Frequency domain phase retrieval of simultaneous multi-wavelength phase-shifting interferometry

International Nuclear Information System (INIS)

Yin, Zhenxing; Zhong, Liyun; Xu, Xiaofei; Zhang, Wangping; Lu, Xiaoxu; Tian, Jindong

2016-01-01

In simultaneous multi-wavelength phase-shifting interferometry, we propose a novel frequency domain phase retrieval (FDPR) algorithm. First, using only a one-time phase-shifting operation, a sequence of simultaneous multi-wavelength phase-shifting interferograms (SPSMWIs) are captured by a monochrome charge-coupled device. Second, by performing a Fourier transform for each pixel of SPSMWIs, the wrapped phases of each wavelength can be retrieved from the complex amplitude located in the spectral peak of each wavelength. Finally, the phase of the synthetic wavelength can be obtained by the subtraction between the wrapped phases of a single wavelength. In this study, the principle and the application condition of the proposed approach are discussed. Both the simulation and the experimental result demonstrate the simple and convenient performance of the proposed FDPR approach. (paper)

Alternating direction methods for classical and ptychographic phase retrieval

International Nuclear Information System (INIS)

Wen, Zaiwen; Yang, Chao; Liu, Xin; Marchesini, Stefano

2012-01-01

In this paper, we show how the augmented Lagrangian alternating direction method (ADM) can be used to solve both the classical and ptychographic phase retrieval problems. We point out the connection between ADM and projection algorithms such as the hybrid input–output algorithm, and compare its performance against standard algorithms for phase retrieval on a number of test images. Our computational experiments show that ADM appears to be less sensitive to the choice of relaxation parameters, and it usually outperforms the existing techniques for both the classical and ptychographic phase retrieval problems. (paper)

Propagation based phase retrieval of simulated intensity measurements using artificial neural networks

Science.gov (United States)

Kemp, Z. D. C.

2018-04-01

Determining the phase of a wave from intensity measurements has many applications in fields such as electron microscopy, visible light optics, and medical imaging. Propagation based phase retrieval, where the phase is obtained from defocused images, has shown significant promise. There are, however, limitations in the accuracy of the retrieved phase arising from such methods. Sources of error include shot noise, image misalignment, and diffraction artifacts. We explore the use of artificial neural networks (ANNs) to improve the accuracy of propagation based phase retrieval algorithms applied to simulated intensity measurements. We employ a phase retrieval algorithm based on the transport-of-intensity equation to obtain the phase from simulated micrographs of procedurally generated specimens. We then train an ANN with pairs of retrieved and exact phases, and use the trained ANN to process a test set of retrieved phase maps. The total error in the phase is significantly reduced using this method. We also discuss a variety of potential extensions to this work.

Blind phase retrieval for aberrated linear shift-invariant imaging systems

International Nuclear Information System (INIS)

Yu, Rotha P; Paganin, David M

2010-01-01

We develop a means to reconstruct an input complex coherent scalar wavefield, given a through focal series (TFS) of three intensity images output from a two-dimensional (2D) linear shift-invariant optical imaging system with unknown aberrations. This blind phase retrieval technique unites two methods, namely (i) TFS phase retrieval and (ii) iterative blind deconvolution. The efficacy of our blind phase retrieval procedure has been demonstrated using simulated data, for a variety of Poisson noise levels.

Generalized phase retrieval algorithm based on information measures

OpenAIRE

Shioya, Hiroyuki; Gohara, Kazutoshi

2006-01-01

An iterative phase retrieval algorithm based on the maximum entropy method (MEM) is presented. Introducing a new generalized information measure, we derive a novel class of algorithms which includes the conventionally used error reduction algorithm and a MEM-type iterative algorithm which is presented for the first time. These different phase retrieval methods are unified on the basis of the framework of information measures used in information theory.

Phase object retrieval through scattering medium

Science.gov (United States)

Zhao, Ming; Zhao, Meijing; Wu, Houde; Xu, Wenhai

2018-05-01

Optical imaging through a scattering medium has been an interesting and important research topic, especially in the field of biomedical imaging. However, it is still a challenging task due to strong scattering. This paper proposes to recover the phase object behind the scattering medium from one single-shot speckle intensity image using calibrated transmission matrices (TMs). We construct the forward model as a non-linear mapping, since the intensity image loses the phase information, and then a generalized phase retrieval algorithm is employed to recover the hidden object. Moreover, we show that a phase object can be reconstructed with a small portion of the speckle image captured by the camera. The simulation is performed to demonstrate our scheme and test its performance. Finally, a real experiment is set up, we measure the TMs from the scattering medium, and then use it to reconstruct the hidden object. We show that a phase object of size 32 × 32 is retrieved from 150 × 150 speckle grains, which is only 1/50 of the speckles area. We believe our proposed method can benefit the community of imaging through the scattering medium.

Complex amplitude reconstruction by iterative amplitude-phase retrieval algorithm with reference

Science.gov (United States)

Shen, Cheng; Guo, Cheng; Tan, Jiubin; Liu, Shutian; Liu, Zhengjun

2018-06-01

Multi-image iterative phase retrieval methods have been successfully applied in plenty of research fields due to their simple but efficient implementation. However, there is a mismatch between the measurement of the first long imaging distance and the sequential interval. In this paper, an amplitude-phase retrieval algorithm with reference is put forward without additional measurements or priori knowledge. It gets rid of measuring the first imaging distance. With a designed update formula, it significantly raises the convergence speed and the reconstruction fidelity, especially in phase retrieval. Its superiority over the original amplitude-phase retrieval (APR) method is validated by numerical analysis and experiments. Furthermore, it provides a conceptual design of a compact holographic image sensor, which can achieve numerical refocusing easily.

Phase retrieval from local measurements in two dimensions

Science.gov (United States)

Iwen, Mark; Preskitt, Brian; Saab, Rayan; Viswanathan, Aditya

2017-08-01

The phase retrieval problem has appeared in a multitude of applications for decades. While ad hoc solutions have existed since the early 1970s, recent developments have provided algorithms that offer promising theoretical guarantees under increasingly realistic assumptions. Motivated by ptychographic imaging, we generalize a recent result on phase retrieval of a one dimensional objective vector x ∈ ℂd to recover a two dimensional sample Q ∈ ℂd x d from phaseless measurements, using a tensor product formulation to extend the previous work.

Measurement range of phase retrieval in optical surface and wavefront metrology

International Nuclear Information System (INIS)

Brady, Gregory R.; Fienup, James R.

2009-01-01

Phase retrieval employs very simple data collection hardware and iterative algorithms to determine the phase of an optical field. We have derived limitations on phase retrieval, as applied to optical surface and wavefront metrology, in terms of the speed of beam (i.e., f-number or numerical aperture) and amount of aberration using arguments based on sampling theory and geometrical optics. These limitations suggest methodologies for expanding these ranges by increasing the complexity of the measurement arrangement, the phase-retrieval algorithm, or both. We have simulated one of these methods where a surface is measured at unusual conjugates

Quantification of signal detection performance degradation induced by phase-retrieval in propagation-based x-ray phase-contrast imaging

Science.gov (United States)

Chou, Cheng-Ying; Anastasio, Mark A.

2016-04-01

In propagation-based X-ray phase-contrast (PB XPC) imaging, the measured image contains a mixture of absorption- and phase-contrast. To obtain separate images of the projected absorption and phase (i.e., refractive) properties of a sample, phase retrieval methods can be employed. It has been suggested that phase-retrieval can always improve image quality in PB XPC imaging. However, when objective (task-based) measures of image quality are employed, this is not necessarily true and phase retrieval can be detrimental. In this work, signal detection theory is utilized to quantify the performance of a Hotelling observer (HO) for detecting a known signal in a known background. Two cases are considered. In the first case, the HO acts directly on the measured intensity data. In the second case, the HO acts on either the retrieved phase or absorption image. We demonstrate that the performance of the HO is superior when acting on the measured intensity data. The loss of task-specific information induced by phase-retrieval is quantified by computing the efficiency of the HO as the ratio of the test statistic signal-to-noise ratio (SNR) for the two cases. The effect of the system geometry on this efficiency is systematically investigated. Our findings confirm that phase-retrieval can impair signal detection performance in XPC imaging.

Transuranic (TRU) Waste Phase I Retrieval Plan

CERN Document Server

McDonald, K M

2000-01-01

From 1970 to 1987, TRU and suspect TRU wastes at Hanford were placed in the SWBG. At the time of placement in the SWBG these wastes were not regulated under existing Resource Conservation and Recovery Act (RCRA) regulations, since they were generated and disposed of prior to the effective date of RCRA at the Hanford Site (1987). From the standpoint of DOE Order 5820.2A1, the TRU wastes are considered retrievably stored, and current plans are to retrieve these wastes for shipment to WIPP for disposal. This plan provides a strategy for the Phase I retrieval that meets the intent of TPA milestone M-91 and Project W-113, and incorporates the lessons learned during TRU retrieval campaigns at Hanford, LANL, and SRS. As in the original Project W-113 plans, the current plan calls for examination of approximately 10,000 suspect-TRU drums located in the 218-W-4C burial ground followed by the retrieval of those drums verified to contain TRU waste. Unlike the older plan, however, this plan proposes an open-air retrieval ...

Spline based iterative phase retrieval algorithm for X-ray differential phase contrast radiography.

Science.gov (United States)

Nilchian, Masih; Wang, Zhentian; Thuering, Thomas; Unser, Michael; Stampanoni, Marco

2015-04-20

Differential phase contrast imaging using grating interferometer is a promising alternative to conventional X-ray radiographic methods. It provides the absorption, differential phase and scattering information of the underlying sample simultaneously. Phase retrieval from the differential phase signal is an essential problem for quantitative analysis in medical imaging. In this paper, we formalize the phase retrieval as a regularized inverse problem, and propose a novel discretization scheme for the derivative operator based on B-spline calculus. The inverse problem is then solved by a constrained regularized weighted-norm algorithm (CRWN) which adopts the properties of B-spline and ensures a fast implementation. The method is evaluated with a tomographic dataset and differential phase contrast mammography data. We demonstrate that the proposed method is able to produce phase image with enhanced and higher soft tissue contrast compared to conventional absorption-based approach, which can potentially provide useful information to mammographic investigations.

X-ray differential phase-contrast tomographic reconstruction with a phase line integral retrieval filter

International Nuclear Information System (INIS)

Fu, Jian; Hu, Xinhua; Li, Chen

2015-01-01

We report an alternative reconstruction technique for x-ray differential phase-contrast computed tomography (DPC-CT). This approach is based on a new phase line integral projection retrieval filter, which is rooted in the derivative property of the Fourier transform and counteracts the differential nature of the DPC-CT projections. It first retrieves the phase line integral from the DPC-CT projections. Then the standard filtered back-projection (FBP) algorithms popular in x-ray absorption-contrast CT are directly applied to the retrieved phase line integrals to reconstruct the DPC-CT images. Compared with the conventional DPC-CT reconstruction algorithms, the proposed method removes the Hilbert imaginary filter and allows for the direct use of absorption-contrast FBP algorithms. Consequently, FBP-oriented image processing techniques and reconstruction acceleration softwares that have already been successfully used in absorption-contrast CT can be directly adopted to improve the DPC-CT image quality and speed up the reconstruction

Rapid compression induced solidification of two amorphous phases of poly(ethylene terephthalate)

Energy Technology Data Exchange (ETDEWEB)

Hong, S M [Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, 610031 (China); Liu, X R [Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, 610031 (China); Su, L [Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, 610031 (China); Huang, D H [Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu, 610031 (China); Li, L B [Foods Research Centre Unilever R and D, Vlaardingen Olivier van Noortlaan, 120, 3133 AT Vlaardingen (Netherlands)

2006-08-21

Melts of poly(ethylene terephthalate) were solidified by rapid compression to 2 GPa within 20 ms and by a series of comparative processes including natural cooling, slow compressing and rapid cooling, respectively. By combining XRD and differential scanning calorimetry data of the recovered samples, it is made clear that rapid compression induces two kinds of amorphous phases. One is relatively stable and can also be formed in the slow compression and the cooling processes. Another is metastable and transforms to crystalline phase at 371 K. This metastable amorphous phase cannot be obtained by slow compression or natural cooling, and its crystallization temperature is remarkably different from that of the metastable amorphous phase formed in the rapid cooling sample.

RETRIEVAL OF AEROSOL PHASE FUNCTION AND POLARIZED PHASE FUNCTION FROM POLARIZATION OF SKYLIGHT FOR DIFFERENT OBSERVATION GEOMETRIES

Directory of Open Access Journals (Sweden)

L. Li

2018-04-01

Full Text Available The phase function and polarized phase function are important optical parameters, which describe scattering properties of atmospheric aerosol particles. Polarization of skylight induced by the scattering processes is sensitive to the scattering properties of aerosols. The Stokes parameters I, Q, U and the polarized radiance Lp of skylight measured by the CIMEL dual-polar sun-sky radiometer CE318- DP can be use to retrieve the phase function and polarized phase function, respectively. Two different observation geometries (i.e., the principal plane and almucantar are preformed by the CE318-DP to detect skylight polarization. Polarization of skylight depends on the illumination and observation geometries. For the same solar zenith angle, retrievals of the phase function and the polarized phase function are still affected by the observation geometry. The performance of the retrieval algorithm for the principal plane and almucantar observation geometries was assessed by the numerical experiments at two typical high and low sun’s positions (i.e. solar zenith angles are equal to 45° and 65°. Comparing the results for the principal plane and almucantar geometries, it is recommended to utilize the principal plane observations to retrieve the phase function when the solar zenith angle is small. The Stokes parameter U and the polarized radiance Lp from the almucantar observations are suggested to retrieve the polarized phase function, especially for short wavelength channels (e.g., 440 and 500 nm.

Retrieval of Aerosol Phase Function and Polarized Phase Function from Polarization of Skylight for Different Observation Geometries

Science.gov (United States)

Li, L.; Qie, L. L.; Xu, H.; Li, Z. Q.

2018-04-01

The phase function and polarized phase function are important optical parameters, which describe scattering properties of atmospheric aerosol particles. Polarization of skylight induced by the scattering processes is sensitive to the scattering properties of aerosols. The Stokes parameters I, Q, U and the polarized radiance Lp of skylight measured by the CIMEL dual-polar sun-sky radiometer CE318- DP can be use to retrieve the phase function and polarized phase function, respectively. Two different observation geometries (i.e., the principal plane and almucantar) are preformed by the CE318-DP to detect skylight polarization. Polarization of skylight depends on the illumination and observation geometries. For the same solar zenith angle, retrievals of the phase function and the polarized phase function are still affected by the observation geometry. The performance of the retrieval algorithm for the principal plane and almucantar observation geometries was assessed by the numerical experiments at two typical high and low sun's positions (i.e. solar zenith angles are equal to 45° and 65°). Comparing the results for the principal plane and almucantar geometries, it is recommended to utilize the principal plane observations to retrieve the phase function when the solar zenith angle is small. The Stokes parameter U and the polarized radiance Lp from the almucantar observations are suggested to retrieve the polarized phase function, especially for short wavelength channels (e.g., 440 and 500 nm).

Three-dimensional propagation in near-field tomographic X-ray phase retrieval

International Nuclear Information System (INIS)

Ruhlandt, Aike; Salditt, Tim

2016-01-01

An extension of phase retrieval algorithms for near-field X-ray (propagation) imaging to three dimensions is presented, enhancing the quality of the reconstruction by exploiting previously unused three-dimensional consistency constraints. This paper presents an extension of phase retrieval algorithms for near-field X-ray (propagation) imaging to three dimensions, enhancing the quality of the reconstruction by exploiting previously unused three-dimensional consistency constraints. The approach is based on a novel three-dimensional propagator and is derived for the case of optically weak objects. It can be easily implemented in current phase retrieval architectures, is computationally efficient and reduces the need for restrictive prior assumptions, resulting in superior reconstruction quality

Feasibility study of the iterative x-ray phase retrieval algorithm

International Nuclear Information System (INIS)

Meng Fanbo; Liu Hong; Wu Xizeng

2009-01-01

An iterative phase retrieval algorithm was previously investigated for in-line x-ray phase imaging. Through detailed theoretical analysis and computer simulations, we now discuss the limitations, robustness, and efficiency of the algorithm. The iterative algorithm was proved robust against imaging noise but sensitive to the variations of several system parameters. It is also efficient in terms of calculation time. It was shown that the algorithm can be applied to phase retrieval based on one phase-contrast image and one attenuation image, or two phase-contrast images; in both cases, the two images can be obtained either by one detector in two exposures, or by two detectors in only one exposure as in the dual-detector scheme

Phase modulated high density collinear holographic data storage system with phase-retrieval reference beam locking and orthogonal reference encoding.

Science.gov (United States)

Liu, Jinpeng; Horimai, Hideyoshi; Lin, Xiao; Huang, Yong; Tan, Xiaodi

2018-02-19

A novel phase modulation method for holographic data storage with phase-retrieval reference beam locking is proposed and incorporated into an amplitude-encoding collinear holographic storage system. Unlike the conventional phase retrieval method, the proposed method locks the data page and the corresponding phase-retrieval interference beam together at the same location with a sequential recording process, which eliminates piezoelectric elements, phase shift arrays and extra interference beams, making the system more compact and phase retrieval easier. To evaluate our proposed phase modulation method, we recorded and then recovered data pages with multilevel phase modulation using two spatial light modulators experimentally. For 4-level, 8-level, and 16-level phase modulation, we achieved the bit error rate (BER) of 0.3%, 1.5% and 6.6% respectively. To further improve data storage density, an orthogonal reference encoding multiplexing method at the same position of medium is also proposed and validated experimentally. We increased the code rate of pure 3/16 amplitude encoding method from 0.5 up to 1.0 and 1.5 using 4-level and 8-level phase modulation respectively.

An improved ptychographical phase retrieval algorithm for diffractive imaging

International Nuclear Information System (INIS)

Maiden, Andrew M.; Rodenburg, John M.

2009-01-01

The ptychographical iterative engine (or PIE) is a recently developed phase retrieval algorithm that employs a series of diffraction patterns recorded as a known illumination function is translated to a set of overlapping positions relative to a target sample. The technique has been demonstrated successfully at optical and X-ray wavelengths and has been shown to be robust to detector noise and to converge considerably faster than support-based phase retrieval methods. In this paper, the PIE is extended so that the requirement for an accurate model of the illumination function is removed.

Genetic Algorithm Phase Retrieval for the Systematic Image-Based Optical Alignment Testbed

Science.gov (United States)

Taylor, Jaime; Rakoczy, John; Steincamp, James

2003-01-01

Phase retrieval requires calculation of the real-valued phase of the pupil fimction from the image intensity distribution and characteristics of an optical system. Genetic 'algorithms were used to solve two one-dimensional phase retrieval problem. A GA successfully estimated the coefficients of a polynomial expansion of the phase when the number of coefficients was correctly specified. A GA also successfully estimated the multiple p h e s of a segmented optical system analogous to the seven-mirror Systematic Image-Based Optical Alignment (SIBOA) testbed located at NASA s Marshall Space Flight Center. The SIBOA testbed was developed to investigate phase retrieval techniques. Tiphilt and piston motions of the mirrors accomplish phase corrections. A constant phase over each mirror can be achieved by an independent tip/tilt correction: the phase Conection term can then be factored out of the Discrete Fourier Tranform (DFT), greatly reducing computations.

Optical multiple-image encryption based on multiplane phase retrieval and interference

International Nuclear Information System (INIS)

Chen, Wen; Chen, Xudong

2011-01-01

In this paper, we propose a new method for optical multiple-image encryption based on multiplane phase retrieval and interference. An optical encoding system is developed in the Fresnel domain. A phase-only map is iteratively extracted based on a multiplane phase retrieval algorithm, and multiple plaintexts are simultaneously encrypted. Subsequently, the extracted phase-only map is further encrypted into two phase-only masks based on a non-iterative interference algorithm. During image decryption, the advantages and security of the proposed optical cryptosystem are analyzed. Numerical results are presented to demonstrate the validity of the proposed optical multiple-image encryption method

Phase unwinding for dictionary compression with multiple channel transmission in magnetic resonance fingerprinting.

Science.gov (United States)

Lattanzi, Riccardo; Zhang, Bei; Knoll, Florian; Assländer, Jakob; Cloos, Martijn A

2018-06-01

Magnetic Resonance Fingerprinting reconstructions can become computationally intractable with multiple transmit channels, if the B 1 + phases are included in the dictionary. We describe a general method that allows to omit the transmit phases. We show that this enables straightforward implementation of dictionary compression to further reduce the problem dimensionality. We merged the raw data of each RF source into a single k-space dataset, extracted the transceiver phases from the corresponding reconstructed images and used them to unwind the phase in each time frame. All phase-unwound time frames were combined in a single set before performing SVD-based compression. We conducted synthetic, phantom and in-vivo experiments to demonstrate the feasibility of SVD-based compression in the case of two-channel transmission. Unwinding the phases before SVD-based compression yielded artifact-free parameter maps. For fully sampled acquisitions, parameters were accurate with as few as 6 compressed time frames. SVD-based compression performed well in-vivo with highly under-sampled acquisitions using 16 compressed time frames, which reduced reconstruction time from 750 to 25min. Our method reduces the dimensions of the dictionary atoms and enables to implement any fingerprint compression strategy in the case of multiple transmit channels. Copyright © 2018 Elsevier Inc. All rights reserved.

Phase retrieval from coherent soft X-ray optics

International Nuclear Information System (INIS)

Peele, A.G.; Mancuso, A.P.; Tran, C.Q.; Paterson, D.; McNulty, I.; Hayes, J.P.; Nugent, K.A.

2005-01-01

We have recently probed the coherence of soft X-ray flux from a third generation synchrotron source [D. Paterson, B.E. Allman, P.J. McMahon, J. Lin, N. Moldovan, K.A. Nugent, I. McNulty, C.T. Chantler, C.C. Retsch, T.H.K. Irving, D.C. Mancini, Opt. Commun. 195 (2001) 79; C.Q. Tran, A.G. Peele, D. Paterson, A. Roberts, I. McNulty, K.A. Nugent, Opt. Lett. 30 (2005) 204.]. The 1-2 keV radiation exhibits transverse coherence lengths of 60 μm, which means that coherent optical effects may be observed in reasonably sized objects. We present experimental results demonstrating the creation of a phase singularity in a synchrotron beam by passing the beam through a phase mask at similarly low X-ray energies. This complements our earlier work at higher energies and demonstrates that we can now produce phase singularities across a range of energies where we have tested certain intensity-based phase recovery methods. These methods fail when the field contains phase singularities. We describe the X-ray optical vortex and outline its use as a pathological test object for phase retrieval methods. We also present recent progress towards overcoming the problem of phase retrieval in singular optics

Fractional Fourier domain optical image hiding using phase retrieval algorithm based on iterative nonlinear double random phase encoding.

Science.gov (United States)

Wang, Xiaogang; Chen, Wen; Chen, Xudong

2014-09-22

We present a novel image hiding method based on phase retrieval algorithm under the framework of nonlinear double random phase encoding in fractional Fourier domain. Two phase-only masks (POMs) are efficiently determined by using the phase retrieval algorithm, in which two cascaded phase-truncated fractional Fourier transforms (FrFTs) are involved. No undesired information disclosure, post-processing of the POMs or digital inverse computation appears in our proposed method. In order to achieve the reduction in key transmission, a modified image hiding method based on the modified phase retrieval algorithm and logistic map is further proposed in this paper, in which the fractional orders and the parameters with respect to the logistic map are regarded as encryption keys. Numerical results have demonstrated the feasibility and effectiveness of the proposed algorithms.

Multi-stage phase retrieval algorithm based upon the gyrator transform.

Science.gov (United States)

Rodrigo, José A; Duadi, Hamootal; Alieva, Tatiana; Zalevsky, Zeev

2010-01-18

The gyrator transform is a useful tool for optical information processing applications. In this work we propose a multi-stage phase retrieval approach based on this operation as well as on the well-known Gerchberg-Saxton algorithm. It results in an iterative algorithm able to retrieve the phase information using several measurements of the gyrator transform power spectrum. The viability and performance of the proposed algorithm is demonstrated by means of several numerical simulations and experimental results.

Multi-stage phase retrieval algorithm based upon the gyrator transform

OpenAIRE

Rodrigo Martín-Romo, José Augusto; Duadi, Hamootal; Alieva, Tatiana Krasheninnikova; Zalevsky, Zeev

2010-01-01

The gyrator transform is a useful tool for optical information processing applications. In this work we propose a multi-stage phase retrieval approach based on this operation as well as on the well-known Gerchberg-Saxton algorithm. It results in an iterative algorithm able to retrieve the phase information using several measurements of the gyrator transform power spectrum. The viability and performance of the proposed algorithm is demonstrated by means of several numerical simulations and exp...

Optically secured information retrieval using two authenticated phase-only masks.

Science.gov (United States)

Wang, Xiaogang; Chen, Wen; Mei, Shengtao; Chen, Xudong

2015-10-23

We propose an algorithm for jointly designing two phase-only masks (POMs) that allow for the encryption and noise-free retrieval of triple images. The images required for optical retrieval are first stored in quick-response (QR) codes for noise-free retrieval and flexible readout. Two sparse POMs are respectively calculated from two different images used as references for authentication based on modified Gerchberg-Saxton algorithm (GSA) and pixel extraction, and are then used as support constraints in a modified double-phase retrieval algorithm (MPRA), together with the above-mentioned QR codes. No visible information about the target images or the reference images can be obtained from each of these authenticated POMs. This approach allows users to authenticate the two POMs used for image reconstruction without visual observation of the reference images. It also allows user to friendly access and readout with mobile devices.

Qualification of a Null Lens Using Image-Based Phase Retrieval

Science.gov (United States)

Bolcar, Matthew R.; Aronstein, David L.; Hill, Peter C.; Smith, J. Scott; Zielinski, Thomas P.

2012-01-01

In measuring the figure error of an aspheric optic using a null lens, the wavefront contribution from the null lens must be independently and accurately characterized in order to isolate the optical performance of the aspheric optic alone. Various techniques can be used to characterize such a null lens, including interferometry, profilometry and image-based methods. Only image-based methods, such as phase retrieval, can measure the null-lens wavefront in situ - in single-pass, and at the same conjugates and in the same alignment state in which the null lens will ultimately be used - with no additional optical components. Due to the intended purpose of a Dull lens (e.g., to null a large aspheric wavefront with a near-equal-but-opposite spherical wavefront), characterizing a null-lens wavefront presents several challenges to image-based phase retrieval: Large wavefront slopes and high-dynamic-range data decrease the capture range of phase-retrieval algorithms, increase the requirements on the fidelity of the forward model of the optical system, and make it difficult to extract diagnostic information (e.g., the system F/#) from the image data. In this paper, we present a study of these effects on phase-retrieval algorithms in the context of a null lens used in component development for the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission. Approaches for mitigation are also discussed.

Model-based magnetization retrieval from holographic phase images

Energy Technology Data Exchange (ETDEWEB)

Röder, Falk, E-mail: f.roeder@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstr. 400, D-01328 Dresden (Germany); Triebenberg Labor, Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Vogel, Karin [Triebenberg Labor, Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Wolf, Daniel [Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstr. 400, D-01328 Dresden (Germany); Triebenberg Labor, Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Hellwig, Olav [Helmholtz-Zentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstr. 400, D-01328 Dresden (Germany); AG Magnetische Funktionsmaterialien, Institut für Physik, Technische Universität Chemnitz, D-09126 Chemnitz (Germany); HGST, A Western Digital Company, 3403 Yerba Buena Rd., San Jose, CA 95135 (United States); Wee, Sung Hun [HGST, A Western Digital Company, 3403 Yerba Buena Rd., San Jose, CA 95135 (United States); Wicht, Sebastian; Rellinghaus, Bernd [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany)

2017-05-15

The phase shift of the electron wave is a useful measure for the projected magnetic flux density of magnetic objects at the nanometer scale. More important for materials science, however, is the knowledge about the magnetization in a magnetic nano-structure. As demonstrated here, a dominating presence of stray fields prohibits a direct interpretation of the phase in terms of magnetization modulus and direction. We therefore present a model-based approach for retrieving the magnetization by considering the projected shape of the nano-structure and assuming a homogeneous magnetization therein. We apply this method to FePt nano-islands epitaxially grown on a SrTiO{sub 3} substrate, which indicates an inclination of their magnetization direction relative to the structural easy magnetic [001] axis. By means of this real-world example, we discuss prospects and limits of this approach. - Highlights: • Retrieval of the magnetization from holographic phase images. • Magnetostatic model constructed for a magnetic nano-structure. • Decomposition into homogeneously magnetized components. • Discretization of a each component by elementary cuboids. • Analytic solution for the phase of a magnetized cuboid considered. • Fitting a set of magnetization vectors to experimental phase images.

Grating-based x-ray differential phase contrast imaging with twin peaks in phase-stepping curves—phase retrieval and dewrapping

Energy Technology Data Exchange (ETDEWEB)

Yang, Yi; Xie, Huiqiao; Tang, Xiangyang, E-mail: xiangyang.tang@emory.edu [Imaging and Medical Physics, Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1701 Uppergate Dr., C-5018, Atlanta, Georgia 30322 (United States); Cai, Weixing [Department of Radiation Oncology, Brigham and Women’s Hospital Harvard Medical School, 75 Francis Street, Boston, Massachusetts 02115 (United States); Mao, Hui [Laboratory of Functional and Molecular Imaging and Nanomedicine, Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1841 Clifton Road NE, Atlanta, Georgia 30329 (United States)

2016-06-15

Purpose: X-ray differential phase contrast CT implemented with Talbot interferometry employs phase-stepping to extract information of x-ray attenuation, phase shift, and small-angle scattering. Since inaccuracy may exist in the absorption grating G{sub 2} due to an imperfect fabrication, the effective period of G{sub 2} can be as large as twice the nominal period, leading to a phenomenon of twin peaks that differ remarkably in their heights. In this work, the authors investigate how to retrieve and dewrap the phase signal from the phase-stepping curve (PSC) with the feature of twin peaks for x-ray phase contrast imaging. Methods: Based on the paraxial Fresnel–Kirchhoff theory, the analytical formulae to characterize the phenomenon of twin peaks in the PSC are derived. Then an approach to dewrap the retrieved phase signal by jointly using the phases of the first- and second-order Fourier components is proposed. Through an experimental investigation using a prototype x-ray phase contrast imaging system implemented with Talbot interferometry, the authors evaluate and verify the derived analytic formulae and the proposed approach for phase retrieval and dewrapping. Results: According to theoretical analysis, the twin-peak phenomenon in PSC is a consequence of combined effects, including the inaccuracy in absorption grating G{sub 2}, mismatch between phase grating and x-ray source spectrum, and finite size of x-ray tube’s focal spot. The proposed approach is experimentally evaluated by scanning a phantom consisting of organic materials and a lab mouse. The preliminary data show that compared to scanning G{sub 2} over only one single nominal period and correcting the measured phase signal with an intuitive phase dewrapping method that is being used in the field, stepping G{sub 2} over twice its nominal period and dewrapping the measured phase signal with the proposed approach can significantly improve the quality of x-ray differential phase contrast imaging in both

Phase Retrieval Techniques In Coordinates Measurement

International Nuclear Information System (INIS)

Harizanova, J. I.; Stoykova, E. V.; Sainov, V. C.

2007-01-01

A precise pattern projection profilometry for three-dimensional shape measurements with different methods of fringe generation is presented. The application of phase-shifting algorithm along with two-spacing illumination allow for phase retrieval and estimation of relative and absolute coordinates of the tested samples. The following experimental approaches for fringe generation are investigated: interferometric approach based on a classical Michelson interferometer, digital computation with a DMD projection and light modulation by a sinusoidal phase grating. The theoretical background, experimental results as well as comparison of the applied generation methods are analyzed. The obtained outcomes successfully display the applicability of this technique for surface profile measurement. The application of the proposed techniques for remote, non-destructive in-situ inspection of real objects from cultural heritage is discussed

Study of key technology of ghost imaging via compressive sensing for a phase object based on phase-shifting digital holography

International Nuclear Information System (INIS)

Leihong, Zhang; Dong, Liang; Bei, Li; Zilan, Pan; Dawei, Zhang; Xiuhua, Ma

2015-01-01

In this article, the algorithm of compressing sensing is used to improve the imaging resolution and realize ghost imaging via compressive sensing for a phase object based on the theoretical analysis of the lensless Fourier imaging of the algorithm of ghost imaging based on phase-shifting digital holography. The algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography uses the bucket detector to measure the total light intensity of the interference and the four-step phase-shifting method is used to obtain the total light intensity of differential interference light. The experimental platform is built based on the software simulation, and the experimental results show that the algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography can obtain the high-resolution phase distribution figure of the phase object. With the same sampling times, the phase clarity of the phase distribution figure obtained by the algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography is higher than that obtained by the algorithm of ghost imaging based on phase-shift digital holography. In this article, this study further extends the application range of ghost imaging and obtains the phase distribution of the phase object. (letter)

Compression of computer generated phase-shifting hologram sequence using AVC and HEVC

Science.gov (United States)

Xing, Yafei; Pesquet-Popescu, Béatrice; Dufaux, Frederic

2013-09-01

With the capability of achieving twice the compression ratio of Advanced Video Coding (AVC) with similar reconstruction quality, High Efficiency Video Coding (HEVC) is expected to become the newleading technique of video coding. In order to reduce the storage and transmission burden of digital holograms, in this paper we propose to use HEVC for compressing the phase-shifting digital hologram sequences (PSDHS). By simulating phase-shifting digital holography (PSDH) interferometry, interference patterns between illuminated three dimensional( 3D) virtual objects and the stepwise phase changed reference wave are generated as digital holograms. The hologram sequences are obtained by the movement of the virtual objects and compressed by AVC and HEVC. The experimental results show that AVC and HEVC are efficient to compress PSDHS, with HEVC giving better performance. Good compression rate and reconstruction quality can be obtained with bitrate above 15000kbps.

Induction of a shorter compression phase is correlated with a deeper chest compression during metronome-guided cardiopulmonary resuscitation: a manikin study.

Science.gov (United States)

Chung, Tae Nyoung; Bae, Jinkun; Kim, Eui Chung; Cho, Yun Kyung; You, Je Sung; Choi, Sung Wook; Kim, Ok Jun

2013-07-01

Recent studies have shown that there may be an interaction between duty cycle and other factors related to the quality of chest compression. Duty cycle represents the fraction of compression phase. We aimed to investigate the effect of shorter compression phase on average chest compression depth during metronome-guided cardiopulmonary resuscitation. Senior medical students performed 12 sets of chest compressions following the guiding sounds, with three down-stroke patterns (normal, fast and very fast) and four rates (80, 100, 120 and 140 compressions/min) in random sequence. Repeated-measures analysis of variance was used to compare the average chest compression depth and duty cycle among the trials. The average chest compression depth increased and the duty cycle decreased in a linear fashion as the down-stroke pattern shifted from normal to very fast (pmetronome-guided cardiopulmonary resuscitation.

Phase retrieval with the reverse projection method in the presence of object's scattering

International Nuclear Information System (INIS)

Wang, Zhili; Gao, Kun; Wang, Dajiang

2017-01-01

X-ray grating interferometry can provide substantially increased contrast over traditional attenuation-based techniques in biomedical applications, and therefore novel and complementary information. Recently, special attention has been paid to quantitative phase retrieval in X-ray grating interferometry, which is mandatory to perform phase tomography, to achieve material identification, etc. An innovative approach, dubbed “Reverse Projection” (RP), has been developed for quantitative phase retrieval. The RP method abandons grating scanning completely, and is thus advantageous in terms of higher efficiency and reduced radiation damage. Therefore, it is expected that this novel method would find its potential in preclinical and clinical implementations. Strictly speaking, the reverse projection method is applicable for objects exhibiting only absorption and refraction. In this contribution, we discuss the phase retrieval with the reverse projection method for general objects with absorption, refraction and scattering simultaneously. Especially, we investigate the influence of the object's scattering on the retrieved refraction signal. Both theoretical analysis and numerical experiments are performed. The results show that the retrieved refraction signal is the product of object's refraction and scattering signals for small values. In the case of a strong scattering, the reverse projection method cannot provide reliable phase retrieval. Those presented results will guide the use of the reverse projection method for future practical applications, and help to explain some possible artifacts in the retrieved images and/or reconstructed slices. - Highlights: • Accurate phase retrieval by the reverse projection method without object's scattering. • Retrieved refraction signal contaminated by the object's scattering. • Refraction signal underestimated by the reverse projection method. • Guide the use of the reverse projection method for

High sensitivity phase retrieval method in grating-based x-ray phase contrast imaging

Energy Technology Data Exchange (ETDEWEB)

Wu, Zhao; Gao, Kun; Chen, Jian; Wang, Dajiang; Wang, Shenghao; Chen, Heng; Bao, Yuan; Shao, Qigang; Wang, Zhili, E-mail: wangnsrl@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China); Zhang, Kai [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Zhu, Peiping; Wu, Ziyu, E-mail: wuzy@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China and Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2015-02-15

Purpose: Grating-based x-ray phase contrast imaging is considered as one of the most promising techniques for future medical imaging. Many different methods have been developed to retrieve phase signal, among which the phase stepping (PS) method is widely used. However, further practical implementations are hindered, due to its complex scanning mode and high radiation dose. In contrast, the reverse projection (RP) method is a novel fast and low dose extraction approach. In this contribution, the authors present a quantitative analysis of the noise properties of the refraction signals retrieved by the two methods and compare their sensitivities. Methods: Using the error propagation formula, the authors analyze theoretically the signal-to-noise ratios (SNRs) of the refraction images retrieved by the two methods. Then, the sensitivities of the two extraction methods are compared under an identical exposure dose. Numerical experiments are performed to validate the theoretical results and provide some quantitative insight. Results: The SNRs of the two methods are both dependent on the system parameters, but in different ways. Comparison between their sensitivities reveals that for the refraction signal, the RP method possesses a higher sensitivity, especially in the case of high visibility and/or at the edge of the object. Conclusions: Compared with the PS method, the RP method has a superior sensitivity and provides refraction images with a higher SNR. Therefore, one can obtain highly sensitive refraction images in grating-based phase contrast imaging. This is very important for future preclinical and clinical implementations.

High sensitivity phase retrieval method in grating-based x-ray phase contrast imaging

International Nuclear Information System (INIS)

Wu, Zhao; Gao, Kun; Chen, Jian; Wang, Dajiang; Wang, Shenghao; Chen, Heng; Bao, Yuan; Shao, Qigang; Wang, Zhili; Zhang, Kai; Zhu, Peiping; Wu, Ziyu

2015-01-01

Purpose: Grating-based x-ray phase contrast imaging is considered as one of the most promising techniques for future medical imaging. Many different methods have been developed to retrieve phase signal, among which the phase stepping (PS) method is widely used. However, further practical implementations are hindered, due to its complex scanning mode and high radiation dose. In contrast, the reverse projection (RP) method is a novel fast and low dose extraction approach. In this contribution, the authors present a quantitative analysis of the noise properties of the refraction signals retrieved by the two methods and compare their sensitivities. Methods: Using the error propagation formula, the authors analyze theoretically the signal-to-noise ratios (SNRs) of the refraction images retrieved by the two methods. Then, the sensitivities of the two extraction methods are compared under an identical exposure dose. Numerical experiments are performed to validate the theoretical results and provide some quantitative insight. Results: The SNRs of the two methods are both dependent on the system parameters, but in different ways. Comparison between their sensitivities reveals that for the refraction signal, the RP method possesses a higher sensitivity, especially in the case of high visibility and/or at the edge of the object. Conclusions: Compared with the PS method, the RP method has a superior sensitivity and provides refraction images with a higher SNR. Therefore, one can obtain highly sensitive refraction images in grating-based phase contrast imaging. This is very important for future preclinical and clinical implementations

Constructing a unique two-phase compressibility factor model for lean gas condensates

Energy Technology Data Exchange (ETDEWEB)

Moayyedi, Mahmood; Gharesheikhlou, Aliashghar [Research Institute of Petroleum Industry (RIPI), Tehran (Iran, Islamic Republic of); Azamifard, Arash; Mosaferi, Emadoddin [Amirkabir University of Technology (AUT), Tehran (Iran, Islamic Republic of)

2015-02-15

Generating a reliable experimental model for two-phase compressibility factor in lean gas condensate reservoirs has always been demanding, but it was neglected due to lack of required experimental data. This study presents the main results of constructing the first two-phase compressibility factor model that is completely valid for Iranian lean gas condensate reservoirs. Based on a wide range of experimental data bank for Iranian lean gas condensate reservoirs, a unique two-phase compressibility factor model was generated using design of experiments (DOE) method and neural network technique (ANN). Using DOE, a swift cubic response surface model was generated for two-phase compressibility factor as a function of some selected fluid parameters for lean gas condensate fluids. The proposed DOE and ANN models were finally validated using four new independent data series. The results showed that there is a good agreement between experimental data and the proposed models. In the end, a detailed comparison was made between the results of proposed models.

Constructing a unique two-phase compressibility factor model for lean gas condensates

International Nuclear Information System (INIS)

Moayyedi, Mahmood; Gharesheikhlou, Aliashghar; Azamifard, Arash; Mosaferi, Emadoddin

2015-01-01

Generating a reliable experimental model for two-phase compressibility factor in lean gas condensate reservoirs has always been demanding, but it was neglected due to lack of required experimental data. This study presents the main results of constructing the first two-phase compressibility factor model that is completely valid for Iranian lean gas condensate reservoirs. Based on a wide range of experimental data bank for Iranian lean gas condensate reservoirs, a unique two-phase compressibility factor model was generated using design of experiments (DOE) method and neural network technique (ANN). Using DOE, a swift cubic response surface model was generated for two-phase compressibility factor as a function of some selected fluid parameters for lean gas condensate fluids. The proposed DOE and ANN models were finally validated using four new independent data series. The results showed that there is a good agreement between experimental data and the proposed models. In the end, a detailed comparison was made between the results of proposed models

Internal loading of an inhomogeneous compressible Earth with phase boundaries

Science.gov (United States)

Defraigne, P.; Dehant, V.; Wahr, J. M.

1996-01-01

The geoid and the boundary topography caused by mass loads inside the earth were estimated. It is shown that the estimates are affected by compressibility, by a radially varying density distribution, and by the presence of phase boundaries with density discontinuities. The geoid predicted in the chemical boundary case is 30 to 40 percent smaller than that predicted in the phase case. The effects of compressibility and radially varying density are likely to be small. The inner core-outer core topography for loading inside the mantle and for loading inside the inner core were computed.

Two-level image authentication by two-step phase-shifting interferometry and compressive sensing

Science.gov (United States)

Zhang, Xue; Meng, Xiangfeng; Yin, Yongkai; Yang, Xiulun; Wang, Yurong; Li, Xianye; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi

2018-01-01

A two-level image authentication method is proposed; the method is based on two-step phase-shifting interferometry, double random phase encoding, and compressive sensing (CS) theory, by which the certification image can be encoded into two interferograms. Through discrete wavelet transform (DWT), sparseness processing, Arnold transform, and data compression, two compressed signals can be generated and delivered to two different participants of the authentication system. Only the participant who possesses the first compressed signal attempts to pass the low-level authentication. The application of Orthogonal Match Pursuit CS algorithm reconstruction, inverse Arnold transform, inverse DWT, two-step phase-shifting wavefront reconstruction, and inverse Fresnel transform can result in the output of a remarkable peak in the central location of the nonlinear correlation coefficient distributions of the recovered image and the standard certification image. Then, the other participant, who possesses the second compressed signal, is authorized to carry out the high-level authentication. Therefore, both compressed signals are collected to reconstruct the original meaningful certification image with a high correlation coefficient. Theoretical analysis and numerical simulations verify the feasibility of the proposed method.

Phase retrieval from a single fringe pattern by using empirical wavelet transform

International Nuclear Information System (INIS)

Guo, Xiaopeng; Zhao, Hong; Wang, Xin

2015-01-01

Phase retrieval from a single fringe pattern is one of the key tasks in optical metrology. In this paper, we present a new method for phase retrieval from a single fringe pattern based on empirical wavelet transform. In the proposed method, a fringe pattern can be effectively divided into three components: nonuniform background, fringes and random noise, which are described in different sub-pass. So the phase distribution information can be robustly extracted from fringes representing a fundamental frequency component. In simulation and a practical projection fringes test, the performance of the present method is successfully verified by comparing with the conventional wavelet transform method in terms of both image quality and phase estimation errors. (paper)

Quantitative evaluation of a single-distance phase-retrieval method applied on in-line phase-contrast images of a mouse lung

International Nuclear Information System (INIS)

Mohammadi, Sara; Larsson, Emanuel; Alves, Frauke; Dal Monego, Simeone; Biffi, Stefania; Garrovo, Chiara; Lorenzon, Andrea; Tromba, Giuliana; Dullin, Christian

2014-01-01

Quantitative analysis concerning the application of a single-distance phase-retrieval algorithm on in-line phase-contrast images of a mouse lung at different sample-to-detector distances is presented. Propagation-based X-ray phase-contrast computed tomography (PBI) has already proven its potential in a great variety of soft-tissue-related applications including lung imaging. However, the strong edge enhancement, caused by the phase effects, often hampers image segmentation and therefore the quantitative analysis of data sets. Here, the benefits of applying single-distance phase retrieval prior to the three-dimensional reconstruction (PhR) are discussed and quantified compared with three-dimensional reconstructions of conventional PBI data sets in terms of contrast-to-noise ratio (CNR) and preservation of image features. The PhR data sets show more than a tenfold higher CNR and only minor blurring of the edges when compared with PBI in a predominately absorption-based set-up. Accordingly, phase retrieval increases the sensitivity and provides more functionality in computed tomography imaging

Phase Retrieval Using a Genetic Algorithm on the Systematic Image-Based Optical Alignment Testbed

Science.gov (United States)

Taylor, Jaime R.

2003-01-01

NASA s Marshall Space Flight Center s Systematic Image-Based Optical Alignment (SIBOA) Testbed was developed to test phase retrieval algorithms and hardware techniques. Individuals working with the facility developed the idea of implementing phase retrieval by breaking the determination of the tip/tilt of each mirror apart from the piston motion (or translation) of each mirror. Presented in this report is an algorithm that determines the optimal phase correction associated only with the piston motion of the mirrors. A description of the Phase Retrieval problem is first presented. The Systematic Image-Based Optical Alignment (SIBOA) Testbeb is then described. A Discrete Fourier Transform (DFT) is necessary to transfer the incoming wavefront (or estimate of phase error) into the spatial frequency domain to compare it with the image. A method for reducing the DFT to seven scalar/matrix multiplications is presented. A genetic algorithm is then used to search for the phase error. The results of this new algorithm on a test problem are presented.

High speed phase retrieval of in-line holograms by the assistance of corresponding off-axis holograms.

Science.gov (United States)

Orzó, László

2015-06-29

Retrieving correct phase information from an in-line hologram is difficult as the object wave field and the diffractions of the zero order and the conjugate object term overlap. The existing iterative numerical phase retrieval methods are slow, especially in the case of high Fresnel number systems. Conversely, the reconstruction of the object wave field from an off-axis hologram is simple, but due to the applied spatial frequency filtering the achievable resolution is confined. Here, a new, high-speed algorithm is introduced that efficiently incorporates the data of an auxiliary off-axis hologram in the phase retrieval of the corresponding in-line hologram. The efficiency of the introduced combined phase retrieval method is demonstrated by simulated and measured holograms.

A new method for information retrieval in two-dimensional grating-based X-ray phase contrast imaging

International Nuclear Information System (INIS)

Wang Zhi-Li; Gao Kun; Chen Jian; Ge Xin; Tian Yang-Chao; Wu Zi-Yu; Zhu Pei-Ping

2012-01-01

Grating-based X-ray phase contrast imaging has been demonstrated to be an extremely powerful phase-sensitive imaging technique. By using two-dimensional (2D) gratings, the observable contrast is extended to two refraction directions. Recently, we have developed a novel reverse-projection (RP) method, which is capable of retrieving the object information efficiently with one-dimensional (1D) grating-based phase contrast imaging. In this contribution, we present its extension to the 2D grating-based X-ray phase contrast imaging, named the two-dimensional reverse-projection (2D-RP) method, for information retrieval. The method takes into account the nonlinear contributions of two refraction directions and allows the retrieval of the absorption, the horizontal and the vertical refraction images. The obtained information can be used for the reconstruction of the three-dimensional phase gradient field, and for an improved phase map retrieval and reconstruction. Numerical experiments are carried out, and the results confirm the validity of the 2D-RP method

Subset-sum phase transitions and data compression

Science.gov (United States)

Merhav, Neri

2011-09-01

We propose a rigorous analysis approach for the subset-sum problem in the context of lossless data compression, where the phase transition of the subset-sum problem is directly related to the passage between ambiguous and non-ambiguous decompression, for a compression scheme that is based on specifying the sequence composition. The proposed analysis lends itself to straightforward extensions in several directions of interest, including non-binary alphabets, incorporation of side information at the decoder (Slepian-Wolf coding), and coding schemes based on multiple subset sums. It is also demonstrated that the proposed technique can be used to analyze the critical behavior in a more involved situation where the sequence composition is not specified by the encoder.

Optical image encryption using password key based on phase retrieval algorithm

Science.gov (United States)

Zhao, Tieyu; Ran, Qiwen; Yuan, Lin; Chi, Yingying; Ma, Jing

2016-04-01

A novel optical image encryption system is proposed using password key based on phase retrieval algorithm (PRA). In the encryption process, a shared image is taken as a symmetric key and the plaintext is encoded into the phase-only mask based on the iterative PRA. The linear relationship between the plaintext and ciphertext is broken using the password key, which can resist the known plaintext attack. The symmetric key and the retrieved phase are imported into the input plane and Fourier plane of 4f system during the decryption, respectively, so as to obtain the plaintext on the CCD. Finally, we analyse the key space of the password key, and the results show that the proposed scheme can resist a brute force attack due to the flexibility of the password key.

Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC)

Science.gov (United States)

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2018-01-01

This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud temperature threshold based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (clouds the error is mostly limited to within 10%, although for thin clouds (COT cloud masking and cloud temperature retrievals are not considered in this study. PMID:29619116

Test of a method for phase retrieval in HRTEM

International Nuclear Information System (INIS)

Beeching, M.J.; Spargo, A.E.C.

1992-01-01

Several methods of phase retrieval from the high resolution transmission electron microscopy image intensity distributions have been proposed but no standard method has emerged. The results achieved using a technique based on a development of the focus variation method, are reported. The dependence of the retrieved wavefunction on various experimental parameters is investigated and the method tested using computer simulated images. The method is shown to be useful in finding the complex wavefield at the exit surface of the specimen but the relationship of this to the specimen structure is considered as a separate issue. 1 ref., 3 figs

Multiwavelength Absolute Phase Retrieval from Noisy Diffractive Patterns: Wavelength Multiplexing Algorithm

Directory of Open Access Journals (Sweden)

Vladimir Katkovnik

2018-05-01

Full Text Available We study the problem of multiwavelength absolute phase retrieval from noisy diffraction patterns. The system is lensless with multiwavelength coherent input light beams and random phase masks applied for wavefront modulation. The light beams are formed by light sources radiating all wavelengths simultaneously. A sensor equipped by a Color Filter Array (CFA is used for spectral measurement registration. The developed algorithm targeted on optimal phase retrieval from noisy observations is based on maximum likelihood technique. The algorithm is specified for Poissonian and Gaussian noise distributions. One of the key elements of the algorithm is an original sparse modeling of the multiwavelength complex-valued wavefronts based on the complex-domain block-matching 3D filtering. Presented numerical experiments are restricted to noisy Poissonian observations. They demonstrate that the developed algorithm leads to effective solutions explicitly using the sparsity for noise suppression and enabling accurate reconstruction of absolute phase of high-dynamic range.

Phase retrieval from reflective fringe patterns of double-sided transparent objects

International Nuclear Information System (INIS)

Huang, Lei; Asundi, Anand Krishna

2012-01-01

‘Ghosted’ fringe patterns simultaneously reflected from both the upper and lower sides of a transparent target in the fringe reflection technique are captured for transparent surface 3D shape measurement, but the phase retrieval from the captured ‘ghosted’ fringe patterns is still not solved. A novel method is proposed to solve this issue by using two sets of phase-shifted fringe patterns with slightly different frequencies. The nonlinear least-squares method is used to estimate the fringe phase and modulation from both front and rear interfaces. Several simulations are done to show the feasibility of the proposed method. The influence of fringe noise on the algorithm is studied as well, which indicates that the proposed method is able to retrieve the phase from double-sided reflective fringe patterns with fringe noise equivalent to that in practical measurements. The merits and limitations of the method are discussed and recommendations for future studies are made. (paper)

Optical image encryption based on phase retrieval combined with three-dimensional particle-like distribution

International Nuclear Information System (INIS)

Chen, Wen; Chen, Xudong; Sheppard, Colin J R

2012-01-01

We propose a new phase retrieval algorithm for optical image encryption in three-dimensional (3D) space. The two-dimensional (2D) plaintext is considered as a series of particles distributed in 3D space, and an iterative phase retrieval algorithm is developed to encrypt the series of particles into phase-only masks. The feasibility and effectiveness of the proposed method are demonstrated by a numerical experiment, and the advantages and security of the proposed optical cryptosystems are also analyzed and discussed. (paper)

SIMULATION OF MULTIPLEXING OF TWO PHASE SOIL IN CASE OF COMPRESSION COMPRESSION

Directory of Open Access Journals (Sweden)

G. E. Agakhanov

2016-01-01

Full Text Available Aim.The article is devoted to solving the problem of finding metodoa seal a two phase soil layer under compression compression uniformly distributed load.Methods.On estimated model of a continuous isotropic body with linear and hereditary creep in case of invariance of the environment and a persistence of coefficient of Poisson in time, and also taking into account different resilience of a skeleton of soil when multiplexing and demultiplexing the decision of the task of multiplexing of a layer of two-phase soil in case of compression is received by a uniformly distributed load. Special cases of the intense deformed status are considered.Results.The analysis of the received decision shows that in case of a persistence in time of coefficient of Poisson of the environment, creep doesn't influence tension, and only affects deformation or relocation (settling that corresponds to earlier set provisions. In case of a persistence of coefficient of Poisson the intense deformed status of the environment can be determined also by method of elastic analogy, solving the appropriate uprugomgnovenny problem. The solution of the equation for pore pressure is executed by Fourier method. According to the received analytical decision the flowchart and the program in Matlab packet with use of the built-in programming language of the Matlab system is made.Conclusion. For two options of conditions of drainage calculation of function of pore pressure, function of a side raspor and level of consolidation of a layer taking into account and without creep is executed and their surfaces of distribution and a graphics of change are constructed.

Retrieval of Ice Cloud Properties Using Variable Phase Functions

Science.gov (United States)

Heck, Patrick W.; Minnis, Patrick; Yang, Ping; Chang, Fu-Lung; Palikonda, Rabindra; Arduini, Robert F.; Sun-Mack, Sunny

2009-03-01

An enhancement to NASA Langley's Visible Infrared Solar-infrared Split-window Technique (VISST) is developed to identify and account for situations when errors are induced by using smooth ice crystals. The retrieval scheme incorporates new ice cloud phase functions that utilize hexagonal crystals with roughened surfaces. In some situations, cloud optical depths are reduced, hence, cloud height is increased. Cloud effective particle size also changes with the roughened ice crystal models which results in varied effects on the calculation of ice water path. Once validated and expanded, the new approach will be integrated in the CERES MODIS algorithm and real-time retrievals at Langley.

Phase retrieval via incremental truncated amplitude flow algorithm

Science.gov (United States)

Zhang, Quanbing; Wang, Zhifa; Wang, Linjie; Cheng, Shichao

2017-10-01

This paper considers the phase retrieval problem of recovering the unknown signal from the given quadratic measurements. A phase retrieval algorithm based on Incremental Truncated Amplitude Flow (ITAF) which combines the ITWF algorithm and the TAF algorithm is proposed. The proposed ITAF algorithm enhances the initialization by performing both of the truncation methods used in ITWF and TAF respectively, and improves the performance in the gradient stage by applying the incremental method proposed in ITWF to the loop stage of TAF. Moreover, the original sampling vector and measurements are preprocessed before initialization according to the variance of the sensing matrix. Simulation experiments verified the feasibility and validity of the proposed ITAF algorithm. The experimental results show that it can obtain higher success rate and faster convergence speed compared with other algorithms. Especially, for the noiseless random Gaussian signals, ITAF can recover any real-valued signal accurately from the magnitude measurements whose number is about 2.5 times of the signal length, which is close to the theoretic limit (about 2 times of the signal length). And it usually converges to the optimal solution within 20 iterations which is much less than the state-of-the-art algorithms.

Hybrid iterative phase retrieval algorithm based on fusion of intensity information in three defocused planes.

Science.gov (United States)

Zeng, Fa; Tan, Qiaofeng; Yan, Yingbai; Jin, Guofan

2007-10-01

Study of phase retrieval technology is quite meaningful, for its wide applications related to many domains, such as adaptive optics, detection of laser quality, precise measurement of optical surface, and so on. Here a hybrid iterative phase retrieval algorithm is proposed, based on fusion of the intensity information in three defocused planes. First the conjugate gradient algorithm is adapted to achieve a coarse solution of phase distribution in the input plane; then the iterative angular spectrum method is applied in succession for better retrieval result. This algorithm is still applicable even when the exact shape and size of the aperture in the input plane are unknown. Moreover, this algorithm always exhibits good convergence, i.e., the retrieved results are insensitive to the chosen positions of the three defocused planes and the initial guess of complex amplitude in the input plane, which has been proved by both simulations and further experiments.

International workshop on phase retrieval and coherent scattering. Coherence 2005

International Nuclear Information System (INIS)

Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc'h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B.

2005-01-01

The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters

International workshop on phase retrieval and coherent scattering. Coherence 2005

Energy Technology Data Exchange (ETDEWEB)

Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc' h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B

2005-07-01

The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters.

Retrieving 3D Wind Field from Phased Array Radar Rapid Scans

Directory of Open Access Journals (Sweden)

Xiaobin Qiu

2013-01-01

Full Text Available The previous two-dimensional simple adjoint method for retrieving horizontal wind field from a time sequence of single-Doppler scans of reflectivity and/or radial velocity is further developed into a new method to retrieve both horizontal and vertical winds at high temporal and spatial resolutions. This new method performs two steps. First, the horizontal wind field is retrieved on the conical surface at each tilt (elevation angle of radar scan. Second, the vertical velocity field is retrieved in a vertical cross-section along the radar beam with the horizontal velocity given from the first step. The method is applied to phased array radar (PAR rapid scans of the storm winds and reflectivity in a strong microburst event and is shown to be able to retrieve the three-dimensional wind field around a targeted downdraft within the storm that subsequently produced a damaging microburst. The method is computationally very efficient and can be used for real-time applications with PAR rapid scans.

Linear iterative near-field phase retrieval (LIPR) for dual-energy x-ray imaging and material discrimination.

Science.gov (United States)

Li, Heyang Thomas; Kingston, Andrew M; Myers, Glenn R; Beeching, Levi; Sheppard, Adrian P

2018-01-01

Near-field x-ray refraction (phase) contrast is unavoidable in many lab-based micro-CT imaging systems. Quantitative analysis of x-ray refraction (a.k.a. phase retrieval) is in general an under-constrained problem. Regularizing assumptions may not hold true for interesting samples; popular single-material methods are inappropriate for heterogeneous samples, leading to undesired blurring and/or over-sharpening. In this paper, we constrain and solve the phase-retrieval problem for heterogeneous objects, using the Alvarez-Macovski model for x-ray attenuation. Under this assumption we neglect Rayleigh scattering and pair production, considering only Compton scattering and the photoelectric effect. We formulate and test the resulting method to extract the material properties of density and atomic number from single-distance, dual-energy imaging of both strongly and weakly attenuating multi-material objects with polychromatic x-ray spectra. Simulation and experimental data are used to compare our proposed method with the Paganin single-material phase-retrieval algorithm, and an innovative interpretation of the data-constrained modeling phase-retrieval technique.

On the phase transition nature in compressible Ising models

International Nuclear Information System (INIS)

Ota, A.T.

1985-01-01

The phase transition phenomenon is analysed in a compressible ferromagnetic Ising model at null field, through the mean-field approximation. The model studied is d-dimensional under the magnetic point of view and one-dimensional under the elastic point of view. This is achieved keeping the compressive interactions among the ions and rejecting annealing forces completely. The exchange parameter J is linear and the elastic potential quadratic in relation to the microscopic shifts of the lattice. In the one-dimensional case, this model shows no phase transition. In the two-dimensional case, the role of the S i spin of the i-the ion is crucial: a) for spin 1/2 the transitions are of second order; b) for spin 1, desides the second order transitions there is a three-critical point and a first-order transitions line. (L.C.) [pt

Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC).

Science.gov (United States)

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2016-01-01

This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud temperature threshold based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (< 2%) due to the particle size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10%, although for thin clouds (COT < 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study.

Diamond to β-Sn phase transition of silicon under hydrostatic and nonhydrostatic compressions

International Nuclear Information System (INIS)

Durandurdu, Murat

2008-01-01

We have carried out constant pressure ab initio simulations to study the pressure-induced phase transition of silicon. The diamond to β-Sn phase change under hydrostatic pressure is successfully observed in the simulation. The transformation is based on a fourfold coordinated tetragonal intermediate state having the space group I4 1 /amd. The energy barrier for the transformation is calculated to be about 0.35 eV/atom. Additionally, we investigate the influence of nonhydrostatic compressions on the phase transition of silicon and find that up to 20% stress deviations, silicon converts to a β-Sn structure with a reduced transition pressure. The triaxial compressions cause more reduction in the transition pressure than the uniaxial compressions. The transformation mechanism is practically identical under both hydrostatic and nonhydrostatic conditions

Compressive deformation of liquid phase-sintered porous silicon carbide ceramics

Directory of Open Access Journals (Sweden)

Taro Shimonosono

2014-12-01

Full Text Available Porous silicon carbide ceramics were fabricated by liquid phase sintering with 1 wt% Al2O3–1 wt% Y2O3 additives during hot-pressing at 1400–1900 °C. The longitudinal strain at compressive fracture increased at a higher porosity and was larger than the lateral strain. The compressive Young's modulus and the strain at fracture depended on the measured direction, and increased with the decreased specific surface area due to the formation of grain boundary. However, the compressive strength and the fracture energy were not sensitive to the measured direction. The compressive strength of a porous SiC compact increased with increasing grain boundary area. According to the theoretical modeling of the strength–grain boundary area relation, it is interpreted that the grain boundary of a porous SiC compact is fractured by shear deformation rather than by compressive deformation.

Performance of Ruecking's Word-compression Method When Applied to Machine Retrieval from a Library Catalog

Directory of Open Access Journals (Sweden)

Ben-Ami Lipetz

1969-12-01

Full Text Available F. H. Ruecking's word-compression algorithm for retrieval of bibliographic data from computer stores was tested for performance in matching user-supplied, unedited bibliographic data to the bibliographic data contained in a library catalog. The algorithm was tested by manual simulation, using data derived from 126 case studies of successful manual searches of the card catalog at Sterling Memorial Library, Yale University. The algorithm achieved 70% recall in comparison to conventional searching. Its accepta- bility as a substitute for conventional catalog searching methods is ques- tioned unless recall performance can be improved, either by use of the algorithm alone or in combination with other algorithms.

Three-dimensional imaging using phase retrieval with two focus planes

Science.gov (United States)

Ilovitsh, Tali; Ilovitsh, Asaf; Weiss, Aryeh; Meir, Rinat; Zalevsky, Zeev

2016-03-01

This work presents a technique for a full 3D imaging of biological samples tagged with gold-nanoparticles (GNPs) using only two images, rather than many images per volume as is currently needed for 3D optical sectioning microscopy. The proposed approach is based on the Gerchberg-Saxton (GS) phase retrieval algorithm. The reconstructed field is free space propagated to all other focus planes using post processing, and the 2D z-stack is merged to create a 3D image of the sample with high fidelity. Because we propose to apply the phase retrieving on nano particles, the regular ambiguities typical to the Gerchberg-Saxton algorithm, are eliminated. In addition, since the method requires the capturing of two images only, it can be suitable for 3D live cell imaging. The proposed concept is presented and validated both on simulated data as well as experimentally.

Phase-Retrieval Uncertainty Estimation and Algorithm Comparison for the JWST-ISIM Test Campaign

Science.gov (United States)

Aronstein, David L.; Smith, J. Scott

2016-01-01

Phase retrieval, the process of determining the exitpupil wavefront of an optical instrument from image-plane intensity measurements, is the baseline methodology for characterizing the wavefront for the suite of science instruments (SIs) in the Integrated Science Instrument Module (ISIM) for the James Webb Space Telescope (JWST). JWST is a large, infrared space telescope with a 6.5-meter diameter primary mirror. JWST is currently NASA's flagship mission and will be the premier space observatory of the next decade. ISIM contains four optical benches with nine unique instruments, including redundancies. ISIM was characterized at the Goddard Space Flight Center (GSFC) in Greenbelt, MD in a series of cryogenic vacuum tests using a telescope simulator. During these tests, phase-retrieval algorithms were used to characterize the instruments. The objective of this paper is to describe the Monte-Carlo simulations that were used to establish uncertainties (i.e., error bars) for the wavefronts of the various instruments in ISIM. Multiple retrieval algorithms were used in the analysis of ISIM phase-retrieval focus-sweep data, including an iterativetransform algorithm and a nonlinear optimization algorithm. These algorithms emphasize the recovery of numerous optical parameters, including low-order wavefront composition described by Zernike polynomial terms and high-order wavefront described by a point-by-point map, location of instrument best focus, focal ratio, exit-pupil amplitude, the morphology of any extended object, and optical jitter. The secondary objective of this paper is to report on the relative accuracies of these algorithms for the ISIM instrument tests, and a comparison of their computational complexity and their performance on central and graphical processing unit clusters. From a phase-retrieval perspective, the ISIM test campaign includes a variety of source illumination bandwidths, various image-plane sampling criteria above and below the Nyquist- Shannon

Near-field ptychography: phase retrieval for inline holography using a structured illumination.

Science.gov (United States)

Stockmar, Marco; Cloetens, Peter; Zanette, Irene; Enders, Bjoern; Dierolf, Martin; Pfeiffer, Franz; Thibault, Pierre

2013-01-01

Inline holography is a common phase-contrast imaging method which uses free-space propagation to encode the phase signal into measured intensities. However, quantitative retrieval of the sample's image remains challenging, imposing constraints on the nature of the sample or on the propagation distance. Here, we present a way of simultaneously retrieving the sample's complex-valued transmission function and the incident illumination function from near-field diffraction patterns. The procedure relies on the measurement diversity created by lateral translations of the sample with respect to a structured illumination. The reconstruction approach, in essence identical to that employed in ptychography, is applied to hard X-ray synchrotron measurements and to simulations. Compared to other inline holography techniques, we expect near-field ptychography to reduce reconstruction artefacts by factoring out wavefront imperfections and relaxing constraints on the sample's scattering properties, thus ultimately improving the robustness of propagation-based X-ray phase tomography.

Intelligent fuzzy approach for fast fractal image compression

Science.gov (United States)

Nodehi, Ali; Sulong, Ghazali; Al-Rodhaan, Mznah; Al-Dhelaan, Abdullah; Rehman, Amjad; Saba, Tanzila

2014-12-01

Fractal image compression (FIC) is recognized as a NP-hard problem, and it suffers from a high number of mean square error (MSE) computations. In this paper, a two-phase algorithm was proposed to reduce the MSE computation of FIC. In the first phase, based on edge property, range and domains are arranged. In the second one, imperialist competitive algorithm (ICA) is used according to the classified blocks. For maintaining the quality of the retrieved image and accelerating algorithm operation, we divided the solutions into two groups: developed countries and undeveloped countries. Simulations were carried out to evaluate the performance of the developed approach. Promising results thus achieved exhibit performance better than genetic algorithm (GA)-based and Full-search algorithms in terms of decreasing the number of MSE computations. The number of MSE computations was reduced by the proposed algorithm for 463 times faster compared to the Full-search algorithm, although the retrieved image quality did not have a considerable change.

Fourier phase retrieval with a single mask by Douglas-Rachford algorithms.

Science.gov (United States)

Chen, Pengwen; Fannjiang, Albert

2018-05-01

The Fourier-domain Douglas-Rachford (FDR) algorithm is analyzed for phase retrieval with a single random mask. Since the uniqueness of phase retrieval solution requires more than a single oversampled coded diffraction pattern, the extra information is imposed in either of the following forms: 1) the sector condition on the object; 2) another oversampled diffraction pattern, coded or uncoded. For both settings, the uniqueness of projected fixed point is proved and for setting 2) the local, geometric convergence is derived with a rate given by a spectral gap condition. Numerical experiments demonstrate global, power-law convergence of FDR from arbitrary initialization for both settings as well as for 3 or more coded diffraction patterns without oversampling. In practice, the geometric convergence can be recovered from the power-law regime by a simple projection trick, resulting in highly accurate reconstruction from generic initialization.

Generalised synchronisation of spatiotemporal chaos using feedback control method and phase compression

International Nuclear Information System (INIS)

Xing-Yuan, Wang; Na, Zhang

2010-01-01

Coupled map lattices are taken as examples to study the synchronisation of spatiotemporal chaotic systems. First, a generalised synchronisation of two coupled map lattices is realised through selecting an appropriate feedback function and appropriate range of feedback parameter. Based on this method we use the phase compression method to extend the range of the parameter. So, we integrate the feedback control method with the phase compression method to implement the generalised synchronisation and obtain an exact range of feedback parameter. This technique is simple to implement in practice. Numerical simulations show the effectiveness and the feasibility of the proposed program. (general)

Linear information retrieval method in X-ray grating-based phase contrast imaging and its interchangeability with tomographic reconstruction

Science.gov (United States)

Wu, Z.; Gao, K.; Wang, Z. L.; Shao, Q. G.; Hu, R. F.; Wei, C. X.; Zan, G. B.; Wali, F.; Luo, R. H.; Zhu, P. P.; Tian, Y. C.

2017-06-01

In X-ray grating-based phase contrast imaging, information retrieval is necessary for quantitative research, especially for phase tomography. However, numerous and repetitive processes have to be performed for tomographic reconstruction. In this paper, we report a novel information retrieval method, which enables retrieving phase and absorption information by means of a linear combination of two mutually conjugate images. Thanks to the distributive law of the multiplication as well as the commutative law and associative law of the addition, the information retrieval can be performed after tomographic reconstruction, thus simplifying the information retrieval procedure dramatically. The theoretical model of this method is established in both parallel beam geometry for Talbot interferometer and fan beam geometry for Talbot-Lau interferometer. Numerical experiments are also performed to confirm the feasibility and validity of the proposed method. In addition, we discuss its possibility in cone beam geometry and its advantages compared with other methods. Moreover, this method can also be employed in other differential phase contrast imaging methods, such as diffraction enhanced imaging, non-interferometric imaging, and edge illumination.

Phase retrieval from the magnitude of the Fourier transforms of nonperiodic objects

International Nuclear Information System (INIS)

Miao, J.; Sayre, D.; Chapman, H.N.

1998-01-01

It is suggested that, given the magnitude of Fourier transforms sampled at the Bragg density, the phase problem is underdetermined by a factor of 2 for 1D, 2D, and 3D objects. It is therefore unnecessary to oversample the magnitude of Fourier transforms by 2x in each dimension (i.e., oversampling by 4x for 2D and 8x for 3D) in retrieving the phase of 2D and 3D objects. Our computer phasing experiments accurately retrieved the phase from the magnitude of the Fourier transforms of 2D and 3D complex-valued objects by using positivity constraints on the imaginary part of the objects and loose supports, with the oversampling factor much less than 4 for 2D and 8 for 3D objects. Under the same conditions we also obtained reasonably good reconstructions of 2D and 3D complex-valued objects from the magnitude of their Fourier transforms with added noise and a central stop. copyright 1998 Optical Society of America

Optical image encryption using chaos-based compressed sensing and phase-shifting interference in fractional wavelet domain

Science.gov (United States)

Liu, Qi; Wang, Ying; Wang, Jun; Wang, Qiong-Hua

2018-02-01

In this paper, a novel optical image encryption system combining compressed sensing with phase-shifting interference in fractional wavelet domain is proposed. To improve the encryption efficiency, the volume data of original image are decreased by compressed sensing. Then the compacted image is encoded through double random phase encoding in asymmetric fractional wavelet domain. In the encryption system, three pseudo-random sequences, generated by three-dimensional chaos map, are used as the measurement matrix of compressed sensing and two random-phase masks in the asymmetric fractional wavelet transform. It not only simplifies the keys to storage and transmission, but also enhances our cryptosystem nonlinearity to resist some common attacks. Further, holograms make our cryptosystem be immune to noises and occlusion attacks, which are obtained by two-step-only quadrature phase-shifting interference. And the compression and encryption can be achieved in the final result simultaneously. Numerical experiments have verified the security and validity of the proposed algorithm.

Exergy analysis of an adiabatic compressed air energy storage system using a cascade of phase change materials

International Nuclear Information System (INIS)

Tessier, Michael J.; Floros, Michael C.; Bouzidi, Laziz; Narine, Suresh S.

2016-01-01

Adiabatic compressed air energy storage is an emerging energy storage technology with excellent power and storage capacities. Currently, efficiencies are approximately 70%, in part due to the issue of heat loss during the compression stage. An exergy analysis is presented on a novel adiabatic compressed air energy storage system design utilizing a cascade of PCMs (phase change materials) for waste heat storage and recovery. The melting temperatures and enthalpies of the PCMs were optimized for this system and were shown to be dependent on the number of PCMs, the number of compression stages, and the maximum compression ratio. Efficiencies of storage and recovery using this approach are predicted to be as high as 85%, a 15% increase over current designs which do not incorporate PCMs. - Highlights: • A compressed air energy storage plant using phase change materials is proposed. • Increasing number of phase change materials increases roundtrip exergy efficiency. • A thermodynamic model allows melting points and latent heats required to be predicted.

Isoscalar compression modes in relativistic random phase approximation

International Nuclear Information System (INIS)

Ma, Zhong-yu; Van Giai, Nguyen.; Wandelt, A.; Vretenar, D.; Ring, P.

2001-01-01

Monopole and dipole compression modes in nuclei are analyzed in the framework of a fully consistent relativistic random phase approximation (RRPA), based on effective mean-field Lagrangians with nonlinear meson self-interaction terms. The large effect of Dirac sea states on isoscalar strength distribution functions is illustrated for the monopole mode. The main contribution of Fermi and Dirac sea pair states arises through the exchange of the scalar meson. The effect of vector meson exchange is much smaller. For the monopole mode, RRPA results are compared with constrained relativistic mean-field calculations. A comparison between experimental and calculated energies of isoscalar giant monopole resonances points to a value of 250-270 MeV for the nuclear matter incompressibility. A large discrepancy remains between theoretical predictions and experimental data for the dipole compression mode

Experimental and Numerical Study of Jet Controlled Compression Ignition on Combustion Phasing Control in Diesel Premixed Compression Ignition Systems

OpenAIRE

Qiang Zhang; Wuqiang Long; Jiangping Tian; Yicong Wang; Xiangyu Meng

2014-01-01

In order to directly control the premixed combustion phasing, a Jet Controlled Compression Ignition (JCCI) for diesel premixed compression ignition systems is investigated. Experiments were conducted on a single cylinder natural aspirated diesel engine without EGR at 3000 rpm. Numerical models were validated by load sweep experiments at fixed spark timing. Detailed combustion characteristics were analyzed based on the BMEP of 2.18 bar. The simulation results showed that the high temperature j...

Nonlinear approaches for phase retrieval in the Fresnel region for hard X-ray imaging

International Nuclear Information System (INIS)

Davidoiu, Valentina

2013-01-01

The development of highly coherent X-ray sources offers new possibilities to image biological structures at different scales exploiting the refraction of X-rays. The coherence properties of the third-generation synchrotron radiation sources enables efficient implementations of phase contrast techniques. One of the first measurements of the intensity variations due to phase contrast has been reported in 1995 at the European Synchrotron Radiation Facility (ESRF). Phase imaging coupled to tomography acquisition allows three dimensional imaging with an increased sensitivity compared to absorption CT. This technique is particularly attractive to image samples with low absorption constituents. Phase contrast has many applications, ranging from material science, paleontology, bone research to medicine and biology. Several methods to achieve X-ray phase contrast have been proposed during the last years. In propagation based phase contrast, the measurements are made at different sample-to-detector distances. While the intensity data can be acquired and recorded, the phase information of the signal has to be 'retrieved' from the modulus data only. Phase retrieval is thus an ill-posed nonlinear problem and regularization techniques including a priori knowledge are necessary to obtain stable solutions. Several phase recovery methods have been developed in recent years. These approaches generally formulate the phase retrieval problem as a linear one. Nonlinear treatments have not been much investigated. The main purpose of this work was to propose and evaluate new algorithms, in particularly taking into account the nonlinearity of the direct problem. In the first part of this work, we present a Landweber type nonlinear iterative scheme to solve the propagation based phase retrieval problem. This approach uses the analytic expression of the Frechet derivative of the phase-intensity relationship and of its adjoint, which are presented in detail. We also study the effect of

Two-step phase retrieval algorithm based on the quotient of inner products of phase-shifting interferograms

International Nuclear Information System (INIS)

Niu, Wenhu; Zhong, Liyun; Sun, Peng; Zhang, Wangping; Lu, Xiaoxu

2015-01-01

Based on the quotient of inner products, a simple and rapid algorithm is proposed to retrieve the measured phase from two-frame phase-shifting interferograms with unknown phase shifts. Firstly, we filtered the background of interferograms by a Gaussian high-pass filter. Secondly, we calculated the inner products of the background-filtered interferograms. Thirdly, we extracted the phase shifts by the quotient of the inner products then calculated the measured phase by an arctangent function. Finally, we tested the performance of the proposed algorithm by the simulation calculation and the experimental research for a vortex phase plate. Both the simulation calculation and the experimental result showed that the phase shifts and the measured phase with high accuracy can be obtained by the proposed algorithm rapidly and conveniently. (paper)

Tank waste remediation system retrieval and disposal mission phase 1 financial analysis

International Nuclear Information System (INIS)

Wells, M.W.

1998-01-01

The purpose of the Tank Waste Remediation System (TWRS) Retrieval and Disposal Mission Phase 1 Financial Analysis is to provide a quantitative and qualitative cost and schedule risk analysis of HNF-1946, Tank Waste Remediation System Retrieval and Disposal Mission Initial Updated Baseline (Swita et al. 1998). The Updated Baseline (Section 3.0) is compared to the current TWRS Project Multi-Year Work Plan (MYWP) for fiscal year (FY) 1998 and target budgets for FY 1999 through FY 2011 (Section 4.1). The analysis then evaluates the executability of HNF-1946 (Sections 4.2 through 4.5) and recommends a path forward for risk mitigation (Sections 4.6, 4.7, and 5.0). A sound systems engineering approach was applied to understand and analyze the Phase 1B Retrieval and Disposal mission. Program and Level 1 Logics were decomposed to Level 8 of the Work Breakdown Structure (WBS) where logic was detailed, scope was defined, detail durations and estimates prepared, and resource loaded schedules developed. Technical Basis Review (TBR) packages were prepared which include this information and, in addition, defined the enabling assumptions for each task, and the risks associated with performance. This process is discussed in Section 2.1. Detailed reviews at the subactivity within the Level 1 Logic TBR levels were conducted to provide the recommended solution to the Phase 1B Retrieval and Disposal Mission. Independent cost analysis and risk assessments were performed by members of the Lockheed Martin Hanford Corporation (LMHC) Business Management and Chief Financial Officer organization along with specialists in risk analysis from TRW, Inc. and Lockheed Martin Energy Systems. The process evaluated technical, schedule, and cost risk by category (program specific fixed and variable, integrated program, and programmatic) based on risk certainly from high probability well defined to very low probability that is not bounded or priceable as discussed in Section 2.2. The results have been

Single-intensity-recording optical encryption technique based on phase retrieval algorithm and QR code

Science.gov (United States)

Wang, Zhi-peng; Zhang, Shuai; Liu, Hong-zhao; Qin, Yi

2014-12-01

Based on phase retrieval algorithm and QR code, a new optical encryption technology that only needs to record one intensity distribution is proposed. In this encryption process, firstly, the QR code is generated from the information to be encrypted; and then the generated QR code is placed in the input plane of 4-f system to have a double random phase encryption. For only one intensity distribution in the output plane is recorded as the ciphertext, the encryption process is greatly simplified. In the decryption process, the corresponding QR code is retrieved using phase retrieval algorithm. A priori information about QR code is used as support constraint in the input plane, which helps solve the stagnation problem. The original information can be recovered without distortion by scanning the QR code. The encryption process can be implemented either optically or digitally, and the decryption process uses digital method. In addition, the security of the proposed optical encryption technology is analyzed. Theoretical analysis and computer simulations show that this optical encryption system is invulnerable to various attacks, and suitable for harsh transmission conditions.

Phase retrieval from diffraction data utilizing pre-determined partial information

International Nuclear Information System (INIS)

Kim, S.S.; Marathe, S.; Kim, S.N.; Kang, H.C.; Noh, D.Y.

2007-01-01

We developed a phase retrieval algorithm that utilizes pre-determined partial phase information to overcome insufficient oversampling ratio in diffraction data. Implementing the Fourier modulus projection and the modified support projection manifesting the pre-determined information, a generalized difference map and HIO (Hybrid Input-Output) algorithms are developed. Optical laser diffraction data as well as simulated X-ray diffraction data are used to illustrate the validity of the proposed algorithm, which revealed the strength and the limitations of the algorithm. The proposed algorithm can expand the applicability of the diffraction based image reconstruction

Enhanced deterministic phase retrieval using a partially developed speckle field

DEFF Research Database (Denmark)

Almoro, Percival F.; Waller, Laura; Agour, Mostafa

2012-01-01

A technique for enhanced deterministic phase retrieval using a partially developed speckle field (PDSF) and a spatial light modulator (SLM) is demonstrated experimentally. A smooth test wavefront impinges on a phase diffuser, forming a PDSF that is directed to a 4f setup. Two defocused speckle...... intensity measurements are recorded at the output plane corresponding to axially-propagated representations of the PDSF in the input plane. The speckle intensity measurements are then used in a conventional transport of intensity equation (TIE) to reconstruct directly the test wavefront. The PDSF in our...

Two-phase behavior and compression effects in the PEFC gas diffusion medium

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, Partha P [Los Alamos National Laboratory; Kang, Qinjun [Los Alamos National Laboratory; Schulz, Volker P [APL-LANDAU GMBH; Wang, Chao - Yang [PENN STATE UNIV; Becker, Jurgen [NON LANL; Wiegmann, Andreas [NON LANL

2009-01-01

A key performance limitation in the polymer electrolyte fuel cell (PEFC), manifested in terms of mass transport loss, originates from liquid water transport and resulting flooding phenomena in the constituent components. A key contributor to the mass transport loss is the cathode gas diffusion layer (GDL) due to the blockage of available pore space by liquid water thus rendering hindered oxygen transport to the active reaction sites in the electrode. The GDL, therefore, plays an important role in the overall water management in the PEFC. The underlying pore-morphology and the wetting characteristics have significant influence on the flooding dynamics in the GDL. Another important factor is the role of cell compression on the GDL microstructural change and hence the underlying two-phase behavior. In this article, we present the development of a pore-scale modeling formalism coupled With realistic microstructural delineation and reduced order compression model to study the structure-wettability influence and the effect of compression on two-phase behavior in the PEFC GDL.

Numerical analysis for two-dimensional compressible and two-phase flow fields of air-water in Eulerian grid framework

International Nuclear Information System (INIS)

Park, Chan Wook; Lee, Sung Su

2008-01-01

Two-phase compressible flow fields of air-water are investigated numerically in the fixed Eulerian grid framework. The phase interface is captured via volume fractions of ech phase. A way to model two phase compressible flows as a single phase one is found based on an equivalent equation of states of Tait's type for a multiphase cell. The equivalent single phase field is discretized using the Roe's approximate Riemann solver. Two approaches are tried to suppress the pressure oscillation phenomena at the phase interface, a passive advection of volume fraction and a direct pressure relaxation with the compressible form of volume fraction equation. The direct pressure equalizing method suppresses pressure oscillation successfully and generates sharp discontinuities, transmitting and reflecting acoustic waves naturally at the phase interface. In discretizing the compressible form of volume fraction equation, phase interfaces are geometrically reconstructed to minimize the numerical diffusion of volume fraction and relevant variables. The motion of a projectile in a water-filled tube which is fired by the release of highly pressurized air is simulated presuming the flow field as a two dimensional one, and several design factors affecting the projectile movement are investigated

Hanford tank initiative vehicle/based waste retrieval demonstration report phase II, track 2

International Nuclear Information System (INIS)

Berglin, E.J.

1997-01-01

Using the versatile TracPUMpTm, Environmental Specialties Group, LLC (ES) performed a successful Phase 11 demonstration of a Vehicle- Based Waste Retrieval System (VWRS) for removal of waste material and residual liquid found in the Hanford Underground Storage Tanks (ousts). The purpose of this demonstration was to address issues pertaining to the use of a VWRS in OUSTS. The demonstration also revealed the waste removal capabilities of the TracPumpTm and the most effective techniques and equipment to safely and effectively remove waste simulants. ES successfully addressed the following primary issues: I . Dislodge and convey the waste forms present in the Hanford OUSTS; 2. Access the UST through tank openings as small as twenty-four inches in diameter; 3. Traverse a variety of terrains including slopes, sludges, rocks and hard, slippery surfaces without becoming mired; 4. Dislodge and convey waste within the confinement of the Decontamination Containment Capture Vessel (DCCV) and with minimal personnel exposure; 5. Decontaminate equipment to acceptable limits during retrieval from the UST; 6. Perform any required maintenance within the confinement of the DCCV; and 7. Maintain contaminate levels ''as low as reasonably achievable'' (ALARA) within the DCCV due to its crevice and comer-free design. The following materials were used to simulate the physical characteristics of wastes found in Hanford's OUSTS: (1) Hardpan: a clay-type material that has high shear strength; (2) Saltcake: a fertilizer-based material that has high compressive strength; and (3) Wet Sludge.- a sticky, peanut- butter- like material with low shear strength. Four test beds were constructed of plywood and filled with a different simulant to a depth of eight to ten inches. Three of the test beds were of homogenous simulant material, while the fourth bed consisted of a mixture of all three simulant types

Forced phase-locked states and information retrieval in a two-layer network of oscillatory neurons with directional connectivity

International Nuclear Information System (INIS)

Kazantsev, Victor; Pimashkin, Alexey

2007-01-01

We propose two-layer architecture of associative memory oscillatory network with directional interlayer connectivity. The network is capable to store information in the form of phase-locked (in-phase and antiphase) oscillatory patterns. The first (input) layer takes an input pattern to be recognized and their units are unidirectionally connected with all units of the second (control) layer. The connection strengths are weighted using the Hebbian rule. The output (retrieved) patterns appear as forced-phase locked states of the control layer. The conditions are found and analytically expressed for pattern retrieval in response on incoming stimulus. It is shown that the system is capable to recover patterns with a certain level of distortions or noises in their profiles. The architecture is implemented with the Kuramoto phase model and using synaptically coupled neural oscillators with spikes. It is found that the spiking model is capable to retrieve patterns using the spiking phase that translates memorized patterns into the spiking phase shifts at different time scales

Extended capture range for focus-diverse phase retrieval in segmented aperture systems using geometrical optics.

Science.gov (United States)

Jurling, Alden S; Fienup, James R

2014-03-01

Extending previous work by Thurman on wavefront sensing for segmented-aperture systems, we developed an algorithm for estimating segment tips and tilts from multiple point spread functions in different defocused planes. We also developed methods for overcoming two common modes for stagnation in nonlinear optimization-based phase retrieval algorithms for segmented systems. We showed that when used together, these methods largely solve the capture range problem in focus-diverse phase retrieval for segmented systems with large tips and tilts. Monte Carlo simulations produced a rate of success better than 98% for the combined approach.

An L1-norm phase constraint for half-Fourier compressed sensing in 3D MR imaging.

Science.gov (United States)

Li, Guobin; Hennig, Jürgen; Raithel, Esther; Büchert, Martin; Paul, Dominik; Korvink, Jan G; Zaitsev, Maxim

2015-10-01

In most half-Fourier imaging methods, explicit phase replacement is used. In combination with parallel imaging, or compressed sensing, half-Fourier reconstruction is usually performed in a separate step. The purpose of this paper is to report that integration of half-Fourier reconstruction into iterative reconstruction minimizes reconstruction errors. The L1-norm phase constraint for half-Fourier imaging proposed in this work is compared with the L2-norm variant of the same algorithm, with several typical half-Fourier reconstruction methods. Half-Fourier imaging with the proposed phase constraint can be seamlessly combined with parallel imaging and compressed sensing to achieve high acceleration factors. In simulations and in in-vivo experiments half-Fourier imaging with the proposed L1-norm phase constraint enables superior performance both reconstruction of image details and with regard to robustness against phase estimation errors. The performance and feasibility of half-Fourier imaging with the proposed L1-norm phase constraint is reported. Its seamless combination with parallel imaging and compressed sensing enables use of greater acceleration in 3D MR imaging.

Spatio-temporal phase retrieval in speckle interferometry with Hilbert transform and two-dimensional phase unwrapping

Science.gov (United States)

Li, Xiangyu; Huang, Zhanhua; Zhu, Meng; He, Jin; Zhang, Hao

2014-12-01

Hilbert transform (HT) is widely used in temporal speckle pattern interferometry, but errors from low modulations might propagate and corrupt the calculated phase. A spatio-temporal method for phase retrieval using temporal HT and spatial phase unwrapping is presented. In time domain, the wrapped phase difference between the initial and current states is directly determined by using HT. To avoid the influence of the low modulation intensity, the phase information between the two states is ignored. As a result, the phase unwrapping is shifted from time domain to space domain. A phase unwrapping algorithm based on discrete cosine transform is adopted by taking advantage of the information in adjacent pixels. An experiment is carried out with a Michelson-type interferometer to study the out-of-plane deformation field. High quality whole-field phase distribution maps with different fringe densities are obtained. Under the experimental conditions, the maximum number of fringes resolvable in a 416×416 frame is 30, which indicates a 15λ deformation along the direction of loading.

Characterizing the information content of cloud thermodynamic phase retrievals from the notional PACE OCI shortwave reflectance measurements

Science.gov (United States)

Coddington, O. M.; Vukicevic, T.; Schmidt, K. S.; Platnick, S.

2017-08-01

We rigorously quantify the probability of liquid or ice thermodynamic phase using only shortwave spectral channels specific to the National Aeronautics and Space Administration's Moderate Resolution Imaging Spectroradiometer, Visible Infrared Imaging Radiometer Suite, and the notional future Plankton, Aerosol, Cloud, ocean Ecosystem imager. The results show that two shortwave-infrared channels (2135 and 2250 nm) provide more information on cloud thermodynamic phase than either channel alone; in one case, the probability of ice phase retrieval increases from 65 to 82% by combining 2135 and 2250 nm channels. The analysis is performed with a nonlinear statistical estimation approach, the GEneralized Nonlinear Retrieval Analysis (GENRA). The GENRA technique has previously been used to quantify the retrieval of cloud optical properties from passive shortwave observations, for an assumed thermodynamic phase. Here we present the methodology needed to extend the utility of GENRA to a binary thermodynamic phase space (i.e., liquid or ice). We apply formal information content metrics to quantify our results; two of these (mutual and conditional information) have not previously been used in the field of cloud studies.

Phase transitions during compression and decompression of clots from platelet-poor plasma, platelet-rich plasma and whole blood.

Science.gov (United States)

Liang, Xiaojun; Chernysh, Irina; Purohit, Prashant K; Weisel, John W

2017-09-15

Blood clots are required to stem bleeding and are subject to a variety of stresses, but they can also block blood vessels and cause heart attacks and ischemic strokes. We measured the compressive response of human platelet-poor plasma (PPP) clots, platelet-rich plasma (PRP) clots and whole blood clots and correlated these measurements with confocal and scanning electron microscopy to track changes in clot structure. Stress-strain curves revealed four characteristic regions, for compression-decompression: (1) linear elastic region; (2) upper plateau or softening region; (3) non-linear elastic region or re-stretching of the network; (4) lower plateau in which dissociation of some newly made connections occurs. Our experiments revealed that compression proceeds by the passage of a phase boundary through the clot separating rarefied and densified phases. This observation motivates a model of fibrin mechanics based on the continuum theory of phase transitions, which accounts for the pre-stress caused by platelets, the adhesion of fibrin fibers in the densified phase, the compression of red blood cells (RBCs), and the pumping of liquids through the clot during compression/decompression. Our experiments and theory provide insights into the mechanical behavior of blood clots that could have implications clinically and in the design of fibrin-based biomaterials. The objective of this paper is to measure and mathematically model the compression behavior of various human blood clots. We show by a combination of confocal and scanning electron microscopy that compression proceeds by the passage of a front through the sample that separates a densified region of the clot from a rarefied region, and that the compression/decompression response is reversible with hysteresis. These observations form the basis of a model for the compression response of clots based on the continuum theory of phase transitions. Our studies may reveal how clot rheology under large compression in vivo due

Phase Transitions in Aluminum Under Shockless Compression at the Z Machine

Science.gov (United States)

Davis, Jean-Paul; Brown, Justin; Shulenburger, Luke; Knudson, Marcus

2017-06-01

Aluminum 6061 alloy has been used extensively as an electrode material in shockless ramp-wave experiments at the Z Machine. Previous theoretical work suggests that the principal quasi-isentrope in aluminum should pass through two phase transitions at multi-megabar pressures, first from the ambient fcc phase to hcp at around 200 GPa, then to bcc at around 320 GPa. Previous static measurements in a diamond-anvil cell have detected the hcp phase above 200 GPa along the room-temperature isentherm. Recent laser-based dynamic compression experiments have observed both the hcp and bcc phases using X-ray diffraction. Here we present high-accuracy velocity waveform data taken on pure and alloy aluminum materials at the Z Machine under shockless compression with 200-ns rise-time to 400 GPa using copper electrodes and lithium-fluoride windows. These are compared to recent EOS tables developed at Los Alamos National Laboratory, to our own results from diffusion quantum Monte-Carlo calculations, and to multi-phase EOS models with phase-transition kinetics. We find clear evidence of a fast transition around 200 GPa as expected, and a possible suggestion of a slower transition at higher pressure. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE AC04-94AL85000.

Observation of a New High-Pressure Solid Phase in Dynamically Compressed Aluminum

Science.gov (United States)

Polsin, D. N.

2017-10-01

Aluminum is ideal for testing theoretical first-principles calculations because of the relative simplicity of its atomic structure. Density functional theory (DFT) calculations predict that Al transforms from an ambient-pressure, face-centered-cubic (fcc) crystal to the hexagonal close-packed (hcp) and body-centered-cubic (bcc) structures as it is compressed. Laser-driven experiments performed at the University of Rochester's Laboratory for Laser Energetics and the National Ignition Facility (NIF) ramp compressed Al samples to pressures up to 540 GPa without melting. Nanosecond in-situ x-ray diffraction was used to directly measure the crystal structure at pressures where the solid-solid phase transformations of Al are predicted to occur. Laser velocimetry provided the pressure in the Al. Our results show clear evidence of the fcc-hcp and hpc-bcc transformations at 216 +/- 9 GPa and 321 +/- 12 GPa, respectively. This is the first experimental in-situ observation of the bcc phase in compressed Al and a confirmation of the fcc-hcp transition previously observed under static compression at 217 GPa. The observations indicate these solid-solid phase transitions occur on the order of tens of nanoseconds time scales. In the fcc-hcp transition we find the original texture of the sample is preserved; however, the hcp-bcc transition diminishes that texture producing a structure that is more polycrystalline. The importance of this dynamic is discussed. The NIF results are the first demonstration of x-ray diffraction measurements at two different pressures in a single laser shot. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Feasibility study: Assess the feasibility of siting a monitored retrievable storage facility. Phase 1

Energy Technology Data Exchange (ETDEWEB)

King, J.W.

1993-08-01

The purpose of phase one of this study are: To understand the waste management system and a monitored retrievable storage facility; and to determine whether the applicant has real interest in pursuing the feasibility assessment process. Contents of this report are: Generating electric power; facts about exposure to radiation; handling storage, and transportation techniques; description of a proposed monitored retrievable storage facility; and benefits to be received by host jurisdiction.

Experimental and Numerical Study of Jet Controlled Compression Ignition on Combustion Phasing Control in Diesel Premixed Compression Ignition Systems

Directory of Open Access Journals (Sweden)

Qiang Zhang

2014-07-01

Full Text Available In order to directly control the premixed combustion phasing, a Jet Controlled Compression Ignition (JCCI for diesel premixed compression ignition systems is investigated. Experiments were conducted on a single cylinder natural aspirated diesel engine without EGR at 3000 rpm. Numerical models were validated by load sweep experiments at fixed spark timing. Detailed combustion characteristics were analyzed based on the BMEP of 2.18 bar. The simulation results showed that the high temperature jets of reacting active radical species issued from the ignition chamber played an important role on the onset of combustion in the JCCI system. The combustion of diesel pre-mixtures was initiated rapidly by the combustion products issued from the ignition chamber. Moreover, the flame propagation was not obvious, similar to that in Pre-mixed Charge Compression Ignition (PCCI. Consequently, spark timing sweep experiments were conducted. The results showed a good linear relationship between spark timing in the ignition chamber and CA10 and CA50, which indicated the ability for direct combustion phasing control in diesel PCCI. The NOx and soot emissions gradually changed with the decrease of spark advance angle. The maximum reduction of NOx and soot were both over 90%, and HC and CO emissions were increased.

Novel concepts for the compression of large volumes of carbon dioxide-phase III

Energy Technology Data Exchange (ETDEWEB)

Moore, J. Jeffrey [Southwest Research Inst., San Antonio, TX (United States); Allison, Timothy C. [Southwest Research Inst., San Antonio, TX (United States); Evans, Neal D. [Southwest Research Inst., San Antonio, TX (United States); Moreland, Brian [Southwest Research Inst., San Antonio, TX (United States); Hernandez, Augusto J. [Southwest Research Inst., San Antonio, TX (United States); Day, Meera [Southwest Research Inst., San Antonio, TX (United States); Ridens, Brandon L. [Southwest Research Inst., San Antonio, TX (United States)

2014-06-30

In the effort to reduce the release of CO₂ greenhouse gases to the atmosphere, sequestration of CO₂ from Integrated Gasification Combined Cycle (IGCC) and Oxy-Fuel power plants is being pursued. This approach, however, requires significant compression power to boost the pressure to typical pipeline levels. The penalty can be as high as 8-12% on a typical IGCC plant. The goal of this research is to reduce this penalty through novel compression concepts and integration with existing IGCC processes. The primary objective of the study of novel CO₂ compression concepts is to reliably boost the pressure of CO₂ to pipeline pressures with the minimal amount of energy required. Fundamental thermodynamics were studied to explore pressure rise in both liquid and gaseous states. For gaseous compression, the project investigated novel methods to compress CO₂ while removing the heat of compression internal to the compressor. The highpressure ratio, due to the delivery pressure of the CO₂ for enhanced oil recovery, results in significant heat of compression. Since less energy is required to boost the pressure of a cooler gas stream, both upstream and inter-stage cooling is desirable. While isothermal compression has been utilized in some services, it has not been optimized for the IGCC environment. Phase I of this project determined the optimum compressor configuration and developed technology concepts for internal heat removal. Other compression options using liquefied CO₂ and cryogenic pumping were explored as well. Preliminary analysis indicated up to a 35% reduction in power is possible with the new concepts being considered. In the Phase II program, two experimental test rigs were developed to investigate the two concepts further. A new pump loop facility was constructed to qualify a cryogenic turbopump for use on liquid CO₂ . Also, an internally cooled compressor diaphragm was developed

Comparison of POLDER Cloud Phase Retrievals to Active Remote Sensors Measurements at the ARM SGP Site

International Nuclear Information System (INIS)

Riedi, J.; Goloub, P.; Marchand, Roger T.

2001-01-01

In our present study, cloud boundaries derived from a combination of active remote sensors at the ARM SGP site are compared to POLDER cloud top phase index which is derived from polarimetric measurements using an innovative method. This approach shows the viability of the POLDER phase retrieval algorithm, and also leads to interesting results. In particular, the analysis demonstrates the sensitivity of polarization measurements to ice crystal shape and indicates that occurrence of polycrystalline ice clouds has to be taken into account in order to improve the POLDER phase retrieval algorithm accuracy. Secondly, the results show that a temperature threshold of 240 K could serve for cloud top particle phase classification. Considering the limitations of the analysis, the temperature threshold could be biased high, but not by more than about 5 degrees

Use of phase change materials during compressed air expansion for isothermal CAES plants

Science.gov (United States)

Castellani, B.; Presciutti, A.; Morini, E.; Filipponi, M.; Nicolini, A.; Rossi, F.

2017-11-01

Compressed air energy storage (CAES) plants are designed to store compressed air into a vessel or in an underground cavern and to expand it in an expansion turbine when energy demand is high. An innovative CAES configuration recently proposed is the isothermal process. Several methods to implement isothermal CAES configuration are under investigation. In this framework, the present paper deals with the experimental testing of phase change materials (PCM) during compressed air expansion phase. The experimental investigation was carried out by means of an apparatus constituted by a compression section, a steel pressure vessel, to which an expansion valve is connected. The initial internal absolute pressure was equal to 5 bar to avoid moisture condensation and the experimental tests were carried out with two paraffin-based PCM amounts (0.05 kg and 0.1 kg). Results show that the temperature change during air expansion decreases with increasing the PCM amount inside the vessel. With the use of PCM during expansions an increase of the expansion work occurs. The increase is included in the range from 9.3% to 18.2%. In every test there is an approach to the isothermal values, which represent the maximum theoretical value of the obtainable expansion work.

Phase transition of KCl under shock compression

CERN Document Server

Mashimo, T; Tsumoto, K; Zhang, Y; Ando, S; Tonda, H

2002-01-01

It had been reported that for potassium chloride (KCl) the B1-B2 phase transition (PT) occurs under shock and static compressions, but the measured transition points showed large scatter. In this study, Hugoniot measurement experiments were performed on KCl single crystals by the inclined-mirror method combined with use of a powder gun. The anisotropic Hugoniot elastic limits and PT points were observed. The PT points along the (100), (110) and (111) axis directions were determined as 2.5, 2.2 and 2.1 GPa, respectively. The anisotropic transition was reasonably explained in terms of the displacement mechanism along the (111) axis direction.

Inertia and compressibility effects on density waves and Ledinegg phenomena in two-phase flow systems

International Nuclear Information System (INIS)

Ruspini, L.C.

2012-01-01

Highlights: ► The stability influence of piping fluid inertia on two-phase instabilities is studied. ► Inlet inertia stabilizes the system while outlet inertia destabilizes it. ► High-order modes oscillations are found and analyzed. ► The effect of compressible volumes in the system is studied. ► Inlet compressibility destabilizes the system while outlet comp. stabilizes it. - Abstract: The most common kind of static and dynamic two-phase flow instabilities namely Ledinegg and density wave oscillations are studied. A new model to study two-phase flow instabilities taking into account general parameters from real systems is proposed. The stability influence of external parameters such as the fluid inertia and the presence of compressible gases in the system is analyzed. High-order oscillation modes are found to be related with the fluid inertia of external piping. The occurrence of high-order modes in experimental works is analyzed with focus on the results presented in this work. Moreover, both inertia and compressibility are proven to have a high impact on the stability limits of the systems. The performed study is done by modeling the boiling channel using a one dimensional equilibrium model. An incompressible transient model describes the evolution of the flow and pressure in the non-heated regions and an ideal gas model is used to simulate the compressible volumes in the system. The use of wavelet decomposition analysis is proven to be an efficient tool in stability analysis of several frequencies oscillations.

Numerical simulation of compressible two-phase flow using a diffuse interface method

International Nuclear Information System (INIS)

Ansari, M.R.; Daramizadeh, A.

2013-01-01

Highlights: ► Compressible two-phase gas–gas and gas–liquid flows simulation are conducted. ► Interface conditions contain shock wave and cavitations. ► A high-resolution diffuse interface method is investigated. ► The numerical results exhibit very good agreement with experimental results. -- Abstract: In this article, a high-resolution diffuse interface method is investigated for simulation of compressible two-phase gas–gas and gas–liquid flows, both in the presence of shock wave and in flows with strong rarefaction waves similar to cavitations. A Godunov method and HLLC Riemann solver is used for discretization of the Kapila five-equation model and a modified Schmidt equation of state (EOS) is used to simulate the cavitation regions. This method is applied successfully to some one- and two-dimensional compressible two-phase flows with interface conditions that contain shock wave and cavitations. The numerical results obtained in this attempt exhibit very good agreement with experimental results, as well as previous numerical results presented by other researchers based on other numerical methods. In particular, the algorithm can capture the complex flow features of transient shocks, such as the material discontinuities and interfacial instabilities, without any oscillation and additional diffusion. Numerical examples show that the results of the method presented here compare well with other sophisticated modeling methods like adaptive mesh refinement (AMR) and local mesh refinement (LMR) for one- and two-dimensional problems

Quantization analysis of speckle intensity measurements for phase retrieval

DEFF Research Database (Denmark)

Maallo, Anne Margarette S.; Almoro, Percival F.; Hanson, Steen Grüner

2010-01-01

Speckle intensity measurements utilized for phase retrieval (PR) are sequentially taken with a digital camera, which introduces quantization error that diminishes the signal quality. Influences of quantization on the speckle intensity distribution and PR are investigated numerically...... and experimentally in the static wavefront sensing setup. Resultsshowthat 3 to 4 bits are adequate to represent the speckle intensities and yield acceptable reconstructions at relatively fast convergence rates. Computer memory requirements may be eased down by 2.4 times if a 4 bit instead of an 8 bit camera is used...

Atomistic simulation of fcc—bcc phase transition in single crystal Al under uniform compression

International Nuclear Information System (INIS)

Li Li; Liang Jiu-Qing; Shao Jian-Li; Duan Su-Qing; Li Yan-Fang

2012-01-01

By molecular dynamics simulations employing an embedded atom model potential, we investigate the fcc-to-bcc phase transition in single crystal Al, caused by uniform compression. Results show that the fcc structure is unstable when the pressure is over 250 GPa, in reasonable agreement with the calculated value through the density functional theory. The morphology evolution of the structural transition and the corresponding transition mechanism are analysed in detail. The bcc (011) planes are transited from the fcc (111-bar) plane and the (11-bar1) plane. We suggest that the transition mechanism consists mainly of compression, shear, slid and rotation of the lattice. In addition, our radial distribution function analysis explicitly indicates the phase transition of Al from fcc phase to bcc structure. (condensed matter: structural, mechanical, and thermal properties)

Phase shift extraction and wavefront retrieval from interferograms with background and contrast fluctuations

International Nuclear Information System (INIS)

Liu, Qian; Wang, Yang; He, Jianguo; Ji, Fang

2015-01-01

The fluctuations of background and contrast cause measurement errors in the phase-shifting technique. To extract the phase shifts from interferograms with background and contrast fluctuations, an iterative algorithm is represented. The phase shifts and wavefront phase are calculated in two individual steps with the least-squares method. The fluctuation factors are determined when the phase shifts are calculated, and the fluctuations are compensated when the wavefront phase is calculated. The advantage of the algorithm lies in its ability to extract phase shifts from interferograms with background and contrast fluctuations converging stably and rapidly. Simulations and experiments verify the effectiveness and reliability of the proposed algorithm. The convergence accuracy and speed are demonstrated by the simulation results. The experiment results show its ability for suppressing phase retrieval errors. (paper)

Accelerated Adaptive MGS Phase Retrieval

Science.gov (United States)

Lam, Raymond K.; Ohara, Catherine M.; Green, Joseph J.; Bikkannavar, Siddarayappa A.; Basinger, Scott A.; Redding, David C.; Shi, Fang

2011-01-01

The Modified Gerchberg-Saxton (MGS) algorithm is an image-based wavefront-sensing method that can turn any science instrument focal plane into a wavefront sensor. MGS characterizes optical systems by estimating the wavefront errors in the exit pupil using only intensity images of a star or other point source of light. This innovative implementation of MGS significantly accelerates the MGS phase retrieval algorithm by using stream-processing hardware on conventional graphics cards. Stream processing is a relatively new, yet powerful, paradigm to allow parallel processing of certain applications that apply single instructions to multiple data (SIMD). These stream processors are designed specifically to support large-scale parallel computing on a single graphics chip. Computationally intensive algorithms, such as the Fast Fourier Transform (FFT), are particularly well suited for this computing environment. This high-speed version of MGS exploits commercially available hardware to accomplish the same objective in a fraction of the original time. The exploit involves performing matrix calculations in nVidia graphic cards. The graphical processor unit (GPU) is hardware that is specialized for computationally intensive, highly parallel computation. From the software perspective, a parallel programming model is used, called CUDA, to transparently scale multicore parallelism in hardware. This technology gives computationally intensive applications access to the processing power of the nVidia GPUs through a C/C++ programming interface. The AAMGS (Accelerated Adaptive MGS) software takes advantage of these advanced technologies, to accelerate the optical phase error characterization. With a single PC that contains four nVidia GTX-280 graphic cards, the new implementation can process four images simultaneously to produce a JWST (James Webb Space Telescope) wavefront measurement 60 times faster than the previous code.

Single-image phase retrieval using an edge illumination X-ray phase-contrast imaging setup

Energy Technology Data Exchange (ETDEWEB)

Diemoz, Paul C., E-mail: p.diemoz@ucl.ac.uk; Vittoria, Fabio A. [University College London, London WC1 E6BT (United Kingdom); Research Complex at Harwell, Oxford Harwell Campus, Didcot OX11 0FA (United Kingdom); Hagen, Charlotte K.; Endrizzi, Marco [University College London, London WC1 E6BT (United Kingdom); Coan, Paola [Ludwig-Maximilians-University, Munich 81377 (Germany); Ludwig-Maximilians-University, Garching 85748 (Germany); Brun, Emmanuel [Ludwig-Maximilians-University, Garching 85748 (Germany); European Synchrotron Radiation Facility, Grenoble 38043 (France); Wagner, Ulrich H.; Rau, Christoph [Diamond Light Source, Harwell Oxford Campus, Didcot OX11 0DE (United Kingdom); Robinson, Ian K. [Research Complex at Harwell, Oxford Harwell Campus, Didcot OX11 0FA (United Kingdom); London Centre for Nanotechnology, London WC1 H0AH (United Kingdom); Bravin, Alberto [European Synchrotron Radiation Facility, Grenoble 38043 (France); Olivo, Alessandro [University College London, London WC1 E6BT (United Kingdom); Research Complex at Harwell, Oxford Harwell Campus, Didcot OX11 0FA (United Kingdom)

2015-06-25

A method enabling the retrieval of thickness or projected electron density of a sample from a single input image is derived theoretically and successfully demonstrated on experimental data. A method is proposed which enables the retrieval of the thickness or of the projected electron density of a sample from a single input image acquired with an edge illumination phase-contrast imaging setup. The method assumes the case of a quasi-homogeneous sample, i.e. a sample with a constant ratio between the real and imaginary parts of its complex refractive index. Compared with current methods based on combining two edge illumination images acquired in different configurations of the setup, this new approach presents advantages in terms of simplicity of acquisition procedure and shorter data collection time, which are very important especially for applications such as computed tomography and dynamical imaging. Furthermore, the fact that phase information is directly extracted, instead of its derivative, can enable a simpler image interpretation and be beneficial for subsequent processing such as segmentation. The method is first theoretically derived and its conditions of applicability defined. Quantitative accuracy in the case of homogeneous objects as well as enhanced image quality for the imaging of complex biological samples are demonstrated through experiments at two synchrotron radiation facilities. The large range of applicability, the robustness against noise and the need for only one input image suggest a high potential for investigations in various research subjects.

Compressive and flexural strength of high strength phase change mortar

Science.gov (United States)

Qiao, Qingyao; Fang, Changle

2018-04-01

High-strength cement produces a lot of hydration heat when hydrated, it will usually lead to thermal cracks. Phase change materials (PCM) are very potential thermal storage materials. Utilize PCM can help reduce the hydration heat. Research shows that apply suitable amount of PCM has a significant effect on improving the compressive strength of cement mortar, and can also improve the flexural strength to some extent.

Isoclinic Ambiguity Unwrapping of Circular Ring under Diametric Compression

Directory of Open Access Journals (Sweden)

Huang M.-J.

2010-06-01

Full Text Available Isoclinic and isochromatic parameters in photoelastic analysis are formulated by arc tangent function of several phase shifting frames but for isochromatic calculation it is, in addition, in terms of isoclinic data also. Thus, any isoclinic phase ambiguity would also result in the phase inconsistencies of isochromatic calculation and cause unwrapping problems and difficulties. Many methods had been proposed to treat these kinds of isochromatic fringes but lots of treatments were needed for the correct retrieval. In this work, the isoclinic ambiguity problem is investigated and solved directly by a novel regional phase unwrapping technique. Once the isoclinic phase ambiguity problems are solved, a correct isoclinic result can be obtained. Then, substituting this result into the isochromatic formation yields an ambiguity free isochromatic phase map, which can be easily restored by any phase unwrapping algorithm. A stress frozen sample - circular ring under diametric compression verifies its effectiveness. Usually happened is that this kind of sample is with ambiguous isoclinic data which would cause phase ambiguities of the isochromatic formulation if not treated well first.

An ab initio study on compressibility of Al-containing MAX-phase carbides

International Nuclear Information System (INIS)

Bai, Yuelei; He, Xiaodong; Wang, Rongguo; Zhu, Chuncheng

2013-01-01

The compressibility of Al-containing MAX carbides was investigated in details using first-principle calculations based on density functional theory. The bond stiffness and bond angle as a function of pressure were examined. The M-Al bond stiffness is about 1/3–1/2 of M-C bond stiffness. The M-C bond close to Al atoms has the highest bond stiffness in M 3 AlC 2 and M 4 AlC 3 phases, with the similar bond stiffness of the other two bonds in the latter. Generally, the bond stiffness of the strongest M-C bond increases with increasing VEC (Valence Electron Concentration), which also affects the bond stiffness of other bonds. Of most importance, the bulk moduli are 0.256 of the mean bond stiffness for three series. With increasing pressure, M-Al bond angle increases, but M-C bond angles decreases, which indicates that M-Al and M-C bonds shift towards basal plane and along c-axis, respectively. As a result, the compressibility becomes more difficult along c-axis than a-axis. Some abnormal phenomena in the compressibility of Al-containing M n+1 AlX n phases with VEC = 6 are attributed to the thermodynamical instability of these compounds

Robust retrieval of fine art paintings

Science.gov (United States)

Smolka, Bogdan; Lukac, Rastislav; Plataniotis, Konstantinos N.; Venetsanopoulos, Anastasios N.

2003-10-01

The rapid growth of image archives increases the need for efficient and fast tools that can retrieve and search through large amount of visual data. In this paper we propose an efficient method of extracting the image color content, which serves as an image digital signature, allowing to efficiently index and retrieve the content of large, heterogeneous multimedia databases. We apply the proposed method for the retrieval of images from the WEBMUSEUM Internet database, containing the collection of fine art images and show that the new method of image color representation is robust to image distorsions caused by resizing and compression and can be incorporated into existing retrieval systems which exploit the information on color content in digital images.

Deterministic matrices matching the compressed sensing phase transitions of Gaussian random matrices

OpenAIRE

Monajemi, Hatef; Jafarpour, Sina; Gavish, Matan; Donoho, David L.; Ambikasaran, Sivaram; Bacallado, Sergio; Bharadia, Dinesh; Chen, Yuxin; Choi, Young; Chowdhury, Mainak; Chowdhury, Soham; Damle, Anil; Fithian, Will; Goetz, Georges; Grosenick, Logan

2012-01-01

In compressed sensing, one takes samples of an N-dimensional vector using an matrix A, obtaining undersampled measurements . For random matrices with independent standard Gaussian entries, it is known that, when is k-sparse, there is a precisely determined phase transition: for a certain region in the (,)-phase diagram, convex optimization typically finds the sparsest solution, whereas outside that region, it typically fails. It has been shown empirically that the same property—with the ...

Compressing Control System Data for Efficient Storage and Retrieval

International Nuclear Information System (INIS)

Christopher Larrieu

2003-01-01

The controls group at the Thomas Jefferson National Accelerator Facility (Jefferson Lab), acquires multiple terabytes of EPICS control system data per year via CZAR, its new archiving system. By heuristically applying a combination of rudimentary compression techniques, in conjunction with several specialized data transformations and algorithms, the CZAR storage engine reduces the size of this data by approximately 88 percent, without any loss of information. While the compression process requires significant memory and processor time, the decompression routine suffers only slightly in this regard

Hybrid phase retrieval algorithm for solving the twin image problem in in-line digital holography

Science.gov (United States)

Zhao, Jie; Wang, Dayong; Zhang, Fucai; Wang, Yunxin

2010-10-01

For the reconstruction in the in-line digital holography, there are three terms overlapping with each other on the image plane, named the zero order term, the real image and the twin image respectively. The unwanted twin image degrades the real image seriously. A hybrid phase retrieval algorithm is presented to address this problem, which combines the advantages of two popular phase retrieval algorithms. One is the improved version of the universal iterative algorithm (UIA), called the phase flipping-based UIA (PFB-UIA). The key point of this algorithm is to flip the phase of the object iteratively. It is proved that the PFB-UIA is able to find the support of the complicated object. Another one is the Fienup algorithm, which is a kind of well-developed algorithm and uses the support of the object as the constraint among the iteration procedure. Thus, by following the Fienup algorithm immediately after the PFB-UIA, it is possible to produce the amplitude and the phase distributions of the object with high fidelity. The primary simulated results showed that the proposed algorithm is powerful for solving the twin image problem in the in-line digital holography.

The α-γ-ɛ triple point and phase boundaries of iron under shock compression

Science.gov (United States)

Li, Jun; Wu, Qiang; Xue, Tao; Geng, Huayun; Yu, Jidong; Jin, Ke; Li, Jiabo; Tan, Ye; Xi, Feng

2017-07-01

The phase transition of iron under shock compression has attracted much attention in recent decades because of its importance in fields such as condensed matter physics, geophysics, and metallurgy. At room temperature, the transition of iron from the α-phase (bcc) to the ɛ-phase (hpc) occurs at a stress of 13 GPa. At high temperature, a triple point followed by transformation to the γ-phase (fcc) is expected. However, the details of the high-temperature phase transitions of iron are still under debate. Here, we investigate the phase-transition behavior of polycrystalline iron under compression from room temperature to 820 K. The results show that the shock-induced phase transition is determined unequivocally from the measured three-wave-structure profiles, which clearly consist of an elastic wave, a plastic wave, and a phase-transition wave. The phase transition is temperature-dependent, with an average rate Δσtr/ΔT of -6.91 MPa/K below 700 K and -34.7 MPa/K at higher temperatures. The shock α-ɛ and α-γ phase boundaries intersect at 10.6 ± 0.53 GPa and 763 K, which agrees with the α-ɛ-γ triple point from early shock wave experiments and recent laser-heated diamond-anvil cell resistivity and in situ X-ray diffraction data but disagrees with the shock pressure-temperature phase diagram reported in 2009 by Zaretsky [J. Appl. Phys. 106, 023510 (2009)].

Bonding and compressibility in molecular and polymeric phases of solid CO2

International Nuclear Information System (INIS)

Gracia, L; Marques, M; Beltran, A; Pendas, A Martin; Recio, J M

2004-01-01

We present the results of a theoretical study of the response of molecular CO 2 -I and CO 2 -III, and polymeric CO 2 -V polymorphs to hydrostatic pressure. Total energy calculations and geometry optimizations have been performed under the local density functional approximation combining a pseudopotential and planewave scheme as implemented in the VASP code. Using the atoms in molecules theory, the network of inter- and intra-molecular chemical bonds of the different phases are rigorously characterized in terms of the values of the electron density and the Laplacian at the bond critical points. The chemical graph of a hypothetical orthorhombic structure displays bonding features that are associated with a precursor geometry of polymeric carbon four-fold coordinated phases. In addition, the bulk compressibility is decomposed into atomic and molecular contributions with the aim of providing a better understanding of the reasons that explain the emergence of low compressible polymorphs at high pressures

Solid waste retrieval. Phase 1, Operational basis

International Nuclear Information System (INIS)

Johnson, D.M.

1994-01-01

This Document describes the operational requirements, procedures, and options for execution of the retrieval of the waste containers placed in buried storage in Burial Ground 218W-4C, Trench 04 as TRU waste or suspect TRU waste under the activity levels defining this waste in effect at the time of placement. Trench 04 in Burial Ground 218W-4C is totally dedicated to storage of retrievable TRU waste containers or retrievable suspect TRU waste containers and has not been used for any other purpose

Solid waste retrieval. Phase 1, Operational basis

Energy Technology Data Exchange (ETDEWEB)

Johnson, D.M.

1994-09-30

This Document describes the operational requirements, procedures, and options for execution of the retrieval of the waste containers placed in buried storage in Burial Ground 218W-4C, Trench 04 as TRU waste or suspect TRU waste under the activity levels defining this waste in effect at the time of placement. Trench 04 in Burial Ground 218W-4C is totally dedicated to storage of retrievable TRU waste containers or retrievable suspect TRU waste containers and has not been used for any other purpose.

Compression and decompression of digital seismic waveform data for storage and communication

International Nuclear Information System (INIS)

Bhadauria, Y.S.; Kumar, Vijai

1991-01-01

Two different classes of data compression schemes, namely physical data compression schemes and logical data compression schemes are examined for their use in storage and communication of digital seismic waveform data. In physical data compression schemes, the physical size of the waveform is reduced. One, therefore, gets only a broad picture of the original waveform, when the data are retrieved and the waveform is reconstituted. Coerrelation between original and decompressed waveform varies inversely with the data compresion ratio. In the logical data compression schemes, the data are stored in a logically encoded form. Storage of unnecessary characters like blank space is avoided. On decompression original data are retrieved and compression error is nil. Three algorithms of logical data compression schemes have been developed and studied. These are : 1) optimum formatting schemes, 2) differential bit reduction scheme, and 3) six bit compression scheme. Results of the above three algorithms of logical compression class are compared with those of physical compression schemes reported in literature. It is found that for all types of data, six bit compression scheme gives the highest value of data compression ratio. (author). 6 refs., 8 figs., 1 appendix, 2 tabs

Performance analysis of algorithms for retrieval of magnetic resonance images for interactive teleradiology

Science.gov (United States)

Atkins, M. Stella; Hwang, Robert; Tang, Simon

2001-05-01

We have implemented a prototype system consisting of a Java- based image viewer and a web server extension component for transmitting Magnetic Resonance Images (MRI) to an image viewer, to test the performance of different image retrieval techniques. We used full-resolution images, and images compressed/decompressed using the Set Partitioning in Hierarchical Trees (SPIHT) image compression algorithm. We examined the SPIHT decompression algorithm using both non- progressive and progressive transmission, focusing on the running times of the algorithm, client memory usage and garbage collection. We also compared the Java implementation with a native C++ implementation of the non- progressive SPIHT decompression variant. Our performance measurements showed that for uncompressed image retrieval using a 10Mbps Ethernet, a film of 16 MR images can be retrieved and displayed almost within interactive times. The native C++ code implementation of the client-side decoder is twice as fast as the Java decoder. If the network bandwidth is low, the high communication time for retrieving uncompressed images may be reduced by use of SPIHT-compressed images, although the image quality is then degraded. To provide diagnostic quality images, we also investigated the retrieval of up to 3 images on a MR film at full-resolution, using progressive SPIHT decompression. The Java-based implementation of progressive decompression performed badly, mainly due to the memory requirements for maintaining the image states, and the high cost of execution of the Java garbage collector. Hence, in systems where the bandwidth is high, such as found in a hospital intranet, SPIHT image compression does not provide advantages for image retrieval performance.

Content-based video retrieval by example video clip

Science.gov (United States)

Dimitrova, Nevenka; Abdel-Mottaleb, Mohamed

1997-01-01

This paper presents a novel approach for video retrieval from a large archive of MPEG or Motion JPEG compressed video clips. We introduce a retrieval algorithm that takes a video clip as a query and searches the database for clips with similar contents. Video clips are characterized by a sequence of representative frame signatures, which are constructed from DC coefficients and motion information (`DC+M' signatures). The similarity between two video clips is determined by using their respective signatures. This method facilitates retrieval of clips for the purpose of video editing, broadcast news retrieval, or copyright violation detection.

Graph Compression by BFS

Directory of Open Access Journals (Sweden)

Alberto Apostolico

2009-08-01

Full Text Available The Web Graph is a large-scale graph that does not fit in main memory, so that lossless compression methods have been proposed for it. This paper introduces a compression scheme that combines efficient storage with fast retrieval for the information in a node. The scheme exploits the properties of the Web Graph without assuming an ordering of the URLs, so that it may be applied to more general graphs. Tests on some datasets of use achieve space savings of about 10% over existing methods.

Compressive Strength of Cometary Surfaces Derived from Radar Observations

Science.gov (United States)

ElShafie, A.; Heggy, E.

2014-12-01

Landing on a comet nucleus and probing it, mechanically using harpoons, penetrometers and drills, and electromagnetically using low frequency radar waves is a complex task that will be tackled by the Rosetta mission for Comet 67P/Churyumov-Gerasimenko. The mechanical properties (i.e. density, porosity and compressive strength) and the electrical properties (i.e. the real and imaginary parts of the dielectric constant) of the comet nucleus, constrain both the mechanical and electromagnetic probing capabilities of Rosetta, as well as the choice of landing site, the safety of the landing, and subsurface data interpretation. During landing, the sounding radar data that will be collected by Rosetta's CONSERT experiment can be used to probe the comet's upper regolith layer by assessing its dielectric properties, which are then inverted to retrieve the surface mechanical properties. These observations can help characterize the mechanical properties of the landing site, which will optimize the operation of the anchor system. In this effort, we correlate the mechanical and electrical properties of cometary analogs to each other, and derive an empirical model that can be used to retrieve density, porosity and compressive strength from the dielectric properties of the upper regolith inverted from CONSERT observations during the landing phase. In our approach we consider snow as a viable cometary material analog due to its low density and its porous nature. Therefore, we used the compressive strength and dielectric constant measurements conducted on snow at a temperature of 250 K and a density range of 0.4-0.9 g/cm3 in order to investigate the relation between compressive strength and dielectric constant under cometary-relevant density range. Our results suggest that compressive strength increases linearly as function of the dielectric constant over the observed density range mentioned above. The minimum and maximum compressive strength of 0.5 and 4.5 MPa corresponded to a

Site- and phase-selective x-ray absorption spectroscopy based on phase-retrieval calculation

International Nuclear Information System (INIS)

Kawaguchi, Tomoya; Fukuda, Katsutoshi; Matsubara, Eiichiro

2017-01-01

Understanding the chemical state of a particular element with multiple crystallographic sites and/or phases is essential to unlocking the origin of material properties. To this end, resonant x-ray diffraction spectroscopy (RXDS) achieved through a combination of x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) techniques can allow for the measurement of diffraction anomalous fine structure (DAFS). This is expected to provide a peerless tool for electronic/local structural analyses of materials with complicated structures thanks to its capability to extract spectroscopic information about a given element at each crystallographic site and/or phase. At present, one of the major challenges for the practical application of RXDS is the rigorous determination of resonant terms from observed DAFS, as this requires somehow determining the phase change in the elastic scattering around the absorption edge from the scattering intensity. This is widely known in the field of XRD as the phase problem. The present review describes the basics of this problem, including the relevant background and theory for DAFS and a guide to a newly-developed phase-retrieval method based on the logarithmic dispersion relation that makes it possible to analyze DAFS without suffering from the intrinsic ambiguities of conventional iterative-fitting. Several matters relating to data collection and correction of RXDS are also covered, with a final emphasis on the great potential of powder-sample-based RXDS (P-RXDS) to be used in various applications relevant to practical materials, including antisite-defect-type electrode materials for lithium-ion batteries. (topical review)

Storage and retrieval of large digital images

Science.gov (United States)

Bradley, J.N.

1998-01-20

Image compression and viewing are implemented with (1) a method for performing DWT-based compression on a large digital image with a computer system possessing a two-level system of memory and (2) a method for selectively viewing areas of the image from its compressed representation at multiple resolutions and, if desired, in a client-server environment. The compression of a large digital image I(x,y) is accomplished by first defining a plurality of discrete tile image data subsets T{sub ij}(x,y) that, upon superposition, form the complete set of image data I(x,y). A seamless wavelet-based compression process is effected on I(x,y) that is comprised of successively inputting the tiles T{sub ij}(x,y) in a selected sequence to a DWT routine, and storing the resulting DWT coefficients in a first primary memory. These coefficients are periodically compressed and transferred to a secondary memory to maintain sufficient memory in the primary memory for data processing. The sequence of DWT operations on the tiles T{sub ij}(x,y) effectively calculates a seamless DWT of I(x,y). Data retrieval consists of specifying a resolution and a region of I(x,y) for display. The subset of stored DWT coefficients corresponding to each requested scene is determined and then decompressed for input to an inverse DWT, the output of which forms the image display. The repeated process whereby image views are specified may take the form an interaction with a computer pointing device on an image display from a previous retrieval. 6 figs.

Pressure-induced phase transformation in ZrW2O8 - Compressibility and thermal expansion of the orthorhombic phase

International Nuclear Information System (INIS)

Hu, Z.; Jorgensen, J.D.; Teslic, S.; Short, S.; Argyriou, D.N.

1997-01-01

In situ neutron powder diffraction has been used to show that the application of hydrostatic pressure at room temperature produces a transformation of ZrW 2 O 8 from the cubic to an orthorhombic phase beginning at 2.1 kbar and completed by 3.1 kbar, with a 5% reduction in volume. After release of pressure, the orthorhombic phase is retained at room temperature. Its thermal expansion is negative below room temperature, but is positive above room temperature with a transformation back to the cubic phase at about 390 K. The WO 4 groups are found to play the dominant role in both phase transformations. The volume compressibilities of the cubic and orthorhombic phases are 1.38 x 10 -3 and 1.53 x 10 -3 kbar -1 , respectively. (orig.)

Radiological Image Compression

Science.gov (United States)

Lo, Shih-Chung Benedict

The movement toward digital images in radiology presents the problem of how to conveniently and economically store, retrieve, and transmit the volume of digital images. Basic research into image data compression is necessary in order to move from a film-based department to an efficient digital -based department. Digital data compression technology consists of two types of compression technique: error-free and irreversible. Error -free image compression is desired; however, present techniques can only achieve compression ratio of from 1.5:1 to 3:1, depending upon the image characteristics. Irreversible image compression can achieve a much higher compression ratio; however, the image reconstructed from the compressed data shows some difference from the original image. This dissertation studies both error-free and irreversible image compression techniques. In particular, some modified error-free techniques have been tested and the recommended strategies for various radiological images are discussed. A full-frame bit-allocation irreversible compression technique has been derived. A total of 76 images which include CT head and body, and radiographs digitized to 2048 x 2048, 1024 x 1024, and 512 x 512 have been used to test this algorithm. The normalized mean -square-error (NMSE) on the difference image, defined as the difference between the original and the reconstructed image from a given compression ratio, is used as a global measurement on the quality of the reconstructed image. The NMSE's of total of 380 reconstructed and 380 difference images are measured and the results tabulated. Three complex compression methods are also suggested to compress images with special characteristics. Finally, various parameters which would effect the quality of the reconstructed images are discussed. A proposed hardware compression module is given in the last chapter.

Image encryption using fingerprint as key based on phase retrieval algorithm and public key cryptography

Science.gov (United States)

Zhao, Tieyu; Ran, Qiwen; Yuan, Lin; Chi, Yingying; Ma, Jing

2015-09-01

In this paper, a novel image encryption system with fingerprint used as a secret key is proposed based on the phase retrieval algorithm and RSA public key algorithm. In the system, the encryption keys include the fingerprint and the public key of RSA algorithm, while the decryption keys are the fingerprint and the private key of RSA algorithm. If the users share the fingerprint, then the system will meet the basic agreement of asymmetric cryptography. The system is also applicable for the information authentication. The fingerprint as secret key is used in both the encryption and decryption processes so that the receiver can identify the authenticity of the ciphertext by using the fingerprint in decryption process. Finally, the simulation results show the validity of the encryption scheme and the high robustness against attacks based on the phase retrieval technique.

1D-VAR Retrieval Using Superchannels

Science.gov (United States)

Liu, Xu; Zhou, Daniel; Larar, Allen; Smith, William L.; Schluessel, Peter; Mango, Stephen; SaintGermain, Karen

2008-01-01

Since modern ultra-spectral remote sensors have thousands of channels, it is difficult to include all of them in a 1D-var retrieval system. We will describe a physical inversion algorithm, which includes all available channels for the atmospheric temperature, moisture, cloud, and surface parameter retrievals. Both the forward model and the inversion algorithm compress the channel radiances into super channels. These super channels are obtained by projecting the radiance spectra onto a set of pre-calculated eigenvectors. The forward model provides both super channel properties and jacobian in EOF space directly. For ultra-spectral sensors such as Infrared Atmospheric Sounding Interferometer (IASI) and the NPOESS Airborne Sounder Testbed Interferometer (NAST), a compression ratio of more than 80 can be achieved, leading to a significant reduction in computations involved in an inversion process. Results will be shown applying the algorithm to real IASI and NAST data.

High pressure phase transitions and compressibilities of Er2Zr2O7 and Ho2Zr2O7

Science.gov (United States)

Zhang, F. X.; Lang, M.; Becker, U.; Ewing, R. C.; Lian, J.

2008-01-01

Phase stability and compressibility of rare earth zirconates with the defect-fluorite structure were investigated by in situ synchrotron x-ray diffraction. A sluggish defect-fluorite to a cotunnitelike phase transformation occurred at pressures of ˜22 and ˜30GPa for Er2Zr2O7 and Ho2Zr2O7, respectively. Enhanced compressibility was found for the high pressure phase as a result of increasing cation coordination number and cation-anion bond length.

High Pressure Phase Transitions and Compressibilities of Er2Zr2O7 and Ho2Zr2O7

Energy Technology Data Exchange (ETDEWEB)

Zhang,F.; Lang, M.; Becker, U.; Ewing, R.; Lian, J.

2008-01-01

Phase stability and compressibility of rare earth zirconates with the defect-fluorite structure were investigated by in situ synchrotron x-ray diffraction. A sluggish defect-fluorite to a cotunnitelike phase transformation occurred at pressures of {approx} 22 and {approx} 30 GPa for Er2Zr2O7 and Ho2Zr2O7, respectively. Enhanced compressibility was found for the high pressure phase as a result of increasing cation coordination number and cation-anion bond length.

Conjugate gradient method for phase retrieval based on the Wirtinger derivative.

Science.gov (United States)

Wei, Zhun; Chen, Wen; Qiu, Cheng-Wei; Chen, Xudong

2017-05-01

A conjugate gradient Wirtinger flow (CG-WF) algorithm for phase retrieval is proposed in this paper. It is shown that, compared with recently reported Wirtinger flow and its modified methods, the proposed CG-WF algorithm is able to dramatically accelerate the convergence rate while keeping the dominant computational cost of each iteration unchanged. We numerically illustrate the effectiveness of our method in recovering 1D Gaussian signals and 2D natural color images under both Gaussian and coded diffraction pattern models.

Design and Simulation of a Vapour Compression Refrigeration System Using Phase Change Material

Directory of Open Access Journals (Sweden)

Siddharth Raju

2018-01-01

Full Text Available The paper details the design and simulation of a solar powered vapour compression refrigeration system. The effect of a phase change material, in this case ice, on a vapour compression refrigeration system powered by solar panels is discussed. The battery and solar panels were sized to allow the system to function as an autonomous unit for a minimum of 12 hours. It was concluded that the presence of a phase change material in the refrigeration system caused a considerable increase in both the on and off time of the compressor. The ratio by which the on time increased was greater than the ratio by which the off time was increased. There was a 219% increase in the on time, a 139% increase in the compressor off time and a 3.5% increase in compressor work accompanied by a 5.5% reduction in COP. Thus, under conditions where there is enough load in the system to cause the initial on and off times of the compressor to be comparable, the presence of a phase change material may result in a greater on period than an off period for the compressor.

Hierarchical multiple binary image encryption based on a chaos and phase retrieval algorithm in the Fresnel domain

International Nuclear Information System (INIS)

Wang, Zhipeng; Hou, Chenxia; Lv, Xiaodong; Wang, Hongjuan; Gong, Qiong; Qin, Yi

2016-01-01

Based on the chaos and phase retrieval algorithm, a hierarchical multiple binary image encryption is proposed. In the encryption process, each plaintext is encrypted into a diffraction intensity pattern by two chaos-generated random phase masks (RPMs). Thereafter, the captured diffraction intensity patterns are partially selected by different binary masks and then combined together to form a single intensity pattern. The combined intensity pattern is saved as ciphertext. For decryption, an iterative phase retrieval algorithm is performed, in which a support constraint in the output plane and a median filtering operation are utilized to achieve a rapid convergence rate without a stagnation problem. The proposed scheme has a simple optical setup and large encryption capacity. In particular, it is well suited for constructing a hierarchical security system. The security and robustness of the proposal are also investigated. (letter)

Advanced conceptual design report solid waste retrieval facility, phase I, project W-113

International Nuclear Information System (INIS)

Smith, K.E.

1994-01-01

Project W-113 will provide the equipment and facilities necessary to retrieve suspect transuranic (TRU) waste from Trench 04 of the 218W-4C burial ground. As part of the retrieval process, waste drums will be assayed, overpacked, vented, head-gas sampled, and x-rayed prior to shipment to the Phase V storage facility in preparation for receipt at the Waste Receiving and Processing Facility (WRAP). Advanced Conceptual Design (ACD) studies focused on project items warranting further definition prior to Title I design and areas where the potential for cost savings existed. This ACD Report documents the studies performed during FY93 to optimize the equipment and facilities provided in relation to other SWOC facilities and to provide additional design information for Definitive Design

Phase retrieval problems in X-ray physics. From modeling to efficient algorithms

International Nuclear Information System (INIS)

Homann, Carolin

2015-01-01

In phase retrieval problems that occur in imaging by coherent X-ray diffraction, one tries to reconstruct information about a sample of interest from possibly noisy intensity measurements of the wave field traversing the sample. The mathematical formulation of these problems bases on some assumptions. Usually one of them is that the X-ray wave field is generated by a point source. In order to address this very idealized assumption, it is common to perform a data preprocessing step, the so-called empty beam correction. Within this work, we study the validity of this approach by presenting a quantitative error estimate. Moreover, in order to solve these phase retrieval problems, we want to incorporate a priori knowledge about the structure of the noise and the solution into the reconstruction process. For this reason, the application of a problem adapted iteratively regularized Newton-type method becomes particularly attractive. This method includes the solution of a convex minimization problem in each iteration step. We present a method for solving general optimization problems of this form. Our method is a generalization of a commonly used algorithm which makes it efficiently applicable to a wide class of problems. We also proof convergence results and show the performance of our method by numerical examples.

James Webb Space Telescope Optical Simulation Testbed: Segmented Mirror Phase Retrieval Testing

Science.gov (United States)

Laginja, Iva; Egron, Sylvain; Brady, Greg; Soummer, Remi; Lajoie, Charles-Philippe; Bonnefois, Aurélie; Long, Joseph; Michau, Vincent; Choquet, Elodie; Ferrari, Marc; Leboulleux, Lucie; Mazoyer, Johan; N’Diaye, Mamadou; Perrin, Marshall; Petrone, Peter; Pueyo, Laurent; Sivaramakrishnan, Anand

2018-01-01

The James Webb Space Telescope (JWST) Optical Simulation Testbed (JOST) is a hardware simulator designed to produce JWST-like images. A model of the JWST three mirror anastigmat is realized with three lenses in form of a Cooke Triplet, which provides JWST-like optical quality over a field equivalent to a NIRCam module, and an Iris AO segmented mirror with hexagonal elements is standing in for the JWST segmented primary. This setup successfully produces images extremely similar to NIRCam images from cryotesting in terms of the PSF morphology and sampling relative to the diffraction limit.The testbed is used for staff training of the wavefront sensing and control (WFS&C) team and for independent analysis of WFS&C scenarios of the JWST. Algorithms like geometric phase retrieval (GPR) that may be used in flight and potential upgrades to JWST WFS&C will be explored. We report on the current status of the testbed after alignment, implementation of the segmented mirror, and testing of phase retrieval techniques.This optical bench complements other work at the Makidon laboratory at the Space Telescope Science Institute, including the investigation of coronagraphy for segmented aperture telescopes. Beyond JWST we intend to use JOST for WFS&C studies for future large segmented space telescopes such as LUVOIR.

Logarithmic compression methods for spectral data

Science.gov (United States)

Dunham, Mark E.

2003-01-01

A method is provided for logarithmic compression, transmission, and expansion of spectral data. A log Gabor transformation is made of incoming time series data to output spectral phase and logarithmic magnitude values. The output phase and logarithmic magnitude values are compressed by selecting only magnitude values above a selected threshold and corresponding phase values to transmit compressed phase and logarithmic magnitude values. A reverse log Gabor transformation is then performed on the transmitted phase and logarithmic magnitude values to output transmitted time series data to a user.

Experimental comparison of phase retrieval methods which use intensity distribution at different planes

International Nuclear Information System (INIS)

Shevkunov, I A; Petrov, N V

2014-01-01

Performance of the three phase retrieval methods that use spatial intensity distributions was investigated in dealing with a task of reconstruction of the amplitude characteristics of the test object. These methods differ both by mathematical models and order of iteration execution. The single-beam multiple-intensity reconstruction method showed the best efficiency in terms of quality of reconstruction and time consumption.

Central upwind scheme for a compressible two-phase flow model.

Science.gov (United States)

Ahmed, Munshoor; Saleem, M Rehan; Zia, Saqib; Qamar, Shamsul

2015-01-01

In this article, a compressible two-phase reduced five-equation flow model is numerically investigated. The model is non-conservative and the governing equations consist of two equations describing the conservation of mass, one for overall momentum and one for total energy. The fifth equation is the energy equation for one of the two phases and it includes source term on the right-hand side which represents the energy exchange between two fluids in the form of mechanical and thermodynamical work. For the numerical approximation of the model a high resolution central upwind scheme is implemented. This is a non-oscillatory upwind biased finite volume scheme which does not require a Riemann solver at each time step. Few numerical case studies of two-phase flows are presented. For validation and comparison, the same model is also solved by using kinetic flux-vector splitting (KFVS) and staggered central schemes. It was found that central upwind scheme produces comparable results to the KFVS scheme.

Central upwind scheme for a compressible two-phase flow model.

Directory of Open Access Journals (Sweden)

Munshoor Ahmed

Full Text Available In this article, a compressible two-phase reduced five-equation flow model is numerically investigated. The model is non-conservative and the governing equations consist of two equations describing the conservation of mass, one for overall momentum and one for total energy. The fifth equation is the energy equation for one of the two phases and it includes source term on the right-hand side which represents the energy exchange between two fluids in the form of mechanical and thermodynamical work. For the numerical approximation of the model a high resolution central upwind scheme is implemented. This is a non-oscillatory upwind biased finite volume scheme which does not require a Riemann solver at each time step. Few numerical case studies of two-phase flows are presented. For validation and comparison, the same model is also solved by using kinetic flux-vector splitting (KFVS and staggered central schemes. It was found that central upwind scheme produces comparable results to the KFVS scheme.

Imaging the 3D structure of secondary osteons in human cortical bone using phase-retrieval tomography

Energy Technology Data Exchange (ETDEWEB)

Arhatari, B D; Peele, A G [Department of Physics, La Trobe University, Victoria 3086 (Australia); Cooper, D M L [Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon (Canada); Thomas, C D L; Clement, J G [Melbourne Dental School, University of Melbourne, Victoria 3010 (Australia)

2011-08-21

By applying a phase-retrieval step before carrying out standard filtered back-projection reconstructions in tomographic imaging, we were able to resolve structures with small differences in density within a densely absorbing sample. This phase-retrieval tomography is particularly suited for the three-dimensional segmentation of secondary osteons (roughly cylindrical structures) which are superimposed upon an existing cortical bone structure through the process of turnover known as remodelling. The resulting images make possible the analysis of the secondary osteon structure and the relationship between an osteon and the surrounding tissue. Our observations have revealed many different and complex 3D structures of osteons that could not be studied using previous methods. This work was carried out using a laboratory-based x-ray source, which makes obtaining these sorts of images readily accessible.

Innovative grout/retrieval demonstration final report

International Nuclear Information System (INIS)

Loomis, G.G.; Thompson, D.N.

1995-01-01

This report presents the results of an evaluation of an innovative retrieval technique for buried transuranic waste. Application of this retrieval technique was originally designed for full pit retrieval; however, it applies equally to a hot spot retrieval technology. The technique involves grouting the buried soil waste matrix with a jet grouting procedure, applying an expansive demolition grout to the matrix, and retrieving the debris. The grouted matrix provides an agglomeration of fine soil particles and contaminants resulting in an inherent contamination control during the dusty retrieval process. A full-scale field demonstration of this retrieval technique was performed on a simulated waste pit at the Idaho National Engineering Laboratory. Details are reported on all phases of this proof-of-concept demonstration including pit construction, jet grouting activities, application of the demolition grout, and actual retrieval of the grouted pit. A quantitative evaluation of aerosolized soils and rare earth tracer spread is given for all phases of the demonstration, and these results are compared to a baseline retrieval activity using conventional retrieval means. 8 refs., 47 figs., 10 tabs

Method for utilizing properties of the sinc(x) function for phase retrieval on nyquist-under-sampled data

Science.gov (United States)

Dean, Bruce H. (Inventor); Smith, Jeffrey Scott (Inventor); Aronstein, David L. (Inventor)

2012-01-01

Disclosed herein are systems, methods, and non-transitory computer-readable storage media for simulating propagation of an electromagnetic field, performing phase retrieval, or sampling a band-limited function. A system practicing the method generates transformed data using a discrete Fourier transform which samples a band-limited function f(x) without interpolating or modifying received data associated with the function f(x), wherein an interval between repeated copies in a periodic extension of the function f(x) obtained from the discrete Fourier transform is associated with a sampling ratio Q, defined as a ratio of a sampling frequency to a band-limited frequency, and wherein Q is assigned a value between 1 and 2 such that substantially no aliasing occurs in the transformed data, and retrieves a phase in the received data based on the transformed data, wherein the phase is used as feedback to an optical system.

Phase retrieval from the phase-shift moiré fringe patterns in simultaneous dual-wavelength interferometry

Science.gov (United States)

Cheng, Jinlong; Gao, Zhishan; Bie, Shuyou; Dou, Yimeng; Ni, Ruihu; Yuan, Qun

2018-02-01

Simultaneous dual-wavelength interferometry (SDWI) could extend the measured range of each single-wavelength interferometry. The moiré fringe generated in SDWI indirectly represents the information of the measured long synthetic-wavelength ({λ }{{S}}) phase, thus the phase demodulation is rather arduous. To address this issue, we present a method to convert the moiré fringe pattern into a synthetic-wavelength interferogram (moiré to synthetic-wavelength, MTS). After the square of the moiré fringe pattern in the MTS method, the additive moiré pattern is turned into a multiplicative one. And the synthetic-wavelength interferogram could be obtained by a low-pass filtering in spectrum of the multiplicative moiré fringe pattern. Therefore, when the dual-wavelength interferometer is implemented with the π/2 phase shift at {λ }{{S}}, a sequence of synthetic-wavelength phase-shift interferograms with π/2 phase shift could be obtained after the MTS method processing on the captured moiré fringe patterns. And then the synthetic-wavelength phase could be retrieved by the conventional phase-shift algorithm. Compared with other methods in SDWI, the proposed MTS approach could reduce the restriction of the phase shift and frame numbers for the adoption of the conventional phase-shift algorithm. Following, numerical simulations are executed to evaluate the performance of the MTS method in processing time, frames of interferograms and the phase shift error compensation. And the necessary linear carrier for MTS method is less than 0.11 times of the traditional dual-wavelength spatial-domain Fourier transform method. Finally, the deviations for MTS method in experiment are 0.97% for a step with the height of 7.8 μm and 1.11% for a Fresnel lens with the step height of 6.2328 μm.

Spatial-area selective retrieval of multiple object-place associations in a hierarchical cognitive map formed by theta phase coding.

Science.gov (United States)

Sato, Naoyuki; Yamaguchi, Yoko

2009-06-01

The human cognitive map is known to be hierarchically organized consisting of a set of perceptually clustered landmarks. Patient studies have demonstrated that these cognitive maps are maintained by the hippocampus, while the neural dynamics are still poorly understood. The authors have shown that the neural dynamic "theta phase precession" observed in the rodent hippocampus may be capable of forming hierarchical cognitive maps in humans. In the model, a visual input sequence consisting of object and scene features in the central and peripheral visual fields, respectively, results in the formation of a hierarchical cognitive map for object-place associations. Surprisingly, it is possible for such a complex memory structure to be formed in a few seconds. In this paper, we evaluate the memory retrieval of object-place associations in the hierarchical network formed by theta phase precession. The results show that multiple object-place associations can be retrieved with the initial cue of a scene input. Importantly, according to the wide-to-narrow unidirectional connections among scene units, the spatial area for object-place retrieval can be controlled by the spatial area of the initial cue input. These results indicate that the hierarchical cognitive maps have computational advantages on a spatial-area selective retrieval of multiple object-place associations. Theta phase precession dynamics is suggested as a fundamental neural mechanism of the human cognitive map.

Batching alternatives for Phase I retrieval wastes to be processed in WRAP Module 1

International Nuclear Information System (INIS)

Mayancsik, B.A.

1994-01-01

During the next two decades, the transuranic (TRU) waste now stored in the 200 Area burial trenches and storage buildings is to be retrieved, processed in the Waste Receiving and Processing (WRAP) Module 1 facility, and shipped to a final disposal facility. The purpose of this document is to identify the criteria that can be used to batch suspect TRU waste, currently in retrievable storage, for processing through the WRAP Module 1 facility. These criteria are then used to generate a batch plan for Phase 1 Retrieval operations, which will retrieve the waste located in Trench 4C-04 of the 200 West Area burial ground. The reasons for batching wastes for processing in WRAP Module 1 include reducing the exposure of workers and the environment to hazardous material and ionizing radiation; maximizing the efficiency of the retrieval, processing, and disposal processes by reducing costs, time, and space throughout the process; reducing analytical sampling and analysis; and reducing the amount of cleanup and decontamination between process runs. The criteria selected for batching the drums of retrieved waste entering WRAP Module 1 are based on the available records for the wastes sent to storage as well as knowledge of the processes that generated these wastes. The batching criteria identified in this document include the following: waste generator; type of process used to generate or package the waste; physical waste form; content of hazardous/dangerous chemicals in the waste; radiochemical type and quantity of waste; drum weight; and special waste types. These criteria were applied to the waste drums currently stored in Trench 4C-04. At least one batching scheme is shown for each of the criteria listed above

Integrating uncertainty propagation in GNSS radio occultation retrieval: from excess phase to atmospheric bending angle profiles

Science.gov (United States)

Schwarz, Jakob; Kirchengast, Gottfried; Schwaerz, Marc

2018-05-01

Global Navigation Satellite System (GNSS) radio occultation (RO) observations are highly accurate, long-term stable data sets and are globally available as a continuous record from 2001. Essential climate variables for the thermodynamic state of the free atmosphere - such as pressure, temperature, and tropospheric water vapor profiles (involving background information) - can be derived from these records, which therefore have the potential to serve as climate benchmark data. However, to exploit this potential, atmospheric profile retrievals need to be very accurate and the remaining uncertainties quantified and traced throughout the retrieval chain from raw observations to essential climate variables. The new Reference Occultation Processing System (rOPS) at the Wegener Center aims to deliver such an accurate RO retrieval chain with integrated uncertainty propagation. Here we introduce and demonstrate the algorithms implemented in the rOPS for uncertainty propagation from excess phase to atmospheric bending angle profiles, for estimated systematic and random uncertainties, including vertical error correlations and resolution estimates. We estimated systematic uncertainty profiles with the same operators as used for the basic state profiles retrieval. The random uncertainty is traced through covariance propagation and validated using Monte Carlo ensemble methods. The algorithm performance is demonstrated using test day ensembles of simulated data as well as real RO event data from the satellite missions CHAllenging Minisatellite Payload (CHAMP); Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC); and Meteorological Operational Satellite A (MetOp). The results of the Monte Carlo validation show that our covariance propagation delivers correct uncertainty quantification from excess phase to bending angle profiles. The results from the real RO event ensembles demonstrate that the new uncertainty estimation chain performs robustly. Together

Optimization of multi-phase compressible lattice Boltzmann codes on massively parallel multi-core systems

NARCIS (Netherlands)

Biferale, L.; Mantovani, F.; Pivanti, M.; Pozzati, F.; Sbragaglia, M.; Schifano, S.F.; Toschi, F.; Tripiccione, R.

2011-01-01

We develop a Lattice Boltzmann code for computational fluid-dynamics and optimize it for massively parallel systems based on multi-core processors. Our code describes 2D multi-phase compressible flows. We analyze the performance bottlenecks that we find as we gradually expose a larger fraction of

Age-Related Reversals in Neural Recruitment across Memory Retrieval Phases.

Science.gov (United States)

Ford, Jaclyn H; Kensinger, Elizabeth A

2017-05-17

Over the last several decades, neuroimaging research has identified age-related neural changes that occur during cognitive tasks. These changes are used to help researchers identify functional changes that contribute to age-related impairments in cognitive performance. One commonly reported example of such a change is an age-related decrease in the recruitment of posterior sensory regions coupled with an increased recruitment of prefrontal regions across multiple cognitive tasks. This shift is often described as a compensatory recruitment of prefrontal regions due to age-related sensory-processing deficits in posterior regions. However, age is not only associated with spatial shifts in recruitment, but also with temporal shifts, in which younger and older adults recruit the same neural region at different points in a task trial. The current study examines the possible contribution of temporal modifications in the often-reported posterior-anterior shift. Participants, ages 19-85, took part in a memory retrieval task with a protracted retrieval trial consisting of an initial memory search phase and a subsequent detail elaboration phase. Age-related neural patterns during search replicated prior reports of age-related decreases in posterior recruitment and increases in prefrontal recruitment. However, during the later elaboration phase, the same posterior regions were associated with age-related increases in activation. Further, ROI and functional connectivity results suggest that these posterior regions function similarly during search and elaboration. These results suggest that the often-reported posterior-anterior shift may not reflect the inability of older adults to engage in sensory processing, but rather a change in when they recruit this processing. SIGNIFICANCE STATEMENT The current study provides evidence that the often-reported posterior-anterior shift in aging may not reflect a global sensory-processing deficit, as has often been reported, but rather a

Theoretical extension and experimental demonstration of spectral compression in second-harmonic generation by Fresnel-inspired binary phase shaping

Science.gov (United States)

Li, Baihong; Dong, Ruifang; Zhou, Conghua; Xiang, Xiao; Li, Yongfang; Zhang, Shougang

2018-05-01

Selective two-photon microscopy and high-precision nonlinear spectroscopy rely on efficient spectral compression at the desired frequency. Previously, a Fresnel-inspired binary phase shaping (FIBPS) method was theoretically proposed for spectral compression of two-photon absorption and second-harmonic generation (SHG) with a square-chirped pulse. Here, we theoretically show that the FIBPS can introduce a negative quadratic frequency phase (negative chirp) by analogy with the spatial-domain phase function of Fresnel zone plate. Thus, the previous theoretical model can be extended to the case where the pulse can be transformed limited and in any symmetrical spectral shape. As an example, we experimentally demonstrate spectral compression in SHG by FIBPS for a Gaussian transform-limited pulse and show good agreement with the theory. Given the fundamental pulse bandwidth, a narrower SHG bandwidth with relatively high intensity can be obtained by simply increasing the number of binary phases. The experimental results also verify that our method is superior to that proposed in [Phys. Rev. A 46, 2749 (1992), 10.1103/PhysRevA.46.2749]. This method will significantly facilitate the applications of selective two-photon microscopy and spectroscopy. Moreover, as it can introduce negative dispersion, hence it can also be generalized to other applications in the field of dispersion compensation.

Accelerated radial Fourier-velocity encoding using compressed sensing

Energy Technology Data Exchange (ETDEWEB)

Hilbert, Fabian; Han, Dietbert [Wuerzburg Univ. (Germany). Inst. of Radiology; Wech, Tobias; Koestler, Herbert [Wuerzburg Univ. (Germany). Inst. of Radiology; Wuerzburg Univ. (Germany). Comprehensive Heart Failure Center (CHFC)

2014-10-01

Purpose:Phase Contrast Magnetic Resonance Imaging (MRI) is a tool for non-invasive determination of flow velocities inside blood vessels. Because Phase Contrast MRI only measures a single mean velocity per voxel, it is only applicable to vessels significantly larger than the voxel size. In contrast, Fourier Velocity Encoding measures the entire velocity distribution inside a voxel, but requires a much longer acquisition time. For accurate diagnosis of stenosis in vessels on the scale of spatial resolution, it is important to know the velocity distribution of a voxel. Our aim was to determine velocity distributions with accelerated Fourier Velocity Encoding in an acquisition time required for a conventional Phase Contrast image. Materials and Methods:We imaged the femoral artery of healthy volunteers with ECG - triggered, radial CINE acquisition. Data acquisition was accelerated by undersampling, while missing data were reconstructed by Compressed Sensing. Velocity spectra of the vessel were evaluated by high resolution Phase Contrast images and compared to spectra from fully sampled and undersampled Fourier Velocity Encoding. By means of undersampling, it was possible to reduce the scan time for Fourier Velocity Encoding to the duration required for a conventional Phase Contrast image. Results:Acquisition time for a fully sampled data set with 12 different Velocity Encodings was 40 min. By applying a 12.6 - fold retrospective undersampling, a data set was generated equal to 3:10 min acquisition time, which is similar to a conventional Phase Contrast measurement. Velocity spectra from fully sampled and undersampled Fourier Velocity Encoded images are in good agreement and show the same maximum velocities as compared to velocity maps from Phase Contrast measurements. Conclusion: Compressed Sensing proved to reliably reconstruct Fourier Velocity Encoded data. Our results indicate that Fourier Velocity Encoding allows an accurate determination of the velocity

Accelerated radial Fourier-velocity encoding using compressed sensing

International Nuclear Information System (INIS)

Hilbert, Fabian; Han, Dietbert

2014-01-01

Purpose:Phase Contrast Magnetic Resonance Imaging (MRI) is a tool for non-invasive determination of flow velocities inside blood vessels. Because Phase Contrast MRI only measures a single mean velocity per voxel, it is only applicable to vessels significantly larger than the voxel size. In contrast, Fourier Velocity Encoding measures the entire velocity distribution inside a voxel, but requires a much longer acquisition time. For accurate diagnosis of stenosis in vessels on the scale of spatial resolution, it is important to know the velocity distribution of a voxel. Our aim was to determine velocity distributions with accelerated Fourier Velocity Encoding in an acquisition time required for a conventional Phase Contrast image. Materials and Methods:We imaged the femoral artery of healthy volunteers with ECG - triggered, radial CINE acquisition. Data acquisition was accelerated by undersampling, while missing data were reconstructed by Compressed Sensing. Velocity spectra of the vessel were evaluated by high resolution Phase Contrast images and compared to spectra from fully sampled and undersampled Fourier Velocity Encoding. By means of undersampling, it was possible to reduce the scan time for Fourier Velocity Encoding to the duration required for a conventional Phase Contrast image. Results:Acquisition time for a fully sampled data set with 12 different Velocity Encodings was 40 min. By applying a 12.6 - fold retrospective undersampling, a data set was generated equal to 3:10 min acquisition time, which is similar to a conventional Phase Contrast measurement. Velocity spectra from fully sampled and undersampled Fourier Velocity Encoded images are in good agreement and show the same maximum velocities as compared to velocity maps from Phase Contrast measurements. Conclusion: Compressed Sensing proved to reliably reconstruct Fourier Velocity Encoded data. Our results indicate that Fourier Velocity Encoding allows an accurate determination of the velocity

Accelerated radial Fourier-velocity encoding using compressed sensing.

Science.gov (United States)

Hilbert, Fabian; Wech, Tobias; Hahn, Dietbert; Köstler, Herbert

2014-09-01

Phase Contrast Magnetic Resonance Imaging (MRI) is a tool for non-invasive determination of flow velocities inside blood vessels. Because Phase Contrast MRI only measures a single mean velocity per voxel, it is only applicable to vessels significantly larger than the voxel size. In contrast, Fourier Velocity Encoding measures the entire velocity distribution inside a voxel, but requires a much longer acquisition time. For accurate diagnosis of stenosis in vessels on the scale of spatial resolution, it is important to know the velocity distribution of a voxel. Our aim was to determine velocity distributions with accelerated Fourier Velocity Encoding in an acquisition time required for a conventional Phase Contrast image. We imaged the femoral artery of healthy volunteers with ECG-triggered, radial CINE acquisition. Data acquisition was accelerated by undersampling, while missing data were reconstructed by Compressed Sensing. Velocity spectra of the vessel were evaluated by high resolution Phase Contrast images and compared to spectra from fully sampled and undersampled Fourier Velocity Encoding. By means of undersampling, it was possible to reduce the scan time for Fourier Velocity Encoding to the duration required for a conventional Phase Contrast image. Acquisition time for a fully sampled data set with 12 different Velocity Encodings was 40 min. By applying a 12.6-fold retrospective undersampling, a data set was generated equal to 3:10 min acquisition time, which is similar to a conventional Phase Contrast measurement. Velocity spectra from fully sampled and undersampled Fourier Velocity Encoded images are in good agreement and show the same maximum velocities as compared to velocity maps from Phase Contrast measurements. Compressed Sensing proved to reliably reconstruct Fourier Velocity Encoded data. Our results indicate that Fourier Velocity Encoding allows an accurate determination of the velocity distribution in vessels in the order of the voxel size. Thus

Document retrieval on repetitive string collections.

Science.gov (United States)

Gagie, Travis; Hartikainen, Aleksi; Karhu, Kalle; Kärkkäinen, Juha; Navarro, Gonzalo; Puglisi, Simon J; Sirén, Jouni

2017-01-01

Most of the fastest-growing string collections today are repetitive, that is, most of the constituent documents are similar to many others. As these collections keep growing, a key approach to handling them is to exploit their repetitiveness, which can reduce their space usage by orders of magnitude. We study the problem of indexing repetitive string collections in order to perform efficient document retrieval operations on them. Document retrieval problems are routinely solved by search engines on large natural language collections, but the techniques are less developed on generic string collections. The case of repetitive string collections is even less understood, and there are very few existing solutions. We develop two novel ideas, interleaved LCPs and precomputed document lists , that yield highly compressed indexes solving the problem of document listing (find all the documents where a string appears), top- k document retrieval (find the k documents where a string appears most often), and document counting (count the number of documents where a string appears). We also show that a classical data structure supporting the latter query becomes highly compressible on repetitive data. Finally, we show how the tools we developed can be combined to solve ranked conjunctive and disjunctive multi-term queries under the simple [Formula: see text] model of relevance. We thoroughly evaluate the resulting techniques in various real-life repetitiveness scenarios, and recommend the best choices for each case.

Diffuse-Interface Capturing Methods for Compressible Two-Phase Flows

Science.gov (United States)

Saurel, Richard; Pantano, Carlos

2018-01-01

Simulation of compressible flows became a routine activity with the appearance of shock-/contact-capturing methods. These methods can determine all waves, particularly discontinuous ones. However, additional difficulties may appear in two-phase and multimaterial flows due to the abrupt variation of thermodynamic properties across the interfacial region, with discontinuous thermodynamical representations at the interfaces. To overcome this difficulty, researchers have developed augmented systems of governing equations to extend the capturing strategy. These extended systems, reviewed here, are termed diffuse-interface models, because they are designed to compute flow variables correctly in numerically diffused zones surrounding interfaces. In particular, they facilitate coupling the dynamics on both sides of the (diffuse) interfaces and tend to the proper pure fluid-governing equations far from the interfaces. This strategy has become efficient for contact interfaces separating fluids that are governed by different equations of state, in the presence or absence of capillary effects, and with phase change. More sophisticated materials than fluids (e.g., elastic-plastic materials) have been considered as well.

Determining the phase diagram of lithium via ab initio calculation and ramp compression

Science.gov (United States)

Shulenburger, Luke; Seagle, Chris; Haill, Thomas; Harding, Eric

2015-06-01

Diamond anvil cell experiments have shown elemental lithium to have an extraordinarily complex phase diagram under pressure exhibiting numerous solid phases at pressures below 1 Mbar, as well as a complicated melting behavior. We explore this phase diagram utilizing a combination of quantum mechanical calculations and ramp compression experiments performed on Sandia National Laboratories' Z-machine. We aim to extend our knowledge of the high pressure behavior to moderate temperatures at pressures above 50 GPa with a specific focus on the melt line above 70 GPa. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the US Dept of Energy's Natl. Nuclear Security Administration under Contract DE-AC04-94AL85000.

Deterministic matrices matching the compressed sensing phase transitions of Gaussian random matrices

Science.gov (United States)

Monajemi, Hatef; Jafarpour, Sina; Gavish, Matan; Donoho, David L.; Ambikasaran, Sivaram; Bacallado, Sergio; Bharadia, Dinesh; Chen, Yuxin; Choi, Young; Chowdhury, Mainak; Chowdhury, Soham; Damle, Anil; Fithian, Will; Goetz, Georges; Grosenick, Logan; Gross, Sam; Hills, Gage; Hornstein, Michael; Lakkam, Milinda; Lee, Jason; Li, Jian; Liu, Linxi; Sing-Long, Carlos; Marx, Mike; Mittal, Akshay; Monajemi, Hatef; No, Albert; Omrani, Reza; Pekelis, Leonid; Qin, Junjie; Raines, Kevin; Ryu, Ernest; Saxe, Andrew; Shi, Dai; Siilats, Keith; Strauss, David; Tang, Gary; Wang, Chaojun; Zhou, Zoey; Zhu, Zhen

2013-01-01

In compressed sensing, one takes samples of an N-dimensional vector using an matrix A, obtaining undersampled measurements . For random matrices with independent standard Gaussian entries, it is known that, when is k-sparse, there is a precisely determined phase transition: for a certain region in the (,)-phase diagram, convex optimization typically finds the sparsest solution, whereas outside that region, it typically fails. It has been shown empirically that the same property—with the same phase transition location—holds for a wide range of non-Gaussian random matrix ensembles. We report extensive experiments showing that the Gaussian phase transition also describes numerous deterministic matrices, including Spikes and Sines, Spikes and Noiselets, Paley Frames, Delsarte-Goethals Frames, Chirp Sensing Matrices, and Grassmannian Frames. Namely, for each of these deterministic matrices in turn, for a typical k-sparse object, we observe that convex optimization is successful over a region of the phase diagram that coincides with the region known for Gaussian random matrices. Our experiments considered coefficients constrained to for four different sets , and the results establish our finding for each of the four associated phase transitions. PMID:23277588

A humming retrieval system based on music fingerprint

Science.gov (United States)

Han, Xingkai; Cao, Baiyu

2011-10-01

In this paper, we proposed an improved music information retrieval method utilizing the music fingerprint. The goal of this method is to represent the music with compressed musical information. Based on the selected MIDI files, which are generated automatically as our music target database, we evaluate the accuracy, effectiveness, and efficiency of this method. In this research we not only extract the feature sequence, which can represent the file effectively, from the query and melody database, but also make it possible for retrieving the results in an innovative way. We investigate on the influence of noise to the performance of our system. As experimental result shows, the retrieval accuracy arriving at up to91% without noise is pretty well

Random projections and the optimization of an algorithm for phase retrieval

International Nuclear Information System (INIS)

Elser, Veit

2003-01-01

Iterative phase retrieval algorithms typically employ projections onto constraint subspaces to recover the unknown phases in the Fourier transform of an image, or, in the case of x-ray crystallography, the electron density of a molecule. For a general class of algorithms, where the basic iteration is specified by the difference map, solutions are associated with fixed points of the map, the attractive character of which determines the effectiveness of the algorithm. The behaviour of the difference map near fixed points is controlled by the relative orientation of the tangent spaces of the two constraint subspaces employed by the map. Since the dimensionalities involved are always large in practical applications, it is appropriate to use random matrix theory ideas to analyse the average-case convergence at fixed points. Optimal values of the γ parameters of the difference map are found which differ somewhat from the values previously obtained on the assumption of orthogonal tangent spaces

Intelligent transportation systems data compression using wavelet decomposition technique.

Science.gov (United States)

2009-12-01

Intelligent Transportation Systems (ITS) generates massive amounts of traffic data, which posts : challenges for data storage, transmission and retrieval. Data compression and reconstruction technique plays an : important role in ITS data procession....

Integrating uncertainty propagation in GNSS radio occultation retrieval: from excess phase to atmospheric bending angle profiles

Directory of Open Access Journals (Sweden)

J. Schwarz

2018-05-01

Full Text Available Global Navigation Satellite System (GNSS radio occultation (RO observations are highly accurate, long-term stable data sets and are globally available as a continuous record from 2001. Essential climate variables for the thermodynamic state of the free atmosphere – such as pressure, temperature, and tropospheric water vapor profiles (involving background information – can be derived from these records, which therefore have the potential to serve as climate benchmark data. However, to exploit this potential, atmospheric profile retrievals need to be very accurate and the remaining uncertainties quantified and traced throughout the retrieval chain from raw observations to essential climate variables. The new Reference Occultation Processing System (rOPS at the Wegener Center aims to deliver such an accurate RO retrieval chain with integrated uncertainty propagation. Here we introduce and demonstrate the algorithms implemented in the rOPS for uncertainty propagation from excess phase to atmospheric bending angle profiles, for estimated systematic and random uncertainties, including vertical error correlations and resolution estimates. We estimated systematic uncertainty profiles with the same operators as used for the basic state profiles retrieval. The random uncertainty is traced through covariance propagation and validated using Monte Carlo ensemble methods. The algorithm performance is demonstrated using test day ensembles of simulated data as well as real RO event data from the satellite missions CHAllenging Minisatellite Payload (CHAMP; Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC; and Meteorological Operational Satellite A (MetOp. The results of the Monte Carlo validation show that our covariance propagation delivers correct uncertainty quantification from excess phase to bending angle profiles. The results from the real RO event ensembles demonstrate that the new uncertainty estimation chain performs

Waste retrieval sluicing system vapor sampling and analysis plan for evaluation of organic emissions, process test phase III

International Nuclear Information System (INIS)

SASAKI, L.M.

1999-01-01

This sampling and analysis plan identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for vapor samples obtained to address vapor issues related to the sluicing of tank 241-C-106. Sampling will be performed in accordance with Waste Retrieval Sluicing System Emissions Collection Phase III (Jones 1999) and Process Test Plan Phase III, Waste Retrieval Sluicing System Emissions Collection (Powers 1999). Analytical requirements include those specified in Request for Ecology Concurrence on Draft Strategy/Path Forward to Address Concerns Regarding Organic Emissions from C-106 Sluicing Activities (Peterson 1998). The Waste Retrieval Sluicing System was installed to retrieve and transfer high-heat sludge from tank 241-C-106 to tank 241-AY-102, which is designed for high-heat waste storage. During initial sluicing of tank 241-C-106 in November 1998, operations were halted due to detection of unexpected high volatile organic compounds in emissions that exceeded regulatory permit limits. Several workers also reported smelling sharp odors and throat irritation. Vapor grab samples from the 296-C-006 ventilation system were taken as soon as possible after detection; the analyses indicated that volatile and semi-volatile organic compounds were present. In December 1998, a process test (phase I) was conducted in which the pumps in tanks 241-C-106 and 241-AY-102 were operated and vapor samples obtained to determine constituents that may be present during active sluicing of tank 241-C-106. The process test was suspended when a jumper leak was detected. On March 7, 1999, phase I1 of the process test was performed; the sluicing system was operated for approximately 7 hours and was ended using the controlled shutdown method when the allowable amount of solids were transferred to 241-AY-102. The phase II test was successful, however, further testing is required to obtain vapor samples at higher emission levels

Tank waste remediation system retrieval and disposal mission - Phase 1: Financial analysis

International Nuclear Information System (INIS)

Bickford, J.C.

1998-01-01

In Section 1.0, an overview of the Financial Analysis was provided and summarized in Table 1 for both the Retrieval and Disposal program and the TWRS project life cycle. A table recaps the pre-Phase 1B analysis budget requirements as discussed in previous sections. Another table in this section shows a similar build-up of costs and the impact of proposed offsets and increases to the pre-Phase 1B analysis. The issues concerning the increased requirements in FY 1998/1999 and the recommended adjustments were discussed. The Phase 1B Program as recommended is achievable. Specific recommendations are as follows: (a) Adopt the revised project baseline as presented in the cited tables; (b) Incorporate the $248.5 million in allowances for risk into the baseline; (c) Develop detailed action plans to realize the costs reduction opportunities; (d) Incorporate site indirect and benefits reduction rates into baseline; (e) Delay non-critical path scope which can be moved beyond FY 1999, as indicated: and (f) Renegotiate the Tri-Party Agreement milestones associated with the current compliance unfunded list for FY 1998

Temporal lobe cortical electrical stimulation during the encoding and retrieval phase reduces false memories.

Directory of Open Access Journals (Sweden)

Paulo S Boggio

Full Text Available A recent study found that false memories were reduced by 36% when low frequency repetitive transcranial magnetic stimulation (rTMS was applied to the left anterior temporal lobe after the encoding (study phase. Here we were interested in the consequences on a false memory task of brain stimulation throughout the encoding and retrieval task phases. We used transcranial direct current stimulation (tDCS because it has been shown to be a useful tool to enhance cognition. Specifically, we examined whether tDCS can induce changes in a task assessing false memories. Based on our preliminary results, three conditions of stimulation were chosen: anodal left/cathodal right anterior temporal lobe (ATL stimulation ("bilateral stimulation"; anodal left ATL stimulation (with a large contralateral cathodal electrode--referred as "unilateral stimulation" and sham stimulation. Our results showed that false memories were reduced significantly after the two active conditions (unilateral and bilateral stimulation as compared with sham stimulation. There were no significant changes in veridical memories. Our findings show that false memories are reduced by 73% when anodal tDCS is applied to the anterior temporal lobes throughout the encoding and retrieval stages, suggesting a possible strategy for improving certain aspects of learning.

Oversampling smoothness: an effective algorithm for phase retrieval of noisy diffraction intensities.

Science.gov (United States)

Rodriguez, Jose A; Xu, Rui; Chen, Chien-Chun; Zou, Yunfei; Miao, Jianwei

2013-04-01

Coherent diffraction imaging (CDI) is high-resolution lensless microscopy that has been applied to image a wide range of specimens using synchrotron radiation, X-ray free-electron lasers, high harmonic generation, soft X-ray lasers and electrons. Despite recent rapid advances, it remains a challenge to reconstruct fine features in weakly scattering objects such as biological specimens from noisy data. Here an effective iterative algorithm, termed oversampling smoothness (OSS), for phase retrieval of noisy diffraction intensities is presented. OSS exploits the correlation information among the pixels or voxels in the region outside of a support in real space. By properly applying spatial frequency filters to the pixels or voxels outside the support at different stages of the iterative process ( i.e. a smoothness constraint), OSS finds a balance between the hybrid input-output (HIO) and error reduction (ER) algorithms to search for a global minimum in solution space, while reducing the oscillations in the reconstruction. Both numerical simulations with Poisson noise and experimental data from a biological cell indicate that OSS consistently outperforms the HIO, ER-HIO and noise robust (NR)-HIO algorithms at all noise levels in terms of accuracy and consistency of the reconstructions. It is expected that OSS will find application in the rapidly growing CDI field, as well as other disciplines where phase retrieval from noisy Fourier magnitudes is needed. The MATLAB (The MathWorks Inc., Natick, MA, USA) source code of the OSS algorithm is freely available from http://www.physics.ucla.edu/research/imaging.

An automated phase correction algorithm for retrieving permittivity and permeability of electromagnetic metamaterials

Directory of Open Access Journals (Sweden)

Z. X. Cao

2014-06-01

Full Text Available To retrieve complex-valued effective permittivity and permeability of electromagnetic metamaterials (EMMs based on resonant effect from scattering parameters using a complex logarithmic function is not inevitable. When complex values are expressed in terms of magnitude and phase, an infinite number of permissible phase angles is permissible due to the multi-valued property of complex logarithmic functions. Special attention needs to be paid to ensure continuity of the effective permittivity and permeability of lossy metamaterials as frequency sweeps. In this paper, an automated phase correction (APC algorithm is proposed to properly trace and compensate phase angles of the complex logarithmic function which may experience abrupt phase jumps near the resonant frequency region of the concerned EMMs, and hence the continuity of the effective optical properties of lossy metamaterials is ensured. The algorithm is then verified to extract effective optical properties from the simulated scattering parameters of the four different types of metamaterial media: a cut-wire cell array, a split ring resonator (SRR cell array, an electric-LC (E-LC resonator cell array, and a combined SRR and wire cell array respectively. The results demonstrate that the proposed algorithm is highly accurate and effective.

Retrieval-practice task affects relationship between working memory capacity and retrieval-induced forgetting.

Science.gov (United States)

Storm, Benjamin C; Bui, Dung C

2016-11-01

Retrieving a subset of items from memory can cause forgetting of other items in memory, a phenomenon referred to as retrieval-induced forgetting (RIF). Individuals who exhibit greater amounts of RIF have been shown to also exhibit superior working memory capacity (WMC) and faster stop-signal reaction times (SSRTs), results which have been interpreted as suggesting that RIF reflects an inhibitory process that is mediated by the processes of executive control. Across four experiments, we sought to further elucidate this issue by manipulating the way in which participants retrieved items during retrieval practice and examining how the resulting effects of forgetting correlated with WMC (Experiments 1-3) and SSRT (Experiment 4). Significant correlations were observed when participants retrieved items from an earlier study phase (within-list retrieval practice), but not when participants generated items from semantic memory (extra-list retrieval practice). These results provide important new insight into the role of executive-control processes in RIF.

Transcatheter Retrieval of Embolized Atrial Septal Defect Occluder Device by Waist Capture Technique.

Science.gov (United States)

Her, Ae-Young; Lim, Kyung-Hun; Shin, Eun-Seok

2018-01-27

This case study describes the successful percutaneous transcatheter retrieval of an embolized Amplatzer occluder device using the "waist capture technique" in a patient with an atrial septal defect. This technique allowed for stability of the Amplatzer device, compression of the atrial discs for easier removal, prevention of further embolization, and minimal injury to vasculature during device retrieval. This novel and effective technique can be used safely for the retrieval of Amplatzer devices in the venous system.

The role of medium range order on phase transitions in chain silicates upon compression

International Nuclear Information System (INIS)

Serghiou, G; Chopelas, A; Boehler, R

2004-01-01

Raman spectroscopic measurements of the tetrahedrally coordinated crystal MnSiO 3 (rhodonite) in an argon pressure medium show that it becomes amorphous above 33 GPa. This observation consolidates our findings and explanation for the global structural trends exhibited by the extended chain silicate family AA'BO 3 (AA': Mg, Ca, Mn, Fe; B: Si) upon compression. In particular, crystals of this family are made of two types of building blocks coined P and C. Those crystals comprised solely of P blocks transform to dense higher coordinated crystalline phases; those comprised of P and C blocks, such as MnSiO 3 rhodonite, become amorphous; whereas those comprised solely of C blocks show both crystalline and amorphous regions upon compression. The reason that this medium range order length scale (building block scale) classification is correlated with the type of transitions taking place upon compression is due to the instability of C blocks and C-P interfaces with respect to P blocks and P-P interfaces at high pressures

Manipulating the retrieved width of stored light pulses

International Nuclear Information System (INIS)

Chen Yongfan; Wang Shihhao; Wang Changyi; Yu, Ite A.

2005-01-01

We have systematically studied the method proposed by Patnaik et al. [Phys. Rev. A 69, 035803 (2004)] that manipulates the retrieval of stored light pulses. The measured probe pulse width of the retrieval is inversely proportional to the intensity of the reading field. We also show that the method does not introduce any phase shift or jump into the retrieved pulses. Our study demonstrates that the distortion at the output of the light storage can be corrected by manipulating the retrieval process and the phase information of the stored pulses can remain intact during the process

Asymmetric double-image encryption method by using iterative phase retrieval algorithm in fractional Fourier transform domain

Science.gov (United States)

Sui, Liansheng; Lu, Haiwei; Ning, Xiaojuan; Wang, Yinghui

2014-02-01

A double-image encryption scheme is proposed based on an asymmetric technique, in which the encryption and decryption processes are different and the encryption keys are not identical to the decryption ones. First, a phase-only function (POF) of each plain image is retrieved by using an iterative process and then encoded into an interim matrix. Two interim matrices are directly modulated into a complex image by using the convolution operation in the fractional Fourier transform (FrFT) domain. Second, the complex image is encrypted into the gray scale ciphertext with stationary white-noise distribution by using the FrFT. In the encryption process, three random phase functions are used as encryption keys to retrieve the POFs of plain images. Simultaneously, two decryption keys are generated in the encryption process, which make the optical implementation of the decryption process convenient and efficient. The proposed encryption scheme has high robustness to various attacks, such as brute-force attack, known plaintext attack, cipher-only attack, and specific attack. Numerical simulations demonstrate the validity and security of the proposed method.

High Bit-Depth Medical Image Compression With HEVC.

Science.gov (United States)

Parikh, Saurin S; Ruiz, Damian; Kalva, Hari; Fernandez-Escribano, Gerardo; Adzic, Velibor

2018-03-01

Efficient storing and retrieval of medical images has direct impact on reducing costs and improving access in cloud-based health care services. JPEG 2000 is currently the commonly used compression format for medical images shared using the DICOM standard. However, new formats such as high efficiency video coding (HEVC) can provide better compression efficiency compared to JPEG 2000. Furthermore, JPEG 2000 is not suitable for efficiently storing image series and 3-D imagery. Using HEVC, a single format can support all forms of medical images. This paper presents the use of HEVC for diagnostically acceptable medical image compression, focusing on compression efficiency compared to JPEG 2000. Diagnostically acceptable lossy compression and complexity of high bit-depth medical image compression are studied. Based on an established medically acceptable compression range for JPEG 2000, this paper establishes acceptable HEVC compression range for medical imaging applications. Experimental results show that using HEVC can increase the compression performance, compared to JPEG 2000, by over 54%. Along with this, a new method for reducing computational complexity of HEVC encoding for medical images is proposed. Results show that HEVC intra encoding complexity can be reduced by over 55% with negligible increase in file size.

Interfering effects of retrieval in learning new information.

Science.gov (United States)

Finn, Bridgid; Roediger, Henry L

2013-11-01

In 7 experiments, we explored the role of retrieval in associative updating, that is, in incorporating new information into an associative memory. We tested the hypothesis that retrieval would facilitate incorporating a new contextual detail into a learned association. Participants learned 3 pieces of information-a person's face, name, and profession (in Experiments 1-5). In the 1st phase, participants in all conditions learned faces and names. In the 2nd phase, participants either restudied the face-name pair (the restudy condition) or were given the face and asked to retrieve the name (the test condition). In the 3rd phase, professions were presented for study just after restudy or testing. Our prediction was that the new information (the profession) would be more readily learned following retrieval of the face-name association compared to restudy of the face-name association. However, we found that the act of retrieval generally undermined acquisition of new associations rather than facilitating them. This detrimental effect emerged on both immediate and delayed tests. Further, the effect was not due to selective attention to feedback because we found impairment whether or not feedback was provided after the Phase 2 test. The data are novel in showing that the act of retrieving information can inhibit the ability to learn new information shortly thereafter. The results are difficult to accommodate within current theories that mostly emphasize benefits of retrieval for learning. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Color image encryption using random transforms, phase retrieval, chaotic maps, and diffusion

Science.gov (United States)

Annaby, M. H.; Rushdi, M. A.; Nehary, E. A.

2018-04-01

The recent tremendous proliferation of color imaging applications has been accompanied by growing research in data encryption to secure color images against adversary attacks. While recent color image encryption techniques perform reasonably well, they still exhibit vulnerabilities and deficiencies in terms of statistical security measures due to image data redundancy and inherent weaknesses. This paper proposes two encryption algorithms that largely treat these deficiencies and boost the security strength through novel integration of the random fractional Fourier transforms, phase retrieval algorithms, as well as chaotic scrambling and diffusion. We show through detailed experiments and statistical analysis that the proposed enhancements significantly improve security measures and immunity to attacks.

Assessment of myocardial bridge by cardiac CT: Intracoronary transluminal attenuation gradient derived from diastolic phase predicts systolic compression

Energy Technology Data Exchange (ETDEWEB)

Yu, Meng Meng; Zhang, Yang; Li, Yue Hua; Li, Wen Bin; Li, Ming Hua; Zhang, Jiayin [Institute of Diagnostic and Interventional Radiology, Shanghai Jiao Tong University Affiliated Sixth People' s Hospital, Shangha (China)

2017-08-01

To study the predictive value of transluminal attenuation gradient (TAG) derived from diastolic phase of coronary computed tomography angiography (CCTA) for identifying systolic compression of myocardial bridge (MB). Consecutive patients diagnosed with MB based on CCTA findings and without obstructive coronary artery disease were retrospectively enrolled. In total, 143 patients with 144 MBs were included in the study. Patients were classified into three groups: without systolic compression, with systolic compression < 50%, and with systolic compression ≥ 50%. TAG was defined as the linear regression coefficient between intraluminal attenuation in Hounsfield units (HU) and length from the vessel ostium. Other indices such as the length and depth of the MB were also recorded. TAG was the lowest in MB patients with systolic compression ≥ 50% (-19.9 ± 8.7 HU/10 mm). Receiver operating characteristic curve analysis was performed to determine the optimal cutoff values for identifying systolic compression ≥ 50%. The result indicated an optimal cutoff value of TAG as -18.8 HU/10 mm (area under curve = 0.778, p < 0.001), which yielded higher sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy (54.1, 80.5, 72.8, and 75.0%, respectively). In addition, the TAG of MB with diastolic compression was significantly lower than the TAG of MB without diastolic compression (-21.4 ± 4.8 HU/10 mm vs. -12.7 ± 8 HU/10 mm, p < 0.001). TAG was a better predictor of MB with systolic compression ≥ 50%, compared to the length or depth of the MB. The TAG of MB with persistent diastolic compression was significantly lower than the TAG without diastolic compression.

Temporal compression in episodic memory for real-life events.

Science.gov (United States)

Jeunehomme, Olivier; Folville, Adrien; Stawarczyk, David; Van der Linden, Martial; D'Argembeau, Arnaud

2018-07-01

Remembering an event typically takes less time than experiencing it, suggesting that episodic memory represents past experience in a temporally compressed way. Little is known, however, about how the continuous flow of real-life events is summarised in memory. Here we investigated the nature and determinants of temporal compression by directly comparing memory contents with the objective timing of events as measured by a wearable camera. We found that episodic memories consist of a succession of moments of prior experience that represent events with varying compression rates, such that the density of retrieved information is modulated by goal processing and perceptual changes. Furthermore, the results showed that temporal compression rates remain relatively stable over one week and increase after a one-month delay, particularly for goal-related events. These data shed new light on temporal compression in episodic memory and suggest that compression rates are adaptively modulated to maintain current goal-relevant information.

Pulse Compression of Phase-matched High Harmonic Pulses from a Time-Delay Compensated Monochromator

Directory of Open Access Journals (Sweden)

Ito Motohiko

2013-03-01

Full Text Available Pulse compression of single 32.6-eV high harmonic pulses from a time-delay compensated monochromator was demonstrated down to 11±3 fs by compensating the pulse front tilt. The photon flux was intensified up to 5.7×109 photons/s on target by implementing high harmonic generation under a phase matching condition in a hollow fiber used for increasing the interaction length.

Study of CSR longitudinal bunch compression cavity

International Nuclear Information System (INIS)

Yin Dayu; Li Peng; Liu Yong; Xie Qingchun

2009-01-01

The scheme of longitudinal bunch compression cavity for the Cooling Storage Ring (CSR)is an important issue. Plasma physics experiments require high density heavy ion beam and short pulsed bunch,which can be produced by non-adiabatic compression of bunch implemented by a fast compression with 90 degree rotation in the longitudinal phase space. The phase space rotation in fast compression is initiated by a fast jump of the RF-voltage amplitude. For this purpose, the CSR longitudinal bunch compression cavity, loaded with FINEMET-FT-1M is studied and simulated with MAFIA code. In this paper, the CSR longitudinal bunch compression cavity is simulated and the initial bunch length of 238 U 72+ with 250 MeV/u will be compressed from 200 ns to 50 ns.The construction and RF properties of the CSR longitudinal bunch compression cavity are simulated and calculated also with MAFIA code. The operation frequency of the cavity is 1.15 MHz with peak voltage of 80 kV, and the cavity can be used to compress heavy ions in the CSR. (authors)

Retrievability in an ethical perspective

International Nuclear Information System (INIS)

Thunberg, A.-M.

2000-01-01

At the outset, a short summary is given of how the ethical discussion developed historically, all from the so-called double KASAM principle of 1987 - safety in operation, combined with reparability, with controls not necessary, but not impossible - until the phase of focusing on retrievability as a result of a deepened ethical discussion. The ethical development is seen schematically according to two phases. The concept of retrievability functions as a symbol for the shift from the first to the second phase. Intergenerational equity is interpreted as an obligation to maximize the safety of future generations, whilst imposing a minimum of risks, burdens and costs. The basic disposal concept is an intrinsically definitive and non-retrievable one. The second phase carries over from the first its principle of the total responsibility of our generation, but interprets the principle of intergenerational equity as also including equal opportunities. This leads to the following conclusion: What is at stake is a precarious act of balance, with a preserved equal weight for the two principles in each decision and every measure. Finally, some questions for future treatment are put, and the author draws the following conclusions. We can hardly advance further than to manufacture an interactive waste management system, allowing us to involve present and future generations in an open, flexible, and non-preconstrained decision making process. In such a process, retrievability presents itself as an inescapable dimension. But at the same time we cannot guarantee future generations freedom to act without providing for them a repository which is designed to be finally closed. (author)

An investigation of response competition in retrieval-induced forgetting

Directory of Open Access Journals (Sweden)

Gina A. Glanc

2015-12-01

Full Text Available It has been demonstrated that retrieval practice on a subset of studied items can cause forgetting of different related studied items. This retrieval-induced forgetting (the RIF effect has been demonstrated in a variety of recall studies and has been attributed to an inhibitory mechanism activated during retrieval practice by competition for a shared retrieval cue. The current study generalizes the RIF effect to recognition memory and investigates this competition assumption. Experiment 1 demonstrated an effect of RIF effect in item recognition with incidental encoding of category-exemplar association during the study phase. Experiment 2 demonstrated evidence of RIF with use of an independent retrieval cue during retrieval practice. Results from this study indicate that response competition may occur outside of the retrieval-practice phase, or may not be limited to situations where there is an overt link to a shared category cue.

The possibilities of compressed sensing based migration

KAUST Repository

Aldawood, Ali

2013-09-22

Linearized waveform inversion or Least-square migration helps reduce migration artifacts caused by limited acquisition aperture, coarse sampling of sources and receivers, and low subsurface illumination. However, leastsquare migration, based on L2-norm minimization of the misfit function, tends to produce a smeared (smoothed) depiction of the true subsurface reflectivity. Assuming that the subsurface reflectivity distribution is a sparse signal, we use a compressed-sensing (Basis Pursuit) algorithm to retrieve this sparse distribution from a small number of linear measurements. We applied a compressed-sensing algorithm to image a synthetic fault model using dense and sparse acquisition geometries. Tests on synthetic data demonstrate the ability of compressed-sensing to produce highly resolved migrated images. We, also, studied the robustness of the Basis Pursuit algorithm in the presence of Gaussian random noise.

The possibilities of compressed sensing based migration

KAUST Repository

Aldawood, Ali; Hoteit, Ibrahim; Alkhalifah, Tariq Ali

2013-01-01

Linearized waveform inversion or Least-square migration helps reduce migration artifacts caused by limited acquisition aperture, coarse sampling of sources and receivers, and low subsurface illumination. However, leastsquare migration, based on L2-norm minimization of the misfit function, tends to produce a smeared (smoothed) depiction of the true subsurface reflectivity. Assuming that the subsurface reflectivity distribution is a sparse signal, we use a compressed-sensing (Basis Pursuit) algorithm to retrieve this sparse distribution from a small number of linear measurements. We applied a compressed-sensing algorithm to image a synthetic fault model using dense and sparse acquisition geometries. Tests on synthetic data demonstrate the ability of compressed-sensing to produce highly resolved migrated images. We, also, studied the robustness of the Basis Pursuit algorithm in the presence of Gaussian random noise.

Structural Phase Transition and Compressibility of CaF2 Nanocrystals under High Pressure

Directory of Open Access Journals (Sweden)

Jingshu Wang

2018-05-01

Full Text Available The structural phase transition and compressibility of CaF2 nanocrystals with size of 23 nm under high pressure were investigated by synchrotron X-ray diffraction measurement. A pressure-induced fluorite to α-PbCl2-type phase transition starts at 9.5 GPa and completes at 20.2 GPa. The phase-transition pressure is lower than that of 8 nm CaF2 nanocrystals and closer to bulk CaF2. Upon decompression, the fluorite and α-PbCl2-type structure co-exist at the ambient pressure. The bulk modulus B0 of the 23 nm CaF2 nanocrystals for the fluorite and α-PbCl2-type phase are 103(2 and 78(2 GPa, which are both larger than those of the bulk CaF2. The CaF2 nanocrystals exhibit obviously higher incompressibility compare to bulk CaF2. Further analysis demonstrates that the defect effect in our CaF2 nanocrystals plays a dominant role in the structural stability.

Compact Representation of High-Dimensional Feature Vectors for Large-Scale Image Recognition and Retrieval.

Science.gov (United States)

Zhang, Yu; Wu, Jianxin; Cai, Jianfei

2016-05-01

In large-scale visual recognition and image retrieval tasks, feature vectors, such as Fisher vector (FV) or the vector of locally aggregated descriptors (VLAD), have achieved state-of-the-art results. However, the combination of the large numbers of examples and high-dimensional vectors necessitates dimensionality reduction, in order to reduce its storage and CPU costs to a reasonable range. In spite of the popularity of various feature compression methods, this paper shows that the feature (dimension) selection is a better choice for high-dimensional FV/VLAD than the feature (dimension) compression methods, e.g., product quantization. We show that strong correlation among the feature dimensions in the FV and the VLAD may not exist, which renders feature selection a natural choice. We also show that, many dimensions in FV/VLAD are noise. Throwing them away using feature selection is better than compressing them and useful dimensions altogether using feature compression methods. To choose features, we propose an efficient importance sorting algorithm considering both the supervised and unsupervised cases, for visual recognition and image retrieval, respectively. Combining with the 1-bit quantization, feature selection has achieved both higher accuracy and less computational cost than feature compression methods, such as product quantization, on the FV and the VLAD image representations.

An implicit numerical model for multicomponent compressible two-phase flow in porous media

Science.gov (United States)

Zidane, Ali; Firoozabadi, Abbas

2015-11-01

We introduce a new implicit approach to model multicomponent compressible two-phase flow in porous media with species transfer between the phases. In the implicit discretization of the species transport equation in our formulation we calculate for the first time the derivative of the molar concentration of component i in phase α (cα, i) with respect to the total molar concentration (ci) under the conditions of a constant volume V and temperature T. The species transport equation is discretized by the finite volume (FV) method. The fluxes are calculated based on powerful features of the mixed finite element (MFE) method which provides the pressure at grid-cell interfaces in addition to the pressure at the grid-cell center. The efficiency of the proposed model is demonstrated by comparing our results with three existing implicit compositional models. Our algorithm has low numerical dispersion despite the fact it is based on first-order space discretization. The proposed algorithm is very robust.

Mechanics of occurrence of critical flow in compressible two-phase flow

International Nuclear Information System (INIS)

Katto, Yoshiro; Sudo, Yukio

1976-01-01

Fundamental framework of mechanics for the occurrence of critical flow is investigated, following the principle that the critical flow appears as a limit in a continuous change of state of flow along a nozzle (or a pipe) and should be derived only from simultaneous mechanical equations concerned with the flow. Mathematical procedures with which the critical flow: (i) the single phase flow of an arbitrary fluid, unrestricted by the equation of state of ideal gas, where the number of simultaneous equations is equal to the number of independent variables, and (ii) the one-component, separated two-phase flow under saturated condition, where the number of equations exceeds that of variables. In each case, interesting mechanism of leading to the occurrence of a limiting state of flow at a definite cross-section in a nozzle (incl. a pipe) is clarified, and a definite state of flow at the critical cross-section is also determined. Then, the analysis is extended to the critical flow which should appear in the completely isolated and the homogeneously dispersed, two-component, two-phase flow (composed of a compressible and an incompressible substance). It is found that the analyses of these special flow patterns provide several supplementary information to the mechanics of critical flow. (auth.)

Robust information encryption diffractive-imaging-based scheme with special phase retrieval algorithm for a customized data container

Science.gov (United States)

Qin, Yi; Wang, Zhipeng; Wang, Hongjuan; Gong, Qiong; Zhou, Nanrun

2018-06-01

The diffractive-imaging-based encryption (DIBE) scheme has aroused wide interesting due to its compact architecture and low requirement of conditions. Nevertheless, the primary information can hardly be recovered exactly in the real applications when considering the speckle noise and potential occlusion imposed on the ciphertext. To deal with this issue, the customized data container (CDC) into DIBE is introduced and a new phase retrieval algorithm (PRA) for plaintext retrieval is proposed. The PRA, designed according to the peculiarity of the CDC, combines two key techniques from previous approaches, i.e., input-support-constraint and median-filtering. The proposed scheme can guarantee totally the reconstruction of the primary information despite heavy noise or occlusion and its effectiveness and feasibility have been demonstrated with simulation results.

Mechanical behavior of silicon carbide nanoparticles under uniaxial compression

Energy Technology Data Exchange (ETDEWEB)

He, Qiuxiang; Fei, Jing; Tang, Chao; Zhong, Jianxin; Meng, Lijun, E-mail: ljmeng@xtu.edu.cn [Xiangtan University, Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, Faculty of School of Physics and Optoelectronics (China)

2016-03-15

The mechanical behavior of SiC nanoparticles under uniaxial compression was investigated using an atomic-level compression simulation technique. The results revealed that the mechanical deformation of SiC nanocrystals is highly dependent on compression orientation, particle size, and temperature. A structural transformation from the original zinc-blende to a rock-salt phase is identified for SiC nanoparticles compressed along the [001] direction at low temperature. However, the rock-salt phase is not observed for SiC nanoparticles compressed along the [110] and [111] directions irrespective of size and temperature. The high-pressure-generated rock-salt phase strongly affects the mechanical behavior of the nanoparticles, including their hardness and deformation process. The hardness of [001]-compressed nanoparticles decreases monotonically as their size increases, different from that of [110] and [111]-compressed nanoparticles, which reaches a maximal value at a critical size and then decreases. Additionally, a temperature-dependent mechanical response was observed for all simulated SiC nanoparticles regardless of compression orientation and size. Interestingly, the hardness of SiC nanocrystals with a diameter of 8 nm compressed in [001]-orientation undergoes a steep decrease at 0.1–200 K and then a gradual decline from 250 to 1500 K. This trend can be attributed to different deformation mechanisms related to phase transformation and dislocations. Our results will be useful for practical applications of SiC nanoparticles under high pressure.

QCD phase diagram : heating or compressing ?

CERN Multimedia

Maire, Antonin

2011-01-01

The sketch tries to address the question of the difference between heating and compressing the baryonic matter in relativistic heavy-ion collisions, i.e. how one can reach in the laboratory "high" temperature at "low" net baryon density (baryon chemical potential) or "low" temperature at "high" net baryon density.

A micromechanical four-phase model to predict the compressive failure surface of cement concrete

Directory of Open Access Journals (Sweden)

A. Caporale,

2014-07-01

Full Text Available In this work, a micromechanical model is used in order to predict the failure surface of cement concrete subject to multi-axial compression. In the adopted model, the concrete material is schematised as a composite with the following constituents: coarse aggregate (gravel, fine aggregate (sand and cement paste. The cement paste contains some voids which grow during the loading process. In fact, the non-linear behavior of the concrete is attributed to the creation of cracks in the cement paste; the effect of the cracks is taken into account by introducing equivalent voids (inclusions with zero stiffness in the cement paste. The three types of inclusions (namely gravel, sand and voids have different scales, so that the overall behavior of the concrete is obtained by the composition of three different homogenizations; in the sense that the concrete is regarded as the homogenized material of the two-phase composite constituted of the gravel and the mortar; in turn, the mortar is the homogenized material of the two-phase composite constituted of the sand inclusions and a (porous cement paste matrix; finally, the (porous cement paste is the homogenized material of the two-phase composite constituted of voids and the pure paste. The pure paste represents the cement paste before the loading process, so that it does not contain voids or other defects due to the loading process. The abovementioned three homogenizations are realized with the predictive scheme of Mori-Tanaka in conjunction with the Eshelby method. The adopted model can be considered an attempt to find micromechanical tools able to capture peculiar aspects of the cement concrete in load cases of uni-axial and multi-axial compression. Attributing the non-linear behavior of concrete to the creation of equivalent voids in the cement paste provides correspondence with many phenomenological aspects of concrete behavior. Trying to improve this correspondence, the influence of the parameters of the

The second-order differential phase contrast and its retrieval for imaging with x-ray Talbot interferometry

International Nuclear Information System (INIS)

Yang Yi; Tang Xiangyang

2012-01-01

Purpose: The x-ray differential phase contrast imaging implemented with the Talbot interferometry has recently been reported to be capable of providing tomographic images corresponding to attenuation-contrast, phase-contrast, and dark-field contrast, simultaneously, from a single set of projection data. The authors believe that, along with small-angle x-ray scattering, the second-order phase derivative Φ ″ s (x) plays a role in the generation of dark-field contrast. In this paper, the authors derive the analytic formulae to characterize the contribution made by the second-order phase derivative to the dark-field contrast (namely, second-order differential phase contrast) and validate them via computer simulation study. By proposing a practical retrieval method, the authors investigate the potential of second-order differential phase contrast imaging for extensive applications. Methods: The theoretical derivation starts at assuming that the refractive index decrement of an object can be decomposed into δ=δ s +δ f , where δ f corresponds to the object's fine structures and manifests itself in the dark-field contrast via small-angle scattering. Based on the paraxial Fresnel-Kirchhoff theory, the analytic formulae to characterize the contribution made by δ s , which corresponds to the object's smooth structures, to the dark-field contrast are derived. Through computer simulation with specially designed numerical phantoms, an x-ray differential phase contrast imaging system implemented with the Talbot interferometry is utilized to evaluate and validate the derived formulae. The same imaging system is also utilized to evaluate and verify the capability of the proposed method to retrieve the second-order differential phase contrast for imaging, as well as its robustness over the dimension of detector cell and the number of steps in grating shifting. Results: Both analytic formulae and computer simulations show that, in addition to small-angle scattering, the

CEPRAM: Compression for Endurance in PCM RAM

OpenAIRE

González Alberquilla, Rodrigo; Castro Rodríguez, Fernando; Piñuel Moreno, Luis; Tirado Fernández, Francisco

2017-01-01

We deal with the endurance problem of Phase Change Memories (PCM) by proposing Compression for Endurance in PCM RAM (CEPRAM), a technique to elongate the lifespan of PCM-based main memory through compression. We introduce a total of three compression schemes based on already existent schemes, but targeting compression for PCM-based systems. We do a two-level evaluation. First, we quantify the performance of the compression, in terms of compressed size, bit-flips and how they are affected by e...

Anomalous lattice compressibility of hexagonal Eu{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Irshad, K.A.; Chandra Shekar, N.V., E-mail: chandru@igcar.gov.in

2017-07-01

Monoclinic Eu{sub 2}O{sub 3} was investigated in a Mao-Bell type diamond anvil cell using angle dispersive x-ray diffraction up to a pressure of 26 GPa. Pressure induced structural phase transition from monoclinic to hexagonal phase was observed at 4.3 GPa with 2% volume collapse. Birch –Murnaghan equation of state fit to the pressure volume data yielded a bulk modulus of 159(9) GPa and 165(6) GPa for the monoclinic and hexagonal phases respectively. Equation of state fitting to the structural parameters yielded an axial compressibility of β{sub a} > β{sub c} > β{sub b} for the parent monoclinic phase, showing the least compressibility along b axis. Contrary to the available reports, an anomalous lattice compressibility behavior is observed for the high pressure hexagonal phase, characterized by pronounced hardening of a axis above 15 GPa. The observed incompressible nature of the hexagonal a axis in the pressure range 15–25 GPa is found to be compensated by doubling the compressibility along the c axis. - Highlights: • Structural phase transition in Eu{sub 2}O{sub 3} from monoclinic to hexagonal phase. • Anomalous lattice compressibility in the hexagonal phase has reported first time. • Quantitative analysis of lattice compressibility.

Comparison of single distance phase retrieval algorithms by considering different object composition and the effect of statistical and structural noise.

Science.gov (United States)

Chen, R C; Rigon, L; Longo, R

2013-03-25

Phase retrieval is a technique for extracting quantitative phase information from X-ray propagation-based phase-contrast tomography (PPCT). In this paper, the performance of different single distance phase retrieval algorithms will be investigated. The algorithms are herein called phase-attenuation duality Born Algorithm (PAD-BA), phase-attenuation duality Rytov Algorithm (PAD-RA), phase-attenuation duality Modified Bronnikov Algorithm (PAD-MBA), phase-attenuation duality Paganin algorithm (PAD-PA) and phase-attenuation duality Wu Algorithm (PAD-WA), respectively. They are all based on phase-attenuation duality property and on weak absorption of the sample and they employ only a single distance PPCT data. In this paper, they are investigated via simulated noise-free PPCT data considering the fulfillment of PAD property and weakly absorbing conditions, and with experimental PPCT data of a mixture sample containing absorbing and weakly absorbing materials, and of a polymer sample considering different degrees of statistical and structural noise. The simulation shows all algorithms can quantitatively reconstruct the 3D refractive index of a quasi-homogeneous weakly absorbing object from noise-free PPCT data. When the weakly absorbing condition is violated, the PAD-RA and PAD-PA/WA obtain better result than PAD-BA and PAD-MBA that are shown in both simulation and mixture sample results. When considering the statistical noise, the contrast-to-noise ratio values decreases as the photon number is reduced. The structural noise study shows that the result is progressively corrupted by ring-like artifacts with the increase of structural noise (i.e. phantom thickness). The PAD-RA and PAD-PA/WA gain better density resolution than the PAD-BA and PAD-MBA in both statistical and structural noise study.

Compressibility and thermal expansion of cubic silicon nitride

DEFF Research Database (Denmark)

Jiang, Jianzhong; Lindelov, H.; Gerward, Leif

2002-01-01

The compressibility and thermal expansion of the cubic silicon nitride (c-Si3N4) phase have been investigated by performing in situ x-ray powder-diffraction measurements using synchrotron radiation, complemented with computer simulations by means of first-principles calculations. The bulk...... compressibility of the c-Si3N4 phase originates from the average of both Si-N tetrahedral and octahedral compressibilities where the octahedral polyhedra are less compressible than the tetrahedral ones. The origin of the unit cell expansion is revealed to be due to the increase of the octahedral Si-N and N-N bond...

RELAP-7 Progress Report: A Mathematical Model for 1-D Compressible, Single-Phase Flow Through a Branching Junction

Energy Technology Data Exchange (ETDEWEB)

Berry, R. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2017-08-14

In the literature, the abundance of pipe network junction models, as well as inclusion of dissipative losses between connected pipes with loss coefficients, has been treated using the incompressible flow assumption of constant density. This approach is fundamentally, physically wrong for compressible flow with density change. This report introduces a mathematical modeling approach for general junctions in piping network systems for which the transient flows are compressible and single-phase. The junction could be as simple as a 1-pipe input and 1-pipe output with differing pipe cross-sectional areas for which a dissipative loss is necessary, or it could include an active component, between an inlet pipe and an outlet pipe, such as a pump or turbine. In this report, discussion will be limited to the former. A more general branching junction connecting an arbitrary number of pipes with transient, 1-D compressible single-phase flows is also presented. These models will be developed in a manner consistent with the use of a general equation of state like, for example, the recent Spline-Based Table Look-up method [1] for incorporating the IAPWS-95 formulation [2] to give accurate and efficient calculations for properties for water and steam with RELAP-7 [3].

Masker phase effects in normal-hearing and hearing-impaired listeners: evidence for peripheral compression at low signal frequencies

DEFF Research Database (Denmark)

Oxenham, Andrew J.; Dau, Torsten

2004-01-01

curvature. Results from 12 listeners with sensorineural hearing loss showed reduced masker phase effects, when compared with data from normal-hearing listeners, at both 250- and 1000-Hz signal frequencies. The effects of hearing impairment on phase-related masking differences were not well simulated...... are affected by a common underlying mechanism, presumably related to cochlear outer hair cell function. The results also suggest that normal peripheral compression remains strong even at 250 Hz....

Context-Aware Image Compression.

Directory of Open Access Journals (Sweden)

Jacky C K Chan

Full Text Available We describe a physics-based data compression method inspired by the photonic time stretch wherein information-rich portions of the data are dilated in a process that emulates the effect of group velocity dispersion on temporal signals. With this coding operation, the data can be downsampled at a lower rate than without it. In contrast to previous implementation of the warped stretch compression, here the decoding can be performed without the need of phase recovery. We present rate-distortion analysis and show improvement in PSNR compared to compression via uniform downsampling.

Combined multi-plane phase retrieval and super-resolution optical fluctuation imaging for 4D cell microscopy

Science.gov (United States)

Descloux, A.; Grußmayer, K. S.; Bostan, E.; Lukes, T.; Bouwens, A.; Sharipov, A.; Geissbuehler, S.; Mahul-Mellier, A.-L.; Lashuel, H. A.; Leutenegger, M.; Lasser, T.

2018-03-01

Super-resolution fluorescence microscopy provides unprecedented insight into cellular and subcellular structures. However, going `beyond the diffraction barrier' comes at a price, since most far-field super-resolution imaging techniques trade temporal for spatial super-resolution. We propose the combination of a novel label-free white light quantitative phase imaging with fluorescence to provide high-speed imaging and spatial super-resolution. The non-iterative phase retrieval relies on the acquisition of single images at each z-location and thus enables straightforward 3D phase imaging using a classical microscope. We realized multi-plane imaging using a customized prism for the simultaneous acquisition of eight planes. This allowed us to not only image live cells in 3D at up to 200 Hz, but also to integrate fluorescence super-resolution optical fluctuation imaging within the same optical instrument. The 4D microscope platform unifies the sensitivity and high temporal resolution of phase imaging with the specificity and high spatial resolution of fluorescence microscopy.

Surpassing the Theoretical 1-Norm Phase Transition in Compressive Sensing by Tuning the Smoothed L0 Algorithm

DEFF Research Database (Denmark)

Oxvig, Christian Schou; Pedersen, Patrick Steffen; Arildsen, Thomas

2013-01-01

Reconstruction of an undersampled signal is at the root of compressive sensing: when is an algorithm capable of reconstructing the signal? what quality is achievable? and how much time does reconstruction require? We have considered the worst-case performance of the smoothed ℓ0 norm reconstruction...... algorithm in a noiseless setup. Through an empirical tuning of its parameters, we have improved the phase transition (capabilities) of the algorithm for fixed quality and required time. In this paper, we present simulation results that show a phase transition surpassing that of the theoretical ℓ1 approach......: the proposed modified algorithm obtains 1-norm phase transition with greatly reduced required computation time....

Finite-size effects in thermodynamics: Negative compressibility and global instability in two-phase systems

Science.gov (United States)

Todoshchenko, I.

2018-04-01

We have measured the equilibrium melting pressure of helium-4 as a function of the crystal size. Negative compressibility of a liquid with an inclusion of solid seed is predicted theoretically and verified experimentally with helium-4 crystal-superfluid system at 0.15 K. This two-phase system is shown to be stable if the crystal size is large enough, which is proven by the experiment. Crystal seeds that are too small spontaneously either melt completely or grow to a large enough size.

Fourier phasing with phase-uncertain mask

International Nuclear Information System (INIS)

Fannjiang, Albert; Liao, Wenjing

2013-01-01

Fourier phasing is the problem of retrieving Fourier phase information from Fourier intensity data. The standard Fourier phase retrieval (without a mask) is known to have many solutions which cause the standard phasing algorithms to stagnate and produce wrong or inaccurate solutions. In this paper Fourier phase retrieval is carried out with the introduction of a randomly fabricated mask in measurement and reconstruction. Highly probable uniqueness of solution, up to a global phase, was previously proved with exact knowledge of the mask. Here the uniqueness result is extended to the case where only rough information about the mask’s phases is assumed. The exponential probability bound for uniqueness is given in terms of the uncertainty-to-diversity ratio of the unknown mask. New phasing algorithms alternating between the object update and the mask update are systematically tested and demonstrated to have the capability of recovering both the object and the mask (within the object support) simultaneously, consistent with the uniqueness result. Phasing with a phase-uncertain mask is shown to be robust with respect to the correlation in the mask as well as the Gaussian and Poisson noises. (paper)

How Often and Why MODIS Cloud Property Retrievals Fail for Liquid-Phase Clouds over Ocean? a Comprehensive Analysis Based on a-Train Observations

Science.gov (United States)

Zhang, Z.; Cho, H. M.; Platnick, S. E.; Meyer, K.; Lebsock, M. D.

2014-12-01

The cloud optical thickness (τ) and droplet effective radius (re) are two key cloud parameters retrieved by MODIS (Moderate Resolution Imaging Spectroradiometer). These MODIS cloud products are widely used in a broad range of earth system science applications. In this paper, we present a comprehensive analysis of the failed cloud τ and/or re retrievals for liquid-phase clouds over ocean in the Collection 6 MODIS cloud product. The main findings from this study are summarized as follows: MODIS retrieval failure rates for marine boundary layer (MBL) clouds have a strong dependence on the spectral combination used for retrieval (e.g., 0.86 + 2.1 µm vs. 0.8 + 3.7 µm) and the cloud morphology (i.e., "good" pixels vs. partly cloudy (PCL) pixels). Combining all clear-sky-restoral (CSR) categories (CSR=0,1 and 3), the 0.86 + 2.1 µm and 0.86 + 3.7 µm spectral combinations have an overall failure rate of about 20% and 12%, respectively (See figure below). The PCL pixels (CSR=1 & 3) have significantly higher failure rates and contribute more to the total failure population than the "good" (CSR=0) pixels. The majority of the failed retrievals are caused by the re too large failure, which explains about 85% and 70% of the failed 0.86 + 2.1 µm and 0.86 + 3.7 µm retrievals, respectively. The remaining failures are either due to the re too small failure or τ retrieval failure. The geographical distribution of failure rates has a significant dependence on cloud regime, lower over the coastal stratocumulus cloud regime and higher over the broken trade-wind cumulus cloud regime over open oceans. Enhanced retrieval failure rates are found when MBL clouds have high sub-pixel inhomogeneity , or are located at special Sun-satellite viewing geometries, such as sunglint, large viewing or solar zenith angle, or cloudbow and glory angles, or subject to cloud masking, cloud overlapping and/or cloud phase retrieval issues. About 80% of the failure retrievals can be attributed to at

Retrieval of past and future positive and negative autobiographical experiences.

Science.gov (United States)

García-Bajos, Elvira; Migueles, Malen

2017-09-01

We studied retrieval-induced forgetting for past or future autobiographical experiences. In the study phase, participants were given cues to remember past autobiographical experiences or to think about experiences that may occur in the future. In both conditions, half of the experiences were positive and half negative. In the retrieval-practice phase, for past and future experiences, participants retrieved either half of the positive or negative experiences using cued recall, or capitals of the world (control groups). Retrieval practice produced recall facilitation and enhanced memory for the practised positive and negative past and future experiences. While retrieval practice on positive experiences did not impair the recall of other positive experiences, we found inhibition for negative past and future experiences when participants practised negative experiences. Furthermore, retrieval practice on positive future experiences inhibited negative future experiences. These positivity biases for autobiographical memory may have practical implications for treatment of emotional disorders.

Cooperative Telerobotic Retrieval system Phase 1 technology evaluation report

Energy Technology Data Exchange (ETDEWEB)

Hyde, R.A.; Croft, K.M.

1995-03-01

This document describes the results from the Cooperative Telerobotic Retrieval demonstration and testing conducted at the Idaho National Engineering Laboratory during December 1994 and January 1995. The purpose of the demonstration was to ascertain the feasibility of the system for deploying tools both independently and cooperatively for supporting remote characterization and removal of buried waste in a safe manner and in compliance with all regulatory requirements. The procedures and goals of the demonstration were previously defined in the Cooperative Telerobotic Retrieval System Test Plan for Fiscal Year 1994, which served as a guideline for evaluating the system.

Strategies for Time-resolved X-ray Diffraction of Phase Transitions with Laser Compression

Science.gov (United States)

Benedetti, Laura Robin; Eggert, J. H.; Bradley, D. K.; Bell, P. M.; Kilkenny, J. D.; Palmer, N.; Petre, R. B.; Rygg, J. R.; Sorce, C.; Collins, G. W.; Boehly, T. R.

2017-10-01

As part of a program to document kinetics of phase transitions under laser-driven dynamic compression, we are designing a platform to make multiple x-ray diffraction measurements during a single laser experiment. Our plans include experimental development at Omega-EP and eventual implementation at NIF. We will present our strategy for designing a robust platform that can effectively document a wide variety of phase transformations by utilizing both streaked and multiple-frame imaging detectors. Preliminary designs utilize a novel CMOS detector designed by Sandia National Lab. Our initial experiments include scoping studies that will focus on photometrics and shielding requirements in the high EMP environment close to the target. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC, LLNL-ABS-734470.

Recognizable or Not: Towards Image Semantic Quality Assessment for Compression

Science.gov (United States)

Liu, Dong; Wang, Dandan; Li, Houqiang

2017-12-01

Traditionally, image compression was optimized for the pixel-wise fidelity or the perceptual quality of the compressed images given a bit-rate budget. But recently, compressed images are more and more utilized for automatic semantic analysis tasks such as recognition and retrieval. For these tasks, we argue that the optimization target of compression is no longer perceptual quality, but the utility of the compressed images in the given automatic semantic analysis task. Accordingly, we propose to evaluate the quality of the compressed images neither at pixel level nor at perceptual level, but at semantic level. In this paper, we make preliminary efforts towards image semantic quality assessment (ISQA), focusing on the task of optical character recognition (OCR) from compressed images. We propose a full-reference ISQA measure by comparing the features extracted from text regions of original and compressed images. We then propose to integrate the ISQA measure into an image compression scheme. Experimental results show that our proposed ISQA measure is much better than PSNR and SSIM in evaluating the semantic quality of compressed images; accordingly, adopting our ISQA measure to optimize compression for OCR leads to significant bit-rate saving compared to using PSNR or SSIM. Moreover, we perform subjective test about text recognition from compressed images, and observe that our ISQA measure has high consistency with subjective recognizability. Our work explores new dimensions in image quality assessment, and demonstrates promising direction to achieve higher compression ratio for specific semantic analysis tasks.

Autobiographical memory in Parkinson's disease: a retrieval deficit.

Science.gov (United States)

Souchay, Celine; Smith, Sarah Jane

2013-09-01

This study examined the effects of providing cues to facilitate autobiographical memory retrieval in Parkinson's disease. Previous findings have shown that individuals with Parkinson's disease retrieve fewer specific autobiographical memories than older adult controls. These findings are clinically significant since the quality of autobiographical memory is linked to identity and sense of self. In the current study, 16 older adults with Parkinson's disease without dementia and 16 matched older adult controls were given 3 min in which to recall autobiographical memories associated with five different time periods and to give each memory a short title. Participants were later asked to retrieve the memories in three phases: firstly in a free recall phase; secondly in response to general cues (time periods) and finally in response to specific cues (the short titles previously given). The number of memories and the quality of the memory (general or specific) was recorded in each condition. Compared with matched older adult controls, the Parkinson's disease group was impaired in retrieving the memories that they had previously given in the free recall phase and in response to general cues. The performance of the group with Parkinson's disease was only equivalent to the older adults when they retrieved memories in response to self-generated cues. The findings are discussed in relation to theories of autobiographical memory and the neuropsychology of Parkinson's disease. © 2013 The British Psychological Society.

Thermo-fluid dynamic analysis of wet compression process

Energy Technology Data Exchange (ETDEWEB)

Mohan, Abhay; Kim, Heuy Dong [School of Mechanical Engineering, Andong National University, Andong (Korea, Republic of); Chidambaram, Palani Kumar [FMTRC, Daejoo Machinery Co. Ltd., Daegu (Korea, Republic of); Suryan, Abhilash [Dept. of Mechanical Engineering, College of Engineering Trivandrum, Kerala (India)

2016-12-15

Wet compression systems increase the useful power output of a gas turbine by reducing the compressor work through the reduction of air temperature inside the compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PV{sup γ} = constant) are analyzed.

Thermo-fluid dynamic analysis of wet compression process

International Nuclear Information System (INIS)

Mohan, Abhay; Kim, Heuy Dong; Chidambaram, Palani Kumar; Suryan, Abhilash

2016-01-01

Wet compression systems increase the useful power output of a gas turbine by reducing the compressor work through the reduction of air temperature inside the compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PV γ = constant) are analyzed

Safety and safeguards aspects on retrievability: A German study

International Nuclear Information System (INIS)

Biurrun, E.; Engelmann, H.-J.; Brennecke, P.; Kranz, H.

2000-01-01

The article refers shortly to the definition of the term 'retrievability' and shows two different possibilities of retrieval scenarios, their advantages and detriments. The second part lists the Safeguards aspects of retrievability, gives a short outlook on the present German Safeguards Reference Concept in the post-closure phase of a repository in a salt dome and about the results of German studies concerning some proposed Safeguards methods. Furthermore, Planned investigations on Safeguards in the post-closure phase of a repository are mentioned. The third and main part finally describes the results of the German Retrievability Study, which was elaborated in the middle of the nineties by DBE on behalf of the German Federal Ministry of Education, Science, Research and Technology, BMBF, under an R and D contract. (author)

Compressive sensing based ptychography image encryption

Science.gov (United States)

Rawat, Nitin

2015-09-01

A compressive sensing (CS) based ptychography combined with an optical image encryption is proposed. The diffraction pattern is recorded through ptychography technique further compressed by non-uniform sampling via CS framework. The system requires much less encrypted data and provides high security. The diffraction pattern as well as the lesser measurements of the encrypted samples serves as a secret key which make the intruder attacks more difficult. Furthermore, CS shows that the linearly projected few random samples have adequate information for decryption with a dramatic volume reduction. Experimental results validate the feasibility and effectiveness of our proposed technique compared with the existing techniques. The retrieved images do not reveal any information with the original information. In addition, the proposed system can be robust even with partial encryption and under brute-force attacks.

Curvelet-based compressive sensing for InSAR raw data

Science.gov (United States)

Costa, Marcello G.; da Silva Pinho, Marcelo; Fernandes, David

2015-10-01

The aim of this work is to evaluate the compression performance of SAR raw data for interferometry applications collected by airborne from BRADAR (Brazilian SAR System operating in X and P bands) using the new approach based on compressive sensing (CS) to achieve an effective recovery with a good phase preserving. For this framework is desirable a real-time capability, where the collected data can be compressed to reduce onboard storage and bandwidth required for transmission. In the CS theory, a sparse unknown signals can be recovered from a small number of random or pseudo-random measurements by sparsity-promoting nonlinear recovery algorithms. Therefore, the original signal can be significantly reduced. To achieve the sparse representation of SAR signal, was done a curvelet transform. The curvelets constitute a directional frame, which allows an optimal sparse representation of objects with discontinuities along smooth curves as observed in raw data and provides an advanced denoising optimization. For the tests were made available a scene of 8192 x 2048 samples in range and azimuth in X-band with 2 m of resolution. The sparse representation was compressed using low dimension measurements matrices in each curvelet subband. Thus, an iterative CS reconstruction method based on IST (iterative soft/shrinkage threshold) was adjusted to recover the curvelets coefficients and then the original signal. To evaluate the compression performance were computed the compression ratio (CR), signal to noise ratio (SNR), and because the interferometry applications require more reconstruction accuracy the phase parameters like the standard deviation of the phase (PSD) and the mean phase error (MPE) were also computed. Moreover, in the image domain, a single-look complex image was generated to evaluate the compression effects. All results were computed in terms of sparsity analysis to provides an efficient compression and quality recovering appropriated for inSAR applications

Solid phase stability of molybdenum under compression: Sound velocity measurements and first-principles calculations

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xiulu [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang, Sichuan (China); Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, 621010 Mianyang, Sichuan (China); Liu, Zhongli [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang, Sichuan (China); College of Physics and Electric Information, Luoyang Normal University, 471022 Luoyang, Henan (China); Jin, Ke; Xi, Feng; Yu, Yuying; Tan, Ye; Dai, Chengda; Cai, Lingcang [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang, Sichuan (China)

2015-02-07

The high-pressure solid phase stability of molybdenum (Mo) has been the center of a long-standing controversy on its high-pressure melting. In this work, experimental and theoretical researches have been conducted to check its solid phase stability under compression. First, we performed sound velocity measurements from 38 to 160 GPa using the two-stage light gas gun and explosive loading in backward- and forward-impact geometries, along with the high-precision velocity interferometry. From the sound velocities, we found no solid-solid phase transition in Mo before shock melting, which does not support the previous solid-solid phase transition conclusion inferred from the sharp drops of the longitudinal sound velocity [Hixson et al., Phys. Rev. Lett. 62, 637 (1989)]. Then, we searched its structures globally using the multi-algorithm collaborative crystal structure prediction technique combined with the density functional theory. By comparing the enthalpies of body centered cubic structure with those of the metastable structures, we found that bcc is the most stable structure in the range of 0–300 GPa. The present theoretical results together with previous ones greatly support our experimental conclusions.

A Schur complement method for compressible two-phase flow models

International Nuclear Information System (INIS)

Dao, Thu-Huyen; Ndjinga, Michael; Magoules, Frederic

2014-01-01

In this paper, we will report our recent efforts to apply a Schur complement method for nonlinear hyperbolic problems. We use the finite volume method and an implicit version of the Roe approximate Riemann solver. With the interface variable introduced in [4] in the context of single phase flows, we are able to simulate two-fluid models ([12]) with various schemes such as upwind, centered or Rusanov. Moreover, we introduce a scaling strategy to improve the condition number of both the interface system and the local systems. Numerical results for the isentropic two-fluid model and the compressible Navier-Stokes equations in various 2D and 3D configurations and various schemes show that our method is robust and efficient. The scaling strategy considerably reduces the number of GMRES iterations in both interface system and local system resolutions. Comparisons of performances with classical distributed computing with up to 218 processors are also reported. (authors)

Compressive sampling by artificial neural networks for video

Science.gov (United States)

Szu, Harold; Hsu, Charles; Jenkins, Jeffrey; Reinhardt, Kitt

2011-06-01

We describe a smart surveillance strategy for handling novelty changes. Current sensors seem to keep all, redundant or not. The Human Visual System's Hubel-Wiesel (wavelet) edge detection mechanism pays attention to changes in movement, which naturally produce organized sparseness because a stagnant edge is not reported to the brain's visual cortex by retinal neurons. Sparseness is defined as an ordered set of ones (movement or not) relative to zeros that could be pseudo-orthogonal among themselves; then suited for fault tolerant storage and retrieval by means of Associative Memory (AM). The firing is sparse at the change locations. Unlike purely random sparse masks adopted in medical Compressive Sensing, these organized ones have an additional benefit of using the image changes to make retrievable graphical indexes. We coined this organized sparseness as Compressive Sampling; sensing but skipping over redundancy without altering the original image. Thus, we turn illustrate with video the survival tactics which animals that roam the Earth use daily. They acquire nothing but the space-time changes that are important to satisfy specific prey-predator relationships. We have noticed a similarity between the mathematical Compressive Sensing and this biological mechanism used for survival. We have designed a hardware implementation of the Human Visual System's Compressive Sampling scheme. To speed up further, our mixedsignal circuit design of frame differencing is built in on-chip processing hardware. A CMOS trans-conductance amplifier is designed here to generate a linear current output using a pair of differential input voltages from 2 photon detectors for change detection---one for the previous value and the other the subsequent value, ("write" synaptic weight by Hebbian outer products; "read" by inner product & pt. NL threshold) to localize and track the threat targets.

Key Distribution and Changing Key Cryptosystem Based on Phase Retrieval Algorithm and RSA Public-Key Algorithm

Directory of Open Access Journals (Sweden)

Tieyu Zhao

2015-01-01

Full Text Available The optical image encryption has attracted more and more researchers’ attention, and the various encryption schemes have been proposed. In existing optical cryptosystem, the phase functions or images are usually used as the encryption keys, and it is difficult that the traditional public-key algorithm (such as RSA, ECC, etc. is used to complete large numerical key transfer. In this paper, we propose a key distribution scheme based on the phase retrieval algorithm and the RSA public-key algorithm, which solves the problem for the key distribution in optical image encryption system. Furthermore, we also propose a novel image encryption system based on the key distribution principle. In the system, the different keys can be used in every encryption process, which greatly improves the security of the system.

DELIMINATE--a fast and efficient method for loss-less compression of genomic sequences: sequence analysis.

Science.gov (United States)

Mohammed, Monzoorul Haque; Dutta, Anirban; Bose, Tungadri; Chadaram, Sudha; Mande, Sharmila S

2012-10-01

An unprecedented quantity of genome sequence data is currently being generated using next-generation sequencing platforms. This has necessitated the development of novel bioinformatics approaches and algorithms that not only facilitate a meaningful analysis of these data but also aid in efficient compression, storage, retrieval and transmission of huge volumes of the generated data. We present a novel compression algorithm (DELIMINATE) that can rapidly compress genomic sequence data in a loss-less fashion. Validation results indicate relatively higher compression efficiency of DELIMINATE when compared with popular general purpose compression algorithms, namely, gzip, bzip2 and lzma. Linux, Windows and Mac implementations (both 32 and 64-bit) of DELIMINATE are freely available for download at: http://metagenomics.atc.tcs.com/compression/DELIMINATE. sharmila@atc.tcs.com Supplementary data are available at Bioinformatics online.

Venous Leg Ulcers: Effectiveness of new compression therapy/moist ...

African Journals Online (AJOL)

(Cutimed Sorbact) and compression bandages (Comprilan,. Tensoplast) in the initial oedema phase, followed by a compression stocking system delivering 40mmHg (JOBST. UlcerCARE). Due to their high stiffness characteristics, these compression products exert a high working pressure during walking and a comfortably ...

Content Based Retrieval System for Magnetic Resonance Images

International Nuclear Information System (INIS)

Trojachanets, Katarina

2010-01-01

The amount of medical images is continuously increasing as a consequence of the constant growth and development of techniques for digital image acquisition. Manual annotation and description of each image is impractical, expensive and time consuming approach. Moreover, it is an imprecise and insufficient way for describing all information stored in medical images. This induces the necessity for developing efficient image storage, annotation and retrieval systems. Content based image retrieval (CBIR) emerges as an efficient approach for digital image retrieval from large databases. It includes two phases. In the first phase, the visual content of the image is analyzed and the feature extraction process is performed. An appropriate descriptor, namely, feature vector is then associated with each image. These descriptors are used in the second phase, i.e. the retrieval process. With the aim to improve the efficiency and precision of the content based image retrieval systems, feature extraction and automatic image annotation techniques are subject of continuous researches and development. Including the classification techniques in the retrieval process enables automatic image annotation in an existing CBIR system. It contributes to more efficient and easier image organization in the system.Applying content based retrieval in the field of magnetic resonance is a big challenge. Magnetic resonance imaging is an image based diagnostic technique which is widely used in medical environment. According to this, the number of magnetic resonance images is enormously growing. Magnetic resonance images provide plentiful medical information, high resolution and specific nature. Thus, the capability of CBIR systems for image retrieval from large database is of great importance for efficient analysis of this kind of images. The aim of this thesis is to propose content based retrieval system architecture for magnetic resonance images. To provide the system efficiency, feature

Role of Compressibility on Tsunami Propagation

Science.gov (United States)

Abdolali, Ali; Kirby, James T.

2017-12-01

In the present paper, we aim to reduce the discrepancies between tsunami arrival times evaluated from tsunami models and real measurements considering the role of ocean compressibility. We perform qualitative studies to reveal the phase speed reduction rate via a modified version of the Mild Slope Equation for Weakly Compressible fluid (MSEWC) proposed by Sammarco et al. (2013). The model is validated against a 3-D computational model. Physical properties of surface gravity waves are studied and compared with those for waves evaluated from an incompressible flow solver over realistic geometry for 2011 Tohoku-oki event, revealing reduction in phase speed.Plain Language SummarySubmarine earthquakes and submarine mass failures (SMFs), can generate long gravitational waves (or tsunamis) that propagate at the free surface. Tsunami waves can travel long distances and are known for their dramatic effects on coastal areas. Nowadays, numerical models are used to reconstruct the tsunamigenic events for many scientific and socioeconomic aspects i.e. Tsunami Early Warning Systems, inundation mapping, risk and hazard analysis, etc. A number of typically neglected parameters in these models cause discrepancies between model outputs and observations. Most of the tsunami models predict tsunami arrival times at distant stations slightly early in comparison to observations. In this study, we show how ocean compressibility would affect the tsunami wave propagation speed. In this framework, an efficient two-dimensional model equation for the weakly compressible ocean has been developed, validated and tested for simplified and real cases against three dimensional and incompressible solvers. Taking the effect of compressibility, the phase speed of surface gravity waves is reduced compared to that of an incompressible fluid. Then, we used the model for the case of devastating Tohoku-Oki 2011 tsunami event, improving the model accuracy. This study sheds light for future model development

Experimental and numerical study of two-phase flows at the inlet of evaporators in vapour compression cycles

International Nuclear Information System (INIS)

Ahmad, M.

2007-09-01

Maldistribution of liquid-vapour two phase flows causes a significant decrease of the thermal and hydraulic performance of evaporators in thermodynamic vapour compression cycles. A first experimental installation was used to visualize the two phase flow evolution between the expansion valve and the evaporator inlet. A second experimental set-up simulating a compact heat exchanger has been designed to identify the functional and geometrical parameters creating the best distribution of the two phases in the different channels. An analysis and a comprehension of the relation between the geometrical and functional parameters with the flow pattern inside the header and the two phase distribution, has been established. A numerical simulations of a stratified flow and a stratified jet flow have been carried out using two CFD codes: FLUENT and NEPTUNE. In the case of a fragmented jet configuration, a global definition of the interfacial area concentration for a separated phases and dispersed phases flow has been established and a model calculating the fragmented mass fraction has been developed. (author)

Propagation of Shock on NREL Phase VI Wind Turbine Airfoil under Compressible Flow

Directory of Open Access Journals (Sweden)

Mohammad A. Hossain

2013-01-01

Full Text Available The work is focused on numeric analysis of compressible flow around National Renewable Energy Laboratory (NREL phase VI wind turbine blade airfoil S809. Although wind turbine airfoils are low Reynolds number airfoils, a reasonable investigation of compressible flow under extreme condition might be helpful. A subsonic flow (mach no. M=0.8 has been considered for this analysis and the impacts of this flow under seven different angles of attack have been determined. The results show that shock takes place just after the mid span at the top surface and just before the mid span at the bottom surface at zero angle of attack. Slowly the shock waves translate their positions as angle of attack increases. A relative translation of the shock waves in upper and lower face of the airfoil are presented. Variation of Turbulent viscosity ratio and surface Y+ have also been determined. A k-ω SST turbulent model is considered and the commercial CFD code ANSYS FLUENT is used to find the pressure coefficient (Cp as well as the lift (CL and drag coefficients (CD. A graphical comparison of shock propagation has been shown with different angle of attack. Flow separation and stream function are also determined.

Bunch Compression Stability Dependence on RF Parameters

CERN Document Server

Limberg, T

2005-01-01

In present designs for FEL's with high electron peak currents and short bunch lengths, higher harmonic RF systems are often used to optimize the final longitudinal charge distributions. This opens degrees of freedom for the choice of RF phases and amplitudes to achieve the necessary peak current with a reasonable longitudinal bunch shape. It had been found empirically that different working points result in different tolerances for phases and amplitudes. We give an analytical expression for the sensitivity of the compression factor on phase and amplitude jitter for a bunch compression scheme involving two RF systems and two magnetic chicanes as well numerical results for the case of the European XFEL.

Practicing more retrieval routes leads to greater memory retention.

Science.gov (United States)

Zheng, Jun; Zhang, Wei; Li, Tongtong; Liu, Zhaomin; Luo, Liang

2016-09-01

A wealth of research has shown that retrieval practice plays a significant role in improving memory retention. The current study focused on one simple yet rarely examined question: would repeated retrieval using two different retrieval routes or using the same retrieval route twice lead to greater long-term memory retention? Participants elaborately learned 22 Japanese-Chinese translation word pairs using two different mediators. Half an hour after the initial study phase, the participants completed two retrieval sessions using either one mediator (Tm1Tm1) or two different mediators (Tm1Tm2). On the final test, which was performed 1week after the retrieval practice phase, the participants received only the cue with a request to report the mediator (M1 or M2) followed by the target (Experiment 1) or only the mediator (M1 or M2) with a request to report the target (Experiment 2). The results of Experiment 1 indicated that the participants who practiced under the Tm1Tm2 condition exhibited greater target retention than those who practiced under the Tm1Tm1 condition. This difference in performance was due to the significant disadvantage in mediator retrieval and decoding of the unpracticed mediator under the Tm1Tm1 condition. Although mediators were provided to participants on the final test in Experiment 2, decoding of the unpracticed mediators remained less effective than decoding of the practiced mediators. We conclude that practicing multiple retrieval routes leads to greater memory retention than focusing on a single retrieval route. Thus, increasing retrieval variability during repeated retrieval practice indeed significantly improves long-term retention in a delay test. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of compressive stress in TGO layer on impedance spectroscopy from TBC coatings

Energy Technology Data Exchange (ETDEWEB)

Kang, To; Zhang, Jianhai; Yuan, Maodan; Song, Sungjin; Kim, Hakjoon; Kim, Yongseok; Seok, Changsung [Sungkyunkwan Univ., Suwon (Korea, Republic of)

2013-02-15

Impedance spectroscopy is a non destructive evaluation (NDE) method first proposed and developed for evaluating TGO layers with compressive stress inside thermally degraded plasma sprayed thermal barrier coatings (PS TBCs). A bode plot (phase angle ({Dirac_h}) vs. frequency (f)) was used to investigate the TGO layer on electrical responses. In our experimental study, the phase angle of Bode plots is sensitive for detecting TGO layers while applying compressive stress on thermal barrier coatings. It is difficult to detect TGO layers in samples isothermally aged for 100hrs and 200hrs without compressive stress, and substantial change of phase was observed these samples with compressive stress. Also, the frequency shift of the phase angle and change of the phase angle are observed in samples isothermally aged for more than 400hrs.

Thermal reservoir sizing for adiabatic compressed air energy storage

Energy Technology Data Exchange (ETDEWEB)

Kere, Amelie; Goetz, Vincent; Py, Xavier; Olives, Regis; Sadiki, Najim [Perpignan Univ. (France). PROMES CNRS UPR 8521; Mercier-Allart, Eric [EDF R et D, Chatou (France)

2012-07-01

Despite the operation of the two existing industrial facilities to McIntosh (Alabama), and for more than thirty years, Huntorf (Germany), electricity storage in the form of compressed air in underground cavern (CAES) has not seen the development that was expected in the 80s. The efficiency of this form of storage was with the first generation CAES, less than 50%. The evolving context technique can significantly alter this situation. The new generation so-called Adiabatic CAES (A-CAES) is to retrieve the heat produced by the compression via thermal storage, thus eliminating the necessity of gas to burn and would allow consideration efficiency overall energy of the order of 70%. To date, there is no existing installation of A-CAES. Many studies describe the principal and the general working mode of storage systems by adiabatic compression of air. So, efficiencies of different configurations of adiabatic compression process were analyzed. The aim of this paper is to simulate and analyze the performances of a thermal storage reservoir integrated in the system and adapted to the working conditions of a CAES.

Reward eliminates retrieval-induced forgetting.

Science.gov (United States)

Imai, Hisato; Kim, Dongho; Sasaki, Yuka; Watanabe, Takeo

2014-12-02

Although it is well known that reward enhances learning and memory, how extensively such enhancement occurs remains unclear. To address this question, we examined how reward influences retrieval-induced forgetting (RIF) in which the retrieval of a nonpracticed item under the same category as a practiced item is worse than the retrieval of a nonpracticed item outside the category. Subjects were asked to try to encode category-exemplar pairs (e.g., FISH-salmon). Then, they were presented with a category name and a two-letter word stem (e.g., FISH-sa) and were asked to complete an encoded word (retrieval practice). For a correct response, apple juice was given as a reward in the reward condition and a beeping sound was presented in the no-reward condition. Finally, subjects were asked to report whether each exemplar had been presented in the first phase. RIF was replicated in the no-reward condition. However, in the reward condition, RIF was eliminated. These results suggest that reward enhances processing of retrieval of unpracticed members by mechanisms such as spreading activation within the same category, irrespective of whether items were practiced or not.

Information Retrieval and Criticality in Parity-Time-Symmetric Systems.

Science.gov (United States)

Kawabata, Kohei; Ashida, Yuto; Ueda, Masahito

2017-11-10

By investigating information flow between a general parity-time (PT-)symmetric non-Hermitian system and an environment, we find that the complete information retrieval from the environment can be achieved in the PT-unbroken phase, whereas no information can be retrieved in the PT-broken phase. The PT-transition point thus marks the reversible-irreversible criticality of information flow, around which many physical quantities such as the recurrence time and the distinguishability between quantum states exhibit power-law behavior. Moreover, by embedding a PT-symmetric system into a larger Hilbert space so that the entire system obeys unitary dynamics, we reveal that behind the information retrieval lies a hidden entangled partner protected by PT symmetry. Possible experimental situations are also discussed.

A Finite-Volume approach for compressible single- and two-phase flows in flexible pipelines with fluid-structure interaction

Science.gov (United States)

Daude, F.; Galon, P.

2018-06-01

A Finite-Volume scheme for the numerical computations of compressible single- and two-phase flows in flexible pipelines is proposed based on an approximate Godunov-type approach. The spatial discretization is here obtained using the HLLC scheme. In addition, the numerical treatment of abrupt changes in area and network including several pipelines connected at junctions is also considered. The proposed approach is based on the integral form of the governing equations making it possible to tackle general equations of state. A coupled approach for the resolution of fluid-structure interaction of compressible fluid flowing in flexible pipes is considered. The structural problem is solved using Euler-Bernoulli beam finite elements. The present Finite-Volume method is applied to ideal gas and two-phase steam-water based on the Homogeneous Equilibrium Model (HEM) in conjunction with a tabulated equation of state in order to demonstrate its ability to tackle general equations of state. The extensive application of the scheme for both shock tube and other transient flow problems demonstrates its capability to resolve such problems accurately and robustly. Finally, the proposed 1-D fluid-structure interaction model appears to be computationally efficient.

Temperature and pressure dependence of the order parameter fluctuations, conformational compressibility, and the phase diagram of the PEP-PDMS diblock copolymer

DEFF Research Database (Denmark)

Schwahn, D.; Frielinghaus, H.; Mortensen, K.

1996-01-01

The structure factor of a poly(ethylene-propylene)-poly(dimethylsiloxane) diblock copolymer has been measured by small-angle neutron scattering as a function of temperature and pressure. The conformational compressibility exhibits a pronounced maximum at the order-disorder phase transition. The p...

The 1995 Science Information Management and Data Compression Workshop

Science.gov (United States)

Tilton, James C. (Editor)

1995-01-01

This document is the proceedings from the 'Science Information Management and Data Compression Workshop,' which was held on October 26-27, 1995, at the NASA Goddard Space Flight Center, Greenbelt, Maryland. The Workshop explored promising computational approaches for handling the collection, ingestion, archival, and retrieval of large quantities of data in future Earth and space science missions. It consisted of fourteen presentations covering a range of information management and data compression approaches that are being or have been integrated into actual or prototypical Earth or space science data information systems, or that hold promise for such an application. The Workshop was organized by James C. Tilton and Robert F. Cromp of the NASA Goddard Space Flight Center.

Phase behavior of poly(dimethylsiloxane)-poly(ethylene oxide) amphiphilic block and graft copolymers in compressed carbon dioxide

International Nuclear Information System (INIS)

Stoychev, Ivan; Peters, Felix; Kleiner, Matthias; Sadowski, Gabriele; Clerc, Sebastien; Ganachaud, Francois; Chirat, Mathieu; Lacroix-Desmazes, Patrick; Fournel, Bruno

2012-01-01

The phase behavior of triblock and graft-type poly(dimethylsiloxane) (PDMS)-poly(ethylene oxide) (PEO) copolymer surfactants has been investigated in compressed carbon dioxide (CO 2 ). For this purpose, cloud-point pressures have been measured in the pressure and temperature range from P=10 to 40 MPa and from T= 293 to 338 K. The Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EoS) has been applied to model the experimental data in order to better understand the influence of the structure of the copolymers on the phase behavior of the system. The pure-component parameters for PDMS have been fitted originally to PDMS/n-pentane system. These parameters are successfully applied for PDMS in CO 2 by adjusting a temperature-dependent binary interaction parameter. The phase behavior of the triblock copolymers was successfully predicted by PC-SAFT. In contrast, the phase behavior of the graft copolymers was difficult to predict accurately at this stage. (authors)

A sharp interface method for compressible liquid–vapor flow with phase transition and surface tension

Energy Technology Data Exchange (ETDEWEB)

Fechter, Stefan, E-mail: stefan.fechter@iag.uni-stuttgart.de [Institut für Aerodynamik und Gasdynamik, Universität Stuttgart, Pfaffenwaldring 21, 70569 Stuttgart (Germany); Munz, Claus-Dieter, E-mail: munz@iag.uni-stuttgart.de [Institut für Aerodynamik und Gasdynamik, Universität Stuttgart, Pfaffenwaldring 21, 70569 Stuttgart (Germany); Rohde, Christian, E-mail: Christian.Rohde@mathematik.uni-stuttgart.de [Institut für Angewandte Analysis und Numerische Simulation, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart (Germany); Zeiler, Christoph, E-mail: Christoph.Zeiler@mathematik.uni-stuttgart.de [Institut für Angewandte Analysis und Numerische Simulation, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart (Germany)

2017-05-01

The numerical approximation of non-isothermal liquid–vapor flow within the compressible regime is a difficult task because complex physical effects at the phase interfaces can govern the global flow behavior. We present a sharp interface approach which treats the interface as a shock-wave like discontinuity. Any mixing of fluid phases is avoided by using the flow solver in the bulk regions only, and a ghost-fluid approach close to the interface. The coupling states for the numerical solution in the bulk regions are determined by the solution of local two-phase Riemann problems across the interface. The Riemann solution accounts for the relevant physics by enforcing appropriate jump conditions at the phase boundary. A wide variety of interface effects can be handled in a thermodynamically consistent way. This includes surface tension or mass/energy transfer by phase transition. Moreover, the local normal speed of the interface, which is needed to calculate the time evolution of the interface, is given by the Riemann solution. The interface tracking itself is based on a level-set method. The focus in this paper is the description of the two-phase Riemann solver and its usage within the sharp interface approach. One-dimensional problems are selected to validate the approach. Finally, the three-dimensional simulation of a wobbling droplet and a shock droplet interaction in two dimensions are shown. In both problems phase transition and surface tension determine the global bulk behavior.

Three-dimensional range data compression using computer graphics rendering pipeline.

Science.gov (United States)

Zhang, Song

2012-06-20

This paper presents the idea of naturally encoding three-dimensional (3D) range data into regular two-dimensional (2D) images utilizing computer graphics rendering pipeline. The computer graphics pipeline provides a means to sample 3D geometry data into regular 2D images, and also to retrieve the depth information for each sampled pixel. The depth information for each pixel is further encoded into red, green, and blue color channels of regular 2D images. The 2D images can further be compressed with existing 2D image compression techniques. By this novel means, 3D geometry data obtained by 3D range scanners can be instantaneously compressed into 2D images, providing a novel way of storing 3D range data into its 2D counterparts. We will present experimental results to verify the performance of this proposed technique.

Restoration of the efferent phase of the sneeze reflex after regression of an Arnold-Chiari malformation with compression of the medulla oblongata.

Science.gov (United States)

Songu, Murat; Can, Nazan; Gelal, Fazil

2013-01-01

The precise location of the sneeze center in the human brain has not been definitively identified. The aim of this report is to contribute to the effort to detect its location. We report the case of a 13-year-old boy who presented to our outpatient clinic for evaluation of an inability to sneeze. In an attempt to trigger the afferent (nasal) phase of the sneeze reflex, we first applied a cotton swab and later a silver nitrate stick to the patient's nasal mucosa. Once that was accomplished, we observed that the patient could not complete the efferent (expiratory) phase of the sneeze reflex, and thus he did not sneeze. Cranial magnetic resonance imaging (MRI) revealed that his cerebellar tonsils extended approximately 10 mm inferiorly through the foramen magnum, which represented a type I Arnold-Chiari malformation. The tonsils were noted to have compressed the posterolateral portion of the medulla oblongata. At follow-up 21 months later, we noted that the patient was able to sneeze spontaneously as well as with nasal stimulation. Repeat MRI revealed that the Arnold-Chiari malformation had undergone a spontaneous partial regression, which resulted in relief of the compression of the medulla oblongata. We believe that the patient's earlier inability to sneeze might have been attributable to the compression of the medulla oblongata by the cerebellar tonsils and that the site of the compression might represent the location of his sneeze center.

Wave Optics Based LEO-LEO Radio Occultation Retrieval

DEFF Research Database (Denmark)

von Benzon, Hans-Henrik; Høeg, Per

2016-01-01

of the atmospheric products such as the correct water vapor content in the atmosphere. These limitations can be overcome when a proper selected range of high frequency waves are used to probe the atmosphere. Probing frequencies close to the absorption line of water vapor have been included, thus allowing...... the retrieval of the water vapor content. Selecting the correct probing frequencies would make it possible to retrieve other information such as the content of ozone. The retrieval is performed through a number of processing steps which are based on the Full Spectrum Inversion (FSI) technique. The retrieval...... optics based retrieval chain is used on a number of examples and the retrieved atmospheric parameters are compared to the parameters from a global ECMWF analysis model. This model is used in a forward propagator that simulates the electromagnetic field amplitudes and phases at the receiver on board...

Morphology of the boron-rich phase along columnar grain boundary and its effect on the compression crack of Fe-6.5Si-0.05B alloy

International Nuclear Information System (INIS)

Fu Huadong; Zhang Zhihao; Yang Qiang; Xie Jianxin

2011-01-01

Research highlights: → Three morphologies of alloy phases were observed under different conditions. → Three different morphologies were thick-strip, fish-bone like and thin-strip. → These phases were all with enrichment of boron and dilution of silicon. → Three morphologies of alloy phases had different influences on mechanical property. - Abstract: The morphology of precipitated phases along Fe-6.5Si-0.05B columnar grain boundary and its effect on the initiation and propagation of compression cracks were investigated. Under the present experimental condition, alloy phases along the grain boundary exhibited three different morphologies, i.e., thick-strip, fish-bone like and thin-strip. These phases were all with enrichment of boron and dilution of silicon. The grain boundary with dendrite growth mode was apt to generate the thick-strip and fish-bone like phases, while the boundary with cellular growth mode was easy to form the thin-strip phase. The thick-strip phase was favorable to form 'weak plane' containing numerous micropores, which ultimately led to intergranular cracks. The fish-bone like phase was one of the main crack sources under the compression processing and easily caused transgranular cracks. The thin-strip phase enhanced the bond strength of the grain boundary and detained the crack propagation.

Team Size and Stretching-Exercise Effects on Simulated Chest Compression Performance and Exertion

Directory of Open Access Journals (Sweden)

Jessica C. Schoen

2017-09-01

Full Text Available Introduction: Investigators conducted a prospective experimental study to evaluate the effect of team size and recovery exercises on individual providers’ compression quality and exertion. Investigators hypothesized that 1 larger teams would perform higher quality compressions with less exertion per provider when compared to smaller teams; and 2 brief stretching and breathing exercises during rest periods would sustain compressor performance and mitigate fatigue. Methods: In Phase I, a volunteer cohort of pre-clinical medical students performed four minutes of continuous compressions on a Resusci-Anne manikin to gauge the spectrum of compressor performance in the subject population. Compression rate, depth, and chest recoil were measured. In Phase II, the highest-performing Phase I subjects were placed into 2-, 3-, and/or 4-compressor teams; 2-compressor teams were assigned either to control group (no recovery exercises or intervention group (recovery exercises during rest. All Phase II teams participated in 20-minute simulations with compressor rotation every two minutes. Investigators recorded compression quality and real-time heart rate data, and calculated caloric expenditure from contact heart rate monitor measurements using validated physiologic formulas. Results: Phase I subjects delivered compressions that were 24.9% (IQR1–3: [0.5%–74.1%] correct with a median rate of 112.0 (IQR1–3: [103.5–124.9] compressions per minute and depth of 47.2 (IQR1–3: [35.7–55.2] mm. In their first rotations, all Phase II subjects delivered compressions of similar quality and correctness (p=0.09. Bivariate analyses of 2-, 3-, and 4-compressor teams’ subject compression characteristics by subsequent rotation did not identify significant differences within or across teams. On multivariate analyses, only subjects in 2-compressor teams exhibited significantly lower compression rates (control subjects; p<0.01, diminished chest release (intervention

Numerical and theoretical aspects of the modelling of compressible two-phase flow by interface capture methods

International Nuclear Information System (INIS)

Kokh, S.

2001-01-01

This research thesis reports the development of a numerical direct simulation of compressible two-phase flows by using interface capturing methods. These techniques are based on the use of an Eulerian fixed grid to describe flow variables as well as the interface between fluids. The author first recalls conventional interface capturing methods and makes the distinction between those based on discontinuous colour functions and those based on level set functions. The approach is then extended to a five equation model to allow the largest as possible choice of state equations for the fluids. Three variants are developed. A solver inspired by the Roe scheme is developed for one of them. These interface capturing methods are then refined, more particularly for problems of numerical diffusion at the interface. A last part addresses the study of dynamic phase change. Non-conventional thermodynamics tools are used to study the structures of an interface which performs phase transition [fr

Two divergent paths: compression vs. non-compression in deep venous thrombosis and post thrombotic syndrome

Directory of Open Access Journals (Sweden)

Eduardo Simões Da Matta

Full Text Available Abstract Use of compression therapy to reduce the incidence of postthrombotic syndrome among patients with deep venous thrombosis is a controversial subject and there is no consensus on use of elastic versus inelastic compression, or on the levels and duration of compression. Inelastic devices with a higher static stiffness index, combine relatively small and comfortable pressure at rest with pressure while standing strong enough to restore the “valve mechanism” generated by plantar flexion and dorsiflexion of the foot. Since the static stiffness index is dependent on the rigidity of the compression system and the muscle strength within the bandaged area, improvement of muscle mass with muscle-strengthening programs and endurance training should be encouraged. Therefore, in the acute phase of deep venous thrombosis events, anticoagulation combined with inelastic compression therapy can reduce the extension of the thrombus. Notwithstanding, prospective studies evaluating the effectiveness of inelastic therapy in deep venous thrombosis and post-thrombotic syndrome are needed.

Inter frame motion estimation and its application to image sequence compression: an introduction

International Nuclear Information System (INIS)

Cremy, C.

1996-01-01

With the constant development of new communication technologies like, digital TV, teleconference, and the development of image analysis applications, there is a growing volume of data to manage. Compression techniques are required for the transmission and storage of these data. Dealing with original images would require the use of expansive high bandwidth communication devices and huge storage media. Image sequence compression can be achieved by means of interframe estimation that consists in retrieving redundant information relative to zones where there is little motion between two frames. This paper is an introduction to some motion estimation techniques like gradient techniques, pel-recursive, block-matching, and its application to image sequence compression. (Author) 17 refs

On the determination of adiabatic compressibility, isoentropy coefficient and other properties of two-phase media

International Nuclear Information System (INIS)

Aleshin, V.S.

1980-01-01

Presented are calculated dependences for adiabatic compressibility, isoentropy coefficient and thermodynamic sound velocity of a two-phase media with homogeneous disperse structure being in a state of equilibrium. The character of the change of the values mentioned for vapor water media at the change of vapor mass composition in the mixture from zero to 1 is shown. Comparison of the calculated data as to dependences obtained with the experimental ones for critical regimes of vapor-water flow outflow through short and long cylindrical channels with sharp entrance rims. The calculation error does not exceed approximately 12%. Analysis of the results obtained showed that at outflow through short channels of metastable vapor liquid flow the main characteristics, like at outflow through long channels, are determined by the pressure in the exit cross section, mass vapor content and specific volume of the mixture, which are calculated with account for real overheating of the liquid to the exit cross section. At critical regime of outflow through the very long channels, when one can not neglect hydraulic resistance in the channel and the process is not isoentropic, the pressure and mass vapor content in the exit cross section also unambiguously determine the value of adiabatic compressibility of two-phase media, sound velocity and isoentropy coefficient in the cross section. Conclusion is made that the dependences obtained can be used with sufficient for practical purposes accuracy when solving different engineering problems, as well as for the calculations of the mixture consumption at flow of the reactor contours NAI with WWR

Prediction of the compression ratio for municipal solid waste using decision tree.

Science.gov (United States)

Heshmati R, Ali Akbar; Mokhtari, Maryam; Shakiba Rad, Saeed

2014-01-01

The compression ratio of municipal solid waste (MSW) is an essential parameter for evaluation of waste settlement and landfill design. However, no appropriate model has been proposed to estimate the waste compression ratio so far. In this study, a decision tree method was utilized to predict the waste compression ratio (C'c). The tree was constructed using Quinlan's M5 algorithm. A reliable database retrieved from the literature was used to develop a practical model that relates C'c to waste composition and properties, including dry density, dry weight water content, and percentage of biodegradable organic waste using the decision tree method. The performance of the developed model was examined in terms of different statistical criteria, including correlation coefficient, root mean squared error, mean absolute error and mean bias error, recommended by researchers. The obtained results demonstrate that the suggested model is able to evaluate the compression ratio of MSW effectively.

Compressive Phase Contrast Tomography

International Nuclear Information System (INIS)

Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

2010-01-01

When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

NON-COHESIVE SOILS’ COMPRESSIBILITY AND UNEVEN GRAIN-SIZE DISTRIBUTION RELATION

Directory of Open Access Journals (Sweden)

Anatoliy Mirnyy

2016-03-01

Full Text Available This paper presents the results of laboratory investigation of soil compression phases with consideration of various granulometric composition. Materials and Methods Experimental soil box with microscale video recording for compression phases studies is described. Photo and video materials showing the differences of microscale particle movements were obtained for non-cohesive soils with different grain-size distribution. Results The analysis of the compression tests results and elastic and plastic deformations separation allows identifying each compression phase. It is shown, that soil density is correlating with deformability parameters only for the same grain-size distribution. Basing on the test results the authors suggest that compaction ratio is not sufficient for deformability estimating without grain-size distribution taken into account. Discussion and Conclusions Considering grain-size distribution allows refining technological requirements for artificial soil structures, backfills, and sand beds. Further studies could be used for developing standard documents, SP45.13330.2012 in particular.

Nonlinear propagation analysis of few-optical-cycle pulses for subfemtosecond compression and carrier envelope phase effect

International Nuclear Information System (INIS)

Mizuta, Yo; Nagasawa, Minoru; Ohtani, Morimasa; Yamashita, Mikio

2005-01-01

A numerical approach called Fourier direct method (FDM) is applied to nonlinear propagation of optical pulses with the central wavelength 800 nm, the width 2.67-12.00 fs, and the peak power 25-6870 kW in a fused-silica fiber. Bidirectional propagation, delayed Raman response, nonlinear dispersion (self-steepening, core dispersion), as well as correct linear dispersion are incorporated into 'bidirectional propagation equations' which are derived directly from Maxwell's equations. These equations are solved for forward and backward waves, instead of the electric-field envelope as in the nonlinear Schroedinger equation (NLSE). They are integrated as multidimensional simultaneous evolution equations evolved in space. We investigate, both theoretically and numerically, the validity and the limitation of assumptions and approximations used for deriving the NLSE. Also, the accuracy and the efficiency of the FDM are compared quantitatively with those of the finite-difference time-domain numerical approach. The time-domain size 500 fs and the number of grid points in time 2048 are chosen to investigate numerically intensity spectra, spectral phases, and temporal electric-field profiles up to the propagation distance 1.0 mm. On the intensity spectrum of a few-optical-cycle pulses, the self-steepening, core dispersion, and the delayed Raman response appear as dominant, middle, and slight effects, respectively. The delayed Raman response and the core dispersion reduce the effective nonlinearity. Correct linear dispersion is important since it affects the intensity spectrum sensitively. For the compression of femtosecond optical pulses by the complete phase compensation, the shortness and the pulse quality of compressed pulses are remarkably improved by the intense initial peak power rather than by the short initial pulse width or by the propagation distance longer than 0.1 mm. They will be compressed as short as 0.3 fs below the damage threshold of fused-silica fiber 6 MW. It

Design and development of a content-based medical image retrieval system for spine vertebrae irregularity.

Science.gov (United States)

Mustapha, Aouache; Hussain, Aini; Samad, Salina Abdul; Zulkifley, Mohd Asyraf; Diyana Wan Zaki, Wan Mimi; Hamid, Hamzaini Abdul

2015-01-16

Content-based medical image retrieval (CBMIR) system enables medical practitioners to perform fast diagnosis through quantitative assessment of the visual information of various modalities. In this paper, a more robust CBMIR system that deals with both cervical and lumbar vertebrae irregularity is afforded. It comprises three main phases, namely modelling, indexing and retrieval of the vertebrae image. The main tasks in the modelling phase are to improve and enhance the visibility of the x-ray image for better segmentation results using active shape model (ASM). The segmented vertebral fractures are then characterized in the indexing phase using region-based fracture characterization (RB-FC) and contour-based fracture characterization (CB-FC). Upon a query, the characterized features are compared to the query image. Effectiveness of the retrieval phase is determined by its retrieval, thus, we propose an integration of the predictor model based cross validation neural network (PMCVNN) and similarity matching (SM) in this stage. The PMCVNN task is to identify the correct vertebral irregularity class through classification allowing the SM process to be more efficient. Retrieval performance between the proposed and the standard retrieval architectures are then compared using retrieval precision (Pr@M) and average group score (AGS) measures. Experimental results show that the new integrated retrieval architecture performs better than those of the standard CBMIR architecture with retrieval results of cervical (AGS > 87%) and lumbar (AGS > 82%) datasets. The proposed CBMIR architecture shows encouraging results with high Pr@M accuracy. As a result, images from the same visualization class are returned for further used by the medical personnel.

DNABIT Compress - Genome compression algorithm.

Science.gov (United States)

Rajarajeswari, Pothuraju; Apparao, Allam

2011-01-22

Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, "DNABIT Compress" for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our proposed algorithm achieves the best compression ratio for DNA sequences for larger genome. Significantly better compression results show that "DNABIT Compress" algorithm is the best among the remaining compression algorithms. While achieving the best compression ratios for DNA sequences (Genomes),our new DNABIT Compress algorithm significantly improves the running time of all previous DNA compression programs. Assigning binary bits (Unique BIT CODE) for (Exact Repeats, Reverse Repeats) fragments of DNA sequence is also a unique concept introduced in this algorithm for the first time in DNA compression. This proposed new algorithm could achieve the best compression ratio as much as 1.58 bits/bases where the existing best methods could not achieve a ratio less than 1.72 bits/bases.

Bilateral saccadic eye movements and tactile stimulation, but not auditory stimulation, enhance memory retrieval

NARCIS (Netherlands)

Nieuwenhuis, S.; Elzinga, B.M.; Ras, P.H.; Berends, F.; Duijs, P.; Samara, Z.; Slagter, H.A.

2013-01-01

Recent research has shown superior memory retrieval when participants make a series of horizontal saccadic eye movements between the memory encoding phase and the retrieval phase compared to participants who do not move their eyes or move their eyes vertically. It has been hypothesized that the

Wire-wrap bundle compression-characteristics study. Phase I

International Nuclear Information System (INIS)

Chertock, A.J.

1974-06-01

An analytical computer comparison was made of the compression characteristics of proposed wire-wrap bundles. The study included analysis of 7- and 37-rod straight-start bundles (base configuration), and softened 37-rod configurations. The softened configurations analyzed were: straight-start with distributed wireless fuel rods, and the staggered wire-wrap start angles of 0 0 -30 0 -60 0 and 0 0 -45 0 -90 0 . The compression of the bundle simulates the bundle-to-channel interference at end-of-life conditions at which high differential swelling between the channel and bundle has been predicted. The computer results do not include the so-called dispersion effects. The effects of other variables such as pitch length, creep, axial variations in swelling, and degree of swelling were not studied. These analytic studies give an indication of trends only. No credence should be given to specific quantitative load or deflection results quoted in this report

Experimental investigation of dynamic compression and spallation of Cerium at pressures up to 6 GPa

Science.gov (United States)

Zubareva, A. N.; Kolesnikov, S. A.; Utkin, A. V.

2014-05-01

In this study the experiments on one-dimensional dynamic compression of Cerium (Ce) samples to pressures of 0.5 to 6 GPa using various types of explosively driven generators were conducted. VISAR laser velocimeter was used to obtain Ce free surface velocity profiles. The isentropic compression wave was registered for γ-phase of Ce at pressures lower than 0.76 GPa that corresponds to γ-α phase transition pressure in Ce. Shock rarefaction waves were also registered in several experiments. Both observations were the result of the anomalous compressibility of γ-phase of Ce. On the basis of our experimental results the compression isentrope of Ce γ-phase was constructed. Its comparison with volumetric compression curves allowed to estimate the magnitude of shear stress at dynamic compression conditions for Ce. Spall strength measurements were also conducted for several samples. They showed a strong dependence of the spall strength of Ce on the strain rate.

Experimental investigation of dynamic compression and spallation of cerium at pressures up to 6 GPa

International Nuclear Information System (INIS)

Zubareva, A N; Kolesnikov, S A; Utkin, A V

2014-01-01

In this study the experiments on one-dimensional dynamic compression of Cerium (Ce) samples to pressures of 0.5 to 6 GPa using various types of explosively driven generators were conducted. VISAR laser velocimeter was used to obtain Ce free surface velocity profiles. The isentropic compression wave was registered for γ-phase of Ce at pressures lower than 0.76 GPa that corresponds to γ-α phase transition pressure in Ce. Shock rarefaction waves were also registered in several experiments. Both observations were the result of the anomalous compressibility of γ-phase of Ce. On the basis of our experimental results the compression isentrope of Ce γ-phase was constructed. Its comparison with volumetric compression curves allowed to estimate the magnitude of shear stress at dynamic compression conditions for Ce. Spall strength measurements were also conducted for several samples. They showed a strong dependence of the spall strength of Ce on the strain rate.

Compressing a spinodal surface at fixed area: bijels in a centrifuge.

Science.gov (United States)

Rumble, Katherine A; Thijssen, Job H J; Schofield, Andrew B; Clegg, Paul S

2016-05-11

Bicontinuous interfacially jammed emulsion gels (bijels) are solid-stabilised emulsions with two inter-penetrating continuous phases. Employing the method of centrifugal compression we find that macroscopically the bijel yields at relatively low angular acceleration. Both continuous phases escape from the top of the structure, making any compression immediately irreversible. Microscopically, the bijel becomes anisotropic with the domains aligned perpendicular to the compression direction which inhibits further liquid expulsion; this contrasts strongly with the sedimentation behaviour of colloidal gels. The original structure can, however, be preserved close to the top of the sample and thus the change to an anisotropic structure suggests internal yielding. Any air bubbles trapped in the bijel are found to aid compression by forming channels aligned parallel to the compression direction which provide a route for liquid to escape.

MP3 compression of Doppler ultrasound signals.

Science.gov (United States)

Poepping, Tamie L; Gill, Jeremy; Fenster, Aaron; Holdsworth, David W

2003-01-01

The effect of lossy, MP3 compression on spectral parameters derived from Doppler ultrasound (US) signals was investigated. Compression was tested on signals acquired from two sources: 1. phase quadrature and 2. stereo audio directional output. A total of 11, 10-s acquisitions of Doppler US signal were collected from each source at three sites in a flow phantom. Doppler signals were digitized at 44.1 kHz and compressed using four grades of MP3 compression (in kilobits per second, kbps; compression ratios in brackets): 1400 kbps (uncompressed), 128 kbps (11:1), 64 kbps (22:1) and 32 kbps (44:1). Doppler spectra were characterized by peak velocity, mean velocity, spectral width, integrated power and ratio of spectral power between negative and positive velocities. The results suggest that MP3 compression on digital Doppler US signals is feasible at 128 kbps, with a resulting 11:1 compression ratio, without compromising clinically relevant information. Higher compression ratios led to significant differences for both signal sources when compared with the uncompressed signals. Copyright 2003 World Federation for Ultrasound in Medicine & Biology

Structural transitions and hysteresis in clump- and stripe-forming systems under dynamic compression

International Nuclear Information System (INIS)

McDermott, Danielle; Reichhardt, Charles

2016-01-01

In using numerical simulations, we study the dynamical evolution of particles interacting via competing long-range repulsion and short-range attraction in two dimensions. The particles are compressed using a time-dependent quasi-one dimensional trough potential that controls the local density, causing the system to undergo a series of structural phase transitions from a low density clump lattice to stripes, voids, and a high density uniform state. The compression proceeds via slow elastic motion that is interrupted with avalanche-like bursts of activity as the system collapses to progressively higher densities via plastic rearrangements. The plastic events vary in magnitude from small rearrangements of particles, including the formation of quadrupole-like defects, to large-scale vorticity and structural phase transitions. In the dense uniform phase, the system compresses through row reduction transitions mediated by a disorder-order process. We also characterize the rearrangement events by measuring changes in the potential energy, the fraction of sixfold coordinated particles, the local density, and the velocity distribution. At high confinements, we find power law scaling of the velocity distribution during row reduction transitions. We observe hysteresis under a reversal of the compression when relatively few plastic rearrangements occur. The decompressing system exhibits distinct phase morphologies, and the phase transitions occur at lower compression forces as the system expands compared to when it is compressed.

Treatment of Proper Name Retrieval Deficits in an Individual with Temporal Lobe Epilepsy

Science.gov (United States)

Minkina, Irene; Ojemann, Jeffrey G.; Grabowski, Thomas J.; Silkes, JoAnn P.; Phatak, Vaishali; Kendall, Diane L.

2013-01-01

Purpose: Studies investigating language deficits in individuals with left temporal-lobe epilepsy have consistently demonstrated impairments in proper name retrieval. The aim of this Phase I rehabilitation study was to investigate the effects of a linguistically distributed word retrieval treatment on proper name retrieval in an individual with…

Video compression and DICOM proxies for remote viewing of DICOM images

Science.gov (United States)

Khorasani, Elahe; Sheinin, Vadim; Paulovicks, Brent; Jagmohan, Ashish

2009-02-01

Digital medical images are rapidly growing in size and volume. A typical study includes multiple image "slices." These images have a special format and a communication protocol referred to as DICOM (Digital Imaging Communications in Medicine). Storing, retrieving, and viewing these images are handled by DICOM-enabled systems. DICOM images are stored in central repository servers called PACS (Picture Archival and Communication Systems). Remote viewing stations are DICOM-enabled applications that can query the PACS servers and retrieve the DICOM images for viewing. Modern medical images are quite large, reaching as much as 1 GB per file. When the viewing station is connected to the PACS server via a high-bandwidth local LAN, downloading of the images is relatively efficient and does not cause significant wasted time for physicians. Problems arise when the viewing station is located in a remote facility that has a low-bandwidth link to the PACS server. If the link between the PACS and remote facility is in the range of 1 Mbit/sec, downloading medical images is very slow. To overcome this problem, medical images are compressed to reduce the size for transmission. This paper describes a method of compression that maintains diagnostic quality of images while significantly reducing the volume to be transmitted, without any change to the existing PACS servers and viewer software, and without requiring any change in the way doctors retrieve and view images today.

Preliminary time-phased TWRS process model results

International Nuclear Information System (INIS)

Orme, R.M.

1995-01-01

This report documents the first phase of efforts to model the retrieval and processing of Hanford tank waste within the constraints of an assumed tank farm configuration. This time-phased approach simulates a first try at a retrieval sequence, the batching of waste through retrieval facilities, the batching of retrieved waste through enhanced sludge washing, the batching of liquids through pretreatment and low-level waste (LLW) vitrification, and the batching of pretreated solids through high-level waste (HLW) vitrification. The results reflect the outcome of an assumed retrieval sequence that has not been tailored with respect to accepted measures of performance. The batch data, composition variability, and final waste volume projects in this report should be regarded as tentative. Nevertheless, the results provide interesting insights into time-phased processing of the tank waste. Inspection of the composition variability, for example, suggests modifications to the retrieval sequence that will further improve the uniformity of feed to the vitrification facilities. This model will be a valuable tool for evaluating suggested retrieval sequences and establishing a time-phased processing baseline. An official recommendation on tank retrieval sequence will be made in September, 1995

Bilateral Saccadic Eye Movements and Tactile Stimulation, but Not Auditory Stimulation, Enhance Memory Retrieval

Science.gov (United States)

Nieuwenhuis, Sander; Elzinga, Bernet M.; Ras, Priscilla H.; Berends, Floris; Duijs, Peter; Samara, Zoe; Slagter, Heleen A.

2013-01-01

Recent research has shown superior memory retrieval when participants make a series of horizontal saccadic eye movements between the memory encoding phase and the retrieval phase compared to participants who do not move their eyes or move their eyes vertically. It has been hypothesized that the rapidly alternating activation of the two hemispheres…

Level of recall, retrieval speed, and variability on the Cued-Recall Retrieval Speed Task (CRRST) in individuals with amnestic mild cognitive impairment.

Science.gov (United States)

Ramratan, Wendy S; Rabin, Laura A; Wang, Cuiling; Zimmerman, Molly E; Katz, Mindy J; Lipton, Richard B; Buschke, Herman

2012-03-01

Individuals with amnestic mild cognitive impairment (aMCI) show deficits on traditional episodic memory tasks and reductions in speed of performance on reaction time tasks. We present results on a novel task, the Cued-Recall Retrieval Speed Task (CRRST), designed to simultaneously measure level and speed of retrieval. A total of 390 older adults (mean age, 80.2 years), learned 16 words based on corresponding categorical cues. In the retrieval phase, we measured accuracy (% correct) and retrieval speed/reaction time (RT; time from cue presentation to voice onset of a correct response) across 6 trials. Compared to healthy elderly adults (HEA, n = 303), those with aMCI (n = 87) exhibited poorer performance in retrieval speed (difference = -0.13; p cued-learning and processing speed variability may facilitate early detection of dementia in at-risk older adults.

Modeling of the anode of a liquid-feed DMFC: Inhomogeneous compression effects and two-phase transport phenomena

Science.gov (United States)

García-Salaberri, Pablo A.; Vera, Marcos; Iglesias, Immaculada

2014-01-01

An isothermal two-phase 2D/1D across-the-channel model for the anode of a liquid-feed Direct Methanol Fuel Cell (DMFC) is presented. The model takes into account the effects of the inhomogeneous assembly compression of the Gas Diffusion Layer (GDL), including the spatial variations of porosity, diffusivity, permeability, capillary pressure, and electrical conductivity. The effective anisotropic properties of the GDL are evaluated from empirical data reported in the literature corresponding to Toray carbon paper TGP-H series. Multiphase transport is modeled according to the classical theory of porous media (two-fluid model), considering the effect of non-equilibrium evaporation and condensation of methanol and water. The numerical results evidence that the hydrophobic Leverett J-function approach is physically inconsistent to describe capillary transport in the anode of a DMFC when assembly compression effects are considered. In contrast, more realistic results are obtained when GDL-specific capillary pressure curves reflecting the mixed-wettability characteristics of GDLs are taken into account. The gas coverage factor at the GDL/channel interface also exhibits a strong influence on the gas-void fraction distribution in the GDL, which in turn depends on the relative importance between the capillary resistance induced by the inhomogeneous compression, Rc(∝ ∂pc / ∂ ε) , and the capillary diffusivity, Dbarc(∝ ∂pc / ∂ s) .

Processing Depth and Episodic Retrieval: an fMRI study

OpenAIRE

Beratis, Ion

2010-01-01

Background. According to the reinstatement theory that stems from the transfer appropriate processing (TAP) and the encoding specificity principles, episodic retrieval involves reactivation of processes and, therefore, of brain regions that were active during encoding. Hence, if two encoding conditions engage different cognitive operations, qualitative differences are expected also to be present at the retrieval phase. Functional neuroimaging applications have detected qualitative differences...

TMS evidence for a selective role of the precuneus in source memory retrieval.

Science.gov (United States)

Bonnì, Sonia; Veniero, Domenica; Mastropasqua, Chiara; Ponzo, Viviana; Caltagirone, Carlo; Bozzali, Marco; Koch, Giacomo

2015-04-01

The posteromedial cortex including the precuneus (PC) is thought to be involved in episodic memory retrieval. Here we used continuous theta burst stimulation (cTBS) to disentangle the role of the precuneus in the recognition memory process in a sample of healthy subjects. During the encoding phase, subjects were presented with a series of colored pictures. Afterwards, during the retrieval phase, all previously presented items and a sample of new pictures were presented in black, and subjects were asked to indicate whether each item was new or old, and in the latter case to indicate the associated color. cTBS was delivered over PC, posterior parietal cortex (PPC) and vertex before the retrieval phase. The data were analyzed in terms of hits, false alarms, source errors and omissions. cTBS over the precuneus, but not over the PPC or the vertex, induced a selective decrease in source memory errors, indicating an improvement in context retrieval. All the other accuracy measurements were unchanged. These findings suggest a direct implication of the precuneus in successful context-dependent retrieval. Copyright © 2015 Elsevier B.V. All rights reserved.

Cascade and intermittency model for turbulent compressible self-gravitating matter and self-binding phase-space density fluctuations

International Nuclear Information System (INIS)

Biglari, H.; Diamond, P.H.

1988-01-01

A simple physical model which describes the dynamics of turbulence and the spectrum of density fluctuations in compressible, self-gravitating matter and self-binding, phase-space density fluctuations is presented. The two systems are analogous to each other in that each tends to self-organize into hierarchical structures via the mechanism of Jeans collapse. The model, the essential physical ingredient of which is a cascade constrained by the physical requirement of quasivirialization, is shown to exhibit interesting geometric properties such as intrinsic intermittency and anisotropy

Distribution to the Astronomy Community of the Compressed Digitized Sky Survey

Science.gov (United States)

Postman, Marc

1996-03-01

The Space Telescope Science Institute has compressed an all-sky collection of ground-based images and has printed the data on a two volume, 102 CD-ROM disc set. The first part of the survey (containing images of the southern sky) was published in May 1994. The second volume (containing images of the northern sky) was published in January 1995. Software which manages the image retrieval is included with each volume. The Astronomical Society of the Pacific (ASP) is handling the distribution of the lOx compressed data and has sold 310 sets as of October 1996. ASP is also handling the distribution of the recently published 100x version of the northern sky survey which is publicly available at a low cost. The target markets for the 100x compressed data set are the amateur astronomy community, educational institutions, and the general public. During the next year, we plan to publish the first version of a photometric calibration database which will allow users of the compressed sky survey to determine the brightness of stars in the images.

Distributed Two-Dimensional Fourier Transforms on DSPs with an Application for Phase Retrieval

Science.gov (United States)

Smith, Jeffrey Scott

2006-01-01

Many applications of two-dimensional Fourier Transforms require fixed timing as defined by system specifications. One example is image-based wavefront sensing. The image-based approach has many benefits, yet it is a computational intensive solution for adaptive optic correction, where optical adjustments are made in real-time to correct for external (atmospheric turbulence) and internal (stability) aberrations, which cause image degradation. For phase retrieval, a type of image-based wavefront sensing, numerous two-dimensional Fast Fourier Transforms (FFTs) are used. To meet the required real-time specifications, a distributed system is needed, and thus, the 2-D FFT necessitates an all-to-all communication among the computational nodes. The 1-D floating point FFT is very efficient on a digital signal processor (DSP). For this study, several architectures and analysis of such are presented which address the all-to-all communication with DSPs. Emphasis of this research is on a 64-node cluster of Analog Devices TigerSharc TS-101 DSPs.

The influence of learning methods on collaboration: prior repeated retrieval enhances retrieval organization, abolishes collaborative inhibition, and promotes post-collaborative memory.

Science.gov (United States)

Congleton, Adam R; Rajaram, Suparna

2011-11-01

Research on collaborative memory has unveiled the counterintuitive yet robust phenomenon that collaboration impairs group recall. A candidate explanation for this collaborative inhibition effect is the disruption of people's idiosyncratic retrieval strategies during collaboration, and it is hypothesized that employing methods that improve one's organization protects against retrieval disruption. Here it is investigated how one's learning method during the study phase--defined as either repeatedly studying or repeatedly retrieving information--influences retrieval organization and what effects this has on collaborative recall and post-collaborative individual recall. Results show that repeated retrieval consistently eliminated collaborative inhibition. This enabled participants to gain the most from re-exposure to materials recalled by their partners that they themselves did not recall and led to improvements in their individual memory following collaboration. This repeated retrieval advantage stemmed from the preferential manner in which this learning method strengthened retrieval organization. Findings are also discussed that reveal a relationship between retrieval organization and the interaction observed between learning method and short versus long delay seen in the testing effect literature. Finally, results show that the elusive benefits of cross-cuing during collaboration may be best detected with a longer study-test delay. Together, these findings illuminate when and how collaboration can enhance memory.

Phase transitions to 120 GPa for shock-compressed pyrolytic and hot-pressed boron nitride

International Nuclear Information System (INIS)

Gust, W.H.; Young, D.A.

1977-01-01

Shock-compression characteristics of two types of hexagonal graphitelike boron nitride have been investigated. Highly oriented very pure pyrolytic boron nitride exhibits shock-velocity versus particle-velocity discontinuities that appear to be manifestations of the initiation of a sluggish phase transition. This transition begins at 20 GPa and is driven to completion (melting) at 75 GPa. Discontinuities in the plot for impure hot-pressed boron nitride indicate initiation at 10 GPa and completion at 20 GPa. The (U/sub s/, U/sub p/) plots follow essentially the same paths for 4.0 < U/sub p/ < 5.2 km/sec. No evidence for a transition to a metalliclike state was seen. Temperature calculations indicate that the material is liquid above approx.80 GPa

Correlation and image compression for limited-bandwidth CCD.

Energy Technology Data Exchange (ETDEWEB)

Thompson, Douglas G.

2005-07-01

As radars move to Unmanned Aerial Vehicles with limited-bandwidth data downlinks, the amount of data stored and transmitted with each image becomes more significant. This document gives the results of a study to determine the effect of lossy compression in the image magnitude and phase on Coherent Change Detection (CCD). We examine 44 lossy compression types, plus lossless zlib compression, and test each compression method with over 600 CCD image pairs. We also derive theoretical predictions for the correlation for most of these compression schemes, which compare favorably with the experimental results. We recommend image transmission formats for limited-bandwidth programs having various requirements for CCD, including programs which cannot allow performance degradation and those which have stricter bandwidth requirements at the expense of CCD performance.

Excitonic metal-insulator phase transition of the Mott type in compressed calcium

Science.gov (United States)

Voronkova, T. O.; Sarry, A. M.; Sarry, M. F.; Skidan, S. G.

2017-05-01

It has been experimentally found that, under the static compression of a calcium crystal at room temperature, it undergoes a series of structural phase transitions: face-centered cubic lattice → body-centered cubic lattice → simple cubic lattice. It has been decided to investigate precisely the simple cubic lattice (because it is an alternative lattice) with the aim of elucidating the possibility of the existence of other (nonstructural) phase transitions in it by using for this purpose the Hubbard model for electrons with half-filled ns-bands and preliminarily transforming the initial electronic system into an electron-hole system by means of the known Shiba operators (applicable only to alternative lattices). This transformation leads to the fact that, in the new system of fermions, instead of the former repulsion, there is an attraction between electrons and holes. Elementary excitations of this new system are bound boson pairs—excitons. This system of fermions has been quantitatively analyzed by jointly using the equation-of-motion method and the direct algebraic method. The numerical integration of the analytically exact transcendental equations derived from the first principles for alternative (one-, two-, and three-dimensional) lattices has demonstrated that, in systems of two-species (electrons + hole) fermions, temperature-induced metal-insulator phase transitions of the Mott type are actually possible. Moreover, all these crystals are in fact excitonic insulators. This conclusion is in complete agreement with the analytically exact calculations of the ground state of a one-dimensional crystal (with half-filled bands), which were performed by Lieb and Wu with the aim to find out the Mott insulator-metal transition of another type.

Implicit proactive interference, age, and automatic versus controlled retrieval strategies.

Science.gov (United States)

Ikier, Simay; Yang, Lixia; Hasher, Lynn

2008-05-01

We assessed the extent to which implicit proactive interference results from automatic versus controlled retrieval among younger and older adults. During a study phase, targets (e.g., "ALLERGY") either were or were not preceded by nontarget competitors (e.g., "ANALOGY"). After a filled interval, the participants were asked to complete word fragments, some of which cued studied words (e.g., "A_L_ _GY"). Retrieval strategies were identified by the difference in response speed between a phase containing fragments that cued only new words and a phase that included a mix of fragments cuing old and new words. Previous results were replicated: Proactive interference was found in implicit memory, and the negative effects were greater for older than for younger adults. Novel findings demonstrate two retrieval processes that contribute to interference: an automatic one that is age invariant and a controlled process that can reduce the magnitude of the automatic interference effects. The controlled process, however, is used effectively only by younger adults. This pattern of findings potentially explains age differences in susceptibility to proactive interference.

Linearly decoupled energy-stable numerical methods for multi-component two-phase compressible flow

KAUST Repository

Kou, Jisheng

2017-12-06

In this paper, for the first time we propose two linear, decoupled, energy-stable numerical schemes for multi-component two-phase compressible flow with a realistic equation of state (e.g. Peng-Robinson equation of state). The methods are constructed based on the scalar auxiliary variable (SAV) approaches for Helmholtz free energy and the intermediate velocities that are designed to decouple the tight relationship between velocity and molar densities. The intermediate velocities are also involved in the discrete momentum equation to ensure a consistency relationship with the mass balance equations. Moreover, we propose a component-wise SAV approach for a multi-component fluid, which requires solving a sequence of linear, separate mass balance equations. We prove that the methods have the unconditional energy-dissipation feature. Numerical results are presented to verify the effectiveness of the proposed methods.

Improved ultrashort pulse-retrieval algorithm for frequency-resolved optical gating

International Nuclear Information System (INIS)

DeLong, K.W.; Trebino, R.

1994-01-01

We report on significant improvements in the pulse-retrieval algorithm used to reconstruct the amplitude and the phase of ultrashort optical pulses from the experimental frequency-resolved optical gating trace data in the polarization-gate geometry. These improvements involve the use of an intensity constraint, an overcorrection technique, and a multidimensional minimization scheme. While the previously published, basic algorithm converged for most common ultrashort pulses, it failed to retrieve pulses with significant intensity substructure. The improved composite algorithm successfully converges for such pulses. It can now retrieve essentially all pulses of practical interest. We present examples of complex waveforms that were retrieved by the improved algorithm

Full-frame compression of discrete wavelet and cosine transforms

Science.gov (United States)

Lo, Shih-Chung B.; Li, Huai; Krasner, Brian; Freedman, Matthew T.; Mun, Seong K.

1995-04-01

At the foreground of computerized radiology and the filmless hospital are the possibilities for easy image retrieval, efficient storage, and rapid image communication. This paper represents the authors' continuous efforts in compression research on full-frame discrete wavelet (FFDWT) and full-frame discrete cosine transforms (FFDCT) for medical image compression. Prior to the coding, it is important to evaluate the global entropy in the decomposed space. It is because of the minimum entropy, that a maximum compression efficiency can be achieved. In this study, each image was split into the top three most significant bit (MSB) and the remaining remapped least significant bit (RLSB) images. The 3MSB image was compressed by an error-free contour coding and received an average of 0.1 bit/pixel. The RLSB image was either transformed to a multi-channel wavelet or the cosine transform domain for entropy evaluation. Ten x-ray chest radiographs and ten mammograms were randomly selected from our clinical database and were used for the study. Our results indicated that the coding scheme in the FFDCT domain performed better than in FFDWT domain for high-resolution digital chest radiographs and mammograms. From this study, we found that decomposition efficiency in the DCT domain for relatively smooth images is higher than that in the DWT. However, both schemes worked just as well for low resolution digital images. We also found that the image characteristics of the `Lena' image commonly used in the compression literature are very different from those of radiological images. The compression outcome of the radiological images can not be extrapolated from the compression result based on the `Lena.'

A compressible two-phase model for dispersed particle flows with application from dense to dilute regimes

Energy Technology Data Exchange (ETDEWEB)

McGrath, Thomas P., E-mail: thomas.p.mcgrath@navy.mil [Naval Surface Warfare Center Indian Head Explosive Ordnance Disposal Technology Division, 4013 Fowler Rd., Indian Head, Maryland 20640 (United States); St Clair, Jeffrey G. [Naval Surface Warfare Center Indian Head Explosive Ordnance Disposal Technology Division, 4013 Fowler Rd., Indian Head, Maryland 20640 (United States); Department of Mechanical and Aerospace Engineering, University of Florida, 231 MAE-A, P.O. Box 116250, Gainesville, Florida 32611 (United States); Balachandar, S. [Department of Mechanical and Aerospace Engineering, University of Florida, 231 MAE-A, P.O. Box 116250, Gainesville, Florida 32611 (United States)

2016-05-07

Multiphase flows are present in many important fields ranging from multiphase explosions to chemical processing. An important subset of multiphase flow applications involves dispersed materials, such as particles, droplets, and bubbles. This work presents an Eulerian–Eulerian model for multiphase flows containing dispersed particles surrounded by a continuous media such as air or water. Following a large body of multiphase literature, the driving force for particle acceleration is modeled as a direct function of both the continuous-phase pressure gradient and the gradient of intergranular stress existing within the particle phase. While the application of these two components of driving force is well accepted in much of the literature, other models exist in which the particle-phase pressure gradient itself drives particle motion. The multiphase model treats all phases as compressible and is derived to ensure adherence to the 2nd Law of Thermodynamics. The governing equations are presented and discussed, and a characteristic analysis shows the model to be hyperbolic, with a degeneracy in the case that the intergranular stress, which is modeled as a configuration pressure, is zero. Finally, results from a two sample problems involving shock-induced particle dispersion are presented. The results agree well with experimental measurements, providing initial confidence in the proposed model.

A renormalization group scaling analysis for compressible two-phase flow

International Nuclear Information System (INIS)

Chen, Y.; Deng, Y.; Glimm, J.; Li, G.; Zhang, Q.; Sharp, D.H.

1993-01-01

Computational solutions to the Rayleigh--Taylor fluid mixing problem, as modeled by the two-fluid two-dimensional Euler equations, are presented. Data from these solutions are analyzed from the point of view of Reynolds averaged equations, using scaling laws derived from a renormalization group analysis. The computations, carried out with the front tracking method on an Intel iPSC/860, are highly resolved and statistical convergence of ensemble averages is achieved. The computations are consistent with the experimentally observed growth rates for nearly incompressible flows. The dynamics of the interior portion of the mixing zone is simplified by the use of scaling variables. The size of the mixing zone suggests fixed-point behavior. The profile of statistical quantities within the mixing zone exhibit self-similarity under fixed-point scaling to a limited degree. The effect of compressibility is also examined. It is found that, for even moderate compressibility, the growth rates fail to satisfy universal scaling, and moreover, increase significantly with increasing compressibility. The growth rates predicted from a renormalization group fixed-point model are in a reasonable agreement with the results of the exact numerical simulations, even for flows outside of the incompressible limit

A parallelizable compression scheme for Monte Carlo scatter system matrices in PET image reconstruction

International Nuclear Information System (INIS)

Rehfeld, Niklas; Alber, Markus

2007-01-01

Scatter correction techniques in iterative positron emission tomography (PET) reconstruction increasingly utilize Monte Carlo (MC) simulations which are very well suited to model scatter in the inhomogeneous patient. Due to memory constraints the results of these simulations are not stored in the system matrix, but added or subtracted as a constant term or recalculated in the projector at each iteration. This implies that scatter is not considered in the back-projector. The presented scheme provides a method to store the simulated Monte Carlo scatter in a compressed scatter system matrix. The compression is based on parametrization and B-spline approximation and allows the formation of the scatter matrix based on low statistics simulations. The compression as well as the retrieval of the matrix elements are parallelizable. It is shown that the proposed compression scheme provides sufficient compression so that the storage in memory of a scatter system matrix for a 3D scanner is feasible. Scatter matrices of two different 2D scanner geometries were compressed and used for reconstruction as a proof of concept. Compression ratios of 0.1% could be achieved and scatter induced artifacts in the images were successfully reduced by using the compressed matrices in the reconstruction algorithm

Development of retrievability plans

International Nuclear Information System (INIS)

Richardson, P.J.

1999-03-01

It has become clear, from monitoring of many national programmes for siting of final repositories for radioactive waste disposal, that the potential or otherwise for retrievability of emplaced wastes is the one issue in particular which is repeatedly raised during public consultation and interaction. Although even those repositories which may be constructed over the next decades will operate for many decades more and be sealed only after a long-term monitoring phase, there is little operational pressure to finalise retrievability concepts. However, as siting processes require detailed conceptual designs to be developed, as do the associated safety assessment exercises, it is becoming increasingly recognised that the potential for retrieval must be examined now. This report is the culmination of a short project carried out for the Swedish National Co-ordinator for Nuclear Waste Disposal to examine the situation as regards the development and possible implementation of retrievability as an integral part of a disposal concept for nuclear waste. Because of the short work period involved, it can at best be only an overview, designed to provide a broad picture of current plans. The Swedish Nuclear Power Inspectorate has begun to examine the issue, and a report is due later in 1999. A major collaborative investigation, which began in March 1998, is also currently underway under the auspices of the EU, but only involves implementing agencies from the various Member States. This report is intended to serve as background to these other studies when they appear. Utilising currently available information, as well as personal contacts, those countries currently examining retrievability or reversibility of disposal in some form have been identified. Information regarding these proposals has been collated, and contact made with relevant agencies and national regulatory bodies where possible. The report includes some review of the technical aspects of retrievability, with especial

Identification of physical properties for the retrieval data quality objective process

International Nuclear Information System (INIS)

Gates, C.M.; Beckette, M.R.

1995-06-01

This activity supports the retrieval data quality objective (DQO) process by identifying the material properties that are important to the design, development, and operation of retrieval equipment; the activity also provides justification for characterizing those properties. These properties, which control tank waste behavior during retrieval operations, are also critical to the development of valid physical simulants for designing retrieval equipment. The waste is to be retrieved in a series of four steps. First, a selected retrieval technology breaks up or dislodges the waste into subsequently smaller pieces. Then, the dislodged waste is conveyed out of the tank through the conveyance line. Next, the waste flows into a separator unit that separates the gaseous phase from the liquid and solid phases. Finally, a unit may be present to condition the slurried waste before transporting it to the treatment facility. This document describes the characterization needs for the proposed processes to accomplish waste retrieval. Baseline mobilization technologies include mixer pump technology, sluicing, and high-pressure water-jet cutting. Other processes that are discussed in this document include slurry formation, pneumatic conveyance, and slurry transport. Section 2.0 gives a background of the DQO process and the different retrieval technologies. Section 3.0 provides the mechanistic descriptions and material properties critical to the different technologies and processes. Supplemental information on specific technologies and processes is provided in the appendices. Appendix A contains a preliminary sluicing model, and Appendices B and C cover pneumatic transport and slurry transport, respectively, as prepared for this document. Appendix D contains sample calculations for various equations

A novel crystal-analyzer phase retrieval algorithm and its noise property.

Science.gov (United States)

Bao, Yuan; Wang, Yan; Li, Panyun; Wu, Zhao; Shao, Qigang; Gao, Kun; Wang, Zhili; Ju, Zaiqiang; Zhang, Kai; Yuan, Qingxi; Huang, Wanxia; Zhu, Peiping; Wu, Ziyu

2015-05-01

A description of the rocking curve in diffraction enhanced imaging (DEI) is presented in terms of the angular signal response function and a simple multi-information retrieval algorithm based on the cosine function fitting. A comprehensive analysis of noise properties of DEI is also given considering the noise transfer characteristic of the X-ray source. The validation has been performed with synchrotron radiation experimental data and Monte Carlo simulations based on the Geant4 toolkit combined with the refractive process of X-rays, which show good agreement with each other. Moreover, results indicate that the signal-to-noise ratios of the refraction and scattering images are about one order of magnitude better than that of the absorption image at the edges of low-Z samples. The noise penalty is drastically reduced with the increasing photon flux and visibility. Finally, this work demonstrates that the analytical method can build an interesting connection between DEI and GDPCI (grating-based differential phase contrast imaging) and is widely suitable for a variety of measurement noise in the angular signal response imaging prototype. The analysis significantly contributes to the understanding of noise characteristics of DEI images and may allow improvements to the signal-to-noise ratio in biomedical and material science imaging.

DNABIT Compress – Genome compression algorithm

Science.gov (United States)

Rajarajeswari, Pothuraju; Apparao, Allam

2011-01-01

Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, “DNABIT Compress” for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our proposed algorithm achieves the best compression ratio for DNA sequences for larger genome. Significantly better compression results show that “DNABIT Compress” algorithm is the best among the remaining compression algorithms. While achieving the best compression ratios for DNA sequences (Genomes),our new DNABIT Compress algorithm significantly improves the running time of all previous DNA compression programs. Assigning binary bits (Unique BIT CODE) for (Exact Repeats, Reverse Repeats) fragments of DNA sequence is also a unique concept introduced in this algorithm for the first time in DNA compression. This proposed new algorithm could achieve the best compression ratio as much as 1.58 bits/bases where the existing best methods could not achieve a ratio less than 1.72 bits/bases. PMID:21383923

Economic and technical feasibility study of compressed air storage

Energy Technology Data Exchange (ETDEWEB)

1976-03-01

The results of a study of the economic and technical feasibility of compressed air energy storage (CAES) are presented. The study, which concentrated primarily on the application of underground air storage with combustion turbines, consisted of two phases. In the first phase a general assessment of the technical alternatives, economic characteristics and the institutional constraints associated with underground storage of compressed air for utility peaking application was carried out. The goal of this assessment was to identify potential barrier problems and to define the incentive for the implementation of compressed air storage. In the second phase, the general conclusions of the assessment were tested by carrying out the conceptual design of a CAES plant at two specific sites, and a program of further work indicated by the assessment study was formulated. The conceptual design of a CAES plant employing storage in an aquifer and that of a plant employing storage in a conventionally excavated cavern employing a water leg to maintain constant pressure are shown. Recommendations for further work, as well as directions of future turbo-machinery development, are made. It is concluded that compressed air storage is technically feasible for off-peak energy storage, and, depending on site conditions, CAES plants may be favored over simple cycle turbine plants to meet peak demands. (LCL)

A retrieval-based approach to eliminating hindsight bias.

Science.gov (United States)

Van Boekel, Martin; Varma, Keisha; Varma, Sashank

2017-03-01

Individuals exhibit hindsight bias when they are unable to recall their original responses to novel questions after correct answers are provided to them. Prior studies have eliminated hindsight bias by modifying the conditions under which original judgments or correct answers are encoded. Here, we explored whether hindsight bias can be eliminated by manipulating the conditions that hold at retrieval. Our retrieval-based approach predicts that if the conditions at retrieval enable sufficient discrimination of memory representations of original judgments from memory representations of correct answers, then hindsight bias will be reduced or eliminated. Experiment 1 used the standard memory design to replicate the hindsight bias effect in middle-school students. Experiments 2 and 3 modified the retrieval phase of this design, instructing participants beforehand that they would be recalling both their original judgments and the correct answers. As predicted, this enabled participants to form compound retrieval cues that discriminated original judgment traces from correct answer traces, and eliminated hindsight bias. Experiment 4 found that when participants were not instructed beforehand that they would be making both recalls, they did not form discriminating retrieval cues, and hindsight bias returned. These experiments delineate the retrieval conditions that produce-and fail to produce-hindsight bias.

Annotation and retrieval system of CAD models based on functional semantics

Science.gov (United States)

Wang, Zhansong; Tian, Ling; Duan, Wenrui

2014-11-01

CAD model retrieval based on functional semantics is more significant than content-based 3D model retrieval during the mechanical conceptual design phase. However, relevant research is still not fully discussed. Therefore, a functional semantic-based CAD model annotation and retrieval method is proposed to support mechanical conceptual design and design reuse, inspire designer creativity through existing CAD models, shorten design cycle, and reduce costs. Firstly, the CAD model functional semantic ontology is constructed to formally represent the functional semantics of CAD models and describe the mechanical conceptual design space comprehensively and consistently. Secondly, an approach to represent CAD models as attributed adjacency graphs(AAG) is proposed. In this method, the geometry and topology data are extracted from STEP models. On the basis of AAG, the functional semantics of CAD models are annotated semi-automatically by matching CAD models that contain the partial features of which functional semantics have been annotated manually, thereby constructing CAD Model Repository that supports model retrieval based on functional semantics. Thirdly, a CAD model retrieval algorithm that supports multi-function extended retrieval is proposed to explore more potential creative design knowledge in the semantic level. Finally, a prototype system, called Functional Semantic-based CAD Model Annotation and Retrieval System(FSMARS), is implemented. A case demonstrates that FSMARS can successfully botain multiple potential CAD models that conform to the desired function. The proposed research addresses actual needs and presents a new way to acquire CAD models in the mechanical conceptual design phase.

EXAFS Phase Retrieval Solution Tracking for Complex Multi-Component System: Synthesized Topological Inverse Computation

International Nuclear Information System (INIS)

Lee, Jay Min; Yang, Dong-Seok; Bunker, Grant B

2013-01-01

Using the FEFF kernel A(k,r), we describe the inverse computation from χ(k)-data to g(r)-solution in terms of a singularity regularization method based on complete Bayesian statistics process. In this work, we topologically decompose the system-matched invariant projection operators into two distinct types, (A + AA + A) and (AA + AA + ), and achieved Synthesized Topological Inversion Computation (STIC), by employing a 12-operator-closed-loop emulator of the symplectic transformation. This leads to a numerically self-consistent solution as the optimal near-singular regularization parameters are sought, dramatically suppressing instability problems connected with finite precision arithmetic in ill-posed systems. By statistically correlating a pair of measured data, it was feasible to compute an optimal EXAFS phase retrieval solution expressed in terms of the complex-valued χ(k), and this approach was successfully used to determine the optimal g(r) for a complex multi-component system.

Effect of raw material ratios on the compressive strength of magnesium potassium phosphate chemically bonded ceramics

International Nuclear Information System (INIS)

Wang, Ai-juan; Yuan, Zhi-long; Zhang, Jiao; Liu, Lin-tao; Li, Jun-ming; Liu, Zheng

2013-01-01

The compressive strength of magnesium potassium phosphate chemically bonded ceramics is important in biomedical field. In this work, the compressive strength of magnesium potassium phosphate chemically bonded ceramics was investigated with different liquid-to-solid and MgO-to-KH 2 PO 4 ratios. X-ray diffractometer was applied to characterize its phase composition. The microstructure was imaged using a scanning electron microscope. The results showed that the compressive strength of the chemically bonded ceramics increased with the decrease of liquid-to-solid ratio due to the change of the packing density and the crystallinity of hydrated product. However, with the increase of MgO-to-KH 2 PO 4 weight ratio, its compressive strength increased firstly and then decreased. The low compressive strength in lower MgO-to-KH 2 PO 4 ratio might be explained by the existence of the weak phase KH 2 PO 4 . However, the low value of compressive strength with the higher MgO-to-KH 2 PO 4 ratio might be caused by lack of the joined phase in the hydrated product. Besides, it has been found that the microstructures were different in these two cases by the scanning electron microscope. Colloidal structure appeared for the samples with lower liquid-to-solid and higher MgO-to-KH 2 PO 4 ratios possibly because of the existence of amorphous hydrated products. The optimization of both liquid-to-solid and MgO-to-KH 2 PO 4 ratios was important to improve the compressive strength of magnesium potassium phosphate chemically bonded ceramics. - Highlights: • High packing density and amorphous hydrated phase improved the compressive strength. • Residual KH 2 PO 4 and poor bonding phase lower the compressive strength. • MPCBC fabricated with optimized parameters had the highest compressive strength

Tilt shift determinations with spatial-carrier phase-shift method in temporal phase-shift interferometry

International Nuclear Information System (INIS)

Liu, Qian; Wang, Yang; He, Jianguo; Ji, Fang; Wang, Baorui

2014-01-01

An algorithm is proposed to deal with tilt-shift errors in temporal phase-shift interferometry (PSI). In the algorithm, the tilt shifts are detected with the spatial-carrier phase-shift (SCPS) method and then the tilt shifts are applied as priori information to the least-squares fittings of phase retrieval. The algorithm combines the best features of the SCPS and the temporal PSI. The algorithm could be applied to interferograms of arbitrary aperture without data extrapolation for the Fourier transform is not involved. Simulations and experiments demonstrate the effectiveness of the algorithm. The statistics of simulation results show a satisfied accuracy in detecting tilt-shift errors. Comparisons of the measurements with and without environmental vibration show that the proposed algorithm could compensate tilt-shift errors and retrieve wavefront phase accurately. The algorithm provides an approach to retrieve wavefront phase for the temporal PSI in vibrating environment. (paper)

A Coded Aperture Compressive Imaging Array and Its Visual Detection and Tracking Algorithms for Surveillance Systems

Directory of Open Access Journals (Sweden)

Hanxiao Wu

2012-10-01

Full Text Available In this paper, we propose an application of a compressive imaging system to the problem of wide-area video surveillance systems. A parallel coded aperture compressive imaging system is proposed to reduce the needed high resolution coded mask requirements and facilitate the storage of the projection matrix. Random Gaussian, Toeplitz and binary phase coded masks are utilized to obtain the compressive sensing images. The corresponding motion targets detection and tracking algorithms directly using the compressive sampling images are developed. A mixture of Gaussian distribution is applied in the compressive image space to model the background image and for foreground detection. For each motion target in the compressive sampling domain, a compressive feature dictionary spanned by target templates and noises templates is sparsely represented. An l1 optimization algorithm is used to solve the sparse coefficient of templates. Experimental results demonstrate that low dimensional compressed imaging representation is sufficient to determine spatial motion targets. Compared with the random Gaussian and Toeplitz phase mask, motion detection algorithms using a random binary phase mask can yield better detection results. However using random Gaussian and Toeplitz phase mask can achieve high resolution reconstructed image. Our tracking algorithm can achieve a real time speed that is up to 10 times faster than that of the l1 tracker without any optimization.

Retrievability in the Belgian deep disposal concept in clay

International Nuclear Information System (INIS)

Preter, P. de

2000-01-01

While radioactive waste disposal implies that there is no intention to retrieve the waste, retrievability refers to the potential to retrieve the waste. So, retrievability can be an integrated element of a disposal solution. The different reasons for considering retrievability in the development of a disposal solution are discussed. Amongst them, the precautionary principle takes an important place. The development of a disposal solution should be in the first place safety-driven. The use of robust, high-integrity waste containers or overpacks contributes directly to safety, but also to the enhancement of the retrievability. Indeed, as long as the first barrier is intact, safe waste retrieval is in principle possible. By extending the period of easy access to the waste, i.e. by keeping the repository open during a longer period than needed for waste disposal operations, safety and retrievability goals can become contradictory. Indefinitely postponing the decision to close the repository enhances the risk of unforeseen perturbations of the disposal system and the risk of abandonment. This pleads of course for limiting the duration of the open phase to a reasonable period of time. Otherwise, the advantage of a prolonged open repository, as a means to prolong retrievability of the waste, is cancelled by the increasing risks of a system whose safety relies on societal, political and decisional stability, and not on a robust, passive multi-barrier system. (author)

Encoding and immediate retrieval tasks in patients with epilepsy: A functional MRI study of verbal and visual memory.

Science.gov (United States)

Saddiki, Najat; Hennion, Sophie; Viard, Romain; Ramdane, Nassima; Lopes, Renaud; Baroncini, Marc; Szurhaj, William; Reyns, Nicolas; Pruvo, Jean Pierre; Delmaire, Christine

2018-05-01

Medial lobe temporal structures and more specifically the hippocampus play a decisive role in episodic memory. Most of the memory functional magnetic resonance imaging (fMRI) studies evaluate the encoding phase; the retrieval phase being performed outside the MRI. We aimed to determine the ability to reveal greater hippocampal fMRI activations during retrieval phase. Thirty-five epileptic patients underwent a two-step memory fMRI. During encoding phase, subjects were requested to identify the feminine or masculine gender of faces and words presented, in order to encourage stimulus encoding. One hour after, during retrieval phase, subjects had to recognize the word and face. We used an event-related design to identify hippocampal activations. There was no significant difference between patients with left temporal lobe epilepsy, patients with right temporal lobe epilepsy and patients with extratemporal lobe epilepsy on verbal and visual learning task. For words, patients demonstrated significantly more bilateral hippocampal activation for retrieval task than encoding task and when the tasks were associated than during encoding alone. Significant difference was seen between face-encoding alone and face retrieval alone. This study demonstrates the essential contribution of the retrieval task during a fMRI memory task but the number of patients with hippocampal activations was greater when the two tasks were taken into account. Copyright © 2018. Published by Elsevier Masson SAS.

The importance of the retrievability of nuclear waste for the implementation of safeguard regimes for geologic repositories

International Nuclear Information System (INIS)

Swahn, J.A.

1999-01-01

To find acceptance for the construction and siting of spent fuel repositories retrievability of the spent fuel is a desired feature. In order to minimize the levels of safeguards needed for the plutonium in spent fuel repositories the retrievability should be as low as possible. These contradictory goals have be balanced against each other during the operational phase, before closure and after closure of the repository. Arguments can be made for having the spent fuel in a highly-retrievable state during the operational phase, in a semi-retrievable state at the end of the operational phase but before closure and in a low-retrievable state after closure. The spent fuel in a mined geologic repository will never be able to be considered irretrievable and surveillance of the repository will be needed for an extended time after closure. The level of safeguards needed will depend on the local, regional and global societal conditions for several hundred thousand years into the future. (author)

Poor chest compression quality with mechanical compressions in simulated cardiopulmonary resuscitation: a randomized, cross-over manikin study.

Science.gov (United States)

Blomberg, Hans; Gedeborg, Rolf; Berglund, Lars; Karlsten, Rolf; Johansson, Jakob

2011-10-01

Mechanical chest compression devices are being implemented as an aid in cardiopulmonary resuscitation (CPR), despite lack of evidence of improved outcome. This manikin study evaluates the CPR-performance of ambulance crews, who had a mechanical chest compression device implemented in their routine clinical practice 8 months previously. The objectives were to evaluate time to first defibrillation, no-flow time, and estimate the quality of compressions. The performance of 21 ambulance crews (ambulance nurse and emergency medical technician) with the authorization to perform advanced life support was studied in an experimental, randomized cross-over study in a manikin setup. Each crew performed two identical CPR scenarios, with and without the aid of the mechanical compression device LUCAS. A computerized manikin was used for data sampling. There were no substantial differences in time to first defibrillation or no-flow time until first defibrillation. However, the fraction of adequate compressions in relation to total compressions was remarkably low in LUCAS-CPR (58%) compared to manual CPR (88%) (95% confidence interval for the difference: 13-50%). Only 12 out of the 21 ambulance crews (57%) applied the mandatory stabilization strap on the LUCAS device. The use of a mechanical compression aid was not associated with substantial differences in time to first defibrillation or no-flow time in the early phase of CPR. However, constant but poor chest compressions due to failure in recognizing and correcting a malposition of the device may counteract a potential benefit of mechanical chest compressions. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Secure quantum private information retrieval using phase-encoded queries

Energy Technology Data Exchange (ETDEWEB)

Olejnik, Lukasz [CERN, 1211 Geneva 23, Switzerland and Poznan Supercomputing and Networking Center, Noskowskiego 12/14, PL-61-704 Poznan (Poland)

2011-08-15

We propose a quantum solution to the classical private information retrieval (PIR) problem, which allows one to query a database in a private manner. The protocol offers privacy thresholds and allows the user to obtain information from a database in a way that offers the potential adversary, in this model the database owner, no possibility of deterministically establishing the query contents. This protocol may also be viewed as a solution to the symmetrically private information retrieval problem in that it can offer database security (inability for a querying user to steal its contents). Compared to classical solutions, the protocol offers substantial improvement in terms of communication complexity. In comparison with the recent quantum private queries [Phys. Rev. Lett. 100, 230502 (2008)] protocol, it is more efficient in terms of communication complexity and the number of rounds, while offering a clear privacy parameter. We discuss the security of the protocol and analyze its strengths and conclude that using this technique makes it challenging to obtain the unconditional (in the information-theoretic sense) privacy degree; nevertheless, in addition to being simple, the protocol still offers a privacy level. The oracle used in the protocol is inspired both by the classical computational PIR solutions as well as the Deutsch-Jozsa oracle.

Secure quantum private information retrieval using phase-encoded queries

International Nuclear Information System (INIS)

Olejnik, Lukasz

2011-01-01

We propose a quantum solution to the classical private information retrieval (PIR) problem, which allows one to query a database in a private manner. The protocol offers privacy thresholds and allows the user to obtain information from a database in a way that offers the potential adversary, in this model the database owner, no possibility of deterministically establishing the query contents. This protocol may also be viewed as a solution to the symmetrically private information retrieval problem in that it can offer database security (inability for a querying user to steal its contents). Compared to classical solutions, the protocol offers substantial improvement in terms of communication complexity. In comparison with the recent quantum private queries [Phys. Rev. Lett. 100, 230502 (2008)] protocol, it is more efficient in terms of communication complexity and the number of rounds, while offering a clear privacy parameter. We discuss the security of the protocol and analyze its strengths and conclude that using this technique makes it challenging to obtain the unconditional (in the information-theoretic sense) privacy degree; nevertheless, in addition to being simple, the protocol still offers a privacy level. The oracle used in the protocol is inspired both by the classical computational PIR solutions as well as the Deutsch-Jozsa oracle.

Comparative study of incompressible and isothermal compressible flow solvers for cavitating flow dynamics

Energy Technology Data Exchange (ETDEWEB)

Park, Sun Ho [Korea Maritime and Ocean University, Busan (Korea, Republic of); Rhee, Shin Hyung [Seoul National University, Seoul (Korea, Republic of)

2015-08-15

Incompressible flow solvers are generally used for numerical analysis of cavitating flows, but with limitations in handling compressibility effects on vapor phase. To study compressibility effects on vapor phase and cavity interface, pressure-based incompressible and isothermal compressible flow solvers based on a cell-centered finite volume method were developed using the OpenFOAM libraries. To validate the solvers, cavitating flow around a hemispherical head-form body was simulated and validated against the experimental data. The cavity shedding behavior, length of a re-entrant jet, drag history, and the Strouhal number were compared between the two solvers. The results confirmed that computations of the cavitating flow including compressibility effects improved the reproduction of cavitation dynamics.

High intensity pulse self-compression in short hollow core capillaries

OpenAIRE

Butcher, Thomas J.; Anderson, Patrick N.; Horak, Peter; Frey, Jeremy G.; Brocklesby, William S.

2011-01-01

The drive for shorter pulses for use in techniques such as high harmonic generation and laser wakefield acceleration requires continual improvement in post-laser pulse compression techniques. The two most commonly used methods of pulse compression for high intensity pulses are hollow capillary compression via self-phase modulation (SPM) [1] and the more recently developed filamentation [2]. Both of these methods can require propagation distances of 1-3 m to achieve spectral broadening and com...

A two-dimensional, transient, compressible isothermal and two-phase model for the air-side electrode of PEM fuel cells

International Nuclear Information System (INIS)

Khakbaz Baboli, M.; Kermani, M.J.

2008-01-01

A two-dimensional, transient, compressible, isothermal and two-phase flow of reactant-product mixture in the air-side electrode of proton exchange membrane fuel cells (PEMFC) are numerically studied in the present paper. The mixture is composed of four species: oxygen, nitrogen, liquid water and water vapor. The governing PDE's are conservation of the water vapor and oxygen species, momentum equation of the mixture (gas+liquid), mass conservation of the liquid phase, and mass conservation of the mixture. In this study, a separate PDE for the mass conservation of the liquid water is solved to calculate the saturation levels. The capillary pressure was used to determine the slip velocity between the phases. A full compressible form of the momentum equation was used, with the ∇.V preserved in the equation. The Maxwell-Stefan equation was used to model the diffusive fluxes of the multi-component gas mixture. The strongly coupled equations are solved based on a recently developed finite volume SIMPLER scheme of S.V. Patankar, Numerical Heat Transfer and Fluid Flow, Hemisphere Publishing Corp., McGraw-Hill Book Company, 1984. The computational domain consists of two regions; an open area (gas delivery channel) linked to a porous gas diffusion layer (GDL). A single (unified) set of the PDE's are used for the whole domain with the corresponding properties of each sub-domain. A polarization curve for the whole spectrum of the dry and wet regions were obtained. The results were compared with the experiments of E.A. Ticianelli, C.R. Derouin, A. Redondo, S. Srinivasan, J. Electrochem. Soc. 135 (1988) 2209, and good agreements were achieved

Guenter Tulip Filter Retrieval Experience: Predictors of Successful Retrieval

International Nuclear Information System (INIS)

Turba, Ulku Cenk; Arslan, Bulent; Meuse, Michael; Sabri, Saher; Macik, Barbara Gail; Hagspiel, Klaus D.; Matsumoto, Alan H.; Angle, John F.

2010-01-01

We report our experience with Guenter Tulip filter placement indications, retrievals, and procedural problems, with emphasis on alternative retrieval techniques. We have identified 92 consecutive patients in whom a Guenter Tulip filter was placed and filter removal attempted. We recorded patient demographic information, filter placement and retrieval indications, procedures, standard and nonstandard filter retrieval techniques, complications, and clinical outcomes. The mean time to retrieval for those who experienced filter strut penetration was statistically significant [F(1,90) = 8.55, p = 0.004]. Filter strut(s) IVC penetration and successful retrieval were found to be statistically significant (p = 0.043). The filter hook-IVC relationship correlated with successful retrieval. A modified guidewire loop technique was applied in 8 of 10 cases where the hook appeared to penetrate the IVC wall and could not be engaged with a loop snare catheter, providing additional technical success in 6 of 8 (75%). Therefore, the total filter retrieval success increased from 88 to 95%. In conclusion, the Guenter Tulip filter has high successful retrieval rates with low rates of complication. Additional maneuvers such as a guidewire loop method can be used to improve retrieval success rates when the filter hook is endothelialized.

Inelastic response of silicon to shock compression.

Science.gov (United States)

Higginbotham, A; Stubley, P G; Comley, A J; Eggert, J H; Foster, J M; Kalantar, D H; McGonegle, D; Patel, S; Peacock, L J; Rothman, S D; Smith, R F; Suggit, M J; Wark, J S

2016-04-13

The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.

Weak-strong clustering transition in renewing compressible flows

OpenAIRE

Dhanagare, Ajinkya; Musacchio, Stefano; Vincenzi, Dario

2014-01-01

International audience; We investigate the statistical properties of Lagrangian tracers transported by a time-correlated compressible renewing flow. We show that the preferential sampling of the phase space performed by tracers yields significant differences between the Lagrangian statistics and its Eulerian counterpart. In particular, the effective compressibility experienced by tracers has a non-trivial dependence on the time correlation of the flow. We examine the consequence of this pheno...

EM-21 Retrieval Knowledge Center: Waste Retrieval Challenges

Energy Technology Data Exchange (ETDEWEB)

Fellinger, Andrew P.; Rinker, Michael W.; Berglin, Eric J.; Minichan, Richard L.; Poirier, Micheal R.; Gauglitz, Phillip A.; Martin, Bruce A.; Hatchell, Brian K.; Saldivar, Eloy; Mullen, O Dennis; Chapman, Noel F.; Wells, Beric E.; Gibbons, Peter W.

2009-04-10

EM-21 is the Waste Processing Division of the Office of Engineering and Technology, within the U.S. Department of Energy’s (DOE) Office of Environmental Management (EM). In August of 2008, EM-21 began an initiative to develop a Retrieval Knowledge Center (RKC) to provide the DOE, high level waste retrieval operators, and technology developers with centralized and focused location to share knowledge and expertise that will be used to address retrieval challenges across the DOE complex. The RKC is also designed to facilitate information sharing across the DOE Waste Site Complex through workshops, and a searchable database of waste retrieval technology information. The database may be used to research effective technology approaches for specific retrieval tasks and to take advantage of the lessons learned from previous operations. It is also expected to be effective for remaining current with state-of-the-art of retrieval technologies and ongoing development within the DOE Complex. To encourage collaboration of DOE sites with waste retrieval issues, the RKC team is co-led by the Savannah River National Laboratory (SRNL) and the Pacific Northwest National Laboratory (PNNL). Two RKC workshops were held in the Fall of 2008. The purpose of these workshops was to define top level waste retrieval functional areas, exchange lessons learned, and develop a path forward to support a strategic business plan focused on technology needs for retrieval. The primary participants involved in these workshops included retrieval personnel and laboratory staff that are associated with Hanford and Savannah River Sites since the majority of remaining DOE waste tanks are located at these sites. This report summarizes and documents the results of the initial RKC workshops. Technology challenges identified from these workshops and presented here are expected to be a key component to defining future RKC-directed tasks designed to facilitate tank waste retrieval solutions.

EM-21 Retrieval Knowledge Center: Waste Retrieval Challenges

International Nuclear Information System (INIS)

Fellinger, Andrew P.; Rinker, Michael W.; Berglin, Eric J.; Minichan, Richard L.; Poirier, Micheal R.; Gauglitz, Phillip A.; Martin, Bruce A.; Hatchell, Brian K.; Saldivar, Eloy; Mullen, O Dennis; Chapman, Noel F.; Wells, Beric E.; Gibbons, Peter W.

2009-01-01

EM-21 is the Waste Processing Division of the Office of Engineering and Technology, within the U.S. Department of Energy's (DOE) Office of Environmental Management (EM). In August of 2008, EM-21 began an initiative to develop a Retrieval Knowledge Center (RKC) to provide the DOE, high level waste retrieval operators, and technology developers with centralized and focused location to share knowledge and expertise that will be used to address retrieval challenges across the DOE complex. The RKC is also designed to facilitate information sharing across the DOE Waste Site Complex through workshops, and a searchable database of waste retrieval technology information. The database may be used to research effective technology approaches for specific retrieval tasks and to take advantage of the lessons learned from previous operations. It is also expected to be effective for remaining current with state-of-the-art of retrieval technologies and ongoing development within the DOE Complex. To encourage collaboration of DOE sites with waste retrieval issues, the RKC team is co-led by the Savannah River National Laboratory (SRNL) and the Pacific Northwest National Laboratory (PNNL). Two RKC workshops were held in the Fall of 2008. The purpose of these workshops was to define top level waste retrieval functional areas, exchange lessons learned, and develop a path forward to support a strategic business plan focused on technology needs for retrieval. The primary participants involved in these workshops included retrieval personnel and laboratory staff that are associated with Hanford and Savannah River Sites since the majority of remaining DOE waste tanks are located at these sites. This report summarizes and documents the results of the initial RKC workshops. Technology challenges identified from these workshops and presented here are expected to be a key component to defining future RKC-directed tasks designed to facilitate tank waste retrieval solutions

Swelling, Structure, and Phase Stability of Soft, Compressible Microgels

Science.gov (United States)

Denton, Alan R.; Urich, Matthew

Microgels are soft colloidal particles that swell when dispersed in a solvent. The equilibrium particle size is governed by a delicate balance of osmotic pressures, which can be tuned by varying single-particle properties and externally controlled conditions, such as temperature, pH, ionic strength, and concentration. Because of their tunable size and ability to encapsulate dye or drug molecules, microgels have practical relevance for biosensing, drug delivery, carbon capture, and filtration. Using Monte Carlo simulation, we model suspensions of microgels that interact via Hertzian elastic interparticle forces and can expand or contract via trial size changes governed by the Flory-Rehner free energy of cross-linked polymer gels. We analyze the influence of particle compressibility and size fluctuations on bulk structural and thermal properties by computing swelling ratios, radial distribution functions, static structure factors, osmotic pressures, and freezing densities. With increasing density, microgels progressively deswell and their intrinsic polydispersity broadens, while compressibility acts to forestall crystallization. This work was supported by the National Science Foundation under Grant No. DMR- 1106331.

Gas compression infrared generator

International Nuclear Information System (INIS)

Hug, W.F.

1980-01-01

A molecular gas is compressed in a quasi-adiabatic manner to produce pulsed radiation during each compressor cycle when the pressure and temperature are sufficiently high, and part of the energy is recovered during the expansion phase, as defined in U.S. Pat. No. 3,751,666; characterized by use of a cylinder with a reciprocating piston as a compressor

A combined finite volume-nonconforming finite element scheme for compressible two phase flow in porous media

KAUST Repository

Saad, Bilal Mohammed; Saad, Mazen Naufal B M

2014-01-01

We propose and analyze a combined finite volume-nonconforming finite element scheme on general meshes to simulate the two compressible phase flow in porous media. The diffusion term, which can be anisotropic and heterogeneous, is discretized by piecewise linear nonconforming triangular finite elements. The other terms are discretized by means of a cell-centered finite volume scheme on a dual mesh, where the dual volumes are constructed around the sides of the original mesh. The relative permeability of each phase is decentred according the sign of the velocity at the dual interface. This technique also ensures the validity of the discrete maximum principle for the saturation under a non restrictive shape regularity of the space mesh and the positiveness of all transmissibilities. Next, a priori estimates on the pressures and a function of the saturation that denote capillary terms are established. These stabilities results lead to some compactness arguments based on the use of the Kolmogorov compactness theorem, and allow us to derive the convergence of a subsequence of the sequence of approximate solutions to a weak solution of the continuous equations, provided the mesh size tends to zero. The proof is given for the complete system when the density of the each phase depends on its own pressure. © 2014 Springer-Verlag Berlin Heidelberg.

A combined finite volume-nonconforming finite element scheme for compressible two phase flow in porous media

KAUST Repository

Saad, Bilal Mohammed

2014-06-28

We propose and analyze a combined finite volume-nonconforming finite element scheme on general meshes to simulate the two compressible phase flow in porous media. The diffusion term, which can be anisotropic and heterogeneous, is discretized by piecewise linear nonconforming triangular finite elements. The other terms are discretized by means of a cell-centered finite volume scheme on a dual mesh, where the dual volumes are constructed around the sides of the original mesh. The relative permeability of each phase is decentred according the sign of the velocity at the dual interface. This technique also ensures the validity of the discrete maximum principle for the saturation under a non restrictive shape regularity of the space mesh and the positiveness of all transmissibilities. Next, a priori estimates on the pressures and a function of the saturation that denote capillary terms are established. These stabilities results lead to some compactness arguments based on the use of the Kolmogorov compactness theorem, and allow us to derive the convergence of a subsequence of the sequence of approximate solutions to a weak solution of the continuous equations, provided the mesh size tends to zero. The proof is given for the complete system when the density of the each phase depends on its own pressure. © 2014 Springer-Verlag Berlin Heidelberg.

Compression therapy in patients with venous leg ulcers.

Science.gov (United States)

Dissemond, Joachim; Assenheimer, Bernd; Bültemann, Anke; Gerber, Veronika; Gretener, Silvia; Kohler-von Siebenthal, Elisabeth; Koller, Sonja; Kröger, Knut; Kurz, Peter; Läuchli, Severin; Münter, Christian; Panfil, Eva-Maria; Probst, Sebastian; Protz, Kerstin; Riepe, Gunnar; Strohal, Robert; Traber, Jürg; Partsch, Hugo

2016-11-01

Wund-D.A.CH. is the umbrella organization of the various wound care societies in German-speaking countries. The present consensus paper on practical aspects pertinent to compression therapy in patients with venous leg ulcers was developed by experts from Germany, Austria, and Switzerland. In Europe, venous leg ulcers rank among the most common causes of chronic wounds. Apart from conservative and interventional wound and vein treatment, compression therapy represents the basis of all other therapeutic strategies. To that end, there are currently a wide variety of materials and systems available. While especially short-stretch bandages or multicomponent systems should be used in the initial decongestion phase, ulcer stocking systems are recommended for the subsequent maintenance phase. Another - to date, far less common - alternative are adaptive Velcro bandage systems. Medical compression stockings have proven particularly beneficial in the prevention of ulcer recurrence. The large number of treatment options currently available enables therapists to develop therapeutic concepts geared towards their patients' individual needs and abilities, thus resulting in good acceptance and adherence. Compression therapy plays a crucial role in the treatment of patients with venous leg ulcers. In recent years, a number of different treatment options have become available, their use and application differing among German-speaking countries. The present expert consensus is therefore meant to outline concrete recommendations for routine implementation of compression therapy in patients with venous leg ulcers. © 2016 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

Final Report 02-ERD-033: Rapid Resolidification of Metals using Dynamic Compression

International Nuclear Information System (INIS)

Streitz, F H; Nguyen, J H; Orlikowski, D; Minich, R; Moriarty, J A; Holmes, N C

2005-01-01

The purpose of this project is to develop a greater understanding of the kinetics involved during a liquid-solid phase transition occurring at high pressure and temperature. Kinetic limitations are known to play a large role in the dynamics of solidification at low temperatures, determining, e.g., whether a material crystallizes upon freezing or becomes an amorphous solid. The role of kinetics is not at all understood in transitions at high temperature when extreme pressures are involved. In order to investigate time scales during a dynamic compression experiment we needed to create an ability to alter the length of time spent by the sample in the transition region. Traditionally, the extreme high-pressure phase diagram is studied through a few static and dynamic techniques: static compression involving diamond anvil cells (DAC) [1], shock compression [2, 3], and quasi-isentropic compression [4, 5, 6, 7, 8, 9, 10]. Static DAC experiments explore equilibrium material properties along an isotherm or an isobar [1]. Dynamic material properties can be explored with shock compression [2, 3], probing single states on the Hugoniot, or with quasi-isentropic compression [4, 5, 6, 7, 8, 9, 10]. In the case of shocks, pressures variation typically occurs on a sub-nanosecond time scale or faster [11]. Previous quasi-isentropic techniques have yielded pressure ramps on the 10-100 nanosecond time-scale for samples that are several hundred microns thick [4, 5, 6, 7]. In order to understand kinetic effects at high temperatures and high pressures, we need to span a large dynamic range (strain rates, relaxation times, etc.) as well as control the thermodynamic path that the material experiences. Compression rates, for instance, need to bridge those of static experiments (seconds to hours) and those of the Z-accelerator (10 6 s -1 ) [4] or even laser ablation techniques (10 6 s -1 to 10 8 s -1 ) [7]. Here, we present a new technique that both extends the compression time to several

Mescalero Apache Tribe Monitored Retrievable Storage (MRS). Phase 1 feasibility study report

Energy Technology Data Exchange (ETDEWEB)

Peso, F.

1992-03-13

The Nuclear Waste Policy Act of 1982, as amended, authorizes the siting, construction and operation of a Monitored Retrievable Storage (MRS) facility. The MRS is intended to be used for the temporary storage of spent nuclear fuel from the nation`s nuclear power plants beginning as early as 1998. Pursuant to the Nuclear Waste Policy Act, the Office of the Nuclear Waste Negotiator was created. On October 7, 1991, the Nuclear Waste Negotiator invited the governors of states and the Presidents of Indian tribes to apply for government grants in order to conduct a study to assess under what conditions, if any, they might consider hosting an MRS facility. Pursuant to this invitation, on October 11, 1991 the Mescalero Apache Indian Tribe of Mescalero, NM applied for a grant to conduct a phased, preliminary study of the safety, technical, political, environmental, social and economic feasibility of hosting an MRS. The preliminary study included: (1) An investigative education process to facilitate the Tribe`s comprehensive understanding of the safety, environmental, technical, social, political, and economic aspects of hosting an MRS, and; (2) The development of an extensive program that is enabling the Tribe, in collaboration with the Negotiator, to reach an informed and carefully researched decision regarding the conditions, (if any), under which further pursuit of the MRS would be considered. The Phase 1 grant application enabled the Tribe to begin the initial activities necessary to determine whether further consideration is warranted for hosting the MRS facility. The Tribe intends to pursue continued study of the MRS in order to meet the following objectives: (1) Continuing the education process towards a comprehensive understanding of the safety, environmental, technical, social and economic aspects of the MRS; (2) Conducting an effective public participation and information program; (3) Participating in MRS meetings.

Multi-scale Modeling of Compressible Single-phase Flow in Porous Media using Molecular Simulation

KAUST Repository

Saad, Ahmed Mohamed

2016-05-01

In this study, an efficient coupling between Monte Carlo (MC) molecular simulation and Darcy-scale flow in porous media is presented. The cell-centered finite difference method with a non-uniform rectangular mesh were used to discretize the simulation domain and solve the governing equations. To speed up the MC simulations, we implemented a recently developed scheme that quickly generates MC Markov chains out of pre-computed ones, based on the reweighting and reconstruction algorithm. This method astonishingly reduces the required computational time by MC simulations from hours to seconds. In addition, the reweighting and reconstruction scheme, which was originally designed to work with the LJ potential model, is extended to work with a potential model that accounts for the molecular quadrupole moment of fluids with non-spherical molecules such as CO2. The potential model was used to simulate the thermodynamic equilibrium properties for single-phase and two-phase systems using the canonical ensemble and the Gibbs ensemble, respectively. Comparing the simulation results with the experimental data showed that the implemented model has an excellent fit outperforming the standard LJ model. To demonstrate the strength of the proposed coupling in terms of computational time efficiency and numerical accuracy in fluid properties, various numerical experiments covering different compressible single-phase flow scenarios were conducted. The novelty in the introduced scheme is in allowing an efficient coupling of the molecular scale and Darcy scale in reservoir simulators. This leads to an accurate description of the thermodynamic behavior of the simulated reservoir fluids; consequently enhancing the confidence in the flow predictions in porous media.

Content-Based Image Retrieval Based on Electromagnetism-Like Mechanism

Directory of Open Access Journals (Sweden)

Hamid A. Jalab

2013-01-01

Full Text Available Recently, many researchers in the field of automatic content-based image retrieval have devoted a remarkable amount of research looking for methods to retrieve the best relevant images to the query image. This paper presents a novel algorithm for increasing the precision in content-based image retrieval based on electromagnetism optimization technique. The electromagnetism optimization is a nature-inspired technique that follows the collective attraction-repulsion mechanism by considering each image as an electrical charge. The algorithm is composed of two phases: fitness function measurement and electromagnetism optimization technique. It is implemented on a database with 8,000 images spread across 80 classes with 100 images in each class. Eight thousand queries are fired on the database, and the overall average precision is computed. Experimental results of the proposed approach have shown significant improvement in the retrieval performance in regard to precision.

Dialysis grafts arterial plug: Retrieval using the tulip sheath device in vitro

International Nuclear Information System (INIS)

Sharafuddin, Melhem J.; Titus, Jack L.; Gu Xiaoping; Hunter, David W.; Amplatz, Kurt

1997-01-01

The 'arterial plug' is a resistant thrombus that frequently persists at the arterial anastomosis of clotted hemodialysis grafts following thrombolytic therapy. We studied the physical and morphological characteristics of the plug and determined the feasibility of transcatheter removal in vitro using the tulip compression thrombectomy system. Sixteen thrombus plugs were recovered during surgical thrombectomy of clotted human dialysis grafts. The physical and gross physical characteristics of all plugs were analyzed. Eight specimens were evaluated microscopically. Transcatheter compression thrombectomy of eight plugs was attempted in vitro. Each plug was embedded in a polyvinyl tube filled with newly clotted blood and connected to a flow circuit. First, balloon-assisted aspiration thrombectomy (BAT) of soft thrombus was performed, while sparing the distal-most segment containing the plug. The tulip sheath was then introduced facing the 'arterial end' of the tube. The thrombus segment containing the plug was pulled back into the tulip mesh using either a 3 Fr Fogarty balloon catheter or a self-expanding rake. The tulip was closed to compress and remove the trapped plug. Near-complete thrombectomy of soft clot was achieved in all tested tubes. Compression and retrieval of the entire arterial plug was successful in all except one, where only partial compression of the plug occurred, presumably due to fibrotic changes. No fragmentation or embolization occurred in the remaining procedures. Spongy consistency was noted in 94% of the specimens. Microscopic evaluation showed organized layered thrombus with compaction in five plugs. Transcatheter removal of a thrombus plug is feasible in vitro using the tulip compression-thrombectomy system

Picosecond chirped pulse compression in single-mode fibers

International Nuclear Information System (INIS)

Wenhua Cao; Youwei Zhang

1995-01-01

In this paper, the nonlinear propagation of picosecond chirped pulses in single mode fibers has been investigated both analytically and numerically. Results show that downchirped pulses can be compressed owing to normal group-velocity dispersion. The compression ratio depends both on the initial peak power and on the initial frequency chirp of the input pulse. While the compression ratio depends both on the initial peak power and on the initial frequency chirp of the input pulse. While the compression ratio increases with the negative frequency chirp, it decreases with the initial peak power of the input pulse. This means that the self-phase modulation induced nonlinear frequency chirp which is linear and positive (up-chirp) over a large central region of the pulse and tends to cancel the initial negative chirp of the pulse. It is also shown that, as the negative chirped pulse compresses temporally, it synchronously experiences a spectral narrowing

Competitive Semantic Memory Retrieval: Temporal Dynamics Revealed by Event-Related Potentials.

Directory of Open Access Journals (Sweden)

Robin Hellerstedt

Full Text Available Memories compete for retrieval when they are related to a common retrieval cue. Previous research has shown that retrieval of a target memory may lead to subsequent retrieval-induced forgetting (RIF of currently irrelevant competing memories. In the present study, we investigated the time course of competitive semantic retrieval and examined the neurocognitive mechanisms underlying RIF. We contrasted two theoretical accounts of RIF by examining a critical aspect of this memory phenomenon, namely the extent to which it depends on successful retrieval of the target memory. Participants first studied category-exemplar word-pairs (e.g. Fruit-Apple. Next, we recorded electrophysiological measures of brain activity while the participants performed a competitive semantic cued-recall task. In this task, the participants were provided with the studied categories but they were instructed to retrieve other unstudied exemplars (e.g. Fruit-Ma__?. We investigated the event-related potential (ERP correlates of retrieval success by comparing ERPs from successful and failed retrieval trials. To isolate the ERP correlates of continuous retrieval attempts from the ERP correlates of retrieval success, we included an impossible retrieval condition, with incompletable word-stem cues (Drinks-Wy__ and compared it with a non-retrieval presentation baseline condition (Occupation-Dentist. The participants' memory for all the studied exemplars was tested in the final phase of the experiment. Taken together, the behavioural results suggest that RIF is independent of target retrieval. Beyond investigating the mechanisms underlying RIF, the present study also elucidates the temporal dynamics of semantic cued-recall by isolating the ERP correlates of retrieval attempt and retrieval success. The ERP results revealed that retrieval attempt is reflected in a late posterior negativity, possibly indicating construction of candidates for completing the word-stem cue and retrieval

Competitive Semantic Memory Retrieval: Temporal Dynamics Revealed by Event-Related Potentials

Science.gov (United States)

Hellerstedt, Robin; Johansson, Mikael

2016-01-01

Memories compete for retrieval when they are related to a common retrieval cue. Previous research has shown that retrieval of a target memory may lead to subsequent retrieval-induced forgetting (RIF) of currently irrelevant competing memories. In the present study, we investigated the time course of competitive semantic retrieval and examined the neurocognitive mechanisms underlying RIF. We contrasted two theoretical accounts of RIF by examining a critical aspect of this memory phenomenon, namely the extent to which it depends on successful retrieval of the target memory. Participants first studied category-exemplar word-pairs (e.g. Fruit—Apple). Next, we recorded electrophysiological measures of brain activity while the participants performed a competitive semantic cued-recall task. In this task, the participants were provided with the studied categories but they were instructed to retrieve other unstudied exemplars (e.g. Fruit—Ma__?). We investigated the event-related potential (ERP) correlates of retrieval success by comparing ERPs from successful and failed retrieval trials. To isolate the ERP correlates of continuous retrieval attempts from the ERP correlates of retrieval success, we included an impossible retrieval condition, with incompletable word-stem cues (Drinks—Wy__) and compared it with a non-retrieval presentation baseline condition (Occupation—Dentist). The participants’ memory for all the studied exemplars was tested in the final phase of the experiment. Taken together, the behavioural results suggest that RIF is independent of target retrieval. Beyond investigating the mechanisms underlying RIF, the present study also elucidates the temporal dynamics of semantic cued-recall by isolating the ERP correlates of retrieval attempt and retrieval success. The ERP results revealed that retrieval attempt is reflected in a late posterior negativity, possibly indicating construction of candidates for completing the word-stem cue and retrieval

Competitive Semantic Memory Retrieval: Temporal Dynamics Revealed by Event-Related Potentials.

Science.gov (United States)

Hellerstedt, Robin; Johansson, Mikael

2016-01-01

Memories compete for retrieval when they are related to a common retrieval cue. Previous research has shown that retrieval of a target memory may lead to subsequent retrieval-induced forgetting (RIF) of currently irrelevant competing memories. In the present study, we investigated the time course of competitive semantic retrieval and examined the neurocognitive mechanisms underlying RIF. We contrasted two theoretical accounts of RIF by examining a critical aspect of this memory phenomenon, namely the extent to which it depends on successful retrieval of the target memory. Participants first studied category-exemplar word-pairs (e.g. Fruit-Apple). Next, we recorded electrophysiological measures of brain activity while the participants performed a competitive semantic cued-recall task. In this task, the participants were provided with the studied categories but they were instructed to retrieve other unstudied exemplars (e.g. Fruit-Ma__?). We investigated the event-related potential (ERP) correlates of retrieval success by comparing ERPs from successful and failed retrieval trials. To isolate the ERP correlates of continuous retrieval attempts from the ERP correlates of retrieval success, we included an impossible retrieval condition, with incompletable word-stem cues (Drinks-Wy__) and compared it with a non-retrieval presentation baseline condition (Occupation-Dentist). The participants' memory for all the studied exemplars was tested in the final phase of the experiment. Taken together, the behavioural results suggest that RIF is independent of target retrieval. Beyond investigating the mechanisms underlying RIF, the present study also elucidates the temporal dynamics of semantic cued-recall by isolating the ERP correlates of retrieval attempt and retrieval success. The ERP results revealed that retrieval attempt is reflected in a late posterior negativity, possibly indicating construction of candidates for completing the word-stem cue and retrieval monitoring

Retrievable Inferior Vena Cava Filters: Factors that Affect Retrieval Success

Energy Technology Data Exchange (ETDEWEB)

Geisbuesch, Philipp, E-mail: philippgeisbuesch@gmx.de; Benenati, James F.; Pena, Constantino S.; Couvillon, Joseph; Powell, Alex; Gandhi, Ripal; Samuels, Shaun; Uthoff, Heiko [Baptist Cardiac and Vascular Institute, Division of Vascular and Interventional Radiology (United States)

2012-10-15

Purpose: To report and analyze the indications, procedural success, and complications of retrievable inferior vena cava filters (rIVCF) placement and to identify parameters that influence retrieval attempt and failure. Methods: Between January 2005 and December 2010, a total of 200 patients (80 men, median age 67 years, range 11-95 years) received a rIVCF with the clinical possibility that it could be removed. All patients with rIVCF were prospectively entered into a database and followed until retrieval or a decision not to retrieve the filter was made. A retrospective analysis of this database was performed. Results: Sixty-one percent of patients had an accepted indication for filter placement; 39% of patients had a relative indication. There was a tendency toward a higher retrieval rate in patients with relative indications (40% vs. 55%, P = 0.076). Filter placement was technically successful in all patients, with no procedure-related mortality. The retrieval rate was 53%. Patient age of >80 years (odds ratio [OR] 0.056, P > 0.0001) and presence of malignancy (OR 0.303, P = 0.003) was associated with a significantly reduced probability for attempted retrieval. Retrieval failure occurred in 7% (6 of 91) of all retrieval attempts. A time interval of > 90 days between implantation and attempted retrieval was associated with retrieval failure (OR 19.8, P = 0.009). Conclusions: Patient age >80 years and a history of malignancy are predictors of a reduced probability for retrieval attempt. The rate of retrieval failure is low and seems to be associated with a time interval of >90 days between filter placement and retrieval.

Retrievable Inferior Vena Cava Filters: Factors that Affect Retrieval Success

International Nuclear Information System (INIS)

Geisbüsch, Philipp; Benenati, James F.; Peña, Constantino S.; Couvillon, Joseph; Powell, Alex; Gandhi, Ripal; Samuels, Shaun; Uthoff, Heiko

2012-01-01

Purpose: To report and analyze the indications, procedural success, and complications of retrievable inferior vena cava filters (rIVCF) placement and to identify parameters that influence retrieval attempt and failure. Methods: Between January 2005 and December 2010, a total of 200 patients (80 men, median age 67 years, range 11–95 years) received a rIVCF with the clinical possibility that it could be removed. All patients with rIVCF were prospectively entered into a database and followed until retrieval or a decision not to retrieve the filter was made. A retrospective analysis of this database was performed. Results: Sixty-one percent of patients had an accepted indication for filter placement; 39% of patients had a relative indication. There was a tendency toward a higher retrieval rate in patients with relative indications (40% vs. 55%, P = 0.076). Filter placement was technically successful in all patients, with no procedure-related mortality. The retrieval rate was 53%. Patient age of >80 years (odds ratio [OR] 0.056, P > 0.0001) and presence of malignancy (OR 0.303, P = 0.003) was associated with a significantly reduced probability for attempted retrieval. Retrieval failure occurred in 7% (6 of 91) of all retrieval attempts. A time interval of > 90 days between implantation and attempted retrieval was associated with retrieval failure (OR 19.8, P = 0.009). Conclusions: Patient age >80 years and a history of malignancy are predictors of a reduced probability for retrieval attempt. The rate of retrieval failure is low and seems to be associated with a time interval of >90 days between filter placement and retrieval.

Using Costal Chondrocytes to Engineer Articular Cartilage with Applications of Passive Axial Compression and Bioactive Stimuli.

Science.gov (United States)

Huwe, Le W; Sullan, Gurdeep K; Hu, Jerry C; Athanasiou, Kyriacos A

2018-03-01

Generating neocartilage with suitable mechanical integrity from a cell source that can circumvent chondrocyte scarcity is indispensable for articular cartilage regeneration strategies. Costal chondrocytes of the rib eliminate donor site morbidity in the articular joint, but it remains unclear how neocartilage formed from these cells responds to mechanical loading, especially if the intent is to use it in a load-bearing joint. In a series of three experiments, this study sought to determine efficacious parameters of passive axial compressive stimulation that would enable costal chondrocytes to synthesize mechanically robust cartilage. Experiment 1 determined a suitable time window for stimulation by its application during either the matrix synthesis phase, the maturation phase, or during both phases of the self-assembling process. The results showed that compressive stimulation at either time was effective in increasing instantaneous moduli by 92% and 87% in the synthesis and maturation phases, respectively. Compressive stimulation during both phases did not further improve properties beyond a one-time stimulation. The magnitude of passive axial compression was examined in Experiment 2 by applying 0, 3.3, 5.0, or 6.7 kPa stresses to the neocartilage. Unlike 6.7 kPa, both 3.3 and 5.0 kPa significantly increased neocartilage compressive properties by 42% and 48% over untreated controls, respectively. Experiment 3 examined how the passive axial compression regimen developed from the previous phases interacted with a bioactive regimen (transforming growth factor [TGF]-β1, chondroitinase ABC, and lysyl oxidase-like 2). Passive axial compression significantly improved the relaxation modulus compared with bioactive treatment alone. Furthermore, a combined treatment of compressive and bioactive stimulation improved the tensile properties of neocartilage 2.6-fold compared with untreated control. The ability to create robust articular cartilage from passaged costal

Elastic behavior of MFI-type zeolites: 3 - Compressibility of silicalite and mutinaite

Energy Technology Data Exchange (ETDEWEB)

Quartieri, Simona, E-mail: squartieri@unime.it [Dipartimento di Scienze della Terra, Universita di Messina, Viale Ferdinando Stagno d' Alcontres 31, 98166 Messina S. Agata (Italy); Arletti, Rossella [Dipartimento di Scienze Mineralogiche e Petrologiche, Via Valperga Caluso 35, 10125 Torino (Italy); Vezzalini, Giovanna [Dipartimento di Scienze della Terra, Universita di Modena e Reggio Emilia, Via S. Eufemia 19, 41100 Modena (Italy); Di Renzo, Francesco [Institut Charles Gerhardt de Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1, 8 rue Ecole Normale, 34296 Montpellier (France); Dmitriev, Vladimir [Swiss-Norwegian Beam Line at ESRF, BP220, 38043 Grenoble Cedex (France)

2012-07-15

We report the results of an in-situ synchrotron X-ray powder diffraction study - performed using silicone oil as 'non-penetrating' pressure transmitting medium - of the elastic behavior of three zeolites with MFI-type framework: the natural zeolite mutinaite and two silicalites (labeled A and B) synthesized under different conditions. While in mutinaite no symmetry change is observed as a function of pressure, a phase transition from monoclinic (P2{sub 1}/n) to orthorhombic (Pnma) symmetry occurs at about 1.0 GPa in the silicalite samples. This phase transition is irreversible upon decompression. The second order bulk moduli of silicalite A and silicalite B, calculated after the fulfillment of the phase transition, are: K{sub 0}=18.2(2) and K{sub 0}=14.3 (2) GPa, respectively. These values makes silicalite the most compressible zeolite among those up to now studied in silicone oil. The structural deformations induced by HP in silicalite A were investigated by means of complete Rietveld structural refinements, before and after the phase transition, at P{sub amb} and 0.9 GPa, respectively. The elastic behaviors of the three MFI-type zeolites here investigated were compared with those of Na-ZSM-5 and H-ZSM-5, studied in similar experimental conditions: the two silicalites - which are the phases with the highest Si/Al ratios and hence the lowest extraframework contents - show the highest compressibility. On the contrary, the most rigid material is mutinaite, which has a very complex extraframework composition characterized by a high number of cations and water molecules. - Graphical abstract: High-pressure behavior of silicalite compressed in silicone oil: projection of the structure along the [0 1 0] direction at Pamb(a), 0.9 GPa (b). (c) Comparison of the unit-cell volume variations as a function of pressure for mutinaite, H-ZSM5, Na-ZSM5, silicalite A, and silicalite B compressed in silicone oil. Highlights: Black-Right-Pointing-Pointer X-ray powder

Functional-anatomic study of episodic retrieval using fMRI. I. Retrieval effort versus retrieval success.

Science.gov (United States)

Buckner, R L; Koutstaal, W; Schacter, D L; Wagner, A D; Rosen, B R

1998-04-01

A number of recent functional imaging studies have identified brain areas activated during tasks involving episodic memory retrieval. The identification of such areas provides a foundation for targeted hypotheses regarding the more specific contributions that these areas make to episodic retrieval. As a beginning effort toward such an endeavor, whole-brain functional magnetic resonance imaging (fMRI) was used to examine 14 subjects during episodic word recognition in a block-designed fMRI experiment. Study conditions were manipulated by presenting either shallow or deep encoding tasks. This manipulation yielded two recognition conditions that differed with regard to retrieval effort and retrieval success: shallow encoding yielded low levels of recognition success with high levels of retrieval effort, and deep encoding yielded high levels of recognition success with low levels of effort. Many brain areas were activated in common by these two recognition conditions compared to a low-level fixation condition, including left and right prefrontal regions often detected during PET episodic retrieval paradigms (e.g., R. L. Buckner et al., 1996, J. Neurosci. 16, 6219-6235) thereby generalizing these findings to fMRI. Characterization of the activated regions in relation to the separate recognition conditions showed (1) bilateral anterior insular regions and a left dorsal prefrontal region were more active after shallow encoding, when retrieval demanded greatest effort, and (2) right anterior prefrontal cortex, which has been implicated in episodic retrieval, was most active during successful retrieval after deep encoding. We discuss these findings in relation to component processes involved in episodic retrieval and in the context of a companion study using event-related fMRI.

Density and adiabatic compressibility of the immiscible molten AgBr+LiCl mixture

Energy Technology Data Exchange (ETDEWEB)

Stepanov, Victor P. [Russian Academy of Sciences, Yekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry; Ural Federal Univ., Yekaterinburg (Russian Federation); Kulik, Nina P. [Russian Academy of Sciences, Yekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry

2017-07-01

The adiabatic compressibility, β, of the immiscible liquid mixture 0.52 LiCl+0.48 AgBr (the top of the miscibility gap) was experimentally investigated in the temperature range from the melting point to the critical mixing temperature using the sound velocity values, u, measured by the pulse method, and the density quantities, ρ, which were determined using the hydrostatic weight procedure based on the relationship β = u{sup -2}ρ{sup -1}. It is shown that the coefficients of the temperature dependencies for the compressibility and density of the upper and lower equilibrium phases have opposite signs because of the superposition of the intensity of the thermal motion of the ions and the change in the composition of the phases. The differences, Δβ and Δρ, in the magnitudes of the compressibility and density for the equilibrium phases decrease with temperature elevation. The temperature dependencies of the compressibility and density difference are described using the empirical equations Δβ ∼ (T{sub c}-T){sup 0.438} and Δρ ∼ (T{sub c}-T){sup 0.439}.

Preliminary safety equipment list for Tank 241-C-106 Manipulator Retrieval System, Project W-340

International Nuclear Information System (INIS)

Guthrie, R.L.

1994-01-01

This document identifies the anticipated safety classification of the estimated major subsystems, based on the projected major functions, that will be used as guidance for the development of the conceptual design of the Manipulator Retrieval System for Tank 241-C-106. This document is intended to be updated as the design of the Manipulator Retrieval System evolves through the conceptual and definitive design phases. The Manipulator Retrieval System is to be capable of removing the hardened sludge heel at the bottom of single shell Tank 241-C-106 and to perform an overall clean out of the tank that leaves a maximum of 360 ft 3 (TPA milestone M-45-00). The thickness of the heel prior to initiation of waste retrieval with the Manipulator Retrieval System is estimated to be 1- to 2-ft. The Manipulator Retrieval System is currently in the pre-conceptual phase with no definitive systems or subsystems. The anticipated retrieval functions for the Manipulator Retrieval System is based on Table 6-2 of WHC-SD-W340-ES-001, Rev. 1. Projected equipment to accomplish these functions were based on the following systems and equipment: Rotary Mode Core Sampling Equipment (WHC-SD-WM-SEL-032); Light Duty Utility Arm System Equipment (WHC-SD-WM-SEL-034); Single Shell Tanks Equipment (WHC-SD-WM-SEL-020)

Integral Monitored Retrievable Storage (MRS) Facility conceptual design report

International Nuclear Information System (INIS)

1985-09-01

This document, Volume 5 Book 1, contains cost estimate summaries for a monitored retrievable storage (MRS) facility. The cost estimate is based on the engineering performed during the conceptual design phase of the MRS Facility project

DNABIT Compress – Genome compression algorithm

OpenAIRE

Rajarajeswari, Pothuraju; Apparao, Allam

2011-01-01

Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, “DNABIT Compress” for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our ...

Effect of martensitic phase transformation on the hardening behavior and texture evolution in a 304L stainless steel under compression at liquid nitrogen temperature

Energy Technology Data Exchange (ETDEWEB)

Cakmak, Ercan [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Vogel, Sven C. [Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Choo, Hahn, E-mail: hchoo@utk.edu [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States)

2014-01-01

The martensitic phase transformation behavior and its relations with the macroscopic hardening rate and the evolutions in the crystallographic texture of the constituent phases were studied for a 304L stainless steel that exhibits the transformation induced plasticity (TRIP) phenomenon. Time-of-flight neutron diffraction was used to measure the evolutions of phase fractions and texture in terms of pole figures as a function of the applied compressive strain at the liquid nitrogen temperature (77 K). The phase transformation analyses show that the hcp-martensite phase fraction reaches a significant level of about 22 wt% at 15% applied strain and remains constant. The bcc-martensite phase fraction increases continuously with the deformation that correlates well with the macroscopic hardening behavior. Furthermore, the texture analyses show that transformation has dominant effect on the bcc-martensite texture evolution with little influence from subsequent plastic deformation at current testing conditions.

Effect of martensitic phase transformation on the hardening behavior and texture evolution in a 304L stainless steel under compression at liquid nitrogen temperature

International Nuclear Information System (INIS)

Cakmak, Ercan; Vogel, Sven C.; Choo, Hahn

2014-01-01

The martensitic phase transformation behavior and its relations with the macroscopic hardening rate and the evolutions in the crystallographic texture of the constituent phases were studied for a 304L stainless steel that exhibits the transformation induced plasticity (TRIP) phenomenon. Time-of-flight neutron diffraction was used to measure the evolutions of phase fractions and texture in terms of pole figures as a function of the applied compressive strain at the liquid nitrogen temperature (77 K). The phase transformation analyses show that the hcp-martensite phase fraction reaches a significant level of about 22 wt% at 15% applied strain and remains constant. The bcc-martensite phase fraction increases continuously with the deformation that correlates well with the macroscopic hardening behavior. Furthermore, the texture analyses show that transformation has dominant effect on the bcc-martensite texture evolution with little influence from subsequent plastic deformation at current testing conditions

Fragment separator momentum compression schemes

Energy Technology Data Exchange (ETDEWEB)

Bandura, Laura, E-mail: bandura@anl.gov [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); National Superconducting Cyclotron Lab, Michigan State University, 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Erdelyi, Bela [Argonne National Laboratory, Argonne, IL 60439 (United States); Northern Illinois University, DeKalb, IL 60115 (United States); Hausmann, Marc [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Kubo, Toshiyuki [RIKEN Nishina Center, RIKEN, Wako (Japan); Nolen, Jerry [Argonne National Laboratory, Argonne, IL 60439 (United States); Portillo, Mauricio [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Sherrill, Bradley M. [National Superconducting Cyclotron Lab, Michigan State University, 1 Cyclotron, East Lansing, MI 48824-1321 (United States)

2011-07-21

We present a scheme to use a fragment separator and profiled energy degraders to transfer longitudinal phase space into transverse phase space while maintaining achromatic beam transport. The first order beam optics theory of the method is presented and the consequent enlargement of the transverse phase space is discussed. An interesting consequence of the technique is that the first order mass resolving power of the system is determined by the first dispersive section up to the energy degrader, independent of whether or not momentum compression is used. The fragment separator at the Facility for Rare Isotope Beams is a specific application of this technique and is described along with simulations by the code COSY INFINITY.

Fragment separator momentum compression schemes

International Nuclear Information System (INIS)

Bandura, Laura; Erdelyi, Bela; Hausmann, Marc; Kubo, Toshiyuki; Nolen, Jerry; Portillo, Mauricio; Sherrill, Bradley M.

2011-01-01

We present a scheme to use a fragment separator and profiled energy degraders to transfer longitudinal phase space into transverse phase space while maintaining achromatic beam transport. The first order beam optics theory of the method is presented and the consequent enlargement of the transverse phase space is discussed. An interesting consequence of the technique is that the first order mass resolving power of the system is determined by the first dispersive section up to the energy degrader, independent of whether or not momentum compression is used. The fragment separator at the Facility for Rare Isotope Beams is a specific application of this technique and is described along with simulations by the code COSY INFINITY.

Accelerated three-dimensional cine phase contrast imaging using randomly undersampled echo planar imaging with compressed sensing reconstruction.

Science.gov (United States)

Basha, Tamer A; Akçakaya, Mehmet; Goddu, Beth; Berg, Sophie; Nezafat, Reza

2015-01-01

The aim of this study was to implement and evaluate an accelerated three-dimensional (3D) cine phase contrast MRI sequence by combining a randomly sampled 3D k-space acquisition sequence with an echo planar imaging (EPI) readout. An accelerated 3D cine phase contrast MRI sequence was implemented by combining EPI readout with randomly undersampled 3D k-space data suitable for compressed sensing (CS) reconstruction. The undersampled data were then reconstructed using low-dimensional structural self-learning and thresholding (LOST). 3D phase contrast MRI was acquired in 11 healthy adults using an overall acceleration of 7 (EPI factor of 3 and CS rate of 3). For comparison, a single two-dimensional (2D) cine phase contrast scan was also performed with sensitivity encoding (SENSE) rate 2 and approximately at the level of the pulmonary artery bifurcation. The stroke volume and mean velocity in both the ascending and descending aorta were measured and compared between two sequences using Bland-Altman plots. An average scan time of 3 min and 30 s, corresponding to an acceleration rate of 7, was achieved for 3D cine phase contrast scan with one direction flow encoding, voxel size of 2 × 2 × 3 mm(3) , foot-head coverage of 6 cm and temporal resolution of 30 ms. The mean velocity and stroke volume in both the ascending and descending aorta were statistically equivalent between the proposed 3D sequence and the standard 2D cine phase contrast sequence. The combination of EPI with a randomly undersampled 3D k-space sampling sequence using LOST reconstruction allows a seven-fold reduction in scan time of 3D cine phase contrast MRI without compromising blood flow quantification. Copyright © 2014 John Wiley & Sons, Ltd.

A Fast, Background-Independent Retrieval Strategy for Color Image Databases

National Research Council Canada - National Science Library

Das, M; Draper, B. A; Lim, W. J; Manmatha, R; Riseman, E. M

1996-01-01

We describe an interactive, multi-phase color-based image retrieval system which is capable of identifying query objects specified by the user in an image in the presence of significant, interfering backgrounds...

GPM Mission Gridded Text Products Providing Surface Precipitation Retrievals

Science.gov (United States)

Stocker, Erich Franz; Kelley, Owen; Huffman, George; Kummerow, Christian

2015-04-01

constellation satellites. Both of these gridded products are generated for a .25 degree x .25 degree hourly grid, which are packaged into daily ASCII files that can downloaded from the PPS FTP site. To reduce the download size, the files are compressed using the gzip utility. This paper will focus on presenting high-level details about the gridded text product being generated from the instruments on the GPM core satellite. But summary information will also be presented about the partner radiometer gridded product. All retrievals for the partner radiometer are done using the GPROF2014 algorithm using as input the PPS generated inter-calibrated 1C product for the radiometer.

Selective memory retrieval can impair and improve retrieval of other memories.

Science.gov (United States)

Bäuml, Karl-Heinz T; Samenieh, Anuscheh

2012-03-01

Research from the past decades has shown that retrieval of a specific memory (e.g., retrieving part of a previous vacation) typically attenuates retrieval of other memories (e.g., memories for other details of the event), causing retrieval-induced forgetting. More recently, however, it has been shown that retrieval can both attenuate and aid recall of other memories (K.-H. T. Bäuml & A. Samenieh, 2010). To identify the circumstances under which retrieval aids recall, the authors examined retrieval dynamics in listwise directed forgetting, context-dependent forgetting, proactive interference, and in the absence of any induced memory impairment. They found beneficial effects of selective retrieval in listwise directed forgetting and context-dependent forgetting but detrimental effects in all the other conditions. Because context-dependent forgetting and listwise directed forgetting arguably reflect impaired context access, the results suggest that memory retrieval aids recall of memories that are subject to impaired context access but attenuates recall in the absence of such circumstances. The findings are consistent with a 2-factor account of memory retrieval and suggest the existence of 2 faces of memory retrieval. 2012 APA, all rights reserved

Foreign Body Retrieval

Medline Plus

Full Text Available ... Physician Resources Professions Site Index A-Z Foreign Body Retrieval Foreign body retrieval is the removal of ... foreign body detection and removal? What is Foreign Body Retrieval? Foreign body retrieval involves the removal of ...

The role of retrieval mode and retrieval orientation in retrieval practice: insights from comparing recognition memory testing formats and restudying.

Science.gov (United States)

Gao, Chuanji; Rosburg, Timm; Hou, Mingzhu; Li, Bingbing; Xiao, Xin; Guo, Chunyan

2016-12-01

The effectiveness of retrieval practice for aiding long-term memory, referred to as the testing effect, has been widely demonstrated. However, the specific neurocognitive mechanisms underlying this phenomenon remain unclear. In the present study, we sought to explore the role of pre-retrieval processes at initial testing on later recognition performance by using event-related potentials (ERPs). Subjects studied two lists of words (Chinese characters) and then performed a recognition task or a source memory task, or restudied the word lists. At the end of the experiment, subjects received a final recognition test based on the remember-know paradigm. Behaviorally, initial testing (active retrieval) enhanced memory retention relative to restudying (passive retrieval). The retrieval mode at initial testing was indexed by more positive-going ERPs for unstudied items in the active-retrieval tasks than in passive retrieval from 300 to 900 ms. Follow-up analyses showed that the magnitude of the early ERP retrieval mode effect (300-500 ms) was predictive of the behavioral testing effect later on. In addition, the ERPs for correctly rejected new items during initial testing differed between the two active-retrieval tasks from 500 to 900 ms, and this ERP retrieval orientation effect predicted differential behavioral testing gains between the two active-retrieval conditions. Our findings confirm that initial testing promotes later retrieval relative to restudying, and they further suggest that adopting pre-retrieval processing in the forms of retrieval mode and retrieval orientation might contribute to these memory enhancements.

Rapid freezing of water under dynamic compression

Science.gov (United States)

Myint, Philip C.; Belof, Jonathan L.

2018-06-01

Understanding the behavior of materials at extreme pressures is a central issue in fields like aerodynamics, astronomy, and geology, as well as for advancing technological grand challenges such as inertial confinement fusion. Dynamic compression experiments to probe high-pressure states often encounter rapid phase transitions that may cause the materials to behave in unexpected ways, and understanding the kinetics of these phase transitions remains an area of great interest. In this review, we examine experimental and theoretical/computational efforts to study the freezing kinetics of water to a high-pressure solid phase known as ice VII. We first present a detailed analysis of dynamic compression experiments in which water has been observed to freeze on sub-microsecond time scales to ice VII. This is followed by a discussion of the limitations of currently available molecular and continuum simulation methods in modeling these experiments. We then describe how our phase transition kinetics models, which are based on classical nucleation theory, provide a more physics-based framework that overcomes some of these limitations. Finally, we give suggestions on future experimental and modeling work on the liquid–ice VII transition, including an outline of the development of a predictive multiscale model in which molecular and continuum simulations are intimately coupled.

Elastic behavior of MFI-type zeolites: 3 – Compressibility of silicalite and mutinaite

International Nuclear Information System (INIS)

Quartieri, Simona; Arletti, Rossella; Vezzalini, Giovanna; Di Renzo, Francesco; Dmitriev, Vladimir

2012-01-01

We report the results of an in-situ synchrotron X-ray powder diffraction study – performed using silicone oil as “non-penetrating” pressure transmitting medium – of the elastic behavior of three zeolites with MFI-type framework: the natural zeolite mutinaite and two silicalites (labeled A and B) synthesized under different conditions. While in mutinaite no symmetry change is observed as a function of pressure, a phase transition from monoclinic (P2 1 /n) to orthorhombic (Pnma) symmetry occurs at about 1.0 GPa in the silicalite samples. This phase transition is irreversible upon decompression. The second order bulk moduli of silicalite A and silicalite B, calculated after the fulfillment of the phase transition, are: K 0 =18.2(2) and K 0 =14.3 (2) GPa, respectively. These values makes silicalite the most compressible zeolite among those up to now studied in silicone oil. The structural deformations induced by HP in silicalite A were investigated by means of complete Rietveld structural refinements, before and after the phase transition, at P amb and 0.9 GPa, respectively. The elastic behaviors of the three MFI-type zeolites here investigated were compared with those of Na-ZSM-5 and H-ZSM-5, studied in similar experimental conditions: the two silicalites – which are the phases with the highest Si/Al ratios and hence the lowest extraframework contents – show the highest compressibility. On the contrary, the most rigid material is mutinaite, which has a very complex extraframework composition characterized by a high number of cations and water molecules. - Graphical abstract: High-pressure behavior of silicalite compressed in silicone oil: projection of the structure along the [0 1 0] direction at Pamb(a), 0.9 GPa (b). (c) Comparison of the unit-cell volume variations as a function of pressure for mutinaite, H-ZSM5, Na-ZSM5, silicalite A, and silicalite B compressed in silicone oil. Highlights: ► X-ray powder diffraction study of silicalite and mutinaite

1,500 IU human chorionic gonadotropin administered at oocyte retrieval rescues the luteal phase when gonadotropin-releasing hormone agonist is used for ovulation induction

DEFF Research Database (Denmark)

Humaidan, Peter; Bredkjær, Helle Ejdrup; Westergaard, Lars Grabow

2009-01-01

OBJECTIVE: To prospectively assess the reproductive outcome with a small bolus of hCG administered on the day of oocyte retrieval after ovulation induction with a GnRH agonist (GnRHa). DESIGN: Prospective, randomized trial. SETTING: Three hospital-based IVF clinics. PATIENT(S): Three hundred five...... IVF/intracytoplasmic sperm injection patients after a GnRH antagonist protocol. INTERVENTION(S): Ovulation induction was performed with either 10,000 IU hCG or 0.5 mg GnRHa (buserelin) supplemented with 1,500 IU hCG on the day of oocyte retrieval. MAIN OUTCOME MEASURE(S): Reproductive outcome...... bolus of hCG in the GnRHa group secured the luteal phase, resulting in a comparable reproductive outcome in the two groups. However, a nonsignificant difference of 7% in delivery rates justifies further studies to refine the use of GnRHa for ovulation induction....

n-Gram-Based Text Compression

Science.gov (United States)

Duong, Hieu N.; Snasel, Vaclav

2016-01-01

We propose an efficient method for compressing Vietnamese text using n-gram dictionaries. It has a significant compression ratio in comparison with those of state-of-the-art methods on the same dataset. Given a text, first, the proposed method splits it into n-grams and then encodes them based on n-gram dictionaries. In the encoding phase, we use a sliding window with a size that ranges from bigram to five grams to obtain the best encoding stream. Each n-gram is encoded by two to four bytes accordingly based on its corresponding n-gram dictionary. We collected 2.5 GB text corpus from some Vietnamese news agencies to build n-gram dictionaries from unigram to five grams and achieve dictionaries with a size of 12 GB in total. In order to evaluate our method, we collected a testing set of 10 different text files with different sizes. The experimental results indicate that our method achieves compression ratio around 90% and outperforms state-of-the-art methods. PMID:27965708

n-Gram-Based Text Compression

Directory of Open Access Journals (Sweden)

Vu H. Nguyen

2016-01-01

Full Text Available We propose an efficient method for compressing Vietnamese text using n-gram dictionaries. It has a significant compression ratio in comparison with those of state-of-the-art methods on the same dataset. Given a text, first, the proposed method splits it into n-grams and then encodes them based on n-gram dictionaries. In the encoding phase, we use a sliding window with a size that ranges from bigram to five grams to obtain the best encoding stream. Each n-gram is encoded by two to four bytes accordingly based on its corresponding n-gram dictionary. We collected 2.5 GB text corpus from some Vietnamese news agencies to build n-gram dictionaries from unigram to five grams and achieve dictionaries with a size of 12 GB in total. In order to evaluate our method, we collected a testing set of 10 different text files with different sizes. The experimental results indicate that our method achieves compression ratio around 90% and outperforms state-of-the-art methods.

Multi-sensor measurements of mixed-phase clouds above Greenland

Science.gov (United States)

Stillwell, Robert A.; Shupe, Matthew D.; Thayer, Jeffrey P.; Neely, Ryan R.; Turner, David D.

2018-04-01

Liquid-only and mixed-phase clouds in the Arctic strongly affect the regional surface energy and ice mass budgets, yet much remains unknown about the nature of these clouds due to the lack of intensive measurements. Lidar measurements of these clouds are challenged by very large signal dynamic range, which makes even seemingly simple tasks, such as thermodynamic phase classification, difficult. This work focuses on a set of measurements made by the Clouds Aerosol Polarization and Backscatter Lidar at Summit, Greenland and its retrieval algorithms, which use both analog and photon counting as well as orthogonal and non-orthogonal polarization retrievals to extend dynamic range and improve overall measurement quality and quantity. Presented here is an algorithm for cloud parameter retrievals that leverages enhanced dynamic range retrievals to classify mixed-phase clouds. This best guess retrieval is compared to co-located instruments for validation.

Impact of monaural frequency compression on binaural fusion at the brainstem level.

Science.gov (United States)

Klauke, Isabelle; Kohl, Manuel C; Hannemann, Ronny; Kornagel, Ulrich; Strauss, Daniel J; Corona-Strauss, Farah I

2015-08-01

A classical objective measure for binaural fusion at the brainstem level is the so-called β-wave of the binaural interaction component (BIC) in the auditory brainstem response (ABR). However, in some cases it appeared that a reliable detection of this component still remains a challenge. In this study, we investigate the wavelet phase synchronization stability (WPSS) of ABR data for the analysis of binaural fusion and compare it to the BIC. In particular, we examine the impact of monaural nonlinear frequency compression on binaural fusion. As the auditory system is tonotopically organized, an interaural frequency mismatch caused by monaural frequency compression could negatively effect binaural fusion. In this study, only few subjects showed a detectable β-wave and in most cases only for low ITDs. However, we present a novel objective measure for binaural fusion that outperforms the current state-of-the-art technique (BIC): the WPSS analysis showed a significant difference between the phase stability of the sum of the monaurally evoked responses and the phase stability of the binaurally evoked ABR. This difference could be an indicator for binaural fusion in the brainstem. Furthermore, we observed that monaural frequency compression could indeed effect binaural fusion, as the WPSS results for this condition vary strongly from the results obtained without frequency compression.

Retrieval of fluidizable radioactive wastes from storage facilities

International Nuclear Information System (INIS)

2006-08-01

This report provides guidance for strategic planning and implementation of resuspension and retrieval of stored fluid or fluidizable radioactive wastes. The potential risks associated with preparation and realization of these processes are included in the report, and lessons learned from previous applications are highlighted. Technological procedures and equipment used in various countries for resuspension and remobilization of stored fluidizable radioactive wastes are described in the attached annexes as potential options. Waste retrieval is a maturing technology of major importance now that Member States are moving forward in the responsible management of wastes by removal to safe interim storage or disposal. Retrieval of fluidizable wastes is a four-phase operation: (1) access to the waste, (2) mobilize the waste, (3) remove the waste; and (4) transfer the waste.This report divides successful retrieval of radioactive waste into two areas. The first area applies the concept of the waste retrieval as being the final component of a systematic process of old waste management. It also encompasses characterization as it applies to waste retrieval and downstream processes, including acceptance of wastes for treatment, conditioning, storage or disposal. It should be in conformity with national policy, as well as complying with international safety standards and environmental agreements. The second area of the report focuses on implementation of waste retrieval in a wide range of scenarios and using a wide range of retrieval approaches, equipment and technologies. Technical processes are further explained as part of the experience gained in advanced countries on the subject. A set of detailed retrieval technology descriptions by country is included as Annexes to this report. Thirteen experts from seven Member States that previously implemented, or have planned for the near future, significant resuspension and remobilization operations were involved in the preparation of

The astronaut and the banana peel: An EVA retriever scenario

Science.gov (United States)

Shapiro, Daniel G.

1989-01-01

To prepare for the problem of accidents in Space Station activities, the Extravehicular Activity Retriever (EVAR) robot is being constructed, whose purpose is to retrieve astronauts and tools that float free of the Space Station. Advanced Decision Systems is at the beginning of a project to develop research software capable of guiding EVAR through the retrieval process. This involves addressing problems in machine vision, dexterous manipulation, real time construction of programs via speech input, and reactive execution of plans despite the mishaps and unexpected conditions that arise in uncontrolled domains. The problem analysis phase of this work is presented. An EVAR scenario is used to elucidate major domain and technical problems. An overview of the technical approach to prototyping an EVAR system is also presented.

Two Independent Mushroom Body Output Circuits Retrieve the Six Discrete Components of Drosophila Aversive Memory

Directory of Open Access Journals (Sweden)

Emna Bouzaiane

2015-05-01

Full Text Available Understanding how the various memory components are encoded and how they interact to guide behavior requires knowledge of the underlying neural circuits. Currently, aversive olfactory memory in Drosophila is behaviorally subdivided into four discrete phases. Among these, short- and long-term memories rely, respectively, on the γ and α/β Kenyon cells (KCs, two distinct subsets of the ∼2,000 neurons in the mushroom body (MB. Whereas V2 efferent neurons retrieve memory from α/β KCs, the neurons that retrieve short-term memory are unknown. We identified a specific pair of MB efferent neurons, named M6, that retrieve memory from γ KCs. Moreover, our network analysis revealed that six discrete memory phases actually exist, three of which have been conflated in the past. At each time point, two distinct memory components separately recruit either V2 or M6 output pathways. Memory retrieval thus features a dramatic convergence from KCs to MB efferent neurons.

Changes in the modulation of brain activity during context encoding vs. context retrieval across the adult lifespan.

Science.gov (United States)

Ankudowich, E; Pasvanis, S; Rajah, M N

2016-10-01

Age-related deficits in context memory may arise from neural changes underlying both encoding and retrieval of context information. Although age-related functional changes in the brain regions supporting context memory begin at midlife, little is known about the functional changes with age that support context memory encoding and retrieval across the adult lifespan. We investigated how age-related functional changes support context memory across the adult lifespan by assessing linear changes with age during successful context encoding and retrieval. Using functional magnetic resonance imaging (fMRI), we compared young, middle-aged and older adults during both encoding and retrieval of spatial and temporal details of faces. Multivariate behavioral partial least squares (B-PLS) analysis of fMRI data identified a pattern of whole-brain activity that correlated with a linear age term and a pattern of whole-brain activity that was associated with an age-by-memory phase (encoding vs. retrieval) interaction. Further investigation of this latter effect identified three main findings: 1) reduced phase-related modulation in bilateral fusiform gyrus, left superior/anterior frontal gyrus and right inferior frontal gyrus that started at midlife and continued to older age, 2) reduced phase-related modulation in bilateral inferior parietal lobule that occurred only in older age, and 3) changes in phase-related modulation in older but not younger adults in left middle frontal gyrus and bilateral parahippocampal gyrus that was indicative of age-related over-recruitment. We conclude that age-related reductions in context memory arise in midlife and are related to changes in perceptual recollection and changes in fronto-parietal retrieval monitoring. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

Revising the lower statistical limit of x-ray grating-based phase-contrast computed tomography.

Science.gov (United States)

Marschner, Mathias; Birnbacher, Lorenz; Willner, Marian; Chabior, Michael; Herzen, Julia; Noël, Peter B; Pfeiffer, Franz

2017-01-01

Phase-contrast x-ray computed tomography (PCCT) is currently investigated as an interesting extension of conventional CT, providing high soft-tissue contrast even if examining weakly absorbing specimen. Until now, the potential for dose reduction was thought to be limited compared to attenuation CT, since meaningful phase retrieval fails for scans with very low photon counts when using the conventional phase retrieval method via phase stepping. In this work, we examine the statistical behaviour of the reverse projection method, an alternative phase retrieval approach and compare the results to the conventional phase retrieval technique. We investigate the noise levels in the projections as well as the image quality and quantitative accuracy of the reconstructed tomographic volumes. The results of our study show that this method performs better in a low-dose scenario than the conventional phase retrieval approach, resulting in lower noise levels, enhanced image quality and more accurate quantitative values. Overall, we demonstrate that the lower statistical limit of the phase stepping procedure as proposed by recent literature does not apply to this alternative phase retrieval technique. However, further development is necessary to overcome experimental challenges posed by this method which would enable mainstream or even clinical application of PCCT.

A high compression crystal growth system

International Nuclear Information System (INIS)

Nieman, H.F.; Walton, A.A.; Powell, B.M.; Dolling, G.

1980-01-01

This report describes the construction and operating procedure for a high compression crystal growth system, capable of growing single crystals from the fluid phase over the temperature range of 4.2 K to 300 K, at pressures up to 900 MPa. Some experimental results obtained with the system are given for solid β-nitrogen. (auth)

Feasibility study: Assess the feasibility of siting a monitored retrievable storage facility

International Nuclear Information System (INIS)

King, J.W.

1993-01-01

The purpose of phase one of this study are: To understand the waste management system and a monitored retrievable storage facility; and to determine whether the applicant has real interest in pursuing the feasibility assessment process. Contents of this report are: Generating electric power; facts about exposure to radiation; handling storage, and transportation techniques; description of a proposed monitored retrievable storage facility; and benefits to be received by host jurisdiction

Solid - solid and solid - liquid phase transitions of iron and iron alloys under laser shock compression

Science.gov (United States)

Harmand, M.; Krygier, A.; Appel, K.; Galtier, E.; Hartley, N.; Konopkova, Z.; Lee, H. J.; McBride, E. E.; Miyanishi, K.; Nagler, B.; Nemausat, R.; Vinci, T.; Zhu, D.; Ozaki, N.; Fiquet, G.

2017-12-01

An accurate knowledge of the properties of iron and iron alloys at high pressures and temperatures is crucial for understanding and modelling planetary interiors. While Earth-size and Super-Earth Exoplanets are being discovered in increasingly large numbers, access to detailed information on liquid properties, melting curves and even solid phases of iron and iron at the pressures and temperatures of their interiors is still strongly limited. In this context, XFEL sources coupled with high-energy lasers afford unique opportunities to measure microscopic structural properties at far extreme conditions. Also the achievable time resolution allows the shock history and phase transition mechanisms to be followed during laser compression, improving our understanding of the high pressure and high strain experiments. Here we present recent studies devoted to investigate the solid-solid and solid-liquid transition in laser-shocked iron and iron alloys (Fe-Si, Fe-C and Fe-O alloys) using X-ray diffraction and X-ray diffuse scattering. Experiment were performed at the MEC end-station of the LCLS facility at SLAC (USA). Detection of the diffuse scattering allowed the identification of the first liquid peak position along the Hugoniot, up to 4 Mbar. The time resolution shows ultrafast (between several tens and several hundreds of picoseconds) solid-solid and solid-liquid phase transitions. Future developments at XFEL facilities will enable detailed studies of the solid and liquid structures of iron and iron alloys as well as out-of-Hugoniot studies.

A multiphase compressible model for the simulation of multiphase flows

International Nuclear Information System (INIS)

Caltagirone, J.P.; Vincent, St.; Caruyer, C.

2011-01-01

A compressible model able to manage incompressible two-phase flows as well as compressible motions is proposed. After a presentation of the multiphase compressible concept, the new model and related numerical methods are detailed on fixed structured grids. The presented model is a 1-fluid model with a reformulated mass conservation equation which takes into account the effects of compressibility. The coupling between pressure and flow velocity is ensured by introducing mass conservation terms in the momentum and energy equations. The numerical model is then validated with four test cases involving the compression of an air bubble by water, the liquid injection in a closed cavity filled with air, a bubble subjected to an ultrasound field and finally the oscillations of a deformed air bubble in melted steel. The numerical results are compared with analytical results and convergence orders in space are provided. (authors)

Binary multiplexing and the phase-retrieval problem

International Nuclear Information System (INIS)

Ghiglia, D.C.

1982-01-01

A binary-mask multiplexing method is developed that provides a means of recovering phase information unambiguously from measurements of the modulus of masked complex waves in the object and image planes, respectively. The technique is developed from Fourier-transform theory and combinatorial analysis and is derived for both the continuous case (optical-digital-hybrid implementation) and the totally discrete case (digital computer simulation). Computer simulations provide unambiguous recovery of phase information and indicate that the matrix equations are reasonably well conditioned for cases of practical significance

Comparative data compression techniques and multi-compression results

International Nuclear Information System (INIS)

Hasan, M R; Ibrahimy, M I; Motakabber, S M A; Ferdaus, M M; Khan, M N H

2013-01-01

Data compression is very necessary in business data processing, because of the cost savings that it offers and the large volume of data manipulated in many business applications. It is a method or system for transmitting a digital image (i.e., an array of pixels) from a digital data source to a digital data receiver. More the size of the data be smaller, it provides better transmission speed and saves time. In this communication, we always want to transmit data efficiently and noise freely. This paper will provide some compression techniques for lossless text type data compression and comparative result of multiple and single compression, that will help to find out better compression output and to develop compression algorithms

Strain mapping of LED devices by dark-field inline electron holography: Comparison between deterministic and iterative phase retrieval approaches

Energy Technology Data Exchange (ETDEWEB)

Song, Kyung; Shin, Ga-Young; Kim, Jong Kyu [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), San 31 Hyoja-dong, Nam-gu, Pohang 790-784 (Korea, Republic of); Oh, Sang Ho, E-mail: shoh@postech.ac.kr [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), San 31 Hyoja-dong, Nam-gu, Pohang 790-784 (Korea, Republic of); Koch, Christoph T. [Institute for Experimental Physics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm (Germany)

2013-04-15

Dark-field inline electron holography has recently been established as a convenient method to map strain in semiconductor devices, combining high precision, low noise, sub-nm spatial resolution and fields-of-view larger than 1 μm. Here we compare two approaches to reconstruct the geometric phase from a transmission electron microscopy dark-field focal series and their effects on the strain measurement: the transport-of-intensity-equation (TIE) and a flux-preserving iterative approach. For this task, we used a GaN-based light emitting diode with a highly complex heterostructure as a model system. While the TIE relies on 3 images only but requires the optimization of two free parameters (defocus step and low-limit cut-off frequency), the iterative reconstruction algorithm involves no adjustable parameters and uses images recorded at 9 different planes of focus with quadratically increasing defocus values. Optimum parameters for the TIE-reconstruction could be identified. However, the iterative phase retrieval approach yields the strain values that agree best with the expected strain levels and provides also higher spatial resolution.

Polarimetric rainfall retrieval from a C-Band weather radar in a tropical environment (The Philippines)

Science.gov (United States)

Crisologo, I.; Vulpiani, G.; Abon, C. C.; David, C. P. C.; Bronstert, A.; Heistermann, Maik

2014-11-01

We evaluated the potential of polarimetric rainfall retrieval methods for the Tagaytay C-Band weather radar in the Philippines. For this purpose, we combined a method for fuzzy echo classification, an approach to extract and reconstruct the differential propagation phase, Φ DP , and a polarimetric self-consistency approach to calibrate horizontal and differential reflectivity. The reconstructed Φ DP was used to estimate path-integrated attenuation and to retrieve the specific differential phase, K DP . All related algorithms were transparently implemented in the Open Source radar processing software wradlib. Rainfall was then estimated from different variables: from re-calibrated reflectivity, from re-calibrated reflectivity that has been corrected for path-integrated attenuation, from the specific differential phase, and from a combination of reflectivity and specific differential phase. As an additional benchmark, rainfall was estimated by interpolating the rainfall observed by rain gauges. We evaluated the rainfall products for daily and hourly accumulations. For this purpose, we used observations of 16 rain gauges from a five-month period in the 2012 wet season. It turned out that the retrieval of rainfall from K DP substantially improved the rainfall estimation at both daily and hourly time scales. The measurement of reflectivity apparently was impaired by severe miscalibration while K DP was immune to such effects. Daily accumulations of rainfall retrieved from K DP showed a very low estimation bias and small random errors. Random scatter was, though, strongly present in hourly accumulations.

Retrieval-Based Learning: Positive Effects of Retrieval Practice in Elementary School Children

Directory of Open Access Journals (Sweden)

Jeffrey D. Karpicke

2016-03-01

Full Text Available A wealth of research has demonstrated that practicing retrieval is a powerful way to enhance learning. However, nearly all prior research has examined retrieval practice with college students. Little is known about retrieval practice in children, and even less is known about possible individual differences in retrieval practice. In three experiments, 88 children (mean age 10 years studied a list of words and either restudied the items or practiced retrieving them. They then took a final free recall test (Experiments 1 and 2 or recognition test (Experiment 3. In all experiments, children showed robust retrieval practice effects. Although a range of individual differences in reading comprehension and processing speed were observed among these children, the benefits of retrieval practice were independent of these factors. The results contribute to the growing body of research supporting the mnemonic benefits of retrieval practice and provide preliminary evidence that practicing retrieval may be an effective learning strategy for children with varying levels of reading comprehension and processing speed.

smallWig: parallel compression of RNA-seq WIG files.

Science.gov (United States)

Wang, Zhiying; Weissman, Tsachy; Milenkovic, Olgica

2016-01-15

this claim, we performed a statistical analysis of expression data in different transform domains and developed accompanying entropy coding methods that bridge the gap between theoretical and practical WIG file compression rates. We tested different variants of the smallWig compression algorithm on a number of integer-and real- (floating point) valued RNA-seq WIG files generated by the ENCODE project. The results reveal that, on average, smallWig offers 18-fold compression rate improvements, up to 2.5-fold compression time improvements, and 1.5-fold decompression time improvements when compared with bigWig. On the tested files, the memory usage of the algorithm never exceeded 90 KB. When more elaborate context mixing compressors were used within smallWig, the obtained compression rates were as much as 23 times better than those of bigWig. For smallWig used in the random query mode, which also supports retrieval of the summary statistics, an overhead in the compression rate of roughly 3-17% was introduced depending on the chosen system parameters. An increase in encoding and decoding time of 30% and 55% represents an additional performance loss caused by enabling random data access. We also implemented smallWig using multi-processor programming. This parallelization feature decreases the encoding delay 2-3.4 times compared with that of a single-processor implementation, with the number of processors used ranging from 2 to 8; in the same parameter regime, the decoding delay decreased 2-5.2 times. The smallWig software can be downloaded from: http://stanford.edu/~zhiyingw/smallWig/smallwig.html, http://publish.illinois.edu/milenkovic/, http://web.stanford.edu/~tsachy/. zhiyingw@stanford.edu Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Economics of compressed air energy storage employing thermal energy storage

Energy Technology Data Exchange (ETDEWEB)

Schulte, S.C.; Reilly, R.W.

1979-11-01

The approach taken in this study is to adopt system design and capital cost estimates from three independent CAES studies (eight total designs) and, by supplying a common set of fuel/energy costs and economic assumptions in conjunction with a common methodology, to arrive at a series of levelized energy costs over the system's lifetime. In addition, some analyses are provided to gauge the sensitivity of these levelized energy costs to fuel and compression energy costs and to system capacity factors. The systems chosen for comparison are of four generic types: conventional CAES, hybrid CAES, adiabatic CAES, and an advanced-design gas turbine (GT). In conventional CAES systems the heat of compression generated during the storage operation is rejected to the environment, and later, during the energy-generation phase, turbine fuel must be burned to reheat the compressed air. In the hybrid systems some of the heat of compression is stored and reapplied later during the generation phase, thereby reducing turbine fuel requirements. The adiabatic systems store adequate thermal energy to eliminate the need for turbine fuel entirely. The gas turbine is included within the report for comparison purposes; it is an advanced-design turbine, one that is expected to be available by 1985.

Fault Tolerant Paradigms

Science.gov (United States)

2016-02-26

ln d ) -time in that case.14 We prove Theorem 7 by following the generic compressive phase retrieval recipe presented in [24]. Let C ∈ Cm×d be any...retrieval, available online: arXiv:1312.0158. [20] S. Cook , The P versus NP problem, available online: http://www.claymath.org/millennium/PvsNP

Compression of fiber supercontinuum pulses to the Fourier-limit in a high-numerical-aperture focus

DEFF Research Database (Denmark)

Tu, Haohua; Liu, Yuan; Turchinovich, Dmitry

2011-01-01

A multiphoton intrapulse interference phase scan (MIIPS) adaptively and automatically compensates the combined phase distortion from a fiber supercontinuum source, a spatial light modulator pulse shaper, and a high-NA microscope objective, allowing Fourier-transform-limited compression of the sup......A multiphoton intrapulse interference phase scan (MIIPS) adaptively and automatically compensates the combined phase distortion from a fiber supercontinuum source, a spatial light modulator pulse shaper, and a high-NA microscope objective, allowing Fourier-transform-limited compression...... power of 18–70mW, and a repetition rate of 76MHz, permitting the application of this source to nonlinear optical microscopy and coherently controlled microspectroscopy....

Bayesian aerosol retrieval algorithm for MODIS AOD retrieval over land

Science.gov (United States)

Lipponen, Antti; Mielonen, Tero; Pitkänen, Mikko R. A.; Levy, Robert C.; Sawyer, Virginia R.; Romakkaniemi, Sami; Kolehmainen, Ville; Arola, Antti

2018-03-01

We have developed a Bayesian aerosol retrieval (BAR) algorithm for the retrieval of aerosol optical depth (AOD) over land from the Moderate Resolution Imaging Spectroradiometer (MODIS). In the BAR algorithm, we simultaneously retrieve all dark land pixels in a granule, utilize spatial correlation models for the unknown aerosol parameters, use a statistical prior model for the surface reflectance, and take into account the uncertainties due to fixed aerosol models. The retrieved parameters are total AOD at 0.55 µm, fine-mode fraction (FMF), and surface reflectances at four different wavelengths (0.47, 0.55, 0.64, and 2.1 µm). The accuracy of the new algorithm is evaluated by comparing the AOD retrievals to Aerosol Robotic Network (AERONET) AOD. The results show that the BAR significantly improves the accuracy of AOD retrievals over the operational Dark Target (DT) algorithm. A reduction of about 29 % in the AOD root mean square error and decrease of about 80 % in the median bias of AOD were found globally when the BAR was used instead of the DT algorithm. Furthermore, the fraction of AOD retrievals inside the ±(0.05+15 %) expected error envelope increased from 55 to 76 %. In addition to retrieving the values of AOD, FMF, and surface reflectance, the BAR also gives pixel-level posterior uncertainty estimates for the retrieved parameters. The BAR algorithm always results in physical, non-negative AOD values, and the average computation time for a single granule was less than a minute on a modern personal computer.

Memory as discrimination: a challenge to the encoding-retrieval match principle

OpenAIRE

Poirier, M.; Nairne, J. S.; Morin, C.; Zimmermann, F. G.; Koutmeridou, K.; Fowler, J.

2012-01-01

Four experiments contrasted the predictions of a general encoding-retrieval match hypothesis with those of a view claiming that the distinctiveness of the cue-target relationship is the causal factor in retrieval. In Experiments 1, 2, and 4 participants learned the relationships between 4 targets and trios of cues; in Experiment 3 there were 3 targets, each associated with a pair of cues. A learning phase was followed by a cued-recognition task where the correct target had to be identified ba...

Single exposure optically compressed imaging and visualization using random aperture coding

Energy Technology Data Exchange (ETDEWEB)

Stern, A [Electro Optical Unit, Ben Gurion University of the Negev, Beer-Sheva 84105 (Israel); Rivenson, Yair [Department of Electrical and Computer Engineering, Ben Gurion University of the Negev, Beer-Sheva 84105 (Israel); Javidi, Bahrain [Department of Electrical and Computer Engineering, University of Connecticut, Storrs, Connecticut 06269-1157 (United States)], E-mail: stern@bgu.ac.il

2008-11-01

The common approach in digital imaging follows the sample-then-compress framework. According to this approach, in the first step as many pixels as possible are captured and in the second step the captured image is compressed by digital means. The recently introduced theory of compressed sensing provides the mathematical foundation necessary to combine these two steps in a single one, that is, to compress the information optically before it is recorded. In this paper we overview and extend an optical implementation of compressed sensing theory that we have recently proposed. With this new imaging approach the compression is accomplished inherently in the optical acquisition step. The primary feature of this imaging approach is a randomly encoded aperture realized by means of a random phase screen. The randomly encoded aperture implements random projection of the object field in the image plane. Using a single exposure, a randomly encoded image is captured which can be decoded by proper decoding algorithm.

Atomistic simulation of rapid compression of fractured silicon carbide

International Nuclear Information System (INIS)

Romano, A.; Li, J.; Yip, S.

2006-01-01

Deformation mechanisms of a crack in silicon carbide under high-rate compression are investigated by molecular dynamics simulation. The penny-shaped crack is in tension throughout the simulation while a variable compression is applied in an in-plane direction. Two different mechanisms of crack-tip response are observed: (1) At low tension, a disordered band forms from the crack surface in the direction orthogonal to the compression, which grows as the compressional force is increased in a manner suggesting a stress-induced transition from an ordered to a disordered phase. Moreover the crack is observed to close. (2) At a tension sufficient to allow the crack to remain open, the compressional stress induces formation of disordered regions along the boundaries of the opened crack, which grow and merge into a band as the compression proceeds. This process is driven by bending of the initial crack, which transforms into a curved slit. This mechanism induces incorporation of fragments of perfect crystal into the disordered band. Similar mechanisms have been experimentally observed to occur in porous SiC under high-strain rate compression

RF pulse compression in the NLC test accelerator at SLAC

International Nuclear Information System (INIS)

Lavine, T.L.

1995-01-01

At the Stanford Linear Accelerator Center (SLAC), the authors are designing a Next Linear Collider (NLC) with linacs powered by X-band klystrons with rf pulse compression. The design of the linac rf system is based on X-band prototypes which have been tested at high power, and on a systems-integration test - the Next Linear Collider Test Accelerator (NLCTA) - which is currently under construction at SLAC. This paper discusses some of the systems implications of rf pulse compression, and the use of pulse compression in the NLCTA, both for peak power multiplication and for controlling, by rf phase modulation, intra-pulse variations in the linac beam energy

Active RF Pulse Compression Using An Electrically Controlled Semiconductor Switch

Energy Technology Data Exchange (ETDEWEB)

Guo, Jiquan; Tantawi, Sami; /SLAC

2007-01-10

First we review the theory of active pulse compression systems using resonant delay lines. Then we describe the design of an electrically controlled semiconductor active switch. The switch comprises an active window and an overmoded waveguide three-port network. The active window is based on a four-inch silicon wafer which has 960 PIN diodes. These are spatially combined in an overmoded waveguide. We describe the philosophy and design methodology for the three-port network and the active window. We then present the results of using this device to compress 11.4 GHz RF signals with high compression ratios. We show how the system can be used with amplifier like sources, in which one can change the phase of the source by manipulating the input to the source. We also show how the active switch can be used to compress a pulse from an oscillator like sources, which is not possible with passive pulse compression systems.

Efficient Lossy Compression for Compressive Sensing Acquisition of Images in Compressive Sensing Imaging Systems

Directory of Open Access Journals (Sweden)

Xiangwei Li

2014-12-01

Full Text Available Compressive Sensing Imaging (CSI is a new framework for image acquisition, which enables the simultaneous acquisition and compression of a scene. Since the characteristics of Compressive Sensing (CS acquisition are very different from traditional image acquisition, the general image compression solution may not work well. In this paper, we propose an efficient lossy compression solution for CS acquisition of images by considering the distinctive features of the CSI. First, we design an adaptive compressive sensing acquisition method for images according to the sampling rate, which could achieve better CS reconstruction quality for the acquired image. Second, we develop a universal quantization for the obtained CS measurements from CS acquisition without knowing any a priori information about the captured image. Finally, we apply these two methods in the CSI system for efficient lossy compression of CS acquisition. Simulation results demonstrate that the proposed solution improves the rate-distortion performance by 0.4~2 dB comparing with current state-of-the-art, while maintaining a low computational complexity.

Fringe pattern information retrieval using wavelets

Science.gov (United States)

Sciammarella, Cesar A.; Patimo, Caterina; Manicone, Pasquale D.; Lamberti, Luciano

2005-08-01

Two-dimensional phase modulation is currently the basic model used in the interpretation of fringe patterns that contain displacement information, moire, holographic interferometry, speckle techniques. Another way to look to these two-dimensional signals is to consider them as frequency modulated signals. This alternative interpretation has practical implications similar to those that exist in radio engineering for handling frequency modulated signals. Utilizing this model it is possible to obtain frequency information by using the energy approach introduced by Ville in 1944. A natural complementary tool of this process is the wavelet methodology. The use of wavelet makes it possible to obtain the local values of the frequency in a one or two dimensional domain without the need of previous phase retrieval and differentiation. Furthermore from the properties of wavelets it is also possible to obtain at the same time the phase of the signal with the advantage of a better noise removal capabilities and the possibility of developing simpler algorithms for phase unwrapping due to the availability of the derivative of the phase.

Alvar engine. An engine with variable compression ratio. Experiments and tests

Energy Technology Data Exchange (ETDEWEB)

Erlandsson, Olof

1998-09-01

This report is focused on tests with Variable Compression Ratio (VCR) engines, according to the Alvar engine principle. Variable compression ratio means an engine design where it is possible to change the nominal compression ratio. The purpose is to increase the fuel efficiency at part load by increasing the compression ratio. At maximum load, and maybe supercharging with for example turbocharger, it is not possible to keep a high compression ratio because of the knock phenomena. Knock is a shock wave caused by self-ignition of the fuel-air mix. If knock occurs, the engine will be exposed to a destructive load. Because of the reasons mentioned it would be an advantage if it would be possible to change the compression ratio continuously when the load changes. The Alvar engine provides a solution for variable compression ratio based on well-known engine components. This paper provides information about efficiency and emission characteristics from tests with two Alvar engines. Results from tests with a phase shift mechanism (for automatic compression ratio control) for the Alvar engine are also reviewed Examination paper. 5 refs, 23 figs, 2 tabs, 5 appendices

30 CFR 75.1730 - Compressed air; general; compressed air systems.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compressed air; general; compressed air systems... Compressed air; general; compressed air systems. (a) All pressure vessels shall be constructed, installed... Safety and Health district office. (b) Compressors and compressed-air receivers shall be equipped with...

MRI evaluation and treatment of osteoporotic vertebral compression fracture

International Nuclear Information System (INIS)

Yamaguchi, Ken; Otani, Koji

2003-01-01

The purpose of this study was to investigate the relation between Gd-DTPA enhanced MRI findings and the prognosis of the fractured vertebral body in the patients with fresh osteoporotic compression vertebral fractures. Subjects were 8 cases, 11 vertebrae. All of the cases were treated with no bed rest and no corset. MRI and radiographs were taken within 1 week after injury. MRI signal intensity of the fractured vertebral body altered low on T1WI at acute phase. When the fractured vertebrae were enhanced at whole area with Gd-DTPA at acute phase, the vertebrae showed no progression of wedge deformity by follow up radiographs. On the other hand, when the fractured vertebrae were not enhanced at whole area, the vertebrae showed progression of wedge deformity. These findings suggests that vertebral fractures in osteoporosis should be taken MRI including GD-DTPA in acute phase after injury. When the fractured vertebrae are enhanced with Gd-DTPA in whole body at acute phase, the fracture may need no special treatment. In conclusion, Gd-DTPA enhanced MRI may be useful to determine the prognosis of the osteoporotic compression fracture. (author)

Extraction of Lesion-Partitioned Features and Retrieval of Contrast-Enhanced Liver Images

Directory of Open Access Journals (Sweden)

Mei Yu

2012-01-01

Full Text Available The most critical step in grayscale medical image retrieval systems is feature extraction. Understanding the interrelatedness between the characteristics of lesion images and corresponding imaging features is crucial for image training, as well as for features extraction. A feature-extraction algorithm is developed based on different imaging properties of lesions and on the discrepancy in density between the lesions and their surrounding normal liver tissues in triple-phase contrast-enhanced computed tomographic (CT scans. The algorithm includes mainly two processes: (1 distance transformation, which is used to divide the lesion into distinct regions and represents the spatial structure distribution and (2 representation using bag of visual words (BoW based on regions. The evaluation of this system based on the proposed feature extraction algorithm shows excellent retrieval results for three types of liver lesions visible on triple-phase scans CT images. The results of the proposed feature extraction algorithm show that although single-phase scans achieve the average precision of 81.9%, 80.8%, and 70.2%, dual- and triple-phase scans achieve 86.3% and 88.0%.

Preferred Compression Speed for Speech and Music and Its Relationship to Sensitivity to Temporal Fine Structure.

Science.gov (United States)

Moore, Brian C J; Sęk, Aleksander

2016-09-07

Multichannel amplitude compression is widely used in hearing aids. The preferred compression speed varies across individuals. Moore (2008) suggested that reduced sensitivity to temporal fine structure (TFS) may be associated with preference for slow compression. This idea was tested using a simulated hearing aid. It was also assessed whether preferences for compression speed depend on the type of stimulus: speech or music. Twenty-two hearing-impaired subjects were tested, and the stimulated hearing aid was fitted individually using the CAM2A method. On each trial, a given segment of speech or music was presented twice. One segment was processed with fast compression and the other with slow compression, and the order was balanced across trials. The subject indicated which segment was preferred and by how much. On average, slow compression was preferred over fast compression, more so for music, but there were distinct individual differences, which were highly correlated for speech and music. Sensitivity to TFS was assessed using the difference limen for frequency at 2000 Hz and by two measures of sensitivity to interaural phase at low frequencies. The results for the difference limens for frequency, but not the measures of sensitivity to interaural phase, supported the suggestion that preference for compression speed is affected by sensitivity to TFS. © The Author(s) 2016.

Ethics issues in retrievability

International Nuclear Information System (INIS)

Jensen, M.; Larsson, C.M.; Norden, M.

2000-01-01

We can isolate some issues, which should not be unresolved for a longer period of time. Disputes over well-defined waste management options fall in this category. The concept of retrievability has a possibility to invoke a series of questions in the minds of both specialists and non-specialists. It is intrinsically vague, in that it may refer to different phases in the repository's life, and to both open and closed repositories in the long time frame. Requirements for retrievability opens a series of issues, including open-ended philosophical question, which may give the impressions that things are not properly taken care of, since the experts differ in opinion. If such disputes cannot be resolved by consulting the existing legal framework, efforts should be made to put them to trial in the proper forum, i.e. parliament and national or local government or authorities, depending on the problem. In contrast, the value of institutional controls can easily be seen as an ethical value, whether included in the regulation of not. It has the potential to deter human intrusion and to allow remedial action by carrying information about a repository. (author)

Origin of the low compressibility in hard nitride spinels

DEFF Research Database (Denmark)

Mori-Sánchez, P.; Marqués, M.; Beltrán, A.

2003-01-01

A microscopic investigation of first-principles electron densities of gamma-A(3)N(4) (A:C,Si,Ge) spinels reveals a clear relationship between the compressibility and the chemical bonding of these materials. Three striking findings emanate from this analysis: (i) the chemical graph is governed...... by a network of highly directional strong bonds with covalent character in gamma-C3N4 and different degrees of ionic polarization in gamma-Si3N4 and gamma-Ge3N4, (ii) nitrogen is the lowest compressible atom controlling the trend in the bulk modulus of the solids, and (iii) the group-IV counterions show strong...... site dependent compressibilities enhancing the difficulty in the synthesis of the spinel phases of these nitrides....

The Effects of Emotional Visual Context on the Encoding and Retrieval of Body Odor Information.

Science.gov (United States)

Parma, Valentina; Macedo, Stephanie; Rocha, Marta; Alho, Laura; Ferreira, Jacqueline; Soares, Sandra C

2018-04-01

Conditions during information encoding and retrieval are known to influence the sensory material stored and its recapitulation. However, little is known about such processes in olfaction. Here, we capitalized on the uniqueness of body odors (BOs) which, similar to fingerprints, allow for the identification of a specific person, by associating their presentation to a negative or a neutral emotional context. One hundred twenty-five receivers (68 F) were exposed to a male BO while watching either criminal or neutral videos (encoding phase) and were subsequently asked to recognize the target BO within either a congruent or an incongruent visual context (retrieval phase). The results showed that criminal videos were rated as more vivid, unpleasant, and arousing than neutral videos both at encoding and retrieval. Moreover, in terms of BO ratings, we found that odor intensity and arousal allow to distinguish the target from the foils when congruent criminal information is presented at encoding and retrieval. Finally, the accuracy performance was not significantly different from chance level for either condition. These findings provide insights on how olfactory memories are processed in emotional situations.

Full-Physics Inverse Learning Machine for Satellite Remote Sensing Retrievals

Science.gov (United States)

Loyola, D. G.

2017-12-01

The satellite remote sensing retrievals are usually ill-posed inverse problems that are typically solved by finding a state vector that minimizes the residual between simulated data and real measurements. The classical inversion methods are very time-consuming as they require iterative calls to complex radiative-transfer forward models to simulate radiances and Jacobians, and subsequent inversion of relatively large matrices. In this work we present a novel and extremely fast algorithm for solving inverse problems called full-physics inverse learning machine (FP-ILM). The FP-ILM algorithm consists of a training phase in which machine learning techniques are used to derive an inversion operator based on synthetic data generated using a radiative transfer model (which expresses the "full-physics" component) and the smart sampling technique, and an operational phase in which the inversion operator is applied to real measurements. FP-ILM has been successfully applied to the retrieval of the SO2 plume height during volcanic eruptions and to the retrieval of ozone profile shapes from UV/VIS satellite sensors. Furthermore, FP-ILM will be used for the near-real-time processing of the upcoming generation of European Sentinel sensors with their unprecedented spectral and spatial resolution and associated large increases in the amount of data.

Rebound Attack on the Full LANE Compression Function

DEFF Research Database (Denmark)

Matusiewicz, Krystian; Naya-Plasencia, Maria; Nikolic, Ivica

2009-01-01

In this work, we apply the rebound attack to the AES based SHA-3 candidate Lane. The hash function Lane uses a permutation based compression function, consisting of a linear message expansion and 6 parallel lanes. In the rebound attack on Lane, we apply several new techniques to construct...... a collision for the full compression function of Lane-256 and Lane-512. Using a relatively sparse truncated differential path, we are able to solve for a valid message expansion and colliding lanes independently. Additionally, we are able to apply the inbound phase more than once by exploiting the degrees...

Direct phase retrieval in double blind Fourier holography.

Science.gov (United States)

Raz, Oren; Leshem, Ben; Miao, Jianwei; Nadler, Boaz; Oron, Dan; Dudovich, Nirit

2014-10-20

Phase measurement is a long-standing challenge in a wide range of applications, from X-ray imaging to astrophysics and spectroscopy. While in some scenarios the phase is resolved by an interferometric measurement, in others it is reconstructed via numerical optimization, based on some a-priori knowledge about the signal. The latter commonly use iterative algorithms, and thus have to deal with their convergence, stagnation, and robustness to noise. Here we combine these two approaches and present a new scheme, termed double blind Fourier holography, providing an efficient solution to the phase problem in two dimensions, by solving a system of linear equations. We present and experimentally demonstrate our approach for the case of lens-less imaging.

Mechanisms of anomalous compressibility of vitreous silica

Science.gov (United States)

Clark, Alisha N.; Lesher, Charles E.; Jacobsen, Steven D.; Sen, Sabyasachi

2014-11-01

The anomalous compressibility of vitreous silica has been known for nearly a century, but the mechanisms responsible for it remain poorly understood. Using GHz-ultrasonic interferometry, we measured longitudinal and transverse acoustic wave travel times at pressures up to 5 GPa in vitreous silica with fictive temperatures (Tf) ranging between 985 °C and 1500 °C. The maximum in ultrasonic wave travel times-corresponding to a minimum in acoustic velocities-shifts to higher pressure with increasing Tf for both acoustic waves, with complete reversibility below 5 GPa. These relationships reflect polyamorphism in the supercooled liquid, which results in a glassy state possessing different proportions of domains of high- and low-density amorphous phases (HDA and LDA, respectively). The relative proportion of HDA and LDA is set at Tf and remains fixed on compression below the permanent densification pressure. The bulk material exhibits compression behavior systematically dependent on synthesis conditions that arise from the presence of floppy modes in a mixture of HDA and LDA domains.

Phased-array radars

Science.gov (United States)

Brookner, E.

1985-02-01

The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US military systems COBRA DANE and PAVE PAWS as examples.

Retrieval Attempts Enhance Learning, but Retrieval Success (versus Failure) Does Not Matter

Science.gov (United States)

Kornell, Nate; Klein, Patricia Jacobs; Rawson, Katherine A.

2015-01-01

Retrieving information from memory enhances learning. We propose a 2-stage framework to explain the benefits of retrieval. Stage 1 takes place as one attempts to retrieve an answer, which activates knowledge related to the retrieval cue. Stage 2 begins when the answer becomes available, at which point appropriate connections are strengthened and…

Retrieval options study

International Nuclear Information System (INIS)

1980-03-01

This Retrieval Options Study is part of the systems analysis activities of the Office of Nuclear Waste Isolation to develop the scientific and technological bases for radioactive waste repositories in various geologic media. The study considers two waste forms, high level waste and spent fuel, and defines various classes of waste retrieval and recovery. A methodology and data base are developed which allow the relative evaluation of retrieval and recovery costs and the following technical criteria: safety; technical feasibility; ease of retrieval; probable intact retrieval time; safeguards; monitoring; criticality; and licensability. A total of 505 repository options are defined and the cost and technical criteria evaluated utilizing a combination of facts and engineering judgments. The repositories evaluated are selected combinations of the following parameters: Geologic Media (salt, granite, basalt, shale); Retrieval Time after Emplacement (5 and 25 years); Emplacement Design (nominal hole, large hole, carbon steel canister, corrosion resistant canister, backfill in hole, nominal sleeves, thick wall sleeves); Emplacement Configuration (single vertical, multiple vertical, single horizontal, multiple horizontal, vaults; Thermal Considerations; (normal design, reduced density, once-through ventilation, recirculated ventilation); Room Backfill; (none, run-of-mine, early, 5 year delay, 25 year delay, decommissioned); and Rate of Retrieval;

Compressive performance and crack propagation in Al alloy/Ti{sub 2}AlC composites

Energy Technology Data Exchange (ETDEWEB)

Hanaor, D.A.H., E-mail: dorian.hanaor@sydney.edu.au [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Hu, L. [Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Kan, W.H.; Proust, G. [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Foley, M. [Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, NSW 2006 (Australia); Karaman, I.; Radovic, M. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States)

2016-08-30

Composite materials comprising a porous Ti{sub 2}AlC matrix and Al 6061 alloy were fabricated by a current-activated pressure assisted melt infiltration process. Coarse, medium and fine meso-structures were prepared with Al alloy filled pores of differing sizes. Materials were subjected to uniaxial compressive loading up to stresses of 668 MPa, leading to the failure of specimens through crack propagation in both phases. As-fabricated and post-failure specimens were analysed by X-ray microscopy and electron microscopy. Quasi-static mechanical testing results revealed that compressive strength was the highest in the fine structured composite materials. While the coarse structured specimens exhibited a compressive strength of 80% relative to this. Reconstructed micro-scale X-ray tomography data revealed different crack propagation mechanisms. Large planar shear cracks propagated throughout the fine structured materials while the coarser specimens exhibited networks of branching cracks propagating preferentially along Al alloy-Ti{sub 2}AlC phase interfaces and through shrinkage pores in the Al alloy phase. Results suggest that control of porosity, compensation for Al alloy shrinkage and enhancement of the Al alloy-Ti{sub 2}AlC phase interfaces are key considerations in the design of high performance metal/Ti{sub 2}AlC phase composites.

RF pulse compression in the NLC test accelerator at SLAC

International Nuclear Information System (INIS)

Lavine, T.L.

1995-01-01

At the Stanford Linear Accelerator Center (SLAC), we are designing a Next Linear Collider (NLC) with linacs powered by X-band klystrons with rf pulse compression. The design of the linac rf system is based on X-band prototypes which have been tested at high power, and on a systems-integration test---the Next Linear Collider Test Accelerator (NLCTA)---which is currently under construction at SLAC. This paper discusses some of the systems implications of rf pulse compression, and the use of pulse compression in the NLCTA, both for peak power multiplication and for controlling, by rf phase modulation, intra-pulse variations in the linac beam energy. copyright 1995 American Institute of Physics

SeqCompress: an algorithm for biological sequence compression.

Science.gov (United States)

Sardaraz, Muhammad; Tahir, Muhammad; Ikram, Ataul Aziz; Bajwa, Hassan

2014-10-01

The growth of Next Generation Sequencing technologies presents significant research challenges, specifically to design bioinformatics tools that handle massive amount of data efficiently. Biological sequence data storage cost has become a noticeable proportion of total cost in the generation and analysis. Particularly increase in DNA sequencing rate is significantly outstripping the rate of increase in disk storage capacity, which may go beyond the limit of storage capacity. It is essential to develop algorithms that handle large data sets via better memory management. This article presents a DNA sequence compression algorithm SeqCompress that copes with the space complexity of biological sequences. The algorithm is based on lossless data compression and uses statistical model as well as arithmetic coding to compress DNA sequences. The proposed algorithm is compared with recent specialized compression tools for biological sequences. Experimental results show that proposed algorithm has better compression gain as compared to other existing algorithms. Copyright © 2014 Elsevier Inc. All rights reserved.

National waste terminal storage repository in a bedded salt formation for spent unreprocessed fuel. Special study No. 1. 25-year retrievability

International Nuclear Information System (INIS)

1978-12-01

National Waste Terminal Storage Repository 2 (NWTSR2), in bedded salt, for spent unreprocessed fuel is the subject of a conceptual design project which began in January 1977. In the base conceptual design the spent fuel is to be stored in a retrievable mode for 5 years. This report presents the results of a separate study on 25-year retrievability with open storage rooms. Drawings prepared for 25-year retrievability are only those which differ from the companion 5-year retrievability drawings which comprise Volume II of the Conceptual Design Report (CDR). NWTSR2 capital facilities originally were to be constructed in phases. Phase I was to include those facilities required for the first 5 years of operation, which were hypothesized to be from 1985 through 1990; Phase II was to include facilities required from 1991 until the capacity of the 2000-acre mine was reached. These dates are used as the basis for conceptual design and for Special Study No. 1 but do not represent actual schedule dates for the repository. The terms Phase I and Phase II are used throughout the drawings and test, so they need to be understood. However, it is not now intended to phase the capital construction because of the relatively small effort represented by Phase II surface construction. An optional future expansion of the mine, Phase III, would add 1000 acres on the end of the mine opposite the shaft pillar. The optional Phase III expansion would commence operation upon completion of Phase II operations. The drawings and design comparisons for Phase III mine operations appear only in this report