCT) is a parameterized linear integral transform, which is the general case of many well-known transforms such as the Fourier transform(FT), the fractional Fourier transform(FRT) and the Fresnel transform(FST). These integral transforms are of great importance in wave propagation problems because they are the solutions of the wave equation under a variety of circumstances. In optics, the LCT can be used to model paraxial free space propagation and other quadratic phase systems such as lens and graded-index media. A number of algorithms have been presented to fast compute the LCT. When they are used to compute the LCT, the sampling period in the transform domain is dependent on that in the signal domain. This drawback limits their applicability in some cases such as color digital holography. In this paper, a Fast-Fourier-Transform-based Direct Integration algorithm(FFT-DI) for the LCT is presented. The FFT-DI is a fast computational method of the Direct Integration(DI) for the LCT. It removes the dependency of the sampling period in the transform domain on that in the signal domain. Simulations and experimental results are presented to validate this idea.

  16. Fast Fourier transform based direct integration algorithm for the linear canonical transform

    NASA Astrophysics Data System (ADS)

    Wang, Dayong; Liu, Changgeng; Wang, Yunxin; Zhao, Jie

    2010-07-01

    The linear canonical transform(LCT) is a parameterized linear integral transform, which is the general case of many well-known transforms such as the Fourier transform(FT), the fractional Fourier transform(FRT) and the Fresnel transform(FST). These integral transforms are of great importance in wave propagation problems because they are the solutions of the wave equation under a variety of circumstances. In optics, the LCT can be used to model paraxial free space propagation and other quadratic phase systems such as lens and graded-index media. A number of algorithms have been presented to fast compute the LCT. When they are used to compute the LCT, the sampling period in the transform domain is dependent on that in the signal domain. This drawback limits their applicability in some cases such as color digital holography. In this paper, a Fast-Fourier-Transform-based Direct Integration algorithm(FFT-DI) for the LCT is presented. The FFT-DI is a fast computational method of the Direct Integration(DI) for the LCT. It removes the dependency of the sampling period in the transform domain on that in the signal domain. Simulations and experimental results are presented to validate this idea.

  17. Fast and sensitive optical toxicity bioassay based on dual wavelength analysis of bacterial ferricyanide reduction kinetics.

    PubMed

    Pujol-Vila, F; Vigués, N; Díaz-González, M; Muñoz-Berbel, X; Mas, J

    2015-05-15

    Global urban and industrial growth, with the associated environmental contamination, is promoting the development of rapid and inexpensive general toxicity methods. Current microbial methodologies for general toxicity determination rely on either bioluminescent bacteria and specific medium solution (i.e. Microtox(®)) or low sensitivity and diffusion limited protocols (i.e. amperometric microbial respirometry). In this work, fast and sensitive optical toxicity bioassay based on dual wavelength analysis of bacterial ferricyanide reduction kinetics is presented, using Escherichia coli as a bacterial model. Ferricyanide reduction kinetic analysis (variation of ferricyanide absorption with time), much more sensitive than single absorbance measurements, allowed for direct and fast toxicity determination without pre-incubation steps (assay time=10 min) and minimizing biomass interference. Dual wavelength analysis at 405 (ferricyanide and biomass) and 550 nm (biomass), allowed for ferricyanide monitoring without interference of biomass scattering. On the other hand, refractive index (RI) matching with saccharose reduced bacterial light scattering around 50%, expanding the analytical linear range in the determination of absorbent molecules. With this method, different toxicants such as metals and organic compounds were analyzed with good sensitivities. Half maximal effective concentrations (EC50) obtained after 10 min bioassay, 2.9, 1.0, 0.7 and 18.3 mg L(-1) for copper, zinc, acetic acid and 2-phenylethanol respectively, were in agreement with previously reported values for longer bioassays (around 60 min). This method represents a promising alternative for fast and sensitive water toxicity monitoring, opening the possibility of quick in situ analysis.

  18. Fast calculation method for computer-generated cylindrical holograms based on the three-dimensional Fourier spectrum.

    PubMed

    Sando, Yusuke; Barada, Daisuke; Jackin, Boaz Jessie; Yatagai, Toyohiko

    2013-12-01

    The relation between a three-dimensional (3D) object and its diffracted wavefront in the 3D Fourier space is discussed at first and then a rigorous diffraction formula onto cylindrical surfaces is derived. The azimuthal direction and the spatial frequency direction corresponding to height can be expressed with a one-dimensional (1D) convolution integral and a 1D inverse Fourier transform in the 3D Fourier space, respectively, and fast Fourier transforms are available for fast calculation. A numerical simulation of a diffracted wavefront on cylindrical surfaces is presented. An alternative optical experiment equivalent of the optical reconstruction from cylindrical holograms is also demonstrated.

  19. Fast calculation with point-based method to make CGHs of the polygon model

    NASA Astrophysics Data System (ADS)

    Ogihara, Yuki; Ichikawa, Tsubasa; Sakamoto, Yuji

    2014-02-01

    Holography is one of the three-dimensional technology. Light waves from an object are recorded and reconstructed by using a hologram. Computer generated holograms (CGHs), which are made by simulating light propagation using a computer, are able to represent virtual object. However, an enormous amount of computation time is required to make CGHs. There are two primary methods of calculating CGHs: the polygon-based method and the point-based method. In the polygon-based method with Fourier transforms, CGHs are calculated using a fast Fourier transform (FFT). The calculation of complex objects composed of multiple polygons requires as many FFTs, so unfortunately the calculation time become enormous. In contrast, in the point-based method, it is easy to express complex objects, an enormous calculation time is still required. Graphics processing units (GPUs) have been used to speed up the calculations of point-based method. Because a GPU is specialized for parallel computation and CGH calculation can be calculated independently for each pixel. However, expressing a planar object by the point-based method requires a signi cant increase in the density of points and consequently in the number of point light sources. In this paper, we propose a fast calculation algorithm to express planar objects by the point-based method with a GPU. The proposed method accelerate calculation by obtaining the distance between a pixel and the point light source from the adjacent point light source by a difference method. Under certain speci ed conditions, the difference between adjacent object points becomes constant, so the distance is obtained by only an additions. Experimental results showed that the proposed method is more effective than the polygon-based method with FFT when the number of polygons composing an objects are high.

  20. Fast Reactor Based on the Self-Sustained Regime of Nuclear Burning Wave

    NASA Astrophysics Data System (ADS)

    Fomin, S. P.; Mel'nik, Yu. P.; Pilipenko, V. V.; Shul'ga, N. F.

    An approach for description of the space-time evolution of self-organizing nuclear burning wave regime in a critical fast neutron reactor has been developed in the effective multigroup approximation. It is based on solving the non-stationary neutron diffusion equation together with the fuel burn-up equations and the equations of nuclear kinetics for delayed neutron precursor nuclei. The calculations have been carried out in the plane one-dimensional model for a two-zone homogeneous reactor with the metal U-Pu fuel, the Na coolant and constructional material Fe.

  1. Fast and accurate computation of system matrix for area integral model-based algebraic reconstruction technique

    NASA Astrophysics Data System (ADS)

    Zhang, Shunli; Zhang, Dinghua; Gong, Hao; Ghasemalizadeh, Omid; Wang, Ge; Cao, Guohua

    2014-11-01

    Iterative algorithms, such as the algebraic reconstruction technique (ART), are popular for image reconstruction. For iterative reconstruction, the area integral model (AIM) is more accurate for better reconstruction quality than the line integral model (LIM). However, the computation of the system matrix for AIM is more complex and time-consuming than that for LIM. Here, we propose a fast and accurate method to compute the system matrix for AIM. First, we calculate the intersection of each boundary line of a narrow fan-beam with pixels in a recursive and efficient manner. Then, by grouping the beam-pixel intersection area into six types according to the slopes of the two boundary lines, we analytically compute the intersection area of the narrow fan-beam with the pixels in a simple algebraic fashion. Overall, experimental results show that our method is about three times faster than the Siddon algorithm and about two times faster than the distance-driven model (DDM) in computation of the system matrix. The reconstruction speed of our AIM-based ART is also faster than the LIM-based ART that uses the Siddon algorithm and DDM-based ART, for one iteration. The fast reconstruction speed of our method was accomplished without compromising the image quality.

  2. A Fast and Precise Indoor Localization Algorithm Based on an Online Sequential Extreme Learning Machine †

    PubMed Central

    Zou, Han; Lu, Xiaoxuan; Jiang, Hao; Xie, Lihua

    2015-01-01

    Nowadays, developing indoor positioning systems (IPSs) has become an attractive research topic due to the increasing demands on location-based service (LBS) in indoor environments. WiFi technology has been studied and explored to provide indoor positioning service for years in view of the wide deployment and availability of existing WiFi infrastructures in indoor environments. A large body of WiFi-based IPSs adopt fingerprinting approaches for localization. However, these IPSs suffer from two major problems: the intensive costs of manpower and time for offline site survey and the inflexibility to environmental dynamics. In this paper, we propose an indoor localization algorithm based on an online sequential extreme learning machine (OS-ELM) to address the above problems accordingly. The fast learning speed of OS-ELM can reduce the time and manpower costs for the offline site survey. Meanwhile, its online sequential learning ability enables the proposed localization algorithm to adapt in a timely manner to environmental dynamics. Experiments under specific environmental changes, such as variations of occupancy distribution and events of opening or closing of doors, are conducted to evaluate the performance of OS-ELM. The simulation and experimental results show that the proposed localization algorithm can provide higher localization accuracy than traditional approaches, due to its fast adaptation to various environmental dynamics. PMID:25599427

  3. A fast and precise indoor localization algorithm based on an online sequential extreme learning machine.

    PubMed

    Zou, Han; Lu, Xiaoxuan; Jiang, Hao; Xie, Lihua

    2015-01-15

    Nowadays, developing indoor positioning systems (IPSs) has become an attractive research topic due to the increasing demands on location-based service (LBS) in indoor environments. WiFi technology has been studied and explored to provide indoor positioning service for years in view of the wide deployment and availability of existing WiFi infrastructures in indoor environments. A large body of WiFi-based IPSs adopt fingerprinting approaches for localization. However, these IPSs suffer from two major problems: the intensive costs of manpower and time for offline site survey and the inflexibility to environmental dynamics. In this paper, we propose an indoor localization algorithm based on an online sequential extreme learning machine (OS-ELM) to address the above problems accordingly. The fast learning speed of OS-ELM can reduce the time and manpower costs for the offline site survey. Meanwhile, its online sequential learning ability enables the proposed localization algorithm to adapt in a timely manner to environmental dynamics. Experiments under specific environmental changes, such as variations of occupancy distribution and events of opening or closing of doors, are conducted to evaluate the performance of OS-ELM. The simulation and experimental results show that the proposed localization algorithm can provide higher localization accuracy than traditional approaches, due to its fast adaptation to various environmental dynamics.

  4. Profiling Fast Healthcare Interoperability Resources (FHIR) of Family Health History based on the Clinical Element Models

    PubMed Central

    Lee, Jaehoon; Hulse, Nathan C.; Wood, Grant M.; Oniki, Thomas A.; Huff, Stanley M.

    2016-01-01

    In this study we developed a Fast Healthcare Interoperability Resources (FHIR) profile to support exchanging a full pedigree based family health history (FHH) information across multiple systems and applications used by clinicians, patients, and researchers. We used previously developed clinical element models (CEMs) that are capable of representing the FHH information, and derived essential data elements including attributes, constraints, and value sets. We analyzed gaps between the FHH CEM elements and existing FHIR resources. Based on the analysis, we developed a profile that consists of 1) FHIR resources for essential FHH data elements, 2) extensions for additional elements that were not covered by the resources, and 3) a structured definition to integrate patient and family member information in a FHIR message. We implemented the profile using an open-source based FHIR framework and validated it using patient-entered FHH data that was captured through a locally developed FHH tool. PMID:28269871

  5. Profiling Fast Healthcare Interoperability Resources (FHIR) of Family Health History based on the Clinical Element Models.

    PubMed

    Lee, Jaehoon; Hulse, Nathan C; Wood, Grant M; Oniki, Thomas A; Huff, Stanley M

    2016-01-01

    In this study we developed a Fast Healthcare Interoperability Resources (FHIR) profile to support exchanging a full pedigree based family health history (FHH) information across multiple systems and applications used by clinicians, patients, and researchers. We used previously developed clinical element models (CEMs) that are capable of representing the FHH information, and derived essential data elements including attributes, constraints, and value sets. We analyzed gaps between the FHH CEM elements and existing FHIR resources. Based on the analysis, we developed a profile that consists of 1) FHIR resources for essential FHH data elements, 2) extensions for additional elements that were not covered by the resources, and 3) a structured definition to integrate patient and family member information in a FHIR message. We implemented the profile using an open-source based FHIR framework and validated it using patient-entered FHH data that was captured through a locally developed FHH tool.

  6. Fast Measurement and Reconstruction of Large Workpieces with Freeform Surfaces by Combining Local Scanning and Global Position Data

    PubMed Central

    Chen, Zhe; Zhang, Fumin; Qu, Xinghua; Liang, Baoqiu

    2015-01-01

    In this paper, we propose a new approach for the measurement and reconstruction of large workpieces with freeform surfaces. The system consists of a handheld laser scanning sensor and a position sensor. The laser scanning sensor is used to acquire the surface and geometry information, and the position sensor is utilized to unify the scanning sensors into a global coordinate system. The measurement process includes data collection, multi-sensor data fusion and surface reconstruction. With the multi-sensor data fusion, errors accumulated during the image alignment and registration process are minimized, and the measuring precision is significantly improved. After the dense accurate acquisition of the three-dimensional (3-D) coordinates, the surface is reconstructed using a commercial software piece, based on the Non-Uniform Rational B-Splines (NURBS) surface. The system has been evaluated, both qualitatively and quantitatively, using reference measurements provided by a commercial laser scanning sensor. The method has been applied for the reconstruction of a large gear rim and the accuracy is up to 0.0963 mm. The results prove that this new combined method is promising for measuring and reconstructing the large-scale objects with complex surface geometry. Compared with reported methods of large-scale shape measurement, it owns high freedom in motion, high precision and high measurement speed in a wide measurement range. PMID:26091396

  7. Surface-Based Protein Binding Pocket Similarity

    PubMed Central

    Spitzer, Russell; Cleves, Ann E.; Jain, Ajay N.

    2011-01-01

    Protein similarity comparisons may be made on a local or global basis and may consider sequence information or differing levels of structural information. We present a local 3D method that compares protein binding site surfaces in full atomic detail. The approach is based on the morphological similarity method which has been widely applied for global comparison of small molecules. We apply the method to all-by-all comparisons two sets of human protein kinases, a very diverse set of ATP-bound proteins from multiple species, and three heterogeneous benchmark protein binding site data sets. Cases of disagreement between sequence-based similarity and binding site similarity yield informative examples. Where sequence similarity is very low, high pocket similarity can reliably identify important binding motifs. Where sequence similarity is very high, significant differences in pocket similarity are related to ligand binding specificity and similarity. Local protein binding pocket similarity provides qualitatively complementary information to other approaches, and it can yield quantitative information in support of functional annotation. PMID:21769944

  8. The need of MMP-2 on the sperm surface for Xenopus fertilization: its role in a fast electrical block to polyspermy.

    PubMed

    Iwao, Yasuhiro; Shiga, Keiko; Shiroshita, Ayumi; Yoshikawa, Tomoyasu; Sakiie, Maho; Ueno, Tomoyo; Ueno, Shuichi; Ijiri, Takashi W; Sato, Ken-ichi

    2014-11-01

    Monospermic fertilization in the frog, Xenopus laevis, is ensured by a fast-rising, positive fertilization potential to prevent polyspermy on the fertilized egg, followed by a slow block with the formation of a fertilization envelope over the egg surface. In this paper, we found that not only the enzymatic activity of sperm matrix metalloproteinase-2 (MMP-2) was necessary for a sperm to bind and/or pass through the extracellular coat of vitelline envelope, but also the hemopexin (HPX) domain of MMP-2 on the sperm surface was involved in binding and membrane fusion between the sperm and eggs. A peptide with a partial amino acid sequence of the HPX domain caused egg activation accompanied by an increase in [Ca(2+)]i in a voltage-dependent manner, similar to that in fertilization. The membrane microdomain (MD) of unfertilized eggs bound the HPX peptide, and this was inhibited by ganglioside GM1 distributed in the MD. The treatment of sperm with GM1 or anti-MMP-2 HPX antibody allows the sperm to fertilize an egg clamped at 0 mV, which untreated sperm cannot achieve. We propose a model accounting for the mechanism of voltage-dependent fertilization based on an interaction between the positively charged HPX domain in the sperm membrane and negatively-charged GM1 in the egg plasma membrane.

  9. Rapid determination of floral aroma compounds of lilac blossom by fast gas chromatography combined with surface acoustic wave sensor.

    PubMed

    Oh, Se Yeon; Shin, Hyun Du; Kim, Sung Jean; Hong, Jongki

    2008-03-07

    A novel analytical method using fast gas chromatography combined with surface acoustic wave sensor (GC/SAW) has been developed for the detection of volatile aroma compounds emanated from lilac blossom (Syringa species: Syringa vulgaris variginata and Syringa dilatata). GC/SAW could detect and quantify various fragrance emitted from lilac blossom, enabling to provide fragrance pattern analysis results. The fragrance pattern analysis could easily characterize the delicate differences in aromas caused by the substantial difference of chemical composition according to different color and shape of petals. Moreover, the method validation of GC/SAW was performed for the purpose of volatile floral actual aroma analysis, achieving a high reproducibility and excellent sensitivity. From the validation results, GC/SAW could serve as an alternative analytical technique for the analysis of volatile floral actual aroma of lilac. In addition, headspace solid-phase microextraction (HS-SPME) GC-MS was employed to further confirm the identification of fragrances emitted from lilac blossom and compared to GC/SAW.

  10. Distributed Function Mining for Gene Expression Programming Based on Fast Reduction

    PubMed Central

    Deng, Song; Yue, Dong; Yang, Le-chan; Fu, Xiong; Feng, Ya-zhou

    2016-01-01

    For high-dimensional and massive data sets, traditional centralized gene expression programming (GEP) or improved algorithms lead to increased run-time and decreased prediction accuracy. To solve this problem, this paper proposes a new improved algorithm called distributed function mining for gene expression programming based on fast reduction (DFMGEP-FR). In DFMGEP-FR, fast attribution reduction in binary search algorithms (FAR-BSA) is proposed to quickly find the optimal attribution set, and the function consistency replacement algorithm is given to solve integration of the local function model. Thorough comparative experiments for DFMGEP-FR, centralized GEP and the parallel gene expression programming algorithm based on simulated annealing (parallel GEPSA) are included in this paper. For the waveform, mushroom, connect-4 and musk datasets, the comparative results show that the average time-consumption of DFMGEP-FR drops by 89.09%%, 88.85%, 85.79% and 93.06%, respectively, in contrast to centralized GEP and by 12.5%, 8.42%, 9.62% and 13.75%, respectively, compared with parallel GEPSA. Six well-studied UCI test data sets demonstrate the efficiency and capability of our proposed DFMGEP-FR algorithm for distributed function mining. PMID:26751200

  11. Fast axial and lateral displacement estimation in myocardial elastography based on RF signals with predictions.

    PubMed

    Zhang, Yaonan; Sun, Tingting; Teng, Yueyang; Li, Hong; Kang, Yan

    2015-01-01

    Myocardial elastography (ME) is a strain imaging technique used to diagnose myocardial diseases. Axial and lateral displacement calculations are pre-conditions of strain image acquisition in ME. W.N. Lee et al. proposed a normalized cross-correlation (NCC) and recorrelation method to obtain both axial and lateral displacements in ME. However, this method is not noise-resistant and of high computational cost. This paper proposes a predicted fast NCC algorithm based on W.N. Lee's method, with the additions of sum-table NCC and a displacement prediction algorithm, to obtain efficient and accurate axial and lateral displacements. Compared to experiments based on the NCC and recorrelation methods, the results indicate that the proposed NCC method is much faster (predicted fast NCC method, 69.75s for a 520×260 image; NCC and recorrelation method, 1092.25s for a 520×260 image) and demonstrates better performance in eliminating decorrelation noise (SNR of the axial and lateral strain using the proposed method, 5.87 and 1.25, respectively; SNR of the axial and lateral strain using the NCC and recorrelation method, 1.48 and 1.09, respectively).

  12. Predictive-based cross line for fast motion estimation in MPEG-4 videos

    NASA Astrophysics Data System (ADS)

    Fang, Hui; Jiang, Jianmin

    2004-05-01

    Block-based motion estimation is widely used in the field of video compression due to its feature of high processing speed and competitive compression efficiency. In the chain of compression operations, however, motion estimation still remains to be the most time-consuming process. As a result, any improvement in fast motion estimation will enable practical applications of MPEG techniques more efficient and more sustainable in terms of both processing speed and computing cost. To meet the requirements of real-time compression of videos and image sequences, such as video conferencing, remote video surveillance and video phones etc., we propose a new search algorithm and achieve fast motion estimation for MPEG compression standards based on existing algorithm developments. To evaluate the proposed algorithm, we adopted MPEG-4 and the prediction line search algorithm as the benchmarks to design the experiments. Their performances are measured by: (i) reconstructed video quality; (ii) processing time. The results reveal that the proposed algorithm provides a competitive alternative to the existing prediction line search algorithm. In comparison with MPEG-4, the proposed algorithm illustrates significant advantages in terms of processing speed and video quality.

  13. Sample pretreatment and nucleic acid-based detection for fast diagnosis utilizing microfluidic systems.

    PubMed

    Wang, Jung-Hao; Wang, Chih-Hung; Lee, Gwo-Bin

    2012-06-01

    Recently, micro-electro-mechanical-systems (MEMS) technology and micromachining techniques have enabled miniaturization of biomedical devices and systems. Not only do these techniques facilitate the development of miniaturized instrumentation for biomedical analysis, but they also open a new era for integration of microdevices for performing accurate and sensitive diagnostic assays. A so-called "micro-total-analysis-system", which integrates sample pretreatment, transport, reaction, and detection on a small chip in an automatic format, can be realized by combining functional microfluidic components manufactured by specific MEMS technologies. Among the promising applications using microfluidic technologies, nucleic acid-based detection has shown considerable potential recently. For instance, micro-polymerase chain reaction chips for rapid DNA amplification have attracted considerable interest. In addition, microfluidic devices for rapid sample pretreatment prior to nucleic acid-based detection have also achieved significant progress in the recent years. In this review paper, microfluidic systems for sample preparation, nucleic acid amplification and detection for fast diagnosis will be reviewed. These microfluidic devices and systems have several advantages over their large-scale counterparts, including lower sample/reagent consumption, lower power consumption, compact size, faster analysis, and lower per unit cost. The development of these microfluidic devices and systems may provide a revolutionary platform technology for fast sample pretreatment and accurate, sensitive diagnosis.

  14. Distributed Function Mining for Gene Expression Programming Based on Fast Reduction.

    PubMed

    Deng, Song; Yue, Dong; Yang, Le-chan; Fu, Xiong; Feng, Ya-zhou

    2016-01-01

    For high-dimensional and massive data sets, traditional centralized gene expression programming (GEP) or improved algorithms lead to increased run-time and decreased prediction accuracy. To solve this problem, this paper proposes a new improved algorithm called distributed function mining for gene expression programming based on fast reduction (DFMGEP-FR). In DFMGEP-FR, fast attribution reduction in binary search algorithms (FAR-BSA) is proposed to quickly find the optimal attribution set, and the function consistency replacement algorithm is given to solve integration of the local function model. Thorough comparative experiments for DFMGEP-FR, centralized GEP and the parallel gene expression programming algorithm based on simulated annealing (parallel GEPSA) are included in this paper. For the waveform, mushroom, connect-4 and musk datasets, the comparative results show that the average time-consumption of DFMGEP-FR drops by 89.09%%, 88.85%, 85.79% and 93.06%, respectively, in contrast to centralized GEP and by 12.5%, 8.42%, 9.62% and 13.75%, respectively, compared with parallel GEPSA. Six well-studied UCI test data sets demonstrate the efficiency and capability of our proposed DFMGEP-FR algorithm for distributed function mining.

  15. Fast Electromagnetic Analysis of MRI Transmit RF Coils Based on Accelerated Integral Equation Methods.

    PubMed

    Villena, Jorge Fernandez; Polimeridis, Athanasios G; Eryaman, Yigitcan; Adalsteinsson, Elfar; Wald, Lawrence L; White, Jacob K; Daniel, Luca

    2016-11-01

    A fast frequency domain full-wave electromagnetic simulation method is introduced for the analysis of MRI coils loaded with the realistic human body models. The approach is based on integral equation methods decomposed into two domains: 1) the RF coil array and shield, and 2) the human body region where the load is placed. The analysis of multiple coil designs is accelerated by introducing the precomputed magnetic resonance Green functions (MRGFs), which describe how the particular body model used responds to the incident fields from external sources. These MRGFs, which are precomputed once for a given body model, can be combined with any integral equation solver and reused for the analysis of many coil designs. This approach provides a fast, yet comprehensive, analysis of coil designs, including the port S-parameters and the electromagnetic field distribution within the inhomogeneous body. The method solves the full-wave electromagnetic problem for a head array in few minutes, achieving a speed up of over 150 folds with root mean square errors in the electromagnetic field maps smaller than 0.4% when compared to the unaccelerated integral equation-based solver. This enables the characterization of a large number of RF coil designs in a reasonable time, which is a first step toward an automatic optimization of multiple parameters in the design of transmit arrays, as illustrated in this paper, but also receive arrays.

  16. Distributed measurement of dynamic strain based on multi-slope assisted fast BOTDA.

    PubMed

    Ba, Dexin; Wang, Benzhang; Zhou, Dengwang; Yin, Mingjing; Dong, Yongkang; Li, Hui; Lu, Zhiwei; Fan, Zhigang

    2016-05-02

    We propose and demonstrate a dynamic Brillouin optical fiber sensing based on the multi-slope assisted fast Brillouin optical time-domain analysis (F-BOTDA), which enables the measurement of a large strain with real-time data processing. The multi-slope assisted F-BOTDA is realized based on the double-slope demodulation and frequency-agile modulation, which significantly increases the measurement range compared with the single- or double- slope assisted F-BOTDA, while maintaining the advantage of fast data processing and being suitable for real-time on-line monitoring. A maximum strain variation up to 5000με is measured in a 32-m fiber with a spatial resolution of ~1m and a sampling rate of 1kHz. The frequency of the strain is 12.8Hz, which is limited by the rotation rate of the motor used to load the force on the fiber. Furthermore, the influence of the frequency difference between two adjacent probe tones on the measurement error is studied theoretically and experimentally for optimization. For a Brillouin gain spectrum with a 78-MHz width, the optimum frequency difference is ~40MHz. The measurement error of Brillouin frequency shift is less than 3MHz over the whole measurement range (241MHz).

  17. Influence of surface emission processes on a fast-pulsed dielectric barrier discharge in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Pechereau, François; Bonaventura, Zdeněk; Bourdon, Anne

    2016-08-01

    This paper presents simulations of an atmospheric pressure air discharge in a point-to-plane geometry with a dielectric layer parallel to the cathode plane. Experimentally, a discharge reignition in the air gap below the dielectrics has been observed. With a 2D fluid model, it is shown that due to the fast rise of the high voltage applied and the sharp point used, a first positive spherical discharge forms around the point. Then this discharge propagates axially and impacts the dielectrics. As the first discharge starts spreading on the upper dielectric surface, in the second air gap with a low preionization density of {{10}4}~\\text{c}{{\\text{m}}-3} , the 2D fluid model predicts a rapid reignition of a positive discharge. As in experiments, the discharge reignition is much slower, a discussion on physical processes to be considered in the model to increase the reignition delay is presented. The limit case with no initial seed charges in the second air gap has been studied. First, we have calculated the time to release an electron from the cathode surface by thermionic and field emission processes for a work function φ \\in ≤ft[3,4\\right] eV and an amplification factor β \\in ≤ft[100,220\\right] . Then a 3D Monte Carlo model has been used to follow the dynamics of formation of an avalanche starting from a single electron emitted at the cathode. Due to the high electric field in the second air gap, we have shown that in a few nanoseconds, a Gaussian cloud of seed charges is formed at a small distance from the cathode plane. This Gaussian cloud has been used as the initial condition of the 2D fluid model in the second air gap. In this case, the propagation of a double headed discharge in the second air gap has been observed and the reignition delay is in rather good agreement with experiments.

  18. Chloride-based fast homoepitaxial growth of 4H-SiC films in a vertical hot-wall CVD

    NASA Astrophysics Data System (ADS)

    Guoguo, Yan; Feng, Zhang; Yingxi, Niu; Fei, Yang; Xingfang, Liu; Lei, Wang; Wanshun, Zhao; Guosheng, Sun; Yiping, Zeng

    2016-06-01

    Chloride-based fast homoepitaxial growth of 4H-SiC epilayers was performed on 4° off-axis 4H-SiC substrates in a home-made vertical hot-wall chemical vapor deposition (CVD) system using H2-SiH4-C2H4-HCl. The effect of the SiH4/H2 ratio and reactor pressure on the growth rate of 4H-SiC epilayers has been studied successively. The growth rate increase in proportion to the SiH4/H2 ratio and the influence mechanism of chlorine has been investigated. With the reactor pressure increasing from 40 to 100 Torr, the growth rate increased to 52 μm/hand then decreased to 47 μm/h, which is due to the joint effect of H2 and HCl etching as well as the formation of Si clusters at higher reactor pressure. The surface root mean square (RMS) roughness keeps around 1 nm with the growth rate increasing to 49 μm/h. The scanning electron microscope (SEM), Raman spectroscopy and X-ray diffraction (XRD) demonstrate that 96.7 μm thick 4H-SiC layers of good uniformity in thickness and doping with high crystal quality can be achieved. These results prove that chloride-based fast epitaxy is an advanced growth technique for 4H-SiC homoepitaxy. Project supported by the National High Technology R&D Program of China (No. 2014AA041402), the National Natural Science Foundation of China (Nos. 61474113, 61274007, 61574140), the Beijing Natural Science Foundation of China (Nos. 4132076, 4132074), the Program of State Grid Smart Grid Research Institute (No. SGRI-WD-71-14-004), and the Youth Innovation Promotion Association of CAS.

  19. TH-E-BRE-08: GPU-Monte Carlo Based Fast IMRT Plan Optimization

    SciTech Connect

    Li, Y; Tian, Z; Shi, F; Jiang, S; Jia, X

    2014-06-15

    Purpose: Intensity-modulated radiation treatment (IMRT) plan optimization needs pre-calculated beamlet dose distribution. Pencil-beam or superposition/convolution type algorithms are typically used because of high computation speed. However, inaccurate beamlet dose distributions, particularly in cases with high levels of inhomogeneity, may mislead optimization, hindering the resulting plan quality. It is desire to use Monte Carlo (MC) methods for beamlet dose calculations. Yet, the long computational time from repeated dose calculations for a number of beamlets prevents this application. It is our objective to integrate a GPU-based MC dose engine in lung IMRT optimization using a novel two-steps workflow. Methods: A GPU-based MC code gDPM is used. Each particle is tagged with an index of a beamlet where the source particle is from. Deposit dose are stored separately for beamlets based on the index. Due to limited GPU memory size, a pyramid space is allocated for each beamlet, and dose outside the space is neglected. A two-steps optimization workflow is proposed for fast MC-based optimization. At first step, rough beamlet dose calculations is conducted with only a small number of particles per beamlet. Plan optimization is followed to get an approximated fluence map. In the second step, more accurate beamlet doses are calculated, where sampled number of particles for a beamlet is proportional to the intensity determined previously. A second-round optimization is conducted, yielding the final Result. Results: For a lung case with 5317 beamlets, 10{sup 5} particles per beamlet in the first round, and 10{sup 8} particles per beam in the second round are enough to get a good plan quality. The total simulation time is 96.4 sec. Conclusion: A fast GPU-based MC dose calculation method along with a novel two-step optimization workflow are developed. The high efficiency allows the use of MC for IMRT optimizations.

  20. DAN instrument for NASA`s MSL mission: fast science data processing and instrument commanding for Mars surface operations and for field tests

    NASA Astrophysics Data System (ADS)

    Vostrukhin, A.; Kozyrev, A.; Litvak, M.; Malakhov, A.; Mitrofanov, I.; Mokrousov, M.; Sanin, A.; Tretyakov, V.

    2009-04-01

    The Dynamic Albedo of Neutrons (DAN) instrument is contributed by Russian Space Agency to NASA for Mars Science Laboratory mission which was originally scheduled for 2009 and now is shifted to 2011. The design of DAN instrument is partially inherited from HEND instrument for NASA's Mars Odyssey, which now successfully operates providing global mapping of martian neutron albedo, searching the distribution of martian water and observing the martian seasonal cycles. DAN is specially designed as an active neutron instrument for surface operations onboard mobile platforms. It is able to focus science investigations on local surface area around rover with horizontal resolution about 1 meter and vertical penetration about 0.5 m. The primary goal of DAN is the exploration of the hydrogen content of the bulk Martian subsurface material. This data will be used to estimate the content of chemically bound water in the hydrated minerals. The concept of DAN operations is based on combination of neutron activation analysis and neutron well logging tequnique, which are commonly used in the Earth geological applications. DAN consists blocks of Detectors and Electronics (DE) and Pulse Neutron Generator (PNG). The last one is used to irradiate the martian subsurface by pulses of 14MeV neutrons with changeable frequency up to 10 Hz. The first one detects post-pulse afterglow of neutrons, as they were thermalized down to epithermal and thermal energies within the martian subsurface. The result of detections are so called die away curves of neutrons afterglow, which show flux and time profile of thermalized neutrons and bring to us the observational signature of layering structure of martian regolith in part of depth distribution of Hydrogen (most effective element for thermalization of neutrons). In this study we focus on the development, verification and validation of DAN fast data processing and commanding. It is necessary to perform deconvolution from counting statistic in DAN

  1. Normal adhesive contact on rough surfaces: efficient algorithm for FFT-based BEM resolution

    NASA Astrophysics Data System (ADS)

    Rey, Valentine; Anciaux, Guillaume; Molinari, Jean-François

    2017-03-01

    We introduce a numerical methodology to compute the solution of an adhesive normal contact problem on rough surfaces with the Boundary Element Method. Based on the Fast Fourier Transform and the Westergaard's fundamental solution, the proposed algorithm enables to solve efficiently the constrained minimization problem: the numerical solution strictly verifies contact orthogonality and the algorithm takes advantage of the constraints to speed up the minimization. Comparisons with the analytical solution of the Hertz case prove the quality of the numerical computation. The method is also used to compute normal adhesive contact between rough surfaces made of multiple asperities.

  2. Fast QRS Detection with an Optimized Knowledge-Based Method: Evaluation on 11 Standard ECG Databases

    PubMed Central

    Elgendi, Mohamed

    2013-01-01

    The current state-of-the-art in automatic QRS detection methods show high robustness and almost negligible error rates. In return, the methods are usually based on machine-learning approaches that require sufficient computational resources. However, simple-fast methods can also achieve high detection rates. There is a need to develop numerically efficient algorithms to accommodate the new trend towards battery-driven ECG devices and to analyze long-term recorded signals in a time-efficient manner. A typical QRS detection method has been reduced to a basic approach consisting of two moving averages that are calibrated by a knowledge base using only two parameters. In contrast to high-accuracy methods, the proposed method can be easily implemented in a digital filter design. PMID:24066054

  3. Region-based image denoising through wavelet and fast discrete curvelet transform

    NASA Astrophysics Data System (ADS)

    Gu, Yanfeng; Guo, Yan; Liu, Xing; Zhang, Ye

    2008-10-01

    Image denoising always is one of important research topics in the image processing field. In this paper, fast discrete curvelet transform (FDCT) and undecimated wavelet transform (UDWT) are proposed for image denoising. A noisy image is first denoised by FDCT and UDWT separately. The whole image space is then divided into edge region and non-edge regions. After that, wavelet transform is performed on the images denoised by FDCT and UDWT respectively. Finally, the resultant image is fused through using both of edge region wavelet cofficients of the image denoised by FDCT and non-edge region wavelet cofficients of the image denoised by UDWT. The proposed method is validated through numerical experiments conducted on standard test images. The experimental results show that the proposed algorithm outperforms wavelet-based and curvelet-based image denoising methods and preserve linear features well.

  4. Theory of ion transport with fast acid-base equilibrations in bioelectrochemical systems.

    PubMed

    Dykstra, J E; Biesheuvel, P M; Bruning, H; Ter Heijne, A

    2014-07-01

    Bioelectrochemical systems recover valuable components and energy in the form of hydrogen or electricity from aqueous organic streams. We derive a one-dimensional steady-state model for ion transport in a bioelectrochemical system, with the ions subject to diffusional and electrical forces. Since most of the ionic species can undergo acid-base reactions, ion transport is combined in our model with infinitely fast ion acid-base equilibrations. The model describes the current-induced ammonia evaporation and recovery at the cathode side of a bioelectrochemical system that runs on an organic stream containing ammonium ions. We identify that the rate of ammonia evaporation depends not only on the current but also on the flow rate of gas in the cathode chamber, the diffusion of ammonia from the cathode back into the anode chamber, through the ion exchange membrane placed in between, and the membrane charge density.

  5. A fast and low-power microelectromechanical system-based non-volatile memory device

    PubMed Central

    Lee, Sang Wook; Park, Seung Joo; Campbell, Eleanor E. B.; Park, Yung Woo

    2011-01-01

    Several new generation memory devices have been developed to overcome the low performance of conventional silicon-based flash memory. In this study, we demonstrate a novel non-volatile memory design based on the electromechanical motion of a cantilever to provide fast charging and discharging of a floating-gate electrode. The operation is demonstrated by using an electromechanical metal cantilever to charge a floating gate that controls the charge transport through a carbon nanotube field-effect transistor. The set and reset currents are unchanged after more than 11 h constant operation. Over 500 repeated programming and erasing cycles were demonstrated under atmospheric conditions at room temperature without degradation. Multinary bit programming can be achieved by varying the voltage on the cantilever. The operation speed of the device is faster than a conventional flash memory and the power consumption is lower than other memory devices. PMID:21364559

  6. Theory of ion transport with fast acid-base equilibrations in bioelectrochemical systems

    NASA Astrophysics Data System (ADS)

    Dykstra, J. E.; Biesheuvel, P. M.; Bruning, H.; Ter Heijne, A.

    2014-07-01

    Bioelectrochemical systems recover valuable components and energy in the form of hydrogen or electricity from aqueous organic streams. We derive a one-dimensional steady-state model for ion transport in a bioelectrochemical system, with the ions subject to diffusional and electrical forces. Since most of the ionic species can undergo acid-base reactions, ion transport is combined in our model with infinitely fast ion acid-base equilibrations. The model describes the current-induced ammonia evaporation and recovery at the cathode side of a bioelectrochemical system that runs on an organic stream containing ammonium ions. We identify that the rate of ammonia evaporation depends not only on the current but also on the flow rate of gas in the cathode chamber, the diffusion of ammonia from the cathode back into the anode chamber, through the ion exchange membrane placed in between, and the membrane charge density.

  7. Fast fabrication of curved microlens array using DMD-based lithography

    NASA Astrophysics Data System (ADS)

    Zhang, Zhimin; Gao, Yiqing; Luo, Ningning; Zhong, Kejun

    2016-01-01

    Curved microlens array is the core element of the biologically inspired artificial compound eye. Many existing fabrication processes remain expensive and complicated, which limits a broad range of application of the artificial compound eye. In this paper, we report a fast fabrication method for curved microlens array by using DMD-based maskless lithography. When a three-dimensional (3D) target curved profile is projected into a two-dimensional (2D) mask, arbitrary curved microlens array can be flexibly and efficiently obtained by utilizing DMD-based lithography. In order to verify the feasibility of this method, a curved PDMS microlens array with 90 micro lenslets has been fabricated. The physical and optical characteristics of the fabricated microlens array suggest that this method is potentially suitable for applications in artificial compound eye.

  8. Correlated image set compression system based on new fast efficient algorithm of Karhunen-Loeve transform

    NASA Astrophysics Data System (ADS)

    Musatenko, Yurij S.; Kurashov, Vitalij N.

    1998-10-01

    The paper presents improved version of our new method for compression of correlated image sets Optimal Image Coding using Karhunen-Loeve transform (OICKL). It is known that Karhunen-Loeve (KL) transform is most optimal representation for such a purpose. The approach is based on fact that every KL basis function gives maximum possible average contribution in every image and this contribution decreases most quickly among all possible bases. So, we lossy compress every KL basis function by Embedded Zerotree Wavelet (EZW) coding with essentially different loss that depends on the functions' contribution in the images. The paper presents new fast low memory consuming algorithm of KL basis construction for compression of correlated image ensembles that enable our OICKL system to work on common hardware. We also present procedure for determining of optimal losses of KL basic functions caused by compression. It uses modified EZW coder which produce whole PSNR (bitrate) curve during the only compression pass.

  9. Fast intensity-modulated arc therapy based on 2-step beam segmentation

    SciTech Connect

    Bratengeier, Klaus; Gainey, Mark; Sauer, Otto A.; Richter, Anne; Flentje, Michael

    2011-01-15

    Purpose: Single or few arc intensity-modulated arc therapy (IMAT) is intended to be a time saving irradiation method, potentially replacing classical intensity-modulated radiotherapy (IMRT). The aim of this work was to evaluate the quality of different IMAT methods with the potential of fast delivery, which also has the possibility of adapting to the daily shape of the target volume. Methods: A planning study was performed. Novel double and triple IMAT techniques based on the geometrical analysis of the target organ at risk geometry (2-step IMAT) were evaluated. They were compared to step and shoot IMRT reference plans generated using direct machine parameter optimization (DMPO). Volumetric arc (VMAT) plans from commercial preclinical software (SMARTARC) were used as an additional benchmark to classify the quality of the novel techniques. Four cases with concave planning target volumes (PTV) with one dominating organ at risk (OAR), viz., the PTV/OAR combination of the ESTRO Quasimodo phantom, breast/lung, spine metastasis/spinal cord, and prostate/rectum, were used for the study. The composite objective value (COV) and other parameters representing the plan quality were studied. Results: The novel 2-step IMAT techniques with geometry based segment definition were as good as or better than DMPO and were superior to the SMARTARC VMAT techniques. For the spine metastasis, the quality measured by the COV differed only by 3%, whereas the COV of the 2-step IMAT for the other three cases decreased by a factor of 1.4-2.4 with respect to the reference plans. Conclusions: Rotational techniques based on geometrical analysis of the optimization problem (2-step IMAT) provide similar or better plan quality than DMPO or the research version of SMARTARC VMAT variants. The results justify pursuing the goal of fast IMAT adaptation based on 2-step IMAT techniques.

  10. Options for a lunar base surface architecture

    NASA Technical Reports Server (NTRS)

    Roberts, Barney B.

    1992-01-01

    The Planet Surface Systems Office at the NASA Johnson Space Center has participated in an analysis of the Space Exploration Initiative architectures described in the Synthesis Group report. This effort involves a Systems Engineering and Integration effort to define point designs for evolving lunar and Mars bases that support substantial science, exploration, and resource production objectives. The analysis addresses systems-level designs; element requirements and conceptual designs; assessments of precursor and technology needs; and overall programmatics and schedules. This paper focuses on the results of the study of the Space Resource Utilization Architecture. This architecture develops the capability to extract useful materials from the indigenous resources of the Moon and Mars. On the Moon, a substantial infrastructure is emplaced which can support a crew of up to twelve. Two major process lines are developed: one produces oxygen, ceramics, and metals; the other produces hydrogen, helium, and other volatiles. The Moon is also used for a simulation of a Mars mission. Significant science capabilities are established in conjunction with resource development. Exploration includes remote global surveys and piloted sorties of local and regional areas. Science accommodations include planetary science, astronomy, and biomedical research. Greenhouses are established to provide a substantial amount of food needs.

  11. Options for a lunar base surface architecture

    NASA Astrophysics Data System (ADS)

    Roberts, Barney B.

    1992-02-01

    The Planet Surface Systems Office at the NASA Johnson Space Center has participated in an analysis of the Space Exploration Initiative architectures described in the Synthesis Group report. This effort involves a Systems Engineering and Integration effort to define point designs for evolving lunar and Mars bases that support substantial science, exploration, and resource production objectives. The analysis addresses systems-level designs; element requirements and conceptual designs; assessments of precursor and technology needs; and overall programmatics and schedules. This paper focuses on the results of the study of the Space Resource Utilization Architecture. This architecture develops the capability to extract useful materials from the indigenous resources of the Moon and Mars. On the Moon, a substantial infrastructure is emplaced which can support a crew of up to twelve. Two major process lines are developed: one produces oxygen, ceramics, and metals; the other produces hydrogen, helium, and other volatiles. The Moon is also used for a simulation of a Mars mission. Significant science capabilities are established in conjunction with resource development. Exploration includes remote global surveys and piloted sorties of local and regional areas. Science accommodations include planetary science, astronomy, and biomedical research. Greenhouses are established to provide a substantial amount of food needs.

  12. Adhesion of microchannel-based complementary surfaces.

    PubMed

    Singh, Arun K; Bai, Ying; Nadermann, Nichole; Jagota, Anand; Hui, Chung-Yuen

    2012-03-06

    We show that highly enhanced and selective adhesion can be achieved between surfaces patterned with complementary microchannel structures. An elastic material, poly(dimethylsiloxane) (PDMS), was used to fabricate such surfaces by molding into a silicon master with microchannel profiles patterned by photolithography. We carried out adhesion tests on both complementary and mismatched microchannel/micropillar surfaces. Adhesion, as measured by the energy release rate required to propagate an interfacial crack, can be enhanced by up to 40 times by complementary interfaces, compared to a flat control, and slightly enhanced for some special noncomplementary samples, despite the nearly negligible adhesion for other mismatched surfaces. For each complementary surface, we observe defects in the form of visible striations, where pillars fail to insert fully into the channels. The adhesion between complementary microchannel surfaces is enhanced by a combination of a crack-trapping mechanism and friction between a pillar and channel and is attenuated by the presence of defects.

  13. A fast Monte Carlo code for proton transport in radiation therapy based on MCNPX.

    PubMed

    Jabbari, Keyvan; Seuntjens, Jan

    2014-07-01

    An important requirement for proton therapy is a software for dose calculation. Monte Carlo is the most accurate method for dose calculation, but it is very slow. In this work, a method is developed to improve the speed of dose calculation. The method is based on pre-generated tracks for particle transport. The MCNPX code has been used for generation of tracks. A set of data including the track of the particle was produced in each particular material (water, air, lung tissue, bone, and soft tissue). This code can transport protons in wide range of energies (up to 200 MeV for proton). The validity of the fast Monte Carlo (MC) code is evaluated with data MCNPX as a reference code. While analytical pencil beam algorithm transport shows great errors (up to 10%) near small high density heterogeneities, there was less than 2% deviation of MCNPX results in our dose calculation and isodose distribution. In terms of speed, the code runs 200 times faster than MCNPX. In the Fast MC code which is developed in this work, it takes the system less than 2 minutes to calculate dose for 10(6) particles in an Intel Core 2 Duo 2.66 GHZ desktop computer.

  14. A fast Monte Carlo code for proton transport in radiation therapy based on MCNPX

    PubMed Central

    Jabbari, Keyvan; Seuntjens, Jan

    2014-01-01

    An important requirement for proton therapy is a software for dose calculation. Monte Carlo is the most accurate method for dose calculation, but it is very slow. In this work, a method is developed to improve the speed of dose calculation. The method is based on pre-generated tracks for particle transport. The MCNPX code has been used for generation of tracks. A set of data including the track of the particle was produced in each particular material (water, air, lung tissue, bone, and soft tissue). This code can transport protons in wide range of energies (up to 200 MeV for proton). The validity of the fast Monte Carlo (MC) code is evaluated with data MCNPX as a reference code. While analytical pencil beam algorithm transport shows great errors (up to 10%) near small high density heterogeneities, there was less than 2% deviation of MCNPX results in our dose calculation and isodose distribution. In terms of speed, the code runs 200 times faster than MCNPX. In the Fast MC code which is developed in this work, it takes the system less than 2 minutes to calculate dose for 106 particles in an Intel Core 2 Duo 2.66 GHZ desktop computer. PMID:25190994

  15. Fast template matching based on grey prediction for real-time object tracking

    NASA Astrophysics Data System (ADS)

    Lv, Mingming; Hou, Yuanlong; Liu, Rongzhong; Hou, Runmin

    2017-02-01

    Template matching is a basic algorithm for image processing, and real-time is a crucial requirement of object tracking. For real-time tracking, a fast template matching algorithm based on grey prediction is presented, where computation cost can be reduced dramatically by minimizing search range. First, location of the tracked object in the current image is estimated by Grey Model (GM). GM(1,1), which is the basic model of grey prediction, can use some known information to foretell the location. Second, the precise position of the object in the frame is computed by template matching. Herein, Sequential Similarity Detection Algorithm (SSDA) with a self-adaptive threshold is employed to obtain the matching position in the neighborhood of the predicted location. The role of threshold in SSDA is important, as a proper threshold can make template matching fast and accurate. Moreover, a practical weighted strategy is utilized to handle scale and rotation changes of the object, as well as illumination changes. The experimental results show the superior performance of the proposed algorithm over the conventional full-search method, especially in terms of executive time.

  16. Understanding and eliminating the fast creep problem in Fe-based superconductors

    NASA Astrophysics Data System (ADS)

    Civale, Leonardo; Eley, Serena; Maiorov, Boris; Miura, Masashi

    One surprising characteristic of Fe-based superconductors is that they exhibit flux creep rates (S) as large as, or larger than, those found in oxide high temperature superconductors (HTS). This very fast vortex dynamics appears to be inconsistent with the estimate of the influence of the thermal fluctuations as quantified by the Ginzburg number (Gi), which measures the ratio of the thermal energy to the condensation energy in an elemental superconducting volume. In particular, compounds of the AFe2As2 family (``122'') have Gi ~10-5 to 10-4, so S could be expected to lie between that of low Tc materials (where typically Gi ~ 10-8) and HTS such as YBa2Cu3O7 (Gi ~ 10-2) , as indeed occurs in other superconductors with intermediate fluctuations, such as MgB2 (Gi ~10-6 to 10-4) . We have found the solution to this puzzle: the fast creep rates in 122 compounds are due to non-optimized pinning landscapes. Initial evidence comes from our previous studies showing that the introduction of additional disorder by irradiation decreases creep significantly in 122 single crystals, although still remaining well above the ideal limit. We now have new evidence from 122 thin films demonstrating that S can be reduced to the lower limit set by Gi by appropriate engineering of the pinning landscape.

  17. Fast single photon avalanche photodiode-based time-resolved diffuse optical tomography scanner

    PubMed Central

    Mu, Ying; Niedre, Mark

    2015-01-01

    Resolution in diffuse optical tomography (DOT) is a persistent problem and is primarily limited by high degree of light scatter in biological tissue. We showed previously that the reduction in photon scatter between a source and detector pair at early time points following a laser pulse in time-resolved DOT is highly dependent on the temporal response of the instrument. To this end, we developed a new single-photon avalanche photodiode (SPAD) based time-resolved DOT scanner. This instrument uses an array of fast SPADs, a femto-second Titanium Sapphire laser and single photon counting electronics. In combination, the overall instrument temporal impulse response function width was 59 ps. In this paper, we report the design of this instrument and validate its operation in symmetrical and irregularly shaped optical phantoms of approximately small animal size. We were able to accurately reconstruct the size and position of up to 4 absorbing inclusions, with increasing image quality at earlier time windows. We attribute these results primarily to the rapid response time of our instrument. These data illustrate the potential utility of fast SPAD detectors in time-resolved DOT. PMID:26417526

  18. Cygrid: A fast Cython-powered convolution-based gridding module for Python

    NASA Astrophysics Data System (ADS)

    Winkel, B.; Lenz, D.; Flöer, L.

    2016-06-01

    Context. Data gridding is a common task in astronomy and many other science disciplines. It refers to the resampling of irregularly sampled data to a regular grid. Aims: We present cygrid, a library module for the general purpose programming language Python. Cygrid can be used to resample data to any collection of target coordinates, although its typical application involves FITS maps or data cubes. The FITS world coordinate system standard is supported. Methods: The regridding algorithm is based on the convolution of the original samples with a kernel of arbitrary shape. We introduce a lookup table scheme that allows us to parallelize the gridding and combine it with the HEALPix tessellation of the sphere for fast neighbor searches. Results: We show that for n input data points, cygrids runtime scales between O(n) and O(nlog n) and analyze the performance gain that is achieved using multiple CPU cores. We also compare the gridding speed with other techniques, such as nearest-neighbor, and linear and cubic spline interpolation. Conclusions: Cygrid is a very fast and versatile gridding library that significantly outperforms other third-party Python modules, such as the linear and cubic spline interpolation provided by SciPy. http://https://github.com/bwinkel/cygrid

  19. Fast multichannel astronomical photometer based on silicon photo multipliers mounted at the Telescopio Nazionale Galileo

    NASA Astrophysics Data System (ADS)

    Ambrosino, Filippo; Meddi, Franco; Rossi, Corinne; Sclavi, Silvia; Nesci, Roberto; Bruni, Ivan; Ghedina, Adriano; Riverol, Luis; Di Fabrizio, Luca

    2014-07-01

    The realization of low-cost instruments with high technical performance is a goal that deserves efforts in an epoch of fast technological developments. Such instruments can be easily reproduced and therefore allow new research programs to be opened in several observatories. We realized a fast optical photometer based on the SiPM (Silicon Photo Multiplier) technology, using commercially available modules. Using low-cost components, we developed a custom electronic chain to extract the signal produced by a commercial MPPC (Multi Pixel Photon Counter) module produced by Hamamatsu Photonics to obtain sub-millisecond sampling of the light curve of astronomical sources (typically pulsars). We built a compact mechanical interface to mount the MPPC at the focal plane of the TNG (Telescopio Nazionale Galileo), using the space available for the slits of the LRS (Low Resolution Spectrograph). On February 2014 we observed the Crab pulsar with the TNG with our prototype photometer, deriving its period and the shape of its light curve, in very good agreement with the results obtained in the past with other much more expensive instruments. After the successful run at the telescope we describe here the lessons learned and the ideas that burst to optimize this instrument and make it more versatile.

  20. A fast continuous magnetic field measurement system based on digital signal processors

    SciTech Connect

    Velev, G.V.; Carcagno, R.; DiMarco, J.; Kotelnikov, S.; Lamm, M.; Makulski, A.; Maroussov, V.; Nehring, R.; Nogiec, J.; Orris, D.; Poukhov, O.; Prakoshyn, F.; Schlabach, P.; Tompkins, J.C.; /Fermilab

    2005-09-01

    In order to study dynamic effects in accelerator magnets, such as the decay of the magnetic field during the dwell at injection and the rapid so-called ''snapback'' during the first few seconds of the resumption of the energy ramp, a fast continuous harmonics measurement system was required. A new magnetic field measurement system, based on the use of digital signal processors (DSP) and Analog to Digital (A/D) converters, was developed and prototyped at Fermilab. This system uses Pentek 6102 16 bit A/D converters and the Pentek 4288 DSP board with the SHARC ADSP-2106 family digital signal processor. It was designed to acquire multiple channels of data with a wide dynamic range of input signals, which are typically generated by a rotating coil probe. Data acquisition is performed under a RTOS, whereas processing and visualization are performed under a host computer. Firmware code was developed for the DSP to perform fast continuous readout of the A/D FIFO memory and integration over specified intervals, synchronized to the probe's rotation in the magnetic field. C, C++ and Java code was written to control the data acquisition devices and to process a continuous stream of data. The paper summarizes the characteristics of the system and presents the results of initial tests and measurements.

  1. Autonomous celestial navigation based on Earth ultraviolet radiance and fast gradient statistic feature extraction

    NASA Astrophysics Data System (ADS)

    Lu, Shan; Zhang, Hanmo

    2016-01-01

    To meet the requirement of autonomous orbit determination, this paper proposes a fast curve fitting method based on earth ultraviolet features to obtain accurate earth vector direction, in order to achieve the high precision autonomous navigation. Firstly, combining the stable characters of earth ultraviolet radiance and the use of transmission model software of atmospheric radiation, the paper simulates earth ultraviolet radiation model on different time and chooses the proper observation band. Then the fast improved edge extracting method combined Sobel operator and local binary pattern (LBP) is utilized, which can both eliminate noises efficiently and extract earth ultraviolet limb features accurately. And earth's centroid locations on simulated images are estimated via the least square fitting method using part of the limb edges. Taken advantage of the estimated earth vector direction and earth distance, Extended Kalman Filter (EKF) is applied to realize the autonomous navigation finally. Experiment results indicate the proposed method can achieve a sub-pixel earth centroid location estimation and extremely enhance autonomous celestial navigation precision.

  2. Beam test results of a 16 ps timing system based on ultra-fast silicon detectors

    NASA Astrophysics Data System (ADS)

    Cartiglia, N.; Staiano, A.; Sola, V.; Arcidiacono, R.; Cirio, R.; Cenna, F.; Ferrero, M.; Monaco, V.; Mulargia, R.; Obertino, M.; Ravera, F.; Sacchi, R.; Bellora, A.; Durando, S.; Mandurrino, M.; Minafra, N.; Fadeyev, V.; Freeman, P.; Galloway, Z.; Gkougkousis, E.; Grabas, H.; Gruey, B.; Labitan, C. A.; Losakul, R.; Luce, Z.; McKinney-Martinez, F.; Sadrozinski, H. F.-W.; Seiden, A.; Spencer, E.; Wilder, M.; Woods, N.; Zatserklyaniy, A.; Pellegrini, G.; Hidalgo, S.; Carulla, M.; Flores, D.; Merlos, A.; Quirion, D.; Cindro, V.; Kramberger, G.; Mandić, I.; Mikuž, M.; Zavrtanik, M.

    2017-04-01

    In this paper we report on the timing resolution obtained in a beam test with pions of 180 GeV/c momentum at CERN for the first production of 45 μm thick Ultra-Fast Silicon Detectors (UFSD). UFSD are based on the Low-Gain Avalanche Detector (LGAD) design, employing n-on-p silicon sensors with internal charge multiplication due to the presence of a thin, low-resistivity diffusion layer below the junction. The UFSD used in this test had a pad area of 1.7 mm2. The gain was measured to vary between 5 and 70 depending on the sensor bias voltage. The experimental setup included three UFSD and a fast trigger consisting of a quartz bar readout by a SiPM. The timing resolution was determined by doing Gaussian fits to the time-of-flight of the particles between one or more UFSD and the trigger counter. For a single UFSD the resolution was measured to be 34 ps for a bias voltage of 200 V, and 27 ps for a bias voltage of 230 V. For the combination of 3 UFSD the timing resolution was 20 ps for a bias voltage of 200 V, and 16 ps for a bias voltage of 230 V.

  3. Fast Coalescent-Based Computation of Local Branch Support from Quartet Frequencies

    PubMed Central

    Sayyari, Erfan; Mirarab, Siavash

    2016-01-01

    Species tree reconstruction is complicated by effects of incomplete lineage sorting, commonly modeled by the multi-species coalescent model (MSC). While there has been substantial progress in developing methods that estimate a species tree given a collection of gene trees, less attention has been paid to fast and accurate methods of quantifying support. In this article, we propose a fast algorithm to compute quartet-based support for each branch of a given species tree with regard to a given set of gene trees. We then show how the quartet support can be used in the context of the MSC to compute (1) the local posterior probability (PP) that the branch is in the species tree and (2) the length of the branch in coalescent units. We evaluate the precision and recall of the local PP on a wide set of simulated and biological datasets, and show that it has very high precision and improved recall compared with multi-locus bootstrapping. The estimated branch lengths are highly accurate when gene tree estimation error is low, but are underestimated when gene tree estimation error increases. Computation of both the branch length and local PP is implemented as new features in ASTRAL. PMID:27189547

  4. Multirate-based fast parallel algorithms for 2-D DHT-based real-valued discrete Gabor transform.

    PubMed

    Tao, Liang; Kwan, Hon Keung

    2012-07-01

    Novel algorithms for the multirate and fast parallel implementation of the 2-D discrete Hartley transform (DHT)-based real-valued discrete Gabor transform (RDGT) and its inverse transform are presented in this paper. A 2-D multirate-based analysis convolver bank is designed for the 2-D RDGT, and a 2-D multirate-based synthesis convolver bank is designed for the 2-D inverse RDGT. The parallel channels in each of the two convolver banks have a unified structure and can apply the 2-D fast DHT algorithm to speed up their computations. The computational complexity of each parallel channel is low and is independent of the Gabor oversampling rate. All the 2-D RDGT coefficients of an image are computed in parallel during the analysis process and can be reconstructed in parallel during the synthesis process. The computational complexity and time of the proposed parallel algorithms are analyzed and compared with those of the existing fastest algorithms for 2-D discrete Gabor transforms. The results indicate that the proposed algorithms are the fastest, which make them attractive for real-time image processing.

  5. A fast density-based clustering algorithm for real-time Internet of Things stream.

    PubMed

    Amini, Amineh; Saboohi, Hadi; Wah, Teh Ying; Herawan, Tutut

    2014-01-01

    Data streams are continuously generated over time from Internet of Things (IoT) devices. The faster all of this data is analyzed, its hidden trends and patterns discovered, and new strategies created, the faster action can be taken, creating greater value for organizations. Density-based method is a prominent class in clustering data streams. It has the ability to detect arbitrary shape clusters, to handle outlier, and it does not need the number of clusters in advance. Therefore, density-based clustering algorithm is a proper choice for clustering IoT streams. Recently, several density-based algorithms have been proposed for clustering data streams. However, density-based clustering in limited time is still a challenging issue. In this paper, we propose a density-based clustering algorithm for IoT streams. The method has fast processing time to be applicable in real-time application of IoT devices. Experimental results show that the proposed approach obtains high quality results with low computation time on real and synthetic datasets.

  6. An optimized fast image resizing method based on content-aware

    NASA Astrophysics Data System (ADS)

    Lu, Yan; Gao, Kun; Wang, Kewang; Xu, Tingfa

    2014-11-01

    In traditional image resizing theory based on interpolation, the prominent object may cause distortion, and the image resizing method based on content-aware has become a research focus in image processing because the prominent content and structural features of images are considered in this method. In this paper, we present an optimized fast image resizing method based on content-aware. Firstly, an appropriate energy function model is constructed on the basis of image meshes, and multiple energy constraint templates are established. In addition, this paper deducts the image saliency constraints, and then the problem of image resizing is used to reformulate a kind of convex quadratic program task. Secondly, a method based on neural network is presented in solving the problem of convex quadratic program. The corresponding neural network model is constructed; moreover, some sufficient conditions of the neural network stability are given. Compared with the traditional numerical algorithm such as iterative method, the neural network method is essentially parallel and distributed, which can expedite the calculation speed. Finally, the effects of image resizing by the proposed method and traditional image resizing method based on interpolation are compared by adopting MATLAB software. Experiment results show that this method has a higher performance of identifying the prominent object, and the prominent features can be preserved effectively after the image is resized. It also has the advantages of high portability and good real-time performance with low visual distortion.

  7. PCM-Based Durable Write Cache for Fast Disk I/O

    SciTech Connect

    Liu, Zhuo; Wang, Bin; Carpenter, Patrick; Li, Dong; Vetter, Jeffrey S; Yu, Weikuan

    2012-01-01

    Flash based solid-state devices (FSSDs) have been adopted within the memory hierarchy to improve the performance of hard disk drive (HDD) based storage system. However, with the fast development of storage-class memories, new storage technologies with better performance and higher write endurance than FSSDs are emerging, e.g., phase-change memory (PCM). Understanding how to leverage these state-of-the-art storage technologies for modern computing systems is important to solve challenging data intensive computing problems. In this paper, we propose to leverage PCM for a hybrid PCM-HDD storage architecture. We identify the limitations of traditional LRU caching algorithms for PCM-based caches, and develop a novel hash-based write caching scheme called HALO to improve random write performance of hard disks. To address the limited durability of PCM devices and solve the degraded spatial locality in traditional wear-leveling techniques, we further propose novel PCM management algorithms that provide effective wear-leveling while maximizing access parallelism. We have evaluated this PCM-based hybrid storage architecture using applications with a diverse set of I/O access patterns. Our experimental results demonstrate that the HALO caching scheme leads to an average reduction of 36.8% in execution time compared to the LRU caching scheme, and that the SFC wear leveling extends the lifetime of PCM by a factor of 21.6.

  8. Project FAST.

    ERIC Educational Resources Information Center

    Essexville-Hampton Public Schools, MI.

    Described are components of Project FAST (Functional Analysis Systems Training) a nationally validated project to provide more effective educational and support services to learning disordered children and their regular elementary classroom teachers. The program is seen to be based on a series of modules of delivery systems ranging from mainstream…

  9. Global convergence analysis of fast multiobjective gradient-based dose optimization algorithms for high-dose-rate brachytherapy.

    PubMed

    Lahanas, M; Baltas, D; Giannouli, S

    2003-03-07

    We consider the problem of the global convergence of gradient-based optimization algorithms for interstitial high-dose-rate (HDR) brachytherapy dose optimization using variance-based objectives. Possible local minima could lead to only sub-optimal solutions. We perform a configuration space analysis using a representative set of the entire non-dominated solution space. A set of three prostate implants is used in this study. We compare the results obtained by conjugate gradient algorithms, two variable metric algorithms and fast-simulated annealing. For the variable metric algorithm BFGS from numerical recipes, large fluctuations are observed. The limited memory L-BFGS algorithm and the conjugate gradient algorithm FRPR are globally convergent. Local minima or degenerate states are not observed. We study the possibility of obtaining a representative set of non-dominated solutions using optimal solution rearrangement and a warm start mechanism. For the surface and volume dose variance and their derivatives, a method is proposed which significantly reduces the number of required operations. The optimization time, ignoring a preprocessing step, is independent of the number of sampling points in the planning target volume. Multiobjective dose optimization in HDR brachytherapy using L-BFGS and a new modified computation method for the objectives and derivatives has been accelerated, depending on the number of sampling points, by a factor in the range 10-100.

  10. Impact of Using a High Surface Area Solid Phase Micro Extraction Device and Fast Gas Chromatography Heating Rates in the Sampling and Analysis of Trace Level Chemical Warfare Agents and CWA-Like Compounds

    DTIC Science & Technology

    2009-09-21

    MICROEXTRACTION DEVICE AND FAST GAS CHROMATOGRAPHY HEATING RATES IN THE SAMPLING AND ANALYSIS OF TRACE LEVEL CHEMICAL WARFARE AGENTS AND CWA-LIKE...v “IMPACT OF USING A HIGH SURFACE AREA SOLID PHASE MICROEXTRACTION DEVICE AND FAST GAS CHROMATOGRAPHY HEATING RATES IN THE SAMPLING AND...10 CHAPTER 3. APPLICATION OF A HIGH SURFACE AREA SOLID PHASE MICROEXTRACTION AIR SAMPLING DEVICE FOR

  11. Fault Diagnosis of Rolling Bearing Based on Fast Nonlocal Means and Envelop Spectrum

    PubMed Central

    Lv, Yong; Zhu, Qinglin; Yuan, Rui

    2015-01-01

    The nonlocal means (NL-Means) method that has been widely used in the field of image processing in recent years effectively overcomes the limitations of the neighborhood filter and eliminates the artifact and edge problems caused by the traditional image denoising methods. Although NL-Means is very popular in the field of 2D image signal processing, it has not received enough attention in the field of 1D signal processing. This paper proposes a novel approach that diagnoses the fault of a rolling bearing based on fast NL-Means and the envelop spectrum. The parameters of the rolling bearing signals are optimized in the proposed method, which is the key contribution of this paper. This approach is applied to the fault diagnosis of rolling bearing, and the results have shown the efficiency at detecting roller bearing failures. PMID:25585105

  12. Fast depth decision for HEVC inter prediction based on spatial and temporal correlation

    NASA Astrophysics Data System (ADS)

    Chen, Gaoxing; Liu, Zhenyu; Ikenaga, Takeshi

    2016-07-01

    High efficiency video coding (HEVC) is a video compression standard that outperforms the predecessor H.264/AVC by doubling the compression efficiency. To enhance the compression accuracy, the partition sizes ranging is from 4x4 to 64x64 in HEVC. However, the manifold partition sizes dramatically increase the encoding complexity. This paper proposes a fast depth decision based on spatial and temporal correlation. Spatial correlation utilize the code tree unit (CTU) Splitting information and temporal correlation utilize the motion vector predictor represented CTU in inter prediction to determine the maximum depth in each CTU. Experimental results show that the proposed method saves about 29.1% of the original processing time with 0.9% of BD-bitrate increase on average.

  13. A fast and accurate image-based measuring system for isotropic reflection materials

    NASA Astrophysics Data System (ADS)

    Kim, Duck Bong; Kim, Kang Yeon; Park, Kang Su; Seo, Myoung Kook; Lee, Kwan H.

    2008-08-01

    We present a novel image-based BRDF (Bidirectional Reflectance Distribution Function) measurement system for materials that have isotropic reflectance properties. Our proposed system is fast due to simple set up and automated operations. It also provides a wide angular coverage and noise reduction capability so that it achieves accuracy that is needed for computer graphics applications. We test the uniformity and constancy of the light source and the reciprocity of the measurement system. We perform a photometric calibration of HDR (High Dynamic Range) camera to recover an accurate radiance map from each HDR image. We verify our proposed system by comparing it with a previous imagebased BRDF measurement system. We demonstrate the efficiency and accuracy of our proposed system by generating photorealistic images of the measured BRDF data that include glossy blue, green plastics, gold coated metal and gold metallic paints.

  14. Fast approach to infrared image restoration based on shrinkage functions calibration

    NASA Astrophysics Data System (ADS)

    Zhang, Chengshuo; Shi, Zelin; Xu, Baoshu; Feng, Bin

    2016-05-01

    High-quality image restoration in real time is a challenge for infrared imaging systems. We present a fast approach to infrared image restoration based on shrinkage functions calibration. Rather than directly modeling the prior of sharp images to obtain the shrinkage functions, we calibrate them for restoration directly by using the acquirable sharp and blurred image pairs from the same infrared imaging system. The calibration method is employed to minimize the sum of squared errors between sharp images and restored images from the blurred images. Our restoration algorithm is noniterative and its shrinkage functions are stored in the look-up tables, so an architecture solution of pipeline structure can work in real time. We demonstrate the effectiveness of our approach by testing its quantitative performance from simulation experiments and its qualitative performance from a developed wavefront coding infrared imaging system.

  15. A robust and fast line segment detector based on top-down smaller eigenvalue analysis

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Wang, Yongtao; Tang, Zhi; Lu, Xiaoqing

    2014-01-01

    In this paper, we propose a robust and fast line segment detector, which achieves accurate results with a controlled number of false detections and requires no parameter tuning. It consists of three steps: first, we propose a novel edge point chaining method to extract Canny edge segments (i.e., contiguous chains of Canny edge points) from the input image; second, we propose a top-down scheme based on smaller eigenvalue analysis to extract line segments within each obtained edge segment; third, we employ Desolneux et al.'s method to reject false detections. Experiments demonstrate that it is very efficient and more robust than two state of the art methods—LSD and EDLines.

  16. Proton linac for hospital-based fast neutron therapy and radioisotope production

    SciTech Connect

    Lennox, A.J.; Hendrickson, F.R.; Swenson, D.A.; Winje, R.A.; Young, D.E.; Rush Univ., Chicago, IL; Science Applications International Corp., Princeton, NJ; Fermi National Accelerator Lab., Batavia, IL )

    1989-09-01

    Recent developments in linac technology have led to the design of a hospital-based proton linac for fast neutron therapy. The 180 microamp average current allows beam to be diverted for radioisotope production during treatments while maintaining an acceptable dose rate. During dedicated operation, dose rates greater than 280 neutron rads per minute are achievable at depth, DMAX = 1.6 cm with source to axis distance, SAD = 190 cm. Maximum machine energy is 70 MeV and several intermediate energies are available for optimizing production of isotopes for Positron Emission Tomography and other medical applications. The linac can be used to produce a horizontal or a gantry can be added to the downstream end of the linac for conventional patient positioning. The 70 MeV protons can also be used for proton therapy for ocular melanomas. 17 refs., 1 fig., 1 tab.

  17. Analysis of Nickel Based Hardfacing Materials Manufactured by Laser Cladding for Sodium Fast Reactor

    NASA Astrophysics Data System (ADS)

    Aubry, P.; Blanc, C.; Demirci, I.; Dal, M.; Malot, T.; Maskrot, H.

    For improving the operational capacity, the maintenance and the decommissioning of the future French Sodium Fast Reactor ASTRID which is under study, it is asked to find or develop a cobalt free hardfacing alloy and the associated manufacturing process that will give satisfying wear performances. This article presents recent results obtained on some selected nickel-based hardfacing alloys manufactured by laser cladding, particularly on Tribaloy 700 alloy. A process parameter search is made and associated the microstructural analysis of the resulting clads. A particular attention is made on the solidification of the main precipitates (chromium carbides, boron carbides, Laves phases,…) that will mainly contribute to the wear properties of the material. Finally, the wear resistance of some samples is evaluated in simple wear conditions evidencing promising results on tribology behavior of Tribaloy 700.

  18. Two-dimensional electronic spectroscopy based on conventional optics and fast dual chopper data acquisition

    NASA Astrophysics Data System (ADS)

    Heisler, Ismael A.; Moca, Roberta; Camargo, Franco V. A.; Meech, Stephen R.

    2014-06-01

    We report an improved experimental scheme for two-dimensional electronic spectroscopy (2D-ES) based solely on conventional optical components and fast data acquisition. This is accomplished by working with two choppers synchronized to a 10 kHz repetition rate amplified laser system. We demonstrate how scattering and pump-probe contributions can be removed during 2D measurements and how the pump probe and local oscillator spectra can be generated and saved simultaneously with each population time measurement. As an example the 2D-ES spectra for cresyl violet were obtained. The resulting 2D spectra show a significant oscillating signal during population evolution time which can be assigned to an intramolecular vibrational mode.

  19. A fast image retrieval method based on SVM and imbalanced samples in filtering multimedia message spam

    NASA Astrophysics Data System (ADS)

    Chen, Zhang; Peng, Zhenming; Peng, Lingbing; Liao, Dongyi; He, Xin

    2011-11-01

    With the swift and violent development of the Multimedia Messaging Service (MMS), it becomes an urgent task to filter the Multimedia Message (MM) spam effectively in real-time. For the fact that most MMs contain images or videos, a method based on retrieving images is given in this paper for filtering MM spam. The detection method used in this paper is a combination of skin-color detection, texture detection, and face detection, and the classifier for this imbalanced problem is a very fast multi-classification combining Support vector machine (SVM) with unilateral binary decision tree. The experiments on 3 test sets show that the proposed method is effective, with the interception rate up to 60% and the average detection time for each image less than 1 second.

  20. A fast and scalable content transfer protocol (FSCTP) for VANET based architecture

    NASA Astrophysics Data System (ADS)

    Santamaria, A. F.; Scala, F.; Sottile, C.; Tropea, M.; Raimondo, P.

    2016-05-01

    In the modern Vehicular Ad-hoc Networks (VANET) based systems even more applications require lot of data to be exchanged among vehicles and infrastructure entities. Due to mobility issues and unplanned events that may occurs it is important that contents should be transferred as fast as possible by taking into account consistence of the exchanged data and reliability of the connections. In order to face with these issues, in this work we propose a new transfer data protocol called Fast and Scalable Content Transfer Protocol (FSCTP). This protocol allows a data transfer by using a bidirectional channel among content suppliers and receivers exploiting several cooperative sessions. Each session will be based on User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) to start and manage data transfer. Often in urban area the VANET scenario is composed of several vehicle and infrastructures points. The main idea is to exploit ad-hoc connections between vehicles to reach content suppliers. Moreover, in order to obtain a faster data transfer, more than one session is exploited to achieve a higher transfer rate. Of course it is important to manage data transfer between suppliers to avoid redundancy and resource wastages. The main goal is to instantiate a cooperative multi-session layer efficiently managed in a VANET environment exploiting the wide coverage area and avoiding common issues known in this kind of scenario. High mobility and unstable connections between nodes are some of the most common issues to address, thus a cooperative work between network, transport and application layers needs to be designed.

  1. CRBLASTER: A Fast Parallel-Processing Program for Cosmic Ray Rejection in Space-Based Observations

    NASA Astrophysics Data System (ADS)

    Mighell, K.

    Many astronomical image analysis tasks are based on algorithms that can be described as being embarrassingly parallel - where the analysis of one subimage generally does not affect the analysis of another subimage. Yet few parallel-processing astrophysical image-analysis programs exist that can easily take full advantage of today's fast multi-core servers costing a few thousands of dollars. One reason for the shortage of state-of-the-art parallel processing astrophysical image-analysis codes is that the writing of parallel codes has been perceived to be difficult. I describe a new fast parallel-processing image-analysis program called CRBLASTER which does cosmic ray rejection using van Dokkum's L.A.Cosmic algorithm. CRBLASTER is written in C using the industry standard Message Passing Interface library. Processing a single 800 x 800 Hubble Space Telescope Wide-Field Planetary Camera 2 (WFPC2) image takes 1.9 seconds using 4 processors on an Apple Xserve with two dual-core 3.0-GHz Intel Xeons; the efficiency of the program running with the 4 cores is 82%. The code has been designed to be used as a software framework for the easy development of parallel-processing image-analysis programs using embarrassing parallel algorithms; all that needs to be done is to replace the core image processing task (in this case the C function that performs the L.A.Cosmic algorithm) with an alternative image analysis task based on a single processor algorithm. I describe the design and implementation of the program and then discuss how it could possibly be used to quickly do time-critical analysis applications such as those involved with space surveillance or do complex calibration tasks as part of the pipeline processing of images from large focal plane arrays.

  2. Fast GPU-based absolute intensity determination for energy-dispersive X-ray Laue diffraction

    NASA Astrophysics Data System (ADS)

    Alghabi, F.; Send, S.; Schipper, U.; Abboud, A.; Pietsch, U.; Kolb, A.

    2016-01-01

    This paper presents a novel method for fast determination of absolute intensities in the sites of Laue spots generated by a tetragonal hen egg-white lysozyme crystal after exposure to white synchrotron radiation during an energy-dispersive X-ray Laue diffraction experiment. The Laue spots are taken by means of an energy-dispersive X-ray 2D pnCCD detector. Current pnCCD detectors have a spatial resolution of 384 × 384 pixels of size 75 × 75 μm2 each and operate at a maximum of 400 Hz. Future devices are going to have higher spatial resolution and frame rates. The proposed method runs on a computer equipped with multiple Graphics Processing Units (GPUs) which provide fast and parallel processing capabilities. Accordingly, our GPU-based algorithm exploits these capabilities to further analyse the Laue spots of the sample. The main contribution of the paper is therefore an alternative algorithm for determining absolute intensities of Laue spots which are themselves computed from a sequence of pnCCD frames. Moreover, a new method for integrating spectral peak intensities and improved background correction, a different way of calculating mean count rate of the background signal and also a new method for n-dimensional Poisson fitting are presented.We present a comparison of the quality of results from the GPU-based algorithm with the quality of results from a prior (base) algorithm running on CPU. This comparison shows that our algorithm is able to produce results with at least the same quality as the base algorithm. Furthermore, the GPU-based algorithm is able to speed up one of the most time-consuming parts of the base algorithm, which is n-dimensional Poisson fitting, by a factor of more than 3. Also, the entire procedure of extracting Laue spots' positions, energies and absolute intensities from a raw dataset of pnCCD frames is accelerated by a factor of more than 3.

  3. Compressive sensing for seismic data reconstruction via fast projection onto convex sets based on seislet transform

    NASA Astrophysics Data System (ADS)

    Gan, Shuwei; Wang, Shoudong; Chen, Yangkang; Chen, Xiaohong; Huang, Weiling; Chen, Hanming

    2016-07-01

    According to the compressive sensing (CS) theory in the signal-processing field, we proposed a new CS approach based on a fast projection onto convex sets (POCS) algorithm with sparsity constraint in the seislet transform domain. The seislet transform appears to be the sparest among the state-of-the-art sparse transforms. The FPOCS can obtain much faster convergence than conventional POCS (about two thirds of conventional iterations can be saved), while maintaining the same recovery performance. The FPOCS can obtain faster and better performance than FISTA for relatively cleaner data but will get slower and worse performance than FISTA, which becomes a reference to decide which algorithm to use in practice according the noise level in the seismic data. The seislet transform based CS approach can achieve obviously better data recovery results than f - k transform based scenarios, considering both signal-to-noise ratio (SNR), local similarity comparison, and visual observation, because of a much sparser structure in the seislet transform domain. We have used both synthetic and field data examples to demonstrate the superior performance of the proposed seislet-based FPOCS approach.

  4. PRIMAL: Fast and accurate pedigree-based imputation from sequence data in a founder population.

    PubMed

    Livne, Oren E; Han, Lide; Alkorta-Aranburu, Gorka; Wentworth-Sheilds, William; Abney, Mark; Ober, Carole; Nicolae, Dan L

    2015-03-01

    Founder populations and large pedigrees offer many well-known advantages for genetic mapping studies, including cost-efficient study designs. Here, we describe PRIMAL (PedigRee IMputation ALgorithm), a fast and accurate pedigree-based phasing and imputation algorithm for founder populations. PRIMAL incorporates both existing and original ideas, such as a novel indexing strategy of Identity-By-Descent (IBD) segments based on clique graphs. We were able to impute the genomes of 1,317 South Dakota Hutterites, who had genome-wide genotypes for ~300,000 common single nucleotide variants (SNVs), from 98 whole genome sequences. Using a combination of pedigree-based and LD-based imputation, we were able to assign 87% of genotypes with >99% accuracy over the full range of allele frequencies. Using the IBD cliques we were also able to infer the parental origin of 83% of alleles, and genotypes of deceased recent ancestors for whom no genotype information was available. This imputed data set will enable us to better study the relative contribution of rare and common variants on human phenotypes, as well as parental origin effect of disease risk alleles in >1,000 individuals at minimal cost.

  5. A fast region-based active contour model for boundary detection of echocardiographic images.

    PubMed

    Saini, Kalpana; Dewal, M L; Rohit, Manojkumar

    2012-04-01

    This paper presents the boundary detection of atrium and ventricle in echocardiographic images. In case of mitral regurgitation, atrium and ventricle may get dilated. To examine this, doctors draw the boundary manually. Here the aim of this paper is to evolve the automatic boundary detection for carrying out segmentation of echocardiography images. Active contour method is selected for this purpose. There is an enhancement of Chan-Vese paper on active contours without edges. Our algorithm is based on Chan-Vese paper active contours without edges, but it is much faster than Chan-Vese model. Here we have developed a method by which it is possible to detect much faster the echocardiographic boundaries. The method is based on the region information of an image. The region-based force provides a global segmentation with variational flow robust to noise. Implementation is based on level set theory so it easy to deal with topological changes. In this paper, Newton-Raphson method is used which makes possible the fast boundary detection.

  6. Fast gas heating in N2/O2 mixtures under nanosecond surface dielectric barrier discharge: the effects of gas pressure and composition

    PubMed Central

    Nudnova, M. M; Kindysheva, S. V; Aleksandrov, N. L; Starikovskii, A. Yu

    2015-01-01

    The fractional electron power quickly transferred to heat in non-equilibrium plasmas was studied experimentally and theoretically in N2/O2 mixtures subjected to high electric fields. Measurements were performed in and after a nanosecond surface dielectric barrier discharge at various (300–750 Torr) gas pressures and (50–100%) N2 percentages. Observations showed that the efficiency of fast gas heating is almost independent of pressure and becomes more profound when the fraction of O2 in N2/O2 mixtures increases. The processes that contribute towards the fast transfer of electron energy to thermal energy were numerically simulated under the conditions considered. Calculations were compared with measurements and the main channels of fast gas heating were analysed at the gas pressures, compositions and electric fields under study. It was shown that efficient fast gas heating in the mixtures with high fraction of O2 is due to a notable contribution of heat release during quenching of electronically excited N2 states in collisions with O2 molecules and to ion–ion recombination. The effect of hydrocarbon addition to air on fast gas heating was numerically estimated. It was concluded that the fractional electron power transferred to heat in air, as a first approximation, could be used to estimate this effect in lean and stoichiometric hydrocarbon–air mixtures. PMID:26170431

  7. Electrostatic-based model for alumina surfaces

    NASA Astrophysics Data System (ADS)

    Streitz, F. H.; Mintmire, J. W.

    1994-12-01

    As most technologically important metals will form oxides readily, any complete study of adhesion at real metal surfaces must include the metal-oxide interface. The role of this ubiquitous oxide layer cannot be overlooked, as the adhesive properties of the oxide or oxide-metal system can be expected to differ profoundly from the adhesive properties of a bare metal surface. We report on the development of a novel computational method for molecular dynamics simulations which explicitly includes variable charge transfer between anions and cations. This method is found to be capable of describing the elastic properties, surface energies, and surface relaxation of crystalline metal-oxides accurately. We discuss in detail results using this method of alpha-alumina and several of its low index faces.

  8. Experience With Bayesian Image Based Surface Modeling

    NASA Technical Reports Server (NTRS)

    Stutz, John C.

    2005-01-01

    Bayesian surface modeling from images requires modeling both the surface and the image generation process, in order to optimize the models by comparing actual and generated images. Thus it differs greatly, both conceptually and in computational difficulty, from conventional stereo surface recovery techniques. But it offers the possibility of using any number of images, taken under quite different conditions, and by different instruments that provide independent and often complementary information, to generate a single surface model that fuses all available information. I describe an implemented system, with a brief introduction to the underlying mathematical models and the compromises made for computational efficiency. I describe successes and failures achieved on actual imagery, where we went wrong and what we did right, and how our approach could be improved. Lastly I discuss how the same approach can be extended to distinct types of instruments, to achieve true sensor fusion.

  9. Effects of simulation-based practice on focused assessment with sonography for trauma (FAST) window identification, acquisition, and diagnosis.

    PubMed

    Chung, Gregory K W K; Gyllenhammer, Ruth G; Baker, Eva L; Savitsky, Eric

    2013-10-01

    We compared the effects of simulator-based virtual ultrasound scanning practice with classroom-based ultrasound scanning practice on participants' knowledge of focused assessment with sonography for trauma (FAST) window quadrants and interpretation, and on participants' performance on live patient FAST examinations. Novices with little or no ultrasound training experience received simulation-based practice (n = 24) or classroom-based practice (n = 24). Participants who received simulation-based practice scored significantly higher on interpreting static images of FAST windows. On live patient examinations where participants scanned the right upper quadrant (RUQ), left upper quadrant (LUQ), and suprapubic quadrant of a normal patient and an ascites-positive patient, the classroom-based practice condition had a shorter scan time for the LUQ and a higher number of participants attaining high-quality window on the RUQ (normal patient only) and suprapubic quadrant (positive patient only) and correct window interpretation on the LUQ (normal patient only). Overall, classroom-based practice appeared to promote physical acquisition skills and simulator-based practice appeared to promote window interpretation skills. Accurate window interpretation is critical to identification of blunt abdominal trauma injuries. The simulator used (SonoSimulator) appears promising as a training tool to increase probe time and to increase exposure to FAST windows reflecting various anatomy and disease states.

  10. A Fast Multi-Object Extraction Algorithm Based on Cell-Based Connected Components Labeling

    NASA Astrophysics Data System (ADS)

    Gu, Qingyi; Takaki, Takeshi; Ishii, Idaku

    We describe a cell-based connected component labeling algorithm to calculate the 0th and 1st moment features as the attributes for labeled regions. These can be used to indicate their sizes and positions for multi-object extraction. Based on the additivity in moment features, the cell-based labeling algorithm can label divided cells of a certain size in an image by scanning the image only once to obtain the moment features of the labeled regions with remarkably reduced computational complexity and memory consumption for labeling. Our algorithm is a simple-one-time-scan cell-based labeling algorithm, which is suitable for hardware and parallel implementation. We also compared it with conventional labeling algorithms. The experimental results showed that our algorithm is faster than conventional raster-scan labeling algorithms.

  11. A comparative study of Powell's and Downhill Simplex algorithms for a fast multimodal surface matching in brain imaging.

    PubMed

    Bernon, J L; Boudousq, V; Rohmer, J F; Fourcade, M; Zanca, M; Rossi, M; Mariano-Goulart, D

    2001-01-01

    Multimodal images registration can be very helpful for diagnostic applications. However, even if a lot of registration algorithms exist, only a few really work in clinical routines. We developed a method based on surface matching and compared two minimization algorithms: Powell's and Downhill Simplex. We studied the influence of some factors (chamfer map computation, number and order of parameters to determine, minimization criteria) on the final accuracy of the algorithm. Using this comparison, we improved some processing steps to allow a clinical use, and selected the simplex algorithm which presented the best results.

  12. Sensitive and Fast Humidity Sensor Based on A Redox Conducting Supramolecular Ionic Material for Respiration Monitoring.

    PubMed

    Yan, Hailong; Zhang, Li; Yu, Ping; Mao, Lanqun

    2017-01-03

    Real-time monitoring of respiratory rate (RR) is highly important for human health, clinical diagnosis, and fundamental scientific research. Exhaled humidity-based RR monitoring has recently attracted increased attention because of its accuracy and portability. Here, we report a new design of an exhaled humidity sensor for the real-time monitoring of the RR based on a synthetic redox conducting supramolecular ionic material (SIM). The humidity-dependent conducting SIM is prepared by ionic self-assembly in aqueous solutions of electroactive 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,10-bis(3-methylimidazolium-1-yl) decane (C10(mim)2). By taking full advantage of the high hygroscopicity and water stability arising from the ionic and hydrophobic interactions between two building blocks (i.e., ABTS and C10(mim)2), the SIM-based humidity sensor exhibits both high sensitivity (less than 0.1% relative humidity) and fast response time (∼37 ms). These excellent properties allow this humidity sensor to noninvasively monitor the RRs of not only humans but also rats that have a much faster RR and much smaller tidal volume than humans. Moreover, this sensor could also be efficiently used for the real-time monitoring of the recovery process of rats from anesthesia.

  13. Diffuse correlation spectroscopy with a fast Fourier transform-based software autocorrelator

    NASA Astrophysics Data System (ADS)

    Dong, Jing; Bi, Renzhe; Ho, Jun Hui; Thong, Patricia S. P.; Soo, Khee-Chee; Lee, Kijoon

    2012-09-01

    Diffuse correlation spectroscopy (DCS) is an emerging noninvasive technique that probes the deep tissue blood flow, by using the time-averaged intensity autocorrelation function of the fluctuating diffuse reflectance signal. We present a fast Fourier transform (FFT)-based software autocorrelator that utilizes the graphical programming language LabVIEW (National Instruments) to complete data acquisition, recording, and processing tasks. The validation and evaluation experiments were conducted on an in-house flow phantom, human forearm, and photodynamic therapy (PDT) on mouse tumors under the acquisition rate of ˜400 kHz. The software autocorrelator in general has certain advantages, such as flexibility in raw photon count data preprocessing and low cost. In addition to that, our FFT-based software autocorrelator offers smoother starting and ending plateaus when compared to a hardware correlator, which could directly benefit the fitting results without too much sacrifice in speed. We show that the blood flow index (BFI) obtained by using a software autocorrelator exhibits better linear behavior in a phantom control experiment when compared to a hardware one. The results indicate that an FFT-based software autocorrelator can be an alternative solution to the conventional hardware ones in DCS systems with considerable benefits.

  14. Infrared image guidance for ground vehicle based on fast wavelet image focusing and tracking

    NASA Astrophysics Data System (ADS)

    Akiyama, Akira; Kobayashi, Nobuaki; Mutoh, Eiichiro; Kumagai, Hideo; Yamada, Hirofumi; Ishii, Hiromitsu

    2009-08-01

    We studied the infrared image guidance for ground vehicle based on the fast wavelet image focusing and tracking. Here we uses the image of the uncooled infrared imager mounted on the two axis gimbal system and the developed new auto focusing algorithm on the Daubechies wavelet transform. The developed new focusing algorithm on the Daubechies wavelet transform processes the result of the high pass filter effect to meet the direct detection of the objects. This new focusing gives us the distance information of the outside world smoothly, and the information of the gimbal system gives us the direction of objects in the outside world to match the sense of the spherical coordinate system. We installed this system on the hand made electric ground vehicle platform powered by 24VDC battery. The electric vehicle equips the rotary encoder units and the inertia rate sensor units to make the correct navigation process. The image tracking also uses the developed newt wavelet focusing within several image processing. The size of the hand made electric ground vehicle platform is about 1m long, 0.75m wide, 1m high, and 50kg weight. We tested the infrared image guidance for ground vehicle based on the new wavelet image focusing and tracking using the electric vehicle indoor and outdoor. The test shows the good results by the developed infrared image guidance for ground vehicle based on the new wavelet image focusing and tracking.

  15. Robust and fast license plate detection based on the fusion of color and edge feature

    NASA Astrophysics Data System (ADS)

    Cai, De; Shi, Zhonghan; Liu, Jin; Hu, Chuanping; Mei, Lin; Qi, Li

    2014-11-01

    Extracting a license plate is an important stage in automatic vehicle identification. The degradation of images and the computation intense make this task difficult. In this paper, a robust and fast license plate detection based on the fusion of color and edge feature is proposed. Based on the dichromatic reflection model, two new color ratios computed from the RGB color model are introduced and proved to be two color invariants. The global color feature extracted by the new color invariants improves the method's robustness. The local Sobel edge feature guarantees the method's accuracy. In the experiment, the detection performance is good. The detection results show that this paper's method is robust to the illumination, object geometry and the disturbance around the license plates. The method can also detect license plates when the color of the car body is the same as the color of the plates. The processing time for image size of 1000x1000 by pixels is nearly 0.2s. Based on the comparison, the performance of the new ratios is comparable to the common used HSI color model.

  16. A fast algorithm for voxel-based deterministic simulation of X-ray imaging

    NASA Astrophysics Data System (ADS)

    Li, Ning; Zhao, Hua-Xia; Cho, Sang-Hyun; Choi, Jung-Gil; Kim, Myoung-Hee

    2008-04-01

    Deterministic method based on ray tracing technique is known as a powerful alternative to the Monte Carlo approach for virtual X-ray imaging. The algorithm speed is a critical issue in the perspective of simulating hundreds of images, notably to simulate tomographic acquisition or even more, to simulate X-ray radiographic video recordings. We present an algorithm for voxel-based deterministic simulation of X-ray imaging using voxel-driven forward and backward perspective projection operations and minimum bounding rectangles (MBRs). The algorithm is fast, easy to implement, and creates high-quality simulated radiographs. As a result, simulated radiographs can typically be obtained in split seconds with a simple personal computer. Program summaryProgram title: X-ray Catalogue identifier: AEAD_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAD_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 416 257 No. of bytes in distributed program, including test data, etc.: 6 018 263 Distribution format: tar.gz Programming language: C (Visual C++) Computer: Any PC. Tested on DELL Precision 380 based on a Pentium D 3.20 GHz processor with 3.50 GB of RAM Operating system: Windows XP Classification: 14, 21.1 Nature of problem: Radiographic simulation of voxelized objects based on ray tracing technique. Solution method: The core of the simulation is a fast routine for the calculation of ray-box intersections and minimum bounding rectangles, together with voxel-driven forward and backward perspective projection operations. Restrictions: Memory constraints. There are three programs in all. A. Program for test 3.1(1): Object and detector have axis-aligned orientation; B. Program for test 3.1(2): Object in arbitrary orientation; C. Program for test 3.2: Simulation of X-ray video

  17. A Fast SVD-Hidden-nodes based Extreme Learning Machine for Large-Scale Data Analytics.

    PubMed

    Deng, Wan-Yu; Bai, Zuo; Huang, Guang-Bin; Zheng, Qing-Hua

    2016-05-01

    Big dimensional data is a growing trend that is emerging in many real world contexts, extending from web mining, gene expression analysis, protein-protein interaction to high-frequency financial data. Nowadays, there is a growing consensus that the increasing dimensionality poses impeding effects on the performances of classifiers, which is termed as the "peaking phenomenon" in the field of machine intelligence. To address the issue, dimensionality reduction is commonly employed as a preprocessing step on the Big dimensional data before building the classifiers. In this paper, we propose an Extreme Learning Machine (ELM) approach for large-scale data analytic. In contrast to existing approaches, we embed hidden nodes that are designed using singular value decomposition (SVD) into the classical ELM. These SVD nodes in the hidden layer are shown to capture the underlying characteristics of the Big dimensional data well, exhibiting excellent generalization performances. The drawback of using SVD on the entire dataset, however, is the high computational complexity involved. To address this, a fast divide and conquer approximation scheme is introduced to maintain computational tractability on high volume data. The resultant algorithm proposed is labeled here as Fast Singular Value Decomposition-Hidden-nodes based Extreme Learning Machine or FSVD-H-ELM in short. In FSVD-H-ELM, instead of identifying the SVD hidden nodes directly from the entire dataset, SVD hidden nodes are derived from multiple random subsets of data sampled from the original dataset. Comprehensive experiments and comparisons are conducted to assess the FSVD-H-ELM against other state-of-the-art algorithms. The results obtained demonstrated the superior generalization performance and efficiency of the FSVD-H-ELM.

  18. GPU-based fast Monte Carlo dose calculation for proton therapy.

    PubMed

    Jia, Xun; Schümann, Jan; Paganetti, Harald; Jiang, Steve B

    2012-12-07

    Accurate radiation dose calculation is essential for successful proton radiotherapy. Monte Carlo (MC) simulation is considered to be the most accurate method. However, the long computation time limits it from routine clinical applications. Recently, graphics processing units (GPUs) have been widely used to accelerate computationally intensive tasks in radiotherapy. We have developed a fast MC dose calculation package, gPMC, for proton dose calculation on a GPU. In gPMC, proton transport is modeled by the class II condensed history simulation scheme with a continuous slowing down approximation. Ionization, elastic and inelastic proton nucleus interactions are considered. Energy straggling and multiple scattering are modeled. Secondary electrons are not transported and their energies are locally deposited. After an inelastic nuclear interaction event, a variety of products are generated using an empirical model. Among them, charged nuclear fragments are terminated with energy locally deposited. Secondary protons are stored in a stack and transported after finishing transport of the primary protons, while secondary neutral particles are neglected. gPMC is implemented on the GPU under the CUDA platform. We have validated gPMC using the TOPAS/Geant4 MC code as the gold standard. For various cases including homogeneous and inhomogeneous phantoms as well as a patient case, good agreements between gPMC and TOPAS/Geant4 are observed. The gamma passing rate for the 2%/2 mm criterion is over 98.7% in the region with dose greater than 10% maximum dose in all cases, excluding low-density air regions. With gPMC it takes only 6-22 s to simulate 10 million source protons to achieve ∼1% relative statistical uncertainty, depending on the phantoms and energy. This is an extremely high efficiency compared to the computational time of tens of CPU hours for TOPAS/Geant4. Our fast GPU-based code can thus facilitate the routine use of MC dose calculation in proton therapy.

  19. GPU-based fast Monte Carlo dose calculation for proton therapy

    NASA Astrophysics Data System (ADS)

    Jia, Xun; Schümann, Jan; Paganetti, Harald; Jiang, Steve B.

    2012-12-01

    Accurate radiation dose calculation is essential for successful proton radiotherapy. Monte Carlo (MC) simulation is considered to be the most accurate method. However, the long computation time limits it from routine clinical applications. Recently, graphics processing units (GPUs) have been widely used to accelerate computationally intensive tasks in radiotherapy. We have developed a fast MC dose calculation package, gPMC, for proton dose calculation on a GPU. In gPMC, proton transport is modeled by the class II condensed history simulation scheme with a continuous slowing down approximation. Ionization, elastic and inelastic proton nucleus interactions are considered. Energy straggling and multiple scattering are modeled. Secondary electrons are not transported and their energies are locally deposited. After an inelastic nuclear interaction event, a variety of products are generated using an empirical model. Among them, charged nuclear fragments are terminated with energy locally deposited. Secondary protons are stored in a stack and transported after finishing transport of the primary protons, while secondary neutral particles are neglected. gPMC is implemented on the GPU under the CUDA platform. We have validated gPMC using the TOPAS/Geant4 MC code as the gold standard. For various cases including homogeneous and inhomogeneous phantoms as well as a patient case, good agreements between gPMC and TOPAS/Geant4 are observed. The gamma passing rate for the 2%/2 mm criterion is over 98.7% in the region with dose greater than 10% maximum dose in all cases, excluding low-density air regions. With gPMC it takes only 6-22 s to simulate 10 million source protons to achieve ˜1% relative statistical uncertainty, depending on the phantoms and energy. This is an extremely high efficiency compared to the computational time of tens of CPU hours for TOPAS/Geant4. Our fast GPU-based code can thus facilitate the routine use of MC dose calculation in proton therapy.

  20. Automatic building detection based on Purposive FastICA (PFICA) algorithm using monocular high resolution Google Earth images

    NASA Astrophysics Data System (ADS)

    Ghaffarian, Saman; Ghaffarian, Salar

    2014-11-01

    This paper proposes an improved FastICA model named as Purposive FastICA (PFICA) with initializing by a simple color space transformation and a novel masking approach to automatically detect buildings from high resolution Google Earth imagery. ICA and FastICA algorithms are defined as Blind Source Separation (BSS) techniques for unmixing source signals using the reference data sets. In order to overcome the limitations of the ICA and FastICA algorithms and make them purposeful, we developed a novel method involving three main steps: 1-Improving the FastICA algorithm using Moore-Penrose pseudo inverse matrix model, 2-Automated seeding of the PFICA algorithm based on LUV color space and proposed simple rules to split image into three regions; shadow + vegetation, baresoil + roads and buildings, respectively, 3-Masking out the final building detection results from PFICA outputs utilizing the K-means clustering algorithm with two number of clusters and conducting simple morphological operations to remove noises. Evaluation of the results illustrates that buildings detected from dense and suburban districts with divers characteristics and color combinations using our proposed method have 88.6% and 85.5% overall pixel-based and object-based precision performances, respectively.

  1. Ion Beam Analysis Of Silicon-Based Surfaces And Correlation With Surface Energy Measurements

    SciTech Connect

    Xing Qian; Herbots, N.; Hart, M.; Bradley, J. D.; Wilkens, B. J.; Sell, D. A.; Culbertson, R. J.; Whaley, S. D.; Sell, Clive H.; Kwong, Henry Mark Jr.

    2011-06-01

    The water affinity of Si-based surfaces is quantified by contact angle measurement and surface free energy to explain hydrophobic or hydrophilic behavior of silicone, silicates, and silicon surfaces. Surface defects such as dangling bonds, surface free energy including Lewis acid-base and Lifshitz-van der Waals components are discussed. Water nucleation and condensation is further explained by surface topography. Tapping mode atomic force microscopy (TMAFM) provides statistical analysis of the topography of these Si-based surfaces. The correlation of the above two characteristics describes the behavior of water condensation at Si-based surfaces. Surface root mean square roughness increasing from several A ring to several nm is found to provide nucleation sites that expedite water condensation visibly for silica and silicone. Hydrophilic surfaces have a condensation pattern that forms puddles of water while hydrophobic surfaces form water beads. Polymer adsorption on these surfaces alters the water affinity as well as the surface topography, and therefore controls condensation on Si-based surfaces including silicone intraocular lens (IOL). The polymer film is characterized by Rutherford backscattering spectrometry (RBS) in conjunction with 4.265 MeV {sup 12}C({alpha}, {alpha}){sup 12}C, 3.045 MeV {sup 16}O({alpha},{alpha}){sup 16}O nuclear resonance scattering (NRS), and 2.8 MeV elastic recoil detection (ERD) of hydrogen for high resolution composition and areal density measurements. The areal density of hydroxypropyl methylcellulose (HPMC) film ranges from 10{sup 18} atom/cm{sup 2} to 10{sup 19} atom/cm{sup 2} gives the silica or silicone surface a roughness of several A ring and a wavelength of 0.16{+-}0.02 {mu}m, and prevents fogging by forming a complete wetting layer during water condensation.

  2. APPLICATION OF HYDROPHILIC STARCH-BASED COATINGS TO POLYETHYLNE SURFACES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methods for imparting hydrophilic surface properties to hydrophobic plastics are of interest because of their ability to retard the build-up of static electricity, to alter friction and adhesion properties between surfaces, to allow surfaces to be printed with water-based dyes and inks, and to impro...

  3. Surface characterization based on optical phase shifting interferometry

    DOEpatents

    Mello, Michael , Rosakis; Ares J.

    2011-08-02

    Apparatus, techniques and systems for implementing an optical interferometer to measure surfaces, including mapping of instantaneous curvature or in-plane and out-of-plane displacement field gradients of a sample surface based on obtaining and processing four optical interferograms from a common optical reflected beam from the sample surface that are relatively separated in phase by .pi./2.

  4. Antarctic and Arctic land-fast sea ice growth rates: an intercomparison based on stable isotope fractionation measurements

    NASA Astrophysics Data System (ADS)

    Smith, I.; Langhorne, P. J.; Gough, A. J.; Leonard, G. H.; Mahoney, A. R.; Eicken, H.; Van Hale, R.; Trodahl, H. J.; Haskell, T.

    2012-12-01

    The growth rate of sea ice (i.e., the change in sea ice thickness with time) is a critical factor affecting the thermohaline circulation because it determines the amount and timing of salt fluxes to the ocean. Studies of the colonisation of sea ice by microorganisms and the timing of ice-algal blooms, evident at depth horizons in sea ice, also require knowledge of growth rates. However, sea ice thickness and in particular growth rates of level ice are poorly known, mostly due to restrictions in remote sensing of these quantities. Direct measurements through repeated drilling, or the use of temperature probes or ultrasonic pingers (such as on ice mass balance buoys) are resource intensive, and are therefore limited to a few sites. An ideal methodology would allow retrospective reconstruction of sea ice growth rates from the analysis of ice cores taken at the end of the growth season. Previously developed methods have included salinity-based growth rate models, growth history deductions from thick section structural analysis and growth rate models based on the measurement of oxygen isotope fractionation in sea ice. In this presentation, we focus on the latter and compare measured growth rates with those derived from an existing isotope fractionation based model (Eicken, Ant. Res. Ser., 1998). In addition, comparisons are made with measured seasonal changes in δ18O values in Antarctic surface waters. The data presented have been collected for land-fast sea ice from McMurdo Sound, Antarctica and the Chukchi Sea near Barrow, Alaska. These two locations are ideally suited for this intercomparison study because both locations have a long history of sea ice and ocean observations. The Antarctic sea ice data are influenced by the appearance of waters from beneath an ice shelf. The Arctic sea ice growth rate and isotope data are from two sites, and are supported by oceanographic data, including under-ice current speeds, from a nearby mooring. Previous measurements of Arctic

  5. Fast Gaussian kernel learning for classification tasks based on specially structured global optimization.

    PubMed

    Zhong, Shangping; Chen, Tianshun; He, Fengying; Niu, Yuzhen

    2014-09-01

    For a practical pattern classification task solved by kernel methods, the computing time is mainly spent on kernel learning (or training). However, the current kernel learning approaches are based on local optimization techniques, and hard to have good time performances, especially for large datasets. Thus the existing algorithms cannot be easily extended to large-scale tasks. In this paper, we present a fast Gaussian kernel learning method by solving a specially structured global optimization (SSGO) problem. We optimize the Gaussian kernel function by using the formulated kernel target alignment criterion, which is a difference of increasing (d.i.) functions. Through using a power-transformation based convexification method, the objective criterion can be represented as a difference of convex (d.c.) functions with a fixed power-transformation parameter. And the objective programming problem can then be converted to a SSGO problem: globally minimizing a concave function over a convex set. The SSGO problem is classical and has good solvability. Thus, to find the global optimal solution efficiently, we can adopt the improved Hoffman's outer approximation method, which need not repeat the searching procedure with different starting points to locate the best local minimum. Also, the proposed method can be proven to converge to the global solution for any classification task. We evaluate the proposed method on twenty benchmark datasets, and compare it with four other Gaussian kernel learning methods. Experimental results show that the proposed method stably achieves both good time-efficiency performance and good classification performance.

  6. Fast Wavelet Based Functional Models for Transcriptome Analysis with Tiling Arrays

    PubMed Central

    Clement, Lieven; De Beuf, Kristof; Thas, Olivier; Vuylsteke, Marnik; Irizarry, Rafael A.; Crainiceanu, Ciprian M.

    2013-01-01

    For a better understanding of the biology of an organism, a complete description is needed of all regions of the genome that are actively transcribed. Tiling arrays are used for this purpose. They allow for the discovery of novel transcripts and the assessment of differential expression between two or more experimental conditions such as genotype, treatment, tissue, etc. In tiling array literature, many efforts are devoted to transcript discovery, whereas more recent developments also focus on differential expression. To our knowledge, however, no methods for tiling arrays have been described that can simultaneously assess transcript discovery and identify differentially expressed transcripts. In this paper, we adopt wavelet based functional models to the context of tiling arrays. The high dimensionality of the data triggered us to avoid inference based on Bayesian MCMC methods. Instead, we introduce a fast empirical Bayes method that provides adaptive regularization of the functional effects. A simulation study and a case study illustrate that our approach is well suited for the simultaneous assessment of transcript discovery and differential expression in tiling array studies, and that it outperforms methods that accomplish only one of these tasks. PMID:22499683

  7. Fast video shot boundary detection based on SVD and pattern matching.

    PubMed

    Lu, Zhe-Ming; Shi, Yong

    2013-12-01

    Video shot boundary detection (SBD) is the first and essential step for content-based video management and structural analysis. Great efforts have been paid to develop SBD algorithms for years. However, the high computational cost in the SBD becomes a block for further applications such as video indexing, browsing, retrieval, and representation. Motivated by the requirement of the real-time interactive applications, a unified fast SBD scheme is proposed in this paper. We adopted a candidate segment selection and singular value decomposition (SVD) to speed up the SBD. Initially, the positions of the shot boundaries and lengths of gradual transitions are predicted using adaptive thresholds and most non-boundary frames are discarded at the same time. Only the candidate segments that may contain the shot boundaries are preserved for further detection. Then, for all frames in each candidate segment, their color histograms in the hue-saturation-value) space are extracted, forming a frame-feature matrix. The SVD is then performed on the frame-feature matrices of all candidate segments to reduce the feature dimension. The refined feature vector of each frame in the candidate segments is obtained as a new metric for boundary detection. Finally, cut and gradual transitions are identified using our pattern matching method based on a new similarity measurement. Experiments on TRECVID 2001 test data and other video materials show that the proposed scheme can achieve a high detection speed and excellent accuracy compared with recent SBD schemes.

  8. Accurate and fast simulation of channel noise in conductance-based model neurons by diffusion approximation.

    PubMed

    Linaro, Daniele; Storace, Marco; Giugliano, Michele

    2011-03-01

    Stochastic channel gating is the major source of intrinsic neuronal noise whose functional consequences at the microcircuit- and network-levels have been only partly explored. A systematic study of this channel noise in large ensembles of biophysically detailed model neurons calls for the availability of fast numerical methods. In fact, exact techniques employ the microscopic simulation of the random opening and closing of individual ion channels, usually based on Markov models, whose computational loads are prohibitive for next generation massive computer models of the brain. In this work, we operatively define a procedure for translating any Markov model describing voltage- or ligand-gated membrane ion-conductances into an effective stochastic version, whose computer simulation is efficient, without compromising accuracy. Our approximation is based on an improved Langevin-like approach, which employs stochastic differential equations and no Montecarlo methods. As opposed to an earlier proposal recently debated in the literature, our approximation reproduces accurately the statistical properties of the exact microscopic simulations, under a variety of conditions, from spontaneous to evoked response features. In addition, our method is not restricted to the Hodgkin-Huxley sodium and potassium currents and is general for a variety of voltage- and ligand-gated ion currents. As a by-product, the analysis of the properties emerging in exact Markov schemes by standard probability calculus enables us for the first time to analytically identify the sources of inaccuracy of the previous proposal, while providing solid ground for its modification and improvement we present here.

  9. Reference Beam Pattern Design for Frequency Invariant Beamforming Based on Fast Fourier Transform

    PubMed Central

    Zhang, Wang; Su, Tao

    2016-01-01

    In the field of fast Fourier transform (FFT)-based frequency invariant beamforming (FIB), there is still an unsolved problem. That is the selection of the reference beam to make the designed wideband pattern frequency invariant (FI) over a given frequency range. This problem is studied in this paper. The research shows that for a given array, the selection of the reference beam pattern is determined by the number of sensors and the ratio of the highest frequency to the lowest frequency of the signal (RHL). The length of the weight vector corresponding to a given reference beam pattern depends on the reference frequency. In addition, the upper bound of the weight length to ensure the FI property over the whole frequency band of interest is also given. When the constraints are added to the reference beam, it does not affect the FI property of the designed wideband beam as long as the symmetry of the reference beam is ensured. Based on this conclusion, a scheme for reference beam design is proposed. PMID:27669242

  10. A Fast Radiative Transfer Model for the Meteor- M satellite-based hyperspectral IR sounders

    NASA Astrophysics Data System (ADS)

    Uspensky, A. B.; Rublev, A. N.; Rusin, E. V.; Pyatkin, V. P.

    2014-12-01

    The methodological and computational aspects of Fast Radiative Transfer Model (FRTM) development designed for the analysis and validation of the data of measurements using satellite-based instrument-hyperspectral IR sounders of high spectral resolution—are considered. A description of the FRTM is given for the analysis and modeling of the measurements by the IRFS-2 IR Fourier spectrometer for polarorbiting meteorological satellites of the Meteor-M series based on the known RTTOV FRTM. Computational efficiency is estimated and the results of the verification of developed FRTM are presented. They were obtained from a comparison of model simulations with exact line-by-line calculations for the IRFS-2 IR sounder. The increase in computational performance and the accuracy of the FRTM, caused by the application of the algorithms of the principal components method, are discussed. The construction of radiative models, which use the algorithm of the Monte Carlo method and are applicable for the analysis and modeling of the data of IR sounders under conditions of cloudiness in the instrument field of view, is considered.

  11. Reference Beam Pattern Design for Frequency Invariant Beamforming Based on Fast Fourier Transform.

    PubMed

    Zhang, Wang; Su, Tao

    2016-09-22

    In the field of fast Fourier transform (FFT)-based frequency invariant beamforming (FIB), there is still an unsolved problem. That is the selection of the reference beam to make the designed wideband pattern frequency invariant (FI) over a given frequency range. This problem is studied in this paper. The research shows that for a given array, the selection of the reference beam pattern is determined by the number of sensors and the ratio of the highest frequency to the lowest frequency of the signal (RHL). The length of the weight vector corresponding to a given reference beam pattern depends on the reference frequency. In addition, the upper bound of the weight length to ensure the FI property over the whole frequency band of interest is also given. When the constraints are added to the reference beam, it does not affect the FI property of the designed wideband beam as long as the symmetry of the reference beam is ensured. Based on this conclusion, a scheme for reference beam design is proposed.

  12. Estimates for Pu-239 loadings in burial ground culverts based on fast/slow neutron measurements

    SciTech Connect

    Winn, W.G.; Hochel, R.C.; Hofstetter, K.J.; Sigg, R.A.

    1989-08-15

    This report provides guideline estimates for Pu-239 mass loadings in selected burial ground culverts. The relatively high recorded Pu-239 contents of these culverts have been appraised as suspect relative to criticality concerns, because they were assayed only with the solid waste monitor (SWM) per gamma-ray counting. After 1985, subsequent waste was also assayed with the neutron coincidence counter (NCC), and a comparison of the assay methods showed that the NCC generally yielded higher assays than the SWM. These higher NCC readings signaled a need to conduct non-destructive/non-intrusive nuclear interrogations of these culverts, and a technical team conducted scoping measurements to illustrate potential assay methods based on neutron and/or gamma counting. A fast/slow neutron method has been developed to estimate the Pu-239 in the culverts. In addition, loading records include the SWM assays of all Pu-239 cuts of some of the culvert drums and these data are useful in estimating the corresponding NCC drum assays from NCC vs SWM data. Together, these methods yield predictions based on direct measurements and statistical inference.

  13. Fast k-space-based evaluation of imaging properties of ultrasound apertures

    NASA Astrophysics Data System (ADS)

    Zapf, M.; Dapp, R.; Hardt, M.; Henning, P. A.; Ruiter, N. V.

    2011-03-01

    At the Karlsruhe Institute of Technology (KIT) a three-dimensional ultrasound computer tomography (3D USCT) system for early breast cancer diagnosis is being developed. This method promises reproducible volume images of the female breast in 3D. Initial measurements and a simulation based optimization method, which took several physical properties into account, led to a new aperture setup. Yet this simulation is computational too demanding to systematically evaluate the different 'virtual' apertures which can be achieved by rotation and lifting of the system. In optics a Fourier based approach is available to simulate imaging systems as linear systems. For the two apertures used in our project and one hypothetical linear array aperture this concept was evaluated and compared to a reference simulation. An acceptable conformity between the new approach and the reference simulation could be shown. With this approach a fast evaluation of optimal 'virtual' apertures for specific measurement objects and imaging constraints can be carried out within an acceptable time constraint.

  14. Fast optimization method based on the diffuser dot density for uniformity of the backlight module.

    PubMed

    Huang, Bing-Le; Guo, Tai-Liang

    2016-02-20

    A fast optimization method based on the diffuser dot density (DDD) for uniformity of the backlight module (BLM) is proposed in the paper. First, the relationship between the efficiency of the light emerging and the DDD is analyzed, and then a simulation model that is employed to acquire a serial of simulating data is constructed. Second, a mathematic method to profit the relationship is adopted, and a polynomial relationship is derived. Finally, an algorithm to adjust the DDD and optimize the uniformity of the BLM based on the DDD is constructed. The simulation results prove that only by three times optimization, the uniformity of the BLM can reach 85.6%, and the experimental result indicates that the algorithm proposed in the paper can improve the uniformity rapidly. The final experimental result is that the uniformity of the third optimization reaches 77.4%, which satisfies the target 75% in the phase of designing the BLM. Compared to the conventional optimization method, the method can speed up the procedure and lower the expense of developing the BLM in fabricating the liquid-crystal display.

  15. Specification of hierarchical-model-based fast quarter-pixel motion estimation

    NASA Astrophysics Data System (ADS)

    Cho, Junsang; Suh, Jung W.; Jeon, Gwanggil; Jeong, Jechang

    2010-06-01

    We propose a robust and fast quarter-pixel motion estimation algorithm. This algorithm is an advanced version of the previously proposed model-based quarter-pixel motion estimation (MBQME). MBQME has many advantages in computational complexity, running speed, and hardware implementations. But it has the problem that it does not find the quarter-pixel positions that locate beyond the half-pixel positions. That is one of limitations of model-based motion estimation methods, and it leads to both peak-SNR degradation and bit-rate increase. To solve this problem, we propose a hierarchical mathematical model with minimum interpolations. Through this model, we can determine a motion vector at every quarter-pixel point, which is perfectly compatible with the quarter-pixel motion estimation method within international video coding standards such as MPEG-4 and H.264/AVC. The simulation results show that the proposed method yields almost the same or even better peak-SNR performance than that of full-search quarter-pixel motion estimation, with much lower computational complexity.

  16. Accurate calculation and Matlab based fast realization of merit function's Hesse matrix for the design of multilayer optical coating

    NASA Astrophysics Data System (ADS)

    Wu, Su-Yong; Long, Xing-Wu; Yang, Kai-Yong

    2009-09-01

    To improve the current status of home multilayer optical coating design with low speed and poor efficiency when a large layer number occurs, the accurate calculation and fast realization of merit function’s gradient and Hesse matrix is pointed out. Based on the matrix method to calculate the spectral properties of multilayer optical coating, an analytic model is established theoretically. And the corresponding accurate and fast computation is successfully achieved by programming with Matlab. Theoretical and simulated results indicate that this model is mathematically strict and accurate, and its maximal precision can reach floating-point operations in the computer, with short time and fast speed. Thus it is very suitable to improve the optimal search speed and efficiency of local optimization methods based on the derivatives of merit function. It has outstanding performance in multilayer optical coating design with a large layer number.

  17. Retrieval of Areal-averaged Spectral Surface Albedo from Transmission Data Alone: Computationally Simple and Fast Approach

    SciTech Connect

    Kassianov, Evgueni I.; Barnard, James C.; Flynn, Connor J.; Riihimaki, Laura D.; Michalsky, Joseph; Hodges, G. B.

    2014-10-25

    We introduce and evaluate a simple retrieval of areal-averaged surface albedo using ground-based measurements of atmospheric transmission alone at five wavelengths (415, 500, 615, 673 and 870nm), under fully overcast conditions. Our retrieval is based on a one-line semi-analytical equation and widely accepted assumptions regarding the weak spectral dependence of cloud optical properties, such as cloud optical depth and asymmetry parameter, in the visible and near-infrared spectral range. To illustrate the performance of our retrieval, we use as input measurements of spectral atmospheric transmission from Multi-Filter Rotating Shadowband Radiometer (MFRSR). These MFRSR data are collected at two well-established continental sites in the United States supported by the U.S. Department of Energy’s (DOE’s) Atmospheric Radiation Measurement (ARM) Program and National Oceanic and Atmospheric Administration (NOAA). The areal-averaged albedos obtained from the MFRSR are compared with collocated and coincident Moderate Resolution Imaging Spectroradiometer (MODIS) white-sky albedo. In particular, these comparisons are made at four MFRSR wavelengths (500, 615, 673 and 870nm) and for four seasons (winter, spring, summer and fall) at the ARM site using multi-year (2008-2013) MFRSR and MODIS data. Good agreement, on average, for these wavelengths results in small values (≤0.01) of the corresponding root mean square errors (RMSEs) for these two sites. The obtained RMSEs are comparable with those obtained previously for the shortwave albedos (MODIS-derived versus tower-measured) for these sites during growing seasons. We also demonstrate good agreement between tower-based daily-averaged surface albedos measured for “nearby” overcast and non-overcast days. Thus, our retrieval originally developed for overcast conditions likely can be extended for non-overcast days by interpolating between overcast retrievals.

  18. Fast computation of Hessian-based enhancement filters for medical images.

    PubMed

    Yang, Shih-Feng; Cheng, Ching-Hsue

    2014-10-01

    This paper presents a method for fast computation of Hessian-based enhancement filters, whose conditions for identifying particular structures in medical images are associated only with the signs of Hessian eigenvalues. The computational costs of Hessian-based enhancement filters come mainly from the computation of Hessian eigenvalues corresponding to image elements to obtain filter responses, because computing eigenvalues of a matrix requires substantial computational effort. High computational cost has become a challenge in the application of Hessian-based enhancement filters. Using a property of the characteristic polynomial coefficients of a matrix and the well-known Routh-Hurwitz criterion in control engineering, it is shown that under certain conditions, the response of a Hessian-based enhancement filter to an image element can be obtained without having to compute Hessian eigenvalues. The computational cost can thus be reduced. Experimental results on several medical images show that the method proposed in this paper can reduce significantly the number of computations of Hessian eigenvalues and the processing times of images. The percentage reductions of the number of computations of Hessian eigenvalues for enhancing blob- and tubular-like structures in two-dimensional images are approximately 90% and 65%, respectively. For enhancing blob-, tubular-, and plane-like structures in three-dimensional images, the reductions are approximately 97%, 75%, and 12%, respectively. For the processing times, the percentage reductions for enhancing blob- and tubular-like structures in two-dimensional images are approximately 31% and 7.5%, respectively. The reductions for enhancing blob-, tubular-, and plane-like structures in three-dimensional images are approximately 68%, 55%, and 3%, respectively.

  19. Nanoparticle-based etching of silicon surfaces

    DOEpatents

    Branz, Howard [Boulder, CO; Duda, Anna [Denver, CO; Ginley, David S [Evergreen, CO; Yost, Vernon [Littleton, CO; Meier, Daniel [Atlanta, GA; Ward, James S [Golden, CO

    2011-12-13

    A method (300) of texturing silicon surfaces (116) such to reduce reflectivity of a silicon wafer (110) for use in solar cells. The method (300) includes filling (330, 340) a vessel (122) with a volume of an etching solution (124) so as to cover the silicon surface 116) of a wafer or substrate (112). The etching solution (124) is made up of a catalytic nanomaterial (140) and an oxidant-etchant solution (146). The catalytic nanomaterial (140) may include gold or silver nanoparticles or noble metal nanoparticles, each of which may be a colloidal solution. The oxidant-etchant solution (146) includes an etching agent (142), such as hydrofluoric acid, and an oxidizing agent (144), such as hydrogen peroxide. Etching (350) is performed for a period of time including agitating or stirring the etching solution (124). The etch time may be selected such that the etched silicon surface (116) has a reflectivity of less than about 15 percent such as 1 to 10 percent in a 350 to 1000 nanometer wavelength range.

  20. Ferroelectric based catalysis: Switchable surface chemistry

    NASA Astrophysics Data System (ADS)

    Kakekhani, Arvin; Ismail-Beigi, Sohrab

    2015-03-01

    We describe a new class of catalysts that uses an epitaxial monolayer of a transition metal oxide on a ferroelectric substrate. The ferroelectric polarization switches the surface chemistry between strongly adsorptive and strongly desorptive regimes, circumventing difficulties encountered on non-switchable catalytic surfaces where the Sabatier principle dictates a moderate surface-molecule interaction strength. This method is general and can, in principle, be applied to many reactions, and for each case the choice of the transition oxide monolayer can be optimized. Here, as a specific example, we show how simultaneous NOx direct decomposition (into N2 and O2) and CO oxidation can be achieved efficiently on CrO2 terminated PbTiO3, while circumventing oxygen (and sulfur) poisoning issues. One should note that NOx direct decomposition has been an open challenge in automotive emission control industry. Our method can expand the range of catalytically active elements to those which are not conventionally considered for catalysis and which are more economical, e.g., Cr (for NOx direct decomposition and CO oxidation) instead of canonical precious metal catalysts. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

  1. Fast Mean-Shift Based Classification of Very High Resolution Images: Application to Forest Cover Mapping

    NASA Astrophysics Data System (ADS)

    Boukir, S.; Jones, S.; Reinke, K.

    2012-07-01

    This paper presents a new unsupervised classification method which aims to effectively and efficiently map remote sensing data. The Mean-Shift (MS) algorithm, a non parametric density-based clustering technique, is at the core of our method. This powerful clustering algorithm has been successfully used for both the classification and the segmentation of gray scale and color images during the last decade. However, very little work has been reported regarding the performance of this technique on remotely sensed images. The main disadvantage of the MS algorithm lies on its high computational costs. Indeed, it is based on an optimization procedure to determine the modes of the pixels density. To investigate the MS algorithm in the difficult context of very high resolution remote sensing imagery, we use a fast version of this algorithm which has been recently proposed, namely the Path-Assigned Mean Shift (PAMS). This algorithm is up to 5 times faster than other fast MS algorithms while inducing a low loss in quality compared to the original MS version. To compensate for this loss, we propose to use the K modes (cluster centroids) obtained after convergence of the PAMS algorithm as an initialization of a K-means clustering algorithm. The latter converges very quickly to a refined solution to the underlying clustering problem. Furthermore, it does not suffer the main drawback of the classic K-means algorithm (the number of clusters K needs to be specified) as K is automatically determined via the MS mode-seeking procedure. We demonstrate the effectiveness of this two-stage clustering method in performing automatic classification of aerial forest images. Both individual bands and band combination trails are presented. When compared to the classical PAMS algorithm, our technique is better in terms of classification quality. The improvement in classification is significant both visually and statistically. The whole classification process is performed in a few seconds on

  2. Options for a lunar base surface architecture

    NASA Technical Reports Server (NTRS)

    Roberts, Barney B.

    1991-01-01

    The analysis of the Space Exploration Initiative architectures involves making definitions of systems engineering designs for the construction of lunar and Mars bases for the support of science, exploration, and resource production on these planets. This paper discusses the results of the Space Resource Utilization Architecture study, which was initiated to develop the technical capability for extracting useful materials from the indigenous resources of the moon and Mars. For the moon, an infrastructure concept of a base is designed which can support a crew of 12. The major phases of the lunar-base development, the systems and the elements involved, and the physical layout and evolution of the base are described.

  3. Fiber-optic-based surface plasmon resonance (SPR) sensors for the detection of toxic nerve agents

    NASA Astrophysics Data System (ADS)

    Prakash, Anna M. C.; Kim, Yoon-Chang; Banerji, Soame; Masson, Jean-Francois; Booksh, Karl S.

    2004-03-01

    Analytical instruments capable of detecting nerve agents in battlefield conditions where speed, accuracy and ease of operation are a must in today's military. Fast detection and decontamination of nerve agents in very low concentrations is the primary focus of our research. The method presented here focuses on optimizing polymer stabilized sensing elements on the surface of SPR fiber-optic probes. A number of polymers & polymer supported metal complexes capable of reversibly binding to the species of interest & which have robust operation in hostile environments are incorporated with the fiber optic sensing elements. An optical technique, such as Surface Plasmon Resonance (SPR), better suited to rapid data collection without sample pretreatment is employed. The approach using polymer-based optical fibers with off-the-shelf SPR system components has been tested for the detection of Pinacolyl methylphosphonate (PMP), a simulant for nerve agent Soman. Surface initiated polymeric sensors have higher sensitivity toward detecting PMP than bulk-polymerized sensors.

  4. The relationship between contrast, resolution and detectability in accelerator-based fast neutron radiography

    SciTech Connect

    Ambrosi, R. M.; Watterson, J. I. W.

    1999-06-10

    Fast neutron radiography as a method for non destructive testing is a fast growing field of research. At the Schonland Research Center for Nuclear Sciences we have been engaged in the formulation of a model for the physics of image formation in fast neutron radiography (FNR). This involves examining all the various factors that affect image formation in FNR by experimental and Monte Carlo methods. One of the major problems in the development of a model for fast neutron radiography is the determination of the factors that affect image contrast and resolution. Monte Carlo methods offer an ideal tool for the determination of the origin of many of these factors. In previous work the focus of these methods has been the determination of the scattered neutron field in both a scintillator and a fast neutron radiography facility. As an extension of this work MCNP has been used to evaluate the role neutron scattering in a specimen plays in image detectability. Image processing of fast neutron radiographs is a necessary method of enhancing the detectability of features in an image. MCNP has been used to determine the part it can play in indirectly improving image resolution and aiding in image processing. The role noise plays in fast neutron radiography and its impact on image reconstruction has been evaluated. All these factors aid in the development of a model describing the relationship between contrast, resolution and detectability.

  5. SU-E-T-806: Very Fast GPU-Based IMPT Dose Computation

    SciTech Connect

    Sullivan, A; Brand, M

    2015-06-15

    Purpose: Designing particle therapy treatment plans is a dosimetrist-in-the-loop optimization wherein the conflicting constraints of achieving a desired tumor dose distribution must be balanced against the need to minimize the dose to nearby OARs. IMPT introduces an additional, inner, numerical optimization step in which the dosimetrist’s current set of constraints are used to determine the weighting of beam spots. Very fast dose calculations are needed to enable the dosimetrist to perform many iterations of the outer optimization in a commercially reasonable time. Methods: We have developed a GPU-based convolution-type dose computation algorithm that more accurately handles heterogeneities than earlier algorithms by redistributing energy from dose computed in a water volume. The depth dependence of the beam size is handled by pre-processing Bragg curves using a weighted superposition of Gaussian bases. Additionally, scattering, the orientation of treatment ports, and the non-parallel propagation of beams are handled by large, but sparse, energy-redistribution matrices that implement affine transforms. Results: We tested our algorithm using a brain tumor dataset with 1 mm voxels and a single treatment port from the patient’s anterior through the sinuses. The resulting dose volume is 100 × 100 × 230 mm with 66,200 beam spots on a 3 × 3 × 2 mm grid. The dose computation takes <1 msec on a GeForce GTX Titan GPU with the Gamma passing rate for 2mm/2% criterion of 99.1% compared to dose calculated by an alternative dose algorithm based on pencil beams. We will present comparisons to Monte Carlo dose calculations. Conclusion: Our high-speed dose computation method enables the IMPT spot weights to be optimized in <1 second, resulting in a nearly instantaneous response to user changes to dose constraints. This permits the creation of higher quality plans by allowing the dosimetrist to evaluate more alternatives in a short period of time.

  6. Fast and powerful heritability inference for family-based neuroimaging studies

    PubMed Central

    Ganjgahi, Habib; Winkler, Anderson M.; Glahn, David C.; Blangero, John; Kochunov, Peter; Nichols, Thomas E.

    2015-01-01

    Heritability estimation has become an important tool for imaging genetics studies. The large number of voxel- and vertex-wise measurements in imaging genetics studies presents a challenge both in terms of computational intensity and the need to account for elevated false positive risk because of the multiple testing problem. There is a gap in existing tools, as standard neuroimaging software cannot estimate heritability, and yet standard quantitative genetics tools cannot provide essential neuroimaging inferences, like family-wise error corrected voxel-wise or cluster-wiseP-values. Moreover, available heritability tools rely on P-values that can be inaccurate with usual parametric inference methods. In this work we develop fast estimation and inference procedures for voxel-wise heritability, drawing on recent methodological results that simplify heritability likelihood computations (Blangero etal., 2013). We review the family of score and Wald tests and propose novel inference methods based on explained sum of squares of an auxiliary linear model. To address problems with inaccuracies with the standard results used to find P-values, we propose four different permutation schemes to allow semi-parametric inference (parametric likelihood-based estimation, non-parametric sampling distribution). In total, we evaluate 5 different significance tests for heritability, with either asymptotic parametric or permutation-basedP-value computations. We identify a number of tests that are both computationally efficient and powerful, making them ideal candidates for heritability studies in the massive data setting. We illustrate our method on fractional anisotropy measures in 859 subjects from the Genetics of Brain Structure study. PMID:25812717

  7. High-fidelity, broadband stimulated-Brillouin-scattering-based slow light using fast noise modulation.

    PubMed

    Zhu, Yunhui; Lee, Myungjun; Neifeld, Mark A; Gauthier, Daniel J

    2011-01-17

    We demonstrate a 5-GHz-broadband tunable slow-light device based on stimulated Brillouin scattering in a standard highly-nonlinear optical fiber pumped by a noise-current-modulated laser beam. The noisemodulation waveform uses an optimized pseudo-random distribution of the laser drive voltage to obtain an optimal flat-topped gain profile, which minimizes the pulse distortion and maximizes pulse delay for a given pump power. In comparison with a previous slow-modulation method, eye-diagram and signal-to-noise ratio (SNR) analysis show that this broadband slow-light technique significantly increases the fidelity of a delayed data sequence, while maintaining the delay performance. A fractional delay of 0.81 with a SNR of 5.2 is achieved at the pump power of 350 mW using a 2-km-long highly nonlinear fiber with the fast noise-modulation method, demonstrating a 50% increase in eye-opening and a 36% increase in SNR in the comparison.

  8. Support vector machine based classification of fast Fourier transform spectroscopy of proteins

    NASA Astrophysics Data System (ADS)

    Lazarevic, Aleksandar; Pokrajac, Dragoljub; Marcano, Aristides; Melikechi, Noureddine

    2009-02-01

    Fast Fourier transform spectroscopy has proved to be a powerful method for study of the secondary structure of proteins since peak positions and their relative amplitude are affected by the number of hydrogen bridges that sustain this secondary structure. However, to our best knowledge, the method has not been used yet for identification of proteins within a complex matrix like a blood sample. The principal reason is the apparent similarity of protein infrared spectra with actual differences usually masked by the solvent contribution and other interactions. In this paper, we propose a novel machine learning based method that uses protein spectra for classification and identification of such proteins within a given sample. The proposed method uses principal component analysis (PCA) to identify most important linear combinations of original spectral components and then employs support vector machine (SVM) classification model applied on such identified combinations to categorize proteins into one of given groups. Our experiments have been performed on the set of four different proteins, namely: Bovine Serum Albumin, Leptin, Insulin-like Growth Factor 2 and Osteopontin. Our proposed method of applying principal component analysis along with support vector machines exhibits excellent classification accuracy when identifying proteins using their infrared spectra.

  9. A fast SPAD-based small animal imager for early-photon diffuse optical tomography.

    PubMed

    Mu, Ying; Niedre, Mark

    2014-01-01

    Photon scatter is the dominant light transport process in biological tissue and is well understood to degrade imaging performance in near-infrared diffuse optical tomography. Measurement of photons arriving at early times following a short laser pulse is considered to be an effective method to improve this limitation, i.e. by systematically selecting photons that have experienced fewer scattering events. Previously, we tested the performance of single photon avalanche photodiode (SPAD) in measurement of early transmitted photons through diffusive media and showed that it outperformed photo-multiplier tube (PMT) systems in similar configurations, principally due to its faster temporal response. In this paper, we extended this work and developed a fast SPAD-based time-resolved diffuse optical tomography system. As a first validation of the instrument, we scanned an optical phantom with multiple absorbing inclusions and measured full time-resolved data at 3240 scan points per axial slice. We performed image reconstruction with very early-arriving photon data and showed significant improvements compared to time-integrated data. Extension of this work to mice in vivo and measurement of time-resolved fluorescence data is the subject of ongoing research.

  10. A Generalized Grid-Based Fast Multipole Method for Integrating Helmholtz Kernels.

    PubMed

    Parkkinen, Pauli; Losilla, Sergio A; Solala, Eelis; Toivanen, Elias A; Xu, Wen-Hua; Sundholm, Dage

    2017-02-14

    A grid-based fast multipole method (GB-FMM) for optimizing three-dimensional (3D) numerical molecular orbitals in the bubbles and cube double basis has been developed and implemented. The present GB-FMM method is a generalization of our recently published GB-FMM approach for numerically calculating electrostatic potentials and two-electron interaction energies. The orbital optimization is performed by integrating the Helmholtz kernel in the double basis. The steep part of the functions in the vicinity of the nuclei is represented by one-center bubbles functions, whereas the remaining cube part is expanded on an equidistant 3D grid. The integration of the bubbles part is treated by using one-center expansions of the Helmholtz kernel in spherical harmonics multiplied with modified spherical Bessel functions of the first and second kind, analogously to the numerical inward and outward integration approach for calculating two-electron interaction potentials in atomic structure calculations. The expressions and algorithms for massively parallel calculations on general purpose graphics processing units (GPGPU) are described. The accuracy and the correctness of the implementation has been checked by performing Hartree-Fock self-consistent-field calculations (HF-SCF) on H2, H2O, and CO. Our calculations show that an accuracy of 10(-4) to 10(-7) Eh can be reached in HF-SCF calculations on general molecules.

  11. A Fast Framework for Abrupt Change Detection Based on Binary Search Trees and Kolmogorov Statistic.

    PubMed

    Qi, Jin-Peng; Qi, Jie; Zhang, Qing

    2016-01-01

    Change-Point (CP) detection has attracted considerable attention in the fields of data mining and statistics; it is very meaningful to discuss how to quickly and efficiently detect abrupt change from large-scale bioelectric signals. Currently, most of the existing methods, like Kolmogorov-Smirnov (KS) statistic and so forth, are time-consuming, especially for large-scale datasets. In this paper, we propose a fast framework for abrupt change detection based on binary search trees (BSTs) and a modified KS statistic, named BSTKS (binary search trees and Kolmogorov statistic). In this method, first, two binary search trees, termed as BSTcA and BSTcD, are constructed by multilevel Haar Wavelet Transform (HWT); second, three search criteria are introduced in terms of the statistic and variance fluctuations in the diagnosed time series; last, an optimal search path is detected from the root to leaf nodes of two BSTs. The studies on both the synthetic time series samples and the real electroencephalograph (EEG) recordings indicate that the proposed BSTKS can detect abrupt change more quickly and efficiently than KS, t-statistic (t), and Singular-Spectrum Analyses (SSA) methods, with the shortest computation time, the highest hit rate, the smallest error, and the highest accuracy out of four methods. This study suggests that the proposed BSTKS is very helpful for useful information inspection on all kinds of bioelectric time series signals.

  12. EEG-based classification of fast and slow hand movements using Wavelet-CSP algorithm.

    PubMed

    Robinson, Neethu; Vinod, A P; Ang, Kai Keng; Tee, Keng Peng; Guan, Cuntai T

    2013-08-01

    A brain-computer interface (BCI) acquires brain signals, extracts informative features, and translates these features to commands to control an external device. This paper investigates the application of a noninvasive electroencephalography (EEG)-based BCI to identify brain signal features in regard to actual hand movement speed. This provides a more refined control for a BCI system in terms of movement parameters. An experiment was performed to collect EEG data from subjects while they performed right-hand movement at two different speeds, namely fast and slow, in four different directions. The informative features from the data were obtained using the Wavelet-Common Spatial Pattern (W-CSP) algorithm that provided high-temporal-spatial-spectral resolution. The applicability of these features to classify the two speeds and to reconstruct the speed profile was studied. The results for classifying speed across seven subjects yielded a mean accuracy of 83.71% using a Fisher Linear Discriminant (FLD) classifier. The speed components were reconstructed using multiple linear regression and significant correlation of 0.52 (Pearson's linear correlation coefficient) was obtained between recorded and reconstructed velocities on an average. The spatial patterns of the W-CSP features obtained showed activations in parietal and motor areas of the brain. The results achieved promises to provide a more refined control in BCI by including control of movement speed.

  13. Fast Contour-Tracing Algorithm Based on a Pixel-Following Method for Image Sensors.

    PubMed

    Seo, Jonghoon; Chae, Seungho; Shim, Jinwook; Kim, Dongchul; Cheong, Cheolho; Han, Tack-Don

    2016-03-09

    Contour pixels distinguish objects from the background. Tracing and extracting contour pixels are widely used for smart/wearable image sensor devices, because these are simple and useful for detecting objects. In this paper, we present a novel contour-tracing algorithm for fast and accurate contour following. The proposed algorithm classifies the type of contour pixel, based on its local pattern. Then, it traces the next contour using the previous pixel's type. Therefore, it can classify the type of contour pixels as a straight line, inner corner, outer corner and inner-outer corner, and it can extract pixels of a specific contour type. Moreover, it can trace contour pixels rapidly because it can determine the local minimal path using the contour case. In addition, the proposed algorithm is capable of the compressing data of contour pixels using the representative points and inner-outer corner points, and it can accurately restore the contour image from the data. To compare the performance of the proposed algorithm to that of conventional techniques, we measure their processing time and accuracy. In the experimental results, the proposed algorithm shows better performance compared to the others. Furthermore, it can provide the compressed data of contour pixels and restore them accurately, including the inner-outer corner, which cannot be restored using conventional algorithms.

  14. A Fast Framework for Abrupt Change Detection Based on Binary Search Trees and Kolmogorov Statistic

    PubMed Central

    Qi, Jin-Peng; Qi, Jie; Zhang, Qing

    2016-01-01

    Change-Point (CP) detection has attracted considerable attention in the fields of data mining and statistics; it is very meaningful to discuss how to quickly and efficiently detect abrupt change from large-scale bioelectric signals. Currently, most of the existing methods, like Kolmogorov-Smirnov (KS) statistic and so forth, are time-consuming, especially for large-scale datasets. In this paper, we propose a fast framework for abrupt change detection based on binary search trees (BSTs) and a modified KS statistic, named BSTKS (binary search trees and Kolmogorov statistic). In this method, first, two binary search trees, termed as BSTcA and BSTcD, are constructed by multilevel Haar Wavelet Transform (HWT); second, three search criteria are introduced in terms of the statistic and variance fluctuations in the diagnosed time series; last, an optimal search path is detected from the root to leaf nodes of two BSTs. The studies on both the synthetic time series samples and the real electroencephalograph (EEG) recordings indicate that the proposed BSTKS can detect abrupt change more quickly and efficiently than KS, t-statistic (t), and Singular-Spectrum Analyses (SSA) methods, with the shortest computation time, the highest hit rate, the smallest error, and the highest accuracy out of four methods. This study suggests that the proposed BSTKS is very helpful for useful information inspection on all kinds of bioelectric time series signals. PMID:27413364

  15. Error-Based Observer of a Charge Couple Device Tracking Loop for Fast Steering Mirror

    PubMed Central

    Tang, Tao; Deng, Chao; Yang, Tao; Zhong, Daijun; Ren, Ge; Huang, Yongmei; Fu, Chengyu

    2017-01-01

    The charge couple device (CCD) tracking loop of a fast steering mirror (FSM) is usually used to stabilize line of sight (LOS). High closed-loop bandwidth facilitates good performance. However, low-rate sample and time delay of the CCD greatly limit the high control bandwidth. This paper proposes an error-based observer (EBO) to improve the low-frequency performance of the CCD tracking system. The basic idea is by combining LOS error from the CCD and the controller output to produce the high-gain observer, forwarding into the originally closed-loop control system. This proposed EBO can improve the system both in target tracking and disturbance suppression due to LOS error from the CCD’s sensing of the two signals. From a practical engineering view, the closed-loop stability and robustness of the EBO system are investigated on the condition of gain margin and phase margin of the open-loop transfer function. Two simulations of CCD experiments are provided to verify the benefits of the proposed algorithm. PMID:28264504

  16. Fast terahertz optoelectronic amplitude modulator based on plasmonic metamaterial antenna arrays and graphene

    NASA Astrophysics Data System (ADS)

    Jessop, David S.; Sol, Christian W. O.; Xiao, Long; Kindness, Stephen J.; Braeuninger-Weimer, Philipp; Lin, Hungyen; Griffiths, Jonathan P.; Ren, Yuan; Kamboj, Varun S.; Hofmann, Stephan; Zeitler, J. Axel; Beere, Harvey E.; Ritchie, David A.; Degl'Innocenti, Riccardo

    2016-02-01

    The growing interest in terahertz (THz) technologies in recent years has seen a wide range of demonstrated applications, spanning from security screening, non-destructive testing, gas sensing, to biomedical imaging and communication. Communication with THz radiation offers the advantage of much higher bandwidths than currently available, in an unallocated spectrum. For this to be realized, optoelectronic components capable of manipulating THz radiation at high speeds and high signal-to-noise ratios must be developed. In this work we demonstrate a room temperature frequency dependent optoelectronic amplitude modulator working at around 2 THz, which incorporates graphene as the tuning medium. The architecture of the modulator is an array of plasmonic dipole antennas surrounded by graphene. By electrostatically doping the graphene via a back gate electrode, the reflection characteristics of the modulator are modified. The modulator is electrically characterized to determine the graphene conductivity and optically characterization, by THz time-domain spectroscopy and a single-mode 2 THz quantum cascade laser, to determine the optical modulation depth and cut-off frequency. A maximum optical modulation depth of ~ 30% is estimated and is found to be most (least) sensitive when the electrical modulation is centered at the point of maximum (minimum) differential resistivity of the graphene. A 3 dB cut-off frequency > 5 MHz, limited only by the area of graphene on the device, is reported. The results agree well with theoretical calculations and numerical simulations, and demonstrate the first steps towards ultra-fast, graphene based THz optoelectronic devices.

  17. A Low-Cost and Fast Real-Time PCR System Based on Capillary Convection.

    PubMed

    Qiu, Xianbo; Ge, Shengxiang; Gao, Pengfei; Li, Ke; Yang, Yongliang; Zhang, Shiyin; Ye, Xiangzhong; Xia, Ningshao; Qian, Shizhi

    2017-02-01

    A low-cost and fast real-time PCR system in a pseudo-isothermal manner with disposable capillary tubes based on thermal convection for point-of-care diagnostics is developed and tested. Once stable temperature gradient along the capillary tube has been established, a continuous circulatory flow or thermal convection inside the capillary tube will repeatedly transport PCR reagents through temperature zones associated with the DNA denaturing, annealing, and extension stages of the reaction. To establish stable temperature gradient along the capillary tube, a dual-temperature heating strategy with top and bottom heaters is adopted here. A thermal waveguide is adopted for precise maintenance of the temperature of the top heater. An optimized optical network is developed for monitoring up to eight amplification units for real-time fluorescence detection. The system performance was demonstrated with repeatable detection of influenza A (H1N1) virus nucleic acid targets with a limit of detection of 1.0 TCID50/mL within 30 min.

  18. Fast-dissolving tablets of glyburide based on ternary solid dispersions with PEG 6000 and surfactants.

    PubMed

    Cirri, Marzia; Maestrelli, Francesca; Corti, Giovanna; Mura, Paola; Valleri, Maurizio

    2007-04-01

    Marketed glyburide tablets present unsatisfying dissolution profiles that give rise to variable bioavailability. With the purpose of developing a fast-dissolving tablet formulation able to assure a complete drug dissolution, we investigated the effect of the addition to a reference tablet formulation of different types (anionic and nonionic) and amounts of hydrophilic surfactants, as well as the use of a new technique, based on ternary solid dispersions of the drug with an hydrophilic carrier (polyethylene glycol [PEG] 6000) and a surfactant. Tablets were prepared by direct compression or previous wet granulation of suitable formulations containing the drug with each surfactant or drug:PEG:surfactant ternary dispersions at different PEG:surfactant w/w ratios. The presence of surfactants significantly increased (p<0.01) the drug dissolution rate, but complete drug dissolution was never achieved. On the contrary, in all cases tablets containing ternary solid dispersions achieved 100% dissolved drug within 60 min. The best product was the 10:80:10 w/w ternary dispersion with PEG 6000 and sodium laurylsulphate, showing a dissolution efficiency 5.5-fold greater than the reference tablet formulation and 100% drug dissolution after only 20 min.

  19. A Fast Method to Predict Distributions of Binary Black Hole Masses Based on Gaussian Process Regression

    NASA Astrophysics Data System (ADS)

    Yun, Yuqi; Zevin, Michael; Sampson, Laura; Kalogera, Vassiliki

    2017-01-01

    With more observations from LIGO in the upcoming years, we will be able to construct an observed mass distribution of black holes to compare with binary evolution simulations. This will allow us to investigate the physics of binary evolution such as the effects of common envelope efficiency and wind strength, or the properties of the population such as the initial mass function.However, binary evolution codes become computationally expensive when running large populations of binaries over a multi-dimensional grid of input parameters, and may simulate accurately only for a limited combination of input parameter values. Therefore we developed a fast machine-learning method that utilizes Gaussian Mixture Model (GMM) and Gaussian Process (GP) regression, which together can predict distributions over the entire parameter space based on a limited number of simulated models. Furthermore, Gaussian Process regression naturally provides interpolation errors in addition to interpolation means, which could provide a means of targeting the most uncertain regions of parameter space for running further simulations.We also present a case study on applying this new method to predicting chirp mass distributions for binary black hole systems (BBHs) in Milky-way like galaxies of different metallicities.

  20. Spatiotemporal focusing-based widefield multiphoton microscopy for fast optical sectioning of thick tissues

    NASA Astrophysics Data System (ADS)

    Cheng, Li-Chung; Chang, Chia-Yuan; Yen, Wei-Chung; Chen, Shean-Jen

    2012-10-01

    Conventional multiphoton microscopy employs beam scanning; however, in this study a microscope based on spatiotemporal focusing offering widefield multiphoton excitation has been developed to provide fast optical sectioning images. The microscope integrates a 10 kHz repetition rate ultrafast amplifier featuring strong instantaneous peak power (maximum 400 μJ/pulse at 90 fs pulse width) with a TE-cooled, ultra-sensitive photon detecting, electron multiplying charge-coupled device camera. This configuration can produce multiphoton excited images with an excitation area larger than 200 × 100 μm2 at a frame rate greater than 100 Hz. Brownian motions of fluorescent microbeads as small as 0.5 μm have been instantaneously observed with a lateral spatial resolution of less than 0.5 μm and an axial resolution of approximately 3.5 μm. Moreover, we combine the widefield multiphoton microscopy with structure illuminated technique named HiLo to reject the background scattering noise to get better quality for bioimaging.

  1. Nanometal-decorated exfoliated graphite nanoplatelet based glucose biosensors with high sensitivity and fast response.

    PubMed

    Lu, Jue; Do, Inhwan; Drzal, Lawrence T; Worden, Robert M; Lee, Ilsoon

    2008-09-23

    We report the novel fabrication of a highly sensitive, selective, fast responding, and affordable amperometric glucose biosensor using exfoliated graphite nanoplatelets (xGnPs) decorated with Pt and Pd nanoparticles. Nafion was used to solubilize metal-decorated graphite nanoplatelets, and a simple cast method with high content organic solvent (85 wt %) was used to prepare the biosensors. The addition of precious metal nanoparticles such as platinum (Pt) and palladium (Pd) to xGnP increased the electroactive area of the electrode and substantially decreased the overpotential in the detection of hydrogen peroxide. The Pt-xGnP glucose biosensor had a sensitivity of 61.5+/-0.6 microA/(mM x cm(2)) and gave a linear response up to 20 mM. The response time and detection limit (S/N=3) were determined to be 2 s and 1 microM, respectively. Therefore, this novel glucose biosensor based on the Pt nanoparticle coated xGnP is among the best reported to date in both sensing performance and production cost. In addition, the effects of metal nanoparticle loading and the particle size on the biosensor performance were systematically investigated.

  2. Development of an AQUA Based Near-Surface Parameter Retrieval

    NASA Technical Reports Server (NTRS)

    Roberts, Brent; Clayson, Carol Anne

    2010-01-01

    The production of a satellite based turbulent surface flux product relies critically upon the near-surface input parameters. Development of retrieval algorithms for the necessary near-surface variables of wind speed, specific humidity, air temperature, and sea surface temperature has proceeded relatively independent of each another until recently. The use of a neural network approach using Special Sensor Microwave/Imager (SSM/I) data in conjunction with a first guess sea surface temperature has led to successful retrieval of all parameters simultaneously. However, SSM/I frequencies lack inherent sensitivity to the sea surface temperature (SST). Recent studies have found improved air temperature and humidity retrievals can be obtained via inclusion of microwave sounding channels weighted in the lower troposphere. The inclusion of SSM/I-like frequencies as well as SST-sensitive microwave channels on AMSR-E along with AMSU-A sounding data onboard the AQUA platform provides an unique opportunity. That is the ability to provide near-simultaneous (in space and time) measurements allowing the retrieval of all the near-surface variables, including SST. This study shows results of a new algorithm designed to take advantage of the unique sampling ability of AQUA based sensors. Results from a neural network based methodology will be shown as compared to in-situ based observations of near-surface variables. Implications for creation of an AQUA based turbulent surface product are also discussed.

  3. How Fast Is Fast?

    ERIC Educational Resources Information Center

    Korn, Abe

    1994-01-01

    Presents an activity that enables students to answer for themselves the question of how fast a body must travel before the nonrelativistic expression must be replaced with the correct relativistic expression by deciding on the accuracy required in describing the kinetic energy of a body. (ZWH)

  4. Fast volumetric imaging with patterned illumination via digital micro-mirror device-based temporal focusing multiphoton microscopy

    PubMed Central

    Chang, Chia-Yuan; Hu, Yvonne Yuling; Lin, Chun-Yu; Lin, Cheng-Han; Chang, Hsin-Yu; Tsai, Sheng-Feng; Lin, Tzu-Wei; Chen, Shean-Jen

    2016-01-01

    Temporal focusing multiphoton microscopy (TFMPM) has the advantage of area excitation in an axial confinement of only a few microns; hence, it can offer fast three-dimensional (3D) multiphoton imaging. Herein, fast volumetric imaging via a developed digital micromirror device (DMD)-based TFMPM has been realized through the synchronization of an electron multiplying charge-coupled device (EMCCD) with a dynamic piezoelectric stage for axial scanning. The volumetric imaging rate can achieve 30 volumes per second according to the EMCCD frame rate of more than 400 frames per second, which allows for the 3D Brownian motion of one-micron fluorescent beads to be spatially observed. Furthermore, it is demonstrated that the dynamic HiLo structural multiphoton microscope can reject background noise by way of the fast volumetric imaging with high-speed DMD patterned illumination. PMID:27231617

  5. Fast valve based on double-layer eddy-current repulsion for disruption mitigation in Experimental Advanced Superconducting Tokamak.

    PubMed

    Zhuang, H D; Zhang, X D

    2015-05-01

    A fast valve based on the double-layer eddy-current repulsion mechanism has been developed on Experimental Advanced Superconducting Tokamak (EAST). In addition to a double-layer eddy-current coil, a preload system was added to improve the security of the valve, whereby the valve opens more quickly and the open-valve time becomes shorter, making it much safer than before. In this contribution, testing platforms, open-valve characteristics, and throughput of the fast valve are discussed. Tests revealed that by choosing appropriate parameters the valve opened within 0.15 ms, and open-valve times were no longer than 2 ms. By adjusting working parameter values, the maximum number of particles injected during this open-valve time was estimated at 7 × 10(22). The fast valve will become a useful tool to further explore disruption mitigation experiments on EAST in 2015.

  6. Fast GC-FID based metabolic fingerprinting of Japanese green tea leaf for its quality ranking prediction.

    PubMed

    Jumtee, Kanokwan; Bamba, Takeshi; Fukusaki, Eiichiro

    2009-07-01

    There is a need of reliable, rapid, and cost-effective analysis technique to evaluate food and crop compositions, which are important to improve their qualities and quantities. Prior to fast GC-FID development, metabolic fingerprints, and predictive models obtained from a conventional GC-FID were evaluated by comparison to those derived from GC-TOF-MS. A similar chromatographic pattern with higher sensitivity of polyphenol compounds including epicatechin gallate (ECg) and epigallocatechin gallate (EGCg) had been achieved by using conventional GC-FID. Fast gas chromatograph coupled with flame ionization detector (GC-FID) has been carried out with 10 m x 0.18 mm id x 0.20 microm df capillary column. The analysis time per sample was reduced to less than 14 min compared to those of a conventional GC-FID (38 min) and GC-TOF-MS (28 min). The fast GC-FID also offered reliable retention time reproducibility without significant loss of peak resolution. Projections to latent structures by means of partial least squares (PLS) with orthogonal signal correction filtering (OSC) was applied to the fast GC-FID data. The predictive model showed good model fit and predictability with RMSEP of 3.464, suggesting that fast GC-FID based metabolic fingerprinting could be an alternative method for the prediction of Japanese green tea quality.

  7. Evaluation and application of a fast module in a PLC based interlock and control system

    NASA Astrophysics Data System (ADS)

    Zaera-Sanz, M.

    2009-08-01

    The LHC Beam Interlock system requires a controller performing a simple matrix function to collect the different beam dump requests. To satisfy the expected safety level of the Interlock, the system should be robust and reliable. The PLC is a promising candidate to fulfil both aspects but too slow to meet the expected response time which is of the order of μseconds. Siemens has introduced a ``so called'' fast module (FM352-5 Boolean Processor). It provides independent and extremely fast control of a process within a larger control system using an onboard processor, a Field Programmable Gate Array (FPGA), to execute code in parallel which results in extremely fast scan times. It is interesting to investigate its features and to evaluate it as a possible candidate for the beam interlock system. This paper publishes the results of this study. As well, this paper could be useful for other applications requiring fast processing using a PLC.

  8. A fast video clip retrieval algorithm based on VA-file

    NASA Astrophysics Data System (ADS)

    Liu, Fangjie; Dong, DaoGuo; Miao, Xiaoping; Xue, XiangYang

    2003-12-01

    Video clip retrieval is a significant research topic of content-base multimedia retrieval. Generally, video clip retrieval process is carried out as following: (1) segment a video clip into shots; (2) extract a key frame from each shot as its representative; (3) denote every key frame as a feature vector, and thus a video clip can be denoted as a sequence of feature vectors; (4) retrieve match clip by computing the similarity between the feature vector sequence of a query clip and the feature vector sequence of any clip in database. To carry out fast video clip retrieval the index structure is indispensable. According to our literature survey, S2-tree [17] is the one and only index structure having been applied to support video clip retrieval, which combines the characteristics of both X-tree and Suffix-tree and converts the series vectors retrieval to string matching. But S2-tree structure will not be applicable if the feature vector's dimension is beyond 20, because the X-tree itself cannot be used to sustain similarity query effectively when dimensions of vectors are beyond 20. Furthermore, it cannot support flexible similarity definitions between two vector sequences. VA-file represents the vector approximately by compressing the original data and it maintains the original order when representing vectors in a sequence, which is a very valuable merit for vector sequences matching. In this paper, a new video clip similarity model as well as video clip retrieval algorithm based on VA-File are proposed. The experiments show that our algorithm incredibly shortened the retrieval time compared to sequential scanning without index structure.

  9. A fast color image enhancement algorithm based on Max Intensity Channel.

    PubMed

    Sun, Wei; Han, Long; Guo, Baolong; Jia, Wenyan; Sun, Mingui

    2014-03-30

    In this paper, we extend image enhancement techniques based on the retinex theory imitating human visual perception of scenes containing high illumination variations. This extension achieves simultaneous dynamic range modification, color consistency, and lightness rendition without multi-scale Gaussian filtering which has a certain halo effect. The reflection component is analyzed based on the illumination and reflection imaging model. A new prior named Max Intensity Channel (MIC) is implemented assuming that the reflections of some points in the scene are very high in at least one color channel. Using this prior, the illumination of the scene is obtained directly by performing a gray-scale closing operation and a fast cross-bilateral filtering on the MIC of the input color image. Consequently, the reflection component of each RGB color channel can be determined from the illumination and reflection imaging model. The proposed algorithm estimates the illumination component which is relatively smooth and maintains the edge details in different regions. A satisfactory color rendition is achieved for a class of images that do not satisfy the gray-world assumption implicit to the theoretical foundation of the retinex. Experiments are carried out to compare the new method with several spatial and transform domain methods. Our results indicate that the new method is superior in enhancement applications, improves computation speed, and performs well for images with high illumination variations than other methods. Further comparisons of images from National Aeronautics and Space Administration and a wearable camera eButton have shown a high performance of the new method with better color restoration and preservation of image details.

  10. A combinatorial chemistry method for fast screening of perovskite-based NO oxidation catalyst.

    PubMed

    Yoon, Dal Young; Lim, Eunho; Kim, Young Jin; Cho, Byong K; Nam, In-Sik; Choung, Jin Woo; Yoo, Seungbeom

    2014-11-10

    A fast parallel screening method based on combinatorial chemistry (combichem) has been developed and applied in the screening tests of perovskite-based oxide (PBO) catalysts for NO oxidation to hit a promising PBO formulation for the oxidation of NO to NO2. This new method involves three consecutive steps: oxidation of NO to NO2 over a PBO catalyst, adsorption of NOx onto the PBO and K2O/Al2O3, and colorimetric assay of the NOx adsorbed thereon. The combichem experimental data have been used for determining the oxidation activity of NO over PBO catalysts as well as three critical parameters, such as the adsorption efficiency of K2O/Al2O3 for NO2 (α) and NO (β), and the time-average fraction of NO included in the NOx feed stream (ξ). The results demonstrated that the amounts of NO2 produced over PBO catalysts by the combichem method under transient conditions correlate well with those from a conventional packed-bed reactor under steady-state conditions. Among the PBO formulations examined, La0.5Ag0.5MnO3 has been identified as the best chemical formulation for oxidation of NO to NO2 by the present combichem method and also confirmed by the conventional packed-bed reactor tests. The superior efficiency of the combichem method for high-throughput catalyst screening test validated in this study is particularly suitable for saving the time and resources required in developing a new formulation of PBO catalyst whose chemical composition may have an enormous number of possible variations.

  11. Determinants of Fast Food Consumption among Iranian High School Students Based on Planned Behavior Theory

    PubMed Central

    Sharifirad, Gholamreza; Yarmohammadi, Parastoo; Azadbakht, Leila; Morowatisharifabad, Mohammad Ali; Hassanzadeh, Akbar

    2013-01-01

    Objective. This study was conducted to identify some factors (beliefs and norms) which are related to fast food consumption among high school students in Isfahan, Iran. We used the framework of the theory planned behavior (TPB) to predict this behavior. Subjects & Methods. Cross-sectional data were available from high school students (n = 521) who were recruited by cluster randomized sampling. All of the students completed a questionnaire assessing variables of standard TPB model including attitude, subjective norms, perceived behavior control (PBC), and the additional variables past behavior, actual behavior control (ABC). Results. The TPB variables explained 25.7% of the variance in intentions with positive attitude as the strongest (β = 0.31, P < 0.001) and subjective norms as the weakest (β = 0.29, P < 0.001) determinant. Concurrently, intentions accounted for 6% of the variance for fast food consumption. Past behavior and ABC accounted for an additional amount of 20.4% of the variance in fast food consumption. Conclusion. Overall, the present study suggests that the TPB model is useful in predicting related beliefs and norms to the fast food consumption among adolescents. Subjective norms in TPB model and past behavior in TPB model with additional variables (past behavior and actual behavior control) were the most powerful predictors of fast food consumption. Therefore, TPB model may be a useful framework for planning intervention programs to reduce fast food consumption by students. PMID:23936635

  12. A no-reference perceptual blurriness metric based fast super-resolution of still pictures using sparse representation

    NASA Astrophysics Data System (ADS)

    Choi, Jae-Seok; Bae, Sung-Ho; Kim, Munchurl

    2015-03-01

    In recent years, perceptually-driven super-resolution (SR) methods have been proposed to lower computational complexity. Furthermore, sparse representation based super-resolution is known to produce competitive high-resolution images with lower computational costs compared to other SR methods. Nevertheless, super-resolution is still difficult to be implemented with substantially low processing power for real-time applications. In order to speed up the processing time of SR, much effort has been made with efficient methods, which selectively incorporate elaborate computation algorithms for perceptually sensitive image regions based on a metric, such as just noticeable distortion (JND). Inspired by the previous works, we first propose a novel fast super-resolution method with sparse representation, which incorporates a no-reference just noticeable blur (JNB) metric. That is, the proposed fast super-resolution method efficiently generates super-resolution images by selectively applying a sparse representation method for perceptually sensitive image areas which are detected based on the JNB metric. Experimental results show that our JNB-based fast super-resolution method is about 4 times faster than a non-perceptual sparse representation based SR method for 256× 256 test LR images. Compared to a JND-based SR method, the proposed fast JNB-based SR method is about 3 times faster, with approximately 0.1 dB higher PSNR and a slightly higher SSIM value in average. This indicates that our proposed perceptual JNB-based SR method generates high-quality SR images with much lower computational costs, opening a new possibility for real-time hardware implementations.

  13. Terahertz-optical-asymmetric-demultiplexer (TOAD)-based arithmetic units for ultra-fast optical information processing

    NASA Astrophysics Data System (ADS)

    Cherri, Abdallah K.

    2010-04-01

    In this paper, designs of ultra-fast all-optical based Terahertz-optical-asymmetric-demultiplexer (TOAD)-based devices are reported. Using TOAD switches, adders/subtracters units are demonstrated. The high speed is achieved due to the use of the nonlinear optical materials and the nonbinary modified signed-digit (MSD) number representation. The proposed all-optical circuits are compared in terms of numbers TOAD switches, optical amplifiers and wavelength converters.

  14. Torsemide Fast Dissolving Tablets: Development, Optimization Using Box-Bhenken Design and Response Surface Methodology, In Vitro Characterization, and Pharmacokinetic Assessment.

    PubMed

    El-Shenawy, Ahmed A; Ahmed, Mahmoud M; Mansour, Heba F; Abd El Rasoul, Saleh

    2017-01-03

    The present study planed to develop new fast dissolving tablets (FDTs) of torsemide. Solid dispersions (SDs) of torsemide and sorbitol (3:1) or polyvinylpyrrolidone (PVP) k25 were prepared. The prepared SDs were evaluated for in-vitro dissolution. Fourier transform infrared spectroscopy and differential scanning calorimetry for SDs revealed no drug/excipient interactions and transformation of torsemide to the amorphous form. Torsemide/sorbitol SD was selected for formulation of torsemide FDTs by direct compression method. Box-Bhenken factorial design was employed to design 15 formulations using croscarmellose sodium and crospovidone at different concentrations. The response surface methodology was used to analyze the effect of changing these concentrations (independent variables) on disintegration time (Y1), percentage friability (Y2), and amount torsemide released at 10 min. The physical mixtures of torsemide and the used excipients were evaluated for angle of repose, Hausner's ratio, and Carr's index. The prepared FDTs tablets were evaluated for wetting and disintegration time, weight variation, drug content, percentage friability, thickness, hardness, and in vitro release. Based on the in-vitro results and factorial design characterization, F10 and F7 were selected for bioavailability studies following administration to Albino New Zealand rabbits. They showed significantly higher C max and (AUC0-12) and shorter T max than those obtained after administration of the corresponding ordinary commercial Torseretic ® tablets. Stability study was conducted for F10 that showed good stability upon storage at 30°C/75% RH and 40°C/75% RH for 3 months.

  15. Surface classification and detection of latent fingerprints based on 3D surface texture parameters

    NASA Astrophysics Data System (ADS)

    Gruhn, Stefan; Fischer, Robert; Vielhauer, Claus

    2012-06-01

    In the field of latent fingerprint detection in crime scene forensics the classification of surfaces has importance. A new method for the scientific analysis of image based information for forensic science was investigated in the last years. Our image acquisition based on a sensor using Chromatic White Light (CWL) with a lateral resolution up to 2 μm. The used FRT-MicroProf 200 CWL 600 measurement device is able to capture high-resolution intensity and topography images in an optical and contact-less way. In prior work, we have suggested to use 2D surface texture parameters to classify various materials, which was a novel approach in the field of criminalistic forensic using knowledge from surface appearance and a chromatic white light sensor. A meaningful and useful classification of different crime scene specific surfaces is not existent. In this work, we want to extend such considerations by the usage of fourteen 3D surface parameters, called 'Birmingham 14'. In our experiment we define these surface texture parameters and use them to classify ten different materials in this test set-up and create specific material classes. Further it is shown in first experiments, that some surface texture parameters are sensitive to separate fingerprints from carrier surfaces. So far, the use of surface roughness is mainly known within the framework of material quality control. The analysis and classification of the captured 3D-topography images from crime scenes is important for the adaptive preprocessing depending on the surface texture. The adaptive preprocessing in dependency of surface classification is necessary for precise detection because of the wide variety of surface textures. We perform a preliminary study in usage of these 3D surface texture parameters as feature for the fingerprint detection. In combination with a reference sample we show that surface texture parameters can be an indication for a fingerprint and can be a feature in latent fingerprint detection.

  16. Modeling the Acid-Base Properties of Montmorillonite Edge Surfaces.

    PubMed

    Tournassat, Christophe; Davis, James A; Chiaberge, Christophe; Grangeon, Sylvain; Bourg, Ian C

    2016-12-20

    The surface reactivity of clay minerals remains challenging to characterize because of a duality of adsorption surfaces and mechanisms that does not exist in the case of simple oxide surfaces: edge surfaces of clay minerals have a variable proton surface charge arising from hydroxyl functional groups, whereas basal surfaces have a permanent negative charge arising from isomorphic substitutions. Hence, the relationship between surface charge and surface potential on edge surfaces cannot be described using the Gouy-Chapman relation, because of a spillover of negative electrostatic potential from the basal surface onto the edge surface. While surface complexation models can be modified to account for these features, a predictive fit of experimental data was not possible until recently, because of uncertainty regarding the densities and intrinsic pKa values of edge functional groups. Here, we reexamine this problem in light of new knowledge on intrinsic pKa values obtained over the past decade using ab initio molecular dynamics simulations, and we propose a new formalism to describe edge functional groups. Our simulation results yield reasonable predictions of the best available experimental acid-base titration data.

  17. Novel spirometry based on optical surface imaging

    SciTech Connect

    Li, Guang Huang, Hailiang; Li, Diana G.; Chen, Qing; Gaebler, Carl P.; Mechalakos, James; Wei, Jie; Sullivan, James; Zatcky, Joan; Rimner, Andreas

    2015-04-15

    Purpose: To evaluate the feasibility of using optical surface imaging (OSI) to measure the dynamic tidal volume (TV) of the human torso during free breathing. Methods: We performed experiments to measure volume or volume change in geometric and deformable phantoms as well as human subjects using OSI. To assess the accuracy of OSI in volume determination, we performed experiments using five geometric phantoms and two deformable body phantoms and compared the values with those derived from geometric calculations and computed tomography (CT) measurements, respectively. To apply this technique to human subjects, an institutional review board protocol was established and three healthy volunteers were studied. In the human experiment, a high-speed image capture mode of OSI was applied to acquire torso images at 4–5 frames per second, which was synchronized with conventional spirometric measurements at 5 Hz. An in-house MATLAB program was developed to interactively define the volume of interest (VOI), separate the thorax and abdomen, and automatically calculate the thoracic and abdominal volumes within the VOIs. The torso volume change (TV C = ΔV{sub torso} = ΔV{sub thorax} + ΔV{sub abdomen}) was automatically calculated using full-exhalation phase as the reference. The volumetric breathing pattern (BP{sub v} = ΔV{sub thorax}/ΔV{sub torso}) quantifying thoracic and abdominal volume variations was also calculated. Under quiet breathing, TVC should equal the tidal volume measured concurrently by a spirometer with a conversion factor (1.08) accounting for internal and external differences of temperature and moisture. Another MATLAB program was implemented to control the conventional spirometer that was used as the standard. Results: The volumes measured from the OSI imaging of geometric phantoms agreed with the calculated volumes with a discrepancy of 0.0% ± 1.6% (range −1.9% to 2.5%). In measurements from the deformable torso/thorax phantoms, the volume

  18. Audio video based fast fixed-point independent vector analysis for multisource separation in a room environment

    NASA Astrophysics Data System (ADS)

    Liang, Yanfeng; Naqvi, Syed Mohsen; Chambers, Jonathon A.

    2012-12-01

    Fast fixed-point independent vector analysis (FastIVA) is an improved independent vector analysis (IVA) method, which can achieve faster and better separation performance than original IVA. As an example IVA method, it is designed to solve the permutation problem in frequency domain independent component analysis by retaining the higher order statistical dependency between frequencies during learning. However, the performance of all IVA methods is limited due to the dimensionality of the parameter space commonly encountered in practical frequency-domain source separation problems and the spherical symmetry assumed with the source model. In this article, a particular permutation problem encountered in using the FastIVA algorithm is highlighted, namely the block permutation problem. Therefore a new audio video based fast fixed-point independent vector analysis algorithm is proposed, which uses video information to provide a smart initialization for the optimization problem. The method cannot only avoid the ill convergence resulting from the block permutation problem but also improve the separation performance even in noisy and high reverberant environments. Different multisource datasets including the real audio video corpus AV16.3 are used to verify the proposed method. For the evaluation of the separation performance on real room recordings, a new pitch based evaluation criterion is also proposed.

  19. A New Ticket-Based Authentication Mechanism for Fast Handover in Mesh Network

    PubMed Central

    Lai, Yan-Ming; Cheng, Pu-Jen; Lee, Cheng-Chi; Ku, Chia-Yi

    2016-01-01

    Due to the ever-growing popularity mobile devices of various kinds have received worldwide, the demands on large-scale wireless network infrastructure development and enhancement have been rapidly swelling in recent years. A mobile device holder can get online at a wireless network access point, which covers a limited area. When the client leaves the access point, there will be a temporary disconnection until he/she enters the coverage of another access point. Even when the coverages of two neighboring access points overlap, there is still work to do to make the wireless connection smoothly continue. The action of one wireless network access point passing a client to another access point is referred to as the handover. During handover, for security concerns, the client and the new access point should perform mutual authentication before any Internet access service is practically gained/provided. If the handover protocol is inefficient, in some cases discontinued Internet service will happen. In 2013, Li et al. proposed a fast handover authentication mechanism for wireless mesh network (WMN) based on tickets. Unfortunately, Li et al.’s work came with some weaknesses. For one thing, some sensitive information such as the time and date of expiration is sent in plaintext, which increases security risks. For another, Li et al.’s protocol includes the use of high-quality tamper-proof devices (TPDs), and this unreasonably high equipment requirement limits its applicability. In this paper, we shall propose a new efficient handover authentication mechanism. The new mechanism offers a higher level of security on a more scalable ground with the client’s privacy better preserved. The results of our performance analysis suggest that our new mechanism is superior to some similar mechanisms in terms of authentication delay. PMID:27171160

  20. A New Ticket-Based Authentication Mechanism for Fast Handover in Mesh Network.

    PubMed

    Lai, Yan-Ming; Cheng, Pu-Jen; Lee, Cheng-Chi; Ku, Chia-Yi

    2016-01-01

    Due to the ever-growing popularity mobile devices of various kinds have received worldwide, the demands on large-scale wireless network infrastructure development and enhancement have been rapidly swelling in recent years. A mobile device holder can get online at a wireless network access point, which covers a limited area. When the client leaves the access point, there will be a temporary disconnection until he/she enters the coverage of another access point. Even when the coverages of two neighboring access points overlap, there is still work to do to make the wireless connection smoothly continue. The action of one wireless network access point passing a client to another access point is referred to as the handover. During handover, for security concerns, the client and the new access point should perform mutual authentication before any Internet access service is practically gained/provided. If the handover protocol is inefficient, in some cases discontinued Internet service will happen. In 2013, Li et al. proposed a fast handover authentication mechanism for wireless mesh network (WMN) based on tickets. Unfortunately, Li et al.'s work came with some weaknesses. For one thing, some sensitive information such as the time and date of expiration is sent in plaintext, which increases security risks. For another, Li et al.'s protocol includes the use of high-quality tamper-proof devices (TPDs), and this unreasonably high equipment requirement limits its applicability. In this paper, we shall propose a new efficient handover authentication mechanism. The new mechanism offers a higher level of security on a more scalable ground with the client's privacy better preserved. The results of our performance analysis suggest that our new mechanism is superior to some similar mechanisms in terms of authentication delay.

  1. Family-Joining: A Fast Distance-Based Method for Constructing Generally Labeled Trees

    PubMed Central

    Kalaghatgi, Prabhav; Pfeifer, Nico; Lengauer, Thomas

    2016-01-01

    The widely used model for evolutionary relationships is a bifurcating tree with all taxa/observations placed at the leaves. This is not appropriate if the taxa have been densely sampled across evolutionary time and may be in a direct ancestral relationship, or if there is not enough information to fully resolve all the branching points in the evolutionary tree. In this article, we present a fast distance-based agglomeration method called family-joining (FJ) for constructing so-called generally labeled trees in which taxa may be placed at internal vertices and the tree may contain polytomies. FJ constructs such trees on the basis of pairwise distances and a distance threshold. We tested three methods for threshold selection, FJ-AIC, FJ-BIC, and FJ-CV, which minimize Akaike information criterion, Bayesian information criterion, and cross-validation error, respectively. When compared with related methods on simulated data, FJ-BIC was among the best at reconstructing the correct tree across a wide range of simulation scenarios. FJ-BIC was applied to HIV sequences sampled from individuals involved in a known transmission chain. The FJ-BIC tree was found to be compatible with almost all transmission events. On average, internal branches in the FJ-BIC tree have higher bootstrap support than branches in the leaf-labeled bifurcating tree constructed using RAxML. 36% and 25% of the internal branches in the FJ-BIC tree and RAxML tree, respectively, have bootstrap support greater than 70%. To the best of our knowledge the method presented here is the first attempt at modeling evolutionary relationships using generally labeled trees. PMID:27436007

  2. Fast Dynamic Simulation-Based Small Signal Stability Assessment and Control

    SciTech Connect

    Acharya, Naresh; Baone, Chaitanya; Veda, Santosh; Dai, Jing; Chaudhuri, Nilanjan; Leonardi, Bruno; Sanches-Gasca, Juan; Diao, Ruisheng; Wu, Di; Huang, Zhenyu; Zhang, Yu; Jin, Shuangshuang; Zheng, Bin; Chen, Yousu

    2014-12-31

    Power grid planning and operation decisions are made based on simulation of the dynamic behavior of the system. Enabling substantial energy savings while increasing the reliability of the aging North American power grid through improved utilization of existing transmission assets hinges on the adoption of wide-area measurement systems (WAMS) for power system stabilization. However, adoption of WAMS alone will not suffice if the power system is to reach its full entitlement in stability and reliability. It is necessary to enhance predictability with "faster than real-time" dynamic simulations that will enable the dynamic stability margins, proactive real-time control, and improve grid resiliency to fast time-scale phenomena such as cascading network failures. Present-day dynamic simulations are performed only during offline planning studies, considering only worst case conditions such as summer peak, winter peak days, etc. With widespread deployment of renewable generation, controllable loads, energy storage devices and plug-in hybrid electric vehicles expected in the near future and greater integration of cyber infrastructure (communications, computation and control), monitoring and controlling the dynamic performance of the grid in real-time would become increasingly important. The state-of-the-art dynamic simulation tools have limited computational speed and are not suitable for real-time applications, given the large set of contingency conditions to be evaluated. These tools are optimized for best performance of single-processor computers, but the simulation is still several times slower than real-time due to its computational complexity. With recent significant advances in numerical methods and computational hardware, the expectations have been rising towards more efficient and faster techniques to be implemented in power system simulators. This is a natural expectation, given that the core solution algorithms of most commercial simulators were developed

  3. Fast increasing of surface ozone concentrations in Pearl River Delta characterized by a regional air quality monitoring network during 2006-2011.

    PubMed

    Li, Jinfeng; Lu, Keding; Lv, Wei; Li, Jun; Zhong, Liuju; Ou, Yubo; Chen, Duohong; Huang, Xin; Zhang, Yuanhang

    2014-01-01

    Based on the observation by a Regional Air Quality Monitoring Network including 16 monitoring stations, temporal and spatial variations of ozone (O3), NO2 and total oxidant (O(x)) were analyzed by both linear regression and cluster analysis. A fast increase of regional O3 concentrations of 0.86 ppbV/yr was found for the annual averaged values from 2006 to 2011 in Guangdong, China. Such fast O3 increase is accompanied by a correspondingly fast NO(x) reduction as indicated by a fast NO2 reduction rate of 0.61 ppbV/yr. Based on a cluster analysis, the monitoring stations were classified into two major categories--rural stations (non-urban) and suburban/urban stations. The O3 concentrations at rural stations were relatively conserved while those at suburban/urban stations showed a fast increase rate of 2.0 ppbV/yr accompanied by a NO2 reduction rate of 1.2 ppbV/yr. Moreover, a rapid increase of the averaged O3 concentrations in springtime (13%/yr referred to 2006 level) was observed, which may result from the increase of solar duration, reduction of precipitation in Guangdong and transport from Eastern Central China. Application of smog production algorithm showed that the photochemical O3 production is mainly volatile organic compounds (VOC)-controlled. However, the photochemical O3 production is sensitive to both NO(x) and VOC for O3 pollution episode. Accordingly, it is expected that a combined NO(x) and VOC reduction will be helpful for the reduction of the O3 pollution episodes in Pearl River Delta while stringent VOC emission control is in general required for the regional O3 pollution control.

  4. Biosensors based on surface plasmon-enhanced fluorescence spectroscopy.

    PubMed

    Dostálek, Jakub; Knoll, Wolfgang

    2008-09-01

    The implementation of surface plasmon-enhanced fluorescence spectroscopy (SPFS) to surface plasmon resonance (SPR) biosensors enables increasing their sensitivity by several orders of magnitude. In SPR-based biosensors, surface plasmons probe the binding of target molecules contained in a liquid sample by their affinity partners attached to a metallic sensor surface. SPR biosensors relying on the detection of refractive index changes allow for direct observation of the binding of large and medium size molecules that produces sufficiently large refractive index changes. In SPR biosensors exploiting SPFS, the capture of fluorophore-labeled molecules to the sensor surface is observed by the detection of fluorescence light emitted from the surface. This technique takes advantage of the enhanced intensity of electromagnetic field accompanied with the resonant excitation of surface plasmons. The interaction with surface plasmons can greatly increase the measured fluorescence signal through enhancing the excitation rate of fluorophores and by more efficient collecting of fluorescence light. SPFS-based biosensors were shown to enable the analysis of samples with extremely low analyte concentrations and the detection of small molecules. In this review, we describe the fundamental principles, implementations, and current state of the art applications of SPFS biosensors. This review focuses on SPFS-based biosensors employing the excitation of surface plasmons on continuous metal-dielectric interfaces.

  5. Fast-Running Aeroelastic Code Based on Unsteady Linearized Aerodynamic Solver Developed

    NASA Technical Reports Server (NTRS)

    Reddy, T. S. R.; Bakhle, Milind A.; Keith, T., Jr.

    2003-01-01

    The NASA Glenn Research Center has been developing aeroelastic analyses for turbomachines for use by NASA and industry. An aeroelastic analysis consists of a structural dynamic model, an unsteady aerodynamic model, and a procedure to couple the two models. The structural models are well developed. Hence, most of the development for the aeroelastic analysis of turbomachines has involved adapting and using unsteady aerodynamic models. Two methods are used in developing unsteady aerodynamic analysis procedures for the flutter and forced response of turbomachines: (1) the time domain method and (2) the frequency domain method. Codes based on time domain methods require considerable computational time and, hence, cannot be used during the design process. Frequency domain methods eliminate the time dependence by assuming harmonic motion and, hence, require less computational time. Early frequency domain analyses methods neglected the important physics of steady loading on the analyses for simplicity. A fast-running unsteady aerodynamic code, LINFLUX, which includes steady loading and is based on the frequency domain method, has been modified for flutter and response calculations. LINFLUX, solves unsteady linearized Euler equations for calculating the unsteady aerodynamic forces on the blades, starting from a steady nonlinear aerodynamic solution. First, we obtained a steady aerodynamic solution for a given flow condition using the nonlinear unsteady aerodynamic code TURBO. A blade vibration analysis was done to determine the frequencies and mode shapes of the vibrating blades, and an interface code was used to convert the steady aerodynamic solution to a form required by LINFLUX. A preprocessor was used to interpolate the mode shapes from the structural dynamic mesh onto the computational dynamics mesh. Then, we used LINFLUX to calculate the unsteady aerodynamic forces for a given mode, frequency, and phase angle. A postprocessor read these unsteady pressures and

  6. Sub 10 ns fast switching and resistance control in lateral GeTe-based phase-change memory

    NASA Astrophysics Data System (ADS)

    Yin, You; Zhang, Yulong; Takehana, Yousuke; Kobayashi, Ryota; Zhang, Hui; Hosaka, Sumio

    2016-06-01

    In this study, we investigated the fast switching and resistance control in a lateral GeTe-based phase-change memory (PCM). The resistivity of GeTe as a function of annealing temperature showed that it changed by more than 6 orders of magnitude in a very narrow temperature range. X-ray diffraction patterns of GeTe films indicated that GeTe had only one crystal structure, that is, face-centered cubic. It was demonstrated that the lateral device with a top conducting layer had a good performance. The operation characteristics of the GeTe-based lateral PCM device showed that it could be operated even when sub-10-ns voltage pulses were applied, making it much faster than a Ge2Sb2Te5-based device. The device resistance was successfully controlled by applying a staircase-like pulse, which enables the device to be used for fast multilevel storage.

  7. Graphene metamaterials based tunable terahertz absorber: effective surface conductivity approach.

    PubMed

    Andryieuski, Andrei; Lavrinenko, Andrei V

    2013-04-08

    In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity we investigate the properties of graphene wire medium and graphene fishnet metamaterials and demonstrate both narrowband and broadband tunable absorbers.

  8. Sensitivity measurement of a cantilever-based surface stress sensor

    NASA Astrophysics Data System (ADS)

    Haag, Ann-Lauriene; Schumacher, Zeno; Grutter, Peter

    2016-10-01

    A detailed analysis of the temporal surface stress evolution for potential-driven adsorption of ions is discussed. A gold-coated cantilever is used to simultaneously measure the change in surface stress as well as the current response during an applied potential step. In this electrochemical configuration, the cantilever acts as the working electrode, a platinum wire as the counter electrode, and the Ag/AgCl (sat. KCl) electrode as the reference electrode. To study the time-dependent signal and the sensitivity of the cantilever response, the frequency of the potential step applied to the cantilever is varied from 1 s to 0.1 ms. First, a comparison between a strong adsorbing (chloride Cl-) and a weak adsorbing ion (perchlorate ClO 4- ) in a 1 mM solution is presented. Next, the linear relationship between surface stress and charge density is measured for these fast potential steps. The slope of this fit is defined as the sensitivity of the system and is shown to increase for shorter potential pulses. Finally, the behaviour of the surface stress and current for consecutive applied potential steps is studied.

  9. Comprehensive physics-based compact model for fast p-i-n diode using MATLAB and Simulink

    NASA Astrophysics Data System (ADS)

    Xue, Peng; Fu, Guicui; Zhang, Dong

    2016-07-01

    In this study, a physics-based model for the fast p-i-n diode is proposed. The model is based on the 1-D Fourier-based solution of ambipolar diffusion equation (ADE) implemented in MATLAB and Simulink. The physical characteristics of fast diode design concepts such as local lifetime control (LLC), emitter control (EMCON) and deep field stop are taken into account. Based on these fast diode design concepts, the ADE is solved for all injection levels instead of high-level injection only as usually done. The variation of high-level lifetime due to local lifetime control is also included in the solution. With the deep field stop layer taken into consideration, the depletion behavior in the N-base during reverse recovery is redescribed. Some physical effects such as avalanche generation and carrier recombination in the depletion region are also taken into account. To be self contained, a parameter extraction method is proposed to extract all the parameters of the model. In the end, the static and reverse recovery experiments for a commercial EMCON diode and a LLC diode are used to validate the proposed model. The simulation results are compared with experiment results and good agreement is obtained.

  10. The differential algebra based multiple level fast multipole algorithm for 3D space charge field calculation and photoemission simulation

    SciTech Connect

    None, None

    2015-09-28

    Coulomb interaction between charged particles inside a bunch is one of the most importance collective effects in beam dynamics, becoming even more significant as the energy of the particle beam is lowered to accommodate analytical and low-Z material imaging purposes such as in the time resolved Ultrafast Electron Microscope (UEM) development currently underway at Michigan State University. In addition, space charge effects are the key limiting factor in the development of ultrafast atomic resolution electron imaging and diffraction technologies and are also correlated with an irreversible growth in rms beam emittance due to fluctuating components of the nonlinear electron dynamics. In the short pulse regime used in the UEM, space charge effects also lead to virtual cathode formation in which the negative charge of the electrons emitted at earlier times, combined with the attractive surface field, hinders further emission of particles and causes a degradation of the pulse properties. Space charge and virtual cathode effects and their remediation are core issues for the development of the next generation of high-brightness UEMs. Since the analytical models are only applicable for special cases, numerical simulations, in addition to experiments, are usually necessary to accurately understand the space charge effect. In this paper we will introduce a grid-free differential algebra based multiple level fast multipole algorithm, which calculates the 3D space charge field for n charged particles in arbitrary distribution with an efficiency of O(n), and the implementation of the algorithm to a simulation code for space charge dominated photoemission processes.

  11. The differential algebra based multiple level fast multipole algorithm for 3D space charge field calculation and photoemission simulation

    DOE PAGES

    None, None

    2015-09-28

    Coulomb interaction between charged particles inside a bunch is one of the most importance collective effects in beam dynamics, becoming even more significant as the energy of the particle beam is lowered to accommodate analytical and low-Z material imaging purposes such as in the time resolved Ultrafast Electron Microscope (UEM) development currently underway at Michigan State University. In addition, space charge effects are the key limiting factor in the development of ultrafast atomic resolution electron imaging and diffraction technologies and are also correlated with an irreversible growth in rms beam emittance due to fluctuating components of the nonlinear electron dynamics.more » In the short pulse regime used in the UEM, space charge effects also lead to virtual cathode formation in which the negative charge of the electrons emitted at earlier times, combined with the attractive surface field, hinders further emission of particles and causes a degradation of the pulse properties. Space charge and virtual cathode effects and their remediation are core issues for the development of the next generation of high-brightness UEMs. Since the analytical models are only applicable for special cases, numerical simulations, in addition to experiments, are usually necessary to accurately understand the space charge effect. In this paper we will introduce a grid-free differential algebra based multiple level fast multipole algorithm, which calculates the 3D space charge field for n charged particles in arbitrary distribution with an efficiency of O(n), and the implementation of the algorithm to a simulation code for space charge dominated photoemission processes.« less

  12. Rough surface scattering based on facet model

    NASA Technical Reports Server (NTRS)

    Khamsi, H. R.; Fung, A. K.; Ulaby, F. T.

    1974-01-01

    A model for the radar return from bare ground was developed to calculate the radar cross section of bare ground and the effect of the frequency averaging on the reduction of the variance of the return. It is shown that, by assuming that the distribution of the slope to be Gaussian and that the distribution of the length of the facet to be in the form of the positive side of a Gaussian distribution, the results are in good agreement with experimental data collected by an 8- to 18-GHz radar spectrometer system. It is also shown that information on the exact correlation length of the small structure on the ground is not necessary; an effective correlation length may be calculated based on the facet model and the wavelength of the incident wave.

  13. Femtosecond laser surface texturing of a nickel-based superalloy

    NASA Astrophysics Data System (ADS)

    Semaltianos, N. G.; Perrie, W.; French, P.; Sharp, M.; Dearden, G.; Watkins, K. G.

    2008-12-01

    Femtosecond laser (180 fs, 775 nm, 1 kHz) surface modification of the nickel-based superalloy C263 is investigated. The laser beam was scanned onto areas on the substrate with macroscopic dimensions using different fluences ( F = 0.28-30 J/cm 2), speeds ( υ = 1-10 mm/s) and number of overscans (5-90). The evolution of surface morphology, roughness, ablation depth and volume ablation rate with laser micromachining parameters were determined. The surface morphology is characterized by ripples for low average powers while for high average powers the surface becomes porous.

  14. Fast GPU-based Monte Carlo simulations for LDR prostate brachytherapy

    NASA Astrophysics Data System (ADS)

    Bonenfant, Éric; Magnoux, Vincent; Hissoiny, Sami; Ozell, Benoît; Beaulieu, Luc; Després, Philippe

    2015-07-01

    The aim of this study was to evaluate the potential of bGPUMCD, a Monte Carlo algorithm executed on Graphics Processing Units (GPUs), for fast dose calculations in permanent prostate implant dosimetry. It also aimed to validate a low dose rate brachytherapy source in terms of TG-43 metrics and to use this source to compute dose distributions for permanent prostate implant in very short times. The physics of bGPUMCD was reviewed and extended to include Rayleigh scattering and fluorescence from photoelectric interactions for all materials involved. The radial and anisotropy functions were obtained for the Nucletron SelectSeed in TG-43 conditions. These functions were compared to those found in the MD Anderson Imaging and Radiation Oncology Core brachytherapy source registry which are considered the TG-43 reference values. After appropriate calibration of the source, permanent prostate implant dose distributions were calculated for four patients and compared to an already validated Geant4 algorithm. The radial function calculated from bGPUMCD showed excellent agreement (differences within 1.3%) with TG-43 accepted values. The anisotropy functions at r = 1 cm and r = 4 cm were within 2% of TG-43 values for angles over 17.5°. For permanent prostate implants, Monte Carlo-based dose distributions with a statistical uncertainty of 1% or less for the target volume were obtained in 30 s or less for 1 × 1 × 1 mm3 calculation grids. Dosimetric indices were very similar (within 2.7%) to those obtained with a validated, independent Monte Carlo code (Geant4) performing the calculations for the same cases in a much longer time (tens of minutes to more than a hour). bGPUMCD is a promising code that lets envision the use of Monte Carlo techniques in a clinical environment, with sub-minute execution times on a standard workstation. Future work will explore the use of this code with an inverse planning method to provide a complete Monte Carlo-based planning solution.

  15. Fast GPU-based Monte Carlo simulations for LDR prostate brachytherapy.

    PubMed

    Bonenfant, Éric; Magnoux, Vincent; Hissoiny, Sami; Ozell, Benoît; Beaulieu, Luc; Després, Philippe

    2015-07-07

    The aim of this study was to evaluate the potential of bGPUMCD, a Monte Carlo algorithm executed on Graphics Processing Units (GPUs), for fast dose calculations in permanent prostate implant dosimetry. It also aimed to validate a low dose rate brachytherapy source in terms of TG-43 metrics and to use this source to compute dose distributions for permanent prostate implant in very short times. The physics of bGPUMCD was reviewed and extended to include Rayleigh scattering and fluorescence from photoelectric interactions for all materials involved. The radial and anisotropy functions were obtained for the Nucletron SelectSeed in TG-43 conditions. These functions were compared to those found in the MD Anderson Imaging and Radiation Oncology Core brachytherapy source registry which are considered the TG-43 reference values. After appropriate calibration of the source, permanent prostate implant dose distributions were calculated for four patients and compared to an already validated Geant4 algorithm. The radial function calculated from bGPUMCD showed excellent agreement (differences within 1.3%) with TG-43 accepted values. The anisotropy functions at r = 1 cm and r = 4 cm were within 2% of TG-43 values for angles over 17.5°. For permanent prostate implants, Monte Carlo-based dose distributions with a statistical uncertainty of 1% or less for the target volume were obtained in 30 s or less for 1 × 1 × 1 mm(3) calculation grids. Dosimetric indices were very similar (within 2.7%) to those obtained with a validated, independent Monte Carlo code (Geant4) performing the calculations for the same cases in a much longer time (tens of minutes to more than a hour). bGPUMCD is a promising code that lets envision the use of Monte Carlo techniques in a clinical environment, with sub-minute execution times on a standard workstation. Future work will explore the use of this code with an inverse planning method to provide a complete Monte Carlo-based planning solution.

  16. Metal Optics Based nanoLEDs: In Search of a Fast, Efficient, Nanoscale Light Emitter

    NASA Astrophysics Data System (ADS)

    Eggleston, Michael Scott

    Since the invention of the laser, stimulated emission has been the de facto king of optical communication. Lasers can be directly modulated at rates as high as 50GHz, much faster than a typical solid state light-emitting diode (LED) that is limited by spontaneous emission to <1GHz. Unfortunately, lasers have a severe scaling problem; they require large cavities operated at high power to achieve efficient lasing. A properly designed LED can be made arbitrarily small and still operate with high-efficiency. On-chip interconnects is an area that is in desperate need of a high-speed, low-power optical emitter that can enable on-chip links to replace current high-loss metal wires. In this work, I will show that by utilizing proper antenna design, a nanoLED can be created that is faster than a laser while still operating at >50% efficiency. I start by formulating an optical antenna circuit model whose elements are based completely off of antenna geometry. This allows for intuitive antenna design and suggests that rate enhancements up to ~3,000x are possible while keeping antenna efficiency >50%. Such a massive speed-up in spontaneous emission would enable an LED that can be directly modulated at 100's of GHz, much faster than any laser. I then use the circuit model to design an arch-dipole antenna, a dipole antenna with an inductive arch across the feedgap. I experimentally demonstrate a free-standing arch-dipole based nanoLED with rate enhancement of 115x and 66% antenna efficiency. Because the emitter is InGaAsP, a common III-V material, I experimentally show that this device can be easily and efficiently coupled into an InP waveguide. Experimental coupling efficiencies up to 70% are demonstrated and directional antennas are employed that offer front to back emission ratios of 3:1. Finally, I show that a nanoLED can still have high quantum yield by using a transition metal dichalcogenide, WSe2, as the emitter material. By coupling a monolayer of WSe2 to a cavity

  17. A surface-acoustic-wave-based cantilever bio-sensor.

    PubMed

    De Simoni, Giorgio; Signore, Giovanni; Agostini, Matteo; Beltram, Fabio; Piazza, Vincenzo

    2015-06-15

    A scalable surface-acoustic-wave- (SAW-) based cantilevered device for portable bio-chemical sensing applications is presented. Even in the current, proof-of-principle implementation this architecture is shown to outperform commercial quartz-crystal microbalances in terms of sensitivity. Adhesion of analytes on a functionalized surface of the cantilever shifts the resonant frequency of a SAW-generating transducer due to the stress-induced variation of the speed of surface acoustic modes. We discuss the relevance of this approach for diagnostics applications based on miniaturized devices.

  18. Engineered surface Bloch waves in graphene-based hyperbolic metamaterials.

    PubMed

    Xiang, Yuanjiang; Guo, Jun; Dai, Xiaoyu; Wen, Shuangchun; Tang, Dingyuan

    2014-02-10

    A kind of tunable hyperbolic metamaterial (HMM) based on the graphene-dielectric layered structure at near-infrared frequencies is presented, and the engineered surface Bloch waves between graphene-based HMM and isotropic medium are investigated. Our calculations demonstrate that the frequency and frequency range of surface Bloch waves existence can be tuned by varying the Fermi energy of graphene sheets via electrostatic biasing. Moreover, we show that the frequency range of surface Bloch waves existence can be broadened by decreasing the thickness of the dielectric in the graphene-dielectric layered structure or by increasing the layer number of graphene sheets.

  19. Surface plasmon enhanced photodetectors based on internal photoemission

    NASA Astrophysics Data System (ADS)

    Alavirad, Mohammad; Roy, Langis; Berini, Pierre

    2016-10-01

    Surface plasmon photodetectors are of broad interest. They are promising for several applications including telecommunications, photovoltaic solar cells, photocatalysis, color-sensitive detection, and sensing, as they can provide highly enhanced fields and strong confinement (to subwavelength scales). Such photodetectors typically combine a nanometallic structure that supports surface plasmons with a photodetection structure based on internal photoemission or electron-hole pair creation. Photodetector architectures are highly varied, including waveguides, gratings, nanoparticles, nanoislands, or nanoantennas. We review the operating principles behind surface plasmon photodetectors based on the internal photoelectric effect, and we survey and compare the most recent and leading edge concepts reported in the literature.

  20. A novel Fast Gas Chromatography based technique for higher time resolution measurements of speciated monoterpenes in air

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Kato, S.; Nakashima, Y.; Kajii, Y.

    2013-12-01

    Biogenic emissions supply the largest fraction of non-methane volatile organic compounds (VOC) from the biosphere to the atmospheric boundary layer, and typically comprise a complex mixture of reactive terpenes. Due to this chemical complexity, achieving comprehensive measurements of biogenic VOC (BVOC) in air within a satisfactory time resolution is analytically challenging. To address this, we have developed a novel, fully automated Fast Gas Chromatography (Fast-GC) based technique to provide higher time resolution monitoring of monoterpenes (and selected other C9-C15 terpenes) during plant emission studies and in ambient air. To our knowledge, this is the first study to apply a Fast-GC based separation technique to achieve quantification of terpenes in air. Three chromatography methods have been developed for atmospheric terpene analysis under different sampling scenarios. Each method facilitates chromatographic separation of selected BVOC within a significantly reduced analysis time compared to conventional GC methods, whilst maintaining the ability to quantify individual monoterpene structural isomers. Using this approach, the C10-C15 BVOC composition of single plant emissions may be characterised within a ~ 14 min analysis time. Moreover, in situ quantification of 12 monoterpenes in unpolluted ambient air may be achieved within an ~ 11 min chromatographic separation time (increasing to ~ 19 min when simultaneous quantification of multiple oxygenated C9-C10 terpenoids is required, and/or when concentrations of anthropogenic VOC are significant). This corresponds to a two- to fivefold increase in measurement frequency compared to conventional GC methods. Here we outline the technical details and analytical capability of this chromatographic approach, and present the first in situ Fast-GC observations of 6 monoterpenes and the oxygenated BVOC linalool in ambient air. During this field deployment within a suburban forest ~ 30 km west of central Tokyo, Japan, the

  1. Fast set-based association analysis using summary data from GWAS identifies novel gene loci for human complex traits

    PubMed Central

    Bakshi, Andrew; Zhu, Zhihong; Vinkhuyzen, Anna A. E.; Hill, W. David; McRae, Allan F.; Visscher, Peter M.; Yang, Jian

    2016-01-01

    We propose a method (fastBAT) that performs a fast set-based association analysis for human complex traits using summary-level data from genome-wide association studies (GWAS) and linkage disequilibrium (LD) data from a reference sample with individual-level genotypes. We demonstrate using simulations and analyses of real datasets that fastBAT is more accurate and orders of magnitude faster than the prevailing methods. Using fastBAT, we analyze summary data from the latest meta-analyses of GWAS on 150,064–339,224 individuals for height, body mass index (BMI), and schizophrenia. We identify 6 novel gene loci for height, 2 for BMI, and 3 for schizophrenia at PfastBAT < 5 × 10−8. The gain of power is due to multiple small independent association signals at these loci (e.g. the THRB and FOXP1 loci for schizophrenia). The method is general and can be applied to GWAS data for all complex traits and diseases in humans and to such data in other species. PMID:27604177

  2. Analysis of Fast-Scale Bifurcation in Peak Current Controlled Buck-Boost Inverter Based on Unified Averaged Model

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Dong, Shuai; Guan, Weimin; Liu, Ye

    In this paper, a unified averaged modeling method is proposed to investigate the fast-scale period-doubling bifurcation of a full-bridge integrated buck-boost inverter with peak current control. In order to increase the resolution of the conventional classic averaged model to half the switching frequency, sample-and-hold effect of inductor current is absorbed into the averaged model, i.e. the proposed unified averaged model can capture the high-frequency dynamical characteristics of the buck-boost inverter, which is both an extension and a modification of conventional averaged model. Based on the unified mode, fast-scale bifurcation is identified, and the corresponding bifurcation point is predicted with the help of the locus movement of all the poles, and their underlying mechanisms are revealed. Detailed analysis shows that the occurrence of high-frequency oscillation means fast-scale bifurcation, while the occurrence of low-frequency oscillation leads to slow-scale bifurcation. Finally, it is demonstrated that the unified averaged model can provide not only a general method to investigate both the slow- and fast-scale bifurcations in a unified framework but also a quite straightforward design-oriented method which can be directly applicable.

  3. A real-time surface inspection system for precision steel balls based on machine vision

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Ji; Tsai, Jhy-Cherng; Hsu, Ya-Chen

    2016-07-01

    Precision steel balls are one of the most fundament components for motion and power transmission parts and they are widely used in industrial machinery and the automotive industry. As precision balls are crucial for the quality of these products, there is an urgent need to develop a fast and robust system for inspecting defects of precision steel balls. In this paper, a real-time system for inspecting surface defects of precision steel balls is developed based on machine vision. The developed system integrates a dual-lighting system, an unfolding mechanism and inspection algorithms for real-time signal processing and defect detection. The developed system is tested under feeding speeds of 4 pcs s-1 with a detection rate of 99.94% and an error rate of 0.10%. The minimum detectable surface flaw area is 0.01 mm2, which meets the requirement for inspecting ISO grade 100 precision steel balls.

  4. A fast initial alignment of MIMU in the two-dimension trajectory correction fuze for spinning projectile on stationary base

    NASA Astrophysics Data System (ADS)

    Wang, Qin; Li, Shi-yi; Xiao, Hong-bing; Li, Hu-quan

    2008-03-01

    In the paper, a fast initial alignment of strapdown MIMU used in the two-dimension trajectory correction fuze was analyzed. According to the situation that MIMU can't work normally because of high shock on shrapnel of Compound Extended Range by Base Bleed and Rocket at firing, the MIMU in initial alignment with Bar-Itzhack and Berman's error model is presented and the observability was analyzed. It shows that the observability of MIMU on stationary base is poor. The selection of unobservable states was discussed. A Kalman filter estimation algorithm was provided, but the azimuth error converges very slowly in initial alignment. A fast estimation method of the azimuth error was proposed. It reveals that the azimuth error can be entirely estimated from the estimates of leveling error and leveling error rate without gyro output signal. It shows that the method can realize the rapid initial alignment of MIMU.

  5. Separation and concentration of natural products by fast forced adsorption using well-dispersed velvet-like graphitic carbon nitride with response surface methodology optimisation.

    PubMed

    Ding, Xinru; Zhu, Jun; Zhang, Yue; Xia, Qian; Bi, Wentao; Yang, Xiaodi; Yang, Jinfei

    2016-07-01

    Well-dispersed velvet-like graphitic carbon nitride nanoparticles with a large surface area were prepared and utilized for separation and concentration of bioactive compounds from fruit extracts by fast (20s) forced adsorption. The large surface area, enhanced non-covalent interactions of this nanoparticle with bioactive compounds and good dispersity in different solvents benefited its application as a good sorbent. To evaluate their adsorption capabilities, these carbon nitride nanoparticles were used for separation and concentration of flavonoids from fruit extracts by a forced-adsorption dispersive solid phase extraction method. The combined use of this nanoparticle and our experimental conditions showed excellent precision (3.6-4.7%) and sensitivity (limits of detection (S/N=3): 0.6-3.75ng/mL). This research provides an alternative strategy to prepare suitable sorbents for adsorption, separation and concentration of various compounds from different extracts.

  6. Development of fast disintegrating compressed tablets using amino acid as disintegration accelerator: evaluation of wetting and disintegration of tablet on the basis of surface free energy.

    PubMed

    Fukami, Jinichi; Ozawa, Asuka; Yoshihashi, Yasuo; Yonemochi, Etsuo; Terada, Katsuhide

    2005-12-01

    A fast disintegrating compressed tablet was formulated using amino acids, such as L-lysine HCl, L-alanine, glycine and L-tyrosine as disintegration accelerator. The tablets having the hardness of about 4 kgf were prepared and the effect of amino acids on the wetting time and disintegration time in the oral cavity of tablets was examined on the basis of surface free energy of amino acids. The wetting time of the tablets increased in the order of L-lysine HCl, L-alanine, glycine and L-tyrosine, whereas the disintegration time in the oral cavity of the tablets increased in the order of L-alanine, glycine, L-lysine HCl and L-tyrosine. These behaviors were well analyzed by the introduction of surface free energy. When the polar component of amino acid was large value or the dispersion component was small value, faster wetting of tablet was observed. When the dispersion component of amino acid was large value or the dispersion component was small value, faster disintegration of tablet was observed, expect of L-tyrosine tablet. The fast disintegration of tablets was explained by the theory presented by Matsumaru.

  7. SDIX RapidChek Listeria F.A.S.T. environmental test system for the detection of Listeria species on environmental surfaces.

    PubMed

    Muldoon, Mark T; Allen, Ann-Christine Olsson; Gonzalez, Vera; Sutzko, Meredith; Klaus, Lindpaintner

    2012-01-01

    The SDIX RapidChek Listeria F.A.S.T. test system was validated against the U.S. Department of Agriculture-Food Safety and Inspection Service (USDA-FSIS) cultural reference method for the detection of Listeria species on stainless steel, plastic, rubber, and painted concrete. The SDIX method uses a proprietary RapidChek Listeria enrichment media for a one-step, 24-40 h enrichment at 30 degrees C, and detects Listeria on an immunochromatographic lateral flow device in 10 min. Different Listeria species were used to spike each of the environmental surfaces. Environmental surfaces were spiked at levels ranging from 50 to 400 CFU/surface (1 in.2 swabs for painted concrete, 4 in.(2) for sponge). A total of 120 spiked samples were tested by the SDIX method at 24 and 40 h and the cultural reference method. Total confirmed positives were 49, 54, and 48 for the SDIX 24 h method, the SDIX 40 h method, and the USDA-FSIS cultural reference method, respectively. Nonspiked samples from all environmental surfaces were reported as negative for Listeria spp. by all methods. The overall Chi square was 0.017 (P = 0.104) and 0.611 (P= 0.566) after a 24 and 40 h enrichment, respectively, indicating that the test method was equivalent in performance to the reference method at both enrichment times. The SDIX method was evaluated for the detection of 50 Listeria and 35 non-Listeria bacterial strains. All 50 Listeria strains were detected by the method (100% sensitivity). Five out of 35 non-Listeria species gave light test signals when grown in nonselective broth culture and tested undiluted. However, when grown in the RapidChek Listeria F.A.S.T. proprietary media, only one bacterial strain (Staphylococcus aureus) was detected, giving a very low test signal (97% specificity). The method was shown to be robust toward several alterations in testing and storage conditions.

  8. Sugar Surfactant Based Microemulsions at Solid Surfaces: Influence of the Oil Type and Surface Polarity.

    PubMed

    Vargas-Ruiz, Salomé; Soltwedel, Olaf; Micciulla, Samantha; Sreij, Ramsia; Feoktystov, Artem; von Klitzing, Regine; Hellweg, Thomas; Wellert, Stefan

    2016-11-15

    The structure of sugar-surfactant-based bicontinuous microemulsions in the bulk and at hydrophilic and hydrophobic solid planar surfaces was studied by means of neutron scattering techniques (SANS, NR, and GISANS). In particular, the influence of the type of oil (tetradecane and methyl oleate) on the structural properties in the vicinity of surfaces was investigated at different oil-to-water ratios. In the case of hydrophilic surfaces, the analysis of the scattering length density profiles reveals an induced ordering of the oil and water domains perpendicular to the solid-liquid interface in both sets of microemulsions. At hydrophobic surfaces, differences in the near-surface ordering between microemulsions containing polar and nonpolar oils are observed.

  9. Acid-base bifunctional catalytic surfaces for nucleophilic addition reactions.

    PubMed

    Motokura, Ken; Tada, Mizuki; Iwasawa, Yasuhiro

    2008-09-01

    This article illustrates the modification of oxide surfaces with organic amine functional groups to create acid-base bifunctional catalysts, summarizing our previous reports and also presenting new data. Immobilization of organic amines as bases on inorganic solid-acid surfaces afforded highly active acid-base bifunctional catalysts, which enabled various organic transformations including C--C coupling reactions, though these reactions did not proceed with either the homogeneous amine precursors or the acidic supports alone. Spectroscopic characterization, such as by solid-state MAS NMR and FTIR, revealed not only the interactions between acidic and basic sites but also bifunctional catalytic reaction mechanisms.

  10. Combining scale-space and similarity-based aspect graphs for fast 3D object recognition.

    PubMed

    Ulrich, Markus; Wiedemann, Christian; Steger, Carsten

    2012-10-01

    This paper describes an approach for recognizing instances of a 3D object in a single camera image and for determining their 3D poses. A hierarchical model is generated solely based on the geometry information of a 3D CAD model of the object. The approach does not rely on texture or reflectance information of the object's surface, making it useful for a wide range of industrial and robotic applications, e.g., bin-picking. A hierarchical view-based approach that addresses typical problems of previous methods is applied: It handles true perspective, is robust to noise, occlusions, and clutter to an extent that is sufficient for many practical applications, and is invariant to contrast changes. For the generation of this hierarchical model, a new model image generation technique by which scale-space effects can be taken into account is presented. The necessary object views are derived using a similarity-based aspect graph. The high robustness of an exhaustive search is combined with an efficient hierarchical search. The 3D pose is refined by using a least-squares adjustment that minimizes geometric distances in the image, yielding a position accuracy of up to 0.12 percent with respect to the object distance, and an orientation accuracy of up to 0.35 degree in our tests. The recognition time is largely independent of the complexity of the object, but depends mainly on the range of poses within which the object may appear in front of the camera. For efficiency reasons, the approach allows the restriction of the pose range depending on the application. Typical runtimes are in the range of a few hundred ms.

  11. A fast nonlinear conjugate gradient based method for 3D concentrated frictional contact problems

    NASA Astrophysics Data System (ADS)

    Zhao, Jing; Vollebregt, Edwin A. H.; Oosterlee, Cornelis W.

    2015-05-01

    This paper presents a fast numerical solver for a nonlinear constrained optimization problem, arising from 3D concentrated frictional shift and rolling contact problems with dry Coulomb friction. The solver combines an active set strategy with a nonlinear conjugate gradient method. One novelty is to consider the tractions of each slip element in a polar coordinate system, using azimuth angles as variables instead of conventional traction variables. The new variables are scaled by the diagonal of the underlying Jacobian. The fast Fourier transform (FFT) technique accelerates all matrix-vector products encountered, exploiting the matrix' Toeplitz structure. Numerical tests demonstrate a significant reduction of the computational time compared to existing solvers for concentrated contact problems.

  12. New, dense, and fast scintillators based on rare-earth tantalo-niobates

    NASA Astrophysics Data System (ADS)

    Voloshyna, O. V.; Boiaryntseva, I. A.; Baumer, V. N.; Ivanov, A. I.; Korjik, M. V.; Sidletskiy, O. Ts.

    2014-11-01

    Samples of undoped yttrium and gadolinium tantalo-niobates with common formulae RE(NbxTa1-x)O4, where RE=Y or Gd and x=0-1, have been obtained by solid-state reaction. Systematic study of structural, luminescent, and scintillation properties of these compounds was carried out. Lattice parameters and space groups of the mixed compounds were identified. UV- and X-ray luminescence spectra, as well as relative light outputs and scintillation decay times are measured. Gadolinium tantalo-niobate with the formulae GdNb0.2Ta0.8O4 showed the light output around 13 times larger than PbWO4 and fast decay with time constant 12 ns without additional slow component. Gadolinium tantalo-niobates may be considered as promising materials for high energy physics due to extremely high density, substantial light output, and fast decay.

  13. Ground-based complex for detection and investigation of fast optical transients in wide field

    NASA Astrophysics Data System (ADS)

    Molinari, Emilio; Beskin, Grigory; Bondar, Sergey; Karpov, Sergey; Plokhotnichenko, Vladimir; de-Bur, Vjacheslav; Greco, Guiseppe; Bartolini, Corrado; Guarnieri, Adriano; Piccioni, Adalberto

    2008-07-01

    To study short stochastic optical flares of different objects (GRBs, SNs, etc) of unknown localizations as well as NEOs it is necessary to monitor large regions of sky with high time resolution. We developed a system which consists of wide-field camera (FOW is 400-600 sq.deg.) using TV-CCD with time resolution of 0.13 s to record and classify optical transients, and a fast robotic telescope aimed to perform their spectroscopic and photometric investigation just after detection. Such two telescope complex TORTOREM combining wide-field camera TORTORA and robotic telescope REM operated from May 2006 at La Silla ESO observatory. Some results of its operation, including first fast time resolution study of optical transient accompanying GRB and discovery of its fine time structure, are presented. Prospects for improving the complex efficiency are given.

  14. Algorithms and applications of aberration correction and American standard-based digital evaluation in surface defects evaluating system

    NASA Astrophysics Data System (ADS)

    Wu, Fan; Cao, Pin; Yang, Yongying; Li, Chen; Chai, Huiting; Zhang, Yihui; Xiong, Haoliang; Xu, Wenlin; Yan, Kai; Zhou, Lin; Liu, Dong; Bai, Jian; Shen, Yibing

    2016-11-01

    The inspection of surface defects is one of significant sections of optical surface quality evaluation. Based on microscopic scattering dark-field imaging, sub-aperture scanning and stitching, the Surface Defects Evaluating System (SDES) can acquire full-aperture image of defects on optical elements surface and then extract geometric size and position information of defects with image processing such as feature recognization. However, optical distortion existing in the SDES badly affects the inspection precision of surface defects. In this paper, a distortion correction algorithm based on standard lattice pattern is proposed. Feature extraction, polynomial fitting and bilinear interpolation techniques in combination with adjacent sub-aperture stitching are employed to correct the optical distortion of the SDES automatically in high accuracy. Subsequently, in order to digitally evaluate surface defects with American standard by using American military standards MIL-PRF-13830B to judge the surface defects information obtained from the SDES, an American standard-based digital evaluation algorithm is proposed, which mainly includes a judgment method of surface defects concentration. The judgment method establishes weight region for each defect and adopts the method of overlap of weight region to calculate defects concentration. This algorithm takes full advantage of convenience of matrix operations and has merits of low complexity and fast in running, which makes itself suitable very well for highefficiency inspection of surface defects. Finally, various experiments are conducted and the correctness of these algorithms are verified. At present, these algorithms have been used in SDES.

  15. Defects detection for rough magnetic tiles surface based on light sectioning

    NASA Astrophysics Data System (ADS)

    Wang, Yuwei; Tao, Jiayuan; Chen, Xiangcheng; Wang, Keyi

    2016-09-01

    Magnetic tile as a kind of product of mass production and wide application in electronic motors, and defects detection is a major issue in its production line. In this paper, a machine vision method based on black-stripe projection is presented to deal with this issue. Because of magnetic tile surface with black colors, rough structure and complex grinding textures, we abandon intensity imaging and resort to light sectioning methods which provides more reliable and abundant surface information. In order to suppress the speckle diffraction effect caused by laser light source, we used the light-emitting diode (LED) with incoherent characteristics. The black-stripe images were captured by a high-speed camera. A fast algorithm was developed to extract and compare both edges of the black-stripe, which could detect defects and eliminate the effects of vibrations. The experimental results show that the simple and fast processing method proposed in this paper can detect the structural defects such as micro pits and micro cracks.

  16. Contour-Based Surface Reconstruction using MPU Implicit Models.

    PubMed

    Braude, Ilya; Marker, Jeffrey; Museth, Ken; Nissanov, Jonathan; Breen, David

    2007-03-01

    This paper presents a technique for creating a smooth, closed surface from a set of 2D contours, which have been extracted from a 3D scan. The technique interprets the pixels that make up the contours as points in ℝ(3) and employs Multi-level Partition of Unity (MPU) implicit models to create a surface that approximately fits to the 3D points. Since MPU implicit models additionally require surface normal information at each point, an algorithm that estimates normals from the contour data is also described. Contour data frequently contains noise from the scanning and delineation process. MPU implicit models provide a superior approach to the problem of contour-based surface reconstruction, especially in the presence of noise, because they are based on adaptive implicit functions that locally approximate the points within a controllable error bound. We demonstrate the effectiveness of our technique with a number of example datasets, providing images and error statistics generated from our results.

  17. A novel multi-aperture based sun sensor based on a fast multi-point MEANSHIFT (FMMS) algorithm.

    PubMed

    You, Zheng; Sun, Jian; Xing, Fei; Zhang, Gao-Fei

    2011-01-01

    With the current increased widespread interest in the development and applications of micro/nanosatellites, it was found that we needed to design a small high accuracy satellite attitude determination system, because the star trackers widely used in large satellites are large and heavy, and therefore not suitable for installation on micro/nanosatellites. A Sun sensor + magnetometer is proven to be a better alternative, but the conventional sun sensor has low accuracy, and cannot meet the requirements of the attitude determination systems of micro/nanosatellites, so the development of a small high accuracy sun sensor with high reliability is very significant. This paper presents a multi-aperture based sun sensor, which is composed of a micro-electro-mechanical system (MEMS) mask with 36 apertures and an active pixels sensor (APS) CMOS placed below the mask at a certain distance. A novel fast multi-point MEANSHIFT (FMMS) algorithm is proposed to improve the accuracy and reliability, the two key performance features, of an APS sun sensor. When the sunlight illuminates the sensor, a sun spot array image is formed on the APS detector. Then the sun angles can be derived by analyzing the aperture image location on the detector via the FMMS algorithm. With this system, the centroid accuracy of the sun image can reach 0.01 pixels, without increasing the weight and power consumption, even when some missing apertures and bad pixels appear on the detector due to aging of the devices and operation in a harsh space environment, while the pointing accuracy of the single-aperture sun sensor using the conventional correlation algorithm is only 0.05 pixels.

  18. A Novel Multi-Aperture Based Sun Sensor Based on a Fast Multi-Point MEANSHIFT (FMMS) Algorithm

    PubMed Central

    You, Zheng; Sun, Jian; Xing, Fei; Zhang, Gao-Fei

    2011-01-01

    With the current increased widespread interest in the development and applications of micro/nanosatellites, it was found that we needed to design a small high accuracy satellite attitude determination system, because the star trackers widely used in large satellites are large and heavy, and therefore not suitable for installation on micro/nanosatellites. A Sun sensor + magnetometer is proven to be a better alternative, but the conventional sun sensor has low accuracy, and cannot meet the requirements of the attitude determination systems of micro/nanosatellites, so the development of a small high accuracy sun sensor with high reliability is very significant. This paper presents a multi-aperture based sun sensor, which is composed of a micro-electro-mechanical system (MEMS) mask with 36 apertures and an active pixels sensor (APS) CMOS placed below the mask at a certain distance. A novel fast multi-point MEANSHIFT (FMMS) algorithm is proposed to improve the accuracy and reliability, the two key performance features, of an APS sun sensor. When the sunlight illuminates the sensor, a sun spot array image is formed on the APS detector. Then the sun angles can be derived by analyzing the aperture image location on the detector via the FMMS algorithm. With this system, the centroid accuracy of the sun image can reach 0.01 pixels, without increasing the weight and power consumption, even when some missing apertures and bad pixels appear on the detector due to aging of the devices and operation in a harsh space environment, while the pointing accuracy of the single-aperture sun sensor using the conventional correlation algorithm is only 0.05 pixels. PMID:22163770

  19. Computer-Based Video Instruction to Teach Students with Intellectual Disabilities to Verbally Respond to Questions and Make Purchases in Fast Food Restaurants

    ERIC Educational Resources Information Center

    Mechling, Linda C.; Pridgen, Leslie S.; Cronin, Beth A.

    2005-01-01

    Computer-based video instruction (CBVI) was used to teach verbal responses to questions presented by cashiers and purchasing skills in fast food restaurants. A multiple probe design across participants was used to evaluate the effectiveness of CBVI. Instruction occurred through simulations of three fast food restaurants on the computer using video…

  20. Fast mode decision based on human noticeable luminance difference and rate distortion cost for H.264/AVC

    NASA Astrophysics Data System (ADS)

    Li, Mian-Shiuan; Chen, Mei-Juan; Tai, Kuang-Han; Sue, Kuen-Liang

    2013-12-01

    This article proposes a fast mode decision algorithm based on the correlation of the just-noticeable-difference (JND) and the rate distortion cost (RD cost) to reduce the computational complexity of H.264/AVC. First, the relationship between the average RD cost and the number of JND pixels is established by Gaussian distributions. Thus, the RD cost of the Inter 16 × 16 mode is compared with the predicted thresholds from these models for fast mode selection. In addition, we use the image content, the residual data, and JND visual model for horizontal/vertical detection, and then utilize the result to predict the partition in a macroblock. From the experimental results, a greater time saving can be achieved while the proposed algorithm also maintains performance and quality effectively.

  1. GPU-accelerated non-uniform fast Fourier transform-based compressive sensing spectral domain optical coherence tomography.

    PubMed

    Xu, Daguang; Huang, Yong; Kang, Jin U

    2014-06-16

    We implemented the graphics processing unit (GPU) accelerated compressive sensing (CS) non-uniform in k-space spectral domain optical coherence tomography (SD OCT). Kaiser-Bessel (KB) function and Gaussian function are used independently as the convolution kernel in the gridding-based non-uniform fast Fourier transform (NUFFT) algorithm with different oversampling ratios and kernel widths. Our implementation is compared with the GPU-accelerated modified non-uniform discrete Fourier transform (MNUDFT) matrix-based CS SD OCT and the GPU-accelerated fast Fourier transform (FFT)-based CS SD OCT. It was found that our implementation has comparable performance to the GPU-accelerated MNUDFT-based CS SD OCT in terms of image quality while providing more than 5 times speed enhancement. When compared to the GPU-accelerated FFT based-CS SD OCT, it shows smaller background noise and less side lobes while eliminating the need for the cumbersome k-space grid filling and the k-linear calibration procedure. Finally, we demonstrated that by using a conventional desktop computer architecture having three GPUs, real-time B-mode imaging can be obtained in excess of 30 fps for the GPU-accelerated NUFFT based CS SD OCT with frame size 2048(axial) × 1,000(lateral).

  2. Modular surface functionalization of polyisobutylene-based biomaterials

    NASA Astrophysics Data System (ADS)

    Alvarez Albarran, Alejandra

    Polyisobutylene (PIB) has a unique combination of properties including chemical/oxidative resistance, low Tg (˜70 °C) and hydrophobicity. 1 PIB-based materials have also been found to have excellent biocompatibility and biostability: a PIB-based triblock copolymer thermoplastic elastomer (TPE) [poly(styrene-b-isobutylene-b-styrene)] (SIBS) is FDA-approved as a drug eluting coating for coronary stents.2 A new generation of PIB-based TPEs, with an arborescent or tree-like core (arbPIB) and plastic phases composed of blocks of polystyrene or poly(p-methyl styrene) (MS) has been developed in Professor Puskas group. These materials display unique TPE properties to make them very attractive for biomedical applications.3 The biocompatibility of these novel block copolymers has already been demonstrated in vitro and in vivo in rabbits.4. The Puskas group proposed to modify the surface properties of PIB-based TPEs using a modular approach. Using this approach it is possible to modify the surface chemistry and topology independently. The surface chemistry can be modified by "gluing" low molecular weight functionalized PIBs (PIB-X) to the surface of the TPEs. This "modular" approach will give unprecedented control over surface chemistry and topology and will contribute to new fundamental understanding of the effects of surface properties on the biocompatibility of polymeric materials. In this work PIB with a primary hydroxy head group (HO-PIB) was made in situ by living carbocationic polymerization using propylene oxide as initiator and titanium tetrachloride (TiCl4 ) as coinitiator. PIB functionalized with non-fouling moieties (PIB-X) was then synthesized from HO-PIB using Candida antarctica Lipase B (CALB) as enzymatic catalyst and spin coated onto the surface of the TPE. Protein adsorption studies using Surface Plasmon Resonance (SPR) demonstrated decreased fibrinogen (Fg) adsorption to the modified surface. XPS analyses provided clear evidence of the effectiveness of

  3. Microwave surface resistance in Tl-based superconducting thin films

    SciTech Connect

    Chang, L.D.; Moskowitz, M.J.; Hammond, R.B.; Eddy, M.M.; Olson, W.L.; Casavant, D.D.; Smith, E.J.; Robinson, M. ); Drabeck, L.; Gruner, G.; and others

    1989-09-25

    We report measurements of microwave surface resistance in Tl-based superconductor thin films made by laser ablation followed by a post-deposition thermal process. The films were measured by using cavity methods. The data at 9.5 and 148 GHz indicate that the residual resistance scales as {ital f}{sup 2}. At 77 K, the 9.5 GHz surface resistance is ten times smaller than oxygen-free high-conductance copper at the same temperature and frequency. The 9.5 GHz measurement also indicates that the film-substrate interface does not cause more microwave loss than the film surface.

  4. Microwave surface resistance in Tl-based superconducting thin films

    SciTech Connect

    Chang, L.D.; Moskowitz, M.J.; Hammond, R.B.; Eddy, M.M.; Olson, W.L.

    1989-09-25

    Measurements are reported of microwave surface resistance in Tl-based superconductor thin films made by laser ablation followed by a post-deposition thermal process. The films were measured by using cavity methods. The data at 9.5 and 148 GHz indicate that the residual resistance scales as f2. At 77 K, the 9.5 GHz surface resistance is ten times smaller than oxygen-free high-conductance copper at the same temperature and frequency. The 9.5 GHz measurement also indicates that the film-substrate interface does not cause more microwave loss than the film surface.

  5. Antimicrobial Contact-Active Oligo(2-oxazoline)s-Grafted Surfaces for Fast Water Disinfection at the Point-of-Use.

    PubMed

    Correia, Vanessa G; Ferraria, Ana M; Pinho, Mariana G; Aguiar-Ricardo, Ana

    2015-12-14

    Water is one of the most valuable resources today and its purity is crucial to health and society well-being. The access to safe drinking water is decreasing in the world, which can have a huge socio-economic impact especially in developing countries, more prone to water-associated diseases. The goal of this work was to develop an innovative, fast, and cost-effective 3D material capable of decontaminating water. We have used an eco-friendly strategy, combining plasma surface activation and supercritical fluid technology to produce, for the first time, a 2-oxazoline-grafted 3D surface with broad-spectrum contact-active antimicrobial properties. Oligo(2-methyl-2-oxazoline) quaternized with N,N-dimethyldodecylamine and grafted to a chitosan (CHT) scaffold (CHT-OMetOx-DDA) efficiently and quickly (<3 min) killed >99.999% of Staphylococcus aureus and Escherichia coli cells upon direct contact and avoided bacterial adhesion to the materials surface, which is important for the prevention of biofilm formation. As a proof of concept, CHT-OMetOx-DDA scaffold was demonstrated to be suitable for water purification efficiently killing the microorganisms present in different water samples within minutes of contact and without leaching to the water. Additionally, we report for the first time a new method to clearly distinguish two mechanisms of action of bioactive surfaces: contact-active and releasing systems.

  6. Zhongshania antarctica gen. nov., sp. nov. and Zhongshania guokunii sp. nov., gammaproteobacteria respectively isolated from coastal attached (fast) ice and surface seawater of the Antarctic.

    PubMed

    Li, Hui-Juan; Zhang, Xi-Ying; Chen, Chun-Xiao; Zhang, Yan-Jiao; Gao, Zhao-Ming; Yu, Yong; Chen, Xiu-Lan; Chen, Bo; Zhang, Yu-Zhong

    2011-09-01

    Two Gram-negative, motile, aerobic, catalase- and oxidase-positive, rod-shaped strains, designated ZS5-23(T) and ZS6-22(T), were respectively isolated from Antarctic coastal attached (fast) ice and surface seawater samples. Both strains could grow at 4-35 °C (optimum 30 °C) and in the absence of NaCl. Analyses of 16S rRNA gene sequences revealed that strains ZS5-23(T) and ZS6-22(T) were closely related to each other (99.0 % sequence similarity) and belonged to the class Gammaproteobacteria, with their closest relatives being Spongiibacter and Melitea species (93.1-94.3 % sequence similarity). The predominant cellular fatty acids in both strains were C₁₇:₁ω8c, C₁₇:₀ and summed feature 3 (C₁₆:₁ω7c and/or iso-C₁₅:₀ 2-OH). Genomic DNA G+C contents of strains ZS5-23(T) and ZS6-22(T) were 51.5 and 51.8 mol%, respectively. The DNA-DNA relatedness between strains ZS5-23(T) and ZS6-22(T) was 50.9 %. Strains ZS5-23(T) and ZS6-22(T) could be differentiated from each other and from Spongiibacter and Melitea species by differences in a number of phenotypic properties. Based on the data presented, strains ZS5-23(T) and ZS6-22(T) represent two novel species in a new genus in the class Gammaproteobacteria, for which the names Zhongshania antarctica gen. nov., sp. nov. (the type species) and Zhongshania guokunii sp. nov. are proposed. The type strain of Zhongshania antarctica is ZS5-23(T) ( = KACC 14066(T)  = CCTCC AB 209246(T)) and that of Zhongshania guokunii is ZS6-22(T) ( = KACC 14532(T)  = CCTCC AB 209247(T)).

  7. Real-time fMRI data analysis using region of interest selection based on fast ICA

    NASA Astrophysics Data System (ADS)

    Xie, Baoquan; Ma, Xinyue; Yao, Li; Long, Zhiying; Zhao, Xiaojie

    2011-03-01

    Real-time functional magnetic resonance imaging (rtfMRI) is a new technique which can present (feedback) brain activity during scanning. Through fast acquisition and online analysis of BOLD signal, fMRI data are processed within one TR. Current rtfMRI provides an activation map under specific task mainly through the GLM analysis to select region of interest (ROI). This study was based on independent component analysis (ICA) and used the result of fast ICA analysis to select the node of the functional network as the ROI. Real-time brain activity within the ROI was presented to the subject who needed to find strategies to control his brain activity. The whole real-time processes involved three parts: pre-processing (including head motion correction and smoothing), fast ICA analysis and feedback. In addition, the result of fast head motion correction was also presented to the experimenter in a curve diagram. Based on the above analysis processes, a real time feedback experiment with a motor imagery task was performed. An overt finger movement task as localizer session was adopted for ICA analysis to get the motor network. Supplementary motor area (SMA) in such network was selected as the ROI. During the feedback session, the average of BOLD signals within ROI was presented to the subjects for self-regulation under a motor imagery task. In this experiment, TR was 1.5 seconds, and the whole time of processing and presentation was within 1 second. Experimental results not only showed that the SMA was controllable, but also proved that the analysis method was effective.

  8. Green ultra-fast high-performance liquid chromatographic method using a short narrow-bore column packed with fully porous sub-2 μm particles for the simultaneous determination of selected pharmaceuticals as surface water and wastewater pollutants.

    PubMed

    Shaaban, Heba; Górecki, Tadeusz

    2013-01-01

    Fast separations are very desirable in laboratories that analyze large numbers of samples per day or those needing short turn-around times. Traditional HPLC methods using conventional stationary phases and standard column dimensions require significant amounts of organic solvents and generate large volumes of waste. With growing awareness about the environment, the development of green technologies has been receiving increasing attention. In this work, a very fast green analytical method based on LC-UV using a short narrow bore column packed with fully porous sub-2 μm particles has been developed for simultaneous determination of nine pharmaceuticals in wastewater and surface water. The chromatographic separation was optimized in order to achieve short analysis time and good resolution for all analytes in a single run. All analytes could be separated in 1 min with good resolution. Sample preparation was executed by solid phase extraction using Oasis HLB cartridges. The method developed was validated based on parameters such as linearity, precision, accuracy, detection, and quantification limits. The recovery ranged from 70.9 to 92.5% with SDs not higher than 5.4%, except for acetaminophen and sulphanilamide. LODs ranged from 0.6-2.5 μg/L, while the LOQs were in the range 2-8 μg/L.

  9. Wavelet-based detection of clods on a soil surface

    NASA Astrophysics Data System (ADS)

    Vannier, E.; Ciarletti, V.; Darboux, F.

    2009-11-01

    One of the aims of the tillage operation is to produce a specific range of clod sizes, suitable for plant emergence. Due to its cloddy structure, a tilled soil surface has its own roughness, which is connected also with soil water content and erosion phenomena. The comprehension and modeling of surface runoff and erosion require that the micro-topography of the soil surface is well estimated. Therefore, the present paper focuses on the soil surface analysis and characterization. An original method consisting in detecting the individual clods or large aggregates on a 3D digital elevation model (DEM) of the soil surface is introduced. A multiresolution decomposition of the surface is performed by wavelet transform. Then a supervised local maxima extraction is performed on the different sub surfaces and a last process makes the validation of the extractions and the merging of the different scales. The method of detection was evaluated with the help of a soil scientist on a controlled surface made in the laboratory as well as on real seedbed and ploughed surfaces, made by tillage operations in an agricultural field. The identifications of the clods are in good agreement, with an overall sensitivity of 84% and a specificity of 94%. The false positive or false negative detections may have several causes. Some very nearby clods may have been smoothed together in the approximation process. Other clods may be embedded into another peace of the surface relief such as another bigger clod or a part of the furrow. At last, the low levels of decomposition are dependent on the resolution and the measurement noise of the DEM. Therefore, some borders of clods may be difficult to determine. The wavelet-based detection method seems to be suitable for soil surfaces described by 2 or 3 levels of approximation such as seedbeds.

  10. Local functional descriptors for surface comparison based binding prediction

    PubMed Central

    2012-01-01

    Background Molecular recognition in proteins occurs due to appropriate arrangements of physical, chemical, and geometric properties of an atomic surface. Similar surface regions should create similar binding interfaces. Effective methods for comparing surface regions can be used in identifying similar regions, and to predict interactions without regard to the underlying structural scaffold that creates the surface. Results We present a new descriptor for protein functional surfaces and algorithms for using these descriptors to compare protein surface regions to identify ligand binding interfaces. Our approach uses descriptors of local regions of the surface, and assembles collections of matches to compare larger regions. Our approach uses a variety of physical, chemical, and geometric properties, adaptively weighting these properties as appropriate for different regions of the interface. Our approach builds a classifier based on a training corpus of examples of binding sites of the target ligand. The constructed classifiers can be applied to a query protein providing a probability for each position on the protein that the position is part of a binding interface. We demonstrate the effectiveness of the approach on a number of benchmarks, demonstrating performance that is comparable to the state-of-the-art, with an approach with more generality than these prior methods. Conclusions Local functional descriptors offer a new method for protein surface comparison that is sufficiently flexible to serve in a variety of applications. PMID:23176080

  11. Integration of remote sensing based surface information into a three-dimensional microclimate model

    NASA Astrophysics Data System (ADS)

    Heldens, Wieke; Heiden, Uta; Esch, Thomas; Mueller, Andreas; Dech, Stefan

    2017-03-01

    Climate change urges cities to consider the urban climate as part of sustainable planning. Urban microclimate models can provide knowledge on the climate at building block level. However, very detailed information on the area of interest is required. Most microclimate studies therefore make use of assumptions and generalizations to describe the model area. Remote sensing data with area wide coverage provides a means to derive many parameters at the detailed spatial and thematic scale required by urban climate models. This study shows how microclimate simulations for a series of real world urban areas can be supported by using remote sensing data. In an automated process, surface materials, albedo, LAI/LAD and object height have been derived and integrated into the urban microclimate model ENVI-met. Multiple microclimate simulations have been carried out both with the dynamic remote sensing based input data as well as with manual and static input data to analyze the impact of the RS-based surface information and the suitability of the applied data and techniques. A valuable support of the integration of the remote sensing based input data for ENVI-met is the use of an automated processing chain. This saves tedious manual editing and allows for fast and area wide generation of simulation areas. The analysis of the different modes shows the importance of high quality height data, detailed surface material information and albedo.

  12. Solvent-free melt electrospinning for preparation of fast dissolving drug delivery system and comparison with solvent-based electrospun and melt extruded systems.

    PubMed

    Nagy, Zsombor Kristóf; Balogh, Attlia; Drávavölgyi, Gábor; Ferguson, James; Pataki, Hajnalka; Vajna, Balázs; Marosi, György

    2013-02-01

    The solvent-free melt electrospinning (MES) method was developed to prepare a drug delivery system with fast release of carvedilol (CAR), a drug with poor water solubility. To the authors knowledge, this is the first report for preparing drug-loaded melt electrospun fibers. Cationic methacrylate copolymer of Eudragit® E type was used as a fiber forming polymer matrix. For comparison, ethanol-based electrospinning and melt extrusion (EX) methods were used to produce samples that had the same composition as the melt electrospun system. According to the results of scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and Fourier transformed infrared spectrometry investigations, amorphous solid nanodispersions/solutions of CAR in Eudragit® E matrix were obtained in all cases with 20 m/m % drug content. In vitro drug release in acidic media from the extrudates was significantly faster (5 min) than that from crystalline CAR. Moreover, ultrafast drug release was achieved from the solvent-free melt and ethanol-based electrospun samples because of their huge surface area and the soluble polymer matrix in the acidic media. These results demonstrate that solvent-free MES is a promising, novel technique for the production of drug delivery systems with enhanced dissolution because it can combine the advantages of EX (e.g., solvent-free, continuous process, and effective amorphization) and solvent-based electrospinning (huge product surface area).

  13. Nanoparticle-Based Surface Modifications for Microtribology Control and Superhydrophobicity

    NASA Astrophysics Data System (ADS)

    Hurst, Kendall Matthew

    2010-11-01

    The emergence of miniaturization techniques for consumer electronics has brought forth the relatively new and exciting field of microelectromechanical systems (MEMS). However, due to the inherent forces that exist between surfaces at the micro- and nanoscale, scientists and semiconductor manufacturers are still struggling to improve the lifetime and reliability of complex microdevices. Due to the extremely large surface area-to-volume ratio of typical MEMS and microstructured surfaces, dominant interfacial forces exist which can be detrimental to their operational lifetime. In particular, van der Waals, capillary, and electrostatic forces contribute to the permanent adhesion, or stiction , of microfabricated surfaces. This strong adhesion force also contributes to the friction and wear of these silicon-based systems. The scope of this work was to examine the effect of utilizing nanoparticles as the basis for roughening surfaces for the purpose of creating films with anti-adhesive and/or superhydrophobic properties. All of the studies presented in this work are focused around a gas-expanded liquid (GXL) process that promotes the deposition of colloidal gold nanoparticles (AuNPs) into conformal thin films. The GXL particle deposition process is finalized by a critical point drying step which is advantageous to the microelectromechanical systems and semiconductor (IC) industries. In fact, preliminary results illustrated that the GXL particle deposition process can easily be integrated into current MEMS microfabrication processes. Thin films of AuNPs deposited onto the surfaces of silicon-based MEMS and tribology test devices were shown to have a dramatic effect on the adhesion of microstructures. In the various investigations, the apparent work of adhesion between surfaces was reduced by 2-4 orders of magnitude. This effect is greatly attributed to the roughening of the typically smooth silicon oxide surfaces which, in turn, dramatically decreases the "real are of

  14. Catalytic Fast Pyrolysis of Lignin over High-Surface-Area Mesoporous Aluminosilicates: Effect of Porosity and Acidity.

    PubMed

    Custodis, Victoria B F; Karakoulia, Stamatia A; Triantafyllidis, Kostas S; van Bokhoven, Jeroen A

    2016-05-23

    Catalytic fast pyrolysis (CFP) of lignin with amorphous mesoporous aluminosilicates catalysts yields a high fraction of aromatics and a relatively low amount of char/coke. The relationship between the acidity and porosity of Al-MCM-41, Al-SBA-15, and Al-MSU-J with product selectivity during lignin CFP is determined. The acid sites (mild Brønsted and stronger Lewis) are able to catalyze pyrolysis intermediates towards fewer oxygenated phenols and aromatic hydrocarbons. A generalized correlation of the product selectivity and yield with the aluminum content and acidity of the mesoporous aluminosilicates is hard to establish. Zeolitic strong acid sites are not required to achieve high conversion and selectivity to aromatic hydrocarbon because nanosized MCM-41 produces a high liquid yield and selectivity. The two most essential parameters are diffusion, which is influenced by pore and grain size, and the active site, which may be mildly acidic, but is dominated by Lewis acid sites. Nanosized grains and mild acidity are essential ingredients for a good lignin CFP catalyst.

  15. Fast O2 Binding at Dicopper Complexes Containing Schiff-Base Dinucleating Ligands

    PubMed Central

    Company, Anna; Gómez, Laura; Mas-Ballesté, Rubén; Korendovych, Ivan V.; Ribas, Xavi; Poater, Albert; Parella, Teodor; Fontrodona, Xavier; Benet-Buchholz, Jordi; Solà, Miquel; Que, Lawrence; Rybak-Akimova, Elena; Costas, Miquel

    2008-01-01

    A new family of dicopper(I) complexes [CuI2RL](X)2, (R = H, 1X, R = tBu, 2X and R = NO2, 3X, X = CF3SO3, ClO4, SbF6 or BArF, BArF = [B{3,5-(CF3)2-C6H3}4]−), where RL is a Schiff-base ligand containing two tridentate binding sites linked by a xylyl spacer have been prepared, characterized, and their reaction with O2 studied. The complexes were designed with the aim of reproducing structural aspects of the active site of type 3 dicopper proteins; they contain two three-coordinate copper sites and a rather flexible podand ligand backbone. The solid state structures of 1ClO4, 2CF3SO3, 2ClO4 and 3BArF·CH3CN have been established by single crystal X-ray diffraction analysis. 1ClO4 adopts a polymeric structure in solution while 2CF3SO3, 2ClO4 and 3BArF·CH3CN are monomeric. The complexes have been studied in solution by means of 1H and 19F NMR spectroscopy, which put forward the presence of dynamic processes in solution. 1-3BArF and 1-3CF3SO3 in acetone react rapidly with O2 to generate metaestable [CuIII2(μ-O)2(RL)]2+ 1-3(O2) and [CuIII2(μ-O)2(CF3SO3)(RL)]+ 1-3(O2)(CF3SO3) species, respectively that have been characterized by UV-vis spectroscopy and resonance Raman analysis. Instead, reaction of 1-3BArF with O2 in CH2Cl2 results in intermolecular O2 binding. DFT methods have been used to study the chemical identities and structural parameters of the O2 adducts, and the relative stability of the CuIII2(μ-O)2 form with respect to the CuII2(μ-η2: η2-peroxo) isomer. The reaction of 1X, X = CF3SO3 and BArF with O2 in acetone has been studied by stopped-flow exhibiting an unexpected very fast reaction rate (k = 3.82(4) × 103 M−1s−1, ΔH‡ = 4.9 ± 0.5 kJ·mol−1, ΔS‡ = −148 ± 5 J·K−1·mol−1), nearly three orders of magnitude faster than in the parent [CuI2(m-XYLMeAN)]2+. Thermal decomposition of 1-3(O2) does not result in aromatic hydroxylation. The mechanism and kinetics of O2 binding to 1X (X = CF3SO3 and BArF) is discussed and compared with those

  16. Fabrication of non-polar GaN based highly responsive and fast UV photodetector

    NASA Astrophysics Data System (ADS)

    Gundimeda, Abhiram; Krishna, Shibin; Aggarwal, Neha; Sharma, Alka; Sharma, Nita Dilawar; Maurya, K. K.; Husale, Sudhir; Gupta, Govind

    2017-03-01

    We report the fabrication of ultraviolet photodetector on non-polar (11-20), nearly stress free, Gallium Nitride (GaN) film epitaxially grown on r-plane (1-102) sapphire substrate. High crystalline film leads to the formation of two faceted triangular islands like structures on the surface. The fabricated GaN ultraviolet photodetector exhibited a high responsivity of 340 mA/W at 5 V bias at room temperature which is the best performance reported for a-GaN/r-sapphire films. A detectivity of 1.24 × 109 Jones and noise equivalent power of 2.4 × 10-11 WHz-1/2 were also attained. The rise time and decay time of 280 ms and 450 ms have been calculated, respectively, which were the fastest response times reported for non-polar GaN ultraviolet photodetector. Such high performance devices substantiate that non-polar GaN can serve as an excellent photoconductive material for ultraviolet photodetector based applications.

  17. A Fast Response Ammonia Sensor Based on Coaxial PPy–PAN Nanofiber Yarn

    PubMed Central

    Liu, Penghong; Wu, Shaohua; Zhang, Yue; Zhang, Hongnan; Qin, Xiaohong

    2016-01-01

    Highly orientated polypyrrole (PPy)–coated polyacrylonitrile (PAN) (PPy–PAN) nanofiber yarn was prepared with an electrospinning technique and in-situ chemical polymerization. The morphology and chemical structure of PPy–PAN nanofiber yarn was characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and fourier transform infrared spectroscopy (FTIR), which indicated that the PPy as the shell layer was homogeneously and uniformly polymerized on the surface of PAN nanofiber. The effects of different concentration of doping acid on the responses of PPy–PAN nanofiber yarn sensor were investigated. The electrical responses of the gas sensor based on the PPy–PAN nanofiber yarn to ammonia were investigated at room temperature. The nanoyarn sensor composed of uniaxially aligned PPy–PAN nanofibers with a one-dimensional structure exhibited a transient response, and the response time was less than 1 s. The excellent sensing properties mentioned above give rise to good potential application prospects in the field of ammonia sensor. PMID:28335248

  18. Development of SiPM-based scintillator tile detectors for a multi-layer fast neutron tracker

    NASA Astrophysics Data System (ADS)

    Preston, R.; Jakubek, J.; Prokopovich, D.; Uher, J.

    2012-10-01

    We are developing thin tile scintillator detectors with silicon photomultiplier (SiPM) readout for use in a multi-layer fast-neutron tracker. The tracker is based on interleaved Timepix and plastic scintillator layers. The thin 15 × 15 × 2 mm plastic scintillators require suitable optical readout in order to detect and measure the energy lost by energetic protons that have been recoiled by fast neutrons. Our first prototype used dual SiPMs, coupled to opposite edges of the scintillator tile using light-guides. An alternative readout geometry was designed in an effort to increase the fraction of scintillation light detected by the SiPMs. The new prototype uses a larger SiPM array to cover the entire top face of the tile. This paper details the comparative performance of the two prototype designs. A deuterium-tritium (DT) fast-neutron source was used to compare the relative light collection efficiency of the two designs. A collimated UV light source was scanned across the detector face to map the uniformity. The new prototype was found to have 9.5 times better light collection efficiency over the original design. Both prototypes exhibit spatial non-uniformity in their response. Methods of correcting this non-uniformity are discussed.

  19. Fast freeze-drying cycle design and optimization using a PAT based on the measurement of product temperature.

    PubMed

    Bosca, Serena; Barresi, Antonello A; Fissore, Davide

    2013-10-01

    This paper is focused on the use of an innovative Process Analytical Technology for the fast design and optimization of freeze-drying cycles for pharmaceuticals. The tool is based on a soft-sensor, a device that uses the experimental measure of product temperature during freeze-drying, a mathematical model of the process, and the Extended Kalman Filter algorithm to estimate the sublimation flux, the residual amount of ice in the vial, and some model parameters (heat and mass transfer coefficients). The accuracy of the estimations provided by the soft-sensor has been shown using as test case aqueous solutions containing different excipients (sucrose, polyvinylpyrrolidone), processed at various operating conditions, pointing out that the soft-sensor allows a fast estimation of model parameters and product dynamics without involving expensive hardware or time consuming analysis. The possibility of using the soft-sensor to calculate in-line (or off-line) the design space of the primary drying phase is here presented and discussed. Results evidences that by this way, it is possible to identify the values of the heating fluid temperature that maintain product temperature below the limit value, as well as the operating conditions that maximize the sublimation flux. Various experiments have been carried out to test the effectiveness of the proposed approach for a fast design of the cycle, evidencing that drying time can be significantly reduced, without impairing product quality.

  20. SU-F-BRD-07: Fast Monte Carlo-Based Biological Optimization of Proton Therapy Treatment Plans for Thyroid Tumors

    SciTech Connect

    Wan Chan Tseung, H; Ma, J; Ma, D; Beltran, C

    2015-06-15

    Purpose: To demonstrate the feasibility of fast Monte Carlo (MC) based biological planning for the treatment of thyroid tumors in spot-scanning proton therapy. Methods: Recently, we developed a fast and accurate GPU-based MC simulation of proton transport that was benchmarked against Geant4.9.6 and used as the dose calculation engine in a clinically-applicable GPU-accelerated IMPT optimizer. Besides dose, it can simultaneously score the dose-averaged LET (LETd), which makes fast biological dose (BD) estimates possible. To convert from LETd to BD, we used a linear relation based on cellular irradiation data. Given a thyroid patient with a 93cc tumor volume, we created a 2-field IMPT plan in Eclipse (Varian Medical Systems). This plan was re-calculated with our MC to obtain the BD distribution. A second 5-field plan was made with our in-house optimizer, using pre-generated MC dose and LETd maps. Constraints were placed to maintain the target dose to within 25% of the prescription, while maximizing the BD. The plan optimization and calculation of dose and LETd maps were performed on a GPU cluster. The conventional IMPT and biologically-optimized plans were compared. Results: The mean target physical and biological doses from our biologically-optimized plan were, respectively, 5% and 14% higher than those from the MC re-calculation of the IMPT plan. Dose sparing to critical structures in our plan was also improved. The biological optimization, including the initial dose and LETd map calculations, can be completed in a clinically viable time (∼30 minutes) on a cluster of 25 GPUs. Conclusion: Taking advantage of GPU acceleration, we created a MC-based, biologically optimized treatment plan for a thyroid patient. Compared to a standard IMPT plan, a 5% increase in the target’s physical dose resulted in ∼3 times as much increase in the BD. Biological planning was thus effective in escalating the target BD.

  1. Radar cross-section reduction based on an iterative fast Fourier transform optimized metasurface

    NASA Astrophysics Data System (ADS)

    Song, Yi-Chuan; Ding, Jun; Guo, Chen-Jiang; Ren, Yu-Hui; Zhang, Jia-Kai

    2016-07-01

    A novel polarization insensitive metasurface with over 25 dB monostatic radar cross-section (RCS) reduction is introduced. The proposed metasurface is comprised of carefully arranged unit cells with spatially varied dimension, which enables approximate uniform diffusion of incoming electromagnetic (EM) energy and reduces the threat from bistatic radar system. An iterative fast Fourier transform (FFT) method for conventional antenna array pattern synthesis is innovatively applied to find the best unit cell geometry parameter arrangement. Finally, a metasurface sample is fabricated and tested to validate RCS reduction behavior predicted by full wave simulation software Ansys HFSSTM and marvelous agreement is observed.

  2. WE-D-9A-01: A Novel Mesh-Based Deformable Surface-Contour Registration

    SciTech Connect

    Zhong, Z; Cai, Y; Guo, X; Jia, X; Chiu, T; Kearney, V; Liu, H; Jiang, L; Chen, S; Yordy, J; Nedzi, L; Mao, W

    2014-06-15

    Purpose: Initial guess is vital for 3D-2D deformable image registration (DIR) while dealing with large deformations for adaptive radiation therapy. A fast procedure has been developed to deform body surface to match 2D body contour on projections. This surface-contour DIR will provide an initial deformation for further complete 3D DIR or image reconstruction. Methods: Both planning CT images and come-beam CT (CBCT) projections are preprocessed to create 0–1 binary mask. Then the body surface and CBCT projection body contours are extracted by Canny edge detector. A finite element modeling system was developed to automatically generate adaptive meshes based on the image surface. After that, the projections of the CT surface voxels are computed and compared with corresponding 2D projection contours from CBCT scans. As a result, the displacement vector field (DVF) on mesh vertices around the surface was optimized iteratively until the shortest Euclidean distance between the pixels on the projections of the deformed CT surface and the corresponding CBCT projection contour is minimized. With the help of the tetrahedral meshes, we can smoothly diffuse the deformation from the surface into the interior of the volume. Finally, the deformed CT images are obtained by the optimal DVF applied on the original planning CT images. Results: The accuracy of the surface-contour registration is evaluated by 3D normalized cross correlation increased from 0.9176 to 0.9957 (sphere-ellipsoid phantom) and from 0.7627 to 0.7919 (H and N cancer patient data). Under the GPU-based implementation, our surface-contour-guided method on H and N cancer patient data takes 8 seconds/iteration, about 7.5 times faster than direct 3D method (60 seconds/iteration), and it needs fewer optimization iterations (30 iterations vs 50 iterations). Conclusion: The proposed surface-contour DIR method can substantially improve both the accuracy and the speed of reconstructing volumetric images, which is helpful

  3. Fast catheter segmentation from echocardiographic sequences based on segmentation from corresponding X-ray fluoroscopy for cardiac catheterization interventions.

    PubMed

    Wu, Xianliang; Housden, James; Ma, YingLiang; Razavi, Benjamin; Rhode, Kawal; Rueckert, Daniel

    2015-04-01

    Echocardiography is a potential alternative to X-ray fluoroscopy in cardiac catheterization given its richness in soft tissue information and its lack of ionizing radiation. However, its small field of view and acoustic artifacts make direct automatic segmentation of the catheters very challenging. In this study, a fast catheter segmentation framework for echocardiographic imaging guided by the segmentation of corresponding X-ray fluoroscopic imaging is proposed. The complete framework consists of: 1) catheter initialization in the first X-ray frame; 2) catheter tracking in the rest of the X-ray sequence; 3) fast registration of corresponding X-ray and ultrasound frames; and 4) catheter segmentation in ultrasound images guided by the results of both X-ray tracking and fast registration. The main contributions include: 1) a Kalman filter-based growing strategy with more clinical data evalution; 2) a SURF detector applied in a constrained search space for catheter segmentation in ultrasound images; 3) a two layer hierarchical graph model to integrate and smooth catheter fragments into a complete catheter; and 4) the integration of these components into a system for clinical applications. This framework is evaluated on five sequences of porcine data and four sequences of patient data comprising more than 3000 X-ray frames and more than 1000 ultrasound frames. The results show that our algorithm is able to track the catheter in ultrasound images at 1.3 s per frame, with an error of less than 2 mm. However, although this may satisfy the accuracy for visualization purposes and is also fast, the algorithm still needs to be further accelerated for real-time clinical applications.

  4. Surface geometry based hydrophobicity of the PDMS for microfluidic devices

    NASA Astrophysics Data System (ADS)

    Pelayo, J. C.; Badiola, R. A.; Castañares, J.; Pili, U.; Violanda, R.; Bacabac, R.

    2015-06-01

    In this report, the surface hydrophobicity of PDMS was investigated using two methods of preparations. The first method was performed by changing the surface roughness through the use of different molds. The second method was performed by varying the reconstitution ratio (volume of elastomer base to volume of elastomer curing) of the PDMS. Variation in the hydrophobicity of the PDMS was characterized by measuring the contact angle of a liquid droplet against the surface of the PDMS. The results showed that both the surface roughness and the reconstitution ratio of the PDMS positively correlated with the contact angle measured regardless of the liquid used. The maximum and minimum contact angle obtained were θr = (138 ± 3)° and θr = (99 ± 3)°, respectively. The results demonstrate a straightforward way of fabricating microfluidic devices using PDMS with controlled hydrophobicity.

  5. Fast pseudo-CT synthesis from MRI T1-weighted images using a patch-based approach

    NASA Astrophysics Data System (ADS)

    Torrado-Carvajal, A.; Alcain, E.; Montemayor, A. S.; Herraiz, J. L.; Rozenholc, Y.; Hernandez-Tamames, J. A.; Adalsteinsson, E.; Wald, L. L.; Malpica, N.

    2015-12-01

    MRI-based bone segmentation is a challenging task because bone tissue and air both present low signal intensity on MR images, making it difficult to accurately delimit the bone boundaries. However, estimating bone from MRI images may allow decreasing patient ionization by removing the need of patient-specific CT acquisition in several applications. In this work, we propose a fast GPU-based pseudo-CT generation from a patient-specific MRI T1-weighted image using a group-wise patch-based approach and a limited MRI and CT atlas dictionary. For every voxel in the input MR image, we compute the similarity of the patch containing that voxel with the patches of all MR images in the database, which lie in a certain anatomical neighborhood. The pseudo-CT is obtained as a local weighted linear combination of the CT values of the corresponding patches. The algorithm was implemented in a GPU. The use of patch-based techniques allows a fast and accurate estimation of the pseudo-CT from MR T1-weighted images, with a similar accuracy as the patient-specific CT. The experimental normalized cross correlation reaches 0.9324±0.0048 for an atlas with 10 datasets. The high NCC values indicate how our method can accurately approximate the patient-specific CT. The GPU implementation led to a substantial decrease in computational time making the approach suitable for real applications.

  6. Fully iterative scatter corrected digital breast tomosynthesis using GPU-based fast Monte Carlo simulation and composition ratio update

    SciTech Connect

    Kim, Kyungsang; Ye, Jong Chul; Lee, Taewon; Cho, Seungryong; Seong, Younghun; Lee, Jongha; Jang, Kwang Eun; Choi, Jaegu; Choi, Young Wook; Kim, Hak Hee; Shin, Hee Jung; Cha, Joo Hee

    2015-09-15

    Purpose: In digital breast tomosynthesis (DBT), scatter correction is highly desirable, as it improves image quality at low doses. Because the DBT detector panel is typically stationary during the source rotation, antiscatter grids are not generally compatible with DBT; thus, a software-based scatter correction is required. This work proposes a fully iterative scatter correction method that uses a novel fast Monte Carlo simulation (MCS) with a tissue-composition ratio estimation technique for DBT imaging. Methods: To apply MCS to scatter estimation, the material composition in each voxel should be known. To overcome the lack of prior accurate knowledge of tissue composition for DBT, a tissue-composition ratio is estimated based on the observation that the breast tissues are principally composed of adipose and glandular tissues. Using this approximation, the composition ratio can be estimated from the reconstructed attenuation coefficients, and the scatter distribution can then be estimated by MCS using the composition ratio. The scatter estimation and image reconstruction procedures can be performed iteratively until an acceptable accuracy is achieved. For practical use, (i) the authors have implemented a fast MCS using a graphics processing unit (GPU), (ii) the MCS is simplified to transport only x-rays in the energy range of 10–50 keV, modeling Rayleigh and Compton scattering and the photoelectric effect using the tissue-composition ratio of adipose and glandular tissues, and (iii) downsampling is used because the scatter distribution varies rather smoothly. Results: The authors have demonstrated that the proposed method can accurately estimate the scatter distribution, and that the contrast-to-noise ratio of the final reconstructed image is significantly improved. The authors validated the performance of the MCS by changing the tissue thickness, composition ratio, and x-ray energy. The authors confirmed that the tissue-composition ratio estimation was quite

  7. Development of a PYTHON-based emittance calculator at Fermilab Accelerator Science and Technology (FAST) facility

    NASA Astrophysics Data System (ADS)

    Green, A. T.

    Beam emittance is an important characteristic describing charged particle beams. In linear accelerators (linac), it is critical to characterize the beam phase space parameters and, in particular, to precisely measure transverse beam emittance. The quadrupole scan (quad-scan) is a well-established technique used to characterize transverse beam parameters in four-dimensional phase space, including beam emittance. A computational algorithm with PYTHON scripts has been developed to estimate beam parameters, in particular beam emittance, using the quad-scan technique in the electron linac at the Fermilab Accelerator Science and Technology (FAST) facility. This script has been implemented in conjunction with an automated quad-scan tool (also written in PYTHON) and has decreased the time it takes to perform a single quad-scan from an hour to a few minutes. From the experimental data, the emittance calculator quickly delivers several results including: geometrical and normalized transverse emittance, Courant-Snyder parameters, and plots of the beam size versus quadrupole field strength, among others. This paper will discuss the details of the techniques used, the results from several quad-scans preformed at FAST during the electron injector commissioning, and the PYTHON code used to obtain the results.

  8. Fast and accurate auto focusing algorithm based on two defocused images using discrete cosine transform

    NASA Astrophysics Data System (ADS)

    Park, Byung-Kwan; Kim, Sung-Su; Chung, Dae-Su; Lee, Seong-Deok; Kim, Chang-Yeong

    2008-02-01

    This paper describes the new method for fast auto focusing in image capturing devices. This is achieved by using two defocused images. At two prefixed lens positions, two defocused images are taken and defocused blur levels in each image are estimated using Discrete Cosine Transform (DCT). These DCT values can be classified into distance from the image capturing device to main object, so we can make distance vs. defocused blur level classifier. With this classifier, relation between two defocused blur levels can give the device the best focused lens step. In the case of ordinary auto focusing like Depth from Focus (DFF), it needs several defocused images and compares high frequency components in each image. Also known as hill-climbing method, the process requires about half number of images in all focus lens steps for focusing in general. Since this new method requires only two defocused images, it can save lots of time for focusing or reduce shutter lag time. Compared to existing Depth from Defocus (DFD) which uses two defocused images, this new algorithm is simple and accurate as DFF method. Because of this simplicity and accuracy, this method can also be applied to fast 3D depth map construction.

  9. Effect of land cover and green space on land surface temperature of a fast growing economic region in Malaysia

    NASA Astrophysics Data System (ADS)

    Sheikhi, A.; Kanniah, K. D.; Ho, C. H.

    2015-10-01

    Green space must be increased in the development of new cities as green space can moderate temperature in the cities. In this study we estimated the land surface temperature (LST) and established relationships between LST and land cover and various vegetation and urban surface indices in the Iskandar Malaysia (IM) region. IM is one of the emerging economic gateways of Malaysia, and is envisaged to transform into a metropolis by 2025. This change may cause increased temperature in IM and therefore we conducted a study by using Landsat 5 image covering the study region (2,217 km2) to estimate LST, classify different land covers and calculate spectral indices. Results show that urban surface had highest LST (24.49 °C) and the lowest temperature was recorded in, forest, rubber and water bodies ( 20.69 to 21.02°C). Oil palm plantations showed intermediate mean LST values with 21.65 °C. We further investigated the relationship between vegetation and build up densities with temperature. We extracted 1000 collocated pure pixels of Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Normalized Difference Built-up Index (NDBI), Urban Index (UI) and LST in the study area. Results show a strong and significant negative correlation with (R2= -0.74 and -0.79) respectively between NDVI, NDWI and LST . Meanwhile a strong positive correlation (R2=0.8 and 0.86) exists between NDBI, UI and LST. These results show the importance of increasing green cover in urban environment to combat any adverse effects of climate change.

  10. Fiber optic surface plasmon resonance based ethanol sensor

    NASA Astrophysics Data System (ADS)

    Verma, Roli; Gupta, Banshi D.

    2014-03-01

    A design of SPR based fiber optic ethanol biosensor is presented by using enzyme alcohol dehydrogenase and nicotinic acid. The sensing probe is fabricated with the coating of 40 nm thin film of silver metal and immobilization of alcohol dehydrogenase and nicotinic acid by gel entrapment method over unclad core of a multimode optical fiber. The SPR spectra of ethanol samples of concentrations ranging from 0 mM to 10 mM prepared in buffer have been recorded. The sensor works on the spectral interrogation technique and operates in the visible range of the spectrum. The SPR curves are blue shifted with the increasing concentration of ethanol and the sensitivity of the sensor decreases with the increasing concentration of ethanol. The sensor has many advantages such as fast response, stability, small probe size, low cost and can be u